MANUAL OF CHEMISTRY; 
CONTAINING 
THE PRINCIPAL FACTS OF THE SCIENCE, ARRANGED IN THE ORDER IN 
WHICH THEY ARE DISCUSSED AND ILLUSTRATED IN THE 
LECTURES AT THE ROYAL INSTITUTION OF 
GREAT BRITAIN. 
0r 
BY 
WILLIAM THOMAS BIIANHE, 
Secretary of the Royal Society of London; Fellow of the Royal Society of Edinburgh; Member of, 
and Professor of Chemistry in the Royal Institution of Great Britain; Professor of Chemistry 
and Materia Medica to the Society of Apothecaries of the City of London; Member 
of the Geological Society of London; Honorary Member of the Literary 
and Philosophical Society of New-York; of the Physico-Medical 
Society of Erlangen: and of the Pharmaceutical 
Society of Petersburg!!. 
THE FIRST AMERICAN, 
From, the Second London Edition. 
£fjm Toltttues in ©ne* 
TO WHICH ARE ADDED 
NOTES AND EMENDATIONS: 
BY 
WILLIAM JAMES MACNEVEN, M.D„ 
Professor of Chemistry in the College of Physicians and Surgeons of the 
University of the State of New-York, and Member of 
the Literary and Philosophical Society. 
JVEW-YORK: 
PRINTED AND PUBLISHED BY GEORGE LONG, 
JVo. 71, Pearl-Street. 
1821, Southern District of Netu-York, si. 
BE IT REMEMBERED, That on the fourteenth day of November, in the forty-sixth year of the 
Independence of the United States of America, George Long, of the said district, hath deposited in 
this office the title of a book, the right whereof he claims as proprietor, in the words following, to wit: 
“ A Manual of Chemistry ; containing the principal facts of the Science arranged in the Order in 
which they are discussed and illustrated in the Lectures at the Royal Institution of Great Britain. 
By William Thomas Brande, Secretary of the Royal Society of London: Fellow of the Royal Society 
of Edinburgh: Member and Professor of Chemistry in the Royal Institution of Great Britain- Pro- 
fessor of Chemistry and Materia Medica to the Society of Apothecaries of the City of London : Mem- 
ber of the Geological Society of London : Honorary Member of the Literary and Philosophical So- 
ciety of New-York: of the Physico-Medical Society of Erlangen: and of the Pharmaceutical Society 
of Petersburgh.—The first American from the Second London Edition.—Three Volumes in one. To 
which are added Notes and Emendations, by William James Macneven, MP- Professor of Chemistry 
in the College of Physicians and Surgeons of the University of the State of New-York, and Member 
of the Literary and Philosophical Society. 
In conformity to the act of the Congress of the United States, ent? led, “ An act for the encourage- 
ment of learning, by securing the copies of maps, charts, and books, to the authors and proprietors of 
such copies, during the time therein mentioned.” And also to an act, entitled, “ An act, supplementa- 
ry to an act, entitled, An act for the encouragement of learning, by securing the copies of maps, charts, 
and books, to the authors and proprietors of such copies, during the times therein mentioned, and extend- 
ing the benefits thereof to the arts of designing, engraving, and etching historical and other prints.” 
JAMES DILL, 
Clerk of the Southern District of New-York. ADVERTISEMENT. 
A class book that should comprehend in regular order, 
the text of what is delivered in lectures, and what is ex- 
pected from the candidate at examination, is a thing alto- 
gether so desirable for Professor and Student, that I had 
contemplated the compilation of such a work for the 
use of my pupils in this University, when, very oppor- 
tunely, 1 received Mr. Brande’s Manual. Having pe- 
rused this well arranged outline of a course of Chemistry, 
1 deemed my projected undertaking unnecessary: and 
yet, 1 could not adopt his book, nor recommend it to my 
class entirely in the shape he gives it. The atomic 
theory, as delivered by him, differs considerably from 
the view l take of it; and, as I hold this to be the ex- 
ceptionable part of Mr. Brande’s otherwise excellent 
performance, it only remained for me to change, or as I 
would fain say, amend it, in that particular. It is ea- 
sily seen that his specific gravities and atomic weights 
are frequently inaccurate: nor is the error, perhaps, 
entirely accidental. Representative numbers recently 
determined in a very satisfactory manner are still given 
by Mr. Brande as they were represented five or six years 
ago, although Dr. Prout, but more especially Dr. Thom- 
son has demonstrated that they required correction. The 
latter has clearly proved that the atoms of the simple 
bodies nitrogen, oxygen, chlorine, carbon, sulphur, 
phosphorus, iodine, are even multiples of the weight of 
an atom of hydrogen. He has also shown that when 
hydrogen is made the unity of weight, and oxygen the 
unity of specific gravity, then the weight of the atom 
of a gaseous body is either equal to the specific gravi- 
ty, or some multiple of the same by a whole number. If the specific gravity of oxygen be 1, that of hydro- 
gen will be 0.0625, which x by 2 = 0.125, weight of the 
atom of hydrogen. In most cases of this kind the atomic 
weight is double the specific gravity; in a few, however, 
twice 2 is found to be the proper multiplier: the reason 
of this difference is not very obvious; but in the first 
the combination is most energetic. See the table add- 
ed, p. 3 61. 
In consequence of these views, the representative num- 
bers for the elementary and compound atoms, through- 
out the whole work, have been altered to correspond 
with the results of the latest discoveries and improve- 
ments. Almost all the notes, likewise, are additions; In 
other respects, and wherever the investigations of Mr. 
Brande himself are given as authority, the text has 
suffered no change. But intending the manual only 
for a class book and text of my lectures, 183 pages of 
preface have been left out and 102 pages of index 
abridged to two. The first, though well composed, 
could, in this instance, be the better spared, as it 
is but an enlarged, though in several particulars, an im- 
proved version of the author’s earlier dissertation on the 
progress of chemical science, of which an edition from 
the Boston press must be already known to the Ameri- 
can reader. A wish to avoid making the publication too 
voluminous to be read in connexion with other studies, 
or rendering the price too high for beginners, induced 
me to retrench what was, in some measure, unnecessa- 
ry ; and, applying to myself the same rule, I forbear 
to lengthen this advertisement. 
New-York, Nov. 20, 1821. PREFACE. 
Though the following pages are chiefly intended for 
students, it is trusted that the proficient will find them a 
useful compendium of Chemistry. 
The arrangement of the materials differs from that 
sanctioned by our best elementary writers, but it has 
been adopted in consequence of some years’ experience 
of its advantages in teaching the principles of the science. 
in the first chapter, the leading facts connected with 
the general laws of chemical changes are discussed un- 
der the separate heads of Attraction, Heat, and Elec- 
tricity. The second chapter relates to the properties of 
Radiant Matter, and its influence upon the composition 
of bodies. In the third and fourth chapters I have de- 
tailed the sources and properties of the Simple Sup- 
porters of Combustion, and of the Elementary Acidifi- 
able Substances, and their mutual combinations. The 
fifth chapter contains an account of the Metals, and of 
their compounds with the bodies previously described, 
and with each other. 
The sixth chapter embraces such details respecting 
the Assay and Analysis of Metalliferous Compounds, 
as are necessarily omitted under the individual history 
of the metals : in this division of the book I have avail- 
ed myself largely of the invaluable analytical labours 
of Klaproth, and have selected from other sources such 
instances as I conceived best adapted to assist the stu- 
dent in acquiring correct notions of this department of 
chemical study ; the processes detailed have, with few 
exceptions, been submitted to the test of experimental 
repetition in the laboratory of the Royal Institution, 
and those which have not been thus verified, are drawn 
from sources of the highest authority. 
In the seventh chapter I have aimed at a succinct des- 
cription of the means of analyzing mineral waters, and 
as their examination is frequently desirable where the 
conveniences of a regular laboratory are not attainable, 
I have subjoined a short account of the tests and appa- 
ratus required in this branch of research. Upon the subject of analysis in general, the student 
will find inexhaustible information in the writings of 
Klaproth, and in the Essays of Vauquelin; the former 
have only been in part translated into the English lan- 
guage ,• and the latter are scattered through various pe- 
riodical publications, especially the Journal des Mints, 
and the An.nales de Chimie. The last thirty volumes of 
the Philos)phi cat Transactions are also rich in detached 
essays, by our most eminent chemists, illustrative of the 
art of analysis. A judicious selection from these sources 
upon an extended scale would be truly valuable to the 
practical chemist, and would materially contribute to fa- 
cilitate the progress of our analytical inquiries. 
For general directions concerning the art of analysis, 
and for many useful and original hints relative to the 
manipulations of the laboratory, I have much satisfac- 
tion in referring to Mr. Children’s translation of the 
fourth volume of M. Thenard’s Trade de Chimie. The 
reader will observe, that in Chapter VI. 1 have availed 
myself of this work, which the student will do well to 
consult in detail. 
The eighth and ninth chapters are assigned to Vege- 
table and Animal Products ; and the concluding chap- 
ter contains the heads of Geological inquiry. 
In the Appendix to this work will be found Ta- 
bles, chiefly useful as presenting a synoptic view of most 
of the simple and compound bodies, with their represen- 
tative or equivalent numbers; these may easily be trans- 
ferred to a logometric scale, as recommended by Dr. 
Wollaston, who has thus furnished the laboratory with 
one of its most useful implements. 
The principal materials of this book have been drawn 
from the notes that I have employed in my different 
courses of lectures, and these are partly original, and 
partly compiled from various sources; although there- 
fore 1 have in most intances scrupulously referred to the 
authorities quoted, it is possible that this may have been 
sometimes omitted, and for such omissions, 1 now beg to apologize, The systematic and elementary works that 
I have chiefly relied on for assistance, are the Systems 
of Dr. T. Thomson, and of the late Dr. John Murray; 
the Traitede Chimie of M. Thenard; and the Elements of. 
Sir Humphry Davy, and of Dr. William Henry The 
Chemical Dictionary of Messrs. Aikin, I have Iso often 
consulted with advantage, especially in reh ion to the 
Chemistry of the Arts. Dr I re’s Dictionary of C/>- mis- 
/ry did not fall into my hands till this work was nearly 
ready for publication, or 1 should have availed myself 
of the valuable information in which it abounds, both ori- 
ginal and compiled. 
I think it also right to add, that much of this work has 
been written in the Laboratory, where the results of ex- 
periments have been immediately transferred to its pages; 
and where T have uniformly received the assistance ot Mr. 
M. Faraday, whose accuracy and skill as an operator have 
proved of essential service in all my proceedings. 
The following description of the ground plan (Plate 
I.) will serve to explain its general arrangement. 
a is a part appropriated to an audience, b is the body 
of the Laboratory. 
a The entrance. 
h An open chimney for the reception of moveable 
furnaces. 
c A wind furnace. (Plate 111., Fig. 2.) 
d A reverberatory and assay furnace. 
e A stove with a sunk flue, for warming the Laboratory. 
f A table. 
g A sand furnace. (Plate HI., Fig. 1.) 
This has lately been transferred to the place of the 
centre table p, and communicates by a descending flue 
with the same chimney. 
h A sink with a plentiful supply of water. 
i A table with cupboards below it. 
k A furnace for the production of gas from coal, Sfc. 
I A cast-iron steam boiler for the abundant supply of 
hot water, and of steam when required. 
m A recess lighted from above, containing a bellows- blowpipe, and communicating with three flues n n n, for 
the reception of the chimneys of portable furnaces. 
The gas purifiers also stand in this recess. 
o A forge furnace placed in a similar recess, with flues 
for occasional purposes. 
p p p Tables with drawers. 
q A gasometer from which tubes issue for the supply 
of the Laboratory, and of the lecture room, with coal gas. 
r A small store-room and cellar for fuel, Sfc. 
s s Recesses for apparatus. 
t Doorway leading to an apartment for apparatus, SCc. 
Plate III. contains a representation of the most useful 
furnaces of the Laboratory. 
Fig. 1. A sand furnace ; a the larger bath; b the small- 
er one, which may occasionally be removed for the pur- 
pose of employing the fire-place for crucibles, or of 
inserting the boiler of a still. 
Fig. 2. Section of the wind-furnace ; c Plate I. a is 
a flue communicating wilh the exterior of the building, 
for the admission of cold air to the fire-place; ithe ash- 
hole ; c c two grates, the upper of which mav be remov- 
ed when a deep fire-place is wanted; d an aperture 
which may be closed by a moveable fire-brick; e the 
chimney; f a register. 
Fig. 3. Knight’s portable furnace, made of wrought 
iron, and lined with fire-brick. It is convenient for a 
variety of operations, conducted upon a small scale; «is a 
door for the passage of the neck of a retort when distilla- 
tion is performing in the open fire, as seen in the wood-cut 
at page 120; b is an aperture to which there is a corres- 
ponding one on the opposite side for the admission of a 
tube to pass through the furnace, as showm at page 81. 
Fig. 4. A portable assay-furnace; a is the nffuffle re- 
presented in Fig. 5. 
Fig. 6, 7, and 8, are evaporating basins; 9, a Plati- 
num crucible and cover; 10, 11, Hessian crucibles; 12, 
13, 14, 15, the principal varieties of tongs useful in the 
Laboratory. MANUAL OF CHEMISTRY. 
CHAPTER I. 
OF THE POWERS AND PROPERTIES OF MATTER, AND OF THE GENERAL 
DAWS OF CHEMICAL CHANGES. 
1. It is the object of Chemistry to investigate all changes in the con-c 
stitution of matter, whether effected by heat, mixture or other means, c 
Its general range, therefore, is so extensive, and the individual cases 
requiring explanation, so numerous, that Arrangement is of the first 
consequence to its successful study ; and, in the present state of our 
knowledge, it will be found most convenient to begin with the discus- 
sions relating to the general powers or properties of matter, and after- 
wards to proceed to the examination of individual substances, and to 
the phenomena which they offer when presented to each other under 
circumstances favourable to the exertion of their mutual chemical 
agencies. 
2. The powers and properties of matter, connected with chemical 
changes, may be considered under the heads of 
1. Homogeneous Attraction. 
2. Heterogeneous Attraction, or Affinity. 
3. Heat. 
4. Electricity. 
Section I. Homogeneous Attraction. 
3. Attraction may he regarded as acting at sensible and at insen- 
sible distances. In the former case it is called gravitation. It is the 
power by which substances are propelled towards the earth ; it exists 
in all 'known forms of matter ; and it acts directly as the mass, and in- 
versely as the square of the distance : Restrained by inertia, it pre- 
serves the planetary bodies in their orbits, presides over their move- 
ments, and tends to confer upon the system of the universe that con- 
summate harmony which the genius of Newton has unveiled. 
4. Attraction is also exerted at insensible distances, and among the 
minutest atoms of matter. It thus preserves the form, and modifies 
the texture, of solids, gives a spherical figure to fluids, causes the ad- 
Object of 
Chemistry. 
Attraction at 
sensible (Us- 
ance*. 
Attraction at 
insensible dis- 
tances- ATTRACTION. 
hesion of Surfaces, and influences the mechanical characters of bodies t 
and, when it operates upon dissimilar particles, it produces their union, 
giving rise to new and infinitely-varied productions. 
5. The results of attraction, as relating to the texture and forms of 
matter, are influenced by the circumstances under which it has taken 
place. Sometimes the particles are, as it were, indiscriminately col- 
lected ; at others, they are beautifully arranged, giving rise to regu- 
lar and determinate figures : In this case, bodies of the same compo- 
sition almost invariably affect the same form ; hence we are often en- 
abled to infer the composition of a substance from accurate inspection 
of its external or mechanical characters. 
6. The regular polyhedral solids thus resulting from the influence 
of attraction upon certain kinds of matter, are usually called crystals ; 
and the bodies are said to be susceptible of crystallization. 
7. To enable the particles of bodies to assume that regular form 
which chrystals exhiliit, it is obvious that they must have freedom of 
motion ; and accordingly, the first step towai’ds obtaining a body in its 
crystalline form, is to confer upon it either the liquid or aeriform state. 
The former is usually effected by solution in water; the latter by ex- 
posure to heat. 
8. When common salt is dissolved in writer, its particles may be re- 
garded as disposed at regular distances throughout the fluid ; and if the 
quantity of w ater be considerable, the particles will be too far asunder 
to exert reciprocal attraction ; in other words, they w ill be more pow- 
erfully attracted by the water than by each other. If wre now slowly 
get rid of a portion of the water by evaporation, the saline particles 
will gradually approach each other, and they w ill aggregate according 
to certain laws producing a regular solid of a cubic form. 
9. The regularity of this figure will be influenced by the rapidity of 
the evaporation; if the process be slowly conducted, the particles 
unite with great regularity ; if hurried, the crystals are irregular and 
confused. In common cases, the evaporation may be continued till a 
pellicle forms upon the surface of the solution, which indicates that the 
attraction of the saline particles for each other, is becoming superior 
to their attraction for the water. The formation, therefore, of a su- 
perficial pellicle is the common criterion of the fitness of a solution for 
crystallization; but wdiere the object is to obtain very regular and 
very large crystals, the evaporation must be much slower, and carried 
to much less extent; even spontaneous evaporation, or that which 
takes place at common temperatures, must be resorted to. 
10. There are certain bodies w hich may be dissolved or liquefied by 
heat, and during slow cooling, may be made to crystallize. This is the 
case with many of the metals, and with sulphur. Some other substan- 
ces, when heated, readily assume the state of vapour, and, during con- 
densation, present regular crystalline forms ; such as iodine, benzoic 
acid, camphor, fyc.: and in this way crystals of snow are produced by 
the cooling of aqueous vapour. 
11. Some substances are so easily decomposed by heat, and at the 
same time retain water with such avidity, that it is impossible to crystal- 
lize them by any of the above processes ; in these cases crystallization 
may sometimes he effected by placing the Solution under the exhausted 
receiver of an air-pump, over asurface of sulphuric acid, w'hich by abr 
Cpnilitiftns for 
crystalliza- 
tion. 
'i lie figure in- 
fluenced by va- , 
pidity of eva- ' 
poration. \ 
Time for stop- 
ping artificial 
evaporation. 
Crystals form- 
ed by fusion. 
Crystalliza- 
tion^'substan- 
ces 'hose 
composition is 
feeble. crystallization. 
3 
sorbing the vapour as it rises, causes rapid evaporation without increase 
of temperature. 
12. The hardness, brilliancy, and transparency of crystals, often de- 
pend upon their containing water, which sometimes exists in them in 
large quantities. Thus, sulphate of soda, in the state of crystals, con- 
tains more than half its weight. Sulphate of iime, in its crystallized 
form, contains about 20 per cent, of water, which it loses at a red heat, 
and the crystals crumble down into the white pow der called Plaster of 
Paris. This is termed water of crystallization. Some salts part with 
it by simple exposure to a dry air, when they are said to effloresce; 
but there are other salts which deliquesce, or attract water from the 
atmosphere. Those crystals which effloresce by exposure to air, 
may often be conveniently preserved, by slightly oiling their surfaces. 
The best method is, to soak the crystals in oil for a few hours, and 
then to wipe them, and put them up in bottles. 
13. Some salts, in consequence probably of their strong attraction 
for the water that retains them in solution, cannot be brought to cry- 
stallize in the ordinary way. In such cases, crystallization may some- 
times be effected by the addition of substances having a strong affinity 
for water, by which its attraction for the dissolved matters is weaken- 
ed : thus alcohol, added to certain aqueous saline solutions, produces 
a separation of crystals, but they are generally small and indistinct. 
14. When two salts of different solubilities are present in the same 
solution, they often may be separated by crystallization, that which is 
least soluble constituting the earlier crop of crystals. 
15. Crystallization is accelerated, by introducing into the solution 
a nucleus, or solid body, upon which the process begins ; and manu- 
facturers often avail themselves of this circumstance. Thus we see 
sugar-candy crystallized upon strings, and verdigris upon sticks. 
There arc cases in which it is particularly advantageous to put a few 
crystals of the dissolved salt into the solution, which soon cause a crop 
of fresh crystals ; and in some instances, if there be two salts in solu- 
tion, that will most readily separate, of which the crystals have been 
introduced. 
16. A strong saline solution, excluded from the air, will frequently 
crystallize the instant that air is admitted,—a circumstance unsatisfac- 
torily referred to atmospheric pressure. In other cases, agitation 
produces the same effect. These phenomena' seem connected with 
the doctrine of latent heat, but hitherto they have only been imper- 
fectly investigated : in some cases they have been shown by Dr. Ure to 
be affected by electrical changes.—Quarterly Journal, Vol. x., p. 6. 
17. The presence of light also influences the process of crystalliza- 
tion. Thus we see the crystals collected in camphor bottles in drug- 
gists’ windows always most copious upon the surface exposed to light; 
and if we place a solution of nitre in a room which has the light admit- 
ted only through a small hole in the window shutter, crystals will form 
most abundantly upon the side of the basin exposed to the aperture 
through which the light enters, and often the whole mass of crystals 
will turn towrards it. 
Many saline solutions form arborescent crystalline pellicles, when 
left to spontaneous evaporation, which slowly travel up the sides ot 
the basin, and gradually proceed down upon the outside : this process 
also always begins on the side nearest the light, and is often confined’ 
water of crys- 
tallization. 
Kfllorescence 
and deliques- 
cence. 
Crystalliza- 
tion promoted 
by a nucleus* 
Crystallization 
affected by the 
admission of 
air as also by 
agitation. 
Light influen- 
ces crystalli- 
zation. 4 
CRYSTALLIZATION. 
to it. Acetate of lime exhibits this appearance in a very beautiful 
manner.—Aikin’s Diet. Art. Light. 
f 18. We may now proceed to examine the structure of crystallized 
bodies, upon which the Theories of Crystallization are founded. This 
inquiry exposes a connecting link between the Chemical and Mechanic 
cal properties of bodies. 
It is commonly observed, that crystallized bodies affect one form in 
preference to others. The fluor spar of Derbyshire crystallizes in 
cubes : so does common salt. Nitre assumes the form of a six-sided 
prism, and sulphate of magnesia that of a four-sided prism. These 
forms are liable to vary. Fluor spar and salt crystallize sometimes in 
the form of octoedra ; and there are so many forms of carbonate of lime, 
that it is difficult to select that which most commonly occurs. 
r Rome de Lisle referred these variations of form to certain trunca- 
tions of an invariable primitive nucleus ; and Gahn afterwards observed, 
that when a piece of calcareous spar was carefully broken, all its parti- 
cles were of a rhomboidal figure. This induced Bergman to suspect 
the existence of a primitive nucleus in all crystallized bodies (Physi- 
cal and Chemical Essays, Vol. II. p. 1.) When Ilaiiy entered this field 
of inquiry, he not only corroborated the opinions of Bergman, and sub- 
mitted former hypotheses to experimental proof, hut traced with much 
success the laws of crystallization and pointed out the modes of transi- 
tion from primitive to secondary figures.—Traitede Minera logie, Paris, 
1801. 
19. Those who are in the habit of cut- 
ting and polishing certain gems; have long 
known that they only afford smooth sur- 
faces when broken in one direction ; and 
that in others the fracture is irregular and 
uneven. This is the case with crystalliz- 
ed bodies in general. Jf we attempt to 
split a cube of fluor spar with the blade of 
a knife assisted by a hammer we shall 
find that it will only yield kindly in the 
direction of the solid angles ; and pursu- 
ing the divivision in these directions an 
octoedron will be the resulting figure as in 
this diagram. 
20. In splitting a six-sided crystal of calca- 
reous spar, we find that of the six edges of the 
superior base, three alternate edges only will 
yield to the blow : those, for instance, mark- 
ed a, h, c ; and the division will take place 
in a plane inclined at an angle of 45°. The 
three intermediate edges resist this division. 
But in dissecting the inferior base of the crys- 
tal, the intermediate edges will alone yield, 
namely, a, b, c. If we continue this dissec- 
tion in the same directions, we shall at length 
obtain the obtuse rhomboid, which is seen in 
this diagram in its Relative situation to the 
including prism. 
Structure of 
crystallized 
bodies. 
Assume one 
form rather 
than another. 
All varieties of 
crystals of the 
same substance 
have similar 
auclei. 
Gems cannot 
be split 
smoothly but 
in certain di- 
rections. CRYSTALLIZATION. 
21. We thus then arrive at the primitive form of the calcareous spar, 
and from whatever secondary form it has been obtained, it is always a 
rhomboid, having obtuse angles of 105° 5'. But an obtuse rhomboid, 
is also the primitive form of other bodies, as of pearl spar, iron spar, 
and tourmalin. But here the inclination of the surface points out a 
difference. Thus the primitive angle of pearl spar is 106° 5', of iron 
spar 107°, (Wollaston, Phil. Trans. 1812,) and of tourmalin 113° 
10'. 
22. These instances show the necessity of being provided with in- 
struments for measuring the angles of crystals with nice accuracy; 
they are termed goniometers. The simplest of these instruments con- 
sists of a protractor or seme-circular scale of degrees, AA, and a small 
pair of compasses or nippers, B B B B, destined to receive the crystal. 
Instrument for 
measuring the 
angles of crys- 
tals. 
Simplest form 
of the gonio- 
meter. 
The centre of the pair of compasses is made moveable like those of 
the common proportional compasses, so as to permit the legs B B, and 
BCB, to be considerably lengthened or shortened, when the two 
pieces are applied to each other. The fixed leg BB, is represented 
as beneath the moveable one B C B, or radius, measuring 90°, and the 
lower end of the centre pin, which could not be shown in the wood 
cut, is made to fit the hole or centre in the protractor precisely at the 
same time that a stud or projecting piece of brass, being admitted into 
the long perforation a of the leg B B, the piece becomes steadily at- 
tached to the protractor or semi-circle, as is seen in the Figure. 
The application of this instrument is obvious. The crystal to be 
measured is applied between the compasses, which being thus set, are 
applied to the protractor, and the value of the angle may be read off 
at the fiducial edge of the leg BCB. 
23. The reflective goniometer, invented by Dr. Wollaston [Phil. 
Trans. 1809,) is the most useful of these instruments. It enables us 
to determine the angles even of minute crystals with great accuracy; 
a ray of light reflected from the surface of the crystal being employ- 
ed as radius, instead of the surface itself. Mr. W. Philips has given 
the following description and practical details for the use of this instru- 
Description, 
Application- CRVSTALLIZATIOX. 
meat, in ins introduction to Mineralogy, which, with his permission, 1 
here transcribe. 
Ueitription. 
“ a b Is the principal circle graduated on one edge to half degrees, 
and divided for convenience into two parts of 180° each; (it is gra- 
graduated only in partin the above sketch.) 
“c Is a brass plate, screwed upon, and supported by the pillar d, 
and graduated as a vernier. 
“// Is the axle of the circle a b, and passes through the upper 
part of the two pillars d e, the other ends of which are inserted into a 
wooden base rn. 
“gh Is an axle, enclosed within/f, and turned by means of the 
smallest circle i, which communicates a motion to all the apparatus on 
the left of li, without moving the principal circle a b. 
“k Is a circle, to which is attached the axle of the principal circle. 
If therefore we would move the latter, it wrill be done by moving k; 
and as the axle of the principal circle includes that of the apparatus 
on the left of h, we necessarily give a motion to the whole instrument 
by moving the circle k. 
“ These two movements being understood, let us now suppose that 
rve want to measure a crystal; a rhomboid of carbonate ol lime, for 
instance. 
“Let l be the rhomboid, attached by means of wax to one end of a 
plate of brass n; the other end of the plate being placed in a slit in 
the upper part of the circular brass stem o, which passes through the 
tube p, to which it is so adjusted as to allow of being moved either up 
or down, or circularly, by means of the circle q. 
“ The tube p is fixed to the curved brass plate r, which is attached, 
'but so as to allow of motion, to another curved plate s, by means of a CRYSTALLIZATION. 
pin t, the other end of the latter plate being connected with the con- 
cealed axle g h, to which a motion is given by turning the little circle?’. 
“ By means of the pin t and the tube p, therefore, we have two mo- 
tions, in addition to the two before described as belonging to the axles 
of the instrument. The inner axle, however, may be said to be the 
centre of all the motions. It will therefore be of advantage that the 
rhomboid of carbonate of lime should be placed as nearly on a line 
with that axle as possible : this will be sufficiently adjusted by means of 
the stem o, which admits of being raised or depressed at pleasure. 
“The use of this instrument depends on the reflecting power of the 
polish on the natural planes, or fractured surfaces of minerals: and 
that this is in some cases very powerful, any one may convince himself 
by looking upon a very brilliant plane, held beneath the eye, with its 
edge nearly touching the lower lid, and not far distant from a window ; 
he will then observe the reflection of the bars very distinctly. 
“ Let us then suppose the goniometer, as above represented, to be 
distant from a window from eight to twenty feet. 
“ Let then v be a black line (the use of this is essential) drawn on 
the wainscot between the window and the floor, and perfectly parallel 
with the- horizontal bars of the window. 
“ If, then, the eye be placed almost close to the rhomboid l, a re- 
flection of one of the bars will be seen on one of its planes. 
“ Let us suppose the reflection to be in the direction of the lower 
dotted line on the plane ; and it will be clear that it cannot be paral- 
lel with the bar of the window, not being even with the black line v. 
It must therefore be adjusted. This may perhaps be done by slightly- 
drawing to the left the circle q, which communicates motion by mean# 
of the pin t; or perhaps it may be done by giving a circular motion to 
the stem o. By one of these two motions, or by both, it may certain- 
ly be effected. 
“ If, however, the reflection appears to be like the upper dotted 
line, that is, parallel with the black line v, we must first convince 
selves that it is so, simply by depressing the crystal a little by means of 
moving the little circle i, so as to bring the reflection upon the black 
line. 
“ This being adjusted, which must be done precisely, we then turn 
the crystal, by turning the little circle i, until the reflection of the same 
bar be seen on the next plane, perfectly on a line with and upon the Made- 
line v. 
“ However, in adjusting the second, we may disturb the first reflec - 
tion. By perseverance it will be found that both can be adjusted by 
means of one or other of the movements by the stem o, or the pin t, or 
by the help of both, and a short experience will do away the chief dif- 
ficulties. 
“ Both reflections being precise, we are now, by means of the cir- 
cle k, to turn the principal circle until it is arrested by the stop x on 
the pillar d; it will then be found that one hundred and eighty on the 
principal circle, coincides with o on the vernier. 
“ In doing this, however, we may slightly disarrange the reflections 
On the plane of the crystal, which may be re-adjusted simply by mov- 
ing the little circle i, which will not disturb the principal circle a.b : 
'Applicit'^- CRYSTALLIZATION. 
we must be certain, however, that one hundred and eighty on it forms a 
line with o on the vernier, at the same time that the reflection of the bar is 
seen along the black line. 
“ One movement more, and the measurement will have been made. 
Turn the circle k, keeping the eye almost close to the rhomboid, until 
the reflection of the same bar is seen on the adjoining plane precisely 
upon the black line v, and the operation is completed. 
“ It must then be observed what proportion of the principle circle 
has been moved. Suppose that 105 on it, be now on a line with o on 
the vernier ;—it is the value of the angle. But suppose it to be a lit- 
tle more than 105 and less than 105|: it must then be observed which 
line of the vernier touches, or forms but one line with, another line on the 
principal circle : suppose it to be 5 on the vernier, the angle is then 
105° 5', which is the true value of the obtuse angle of a rhomboid of 
carbonate of lime. 
“ 1 have been the more particular in the above description from be- 
ing aware that the use of this elegant instrument is commonly consider- 
ed to be extremely difficult, and that it is by some supposed, that, in 
taking an angle, it is essential to keep the head in one position, which 
will clearly appear not to be requisite. We may, on the contrary per- 
form any part of the operation, and after the lapse of hours complete 
it. 
“ It may not be amiss to subjoin a few hints connected with its accu- 
rate use. In the first place, it should be observed, that when the cir- 
cle is arrested by the stop x, 180° on it is precisely on a line with o on 
the vernier : this must be exact. 
“ Some difficulty will at first be found in attaching the fragment of 
the crystal to the wax (which must be warmed,) nearly in the requir- 
ed position. In doing this, it will be found of some advantage to hold 
the mineral in such a direction, that the edge between the two planes 
to be measured, shall be in a horizontal position, and, as nearly as pos- 
sible, parallel with the bar of the window. It will be best to begin with 
some substance which is brilliant not more than one-third of an inch in 
diameter, and of which the angles are known. Fragments of transpa- 
rent calcareous spar, or sulphate of barytes, are well adapted. 
“The perfect steadiness of the instrument is essential. A small, 
square, and very solid table, standing firmly, will be useful: but this 
may not be high enough to raise the instrument to the ey e of the ob- 
server without supporting the goniometer, which must be so fixed as 
not to shift its place while moving the circles, or by a casual touch. 
Supposing the table to be of the ordinary height, some support for the 
goniometer a foot above it, will be requisite to elevate it to the eye of 
an observer while sitting. This support should be made in the form 
of a pyramid, with a perfectly flat base, and a truncated summit, on 
which the goniometer may stand, or rather may be fixed, by sliding its 
wooden base m along it; so that, in two opposite places, it shall be con- 
fined by two pieces of wood y y, hollow ed for the purpose of receiv- 
ing it. This pyramid will afford an opening in the upper part for the 
goniometer when out of use, while the lower may be conveniently 
cupied by a drawer.” 
•Further re- 
marks upon its 
accurate use. 24. In following the method above described, (20) Haiiy obtained 
six primitive forms. 
CRYSTALLIZATION. 
Haiiy’a pritfii- 
Uvtt forms. 
i. The cube, parallelopipedon, fyc. 
ii. The tetraedron. 
iii. The octoedron. 
ir. The hexangular prism. 
v. The rhombic dodecaedron. CRYSTALLIZATION. 
ri. The dodecaedron with isoceles triangular facer. 
25. These primitive forms, by further mechanical analysis may be 
reduced to three integral elements. 
i. The parallelopiped, or simplest solid, having six surfaces, paral- 
lel two and two. (24. i.) 
ii. The triangular, or simplest prism, bounded by five surfaces. 
Integral ele- 
ments. 
iii. The tetraedron, or simplest pyramid, bounded by four surfaces. 
(24. ii.) 
26. The secondary forms are supposed to arise from decrements of 
particles taking place on different edges and angles of the primitive 
forms. Thus a cube, having a series of decreasing layers of cubic 
particles upon each of its six faces, will become a dodecaedron, if the 
decrement be upon the edges ; but an octoedron, if upon the angles; 
and by irregular, intermediate, and mixed decrements, an infinite va- 
riety of secondary forms would ensue, as the annexed figures show. 
Theory of se- 
condary forms. CRYSTALLIZATION. 
27. But in crystallography we meet with appearances which Haiiy’s objections to 
theory but imperfectly explains. A slice of fluor spar, for instance, ob- Haib’s th»o- 
tained by making two successive and parallel sections, may be divided y 
into acute rhomboids ; but these are not 
the primitive form of the spar, because by 
the removal of a tetraedron from each ex- 
tremity of the rhomboid an octoedron is ob- 
tained. Thus, as the whole mass of fluor 
may be divided intotetraedra and octoedra, 
it becomes a question which of these forms 
is to be called primitive, especially as nei- 
ther of them can fill space without leav- 
ing vacuities, nor can they produce any 
arrangement sufficiently stable to form the 
basis of a permanent crystal. 
28. To obviate this incongruity, Dr. Wollaston {Phil. Trans. 1813,) 
has very ingeniously proposed to consider the primitive particles as 
spheres, which, by mutual attraction, have assumed that arrangement 
which brings them as near as possible to 
each other. When a number of simi- 
lar balls are pressed together in the 
same plane, they form equilateral trian- 
gles with each other; and if balls so 
placed were cemented together and af- 
terwards broken asunder, the straight lines in which they wmuld be 
disposed to separate, wrould form angles of 60° 
with each other. A single ball, placed any where 
on this stratum, would touch three of the lower 
balls, and the planes touching their surfaces would 
then include a regular tetraedron. A square of 
four balls, with a single ball resting upon the cen- 
tre of each surface, would form an octoedron ; and 
upon applying two other balls at opposite sides of 
Wollaston’s 
theory- CRYSTALLISATION. 
this octoedron, the group will represent the acute 
rhomboid. Thus the difficulty of the primitive 
form of fluor, above alluded to, is done away, by 
assuming a sphere as the ultimate molccula. By 
oblate and oblong spheroids other forms may be 
obtained. 
A sphere the 
ultimate mole* 
Cule. 
29. The subject of crystallization has more lately engaged the atten- 
tion of Mr. J. F. Daniel (Quarterly Journal of Science and the Arts, Vol. 
i.) and his researches have produced some singular confirmations of 
Dr. Wollaston’s hypothesis. If an amorphous piece of alum he im- 
mersed in water and left quietly to dissolve, at the end of about three 
Seeks we shall observe that it has been unequally acted upon by the 
uid : the mass will present the forms of octoedra, and sections cl' oc- 
toedra, as it were carved or stamped upon its surface, as seen in these 
figures: 
Confirmation 
of Wollaston’s 
theory. 
I his appearance is produced when the attraction of the water for 
the solid is nearly counter-balanced by its mechanical texture. The 
crystals formed by this species of dissection are highly curious, from their modifications and relative positions, as the same group presents 
the primitive form as well as its truncations and decrements. Other 
salts yield other figures, and by more complicated chemical action, as 
of acids upon carbonate of lime, the metals, £c., analogous results are 
obtained. Here then, instead of dividing a crystal by mechanical force 
its structure is gradually developed by the process of solution. In these, 
cases two circumstances are particularly remarkable : the crystals are 
different; and their forms vary with the different faces of the original 
mass. In one direction we observe octoedra and sections of octoedra ; 
in another, parallelograms of every dimension, modified with certain 
determinate intersections. 
If, in neither of these positions, we turn the mass upon its axis, the 
same figures will be perceived at every quadrant of a circle ; and, if 
we suppose the planes continued, they will mutually intersect each o- 
ther, and various geometrical solids will be constructed. In this way, 
alum alone furnishes octoedrons, tetraedrons, cubes, four and eight-sid- 
ed prisms either with plain or pyramidal terminations, and rhombic 
parallelopipedons. It is evident, then that no theory of crystallization 
can be admitted, which is not founded upon such a disposition of con-*; 
stituent particles, as may furnish all these modifications, by mere ab-oi 
straction of certain individuals from the congeries, without altering the 
original relative position of those which remain ; and these conditions 
may be fulfilled by such an arrangement of spherical particles, as would 
arise from the combination of an indefinite number of balls endued 
with mutual attraction and no other geometrical solid is adequate to 
the purpose ; and where bodies afford crystals differing from the oc- 
toedral series, an analogous explanation is furnished, by supposing their 
constituent particles to consist of oblate spheroids, whose axes hear 
different proportions to each other in different substances. Hence we 
may also conclude, that the internal structure of all crystals of the{ 
same body is alike, however the external shapes differ. In corrobo-t 
ration of the above hypothesis, we may remark, that the hexaedron is,?, 
of all geometrical figures, that which includes the greatest capacity 
under the least surface. If, therefore, the ultimate particles of crys- 
talline bodies be spheres or spheroids, the greatest possible number in 
the least space will be included in this form. It is probable that the’ 
exterior shape of every crystal is determined by the nucleus first form- r 
ed by a certain definite number of particles, which, by the power of'j 
mutual attraction, overcome the resistance of the medium in whicht 
they were suspended or from which they were separated. This num-I 
her may vary with the solvent, or other contingent circumstances/ 
Four spherical particles, thus united, would balance each other in a 
tetraedral group, six in an octoeidral group, and each would present; 
particular points of attraction to which all subsequent deposits would, 
be directed. Now, let us imagine two nuclei formed in the same so- 
lution, whose axes run in contrary directions ; their increase will con- 
sequently be in contrary directions, and each will attract a particular 
system of particles from the surrounding medium. If these two sys- 
tems should cross each other in their course, a greater number will be 
brought within the sphere of mutual re-action at the point of junction, 
and they ought to arrange themselves in the least possible compass. 
The facts here answer to the theory. If we select any crystals, hav- 
ing others crossing them nearly at right angles, and separate them, the 
points of junction invariably present an hexaedral arrangement. 
CRYSTALLIZATION. 
13 
Several condi- 
tions far a the • 
orjr. 
Internal slrue- 
ture of all crys- 
tals, of the 
same body uni- 
form. 
Probability 
that the exte 
rior shape va- 
ries with and 
depends upon 
the number o£ 
particles unit- 
ed in the nu- 
cleus. 
Their number 
may vary -with 
the solvents, 
&c. 
The plane of 
intersection 
between two 
crystals a hex- 
agon. CRYSTALLIZATION. 
Connexion of 
crystallization 
with chemis- 
ry. 
30. In connexion with chemistry, the theory of crystallization opens 
a new avenue to the science, and frequently enables us to ascertain 
'directly, that which, independent of such aids, could only be arrived 
at by an indirect and circuitous route. We frequently read the che- 
mical nature of substances in their mechanical forms. To the minera- 
logist, an intimate acquaintance with the crystalline forms and modifi- 
cations of natural bodies is essentially requisite. Indeed, the theory 
of crystallization may be considered as one of the great suports of that 
useful branch of natural history, and it is to the indefatigable exertions 
of Haiiy that much of its present perfection is to be referred. In the 
arts, the process of crystallization is turned to very valuable account, 
in the separation and purification of a variety of substances. 
Section II. Heterogeneous Attraction, or Affinity. 
Chemical at- 
traction or affi- 
nity. 
31. We have hitherto considered Attraction as disposing the parti- 
- cles of bodies to adhere so as to form masses or aggregates ; and, in 
many instances, to arrange themselves according to peculiar laws, and 
to assume regular geometrical figures. We are now to regard this power 
as operating upon dissimilar particles ; as presiding over the composi- 
tion of bodies ; and as producing their chemical varieties. This it 
Chemical Attraction, or Affinity. 
32. If, into a glass vessel, exhausted of air, be introduced some sul- 
phur, and copper filings, and heat applied so as to melt the former, it 
will presently combine with the latter. We observe, as the results of 
this attraction between the sulphur and copper, 1. That the substance 
produced has not the intermediate properties of its elements, but that 
it presents new characters. 2. That much heat and light are evolved 
during the mutual action. 3. That sulphur and copper will unite in 
certain proportions only. 
33. In liquids and gases, similar changes of properties may be ex- 
hibited, and, in many cases, a change of form or state results. Thus 
the combination of aeriform bodies produces a solid, as when muriatic 
and ammoniacal gases produce the salt called muriate of ammonia. 
The combustion of gunpowder offers a familiar instance of the con- 
version of solid into aeriform matter. Gases form a liquid, as when 
olefiant gas is mixed with chlorine. Solids also produce liquids, as is 
shown by triturating crystals of Glauber’s salt with nitrate of ammonia : 
and in the action of concentrated solutions of muriate of lime and carbo- 
nate of potassa, liquids form a solid. Liquids produce gases, as when 
one part of nitric acid is mixed with two of alcohol an effervescence 
ensues, and aeriform matter is copiously evolved. 
34. In some cases of combination, the resulting compound differs 
but little from its component parts, and their leading characters are still 
obvious in it. This is especially remarked in solutions of different 
substances in water and other fluids. Salt and sugar dissolved in water, 
retain their saline and sweet tastes, the only physical quality that is 
changed being that of cohesion. 
35. In other cases, the properties of the compound differ essential- 
Result of this 
attraction. 
Solid products 
Raseous 
Liquid. 
The compound 
mayhave some j 
properties si- 
milartoitscon- < 
stituents. < 
Distinct pro- 
perties. CHEMICAL AFFINITSf. 
ly from those of its component parts, and a series of new bodies, pos- 
sessed of distinct and peculiar characters, are produced. Thus, when 
two volumes of nitric oxide gas are mixed with one of oxygen, an 
orange-coloured gas results, very sour, and soluble in water ; whereas, 
the gases before mixture were colourless, tasteless, and insoluble in 
water. 
Such operations are not confined to art: Nature presents them on an 
extended scale ; and, in connexion with the functions of life, renders 
them subservient to the most exalted purposes. 
36. The new chemical powers, that bodies thus acquire in conse- 
quence of combination, are often extremely remarkable, and can only 
be learned by experiment. It frequently happens that inert bodies 
produce inert compounds, and that active substances remain active 
when combined ; hut the reverse often occurs : thus oxygen, sulphur, 
and water, in themselves tasteless and comparatively inert, produce 
sulphuric acid when chemically combined ; and potassa, which is a 
powerful caustic, when combined with sulphuric acid, forms a salt pos- 
sessed of little activity. 
37. The colours, the specific gravity, and the temperature of bodies 
are also commonly altered by chemical action. Thus the blue infusion 
obtained by macerating violets in warm water is rendered red by acids, 
green by alcalis, and its colour is wholly destroyed by chlorine. When 
equal parts of sulphuric acid and water are mixed, the resulting liquid 
has a specific gravity much above the mean ; the temperature is also 
much increased ; and ignition frequently attends chemical action. (32.) 
38. As chemical action takes place among the ultimate or constituent ■ 
elements of bodies, it must obviously he opposed by the cohesion of] 
their particles, and chemical attraction is often prevented by mechanic-5 
al aggregation. A piece of the metal antimony, put into the gas called 
chlorine, is only slowly and superficially acted upon ; but if the mecha- 
nical aggregation be previously diminished, by reducing the metal to 
powder, it in that state rapidly unites with the gas, and burns the instant 
that it is introduced. 
39. Heat increases the chemical energies of bodies. Its effects are 
sometimes only referable to the diminution of adhesion by expansion or 
liquefaction ; but in other cases they are peculiar and complicated and 
probably concerned in modifying the electrical energies of the acting 
substances. 
40. Different bodies are possessed of different attractive powers, and 
if several be brought together, those which have the strongest mutual: 
affinities enter first into union. Thus, if nitric acid he poured upon a1 
mixture of lime and magnesia, it dissolves the former in preference to 
the latter earth. The knowledge, of this fact, enables us to separate 
bodies when united, or to perform the process of decomposition. Thus 
if we add an aqueous solution of lime to a solution of magnesia in nitric 
acid, the latter earth is thrown down or precipitated, and the lime occu- 
pies its place in the acid. 
41. Upon this principle tables of attraction have been constructed, 
the substance whose affinities are to be represented being placed at the 
head of a column, and the bodies with which it combines beneath it, in 
the order of their respective attractions (see History of Chemistry, p. 
78.;) thus the affinity of sulphuric acid for several bases would be 
shewn as follows: 
Other changes 
produced by 
chemical ac- 
tion. 
Chemical ac- 
tion takes 
place between 
elementary 
matteris there- 
fore opposed te 
simple cohe- 
sion. 
Attraction of 
aggregation 
acts in opposi- 
tion. 
Caloric pro- 
motes Chens, 
action. 
Simple or elec- 
tive attractio*. CHEMICAL AFFINITY. 
Sulphuric acid 
Baryta. 
Strontia. 
Potassa. 
Soda. 
Lime. 
Magnesia. 
Ammonia. 
From this table it would appear that baryta separates sulphuric acid 
from its compounds with all the inferior substances, and that ammonia 
is separated by all that are above it; there are, however, many cir- 
cumstances which interfere with the usefulness and accuracy of such 
tables, and in some cases there are anomalies in the mutual agencies of 
bodies which wholly subvert the usual order of arrangement. One of 
these has been pointed out by Mr. R. Phillips,—(Journal of Science, 
and the Arts, Vol. i., p. 80.) He found that on boiling carbonate of 
baryta in a solution of sulphate of potassa, sulphate of baryta and car- 
bonate of potassa were formed; and he also found that, on reversing 
the experiment, by boiling sulphate of baryta in solution of carbonate 
of potassa carbonate of baryta and sulphate of potassa were produced. 
42. Decomposition is effected under a variety of circumstances, and 
by many methods ; but it is commonly described by chemists as Simple 
and Complex, or Single and Double. 
43. In cases of simple attraction or affinity, one body separates 
another from its combination with a third. Thus, when potassa is ad- 
ded to a solution of sulphate of zinc (composed of sulphuric acid and 
oxide of zinc,) the oxide of zinc is separated, and sulphate of potassa 
is produced. 
44. In cases of double decomposition, two new compounds are pro- 
duced ; as when a solution of nitrate of baryta, is mixed with a solu- 
tion of sulphate of soda, the results are a precipitate of sulphate of 
baryta, and a solution of nitrate of soda. 
45. These cases of double decomposition are sometimes convenien- 
tly illustrated by diagrams, which may either be constructed so as mere- 
ly to show the result of the change, or where required they may also 
exhibit the composition of the acting bodies. In the case just alluded 
to, the substances before mixture are shown by parallel lines, and af- 
ter mixture by diagonal lines. 
Single decom- 
p»sitioa. 
Double de- 
composition. 
Nitric Acid 
Baryta. 
Sulphuric Acid_ 
_ Soda. CHEMICAL AFFINITY. 
Or a more complete view of the change is given in the following dia- 
gram, where the bodies before mixture are placed upon the outside of 
the perpendicular lines ; their component parts are shown within 
them ; and the new results on the outside of the horizontal lines. 
Nitrate of Soda. 
Nitric 
Acid 
Soda. 
Nitrate of 
Baryta. 
Sulphate 
. of Soda. 
Baryta. 
Sulphuric 
Acid. 
Sulphate of Baryta. 
46. It is obvious, from the uniform results of chemical action that, 
affinity must he governed by certain definite laws, by which its results 
are determined, and upon which its uniformity depends. Attention: 
was first called to this subject by Mr. Higgins in 1789,—([Comparative 
View of the Phlogistic and Antiphlogistic Theories.) He conceived 
that chemical attraction only prevailed between the ultimate particles 
of simple elementary matter, and between compound atoms ; and, in 
applying this idea to chemical theory, he expressed by numbers the re- 
lative forces of attraction subsisting between the diff erent kinds of ulti- 
mate particles and atoms of matter. 
These views were subsequently extended and improved by Mr. 
Dalton, and have since engaged the attention of some ol the most emi- 
nent chemical philosophers ; among whom we may enumerate Gay- 
Lussac and Berzelius, Davy, Wollaston, and Thomson. 
46. The atomic doctrine or theory of definite proportionals, has been 
much blended with hypothetical views ; but it will be most satisfacto- 
rily and usefully considered as an independent collection of facts.* 
When bodies unite so as to form one compound only, that compound 
always contains the same relative proportions of its components ; and 
where two bodies unite in more than one proportion, the second, third, 
4*c., proportions are multiples or divisors of the first. This law is 
well exhibited in the combinations of gaseous bodies. These are seen 
to unite in simple ratios of volume. Water is composed of hydrogen 
and oxygen, and 1 part by weight of the former gas, unites to 8 of the 
Chemical affi- 
nity governed 
by definite 
laws. 
Higgins’ idea. 
Made a sys- 
tem or theory 
by Dalton. 
Definite Pro- 
portion. 
* See note at the end of the rolume. 18 
CHEMICAL AFFINITY. 
latter. The specific gravity of hydrogen compared with that of oxy- 
gen, is as 1 to 15 ; it is obvious, therefore, that one volume of hydro- 
gen unites to half a volume of oxygen, and that the composition of 
water will be represented by weight and volume thus : 
1 
Oxygen. 
8 
Hydrogen. 
Muriatic acid gas consists of 1 part by weight of hydrogen and 36.0 
by weight of chlorine. The relative specific gravities of these gases are 
as 1 to 36.0. It is obvious, therefore, that they combine in equal vo- 
lumes, and that muriatic acid gas may be thus represented : 
1 
36.0 
Hydrogen. 
Chlorine. 
Carbonic acid unites to potassa in two proportions, and forms two de- 
finite compounds. In the one, 70 parts of potasso are combined with 
30 of carbonic acid ; in the other, 70 of potasso are united to 60 of 
carbonic acid. 
Lead combines with oxygen in three proportions ; the first compound 
consists of 100 lead -j- 8 oxygen ; the second, of 100 + 12 ; the third, 
of 100 -{- 16. 
47. All cases of chemical combination, in which the qualities of the 
component parts are no longer to be detected in the compound, or in 
which a neutral body is produced, are obedient to these laws of union : 
But in some instances bodies may be said to unite in all proportions, as 
water and alcohol, fyc. Other bodies combine in all proportions up to 
a certain point only, and beyond that, combination no longer ensues. 
Thus water will take up successive portions of common salt, until at 
length it refuses to take up more, or is saturated; and this always oc- 
curs when the water has dissolved a definite weight of the salt. 
48. The term neutralization is applied to cases in which bodies mu- 
tually disguise each other’s properties, as is especially exemplified in 
the union of acids with alcalis ; as of sulphuric acid, for instance, with 
solution of potassa. The acid reddens violet juice, and is sour. The 
potassa converts the blue to green, and is acrid. If the acid solution 
be gradually added to the alcaline, we shall find that, at a certain point, 
the taste will neither be acid nor acrid, but slightly saline and bitter, 
nor will there be any effect produced upon the vegetable blue. Thus 
the acid is neutralized by the alcali, and the compound has been term- 
ed a neutral salt. 
49. When we have ascertained the proportion in which any two or 
more bodies of one class, a b c, neutralize another body a: of a differ- 
ent class, it will be found that the same relative proportion of a b c, 
#-c., will be required to neutralize any other body of the same classes 
x. Thus, since 100 parts of sulphuric acid, and 68 (omitting fractions,) 
of muriatic acid, neutralize 118 of potassa, and since 100 of sulphuric 
Saturation. 
Neutraliza- 
tion. neutralize 71 of lime, we may infer that 68 of muriatic acid will also 
neutralize 71 of lime. 
50. If the quantities of two bodies A and B, that are necessary to 
saturate a given weight of a third body, be represented by q and r, 
these quantities may be called equivalents. Thus in the above exam- 
ple (49,) 100 parts of sulphuric acid and 68 of muriatic acid, are equi- 
valents of each other. A column of equivalent numbers, of great use 
in chemical calculations, will be found in the tables inserted in another 
part of this work. By adapting a table of this sort to a moveable scale, 
on the principle of Gunter’s sliding rule, Dr. Wollaston has construct- 
ed a logornetric scale of chemical equivalents, which is capable of solving 
with great facility many problems of chemistry.—Phil. Trans. 1814. 
51. By prosecuting chemical analysis, we arrive at a certain num- 
ber of principles or elements; that is, of bodies which have not hitherto 
been decomposed. 
The nature of compound bodies is demonstrated by two kinds of 
proof—synthesis and analysis. Synthesis consists in effecting the che- 
mical union of two or more bodies, which by analysis are again 
separated from each other. The term 'proximate analysis has been 
applied to the separation of two bodies which are themselves com- 
pounded ; and ultimate analysis to the farther separation of these com- 
pounds into their components. The composition of blue vitriol is syn- 
thetically demonstrated by uniting sulphuric acid to oxide of copper— 
analytically by separating these proximate elements from each other. 
But the sulphuric acid consists of sulphur and oxygen; and oxide of 
copper consists of copper and oxygen : consequently, we should say 
that the ultimate component parts of blue vitriol are copper, sulphur, 
and oxygen. 
CHEMICAL AFFINITr. 
Equivalents. 
Modes of as- 
certaining tlit 
Composition 
of bodies. 
Section III. Heat. 
52. Heat may be considered as a power opposed to attraction, for 
it tends to separate the particles of bodies ; and whenever a body is 
heated, it is also expanded. Expansion is the most obvious and familiar 
effect of heat; and it takes place, though in different degrees, in all 
forms of matter. Solids are the least expansible,—liquids expand more 
readily than solids,—and gasses or aeriform bodies more than liquids. 
53. When a body has been expanded by heat, it regains its former 
dimensions, or contracts, when cooled to its former temperature. 
54. Different bodies expand differently when equally heated. The 
metals are the most expansible solids ; but among them, zinc expands 
more than iron, and iron more than platinum. 
The following table shows the relative expansibility of some of the 
metals, when their temperature is raised from the freezing to the boiling 
point of water. 
Calorie in op- 
position to at- 
traction. 
It expands 
most bodies. 
Bodies posses* 
different pow- 
ers of expan- 
sion. HEAT. 
Temperature. 
Platinum. 
Steel. 
Iron. 
32° 
120000 
120000 
120000 
212° 
120104 
120147 
120151 
Temperature. 
Copper. 
Brass. 
Tin. 
32® 
120000 
120000 
120000 
212° 
120204 
120230 
120290 
Temperature. 
Lead. 
Zinc. 
32° 
120000 
120000 
212° 
120345 
120360 
Table of the 
expansibility 
of some me- 
tals. 
55. Liquids differ also in their relative expansibilities : ether is 
more expansible than spirit of wine, and spirit more than water, and 
water more than mercury. Those liquids are generally most expansi- 
ble which boil at the lowest temperature. 
The following Table shows the fate of expansion of several liquids : 
Temp. 
Mercury. 
Linseed 
Oil. 
Sulphuric 
Acid. 
Nitric 
Acid. 
Water. 
Oil of 
Turpent. 
Alchohol. 
32° 
100000 
100000 
— 
— 
— 
— 
100000 
40 
100081 
— 
99752 
99514 
— 
— 
100539 
50 
100183 
— 
100000 
100000 
100023 
100000 
101105 
60 
100304 
— 
100279 
100486 
100091 
100460 
101688 
70 
100406 
— 
100558 
100990 
100197 
100993 
102881 
80 
100508 
— 
100806 
101530 
100332 
101471 
102890 
90 
100610 
— 
101054 
102088 
100694 
101931 
103517 
100 
100712 
102760 
101317 
102620 
100908 
102446 
104162 
110 
100813 
— 
101540 
103196 
— 
102943 
— 
120 
100915 
— 
101834 
103776 
101404 
103421 
— 
130 
101017 
— 
102097 
104352 
— 
103954 
— 
140 
101119 
— 
102320 
105132 
— 
104573 
— 
150 
101220 
— 
102614 
— 
102017 
— 
— 
160 
101322 
— 
102893 
— 
— 
— 
— 
170 
101424 
— 
103116 
— 
— 
— 
— 
180 
101526 
— 
103339 
— 
— 
— 
— 
190 
101628 
— 
103587 
— 
103617 
— 
— 
200 
101730 
— 
103911 
— 
— 
— 
— 
212 
101835 
107250 
— 
— 
104577 
— 
— 
Table of the 
expansion of 
several fluids. 
Rate of ex- 
pansion a- 
mong pure ga- 
tes. “ 
66. In all pure gaseous bodies, the rate of expansion for similar in- 
crease of temperature is similar : 100 measures of air, when heated 
from the freezing to the boiling point of water, suffer an increase in 
bulk =37,5 parts at mean pressure. BEAT. 
21 
The experiments of Gay-Lussac have proved that steam, and all va- 
pours are subject to laws of expansion similar to those of air,—hence the 
following T able, showing the changes of bulk suffered by 100000 parts of 
air at all temperatures between 32® and 212°, will apply equally to all 
gases and vapours, and will often be found useful to the practical chemist. 
Temper. 
Bulk. 
Temper. 
Bulk. 
Temper. 
Bulk. 
32<> 
100000 
59° 
105616 
86° 
111232 
33 
100208 
60 
105824 
87 
111440 
34 
100416 
61 
106032 
88 
111648 
35 
100624 
62 
106240 
89 
111856 
36 
100833 
63- 
106448 
90 
112064 
37 
101040 
64 
106656 
91 
112272 
38 
101248 
65 
106864 
92 
112480 
39 
101459 
66 
107072 
93 
112688 
40 
101666 
67 
107280 
94 
112896 
41 
101872 
68 
107488 
95 
113104 
42 
102080 
69 
107696 
96 
113312 
43 
102290 
70 
107904 
97 
113520 
44 
102496 
71 
108112 
98 
113728 
45 
102708 
72 
108320 
99 
113936 
46 
102916 
73 
108528 
100 
114144 
47 
103124 
74 
108736 
110 
116224 
48 
103333 
75 
108944 
120 
118304 
49 
103536 
76 
109152 
130 
120384 
50 
103749 
77 
109360 
140 
122464 
51 
103952 
78 
109568 
150 
124544 
52 
104166 
79 
109776 
160 
126624 
53 
104368 
80 
109984 
170 
128704 
54 
104576 
81 
110192 
180 
130784 
55 
104791 
82 
110400 
190 
132864 
56 
104992 
83 
110608 
200 
134944 
57 
105200 
84 
110816 
210 
137024 
58 
105408 
85 
111024 
212 
137440 
Table of ex- 
pansion for all 
gases and va- 
pours. 
57. The expansion of liquids is not equable for equal additions of 
•heat at different temperatures. Thus the addition of 5® of heat to al- 
cohol at 40°, will produce a less relative increase of bulk than the same 
addition of heat to alcohol of 100° ; and in general, the nearer a liquid 
approaches its boiling point, the greater is it expansibility. Those li- 
quids therefore appear most equably expansible which have the highest 
boiling points, and hence one of the great advantages of mercury, as 
will presently be seen, in constructing thermometers. 
58. As heat increases the bulk of all bodies, it is obvious that change 
of temperature is constantly producing changes in their density or 
specific gravity, as may be easily demonstrated in fluids where there 
is freedom of motion among the particles. If I apply heat to the bot- 
tom of a vessel of water, the heated part expands and rises, while a 
cold or denser stratum occupies its place. In air, similar currents are 
continually produced, and the vibratory motion observed over chim- 
ney pots, and slated roofs which have been heated by the sun, depends 
Fluids with 
the highest 
boiling point 
expand most, 
equably. 
Specific gravi- 
ty altered by a 
change of tera- 
peratur*. 22 
upon this circumstance : the warm air rises, and its refracting power 
being less than that of the circumambient colder air, the currents 
are rendered visible by the distortion of objects viewed through them. 
59. The ventilation of rooms and buildings, can only he perfectly effect- 
ed by suffering the heated and foul air to pass off through apertures in the 
ceiling, while fresh air, of any desired temperature, is admitted from be- 
low. Various contrivances have been resorted to, to prevent the passage 
of cold air from above downwards through the ventilator, which can only 
be completely effected by keeping the ventilating tubes at a higher tem- 
perature than the surrounding air ; heating them, for instance, by steam ; 
passing them through a tire ; or placing a lamp beneath them, of suffi- 
cient dimensions to cause a strong current upwards : upon the latter 
principle, the gas chandelier in Covent-garden theatre being placed un- 
der a large funnel, which passes through the roof into the outer air, ope- 
rates as a very powerful ventilator, all its own heat and smoke passing off 
with a large proportion of the air of the house.—Quarterly Journal, v. 
60. There is only one strict exception to the general law of expansion 
by heat, and contraction by cold ; this is in the case of water, which ex- 
pands considerably when it approaches its freezing point. Water has at- 
tained its maximum of density at 40°, and if it be cooled below 40° it ex- 
pands as the temperature diminishes, as it does Avhen heated above 40’° ; 
and the rate of this expansion is equal for any number of degrees above or 
below this maximum of density, so that the bulk of water at 32° and at 48° 
will be the same. Accordingly, if two thermometer tubes, one contain- 
ing spirit of wine, and the other water, be immersed into melting snow, 
the former will sink till it indicates 32° ; hut the latter when it has at- 
tained 40° begins to expand, and continues so to do till it freezes. 
This anomaly in respect to water is productive of very important 
consequences, in preserving the depths of rivers and lakes of a tem- 
perature congenial to their inhabitants. 
61. There are many liquids which suffer considerable expansion in pas- 
sing into the solid state. This is the case w ith the greater number of sa- 
line solutions, and remarkably with water ; it seems connected with the 
phenomena of crystallization, and is referable to a new arrangement of 
particles. That the force Avith which water expands in the act of freezing, 
is very considerable, is shown by the rupture of leaden and iron pipes in 
which it is suffered to freeze. Dr. Thomson has shoAvn that water in 
freezing suffers a much greater expansion than when heated from the 
freezing to the boiling point; for the specific gravity of water at 60° 
being = 1, that of ice at 32° is only 0.92. Of the metals, Reaumur 
found that cast-iron, bismuth, and antimony, Avhen expanded in becom- 
ing solid ; the rest contracted. 
62. If we mix equal quantities of the same fluid at different tempera- 
ratures,Jthe cold portion will expand as much as the hot portion contracts, 
and the resulting temperature is the mean; so that it appears, that as 
much heat as is lost by the one portion is gained by the other. Upon 
this principle, thermometers are constructed. A common thermometer 
consists of a tube terminated at one end by a bulb, and closed at the other. 
The bulb and part of the tube are filled Avith a proper liquid, generally 
mercury, and a scale is applied, graduated into equal parts. W henever 
this instrument is applied to bodies of the same temperature, the mercu- 
ry, being similarly expanded, indicates the same degree of heat. 
63. In dividing the scale of a thermometer, the tAvo fixed points usually 
resortedto are the freezingand boilingof Avater,Avhich always take place at 
HEAT. 
Exception to 
the law of ex- 
pansion by ca- 
loric. 
An apparent ( 
•bject in this 
anomaly. ] 
Water ex- ‘ 
pands more in j 
freezing than j 
it does when 
heated from 1 
the freezing to l 
the boiling * 
point. f 
Principles up- 1 
on which the r- , 
mometers are * 
Constructed, j the same temperature, when under the same atmospheric pressure. The 
intermediate part of the scale is divided into any convenient number of 
degrees ; and it is obvious, that all thermometers thus constructed will 
indicate the same degree of heat when exposed to the same temperature. 
Inthecentigrade thermometer, this space is divided into 100° ; the freez- 
ing of water being marked 0°, the boiling point 100°. In this country 
we use Fahrenheit’s scale, of which the 0" is placed at 32° below the 
freezing of water, which, therefore, is marked 32°, and the boiling point 
212°, the intermediate space being divided into 180°. Another scale 
is Reaumur’s ; the freezing point is 0°, the boiling point 80". These 
are the principal thermometers used in Europe. 
64. Each degree of Fahrenheit’s scale is 
equal to £ of a degree on Reaumur’s : if, there- 
fore, the number of degrees on Fahrenheit’s 
scale, above or below the freezing of water, be 
multiplied by 4, and divided by 9, the quotient 
will be the corresponding degree of Reaumur. 
HEAT. 
23 
Fahrenheit. Reaumur, 
68®—32°= 36X4=1444- 9=16® 
212®—32°=180X4=7204-9=80® 
Rules for com- 
paring the or- 
dinary ther- 
mometers. 
To reduce the degrees of Reaumur to those 
of Fahrenheit, they are to be multiplied by 9, 
and divided by 4. 
Reaumur. Fahrenheit. 
16° X 9= 1444-4= 36®-{-32° = 68 
80° X 9=720-j-4=180 +32®=212 
Every degree of Fahrenheit is equal to £ of a 
degree on the centigrade scale ; the reduction, 
therefore, is as follows : 
Fahrenheit. Centigrade. 
212—32=180X5=9004-9=100°. 
Centigrade. Fahrenheit. 
100 X 9=900-j-5= 180+32=212® 
The annexed is a comparative table of the 
different thermometrical scales, including de 
Lisle’s, in which the graduation commences 
with the boiling point which is marked 0®, and 
the freezing 150®. 24 
IIEAT. 
65. When a thermometer is intended to measure very low tempe- 
ratures, spirit of wine is employed in its construction, as that fluid 
has never been frozen, whereas the low temperature at which it boils, 
renders it unfit for measuring high temperatures. Quicksilver will in- 
dicate 500°, but freezes at 40°. 
66. Air is sometimes resorted 
to as indicating very small chang- 
es of temperature ; and of air ther- 
mometers, that described by Pro- 
fessor Leslie (Experimental In- 
quiry into the Nature and Propa- 
gation of Heat, by John Leslie, 
London, 1804, p. 9, under the 
name of the differential Thermome- 
ter, is the best. It consists of two 
large glass bulbs containing air, 
united by a tube twice bent at right 
angles, containing coloured sul- 
phuric acid. When a hot body 
approaches one of the bulbs, it 
drives the fluid towards the other. 
The great advantage of this instru- 
ment in delicate experiments is 
that general changes of the atmos- 
phere’s temperature do not affect 
it, but it only indicates the differ- 
ence of temperature between the 
two balls. 
67. Sometimes a simpler form of the air thermometer is 
employed, consisting merely of a tube with a bulb at one 
extremity, the other end being open and immersed into co- 
loured water, which by expelling a portion of air from the 
tube by heat, is made to stand at any convenient height: 
the liquid in the tube descends and rises on heating and 
cooling the air in the bulb. 
68. The relative quantities of heat which different bodies 
in the same state require to raise them to the same ther- 
mometric temperature, is called their specific heat, and 
those bodies which require most heat are said to have the 
greatest capacity for heat. That the quantity of heat in 
different bodies of the same temperature is different, was 
first shown by Dr. Black, in his lectures at Glasgow in 
1762. 
69. It has been stated as a proof of the accuracy of the thermome- 
ter, that equal volumes of the same fluid, at different temperatures, 
give the arithmetical mean, on mixture. Thus, the temperature of a 
pint of hot and a pint of cold water is, after mixture, as near as possi- 
ble half-way between the extremes. The cold water being of a tem- 
perature of 50°, and the hot of 100°, the mixture raises the thermom- 
Advantage of 
spirit of wine. 
Leslie’s differ- 
ential ther- 
mometer of 
air. 
Simple air 
thermometer. 
Specific calo- 
ric. 
Froof of the 
accuracy of 
Siarmometers. HEAT. 
eter to 75®. But if a pint of quicksilver at 100° be mixed with a pint 
of water at 50°, the resulting temperature is not 75°, but 70° ; so that 
the quicksilver has lost 30°, whereas the water has only gained 20°. 
Hence, it appears, that the capacity of mercury for heat is less than 
that of water ; and if the weight of the two bodies be compared, which 
are as 13.3 to 1, their capacities, will be to each other as 19 to 1. 
70. In cases where the specific heat of bodies is to be ascertained, 
it is convenient that water should be the standard of comparison, or= v 
1. The following is a general formula for determining the specific*' 
heat of bodies, from the temperature resulting from the mixture of 
two bodies at unequal temperatures, whatever be their respective 
quantities. Multiply the weight of the water by the difference be- 
tween its original temperature, and that of the mixture : also, multiply £ 
the weight of the other liquid, by the difference between its tempera-tt 
ture and that of the mixture : divide the first product by the second,*0 
and the quotient will express the specific heat of the other substance, 
that of water being = 1. Thus, 20 ounces of water at 105°, mixed 
with 12 ounces of spermaceti oil at 40°, produce a temperature of 90°. 
Therefore, multiply 20 by 15 (the difference between 105 and 90) = 
300. And multiply 12 by 50 (the difference between 40 and 90) = 
600. Then 300, -f- 600, =i, which is the specific heat of oil ; that 
is, water being = 1, oil is = 0,5. 
71. The capacities of bodies for heat have considerable influence 
upon the rate at which they are heated and cooled. Those bodies 
which are most slowly heated and cooled have generally the greatest 
capacity for heat. Thus, if equal quantities of water and quicksilver 
be placed at equal distances from the fire, the quicksilver will be more j 
rapidly heated than the water, and the metal will cool most rapidly t 
when carried to a cold place. Upon this principle, Professor Leslie 
ingeniously determined the specific heat of bodies, observing their 
relative times of cooling a certain number of degrees, comparatively 
with water, under similar circumstances. 
M. M. Petit and Dulong have published some important researches A 
on the subject of specific heat, which render it probable that the atoms * 
of all simple substances have exactly the same capacities for heat. \ 
72. Lavoisier and La Place endeavoured to ascertain the specific1 
heat of bodies by the relative quantities of ice which they were capa- 
ble of thawing, during cooling : thus, if a pint of water in cooling from 
212° to 32° melted a pound of ice, and a pint of oil in passing through, 
the same range of temperature only gave out heat enough to thaw half 
a pound of ice, it was concluded that the specific heat of water being= 
1, that of the oilwas=0.5. The instrument which they employed in 
these researches, and which is fully described in Lavoisier’s Elements of 
Chemistry, is not however, susceptible of accuracy, for Mr. Wedgwood 
has shown that it is scarcely possible to separate the water from the 
ice.—Phil. Trans. Vol. lxxiv. 
73. The capacity of gases and vapours differs with the nature of the 
gas, and with its density. In gases, dilatation produces cold, and com- 
pression excites heat. A thermometer suspended in the receiver of 
the air-pump sinks during exhaustion, and sudden compression of air! 
produces heat sufficient to inflame tinder. In liquids, too, condensa-1 
tion diminishes capacity for heat; hence the mixture of spirit and wa- 
ter, and of sulphuric acid and water evolves heat. The increased car 
Water the 
standard for 
specific heat- 
Formula for 
determining 
the specific ca- 
loric of bodies* 
Leslie’s 
thod. * 
All atoms 
seem to have 
the same ca- 
pacity for car 
loric 
Lavoisier’s 
method. 
f Dilatation of 
gases produce? 
’ cold comprei- 
_ sion heat.. MEAT. 
pacity which air acquires by rarefaction has its influence in modifying 
natural temperatures. The air, becoming rarer as it ascends, absorbs 
its own heat and hence becomes cold in proportion as it recedes from 
the earth’s surface : thus moisture, rain, or snow, are thrown down on 
the mountain-tops. 
74. When different bodies are exposed to the same source of heat, they 
suffer it to pass through them with very different degrees of velocity or 
they have various conducting powers in regard to heat. Among solid bo- 
dies, metals are the best conductors ; and silver, gold, and copper are 
better conductors than platinum, iron, and lead. Next to the metals, we 
may, perhaps, place the diamond, and topaz ; then glass ; then siliceous 
and hard stony bodies in general; then soft and porous earthy bodies, and 
wood; and lastly, down, feathers, wool, and other porous articles of 
clothing. 
75. To compare the relative conducting powers of metals, and some 
other solids, small cones of the different substances may be used about 
’three inches high, and half an inch in diameter at their bases : these 
may be tipped at the apex with a small piece of wax, and being placed 
on a heated metallic plate, will indicate the conducting powers by the 
relative times required to fuse the wax, which will be directly, as the 
power of conducting heat. 
The difference between the conducting power of the diamond and 
rock crystal or glass, is shown by applying the tongue to those sub- 
stances, when the former feels colder than the latter. 
From the experiments of Professor Mayer, of Erlangen, (Annales de 
Chimie, tom. xxx.) it would appear that the conducting powers of dif- 
ferent woods is in some measure inversely as their specific gravities, 
as shown by the following table, water being assumed as = 1. 
Conducting 
power ol bo- 
dies for calo- 
ric. 
Method of de- 
termining this 
power. 
Water 
Conducting’ Power. 
10 
Specif. Grav, 
. 1.000 
Ebony Wood 
. . . . 
. 21.7 
. 1.054 
Apple tree 
. . . . 
. 27.4 
. 0.639 
Ash 
• • • • 
. 30.8 
. 0.631 
Beech 
.... 
. 32.1 
. 0.692 
Hornbeam 
.... 
. 32.3 
. 0.690 
Plum tree 
, , , t 
. 32.5 
. 0.687 
Elm 
.... 
. 32.5 
. 0.646 
Oak 
• • • • 
. 32.6 
. 0.668 
Pear tree 
.... 
. 33.2 
. 0.603 
Birch 
.... 
.34.1 
. 0.608 
Silver fir 
, , , , 
. 37.5 
. 0.495 
Alder 
• • • • 
. 38.4 
. 0.484 
Scotch fir 
• • • • 
. 38.6 
. 0.408 
Norway Spruce 
. 38.9 
. 0.447 
Lime 
• . • . 
. 39.0 
. 0.408 
Table of con- 
ducting pow- 
ers. 
Count Ruinford’s experiments on the conducting power of several 
substances used as clothing offer some interesting results, (Phil. Trans. 
1792.) He found that a thermometer enclosed in a tube and bulb of the 
same shape,but large enough to allow of an inch vacant space between 
the two, being previously heated, required 576 seconds to cool 135°. 
When 16 grains of lint were diffused through the confined air, it took 
1032 seconds to undergo the same change of temperature ; and 1305 se- 
conds with the same weight of Eider-down. The compression of floccu- 
Conducting 
power of cloth- 
ing substances. HEAT 
lent substances to a certain extent, renders them still interior conductors: 
thus, when the space which in the above experiments contained 16 
grains of Eider-down was tilled with 32, and then with 64 grains, the 
times required for the escape of 60 degrees of heat were successively 
increased from 1305'' to 1472" and 1615''. 
On the other hand to show the effect of mere texture, similar com- 
parative trials were made of the conducting powers of equal weights of 
raw silk, of ravelings of white taffeta, and of common sewing silk, of 
which the first has the finest fibre, the second less fine, and the third 
from being twisted and harder is much coarser. The difference be- 
tween these three modifications of the same substance is very striking 
the raw silk detaining the heat for 1284", the taifeta ravelings 1169", 
and the silk thread only 917'.—Aikin’s Diet. Art. Caloric. 
76. Liquids and gases are very imperfect conductors of heat, and 
heat is generally distributed through them by a change of specific gra- 
vity, as before stated (58. 59.) 
If we apply heat to the upper surface of any fluid, it will with great 
difficulty make its way downwards. Count Rurnford considered fluids 
as non-conductors of heat; but the more accurate researches of Dal- 
ton, Hope, Murray, (System of Chemistry, Vol. i.,) and Thomson, 
(System of Chemistry, Vol. i.,) have demonstrated that they do conduct, 
though very imperfectly. 
Thus, if we carefully pour hot oil upon water in a tall glass jar with 
delicate thermometers placed at different distances under the surface, 
it will be found that those near the heated surface indicate increase oi 
temperature : it might here be said that the heat was conducted by the 
sides of the jar, and so communicated to the water ; to obviate such ob- 
jection, Mr. Murray made the experiment in a vessel of ice, which be- 
ing converted into water at 32°, cannot convey any degree of heat 
above 32° downwards ; yet the thermometers were affected, as in the 
former trial. 
Experiments on the conducting power of air are complex and diffi- 
cult, and the results hitherto obtained are unsatisfactory. They are 
interfered with by several circumstances hereafter to be noticed, and 
especially by radiation. 
77. The different conducting powers of bodies in respect to heat, 
are shown in the application of wooden handles to metallic vessels ; or 
a stratum of ivory or wood is interposed between the hot vessel and 
the metal handle. The transfer of heat is thus prevented. Heat is 
confined by bad conductors ; hence clothing for cold climates consists 
of woolen materials ; hence, too, the walls of furnaces are composed 
of clay and sand. Confined air is a very bad conductor of heat; hence 
the advantage of double doors to furnaces, to prevent the escape oi 
heat; and of a double wall, with an interposed stratum of air, to an 
icehouse, which prevents the influx of heat from without. 
78. From the different conducting powers of bodies in respect to 
heat, arise the sensations of heat and cold experienced upon their ap- 
plication to our organs, though their thermometric temperature is simi- 
lar. Good conductors occasion, when touched, a greater sensation oi 
heat and cold than bad ones. Metal feels cold because it readily car- 
ries off' the heat of the body ; and we cannot touch a piece of metal 
immersed in air of a temperature moderate to our senSO. 
79. Heat has great influence on the forms or states of bodies. 
When we heat a solid, it becomes fluid or saseous : and liuuids are 
• Effect of tex- 
nture. 
Liquids and 
gas imperfect 
conductors. 
Sensations of 
heat and cold. 28 
Forms and 
states of bo- 
dies influen- 
ced by calo- 
HEAT. 
converted into aeriform bodies or vapours. Dr. Black investigated 
this effect of heat with singular felicity, and his researches rank among 
the most admirable efforts of experimental philosophy, (Black’s Lec- 
tures, edited by John Robison, LL.D.) During the liquefaction of bo- 
dies, a quantity of heat is absorbed, which is essential to the state of 
fluidity, and which does not increase the sensible or thermometric 
temperature. Consequently, if a cold solid body, and the same body 
hot and in a liquid state, be mixed in known proportions, the tempera- 
ture after mixture will not be the proportional mean, as would be the 
case if both were liquid, but will fall short of it; much of the heat of 
the hotter body being consumed in rendering the colder solid, liquid, 
before it produces any effect upon its sensible temperature. 
80. Equal parts of water at 32°, and of water at 212° will produce 
on mixture a mean temperature of 122°. But equal parts of ice at 
32°, and of water at 212°, will only produce (after the liquefaction of 
the ice) a temperature of 52°, the greater portion of the heat of the 
water being employed in thawing the ice, before it can produce any 
rise of temperature in the mixture. To heat thus insensible or combin- 
ed, Dr. Black applied the term latent heat. The actual loss of the 
thermometric heat in these cases was thus estimated ; a pound of ice 
at 32° was put into a pound of water at 112° ; the ice melted, and the 
temperature of the mixture was 32°. Here the water was cooled 
140°, while the temperature of ice was unaltered ; that is, 140° of 
heat disappeared, their effect being not to increase temperature, but to 
produce fluidity. 
81. The same phenomena are observable in all cases of liquefac- 
tion, and we produce artificial cold, often of great intensity, by the ra- 
pid solution of certain saline bodies in water. Upon this principle the 
action of freezing mixtures depends, some of which may frequently be 
conveniently and oeconomically applied to the purpose of cooling wine 
or water in hot climates, or where ice cannot be procured. The fol- 
lowing Table shews the results of some of Mr. Walker’s experiments 
on this subject. 
Latent calo 
rie 
Mixtures. 
Thermometer sinks. 
Parts. 
Muriate of ammonia 5 
Nitre 5 
Water 16 
From 50° to 10? 
Nitrate of ammonia 1 
Water 1 
Froin 50° to 4° 
Sulphate of soda 5 
Diluted sulphuric acid 4 
From 50° to 3° 
Snow 1 
Commmon salt 1 
From 32° to 0° 
Muriate of lime 3 
Snow 2 
Fram 32° to—50° 
Snow 2 
Diluted sulphuric acid 1 
Diluted nitric acid 1 
From—10° to—56° 
Snow or pounded ice 12 
Common salt 5 
Nitrate of ammonia 5 
From—18° to—25° 
Muriate of lime 3 
Snow 1 
From—40® to—73* 
Diluted sulphuric acid 10 
Snow 8 
From—68° to—919 
Table of fri- 
gorific mix- 
tures. HEAT. 
In order to produce these effects, the salts employed must be fresh 
crystallized, and newly reduced to a very fine powder. The vessels 
in which the freezing mixture is made should be very thin, and just 
large enough to hold it, and the materials should be mixed together as 
quickly as possible. 
In order to produce great cold, they ought to be first reduced to the 
temperature marked in the table, by placing them in some of the other 
freezing mixtures ; and then they are to be mixed together in a simi- 
lar freezing mixture.—Phil. Trans., 1795. 
82. When fluids are converted into solids, their latent heat becomes 
sensible ; thus when a solution of Glauber’s salt is made suddenly to 
crystallize (16), its temperature is considerably augmented ; and when 
water is poured upon quicklime, a great degree of heat is produced by 
the solidification which it suffers in consequence of chemical combina- 
tion ; congelation, therefore, is to surrounding bodies a heating process 
and liquefaction a cooling process. 
83. When liquids are heated, they acquire the gaseous form, and be- 
come invisible elastic fluids, possessed of the mechanical properties of 
common air. They retain this form or state as long as their tempera- 
ture remains sufficiently high, but re-assume the liquid form when 
cooled again. Different fluids pass into the aeriform state at different 
temperatures, or their boiling points are different; these are also re- 
gulated by the density of the atmosphere. If we diminish atmospheric 
pressure, we lower the boiling point. When the barometer is at 28 
inches, water will boil at a lower temperature than when it is at 31 
inches. Water under mean atmospheric pressure boils at 212Q. Al 
the top of Mont Blanc, Saussure found that it boiled at 187v, so that 
the heights of mountains, and even of buildings, may be calculated by 
reference to the temperature at which water boils upon their summits. 
The Reverend Mr. Wollaston has described to the Royal Society the 
method of constructing a thermometer of extreme delicacy, applica- 
ble to these purposes,—Phil. Trans., 1817. In the vacuum of an air- 
pump, fluids boil at temperatures considerably below their ordinarj 
boiling points. 
84. The following apparently paradox- 
ical experiment also illustrates the influ- 
ence of diminished pressure in facilitat- 
ing ebullition. Insert a stopcock secure- 
ly into the neck of a Florence flask, 
containing a little water, and heat it over 
a lamp till the water boils, and the steam 
freely escapes by the open stopcock; then 
suddenly remove the lamp and close the 
cock. The water will soon cease to boil ; 
but if plunged into a vessel of cold water 
ebullition instantly recommences, but 
ceases if the flask be held near the fire : 
the vacuum in this case being produced 
by the condensation of the steam. 
Circumstances 
to be attended 
to. 
Latent calorie 
made sensible. 
Altitudes de- 
termined by 
the changes is 
the boiling 
points of wa- 
ter. 
Example »{ 
diminished 
pressure facil- 
itating ebulli- 
tion, 30 
HEAT. 
85. Under increased pressure on the con- 
trary, fluids require a higher temperature 
s- to produce their ebullition, as may be shown 
by the following experiments, a is a strong 
brass globe, composed of two hemispheres 
screwed together with flanches ; a portion of 
quicksilver is introduced into it, and it is then 
about half tilled with water, b is a barome- 
ter-tube passing through a steam-tight collar, 
and dipping into the quicksilver at the bot- 
tom of the globe, c is a thermometer gra- 
duated to about 400°, and also passing 
through an air-tight collar, d is a stopcock, 
and e a large spirit lamp. The whole is 
supported upon the brass frame and stand/. 
Upon applying heat to this vessel, the stop- 
cock being closed as soon as the water boils, 
it will be found that the temperature of the 
water and its vapour increases with the 
pressure, which is measured by the ascent 
qfthe mercury in the barometer-tube. The 
thermometer under atmospheric pressure 
being at 212°, will be elevated to 217° un- 
der a pressure of five inches of mercury, 
and to 242° under a pressure of 30 inches, 
or thereabouts ; each inch of mercury pro- 
ducing by its pressure a rise of about I*5 in 
the thermometer. The barometer-tube al- 
so serves the purpose of a safety-valve, the 
strength of the brass globe being such as to 
resist a greater pressure than that of one at- 
mosphere. 
86. The conversion of a liquid into vapour is always attended with 
great loss of thermometric heat; and as liquids may be regarded as 
compounds of solids and heat, so vapours may be considered as con- 
sisting of a similar combination of heat with liquids ; in other words, 
a great quantity of heat becomes latent during the formation ot vapour. 
This is easily illustrated by immersing a thermometer into an open 
vessel of water placed over a lamp. The quicksilver rises to 212y, 
the water then boils, and although the source of heat remains, neither 
the water nor the steam acquire a higher temperature than 212° ; the 
heat then becomes latent, and is consumed in the formation of steam. 
87. To ascertain the absolute loss of thermometric heat in this case, 
Kxarnple of 
the contrary 
effect of pres- 
sure. 
Seasible or 
free caloric 
made latent. HEAT 
31 
Dr. Black instituted the following experiments : he noted the time re- 
quired to raise a certain quantity of water to its boiling point; he then 
kept up the same heat till the whole was evaporated, and marked the 
time consumed by the process ; it was thus computed to what height the 
temperature would have risen, supposing the rise to have gone on 
above 212°, in the same ratio as below it; and as the temperature of 
the steam was the same as that of the water, it was fairly inferred that 
all the heat above 212° was essential to the constitution of aqueous va- 
pour. Dr. Black estimated this quantity at about 810° ; that is, the 
same quantity of heat which is required for the total evaporation of 
boiling water at 212° would be sufficient to raise the water 810° above 
its boiling point, or to 1022° had it continued in the liquid state. There 
are other means of ascertaining the latent heat of steam, which lead us 
to place it between 900° and 1000°. 
88. The following table of the latent heat of steam and some other 
vapours is extracted from a paper in the Philosophical Transactions for 
1818, by Dr. Ure. 
Dr. Black’s 
estimate of la- 
tent caloric is 
aqueous va- 
pours. 
Vapour of Water at 212° . . . . 
967°.00 
Alcohol 
442 
.00 
Ether 
302 
.38 
Petroleum 
177 
.87 
• Oil of Turpentine . . 
177 
.87 
531 
99 
Liquid Ammonia . . . 
837 
.28 
Vinegar . . . 
875 
.00 
89. When steam is again condensed, or when vapours re-assume the 
liquid state, their latent heat becomes sensible ; and in this way it is 
obvious that a small quantity of steam will, during its condensation com- 
municate heat sufficient to boil a large quantity of water. 
The small boiler, represented in the annexed cut taken from Dr. 
Henry’s Elements of Chemistry, may be conveniently employed in ex- 
periments on the latent heat of steam. 
Table of the 
latent caloric 
of several 
fluids by 
Dr. Ure. 
Dr. Henry’s 
instrument for 
determining 
the heating 
power of con- 
densed stea'ni 32 
HEAT. 
For this purpose the tube e must be screwed on the stop-cock b, and 
immersed into the glass of water/. The cock c being closed, the 
steam arising from the boilingjjwater a will pass into the cold water/, 
the temperature of which will be much augmented by its condensation. 
Ascertain the increase of temperature and weight, and the result will 
show how much a given weight of water has had its temperature raised 
by a certain weight of condensed steam. To another quantity of water, 
of the same weight and temperature as that in the jar at the outset of the 
experiment, add a quantity of water at 212°, equal in weight to the con- 
densed steam ; it will be found, on comparing the resulting tempera- 
tures, that a given weight of steam has produced, by its condensation, a 
much greater elevation of temperature than the same quantity of boil- 
ing water.—Henry, Vol. i. p. 106, 7th edit. 
90. In breweries and other manufactories, where large quantities of 
warm and boiling water are consumed, it is frequently heated by thus 
conveying steam into it, or by suffering steam-pipes to traverse the ves- 
sels or by employing double vessels, a plan adopted with particular ad- 
vantage in the laboratories at Apothecaries Hall. This method of 
warming water has also been very advantageously applied to heating 
baths. Where a higher temperature than 212° is required it is neces- 
sary to employ steam under adequate pressure, and a very ingenious 
means of producing high pressure steam for this purpose has been 
contrived by Messrs. J. and P. Taylor, and applied by them, upon a 
very large scale, at Whitbread and Co.’s brewhouse. 
The heat given off by steam during its condensation, is also often ad- 
vantageously applied to warming buildings, and is at once safe, salubri- 
ous, and economical. 
91. The cold produced by evaporation is, under certain circumstan- 
ces, very great. Spirit of wine, and ether, which readily evaporate, 
produce considerable cold during that process. Upon this principle 
wine-coolers, and similar porous vessels, refrigerate the fluids they 
contain ; and thus, by accelerating the evaporation of water, by expos- 
ing it under an exhausted receiver, containing bodies that quickly ab- 
sorb its vapour, Professor Leslie has contrived to effect its congelation ; 
the heat required for the conversion of one portion of the water into 
vapour being taken from the other portion, which is thus reduced to ice. 
—See Supplement to Encycloptedia Brit., Art. Cold. 
92. The instrument invented by Dr. Wollaston, and called by him 
the Cryophorus, acts upon a similar principle. It consists of a glass 
tube with a bulb at each extremity, of the shape annexed. 
’Khis property 
taken advan- 
tage of in 
seme arts. 
Reduction of 
temperature 
fey evapora- 
tion. 
Sryophovus of 
Wollaston. 
One of the bulbs is about half filled with with water, and a good va- 
cuum is produced in the other by boiling the water and sealing the tube 
whilst full of steam. On immersing the empty bulb in a freezing-mix- 
ture, the water soon congeals in the other, although the intervening tube 
he two or three feet long. The vapour in the empty bulb is condensed HEAT. 
33 
by the cold, and a fresh quantity of vapour arises successively from the 
water in the other, by which so much heat is carried off as to cause it to 
congeal.—Phil. Trans. 1813. 
93. In many natural operations the conversion of water into vapour, 
and the condensation of vapour in the form of dew and rain, is a process 
of the utmost importance, and tends considerably to the equalization of 
temperature over the globe. 
94. Nothing is known of the nature or cause of heat. It has been 
by some considered as a peculiar fluid, to which the term Caloric has\ 
been applied ; and many phenomena are in favour of the existence of 
such a fluid. By others, the phenomena above described have been 
referred to a vibratory motion of the particles of matter, varying in ve-. 
locity with the perceived intensity of the heat. In fluids and gases the1 
particles are conceived to have a motion round their own axes. Tem- 
perature., therefore, would increase with the velocity of the vibrations ; 
and increase of capacity would be produced by the motion being per- 
formed in greater space. The loss of temperature, during the change 
of solids into liquids and gases, would depend upon loss of vibratory 
motion, in consequence of the acquired rotatory motion. 
Upon the other hypothesis, temperature is referred to the quantity of 
caloric present; and the loss of temperature, which happens when bo- 
dies change their state, depends upon the chemical combination of the 
caloric with the solid in the case of liquefaction, and with the liquid in 
the case of conversion into the aeriform state. 
Caloric a 
fluid. 
A vibratory 
motion. 
Section IV. Electricity. 
95. If a piece of sealing-wax and of dry warm flannel be rubbed a- 
gainst each other, they both become capable of attracting and repelling 
light bodies. A dry and warm sheet of writing-paper, rubbed with In- 
dia rubber, or a tube of glass rubbed upon silk, exhibit the same phe- 
nomena. In these cases the bodies are said to be electrically excited ; 
and when in a dark room, they always appear luminous. 
96. If two pith-balls be electrified by touching them with the seal- 
ing-wax or with the flannel, they repel each other ; but if one pith-ball 
be electrified by the wax, and the other by the flannel, they attract 
each other. The same applies to the glass and silk : it shows a diffe- 
rence in the electricities ofthe different bodies, and the experiment leads 
to the conclusion, that bodies similarly electrified repel each other, but 
that when dissimilarly electrified they attract each other. 
The term electrical repulsion is here used merely to denote the ap- 
pearance of the phenomenon, the separation being probably referable 
to the new attractive power which they acquire, when electrified, for 
the air and other surrounding bodies. 
If one ball be electrified by sealing-wax rubbed by flannel, and an- 
other by silk rubbed with glass, those balls will repel each other; 
which proves that the electricity of the silk is the same as that of the 
sealing-wax. But if one ball be electrified by the sealing-wax and the 
Electrical ex- 
citement. 
Repulsion and 
attraction. 
Repulsion. ELECTRICITY. 
other by the glass, they then attract each other, showing that they are 
oppositely electrified. 
These experiments are most conveniently performed with a large 
downy feather suspended by a silken thread. If an excited glass tube 
be brought near it, it will receive and retain its electricity ; it will be 
first attracted, and then repelled, and upon re-exciting the tube, and 
again approaching it, it will not again be attracted, but retain its state 
of repulsion : but upon approaching it with excited sealing-wax, it 
will instantly be attracted, and remain in contact with the wax till it 
has acquired its electricity, when it will be repelled, and in that state 
of repulsion it will be attracted by the glass. In these experiments 
care must be taken that the feather remains freely suspended in the air, 
and touches nothing capable of carrying off its electricity. 
97. The terms vitreous and resinous electricity were applied to these 
two phenomena.; but Franklin, observing that the same electricity 
was not inherent in the same body, but that glass sometimes exhibited 
the same phaenomena as wax, and vice versd, adopted another term, and, 
instead of regarding the phasnomena a3 dependent upon two electric 
fluids, referred them to the presence of one fluid, in excess in some 
cases, and in deficiency in others. To represent these states he used 
the terms plus and minus, positive and negative. When glass is rubbed 
with silk, a portion of electricity leaves the silk and enters the glass ; it 
becomes positive, therefore, and the silk negative; but when sealing- 
wax is rubbed with flannel, the wax loses and the flannel gains ; the for- 
mer, therefore, is negative, and the latter positive. All bodies in na- 
ture are thus regarded as containing the electric fluid, and when its 
equilibrium is disturbed, they exhibit the phaenomena just described. 
98. The substances enumerated in the following table become posi- 
tively electrified when rubbed with those which follow them in the list, 
but with those which precede them they become negatively electrical. 
—Biot, Traite de Physique, tom. ii., p. 220. 
Franklin's 
theory. 
Cat’s skin 
Polished glass 
Woollen cloth 
Feathers 
Paper 
Silk 
Gum lac 
Rough glass. 
99. Very delicate pith-balls, or strips of gold leaf, are usually em- 
ployed in ascertaining the presence of electricity ; and, 
by the way in which their divergence is affected by 
glass or sealing wax, the kind or state of electricity is 
judged of. When properly suspended or mounted for 
delicate experiments, they form an electrometer or elec- 
troscope. For this purpose the slips of gold leaf are 
suspended by a brass cap and wire in a glass cylinder; 
they hang in contact when unelectrified ; but when 
electrified they diverge, as in the marginal wood- 
rnf 
Electrometer. electricity. 
35 
When this instrument, as usually constructed, becomes in a small 
degree damp, its delicacy is much diminished, and it is rendered near- 
ly useless. The following improvement in its construction by the 
late Mr. Singer renders it a much more sensible and useful instrument. 
It is constructed as usual, with a glass cylinder, surmounted by a brass 
cap ; but the insulation is made to depend upon a glass tube, about 
four inches long, and one-fourth of an inch internal diameter, covered 
both on the inside and outside with sealing-wax, anc 
having a brass wire of a sixteenth or twelfth of an incli 
thick and live inches long, passing through its axis, 
so as to be perfectly free from contact with any pari 
of the tube, in the middle of which it is fixed by s 
plug of silk which keeps it concentric with the in- 
ternal diameter of the tube. a, is a brass cap 
screwed upon the upper part of this wire ; it serves 
to limit the atmosphere from free contact with the 
outside of the tube, and also defends its inside front 
dust; to the lower part of the wire the gold leaves 
are attached, and the whole mounted as usual, and as represented 
above. 
100. The kind of electricity by which the gold leaves are diverged 
may be judged of by approaching the cap of the instrument with a 
-stick of excited sealing-wrax ; if it be negative the divergence will in- 
crease ; if positive, the leaves will collapse, upon the principle of the 
mutual annihilation of the opposite electricities, or that bodies simi- 
larly electrified repel each other, but that when dissimilarly electrified 
they become mutually attractive. (96.) 
101. To ascertain the actual repulsive and at- 
tractive powers appertaining to weakly-electrifi- 
ed bodies, M. Coulomb has ingeniously availed 
himself of the principle of torsion, and has thus 
constructed his electrical balance. It consists of 
a fine metallic wire, a, one end of which is at- 
tached to the screw b, and to the other is suspend- 
ed the horizontal needle c, composed of gum-lac 
or other nonconductor, and armed at one extre- 
mity with a gilt pith-ball, counterpoised at the 
other end by an index. The conductor d, is a 
small wire with a ball at each end passing through 
the glass receiver in which the needle is sus- 
pended, and having its lower ball opposed to that 
of the needle. By the screw b, the two balls are 
brought into contact,' and the index then points to 
#, on the divided scale of degrees. On commu- 
nicating a very feeble electrical power to the conductor, it transfers it 
to the moveable pith-ball, and repels it a certain number of degrees, 
proportional to the intensity of the acquired electricity, and measured 
by the power of torsion which it exerts upon the fine wire. By expe- 
riments made with this electrometer, it would appear that the electri- 
cal powers follow the law of gravitation, in being in the inverse ratio of 
the squares of the distances of the acting bodies. In the most deli- 
cate construction of the instrument a single thread is used 
instead of the wire. 
Singer’s im- 
provement. 
Method of de- 
termining the 
kind of elec- 
tricity. 
Coulomb’s e- 
lectrical ba 
lanes. 
Electrical 
powers are in- 
versely as the 
squaresoftheir 
distances i. e. 
similar to the 
powers of grv* 
▼jUtioa. 36 
ELECTRICITY. 
Conductors & 
nonconductors. 
102. Some bodies suffer electricity to pass through their substance, 
and are called conductors. Others only receive it upon the spot 
touched, and are called nonconductors. The former do not, in general 
become electric by friction, and are called nonelectrics: the latter, on 
the contrary, are electrics, or acquire electricity by friction. They 
are also called insulators. The metals are all conductors ; dry air. 
glass, sulphur, and resins, are nonconductors. Water, damp wood, 
spirit of wine, damp air, and some oils, are imperfect conductors. 
103. Rarefied air admits of the passage of electricity ; so does the 
Torricellian vacuum: hence if an electrified body be placed under 
the receiver of the air-pump, it loses its electricity during exhaustion. 
So that the air, independent of its nonconducting power, appears to 
influence the retentive properties of bodies in respect to electricity, 
by its pressure. 
104. There appears to be no constant relation between the state of 
bodies and their conducting powers : among solids, metals are conduc- 
tors, hut gums and resins are nonconductors ; among liquids, strong al- 
caline, acid, and saline solutions, are good conductors ; pure water is 
an imperfect conductor, and oils are nonconductors ; solid wax is al- 
most a nonconductor, but when melted, a good one. Conducting pow- 
ers belong to bodies in the most opposite states ; thus the flame of 
alcohol, and ice, are equally good conductors. (Biot, Traite de Phy- 
sique, tom. ii., p. 213.) Glass is a nonconductor when cold, hut con- 
ducts when red-hot; the diamond is a nonconductor, but pure and well- 
burned charcoal is among the best conductors. 
105. There are many mineral substances which show signs of elec- 
tricity when heated, as the tourmalin, topaz, diamond, boracite, &c. ; 
and in these bodies the different surfaces exhibit different electrical 
states. 
106. Whenever one part of a body, or system of bodies, is positive, 
another part is invariably negative ; and these opposite electrical states 
are always such as exactly to neutralize each other. Thus, in the 
common electrical machine, one conductor receives the electricity of 
of the glass cylinder, and the other that of the silk rubber, and the 
former conductor is positive and the latter negative ; but if they be 
connected, all electrical pha3nomena cease. 
107. The best electrical machine for experimental purposes is re- 
presented in the annexed sketch. 
Electricity 
passes through 
rarefied air or 
a racuum. 
No constant 
relation be- 
tween the 
state of bodies 
and their con- 
ducting pow- 
ers. 
Some sub- 
stances be- 
come electric 
by being heat- 
ed. 
Opposite elec- 
tricities at op- 
posite sides of 
a body. ELECTRICITY- 
Electrical 
machine. 
It consists of a glass cylinder a about 10 or 12 inches in diameter, and 
15 to 20 inches in length, turning between two upright pillars of glass, 
b b, fixed to a stout mahogany base. Two smooth metal conductors, 
equal in length to the cylinder, and about one-third of its diameter, c 
c, are placed parallel to it upon two glass pillars, d d, which are ce- 
mented into two sliding pieces of wood e, by which their distance from 
the cylinder may be adjusted. One of the conductors has a cushion, 
f, attached to it by a bent metallic spring, nearly as long as the cylinder, 
and about one inch or an inch and a half wide, to the upper part of 
which is sewed a flap of oil-silk, g, which should reach from the cush- 
ion over the upper surface of the glass cylinder, to within about an 
inch of a row of points attached to the side of the opposite conductor. 
The conductor to which the cushion is attached is called the negative 
conductor ; the other collects the electricity of the glass, and is called 
the positive conductor, h, is an adjusting screw to regulate the. pres- 
sure of the cushion upon the cylinder. The motion of the cylinder is 
in the direction of the silk flap, and may be communicated by a handle 
attached at i, or by the multiplying wheel k. To put this electrical 
machine into good action, every part should be made perfectly clean 
and dry. The cushion is then anointed with amalgam, and applied by 
a gentle pressure to the cylinder. If positive electricity is required, 
ibmay be received from the conductor bearing the points, that suppor- 
ting the cushion being uninsulated by a wire passing from it to the 
stand ;—if, on the contrary, negative electricity is required, it may be 
obtained from the insulated cushion cylinder, the other being uninsu- 
lated. 
Description. 
Method of us- 
ing it. ELECTRICITY. 
A malgam for 
inciting elec- 
tric ity. 
108. The best amalgam is composed of one part of tin and two of zinc 
melted together, and mixed, while fluid, with six parts of hot mercury in 
an iron mortar. This mixture is triturated till it becomes a fine pow- 
der, which is then formed into a tenacious paste with hogs’ lard. 
109. Another form of the electrical machine consists of a circular 
glass plate a, mounted upon an axis and rubbed by two pairs of cush- 
Another form 
of electrical 
machine 
PescriptioB. 
ions, as shewn at e b. The brass conductor c has its points opposed 
to the plate, and is insulated by the glass stem d.—e e are double 
pieces of oil-silk passing from the cushions to near the points. The 
whole is supported by a stout mahogany frame, and motion is given to 
the plate by the winch f. 
. These electrical machines have considerable power ; they are easi- 
ly cleaned and excited, and are more portable than the cylinders ; but 
as they cannot be conveniently insulated, the negative electrical pow- 
er cannot he well exhibited, so that for the purposes of experimental 
reseax'ch the former machines are preferable. 
110. When the electrical machine is in good order, and the atmos- 
phere dry, it produces a crackling noise when the plate or cylinder is 
turned, and flashes and sparks of light are seen upon various parts of the 
glass passing from the cushion to the conductor: if the knuckle be 
held near the conductor, sparks pass to it through some inches of air, 
with a peculiar noise, and excite slightly painful sensation in the part 
upon which they are received. It is conjectured that the cause of the 
light thus perceived, is the sudden compression of the air or medium 
through which the electricity passes, and it is always probably attend- 
ed by a proportionate elevation of temperature, as is shown by the pow- 
er ot the spark to inflame spirit of wine, fulminating silver, and other 
easily inflammable compounds. 
111. The appearance of the electric light is modified by the densi- 
ty of the medium through which it passes. In dense air it is bright 
and white ; in rarefied air it is of a reddish tinge and faint and divided; 
Advantages & 
vice versa. 
yhmnomena 
ebserved in 
using these 
machines. 
.Effect of a 
change, in tile 
density of a 
medium upon 
electric light. ELECTRICITY. 
and in the more perfect vacuum of a good air-pump, it is of a purplish 
hue, and scarcely visible except in a very dark room. 
112. If an insulated conductor be electrified, and an uninsulated con- 
ductor be opposed to it, there being between the two a thin stratum of 
air, glass, or other nonconductor, the uninsulated conductor, under 
such circumstances, acquires an opposite electrical state to that of the 
originally electrified insulated conductor. In this case, the uninsulat-j 
ed body is said to be electrified by induction and the induced electri-1 
city remains evident, until an explosion, spark, or discharge happens, 
when the opposite electricities annihilate each other. Induced elec- 
tricity may thus be exhibited through along series of insulated conduc- 
tors, provided the last of the series be communicated with the earth. 
Thus, in the following diagram, a, may represent the positive con- 
ductor of the electrical machine ; b,c, and d, three insulated conduc- 
tors, placed at a little distance from each other, d having a chain touch- 
ing the ground ; then the balls 1, being positive, will attract the balls1 
2, which are rendered negative by induction. Under these circum- 
stances, each of the conductors becomes polar, and the balls 3 are 
positive, while 4 are negative, 5 positive, 6 negative, 4*c. : the central 
•points of the conductors, b c d, are neutral. When these opposite 
electrical states have arrived at a certain intensity, sparks pass between 
the different conductors, and the electrical phenomena cease. 
Electrir.it}' ¥y 
induction. *" 
Hlustrau«ii. 
i 13. The extent of such a polar arrangement may 
be greatly increased by pasting small spangles of tin- 
foil, upon a clean plate of glass, within a small dis- 
tance of each other, each of which will then repre- 
sent an insulated conductor ; and the first spangle be- 
ing held near the excited conductor of the machine, 
and the last in the hand, a series of brilliant sparks 
will pass between each, indicating the annihilation of 
the opposite electrical states. The spiral luminous 
tube, a, luminous words, flowers, &c., are arrange- 
ments of this kind. 
Spiral lumi- 
nous tube. 
114. Upon the principle of induction it is that the accumulation of 
electricity in the Leyden phial is effected. It consists 
of a thin glass jar, coated internally and externally, 
with tinfoil to within a short distance of its mouth. 
When the inner surface is rendered positive by union 
with the conductor of the electrical machine, the ex- 
terior, being connected with the ground, becomes nega- 
tive by induction. When the inner and outer surfaces 
are united by a conductor, all electrical accumulation is 
annihilated by a powerful spark, and the two opposite 
states are found to have been precisely equivalent. 
Leyden phht ELECTRICITY. 
If the communication between the opposite surfaces of the Leyden 
phial be made by the hands, a painful jarring sensation is felt at the joints 
of the fingers, the elbows shoulders, and chest, commonly called the 
electrical shock. Metallic wires, with balls at their ends, bent or joint- 
ed and fixed to a glass handle, are generally used to transfer the elec- 
tric charge, and these instruments are called dischargers. 
115. In all cases of electrical accumulation, the surfaces intended to 
retain it must be free from asperities, and points : a pointed wire held 
near the prime conductor instantly gains an opposite state, and rapidly 
discharges it; if it be affixed to the conductor, a similar effect is ob- 
served ; and upon holding the hand near the point, a peculiar coldness 
is perceived, which has been called the electrical aura, and which de- 
pends upon the rapid recession of the electrified air. If the Leyden 
jar be discharged by a pointed wire, the electricities quietly annihilate 
each other, and no explosion can be produced. 
116. To ascertain the relative charge which 
the jar has received, we employ the quadrant elec- 
trometer, contrived by Henly. It consists of a 
rounded stem of metal, a to the side of which is 
attached an ivory semi-circle, b ; to the centre is 
affixed a pin, upon which a very thin piece of cane 
or ivory, about 4 inches long, with a pith ball at 
its lower extremity, turns freely, traversing the 
semicircle as an index. The lower half of the se- 
mi-circle is divided into 90°. When not electri- 
fied, its index hangs parallel to the stem at 0°, but 
when electrified, the ball recedes and carries the 
index over the graduated circle to a greater or less extent, in propor- 
tion to the intensity of the electricity. 
117. The annihilation of positive by negative electricity, and vice 
versd, may be well shown by the following experiment. Attach Hen- 
ly’s quadrant electrometer to the knob of a Leyden jar, and give it a 
certain charge from the positive conductor : then transfer the jar to 
the negative conductor, and whilst receiving a negative charge, the 
electrometer will fall, indicating the loss of all electrical accumulation ; 
it then will again rise as the jar becomes negatively charged, and may 
again be discharged by transferring it to the positive conductor. 
118. If one Leyden jar be insulated with its internal surface con- 
nected with the positive conductor, another jar may be charged from 
its exterior coating ; and if this second jar be insulated, a third maybe 
charged from its exterior coating, and so on for any number of jars, 
provided always that the exterior coating of the last jar be connected 
with the ground. In this case, a polar arrangement, similar to that of 
the conductors just described, (112) will have been formed, glass be- 
ing the medium of induction instead of air. 
Electrical 
wind or cold- 
ness. 
Henly’s elec- 
trometer. 
Experiment to 
shew the anni- 
hilation of op- 
posite electri- 
cities. 
Connection of, 
Leyden jars. ' Let c p be the positive conductor of the electrical machine, and a 
c three insulated Leyden phials, the outer coating of c being connected 
with the ground ; it is then obvious, that there will he the same polar 
state as in the conductors just noticed ; that the insides of a, b, and c, 
will be positive, and the outsides negative ; and that, consequently, on 
removing the jars from each other, they will all be similarly charged, 
and that if the three inner surfaces p p p and the outer surfaces n n n 
be united, the whole may be discharged as one jar. 
119. Upon this principle a jar may be charged by the transfer of its 
inherent electricity from one surface to the other, by insulating it and 
connecting its interior coating with the positive conductor, and its exte- 
rior with the negative ;—thus the electricity received by the lormer is 
withdrawn from the latter, and the jar becomes charged. This expe- 
riment well illustrates the non conducting power of glass. 
120. The use of the metallic coatings of the Leyden phial is equal- 
ly to distribute the electricities over the opposite surfaces, for if the 
coatings be made moveable the jar remains charged when they are re- 
moved. In discharging the jar, too, the annihilation is rendered si- 
multaneous by the conducting coating suffering the transfer of the op- 
posite electricities from every part of the glass surfaces at the same 
instant. 
121. There are some other electrical instruments (the operation o 
which is referable to the phenomena of induction, such as the electro- 
phorus, and the condenser. 
The electrophorus consists of two metallic plates, a a, with an in- 
tervening plate of resinous matter, b, for which equal parts of shell- 
lac, resin, and Venice turpentine, are generally used, the mixture be- 
ing carefully melted in a pipkin, and poured, whilst liquid, into a wood- 
en or metal hoop, of a proper size, placed upon a polished surface o 
glass or marble, from which it easily separates when cold ; it shouh 
be about half an inch thick, and the smooth surface being uppermos 
the lower side should be covered w ith 
tin foil, or attached to any other metal- 
lic plate ; a polished brass plate, w ith 
a glass handle c attached to it, is then 
placed upon the upper surface of the 
resinous plate, and of rather smaller 
diameter. The resin is then to be ex- 
cited with a piece of dry fur, and the 
instrument will be found to exhibit the 
following phenomena : 
Upon raising the brass plate by its insulating handle, it will be found 
very feebly electrical; replace it, touch it with the finger and again 
lift it off by its handle, and it will give a spark of positive electricity. 
This process may very often be repeated without fresh excitation, 
which circumstance, as well as the nature of the electrical charge, 
shows that the electricity of the moveable brass plate is not directly 
derived from the resin, but that it depends upon induction: this is 
more obvious by considering the upper plate, not as in contact with 
but merely very near the resinous disc, w'hich from the minute irre- 
gularities upon its surface, is really the case ; the negative electricity, 
therefore, of the excited resinous plate is communicated from a few 
ELECTRICITY. 
41 
Use of the me1 
gallic coatings 
of the Leyden 
jar. 
Electrophorns 
Mode of usiftjj 
it. ELECTPICTTY. 
mints oi contact to the brass plate, upon its first application, and then 
he latter is precisely in the state of a conductor opposed to, but not 
:ouching, an electrified surface, and consequently in due condition to 
ie rendered electrical by induction, when occasionally uninsulated by 
die contact of the finger. 
With this instrument, one phenomenon of induction may be shown, 
which cannot be so well exhibited by any other ; namely, the increas- 
ed capacity for electricity of the conductor under the influence of in- 
duction. The brass plate, when placed upon the resin, may be re- 
garded as in a polar state; the lower surface next the resin being po- 
sitive, the upper surface being negative. Upon touching the upper 
surface with the finger, it instantly acquires electricity, loses its po- 
larity, and becomes positive, giving, upon removal, a positive spark to 
iny conductor. That the quantity of electricity received from the fin- 
der, or other source, is equivalent to that given out, is shown by the 
following experiment: Place the metallic upon the resinous plate, and 
ouch the former with the knob of a Leyden phial; then touch the cap 
if an electrometer with the knob of the phial, and it will give a certain ne- 
gative divergence to the leaves ; raise the plate and present the knob of 
he jar to it, a spark will pass ; and upon applying the jar a second time 
;o the electrometer, the leaves will entirely collapse, showing the ex- 
lct annihilation of the former negative, by the latter positive charge. 
When the electrophorus is placed upon an insulating stand, its low- 
jr plate is always found in an opposite electrical state to the upper one, 
io that in this respect it resembles the coatings of a Leyden jar. 
The electrophorus may often be used for the same purposes as the 
electrical machine, and in the laboratory it furnishes a very conve- 
nient substitute for that more expensive piece of apparatus. 
122. When an insulated surface is opposed to another which is not 
nsulated, so as to be affected by it by induction, the electricity commu- 
nicated to the former suffers a singular increase of tension or intensity 
an breaking the induction by removing the opposed uninsulated con- 
iuctor ; this property is strikingly exhibited in the following experi- 
nent:—Provide a brass plate, 3 or 4, inches in diameter, and dropup- 
m its lower surface three small spots of sealing-wax ; place it upon a 
similar plate, forming the cap of the gold leaf electrometer, from which 
t will be separated about a twentieth of an inch by the three small 
nsulating legs of wax. Connect the upper plate with the ground by 
touching it, and give a very feeble electrical charge to the electrometer, 
so as scarcely perceptibly to diverge its leaves ; then suddenly remove 
the upper plate, by which the induction will be broken, and the ten- 
don of the electricity suddenly increased, so as to cause a very consi- 
derable divergence of the leaves. 
The plates employed in this experi- 
ment have been called condensers. 
They are sometimes placed perpendi- 
cularly, and the uninsulated plate a is 
supported by a wire and joint, so as to 
be brought as close as possible to the 
insulated plate b, without touching ; 
the latter is in communication with the 
electrometer, and having received its 
charge, the moveable uninsulated plate 
is drawn back, as in c, and the intensity of the electricity displayed. 
A phenome- 
non of induc- 
tion, we.l 
shown by this 
instrument- 
The elcctro- 
phorus used as 
an electric ma- 
chine. 
Singular Phe- 
nomenon con- 
nected with 
induction. 
Condensers. ELECTRICITY. 
43 
sometimes the condenser is directly attach- 
ed to the electrometer, as shown in the an- 
nexed cut.—a, the insulated plate ; b, the mo- 
veable plate in communication with the 
ground. 
Various attempts have been made so to 
combine electrical condensers, as to multiply 
their effect, and render very slight electrical 
changes susceptible of measurement and ex- 
amination ; of this nature is the Electrical Mul- 
tiplier, contrived by Mr. Cavallo, (Complete 
Treatise on Electricity, Vol. iii. p. 99 ;) the 
Doublers of Mr. Bennet and Mr. Nicholson, 
{Phil. Trans, lxxvii. and lxxviii.) and Mr. Wilson’s Double Multiplier 
(Nicholson’s Journal, ix ;) but the complexity of these instruments 
as Mr. Singer has remarked, renders their results equivocal, and ofter 
lias a tendency to produce the electrical states, independent of the in- 
tended source, or to change that originally communicated. 
123. Electricians generally employ the term quantity to indicate the 
absolute quantity of electric power in any body, and the term intensi- 
ty to signify its power of passing through a certain stratum of air oi 
other ill-conducting medium. 
If we suppose a charged Leyden phial to furnish a spark, when dis- 
charged, of one inch in length, we should find that another unchargec 
Leyden phial, the inner and outer coating of which were communicat 
ed with those of the former, wrnuld upon the same quantity of electri 
city being thrown in, reduce the length of the spark to half an inch 
here, the quantity of electricity remaining the same, its intensity is di 
minished by one-half, by its distribution over the larger surface. 
124. It is obvious, that the extension of surface alluded to in the las 
paragraph, will be attended with a greater superficial exposure to the 
unelectrified air ; and hence it might be expected, that a similar dimi- 
nution of intensity would result from the vicinity of the electrifiec 
surface to the ground, or to any other body of sufficient magnitude ir 
its ordinary state. That this is the case, may be shown by diverging 
the leaves of the gold-leaf electrometer, and in that state approaching 
the instrument with an uninsulated plate, which, when within half ar 
inch of the electrometer plate, will cause the leaves to collapse ; bul 
on removing the uninsulated plate, they will again diverge, in conse- 
quence of the electricity regaining its former intensity. The same 
fact is shown by the condensing electrometer. 
125. The power of the Leyden jar is proportioned to its surface, but 
a very large jar is inconvenient and difficult to procure ; the same 
end is attained by arranging several jars, so that by a communication 
existing between all their interior coatings, their exterior being also 
united, they may be charged and discharged as one jar. Such a com- 
bination is called an electrical Battery, and is useful for exhibiting the 
effect of accumulated electricity. 
The discharge of the battery is attended by a considerable report, 
and if it be passed through small animals it instantly kills them ; if 
through fine metallic wires, they are ignited, melted, and burned ; and 
gunpowder, cotton sprinkled with powdered resin, and a variety of 
other combustibles, may be inflamed bv the same means. 
Different ar- 
rangement of 
the conden- 
sers. 
Quantity & in- 
tensity of elec- 
tric power. 
Illustration. 
Power of the 
Leyden jar iq 
proportion to 
its surface. 
Electrical 
Battery. 
Its discharge 
■attended with 
report can 
prove fatal tp 
.animal life. 
produces com- 
bustion, &e. ELECTRICITY. 
Other sources 
of electricity. 
126. There are many other sources of electricity than those just 
noticed. When glass is rubbed by mercury, it becomes electrified, 
and this is the cause of the luminous appearance observed w hen a baro- 
meter is agitated in a dark room, in which case flashes of light are seen 
to traverse the empty part of the tube. Even the friction of air upon 
glass is attended by electrical excitation : for Mr. Wilson found that 
by blowing upon a dry plate of glass with a pair of bellows, it acquir- 
ed positive electricity. Whenever bodies change their forms, their 
electrical states are also altered. Thus the conversion of water into 
vapour, and the congelation of melted resins and sulphur, are pro- 
cesses in which electricity is also rendered sensible. 
127. When an insulated plate of zinc is brought into contact with 
one of copper or silver, it is found, after removal, to be positively 
electrical, and the silver or copper is left in the opposite state. 
5 The most oxidizable metal is always positive, in relation to the least 
oxidizable metal, which is negative, and the more opposite the metals 
in these respects, the greater the electrical excitation ; and if the 
metals be placed in the following order, each will become positive by 
the contact of that which precedes it, and negative by the contact 
of that which follows it; and the greatest effect will result from the 
contact of the most distant metals. 
Of two metals 
properly con- 
nected the 
most oxidiza- 
ble one is al- 
ways positive. 
Platinum. 
Gold. 
Silver. 
Mercury. 
Copper. 
Iron. 
Tin. 
Lead. 
Zinc. 
Metallic ar- 
rangement for 
electric exci- 
tation. 
Electricity 
conducted by 
nerves. 
If the nerve of a recently killed frog be attached to a silver probe, 
and a piece of zinc be brought into the contact of the muscular parts of 
the animal, violent convulsions are produced every time the metals 
thus connected are made to touch each other ; exactly the same effect 
is produced by an electric spark, or the discharge of a very small Ley 
den phial. 
If a piece of zinc be placed upon the tongue, and a piece of silver 
under it, a peculiar sensation will be perceived every time the two 
metals are made to touch. 
128. In these cases the chemical properties of the metals are ob- 
served to be affected. If a silver and a zinc wire be put into a wine glass 
full of dilute sulphuric acid, the zinc wire only will evolve gas ; but up- 
on bringing the two wires in contact with each other, the silver will 
also copiously produce air bubbles. 
129. If a number of alternations be made of copper or silver leaf, zinc 
leaf, and thin paper, the electricity excited by the contact of the metals 
will be rendered evident to the common electrometer.—a represents a 
glass tube, in which are regularly arranged a number of alternating 
plates of silver, zinc, and thin paper, forming de Luc’s electrical column. 
The metallic cap b is in contact with the silver plate, and c with the 
zinc plate, at the respective extremities of the pile. Upon examining 
Chemical ac- 
tion accompa- 
nying that of 
electricity. 
Electric co- 
il umn. ELECTRICITY. 
the electrometers, it will be found that b is negatively diverged, and c 
positively. 
De Luc’s ca- 
130. If the same arrangement be made with the 
paper moistened with brine, or a weak acid, it will be 
found on bringing a wire communicating with the last 
copper plate into contact with the first zinc plate, that 
a spark is perceptible, and also a slight shock, provi- 
ded the number of alternations be sufficiently nume- 
rous. This is the Voltaic apparatus. 
131. Several modes of constructing this apparatus 
have been adopted, with a view to render it more 
convenient or active. Sometimes double plates of 
copper and zinc soldered together, are cemented in- 
to wooden troughs in regular order, the intervening 
cells being filled with water, or saline or acid solu- 
tions. 
Volta's. 
Another mode 
of constructing 
the apparatus. 
132. Another form consists in arranging a row of glasses, containing 
dilute sulphuric acid, in each of which is placed a wire or plate of silver 
or copper, and one of zinc, not touching each other, hut so connected 
by metallic wires, that the zinc of the first cup may communicate with 
the copper of the second; the zinc of the second with the copper of 
the third, and so on throughout the series, as represented in the an - 
nexed cuts. 
Coronne <3e 
lasse an other 
variety of 
form. 
Fig. 1. ELECTRICITY. 
Fig. 2. 
By applying the moistened fingers to the extreme wires p and n, a 
shock will be felt; and on making a communication between them by a 
wire, it will be found that the copper plates in Fig. 1, and the silver 
wires in Fig. 2, instantly acquire the power of decomposing the dilute 
sulphuric acid, and that the chemical action of the zinc is much augment- 
ed. One advantage of this arrangement over the former (131) is, that 
both surfaces of the metal are exposed; whereas in the other, by sol- 
dering the plates together, its action is diminished. 
133. In the following sketch, the trough a is made of earthenware, 
with partitions of the same material, and the metallic plates are attach- 
ed to a bar of wood, arranged as in Fig. 1, so that they can be immersed 
The most ap- 
proved con- 
struction. 
and removed at one operation. The troughs are filled with dilute a- 
cid, and by uniting them in regular order, the apparatus may he en- 
larged to any extent. This is, on the whole, the best form of the 
Voltaic instrument hitherto devised, and it is thus that the great appa- 
ratus of the Royal Institution is constructed. 
134. When from 500 to 1000 double plates are thus arranged and ren- 
dered active by immersion into a liquid consisting of about sixty parts 
of water with one of nitric and one of sulphuric acid, very brilliant 
effects are produced when the opposite poles are properly united by 
conductors. Thus, if apiece of charcoal united with the negative wire 
be made to touch another piece united with the positive wire, a bright 
spark and intense ignition ensue, and by slowly withdrawing the points 
from each other a constant current of electricity takes place through 
the heated air, producing a magnificent arc of intense light, in the form 
here represented. ELECTRICITY. 
47 
Galvaniccom- 
bustion of 
charcoal. 
135. When the metals and other inflammable bodies are placed in 
this arc of fire they burn with great brilliancy, and those which are 
most difficult of fusion give evidence of the intensity of the heat by 
instantly melting ; and some earthy and other bodies infusible by or- 
dinary methods are liquefied by the same means. The shock is pain- 
ful and dangerous. When the communication between the points of 
charcoal is made in rarefied air, the annihilation of the opposite elec- 
tricities takes place at some inches’ distance, producing a stream of 
deep purple light. 
136. When the poles of the Voltaic apparatus are connected by a 
steel wire, it acquires magnetic properties; and if by a platinum or 
other metallic wire, that wire exhibits numerous magnetic poles, which 
attract and repel the common magnetic needle. This very curious 
fact was first observed by Professor Oersted, of Copenhagen. 
137. On immersing the wires from the extremes of this apparatus 
into water, it is found that the fluid suffers decomposition, and that 
oxygen gas is liberated at the positive wire or pole, and hydrogen gas 
at the negative pole. 
All other substances are decomposed with similar phenomena, the 
inflammable element being disengaged at the negatively electrical sur- 
face ; hence it would appear, upon the principle of similarly electri- 
fied bodies repelling each other, and dissimilarly electrified bodies at- 
tracting each other, (96) that the inherent or natural electrical state 
of the inflammable substances is positive, for they are attracted by the 
negative or oppositely electrified pole ; while the bodies, called sup- 
porters of combustion, or acidifying principles, are attracted by the 
positive pole, and, therefore, may be considered as possessed of the 
negative power. 
138. When bodies are thus under the influence of electrical decom- 
position, their usual chemical energies are suspended, and some verj 
curious phenomena are observed, which may he illustrated by the fol- 
lowing experiments. 
Fill the glass tubes a a, which 
are closed at top and open at bottom, 
with infusion of violets, or red cab- 
bage, and invert them in the basins 
b b, containing a solution of Glau- 
ber’s salt, and connected by the 
glass tube c, also containing the blue 
infusion. p and n are platinum 
wires, which pass into the tubes 
nearly to the bottom, and which are 
to be connected with the positive 
and negative extremities of the Vol- 
taic apparatus. It will be found that 
oxygen is evolved at the wire r, 
and hydrogen at n, derived from the 
decomposition of the water. The 
Combustion 
and fusion *f 
metals. 
Magnetism 
resulting from 
galvanism. 
Decomposi- 
tion of water. 
Combustible 
constituents, 
join in the ne- 
gative pole. 
Explanation. 
Supporters of 
combustion 
are attracted 
to the positive 
pole. 
Chemical 
union destroy- 
ed by galva- 
nism. 
Apparatus fer 
illustrating 
this power. ELECTRICITY. 
Glauber’s salt, which consists of sulphuric acid and soda, will also be 
decomposed ; and the blue liquor will be rendered red in the positive 
vessel, by the accumulation of sulphuric acid, and green in the negative, 
by the soda, while the acid and alcali will each traverse the tube c 
without uniting, in consequence of being under the influence of elec- 
trical attraction. 
139. The most difficultly decomposable compounds may be thus re- 
solved into their component parts by the electrical agency ; by a weak 
power the proximate elements are separated, and by a stronger power 
these are resolved into their ultimate constituents. (51). 
140. All bodies which exert powerful chemical agencies upon each 
other when freedom of motion is given to their particles, render each 
other oppositely electrical when acting as masses. Hence Sir II. Davy, 
the great and successful investigator of this branch of chemical philoso- 
phy, has supposed that electrical and chemical phenomena, though in 
themselves quite distinct, may he dependent upon one and the same 
power, acting in the former case upon masses of matter in the other 
upon its particles. 
141. The power of the Voltaic apparatus to communicate diver- 
gence to the electrometer, is most observed wrhen it is wrell insulated 
and filled with pure water ; but its power of producing ignition and of 
giving shocks, and of producing the other effects observed when its 
poles are connected, ai'e much augmented by the interposition of dilute 
acids, which act chemically upon one of the plates : here, the insula- 
tion is interfered with by the production of vapour, hut the quantity of 
electricity is much increased, a circumstance which may, perhaps be 
referred to the increase of the positive energy of the most oxidable 
metal by the contact of the acid. In experiments made with the great 
battery of the Royal Institution, it has been found that 120 plates ren- 
dered active by a mixture of one part of nitric acid and three of waiter, 
produced effects equal to 480 plates rendered active by one part of ni- 
tric acid and fifteen of water. 
142. In the Voltaic pile, the intensity of the electricity increases 
with the number of alternations, but the quantity is increased by exten- 
ding the surface of the plates. Thus, if a battery, composed of thirty 
pairs of plates two inches square, be compared with another battery of 
thirty pairs oftwmlve inches square, charged in the same way, no differ- 
ence will be perceived in their effects upon bad or imperfect conduc- 
tors ; their powers of decomposing water and of giving shocks will be 
similar ; but upon good conductors the effects of the large plates w ill 
be considerably greater than those of the small : they will ignite and 
fuse large quantities of platinum wire, and produce a very brilliant 
spark between charcoal points. The following experiment well illus- 
trates the different effects of quantity and intensity in the Voltaic appa- 
ratus. 
Immerse the platinum wires connected with the extremity of a 
charged battery composed of twelve-inch plates into water, and it will 
be found that the evolution of gas is nearly the same as that occasioned 
by a similar number of two-inch plates. Apply the moistened fingers 
to the wires, and the shock will be the same as if there were no con- 
nexion by the water. While the circuit exists through the human bo- 
dy and the water, let a wire attached to a thin slip of charcoal be made 
to connect the poles of the battery, and the charcoal will become 
Ravy’a idea 
of the connec- 
tion between 
chemical at- < 
traction & gal- 
vanism. 
Circumstan- 
ces promoting 
the power of 
the voltaic ap- 
paratus. 
Arrangement 
for intensity 
_t,»r quantity. 
Experimental 
illustration. ELECTRICITY. 
?i vuily ignited. The water and the animal substance discharge the elec- 
tricity of a surface probably not superior to their own surface of con- 
tact with the metals ; the wires discharge all the residual electricity of 
the plates ; and if a similar experiment be made on plates of an inch 
square, there will scarcely be any sensation when the hands are made 
to connect the ends of the battery, a circuit being previously made 
through water; and no spark, when charcoal is made the medium of 
connexion, imperfect conductors having been previously applied. 
These relative effects of quantity and intensity were admirably il- 
lustrated by the experiments instituted by Mr. Children, who con-i 
structed a battery, the plates of which were two feet eight inches' 
wide, and six feet high. They were fastened to a beam suspended by 
counterpoises from the ceiling of his laboratory, so as to be easily im- 
mersed into or withdrawn from the cells of acid. The effects upon 
metallic wires and perfect conductors were extremely intense ; but up- 
on imperfect conductors, such as the human body, and water, they 
were feeble.—Phil. Trans., 1815, p. 363. 
143. When the extremes of a battery composed of large plates are 
united by wires of different metals, it is found that some are more easily 
ignited than others, a circumstance which has been referred to their 
conducting powers : thus, platinum is more easily ignited than silver, 
and silver than zinc. If the ignition be supposed to result from resis- 
tance to the passage of electricity, we should say that the zinc conduct- 
ed better than silver, and the silver than platinum. 
144. An important improvement has been suggested in the construc- 
tion of the Voltaic apparatus by Dr. Wollaston, {Annals of Philosophy, 
Sept. 1815,) by which great increase of quantity is obtained without 
inconvenient augmentation of the size of the plates : it consists in ex- 
tending the copper plate, so as to oppose it to every surface of the 
Childrcn’a 
battery. 
Metallic fu- 
sion. 
Wollaston's 
improvement. ELECTRICITY. 
zinc, as seen in the annexed cut. a is the rod of wood to which the 
plates are screwed ; bb the zinc plates connected as usual with the 
copper plates cc, which are doubled over the zinc plates, and opposed 
to them upon all sides, contact of the surfaces being prevented by 
pieces of wood or cork placed at dd. 
With a single pair of plates of very small dimensions constructed up- 
on this principle, Dr. W'ollaston succeeded in fusing and igniting a fine 
platinum wire. From the experience which 1 have had of this con- 
struction, I am inclined to consider it the most (economical and useful 
form of the Voltaic apparatus ; certainly, at least, it is so for all those 
researches in which there is an occasional demand for quantity as well 
as intensity of electricity. 
145. The theory of the Voltaic pile is involved in many difficulties. 
The original source of electricity appears to depend upon the contact 
of the metals, for we know that a plate of silver and a plate of zinc, 
or of an}r other difficultly and easily oxidable metals, become negative 
1 and positive on contact. The accumulation must be referred to indue- 
ffow, which takes place in the electrical column (129) through the 
very thin stratum of air or paper, and through water when that fluid 
is interposed between the plates. Accordingly we observe that the 
apparatus is in the condition of the series of conductors with interpos- 
ed air (112) and of the Leyden phials (118). When the electric co- 
lumn is insulated the extremities exhibit feeble negative and positive 
powers, but if either extremity be connected with the ground, the 
electricity of its poles or extremities is greatly increased, as may be 
shown by the increased divergence of the leaves of the electrometer 
which then ensues. 
146. As general changes in the form and constitution of matter are 
connected with its electrical states, it is obvious that electricity must 
be continually active in nature. Its effects are exhibited on a magni- 
ficent scale in the thunder-storm, which results from the accumulation 
of electricity in the clouds, as was first experimentally demonstrated 
by Dr. Franklin, who also first showed the advantage of pointed con- 
ductors as safeguards to buildings. In these cases the conducting rod 
or rods should be of copper or iron, and from half to three-fourths 
of an inch diameter. Its upper end should he elevated three or four 
feet above the highest part of the building, and all the metallic parts 
of the roof should he connected with the rod, which should be per- 
fectly continuous throughout, and passing down the side of the build- 
ing, penetrate several feet below its foundation, so as always to be im- 
mersed in a moist stratum of soil, or if possible, into water. The 
leaden water-pipes attached to houses often might he made to answer 
the purpose of conductors, especially when thick enough to resist fu- 
sion. 
During a thunder-storm the safest situation is in the middle of a 
room, at a distance from the chimney, and standing upon a woollen rug, 
which is a nonconductor. Blankets and feathers being nonconductors, 
bed is a place of comparative safety, provided the bell-wires are not 
too near, which are almost always melted in houses struck by lightning. 
When out of doors, it is dangerous to take shelter under trees : the 
safest situation is within some yards of them, and upon the dryest spot 
that can be selected. 
The discharge of electricity in a thunder-storm is sometimes only 
from cloud to cloud: sometimes from the earth to the clouds; and 
The most cco 
nomical&use- 
ul form. 
Voltaic pile 
operates upon 
the principle 
of induction. 
Electricity 
continually 
active in na- 
ture. 
Lightning 
rods. 
discharge of 
lightning. ELECTRICITY. 
sometimes from the clouds to the earth, as one or other may he posi- 
tive or negative. When aqueous vapour is condensed, the clouds 
formed are usually more or less electrical; and the earth below them 
being brought into an opposite state, by induction, a discharge takes 
place when the clouds approach within a certain distance, constituting 
.lightning ; and the undulation of the air, produced by the discharge, is 
the cause of thunder, which is more or less intense, and of longer or 
shorter duration, according to the quantity of air acted upon, and the 
di stance of the place, where the report is heard from the point of the 
discharge. It may not be uninteresting to give, a further illustration of; 
this idea ; electrical effects take place in no sensible time ; it has been 
found that a discharge through a circuit of four miles is instantaneous ; 
but sound moves at the rate of about twelve miles in a minute. Now, 
supposing the lightning to pass through a space of some miles, the ex- 
plosion will be first heard from the point of the air agitated, nearest to 
the spectator; it will gradually come from the more distant parts of 
the course of the electricity, and last of all, will he heard from the re- 
mote extremity; and the different degrees of the agitation of the air, 
and likewise the difference of the distance, will account for the differ- 
ent intensities of the sound, and its apparent reverberations and changes. 
“ In a violent thunder-storm, when the sound instantly succeeds the 
flash, the persons who witness the circumstance are in some danger; 
when the interval is a quarter of a minute, they are secure.”—Davy’s 
Elements, p. 139. 
147. A variety of electrical apparatus has been devised to illustrate 
the operation of conductors for lightning, and the advantage of points 
over balls ; the simplest consists of a model of a house having a con- 
ductor with a break in it, in which some inflammable matter should be 
placed ; the lower end of the conductor should be communicated with 
the exterior of a charged Leyden phial, the knob of which, brought 
over its upper end, will then represent a thunder-cloud. If the con- 
ductor be pointed, it will he slowly discharged; if surmounted by a 
hall, there will be an explosion, and the combustibles probably inflam- 
ed. 
148. The coruscations of the aurora borealis are also probably elec- 
trical, and much resemble flashes of electric light traversing rarefied 
air. The water-spout may be referred to the same source, and is pro- 
bably the result of the operation of a weakly electrical cloud, at an 
inconsiderable elevation above the sea, brought into an opposite electri- 
cal state : and the attraction of the lower part of the cloud, for the sur- 
face of the water, may be the immediate cause of this extraordinary 
phenomenon. 
149. In the gymnotus or electric eel, and in the torpedo or electric ray, 
are arrangements, given to those remarkable animals for the purposes of 
defence, which certain forms of the Voltaic apparatus much resemble, 
for they consist of many alternations of different substances. These 
electrical organs are much more abundantly supplied with nerves than 
any other part of the animal, and the two frequent use of them is suc- 
ceeded by debility and death.—Todd, Phil. Trans., 1817. 
That arrangements of different organic substances arc capable of 
producing electrical effects, has been shown by various experimenta- 
lists. If the hind legs of a frog he placed upon a glass plate, and the 
crural nerve dissected out of one. made to communicate with, the other, 
Mode of deter- 
mining its dis- 
tance. 
Apparatus to 
shew the ope.- 
ration of light- 
ning coudueJ 
tors. 
Aurora l>or?s - 
lis & water 
spout. 
(•Electrical 
t fishes. ' 
f Arrangements 
of organic sub- 
stances admit 
: of producing 
electrical ef- 
■ f«ct». ELECTRICITY. 
it will be found, upon making occasional contacts with the remaining 
crural nerve, that the limbs of the animal will he agitated at each con- 
tact. These circumstances have induced some physiologists to suppose 
that electricity may be concerned in some of the most recondite phae- 
nomena of vitality, and Dr. Wollaston, Sir E. Home, and myself, have 
made some experiments tending to confer probability on this idea.— 
Phil. Trans., 1809. 
150. We have as yet no plausible hypothesis concerning the cause of 
electrical phsenomena, though the subject has engaged the attention of 
the most eminent philosophers of Europe. They have been by some 
referred to the presence of a peculiar fluid existing in all matter, and 
exhibiting itself by the appearances which have been described, when 
ever its equilibrium is disturbed, presenting negative and positive elec- 
tricity when deficient and when redundant. Others have plausibly ar- 
gued for the presence of two fluids, distinct from each other. Other? 
have considered the effects as referable to peculiar exertions of the at- 
tractive powers of matter, and have regarded the existence of any dis- 
tinct fluid or form of matter to be as unnecessary to the explanation of 
the phenomena, as it is in the question concerning the cause of gravi- 
tation. 
151. When the flame of a candle is placed between a positive and 
negative surface, it is urged towards the latter ; a circumstance which 
has been explained upon the supposition of a current of electrical mat- 
’ ter passing from the positive to the negative pole ; indeed, it has been 
considered as demonstrating the existence of such a current of matter. 
But if the flame of phosphorus he substituted for that of a candle, it 
takes an opposite direction ; and, instead of being attracted towards the 
negative, it bends to the positive surface. It has been shown that in- 
flammable bodies are ahvays attracted by negative surfaces, and acid 
bodies, and those in which the supporters of combustion prevail, 
are attracted by positive surfaces (137.) Hence the flame of the can- 
dle throwing off carbon, is directed to the negative pole, while that of 
phosphorus forming acid matter goes to the positive, consistently with 
the ordinary laws of electrochemical attraction.—Phil. Trans., 1814. 
152. There are other experiments opposed to the idea that electri- 
city is a material substance. If we discharge a Leyden phial through a 
quire of paper, the perforation is equally burred upon both sides, and 
not upon the negative side only, as would have been the case if any ma- 
terial body had gone through in that direction. The power seems to 
have come from the centre of the paper, as if one half of the quire had 
been attracted by the positive, and the other by the negative surface. 
153. When a pointed metallic wire is presented towards the conduc- 
tor of the electrical machine, in a darkened room, a star of light is ob- 
served when the conductor is positive, hut a brush of light when it is 
negative ; a circumstance which has been referred to the reception of 
the electric fluid in the one case, and its escape in the other. In the 
Voltaic discharge the same appearances are evident upon the charcoal 
point, rays appearing to diverge from the negative conductor, while up- 
on the positive a spot of bright light is perceptible. But these affec- 
tions of light can scarcely be considered as indicating the emission or re - 
epption of any specific form of matter. 
Electricity 
concerned in 
the phenome- 
na of vitality. 
Theories. 
Experiments 
seeming to fa- 
vour one more 
than another. 
Experiments 
in opposition 
to electricity 
being materi- 
al. 
One of a con- 
trary tenden- 
cy- radiant matter. 
CHAPTER II. 
of radiant or imponderable matter. 
154. Of the substances belonging to our globe, some are of so subtile 
a nature as to require minute and delicate investigation to demonstrate , 
their existence ; they can neither be confined, nor submitted to thet 
usual modes of examination, and are known only in their states of 
tion as acting upon our senses, or as producing changes in the more 
gross forms of matter. They have been included under the general 
term of Radiant or Imponderable Ethereal Matter, which as, it pro- 
duces different phaenomena, must be considered as differing either in 
its nature or affections. Respecting the nature of these phaenomena, 
two opinions have been entertained, and each ably supported. It has 
been supposed by Huygens and Descartes, that they arise from vibra- 
tions of a rare elastic medium which fills space ; while Newton has< 
considered them as resulting from emanations of particles of matter. 
The other forms of matter are tangible and ponderable, and, there- 
fore, easily susceptible of accurate examination; they may be consi- 
dered as resulting from the mutual agencies of heat and attraction, and 
are comprehended under the three classes of Solids, Liquids, and 
Gases. 
Too subtile for 
the Usual 
modes of exa- 
mination. 
Leading The- 
ories of Des- 
cartes and 
Newton, 
Section I. Of the Effects of Radiant Matter in producing 
the Phenomena of Vision. 
155. The minute investigation of those laws of light which relate 
to its motion, and effects in producing vision, constitutes a branch of 
of the science of Optics, and therefore belongs to Mechanical Philo- 
sophy ; it is, however, requisite that some of them should partially be 
considered as bearing upon important questions of chemical inquiry. 
The phenomena of vision are produced either by bodies inherently 
luminous, such as the sun, the fixed stars, and incandescent substances ; 
or they are referable to the reflection of light from the surfaces of bo- 
dies. It is thus that the objects around us are visible by reflecting the 
sun’s rays, in the day-time, but become lost in obscurity when that lu- 
minary sinks beneath the horizon. 
156. The manner in which the eye is affected by luminous bodies 
shows that light is transmitted in right lines, and eArery right line drawn 
from a luminous body to the eye is termed a ray of light, and as a con- 
geries of rays possesses the same properties as the single ray, the same 
abstract term is frequently employed to designate the congeries. 
Vision. 
Light trans- 
mitted in light 
lines. PHENOMENA *P VISION. 
157. The discoveries of lloemer, (Phil. Trims., Vol. xii.) and of 
Bradley, (Phil. Trans., Vol. xxxv. and xlv.) have shown that light is 
about eight minutes and thirteen seconds in passing from the sun to the 
earth, so that it may be considered as moving at the rate of 200,01)0 
miles in a second. 
158. Some bodies intercept light or are opaque : others allow its 
transmission, or are transparent; and there are gradations from per- 
fect opacity to nearly perfect transparency. It is probable that opaci- 
ty results from the attraction of the substance for light, and not from 
its density, for it can scarcely be supposed that the particles of bodies 
should not be far enough distant to allow of the passage of light. New- 
ton supposes the particles of transparent bodies to be of uniform densi- 
ty and arrangement, and attracting the ray of light equally in every di- 
rection, they suffer it to pass through them without obstruction; 
whereas, in opaque bodies, the particles are either of unequal densi- 
ty or irregularly arranged, and the light being unequally attracted, can- 
not therefore penetrate the body. 
159. When a ray of light passes through the same medium, or when 
it passes perpendicularly from one transparent medium into another, 
it continues to move without changing its direction ; but, when it pass- 
es obliquely from one medium into another of a different density, it is 
thrown more or less out of its old direction, and is said to be refracted. 
The refraction is towards the perpendicular when the ray passes into 
a denser medium, and from the perpendicular when it passes into a 
rarer medium. The medium in which the rays of light are caused to 
approach nearest to the line perpendicular to its surface, is said to have, 
the greatest refractive density. 
160. The density of bodies is by no means the only circumstance 
that effects their refractive power, it also depends upon their chemi- 
cal nature ; and generally speaking those substances have the greatest 
refractive power which are combustible, or which contain an inflam- 
mable basis : the refractive power of compounds is not the mean de- 
duced from that of their components ; which, however, it generally is 
in mere mixtures. The following table exhibits the refractive powers 
of several gaseous and solid bodies, from the experiments of Biot and 
Arago, and from Newton’s Optics : 
Rate of lights 
motion. 
JTewtbn’sidea 
ef opacity & 
transparency. 
Effect of dif- 
ferent densi- 
ties in the me- 
fa, 
Refractive 
•Power de- 
pends on the 
chemical na- 
ture as well as 
density. 
Refractive 
power of com- 
pounds not the 
mean of that 
possessed by 
their constitu- 
ents. 
Atmospheric air 
. . . . 1.00000 
Oxygen 
Nitrogen 
, . . . 1.03408 
Hydrogen 
Ammonia 
Carbonic acid 
Carburetted hydrogen 
. . . 2.09270 
Muriatic acid gas 
. . . 1.19626 
Muriatic ether, in gaseous state . . . . 
. . . 1.71344 
Water 
Alcohol 
, . . . 2.2223 
Olive oil 
, . . . 2.7684 
Diamond 
Gum Arabic 
Table ofthe re- 
fractive pow- 
ers of somebo- 
dies. 
5ieflccts4 
light. 
161. When the rays of arrive at the surfaces of bodies, a part 
of them, and sometimes nearly the whole, is tjtfown bach, or reflected> REFRACTION' OP LIGIIX. 
and the more obliquely the light falls upon the surface, the greater in 
general is the reflected portion. In these cases the angle of reflection 
is always equal to the angle of incidence. 
Let a a represent pencils of light falling upon the surface of a polish- 
ed piece of glass b, the perpendicular pencil w ill pass on in a straight 
line to d. Of the oblique pencil, one portion will enter the glass and 
suffer refraction towards the perpendicular as at b, and re-entering the 
atmosphere, it will bend from the perpendicular, and re-assume its 
former direction, as at c. Another portion of the oblique pencil will be 
reflected at an angle equal to that of its incidence, as at e. 
162. When a ray of light passes through an oblique angular crystal • 
line body, it exhibits peculiar phenomena ; one portion is refracted in 
the ordinary way ; another suffers extraordinary refraction, in a plane 
parallel to the diagonal joining the two obtuse angles of the crystal ; so 
that objects seen through the crystal appear double. Transparent 
rhomboids of carbonate of lime, or Iceland crystal, exhibit this pheno- 
menon of double refraction particularly distinct. 
If a ray of light, which has thus suffered double refraction, be receiv- 
ed by another crystal, placed parallel to the tirst, there will be no new 
division of the rays ; but if it he placed in a transverse direction, that 
part of the ray which before suffered ordinary refraction will now un- 
dergo extraordinary refraction, and reciprocally that which underwent 
extraordinary refraction now suffers ordinary refraction. 
If the second crystal be turned gradually round in the same plane, 
when it has made a quarter of a revolution there will be four divisions 
of the ray, and they will be reduced to tAvo in the half ofthe revolution ; 
so that the refracting power appears to depend upon some relation of 
the position of the crystalline particles. 
163. When light is reflected from bodies, it retains, under many cir- 
cumstpnccs, its former relations to the refractive poAver of transparent 
Double re- 
fraction. 
Ordinary & 
extraordinary' 
refraction. 
Refracting 
power seems 
dependant up• 
•on some posi- 
tion of crystal - 
line particle*. POLARISATION OF LIGHT. 
media ; but, in certain cases, at angles differing for different substan- 
ces, the reflected rays exhibit peculiar properties, analogous to those 
which have suffered extraordinary refraction. Thus, if the flame of a 
taper reflected at an angle of 52° 45' from the surface of water, be 
viewed through a piece of doubly refracting spar, one of the images 
will vanish every time that the crystal makes a quarter of a revolution. 
164. When a ray of light is made to fall upon a polished glass surface, 
o at an angle of incidence of 35° 25', the angle of reflection will be equal to 
that of incidence. Let us suppose another plate of glass so placed that 
the reflected ray will fall upon it at the same angle of 35° 25'; this se- 
cond plate may be turned round its axis without varying the angle 
which it makes with the ray that fills upon it. A very curious cir- 
cumstance is observed as this second glass is turned round. Suppose 
I the two planes of reflection to be parallel to each other, in that case 
the ray of light is reflected from the second glass in the same manner 
as from the first. Let the second glass be now turned round a quad- 
rant of a circle, so as to make the reflecting planes perpendicular to each 
other: now, the whole of the ray will pass through the second glass, 
and none of it will be reflected. Turn the second glass round another 
quadrant of a circle, so as to make the reflecting planes again parallel, 
and the ray will again be reflected. When the second glass is turned 
round, three quadrants, the light will be again transmitted, and none of 
it reflected. Thus, when the reflecting planes are parallel, the light 
is reflected, but when they are perpendicular the light is transmitted. 
This experiment proves, that, under certain circumstances, light can 
penetrate through glass when in one position, but not in another. This 
curious fact was first observed by Malus, who accounted for it by sup- 
posing the particles of light to have assumed a particular position as a 
needle does when under the influence of a magnet, and hence he called 
this property of light, its Polarisation. (Thomson’s System, Vol. i. p. 
16.) It has since been studied with laborious diligence by Dr. Brew- 
ster, and by M. M. Arago and Biot,—Phil. Trans. 1813, 1814, 1815, 
1816, 1817.—Annales dc Chimie, tom. 94.—Traite de Physique. 
165. If plates of mica, and certain other crystallized substances, be 
placed between the glasses employed in the above experiments, so that 
the reflected rays may traverse them in passing from one surface to the 
other, it will be found that under certain circumstances, the image of 
the candle will remain visible ; in other words, the light will be depo- 
larised in passing through the crystallized medium. Common glass is 
generally incapable of depolarising the ray, but it acquires the depola- 
rising power when submitted to pressure, or heated, or when it has 
been heated and very suddenly cooled ; the influence of its particles 
upon those of light becoming then analogous to crystallized bodies. 
166. That a sunbeam, in passing through a dense medium, and espe- 
cially through a triangular prism of glass, gives rise to a series of bril- 
liant tints similar to those of the rainbow, was known in the earliest ages, 
but itrequired the sagacity of Newton to develope the cause of the phe- 
nomenon. He proved, that light consists of rays differing from each 
other in their relative refrangibilities ; and, guided by their colour con- 
sidered their number as seven : red, orange, yellow, green, blue, indi- 
go, and violet. If the prismatic colours, or spectrum, be divided into 
360 equal parts, the red rays will occupy 45 of these parts, the orange 
27, the yellow 48, the green 60, the blue 60, the indigo 40, and the 
Angle of inci- 
dence eqaul to 
the angle of 
reflection. 
Curious in- 
stance of Oie 
transmission 
and reflection 
»f light. 
Polarisation 
of light. I 
Prismatic co- , 
hurs. 
f PRISMATIC REFRACTION. 
57 
violet 80. Of these rays the red being least refrangible, fall nearest that 
spot which they would have passed to, had they not been refracted ; 
while the violet rays being most refrangible, are thrown to the greatest 
distance ; the intermediate rays, possess mean degrees of refrangibility. 
167. These differently-coloured rays are not susceptible offurther de- 
composition, by any number of refractions, but when they are collected 
into a focus they re-produce white light. Upon these phamomena is 
founded the Newtonian theory of colours, which supposes them to depend 
upon the absorption of all rays, excepting those of the colour observed. 
Thus green bodies reflect the green rays and absorb the others. All the 
rays are reflectedby white bodies, and absorbed by those which are black. 
Newton's the- 
ory of colours. 
Section II. Of the Operation of Radiant Matter in producing Heat. 
168. If a solar beam be refracted by a prism, and the coloured image re- 
ceived upon a sheet of paper it will be found, on moving the hand gently 
through it, that there is an evident increase of temperature towards the 
red ray. This fact seems to have been first noticed by Dr. Hutton (Dis- 
sertation on Light and Heat, p. 39;) but it is to Dr. Herschel {Phil. Trans. 
1800,) that we are indebted for a full investigation of the subject. If the j 
coloured rays be thrown successively upon delicate thermometers, it will t 
be found, that if the heating power of the violet rays be considered = 16,1 
that of the green rays will be = 26, and of the red = 56. These circum- 
stances suggested the possibility of the heating power of the spectrum ex- 
tending beyond the red ray ; and on applying a thermometer just out of 
the red ray, and beyond the limits of the visible spectrum, this was found 
to be the case. A thermometer in the red ray rose 7° in ten minutes, but [ 
just beyond the red ray the rise was =9°. It is evident, therefore, that,: 
independent of the illuminating rays, there are others which produce in-1 
crease of temperature, and these from their increase towards the red ray, 
and from the spot which they principally occupy in the refracted conge- 
ries, are possessed of less refrangibility than the visible rays. 
Dr. Herschel’s experiments were repeated, with nearly similar re- ] 
suits, by Sir H. Englefield, in 1802, and by Mr. Berard, in 1813 (Thom- \ 
son’s Annals, ii, 163,) who found the maximum of heat to exist just ati 
the extremity of the red ray. 1 
169. That these calorific rays are susceptible of refraction and re- < 
flection, is proved by the intense heat produced when the solar rays are J 
concentrated into a focus by a lens, or by a concave mirror. 
170. The radiant matter, emitted by terrestial bodies at high tempe-. 
ratures, agrees in many of its properties with that constituting the solar' 
rays, but in others it presents apparent peculiarities : the investigation, 
of this subject constitutes a beautiful department of philosophic inquiry, j 
The effect we perceive in approaching a fire chiefly results from radi- 
ation and is little connected with the immediate conducting power of the 
air ; and if a concave metallic mirror be held opposite the fire a heating 
and luminous focus will be obtained. The affections of terrestrial ra- ] 
diant matter are best demonstrated by employing two concave mirrors1 
of planished tin or plated copper, placed at a distance of about ten feet 
Relative tem- 
perature of 
the prismatic 
rays. 
Calorific, and 
colorific rays 
separated by 
the prism. 
Maximum of 
temperature 
at the extre- 
mity of the red 
ray. 
Concentration 
of these tem- 
peratures. 
Terrestial 
and solar ra- 
diant matter 
have each 
some peculia- 
rities differing 
from the other. 
Reflected ca- 
loric. RADIATION OF HEAT. 
asunder. (Pictet, Essais de Physique.') Under these circumstances 
when a thermometer is in the focus of one of the mirrors, it will be found 
se nsible to the effects of a heated body placed in the focus of the opposed 
mirror ; and that the effect is produced by reflection, and not by mere di- 
rect radiation, is proved, either by drawing the thermometer out of the fo- 
cus towards the opposed mirror, or by placing a screen betw een the ther- 
mometer and its mirror, w’hen diminution of temperature is in either case 
Field’s expe- 
riment. RADIANT MATTER. 
indicated. In these experiments the differential thermometer (66) is 
most advantageously employed, and the mirrors may be placed opposite 
each other on theground, orvertically suspended as in the woodcut, where 
a a represent the mirrors, b a pan of hot charcoal, c an air thermometer. 
171. If the flame of a candle be placed in the focus of one mirror, a 
heating and luminous focus is obtained from the other : but if a plate of' 
glass be now interposed between the two mirrors, the rays of heat arei 
arrested, while those of light, freely passing through the glass, are col- 
lected, as usual in the opposite focus. It has hence been concluded that 
there is a difference between solar and terrestrial heat; the rays of the 
former passing through glass without heating it ; while the rays of the 
latter are stopped by glass, and it becomes hot when opposed to them. 
—(Scheele’s Experiments on Air and Fire.) But the rays of burn- 
ing bodies may in many instances be shown to pass through glass with 
great facility ; thus a bright gas flame affords a heating as well as a lumi- 
nous focus, when its rays are concentrated by a double convex lens, up- 
on the bulb of an air thermometer.—Brande, Phil. Trans. 1820. p. 27. 
172. In these experiments upon the radiation of terrestrial heat, the 
temperature excited by the radiant matter appears always relative to 
that of the heated or radiating body ; and if we assume that all bodies 
are constantly throwing oft' radiant matter, the effects of temperature 
which it produces when condensed or collected into a focus by a con- 
cave mirror, will bear a relation to the source ; for the particles may be 
conceived to move with such velocity as not to be affected by circumja- 
cent bodies, or by the circumambient air. Thus, white-hot iron produ- 
ces a greater effect upon the focal thermometer than that which is only 
red-hot, and red-hot iron causes a greater effect than hot water ; a bo- 
dy of the same temperature as the thermometer causes no change in it; 
hut cold bodies produce an effect of cold, because the particles which 
they radiate, when stopped by impinging upon the thermometer-bulb, 
are of a lower temperature. 
173. Radiation has by some been accounted for upon the idea of the 
heated body producing undulations in the air, something analogous to < 
the waves excited by sonorous bodies ; but the different phenomena] 
of prismatic refraction and of solar and terrestrial radiation are not sa-1 
tisfactorily explained upon such an hypothesis. 
Newton endeavoured to explain the different refrangihility of the 
rays of light, by supposing them composed of particles of different siz-' 
es ; and adopting this hypothesis, we should say, that the particles 
of red light were largest, those of violet light smallest. The heating 
rays (168) would consist of particles yet larger than those producing 
colour ; and the smallest particles, or most attenuateu radiant matter, 
would be that which produces certain chemical changes (180.)—(New- 
ton’s Optics.) Upon this hypothesis, too, it would appear that the 
particles of terrestrial heat are of so large a size as to be partially ar- 
rested in their progress by glass and other transparent bodies which al- 
low a free passage to solar radiant matter. 
Newton has also put the query, “ whether light and common matter 
are not convertible into each other ?” And if we consider sensible heat 
in bodies to depend upon vibrations of their particles, a certain intensi- 
ty of vibrations may send oft’ particles into free space ; and particles 
moving rapidly in right lines, may, in losing their own motion, commu- 
nicate a vibratory motion to the particles of terrestrial bodies.—Da- 
vy’s Elements, p. 215. 
Separation of 
light from cu • 
loric. 
Radiation 
considered as 
depending up- 
on the undula- 
tions of air. 
Newton’s idea 
of refrangib;- 
lity. RADIATION IN VACUO. 
Radiation in 
elastic media 
and the Torri- 
cellian va- 
cuum- 
174. Radiation goes on in all elastic 
media, and in the Torricellian and air- 
pump vacuum, as may be shown by igni- 
ting charcoal by means of the V oltaic bat- 
tery, placed in the focus of a small mirror 
confined in the exhausted receiver of the 
air-pump. Sir. H. Davy found thatthe re- 
ceiver being exhausted to , the ef- 
fect upon the thermometer in the oppo- 
site focus was nearly three times as great 
as when the air was in its natural state 
of condensation, a is the receiver, b b 
the insulated wires connected with the 
voltaic apparatus igniting the charcoal 
in the focus of the upper mirror c. In 
the focus of the lower mirror d is the 
thermometer e. 
175. It has long been known, in re- 
gard to solar rays, that their heating 
effect depends much upon the colour 
of the surfaces upon which they im- 
pinge, and that black and dark bodies are more heated than those 
which are white or of light tints, circumstances dependent upon ab- 
sorption and reflection. 
Professor Leslie has shown that the phenomena of terrestrial radia- 
tion are connected with the nature of the radiating surface ; and that 
those surfaces which are the best radiators of this heat are also gifted 
with the greatest absorbing power.—Leslie on Heat. 
Unmetallic and unpolished surfaces are the best radiators, and also 
the best receivers of radiant heat ; while polished metallic substances 
are the worst radiators, and have the lowest absorbing powers. In the 
experiments with the metallic mirrors, the whole nearly of the heat is 
reflected, and the mirror itself does not become warm : but if it be 
coated with any unpolished, and especially unmetallic coating, as with 
paper, or paint, the reflection is then scarcely perceptible and the 
mirror becomes hot from the absorption of the radiant matter. 
In Professor Leslie’s experiments it was found, that a clean metallic 
surface produced an effect = 12 upon the thermometer. When cov- 
ered with a thin coat of glue, its radiating power was so far increased 
as to produce an effect = 80 ; and, on covering it with lamp-black, it 
became = 100. 
In these cases of radiation, the colour of the surface does not inter- 
fere, and the different effects must be referred to the mechanical struc- 
ture of the radiating surface. White paper and lamp-black produce 
nearly the same effects ; and paper, coloured blue, red, yellow, and 
green, does not differ in radiating power from that which is white, 
provided the colour produces no change of texture in the paper. 
176. The connexion of the receptive with the radiating power is 
made obvious by coating the bulbs of thermometers with different 
substances. Thus, the effect of radiant heat upon a thermometer 
bulb covered with a thin coating of lamp-black being = 100 ; when 
the bulb is covered with silver-leaf the effect is only = 12. M. M. 
Dulong and Petit, in their valuable Memoir on Heat, which gained the 
Heating effect 
of solar rays 
with regard to 
superficial co- 
lours. 
Radiation of 
caloric in di- 
rectproportion 
to its degree of 
absorption. 
Radiation in- 
dependent of 
superficial co- 
lour- OP RADIANT OR IMPONDERABLE MATTER. 
61 
prize-medal of the Academy of Sciences for 1818, have detailed a 
variety of important facts upon the subject of the radiation of sur- 
faces. 
177. Upon the principle of the absorption of the solar rays by 
blackened surfaces, Mr. Leslie has constructed a photometer. It is i 
merely a very delicate and small differential thermometer, enclosed in1 
a thin and pellucid glass tube. One of the bulbs is of black glass, 
which when the instrument is suddenly exposed to light, becoming 
warmer than the clear bulb, indicates the effect by the depression of 
the fluid. (Leslie on Heat, p. 424.) A differential thermometer 
containing the vapour of ether, may also, in certain experiments, he 
advantageously used as a Photometric Thermometer.—Brande, Phil. 
Trans. 1820. 
178. It is obvious, from the above-mentioned facts, that all vessels’ 
intended to retain heat, should be clean and metallic, for polished me-J 
tallic surfaces have very low radiating powers ; whereas those vessels “ 
which are either to receive, or to radiate, should be blackened upon 
their surfaces. The knowledge of these properties is economically 
applicable in a variety of cases. 
Photometer of 
Leslie. 
Vessels in- 
tended to re- 
tain caloric 
shouldbecle&n 
and metallic. 
Section III. Of the Influence of Radiant Matter in producing Chemi- 
cal Changes. 
179. Radiant matter possesses considerable influence over the 
chemical energies of bodies. If a mixture of equal volumes of the 
gases called chlorine and hydrogen he exposed in a dark room, they 
slowly combine, and produce muriatic acid gas ; but, if exposed to 
the direct rays of the sun, the combination is very rapid, and often 
accompanied by an explosion. 
Chlorine and carbonic oxide have scarcely any tendency to combine, 
even at high temperatures, when light is excluded, but exposed to the 
solar rays they enter into chemical union. Chlorine has little action 
upon water, unless exposed to light; and, in that case, the water, 
which consists of oxygen and hydrogen, is decomposed. The hydro- 
gen unites with the chlorine to produce muriatic acid, and the oxygen is 
evolved in a gaseous form. 
180. These, and numerous other similar cases which might be ad- 
duced, show that radiant matter influences the chemical energies of 
bodies, independent of its heating powers. Scheele (Experiments on 
Air and Fire, p. 78, <£'c.) was the first who entered upon this curious 
investigation ; and many important facts connected with it have been 
more lately ascertained by Ritter, Wollaston, and Davy. Scheele 
threw the prismatic spectrum upon a sheet of paper, moistened with 
a solution of nitrate of silver, a salt quickly decomposed by the agen- 
cy of light. In the blue and violet rays the silver was soon reduced, 
producing a blackness upon the paper, but in the red ray scarcely any 
similar effect was observed. Wollaston and Ritter discovered that 
these chemical changes were most rapidly effected in the space which 
hounds the voilet ray, and which is out of the visible spectrum. 
Radiant mat. 
ter possesses 
considerable 
influence over 
the chemical 
energies of be* 
dies. 
.Produces 
chemical 
changes. PHOSPHORESCENT SUBSTANCES. 
Division of so- 
lar rays by re- 
fraction. 
181. It has been thus ascertained, that the solar beams are refrangible 
into three distinct kinds of rays ; the calorific, or heating rays ; the 
luminous, or colorific, rays, which produce vision and colour ; the de- 
composing rays, or those which have a tendency to interfere with thes. 
chemical constitution of bodies. 
In the prismatic spectrum these three sets of rays are imperfectly 
separated, and arranged according to their respective refrangibilities. 
The heating rays are the least refrangible, the colorific rays are pos- 
sessed of more refrangibility, and the decomposing, or, as some have 
called them, the deoxidizing rays, are the most refrangible. 
182. Sir H. Davy has observed, that certain metallic oxides, when 
exposed to the violet extremity of the prismatic spectrum, undergo a 
change similar to that which would have been produced by exposure 
to a current of hydrogen ; and that, when exposed to the red rays they 
acquire a tendency to absorb oxygen. (Elements of Chemical Philoso- 
phy.) In such general facts, he traces an analogy between the effects 
of the solar beam, and the agencies of electricity. In the Voltaic cir- 
cuit, the maximum of heat is at the positive pole, where the power of 
combining with oxygen is also given to bodies ; the agency of render- 
ing bodies inflammable is exerted at the opposite surface ; and similar 
chemical effects are produced by negative electricity, and by the 
most refrangible rays; and by positive electricity, and the rays 
which are least refrangible. 
183. It has been asserted by Morichini, and the experiment is said 
to have succeeded in other hands, that the prismatic spectrum is capa- 
ble of exciting the magnetic influence, and that a needle exposed to the- 
violet rays acquires polarity : this would point out a further analogy 
between the agencies of light and electricity. (136.) 
184. In nature the influence of the solar rays is very complex, and 
the growth, colour, flavour, and even the forms of many vegetables, 
are much dependent upon them. This is seen in many plants which 
are protected from the sun’s rays : celery and endive are thus cultiva- 
ted with the view of rendering them palatable ; and plants which are 
made to grow in a room imperfectly illuminated, always bend towards 
the apertures by which the sun’s rays enter. The changes too which 
vegetables effect upon the circumambient atmosphere are influenced by 
the same cause. 
In the animal creation, brilliancy of colour and gaudy plumage be- 
long to the tropical climates ; more sombrous tints distinguish the po- 
lar inhabitants ; and dull colours characterize nocturnal animals, and 
those who chiefly abide below the surface. 
Not perfectly 
exhibited in 
the prismatic 
spectrum. 
Analogy be- 
tween the ef- 
fect of the so- 
lar ray and 
that of elec- 
tricity. 
The violet ray 
«*t' the spec- 
trum capable 
•f exciting 
magnetic po- 
larity. 
Perfect vege- 
tation requires 
the influence 
of solar rays. 
Section IV. Of the Phenomena exhibited by Luminous and Incandes- 
cent Bodies, and of the Nature and Properties of Flame. 
185. There are many substances which, when heated to a certain 
point, become luminous without undergoing combustion, and such bo- 
dies are said to be phosphorescent. The temperatures which they re- 
quire for this purpose are various ; it generally commences at about 
P'nosphores- 
ctrut bodies- 400°, and may be said to terminate at the lowest visible redness. Some 
varieties of phosphate of lime, of fluorspar, of bituminous carbonate 
of lime, of marble, and sand, and certain salts, are the most remarkable 
bodies of this description. (Wedgwood, Phil. Trans. Vol. 82.) Their 
luminous property may be best exhibited by scattering them in coarse 
powder upon an iron plate heated nearly to redness. Oil, wax, sper- 
maceti, and butter, when nearly boiling, are also luminous. 
186. Another class of phosphorescent bodies have been termed so- 
lar phosphori, from becoming luminous when removed into a dark 
room after having been exposed to the sunshine. Of this description 
are Canton’s, Baldwin’s, and the Bolognian phosphorus. Canton’s 
phosphorus is prepared thus :—Calcine oyster-shells in the open fire 
for half an hour, then select the whitest and largest pieces and mix 
them with one third their weight of flowers of sulphur, pack the mix- 
ture closely into a covered crucible, and heat it to redness for an hour, 
When the whole has cooled, select the whitest pieces for use.—Phil. 
Trans. Vol. 58. 
Baldwin’s phosphorus is prepared by heating nitrate of lime to a 
dull red heat, so as to form it into a compact mass : and the Bolognian 
phosphorus, discovered by Vincenzio Cascariolo, a shoemaker of Bolog- 
na, is made by reducing compact sulphate of baryta to a fine powder, 
which is formed into cakes with mucilage, and these are heated to red- 
ness.—Aikin’s Dictionary, Art. Phosphori. 
Mr. B. Wilson has also made a variety ol curious experiments on so- 
lar phosphori; and, he has discovered the simplest and most effectual 
of these bodies, which may be obtained by closely observing the fol- 
lowing directions :—Take the most flaming coals off a brisk fire, and 
throw in some thick oyster-shells ; then replace the coals, and calcine 
them for an hour ; remove them carefully, and, when cold, it will be 
found that after exposing them for a few minutes to the light, they will 
glow in the dark with most of the prismatic colours.—Wilson on Phos- 
phori, p. 20. 
187. A third set of bodies, belonging to this class, are those which 
are spontaneously phosphorescent. Such are especially, the flesh of salt- 
water fish just before it putrefies, and decayed wood. The glow-worm, 
and the lantern-fly, are also luminous when alive ; and the hundred leg- 
ged worm, and some others, shine brilliantly when irritated. 
It appears from the experiments of Canton and of Dr. Hulme, {Phil. 
Trans. Vols. lix. xc. and xci.) that sea-fish become luminous in about 
twelve hours after death, that it increases till putrefaction is evident, 
and that it then decreases. Immersion in sea-water does not affect 
this luminous matter, on the contrary, the brine is itself rendered lu- 
minous ; but it is extinguished by pure water, and by a variety of sub- 
stances which act chemically upon the animal matter. 
188. Percussion and friction are often attended by the evolution of 
light as when flint pebbles, pieces of sugar, and other substances, are 
struck or rubbed together. 
189 From experiments in which air has been intensely heated, it 
has been concluded that gaseous matter is incapable of becoming lumi- 
nous ; for, though the temperature of air be such as to render solid bo- 
dies white hot, it does not itself become visible. (Wedgwood, Phil. 
Trans. 1792.) Flame, however, may, in general, be regarded as lu- 
minous gaseous matter. Hydrogen gas, probably, furnishes the purest 
PHENOMENA of phosphorescence. 
63 
Solarphospha- 
ri. 
Canton’s cota- 
pound. 
Baldwin’s and 
the Bolognian 
phosphorus. 
Wilson’s ex- 
periments. 
. Spontaneous 
Phosphori. 
1 Light from 
- percussion ov 
friction. 
Gases incapa- 
ble of becom- 
ing luminous. IS ATURE OF FLAM*. 
form of flame which can be exhibited ; for the flames of bodies which 
emit much light, derive that power from solid matter which is intense- 
ly ignited and diffused through them, and which, in ordinary flames, as 
of gas, tallow, wax, oil, fyc., consists of finely divided charcoal. 
190. The intensity of the heat of flames which are but little lumi- 
nous, as of hydrogen gas, spirit of wine, <$•£., may be shown by intro- 
ducing into them some fine platinum wire, which is instantly rendered 
white hot in those parts where the combustion is most perfect. It is 
even intensely ignited in the current of air above the flame, as may be 
shown by holding a piece of platinum-wire over the chimney of an 
Argand lamp fed with spirit of wine ; the high temperature of this 
current is also exhibited by the common expedient of lighting paper by 
holding it in the heated air which rushes out of a common lamp-glass. 
191. The high temperature of flame is further proved by certain 
cases of combustion without flame. Thus, if a heated wire of plati- 
num be introduced into any inflammable or explosive mixture, it will 
become ignited, and continue so till the gas is consumed ; but inflam- 
mation will, in most cases, only take place when the wire becomes 
white hot. This experiment is easily made by pouring a small quan- 
tity of ether into the bottom of a beer-glass, and holding, a piece of 
heated platinum wire a little above its surface ; the wire becomes red 
hot, but does not inflame the vapour of the ether till it acquires an in- 
tense white heat. 
The same fact is exhibited by putting a 
small coil of platinum wire round the wick 
of a spirit lamp, which, when heated, be- 
comes red hot, and continues so, as long as 
the vapour of the spirit is supplied, the 
heat never becoming sufficiently intense to 
produce its inflammation. 
192. Such being the nature of flame, it is 
obvious, that if we cool it by any means, we 
must at the same time extinguish it. This 
may be effected by causing it to pass through 
fine wire gauze, which is an excellent conductor and radiator of heat, 
and consequently possessed of great cooling power. If a piece of 
fine brass or iron wire-gauze be brought down upon the flame of a 
candle, or what answers better, upon an inflamed jet of coal gas, it 
will, as it were, cut the flame in half. That the cooled gaseous mat- 
ter passes through, may be shown by again lighting it upon the upper 
surface. 
193. The power, therefore, of a metallic tissue thus to extinguish 
flame, will depend upon the heat required to produce the combustion, 
as compared with that acquired by the tissue; and the flame of the 
most inflammable substances, and of those that produce most heat in 
combustion, will pass through a metallic tissue that will interrupt the 
flame of less inflammable substances, or those that produce little heat 
in combustion ; so that different flames will pass through at different 
degrees of temperature. 
194. The discovery of these facts, respecting the nature and pro- 
perties of flame, led Sir H. Davy to apply them to the construction 
of the Miners’’ safety lamp, which will be explained under the article 
Carburetted hydrogen gas. 
Hight and 
temperature 
of flame. 
Platinum wire 
lamp. 
Davy’s safety 
lamp. NOMENCLATURE. 
65 
195. The phenomena exhibited by phosphorescent and incandes- 
cent bodies, and in the process of combustion, have sometimes been 
explained upon the idea that the light and heat evolved, were pre- 
viously in combination with the substances, and that they are after- 
wards merely emitted, in consequence of decomposition ; and that the 
solar phosphori absorb light and again give it out unchanged. But it 
appears more probable that any particles violently repelled into space 
may become radiant matter, than that it should consist of a specific 
substance : thus, mechanical action, and chemical changes, may each 
tend to the emission of radiant matter ; and incandescence will result 
when the vibrations which heat occasions among the particles of bodies 
are of such violence as to cause their repulsion into space 
On the proper- 
ties of phos- 
phorescence 
and incandes- 
cence. 
CHAPTER III. 
©F THE SIMPLE SUPPOR.TERS OF COMBUSTION. 
196. The substances belonging to this class are characterized by 
possessing very energetic powers of combination in respect to the sim- 
ple inflammable bodies, and they are each of them capable of pro- 
ducing acids, whence they may also be termed acidifying princi- 
ples. When their compounds are submitted to electro-chemical de- 
composition, these elements are attracted by the positive surface ; 
hence their natural or inherent electrical states may be considered as 
negative. 
These acidifying, electro-negative supporters of combustion, are 
three in number: 
Acidifying 
principles. 
Electro nega- 
tive. 
1. Oxygen. 
2. Chlorine. 
3. Iodine. 
197. The following examples will serve to give some idea of the1 
principles of nomenclature generally adopted in chemistry. The 
above bodies in entering into combination with each other, and with the 
bodies described in Chapters IV and V., produce two classes of com- 
pounds. Those which are not acid, are usually distinguished by the 
termination ide, as oxide of chlorine, oxide of nitrogen, chloride of sul- 
phur, iodide of iron, 4-c. ; and where more than one compound of this 
kind is produced, the terminations ous and ic are used to designate the 
relative proportions of the supporters of combustion. Thus nitrogen 
forms two oxides ; that containing the smallest proportion of oxygen is 
Chemical fib-- 
menclature OXYGEN. 
the nitrous oxide, that containing the largest the nitric oxide. The 
acid compounds are similarly designated, as nitrous and nitric acid ; 
sulphurous and sulphuric acid ; and where there are intermediate com- 
pounds the term hypo is occasionally added to the acid next above it in 
point of oxidizement. Thus, hyposulphuric acid signifies an acid com- 
pound intermediate between the sulphurous and sulphuric acids ; hy- 
pophosphorous acid, an acid containing less oxygen than the phospho- 
rous acid. 
The different combinations of the metals with oxygen, are perhaps 
best distinguished by prefixing to the word oxide the first syllable of 
the Greek ordinal numerals, as originally proposed by Dr. Thompson. 
Thus the protoxide of a metal will denote the compound containing a 
minimum of oxygen, or the first oxide which the metal is capable of 
forming; deutoxide will denote the second oxide of a metal, <$-c. ; and 
when a metal is combined with the largest possible quantity of oxygen, 
the compound, if not acid, may be called peroxide. The same rule 
applies to the chlorides and iodides. 
The acids terminating in ous produce compounds in which the ter- 
mination ite is used ; while those ending in ic form compounds in which 
the ending ate is used. Thus the combination of sulphurous acid and 
potassa, is a sulphite of potassa; that of sulphuric acid and potassa, a 
sulphate of potassa, #c. 
When the same acid combines with more than one oxide of the same 
metal, the first syllable of the Greek ordinal numeral is in that case 
applied to the acid ; thus, the protosulphate and persulphate of iron sig- 
nify the combinations of sulphuric acid w ith the protoxide and perox- 
ide of iron. The term oxysulphate is occasionally used to designate 
the latter compound, and in the same sense we speak of oxynitrates, 
oxyphosphates, <yc., but the former mode of designation is less equivo- 
cal. 
The compounds of the simple inflammable bodies described in 
Chapter IV., writh each other, and with those in Chapter V., are 
commonly designated by the termination uret, as sulphuret of phos- 
phorus, phosphuret of carbon, carburet of iron, 4*c. 
The terms hi sulphuret, bi sulphate, biphosphuret, bi phosphate, 4'C.. 
applied to compounds, imply that they contain twice the quantity of 
sulphur, sulphuric acid, phosphorus or phosphoric acid, existing in 
the respective sulphuret, sulphate, phosphuret, and phosphate. 
Section I. Of Oxygen. 
198. This elementary gaseous body may be obtained by heating to 
redness, in a glass retort, the salt called chlorate of potassa (546) 100 
grains ol which yield about 100 cubical inches; it may be collected 
over water in the hydro-pneumatic apparatus. It is also given off 
from black oxide of manganese, red oxide of lead, and nitre, when ex- 
posed to a red heat. 
199. Common glass, or earthen-ware retorts, are used in these, and 
a variety of other chemical operations ; or, where a red heat is re- APPARATUS FOR OASES. 
67 
quired, they may he made of wrought iron, either in the same form, 
or in that of a bottle, tube, or other convenient shape. 
200. The hydro-pneumatic apparatus consists of a japanned iron or 
copper vessel, of different shape and size according to the particular 
purposes for which it is intended, and containing a shelf perforated 
with holes through which the gas may pass into inverted vessels pro- 
perly placed for its reception. In this wood-cut, a is the hydro-pneu- 
matic trough ; b b, inverted glasses for the reception of gas ; c, a 
wrought iron tube placed in a pan of charcoal for the evolution of 
gases requiring a red heat; n, a retort heated by the spirit lamp e. ] 
Hydro-pneu- 
matic appara- 
tus. 
201. For experiments, in which larger vessels are employed for col- 
lecting or transferring gases, the annexed form of the apparatus is most 
convenient. GAS-HOLDER. 
202. Vessels of various forms are employed for receiving, retaining, 
and measuring, gases. Where it is intended to introduce different 
substances into the gas, they may be of the form represented in figure 
1, drawn into a neck with a glass-stopper at top, and open at bottom. 
Some of these should be graduated into cubic inches, and supplied with 
a stop-cock, as in figure 2. For measuring small quantities of gases, 
tubes are employed, some of which should be divided into 100 equal 
parts, others into tenths and hundredths of a cubical inch. Figures 
3, 4. 
203. Where large quantities of gases are required to be collected 
and preserved, we employ gasholders and gasometers. The annexed 
cut represents Mr. Pepys’s improved gasholder, made of japanned 
iron, or what is preferable, of cop- 
per. It consists of a body or reser- 
voir a, which may hold from two to 
six or eight gallons, b, is a cistern 
from which issue two tubes, supplied 
with stop-cocks, one entering the re- 
servoir at its upper part; the other 
continued as shown by the dotted 
lines to near the bottom, c, is a 
short tube issuing fro# the bottom 
of the reservoir, and capable of be- 
ing accurately closed by a screw. 
d, is a glass tube communicating at 
both ends with the body of the gas- 
holder. When it is intended to till 
this apparatus with gas, the tube c is 
closed, and the stopcocks, e /, are 
opened ; wrater is then poured into 
the cistern, which running down the 
long tube c, forces the air out through the shorter one/. The reser- 
voir being thus filled, the stop-cocks are closed, and the aperture c, 
is opened, into which the beak of the retort, or tube, whence the gas 
issues, is introduced, and bubbling up, displaces the water which runs 
out at the same opening. When it is seen in the tube d, that nearly 
the whole of the water is displaced, the aperture is closed, and the 
vessel is now filled w'ith gas, which may either be drawn off into re- 
ceivers, placed in the cistern b, by opening the two stop-cocks ef; or 
Gasholder of 
Mr. Pepys. by closing the stop-cock f, and opening g, it may be propelled into 
bladders, or transferred in any convenient way by an attached tube. 
A view and section of the gasometer are shown in the following 
sketches ; 
GASOMETER. 
It may be made of japanned iron or copper, a a, is the outer circu- 
lar vessel, or pail, to the sides of which the tubes, d e, (each fitted with 
a stop-cock externally) are soldered. The tube d penetrates at the 
bottom of the pail, and proceeds to the centre, where it joins the tube 
e, which enters the top of the pail and proceeds downwards ; and from 
the place of junction, the upright tube g rises through the middle of the 
pail a little above the level of its upper rim. The vessel b is a cylinder 
open only at the bottom, and of less diameter than the pail into which 
it is inverted, and can move up and down freely. This cylinder has a 
solid stem c, which passes through a hole in the cross bar of the frame 
fixed to the top of the pail; it serves to steady the cylinder, and to in- 
dicate the quantity of the enclosed gas : the weight of the cylinder is 
counterpoised in any convenient way. 
To use this gasometer, first let the cylinder fall to the bottom of the 
pail, and fill the latter with waiter ; then shut the cock e, and open d, 
and connect with it the tube which conveys the gas from the retort or 
other vessel ; or if more convenient, shut d, and convey the gas 
through e. The gas rises and gradually lifts up the cylinder, which 
must be properly balanced ; and w-hen sufficiently filled, the cock, by which it entered, must be closed. The gas may now be drawn off at 
either of the stop-cocks, by a tube passing into the water-trough, or it 
may be propelled through a blow-pipe, or otherwise employed. 
204. *Oxygen gas is insipid, colourless, and inodorous ; its specific 
gravity is 16 hydrogen being assumed = 1. 100 cubical inches at mean 
temperature and pressure jveigh 33.88 grains. 
205. It is a powerful supporter of respiration and combustion. A 
small animal, confined in oxygen gas, lives thrice as long as when confi- 
ned in the same hulk of common air. A lighted taper, or a burning 
piece of sulphur, or phosphorus, introduced into this gas, is very ra- 
pidly consumed, with intense ignition. 
( 206. The phenomena of combustion were referred by Stahl and his 
associates, to a peculiar principle which they called phlogiston ; it was 
supposed to exist in all combustibles, and combustion was said to de- 
pend upon its separation ; but this explanation was absurdly at variance 
with the well-known fact, that bodies during combustion increase in 
weight. 
After the discovery of oxygen gas, it was adopted by Lavoisier as the 
universal supporter of combustion. The basis of the gas was sup- 
posed to unite to the combustible, and the heat and light which it be- 
fore contained in the gaseous state, were said to be evolved in the form 
of flame. But in this case, several requisites are not fulfilled ; the 
light depends upon the combustible, and not upon the quantity of 
oxygen consumed ; and there are very numerous instances of combus- 
tion in which oxygen, instead of being solidified, becomes gaseous 
during the operation; and, lastly, in others, no oxygen whatever is 
present. Combustion, therefore, cannot be regarded as dependent 
upon any peculiar principle or form of matter, hut must be consider- 
ed as a general result of intense chemical action. It may be connec- 
ted with the electrical energies of bodies ; for all bodies which power- 
fully act upon each other, are in the opposite electrical states of posi- 
tive and negative ; and the evolution of heat and light may depend 
upon the annihilation of these opposite states, which happens when- 
ever they combine. 
CHLORINE. 
Properties of 
oxygen gas. 
Supports res- 
piration. 
Stahl’s idea oi 
combustion. 
Theory of La- 
voisier. 
Insufficient. 
Combustion 
may be con- 
nected with 
the electrical 
energies of bo- 
dies. 
Section II. Of Chlorine. 
207. To obtain this gas, a mixture of black oxide of manganese 
and muriatic acid may he heated over a lamp in a glass retort. It is 
* As the specific gravities and atoms of the simple gases seem to be equimultiples of each 
other and as Thomson for very fair reasons has assumed the atom of oxygen as unity as well 
as its specific gravity in his late excellent paper, (ann. Philos ; October, 1820), we will follow 
him in order also to point out this interesting connexion. The specific gravity of oxygen will 
therefore be supposed =1.0 it has also been established, that, the atoms of all bodies, as far 
as examination has gone, are individually equamultiplies of the atom of hydrogen—for the 
purpose therefore of commencing at a proper place, to exemplify this law, we shall here state 
the atom of hydrogen = 0.125 (that of oxygen being = 1), and refer to sect. 235 for the cal- 
culation.— CHLORINE. 
71 
soon copiously evolved, and may be conveniently collected over warm 
water ; it is absorbed by cold water, and cannot therefore be long re- 
fined over that fluid. 
It may also be procured from a mixture of 8 parts of common salt, 
3 of black oxide of manganese, 4 of water, and 5 of sulphuric acid. 
208. Chlorine was discovered by Sclieele in 1774; it was called 
by him dephlogisticated muriatic acid. The term oxymuriatic acid 
was afterwards applied to it by the French chemists. 
209. Chlorine is a permanently elastic gaseous fluid ; it has a pun- 
gent and disagreeable smell, and is highly injurious when respired, 
even largely diluted with atmospheric air. Its colour is greenish yel- 
low. 
210. When dry, it suffers no change by exposure to the most in- 
tense cold, but in its ordinary state it contains aqueous vapour, which, 
at a temperature of 32°, is deposited in the form of a white crystal- 
line compound, which effervesces, and is again taken up by the gas, 
upon the application of heat. 
211. Chlorine is not altered by exposure to very high temperatures. 
By means of the following apparatus, Sir H. Davy exposed it to the 
continued action of charcoal intensely ignited by Voltaic electricity, 
without the smallest change in its properties. 
I Method of ob- 
taining chlo- 
rine. 
1 Time of dis- 
j covery syno • 
* noins. 
Characterise 
5 tics. 
* Unaltered in 
i high tempera* 
tares. 
) 
A glass globe of about four inches’ diameter, has at 
its upper part a sliding wire passing air-tight through 
a groundcollar, to the lower end of which is attach- 
ed a piece of well-burned charcoal : at the bottom 
is a stop-cock supporting a brass pincers, in which is 
another pointed piece of charcoal; the globe is ex- 
hausted upon the air-pump, filled with chlorine, and 
the stop-cock and sliding wire attached to the extre- 
mities of the Voltaic apparatus ; the charcoal points 
are then brought into contact by pushing down the 
upper wire, and they are thus retained as long as ne- 
cessary in intense ignitipn. 
*212. The specific gravity of chlorine, compared with hydrogen, is 
as 36 to 1 ; 100 cubic inches weigh 76.25 grains. 
213. At the temperature of 60°, water dissolves two volumes of 
chlorine. The solution is of a pale yellow colour, has an astringent 
nauseous taste, and destroys vegetable colours : hence its use in bleach- 
ing ; though the gas itself, when perfectly free from moisture, has 
scarcely any action upon them, 
214. When a burning taper is immersed in ajar of chlorine, the 
brilliancy of the flame is much impaired, it becomes red, throws off 
much charcoal, and is soon extinguished. 
Many bodies such as phosphorus and several of the metals, are 
spontaneously ignited by chlorine, and burn in it with much brilliancy. 
In these cases binary compounds result, some of which, like those of 
Specific gravi- 
ty- 
Solution in wa- 
ter, its use ia 
bleaching. 
Union witfa 
combustibles. 
* Sp. gr. of chlorine 2.25 or just fifths of 1 (the standard oxygen.) OXIDE, OP CHLOKINE. 
oxygen, are possessed of acid properties : others are not acid : and 
such compounds with oxygen being called oxides, those which chlorine 
forms may be termed chlorides. 
215. Chlorine was once regarded as composed of oxygen and muri- 
atic acid ; a fallacy arising from the presence of water, and which will 
be rendered more intelligible under the head Muriatic Acid. 
216. Chlorine and oxygen unite in three proportions, forming an ox- 
ide and two acids. 
217. Oxide of Chlorine, or Euchlorine, so called by its discoverer, 
Sir H. Davy {Phil. Trans. 1815,) from its very deep colour, may he 
obtained as follows : Upon 10 or 12 grains of chlorate of potassa, drop 
a small quantity of sulphuric acid, and stir the mixture with a platinum 
knife, having so adjusted the relative quantities of salt and acid that 
they may form together a yellow powder. Put this into a very small 
retort or bent tube, and by means of a water-bath, apply a tempera- 
ture of 150°. Oxide of chlorine will pass off, and may be collected 
over quicksilver in smalljars or tubes. 
218. Those gases which are absorbed by water, may, in most instan- 
ces, be collected over mercury. The best form of the Mercurio pneu- 
matic apparatus, is that contrived by Mr. Newman, {Quarterly Journal, 
Vol. i. p. 185.) It is a trough of cast-iron, supported by brass or iron 
legs, and having a small gasometer at one end. It is placed in a ja- 
panned iron-tray to collect the scattered mercury, as shown in the 
wood-cut. 
Formerly con- 
sidered as 
compound. 
Union of chlo- 
rine with oxy- 
gen. 
Mercurial ap- 
paratus for 
collecting ga 
ses. IODINE. 
219. Oxide of chlorine has an odour somewhat resembling that of 
chlorine, but much less irritating and disagreeable. Its taste is as-, 
tringent, and not at all acid. It dissolves in water, forming a lemon-1 
yellow solution. 
220. When oxide of chlorine is gently heated, it is decomposed 
with explosion and expansion : two volumes are enlarged into three, i 
of which two consist of oxygen, and one of chlorine ; it is therefore; 
composed (of 36 parts by weight of chlorine, combined with 32 of< 
oxygen)*. 
221. Chloric acid. In the substance which has been thus called by < 
its discoverer M. Gay-Lussac (Annales de Chirnie, tom xci. p. 108,)' 
thef (relative proportions of chlorine to oxygen are to each other as 
36. to 40.) But it is a compound which cannot exist, independent of 
water or some base, and, therefore, may be compared to the sulphuric 
and some other acids, afterwards to be described. 
Chloric acid may be prepared by passing a current of chlorine 
through a mixture of oxide of silver and water. Chloride of silver is 
produced, which is insoluble, and may be separated by filtration. 
The excess of chlorine, which the filtered liquor contains, is separable 
by heat, and the chloric acid dissolved in water remains. It is a sour, 
colourless liquid, producing peculiar compounds, afterwards to he de- 
scribed. It forms no precipitate in any metallic solution. The com- 
pounds may be called chlorates. The most remarkable of them have 
been long known under the name of Oxymuriates. 
222. Perchloric or oxychloric acid, is procured by distilling oxychlo- 
rate of potassa (547) with its own weight of sulphuric acid. It con- 
sists of (36. chlorine + 56. oxygen.) It does not exist independent 
of water, or a base, and has been but imperfectly examined. 
The proper terms for the above acids of chlorine would be Chlorous 
and Chloric acids, the former producing Chlorites and the latter Chlo- 
rates. 
Properties of 
oxide ol chlo- 
rine. 
When heated 
is decomposed 
with explosion 
and expansion 
composition. 
Composition of 
chloric acid. 
Preparation. 
Properties 
Preparation 
and composi- 
tionofperfthlo' 
ric acid. 
Section III. Of Iodine. 
223. Iodine is procured by the following process : Lixiviate pow- 
dered kelp with cold water. Evaporate the lixivium till a pellicle 
forms, and set aside to crystallize. Evaporate the mother liquor to 
dryness, and pour upon the mass half its weight of sulphuric acid. 
Apply a gentle heat to this mixture in the flask a of the alembic shown 
in the annexed figure, of which b is the head or capital, having a tube 
Process for ob- 
taining Iodine. 
* The gas, originally called Euchlorine by Sir H. Davy, appears to be a mixture of chlo- 
rine with the compound above described, and not a definite compound of two volumes of 
chlorine and one volume of oxygen. Should it, however, upon more accurate inquiry, prove 
a definite combination, it might be termed chlorous oxide, and the above compound would 
then be chloric oxide. 
t We have before remarked that the sp. gr. of chlorine (oxygen being 1) is =2.25, if we 
also take the atom of oxygen = 1, then to find the atom of chlorine we have only to double 
the specific gravity, viz. 2.25 X 2 = 4.5, the same as deduced above, from the proportional 
weights of constituents. Moreover the atom of hydrogen being already stated, = 0.125 the 
atom of chlorine is evidently 36 times as great or = 4.5, i. e. the atoms of these 2 gases are 
as their specific gravity. (Sec. 212.) IODIC ACID. 
issuing from it, and descending into the receiver c. Fumes of a violet 
colour arise and condense in the form of opaque crystals, having a me- 
tallic lustre, which are to be washed out of the head of the alembic 
with a small quantity of water, and quickly dried upon bibulous paper. 
Iodine may likewise be obtained from soap-makers’ black ash by a 
similar process; instead of evaporating the mother liquor to dryness, 
the quantity of iodine is sometimes greater when it is merely concen- 
trated, mixed with excess of sulphuric acid, boiled, and filtered : the 
liquid is then mixed with its weight of powdered black oxide of man- 
ganese, and heated in an alembic, or flask with a tube attached to its 
neck, when the iodine sublimes as before. 
This body was discovered in 1812, by M. Courtois, of Paris. Vau- 
quelin (Annales de Chimie, tom. xc.,) Gay-Lussac (ib. xc.,) and Davy 
[Phil. Trans. 1814,) have fully investigated its properties. 
Iodine has a bluish black colour ; its lustre is metallic. It is a 
nonconductor of electricity. It is soft and friable. *Its specific gravity 
=* 4.946. It produces a yellow stain upon the skin. Its smell resem- 
bles that of diluted chlorine ; its taste is acrid. It is extremely vola- 
tile, and, at a temperature between 60° and 80°, produces a violet 
vapour. At 120° or 130° it rises more rapidly. At 220° it fuses, and 
produces copious violet-coloured fumes, which condense in brilliant 
plates, and acute octoedrons. Like chlorine and oxygen, it is electro- 
negative ; and therefore attracted by the positive surface of the Voltaic 
pile. It renders vegetable colours yellow. It is very sparingly solu- 
ble in water, that liquid not holding more than its weight in solu- 
tion. The colour of the solution is yellow. It is much more soluble 
in spirit of wine, and in ether. 
224. Iodine combines with oxygen and with chlorine, and gives rise 
to two acid compounds which have been called Iodic, or Oxiodic, and 
Chloriodic acid. 
Iodic acid (Davy, Phil. Trans. 1815.) This compound of oxygen 
and iodine cannot be obtained directly, for those bodies exert no mu- 
tual action. It is procured by acting upon oxide of chlorine by iodine. 
Vroperties. 
Combination 
with oxygen 
gas. 
Iodic acid. 
* The specific gravity of Iodine vapour is to that of Hydrogen, as 125 : 1 and this X by the 
atom of hydrogen (0,125) gives the atom of iodine thus 125 X 0,125 = 15.625 atom Iodine. HYDROGEN. 
For this purpose the iodine may be introduced into a small flask, and 
the oxide of chlorine disengaged upon it, from a proper mixture of 
chlorate of potassa and sulphuric acid with the precautions above point- 
ed out (217,) or 100 grains of chlorate of potassa may be introduced, 
into a small retort, with 400 grains of liquid muriatic acid of the sp. gr. 1.1 
1.105 : annex to the retort a small globular receiver, having a bent tube 
issuing from it, and passing to the bottom of a small flask, containing 
about 50 grains of iodine ; carefully apply the heat ot a lamp to the 
retort, by which oxide of chlorine will be disengaged, and which will 
be decomposed and absorbed by the iodine. A compound is then 
formed, which consists of chloriodic and oxiodic acids. The former is 
separable by a gentle heat, the latter remains as a white, semitranspa-, 
rent, sour, and inodorous body, very soluble in water. It consists of 
125 iodine, 40 oxygen.)* 
225. Chloriodic acid is easily obtained by the direct action of chlo- < 
rine upon iodine. They unite and form crystals of a deep orange1 
colour, deliquescent, and easily fusible and soluble. The solution is 
sour. This compound contains (125 iodine, 36 chlorine.—Davy,1 
Phil. Trans. 1814. 
It appears probable from the experiments of M. Gay-Lussac, that 
another chloride of iodine exists, in which 2 proportionals of iodine 
are united to 1 of chlorine; but these compounds have not yet been 
examined with sufficient precision, to enable us to speak certainly 
upon their composition. 
Method of pro- 
curing iodio a- 
cid. 
Composition 
Chloriodic St- 
cid. 
Composition, 
CHAPTER IV. 
226. The bodies belonging to this class are electro-positive, and 
consequently, when separated from their combinations with the sub- 
stances described in the last chapter, by Voltaic electricity, they are 
attracted by the negative surface. With very few exceptions, they 
combine with the three supporters of combustion, already described, 
and of these compounds, one or more are acids. They are six in 
number: 
OF SIMPLE ACIDIFIABLE AND INFLAMMABLE SUBSTANCES. 
Electro-posi- 
tive. 
1. Hydrogen. 
2. Nitrogen. 
3. Sulphur. 
4. Phosphorus!. 
5. Carbon. 
6. Boron. 
Section I. Hydrogen. 
227, Hydrogen was first duly examined by Mr. Cavendish {Phil. 
* The specific gravity of iodine vapour, as deduced from hydriodic acid, (oxygen being 1) 
is == 7.8125, near by and its atom is just double or 15.625, (the atom also, of oxygen being 1) 
—again 0.125 (atom hydrogen) X 125 = 15.625 (atom Iodine.) 76 
Mode of pro- 
curing hydro- 
gen. 
ftYDROGEtf. 
Trans. Vol. lvi.) It may be obtained by the 
action of iron or zinc upon dilute sulphuric 
acid. Some pieces of iron-wire, or of zinc, 
may be introduced into the flask a, and co- 
vered with sulphuric acid diluted with six 
times its bulk of water. The gas escapes 
the bent tube b, which is inserted by 
grinding into the neck of the flask, and maj 
be collected in the hydro-pneumatic ap- 
paratus. 
Hydrogen is an aeriform fluid, not absorbable by water. It has no 
taste, a slightly disagreeable smell, and may be respired for a short 
time, though it is instantly fatal to small animals. It is the lightest 
body known ; and we therefore conveniently assume it as unity in 
speaking of the specific gravity of gases, as well as in referring to the 
proportions in which bodies combine. 100 cubic inches weigh at 
mean temperature and pressure 2.118 grains. Its specific gravity is 
0.0694, when common air is taken as 1.00, and 0.0625 when oxygen is 
= 1.00*. 
228. Hydrogen is inflammable, and extinguishes flame. When 
pure, it burns quietly with a lambent blue flame at the surface in con- 
tact with air; but, if mixed with thrice its volume of air, it burns ra- 
pidly, and with detonation. In making this experiment, a strong 
phial, capable of holding about 6 ounces of water, may be employed ; 
or the inflammable air-pistol, which admits of the mixture being fired 
by the electric spark. 
This instrument consists of a cylinder of brass, about three-fourths 
of an inch diameter, and six inches long, in the form of a small can- 
non or pistol-barrel, properly mounted, and having a wire, a, passing 
through a tube of ivory, b, and not quite touching the interior of the 
Character and 
Properties 
Weight. 
Inflamable air 
pistol. 
cylinder, at the part usually occupied by the touch-hole ; an electric 
spark communicated to this wire inflames the mixture of hydrogen and 
atmospheric air in its interior. It may be charged by previously fil- 
ling it with dry sand, and emptying it out into a phial of hydrogen, 
which rises into the gun sufficiently mixed with air ; the muzzle may 
be secured by a cork, which is expelled with much violence and a loud 
report, upon the inflammation of the gas. 
229. The electrical air-gun, may be also charged, by holding it for 
a moment over the open jet of the following instrument always taking 
care that there is a due admixture of atmospheric air, otherwise the 
electric spark will not inflame it. 
* We have seen that the specific gravity of hydrogen is 0.0625 when that of oxygen is taken 
= 1.00 now 0,0625 is just 16 times as small as 1,00 for 0.0625 X 16— 1, again to find the 
atom of hydrogen (he atom of oxygen being a pound —1, we have only to double the specific 
gravity 0.0625 i. e. 0.0625 X 2 = 0.125 atom hydrogen. (See. 236.) HYDROGEN. 
a is a funnel shaped vessel, fitting by a, 
ground-joint into the three-necked bottle 
b ; to the stopper c is annexed a brass 
wire, with a cylinder of zinc screwed 
upon its lower end ; is a tube furnished 
with a stopcock and jet-pipe ; the capaci- 
ty of the vessel a should be nearly equi- 
valent to that of b, and may contain 3 or 4 
pints. To charge this apparatus with hy- 
drogen, b is three fourths filled with water, 
and the stopper c being removed, a quan- 
tity of sulphuric acid, previously diluted 
with its bulk of water, is poured in by a 
long funnel, so that it may remain at the 
bottom of the water which now fills the vessel. The stopper c, with 
its appended piece of zinc, is then put in, and the generated hydrogen 
forces the dilute acid into a, where its pressure serves to propel the 
gas through d whenever the stop-cock is opened; the acid, at the 
same time descending, produces a fresh portion of hydrogen by again 
acting upon the zinc. This instrument is useful where small quanti- 
ties of hydrogen are required for burning, charging air-guns, and 
other purposes. 
230. If 2 volumes of hydrogen and 1 of oxygen be burned in the 
phial or air gun, the explosion is extremely violent. 
231. A current of hydrogen may be inflamed when 
issuing from a small aperture, and if a tube of 18 or 20 
inches in length be held over the flame, a peculiar mu- 
sical tone is produced. This effect is not peculiar to 
hydrogen, but is produced by a variety of other flames 
(Faraday, Journal of Science and the Arts, Vol. v.) and 
is referable to the succession of explosions produced by 
the combustion of the gas in the tube. 
232. The tendency which gaseous fluids have to be- 
come completely mixed under all circumstances, and as 
it were to penetrate each other, is well illustrated where 
hydrogen is employed. Thus, if two small phials, the 
one containing oxygen and the other hydrogen, be con- 
nected perpendicularly by a long glass tube, of small bore, 
it will be found, that although the hydrogen be upper- 
most, and much lighter than the oxygen, it will, in the 
course of a few hours, have perfectly mixed with the 
oxygen, and the gases will be found in equal proportions 
in both phials. Mr. Dalton has shown that gases, unlike 
other fluids, do not remain upon each other without ad- 
mixture.—Manchester Memoirs, Vol. i. New Series. 
233. Hydrogen, in consequence of its extreme light- 
nesses employed for filling air-balloons, and is elegantly 
applied to the purpose of obtaining instantaneous light in 
Volta’s inflammable air-lamp. 
231. The flame of hydrogen is occasionally employed for exciting in- 
tense heat; and it lias been found, when mixed with oxygen and burn- 
ed as the mixture issues from a small jet, to excite a temperature nearly 
equal to that of the arc of flame in the Voltaic circuit. A blow-pipe upon 
this construction was first made by Mr. Newman, at the suggestion of Mr. 
Musical tone* 
during the 
combustion of 
hydrogen. 
Gases have % 
powerful ten- 
dency to mix 
together. 
Use of hydro- 
gen as a blow- 
pipe. Brooks, and afterwards improved, as to its safety, by Professor Gum- 
ming, of Cambridge.—Journal of Science and the Arts, i. 65 and ii. 380. 
235. Hydrogen and oxygen.—When two volumes of hydrogen gas 
are mixed with one volume of oxygen gas, and the mixture inflamed in 
a proper apparatus by the electric spark, the gases totally disappear, 
and the interior of the vessel is covered with drops of pure water, 
equal in weight to that of the gases consumed. 
If pure water be exposed to the action of Voltaic electricity, it is 
resolved into two volumes of hydrogen, disengaged at the negative pole, 
and one volume of oxygen, disengaged at the positive pole ; so that 
water is thus proved by synthesis, and by analysis, to consist of two 
volumes of hydrogen, combined with one volume of oxygen. The 
specific gravity of hydrogen compared with oxygen, is as 1 to 16, there- 
fore the component parts of water bv weight are. 
WATER. 
Union with 
exygen gas. 
Composition 
of water. 
1 Hydrogen. 
8 Oxygen. 
9 Representative number of water. 
Hydrogen. 
Oxygen. 
8. 
Water 
or thus, 
9 
1. 
bo that 100 parts of water consist of 
88.89 Oxygen. 
11.11 
100,00 
236. The experiments illustrating the composition of water, may 
he divided into synthetic and analytic. Among these the following 
may be selected : 
i. Burn a current of hydrogen under the funnel a, represented in 
the following wood-cut; by uniting with the oxygen of the atmosphere 
Apparatus for 
Shewing the 
formation of 
water. it will produce aqueous vapour, which passing into the glass cylinder, 
i, will condense in drops. 
ii. The annexed woodcut represents an apparatus for showing the 
COMPOSITION OF WATER. 
production of water by burning a current of hydrogen in an atmos* Burnswith ox- 
gen gas and 
forms water. 
phere of oxygen, a is a glass cylinder, which after having been ex- 
hausted upon an air-pump, is filled with pure oxygen, b is a receiver 
of hydrogen immersed in the vessel of water c, by which the gas is 
compressed, so as to be urged through the capillary opening f, when 
the stop-cocks n d are open, e is a platinum wire by which the gas 
may be inflamed by an electric spark. It burns with the production 
of intense heat, and water is soon collected in drops upon the interior 
of the cylinder. 
iii. If two measures of pure hydrogen be mixed 
with one of pure oxygen, and detonated in the gra- 
duated glass tube a, standing over water, by an elec- 
tric spark passed through the platinum wires b b, 
the gases will entirely disappear. If there be any 
excess of either of the gases, the portion in excess 
will remain unconsumed. 
iv. the same experiment may be thus varied, a is 
very strong and thick glass vessel provided with 
a glass stop-cock e and with a ground stopper firmly 
secured by the wire c, through which the platinum 
wires d d pass. The vessel a being exhausted of 
air, is placed upon the bell-glass b, in the pneumatic 
trough, containing a mixture of pure oxygen and hy- 
drogen in the above mentioned proportions (235). 
Upon opening the stop-cock, e, a quantity of the 
mixed gases passes into a, where, after having care- 
fully closed the stop-cock, it may be inflamed by an electric spark 
passed through the platinum wires. At the instant of the detonation a 
The mixture 
explodes. 
vivid flame pervades the upper vessel, and it becomes lined with mois- ANALYSIS OF WATER. 
81 
lure. If the stop-cock be again opened a fresh portion of the mixed 
gases enters, and may be inflamed as before. 
237. Water may be decomposed or resolved into its elements by a, 
variety of processes, the most important of which are the following : 
i. a is a glass retort, into which is introduced a given weight of 
water ; b b a small furnace through which passes the earthen tube c c, 
which terminates in the spiral pewter tube d d, immersed in water. 
A given weight of pure iron wire, coiled up, is introduced into the tube 
c, and the whole made red hot ; the water in a is then made to boil, 
and the vapour, on coming into contact with the red-hot iron, is in 
part decomposed ; the oxygen is retained by the iron, and the hydro- 
gen escaping through the tube/, may be collected as usual. Any de- 
composed portion of water is condensed in the worm-pipe d, and drops 
into the vessel e. After this experiment the iron will be found to 
have increased in weight; and if attention be paid to the quantity of 
water which has collected in e, and to the weight of the hydrogen gas 
evolved, it will be found that the weight gained by the iron, added to 
that of the hydrogen, will be equal to the weight of the water which 
has disappeared. Lavoisier concluded, from an experiment thus 
conducted, that water consisted of 85 per cent, by weight of oxygen, and 
15 by weight of hydrogen ; that is, that for every 15 grains of hydro- 
gen evolved, 85 grains of oxygen were condensed by the iron. 
Analysis of 
water by ivou 
ii. Decomposition by Voltaic electricity (137) best illustrates the 
composition of water, since it exhibits both the oxygen and hydrogen 
in the gaseous form. The woodcut overleaf represents a section of 
an apparatus for this purpose. It is a glass vessel containing water, 
having two wires of platinum, ct a, passing through its bottom . over 
these are inverted the tubes b b, also filled with water. The wires 
are rendered positive and negative by connexion with a moderately- 
powerful Voltaic apparatus. Oxygen is evolved at the positive wire, 
and hydrogen at the negative wire, which gases rise into the tubes, and 
it is seen that one volume of oxygen, o, and two volumes of hydrogen, 
h, are the constant results. If these gases be mixed and detonated, 
pure water is again formed. 
By Voltaic 
electricity. PROPERTIES OP WATER, 
238. Water, in its ordinary state, such as spring and river mater, is 
always so far contaminated with foreign substances as to be unfit for 
many chemical purposes, and frequently, as will be more fully shown 
hereafter, even for domestic use. Rain-water is much more pure, but 
it always contains a portion of carbonic acid and of the elements of at- 
mospheric air, besides appreciable traces of vegetable or animal mat- 
ter ; to the latter it owes its property of becoming putrid when kept. 
The distinction of water into hard and soft has reference to its less or 
greater purity. The impurities of water are separated by distillation, 
which process is usually conducted upon the large scale in a copper 
boiler, a, placed either in a portable furnace, or set in brickwork, ac- 
cording to its dimensions, to which is annexed a head, b, of the same 
material, or of pewter connected with the pewter worm c, which is 
immersed in the worm-tub, or refrigerator, d, its lower end passing out 
at e. The water in this vessel must always be retained of a low tem- 
perature to effect the condensation of the vapour in the spiral tube. 
Heterogene- 
ous contents. water. 
Distilled water, as commonly prepared, always affords minute traces 
of foreign matter, especially when subjected to Voltaic decomposition, 
and can only be considered as perfectly pure when re-distilled at a 
low temperature in silver vessels. 
239. Pure water is transparent, and without either colour, taste, orr 
smell. In consequence of the facility of obtaining it pure, it is assum- s 
ed as a standard to which the relative weight of all other bodies may s 
he compared, its specific gravity being called = 1.000, and hence the1- 
importance of estimating its weight with precision. At the tempera- 
ture of 40° it is at its maximum of density, and at that temperature an 
English cubic foot weighs 437102.4946 grains (Thomson’s System, 
Vol. ii. p. 12.) or 999.0914161 ounces avoirdupois, and a cubic inch 
252.953 grains. 
240. At the temperature of 32° water congeals into ice, which, if 
slowly formed, produces needles crossing each other at angles of 60° 
and 120®. The specific gravity of ice is 0.94. Exposed to the air, 
ice loses considerably in weight by evaporation. 
241. If water be exposed to heat in open vessels it boils, oris con- 
verted into steam, at 212®, the barometer being at 30 inches ; but thej 
boiling point of water varies considerably with the pressure (83.) 
The specific gravity of air being considered as = 1 ; that of steam is 
0.6235. At mean pressure, and at the temperature of 212°, the bulk 
of steam is 1700 times greater than that of water. 
242. Water is susceptible of compression, as was originally shown 
by Canton, and more lately by Mr. Perkins, who has estimated, in an 
ingenious series of experiments, the rate of its compression (Phil. 
Trans. 1820.) If submitted to very sudden compression, water be- 
comes luminous, as has been shown by M. Desaignes.—Thenard, 
Traite de Chimie, i. 432. 
243. Water enters into combination with a variety of substances, 
and is retained with various degrees of force : where it contributes to 
the regular form and transparency of crystallized bodies, it is termed 
water of crystallization (12.) In other cases the compounds which 
water forms with substances are called hydrates, as with many of the 
metallic oxides (520) ; in both cases it may be considered as one of 
the constituents of the bodies, for it exists in them in a definite pro- 
portion. 
244. Water, which has been exposed to the atmosphere, always 
contains a portion of air, as may be proved by boiling it, or by expos- 
ing it under the exhausted receiver of the air-pump. To separate 
the air, the water must be boiled for about two hours. It absorbs oxy- 
gen gas in preference to atmospheric air or nitrogen, and when the 
air is expelled by boiling, the last portions contain more oxygen than 
those first given off.—Humboldt and Gay-Lussac, Journal de Physi- 
que, 1805. 
245. M. Thenard has shown that water may be united to a conside- 
rable excess of oxygen by means of peroxide of barium. (Quarterly 
Journal, Vol. viii. p. 114.) The specific gravity of oxygenated water 
is about 1.45. It acts as a caustic upon the skin ; detonates violently 
when dropped upon dry oxide of silver, or upon most of the metals 
finely divided. This singular compound may be termed peroxide of 
hydrogen: its properties, and the process for obtaining it, which is 
Complex and circuitous, have been fully detailed by its discoverer, and 
Properties 
Standard of 
specific gravi- 
ty- 
Boiling point. 
' Compressible 
i 
Unites to an 
f excess of oxy- 
.gen- WATER. 
will be adverted to under the article Peroxide of Barium, Vol. ii.. 
Section 5. Par. 630. 
246. The following table exhibits the quantity of different gases 
which water is capable of absorbing at mean temperature and pressure, 
the water being previously deprived of all aeriform matter by long 
boiling. 
GASES. 
100 Volumes of Water 
absorb 
AUTHORITY. 
Oxygen 
3.7 volumes 
Dalton. 
Chlorine 
200 
Oxide of Chlorine 
800 
Hydrogen 
1.56 
Henry. 
Muriatic acid 
50000. average 
Hydriodic acid 
Nitrogen 
1.56 
Henry. 
Nitrous oxide 
100 
Ditto. 
Nitric oxide 
5 
Nitrous acid 
Ammonia 
67000 average 
Sulphurous acid 
3300 
Thomson. 
Sulphuretted hydrogen 
100 
Dalton. . 
Hydroguret of phosphorus 
2.14 
Henry. 
Bi-hydroguret of phosphorus .... 
12 
Davy. 
Carbonic oxide 
2 average 
Carbonic acid 
100 
Dalton. 
Carburetted hydrogen 
12.5 
Dalton. 
Cyanogen 
450 
Fluoboric acid 
70000 
John Davy. 
Fluosilicic acid 
35000 
Saussure. 
247. As hydrogen is the lightest known substance, it is assumed in 
this work as unity, in reference to the representative numbers of other 
bodies. The principle of numeric representation, or of equivalent or 
proportional numbers, has already been adverted to (50), and the fol- 
lowing will be the representative numbers of the bodies described in 
the foregoing chapter, the number for oxygen being deduced from the 
composition of water (235), and of chlorine and iodine from the muri- 
atic (248) and hydriodic acids (259). 
Undecompouiided 
Proportional 
Substances. 
numbers. 
Hydi’ogen 
°xygen 
8 
Chlorine 
Iodine MURIATIC ACID. 
85 
Compounds. 
Component 
Parts. 
Representative 
Number. 
Water 
1 proportional of hydrogen 
1 ditto oxygen 
1 
8 
9. 
Oxide of 
chlorine 
4 proportionals of oxygen 
1 ditto chlorine 
32 
36 
68. 
Chloric acid 
\ 5 proportionals of oxygen 
► 1 ditto chlorine 
40 
36 
76. 
Perchloric 
acid 
7 proportionals of oxygen 
1 ditto chlorine 
56 j 
36 I 
92. 
Oxiodic acid 
5 proportionals of oxygen 
1 ditto iodine 
40 \ 
125 < 
165. 
Chloriodic 
acid 
1 proportional of chlorine 
1 ditto iodine 
36 
125 
161. 
248. Hydrogen and Chlorine.—When equal volumes of these gases 
are mixed and exposed to light, they combine, and produce a sour com- 
pound commonly called muriatic acid gas ; or, in conformity to more 
modern nomenclature, hydrochloric acid gas. If the above mixture be 
exposed to the direct solar rays, a detonation ensues, as was first remark- 
ed by M. M. Gay-Lussac and Thenard. (Recherches Physico-Chymi- 
ques, ii. 129.) It also detonates when exposed to the light of the Vol- 
taic discharge, showing a curious analogy between electric and solar 
light; for ordinary artificial light does not accelerate the combination. 
Brande, Phil. Trans. 1820. 
The best mode of showing the composition of muriatic acid, is to in- 
troduce into a small but strong glass vessel a mixture of the two gases, 
and to inflame them by the electric spark ; no change of volume ensues, 
and muriatic gas results. The apparatus shown at page 334, may be 
used for this purpose. 
249. Muriatic acid may be decomposed by the action of several of the 
metals. Potassium, for instance, absorbs the chlorine, and the hydro- 
gen is evolved ; muriatic acid gas thus affords half its volume of hydro- 
gen. As the specific gravity of hydrogen to chlorine is as one to 36.0, 
muriatic acid will consist of 1 hydrogen -f- 36.0 chlorine, and its repre- 
sentative number will be 37.0. 
Muriatic acid, 
Analysis of 
muriatic or hy- 
dro-chlorine 
acid. 
Hydrogen. 
Chlorine. 
Muriatic Acid. 
1 
36.0 
37.0 
250. Muriatic acid may be readily procured by acting upon com- 
mon salt by sulphuric acid ; the evolved gas must be received over mer- 
cury. It was tiz’st obtained pure bv I)r. Priestley, but its composition woulfe’s apparatus. 
was discovered by Scheele, and has since been most ably investigated 
by Davy. 
251. Muriatic acid gas extinguishes flame. Its specific gravity, com- 
pared with hydrogen, is = 18.5 ; 100 cubic inches = 39.162 grains.* 
252. Muriatic acid gas is greedily absorbed by water, which takes 
up 480 times its bulk, and has its specific gravity increased from 1 to 
1.210. 
253. For saturating water with gases which are easily soluble in 
that fluid, we generally employ Woulfe's apparatus, one form of which 
is shown in the annexed cut. a, is a tubulated retort in which the 
materials, producing the gas or vapour, are contained; b, a receiver 
communicating by a bent tube with the three-necked bottle c, which is 
connected also by a tube with d. These bottles are about half filled 
with water, or any other fluid intended to be saturated with the gas; 
when that in c has become saturated, it passes into d, and afterwards 
through the tube e, which may be placed under the water, or mercury, 
in the pneumatic trough. In case absorption should take place in the 
vessels a or b, the pressure of the external air might force the water 
from d into c, and from c into the balloon b. This is prevented by the 
safety tubes f f, which dipping not more than half an inch under the 
surface of the water, allow a little air to enter, so as to compensate for 
the absorption. The different joints may be secured either by grind- 
ing, or by well-cut corks rendered tight by a mixture of drying oil and 
pipe-clay. 
Properties. 
Absorbed by 
water. 
254. When muriatic acid is thus dissolved in water, it forms the li- 
quid muriatic acid or spirit of salt, and may easily be procured by dis- 
tilling a mixture of dilute sulphuric acid and common salt, as directed in 
the London Pharmacopoeia. The most economical proportions are 32 
parts of salt, and 22 of sulphuric acid, diluted with one third its weight 
of water. The retort containing these ingredients may be luted on to 
a receiver, containing twice the quantity of water used in diluting the 
sulphuric acid, and the distillation carried on in a sand-bath. 
255. When this liquid acid is pure it is perfectly colourless, but it 
generally has a yellow hue arising from a little iron. When heated, 
the gaseous acid is evolved. 
Mew #btain- 
ei. 
* 'W hen the specific gravity of oxygen =1, that of muriatic acid gas will be 1.156 ; now to 
find the atom of muriatic acid, we have only to multiply its specific gravity by 4, i e. 1,156 
X 4=4.625 the atom of muriatic acid, (when that of oxy gen is taken=l), again the atom of 
muriatic acid is 37 times as great as that of hydrogen, for 0.125 X 37=4.625. HYDfflODIC ACID. 
256. The following Table shows the quantity of real acid contained 
in 100 parts of liquid acid of different specific gravities.—Davy’s Ele- 
ments, p. 253. 
Fable showing the Quantity of real Acid in Liquid Muriatic Acid of different Specific Gravi- 
ties. (Temperature 45° Fahr. Barometer 30.) 
Specific 
Gravity. 
100 G rains contain of 
Muriatic Acid Gas. 
Specific 
Gravity. 
100 Grains contain of 
Muriatic Acid Gas. 
1.21 
42.43 
1.10 
20 20 
1.20 
40 80 
1.09 
18.18 
1.19 
38.38 
1.08 
16.16 
1.18 
36.36 
1.07 
14.14 
1.17 
34 34 
1.06 
12.12 
1.16 
32.32 
1.05 
10.10 
1.15 
30.30 
1.04 
8.08 
1.14 
28.28 
1.03 
6.06 
1 13 
26.26 
1.02 
4.04 
1.12 
24.24 
1.01 
2.02 
1.11 
22.30 
257. Hydrogen and Iodine exert a slow action under ordinary cir- 
cumstances ; but when iodine is presented to nascent hydrogen, they; 
readily unite, and produce a gaseous acid, the hydriodic acid. It is 
prepared by the action of moist iodine upon phosphorus, and must be 
received over mercury ; which, however, soon acts upon and decom- 
poses it, so that it should be transferred as speedily as possible into an 
exhausted vessel. In procuring it, it is convenient to use a small re- 
tort or bent tube, into the bulb of which is introduced the iodine, and 
a small stick of phosphorus placed in the neck above it, which can be 
shaken down upon the iodine when the beak of the tube or retort is 
placed under the inverted jar; a quantity of the gas is instantly and 
violently generated, and a further portion is obtained on applying the 
flame of a spirit lamp. 
258. Hydriodic acid is colourless, very sour, and smells like muri- 
atic acid*. Its specific gravity to hydrogen is as 63.00 to 1. 100 
cubic inches = 133.4 grains. 
259. Hydriodic gas is rapidly absorbed by water. The solution, ex- 
posed to a temperature below 260°, becomes concentrated by loss of 
water; at about 260° it boils, and may be distilled. The specific 
Hydriodic 
acid. 
* These conclusions are obtained from the fact, that, hydriodic acid is composed of equal 
volumes of hydrogen and iodine vapour. The specific gravity of hydriodic acid is 3.9375 
(or being “1), now four times this =15.75 the atom of this acid—again 15.75 is just 126 
times 0,125 the atom of hvdrogen, (that of oxygen being =1). NITROGEN. 
gravity of the strongest liquid acid is 1.7. It becomes dark coloured 
when kept, in consequence of a partial decomposition, and it readily 
dissolves iodine, becoming of a deep brown colour. 
The liquid hydriodic acid is best prepared by passing sulphuretted 
hydrogen through a mixture of iodine and water ; sulphur is deposit- 
ed, and on heating and filtering the liquor, a pure solution of hydriodic 
acid is obtained, which may be concentrated by evaporation. 
260. That hydriodic acid gas consists of equal volumes of hydrogen 
and vapour of iodine is shown by the action of mercury, which by ab- 
sorbing the iodine, evolves half a volume of hydrogen from one of the 
gas. 
It is instantly decomposed by chlorine, which produces muriatic 
acid and the blue vapour of iodine is rendered evident. These gases 
often take fire on mixture. 
It consists of... . 
. . . . 1.56 
hydrogen, 
0.248 (nearly 2 atoms) 
Hydriodic acid . . 
98.44 
100.00 
iodine, 
15.625 (1 atom) 
It is to be noted that Thomson in his system of chemistry gives the 
composition of this acid from the same data, 
Iodine 
8.6804 15.625(1 atom) 
Hydrogen 
0.0694 0.125(1 atom) 
261. This was first recognised as a distinct aeriform fluid, by Dr. 
Rutherford in 1772. (Thesis, De aere Mephitico.) It may be obtain- 
ed by heating phosphorus in a confined portion of dry atmospheric air, 
which consists of nitrogen and oxygen ; the phosphorus absorbs the 
latter, and the former gas remains. After repeated washing, it may be 
considered as pure. It may also be obtained by the action of moist 
sulphuret of iron upon atmospheric air. 
262. 100 cubic inches of nitrogen weigh 29.625 grains ; so that its 
specific gravity, compared with hydrogen, is as 14* to 1. It is tasteless, 
inodorous, and insoluble in water. It does not support combustion and 
is fatal to animals ; hence was called azote. It is not inflammable ; but 
when its compounds are submitted to Voltaic decomposition, it is attract- 
ed by the negative pole. 
263. Nitrogen and Oxygen.—These bodies unite in four proportions, 
and form the compounds called, 
Section II. Nitrogen. 
How obtain- 
ed. 
Properties. 
1. Nitrous oxide. 
2. Nitric oxide. 
3. Nitrous acid. 
4. Nitric acid. 
* When the specific gravity of oxygen is taken as the standard, or —1, that of nitrogen 
will be 0.875, or 14. of 11 again when the atom of oxygen is made 1, or the standard then 
twice the specific gravity of nitrogen will be its relative atom, thus, 0875X2=1.750 atom of 
nitrogen. JSITROUS OXIDE. 
264. Protoxide of Nitrogen, or Nitrous Oxide, may be obtained by 
heating in a glass retort over an Argand lamp, the salt called nitrate 
of ammonia, to a temperature of about 420°. The gas which passes 
off may be collected over warm water, and is nitrous oxide.* 100 cubic 
inches weigh 46.574 grains ; its specific gravity, therefore, to hydrogen 
is as 22 to 1. 
The taste of this gas is sweet, and its smell peculiar, but agreeable. 
It is easily absorbed by water, which takes up about its own bulk., 
and evolves it unchanged when heated. 
Its singular effects, resembling intoxication, when respired, were 
first ascertained by Sir H. Davy. (Researches Chemical and Philoso- 
phical, chiefly concerning Nitrous Oxide. London, 1800.) The ex- 
periment of breathing this gas, however, cannot be made with impu- 
nity, especially by those who are liable to a determination of blood to 
the head. 
265. Nitrous oxide supports combustion, and a taper introduced into 
it has its flame much augmented and surrounded by a purplish halo. 
Phosphorus and sulphur, when introduced in a state of vivid ignition 
into this gas, are capable of decomposing it, and burn with the same 
appearance nearly as in oxygen ; but, if when put into the gas, they are 
merely burning dimly, they then do not decompose it and are extin- 
guished, so that they may be melted in the gas, or even touched with a 
red hot wire without inflaming. Charcoal, and many of the metals; 
also decompose nitrous oxide at high temperatures. 
266. At a red heat this gas is decomposed and converted into nitron 
gen and nitric oxide, undergoing at the same time an increase of bulk. 
For experiments of this kind the following simple apparatus maybe 
used: It consists of two bladders, one of which is filled with the gas. 
and the other empty attached to the extremities of a porcelain tube 
which traverses the body of a furnace. The bladders are supplied 
with stop-cocks, and the gas is squeezed from one to the other when 
the tube is red hot. 
Nitrons oxide. 
267. The best analysis of this gas is effected by detonation with hy- 
drogen ; one volume of nitrous oxide requires one volume of hydrogen. 
This mixture fired by the electric spark, produces water, and one vo- 
lume of nitrogen remains. Now, as one volume of hydrogen takes half 
a volume of oxygen to form water, nitrous oxide must consist of two 
volumes of nitrogen and one volume of oxygen; these three volumes 
being so condensed in consequence of chemical union, as only to fill the 
Analysis of ni- 
trous oxide. 
* Protox of nitrogen, when oxygen is the standard has its specific gravity=1.375; this 
mult iplied by 2 gives 2.75 for the atom of nitrogen, when oxygen is also the atomic; standard— 
now 2.75 is just 22 times 0.125 (the atom of hydrogen, for the same standard.; 90 
NITRIC OXIDE. 
space of two volumes. The specific gravity of nitrogen compared with 
oxygen, is as 14 to 16 ; nitrous oxide, therefore, consists of 
14 Nitrogen 
8 Oxygen 
Number for nitrous oxide, = 22 
or, 
Nitrogen 
Oxygen 
Nitrous 
Oxide 
14 
8 
22 
268. Nitric oxide, deutoxide of nitrogen, or nitrous gas, is usually 
obtained by presenting certain substances to nitric acid, which abstract 
a portion of its oxygen, leaving the remaining elements in such pro- 
portions as to constitute the gas in question ; for this purpose some 
copper filings maybe put into a gas bottle (227) with nitric acid, dilu- 
ted with thrice its bulk of water ; an action ensues red fumes are pro- 
duced, and there is a copious evolution of the gas, which may be col- 
lected and preserved over water. The first portions should be rejec- 
ted as containing nitrogen and nitrous acid gas. Nitric oxide is pre- 
sently recognised by the red fumes wdiich it produces when brought 
into the contact of air. , 
* Its specific gravity to hydrogen is as 15 to 1. 100 cubic inches 
weigh 31.755 grains. When it has been washed with w ater it is not 
acid, as may be proved by the colour of litmus remaining unchanged 
by it. It extinguishes most burning bodies, but phosphorus readily 
burns in it, if introduced in intense ignition. 
269. It is not altered by a red heat, nor does it detonate when mix- 
ed with hydrogen, and subjected to the electric spark ; but it may be 
decomposed by the action of some of the metals at high temperatures, 
which absorb its oxygen. One volume of nitric oxide is thus resolv- 
ed into equal volumes of oxygen and nitrogen. If, therefore, we 
call nitrous oxide a compound of 1 proportional of nitrogen + 1 oxy- 
gen, then nitric oxide may be considered as consisting of 1 nitrogen-f- 
2 oxygen, or by weight, 14 nitrogen +16 oxygen, and its symbol will 
stand thus: 
Nitrogen 
Oxygen 
8 
Nitric Oxide 
14 
8 
30 
270. A piece of glowing charcoal plunged into nitric oxide gas is 
presently extinguished, but if it be passed through a porcelain tube 
containing red-hot charcoal, nitrogen and carbonic acid and oxide are 
produced. 
* \Vhen the specific gravity of oxygen =»1, the deutox. nitrogen =*0.9375—this multiplied 
by 4 gives 3.75 for its atom, (atom of oxygen being = 1)—further 3.75 is just 30 times, 125 
(the atom of hydrogen.) NITROUS ACID GAS. 
271. Nitric Oxide and Chlorine, when both are perfectly dry, 
exert no mutual action, but the presence of water causes an immediate 
change ; it is decomposed, and, furnishing oxygen to the nitric oxide, 
and hydrogen to the chlorine, nitrous acid and muriatic acid gases are 
generated. It was the presence of water which misled those, who 
thought that the red fumes produced by mixing nitric oxide and 
chlorine not carefully dried, resulted from the existence of oxygen in 
chlorine. 
272. Gay-Lussac has concluded from his experiments that there 
exists a compound of nitrogen and oxygen intermediate between nitric 
oxide and nitrous acid, which he has termed per-nitrous acid, but to 
which the term hyponitrous acid is more applicable. He considers it 
as a compound of 1 proportional of nitrogen, and 3 of oxygen ; but 
the existence of such a compound can scarcely be considered as ac- 
curately demonstrated. 
273. Nitrous Acid Gas.—When nitric oxide is presented to oxygen, 
the two gases combine, and a new gaseous compound of a deep orange 
colour results. This compound is not easily examined, because it is 
absorbed both by quicksilver and water, so that we are obliged to re- 
sort to exhausted glass vessels for its production. When we thus mix 
two volumes of nitric oxide with one volume of oxygen, the gases be- 
come condensed to about half their original volume, and form nitrous 
acid gas. 
This gas supports the combustion of the taper, of phosphorus, and 
of charcoal, but extinguishes sulphur. It is readily absorbed by water 
forming a green sour liquid. Its specific gravity to hydrogen is as 23 
to 1, and 100 cubic inches weigh 48.69 grains.* 
274. It is obvious that this nitrous acid gas must consist of 14 nitro- 
gen + 32 oxygen, and therefore, its number is 46 ; for nitric oxide is 
composed of equal volumes of nitrogen and oxygen, and one additional 
volume of oxygen, or two proportionals by weight are added to form 
nitrous acid. 
Nitrogen 
Oxygen 
8 
14 
8 
Nitrous 
Acid 
3 
8 
46 
8 
275. If the mixture of nitric oxide and oxygen be made over water, 
in the above proportions, and if the gases be perfectly pure, complete 
* Specific gravity of oxygen being =1; that of nitrous acid gas will be 2.875, this multi- 
plied by 2 will give 5.75 for the atom when that of oxygen =1, also, 5,75 is just 46 times 
6,125 (the atom of hydrogen.) absorption takes place ; but if either the oxygen or nitric oxide con- 
tain uncombined nitrogen it will remain unabsorbed. 
276. Nitric Acid.—The fourth compound of nitrogen with oxygen 
is the nitric acid ; the nature of which was first demonstrated by Mr. 
Cavendish in 1785. (Phil. Trans.) It is usually obtained by the distilla- 
tion of purified nitre with sulphuric acid, of which materials different 
proportions are employed. The nitric acid of commerce, which is ge- 
nerally red and fuming in consequence of the presence of nitric oxide, 
is procured by the distillation of two parts of nitre with one of sul- 
phuric acid ; these proportions afford about one part of orange-co- 
loured nitric acid of the specific gravity of 1.48. Upon the large scale 
112 lbs. of nitre, and 56 of sulphuric acid yield from 50 to 52 lbs. of 
nitric acid. Some manufacturers employ three parts of nitre and two 
of sulphuric acid, and the London Pharmacopeia directs equal weights, 
by which a nearly colourless nitric acid is afforded. 
It will appear by referring to the article Sulphuric Acid, that it con- 
tains in its liquid state one proportional of dry acid, and one of water ; 
whereas liquid nitric acid contains one proportional of dry acid, and 
two of water ; hence the requisite excess x>f sulphuric acid, where co- 
lourless and perfect nitric acid is to be obtained ; hence too the red 
colour of the acid of commerce in consequence of the smaller quanti- 
ty of sulphuric acid generally used by the manufacturer. This will 
be more apparent by reference to the article Bi-sulphate of Potassa. 
The distillation of nitric acid may be conducted upon the small scale 
in a tubulated glass retort a, with a tubulated receiver b, passing into 
the bottle c. The requisite heat is obtained by the lamp d, and the 
whole apparatus supported by the brass stands with sliding rings e e. 
Nitric acid. 
f But the manufacturer who prepares nitric acid upon a large scale, 
generally employs distillatory vessels of stone-ware. The following 
wood-cut represents the arrangement of tbe distillatory apparatus, 
employed at Apothecaries’ Hall, for the production of common aqua- 
Preparation ef 
aitrous acid- NITRIC ACID. 
fortis; it consists of an iron pot, set in brick.work, over a fire-place ; 
an earthenware head is luted upon it, communicating with two receiv- 
ers of the same material, furnished with earthenware stop-cocks, the 
last of which has a tube of safety dipping into a basin of water. 
£77. The nitric acid of commerce, as obtained by the above pro- 
cesses, is always impure, and muriatic and sulphuric acids may usually 
be detected in it. The former may be separated by nitrate of silver, 
and the latter by a very dilute solution of nitraie of baryta. To ob- 
tain pure nitric acid, therefore, add to that of commerce a solution of 
nitrate of silver as long as it produces any white precipitate ; and 
when this has subsided, pour off the clear liquor, and add, in the 
same way, the nitrate of baryta ; then distil the acid, and it will pass 
over perfectly pure. For pharmaceutical purposes, the ordinary acid 
is generally sufficiently pure. If, however, pure nitre, and pure sul- 
phuric acid be employed in its production, and the latter not in excess, 
there is little apprehension of impurity in the resulting acid, 
The nitric acid is a colourless liquid, extremely sour and corrosive.. 
Its specific gravity is 1.42 ; it always contains water, which modifies 
its specific gravity. At 250° it boils and distils over without change.; 
At—10° it congeals. It absorbs water from the air, and its bulk is 
thus increased,While its specific gravity is diminished. It is usually 
coloured by nitrous acid gas, which it evolves when heated. 
278. Nitric acid in its dry state, that is, as it exists combined with 
metallic oxides in the salts called nitrates, may be regarded as com- 
posed of one proportional of nitrogen = 14, and 5 of oxygen = 40, 
and this will be the symbol representing its composition. 
Properties of 
nitric acid. 
Specific gra- 
vity. 94 
NITRIC ACID. 
Oxygen 
8. 
Nitrogen. 
14 
8. 
8. 
40 
8. 
8. 
Consequently, tlie representative number of dry nitric acid is 54.0. 
But in its liquid state it always contains water ; and when in this state 
its specific gravity is 1.5, it may be regarded as a compound of one 
proportional of dry acid and two of water, which may be numerically 
expressed thus: 
Acid. Water. 
54. -f* 17 = 74.0 liquid acid. 
279. The following Table drawn up by Dr. Ure, exhibits the quan- 
tity of real acid in the liquid acid of different densities :—Quarterly 
Journal, iv. 297. 
Quantity of 
real acid. 
Specific 
Gravity. 
Acid in 
100. 
! Specific 
| Gravity. 
Acid in 
100. 
Specific 
Gravity. 
Acid in 
100. 
1.5000 
79.700 
1.3783 
52 602 
1.1833 
25.504 
1.4980 
78.903 
1.3732 
51.805 
1.1770 
24.707 
1.4960 
78.106 
1.3681 
51.068 
1.1709 
23.910 
1.4940 
77.309 
1.3680 
50.211 
1.1648 
23.113 
1.4910 
76.512 
1.3579 
49.414 
1.1587 
22.316 
1.4880 
75.715 
1.3529 
48.617 
1.1526 
21.519 
1.4850 
74.918 
1.3477 
47.820 
1.1465 
20.722 
1.4820 
74.121 
1.3427 
47.023 
1.1403 
19.925 
1.4790 
73-324 
1.3376 
46.226 
1.1345 
19 128 
1.4760 
72.527 
1.3323 
45.429 
1.1286 
18.331 
1.4730 
71.730 
1.3270 
44.632 
1.1227 
17.534 
1.4700 
70.933 
1.3216 
43.835 
1.1168 
16.737 
1.4670 
70.136 
1.3163 
43.038 
1.1109 
15.940 
1.4640 
69.339 
1.3110 
42.241 
1.1051 
15.143 
1.4600 
68 542 
1.3056 
41.444 
1.0993 
14.346 
1.4570 
67.745 
1.3001 
40.647 
1.0935 
13.549 
1.4530 
66 948 
1.2947 
39.850 
1.0878 
12.752 
1.4500 
66.155 
1.2887 
39.053 
1.0821 
11.955 
1.4460 
65.354 
1.2826 
38.256 
1.0764 
11.158 
1.4424 
64.557 
1.2765 
37.459 
1.0708 
10.361 
1 4385 
63 760 
1.2705 
56.662 
1.0651 
9.564 
1.4346 
62.963 
1.2644 
35.865 
1.0595 
8.767 
1.4306 
62.166 
1.2583 
35.068 
1.0540 
7.970 
1.4269 
61.369 
1.2523 
34.271 
1.0485 
7.173 
1.4228 
60 572 
1.2462 
33.474 
1.0430 
6.376 
1.4189 
59.775 
1.2402 
32.677 
1.0375 
5.579 
1.4147 
58.978 
1.2841 
31.880 
1.0320 
4 782 
1.4107 
58.181 
1.2277 
31.083 
1.0267 
3.985 
1.4065 
57.384 
1.2212 
30.286 
1.0212 
3.188 
1.4023 
56.587 
1.2148 
29.489 
1.0159 
2.391 | 
1.3978 
55.790 
1.2084 
28.692 
1.0106 
1.594 1 
1.3945 
54.993 
1,2019 
27.895 
1.0053 
0.797 I 
1.3882 
54.196 
1.1958 
27.098 
1.3833 
53.399 
1.(895 
26.301 
1 CHLORIDE OF NITROGEN. 
280. Nitric acid may be decomposed by passing its vapour through a 
red hot porcelain tube ; oxygen is given off, nitrous acid gas is pro- 
duced, and a quantity of diluted acid passes over into the receiver, 
having escaped decomposition ; so that it is thus proved to consist of 
nitrous acid gas, oxygen and water. 
For experiments of this kind the form of apparatus, described for 
the decomposition of water by iron, may be employed (Sec. 237), 
omitting the condensing worm-pipe. 
The nature of nitric acid was first synthetically demonstrated by 
Mr. Cavendish, who passed electric sparks through a portion of at- 
mospheric air, or through a mixture of one part of nitrogen and two 
of oxygen, confined over mercury. After some time the mixture di- 
minished in bulk, and, on admitting a little water, an acid solution was 
obtained, which afforded chrystals of nitre when saturated with po- 
tassa. 
281. Nitro-muriatic Acid.—This term has been applied to the 
Aqua Regia of the alchemists. When nitric and muriatic acids are 
mixed, they become yellow, and acquire the power of readily dis- 
solving gold, which neither of the acids possessed separately. This 
mixture evolves chlorine, a partial decomposition of both acids having 
taken place, and water, chlorine, and nitrous acid gas, are thus pro- 
duced ; that is, the hydrogen of the muriatic acid abstracts oxygen 
from the nitric to form water : The result must be chlorine and ni- 
trous acid.—Daw, Journal of Science and the Arts, Vol. i. p. 67. 
282. Nitrogen and Chlorine.—Chloride of Nitrogen.—These gases 
do not unite directly, but the compound may be obtained by exposing 
a solution of nitrate or muriate of ammonia to the action of chlorine 
at a temperature of 60® or 70®. The gas is absorbed, and an oil-like 
fluid, heavier than water, is produced. It was discovered by M. Du- 
long, in 1812.—Annales de Chimie, Vol. lxxxv. 
The simplest mode of obtaining this compound, consists in filling i 
perfectly clean glass basin with a solution of about one part of sal 
ammoniac in twelve of water, and inverting into it a tall jar o 
chlorine. The saline solution is gradually absorbed and rises into the 
jar, a film forms upon its surface, and it acquires a deep-yellow co 
lour; at length small globules, looking like yellow oil, collect upor 
its surface, and successively fall into the basin beneath, whence the] 
are most conveniently removed by drawing them into a small and per 
fectly clean glass syringe, made of a glass tube drawn to a pointer 
orifice, and having a copper wire with a piece of clean tow wrapper 
round it for a piston ; in this way a globule may be drawn into tlu 
tube, and transferred to any other vessel. 
Composition 
of nitric acU. 
Its specific gravity is 1.G5 ; it is not congealed by cold. Its odour 
is irritating and peculiar; it very soon evaporates when exposed to 
air. This substance is dangerously explosive, and is decomposed with 
violent detonation by many combustibles, especially phosphorus, and 
fixed oils. CHLORIDE OP NITROGEN. 
In making these experiments, a small globule of the compound, 
about the size of a mustard-seed, should be cautiously transferred to 
a clean porcelain basin, half filled with water ; a very small piece of 
phosphorus, fixed to the end of a long stick, or a long rod with the 
extremity dipped in oil may be then brought into contact with the 
globule, which instantly explodes, dispersing the water, and breaking 
the basin. At 160° it distils without change, but at 212° explodes, and 
is decomposed. It was submitted to the action of 125 different sub- 
stances, by Messrs. Porret and Wilson, of which the following caused 
it to explode: 
Phosphorus. 
Phosphuret of lime. 
Caoutchouc. 
Myrrh. 
Palm-oil. 
Whale-oil. 
Linseed-oil. 
Olive-oil. 
Oil of turpentine. 
Naptha. 
Liquid ammonia. 
Phosphuretted hydrogen. 
Nitric oxide. 
The metals, resins, and sugar did not cause it to explode.—Nichol- 
son’s Journal, Vol. xxxiv. 
Alcohol quietly changes it into a white substance. Mercury absorbs 
the chlorine and evolves nitrogen. It yields, by decomposition, 1 
volume of nitrogen and 4 of chlorine ; and as the specific gravity of 
nitrogen to chlorine is as 14 to 36.0, so it maybe said to consist of 1 
N C 
proportional of nitrogen 4- 4 proportionals of chlorine, or 14 + 144, 
by weight, and its number will be 158. 
Composition 
of chloride of 
nitrogen. 
Nitrogen. 
Chlorine. 
14 
36. 
36 
144 
36 
36 AMMONIA. 
97 
In the state of vapour, it is probable that the five volumes of aeri- 
form matter which it affords by decomposition, are condensed into one, 
since its decomposition by mercury is not attended by any change of 
its volume. - 
283. Nitrogen and Iodine.—A compound of these bodies may be 
procured by pouring a solution of ammonia upon a very small quantity 
of iodine. Hydriodic acid is one product, and the other a brown pow- 
der, which detonates upon the slightest touch, and is resolved into ni- 
trogen and iodine. It may be collected by pouring off the liquid, and 
placing it, while moist, in small parcels upon bibulous paper, where it 
must be suffered to dry spontaneously. When it detonates, the purple 
fumes of iodine are perceptible. When left exposed to air it gradually 
evaporates. 
284. Nitrogen and Hydrogen—Ammonia ; or Volatile Alcali.—This 
gaseous compound may be obtained by heating a mixture of quicklime 
and muriate of ammonia. Two parts of dry quicklime and one of mu- 
riate of ammonia may be introduced into a small glass retort, and, upon 
the application of a gentle heat, the gas passes over. It must be col- 
lected over mercury. Tt is permanently elastic at common tempera- 
tures, extremely pungent and acrid, but when diluted by mixture with 
common air, agreeably stimulant. It converts most vegetable blues to 
green, and the yellows to red, properties which belong to the bodies 
called alcalis. Ammonia, therefore, has been termed volatile alcali. 
* Its specific gravity to hydrogen is as 8.5 to 1 ; 100 cubical inches 
•weighing 18 grains. It extinguishes flame, but forms an inflammable 
mixture with common air and with oxygen. 
285. Water, at the temperature of 50°, takes up 670 times its volume 
of ammonia ; its bulk is increased, and its specific gravity diminished : 
that of a saturated solution is 0.875, water being 1.000. The follow- 
ing Table shows the quantity of ammonia in solutions of different spe- 
cific gravities.-—Daw’s Chem. Phil. p. 268. 
Ammonia. 
Specific gra- 
vity. 
*00 Parts of Sp. Gr. Of Ammonia. 
100 Parts of Sp. Gr. Of Ammonia, 
t*8750 T 32.50 
8875 29.25 
9000 26.00 
9054* n , . 25.37 
9166 Contam 22.07 
9255 19.54 
9326 17.52 
9385 L 15.88 
9435 1 f 14.53 
9476 13.46 
9513 12.40 
9545 ~ . 11.56 
9573 Contam 10.82 
9597 10.17 
9619 9.60 
9692* J t 9.50 
The usual state in which ammonia is employed is in solution, both in 
chemistry and medicine. This solution bears the name of Liquor Am- 
monia in the London Pharmacopoeia. It may be obtained by passing 
the gas into water in a proper apparatus (253,) or by distilling over the 
water and gas together. 
The following process, recommended by Mr. R. Philips, answers 
well. On 9 ounces of well-burned lime pour half a pint of water, and 
when it has remained in a well-closed vessel for about an hour, add 12 
Preparation of 
liquor Ammo- 
nia. 
* When sp. gr. ox. =1, that of ammonia will be 0.53125; this multiplied by 4 will give 
the atom of ammonia =2125, and this atom is just 17 times the atom of hydrogen, (0.125.) 
f The three results marked by the asterisk, were gained by experiments, the other num- 
bers by calculation. 98 
AMMONIA. 
ounces of muriate of ammonia in powder and three pints and a half of 
boiling water ; when the mixture has cooled, pour otf the clear por- 
tion, and distil from a retort 20 fluid ounces. The specific gravity of 
this solution, which is sufficiently strong for most purposes, is 0.954— 
Remarks on London Pharmacopoeia, p. 34. 
The specific gravity of the officinal solution directed in the Pharma- 
copoeia, is 0.960. 
Liquid ammonia should be preserved in well-stopped glass bottles, 
since it loses ammonia and absorbs carbonic acid, when exposed to air. 
When heated to about 140°, ammonia is rapidly given off by it; when 
concentrated it requires to be cooled to — 40° before it congeals, and 
then it is apparently inodorous. 
If a piece of ice be introduced into ajar of ammonia standing over quick- 
silver, it melts with great rapidity, and liquid ammonia is produced. 
286. Dr. Henry (Phil. Trans. 1809,) first observed that a mixture 
of ammonia and oxygen gas might be fired by an electric Spark, and 
this property furnishes a means of analyzing the alcaline gas. Elec- 
tricity also decomposes ammoniacal gas. If a succession of electrical 
sparks be passed through a small portion of the gas confined in a pro- 
per tube over quicksilver, it will increase to about twice its original 
bulk, and lose its easy solubility in water. If the gas thus expanded be 
mixed with from one-third to one-half its bulk of oxygen, and an elec- 
tric spark passed through the mixture, an explosion takes place, at- 
tended by considerable diminution. Note the amount of the diminu- 
tion, divide it by 3, and multiply the product by 2. The result shows 
the quantity of hydrogen. Thus, suppose 10 measures of ammonia, 
expanded by electricity to 18, and that, after adding 8 measures of 
oxygen gas, we find the whole (= 26 measures,) reduced by firing to 
6 measures, the diminution will be 20. Then 20 -f- 3 —- 6.66 and 
6.66 X 2 = 13.32 measures of hydrogen gas from 10 of ammonia; 
and 18— 13.32 = 4.68 for the nitrogen gas contained in the product of 
electrization. Therefore, 10 measures of ammonia have been destroy- 
ed and expanded into 
13.32 measures of hydrogen gas, 
4.68 - - - - nitrogen gas. 
Henry’s Elements, 7th edit. Vol. i. p. 233. 
It appears probable that one volume of ammonia is resolved by 
electric decomposition into two volumes of a mixture of hydrogen and 
nitrogen, consisting of three volumes of hydrogen and one volume of 
nitrogen ; hence the following symbols will represent the composition 
and volume of ammonia : 
Analysis of 
ammonia. 
Nitrogen 
Hydrogen 
14 
1 
Hydrogen 
1 
= 17 
Ammonia. 
Hydrogen 
17 
1 MURIATE OF AMMONIA. 
99 
When ammonia and oxygen are detonated, the nitrogen is oxidized 
as well as the hydrogen ; hence, if excess of oxygen be used, the 
whole of the ammonia disappears, and nitrate of ammonia is formed. 
Ammonia is decomposed by passing it through a red-hot iron tube ; 
it suffers expansion, and is resolved into hydrogen and nitrogen gases, 
furnishing a singular instance of change of properties in consequence 
of chemical combination, a is a bladder filled with ammonia which 
may be passed through the iron tube b, placed in the furnace c; the 
gas is decomposed, and hydrogen and nitrogen may be collected over 
the water in d. 
Ammonia is also decomposed when passed over black oxide of man- 
ganese, heated red-hot in a porcelain tube ; the results are water and 
nitrous acid gas ; nitrate of ammonia is also often formed. 
287. Ammonia is produced synthetically during the decomposition 
of many animal substances ; it is also formed during the violent action 
of nitric acid upon some of the metals ; and by moistened iron-filings 
exposed to an atmosphere of nitrogen ; in these cases the nascent 
gases unite so as to form a portion of ammonia. 
288. Ammonia combines with the acids, and produces a class of 
salts which, with very few exceptions, are soluble in water, and which 
evolve the odour of ammonia when mixed with lime or with pure po- 
tassa. These salts are, for the most part, entirely dissipated, and, 
generally speaking, decomposed by. heat. 
289. Ammonia and Chloric Acid—Chlorate of Ammonia is formed 
by saturating chloric acid with carbonate of ammonia. It forms very 
soluble acicular crystals, of a sharp taste, which detonate when 
thrown upon hot coals. It probably consists of 1 proportional of each 
of its components, or 17 ammonia+ 76 chloric acid. 
290. Iodate of Ammonia forms small indeterminate crystals ; when 
heated they are decomposed into oxygen, nitrogen, water, and iodine. 
Their composition has not been ascertained. 
291. Ammonia and Chlorine.—When these gases are mixed, a par- 
tial decomposition of the former ensues. On mixing 15 parts of 
chlorine and 40 of ammonia, 5 parts of nitrogen are liberated, and 
muriate of ammonia is formed. If the gases be perfectly dry, con- 
siderable heat is evolved, and a flame is perceived to traverse the 
vessel in which the experiment is made. 
292. Ammonia and Muriatic Acid—Muriate of Ammonia—Sal Am- j 
moniac—This salt may be produced directly by mixing equal volumes ® 
of ammonia and muriatic acid, when an entire condensation ensues. 
The specific gravity of ammonia to muriatic acid is as 8.5 to 18.5 ; 
therefore, muriate of ammonia consists of 18.5 muriatic acid+ 8.5 
ammonia. 
Synthesis. 
Salts of aroitio- 
I nia. 
Muriate of am- 
monia. 100 
NITRATE Off AMMONIA. 
Ammonia 
Muriatic Acid. 
8.5 
18.5 
27. 
Muriate of ammonia was formerly imported from Egypt, where it 
Was obtained by burning the dung of camels ; it is now abundantly pre- 
pared on the Continent and in this country. Its preparation will be 
hereafter described. When obtained by evaporation from its solution 
in water, it forms octoedral, prismatic, and plumose crystals ; but, in 
commerce, it usually occurs, as procured by sublimation, in white 
cakes, hard, and somewhat elastic, and in this compact state it requires 
for solution 3.25 parts of water at 60°. When heated it sublimes 
without decomposition in the form of white vapour. Its specific 
gravity composed with water is = 1.45 (Dr. Watson.) 
Sal-ammoniac is used in the arts for a variety of purposes, especial- 
ly in certain metallurgic operations. It is used in tinning, to prevent 
the oxidation of the surface of copper ; and small quantities are con- 
sumed by dyers. Dissolved in nitric acid, it forms the aqua regia of 
commerce, used for dissolving gold, instead of a mixture of nitric and 
muriatic acids (281). 
293. Muriate of Ammonia occurs massive and crystallized, in 
the vicinity of volcanoes, and in the cracks and pores of lava near their 
craters. It has thus been found at Etna, and at Vesuvius, in the Solfa- 
terra near Naples, and in some of the Tuscan Lakes. An efflorescence 
of native sal-ammoniac is sometimes seen upon pit-coal. Its colour 
varies from the admixture of foreign matter, and it is frequently yel- 
low from the presence of sulphur. It is said that considerable quan- 
tities of native sal-ammoniac are also found in the country of Bucha- 
ria, where it occurs with sulphur in rocks of indurated clay. The 
ancients according to Pliny, called this salt ammoniac, because it was 
found near the temple of Jupiter Ammon, in Africa. 
294. Hydriodate of Ammonia.—In a former paragraph (283) the 
action of iodine on ammonia has been stated to produce a portion of hy- 
driodate of ammonia : this compound may be directly formed by mix- 
ing equal volumes of hydriodic and ammoniacal gases ; or by saturating 
liquid hydriodic acid by carbonate of ammonia ; it forms very soluble 
and deliquescent cubic crystals, volatile in close vessels without decom- 
position.—Gay-Lussac, Annales deChim. xci. 
295. Ammonia and Nitric Acid—Nitrate of Ammonia.—This salt may 
be procured by the direct union of ammonia with nitric acid ; or more 
easily, by saturating dilute nitric acid with carbonate of ammonia. It 
has been mentioned as the source of nitrous oxide, and when heated is 
entirely resolved into that gas and water. * It consists of one propor- 
tional of nitric acid = 54 -f- one proportional of ammonia =17, and 
therefore the representative number of nitrate of ammonia is 71. Or 
it may be considered as containing two proportionals of nitrogen, three 
of hydrogen, and five of oxygen, as the following symbols show : 
Native. 
Hydriodate of 
ammonia. 
Nitrate of am- 
monia. 
Specificgravi- 
fy. 
* Its specific gravity compared with water, is 1.5785. (Fourcroy). NITRATE OF AMMONIA. 
r 
Nitric Acid. 
Nitrate of Ammonia. 
Ammonia. 
54. 
17. 
Nitrogen 
Oxygen 
8. 
Nitrogen 
Hydrogen 
14 
14 
1 
8. 
8. 
1 
8. 
1 
8. 
Nitrous oxide consists of 1 proportional of nitrogen = 14-f l 0f 
oxygen = 8 ; hence the 2 proportionals of nitrogen in the salt (1 in the 
acid and 1 in the ammonia,) will require 2 of oxygen to produce nitrous 
oxide, and the remaining 3 of oxygen will unite to the 3 of hydrogen, 
and form water ; and accordingly nitrous oxide and water are the onlv 
possible results ; so that the elements after the decomposition of the 
salt, are arranged thus : 
Two proportionals of Nitrous Oxide. Three proportionals of Water. 
Nitrogen 
Oxygen 
8. 
Oxygen 
14 
Hydrogen 
1 
8. 
8. 
14 
1 
8. 
1 
Nitrate of ammonia has long been known, and was formerly called 
Nitrum flammans. It differs in form according to the manner in which 
its solution has been evaporated ; if at a temperature below 100°, its 
crystals are six-sided prisms terminated by six-sided pyramids ; if boil- 
ed down, its crystals are thin and fibrous : it is deliquescent, and solu- 
ble in twice its weight of water at 60°, and in its own weight at 212°. 
Its taste is acrid and bitter. It contains different proportions of water 
of crystallization ; according to Berzelius, the prismatic variety affords 
Proportions of 
water. 102 
ATMOSPHERIC AIR. 
11.232 per cent. (80 Annales de Chimie.) According to Davy, the 
fibrous variety contains 8.2 per cent.; and the compact, obtained by 
evaporating the solution till it concretes, 5.7 per cent, of water of crys- 
tallization.—Davy’s Researches, p. 71. 
294. Atmospheric Air.—The composition of atmospheric air lias 
been frequently alluded to in the preceding pages, and as the student 
is now acquainted with its essential component parts, namely, oxygen 
and nitrogen, it may be right to consider its properties more at length. 
The atmosphere is a thin, transparent, invisible, and elastic fluid, 
which surrounds our planet and reaches to a considerable height above 
its surface, probably about 40 miles. 
That air is a ponderous body, was first suspected by Galileo, who 
found that a copper ball, in which the air had been condensed, weigh- 
ed heavier than when the air was in its ordinary state of tension. 
The fact was afterwards demonstrated by Torricelli, whose attention 
was drawn to the subject by the attempt of a well-digger at Florence, 
to raise wrater by a sucking-pump to a height exceeding 33 feet. It 
was then found that the pressure of the atmosphere, and not nature’s 
abhorrence of a vacuum, was the cause of the ascent of the water in 
the pump-pipe, and that a column of about the height mentioned was 
sufficient to equipoise the atmosphere. 
In 1643, Torricelli filled a glass tube, three feet long and closed at 
one end, with quicksilver, and inverted it in a basin of the same fluid ; 
he found that the mercury fell about six inches, so that the atmosphere 
appeared capable of counterbalancing a column of mercury 30 inches 
in height. The empty space, in the upper part of the tube, has hence 
been called the Torricellian vacuum, and is the most perfect that can 
be formed. 
Paschal and Torricelli afterwards observed, that upon ascending a 
mountain, the quicksilver fell in the tube, because there was less air 
above to press upon the surface of the metal in the basin ; and thus a 
method of measuring the heights of mountains by the barometer, as the 
instrument is now called, was devised. Sir Henry Englefield has con- 
structed a barometer, expressly for these investigations, the mode of 
using which is described in the Journal of Science and the Arts, Vol. v. 
p. 229. 
The barometer indicates, by its rise and fall, a corresponding change 
in the density of the atmosphere. At the surface of the earth the mean 
density or pressure is considered equal to the support of a column of 
quicksilver 30 inches high. 
Atmospheric. 
air. 
At 1000 feet above 
Inches. 
the surface the column falls to 28.91 
2000 
27.86 
3000 
26.85 
4000 
25.87 
5000 
24.93 
1 Mile 
24.67 
2 ..... 
20.29 
3 
16.68 
4 
. . . 13.72 
5 
11.28 
10 
4.24 
15 
1.60 
20 AIR-tfUMP. 
103 
295. The general mechanical properties of the air are best illus- 
trated by the air-pump, the construction of which much resembles ] 
that of the common sucking-pump used for raising water, excepting 
that all the parts are more accurately and nicely made, the object be- 
ing to exhaust the air as completely and expeditiously as possible. 
The annexed sketch will give an idea of the operation of the common 
air-pump a b are cylinders, into which the sliding-pistons c d are ac- 
curately fitted, e is a tube issuing from the bell-glass placed upon a 
brass plate/, and entering the lower part of the cylinders at h h, where 
are valves opening upwards. In each piston is also a valve opening 
upwards at g g. The cylinder a represents the piston in the act of 
being drawn up. By elevating the piston c an attempt will be made 
to form a vacuum underneath it ; but a portion of the air in conse- 
quence of its elasticity, will pass out of the bell /, along the tube e, 
and elevating the valve h, will fill the space below the piston, the 
valve g being kept closed by the weight of the incumbent atmosphere. 
In the cylinder b the piston is represented in the act of depression, the 
valve h therefore is forced down upon the orifice, which it perfectly 
closes ; and the air, confined between it and the piston, now makes its 
escape by the piston-valve g, which is accordingly open, so that at 
every stroke of the pump a portion of air is withdrawn from the re- 
ceiver/. 
Mechanical 
properties of 
air. 
With this air-pump it is obviously impossible to obtain more than an 
imperfect vacuum in the receiver /, for the valves can only act by the 
elasticity of the remaining air ; and, accordingly, if a barometer be 
placed under the receiver, the mercury will never attain a level in 104 
the tube and basin, but will always indicate a degree of pressure, as is 
shown by the small syphon gauge at i; and if a tube 3 feet long have its 
upper end opening into the receiver, and its lower end plunged into a 
bason of mercury, the mercury will never rise so high as in the com- 
mon barometer, where the vacuum above it is perfect, but will indicate 
the. pressure of a remnant of air in the receiver. The syphon gauge, 
and the barometer as applied at k, are very useful appendages to the 
air-pump, as showing the degree of exhaustion, and its permanence. 
The operation of the pump in removing air, and the mechanical 
properties of the atmosphere, may be shown by a variety of experi- 
ments. Its pressure is illustrated by the force with which the bell-glass 
is pressed down upon the plate of the pump ; the absence of its buoy- 
ancy, by the descent of a guinea and a feather at the same time in the 
exhausted receiver ; and by the preponderance of the larger of two 
bodies which balance each other in the open air. The want of resis- 
tance in the exhausted receiver is also shown by the equal duration of 
the motion of two fly wheels, with their plates placed in different di- 
rections. 
296. The specific gravity of atmospheric air, at mean temperature 
and pressure, that is, the thermometer being at 60°, and the barom- 
eter at 30 inches, is usually considered as = 1. It is about 828.59 
times as light as its bulk of water, 100 cubical inches weighing 30.5 
grains. 
For ascertaining the specific gravity of gaseous bo- 
dies, a good air-pump is essentially requisite ; a light 
glass balloon or flask b; and a graduated air-jar a, 
each supplied with stopcocks, are also required. 
Dr. Henry, in his excellent Elements of Chemistry, 
(Vol. i. p. 126,) has given the following directions for 
proceeding to estimate the specific gravity of gases, 
which can scarcely be improved upon ; it only re- 
quires to be observed, that the gases should, in general, 
be retained and collected over mercury, and care- 
fully dried by exposing them to proper substances for 
absorbing the moisture which they hold in solution, 
and which would materially affect the accuracy of the 
result; or they should be taken saturated with mois- 
ture, and a deduction afterwards made for the weight 
of the vapour contained in a given bulk of the gas. 
Supposing the receiver a to be filled with any gas, the weight of 
which is to be ascertained, we screw the cock of the vessel b on the 
plate of an air-pump, and exhaust it as completely as possible. The 
weight of the exhausted, vessel is then very accurately taken, even to 
a small fraction of a grain ; and it is screwed upon the air-cock of the 
receiver a. On opening both cocks, the last of which should be turn- 
ed very gradually, the gas ascends from the vessel a ; and the quan- 
tity which enters into the flask, is known by the graduated scale on a. 
On weighing the vessel a second time, we ascertain how many grains 
have been admitted. If we have operated on common air, we shall 
find its weight to be at the rate of 30.5 grains to 100 cubical inches. 
The same quantity of oxygen gas will weigh 33.75 grains, and of car- 
bonic acid gas 4fi«57 grains. 
WEIGHT pF GASES, WEIGHT OF GASES. 
105 
In experiments of this kind it is necessary either to operate with 
the barometer at 30 inches, and the thermometer at 60° Fahrenheit, 
or to reduce the volume of gas employed to that pressure and tempera- 
ture, by rules which are given in the note*. Great care is to be ta- 
ken, also, not to warm any of the vessels by contact with the hands, 
from which they should be defended by a glove. On opening the com-, 
munication between the receiver and the exhausted vessel, if any 
water be lodged in the air-cock attached to the former, it will be forci- 
bly driven into the latter, and the experiment will be frustrated. This 
may be avoided by using great care in filling the receiver with water, 
before passing into it the gas under examination. 
* Rales for reducing the Volume of Gases to a mean Height of the Barometer, and mean 
Temperature. 
i. From the space occupied by any quantity of gas under an observed degree of pressure, 
to infer what its volume icould be under the mean height of the barometer, taking this at 30 
inches, as is now most usual. 
This is done bv the rule of proportion; for, as the mean height is to the observed height, 
so is the observed volume to the volume required. For example, if we wish to know what 
space would be filled, under a pressure of 30 inches of mercury, by a quantity of gas, which 
fills 100 inches, when the barometer is at 29 inches. 
30 : 29 : : 100 : 96.66. 
The 100 inches would, therefore, be reduced to 96.66. 
ii. To estimate what would be the volume of a portion of gas, if brought to the tempera- 
ture of 60° Fahrenheit. 
Divide the whole quantity of gas by 480; the quotient will show the amount of its ex- 
pansion or contraction by each degree of Fahrenheit’s thermometer. Multiply this by the 
number of degrees, which the gas exceeds, or falls below 60°. If the temperature of the 
gas be above 60°, subtract, or if below 60u, add, the product to the absolute quantity of gas; 
and the remainder in the first case, or sum in the second, will be the answer. Thus, to find 
what space 100 cubic inches of gas at 50° would occupy if raised to 60°, divide 100 by 480; 
the quotient 0.208 multiplied by 10 gives 2.08, which added to 100 gives 102.08, the answer 
required. If the temperature had been 70°, and we had wished to know the volume which 
the gas would have occupied at 60°, the same number 2.08 must have been subtracted from 
100, and 97.92 would have been the answer. 
iii. In some cases, it is necessary to make a double correction, or to bring the gas to a mean 
both of the barometer and thermometer. We must then first correct the temperature, and 
afterwards the pressure. Thus, to know what space 100 inches of gas at 70° Fahrenheit, 
and 29 inches barometer, would fill at 60° Fahrenheit and 30 inches barometer, we first re- 
duce the 100 inches, by the second process, to 97.92. Then by the first, 
30 : 29 : : 97.92 : 94.63. 
Or 100 inches thus corrected, would be only 94.63. 
iv. To ascertain what would be the absolute weight of a given volume of gas at a mean 
temperature, from the known weight of an equal volume at any other temperature; fiist, find 
by the second process what would be its bulk at a mean temperature; and then say, as the 
corrected bulk is to the actual weight, so is the observed bulk to the number requiied. Thus, 
if we have 100 cubic inches of gas weighing 50 grains at 50° Fahrenheit, if the temperature 
were raised to 60° they would expand to 102.08. And 
102.08 : 50 : : 100 : 49. 
Therefore 100 inches of the same gas at 60° would weigh 49 grains. 
v. To learn the absolute weight of a given volume of gas under a mean pressure, from 
its known weight under an observed pressure, say as the observed pressure is to the mean 
pressure, so is the observed weight to the corrected weight. For example, having 100 in- 
ches of gas which weigh 50 grains under a pressure of 29 inches, to know what 100 inches of 
the same tras would weigh, the barometer being 30 inches, 
29 : 30 : : 50 : 51.72. 
Then 100 inchesof the same gas, under 30 inches’ pressure, would weigh 51.72 grains. 
vi. In some cases it is necessary to combine the two last calculations. Thus, if 100 in- 
ches of <ras at 50° Fahrenheit, and under 29 inches’ pressure, weigh 50 grams, to find what 
would be the weight of 100 inches at 60° Fahrenheit, and under 30 inches of the barometer, 
first correct the temperature, which reduces the weight to 49 grains. Then, 
29 : 30 : : 49 : 50.7. 
100 inches, therefore, would weigh 50.7 grains^ 106 
WEIGHT OP GASES. 
The specific gravity of any gas compared with common air is readily- 
known, when we have once determined its absolute weight. Thus, 
if 100 cubic inches of air wreigh 30.5 grains, and the same quantity of 
oxygen gas weigh 33.88 grains, we say, 
30. 5 : 33.88 : : 1.000: 1.1111. 
The specific gravity of oxygen gas, compared with atmospheric air, 
will, therefore, be as 1.1111 to 1.000. 
We may determine, also, the specific gravity of gases more simply by 
weighing the flask, first when full of common air, and again when ex- 
hausted ; and afterwards by admitting into it as much of the gas under 
examination as it will receive, and weighing it a third time. Now as 
the loss between the first and second weighing is to the gain of weight 
on admitting the gas, so is common air to the gas whose specific gravity 
we are estimating. Supposing, for example, that by exhausting the 
flask it loses 30.19 grains, and that by admitting carbonic acid it gains 
46.57; then 
30.5 : 46.57 : : 1.000 : 1.527. 
The specific gravity of carbonic acid is therefore 1.527, air being taken 
at 1.000. And knowing its specific gravity, we can, without any far- 
ther experiment, determine the weight of 100 cubic inches of carbonic 
acid ; for, as the specific gravity of air is to that of carbonic acid, so is 
30.5 to the number required ; or 
1.000 : 1.527 : : 30 5 : 46.57. 
100 cubic inches, therefore, of carbonic acid will weigh 46.57 grains. 
Assuming atmospheric air at 30 inches barometrical pressure, and 
60° temperature = 1, the following Table exhibits a series of compa- 
rative specific gravities; the First column shows the results of experi- 
ments chiefly made at the Royal Institution : The Second contains the 
weight of 100 cubic inches, calculated from the preceding column : the 
Third, specific gravities upon other authorities ; and the Fourth con- 
tains some calculated results obtained by M. Gay-Lussac ; and others. WEIGHT OF GASES. 
107 
GAS. 
Specific 
100 
Other Authorities. 
OBSERVATIONS. 
Grav. 
Cub. In. 
Atmospheric air 
1.0000 
grs. 
30.20 
The average weight of 
100 cubic inches of atmos- 
Oxygen. . 
1.1175 
33.75 
1.10359 Biot and Arago 
pheric air, deduced from 
Chlorine 
2.4957 
75.37 
C 2.470 Gay-Lussac and The- 
( 2.500 Prost [nard 
twelve experiments made 
with great care and an ex- 
cellent balance, is 30.199 
Oxide of Chlorine 
2.3653 
71.43 
2.361 Thomson 
grains, at mean tempera- 
ture and pressure. Sir G. 
Iodine (vapour of) 
8.7723 
264.90 
8.678 Gay-Lussac 
Shuckburgh’s experiments 
give the weight of 100 cu- 
Hydrogen 
0.0745 
2.25 
0.07321 Biot and Arago 
bic inches =30.5, and the 
table given by Dr. Thom- 
Water (vapour of) 
0.6235 
18.80 
0.624 Gay-Lussac 
son (System iii. 25,) is 
founded on this datum. 
Muriatic acid 
1.2851 
38.80 
1.278 Biot and Gay-Lussac 
Hydriodic acid 
4.4234 
133.60 
4.375 Thomson 
Nitrogen 
0.9681 
29.25 
0.96913 Biot and Arago 
( 
1.52092. Upon the suppo- 
Nitrous oxide ....... 
1.5272 
46.12 
1.36293 Berthollet ) 
sition that its elements suf- 
fer a condensation equal to 
the volume of its oxygen. 
( 
The mean of equal vo- 
Nitric oxide ....... 
1.0428 
31.50 
1.0388 Berard 
lumes of oxygen and nitro- 
Nitrous acid 
2.1356 
64.50 
2.1099 Gay-Lussac 
•.59438. Supposing the 
Ammonia 
0.5960 
18.00 
0.5966 Biot and Arago 
condensation of elements 
— 0.5 of their entire vo- 
lume. 
Sulphurous acid ...... 
2.3350 
67.50 
2.2553 Gay-Lussac & The- 
[nard 
1.1912 Ditto 
Sulphuretted hydrogen . . . 
1.1920 
36.00 
Phosphuretted hydrogen . . . 
0.8940 
27.00 
0.9022 Thomson 
Hydrophosphoric gas .... 
0.9685 
29.25 
0.9716 Ditto 
C 
0.96782. Supposing 100 of 
Carbonic oxide 
0.9834 
29.70 
0.9569 Cruickshanks ✓ 
carbonic acid minus 50 
oxygen to produce 100 car- 
bonic oxide. 
Chlorocarbonic acid .... 
3.4791 
105.07 
3.472 Thomson 
Carbonic acid 
1.5421 
46.57 
1.5196 Biot and Arago 
Carburetted hydrogen (olefiant) 
0.9983 
30.15 
1.000 T. de Saussure 
1.8178 
54.90 
1.804 Gay-Lussac 
Chlorocyanic acid ..... 
2.1527 
65.13 
2.152 Thomson 
Hydrocyanic acid 
0.9461 
28.57 
0.9368 Ditto 
Sulphuret of Carbon (vapour of) 
2.670 Gay-Lussac 
Fluoboric gas....... 
2.400 
72.50 
2.3709 Thomson 
Fluosilicic gas 
Alcohol (vapour of) .... 
3.5740 
110.78 
1.500 Gay-Lussac 
Sulphuric ether (ditto) . . . 
2.396 Ditto 
Muriatic ether (ditto) .... 
2.219 Thenard 
Hydriodic ether (ditto) . . . 
5.475 Thomson 
Chloric ether (ditto) .... 
3.474 Ditto 
Oil of turpentine (ditto) . . . 
5.013 Ditto 
The chief numbers in this table were determined in the Royal Institution, the results therefore) cannot here be altered 
as they are of a peculiar nature, but elsewhere it has been done whenever no authority is given. 108 
EUDIOMETERS. 
297. Atmospheric air has already been stated to consist essentially 
of oxygen and nitrogen gases ; but whether it should be considered a 
mere mixture or a chemical compound seems a question not easily de- 
cided. 
There are various ways of learning the proportion which the oxy- 
gen bears to the nitrogen; and as the relative fitness of the air for 
breathing has sometimes been considered as depending upon the quan- 
tity of oxygen contained in a given volume, the instruments used in 
these experiments have been called eudiometers. 
298. From facts already stated it is obvious, that if atmospheric air, 
mixed with a certain quantity of hydrogen, be detonated by the elec- 
tric spark (236 iii.) the absorption will be proportionate to the quan- 
tity of oxygen present. 
When 100 measures of pure hydrogen are mixed with 100 of pure 
oxygen, the diminution of bulk after detonation will amount to 150 
parts, that is, one volume of oxygen requires for its saturation two of 
hydrogen. If we introduce into the graduated detonating tube (p. 80) 
300 measures of common air, and 200 of pure hydrogen, there will re- 
main, after detonation 305 measures ; so that 195 measures will have 
disappeared, of which one-third may be estimated as pure oxygen ; 
hence 300 parts of air have thus lost 65 of oxygen, or about 21 per cent. 
The general rule, therefore, for estimating the purity of air by hy- 
drogen gas may be stated as follows :—Add to 3 measures of the air 
under examination 2 measures of pure hydrogen ; detonate ; and, 
when the vessel has cooled, observe the absorption ; divide its amount 
by 3, and the quotient is the quantity of oxygen. 
Upon the same principle, detonation of mixtures of oxygen and hy- 
drogen is often resorted to, with a view of ascertaining the purity of 
those gases. Thus, suppose 100 measures of oxygen, and 300 of hy- 
drogen, to be reduced by detonation to 130, the whole diminution will 
be =270, which, divided by 3, gives 90 for the quantity of oxygen ; so 
that it contained 10 per cent, of some gas, not condensible by detona- 
tion with hydrogen. 
To ascertain the purity of hydrogen, it may he detonated with ex- 
cess of pure oxygen. Thus, if we add 100 of pure oxygen to 100 of 
hydrogen, and detonate, there will be a diminution equal to two-thirds, 
or 150 parts if the hydrogen be pure. If, however, we suppose 100 
of pure oxygen, mixed with 100 of hydrogen, to produce, after deto- 
nation, a residue of 80 measures ; the diminution will then have been 
only 120 measures, of which two-thirds, or 80 measures, are hydro- 
gen ; so that the inflammable gas will have contained 20 per cent, of 
some other gaseous body, not condensible by detonation with hydro- 
gen; 
This mode of ascertaining the purity of atmospheric air was first re- 
sorted to by Volta, and it is susceptible of great accuracy, since pure 
hydrogen and pure oxygen are easily procured. An improved deto- 
nating tube for these purposes has been described by M. Gay-LussAC, 
Annales de Chim. et Phys. IV. 188. 
300. Scheele, in his eudiometrical experiments, employed sulphuret 
of potassa, (556) the solution of which rapidly absorbs oxygen, as may 
be shown by agitating it with some atmospheric air in a graduated glass 
tube. In this experiment the nitrogen remains unaltered. 
Composition 
of atmospheric 
air. 
Eudiometer of 
Volta. 
Of Scheele. EUDIOMETERS. 
109 
i he best instruments tor these experi- 
ments are the eudiometric tubes of Dr. 
Hope (Nicholson’s Journal, Vol. iv.) 
and Dr. Henry (Elements, Vol. i. p. 
149) as represented in the marginal 
woodcuts. The former consists of a 
small bottle, holding about three ounces, 
into which the graduated glass tube a is 
carefully fitted by grinding. It also has 
a ground stopper at b. To use it, the 
phial is filled with the solution of the al- 
caline sulphuret, and the tube a, contain- 
ing the air to be examined, fitted into its 
place. After inverting and agitating the 
instrument, the stopper b may be opened under water, and the ab- 
sorption is shown by the rise of the fluid in the tube. For the glass 
bottle Dr. Henry substituted the elastic gum bottle b, in the neck oi 
which a short piece of glass tube is secured, into which the tube a is 
fitted by grinding. 
In the Philosophical Transactions for 1807, Mr. Pepys has describ- 
ed a modification of this Eudiometer, which may be often advanta- 
geously employed in delicate experiments, and by which an absorption 
of only TuVo Part °f gas under examination may be measured. 
301. YVhen nitric oxide gas and atmospheric air are mixed, there is 
a production of nitrous acid, in consequence of the union of oxygen 
with the oxide (273) ; and if the mixture be made over water, an ab 
sorption proportiohal to the quantity of nitrous acid formed ensues 
Upon this principle nitric oxide may be used in eudiometrical experi 
ments, and, if proper precautions be attended to, it furnishes tolera 
bly accurate results. Dr. Priestley and Mr. Cavendish (Phil. Trans 
1783,) availed themselves of this mode, and Mr. Dalton has offered 
some remarks upon its relative accuracy (Phil. Mag. Vol. xxviii.) 
The most certain results are obtained by adding to 100 parts of the at- 
mospheric air, previously introduced into a small beer glass, an equal 
volume of nitric oxide gas. The mixture may be gently agitated, and 
in two or three minutes, carefully decanted into a graduated tube, when 
it will be found that 84 measures have disappeared; of which one- 
fourth, or 21 measures, are oxygen. 
Sir H. Davy suggested the use of a solution of sulphate of iron, im- 
pregnated with nitric oxide gas, for the absorption of oxygen ; it may 
be employed in the same way as the alcaline sulphuret (300.) 
302. If a stick of phosphorus be confined in a portion of atmospher- 
ic air it will slowly absorb the oxygen present. The rapid combustion 
of the same substance may also be conveniently 
resorted to. For this purpose a small piece of 
phosphorus may be introduced into the bulb of 
the tube a, containing a given measure of the air 
to be examined, confined over mercury, which, 
to prevent loss by expansion, should be suffered 
to occupy about half the tube, or to stand at b. 
The phosphorus may then be inflamed in the 
tube ; and when the combustion is over, and the 
tube cold, the residuary air may be transferred 
for measurement. These eudiometrical methods 
were used bv Lavoisier, Berthollet, and Seguin 
Of Hope. 
Of Pepys. 
Of Priestley. 
Of Pavy, 
Of Lavois.fl?, 
&o. HYGROSCOPES AND HYGROMETERS.' 
(Annales de Chimie7tom ix. and xxxiv.) and are both susceptible of ac- 
curacy, and a loss of volume = 21 per cent, of the atmospheric air, will 
invariably be found to have occurred. 
303. By experiments thus conducted, it has been found that the 
composition of the atmosphere is extremely uniform in all parts of the 
world, and at all heights above its surface ; and that it consists of, 
By Measure. 
. . . . 21 
By Weight. 
23.3 
Nit.rogp.ri. . . 
. . . . 79 
76.7 
100 
100.0 
Though these are the essential component parts of atmospheric air, 
it contains other substances, which, however, maybe regarded as adven- 
titious, and the quantity of which is liable to vary : of these, carbonic 
acid and aqueous vapour are the most important and constant. The 
quantity of the former may usually be considered as amounting to less 
than 1 per cent. 
The presence of aqueous vapour in the atmosphere is shown in a 
variety of ways, but most easily by exposing to it certain deliquescent 
substances which liquefy and increase in weight, in consequence of its 
absorption ; and as the gases in general, unless artificially dried, also 
contain vapour of water, it is necessary, in delicate experiments, and 
in ascertaining their specific gravity, to take this ingredient into the 
account, or to separate it by proper means, such as exposure to very 
deliquescent substances, among which fused chloride of calcium (623) 
is especially useful. 
The quantity of water contained in air and gases is subject to varia- 
tion. From the experiments of Saussure and Dalton, it appears that 
100 cubic inches of atmospheric air at 57°, are capable of retaining 
0.35 grains of watery vapour ; in this state the air may be considered 
at its maximum of humidity : it would also appear that all the gases 
take up the same quantity of water when under similar circumstances, 
and that it consequently depends, not upon the density or composition, 
but upon the bulk of the gaseous fluid. 
We are indebted to Mr. Dalton for some valuable information re- 
specting the state in which water exists in air; from which it may be 
concluded that it is in the state of vapour, forming an independent at- 
mosphere, mixed, but not combined with, or dissolved in the air. 
304. Hygroscopes and Hygrometers are instruments which show the 
presence of water in the air, its variation in quantity, and its actual 
quantity existing in a given bulk of air at any given time. Saussure 
employs a human hair, which, by its dilitations and contractions in 
moisture and dryness, is made to turn an index ; Deluc used a thin strip 
of whalebone in the same way ; Wilson employs a rat’s bladder, which 
is filled with mercury, and tied on to a large thermometer tube, and by 
its dilatation and contraction causes the mercury to fall and rise in the 
tube, and thus to indicate changes in the moisture of the air. Mr. Daniell 
has constructed an hygrometer, which shows the constituent tempera- 
ture of the moisture in the atmosphere, by its precipitation upon a cold 
surface ; comparing this with the temperature of the atmosphere, the 
difference furnishes a datum for calculating the quantity of vapour in 
a given quantity of air, and affords indications usefully applicable to 
Carbonic acid 
in air. 
Water in air. 
Hygrometer. SULPHUR AND OXYGEN. 
predicting change of weather. A detailed account of this instrument, 
and of the observations made with it, is given by Mr. Daniell in the 
Quarterly Journal of Science, Vols. viii. ix. and x. 
Section III. Sulphur. 
305. Sulphur, or brimstone, is a brittle substance, of a pale yellow] 
colour, insipid and inodorous, but exhaling a peculiar smell when heat- 
ed. Its specific gravity is 1.990*. It becomes negatively electrical by 
heat and by friction. 
Sulphur is principally a mineral product, and occurs crystallized, its 
primitive form being a very acute Octoedron with an oblique base. 
Its crystals are in a high degree doubly refractive. 
306. When sulphur is heated to about 180°, it volatilizes, and its 
peculiar odour is strong and disagreeable ; at 225Q it liquefies ; be-' 
tween 350° and 400° it becomes viscid, and of a deep brown colour; 
and at about 600° it quickly sublimes. When slowly cooled after 
fusion, it forms a fibrous crystalline mass. It suffers no change by 
exposure to air, and is insoluble in water. It is met with in masses, in 
rolls or sticks, and in the form of powder, when it is usually called, 
Jlowers of sulphur, or sublimed sulphur. 
307. Sublimed sulphur, when examined by a microscope appears 
composed of minute crystals ; it is always slightly sour, and hence, for 
some pharmaceutical purposes, is directed to be washed with hot water. 
308. Massive sulphur is chiefly brought to this country from Sicily ; 
it occurs native, and is found associated with sulphate of lime, sul- 
phate of strontia, and carbonate of lime. Its colour is various shades 
of yellow, and the transparent crystals are doubly refractive ; it is 
not uncommon among volcanic products. 
309. Roll-sulphur is chiefly obtained from sulphuret of copper in 
this country ; which is roasted, and the fumes received into a long 
chamber of brick-work, where the sulphur is gradually deposited : 
it is then purified by fusion, and cast into sticks. In this state, if 
grasped by the warm hand, it splits with a crackling noise. 
310. For some pharmaceutical purposes sulphur is precipitated 
from its alcaline solutions, as from sulphuret of potassa (556) by an 
acid, and, when washed and dried, is in the form of a yellowish-grey 
impalpable powder ; it is the milk of sulphur and precipitated sulphur 
of the Pharmacopwice. Dr. Thomson considers it as a compound of 
sulphur and water.—System of Chcm. Vol. i. 285. 
311. The purity of sulphur may be judged of by heating it gra- 
dually upon apiece of platinum leaf; if free from earthy impurities, 
it should totally evaporate. It should also be perfectly soluble in 
boiling oil of turpentine.—Aikin’s Dictionary, Art. Sulphur. 
312. Sulphur and Oxygen.—Sulphur forms two well-defined com- 
pounds with oxygen, the sulphurous and sulphuric acids ; two other1 
Properties.' 
Action of heatj 
Flowers of 
sulphur. 
Crystallizes. 
How obtain- 
ed. 
Unites wits 
oxygen. 
* The sp. gr. of sulphur vapour compared with oxygen, is the same or equal to 1; now 
1X2 = 2 the atom of sulphur, and 2 is just 16 times 0,125 (the atom of hydrogen.) 112 
compounds of sulphur and oxygen have also been described under the 
names of Hyposulphurous and Hyposulphuric Acids; but these can 
scarcely be said to exist, except in combination with bases, and what is 
known respecting them will be found under the articles Hyposulphite 
of Lime (630) and Hyposulphate of Baryta (639). If they be admit- 
ted as distinct compounds, sulphur may be considered as susceptible of 
four states of combination with oxygen, and these compounds will con- 
sist respectively of 
SULPHUROUS ACIB. 
Sulphurous a- 
cid. 
1 Sulphur 4* 1 
Oxygen 
= Hyposulphurous acid 
1 Ditto 
+ 2 
Ditto 
= Sulphurous acid. 
1 Ditto 
+ 2.5 
Ditto 
= Hyposulphuric acid. 
1 Ditto 
+ 3 
= Sulphuric acid. 
313. Sulphurous acid is a gaseous body, which may be obtained by 
several processes. It may be procured directly, by burning sulphur 
in oxygen gas ; or indirectly, by boiling mercury in sulphuric acid. 
It must be collected and preserved over mercury ; for water takes up 
rather more than 30 times its bulk of this gas, forming the liquid sul- 
phurous acid, which, when recently prepared, has a sulphurous as- 
tringent taste, and destroys many vegetable colours ; but, by keeping, 
it acquires a sour flavour, and reddens the generality of vegetable blues. 
314. If sulphur be burned in oxygen, sulphurous acid is produced 
without any change in the volume of the gas, so that its composition is 
easily learned by the increase of weight; and as 100 cubic inches of 
oxygen (weighing 33.88 grains) dissolve 33.88 grains of sulphur, it is 
obvious that the sulphurous acid is composed of equal weights of sul- 
phur and oxygen ; and if we regard it as consisting of two proportion- 
als of oxygen and one of sulphur, the latter element will be repre- 
sented by the number 16 ; and the sulphurous acid, consisting of 1 pro- 
portional of sulphur =16, and 2 of oxygen = 16, will be represented 
by 32, which is also its relative specific gravity to hydrogen, consider- 
ing the latter as = 1*; 100 cubical inches of sulphurous acid gas weigh 
67.76 grains. This gas has a suffocating nauseous odour, and an as- 
tringent taste ; it extinguishes flame, and kills animals. 
315. Sulphurous acid suffers no change at a red heat, but if mixed 
with hydrogen, and passed through a red hot tube, water is formed and 
sulphur deposited ; under the same circumstances, it is also decompos- 
ed by charcoal, by potassium and sodium, and probably by several 
other metals. Prepared by the combustion of sulphur, it is much 
used for bleaching cotton goods (Quarterly Journal of Science, iv. 196,) 
and also for whitening silk and wool ; in wine countries it is some- 
times used to check vinous fermentation. 
316 When sulphurous acid is mixed in equal volume with ammonia, 
a yellowish salt is produced, which is a sulphite of ammonia, and which 
consists of 32 sulphurous acid + 17 ammonia. When formed by 
saturating liquid ammonia with sulphurous acid, it crystallizes in four 
and six-sided prisms, soluble in their own weight of water and having 
an acrid taste. It is deliquescent, and becomes a sulphate by exposure 
to air. 
* When sp. gr. of oxygen =1, that of sulphurous acid =2 this multiplied by 2 gives 4 for 
the atom of -this acid, also 4 is just 32 times the atom (0.125) of hydrogen. SULPHURIC ACID. 
113 
317. Sulphuric Acid.— This body was formerly obtained by the dis- 
tillation of green vitriol, and called oil- of vitriol. It is now procured 
in this country by burning a mixture of about 8 parts of sulphur and 1 
of nitre in close leaden chambers containing water, by which the fumes 
produced are absorbed, and by evaporation the acid is procured in a 
more concentrated state. This improved method of preparing sul- 
phuric acid was invented by Dr. Roebuck, about the year 1746.— 
Parices’s Chemical Essays, Vol. ii.—Prefatory History of Chemistry. 
Vol. i.p. 36. 
318. Sulphuric acid, as usually met with, is a limpid colourless fluid,, 
having a specific gravity of 1.80 ; it boils at 620°, and freezes at 15°,1 
contracting at the same time considerably in its dimensions. But the 
temperature at which the diluted acid congeals is singularly modified 
by the quantity of water which it contains. At the specific gravity of 
1.78 it freezes at about 40° ; but if the density be either increased or 
diminished, a greater cold is required for its congelation (Keir, Irish 
Phil. Trans, iv. 88.) Its boiling point diminishes with its dilution ; 
acid of the specific gravity of 1.78, boils at 435°, and acid of the spe- 
cific gravity of 1.650 boils at 350u.—Dalton’s Chem. Phil. ii. 404. 
It is acrid and caustic, and when diluted with water, produces a very 
sour liquid. It rapidly absorbs water from the atmosphere, and upon 
sudden mixture with water, condensation ensues, and much heat is evolv- 
ed. Even a boiling temperature, when it is concentrated, does not pre- 
vent its taking up moisture from the air ; hence it cannot be concentrated 
so well in an open as in a close vessel, on which account retorts 
of glass or platinum are used for the last stage of its concentration by 
the manufacturers. 
It chars animal and vegetable substances, and is apt to acquire a 
brown tinge from any small particles of straw, resin, or other matters 
that may accidentally have fallen into it. 
319. In sulphuric acid 1 proportional of sulphur = 16, is combined 
with 3 of oxygen = 24, and, consequently, dry sulphuric acid is cor- 
rectly represented by 16 4* 24 = 40 ; but it only exists in this state 
(like the nitric and chloric acids) when united with bases, and in its or- 
dinary state contains water? and may, therefore, be called hydrated sul- 
phuric Acid. It has been found by experiment, that 100 parts of sul- 
phuric acid, specific gravityjl.85, contain 18.5 of water ; consequently, 
it may be looked upon as composed of 1 sulphur -f* 3 oxygen -f- 1 
water : 
Sulphuric 8- 
cid. 
Or of 16 
sulphur 
24 
oxygen 
9 
water 
49 
number for liquid sulphuric acid. 
100 Parts of liquid sulphuric acid, of the specific gravity of 1.3530, 
contain 37.5 parts of dry sulphuric acid ; or 46 of liquid acid, of the 
specific gravity 1.85. 
320. The strength of sulphuric acid is best judged of by its saturat- 
ing power, and by its specific gravity. Mr. Dalton (JVea> System of 
Chemical Philosophy, Vol. ii. p. 404,) has published a Table, exhibiting 
the specific gravity and boiling point of the acid of various strengths. 114 
SULPHURIC ACID. 
Dr. Ure also has given several valuable tables relating to this subject, 
in his Experiments to determine the Law of Progression, followed in the 
Density of Sulphuric Acid at different Degrees of Dilution (Quarterly 
Journal of Science and the Arts, Vol. iv. p. 114.) An extremely useful 
table of this kind will also be found in Mr. Parkes’s Essays above quo- 
ted (Vol. ii. p. 444.) 
The following is Dr. Ure’s Table : 
Liquid. 
Sp. Gr. 
Dry. 
Liq. 
Sp. Gr. 
Dry. 
Liq. 
Sp. Gr. 
Dry. 
100 
1.8485 
81.54 
66 
1.5503 
53.82 
32 
1.2334 
26.09 
99 
1.8475 
80.72 
65 
1.5390 
53.00 
31 
1.2260 
25.28 
98 
1.8460 
79.90 
64 
1.5280 
52.18 
30 
1.2184 
24.46 
97 
1.8439 
79.09 
63 
1.5170 
51.37 
29 
1.2108 
23.65 
96 
1.8410 
78.28 
62 
1.5066 
50.55 
28 
1.2032 
22.83 
95 
1.8376 
77.46 
61 
1.4960 
49.74 
27 
1.1956 
22.01 
94 
1.8336 
76.65 
60 
1.4860 
48.92 
26 
1.1876 
21.20 
93 
1.8290 
75.83 
59 
1.4760 
48.11 
25 
1.1792 
20.38 
92 
1.8233 
75.02 
58 
1.4660 
47.29 
24 
1.1706 
19.57 
91 
1.8179 
74.20 
57 
1.4560 
46.48 
23 
1.1626 
18.75 
90 
1.8115 
73.39 
56 
1.4460 
45.66 
22 
1.1549 
17.94 
89 
1.8043 
72.57 
55 
1.4360 
44.85 
21 
1.1480 
17.12 
88 
1.7962 
71.75 
54 
1.4265 
44.03 
20 
1.1410 
16.31 
87 
1.7870 
70.94 
53 
1.4170 
43.22 
19 
1.1330 
15.49 
86 
1.7774 
70.12 
52 
1.4073 
42.40 
18 
1.1246 
14.68 
85 
1.7673 
69.31 
51 
1.3977 
41.58 
17 
1.1165 
13.86 
84 
1.7570 
68.49 
50 
1.3884 
40.77 
16 
1.1090 
13.05 
83 
1.7465 
67.68 
49 
1.3788 
39.95 
15 
1.1019 
12.23 
82 
1.7360 
66.86 
48 
1.3697 
39.14 
14 
1.0953 
11.41 
81 
1.7245 
66.05 
47 
1.3612 
38.32 
13 
1.0887 
10.60 
80 
1.7100 
65.23 
46 
1.3530 
37.51 
12 
1.0809 
9.78 
79 
1.6993 
64.42 
45 
1.3440 
36.69 
11 
1.0743 
8.97 
78 
1.6870 
63.60 
44 
1.3345 
35.88 
10 
1.0682 
8.15 
77 
1.6750 
62.78 
43 
1.3255 
35.06 
9 
1.0614 
7.34 
76 
1.6630 
61.97 
42 
1.3165 
34.25 
8 
1.0544 
6.52 
75 
1.6520 
61.15 
41 
1.3080 
33.43 
7 
1.0477 
5.71 
74 
1.6415 
60.34 
40 
1.2999 
32.61 
6 
1.0405 
4.89 
73 
1.6321 
59.52 
39 
1.2913 
31.80 
5 
1.0336 
4.08 
72 
1.6204 
58.71 
38 
1.2826 
30.98 
4 
1.0268 
3.26 
71 
1.6090 
57.89 
37 
1.2740 
30.17 
3 
1.0206 
2.446 
70 
1.5975 
57.08 
36 
1.2654 
29.35 
2 
1.0140 
1.63 
69 
1.5868 
56.26 
35 
1.2572 
28.54 
1 
1.0074 
0.8154 
68 
1.5760 
55.45 
34 
1.2490 
27.72 
67 
1.5648 
54.63 
33 
1.2409 
26.91 
35Vrmstion of 
sulphuric acid 
321. The formation of sulphuric acid by the combustion of sulphur 
and nitre is as follows : 
The sulphur, by burning in contact with atmospheric, air forms sulphu- 
rous acid. The nitre gives rise to the production of nitric oxide, which, 
with the oxygen of the air, produces nitrous acid gas. When these 
gases ([i. e.), sulphurous and nitrous acids) are perfectly dry, they do not SULPHURIC ACID. 
115 
act upon each other, but moisture being present in small quantity, 
they form a white solid, which is instantly decomposed when put into 
water ; the nitrous acid reverts to the state of nitric oxide, having 
transferred one additional proportional of oxygen to the sulphurous 
acid, and, with water, producing the sulphuric acid ; while the nitric 
oxide, by the action of the air, again affords nitrous acid, which plays 
the same part as before. 
Sulphurous acid consists of 
Oxygen 
8. 
Sulphur vapour 
16 
16;== 
Sulphurous acid 
32 
8. 
And nitrous acid contains 
Oxygen 
8. 
Nitrogen 
14 
8. 
32; 
Nitrous Acid 
46 
8. 
8. 
hence every two portions of sulphurous acid require one of nitrous acid, 
which transfers two of oxygen, and passes back into the state of nitric 
oxide, sujphuric acid being, at the same time, produced. 
The gases, therefore, before decomposition, may be thus represent- 
ed : 
16 
Oxygen 
8. 
Oxygen 
8. 
Vapour of 
sulphur 
>16 
Nitrogen 
14 
8. 
8. 
8. 
32 
Vapour of 
sulphur 
16 
8. 
16 
8. 
8. 
Sulphurous add. 
Nitrous acid gas. 116 
SULPHURIC ACID. 
And after decomposition as follows : 
Sulphur vapour 
16 
Oxygen 
8. 
8. 
.241 
Oxvgen 
‘8. 
8. 
Nitrogen 
16 
Sulphur vapour 
16 
Oxygen 
8. 
14 
8. 
8. 
•24 
V 
Nitric oxide. 
8. 
Sulphuric acid. 
Analysis of 
sulphuric acid. 
322. The decomposition of sulphuric acid may be effected by pass- 
ing it through a red-hot platinum tube, when it is resolved into sulphu- 
rous acid, oxygen, and water. 
When heated with charcoal, sulphuric acid gives rise to the produc- 
tion of carbonic and sulphurous acids ; with phosphorus it produces 
phosphoric and sulphurous acids ; and, with sulphur, sulphurous acid 
is the only product. It is decomposed by several of the metals, which 
become oxidized, and evolve sulphurous acid, as shown in the produc- 
tion of this acid, by boiling sulphuric acid with mercury (313), tin, lead, 
4-c. 
323. Sulphuric acid is largely consumed in a variety of manufactures. 
It is used by the makers of nitric, muriatic, citric, and tartaric acids; 
by bleachers, dyers, tin-plate makers, brass-founders and gilders. 
For these purposes it is generally sufficiently pure as it comes from the 
wholesale manufacturer ; but, as traces of lead, lime, and potassa, are 
usually found in it, it often requires to be purified by distillation for the 
use of the experimental chemist. 
The distillation of this acid in glass retorts requires some precaution, 
in consequence of the violent jerks which the production of its vapour 
occasions, and which often break the vessel; this may be prevented 
by putting some strips of platinum into the acid; it then boils quietly, 
and it is only necessary to take care that the neck of the retort and 
receiver are not broken in consequence of the high temperature of the 
condensing acid. This very useful contrivance to the practical che- 
mist was first shpwn me by Mr. James South. 
If the acid of commerce contain dissolved sulphate of lead, it be- 
comes turbid on dilution, so that its remaining clear when mixed with 
water, is some proof of its purity, as far at least as lead is concerned. 
324. When sulphuric acid was procured by the distillation of green 
•vitriol, it was frequently observed that a portion concreted into a white 
Uses. mass of radiated crystals. The same substance has also been remark- 
ed as occasionally formed in the acid of the English manufacturers. 
It has been called glacial ox fuming sulphuric acid, and is by Dr. Thom- 
son considered as the pure or anhydrous acid ; it appears, however, 
probable, that it consists of sulphuric acid, combined with a portion ol 
sulphurous acid.—See Sulphate of Iron (738.) 
325. It has long been an object with the manufacturer to obtain sul- 
phuric acid without the aid of nitre, and a patent has been obtained for 
a process of this kind, invented by Mr. Hill. It consists in submitting 
coarsely-powdered iron pyrites (737) (sulphuret of iron,) to a red 
heat, in cylinders communicating with a leaden chamber containing 
water; the sulphur, as it burns out of the pyrites, appears at once to 
pass into the 6tate of sulphuric acid. 
326. Native Sulphuric Acid has been found by Professor Baldassari, 
in the cavities of a small volcanic hill, called Zoccolino, near Sienna. 
327. When sulphuric acid is dropped into a concentrated and hot 
solution of iodic acid, a peculiar compound is formed, which may be 
termed iodo-sulphuric acid; it is yellow, fusible, and crystallizes on 
cooling in rhomboids ; at a higher temperature it partly sublimes, and 
is partly decomposed. 
328. Sulphuric Acid and Ammonia—Sulphate of Ammonia—may be 
obtained by passing ammonia into sulphuric acid ; but it is usually pre- 
pared by saturating dilute sulphuric acid with carbonate of ammonia, or 
by decomposing muriate of ammonia by sulphuric acid. It is the secret 
sal-ammoniac of some old writers. This salt is important as a source 
of the muriate of ammonia, (292) which is obtained by sublimation from 
a mixture of common salt and sulphate of ammonia; by this process 
sulphate of soda is also formed. 
Sulphate of ammonia dissolves in twice its weight of water at 60°, 
and consists of 1 proportional of sulphuric acid =40 -f* 1 proportional 
of ammonia =17. Its number, therefore, is 57. By crystallization 
it affords six-sided prisms. Its taste is bitter and pungent. When 
heated, it melts and in part sublimes, ammonia is given off, and a super- 
sulphate remains, consisting of 2 proportionals of acid -f* 1 ofalcali. 
329. Native Sulphate of Ammonia is sometimes found in volcanic 
products ; it occurs in stalactitic concretions of a whitish or yellowish 
colour, and covered with a white efflorescence : it has thus been pro- 
cured from fissures in the earth surrounding certain small lakes in 
Tuscany, near Sienna ; and among the products of Etna and Vesuvius; 
it has been termed by Karsten Mascagnine, from the name of its dis- 
coverer. 
330. Sulphur and Chlorine—Chloride of Sulphur. This compound 
was first described by Dr. Thomson, in 1804 (Nicholson’s Journal, 
Vol. vii.) When sulphur is heated in chlorine, it absorbs rather more 
than twice its weight of that gas. 10 grains of sulphur absorb 30 cu- 
bic inches of chlorine, and produce a greenish-yellow liquid, consist- 
ing of 16 sulphur + 36.0 chlorine, and represented, therefore, by the 
number 52. It exhales suffocating and irritating fumes when exposed 
to the air. Its specific gravity is 1.6. It does not affect dry vegeta- 
ble blues ; but when water is present, it instantly reddens them, sul- 
phur is deposited and sulphurous, sulphuric, and muriatic acids are 
CHLORIDE OF SULPHUR. 
117 
Iodo-sulphuric 
acid. 
Sulphate of 
ammonia. 
Chloride of 
sulphur. 118 
SULPHURETTED HYDROGEN. 
formed in consequence of a decomposition of the water. It dissolves 
sulphur and phosphorus. 
- 331. Sulphur and Iodine readily unite and form a black crystallizable 
compound, first described by M. Gay-Lussac.—Annales de Chimie, 91. 
332. Sulphur and Hydrogen—Sulphuretted Hydrogen gas—Hydrothi- 
onic acid.—This gaseous compound of sulphur and hydrogen was dis- 
covered by Scheele in 1777. It may be obtained by presenting sul- 
phur to nascent hydrogen, which is the case when sulphuret of iron is 
acted upon by dilute sulphuric acid. It may also be conveniently ob- 
tained by heating bruised sulphuret of antimony in muriatic acid. 
333. Sulphuretted hydrogen gas may be collected over water, 
though, by agitation, that fluid absorbs nearly thrice its bulk. It has a 
peculiarly nauseous fetid odour, resembling that of rotten eggs. Its 
specific gravity* to hydrogen is as 17 to 1. 100 cubic inches weigh 36 
grains. It is inflammable, and during its slow combustion, sulphur is 
deposited, and water and sulphurous acid formed. It extinguishes 
flame. When respired, it proves fatal; and it is very deleterious, even 
though largely diluted with atmospheric air. It exists in some mineral 
waters. 
334. The aqueous solution of sulphuretted hydrogen is transparent 
and colourless, but if exposed to air it deposits sulphur and the gas es- 
capes. It is an exceedingly delicate test of the presence of most of 
the metals, with which it forms coloured precipitates. It reddens in- 
fusion of litmus ; and as it combines with the greater number of salifi- 
able bases, it has by some been regarded as an acid. Gay-Lussac has 
termed it hydro sulphuric acid. 
335. When one volume of sulphuretted hydrogen, and 1.5 of oxy- 
gen are inflamed in a detonating tube, 1 volume of sulphurous acid is 
produced, and water is formed. Thus the sulphur is transferred to 1 
volume of the oxygen, and the hydrogen to the half volume. Sul- 
phuretted hydrogen, therefore, consists of 16 sulphur 1 hydrogen, 
and its number is 17. Sulphuretted hydrogen may also be decomposed 
by the Voltaic flame, in the apparatus shown at page 80, or by a suc- 
cession of electric sparks. Its volume is unchanged, but the sulphur 
is thrown down. 
336. Chlorine and iodine instantly decompose sulphuretted hydro- 
gen ; sulphur is deposited, and muriatic (248) and hydriodic (259) 
acids are formed. It is also decomposed by the metal potassium, 
which absorbs the sulphur and liberates pure hydrogen, when heated 
in the gas. Nitric acid poured into the gas occasions a deposition of 
sulphur, and nitrous acid and water are formed. 
337. When sulphuretted hydrogen is mixed with its volume of nitric 
oxide over mercury, a diminution of bulk ensues, in consequence of 
the production of water ; sulphur is deposited and nitrous oxide remains 
in the vessel. 
338. When two volumes of sulphuretted hydrogen are mixed in an 
exhausted balloon with one of sulphurous acid, they mutually decom- 
pose each other, occasioning the production of water, and the deposi- 
tion of sulphur ; if the gases be perfectly dry, the action is slow. 
Iodide of sul- 
phur. 
Sulphuretted 
hydrogen. 
* When the specific gravity of oxygen = 1; that of sulph. hydrogen = 1.0625, now twice 
this or 2 125 is the atom, and 2.125 is just 17 times 0.125 (the atom of hydrogen.) SULPHUR AND NITROGEN. 
119 
339. Sulphuretted hydrogen and ammonia readily unite in equal vo- 
lumes, and produce hydro sulphuret of ammonia. At first white fumes 
appear, which become yellow, and a yellow crystallized compound re- 
sults, consisting of 17 sulphuretted hydrogen, -j- 17 ammonia. It is of 
much use as a test for the metals, and may be procured by distilling at 
nearly a red heat, a mixture of 6 parts of slacked lime, 2 of muriate of 
ammonia, and 1 of sulphur. 
340. The following is the disposition of the apparatus for this expe- 
riment : a, a small furnace : h, a tubulated earthen retort containing 
the above materials ; c, an adapting tube ; e, a glass balloon for con- 
densing the vapour ; f, a receiver; g, a bottle of water, into which 
the glass tube, issuing from the upper part of the receiver, e, is made 
to dip about half an inch. 
Hydrosulphu- 
ret of ammo- 
nia. 
The product in the bottle / may be mixed with the water in g, and 
the whole used for washing out the receiver e. In its concentrated 
state, this compound exhales white fumes, as was first remarked by 
Boyle, whence it was termed Boyle's Fuming Liquor, or Volatile Liver 
of Sulphur. It is a deep yellow liquid, smelling like a mixture of sul- 
phuretted hydrogen and ammonia. 
When kept in common white glass vessels it renders them brown or 
black, in consequence of its action on the oxide of lead which the glass 
contains. 
341. Another compound of hydrogen and sulphur which has been 
called supersulphuretted hydrogen, is described in most books as a liquid 
formed by adding muriatic acid to a solution of sulphuret of potassa, 
and it is said to consist of two proportionals of sulphur = 32 -j- 1 
of hydrogen =1. 1 have, however, never been able to obtain it. 
342. Sulphur and Nitrogen do not form any definite compound, 
though the nitrogen evolved during the decomposition of certain ani- 
mal substances, often seems to contain sulphur. 
343. Sulphur, in its ordinary state, always contains hydrogen, which 
it gives off during the action of various bodies for which it has a pow- 
erful attraction. Thus, if equal weights of sulphur and copper or 
iron-filings be introduced into a retort, and heated, a quantity of hydro- 
gen, mixed with sulphuretted hydrogen, is evolved at the period of 
their combination. 120 
phosphorus. 
Section IV. Phosphorus. 
344. Phosphorus is obtained by distilling concrete phosphoric acid 
with half its weight of charcoal at a red heat. This [mixture is put 
into the coated earthen retort a, placed in the small portable furnace b; 
the tube of the retort should be immersed about half an inch into the 
basin of water c. A great quantity of gas escapes, some of which is 
Method of pre- 
paring. 
spontaneously inflammable, and when the retort has obtained a bright 
red heat, a substance looking like wax, of a reddish colour, passes 
over : this, which is impure phosphorus may be rendered pure by 
melting it under warm water, and squeezing it through a piece of fine 
shamoy leather : but great care must be taken that none adheres to 
the nails or fingers, which would inflame on taking them out of the wa- 
ter, and produce a paihful and troublesome burn. It is usually form- 
ed ipto sticks, by pouring it, when fluid, into a funnel tube under water. 
345. In performing this distillation, a high temperature is required, 
so that the furnace should be sufficiently capacious to hold a body of 
charcoal piled up above the retort, which as earthenware becomes 
permeable to the vapour of phosphorus at a red heat, must be coated 
with a mixture of slaked lime and solution of borax ; this mixture may 
be laid on with a brush, in two or three successive coats, and forms an 
excellent vitrifiable lute. 
346. When pure, phosphorus is nearly colourless, semitransparent, 
and flexible. *Its specific gravity is 1.770. It melts, when air is ex- 
cluded, at 105°. If suddenly cooled after having been heated to 140°, 
* The specific gr. of phosphorus vapour compared with oxygen, as the standard is 0.75; 
now this multiplied by 2 gives 1.5 for the atom of phosphorus, and 1.5 is just 12 times 0.125 
(atom of hydrogen.) PHOSPHORIC ACID. 
it becomes black ; but if slowly cooled, remains colourless. At 550° it 
boils, air being excluded, and rapidly evaporates. When exposed to 
air, it exhales luminous fumes, having a peculiar alliaceous odour ; it is 
tasteless, and insoluble in water, but proves poisonous when taken into 
the stomach (Orfila, Traite des Poisons, II., P. ii., p. 186.) In pure 
nitrogen, phosphorus is not in the least luminous at any temperature. 
347. At a temperature of about 100° phosphorus takes fire, and 
burns with intense brilliancy, throwing off copious white fumes. If, 
instead of burning phosphorus with free access of air, it be heated in a 
confined portion of very rare air, it enters into less perfect combustion, 
and three compounds of phosphorus with oxygen are the result, each 
characterized by distinct properties. The first is a red solid, less 
fusible than phosphorus ; the second is a white substance, more vola- 
tile than phosphorus ; the third, a white and more fixed body. 
348. The red solid consists of a mixture of phosphorus and oxide 
of phosphorus. Oxide of Phosphorus is the white substance with which 
phosphorus becomes incrusted when kept for some time in water. It 
is very inflammable, and less fusible and volatile than phosphorus. 
It is this substance which is generally used in the phosphoric match- 
boxes. To prepare it for this purpose, a piece of phosphorus may be 
put into a small phial, and melted and stirred about with a hot iron 
wire so as to coat its interior. A portion of the phosphorus is thus 
oxidized by its imperfect combustion, and a small quantity taken out 
upon the end of a brimstone match, instantly inflames upon coming into 
the contact of the air. 
349. Phosphorus and Oxygen.—Besides the oxide of phosphorus, 
which has just been alluded to, there are three acid compounds of phos-1 
phorus and oxygen, which have been termed hypophosphorous, phospho- 
rous, and phosphoric acids. 
350. Hypophosphorous Acid was discovered by M. Dulong, (Annales 
de Chimie et Physique, Vol. ii. p. 141). It is prepared as follows : 
Upon 1 part of phosphuret of barium (643) pour 4 parts of water, and 
when the evolution of phosphuretted hydrogen gas has ceased, pour the 
whole upon a filter. To the filtered liquid add sulphuric acid as long 
as any precipitate forms ; separate the precipitate, which is a com- 
pound of sulphuric acid and baryta, and the clear liquor now contains 
the hypophosphorous acid in solution. 
When concentrated by evaporation, a sour viscid liquid is obtained, 
incapable of crystallization, and eagerly attractive of oxygen. 
351. Phosphorous Acid was first examined in its pure state, by Sir H. 
Davy. It is best obtained by mixing chloride of phosphorus (364) with 
water and filtering and evaporating the solution, when a white crystal- 
lized solid is obtained, of a sour taste and very soluble. This body 
consists of phosphorous acid combined with water, and has, therefore, 
been called hydro-phosphorous acid. 
35?. Phosphoric Acid may be formed by burning phosphorus in ex- 
cess of oxygen. There is intense heat and light produced, and white 
deliquescent flocculi line the interior of the receiver. It is produced 
in the same way by phosphorus under a dry bell-glass in atmos- 
pheric air.- Phosphoric acid may also be obtained by acting upon phos- 
phorus by nitric acid : in this case, if the acticm be at all intense, a 
portion of ammonia is at the same time produced, which is found in the 
state of phosphate of ammonia in solution. About six parts of nitric 
Union with 
oxygen. 3'HOSPXrORIC ACID. 
acid, specific gravity 1.4, are introduced into a tubulated retort placed 
in a sand heat, with a tubulated receiver luted on to it, the stopper of 
which should be open. When the acid is warm, drop into it gradually 
one part of phosphorus in small pieces ; red nitrous vapour is instantly 
disengaged, and when its evolution ceases, put the stopper loosely into 
the receiver, and distil till the residue in the retort acquires the consist- 
ence of syrup ; pour it into a platinum crucible, and give it a dull red 
heat: it is pure phosphoric acid. 
353. The exposure of phosphate of ammonia (360) to a red heat in 
a platinum crucible, also affords very pure phosphoric acid. 
354. For the purpose of procuring phosphorus, phosphoric acid is 
most economically obtained by the decomposition of bone earth, which 
consists chiefly of phosphate of lime. The following is the mode of 
proceeding : 
On 20 pounds of calcined bone, finely powdered, pour 20 quarts of 
water, and 8 pounds of sulphuric acid, diluted with an equal weight of 
water. Let these materials be stirred together, and simmered for 
about 6 hours. Let the whole be then put into a conical bag of linen 
to separate the clear liquor, and wash the residuum till the water 
ceases to taste acid. Evaporate the strained liquor, and when reduced 
to about half its bulk, let it cool. A white sediment will form wrhich 
must be allowed to subside ; the clear solution must be decanted, and 
boiled to dryness in a glass vessel. A white mass will remain, which 
may be fused in a platinum crucible, and poured out into a clean cop- 
per dish. A transparent glass is obtained, consisting of phosphoric 
acid with some phosphate, and a little sulphate of lime. 
355. Phosphoric acid is a deliquescent substance, and when in the 
flocculent state, as obtained by burning phosphorus under a dry bell- 
glass, it dissolves in water with a hissing noise and excites great heat 
when a small particle is put upon the tongue ; when fused it has been 
called glacial phosphoric acid. It is inodorous, very sour, volatile at 
a bright red heat, but unchanged by it. As commonly prepared, it is 
an unctuous fluid. Specific gravity = 2. (Thomson’s chem. gives 
2.687 for dry phosphoric acid.) 
356. The composition of these acids of phosphorus has been va- 
riously given by different chemists. Sir H. Davy’s most recent ex- 
periments upon this subject, {Phil. Trans. 1818,) appear to furnish the 
least exceptionable results, and he has stated them thus ; 
Method of 
procuring. 
Hypophosphorous acid, Phosphorus 45, 
Oxygen 15 
Phosphorous acid 45 
30 
Phosphoric acid 45 
60 
If these numbers be reduced to the equivalents which I have em- 
ployed, the number representing phosphorus would be 12. The hy- 
pophosphorous acid would then consist of two proportionals of phos- 
phorus = 24, and one proportional of oxygen = 8. The phosphorous 
acid of one of oxygen and one of phosphorous ; and the phosphoric 
of one and two. 
From some experiments which I made in 1816 upon the quantity 
of oxygen absorbed by phosphorus during its conversion into phos- 
phoric acid, by burning it in great excess of oxygen, I was induced to 
believe that, at mean temperature and pressure, each grain of phos- 
phorus condensed rather less than 4.5 cubic inches of oxygen, which PHOSPHORUS AND CHLORINE. 
123 
would give a result differing from that of Sir H. Davy. On the 
whole, however, I am inclined to believe the results of his experiments 
less liable to fallacy than my own ; and adopting the number 12 as re- 
presentative of phosphorus, the phosphorous acid will consist of one 
proportional of phosphorus = 12, and one of oxygen = 8, and will be 
represented by the number 20 : and the phosphoric acid containing 
one proportional of phosphorus and two of oxygen, 12 -J- 16, will be 
represented by 28. 
357. When phosphorus is exposed to a moist atmosphere, it under- 
goes an apparent deliquescence, producing a sour liquid composed of 
phosphorous and phosphoric acids and water. M. Dulong has called 
this phosphatic acid. 
358. Phosphite of Ammonia may be obtained in delicate tabular 
crystals, decomposable by heat, and very soluble. 
359. Hypophosphite of Ammonia has not been examined. 
360. Phosphate of Ammonia is a common ingredient in the urine of 
carnivorous animals. It may be obtained pure by saturating phos- 
phoric acid with ammonia ; it forms permanent octoedral crystals so- 
luble in two parts of water at 60°, and of a bitterish saline taste, 
specific gravity 1.8051. (Thomson’s chem :)— 
Union wills 
< ammonia. 
It consists of 
28 
acid 
17 
ammonia 
45 
This salt is the best source of pure phosphoric acid, for if it he ex- 
posed to a red heat in a platinum vessel, the ammonia evaporates, and 
the acid is obtained in the form of a transparent glass, very deliquescent 
and pure. The phosphate of ammonia for this purpose may be con- 
veniently and economically prepared by saturating the impure acid ob- 
tained from bones (354) with carbonate of ammonia, filtering and eva- 
porating to dryness. 
361. Phosphorus and Chlorine.—These elements unite in two pro- 
portions, forming two definite compounds, the chloride and perchloride 
of phosphorus. 
362. When phosphorus is submitted to the action of chlorine, it 
burns with a pale yellow flame, and produces a white volatile com- 
pound, which attaches itself to the interior of the vessel, and which is 
the perchloride of phosphorus. This substance was long mistaken for 
phosphoric acid, but its easy volatility is alone sufficient distinction; 
it rises in vapour at 200°. It is fusible and crystallizable : and when 
brought into the contact of water, a mutual decomposition is effected, 
(366) and phosphoric and muriatic acids result. When passed through 
a red-hot porcelain tube with oxygen, phosphoric acid is produced and 
chlorine evolved, which shows that oxygen has a stronger attraction 
for phosphorus than chlorine. 
When phosphorus is burned in chlorine, one grain absorbs 8 cubic 
inches ; so that the compound formed must be regarded as containing 
1 proportional of phosphorus, and 2 of chlorine, or 12 of phosphorus 
+ 72 of chlorine, and its number is 84. 
363. With ammonia perchloride of phosphorus forms a singular 
compound, which, though consisting of three volatile bodies, remains 
unchanged at a white heat, and is insoluble in water. 
TJnion with 
chlorine. HYDROGURET OF PHOSPHORUS. 
364. Chloride of Phosphorus, consisting of 12 phosphorus + 36 chlo- 
rine, is procured by distilling a mixture of phosphorus and corrosive 
sublimate, which is a perchloride of mercury. In this experiment ca- 
lomel, or protochloride of mercury, is formed, and the phosphorus 
combines with one proportional of chlorine. 
365. The chloride of phosphorus, when first obtained, is a liquid of 
a reddish colour: but it soon deposits a portion of phosphorus, and 
becomes limpid and colourless. Its specific gravity is 1.45. Expos- 
ed to the air it exhales acid fumes : it does not change the colour of 
dry vegetable blues. Chlorine converts it into perchloride. Ammo- 
nia separates phosphorus, and produces the singular triple compound 
before adverted to (363.) 
366. Chloride of phosphorus acts upon water with great energy, and 
produces muriatic and phosphorous acids, while the perchloride pro- 
duces muriatic and phosphoric acids : for, as in the perchloride there 
are two proportionals of chlorine, so in acting upon water, two of oxy- 
gen must be evolved, wrhich uniting to one of phosphorus generate 
phosphoric acid. The chloride of phosphorus, on the contrary, con- 
taining only one proportional of chlorine, produces muriatic acid and 
phosphorous acid, when it decomposes water, as the following tables 
show: 
Before decomposition. 
Chloride 
of Phosp 
W ater. 
1 Chlorine = 36 ) 48. 
1 Hydrog. = 1 ) q 
1 Phospho. = 12 $ 
1 Oxygen = 8. \ 
After decomposition. 
1 Chlorine 
Muriatic 
Acid. 
= 36 ) 37 
1 Phospho. = 
Phosphorous 
Acid. 
'I 20 
1 Hydrog. 
= l s 
1 Oxygen = 
- But the phosphorous acid, thus produced, always contains water, 
which it throws off when heated in ammonia, forming, with thatalcali, 
a dry phosphite. This experiment shows that the hydrophosphorous 
acid consists of 2 proportionals of phosphorous acid = 40+1 water 
= 9, its number is therefore, 49. 
367. Phosphorus and Iodine.—When these substances are brought 
together in an exhausted vessel, they act violently, and form a reddish 
compound ; the iodide of phosphorus decomposes water with great en- 
ergy, and produces phosphorous and hydriodic acids (257.) It consists 
of 12 phosphorus + 125, iodine — 137. 
368. Periodide of phosphorus is a black compound, formed by heating 
one part of phosphorus with rather more than 20 of iodine. It consists 
according to Dr. Thomson, of 1 proportional of phosphorus + 2 of 
iodine. It does not decompose water. 
369. Phosphorus and Hydrogen.—Phosphuretted Hydrogen.—Hydro- 
guret of Phosphorus.—When phosphorus is presented to nascent hy- 
drogen, two gaseous compounds result. The one inflames spontane- 
ously upon the contact of the atmosphere. This may be procured by 
heating phosphorus in a solution of caustic potassa ; or better, by act- 
ing upon phosphuret of lime (636) by dilute muriatic acid. In the for- 
Hnion with 
iodine. 
Union with 
Biydrogeo. HVDROPHOSFHORie GAS. 
125 
mer case about a quarter of an ounce of phosphorus should he intro- 
duced into a small retort, capable of holding about four ounces of wa- 
ter ; it should then be completely fdled with a moderately strong solu- 
tion of potassa, and the beak being placed under the shelf of the 
pneumatic apparatus, the heat of an Argand lamp carefully applied till 
it boils : gas will gradually be generated so as to expel a portion of the 
alcaline solution, and ultimately to bubble up through the water. 
370. For obtaining this gas by the second process, Dr. Thomson 
gives the following directions : Fill a small retort with water acidulated 
by muriatic acid, and then throw into it a quantity of phosphuret of 
lime in lumps. Plunge the beak of the retort under water, and place 
over it an inverted jar filled with that liquid. Phosphuretted hydrogen 
gas is extricated in considerable quantity, and soon fills the glass jar. 
Half an ounce of phosphuret of lime yields about 70 cubic inches of 
this gas.—Thomson’s System, Vol. i., 272. 
371. This gas is colourless, has a nauseous odour like onions, a very 
bitter taste and inflames when mixed with air, a property which it loses 
by being kept over water; water takes up about two per cent, of this 
gas, and acquires a bitter taste, and the smell of onions. 
372. When bubbles of phosphuretted hydrogen are sent up into a 
jar of oxygen, they burn with greatly increased splendour ; in chlorine 
too they burn with a beautiful pale blue light, forming muriatic acid 
and perchloride of phosphorus. In a narrow tube it may be mixed 
with oxygen without exploding, in which case it is deprived of its 
phosphorus without suffering any change of bulk. It burns when 
thrown up into nitrous oxide. 
373. For our knowledge of the composition of this gas, we are 
chiefly indebted to Dr. Thomson, who has shown that the hydrogen 
suffers no change of bulk in uniting to the phosphorus ; so that the 
difference of weight between this gas and pure hydrogen, indicates the 
weight of phosphorus : 100 cubic inches of phosphuretted hydrogen 
weigh 27.527 grains ; hence the gas may be regarded as containing 
one proportional of phosphorus and one of hydrogen, or 124-1 = 13*. 
When phosphuretted hydrogen is mixed with oxygen, it. requires a 
volume and a half of the latter gas for its perfect combustion ; and as 
the hydrogen would require half its volume of oxygen for the produc- 
tion of water, the remaining volume must unite to the phosphorus to 
produce phosphoric acid. 
374. Bihydroguret of Phosphorus.—Hydrophosphoric Gas.—The 
next compound of phosphorus and hydrogen has been called, by Sir 
H. Davy, hydrophosphoric gas. It is procured by heating the solid 
hydrophosphorus acid in a very small retort. The gas must be col- 
lected over mercury, for water absorbs one-eighth its volume. Its 
specific gravity to hydrogen is as 14 to 1. 100 cubical inches weigh 29. 
645 grains. It is not spontaneously inflammable, but explodes when 
heated with oxygen. It inflames spontaneously in chlorine, one vol- 
ume requiring four of chlorine for its perfect combustion. Its smell 
is less disagreeable than the former. It consists of 2 of hydrogen and 
H P 
1 of phosphorus 24-12=14 ; but the two volumes of hydrogen are 
* When sp. gr. of oxygen= 1, tha, of phosphorus hy drogen = 0.8125, this multiplied by 2 
.gives 1.625 for the atom of phos. hyd, also 1.625 is just Id times 0.125 (atom of hydrogen.) OB CARBON. 
condensed into one ; consequently, when the gas is decomposed, as for 
instance, by subliming sulphur in it, two volumes of sulphuretted hy- 
drogen are formed*. 
375. When hydrophosphorous acid is decomposed for the produc- 
tion of this gas, phosphoric acid is always generated. Hydrophos- 
phorous acid has been stated (366) to contain two proportionals of 
phosphorous acid -f- one of water. Hence the elements 
24 phosphorus = hosphorooa acid 
16 oxygen i r r 1 
1 hydrogen Water- 
or 49.0 parts of hydrophosphorous acid contain 
24 
phosphorus 
24 
oxygen 
1 
hydrogen. 
The three proportionals of oxygen = 24, will require one propor- 
tional and a half of phosphorus = 18, to form phosphoric acid ; and 
the remaining half proportional of phosphorus will unite to the one of 
hydrogen to form hydrophosphoric gas. 
To avoid fractions the phenomena may be stated thus : 
Four proportionals of hydrophosphoric acid contain 
4 phosphorus 
= 
48 
4 oxygen 
= 
32 
2 do. > 
in the — 
16 
2 hydrogen $ 
water = 
2 
The whole of the oxygen, amounting to 6 proportionals (i. e., 8 X 
6 = 48), unites to three proportionals of phosphorus (12X3= 36), 
to form phosphoric acid. The two of hydrogen = 2, combine with 
the remaining proportional of phosphorus = 12 to form hydrophos- 
phoric gas. 
376. Phosphorus and Nitrogen produce no definite compound, 
though in some cases of animal decomposition the evolved nitrogen 
appears to hold phosphorus in solution. 
377. Phosphorus and Sulphur may be readily united by fusion in an 
exhausted vessel. When one proportional of phosphorus is united to 
one of sulphur (12 + 16), the compound bears a high temperature 
without decomposition. It is a crystallizable solid at temperatures 
below 50°.— Faraday. Journal of Science, Vol. iv. p. 361. 
378. By acting upon fused phosphorus by the Voltaic spark, it al- 
ways affords a small portion of hydrogen gas ; this gas is also evolved 
from it, as from sulphur (343) during its union with some of the me- 
tals. 
Union with 
nitrogen. 
Union with 
sulphur. 
Section V. Carbon. 
Diamond. 
379. The purest form of this elementary substance is the diamond, 
a mineral body first discovered in Asia, in the provinces of Golconda 
* Sp. gr. of this gas to oxygen is as 875: 1 now 0.875 X 2 = 1.75 the atom of bihvdrog. 
phos:—this 1.75 is just 14 times 0.125 or the atom of hydrogen. DIAMOND. 
and Visapour in Bengal, and in the island of Borneo. About the year 
1720, diamonds were first found in the district of Serra Dofrio, in 
Brazil. They always occur in detached crystals in alluvial soil. The 
primitive form of the diamond is the regular octoedron, each triangu- 
lar facet of which is sometimes replaced by six secondary triangles, 
bounded by curved lines ; so that the crystal become spheroidal, and 
presents 48 facets. Diamonds, with 12 and 24 facets, are not uncommon. 
(Jameson’s Mineralogy, 2d edit. Vol. i. p. 1). The diamond has been 
found nearly of all colours : those which are colourless are most es- 
teemed ; then those of a decided red, blue, or green tint. Black dia- 
monds are extremely rare. Those which are slightly brown, or tinged 
only with other colours, are least valuable. The fracture of the dia- 
mond is foliated, its laminae being parallel to the sides of a regular oc- 
toedron. It is brittle and very hard ; its specific gravity is 3.5. 
380. The art of cutting and polishing diamonds, though probably of 
remote antiquity in Asia, was first introduced into Europe, in 1456, by 
Louis Bergnen, of Bruges, who accidentally discovered that by rub- 
bing two diamonds together, a new facet was produced. The particu- 
lar process of forming the rough gems into brilliants and rose diamonds 
has been described at length by Jeffries, (Treatise on Diamonds and 
Pearls, 3d edit. London, 1800). By either of these processes, but 
especially by the former, so much is cut away that the weight of the 
polished gem does not exceed half that of the rough stone ; so that 
the value of a cut diamond is esteemed equal to that of a similar 
rough diamond of twice the weight, exclusive of the cost of workman- 
ship. The weight, and therefore the value of diamonds, is estimated 
in carats, 150 of which are about equal to one ounce troy, or 480 
grains. They are divided into halves, quarters, or carat grains, 
eighth, sixteenth, and thirty-second parts. 
381. The difference of value between one diamond and another, 
is, generally speaking, as the squares of their respective weights : 
thus, the value of three diamonds, of one, two, and three carats’ 
weight respectively, is as one, four, and nine. The average price of 
rough diamonds is estimated by Jeffries, at £2. per carat; and, conse- 
quently, when wrought, the cost of the first carat, exclusive of work- 
manship, will be £8., which is the value of a rough diamond of two 
carats. 
A wrought diamond of three carats is worth . . 
.. 
4 carats 
. . 128 
5 ditto 
10 ditto 
20 ditto 
30 ditto 
40 ditto 
. . 12,800 
50 ditto 
60 ditto 
100 ditto 
This mode of valuation, however, only applies to small diamonds, in 
consequence of the difficulty of finding purchasers for the larger ones. 
382. The largest known diamond is probably that mentioned by Ta- 
vernier, in the possession of the Great Mogul. Its size is about that 
of half an hen’s egg; it is cut in the rose form, and when rough, is 
said to have weighed 900 carats. It was found in Golconda about the 
year 1550. CHARCOAL-. 
Among the crown jewels of Russia is a magniticent diamond, weigh- 
ing 195 carats. It is the size of a small pigeon’s egg, and was formerly 
the eye of a Brahminical idol, whence it was purloined by a French 
soldier ; it passed through several hands, and was ultimately purchas- 
ed by the Empress Catharine for the sum of £90,000 in ready money 
and an annuity of £4,000. 
Perhaps the most perfect and beautiful diamond hitherto found, is a 
brilliant brought from India by an English gentleman of the name of 
Pitt, who sold it to the Regent Duke of Orleans, by whom it was plac- 
ed among the crown jewels of France. It weighs rather more than 
136 carats, and was purchased for £100,000. 
383. Another form of carbon is charcoal, the purest variety of which 
is lamp-black. 
Charcoal may be prepared by heating pieces of wood, covered with 
sand, to redness, and keeping them in that state for about an hour. 
They are converted into a black brittle substance, which appears to 
be the same from whatever kind of wood it has been procured. 
Common charcoal employed as fuel is usually made of oak, chesnut, 
elm, beech, or ash wood, the white and resinous woods being seldom 
used. Young wood affords a better charcoal than large timber, which is 
also too valuable to be thus employed. It is formed into a conical pile, 
which being covered with earth or clay, is suffered to burn with a li- 
mited access of atmospheric air, by which its complete combustion, or 
reduction to ashes, is prevented. 
Another, and a more perfect mode of preparing charcoal, consists in 
submitting it to a red heat in a kind of distillatory apparatus consisting of 
cast iron cylinders, from which issue one or more tubes for the escape 
©f gaseous matters. The makers of gunpowder particularly prefer 
this process. (A plate of this apparatus is given by Mr. Parkes, in his 
Chemical Essays.) 
385. Lamp-black is prepared principally by turpentine manufactu- 
rers from refuse and residuary resin, which is burned in a furnace, so 
constructed, that the dense smoke arising from it may pass into cham- 
bers hung with sacking, where the soot is deposited, and from time to 
time swept off, and sold without any fui’ther preparation. (Aikin’s 
Dictionary. Art. Charcoal.) When lamp-black has been heated 
red hot in a close vessel, it may be considered as very pure carbon. 
386. The quantity of charcoal obtained from different kinds of wood 
is liable to much variation. From 100 parts of the following woods, 
Messrs. Allen and Pepys obtained the annexed quantities of charcoal. 
—Phil. Trans. 1807. 
Method of pre- 
paring char- 
coal* 
Beech 
Mahogany 
15.75 
Lignum Vitae 
17.25 
Oak 
17.40 
Fir 
Box 
20.25 
Its properties. 
387. Charcoal is a black, insoluble, inodorous, insipid, brittle sub- 
stance ; an excellent conductor of electricity, but a bad conductor of 
heat; unchanged by the combined action of air and moisture at com- 
mon temperatures ; infusible ; and easily combustible in oxygen gas. 
It is capable of destroying the smell and taste of a variety of vegetable 
and animal substances. (Lowitz, CrelVs Annals, Vol. ii. p. 165). 
The use of charring piles ; of throwing charcoal into putrid water; of 
wrapping it in clothes that have accquired a bad smell; of adding it to CARBONIC OXIDE. 
129 
port wine, with a view of making it tawny ; depends upon the above 
properties. 
388. Newly-made charcoal has the property of absorbing certain 
quantities of the different gases. Upon this subject the experiments 
of M. Theodore de Saussure are the most recent. (Thomson’s 
Annals, Vol. vi.) The charcoal was heated red hot, then suffered to 
cool under mercury, and introduced into the gas. The following are 
the volumes of different gases absorbed by a volume of charcoal = 1. 
Ammonia 
.... 90 
Muriatic: acid 
.... 85 
Sulphurous acid 
Sulphuretted hydrogen.... 
.... 55 
Nitrous oxide 
.... 40 
Carbonic acid 
.... 35 
Bicarburelted hydrogen 
.... 35 
Carbonic oxide 
.... 9.42 
Oxygen .' 
.... 9.25 
Nitrogen 
.... 7.5 
Carburetted hydrogen 
.... 5 
Hydrogen 
.... 1.75 
The absorption was always at its maximum at the end of 24 hours. 
389. The results of these experiments are widely different from 
those of Count Morozzo, (Journal de Physique, 1783) and of M. Rouppe 
(Annales de Chimie, Vol. xxxii.) It would also appear, that this pro- 
perty depends upon the mechanical texture of the charcoal, and conse- 
quently will vary in the different woods ; for by exposing the charcoal 
of different woods to air, Allen and Pepys found that they increased 
very differently in weight. 
By a week’s exposure, Charcoal from 
Lignum Vitse gained 
Fir 
Box 
Beech 
Oak 
Mahogany 
The matter absorbed in these cases consisted principally of aqueous 
vapour, which is very greedily imbibed by newly-made charcoal. 
390. Carbon and Oxygen.—There are two compounds of carbon \ 
and oxygen ; the carbonic oxide and the carbonic acid. 0 
391. Carbonic Oxide is usually obtained by subjecting carbonic acid 
to the action of substances which abstract a portion of its oxygen. 
Upon this principle, carbonic oxide gas is produced by heating in an 
iron retort a mixture of chalk and charcoal ; or of equal weights of 
chalk and iron or zinc filings. It is also obtained by heating a mixture 
of equal parts of oxide of zinc, and charcoal; but the mixture that af- 
fords it most pure, is equal parts of carbonate of baryta and clean iron 
filings ; these should be introduced into a small earthen retort, so as 
nearly to fill it, and exposed to a red heat: the first portion of gas 
being rejected as mixed with the air of the retort, it may afterwards be 
collected quite pure. The gas should be well washed with lime-water, 
and may be preserved over water. The nature of this gas was first 
made known by Mr. Cruickshanks, of Woolwich, in 1802 (Nichol- 
son’s 4to Journal, v.) ; and about the same time it was examined by 
Messrs. Clement and Desormes. Annales de Chimie, xxxix. 
392. Its specific gravity to hydrogen is as 14 to 1 ; 100 cubical inches 
weighing 29.63 grains*. It is fatal to animals extinguishes flame, and 
burns with a pale blue lambent light, when mixed with, or exposed to 
atmospheric air. 
Union with 
oxygen. 
* Specific gravity of oxygen: specific gravity of carbonic oxide : : 1 : 0.875, and 0 875 
X 2 = ] .75 the atom of carbonic oxide, also 1.75 is just 14 times 0.125. CARBONIC ACID. 
393. When a stream of carbonic oxide is burnt under a dry bellr 
glass of air or oxygen, no moisture whatever is deposited, showing 
that it contains no hydrogen. 
394. When two volumes of carbonic oxide, and one of oxygen, 
are acted on by the electric spark, a detonation ensues, and two vo- 
lumes of carbonic acid are produced. Whence it appears, that car- 
bonic acid contains just tw'ice as much oxygen as carbonic oxide, 
which may be considered as a compound of one volume of oxygen 
and one volume of gaseous carbon; or of one proportional of carbon 
and one of oxygen, the latter being so expanded as to occupy two vo- 
lumes. 
395. Carbonic oxide suffers no change by being passed and repass- 
ed through a red-hot porcelain tube ; nor is it decomposed at high 
temperatures by phosphorus, sulphur, nor even, according to the ex- 
periments of Saussure, by hydrogen. (,Journal de Physique, lv.) 
None of the metals exert any action upon this gas, except potassium 
and sodium, which, at a red heat, burn in it by abstracting its oxygen, 
and carbon is deposited. 
396. The representative number of carbon, as obtained by consi- 
dering this gas a compound of one proportional, of carbon vapour and 
one of oxygen, is 6 ; and 6 carbon + 8 oxygen = 14 carbonic oxide. 
397. Carbonic oxide and chlorine combine and produce Chlorocar- 
bonic acid or, Phosgene gas, as it has been termed by its discoverer 
Dr. John Davy, in consequence of the mode of its production. 
By exposing a mixture of equal volumes of chlorine and carbonic 
oxide to the action of light, a condensation =*0.5 takes place. The 
compound has a peculiar pungent odour. It is soluble in water, and 
is resolved into carbonic and muriatic acid gases. The weight of 
chloro-carbonic acid to hydrogen is as 50 to 1. 100 cubical inches 
weigh 105.85 gifciins. It condenses four times its volume of ammonia- 
cal gas, producing a peculiar compound of a white colour.—Phil. 
Trans. 1807. 
|398. Carbonic acid may be obtained by burning carbon, either 
pure charcoal or the diamond, in oxygen gas : the oxygen suffers no 
change of bulk, so that the composition of carbonic acid is easily 
learned by comparing its wreight with that of an equal volume of pure 
oxygen. 100 cubic inches of oxygen weigh 33.88 grains : 100 cubic 
inches of carbonic acid weigh 46.57 grains, or just 22 times as heavy 
as hydrogen, hence 100 cubical inches of carbonic acid must consist 
of 33.88 grains of oxygen, + 12.70 grains of carbon, and 12.7 : 
33.88: :6 : 16. Hence 1 proportional of charcoal = 6 -f- 2 propor- 
Union with 
chlorine. 
* Specific gravity 3.125 (oxygen =1) ; 3.125 X 2 = 6.25 the atom, also, 125 X 5 = 6.25. 
the following diagram will denote its composition. 
Chlorine. 
Carbonic oxide. 
Chlorocarbonic acid. 
36 
14 
50 
f The sp. gr. of Carb. acid compared with oxygen, is as 1.375 :1; now 1.375 X 2=27% 
(the atom) also 2.75 is just 22 times the atom (0.125) of hydrogen. COMBUSTION OP THE DIAMOND. 
131 
Carbon vapour. 
Oxygen. 
Carbonic acid. 
6 
8 -f 8=16 
= 22. 
tionals of oxygen= 16 will constitute carbonic acid, represented by 
the number 22, or by the following symbol. 
399. It is not evident to whom the combustibility of the diamond 
first occurred ; but in the year 1694 the Florentine Academicians 
proved its destructibility by heat by means of a burning lens. The 
;products of its combustion were first examined by Lavoisier in 1772, 
and subsequently with more precision by Guyton Morveau, in 1785. 
{Annales de Chimie, xxxi.) In 1797, Mr. Tennant demonstrated the 
important fact, that when equal weights of diamond and pure charcoal 
were submitted to the action of red hot nitre, the results were in 
both cases the same ; and in 1807 the combustion of the diamond in 
pure oxygen was found by Messrs. Allen and Pepys to be attended with 
precisely the same results as the combustion of pure charcoal. Hence 
the inevitable inference that charcoal and the diamond are similar sub- 
stances in their chemical nature, differing only in mechanical texture. 
400. The following apparatus may be conveniently employed for 
exhibiting the results of the combustion of the diamond. It consists of 
a glass globe, of the capacity of about 140 cubical inches, furnished 
with a cap, having a large aperture ; the stop-cock, which screws into 
this cap, has a jet, a, rising from it, nearly into the centre of the globe ; 
this is destined to convey a small stream of hydrogen, or other inflam- 
mable gas. Two wires, c c, terminate at a very little distance from 
each other, just above this jet, and are intended to inflame the stream 
of hydrogen by electrical sparks ; one of them commences from the 
side of the jet, the other is enclosed and insulated nearly in its whole 
length in a glass tube : the tube and wire pass through the upper part 
of the stop-cock, and the wire terminates on the outside in a ball or 
ring, d, at which sparks are to be taken from the machine, either di- 
rectly or by a chain. On the end of the jet is fixed, by a little socket, 
a small capsule, b, made of platinum foil. This capsule is pierced full 
of small holes, and serves as a grate to hold the diamonds. Its distance 
is about three-quarters of an inch from the end of the jet; and the arm, 
by which it is supported, is bent round, so that the stream of hydrogen 
shall not play against it. The stop-cock screws, by its lower termina- 
tion on to a small pillar, fixed on a stand, and at the side of this pillar is an 
aperture by which a bladder filled with gas may be connected with the 
apparatus. 
On using the apparatus, the diamond is to be placed in the capsule ; 
and then the globe being screwed on to the stop-cock, the latter is to 
be removed from the pillar and placed on the air-pump ; the globe is 
then to be exhausted, and afterwards filled with pure oxygen : or, lest 
the stream of oxygen in entering should blow away the diamond, the 
globe may be filled with the gas first, and then, dexterously taking out 
the stop-cock for a short time, the diamonds may be introduced and the 
stop-cock replaced. The apparatus is then to be fixed on the pillar, COMBUSTION OF THE DIAMOND. 
and a bladder of hydrogen gas attached to the aperture. Now, passing 
a current of sparks between the wires, a small stream of hydrogen is 
to be thrown in, which inflaming, immediately heats the capsule and 
diamonds wrhite hot; the diamonds will then enter into combustion, and 
the hydrogen may be immediately turned off and the bladder detached. 
The diamonds will continue to burn, producing a strong white heat, 
until so far reduced in size as to be cooled too low by the platinum with 
which they lie in contact. 
When the flame of hydrogen is used to heat the diamonds, it is evi- 
dent a little water will be found in the globe, but this is of no conse- 
quence except in attempts to detect hydrogen in the diamond ; the in- 
convenience may be obviated, if required, by using the flame of car- 
bonic oxide. As, however, no hydrogen has at any time been detected 
in the diamond, it is better to use that gas as the heating agent; for 
then the carbonic acid, produced by the combustion, is unmixed with 
that from any other source, and may be collected, and its quantity as- 
certained. 
401. The following method of illustrating the products of the com* 
bustion of the diamond was employed by Messrs. Allen and Pepy’s 
(Phil. Trails. 1807) : a a are mercurial gasometers, one of which is 
filled with pure oxygen gas. The brass tubes h b, properly supplied with 
stop-cocks issue from the gasometers, and are connected with the platinum 
tube c c, which passes through the small furnace d. e is a glass tube 
passing into the mercurio-pneumatic apparatus by which the gas may 133 
be drawn out of the gasometers into convenient receivers. A given 
weight of diamond is introduced into the centre of the platinum tube, 
which is then heated to bright redness, and the gas passed over it, back- 
wards and forwards, by alternately compressing the gasometers. Car- 
bonic acid is soon formed, and it will be found that the increase of 
weight sustained by the oxygen is equivalent to that lost by the dia- 
mond ; that the oxygen undergoes no change of bulk ; and that the 
results are, in all respects, similar to those obtained by a similar com- 
bustion of perfectly pure charcoal. 
COMBUSTION OF THE DIAMOND. 
402. Carbonic acid is a most abundant natural product ; the best 
mode of procuring it for experiment consists in acting upon marble 
(643) (carbonate of lime) by dilute muriatic acid. 
For this purpose the marble, in small fragments, is introduced into 
the two-necked bottle a, and covered with water ; muriatic acid is 
then slowly poured down the funnel b, which causes an immediate ef- 
fervescence, and the gas passes through the bent tube c, into the inverted 
jar d. When the action ceases, it may be renewed by the addition of 
fresh acid, until the whole of the marble is dissolved. 134 
CARBONIC ACID, 
Properties of 
carbonic acid. 
403. Carbonic acid may be collected over water, but must be pre- 
served in vessels with glass-stoppers, since water, at common tempe- 
rature and pressure, takes up its own volume : under a pressure of two 
atmospheres it dissolves twice its volume, and so on. It thus becomes 
brisk and tart, and reddens delicate vegetable blues. By freezing, 
boiling, or exposure to the vacuum of the air-pump, the gas is given 
off. 
404. The effervescent quality of many mineral waters is referable 
to the presence of this gas, and they are often imitated by condensing 
carbonic acid into water, either by a condensing pump, of which a de- 
scription is given by Mr. Pepys (Quarterly Journal of Science and Arts, 
Vol. iv. p. 305) or by a Nooth’s apparatus, as represented in the fol- 
lowing wood-cut. It consists of three vessels, the lowest, a, flat and 
broad, so as to form a steady support; it contains the materials for 
evolving the gas, such as pieces of marble and dilute muriatic acid, of 
which fresh supplies may occasionally be introduced through the stop- 
ped aperture. The gas passes through the tube b, in which is a glass 
valve opening upwards, into the vessel c, containing the water or solu- 
tion intended to be saturated with the gas, and which may occasionally 
be drawn off by the glass stop-cock. Into this dips the tube of the up- 
permost vessel d, which occasions some pressure on the gas in c, and al- 
so produces a circulation and agitation of the water. At the top of d is 
a heavy conical stopper, which acts as an occasional valve, and keeps 
up a degree of pressure in the vessels. CARBONIC ACID. 
135 
iVooth'3 appa- 
i’atus. 
405. Carbonic acid is unrespirable, and it extinguishes flame. 
Its weight may be shown by placing a lighted taper at the bottom of a 
tall glass jar, and then pouring the gas out of a botfle into it, in the manner 
of a liquid ; it descends and extinguishes the flame, and will remain 
a long time in the lower part of the vessel. Hence in wells, and in 
some caverns, carbonic acid frequently occupies the lower parts, while 
the upper parts are free from it. The miners call it choak damp. 
406. The presence of carbonic acid is instantly detected by lime 
'water (621), which it renders turbid, and causes a deposit of a white 
matter, which is carbonate of lime. The addition of water, saturated 
with carbonic acid, to lime water, also occasions a milkiness from the 
same cause. If excess, either of the gas or of its aqueous solution, be 
added to the lime water, the precipitate is re-dissolved, carbonate of 
lime being soluble in carbonic acid (642.) 
407. As all common combustibles, such as coal, wood, oil, wax, tal- 
low, 4’C., contain carbon as one of their component parts, so the com- 
bustion of these bodies is always attended by the production of carbon- 
ic acid. It is also produced by the respiration of animals ; hence it is 
detected, often in considerable proportion, in crowded and illuminated 
rooms, which are ill ventilated, and occasions difficulty of breathing, 
giddiness, and faintness. In the atmosphere it may also be detected 
(303), varying in quantity from 1 to 0.1 per cent. 
408. As carbonic acid is usually retained in combination by very 136 
CARBONATE OF AMMONIA. 
feeble affinity, so it is evolved from most of the carbonates by the sim- 
ple operation of heat. Thus chalk, when heated, gives out carbonic 
acid, and becomes quicklime. It is also evolved from its combinations 
by most of the other acids ; and if nitric, muriatic, or sulphuric acid, 
be poured upon the carbonates, the presence of carbonic acid is indi- 
cated by effervescence. 
409. In Section 398, the nature of carbonic acid has been syntheti- 
cally demonstrated. It may be analyzed by the action of the metal 
■potassium, Vydiich is capable of abstracting its oxygen, and, with the aid 
of heat, burns in it with great splendour ; charcoal is deposited, and 
an oxide of potassium is formed. In this and in some other cases, oxy- 
gen is seen alternately producing acid and alcali. If carbonic acid, 
obtained by burning the diamond in oxygen, be thus decomposed by 
potassium, the carbon makes its appearance in the form of charcoal, 
equal in weight to the diamond consumed. 
410. There are some other substances which at high temperatures, 
are capable of decomposing carbonic acid, and abstracting part of its 
oxygen ; thus, if a mixture of two parts of hydrogen and one of car- 
bonic acid, by volume, be passed through a red-hot tube in the appara- 
tus represented at page 99, water is formed, and carbonic oxide 
passes into the receiver d, mixed with the excess of hydrogen. 
411. If carbonic acid be passed over red-hot charcoal, it becomes 
converted into carbonic oxide by taking up an additional proportion of 
base. The blue flame, often seen upon the surface of a charcoal fire, 
arises from the combustion of the carbonic oxide formed in this way ; 
the air entering at bottom, forms carbonic acid, which, passing through 
the red-hot charcoal, becomes converted into carbonic oxide. 
412. At a bright red heat, iron decomposes carbonic acid, by ab- 
stracting a portion of its oxygen, and forming oxide of iron and carbo- 
nic oxide. 
413. Carbonic acid and ammonia—Carbonate of ammonia.—These 
gases readily combine, and produce one of the most useful and best 
known of the ammoniacal compounds. 
When one volume of carbonic acid and two volumes of ammonia 
are mixed in a glass vessel, over mercury, a complete condensation 
ensues, and a carbonate of ammonia is produced. 
It consists of 17 ammonia -J- 22 carbonic acid, and is represented 
by 39. 
Union tfith 
ammonia. 
Carbonic Acid 
22 
Ammonia 
— 39. 
17 414. II water be present, it so far overcomes the elasticity of the 
gas, as to enable the salt formed to take up another volume of car- 
bonic acid, and thus a bicarbonate is formed. 
415. Carbonate of ammonia crystallizes in octoedrons, though it is 
generally met with in cakes broken out of the subliming vessel, being 
obtained by sublimation from a mixture of muriate of ammonia and 
carbonate of lime. 
The results, however, of this decomposition are not strictly speaking, 
carbonate of ammonia and muriate of lime, but carbonate of ammonia, 
water, and chloride of calcium, the two former being in combination, 
so that a hydrated carbonate of ammonia is always obtained. 
Supposing the materials perfectly dry, the water is formed by the 
union of the hydrogen of the muriatic acid with the oxygen of tin; 
lime, as shown in the following diagram : 
CARBONATE OF AMMONIA. 
137 
Hydrated Carbonate of Ammonia. 
Carbonic 
Acid. 
Ammonia 
Water 
Muriate of 
Ammonia 
Carbonate 
of Lime. 
Muriatic ) Hydrogen 
Acid. $ Chlorine 
ash™* 
416. Mr. Richard Phillips has shown (Quarterly Journal, vii. 294) 
that the carbonate of ammonia of commerce, the ammonia: subcarbonas 
of the Pharmacopaia, is a compound of 
Chloride of Calcium. 
3 Proportionals of Carbonic acid . . 
. . 22 
X 
3 = 66 
2 Ditto Ammonia .... 
. . 17 
X 
2 = 34 
2 Ditto Water 
. . 9 
X 
2 = 11! 
1111 
Its odour is pungent; its taste hot and saline ; it reddens turmeric, and 
renders blues green. A pint of water at 60° dissolves rather less than 
4 ounces. This solution is directed in the Pharmacopoeia, under the 
name of Liquor Ammonia} Subcarbonatis. 
417. By exposure to air, carbonate of ammonia loses its odour, and 
ceases to act upon turmeric paper. In this state it may be considered 
as an hydrated bicarbonate of ammonia, and is composed, according to 
Phillips, of 
2 Proportionals of Carbonic acid . 
. 22 X 2 = 44 
1 Ditto Ammonia .... 
= 17 
*2 Ditto Wntp.r 
. OX 2 = 18 
79 
Omitting the water, therefore, it appears that there are three com- 
pounds of carbonic acid and ammonia. The carbonate composed ot 1 HYDROGURET OF CARBON. 
proportional acid + 1 base ; the sesqui-carbonate composed of 1.5 acid 
+ 1 base ; and the bi-carbonate of 2 acid -j- 1 base. 
418. Carbon and Chlorine.—Mr. Faraday has ascertained that, by ex- 
posing carburetted hydrogen, mixed with great excess of chlorine, to 
the action of light, a white crystalline substance is formed, which, when 
purified b}r washing with water, is a perchloride of carbon. This sub- 
stance is nearly tasteless ; its odour resembles camphor ; its specific 
gravity is about 2 ; it is a nonconductor of electricity. It is volatile, 
and in close vessels fuses at 320°, and boils at 360°. It is not very 
combustible, but burns when held in the flame of a spirit lamp, with 
the emission of much smoke and acid fumes. It is insoluble in water, 
but readily soluble in alcohol and ether ; these solutions deposit arbo- 
rescent and quadrangular crystals. It also dissolves in volatile and fix- 
ed oils. It is scarcely acted upon by alcaline and acid solutions ; but 
most of the metals decompose this substance at a red heat. Potassium 
burns brilliantly in its vapour, causing the deposition of carbon, and 
the production of chloride of potassium. The metallic oxides also de- 
compose it at high temperatures, producing metallic chlorides, and 
carbonic acid or oxide, according to the proportion of oxygen present; 
no water is produced, showing the absence of h}'drogen in the com- 
pound. It appears, from various analytical experiments upon this com- 
pound, among which may be mentioned its decomposition, by passing it 
through red-hot peroxide of copper, that 100 parts afford 10 carbon -j- 
90 chloi’ine ; whence it would appear to consist of 
Union of car- 
bon and chlo- 
rine. 
2 Proportionals of Carbon 
6 X 2 — 12 
3 Ditto Chlorine 
36 X 3 - 103 
120 
419. When the above perchloride of carbon is passed through a 
red-hot tube, containing fragments of rock-crystal to increase the heat- 
ed surface, it gives off a portion of chlorine, tnd is converted into a 
liquid protochloride of carbon. It is a limpid colourless fluid, specific 
gravity 1.55, and not combustible, except retained in the flame of the 
spirit-lamp, when it burns with a yellow flame, much smoke, and fumes 
of muriatic acid. It does not congeal at 0° ; it rises in vapour at about 
165°. It is insoluble in water, but soluble in alcohol, ether, and the 
oils. It is not affected by the acids or alcalis, nor at common tempe- 
ratures, by solutions of silver. It dissolves chlorine, iodine, sulphur, 
and phosphorus. It affords, when decomposed, 17 carbon + 83 chlo- 
rine ; whence it may be inferred to consist of 
1 Proportional carbon 
6 
1 Ditto chlorine .... 
8 13 
11 
Union ■with 
hydrogen 
420. Carbon and Hydrogen—Carburetted Hydrogen—Olejxant Gas— 
Hydroguret of Carbon.—Carbon and hydrogen combine and form ole- 
fiant gas, consisting of 1 proportional of carbon -f- 1 of hydrogen.* 
Its composition will be 12 carbon ) two volumes of each 
2 hydrogen $ condensed to one. 
14 
* Its: specific gravity compared with oxygen, as 0.875 : 1; now 0.875 X 2 = 1.75 $tlie 
atom,) also, 1.75 is just 14 times the atom (0.125) of hydrogen. CARBURETTED HYDROGEN. 
421. It is usually obtained by the decomposition of alcohol by sul- 
phuric acid. For this purpose four parts of the acid and one of 
alcohol are put into a retort, and heated by a lamp. Soon after the 
mixture boils the gas is evolved. It may be collected over wrater ; its 
specific gravity to hydrogen is 14. 100 cubic inches weigh 29.638 
grains. 
422. This gas is inflammable, burning with a bright yellowish 
white flame. One part by volume requires, for perfect combustion, 
three of oxygen, and two of carbonic acid are produced. When 
sulphur is heated in one volume of this gas, charcoal separates, and 
two volumes of sulphuretted hydrogen result. As hydrogen suffers 
no change of volume by combining with sulphur, it follows that ole- 
fiant gas contains two volumes of hydrogen condensed into one, hence 
the quantity of oxygen required for its combustion. 
423. This gas is also decomposed by heat alone, as by passing and 
repassing it through a red-hot tube of earthenware or metal; it then 
deposits its carbon, and is expanded into twice its original volume of 
pure hydrogen. 
424. The following symbols show that one volume or proportional 
of this gas, mixed with three of oxygen, are converted into water and 
carbonic acid, the hydrogen being expanded to two volumes, or its 
real bulk. 
Before detonation. 
C. Hydrogen 
6 + 1 
Oxygen 
8. 
8. 
8. 
After detonation. 
Oxygen 
8. 
Oxygen 
8. 
Carbonic acid 
Hydrogen 
Water 
Carbon 
1. 
6. 
8. 
This gas, therefore, is constituted of 1 proportional of carbon = 6 
-f- 1 proportional of hydrogen — 1, and its number is 7. 
425. When carburetted hydrogen is mixed with chlorine in the pro- 
portion of 1 to 2 by volume, the mixture on inflammation produces 
muriatic acid, and charcoal is abundantly deposited ; hut if the two 
gases he mixed in an exhausted vessel, or over water, they act slowly HYDRIODIDE OF CARBON. 
upon each other, and a peculiar fluid is formed, which appears like a 
heavy oil ; hence this compound has been termed olefiant gas. 
426. Chloric ether is the term applied to this fluid by Dr. Thomson, who 
in 1810, ascertained that its component parts were chlorine and car- 
buretted hydrogen. It has more lately been examined by M. M. Ro- 
biquet and Colin (Annales de Chim. et Phys. Vols. i. and ii.) The 
term hydrochloride of carbon may properly be applied to it. It may 
he formed by allowing a current of each gas to meet in a proper recei- 
ver ; there should be excess of oleliant gas, for if the chlorine be in 
excess, the liquid absorbs it. It is transparent and colourless ; its 
taste, sweet and somewhat acrid ; its specific gravity = 1.2. It 
boils at 152°. It burns with a green flame, evolving muriatic acid, and 
largely depositing charcoal. As it is produced by equal volumes of 
chlorine and carburetted hydrogen, it is probably a compound of one 
proportional of chlorine and two of carburetted hydrogen ; or of 
36 
Carbon 
12 
Hydrogen 
2 
50 
427. From some recent experiments made at the Royal Institution 
by Mr. Faraday, it appears that, by exposing this hydrochloride of car- 
bon to the action of excess of chlorine, muriatic acid and chloride of 
carbon are the results. 
428. When iodine and carburetted hydrogen are exposed to the ac- 
tion of light they combine, and form a hydriodide of carbon. This 
compound was first obtained in the Laboratory of the Royal Institution, 
by Mr. Faraday; and, reasoning analogically upon the facts already 
stated, in respect to the chloride of carbon, it is probable that it may 
lead to the discovery of an iodide of carbon, but that compound has 
not as yet been formed. 
The hydriodide of caibon is a white crystalline solid, volatile with- 
out decomposition, and in many respects analogous to the hydrochlo- 
ride of carbon ; its taste is sweet and its odour aromatic. 
429. A gas, containing carburetted hydrogen, is often generated in 
stagnant ponds ; and by passing the vapour of water over red-hot char- 
coal, or by distilling moist charcoal in an iron retort, at a red heat, and 
washing the gas thus afforded in lime-water, by which the carbonic acid is 
separated, a similar compound is said to be obtained. 
*The specific gravity of these gases is liable to great variation, 100 
cubical inches weighing from 12 to 20 grains. 
They burn with a paler flame, and require less oxygen than olefiant 
gas for perfect combustion. 
>, 430. It has generally been stated that these gases contain a definite 
compound of 1 proportional of carbon and 2 of hydrogen, to which the 
term bi-hydroguret of carbon, or light hydrocarbonate, has been applied. 
From many experiments, however, on this subject, 1 am induced to 
eonsiderthem asmixturesof olefiantgas and hydrogen, since I havenever 
tlnion with 
iodine. 
* The sp. gr. (according to Thomson) is to oxygen as 0.5 : 1; now 0.5 X 2 = 1 (atom) 
also 1 is just 8 times (0.125) the atom of hydrogen, 8 also represents its sp. gr. when hvdro 
gen is taken = 1. GAS ILLUMINATION. 
141 
been able to obtain any other definite compound of carbon and hydro- 
gen, than olefiant gas ; and since they may be imitated by mixtures of 
olefiant and hydrogen gases, of the same specific gravities*. 
431. These mixtures are abundantly produced during the destruc-( 
tive distillation of common pit-coal; and the gas thus obtained is em- 
ployed for the purposes of illumination, as an economical substitute for 
tallow, oil, 4»c. This process is carried on upon a very extensive 
scale in London, in several public and many private establishments. 
The coal is placed in oblong cast-iron cylinders, or retorts, which are 
ranged in furnaces, to keep them at a red heat, and all the volatile pro- 
ducts are conveyed by a common tube into a condensing vessel, kept cold 
by immersion in water ; and in which the water, tar, ammoniacal, and 
other condensible vapours, are retained ; the gaseous products consist 
principally of carburetted hydrogen, sulphuretted hydrogen, and car- 
bonic oxide, and acid: these are passed through a mixture of quick- 
lime and water in vessels called purifiers, by which the sulphuretted 
hydrogen and carbonic gases are absorbed, and the carburetted hydro- 
gen and hydrogen gases, transmitted sufficiently pure for use into gasome- 
ters, whence the pipes issue for the supply of streets, houses, fyc. 
The coke remaining in the retorts is of a very good quality!. 
432. The average specific gravity of purified coal-gas is 0.4500. 
100 cubical inches weigh from 14 to 15 grains, and itmay be consider- 
ed as a mixture of about 55 volumes of hydrogen, and 45 of olefiant 
gas- 
433. The best kind of coal for distillation is that which contains most 
bitumen and least sulphur. The chaldron should yield about 12000 
cubical feet of purified gas, of which each Argand’s burner, equal to 
six wax candles, may be considered as consuming from four to five cu- 
bical feet per hour. 
434. The economy of gas illumination may be judged of by examin- 
ing the value of the products of distillation of a chaldron of coals, the 
average cost of which may be considered as 31. It should afford— 
Coal gas. 
11 
Chaldron of coke, at 25s 1 
n 
3 
24 
Gallons of tar and ammoniacal liquor, at 3d. . . 0 
6 
0 
12000 
Cueic feet of gas, at 15s. per 1000 C.F 9 
0 
0 
17 
3 
These products are taken at their lowest value, but they afford am- 
ple grounds for showing the advantage of gas illumination, not merely 
for public purposes, but also in private establishments. It appears 
that where more than fifty lights are required, a coal-gas apparatus will 
he found profitable. 
* Thomson gives the specific gravity of bihydroguret of carbon or carburetted hydrogen, 
=0.555, which at a mean temperature makes 100 c. i. weigh 16.99 grains—its composition is 
also given. 
Carbon 
. . . 0.416 
Hydrogen . . . 
. . . 0.0694 X 2. • 
. . =(2 vols.) 
f Mr. Parker, of Liverpool, (Phil. Mag. Vol. lii. p. 292,) has proposed to pass the gas as 
it comes from the coal retorts through red-hot iron tubes, by which the contaminating gasas 
and vapours are further decomposed, and the quantity of useful gas much increased. This 
suggestion, if it succeeded, would greatly diminish the quantity of tar, which is the only use 
less product; but as carburetted hydrogen is decomposed at a red heat, it will obviously tenet 
to diminish the illuminating power of the gas, though it will increase its quantity- FIRE-DAMP OF COAL MINES. 
Oil gas. 
435. Messrs. J. and P. Taylor have lately constructed an apparatus 
for the conversion of oil into gas. It consists of a furnace with a con- 
torted iron tube containing fragments of brick or coke, passing through 
it, into which, when red-hot, the oil is suffered to drop ; it is decom- 
posed, and converted almost entirely into charcoal, which is deposited 
in the tube, and into a mixture of carburetted hydrogen, and hydrogen 
gases, of which from two to three cubic feet may be regarded as equi- 
valent to five or six of coal-gas, for the production of light.—Quarterly 
Journal, Vol. viii. 
The commonest whale-oil, or even pilchard-dregs, quite unfit for 
burning in the usual way, afford abundance of excellent gas. requiring 
no other purification than passing through a refrigerator, to free it of a 
quantity of empyreumatic vapour. 
436. A gallon of whale-oil affords about 100 cubical feet of gas, and 
an Argand burner, equal to seven candles, consumes a cubical foot and 
a half per hour. The cost of a lamp fed by oil or coal gas, and giving 
the light of seven candles will be 3 farthings per hour. 
Of Argand’s lamp with spermaceti oil 3d. 
Mould-candles 
3\ 
Wax-candles 
14 
437. By a series of experiments, conducted with every requisite 
caution (Phil. Trans. 1820, p 23,) I found that, to produce the light 
of ten wax candles for one hour, there were required 
2600 cubical inches of pure carburetted hydrogen or olefiant gas. 
4875 oil gas. 
13120 coal gas. 
438. Th5 fitness of the gas obtained from coal for the purposes of 
illumination, is, ceteris paribus, dependent upon the quantity of carbu- 
retted hydrogen, or olefiant gas, which it contains ; and, consequent- 
ly, the fitness of the purified mixed gas for illumination, will be direct- 
ly as its specific gravity ; or, the relative proportion of olefiant gas 
may be judged of by mixing the purified coal gas with twice its volume 
of chlorine over water, by which the olefiant gas will be absorbed, 
and its quantity shown by the amount of the absorption which takes 
place. 
439. Experiments, thus conducted, show that purified coal gas sel- 
dom contains more than 40 per cent, in volume of carburetted hydro- 
gen, while oil gas generally affords about 75 per cent. ; hence its su- 
periority for burning, and the relatively small quantity consumed. 
Dr. Henry (Phil. Trans. 1808,) has given some important experi- 
ments upon the production of gas from coal, by which it appears that 
its composition is very various at different stages of the distillation. 
The mode of distillation also affects the quantity and quality of the 
products. 
440. 'An account of the apparatus for the production of coal gas, 
and ot its construction and expense, will be found in the Treatises on 
Gas Lights, by Mr. Accum and Mr. Peckston. 
441. A mixture of carburetted hydrogen and hydrogen is contained 
abundantly in coal strata, from fissures in which it is sometimes evolved 
in large quantities, forming what in the language of the north country 
miners, is called a blower. When this gas has accumulated in any part of 
Safety lamp. SAFETY LAMP. 
143 
the gallery or chamber of a mine, so as to be mixed in certain proportions 
with common air, the presence of a lighted candle, or lamp, causes it 
to explode, and to destroy, injure, or burn, whatever is exposed to its 
violence. The miners are either immediately killed by the explosion, 
and thrown, with the horses and machinery, through the shaft into the 
air, the mine becoming as it were an enormous piece of artillery from 
which they are projected ; or they are gradually sulfocated, and under- 
go a more painful death from the carbonic acid and nitrogen remain- 
ing in the mine, after the explosion of the fire damp; or what, though 
it appears the mildest, is perhaps the most severe fate, they are burn- 
ed or maimed, and often rendered incapable of labour and of healthy 
enjoyment for life.—Davy, on the Safety-Lamp for Coal Miners, Lon- 
don, 1818. 
Sir H. Davy, in the treatise just quoted, has given a sketch of diffe- 
rent, but ineffectual, contrivances of others, for the prevention of 
these dreadful, and hitherto frequently occurring, accidents ; and has 
described the train of investigation by which he was led to the disco- 
very of a remedy at once simple and efficient, and which has already 
been submitted to repeated and successful trials. 
442. The properties of flame, and the principle of safety adopted in 
this lamp, have already been adverted to (192). It is obvious, from 
what has there been said, that if the flame of a common lamp be every 
where properly surrounded with w'ire-gauze, and in that state immers- 
ed into an explosive gaseous mixture, it w ill be inadequate to its in- 
flammation, that part only being burned which is within the cage, com- 
munication to the inflammable air without being prevented by the cool- 
ing power of the metallic tissue ; so that by such a lamp the explosive 
mixture will be consumed, but cannot be exploded. 
443. The following wood cut is a representation of the Safety lamp, 
as recommended for general use by Sir H. Davy, a is a cylinder of 
wire-gauze, with a double top, securely and carefully fastened, by 
doubling over, to the brass rim b, which screws on to the lamp c.‘ The 
whole is protected and rendered convenient for carrying, by the frame 
and ring d. If the cylinder be of twilled wire-gauze, the wire should 
be at least of the thickness of one-fortieth of an inch, and of iron or cop- 
per, and 30 in the warp, and 16 or 18 in the weft. If of plain wire 
gauze, the wire should not be less than one-sixtieth of an inch in thick- 
ness, and from 28 to 30 both warp and woof.—Davy, on the Safety 
Lamp, p. 114, et seq. 
The operation of this lamp may be shown on a small scale by sus- 
pending it in a glass jar, and then admitting a sufficient stream of coal gas 
to render the enclosed atmosphere explosive. The flame of the lamp 
first enlarges, and is then extinguished, the whole of the cage being fill- 
ed with a lambent blue light; on turning off the supply of gas this ap- 
pearance gradually ceases, and the wick becomes rekindled, when the 
atmosphere returns to its natural state. 
As the safety of these lamps entirely depends upon the perfect state 
of the wire gauze, and upon the non-existence of any aperture or chan- 
nel sufficiently large to admit of the passage of flame, they should, 
when in use in a coal mine, beinspeeted daily to ensure their sound- 
ness in these respects. SAFETY LAMP. 
444. The analysis of a mixture of hydrogen with carburetted hydro- 
gen, carbonic oxide, and carbonic acid, presents peculiar difficulties in 
the ordinary mode of proceeding; and as it often requires to be per- 
formed in investigations relating to the gases used for illumination, it 
became an object to facilitate the process, for which I have used the 
following plan : 
A hundred measures of the gas are introduced into a graduated tube, 
and the carbonic acid absorbed by a solution of potassa ; the remaining 
gas is then transferred to thrice its volume of chlorine of known purity, 
standing over water in a tube of about half an inch diameter, and expos- CVANOGEX. 
145 
cd to daylight, but carefully excluded from the direct solar rays ; after 
24 hours the carburetted hydrogen and the excess of chlorine will have 
been absorbed, and the remaining gas, consisting of carbonic oxide and 
hydrogen, may be analyzed by detonation with oxygen in excess ; the 
measure of carbonic acid formed being equal to that of the original car- 
bonic oxide. 
This proceeding depends upon the non-formation of chlorocarlionic 
(397) acid in a mixture of carbonic oxide and chlorine in the contact of 
water, and out of the direct agency of the solar rays. Such mixture 
1 have kept several days occasionally renewing the chlorine as it be- 
came absorbed by the water, and have not observed any diminution in 
the bulk of the carbonic oxide. In all these cases it is necessary to as- 
certain the purity of the chlorine by its absorption by water, and to be 
aware of the evolution of common air from water during that process. 
445. Carbon and Nitrogen—Carburet of Nitrogen—Cyanogen.—This 
gaseous compound was discovered in 1815, by Gay-Lussac (Annales de 
Chimie, xcv.) It may be obtained from dry and pure cyanuret of mer- 
cury. This substance when heated in a small glass tube to dull redness, 
becomes black, and a quantity of mercury passes over and condenses 
in the cold part of the tube : the gas which is at the same time evolved, 
must be collected over mercury. 
446. It has a penetrating and very peculiar smell, somewhat resem- 
bling that of bitter almonds ; it burns with a beautiful purple flame. *Its 
specific gravity to hydrogen is 26. 100 cubic inches weighing 55. grains. 
Water dissolves 4.5 volumes, and alcohol 23 volumes of this gas. The 
aqueous solution reddens vegetable blues ; and according to Vauquelin 
(Annales de Own., Oct. 1818,) is subject to spontaneous decomposition, 
being gradually converted into carbonic and hydrocianic acids, ammo- 
nia, a peculiar acid, which he calls the cyanic, and a brown substance 
containing carbon ; the ammonia saturates the acids, and the carbona- 
ceous compound is deposited. These changes are referable to the 
mutual re-action of the elements of cyanogen upon those of water. 
447. Cyanogen may be analyzed by detonation with oxygen. One 
volume, detonated over mercury with two of oxygen, produces two vo- 
lumes of carbonic acid, and one of nitrogen. Whence it appears that 
cyanogen consists of two proportionals of carbon = 12. and 1 of nitro- 
gen = 14, the nitrogen having suffered no change of bulk by uniting 
with the carbon ; or it may be said to consist of two volumes of gaseous 
carbon -j- one volume of nitrogen, the three being condensed into one 
volume. Its representative number is 26. 
The following symbols exhibit the mixture of cyanogen with oxygen 
in the above proportions, and the result of their detonation : 
i Union with 
, nitrogen. 
* Its specific gravity is to oxygen as 1.625 : 1; now 1.625 X 2 — 3.25 (its atom.): also, 
3.25 is just 26 times (0.125) the atom of hydrogen. CHLOROCYANIC ACID. 
Before detonation - 
One proportional of Cyanogen and four of Oxygen. 
Oxygen 
8. 
Cyanogen 
C. N. 
12-4-14 
8. 
8. 
8. 
One proportional of Nitrogen. 
After detonation. 
Two proportionals of Carbonic Acid. 
Nitrogen 
Oxygen 
8. 
14 
6. 
8. 
6. 
8. 
8. 
448. Cyanogen and Chlorine combine and produce the Chlorocyanic 
acid. M. Gay-Lussac procured this compound by passing a current of 
chlorine through a solution of hydrocyanic acid (452) in water, till the 
liquid discoloured a diluted solution of indigo in sulphuric acid. He 
then deprived it of excess of chlorine by agitation with mercury. To se- 
parate chlorocyanic acid from this liquid, he took a glass cylinder, filled 
it two-thirds with mercury, and then to the brim with the above liquid, 
and inverted it in a basin of mercury. This basin and cylinder were 
put under the receiver of an air-pump, and the air drawn out, till the 
mercury and liquid were displaced ; the cylinder became filled with 
the vapour of chlorocyanic .acid ; on admitting the air, the vapour con- 
densed into a liquid, and the mercury rose in the cylinder. It may 
also be obtained by carefully distilling the liquid into a receiver sur- 
rounded by ice. 
449. Chlorocyanic acid thus obtained is a colourless and very vola- 
tile liquid, having a peculiar and irritating odour. It reddens litmus ; 
is not inflammable ; and does not form detonating mixtures either with 
oxygen or hydrogen. 
Union of cya- 
nogen and 
chlorine. 450. It appears from the researches of Gay-Lussac, that this acid, 
'in its pure and gaseous state, consists of 1 proportional ofdyanogen -J- 
1 proportional of chlorine, or 26 t 36 = 62. The gases by combi- 
nation suffer no change of volume ; hence the following symbols re- 
present its composition and volume.—Annales de Chimie, xcv. 205. 
HYDROCYANIC ACID. 
Cyanogen 
Chlorine 
Chlorocyanic Acid 
26.0 
36 
62 
451. Iodine and Cyanogen form a volatile solid compound, which col- 
lects in flocculi, and has an acrid taste and pungent smell; it may be 
formed by heating iodine with cyanuret of mercury.—Davy, Quart. 
Journ. i. 289. 
452. Cyanogen and Hydrogen—Hydrocyanic or Prussic acid.—This 
triple compound may be obtained by moistening cyanuret of mercury 
with muriatic acid, and distilling at a low temperature, having surround- 
ed the receiver with ice. 
453. A liquid is thus obtained which has a strong pungent odour, 
very like that of bitter almonds ; its taste is acrid, and it is highly poi- 
sonous. It volatilizes so rapidly as to freeze itself. It reddens litmus. 
The specific gravity of its vapour, compared with hydrogen, is 13.5, so 
that 100 cubic inches weigh 28.579 grains ; detonated with oxygen it 
gives as results one volume of carbonic acid gas, half a volume of hy- 
drogen, and half a volume of nitrogen ; so that it consists of I volume 
of cyanogen -f- 1 volume of hydrogen, and its representative number 
is 27. 
454. The hydrocyanic acid is used in medicine, and several formulae 
have been given for its preparation : the following affords the acid of a 
convenient strength, and is that which is adopted at Apothecaries’ Hall. 
One pound of cyanuret of mercury is put into a tubulated retort with 
six pints of water, and one pound of muriatic acid, specific gravity 1. 
15 ; a capacious receiver is luted to the retort, and six pints are dis- 
tilled over. The specific gravity of the product is 0.995. As this 
acid in its dilute state suffers partial decomposition by keeping, it should 
be prepared in small quantities only for pharmaceutical use and pre- 
served in vessels excluded from light. 
455. It appears from the experiments of Mr. Porrett (Phil. Trans. 
1814,) and from those of M. Gay-Lussac (Ann. de Chim. xcv.) that cy- 
anogen is capable of forming a compound with sulphuretted h}rdrogen. 
It may be obtained by mixing one volume of cyanogen with one and a 
half of sulphuretted hydrogen ; they slowly combine, and form a yellow 
crystallized compound. 
456. According to Dr. Thomson, Mr. Porrett obtained an analogous 
body by a much more circuitous process ; he has termed it sulphur et~ 
ed chyazic acid ; and Dr. Thomson, who regards it as consisting of cy- 
anogen and sulphur only, calls it Sulphocyanic acid.—Syst. V. ii. p. 290. 
He describes it as soluble in water ; of a smell resembling vinegar; 
and decomposed by repeated distillation. 
Union of cya- 
nogen and Io- 
dine. 
Union of cya- 
nogen and hy- 
drogen. 148 
PHOSPHURET OF CARBON. 
457. The compound described by Gay-Lussac consists of two pro- 
portionals of cyanogen, three of sulphur, and three of hydrogen ; Dr. 
Thomson considers it as containing two of cyanogen and three of sul- 
phur ; this would give as its ultimate constituents, 
4 Proportionals of carbon 
. . . 22.3 
2 of nitrogen . . . . 
26.0 
3 of sulphur . . . . 
45.0 
93.8* 
458. Sir H. Davy has noticed the production of a compound of sul- 
phur and cyanogen, obtained by heating a mixture of sulphur and cyan- 
uret of mercury ; and by heating phosphorus with cyanuret of mer- 
cury, a cyanuret of phosphorus appears to be formed. 
459. Carbon and Sulphur—Sulphuret of Carbon. This is a liquid 
obtained by passing sulphur over red-hot charcoal. When purified by 
re-distillation, it is transparent, colourless, and insoluble in water, but 
soluble in alcohol and ether ; its refractive power in regard to light is 
very considerable. Its specific gravity is 1.272. It boils at 106°, and 
does not freeze at—60°. It is very volatile, and has a pungent taste 
and peculiar fetid odour. The cold which it produces during evapo- 
ration is so intense, that by exposing a thermometer bulb, covered 
with fine lint, and moistened with it, in the receiver of an air-pump, the 
temperature sunk, after exhaustion to — 80°. When a mercurial 
thermometer was used, the metal froze. 
460. Sulphuret of carbon is inflammable, and when burned with 
oxygen, produces sulphurous and carbonic acids. It consists of 1 
proportional of charcoal and 2 of sulphur ; 6 -f- 32 — 38. (Berzeli- 
us and Marcet, Phil. Trans. 1813). It was discovered by Lampadius, 
who called it Alcohol of Sulphur.—Crell’s Annals, 1796, ii. 
461. A portion of carburet of sulphur appears to be frequently for- 
med during the production of inflammable gas from coal (431), and to 
be retained in the state of vapour by the gas after its purification by 
lime ; such gas gives a strong sulphurous smell when burned, although 
perfectly cleansed from sulphuretted hydrogen.—Brande, Phil. Trans. 
1820, p. 19. 
462. Carbon and Phosphorus—Phosphuret of Carbon.—To obtain 
this compound* Dr. Thomson directs the following process : (System 
i. p. 276.) Allow phosphuret of lime to remain in water, till it no 
longer evolves gas ; then add to the liquid excess of muriatic acid, agi- 
tate for a few moments, and throw the whole upon a filter. Phosphu- 
ret of carbon remains, which is to be washed and dried. This com- 
pound is a soft powder, of a yellowish colour, without taste or smell : 
exposed to air, it slowly imbibes moisture, and acquires an acid flavour. 
Exposed to a red heat, it burns, and gradually gives out its phosphorus, 
the charcoal being prevented burning by a coating of phosphoric acid. 
It consists of phosphorus 0.62 -f- carbon 0.38 (Thomson’s Annals, 
viii. 157.) These numbers closely correspond with 
Union with 
sulphur. 
Union with 
phosphorus. 
Phosphorus 1 proportional. . . . 
Carbon 1 ditto 
. . . = 12 
6 
18 
* The substance described by Mr. Porrett is evidently distinct from that mentioned by 
Gay-Lussac, which is not sour. But the nature of these compounds is as yet imperfectly 
understood. BORON. 
149 
It would appear from the mode of of obtaining this phosphuret, that 
it forms an ingredient in phosphuret of lime, as usually prepared. 
Section VI. Boron. 
463. This substance is obtained by heating in a copper tube two parts 
of the metal called potassium, with one of boracic acid previously 
fused and powdered. In this experiment the boracic acid, which con- 
sists of boron and oxygen, is decomposed by the potassium. The 
fused matter is washed out of the tube wfith water, and the whole put 
upon a filter. The boron remains in the form of a brown insipid inso- 
luble powder, unaltered by exposure to air at common temperatures, 
but when heated to 600° it burns with much brilliancy, especially in 
oxygen gas, and produces boracic acid. It is a non-conductor of elec- 
tricity. 
464. Boracic acid is usually obtained by dissolving the salt called 
borax in hot water, and subsequently adding half its weight of sulphu- 
ric acid ; as the solution cools, white scaly crystals appear, which, 
when washed with cold water are nearly tasteless, and which consist of 
boracic acid combined with water, and retaining a little sulphuric acid", 
which it loses by exposure to a strong red heat, and fuses into a glass. 
Boracic acid is very difficultly soluble in water ; the solution red- 
dens vegetable blues, but possesses the singular property of render- 
ing the yellow of turmeric brown, in the manner of an alkali. Its 
solution in spirit of wine burns with a green flame. This acid was first 
obtained by Homberg, in 1702, and was used in medicine, under the 
name of Homberg’’s Sedative Salt. Its nature was first shown by Davy, 
in 1807. 
465. The experiments upon the composition of boracic acid are 
much at variance. Berzelius’s determination probably approaches 
nearest to truth : he regards it as containing 1 boron -f- 3 oxygen 
(Thomson’s System, Vol. i. p. 249, 5th edit.) If, therefore, we con- 
sider it as consisting of 1 proportional of boron and 2 of oxygen, the 
number representing boron will be 5, and boracic acid will consist of 
Mode of ob- 
taining. 
1 Boron. 
5.28 
3 Oxygen. 
1G 
Boraic acid. 
21.28 
466. Native boracic acid has been found in the Lipari islands, and 
also in the hot springs of Sasso, in the. Florentine territory ; hence 
the term Sassolin applied to it by some mineralogists. 
467. The boracic acid forms, with ammonia, a Borate of ammonia, 
composed according to Berzelius (Annals of Philosophy, iii. 57,) of 
37.9 5 
Acid 
30.32 
Ammonia. 
31.73 
Water. 
468. Boron burns in chlorine, but the chloride has not been examin- 
ned,- nor have its other compounds been investigated. APPENDIX. 
ENGLISH WEIGHTS AND MEASURES. 
469. The English troy pound is subdivided into twelve ounces, and 
each ounce is equal to 480 grains. The subdivisions of the troy 
ounce, called Apothecaries weight, are into 8 drachms, each drachm into 
3 scruples, and each scruple into 20 grains. The troy ounce is also 
sometimes divided into 20 penny weights, of 24 grains each. These 
are the weights generally employed by chemists, but for philosophi- 
cal purposes ambiguity is most easily avoided by employing the grain 
as integer : and the laboratory should be provided with good sets of 
weights, from one thousand grains downwards ; the grain should be de- 
cimally subdivided into tenths and hundredths. 
470. The standard of most articles bought and sold in common life is 
the avoirdupois pound, which is equal to 7000 troy grains, and is divid- 
ed into 16 ounces, of 437.5 troy grains each. The avoirdupois ounce 
is legally divided into 16 drachms, of 27.34375 grains each ; but this 
division is rejected in all ordinary cases, in consequence of the confu- 
sion likely to result between the troy and avoirdupois drachm, so that 
the term drachm is almost exclusively employed to denote the eighth 
part of a troy ounce, or 60 grains. 
471. For measures of capacity, the wine pint is usually emplo}red, 
which corresponds to 28.875 cubical inches of water, at a temperature 
of 60°. It is subdivided into 16 ounces ; the ounce into 8 drachms. 
Two pints make a quart, and 4 quarts a gallon. 
472. The ale pint contains 35.25 cubical inches of water, at 60°. 
473. For chemical use the most convenient measure is the bulk oc- 
cupied by the troy ounce of distilled water, which may be subdivided 
into 480 grains, and which is equal to 1.8047 cubical inches. 
474. The length of the pendulum, vibrating seconds, in vacuo, in the 
latitude of London (51 ° 34 '8". 4 North at the level of the sea, and at the 
temperature of 62°, is = 32.13929 inches of Sir George Shuckburg’s 
standard scale.—Kater, P/hZ. Trans. 1819, p. 415. 
475. In the following Tables are shown the subdivisions of the Eng- 
lish troy and avoirdupois pounds, and of the English wine gallon,and 
iheir correspondence with-the French gramme and litre. WEIGHTS AND MEASURES. 
ENGLISH WEIGHTS AND MEASURES. 
476. Troy Weight. 
Pound. Ounces. 
Drms. Scruples. 
Grains. 
Grammes. 
1 = 12 = 
; 96 = 288 = 
5760 
= 
372.96 
1 = 
: 8 = 24 
480 
== 
31.08 
1 = 3 == 
60 
= 
3.885 
1 = 
20 
1.295 
1 
= 
0.06475 
Pound. Ounces. Drms. 
Grains. 
Grammes* 
1 __ 16 256 — 
7000 
= 453.25 
1 = 16 = 
437.5 
= 28.328 
27.34375 
= 1.770'S 
477. Avoirdupois Weight. 
478. Wine Measure. 
Gal. 
Pints. Ounces 
. Drms. Cub. Inch. 
Litres. 
1 
8 = 128 
*= 1024 = 231 = 
3 78515 
1 = 16 
= 128 =a 28.875 t= 
0.47398 
1 
= 8 =a 1.8047 = 
0.02957 
1 => 0.2256 =*= 
0.00396 
FRENCH WEIGHTS AND MEASURES. 
479. The French metrical system is founded on a single standard of 
length, called a metre, and which is equivalent to the ten millionth part 
of the arc of the meridian, extending from the equator to the pole. 
The length of the metre, at the temperature of 32°, as ascertained by 
Captain Kater {Phil. Trans. 1818,) is 39.37079 English inches. 
480. The French measures increase and decrease in decimal pro- 
portions, a distinctive prefix being put to the term by which the inte- 
ger is called. These prefixes are deca, hecto, kilo, and myria, taken 
from the Greek numerals, to express the multiplication of the integer 
by 10, 100, 1000, and 10000 respectively : and deci, centi, and milli, 
from the Latin numerals, to express the division of the integer by 10, 
100, or 1000 ; as in the following Table : 
Metres. 
1 Myriametre 
==. 10000 
1 Kilometre. . 
= 1000 
1 Hectometre 
= 100 
1 Decametre 
=1 10 
1 
Metre .... 
Metre. 
1 
1 
Decimetre . 
. => 
0.1 
1 
Centimetre . 
0.01 
1 
Millimetre . 
. =a 
0.001 
481. The metre is the integer of the measure of length, and from 
it all measures of surface, capacity, and weight, are deduced as follows. 
For square dimensions, the metre, or its parts squared, are employ- 
ed. When used for measuring land the term are is adopted, which is a 
decametre squared. A hectare, or 100 arcs, is about equal to 2 English 
acres. 
For the integer of the measure of capacity, the cubed decimetre is 
employed, under the name of litre, which is about equal to 2| English 
wine pints. 
For the integer of the measure of weight, the weight of a cubic cen- 
timetre of distilled water, at 32°, has been adopted : it is called a gram- 
me, and is equal to 15.4 English grains. 
482. The following are the principal Tables of French Weights and 
Measures, which will be found useful in the laboratory. In Appendix 
II. of Aikin’s Dictionary, the chemical reader will find several others 
showing the relation of the French to the English standards : WEIGHTS AND MEASURES. 
FRENCH WEIGHTS AND MEASURES. 
483.—Measures of Length, 
English Inches. 
Millimetre 
8=2 
.03937 
Centimetre 
C= 
.39371 
Decimetre 
=3= 
3.93710 
Metre 
= 
39.37100 
Mil. 
Fur. 
Yds. 
Feet. 
In. 
Decametre 
393.71000 
= 0 
0 
10 
2 
9.7 
I lecatometre 
ass 
3937.10000 
== 0 
0 
109 
1 
1 
Kilometre 
= 
39371.00000 
— 0 
4 
213 
1 
10.2 
Myriometre 
= 
393710.00000 
= 6 
1 
156 
0 
6 
484.—Measures of Capacity. 
Millilitre 
Cubic Inches. 
.06103 
English. 
Centilitre 
= 
.61028 
Decilitre 
= 
6.10280 
Tons. Hogs. Wine G. Pints. 
Litre 
= 
61.02800 
= 0 0 0. 2.1133 
Decalitre 
= 
610.28000 
= 0 0 2. 5.1352 
Ilecatolitre 
= 
6102.80000 
= 0 0 26.419 
Kilolitre 
= 
61028.00000 
= 10 12.19 
Myriolitre 
= 
610280.00000 
= 10 1 58.9 
485.—Measures of Weight. 
Milligramme 
Centigramme 
Decigramme 
= 
English grains. 
.0154 
.1544 
1.5444 
Avoirdupois. 
Gramme 
= 
15.4440 
Poun. Oun. 
Dram. 
Decagramme 
= 
154.4402 
= 00 
5.65 
H ecatogramme 
= 
1544.4023 
= 03 
8.5 
Kilogramme 
= 
15444.0234 
= 23 
5 
Myriogramme 
= 
154440.2344 
= 22 1 
2 
TABLE OF THE SPECIFIC GRAVITY OF WATER, AT EVERY DEGREE OF 
TEMPERATURE, FROM 30° TO 80° FAHR. 
486. The following Table is given by Mr. Gilpin, in the 84th vol- 
ume of the Philosophical Transactions, and is of essential use for taking 
the specific gravities both of solids and fluids, by enabling the operator 
to reduce the weight or bulk of the distilled water, employed in any case, 
to that which it would have at any other common temperature, and par- 
ticularly to 60°, which is the usual standard. 
487. Thus, for example, since the specific gravity of water at 47° is 
1.0008, and at 60° is 1.00000, and (consequently 10008 grains, at 47°, 
are equal in bulk to 10000 grains at 60°,) it follows that it would re- 
quire 252.708 grains, at 47®, to equal the space of a cubic inch ; for 
10000 : 10008 :: 252.506, (the weight of a cubic inch at 60°,) : 252.708. 
488. The remarkable anomaly of the specific gravity of water decreas- 
ing through all the degrees of temperature below 40®, or thereabouts, 
that it remains uncongealed, has been noticed under the article Heat 
(60) ; but the difference for one or two degrees above or below 40° is 
so trifling, that it has hardly yet been ascertained with perfect accuracy. APPENDIX. 
153 
489. TABLE OF THE SPECIFIC GRAVITY OF WATER. 
AT EVERY DEGREE OF TEMPERATURE, FROM 30° TO 80° FAHR. 
Fahr. 
30° 
Specific Gr. 
1.00074 
31 
- 
- 
- 
1.00078 
32 
- 
- 
- 
1.00082 
33 
- 
- 
- 
1.00085 
34 
- 
- 
- 
1.00088 
35 
- 
- 
- 
1.00090 
36 
- 
- 
- 
1.00092 
37 
- 
- 
- 
1.00093 
38 
- 
- 
- 
1.00094 
39 
. 
- 
- 
1.00094 
40 
- 
- 
- 
1.00094 
41 
- 
- 
- 
1.00093 
42 
- 
- 
- 
1.00092 
43 
- 
- 
- 
1.00090 
44 
- 
- 
- 
1.00088 
45 
- 
- 
- 
1.00086 
46 
- 
- 
- 
1.00083 
47 
- 
- 
- 
1.00080 
48 
- 
- 
- 
1.00076 
49 
- 
- 
- 
1.00072 
50 
- 
- 
- 
1.00068 
51 
- 
- 
- 
1.00063 
52 
- 
- 
- 
1.00057 
53 
- 
- 
- 
1.00051 
54 
- 
- 
- 
1.00045 
55 
- 
- 
- 
1.00038 
Fain*. 
56° 
Specific Gr, 
1.00031 
57 
- 
- 
- 
1.00024 
58 
- 
- 
- 
1.00016 
59 
- 
- 
- 
1.00008 
60 
- 
- 
- 
1.00000 
61 
- 
- 
- 
0.99991 
62 
- 
- 
- 
0.99981 
63 
- 
- 
. 
0.99971 
64 
- 
- 
- 
0.99961 
65 
- 
. 
- 
0.99950 
66 
- 
- 
, 
0.99939 
67 
- 
- 
. 
0.99928 
68 
- 
- 
0.99917 
69 
- 
- 
- 
0.99906 
70 
- 
- 
. 
0.99894 
71 
- 
- 
- 
0.99882 
72 
- 
- 
- 
0.99869 
73 
- 
- 
- 
0.99856 
74 
- 
- 
- 
0.99843 
75 
- 
- 
- 
0.99830 
76 
- 
- 
- 
0.99816 
77 
- 
- 
- 
0.99802 
78 
- 
- 
- 
0.99788 
79 
- 
- 
- 
0.99774 
80 
- 
- 
- 
0.99759 
TABULAR VIEW OF SPECIFIC GRAVITIES, REPRESENTATIVE OF 
EUQ.UI VALENT NUMBERS, fyc. 
490. The following Table shows, at one view, the specific gravities 
of the simple substances described in this volume, and of their mutual 
combinations ; it also exhibits their equivalent numbers, and the pro- 
portions in which they combine. TABULAR VIEW Of 
TABULAR VIEW of the Specific Gravities, and Equivalent Numbers of thf Supporters of 
Combustion and Acidifiable Substances and of the Compounds which they form 
with each other. 
too 
Cubic Inches 
weigh grs- 
Specific Gravity compared to 
1 Equivalent 
N'lmht 
1 
SUBSTANCES. 
Hydrogen 
Air. 
W a ter 
COMPOSITION 
491. 1. Oxygen 
33.88 
16 
1.1111 
8 
76.25 * 
76.25 
36. 
2.5 
36 
31.75 
.444444 
68. 
32 oxy. + 36 chi. 
40 oxy. 4" 36 chi. 
56. oxy. -f- 36. chi. 
76 
92 
264.625 
125 
8.6805 
4.948 
125 
40 oxy. 4- 125 iodine. 
36 chi. -f- 125 iodine. 
161. 
2.117 
25295.3 
1 
.0694 
1 
Water 
11242.3 
837.55 
1 
9.0 
8 oxv 4" 1 hy. SPECIFIC GRAVITIES, $*C. 
SUBSTANCES 
too 
Cubic Inches 
weigh grs. 
Specific Gravity compared to 
Equivalent COMPOSITION 
Number 
Hydrogen 
Air 
W ater 
19,05 
39.162 
9. 
18.5 
0.625 
1.2851 
1343.3 
37. 
36 chi. *f 1 hy. 
480 vol. of gas. 
125 iode -J- 1 hy. 
14 nit. -f- 8. oxy. 
14 nit. ~j~ 16 oxy. 
14 nit. 4- 32 oxy. 
14 nit. -f 40 oxy. 
54. nit ac. -{- 18 w. 
14 n. -f 144 chlo. 
21 oxy. +• 79 n. 
Muriatic acid gas 
1.21 
' 
133.37 
29.625 
46.574 
31.756 
48.69 
63 
14 
22. 
15 
23. 
4.375 
.9721 
1.52725 
1.0428 
2.13566 
126. 
14 
22. 
30 
46 
54. 
72. 
158 
Nitric acid (dry) 
Nitric acid (liquid) 
1.5 
1.6 
Chloride of nitrogen 
Common air .... 
30.5 
14.4 
1 
Supporters of Combustion and Acidijiable Substances (continued.) TABULAR VIEW OF 
SUBSTANCES 
too 
Cubic Inches 
weigh grs. 
Specific 
Hydrogen 
Gravity compar 
Air 
ed to 
Water 
Equivalent 
Number 
CO IPOSITION. 
. 
18. 
8.5 
.596 
17. 
14 n. 4- 3 hy. 
.875 
670 volumes. 
93 
76 chi. ac. + 17 am. 
Iodate of ammonia 
1.45 
54. 
Hydriodate of ammonia 
143. 
17 am. -f- 126 hy. a. 
1.5785 
71 
17 am. + 54 n. a. 
Atmospheric air 
1.99 
16 
Hyposulphurous acid 
24. 
16 sul. -f 8 oxy. 
Hyposulphite of ammonia 
41. 
17 am. + 24 hyposul. a. 
Sulphurous acid 
67.5 
30 
2.235 
32 
16 sul. -+• 16 oxy. 
Supporters of Combustion and Acidifiable Substances (continued.) SPECIFIC GRAVITIES, fyc. 
SUBSTANCES 
too 
Cubic Inches 
weigh grs. 
Specific Gravity compared to 
Equivalent 
Number 
COMPOSITION 
Hydrogen 
Air 
Water 
81 
40 
49 
57. 
52. 
17 
51 
12 
32 
17 am. -f- 64 sul. acid. 
16 sul. -J- 24 oxy. 
40 s. a.-f- 9 water. 
40 s. a. -f-17 am. 
16 sul. + 36 chi. 
16 sul.+ 1 hy. 
34 s. h.-f-17am. 
24 P. -f- 8 oxy. 
Hypo-sulphuric acid 
1.9 
1.6 
Iodide of sulphur 
Sulphuretted hydrogen . 
36 
17 
1.92 
/ 
497. IV. Phosphorus 
1.77 
Oxide of phosphorus 
Supporters of Combustion and Acidi/iable Substances (continued.) TABULAR VIEW OF 
SUBSTANCES 
100 
Cubic Inches 
weigh grs. 
Specific 
JHydrogen 
Gravity com par 
Air 
ed to ! 
W ater 
Equivalent 
Number 
COMPOSITION 
of ammonia 
20 
49 
37. 
28 
45 
48 
84 
14 
13 
40 
12 P. -j- 8 oxy. 
40 P. a.-4-9- water. 
20 P. a. -f-17 am. 
12 P. 416 oxy. 
28 P. a. -f 17 am. 
12 P.-f 36 chi. 
12 P.4.72 chi. 
P. 12-fhy. 2. 
P. 12-fhy. 1. 
P. 244 sul. 16. 
2.85 
1.45 
Iodide of phosphorus 
Hydro-phosphoric gas 
Phosphuretted hydrogen 
29.645 
27.527 
14 
13 
.9685 
.894 
Supporters of Combustion and Acidifable Substances (continued.) SPECIFIC GRAVITIES, <$’C. 
159 
SUBSTANCES 
100 
Cubic Inches 
weigh grs. 
Specific Gravity compared to 
Equivalent 
| Number 
COMPOSITION 
Hydrogen 
Air 
Water 
3.5 
6. 
• 1 
29.63 
14 
.9834 
14 
Carb. 6 -j- oxy. 8. 
105.85 
50 
3.47915 
50 
C. Ox. 14 + chi. 36. 
46.464 ' 
22 
1.54215 
22 
Carb. 6 4 oxy. 16. 
39 
C. a. 22-f-am. 17. 
Sesquicarbonate of ammonia 
_. r 
61 
C. a. 44-{-am. 17. 
1.55 
42 
Carb. 6 -j- chi. 36. 
2. 
Carb. 12 4 chi. 102. 
Carburetted hydrogen (olefiant) 
30.15 
13.4 
.9983 
7 
Carb. 6.-f hy. 1. 
Hydrochloride of carbon 
1.2201 
50 
Olef. 14 4 chi. 36, 
Hydriodide of carbon 
Cyanogen 
55 
26 
1.8178 
26. 
Carb. 12.4-n. 14 
Supporters of Combustion and Acidijiable Substances (continued.) SPECIFIC GRAVITIES, 4'C. 
SUBSTANCES 
100 
Cubic Inches 
weigh grs. 
Specific 
Hydrogen 
Gravity compar 
Air 
ed tc 
Water 
Equivalent 
Number 
COMPOSITION 
Chloro-cyanic acid 
Hydro-cyanic acid 
Hydro-cyanate of ammonia 
Sulphocyanic acid 
65.1375 
28.579 
31 
13,5 
2.152775 
.94615 
1.272 
62. 
27. 
38 
6. 
22 
39 
57 
Cy. 26 -J- ch. 36. 
Carb. 12.-{.nit. 14-f-hy. 1. 
Carb. 6-f-sul. 32. 
B. 6. -J- oxy. 16 
B. a. 22. -f-w. 17. 
B. a. 22.-{-am. 17.-f-w. 18. 
Phosphuret of carbon 
499. VI. Boron 
1.803 
1.479 
Supporters of Combustion and Acidifable Substances (continued.) TABLE SHOWING THE CONNEXION BETWEEN THE 
ATOMS OF GASES AND THEIR SPECIFIC GRAVITIES. 
(Deduced from Thomson’s paper in the annals of Philos. Vol. 16, for the 
year 1820.) 
GASES. 
Itom of hy- Specific gra- 
! drogen that | vities com- 
1 of oxvgen j pared with 
biin/—1. hydrogen. 
Specific gravi- 
ties compared 
with oxygen. 
Multiples. 
Atoms com- 
pared with 
oxygen. 
Chlorine 
0.125 
X 
36 
= 
2.2500 
X 
2 = 
4.500 
Hydrogen 
X 
1 
= 
0.0625 
X 
2 = 
0.125 
Nitrogen ...... 
0.125 
X 
14 
= 
0.8750 
X 
2 = 
1.750 
Steam 
X 
9 
= 
0.5625 
X 
2 = 
1.125 
Protoxide of nitrogen . . 
0.125 
X 
22 
= 
1.3750 
X 
2 - 
2.750 
Iodine vapour 
0.125 
X 
125 
= 
7.8125 
X 
2 = 
15.225 
Sulphur vapour .... 
0.125 
X 
16 
= 
1.0000 
X 
2 = 
2.000 
Sulphurous acid .... 
0.125 
X 
32 
= 
2.0000 
X 
2 = 
4.000 
Sulphuretted hydrogen . 
0.125 
X 
17 
= 
1.0625 
X 
2 = 
2.125 
Phosphorus vapour . . . 
0.125 
X 
12 
= 
0.7500 
X 
2 = 
1.500 
Phosphuretted hydrogen 
0.125 
X 
13 
= 
0.8125 
X 
2 = 
1.625 
Bihydroguret of Phosphorus 
0.125 
V 
✓ N 
14 
= 
0.8750 
X 
2 = 
1.750 
Carbon vapour .... 
0.125 
X 
6 
= 
0.3750 
X 
2 = 
0.750 
Carbonic oxide .... 
0.125 
X 
14 
= 
0.8750 
X 
2 = 
1.750 
Chloro carbonic acid . . 
0.125 
X 
50 
= 
3.1250 
X 
2 = 
6.250 
Carbonic acid 
0.125 
X 
22 
= 
1.3750 
X 
2 = 
2.750 
Olefiant gas 
0.125 
X 
14 
0.8750 
X 
2 = 
1.750 
Carburetted hydrogen . . 
0.125 
X 
8 
0.5000 
X 
2 = 
1.000 
Carburet of nitrogen . . 
0.125 
X 
26 
1.6250 
X 
2 = 
3.250 
Note. From the above it will be seen, that all the gases there mentioned, have their atoms 
just double their specific gravities, when oxygen is taken as the standard for both; further, 
that every atom is exactly a multiple by a whole number of the atom denoting Hydrogen, 
and that this whole number, is always the number of times which each gas weighs an equal 
bulk of hydrogen; or, in other words, its specific gravity when compared with hydrogen. 
The following few gases are exceptions to the foregoing laws though, they also, follow a re- 
gular order. 
GASES. 
Atom of hy- 
drogen (oxy- 
gen) = 1. 
Sp. gr. com- 
pared with 
hydrogen. 
Sp. gr. com- 
pared writh oxy- 
gen. 
Multiples. 
Atoms com- 
pared with 
oxygen. 
Oxygen 
Ammonia 
Deutoxide of nitrogen . . 
Muriatic acid gas .... 
Hydriotic acid . 
Nitrous acid gas .... 
Protoxide of chlorine . . 
0.125 X 8(4) =1 1.000 
0.125 X 17.(twice)=0.5.3125X4= 2.125 
0.125X 30.ftwice)=0.93.75 X4= 3.750 
0.125X 37.(twice) = 1.1560 X4= 4.625 
0.125 X 126.(twice)=3.9375 X 4=15.750 
0.125X 30.(twice)=0.9375 X4= 3.750 
disagrees with the rest 
Note. The brackets contain the proportions which the foregoing numbers under the 
2nd column bear to their specific gravities when compared with hydrogen, thus 8 is 
the specific gravity of oxygen, and 17 double that of ammonia. It will be seen that with 
one exception (oxVgen) the numbers in the column of multiples of this table arc, indi- 
vidually, double those in the same column of the first table; and further that (with the 
same exceptions) the multiple of the atom of hydrogen in this last table is just double 
the specific gravity; whereas, in the first, its multiple is, throughout, exactly the specific 
gravifv. general properties 
CHAPTER V. 
OK THE METALS, AND THEIR COMBINATIONS. 
601. THE metals constitute a numerous and important class of sim- 
ple substances ; many of them were diligently examined by the older 
chemists, who have left us valuable information concerning them ; 
many are of more recent discovery ; and the existence of several 
others has been demonstrated within the last twenty years. 
1 Gold 
2 Silver 
3 Copper 
4 Iron 
5 Mercury 
6 Tin 
7 Lead 
8 Zinc 
9 Bismuth 
10 Antimony 
11 Arsenic 
12 Cobalt 
13 Platinum 
14 Nickel 
15 Manganese 
16 Tungsten 
17 Tellurium 
18 Molybdenum 
19 Uranium 
20 Titanium 
21 Chromium 
The metals are forty-two in number. 
22 Columbium 
23 Palladium 
24 Rhodium 
25 Iridium 
26 Osmium 
27 Cerium 
28 Potassium 
29 Sodium 
30 Lithium 
31 Barium 
32 Calcium 
33 Strontium 
34 Magnesium 
35 Silicium 
36 Alumium 
37 Yttrium 
38 Glucium 
39 Zirconium 
40 Thorinum 
41 Selenium 
42 Cadmium 
.Number of 
metals. 
602. Of these metals the first seven were known in very remote 
ages. The ancients designated them by the names of the planets, to 
which they were supposed to have some mysterious relation ; and each 
was denoted by a particular symbol, representing both the metal and 
the planet. 
Gold was the Sun, and was thus represented 
© 
Silver . . 
Moon 
5 
Mercury . 
Mercury 
s 
Copper. . 
Venus 
9 
Iron . . . 
Mars 
s 
Tin. . . . 
Jupiter 
n 
Lead . . . 
Saturn . 
h 
Ancient sym- 
fcels. OF THE METALS. 
163 
Zinc was not known to the ancients, though they were probably ac- 
quainted with its ores, and with their property of forming brass when 
fused with copper. (Pliny, Lib. xxxiv. cap. 2 and 10.) The word 
Zinc first occurs in the writings of Paracelsus, who died in 1541. Bis- 
muth is mentioned in the Bermannus of Agricola, written about 1530. n 
Antimony was first obtained in its pure state by Basil Valentine towards0 
the end of the 15th century. The process is described in his Currus 
Triumphalis Antimonii. Arsenic and Cobalt were discovered by 
Brandt in 1733, (Acta Upsal. 1733 and 1742) ; their ores were known 
at a much earlier period. Platinum was first recognised as a peculiar 
body in 1741, by Mr. Charles Wood, Assay-Master in Jamaica. {Phil. 
Trans. Vol. xliv.) In 1751, the distinctive characters of Nickel were 
shown by Cronstedt (Stockholm Transactions), and Manganese was ob- 
tained by Gahn in 1774. (Bergman’s Opuscula, Vol. ii.) Tungsten 
was discovered by M. M. Delhuyart in 1781. {Memoires de Toulouse). 
Tellurium and Molybdenum by Muller and Hielm, in 1782. Uranium 
by Klaproth in 1789. Titanium by Mr. Gregor, in 1789. Chro- 
mium by Vauquelin, in 1797. (Annales de Chimie, Vol. xxv.) In 
1802, Mr. Hatchett discovered Columbium. {Phil. Trans.) Palla- 
dium and Rliodium were discovered by Dr. Wollaston ; and Iridium 
and Osmium by Mr. Tennant, all in 1803. {Phil. Trans.) Cerium 
was announced in 1804 by M. M. Hisinger and Berzelius. (Gehlen’s 
Journal, ii.) Potassium and Sodium were discovered in 1807 by Sir 
H. Davy, whose experiments also led to the discovery of the metallic 
nature of the ten following bodies. Thorinum and Selenium were 
announced by Berzelius in 1815 and in 1817 ; and Mr. Stromeyer, of 
Gottingen, discovered Cadmium in 1818. 
503. The circumstances under which metals are found in the earth, 
will be stated in the chapter of this work relating to geology. It may 
here be remarked, that they seldom occur in an uncombined state, but 
almost always united to other substances, as in the four following 
classes :— 
i. Native metals are those which occur pure or alloyed, and have 
but a feeble attraction for oxygen ; such as platinum, gold, silver, mer-i 
cury, and copper. 
ii. Metals combined with simple supporters of combustion. The com-, 
pounds belonging to this class are chiefly native metallic oxides : there- 
are also a few native chlorides, but no iodides have hitherto been dis- 
covered. The fluorides, of which there are a few, may also be re- 
garded as belonging to this class. 
iii. Metals combined with simple inflammables. This class includes - 
the native metallic sulplmrets, a very numerous and important series ofJ 
ores. One native carburet only is known, that of iron. There are no 
native hydrurets, phosphurets, nor borurets. 
iv. Metals in combination with acids—Metallic salts. Of these the. 
most common are the native carbonates, sulphates, and phosphates: there 
are a few native borates; and a few species belong also to this class in 
which the oxide is united to a metallic acid: such as the native arse- 
niates, chromates, tungstates, and molybdates. 
504. The metals, as a class, are characterized by a peculiar lustre and i 
perfect opacity : they are excellent conductors of heat, (74) and of' 
electricity (102.) 
505. There is the greatest difference in the specific gravity of the 
different metals, the heaviest and lightest solids being included in the list. 
Times of dis- 
covery. 
Natural com- 
binations. 
—With simple 
supporters of 
combustion. 
! —With sim- 
pple inflamma- 
‘ bles. 
—with acids. 
I General 
practeristics. The principal metals, arranged according to their specific gravities, 
Stand as follow : 
GENERAL PROPERTIES 
1 Platinum 21.00 
2 Gold 19.30 
3 Tungsten 17.50 
4 Mercury 13.50 
5 Paladium 11.50 
6 Lead 11.35 
7 Silver 10.50 
8 Bismuth 9.80 
9 Uranium • 9.00 
10 Copper 8.90 
11 Arsenic 8.35 
12 Nickel 8.25 
13 Cobalt 8.00 
14 Iron 7.78 
15 Molybdenum 7.40 
16 Tin 7.30 
17 Zinc 7.00 
18 Manganese i- 6.85 
19 Antimony 6.70 
20 Tellurium 6.10 
21 Sodium 0.972 
22 Potassium 0.865 
Order of spe- 
cific gravities. 
506. The specific gravity of solids and liquids is always expressed 
in numbers referring to water as = 1. 
To ascertain the specific gravity of solids we employ a delicate ba- 
lance, so contrived as to admit of substances being attached to one of 
the scales by means of a horse-hair or a fine thread of silk. The ab- 
solute weight of the body thus suspended is then very carefully ascer- 
tained : it is next immersed in distilled water, of the temperature of 
60° ; and the beam being again brought to an equilibrium, we learn 
the weight lost by its immersion ; or, in other words, we ascertain the 
weight of its bulk of pure water. We now divide the sum of its abso- 
lute weight by that of the weight which it lost in water, and the quo- 
tient is its specific weight, or gravity, compared with water of the tem- 
perature of 60". 
Suppose a substance, weighing 360 grains, to lose 60 by immersion 
in water, the specific gravity of that substance will be = 6 ; for 360 
•f 60 = 6. 
507. For ascertaining the specific gravity of liquids, we generally 
em doy a thin phial, holding 1000 grains of distilled water, at the tem- 
perature of 60°'. If filled with any other liquid, and weighed, we 
learn its specific gravity ; thus we should find that it would contain 
13500 grains of mercury ; 1850 grains of sulphuric acid ; 1420 grains of 
nitric acid, which numbers of course represent the specific gravi- 
ties of those liquids. 
A bottle, however, holding 1000 grains is often inconveniently 
large, and a small and thin globular phial, with a piece of thermometer 
tube ground into it by way of stopper, will be found more useful: 
such a phial should not weigh more than from 50 to 60 grains, and 
Method of de- 
termining spe- 
cific gravity. 
Of solids. 
'Of fluids. OF TUB METALS. 
may contain between 4 and 500 grains of water. To use it, it should 
be accurately counterbalanced in a delicate pair of scales, and then 
filled with distilled water, and the stopper thrust in, the capillary 
opening in which allows a little to ooze out, and prevents the likeli- 
hood of bursting the phial; it is then to be wiped clean and dry, and 
again carefully weighed, by which the quantity of water it contains is 
ascertained ; the water being poured out, it is next filled with the li- 
quid whose specific gravity is required, taking care that it is of the 
same temperature as the water; we then weigh as before, and divide 
the weight by the former weight of water, the product gives the spe- 
cific gravity required. Thus, suppose the phial to contain 425 grains 
of water at the temperature of 45°, it will be found to hold 5737.5 
grains of pure mercury of the same temperature ; and 5737.5 -f- 425 
= 13.5 the specific gravity of mercury. Or, supposing the liquid 
lighter than water, such as alcohol, of which we may assume the phial 
to contain 350.5 ; then 350.5 425 = 0.824 the specific gravity of 
the alcohol under trial. 
508. Among the metals, some are malleable, others brittle. 
Malleability, or the capacity of being extended by the hammer be- 
longs to the following metals, in the order following : 
Malleability. 
Gold 
Silver 
Copper 
Tin 
Cadmium 
Platinum 
Lead 
Zinc 
Iron 
Nickel 
Palladium 
List and order 
of malleable 
metals. 
Potassium, sodium, and frozen mercury, are also malleable. 
509. The malleable metals are also ductile ; that is, they admit of 
being drawn out into wires. They are arranged according to ductili- 
ty as follows ; 
Gold 
Silver 
Platinum 
Iron 
Copper 
Zinc 
Tin 
Lead 
Nickel 
Paladium. 
Of ductile m* 
tals. 
510. Different metallic wires are possessed of different degrees of 
tenacity, by which is meant the power of supporting a weight without 
breaking. According to the experiments of Guyton Morveau, the 
following are the weights capable of being sustained by wires yVoVths 
>f a line in diameter.—Annales de Chimie, lxxi.: 
A wire of Iron suppports . . . 
lbs. decimal 
avoird. parts. 
549.250 
Copper ...... 
302.278 
Platinum 
274.320 
Silver 
187.137 
Gold 
150.753 
Zinc 
109.540 
Tin 
34.630 
Lead 
27.621 
Metals pos- 
sessing tenaci- 
ty, with the 
power of each. 166 
GENERAL PROPERTIES 
511. The folowing metals are brittle : 
Antimony 
Arsenic 
Bismuth 
Cerium 
Chrome 
Cobalt 
Columbium 
Manganese 
Molybdenum 
Tellurium 
Tungsten 
Titanium 
Uranium. 
Brittle metals. 
512. None of the metals are very hard, and many so soft as to yield 
to the nail. In the following table some of the metals are arranged in 
the order of their hardness ; 
Tungsten 
Palladium 
Manganese 
Iron 
Nickel 
Platinum 
Copper 
Silver 
Bismuth 
Gold 
Zinc 
Antimony 
Cobalt 
Tin 
Arsenic 
Lead. 
Order of their 
hardness. 
Elasticity and sonorousness belong to the hardest metals only. 
Such are the essential physical characters of the metals ; they also 
resemble each other in many of their chemical properties, as the fol- 
lowing general observations show : 
513. Action of Heat.—The metals are all susceptible of fusion by 
heat, but the temperatures at which they liquefy are extremely va- 
rious. Mercury is fluid at all common temperatures, and requires to 
be cooled to—39° before it congeals. Potassium melts at 150°, and 
sodium at 200° : arsenic at 360° ; tin at 450° ; lead at 600° ; zinc at 
700° ; and antimony at 300°. Silver, gold, and copper require a 
bright cherry-red heat; iron, nickel, and cobalt, a white heat; man- 
ganese and palladium, an intense white heat ; molybdenum, uranium, 
tungsten, and chrome, are only very imperfectly agglutinated at the 
highest temperatures of our furnaces ; and titanium, cerium, osmium, 
iridium, rhodium, platinum, and columbium, require the intense heal 
produced by an inflamed current of oxygen and hydrogen, or that of 
Voltaic electricity. 
At higher temperatures than that required for their fusion many of 
the metals are volatile, and may be distilled in close vessels. Mer- 
cury, arsenic, potassium, tellurium, and zinc, are volatile at a dull red 
heat. Gold and silver are converted into vapour when exposed* to 
the intense heat of the focus of a burning lens ; and several of the 
other metals boil and evaporate under similar circumstances. It is 
probable that this would happen to all of them, if raised to sufficiently 
high temperatures. 
514. Action of Oxygen.—When the metals are exposed at ordinary- 
temperatures to the action of oxygen, or of common air, which pro- 
duces analogous, though less powerful effects, they are very differently 
effected. If the gas be perfectly dry, very few of them suffer any 
change unless heated in it; the}' then lose their metallic characters, 
and form a very important series of compounds, the metallic oxides. 
Actionof heat. 
Action of oxy-1 
gen. OF THE METALS. 
A few of the metals resist the action of heat and air so completely, 
that they may be kept in fusion in an open crucible for many hours 
without undergoing cnange. This is the case with gold and silver, and 
a few others ; hence they were called perfect or noble metals : they 
may, however, be oxidized by the Voltaic flame ; or by passing a 
strong electric discharge through them, when drawn into very fine 
wire. 
Other metals readily absorb oxygen when exposed to a temperature 
approaching a red heat ; as iron, mercury, nickel, 4*c. ; others absorb 
it when in fusion, as lead, tin, antimony, 4*c. ; others at lower, or even 
at common temperatures, as arsenic, manganese, sodium, potassium, 4'c. 
That the metals have very different attractive powTers in regard to 
oxygen is also shown by the circumstance of one metal being frequent- 
ly oxidized at the expense of another; thus the oxide of mercury, 
heated with metallic iron, produces metallic mercury and oxide of 
iron ; potassium, heated with oxide of manganese, becomes oxidized, 
and metallic manganese is obtained. 
Some of the oxides are decomposed by mere exposure to heat, as 
those of gold, mercury, #c.; others require ..the joint action of heat, 
and some body having a high attraction for oxygen, such as charcoal. 
Thus when oxide of lead is heated with charcoal, carbonic acid gas is 
evolved, and metallic lead obtained. 
Each metal has a certain definite quantity of oxygen with which it 
combines ; and were the same metal unites in more than one propor- 
tion with oxygen, in the second, third, and other compounds, it is a 
multiple of that in the first, consistent with the law of definite propor- 
tions (46). Thus 100 parts of mercury combine with 4 of oxygen to 
produce the protoxide, and with 8 to produce the peroxide. Copper 
also forms two oxides ; in the one 12.5 of oxygen are united to 100 of 
metal, and in the other 25. 
Among the combinations of metals with oxygen, some are insoluble 
in water, or nearly so, and have neither taste nor smell; others are so- 
luble and sour, constituting the metallic acids : others are soluble and 
alcaline, forming the fixed alcalis and alcaline earths. They are of all 
colours, and frequently the same metal united to different proportions 
of oxygen produces compounds differing in colour : thus we have the 
black and red oxide of mercury, the white and the black oxide of man- 
ganese, &rc. 
515. Action of Chlorine.—All the metals appear susceptible of com- 
bining with chlorine, and of producing a class of compounds which 
may be termed metallic chlorides. 
There are a few of the metals which resist the action of chlorine at 
common temperatures, but when heated they all combine with it; some 
slowly, others rapidly and with intense ignition. Copper leaf, powder- 
ed antimony, arsenic, burn when thrown into the gas : mercury 
and iron inflame when gently heated in it ; silver, gold, and platinum 
quietly absorb it. 
The attraction of chlorine for metals is greater than that of oxygen ; 
consequently, when a metallic oxide is heated in chlorine, oxygen is 
evolved, and a chloride formed. The insoluble chlorides are also 
formed by adding solution of chlorine, or of the soluble chlorides, or 
©f muriatic acid, to the soluble metallic salts. Thus chloride of silver, 
Action of chlo- 
rine. GENERAL PROPERTIES 
which is insoluble, is thrown down from the soluble nitrate of silver by 
solution of chlorine, of muriatic acid, and of common salt. 
The physical and chemical properties of the chlorides are extreme- 
ly various. They are nearly of all colours. Some are unchanged by 
heat; others undergo decomposition. Some are soluble, others inso- 
luble, in water. Several of them decompose water, giving rise to the 
formation of muriatic acid, and an oxide ; or in some cases to a mu- 
riate. The same metal often forms more than one compound with 
chlorine, and these compounds are designated as the oxides. Thus 
we have the protochloride and perchloride of mercury, $*c. 
Many of the metals decompose muriatic acid in which case hydro- 
gen is evolved, and a metallic chloride produced ; and when metallic 
oxides are heated in muriatic acid, they generally give rise to the for - 
mation of a chloride and water. 
516. Action of Chloric Acid.—The compounds of the metallic ox- 
ides with chloric acid are decomposed by heat with the copious evolu- 
tion of oxygen, and a chloride generally remains : some of these salts 
have been long known, others only recently investigated. The oxy- 
chlorates have been scarcely examined. 
517. Action of Iodine.—Iodine aided by heat acts upon many of the 
metals, and produces metallic iodides. Some of these are soluble in 
water without decomposition ; others decompose water and produce 
hydriodates; others are insoluble. The insoluble iodides may gene- 
rally be formed by adding a solution of iodine or of hydriodic acid to 
the soluble metallic salts. 
Iodine often combines in more than one proportion with metals, 
forming a protiodide and a periodide. 
518. Action of Iodic Acid.—The compounds of this acid with the 
metallic oxides have been but little examined : they are decomposed 
by heat, sometimes with the evolution of oxygen only ; at others, io- 
dine is also given off. 
519. Action of Hydrogen.—Hydrogen forms permanent compound? 
with twro of the metals only, namely, arsenic and tellurium. It ap- 
pears to combine with each in two proportions, forming two solid com- 
pounds, the hydrurets or hydrogurets of arsenic and tellurium ; and 
two gaseous compounds, arseyiuretted and telluretted hydrogen. At high 
temperatures it dissolves potassium, forming potassiuretted hydrogen 
gas. 
There are many of the metallic oxides, and a few of the chlorides, 
which are decomposed by hydrogen : the oxides are reduced with the 
formation of water, and the chlorides with the production of muriatic 
acid. 
520. Action of Water.—Those metals which are speedily acted upon 
by common air and oxygen, are also generally susceptible of decom- 
posing water ; some of them rapidly, others slowly. There are some 
metals which are not acted upon by air deprived of moisture, nor by 
water deprived of air ; but moist air, or water containing air, effect 
their oxidizement: this appears to be the case with iron.—Dr. Mar- 
shall Hall. Quarterly Journal, vii. 55. 
Water combines with some of the metallic oxides, and produces hy- 
drated oxides, or metallic hydrates. In these the relative proportion 
of water is definite. Some are easily decomposed by heat, as hydrate 
of copper ; others retain water even when heated to redness, as hy- 
drate of potassa. 
Action of chlo- 
ric acid. 
Action of Io- 
dine. 
Action of Io- 
dic acid. 
Action of hy- 
drogen. 
Actspo of wa- 
ier; OP THE METALS. 
169 
521. Action of Nitric Acid.—As no metal is soluble in tut acid ex- 
cept in the state of oxide, and as the greater number of metals arei 
capable of decomposing nitric acid, and of resolving it into some of 
the other nitric compounds, nitric acid is a very generally acting sol- 
vent of these bodies. It dissolves all the metallic oxides and produces 
a numerous class of nitrates, which if prepared with heat and with 
excess of acid, generally contain the metal at its maximum of oxidize- 
ment. The nitrates are all decomposed by a red heat; they give off 
oxygen and nitrogen, either separate, or combined, and the metallic 
oxide remains. They are also decomposed when heated with sulphur, 
phosphorus, or charcoal; and sulphurous, phosphoric, and carbonic 
acids are formed ; the phosphoric, being a fixed acid, remains united 
to the metallic oxide ; while the sulphurous and carbonic acids are 
usually expelled. The nitrates are decomposed by sulphuric acid, 
nitric acid is evolved, and sulphates are formed. 
In the neutral nitrates the proportion of oxygen in the acid is to that 
in the base as 5 to 1. Thus in the nitrate of potassa 48 parts of po- 
tassa, containing 8 of oxygen, are combined with 54 of nitric acid, 
containing 40 of oxygen ; and in the pernitrate of copper, 80 parts 
of peroxide of copper containing 16 of oxygen, are combined with 
108 of nitric acid, containing 84 of oxygen. 
522. Action of Ammonia.—At high temperatures some of the metals 
are capable of decomposing ammonia. Liquid ammonia dissolves se- 
veral of the metallic oxides, and with some of them forms crystalli- 
zable compounds. The compounds of ammonia with the oxides of 
gold, silver, and platinum, detonate when heated, and the oxide and 
the ammonia are both decomposed. 
523. Action of Sulphur.—All the metals appear capable of forming 
sulphurets. These are in some cases formed by heating the metal with 
sulphur ; in others, by decomposing the sulphates ; and in others, by 
the action of sulphuretted hydrogen. The sulphurets are in general 
brittle ; some have a metallic lustre ; others are without lustre. Some 
are* soluble, others insoluble in water. Where the same metal forms 
two sulphurets, the sulphur in those containing the largest proportion 
is an exact simple multiple of the sulphur in those containing the small- 
est proportion. When the metallic sulphurets are heated some under- 
go no change, as those of sodium and potassium ; others sublime un- 
altered as sulphuret of mercury ; others lose a portion ot their sulphur, 
and, if air be admitted, sulphurous acid escapes and the metal passes 
into the state of oxide, as sulphuret of lead ; others again are entirely 
decomposed, the metal being completely reduced ; this happens on 
heating sulphuret of platinum or of gold. It is doubtful whether any 
definite compounds of sulphur with the metallic oxides exist. 
524. Hyposulphurous acid combines with the metallic oxides and 
produces a class of salts termed hyposulphites. Several of these have 
been examined by Mr. Herschel (Edinburgh Philosophical Journal, i.) 
In some of their characters they resemble the sulphites : they are 
easily soluble ; of a bitter or sweet taste ; and decomposed by a heat 
below redness, and by almost all other acids. Their solutions readily 
dissolve chloride of silver. 
525. Sulphurous acid combines with many of the metallic oxides, 
producing sulphites; in some instances oxygen is transferred from the 
oxide to the acid, and sulphates result. 
Action of til- 
trie acid. 
Action of sul' 
phur. 
SuipkfteS. 170 
GENERAL PROPERTIES 
The sulphites are soluble in water, and have a sulphurous taste and 
smell. Exposed to moist air, they absorb oxygen, and pass into the 
state of sulphates. They are decomposed by sulphuric acid, which 
expels sulphurous acid, and the salts are converted into sulphates. 
When perfectly pure they are not affected by solution of baryta. 
526. Hyposulphuric acid forms with the metallic oxides a class of hy- 
posulphates which have been very imperfectly examined. They do 
not afford precipitates with solution of baryta. 
527. Sulphuric acid, in its concentrated state, is acted upon by a few 
of the metals only ; when diluted, some of them are oxidized at the 
expense of the water, hydrogen is evolved, and the metallic oxide com- 
bines with the acid, producing a sulphate. In these cases the hydro- 
gen evolved is the indicator of the quantity of oxygen transferred to 
the metal; every volume of hydrogen is the equivalent of half a volume 
of oxygen, and accordingly the production of 100 cubic inches of hy- 
drogen, indicates the transfer of 50 of oxygen, or by weight of about 
17 grains. As different metals unite to different weights of oxygen, 
they will obviously evolve different quantities of hydrogen. Thus, if 
one metal, to become soluble in sulphuric acid, require to be united 
with 15, and another with 30 per cent, of oxygen, the latter will evolve 
twice the volume of hydrogen, compared with the former. 
As the evolution of hydrogen, during the solution of a metal in dilute 
sulphuric acid, is referable to its oxidizement, no hydrogen will be 
evolved by the action of the acid upon an oxide, but it will be merely 
dissolved. 
The sulphates are an important class of salts. The greater number 
of them are soluble in water, and the solutions are rendered turbid by 
solutions of baryta. They are all decomposed at a red heat by char- 
coal, and most of them are thus converted into sulphurets ; carbonic, 
acid, and carbonic oxide, being at the same time evolved. 
In the neutral sulphates the proportion of oxygen in the acid is to 
that in the base as 3 to 1. Thus sulphate of soda is composed of 32 
soda containing 8 of oxygen, combined with 40 of sulphuric acid con- 
taining 24 of oxygen. 
528. Action of Sulphuretted Hydrogen.—It seems doubtful whether 
any of the metals combine with sulphuretted hydrogen. It unites with 
several of their oxides, and forms hydrosulphurctted oxides. Many of 
these compounds are insoluble, and may be formed by adding a solution 
of sulphuretted hydrogen, or of hydrosulphuret of ammonia, to solu- 
tions of the respective metallic salts. Sometimes, however, a decom- 
position is effected in these cases, both of the sulphuretted hydrogen 
and of the oxide, and a metallic sulphuret is formed, the hydrogen com- 
bining with the oxygen of the oxide to form water, and the sulphur 
uniting to the metal. In a few cases the metallic oxide is reduced. 
The following table shows the effect of sulphuretted hydrogen and of 
hydrosulphuret of ammonia upon solutions of several of the metals, as 
lar as colour of the precipitate is concerned. 
Sulphates. 
Sulphuretted 
hydrogen. OF THE METALS. 
METAL. 
SOLUTION. 
SULPHURETTED 
HYDROGEN. 
HYDROSULPHURET 
OF AMMONIA. 
MANGANESE 
Neutral protomuriate 
No precipitate 
Copious ochre yellow 
IRON 
Neutral protosulphate 1 
Blackish and small ini 
quantity 
Black and abundant 
Ditto 
Permuriate 
Abundant black 
Black 
ZINC 
Muriate 
A little opalescent and] 
then milky 
Straw colour and copi- 
ous 
TIN 
Acid protomuriate 
Brown 
Deep orange 
Ditto j 
Acid permuriate 
At first 0, then yellow i 
and copious 
Apple green 
CADMIUM . . . 
Muriate 
Y ellow 
Yellow 
COPPER . . . . 
Protomuriate 
Deep brown 
Brown 
Ditto | 
Pernitrate 
Black 
Brown and black 
LEAD | 
Muriate and nitrate 1 
Black 
Brown and black 
ANTIMONY . ,| 
Tartrate of antimony and i 
potassa 
Deep orange-red 
Bright orange 
BISMUTH . • •[ 
Tartrate of bismuth andl 
potassa 
Deep brown 
Deep brown 
COBALT . . . .| 
Muriate 
0 but blackish 
Copious black 
URANIUM . . .| 
Sulphate 
Brown 
Blackish brown 
TITANIUM . .| 
Acid muriate 
° i 
Black 
Ditto j 
Neutral sulphate 
0 ! 
Green 
CERIUM . . . .| | 
TELLURIUM .j 
ARSENIC . . .| 
White oxide 
i 
Ditto | 
Arsenic acid 
i 
NICKEL . . . ,| 
Sulphate 
Brown 
Black 
MERCURY . .| 
Acid nitrate 
Black, then gray, and] 
black by excess of test | 
Black by excess of test 
Ditto | 
Acid pernitrate 
Ditto 
Ditto 
Ditto | 
Corrosive sublimate 
Brown by excess of test I 
Ditto 
RHODIUM , . .| J | 
PALLADIUM .| 
SILVER . . . ,| 
Nitrate 
Black, and films of re-| D 
duced silver 1 Brown 
GOLD | 
Muriate | Black, and reduced gold J Yellow 
PLATINUM . .j 
Nitrate | Deep brown | Pale brown 
Colour of pre- 
cipitates by 
sulphurated 
hydrogen. 
529. Action of Phosphorus.—Phosphorus combines with the greater 
number of the metals, forming a series of metallicphosphurets. There 
are two methods of forming them; either by heating a mixture of1 
phosphorus and the metal, or projecting phosphorus upon the metal 
previously heated to redness ; or by heating a mixture of the metal 
or its oxide, with phosphoric acid and charcoal. These phosphurets 
have a metallic lustre ; if they contain a difficultly fusible metal, they 
are more fusible than the metal they contain ; if an easy fusible metal, 
Action of phos- 
phorus. 172 
general properties 
less so. They are mostly cfystallizable, and totally or partially de- 
composable at a high temperature. The greater number of the phos- 
phurets have only been examined by Pelletier,—Annales de Chiinie, 
Tom i. et xiii. and Memoires et Observations de Chiinie. 
530. The metallic phosphates may be formed either by dissolving the 
oxides in phosphoric acid, or by adding a solution of phosphoric acid, 
or of an alcaline phosphate, to solutions of those metals which form inso- 
luble or difficultly soluble phosphates. The greater number of the 
phosphates are decomposed by ignition with charcoal ; and those con- 
taining volatile oxides are volatilized at high temperatures. 
In the neutral phospates the quantity of oxygen in the acid is to 
that in the base as 2 to 1. Thus phosphate of soda consists of 32 
soda containing 8 oxygen, and 28 phosphoric acid containing 16 of 
oxygen. 
531. When phosphorus is introduced into the solutions of those me- 
t . s which have but a feeble attraction for oxygen, it reduces them to 
the metallic state. Thus gold, silver, and platinum are thrown down 
by immersing a stick of phosphorus into their respective solutions. 
532. Action of Carbon.-—Carbon unites to very few of the metals, 
and of the metallic carburets, one only is of importance, namely car- 
buret of iron, or steel.. 
533. Carbonic acid unites with the greater number of the metallic ox- 
ides and forms Carbonates, of which the distinctive characters have al- 
ready been noticed ; many of them are of difficult solubility, and may 
be formed by adding an alcaline carbonate to the metallic solution. Of 
the carbonates some are entirely, and others only partially decompos- 
ed at a red heat. Carbonate of magnesia, for instance,' loses the 
whole of its carbonic acid at a red heat ; carbonate of potassa retains 
it; and bi-carbonate of potassa loses one-half and passes into the state 
of carbonate. 
534. The action of Boron upon the metals has not been investigated, 
though it appears from the experiments of Descotils, (Recherches Physi- 
co-chymiques de M. M. Gay-Lussac et Thenard) to be capable of unit- 
ing to platinum and iron. These compounds may be called borurets. 
The metallic borates are numerous but mostly unimportant. Many of 
them are insoluble and easily formed by adding solution of boracic acid, 
or a soluble borate to the metallic solution. 
535. Action of the Metals upon each other.—The metals may for the 
'most part be combined with each other, forming a very important class 
of compounds, the metallic alloys. Various processes are adopted in 
the formation of alloys depending upon the nature of the metal6. 
Many are prepared by simply fusing the two metals in a covered cru- 
cible ; but if there be a considerable difference in the specitic gravity 
of the metals, the heavier will often subside, and the lower part of the 
bar or ingot, will differ in composition from the upper; this may be 
prevented by agitating the alloy till it solidifies. Mr. Hatchett found 
that when an alloy of gold and copper was cast into bars, the moulds 
being placed perpendicularly, the upper part of the bar contained more 
copper than the lower.—Phil. Trans. 1803. 
Where one of the metals is very volatile, it should generally be ad- 
ded to the other after its fusion ; and if both metals be volatile, they 
may be sometimes united by distilling them together. 
It has been a question whether alloys are to be considered as com- 
Phosphates. 
Action of Car- 
bon. 
Carbonates. 
Action of Bo- 
ron. 
Action of me- 
tals upon each 
other. OF THE METALS. 
173 
pounds, or as mere mixtures ; but their properties leave little doubt 
of their being real compounds, and in some cases they are found to 
unite in definite proportions only ; and it is probable that all the alloys 
contain a definite compound of the two metals. 
536. The principal characters of the alloys are the following : 
i. We observe a change in the ductility, malleability, hardness, and 
Golour. Malleability and ductility, are usually impaired, and often in' 
a remarkable degree : thus gold and lead, and gold and tin, form a brittle 
alloy. The alloy of copper and gold is harder than either of its com- 
ponent parts ; and a minute quantity of arsenic added to copper, ren- 
ders it white. 
ii. The specific gravity of an alloy is rarely the mean of its compo- 
nent parts, in some cases an increase, in others a diminution of density 
having taken place, as shown by the following Table from Thenard.— 
Traite de Chimie, Vol. i. p. 394. 
Characters of 
alloys. 
Alloys possessed of greater specific gravity than Alloys having a specific gravity inferior tp the 
the mean of their components. mean of their components. 
Gold and Zinc 
Tin 
Bismuth 
Antimony 
Cobalt 
Silver and Zinc 
Lead 
Tin 
Bismuth 
Antimony 
Copper and Zinc 
Tin 
Palladium 
Bismuth 
Antimony 
Lead and Bismuth 
Antimony 
Platinum & Molybdenum 
Palladium and Bismuth 
Gold and Silver 
Iron 
Lead 
Copper 
Iridium 
Nickel 
Silver and Copper 
Copper and Lead 
Iron and Bismuth 
Antimony 
Lead 
Tin apd Lead 
Palladium 
Antimony 
Nickel and Arsenic 
Zinc and Antimony 
Specific gravi- 
ty of alloys 
compared with 
their constitu- 
ents. 
iii. The fusibility of an alloy is generally greater than that of its 
components. Thus platinum, which is infusible in our common fur- 
naces, forms, when combined with arsenic, a very fusible alloy; and 
an alloy of certain proportions of lead, tin, and bismuth is fusible at 
212®, a temperature several degrees below the melting point of its 
most fusible constituent. 
#iv. Alloys are generally more oxidizable than their constituents 
taken singly ; a property which is, perhaps, partly referable to the 
formation of an electrical combination. Where an alloy consists of 
two metals, the one easily and the other difficultly oxidizable, it maybe 
decomposed by exposing it to the action of heat and air, the former 
metal being converted into an oxide ; its last portions, however, are 
often not easily separated, being protected by combination with the 
least oxidable metal. An alloy of three parts of lead and one of tin 
is infinitely more oxidizable than either of its components, and easily 
burns at a dull red heat. 
v. The action of acids on alloys may generally be anticipated by a 
knowledge of their effects upon the constituent metals; but if a solu-. 
hie metal be alloyed with an insoluble one, the former is often protect-1 
ed by the latter from the action of an acid. Thus, silver alloyed with 
Action of 
acids on at 
loys. 174 
GENERAL PROPERTIES 
a large quantity of gold, resists the action of nitric acid in consequence 
of the insolubility of the latter metal in that acid ; and, in order to ren- 
der it soluble, it is requisite that it should be made to form about a 
fourth part of the alloy, in which case the nitric acid extracts it, and 
leaves the gold in an insoluble film or powder. 
537. Various classifications of the metals have been adopted by che- 
mical authors ; some dependent upon their physical, others upon their 
chemical properties. The former can scarcely be considered as adapt- 
ed to chemical inquiry, and the latter involve numerous difficulties in 
consequence of the gradual transition of metals of one class into those 
of another. I shall consider the metals in the order in which they are 
set down in the following Table, and which is nearly that of their re- 
spective attractions for oxygen. 
1 Potassium 
2 Sodium 
3 Lithium 
4 Calcium 
5 Barium 
6 Strontium 
7 Magnesium 
23 Arsenic 
24 Molybdenum 
25 Chromium 
26 Tungsten 
27 Columbium 
8 Manganese 
9 Iron 
10 Zinc 
11 Tin 
12 Cadmium , 
28 Nickel 
29 Mercury 
30 Osmium 
31 Iridium 
32 Rhodium 
33 Palladium 
34 Silver 
35 Gold # 
36 Platinum 
Uletals in the 
order of their 
attractions for 
oxygen. 
13 Copper 
14 Lead 
15 Antimony" 
16 Bismuth 
17 Cobalt 
18 Uranium 
19 Titanium 
20 Cerium 
21 Tellurium 
22 Selenium 
37 Silicium 
38 Alumium 
39 Zirconium 
40 Glucium 
41 Yttrium 
42 Thorinum 
Of these metals the first seven produce alcaline oxides which are 
very difficult of reduction ; and they rapidly decompose water at all 
temperatures, a character which announces their powerful attraction 
for oxygen ; the next five decompose water when their temperature is 
raised to redness : the ten following do not decompose water at a red 
heat; nor do the next five, which produce acids by uniting to oxygen. 
The oxides of these twenty-seven metals are not reducible by heat 
alone, though some of them, when heated, give out a portion of oxy- 
gen. The nine metals which next follow, osmium excepted, have a 
comparatively feeble attraction for oxygen ; and when their oxides are 
heated, they are reduced to the metallic The last six metals are 
placed in the list from analogy ; they are only known in the state 6f 
oxides, which have not hithe.rto been reduced. POTASSIUM. 
Section I. Potassium. 
538. This metal was discovered in 1807 by Sir Humphry Davy,— 
(Philos. Trans. 1808). He obtained it by submitting caustic potassa, 
or potash, to the action of Voltaic electricity : the metal was slowly 
evolved at the negative pole. By this process, however, it could only 
be procured in very minute quantities ; and various other methods 
have been devised, of which the best is that described by Gay-Lussac 
and Thenard. (Recherches Physico-chymiques.) It is as follows : 
539. A sound and perfectly clean gun-barrel is bent, as shown-in the 
annexed sketch. It is then covered with an infusible lute between the 
Process for ob- 
taining- it. 
the letters o and e (fig.l.) and the interior of the luted part is filled 
with clean iron turnings. Pieces of fused potassa are then loosely placed 
in the barrel between e and c. a a is a copper tube and small receiv- 
er, which are adapted to the extremity o, and to each other by grind- 
ing. This apparatus is next transferred to the furnace, arranged as 
shown in fig. 2, x and t representing two glass tubes dipping into mer- 
cury. The furnace is supplied with air by a good double bellows en- 
tering at b, and a small wire basket g, is suspended below the space e c. 
The part of the barrel in the furnace is now cautiously raised to a 
white heat, and the escape of air by the tube x shews that all is tight. 
Some burning charcoal is then put at the end e, of the cage g, which 
causes a portion of potassa to liquefy and fall into the low part of the 
barrel upon the iron. Hydrogen gas instantly escapes by the tube x, 
and attention must now be had to keep the copper tubes a a cool, by 
laying wet cloths upon them. When the evolution of gas ceases, fresh 
charcoal is placed under the potassa, and so on till the whole has passed 
down ; if too much potassa be suffered to fall at once, the extrication 
of gas at x will be very violent, which should be avoided. If the space' 
between a and o should become stopped by potassium, gas will issue by 
the tube t (which must always be under a greater pressure of quick- 176 
PROTOXIDE OF POTASSIUM. 
silver than the tube x), and it may be fused by applying hot charcoal t* 
the tube, when the gas will again appear at x and cease at t. When 
the operation is concluded, the tubes x and t are removed, and corks 
quickly applied to the holes ; and when the apparatus is cool, the bar- 
rel is carefully removed from the furnace, and a little naphtha suffered 
to run through it. The potassium is found in globules in the tube and 
receiver a a, and considerable portions often lodge at o. The suc- 
cess of this operation is certain, if the heat has been sufficient; but 
the barrel, if not very carefully covered with lute, is apt to melt, and 
much, if not the whole of the product is lost. 
540. Potassium is a white metal of great lustre. It instantly tar- 
nishes by exposure to air. It is ductile, and of the consistency of soft 
wax. Its specific gravity is 0.85. At 150° it enters into perfect fu- 
sion ; and at a bright red heat rises in vapour. At 32° it is a hard and 
brittle solid. If heated in air it burns with a brilliant white flame. It 
is an excellent conductor of electricity and of heat. 
541. Potassium and Oxygen.—When potassium is thrown into water 
it instantly takes fire ; hydrogen gas is evolved, and oxide of potassium 
or potassa, is found dissolved in the water. The quantity of hydrogen 
evolved in this experiment becomes the indicator of the proportion of 
oxygen which has been transferred to the metal; 100 parts of potas- 
sium are thus found to absorb 20 of oxygen ; and if this be considered 
a protoxide, then 20 : 100 : : 8 : 40,—so that 40 will be the number 
representing potassium, and 40 P. -f- 8 O. = 48 will represent dry 
oxide of potassium. 
542. Potassa, in the state it is usually met with in laboratories, con- 
tains a considerable portion of water, from which it may be freed by 
the action of iron at high temperatures, and there always remains in 
the barrel, after the above experiment, a large portion of dry potassa. 
It is a hard grey substance, which, by water, is slowly converted into 
the hydrated oxide, or caustic potash, which may be obtained by eva- 
poration. This substance, after exposure to a red heat, is white 
and very soluble in water; it may be considered as a compound of 1 
proportional of protoxide of potassium = 48 ■+• 1 proportional of water 
9 and its number = 57. 
543. Peroxide of Potassium.—If the metal be heated in considerable 
excess of oxygen, it burns with intense heat and light, and an orange-co- 
loured substance is obtained, which consists of 40 potassium+24 oxy- 
gen=64. This peroxide of potassium, when put into water, efferves- 
ces, oxygen is given off, and a solution of the hydrated protoxide is 
obtained. Peroxide of potassium is also formed by passing oxygen 
over potassa heated to redness. 
544. The hydrated protoxide or caustic-potash, is procured in our 
laboratories by decomposing its carbonate by lime. The best process 
consists in boiling in a clean iron vessel, carbonate of potassa, (obtain- 
ed by calcining tartar) with half its weight of pure quick lime, in water. 
The ley is strained through clean linen, concentrated by evaporation, 
again strained, and set by in a well-stopped bottle till it admits of being 
decanted clear from the sediment. The clear solution is to be evapo- 
rated to dryness. It is often cast into sticks for the use of surgeons, 
who employ it as a caustic, and in this state it generally contains some 
peroxide, and therefore evolves oxygen when dissolved in water. It 
is the potassa fusa of the London Pharmacopoeia. It may be further 
Character. 
Combination 
with oxygen. 
Peroihle. 
Mo'le of pro- 
curing caustic 
potassa. CHLORATE OF POTASSA. 
177 
purified by the action of alcohol, which dissolves the pure hydrate and 
leaves earthy and other impurities ; the alcohol is then driven off by 
heat. In this case the alcohol is always in some measure acted upon 
by the potassa, and a portion of carbonaceous matter that 
it should be allowed to remain as short a time as possible combined 
with the alcali. Having obtained the dry caustic alcali by lime, it may 
be boiled in a silver basin with highly rectified alcohol for a few 
minutes, and then set by in a stopped phial; when the impurities are 
deposited, the alcoholic solution may be poured oft’ and rapidly evapo- 
rated to dryness in a silver basin as before : the heat may then be rais- 
ed so as to fuse the potassa, which, on cooling, should be broken up 
and preserved in well-closed phials. 
Hydrate of Potassa thus purified is white, very acrid and corrosive, 
and at a bright red heat evaporates in the form of white acrid smoke. 
It quickly absorbs moisture and carbonic acid from the air, and at 60° 
one part of water dissolves two. It may be crystallized in octoedrons. 
It is highly alcaline, and being exclusively procured from vegetables 
was formerly called vegetable alcali. When touched with moist fingers( 
it has a soapy feel, in consequence of its action upon the cuticle. In 
the fused state it produces heat when dissolved in water ; but in its 
crystallized state it excites considerable cold, especially when mixed 
with snow. At a natural temperature of 30°, M. Lowitz found that 
equal weights of crystallized potassa and snow depressed the thermom- 
eter 45°.—Annales de Chimie, xxii. 
545. Chlorine and Potassium act very energetically on each other, 
and produce the white compound which has been called muriate of potash,' 
but which is a true chloride of potassium, consisting of 40 P. -f- 36 Ch. 
When potassium is heated in gaseous muriatic acid, this compound is 
formed, and hydrogen is evolved. It dissolves without decomposition 
in three parts of water at 60°. It crystallizes in cubes ; its taste is sa- 
line and bitter. In old pharmacy it was called salt of Sylvius ; also, re- 
generated sea-salt. 
546. Chlorate of Potassa is formed by passing chlorine through a 
solution of potassa. Chloride of potassium is one of the results, the 
other is a salt in brilliant rhomboidal tables (formerly called oxymu- 
riate of potash), the chlorate. 
This salt is prepared, upon the large scale, by charging one or two 
Wolfe’s bottles with solution of carbonate of potassa, and passing 
chlorine slowly through it: the gas is absorbed, and the liquor effer- 
vesces chiefly from the escape of carbonic acid ; when this has ceased, 
the liquor may be put aside in a cold dark place for about 24 hours, 
when it will be found to have deposited a considerable* portion of the 
crystallized chlorate, which may be taken out, drained, and purified 
by solution in hot water, which, during cooling again, deposits the salt 
in white crystalline scales. The liquor is generally of a pinkish hue, 
from the presence of manganese. 
The taste of this salt is cooling and austere. When triturated it 
appears phosphorescent. When exposed to a dull red heat it decrepi- 
tates, fuses, and gives out oxygen, and chloride of potassium remains. 
It is soluble in 18 parts of cold and 2.5 of boiling water. It acts very 
energetically upon many inflammables and triturated with sulphur, 
phosphorus, and charcoal, produces inflammation and explosion. A 
mixture of three parts of this chlorate with one of sulphur, detonates 
Character. 
Chloride. Oxychlorate op potassa. 
loudly when struck upon an anvil with a hammer, and even sometimes 
explodes spontaneously ; hence it should not be kept ready mixed. 
Chlorate of potassa was proposed by Berthollet as a substitute for 
nitre m gunpowder. The attempt was made at Essone in 1788 ; but, 
as might have been expected, no sooner was the mixture of the 
chlorate with the sulphur and charcoal submitted to trituration, than it 
exploded with violence, and proved fatal to several people. With 
phosphorus the detonation is dangerously violent. These phenomena 
depend upon the decomposition of the chloric acid. The action of 
sulphuric acid upon chlorate of potassa has already been adverted to 
(217). If, instead of distilling the yellow mixture of the acid and 
chlorate with the caution there described, it be heated to about 150°, 
it suddenly explodes. The theory of the production of chloric oxide 
appears to be as follows : the sulphuric acid expels one proportional 
of oxygen from the chlorate, and the potassium absorbs one proportion- 
al to produce potassa, which gives rise to sulphate of potassa; the 
remaining four proportionals of oxygen and one of chlorine form the 
oxide of chlorine. 
When sulphuric acid is poured upon mixtures of this salt and com- 
bustibles, instant ignition ensues in consequence of the evolution of 
oxide of chlorine, and when sulphuric or nitric acids are poured upon 
similar mixtures under water by means of a long funnel, inflammation 
also ensues. 
A few grains of chlorate of potassa put into a tea-spoonful of muri- 
atic acid, and then diluted with water, form an extemporaneous bleach- 
ing liquor. 
Chlorate of Potassa consists of one proportional of chloric acid and 
one of potassa, or 76 C. A. -f- 48 P. Its ultimate components, there- 
fore, are 
6 proportionals of oxygen .... 
5 in the acid and 1 in the alcali 
II 
CO 
1 
proportional of chlorine.... 
= 36 
1 
% potassium. . . 
= 40 
“ 124 
547. Oxychlorate of Potassa may be formed by moistening one part 
of chlorate of potassa with three of sulphuric acid, and subsequently 
carefully heating the mass till it becomes white : in this state it consists 
of bisulphate and oxychlorate of potassa, which may be separated by 
solution and crystallization, the former being much more soluble in cold 
water than the latter salt. 
Oxychlorate of potassa does not change vegetable colours, nor is it 
altered by exposure to air. It requires rather more than 50 parts of 
water at 60° for its solution. It is insoluble in alcohol. It crystallizes 
in elongated octoedrons. When mixed with its own weight of sulphuric 
acid, and distilled at 280°, solution of oxychloric acid passes over. It 
may be decomposed by exposure to a temperature of 412°. Oxygen 
is given off, and chloride of potassium remains in the retort. This salt 
is thus found to consist of one proportional of oxychloric acid = 92 -J- 
©ne proportional potassa = 48, and its representative number is there- 
fore = 140. 5*48. Iodide of Potassium. Iodine and potassium act upon each other 
very energetically, and a crystalline compound is obtained, white and 
fusible. The hydriodic acid and potassa produce a similar compound, 
jr 549. When iodine is put into solution of potassa, the results are 
iodate of potassa and iodide of potassium : the latter may be removed 
by alcohol. 
Iodate of Potassa, is a white difficultly soluble salt, which at a red heat, 
gives out oxygen, and is converted into iodide of potassium.—Gay- 
Lussac, Ann. de Chim., xci. 
550. Potassium and Hydrogen.—When potassium is heated in hydro- 
gen, it absorbs a portion of the gas, and produces a grey and highly 
inflammable hydruret. When hydrogen and potassium are passed to- 
gether through a white hot tube, the gas dissolves the metal, and pro- 
duces a spontaneously inflammable potassiuretted hydrogen gas. Both 
these compounds are usually formed during the operation for obtaining 
potassium by the gun-barrel. 
551. Nitrate of Potassa—Nitre—-Saltpetre. This salt is an abundant 
natural product, and is principally brought to this country from the 
East Indies, where it is produced by lixiviation from certain soils. 
The rough nitre imported from the East Indies is in broken crystals 
©f a brown colour, and more or less deliquescent: exclusive of other 
impurities, it often contains a very considerable proportion of common 
salt, which re-acting upon the nitre, induces the production of nitrate 
of soda and chloride of potassium. 
In Germany and France it is artificially produced in what are termed 
nitre-beds. Thenard {Traite deChemie Elementaire, Tom. ii., p. 511.) 
has described the French process at length. It consists in lixiviating 
old plaster rubbish, which when rich in nitre, affords about five per 
cent. Refuse animal and vegetable matter which has putrified in con- 
tact with calcareous soils produces nitrate of lime, which affords nitre 
by mixture with subcarbonate of potassa. In the same way it is abun- 
dantly produced in some parts of Spain. Exudations containing salt- 
petre are not uncommon upon new walls, where it appears to arise 
from the decomposition of animal matter contained in the mortar. It 
was long ago shown by Glauber, that a vault plastered over with a 
mixture of lime, wood-ashes, and cows’ dung, soon becomes covered 
with efflorescent nitre, and that after some months, the materials yield, 
on lixiviation, a considerable proportion of that salt. 
Nitre crystallizes in six-sided prisms, usually terminated by dihedral 
summits ; it dissolves in 7 parts of water at 60°, and in its own weight 
at 212°. Its taste is cooling and peculiar. It consists of one propor- 
tional of acid = 54 -f- one proportional of potassa = 48. Or of 
NITRATE OF FOTASSA. 
6 proportionals of oxygen .... 
* | 48 
5 
in the acid and 1 in the alcali . 
1 
proportional of nitrogen.... 
. 14 
1 
potassium . . . 
. 40 
102 
552. When exposed to a white heat, nitre is decomposed into oxy- 
gen, nitrogen, and dry potassa. It fuses at a heat below redness, and 
congeals on cooling into cakes called sal prunelle. 
If the temperature of nitre be so far increased as to allow a portion 
of oxygen to escape, the remaining salt, as Scheele first observed, re- 
mains neutral, and in this state it has been considered as foriping a nir 
trite of polassa. POTASSA AXD SULPHUR. 
Nitre is rapidly decomposed by charcoal at a red heat; and, if excess 
of charcoal be used, the results are carbonic oxide and acid, nitrogen, 
and subcarbonate of potassa, formerly called nitrum fixum, and white 
Jlux. 
The old chemists used to perform this detonation in retorts connect- 
ed with capacious receivers, which were generally blown to pieces ; 
sometimes they succeeded in obtaining a little acidulated water, which 
they called clyssus of nitre, and attributed to it wonderful medical vir- 
tues. 
When phosphorus is thrown UpoH nitre, and inflamed, a vivid com- 
bustion ensues, and a phosphate of potassa is formed. Sulphur 
sprinkled upon hot nitre burns and produces a mixture of sulphate and 
sulphite of potassa. This salt used formerly to be employed in medi- 
cine, under the name of Glaser's polychrest salt. Most of the metals, 
when in filings or powder, detonate and burn when thrown on red-hot 
nitre ; Some of the more inflammable metals produce in this way a con- 
siderable explosion. 
553. A mixture of three parts of nitre, two of dry subcarbonate of 
potassa, and one of sulphur, forms fulminating powder. If a little of 
this compound be heated upon a metallic plate, it blackens, fuses, and 
explodes with much violence, in consequence of the rapid action of the 
sulphur upon the nitre. 
554. Gunpowder consists of a very intimate mixture of nitre, sulphur, 
and charcoal. The proportions vary. The following are those usual- 
ly employed : 
Common 
Gunpowder. 
Shdoting 
powder. 
Shooting 
powder. 
Miners’ 
powder. 
Saltpetre , 
. . 75.0 
78 
76 
65 
Charcoal . 
. 12.5 
12 
15 
15 
Sulphur . . 
. 12.5 
10 
9 
20 
l'he latter contains the smallest quantity of saltpetre, as it requires 
less quickness or strength. The ingredients arc perfectly mixed, mois- 
tened, beaten into a cake which is afterwards broken up, granulated, 
dried, and for the finest powder polished by attrition. The violence 
of the explosion of gunpowder depends upon the sudden production of 
gaseous matter, resulting from the action of the combustibles upon the 
nitre. Carbonic oxide, carbonic acid, nitrogen, and sulphurous acid, 
are the principal gaseous results ; and the solid residue consists of sub- 
carbonate, sulphate, and sulphuret of potassa, and charcoal.—Cruick- 
shanks, Nicholson’s Journal, iv. 
Gunpowder may, it is said, be inflamed by a violent blow ; if mixed 
with powdered glass, or any other harder substance, and struck with 
a heavy hammer upon an anvil, it almost always explodes. 
555. Potassium unites to Sulphur with the evolution of much heat and 
light, and forms a grey compound, which, when acted upon by water, 
produces sulphuretted hydrogen. It consists of 40 P. -f- 16 S. — 56. 
556. Potassa and Sulphur, when fused together, form a red sulphu- 
ret of potassa. (Liver of Sulphur.) Its taste is bitter and acrid. It is 
deliquescent and very soluble in water, forming a yellow solution of 
hydrosulphuret of potassa. The action of the sulphuret of potassa on 
water is complicated, and has been variously explained. By some this is EI-SULPHATE OF POTASSA. 
181 
considered as a compound of potassium and sulphur ; in which case, when 
acted upon by water, hydrogen is imparted to the sulphur, and oxygen 
to the potassium; and a sulphuret of potassa with excess of sulphur 
(or sulphuretted sulphuret of potassa) is formed. If we consider the 
sulphuret as consisting of potassa and sulphur, then, the oxygen as well 
as the hydrogen of the water, must be transferred to the sulphur, and 
sulphuric and sulphurous acid, and sulphuretted hydrogen, wrould be 
formed ; and generally when the solutions of the livers of sulphur are 
examined, sulphate and sulphite of the alcali, are found. On the whole 
however, it appears most probable, that when sulphur and the alcalies 
are fused together at a high temperature, the latter undergo decompo- 
sition, and that sulphurets of their metallic bases are actually formed. 
Vauquelin, .flnn. de Chim. 
557. Hyposulphite of Potassa is formed by decomposing hydrosulphu- 
ret of potassa by sulphurous acid and evaporating to a pellicle, when 
it forms acicular crystals, of a cooling bitter taste, and deliquescent. 
558. Sulphite of Potassa is formed by passing sulphurous acid into a 
solution of potassa, and evaporating out of the contact of air. Rhom- 
boidal plates are obtained, white, of a sulphurous taste, and very solu- 
ble. By exposure to air, they pass into sulphate of potassa. 
559. Sulphate of Potassa is the result of several chemical operations 
carried on upon a large scale in the processes of the arts. It may be 
formed directly by saturating sulphuric acid by potassa. It is the sal 
de duohus of the old chemists : the potassa sulphas of the London Phar- 
macopoeia. Its taste is bitter. It crystallizes in short six-sided prisms, 
terminated by six-sided pyramids. The body of the prism is often 
wanting and the triangular-faced dodecaedron results. This salt dis- 
solves in 16 parts of cold, and 5 of boiling water, and in consequence 
of its difficult solubility, it is thrown down in a white granular powder, 
when sulphuric acid is added to a moderately strong solution of potas- 
sa. Exposed to a red heat it melts, but is not decomposed. Heated 
with charcoal it produces sulphuret of potassa. It consits of 
1 proportional of acid 
— 40 
1 alcali 
= 48 
"88 
560. Bi-sulphate or Supersulphate of Potassa is formed by adding sul- 
phuric acid to a hot solution of sulphate of potassa, or by boiling suh- 
phate of potassa with sulphuric acid. The first crystals which form 
are in delicate needles of an acid taste, soluble in 2 parts of water at 
60°, and consist of 
2 proportionals of acid . . 
= 80 
1 potassa 
= 48 
128 
Bi-sulphate of Potassa is also formed in the distillation of equal 
parts of nitre and sulphuric acid : nitric acid passes over, and a resi- 
duary bi-sulphate of potassa is produced, commonly known under the 
name of sal enixum. It is the arcanum duplicatum, or panacea Holsati- 
ca of old pharmaceutists. It is used for cleansing coin and other 
works in metal; and has a place in the London Pharmacopoeia. 
The following diagram will illustrate the formation of this salt, and 
of liquid nitric acid, in the distillation of two proportionals of sulphuric 
acid with one of nitre : S«BPHOSPHATE OP1 potassA, 
1 Liquid Nitric Acid = 72. 
2 Water 
= 18. 
1 Dry 
Nitric Acid 
= 54.0 
2 Liquid Sul- 
phuric Acid 
= 98. 
1 Nitrate of 
Potassa = 
102. 
2 Di'y 
Sulphuric Acid 
= 80. 
J Potassa 
= 48. 
561. Ammonia-Sulphate of Potassa is a triple salt formed by adding 
ammonia to bisulphate of potassa. It crystallizes in brilliant plates of 
a bitter taste.—Link. CrelVs Annals, 1796. 
562. Phosphuret of Potassium is a brown compound, which rapidly 
decomposes water, producing phosphuretted hydrogen gas, and hydro- 
phosphuret of potassa. It is formed by cautiously heating potassium 
with phosphorus out of the contact of air. 
563. Hypophosphite of Potassa has been examined by Dulong. It 
is very deliquescent, and soluble in water and alcohol nearly in all pro- 
portions. When heated it evolves phosphuretted hydrogen and phos- 
phorus, and is converted into phosphate of potassa.—Annales de Chim. 
et Phys., ii. 142. 
564. Phosphite of Potassa is a soluble deliquescent uncrystallizable 
salt, not hitherto accurately examined. 
565. Phosphate of Potassa. is a soluble difficultly crystallizable salt. 
It may be obtained by careful evaporation, in four-sided prisms, and 
©ctoedrons. It contains 
1 Bisulphate of Potassa = 128. 
1 proportional of potassa 
1 phosphoric acid 
. = 48 
. = 28 
76 
566. Subphosphate of Potassa.—When phosphate of potassa is fused 
in a platinum crucible with potassa it is converted into subphosphate of 
potassa, which is insoluble in cold, and very difficultly soluble in hot 
water. It is fusible before the blow-pipe, yielding a globule opaque 
when cold, but transparent whilst in fusion. The theoretical compo- 
position of this salt is 
2 proportionals of potassa 
= 96 
1 —... —- acid 
= 28 
124 CARBONATE OF FOTAS-SA. 
567. Superphosphate or Biphosphate of potassa is formed by dissolv- 
ing the neutral phosphate in phosphoric acid and evaporating till crys- 
tals are obtained, which are prismatic and very soluble. 
568. Potassa and Carbonic Acid.—These bodies combine in two pro- 
portions, forming the carbonate and the bicarbonate of potassa, com- 
pounds which have been long used and known under various names— 
such as fixed nitre, salt of tartar, salt of wormwood, vegetable alcali, fyc. 
Their composition was first ascertained by Black. Bergman, in 1774, 
described their most essential properties.—Opuscula, Vol. i. p. 13. 
569. Carbonate of Potassa is a salt of great importance in many arts 
and manufactures, and is known in commerce in different states of pu- 
rity, under the names of wood-ash, pot-ash, and pearl-ash. It is tne 
subcarbonate of potassa of the London Pharmacopoeia. 
It may be obtained directly by passing carbonic acid into a solution 
of potassa, evaporating to dryness, and exposing the dry mass to a red 
heat; or indirectly by burning tartar, whence the name salt of tartar 
has been applied to it. 
This salt is fusible without decomposition, at a red heat: it is very so- 
luble in water, and deliquesces by exposure to air, forming a dense so- 
lution, once called oil of tartar per deliquium. Its taste is alcaline, and 
it renders vegetable blues green. It consists of 
1 proportional acid 
= 22 
1 potassa 
= 48 
70 
The great consumption of this article in various manufactures is ex- 
clusively supplied by the combustion of vegetables, and consequently 
its production is almost limited to those countries which require clear- 
ing of timber, or where there are vast natural forests. The English 
market is chiefly supplied from North America. If any vegetable grow- 
ing in a soil not impregnated with sea-salt be burned, its ashes will be 
found alcaline from the presence of carbonate of potassa. If the ashes 
be submitted to heat, so as to burn away the carbonaceous matter en- 
tirely, they become a white mass, generally termed pearl-ash. 
The pearl-ash of commerce, contains a variety of impurities which 
render it of variable value. In general, its purity may be judged of 
by its easy solubility in water, two parts of which should entirely dis- 
solve one part of the salt ; the residue, if any, consists of impurities. 
The quantity of nitric acid of a given density, requisite to saturate a 
given weight, may also be resorted to as a criterion of its purity. 100 
parts of nitric acid, specific gravity 1.36, will saturate 70 parts of dry 
carbonate of potassa, which are equivalent to 48 parts of pure potassa. 
Upon the means of ascertaining the quantity of real alcali in the differ- 
ent articles of commerce, some useful observations will be found in Dr. 
■Henry’s Elements of Chemistry, ii. 512. According to Vauquelin (An- 
nales de Chirnie, Vol. xl.) the principal varieties of this substance used 
in commerce, contain the following ingredients :— FOTASSTffM. 
Potash. 
Sulphate 
of 
potash. 
Muriate 
of 
potash. 
Insolu- 
ble 
residue. 
Carbonic 
Acid and 
water. 
TOTAL. 
Potash of Russia 
772 
65 
5 
56 
254 
1152 
America . . . . 
857 
154 
20 
2 
119 
1152 
American Pearl-ash . . . 
754 
80 
4 
6 
308 
1152 
Potash of Treves 
720 
165 
44 
24 
199 
1152 
Dantzic .... 
603 
152 
14 
79 
304 
1152 
Vosges . . . . 
444 
148 
510 
34 
304 
1440 
A saturated solution of carbonate of potassa in water contains about 
48 per cent, of the salt, and has a specific gravity of 1.5. 
570. Bi-carbonate of Potassa is formed by passing a current of car- 
bonic acid into a solution of the subcarbonate. By evaporation crys- 
tals are obtained in the form of four-sided prisms, with dihedral sum- 
mits. Their taste is only slightly alcaline, and they require for solu- 
tion four parts of water, at 60°. Exposed to a red heat, carbonic acid 
is evolved, and carbonate of potassa remains. This bi-carbonate con- 
sists of 
2 proportionals of carbonic acid 
— 44 
1 potassa, 
= 48 
92 
In its crystalline form it contains water equal to one proportional\ 
and, therefore, consists of 
92 carbonate 
9 water 
101 
In the London Pharmacopoeia the more expensive method of obtain- 
ing this salt by the action of carbonate of ammonia on carbonate of 
potassa is resorted to. 
The following proportions may be used for the preparation of bi- 
carbonate of potassa upon the large scale : 100 lbs. of purified car- 
bonate of potassa are dissolved in 17 gallons »of water, which, when 
saturated with carbonic acid, yields from 28 to 30 lbs. of crystallized 
bi-carbonate ; 50 lbs. of carbonate of potassa are then added to the 
mother liquor, with a sufficient quantity of water to make up 17 gallons, 
and the operation repeated. 
The subcarbonate and carbonate of potassa, are both decomposed by 
lime, which deprives them of carbonic acid ; hence the use of that 
earth in the process for obtaining pure potassa. 
571. Potassium heated in cyanogen absorbs the gas, and produces a 
grey cyanuret of potassium, which by the action of water becomes CHLORIDE OF SODIUM. 
185 
kydrocyanate of potassa. This salt speedily decomposes and becomes 
converted into carbonic acid and ammonia. 
572. Borate of Potassa is a salt which has been scarcely examined ; 
it may be prepared by boiling boracic acid in solution of potassa, or by 
exposing a mixture of boracic acid and nitre to a bright red heat; it 
furnishes by solution and evaporation quadrangular prisms, permanent 
in the air. 
573. The salts of potassium are soluble in water, and afford no pre- 
cipitates with pure or carbonated alcalis. They produce a precipitate 
in muriate of platinum, which is a triple compound of potassa, oxide of 
platinum, and muriatic acid. They are not changed by sulphuretted 
hydrogen, nor by ferro-prussiate of potassa. Added to sulphate of 
alumina, they enable it to crystallize, so as to form alum. 
Section II. Sodium. 
574. Sodium, discovered by Sir H. Davy in 1808, is obtained from 
soda by an operation analogous to that for procuring potassium from 
potassa (539). It is soft, malleable, and easily sectile. Its specific 
gravity is 0.97. In colour it resembles lead. It fuses at about 190°, 
and is volatile at a white heat. It burns when heated in contact with 
air, and requires the same cautions to preserve it as potassium. 
575. Sodium and Oxygen.—When sodium is thrown upon water, it 
produces violent action, but the metal does not in general inflame ; 
hydrogen is evolved, and a solution of soda is procured. By the 
quantity of hydrogen evolved, we learn that soda (protoxide of sodium) 
consists of about 75 sodium and 25 oxygen per cent.; and, if it be 
considered as the protoxide, the number representing the metal will be 
24, and soda will consist of 24 S. -f- 8 0., and be represented by 32. 
576. By heating sodium in oxygen, it burns vividly, and an orange- 
coloured peroxide is formed, consisting of 24 S. -{- 12 0., and which, 
by the action of water, evolves oxygen, and produces a solution of the 
protoxide. 
577. Soda, as it usually occurs in the laboratories, is obtained from 
the carbonate, by the action of lime and alcohol, as described under the 
head potassa (544). It consists of 32 protoxide of sodium -f- 9 water, 
and is represented by 41. When soda is exposed to air, it soon becomes 
covered with an efflorescence of carbonate of soda. Its colour is grey- 
ish white, and it requires a red heat for fusion. 
578. Soda is distinguished from potassa, by forming an efflorescent 
paste when exposed to the atmosphere ; potassa under the same cir- 
cumstances deliquesces. If excess of tartaric acid be added to a solution 
of soda there is no precipitation ; but in solution of potassa it occasions 
a deposit of a number of minute crystals. Solution of soda occasions 
no precipitate when added to solution of muriate of platinum. Solu- 
tion of potassa occasions a yellow precipitate in solution of platinum. 
In combination with acids it produces a perfectly distinct class of salt. 
579. Chloride of Sodium.—Sodium, when heated in chlorine, burns 
and produces a white compound, of a pure saline flavour, soluble in 186 
24 parts of water at 60°, and forming cubic crystals. It has all the 
properties of common salt or muriate of soda, and consists of 
1UDATE OK SODA. 
1 proportional of chlorine = 36 
sodium = 24 
60 
This compound is decomposed, when heated with potassium : so- 
dium and chloride of potassium are the results. 
When soda is heated in chlorine, oxygen is evolved; wrhen heated 
in muriatic acid, water is formed, and in both cases chloride of sodium 
is the product. 
580. Common salt exists abundantly in nature, both as a solid fossil 
and dissolved in water. Immense masses of it are found in Cheshire, 
where it is known under the name of rock salt. 
581. When heated, chloride of sodium falls into pieces with a 
crackling noise, or decrepitates. At a red heat it fuses without under- 
going any decomposition, and on cooling concretes into a hard white 
mass. It is scarcely more soluble in boiling than in cold water, and 
nearly insoluble in alcohol. When pure it does not alter by exposure 
to air; obtained by slow or spontaneous evaporation, it crystallizes in 
solid cubes; but when procured, as is usually the case at a boiling 
heat, by removing its crystals from the surface of its solution wdnlst 
evaporating, it exhibits the form of a hollow quadrangular pyramid. 
A concise account of the different methods of manufacturing salt will 
be found in Aikin’s Dictionary.—Art. Muriate of Soda. 
582. Chloride of sodium is decomposed by moist carbonate of 
potassa, and chloride of potassium and carbonate of soda are the re- 
sults. In the common process for obtaining muriatic acid it is decom- 
posed by sulphuric acid. (250). In this decomposition there is a 
transfer of the oxygen contained in the water of the sulphuric acid to 
the sodium of the salt, the chlorine of which combines with the hy- 
drogen of the water to produce muriatic acid gas. The oxide of so- 
dium unites with the dry sulphuric acid to produce sulphate of soda. 
(590). 
Common salt is of most extensive use as a preservative of food, and 
as a condiment. Glauber first obtained muriatic acid from it, and the 
existence of soda in it was first shown by Duhamel. 
583. Chlorate of Soda was procured by Mr. Chenevix {Phil. Trans. 
1802), by the same process as chlorate of potassa, but not possessing 
less solubility than chloride of sodium, the two substances are difficult- 
ly separable. Vauquelin obtained it by saturating chloric acid with 
soda. Its crystals resemble those of chlorate of potassa, its taste is 
also nearly similar. 
584. Sodium and Iodine act upon each other with the same pheno- 
mena as potassium, and an iodide of sodium is obtained. The hydrio- 
dic acid and soda produce a similar compound. It is deliquescent, and 
its solution yields quadrangular crystals. 
585. Iodate of Soda is made by dissolving iodine in solution of soda : 
a white compound forms, which is the iodate with a portion of hydrio- 
date of soda ; the latter may be removed by alcohol. Iodate of soda 
forms small prismatic tufted crystals, which, when heated, afford oxy- 
gen and iodide of sodium.—Gay-Lussac, Annalesde Chimie, xci. PHOSPHATE OF SODA. 
586. Nitrate of Soda crystallizes in rhombs, soluble in three parts 
of water at 60°, and in less than its weight at 212°. It has a cool 
sharp flavour, and is somewhat deliquescent. It consists of 32 soda -f- 
54 nitric acid. It is often found in crude nitre, resulting apparently 
from the decomposition of common salt. It is the cubic nitre of old,, 
writers. 
587. Sulphuret of Sodium and of Soda. See Potassium. (556). 
The sulphurets exhibit nearly similar properties. 
588. Hyposulphite of Soda is formed as hyposulphite of potassa. 
(557.) It is difficultly crystallizable, deliquescent, of an intensely bit- 
ter taste, and insoluble in alcohol. Its aqueous solution readily dis- 
solves moist chloride of silver. 
589. Sulphite of Soda is crystallizable in transparent four and six- 
sided prisms, soluble in four parts of water at 60°. It consists of 32 
soda -f 32 sulphurous acid. The crystals contain twelve proportion- 
als of water = 108. 
590. Sulphate of Soda—Glauber’s Salt—Sal mirabile—is abundantly 
produced in the manufacture of muriatic acid, by the action of sulphu- 
ric acid upon common salt. 
Common salt consists of 24 Sodium 36 chlorine. Sulphuric acid 
consists of 40 dry acid -{- 9 water. The water of the acid, consisting 
of 1 hydrogen -f- 8 oxygen, is decomposed. Its hydrogen is transfer- 
ed to the chlorine to produce gaseous muriatic acid (1 H. -j- 36 C.= 
37 Mur. A.), and its oxygen unites to the sodium, forming dry soda 
(8 Ox. -J- 24 S. = 32 soda). The 40 dry acid, unite to the 32 soda, 
to produce sulphate of soda, which will be represented by the number 72. 
591. Sulphate of soda crystallizes from its aqueous solution in large 
four-sided prisms, transparent, and efflorescent, when exposed to air. 
They consist of 72 dry sulphate -{- 90 water exposed to dry air, the 
crystals part with about 50 per cent, of water. 
The taste of sulphate of soda is saline and bitter : it is soluble in ra- 
ther less than three times its weight of water at 60°. When exposed 
to heat it undergoes watery fusion, that is, it melts in its own water of 
crystallization ; when this has evaporated it fuses. 
592. Sulphate of soda is sometimes decomposed for the purpose of 
obtaining soda, by igniting it with chalk and charcoal, or with iron and 
charcoal. (Of these processes a full account is given in Aikin’s Dic- 
tionary, Art. Muriate of Soda.) Its principal use is in Pharmacy. 
593. Bi-sulphate of Soda is obtained by adding sulphuric acid to a 
hot solution of sulphate of soda. It crystallizes in Rhomboids soluble 
in twice their weight of water at 60°. This salt consists of 72 sulphate 
of soda + 40 sulphuric acid = 112.—Crell’s Annals, 1796. 
594. Ammonio-sulphate of Soda is a triple salt, formed by saturating 
the bi-sulphate with ammonia.—Crell’s Annals, 1796, I. 
595. Phosphite of Soda has not been examined. Hypophosphite of 
Soda is very soluble both in alcohol and water.—Annales de Chim. et 
Phys. ii. 142. 
596. Phosphate of Soda crystallizes in rhomboidal prisms soluble in 
four parts of water at 60°, and efflorescing when exposed. It has a 
pure saline taste. It consists of 
32 soda 
28 phosphoric acid 
60 CARBONATE OF SODA. 
The crj'stals contain about 60 per cent, of water. This salt is usual- 
ly obtained for pharmaceutical purposes by saturating the impure phos- 
phoric acid, obtained from calcined bones by sulphuric acid, (See 
Phosphorus) with carbonate of soda: the liquor is filtered, evaporated, 
and set aside to crystallize. It was introduced into pharmacy by Dr. 
Pearson ; it is the sal perlatum of some old writers. 
When heated, phosphate of soda fuses and boils up, and having lost 
its water of crystallization, it runs into a clear glass, which becomes 
opaque on cooling. If a globule be heated before the blow-pipe it as- 
sumes the dodecaedral figure as it cools. 
597. Treated with sulphuric acid, phosphate of soda is only partly 
decomposed, a bi-phosphate of Soda being formed, which is more solu- 
ble than, and not so easily crystallizable as the phosphate. 
598. Amrnonio-phosphate of Soda exists in human urine, whence it 
was procured by the early chemists under the names of microcosmic and 
fusible salt. When exposed to heat the ammonia is expelled, and a bi- 
phospate of soda remains : it appears to consist of two proportionals of 
phosphoric acid = 56 ; one of soda = 32, and one of ammonia = 17. 
—Fourcroy, Annales de Chimie, vii. 183. 
599. Carbonate of Soda is chiefly obtained by the combustion of ma- 
rine plants, the ashes of which afford, by lixiviation, the impure alcali 
called soda. Two kinds of rough soda occur in the market ; barilla, 
and kelp; besides which, some native carbonate of soda is also imported. 
Barilla is the semifused ash of the salsola soda, which is largely culti- 
vated upon the Mediterranean shore of Spain, in the vicinity of Alicant. 
Kelp consists of the ashes of sea weeds, which are collected upon 
many of the rocky coasts of Britain, and burned in kilns, or merely in 
excavations made in the ground and surrounded by stones. It seldom 
contains more than 5 per cent, of carbonated alcali, and about 24 tons 
of sea weed are required to produce one ton of kelp. The best pro- 
duce is from the hardest/wci, such as the serratus, digitatus, nodosus, and 
vesiculosus. (Mac Culloch’s Western Islands, Vol. i., p. 122.) The 
rough alcali is contaminated by common salt, and other impurities, from 
which it may be separated by solution in a small portion of water, fil- 
trating the solution, and evaporating it at a low heat: the common salt 
may be skimmed off as its crystals form upon the surface. 
600. The primitive crystalline form of carbonate of soda is an octoe- 
dron, with a rhombic base ; the solid angles of the summit are always 
wanting, being replaced by planes parallel to the base, and thus pre- 
senting a solid with 10 surfaces. It is soluble in twice its weight of 
water at 60°. Its taste is strongly alcaline, and it greens vegetable 
blues. It consists of 
32 soda 
22 carbonic acid. 
54 
Its crystals contain seven proportionals of water = 63, which ma}f be 
expelled by heat. They effloresce by exposure to air. This salt is the 
Sodce-Subcarbonas of the Pharmacopoeia. 
In the analysis of barilla and kelp, to ascertain the relative propor- 
tion of soda, it may be useful to know that 100 parts of dilute nitric SULPHURIC ACIIl. 
acid, specific gravity 1.36, will saturate 50 parts of dry carbonate of 
soda, which are equivalent to about 29 of pure soda. 
601. Bi-carbonate of Soda is formed by passing carbonic acid through 
the solution of the subcarbonate. By evaporation a crystalline mass is 
obtained. This salt consists of 
32 
44 
soda 
carbonic acid 
76 
The bi-carbonate of soda has a very slightly alcaline taste, and it is 
much less soluble in water than the sub-carbonate. 
602. This salt, as well as the bi-carbonate of potassa, may be ob- 
tained by treating their respective carbonates with carbonate of am- 
monia ; pure ammonia is evolved and bi-carbonates are formed.—See 
London Pharmacopoeia. 
In the manufacture of this bi-carbonate for the purpose of com- 
merce, 160 lbs. of carbonate may be dissolved in 13 gallons of water, 
and carbonic acid thrown into the solution in a proper apparatus. 
The bi-carbonate falls as it forms to the amount of about 50 lbs., and 
being separated from the solution may be conveniently dried by pres- 
sure in an hydraulic press, and subsequent exposure to heat not ex- 
ceeding 100°. A fresh portion of carbonate is dissolved in the mother 
liquor, and the operation repeated as before. 
603. A mixture of the carbonates of soda occurs native in great 
abundance in Africa, in the province of Gahena, near Fezzan. The 
natives call it Trona. It has been analyzed by Mr. R. Phillips, who 
considers it as a compound intermediate between the carbonate and bi- 
carbonate, composed of 3 proportionals of acid and 2 of base, or 1 
soda + \\ acid ; hence he terms it a sesqui-carhonate of Soda.—Quar- 
terly Journal, \ii., p. 298. 
A very productive soda-lake also exists in South America in Mara- 
caybo, one of the provinces of Venezuela.—Quarterly Journal, i. p. 
188. 
604. Subborate of Soda—Borax.—This salt, which has been very 
long known, is imported from India in an impure state, under the name 
of Tincal, which, when purified, is called Borax. It crystallizes in 
irregular hexaedral prisms, slightly efflorescent. Its taste is alcaline 
and styptic. It is soluble in 20 parts of water at 60°, and in six parts 
of boiling water. When heated it loses water of crystallization, and 
becomes a porous friable mass, called calcined borax. It consists, ac- 
cording to Bergman, of 
34 
17 
49 
acid 
soda 
water 
100 
Sulphuric acid decomposes this salt, producing sulphate of soda 
and boracic acid. (Chap. IV. § vi.) It has a place in the Pharmaco- 
poeia, and is sometimes used as a flux. 
605. The salts of sodium arc soluble in water. They are not pre- 190 
CHLORIDE OF LITHIUM. 
cipitated either by pure or carbonated alcalis, or hydrosulphuret of 
ammonia, or ferro-prussiate of potassa ; they produce no precipitate 
in solution of muriate of platinum, and do not convert sulphate of 
alumina into octoedral alum. 
606. Potassium and sodium form an alloy, which, if composed of 
one part of potassium and three of sodium, remains fluid at 32°. 
Equal parts of the metals form a brittle crystallizable alloy. 
Section III. Lithium. 
607. In the analysis of a mineral, called petalite, M. Arfwedson 
discovered about three per cent, of an alcaline substance, which was at 
first supposed to be soda ; but, finding that it required for its neutrali- 
zation a much larger quantity of acid than soda, he was led to doubt 
its identity with that alcali, and the further prosecution of his inqui- 
ries fully demonstrated that it possessed peculiar properties. The 
mineral called triphane, or spodumene, also affords the same substance, 
to which the term lithia, deduced from its lapideous original, has been 
applied. It has also been detected in a few other minerals. 
The following is the mode of obtaining lithia from the above substan- 
ces :—Reduce the mineral to a fine powder, and fuse it with about half 
its weight of potassa ; dissolve the fused mass in muriatic acid, filter, 
and evaporate to dryness ; digest the dry mass in alcohol ; the only 
substance present, soluble in that liquid, is the muriate of lithia, which 
is taken up, and by a second solution and evaporation is obtained pure. 
It may be decomposed by digesting carbonate of silver in its aqueous 
solution, by which a carbonate of lithia is formed, decomposible by 
lime, in the way of the other alcaline carbonates. 
608. When lithia is submitted to the action of the Voltaic pile, it is 
decomposed with the same phenomena as potassa and soda ; a brilliant 
white and highly combustible metallic substance is separated, which 
may be called lithium , the term lithia being applied to its oxide. 
The properties of this metal have not hitherto been investigated, 
in consequence of the difficulty of procuring any quantity of its oxide. 
609. Pure lithia is very soluble in water, and its solution tastes acrid 
like the other fixed alcalis. It acts powerfully on vegetable blues, 
converting them to green. It is very sparingly soluble in alcohol. 
Direct experiments upon the composition of lithia are yet wanting. 
By calculation from the composition of the sulphate, as analyzed by 
Vauquelin, it would appear to contain about 55.2 lithium -f- 44.8 oxy- 
gen.* 
610. Chloride of Lithium, obtained by evaporating the muriate to 
dryness, and fusing it, is a white semitransparent substance. It evi- 
dently differs from the chlorides of potassium and sodium, in being ex- 
tremely deliquescent; in being soluble in alcohol; in being decompos- 
oxygen lithia 
* 44.8 : 55.2 p44.8 —100 : : 8 (atom oxygen) : 17.8 (the atom lithia which agrees with 
the composition of the sulphate. CARBONATE OF LITHIA. 
191 
ed when strongly heated in the open air, when it loses chlorine, absorbs 
oxygen, and becomes highly alcaline ; in being very difficultly crystal- 
lizable ; and in tinging the flame of alcohol of a red colour. 
611. Iodide of Lithium.—The action of iodine, of hydriodic acid, 
and of iodic acid, on lithia has not been examined. 
612. Nitrate of Lithia is a very soluble deliquescent salt, fusible and 
decomposed by heat; its taste is cooling; it crystallizes in rhomboids. 
613. Sulphuret of Lithium.—The action of sulphur on lithium and 
lithia appears analogous to its action on potassium and potassa, but the 
compounds have not been precisely examined. 
614. Sulphate of Lithia crystallizes in small rectangular prisms, 
perfectly white, and possessed of much lustre. Their taste is saline, 
and their solubility intermediate between that of sulphate of potassa 
and sulphate of soda. The crystals contain no water, and fuse at a 
heat below redness. Their solution occasions no change in solution of 
platinum, nor in tartaric acid. They consist of 
Sulphuric acid .... 
or 
40 
Lithia 
or 
17.8 
100 
or 
57.8 
615. Phosphate of Liihia has been examined by Dr. Gmelin : it 
may be obtained by adding phosphoric acid to sulphate of lithia ; no 
precipitate is at first formed, but on adding excess of ammonia, an in- 
soluble phosphate of lithia falls. This property enables us to separate 
lithia from potassa and soda. The phosphate of lithia may be decom- 
posed by dissolving it in acetic acid and adding acetate of lead : acetate 
of lithia remains in solution. 
616. Carbonate of Lithia.—When a strong solution of carbonate of 
potassa is added to sulphate of lithia, a white precipitate of carbonate 
of lithia is formed. It requires about 100 parts of water at 60° for 
its solution. It is fu ible, alcaline, effervesces with acids, and absorbs 
carbonic acid from the air. Lithia and its carbonate, when heated upon 
platinum, act upon that metal. 
617. If we assume from Vauquelin’s corrected analysis of the sul- 
phate, that lithia contains 45 per cent, of oxygen and 55 of lithium, 
and that it is a protoxide, then 45 : 55 : : 8 : 9.77. So that the num- 
ber 9.8 might be assumed as the representative number of lithium ; 
and oxide of lithium, or lithia, would contain— 
Lithium 
Chloride of Lithium . . . 
. 9.8 4* Oxygen 
. 9.8 + Chlorine .... 
8 — 17.8 
36 — 45,8 
Nitrate of Lithia—Lithia . 
. 17.8 -j- Nitric acid . . . 
54 = 71.8 
Sulphate 
. 17.8 Sulphuric acid . 
40 = 57.8 
Carbonate 
. 17.8 4* Carbonic acid 
22 = 39.8 
N. B. It is probable that 10 is the number for lithium instead of 
9.8, for 10 is a multiple of 0.125 (the atom hydrogen) which is not the 
case with 9.8. 192 
oxygen- 
Section IV. Calcium. 
618. When lime is electrized negatively in contact with mercury, 
an amalgam is obtained, which, by distillation, affords a white metal. 
It has been called calcium, and when exposed to air, and gently heated, 
it burns and produces the oxide of calcium, or lime. 
Lime appears to consist of 20 parts of this metallic base united to 8 
parts of oxygen, so that its representative number will be = 28. 
619. The combinations of lime are very abundant natural products, 
and of these the native carbonate which, more or less pure, constitutes 
the different kinds of marble, chalk, and limestone, and which is also 
the leading hardening principle of shell, coral, fyc., may be considered 
as the most important. 
Lime may be obtained in a state of considerable purity by exposing 
powdered white marble to a white heat, which expels the carbonic acid. 
To obtain absolutely pure lime, white marble maybe dissolved in dilute 
muriatic acid, a little ammonia added to the solution, and filtered : car- 
bonate of ammonia is then added, and the precipitate dried, washed, 
and exposed to a white heat. Its colour is light grey ; it is acrid and 
caustic and converts vegetable blues to green; its specific gravity is 
2.3 ; it is very difficult of fusion, but remarkably promotes the fusion 
of most other earthy bodies, and is therefore used in several metallur- 
gic processes as a cheap and powerful flux. When quite pure it can 
only be fused in very minute particles by the oxygen blow-pipe, or by 
the Voltaic flame. It is an essential ingredient in mortar and other 
cements used in building. Exposed to air it becomes white by the 
absorption of water and a little carbonic acid. 
620. When a small quantity of water is poured upon lime, there is 
a great rise of temperature resulting from the solidification of a portion 
of the water, and a white powder is obtained, called slacked lime, which 
is a hydrate, and which appears to consist of one proportional of water 
= 9 4* one proportional of lime = 28 = 37 hydrate. 
Lime may be obtained in a crystalline form by placing lime water un- 
der the receiver of an air-pump, containing another vessel of sulphuric 
acid. The water is thus slowly evaporated, and imperfect six-sided 
crystals of hydrate of lime are formed.—Gay-Lussag, Annales de Chimie 
et Phys., i. 334. 
At the temperature of 60°, 750 parts of water are required for the 
solution of one part of lime. 
621. Lime-water is limpid and colourless ; its taste is nauseous, 
acrid, and alcaline, and it converts vegetable blues to green. It is usu- 
ally prepared by pouring warm water upon powdered lime, and allow- 
ing the mixture to cool in a close vessel: the clear part is then decanted 
from the remaining undissolved portion of lime. When lime-water is 
exposed to the air, a pellicle of carbonate of lime forms upon its sur- 
face, which, if broken, is succeeded by others, until the whole of the 
lime is thus separated in the form of an insoluble carbonate. Lime- 
water is used in medicine as an antacid. 
622. When oxygen is passed over heated lime, it is absorbed, and a 
portion of peroxide of calcium is formed. A hydrated peroxide of cal- NITRATE OF LIME. 
cium is thrown down, according to M. Thenard, when lime-water is 
dropped into oxygenated water. 
623. Chloride of Calcium is produced by heating lime in chlorine, in 
which case oxygen is evolved ; or by evaporating muriate of lime, ob- 
tained by dissolving carbonate of lime in muriatic acid, to dryness, and 
exposing the dry mass to a red heat in close vessels. It consists of 20 
calcium -f- 36 chlorine = 56. This compound has a strong attraction 
for water ; it deliquesces when exposed to air, and becomes what used 
to be called oil of lime. It is difficultly crystallizable from its aqueous 
solutions ; with care, however, it may be obtained in six-sided prisms, 
consisting of the chloride combined with water. It is most readily 
crystallized by exposing its solution to the temperature of 32°. Its 
taste is bitter and acrid ; one part of water at 60° dissolves four parts 
of the chloride. Its solubility, however, is greatly influenced by tem- 
perature, for at 32® one part of water will not dissolve more than two 
of the salt, and at 212° it takes up nearly any quantity. It is copiously 
soluble in alcohol, and much heat is evolved during the solution. When 
fused it acquires a phosphorescent property, as was first observed by 
Homberg, and hence termed Homberg’s phosphorus. It is abundantly 
produced in the manufacture of carbonate of ammonia, from the de- 
composition of muriate of ammonia by lime, and hence has sometimes 
been called fixed sal ammoniac. The production of cold by mixing 
muriate of lime with snow has already been adverted to. (81.) Chlo- 
ride of lime absorbs ammoniacal gas in considerable quantities. (Fa- 
raday, Journal of Science, Vol. v. p. 74.) In its fused state this com- 
pound is very useful for drying certain gaseous bodies, but where the 
quantity of the gas is to be ascertained, its powers of absorption in cer- 
tain cases must not be overlooked. 
Pelletier has stated, that if carbonic acid be passed through a solution 
of muriate of lime, the whole becomes a hard solid mass. If sulphuric 
acid be poured into a strong solution of muriate of lime, the whole con- 
geals into a solid inass of sulphate of lime. 
624. A substance called Oxymuriate of Lime is abundantly employed 
as a bleaching material, and manufactured by passing chlorine into 
leaden chambers containing hydrate of lime in fine powrder, by which 
the gas is copiously absorbed. Dr. Thomson has show n this to be a 
compound of chlorine and lime ; when heated it gives off a large quan- 
tity of oxygen, and a chloride of calcium results. This shows the su- 
perior attraction of calcium for chlorine compared to oxygen, the 
latter being expelled from the lime. 
625. Chlorate of Lime is a very soluble deliquescent salt of a sharp 
bitterish taste. It is most easily produced by dissolving carbonate of 
lime in chloric acid. Exposed to heat, oxygen is evolved, and a chlo- 
ride formed. 
626. Iodate of Lime is difficultly crystallizable in small quadrangular 
prisms. Hydriodate of Lime is very deliquescent; whe% dried it be- 
comes iodide of calcium, a white fusible compound. 
627. Nitrate of Lime is a deliquescent salt, soluble in 4 parts of 
water at 60°. It is found in old plaster and mortar, from the washings MYrOSUtPHITES OF SODA. 
of which, nitre is procured by the addition of carbonate of potassa. ft 
is composed of 
34.94 
Lime 
.... 28 
65.OG 
Nitric acid 
.... 54 
100 
82 
The production of this salt in artificial nitre-beds has already been 
adverted to. (551.) It may be crystallized in six-sided prisms. It is 
soluble in alcohol. When exposed to a moderate heat it undergoes 
watery fusion : the water then evaporates, and the salt fuses ; on cool- 
ing it concretes into a semi-transparent phosphorescent substance, call - 
ed from the discoverer of this property, Baldwin’s phosphorus. At a 
red heat it is decomposed ; its acid is dissipated, and pure lime remains. 
It contains in its crystallized state about 25 per cent, of w'ater, and may 
hence be considered as composed of 
1 proportional dry nitrate . . 
. 82 
3 —— water 
. 27 
109 
628. Sulphuret of Lime is formed by heating lime with sulphur. It 
is soluble in water with the same phenomena as sulphuret of potassa. 
629. According to Mr. Herschel, crystallized hydrosulphuret of lime 
is formed when three parts of slacked lime and one of sulphur are 
boiled in twenty parts of water, and the solution allowed to cool upon 
the sediment: he dried the crystals by exposure to the absorbent 
power of a large surface of sulphuric acid, placed under an exhausted 
receiver. Their form is that of quadrilateral prisms with dihedral 
summits. They are sparingly soluble in cold water, the solution hav- 
ing a yellow colour and an acrid, bitter, and sulphurous taste. They 
consist of two proportionals of lime, two of sulphur, one of hydrogen, 
and four of water.—Edinburgh Philosophical Journal, i. p. 11, 4'c. 
630. When sulphurous acid is ground in a mortar with the above 
crystals its smell disappears, and wrhen filtered it is found to be a solu- 
tion of hyposulphite of lime. By passing sulphurous acid through an 
aqueous solution of sulphuret of lime, the same product is obtained : 
and if the solution be filtered and evaporated, at a temperature not 
exceeding 140°, it furnishes crystals : the temperature of ebullition 
decomposes it. The crystals are little altered by air, very soluble in 
water, and insoluble in alcohol. They consist, according to Mr. Her- 
schel, of 
Lime 
21.71 
Acid 
Water 
100 
631. The hyposulphites of soda, potassa, and ammonia, of baryta, 
and of strontia, may be formed by passing sulphurous acid through the 
aqueous solutions of their sulphurets. SULPHATE OF LIME. 
195 
632. Sulphite of Lime is formed by passing sulphurous acid into a 
mixture of lime and warm water. It is a white powder, soluble by 
excess of sulphurous acid, and then separating in prismatic crystals, of 
difficult solubility, efflorescent, and passing into sulphate of lime by 
exposure to air. 
633. Sulphate of Lime occurs native in selenite, gypsum, and plaster- 
stone. It is easily formed artificially, and then affords silky crystals 
soluble in 350 parts of water. When these, or the native crystallized 
sulphate are exposed to a red heat, they lose water, and fall into a white 
powder (plaster of Paris), which, made into a paste with water, soon 
solidifies. Dry sulphate of lime consists of 
28 
40 
lime 
sulph. acid 
68 
Crystalline sulphate of lime contains two proportionals of water, and 
is consequently represented by 68 -f- 13 = 86. As sulphate of lime 
is more soluble in water than pure lime, sulphuric acid affords no pre- 
cipitate when added to lime-water. Nearly all spring and river water 
contains this salt, and in those waters which are called hard it is abun- 
dant. It gives to them a slightly nauseous taste. At a very high tem- 
perature sulphate of lime is fusible, but it suffers no decomposition ; 
heated with charcoal it is converted into a sulphuret. It dissolves 
without decomposition in dilute nitric and muriatic acids, and separates 
from these solutions when concentrated in long silky or transparent 
crystals. It is decomposed by the alcaline carbonates. 
634. Native Sxdphate of Lime occurs in various forms. The crys- 
tallized variety is usually called selenite; the fibrous and earthy, gyp- 
sum; and the granular or massive, alabaster. The primitive form of 
selenite is a rhomboidal prism of 113° 8' and 66° 52'. The crystals 
are commonly transparent, and of various colours ; it is softer than 
native carbonate of lime, and yields very easily to the nail. It is sel- 
dom found in veins, but generally disseminated in argillaceous strata. 
It occurs in Cumberland at Alston, and in Oxfordshire at Shotover Hill, 
where it is often accompanied by shells and pyrites, and appears to 
have resulted from their mutual decomposition. A beautiful fibrous 
variety is found in Derbyshire, applicable to ornamental purposes. 
Massive and granular gypsum is found in this country accompanying 
the salt-deposits in Cheshire. It abounds at Montmartre, near Paris, 
and contains organic remains ; sometimes it forms entire hills. In the 
Tyrolese, Swiss, and Italian Alps, it is found upon the primitive rocks, 
often of the purest white, especially at Montier, near Montblanc, and 
near the summit of Mount Cenis. It is turned by the lathe, and sculp- 
tured into a variety of beautiful forms, more especially by the Floren- 
tine artists. 
635. There is a variety of sulphate of lime, which has been called 
anhydrous gypsum, or anhydrite, in reference to its containing no water. 
It is harder than selenite, and sometimes contains common salt, and is 
then called muriacite. It is rarely crystallized, generally massive and 
lamellar, and susceptible of division into rectangular prisms. It has 
been found in Derbyshire and Nottinghamshire of a pale blue tint; BI-PHOSPHATE OF LIML. 
sometimes it is pink or reddish, and often white. It has been found at 
Vulpino, in Italy, and hence called Vulpinite. The statuaries of Ber- 
gamo and Milan employ it, and artists know it by the name of Marbrc 
di Bergamo. A compound of sulphate of lime and sulphate of soda is 
found in the salt-mines of New Castile, which mineralogists have de- 
scribed under the name of Glauberite. 
636. Phosphuret of Lime.—By passing phosphorus over red-hot 
lime, a brown compound is produced, which rapidly decomposes water 
with the evolution of phosphuretted hydrogen gas. Hydrophosphuret 
and hypo-phosphite of lime are also formed. 
The best process for obtaining this phosphuret is the following : se- 
lect a green glass, or porcelain tube, closed at one end, and about 18 
inches long, and one inch diameter, and carefully cover it with a clay 
lute containing a very little borax. Put an ounce of phosphorus bro- 
ken into small pieces into the lower end, and fill it up with pieces of 
clean quicklime, about the size of large peas : place it in an inclined 
position in a furnace, so that the end containing the phosphorus may 
protrude, while the upper part of the tube is heating to redness ; then 
slowly draw the cool part into the fire, by which the phosphorus will 
be volatilized, and passing into the red-hot lime, convert a portion of 
it into phosphuret. Care should be taken that no considerable portion 
of phosphorus escapes and burns away at the open end of the tube, 
which, after the process, should be corked and suffered to cool. Its 
contents may then be shaken upon a sheet of paper, and the brown 
pieces picked out and carefully preserved in a well stopped phial ; the 
white pieces, or those which are only pale brown, must be rejected. 
This compound, though called phosphuret of lime, is probably a phos- 
phuret of calcium. 
637. Neither the Phosphite nor Hypophosphite of Lime have been 
particularly examined. 
638. Phosphate of Lime exsits abundantly in the bones of animals ; 
it is also found in the mineral world. It may be formed artificially, by 
mixing solutions of phosphate of soda and muriate of lime. It is insi- 
pid and insoluble in water, but dissolves in dilute nitric and muriatic 
acid without decomposition, and is precipitated unaltered by caustic 
ammonia. It is decomposed by sulphuric acid, and thus the phospho- 
ric acid for the production of phosphorus is usually procured. (See 
Phosphorus, Chap. IV., Sect, iv.) It consists of 
28 lime 
28 phosphoric acid 
56 
At. a very high temperature phosphate of lime fuses into an opaque 
white enamel. 
639. Bi-phosphate of Lime is formed by digesting the phosphate in 
phosphoric acid. On evaporation a white deliquescent uncrystalliza- 
ble mass is obtained, composed of one proportional of lime -j- two of 
phosphoric acid. 
640. The phosphoric glass described under the head phosphoric acid 
(Chap. IV ., Sect, iv.) is considered by Dr. Thomson as a definite com- 
pound, which he has termed quadriphosphate of lime.—System, ii. 460. CARBONATE OF LIME. 
197 
641. Native Phosphate of Lime has by some been regarded as a sub- 
phosphate, in which case it would be composed of two proportionals of 
of lime -p one phosphoric acid. This compound occurs crystallized 
and massive, and is known under the names of apatite, asparagus-stone, 
and phosphorite. The crystallized variety is found in Cornwall and 
Devonshire, of singular beauty. Its primitive form is a six-sided 
prism : it also occurs in volcanic products ; and, what is curious, the 
former is phosphorescent and the latter not. The massive variety is 
found in Bohemia and in Spain. 
642. Carbonate of Lime is the most abundant compound of this 
earth. When lime-water is exposed to air, it becomes covered with 
an insoluble film of carbonate of lime, and hence is an excellent test of 
the presence of carbonic acid. But excess of carbonic acid re-dis- 
solves the precipitate, producing a super-carbonate. Carbonate of 
lime is precipitated by the carbonated alealis from solutions of muriate, 
nitrate, and sulphate of lime. Exposed to a red heat the carbonic acid 
escapes, and quicklime is obtained. It consists of 
28 lime 
22 carbonic acid 
50 
643. Carbonate of lime occurs in nature in great abundance and in 
various forms. The primitive form of crystallized carbonate of lime, 
or calcareous spar, is an obtuse rhomboid of 105° 6' and 74° 55'. Its 
specific gravity is 2.7. It occurs in every kind of rock, and its secon- 
dary forms are more numerous than those of any other substance; 
sometimes it forms fine stalactites, of which some of the caverns of 
Derbyshire furnish magnificent specimens ; it is here deposited from 
its solution in water acidulated by the carbonic acid, and substances im- 
mersed in this water become incrusted by carbonate of lime, when the 
excess of acid flies off, as seen in the petrifying well of Matlock. A 
fibrous variety of carbonate of lime, called satin spar, is found in Cum- 
berland. 
Another variety, originally found in Arragon in Spain, has been term- 
ed Arragonite ; it occurs in six-sided crystals, of a reddish colour, and 
harder than the common carbonate. There is an acicular, or fibrous 
variety, found in France and Germany; and the white radiated sub- 
stance, improperly called Jlosferri, is also regarded as of the same spe- 
cies. Some varieties contain about 3 per cent, of strontia. 
All the varieties of marble and lime-stone consist essentially of car- 
bonate of lime ; of these, white granular lime-stone, or primitive mar- 
ble, is most esteemed ; there are, also, many coloured varieties of 
extreme beauty. It is distinguished from secondary lime-stone by the 
abscence of all organic remains, by its granularly foliated structure, 
and by its association with other primitive substances. 
The most celebrated statuary marble is that of Paros and of Mons 
Pentelicus, near Athens : of these, some of the finest specimens of an- 
cient sculpture are composed. The marble of Carrara, or Luni, on 
the eastern coast of the Gulf of Genoa, is also much esteemed ; it is 
milk-white, and less crystalline than the Parian. 
Many beautiful marbles for ornamental purposes are quarried in 
Derbyshire, and especially the black marble, called also Lucullite. COMPACT FLUOR. 
Westmoreland and Devonshire also afford beautiful varieties, and in 
Anglesea, a marble intermixed with green serpentine is found, little in- 
ferior in beauty to the verd antique. 
Among the inferior lime-stones, we enumerate many varieties, such 
as common marble ; bituminous lime-stone, abundant upon the Avon, 
near Bristol, and known under the name of swine-stone or stink-stone, 
from the peculiar smell which it affords when rubbed: Oolite or Roestone, 
of which the houses of Bath are built; and its variety, called Portland 
stone: Pisolite consists of small rounded masses, composed of con- 
centric layers, with a grain of sand always in the centre : and, lastly, 
chalk and marl. 
All these substances are more or less useful for ornamental purposes* 
or for building ; they afford quicklime when burned, and in that state 
are of great importance as manures, and as ingredients in the cements 
used forjbuilding. There is a|great variety of lime-stones used for burn- 
ning into quicklime, and, generally speaking, any of the varieties may 
be used which neither fuse nor crumble into powder at the tempera- 
ture required to expel the carbonic acid, which is a full red heat. 
644. Borate of Lime is a white tasteless powder of very difficult so- 
lubility in water. 
645. The salts of lime have the following properties :— 
Those which are soluble are not altered by pure ammonia, but they 
are decomposed by potassa and soda. They are also decomposed by 
the carbonates of potassa, soda, and ammonia, which produce precipi- 
tates of carbonate of lime. 
Oxalate of ammonia produces in their solutions a white insoluble 
precipitate of oxalate of lime, which, exposed to a red heat, affords 
pure lime. 
The insoluble salts of lime are decomposed by being boiled with 
carbonate of potassa, and afford carbonate of lime. 
646. Fluor Spar—Fluate of Lime.—These terms have been ap- 
plied to a body containing a peculiar principle which has not hitherto 
been obtained in an insulated state. 
It is a principle which probably belongs to the acidifying electro-ne- 
gative supporters of combustion, and which in fluor spar is, perhaps, 
united to calcium. It appears to be united with hydrogen in the fluoric 
or hydrofluoric acid. This supposed base has been called fluorine by 
Sir H. Davy ; and phtore (from (ptlogi<>?, destructive,) by M. Ampere. 
647. Fluor Spar is a mineral found in many parts of the world, but 
in great beauty and abundance in England, and especially in Derby- 
shire. Here it is commonly called Derbyshire spar, or by the miners 
of that county blue John. It is usually found in cubic crystals, which 
may easily be cleaved into octoedra, sometimes considered as its primi- 
tive form (27). Its colours are extremely various. Its specific gra- 
vity 3. It phosphoresces when exposed to a heat a little below red- 
ness. It generally occurs in veins ; in the Odin mine at Castleton in 
Derbyshire, it is found in detached masses, from an inch to more than 
a foot in thickness ; their structure is divergent, and the colours, which 
are various, disposed in concentric bands. It is the only variety which 
admits of being turned in the lathe into vases and other ornamental ar- 
ticles. 
Compact fluor is a scarce variety : the finest specimens come from 
the Hartz. A third variety is chlorophane, so called from the beautiful 
pale green light which it exhibits when heated. fluoboric acid. 
199 
The nature of the colouring matter of fluor Spar is not exactly un- 
derstood. It is liable to fade, and the blue varieties become red and 
brown by heat 
618. Hydrofluoric acid (hydrophtoric of Ampere) is procured by 
distilling a mixture of one part of the purest fluor spar in fine powder, 
with two of sulphuric acid ; the distillatory apparatus and receiver should 
be of lead or silver, for glass is instantly acted on ; the heat required is 
not considerable ; sulphate of lime remains in the retort, and a highly 
acrid and corrosive liquid passes over, which requires the assistance 
of ice for its condensation. 
This acid is colourless, of a very pungent smell, and extremely des- 
tructive. If applied to the skin it instantly kills the part, producing 
extreme pain, and extensive ulceration. At 80° it becomes gaseous ; 
it has never been frozen ; it produces white fumes when exposed to 
a moist air, and occasions a hissing noise when dropped into water. 
This acid acts upon potassium and sodium, and some other metals, 
with great energy ; hydrogen is evolved, and a peculiar compound, 
probably of the basis of the acid, and the metal, results. These com- 
pounds might be called fluorides. The principal hydrofluates, or 
fluates, have been examined by Gay-Lussac and Thenard. (Recherches 
Physico-chimiques.) They have not been analyzed, but if we adopt 
the number 17 as the representative of the acid, considering it as com- 
posed of 16 fluorine -j- 1 hydrogen, it is probable that they consist of 
one proportional of acid and one of base. 
619. Hydrofluate of Ammonia is not crystallizable, and when evapo- 
rated loses a portion of alcali and becomes sour ; when heated it rises in 
a dense white vapour. 
620. Hydrofluate of Potassa is a very soluble deliquescent, and dif- 
ficultly crystallizable salt, of a sharp taste. When heated it first loses 
its water of crystallization, then fuses (becoming fluoride of potassi- 
um ?) Sulphuric acid separates the hydrofluoric. 
621. Hydrofluate of Soda has less taste, and is less soluble than the 
preceding. When heated it decrepitates then fuses. It is permanent 
in the air, and separates from its solution in hot water, partly as a trans- 
parent pellicle and partly in crystals. 
622. When hydrofluoric acid is poured into solutions of the salts of 
lime, a white insoluble powder is thrown down, which resembles fluor 
spar in its chemical properties, and must therefore be considered as a 
fluoride of calcium. 
623. The hydrofluoric is the only acid that acts rapidly on glass, and 
cannot therefore be preserved in vessels of that material. If a plate 
of glass, covered with wax, having any device traced upon it by a blunt 
graver, be exposed to the fumes of this acid,.the glass presents the ap- 
pearance of having been etched, upon removing the wax.—See Silica* 
tedfluoric Acid, Sect, xxxvii. 
624. Fluoboric Acid.—This is probably a compound of fluorine with 
boron, and if regarded as consisting of one proportional of each of 
its components, its representative number will be 22, and it will con- 
tain 16 fluorine -f- 6 boron. It is gaseous, and may be obtained by 
heating in a glass retort twelve pai’ts of sulphuric acid, with a mixture 
of one part of fused boracic acid and two of fluor spar, reduced to 
a very fine powder. The gas must be received over mercury : 100 
cubical inches weigh 72.5 grains ; so that the specific gravity of fluo- HYDRATE OF BARYTA. 
boric acid compared with hydrogen, is 32.22, and with atmospheric aif, 
2.400 * It produces very copious fumes when suffered to escape into 
a moist atmosphere ; when acted upon by water, which dissolves 700 
times its volume, it affords a solution of hydrofluoric and boracic acids, 
whence it would seem that the hydrogen is transferred to the fluorine, 
and the oxygen to the boron. It acts with great energy on vegetable 
and animal bodies, depriving them of moisture and hydrogen. A piece 
of paper introduced into fluoboric gas becomes instantly charred. 
Potassium heated in this gas occasions the deposition of boron, and the 
production of fluoride of potassium, which by the action of water be- 
comes hydrofiuate of potassa. 
625. The fluoboric acid combines with different basis, and produces 
a class of salts which have been called fluoborates : of these the jiuo- 
borate of ammonia has been examined by Dr. John Davy. (Phil. Trans. 
1812.) It appears from his experiments that the fluoboric acid is ca- 
pable of condensing successively, one, two, and three volumes of am- 
monia. The first is a white solid, volatile in close vessels by the ap- 
plication of a gentle heat. The two other compounds are liquid, and 
when exposed to the atmosphere, lose ammonia and pass into the first. 
Section V. Barium. 
626. To obtain this metal, the earth baryta is negatively electrized 
in contact with mercury ; an amalgam is gradually formed, from which 
the mercury may be expelled by heat, and the metal barium remains ; 
appearing, according to Sir H. Davy, of a dark grey colour, and being 
more than twice as heavy as water. It greedily absorbs oxygen, and 
burns with a deep red light when gently heated, producing the oxide of 
barium. 
627. Oxide of Barium, Baryta, or Barya, is obtained by exposing 
the crystals of nitrate of baryta for some time to a bright red heat. 
It is of a grey colour, and very difficult of fusion ; it appears to con- 
sist of 70 barium + 8 oxygen, and is, consequently, represented by 
78. Its specific gravity is about 4, hence the name Baryta, as being 
the heaviest of the substances usually called earths. It eagerly ab- 
sorbs water, heat is evolved, and a white solid is formed, containing 
about 10 per cent, of water, which it retains at a red heat ; this is the 
hydrate of baryta, and may be considered as a compound of 1 propor- 
tional of baryta = 78 + 1 proportional of water = 9, and is, conse- 
quently, represented by 87. 
628. Hydrate of Baryta dissolves in boiling water, and, as the solu- 
tion cools, deposits flattened hexagonal prisms, which contain a larger 
quantity of water, and are easily fusible. According to Mr. Dalton, 
crystallized baryta consists of 1 proportional of baryta and 20 of wa- 
* Thomson in his late experiment (ann. Phi. vol. 16, 1820) makes the specific gravitj com- 
pared with atmospheric air = 2.3694, this would make the specific gravity about 34 times 
that of hydrogen. 201 
ter ; if it be exposed to air it effloresces into a white powder, containing 
1 proportional of baryta and 5 of water ; it appears therefore that 
there are three hydrates of baryta. (New Chem. Phil., ii. 522.) The 
aqueous solution, or baryta water, is limpid, colourless, and acts ener- 
getically on vegetable blues and yellows, changing them to green and 
red ; it rapidly absorbs carbonic acid, and deposits an insoluble carbo- 
nate of baryta. As baryta, like the alcalis, converts vegetable blues to 
green, and serves as an intermede between oil and water, it has been 
called an alcaline earth. It has a very acrid caustic taste, and is high- 
ly poisonous. It exists in two natural combinations only, namely, as 
sulphate and carbonate. 
629. When baryta is heated in oxygen, or when oxygen is passed 
over baryta heated to redness in a glass tube, the gas is absorbed and a 
grey compound is obtained, which is the peroxide of barium.; consist- 
ing of 
PEROXIDE OF BARIUM. 
1 proportional of barium 
2 oxygen 
= 70 
= 16 
86 
630. By dissolving peroxide of barium in muriatic acid, and preci 
pitating by sulphuric acid, M. Thenard succeeded in obtaining a new 
and singular compound of oxygen and water to which the term perox- 
ide of hydrogen may be applied. The solution of the peroxide of 
barium, and the subsequent separation of the protoxide is repeated 
a sufficient number of times, in the same portion of dilute muriatic 
acid ; sulphate of silver is then added to separate the muriatic acid, and 
the sulphuric, which then becomes its substitute, is ultimately removed 
by baryta. M. Thenard, in his elaborate essay upon this new com- 
pound, has shown that the process, although in theory sufficiently sim- 
ple, presents many practical difficulties, chiefly arising from the impu 
rities contained in the peroxide of barium. To obtain this substance 
pure, upon which the success of the subsequent operations depends, 
he gives the following directions. Prepare a very pure nitrate of 
baryta, and decompose it by a strong heat in a porcelain vessel, by 
which baryta, containing a portion of silica and alumina, but free from 
manganese, will be obtained ; the latter impurity must always be most 
cautiously avoided, for oxide of manganese possesses the property of 
energetically decomposing the oxygenated water. 
The baryta, broken into small pieces, is then introduced into a luted 
glass tube (the glass should not contain lead) large enough to contain 
about two pounds of it, and being heated to dull redness, a current of 
dry and perfectly pure oxygen gas is passed through it which it rapid- 
ly absorbs ; this operation is to be continued till the oxygen escapes 
from a small tube inserted into the opposite extremity of the larger 
©ne. 
The peroxide thus obtained is pale grey, and frequently some pieces 
are speckled with green, which announces the presence of manganese, 
and which should be rejected : its distinctive character is, that it crum- 
bles when a few drops of water are added to it, without producing 
heat. 
The process then proceeds as follows. Take a certain quantity of 
water (about eight ounces for instance), and add to it a sufficiency of CHLORIDE OF BARIUM. 
pure and fuming muriatic acid to dissolve about 230 grains of baryta : 
put this acid liquor into a glass vessel, which during the operation must 
be surrounded by ice : then take about 185 grains of the peroxide, 
rub it into a tine paste with a little water in an agate mortar, and pul 
it into the acid liquor with a box-wood spatula ; it soon dissolves with- 
out effervescence : to this solution add pure sulphuric acid drop by 
drop, stirring it with a glass rod, till it is in slight excess, which is known 
by the readiness with which the sulphate falls : then dissolve a second 
portion of the deutoxide and precipitate as before, taking care to use 
enough but not too much sulphuric acid. The liquor is now to be fil- 
tered, and the residue washed with a little water, so as to keep up the 
original measure by adding it to the, first portion : a second and third 
washing of the residue with very small quantities of water may be ad- 
visable, and these liquors should be kept apart for the purpose of 
washing the filters in subsequent operations. 
A fresh portion*of the peroxide is then dissolved in the filtrated li- 
quor and decomposed as before, filtering at every two operations and 
washing the filter with the savings of the others. We thus proceed till 
the water is sufficiently oxygenated : when about two pounds of the 
peroxide have been consumed the water will be united to about thirty 
times its volume of oxygen, which is as much as it will retain, unless 
some muriatic acid be added, in which case M. Thenard has made it 
retain 125 volumes. 
When the water is sufficiently oxygenated, it is retained in the ice, 
and supersaturated with the peroxide of barium, which occasions the 
separation of flocculi of silica and alumina, coloured with a little oxide 
of iron and of manganese ; the whole is then filtered as quickly as pos- 
sible, and returned into the vessel surrounded by ice, the baryta is se- 
parated by sulphuric acid, and pure sulphate of silver is added to se- 
parate the muriatic acid, upon which the liquid, before milky, becomes 
suddenly clear. The sulphuric acid is ultimately separated by baryta, 
the liquor filtered and placed in a shallow vessel, under the air-pump 
receiver, containing a basin of sulphuric acid ; the receiver being ex- 
hausted, the water evaporates and is absorbed by the acid, while the 
peroxide of hydrogen being less vaporisable remains ; if it give out 
any oxygen, which sometimes happens from its containing impurities, a 
drop or two of weak sulphuric acid prevents its further evolution. 
The peroxide of hydrogen thus concentrated has the following pro- 
perties : its specific gravity is 1.45; it is colourless anlf inodorous ; it 
blisters the cuticle of the tongue, and has a peculiar metallic taste. It 
does not congeal when exposed to cold, unless diluted. It is rapidly 
decomposed at a heat below 212°, and very slowly at ordinary tempe- 
ratures ; it may be long kept at 32°. It is decomposed by the pile with 
the same phasnomena as water. It is decomposed by all metals except 
iron, tin, antimony, and tellurium : the metals should be finely divided, 
or in powder : silver and oxide of silver decompose it very suddenly 
with the evolution of heat and light : platinum and gold produce the 
same phaenomena; lead and mercury slowly separate the oxygen. 
Orpiment and powdered sulphuret of molybdenum act upon it with 
the same violence as silver; the peroxides of manganese and of lead, 
also, occasion its instant decomposition. 
631. Chloride of Barium may be obtained by heating baryta in chlo- 
rine, in which case oxygen is evolved : or more easily, by dissolving HYPOSULPHITE OF BARYTA. 
carbonate of baryta in diluted muriatic acid. By evaporation, tabular 
crystals are obtained, soluble in 5 parts of water at 60° ; and consist- 
ing, when dry, of 70 barium 36 chlorine = 106. Its taste is pun- 
gent and acrid ; when exposed to heat, the water of crystallization se- 
parates, and the dry chloride enters into fusion. It is insoluble in al- 
cohol. 
632. Chlorate of Baryta is formed in the same way as chlorate of po- 
tassa (546). It crystallizes in quadrangular prisms, soluble in four 
parts of water, at 60®. It consists of 
1 
proportional of baryta = 
= 78 
1 
chloric acid 1 
= 76 
154 
Or of 1 
proportional of barium 
= 70 
6 
oxygen 
= 48 
1 
chlorine 
= 36 
154 
Gay-Lussac procured chloric acid (221) by the action of sulphuric 
acid upon this salt. 
633. Iodide of Barium is easily formed by acting upon baryta by hy- 
driodic acid, and evaporating the solution. It may also be formed by 
heating baryta in hydriodic gas ; water and iodide of barium are the re- 
sults. 
634. Iodate of Baryta is a very difficultly soluble compound ; the hy- 
driodate is crystallizable and very soluble. 
635. Nitrate of Baryta may be produced by dissolving the native 
carbonate in nitric acid, evaporating to dryness, re-dissolving, and crys- 
tallizing; it forms permanent octoedral crystals. Its taste is acrid 
and astringent. It is soluble in 12 parts of cold and 4 of boiling wa- 
ter ; it is decomposed by a bright red heat, furnishing pure baryta. 
It consists of 
78 baryta 
54 nitric acid 
132 
The crystals contain two proportionals of water, or 132 dry nitrate 
+ 18 water. 
If a moderately strong solution of the nitrate of baryta be added to 
nitric acid, a precipitation of nitrate of baryta takes place, in conse- 
quence of the abstraction of water by the acid ; hence in using nitrate 
of baryta as a test of the presence of sulphuric acid in nitric acid, 
(277) the latter should be considerably diluted previous to its applica- 
tion. 
636. Sulphuret of Barium is a brown compound, which acts upon 
water as already described, producing hydrosulphur et of baryta. 
637. Hyposulphite of Baryta.—This salt is thrown down on pouring 
muriate of baryta into a solution, not too dilute, of hyposulphite of 
lime ; it is a white powder soluble without decomposition in muriatic 
acid ; at a low heat it takes fire and (he sulphur burns off. When the SULPHATE OP BARYTA. 
. solutions from which it is precipitated are dilute, it falls, after some 
minutes, in small crystalline grains, followed by a copious separation 
of the salt.—Herschel, Edinburgh Philosophical Journal, i. 20. 
638. Sulphite of Baryta is insoluble in water, and formed by adding 
sulphite of potassa to muriate of baryta. 
639. When sulphurous acid gas is passed into water holding perox- 
ide of manganese in suspension a neutral solution is obtained, composed 
of sulphate and hyposulphate of manganese. These salts are decom- 
posed by excess of baryta, and a soluble hyposulphate of baryta is 
formed, through which carbonic acid is passed, in order to saturate any 
excess of baryta; and the whole being heated to drive off carbonic 
acid which holds a little of the carbonate in solution, the hyposulphate 
of baryta is obtained, and may be purified by crystallization. The so- 
lution of this salt may be decomposed by the careful addition of sul- 
phuric acid, and the hyposulphuric acid is thus obtained in solution. 
This acid is inodorous, sour, and may be concentrated by exposure 
to a vacuum with sulphuric acid : it is decomposed by a heat below 
that of boiling water, sulphurous acid is disengaged, and sulphuric acid 
remains. It perfectly saturates bases, and forms soluble salts with 
baryta, strontia, lime, oxide of lead, and probably with all other bases. 
(,Annales de Chim. et Phys. x. 312 ) The hyposulphate of baryta cry- 
stallizes in quadrangular prisms variously terminated ; 100 parts of 
water at 60° dissolve about 14 parts. It consists of 
1 
proportional of baryta 
. — 78 
1 
hyposulphuric acid 
= 72 
2 
water 9X2 .... 
. = 18 
168 
Or it may be stated as containing in its dry state 
1 baryta 
Hvposulphuric acid \ { sulphuric acid 
1 ( 1 sulphurous acid 
= 78 
= 40 
= 32 
150 
640. Sulphate of Baryta is an abundant natural product; it is insoluble 
and therefore produced whenever sulphuric acid or a soluble sulphate, 
is added to any soluble salt of baryta ; hence the solutions of baryta are 
accurate tests of the presence of sulphuric acid. Sulphate of baryta 
consists of one proportional of sulphuric acid and one of baryta. 
40 sulphuric acid 
78 baryta 
118 
641. Native Sulphate of Baryta, Heavy Spar, or Baroselenite, is prin- 
cipally found in the mines of Westmorland and Cumberland, and in 
Transylvania, Hungary, Saxony, and Hanover. A variety met with in 
Derbyshire, is called cawk. It occurs massive, and crystallized in a 
great variety ot forms. Its primitive figure is a rhomboidal prism, the 
angles of which are 101° 42', and 78° 18'. It is harder than carbo- PHOSPHITE OP BARYTA. 
aate of lime, but not so hard as fluate of lime. Its specific gravity 
is 4.7. 
When native sulphate of baryta is heated it decrepitates and at a high 
temperature fuses into an opaque white enamel : it was employed in 
the manufacture of jasper ware by the late Mr. Wedgwood. When 
formed into a thin cake with paste, and heated to redness, it acquires 
the property of phosphorescence. This was first ascertained by Vin- 
cenzo Cascariolo, of Bologna, whence the term Bologna phosphorus is 
applied to it. (186). The artificial sulphate of baryta is used as a 
pigment, under the name of permanent white. It is very useful for 
marking phials and jars in a laboratory. Sulphate of baryta is sparing- 
ly soluble in sulphuric acid. 
642. As the native sulphate is a common and abundant compound, 
several processes have been contrived for obtaining from it pure bary- 
ta. This may be effected by reducing the crystallized sulphate to a 
fine powder, and heating it red hot for half an hour in a silver crucible 
with three parts of carbonate of potassa : the fused mass is then boiled 
repeatedly in water, till it no longer affords any thing soluble in that 
liquid ; the insoluble residue, consisting chieffy of carbonate of baryta, 
may be digested in dilute nitric acid, by which nitrate of baryta is 
formed, and which will yield the pure earth by exposure to heat as 
above-mentioned. (635). 
Another method consists in exposing to a red heat, in an earthen 
crucible, a mixture of six parts of finely powdered sulphate oft>aryta, 
with one of powdered charcoal, for half an hour. This converts the 
sulphate into sulphuret of baryta, which is to be dissolved in hot water, 
the solution filtered and mixed with solution of carbonate of soda as 
long as it occasions a precipitate, which when washed and dried, is 
carbonate of baryta. Or, by adding muriatic acid to the liquid sulphu- 
ret, sulphur is thrown down and sulphuretted hydrogen evolved, and 
muriate of baryta formed, which may be filtered off, and if required, 
decomposed by carbonate of potassa. Or the sulphuret, as it comes 
out of the crucible, may be thrown into dilute nitric acid, by which 
sulphuretted hydrogen is evolved, and a nitrate of baryta formed, which 
may be separated from the remaining impurities by copious washings 
with hot water. 
643. Phosphuret of Barium is produced by passing phosphorus over 
heated baryta ; there is an intense action and a phosphuret of a metallic 
lustre is obtained, which acts upon water, and affords a solution con- 
taining Hypophosphite of Baryta.—See Chap. IV., Sect. iv. 
644. Hypophosphite of Baryta, like the other hypophosplfites, is 
very soluble and scarcely crystallizable. 
645. Phosphite of Baryta was obtained by Berzelius by adding mu- 
riate of baryta to phosphite of ammonia ; a crust of phosphite of ba- 
ryta was formed in 24 hours, consisting of 
Phosphorous acid 
24.31 
Baryta 
67.24 
Water 
8.45 
Ann. de Own. et Phys., ii. 231. STRONTIUM. 
646. Phosphate of Baryta consists of 
28 
phosphoric acid 
78 
baryta 
106 
It is insoluble in water ; and, therefore, formed by adding a solution 
of phosphoric acid or phosphate of soda to nitrate or muriate of ba- 
ryta. 
Berzelius has described a crystallizable Bi-phosphate of Baryta, 
obtained by digesting the phosphate in phosphoric acid ; and a Sesqui- 
phospliate, obtained by pouring the bi-phosphate into alcohol, which 
occasions a precipitate of a white tasteless powder, composed of 1 pro- 
portional of baryta + 1.5 proportional of acid. 
647. Carbonate of Baryta is found native. Artificially produced, it 
is a white compound insoluble in water, containing 
22 carbonic acid 
78 baryta 
100 
It is poisonous. 
648. Native Carbonate of Baryta was first discovered at Anglesark, 
in Lancashire, by Dr. Withering, and hence acquired the name of With- 
erite. it has also been found in Wales, Cumberland, Durham, West- 
morland, and Shropshire. Its primitive crystal is an obtuse rhomboid : 
sometimes it forms pyramidal six-sided prisms. That found in Lanca- 
shire is in globular masses of a radiated structure. It is useful as a 
source of pure baryta and its salts, and though not soluble in water, is 
poisonous. It dissolves very sparingly in solution of carbonic acid, 
whence the superiority of baryta water to lime water in some cases as 
a test of carbonic acid. The native carbonate of baryta is much more 
difficult of decomposition by heat than the artificial; if mixed with a 
little charcoal powder, and kept for some time in a red heat, carbonic 
oxide escapes, and pure baryta is formed. 
649. Borate of Baryta is an insoluble white powder. 
650. The soluble barytic salts furnish white precipitates of carbonate 
and sulphate of baryta, upon the addition of carbonate or sulphate of 
soda. They give a yellow tinge to the flame of spirit of wine. The 
sulphate is insoluble in nitric acid and in the alcalis, and very sparing- 
ly soluble in sulphuric acid. 
Nearly all the barytic compounds are poisonous ; the safest antidote 
is solution of sulphate of soda, or dilute sulphuric acid. (Orfila, 
Traits des Poisons, Tom. i. 2me. p. 167.) The muriate of baryta 
has been employed in medicine, but the principal use of baryta is in 
the chemical laboratory. It is possible that pure baryta might be eco- 
nomically used for the decomposition of sulphate of soda, to obtain the 
pure alcali. 
Section VI. Strontium. 
651. This metal is procured from the earth strontia by the same 
process as barium-, which metal it resembles in appearance. 652. Oxide of Strontium, or the earth Strontia, is procured by the ig- 
nitibn of the pure nitrate ; it is of a grey colour and very difficult of 
fusion when free from water ; it forms a pulverulent, and a crystallized 
hydrate. Strontia consists of 
NITRATE OF STRONTIA. 
44 
8 
strontium 
oxygen 
52 
These proportions are theoretically deduced from the sulphate, for 
52 parts of strontia combine with 40 parts of sulphuric acid, containing 
16 sulphur and 24 oxygen ; hence 8, or one third of the oxygen exist- 
ing in the acid, must be contained in the base (527), and 52 — 8 — . 
44, the proportion of metal in the protoxide, and the representative 
number of strontium. 
The pulverulent hydrate contains 
52 
strontia 
9 
water 
61 
At the temperature of 60°, 2 parts of water dissolve 3 of the crys- 
tallized hydrate. 
1 part of strontia requires about 160 of water at 60° for its solution. 
Strontia water is transparent and colourless ; it greens vegetable blues, 
and its taste is styptic and acrid. 
653. Chlorine and Strontium.—This compound which has also been 
called Muriate of Strontia, is commonly procured by dissolving carbo- 
nate of strontia in muriatic acid. It crystallizes in slender six-sided 
prisms, soluble in twice their weight of water, at 60°. When chlorine 
is made to act upon strontia, it is absorbed, and oxygen evolved : the 
resulting compound contains 
44 
36 
strontium 
chlorine 
80 
It is of a grey colour. It dissolves in alcohol, and the solution burns 
with a purple-coloured flame. 
654. Chlorate of Strontia is a very soluble and deliquescent salt, dif- 
ficultly crystallizable, and detonates when thrown upon red-hot coals 
with a beautiful purple light. 
655. Iodide of Strontium may be formed as iodide of barium. Dis 
solved in water, and carefully evaporated, it furnishes delicate pris 
matic crystals of Hydriodate of Strontia, which, heated in close vessels 
fuses and becomes iodide of strontium by loss of water. 
656. Iodate of Strontia is a very difficultly soluble compound ; it is 
resolved at a red heat into oxygen, iodine, and strontia. 
657. Nitrate of Strontia crystallizes in octoedra and dodecaedra ; it 
is soluble in its weight of water at 60°. It consists of 
52 
strontia 
54 
nitric acid 
106 208 
Its taste is pungent and cooling. At a red heat the acid is evolved 
and partly decomposed, and strontia remains. 
This salt is used in the red fire employed at the theatres, which 
consists of 40 parts of dry nitrate of strontia, 13 of powdered sulphur, 
5 of chlorate of potassa, and 4 of sulphuret of antimony. The chlorate 
and sulphuret should be separately powdered, and mixed together ori 
paper with the other ingredients ; a very small quantity of powdered 
charcoal may also be added. 
658. Sulphuret of Strontium may be formed by fusing strontia and 
sulphur in a green glass tube ; or by exposing the powdered sulphate 
to a red heat with charcoal. It dissolves in water with the same phe- 
nomena as sulphuret of potassa, and its solution furnishes, by cautious 
evaporation, crystals of hydrosulphuret of strontia. 
659. Hyposulphite of Strontia is formed by passing sulphurous acid 
into the liquid sulphuret : it crystallizes in rhomboids permanent at 
common temperatures and soluble in about 5 parts of water at 60°. 
(Gay-Lussac, Annales de Chimie, lxxxv.) According to Mr. Herschel, 
this salt is doubly refractive. Its taste is bitter, and it is insoluble in 
alcohol. 
660. Sulphite of Strontia has not been examined. 
661. Sulphate of Strontia occurs native. It is nearly insoluble, 1 
part requiring 4000 of water for its solution. When heated with char- 
coal, its acid is decomposed, and sulphuret of strontia is formed, which 
affords nitrate by the action of nitric acid. This process, equally prac- 
ticable upon sulphate of baryta (642), is sometimes adopted to obtain 
the earth. Sulphate of strontia dissolves in hot sulphuric acid, but is 
thrown down upon adding water. It consists of 
PHOSPHATE OF STRONTIA. 
52 
strontia 
40 
acid 
92 
662. The Native Sulphate of Strontia is sometimes of a blue tint, and 
has hence been called celestine. Sometimes it is colourless and trans- 
parent. Its primitive form is a prism of 104° 48' and 75° 42' with a 
rhomboidal basis. It has been found at Strontian in Argyleshire ; in 
the vicinity of Bristol; and at Montmartre near Paris. The finest 
crystallized specimens are accompanied with native sulphur, from Sici- 
ly. Its specific gravity is 3.2. 
663. Hypophosphite of Strontia has been examined by Dulong: it is 
a very soluble and difficultly crystallizable salt. 
664. Phosphite of Strontia has not been examined. 
665. Phosphate of Strontia is an insoluble white salt, containing 
52 
28 
strontia 
acid 
80 
It is soluble in excess of phosphoric acid, which is not the case with 
phosphate of baryta. It is entirely decomposed by sulphuric acid. 
By igniting it with charcoal, phosphuret of strontium js obtained. MAGNESIA. 
666. Carbonate of Strontia exists native. Artificially formed, it is q 
white insoluble body, containing 
52 
22 
strontia 
carbonic acid 
74 
When strongly heated with a littje bharcoal powder, it is decompos- 
ed, carbonic oxide is given off, and pure strontia remains. 
667. Native Carbonate of Strontia or Strontianite is a rare mineral. It 
has a greenish tint, and occurs in radiated masses, and sometimes in 
acicular and hexaedral crystals. It was first discovered in 1787 at 
Strontian in Argyleslfire, whence the name of this earth ; it has also 
been found in Saxony and in Peru. Its specific gravity is 3.6. 
This substance was first examined, and the peculiarities of strontia 
pointed out, by Professor Hope of Edinburgh, in 1791. His experi- 
ments are detailed in the Philosophical Transactions of the Royal Society 
of Fnlinburgh, Vol. iv. p. 44. 
668. Borate of Strontia was formed by Dr. Hope. It is a white pow- 
der soluble in 130 parts of water. 
669. There is in many respects a resemblance betiveen strontia and 
baryta which has led to confusion in analysis. 
The following are some of the most striking points of resemblance. 
They are both found native in the states of sulphate and carbonate only ; 
both sulphates are soluble in excess of sulphuric acid, and nearly insO ’ 
luble in water ; they are decomposable by similar means, as well as 
the native carbonates: they are both crystal livable from their hot 
aqueous solutions, and both attract carbonic acid. The carbonates are 
each soluble with effervescence in most of the acids ; but the native 
carbonates are not so easily acted on as the artificial. Pure ammonia 
precipitates neither one nor the other. 
The following are essential distinctions. Baryta and all its salts, ex- 
cept the sulphate, are poisonous. The corresponding strontitic salts 
are innocent. Baryta tinges flame yellow ; strontia, red. Strontia lias 
less attraction for acids than baryta ; hence the strontitic salts are de- 
composed by baryta. The greater number of the barytic salts are less 
soluble than those of strontia, and they differ in their respective forms 
and solubilities. Pure baryta is ten times more soluble ip water than 
pure strontia. 
Section VII. Magnesium, 
670. The metallic base of magnesia ha? not hitherto been obtained 
but, when that earth is negatively electrized with mercury, the resulting 
compound decomposes water, and gives rise to the formation of mag- 
nesia. From the properties of the amalgam it appears that it is a white 
solid metal heavier than water, and highly attractive of oxygen. 
671. Magnesia or Oxide of Magnesium is from indirect 
experiments, to consist of 12 metal + 8 oxygen; its representative NITRATE OF MAGNESIA. 
number, therefore, is 20. It may be procured by exposing the car 
bonate of magnesia to a red heat. Magnesia is a white insipid sub- 
stance, which slightly greens the blue of violets. Its specific gravity 
is 2.3 ; it is almost infusible and insoluble in water. I once succeeded 
in agglutinating a small portion of this earth in the voltaic flame, and 
whilst exposed to this high temperature, it was perfectly fused by di- 
recting upon it the flame of oxygen and hydrogen. A mixture of 
magnesia and lime is scarcely more fusible than the pure earth. It 
does not absorb carbonic acid or moisture, as is the case with the other 
alcaline earths. 
672. Native Magnesia is a very rare mineral, and has hitherto beer- 
found only at Hoboken, in New-Jersey. Its colour is greenish white ; 
its texture lamellar and soft. According to the analysis of Dr. Bruce, 
it consists of 
70 
30 
magnesia 
water 
100 
673. Chloride of Magnesium may be obtained by passing chlorine 
over red-hot magnesia ; oxygen is expelled, and a substance obtained 
which moisture converts into muriate of magnesia. 
674. Muriate of Magnesia is very deliquescent, and difficultly crys- 
tallized. Its solution has a bitter saline taste. Exposed to heat and 
air, muriatic acid flies off, and the magnesia remains pure. It consists 
of 
Magnesia . . . 
20 
Muriatic acid 
37 
57 
675. Muriate of Magnesia is found in a few saline springs, and also 
in the water of the ocean. By evaporating a pint of sea-water wc 
obtain 
Common Salt . 
Muriate of Magnesia . . . . 
... 23 
Sulphate of Magnesia . . . 
. . . 15.5 
Sulphate of Lime 
... 7.1 
226.1 
Murray Is Analysis of Sea-lVater, Edinburgh Phil. Trane., Vol. viii 
p. 205. 
The average specific gravity of sea-water is 1.026 or 1.028. It 
freezes at about 28.5°, and does not appear materially to differ in com- 
position in different latitudes, provided it be taken from a sufficient 
depth. Near the mouths of rivers, and in the vicinities of melting ice 
or snow, its composition will of course vary. 
676. Chlorate of Magnesia is a bitter deliquescent salt. 
677. Hydriodate of Magnesia is deliquescent, and loses hydriodic 
acid by exposure to heat. 
Iodide of Magnesium has not'been examined. 
678. Nitrate of Magnesia crystallizes in rhomboidal prisms, deli- SULPHATE OF MAGNESIA. 
quescent, and soluble in its weight of water. Its taste is cooling and 
bitter, and it is decomposed at a red heat. It contains 
Magnesia 20 
Nitric acid 54 
74 
079. JImmonio-Nitrate of Magnesia may be obtained by evaporating" 
a mixed solution of nitrate of ammonia and nitrate of magnesia ; it 
forms prismatic crystals of a bitter acrid taste, soluble in about II 
parts of water at 60°, and less deliquescent than their component salts 
separately.—Fourckoy, Annalcs de Chimic, iv. 215. 
680. Sulphuret of Magnesia.—Sulphur and magnesia do not appear 
to form a complete sulphuret, for when melted together the compound 
does not dissolve in water ; and when heated the sulphur burns off. 
681. Hyposulphite of Magnesia may be formed by boiling flowers of 
sulphur in solution of sulphite of magnesia ; it is bitter very soluble 
but not deliquescent. Being more soluble in hot than cold water, it 
readily crystallizes as its solution cools ; heated, the sulphur escapes, 
but it is not very combustible. 
682. Sulphite of Magnesia is prepared by passing sulphurous acid 
through water containing diffused magnesia. It forms tetraedral crys- 
tals soluble in 20 parts of water at 60°. 
683. Sulphate of Magnesia is a commonly occurring compound of 
this earth, much used in medicine as an aperient. It is largely con- 
sumed in the preparation of carbonate of magnesia. It crystallizes in 
four-sided prisms with reversed dihedral summits ; or four-sided pyra- 
mids. Its taste is bitter. It is soluble in its own weight of water at 
60°. When exposed to a red heat, it loses its water of crystallization, 
amounting to about 50 per cent., but is not decomposed. It consists of 
Magnesia . . . . 
20 
Sulphuric aciil 
40 
60 
In its crystallized state, it may be considered as composed of 1 pro- 
portional of dry sulphate + 7 proportionals of water, or 60 sulphate 
63 water 
123 
684. This salt is usually obtained from sea-water, the residue of 
which, after the separation of common salt, i,s known by the name of 
bittern, and contains sulphate and muriate of magnesia ; the latter is 
decomposed by sulphuric acid : a portion of muriate of magnesia often 
remains in the sulphate and renders it deliquescent: it is also occasion- 
ally obtained from saline springs ; and sometimes by the action of sul- 
phuric acid on magnesian limestone. It was once procured from the 
springs of Epsom in Surrey, and hence called Epsom salt. It has befin 
found native, constituting the bitter salt and hair salt of mineralogists : 
it not unfrequently occurs as a fine capillary incrustation upon the 
damp walls of cellars and new buildings. 
685. The sulphate of magnesia of commerce is occasionally adul- terated with small crystals of sulphate of soda; the fraud is detected 
by the inferior weight of the precipitate, occasioned by adding carbo- 
nate of potassa ; 100 parts of pure crystallized sulphate of magnesia fur- 
nishing a precipitate of about 40 parts of dry carbonate. 
686. Ammonio-Sulphate of Magnesia may be obtained by mixing 
solution of sulphate of ammonia with solution of sulphate of magne- 
sia ; or by pouring ammonia into a solution of the sulphate of magne- 
sia, in which case, part only of the magnesia is thrown down, the re- 
mainder forming with the sulphate of ammonia this triple salt. It crys- 
tallizes in octoedry and consists of 
CARBONATE OF MAGNESIA. 
68 sulphate of magnesia 
82 sulphate of ammonia 
100 
Fourcroy, Annalcs de Chimic, vi. 
687. Sulphate of Potassa and Magnesia forms rhomboidal crystals* 
scarcely more soluble than sulphate of potassa, and of a bitter taste. 
688. Phosphuret of Magnesia, not examined. 
689. Hypophospliite of Magnesia, not examined. 
690. Phosphite of Magnesia, not examined. 
691. Phosphate of Magnesia is formed by adding the carbonate of 
magnesia to phosphoric acid. It is insoluble. According to Fourcroy, 
crystals of phosphate of magnesia may be obtained by mixing the 
aqueous solutions of phosphate of soda and sulphate of magnesia. 
The bi-phosphate crystallizes in irregular six-sided prisms, soluble m 
14 parts of water at 60°, and efflorescent* 
692. Ammonio-Phosphate of Magnesia is formed by mixing the solu- 
tions of phosphate of ammonia, and phosphate of magnesia ; it preci- 
pitates in the form of a white crystalline powder, or in small four-sided 
prisms, tasteless, and scarcely soluble in water, but readily soluble in 
dilute muriatic acid. Exposed to a high temperature it falls into pow- 
der, evolves ammonia, and fuses with difficulty. According to Four- 
croy, it contains equal weights of phosphate of ainmmonia, phosphate 
of magnesia, and Water. 
To separate magnesia from other earths, Dr. Wollaston availed him- 
self of the formation of this triple phosphate. A mixture, for instance, 
of lime and magnesia may be dissolved in muriatic acid ; and, upon the 
addition of bi-carbonate of ammonia, the lime is thrown down in the 
state of carbonate, but the magnesia is retained by the excess of car- 
bonic acid* Filter and add a saturated solution of phosphate of soda, 
and in a short time the ammonio-magndsian phosphate falls down, 100 
grains of which are equivalent to about 20 of magnesia. In occasion- 
ally employing this process, however, I have never been able to throw 
down the whole of the magnesia, a portion being under all circumstan- 
ces retained in solution. 
693. Carbonate of Magnesia is generally procured by adding carbo- 
hated alcalis to a solution of sulphate of magnesia. It is a white, insi- 
pid, and insoluble powder, which loses its acid at a red heat, and thus 
affords pure (calcined) magnesia. It contains 
20 
magnesia 
22 
carbonic acid BbRAtE OP MAGNESIA. 
694. Carbonate of magnesia was first used in medicine early in the 
last century. It is often obtained from sea-water, after the separation of 
its common salt. It has been found native in Piedmont and Moravia, 
constituting the mineral called magnesite. It has also been found at 
Hoboken in veins in a serpentine rock, accompanying the native hy- 
drate (672). It is generally white and friable, and in some places in 
fine acicular crystals. 
695. Bi-carbonate of Magnesia.—Carbonate of magnfesia is soluble in 
excess of carbonic acid, and this solution afl’ords efflorescent crystals of 
bi-carbonate containing 
20 
magnesia 
44 
carbonic acid 
64 
This solution of magnesia, in excess of carbohic acid, is very useful 
in some calculous complaints. 
696. Borate of Magnesia may be formed artificially. It occurs na- 
tive in a mineral called boracite, hitherto only found in the duchy ot 
Luneburgh. Its primitive form is the cube, but the edges and angles 
are generally replaced by secondary planes, and four of the angles are 
always observed to present a greater number of facets than the other 
four : these crystals become electric by heat; the most complex angles 
being rendered positive, and the simplest negative. It sometimes con- 
tains lime. 
697. The salts of magnesia are for the greater part soluble in water, 
and afford precipitates of magnesia, and of carbonate of magnesia, upon 
the addition of pure soda, and of carbonate of soda. Phosphate of soda 
occasions no immediate precipitate when added to a magnesian salt, but 
the addition of ammonia causes a white precipitate of the tripple am- 
monio-magnesian phosphate. 
698. The fossils which contain magnesia are generally soft and appa- 
rently unctuous to the touch; they have seldom either lustre or 
transparency, and are generally more or less of a green colour. Stea- 
tite or soapstone, talc, and asbestos may be taken as instances. The 
chrysolite also contains more than half its weight of magnesia. The 
mineral called bitter spar, of which the finest specimens come from 
the Tyrol, contains 45 per cent, carbonate of magnesia, 52 carbonate of 
lime, and a little iron and manganese. Its primitive crystal is a rhom- 
boid nearly allied to that of carbonate of lime ; its angles being 106a 
20', and 73° 80'. It is of a yellowish colour, and a pearly lustre ; 
semi-transparent and brittle. A variety found at Miemo in Tuscany, 
has been called Miemite. The species of marble, termed Dolomite, 
found in the Alps, and in Icolmkill in Scotland, contains also a large 
quantity, generally 40 per cent, of carbonate of magnesia. The same 
may be said of the magnesian limestone of Derby and Nottingham : it is 
generally of a yellowish colour, and less rapidly soluble in dilute mu- 
riatic acid, than the purer limestones, whence the French have term- 
ed it chaux carbonatee lente. The lime which it affords is much esteem- 
ed for cements, but for agricultural purposes it is often mischievous, in 
consequence of its remaining caustic for a very long time, and thus in- 
juring the young plant. 
699. The separation of magnesia and lime is a problem of some im- 
portance in analytical chemistry, as they often exist together in the 
same mineral, more especially in the varieties of magnesian limestone. manganese and oxygen. 
When solution of carbonate of ammonia is added to the mixed solution of 
lime and magnesia in nitric or muriatic acids, carbonate of lime falls, 
and the magnesia is retained in solution and may be separated by boil- 
ing: this method, however simple, is not susceptible of great accura- 
cy, for a portion of carbonate of lime will always be retained along 
with the magnesia in solution, and a triple ammoniaco-magnesian salt 
is also formed. Mr. R. Phillips (Quarterly Journal, vi. 317) proposes 
the following process : “ To the muriatic or nitric solution of lime and 
magnesia, add sulphate of ammonia in sufficient quantity; evaporate 
the mixture gradually to dryness, and then heat it to redness till it 
ceases to lose weight by the volatilization of the muriate or nitrate of 
ammonia formed : note the weight of the mixed salt, reduce it to pow- 
der and wash it with a saturated solution of sulphate of lime till all the 
sulphate of magnesia appears to be dissolved ; dry the sulphate of lime 
left, and by deducting its weight from that of the mixed sulphates the 
quantity of sulphate of magnesia dissolved will appear,” After repeat- 
ed trials of the various modes of separating lime and magnesia, I am 
induced to consider the following as least defective. To the mixed so- 
lution of lime and magnesia add oxalate of ammonia slightly acid, col- 
lect the precipitate, wash and dry it. 65 parts indicate 28 of lime. 
If nitric or muriatic acid were used for solution, the magnesia may af- 
terwards be obtained by evaporation and heating the residue to redness 
in a platinum crucible till it ceases to lose weight. If sulphuric acid 
were the solvent, the same operation affords dry sulphate of magnesitt 
«f w hich 60 parts are equivalent to 20 magnesia. 
Section VIII. Manganese. 
700. The common ore of manganese is the black or peroxide, which 
is found native in great abundance. 
The metal may be procured by exposing the protoxide mixed with 
charcoal, to an intense heat. It is of a bluish white colour, very brit- 
tle, and difficult of fusion. When exposed to air, it becomes an oxide. 
Its specific gravity is 8. 
701. Manganese and Oxygen.—There are three definite oxides of 
manganese. The protoxide may be obtained by digesting the native . 
black oxide in muriatic acid. Chlorine is abundantly evolved, and the 
hydrogen of the muriatic acid unites with part of the oxygen of 
the oxide to produce water. The metal thus partly deoxidized, 
is dissolved by the remaining muriatic acid, forming a muriate of 
manganese. Iron is almost always present, which, as Mr. Hatchett 
has shown, may be easily separated by neutralizing the muriatic solu- 
tion with ammonia. The oxide of iron is directly precipitated, but ox- 
ide of manganese remains in solution and may be separated by excess of 
ammonia*. The solutions of protoxide of manganese furnish a white 
* On the separation ofiron from manganese, see Quarterly Journal of Science and the Arts! 
Vek vi. p. 153. PEROXIDE OF MANGANESE. 
precipitate with the alcalis, which is a hydrated oxide of manganese, and 
which, when dried in close vessels, acquires an olive colour, and is the 
protoxide. Exposed to moist air, it passes into the state of deutoxide 
and peroxide. 
702. When peroxide of manganese is heated red-hot till it ceases 
to give out gas, a dark reddish-brown deutoxide of manganese remains, 
which, when acted upon by sulphuric acid, is, according to Gay-Lus- 
sac, resolved into protoxide and peroxide. Exposed to moist air it 
absorbs oxygen, and is partly re-converted into peroxide. The deu- 
toxide is most easily obtained pure, by triturating peroxide of manga- 
nese in fine powder with superoxalate of potassa and water: a pink 
solution is obtained, from which ammonia throws down the deutoxide. 
703. The Peroxide of Manganese is black ; it is not soluble in 
acids ; and abounds as a natural product. 
Native Peroxide of Manganese is found in Devonshire, Somerset- 
shire, and Aberdeenshire, and occurs compact, and crystallized. The 
crystallized varieties have a grey metallic lustre, and are found acicu- 
larly radiated, and in rhomboidal prisms. It is generally blended with 
sulphate of baryta. 
704. It appears probable that these are the only definite oxides of 
manganese. Their composition is variously stated by various che- 
mists ; according to the analysis of Berzelius (Annales de Chimie, 
Ixxxvii.) they arG composed as follows : 
Protoxide. 
Deutoxiue. 
Peroxide. 
Manganese 
100. 
100. 
100. 
Oxygen 
28.1 
42.16 
56.2 
From which it appears that the proportions of oxygen to each other, 
are as 1., 1.5, and 2 ; and 28.1 : 100 : : 8 : 28.4, as the representa- 
tive number of manganese. Dr. Davy’s analysis of the chloride of 
manganese (707) which was made in an unexceptionable way, gives 
the number 28.6. As further experimental evidence is wanting, we 
shall not be far from the truth in assuming *28.0 as the equivalent of 
•manganese, and the three oxides will then consist of 
Protoxide. 
Deutoxids. 
Peroxide. 
Manganese, 1 proporl. 28.0 
28.0 
28.0 
Oxygen ... 1 8 1.5 propl. 
12. 
2 propl, 16. 
36 
40 
44 
705. When equal parts of black oxide of manganese and nitre are 
ignited, a compound results which has been called cameleon mineral, in 
consequence of the changes of colour which its aqueous solution ex- 
hibits. M. M. Chevillot and Edwards have ascertained, that in tills 
compound the black oxide of manganese has absorbed an additional 
proportion of oxygen and acquired the property of forming a neutral 
manganesate of potassa, which exists in the red cameleon, and may be 
obtained in crystals. When there is excess of alcali, the cameleon is 
green.—Annales de Chimie et Physique, Tom. iv. 
* Thomson in his late paper (Ann. Phil. vol. 17, for April 1821), finds by experiment the 
composition of sulphate of manganese 
deducting 1 atom oxygen=8, leaves 28 for manganese, which will be adopted he:*, 
Sulphuric acid .... 
40 
Protox. mang1 
36; new HYPOSULPHITE oe manganese. 
700. Manganese and Chlorine.—By burning the metal in chlorine* 
or by exposing muriate of manganese to a strong heat, a pink semi- 
transparent flaky substance is obtained, which, when dissolved in wa 
ter, produces a muriate of manganese. 
707. Muriate of Manganese may also easily be formed by heating 
excess of the black oxide with muriate of ammonia in a crucible, dis- 
solving the mass in water and filtering. If this solution be evaporated 
to dryness and fused out of the contact of air, the crystallized chloride 
is obtained. Heated in contact of air, it is decomposed, and oxide of 
manganese remains. In this decomposition it is a question whether the 
chlorine is expelled by the superior attraction of the oxygen for man- 
ganese ; or whether the moisture in the air, or in the compound itself 
is concerned in the change. This chloride consists, according to Dr. 
Davy (Phil. Trans. 1812, p. 184) of 
54 chlorine 
46 manganese 
100* 
Sp that it may be regarded as a compound of 
1 proportional manganese 
28 
l chlorine 
36 
64 
708. Chlorate of Manganese has not been examined, nor has the ac~ 
tion of iodine or of its acids upon this metal been investigated. 
709. Nitrate of Manganese.—Dilute nitric acid readily dissolves pro-r 
toxide of manganese, and forms a very soluble and difficultly crystalli- 
zable proto-nitrate. The same salt may. be obtained by digesting pe- 
roxide of manganese in nitric acid with a portion of gum or sugar, which 
abstracts oxygen, carbonic acid is evolved, and the protoxide dissolved 
by the acid. Exposed to light, the solution of the protonitrate lets fall 
a portion of peroxide of manganese. 
When dilute nitric acid is poured upon the deutoxide of manganese,., 
a protonitrate and peroxide are formed. 
The composition (theoretical) of nitrate of manganese j% 
36 protoxide 
J54 acid 
90 
710. Manganese and Sulphur appear unsusceptible of combination; 
but a compound of oxide of manganese and sulphur is found in Transyl 
vania and Cornwall. It is of a blackish grey colour and metallic lustre. 
The black oxide of manganese heated with sulphur forms a greenish 
compound, and abundance of sulphurous acid is evolved : is this a sul- 
phuret, or a sulphuretted oxide ofmanganese ? 
711. Hyposulphite of Manganese remains in solution when sulphate 
of manganese is decomposed by hyposulphate of lime. 
* This analysis of Dr. John Davy, differs from ail the compositions of manganese, and 
may be considered as incorrect. Thomson, by the experiment last alluded to, has proved its 
composition to be 
Chlorine 
Manganese 217 
712. Sulphate of Manganese is formed by dissolving the protoxide or 
protocarbonate in the acid, and evaporating to dryness : a white proto sul- 
phate is formed, which crystallizes in rhomboidal prisms, and consists of 
IRON. 
36 
protoxide 
40 
sulphuric acid 
76 
It is very soluble in water, and has a bitter styptic taste : at a bright 
red heat it gives out oxygen, and sulphurous acid and deutoxide of man- 
ganese remain. It may also be obtained by mixing peroxide of manga- 
nese into a paste with sulphuric acid, and heating it in a basin nearly to 
redness : oxygen is evolved, and the dry mass washed with water affords 
the sulphate. 
713. Deutosulphate of Manganese is formed by digesting the deutoxide 
in sulphuric acid diluted with its bulk of water ; a red solution is form- 
ed, but the salt cannot be obtained in a neutral or separate state, for 
the application of heat evolves oxygtm, and forms protosulphate. It is, 
probably, to a little deutosulphate that the occasional red tinge of the 
protosulphate is to be attributed. 
714. Phosphuret of Manganese is of a blue white metallic lustre, and 
considerably inflammable. 
715. Phosphite and Hypophosphite of Manganese have not been ex- 
amined. 
718. Phosphate of Manganese is precipitated in the form of a white 
insoluble powder, by adding phosphate of soda to muriate of manganese. 
717. Carbonate of Manganese is white, insipid, and insoluble in wa- 
ter. It is precipitated by alcaline carbonates from the protomuriate or 
protosulphate, and consists of 
36 
protoxide 
22 
carbonic acid 
58 
718. The salts of manganese containing the protoxide are mostly so- 
luble in water, and the solution becomes turbid and brown by exposure 
to air. They are not precipitated by hydriodic acid ; they furnish 
white precipitates with the alcalis, which soon become discoloured by 
exposure to air ; they are precipitated white by ferro-prussiate of po- 
tasga, and yellow by hydrosulphuret of ammonia. 
719. The native peroxide of manganese is used in the laboratory as 
a source of oxygen, and is largely employed in the preparation of chlo- 
rine, especially by the bleachers. It is used in glass-making, and, when 
added in excess, gives it a red or violet colour. It is also employed 
in porcelain painting ; and it gives common earthen-ware a black colour, 
by being mixed with the materials before they are formed into vessels. 
Section IX. Jr on. 
720. The most important native combinations of iron, whence the 
immense supplies for the arts of life are drawn, are the oxides. Iron 
is also found combined with sulphur, and with several acids ; it is so 
abundant that there are few fossils free from it. It is also found in 
some animal and vegetable bodies ; and in several mineral waters. PROTOXIDE Ot' IRON 
Iron is a metal of a blue white colour, fusible at a white heat. Its 
specific gravity is 7.77. It has not been so long known as many of the 
other metals-; it was, however, employed in the time of Moses for cut- 
ting instruments. It is extremely ductile, but cannot be hammered out 
into very thin leaves. 
721. Iron is sometimes found native, and is usually regarded as of 
meteoric origin, for it is invariably alloyed by a portion of the metal 
nickel, and a similar alloy is found in meteoric stones. Native Iron is 
tlexible, cellular, and often contains a green substance of a vitreous ap- 
pearance. It has been found in Africa, in America, and in Siberia, 
where a mass of it weighing 1GOO lbs. was discovered by Professor 
Pallas. The mass found in Peru, described by Don Rubin de Celis, 
weighed 15 tons. In the year 1751, a mass of the same substance 
was seen to fall from the atmosphere in Croatia. It appeared as a 
large globe of fire, and is preserved in the imperial museum of Vienna. 
722. Iron and Oxygen.—Exposed to heat and air, iron quickly ox- 
idizes. It unites with oxygen in at least two proportions. The pro- 
toxide may be procured by precipitating a solution of sulphate of iron 
by potassa, washing the precipitate out of the contact of air, and dry- 
ing it at a red heat. It is black, and consists of 28 iron -f- 8 oxygen = 
3G. It is supposed by M. Gay-Lussac, that in drying, an additional 
proportion of oxygen is always absorbed, and that the black oxide is a 
deutoxide composed of 100 metal + 37.8 oxygen ; (Ann. de Chim. et 
Phys., Tom. i.) but there is some reason to doubt the accuracy of this 
conclusion. 
The recently precipitated protoxide of iron is sparingly soluble in 
ammonia, and in carbonated alcalis. 
Black protoxide of iron may also be obtained by burning iron in oxy- 
gen gas : this very beautiful experiment was devised by Dr. Ingenhous* 
and is best performed by attaching a straight piece of watch spring, 
wound round with harpsichord wire, to the stopper of an air-jar of oxy- 
gen gas : the end of a brimstone match may be attached to the wire, 
and inflamed at the time of plunging it into the gas ; it heats the wire 
red hot, which then burns and drops in black globules of oxide into the 
water beneath. 
This oxide of iron used to be prepared for pharmaceutical use, by 
moistening iron filings with a small quantity of water, and exposing them 
to the air for a day or two ; a quantity of black oxide thus forms, which 
is separated by washing, and the process repeated till the whole of the 
metal is thus oxidized. It was called martial ethiops. It is black, 
tasteless, and insoluble in .water. 
723. When protoxide of iron is boiled in nitric acid, and precipitated 
by ammonia, washed, and dried at a low red heat, it increases in weight 
and acquires a brown colour. This is the peroxide, composed of 28 iron 
12 oxygen = 40. It has sometimes been called Saffron of .Mars. 
724. The number 2G, as the equivalent of iron is founded on the 
presumption that it exists as a protoxide in the sulphate : now 100 
grains ot pure iron, during solution in sulphuric acid, evolve 170 cubic 
inches of hydrogen at mean temperature and pressure, and consequent- 
ly 85 cubic inches of oxygen = 28.G8 grs. have been transferred to 
the iron : and 28.G8 : 100 : : 8 : 27.9. The quantity of oxygen in the 
peroxide ot iron is shown to be to that in the protoxide as 3 to 2 by the 
following experiment. 100 grains of iron were dissolved in nitric acid 
and the solution evaporated to dryness, and the residue sufficiently OXIDE OF IRON. 
219 
heated to drive off the whole of the acid : 143 grains of peroxide re*- 
mained. So that the composition of these oxides stands thus : 
Protoxide. 
Peroxide. 
Iron. . 100 
..... 100 
Oxygen 28.68 ...... 
43 
128.68 
143 
And 28.68 . 43 : : 8 : 12 = \ proportional of oxygen. 
M. Gav-lussac (Ann. de Chiin. et Phys. i., and Ann. de Chirn. lxxx.) 
has detailed some experiments, which he considers as demonstrating 
the existence of a third delinite oxide of iron, intermediate between 
the above oxides, and composed of iron 100 + oxygen 37.8. Such a 
compound he thinks is obtained by passing steam for a length of time 
over red-hot iron : it seems, however, very questionable whether this 
be a delinite compound : it is rejected by Berzelius, who only admits 
the oxides above described. 
M. Thenard, in describing the oxides of iron, (Trait6 ii. 75. Edit. 2.) 
considers the octoedral and magnetic iron ores as composed of this deu- 
t.oxide, and does notallow of the existence of native protoxide of iron. 
In the present state of the question, however, I should feel rather in- 
dined to view this deutoxide as a mixture of the protoxide and perox- 
ide, than as any definite compound, more especially as the analyses of 
the native magnetic oxides give variable proportions of oxygen. 
In order that the representative number of iron may also be its equi- 
valent number, it is represented by 28. But the peroxide, instead of 
consisting of 1 proportional metal + 2 oxygen, consists of 1 propor- 
tional metal + 1.5 oxygen ; and the chloride and perchloride bear the 
same relation to each other. The case however is different with the 
sulphurets ; for the sulphuret consists of 1 proportional iron + 1 
sulphur : andthe bi-sulphuret of 1 iron + 2 sulphur. 
M. Gay-Lussac has shown the curious fact, that although red-hot 
iron decomposes water, hydrogen is capable of decomposing all the ox- 
ides of iron at a red heat.—Ann, de Chim. et Phys., i. 37. 
725. The Native Oxides of Iron constitute a very extensive and im- 
portant class of metallic ores. They vary in colour, depending upon 
mere texture in some cases ; in others, upon the degree of oxydize- 
ment. Some varieties are magnetic, and those which contain least oxy- 
gen are attracted by the magnet. 
Magnetic Iron Ore is generally black, with a slight metallic lustre. 
It occurs massive and octoedral. It is often sufficiently magnetic to 
take up a needle. Its specific gravity is 4.5. It occurs chiefly in pri- 
mitive countries, and is very abundant at Roslagen in Sweden, where it 
is manufactured into a bar-iron particularly esteemed for making steel. 
Another variety of oxide of iron is called iron glance, and micaceous 
iron ore. It is found crystallized of singular beauty, in the isle of El- 
ba ; and occasionally among the volcanic products of Vesuvius and the 
Lipari Islands. 
A third variety is Haematite, or red iron-stone ; it occurs in globular 
and stalactitic masses, having a fibrous and diverging structure. In 
this country it abounds near Ulverstone in Lancashire ; and most of 
our iron-plate, and wire, is made from it. Sometimes it is of a brown, 
black, or ochraceous colour. 
A fourth variety of oxide of iron, is known under the term of clay- 
irm-stoneon account of the quantity of argillaceous mirth with which 220 
PROTOMURIATE OF IRON. 
it is contaminated. It is found in masses of different shapes and sizes, 
and sometimes in small rounded nodules like peas. Some of the glob- 
ular masses are called ostites. It is abundant in the coal formations of 
Shropshire, South Wales, Staffordshire and Scotland. 
Though this is far from the purest iron ore found in this country, it 
is the chief source of the cast and bar iron, in ordinary use. Its em- 
ployment is chiefly referable to the coal which accompanies it. 
The essential part of the process by which these ores of iron are 
reduced, consists in decomposing them by the action of charcoal at 
high temperatures. The argillaceous iron of Wales, Shropshire, 4*c., 
is first roasted, and then smelted with lime-stone and coke : the use of 
the former being to produce a fusible compound with the clay of the 
ore, by which the latter is enabled to act upon the oxide, and to reduce 
it to the metallic state. 
726. The two oxides of iron form distinct salts with the acids. 
The salts containing the black oxide are of a green colour, mostly 
crystallizable, become reddish brown by exposure to air, and their 
Solutions absorb nitric oxide gas and become of a deep olive colour. 
The salts with the brown oxide do not, with very few exceptions, crys- 
tallize : they are brown, soluble in alcohol, and do not absorb nitric oxide. 
The alcalis precipitate hydrated oxides from these solutions. 
727. Iron and Chlorine unite in two proportions ; the chloride may 
be obtained by evaporating protomuriate of iron to dryness, and expos- 
ing the residuum to a red heat, out of the contact of air. A grey brit- 
tle lamellar substance is formed, consisting of one proportional of iron 
and one of chlorine ; 28 + 36. 
That the chlorine in the protochloride of iron is to that in the per- 
cliloride as 1 to J .5, is shown by Dr. Davy in his valuable paper on the 
chlorides, (Phil. Trans., 1812, 169.) and the equivalent number of 
iron, as deduced from his analysis, is somewhat above that here adopted. 
It must be confessed that the anomaly in the oxides and chlorides of 
iron throws some difficulty in the way of applying to them their equiva- 
lent numbers, but as the foundations of chemistry are purely experi- 
mental, we must not endeavour to do away that difficulty by a theoretical 
substitute. There is a difference in the relations of iron to oxygen and 
chlorine, compared with its relation to sulphur, which does not exist 
elsewhere ; of the cause of this difference we are at present ignorant. 
728. When iron wire is heated in chlorine, it burns with a red light, 
and produces a compound which rises in beautiful brown scales. It is the 
perchloride of iron, and consists of one proportional of iron, and one and 
a half of chlorine ; 28-J-S4. The chloride and perchloride of iron pro- 
duce protomuriaie and permuriate of iron when acted upon by water. 
729. Chlorate of Iron has not been examined. 
730. Muriate of Iron.—When iron filings are dissolved in muriatic 
acid, a greenish brown solution results, which contains a mixture of the 
protomuriate and permuriate. 
731. Protomuriaie of Iron is best obtained by digesting black sulphu* 
ret of iron in dilute muriatic acid ; sulphuretted hydrogen is evolved, 
and a green solution obtained, which, filtered and evaporated, yields 
pale green crystals, very soluble, and of a styptic taste. This salt 
abundantly absorbs nitric oxide gas ; the solution is of a very deep 
brown colour ; when heated, red oxide of iron falls and a portion of 
ammonia is formed ; a great part of the gas at the same time escapes. 
This salt may also be obtained by dissolving iron filings in muriati'e COMMON PYRITES. 
■acid excluded from air; but the above process is preferable, as the 
sulphuretted hydrogen prevents any part of the iron passing into the 
state of permuriate. 
732. Permuriate of Iron is formed by digesting the peroxide in mu- 
riatic acid : it dissolves without the evolution of chlorine, and when 
evaporated to dryness, furnishes a reddish brown deliquescent mass of 
a very astringent taste, soluble both in water and alcohol. It forms the 
basis of the tinctura ferri muriatis of the London Pharmacopoeia. 
Permuriate of iron is also formed by exposing the protomuriate to air ; 
<ind by acting upon it by nitric acid. Exposed to heat, muriatic acid, 
chlorine, and water are evolved, chloride of iron sublimes, and a por- 
tion of peroxide remains in the retort. 
733. When muriate of ammonia and peroxide of iron are mixed 
and exposed to heat in a proper subliming vessel, a yellow 
obtained, which is the ens veneris and fores martiales of old pharma- 
cy : the ferrum arnmoniatum of the present Pharmacopoeia; it con- 
sists chielly of muriate of ammonia, with a small but variable propor- 
tion of permuriate of iron. 
734. Iodine and Iron readily form a brown compound, fusible at a 
red heat, and which, when acted upon by water, forms a hydriodate of 
a green colour. 
735. Iodate of Iron has not been examined. 
736. The nitric acid dissolves the protoxide and peroxide of iron, 
and produces a green protonitrate and a red pernitrate. 
Nitric acid, diluted with a very little water, acts violently on iron 
and peroxidizes it, a vast quantity of gas being at the same time gene- 
rated, which consists of a mixture of nitrous and nitric oxides ; and a 
solution is formed of a reddish brown colour containing pernitrate of 
iron, and affording a brown precipitate to the alcalis. 
If the nitric acid be considerably diluted, (sp. gr. 1.16) the action is 
slow and very little gas escapes ; the solution acquires an olive brown 
colour from the nitric oxide Avhich it contains, but exposed to the air 
it becomes pale green in consequence of the escape of that gas. The 
alcalis produce a green precipitate in this solution : it cannot be ob- 
tained in crystals by the usual process, and passes into pernitrate by 
exposure to air. 
737. Sulphur and Iron.—There are two sulphurets of iron : the 
black sulphuret is composed of 28 iron -f- 16 sulphur; and the yellow 
sulphuret, or bi-sulphuret, of 28 iron + 32 sulphur. The former com- 
pound is produced by melting sulphur with iron filings ; it exists in 
nature under the name of magnetic pyrites: the bi-sulphuret is exclu- 
sively a natural product, very abundant, and called iron pyrites. 
.Magnetic pyrites is not found crystallized ; it is generally brown, or 
whitish yellow, and is not a common mineral. 
Common pyrites is found massive, and crystallized in a variety of 
forms ; its primitive form is the cube. It often occurs in nodules. 
Its colour is different shades of brass yellow. 
That the magnetic pyrites contains just half the proportion of sul- 
phur existing in the common pyrites was first shown by Mr. Hatchett. 
(Phil. Trans., 1804.) 
The principal use of pyrites is in the formation of green vitriol, for 
which purpose the ore is gently roasted and exposed to air and moisture. 
Some varieties are spontaneously decomposed, and furnish this salt. 
Pyrites has also lately been uSe.d in the production of sulphuric acid (325.) 222 
738. Sulphates of Iron.—The sulphuric acid with the protoxide of 
iron forms a protosulphate of iron, which crystallizes in green rhomboi- 
dal prisms, of a styptic taste, soluble in twice their weight of cold wa- 
ter, and insoluble in alcohol. This salt is called copperas or green vit- 
riol, and is often prepared by exposing roasted pyrites to moisture, in 
which case it is impure. It is usually formed by dissolving iron filings, 
or turnings, in dilute sulphuric acid, filtering and evaporating the solu- 
tion, and setting it aside to crystallize. It is also obtained, perfectly 
free from persulphate, by acting upon sulphuret of iron by dilute sul- 
phuric acid. It consists of one proportional of protoxide = 36 -f- I 
proportional of acid = 40, and in its crystallized state contains seven 
proportionals of water = 63. Its solution absorbs nitric oxide gas, and 
acquires a deep brown colour ; it also absorbs chlorine, muriatic acid 
is formed, and the iron becomes peroxidized, so that w’ater is here de- 
composed. 
Exposed to air and moisture, the protc.sulphate of iron gradually ab- 
sorbs oxygen, and is partly converted into a persulphate. It may also 
be converted into persulphate by nitric acid. When heated, it fuses 
in its water of crystallization, and at a high temperature evolves a mix- 
ture of sulphurous and sulphuric acids, peroxide of Iron remaining in 
the vessel: by this process sulphuric acid used formerly to be prepa- 
red, and the residue was known under the name of caput mortuum vit- 
rioli or colcothar. If the green crystals of this salt be exposed to a 
temperature of about 300°, they lose a portion of water, and crumble 
down into a white powder. 
739. Native Green Vitriol is frequently found associated with iron 
pyrites, being produced by its decomposition : it occurs in several of 
our coal mines. 
740. Persulphate of Iron is obtained by dissolving the moist red ox- 
ide in dilute sulphuric acid ; it does not crystallize, but affords, by 
evaporation, a brown deliquescent mass, consisting of 1 proportional 
of peroxide -J- 1.5 sulphuric acid, or 40 oxide + 60 sulphuric acid. 
It is formed in the mother waiters of the sulphate. Its taste is highly 
astringent, and when dry it becomes white : if in this state it be digest- 
ed in hot sulphuric acid, or if peroxide of iron, recently precipitated 
from the pernitrate, be boiled with excess of sulphuric acid, the solution 
yields octoedral crystals nearly white, and of a svreetish styptic taste : 
these are probably a bi-persulphate of iron. 
741. Phosphuret of Iron maybe formed by dropping phosphorus into 
a crucible containing red-hot iron wire ; it is a brittle grey compound, 
and acts upon the magnet. Upon the subject of the magnetic qualities 
of the sulphuret and phosphuret of iron, the reader is referred to Mr 
Hatchett’s analysis of the magnetical pyrites. (Phil. Trans., 1804). 
742. Phosplmtes of Iron.—These are both insoluble, and may be 
formed by adding solution of phosphate of soda, to protosulphate and 
persulphate of iron. The protophosphate of iron is of a pale blue co- 
lour ; the perphospate is white. 
743. Native Protophosphate of Iron occurs in the form of a blue earthy 
powder, and also in prismatic crystals. The former has sometimes 
improperly been termed Native Prussian Blue, and has been found in 
alluvial soil: the latter occurs with iron pyrites in Cornwall. 
744. Iron and Carbon.—The different kinds of cast iron and of steel 
contain more or less carbon, which materially affects their properties. 
The substance termed Phunbago, Graphite, or Black Lead, is generajlv 
IRON AND CARBON. PRUSSIAN BLgE. 
regarded as a true carburet of iron: this is not an uncommon mineral, 
though rarely found of sufficient purity for the manufacture of pencils : 
at Borrodale in Cumberland, where it occurs particularly pure, it Is in 
imbedded masses in slate and grauwacke: the coarser kinds and the 
dust, are melted with sulphur for common carpenters’ pencils: cruci- 
bles are sometimes made of it, and it forms an ingredient in composi- 
tions for covering cast-iron, and for diminishing friction in machines, 
According to Messrs. Allen and Pepys it consists of 
95 
5 
carbon 
iron 
100 
It may here he observed, that considerable difficulty attends the ac- 
curate analysis of compounds of carbon and iron, in estimating the pro- 
portion of the former; this has generally been indirectly effected by 
ascertaining the quantity of iron, and considering the loss of weight as 
carbon, a method obviously objectionable. If the action of dilute sul- 
phuric acid be resorted to, a portion of carbon is carried off by hydro- 
gen ; the same is the case with muriatic acid ; and if nitric acid be used, 
some carbonic acid may be formed, and artificial tannin is produced. 
Plumbago is infusible, and burns with great difficulty : its composi- 
tion was ascertained by the above-mentioned chemists, by exposing it 
in the apparatus used for burning the diamond, to a current of oxygen 
at a red heat, and ascertaining the quantity of carbonic acid and of ox- 
ide of iron thus produced. 
745. Carbonic Acid may be combined with the protoxide of iron, by 
adding carbonate of potassa to sulphate of iron ; a green precipitate of 
protocarbonate of iron falls, which, exposed to air, becomes brown, and 
evolves carbonic acid. Solution of bi-carbonate of potassa occasions a 
wrhite precipitate with sulphate of iron, part of which is re-dissolved on 
adding excess of the carbonated alcali. 
746. Spatkose Iron Ore is a native carbonate of iron, containing a lit- 
tle manganese and carbonate of lime. It occurs in Germany, and in 
some parts of Cornwall, crystallized in imperfect rhomboids. Its co- 
lour is yellowish, or brownish, grey. 
747. When hydrocyanate of potassa is added to the solutions of 
salts of iron, it occasions a bluish white precipitate in those containing 
the protoxide, and a blue precipitate in those containing the peroxide. 
The former precipitate is probably a ferrocyanate of iron, containing 
the protoxide ; the latter, a ferrocyanate containing the peroxide, and 
which has been long known under the name of Prussian Blue. 
745. Prussian blue is usually prepared by the follow ing process :— 
Equal parts of subcarbonate of potassa and some animal substance* 
such as dried blood, or horn shavings, are heated red hot, in a crucible, 
and six or eight parts of water are poured upon the mixture when it 
has quite cooled. The solution is filtered and found to contain hydro- 
cyanate of potassa, along with carbonate of potassa, and some other pro- 
ducts. It is mixed with a solution containing tw o parts of alum and one of 
sulphate of iron ; a precipitate falls, at fust of a dingy green hue, but 
which, by copious washings with very dilute muriatic acid, acquires a fine 
blue tint, and is called Prussian Blue, having been discovered by Diesbach 
a colour-maker of Berlin, in 1710. The first description of the mode 
of preparing it is given by Woodward in the Phil. Trans, for 1724. 
In this process, the animal matter is decomposed, and resolved into FEJtROO'ANATES OF AMMONIA. 
a variety of products arising from the reunion of its ultimate component 
parts. The matter remaining in the crucible contains cyanuret of po- 
tassium, and when acted upon by water, hydrocyanate of potassa, with 
a little carbonic acid and ammonia, is formed in consequence of the de- 
composition of a portion of the water ; and consequently the princi- 
pal salts contained in the washings of the black matter remaining in the 
crucible are carbonate and hydrocyanate of potassa, which, when ad- 
ded to a solution of sulphate of iron, form a precipitate of oxide and 
ferrocyanate of iron ; the former is removed by the dilute muriatic- 
acid. The aluminous earth of the alum gives a body to the precipi- 
tate, which improves it as a pigment. 
The above seems to be the simplest view of the formation and compo- 
sition of Prussian blue ; a variety of other opinions respecting its nature 
have been entertained,butthey require further experimental verification. 
749. Pure Prussian blue, obtained by adding ferrocyanate of potas- 
sa to solution of persulphate of iron, is a tasteless substance insoluble 
in water and alcohol. It is not acted upon by dilute nitric, sulphuric or 
muriatic acids, which renders it extremely improbable that it should be 
a hydrocyanate of iron, and strengthens the opinion of Mr. Porrett, 
that it is a ferrocyanate, or a compound of peroxide of iron with the 
peculiar acid mentioned below (752), and containing hydrogen, oxygen, 
iron, and cyanogen. 
750. When Prussian blue is boiled with potassa it is decomposed ; 
it loses its blue colour, oxide of iron is separated, and on filtering 
and evaporating the solution, a triple salt is obtained, consisting of hy- 
drocyanic acid, potassa, and oxide of iron ; this has been called triple 
prussiate of potassa, and ferrocyanate of potassa. It is best formed by 
adding powdered Prussian blue, previously heated with a dilute sul- 
phuric acid composed of one part of acid and five of water, and after- 
wards washed, to a hot solution of potassa, as long as its colour is de- 
stroyed. This salt forms permanent yellow cubic and tabular crystals, 
more soluble in hot than cold water, insoluble in alcohol, and of a pe- 
culiar taste. Boiled with dilute sulphuric or muriatic acids, hydrocy- 
anic acid is given out, and a precipitate formed similar to that which the 
salt produces in a solution of proto-sulphate of iron. It is decomposed 
in a retort at a red heat, hydrocyanic acid and ammonia are evolved, 
and the residue consists of charcoal, potassa, and iron. 
Exposed to a red heat in a platinum crucible, a brown mass is ob- 
tained, which, washed with water, deposits a grey cyanuret of plati- 
num. The aqueous solution furnishes, on evaporation, hydrocyanate 
of potassa and a large quantity of transparent colourless prismatic crys- 
tals.—Thenard, Traite, 2d edit., iii. 528. 
751. The ferrocyanalcs of ammonia, soda, lime, magnesia, baryta, 
and strontia, may be obtained by boiling those alcalis and earths with 
Prussian blue. 
752. Mr. Porrett (Phil. Trans., 1814.) considers the ferrocyanates 
as compounds of the respective bases, with an acid consisting of the 
elements of the hydrocyanic acid united to the protoxide of iron. 
This acid he terms ferrochyazic acid, derived from the initial letters of 
carbon, hydrogen, and azote. He obtained this acid dissolved in wa- 
ter, by adding to a solution of ferrocy anate of baryta just sulphuric 
acid enough to precipitate the baryta. It has a pale yellow colour, no 
smell, and is decomposed by a gentle heat or strong light, in which 
case hydrocyanic acid is formed, and white hydrocyanate of iron is deposited, which becomes blue by exposure. Gay-Lussac, obseiwing 
the production of the ferrocyanate of potassa by adding protoxide of 
iron to hydrocyanate of potassa, supposes that a portion of the hydro- 
cyanic acid is decomposed by the oxide, giving rise to a compound of 
cyanuret of iron with hydrocyanate of potassa. 
753. The following table shows the colours of the precipitates occa- 
sioned by solution of ferrocyanate of potassa, in different metallic 
solutions : 
FERROCYANATE OF POTASSA. 
METAL. 
SOLUTION. 
PRECIPITATE. 
MANGANESE 
Neutral protomuriate 
White 
IRON 
Neutral protosulphate 
White or pale blue 
Ditto 
Permuriate 
Prussian blue 
ZINC 
Muriate 
Yellowish white 
TIN ... 
Acid protomuriate 
White, then yellow and bluish 
Ditto j 
Acid permuriate 
Pale yellow 
CADMIUM . . ,| 
Muriate 
COPPER . . . .| 
Protomuriate 
Lilac 
Ditto j 
Pernitrate 
Deep brown 
LEAD | 
Nitrate 
White 
ANTIMONY . .1 
Tartrate of antimony and potassa 
0 
BISMUTH . . . 
Tartrate of bismuth and potassa 
0 
COBALT.... 
Muriate 
Pale green 
URANIUM . . . 
Sulphate 
Deep brown 
TITANIUM . ,| 
Acid muriate 
Deep blue (from acid 
Ditto j 
Neutral sulphate 
Sap Green 
CERIUM . . . ,| 
TELLURIUM .j | 
ARSENIC . . ,| 
White oxide 
Ditto | 
Arsenic acid 
NICKEL . . . . 
Sulphate 
Grey 
MERCURY . J 
Acid nitrate 
Greenish white 
Ditto 
Acid pernitrate 
Ditto 
Ditto 
Corrosive sublimate 
White 
RHODIUM - . 1 
PALLADIUM .| 1 
SILVER . . . . 
Nitrate 
Cream colour 
GOLD 
Muriate 
0 
PLATINUM . . 
Nitrate 
Yellow WROUGHT IRON. 
All the above precipitates appear to be ferrOcyanates, for when 
treated with solution of potassa, a ferrocyanate of potassa is obtained. 
754. Borate of Iron is of a yellow colour and insoluble. It is form- 
ed by adding borate of soda to sulphate of iron. 
755. The salts of iron are mostly soluble in water, and the solution 
is reddish brown, or becomes so by exposure to air. It affords a blue 
precipitate with ferro-cyanate of potassa ; and a black precipitate with 
hydrosulphuret of ammonia. Infusion of gall-nuts produces a black or 
deep purple precipitate. The hydriodic acid occasions no change. 
756. Of the alloys of iron, tin-plate is the only one of consequence. 
It is made by dipping clean iron plates into melted tin. The process 
is described at length by Mr. Parkes. (Quarterly Journal, Vol. viii. 
141.) When tin-plate is washed over with a weak acid, the crystalline 
texture of the tin becomes beautifully evident, forming an appearance 
which has been called moire metallique.—Quarterly Journal of Science, 
Vol. v. p. 368. 
757. An extremely important part of the chemical history of iron re- 
lates to the varieties of the metal which are found in commerce. These 
are much too numerous to be dwelt upon here ; so that we shall limit 
our observations to the principal of them only, which are cast iron, 
wrought iron, and steel. 
Of cast iron there are two principal varieties distinguished by the 
terms white and grey. The first is very hard and brittle, and, when 
broken, of a radiated texture. Acids act upon it but slowly, and exhi- 
bit a texture composed of a congeries of plates, aggregated in various 
positions.—Daniell, Quarterly Journal of Science and Arts, Vol. ii. p. 
280. 
Grey or mottled iron is softer and less brittle ; it may be bored, and 
turned in the lathe. When immersed in dilute muriatic acid, it affords 
a large quantity of black insoluble matter, which Mr. Daniell considers 
as a triple compound of carbon, iron, and silicium, and which has some 
very singular properties. The texture of the metal resembles bundles 
of minute needles. 
Cast iron is in this country converted into wrrought iron by a curious 
process, called puddling. The cast iron is put into a reverberatory 
furnace, and when in fusion is stirred, so that every part may be ex- 
posed to the air and flame. After a time the mass heaves, emits a blue 
flame, and gradually grows tough and becomes less fusible, and at length 
congeals. In that state it is passed successively between rollers, by 
which a large quantity of extraneous matter is squeezed out, and the 
bars are now malleable. They are cut into pieces, placed in parcels in 
a very hot reverberatory, and again hammered or rolled out into bars. 
They are thus rendered more tough, flexible, and malleable, but much 
less fusible, and may be considered as nearly pure iron. 
Analysis shows that cast iron contains oxygen, carbon, often sulphui 
and phosphorus, either silica or silicium, and it appears very probable 
that calcium exists in some of the varieties. 
By the processes of puddling and rolling, these substances are burned 
away or squeezed out, and thus malleability is conferred upon the me- 
tal by rendering it more pure. A specimen of cast iron analyzed by 
Berzelius afforded Iron 91.53—Manganese 4.57—Carbon 3.90. 
A bar of wrought iron, wrhen its texture is examined in the mode 
pointed out by Mr. Daniell, presents a fasciculated appearance, the fi- WOOTZ OR INDIAN STEEL. 
bres running in a parallel and unbroken course throughout its length. 
This structure may be well seen by tearing a bar of wrought iron 
asunder. 
758. Steel is a compound of iron with carbon, the proportions being 
variable. It combines the fusibility of cast with the malleability of 
bar iron, and when heated and suddenly cooled it becomes very hard, 
whence its superiority for the manufacture of cutting instruments. If 
kept for a long time in fusion, it loses carbon and becomes pure iron. 
Iron is converted into steel by a process called cementation, which 
consists in heating bars of the purest iron in contact with charcoal: it 
absorbs carbon and increases in weight, at the same time acquiring a 
blistered surface. This, when drawn down into smaller bars and beaten, 
forms tilted steel; and this broken up, heated, welded, and again drawn 
out into bars, forms shear steel. English cast steel is prepared by fusing 
blistered steel with a flux composed of carbonaceous and vitrifiable in- 
gredients, casting it into ingots, and afterwards, by and, 
carefully hammering, giving it the form of bars. 
759. Messrs. Stodart and Faraday found, that by intensely heating 
pure steel with charcoal powder, a carburet of iron, of a dark grey co- 
lour, very brittle and highly crystalline, was formed, which afforded, 
upon analysis, 
94.36 
5.64 
iron 
carbon 
100 
In this compound, which was frequently made and afforded the same 
results on analysis, and which therefore may be regarded as definite, 
the proportion of carbon very far exceeds that in steel, so that the lat- 
ter is probably a compound of pure iron with a variable proportion of 
the true carburet. 
760. The following table, drawn up by Mr. Mushet, shows the quan- 
tities of charcoal which disappeared during the conversion of iron into 
the different subcarburets of iron known in commerce.—Phil. Mag. 
xiii. : 
Charcoal absorbed. 
RESULTS. 
_1 
, . . soft cast steel 
, . . common cast steel 
_1 
. . . the same, but harder 
1_ 
SO 
. . . the same : too hard for drawing 
Jl 
, . . white cast iron 
A 
, . . mottled cast iron 
1 
5 0 
, . . black cast iron 
When the carbon amounts to -fo of the whole mass, the hardness is 
at a maximum. 
761. Wootz or Indian steel is truly valuable for the purpose of mak- 
ing edge tools. Its peculiar excellence is owing to combination with a 
minute portion of the earths alumina and silica; or rather, perhaps, 
with the bases of these earths. (Quarterly Journal of Science, vii., 
288.) Whether the earths are found in the ore, or are furnished by 
the crucible used in making the steel, is not certainly known : nor is TEMPERING. 
the Indian steel-maker probably aware of their presence. Wootz, in 
the state in which it is imported, is not fit to make into fine cutlery. It 
requires a second fusion, by which the whole mass is purified and equal- 
ized, and fitted for forming the finest edge instruments. 
762. The texture of steel, as exhibited by the action of an acid, is 
not fibrous, but appears somewhat lamellated. 
763. When steel is heated to a cherry-red colour, and then plunged 
into cold water, it becomes so extremely hard and brittle, as to be unfit 
for almost any practical purpose. To reduce it from this extreme 
hardness, is called by the workmen tempering, and is effected by again 
heating the steel to a certain point. The surface being a little bright- 
ened exhibits, when heated, various colours which constantly change 
as the temperature is increased, and by these colours it has been cus- 
tomary to judge of the temper of the steel. 
A more accurate as well as convenient method is to use a bath and 
thermometer ; the bath may be of mercury, or of the fusible mixture 
of lead, tin, and bismuth, or, indeed, of any fluid whose boiling point is 
not much under 600°. Into this bath the articles to be tempered are 
put, together with the bulb of a thermometer graduated to near the 
boiling point of mercury. The corresponding degrees at which the 
various colours appear are from 430° to 600°. The first change is at 
about 430°, but this is too faint to be distinguished, except by compari- 
son with another piece of untempered polished steel. At 460° the co- 
lour is straw, becoming deeper as the temperature is increased ; at 500° 
the colour is brown ; this is followed by a red tinge with streaks of 
purple, then purple, and at nearly 600° it is blue. 
The degrees at which the respective colours are produced being 
thus known, it follows that the workman has only to heat the bath, 
with its contents up to the required point. For example, suppose the 
blade of a penknife (or one hundred of them) to require tempering : 
they are suffered to remain in the bath until the mercury in the ther- 
mometer rises to 460°, and no longer, that being the heat at which the 
knife (supposing it to be made of the best English cast steel) will be 
sufficiently tempered. 
The advantages attending this method are obvious : the heat is 
equally applied to the whole ; and the workman, instead of attending to 
the colour of each blade,-has only to observe the thermometer. 
Some recent experiments, proving that steel, for certain uses, is 
sufficiently tempered long before it is heated to produce any change of 
colour, promise to give .additional value to this process by a thermom- 
eter. The knife edges attached to the pendulum described by Capt. 
Kater, Phil. Trans., 1818, p. 38.) were forged by Mr. Stodart, from a 
piece of fine wootz. They were carefully hardened, and tempered in the 
bath at 430° ; on trial they were found too soft. They were a second 
time hardened, and thenheated to 212°. The intention was to increase 
the heat from that point, trying the temper at the advance of about 
every ten degrees. In the present instance this was not necessary, the 
heat of boiling water proving to be the exact point, at which the knife 
edges were admirably tempered. 
It is highly probable that steel, for many uses, may be sufficiently 
tempered in a range so extensive as from 212° to 430°, and, by the 
thermometer, all the intervening degrees may certainly be ascertained. 
That, the colour produced on the surface of heated steel is the effect CHLORIDE of zinc. 
of oxidation, is proved from the circumstance that when steel is heated 
and suffered to cool under mercury or oil, none of the colours appear; 
nor do they when it is heated in hydrogen or in nitrogen. 
764. Steel is improved by combination with some other of the me- 
tals, forming valuable alloys. (See Silver.) They seem to require 
some difference in treatment from the workman, particularly in tem- 
pering.—Quarterly Journal of Science, Vol. ix. p. 319. 
Section X. Zinc. 
765. Zinc is found in the state of oxide and of sulphuret. It may be 
obtained pure by dissolving the zinc of commerce in dilute sulphuric 
acid, and immersing a plate of zinc for some hours in the solution, which 
is then filtered, decomposed by carbonate of potassa, and the precipi- 
tate ignited with charcoal in an iron or earthen retort. 
Common zinc generally contains a portion of lead, copper, iron, 
traces of arsenic and manganese, and a little plumbago : these impuri- 
ties remain in the form of a black powder when it is dissolved in dilute 
sulphuric acid. 
Zinc is a bluish white metal, specific gravity 7, malleable at 300°, 
hut very brittle when its temperature approaches that of fusion, which 
is about 680°. It is somewhat ductile, but its wire possesses little te- 
nacity. 
766. Oxide of Zinc is obtained by heating the metal exposed to air. 
At a red heat it takes fire, burns with a bright flame, and is converted 
into a white flocculent substance, formerly called pompholix, nihil album, 
philosopher'’s wool, and flowers of zinc. It consists of 34 zinc -f- 8 oxy- 
gen*. This oxide is white, tasteless, and soluble in the alcalis. As 
prepared by combustion it contains small particles of the metal, which 
always render it gritty ; hence, for pharmaceutical use, it is best pre- 
pared by precipitating solution of sulphate of zinc by ammonia, and 
washing and drying the precipitate. It is sometimes used as a pigment, 
both with oil and water ; and is employed in medicine as a tonic, and as 
an external application. 
767. The representative number of zinc was obtained by dissolving 
100 grains of pure zinc in nitric acid, evaporating to dryness and keep- 
ing the residue at a dull red heat till it ceased to lose weight: 122.75 
grains of oxide of zinc were thus obtained, and 22.75 : 100 : : 8 : 35.1. 
768. Chloride of Zinc is formed by heating leaf zinc in chlorine, or 
by evaporating muriate of zinc to dryness, and heating the residue red- 
hot in a glass tube. It is a fusible compound, very deliquescent, and 
produces a muriate of zinc by the action of.water. It does not rise at 
a red heat in close vessels. It consists of 35.5 zinc -f- 36 chlorine. 
It was formerly called butter of zinc. 
* This is deduced from Thomson’s late experiments (see Ann. Ph. vol. 17, for April 1821; 
as it has been shown elsewhere that 8 and not 7.5 is the representative number of oxygen, 
it follows that 33 (he number deduced from Brand’s data can not be correct,but if we merely 
substitute 8. for 7.5 : zinc will be 35 which docs not agree with the composition by Thom- 
son. The attraction of zinc for chlorine is very great, and this metal may 
therefore often be employed for separating chlorine from other combi- 
nations. 
769. Chlorate of Zinc crystallizes in octoedra, and is a very solu- 
ble salt. 
770. Muriate of Zinc is very soluble and difficultly cr}fstallizable : 
heated in the air it loses muriatic acid and leaves oxide of zinc : in a 
close vessel it loses water and leaves chloride of zinc. 
771. Iodine and Zinc readily combine, and produce a fusible, vola- 
tile, and crystalline compound, which, when exposed to air, deliques- 
ces into hydriodate of zinc. 
The iodide consists of 34 zinc + 125 iodine ; and the hydriodate 
may be regarded as consisting of one proportional oxide of zinc = 42 
+ one proportional hydriodic acid = 126. 
772. Iodate of Zinc.—When iodate of potassa is added to solution of 
sulphate of zinc, it forms an insoluble iodate of zinc. 
773. Nitrate of Zinc is a deliquescent salt, which crystallizes with 
difficulty in four-sided prisms. They are copiously soluble in water 
and alcohol, and consist of 
SULPHATE OF ZINC. 
42 
54 
oxide 
nitric acid 
96 
774. Liquid ammonia readily dissolves oxide of zinc, and even acts 
upon the metal. The concentrated solution of the oxide furnishes 
feathery crystals ; it is decomposed by the acids, and the immersion of 
a plate of copper causes a precipitation of part of the zinc, the ammo- 
nia, acquiring at the same time a blue colour.—De Lassone, Annales 
de Chirnie, xxxv. 53. 
775. Sulphuret of Zinc exists native under the name of Blende. It 
may be formed artificially by heating oxide of zinc with sulphur, and 
is then of a yellow brown colour. It consists of 34 zinc +16 sul- 
phur. 
Blende is a brittle soft mineral, of different shades of brown and 
black. Its primitive form is the rhomboidal dodecaedron. It usually 
contains traces of iron and lead. It is an abundant mineral, and im- 
portant as a source of the pure metal, which is obtained by roasting the 
ore, and afterwards exposing it to heat in proper distillatory vessels, 
mixed with charcoal (783). The English miners call it blackjack. 
776. Hyposidphite of Zinc was formed long ago by Fourcroy, wffio 
considered it as a sulphuretted sulphite. He formed it by digesting metal- 
lic zinc in sulphurous acid, sulphuretted hydrogen is disengaged, and 
by gentle evaporation crystals are obtained, which are to be digested 
in alcohol; this liquid dissolves the hyposulphite, and affords it in pris- 
matic. crystals. A mixture of oxide of zinc and sulphur treated by sul- 
phurous acid affords the same salt; it is efflorescent, and easily de- 
composed by heat.—Fourcroy, Systeme des connoissances Chymiques, v. 
380. 
777. Sulphite of Zinc is easily formed by dissolving the oxide in sul- 
phurous acid ; it is more easily crystallizable than the hyposulphite, 
and is insoluble in alcohol. 
778. Sulphate of Zinc.-—The metal is readily oxidized and dissolved BORATE OF ZINC. 
by dilute sulphuric acid, hydrogen gas is given off, and a transparent 
colourless solution of sulphate of zinc results, which, by evaporation, 
affords crystals in the form of four-sided prisms, terminated by four- 
sided pyramids. 
This salt is soluble in 2.5 parts of water at 60°. It consists of 1 
proportional of oxide = 42 -f- 1 proportional of acid = 40. Its crys- 
tals contain 7 proportionals of water = 63. Sulphate of zinc is pre- 
pared for the purposes of the arts from the native sulphuret, and is 
usually in the form of a white amorphous mass, called white vitriol. 
Native Sulphate of Zinc is found at Holywell in Flintshire, and in 
other places where the sulphuret of zinc occui’s ; it is probably the 
result of the decomposition of that ore. 
779. Phosphuret of Zinc is a brilliant lead-coloured compound. 
780. Neither Hypophosphite nor Phosphite of Zinc have been ex- 
amined. 
781. Phosphate of Zinc is not crystallizable. It may be obtained 
by dissolving zinc in phosphoric acid, and evaporation to dryness. A 
phosphate of zinc is also precipitated upon the addition of phosphate 
of soda to sulphate of zinc. These salts have not been precisely ex- 
amined, but it is probable there is a phosphate and a bi-phosphate of 
zinc. 
782. Carbonate of Zinc occurs native, forming one of the varieties 
of the mineral called calamine. It may be formed by adding carbonate 
of potassa to sulphate ol zinc. It consists of 42 oxide of zinc -j- 22 
carbonic acid = 64. It is white and tasteless. 
The primitive form of calamine, which occurs both crystallized and 
massive, is an obtuse rhomboid. It is often found investing carbonate 
of lime, which has sometimes been decomposed, and the calamine re- 
mains in pseudo-crystals. This mineral abounds in Somersetshire, 
Flintshire, and Derbyshire. A beautiful variety, coloured by carbo- 
nate of copper, is found at Matlock. A variety of calamine, contain- 
ing siliceous earih, is known by the name of electric calamine, from its 
property of becoming electrical when gently heated. 
783. The zinc of commerce is procured from the native sulphuret 
and from calamine by the following process. The ore is first picked 
and broken into small pieces, and then submitted to a dull red heat in 
a reverberatory furnace, by which carbonic acid is driven off from the 
calamine, and sulphur from the blende. It is then washed, ground, 
and thoroughly mixed with about one eighth its weight of powdered 
charcoal. This mixture is put into large earthen pots, not unlike oil 
jars, six of which are usually placed in a circular furnace ; each pot 
has an iron tube passing from its lower part, through the floor of the 
furnace, and dipping into water ; they are every where else firmly 
luted : upon the application of a red heat, the metal distils through the 
tube into the water beneath, whence it is collected, melted, and cast 
into cakes. 
784. Borate of Zinc is an insoluble white powder. 
785. Ferrocyanate of potassa produces a yellowish white precipitate 
in solutions of zinc. 
786. The salts of zinc are mostly soluble in water, and the solutions 
are colourless and transparent: they are not precipitated by hydriodir 
acid. Potassa, soda, and ammonia, form white precipitates, soluble in 
excess of the alcali, and sulphuric acid. Hydrosulphuret of ammonia NATIVE OXIDE OF TIN. 
produces a yellowish white precipitate. The soluble phosphates, 
carbonates, and borates, produce white precipitates. 
787. Alloys of Zinc.—With potassium and sodium zinc forms brittle 
alloys, decomposable by exposure to air and water. Its alloy with 
manganese is unknown. With iron it forms a white and somewhat mal- 
leable alloy, which is difficult to form ; but if plates of hot iron be dip - 
ed into melted zinc, they acquire the appearance of tin-plate. 
Section XI. Tin. 
788. This metal has been known from the remotest ages. It was 
in common use in the time of Moses, and was obtained at a very early 
period from Spain and Britain, by the Phoenicians.—Pliny, lib. iv. cap. 
34, and xxxiv. cap. 47. 
The native oxide is the principal ore of tin ; the metal is obtained 
by heating it to redness with charcoal. The process is described at 
length in Aikin’s Dictionary, (Art. Tin.) 
Tin has a silvery white colour ; it is malleable, though sparingly 
ductile. Specific gravity 7.30. It melts at 440°, and by exposure to 
heat and air is gradually converted into a white peroxide. Placed upon 
ignited charcoal under a current of oxygen gas, it burns very bril- 
liantly. 
789. A preparation under the name of powdered tin is sometimes 
directed to be prepared for pharmaceutical use, by shaking the melted 
metal in a wooden box rubbed with chalk on the inside : tin filings have 
also a place in some Pharmacopoeia, and have been used as a vermifuge. 
These preparations are, however, both dangerous, the metal being 
rendered poisonous in the former case by slight oxidation, (Orfila, 
Trait€ des Poisons, T. i. 2me partie, p. 18.) and often creating very 
dangerous irritation when given in filings. 
790. Protoxide of Tin is obtained by precipitating protomuriate of 
tin by ammonia ; it falls in the state of hydrate ; when dried, it is of a 
grey colour, and undecomposable by heat. It dissolves in the alcalis ; 
exposed to heat and air it passes into the state of peroxide, undergoing 
a faint combustion. Its ammoniacal solution, when long kept, deposits 
metallic tin in arborescent crystals, and becomes a solution of the pe- 
roxide. 
791. Peroxide of Tin is formed by treating the metal with nitric acid : 
there is a violent action attended by the formation of nitrate of ammo- 
nia. (287). Scarcely any of the metal is dissolved, but remains as a 
yellowish powder, which may be purified by washing. It is also form- 
ed by heating tin filings with red oxide of mercury ; and by projecting 
a sufficient quantity of nitre upon red-hot tin. This oxide dissolves in 
the alcalis. Fused with glass it forms White Enamel. Heated intensely 
it becomes insoluble in acids, and undergoes fusion. 
The substance called Tin Putty, is an oxide of tin formed by levigat- 
ing the crusts of oxide that form upon the metal when kept for some 
time in fusion. 
792. Native Oxide of Tin is found in Cornwall; in Spain; and in PROTOMURIATE OF TIN. 
233 
Saxony : it has also been found in Brittany, in France ; in the East In- 
dies ; and in South America. The specific gravity of the native oxide 
is 7 : Its primitive crystal is an obtuse octoedron, of which the modifi- 
cations are extremely numerous. (W. Phillips, Geological Transac- 
tions, Vol. ii.) In some of the valleys of Cornwall, tin is found in 
rounded nodules, of various sizes, mixed with pebbles and rounded 
fragments of rocks. To separate the tin from the alluvial matter, cur- 
rents of water are passed over it, and hence these deposits have been 
called stream works, and the tin ore, stream tin. One of the most ex- 
tensive of these is a branch of Falmouth Harbour. 
A modification of stream tin is called wood tin. It usually appears in 
small banded fragments of globular masses. 
793. The number representing tin is 59. The protoxide consists of 
59 tin -J- 8 oxygen. The hydrate of G7 protoxide -f- 9 water ; and the 
peroxide of 59 tin + 16 oxygen. These numbers are deduced from 
the accurate analyses of Dr. John Davy [Phil. Trans. 1812) and M. 
Gay-Lussac. (Annales de Chimie, lxxx.) The protoxide of tin, accord- 
ing to both these chemists, consisting of 100 tin -f- 13.5 oxygen ; and 
the chloride, according to John Davy, of 100 tin -{- 60.71 chlorine. 
794. Chloride of Tin is procured by heating together an amalgam of 
tin and calomel; or more simply by heating protomuriate of tin in a re- 
tort till it fuses ; it is a grey semi-transparent crystalline solid, which 
dissolves in water, forming a protomuriate of tin ; it is volatile at a red 
heat; it consists of 59 tin + 36 chlorine. Heated in chlorine it burns 
into perchloride of tin. 
795. If tin be heated in chlorine, or if amalgam of tin be distilled 
with corrosive sublimate, a perchloride is obtained. The best propor- 
tions are six parts of tin, previously combined with one of mercury, and 
intimately mixed with thirty of corrosive sublimate. The mixture is 
put into a glass retort with a sufficiently capacious receiver luted to it, 
and may de distilled over a small charcoal fire. The heat should be 
slowly raised to prevent too sudden action. Towards the end of the 
process a little chloride rises, which the old chemists,, from its consis- 
tency and appearance, called Butter of Tin. It is a transparent colour- 
less fluid, and when poured into water, is instantly converted into per- 
muriate of tin. It consists of 59 tin + 72 chlorine. It was formerly 
called Libavius’s Fuming Liquor: it exhales copious fumes when ex- 
posed to a moist air, and produces muriatic acid and oxide of tin. It is 
instantly decomposed by metallic zinc, forming chloride of zinc and a 
precipitate of metallic tin. 
796. Chlorate of Tin has not been examined. 
797. The Protomuriate of Tin, used by dyers, may be obtained by 
boiling one part of tin with two of muriatic acid. This solution quick- 
ly absorbs oxygen from the air and from several compounds, and if ad- 
ded to certain metallic solutions, revives or deoxidizes them. With 
solution of gold it produces a purple precipitate used in painting porce- 
lain, and known under the name of Purple of Cassius. It crystallizes 
from its concentrated solution in small deliquescent needles. With 
infusion of cochineal it produces a purple precipitate. This muriate 
of tin is the Sal Jovis of old writers, Jupiter being the name by which 
the alchymists distinguished this metal. 
When potassa is added to muriate of tin, a submuriate of the pro- 
toxide is thrown down, containing, according to J. Davy>t SULPHATE OF TIN. 
70.4 protoxide 
19 muriatic acid 
10.6 water 
100.0 
798. The Permuriate of Tin (muriate containing the peroxide) may 
be formed by dissolving the metal in nitro-muriatic acid, or by expos- 
ing the muriate to air. It forms acicular crystals in the upper parts of 
phials containing the bi-chloride imperfectly secured from air ; and is 
directly formed by adding water to the bi-chloride, which excites much 
heat, and forms a concrete mass easily fusible and soluble in water. It; 
does not occasion precipitates in the metallic solutions, and produces a 
scarlet colour with infusion of cochineal. 
799. The pure alcalis added to this salt of tin, occasion a precipitate 
which has not been accurately examined, but is said to be a subpermu- 
riate. The peroxide of tin is more readily soluble in alcalis than the 
protoxide ; it has been hence termed Stannic Acid. 
800. Iodide of Tin may be formed directly by heating the metal with 
iodine ; or indirectly by adding hydriodic acid to a solution of muriate 
of tin. It is an orange-coloured compound, and has not been analyzed. 
801. lodate of Tin has not been examined. 
802. Nitrate of Tin may be formed by acting upon the metal by di- 
lute nitric acid ; a yellow solution which will not crystallize is obtain- 
ed ; exposed to air it absorbs oxygen, and peroxide of tin precipitates. 
If evaporated the peroxide falls, and a portion of nitrate of ammonia is 
formed. It is evident therefore that part of the water, as well as of 
the acid, are here decomposed. 
803. Tin and Sulphur.—There are two sulphurets of tin. That con- 
taining 1 proportional of metal -{- 1 of sulphur, may be procured by 
heating tin with sulphur ; it is of a deep bluish colour and crystallizes 
in long needles. 
804. Bi-sulphuret of Tin is of a bright golden yellow colour, and flaky 
structure, and has been termed Aururn Musivum. It is formed by 
heating peroxide of tin with its weight of sulphur. Mr. Woulfe has 
given a formula for its production, (Phil. Trans., 1771) but the follow- 
ing, taken from the London New Dispensatory of 1765, answers best. 
Take 12 oz. of tin and amalgamate it with 6 oz. of mercury, reduce it 
to powder, and mix it with 7 oz. of flowers of sulphur and 6 oz. of sal 
ammoniac and put the whole into a glass matrass placed in a sand heat. 
Apply a gentle heat till the white fumes abate, then raise the heat to 
redness, and keep it so for a due time. On cooling and breaking the 
matrass, the Mosaic gold is found at the bottom.—See Woulfe's Paper, 
and Aikin’s Diet.: Art. Tin. 
The sulphurets of tin consist respectively of 59 tin -f- 16 sulphur, 
and 59 tin -f- 32 sulphur. 
805. Hyposulphite of Tin, has not been examined. Muriate of tin 
forms no precipitate with the alcaline hyposulphites. 
806. Sulphite of Tin is formed by digesting the protoxide in sulphu - 
rous acid, but the salt has not been examined. 
807. Sulphate of Tin.—When tin is boiled in sulphuric acid, a solu- 
tion is obtained which deposits white acicular crystals. A protosul- 
phate of tin is also precipitated by pouring sulphuric acid into proto- 
muriate of tin. CADMIUM. 
235 
808. Hydrosulphuretted Oxide of Tin is yellow brown, and formed 
by pouring solution of sulphuretted hydrogen into dilute muriate of 
tin. 
809. Phosphuret of Tin may be formed by dropping phosphorus into 
melted tin. It is of a silvery colour, sectile, and somewhat ductile. 
When its filings are sprinkled upon hot coals the phosphorus burns. 
810. Phosphite of Tin has not been examined. 
811. Phosphate of Tin is formed by adding phosphate of soda to the 
solutions of tin. It is a white powder, not soluble in water, and fuses 
at a red heat into an opaque white enamel. 
812. Carbonate of Tin.—When carbonate of potassais added to pro- 
tomuriate of tin, a white precipitate ensues, which, when washed and 
dried, effervesces copiously with the acids. 
813. Borate of Tin is an insoluble white powder. 
814. Ferrocyanate of potassa produces a white precipitate in solu- 
tion of muriate of tin. 
815. The salts of tin are mostly soluble in water. They are pre- 
cipitated, of an orange colour by hydriodic acid, and by hydrosulphu- 
ret of ammonia, provided no excess of acid be present. Solution of 
muriate of gold, and of corrosive sublimate produce purple and black 
precipitates in the salts of tin containing the protoxide, but none in those 
containing the peroxide. 
816. Alloys of Tin.—With potassium and sodium tin forms brittle 
white alloys. Its alloy with manganese is not known. It does not rea- 
dily combine with iron, but tin-plate (756) may be considered as an im- 
perfect alloy of those metals. With zinc it forms a hard brittle alloy. 
Section XII. Cadmium. 
817. This metal is contained in certain ores of zinc, and especially 
in the black fibrous Blende of Bohemia. It may be procured by di- 
gesting the ore in muriatic acid, by which a mixed muriate of zinc and 
cadmium is obtained : it should be evaporated to dryness, and re-dis- 
solved in water. If cadmium be present, the solution affords a bright 
yellow precipitate with sulphuretted hydrogen ; and upon immersing 
into it a plate of zinc, metallic cadmium is precipitated, which may be 
fused into a button in the usual way. 
The simplest method of detecting cadmium is the following, devised 
by Dr. Wollaston. Digest the ore in muriatic acid, filter, and evapo- 
rate to dryness : re-dissolve the dry mass in water, filter, and put a 
cylinder of iron into the clear solution to precipitate all metals thus se- 
parable ; filter again, and immerse a cylinder of zinc, which will throw 
down metallic cadmium, and which, when re-dissolved in muriatic acid 
exhibits its peculiar characters. 
818. The physical properties of cadmium closely resemble those of 
tin : its specific gravity is 8.63. It fuses and volatilizes at a tempera- 
ture a little below that required by tin. Air does not act upon it exr 
cept when heated, when it forms an orange-coloured oxide, not vola- 
tile, and easily reducible. COPPER AND OXYGEN. 
819. Oxide of Cadmium readily dissolves in acids ; it is precipitated 
by potassa in the state of a white hydrated oxide, soluble in ammonia. 
Sulphuretted hydrogen forms a yellow precipitate in the solution of 
cadmium, and zinc throws down metallic cadmium. 
From the experiments of Mr. Children, it appears that the oxide 
contains 
Cadmium 88 
Oxygen 8 
Consequently, the representative number of the metal will be 88. 
The other compounds of cadmium have scarcely been examined*. 
Section XIII. Copper. 
820. This metal is found native, and in various states of combina- 
tion. Of its ores, the oxide, chloride, sulphuret, sulphate, phosphate, 
carbonate, and arseniate, are the most remarkable. The metal may be 
obtained perfectly pure by dissolving the copper of commerce in mu- 
riatic acid ; the solution is diluted, and a plate of iron is immersed upon 
which the copper is precipitated. It may be fused into a button, after 
having been previously washed in dilute sulphuric acid to separate a 
little iron that adheres to it. 
It was known in the early ages of the world, and was the principal 
ingredient in domestic utensils, and in the instruments of war, previous 
to the discovery of malleable iron. The word copper is derived from 
the island of Cyprus, where it was first wrought by the Greeks. 
821. Copper has a fine red colour and much brilliancy ; it is very 
malleable and ductile, and has a peculiar smell when warmed or rub- 
bed. It melts at a cherry red or dull white heat. Its specific gravity 
is 8.89. Under a flame, urged by oxygen gas, it takes fire, and burns 
with a beautiful green light. 
822. Exposed for a long time to damp air, copper becomes covered 
with a thin greenish crust of carbonate. If heated and plunged into wa- 
ter, a quantity of reddish scales separate, consisting of an imperfect 
oxide. The same scales fly oft' during cooling from a plate of the me- 
tal w'hich has been heated red hot. 
823. Native Copper occurs in a variety of forms ; massive, dendritic, 
granular, and crystallized in cubes, octoedra, 4*c. It is found in Corn- 
wall, Siberia, Saxony, Hanover, Sweden, and America ; chiefly, but 
not exclusively, in primitive rocks. 
824. Copper and Oxygen.—There are two oxides of copper. The 
red or Protoxide occurs native. It may be formed artificially, by di- 
gesting a mixture of metallic copper, and peroxide of copper, in mu- 
riatic acid. When potassa is added to this solution, a hydrated protox- 
ide, of an orange colour, falls ; if quickly dried out of the contact of 
* In a subsequent part of this work Brande gives the atom of Cadmium = 52.3 which 
equivalent he also introduces into his tables, see article Cadmium, section xii. and the tables. 
This 52.3 requires to be altered to 55.8 (nearly) so as to be proportional to 3 oxygen, instead 
of 7.5. PERCHLORIDE OF COPPER, 
237 
i-ar, it becomes of a red brown : it consists of 64 copper + 8 oxy- 
gen = 72. 
825. The Native Protoxide, or Ruby Copper, is of a red or steel-grey 
colour, soft and brittle, and occurs massive, and crystallized in octoedra, 
dodecaedra, and cubes. There is a beautiful variety in tine capillary 
crystals ; and another, which is compact and earthy, called Tile Ore. 
Cornwall abounds in fine specimens of this ore. 
826. Peroxide of Copper is procured by precipitating nitrate of cop- 
per by potassa, washing the precipitate and exposing it to a red heat. 
It is black, and consists of 64 copper -f- 16 oxygen = 80. 
827. The composition of this oxide is learned by dissolving 100 
grains of pure copper in nitric acid, evaporating to dryness, and giving 
the residue a red heat in a porcelain crucible ; it is peroxide of cop- 
per, and weighs 125 grains : considering this as a compound of 1 pro- 
portional of copper and 2 of oxygen, the number 64 will represent the 
metal; for, 25 : 100 : : 16 : 64. 
100 grains of pure native protoxide of copper in octoedral crystals, 
dissolved in muriatic acid, furnished a precipitate of 89 grains of me- 
tallic copper upon a plate of iron, so that the protoxide consists of 89 
copper 4-11 oxygen; and 11 : 89 : : 8 : 64.7. 
This number closely accords with that derived from the analysis of 
the chloride. 
828. Copper and Chlorine.—Gaseous chlorine acts upon copper with 
great energy, and produces two chlorides ; the one a fixed fusible sub- 
stance, which is the protochloride, consisting of 1 proportional of cop- 
per = 64 1 proportional of chlorine = 36. The other a volatile 
yellow substance, which is a perchloride, and contains 64 copper 4* 
72 chlorine. 
829. The Protochloride of Copper was first described by Boyle in 
1666, under the name of Rosin of Copper. It may be obtained by ex- 
posing copper filings to the action of chlorine not in excess ; or by 
evaporating the protomuriate, and heating the residue in a vessel with 
a very small orifice ; or by heating the perchloride in the same way. 
It is also the residue of the distillation of a mixture of two parts of cor- 
rosive sublimate and one of copper filings. It is insoluble in water, 
but soluble in muriatic acid, from which potassa throws down a pro- 
toxide. When water is added to its muriatic solution it is precipitated 
unaltered ; its colour varies, being generally dark brown ; but if fused 
and slowly cooled, it is yellow, translucent, and crystalline. 
830. When moistened chloride of copper is exposed to air it ac- 
quires a greenish white colour, and becomes converted into a subper- 
muriate of copper. The same compound may be formed by adding hy- 
drated peroxide of copper to a solution of the permuriate ; or by ex- 
posing to the atmosphere slips of copper partially immersed in muria- 
iic acid. This compound consists of 
2 proportionals peroxide of copper 80 X 2 
= 160 
1 muriatic acid 
. . 37 
18 
215 
831. Perchloride. of Copper may be formed by dissolving peroxide 
of copper in muriatic acid, and evaporating to dryness by a heat below NITRATE OF COPPER. 
400°. it is soluble in water, producing a permuriate,. from which 
potassa precipitates the peroxide : its colour is yellow, but it becomes 
white and afterwards green when exposed to heat and moisture. Ex- 
posed to a red heat in a tube with a very small orifice, gaseous chlorine 
is expelled and it becomes a protochloride. 
832. Muriatic acid acts with difficulty on metallic copper, except it 
be concentrated and boiling ; but it readily dissolves the peroxide, 
forming a brown or grass-green solution, according to its state of dilu- 
tion. This is a permuriate of copper. If plates of copper be exposed 
to the joint action of air and the fumes of muriatic acid, they become 
incrusted with a green powder, which is readily soluble in muriatic 
acid, and which may be termed a subpermuriate. (830.) 
If metallic copper be digested in muriatic acid with the peroxide, an 
olive-coloured solution of protomuriaie of copper is formed which 
strongly attracts oxygen, and which when concentrated deposits small 
grey crystals. The addition of potassa occasions a precipitate of the 
orange or protoxide of copper, (824) which according to Berzelius, 
consists of 100 copper -f- 12.5 oxygen. (Annales de Chim., lxxviii. 
107.) Proust’s analysis of the peroxide gives 100 copper -f* 25 oxygen, 
and these numbers furnish 64 as the equivalent of copper. (827.) 
833. Native Submuriate of Copper is found in Peru and Chili, 
sometimes in the form of green sand, and sometimes massive and crys- 
tallized. The green sand was found in the river Lipas, in the desert 
of Atacama, separating Peru from Chili, hence mineralogists have 
termed this variety, Atacamite. Muriate of copper has also been 
found upon some of the lavas of Vesuvius. The primitive form of 
this substance is an octoedron. It is of a deep green colour, and con- 
tains, according to Dr. Davy’s analysis, 
73 
16.2 
10.8 
peroxide of copper 
muriatic acid 
water 
100 
834. Chlorate of Copper is a blue-green deliquescent salt, dilliculth 
crystallizable, formed by dissolving peroxide of copper in chloric 
acid. A piece of paper dipped into its solution burns with a remark- 
ably green flame.—Vauquerin. 
835. An Iodide of Copper is precipitated from solutions of the metal 
by hydriodic acid. It is brown and insoluble. 
836. When solution of iodate of potassa is added to solutions of cop- 
per, an insoluble iodate of copper is thrown down. 
837. Nitrate of Copper.—Nitric acid, diluted with three parts of 
water, rapidly peroxidizes copper, evolving nitric oxide, and forming a 
bright blue solution, which affords deliquescent prismatic crystals on 
evaporation, of a tine blue colour and very caustic. It consists of 80 
peroxide + 108 acid ; but the crystals contain a considerable portion 
of water, which causes them to liquefy at a temperature below 212°. 
At a higher temperature they lose water and acid, and according to 
Proust become a sub pernitrate, which is insoluble in water, and entire- 
ly decomposed at a red heat. There appears to be no protonitrate of 
copper, for protoxide of copper, digested in very dilute nitric acid is 
resolved into peroxide which dissolves, and into metallic copper. Po- COPPER PYRITES. 
iassa forms, in this solution, a bulky blue precipitate of hydrated per- 
oxide of copper, which, when boiled in potassa or soda, becomes black 
from the loss of its combined water. 
838. When crystals of nitrate of copper are coarsely powdered, 
sprinkled with a little water, and quickly rolled up in a sheet of tin- 
foil, there is great heat produced, nitrous gas is rapidly evolved, and 
the metal often takes fire. 
839. If ammonia be added to solution of nitrate of copper, it occa- 
sions a precipitate of the hydrated peroxide ; but if it be added in ex- 
cess, the precipitate is re-dissolved, and a triple ammonio-nitrate oj 
copper is produced 
840. If peroxide of copper be digested in ammonia it is dissolved, 
forming a bright blue solution, which by careful evaporation affords 
fine blue crystals. A mixture of lime, sal ammoniac, and water, placed 
in a copper vessel, or mixed with oxide of copper, also affords a fine 
blue liquor in consequence of the action of the ammonia on the oxide 
of copper. This solution is the Aqua Sapphirina of old pharmacy. 
The compound has sometimes been called Ammoniuret of Copper, or 
Cuprate of Ammonia. 
841. The protoxide of copper also dissolves in ammonia, but the so- 
lution is colourless ; if it be exposed to air it becomes blue. This may 
be well shown by filling a tall glass with liquid ammonia, and adding a 
few drops of solution of protomuriate of copper; the liquid presently 
acquires a blue colour upon the surface, but remains for some time co- 
lourless below. 
842. Plates of copper digested in a solution of muriate of ammonia, 
are soon incrusted with a green powder, which has been used in the 
arts under the name of Brunswick green. 
843. Copper and Sulphur.—There are two sulphurets of copper, 
both of which exist native ; the one is black, and may be formed arti- 
ficially, by heating a mixture of copper filings and sulphur : as soon as 
the latter melts a violent action ensues, the copper becomes red hot, 
hydrogen escapes, and a black brittle body is formed, consisting of 64 
copper -f- 16 sulphur*. 
The hi-sulphuret is a common ore of copper, called pyrites. It con- 
sists of 64 copper -f- 32 sulphur, and is of a golden yellow colour. 
844. The Native Black Sulphuret of Copper is principally found in 
primitive countries. In England, it occurs in great beauty, crystalliz- 
ed and massive, in Cornwall, and in Yorkshire. Its colour is grey ; its 
lustre shining and metallic, and it yields easily to the knife. Its primi- 
tive form is a six-sided prism, which passes into the dodecaedron with 
triangular faces, and various modifications of it. 
A variety of black sulphuret of copper, containing iron and arsenic, 
has been described by Messrs. W. and R. Phillips. It has been term- 
ed by the latter Tennantite; its most ordinary form is the rhomboidal 
dedocaedron, either perfect or variously modified.—Quarterly Journal 
of Science and Arts, Vol. vii., p. 95. 
845. Copper pyrites, or the yellow sulphuret of copper, is the most 
important and generally occurring ore, from which the largest propor- 
tion of the copper of commerce is derived; it occurs in a variety of 
* The hydrogen appears to be derived from the sulphur. (343.; blue Vitriol. 
forms, its primitive crystal being the regular tetraedron. The Cornish 
mines are very productive of this ore, and it is the principal product of 
of the Parys mountain mine in Anglesea. A beautiful iridescent varie- 
ty occurs in the Ecton mine in Staffordshire. 
846. The following is an outline of the process by which these ores 
of copper are reduced, as carried on upon a very large scale near 
Swansea, where the chief part of the Cornish ores are brought to the 
state of metal. The ore, having been picked and bi’oken, is heated in 
a reverberatory furnace, by which arsenic and sulphur are driven off. 
It is then transferred to a smaller revei'beratory, where it is fused, and 
the slag which separates, being occasionally removed, is cast into oblong 
masses used as a substitute for bricks. The impure metal collected at 
the bottom of the furnace is granulated by letting it run ixxto water; it 
is afterwards re-melted and granulated two or three times successively, 
in order fui'ther to separate impurities, which are chiefly sulphur, iron, 
and arsenic, and ultimately cast into oblong pieces called pigs, which 
are broken up, roasted, and lastly melted with a portion of charcoal in 
the refining furnace. It is now malleable : and is generally rolled into 
plates, which are annealed, and when hot, quenched in urine, which, 
gives the metal a peculiar red tinge. 
847. Hyposulphite of Copper was formed by Mr. Herschel by mixing 
hyposulphite of potassa witli sulphate of copper. It is colourless ; of 
an intensely sweet taste ; and provided air be excluded, it is not turned 
blue by ammonia, which seems to show that the metal is in the state of 
protoxide.—Edinburgh Philosophical Journal, i. 24. 
848 Sulphite of Copper may be obtained by passing sulphurous acid 
into water through which oxide of copper is diffused. Small red crys- 
tals are formed, composed of protoxide of copper and sulphurous acid. 
—Chevreuil, Annales de Chimie, lxxxiii. 
849. When sulphite of potassa is added to nitrate of copper a preci- 
pitate falls, which assumes the form of red and yellow cx*ystals. The 
former are sulphite of copper; the latter a tripple sulphite of potassa 
and copper.—Chevreuil. 
850. Persulphate of Copper—Roman Vitriol—Blue Vitriol.—This- 
salt is formed by dissolving peroxide of copper in sulphuric acid. It 
crystallizes in rhomboidal prisms of a fine blue colour, doubly refrac- 
tive, and soluble in about 4 parts of water at 60°. It may also be form- 
ed by boiling copper filings in sulphuric acid ; a process which fur- 
nishes abundance of sulphurous acid, but which is not generally had re- 
course to, to produce sulphate of copper. It is made upon a large 
scale, by exposing roasted sulphuret of copper to air axid moisture. 
When heated it loses water of crystallization, and at a higher tempera- 
ture sulphuric acid is evolved, unmixed with sulphurous acid, as in the 
case of the decomposition of protosulphate of iron (738), and peroxide 
of copper remains. It is the Vitriol or Salt of Venus of the alchymists. 
It consists of 80 peroxide + 80 sulphuric acid ; when crystallized it 
contains 10 proportionals of water, and consequently its composition 
will stand thus :— 
1 proportional of peroxide 
. 80 
2 proportionals of sulphui'ic acid . 
. 80 
10 proportionals of water 
, 90 
250 CARBONATE of copper. 
241 
There appears to be no protosulphate of copper, for when protoxide 
of copper is digested in dilute sulphuric acid, metallic copper is se- 
parated, and a solution of the peroxide obtained. 
851. By cautiously adding ammonia to a solution of the foregoing 
salt, a subsulphate of copper is precipitated, consisting of 160 oxide -j- 
40 acid. The alcalis precipitate hydrated peroxide from the solution 
of the persulphate, and excess of ammonia forms a triple sulphate of 
ammonia and copper. The same compound is formed by triturating 
carbonate of ammonia with crystals of sulphate of copper. It is the 
cuprum ammoniatum of the Pharmacopoeia. 
852. Sulphate of Copper and Potassa is a triple salt formed by digest- 
ing peroxide of copper in bisulphate of potassa. It crystallizes in 
rhomboids of a pale blue colour. 
853. Phosphorus and Copper form a grey brittle phosphuret. It is 
most easily made by dropping pieces of phosphorus on red-hot copper 
wire. It is more fusible than copper. 
854. Neither the hypophosphite nor phosphite of copper have been 
examined. 
855. Phosphate of Copper may be formed by mixing solution of sul- 
phate of copper with phosphate of soda ; it is a-bluish green insoluble 
powder, composed, as would appear from Mr. Chenevix’s analysis, 
{Phil. Trans,. 1803.) of 
1 proportional peroxide of copper 
80 
2 phosphoric acid . . 
56 
1 water 
9 
145 
856. Native Phosphate of Copper has been found near Cologne. It 
is of a green colour, and forms small rhomboidal crystals. 
857. Carbonate of Copper, artificially prepared, by adding carbo- 
nate of potassa to sulphate of copper and drying the precipitate, is a 
green compound, insoluble in water, consisting, according to Mr. R. 
Phillips, of 80 peroxide 4* 22 carbonic acid 9 water. It is, there- 
fore, a subpercarbonate. Copper, exposed to damp air, becomes in- 
crusted with this compound. Exposed to heat, it loses water and car- 
bonic acid, and leaves the peroxide. In order to heighten the green 
tint for which this compound is esteemed as a pigment, it should be re- 
peatedly washed with boiling water. 
858. There is a fine blue cupreous preparation, called Refiners’ Ver- 
iliter, principally made by silver refiners. It consists, according to 
Mr. R. Phillips, of 3 proportionals of oxide, 4 of carbonic acid, and 2 
ef water, {Quarterly Journal of Science and Arts, Vol. iv. p. 277.) 
There is a very inferior pigment, also called Verditer, which is a mix- 
ture of subsulphate of copper and chalk. 
According to Pelletier, a good verditer may be obtained as follows : 
add a sufficient quantity of lime to nitrate of copper to throw down the 
hydrated oxide ; it gives a greenish precipitate that is to be washed and 
nearly dried upon a strainer ; then incorporate with it from 8 to 10 
per cent, of fresh lime, which will give it a blue colour, and dry it care- 
fully. 
859. According to Mr. Chenevix, the alcaline carbonates dissolve a 
portion of the peroxide of copper, and form triple salts. ANALYSIS OP BRASS. 
84)0. Native Carbonate o f Copper is found of a green and blue colour. 
*Thc former, or Malachite, is found in various forms, but never regular- 
ly crystallized, the octoedral variety being a pseudo-crystal derived 
from the decomposition of the red oxide. This mineral occurs in the 
greatest beauty in the Uralian mountains of Siberia ; it is rarely found 
m Cornwall. It is of various shades of green, and often cut into small 
slabs, or used as beads and broach stones. The pulverulent variety has 
been termed chrysocolla and mountain green. 
The blue carbonate is found in great perfection at Chessy near Lyons; 
also in Bohemia, Saxony, 4’C. It occurs chrystallized in rhomboids and 
imperfect octoedra ; it also is found in small globular masses ; massive ; 
and earthy. The earthy variety is sometimes called copper azure or 
mountain blue. 
The Dioptase or Emefald Copper is a very rare mineral, hitherto found 
only in Siberia, associated with malachite. It consists, according to 
Lowitz, of oxide of copper, silica, and water. 
861. Borate of Copper.—Solution of borax, poured into sulphate of 
copper, produces a bulky pale green precipitate of borate of copper. 
862. Ferrocyanate of Copper is a brown compound, obtained by add- 
ing ferrocyanate of potassa to a dilute solution of sulphate or nitrate of 
copper. Mr. Hatchett has recommended this substance as a brown 
pigment. 
863. Many of the alloys of copper are important. With gold it forms 
a fine yellow ductile compound, used for coin and ornamental work. 
Sterling or standard gold consists of 11 gold -f* 1 copper. The speci- 
fic gravity of this alloy is 17.157. With silver it forms a white com- 
pound, used for plate and coin. Lead and copper require a high red 
heat for union ; the alloy is grey and brittle.—See Gold and Silver. 
Of the alloys of copper with the preceding metals the most impor- 
tant are brass and bell-metal. It forms white compounds with potas- 
sium and sodium ; a reddish alloy with manganese ; and a grey one 
with iron. 
864. Brass is an alloy of copper and zinc. The metals are usually 
united by mixing granulated copper with calamine (782) and charcoal: 
the mixture is exposed to heat sufficient to reduce the calamine and 
melt the alloy, which is then cast into plates. The relative proportions 
of the two metals vary in the different kinds of brass ; there is usually 
from 12 to 18 per cent, of zinc. Brass is very malleable and ductile 
when cold ; and its colour and little liability to rust recommend it in pre- 
ference to copper for many purposes of the arts. According to M. Sage* 
a very beautiful brass may be made by mixing 50 grains of oxide of cop- 
per, 100 of calamine, 400 of black flux, and 30 of charcoal pow'der ; 
tnelt these in a crucible till the blue flame is no longer seen round the 
cover ; and, when cold, a button of brass is found at the bottom, of a 
golden colour, and weighing one-sixth more than the pure copper ob- 
tained from the above quantity of oxide. 
865. The analysis of brass may be performed by solution in nitric 
acid; add considerable excess of solution of potassa and boil, which 
will dissolve the oxide of zinc and leave that of copper ; wash the lat- 
ter, and dry and heat it to redness : 125 parts indicate 100 of copper. 
The zinc in the filtered alcaline solution may be precipitated by car- 
bonate of soda, having previously added a small excess of muriatic 
acid ; wash this precipitate, dry it, and expose it to a red heat; it i$ 
then oxide of zinc, 123 parts of which indicate 100 of metal. LEAD. 
243 
86G. Tutenag is said to be an alloy of copper, zinc, and a little iron ; 
andTombac, Dutch gold, Similor, Prince Rupert's metal, and Pinchbeck, 
are alloys containing more copper than exists in brass, and consequent- 
ly made by fusing various proportions of copper with brass. Accord- 
ing to Wiegleb, Manheim gold consists of 3 parts of copper and 1 of 
zinc. A little tin is sometimes added, which, though it may improve 
the colour, impairs the malleability of the alloy. 
867. Speculum metal is an alloy of copper and tin, w ith a little arse- 
nic ; about 6 copper, 2 tin, 1 arsenic. On this subject the reader is 
referred to Mr. Edwards’s experiments.—Nicholson’s Journal, 
4to. iii. 
868. Bell metal and bronze are alloys of copper and tin ; they are 
harder and more fusible, but less malleable than copper ; the former 
consists of 3 parts of copper and 1 of tin ; the latter of from 8 to 12 of 
tin with 100 of copper. A little zinc is added to small shrill bells. 
868*. The analysis of alloys of tin and copper may be performed by 
digestion in nitric acid, which dissolves the copper and converts the 
tin into insoluble peroxide, which, when washed and dried, consists of 
100 tin + 27 oxygen. The cupreous solution may be decomposed by 
potassa, and the pure peroxide of copper indicates the quantity of that 
metal, as in the analysis of brass. (865.) 
869. Vessels of copper used for culinary purposes are usually coat- 
ed with tin, to prevent the food being contaminated with copper. 
Their interior surface is first cleaned, then rubbed over with sal-am 
moniac. The vessel is then heated, a little pitch spread over the sur- 
face, and a bit of tin rubbed over it, which instantly unites with and 
covers the copper. 
869*. The cupreous salts are nearly all soluble in water, and of a 
blue or green colour. Ammonia produces a compound of a very deep 
blue, when added in excess to these solutions ; hydrosulphuret of am- 
monia forms a black precipitate ; and a plate of iron plunged into a 
liquid salt of copper precipitates metallic copper. 
Ferrocyanate of potassa is also an excellent test of the presence of 
copper; it produces a brown cloud in solutions eontaining the pe- 
roxide. 
Section XIV. Lead. 
€70. The natural compounds of this metal are very numerous. 
The most important is the sulphuret, from which the pure metal is 
chiefly procured. Lead is also found combined with carbonic, sul- 
phuric, phosphoric, arsenic, molybdic, and chromic acids, and wfith 
oxygen and chlorine. To obtain lead perfectly pure, it may be dis- 
solved in nitric acid ; the solution evaporated to dryness ; the dry 
mass re-dissolved in water and crystallized; these crystals heated 
strongly with charcoal afford the meial quite pure. 
871. Lead appears to have been known in the earliest ages of the 
world. Its colour is bluish white. It melts at 600°, and by the unit- 
ed action of heat and air is readily converted into an oxide. Its spe- 
cific gravity is 11.4. At cogunon temperatures it undergoes little 
To <Shta.ii! jjprc 
lead. 
Characters of 
lead. 244 
CHLORIDE OF LEAD. 
change by mere exposure to air, but it is slowly corroded by the joint- 
agency of air and water. Exposed upon ignited charcoal to a current 
of oxygen gas, it burns with a blue flame, throwing off dense yellow 
fumes of oxide. The alchymistsgave this metalthe name of Saturn. 
872. Oxides of Lead.—There are three oxides of lead. The pro- 
toxide is the basis of the salts ; it may be obtained pure by heating the 
nitrate of lead to redness in a vessel with a small orifice, till the whole 
of the acid is expelled. It is insipid and insoluble in water, of a pale 
yellow colour, and, when fused, crystallizes on cooling in irregular 
scales. It is volatile at a bright red heat. It is very soluble in solu- 
tions of potassa and soda ; and when in fusion, it readily dissolves se- 
veral of the earthy bodies, and of the common metallic oxides ; hence 
the use of lead in cupellation. (885). If it be considered as a protox- 
ide, consisting of one proportional of lead and one of oxygen, then the 
number 104 (deduced from the mean of the best analyses) will repre- 
sent lead, and it will consist of 104 L. + 8 oxygen. This oxide is 
known in commerce under the name of massicot; or w'hen vitrified, 
as obtained by calcining lead upon a large scale, it is called litharge. 
When melted lead is exposed for a time to the air, it becomes in- 
crusted with a grey pellicle, which, on removal, is succeeded by an- 
other, and so on until the whole is converted into a greenish grey pow- 
der, consisting of a mixture of the protoxide with metallic lead. 
873. If the protoxide be exposed to heat and oxygen, it gradually 
acquires a bright red colour, and is known under the name of minium 
or deutoxide of lead. This oxide, when exposed to nitric acid, is re- 
solved into protoxide, which is dissolved, and into peroxide, which is 
an insoluble browm substance, consisting of 104 L. + 16 oxygen. 
When peroxide of lead is heated it gives out half its oxygen and be- 
comes yellowr protoxide. 
Minium affords, on analysis 104, L. + 12 oxygen, and may, therefore, 
be regarded as a definite compound of the protoxide and peroxide. 
The minium or red lead of commerce generally contains a proportion 
of protoxide and of sulphate, with traces of chloride of lead and silica. To 
succeed in obtaining it of a fine red tint, it requires to be manufactured 
in quantities, and with several precautions. The method employed in 
Derbyshire is described in Watson’s Chemical Essays, Vol. iii. p. 338. 
874. A substance supposed to be native minium, has been found In 
some of the Saxon and French lead mines, also in Yorkshire. 
875. Lead and Chlorine.—Chloride of Lead. When laminated lead is 
heated in chlorine, the gas is absorbed, and a chloride of lead results, 
composed of 104 L. + 36 C. (J. Davy, Phil. Trans., 1812.) The same 
substance is obtained by adding muriatic acid to nitrate of lead ; it is 
white and fusible, and on cooling forms a hornlike substance (plumbum 
corneum.) It volatilizes at a high temperature. It dissolves in 22 
parts of water at 60° ; is more soluble in boiling water, separating, as 
its solution cools, in small acicular crystals, unchanged by exposure to 
pir, and of a sweetish taste. It dissolves in dilute nitric acid. 
876. This substance is sometimes prepared by acting upon a solution 
of common salt by litharge ; solution of soda and chloride of lead are 
formed ; the insoluble residue when fused is known under the name 
pf patent yellow ; it appears to be a compound of oxide and of chloride 
of lead, for wrhen treated by nitric acid, it forms nitrate of lead, and a 
portion of chloride separates. NATIVE SULPHURET OP LEAD. 
245 
877. Native Chloride of Lead has been found in Derbyshire and in 
Bavaria, crystallized in quadrangular prisms of a greenish yelloAV 
colour. 
878. Chlorate of Lead is obtained by digesting the protoxide in chlo- 
ric acid ; it separates by sIoav evaporation, in white crystalline flakes 
of a very SAveet taste. When heated it gives out oxygen and becomes 
a chloride. 
879. Iodide of Lead, formed by heating leaf-lead with iodine, is a 
yellow insoluble compound. It is also formed by adding hydriodic acid 
or hydriodate of potassa to solution of nitrate of lead. It consists of 
Iodine 
125 
Lead 
104 
229 
880. An insoluble Iodate of Lead is thrown down on adding iodate oi' 
potassa to any of the soluble salts of lead. 
881. Nitrate of Lead is obtained by dissolving the metal, notin ex- 
cess, in dilute nitric acid, and evaporation. The salt crystallizes in 
letraedra and octoedra, which are white translucent, and of a styptic 
taste. It is soluble in 8 parts of water at 212°. It consists of 112 ox- 
ide of lead + 54 nitric acid, The alcalis throw down protoxide of lead 
from the solution of this salt. 
882. Subnitrate of Lead may be formed by boiling a mixture of equal 
weights of nitrate and protoxide of lead in Avater, filtering while hot, 
and setting it by to crystallize ; it forms pearly crystals, of a sweet as- 
tringent fiiste. (Chevreuil, Annales de Chimie, lxxxii.) It consists of 
two proportionals oxide = 224, -f- one proportional nitric acid — 54. 
883. Chevreuil and Berzelius have described three nitrites of lead, 
but their composition appears doubtful. (Ann. de Chim., lxxxiii. and 
lxxxviii.) A detailed account of them is given by Dr. Thomson.—Sys- 
tem, ii. 578. 
884. Sulphuret of Lead may be formed artificially by fusion. Its 
lustre and colour much resemble pure lead, but it is brittle : it consists 
of 104 lead -f- 16 sulphur. 
885. Native Sulphuret of Lead, or Galena, is the principal source of 
the vast commercial demands of the metal. It occurs massive and crys- 
tallized, chiefly in the older secondary rocks. Its.primitive form is the 
cube, of which there are several modifications, and among them the 
octoedron. It often contains traces of silver, and sometimes in such 
quantity as to render it rvorth separating, Avhich is effected by exposing 
the roasted sulphuret to the action of heat and air in shalloAV earthen 
dishes ; the lead becomes oxidized and converted into litharge, while 
the silver is left pure, iq consequence of its poiver of resisting the 
influence of heat and air. This process is called cupellation. The 
litharge is afterwards reduced by fusion with charcoal. 
The reduction of galena upon a large scale is a sufficiently simple 
process. The picked ore, after having been broken and Avashed, is 
roasted in a reverberatory fire, the temperature being such as to soften 
but not fuse it. During this operation it is raked till the fumes of sul- 
phur are dissipated, when it is brought into perfect fusion ; the lead 
sinks to the bottom, and is run out into oblong mouMs called pigs ; the 
scoriae are again melted, and furnish a portion of less pure metal. 
Litharge. 
Reduction of 
the ore. 246 
NATIVE PHOSPHATE OP LEAD. 
The mines of Great Britain afford an annual produce of about 48000 
tons of smelted lead, of which nearly the whole is obtained from the 
sulphuret. 
There is a peculiar variety of galena, called in Derbyshire slicken- 
sidcs; and which, when touched by the miner’s pick, often splits asun- 
der with a kind of explosion. 
886. Hyposulphite of Lead is precipitated in the form of a white 
powder, nearly insoluble in water, by adding solution of nitrate of lead 
to hyposulphite of potassa. It is composed, according to Herschel, of 
70.30 protoxide of lead + 29.70 hyposulphurous acid. These num- 
bers correspond to 1 proportional of oxide of lead = 112 + 2 pro- 
portionals of hyposulphurous acid — 48. 
887. Sulphite of Lead may be obtained by digesting yellow oxide of 
lead in sulphurous acid ; or by adding sulphurous acid or sulphite of 
potassa to nitrate of lead. It is white, insoluble, and tasteless, and con- 
sists of one proportional of each of its components ; namely, 32 sul- 
phurous acid +112 oxide of lead. When heated it loses sulphurous 
acid. 
888. Sulphate of Lead. When metallic lead is boiled in concentrated 
sulphuric acid, acid is evolved, and a white sulphate of lead 
is formed. It is so nearly insoluble, that it may be formed by adding 
dilute sulphuric acid, or an alcaline sulphate, to a solution of nitrate of 
lead. Dr. Thomson found, that after having been dried at a tempera- 
ture of 400°, it might be heated to redness in a platinum crucible with- 
out losing weight. Heated on charcoal by the blowpipe, it is decom- 
posed and reduced. It consists of one proportional of sulphuric acid 
= 40, and one proportional of oxide of lead =112; and its represen- 
tative number is therefore 152. Sulphate of lead is insoluble in alco- 
hol and in nitric acid : it is sparingly soluble in dilute sulphuric acid, 
and separates from it in small prismatic crystals. 
889. Native Sulphate of Lead is found in Anglesea, and in Scotland, 
crystallized in prisms and in octoedra. 
890. Hydrosidphuretted Oxide of Lead is of a deep brown colour, 
and is produced by adding sulphuretted hydrogen, or hydrosulphuret 
of ammonia, to any solution of lead ; hence the use of those com- 
pounds as tests of the presence of lead. 
891. Phosphuret of Lead may be formed by dropping phosphorus 
into melted lead. It is of the colour of lead, and soon tarnishes. 
892. Hypophosphite of Lead has not been examined. 
893. Phosphite of Lead was prepared by Berzelius by mixing mu- 
riate of lead with phosphite of ammonia. It is white, tasteless, and 
insoluble, and appears to consist of 1 proportional of oxide of lead = 
112+1 proportional of phosphorous acid = 20. 
894. Phosphate of Lead is formed by mixing solutions of nitrate of 
lead and phosphate of soda, or phosphoric acid. It is yellowish white ; 
insoluble in water ; soluble in fixed alcaline solutions, and in nitric 
acid. It is decomposed by sulphuric acid, and by hot muriatic acid. 
It fuses before the blowpipe, and crystallizes on cooling. It consists 
of 112 oxide of lead + 28 phosphoric acid = 140. 
895. Berzelius has described a subphosphate, a superphosphate, and a 
nitrophosphate of lead.—Annales de Chim. et Phys., ii. 
896. Native Phosphate of Lead has been found in the mines of 
Cumberland, Durham, Yorkshire, and of Wanlock Head, in Scotian^. 
SEckensides. ALLOYS OF LEAD. 
247 
Its colour is various shades of green, yellow, and brown. Its primitive 
fbrm is a rhomboid, but it usually occurs in six-sided prisms. It is 
semi-transparent and brittle. 
897. Carbonate of Lead.—When an alcaline carbonate is added to 
nitrate of lead, a white precipitate of carbonate of lead falls : it is 
tasteless, insoluble in water, but soluble in fixed alcaline solutions. It 
is employed as a white paint, under the name of white lead or ceruse, 
and is usually prepared by exposing sheet lead to the action of the va- 
pour of vinegar. The process is described in Aikin’s Dictionary, 
(Art. Lead.) It consists of 112 oxide of lead-f- 22 carbonic acid = 
134 carbonate of lead. 
898. Native Carbonate of Lead is one of the most beautiful of the 
metallic ores : it occurs crystallized and fibrous, the former transpa- 
rent, the latter generally opaque. It is soft and brittle, and occasion- 
ally tinged green with carbonate of copper, or grey by sulphuret of 
lead. The octoedron is its primitive form : it also occurs prismatic 
and tabular. It has been found in Cumberland and Durham, and the 
acicular variety of great beauty in Cornwall. 
899. Ferrocyanate of potassa produces a white precipitate when 
added to the soluble salts of lead. 
900. Borate of Lead is precipitated in the form of a white powder, 
when borate of soda is mixed with nitrate of lead. 
901. The soluble salts of lead have a sweetish austere taste, and are 
characterized by the white precipitate produced by ferrocyanate of po-i 
tassa, the deep brown by hydrosulphuret of ammonia, and the yellow' 
by liydriodate of potassa. 
The salts insoluble in water are dissolved by soda and potassa, and 
by nitric acid, when the metal is rendered manifest by sulphuretted 
hydrogen and other tests. Heated by the blowpipe upon charcoal 
they afford a button of metal. 
902. The Alloys of Lead with the preceding metals are not important, 
if we except that which it forms with tin. Common pewter consists of 
about 80 parts of tin and 20 of lead Equal parts of lead and tin consti- 
tute plumbers' solder; and what is termed pot-metal is an alloy of lead 
and copper. 
903. In analyzing these alloys, 100 grains in filings may be boiled to 
dryness in two ounces of nitric acid, water poured upon the residue, 
and filtered ; the peroxide of tin remains in the filter, and the nitrate of 
lead, which passes through in solution, may be converted into sulphate 
by adding sulphate of soda. 152 grains of sulphate of lead dried at a 
red heat, indicate 104 of metal; and 75 grains of washed peroxide of tin 
are equivalent to 59 grains of metallic tin. 
904. With potassium lead forms a brittle and very fusible alloy; 
with sodium the compound is equally brittle but less fusible. When 
exposed to air these alloys suffer decomposition in consequence of the 
oxidizement of the alcaline bases. The alloy of Lead and Manganese 
has not been examined. When lead is fused with iron two alloys are 
obtained ; that at the bottom of the crucible consisting of lead with a 
little iron ; while the superficial portion is iron with a little lead (Guv- 
ton Morveau, Am. dc Chip\.} lvii.) With zinc, lead forms a hard 
ductile alloy. 
Characters of 
the salts of 
lead. 248 
PEROXIDE OF ANTIMONY. 
Section XV. Antimony. 
905. This metal is found native in Sweden, in France, and in the 
Hartz ; but its principal ore is the sulphuret which is found massive 
and crystallized, and of which there are several varieties. The most 
common is the radiated, which is of a grey colour, brittle, and frequent- 
ly crystallized in four and six-sided prisms. This ore may be decom- 
posed, and the pure metal obtained from it, by the following process : 
Mix three parts of the powdered sulphuret with two of crude tartar, and 
throw the mixture by spoonfuls into a red-hot crucible ; then heat the 
mass to redness, and a button will be found at the bottom of the crucible, 
which is the metal as it commonly occurs in commerce, and is nearly 
pure. Reduce this button to fine powder, and dissolve it in nitro-mu- 
riatic acid ; pour this solution into water, which will occasion the pre- 
cipitation of a white powder, which is to be washed and mixed with 
twice its weight of tartar and exposed to a dull red heat in a crucible. 
The button now obtained is pure antimony. 
906. Antimony is of a silvery white colour, brittle, and crystalline 
in its ordinary texture. It fuses at about 800®, and is volatile at a high 
heat. Its specific gravity is 6.712. (Hatchett, Phil. Trans., 1803.) 
Placed upon ignited charcoal, under a current of oxygen gas, antimony 
burns with great brilliancy, throwing off its oxide in the form of a dense 
yellow smoke. 
907. Antimony and Oxygen.—These bodies form two well-defined 
compounds, the history of which is of great importance to the pharma- 
ceutical chemist. 
The Protoxide of Antimony is thus obtained : To 200 parts of sul- 
phuric acid add 50 parts of powdered metallic antimony. Boil the mix- 
ture to dryness, wash the dry mass, first in water, and then with a weak 
solution of carbonate of potassa ; a white powder remains, which when 
thoroughly washed with hot water, is Protoxide of Antimony. It may 
also be procured by dissolving antimony in muriatic acid, pouring the 
solution into water, and washing the white precipitate with weak solu- 
tion of potassa. 
908. This oxide may also be obtained by adding ammonia to solution 
of tartrate of antimony and potassa, heating the mixture and washing 
the precipitate in large quantities of boiling water. It is thus procur- 
ed in the form of a heavy white powder. This process is directed in 
the Pharmacopoeia. 
This protoxide exists in all the active antimonial preparations ; in 
emetic tartar, kermes, glass of antimony golden sulphuret, *$'C. It is 
fusible and volatile at a red heat: decomposed by sulphur and charcoal 
and when acted on by nitric acid, is converted into peroxide. If heat- 
ed with chlorate of potassa it deflagrates and also becomes peroxidiz- 
ed ; it is very soluble in muriatic acid, and readily forms emetic tartar 
when boiled in solution of tartrate of potassa. 
When metallic antimony in fusion is exposed to a bright red heat, it 
is converted into an oxide which appears to be the protoxide, and which 
condenses in long and delicate needles when sublimed. It was formely 
called argentine flowers of antimony. 
909. Peroxide of Antimony is procured by acting for a considerable 
Reduction of 
ore. OXIDE OF ANTIMONY. 
time upon the powdered metal, by excess of hot nitric acid, and expos- 
ing the product to a red heat. The diaphoretic antimony and Bezoar 
mineral of old Pharmacopoeia consisted of this oxide, which compared 
with the protoxide is nearly inert. 
910 Peroxide of antimony is also formed by exposing the metal or 
the protoxide mixed with five or six parts of nitre to a red heat, in a 
porcelain crucible, and washing the residue with hot water. It is yel- 
lowish white, but becomes buff-coloured when heated, and returns to 
its former tint on cooling. It neither fuses nor volatilizes at a bright 
red heat, but when exposed to the flame of a spirit-lamp urged by a 
blow-pipe, it passes off slowly in white fumes, being partially reduced 
by the hydrogen of the flame. 
911. Berzelius (Ann. de Chim., lxxxvi. 225), has described four ox- 
ides of antimony ; but it is probable that the first and the fourth are not 
distinct compounds : they are said to be constituted as follows : 
1 
Suboxide consisting of 100 antimony -{- 4.65 oxygen. 
2 
Oxidule 100 -j- 18.60 
3 
White oxide 100 -f* 27.90 
4 
Yellow oxide 100 -{- 37.20 
The two last oxides are called by Berzelius, stibious and stibic acids, 
or antimomous and antimonic acids 
The second and fourth are probably the oxides described in para- 
graphs 908 and 909, but their composition is by no means satisfactorily 
ascertained. 
912. Native Oxide of Antimony is occasionally found incrusting the 
native metal and the sulphuret. 
913. I have found by experiment that the oxygen in the protoxide 
(908) is to that in the peroxide (909) as 1 to 2 ; and if we consider 
these as the second and fourth oxide described by Berzelius, we obtain 
the number 40 as the representative of antimony. Dr. John Davy’s 
researches on the composition of the chlorides, (Phil. Trans., 1812,) 
give the number 42.5 as the representative of antimony ; and this near- 
ly agrees with my own experiments upon the composition of the pro- 
toxide, (obtained by pi’ecipitation from emetic tartar), which give 45, 
and which I shall therefore adopt. 
The protoxide of antimony will then consist of 
Antimony 48 Oxygen 8 =56*\ 
And the peroxide will be composed of 
Antimony 48 -f- Oxygen 16 = 64. 
914. The acid properties of peroxide of antimony were long since 
remarked by Thenard, (Ann. de Chim., xxxviii. and xli.) and the sub- 
ject has lately been investigated by Berzelius, who obtained it by ex- 
posing a mixture of one part of powdered antimony and six of nitre to 
* 45 is merely altered to 48 in order to be. proportional to 8 instead of 7.5 oxygen. Thej 
great discrepancy in the results of different Chemists makes it improper to offer any num < 
ber confidently. Brand gives his own the preference, although it does not agree with the 
42.5 of Dr. D. anv better than the 40 stated in his text. SULPHURET OF ANTIMONY. 
a red beat in a silver crucible for an hour. After washing oft' the so- 
luble matters by cold water, and digesting the white powder which re- 
mains in muriatic acid, washing and drying it at a red heat, it is pure 
antimonic acid, and consists of antimony 100, oxygen 37.2. 
915. Antimoniate of Ammonia is formed by digesting the acid in am- 
monia. On evaporation a superantimoniate of ammonia is obtained in 
the form of a white powder. 
916. Antimoniate of Potassa is contained in the white powder obtain- 
ed by igniting nitre and antimonj'. (919). It dissolves in hot water, 
and this solution produces precipitates of insoluble antimoniates in se- 
veral other metallic solutions. 
Our knowledge of the composition and properties of the oxides of 
antimony, and of most of their combinations, is still extremely imper- 
fect, and the whole subject requires further investigation before the 
anomalies that now present themselves can be cleared up. 
917. Antimony and Chlorine, combine in one proportion only to pro- 
duce the chloride of antimony. The powdered metal takes fire when 
thrown into the gas, and a compound, at first liquid, but afterwards con- 
creting, is formed. It may also be produced by the distillation of one 
part of powdered antimony with two and a half of bi-chloride of mer- 
cury ; or by dissolving the protoxide of antimony in muriatic acid, and 
evaporating to dryness. It consists of 48 A. -f- 36 C. The pure chlo- 
ride is a soft solid at common temperatures, but becomes liquid by a 
gentle heat, and crystallizes as it cools. It is the butter of antimony of 
old writers. It deliquesces by exposure to air ; and is a powerful caus- 
tic. When water is added to the chloride of antimony, a mutual de- 
composition ensues, and hydrated protoxide of antimony, formerly 
called Algarotti's powder, or mercurius vitce, and muriatic acid result. 
918. Chlorate of Antimony has not been examined. 
919. Iodide of Antimony is of a dark red colour; acted upon by 
water, it produces hydriodic acid and oxide of antimony. 
920. Iodate of Antimony is unknown. 
921. Nitric acid acts powerfully on metallic antimony, and if mixed 
with it in fine powder, will sometimes cause its inflammation. The 
metal becomes peroxidized, and scarcely an appretiable portion is re- 
tained in solution. As in some other cases of the vehement decompo- 
sition of nitric acid, ammonia is produced, (287) which may be render- 
ed sensible by pouring potassa on the white magma that results. 
Protoxide of antimony, digested in dilute nitric acid, produces a diffi- 
cultly soluble salt, which separates in white scaly crystals, and which 
appears to be a nitrate of antimony, but I have not particularly examin- 
ed it. 
922. Nitro-muriatic acid readily dissolves antimony, and forms an 
orange-coloured solution, which is decomposed by the addition of wa- 
ter. Iron or zinc immersed into this solution throws down a black pow- 
der, which, according to Thenard, is pyrophoric. 
923. Sulphuret of Antimony is easily formed by fusing the metal with 
sulphur. It consists of 48 A. + 16 S. Its colour is dark grey and 
metallic. Its specific gravity 4.36. It closely resembles the native 
sulphuret (905.) 
924. When the native sulphuret js exposed under a muffle to a dull 
red heat, it gradually loses sulphur and absorbs oxygen, being convert- 
ed into a grey powder, which consists of a mixture of protoxide of an- PHOSPHATE OF ANTIMONY. 
timony and sulphuret. If the heat be increased, this fuses into a trans- 
parent substance of a yellow or brown colour, formerly called glass of, 
antimony. Its composition is variable ; it generally contains about 851 
-percent, of protoxide and 15 of sulphuret. In that which is imported 
for pharmaceutical purposes, from Germany and Holland, there is usu- 
ally a portion of siliceous earth, and it is sometimes adulterated with 
oxide of lead. This fraud is easily detected by digesting the finely 
powdered glass in hot nitric acid, diluting the solution and filtering. 
The filtered liquor gives a white precipitate on the addition of sulphate 
of soda if lead were present. 
During the formation of glass of antimony, if the heat be raised too 
high the greater part of the protoxide sublimes in slender crystalline 
needles ; while another portion, if air be not excluded, passes into the 
state of peroxide, and undergoes no change at a very high temperature. 
Compounds of the protoxide with larger quantities of the sulphuret 
have been termed saffron of antimony or crocus metallorum, and liver of 
antimony. 
925. Neither the Hyposulphite nor the Sulphite of antimony are 
known. 
926. Sulphate of Antimony.—When sulphuric acid is boiled upon 
finely-powdered antimony, the metal is oxidized, and an acid sulphate 
and a subsulphate of antimony are the results. In both these salts the 
metal is in a state of protoxide. (907.) 
927. Hydrosulphuretted Oxide of Antimony.—This compound has 
long been known under the name of kermes mineral; it is commonly 
prepared as follows : Equal parts of sulphuret of antimony and common 
potash are fused together; the resulting mass is finely powdered and 
boiled in ten times its weight of water. The liquor is filtered while 
hot; and, during cooling, it deposits kermes. The mother liquor of 
kermes deposits a copious yellowish red precipitate upon the addition'of 
dilute sulphuric acid, which, when washed and dried, is known under 
the name of golden sulphur of antimony. In the London Pharmacopoeia 
it is called antimonii sulphuretum praicipitatum. 
In forming these compounds, the following changes seem to have 
taken place. The sulphuret of antimony and potassa act upon the wa- 
ter, a portion of which is decomposed ; hydrogen is transferred to the 
alcaline sulphuret, to form hydrosulphuret of potassa ; hydrogen and 
oxygen unite to the sulphuret of antimony, producing a hydrosulphuret- 
ted oxide of that metal (kermes), which remains dissolved in the hot al- 
caline hydrosulphuret, and of which one portion is precipitated as that 
solution cools. When dilute sulphuric acid is added, the hydrosulphu- 
ret of potassa is decomposed, sulphate of potassa is formed, and sulphur 
and sulphuretted hydrogen are liberated ; the sulphur falls in combina- 
tion with the kermes, producing the golden sulphur, or sulphuretted hy- 
drosulphuret. 
928. Phospliuret of Antimony is formed by heating together equal parts 
of oxide of antimony, phosphoric acid, and charcoal. It is white and 
brittle. 
929. Nothing is known respecting either the Hypophosphite or the 
Phosphite of antimony. 
930. Phosphate of Antimony has not been formed : in the London 
Pharmacopeia there is a preparation called pulvis antimonialis, formed 
by heating one part of sulphuret of antimony with twm of hartshorn 
Glass of anti- 
mony. shavings. The action of heat upon the sulphuret has already been des- 
cribed. (924.) Its effect upon the hartshorn shavings is to destroy the 
animal matter, leaving little else than phosphate of lime. So that the 
pulvis antimonialis consists essentially of protoxide of antimony, mixed 
with phosphate of lime. This preparation is usually considered analo- 
gous to, if not identical with, James's Powder, which, according to Dr. 
Pearson’s analysis (Phil. Trans., 1791), consists of 43 phosphate of 
lime, and 57 oxide of antimony. 
931. In examining Antimonial Powder from various sources, pre- 
pared according to the direction of the Pharmacopoeia, I have found it 
of very variable composition : sometimes it contains peroxide of anti- 
mony only ; sometimes there is a proportion of protoxide, and in some 
few cases the powder has consisted chiefly of bone-earth. These dif- 
ferences are referable to the mode of preparing it, but in almost every 
case, a very large proportion of the protoxide is lost during the pro- 
cess, and I have found it a matter of great difficulty so to conduct it as 
to obtain, upon the large scale, an uniform product. For medical use 
I should consider emetic tartar as the only certain and necessary pre- 
paration of antimony ; if, however, a compound of the nature of the 
Antimonial Powder be requisite, one of the best modes of preparing it 
would be to dissolve certain proportions of protoxide of antimony 
and phosphate of lime in muriatic acid, precipitate by ammonia, 
and edulcorate with a large quantity of water. Mr. Chenevix ad- 
vises for this purpose equal parts of the oxide and phosphate, but such 
proportion of antimony is too great: I have made an useful Antimonial 
Powder by dissolving 200 grains of bone-earth and 100 of protoxide of 
antimony in a measured ounce and a half of muriatic acid, and pouring 
the solution into a weak solution of ammonia ; the precipitate, when 
washed, dried, and reduced to a fine powder, weighed 280 grains. 
932. The following method furnishes, in tho dry way, a tolerably 
uniform Antimonial Powder: Burn two pounds of hartshorn to a cin- 
der, reduce it to powder, and heat it to a dull redness in an iron pot: 
then gradually stir into it one pound of powdered sulphuret of anti- 
mony, added in successive portions, and continue the same heat as long 
as fumes arise ; when these cease the mixture will have a dirty grey 
colour, and during the operation small crystals of protoxide of antimo- 
ny wall be seen to collect upon its surface when a portion is taken out in 
an iron spoon. In this grey state it should be put into a crucible and 
heated to intense redness; a phosphorescent light of a greenish tint is 
soon perceived, and when this ceases the crucible may be removed 
from the fire, and its contents when cold reduced to a fine powder, 
which should be perfectly white. 
933. Neither carbonate, hydrocyanate, nor borate of antimony are 
known to exist. 
934. The solutions of antimony afford orange-coloured precipitates 
\vith sulphuretted hydrogen, and those which are acid are precipitated 
when largely diluted with water. 
933. Antimony forms brittle alloys with the malleable metals. 
When gold was alloyed with TyVo its weight of antimony, the com- 
pound was perfectly brittle; and even the fumes of antimony in the 
vicinity of melted gold are sufficient to destroy its ductility. (Hatchett, 
Phil. Trans., 1803.) With potassium and sodium it forms white brittle 
compounds, destructible by the action of air and water. 
ANTIMONY. 
Mode of pre- 
paring antimo- 
fcial powder. BISMUTH. 
Its alloys with manganese and with zinc have not been examined. 
Alloyed with lead in the proportion of 1 to 16, and a small addition 
of copper, antimony forms the alloy used for printers'’ types. With; 
lead only, a white and rather brittle compound is formed, used for the 
plates upon which music is engraved. With iron it forms a hard whit- 
ish alloy formerly called marticd regulus, which may be obtained by 
fusing two parts of sulphuret of antimony with one of iron filings ; a 
scoria consisting chiefly of sulphuret of iron is formed, and the fused 
alloy beneath usually presents a stellated appearance in consequence 
of its crystallization. This star was much admired by the alchymists, 
who considered it a mysterious guide to transmutation. With tin an- 
timony constitutes a kind of pewter, a term however which has also 
been applied to some other alloys, especially that of lead and tin, 
(902.) The finest pewter consists of about 12 parts of tin and 1 of 
antimony, with a small addition of copper. A good white metal, used 
for teapots, is composed of 100 tin, 8 antimony, 2 bismuth, and 2 cop- 
per. 
936. The analysis of an alloy of tin, lead, copper, and antimony, 
may be thus performed : Introduce 100 grains into a matrass with a 
wide mouth, and pour upon it one ounce of water and two of nitric 
acid ; digest and evaporate to dryness. The dry mass will consist of 
the nitrates of lead and copper, which are soluble, and maybe taken 
up by two ounces of hot water, and of the peroxides of tin and anti- 
mony, which are insoluble, and remain upon the filter. 
To the solution of the nitrates add sulphate of soda, wThieh throws 
down sulphate of lead, and which is to be collected in a filter, washed, 
dried at a red heat, and weighed. (888.) The filtered liquor may be 
evaporated to about two ounces in bulk, and having rendered it slightly 
acid by dilute sulphuric acid, immerse in it a plate of iron, which will 
throw down metallic copper, to be purified if requisite (820), dried, 
and weighed. 
The separation of the peroxides of tin and antimony is attended with 
many difficulties : it may be imperfectly effected by solution in nitro- 
muriatic acid, and subsequent dilution with a large quantity of water, 
which throws down the antimonial oxide, not however pure, but with 
a portion of peroxide of tin : the latter, retaining a little peroxide of 
antimony, may be procured by evaporation and exposure of the resi- 
due to a dull red heat in a porcelain cup. 
Alloys. 
Section XVI. Bismuth. 
937. This metal is found native ; combined with oxygen ; and with 
arsenic and sulphur. 
Native Bismuth occurs crystallized in octoedra and cubes, and ge 
nerally contains arsenic and sometimes cobalt. It has been found in 
Cornwall, and in Germany, France, and Sweden. 
938. The metal may be obtained pure, by dissolving the bismuth of 
commerce in nitric acid ; water is added to the nitric solution, which 
separates oxide of bismuth. This oxide is easily reduced in the usual 
way. 254 
HYDRO SULPHURETTED OXIDE OF BISMUTH. 
Bismuth is a brittle white metal, with a slight tint of red : its specific 
gravity is 9.822. (Hatchett, Phil. Trans., 1803.) It fuses at 476°, 
and always crystallizes on cooling. 
939. When bismuth is exposed to heat and air it oxidizes, forming a 
fusible white oxide. If the heat be increased by directing a current of 
oxygen upon the metal, it burns with much brilliancy, and produces an 
abundant yellow smoke, which condenses in the form of a yellowish 
white sublimate. When in fusion this oxide acts upon other oxides 
much in the same way as oxide of lead. It consists of 72 bismuth -f- 
8 oxygen. It occurs, though very rarely, native: it has been found in 
Cornwall and Saxony. 
940. Chloride of Bismuth, is procured by heating the metal in the 
gas, or by evaporating the muriate to dryness and submitting the resi- 
due to distillation, when the chloride sublimes, and afterwards deliques- 
ces into what was called butter of bismuth. (J. Davy, Phil. Trans., 
1812.) It consists of 72 bismuth -j- 36 chlorine. 
941. Chlorate of Bismuth has not been examined. 
942. Iodide of Bismuth, obtained by heating iodine with the metal, 
is of an orange-colour, and insoluble in water. When hydriodic acid 
or hydriodate of potassa is added to nitrate of bismuth, a precipitate 
falls of a deep chocolate-brown colour, insoluble in water but soluble 
in liquid potassa. 
943. Iodate of Bismuth is thrown down upon adding iodate of potas- 
sa to nitrate of bismuth. 
944. Nitrate of Bismuth.—This salt crystallizes in small four-sided 
prisms, consisting of 80 oxide -f- 54 acid. It is made by dissolving the 
metal to saturation in two parts of nitric acid and one of water : the 
action is rapid, and nitric oxide is copiously evolved. Ammonia occa- 
sions a precipitate in nitrate of bismuth, which is re-dissolved by ex- 
cess of the alcali. Potassa and soda also throw down the oxide, which 
is but sparingly soluble in those alcalis. 
945. Nitrate of Bismuth is decomposed by water, and the oxide of 
bismuth is thrown down in the form of a fine white powder, called 
magistery of bismuth, pearl white, or blanc de fard. In this state it 
has been used in medicine as a tonic.—Quarterly Journal, viii. 295. 
946. If characters be written on paper with nitrate of bismuth they 
are invisible when dry, but become white and legible on immersion in 
water, thus forming a white sympathetic ink. The same characters are 
rendered brown or black by solution of sulphuretted hydrogen. 
947. Sulphuret of Bismuth is of a bluish colour and metallic lustre ; 
it consists of 72 B. -f- 16 sulphur. (J. Davy, Phil. Trans., 1812.) 
The compound analyzed by Vauquelin appears to have been a bi-sul- 
phuret.—Annales du Museum, Tom. xv. 
948. Native Sidphuret of Bismuth has been found in Cornwall, Bo- 
hemia, Saxony, and Sweden. It occurs massive and acicular, its lus- 
tre is metallic, and its colour bluish grey. It is a very rare mineral. 
949. Neither the Sulphite nor the Hyposulphite of Bismuth have 
been examined. 
950. Sulphate of Bismuth consists of 80 oxide -{- 40 acid ; it is a 
white compound, insoluble in, but decomposed by water, which con- 
verts it into a subsulphate and super sulphate. 
951. Hydrosulphuretted Oxide of Bismuth is of a deep brown ap- 
proaching to black. It is thrown down from nitrate of bismuth bv sul- 
phuretted hydrogen. COBALT AND OXYGEN. 
952. Phosphuret of Bismuth does not, according to Pelletier, exist; 
at least, it cannot be formed by the usual process. 
953. Neither the hypophosphite, phosphite, phosphate, carbonate, 
ferrocyanate, nor borate of bismuth hare been sufficiently examined. 
954. Bismuth forms alloys, some of which are remarkable for their 
fusibility. With gold, platinum, and silver, it forms brittle compounds. 
A compound of eight parts of bismuth, five of lead, and three of tin, 
liquefies at 212° ; it is called Sir. I. Newton’s fusible meted. The ad- 
dition of one part of quicksilver renders it yet more fusible. Bismuth 
enters into the composition of soft solders. These alloys are mostly 
white, brittle, and easily oxydated. 
Section XVII. Cobalt. 
955. The native combinations of cobalt are the oxide, and compounds 
©f the metal with iron, nickel, arsenic, and sulphur. It is also found 
combined with arsenic acid. In the white and grey cobalt ores, the 
metal is combined with iron, and with arsenic : Some of the varieties 
are crystallized in cubes, octoedrons and dodecaedrons. The red ore 
is an arseniate. The finest specimens are the produce of Saxony. 
956. To obtain pure cobalt, the cobalt of commerce, in fine powder,, 
may he calcined with four parts of nitre, and washed in hot water, by ] 
which arsenic is separated : then digest in dilute nitric acid, and im- 
merse a plate of iron, which will separate the copper ; filter and eva- 
porate to dryness; digest the dry mass in liquid ammonia and filter; 
expel the excess of ammonia from the filtered liquor by heat, taking 
care not to produce a precipitate, and then add solution of potassa, 
which throws down oxide of nickel; filter immediately, and boil, which 
will occasion the separation of oxide of cobalt, and which, ignited with 
charcoal, furnishes the pure metal. In this process the first calcination 
with nitre often requires two or three repetitions in order to get rid of 
the whole of the arsenic, which adheres to cobalt with much obstinacy. 
957. Cobalt is of a reddish grey colour, brittle, and difficultly fusi- 
ble. Its specific gravity is 7.7. It is magnetic. 
958. Cobalt and Oxygen unite in two proportions. The Protoxide is 
formed by adding potassa to the nitrate, and drying the precipitate ; it 
appears very dark blue or nearly black. By exposure to heat and air 
it absorbs an additional portion of oxygen, and is thus converted into 
black peroxide. The protoxide, when recently precipitated and moist, 
is blue; and, if left in contact of water, becomes a red hydrate. The 
composition of the protoxide of cobalt, deduced from the analysis of 
the chloride (960) is 32.5 cobalt + 8 oxygen = 40.5 ; or 100 cobalt 
-J- 24.7 oxygen*. 
This result is nearly the mean of those published by Proust, (An- 
nales de Chitnie, Vol. lx.) and ltothoff, (Annals of Phil. Vol. iii.) It 
To obtain 
pure cobalt. 
* Thomson in his last experiments (Ann. Ph. new series, p. 251) makes the atom of cobalt 
= 26. The number given above does not agree with a law which seems well established by 
all the foregoing substances, viz. that all numbers are even integers when hydrogen s= 1. SULPHATE OP COBALT. 
appeals from the experiments of the latter chemist, that the peroxide of 
cobalt contains 100 metal + 36.7 oxygen, which, in reference to the 
above deduction from the chloride, would lead us to consider it as con- 
taining one proportional of cobalt and one and a half of oxygen. All 
the salts of cobalt contain the protoxide. 
959. Cobalt burns when heated in chlorine ; and forms chloride of 
cobalt. When muriate of cobalt is evaporated to dryness, and the re; 
siduum heated to redness out of the contact of air, a substance of a blue 
colour and micaceous texture is obtained, which is a pure chloride of 
cobalt. It dissolves perfectly in water, forming a pink solution. 
960. As the chloride of cobalt is easily formed, and as it is a perfect- 
ly definite compound, it offers an unexceptionable substance, from 
which, by analysis, to deduce the equivalent number of the metal. 
For this purpose 32 grains of the pure chloride were dissolved in water, 
and decomposed by solution of nitrate of silver : the precipitate of 
chloride of silver dried at a dull red heat, weighed 68 grains, which is 
the equivalent of 16.73 grains of chlorine ; hence the 32 grains of 
chloride of cobalt are composed of 16.73chlorine -f- 15.27 cobalt; 
and 16.73 : 15.27 : : 36 : 32.8 = the equivalent of cobalt. The 
chloride of cobalt, therefore, may be considered as composed of 
1 proportional of cobalt . . 
1 chlorine . 
. = 32.8 
. = 36.0 
68.8 
961. Chlorate of Cobalt has not been examined. 
962. Muriate of Cobalt is a deliquescent salt, of a blue green colour ; 
it may be formed by digesting either oxide in muriatic acid ; if the pe- 
roxide be used, chlorine is evolved, and it passes to the state of pro- 
toxide. When a little diluted, this solution becomes pink ; the pale 
pink solution, when written with, is scarcely visible ; but if gently 
heated, the writing appears in brilliant green, which soon vanishes as 
the paper cools, in consequence of the salt absorbing the aerial mois- 
ture. This solution has been termed Hellot’s sympathetic ink. 
963. Iodide and Iodate of Cobalt remain unexamined. No precipi- 
tate is produced in muriate of cobalt either by hydriodic acid or hydri- 
odate of potassa. 
964. With nitric acid the oxide of cobalt furnishes a red deliques- 
cent nitrate of cobalt. 
965. Ammonia digested upon recently precipitated protoxide of co- 
balt slowly dissolves it, and forms a pale pink solution, which becomes 
deeper coloured by exposure to air, in consequence of the metal pas- 
sing to the state of peroxide. The ammoniacal solution of the perox- 
ide forms acicular crystals of a beautiful pink colour. 
966. Sulphuret of Cobalt is formed by heating the oxide with sul- 
phur. It is yellowish white. 
967. Neither the Sulphite nor the Hyposulphite of Cobalt have been 
examined. 
968. Sulphate of Cobalt forms red rhombic crystals, soluble in 24 
parts of water at 60°. It may be made by dissolving the newly preci- 
pitated protoxide in sulphuric acid diluted with its bulk of water. Ip CARBONATE OF COBALT. 
its crystallized state it consists of one proportional of oxide, one of 
acid, and seven of water ; or 
40.5 protoxide of cobalt 
40. sulphuric acid 
63. water 
143.5* 
When dried at a temperature of 500°, the crystals fall into a blue 
powder, which in a bright red heat fuses and gives out sulphuric acid 
leaving a black oxide. The blue powder is the anhydrous sulphate of 
cohalt, perfectly soluble in water, and forming a pink solution ; it is 
slightly deliquescent, and becomes lilac coloured by exposure to air. 
969. Fifty grains of dry sulphate of cobalt dissolved in water, fur- 
nished a precipitate with muriate of baryta, amounting, when dried at 
a red heat, to 75 grains of sulphate of baryta, which is the equivalent 
of 25.5 grains of sulphuric acid : this method of analysis, therefore, 
shows that sulphate of cobalt consists very nearly of equal weights of 
sulphuric acid and protoxide of cobalt, and may be considered as veri- 
fying the analysis of the chloride. (960.) 
970. Sulphate of cobalt forms triple compounds with potassa and 
with ammonia, which have not been examined. If it contain nickel, 
the crystals are of a greenish tinge, but pink when the cobalt is pure. 
971. Hydrosulphuretted Oxide of Cobalt is precipitated from the mu- 
riate by hydrosulphuret of ammonia, of a black colour. 
972. Phosphuret of Cobalt is a white brittle compound. 
973. Nothing is known respecting the Hypophosphite and Phosphite 
of Cobalt. 
974. Phosphate of Cobalt may be formed by double decomposition, 
as by adding phosphate of soda to muriate of cobalt; it is insoluble, of a 
lilac colour, and if mixed with eight parts of gelatinous alumina and 
heated, it produces a beautiful blue, which may sometimes be employ- 
ed by painters as a substitute for ultramarine. (Thenard, Tom. ii. p. 
419.) The theoretical composition of phosphate of cobalt is 34 oxide 
+ 28 acid = 62. (Thomson.) 
975. Carbonate of Cobalt is formed by decomposing the nitrate, mu- 
riate, or sulphate of cobalt by carbonate of potassa, or soda ; a reddish 
blue powder is precipitated. 
976. Ferrocyanate of potassa forms a grass green precipitate in so- 
lutions of cobalt. 
977. Solution of borax produces a pink precipitate in solution of mu- 
riate of cobalt, which is probably a borate of cobalt. 
978. The salts of cobalt all contain the protoxide ; they are decom- 
posed by ammonia, which, if added in excess,'re-dissolves the oxide : 
phosphoric, carbonic, arsenic, and oxalic acids, produce, by double de- 
composition, insoluble red or lilac precipitates in these solutions. 
979. The alloys of cobalt are unimportant. 
980. The chief use of cobalt is as a colouring material for porcelain, 
earthenware, and glass ; it is principally imported from Germany in the 
state of zajfre, and smalt or azure. 
(Thomson.) 
* If Thomson’s number 26 (which seems preferable) the oxide will be 26 + 8 ~ 34, anti, 
the compound = 34 protox : -f. 40 sulphuric acid 63 water e= 137. 8UPHURET OF URANIUM. 
Zajfrc is prepared by calcining the ores of cobalt, by which sulphur 
and arsenic are volatilized, and an impure oxide of cobalt remains, 
which is mixed with about twice its weight of finely-powdered flints. 
Smalt and azure blue are made by fusing zaffre with glass ; or by cal- 
cining a mixture of equal parts of roasted cobalt ore, common potash, 
and ground flints. In this way a blue glass is formed, which, while hot . 
is dropped into water, and afterwards reduced to a very fine powder. 
Section XVIII. Uranium. 
981. The native hydrated oxide of this metal has been termed ura- 
niie, or uranitic mica. Its crystalline form is the cube, and several 
modifications ; it often occurs in thin quadrangular plates. It exhibits 
various shades of yellow and green. It has been found in France ; and 
of great beauty near Callington, in Cornwall. 
982. The native sulphuret of uranium was formerly mistaken for an 
ore of zinc, and called pechblende, till Klaproth, in 1789, demonstrated 
it to contain uranium combined with sulphur. From this ore uranium 
may be obtained by the following process : Reduce it to powder, and 
expose it to heat in a muffle ; then digest in dilute nitro-muriatic acid, 
and precipitate by excess of ammonia, to retain oxide of copper ; col- 
lect and wash the precipitate, and dry it at a heat approaching red- 
ness. 
When exposed to a violent heat with a small quantity of charcoal pow- 
der, metallic uranium is obtained. 
Uranium is of a grey colour, brittle, and very difficult of fusion ; its 
specific gravity has not been ascertained with precision. Bucholz 
states it as = 9.0.—Gehlen’s Journal, iv. 
983. Very few experiments have hitherto been made upon this me- 
tal. The oxide precipitated from its nitric solution by alcalis is yellow, 
but by heating with charcoal it becomes black. 
984. Chloride, Muriate, and Chlorate of Uranium have not been ex- 
amined ; nor is any thing known of the Iodide or lodate of Uranium. 
985. Nitrate of Uranium, formed by digesting the peroxide in dilute 
nitric acid, and crystallizing, forms yellow prismatic crystals, easily so- 
luble deliquescent in a moist air, and containing, according to Bu- 
cholz, 
61 
oxide 
25 
acid 
14 
water 
100 
986. Subnitrate of Uranium, upon the authority of Bucholz, is form- 
ed by heating the nitrate, which renders a part insoluble in water, and 
separates in the form of a yellow powder. 
987. Sidphuret of Uranium exists native. Neither the Hyposulphite 
nor Sulphite of Uranium have been examined. MENACHANITE. 
259 
Sulphate of Uranium forms yellow prismatic crystals, decomposable 
by heat, and according to the analysis of Bucholz, consisting of 
70 
oxide 
18 
acid 
12 
water 
100 
988. According to the same authority, the peroxide of uranium con- 
sists of 80 metal -{- 20 oxygen = 100 ; so that if we consider it as con- 
taining one proportional of metal and two of oxygen, we obtain 64 as the 
representative number of uranium ; and as it is probable that the prot- 
oxide contains half the quantity of oxygen, the oxides would consist re- 
spectively of 64 uranium -f- 8 oxygen, and 64 uranium -f- 16 oxygen ; 
but these numbers are at variance with those derived from the analysis 
of the salts by the same author, and at all events are merely theoreti- 
cal. 
989. The salts of uranium have a yellow colour and an astringent 
metallic taste. Potassa forms in their solutions a yellow precipitate, 
and carbonate of potassa a white precipitate ; both these precipitates 
are insoluble in excess of pure alcali, but dissolve in the carbonate. 
Ferrocyanate of potassa produces a rich brown precipitate in solutions 
of uranium, which is very characteristic. 
Section XIX. Titanium. 
990. Titanium exists in the state of oxide in two minerals, in tita- 
wite and in menachanite. 
Titanite is a nearly pure oxide of titanium ; it is of a brown colour, 
and occurs embedded in the quartz and granite of primitive countries, 
and sometimes traverses rock crystals in tine hair-like filaments. In 
this country it occurs at Bedgellert, in Caernarvonshire; and near 
Killin, in Scotland. The finest specimens are those from the vicinity 
of Mont Blanc and St. Gothard. 
The mineral, known by the name of anatase, octoedrite, and oysanite, 
is nearly of the same nature as titanite. It is found in Bavaria, Nor- 
way, Switzerland, and in the valley of Oysans in France. 
Menachanite consists principally of oxides of titanium and iron ; it 
is found in the bed of a small stream at Menachan, in Cornwall. jVY- 
grine, iserine, rutilite, and sphene, are also ores of titanium. 
991. The metal may be obtained from titanite by fusion with potas- 
sa ; the fused mass, washed with water, leaves oxide of titanium, con- 
taining a little iron; it is to be dissolved in muriatic acid, and precipi- 
tated by oxalic acid. The oxalate affords the metal by intense ignition 
with charcoal : it is, however, scarcely possible to obtain it in any 
state of agglutination : in some trials made in the Royal Institution, 
nothing like globules of the metal could be procured, and the crucibles 
were always fused. 
992. From menachanite, white oxide of titanium may be obtained CERIUM. 
by fusing it with potassa, and adding muriatic acid to the alcalme solu- 
tion. 
993. Titanium is of the colour of copper. It is said to be suscep- 
tible of three degrees of oxidizement, the colours of the oxides being 
blue, red, and white. 
The blue is formed by exposing the metal to heat and air; the red 
is the native oxide ; and the white is that which is precipitated from the 
alcaline solution of titanite and menachanite by muriatic acid. Ac- 
cording to Vauquelin and Hecht, (.Journal des Mines, No. xv.) the 
white oxide contains 89 parts of red oxide and 11 of oxygen. 
994. The action of chlorine, of iodine, and of their acids, upon ti- 
tanium, have not been examined. The carbonate of titanium dissolves 
in muriatic, nitric, and sulphuric acids, and phosphoric acid occasions 
a white precipitate in these solutions. Neither the muriate, nitrate, 
nor sulphate, are crystallizable. The solution of the muriate is speedi- 
ly decomposed by exposure to light, and a white precipitate of oxide 
is formed in it. 
995. When the native oxides of titanium are fused with carbonate of 
potassa, at a temperature not too high, a white carbonate of titanium is 
formed. 
996. The solutions of titanium are colourless, and afford white pre- 
cipitates with the alcalis ; ferrocyanate of potassa gives a green preci- 
pitate, and infusion of galls a red one. Hydrosulphuret of ammonia 
occasions a greenish precipitate. 
Section XX. Cerium. 
997. This metal was obtained by Hisinger and Berzelius, from a 
mineral found at Bastnas in Sweden, to which they have given the name 
of ceritc. It is also contained in Allanite, a mineral from Greenland, 
first distinguished as a peculiar species by Mr. Thomas Allan, of Edin- 
burgh. It contains, according to Dr. Thomson’s analysis, about 40 
per cent, of oxide of cerium. 
The ore is calcined, pulverized, and digested in nitro-muriatic acid. 
To the filtered solution saturated with potassa, oxalic acid is added, 
which occasions a precipitate ; this, when dried and ignited, is oxide 
of cerium. 
This oxide is extremely difficult of reduction. Mr. Children suc- 
ceeded in fusing it by the aid of his powerful Voltaic apparatus, and 
when intensely heated it burned with a vivid flame, and was partly vo- 
latilized Vauquelin describes cerium as a hard white brittle metal. 
—Annales de Chimie, Vol. iv. 
998. Vauquelin and Hisinger have described two oxides of ceri- 
um. The protoxide is white, and consists of cerium 100 —oxygen 
17.41. The peroxide is brown, and contains cerium 100 -f- oxygen 
26.11. If we regard the first oxide as containing 1 proportional of 
metal + 2 of oxygen, and the second, 1 -{— 3, then the number repre- 
senting cerium will be 91.9 and the oxides will consist respectively 
of 91.9 cerium +16 oxygen, and 91.9 cerium + 24 oxygen. CHLORIDE of tellurium. 
999. Muriatic and sulphuric acids dissolve the red peroxide of ce- 
rium : the solutions afford yellow crystals. The, muriate is deliques- 
cent ; the sulphate difficultly soluble. The Sulphate of the protoxide 
forms white crystals of a sweet taste. Nitric acid forms with the pro- 
toxide a deliquescent compound, of a sweet taste. The carbonate is 
precipitated from these solutions in the form of a white powder. 
1000. The salts of cerium are either white or yellow, as they con- 
tain either the protoxide or peroxide. Their neutral solutions taste 
sweet. Ferrocyanate of potassa, and oxalate of ammonia, produce 
white precipitates soluble in nitric and muriatic acids. Neither sulphu- 
retted hydrogen, nor gallic acid, occasion any precipitate. 
Section XXI. Tellurium. 
1001. The ores of tellurium are, 1. Native, in which the metal is 
combined with iron and a little gold. 2. Graphic ore, which consists of 
tellurium, gold, and silver. 3. Yellow ore, a compound of tellurium, 
gold, lead, and silver ; and 4. Black ore, consisting of the same metals 
with copper and sulphur. 
These ores have only been found in the Transylvanian mines, and in 
Siberia. 
The metal is extracted from them by precipitating their diluted ni- 
tro-muriatic solution by potassa, which is added in excess ; the clear 
liquor is poured off and saturated with muriatic acid, which affords a 
precipitate of oxide of tellurium. This heated in a glass retort with 
charcoal, furnishes the metal. Tellurium is of a bright grey colour, 
brittle, easily fusible, and very volatile. Its specific gravity is 6.1. 
1002. Oxide of Tellurium.—Exposed to heat and air, tellurium readi- 
ly burns, exhaling a peculiar odour, and forming a yellowish white ox- 
ide, consisting according to Klaproth, (Beitriige, Vol. iii.) of 
Tellurium 100 
Oxygen 20.5 
lienee the number 39 may be adopted as the representative of the 
metal; and if the above be considered a protoxide, it will contain 
1 proportional of tellurium = 
39 
1 of oxygen — 
8 
Oxide of tellurium — 
47 
1003. Chloride of Tellurium is a white fusible compound, formed by 
heating the metal in chlorine. According to Davy, (Elements, p. 410.) 
it consists of 2 tellurium -j- 1.85 chlorine, which would give 1 propor- 
tional of each of its components, or 
Tellurium 
39 
Chlorine 
3G 
Chloride of tellurium 
75 SELENIUM. 
The Chlorate of Tellurium is not knowm. 
1004. Iodine readily combines with tellurium, forming a deep brown 
iodide, which dissolves in wrater, forming the hydriodute of tellurium. 
The lodate of Tellurium has not been examined. 
1005. The salts of tellurium are decomposed by the alcalis, and the 
precipitate is re-dissolved when they are added in excess. Hydrosul- 
phuret of ammonia forms a brown precipitate ; ferrocyanate of potassa 
occasions no change. Zinc or iron, immersed into the solutions, cause 
the separation of metallic tellurium. 
1000. Tellurium combines with hydrogen, producing telluretlcd hy- 
drogengas. The soluble salts of tellurium furnish white precipitates 
when neutralized by alcalis, which are soluble in excess either of the 
solvent or precipitant 
1007. The oxide of tellurium is readily soluble in muriatic, nitric, 
and sulphuric acids. The muriate affords a precipitate on the addi- 
tion of water.—Berzelius, Nicholson’s Journal, xxxvi. 
1008. The oxide of tellurium combines with many of the metallic 
oxides, acting the part of an acid, and producing a class of compounds 
which have been called tellurates. 
1009. Tellurate of Potassa may be formed by heating oxide of tel- 
lurium with nitre, and dissolving the residuum in boiling water, which, 
on cooling, deposits an imperfectly crystallized white powder, difficultly 
soluble in water. 
1010. Solution of telluriate of potassa, added to solutions of lime, 
baryta, strontia, copper, and lead, forms insoluble tellurates of the ox- 
ides of those metals. 
Section XXII. Selenium. 
1011. This body is placed, rather from analogy Ilian experiment, 
among the metals. It was discovered by Berzelius in the sulphur of 
Fahlun in Sweden, and was first suspected to be tellurium. Its colour 
is grey ; its lustre bright metallic. It fuses at a few degrees above the 
boiling point of water, and wrhen slowly cooled, assumes a granular 
fracture. It boils and evaporates in close vessels at a temperature a 
little below redness. Heated before the blow-pipe it volatilizes with 
a very powerful and peculiar smell, somewhat like that of horse-ra- 
dish. 
Selenium unites with the metals. With potassium it combines with 
great energy, producing a greyish compound, with metallic lustre, and 
which, when thrown into water, evolves selenuretted hydrogen gas, which 
is highly irritating to the nostrils. It combines both in the dry and 
humid wray with the fixed alcalis, and forms red compounds. Heated 
to dryness w ith nitric acid it forms a volatile and crystallizable com- 
pound, called selenic acid, which unites to some of the metallic oxides, 
producing a distinct class of seleniates.—Annales de Chimie et Physique, 
Tom. vii.; Thomson’s Annals, Vol. xi. and xii. ARSENIOUS ACIB. 
263 
Section XXIII. Arsenic. 
1012. This metal may be obtained from the white arsenic of com- 
merce, by mixing it with half its weight of black flux*, and introducing 
the mixture into a Florence flask, placed in a sand bath, gradually raised 
to a red heat: a brilliant metallic sublimate of pure arsenic collects in' 
the upper part of the flask. The volatility of white arsenic prevents 
its easy reduction by charcoal alone ; but the potassa in the flux enables 
it to acquire a temperature sufficient for its perfect reduction. 
1013. Arsenic is of a steel blue colour, quite brittle, and of a spe-( 
cific gravity = 8.3. It readily fuses, and in close vessels may he dis- 
tilled at a temperature of 360°, which is lower than its fusing point. 
Its vapour has a very strong smell, resembling that of garlic. Heated 
in the air it easily takes fire, burns with a blue flame, and produces co- 
pious white fumes of oxide. Exposed to a moist air it gradually be- 
comes incrusted with a grey powder, which is an imperfect oxide. 
This metal and all its'eompounds are virulent poisons. 
1014. Native arsenic has been found in Saxony, Hanover, France, 
Bohemia, and Cornwall. It usually occurs in rounded masses, or no- 
dules, of a foliated lamellar texture, in the veins of primitive rocks, and 
is often associated with silver, cobalt, lead, and nickel ores. 
1015. Arsenic and Oxygen.—There are two definite compounds of 
arsenic and oxygen, which are both capable of forming combinations 
with other metallic oxides. They are sour and soluble in water, and 
have thence been properly termed arsenious and arsenic acids. 
The arsenious acid, or, as it is commonly called, white arsenic, or 
white oxide of arsenic, is the best known, and most commonly occur- 
ring compound of this metal; and as cases of poisoning by it are fre- 
quent, every person should be well acquainted with its characteristic 
properties. 
1016. Arsenious acid may easily be procured by the combustion of 
the metal; but as it is formed during certain metallurgic processes, 
£hat mode is rarely resorted to. It is abundantly prepared at Joa- 
chimsthal in Bohemia, from arsenical cobalt ores, which are roasted in 
reverberatory furnaces, and the vapours condensed in a long chimney, 
the contents of which, submitted to a second sublimation, afford the 
white arsenic of commerce. 
1017. Arsenious acid is white, semi-transparent, brittle, and of a 
vitreous fracture. Its specific gravity is 3.7. Its taste is acrid, accom- 
panied by a very nauseous sweetness, and it is virulently poisonous, 
producing inflammation and gangrene of the stomach and intestines ; it 
also proves fatal when applied to a wound ; and as the local injury is 
in neither case sufficient to cause death, it is probable that an induced 
affection of the nervous system and of the heart is the cause of the mis- 
chief. (Brodie’s Observations and Experiments on the Action of Poi- 
Mode of ob- 
taining. 
Characters, 
* This is an extremely useful compound For effecting the reduction of many of the metallic 
•xides. It consists of charcoal and subcarbonate of potassa, and is best prepared by defla- jjjacK fl,,, 
grating in a crucible a mixture of one part of nitre and two of powdered tartar. The mixture 
remains in fusion at a red heat, and thus suffers the small globules of reduced metal to coa- 
lesce into a button. sons.—Phil, Trans., 1812 ) To get rid of the poison by producing co- 
pious vomiting and purging, and to pursue the usual means for subdu- 
ing and preventing inflammation, are the principal points of treatment 
to be adopted in cases where this poison has been taken.—Orfila. 
Traite des Poisons, Tom. i. p. 123. 
1018. By a slow sublimation arsenious acid forms tetraedral crystals : 
it is volatile at 380°, and has no smell when perfectly free from metal- 
lic arsenic. (Dr. Paris, Quarterly Journal of Science and Arts, Vol. 
vi.) According to Klaproth, 1000 parts of water at 60° dissolve 2.5»of 
■white arsenic ; and 1000 parts of water at 212°, dissolve rather more 
than 77 parts, and about 30 parts are retained in permanent solution. 
The solutions taste acrid and nauseous, and redden vegetable blues. 
80 parts of alcohol at 60°, dissolve one part of this acid. Its aqueous 
solution furnishes tetraedral crystals by slow evaporation. 
1019. The composition of the arsenious acid, as estimated by 
Proust, Thenard, and Thomson (Thomson’s System, Vol. i. p. 295.) 
furnishes the following mean : 
ARSENITE OF POTASSA. 
Arsenic. 
©xjrgen. 
Arsenious Acid. 
100 -f 
34 
= 134. 
If we consider this acid as a compound of one proportional of ar- 
senic and two of oxygen, we obtain the number 47.06 as the repre • 
sentative of arsenic ; for 
34 : 100 : : 16 : 47.06*. 
Without material error, therefore, we may adopt 47 as the repre- 
sentative of this metal, and the arsenious acid will then consist of 47 
arsenic -4- 16 oxygen = 63. 
1020. Native White Arsenic occurs in prismatic crystals, and in a 
pulverulent form : it is found in Saxony and Hungary. 
1021. The arsenious acid forms a distinct class of salts, called ar- 
senites, which have been but little examined. 
The arsenites of ammonia, potassa, and soda, are easily soluble and 
uncrystallizable : they are formed by boiling the acid in the alcaline 
solutions. Those of lime, baryta, strontia, and magnesia, are difficult- 
ly soluble, and formed in the same way. Arsenite of potassa is the ac- 
tive ingredient in the liquor arsenicalis of the Pharmacopoeia, and in 
Fowler's mineral solution or tasteless ague drop. 
Arsenite of ammonia produces a yellow precipitate in nitrate of sil- 
ver, easily soluble in excess of ammonia. 
Arsenite of potassa produces a white precipitate in the white salts of 
manganese ; a dingy green precipitate in the solutions of iron ; a white 
precipitate in solutions of zinc and tin. Mixed with a solution of sul- 
phate of copper, a precipitate of a fine apple-green colour falls, called 
from its discoverer, Scheele's green, and is useful as a pigment. In the 
solutions of lead, antimony, and bismuth, it forms white precipitates : 
added to nitrate of cobalt it forms a pink precipitate ; and bright yel- 
* Thomson gives the composition of arsenic acid 4.75 arsenic -{- 3 atoms oxygen, (hence 
when the atom of hydrogen = 1), the atom of arsenic will be 38, and the arsenic acid 38 -f* 
24=62, so also arseniceous acid will be 38+16=54, this last number seems preferable to 63, 
but no substitution has appeared proper as the numbers in the text are deduced from particu- 
lar experiments. AltSENIATE or SODA. 
low, with nitrate of uranium. With nitrate of silver it forms a white 
precipitate, soon becoming yellow, and very soluble in ammonia. All 
these precipitates are probably arsenites of the respective metals, and, 
heated by a blow-pipe on charcoal, they exhale the smell of arsenic. 
Native Arsenite of Lead is found in France, in Spain, and in Siberia. 
1022. Arsenic Acid is obtained by distilling a mixture of 4 parts of 
muriatic and 24 of nitric acid off 8 parts of arsenious acid, gradually 
raising the bottom of the retort to a red heat at the end of the opera- 
tion. It may also be procured by distilling nitric acid off powdered 
metallic arsenic. 
1023. Arsenic acid is a white substance, of a sour taste ; it is deli- 
quescent and uncrystallizable. Its specific gravity is 3.4. It requires 
for solution 6 parts of cold and 2 of boiling water ; its solution reddens 
vegetable blues, and tastes acrid and metallic. 
1024. It appears, from the experiments of Proust and Thomson, 
that the oxygen in the arsenic acid is, to that in the arsenious acid, as 3 
to 2 ; hence we may regard it as a compound of 1 proportional of ar- 
senic = 47, and 3 proportionals of oxygen = 24, and its representa- 
tive number will be 71. 
1025. The Arseniates are produced by the union of this acid with 
the metallic oxides ; and many which are insoluble may be formed by 
adding arseniate of potassa to their respective solutions. 
1026. Arseniate of Ammonia is formed by saturating arsenic acid 
with ammonia ; rhomboidal prisms are obtained on evaporation, which, 
when gently heated, effloresce and evolve ammonia : at a higher tem- 
perature water is formed, oxide of arsenic sublimes, and nitrogen is 
evolved, a circumstance first observed by Scheele. 
1027. Arseniate of Potassa is deliquescent and uncrystallizable. 
1028. Binarseniate of Potassa may either be formed by adding excess 
of arsenic acid to potassa and evaporation ; or by heating to redness, in 
a Florence flask, a mixture of equal parts of nitre and white arsenic ; 
during the latter operation much nitrous gas is evolved, and on dissolv- 
ing the residue in water, filtering, and evaporating, quadrangular crys- 
tals of binarseniate of potassa are obtained. Macquer was the first 
who thus procured this compound, hence it was termed MacquePs neu- 
tral arsenical salt. It is not easily decomposed by heat alone, and 
may be fused and kept red hot without undergoing other change than 
losing a little acid, but when mixed with about an eighth of charcoal 
powder and distilled, metallic arsenic rises, and carbonate of potassa, 
mixed with part of the charcoal, remains in the body of the retort. 
This salt is used in pharmacy for the cure of agues : it consists of 
1 proportional of potassa 
. . = 48 
2 arsenic acid . . 
. . = 142 
190 
1029. Arseniate of Soda is formed by saturating a solution of carbo- 
nate of soda with arsenic acid ; on evaporation crystals are obtained, 
which appear to consist of 
1 proportional of soda 
1 arsenic acid . . 
. . — 32 
. . = 71 
10,3 ARSENIATE OF LEAD. 
1030. Arseniate of Lime is deposited when arsenic acid is dropped 
into lime-water, or when arseniate of potassa is added to nitrate of 
lime ; it is difficultly soluble in water, and consists, according to Lau- 
gier (Annales de Chimie, lxxxv. 58.) of 
Arsenic acid 67 
Lime 33 
numbers which do not exactly correspond with 1 proportional of acid 
+ 1 of base. 
1031. Arseniate of Baryta may be formed by mixing arseniate of 
potassa with nitrate of baryta ; when the acid is not in excess it is inso- 
luble in water. It may be considered as a compound of 1 proportional 
of acid = 71 + 1 of baryta = 78. 
1032. Arseniate of Strontia is formed as the last, and is insoluble. 
1033. Arseniate of Magnesia is soluble, deliquescent, and uncrystal- 
lizable. 
1034. Arseniate of Manganese is precipitated in the form of a white 
powder, when arseniate of potassa is added to muriate of manganese. 
1035. Arseniate of Iron.—Arseniate of ammonia, added to the solu- 
tions of protosulphate and persulphate of iron, occasions greenish pre- 
cipitates of protarseniate and perarseniate of iron both of which have 
been examined by Mr. Chenevix.—Phil. Trans., 1801, pp. 220, 225. 
1036. Arseniate of Zinc is precipitated in the form of a white insolu- 
ble powder when arsenic acid, or an alcaline arseniate is added to sul- 
phate of zinc. 
1037. Arseniate of Tin is a white insoluble powder, precipitated by 
adding arseniate of potassa to muriate of tin. 
1038. Arseniate cf Copper is formed by adding an alcaline arseniate 
to nitrate of copper; it is a blue insoluble powder. The arseniates 
of copper have been submitted to an elaborate investigation by Mr. 
Chenevix (Phil. Trans., 1801.); he has described five varieties, as 
shown in the following table.—Thomson’s System, ii. 616. 
Acid. 
Oxide. 
Water. 
Variety ls£ 
1. . 
. . . 3.70 . . 
. . 2.60 
2 d 
1. . 
. . . 2.76 . . 
. . 1. 
3d 
1. . 
. . . 1.72 . . 
. . 0.70 
4th 
1. . 
. . . 1.80 . . 
. . 0.53 
5th 
1. . 
. . . 0.88 . . 
. . 0.60 
Dr. Thomson considers these varieties as reducible to four sub-spe- 
cies, as follow : 1 si:. A subarseniate, composed of 1 atom acid + 3 
atoms peroxide. 2d. A subarseniate, composed of 1 atom acid -f- 2 
atoms peroxide. 3d. and 4th. A neutral arseniate, composed of 1 
atom acid + 1 atom peroxide. 5th. A binarseniate, composed of 2 
atoms acid + 1 atom peroxide. 
1039. Arseniate of Lead. It may be formed by pouring arsenic acid 
into any of the soluble salts of lead, when it falls in the form of a white 
powder, insoluble in water, but soluble in dilute nitric acid ; a circum- 
stance which enables us in analyses to separate it from sulphate of lead, 
which is insoluble (888.) This compound is fusible without decompo- 
sition ; but if it be heated with charcoal, both the lead and arsenic 
are reduced, and the latter evaporates. This compound consists, ac- 
cording to theory,of Arsenic acid . . . , 
38.5 
Oxide of lead . . . 
61.5 
100. 
Thenard’s analysis (Annales de Chimie, i.) gives its component 
parts 
Acid 
35.7 
Oxide 
G4.3 
100.0 
1040. Arseniate of Antimony.—Nothing is known respecting the 
combinations of arsenic acid with either of the oxides of antimony. 
1041. Arseniate of Bismuth falls as an insoluble white powder on add- 
ing arsenic acid to nitrate of bismuth. 
1042. Arseniate of Cobalt is precipitated of a red colour by the ad- 
dition of an alcaline arseniate to a soluble salt of cobalt. 
1043. Arseniate of Uranium is thrown down of a straw colour when 
arseniate of potassa is added to nitrate of uranium. 
1044. Several of the metallic arseniates are found native; of these 
the most important are, 1. The arseniate of iron, which occurs in 
Cornwall, usually in cubic crystals of various shades of green. 2. Ar- 
seniate of copper, of which there are two principal varieties, the green 
and blue. The green is found in flattened octoedra, in hexaedral tables, 
and in prisms with dihedral summits. Sometimes it is massive, or fi- 
brous, and radiated. The blue variety is tetraedral, octoedral, and 
rhombic. These beautiful minerals are almost peculiar to Cornwall. 
3. Arseniate of lead occurs in small hexaedral crystals, of a yellow, 
green, or brown colour, transparent, and of a resinous lustre. It has 
been found in Cornwall, France, and Spain. 4. Arseniate of Cobalt, 
or peachblossom cobalt ore, is a rare mineral found in Saxony and Corn - 
wall. 
1045. Arsenic and Chlorine.—Chloride of arsenic is formed by throw- 
ing finely-powdered arsenic into chlorine 5 the metal burns and forms 
a whitish deliquescent and volatile compound ; it may also be obtained 
by distilling 6 parts of corrosive sublimate with 1 of powdered arsenic ; 
the chloride passes into the receiver in the form of an unctuous fluid, 
formerly called butler of arsenic. Mixed with water, the chloride of 
arsenic is decomposed, and white oxide or arsenious acid is deposited, 
muriatic acid being at the same time produced. Hence it may be in- 
ferred, that the chlorine is to the arsenic in the same proportion as the 
oxygen, and, consequently, that it consists of 1 proportional of arsenic 
+ 2 proportionals of chlorine, which, from Dr. Davy’s experiments, ap- 
pears to be the case. Chloride of arsenic therefore, is composed of 
47 arsenic + 72 chlorine =119 chloride of arsenic. 
1046. Chlorate of Arsenic has not been examined. 
1047. Iodide of Arsenic, obtained by heating the metal with excess 
of iodine, is of a deep red colour, and volatile. When acted upon by 
water, it produces hydriodic and arsenic acids, whence it appears pro- 
bable that it contains 1 proportional of arsenic and 3 of iodine. 
1048. The action of iodic acid on arsenic has not been examined- ARSENIC AND SULPHUR. 
1049. Arsenic and Hydrogen.—Arsenuretted Hydrogen Gas.—When 
arsenic is presented to nascent hydrogen, a portion of the metal com 
bines with the gas. The compound is best obtained by adding a por- 
tion of metallic arsenic, or of white arsenic, to the mixture of zinc 
filings and dilute sulphuric acid, usually employed for the production 
of hydrogen. (227). The gas may be collected over water, by which 
it is not sensibly absorbed. 
1050. The specific gravity of this gas is liable to vary according to 
the mode by which it is procured. I have always found it heaviest 
when obtained from a mixture of 4 parts of zinc, 1 of arsenic, and 3 
of sulphuric acid, diluted with 4 or 5 of water. After standing a day 
over water, it deposits a small quantity of brown matter, which appears 
to be a hydruret of arsenic, and then has a specific gravity of from 12 
to 14, hydrogen being = 1. This is considerably heavier than the 
usual estimation. If the gas were composed of 1 proportional of arse- 
nic and two of hydrogen, without condensation, 100 cubical inches should 
weigh 51.75 grains, and its speciiic gravity to hydrogen wmuld be 20.7. 
But Gay-Lussac and Thenard, (Recherckes Physico-Chimiques, Tom. i. 
p. 230.) have shown by decomposing it by tin, that 100 parts expand 
to 140, which would still increase its speciiic gravity, it being probable 
that 3 volumes of hydrogen are condensed into 2. It is probable, there- 
fore, that the gas, hitherto described under the name of arsenuretted 
hydrogen, is a mixture of the real compound with hydrogen. 
1051. The gas obtained by the above-described process is expanded 
in volume and deposits arsenic at high temperatures : exposure to in- 
tense cold is said to occasion its liquefaction. It smells strongly allia- 
ceous ; it extinguishes a taper, and burns with a pale blue flame, de- 
positing arsenic and its oxide. If detonated with about 4 volumes of 
oxygen, arsenious acid and water are formed. According to Stromeyer, 
(Nicholson’s Journal, Vol. xix.) it requires for its perfect combustion 
0.72 parts of its bulk of oxygen ; but this is probably not sufficient to 
burn the arsenic. 
1052. If bubbles of chlorine be passed up into ajar of arsenuretted 
hydrogen, standing over warm water, flame and explosion are often 
produced, muriatic acid is formed, and a brown hydruret is deposited ; 
but if the gas be passed in the same way by successive bubbles into 
chlorine, no inflammation results, absorption takes place, and muriatic 
acid and chloride of arsenic are formed. If the chlorine be not very 
pure, and when the gases are cold, inflammation seldom follows their 
mixture. 
1053. Chlorine, added to a mixture of sulphuretted with arsenuret- 
ted hydrogen, causes a deposit of red sulphuret of arsenic. 
1054. Nitric acid suddenly decomposes arsenuretted hydrogen ; wa- 
ter, oxide of arsenic, nitrous acid, and nitric oxide are the results. 
1055. Arsenic and Sulphur.—By slowly fusing a mixture of metallic 
arsenic and sulphur, or by heating white arsenic with sulphur, a red 
sulphuret of arsenic is obtained. It is crystallizable, and of a vitreous 
fracture : its specific gravity is 3.4. It is usually known under the 
name of realgar, and occurs native in Germany and Switzerland, in 
veins of primitive rocks and among volcanic matter. Its primitive form 
is an acute octoedron. 
10&6. If white arsenic be dissolved in muriatic acid, and precipitat- 
ed by hydrosulphuret of ammonia, a fine yellow sulphuret of arsenic PHOSPHATE OF ARSENIC. 
falls, which it appears only differs in form from realgar : it is usually 
called orpiment. According to Laugier, (Annales de Cfiimie, lxxxv.) 
these sulphurets are composed of about 58 arsenic and 42 sulphur, 
which differs little from 1 proportional and 2, or 
47 arsenic 32 sulphur = 79 sulphuret of arsenic. 
1057. Native Orpiment is of a bright lemon or golden colour. It is 
generally massive and lamellar. It occurs both in primitive and se- 
condary rocks in Suabia, Hungary, China, and South America. 
1058. M. Braconnot has successfully employed an ammoniacal so- 
lution of sulphuret of arsenic as a dye stuff; the process he recom- 
mends is as follows : 1 part of sulphur, 2 of white arsenic, and 5 of 
pearlash, are to be fused in a crucible at a heat a little below redness : 
a yellow mass results, which is to be dissolved in hot water and filtered ; 
the filtered solution, diluted with water, is to be treated with weak sul- 
phuric acid, and will give a fine yellow precipitate, which easily dis- 
solves in ammonia, forming a solution at first yellow, but becoming co- 
lourless on adding more ammonia. The wool, silk, cotton, or linen is 
to be dipped into this solution, more or less diluted according to the 
colour required, care being taken that no metallic vessels are used ; 
on taking them out they are at first colourless, but as the ammonia eva- 
porates become yellow; they are then to be freely exposed to the air, 
washed and dried. This colour is very permanent but soap impairs it. 
1059. Sulphuret of Arsenic and Iron is found native in many parts of 
Europe. It is of a more silvery colour than iron pyrites, and when 
heated exhales the odour of arsenic. It is called arsenical pyrites, or 
mis-pickel. 
1060. Nothing is known respecting the Sulphite or the Hyposulphite 
of Arsenic. 
1061. Sulphuric acid is slowly decomposed when boiled upon arsen- 
ic. Sulphurous acid is evolved, and difficultly soluble crystalline 
grains of sulphate of arsenic are deposited as the solution cools. 
1062. Phosphuret of Arsenic is formed by heating the metal, or its 
oxide, with phosphorus ; it is grey and brittle. 
1063. Neither the Hypophosphite nor Phosphite of Arsenic have been 
examined. 
1064. Phosphate of Arsenic is formed in difficultly soluble crystalline 
grains, by boiling white arsenic in phosphoric acid. 
1065. There appears to be no Carbonate of Arsenic. 
1066. Arsenic forms alloys with most of the metals, and they are 
generally brittle. With potassium it forms a brownish compound, 
which, when put into water, evolves less hydrogen than pure potas- 
sium, in consequence of the formation of hydruret of arsenic. With 
sodium, the alloy is either brown and of an earthy aspect, or grey and 
metallic, according to the proportions of the metals : water acts upon 
it as upon the former. (Gay-Lussac and Thenard, Recherches Physico- 
Chimiques, Tom. i.) The alloy of arsenic and manganese is not 
known. With iron, zinc, and tin, it forms white brittle compounds ; 
with copper it forms a white malleable alloy ; with lead, a brittle com- 
pound of a lamellar texture ; with antimony, the alloy is brittle, hard, 
and very fusible. It combines with bismuth, and probably with cobalt, 
but these alloys have not been examined. 
1067. The separation of arsenic from other metals may general!} 270 
MOLYBDENUM. 
be accomplished by deflagration with nitre, by which it is acidified, and 
the arseniate of potassa may afterwards be washed out by hot water. 
1068. As arsenic, either accidentally or intentionally taken, is a 
very frequent cause of death, and often the subject of judicial inquiry, 
it becomes of importance to point out the most effectual modes of dis- 
covering its presence. Where arsenic proves fatal, it is very seldom 
found in the contents of the stomach after death, but is generally pre- 
viously voided by vomiting or by stool; and we often can detect it in 
the matter thrown oft’ the stomach, in the form of a white powder, 
subsiding in water. The inflammation of stomach which results is gen- 
erally a secondary effect, and takes place equally, whether the poison 
be swallowed or applied to a wound. 
If minute quantities of white powder be detected, however, in the 
stomach after death, or in the matter vomited, it is to be carefully col- 
lected, and treated as follows : 
(a.) Mix a small portion of it with about two parts of black flux ; 
introduce the mixture into a glass tube, and gradually heat it red-hot 
in the flame of a spirit-lamp. If arsenic be present, a steel-coloured 
sublimate will attach itself to the cooler part of the tube, which, heat- 
ed in contact of air, evaporates in a white smoke, strongly smelling of 
garlic. 
(b.) Boil the suspected matter in a little distilled water : and when 
the solution has cooled, add a few drops of solution of sulphuretted 
hydrogen. If arsenic be present, a yellow precipitate will appear. 
(c) To the solution b add a drop of solution of subcarbonate of po- 
tassa and then a drop or two of solution of sulphate of copper. An ap- 
ple-green precipitate indicates arsenic. 
(d.) Add to the solution b a drop of nitrate of silver, and of solution 
©f ammonia. A yellow precipitate indicates arsenic. 
It must be observed in regard to these tests, that the first only is un- 
equivocal, and that the appearances produced by the others may ori- 
ginate from the presence of other substances. When, however, all 
the above appearances ensue, no doubt of the existence of arsenic can 
be entertained. The several precipitates should be collected, and will, 
when placed upon a red-hot iron, exhale the peculiar smell of arsenic, 
The reader is referred for further particulars on this subject to Hen- 
ry’s Elements of Chemistry, Vol. ii. p. 480, 8th edit. : to Murray’s 
System, Vol. iii. p. 441, 4th edit. : to Dr. Bostock’s Paper, in the 
Edinb. Med. andSurg. Journal, Vol. v. p. 166 : to Mr. Hume’s Essay, 
in the Phil. Mag. Vol. xxxiii. ; and London Med. and Phys. Journal, 
Vol. xxiii. : to Dr. Marcet’s Paper, in the Medico-Chirurgical Trans- 
actions, Vol. ii. ; and to Mr. Sylvester’s Observations, in Nichol- 
son’s Journal, Vol. xxxiii. 
Section XXIV. Molybdenum. 
1069. The sulphuret is the most common natural compound of this 
metal. To procure the metal, the native sulphuret is powdered and 
exposed under a red hot muffle, till converted into a grey powder, which NATIVE MOLYBDATE OF LEAD. 
ft to be digested in ammonia, and the solution filtered and evaporated 
to dryness. The residuum is dissolved in nitric acid, re-evaporated to 
dryness, and violently heated with charcoal. The metal is of a whit- 
ish grey colour, and of excessively difficult fusion. According to Hielm, 
its specific gravity is 7.4 ; according to Bucholz, it is as high as 8.6. 
1070. Molybdenum and Oxygen.—When exposed to heat and oxy- 
gen molybdenum is acidified, a white crystalline sublimate of molybdic 
acid being formed. 
There are two other compounds of molybdenum with oxygen ; the 
one brownish black, obtained by heating molybdic acid with charcoal; 
the other blue, and procured by immersing tin in solution of molybdic 
acid ; 
the black oxide consists of 47 M. -f* 8 oxygen 
the blue (molybdous acid) 47 M. -j- 16 
the white (molybdic acid) 47 M. -j- 24 
Mr. Hatchett, in his Experiments on the native Molybdate of Lead, 
concludes the metal to be susceptible of four degrees of oxidizement. 
—Phil. Trans., 1796. 
The above numbers are taken from the analyses of Bucholz, correct- 
ed by some experiments of my own, on the molybdic acid ; our results 
are very nearly similar. 
1071. To obtain molybdic acid, the native sulphuret should be tri- 
turated, to reduce it, as far as possible, to powder, and distilled, with 
three or four parts of nitre acid, to dryness. This operation should 
he repeated, till the ore is converted into an uniform white mass, which 
consists of molybdic, nitric, and sulphuric acids ; the two latter may 
be expelled by a red heat, in a platinum crucible, and the remaining 
molybdic acid repeatedly washed writh boiling water, in which it is little 
soluble, will be nearly pure. It may be rendered perfectly pure by 
solution in ammonia, precipitation by nitric acid, and exposure to heat. 
1072. The molybdic acid, thus procured, is a white powder, of the 
specific gravity of 3.46, and requiring 960 parts of boiling water for its 
solution, which is yellow, reddens litmus, but has no sour taste. Heat- 
ed to redness in an open vessel, it slowly sublimes, and condenses in 
brilliant yellowish scales. It dissolves in hot sulphuric acid, forming a 
Solution, which is colourless while hot, but on cooling acquires a blue 
colour, which is heightened by the addition of soda. Its muriatic solu- 
tion is pale yellowish green, but becomes blue when saturated by potas- 
sa.—Hatchett, Phil. Trans. 1796. 
1073. Mobybdate of Ammonia is not crystallizable, and when heated 
to redness the ammonia is driven off, and the acid converted into oxide 
of molybdenum.—Bucholz, Gehlen’s Journal, iv. 616. 
1074. Molybdate of Potassa is formed by digesting the acid in potas- 
sa ; or by heating to redness two parts of nitre with one of molybdic 
acid, and lixiviating the mass. The solution yields small rhomboidal 
crystals by evaporation, and affords a precipitate of molybdic acid, to 
muriatic, nitric, and sulphuric acids. 
1075. Molybdate of Soda is more soluble than molybdate of potassa, 
and furnishes permanent and transparent crystals. In obtaining both 
these salts, a deposit of a yellowish powder ensues, which is probably 
a bimolybdate of potassa and of soda. 
1076. Motive Molybdate of Lead occurs principally in crystals of PEROXIDE OF CHROMIUM. 
different shades of yellow. It was first discovered in Carinthia, and 
has since been found in Mexico, Hungary, and Saxony. According to 
Mr. Hatchett’s analysis {Phil. Trans. 1796,) it contains 38 molybdic 
acid + 58.4 oxide of lead ; and these numbers closely correspond with 
its theoretical composition, which should be 1 proportional of molybdic 
acid = 71 -f- 1 proportional of oxide of lead =112. 
1077. Molybdate of silver, of mercury of lead, and of nickel, may be 
procured by adding molybdic acid to the respective nitrates of those 
metals. 
The remaining molybdates have either not been examined, or the 
accounts of their properties are too much at variance to be depended 
upon. 
1078. Sulphuret of Molybdenum is a sectile compound of a metallic 
lustre, composed of 47 M. + 32 S. 
The native sulphuret is found in Bohemia, Sweden, and near Mont 
Blanc, disseminated in a grey granite. It has been found in England, 
chiefly in Cornwall; and in Scotland, in Inverness-shire. It rarely oc- 
curs crystallized ; generally massive, and made up of easily separable 
laminae. It is soft and unctuous to the touch, and in colour much like 
lead. It is found exclusively in primitive rocks ; generally in granite, 
and with quartz. 
1079. Little is known concerning the salts of molybdenum. 
Section XXV. Chromium. 
1080. Chromium was discovered by Vauquelinin 1797. Itmaybe ob- 
tained by intensely igniting its oxide with charcoal. Its colour resem- 
bles that of iron, and its specific gravity is 5.9. It is brittle and difficult 
of fusion. 
1081. Chromium and Oxygen.—When chromium is exposed to the 
action of heat and air, it combines with oxygen, and a green protoxide 
is obtained. This oxide easily dissolves in acids. 
1082. Native Protoxide of Chromium has been found in France, in 
the department of the Rhone, in the form of a green incrustation. It 
is the colouring matter of the emerald, and exists in a few other mine- 
rals. 
1083. When nitrate of chromium is decomposed at a red heat, an in- 
soluble brown deutoxide is formed. It does not dissolve in the acids ; 
but when heated with muriatic acid, chlorine is evolved, and a muriate, 
containing the protoxide, is formed. 
1084. Peroxide of Chromium, or Chromic acid, is most easily procur- 
ed by the decomposition of the native chromate of lead, which may be ef- 
fected by reducing it to a very fine powder, and boiling it in a solution 
of potassa or soda. An orange-coloured solution of the alcaline chro- 
mate is thus formed, to which sulphuric acid is to be added. On eva- 
poration chrystals of chromic acid are formed, along with the sulphate 
of soda or of potassa. Or the acid may be obtained by adding nitrate 
of baryta to the chromate of potassa, and subsequently decomposing the 
chromate of baryta which falls, by sulphuric acid. CHROMATES. 
1085. Chromie acid may also be procured by the following process 
from native chromate of iron, which is a more common mineral than 
the chromate of lead. Reduce it to a fine powder, and expose it to a 
red heat for two hours, mixed with half its weight of nitre ; wash the 
contents of the crucible, and add to the lixivium nitric acid sufficient to 
neutralize the excess of potassa: in this way a solution of nitrate and 
of chromate of potassa is obtained. Upon adding nitrate of mercury to 
this solution, chromate of mercury is precipitated in the form of a red 
powder, which, when washed, dried, and heated, is decomposed, and 
either chromic acid or oxide is obtained. 
1086. Chromic acid is of a red colour ; its taste is sour and metal- 
lic, and it may be obtained from its aqueous solutions in prismatic crys- 
tals, of a ruby colour. When heated red hot, it gives out a portion of 
oxygen, and becomes the green protoxide ; it imparts colour to the 
ruby. 
1087. Native Chromate of Iron has been found in small crystalline 
grains, of an octoedral form. It commonly occurs massive, of a black 
colour, with a slight metallic lustre, and hard enough to cut glass. It 
has been found in Siberia, Franee, and America, and promises to become 
useful in the arts, as a source of some fine pigments. 
1088. Native chromate of Lead is a very rare mineral, hitherto only 
found in the Uralian mountains in Siberia ; it occurs in prismatic crys- 
tals, of a fine orange red colour, and is occasionally accompanied by 
small green crystals, supposed to be chromite of lead, or a combination 
of oxide of chrome and oxide of lead. 
1089. Satisfactory experiments on the composition of the oxides of 
chromium are still wanting. According to Vauquelin, chromate of 
baryta consists of 62.2 baryta + 37.4 chromic acid, or, speaking in 
the equivalent numbers adopted in this work, of 1 proportional of 
baryta = 78 -f- 1 proportional of chromic acid 46.9. 
According to Berzelius, the green oxide of chromium contains half 
the quantity of oxygen existing in the chromic acid. If, therefore, the 
latter be regarded as a deutoxide, the number 30.9 will represent 
chromium, and protoxide of chromium would consist of 30.9 chro- 
mium-1- 8 oxygen; and chromic acid of 30.9 chromium + 16 oxy- 
gen. 
1090. The chromates of ammonia, potassa, soda, lime, and magne- 
sia are soluble and crystallizable, and of an orange colour. The 
chromates of baryta and strontia are difficultly soluble, and may be 
termed by adding chromate of potassa or soda to their soluble saline 
compounds. The other insoluble metallic chromates may be formed 
in the same way, and their colours, which are various and beautiful, 
often enable us to judge of the nature of the metal present. Thus 
chromate of soda forms insoluble precipitates in solutions of silver, 
mercury, lead, copper, iron, and uranium ; the colours are crimson, 
red, orange or yellow, apple-green, brown, and yellow. It forms no 
precipitate in solutions of nickel, zinc, tin, cobalt, gold, or platinum ; 
whence, perhaps, it may be inferred, that the chromates of the latter 
metals are soluble. 
The chromates are decomposed by muriatic, nitric, and sulphuric 
acids. Muriatic acid, heated with the chromates, evolves chlorine, 
the chromic acid being reduced to the state of oxide. 
The most correct details respecting the chromat.es that have been tuncstic acid. 
published, are to be found in Vauquelin’s Essay.—Annalcs de Chimie. 
Ixx. 
1091. The green oxide of chromium is occasionally used in porce- 
lain and enamel painting ; and the artificial chromate of lead forms a 
rich and durable yellow. 
The remaining compounds of chromium are as yet unexamined. 
Section XXVI. Tungsten. 
1092. This metal is obtained by exposing a mixture of tungstic acitl 
and charcoal to a strong beat. It is difficult of fusion, very hard, brit- 
tle, and of an iron colour. Its specific gravity 17.5. By the action of 
heat and air, tungsten is converted into an oxide, which is of a yellow 
colour. It has been called by some Scheelium, by others wolframium. 
1093. Peroxide of Tungsten, or Tungstic Acid, maybe obtained from 
two native combinations ; the one called wolfram, the other tungstate of 
lime. 
Wolfram is found in primitive countries generally accompanying 
tin ores ; its colour is brownish black; it occurs massive and crystal- 
lized, its primitive form being a rectangular parallelopiped. It abounds 
in Cornwall. It consists of tungstic acid united with oxides of iron, and 
and manganese. It may be decomposed by ignition with three times its 
weight of nitre ; the fused mass, digested in boiling water and filtered, 
furnishes a solution, which upon the addition of muriatic acid, gives a 
precipitate regarded by Scheele as tungstic acid, but which in fact is a 
compound of muriatic and tungstic acids and potassa. Dissolve this in 
boiling carbonate of potassa, precipitate by muriatic acid, wash the 
precipitate, and digest it in nitric acid. Then wash and dry it, and it is 
pure tungstic acid.—Bucholz, as quoted by Thomson, System, ii. 122. 
1094. Native Tungstate of Lime is a whitish semi-transparent sub- 
stance, found in England, Saxony, Bohemia, and Sweden, and occurring 
crystallized and massive. Its most usual form is the octoedron. It 
may be decomposed by fusion with four parts of carbonate of potassa, 
the fused mass is digested in about twelve parts of boiling water, and 
filtered. Nitric acid precipitates the peroxide. 
1095. Tungstic Acid, or Peroxide of Tungsten, is tasteless and insol- 
uble in water ; its specific gravity is 6. When violently heated it be- 
comes green, grey, and black, probably from the loss of oxygen. It 
combines with several of the metallic oxides, and was found by Guyton 
to give considerable permanence to vegetable colours ; hence it pro- 
bably might prove useful in the art of dyeing, were it more abundantly 
procurable. 
According to Dr. Thomson (System, Vol. i. p. 553,) tungstic acid is a 
compound of 
Tungsten 100 
Oxygen 25 
and h§ regards it as containing one proportional of metal and three of TUNGSTATE op manganese. 
oxygen. Upon these data the number 90 would represent tungsten and 
the peroxide would contain. 
96 
tungsten (one proportional) 
24 
oxygen (three proportionals) 
120 
tungstic acid. 
And tungstate of lime would consist of 
1 proportional of tungstic acid = 120 
1 lime = 28 
148 
but this does not agree with Klaproth’s experiments, who found tung- 
state of lime to consist of 
77.5 
22.5 
acid 
lime 
100 
though it is consistent with Berzelius’s statement, as reported by Thom- 
son, and which probably is founded on calculation. 
Some of the tungstates have been examined by Scheele, and others 
by Vauquelin and Hecht (Journal ties Mines, No. 19,) but their history 
remains very imperfect. 
1096. Tungstate of Ammonia is procured in crystalline scales, of a 
metallic taste, by digesting the acid in ammonia or its carbonate, ft 
contains, according to Vauquelin, 78 of acid, and 22 ammonia and wa- 
ter. 
1097. Tungstate of Potassa is uncrystallizable and deliquescent. 
The acids occasion precipitates in its solution, which are triple com- 
pounds of tungstic acid, potassa, and the acid used as precipitant. The 
JVitrotungstate of Potassa is the salt originally described by Scheele as 
tungstic acid. It dissolves in 20 parts of water, at 212°, and reddens 
litmus. 
1098. Tungstate of Soda crystallizes in hexaedral tables, soluble in 
4 of cold, and 2 parts of boiling water, and of an acrid taste. Sul- 
phuric, nitric, and muriatic acids occasion precipitates, as in the tungs- 
tate of potassa. 
1099. Tungstate of Lime, of Baryta, and of Strontia, are insoluble 
white compounds. 
1100. Tungstate of Magnesia is obtained by boiling the acid with 
magnesia, filtering, and evaporating; it cystallizes in pearly scales. 
The acids produce precipitates of triple compounds in its solution. 
1101. Tungstate of Manganese, formed by adding tungstate of po- 
tassa to muriate of manganese, is an insoluble white powder (John, 
Gehleri’s Journal, iv.) Tungstate of Iron is also insoluble : Tungstate 
of Zinc and of Tin have not been examined, nor have any of the re- 
remaining tungstates been examined in their pure state. 
The remaining compounds of tungsten have scarcely been investi- 
gated, an<j appear of little interest or importance. COLUMBATE OF POTASSA. 
Section XXVII. Columbium. 
1102. This metal was first discovered by Mr. Hatchett in a mineral* 
from North America. It is found combined with the oxides of iron and 
manganese, and also with yttria, in the minerals called tantaiite and 
yttro-tantalite. 
1103. Tantaiite is chiefly found in octoedral crystals, and in masses 
of a black or grey colour, in Finland. Its specific gravity is 7.9, and it 
contains, according to Ekeberg, 
80 oxide of columbium 
12 oxide of iron 
8 oxide of manganese. 
1104. Yttro-tantalite is found in Ytterby, in Sweden. It. contain a 
about 45 per cent, of oxide of columbium. Its colour is dark grey, its 
lustre shining and somewhat metallic. 
1105. Columbium was discovered in these minerals by M. Ekeberg, 
and, considering it as a new metal, he called it tantalum. In 1809 {Phil. 
Trans.) Dr. Wollaston examined these and the original mineral in the 
British Museum, and demonstrated the identity of columbium and tan- 
talum. As the former name was given to this body by its original dis- 
coverer, it is here retained. 
1106. Columbium may be procured from columbite or tantaiite, by 
the following process : Mix 5 parts of the finely-powdered mineral with 
25 of carbonate of potassa, and 10 of borax ; fuse the mixture, and 
when cold digest it in muriatic acid ; this dissolves every thing except 
the oxide of columbium, which remains in the form of a white powder 
(Wollaston, Phil. Trans. 1809, p. 248.). From 5 grains of colum; 
bite, Dr. Wollaston obtained 
Oxide of columbium 4 grain's 
iron a 
manganese £ 
From 5 grains of tantaiite he procured 
Oxide of columbium 4’ grain's 
iron h 
manganese T\ 
1107. Berzelius is the only person who has obtained metallic colum- 
bium. He describes it as having the colour of iron, very hard and 
brittle, and burning at a red heat into a whitish oxide. 
1108. The characters of white oxide of columbium are very well 
marked. It is nearly insoluble in muriatic, nitric, and sulphuric acids ; 
it is very soluble in potassa, and carbonate of potassa ; 8 grains of the 
latter, fused with 1 of the oxide, render it soluble in water. It is much 
less soluble in soda, and only retained while hot. From the readiness 
with which this .oxide combines with pot.assa, Mr. Hatchett called it co.- 
lumbic acid. 
1109. Colurnbate of Potassa, Us appears from Mr. Hatchett’s cxpe'ri-  OF NICKEL. 
meats, forms white glittering scales, like boracic acid. Acids precipi- 
tate the columbic acid from this solution. 
1110. Infusion of galls, added to the solution of columhate ofpotaS- 
sa produces a very characteristic orange-coloured precipitate. Nei- 
ther ferro-cyanate of potassa, nor hydrosulphurets, occasion any change. 
There is a character very peculiar to the oxide of columbium, which 
is its ready solubility, in tartaric, citric, and oxalic acids. In all these 
cases the newly precipitated oxide must be used, for when dried it be- 
comes very intractable. 
1111. According to Berzelius, 100 parts of columbium combine with 
5.485 of oxygen ; so that the representative of the metal in our num- 
bers will he 145.8, and of the oxide 145.8 + 8 = 153.8—Thomson , 
Vol. i. p. 568. 
The remaining properties of columbium have not been investigated. 
Section XXVIII. Nickel. 
1112. Nickel is found native ; combined with arsenic ; and with ar- 
senic acid. It is procured pure by the following process : Dissolve 
the impure metal, sold under the name of Speiss, in sulphuric acid, by 
adding the quantity of nitric acid necessary to produce the solution. 
Concentrate this solution, and set it aside ; fine green crystals of sul- 
phate of nickel make their appearance. Proceed in this manner till 
you have obtained a sufficient quantity of crystals. Dissolve them in 
water, and crystallize a second time. If they be now dissolved in wa- 
ter, and decomposed by an alcali, pure oxide of nickel will fall. Mix 
it with 3 per cent, of resin, make it into a paste with oil, and expose it 
to the most violent heat of a forge, in a charcoal crucible. A button of 
pure nickel will be obtained.—Thomson’s System, i. 391. 
1113. Nickel is a white metal, which acts upon the magnetic needle, 
and is itself capable of becoming a magnet. It is difficultly fusible, but 
absorbs oxygen readily when heated red-hot. It is malleable, and its 
specific gravity is about 8.5. 
1114. Oxide of Nickel is obtained by adding potassa to the solution 
of the nitrate ; a precipitate falls of a pale green colour which is a hy- 
drate, or compound of oxide of nickel with water; this heated to red- 
ness, affords a grey oxide, consisting, according to Tuputi (Annalcs dc 
Chimie, lxxx.) of 100 metal -f* 27 oxygen ; or, in our equivalents, of 
29.63 nickel 4* 8 oxygen = 37.63*. 
This protoxide of nickel easily dissolves m ammonia forming a sap- 
phire blue solution ; this property is often made use of to separate ox- 
ides of nickel and iron, the latter being insoluble in ammonia. 
1115. According to Thenard, if chlorine be passed through a mix* 
* Brandt has given no Reason why he prefers Tuputi’s experiments to those of Proust, Rich- 
ter, Klaproth, &c. who respectively give 26. 28.2 and 32.5 for the oxygen united to 100 metal. 
Thomson in his chemistry deduces the atom of nickel from Tuputi’s composition of the sul- 
phate, and makes it 28 when hydrogen=l. But the atom deduced from the chloride and sul- 
phate here given, is almost exactly—30. SrrVHATE OF AMMONIA AND NICKEL. 
ture of the hydrate of nickel and water, a black peroxide is formed, 
which, when acted upon by the acids, evolves oxygen, and returns t* 
the state of protoxide, 
1116. Chloride of Nickel.—-When nickel is heated in chlorine a chlo- 
ride results. This compound may also be obtained by heating muriate 
of nickel to redness in a glass tube ; a yellow scaly body is obtained, 
consisting of 55.5 nickel ff- 67 chlorine, or 29.8 (1 proportional nickel) 
-f- 36 (1 proportional chlorine.) 
1117. Muriate of Nickel, formed by dissolving the oxide or carbo- 
nate of nickel in muriatic acid, is obtained by evaporation in a confus- 
edly crystalline mass, of an apple-green colour and sweetish taste j it 
is soluble in about 2 parts of water at 60°. 
1118. Chlorate of Nickel.—Not examined. 
1119. Iodide of Nickel may be formed by adding solution of hydrio- 
date of potassa to sulphate or nitrate of nickel; it is of a greenish yel- 
low colour, and insoluble. 
1120. Iodate of Nickel has not been examined. 
1121. Nitrate of Nickel is a green deliquescent salt, difficultly erys- 
tallizable in rhomboids. The analyses of this salt are much at variance, 
but it probably consists of 1 proportional of each of its components, or 
37.8 oxide of nickel 
54 nitric acid 
91.8 
The crystals contain 3 proportionals of water. 
1122. By adding excess of ammonia to nitrate of nickel, and evapo- 
rating, green crystals of ammonio-nitrate of nickel are obtained, the so- 
lution of which affords no precipitate with potassa or soda. 
1123. Sulphuret of Nickel may be formed by fusion. It is a brittle 
yellow compound. 
1124. Neither the Hijposulpite nor the Sulphite of Nickel have been 
examined. 
1125. Sulphate of Nickel is formed by digesting the oxide in dilute 
sulphuric acid. A bright green solution is formed, which affords quad- 
rangular prismatic crystals, soluble in about 3 parts of water at 60®, 
and which effloresce by exposure. Their taste is sweet and astringent, 
This salt is also obtained by heating common nickel in sulphuric acid, 
with the occasional addition of nitric acid. (1112.) 
The crystallized sulphate of nickel contains 7 proportionals of water, 
and is composed as follows : 
1 
proportional of oxide 
= 37.86 
1 
acid 
= 40 
7 
water 
= 63 
140.86* 
1126. Sulphate of Ammonia and Nickel is formed by evaporating a 
mixed solution of ammonia, and sulphate of nickel; it forms four-sided 
prismatic crystals. 
* According; to the composition of the sulphate as determined by Tnputi, (see Thomson'! 
chan, article nickel) the acid is to the oxide as 40 : 34.9, and not as 40 : 37.86. METEORIC STONES. 
1127. Sulphate of potassa and Nickel is obtained by adding potassa to 
.sulphate of nickel (not in excess,) filtering and evaporating. It forms 
green rhomboidal crystals. 
1128. Sulphate of Nickel and Iron is formed by dissolving the mixr 
ed protoxides in sulphuric acid. It is a green efflorescent salt, in ta- 
bular crystals. 
1129. Sulphuretted hydrogen and hydrosulphuret of ammonia pro- 
duce a black precipitate of hydrosulphuretted oxide of nickel, when add- 
ed to the solution of the metal. 
1130. Phosphuret of Nickel is a brittle whitish compound. 
1131. Hypophosphite and Phosphite of Nickel remain unexamined. 
1132. Phosphate of Nickel being nearly insoluble, is precipitated, 
upon adding phosphate of soda to a solution of nickel. It is of a pale 
green colour. 
1133. Carbonate of Nickel is precipitated in the form of a green 
powder, when carbonate of potassa is added to sulphate of nickel. 
It is probably a compound of 1 proportional of each of its components. 
35.5 
20.7 
oxide of nickel 
carbonic acid 
5G,2 
1134. Borate of Nickel is a pale green insoluble compound. 
1135. Ferrocyanate of potassa occasions a very characteristic pale 
grey precipitate in dilute solutions of nickel: in concentrated solutions 
the precipitate is pale green. 
113G. Arseniateof potassa, dropped into nitrate of nickel, occasions 
the precipitation of a pale green arseniate of nickel. 
1137. The salts of nickel are distinguished by the fine green colour 
of their solutions, and by affording a green precipitate with ammonia, 
soluble in excess of that alcali, when it assumes a blue colour. The 
yellow green precipitate afforded by hydriodate of potassa is very 
characteristic of nickel; but the nicest test of its presence is the fer- 
rocyanate of potassa, which produces a pale grey or greenish white 
precipitate in all the solutions of the metal. 
1138. Of the Alloys of Nickel there is one which requires particu- 
lar notice, namely, that with iron, which forms the principal metallic 
ingredient in those lapideous masses, which, in different countries, 
have fallen upon our globe, and which have been termed aerolites, or 
meteoric stones. Though we really know nothing of the source or ori- 
gin of these bodies, it has been ascertained upon the most satisfactory 
and indisputable evidence, that they are not of terrestrial formation ; 
and, consequently, since men began to think and reason correctly, 
their visits to our planet have awakened much speculation, and some 
experimental research. 
In the first place, it deserves to be remarked, that we have very 
distinct evidence of the falling of stony bodies from the atmosphere 
in various countries, and at very remote periods. For, to say nothing 
of the fabulous narrations which encumber the annals of ancient Rome, 
or the extended catalogue of wonders flowing from the lively imagina- 
tion of oriental writers, such events are recorded in holy writ, and 
have been set down by the most accredited of the early historians; 
and although philosophic scepticism long contended against the admis- 
Meteor’s 
stones.' METEOKIG STOXES. 
sion of the fact, it has in modern times received such unanswerable 
proofs, as to be allowed by all who have candidly considered the evi- 
dence, and is only rejected by the really ignorant, or by those who, 
for the sake of singularity, affect disbelief. 
The first tolerably accurate narration of the fall of a meteoric stone 
relates to that of Ensisheim, near Basle, upon the Rhine. The ac- 
count which is deposited in the church runs thus : A.D. 1492. Wed- 
nesday, 7 November, there was a loud clap of thunder, and a child 
saw a stone fall from heaven : it struck into a field of wheat, and did 
no harm, but made a hole there. The noise it made was heard at Lu- 
cerne, Tilling, and other places ; on the Monday, King Maximilian or- 
dered the stone to be brought to the castle, and after having conversed 
about it with the noblemen, said the people of Ensisheim should hang 
it up in their church, and his Royal Excellency strictly forbade any 
body to take any thing from it. His Excellency, however, took two 
pieces himself, and sent another to Duke Sigismund of Austria. -This 
stone weighed 255 lbs. 
In 1627, 27th November, the celebrated Gassendi saw a burning stone 
fall on Mount Vaisir, in Provence : he found it to weigh 59 lbs. 
In 1672, a stone fell near Verona, weighing 300 lbs. And Lucas, 
when at Larissa, in 1706, describes the falling of a stone, with a loud 
hissing noise, and smelling of sulphur. 
In September, 1753, de Lelande witnessed this extraordinary phae- 
nomenon, near Pont de Vesle. In 1768, no less than three stones fell 
in different parts of France. In 1790, there was a shower of stones 
near Agen, witnessed by M. Darcet, and several other respectable 
persons. And on the 18th of December, 1795, a stone fell near Major 
Topham’s house, in Yorkshire ; it was seen by a ploughman and two 
other persons, Avho immediately dug it out of the hole it had buried 
itself in ; it weighed 56 lbs. 
We have various other, and equally satisfactory, accounts of the same 
kind. All concur in describing a luminous meteor, moving through the 
air in a more or less oblique direction, attended by a hissing noise, and 
the fall of stony or semi-metallic masses, in a state of ignition. Wq 
have, however, evidence of another kind, amply proving the peculiari- 
ties of these bodies. It is, that although they have fallen in very diffe- 
rent countries, and at distant periods, when submitted to chemical ana- 
lysis they all agree in component parts ; the metallic particles being 
composed chiefly of nickel and iron ; the earthy, of silica and magnesia. 
1139. Large masses of native iron (721) have been found in differ- 
ent parts of the world, of the history and origin of which nothing very 
accurate is known. Such are the great block of iron at Elbogen, in 
Bohemia; the large mass discovered by Pallas, weighing 1600 lbs., 
near Krasnorjark, in Siberia ; that found by Goldberry, in the great 
desert of Zahra, in Africa; probably, also, that mentioned by Mr. Bar- 
row, on the banks of the great flsh river in Southern AfriQa ; and. 
those noticed by Celis, Bruce, Bougainville, Humboldt, and others iu 
America, of enormous magnitude, exceeding 30 tons in weight. That 
these should be of the same source as the other meteoric stones, seems 
at tirst to startle belief; but when they are submitted to analysis, and 
the iron they contain found alloyed with nickel, it no longer seems 
credulous to regard them a? of meteoric origin. We find nothing of 
the kind in the earth. METEORIC STONES. 
1140. To account for these uncommon visitations of metallic and lu- 
pideous bodies, a variety of hypotheses have been suggested. 
Are they merely earthly matter, fused by lightning ? Are they the 
offspring of any terrestial volcano ? These were once fav ourite notions ; 
but we know of no instance in which similar bodies have in that way 
been produced, nor do the lavas of known volcanoes in the least resem- 
ble these bodies ; to say nothing of the inexplicable projectile force 
that would here be wanted. This is merely explaining what is puz- 
zling, by assuming what is impossible ; and the persons who have tak- 
en up this conjecture, have assumed one impossibility to account for 
what they conceive to be another, namely, that the stony bodies should 
come from any other source than our own globe. 
The notion that these bodies come from the moon, is, when impar- 
tially considered, neither absurd nor impossible. It is quite true, that 
the quiet way in which they visit us is against such an origin ; it seems, 
however, that any power which would move a body 6000 feet in a se* 
cond, that is, about three times the velocity of a cannon-ball, would 
throw it from the sphere of the moon’s attraction into that of our earth. 
The cause of this projective force may be a volcano, and if thus impel- 
led, the body would reach us in about two days, and enter our atmos- 
phere with a velocity of about 25000 feet in a second. Their ignition 
may be accounted for, either by supposing the heat generated by their 
motion in our atmosphere sufficient to ignite them, or by considering 
them as combustibles, ignited by the mere contact of air. 
While we are considering the possibility of these opinions, it may be 
remembered, that in the great laboratory of the atmosphere, chemical 
changes may happen, attended by the production of iron and other me- 
tals ; that, at all events, such a circumstance is within the range of pos- 
sible occurrences ; and that the meteoric bodies which thus salute the 
earth with stony showers, may be children of the air, created by the 
union of simpler forms of matter. The singular relationship between 
iron and nickel, and magnetism, and the uniform influence of meteoric 
phenomena on the magnetic needle, should be taken into account in 
these hypotheses. 
1141. Meteoric stones have generally an uneven black surface, and 
are internally of a grey colour and course texture. When carefully 
examined, they appear made up of a number of small spherical bodies 
and metallic grains imbedded in a softer matter, composed, according to 
Mr. Howard, (Phil. Trans., 1802.) of silica, magnesia, and iron with 
a little nickel: the spherical bodies are nearly of similar composition ; 
and the metallic grains are partly meteoric iron, and partly the same 
with a little sulphur. In addition to these substances, Vauquelin 
found 2 per cent, of chrome in a stone which fell at Langres, in 1815. 
(Ann. de Chim. et Phys., i. 53.) And Stromeyer detected cobalt in the 
meteoric iron from the Cape of Good Hope. (Thomson’s Annals, ix.) 
Lime and alumine have also been found in them, and a small proportion 
of manganese. M. Laugier has lately announced the existence of a mete* 
oric stone without nickel, but containing chrome ; and as he has detect* 
ed the latter metal in all the aerolites which he has examined, he con- 
siders it as their most characteristic ingredient.—Mem. du Museum, vi. 
1142. In meteoric iron the proportion of nickel varies considerably, 
In a specimen from the Arctic region I found 3.2 per cent. (Quarterly 
Journal, vi. 369.) In that from Siberia, Mr. Children found nearly I’EROXIDE OF MERCURY. 
JO per cent. The analysis may be performed by solution in nitro- 
muriatic acid ; the iron is thrown down by excess of ammonia in the 
state of peroxide, of which 100 grains indicate 70 of metallic iron ; it 
is separated by filtration, washed and dried, and on evaporating the fil- 
trated liquor and heating its dry x’esidue red-hot, the oxide of nickel 
is obtained, which should be re-dissolved in nitric acid and precipitated 
by pure potassa, the mixture being boiled for a few seconds. 100 
grains of this oxide of nickel are equal to 79 of metallic nickel.—Chil- 
dren, Quarterly Journal, ix. 324. 
1143. Meteoric iron has been imitated by fusing iron with nickel. 
The alloy of 90 iron with 10 nickel is of a whitish yellow cast, and 
not so malleable as pure iron. The alloy with 3percent, of nickel is 
perfectly malleable and whiter than iron. These alloys are less dis- 
posed to rust than pure iron, but nickel alloyed with steel increases 
the tendency to rust.—Stodart and Faraday, Quarterly Journal of 
Science and Arts, ix. 
1144. The remaining alloys of nickel have been little examined. 
Nothing is known of its compounds with potassium, sodium, manga- 
nese, zinc, or tin. With copper it forms a hard white alloy, which ap- 
pears to be the white copper of the Chinese. Its other alloys have not 
been examined. 
Section XXIX. Mercury. 
1145. The principal ore of this metal is the sulphuret, or native 
cinnabar, from which the mercury is separated by distillation with 
quicklime or iron filings. 
Mercury is a brilliant white metal, having much of the colour of 
silver, whence the terms hydrargyrum, argentum vivum, and quicksilver. 
It has been known from very remote ages. It is liquid at all common 
temperatures, solid and malleable at—40°, and it boils and becomes 
vapour at about 670°. Its specific gravity is 13.5. 
1146. Mercury is sometimes adulterated with the alloy of lead and 
bismuth, a fraud easily detected by the want of its due fluidity, and by 
its not being perfectly volatile, but leaving a residuum when boiled in 
a platinum or iron spoon. The best method of purifying mercury is 
to re-distil it in an iron retort. 
1147. Native Mercury occurs in small fluid globules, in most of the 
mines producing the ores of this metal. 
1148. Mercury and Oxygen.-—There are two oxides of mercury. 
The black, or protoxide, may be obtained by long agitation of the me- 
tal in contact with oxygen, or by washing the chloride of mercury 
(calomel) with hot lime-water. It is insipid, and insoluble in water, 
and was called in old pharmacy, Ethiops per se. 
1149. The red or peroxide of mercury is produced by exposing the. 
inetal, heated nearly to its boiling point, to the action of air. It be- 
comes coated with reddish brown scales, spangles, and crystals, and is 
ultimately entirely converted into a red shining mass, called in old phar- 
maceutical works, precipitate per se, or calcined mercury. It is the 
C.iiSttafcte!?#. PROTOCHLORIDE OF MERCERV. 
283 
'n/drargyri oxydum rubrum of the present London Pharmaeo- 
oosia. It is most easily obtained by introducing into a llat- 
bottomed matrass, of the annexed shape, about 4 ounces of 
mercury, and placing it in a sand bath, heated to the boiling 
point of the metal. In about a month’s time nearly the whole 
s converted into oxide. Air is freely admitted by the tube, 
while its length prevents the escape of mercurial vapour, 
which condenses and falls back into the body of the vessel; 
he remaining portion of running mercury may be driven off 
:>y exposing it in a basin to a heat just below redness. 
1150. Peroxide of mercury has an acrid metallic taste, and 
s poisonous ; it dissolves very sparingly in water. When 
iieated, it acquires a black colour, but becomes again red on 
moling ; at a red heat it evolves oxygen, and is reduced to the metallic 
state. It should be entirely volatilized when placed upon a red-hot iron, 
tor it is sometimes adulterated with red lead. 
1151. Though it is difficult to obtain a perfectly pure black oxide of 
mercury, it appears to have been demonstrated that it contains just hall 
the quantity of oxygen contained in the red oxide. 
The best analyses of the red oxide give as its component parts, 
Mercury . . . 
. . . 92.7 
Oxygen . . . 
7.3 
100.0* 
or more correctly 100 mercury 4- 8 oxygen. 
If vve consider this as a compound of 1 proportional of mercury and 
2 of oxygen, we obtain the number 200 as the representative of mer- 
cury ; for 
8 : 100 :: 16 : 200. 
The protoxide, therefore, will consist of 
200 Mercury -fr* 8 Oxygen = 208 Protoxide. 
And the peroxide of 
200 Mercury 4* 16 Oxygen = 216 Peroxide. 
The black oxide exists in thcpilula hydrargyria and in the mercuria 
ointment of the Pharmacopoeia. 
1152. Mercury and Chlorine combine in 2 proportions, and a proto- 
chloride and perchloride of mercury are the results. These compounds 
are usually called calomel and corrosive sublimate. In the London Phar- 
macopoeia they have received the improper names of submuriate of 
mercury and oxymuriate of mercury. 
1153. Protochloride of Mercury.—This compound, commonly termed 
calomel, is first mentioned by Crollius, early in the seventeenth centu- 
* This proportion would make but 7.87 oxygen unite to 100 mercury. Thomson, in his 
paper (Ann. Ph. for Aug. 1821.) has shown that the proportion is 100 mercury -f- 8 oxygen. 
In the saijie paper he states the experiirtent of SafstroDJ = 100 7.99. Thomson’* 
numbers will therefore be adopted. 284 
CHLORIDES OF MERCVRV. 
ry. The first directions for its preparation are given by Beguin, in 
the Tirocinium Chemicum, published in 1608. He calls it draco miti- 
gatus. Several other fanciful names have been applied to it, such as 
aquila mitigata, manna metallorum,panchymagogum minerale, sublima- 
tum dulce, mercurius dulcis, &c. 
The most usual mode of preparing calomel consists in triturating two 
parts of corrosive sublimate with one of mercury, until the globules 
disappear, and the whole assumes the appearance of an homogeneous 
grey powder, which is introduced into a matrass, placed in a sand heat, 
and gradually raised to redness. The calomel sublimes, mixed with u 
little corrosive sublimate, the greater part of which, however, being 
more volatile than the calomel, rises higher in the matrass ; that which 
adheres to the calomel may be separated, by reducing the w hole to a 
fine powder, and washing in large quantities of hot distilled water. 
Pure calomel, in the form of a yellowish white insipid powder, remains. 
It was formerly the custom to submit calomel to very numerous sub- 
limations, under the idea of rendering it mild ; but these often tended 
to the production of corrosive sublimate ; and the calomel of the first 
sublimation, especially if a little excess of mercury be found in it, is 
often more pure than that afforded by subsequent operations. 
1154. The following are the directions given in the last London 
Pharmacopoeia : 
“ Take of oxymuriate of mercury, 1 lb. 
purified mercury, by weight, 9 o 
Rub them together, until the metallic globules disappear ; then sub- 
lime : take out the sublimed mass, reduce it to powder, and sublime it 
in the same manner twice more successively. Lastly, bring it to the 
state of a very fine powder; throw this into a large vessel, full of 
water ; then stir it, and, after a short interval, pour the supernatant 
turbid solution into another vessel, and set it by, that the powder may 
subside. Lastly, having poured away the water, dry the powder.”— 
Powell’s Translation of the London Pharmacopoeia, Lond. 1815. p. 
144 and 99. 
1155. It will be observed, that in these processes the operation 
consists in reducing the perchloride to the state of protochloride by 
the addition of mercury. Various modes have, however, been adopt- 
ed for the direct formation of calomel: two of these may here be 
noticed, of which the first is in the humid way, as devised by Scheele 
and Chenevix. It is as follows : 
Form a nitrate of mercury, by dissolving as much mercury as pos- 
sible in hot nitric acid ; then dissolve in boiling water a quantity of 
common salt, equal to half the weight of the mercury used, and render 
the solution sensibly sour by muriatic acid, and pour the hot nitrate oP 
mercury into it. Wash and dry the precipitate. 
If this process be carefully performed, and the precipitate tho- 
roughly edulcorated, the calomel is sufficiently pure. 
1156. The second process, however, or that by which calomel is 
directly formed in the dry way, appears, on the whole, the least excep- 
tionable for the production of this very important article of pharma- 
cy ; it is the method followed at Apothecaries’ Hall, sanction having 
been obtained for its adoption from the College of Physicians. 
50 lbs. of mercury are boiled with 70 lbs. of sulphuric acid, tc dry- 
ness, in a cast-iron vessel: 62 lbs. of the dry salt are triturated with CHLORIDES OF MERCURY. 
40| lbs. of mercury, until the globules disappear, and 34 lbs. of com- 
mon salt are then added. This mixture is submitted to heat in earthen 
vessels, and from 95 to 100 lbs. of calomel are the result. It is to be 
washed in large quantities of distilled water, after having been ground 
to a line and impalpable powder. 
1157. Protochloride of mercury is usually seen in the form of a 
white mass, of a crystalline texture ; and when very slowly sublimed, 
it often presents regular four-sided prisms, perfectly transparent and 
colourless, its specific gravity is 7.2. It is tasteless and very nearly 
insoluble in water. It can scarcely be called poisonous, since in con- 
siderable doses it only proves purgative. By exposure to light it be- 
comes brown upon its surface. If scratched, it gives a yellow streak, 
which is very characteristic, and does not belong to the perchloride. 
When very finely levigated it becomes of a buff colour. 
It consists of 1 proportional of mercury 200 -f- 1 proportional of 
chlorine 36, and its representative number is 236. 
1158. Native Chloride of Mercury or mercurial horn ore, has been 
found in Germany, France, and Spain, usually crystallized, and some- 
times incrusting and massive. 
1159. Perchloride of Mercury, or corrosive sublimate, may be obtained 
by a variety of processes. 
When mercury is heated in chlorine, it burns with a pale flame ; the 
gas is absorbed, and a white volatile substance rises, which is the per- 
chloride. 
It may also be obtained by dissolving peroxide of mercury in muri- 
atic acid, evaporating to dryness, re-dissolving in water, and crys- 
tallizing. 
1160. The ordinary process for making corrosive sublimate consists in 
exposing a mixture of chloride of sodium (common salt) and persul- 
phate of mercury, to heat in a flask, or other proper subliming vessel; 
a mutual decomposition ensues. The chlorine of the common salt unites 
to the mercury of the sulphate, and forms bi-chloride of mercury. 
The oxygen of the oxide of mercury converts the sodium of the salt 
into soda, which, with the sulphuric acid, produces sulphate of soda. 
This decomposition is exhibited by the following diagram : 
1 proportional of perchloride of mercury —272. 
Chlorine 72 
Mercury 200 
2 proportionals 
of cofnmon salt 
—120 consist 
of 
1 proportional 
of persulphate 
of mercury =< 
2£6 consists of 
Sulphuric 
acid . . 80 
Sodium 48 
Oxygen 16 
2 proportionals of sulphate of soda = 144. 
1161. The following are the official directions of the London Phar- 
macopoeia, for the preparation of corrosive sublimate, there termed oxy- 
muriate of mercury 
“ Take of purified mercur}', hy weight, 2 lbs. 
sulphuric acid, by weight, 30 oz. 
—•—dried muriate of soda, 4 lbs. chlorides of aifcRctm. 
Boil the mercury with the sulphuric acid in a glass vessel, until the 
sulphate of mercury is left dry. Rub this when it is cold with the mu- 
riate of soda in an earthen-ware mortar; then sublime it in a glass cu- 
curbit, increasing the heat gradually.”—Powell’s Translation. 
The quantity of common salt employed in this process is obviously 
too large ; in practice, however, we find that more than the real quan- 
tity decomposed, and shown in the above table, is required. 
1162. The following is the process employed at Apothecaries’ Hall 
for the formation of corrosive sublimate : 50 lbs. of mercury are boiled 
to dryness with 70 lbs. of sulphuric acid. 73 lbs. of persulphate of 
mercury are thus formed, which being perfectly mixed with 120 lbs. of 
common salt and sublimed, yield from 63 to 65 lbs. of corrosive sub- 
limate. 
1163. By the quantity of chlorine absorbed by a given weight of 
mercury, we learn that the perchloride of mercury consists of 1 pro- 
portional of mercury = 200 4* 2 proportionals of chlorine ~ 72, con- 
sequently, its representative number is 272. 
1164. Perchloride of mercury is usually seen in the form of a per- 
fectly white semi-transparent mass, exhibiting the appearance of im- 
perfect crystallization. It is sometimes procured in quadrangular prisms. 
Its specific gravity is 5.2. Its taste acrid and nauseous, and leaving a 
peculiar metallic and astringent flavour upon the tongue. It dissolves 
in 20 parts of water at 60°, and in about half its weight at 212°. 
It is more soluble in alcohol than in water. When heated, it readily 
sublimes in the form of a dense white vapour, strongly affecting 
the nose and mouth. It dissolves without decomposition in muriatic, 
nitric, and sulphuric acids : the alcalis and several of the metals de- 
compose it. It produces, with muriate of ammonia, a very soluble 
compound ; hence a solution of sal-ammoniac is used with advantage 
in washing calomel to free it from corrosive sublimate. 
1165. Protochloride and perchloride of mercury are decomposed 
by potassa, soda, and lime ; the former affords black, (hydrargyri oxidum 
cinereum of the London Pharmacopoeia,) the latter red, oxide of mer- 
cury ; and the chlorides of potassium, sodium, and calcium, are pro- 
duced. The following diagrams shew the interchange of elements that 
takes place in the case of adding a solution of potassa to protochlo- 
ride and perchloride of mercury. 
1 proportional of chloride of potassium = 76. 
Chlorine 
36 
Potassium 
40 
1 proportional 
of protochlo- 
ride of mercu- 
ry 236. 
1 proportional 
of potassa s= 
48. 
Mercury 
200 
Oxygen 
8 
1 proportional of protoxide of mercury = 208. FROTONITRATE OF MERCERY. 
2 proportionals of chloride of potassium = 152. 
Chlorine 
72 
Potassium 
80 
1 proportional 
of perchloride 
of mercury = 
272. 
2 proportionals 
of potasya «= 
1K>. 
Mercury 
200 
Oxygen 
16 
1 proportional of peroxide of mercury =216. 
1166. When solution of ammonia is poured upon calomel, protoxide 
of mercury, and muriate of ammonia, are the results ; but ammonia, 
added to a solution of corrosive sublimate, occasions a white precipitate 
•f a triple muriate of ammonia and mercury. 
A compound of this kind has long been used in pharmacy, under the 
name of calx hydrargyri alba, or white precipitate. The London Phar- 
macopeia directs the follow process for its formation. 
“ Take of oxymuriate mercury £ lb, 
muriate of ammonia 4 oz. 
solution of subcarbonate of potassa \ pint* 
distilled water 4 pints. 
First dissolve the muriate of ammonia, then the oxymuriate of mercu- 
ry, in the distilled water, and add thereto the solution of subcarbonate 
of potassa. Wash the precipitated powder until it becomes tasteless ; 
then dry it.” 
1167. Muriate of ammonia renders corrosive sublimate more soluble 
in water, one part rendering five parts soluble in rather less than five 
of water. By evaporation a triple salt is obtained, formerly called sal- 
alembroth. The addition of potassa or soda throws down the above- 
mentioned white precipitate. Hence its use in washing calomel. 
1168. Chlorate of Mercury.—Chloric acid dissolves both the oxide?, 
of mercury ; the protochlorate has the appearance of a yellowish gra- 
nular powder, sparingly soluble in hot water, and of a mercurial taste. 
The perchlorate forms white acicular crystals, having the acrid flavour 
of the perchloride.-—Vauqueun, Annales de Chimie, xcv, 
1169. Mercury and Iodine unite in two proportions. These com- 
pounds may be procured either by gently heating mercury with iodine, 
or by adding hydriodic acid to solutions of mercury. The protiodido 
is yellow, and the periodide red. They respectively consist of 1 pro- 
portional of mercury -j- 1 of iodine and J 2. They are both inso- 
luble in water. 
1170. Iodate of Mercury.—Iodate of potassa occasions a precipitate 
in protonitrate of mercury, but not in the pernitrate. 
1171. Mercury and Nitric Acid,—Nitric acid is rapidly decomposed 
by mercury; nitrous acid, and nitric oxide gases are evolved, and 
either a protonitrate or a pernitrate of mercury are obtained, accord- 
ing to the mode in which the solution is performed. 
1172. Protonitrate of Mercury js best obtained by dissolving the 
metal in a cold and dilute acid, consisting of one part of acid and three 
jof water ; the metal should be added in small successive portions until 
*he acid ceases to act upon it, and care, should be taken to keep the. NITRATES OF MERCURV. 
whole cold. This solution deposits transparent crystals which appear 
to be modified octoedra, and which consist of the protoxide of mercury 
combined with nitric acid. They are soluble without decomposition in 
cold water, and the solution affords black precipitates of protoxide, 
upon the addition of the alcalis. 
1173. Pernitrate of Mercury.—When mercury ik dissolved in hot 
and concentrated nitric acid, it becomes peroxidised,and furnishes pris- 
matic crystals of the pernitrate. Their solution furnishes yellow or 
red precipitates of peroxide of mercury, upon the addition of potassa 
Or soda, and ammonia forms a white precipitate which is a triple nitrate 
of mercury and ammonia. 
When the precautions in forming the nitrates above described are 
not attended to, the solution usually contains a mixture of the two ni- 
trates, and furnishes a precipitate with the alcalis, composed of both 
oxides. The pernitrate is most certainly formed by dissolving the red 
oxide in nitric acid. 
1174. When hot water is poured upon pernitrate of mercury, a yel- 
low insoluble powder separates from it, v/hich is a subpernitrate, the 
nitrous turpeth of old writers ; and a super-pernitrate remains in solu- 
tion. It seems probable that the protonitrate is also capable of afford- 
ing a sub and a super nitrate ; but all these compounds have hitherto 
been but imperfectly investigated, and new researches are wanting to 
establish their nature and composition. 
If the protonitrate and pernitrate be composed of one proportional 
of each of the oxides with one of acid and with two of acid, the fol- 
lowing will be their component parts. 
208 protoxide 
54 nitric acid 
2G2 protonitrate of M. 
216 peroxide 
108 nitric acid 
324 
pernitrate of M. 
The subpernitrate has been analyzed by M. M. Braamcamp and 
Oliva, (Thomson, Vol. ii. p. 635), and they report its composition at 
12 acid 
88 peroxide 
100 
If its composition in theory be admitted as 2 proportionals of peroxide 
= 432 -f- 1 proportional of nitric acid = 54, these numbers are not 
much at variance with the above experimental result, thus, as 88 : 
12 : : 432 : 58. 
1175. When these nitrates of mercury are exposed to heat gradual- 
ly raised to dull redness, nitric acid is given off; and a brilliant red 
substance remains, consisting of peroxide of mercury with a small por- 
tion of adhering nitrate. This is used in pharmacy as an escharotic, 
and is called in the London Pharmacopoeia, hydrargyri nitrico-oxidum. 
In the manufacture of this compound at Apothecaries’ Hall, 100 lbs. 
of mercury are boiled w ith 48 lbs. of nitric acid (specific gravity 1.48), 
and by proper evaporation and application of a dull red heat, 112 lbs. 
of the hydrargyri nitrico-oxidum are obtained. HYPOSULPHITE OF MERCURY, 
1176. Mercury and Sulphur.—When one part of mercury is tritu- 
rated for some time with three of sulphur, a black tasteless compound 
is obtained, which was called in old pharmacy Ethiops Mineral; it 
is, however, no longer retained in the London Pharmacopoeia. 
The same substance is more readily formed by pouring mercury 
into melted sulphur, the substances quickly combine, with such a rise 
of temperature as often produces inflammation. 
1177. There is some difficulty in ascertaining how far these are de- 
finite compounds ; when, however, sulphuretted hydrogen is passed 
through a dilute solution of nitrate of mercury, a black powder is 
thrown down, which appears to be a true sulphuret, and which, accord- 
ing to Guibourt, (,Annales de Chimie, et Phys., Tom. i.) consists of 100 
mercury -f- 8*2 sulphur, numbers which nearly correspond to 
1 proportional mercury = 200 
1 sulphur = 16 
Sulphuret of mercury = 216 
1178. When the black sulphuret is heated red hot in a flask, a por- 
tion of mercury evaporates, and a sublimate of a steel grey colour is 
obtained, which, when reduced to a fine powder, assumes a brilliant 
red colour, and is called vermillion or cinnabar. It is, in fact, a bi- 
sulphuret of mercury, and consists of 
1 proportional of mercury 
= 200 
2 sulphur 
= 32 
Bisulphuret of mercury 
= 232 
1179. In the manufacture of cinnabar 8 parts of mercury are mixed 
in an iron pot with one of sulphur, and made to combine by a moderate 
heat, and constant stirring : this compound is then transferred to a glass 
subliming vessel, (on a small scale, a Florence flask answers perfectly), 
and heated to redness in a sand bath ; a quantity of mercury and of 
sulphur evaporate, and a sublimate forms which is removed, and rub- 
bed or levigated into a very fine powder. 
1180. Cinnabar is not altered by exposure to air or moisture ; when 
heated to dull redness in an open vessel, the sulphur forms sulphurous 
acid, and the mercury escapes in vapour. It is decomposed by distilla- 
tion with fixed alcalis, lime, and baryta, and by several of the metals. 
When adulterated with red lead it is not entirely volatile. 
1181. Cinnabar may be made in the humid way by long trituration of 
mercury and sulphur in solution of potassa.—Nicholson’s Journal, 
iv. to ii. 
1182. Native Cinnabar is the principal ore of mercury: it occurs 
massive and crystallized in six-sided prisms, rhombs, and octoedra. It 
is of various colours. sometimes appearing steel grey, at others bright 
red. It occurs in Hungary, France, and Spain, in Europe : in Siberia, 
and Japan, in Asia ; and in considerable quantities in South America. 
The mines of Almaden, and of New Spain, are the most productive, 
and furnish fine cabinet specimens. Native mercury, and native amal - 
gam of silver sometimes accompany it. 
1183. Hyposulphite of Mercury appears not to exist: when a solu- MERCURY AND PHOSPHORIC! AC11>. 
lion of a hyposulphite is poured into a very dilute solution of protoni- 
Irate of mercury it occasions a black precipitate. 
1184. Sidphite of Mercury has not been examined. 
1185. Mercury and Sulphuric Acid.—When mercury is boiled in its 
weight of sulphuric acid, sulphurous acid gas is evolved, a part of the 
metal is oxydized and dissolved, and a white deliquescent mass is ob- 
tained, which, washed with cold water, affords a very difficultly soluble 
white salt, which is a protosulphate of mercury. It requires 500 part6 
of water for its solution and crystallizes in prisms. According to Four- 
croy (Annales de Chimie, x.) it consists of 
12 sulphuric acid 
83 protoxide of mercury 
5 water. 
According to theory, it should consist of one proportional of sulphi- 
de acid -f- 1 of protoxide, or 
40 sulphuric acid 
208 protoxide of mercury 
248 sulphate of mercury. 
The alcalis precipitate black oxide of mercury from this salt. 
1186. If three parts of sulphuric acid be boiled to dryness with one 
of mercury, a white mass of persulphate of mercury is obtained; it is 
more soluble than the sulphate, and crystallizes in prisms. According 
to Braamcamp and Oliva, it is composed of 
31.8 acid 
63.8 peroxide 
4.4 water 
100.0 
It should consist, according to theory, of 1 proportional of peroxide 
4* 2 proportionals of acid. 
1187. When hot water is poured upon persulphate of mercury, a 
yellow insoluble subpersulphate is formed, formerly called Turpeth mine- 
ral. It appears to consist of 1 proportional of peroxide -f- 1 of acid, or 
216 peroxide of mercury 
40 sulphuric acid 
256 subpersulphate of mercury. 
A bipersulphate remains in solution. 
1188. The solutions of persulphate of mercury furnish red precipi- 
tates with the fixed alcalis, and white with ammonia, the latter being a 
triple sulphate of ammonia and mercury. 
1189. Sulphuretted hydrogen produces a black precipitate in solu- 
tions of mercury when added in excess, and which appears to be a sul- 
phuret of mercury. 
1190. Phosphuret of Mercury may be formed by heating phosphorus 
with oxide of mercury. It is a sectile solid of a bluish black colour. 
1191. Neither the Hypoposphite nor Phosphite of Mercury have been 
examined. 
1192. Mercury and Phosphoric Acid.—When phosphate of soda is TUNGSTATE OF MERCURY. 
291 
added either to nitrate or pernitrate of mercury, a white precipitate is 
formed. There is probably a protophosphate and a perphosphate. 
The latter is soluble in excess of acid. 
1193. Mercury and Carbonic Acid.—Alcaline carbonates produce 
buff-coloured precipitates in solutions of both oxides of mercury. 
These are probably the protocarbonate and the pcrcarbonate. 
1194. Mercury and Cyanogen.—By boiling one part of finely pow- 
dered red oxide of mercury with two of Prussian Blue, in eight parts 
of water, a solution is obtained, which, if filtered while hot, deposits, 
on cooling, yellowish white crystals in the form of quadrangular prisms, 
of a metallic taste and very poisonous, consisting, according to Gay- 
Lussac, of 80 mercury + 20 cyanogen. They are, therefore, a cyan- 
uret of mercury, and probably contain 1 proportional of mercury = 200 
-j- 2 of cyanogen = 48.8. 
1195. Cyanuret of mercury is decomposed by heat, as in the pro- 
cess for obtaining cyanogen ; and if distilled with muriatic acid, hydro- 
cyanic acid and chloride of mercury are formed. It also is decompos- 
ed by hydriodic acid and by sulphuretted hydrogen, an iodide and a 
sulphuret of mercury, and hydrocyanic acid, being formed. The alca- 
lis do not act upon this cyanuret. 
1196. Cyanuret of mercury is also formed by boiling peroxide of 
mercury in solution of ferrocyanate of potassa; a portion of mercury 
and of peroxide of iron are at the same time deposited, whence it ap- 
pears that the oxygen of the mercurial oxide is partly transferred to 
the iron, and partly to the hydrogen of the ferrocyanic acid. 
1197. Cyanuret of mercury boiled in water with peroxide of mer- 
cury produces a compound which forms small granular crystals con- 
sisting of cyanuret and oxide of mercury ; hence in making the cyan- 
uret by the above process (1194) excess of mercurial oxide should be 
avoided. 
1198. Borate of Mercury, obtained by adding borate of soda to ni- 
trate of mercury, is a yellow insoluble powder. 
1199. Arseniates of Mercury.—Arsenic acid occasions a pale yellow 
precipitate in solution of protonitrate of mercury, and a yellowish 
white precipitate in solution of the pernitrate. Arsenious acid pro- 
duces white precipitates in both solutions. 
1200. Molybdic acid occasions a white precipitate in solution of 
nitrate of mercury. 
1201. Chromate of Mercury.—Chromate of potassa throws down an 
orange-coloured precipitate from the solutions of nitrate and perni- 
trate of mercury. 
1202. Tungstate of Mercury.—Not examined. 
1203. The soluble salts of mercury furnish whitish precipitates 
with ferrocyanate of potassa, and black with sulphuretted hydrogen. 
A plate of copper, immersed into their solutions, occasions the separa- 
tion of metallic mercury. 
The insoluble mercurial salts are mostly entirely volatilized at a red 
heat; if distilled with charcoal, they afford metallic mercury. 
1204. Mercury combines with most of the other metals, and forms 
a class of compounds which have been called amalgams. These are 
generally brittle or soft. One part of potassium with 70 of mercury 
produce a hard brittle compound. If mercury be added to the liquid 
alloy of potassium and sodium (606), an instant solidification ensues, 
and heat enough to inflame the latter metals is evolved. The use of OSMIUM. 
an amalgam of zinc and mercury has already been adverted to for the 
excitation of electrical machines. (108.) The amalgams of gold and 
silver are employed in gilding and [dating. 
An amalgam of 2 parts of mercury, 1 of bismuth, and 1 of lead, is 
fluid, and when kept for some time, deposits cubic crystals of bismuth. 
Amalgam of copper may be made as follows : To a hot solution of 
sulphate of copper, add a little muriatic acid, and a few sticks of zinc, 
and boil the mixture for about a minute : by this means the copper 
will be precipitated in a metallic state, and in a finely divided spongy 
form: take out the zinc, pour off the liquor, wash the copper with 
hot water, and pour upon it a little dilute nitrate of mercury, which 
will instantly cover every particle of copper with a coating of mer- 
cury : then add to the amount of two or three times the 
weight of the copper, and a slight trituration will combine them so far 
that the completion of the process may be effected by heating the mix- 
ture for a few minutes in a crucible.—Aikin’s Dictionary, Art. Mercu- 
ry, p. 92. 
1205. When mercury is negatively electrized in a solution of am- 
monia, or when an amalgam of potassium and mercury is placed upon 
moistened muriate of ammonia, the metal increases in volume, and be- 
comes of the consistency of butter, an appearance which has sometimes 
been called the metallization of ammonia. The compound appears only 
to contain ammonia and mercury, though its real nature has not been 
satisfactorily ascertained. It has suggested some hypotheses concern- 
ing the nature of ammonia and the metals, which are not worth re- 
cording. 
Section XXX. Osmium. 
1206. Osmium, and the metals described in the three following sec- 
tions, are contained in the ore of platinum. This ore is digested in 
nitro-muriatic acid, by which the greater portion is dissolved, and there 
remains a black powder, which, when fused with potassa and washed, 
furnishes a yellow alcaline solution of oxide of osmium. Saturate the 
alcali with sulphuric acid, pour the mixture into a retort, and distil. A 
colourless solution of the oxide of osmium passes into the receiver ; it 
has a sweetish taste and a very peculiar smell, somewhat like that of 
new bread. When mercury is shaken with this solution it becomes an 
amalgam, which is decomposed by distillation, and pure osmium re- 
mains. 
1207. Osmium has a dark grey colour, and is not volatile when heat- 
ed in close vessels : but heated in the air it absorbs oxygen, and forms 
a volatile oxide. It has not been fused. 
1208. The leading characters of osmium are its insolubility in the 
acids, its ready solubility in potassa, the facility with which it is oxidized, 
the singular smell of its oxide, its great volatility, and the purple or blue 
colour produced in its solution by tincture of galls. The other com- 
pounds have scarcely been examined. 293 
RHODIUM 
Section XXXI. Iridium. 
1209. The black powder mentioned in the last section contains iri- 
dium, which resists the action of potass?, and consequently remains af- 
ter the separation of osmium. A solution of its oxide may be procur- 
ed by digesting it in muriatic acid, which first becomes blue, then olive- 
green, and lastly, red. By alternate treatment with potassa and mu- 
riatic acid, the whole of the black powder will be dissolved. By eva- 
porating the muriatic solution to dryness, dissolving the dry mass in 
water, and evaporating a second time, octoedral crystals of muriate of 
iridium are obtained. 
1210. Iridium is obtained by immersing a plate of zinc into a solu- 
tion of the muriate, or by violently heating the octoedral crystals. It is 
of a whitish colour, and, according to Mr. Children, who succeeded in 
fusing it by means of his large Voltaic apparatus, its specific gravity is" 
above 18. Its most marked character is extremely difficult solubility 
in the acids. 
1211. In crude platinum Dr. Wollaston discovered some flat white 
grains which resisted the action of the acids, and which he ascertained 
to consist of a native alloy of osmium and iridium. 
1212. Osmium and iridium were discovered by Mr. Tennant in 
1803. The name of the former is derived from the peculiar smell of 
its oxide ; that of the latter, from the variety of colours exhibited by 
its solution.—Phil. Trans., 1804. 
Section XXXII. Rhodium. 
1213. Rhodium and Palladium were discovered by Dr. Wollaston 
in 1803. These, like the two last described metals, exist in the ore 
of platinum, from which rhodium may be obtained by the following 
process : Digest crude platinum in a small quantity of nitro-muriatic 
acid, filter the saturated solution, and pour it into a solution of'sal 
ammoniac, by which the greater proportion of the platinum is precipi- 
tated. Decant the clear liquor and immerse a plate of zinc, which 
becomes coated with a black powder. Separate this and digest it in 
dilute nitric acid, by which a little copper and lead are taken up. 
Then wash and digest in dilute nitro-muriatic acid, to which add some 
common salt, evaporate to dryness, and wash the dry mass repeatedly 
with alcohol. A deep red substance remains, which, when dissolved 
in water, furnishes a black precipitate upon the immersion of a plate 
of zinc. This strongly heated with borax, assumes a white metallic 
lustre, and is rhodium. 
1214. Rhodium is very difficult of fusion ; its specific gravity is 
10.8. When an alloy of lead and rhodium is digested in nitro-muriatic 
acid, it is dissolved, and by evaporation a red compound is obtained, 
from which muriate of rhodium may be separated by water, or more 
perfectly by alcohol. The rose-colour of this compound suggested 
the name which has been applied to the metal. NATIVE SILVER. 
1215. Rhodium forms malleable alloys with the malleable metals, 
several of which have been examined by Dr. Wollaston.—Phil. Trans., 
1804. Thomson’s System, Vols. i. and ii. 
With steel, rhodium forms an alloy, which probably would be very 
useful in the arts, were it not for the scarcity of the latter metal. 1 
to 2 per. cent, of rhodium gives steel great hardness, and yet there is 
sufficient tenacity to prevent cracking either in forging or hammering. 
—Quarterly Journal, ix. 328. 
Section XXXIII. Palladium. 
1216. Palladium is most easily obtained by the following process. 
(Wollaston, Phil. Trans., 1805.) Digest the ore of platinum in 
nitro-muriatic acid, neutralize the redundant acid by soda, throw down 
the platinum by muriate of ammonia, and filter. To the filtered 
liquor add a solution of cyanuret of mercury (1194) ; a yellow floccu- 
lent precipitate is soon deposited which yields palladium on exposure 
to heat. 
1217. Palladium is of a dull white colour, malleable and ductile. 
Its specific gravity is about 11. It is hard. It fuses at a temperature 
above that required for the fusion of gold. 
1218. Dr. Wollaston has ascertained the existence of native palla- 
dium in the ore of platinum. It is in small fibrous grains. 
1219. Muriatic acid boiled upon palladium acquires a fine red colour. 
Sulphuric acid becomes blue. Nitric acid readily dissolves it; but its 
best solvent is the nitro-muriatic, which forms a fine red solution. 
The alcalis throw down an orange-coloured precipitate from these 
solutions, sparingly soluble in the alcalis. Ferrocyanate of potassa 
gives an olive-green precipitate; and sulphuretted hydrogen, one of 
a dark brown colour. 
Section XXXIV. Silver. 
1220. Silver is found native, and in a variety of combinations. 
Native Silver has the general characters of the pure metal. It oc- 
curs in masses; aborescent; capillary; and, sometimes, crystallized 
in cubes and octoedra. It is seldom pure, but contains small portions 
of other metals, which affect its colour and ductility. It is chiefly 
found in primitive countries. In Peru and Mexico are the richest 
known mines of native silver. The mines of Saxony, Bohemia, and 
Swabia, and those of Kongsberg in Norway, are the richest in Europe. 
It has been found in Cornwall and Devonshire. 
1221. Pure silver may be procured by dissolving the standard silver 
of commerce in pure nitric acid, diluted with an equal measure of 
water. Immerse a plate of clean copper into the solution, which soon 
Mode of ob- 
taining. OXIDE OP SILVER. 
295 
occasions a precipitate of metallic silver ; collect it upon a filter ; wash 
it with solution of ammonia, and then with water, and fuse it into a 
button. 
It may also be procured by adding to the above solution of standard 
silver a solution of common salt; collect, wash, and dry the precipi- 
tate, and fuse it with its weight of carbonate of potassa. A button of 
the pure metal is thus obtained. 
1222. Silver has a pure white colour, and considerable brilliancy. ( 
Its specific gravity is 10.5. It is so malleable and ductile, that it may 
be extended into leaves not exceeding a ten-thousandth of an inch in 
thickness, and drawn into wire finer than a human hair. 
1223. Silver melts at a bright red heat, and when in fusion appears 
extremely brilliant. It resists the action of air at high temperatures 
for a long time, and does not oxidize ; the tarnish of silver is occasion- 
ed by sulphureous vapours ; it takes place very slowly upon the pure 
metal, but more, rapidly upon the nllny with copper used for plate, and 
was found by Proust to consist of sulphuret of silver. Pure water has 
no effect upon the metal ; but if the water contain vegetable or ani- 
mal matter, it often slightly blackens its surface in consequence of the 
presence of sulphur. If an electric explosion be passed through fine 
silver wire, it burns into a black powder, which is an oxide of silver. 
In the Voltaic circle it burns with a fine green light, and throws off 
abundant fumes of oxide. Exposed to an intense white heat, it boils 
and evaporates. If suddenly cooled, it crystallizes during congela- 
tion, often shooting out like a cauliflower, and throwing small particles 
of the metal out of the crucible. 
1224. Silver is not unfrequently obtained in considerable quantities 
from argentiferous sulphuret of lead, which is reduced in the usual 
way and then cupelled; the oxide of lead thus procured is afterwards 
reduced by charcoal. 
Some of the silver ores, especially the sulphurets, are reduced by 
amalgamation. These ores, when washed and ground, are mixed with 
a portion of common salt and roasted ; it is then powdered and mixed 
by agitation with mercury, and the amalgam thus formed is distilled. 
The old process of eliquation is now scarcely used : it consisted in 
fusing alloys of copper and silver with lead ; this triple alloy was cast 
into round masses, which were set in a proper furnace upon an inclined 
plane of iron with a small channel grooved out, and heated red-hot, 
during which the lead melted out, and in consequence of its attraction 
for silver, carried that metal with it, the copper being left behind in 
a reddish black spongy mass.—Aikin’s Dictionary, Art. Silver. 
1225. Oxide of Silver may be obtained by adding lime-water to 
the solution of nitrate of silver, and washing the precipitate. It is of 
a dark olive colour, tasteless, insoluble in water, and when gently heat- 
ed, is reduced to the metallic state. 
The composition of oxide of silver has been very variously given, 
probably from the difficulty of obtaining it of similar purity. If its. 
composition be inferred from the chloride, or from the sulphuret, we, 
obtain the number 109.3 as the representative of silver, and the oxide 
will consist of 
Character. 
109.3 silver 
8 oxygen 
117.3 oxide of silver CHLORIDE OF SILVER. 
By a direct experiment upon the oxide of silver, precipitated bj 
potassa from the nitrate, it is found that 40 grains gave 7.9 cubical 
inches of oxygen, and 36.4 grains of silver remained ; the 7.9 cubic 
inches would weigh 2.686 grains, and 
Oxygen. 
Silver. 
Oxygen.. 
Silver. 
2.686 ; 
: 36.4 
:: 8 : 
108.4 
I have preferred the number 109.3 as being deduced from the chlo- 
ride, which is a more uniform compound than the oxide. 
1226. Mr. Faraday has rendered it probable that there is another 
combination of silver and oxygen, containing a smaller proportion of 
oxygen than the above, but it is not capable of combining with the acids. 
1227. Oxide of silver readily dissolves in ammonia, and by particu- 
lar management, a fulminating silver, composed of the oxide combined 
with ammonia, may be obtained. It was discovered by Berthollet, 
(Annales de Chimie, Tom. i.) The best process for obtaining it is to 
pour a small quantity of liquid ammonia upon the oxide ; a portion is 
dissolved, and a black powder remains, which is the detonating com- 
pound. It explodes when gently heated ; nitrogen and water are in- 
stantaneously evolved, and the silver is reduced. The oxide of silver 
should be perfectly pure and thoroughly edulcorated, and the ammonia 
quite free from carbonic acid. It should only be prepared in small 
quantities, and handled with the greatest caution, many accidents hav- 
ing arisen from its careless management. It sometimes explodes while 
still wet. 
1228. Silver and Chlorine.—Chloride of Silver.—This compound is 
easily procured by adding a solution of chlorine, of muriatic acid, or 
of common salt, to a solution of nitrate of silver : it falls in the form 
of a heavy insoluble tasteless powder, of a white colour, but which, by 
exposure to light, becomes brown, and ultimately black. When dry 
chloride of silver is heated to dull redness in a silver crucible it does 
not lose weight, but fuses ; and, on cooling, concretes into a grey se- 
mi-transparent substance, which has been called horn silver, or luna 
cornea. If slowly cooled, Proust has remarked that it has a tendency 
to octoedral crystallization. Heated to a bright red or white heat in 
an open vessel, it volatilizes in dense white fumes. 
1229. If fused with twice its weight of potassa or soda, chloride of 
silver is decomposed, and a globule of metallic silver is obtained. It 
is also rapidly decomposed by tin and zinc. Triturated with zinc tilings 
and moistened, the heat produced is so considerable as to fuse the re- 
sulting alloy of zinc and silver.—Faraday, Quarterly Journal of Sci- 
ence and Arts, viii. 374. 
1230. Chloride of silver is very soluble in ammonia, a circumstance 
by which it is usefully distinguished from some other chlorides, which, 
like it, are white, and formed by precipitation. We should be cautious 
in applying heat to the ammoniacal solution, as it sometimes forms a 
precipitate of fulminating silver. The ammoniacal solution furnishes 
crystals, which, when exposed to air, or put into water, lose their 
transparency, ammonia is evolved, and they crumble into chloride of 
silver. The fused chloride, exposed to ammoniacal gas, absorbs a con- 
siderable portion, which is given off by heat. If the dry chloride, thus 
saturated with ammonia, be thrown into chlorine, the ammonia sponta- 
Fulminating' 
silver. 297 
neously inflames. (Faraday, Journal of Science and Arts, Vol. v., p. 
75.) Chloride of silver is soluble in and decomposed by all the liquid 
hyposulphites. 
1231. As chloride of silver is insoluble in water, and very readily 
formed, it is often employed in analysis, as a means of ascertaining the 
proportion of chlorine present in various compounds. In these cases 
some excess of the precipitant should be used, and the precipitate 
allowed to subside previous to separating it upon the filter ; if the 
supernatant liquor become perfectly clear, the whole of the silver has 
fallen ; if it remain opalescent, a portion is probably still retained. 
The chloride in these cases should be perfectly dried in a silver cru- 
cible, up to incipient fusion. 
1232. The following are three of the best analyses of chloride of 
silver, and their close correspondence is no small test of their accu- 
racy. 
CHLORATE OF SILVER. 
Marcet. 
Gay-Lussac. 
John Davy. 
Silver . . 
, 75.47 . . 
, . . 75.25 . , 
. . . 75.5 
Chlorine 
£4.53 . . 
. . 24.75 . . 
. . . 24.5 
100.00 
100.00 
100.0 
The mean composition deduced from these experiments may be 
called 
Silver . . . . 
, . 75.4 
Chlorine . 
. . 24.6 
100. 
And we may accordingly, without material error, consider the chlo- 
ride of silver as composed of 
1 prop of silver = 
109.3 
1 chlorine = 
36. 
145.3 chloride of silver.* 
1233. Native Chloride of Silver has been found in most of the silver 
mines ; it occurs massive and crystallized in small cubes. 
1234. Chlorate of Silver is formed by digesting oxide of silver in 
chloric acid : it forms small rhombic crystals, which by the action of 
chlorine are converted into chloride of silver. 
1235. Muriatic acid has no action upon a piece of clean silver, un- 
less boiled with it for a long time, when a slight crust of chloride forms 
upon it. A beautiful experiment, illustrating the influence of electri- 
city on chemical action, consists in attaching a slip of silver to one of 
zinc, and putting the double bar into dilute muriatic acid ; the silver 
* Mr. Brande not having in this place, no more than in several others, assigned any au- 
thority for the determination he makes of the representative numbers, we must suppose it to 
rest on experiments of his own, though this is not said, and we therefore adhere to his pro- 
portions, only making here the due correction for chlorine. 
Thus as, 33.5 : 102.5 : : 36 : 109.3 
33.5 and 102.5 are the 
Num. of Brande. 
But we must observe, that in every case where the representative number is fractional, or an 
uneven integer, the accuracy of it is doubtful; for on a review of the multiples of hydrogen, 
they appear to be even integers. 298 
NITRATE OK SILVER. 
instantly acquires a crust of chloride in consequence of the negative 
energy imparted to it by the zinc, the latter metal being rapidly dis- 
solved. 
1236. Iodide of Silver is precipitated upon adding hydriodic acid to 
a solution of nitrate of silver. It is of a greenish yellow colour, in- 
soluble, and decomposed when heated with potassa. It is particularly 
characterized by insolubility in ammonia. 
1237. Iodate of Silver is precipitated in the form of a white powder 
by adding iodic acid or iodate of potassa to a solution of nitrate of sil- 
ver. It is very soluble in ammonia. 
1238. Nitrate of Silver.—Nitric acid, diluted with three parts of 
water, readily dissolves silver, with the disengagement of nitric oxide 
gas. If the acid contain the least portion of muriatic, the solution will 
be turbid, and deposit a white powder ; and if the silver contain cop- 
per, it will have a permanent greenish hue ; or if gold, that metal will 
remain undissolved in the form of a black powder. 
The solution should be perfectly clear and colourless ; it is caustic, 
and tinges animal substances of a deep yellow, which, by exposure 
to light, becomes a deep purple, or black stain, and is indelible, or 
peels off with the cuticle : it consists of reduced silver. It may be 
obtained in white crystals, in the form of four and six-sided tables, of 
a bitter and metallic taste, and soluble in about their own weight of 
water at 60°. It blackens when exposed to light, and when thus act- 
ed upon, is no longer perfectly soluble in water, owing to the separa- 
tion of a portion of metallic silver. 
1239. When heated in a silver crucible it fuses, and if cast into small 
cylinders, forms the lapis infernalis, or lunar caustic of pharmacy ; the 
argenti nitras of the Pharmacopoeia. In forming this preparation, care 
should be taken not to overheat the salt, and the moulds should be 
warmed. Exposed to a red heat, the acid is partly evolved and part- 
ly decomposed, and metallic silver obtained. 
1240. Sulphur, phosphorus, charcoal, hydrogen, and several of the 
metals, decompose this nitrate. A few grains mixed with a little sul- 
phur, and struck upon an anvil with a heavy hammer, produce a deto- 
nation ; phosphorus occasions a violent explosion when about half a 
grain of it is placed upon a crystal of the nitrate, upon an anvil, and 
struck sharply with a hammer ; and if heated with charcoal, it defla- 
grates, and the metal is reduced. 
If a piece of silk dipped into a solution of nitrate of silver be ex- 
posed while moist to a current of hydrogen gas, it is first blackened, 
and afterwards becomes iridescent from the reduction of portions of the 
metal.—Mrs. Fulhame’s Essay on Combustion. 
A stick of phosphorus, introduced into a solution of nitrate of silver, 
soon becomes beautifully incrusted with the metal, which separates 
upon it in arborescent crystals. A plate of copper occasions a bril- 
liant precipitation of silver, and the copper is oxidized and dissolved by 
the acid. 
1241. Mercury introduced into the solution of nitrate of silver, 
causes a beautiful crystalline deposit of silver, called the arbor Dianee: 
it was first remarked by Lemery. To obtain this crystallization in its 
most perfect state, the solution should contain a little mercury, and the 
mercury put into it should be alloyed with a little silver. Baumi? di- 
rects an amalgam of one part of silver with seven of mercury, of which 
Arbor dianae. HYPOSULPHITE OF SILVER. 
299 
a small piece is to be introduced into a solution composed of six drachms 
of saturated nitrate of silver and four drachms of a similar solution of 
mercury diluted with five ounces of distilled water; a small flask or 
matrass should be used for the experiment, kept perfectly at rest: in 
a few minutes small filaments of silver darken the surface of the amal- 
gam, and in about eight and forty hours the whole has separated in a 
shrub-like form. The principal use of the addition of mercury to the 
solution, and of silver to the precipitating mercury, is to give a degree 
of tenacity to the arborescent deposit of crystals, which prevents their 
falling to the bottom of the flask. 
1242. The alcaline metallic oxides decompose this salt of silver : it 
is also decomposed by muriatic, sulphuric, phosphoric, and boracic 
acid. The protosulphate of iron throws down metallic silver when 
added to a solution of the nitrate : protomuriate of tin forms a grey 
precipitate consisting of peroxide of tin and oxide of silver. 
1243. Ammonia added to solution of nitrate of silver occasions a 
precipitate soluble in excess of the alcali. 
1244. Nitrate of silver is of much use, as a test for chlorine, muri- 
atic acid, and their compounds. It is employed for writing upon linen 
under the name of indelible or marking ink, and is an ingredient in 
many of the liquids which are sold for the purpose of changing the co- 
lour of hair. It is used in medicine and surgery. 
1245. Nitrite of Silver is obtained, according to Proust, by long di- 
gestion of powdered silver in nitric acid already saturated with the 
metal. It is more soluble than the nitrate, and difficultly crystalliza- 
ble. It appears not improbable that this salt may contain the suboxide 
noticed by Mr. Faraday. (1226.) 
1246. Sulphuret of Silver.—Silver readily combines with sulphur, 
and produces a grey crystallizable compound, considerably more fusi- 
ble than silver. It is this which forms the tarnish upon silver plate. 
(1223) It consists of 1 proportional of each of its components. 
Silver . . 109.3 
Sulphur. 16. 
125.3 sulphuret of silver. 
1247. Sulphuretted hydrogen and hydrosulphuret of ammonia occa- 
sion a copious black precipitate of sulphuret of silver when added to 
solutions of the metal; a portion of the silver is frequently at the same 
time reduced to the metallic state. 
1248. Native Sulphuret of Silver, or vitreous silver ore, is found in 
various forms, and when crystallized, is in cubes, octoedra, and dode- 
eaedra. It is soft and sectile. The finest specimens are from Siberia. 
1249. A triple combination of silver and antimony with sulphur, con- 
stitutes the red or ruby silver ore; it is found massive and crystallized 
in hexaedral prisms. It consists of about 70 parts of sulphuret of sil- 
ver, and 30 sulphuret of antimony. It occurs in all the silver mines, 
and is sometimes accompanied by the brittle sulphuret of silver, or silver 
glance. 
1250. Hyposulphite of Silver has been examined by Mr. Herschel in 
his able paper on the hyposulphurous acid (Edin. Phil. Journal, i. 26.) 
It is formed by dropping a weak solution of nitrate of silver into a very 
dilute solution of hyposulphite of soda; a white cloud is at first produc- 300 
PHOSPHATE OF SILVER. 
ed, which re-dissolves on agitation ; on adding more of the precipitant, the 
cloud re-appears and aggregates into a grey precipitate, which appears 
to consist of hyposulphite of silver ; the supernatant liquor tastes in- 
tensely sweet, which is remarkable considering the disgusting bitterness 
both of the nitrate and of the hyposulphite, and shows, says Mr. Her- 
gchel, “ how little we know of the way in which bodies affect the or- 
gans of taste. Sweetness and bitterness, like acidity, seem to depend 
upon no particular principle, but to be regulated by the state of com- 
bination in which the same principles exist at different times.” 
Hyposulphite of silver is also produced when chloride of silver is 
dissolved in any of the hyposulphites ; the solution is intensely sweet 
without any metallic flavour. 
1251. Hyposulphite of Potassa and Silver is formed when liquid po- 
tassa is dropped into the solution of chloride of silver in hyposulphite 
of soda ; it separates in the form of a copious precipitate, which, when 
washed and dried, is found to consist of small grey pearly scales : they 
are difficultly soluble in water ; of a very sweet taste ; and heated be- 
fore the blow-pipe afford a bead of silver. 
1252. Sulphite of Silver is obtained in crystalline grains by digest- 
ing oxide of silver in sulphurous acid. 
1253. Sulphate of Silver is deposited when sulphate of soda is mix- 
ed with nitrate of silver. It is also formed by boiling silver in sulphu- 
ric acid. It requires about 90 parts of water at 60° for its solution ; 
in boiling water it is more soluble and*is deposited, as the solution cools, 
in small prismatic crystals : it is decomposed at a red heat. It consists 
of 
1 proportional of oxide of silver = 
117.3 
1 sulphuric acid = 
40 
157.3 sulphate of silver. 
1254. A compound acid, which may be called nitro-sulphuric, con- 
sisting of one part of nitre dissolved in about ten of sulphuric acid, dis- 
solves silver at a temperature below 200°, and the solution admits of 
moderate dilution before sulphate of silver separates from it. This 
acid scarcely acts upon copper, lead, or iron, unless diluted with wa- 
ter ; it is, therefore, useful in separating the silver from old plated ar- 
ticles : the precious metal may afterwards be separated either in the 
form of chloride, by adding common salt; or by diluting the acid and 
continuing the immersion of the pieces of copper which have lost their 
silvering, and which will now dissolve in the diluted acid and occasion 
the precipitation of metallic silver.—Keir, Phil. Trans., lxxx. 
1255. Phosphuret of Silver is a white brittle compound. 
1256. Neither Hypophosphite nor Phosphite of Silver have been ex- 
amined. 
1257. Phosphate of Silver is formed by dropping a solution of phos- 
phate of soda into nitrate of silver. It is of a yellow colour, and con- 
sists, according to Berzelius, (Annales de Chimie, et Physique, Tom. ii.) 
of 
83 
17 
oxide of silver 
phosphoric acid 
100 ALLOYS OF SILVER. 
301 
so that it may be considered as a compound of 1 proportional of oxide 
of silver = 117.3 -f- 1 proportional of phosphoric acid = 28. 
1258. Carbonate of Silver is precipitated in the form of a white in- 
soluble powder, by adding carbonate of potassa to nitrate of silver. It 
blackens by exposure to light. It consists of 
1 proportional of carbonic acid = 
22 
1 oxide of silver = 
117.3 
Carbonate of silver = 
139.3 
1259. Carbonate of ammonia only throws down a portion of the sil- 
ver from the nitrate, and forms a triple amrnonio-carbonate of silver. 
1260. Borate of Silver is thrown down from the nitrate of silver in 
the form of white powder, by adding solution of borate of soda. 
1261. Hydrocyanic acid and hydrocyanate of potassa cause a white 
precipitate in solutions of silver, which appears to be a cyanuret of sil- 
ver, and which, when heated, gives out cyanogen. 
1262. Arsenite of Silver is precipitated in the form of a white pow- 
der, soon becoming yellow and brown, by the addition of solution of ar- 
senious acid to nitrate of silver. 
1263. Arseniate of Silver is thrown down from nitrate of silver by 
arsenic acid, of a reddish brown colour. 
1264. Molybdate of Silver has not been examined. 
1265. Chromate of Silver is precipitated of a crimson colour by add- 
ing chromate of soda to nitrate of silver. It soon loses its brilliant 
tint and becomes brown. 
1266. Tungstate of Silver—not examined. 
1267. The soluble salts of silver are recognised by furnishing a 
white precipitate with muriatic acid, which blackens by exposure to 
light, and which is readily soluble in ammonia ; and by affording me- 
tallic silver upon the immersion of a plate of copper. The salts inso- 
luble in water are soluble in liquid ammonia, and when heated on char- 
coal before the blow-pipe they afford a globule of silver. 
1268. Alloys of Silver.—The compounds of this metal with potas- 
sium, sodium, and manganese, have not been examined. It unites dif- 
ticultly with iron. 
1269. When silver and steel are fused together, an alloy is formed, 
which appears perfect while in fusion, but globules of silver exude from 
it on cooling, which shows the weak attraction of the metals. At a 
very high temperature the greater part of the silver evaporates, but a 
portion equal to about 1 in 500 remains, forming a perfect alloy, admi- 
rably adapted to the formation of cutting instruments.—Stodart and 
Faradav, on the Alloys of Steel. Quarterly Journal, ix. 
1270 Silver readily combines with zinc and tin, forming brittle al- 
loys. The alloy of silver with copper is of the most importance, as it: 
constitutes plate and coin By the addition of a small proportion of 
copper to silver, the metal is rendered harder and more sonorous, 
while its colour is scarcely impaired. 
The standard silver of this country consists of 11 pure silver and 
A pound troy, therefore is composed of 11 oz. 2 dwts. 
pure silver, and 18 dwts. of copper, and it is coined into 66 shillings. 
With lead the alloy is grey and brittle, as also with antimony, bismuth, 
cobalt, and arsenic. 302 
ALLOYS OF SILVER. 
1271. Amalgam of silver is sometimes employed for plating; it is 
applied to the surface of copper, and the mercury being evaporated by 
heat, the remaining silver is burnished. The better kind of plating, 
however, is performed by the application of a plate of silver to the 
surface of the copper, which is afterwards beaten or drawn out. 
1272. A mixture of chloride of silver, chalk, and pearlash, is em- 
ployed for silvering brass : the metal is rendered very clean, and the 
above mixture, moistened with water, rubbed upon its surface. In 
this way thermometer scales and clock dials are usually silvered. 
1273. The analysis of alloyed silver is a very important process, 
and in continual practice by refiners and assayers. It may be per- 
formed in the humid way by dissolving the alloy in nitric acid, precipi- 
tating with muriatic acid, and either reducing the chloride by potassa 
in the way above described (1229), or estimating the quantity of silver 
which it contains. The usual method, however, which is employed at 
the mint, and by the refiners, is cupellation. 
1274. Of the useful metals, there are three only which are capable 
of resisting the action of air at high temperatures ; these are silver, 
gold, and platinum; the others, under the same circumstances, become 
oxidized ; it might, therefore, be supposed, that an alloy, containing 
one or more of the former metals, would suffer decomposition by mere 
exposure to heat and air, and that the oxidable metal would burn away. 
This, however, is not the case ; for if the proportion of the latter be 
small, it is protected, as it were, by the former ; or, in other cases, a 
film of oxide coats the fused globule, and prevents the further action 
of the air. These difficulties are overcome by adding to the alloy 
some highly oxidable metal, the oxide of which is fusible. Lead is 
the metal usually selected for this purpose, though bismuth will also 
answer. Supposing, therefore, that an alloy of silver and copper is to 
be assayed, or analyzed by cupellation : the following is the mode of 
proceeding. 
A clean piece of the metal, weighing about 30 grains, is laminated, 
and accurately weighed in a very sensible balance. It is then wrap- 
ped up in the requisite quantity of sheet lead, (pure and reduced from 
litharge,) and placed upon a small cupel, or shallow crucible, made of 
bone earth, which has been previously heated. The whole is then 
placed under the muffle, heated to bright redness ; the metals melt, 
and by the action of the air which plays over the hot surface, the lead 
and copper are oxidized and absorbed by the cupel, and a button of 
pure silver ultimately remains, the completion of the process being 
judged of by the cessation of the oxidation and motion upon the surface 
of the globule, and by the very brilliant appearance assumed by the 
silver when the oxidation of its alloy ceases. The button of pure 
metal is then suffered to cool gradually, and its loss of weight will be 
equivalent to the weight of the alloy, which has been separated by 
oxidation. 
To perform this process with accuracy, many precautions are re- 
quisite, and nothing but practice can teach these, so as to enable the 
operator to gain certain results. An excellent article upon the subject 
will be found in Aikin’s Chemical Dictionary, and in Mr. Children’s 
Translation of Thenard on Chemical Analysis. 
Silvering for 
dials. 
Assaying. CHLORIDE OF GOLD. 
303 
Section XXXV. Gold. 
1275. Gold occurs in nature in a metallic state, alloyed with a lit- 
tle silver or copper, and in this state is called native gold. Its colour 
is various shades of yellow; its forms are massive,ramose, and crys- 
tallized in cubes and octoedra. The veins of gold are confined to 
primitive countries, but large quantities of this metal are collected in 
alluvial soils and in the beds of certain rivers, more especially those 
of the west coast of Africa, and of Peru, Brazil, and Mexico. In Eu- 
rope, the streams of Hungary and Transylvania have afforded a respec- 
table quantity of gold ; it has been found also in the Rhine, the Rhone, 
and the Danube. Small quantities have been collected in Cornwall, 
and in the county of Wicklow in Ireland. 
1276. Gold may be obtained pure by dissolving standard gold in 
nitro-muriatic acid, evaporating the solution to dryness, re-dissolving 
the dry mass in distilled water, filtering, and adding to it a solution of 
protosulphate of iron ; a black powder falls, which, after having been 
washed with dilute muriatic acid and distilled water, affords on fusion a 
button of pure gold. 
1277. Gold is of a deep yellow colour. It melts at a bright red 
heat, and when in fusion appears of a brilliant green colour. 
Gold is so malleable that it may be extended into leaves which do 
not exceed of an inch in thickness. It is also very ductile. It 
shows no tendency to unite to oxygen when exposed to its action in a 
state of fusion ; but if an electric discharge be passed through a very 
fine wire of gold, a purple powder is produced, which has been con- 
sidered as an oxide. 
1278. Oxide of Gold may be obtained by adding a solution of potas- 
sa to a solution of muriate of gold, and heating the mixture ; the pre- 
cipitate must be washed first with weak solution of potassa, and then 
with water, and dried at a temperature of 100° ; if the heat exceed 
this, a portion of the oxide is reduced, and it is then only partially so- 
luble in muriatic acid. If this be regarded as a protoxide, that is, as 
consisting of 1 proportional of gold -f- 1 of oxygen, then the number 
103.44-7.5 : 97 : : 8 : 103.4 will represent gold, and this oxide will 
consist of 103.4 gold 4~ 8 oxygen =111.4*. It is, however, probable 
that the purple powder produced by the combustion of gold contains 
a portion of oxygen. 
1279. Chloride of Gold.—When gold in a state of minute divison is 
heated in chlorine, a compound of a deep yellow colour results, which 
is said to consist of 103.4 gold 4" 36 chlorine. When acted upon by 
water, a muriate of gold is produced. 
1280. The action of iodine on gold has been examined by M. Pelle- 
tier, (Quarterly Journal of Science and Arts, x. 121.) When hydrio- 
date of potassa is added to muriate of gold, it produces a very co- 
pious yellowish brown precipitate, insoluble in cold water, and easily 
decomposed by heat. It gave on analysis 
History. 
Mode of ob- 
taining. 
Characters. 
Salts of gold 
Iodine .... 
34 
Gold 
66 
*'Tbese numbers are deduced from Proust’s experiments.—Nicholson’s Journal, Voi, xiv NITHATC OF GOLD. 
If this be considered a compound of 1 proportional gold and 1 of 
iodine, the number 242.6 must be adopted as the representative of gold, 
for 34 : 66 :: *125 : 242.6, a number so much at variance with that 
deduced from other experiments, as to show the necessity of further 
inquiries, before either be adopted. 
1281. Nitrate of Gold.—The nitric acid has scarcely any action upon 
gold, but it readily dissolves the oxide, forming a yellow styptic deli- 
quescent salt. 
1282. The true solvents of gold are solution of chlorine and nitro- 
muriatic acid ; the latter is usually employed, composed of two parts of 
muriatic and one of nitric acid. By evaporation, the saturated solution, 
which, however, is always acid, affords prismatic crystals of muriate of 
gold. This salt is very deliquescent; it is decomposed by heat, leav- 
ing a spungy mass of pure gold ; a very minute portion of the metal 
also passes off with the muriatic acid. 
1283. When potassa is added to the solution of muriate of gold, no 
precipitate occurs till heat is applied, when a reddish-yellow precipi- 
tate falls, which is peroxide of gold (1278) ; the whole of the metal, 
however, is not thrown down, a portion being retained so as to form a 
triple muriate of gold and potassa, which is very soluble and not de- 
composed by further excess of alcali : it is on this account that a very 
acid solution of muriate of gold will afford no precipitate whatever with 
potassa or soda, the triple salt formed being in that case sufficient to em- 
ploy the whole of the oxide of gold. M. Pelletier has stated that 
potassa alone dissolves oxide of gold, and has called the compound au- 
rate of potassa. * 
1284. When liquid ammonia is added to a concentrated solution of 
muriate of gold diluted with about three parts of water, a yellowish- 
brown precipitate is formed, which if collected upon a filter, washed 
with a little water, and carefully dried at the temperature of 212°, is 
fulminating gold. Bergman first showed that this compound consists of 
about five parts of peroxide of gold and one of ammonia : when heated 
to about 400°, it explodes violently, the gold is reduced, and nitrogen 
and water are evolved ; hence it appears that the ammonia is decom- 
posed, that its hydrogen uniting with the oxygen of the oxide forms wa- 
ter, and that the nitrogen is suddenly liberated. It explodes by friction 
with hard bodies, and by an electrical shock. If two or three grains 
be detonated upon a thin piece of platinum leaf, the metal is torn at the 
point of contact. 
1285. Muriate of gold is decomposed by phosphorus and charcoal, 
and by sulphurous acid : a piece of paper, moistened with it and ex- 
posed to light, also becomes purple in consequence of its decomposition. 
1286. When solution of protosulphate of iron is added to muriate of 
gold the mixture instantly acquires a dingy green or brown tinge, and 
appears of a beautiful green if viewed by strong transmitted light: these 
appearances depend upon the presence of an infinite number of small 
particles of gold in the metallic state, its oxygen having been imparted 
to the salt of iron : they soon subside in the form of a brown powder, 
which may be collected upon a filter and fused into a button. This me- 
thod of separating gold from its solution is often convenient in analyti- 
cal operations. 
Triple muri- 
ate. 
Fulminating 
gold. 
* The number representing iodine, and the only one that is odd: probably incorrect. ALLOYS OF GOLD. 
1287. Protomuriate of tin, added to muriate of gold, occasions an 
instant change of colour to a reddish brown or dirty purple : if a piece 
of tin foil be immersed in a dilute solution of the muriate of gold, the 
same purple powder is presently thrown down upon it: this powder 
is used in enamel painting, and for tinging glass of a line red colour, 
under the name of purple of Cassius : it is a compound of peroxide of 
tin and oxide of gold, the latter metal appearing to be in a very low 
state of oxidizemcnt, and yet soluble in muriatic acid : it is also soluble 
in ammonia, forming a deep purple liquor. It would appear from 
Proust’s experiments to consist of about three parts oxide of tin, ancl 
one of oxide of gold. 
1288. If a solution of muriate of gold be mixed with sulphuric 
ether it combines with the oxide, and an ethereal solution of gold is ob- 
tained. Polished steel dipped into this solution acquires a coat of 
gold, and it has hence been employed for gilding delicate cutting instru- 
ments. [See Sulphuric Ether.) 
1289. Sulphuret of Gold is procured by passing sulphuretted hydro- 
gen through an aqueous solution of muriate of gold. Itis a black sub- 
stance consisting probably of 103.4 gold + 32 sulphur.—Oberkamff, 
Annales de Chimie, Tom. lxxx. 
1290. Sulphate of Gold is formed by digesting the oxide in dilute sul- 
phuric acid, but the salt has not been examined. 
1291. Phosphuret of Gold is obtained by heating gold leaf with phos- 
phorus, in a tube deprived of air. It is a grey substance of a metal- 
lic lustre, and consists probably of 103.4 gold + 12 phosphorus. 
1292. Alloys of Gold.—A very curious detail of an extended and 
accurate series of experiments upon the alloys of gold has been pub- 
lished in the Philosophical Transactions for 1803, by Mr. Hatchett: his 
experiments were generally made with 11 parts of gold and 1 of alloy ; 
or 38 grains of alloy to the ounce of gold. 
1293. The alloys of gold with potassium, sodium, and manganese, 
have not been examined. With iron the alloy is malleable and ductile, 
and harder than gold, its colour dull white, and its specific gravity 
16.885. The metals expand by union, so that supposing their bulk 
before combination to have been 1000, after combination it is 1014.7. 
1294. With zinc the compound is brittle and brass-coloured. Spe- 
cific gravity 16.937. The metals contract a little in uniting, the origin- 
al bulk being 1000, that of the alloy is 997. The brittleness conti- 
nued when the zinc was reduced to +- of the alloy. The fumes of 
zinc in a furnace containing fused gold, make it brittle. 
1295. Tin formed a whitish alloy, brittle when thick, but flexible 
in thin pieces. Specific gravity 17.307. Bulk before fusion 1000 ; 
after fusion 981. So that there is considerable contraction. The old 
chemists called tin diabolus metalloruin, from its property of rendering 
gold brittle, but Mr. Bingley’s experiments quoted by Mr. Hatchett, 
show that +• of tin does not render gold brittle. 
1296. The alloy of lead is very brittle when that metal only consti- 
tutes T+(j- of the alloy ; even the fumes of lead destroy the ductility 
of gold. The specific gravity is 18.080; and 1000 parts become 
1005. A very remarkable fact in respect to this alloy is, that its spe- 
cific gravity diminishes, to a certain extent, as the proportion of lead 
diminishes, and is at its maximum when the lead amounts only to ++h 
part, the quantity of gold remaining the same, and the deficiency being ALLOYS OF GOLD. 
made up with copper. The following Table, drawn up by Mr. Hatch- 
ett, exhibits this remarkable fact: 
METALS. 
Grains. j 
Sj). Gravity 
of Alloy. 
Bulk before i 
Union. | 
Bulk after | 
Union. 1 
Expansion. 
G old 
442 
18.080 
1000 
1005 
5 
Lead 
38 
Gold 
442 
Copper .... 
19 
17.765 
1000 
1005 
6 
Lead 
19 
Gold 
442 
Copper .... 
30 
17.312 
1000 
1022 
22 
Lead 
8 
Gold 
442 
Copper .... 
34 
17.032 
1000 
1035 
35 
Lead 
4 
Gold 
442 
Copper .... 
37.5 
16.627 
1000 
1057 
57 
Lead 
0.5 
/ 
Gold 
j 442 
Copper .... 
37.75 
17.039 
1000 
1031 
31 
Lead 
0.75 
1297. The alloy with nickel was of a brass colour and brittle. The 
specific gravity of the gold being 19.172, and of the nickel 7.8, that of 
the alloy was 17.068. An expansion had taken place, 1000 parts be- 
fore fusion having become 1007. 
1298. With cobalt the alloy was very brittle. Specific gravity 
17.112. 1000 parts became 1001 after fusion. 
1299. With bismuth the alloy was of a brass colour, very brittle, 
and of a specific gravity = 18.038. 1000 parts became 988 after fu- 
sion, so that the condensation was considerable. When the bismuth 
amounted only to part, the alloy was still brittle, though the 
colour was nearly that of gold. 
1300. With copper (standard gold) the alloy is perfectly ductile and 
malleable, but harder than pure gold, and resists wear better than any 
other alloy except that with silver. Its specific gravity is 17.157. 
Gold coin is an alloy of eleven parts of gold and one of copper ; of 
this alloy, twenty troy pounds are coined into 934 sovei'eigns and one 
half sovereign ; one pound formerly was coined into 44£ guineas ; it 
now produces 46f £ sovereigns. 
1301. Arsenic and antimony, when alloyed in very small proportions 
with gold, destroy its colour and render it quite brittle. 
1302. The analysis of most of the alloys of gold is performed by 
cupellation. The triple alloy of gold, silver, and copper, may be an- 
alyzed by digesting it in nitric acid, which takes up the silver and cop- 
per, and leaves the gold in the form of a black powder, which may be 
fused into a button, and Aveighed. The silver may be thrown down in 
the state of chloride by solution of common salt, and the copper preci- 
pitated by iron. 
1303. The assay of gold is more complicated than that of silver, in 
consequence of the high attraction which it has for copper, and which COMBINATIONS OF PLATINUM. 
307 
prevents its complete separation by mere cupellation. An alloy, there- 
fore, of copper with gold, is combined with a certain quantity of sil- 
ver, previous to cupellation ; this is then cupelled with lead in the 
usual way, and the silver is afterwards separated by the action of 
nitric acid. 
1304. The real quantity of gold or silver taken for an assay is very 
small; from 18 to 36 grains, for instance, for silver, and from 6 to 12 for 
gold ; whatever the quantity may be it is called the assay pound. The 
silver assay pound is divided into 12 ounces, and each ounce into 20 
penny-weights. The gold assay pound is subdivided into 24 carats, 
and each carat into 4 assay grains.—Aikin’s Dictionary. Art. Assay. 
1305. Mercury and gold combine with great ease, and produce a 
white amalgam much used in gilding. For this purpose the amalgam 
is applied to the surface of the silver; the mercury is then driven oft’ 
by heat, and the gold remains adhering to the silver, and is burnished. 
This process is called water gilding. 
In gilding porcelain gold powder is generally employed, obtained by 
the decomposition of the muriate ; it is applied with a pencil, and bur- 
nished after it has been exposed to the heat of the porcelain furnace. 
Many curious tacts relating to the properties of gold, and its uses in 
the arts, will be found in Dr. Lewis’s Philosophical Commerce of the 
Arts. 
Section XXXVI. Platinum. 
1306. This metal is found in small grains in South America, confin- j 
ed to alluvial strata in New Granada. These grains, besides platinum, 
contain generally gold, iron, lead, palladium, rhodium, iridium, and os- 
mium. 
The pure metal may be obtained by dissolving crude platinum in ni- 
tro-muriatic acid, and precipitating by a solution of muriate of ammo-1 
nia. This first precipitate is heated, dissolved in nitro-muriatic acid, 
and again precipitated as before. The second precipitate is heated 
white hot, and pure platinum remains. It is a white metal, extremely 
difficult of fusion, and unaltered by the joint action of heat and air. 
Its specific gravity is 21.5. It is very ductile, malleable, and tena- 
cious. 
1307. Platinum and Oxygen.—When nitrate of mercury is added to 
a dilute solution of muriate of platinum, a powder falls, which, when 
carefully heated, gives oft' calomel, and leaves a black oxide of plati- 
num, composed, according to Mr. Cooper, of 100 platinum, -f* 4.5 ox- 
ygen.—Journal of Science and the Arts, Vol. iii. 
Berzelius obtained an oxide of platinum by decomposing the mu- 
riate by sulphuric acid, and adding excess of potassa to the sulphate ; 
a yellowish brown powder was obtained, which became nearly black 
on being dried, and consisted of 100 platinum + 16.4 oxygen. (Thom- 
son, Vol. i., p. 501.) ; but, according to Mr. Davy, the oxide, which 
is contained in the salts of platinum, consists of platinum 100, oxygen 
11.8. 
Hi,story. 
Mode of ob- 
taining. ALLOYS OF PLATINUM, 
1308. Chloride of Platinum is obtained by evaporating the muriate 
and exposing it nearly to a red heat. Its colour is brown, and it is 
scarcely soluble in water. It gives off chlorine by a red heat. Ac- 
cording to Mr. Edmund Davy, to whom we are principally indebted for 
our knowledge of the combinations of platinum, [Phil. Mag. Vol. xl.) 
it consists of 100 platinum -f- 37.9 chlorine. 
1309. Nitro-muriatic acid is the readiest solvent of platinum. The 
solution affords crystals which are very deliquescent and acrid ; they 
are a muriate of platinum. The solution of this muriate is distinguish- 
ed from all other metallic solutions by affording a precipitate upon the 
addition of muriate of ammonia, which is an ammonio-muriate of plati- 
num. Ferroeyanate of potassa affords no precipitate. The addition 
of potassa occasions a precipitate of a triple compound of the alcali and 
muriate. Sulphuretted hydrogen occasions a black precipitate. Ether 
separates the oxide of platinum in the same way as that of gold. Mu- 
riate of tin occasions a very characteristic red precipitate in very dilute 
solution of platinum. 
1310. There are, according to Mr. E. Davy, three sulphurets of pla- 
tinum. The first, formed by heating the finely-divided metal with sul- 
phur ; the second, by precipitating nitro-muriate of platinum by sulphu- 
retted hydrogen; and the third, by heating 3 parts of the ammonio- 
muriate with 2 of sulphur. 
1311. According to the same authority there are two phosphurets. 
The first, obtained by heating phosphorus with the metal ; the second, 
by heating phosphorus with the ammonio-muriate of platinum. 
1312. The salts of platinum have been but little examined. Proust 
and Davy have described a sulphate, obtained by acidifying the sul- 
phur in the sulphuret by means of nitric acid. It is of a brown colour, 
and very soluble ; and with soda, potassa, and ammonia, it forms triple 
salts. 
Mr. E. Davy found that the precipitate by a slight excess of ammo- 
nia, when boiled in potassa, washed and dried, was a fulminating plati- 
num; it explodes at about 420°, with a very loud report, and appears 
to be a compound of oxide of platinum, ammonia, and water.—Phil. 
Trans., 1817. 
1313. A very singular compound of platinum is described by Mr. E. 
Davy, in the Philosophical Transactions (1820, p. 108), obtained by 
mixing equal volumes of strong aqueous solution of the sulphate and 
of alcohol. The colour of the sulphate slow ly disappears, and in some 
days a black substance subsides, which is waashed and dried. It is also 
formed by boiling the sulphate and alcohol together for a few minutes. 
This substance is permanent in the air and insoluble in water. It de- 
tonates feebly when heated, and is not affected by chlorine, nor by 
nitric, sulphuric, and phosphoric acids ; but it is slowly soluble in mu- 
riatic acid. Put into liquid ammonia it acquires fulminating properties, 
and plunged into the gas it becomes red hot: the same phenomenon is 
exhibited by exposing it to the vapour of alcohol, or by placing it upon 
a piece of paper moistened with that fluid : in these cases the platinum 
is reduced with the evolution of heat, and the ignition seems to depend 
upon the slow combustion of the vapour of the alcohol, as has been 
elsewhere shown. (191.) From Mr. Davy’s analysis of this compound, 
it appears to contain 96.25 platinum, 0.12 oxygen, 0.0106 carbon 3.6194 
nitric acid and water; the acid being derived from the mode of prepar- 
ing the sulphate. (1312.) SILICIUM. 
1314. Experiments upon the composition of the various combina- 
tions of platinum are so entirely at variance with theory, that in the 
present state of our knowledge it is scarcely possible to deduce the 
number for platinum. 
If the black oxide, described by Mr. Cooper, be considered as a 
protoxide, the number 177.7 will represent platinum, and the chloride 
(1308) will contain 1 proportional of platinum and 2 of chlorine. But 
the peroxide, the phosphurets, and the sulphurets, will not accord with 
this number. 
1315. The alloys of platinum have not been applied to any useful 
purposes. By combining 7 parts of platinum with 16 of copper and 
1 of zinc, Mr. Cooper obtained a mixture much resembling gold.—• 
Journal of Science and Arts, Vol. iii., p. 119. 
1316. Zinc, bismuth, tin, and arsenic, readily combine with platinum, 
and form fusible alloys. It also unites, though less readily, with cop- 
per, lead, and iron. It combines with gold, and unless there be great 
excess of the latter, the colour of the alloy resembles platinum. 
1317. If a small piece of tin, zinc, or antimony, be rolled up in pla- 
tinum leaf, and exposed to the jet of a blow-pipe, the two metals com- 
bine with such energy, when nearly white hot, as to produce a kind of 
explosion. Iron and steel also remarkably increase the fusibility of 
platinum. 
1318. The alloys of steel and platinum have been examined by Sto- 
dart and Faraday. They combine in all proportions, but from 1 to 3 
per cent, of platinum appears best adapted for cutting instruments. 
Equal weights of the two metals produce a tine hard and brilliant alloy 
of a specific gravity of 9.862 ; it appears well adapted for mirrors, for 
it takes a fine polish and does not tarnish. An alloy of 90 platinum and 
20 steel has a specific gravity of 15.88. 
1319. Platinum has the property of being united by welding, either 
one piece to another, or with iron, or steel. Wires of steel and pla- 
tinum, when welded and polished, exhibit a curious and beautiful sur- 
face, especially when the steel parts are slightly acted upon by dilute 
acid. This welding property of platinum may be usefully applied in 
the arts ; rings may be joined so as to form a chain, the durability of 
wrhich must add to its value ; and with a view to economy, platinum 
maybe joined to iron or steel for many uses in the laboratory of the 
chemist. 
Section XXXVII. Silicium. 
1320. It lias been assumed that the earth silica consists of a me- 
tallic basis, united with oxygen, and that it contains 50per cent, of each 
of its components ; so that, if the earth be considered a deutoxide, it 
will consist of 
16 silicium 
16 oxygen 
32 
(1 proportional) 
(2 proportionals) GLASS. 
This estimate of the composition of silica is deduced from the 
quantity of potassium which is required for its decomposition, but the 
subject requires farther elucidation. 
1321. Oxide of Silicium, Silica, or Siliceous Earth, is a very abun- 
dant natural product. It exists pure in rock-crystal, and nearly pure 
in flint. It may be obtained by heating colourless rock-crystal to red- 
ness, quenching it in water, and reducing it to a fine powder; in this 
state it is silica almost perfectly pux*e. Fuse 1 part of this powder 
with three of potassa in a silver crucible. Dissolve the mass formed, 
in water, add slight excess of muriatic acid, and evaporate to dryness. 
Wash the dry mass in boiling distilled water upon a filter, and the white 
substance which remains is silica. This is the usual process, but the 
earth obtained by simply reducing the colourless rock-crystal to pow- 
der, is more pure ; for I have never been able to separate the last por- 
tions of alcali from silica precipitated from potassa. 
1322. Silica is white ; its specific gravity 2.66. It fuses at a very 
high temperature. In its ordinary state it is insoluble in water ; but 
it dissolves in very minute portions in that fluid, when recently pre- 
cipitated in the form of gelatinous hydrate ; and in the same state it 
dissolves sparingly in the acids. It readily unites with the fixed alcalis, 
and forms glass; or, if the alcali be in excess, a liquid solution of the 
earth may be obtained (liquor silicum), from which it is precipitated 
in the state of a gelatinous hydrate by acids. This alcaline solution, 
after having been kept for several years, has formed small crystals of 
silica. I have seen in it a deposit much like calcedony, and as hard. 
1323. Glass is essentially a compound of silica with fixed alcali, a 
variety of other substances being occasionally added for particular 
purposes, among which oxide of lead is perhaps the most important. 
The silica used in the manufacture of glass is of various degrees of 
purity; fine white sand is generally in this country ; flints, 
and the white quartz pebbles, abundant in some rivers, are also occa- 
sionally used. The alcali is either potassa or soda ; purified pearlash 
being preferred for fine glass; while less pure substances, such as 
wood-ash, barilla, and kelp, are used for common glass, where the im- 
purities contained in those alcalis are of no importance. The alcali 
is always in the state of carbonate, but it loses its carbonic acid during 
combination with the silica; the quantity employed is about half the 
weight of the silica, but there is some loss during the process, by eva- 
poration. 
A glass composed solely of silica and alcali requires a very high tem- 
perature for its perfect fusion, and is very difficult to work, so that va- 
rious substances are added, with the intention of forming a more fusible, 
colourless, dense, and transparent compound ; oxide of lead, in the 
form of litharge or minium, is very efficacious in this respect ; it in- 
creases the fusibility of the compound, gives it greater tenaciousness 
when red hot, increases its refractive power, and enables it to bear 
sudden changes of temperature. It is a copious ingredient in the Lon- 
don Jlint glass, celebrated for its brilliancy when cut, and used for most 
optical purposes. But lead, though it confers these advantages, is pro- 
ductive of some evil; it renders the glass so soft as easily to scratch, 
and so fusible that it softens at a dull red heat, a quality which, though 
sometimes desirable, is often disadvantageous in its chemical applica- 
tions. It is also very difficult to obtain a mass of glass containing lead, (HASS. 
of equal density throughout; it is generally wavy, a defect especially 
felt in selecting the object-glasses of telescopes. 
Boracic acid and borax form an admirable flux for glass-making, but 
the expense of those materials confines them almost entirely to the 
manufacture of artificial gems. 
Black oxide of manganese has long been used in glass-making ; it was 
formerly called glassr soap, a term implying its power of cleansing cer- 
tain impurities, and especially the green tinge which is apt to arise from 
impure alcali; but if it be added at all in excess, it communicates a pur- 
ple tinge, more or less intense according to its quantity. This purple 
hue is destroyed by charcoal, or by thrusting a billet of wood into the 
glass-pot, which causes a slight effervescence, and the colour disappears. 
There can be little doubt that the carbon acts by deoxidizing the man- 
ganese, for if a little nitre be added, the purple colour returns. Lime 
in very small quantities (8 or 10 parts of chalk to 100 of silica), is 
sometimes added to glass ; it acts as a flux, but it endangers the trans- 
parency of the compound. 
White arsenic is also used as a very cheap and powerful flux ; and 
nitre, in small quantities, is employed to destroy any impurities arising 
from carbonaceous matter. 
1324. The materials for the manufacture of glass are submitted to 
an operation called fritting, before they are transferred to the regular 
glass-furnace. It consists in exposing them to a dull red heat, by which 
moisture and carbonic acid are expelled, and a slight degree of chemical 
action induced ; this also prevents the excessive swelling up of the ma- 
terials in the glass-pots, and renders the process of vitrification more 
certain and expeditious. 
The glass-pots are placed round a dome-shaped furnace, built upon 
arches, and open beneath for the free admission of air; there are ge- 
nerally six in each furnace, and they are entirely enclosed except at an 
orifice on the side, opening into a small recess formed by the alternate 
projections of the masonry and the flues, in which recess the workmen 
stand. Coal is the fuel employed, and the furnace is so built that a ra- 
pid current of flame may be directed round each glass-pot, which af- 
terwards passes out with the smoke into the dome and chimney, heating 
a broad covered shelf in its passage, which is the annealing oven. 
In the construction of the furnace and pots the greatest care is re- 
quired ; especially in the latter, which have not only to resist long- 
continued heat, but also as far as possible, the action of ingredients 
which tend to accelerate their fusion or vitrification. They are usual- 
ly made entirely of a refractory clay, one portion being crude or un- 
burnt, and another calcined and powdered ; the latter being the re- 
mains of former furnaces when pulled down for repairs, 
The frit is introduced into the glass-pots through the side-opening 
above-mentioned, and being heated to bright redness, becomes of a 
pasty consistency, and at length perfectly fuses. A quantity of impuri- 
ties subside to the bottom of the pot, and partly rise to its surface. 
The scum, known under the name of sandiver, consists chiefly of sa- 
line substances, partly volatile at the high temperature of the furnace, 
which are removed from time to time, and sold to metal refiners as a 
powerful flux. The sandiver or glass gall being separated, the mate- 
rials gradually become clearer, abundance of air-bubbles are extricat- 
ed, and at length the glass appears uniform and complete ; the fire GLASS. 
round the individual pot is then damped till its contents acquire a con- 
sistency fit for working, the whole process requiring about 48 hours 
from the time the pots are filled. At the working heat, which is a full 
red, the glass has a very peculiar tenacious consistency, and as it ad- 
heres but feebly to polished metal, it is easily wrought and managed 
with iron tools. 
1325. All glass articles require to be carefully annealed, that is, 
suffered to cool very slowly, otherwise they are remarkably brittle and 
apt to crack, and even fly into many pieces upon the slighest touch of 
any hard substance, as is well shown in the small drops of green glass 
suddenly cooled by dropping it into water, and called Rupert's drops ; 
the instant their thin end is broken off, they crumble into a powder with 
a kind of explosion. This phenomenon, according to Mr. Aikin, 
“ depends upon some permament and strong inequality of pressure, 
lor when they are heated so red as to be soft, and merely let cool of 
themselves, the property of bursting is lost, and the specific gravity of 
the drop increased.” What are termed Bologna phials are also made 
of unannealed glass, and fly to pieces when a piece of flint or other 
hard and angular substance is dropped into them. 
1326. The exact composition of the different kinds of glass is 
scarcely known ; the following proportions of the materials are, how- 
ever, given in Messrs. Aikin’s Dictionary, to which the reader is refer- 
red for a very valuable article upon the subject of glass, and from 
which I have abridged the preceding account. 
Flint Glass. Specific gravity about 3.2, 
120 parts of fine clear white sand 
40 purified pearlash 
35 litharge or minium 
13 nitre 
A small quantity of black oxide of manganese. 
Crown Glass or best window glass. 
200 parts of soda 
300 fine sand 
33 lime 
250 ground fragments Of glass. 
Green Bottle Glass. 
100 parts of sand 
30 
coarse kelp 
160 
lixiviated earth of wood-ashes 
30 
fresh wood-ash 
80 
— brick clay 
100 
fragments of glass. 
Plate Glass, invented by Abraham Thevart in 1688. was first manu- 
factured in Paris. It may be composed of 
300 
lbs. 
fine sftnd 
200 
lbs. 
soda 
30 
lbs. 
lirne 
32 
oz. 
manganese 
3 
oz. 
cobalt azure 
300 
lbs. 
fragments of good glass white enamel. 
313 
These materials are brought into perfect fusion, and poured upon a 
hot copper-plate, the mass is then rolled out, annealed, and afterwards 
polished by grinding with sand, emery, and colcothar. The difficulty 
of producing a perfect plate without specks, bubbles, or waves, may 
easily be conceived, and this, with the risk of breakage, renders a 
large plate extremely expensive. 
1327. The art of colouring glass, and of making artificial gems, is 
of an old date, and effected by metallic oxides. Thepasfe for artificial 
gems generally contains borax, and should be kept in fusion till per- 
fectly clear. The following proportions are recommended by M. Pou- 
ault-Wieland.—Annales de Chim. et Phys., Tom. xix., 57. 
Grains. 
Powdered rock-crystal. . . 
. . 4056 
Red lead 
Pure potassa 
. . 2154 
Borax 
Arsenic 
M. J*an§on gives the following as ingredients for a good paste ;«—» 
Grains. 
Litharge 
White sand 
. . 75 
White tartar or pot-ash . . . 
10 
1328. The metals employed as colouring materials are: I. Gold. 
The purple of Caaaiue imparts a fine ruby tint 2. Silver. Oxide or 
phosphate of silver gives a yellow colour. 3. Iron. The oxides of 
iron produce green, yellow, and brown, depending upon the state of 
oxidizement and quantity. 4. Copper. The oxides of copper give a 
rich green ; they also produce a red when mixed with a small propor- 
tion of tartar, which tends partially to reduce the oxide. 5. Antimony 
imparts a rich yellow. 6 Manganese. The black oxide of this me- 
tal, in large quantities, forms a black glass ; in smaller quantities, various 
shades of purple. 7. Cobalt, in the state of oxide, gives beautiful 
blues of various shades ; and with the yellow of antimony or lead it 
produces green. 8 Chrome produces fine greens and reds, depend- 
ing upon its state of oxydizement. 
The following are the best authorities upon the subject of coloured 
glasses and artificial gems :—Neri, Art de la Verrerie. Kunckel. 
Fontanieu, Encyclopedic Meihodique. Annales de Chim. et Phys., xiv.? 
57. Aikin’s Dictionary, Art. Glass. 
1329. White Enamel is merely glass, rendered more or less milky or 
opaque by the addition of oxide of tin ; it forms the basis of the colour- 
ed enamels, which are tinged with the metallic oxides. 
1330. The only acid body which acts energetically upon silica is the 
hydrofluoric acid (618.) The result of this action is a gaseous com- 
pound, which has been called silicated fluoric acid, orfluo-silicic acid ; 
it is probably a compound of silicium and fluorine. 
1331. To obtain this gaseous compound, three parts of fluor spar, 
and one of silica finely powdered, are mixed in a retort with an equal 
weight of sulphuric acid; a gentle heat is applied* and the gas evoly- 
■ed is to be collected over mercury. SILICEOUS MINERALS- 
1332. Sihcated fluoric acid is a colourless gas ; its odour is acrid, 
much resembling muriatic acid ; its taste very sour ; its specific gravi- 
ty 3.574 compared with air; 100 cubic inches weigh 110.78 grains, 
so that its specific gravity to hydrogen is 49.2. It extinguishes burning 
bodies. It produces white fumes when in contact with damp air ; and 
when exposed to water, two compounds of silica with fluoric acid are 
formed ; the one acid, and dissolved in the water ; the other contain- 
ing excess of silica, and insoluble. The dry compound contains 62 per 
cent, of silica ; the aqueous solution only retains 55 per cent. Water 
dissolves 260 times its bulk of this gas. 
1333. When one volume of silicated fluoric acid is mixed with two of 
ammonia, a total condensation ensues, and a dry silico-fluate of ammo- 
nia results. 
1334. Potassium when heated in this gas, burns and produces a 
brown compound, which when dissolved in water, affords hydrofluate 
of potassa. 
1335. It appears from the experiments of Mr. J. F. Daniell, that 
silicium exists in some of the varieties of cast iron : (Journal of Science 
and Arts, Vol. ii.), and an alloy containing it has been formed by M. M. 
Stromeyer and Berzelius, (Gilbert’s Annalen, xxxviii.) by exposing 
a mixture of pure iron, silica, and charcoal, to an intense heat. 
1336. The fossils consisting of silica, pure, or nearly so, are princi- 
pally the following : 
i. Rock-crystal, or Quartz, which may be considered as pure silica. 
It crystallizes in the form of a six-sided prism, ended by six-sided pyra- 
mids ; some varieties are perfectly transparent and colourless ; others 
white and more or less opaque. Its specific gravity is 2.6. It is so 
hard as to give sparks when struck with steel, and is nearly infusible. 
The primitive crystal, which is very rare, is an obtuse rhomboid, the 
angles of which are 94° 24', and 85° 36'. The finest specimens are 
brought from Madagascar and the Alps. The perfectly transparent 
crystals found near Bristol, and in Cornwall, are sometimes called Bris- 
tol and Cornish diamonds. The fine crystals are cut into ornaments, 
and sometimes used as a substitute for glass in spectacles ; they are 
then termed pebbles, and do not so readily become scratched as glass. 
Brown and yellow crystals of Quartz are found in great beauty in the 
mountain of Cairn Gorm in Scotland, and are much admired for seal 
stones, &rc.: they are sometimes improperly termed topazes. 
Purple quartz, or amethyst, is tinged with a little iron and manganese. 
Rose quartz derives its colour from manganese. Prase, or green quartz, 
contains actinolite ; and chrysoprase is tinged of a delicate apple-green 
by oxide of nickel. Avanturine is a beautiful variety of quartz, of a 
rich brown colour, which, from a peculiarity of texture, appears filled 
with bright spangles ; the finest specimens are from Spain ; it is often 
imitated. Small crystals of quartz, tinged with iron, are found in Spain, 
and have been termed hyacinths of ComposUlla. 
ii. Flint, Chalcedony, Carnelian, Onyx, Sardonyx, and Bloodstone or 
Heliotrope, and the numerous varieties of Agates are principally com- 
posed of quartz, with various tinging materials. 
iii. Opal is among the most beautiful productions of the mineral 
world ; it is a compound of about 90 silica and 10 water, and is distin- 
guished by its very brilliant play of colours. The finest specimens 
come exclusively from Hungary. There is a variety of opal called ALW>I. 
Ilydrophane, which is white and opaque till immersed in water ; it then 
resembles the former. 
Common Opal is usually of a dirty white, and does not exhibit the 
colours of the noble opal; it contains silica and water, with a little ox- 
ide of iron, and is not of unfrequent occurrence. The substance called 
menilite from Menil Montant, near Paris, is nearly allied to common 
opal. It is found in irregular masses in a bed of clay. 
iv. Pitchstone, so- called from its resinous appearance, contains 73 
per cent, of silica. Obsidian, a volcanic product, contains 78 per cent. 
of silica, and much resembles glass in appearance ; and the different 
kinds of pumice are nearly of similar composition. 
Section XXXVIII. Alumium, 
1337. The earth alumina constitutes some of the hardest gems, such 
as the sapphire and ruby ; and combined with water, it gives a pecu- 
liar softness and plasticity to some earthy compounds, such as the dif- 
ferent kinds of clay. It is analogically considered as a metallic oxide. 
1338. There can I think be little doubt of the existence of silicium 
md alumium, as well as of calcium, and probably magnesium, in some 
of the varieties of cast-iron and steel. By fusing highly carburetted 
Bteel with alumina, a peculiar alloy results, which is white, granular, 
and brittle, and which yields on analysis 6.4 per cent, alumina. On 
fusing 67 parts of this alloy with 500 of steel, a compound is obtained, 
which possesses all the charac.tpre pf the bact Bombaywantz (761), and 
tike it, when itc anrfooo is polished and washed over with dilute sulphu- 
ric acid, exhibits the striated appearance called damask, for which the 
celebrated sabres of Damascus are remarkable, and which renders it 
probable that they also are made of wootz. (Quarterly Journal of Sci- 
ence and Arts, ix.). Many of the varieties of cast-iron afford lime and 
silica when dissolved in acids, and it is highly probable that those sub- 
stances, as well as the alumina in the wootz, exist combined with the 
iron in their deoxidized or metallic state. 
1339. To obtain pure alumina, we add carbonate of ammonia to a 
solution of alum, wash, and ignite the precipitate ; it is a tasteless 
white substance, forming a eohesive mass with water, and retaining 
water even at a red heat. Its specific gravity is 2. It is soluble in 
soda and potassa, and forms compounds with baryta, strontia, lime, and 
silica. It is an essential ingredient in pottery and porcelain. 
1340. One of its saline combinations is of important use in the arts, 
namely, alum; a triple sulphate of alumina and potassa. This salt is 
usually prepared by roasting and lixiviating certain clays containing 
pyrites ; to the leys, a certain quantity of potassa is added, and the 
triple salt is obtained by crystallization*. 
Alum has a sweetish astringent taste. It dissolves in 5 parts of water 
at 60°, and the solution reddens blues. It furnishes octoedral crystals. 
* Sulphate of alumina will not crystallize; but if a solution of sulphate of potassa be add- 
ed to solution of sulphate of alumina, small octoedral crystals of alum are precipitated. i*YROPORUS. 
When heated, it loses water of crystallization and a part of its acid, 
and becomes a white spongy mass. In its crystalline form it consists, 
according to some recent experiments made by Mr. R. Phillips, of 
Sulphate of alumina . . . . 
. . 123.00 
Bi-sulphate of potassa . . . 
. . 119.32 
Water 
429.32 
Mr. Phillips adopts the number 24 as the representative of alumina, 
and considers alum as a compound of 2 proportionals of sulphate of 
alumina, 1 of bi-sulphate of potassa, and 22 of water. These propor- 
tions, therefore, would be 
Bi-sulphate of potassa , 
— 128 
Sulphate of alumina . 
. 61.5 X 2 = 123 
Water 
.9. X 22 — 198 
449 
1341. When alum is exposed to an intense heat, it loses water, and 
a portion of acid; but the whole of the acid cannot be expelled. It 
becomes light and spongy; and in this state is called in the Pharmaco- 
peia, Alumen ustum, or exsiccatum. If alum contain excess of potassa 
it forms cubic crystals, and is known under the name of cubic alum. 
Some varieties of alum contain ammonia. 
1342. When alum is ignited with charcoal, a spontaneously inflam- 
mable compound results, which has long been known under the name 
of Homberg's pyrophorus. The potassa appears to be decomposed in 
this process, along wiin me aciu or me nium, and pyrophorus is proba- 
bly a compound of sulphur, charcoal, and potassium, witn alumina. 
Pyrophorus is most successfully prepared by the following process. 
Mix equal parts of honey, or of brown sugar and powdered alum, in an 
iron ladle, melt the mixture over a fire, and keep it stirred till dry: 
reduce the dry mass to powder, and introduce it into a common phial 
coated with clay, and placed in a crucible of sand. Give the whole a 
red heat, and when a blue flame appears at the neck of the phial, allow 
it to burn about five minutes, then remove it from the fire ; stop the 
phial, and allow it to cool, taking care that air cannot enter it. 
1343. Alum is of extensive use in the arts, more especially in dye- 
ing and calico-printing, in consequence of the attraction which alumina 
has for coluring matter. 
1344. A triple sulphate of alumina and soda is described in the Quar- 
terly Journal of Science and Arts, (viii. 386.) in the form of irregular 
efflorescent octoedra : it appears to contain 
2 proportionals sulphate of alumina 61.5 X 2 = 123 
1 bi-sulphate of soda = 112 
28 water 9. X28 = 252 
487 
1345. The remaining salts of alumina with the exception of the SItICO-ALUMINOUS MINERALS. 
acetate, which remains to be described, are of little importance ; what 
is known respecting them is fully detailed by Dr. Thomson.—System, 
Vol. ii., p. 510. 
1346. Under the term corundum certain mineral substances have 
been included, composed of alumina, nearly pure. 
i. Perfect corundum occurs crystallized in six-sided prisms, transpa- 
rent and colourless. Its specific gravity is about 4. When blue, it 
constitutes the sapphire; when red, the ruby; when yellow, the ori- 
ental topaz, or chrysolite. These gems are principally found in alluvial 
deposits. They are mostly procured from Ceylon and Pegu ; they 
have also been found in France and in Bohemia, 
ii. Imperfect corundum, or adamantine spar and emery, are nearly an- 
alogous in composition to the former • thp.y contain from 3 to 5 per 
cent, of silica and 1 to 2 of oxide of iron. 
iii. Spinelle or balass ruby, is found in octoedral crystals, of a red co- 
lour. It is composed of 74.5 alumina, 16.5 silica, 3.25 magnesia, 1.5 
oxide of iron, and traces of lime and oxide of chrome. The ceylanite 
or pleonaste, is a variety of Spinelle. A variety, containing oxide of 
zinc, is called zinc spinelle, or automalite. 
iv. The mineral, called Wavellite, or hydrargillite, is a compound of 
alumina, phosphoric acid, and water. It is found in Devonshire, in 
small radiated nodules upon clay-slate. According to Berzelius, {An- 
nales de Chitn. et Phys., Tom. xii.) 100 parts alford 
Alumina 
35.35 
Phosphoric acid 
33.40 
Fluoric acid 
2.06 
Lime 
0.50 
Oxides of iron and manganese 
1.25 
Water 
26.80 
99.36 
V. The occidental topaz, found chiefly in Saxony, Siberia, Brazil, and 
Scotland, consists of alumina, silica, and fluoric acid. The schorlous 
beryl or pycnite, and the pyrophysalite, are nearly of the same compo- 
sition. 
vi. Cryolite, a rare substance hitherto only found in Greenland, con - 
sists of alumina, soda, and fluoric acid. It is white, amorphous, and 
translucent. 
vii. A mineral, called native alumina, is found upon the Sussex coast, 
near New-haven. It is white and friable, and occurs massive and in- 
crusting. It contains alumina and sulphate of lime. 
1347. A very numerous and important class of minerals consists of a 
combination of silica with alumina, in various proportions, and with 
the occasional addition of the fixed alcalis or alcaline earths, and a few' 
of the other metallic oxides : the principal of these, which are not 
elsewhere mentioned, are the following : 
i. Zeolite.—Of this mineral there are several varieties. The prin- 
cipal are the radiated or mesotype ; the nacreous or stilbite; the efflo- 
rescent or laumonite ; and the cubic or analcime. These minerals fuse 
and intumesce before the blow-pipe, and mostly form gelatinous solu- SILICIO-ALUMINOUS MINERALS. 
tions in the acids. The following is Vaucpielin’s analysis of a radiated 
or acicular zeolite : 
Silica 
Alumina 
Lime 
9.46 
Water . 
ii. Apophyllite and Chabasite are nearly of the same composition ; ex- 
cept that the latter contains about 9 per cent, of potassa and soda. 
iii. Garnet occurs massive, but generally crystallized in dodecaedra. 
garnet is red and transparent; the common garnet, red, 
brown, or green. Accordingto Vaxnjuelin, the precious garnet consists 
of 
Silica 
Alumina 
Oxide of iron 
Lime . . 
The cinnamon stone of Ceylon is nearly of similar composition. 
iv. Melanite, or black garnet, contains, upon the same authority, 
Silica • 
Alumina • 
Lime 
Oxides of iron and manganese . . . 
. . 25 
v. Leucite, or white volcanic garnet, contains, according to Klaproth, 
Silica . . . . 
Alumina . . . 
. . . . 24 
Potassa . . . 
. . . . 21 
vi. Vesuvian, or idocrase, is brown or yellow red, and is found crys- 
tallized in the masses of rock ejected by Vesuvius and Etna. It has 
also been found in the Alps and in Siberia. The Neapolitan lapidaries 
call it chrysolite of Vesuvius. In composition it differs little from me- 
lanite. 
vii. Staurotide, or grenalite, crystallizes in four and six-sided prisms 
often crossing each other. It consists of 
Silica 
33 
Alumina 
44 
Lime 
3.8 
Oxides of iron and manganese . 
14 
viii. Sodalitc and natrolite are minerals containing a considerable 
portion of soda. The former has been analyzed by Dr. Thomson. 
It has hitherto only been found in Greenland and on Vesuvius. Its 
colour is light green, and it occurs massive and crystallized in rhomboi- 
dal dodecaedra. It consists of '38.42 
silica 
27.48 
alumina 
23.50 
soda 
2.70 
lime 
3.00 
muriatic acid 
1.00 
oxide of iron 
2.10 
volatile matter. 
SILICO-ALVMINOUS MINERALS, 
ix. Prehnite is of a greenish colour, and radiated fracture. It oc- 
curs massive and crystallized in prisms. A lamellar variety has been 
called koupholite. It is found near the Cape of Good Hope, and in 
France and Scotland. 
x. Spodumene, or triphane, is a mineral already alluded to in the 
section on Lithium. It is nearly allied to feldspar, and consists of 
65 
silica 
25 
alumina 
8 
lithia 
2 
oxide of iron. 
100 
xi. Scapolite, and Elaolite, or Fettstein, are minerals hitherto found 
only in Norway : they contain about 45 per cent, of silica, and 33 of 
alumina. The scapolite contains about 18 per cent, of lime ; the ela- 
olite, the same proportion of potassa and soda. 
xii. Nephritic stone, or jade, which is found in the Alps, and in China 
and India, contains, according to Saussure, 
53.7 silica 
12.7 lime 
7 ozide of iron and manganese 
10.7 soda 
8.5 potassa 
7.4 water and loss. 
100.0 
The Chinese cut this substance into figures, and it is sometimes used 
tor the handles of cutting-instruments. In New Zealand and other 
islands of the Pacific Ocean it is used for cutting instruments, in conse- 
quence of its hardness and toughness. Hence it has been called axe 
stone. 
xiii. Schorl and Tourmalin consist principally of silica, alumina, 
and oxide of iron. They occur in prismatic crystals of a black colour. 
xiv. Thallite, epidote, or pistacite, is nearly allied in composition to 
schorl. It occurs in green prismatic crystals. 
xv. Axinite, or thumerstone, is found crystallized in flat oblique 
rhombs, of a brown, bluish, or grey tint, and transparent. It consists-; 
according to Vauquelin, of 
Silica 
Alumina 
Lime 
. . . 19 
Oxide of iron 
Qxide of manganese. , , , SILICO-MAGNESIANf MINERALS. 
xvi. Cyanite is of a blue and grey colour, translucent, and occur.?' 
massive and prismatic. It consists, according to Klaproth, of 
Alumina 
Silica 
Oxide of iron ..... 
xvii. Lepidolite occurs massive, and of a purplish colour and lamel- 
lar texture. According to Klaproth, it contains 
Silica 
54.5 
Alumina 
38.25 
Potassa 
4. 
Oxide of iron and manganese . 
0.75 
xviii. Actinolite is of a green colour, and generally occurs in aggre- 
gated masses of prismatic crystals. It contains 
Silica 
50. 
Lime 
9.7 
Magnesia 
19.2 
Alumina 
0.7 
Oxides of chrome and iron . . 
8. 
xix. Tremolite is nearly white, fibrous and semi-transparent. It 
contains 
Silica 
Lime 
Magnesia 
13 
Oxide of iron 
xx. Asbestos is a soft fibrous flexible mineral, of a white or greenish 
tint, composed of 
Silica 
Magnesia 
Lime 
Alumina 
Amianthus, mountain cork, and mountain wood, are varieties of asbes- 
tos. 
xxi. Lapis lazuli consists of 
Silica . 
Carbonate of lime 
Alumina 
Sulphate of lime 
. . 6.5 
Oxide of iron and water . . 
. . 5 
The blue colour is probably derived from some principle which has 
hitherto escaped analysis. It is prepared for painters under the name 
of ultra-marine. 
xxii. Harmotome, Staurolite, or Cross-stone, occurs in small quadrangu- 
lar prisms terminated by four rhombic planes, crossing each other. It 
is also found in single crystals. It is found at Andreasberg, in the CLAYS. 
321 
Hartz, and at Strontian, in Scotland. It consists, according to Kla- 
proth, of 
Silica 
. . . . 49 
Alumina 
. . . . 16 
Baryta 
. . . . 18 
Water 
. . . . 15 
xxiii. Augite is a mineral of a black or brownish green colour, found 
in volcanic products, and in some basalts. Sahlite and coccolite are va- 
rities of augite. It is composed of 
Silica 
52 
Lime 
13 
Oxide of iron and manganese 
16 
Magnesia 
10 
Alumina 
9 
xxiv. Datholite is a combination of 
Silica 
Lime 
Boracic acid .... 
. . . . 22 
Water 
It has only been found in Norway. 
1348. Under the term Clay is comprehended a variety of mixtures 
of silica and alumina, more or less pure, and characterized by a pecu- 
liar plasticity in their moist state. The following are the principal 
varieties. 
1. Porcelain Clay, derived principally from the decomposition of 
feldspar, and containing silica and alumina, sometimes with traces of 
oxide of iron; it is very difficult of fusion. 2. Marly Clay, which, 
with silica and alumina, contains a portion of carbonate of lime ; it is 
much used in making pale bricks, and as a manure, and when highly 
heated enters into fusion. 3. Pipe Clay, which is very plastic and te- 
nacious, and requires a higher temperature than the preceding for fu- 
sion ; when burned it is of a cream colour, and used for tobacco-pipes 
and white pottery 4. Potters’ Clay, is of a reddish or grey colour, 
and becomes red when heated ; it fuses at a bright red heat : mixed 
with sand it is manufactured into red bricks and tiles, and is also used 
for coarse pottery. 
1349. The better kind of pottery, called in this country Staffordshire 
ware, is made of an artificial mixture of alumina and silica ; the former 
obtained in the form of a fine clay, from Devonshire chiefly ; and the 
latter consisting of chert or flint, which is heated red-hot, quenched in 
water, and then reduced to powder. Each material, carefully pow- 
dered and sifted, is diffused through water, mixed by measure, and 
brought to a due consistency by evaporation : it is then highly plastic, 
and formed upon the potter’s wheel and lathe into various circular ves- 
sels, or moulded into other forms, which, after having been dried in a 
warm room, are enclosed in baked clay cases resembling bandboxes, 
and called seggars: these are ranged in the kiln so as nearly to fill it, 
teaving only space enough for the fuel; here the ware is kept red-hot crucibles. 
322 
for a considerable time, and thus brought to the state of biscuit. This 
is afterwards glazed, which is done “ by dipping the biscuit ware into 
a tub containing a mixture of about 60 parts of litharge, 10 of clay, and 
20 of ground flint, diffused in water to a creamy consistence, and when 
taken out enough adheres to the piece to give an uniform glazing when 
again heated. The pieces are then again packed up in the seggars, 
with small bits of pottery interposed between each, and fixed in a kiln 
as before. The glazing mixture fuses at a very moderate heat, and 
gives an uniform glossy coating, which finishes the process when it is 
intended for common white ware.”—Atkin's Dictionary. Art. Pot- 
tery. 
1350. The patterns upon ordinary porcelain, which are chiefly in 
blue, in consequence of the facility of applying cobalt, are generally 
printed off upon paper, which is applied to the plate or other article 
while in the state of biscuit, and adheres permanently to the surface 
when heat is properly applied. 
1351. The manufacture of porcelain is a most refined branch of art; 
the materials are selected with the greatest caution, it being necessary 
that the compound should remain perfectly white after exposure to 
heat: it is also required that it should endure a very high temperature 
without fusing, and at the same time acquire a semivitreous texture and 
a peculiar degree of translucency and toughness. These qualities are 
united in some of the oriental porcelain, or China, and in some of the 
old Dresden, but they are rarely found co-existent in that of modern 
European manufacture. Some of the Erench and English porcelain, 
especially that made at Sevres and at Worcester, is extremely white 
and duly translucent, but it is more apt to crack by sudden changes of 
temperature ; more brittle, and consequently requires to be formed into 
thicker and heavier vessels ; and more fusible than the finest porce- 
lains of Japan and China. 
1352. The colours employed in painting porcelain are the same me- 
tallic oxides enumerated for colouring glass, and in all the more deli- 
cate patterns they are laid bn with a camel-hair pencil, and generally 
previously mixed with a little oil of turpentine. Where several co- 
lours are used, they often require various temperatures for their per- 
fection, in which case those that bear the highest heat are first applied, 
and subsequently those which are brought out at lower temperatures. 
This art of painting on porcelain or in enamel is of the most delicate 
description ; much experience and skill are required in it, and with 
every care there are frequent failures ; hence it is attended with con- 
siderable expense. The gilding of porcelain is generally performed 
by applying finely-divided gold mixed up with gum-water and borax ; 
upon the application of heat the gum burns off, and the borax vitrify - 
ing upon the surface causes the gold firmly to adhere ; it is afterwards 
burnished. 
1353. In the manufacture of various kinds of pottery employed in 
the chemical laboratory, and especially in regard to crucibles, many dif- 
ficulties occur ; and many requisites are necessary which cannot be 
united in the same vessel: to the late Mr. Wedgwood we are in- 
debted for vast improvements in this as well as in other branches of the 
art. 
Crucibles-composed of one part of pure clay mixed with about three 
parts of coarse and pure sand, slowly dried and annealed, resist a very  
323 
high temperature without fusion, and generally retain metallic substan- 
ces ; but where the metals are suffered to oxidize, there are few which 
do not act upon any earthen vessel, and some cause its rapid fusion, as 
the oxides of lead, bismuth, Where saline fluxes are used, the 
best crucibles will always suffer, but platinum may often be employed 
in these cases, and the chemist is thus enabled to combat many difficul- 
ties which were nearly insurmountable before this metal was thus ap- 
plied. 
Whenever siliceous and aluminous earths are blended, as in the 
mixture of clay and sand, the compound softens, and the vessel loses 
its shape when exposed to a long-continued white heat, and this is the 
case with the Hessian crucibles : consequently, the most refractory of 
all vessels are those made entirely of clay, coarsely-powdered burned 
clay being used as a substitute for the sand. Such a compound resists 
the action of saline fluxes longer than any other, and is therefore used 
for the pots in glass furnaces. A Hessian crucible lined with purer 
clay is rendered much more retentive ; and a thin china cup or other 
dense porcelain resists the action of saline matters in fusion for a con- 
siderable time. 
Plumbago is a very good material for crucibles, and applicable to 
many purposes : when mixed with clay it forms an infusible compound 
and is protected from the action of the air at high temperatures ; it is 
well calculated for small table furnaces. Wrought-iron crucibles are 
used for the fusion of several metallic substances which melt at a bright 
red heat. 
1354. Under the term Lutes a variety of compounds are used by 
the practical chemist for the purpose of securing the junctures of 
vessels or protecting them from the action of heat. Slips of wetted 
bladder, linseed meal made into a paste with gum-water, white of 
egg and quicklime, glaziers’ putty which consists of chalk and linseed 
oil ; and fat lute composed of pipe clay and drying oil well beaten to a 
stiff mass, are very useful lutes for retaining fumes and vapours and 
joining vessels to each other, but earthy compounds are required to 
withstand the action of a high temperature. 
Windsor loam, or an artificial mixture of clay and sand well beaten 
into a stiff paste, and then thinned with wrater and applied by a brush 
in successive layers, to retorts, tubes, gun-barrels, &rc., enables them 
to bear a very high temperature ; if a thick coating is required, great 
care should be taken that the cracks are filled up as it dries, and often 
a little tow mixed up with the lute renders it more permanent and ap- 
plicable. If the lute is intended to vitrify, as, for instance, to prevent 
the porosity of earthenware at high temperatures, a portion of borax 
or of red lead may be mixed up with it. 
1355. Mortar, or the cement used in building, is a compound of se- 
veral earthy substances, one of which is always lime : for much valu- 
able information relating to this important subject we are indebted to the 
late Mr. Smeaton (History of the Eddy stone Lighthouse), and an excel- 
lent summary of the principal facts connected with it will be found in 
Aikin’s Dictionary, (Art. Cements.) The ordinary mode of making 
inortar consists in mixing a quantity of common sand with slacked lime, 
without any careful attention to the quantity or purity of the materials ; 
but it has been shown by Mr. Smeaton, that the presence of unburnt 
clay prevents the induration of the mortar, and the sand used in Lon- 
don always contains it; the lime too is often imperfectly burned and seldom duly selected ; that which contains a portion of alumina and 
oxide of iron being preferable to the purer varieties ; hence the ad- 
vantage of Dorking lime, or meager lime, as it is usually called. The 
sand should be sharp and large grained, and perfectly free from salt, 
which always prevents the mixture from becoming hard. The addition 
of calcined ferruginous clay, or calcined basalt, or black oxide of iron, 
gives mortar the property of becoming hard under water. 
The mutual action which the substances constituting the different 
kinds of mortar undergo, has hitherto been but imperfectly examined 
by the chemist; to M. Vicat we are indebted for a curious and impor- 
tant series of investigations upon this subject, and his work may be con- 
sulted with much advantage, by those who are concerned in investiga- 
tions of this nature.—Recherches Experimentales sur les Chaux de Con- 
struction, les Betons, et les Mortiers ordinaires. Paris, 1818. 
ZIRCONIA. 
Section XXXIX. Zirconium. 
1356. The earth zircon, or the oxide of zirconium, is a white insipid 
substance ; specific gravity 4.3 ; it is found in the zircon or jargon of 
Cejdon. It is characterized by insolubility in pure alcalis, but is solu- 
ble in alcaline carbonates. Its combinations with the acids are of 
difficult solubility or insoluble, and have been very little inquired into. 
i. The zircon, or jargon, is a mineral, usually of a grey yellowish, 
or reddish-brown colour, crystallized in octoedrons and four-sided 
prisms, and generally semi-transparent. 
ii. Zirconia is contained in the hyacinth, which is also found in Cey- 
lon, and in various parts of Europe.. Its usual colour is red or reddish, 
and its crystals small flattened octoedra, or four-sided prisms. These 
minerals contain about 70 per cent, of zirconia each, the remainder be- 
ing silica, with a trace of oxide of iron.—Klaproth’s Beitrage, Vol. i., 
pp. 222 and 231. 
1357. Zirconia is obtained by the following process : 
Reduce the stone to a fine powder, having previously heated it to red- 
ness, and quenched it in water. Mix the powder with nine times its 
weight of pure potassa, and gradually project it into a red-hot silver 
crucible, and keep it in perfect fusion for two hours. When the cru- 
cible has cooled, reduce the mass to a fine powder, and boil it in distil- 
led water. Boil the undissolved residue in muriatic acid ; filter, and 
evaporate to dryness ; re-dissolve the dry mass in distilled water, and 
precipitate by carbonate of soda. The carbonate of zirconia which falls 
may be decomposed by heat. 
The following method of obtaining pure zirconia is recommended 
by M. M. Dubois and Silveira.—Annales de Chim. et Phys., xiv. 110 : 
Powder the zircons very fine, mix them with two parts of pure po- 
tassa, and heat them red-hot in a silver crucible for an hour. Treat 
the substance obtained with distilled water, pour it on a filter, and 
wash the insoluble part well ; it will be a compound of zirconia, sili- 
ca, potassa, and oxide of iron. Dissolve it in muriatic acid, and eva- 
porate to dryness, to separate the silica. Re-dissolve the muriates of 
zirconia and iron in water ; and to separate the zirconia which adheres 
to the silica, wash it with weak muriatic acid, and add it to the solution. 
Filter the fluid and precipitate the zirconia and iron bv pure ammonia ;» 
Mode of cb- 
tnjping. 325 
wash the precipitates well, and then treat the hydrates with oxalic 
acid, boiling them well together, that the acid may act on the iron, 
retaining it in solution whilst an insoluble oxalate of zirconia is form- 
ed. It is then to be filtered, and the oxalate washed, until no ij-on can 
be detected! in the water that passes. The earthy oxalate is, when dry, 
of an opaline colour ; after being well washed, it is to be decomposed 
by heat in a platinum crucible. Thus obtained, the zirconia is perfect- 
ly pure, but is not affected by acids. It must be re-acted on by po- 
tassa as before, and then washed until the alcali is removed. After- 
wards dissolve it in muriatic acid, and precipitate by ammonia. The 
hydrate thrown down, when wrell washed, is perfectly pure, and easily 
soluble in acids. 
1358. The composition of zirconia has been estimated by Sir H. 
Davy (Elements of Chemical Phil. p. 361.) at 
GLUCINUM. 
37. 
zirconium 
8 
oxygen. 
45 
Section XL. Glucinum. 
1359. The earth glucina was discovered by Vauquelin in the beryl: 
it also exists in the emerald of Peru. It is white and insipid ; its spe- 
cific gravity = 2.97. It dissolves in caustic potassa and soda, and thus 
resembles alumina, hut differs from yttria. Again it differs from alu- 
mina, hut resembles yttria, in being soluble in carbonate of ammonia : 
it is much more soluble in this solution than yttria. With the acids 
it forms saline compounds of a sweetish astringent taste. 
i. The beryl is found in primitive rocks in many parts of the world, 
but especially fine in Siberia. It is usually transparent, and pale 
green or blue. It crystallizes in six-sided prisms. 
ii. The emerald is principally found in Peru, crystallized in regular 
six-sided prisms, the edges or angles of which are sometimes replaced 
by facets. Its colour is green, and it is either transparent or translu- 
cent. The following are their components parts.—-Vauquelin, Journal 
des Mines, No. xxxvi, and No. xliii: 
Beryl. 
Kmerald. 
G8 . . . 
. . . 64.5 
Alumina 
15 . . . 
... 16 
14 . . . 
... 13 
Oxide of Chrome . 
Ov’idn of iron .... 
... 3 
1 . . . 
2 . . . 
... 1.5 
Wntpr 
o 
100 
100 
iii. Glncina is also found in the euclase, a very scarce Peruvian mi- 
neral, composed, according to Berzelius, of 
Silica 
. 44.33 
Alumina 
. . 31.83 
Glucina ...... 
100.00 326 
THORINUM. 
1360. To obtain glucina from either of these minerals, proceed as 
follows :—Reduce it to a fine powder, and fuse it with thrice its weight 
of potassa ; dissolve in a dilute muriatic acid ; evaporate to dryness ; 
re-dissplve in water, and precipitate by carbonate of potassa. Dissolve 
this precipitate in sulphuric acid and add a little sulphate of potassa, 
and on evaporation crystals of alum will be obtained. These being 
separated, add excess of carbonate of ammonia to the residuary liquor, 
which will retain glucina in solution, but the alumina will be precipitat- 
ed ; filter, and evaporate to dryness, and apply a red heat; glucina re- 
mains. 
1361. From the experiments of Davy, this earth may be regarded 
as consisting of 
2J.3 glucinum 
8. oxygen 
29.3 glucina. 
Section XLI. Yttrium, 
1362. In 1794 Professor Gadolin discovered a new earth in a mine- 
ral from the quarry of Ytterby in Sweden, to which Ekeberg, in 1797, 
gave the name of Yttria. The mineral has since been termed Gadoli- 
nite. Oxide of yttrium, or yttria, may be obtained by the following 
process : Pulverise the mineral and boil in repeated portions of nitro- 
muriatic acid ; evaporate nearly to dryness, dilute with water, and fil- 
ter ; evaporate to dryness, ignite the residue for some hours in a close 
vessel, re-dissolve and filter. To this solution add ammonia, which 
throws down yttria and oxide of cerium ; heat the precipitate red-hot, 
dissolve it in nitric acid, and evaporate to dryness ; dilute with 150 
parts of water, and put crystals of sulphate of potassa into the liquid. 
The crystals gradually dissolve, and, after some hours, a white pre- 
cipitate appears of oxide of cerium, the whole of which must be se- 
parated by a repetition of this process. The liquor is then to be fil- 
tered, and the addition of pure ammonia forms a precipitate of yttria, 
which is to be washed and heated red-hot.—Berzelius in Thomson’s 
Chemistry. Vol. i. p. 357. 
1363. Yttria is insipid, white, and without action on vegetable co- 
lours. It is insoluble in water, but very retentive of it. Insoluble in 
pure alcalis, but readily soluble in carbonated alcalis. It forms salts 
which have a sweetish austere taste, and which have been little exa- 
mined. From indirect experiments it probably contains 25 per cent. 
oxygen ; hence it may be regarded as consisting of 
32 yttrium 
8 oxygen 
40 j'ttria. 
Section XLII. Thorinum. 
1364. In examining some varieties of gadolinite and certain ores ol 
cerium, Berzelius obtained a new metallic oxide, the base of which he 
has called thorinum. The accounts hitherto published of the mode of ASSAY AND ANALYSIS OF METALLIFEROUS COMPOUNDS. 
procuring this substance, are by no means sufficiently clear or circum- 
stantial to enable the student to repeat them, but the process of analy- 
sis of the minerals containing it will be found in the section on the com- 
pounds of thorinum in the ensuing chapter. 
1365. Thorina differs from alumina in being insoluble in solution of 
potassa ; from yttria, by its astringent taste without sweetness, and by 
its neutral solutions affording a precipitate when boiled. From zirco- 
nia it differs in the following properties : 1. After being heated to red- 
ness it is still soluble in acids. 2. Sulphate of potassa occasions no 
precipitate in its solutions. 3. It is precipitated by oxalate of ammonia. 
4. Sulphate of thorina crystallizes, while sulphate of zirconia does not. 
—Thomson, Vol. i. p. 567. 
CHAPTER VI. 
OF THE ASSAY AND ANALYSIS OF' METALLIFEROUS COMPOUNDS. 
1366. The chemical history of the metals, given in the preceding 
chapter of this volume, includes some account of the method of ana- 
lyzing certain of their compounds, hut upon this subject many details 
have necessarily been omitted in the different sections treating of the 
metals individually, in consequence of the numerous digressions that 
such discussion would have introduced ; in the present chapter, there- 
fore, it is proposed to describe such analytical processes as have not 
previously been adverted to, and are of frequent occurrence in the 
chemical laboratory ; and likewise to point out the means of detecting 
impurities and adulterations in the various chemical products used in 
medicine and in the arts. 
1367. It is scarcely necessary to observe that in all analytical ope- 
rations distilled water is to be employed, and that the purity of thei 
tests and re-agents must be previously ascertained : it is also conve-t( 
nient that they should be of some known degree of strength or con- 
centration. 
1368. Among the most important apparatus of the chemical analyst, 
is a good balance ; he will generally find it convenient to employ two ; i 
one, extremely delicate and capable of weighing from one-hundredth 
of a grain up to fifty grains ; the other, less sensible, but turning with 
one-tenth of a grain, when loaded with about an ounce in each scale. 
Larger balances are often requisite for weighing from one ounce to 
five or six pounds. 
1369. For the disintegration of very hard substances, mortars of hard i 
steel, agate, or phorphyry, are generally used, and the substance should 
be accurately weighed before and after pulverization, in order to ascer- 
tain whether it has suffered any increase from the abrasion of the mor- 
tar. The aggregation of many very hard stony substances may be di- 
minished by heating them red-hot and quenching in water; but care 
should be taken to ascertain the nature and quantity of any loss which 
they may sustain in this operation. 
1370. The proportion of any substance for an analysis varies, in 
ordinary cases, >"rom twenty to one hundred grains ; fifty grains is, ge- 
nerally speaking, a convenient quantity, and where there is no scarcity 
of the material it is often advantageous to operate upon two or three 
portions at once, using each portion for ascertaining a distinct compo- 
nent part. 
Distilled wa- 
ter. 
Balance- 
Mortars. 
• Quantity, BLOW-PIPE. 
Crucibles. 
1371. The crucibles employed in these analytical operations are 
either metallic, earthenware, or porcelain. Of the former, platinum, 
silver, and iron are chiefly useful; platinum resists the action of the 
greater number of acids, but it is acted upon by alcaline substances ; 
pure silver is chiefly useful for alcaline fusions, but as it melts at a red 
heat, some care is requisite in its employment; for metallic substances, 
Hessian and Wedgwood crucibles are required; the former, when 
well made, resist a very high heat without fusion, and bear sudden 
changes of temperature ; the latter are apt to crack, and should there- 
fore be carefully heated, or placed in a Hessian crucible. It is often 
necessary to line a crucible with charcoal, which is most conveniently 
effected by mixing finely-powdered charcoal with a very little linseed- 
meal, and beating it into a stiff paste with a small addition of water ; 
the crucible is then dipped into water, and its interior lined to the re- 
quisite thickness; on applying heat, the linseed-meal burns, but the 
coating is not injured. 
1372. In the examination of mineral sub- 
stances, the blow-pipe is a most useful and 
necessary auxiliary to our other operations ; 
it affords a simple and convenient means of 
heating to a very high degree, and almost in- 
stantaneously, any substance sufficiently small 
to be enveloped in its flame ; and the expe- 
rienced eye is thus frequently enabled to 
anticipate, with much precision, the nature 
of the substance submitted to experiment. 
There are numerous forms of the blow- 
pipe, among which, that represented in the 
annexed cut is perhaps the most conveni- 
ent. It consists of a brass tube a, with an 
ivory mouth-piece b; the other end of the 
tube terminates in a circular box, from 
which issues the small tube d, moveable in 
any direction round the centre c, by which 
any degree of obliquity may conveniently 
be given to the flame; e is a brass jet which 
fits upon the tube d. 
1373. The following observations respect- 
ing the use of the blow-pipe, and its action 
upon several substances, are extracted from 
Mr. Children’s Essay on Chemical Analysis: 
a work from which the student may derive 
much valuable information. 
A continued stream of air is absolutely 
essential, to produce which, without fatigue 
to the lungs, an equable and uninterrupted 
inspiration must be maintained by inhaling air 
through the nostrils, yvhilst that in the mouth 
is forced through the tube by the compres- 
sion of the cheeks. A little practice will 
make this operation easy, but at first consi- 
derable lassitude is generally experienced 
in the buccinator muscles. After habit has 
Elowpipe. 
Management 
of the blow- 
pipe. FLUXES FOR THE BLOW-PIP'S. 
rendered the operation familiar, a current may be kept up for ten 
or fifteen minutes, without inconvenience. A large wax candle sup- 
plies the best flame, which being urged by the blast, exhibits two dis- 
tinct figures; the internal flame is conical, blue, and well defined, at 
the apex of which the most violent degree of heat is excited ; the ex- 
ternal is red, vague, and undetermined, and of very inferior tempera- 
ture to the formers 
The substance to be submitted to the action of the blow-pipe, which 
should not be larger than a small pepper-corn, must be supported ei- 
ther on charcoal, or a slip of platina or silver foil, or be held in a pair 
of platina pincers. In the first case it may be placed in a cavity in the 
charcoal, and another piece laid over it to prevent its being carried off 
by the blast. The metallic supports are used when the subject of the 
experiment is intended to be exposed to the action of heat only, and 
might be altered by contact with the charcoal. If a very intense heat 
be required the foil may be laid on charcoal. Salts and volatile sub- 
stances, are to be heated in glass tubes, closed at one end, and enlarg- 
ed according to circumstances, so as to form small matrasses. 
The exterior flame should first be directed on the substance, and 
when its action is known, then the interior blue flame. Notice should 
be taken, whether the matter decrepitates* splits, swells up, liquefies, 
boils, vegetates, changes colour, smokes, is inflamed, becomes obedient 
to the magnet, fyc.* ; when the action of heat alone has been ascer- 
tained, it will be necessary to examine what further change takes 
place, by fusing it with various fluxes, and also whether it be capable 
of reduction to the metallic state. 
The three most useful fluxes, are the triple phosphate of soda and 
ammonia, subcarbonate of soda and borax. These are to be kept rea- 
dy pulverised, and when used, a sufficient quantity may be taken up 
by the moistened point of a knife ; the moisture causes the particles 
to cohere and prevents their being blown away, when placed on the 
charcoal. The flux must be melted into a clear bead, and the substance 
then placed on it, and submitted, first to the action of the exterior, and 
then to that of the interior, flame. The appearances which ensue 
must be observed ; as, 
Fluxes. 
*M. Hauy has proposed the following ingenious method of rendering very weak magnetic at- 
tractions perceptible: 
If we conceive the needle to be removed a little from the plane of its magnetic meridian, 
its directing force will immediately tend to restore it, and with a power proportionate to the size 
of the angle which the needle makes with the magnetic meridian. Before any substance can act 
on the needle, it will have to overcome the directing force, as well as the friction at the point of 
suspension; obstacles which may prevent the effect of very slight attractions from being per- 
ceived. To diminish the force opposed to the action of the needle, M. Hauy places a magnet- 
ic bar at a certain distance from it, on the same level and in the direction of its axis, but with its 
poles situated contrary to those of the needle. If we suppose the magnetic bar to be placed to the 
south of the needle, the south pole of the magnet and the needle will be opposed to each other, 
and if the magnet be made to approach the needle, the latter will move on its centre towards 
one side or the other, till an equilibrium is produced between the mutual action of the magnet 
and needle, and that of the needle and the earth. Coulomb lias shown that in proportion as 
the needle deviates from its natural position, the increments of power necessary to produce 
equal etleqts, are in a decreasing ratio; so that when it has moved through nearly a quarter of 
a circle, a very small attractive power will be sufficient to influence it. When it is in this po- 
sition, that is," nearly at right angles with the magnetic meridian, the needle is in its most 
sensible State; and is affected if any substance containing the most minute portion of iron be pre- 
sented to it. 
Hauv has by this method detected iron in several minerals where its presence was not sus- 
pected, or where it was supposed to exist in a state not liable to be affected by tire magnet. 
—Annals of Philosophy, Vol. xii. p. 117. 1st. If the substance be dissolved, and whether with or without 
effervescence : 
2nd. The transparency, and colour of the glass whilst cooling ; 
3rd. The same circumstances, when cold ; 
4th. The nature of the glass formed by the exterior flame j 
bth. Also, by the interior flame. 
6th. The particular appearances with each of the fluxes. 
Subcarbonate of soda does not form a bead on charcoal, but with a 
certain degree of heat is absorbed ; it must therefore be added in very 
small quantities, and a gentle heat used at first, which will promote 
combination without the absorption of the alkali. Some minerals com- 
bine readily with very small portions of soda, but difficultly if more be 
added, and are absolutely infusible with it in great excess; and when 
tiie substance has no affinity for this flux, it is absorbed by the charcoal, 
and no combination ensues. 
When the mineral contains sulphur or sulphuric acid, the glass ac- 
quires a deep yellow colour, which by the light of a lamp appears red, 
as if produced by copper. 
If the glass bead become opaque as it cools, so as to render the co- 
lour indistinct, it should be broken and a part of it mixed with more of 
the flux, till the colour becomes purer, and distinct. To make the co- 
lour more perceptible, the bead may be flattened whilst soft, or drawn 
out to a thread. 
If it be Avished to oxidate a metallic substance, combined with either 
of the 'fluxes, the glass is first heated intensely, and when fused, gra- 
dually withdrawn from the point of the blue flame, and the operation 
repeated, as often as necessary, using a jet of large aperture. The 
addition of a little nitre also assists the oxidation. For the reduction 
of metallic oxides, the glass bead is to be kept in fusion on charcoal, 
as long as it remains on the surface and is not absorbed, that the metal- 
lic particles may collect into a globule. It is then to be fused with an 
additional quantity of soda, which will be absorbed by the charcoal, 
and the spot where the absorption has taken place, strongly ignited by 
a tube with a small aperture. By continuing the ignition, the portion 
of metal which was not previously reduced, will now be brought to the 
metallic state, and the process may be assisted, by placing the bead in 
a smoky flame, so as to cover it with a soot that is not easily blown oft. 
The beads which contain metals frequently have a metallic splendour, 
which is most easily produced by a gentle, flattering, smoky flame, 
when the more intense heat has ceased. With a moderate heat the 
metallic surface remains ; and by a little practice it may generally be 
known whether the substance under examination contains a metal or 
mot. But the glass of borax alone sometimes assumes externally a me- 
tallic appearance. 
When the charcoal is cold, that part impregnated with the fused masf 
should be taken out with a knife, and ground with distilled water in an 
agate mortar. The soda will be dissolved ; the charcoal will float, and 
may be poured off; and the metallic particles will remain in the water, 
and may be examined. 
In this manner most of the metals maybe reduced. 
Action of the Blowpipe on the Earths and Metallic Oxides. 
Baryta (627), when containing water, melts and spreads on the cbaT* 
•ACTION OF THE BLOW-PIPE ON VARIOUS SUBSTANCES. 
coal. Combined with sulphuric acid, it is converted, in the interior 
flame, into a sulphuret, and is absorbed by the charcoal, with efferves- 
cence, which continues as long as it is exposed to the action of the in- 
strument. 
Strontia (652), if combined with carbonic acid, when held in small 
thin plates with platinum forceps in the interior flame, has its carbonic 
acid driven off, and on the side of the plate furthest from the lamp, a 
red flame is seen, sometimes edged with green, and scarcely percepti- 
ble but by the flame of a lamp. Sulphate of strontia is reduced in the 
interior flame to a sulphuret; dissolve this in a drop of hydrochloric 
acid, add a drop of alcohol, and dip a thin slip of deal in the solution ; 
it will burn with a fine red flame. 
Lime (618).—The carbonate is easily rendered caustic by heat; it 
then evolves heat on being moistened, turns paper stained with turme- 
ric brown, and is infusible before the blow pipe. The sulphate is easily 
reduced to a sulphuret, and possesses, besides the property of combin- 
ing with fluor spar at a moderate heat, forming a clear glass. The fluor 
should be rather in excess. 
Magnesia (671) produces, like strontia, an intense brightness in the 
flame of the blow-pipe. A drop of a solution of cobalt being added to 
it, and then dried and strongly ignited, a faint flesh red colour, scarcely 
visible by the light of a lamp, is produced. 
Magnesia may in this manner be detected in compound bodies, if they 
do not contain much metallic matter, or a quantity of alumina, exceed- 
ing that of the magnesia. Some inference, as to the proportion of the 
mugnesia, may be drawn from the intensity of the colour produced. 
All these alkaline earths, when pure, are readily fusible with the 
fluxes, into a clear, colourless glass, without effervescence ; but on add- 
ing a further quantity of the earth, the glass becomes opaque. 
Alumina (1339) combines more slowly with the fluxes than the pre- 
ceding earths, and forms a clear glass, which does not become opaque. 
But the most striking character of alumina is the bright blue colour it 
acquires from the addition of a drop of nitrate of cobalt, after having 
been dried and ignited for some time. It may thus be detected in com- 
pound minerals where the metallic substances are not in great propor- 
tion, nor the quantity of magnesia large. 
The following, according to Berzelius, is a ready method of disco- 
vering lithia (609) in any mineral supposed to contain it; it is founded 
on the facility with which that alkali attacks platinum. 
Take a morsel of the mineral, about the size of a pin’s head, or a 
small quantity of it reduced to fine powder, and heat it with an excess 
of soda, on a slip of platinum foil before the blow-pipe, and keep it red 
hot for about two minutes. The stone will be decomposed, the soda 
will expel the lithia from its combination, and the excess of alkali, be- 
coming fluid at this temperature, will spread over the surface of the foil, 
and envelope the decomposed mass. The platinum round the fused 
alkaline mass assumes a dark colour, deep and extensive in proportion 
to the quantity of lithia in the mineral. The platinum beneath the al- 
kali is not oxidated, but only in those parts where it is in contact both 
with the air and the lithia. Potassa destroys the action of platinum on 
the lithia, if it be not in considerable quantity. The metal recovers 
its brilliancy after being well washed with water and heated to redness. 
—Annales de Chimie, Vol. x. p. 104, note. ACTION OP THE BLOW-PIPE 
Metallic Oxides and Acids. 
Arsenic (1013) flies off" accompanied by its characteristic smell, re- 
sembling garlic. When large pieces of white arsenic are heated on 
ignited charcoal, no smell is perceived. To produce this effect, the 
white oxide must be reduced by being mixed with powdered charcoal. 
If arsenic be suspected in a solution, it may be discovered by dipping 
into it a piece of pure and well-burnt charcoal, which is afterwards to 
be dried and ignited. 
Chromium.^*-Its green oxide (1081) exhibits the following proper- 
ties : it is fusible with microcosmic salt (phosphate of soda and ammo- 
nia) in the interior flame, into a glass which at the instant of its removal 
from the flame is of a violet hue, approaching more or less to dark 
blue or red, according to the proportion of the chromium. After cool- 
ing, the glass is bluish green, but less blue than copper glass. In the 
exterior flame the colour becomes brighter, and less blue than the for- 
mer. With borax it forms a bright yellowish or yellow red glass in the 
exterior flame ; and in the interior flame this becoiqes darker and 
greener, or bluish green. 
Molybdic acid (1071) melts by itself upon the charcoal with ebulli- 
tion, and is absorbed. In a platinum spoon it emits white fumes, and 
is reduced in the interior flame to molybdous acid, which is blue, but 
in the exterior flame it is again oxidated and becomes white. With 
microcosmic salt, in the exterior flame, a small proportion of the acid 
gives a green glass, which by gradual additions of the acid passes 
through yellow green to reddish, brownish, and hyacinth brown, with 
a slight tinge of green. In the interior flame the colour passes from 
yellow-green, through yellow-brown, and brown-red, to black ; and if 
the proportion of acid be large, it acquires a metallic lustre, like 
the sulphuret, which sometimes remains after the glass has cooled. 
Molybdic acid is but sparingly dissolved by borax. In the exterior 
flame the glass acquires a grey-yellow colour. In the interior flame 
black particles are precipitated from the clear glass, leaving it almost 
colourless when the quantity of molybdenum is small, and blackish 
when the proportion is large. If to a glass formed of this acid and 
microcosmic salt a little borax be added, and the mixture fused in the 
exterior flame, the colour becomes instantly reddish-brown ; in the 
interior flame, the black particles are also separated, but in smaller 
quantity. By long-continued heat the colour of the glass is diminish- 
ed, and it appears yellower by the light of a lamp than by day-light. 
This acid is not reduced by soda in the interior flame. 
Tungstic Acid (1095, p. 274.) becomes upon charcoal at first brown- 
ish yellow, is then reduced to a brown oxide, and lastly, becomes black 
without melting or smoking. With microcosmic salt it forms in the in- 
terior flame a pure blue glass, without any violet tinge ; in the exterior 
flame this colour disappears, and appears again in the interior. With 
borax, in the internal flame, and in small proportion, it forms a colour- 
less glass, which by increasing the proportion of acid, becomes dirty 
grey, and then reddish. By long exposure to the external flame it is 
rendered transparent, but as it cools it becomes muddy, whitish, and 
changeable into red when seen by day-light. It is not reduced. 
Oxide of Columbium (1108, p. £76.) undergoes no change by itself, 
but is readily fused with microcosmic salt and with borax, into a clear colourless glass, from which the oxide may be precipitated by heating 
and cooling it alternately. The glass then becomes opaque, and the 
•xide is not reduced. 
Oxide of Titanium (992) becomes yellowish when ignited in a spoon, 
and upon charcoal dark brown. With microcosmic salt it gives in the 
interior flame a fine violet-coloured glass, more tending to blue than 
that from manganese. In the exterior flame this colour disappears. 
With borax it gives a dirty hyacinth colour. 
Oxide of Cerium (998) becomes red brown when ignited. When 
the proportion is small it forms with the fluxes a clear, colourless glass, 
which by increasing the proportion of oxide becomes yellowish-green 
while hot. With microcosmic salt, if heated a long time in the inter- 
nal flame, it gives a clear colourless glass. 
With borax, under similar circumstances, it gives a faint yellow- 
green glass while warm, but is colourless when cold. Exposed again 
for some time to the external flame, it becomes reddish yellow, which 
colour it partly retains when cold. If two transparent beads, one of 
the compound with microcosmic salt, the other with borax, be fused 
together, the triple compound becomes opaque and white. The ox- 
ide is volatile.—See Thomson’s Chemistry, Vol. i. p. 408, 5th edition. 
Oxide of Uranium (983). —The yellow oxide by ignition becomes 
green or greenish brown. With microcosmic salt in the interior flame 
it forms a clear yellow glass, the colour of which becomes more in- 
tense when cold. If long exposed to the exterior flame, and frequent- 
ly cooled, it gives a pale yellowish, red-brown glass, which becomes 
greenish as it cools. With borax in the interior flame, a clear, colour- 
less, or faintly green glass is formed, containing black particles, which 
appear to be the metal in its lowest state of oxidation. In the exterior 
flame this black matter is dissolved if the quantity be not too great, 
and the glass becomes bright yellowish-green, and after further oxidation 
yellowish-brown. If brought again into the interior flame, the colour 
gradually changes to green, and the black matter is again precipitated, 
but no further reduction takes place. 
Oxide of Manganese (703) gives with microcosmic salt, in the exte- 
rior flame, a fine amethyst colour, which disappears in the interior 
flame. With borax it gives a yellowish hyacinth red glass. When the 
manganese, from its combination with iron, or any other cause, does not 
produce a sufficiently intense colour in the glass, a little nitre may be 
added to it while in a state of fusion, and the glass then becomes dark 
violet while hot, and reddish violet when cool. It is not reduced. 
Oxide of Tellurium (1002), when gently heated, becomes first yel- 
low, then light red and afterwards black. It melts and is absorbed by 
the charcoal, and is reduced with a slight detonation, a greenish flame 
and a smell of horse-radish. Microcosmic salt dissolves it without be- 
ing coloured. 
Oxide of Antimony (907) is partly reduced in the exterior flame, 
and spreads a white smoke on the charcoal. In the interior flame it is 
readily reduced, either alone or with the addition of soda. With mi- 
crocosmic salt and with borax it forms a hyacinth coloured glass. Me- 
tallic antimony, when ignited on charcoal, becomes covered with ra- 
diating acicular crystals of white oxide. Sulphuret of antimony melts 
on charcoal, and is absorbed. 
Oxide of Bismuth (939) melts readily in a spoon to a brown glass, 
©N VARIOUS SUBSTANCES. 
333 ACTIOS OF THE BLOW-HPE 
which becomes brighter as it cools. With microcosmic salt it forms a 
grey yellow glass, which loses its transparency, and becomes pale when 
cool. Add a further proportion of oxide, and it becomes opaque. 
With borax it forms a grey glass, which decrepitates in the interior 
flame, and the metal is reduced and volatilized. It is readily reduced 
by itself on charcoal. 
Oxide of Zinc (766) becomes yellow when heated, but whitens as it 
cools. A small proportion forms with microcosmic salt, and with bo- 
rax a clear glass, which becomes opaque on increasing the quantity of 
oxide. A drop of nitrate of cobalt being added to the oxide and dried 
and ignited, it becomes green. With soda in the interior flame it is 
reduced, and burns with its characteristic flabie, depositing its oxide 
■upon the charcoal. By this process zinc may be easily detected even 
in the automalite. Mixed with oxide of copper, and reduced, the zinc 
will be fixed and brass obtained. But one of the most unequivocal 
characters of the oxide of zinc is, to dissolve it in vinegar, evaporate 
the solution to dryness, and expose it to the flame of a lamp when it 
will burn with its peculiar flame. 
Oxide of Cadmium (819) is orange yellow, not volatile, and easily 
reduced; it gives no colour to borax.—Annates de Chimie et Phys., 
T om. viii., p. 100. 
Oxide of Iron (722) produces with microcosmic salt, or borax in the 
exterior flame, when cold, a yellowish glass, which is blood-red while 
hot. The protoxide forms with these fluxes a green glass, which by 
increasing the proportion of the metal passes through bottle green to 
black, and is opaque. The glass from the peroxide becomes green in 
the interior flame, and is reduced to protoxide, and becomes attractable 
by the magnet. When placed on the wick of a candle, it burns with 
the crackling noise peculiar to iron. 
Oxide of Cobalt (958) becomes black in the exterior, and grey in the 
interior flame; a small proportion forms with microcosmic salt and 
with borax a blue glass, that with borax being the deepest. By trans- 
mitted light the glass is reddish. By farther additions of the oxides, 
it passes through dark blue to black. The metal may be precipitated 
from the dark blue glass by inserting a steel wire into the mass while 
in fusion. It is malleable if the oxide has been free from arsenic, and 
may be collected by the magnet, and is distinguished from iron by the 
absence of any crackling sound when placed on the wick of a candle. 
Oxide of Nickel (1112) becomes black at the extremity of the ex- 
terior flame, and in the interior greenish grey. It is dissolved readily, 
and in large quantity, by microcosmic salt. The glass while hot is a 
dirty dark red, which becomes paler and yellowish as it cools. After 
the glass has cooled, it requires a large addition of the oxide to pro- 
duce a distinct change of colour. It is nearly the same in the exteri- 
or and interior flame, being slightly reddish in the latter. Nitre added 
to the bead makes it froth, and it becomes red brown at first and after- 
wards paler. It is easily fusible with borax, and the colour resembles 
the preceding. When this glass is long exposed to a high degree of 
heat in the interior flame, it passes from reddish to blackish and opa- 
que, then blackish grey and transparent: then paler reddish grey, and 
clearer ; and lastly, transparent, and the metal is precipitated in small 
white metallic globules. 
The red colour seems here to be produced by the entire fusion or ON VARIOUS SUBSTANCES. 
335 
solution of the oxide, the black by incipient reduction, and the grey 
by the minute metallic particles before they combine and form small 
globules. When a little soda is added to the glass formed with borax, 
the reduction is more easily effected, and the metal collects itself into 
one single globule. When this oxide contains iron, the glass retains 
its own colour while hot, but assumes that of the iron as it cools. 
Oxide of Tin (790), in form of hydrate, and in its highest degree of 
purity, becomes yellow when heated, then red, and when approaching 
to ignition black, If iron or lead be mixed with it, the colour is dark 
brown when heated. These colours become yellowish as the sub- 
stance cools. Upon charcoal in the interior flame, it becomes and con- 
tinues white ; and if originally white, and free from water, it under- 
goes no change of colour by heating. It is very easily reduced with- 
out addition, but the reduction is promoted by adding a drop of solu- 
tion of soda or potassa. 
Oxide of Lead (872) melts, and is very quickly reduced, either 
without any addition, or when fused with microcosmic salt or borax. 
The glass not reduced is black. 
Oxide of Copper (826) is not altered by the exterior flame, but be- 
comes protoxide in the interior. With both microcosmic salt and bo- 
rax it forms a yellow-green glass while hot, but which becomes blue- 
green as it cools. When strongly heated in the interior flame, it loses 
its colour, and the metal is reduced. If the quantity of oxide be so 
small that the colour be not preceptible, its presence may be detected 
by the addition of a little tin, which occasions a reduction of the oxide 
to protoxide, and produces an opaque red glass. If the oxide has been 
fused with borax, this colour is longer preserved ; but if with micro- 
cosmic salt, it soon disappears by a continuance of heat. The copper 
may also be precipitated upon iron, but the glass must be first saturated 
with iron. Alkalies or lime promote this precipitation. If the glass 
containing copper be exposed to a smoky flame, the copper is super- 
ficially reduced, and the glass covered while hot with an iridescent 
pellicle, which is not always permanent after cooling. It is very easily 
reduced by soda. Salts of copper, when heated before the blow-pipe„ 
give a fine green flame. 
Oxide of Mercury, (1149) before the blow-pipe, becomes black and 
js entirely volatilized. In this manner its adulteration may be disco- 
vered. 
The other metals may be reduced by themselves, and may be known 
by their own peculiar character.-— Thomson'’$ Annals, No. Ixi, p. 42# 
at seq. 
1374, Although the principal analyses in the following sections have 
been conducted in the laboratory of the Royal Institution, and are 
therefore the results of actual experiment, there are many difficulties 
in their performance, which practice alone will enable the student to 
overcome, and some fallacies, to which, even with extensive experi- 
ence, he will still find himself liable; among the latter, I cannot help 
adverting to those attractions of the metallic oxides for each other* 
which have been but little studied, but which often present serious 
difficulties to the preceedings of the analyst; where, for instance, se- 
veral earths are held in the same solution, it is extremely difficult to 
effect their complete separation by the agency of those precipitant®;, 336 
PURIFICATION OF NITRE. 
which are generally regarded as throwing down only one of them ; in 
the same way, although water occasions no precipitate in permuriate 
of tin, but throws down the oxide from permuriate of antimony, yet if 
the permuriates be mixed, it is found that the precipitate by water 
contains a very notable proportion of peroxide of tin; and many si- 
milar cases might be adduced. 
The practice of submitting substances of known composition to 
analysis, cannot be too strongly recommended to the chemical student; 
it makes him acquainted with the mutual actions and habitudes of a 
number of bodies, which experience can alone teach, and gives a dex- 
terity of manipulation, and an accuracy in conducting experimental 
inquiries, of which he will find the value when subsequently in the 
pursuit of original investigations. 
Sectkxn I. Of the Compounds of Potassium. 
1375. Pure Potassa (544) should be perfectly soluble in twice its 
weight of water, and the solution should not effervesce upon the addi- 
tion of a few drops of nitric acid, but remain undisturbed and transpa- 
rent. 
If nitric acid cause an effervescence in the solution of potassa, it 
indicates carbonic acid; if a precipitate not soluble in slight excess of 
the acid, it is silica; if a precipitate soluble in slight excess of acid, it 
is alumina. 
The presence of lime in solution of caustic potassa, is shown by neu- 
tralizing it by nitric acid, filtering if necessary, and adding oxalate of 
ammonia, which causes a white cloud ; or, by the production of a pre- 
cipitate of carbonate of lime upon adding solution of bi-carbonate of 
potassa. 
Baryta water should occasion no turbidness in a solution of pure 
potassa; if it occasion a precipitate soluble with effervescence in nitric 
acid, it announces carbonic acid; if insoluble, sulphuric acid. 
1376. Chlorate of Potassa (546) is sometimes mixed with a little of 
the chloride of potassium, which is shown by the addition of solution of 
nitrate of silver occasioning a precipitate, which it does not in the so- 
lution of the pure chlorate. 
1377. Nitrate of Potassa (551).—The quantity of pure nitre in a 
given portion of the rough salt may be learned w ith tolerable accuracy 
by the following process : 
Purification of Nitre.—7 lbs. of rough nitre are accurately weighed, 
and then dissolved by heat in 21 parts of water; when boiling, the 
scum is removed until no more rises, and then the solution is allowed 
to settle for ten minutes or longer. In this wray nearly all the dirt falls 
down, and the clear solution being poured off, is passed through a filter 
of tow into a pan, and set aside to crystallize ; the dirt left behind i« 
added to the scum, and both being diluted, are filtered through paper, 
and the clear solution preserved. Next day the crystals formed in the 
pan are separated and put into funnels to drain, and the mother liquor 
with the filtered solution from the scum. d-c.. are further evaporated 
Characters. ALCALIMETRY. 
337 
arid again left to crystallize. On the second evaporation, impunities 
generally separate from the solution ; these are sometimes oxide of iron, 
or sulphate of lime, but most frequently common salt and nitrate of 
soda. The two first are easily separated by filtration ; the third is best 
separated by evaporating the solution considerably, until much salt has 
been deposited, and then pouring the whole upon a filter of tow ; the 
salt will remain on it, and should be washed by Water to separate the 
nitre, which water should be added to the liquor, and the whole then 
brought to the crystallizing point. When cold, the crystals deposited 
by this solution are to be separated, and more salt separated as before, 
until the mother liquor is divided into common salt and nitre. It fre- 
quently happens that the crystals from the two or three last evapora- 
tions are coloured or contaminated by the adhesion of common salt, 
sulphate of lime, &c.; in this case, they should be re-dissolved and re- 
crystallized with the same precautions as before. Care should be tak- 
en in drying the crystals, especially when small or when hastily formed, 
that no water remain in the interstices or cleavages between them. 
Solution of pure nitre is not rendered turbid either by nitrate of sil- 
ver or nitrate of baryta. 
1378. Gunpowder.—To analyse this compound, boil it with four 
parts of water, edulcorate the residue, dry it at 212®, and weigh ; the 
loss indicates the nitre. The dry residue, composed of charcoal and 
sulphur, may be decomposed by spreading it upon an earthen plate and 
burning oft' the sulphur at the lowest possible heat; the charcoal will 
remain, still however retaining a little sulphur. A more accurate pro- 
cess consists in introducing the mixture into a small retort furnished 
with a stopcock, exhausted, and filled with chlorine ; heat applied vo- 
latilizes the chloride of sulphur and leaves the charcoal, which may 
be washed, dried, and weighed. 
1379. Carbonate of Potassa.—Dr. Henry has given the following di- 
rections for ascertaining the quantity of real alcali contained in the 
rough alcalis of commerce ; the process depends upon their saturat- 
ing power in respect to an acid of known density, and the principle of 
the analysis has been already adverted to (569, 600) ; his directions, 
however, are of such practical utility, that I have, with his permis- 
sion, transcribed them. “ Provide a tube, nine inches and a half long 
and three fourths of an inch internal diameter, provided with a lip for 
the convenience of pouring, and a glass footto support it. 
“ A tube of this kind holds 1000 grains of water, and (which is desi- 
rable) a little more. To graduate it, weigh into it 100 succesive por- 
tions of distilled water at 60° Fahrenheit, of ten grains each ; or, if 
the tube be of equal bore throughout, it may be sufficient to weigh into 
it ten successive portions of water of 100 grains each, dividing each 
of the intermediate spaces into ten parts by a pair of Compasses. 
When 1000 grains of water have been weighed into the tube, a line 
may be drawn with a file, which may be marked 0, the tenth below 
this 10, and so on. 
“ The test acid, which I prefer, is made by diluting one part of oil 
of vitriol of commerce of sp. gr. 1.849, with four parts of water ; con- 
sequently, one fifth part of its weight is concentrated oil of vitriol, and 
its specific gravity is, as nearly as possible, 1.141. Acid of this 
strength does not, on farther dilution, give out any beat, that can be a 
source of inaccuracy. ALCALIMETRY. 
“ When an alcali is to be examined, find, by Dr. Wollaston’s Scale of 
Equivalents, how many grains of oil of vitriol are required to neutral- 
ize 100 grains of what may be considered the proper alcaline ingredi- 
ent of the substance in question. This, in pearlash, is sub-carbonate of 
potash ; in potash, pure potash ; in barilla or kelp, dry sub-carbonate 
of soda. Let us take pearlash as an example. On referring to the 
scale, we find that 100 grains of sub-carbonate of potash are equiva- 
lent to 71 grains of concentrated oil of vitriol*. Put, therefore, into 
the test-tube a quantity of the dilute acid containing 71 grains of con- 
centrated acid, viz., 355 grains ; and to spare the trouble, on any fu- 
ture occasion, of weighing the acid, let a line be drawn with a file on 
the blank side of the tube, at the level of the acid liquor, which may 
be marked Equiv. of Subc. Pot. 
“ Fill up the tube with water to the line marked 0, and mix the acid 
and water completely by pouring them into a lipped glass vessel; stir- 
ring with a glass rod ; and then returning them into the tube. Now as 
the whole 100 measures contain a quantity of oil of vitriol equivalent 
to 100 grains of sub-carbonate of potash, it is obvious that each mea- 
sure of the liquor in the tube is adequate to the neutralization of one 
grain of the sub-carbonate. 
“ Let 200 grains, taken out of a fair average specimen of the pearl- 
ash to be examined, be dissolved in two ounce measures of warm distill- 
ed water, filter the solution ; and wash the filter with two ounce* 
more of water, which is best applied to the margin of the paper, by 
means of a dropping bottle. Add the washings to the solution, and 
having mixed the whole together, pour one half into a tumbler or gob- 
jet, reserving the other half for a repetition of the experiment if ne- 
cessary. 
“ To the liquor in the glass goblet, add the diluted acid very gra- 
dually, making the additions more and more slowly towards the last. 
As soon as the point of neutralization is attained, wliich will be shown 
by the cessation of a change of colour in slips of litmus and of turme- 
ric paper dipped, from time to time, into the liquor, no more acid 
must be added. It is proper, however, the operator should be aware, 
that there will often be an apparent excess of test acid, in consequence 
of the carbonic acid, which is disengaged, acting on the litmus paper. 
'To avoid this source of error, it is advisable, towards the last, to warm 
the liquor, by setting the glass containing it for half an hour near the 
tire, and 'while thus warmed, to add very cautiously the rest of the 
acid required for saturation. This point being attained, the number on 
the test-tube, at the level of the acid remaining in it, shows at once, 
without any calculation, how much per cent, of sub-carbonate of potash 
is contained in the pearlash under examination. In the samples I have 
tried, it has generally been about 80 per cent. 
“ In operating on barilla, kelp, or any variety of the mineral alcali, 
the process is exactly the same, except that as 93| of oil of vitriol are 
equivalent to 100 of sub-carbonate of soda, we must take 93X5=465 
grains, ol sulphuric acid of density 1.141. This may be marked on 
the tube, Equivalent of Subcarbonate of Soda. In a similar manner, 
we may mark on the tube the equivalent of pure potash, viz., 520 
* Dr. Ure makes it 70.4.—Journ. of Science, iv. 119. 
- According to Dr. Ure, 91.4 is the true equivalent.—Journ. of Science, &c. iv. 119. ANALYSIS OF MINERALS. 
339 
grains of the above diluted acid ; and that of pure soda, 783 grains ; 
with any other equivalents, that may be likely to be of use. 
“ Having ascertained the proportion of sub-carbonate of potash in 
any sample of pearlash, it is easy to find, by the sliding scale, its equi- 
valent quantity of pure or caustic potash. Thus, supposing the pearl- 
ash to contain 80 per cent, of sub-carbonate, that number being set to 
sub-carbonate of potash on the scale, the equivalent in pure potash is 
at once seen to be 55. 
“ To determine, by the same graduated tube, the strength of any 
acid whose equivalent is known, (which is the reverse of the foregoing 
process) we must put 100 grains of the acid, with a sufficient quantity 
of water, into a goblet ; and use, for saturating it, its equivalent of any 
alcali. For example, 100 grains of concentrated oil of vitriol requir- 
ing for saturation 108 grains of dry sub-carbonate of soda, dissolve the 
latter quantity of alcali in water sufficient to make up 100 measures of 
solution in the tube ; then pour thealcaline solution to the acid liquor, 
till the latter is neutralized ; and the number of measures which have 
been expended, exactly denote the strength of the acid. 
“ It may sometimes be desirable to know the proportion, not of con- 
centrated or of real acid, but of acid of some inferior degree of den- 
sity, in a specimen of acid. The method of doing this will best be ex- 
plained by an example. Suppose that we wish to know the equiva- 
lent, in muriatic acid of sp. gr. 1.160, to 100 grains of the same acid 
of sp. gr. 1.074 ; find, by the alcaline test, or by referring to the ta- 
bles in the Appendix, how much real acid 100 grains of both those 
acids contain. In acid of sp. gr. 1.160 it will be 23.4 per cent.; in acid 
of sp. gr. 1.074, it will be 11. Then 23.4 : 100 : : 11 : 47. There- 
fore 47 grains of muriatic acid, ofsp.gr. 1.160, are equivalent, in 
acidity, to 100 of sp. gr. 1.074. 
“No chemical operation can be more simple, or more easily managed, 
than the measurement of the strength of alcalis by acid liquors, and of 
acids by alcaline ones, in the way which has been described. The 
test-tube, which is the only instrument, required for that purpose, may 
be had at any glass-house, and may easily be graduated by any person 
who will take the necessary pains. When once accurately prepared, 
it will be found, also, useful for a variety of other purposes, which 
will readily present themselves to the practical chemist.” 
1380. ThQ purified Carbonate of Potassa (569) of the shops should 
be perfectly soluble in twice its weight of cold water. It often con- 
tains silica, sulphate of potassa, chloride of potassium, and carbonate of 
lime. To detect these, dissolve a hundred grains in nitric acid diluted 
with eight parts of water : the silica, if any be present, remains un- 
dissolved : separate the solution into three equal parts ; to the first, 
add nitrate of baryta, which causes a precipitate of sulphate; collect, 
wash, and dry it; 100 parts are equivalent to 74 of sulphate of potas- 
sa: to the second, add nitrate of silver; 100 grains of the precipi- 
tate, washed and dried at a dull red heat, is equivalent to 52 of chloride 
of potassium : to the third, add oxalate of ammonia, and dry the edul- 
corated precipitate at a heat of 300® ; 100 parts are equal to 77 of 
carbonate of lime. 
1381. There are a few mineral substances which eontain potassa ; 
it was first detected in the leucite by Klaproth, whose analysis of that 340 
ANALYSIS OF THE LEUCITE* 
mineral may be advantageously consulted by the student. (Analytical 
Essays, i. 348.) It consists of 
Silica . . . 
Alumina . 
Potassa . . 
. 53.750 
. 24.625 
. 21.350 
99.725 
There are two modes of analysis which may he practised upon such 
minerals ; they may either be directly acted upon by acids : or fused 
with baryta, and afterwards submitted to acid solution. 
a. 100 grains of leucite in very fine powder were digested for six 
hours in muriatic acid, which was then decanted off and the residue 
washed upon a filter, the washings being mixed with the solution. The 
residue weighed 60 grains, (a.) 
b. The muriatic solution was supersaturated with pure ammonia, 
which occasioned a bulky brownish precipitate (6), which was collect- 
ed, washed, and dried ; it amounted to 12.5 grains. 
c. Carbonate of ammonia produced no change in the last-mentioned 
filtrated liquor, which was therefore evaporated to dryness and the 
residue exposed to a red heat in a platinum crucible ; it was then com- 
pletely re-dissolved in water and again evaporated to dryness ; it had 
the characters of chloride of potassium (c), and weighed 41 grains. 
d. The residue a a was fused with three parts of potassa in a silver 
crucible, the fused mass dissolved in water, supersaturated with muria- 
tic acid, evaporated to dryness, and again digested in water ; there re- 
mained 58.5 grains of dry and pure silica. 
e. The precipitate b b was entirely soluble in pure solution of po- 
tassa, with the exception of a trace of oxide of iron. Being again 
thrown down by muriate of ammonia, it was found to be pure alumina. 
f. The chloride of potassium c c was decomposed in a platinum cru- 
cible by sulphuric acid, and it afforded 48 grains of sulphate of potassa, 
which is eqivalent to 26 of potassa. 
The result of this analysis differs in the proportions of the compo- 
nents from that of Klaproth ; it may be stated as follows : 
Silica, a a 
Alumina with a ) , „ 
, c. > b b &, e . 
trace oi iron 
. . 12.5 
Potassa, c c f 
. . 26. 
Loss . 
100. 
1382. It may here be remarked, that the existence of potassa, soda, 
and lithia in minerals, is generally first indicated by the great apparent 
loss which is sustained upon collecting and weighing their precipitahle 
components : thus, if in any case of analysis we lose upon the aggre- 
gate weight of the precipitates, more than 2 or 3 per cent., we may sus- 
pect the existence of the fixed alcalis, and direct our attention accord- 
ingly to their detection. It also generally happens, that minerals which 
contain any considerable proportion of fixed alcaline substances, are 
remarkable for the facility with which they enter into fusion before the 
blow-pipe. COMBINATIONS OF SODIUM. 
Section II. Of the Combinations of Sodium. 
1383. Pure Soda (577) may be tested in the same way as pure po-'i 
tassa. The presence of potassa in soda may be detected by adding to t 
its aqueous solution muriate of platinum, which forms a buff-coloured 
precipitate if potassa be present. 
1384. Chloride of Sodium. (579). The usual impurities of sea salt! 
are muriates of magnesia and lime. Dissolve 100 grains in an ounce 
of water, and add carbonate of ammonia, which throws down carbonate 
of lime, 100 parts of which, washed and dried at 300°, are equivalent 
to 110 of dry muriate of lime (chloride of calcium). Boil the filter- 
ed liquor nearly to dryness, and carbonate of magnesia falls, of which 
100 parts are equal to about 134 of dry muriate of magnesia. 
1385. Sulphate of Soda.—-This salt in the form of crystals, may 
analyzed as follows : Weigh off 100 grains, and introduce it into a pla- 
tinum crucible, previously weighed ; place it in a sand heat, and gra- 
dually give it a red heat for half an hour ; when cold ascertain the loss 
of weight, which is water of crystallization. (a), Pour two ounces of 
water upon the dry salt, and when perfectly dissolved add solution of 
nitrate of baryta as long as it occasions any precipitate ; edulcorate, 
dry, and weigh the sulphate of baryta thrown down (6), of which 100 
parts indicate 34 of sulphuric acid. The filtered liquor contains the 
soda, now in the state of nitrate, and any excess of nitrate of baryta 
that might have been added : evaporate it to dryness, expose the resi- 
due to a red heat for half an hour in a platinum crucible, by which 
the acid will be expelled, and a mixture of soda and baryta remain ; 
pour upon it dilute sulphuric acid, which forms sulphate of soda and 
sulphate of baryta ; the latter, being insoluble, is separated by filtra- 
tion ; the filtered solution of regenerated sulphate of soda should 
afford on evaporation and expulsion of water as above directed, a quan- 
tity of sulphate, exactly equal to that of the process, (a). Thus it 
jvill be found that 100 grains pf sulphate of soda in crystals, afford of 
To distinguish 
soda from pt* 
tassa. 
To purify. 
Analysis of. 
Water . 
Sulphuric acid. . . 
. . . 24.75 
Soda 
. . . 19.25 
1386. Sulphate of soda is seldom sophisticated ; it should not change 
the colour of litmus or turmeric ; it sometimes contains a little iron, 
which interferes with some of its pharmaceutical uses; this may be 
detected by adding tincture of galls to the aqueous solution of the salt, 
slightly acidulated by nitric acid, when it occasions a black cloud. 
Sea salt is discovered in solution of sulphate of soda, by the addition, 
of sulphate of silver ; salts of lime are shown by the precipitate of 
carbonate of lime, occasioned by carbonate of ammonia. Sulphate of 
potassa is recognised by its sparing solubility. 
1387. Carbonate of Soda.—The analysis of kelp and barilla has been 
above referred to. (page 338.) 
The carbonate of soda of the shops (sodce subcarbonas of the Phar- 
macopoeia), often contains sulphate of soda and sea salt; to discover, 
these, saturate a given weight of the salt with pure dilute nitric acid, 
Analysis of. ANALYSIS OF MINERALS. 
and divide the solution into two parts: to one add nitrate of baryta, 
which gives a precipitate of sulphate of baryta ; to the other add ni- 
trate of silver, which throws down chloride of silver, of which 100 
parts, properly washed and dried, are equal to 41 of sea salt. 
If carbonate of soda contain carbonate of potassa, its presence is 
shown by adding to a saturated solution of the carbonate, a saturated 
solution of tartaric acid in excess; a precipitation of crystalline grains 
of bi-tartrate of potassa ensues if potassa be present. 
1388. Bi-carbonate of Soda is frequently mixed with carbonate of 
soda ; and it is difficult to detect the proportion of the latter, in conse- 
quence of the quantity of water in the bi-carbonate, not having been 
accurately ascertained. The composition of the dry bi-carbonate is 
given above. (601). 
1389. Borate of Soda, or borax, is sometimes adulterated by common 
salt, and by alum. To detect these, dissolve a portion of the salt in 
water, and add slight excess of nitric acid. Test this solution by ni- 
trate of silver for the discovery of sea salt; and by nitrate of baryta 
for sulphuric acid. 
1390. There are several minerals which contain soda ; the following 
analysis of the sodalite, by Dr. Thomson, may be taken as an instance 
©f one mode of proceeding in these cases.—Phil. Mag., xxxvii. p. 303 ; 
or, Transactions of the Royal Society of Edinburgh. 
“ 100 grains of the mineral, reduced to a fine powder, wrere mixed 
with 200 grains of pure soda, and exposed for an hour to a strong red 
heat in a platinum crucible. The mixture melted, and assumed, when 
cold, a beautifiul grass-green colour. When softened with water, the 
portion adhering to the sides of the crucible, acquired a fine brownish 
yellow. Nitric acid being poured upon it, a complete solution was ob- 
tained. Suspecting from the appearance which the fused mass assumed, 
that it might contain chromium, I neutralized the solution as nearly as 
possible with ammonia, and then poured into it a recently prepared ni- 
trate of mercury. A white precipitate fell, which being dried and ex- 
posed to a heat rather under redness, was all dissipated, except a small 
portion of grey matter, not weighing quite 0.1 grain. This matter was 
insoluble in acids, but became white. With potash it fused into a co- 
lourless glass. Hence I consider it as silica. This experiment shows 
that no chromium was present. I was at a loss to account for the pre- 
cipitate thrown down by the nitrate of mercury. But Mr. Allan hav- 
ing shown me a letter from Ekeberg, in which he mentions that he had 
detected muriatic acid in sodalite, it was easy to see that the whole 
precipitate was calomel. The white powder weighed 26 grains, indi- 
cating, according to the analysis of Chenevix, about 3 grains of muriatic 
acid. 
“ The solution, thus freed from muriatic acid, being concentrated by 
evaporation, gelatinized. It was evaporated nearly to dryness, the dry 
mass digested in hot water, acidulated with nitric acid, and poured upon 
the filter, was washed, dried, and heated to redness. It weighed 37.2 
grains, and was silica. The liquor which had passed through the filter 
was supersaturated with carbonate of potash, and the copious white 
precipitate which fell, collected by the filter, and boiled, while yet moist, 
in potash-ley. The bulk diminished greatly, and the undissolved por- 
tion assumed a black colour, owing to some oxide of mercury with 
which it was contaminated. The potash-ley being passed through the ANALYSTS OF SODALITE. 
niter, to free it from the undissolved matter, was mixed with a sufficient 
quantity of sal-ammoniac. A copious white precipitate fell, which 
being collected, washed, dried, and heated to redness, weighed 27.7 
grains. This powder being digested in sulphuric acid, dissolved except 
0.22 grain of silica. Sulphate of potash being added, and the solution 
set aside, it yielded alum crystals to the very last drop. Hence the 
27.48 grains of dissolved powder were alumina. 
“ The black residue, which the potash-ley had not taken up, was 
dissolved in diluted sulphuric acid. The solution being evaporated to 
dryness, and the residue digested in hot water, a white soft powder re- 
mained, which, heated to redness, weighed 3.6 grains, and was sulphate 
of lime, equivalent to about 2 grains of lime. 
“ The liquid from which the sulphate of lime was separated, being 
exactly neutralized by ammonia, succinate of ammonia was dropped in, 
a brownish red precipitate fell, which being heated to redness in a co- 
vered crucible, weighed 1 grain, and was black oxide of iron. 
“ The residual liquor being now examined by different re-agents, no- 
thing further could be precipitated from it. The liquid from which 
the alumina, lime, and iron, had been separated by carbonate of potash, 
being boiled for some time, let fall a small quantity of yellow coloured 
matter. This matter being digested in diluted sulphuric acid, partly 
dissolved with effervescence, but a portion remained undissolved, 
weighing 1 grain. It was insoluble in acids, and with potash melted 
into a colourless glass. It was therefore silica. The sulphuric acid 
solution being evaporated to dryness, left a residue which possessed 
the properties of sulphate of lime, and which weighed 1.2 grains, 
equivalent to about 0.7 grain of lime. 
u The constituents obtained by the preceding analysis being obvious- 
ly defective, it remained to examine whether the mineral, according to 
the conjecture of Bournon, contained an alcali. For this purpose 100 
grains of it, reduced to a fine powder, and mixed with 500 grains of 
nitrate of barytes, were exposed for an hour to a red heat in a porce- 
lain crucible. The fused mass was softened with water, and heated 
with muriatic acid. The whole dissolved except 25 grains of a white 
powder, which proved on examination to be silica. The muriatic acid 
solution was mixed with sulphuric acid, evaporated to dryness, the re- 
sidue digested in hot water, and filtered to separate the sulphate of ba- 
rytes. The liquid was now mixed with an excess of carbonate of am- 
monia, boiled for an instant or two, and then filtered, to separate the 
earth and iron precipitated by the ammonia. The liquid was evapo- 
rated to dryness, and the dry mass obtained exposed to a red heat in a 
silver crucible. The residue was dissolved in water, and exposed in 
the open air to spontaneous evaporation. The whole gradually shot 
into regular crystals of sulphate of soda. This salt being exposed to 
a strong red heat, weighed 50 grains, indicating, according Berthol- 
iet’s late analysis, 23,5 grains of pure soda. It deserves to be mention- 
ed, that during this process the silver crucible was acted on, and a 
small portion of it was afterwards found among the sulphate of soda. 
“ This portion was separated before the sulphate of soda was 
weighed. 
“ The preceeding analysis gives us the constituents of sodalite as 
follows: Silica 
Alumina 
. . . 27.48 
Lime 
Oxide of iron 
. . . 1.00 
Soda 
. . . 23.50 
Muriatic acid 
. . . 3.00 
Volatile matter . . . . 
. . . 2.10 
Loss 
100.00 
combinations of lithium. 
“ Mr. Allan sent a specimen of this mineral to Mr. Ekeberg, who 
analyzed it in the course of last summer. The constituents which he 
obtained, as he states them in a letter to Mr. Allan, are as follows : 
Silica 
.... 36. 
Alumina 
Soda 
.... 25. 
Muriatic acid . . . . 
Oxide of iron . . . . 
.... 0.25 
100.00 
“ This result does not differ much from mine. The quantity of 
muriatic acid is much greater than mipe. The lime and the volatile 
matter which I obtained escaped his notice altogether. If we were to 
add them to the alumina it would make the two analyses almost the 
same. No mineral has hitherto been found containing nearly so much 
soda as this. Hence the reason of the name by which I have distin- 
guished it.” 
Section III. Of the Combinations of Lithium. 
1391. Lithium (607) has been found in a very few minerals only. 
It is contained in largest quantity in the triphane or spodnmene, which 
consists of 
Silica 
Alumina * . . . 
Lithia 
A trace of oxide of iron. 
100. 
Triphane has been found in Sweden, in the Tyrol, and in Ireland. 
Its colour is greyish green ; it is translucent, hard, and brittle : specific 
gravity 3.2. It occurs massive, and its structure is lamellar, and fib- 
rous. 
Petalite, according to the corrected analysis of M. Arfwedson, con- 
sists of 
Silica .... 
Alumina . . 
Lithia .... 
100. 345 
Petalite has hitherto been found in Sweden only: its colours are 
reddish, greenish, or grayish white. It is translucent, lamellar, and 
hard : specific gravity 2.6. 
1392. These minerals maybe analyzed by the following process : 
Reduce 50 grains, in an agate or steel mortar, to a very fine and impal- 
pable powder, and mix it with thrice its weight of precipitated carbon- 
ate of baryta ; give the mixture a red heat for an hour in a silver cru- 
cible, wash out the contents, add a small excess of muriatic acid, and 
evaporate to dryness ; boil the dry residue in 12 parts of water, and 
filter when cold ; the silica will remain on the filter, and may be wash- 
ed, ignited, and weighed. 
The filtered liquor(a) holds the muriates of baryta, alumina, iron, and 
lithia : add solution of sulphate of ammonia as long as it occasions a 
precipitate, which separate, and wash, adding the washings to the filter- 
ed liquor (6) ; the baryta is thus removed in the state of sulphate. 
To the filtered solution (6) add carbonate of ammonia, to throw 
down the alumina and iron, which collect, and wash, adding the wash- 
ings, to the third filtered liquor (c). The mixed precipitate of alumi- 
na and oxide of iron may be digested in potassa, which takes up the 
former, leaving the oxide of iron to be collected, washed, ignited, and 
weighed. 
Evaporate the filtered solution (c) to dryness, and ignite the residu- 
um in a silver crucible ; the ammoniacal salts are driven off, and pure 
chloride of lithium remains, from which the lithia maybe obtained by 
carbonate of silver, as above stated (607). 
COMBINATIONS OF CALCIUM. 
Aaalysii. 
Section IV. Of the Combinations of Calcium. 
1393. For the manufacture of mortar, lime should be entirely free 
from carbonic acid, the presence of which is ascertained by the effer- 
vescence occasioned on adding muriatic acid to a portion of the lime 
slaked in, and diffused through, water. 
1394. To ascertain the quantity of carbonic acid in carbonate of 
lime, or other carbonate, proceed as follows : Provide a thin light' 
phial, capable of holding about six ounces, with a mouth of half an 
inch diameter : pour into this phial one ounce of nitric acid, diluted 
with its bulk of water, taking care not to soil the neck ; stop it with a 
plug of cotton wool, and counter-balance the whole in the of 
a delicate beam. Having now weighed off 100 grains of the carbon- 
ate, place a hundred grain weight in the scale with the counterpoise, 
and carefully introduce the carbonate, broken into pieces, into the 
acid ; stop the phial loosely wifh the wool, and suffer the carbonate to 
dissolve ; during this operation the carbonic acid will escape through 
the cotton plug, which prevents any particles of liquid being thrown 
out during the effervescence, and the counterpoise scale will prepon- 
derate in consequence of the loss of weight sustained by the carbonate 
from the evolution of its carbonic acid. When the solution is complete, 
open the phial, and blow through it by a glass tube, so as to displace 
the included atmosphere ; replace the plug, and bring the balance to 
Quantity of 
carbonic acid. ANALYSES OF THE 
an equipoise by adding weights to the scale containing the phial, which 
weights will show the quantity of carbonic acid lost by 100 grains of 
the carbonate. If pure carbonate of lime be employed, the loss will 
amount to 44 grains. 
1395. We will suppose, however, that a limestone has been ope- 
rated on not perfectly soluble in the acid, and containing magnesia and 
alumina ; the other steps of the analysis are as follow : 
The insoluble portion must be separated by decantation, collected 
upon a filter, washed and dried, the washings being added to the origi- 
nal solution. It is probably silica. 
The solution we will suppose to contain lime, magnesia, and alumi- 
na ; to separate these earths, add carbonate of potassa in very slight 
excess; boil the mixture, collect and wash the precipitate, which will 
consist of the carbonates of lime and magnesia, and alumina ; digest it 
while moist in solution of pure potassa, which dissolves out the alumi- 
na ; pour the whole upon a filter, washing the insoluble portion and 
add to the filtered liquid (which is the alcaline solution of alumina) a 
slight excess of oxalic acid ; collect, wash, and dry the precipitate, at 
a red heat, in a platinum crucible, and weigh it; it is pure alumina. 
The separation of the magnesia and lime may be effected by the pro- 
cess above described (699). 
1396. The analysis of sulphate of lime (633) may be effected by an 
alcaline carbonate as follows : 
Reduce 50 grains of the sulphate to a very fine powder, and boil it 
for half an hour in a Florence flask, with 100 grains of carbonate of 
soda, dissolved in four ounces of water ; the lime will thus be con- 
verted into carbonate, which, collected upon a filter, washed, and dried 
at 500°, will give either by inference, or analysis, the proportion of 
lime, 
The filtered solution will contain the sulphuric acid of the sulphate, 
the quantity of which may be learned by adding muriate of and 
digesting the precipitate in dilute muriatic acid, to remove any carbo- 
nate of baryta ; the insoluble residuum, washed and duly dried, gives 
the equivalent of the sulphuric acid. 
The proportion of water of crystallization in the sulphates of lime, 
may be arrived at by exposing 100 parts in fine powder, to a red heat; 
the loss indicates the quantity of water per cent. 
1397. The analysis of a mixture of carbonate and phosphate of lime 
may be performed in the following manner : 
Dissolve in dilute nitric acid, and add pure ammonia to the solution, 
which causes a precipitate of phosphate of lime, equivalent, when 
dry, to that existing in the original mixture. 
Having separated the phosphate by filtration, add carbonate of am- 
monia, which throws down carbonate of lime ; collect, wash, and dry 
it. 
1398. It is generally supposed that the quantity of acid and of base 
in phosphate of lime may be learned by the following process : Dis- 
solve 50 grains of the phosphate in as small a quantity as will take it 
up of nitric acid, diluted with its bulk of water : to this solution add 
oxalate of ammonia, which will cause a precipitate of oxalate of lime, 
which may be separated, ignited to whiteness, and weighed ; it gives 
the pure lime. 
Phosphate of ammonia is retained in the solution, which, evaporat- 
Analysis of 
sulphate of 
lime. COMPOUNDS OF BARYTA. 
ed to dryness, and heated red hot in a platinum crucible, gives pure 
phosphoric acid : or, the solution may be decomposed by the addition 
of nitrate of lead ; which gives an insoluble phosphate of lead, of 
which 100 parts indicate about 20 of phosphoric acid. But phosphate 
of lime is only partially decomposed by oxalate of ammonia and nitrate 
of lead. Phosphate of lime boiled with carbonate of potassa, gives 
rise to the production of carbonate of lime and phosphate of potassa. 
1399. No accurate analysis has hitherto been made of jiuor spar 
(646) ; and we are ignorant of the nature of the colouring principle 
of the blue variety ; it fades by exposure to light, and is destroyed b}r 
a heat below redness. 
When 100 grains of pure and colourless fluor spar, previously heat- 
ed red hot, are boiled to dryness in a silver crucible, with 200 of sul- 
puric acid, and the dry mass exposed to a red heat, 190 parts of dry 
sulphate of lime are obtained, equivalent to about 78 of lime. If we 
regard fluorspar as a fluoride of calcium, the 78 of lime being equi- 
valent to 56 of calcium, would give the composition of that substance 
56 calcium 
44 fluorine 
and 56 : 44 : : 20 : 15.7. Upon this datum the number 16 has been 
above adopted as the representative of fluorine. 
1400. The number 28., as the equivalent of lime, is that given by 
Dr. Wollaston in his valuable observations upon the synoptic scale of 
chemical equivalents, and regarding it as containing one third the quan- 
tity of oxygen existing in the proportion of sulphuric acid that com- 
bines with it to form sulphate of lime, the number 20 may be regarded 
as the correct equivalent of calcium. 
Section V. Of the Compounds of Barium. 
1401. By dissolving 100 grains of native carbonate of baryta (648), 
previously dried at a red heat, in muriatic acid, with the precautions 
above-directed (1393), they will be found to lose 22 grains of carbonic 
acid ; hence the carbonate consists of 
Baryta 
Carbonic acid . . 
. . 22 
100 
If we now precipitate the muriatic solution by carbonate of ammo- 
nia, collect the precipitate and dry it at a dull red heat, we shall find 
it to weigh 100 grains, showing that the composition of the native and 
artificial carbonate is similar. 
If we precipitate the muriatic solution by dilute sulphuric acid, the 
precipitate of sulphate of baryta properly dried weighs 118 grains ; 
hence the artificial sulphate is composed of 
Baryta 
. . 78 
G6 
Sulphuric acid , 
. . 40 
34 
.118 
too COMPOUNDS OP STRONTIUM. 
100 grains of carbonate of baryta dissolved in nitric acid, evaporated 
to dryness, and exposed for half an hour to a red heat, gave 78 grains 
of pure baryta. 
1402. These results, which closely agree with the original analyses 
of Dr. Withering {Phil. Trans., 1784), and of Klaproth, (Analytical 
Essays, i.) furnish the number 78. as the representative of baryta, for 
in respect to the sulphate, 40 : 78 : : 40 : 78. The number 78. above 
adopted as the equivalent of baryta, is the mean of three analyses, and 
probably very near perfect correctness. Deducting from this number 
one third of the weight of the oxygen in sulphuric acid = 8 gives 70 
as the theoretical equivalent of barium. 
1403. The only compound mineral hitherto discovered containing 
baryta, is the harmotome or cross-stone; in that from Andreasberg, 
Klaproth found 
Silica 
49 
Alumina 
Baryta . 
Water 
98 
The analysis of this compound may be made by fusing it in fine pow- 
der with potassa, solution in muriatic acid, and evaporation to dryness ; 
pour water upon the dry mass, which leaves silica ; to the solution add 
sulphate of ammonia, which throws down the baryta in the state of sul- 
phate ; separate it by a filter, evaporate the filtered liquor to dryness, 
and give it a red heat; re-dissolve the dry residue in water, and add 
ammonia, which throws down alumina. 
Section VI. Of the Compounds of Strontium. 
1404. The analysis of the sulphate and carbonate of strontia may be 
performed in the same way as that of the corresponding compounds of 
baryta. 
1405. Strontia has been found by Mr. Stromeyer in some varieties 
of arragonite (643), and where it exists in small proportion with car- 
bonate'of lime, its presence is not easily detected. 
I dissolved 5 grains of carbonate of strontia and 95 of carbonate of 
lime in nitric acid ; added sulphate of ammonia to the solution, collected 
the precipitate, and washed it with repeated affusions of hot water • 
when dry, it weighed 6.3 grains, and was sulphate of strontia. Ignited 
with half its weight of charcoal, and digested in dilute muriatic acid, it 
afforded a solution of muriate of strontia, the properties of which are 
easily distinguished from those of muriate of baryta (669). 
1406. The number 44.0 as the equivalent of strontium, and 52 as 
that of strontia, are deduced from the analyses of the sulphate and of 
th» carbonate. COMPOUNDS OF MAGNESIA. 
Section VII. Of the Compounds of Magnesium. 
1407. When 100 parts of pure crystallized sulphate of magnesia are 
exposed to a red heat for one hour, they lose, upon the average of se- 
veral experiments, 52 per cent, of water of crystallization ; the residue 
is perfectly soluble in water, and consequently no acid has been ex- 
pelled ; if to its aqueous solution we add muriate of baryta, and col- 
lect and dry the precipitate, it will be found to indicate 32.5 of sulphu- 
ric acid ; hence the composition of the crystallized salt; and 
32.7 : 16.3 :: 40 : 19.9 
Hence the number 20. adopted as the representative of magnesia, and 
12. as the theoretical equivalent of its metallic base. 
1408. Besides the adulteration of sulphate of magnesia with sul- 
phate of soda, already adverted to, the salt as it occurs in commerce is 
often deliquescent from the presence of muriate of lime, and muriate 
of magnesia: the presence of muriatic acid i3 shown by sulphate of 
silver ; and of lime, by oxalate of ammonia, or by bi-carbonate of am- 
monia, which does not throw down magnesia. Sea salt is not unfre- 
quently found in considerable proportion, mixed with sulphate of mag- 
nesia, and which is not thus rendered deliquescent: it is recognised by 
its salt taste, by the action of sulphate of silver, and by pouring sul- 
phuric acid upon it, which disengages muriatic vapours, easily known 
by the dense white fumes occasioned by holding a stopper moistened 
with liquid ammonia above the salt. 
I have sometimes found amongst Epsom salt a very considerable 
proportion of the triple sulphate of magnesia and potassa. (687.) It is 
known by its sparing solubility, and by the rhomboidal form of its 
crystals : it occasions a grittiness in the mouth, and is less bitter than 
subphate of magnesia. 
1409. Carbonate of magnesia (693), when precipitated in the usual 
way and dried at 212°, always retains a portion of water, which it 
loses by exposure to a red heat along with its carbonic acid ; the water 
thus retained varies from 16 to 21 per cent. Lime is a very common 
impurity both in carbonate and calcined magnesia, being frequently de- 
rived from sulphate of lime contained in the water used for edulcorat- 
ing the precipitated carbonate. To the calcined magnesia it gives an 
acrid alcaline taste. The presence of lime is detected by dissolving the 
magnesia or its carbonate in muriatic acid, and adding solution of bi-car- 
bonate of ammonia, which throws down carbonate of lime, but does not 
affect a pure magnesian solution. When carbonate of lime is fraudu- 
lently added to carbonate of magnesia, as is sometimes the case, it is 
detected in the same way. 
The separation of lime and magnesia, when present in the same so- 
lution, has already been adverted to (699). 
1410. The analysis of mineral substances containing magnesia may 
in some cases be performed in the humid way ; but where the stone 1 
resists the action of acids, fusion with alcaline bodies must be resorted 
to. As instances of these analyses, the reader is referred to Klaproth’s 
examination of the chrysolite and of olivin, in the seventh and eighth 
Analysis of 
magnesian 
minerals. ANALYSIS OF THE. 
sections of the first volume of his Analytical Essaijs. The following 
instances may serve further to illustrate the separation of magnesia in 
cases of complex chemical analysis. 
a. 100 parts of red and green-veined primitive serpentine were ex- 
posed to a dull red heat for half an hour, and were found to have lost 
6 grains. 
b. The remaining 94 grains, reduced to fine powder, were digested 
in muriatic acid diluted with two parts of water, and when it no longer 
acted upon the residue it was decanted oft', the residue washed, and the 
washings added to the muriatic solution. The undissolved portion, 
when dried at a red heat, weighed 38 grains, and had the properties 
of pure silica. 
c. The muriatic solution supersaturated with liquid bi-carbonate of 
ammonia afforded a brown precipitate, which was collected, washed, 
and dried ; it weighed 25.5 grains, and was found to contain no alumina ; 
it dissolved entirely and with effervescence in muriatic acid, and this 
solution was evaporated to dryness, the dry residue dissolved in water, 
and this solution precipitated by oxalate of ammonia, yielded oxalate 
of lime, which collected and ignited to whiteness afforded 13 grains of 
pure lime : the liquor from which this oxalic precipitate had been ob- 
tained left after evaporation and ignition 2.5 grains of red oxide of iron, 
equivalent to about 2.2 grains of the black oxide, in which state the 
metal probably exists in serpentine. 
d. The solution from which the precipitate noticed in the last para- 
graph had been separated, was next evaporated to dryness, and the resi- 
due exposed to a red heat in a platinum capsule, till it ceased to lose 
weight; in this way 40 grains of magnesia slightly tinged by an inap- 
preciable purtion of oxide of iron were obtained. 
e. It accordingly appears from the above analysis, that 100 parts oF 
precious serpentine contain. 
A. 
Water 
B. 
Silica 
. . . . 38. 
C. 
Lime 
. . . . 13. 
Oxide of Iron .... 
D. 
Magnesia 
Loss 
100 
Another specimen of serpentine, from the Lizard, lost 7 grains of 
water by heat; (a) digested in muriatic acid, it gave 43.5 grains of si- 
lica ; (6) the muriatic solution was saturated with carbonate of ammo- 
nia, filtered and evaporated to dryness ; the dry residue, after having 
been heated red-hot, gave 30.7 grains of magnesia ; (c) upon the filter 
there remained a precipitate of a brown colour, which was dissolved 
in muriatic acid ; pure ammonia added to this solution, gave a precipi- 
tate weighing 13 grains, and resolved by potassa into 10 grains of pe- 
roxide of iron = 9 protoxide, and 3 grains of alumina, (d) The mu- 
riatic solution, after the separation of the precipitate by pure ammo- 
nia, gave, on adding carbonate of ammonia, 5.3 grains of carbonate of 
lime = 3 grains of lime. This specimen, therefore, of serpentine, 
was composed of COMPOUNDS OF MANGANESE. 
Water 
a 
Silica 
b 
Magnesia 
c 
Oxide of Iron .... 
. . . . 9.0 
c 
Alumina 
d 
Lime 
. . . . 3.0 
96.2 
1411. There are some magnesian stones, such for instance as the 
chrysolite and the olivin, which are so hard as to resist to a considerable 
extent, even when pulverized, the action of muriatic acid : in conducting 
their analysis, they should be previously fused with potassa. If alu- 
mina be present, it may be thrown down from the muriatic solution 
together with the lime, by carbonate of ammonia, and afterwards se- 
parated by the action of solution of potassa. 
Section VIII. Of the Compounds of Manganese. 
1412. The grey radiated ore of manganese (703), when digested in 
line powder in muriatic acid, is entirely dissolved, with the exception 
of a small but variable portion of silica, not exceeding 3 to 4 per cent. 
The solution contains manganese with a small quantity of iron, 
which may be very conveniently separated by the action of ammonia, 
as recommended by Mr. Hatchett, and which, if added so as to satu- 
rate the muriatic acid, throws down the iron, but not the manganese. 
The oxide of iron may be separated by filtration, and ignited with a 
little wax, which, when burned off, leaves protoxide of iron. 
The filtered solution may be evaporated to dryness, and the residue 
moistened with nitric acid, and again evaporated and ignited : it is pe- 
roxide of manganese, the state probably in which the metal exists in 
the above ore. 
1413. Manganese, as has been shown by Mr. Faraday, (Quarterly 
Journal, vi. 357,) readily forms triple salts with ammonia, and as 
these salts are not affected by the fixed alcalis, they are often conve- 
niently formed in those analytical operations the object of which is to 
separate manganese from other metals : Upon this principle he pro- 
poses the following method of decomposing a mixed salt of manganese 
and iron. To a mixed solution of iron and manganese, add solution of 
muriate, sulphate, or nitrate of ammonia, and then pour in pure potas- 
sa ; the iron will be precipitated immediately ; but the manganese will 
remain in solution as a triple salt, unaffected by the free alcalis. 
In this method of analysis the muriate or sulphate of ammonia is 
preferable to the nitrate, because the latter may in some cases pro- 
duce peroxide of manganese, which would be precipitated ; the quan- 
tity of ammoniacal salt added should, for the sake of security, be 
about twice that of the salt of manganese in solution, and as protoxide 
of iron is soluble in ammonia, any excess of that alcali should be 
driven off by heat, to ensure a total precipitation. ANALYSIS OF THE 
1414. The black oxide of manganese, as it occurs in commerce, is 
very often adulterated with chalk, which is detected by digesting a 
given weight of it in nitric acid diluted with 10 parts of water ; if the 
oxide be pure, the acid thus diluted is without any immediate action ; 
if it contain carbonate of lime, an instant effervescence ensues, and a 
nitrate of lime is formed, which may afterwards be decomposed by car- 
bonate of potassa, and the weight of the precipitate when dry shows 
the quantity of the carbonate present. 
Section IX. Of the Compounds of Iron. 
Assay of iron 
ere. 
1415. The assay of those native oxides of iron which are the 
sources of the pure metal, maybe performed as follows : reduce the ore 
to a very fine powder, and mix it with its weight of powdered green- 
bottle glass, half its weight of chalk, and one fourth of charcoal ; ex- 
pose this mixture to the full heat of a wind furnace for about an 
hour; suffer the crucible to cool slowly, and on breaking it, a button 
of metal will be found at the bottom, covered by the other materials, 
fused into a dense slag. If the ore contain any mixed pyrites, it should 
be previously roasted in a muffle or reverberatory furnace. 
1416. The analysis of the magnetic, specular, and hcematitic oxides 
of iron (725) is sufficiently simple, and may be accomplished in the 
following manner: 
a. Reduce the ore to a very fine powder, and mix it in a silver cru- 
cible with three or four parts of liquid potassa; evaporate to dryness, 
and expose the residue for about 15 minutes to a dull red heat ; when 
cold, reduce it to powffler and dissolve in muriatic acid, evaporate near- 
ly to dryness, and boil the residue in wrater ; the silica remains, and 
may be separated by filtration. (b) The filtered solution of permuriate 
of iron may now be evaporated to a small bulk, and decomposed by 
potassa, which added in excess and boiled upon the precipitate, leaves 
peroxide of iron, and which having been washed, dried, and ignited 
with wrax, is restored to the state of protoxide, (c) The filtered alca- 
line liquor now retains alumina, if any were present, which may be 
thrown down b}r muriate of ammonia, washed, and dried. 
It sometimes happens that manganese is present in the muriatic so- 
lution b, and that it is thrown down with the oxide of iron : if this be 
the case, re-dissolve the precipitate, after its treatment by alcali, in 
muriatic acid, and neutralize by ammonia, which throws down the ox- 
ide of iron, but retains that of manganese ; then proceed as directed 
in paragraph 1405. 
1417. Chloride tof Iron (727) was anatyzed as follows: (a) 100 
grains were dissolved in w7ater, and the solution decomposed by ammo- 
nia afforded a precipitate, which when washed, dried, and ignited with 
wax, was black oxide of iron, weighing 56.5 grains, and equivalent to 
44 grains of metallic iron, (fe) The filtered solution from which the 
oxide of iron had been separated was neutralized by nitric acid ; ni- 
trate of silver was then added, and the precipitated chloride of silver 
being collected and ignited weighed 227 grains, which is equivalent to COMPOUNDS OF IRON. 
56 grains of chlorine ; hence it appears that protochloride of iron 
consists of 
44 
iron 
56 
chlorine 
100 
By a similar process, the perchloride of iron may also be anatyzed. 
1418. The native sulphuret of iron, or magnetic pyrites (737), was 
examined by Mr. Hatchett in the following way {Phil. Trans., 1804 ) : 
a. 100 grains, reduced to a fine powder, were digested with 2 
ounces of muriatic acid, in a glass matrass placed in a sand-bath. A 
pale yellowish-green solution was formed. The residuum was then 
again digested with two parts of muriatic acid, mixed with one of nitric 
acid ; and a quantity of pure sulphur was obtained, which, being dried, 
weighed 14 grains. 
b. The acid in which the residuum had been digested, was added to 
the first muriatic solution ; some nitric acid was also poured in, to pro- 
mote the oxidizement of the iron, and thereby to facilitate the precipi- 
tation of it by ammonia, which was added after the liquor had been 
boiled for a considerable time. The precipitate thus obtained was 
boiled with lixivium of potash ; it was then edulcorated, dried, made 
red-hot with wax in a covered porcelain crucible, was completely taken 
Tip by a magnet, and, being weighed, amounted to 80 grains. 
c. The lixivium of potash was examined by muriate of ammonia, 
but no alumina was obtained. 
d. To the filtrated liquor from which the iron had been precipitated 
by ammonia, muriate of barytes was added, until it ceased to produce 
any precipitate ; this was then digested with some very dilute muriatic 
acid, was collected, washed, and, after exposure to a low red heat for 
a few minutes in a crucible of platina, weighed 155 grains. If there- 
fore the quantity of sulphur, converted into sulphuric acid by the pre- 
ceding operations, and precipitated by barytes, be calculated according 
to the accurate experiments of Mr. Chenevix, these 155 grains of sul- 
phate of barytes will denote, nearly, 22.50 of sulphur ; so that, with 
the addition of the 14 grains previously obtained in substance, the to- 
tal quantity will amount to 36.50. 
e. Moreover, from what has been stated it appears, that the iron 
which was obtained in the form of black oxide, weighed 80 grains : 
and, by adding these 80 grains to the 36.50 of sulphur, an increase of 
weight is found = 16.50. This was evidently owing to the oxidizement 
©f the iron, which, in the magnetical pyrites, exists quite, or very 
nearly, in the metallic state, but, by the operations of the analysis, 
had received this addition. The real quantity of iron must, on this 
account, be estimated at 63.50. 
100 grains, therefore, of the magnetical pyrites, yielded, 
*. i 
Sulphur 
SA’ 
) D. 
14. , 
22.50 ' 
| 36.50 grains 
Iron 
E. 
= 
’ 63.50 
100. 
3 B ANALYSES OF THE 
The other varieties of pyrites were analyzed precisely in the same 
way. 
1419. 100 parts of crystallized protosulphate of iron were analyzed 
as follows, in the laboratory of the Royal Institution, (a) The salt 
was reduced to powder, and dissolved in a small quantity of nitric acid ; 
the solution was diluted, supersaturated by ammonia, and filtered. In 
this way the iron was separated in the state of peroxide, amounting to 
28.5 grains, equivalent to 25.5 of protoxide of iron. (6) The filtered 
solution, now perfectly free from iron, but containing excess of ammonia, 
was neutralized by nitric acid, and nitrate of baryta was added till it 
ceased to form a precipitate. The sulphate of baryta thrown down 
was dried at a red heat and weighed 85 grains, indicating 28.7 of sul- 
phuric acid: hence it appears that 100 grains of crystallized protosul- 
phate of iron contain 
25.5 protoxide of iron 
28.7 sulphuric acid 
54.2 
The loss, amounting to 45.8, is to be attributed to water of crystalli- 
zation, for 100 grains of the crystals heated to dull redness for a quar- 
ter of an hour lose about 45 per cent.; hence the salt consists of 
54.2 dry sulphate of iron 
45.8 water of crystallization 
100. 
The data upon which the composition of oxides of iron is founded, 
are given in paragraph 724. 
1420. The analysis of phosphate of iron may be performed as that of 
phosphate of copper, which is given in Section 855. 
1421. The analysis of the different kinds of iron produced by the 
manufacturer is attended with many difficulties, and has hitherto only 
been partially performed : on this subject some useful and interesting 
details will be found in Mr. Daniel’s paper “ On the mechanical struc- 
ture of iron, —Quarterly Journal of Science and Arts, ii. 278. 
1422. Wootz or Indian steel was examined in the laboratory of the. 
Royal Institution by Mr. Faraday, as follows, with a view to detect its 
components, exclusive of carbon and iron. 
A piece of wootz, weighing 164.3 grains, was placed in a flask, and 
acted on by nitro-muriatic acid and heat. It gradually dissolved, and 
dark-coloured flakes, separated from it, which were unalterable in 
the acid, though boiled with it. When all action had ceased, the solu- 
tion was poured off from the sediment (a) which was repeatedly wash- 
ed with distilled water ; the solution was then examined carefully, but 
I could find nothing in it but iron. Whilst washing the sediment (a) it 
separated into two parts ; a black powder (6) sank to the bottom of the 
water poured upon it whilst a reddish brown substance (c) in flocculi 
remained suspended ; these were parted from each other. 
The black powder (6) was fused with potash in a silver capsule, and 
then dissolved in water ; it deposited a brown powder (d), and a clear 
alcaline solution was obtained. This was saturated with muriatic acid, 
and evaporated to dryness, and then being re-dissolved with a little ex- COMPOUNDS OF IRON. 
cess of muriatic acid, a very small quantity of white flocculi were left 
untouched, which were insoluble in acids, and had the characters of 
silex. The solution acted on by subcarbonate of potash give an abun- 
dant precipitate. This was washed, and when heated with a little solu- 
tion of potash, dissolved in it like alumine. Sulphuric acid was then 
added, and a solution of alum was obtained, a small quantity of silex 
precipitating. 
The brown powder (d) deposited by the alcaline solution, Avas treat- 
ed with nitric acid ; a little heat being applied, nearly the whole was 
dissolved immediately, leaving a little of a black substance. The filter- 
ed solution gave a precipitate with muriate of soda, but when ammonia 
was added to it, the precipitate was re-dissolved, and a small quantity 
of iron was thrown down. The solution contained, therefore, silver, 
from the capsule in which the fusion had been made, and iron derived 
from the wootz. The black substance left by the nitric acid, was nearly 
all dissolved, by nitro-muriatic acid, iron being taken into solution, and 
a-little of the substance (&) remaining. 
The redish brown substance (c) was not aifected by nitric acid, but, 
on adding solution of pure potash to it, a clear deep brown solution 
was obtained, and a blackish brown sediment (e) remained. When 
the alcali of the solution was neutralized by muriatic acid, flocculi, 
were precipitated, and the solution became colourless. These flocculi 
collected together and dried, proved to be combustible, and appeared 
to be merely modified tannin. The brown sediment (e) being then 
examined by muriatic acid, gave oxide of iron and a little silex.— 
Quarterly Journal of Science and Arts, vii. 288. 
Section X. Of the Compounds of Zinc. 
1423. The mode of ascertaining the composition of the oxide of 
zinc has been explained above, (767); it is only necessary to guard 
against the impurities of common zinc, which are chiefly iron, lead, 
and copper ; the former is taken up by dilute sulphuric acid, and the 
two latter metals resist its action, and remain in the form of a black 
powder. Add to the sulphuric solution excess of ammonia, and apply 
a gentle heat; the oxide of iron will fall, and upon the addition of 
carbonate of potassa to the ammoniacal solution and boiling it, the pure 
oxide of zinc will be thrown down. 
1424. The oxide of zinc of the Pharmacopoeia is sometimes disco- 
loured by a little iron ; adulterated with chalk, or plaster of Paris ; or 
contaminated by lead and arsenic. The presence of iron is shown by 
its solution in dilute nitric acid, neutralized by ammonia, becoming 
black with tincture of galls ; chalk occasions an effervescence on add- 
ing the acid ; gypsum is dissolved by boiling water, and detected by 
oxalate of ammonia and muriate of baryta. White arsenic is found 
by digesting in acetic acid, and adding solution of sulphuretted hydro- 
gen, which occasions a yellow precipitate, in which arsenic is recog- 
nised by its smell when ignited on charcoal; and lead is shown by a 
black precipitate on adding sulphuretted hydrogen to the acetic solu- 
tion. ANALYSES OF THE 
1425. Analysis of Chloride of Zinc.—100 grains of chloride of zinc, 
obtained by heating the muriate in a glass tube to redness, and weighed 
while hot, to prevent error from deliquescence, were dissolved in water, 
and left 4 grains of oxide of zinc ; accordingly 104 grains of the same 
chloride were dissolved, filtered, and decomposed by nitrate of silver, 
and the precipitate, washed, collected, and dryed at a red heat, weigh- 
ed 203 grains, equal to 50.4 of chlorine. The solution from which 
the chloride was precipitated contained nitrate of zinc, with a little 
nitrate of silver; muriate of ammonia was added to throw down the 
silver, in the state of chloride, which was separated upon a filter, and 
the clear liquor, evaporated to dryness, and ignited, afforded 62 grains 
of oxide of zinc, equivalent to 49.5 grains of metal; hence 100 grains 
of chloride of zinc gave 
50.5 chlorine 
49.5 zinc 
100. 
1426. Analysis of Sulphuret of Zinc.—A specimen of yellow blende 
Was analyzed as follows by Dr. Thomson.—Annals of Philosophy, iv. 94. 
a. 50 grains, in fine powder, were digested for two days in dilute 
nitric acid ; thehvhole was then thrown upon a filter, and the undissolv- 
ed residue, washed and dried at 110°, weighed 26 grains. 
b. These 26 grains were put upon a watch-glass and heated by a 
lamp ; they burned like sulphur, and left a residue of 22.4 grains ; the 
3.6 grains of loss were considered as sulphur. 
c. The 22.4 grains residue, which had now assumed the appearance 
of the original blende, were again digested for two days with dilute ni- 
tric acid : the second day, as all action was over, and the whole nearly 
dissolved, the flask was exposed for some hours to a heat of 130° ; the 
whole was then thrown upon a filter, and the undissolved portion, 
washed and dried, weighed 0.54 grains. 
d. This small residue was burned as before, by which it lost sulphur 
amounting to 0.16 grains, and 0 38 grains of residue remained. 
e. This 0.38 grains had the appearance of small particles of quartz, 
and weighed 0.38 grains. 
/. The two portions of acid liquid, which had been digested on the 
ore, and which contained the greatest part of it in solution, were mix- 
ed together, and almost but not quite, saturated with carbonate of soda. 
A considerable excess of caustic ammonia was then poured in. By 
this alcali the oxide of iron was thrown dovra in yellowish red flocks, 
while the whole of the zinc was held in solution. The oxide of iron 
being separated by the filter, washed, dried, and heated to redness, 
weighed 8.5 grains. Now this is equivalent to 5.98 grains of metallic 
iron. 
g. The residual liquor was now boiled in a glass retort down to half 
its bulk, in order to drive off the ammonia, and precipitate the oxide 
of zinc. About one half of that oxide precipitates after a few minutes’ 
boiling, but it requires considerable concentration before the other half 
falls down. From this circumstance it is not improbable that ammonia 
and oxide of zinc unite in two proportions. 
The oxide of zinc thus obtained being washed, dried, and heated t* SVLPHURETS ©F ZINC. 
357 
redness, weighed 36.4 grains. This is equivalent to 29.32 graias of 
metallic zinc. It may be proper to mention that the oxide of zinc 
thus obtained,was not quite white, but had a slight tinge of green. I 
conceived that this might be owing to the presence of copper, but if 
this metal was actually present, it was in too minute a quantity to be 
detected by the usual tests. 
h. The liquid thus freed from iron and zinc, was mixed with nitric 
acid, till it acquired a perceptibly sour taste. This was done to pre- 
vent any inaccuracy from the presence of ammonia, if any should still 
remain in the liquid. A solution of muriate of barytes was then mix- 
ed with it. The sulphate of barytes which precipitated, being wash- 
ed, dried, and heated to redness, weighed 77.616 grains. Now 77.616 
grains of sulphate of barytes contain 26.4 grains of sulphuric acid, or 
10.56 grains of sulphur. From the preceding analysis it appears that 
blende is composed of the following ingredients : 
Zinc .... 
. . 29.32 
• • • 
. . . 58.64 
Sulphur . . 
. . 14.32 
Iron .... 
. . 5.98 
Quartz. . . 
50.00 
100.00 
1427. I adopted the following process in the analysis of the crystal- 
lized black blende of Derbyshire : 
a. 100 grains carefully separated from its siliceous matrix, were 
reduced to a fine powder, and dried at 600°. The loss of weight 
indicates water. 
b. Upon the dried and pow’dered ore put into a Florence flask, I 
poured 2 ounces of nitro-muriatic acid, consisting of two of nitric and 
one of muriatic acid, in small successive portions, taking care to mode- 
rate the effervescence, and when this had subsided, a sulphureous 
magma floated upon the acid : the flask was placed in a sand heat, and 
with one additional ounce of nitro-muriatic acid, was digested until 
nearly the whole of the sulphur had disappeared, being converted into 
sulphuric acid. The whole contents of the flask were then poured 
into a conical glass, to allow a portion of undissolved matter to sub- 
side, which was separated by decantation, and proved to be silica, 
mixed with a little pure sulphur, the quantity of which was determined 
by burning it off-, and ascertaining the loss of weight. 
c. The decanted acid liquor was now evaporated considerably, so 
as to dissipate a portion of its excess of acid, and the residue divided 
into two equal portions, a and b. To a, considerably diluted with wa- 
ter, I added nitrate of baryta, and the precipitate being collected, washed, 
and dried at a red heat, was pure sulphate of baryta, and was used as 
the equivalent of the sulphur in the ore. 
d. Carbonate of soda was added to the portion b, which threw down 
every thing, and the precipitate composed of the carbonate of zinc 
and peroxide of iron was digested in liquid ammonia, which took up 
the carbonate of zinc, leaving the oxide of iron undissolved. 
e. The alcaline solution of zinc was decomposed by the addition of 
muriatic acid in slight excess, and to the acid muriate of potassa a little 
carbonate of soda was added t® ensure the entire separation of the zinc ; ANALYSES OP THE 
the zinc precipitate was now washed, dried, and ignited to reduce it t® 
the state of pure oxide of zinc. 
/. This ore contained neither copper nor arsenic, which are some- 
times present in it. 
1428. Analysis of Calamine (782).—Mr. Smithson {Phil. Trans., 
1803.) was the first to show that there are two distinct varieties of ca- 
lamine ; the one a true carbonate of zinc, and the other a compound 
of oxide of zinc and silica. 
A specimen of crystallized calamine from Derbyshire afforded in the 
100 parts 
Silica 
0.8 
Oxide of iron . . . . 
1.5 
Oxide of zinc .... 
65.0 
Carbonic acid . . . . 
100. 
The above ore was digested in dilute muriatic acid, in which it 
slowly dissolved with effervescence, with the exception of 0.8 grains 
of silica. The solution was evaporated to dryness, and the dry resi- 
due redissolved perfectly in water, leaving no further portion of silica. 
To this aqueous solution caustic ammonia was added in excess, so as 
to re-dissolve the oxide of zinc at first thrown down, and the whole 
thrown upon a filter, on which there remained 1.5 grains of oxide of 
iron. The ammoniacal solution was supersaturated by muriatic acid, 
and carbonate of ammonia was added to throw down the whole of the 
zinc, which precipitate, being dried and ignited, weighed 65 grains. 
The filtered solution was evaporated to dryness, and the residue being 
heated in a platinum capsule, entirely evaporated, and was merely 
muriate of ammonia. The loss therefore of 32.7 parts in the hundred 
may be regarded as carbonic acid. 
1429. A specimen of electric calamine in small acicular crystals af- 
forded, by digestion in nitric acid, a residue of 38.5 per cent, silica, 
which being separated by a filter, the filtrated liquor evaporated to 
dryness, and the dry mass, ignited for a quarter of an hour, gave 60 
per cent, of oxide of zinc. The loss may be regarded as water, for 
the calamine lost upon ignition 2 per cent, in weight. 
1430. Assay of Zinc Ores.—To ascertain the value of a sample of 
zinc ore, two methods may be resorted to. 1. Pick out the impurities 
and weigh off 1000 grains of the picked ore ; give it a dull red heat 
in a muffle, taking care not to fuse it: mix the roasted ore with half 
its weight of lamp-black, put it into a small coated glass retort with its 
neck drawn to a very small aperture, and give it a red heat for one 
hour ; cool it gradually, and the zinc will be found in drops in its neck. 
2. Prepare and roast the ore as before, and stratify it in a crucible 
with its weight of clippings of sheet copper ; lute a cover on the cru- 
cible, and give it a dull white heat for an hour. When cold, throw 
the contents into water, by which the brass maybe separated from the 
other matter, and its increase of weight compared with the original 
copper gives the addition of zinc. In this process, however, a portion 
of zinc is always lost. COMPOUNDS OF TIN. 
Section XI. Of the Compounds of Tin. 
1431. The native oxide of Tin (792) or tin-stone, in consequence of 
its mechanical aggregation, is almost insoluble in the acids, but it is ren- 
dered soluble by fusion with potassa, as Klaproth first remarked. 
(Analytical Essays, i. 522.) The following is the process given by that 
excellent analyst, and from the relative proportion of the tin to the 
oxygen, it appears that the metal exists in this ore in the state of per- 
oxide. 
a. 100 grains of tin-stone, from Cornwall, previously ground to a 
subtile powder, were mixed in a silver vessel with a lixivium contain- 
ing 600 grains of caustic potash ; this mixture was evaporated to dry- 
ness, and ignited for half an hour ; when the mass thus obtained had 
been softened with boiling water, it left on the filter 11 grains of an 
undissolved residue. 
b. These 11 grains again ignited with six times their weight of caus- 
tic potash, and dissolved in boiling water, left now only 1.25 grains of a 
fine yellowish-grey powder behind. 
c. The alcaline solution (a and b) was saturated with muriatic acid, 
and oxide of tin was thrown down ; this precipitate re-dissolved by an 
additional quantity of muriatic acid was precipitated afresh by means of 
carbonate of soda ; when lixiviated and dried in a gentle heat, it ac - 
quired the form of bright yellowish transparent lumps. 
d. This precipitate being finely powdered, entirely dissolved in 
’ muriatic acid, assisted by a gentle heat. Into the colourless solution, 
previously diluted with from two to three parts of water I put a stick of 
zinc, and the tin thus reduced gathered around it in delicate dendritic 
laminae of a metallic lustre ; these, when collected, washed, dried, 
and fused under a cover of tallow, in a capsule placed upon charcoal, 
yielded a button of pure tin weighing 77 grains. 
e. The above-mentioned residue of 1.25 grains, left by the treat- 
ment with caustic potash (6), afforded with muriatic acid a yellowish 
solution, from which, by means of a little piece of zinc introduced into 
it, 0.5 grain of tin was still deposited; Prussian alcali added to the 
remainder of the solution, produced a small portion of a light blue 
precipitate, of which, after subtracting the oxide of tin now combined 
with it, hardly £ of a grain remained, to be put to the account of the 
iron contained in the tin-stone, here examined. 
In these experiments (excepting only a slight indication of silex 
amounting to about f of a grain), no trace has appeared, either of 
tungstic oxide, which some mineralogists have supposed to be one of 
fcthe constituent parts of tin-stone, nor of any other fixed substance. 
what is deficient in the sum, to make up the original weight 
of the fossil analyzed, must be ascribed to the loss of oxygen; and 
thus the constituent parts of this ore are to each other in the following 
proportion: 
Tin 
Iron 
Silex 
Oxygen . , , 
100. ANALYSIS THE 
1432. Dr. Davy (Phil. Trans., 1812.) in his analyses of the 'Chit- 
rides of Tin (794, 795.) separated the metal by the immersion of a 
plate of zinc ; from 67.5 grains of chloride of tin he thus procured 
42. of metallic tin, whence inferring the proportion of chlorine from 
the loss of weight, he concludes that this chloride is composed of 
62.22 tin 
37.78 chlorine 
In consequence of the volatility of the perchloride of tin, it is very 
difficult to weigh it with perfect accuracy ; it was therefore poured into 
a bottle half-full of water, the weight of which was previously ascer- 
tained, and its quantity inferred by the increase of weight. The wa- 
ter was rendered slightly acid by muriatic acid, and 81.75 grains of the 
perchloride gave by the immersion of zinc 34 grains of tin : hence 100 
of the perchloride may be regarded as consisting of 
42.1 tin 
57.9 chlorine 
The quantity of chlorine in the chloride of tin cannot be ascertained 
by nitrate of silver, in consequence of the reduction of a portion of the 
silver; but having thrown down the zinc, the dissolved chloride of 
zinc may be decomposed by nitrate of silver, and thus the quantity of 
chlorine originally united to the tin may be ascertained. 
1433. The following is Klaproth’s analysis of the Cupreous Sulphu- 
ret of Tin, called tin pyrites, or bell-metal ore, from St. Agnes in Corn- 
wall. 
a. 120 grains of finely triturated tin-pyrites were treated with an 
aqua regia, composed of one ounce of muriatic and \ ounce of nitric 
acid. Within twenty-four hours the greatest part of the metallic por- 
tion was dissolved without heat, while the sulphur floated on the sur- 
face ; after the mixture had been digested for some time in a sand-heat, 
I diluted it with water, and filtered; it left 43 grains of sulphur, still 
mixed with metallic particles ; when the sulphur had been gently burnt 
©ff on a test, there still remained 13 grains ; of which eight were dis- 
solved by nitro-muriatic acid: the remaining part was then ignited 
with a little wax ; upon which the magnet attracted one grain of it. 
What remained was part of the siliceous matrix, and weighed three 
grains. 
b. The solution of the metallic portion (a) was combined with car- 
bonate of potash ; and the dirty-green precipitate thus obtained was 
re-dissolved in muriatic acid diluted with three parts of water ; into 
this fluid a cylinder of pure metallic tin weighing 217 grains was im- 
mersed : the result was that the portion of copper contained in the so- 
lution deposited itself on the cylinder of tin, at the same time that the 
fluid began to lose its green colour, from the bottom upwards, until, 
after the complete precipitation of the copper in the reguline state, it 
became quite colourless. 
c. The copper thus obtained weighed 44 grains ; by digestion in 
nitric acid it dissolved, and left one grain of tin behind in the character 
of a white oxide ; thus the portion of pure copper consisted of 43 grains. 
d. The cylinder of tin employed to precipitate the copper now COMPOUNDS OP CADMIUM. 
361 
weighed 128 grains, so that 89 grains of it had entered into the muria- 
tic solution ; from this, by means of a cylinder of zinc, I re-produced 
the whole of its dissolved tin, which was loosely deposited on the zinc 
in a tender dendritical form. Upon being assured that all the tin had 
been precipitated, I collected it carefully, lixiviated it cleanly, and suf- 
fered it to dry ; it weighed 130 grains. I made it to melt into grains, 
having previously mixed it with tallow, under a cover of charcoal-dust, 
in a small crucible, which done, I separated the powder of the coal by 
elutriation; among the washed grains of tin, I observed some black 
particles of iron, which were attracted by the magnet, and weighed 
one grain ; deducting this, there remain 129 grains for the weight of 
the tin ; by subtracting again from these last, those 89 grains, which 
proceeded from the cylinder of tin employed for the precipitation of 
the copper (6), there remained 40 grains for the portion of tin contain- 
ed in the tin pyrites examined. Hence, including that one grain of tin 
which had been separated from the solution of the copper (c), the por- 
tion of pure tin contained in this ore amounts to 41 grains. 
The educts or substances extracted in this process from tin pyrites 
were consequently 
Sulphur 
Tin 
. . . 41 
Copper 
. . . 43 
Iron 
Vein-stone or gangue . . . 
. . 3 
119 
Which makes, in a hundred parts, 
Sulphur 
25 
Tin 
34 
Copper 
36 
Iron , . 
2 
97 
1434. Assay of Tin Ores.—If the ore contain arsenic, it should be 
powdered, mixed with a little charcoal, and roasted till vapours no long- 
er rise. The residue mixed with a little pitch and sawdust, is to be 
put into a covered crucible, and exposed in a wind-furnace to a bright 
red heat for half an hour ; when cool, break the crucible, and the but- 
ton of metallic tin will be found at the bottom, which may be cleaned 
by gentle hammering and a wire brush, and weighed. The richest 
ores afford about 70 per cent, of metal. 
Section XII. Of the (Compounds of Cadmium, 
1435. We are as yet too little acquainted with the states of combi- 
nation in which cadmium exists in its ores, and with the properties of 
the metal itself, to lay down precise rules for their analysis. 
Mr. Stromeyer directs the digestion of the mixed oxide of zinc and ANALYSIS OF THE 
cadmium in sulphuric acid, and passing through the acidulous solution 
a current of sulphuretted hydrogen gas : re-dissolve the precipitate in 
muriatic acid, evaporate to dryness, dissolve the residue in water, and 
precipitate by carbonate of ammonia, of which add excess to re-dis- 
solve oxide of zinc, and of copper should any be present; carbonate 
of cadmium remains. 
According to Stromeyer, 100 parts of cadmium, when converted into 
oxide, absorb 14.35 of oxygen, and 
14.35 : 100 :: 8 : 55.75 
So that, upon this datum, the number 55.8 may be assumed as the 
equivalent of cadmium ; a number widely different from that given 
above, 819, and 63.8 will be the representative of oxide of cadmium. 
1436. The following are Stromeyer’s analyses of the nitrate, sul- 
phate, and carbonate of cadmium.—Gilbert’s Annalen, lx. ; 
Nitrate .. 
100 nitric acid 
117.58 oxide of cadmium 
Sulphate . 
) 100 sulphuric acid 
| 161.1 oxide of cadmium 
Carbonate 
100 carbonic acid 
292.8 oxide of cadmium 
Now if we deduce the number for the oxide from the mean of these 
experiments, it will be about 64.1, which gives 56 as the equivalent of 
the metal. 
Upon the same authority, the chloride, iodide, and sulphuret of cad- 
mium may each be regarded as composed of one proportional of each 
of their components. 
1437. The Nitrate of Cadmium is a white prismatic deliquescent salt 
composed of 
1 
proportional oxide 64 
1 
acid 64 
4 
—t water, 9X4= 36 
154 
1438. Sulphate of Cadmium forms large prismatic crystals, much 
resembling those of sulphate of zinc ; very soluble and efflorescent, 
undergoing no change at a low red heat, but losing acid when heated to 
a bright red. It consists of 
1 
proportional oxide ....... 
1 
acid 
4 
water, 9 X 4 = . 
. 36 
140 
1439. Carbonate of Cadmium is a white insoluble powder easily de- 
composed at a red heat. It consists of 
1 proportional oxide . . . 
1 — acid . . . . 
86 SULPHURETS OF COPPER. 
Section XIII. Of the Compounds of Copper. 
1440. The method of determining the composition of the Oxides of 
Copper is described in paragraph 827. 
1441. Chloride of Copper (829) was thus analyzed by Dr. Davy.— 
Phil. Trans., 1812. p. 172 : 
a. 80 grains were dissolved in nitro-muriatic acid, and a plate of iron 
was immersed, upon which copper was precipitated, weighing, when 
well washed and perfectly dry, 51.2 grains. 
b. The same quantity of the chloride, dissolved in nitric acid, and 
precipitated by nitrate of silver, afforded 117.5 grains of dry chloride 
of silver. 
c. Since chloride of silver contains 24.5 per cent, of chlorine, 80 
grains of chloride of copper must contain 51.2 grains of copper, (a.) 
and 28.8 of chlorine, and 100 will consist of 36 chlorine -f- 64 cop- 
per. 
The Perchloride of Copper may be analyzed exactly in the same way. 
1442. The Native Black Sulphuret of Copper (844), or Vitreous 
Copper Ore, should consist in theory of 
80 copper 
20 sulphur 
100 
In the following analysis of this ore by Klaproth (Essays, i. 542), 
there is a close approach to these numbers ; he probably lost a little 
sulphur by acidification, which might have been estimated by nitrate of 
baryta. 
a. Upon 200 grains of the ore, coarsely powdered, moderately 
strong nitric acid was abused, which attacked and dissolved them with 
frothing and extrication of red vapours. The solution was clear, and 
the sulphur alone in the ore was left behind, floating in the fluid, in 
grey loose flocculi, without any other residue, which indicated that no 
antimony was present. The sulphur collected on the filter was heated 
in a small crucible to inflammation, and it burned with its peculiar 
odour, without any trace of arsenic ; yet leaving a slight portion of 
oxided iron and siliceous earth. 
b. The solution, which had a pure blue colour, was treated first with 
muriate and then with sulphate of soda, but these produced no altera- 
tion, by which it appears that this ore contains neither silver nor lead. 
a. 200 grains of the powdered ore were heated with muriatic acid ; 
as this alone manifested no action, I added nitric acid by drops, which 
exerted a strong attack. When the solution of the ore had been ac- 
complished, I separated the fluid from the sulphur floating on the sur- 
face, and digested this last with a fresh quantity of muriatic acid, drop- 
ping into it some nitric acid ; after which I collected it upon the 
This sulphur, washed and desiccated, weighed grains, out oi 
which after its combustion 1> grain of siliceous earth remained; so 
that the true amount of sulphur was 37 grains. 
b. The solution exhibits a glass-green colour. I divided it into two 
parts. Into one half polished iron was immersed, upon which the ANALYSIS OF THE 
copper precipitated. It weighed 78| grains when washed, and desic- 
cated. 
c. In order to ascertain the proportion of iron contained in the ore, 
I combined the other half of the solution with caustic ammoniac added 
to excess. The iron remained behind, in the form of brown oxide, 
which, collected on the filter, desiccated and ignited, weighed three 
grains. But as the iron is contained in the mixture of the ore in the 
reguline metallic state, these 3 grains give 2| of metallic iron to be 
added in the computation. 
Therefore one hundred parts of the Siberian vitreous copper ore 
consist of 
Copper, b 
Iron,c 
Sulphur, a ..... . 
Silex, a 
100. 
The same method of analysis applies to the other sulphurets of cop- 
per or copper pyrites. 
1443. The Ferro-arsenical Sulphuret of Copper, (844), was analyz- 
ed as follows by Mr. R. Phillips.—Quarterly Journal of Science and 
Arts, vii. 100. 
a. Having ascertained that the constituents of this ore are copper, 
iron, arsenic, and sulphur, I boiled 100 grains of it reduced to powder 
in nitric acid, until the whole of the metallic matter appeared to be 
dissolved. 14 grains remained unacted upon by the acid ; of these a 
large portion was evidently pure sulphur ; by heat 9 grains were vo- 
latilized, and 5 remained, which were merely silica that had been me- 
chanically mixed with the ore. 
b. The nitric solution was decomposed by potash, and being heated 
with excess of it, peroxide of copper and iron were precipitated 
together. This mixed precipitate was washed until it ceased to be al- 
caline,and was then dissolved in nitric acid. To the solution ammonia 
in excess was added ; by this, peroxide of iron was precipitated, and 
the peroxide of copper held in solution ; the former being sepa- 
rated, washed, and ignited, weighed 13.3 grains, equivalent to 9.26 of 
iron. 
c. The ammoniacal solution of copper was heated, and when the 
greater part of the ammonia was expelled, potash was added to the so- 
lution ; and, by continuing the heat, peroxide of copper was precipitat- 
ed, which being washed and ignited, weighed 56.6 grains, equivalent 
to 45.32 of copper. 
d. The alcaline solution obtained in c, and the water employed to 
wash the mixed precipitate of oxide of copper aud iron, were evapo- 
rated together, and then saturated with nitric acid. This solution con- 
tained the sulphur and arsenic converted into acids, and combined with 
potash. Nitrate of barytes being added, sulphate was precipitated, 
which, being washed and ignited, weighed 126 grains, equal, accord- 
ing to Dr. Wollaston’s scale, to 17.14 of sulphur, which, added to 9, 
before obtained, = 26.14. After this an accident happened to the so- 
lution, which prevented the separation of the arsenic acid ; therefore, PHOSPHATE OP COPPER. 
e. 100 grains of the ore were again treated with nitric acid ; with 
the silica 11 grains of sulphur were obtained, and the nitric solution 
was decomposed by excess of potash as before, in order to separate 
the oxide of copper and iron. 
f. The alcaline solution being saturated with nitric acid, nitrate of 
fearytes was added to it, as long as precipitation took place. The pre- 
cipitated sulphate of barytes being washed and ignited, weighed 150 
grains, = 20.4 sulphur, which added to 11, separated without acidify- 
ing, = 31.4 ; the mean quantity of this and the first experiment being 
28.74. 
g. To the solution from which the sulphuric acid had been separat- 
ed by nitrate of barytes, nitrate of lead was added as long as arseni- 
ate of lead was thrown down ; and this, when washed and ignited, 
weighed 53 grains. 
According to Dr. Thomson, 21.25 of arseniate of lead contain 7.5 of 
arsenic acid, equivalent to 4.75 of arsenic ; if then, 21.25 give 4.75 ; 
53 of arseniate of lead will indicate 11.84 of arsenic. It appears 
from these experiments, that this ore consists of nearly 
Silica 
Iron 
9.26 
Copper 
45.32 
Sulphur 
28.74 
Arsenic 
11.84 
100.16 
In performing this analysis, some circumstances occurred which I 
think worthy of notice. In a preliminary experiment, I endeavoured 
to separate the copper from the iron by means of ammonia, without 
previously separating the arsenic acid ; this I found impracticable, for 
it appeared that the arseniate of iron, at first precipitated, was even- 
tually dissolved by the ammonia. In some treatises on chemistry, the 
arseniate of barytes is described as an insoluble salt: this, as may be 
deduced from what I have stated, is not the case. I first tried it by 
pouring a solution of arseniate of potash in o one of nitrate of ba- 
rytes ; no precipitation occurred, but, upon standing some days, very 
delicate feathery crystals of arseniate of barytes were formed, which 
exhibited the prismatic colours with a splendour equal to that of the 
noble opal. I have since attempted, but without success, to reproduce 
the salt having this appearance*. 
1444. Native Phosphate of Copper was analyzed by Klaproth nearly 
as follows : The ore was digested in nitric acid, by which it was en- 
tirely dissolved, with the exception of a remnant of silica. The ni- 
tric solution was divided into two parts ; the phosphoric acid was pre- 
cipitated from one, in the state of phosphate of lead, by adding acetate 
of lead ; and from the weight of the phosphate of lead, the quantity of 
phosphoric acid was calculated. The other half of the solution was 
* In paragraph 1031, it is stated, thatwhen neutral arseniate of potassa is added to nitrate 
of baryta an insoluble arseniate of baryta is thrown down, but if the binarseniate of potassa 
(1028) be used, the appearances arc as above-described by Mr. Phillips, unless, the solutions 
be very concentrated, in which case arseniate of baryta is presently thrown down, 366 
acted upon by iron to throw down the copper. He concluded from 
these experiments that the ore contained 
AX'ALYSKS OF THE 
68.13 oxide of copper 
30.95 phosphoric acid 
99.08 
It does not however seem clear whether the native phosphate of 
copper is a subphosphate of the peroxide, or a neutral phosphate of 
the protoxide ; that is, whether it consists of 80 peroxide + 28 phos- 
phoric acid; or of 72 protoxide -f- 28 phosphoric acid, these com- 
pounds requiring further investigation. 
1445. Native Carbonates of Copper.—These, as well as the artifi- 
cial carbonates have been analyzed by Mr. R. Phillips (Quarterly Jour- 
nal of Science and Arts, iv. 274), and the results are given above, 
(857, fyc.) The following is the process which he employed : 
200 grains of green carbonate of copper heated to redness in a pla- 
tinum crucible, became perfectly black, and lost 55.6 grains. 
I put some nitric acid into a small phial, the stopper of which had 
been perforated, and a glass tube passed through it, to suffer the escape 
of the carbonic acid gas ; the weight of the phial and acid being taken, 
I gradually put into it 200 grains of green carbonate of copper in small 
fragments. When the solution was complete, I found that 37 grains of 
carbonic acid had been evolved. If then from 200 we subtract 55.6, 
the loss by heat, we have 144.4 as the quantity of peroxide of cop- 
per ; and if from 55.6 we take 37, the carbonic acid, there remain 18.6 
as the proportion of water dissipated by heat. 100 parts of green car- 
bonate of copper consist therefore of 
Peroxide of Copper . . . . 
. . . . 72.2 
Carbonic acid 
Water 
. . . 9.3 
100.0 
On examining the solution I found it to be pure nitrate of copper. 
1446. The following comparative results will show how near in this 
instance experiment agrees with theory, if we regard the green carbo- 
nate of copper, or malachite, as consisting of 1 proportional of perox- 
ide of copper, 1 of carbonic acid, and 1 of water; or as an hydrated 
subcarbonate. 
Peroxide of copper . 
Vauqnelio. 
. . 70.10 
Phillips. 
72.2 
Theory. 
72.01 
Carbonic acid .... 
. . 21.25 
18.5 
19.82 
Water 
9.3 
8.17 
100.00 
100.0 
100.00 
1447. Assay of Copper Ores.—When the ores contain sulphur and 
arsenic, they are roasted till fumes no longer arise, or reduced to pow- 
der and deflagrated with nitre. The residue is mixed with black flux 
(1012), and exposed for one hour to a bright red heat in a wind-fur- 
nace, when a button of copper is formed at the bottom of the cruci- 
ble, the purity of which may be judged of by its appearance and 
malleability. COMBINATIONS OF LEAD. 
367 
The oxides and carbonates of copper are reduced by simple fusion 
with black flux, care being taken to raise the heat sufficiently. 
Section XIV. Of the Combinations of Lead. 
1448. Lead constitutes a component part of several complex ores', 
the analyses of which are described in the sections on antimony and 
silver. 
1449. Galena or Sulphuret of Lead (885) may be analyzed by the 
action of dilute nitric acid, which dissolves the lead and separates the 
sulphur : the lead may be precipitated by sulphate of soda : 100 grains 
of the sulphate of lead thus thrown down, after having been dried at 
a dull red heat, are equivalent to 69 of lead. 
1450 Vauquelin analyzed a galena from Cologne, as follows. (Jour- 
nal des Mines, No. 68.) It was heated with very dilute nitric acid; 
the undissolved residue, consisting of silica and sulphur, was heated 
to redness, by which the latter was dissipated, and pure silica remain- 
ed. The nitric solution was decomposed by sulphate of soda, and the 
sulphate of lead collected, dried, and weighed, to estimate the propor- 
tion of metal. The remaining liquor being saturated by ammonia, 
gave a precipitate of oxide of iron ; and lastly, carbonate of ammonia, 
threw down carbonate of lime. 
1451. A native Sulphate of Lead from Anglesea (889) was thus ana- 
lyzed by Klaproth : 100 grains moderately heated lost 2 of water; the 
remainder was fused in a platinum crucible with four parts of carbon- 
ate of potassa, which gave a yellow hard mass partly soluble in water; 
the insoluble residue when dry was 72 grains of oxide of lead ; it was 
dissolved in nitric acid, and this solution gave, when decomposed by 
the immersion of a rod of zinc, 66.8 grains of metallic lead. The 
alcaline solution from the crucible was saturated with nitric acid, and 
acetate of baryta added as long as it occasioned a precipitate, which 
weighed when quite dry 73 grains, equal to 25 of sulphuric acid. 
Hence it appears that this ore contains 
66.5 lead j 
5,5 oxveen 
| = 72 oxide of lead 
25 sulphuric acid 
97 
Loss, consisting of 1 gr.) 
of oxide of iron, and 2 \ 
3 
of water ) 
100. 
1452. Native Phosphate of Lead (896) was also examined by Kla- 
proth ; it is a distinctive character of this compound, that when fused 
into a globule before the blow-pipe, it assumes, as it cools, a dodecae- 
dral form. 100 grains of green prismatic phosphate of lead dissolved 
entirely in nitric acid. Nitrate of silver gave a precipitate of !1 grains of chloride = 2.7 of chlorine. Sulphuric acid added to the 
warm solution gave 106 of sulphate of lead = 78.4 of oxide of lead : 
the liquor was then freed from excess of sulphuric acid by nitrate of 
baryta, and after having been nearly saturated by ammonia, acetate of 
lead was added ; the phosphate of lead thus precipitated weighed 82 
grains = 18.37 of phosphoric acid (more correctly 16.5). In the re- 
siduary solution was found a trace of iron. 
1453. Native Carbonate of Lead (898) may be thus analyzed. 
Reduce the ore to powder and introduce 100 grains into a sufficient 
quantity of nitric acid diluted with about two parts of water ; an ef- 
fervescence ensues, and the carbonic acid may be estimated by loss of 
weight; it amounted to 16 grains. Filter the nitric solution, and if 
there be any insoluble residue, it is probably silica ; to the filtered li- 
quor add sulphate of soda, which throws down sulphate of lead, 
whence the oxide may be deduced ; or immerse a plate of zinc into 
the nitric solution, which throws down metallic lead : in Klaproth’s an- 
alysis he thus obtained 77 of metal equivalent to 82.5 oxide; whence 
it appears that the native carbonate contains 
ANALYSES OP THE 
16. carbonic acid 
82.5 oxide of lead 
98.5 
These numbers almost exactly agree with the theoretical composition 
of the carbonate of lead ; the loss amounting to 1.5 may probably be 
considered as 0.5 carbonic acid and 1. water. 
1454. The Murio-Carbonate of Lead, or Native Muriate of Lead 
(877), as it is generally called, was analyzed as follows, by Mr. Chene- 
vix. (Nicholson’s Journal, 4to. iv.) 100 grains, dissolved in nitric 
acid, lost 6 of carbonic acid; the nitric solution was neutralized by 
ammonia, and the absence of arsenic, phosphoric, and sulphuric acids 
proved by tests. Nitrate of silver was then added, which formed a 
copious precipitate, weighing when dry 48 grains, equivalent, accord- 
ing to Mr. Chenevix, to 8 of muriatic acid; he concludes that the 6 
grains of carbonic acid saturated 34 of oxide of lead, and that 8 of 
muriatic acid saturated 51 of oxide of lead ; and therefore, that the 
ore consists of 59 muriate of lead and 40 carbonate of lead. 
Klaproth’s analysis agrees almost exactly with that of Mr. Chene- 
vix, and they give the following view of the composition of this ore, 
but there is probably some considerable error in the estimate of the 
muriatic acid, and a new analysis is highly desirable. 
Oxide of lead .... 
Carbonic acid .... 
6. 
Muriatic acid .... 
8.5 
100.0 
1455. la the assay of lead ores by fire, a considerable loss is often 
sustained by the volatilization of the oxide of lead, and by its action 
upon the crucible, so that the operation is best performed by humid 
analysis ; the ore may be digested in dilute nitric acid, and to the solu- 
tion. when filtered, sulphate of soda may be added, which will throw SVLPHURETS OP ANTIMONY. 
down sulphate of lead ; the latter, when washed and dried at a red 
Meat contains about 68 per cent, of the metal. 
Section XV. Of the Combinations of Antimony. 
1456. There are three proper ores of antimony, Native Antimony 
(905), Native Oxide of Antimony (912), and the Native Sulphuret (905). 
1457. Native antimony from Andreasberg was examined as follows 
by Klaproth (Essays, ii. 136.) 100 grains in powder were heated with 
nitric acid, the mixture diluted with water and filtered ; muriatic acid, 
added to the filtered liquor, gave a precipitate of chloride = 1 grain of 
metallic silver; and the residual liquor gave oxide of iron = .25 grain 
of metallic iron. The oxide of antimony upon the filter was perfectly 
soluble in muriatic acid ; a piece of zinc, immersed in this muriatic 
solution, gave 98 grains of metallic antimony; hence the components 
are Antimony 98. 
Silver 1. 
Iron 0.25 
99.25 
1458. The Native Oxide, or white ore of Antimony from Pritzbram, 
in Bohemia, was also analyzed by Klaproth ; he found it a perfectly 
pure oxide, but did not ascertain the relative proportions of its compo- 
nent parts. According to Vauquelin, it contains silica and a little oxide 
of iron.—Hauy, iv. 274. 
1459. The following is the analysis of an iridescent sulphuret of 
antimony, in acicular crystals, from Hungary. 
a. 100 grains digested in two parts of nitric acid and one of water 
afforded a portion of sulphur, which, having been carefully separated 
from the adhering oxide, burned entirely away. It weighed 17.5 grains. 
h. The insoluble oxide collected and washed, was re-dissolved in 
muriatic acid, and zinc immersed into the solution, by which 74 grains 
of metallic antimony were thrown down. 
c. The nitric solution being evaporated to one-fourth, let fall a por- 
tion of white powder, which, treated as b, gave 2 grains of antimony. 
d. The solution c appearing now to be free from antimony, was di- 
luted and divided into two equal portions, a and b. Muriate of baryta, 
added to a, gave a precipitate of sulphate of baryta, weighing 22.5 
grains, = about 3 grains of sulphur, or 6 in 100. 
e. The portion b tested by muriate of soda gave no indication of sil- 
ver ; supersaturated with ammonia, it let fall 1.5 grains of peroxide ®f 
iron, to about 1 grain of iron. 
f The results of this analysis, therefore, are 
Sulphur . . . 
{ a. 
• 1 d. 
20.5 
6. 
grs. | 
23.5 grs 
Antimony . . 
( b. 
’ ( c’ 
74. 
2. 
grs. | 
76.0 
Iron 
2. 
101.5 ANALYSES OF THE TRIPLE SULPIIURET 
The small increase of weight I refer to zinc adhering to the antimony. 
1460. The red ore of Antimony, from Braunsdorff in Saxony, was an- 
alyzed by Klaproth ; he digested it in muriatic acid, and threw down 
the antimony by water and potassa ; the precipitate, after a second so- 
lution and precipitation, was re-dissolved in muriatic acid, and decom- 
posed by a piece of polished iron, which caused the separation of 67.5 
grains of metallic antimony. The sulphur he estimates at 19.70 per 
cent., and attributes the loss of weight to oxygen combined with the 
antimony ; he therefore regards the Ore as a sulphuretted oxide of an- 
timony, containing 
Antimony 
67.50 
Oxygen 
Sulphur 
98. 
1461. The following is Mr. Hatchett’s instructive analysis of Bour- 
nonite, or the triple sulphuret of Lead, Antimony, and Copper: 
a. 200 grains of the ore, reduced to a fine powder, were put into a 
glass matrass, and, two ounces of muriatic acid being added, the vessel 
was placed in a sand-bath. As this acid, even when heated, scarcely 
produced any effect, some nitric acid was gradually added, by drops, 
until a moderate effervescence began to appear. 
The whole was then digested in a gentle heat, during one hour ; and 
a green-coloured solution was formed whilst a quantity of sulphur float- 
ed on the surface, which was collected, and was again digested in ano- 
ther vessel, with half an ounce of muriatic acid. 
The sulphur then appeared to be pure, and, being well washed and 
dried on bibulous paper, weighed 34 grains : it was afterwards burned 
in a porcelain cup, without leaving any other residuum than a slight 
dark stain. 
b. The green solution, by cooling, had deposited a white saline se- 
dime»t; but this disappeared upon the application of heat, and the ad- 
dition of the muriatic acid in which the sulphur had been digested. 
The solution wTas perfectly transparent, and of a yellowish green : 
it was made to boil, and in this state was added to three quarts of boiling 
distilled water, which immediately became like milk ; this was poured 
on a very bibulous filter, so that the liquor passed through before it 
had time to cool ; and the white precipitate thus collected, being well 
edulcorated with boiling water, and dried on a sand-bath, weighed 63 
grains. 
c. The washings were added to the filtrated liquor; and the whole 
was gradually evaporated at different times, between each of which it 
was suffered to cool, and remain undisturbed during several hours. A 
quantity of crystallized muriate of lead was thus obtained, until nearly 
the whole of the liquor was evaporated : to this last portion a few drops 
of sulphuric acid were added, and the evaporation was carried on to 
dryness ; after which the residuum, being dissolved in boiling distilled 
water, left a small portion of sulphate of lead. 
The crystallized muriate of lead was then dissolved in boiling water ; 
and, being precipitated by sulphate of soda, was added to the former 
portion, was washed, dried on a sand-bath, and then weighed 120.20 
grains. of lead, antimony, and copper. 
j>. The filtrated liquor was now of a pale bluish-green, which changed 
to deep blue, upon the addition of ammonia ; some ochraceous flocculi 
were collected, and, when dry, were heated with wax in a porcelain 
crucible, by which they became completely attractable by the magnet, 
and weighed 2.40 grains. 
e. The clear blue liquor was evaporated nearly to dryness ; and, 
being boiled with strong lixivium of pure potash, until the whole was 
almost reduced to a dry mass, it was digested in boiling distilled water ; 
and the black oxide of copper, being collected and washed on a filter, 
was completely dried, and weighed 32 grains. 
200 grains of the ore, treated as here stated, afforded, 
Crraina. 
a. Sulphur 
34. 
b. Oxide of antimony. . . 
G3. 
c. Sulphate of lead . . . . 
120.20 
d. Iron 
2.40 
e. Black oxide of copper 
32. 
But the metals composing this triple sulphuret are evidently in the 
metallic state ; and white oxide of antimony precipitated from muriatic 
acid by water, is to metallic antimony as 130 to 100 ; therefore, the 
63 grains of the oxide must be estimated at 48.46 grains of the metal. 
Again, sulphate of lead is to metallic lead as 141 to 100 ; therefore, 
120.20 grains of the former are — 85 24 grains of the latter. And, 
lastly, black oxide of copper contains 20 per cent, of oxygen ; conse- 
quently, 32 grains of the black oxide are = 25.60 grains of metallic 
copper. 
The proportions for 200 grains of the ore, will therefore be, 
Sulphur ...... 
Antimony 
Lead 
Iron 
Copper 
195.70 
Loss .... 
1462. The principal ores of bismuth are, Native Bismuth, the Sul- 
phuret, the plumbo-cxip riferous Sulphuret, and the Native Oxide. Kla- 
proth’s analysis of the bismuthic silver ore will be found in a follow- 
ing Section. 
1463. The Sulphuret of Bismuth has been analyzed by Sage (Mem 
de V Acad, des Scien., 1782, p. 307.) but the following more complicat- 
ed analysis of one of the ores of this metal renders it unnecessary to 
advert to other details. 
Section XVI. Of the Combinations of Bismuth. ANALYSES OF THE 
1464. The needle ore of Siberia, ox Sulphuret of Lead, Copper, and 
Bismuth, was examined as follows : 
a. 50 grains, separated as far as possible from its quartzose matrix, 
were digested in nitric acid diluted with its bulk of water ; when all 
action had ceased, a gentle heat was applied for a few hours, until no 
further action took place. The whole was then poured upon a filter, 
and the residue being washed and dried, weighed 8.8 grains ; it was 
burned, and there remained upon the capsule 2.3 grains of silica ; the 
burned portion, amounting to 6.5 grains, being considered as sulphur. 
There was also an inappreciable portion of sulphate of lead. 
b. The filtered solution being evaporated, let fall crystals of nitrate 
of lead ; the evaporation was carried nearly to dryness, and the resi- 
due, put into 8 ounces of water, deposited a quantity of oxide of bis- 
muth, which being collected, washed, and dried, weighed 20 grains. 
On evaporating the filtered liquor to half its bulk, there was a further 
deposit of 3 grains of oxide of bismuth. Now, 23 grains of oxide of 
bismuth may be computed as equal to 20.5 of the metal. 
c. The evaporation was now carried nearly to dryness, a portion of 
excess of acid driven off, and the residue again diluted, by which a very 
slight turbidness was produced, but no appreciable portion of bismu- 
tliic oxide deposited. I therefore poured sulphate of soda into the so- 
lution, and the precipitate of sulphate of lead thus formed, weighed, 
when dry, 18.5 grains, equivalent to about 12.7 of lead. 
d. The filtered liquor was now evaporated to dryness, and the resi- 
due dissolved in a small quantity of water ; carbonate of soda was added, 
and the blue precipitate being collected and washed, was digested 
in ammonia, in which it was totally soluble ; the ammonia being driven 
off, the residue was heated red-hot, and had the properties of pure 
peroxide of copper ; it weighed 8 grains, which is nearly equivalent to 
6.5 of copper. 
These were all the components of this triple sulphuret which I could 
separate, though, from its odour before the blow-pipe, I suspect the 
existence of a trace of arsenic in it: the following, therefore, are the 
results of the analysis :— 
Sulphur (a) 
Bismuth (6) 
20.5 
Lead (c) 
Copper(d) 
46.2 
Silica (a) 
Loss 
50.0 
t rom the small quantity of the needle ore in my possession, I could 
not repeat this analysis, nor could I employ separate portions for the 
separation of its several components. 
Dr. John (Chemische Untersuchungen, p. 216.) whose analysis is, I 
believe, the only one previously published, gives the following as the 
composition ol this ore of bismuth: COMBINATIONS OF COBALT 
Bismuth.... 
. . . 43.20 
. . . . 21.60 
Lead 
. . . . 12.16 
Copper .... 
. . . 12.10 
. . . . 6.05 
Sulphur .... 
. . . 11.58 
. . . . 5.79 
Nickel .... 
. . . 1.58 
. . . . 0.79 
Tellurium. . . 
. . . 1.32 
. . . . 0.66 
Gold 
. . . 0.79 
. . . . 0.39 
94.89 
47.44 
Loss .... 
. . . 5.11 
. . . . 2.56 
100 
50.00 
It may be observed, that in both these analyses, but especially in 
the latter, the proportion of sulphur falls short of that required to 
constitute the respective sulphurets of lead, copper, and bismuth, and 
that the loss therefore may be most plausibly ascribed to sulphur. 
1465. The Native Oxide of Bismuth consists, according to Lampa- 
dius, of 
Oxide of bismuth 
.... 86.3 
Oxide of Iron 
.... 5.2 
Carbonic acid 
Water 
Heat would expel both the water and carbonic acid from this com- 
pound : the relative proportion of the latter might be learned by the 
loss of weight during effervescence. The ore might then he dissolved 
in the smallest possible quantity of nitric acid, and excess of ammonia 
would precipitate the peroxide of iron, but retain the bismuth in so- 
lution ; the oxide of bismuth might then be obtained by evaporation to 
dryness, and exposure to heat sufficient to decompose the nitrate of 
ammonia. 
Section XVII. Of the Combinations of Cobalt. 
1466. The analyses of the chloride and of the sulphate of cohalt 
are given in Section XVII. of the preceding Chapter, (paragraphs 960 
and 969.) from which the equivalent of the metal is deduced. 
The principal difficulties that occur in examining the combinations of 
cobalt are, its separation from arsenic, from nickel, and from copper, 
which may be performed as follows. 
a. 100 grains of an alloy of cobalt, arsenic, nickel, and copper, are 
digested in nitric acid till perfectly dissolved; the solution is then eva- 
porated to dryness, and a fresh portion of nitric acid distilled off the. 
dry salt, in order to ensure the complete acidification of the arsenic ; 
the residue, consisting of arseniates of cobalt, copper, and nickel, may 
then be treated by nitrate of lead, which will remove the arsenic acid 
in the form of insoluble arseniate of lead; but a more convenient 
method of proceeding is perhaps as follows: boil the arseniates re- 
peatedly in solution of potassa, until that alcali no longer takes up ANALYSES OF THE 
arsenic acid ; the oxides of cobalt, nickel, and copper, will thus be 
obtained nearly, if not quite, free from arsenic acid. 
b. To separate the oxides of copper, cobalt, and nickel, dissolve 
them (in the state of hydrates) in dilute nitric acid, and immerse a plate 
of iron, which will throw down metallic copper, and a mixed nitrate 
•of iron, cobalt, and nickel, will be obtained. 
c. To this mixed nitrate add potassa, wash the precipitate, and digest 
it in ammonia, which will take up the oxides of cobalt and nickel, 
leaving the peroxide of iron. 
d. The ammoniated solution of cobalt and nickel may be treated as 
directed by Mr. R. Phillips, {Phil. Magazine, xvi. 313.) Evaporate 
it till the excess cf ammonia is expelled (which is known by no change 
of colour being produced by it on turmeric paper), and then add solu- 
tion of potassa, and dilute considerably ; the oxide of nickel instantly 
falls, but that of cobalt remains some time in solution, and may be ob- 
tained by neutralizing the alcaline liquor. 
1467. The following is Tassaert’s analysis of the Arsenical Coball, 
er white cobalt glance of Tunneberg. 
That the reader may better understand the process, it may be pre- 
mised, that when reguline arsenic is boiled with a little nitric acid, it is 
dissolved and converted into white oxide, all of which is deposited by 
mere evaporation to a small bulk of liquid ; but when much nitric acid 
is used, the arsenic is more or less acidified, becomes thereby much, 
more soluble in water, and then acting as an acid, it readily dissolves 
cobalt, iron, fyc., forming arseniates of those metals, which are decom- 
posable by the fixed alcalis. It may be also added, that oxide of cobalt 
is soluble in ammonia, but oxide of iron is not; and that the nitrate of 
iron deposits much of its iron by mere exposure to air, but the nitrate- 
of cobalt remains clear. 
a. To estimate the quantity of arsenic separately, M. Tassaert di- 
gested 100 parts of the cobalt ore with dilute nitric acid, and in some 
hours the whole was dissolved, but by cooling deposited a quantity of 
white crystalline grains. On evaporation, more of them were depo- 
sited, and when all had thus separated, they were collected and dried, 
and weighed 56 parts, all of which was sublimed by heat except 3 parts, 
probably a mixture of arsenic and cobalt. Hence the oxide of arsenic 
from this ore may be reckoned at about 53 parts, indicating 49 per cent. 
of metallic arsenic in the ore. 
b. 300 parts of the ore were then digested with four times as much 
nitric acid, which made a rose-coloured solution. By partial evapora- 
tion, adding water, and heating, a rose-white precipitate (a) fell down, 
leaving a rose-coloured solution. This solution, boiled with an excess 
of potash, gave an oxide of cobalt, at first rose-coloured, then passing 
to green, and, when dried in a red heat, black. It weighed 85 parts. 
c. The 85 parts of the last experiment were then examined for iron. 
When re-dissolved in nitro-muriatic acid, pure ammonia was added, 
which gave a black precipitate, which was all re-dissolved by an excess 
of the alcali except a small portion, which, again treated with nitro- 
muriatic acid and ammonia, was reduced to 4 parts, and appeared to be 
oxide of iron. 
d. The rose-precipitate of experiment b, which proved to be a 
mixed arseniate of cobalt and iron, was decomposed by caustic potash 
in excels, and gave a precipitate weighing 100 parts when dried. e. The 100 parts of the last experiment were re-dissolved in nitric 
acid, the solution evaporated partly, and then diluted with water ; a 
precipitate of oxide of iron weighing 27 parts then separated, and a 
clear solution of cobalt was left. 
f. The nitrate of cobalt of the last experiment was decomposed by 
ammonia, and the precipitate re-dissolved by an excess of the alcali, 
except 15 parts of insoluble oxide of iron : the solution was added to 
the ammoniated cobalt of experiment c. 
g. The insoluble precipitates of oxide of iron of c, e, and f, were 
then mixed and examined: they still gave a blue glass with borax, and 
therefore contained a certain portion of cobalt. Acetic acid was found 
a good method of separating them : for this purpose they were re-dis- 
solved in nitro-muriatic acid, precipitated by just sufficient ammonia, 
and the precipitate wffiilst still wet was put into acetic acid. This dis- 
solved the whole at first, but on boiling and evaporating the solution 
nearly to dryness, most of the iron separated, and by re-dissolving 
in water and evaporating nearly to dryness successively four times, 
nearly all the oxide of iron was rendered insoluble, whilst the cobalt 
remained in the solution, and this acetited cobalt in proportion as it was 
freed from iron became more and more of a fine rose colour. This 
last was then supersaturated with ammonia, and the solution of ammo- 
niated cobalt was added to the different portions of the same obtained 
in the former experiments. The whole was then boiled to expel the 
excess of ammonia, and by adding potash the whole of the pure oxide 
was precipitated, which when well washed and dried, weighed 133 
parts. This oxide reduced in a crucible lined with charcoal, gave 
regulus of cobalt in its purest form, of the specific gravity of 8.5S8, 
and to all appearance totally free from arsenic and iron. 
h. Lastly, to estimate the quantity of sulphur, 100 parts of the ore 
were separately boiled with 500 of nitric acid, and diluted with water, 
to separate all the oxide of arsenic that would be deposited spontane- 
ously. All the sulphur being now converted into sulphuric acid by the 
action of the nitric acid, nitrate of barytes was added, and from the 
precipitated sulphate of barytes, the quantity of sulphuric acid, and of 
course, of sulphur, was estimated according to known proportions, 
-—Aikin’s Dictionary, i. 307. 
COMBINATIONS OF VJRANIWM. 
Section XVIII. Of the Combinations of Uranium. 
1468. In Section XVIII. of the preceding Chapter, the Pechblende 
of mineralogists is erroneously represented as a Native Sulphuret of 
Uranium ; it is, however an oxide of uranium, combined with a little 
oxide of iron, sulphuret of lead, and silica ; probably accidental ingre- 
dients, as shown by the following results of Klaproth’s analysis of the 
pitch ore of uranium, from Joachimsthal: 
Oxide of uranium . . . 
. . . 86.5 
Oxide of iron 
... 2.5 
Sulphuret of lead . . . 
... 6.0 
Silica . . . 
... 5.0 
100. ANALYSES OF THE 
1469. The following is a general process for the analysis of uranitie 
ores. 
a. Digest in dilute nitric acid, which separates sulphur and silica (if 
sufficiently dilute without the acidification of the former) ; burn off 
the sulphur, and the silica remains. 
b. To the nitric solution add sulphate of soda, which separates lead 
in the state of sulphate. 
c. To the remaining solution add liquid potassa in excess, and boil; 
filter, wash the precipitate, and digest it in pure ammonia which takes 
up the copper, and which may be obtained by immersing a plate of 
zinc in the ammoniacal solution slightly supersaturated with sulphuric 
acid. 
d. Digest the portion of the precipitate c, insoluble in ammonia, in 
bi-carbonate of potassa, which, if used in sufficient quantity, takes up 
oxide of uranium, leaving oxide of iron. 
1470. The Micaceous Uranite, from the Gunnis Lake mine in Corn- 
wall was analyzed as follows, by Mr. Gregor (Annales of Philosophy, r. 
281.) : 
a. 100 grains lost, by exposure to a low red heat, 15.4 grains of 
water. 
b. 100 grains (not previously ignited), repeatedly boiled in excess 
of nitric acid, left a residue amounting only to 0.1 grain of silica and 
oxide of iron. 
c. Excess of ammonia added to the nitric solution, threw down a 
yellow precipitate, which, digested in excess of ammonia, gave a blue 
solution, and left 74.9 grains of oxide of uranium, not quite pure. 
d. The ammoniacal solutions were evaporated to dryness, and the 
residue again digested in ammonia left 0.2 grains of oxide of uranium. 
The ammoniacal solution again evaporated, and the residue dissolved 
in nitric acid, gave with potassa a precipitate, which dried and ignited, 
was 7.65 grains of oxide of copper. 
e The 74.9 grains of oxide c, digested in dilute sulphuric acid, left a 
trace of lead. The sulphuric solution, precipitated by excess of am- 
monia, still showed traces of copper, and by a cylinder of zinc gave 
0.5 grain of metallic copper = 0.62 of oxide ; so that the 74.9 grains 
of process c were reduced to 74.28, to which add the 0.2 grain of 
process d, and it gives the whole amount of oxide of uranium =» 
74.48. The results of the above analysis are 
Oxide of uranium, with a > 
74.48 
trace of lead $ 
Oxide of copper, d e . . 
8.20 
Water 
15.40 
98.08 
Loss 
1.92 
100.00 COMBINATIONS of cerium. 
Section XIX. Of the Combinations of Titanium. 
1476. Klaproth and Vauquelin have furnished analyses of the ti- 
tanic ores, of which the following examples will suffice 
The silico-calcareotis titanite from Bavaria was thus analyzed by Kla- 
proth (Essays, i. 214.) : 
a. 100 grains in line powder were ignited for an hour with 400 grains 
of caustic potassa, and the resulting mass digested in muriatic acid left 
12 grains of silica. 
b. Carbonate of potassa was added to the muriatic solution, and the 
precipitate thus obtained, being again digested in muriatic acid, left 23 
grains of silica. 
c. Caustic ammonia was then added to the preceding solution, and 
the precipitate dried and ignited gave 33 grains of oxide of titanium. 
d. To the remaining fluid, Avhilst boiling, carbonate of potassa was 
added, and the precipitate having been duly ignited, gave 33 grains of 
lime. 
The following then are the component parts of this mineral: 
Silica, a b 
Oxide of titanium, c . . 
. . 33 
Lime, d 
. . 33 
101 
1472. The following is Vauquelin’s analysis of the Menachanite of 
Bavaria (Journal des Alines, No. 19.) : 
a. 100 grains finely pulverized were fused for an hour and a half 
in a silver crucible, with 400 grains of potassa ; the fused mass, di- 
gested in water, left 124 grains of red insoluble powder. 
b. The 124 grains were boiled with potassa, and the solution, after 
saturation with muriatic acid, was treated with carbonate of potassa, 
which threw down 3 grains of oxide of titanium. 
c. The residue of the 124 grains was digested with dilute mui'iatic 
acid, which left 46 grains of oxide of titanium. 
d. The muriatic solution, saturated by ammonia, gave 50 grains of 
oxide of iron. 
e. The alcaline solution a, which was of a green colour, was super- 
saturated by muriatic acid, and evaporated to dryness ; the dry residue 
contained no silica, for it dissolved entirely in water ; on the addition 
©f carbonate of potassa, it yielded 2 grains of carbonate of manganese. 
Section XX. Of the Combinations of Cerium. 
1473. Cerite (997) was analyzed, with the following results, by Vau- 
quelin (Annales du Museum, v. 412.) : 
67 
oxide of cerium 
17 
silica 
2 
oxide of iron 
2 
lime 
12 
water and carbonic acid 
100 ANALYSES OF THE 
The following directions for the analysis of this ore are given by 
Messrs. Aikin : 
a. Having minutely pulverized the ore, weigh it, then ignite it and 
weigh it again ; the difference may be set down as the amount of wa- 
ter. 
b. Digest the calcined ore in repeated portions of nitro-muriatic 
acid, and when nothing further is taken up, fuse the residue with caus- 
tic potash ; then dissolve out the mass by muriatic acid, evaporate to 
dryness, and digest again in very dilute muriatic acid ; the insoluble 
residue is silex. 
c. Add together the muriatic and nitro-muriatic solutions, and de- 
compose the whole at a boiling heat by saturated carbonate of potash ; 
re-dissolve the whole in as little muriatic acid as possible, heat the so- 
lution to drive off the last remains of carbonic acid, and add perfectly 
caustic ammonia till there is an evident excess ; separate the precipi- 
tate, and add to the clear liquor as much muriatic acid as will saturate 
it, and then throw down from it the lime in the state of carbonate, by 
means of a mild alcali. 
d. The ammoniacal precipitate, consisting of the oxides of cerium 
and iron, is to be dissolved in muriatic acid, and liquid hydrosulphuret 
of potash is to be dropped in till the precipitate, which at first will be 
greenish, becomes white ; the clear liquor being separated and treated 
with carbonate of potash, affords a white precipitate, which is carbon- 
ate of cerium. 
e. The greenish precipitate is to be dissolved in as little muriatic 
acid as possible, and the solution being neutralized by an alcali to the 
point of precipitation, sulphate of soda is to be added, which will 
throw down a sulphate of cerium ; the residual fluid being then de- 
composed by ammonia, deposits oxide of iron. 
f. The sulphate of cerium e is now to be boiled with thrice its weight 
ef carbonated soda, by which it will be converted into carbonate, which 
is to be dissolved in dilute muriatic acid, and again precipitated by car- 
bonate of potash or of soda. 
g. The carbonates of cerium [d and/) are now to be calcined, b}' 
which the pure brown oxide of cerium will be obtained.—Addenda to 
the Dictionary, iii. 509. 
1474. Allanite, (997) analyzed by Dr. Thomson [Edinburgh Phil 
Trans., vi. 385.) was found to contain the following substances: 
Oxide of cerium 
. . . . 33.9 
Oxide of iron 
Silica 
35.4 
Lime 
Alumina 
4.1 
Water 
4.0 
112.0 
Section XXI. Of the Combinations of Tellurium, 
1475. The following is an outline of the analysis of several com- 
pounds of tellurium given by Klaproth, in his Chemical Examination 
of the Auriferous Ores of Transylvania, Essays ii. 1. QB.ES OF TELLURIUM. 
1476. Native Tellurium, from Fatzebay in Transylvania, contains, 
according to that celebrated analyst, 
92.55 
telluriuw 
7.20 
iron 
0.25 
gold 
100. 
The following method was pursued in the decomposition of this 
•are : 
a. It was separated as much as possible from its stony matrix and 
pulverized, was digested in six parts of warm muriatic acid, to which 
were added, cautiously and at intervals, three parts of nitric acid ; the 
compound acid acted violently on the ore, and took up the whole of it 
except the quartzose matrix. 
b. The acid solution being diluted with as much water as it would 
bear without decomposition, was combined with caustic potassa, upon 
which a copious precipitate fell down ; more alcali was then added, 
till the whole of the precipitate that was resoluble in this menstruum 
was taken up. There remained behind a dark-brown residue, con- 
sisting of the oxides of gold and iron. 
c The residue of b was then dissolved in nitro-muriatic acid, to 
which was afterwards added, drop by drop, nitrate of mercury, pre- 
pared in the cold, as long as the precipitate thus formed appear- 
ed of a brown colour ; this precipitate, consisting of gold and mu- 
riate of mercury, was then pretty strongly ignited in a crucible with 
borax, by which the mercury was driven off, and a button of pure gold 
remained. 
d. To the nitro-muriatic solution c, was now added caustic alcali, by 
which the oxide of iron was thrown down. 
e. The alcaline solution b was accurately saturated with muriatic 
acid, and then heated, by which a white heavy powder was obtained ; 
which, after being washed in a mixture of equal parts of alcohol and 
water, and then gently dried, was pure oxide of tellurium. 
1477. The grey ore of Tellurium, or Graphic Gold, of Offenbanya, 
contains 
60 tellurium 
30 gold 
10 silver. 
This ore was treated in the following manner : 
a. The finely pulverized ore was digested in nitro-muriatic acid till 
nothing more was taken up. 
b. The insoluble residue, consisting of quartz and muriate of sil- 
ver, was fused with five times its weight of carbonated soda* by which 
the silver was obtained in the metallic state. 
c. The nitro-muriatic solution being concentrated by evaporation, 
was largely diluted by alcohol, upon which the oxide of tellurium pre- 
cipitated ; and this being re-dissolved in muriatic acid, was obtained in 
black metallic flocculi, by means of a bar of polished iron. 
d. The nitro-muriatic solution c, after separation of the tellurium, ANALYSIS OF THE 
contained only gold, w hich was procured by the addition of a solution 
of green sulphate of iron. 
1478. The yellow ore of Tellurium, from Nagayag, is composed, ac- 
cording to Klaproth, of 
44.75 
tellurium 
26.75 
gold 
19.50 
lead 
8.50 
silver 
0.50 
sulphur 
100. 
He performed the analysis of this ore nearly as follows : 
a. 400 grains of the pulverized ore were digested with nitric acid* 
till every thing soluble in this fluid had been taken up. 
b. The nitrous solution was combined with muriatic acid, as long as 
any precipitation took place ; by this there was obtained 51 grains of 
a white powder, of which 43 grains were again resoluble in boiling 
water. The insoluble portion, amounting to 8 grains, was muriated 
silver. 
c. The solution, containing the 43 grains above-mentioned, was con- 
centrated by gradual evaporation, and afforded delicate needle-form- 
crystals of muriated lead. 
d. The residue of a, insoluble in nitric acid, was then treated with 
nitro-muriatic acid, as long as any thing was taken up; the solution 
was mixed with the nitro-muriatic solution b, and reduced by evapora- 
tion till it ceased to deposit muriate of lead. 11 grains were thus ob- 
tained. 
e. To the concentrated solution d, was added caustic potash in ex- 
cess, which threw down a copious blackish-brown precipitate ; this be- 
ing separated, the alcaline liquor was saturated with muriatic acid, and 
the white precipitate thus obtained, being again dissolved in muriatic 
acid, and then precipitated by means of a stick of zinc, afforded 85 
grains of metallic tellurium. 
f. The blackish-browrn precipitate of e was dissolved in nitro-muria- 
tic acid, and the liquor was nearly saturated with caustic potash ; nitrat- 
ed mercury was then added, till the precipitate began to be white ; 
this precipitate being separated by the filter, and washed, the filter, 
with its contents, was ignited in a crucible, and a little nitre being add- 
ed, the fire was increased, and a button of pure gold was thus obtained, 
weighing 50.75 grains. 
g. The remainder of the nitro-muriatic solution f was saturated 
with carbonated potash, and a precipitate was obtained, consisting of 
oxide of manganese, mixed with carbonated lime, and a little alumine 
and oxide of iron. 
h. The insoluble residue of d, weighing 120.5 grains, and consisting 
chiefly of quartz, was gently heated, by which it lost about 1 grain, 
which was sulphur ; being then mixed with four times its weight of 
carbonated potash, and fused, there was obtained a button of silver, 
weighing 10.125 grains. 
1479. The black ore of Tellurium, also from Nagavag, according to 
the same analyst consists of BLACK ORE OP TELLURIUM. 
54.0 
lead 
39.2 
tellurium 
9.0 
gold 
0.5 
silver 
1.3 
copper 
3.0 
sulphur 
100.0 
This ore was analyzed in the following manner : 
а. 1000 grains of the pulverized ore were digested with 10 ounce* 
of muriatic acid, to which was added, by degrees, a little nitric acid ; 
this being poured off, 5 ounces more of muriatic acid were added, 
by which every thing soluble in this menstruum was taken up ; to the 
filtered solution boiling water was added, to re-dissolve the muriate 
of lead which had begun to be deposited. 
б. Of the insoluble residue a part had cohered into a mass, and was 
for the most part sulphur, weighing 17.5 grains ; being gently ignited, 
it left behind 3.5 grains of a blackish matter, which was dissolved in 
muriatic acid, and added to the foregoing solution. Hence the sulphur 
of the ore amounted to 14 grains. 
c. The remainder of the insoluble residue was for the most part 
quartz, and weighed 440.5 grains. Being melted with four times its 
weight of carbonated potash there appeared, on breaking the mass, a 
few globules of silver, amounting to about 2.5 grains equivalent to 3.5 
grains of muriated silver ; so that the quartzose matrix was equal to 
437 grains. 
d. The solution a being concentrated by evaporation, crystals of 
muriated lead were deposited, to the amount of 330 grains, equivalent 
to 248 of metallic lead. 
e. Having thus separated the lead, the remainder of the solution 
was largely diluted with alcohol, by which a white oxide of tellurium 
was thrown down ; this oxide being re-dissolved by muriatic acid, and 
again precipitated by caustic soda, afforded 178 grains of oxide, equi- 
valent to 148 grains of reguline tellurium. 
/. The alcoholic solution was next distilled, by which the alcohol 
was separated ; the residual fluid being diluted with water, was treated 
with nitrate of mercury, in the way already described, by which a but- 
ton of gold weighing 41.5 grains was obtained. 
g. The residual fluid of / was saturated with carbonated soda, and 
boiled, by which a bluish-grey precipitate was obtained ; by digestion 
in muriatic acid it dissolved, and oxy-muriatic acid gas was produc- 
ed ; the muriatic solution being then supersaturated with carbonated 
ammonia, there was deposited carbonated manganese, mixed with iron, 
to the amount of 92 grains. 
h. The ammoniacal solution was of a blue colour, upon which it was 
supersaturated with sulphuric acid, and a plate of iron being immersed 
in the fluid there were deposited 6 grains of copper. 
The above abridged account of Klaproth’s analyses of the ores of 
tellurium is extracted from Messrs. Aikin’s Dictionary, and contains a 
variety of instructive details to the student in analytical chemistry. ANALYSIS OF THE 
Section XXII. Of the Combinations of Selenium. 
1480. The compounds of this substance have hitherto been exa- 
mined by Berzelius only ; he discovered it, as has already been stated, 
in the sulphuret of iron from Fahlun, from which sulphur is obtained 
for the formation of sulphuric acid ; when burned for this purpose, a 
brown compound remains, which consists of sulphur, and a peculiar 
substance exhaling a strong smell of horse-radish when heated by the 
blow-pipe : this substance, called by its discoverer Selenium (from 
o-fAsfvsj, the moon), indicative of its analogy to Tellurium, was separated 
in minute portions from the brown compound by a very tedious analy- 
sis, of which the essential part consisted in digesting it to dryness in 
nitro-muriatic acid, adding water, and filtering; excess of muriate of 
ammonia, added to the filtered liquid, threw down selenium. 
In this state selenium fuses a little above 212°, assuming, when cool, 
a brown colour, metallic lustre, and crystalline texture. 
It combines with two proportions of oxygen, forming an oxide and 
an acid ; the acid consists of 100 selenium + 38 oxygen ; if, therefore, 
we regard it as containing 1 proportional of selenium -J- 2 of oxygen, 
the number 42 will represent selenium, and 58 selenic acid. But, ac- 
cording to Berzelius’s analyses of the Seleniate of Baryta, it is compos- 
ed of 
Selenic acid 
100.0 
Baryta 
137.7 
and these numbers give 56.6 as the equivalent of the acid. 
1481. Selenium combines with chlorine, forming a volatile yellow 
compound : its action upon iodine has not been examined. Combined 
with potassium, and acted on by dilute muriatic acid, a colourless gas is 
disengaged, somewhat resembling sulphuretted hydrogen in its odour, 
and extremely irritating : it is soluble in water, reddens vegetable blues, 
and causes precipitates in metallic solutions. This gas, which is a true 
seleniuretted hydrogen, consists of 1 proportional of selenium -f- 1 of hy- 
drogen. 
1482. Sulphuret of Selenium is an orange-coloured compound, form- 
ed by passing sulphuretted hydrogen gas through a solution of selenic 
acid in water. It appears to be a sesqui-sulphuret, containing 3 pro- 
portionals of sulphur + 2 of selenium. 
1483. Phosphuret of Selenium is a fusible brown compound, which 
has not been analyzed.—Berzelius. Annales de Chemie et Physique, 
ix. Annals of Philosophy, xiii. Thomson’s System, 6th Edit., i. 297. 
1484. The following analysis of a supposed ore of tellurium, from 
Sweden, by Berzelius, and in which he discovered selenium, I subjoin 
as an example of his method of proceeding (Children’s Translation of 
Thenard on Analysis, 408.) : 
a. 100 parts of the purest portions of the mineral, carefully selected, 
were dissolved in boiling nitric acid, the solution diluted with boiling 
water, and filtered ; the clear liquor gave a precipitate with solution of 
common salt, and the matter which remained on the filter was washed 
with boiling diluted nitric acid, as long as the washings were rendered 
turbid by solution of sea-salt. COMBINATIONS OF SELENIUM. 
The chloride of silver, after being washed, dried, and fused, weigh- 
ed 50.7 parts, equal to 38.93 of silver. The substance remaining on 
the filter consisted of silica and stony matter, and weighed, after being 
heated, 4 parts. 
b. The liquid from which the silver had been separated was precipi- 
tated by sulphuretted hydrogen gas ; the precipitate re-dissolved in 
aqua regia, and the solution concentrated till the nitric acid was entire- 
ly decomposed. It was then diluted with water, and sulphite of ammo- 
nia added, when the liquid gradually became turbid, and acquired a 
cinnabar red colour. After some hours it was boiled, and small por- 
tions of sulphite of ammonia added from time to time. The boiling 
was continued two hours, in order to precipitate the Avhole of the se- 
lenium ; collected, dried, and heated nearly to fusion on the filter, it 
weighed 26 parts. 
c. From the liquid, separated from the selenium, and deprived of its 
sulphurous acid by boiling, subcarbonate of potassa threw down a green 
precipitate, which, when washed, dried, and heated red, was converted 
into black oxide of copper, and weighed 27 parts, equivalent to 21.55 
of copper. This oxide, dissolved in muriatic acid, gave a blue solu- 
tion, with an excess of ammonia. The alcaline liquor, from which the 
carbonate of copper had been separated, still retained a greenish tinge ; 
it was concentrated and slightly acidulated with muriatic acid, and a 
further precipitate of 1.5 part of copper separated by a plate of iron, 
which makes the whole of the copper 23.05. 
d. The liquid, precipitated by sulphuretted hydrogen, (b) was de- 
prived of the excess of gas by boiling, and mixed with caustic ammo- 
nia, which threw down a yellowish precipitate, weighing, when dried, 
1.8 parts, and was a mixture of oxide of iron with a little alumina. 
The remaining solution was mixed with subcarbonate of potassa in ex- 
cess, and evaporated to dryness. The saline mass, re-dissolved in 
water, left a white earth, which, heated red, weighed 3.4 parts. Sul- 
phuric acid, mixed with this earth, occasioned an effervescence, and by 
evaporation became gelatinous, and deposited silica ; it appeared also 
to contain magnesia, but it was not particularly examined, as these earths 
were evidently foreign to the ore. 
The results of the analysis then are, 
Silver 
. 38.93 
Copper 
. 23.05 
Selenium 
. 26.00 
Earthy and foreign substances 
. 8.90 
Loss 
. 3.12 
• 
100.00 
The loss must be partly attributed to the carbonic acid of the carbo- 
nate of lime ; still more to selenium, which it is difficult to separate 
entirely ; and partly to the loss unavoidable in this sort of experiments. 
Section XXIII. Of the Combinations of Arsenic. 
1485. The method of separating arsenic from some of its combina- 
tions, and estimating its quantity has already been adverted to; some ANALYSIS GF THE 
further account of the process, and of the analysis of arsenical combi- 
nations remains to be given in this section. 
Where the object is merely to drive off the arsenic contained in any 
ore, it may be effected by reducing it to powder, mixing it with saw- 
dust, or charcoal, and applying a dull red heat for some hours ; the 
carbonaceous material, by keeping the arsenic in the metallic state 
facilitates its escape in the form of vapour, and by dividing the mate- 
rial, prevents its running into lumps by partial fusion. 
1486. To estimate the quantity of iron in the arsenical pyrites, 
Messrs. Aikins advise the following as a short and convenient process : 
“Add to the powdered ore dilute nitric acid, and digest in a gentle heat; 
this will dissolve all the arsenic and iron, whilst most of the sulphur, 
with the siliceous residue, will remain undissolved. Pour off’ the ni- 
trated solution, mix with it about twice as much powdered charcoal as 
the quantity of ore employed, and evaporate nearly to dryness ; put 
the residue into a tall crucible, and apply a brisk red heat for about ten 
minutes, by which time the arsenic will be almost entirely driven off 
in copious fumes, and the residue will consist of little else than char- 
coal and oxide of iron. Spread this upon a heated tile, till the char- 
coal is almost burned off by which any arsenic still adhering will be 
dissipated, and the remaining oxide of iron may be reduced, or es- 
timated as mentioned under that metal. The nitrous acid is prefer- 
able to the muriatic in this process, as the latter, when strongly heated, 
volatilizes part of the iron, and renders the assay incorrect.”—Dic- 
tionary, i. 95. 
1487. In the analysis of ores containing arsenic, the most certain 
method of estimating its quantity, consists in acidifying it by nitric 
acid; the arsenic acid may then be thrown down, with due precau- 
tions, by nitrate of lead, and the proportion of arsenic deduced from 
that of the arseniate of lead ; the following process, for instance, may 
be followed in the analysis of the sulphuret of arsenic and iron (1059) : 
a. Digest 100 grains of the ore in fine powder, in nitric acid, a little 
diluted, so as sufficiently to moderate its action; a portion of sulphur 
will remain undissolved, together with silica, if any be present, which 
may be separated, washed, and burned, in order to obtain the silica. 
b. The acid solution containing nitric, sulphuric, and arsenic acids, 
and oxide of iron, may now be supersaturated with solution of soda, 
and the precipitate boiled in the alcaline liquor, which, being filtered 
off, leaves peroxide of iron, by which, when dried and ignited, the 
equivalent of the metallic iron in the ore is obtained. 
c. Neutralize the filtered alcaline liquor with nitric acid, and pour 
in nitrate of lead, which will give a precipitate of sulphate of lead 
and arseniate of lead ; collect and wash it, and digest it in dilute nitric 
acid, which will take up the arseniate, but leave the sulphate of lead ; 
the arseniate may again be obtained by saturating with soda. 
d. Estimate the sulphur in the sulphate of lead, and add it to that 
procured by process a. 100 parts of the arseniate of lead are equiva- 
lent to 56.5 of metallic arsenic. 
1488. Mr. Chenevix, in the Philosophical Transactions for 1801, has 
given some valuable details respecting the analysis of several ores of 
copper; the native arseniate of copper (1038) he examined as fol- 
lows : 
The ore was first heated to expel and estimate the water; it was NATIVE ARSENIATE OF LIME. 
then digested in dilute nitric acid, and nitrate of lead poured in, to 
form arseniate of lead, part of which being held in solution by excess 
of nitric acid, the liquor was evaporated nearly to dryness, and alcohol 
added, which occasioned the complete separation of the whole of the 
arseniate of lead ; the remaining solution containing the copper was 
then boiled with potassa and the oxide of copper collected. 
1489. Pharmacolite, or Native Arseniate of Lime, was submitted to 
the following satisfactory analysis by Klaproth.—Essays, ii. 221. 
a. 100 grains lost, by being moderately heated in a porcelain cruci- 
ble 22i grains. As in this operation, neither by the smell nor by the 
sight, any volatilization of any principle could be observed, this loss of 
weight must have been caused by the escaping of the water of crystal- 
lization. On the other hand, the specimens had undergone no other 
change by this heating, except their surface being rendered a little 
duller. But the places spotted red from the cobaltic crust, had now 
assumed a light-bluish colour. 
b. Those 77£ grains which remained after the ignition, dissolved in 
nitric acid, leaving a grey residue of 6 grains of siliceous, mixed with 
argillaceous, earth. 
c. The filtered nitric solution, which somewhat inclined to the red- 
dish, was evaporated to a smaller volume, and mixed with a solution of 
acetate of lead as long as any precipitation ensued. The precipitate, 
when collected, washed and dried at a raised temperature, weighed 
138 grains. It consisted of arseniated lead, = 46.5 grains arsenic 
acid. 
d. What remained of the fluid after the separation of the precipi- 
tate, together with the washings (c) was evaporated to some degree, 
during which green-coloured borders appeared on the inner surface of 
the vessel. In order to separate the small quantity of undecomposed 
acetate of lead, it might yet have contained, I added the requisite quan- 
tity of muriatic acid. When, upon farther evaporation no muriate of 
lead any longer appeared, I mixed the fluid with sulphuric acid. This 
produced a copious precipitate of sulphated lime, which being collected 
on the filter, washed with weak spirit of wine and heated to redness, 
weighed 54 grains. Therefore, since in 100 parts of ignited gypsum 
the pure calcareous earth amounts to 42| parts, the mentioned 54 
grains determine the portion of lime contained in the fossil examined 
at 23 grains. 
e. The remainder of the liquor was neutralized with carbonate of 
soda, and reduced to the state of siccity. On re-dissolving in water 
the dry saline mass, there remained a powder of the colour of flax- 
blossoms, and i grain of weight, which tinged the borax-glass with a 
fine deep blue, and thus proved to be an oxide of cobalt. 
Those 100 grains of pharmacolite, submitted to this analysis, have, 
therefore, been decomposed into 
Acid of arsenic . . . 
. . . 46.50 
Limb 
. . . 23 
Oxide of cobalt . . . 
. . . 0.50 
Aluminous silex . . . 
. . . 6. 
Water 
98.50 ANALYSIS OF THE 
But since the cobaltic oxide is here but casually admixed, as also the 
siliceous earth originates merely from the granitic matrix, it follows 
that, after subtracting these, the proportions of the constituent parts 
in the pure pharmacolite, are, 
Acid of arsenic . • . . 
Lime 
... 25 
Water 
1G0. 
Section XXIV. Of the Combinations of Molybdenum. 
1490. The native Molybdaie of Lead (1076) was analyzed nearly as 
follows by Mr. Hatchett: 
a. The iron and molybdic acid were separated by the action of hot 
sulphuric acid ; the silica and lead (in the state of sulphate,) were left 
undissolved. 
b. The acid liquor, saturated by ammonia, deposited oxide of iron, 
which being separated, the whole was evaporated to dryness, and 
heated to drive off sulphate of ammonia, and the dry residue was pure 
molybdic acid. 
c. The undissolved residue of a was boiled with carbonate of soda, 
and afterwards digested in dilute nitric acid : the carbonate of lead was 
dissolved, and the silica remained. 
d. The nitrate of lead was decomposed by sulphuric acid, and when 
the sulphate of lead had been separated, the residual liquid was satu- 
rated with ammonia, which threw down a small additional portion of 
oxide of iron. 
The results of this analysis were, 
Molybdic acid . . . 
Oxide of lead . . . 
Oxide of iron . . . 
. . . 2.08 
Silica 
98.76 
1491. The analysis of the sulphuret of molybdenum may be per- 
formed by the action of nitric acid, which separates part of the sulphur, 
and acidifies the remainder as well as the molybdenum ; the quantity 
of sulphur being ascertained by weighing the separated portion, and 
precipitating by nitrate of baryta that which is acidified, the loss of 
weight gives the proportion of molybdenum, and the excess of weight 
of the molybdicacid, above the deficiency, gives the proportion of oxy- 
gen united to the molybdenum to constitute molybdic acid. According 
tq Bucholz, the sulphuret of molybdenum is composed of 
Molybdenum . . 
. 60 
Sulphur 
ICO ORES OF TUNGSTEN. 
These numbers nearly correspond with the preceding estimate of 
the composition of this ore (1078); and if we consider it as a bi-sul- 
phuret, it will consist of 
1 Proportional of molybdenum . . 
— 47 
. . 16X2 = 32 
79 
Section XXV. Of the Combinations of Chromium. 
1492. Two methods of analyzing Chromate of Lead (1088) have 
been pointed out by Vauquelin (Journal des Mines, No. 34.) The 
first consists in repeatedly boiling the finely powdered ore in solution 
of carbonate of potassa, by which carbonate of lead and chromate of 
potassa are formed ; and the second, by digesting it in muriatic acid, by 
which muriate of lead is produced, and the chromic acid obtained dis- 
solved in the excess of muriatic acid. 
1493. Chromate of Iron (1087) is a more refractory compound, but 
it may be decomposed by the alternate action of potassa and muriatic 
acid (,Journal des Mines, No. 55.) The ore, in fine powder, should be 
heated red hot, with its weight of caustic potassa, for an hour, and 
the residue washed with water. The insoluble portion may then be 
boiled in muriatic acid, and, when no longer acted upon, washed, dried, 
and ignited as before ; by the alternation of these processes, it will 
ultimately be resolved into an alcaline and acid solution; the former, 
neutralized by nitric acid, lets fall a portion of alumina and of silica, 
and holds chromate of potassa in solution ; add to it nitrate of lead, by 
which chromate of lead is thrown down, and may be decomposed by 
muriatic acid. The muriatic solution, evaporated and diluted, lets fall 
silica, and ammonia throws down oxide of iron and alumina, which may 
be separated by potassa ; evaporate to dryness, and Heat to separate 
muriate of ammonia ; the chromic acid remains. 
Section XXVI. Of the Combinations of Tungsten. 
1494. W. To ascertain tlie component parts of Tungstate of Lime, 
(1093) Klaproth digested 100 grains of it in fine powder with hot ni- 
tric acid, and then decanted the supernatant liquor from the yellow re- 
sidue ; upon which last, after edulcoration, he poured liquid ammonia, 
and put it in a moderately warm place. This alcali took up that por- 
tion of the tungstic oxide, which had been set free by the nitric acid ; 
and thus caused the yellow colour to disappear. The residue was 
treated twice more, by nitric acid and ammonia. In this way the total 
decomposition of the fossil was effected ; so that only 2 grains of silica 
remained. ANALYSES OE THE 
b. The nitric solution was then neutralized with ammonia. But ai 
no change ensued, it was precipitated, in a boiling heat, with carbo- 
nated soda ; and the precipitate washed and dried. It weighed 33 
grains, and consisted of carbonate of lime, which, however, on re-dis- 
solution in weak nitric acid, deposited 1 grain of silica. 33 grains of 
carbonate of lime are equivalent to 17.60 grains of lime. 
c. The ammoniacal solution afforded, by evaporation in a low heat, 
slender needle-shaped crystals. When thoroughly desiccated the 
mass was ignited in a platinum crucible. The tungstic oxide which 
then remained had the form of a heavy, greenish-yellow powder, and 
weighed 77J grains. 
Consequently the 100 grains of tungstate of lime have afforded 
Yellow oxide of tungsten (tungstic acid) 
Lime 
Silica 
77.75 
17.60 
3. 
98.35 
1495. The examination of wolfram (1092) has not as yet been very 
satisfactorily accomplished, but the analysis of Messrs. D’Elhuyars is 
probably not far from the truth (Memoires de VAcad. de Toulouse, ii.) 
Their result is as follows : 
Tungstic acid 
. . . . 64.0 
Oxide of manganese . . . 
. . . . 22.0 
Oxide of Iron 
. . . . 13.5 
99.5 
Section XXVII. Of the Combinations of Columbium. 
1496. The original analysis of the Columbite (1102) from North 
America, by Mr. Hatchett, is detailed in his paper in the Phil. Trans. 
for 1802. 
This mineral, which is a compound of the oxides of columbium, 
iron, and manganese, was rendered soluble by the alternate action of 
fused carbonate of potassa and muriatic acid ; the muriatic solutions 
contain the iron and manganese, and the columbium is retained in com- 
bination with the potassa, from which it may be precipitated by nitric 
acid. 
Dr. Wollaston in his experiments to show the identity of##lumbium 
and tantalum (Phil Trans. 1809,) mixed 5 parts of the ore with 25 
of carbonate of potassa, and 10 of borax The resulting mass was 
softened with water and digested in excess of muriatic acid, which took 
up every thing, except the oxide of columbium. The muriatic solu- 
tion was neutralized with carbonate of ammonia ; and the iron se- 
parated by succinate of ammonia ; after w'hich the manganese was se- 
parated by prussiate of potassa. The results of this analysis are given 
above (1090.) COMBINATIONS OF NICKEL. 
Section XXVIII. Of the Combinations of Nickel. 
1497. The separation of nickel from cobalt has already been des- 
cribed (1466) and the analysis of meteoric iron has also been elsewhere 
adverted to (1126). It remains here to give a general formula for 
the analysis of ores containing nickel, which is often rendered extreme- 
ly complex, from the variety of substances united in some of its ores. 
The following general directions are extracted from Messrs. Aikin’s 
Dictionary (Art. Nickel,) and the process has been repeated in the 
Laboratory of the Royal Institution with sufficiently satisfactory results. 
i. The ore being ground to an impalpable powder must be digested 
with nitric acid considerably diluted ; nitrous gas will be given out, 
and by two or three digestions every thing soluble will be taken up. 
ii. The insoluble portion, consisting for the most part of sulphur 
and silex, is to be dried, weighed, and then heated ; the sulphur (a) 
will burn off, and its amount may be ascertained by the difference of 
weight before and after ignition. The residue after being boiled in a 
little nitric acid is pure silex (6). 
iii. Add together both the nitric solutions, nearly saturate the liquor 
with pure soda, evaporate it considerably, and then pour the solution 
into cold distilled water, by which the oxide of bismuth (c) will be pre- 
cipitated. 
iv. To the filtered solution add muriate of soda drop by drop as 
long as any precipitate falls down ; this is muriate of silver (d). 
v. Now evaporate the solution nearly to dryness, and boil it with 
strong nitric acid as long as any nitrous gas is given out : during the 
process red oxide of iron (e) will be precipitated. 
vi. Having removed the oxide of iron, nearly saturate the liquor 
with soda, and pour in nitrate of lead as long as any arseniate of lead 
(/) is precipitated, which separate by the filter. 
vii. The nitrous solution being now decomposed by carbonated soda, 
and the washed precipitate digested in liquid ammonia, oxide of iron 
(g) mixed with alumine ([h) will be left behind, which may be separat- 
ed in the usual way by potassa. 
viii. The ammoniacal solution is to be slightly supersaturated with 
nitric acid, and a bar of ironbeing immersed in it will separate the cop- 
per (i) ; after which the liquor is to be decomposed by carbonated 
soda, and the precipitate again digested in ammonia, that the iron used 
for separating the copper may be got rid of. 
ix. The solution, containing now only nickel and cobalt, is to be 
treated according to Mr. R. Phillips’s [Phil. Mag. xvi. p 312,) method 
as follows : Evaporate the liquor till the excess of ammonia is driven 
off, which may be known by the vapour ceasing to discolour moist tur- 
meric paper ; then largely dilute it, and pour in pure potash or soda, 
as long as any precipitation takes place ; what falls down is oxide of 
nickel (k). 
x The cobalt (Z) alone remains in solution, and may be readily se- 
parated, by accurately saturating the liquor with nitric acid, and then 
adding carbonated soda. 
The above general mode of proceeding is also applicable to the 
analysis of nickel ochre, except that it should first of all be digested in ANALVSI5 OF THE 
water, to dissolve out any sulphate of nickel which it may accidentally 
contain. » 
1498. The results of the following analysis of the crystallized sul- 
phate of nickel, which was made with a view to verify the equivalent 
number of the metal, are given above (1125). 
a. 100 grains of the crystals were heated in a porcelain crucible, to 
dull redness, for ten minutes ; they crumbled into a pale green pow- 
der, perfectly soluble in water, consequently no acid had been expell- 
ed, and lost 45 grains — water of crystallization. 
b. The remaining 55 grains of dry salt were dissolved in two ounces 
of water, to which nitrate of baryta was added, as long as it occasion- 
ed a precipitation ; the sulphate of baryta thus formed being collected, 
washed, dried, ignited, and weighed, amounted to 83 grains = 28.25 
sulphuric acid. 
c. The filtered solution from which the sulphuric acid had been 
thrown drown in the last process, was now mixed with a little sulphate 
of soda, to separate excess of baryta, filtered, concentrated by evapo- 
rating, and rendered alcaline by potassa; the precipitated oxide of 
nickel was then thoroughly edulcorated, dried, and exposed to a dull 
red heat, till it ceased to loose weight; it amounted to 26.5 grains. 
The salt, therefore, was thus decomposed into 
Water of crystallization . . 
Sulphuric acid 
Oxide of nickel 
. . 45.00 
99.75 
Section XXIX. Of the Combinations of Mercury. 
1499. What is termed native mercury is usually an amalgam, con- 
taining a variable portion of silver, and often a trace of gold ; it may 
be analyzed by exposure to heat, which dissipates the mercury, leav- 
ing silver and gold, separable by the action of dilute nitric acid. 
If the amalgam, besides gold and silver, contain bismuth, its quanti- 
ty may be judged of by solution in nitric acid, concentration by heat, 
and pouring the solution into a large quantity of pure water, by which 
the greater part of the bismuth will be thrown down in the form of 
white oxide ; but the analysis of complex amalgams is much simplified 
by previously expelling the mercury by heat, taking care that no other 
metal evaporates with it, which is sometimes the case at high tempe- 
ratures. 
1500. The analysis of Native Cinnabar (1182) may be effected in 
the following manner : 
a. Reduce it to powder, and digest it in a sand heat with dilute ni- 
tric acid ; wash the insoluble portion with hot water, and add the wash- 
ings to the nitric solution ; sulphur will thus be separated, which may 
be dried and weighed ; it may possibly contain silica, and a little oxide 
of iron; if so, these are left after the combustion of the sulphur, and 
may be separated by dilute muriatic acid. BISMUTHIC SILVER. ORE. 
b. Add carbonate of potassa in excess to the nitric solution, collect 
and dry the precipitate, having previously boiled it for a minute or two 
in the alcaline liquor, and mix it with a little charcoal: put the mixture 
into a small coated retort, and at a red heat the mercury may be dis- 
tilled over ; the residue may be examined for alumina, lime, oxide of 
iron, or other extraneous matters. 
1501. The Native Murio-sulphate of Mercury (1156) may be dis- 
solved in acetic acid, by which a portion of metallic mercury is usually 
separable from it; nitrate of baryta, added to the acetic solution, se- 
parates the sulphuric acid in the state of sulphate of baryta, which 
being removed, nitrate of silver will throw down chloride of silver; 
immerse a plate of iron into the remaining solution to precipitate me- 
tallic mercury, or throw it down by carbonate of potassa, and distil with 
a little charcoal. 
1502. The assay of mercurial ores may be effected by mixing the 
powdered sample with half its weight of a mixture of equal parts of 
lime and iron filings, and submitting it to distillation in the open fire, in 
a coated glass retort. 
Section XXX. Of the Combinations of Silver. 
1503. As instances of the analysis of complex silver ores, I have 
selected that of the bismuthic silver, and of the white silver ore, from 
Klaproth (Essays, i. 556, 145.) whose paper on the composition of va- 
rious silver ores may be strongly recommended to the attentive perusal 
of the student. 
a. Upon 300 grains of the Bismuthic Silver from Schapbach, in the 
Black Forest, I poured three ounces of nitric acid, diluted with one of 
water ; a great part of it dissolved, even in the cold ; the residue was 
again digested with one ounce of the same acid, in a gentle heat ; both 
solutions were filtered, mixed, and evaporated to a smaller volume ; 
during which process there separated some crystalline grains of nitrate 
of lead. 
b. The concentrated solution had a greenish colour ; when diluted 
with as much water as was requisite to re-dissolve that crystalline sedi- 
ment, it was poured into a large quantity of water ; this immediately 
acquired a milky appearance, and deposited a white precipitate, which 
weighed 44.5 grains, when collected, lixiviated, and dried in the air, 
and proved on further examination to be oxide of bismuth. 
c. Into the liquor that had been freed from this oxide, and was clear 
and colourless, I dropped muriatic acid, as long as it was rendered tur- 
bid by it : the precipitate did not appear to be mere muriate of silver, 
for this reason I digested it with nitric acid ; a considerable portion 
was thus re-dissolved, and left pure horn-silver behind ; which, upon 
careful collection, and desiccation in a brisk heat, weighed 46 grains : 
thus, the portion of pure silver is determined at 34.5 grains. 
d. The nitric acid, that had been affused upon the precipitate obtain- 
ed by the muriatic c, yielded by dilution with much water 32 grains 
more of oxided bismuth ; which, with the preceding 44.5 b, gave to- 
gether 76.5 grains. ANALYSIS OF THE 
c. The remainder of the fluid was farther reduced by evaporation, 
and in this process muriate of lead separated from it in crystals ; this 
liquor was then combined with such a quantity of sulphuric acid as was 
requisite to re-dissolve those crystals, and a second time evaporated; 
the precipitate which thence ensued was sulphate of lead, weighing 19 
grains, when duly collected, washed, and dried. 
f. What still remained of the solution, after its having been freed 
from the lead before contained in it, was saturated with caustic ammo- 
nia added in excess : in this way a brown ferruginous precipitate was 
produced which was rapidly attracted by the magnet, and weighed 14 
grains, when after previous desiccation, it had been moistened with 
linseed oil, and well ignited : for these we must reckon 10 grains of 
metallic iron. 
g. The liquor which had been supersaturated with ammonia, and 
which by its blue colour showed that it held copper in solution, was 
next saturated to excess with sulphuric acid ; on immersing then a 
piece of polished iron into it, two grains of copper were deposited. 
h. The grey residue of the ore, that was left behind by the nitric 
acid a weighed 178 grains ; but when its sulphureous part had been 
deflagrated in a crucible gently heated, it weighed only 140.5 grains ; 
this determines the portion of sulphur at 37.5 grains. 
i. These 140.5 grains were digested with 3 ounces of muriatic acid 
in a heat of ebullition, and this process was repeated once more with 
1.5 ounces of the same acid ; these solutions, by means of evapora- 
tion, yielded muriate of lead in tender spicular, and likewise in broad 
striated, crystals; which, when again dissolved in the requisite quan- 
tity of boiling water, then combined with sulphuric acid, and evapo- 
rated, yielded 89 grains of sulphated lead ; thus the whole quantity of 
this sulphate, including the 19 grains mentioned at e, amounted to 1G8 
grains ; for which, according to comparative experiments, 76 grains of 
reguline lead must be put in the computation. 
k. That portion of the ore examined, which still remained after all 
the constituent parts before-mentioned have been discovered, consist- 
ed merely of the grey quartzose matrix, the weight of which, in the 
ignited state amounted to 70 grains. 
Therefore those 300 grains of bismuthic silver ore mentioned above 
were decomposed into 
Lead, i 
Bismuth d 
Silver, c 
.... 62.20 
.... 34.50 
Iron,/ 
.... 10. 
Copper g 
9 
Sulphur, h 
.... 37.50 
Quartzose matrix, k ... . 
.... 70. 
292.20 
It follows, from this statement, that, exclusively of the quartzose 
gangue, the constituent parts of the bismuthic silver are in the 100, WHITE SILVER ORE. 
Lead 
Bismuth 
. . • . . . 27. 
Silver 
15. 
Iron 
4.30 
Copper 
0.90 
Sulphur 
16.30 
96.50 
1504. Klaproth treated the white silver ore from Freyberg, nearly 
is follows : 
a. The ore was brittle, and easily levigated into a blackish powder. 
h. Upon 400 grains in powder he poured 4 ounces of nitric acid, 
and 2 of water ; after sufficient digestion in a gentle heat, the solution 
was decanted, and the residue again treated with 2 ounces of the acid ; 
this mixture was next diluted with eight parts of water, and digested 
for some time ; he then separated the undissolved residue, consisting 
of a greyish-white powder, which, after washing and drying, weighed 
326 grains. 
c. The solution, which was nearly colourless, was combined with 
common salt, by which muriated silver was produced; and the next 
day crystals of muriate of lead were found ; on this, therefore, he 
boiled the whole precipitate in a large quantity of water, by means of 
which the muriated lead was re-dissolved, and separated from the mu- 
riate of silver, collected on the filter : this last, when reduced by fu- 
sion with soda, yielded 81.5 grains of reguline silver. 
d. What remained of the solution, together with the liquor obtained 
by the decoction of the horn silver, he evaporated in part; and by 
adding a saturated solution of sulphate of soda, obtained from it 45 
grains of sulphate of lead, which, upon reduction, afforded 32 grains 
of lead in the metallic state. 
e. The remaining part of the solution was saturated with pure am- 
monia, upon which a light-brown precipitate fell, weighing 40 grains, 
when edulcorated and ignited in a low heat; as that precipitate had 
the appearance of a mixture of iron and alumina, he dissolved it again 
in nitric acid, and precipitated first the iron by prussiate of potassa, 
and afterwards, by the addition of soda, a loose earth, which, when 
desiccated and ignited, weighed 28 grains, and upon trial with sulphu- 
ric acid, was found to be aluminous oarth ; this being subtracted from 
the above 40 grains, leaves 12 for the oxide of iron, which may be es- 
timated at 9 grains of metallic iron. 
f. After this the residue that remained from the solution of the ore, 
dissolved in nitric acid b, was subjected to a closer examination : Kla- 
proth attempted to decompose it by muriatic acid, repeatedly poured 
upon it, and in every instance digested over it in a heat of ebullition. 
The process was rendered somewhat difficult by the crystals, which 
were deposited from the solution as soon as the heat fell below the 
boiling point; similar crystals likewise shot on the paper, through 
which the solution, though yet boiling, was filtered, and he gradually 
re-dissolved them in warm muriatic acid; at last there remained 51 
grains of sulphur, leaving, after deflagration upon a test, two grains of 
a grey residue, one of which dissolved in muriatic acid, and was added 
to the preceding solution ; the other grain was siliceous earth. The 
true quantity of the sulphur, therefore, amounted to 49 grains. 394 
ANALYSIS OP THE 
g. While the muriatic solution was cooling, it deposited a quantity 
of acicular crystals ; these being separated, one half of the remaining 
fluid was distilled over in a small retort, and from the solution thus con- 
centrated more crystals similar to the first were deposited ; this treat- 
ment was continued until no more crystals would form; when these 
crystals, collected together, were mingled with twice their weight of 
black flux, and reduced in an assay-crucible, thinly lined with char- 
coal-dust, they afforded 160f grains of lead; this lead, subjected to 
cupellation, emitted at the first application of heat a few antimonial 
vapours ; it then fined quietly, and left a button of silver, weighing a. 
of a grain ; this determines the proportion of lead at 160.25 grains ; 
from which, however, a trifling quantity should be deducted for the 
portion of antimony before-mentioned, though it could not be well de- 
termined, besides that it could not weigh much above half a grain. 
h. The fluid separated from the muriate of lead, concentrated, and 
diluted with a large quantity of water, deposited its metallic part, which, 
in the form of a subtle white powder, was only oxide of antimony, and 
being kneaded into a mass with soap, was reduced in a luted assaying- 
crucible, by means of black flux, into 28.5 grains of pure reguline an- 
timony ; some more small globules were found adhering to the lid of 
the vessel, of which I collected 3 grains ; but still a small portion ap- 
peared to have escaped through the joinings, and for this reason, the 
true amount of antimony which I obtained may be reckoned at some- 
what more than the 31.5 grains. 
Hence the product of the 400 grains of the white silver ore here 
analyzed consisted of 
Silver . . ,\c ' ' ' 
18 • • • 
Lead . . . . \d * * * 
Reguline antimony A . 
Iron, e , 
. 81*) 
i L 
0 8 3 
. 32 ) 
. 1601 $ 
8If grs, 
192* 
. 311 
9 
Sulphur,/ 
. 49 
Alumina, e 
. 28 
Silex,/ . 
1 
392f 
Which in 100 parts makes 
Silver 
Lead 
Antimony 
Iron 
Sulphur 
Alumine 
Silex 
98.09 COMBINATIONS OF PLATINUM. 
Section XXXI. Of the Combinations of Gold. 
1505. In the Section on the combinations of Tellurium, I have 
quoted Klaproth’s analyses of some of its ores containing gold ; the 
only proper ore of this metal is native gold, (1275) which is occasion- 
ally found in veins, but of which by far the greatest proportion occurs 
dispersed in a granular form through certain alluvial strata. In this 
state, silver and copper are the principal metals with which it is combin- 
ed, and the analysis is sufficiently simple ; the ore may be digested in 
nitro-muriatic acid ; the solution evaporated nearly to dryness, and 
again diluted, leaves the silver in the state of chloride ; a strong solu- 
tion of proto-sulphate of iron may then be used to throw down the 
gold (1276), and the copper may be separated by immersing a plate of 
iron into the last filtered liquor. 
If the proportion of silver and copper alloyed with the gold be con- 
siderable, the analysis may be simplified by using nitric acid in the first 
instance, which extracts the silver and copper, leaving the gold untouch- 
ed : muriatic acid mav then be poured in, to throw down the silver, 
and the copper separated by iron, as before ; or by precipitation by 
potassa, and ignition, which gives it in the state of peroxide. 
Section XXXII. Of the Combinations of Platinum. 
1506. We are indebted to Dr. Wollaston and to Mr. Tennant (Phil. 
Trans. 1803.) for our knowledge of the component parts of the ore of 
platinum, as imported from South America. In this state it generally 
contains the following metals, exclusive of small particles of silica, and 
a variable portion of mercury, viz. : platinum, gold, palladium, rho- 
dium, iridium, osmium, iron, copper, and lead ; and the following is 
the process for their separation : 
The mercury may be driven off by heat, a process which renders 
the platinum yellower in consequence of the appearance of the grains 
of gold ; it may then be digested in nitro-muriatic acid diluted with its 
bulk of water, which takes up gold, iron, and a little platinum ; if the 
remaining ore be now digested in nitro-muriatic acid by far the largest 
portion will be dissolved, and there will remain a black powder : to the 
nitro-muriatic liquor add a solution of muriate of ammonia, which will 
occasion the separation of the greater part of the platinum in the state 
of a very difficultly soluble ammonio-muriate, and which may be sepa- 
rated upon a filter; in the filtrated liquor immerse a plate of zinc, 
which will throw down lead, rhodium, palladium, and a portion of pla- 
tinum ; the lead may be separated by very dilute nitric acid ; dissolve 
the residue in nitro-muriatic acid, add common salt, and evaporate to 
dryness ; this residue, composed of the soda-muriates of platinum,pal- 
ladium, and rhodium, is to be digested in alcohol, which dissolves the 
triple salts of platinum and palladium, but not that of rhodium (1213), 
which therefore is thus separated ; to the alcoholic solution add solw- ANALYSIS OF SILICEOUS 
tion of muriate of ammonia, which throws down the platinum, and 
leaves the palladium in solution, which maybe precipitated by ferrocy- 
anate of potassa (1216). 
The insoluble black powder, by alternate fusions with potassa, and 
boiling in muriatic acid is resolved into osmium (1206) soluble in the 
alcali, and iridium (1209) in the acid. 
Section XXXIII. Of Siliceous and Aluminous Combinations. 
1507. The ready solubility of silica by fusion with the fixed alcalis, 
and its insolubility in the greater number of the acids, render its sepa- 
ration in most cases of analysis extremely easy. Muriatic acid, under 
certain circumstances, is capable of retaining a considerable quantity 
of silica, and the solution, when evaporated, assumes a gelatinous ap- 
pearance ; if ammonia be then added, and the whole evaporated and 
heated red-hot, the silica is obtained pure, and not again soluble in the 
acid. 
1508. Alumina, like silica, is soluble in potassa, and the addition of 
acids to the mixed alcaline solution throws down a compound which is 
not entirely decomposed by the action of those acids, which, under 
ordinary circumstances, readily dissolve alumina without acting upon 
silica ; a circumstance of which it is necessary to be aware, in certain 
cases of analysis. 
1509. If silica is predominant in a stone, it is in general rendered 
easily soluble by heating it in fine powder with potassa ; but there arc 
some of the hard aluminous compounds which are very difficultly act- 
ed on in this way; Mr. Chenevix found minerals of this class were 
most readily attacked by borax. One part of the mineral in fine pow- 
der, mixed with about three parts of glass of borax is to be strongly 
heated in a platinum crucible; the contents, when cold, are perfectly 
soluble by long digestion in muriatic acid ; the addition of carbonate 
of ammonia throws down the dissolved earths, which may be collect- 
ed, re-dissolved and examined as usual. Sir H. Davy has, in similar 
cases, recommended the use of boracic acid —Phil. Trans. 1805. 
1510. There are a few minerals which contain fluorine, or fluoric 
acid, (646) the presence of which is ascertained by heating the sub- 
stance in fine powder with sulphuric acid, either before or after its fu- 
sion with potassa, when vapours which act upon and corrode glass will 
be liberated. To ascertain the proportion of fluoric acid in a mineral, 
it may be fused with potassa, and treated by muriatic acid, to separate 
silica ; to the remaining liquid add excess of carbonate of potassa, and 
filter, neutralize the filtrated liquor with muriatic acid, and add 
muriate of lime, which will occasion a precipitate of fluate of lime, 
the purity of which is to be ascertained, and the quantity of fluorine 
and fluoric acid inferred from it. 
1511. Boracic acid, originally found in the Boracite (696) by West- 
rumb* has also been discovered by Klaproth in Datolite (xxiv. p. 319.) 
and in Botryolite, and more lately by Arfwedson and Berzelius in the 
green Tourmaline and Rubelite. The following is a sketch of M. Arf- 
wedson’s analysis. AN© ALUMINOUS COMBINATIONS. 
397 
A portion of the green tourmaline in tine powder, was strongly 
heated for an hour, with four times its weight of carbonate of baryta ; 
the mass was dissolved in muriatic acid, and the solution evaporated 
to dryness ; water, acidulated with mui’iatic acid, then dissolved every 
thing but the silica. 
The baryta was separated from the solution by sulphuric acid, and 
the other earths, with the oxides of iron and manganese, by an excess 
of carbonate of ammonia; the solution being separated from the pre- 
cipitate, and evaporated to dryness, a sulphate was obtained, which, 
when again treated with ammonia as before, dried, and heated red, re- 
dissolved in water without leaving any residuum ; this solution was 
freed from its sulphuric acid, by acetate of baryta, and the filtered 
liquid evaporated ; a gummy mass was obtained, which, by calcination 
in a platinum crucible, was decomposed, and afforded a fused alcaline 
mass, which proved to be lithia. “ I began to consider my work 
almost finished, (adds Mr. Arfwedson) when, on drying and heating a 
portion of the alcaline solution, I observed, at the moment the mass 
began to fuse, that it swelled up like borax, and left a glass, after cal- 
cination, of the same appearance as vitrified borax ; it was very proba- 
ble, therefore, that the mineral contained boracic acid, and I ascertained 
it by heating the fused mass with muriatic acid, which gave me, by eva- 
poration, a salt, partly soluble in alcohol, to which it imparted the 
property of burning with the greenish flame so characteristic of boracic 
acid.” 
To obtain the quantity of this acid, a portion of the mineral was 
fused with bi-sulphate of potassa; the mass boiled with alcohol, and 
the filtered liquid evaporated to dryness ; a substance remained equal 
to 1.1 per cent, of the weight of the tourmaline, and having all the 
properties of boracic acid.—Annales de Chimie, Vol. x., p. 93. 
1512. To the above observations, I shall add, as specimens of prac- 
tical analysis, two instances from Klaproth’s Essays, viz., his analysis 
•f the Spinell and of Kryolite : 
a. 100 grains of rough spinell from Ceylon, in picked crystals, pre- 
viously pounded to a coarse powder in a steel mortar, were triturated 
with water to an impalpable powder in a grinding-dish made of flint; 
after the powder of the stone, which was again dried, had been gently 
ignited, it showed an increase of weight of nine grains, arising from 
the particles abraded from the substance of the grinding-vessel. 
b. I then digested the powder with two ounces of muriatic acid; 
when the acid was evaporated nearly to dryness, I diluted the mass 
with water, threw it upon the filter, and saturated the yellow muriatic 
solution with caustic ammonia; a brown flocculent oxide of iron fell 
down, which, collected and ignited, weighed 1.25 grains. 
c. The liquor separated from that precipitate was concentrated by 
evaporation, perfectly neutralized with muriatic acid, and lastly com- 
bined with dissolved oxalate of potassa ; in consequence of this, oxa- 
late of lime precipitated, which, when carefully collected, and heated 
to redness in the cavity of a compact piece of charcoal, with the as- 
sistance of the blow-pipe, afforded .75 of a grain of lime. 
d. Upon the powder of the stone, extracted by the muriatic acid, 
was poured ten times its quantity of alcaline ley, one half of which 
consisted of caustic potassa, which mixture being first evaporated to 
dryness in a silver vessel, was afterwards ignited during the space of 398 
ANALYSIS OF SILICEOUS 
an hour ; when the mass had been again softened with hot water, it left 
on the filtering paper 54 grains of a yellow residue when dried in the 
air. 
e. These 54 grains were a second time mixed, and inspissated with 
a tenfold quantity of the same caustic lixivium, and afterwards ignited ; 
upon which the mass, softened again with water, deposited a residue of 
a fine pulverulent form, weighing 43 grains when dried in the air. 
/. I then neutralized the yellow alcaline solution (c£ and e) by means 
of sulphuric acid, and by affusing more acid, made a clear solution of 
the precipitate, which then formed ; carbonate of potassa added in a 
boiling state threw down from it a precipitate of a very great bulk, 
which after edulcoration was again dissolved in sulphuric acid ; this 
solution exhibited a slimy toughness, but it became perfectly fluid, when 
exposed to a raised temperature, and deposited a subtle white powder, 
which, after washing and desiccation in the air, weighed 95 grains : the 
sulphuric acid fluid, when separated from it, was set aside for a time. 
g. The above-mentioned 95 grains were then gently ignited-with 
thrice their quantity of caustic potassa ; when again liquified with 
water, and filtered, there remained only a slight residue, which after 
washing, dissolved in sulphuric acid, with the exception of a few re- 
maining particles. 
h. The portion taken up by the potassa in the alcaline solution g was 
precipitated by means of sulphuric acid ; but it dissolved again in the 
acid, when added to excess, and was afterwards precipitated by boiling 
with carbonated alcali : this precipitate, previously wrashed, was once, 
more dissolved in sulphuric acid. 
i. The whole of the sulphuric solutions, obtained at/g h, was eva- 
porated to a smaller compass ; the gelatinous consistence into which it 
congealed showed that a separation of siliceous earth had taken place : 
it was therefore largely diluted with water, digested, and the silex col- 
lected upon the filter. 
k. This done, the sulphuric solution was put in a state to crystallize, 
by dropping into it a solution of acetate of potassa, and evaporating it 
slowly ; it yielded at first regular and pure crystals of alum ; but as the 
solution assumed a green colour towards the end, I combined it with 
Prussian alcali ; a trifling precipitation ensued, of which the oxide of 
iron could not be estimated more than at one-fourth of a grain ; the 
solution being nowr freed of its ferruginous ingredient, was next decom- 
posed in a boiling heat by carbonated potassa, and the precipitate, when 
dissolved anew in sulphuric acid, was brought to a final crystallization, 
after which the alum then obtained was added to the foregoing. 
l. I now proceeded to the analysis of the 43 grains, that were left 
undissolved by the caustic alcaline ley e. These readily dissolved in 
dilute sulphuric acid, leaving some siliceous earth behind ; the solution, 
separated from this last, was then combined with a small portion of 
acetated potassa, and exposed to spontaneous crystallization by exhala- 
tion in the open air. At first there yet appeared some solitary crystals 
of alum; but afterwards it entirely shot into sulphate of magnesia 
(Epsom salt). 
m. To separate the sulphated magnesia, thus obtained, from the ad- 
mixed alum, it was strongly ignited in a porcelain vessel during half an 
hour, and the saline mass afterwards softened in water, and filtered; 
the aluminous earth, separated by this management, was afterwards AND ALUMINOUS COMBINATIONS. 
399 
dissolved in sulphuric acid, and in the proper manner crystallized into 
concrete alum. 
n. The pure solution of the sulphated magnesia was precipitated in 
a boiling heat by means of vegetable alcali. The magnesian earth, 
thus obtained in a carbonated state, weighed 20 5 grains when washed 
and dried ; but after strong ignition it weighed only 8.25 grains. 
o. All the washings (of which that at/, on precipitating the sulphu- 
ric solution by carbonate of potassa, retained the yellow colour of the 
first solution) were together evaporated to a dry saline mass ; when 
they had been re-dissolved in water, there still separated a little earth, 
which, along with the precipitate remaining at g, was ignited with caus- 
tic potassa, and then by sulphuric acid resolved into aluminous and si- 
liceous earths. 
p. The whole quantity of alum, obtained at him and o, amounted to 
665 grains. It was now dissolved in water, and in a heat of ebullition 
decomposed by carbonate of potassa. The aluminous earth thus ob- 
tained, when edulcorated with water, and dried in a moderate warmth, 
weighed 221 grains ; but after being purified by digestion with distill- 
ed vinegar, and subsequent saturation with ammonia, and being again 
edulcorated, and at last subjected for half an hour to an intense red 
heat, it weighed no more than 74.5 grains. 
q. I then ignited, for half an hour, the whole of the siliceous earth 
collected from i l o: its weight was 24.5 grains. Hence, subtracting 
the 9 grains which had been abraded from the flint-mortar a, there re- 
mained 15.5 grains belonging to the spinell. 
From this analysis it follows, that the constituent parts of the spinell 
in the 100 are 
Alumine, p . 
74.50 
Silex q ... . 
15.50 
Magnesia, n . 
S b • 
[ k . 
. 1.25 J 
. 0.2oj 
8.25 
Oxide of iron • 
1.50 
Lime, c. . . , 
0.75 
100.50 
The reason why, in this instance, there appears in the sum of the 
weights an excess of half a grain, rather than a loss, unavoidable in 
the usual course of such processes, is probably, that the ignition was 
not powerful enough to effect in those ingredients that high degree of 
dryness, which that stone possesses in its natural undecomposed state. 
1513. Analysis of the Kryolite; after some preliminary experiments, 
which taught him the existence of fluoric acid, soda, and alumina in 
this mineral, Klaproth proceeded as follows : 
i. 100 grains of triturated kryolite, to expel entirely the fluoric acid, 
were inspissated to dryness in a platinum crucible, with 300 grains of 
concentrated sulphuric acid. The residual mass, previously drenched 
with water, congealed on evaporation to a soft, granular saline mass, 
which readily liquified in a little water. 
ii. Caustic ammonia precipitated from the clear solution the alumin- 
ous earth weighing 46 grains, when edulcorated and dried, but 24 
grains when ignited. The solution of this earth, in dilute sulphuric 
acid, with the assistance of heat, and combined with a just proportion 
of potassa, shot into regular crystals of alum. 400 
ANALYSES OF THE 
iii. The fluid, from which the alumina had been precipitated, wa* 
neutralized with acetic acid, then combined with acetated baryta, and 
filtered, to separate the barytic sulphate, The clear fluid was now 
wholly evaporated, its dry residuum ignited in a platinum crucible, re- 
dissolved, and, after being rendered free by filtration, from the few 
adhering coaly particles, a second time evaporated to perfect dryness. 
It thus afforded 62i grains of dry carbonate of soda, equal to 36 grains 
of pure soda. This, saturated with acetic acid, crystallized all to ace- 
tate of soda. 
If now, from the quantity of the fossil employed, be subtracted the 
weight of alumina and soda obtained, the remainder will give the 
weight of the fluoric acid, including perhaps the water of crystalliza- 
tion. 100 parts of kryolite, therefore, consist of 
Soda 
36 
Alumina 
24 
Fluoric acid, including the water 
40 
100 
Section XXXIV. Of the Combinations of Zirconium. 
1514. Klaproth’s description of the discovery of zirconia, and of 
the method of separating it from the Jargon and Hyacinth of Ceylon, 
contain a very instructive lesson in analytical chemistry ; in those mi- 
nerals the zirconia is combined with silica, and with a trace of oxide of 
iron, the following mode of obtaining pure zirconia, suggested by 
M. M. Dubois and Silveira (Annales de Chimie et Phys. xiv.) furnishes, 
at the same time, a process for the analysis of the mineral, upon the 
whole less exceptionable than that of preceding chemists. 
Reduce the zircons to fine powder, and heat them in a red heat for 
an hour, with two parts of pure potassa; pour distilled water on the 
fused mass, and wash the insoluble portion upon a filter ; dissolve it in 
muriatic acid, and evaporate to dryness ; pour water on the residue, 
which leaves silica, and dissolves muriate of zirconia and iron ; filter, 
and add ammonia, which throws down zirconia and oxide of iron: 
wash the precipitate and boil it, while moist, in a solution of oxalic 
acid, which retains the iron, and forms an insoluble oxalate of zirconia ; 
collect and edulcorate the latter, and heat it to redness in a platinum 
crucible : in this state the zirconia, though pure, is insoluble in acids ; 
fuse it, therefore, with potassa, wash away the alcali, dissolve in muria- 
tic acid, and precipitate by ammonia ; the hydrate of zirconia now 
thrown down, when washed and dried, is pure and soluble. 
Section XXXV. Of the Combinations of Glucinum. 
1515. The composition of the beryl, and of the emerald, and the 
mode of obtaining from them pure glucina have been given above 
(1359); in this section therefore I shall merely give Klaproth’s ex- COMBINATIONS OP OI-UCINUM. 
amination of the emerald, as showing the mode of separating glucina 
in analyses.—Essays, ii. 177. 
a. 1G0 grains of light-green emerald were levigated in a flint mor- 
tar, by which their weight increased 2| grains. The powder of the 
stone was mixed with a solution of 250 grains of caustic soda, and in- 
spissated in a silver crucible ; upon which the dry mass was moderately 
ignited during 30 minutes. 
b. When this mass had cooled, it appeared white, and not easily 
softened in water. It was saturated to excess with muriatic acid, which 
effected a solution. This being evaporated, and afresh diffused in 
w'ater, was thrown upon the filter, in order to collect the siliceous 
earth, which, washed, dried, and ignited, weighed 63 grains, after de- 
ducting the 2J grains it received from the mortar. 
c. The muriatic solution was supersaturated with soda and boiled. 
The precipitate was soon again taken up by the fluid, excepting some 
loose ash-grey flocks, which, upon drying and ignition, weighed 24 
grains. As the filtering paper, upon which this residue has been col- 
lected, was coloured brownish, it was extracted with a little weak mu- 
riatic acid, and the solution treated with prussian alcali, which pro- 
duced a blue precipitate of iron. 
cl. Upon those 2J- grains of the brownish residuum nitric acid was 
poured and again driven off by heat, after which potassa was affused. 
This took up but a little, and the residuum, again washed and ignited, 
lost only of a grain. The alcaline fluid was neutralized with nitric 
acid, and one-half of it combined with acetated lead, the other half 
with nitrate of silver. By the lead a lemon-yellow, and by the silver 
a brown-red precipitate was obtained. Thus the portion of chrome 
in emerald was separated and obtained singly. 
e. The brown residue of d was dissolved in muriatic acid, but the 
solution, acted on by a low heat, soon coagulated into a jelly-like sub- 
stance, owing to the siliceous earth which separated, and upon ignition 
weighed J gr. The fluid, freed from this, was then treated with a so- 
lution of succinate of soda. The precipitate, obtained by this means, 
when edulcorated and dried, gave 1 grain of oxide of iron. 
f. As to the alcaline solution c, I mixed it with the remaining fluid of 
e, supersaturated the mixture with muriatic acid, and precipitated it in 
an ebullient heat with carbonated soda. The precipitate here obtain- 
ed I dissolved in sulphuric acid, and after having combined it with 
•acetate of potassa, forwarded it to crystallization. The first shootings 
yielded alum, in pure crystals ; but on subsequent evaporation sulphate 
of lime appeared, which, in the ignited state, weighed | of a grain, 
equivalent to \ of pure lime. What still remained of the fluid had 
now a thick oily consistence ; diluted with a little water, and exposed 
to spontaneous crystallization, it afforded crystals, but they had not the 
form of alum. 
g. This saline mass, together with the alum already obtained, was 
dissolved in water, and a large quantity of carbonate of ammonia af- 
fused, upon which I stoppered the vessel. After it had stood 24 hours, 
I separated the remaining earth by means of the filter, dissolved this 
last again in sulphuric acid, and, lastly, extracted it by adding a great 
over-proportion of carbonated ammonia. When the earth had again 
been separated, it was a second time subjected to the same treatment; 
after which nothing more was taken up by the ammonia. 402 
ANALYSIS OF 
h. The aluminous earth was now heated to redness ; it then amount- 
ed to 15£ grains. 
i. From the ammoniacal fluid, which had been collected from those 
reiterated extractions, the superabundant alcali was distilled off, until 
the quantity of the white earth, which parted from the fluid, no longer 
increased. This earth, washed and dried, weighed 231 grains ; after 
ignition its weight proved to be 12i grains. 
When re-dissolved in sulphuric acid, and left to spontaneous evapo- 
ration, it formed oblique, quadrilateral double pyramids, with trun- 
cated edges and corners. The saccharine taste of these crystals, 
in conjunction with their other properties, showed that the base of 
this salt was glucine, the new earth discovered by Vauquelin in the 
beryl. 
Hence this decomposed emerald has yielded, as its constituent 
parts, 
Silex 
. b 68 ) 
e 0.50$ ' ‘ 
. . . 68.50 
.Alumine . . . 
. h 
. . . 15.75 
Glucine . . . 
Lime 
•/ 
Oxide of iron 
. c 
... 1 
Oxide of chrome d 
98.30 
Section XXXVI. Of the Combuiations of Yttrium and lliorinum. 
1516. I have not been able to collect any information relative to the 
analysis of the compounds containing yttria, which would assist the 
student in their examination, in addition to that which has been given 
in the proceeding Chapter, where 1 have enumerated the distinctive 
characters of yttria, and the mode of separating it from its combination 
with other earths (1362). 
1517. Thorina, found by Berzelius in the Gadolinite of Koraruet, 
and in two other Swedish minerals, which he terms deuto-jiuate of ceri- 
um, and double fluate of cerium and yttria, has not hitherto been exa- 
mined by any other chemist; indeed, the discoverer has himself ob- 
tained it in such small quantities as to have enabled him to furnish but 
an imperfect account of its properties. In addition, therefore, to the 
distinctive characters of thorina given above (1364) I shall here only 
add the process by which it was procured. 
To the solution of the mineral add succinate of ammonia to throw 
down the iron ; then pour in sulphate of potassa to precipitate the 
cerium, and afterwards ammonia will separate the yttria and thorina; 
to separate these substances re-dissolve them in muriatic acid, and eva- 
porate till the solution is as nearly neutral as possible, then pour water 
upon it and boil for an instant; thorina is precipitated, and the liquid 
becomes acid : by saturating this acid, and boiling again, an additional 
portion of thorina precipitates. 
These details are, it must be confessed, very unsatisfactory: and MINERAL WATERS. 
when we reflect upon the complex nature of the substances submitted 
to analysis, upon the prolixity of the process, upon the small quantity 
of thorina hitherto procured (not amounting, according to Dr. Thom- 
son (System, i. 377, 6th Edit.) to 7 grains and a half,) and upon the 
acknowledgment that it is only occasionally present in the minerals ad- 
verted to, we may perhaps be inclined to doubt its distinct nature. 
CHAPTER VII. 
OF THE ANALYSIS OF MINERAL WATERS. 
1518. The following observations, relating to the analysis of mine 
ral waters, have been drawn up principally with a view to facilitate 
the progress of the student, in that very difficult department of ana- 
lytical chemistry. I have endeavoured to simplify the details by point- 
ing out the readiest methods of recognising and separating the sub- 
stances which usually occur, and have, therefore, omitted the enume- 
ration of the more rare ingredients, or of those which are limited to 
particular places. 
I have not adverted to the mode recommended by Dr. Murray 
(.Edinburgh Phil. Trans., viii.) because I cannot readily admit the exist- 
ence of incompatible salts to the extent which his principle requires ; 
nor do I think that it materially facilitates the analysis in those cases 
which present peculiar difficulties to the plan of determining the in- 
gredients by evaporation. 
Section I. Of the Tests and Apparatus required in the Examination 
and Analysis of Mineral Waters. 
1519. Those who have not access to a regular laboratory will find 
it convenient to arrange the following tests and re-agents in the manner 
represented in Plate III. of this work, the larger phials should con- 
tain about 6 ounces by measure ; the second size, 3 ounces ; and the 
smallest, 1 ounce. Of these phials, the greater number should be 
simply stopped, and a few of them provided with an elongated stopper 
dipping into the fluid which they contain. 
The larger phials may contain the following re-agents: 
Pure sulphuric acid. 
nitric acid. 
muriatic acid. 
Dilute sulphuric acid, 1 acid 4* 3 water, 
nitric acid ditto. 
muriatic acid . . . ditto. 
Solution of potassa. Solution of soda. 
ammonia. 
carbonate of potassa. 
carbonate of soda. 
• carbonate of ammonia. 
oxalic acid. 
Sxalate of ammonia. 
baryta. 
acetate of baryta. 
nitrate of baryta. 
phosphate of soda. 
sulphate of silver. 
Alcohol. 
ANALYSIS OF 
The smaller phials may contain 
Tincture of galls. 
Solution of iodine in alcohol. 
nitrate of silver. 
ferro-cyanate of potassa. 
muriate of lime. 
hydro-sulphuret of ammonia. 
hydriodate of potassa. 
soap in alcohol. 
Phosphorus. 
Sulphate of lime. 
Test-papers, turmeric, litmus, violet. 
Black flux. 
Nitrate of ammonia. 
The tray should contain a few Florence flasks (1), Wedgwood and 
glass basins (2, 3), a platinum and a silver crucible (4, 5), a silver cap- 
sule (6), some funnels (7), test-glasses (8), test-tubes (9), and glass rods, 
filtering paper, a spirit (10), and an Argand lamp (11), a retort (12), 
and receiver (13), a copper basin to serve as sand-bath (14), a blow- 
pipe (15), a thermometer (16), a scale of equivalents (17), a dropping- 
bottle (18), a few watch-glasses (19), a support for holding glasses over 
a lamp (20), a small brass stand with rings (21), a tube, with a bulb in 
the centre and a pointed extremity, for drawing up small portions of li- 
quids (23), platinum pincers (24, 25) ; a small but good balance, with 
well-adjusted weights, is also requisite, accompanied by a phial and 
counterpoise for taking specific gravities ; and, lastly, a small mercurial 
trough. There should also be a plentiful supply of distilled water, a 
portion of which should be contained in a dropping-bottle. 
Section II. Examination of Mineral Waters by Tests. 
1520. i. The term mineral water is applied to those natural spring' 
waters which contain so large a proportion of foreign matter as to ren- 
der them unfit for common domestic use, and to confer upon them a MINERAL WATERS. 
sensible flavour, and specific action upon the animal frame. Their 
temperature is liable to considerable variation, and is sometimes their 
principal character, as is the case with the waters of Bath and Buxton ; 
but they are generally so far impregnated with acid or saline bodies, 
as to derive from them their peculiarities, and in this respect may con- 
veniently be arranged under the heads of carbonated, sulphureous, sa- 
line and chalybeate waters. See the annexed Table (1522.) The mere 
taste of the water enables us to determine to which of these subdivi- 
sions it probably belongs. 
ii. In examining a mineral water, it is of importance to ascertain 
its specific gravity , which gives us some insight into the proportion of 
its saline ingredients, its specific wreight, as compared with pure water, 
being of course augmented by its foreign contents. Mr. Kirwan (Es- 
say on Mineral Waters, p. 145.) has given the following formula for 
calculating the proportion of saline substances in a water of known 
specific gravity : “ subtract the specific gravity of pure water from 
that of the water examined, and multiply the remainder by 1.4. The 
product is equal to the saline contents in a quantity of the water denot- 
ed by the number employed to indicate the specific gravity of distilled, 
water. Thus suppose the specific gravity of the water = 1.079, and 
that of pure water = 1.000, then 79 X 1.4 = 110.6 = saline contents 
in 1000 of the mineral water.” 
This is a useful formula, but open to certain objections ; and as it is 
often of considerable importance to acquire a just knowledge of the 
proportion of foreign bodies in water, it is advisable to conjoin the 
above method with the following: 
iii. Evaporate a given weight, say 1000 parts, to dryness, and ex- 
pose the residue for 24 hours to a temperature not exceeding 300® 
upon a platinum capsule ; weigh it while warm, and the mean obtain- 
ed from this and the former experiment, will give the proportion 
of dry saline ingredients within an error of two per cent. Thus sup- 
pose 1000 parts of the above-mentioned water give by evaporation 
114.4 dry residue, then 110.6 + 114.4 = 225 ■— 2 = 112.5= quan- 
tity of saline matter in a dry state (salts deprived of water of 
lization) existing in the mineral water under investigation. 
iv. Having by these preliminary operations ascertained the relative 
quantity of foreign matter in the water under examination, the nature 
of the substances present is next to be inquired into. 
1521. The substances which have been found in mineral waters are 
extremely numerous, but those which ordinarily occur, are the fol- 
lowing : 
Oxygen. 
Nitrogen. 
Carbonic acid. 
Sulphuretted hydrogen. 
Carbonate of lime. 
Carbonate of magnesia, 
Carbonate of iron. 
Muriate of magnesia. 
Sea salt. 
Sulphate of magnesia. 
Sulphate of soda. 
Sulphate of lime, ANALYSIS OF 
«. Oxygen and nitrogen exist in the greater number of spring waters 
in the proportions constituting atmospheric air ; the proportion of ni- 
trogen is, however, not unfrequently predominant. These gases give 
no peculiar flavour to the water. 
b. Carbonic acid renders mineral waters sparkling and effervescent: 
it is detected by occasioning a precipitate in aqueous solution of bary- 
ta, which dissolves with effervescence in dilute muriatic acid. 
c. The presence of sulphuretted hydrogen is known by its peculiar 
disagreeable smell; by the production of a black precipitate on drop- 
ping into the water a solution of nitrate of silver ; and by the deposition 
of sulphur on adding a few drops of nitric acid. 
d. The carbonates are dissolved in the water by excess of carbonic 
acid, and consequently fall upon its expulsion by boiling. Carbonate 
of lime and magnesia are deposited in the form of a white precipitate. 
Carbonate of iron occasions the separation of a rusty brown ferruginous 
powder, and the water is blackened by a few drops of tincture of galls. 
e. Mr. R. Phillips, in his analysis of Bath waters, has shown that the 
delicacy of galls, as a test for iron, is curiously affected by the pre- 
sence of certain salts : if the iron be in the state of protoxide, its de- 
tection is facilitated by salts with a base of lime, and by alcalis ; if in 
the state of peroxide, lime prevents the action of the test. This is 
well shown by dissolving a very minute portion of protosulphate of iron 
in a glass of distilled water, and adding a drop of tincture of galls, which 
occasions no immediate discoloration ; but a drop of lime-water, or 
other alcali, instantly renders the presence of iron evident; so that 
the quantity of iron present in a water cannot be correctly judged of by 
the degree of precipitation occasioned in it by tincture of galls. 
f. Ferro-cyanate of potassa is also a good test to show minute quan- 
tities of iron in water, by the blue precipitate which it occasions ; its 
action is aided by previously adding two or three drops of nitric acid 
to the water ; but it is an equivocal test compared with galls. 
g. The presence of muriatic salts and of chlorides, is indicated by a 
white cloud on adding sulphate of silver. 
h. The sulphates, when present in water, afford a white precipitate 
on the addition of nitrate of baryta, which is insoluble in nitric acid. 
i. Lime is recognised by a white cloud on dropping oxalate of am- 
monia into the water. A portion of the precipitate collected upon leaf 
platinum, and heated before the blow-pipe, may be burned into quick- 
lime. 
k. Magnesia is rendered evident by adding carbonate of ammonia 
which throws down the lime, and subsequently pouring in phosphate 
®f soda, which, when magnesia is present, carries a portion of it dowTn in 
the form of a granular precipitate of ammoniaco-magnesian phosphate. 
Such are the readiest means of recognising the presence of the va- 
rious substances that commonly occur, by the action of rfe-agents or 
tests ; and, having gained such general information, we next proceed 
to the analysis of the water, in order to ascertain the relative propor- 
tions of thq gaseous and saline ingredients which it holds dissolved. MINERAL WATERS. 
Section III. Analysis of Mineral Waters. 
1522. v. To ascertain the relative proportions of the gaseous con- 
tents of water with perfect accuracy, is a very difficult undertaking, 
and rarely necessary ; the following method is sufficiently precise in 
all ordinary cases of analysis. Provide a Florence flask capable of 
holding rather more than a measured wine-pint, which quantity of the 
water under examination is to be introduced into it, and a cork careful- 
ly fitted to its neck, through a perforation in which is inserted a glass 
tube one-eighth inch diameter, rising perpendicularly about 18 inches, 
and then bent so as to pass conveniently under the shelf of the mercu- 
rio-pneumatic apparatus. (Where a sufficiency of mercury cannot be 
procured, warm water may be substituted, if only carbonic acid be pre- 
sent, and it may be absorbed by transferring the jar containing it to a 
solution of potassa.) The flask should be placed over an argand lamp, 
and heat gradually applied till the water fully boils. The gas evolved 
is to be collected in the usual way, in a graduated jar over quicksilver, 
and submitted to the following examination :— 
vi. Throw up a small quantity of solution of potassa, which, if car- 
bonic acid be present, will absorb it, and the quantity will be shown by 
the diminution of bulk. 
vii. Introduce the remaining air, or a portion of it, into a small bent 
tube, containing a bit of phosphorus ; heat it so as to kindle the phos- 
phorus, and note the diminution of bulk when cold. It is proportion- 
al to the oxygen present, and if equal to one-fifth of the whole bulk, 
the gas may be regarded as atmospheric air*. 
viii. If sulphuretted hydrogen be present it may be separated by 
strong alcoholic solution of iodine, which rapidly absorbs it, and scarce- 
ly takes up more than its own volume of carbonic acid gas. Chlorine, 
added to a mixture of sulphuretted hydrogen and carbonic acid, will 
also produce the absorption of the former if a little water be present; 
but it cannot be conveniently used over mercury. 
ix. During the ebullition it not unfrequently happens that a precipi- 
tation ensues, indicating that the substances thrown down were dis- 
solved by carbonic acid; and in that case they should be separated 
upon a filter a, after which the remaining water may be evaporated to 
dryness in a glazed porcelain basin ; the dry residue transferred to a 
silver capsule, and perfectly desiccated at a temperature not exceeding 
500°. b. 
The precipitate a may consist of carbonate of lime, of carbonate of 
magnesia, or of oxide of iron ; or it may be a mixture of the three ; 
dissolve it in dilute muriatic acid, and add oxalic acid which throws 
down oxalate of lime ; separate this by filtration, and saturate the fil- 
trated portion with carbonate of ammonia, which precipitates the per- 
oxide of iron, and having removed this, evaporate the residuary mix- 
ture, and expose the dry salt to a red heat in a small platinum capsule ; 
* In separating oxygen a solution of nitric oxide in protosulphate of iron may sometimes 
conveniently be employed, but it does not give so accurate a result as the action of phospho- 
rus. 408 
ANALYSIS OF 
the magnesia, if any were present, will remain ; if not there will be 
no residue, for the oxalic acid and muriate of ammonia will be destroy- 
ed and volatilized. 
100 parts of oxalate of lime indicate 77 of carbonate of lime. 
100 parts of red oxide of iron indicate 90 of black oxide, or 143 of 
carbonate of iron. When carbonic acid holds iron in solution, the 
metal is in the state of protoxide, and if air be excluded, it requires 
long boiling to decompose it ; for the same reason, if the water be ex- 
posed, under the exhausted receiver of the air-pump, it does not rea- 
dily become brown, as is the case when it is exposed to air ; a drop or 
two of nitric acid facilitates the deposition of the red oxide. 
100 parts of pure magnesia are equivalent to 213 of carbonate of 
magnesia. 
x. The dry residue b, is to be digested in six or eight parts boiling 
alcohol, specific gravity 0.817, which will take up muriate of magne- 
sia, and in some rare cases (where no sulphates are present) muriate 
of lime. Filter off the alcoholic solution, and wash the residue c 
with a little fresh alcohol, which add to the former, and evaporate to 
dryness r>. The dry mass n, exposed for some time to a heat of 500°, 
is generally pure muriate of magnesia ; if it contain muriate of lime, 
the latter earth may be separated by solution of oxalic acid, in the 
state of oxalate of lime. 
I have found it, in some cases, convenient to convert the muriates of 
lime and magnesia into sulphates, by pouring upon them excess of sul- 
phuric acid, evaporating to dryness, and heating the dry mass red hot. 
The sulphate of magnesia may then be almost completely separated 
from the sulphate of lime, by a small quantity of cold water ; or a sa- 
turated solution of sulphate of lime may be used, which takes up the 
sulphate of magnesia, and, of course, leaves the sulphate of lime. 
The alcohol will also take up a very minute portion of sea-salt, 
which, however, is too small to require estimation 
xi. The residue c, insoluble in alcohol, may contain sea-salt, sul- 
phate of soda, sulphate of magnesia, and sulphate of lime ; digest it in 
ten parts of boiling distilled water, which, w-hen cold, will have taken 
lip every thing but sulphate of lime, of which an inappreciable por- 
tion only will have been dissolved ; separate the solution into two 
equal portions, a and b. 
To a add nitrate of silver, and wash and dry the precipitate, which 
is chloride of silver, and of which 100 parts indicate 41 of sea-salt. 
To & add acetate of baryta as long as it occasions a precipitate, which 
is sulphate of baryta, and which is to be separated, dried and weighed. 
100 grains are equivalent to GO.5 of sulphate of soda, and to 51 of sul- 
phate of magnesia. 
In order to ascertain the quantity of magnesia present, and conse- 
quently the quantity of sulphuric acid belonging to it, evaporate the 
liquid filtered off the barytic precipitate e to dryness ; it will contain 
sea-salt, acetate of soda, acetate of magnesia, and, probably, a portion 
of the added acetate of baryta ; ignite the dry mass, and wash it to se- 
parate the sea-salt and soda ; magnesia and carbonate of baryta will 
remain insoluble, upon which pour dilute sulphuric acid ; digest, filter, 
and evaporate the clear liquor to dryness ; it is sulphate of magnesia, 
equivalent of course to the original portion of the salt ; deduct the 
sulphuric acid contained in it from the whole in the precipitate f,, and 
the remainder will give the quantity united to the soda. MINERAL WATERS. 
Xii. To estimate the quantity of sulphate of lime in the water, the 
residue of the evaporation of one point may be washed with cold sa- 
turated solution of sulphate of lime, which will dissolve every thing 
but that sulphate, and which may thus be obtained and weighed ; or, 
add oxalate of ammonia to a given quantity of the boiled and filtered 
water, collect the precipitate, and dry it at a heat of 500°. 100 grains 
of this oxalate indicate 104 of dry sulphate of lime. 
xiii. Such are the general components of mineral waters, and the 
means of ascertaining their relative quantities. Let us suppose the 
following results have been obtained, with a view to illustrate the mode 
of drawing up the analysis. By the process v, twelve cubical inches 
of gas have been expelled during the ebullition of a pint of water. 
The exposure to solution of potassa has occasioned a diminution of 
eleven cubical inches, which, it. having been previously ascertained 
that no sulphuretted hydrogen was present, may be considered as car- 
bonic acid. The remaining gas thrown up into a tube containing a por- 
tion of phosphorus, and heated, suffers scarcely any diminution, and 
the phosphorus does not burn : hence it may be regarded as nitrogen. 
The gaseous contents, therefore, of the water under examination are 
in the wine-pint— 
Carbonic acid . . . 
Nitrogen 
If sulphuretted hydrogen be present, it is best to have recourse to a 
separate operation to estimate its quantity: for this purpose collect 
the gas as before, and throw up into it a small quantity of alcoholic 
solution of iodine. The absorption denotes the quantity of the gas. 
(viii.) 
xiv. The next step of the operation relates to the examination of 
the precipitate deposited during ebullition, (ix. a.) Let us suppose 
the weight of oxalate of lime to be 3 grains, of oxide of iron 1.5 
grain, and of magnesia 1 grain ; then the above data give 
Grains. 
Carbonate of lime 
2.2 
Carbonate of iron 
2.4 
Carbonate of magnesia 
2.1 
xv. The alcoholic solution (x.) may be diluted with water and test- 
ed by oxalic acid for lime ; if absent, evaporate to dryness as directed. 
Let us suppose the residue to be 
Muriate of magnesia 5 grains. 
If the quantity of muriate of magnesia be considerable, greater ac- 
curacy is ensured by converting it into sulphate, which is done by 
placing it in a capsule of platinum, pouring upon it sulphuric acid, eva- 
porating to dryness, and heating the dry mass to dull redness. 100 
grains of this dry sulphate of magnesia indicate 94 of muriate of mag- 
nesia ; hence the water under examination would have given 5.35 grains 
=5 grains of muriate. 
* Of this nitrogen, a small portion will probably have been derived from the air in the tube 
connecting the flask with the pneumatic apparatus; a little practice soon enables the operatoi 
to ascertain when it has been expelled; or itmay be received entire, and afterwards deducted 
from the whole produce. analysis of 
If the alcoholic solution contain muriate of lime, that earth must be 
previously separated by oxalic acid ; and 100 parts of oxalate of lime 
are equivalent to 85 of dry muriate of lime. 
xvi. The aqueous solution of the residue (c xi.) being divided into 
two portions, let us suppose the portion a xi. to afford 8.5 of chloride 
of silver, which indicates of sea-salt 3.5 grains = 7 grains in the pint. 
xvii. Let us assume, that the precipitate of sulphate of baryta b xi. 
weighs 15 grains, indicating of 
Sulphuric acid 5.1 grains. 
The process directed in xi. furnishes of 
Sulphate of magnesia .... 3.76 grains, 
which contain 2.5 grains of sulphuric acid, and which deducted from 
5.1 grains leave 2 6 grains, which are adequate to the formation of 
Sulphate of soda 4.65 grains. 
So that the pint (the water having been divided into two equal portions) 
would contain of 
Sulphate of magnesia 3.75X2=7.5 grains. 
Sulphate of soda . . 4.65X2=9.3 grains. 
xviii. The addition of oxalate of ammonia, or oxalic acid, to a pint 
of the boiled water (xii.) furnishes a precipitate of 4.7 grains of oxa- 
late of lime, indicating of 
Sulphate of lime 5 grains. 
xix. To give a general view7, therefore, of the components of the 
mineral water which has thus been examined, we should place them as 
follows:— 
One wine pint contains 
Cubic Inches. 
Carbonic acid 
Nitrogen 
1 
Gaseous contents 
Grains. 
Carbonate of lime 
. . . . 2.20 
Carbonate of iron 
. . . 2.40 
Carbonate of magnesia 
Muriate of magnesia 
, . . . 5.00 
Sea salt 
. . . 7.00 
Sulphate of magnesia 
. . . 7.50 
Sulphate of soda 
Sulphate of lime 
... 5. 
Aggregate weight of solid contents 
40.50 
xx. Besides the substances now enumerated, and which may be con- 
sidered as the most frequently occurring ingredients in mineral waters, 
there are others occasionally present, of which the following is an 
enumeration, with the best methods of detecting them: 
a. Carbonate of soda is known to exist in water, when, after having 
been boiled down to half its bulk, and, if necessary, filtered, it reddens 
tumeric paper, and restores the blue of litmus reddened by vinegar; 
it also affords an effervescent precipitate with nitrate of baryta, soluble 
in dilute nitric acid. This carbonate is incompatible with the soluble 
salts of lime. mineral waters. 
411 
Muriate of lime may also be used to detect the alcaline carbonates, 
with which it affords a precipitate of carbonate of lime. Carbonate of 
soda is distinguished from that of potassa, by the latter affording a pre- 
cipitate in neutral muriate of platinum, which the former does not. 
Carbonate of ammonia is obviously discoverable by its smell, when 
acted on by caustic fixed alcali or lime. 
b. Silica is detected by evaporating the water to dryness, and boil- 
ing the residue in dilute muriatic acid. The silica, if present, remains 
as a white powder not altered by a red heat, but instantly fusing with a 
particle of carbonate of soda. 
c. Boracic acid and borax have been found in certain lakes in India, 
and in some parts of Italy. To detect boracic acid, evaporate to one- 
eighth the original bulk of the water, and add carbonate of soda as long 
as it occasions any precipitate ; boil and filter. The filtered liquor will 
contain borate of soda, with some other salts of the same basis ; eva- 
porate to dryness in a platinum crucible, and digest the residue in three 
or four parts of sulphuric acid, diluted with its bulk of water. ' If bo- 
racic acid be present, it will separate in micaceous crystals. 
d. Alumina has been found in a few mineral waters in the state of a 
sulphate. It may be separated by the following process : Evaporate to 
dryness, digest in alcohol, and re-dissolve the residue in eight parts of 
water ; filter and add oxalic acid, which throws down lime, and which 
being separated, leaves magnesia and alumina in solution. Carbonate 
of ammonia throws down the alumina and leaves the magnesia. 
Pure ammonia throws down both alumina and magnesia. These 
earths may be separated by solution of potassa, which dissolves the 
former but not the latter. 
e. Manganese is sometimes found in water, but only in very small 
proportion, so as not to amount to more than a trace. Dr. Scudamore 
found a trace of manganese in the waters of Tunbridge Wells, and it 
has never been discovered in larger proportion. 
/. It has been said that certain nitrates are occasionally present in 
water, but such solutions can scarcely be called mineral waters. If 
nitrate of lime be present, it will be taken up from the residue of eva- 
poration by alcohol, and may be decomposed by carbonate of potassa, 
so as to afford carbonate of lime and crystals of nitre. 
g. It sometimes happens that water contains lead, which may be de- 
tected by evaporation to one-eighth its bulk, adding a few drops of ni- 
tric acid, and then hydriodate of potassa, which gives a yellow insolu- 
ble precipitate ; and hydrosulphuret of ammonia, whieh forms a deep 
brown or black cloud. These precipitates may be reduced by heating 
them before the blow-pipe upon charcoal, mixed with a little black flux. 
h. If vegetable or animal matter be contained in water, it gives it a 
brown colour, especially when evaporated. It may be destroyed in 
the dry residue by igniting it with a small addition of nitrate of ammo- 
nia. 
The following analyses of mineral waters may be advantageously 
consulted by \he student, as containing a variety of useful details, which 
are necessarily omitted in the above observations :—Analysis of the Hot 
Springs at Bath, by Richard Phillips, Esq. Analysis of the Brighton 
Chalybeate, by Dr. Marcet. Analysis of the Tunbridge Wells Waters, 
by Dr. Scudamore. Mr. Children’s Translation of Thenard’s Essay 
on Chemical Analysis, chap vi. COMPOSITION Of MINERAL WATERS. 
WATERS 
GASES 
CARBONATES 
SULPHATES ) MURIATES 
Oxide 
of 
Iron 
Silica 
Tempe- 
rature 
Total 
of 
Saline 
Con- 
tents 
AUTHORITY 
Nitrogen 
c.,. 
Carbonic 
Acid, 
C. I. 
Sulphu- 
retted 
Hydrogen 
C. I. 
Carbo- 
nate 
of Soda, 
grains 
Carbo- 
nate of 
Magnesia 
.grains 
Carbo- 
nate 
of Lime, 
grains 
Sulphate 
of Soda, 
grains 
Sulphate 
of 
Magnesia 
grains 
Sulphate 
of Lime, 
grains 
Muriate 
of Soda, 
grains 
Muriate 
of 
Magnesia 
grains 
Muriate 
of 
Lime 
CARBONATED 
' Seltzer 
17. 
4. 
5. 
3. 
17. 
Cold 
29. 
Bergman. 
Pyrmont 
26. 
10. 
4.5 
5.5 
8.5 
1.5 
0.6 
do. 
30.0 
Ditto. 
Sp* 
....... 
13. 
1.5 
4.5 
1.5 
0.2 
0.6 
do. 
8.3 
Ditto. 
Carlsbad 
5. 
5. 
1.5 
8.5 
4.5 
a trace 
0.3 
165° 
19.8 
Klaproth. 
Pouges .. 
30. 
10. 
1.2 
12. 
2.2 
2.5 
0.5 
Cold 
28.4 
Hassenfratz. 
Saint Parizp 
22. 
0.5 
11.5 
13. | ...... 
do. 
25. 
Ditto.- 
in 
u> 
, o 
-jS 
D * 
£> 
8 
& 
' Harrogate 
0.8 
1. 
2.3 
0.7 
2.5 
1.3 
77. 
ii. 
1.5 
do. 
94. 
Garnet. 
Moffatt 
0.5 
0.6 
1.2 
4.5 
do. 
4.5 
Ditto. 
Aix-la-Chapelle 
5.5 
12. 
4.2 
5. 
143° 
21.2 
Bergman. 
Cheltenham Sulphur Spring... 
1.5 
2.5 
23.5 
5.1*7- 
1.2 
35. 
0.3 
Cold 
65. 
Parke* U Brande. 
SALINE 
Seidlitz 
1 2-5 
0.8 
180. 
5. 
4.5 
do. 
192.8 
Bergman. 
Cheltenham pure Saline 
15. 
11. 
4.5 
50. 
do. 
80.5 
Parkes &. Brande. 
Bristol 
3.5 
1.5 
1.5 
1.5 
0.5 
1. 
74° 
6. 
Carricb. 
Buxton 
0.2 
1.3 
0.3 
0.2 
0.03 
82° 
1.83 
Pearson. 
Bath 
1.2 
0.8 
1.5 
9. 
3.3 
a trace 
0.2 
116° 
14.6 
Phillips. 
Scarborough 
a trace 
20. 
9. 
ditto 
Cold 
2.9 
Saunders. 
Barege 
uncertain 
2.5 
ditto 
a trace 
0.5 
120 
3. 
Ditto. 
Plomhierea 
2.2 
, 0.3 
2.3 
1.5 
0.3 
? 
66. 
Vauquelin. 
Kilbum.... 
3.5 
.8.5 ? 
0.5 
1. 
12. 
37. 
5.5 
2.5 
5.5 
0.2 
a trace 
Cold 
64.2 
Schmeisser. 
Leamington New Rath 
0.4 
a trace 
a trace 
19. 
14. 
53. 
1.5 
0.8 
do. 
88.3 
Lambe. 
Leamington Old Bath.. 
0.3 
ditto 
V 7.5 
7. 
18. 
41. 
do. 
73.5 
Ditto. 
M 
■lb 
Tunbridge T. 
0.59 
s 
a trace of 
oxygen 
! 
0.03 
m 
0.17 
0.30 
0.03 
0.05 
0.28 
do. 
0.56 
Scudamore. 
Cheltenham Chalybeate 
. 2-5 
0.5 
22.7 
6. 
2.5 
41.3 
0.8 
do. 
73.8 
Parkes &. Brande. 
Brighton 
«• 2.2 
4. 
3. 
0.75 
1.4 
0.14 
do. 
9.29 
Marcet. 
1523. TABULAR VIEW OF THE COMPOSITION OF MINERAL WATERS. 
One Pint (Wine Measure) contains the following ingredients: TABLE OP EQUIVALENTS. 
SUBSTANCES 
Specific 
Equivalent 
COMPOSITION 
REMARKS 
Gravity 
N umber 
0.85 
40 
The following characters belong to the 
Salts of Potassium: they are all so- 
protoxide, or dry potassa 
2.5 
48 
40 P. + 8 oxygen. 
luble in water, and afford no precipi- 
tates with pure or carbonated alca- 
1.7 
57. 
48 Ox. Potassium -f 9 water. 
lis; they produce a precipitate in 
muriate of plantinum, which is a 
64 
40. P. + 24 oxygen. 
triple compound of potassa, oxide 
of platinum, and muriatic acid. 
76 
40. P.+36 C. 
They are not changed by sulphurel- 
ted hydrogen, nor by terrocyanate 
of potassa. Added to sulphate of 
124 
48 O. P. + 76 C. A. 
alumina, they enable it to crystallize 
140 
48 0. P. -f. 92 oxych. a. 
40. P. +125 
48 0. P.-j-126 H. A. 
48 0. P. + 1G5. iod. a. 
40 P. 4-1 Hydro. ? 
so as to form octoedral alum. 
165. 
174 
218 
41 
TABULAR VIEW of Specific Gravities and Equivalent Numbers of the Metals and their 
Combinations. TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
1.99 
102 
56. 
72 
80 
88 
128 
145 
52 
68 
76 
124 
48 0. P. +54. N. A. 
40P. + 16 S. 
48 G. P. -f-24 Hyp. S. A. 
48 0. P. + 32S. A. 
48 0. P.+40S. A. 
48 0. P. + 80 S. A. 
48 0. P.+80 S. A.4-17 A. 
40 P. 12 Phos. 
48 0. P. 4- 20 P. A. 
48 0. P.4-28P. A. 
96 0. P. 4*28 P. A. 
sulphite 
2.4 
bisulphate 
ammonio-sulphate 
phosphuret 
hypophosphite ? 
phosphite 
phosphate 
subphosphate 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, fyc. 
SUBSTANCES 
Specific 
Gravity. 
Equivalent 
Number 
COMPOSITION 
REMARKS 
104 
48 0. P.+56 P.A. 
u * 
70 
dan p xwn a 
2.01 
92 
48 0. P.+44C. A. 
— cyanuret 
hydrocyanate 
70 
48 O. P. + 22B.A. 
0.9 
24 
All the Salts of Soda are soluble in 
1. oxide 
32 
24 S. + 8 O. 
water; they are not precipitated by 
pure or carbonated alcalis, nor by 
hydrated 
41 
32 0. S. + 9W. 
hydrosulphuret of ammonia, nor fer- 
rocyanate of potassa; nor do they 
peroxide 
36 
24S.+.12 0X. 
produce any precipitate in solution 
of muriate of platinum. They do 
chloride 
60 
24S. + 36 C. 
not convert sulphate of alumina into 
octoedral alum. 
chlorate 
108 
32 0. S. + 76C. A. 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
Sodium, oxychlorate 
124. 
32 0. S.+92 Oxy. C. A. 
■——— iodide 
149. 
24 S. -J-125 
197 
S2 o S +165 O A 
158 
32 0 S +126 H A 
nitrate 
2.09 
86 
32 0. S. + 54 N. A. 
sulphuret 
40 
24 S. + 16 Sul. 
hyposulphite 
56 
32 0. S. + 24 Hyp. S. A. 
64 
<*2 0 s +32 S A 
72 
-+40 S A 
162 
79 CJ q J.9D Water 
■ bisulphate 
112 
32 0. S. + 80 S. A. 
- ammonio sulphate 
129 
32 0. S.+ 80 S.A.+ 17Am. 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, &C. 
417 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
36 
24 S.+12 P. 
52 
32 0. S.+20 P. A. 
60 
32 0. S.+28 P. A. 
■— • biphosphate 
88 
32 0. S.+56 P. A. 
— - ammonio-phosphate 
105 
32 0. S.+56 P. A.+I7 Am. 
carbonate 
1.35 
54 
32 0. S.+22 C. A. 
76. 
32 0. S.+44 C. A. 
—■— cyanuret 
•A 
— ■ hydrocyanate 
borate, or borax 
1.74 
III. Lithium 
9.8? 
Lithia is distinguished from petassa and 
soda, by its high saturating power, by 
17.8 
9.8 L.+8 0. 
the difficult solubility of its carbonate, 
by the deliquescency and ready jsoii;- 
Metals and their Combinations (continued.) 418 
tabular view of 
SUBSTANCES 
i 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
I 
45.8 
93.8 
71.8 
57.8 
45.8 
39.8 
20 
28 
37 
56 
65 
9.8 L+36 C. 
17.8 0. L. + 76. chi. ac. 
17.8 0. L. + 54. N.A. 
17.8 0. L. +40. S. A. 
17.8 0. L. +28 P. A. 
17.8 0. L.+22. C. A. 
20C + 8O. 
28 0. C.+9 W. 
20C.+36 C. 
28 0. C.+37 M. A. 
bility of its chloride, and by the charac- 
ters of its sulphate. 
The Salts of Lime furnish precipitates 
of carbonate of lime by the car- 
bonated alcalis; they afford no pre- 
cipitate with caustic ammonia. Ox- 
alic acid, and oxalate of ammonia, 
produce precipitates of oxalate of 
lime, which, at a red heat, affords 
quicklime. 
1,5 
— oxymuriate ? 
Metals and their Combinations (continued.) equivalent numbers, fyc. 
419 
SUBSTANCES. 
1 
1 
Specific 1 
Gravity | 
1 
Equivalent 
Number 
| 
COMPOSITION. 
REMARKS 
104 
28 0. C.-f 76 C. A. 
14S 
20 C. + 125 I 
193 
28 0. C. + 165 0. A. 
— — hydriodate 
154 
28 0. C. + 126H. A. 
1.6 
82 
28 0. C. + 54 N. A. 
——— sulphuret 
36 
20 C.+16 S. 
■ — ■ " ■ hyposulphite 
52 
28 0. C.+24 hyp. S. A. 
—' sulphite 
60 
28 0. C.+32 S. A. 
68 
28 O. C 4-40 S. 
crystallized 
86 
68 dry sulphate-f-18 water 
32 
20 c. 4.12 P. 
phosphate .. . 
56 
28 0. C. 4-28 P. A. 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Numbers 
1 
COMPOSITION 
1 
R® MARKS 
1 
84 
50 
50 
36 
17 
22 
to hydrogen 
70 
78 
87 
106 
1 Cd 
28 O. C. + 56P. A. 
28 0. C. + 22 C. A. 
28 0. C.+22B. A. 
20 C. +16 Fluorine? 
16 Fluorine+1 hydrogen 
16 F.+6 B. 
23.71 to atmospheric air. 
70 B.+8 O. 
78 0. B.+9W. 
70 B.+ 36 C. 
wn r c r a 
The Soluble Barytic Salts furnish white 
precipitates of carbonate of baryta, 
by the alcaline carbonates. Sulphu- 
ric acid and the soluble sulphates oc- 
casion white precipitates of sulphate 
of baryta in the solutions of the earth. 
They are poisonous, and tinge flame 
yellow. 
2.7 
3. 
Fluoboric gas j 
32.68 
— 
Metals and their Combinations (continued.) TABLE OF EQUIVALENTS. 
421 
SUBSTANCES 
Specific 
Gravity . 
Equivalent 
Number 
COMPOSITION 
REMARKS 
£ 
195 
70 B. + 125 I. 
' 
243 
78 O. B. +165 I. A. 
204 
78 O. B.+126H. A. 
** 4. 
132 
78 0. B. +54 N. A. 
86 
70B. + 16S. 
102 
78 0. B. +24 hyp. S. A. 
110 
78 0. B- +32 S. A. 
4.4 
118 
78 0. B.+40S. A. 
82 
70B.+12P. 
98 
78 0. B. +20 P. A. 
phosphate 
1.28 
106 
78 0. B. +28 P. A. 
carbonate 
4.2 
100 
78 0. B. +22 C. A. 
Metals and their Combinations (continued.) 422 
TABULAR VIEW Of 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
Barium, borate 
100 
78 0. B.+22B. A, 
44 
The Salts of Strontium furnish white 
precipitates with the alcaline carbon- 
52 
44S. + 8 0. 
ates, and with sulphuric acid and 
sulphates; they tin ye flame of a fine 
61 
52 0. S.+ 9 W, 
red: they are not poisonous. They 
are decomposed by baryta, which has 
AA <5 -L Sfi f! 
strontia; they are more soluble than 
128 
52 0. S.+76 C. A. 
barytic salts, but pure strontia is less 
soluble than baryta. 
89 
j;2 0 S + 37M. A. 
169 
44 S +125 T 
■ 217 
52 O S.+ 16.5. T A 
106 
.52 O S +54 N A 
sulphuret 
60 
44 S.+16 Sul. 
hyposulphite 
76 
52 0. S. +24 Hyp. S. A. 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, &<?. 
423 
SUBSTANCES 
Specific 
Gravity. 
Equivalent 
Number 
COMPOSITION 
REMARKS 
84 
52 0. S.-J-32 S.A. 
3.9 
92 
52 0. S. + 40 S. A. 
■ - ■ — ■ ■ phosphate 
80 
52 0. S. + 28 P. A. 
- - carbonate 
3.6 
74 
52 0. S.+22C. A. 
74 
52 0. S.+22 B. A. 
12 
by solution of potassa, and by its 
- ■ oxide 
2.3 
20 
12 M.+8 0. 
carbonate; the precipitate does not 
re-dissolve in excess of the alcalis, 
29 
20 0. M.+9 W. 
phuric acid. The salts of magnesia 
48 
, 12 M. +36 C. 
bicarbonate of potassa (cold), nor 
57 
20 0. M. + 37 M. A. 
be. applied, carbonic acid escapes, 
96 
20 0. M. -f- 76 C. A. 
state of carbonate. The salts rf mag- 
— ■ hydriodate 
146 
20 0. M. + 126H. A. 
nesia are only partially decomposed 
Metals and their Combinations (continued.) 424 
TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
Magnesium, nitrate 
74 
145 
44 
52 
60 
123 
117 
148 
48 
76 
93 
20 O. M. +54. N. A. 
20 0. M. +108 N. A. +17 Am. 
20 0. .M+24 Hypo. S. A. 
20 0. M. + 32S. A. 
20 0. M.+40 S. A. 
60 S. M. + 63 water 
20 0. M.+80 S. A.+ 17 amm. 
20 0. M. + 80 S. A. +48 potassa 
20 0. M. + 28 P. A. 
20 0. M. + 56 P. A. 
20 0. M.+56 P. A. +17 amm. 
by ammonia, which forms triple salts 
with the earth and acid. Oxalate of 
ammonia does not precipitate mag- 
nesia. 
• 
1.66 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, fyc. 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
42 
20 0. M.+22 C. A 
64 
20 0. M.+44C. A 
42 
20 0. M.+22 B. A. 
VIII. Manganese .. 
6.85 
28 
The Salts of Manganese are not preci- 
pitated by hydriodic acid. They 
■ ■ ■■ 1. oxide 
36 
28 M.+8 0. 
furnish white precipitates with the 
alcalis, which blacken by exposure 
2. oxide. 
40 
28 M.+12 0. 
to air. They are precipitated white 
by ferrocyanate of potassa, and yel- 
peroxide 
44 
28 M. +16 0. 
low by hydrosulphuret of ammonia. 
64 
28 M. + 36 C. 
90 
36 0.M.+54N. A. 
1 sulphuret 
hyposulphite 
60 
36 0. M.-{-24 hyp. S. A. 
sulphate 
76 
36 0. M.+40 S. A. 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
1 
Specific 
Gravity 
Equivalent 
Number 
1 
COMPOSITION 
REMARKS 
1 
Manganese, red sulphate? 
40 
64 
58 
28 
36 
40 
64 
82 
73 
95.5 
28 M+12 P. 
36 0. M.+28 P. A. 
36 0. M. + 22C. A. 
28 I. +8 0. 
28 I.+ 12. 0. 
28 1 + 36 C. 
28 I.+54 C. 
36 0.1.+37 M. A. 
40 0.1.+55.5 M. A. 
The Solutions of Iron are known by af- 
fording a purple or black precipitate 
to infusion of galls, which is an ex- 
tremely delicate test of the presence 
of the metal, provided any earthy oi 
alcaline salt be present. They give 
no precipitate with hydriodic acid. 
IX. Iron 
7.78 
chlorate 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, fyc. 
SUBSTANCES. 
1 
Specific 
Gravity 
1 
Equivalent 
Number 
COMPOSITION. 
REMARKS 
Iron, iodide 
153 
28 I.+125 Iod. 
The pure salts containing- the black 
oxide give a white or very pale blue 
protonitrate 
90 
36 0. I.+54 N. A. 
precipitate with ferrocyanate of po- 
tassa; while those containing the 
pernitrate 
121 
40 0.1.+ 81 N. A. 
brown oxide furnish a dark blue pre- 
cipitate, (Prussian blue.) 
sulphuret 
44 
28 I.+ 16 S. 
bisulphuret 
60 
28 I.+32S. 
hyposulphite ? 
protosulphate 
76 
36 O. I.+40 S. A. 
crystallized 
1.83 
139 
76 dry + 63W. (7 props.) 
persulphate ? 
. | 
hydrosulphuret 
40 
28 I. +12 P. 
protophosphate 
64 
36 0.1.+28 P. A. 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
1 
Iron, perphosphate ? 
carburet 
58 
34 
42 
70 
118 
79 
159 
207 
168 
96 
36 0. I.+ 22 C. A. 
34 Z.+8 0. 
34Z.+36 C. 
42 0. Z.+ 76 C. A. 
42 0. Z. + 37 M. A. 
34 Z.+125 I. 
42 0. Z. + 165 I. A. 
42 0. Z.+126 H. A. 
42 0. Z.+54N. A. 
The Solutions of Zinc are not precipi- 
tated by hydriodic acid. Potassa, 
soda, and ammonia, form white pre- 
cipitates redissoluble in excess either 
of acid or alcali. Hydrosulphuret of 
ammonia produces a yellowish white 
precipitate; and the soluble phos- 
phates, borates, and carbonates, all 
form white precipitates. 
X 7inc 
7 
Metals and their Combinations (continued.) TABLE OP EQUIVALENTS. 
429 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
50 
34 Z. +16 S. 
06 
42 0. Z. +24 Hyp. S. A. 
74 
42 0. Z.+ 32 S. A. 
1.9 
82 
42 0. Z. +40 S. A. 
— crystallized 
145 
82 Z.+63 Water (9X7) 
hydrosulphuret 
46 
34 Z. +12 P. 
70 
42 0. Z.+ 28 P. A. 
64 
42 0. Z. +22 C. A. 
64 
42 0. Z. +22 B. A. 
7.30 
59? 
The Hydriodic Acid affords a fine 
orange precipitate with solution of 
1. oxide . 
67 
59 T.+8 0. 
muriates of tin, provided there be no 
Metals and their Combinations (continued.) TABULAR VIEW ©F 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
75 
59 T. + 16 Ch 
excess of acid. Hydrosulphuret of 
ammonia produces a precipitate of a 
95 
59 T. + 36 0. 
deep orange colour. 
131 
59 T. + 72 C. 
protomuriate 
104 
67 0. T.+37 M. A. 
• 
149 
75 0. T. + 74 M. A. 
184 
59 T.+ 1251. 
121 
67 0. T.+ 54N. A. 
sulphuret 
75 
59 T.+ 16. S. 
91 
59 T.-+32S. 
107 
67 0. T. +40 S. A. 
hydrosulphuret 
phosphuret . 
71 
59 T. +12 P. 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, SfC. 
431 
SUBSTANCES 
Specific 
Gravity. 
Equivalent 
Number 
COMPOSITION 
REMARKS 
8.63 
55.8? 
63.8 
91.8 
180.5 
117.8 
71.8 
103.8 
67.8 
91.8 
85.8 
64 
72 
55.8 C.+8. 0. 
55.8 C. + 36. Chlor. 
55.8 +125. Iod. 
63.8 0. C. +54. N. A. 
55.8 C.+16 S. 
63.8 0. C.+40. S. A. 
55.8 C. + 12P. 
63.8 0. C.+28 P. A. 
63.8 0. C. + 22. C. A. 
64C. + 8 0. 
Cadmium is readily soluble in muriatic 
acid. Its neutral solutions are pre- 
cipitated yellow by sulphuretted hy- 
drogen, and furnish a metallic pre- 
cipitate upon immersed zinc. 
The annexed equivalent of Cadmium 
is deduced from Stromeyer’s Analy- 
ses (.1419.) 
The salts of this metal containing the 
peroxide, are distinguished by their 
blue and green colours; their solu- 
XIII. Copper 
8.8 
— 1. oxide 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
Copper. 2. oxide 
80 
100 
136 
189 
117 
154 
188 
80 
96 
104 
64 C. +16. O. 
64 C. +36 C. 
64 C. +72 C. 
64 C. + 125 I. 
80 0. C. + 37M. A. 
80 O. C. + 74 M. A. 
80 0. C.+108 N. A. 
64 C. +16 S. 
64 C. + 32S. 
80 0. C. +24 Hyp. S. A. 
tions afford blue precipitates of hy- 
drated oxide with the alcalis, and 
these redissolve in excess of ammo- 
nia, producing a deep blue solution. 
A plate of iron precipitates metallic 
copper; ferrocyanate of potassa af- 
fords a fine brown precipitate; hy- 
drosulphuret of ammonia, one of a 
dirty brown; hydriodic acid produces 
an insoluble iodide of an ash grey co- 
lour. The salts of copper contain- 
ing the protoxide have hitherto been 
but imperfectly described. 
— chlorate 
2.17 
ammoniuret 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, fyc. 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
Copper, persulphite 
112 
80 O. C.+32 S. A. 
potassa persulphite 
192 
80 O. C.+64 S. A.+ 48 pot. 
• persulphate (dry) 
160 
80 O. C.+80 S. A. 
— ■ persulphate crystallized 
2.19 
250 
80 O. C.+80 S. A.+90 water. 
■ subpersulphate 
- hydrosulphuret 
phosphuret 
76 
64 C.+12 P. 
• protophosphate 
100 
72 0. C. +28 P. A. 
— perphosphate 
136 
80 0. C.+ 56 P. A. 
102 
80 0. C.+22C. A. 
102 
80 0. C.+22 B. A. 
XIV. Lead 
11.35 
104 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
112 
104 L.+ 8 0. 
104 L. +12 0. 
The soluble Salts of Lead furnish co- 
116 
lourless solutions of a sweetish taste, 
precipitated white by sulphate and 
ferrocyanate of potassa, and by infu- 
sion of galls; brownish black by sul- 
phuretted hydrogen ; and brown by 
nydrosulphuret of ammonia. Hy- 
driodic acid affords a fine yellow 
precipitate of iodide of lead. The 
alcalis produce white precipitates, 
easily soluble in excess of potassa oi 
soda, but insoluble in excess of am- 
monia. Zinc precipitates metallic 
lead. The insoluble salts of lead 
treated by the blow-pipe on charcoal, 
afford a globule of lead. 
120 
104 L. +16 0. 
104 L. + 36 C. 
140 
188 
112 0. L.+76 C. A. 
104L. + 125 I. 
112 0. L. + 165 I. A. 
229 
277 
166 
112 0. L.+54 N. A. 
278 
224 0. L. + 54 N. A. 
104 L. +16 S. 
112 0. L.+32 S. A. 
120 
144 
152 
112 0. L.+40S. A. 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, IfC. 
SUBSTANCES. 
1 
Specific 
Gravity 
1 
Equivalent 
Number 
1 
COMPOSITION. 
REMARKS 
Lead, hydrosulphuret 
116 
132 
140 
134 
48? 
56 
64 
84 
173 
64 
104 L. +12 P. 
112 0. L. + 20Ps. A. 
112 0. L. +28 P. A. 
112 O. L.+22 C. A. 
48 A.+ 8 0. 
48 A.+ 16 0. 
48 A.+36 C. 
48 A.+ 125 I. 
48 A.+ 16 S. 
The protomuriate of antimony is preci- 
pitated white by water; the precipi- 
tate is a subsalt. Sulphuretted hy- 
drogen, and hydrosulphuret of am- 
monia, give an orange precipitate, 
and a plate of iron or zinc throws 
down the metal in the form of a black 
powder. 
6.70 
muriate 
Metals and their Combinations (continued.) TABVLAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
96 
60 
84 
72 
80 
100 
197 
134 
88 
120 
56 0. A.+ 40 S. A. 
48 A.+12 P. 
56 0. A.+28 P. A. 
72 B.+8 0. 
72B. + 36 C. 
72 B.+125 I. 
80 0. B. +54 N. A. 
72 B.+ 16 S. 
88 0. B.+40S. A. 
The Salts of Bismuth are precipitated 
white by water—brownish black by 
sulphuretted hydrogen—yellowish 
white by ferrocyanate of potassa, and 
hydriodic acid affords a deep brown 
iodide of bismuth, 
1 
hydrosulphuret 
9.80 
• 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, S^C. 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
8 
32.5 ? 
40.5 
32.5C. + 8 0. 
32.5 C. +12 0. 
32.5 C. + 36C. 
40.5 0. C. +37 M. A. 
32.5 C.+ 16 S. 
40.5 0. C. + 40 S. A. 
(40.5 0. C.+40S. At 
$ 63 Water. 
red colour, when in dilute solution, 
but green or blue when concentrated ; 
potassa, soda, and ammonia produce 
in them blue precipitates of hydrated 
oxide, which is soluble in excess of 
ammonia, producing a red solution. 
Hydrosulphuret of ammonia gives a 
black precipitate: Ferrocyanate of 
potassa a pale green. Carbonates, 
phosphates, and arseniates, produce 
red precipitates. Hydriodic acid does 
not precipitate the salts of cobalt. 
44.5 
68.5 
77.5 
48.5 
80.5 
143.5 
44.5 
32.5 C. + 12P. 
68.5 
40.5 0. C. +28 P. A. 
40.5 0. C.+22C. A. 
62.5 
9 
64? 
Metals and their Combinations (continued.) TABULAR VIEW OV 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
72 
64 U.+8 0. 
64 U. .fl6 0. 
Of the salts of Uranium the greater 
number are soluble, and of a greenish 
yellow colour ; they form yellow pre- 
cipitates with the alcalis, and afiord 
a reddish yellow iodide with hydrio- 
dic acid. Ferrocyanate of potassa 
forms a precipitate of a rich brown 
colour, and h) drosulphuret of ammo- 
nia one nearly black. 
80 
XIX. Titanium 
91.9? 
The Salts of Titanium are colourless, 
and afford white precipitates with the 
alcalis. Ferrocyanate of potassa gives 
a green precipitate, ana infusion of 
galls a red one. Hydrosulphuret of 
ammonia gives a green precipitate. 
107.9 
91.9 C. + 16. 0. 
91.9 C.+24 0. 
115.9 
61.0 
39? 
47 
39 T.+8 0. 
39 T.-f 36 C. 
75 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, <$*C. 
SUBSTANCES 
Specific 
Gravity. 
Equivalent 
Number 
COMPOSITION 
REMARKS 
8.3 
3.7 
47? 
63 
71 
119 
137 
422 
63 
79 
47 A.+ 16 0. 
47 A.+ 24 0. 
47 A. + 72 C. 
63 0. A.+74 M. A. 
47 A.+375 I. 
47 A.+ 16 S. 
47 A.+32 S. 
Hydriodic Acid produces a precipitate 
of white oxide of arsenic, when add- 
ed to arsenite of potassa, and hydrio- 
date of potassa is formed. Arsenite 
of potassa gives a white precipitate 
with hydrosulphuret of ammonia ; a 
white precipitate soon becoming yel- 
low and brown with nitrate of silver ; 
a grey precipitate with protonitrate, 
and a white with pernitrate of mer- 
cury ; a white with nitrate of lead; 
a pale green with nitrate of nickel; 
pale pink by nitrate of cobalt; apple 
green with nitrate of copper; white 
with the protomuriate and permuriate 
of tin ; dingy green with the muriates 
of iron; white with sulphate of zinc; 
bright yellow with nitrate of uranium. 
WTTT A.PRwwTr 
1. oxide (arsenious acid) .... 
hydruret 
arseniuretted hydrogen 
sulphate 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
88 
119 
190 
103 
99 
149 
123 
91 
107 
107 
146.5 
113 
138 
71 A. A.+17 A. 
71 A. A.+ 48 P. 
142 A. A.+48 P. 
71 A. A.+ 32 0. S. 
71 A. A. + 28 Lime. 
71 A. A.+ 78 0. B. 
71 A. A. + 52 S. 
71 A. A. + 20 M. 
71 A. A.+36 O. M. 
71 A. A. + 36 0. I. 
106.5 A. A.+ 400.1. 
71 A. A.+42 0. Z. 
71 A. A.+67 O. T. 
Tlic Arseniate of Potassa produces a 
reddish precipitate in nitrate of sil- 
ver ; straw-coloured with nitrate, and 
yellow with pernitrate of mercury: 
white with nitrate of lead; pale green 
with nitrate of nickel; pale blue with 
nitrate of copper; pink with nitrate 
of cobalt; white with protomuriate 
of tin; no precipitate with permuri- 
ate of tin ; pale sea-green with mu- 
riate and pennuriate of iron ; straw 
colour with nitrate of uranium; and 
white with sulphate of zinc. 
The compounds of the arsenic and #r- 
senious acids are decomposed when 
heated with charcoal, and exhale an 
alliaceous smell. 
magnesia 
Protarseniate of iron 
Arseniate of zinc 
tin 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
143 
71 A. A.+72 0. C. 
220 
142 A. A.+80 0. C. 
• * r 1 J 
183 
71 A. A.+ 112 0. L. 
151 
71 A. A. + 80 0. B. 
111.5 
71 A. A.+40.5 0. C. 
— uranium? 
XXIV. Molybdenum 
7.40 
47? 
55 
47M.+8 0. 
G3 
47 M. + 160. 
— ■ 3. oxide (acid) 
71 
47 M.+240. 
—————— sulphuret 
79 
47 M.+32 S. 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
119 
103 
183 
30.9? 
38.9 
46.9 
63.9 
94.9 
74.9 
124.9 
82.9 
71 M. A. + 17 A. 
71 M. A.+48 P. 
71 M. A. + 32S. 
T1 M. A.+ 112 0. L. 
30.9 C. + 8 0. 
30.9 C.+ 16 0. 
46.9 C. A.+17 A. 
46.9 C. A.+48 P, 
46.9 C. A.+28 L. 
46.9 C. A.+ 78 B. 
46.9 C. A.+36 0. I. 
Chromic Acid and Chromate of Soda 
produce insoluble precipitates in so- 
lutions of silver, mercury, lead, cop- 
per, iron, and uranium ; the colours 
are crimson, red, yellow or orange, 
apple-green, brown, and yellow. No 
precipitate is formed in solutions of 
nickel, zinc, tin, cobalt, gold, or pla- 
tinum. 
5.9 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, fyc. 
443 
SUBSTANCES. 
Specific 
Gravity 
I 
Equivalent 
Number 
i 
COMPOSITION. 
REMARKS 
158.9 
96 
120 
148 
156 
145.8? 
153.8 
201.8 
29.63 ? 
37.63 
46.63 
46.9 C. A. +112 0. L. 
96 T. +24 0. 
120 T. A.+28 L. 
120 T. A.+36 0. M. 
145.8 C. +8 0. 
153.8 C. A.+48 P. 
29.63 N. + 8 0. 
37.63 0. N.+9W. 
The Salts of Nickel form green solutions, 
of a sweetish acrid flavour; ammonia 
gives green precipitates, redissoluble 
in excess of alcali, and forming triple 
salts. Ferrocyanate of potassa forms 
17.5 
XXVIII. Nickel 
8.5 
oxide 
hydrate 
Metals and their Combinations (continued.) TABULAR VIETT ©F 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
1 
Nickei. chloride 
iodide 
nitrate 
ammoniuret 
sulphuret 
sulphate (dry) 
crystallized 
potassa-sulphate 
ferro-sulphate 
——j phosphuret 
phosphate 
carbonate 
65.63 
154.63 
91.63 
45.63 
77.63 
140.63 
165.63 
153.63 
41.63 
65.63 
59.63 
29.63 N.+36 C. 
29.63 N.+125 I. 
37.630. N.+54N. A. 
29.63 N.+16 S. 
37.63 0. N. +40 S. A. 
77.63 S. N. + 63W. 
37.63 0. N.+80 S.A.+48P. 
37.63 0. N.+80 S. A.+36 0.1. 
29.63 N.+ 12 P. 
37.63 0. N.+28 P. A. 
37.63 0. N.+22C. A. 
a greenish precipitate; hydrosulphu- 
ret of ammonia gives a black preci- 
pitate; hydriodic acid forms a pea- 
green iodide. 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, <£’C. 
445 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
134.63 
200 
208 
216 
236 
272 
Mercury is ye 
stals. 
325 
450 
334 
37.63 O. N. + B. A.) 
37.63 O. N. + 80 S. A. +17 amm. 
200 M. + 8 O. 
200 M. +16 O. 
200 M. + 36 C. 
200M.+72C. 
low and insoluble. Perehlofate fur- 
200 M.+125 I. 
200 M.+250 I. 
208 O. M.+126 H. A. 
The Mercurial Salts are volatilized by 
heat. They are precipitated yellow- 
ish by ferrocyanate of potassa; deep 
brown by hydrosulphuret of ammo- 
nia ; and copper separates pure mer- 
cury. The salts with the protoxide, 
give black precipitates with the alca- 
lis, and white with muriatic acid. 
The salts with the peroxide furnish to 
the fixed alcalis reddish precipitates, 
and white with ammonia. 
Hydriodic Acid gives a yellow precipi- 
tate in solutions of protoxide, and a 
red precipitate with the peroxide. 
These are the protiodide and perio- 
dide of mercury. 
YYTY MffnrTT nv 
13.50 
Chlorate of 
nishes cry 
■ chlorate 
Metals and their Combinations (continued.) TABULAR VIEW OP 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
Mercury, protonitrate 
262 
324 
486 
216 
232 
240 
248 
296 
256 
208 0. M. -f N. A. 
216 0. M.-f 108 N. A. 
432 0.M. + 54N. A. 
200 M.-f. 16 S. 
200 M.+32S. 
208 O. M. + 32 S. A. 
208 0. M.-f-40 S. A. 
216 0.M.-f-80S. A. 
216 0. M.-J-40 S. A. 
Phosphoric Acid produces a white inso- 
luble precipitate in nitrate of mercu- 
ry, but no precipitate in the penii- 
trate. 
pemitrate 
subpemitrate 
sulphuret 
• bisulphurct 
* sulphite ? 
protosulphate 
— persulphate 
bipersulphate ? 
* subpersulphato 
hydrosulphuret ? 
phosphuret ? 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, SfC. 
447 
Specific 
Equivalent 
COMPOSITION 
SUBSTANCES 
Gravity. 
REMARKS 
Number 
236 
208 0. M.+28 P. A. 
216 0. M. + 56 P. A. 
208 0. M. + 22 C. A. 
260 
216 0. M. + 44C. A. 
252 
200 M. + 52 C. 
230 
208 0. M.i"22 B. A. 
260 
279 
216 0. M.-f 44 B. A. 
208 0. M. + 71 A. A. 
358 
216 0. M.+142 A. A. 
—■ ■ ■ chromate ? 
— tungstate ? 
XXX. Osmium. 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
18 
• 
106 
11 
XXXIV. Silver 
10.50 
109.3? 
117.3 
145.3 
The salts of silver are reduced upon 
charcoal by the blow-pipe. The so- 
luble salts are precipitated by the al- 
calis, which furnish dark olive preci- 
pitates ; by sulphuretted hydrogen 
109.3 S.-f-8 ox. 
109.3 S.+36 C. 
A detonati 
Hydriodic 
first whit 
blackish. 
and hydrosulphuret of ammonia, 
nearly black; by infusion of galls, 
yellow brown; by ferrocyanate of 
potassa, white. Muriatic acid, and 
the muriates, give white precipitates 
of chloride of silver. Sulphate of 
iron, and a plate of copper, throw 
down metallic silver. 
iodide i 
hydriodate ) 
icid throws down iodide of silver from the nitrate, at 
e, but becoming very soon yellow, then grey and 
171.3 J 117.3 0. S. + 54N.A. 
nonia easily dissolves the oxide of silver. When 
on is evaporated, a grey compound remains, which 
tallic silver when heated. Sometimes it detonates. 
ammoniuret j 
Liquid ami 
the soluti 
leaves mt 
Metals and their Combinations (continued.) EQUIVALENT NUMBEBS, fyc. 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
Silver, sulphuret . . . . 
- sulphite 
sulphate 
hydrosulphuret . . . 
phosphuret. . 
• phosphate 
— carbonate 
■ cyanuret .... 
• — hydrocyanate 
borate | 
Arseniate of Silver 
Molybdate — . . . 
forms a wh 
Boracic 
but boi 
ver. 
125.3 
ite and difficul 
157.3 
121.3 
145.3 
139.3 
161.3 
cid produces 
ate of soda tl 
188.3 
188.3 
109.3 S. +16 Sul. 
ly soluble salt. 
117.3 0. S.+40 S. A. 
109.3 S. +12 P. 
117.3 0. S.+28 P. A. 
117.3 0. S.+22 C. A. 
109.3 0. S.+52 C. 
no precipitate in solutions of silver, 
irows down a white borate of sit- 
in.3 0. S. +71 A. A. 
117.3 0. S. +71 M. A. 
Metals and their Combinations (continued.) TABULAR VIEW OF 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
Silver. Chromate 
164.2 
237.3 
103.4? 
111.4 
139.4 
148.4 
icid produces 
tteofgold, whi 
odine. 
165.4? 
135.4? 
acid produces 
117.3 0. S.+46.9C. A. 
117.3 0. S. + 120T. A. 
103.4 G. + 8ox. 
103.4 G. +36 C. 
111.4 ox. G.i-37. M. A. 
in insoluble yellow precipitate in di- 
ch is the iodide of gold. Heat sepa- 
111.4 ox. G. + 54N. A. 
103.4 G. +32 S. 
a metallic precipitate in solution of 
The salts of 'gold are yellow and solu- 
ble in water. Potassa and soda pro- 
duce in them yellow precipitates. 
Sulphuretted hydrogen and hydrosul- 
phuret of ammonia occasion black- 
precipitates : phosphuretted hydro- 
gen, a purple precipitate: a plate of 
tin or muriate of tin, a purple powder. 
Sulphate of iron separates minutely-di- 
vided metallic gold. Tincture of galls 
gives a brown precipitate. Ferrocy- 
anate of potassa occasions no preci- 
pitate. 
—— Tungstate 
XXXV. Gold 
19.30 
chloride 
muriate 
chlorate 
iodide . t 
hydriodate ( 
nitrate 
Hydriodic 
lute mum 
rates the 
sulphuret 
sulphite 
Sulphurous 
gold. 
Metals and their Combinations (continued.) EQUIVALENT NUMBERS, &C, 
SUBSTANCES. 
Specific 
Gravity 
1 
Equivalent 
Number 
COMPOSITION. 
REMARKS 
Gold, sulphate 
phosphuret 
phosphite ..'••• ) 
■ phosphate 5 
carbonate 
cyanuret 
XXXVI. Platinum 
protoxide 
■ " peroxide 
■■■ chloride 
muriate 
Neither thes 
tate in so: 
115.4 
« acids, nor th 
ution of muria 
103.4 G+12 P. 
air neutral salts, occasion any precipi- 
e of gold. 
The solutions of these salts are deep or 
brownish yellow. They afford no 
precipitate with solutions of soda, ol 
sulphate of iron, or of Ferrocyanate 
of potassa. The addition of the lat- 
ter produces a fine green solution. 
Potassa and ammonia, and many oi 
their salts, occasion yellow precipi- 
tates. Sulphuretted hydrogen occa- 
sions a black precipitate. Infusion 
Metals and their Combinations (continued.) TABULAR VIEW dP 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
PuifiNUM. iodide C 
— hydriodate ( 
nitrate 
armnoniuret 
. 
ammonio-muriate 
sulphuret 
■ sulphate 
—■ ■> hydrosulphuret j 
phosphuret 
phosphate j 
XXXVII. Silicium 
Hydriodic a 
decompos 
Hydrosulph 
riate of p 
phuret. 
A soluble sa 
phoric aci 
cid precipitate 
ed by heat. 
1 ret of ammoni 
atinum. This 
t, obtained by 
d. 
16 
s a dingy brown iodide of platinum, 
a produces a brown precipitate in mu- 
is probably a sulphuretted hydrosul- 
dissolving oxide of platinum in phos- 
of galls gives a dingy brown precipi- 
tate. 
The analysis of these compounds are, at 
present, too much at variance to ena- 
ble us, with sufficient precision to as- 
certain the representative number of 
Platinum. 
Metals and their Combinations (continued.) EQUIVALENT iftfMBERS, fyc. 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
2.6 
32 
16 S. + 16 0. 
Of the following bodies such combina- 
tions only are here set down as have 
3.574 
=sp. er. to 
atmospheric air. 
been examined with sufficient preci- 
sion. Their distinctive characters are 
49.2 
=sp. gr. to 
hydrogen. 
given at length in the text. 
] 
110,78 
grs.=weight 
of 100 C. I. 
yyyvttt 
17.6 
AAA V HA* 
25.6 
17.6 A.+ 8 0. 
sulphate 
65.6 
25.6 0. A.+40S. A, 
259.2 
131.2 S. A.+ 128 Bisul. Pot. 
(crystallized) 
457.2 
259.2 dry +198 Water (22 props.) 
XXXIX. 
37? 
Zirconia 
45 
37 Z. + 8 0. 
Metals and their Combinations (continued.) TABULAR VIEW &C. 
SUBSTANCES 
Specific 
Gravity 
Equivalent 
Number 
COMPOSITION 
REMARKS 
21.3 ? 
Glucina 
2.97 
29.3 
21.3 G. 4.8 0. 
32 
40 
32 Y. + 8 0. 
XLII. Thorinum 
Metals and their Combinations (continued.) STRUCTURE OF VEGETABLES. 
455 
CHAPTER VIII. 
OF VEGETABLE SUBSTANCES. 
1523. Having in the preceding chapters considered the properties 
of the elementary substances, and such of their compounds as can be 
artificially formed, or are found in the mineral world, we proceed in 
this and in the succeeding chapter to examine the states of combination 
in which they occur in organic substances. 
The several sections of the present chapter will relate to the forma- 
tion of vegetable substances and their chemical physiology ; to the 
analysis of vegetable products, and the properties of their proximate 
component parts ; and to the phenomena and products of fermentation. 
Objects of this 
chapter. 
Segtion I. Of the Structure and Growth of Plants, and of the chemical 
Phenomena of Vegetation. 
1524. In examining the external structure of a perfect and full-grown' 
vegetable, or plant, the essential organs of which it is observed to con-1 
sist are the root, the stem, the leaves, the flowers, and the seeds. 
The root serves to attach the plant to the soil, and is one of its or-j 
gans of nutriment; in its structure it closely resembles the stem, of 
which it may be regarded as a continuation, terminating in more or less 
minute ramifications, analogous to the branches deprived of leaves. 
The stem is usually erect and subdivided into branches which bear thej 
leaves and flowers, and upon which the seeds are ultimately produced, l 
1525. When a branch of a tree is cut transversely it exhibits a cor- ( 
tical portion, or bark; wood; and pith, or central medullary substance, i 
The bark is subdivisible into an external layer or cuticle, under which ( 
is a cellular substance lying upon the innermost part, or cortical layers. s 
1526. The cuticle extends over every part of the plant; it allows 
©f absorption and transpiration, and being generally transparent, at least 
upon the leaves and flowers, it admits the influence of light. The( 
cuticle varies in texture and appearance in different plants. On the 
currant and elder tree it is smooth and scales off: on the fruit of the 
peach, and on the leaf of the mullein, it is covered with wool ; on the 
leaf of the white willow, it is silky ; in several plants, it is covered with 
hair and bristles, which in the nettle are perforated and contain a ve- 
nomous fluid : on the plum and upon many leaves, it is varnished with 
a resinous exudation, which prevents injury from rain : it is fungous on 
the bark of the cork tree : and on grasses, on the equisetum, and es- 
pecially on different species of the rattan, it is covered with a glassy 
network of siliceous earth. 
Silica is also found in the hollow stem of the bamboo, constituting the 
substance called tabasheer, the optical properties of which are peculiar, 
and have been described by Dr. Brewster.—Phil. Trans. 1819. 
1527. Under the cuticle, or epidermis, is the parenchyma ; a softi 
Organs 
plants. 
Root. 
Stem. 
Leaves, 
Cortex wood, 
medulla. 
Cellular sub- 
stance. 
Cuticle. 
Parenchyma- 456 
PITH, LEAVES, AND FLOWERS. 
substance, appearing under the microscope of a honeycombed or hexa- 
gonal cellular structure, resulting from the mechanical laws which in- 
fluence the pressure of soft cylinders. 
1528. The cortical layers appear of a tubular and fibrous texture, 
and with the cellular substance receive and elaborate the sap. In the 
older branches and trunks of trees, the bark consists of as many lay- 
ers as they are years old ; the innermost layer has been called the li- 
ber, in which the most essential vital functions of the plant appear to go 
on, and by which a new layer of wood is annually secreted. 
1529. The wood consists of an outer stratum of living wood called 
the alburnum, or sap-wood; and an inner dead part, or heart-wood. In 
the alburnum, whicli is tubular, the sap appears to rise from the roots ; 
it passes into the leaves, where it undergoes changes, and thence en- 
ters the vessels of the inner bark, in which new parts are produced, 
and which is thus enabled to generate new wood. 
When the tubular structure is examined by a magnifier, it appears 
composed of vessels, some of which are simple, others perforated in 
various ways, and others spiral. The fibres of the wood consist of 
concentric and diverging layers, which have been called the spurious 
and the silver grain. 
1530. The pith occupies the centre of the wood ; it is very variable 
in quantity in plants of different ages, and appears not to be of essen- 
tial importance. It probably sometimes serves as a reservoir of mois- 
ture. 
1531. The leaves are highly vascular, and appear composed of a 
woody skeleton, supporting a tubular and cellular structure. They 
allow of evaporation and absorption, and in them the sap is concocted 
and rendered fit for the production of new parts. The absorption and 
evaporation principally take place upon the lower surface of the leaf. 
In most plants the leaves are annually re-produced. 
1532. The jlower consists of the calyx, or green support of theco- 
,rolla, or floral leaves; and of the pistil and stamens. The pistil is 
’surmounted by the style, and is connected with a vessel containing the 
rudiments of the seeds. The stamens are surmounted by anthers, co- 
vered with a fine powder called the pollen, and which, being deposit- 
ed upon the style, renders the seeds productive. 
1533. The seed is extremely various in form. It consists essential- 
ly of the cotyledon, the plume, and the radicle. The cotyledon con- 
tains the matter necessary for the early nutrition of the young plant. 
Sometimes it is single sometimes double, and sometimes divisable into 
geveral lobes. The plume afterwards 
produces the stem and leaves, and is 
enveloped by the cotyledons ; the ra- 
dicle generally projects a little, and 
when the seed vegetates it becomes the 
root. These parts are usually envelop- 
ed in a common membrane, and are well 
seen in the garden bean, represented 
in the annexed cut. an are the cotyle- 
dons ; b the plumula ; c the radicle"; d 
d the external membrane. 
1534. When a seed is placed under favourable circumstances the 
different parts begin to grow; the membranes burst, the plumula gra- 
Cortical lay- 
ers. 
Sap-wood- 
Heart-wood. 
Spurious and 
silver grain. 
Pith. 
Leaves. 
Flower of ca- 
lyx, corolla, 
pistil, stamen, 
style, anthers, 
pollen. 
Seed, cotyle- 
don, plume, ra- 
dicle. FUNCTIONS OF THE LEAVES. 
dually expands and rises to the surface of the soil, and the radicle puts 
forth ramifications, and becomes a root. 
These changes constitute germination. The 
cotyledons, originally insipid and farinaceous, 
become sweet and mucilaginous, and furnish 
materials for the early nutriment of the young 
plant, before its root and leaves are adequate 
to their full functions ; and vessels are ob- 
served ramifying throughout the cotyledons 
for this purpose, as here represented. 
When the root and stem have acquired a 
certain degree of vigour, the cotyledons ei- 
ther rot away, or become leaves : and the plant then derives it nour- 
ishment by the absorbing powers of the root and leaves, the former 
collecting materials from the soil, the latter from the atmosphere. 
The circumstances requisite for the healthy germination or growth 
of a seed are principally the following: 1. A due temperature, which 
is always above the freezing point, and below 100°. 2. Moisture in 
lue proportion. 3. A proper access of air, the oxygen of which is 
slowly converted into carbonic acid. The joint operation of these 
agents also is required ; for seeds exposed to air and moisture, but 
iept below 32°, will not grow, though they are not injured by the low 
:emperature : nor will a seed vegetate without air, though moisture be 
present and a sufficient temperature ; this is shown by burying seeds 
ieep in the soil, and by the spontaneous vegetation upon newly-turned 
sarth, in which seeds had existed, but through absence of oxygen had 
been unable to vegetate. Hence in all cases of tillage the seeds should 
be so sown as that the air may have access ; in sandy soils this is easi- 
ly attained, but in clayey soils the adhesiveness of the materials is of- 
ten the cause of their unproductiveness. 
1535. As the plant advances to perfection, it becomes dependant up- 
on the air and soil for its nutriment: the roots absorb moisture and 
other materials ; and the leaves, while they exhale moisture, frequent- 
ly absorb carbon from the carbonic acid present in the atmosphere, 
and evolve oxygen. This evolution of oxygen takes place while plants 
are exposed to the solar rays, and appears one of the most efficient 
causes hitherto suggested of the purification and renovation of the air. 
In the night-time, the leaves of plants always exhale carbonic acid, 
and at all times if the leaves be dying or unhealthy. There are also 
certain plants which appear under all circumstances rather to deterio- 
rate than renovate the air ; on the whole, however, the balance is in 
favour of amelioration (Davy’s Agricultural Chem. 4to. p. 195.) though 
the disappearance of the enormous quantities of carbonic acid gas con- 
tinually pouring into our atmosphere, can, I think, scarcely be refer- 
red to the purifying action of vegetables alone. 
Under certain circumstances, the leaves of plants also absorb a con- 
siderable portion of aqueous vapour and water, as is shown by the re- 
suscitation of a drooping plant, on sprinkling it with water, or exposing 
it to a humid atmosphere. It is probable that, in healthy vegetation, 
the absorption of water by the leaves takes place in the night season 
chiefly, and that their principal function in the day is that of transpira 
tion, Upon these subjects the reader may consult Saussure’s Reqher- 
ches Chimiaues sur la Vegetation. 
termination. 
Nourishment. 
Requisites for 
vegetation. 
Air and sfiii- 
Moisture. 458 
MANURES. 
Sap. 
1536. The fluid foundin the vessels of plants is called their sap ; it 
has a motion in the vessels, and appears to rise from the roots in a series 
of tubes in the alburnum ; it then circulates in the leaves, becomes 
changed considerably in composition, and enters the vessels of the in- 
ner bark, enabling it to produce a new layer of wood, and to form the 
peculiar secretions which belong to it, and which, in smaller quantity, 
are also found in other parts of the vegetable. 
The cause of the motion of the sap has never been satisfactorily ac- 
counted for, though it is, perhaps, principally referable to the contrac- 
tion and expansion produced by changes of temperature. 
That the sap ascends in the alburnum, and descends in the liber, or 
inner bark, is shown by making an incision into the former and latter. 
The wound of the one will exude upon its lower surface, and of the 
other upon its upper surface : and if a circular strip of bark be remov- 
ed from a small branch of a tree near the stem, there will, of course, 
be an accumulation of sap in that branch, and its produce of leaves, 
flowers, and fruit, is often remarkably increased by such an operation. 
If the alburnum, on the contrary, of a branch be completely divided, 
it dies, as nourishment is then excluded ; a fact pointed out by Mr. 
Knight; who has also shown, in proof of the situation of the vessels 
carrying the ascending sap, that coloured fluids applied to the root al- 
ways pass upwards in the alburnum only.—Phil. Trans. 1801. 
1537. The sap of plants is of very various composition, and contains, 
besides certain proximate vegetable principles, several saline substan- 
ces, especially the acetates of potassa, and of lime : it also often exhi- 
bits traces of uncombined vegetable acids. The sap of the elm, beech, 
hornbeam, and birch, have been examined by Vauquelin, (Annales de 
Chimie, xxxi.) Dr. Prout has given some account of the sap of the 
vine ; and Professor Scherer has analyzed the sap of the common ma- 
ple. (Thomson’s System, iv. 212.) It is, however, almost impossible 
to collect the ascending sap without admixture of some other juices of 
the plant, so that the analyses only afford approximations to its real 
composition. 
1538. The heat of plants is in many instances above that of the 
surrounding medium, and there are cases on record in which a very 
marked elevation of temperature has been observed in them, but upon 
this subject we have as yet no accurate researches.—Smith’s Introduc- 
tion to Botany, p. 89. 
1539. Though the presence of light, air, and moisture, aided by a 
due temperature, are the principal requisites for the growth of plants, 
these are not the only essentials, for they also derive nutriment from 
the soil, which becomes impoverished by their growth, and ultimately 
incapable of supporting healthy vegetation, unless aided by manures. 
It is thus that the alcaline, earthy, and saline ingredients of plants are 
furnished, and quick-growing vegetables require a constant supply of 
these substances. 
1540. Manures are of vegetable, animal, or mineral origin. The 
two former are capable of affording two of the essential ingredients of 
plants, namely, carbon and hydrogen ; they may also yield some of 
the more immediate principles found in vegetables. The mere exist- 
ence, however, of vegetable matter in the soil, is not sufficient to con- 
stitute it a manure ; it must be reduced to a soluble state ; to a state in 
which it can be absorbed by the roots of a growing vegetable ; this is 
.Asccnt- 
Deseent. 
Composition 
of the Sap. 
Heatef plants. 
Mai mires. DECOMPOSITION OF VEGETABLES. 
often effected by fermentation or putrefaction, or by applying the ve- 
getable matter in a green state, as by ploughing in a green crop. 
Where the vegetable matter is in an inert insoluble form, it will be of 
no avail unless rendered active and soluble, which is effected either by 
mixing it with such kinds of animal matter as undergo quick putrefac- 
tion, and are themselves propitious to the growth of vegetables ; such, 
for instance, as dung, rotten fish, or decaying parts of animals ; or, by 
die operation of alcaline bodies, such as quicklime, 4’C. 
When newly burned lime is strewed over a soil containing inert ve- 
getable matter, it acts upon it, and renders it more or less soluble ; 
while the lime, by absorbing moisture and carbonic acid, is slaked, and 
passes into the state of chalk, which is not hurtful to vegetables, and 
often a very useful addition to the soil : but when limestone contains 
magnesia, that earth remains caustic, and sometimes proves highly in- 
jurious.—Davy’s Agricultural Chemistry, 4to. p. 234. 
Section II. Of the Composition and Analysis of Vegetable Substances, 
and of their ultimate and proximate Principles. 
1541. The ultimate principles of vegetable substances are few in 
number ; but by being combined in various proportions, they give 
rise to a series of compounds materially differing from each other, and 
which may be called their proximate component parts. 
Carbon, hydrogen, and oxygen, are the principal ultimate compo- 
nents of vegetables : some afford nitrogen ; in some there are traces 
of sulphur ; and in their sap or juices we find small proportions of po- 
tassa and of lime, sometimes of soda and of magnesia ; these bodies are 
combined with acids, and chiefly obtained by burning or incineration. 
It has already been said, that some plants contain silica; sulphate of 
lime is found in clover, nitrate of potassa in the sap of the sun-flower, 
and nitrate of soda in barley. Common salt is a very frequent ingre- 
dient in marine plants ; phosphate of lime is found in oats and some 
other seeds ; and nearly all vegetables yield traces of oxide of iron, 
and many of oxide of manganese. In Saussure’s Chemical Researches 
on Vegetation, and in the fourth volume of Dr. Thomson’s System of 
Chemistry, are copious tables, showing the earthy and saline consti- 
tuents of vegetables. 
1542. When vegetable substances are submitted to destructive dis- 
tillation, the carbon, hydrogen, and oxygen which they contain enter 
into new arrangements, and a variety of products are obtained, differ- 
ing in quantity and quality according to the nature of the vegetable sub- 
stance, and varying with the mode of distillation. Water, empyreu- 
matic oil, acids, carbonic oxide and acid, and carburetted hydrogen, are 
in this way formed ; and if the vegetable contain nitrogen, ammonia 
may be obtained. A portion of charcoal, with the saline and earthy 
ingredients, remains in the retort. By a careful analysis of these pro- 
ducts, the relative proportions of carbon, hydrogen, and oxygen, and of 
nitrogen, if present, may be judged of. The following form of appa- 
ratus may be used in these researches : 
Ultimate prin- 
ciples. 460 
ANALYSIS OF VEGETABLES. 
« is a glass or earthen retort, containing the vegetable substance to be 
decomposed, and placed in a sand heat upon the furnace b, which is 
gradually raised to a red heat. It is connected by the adapter c with the 
receiver d, which is kept cool for the condensation of the liquid pro- 
ducts ; the gases pass into the bell-glass/ standing over mercury, e i$ 
a tube of safety, to allow for sudden expansion or contraction ; there 
being in its lower part a small quantity of mercury which is occasional- 
ly elevated or depressed. The joints are secured by lute. 
1543. An improved mode of ascertaining the relative proportions of 
the ultimate component parts of vegetable products has been devised 
by MM. Gay Lussac and Thenard, (Recherches Physico-Chimiques, 
Tom. ii.) It consists in burning the vegetable substance with chlorate 
of potassa (546.) The requisite proportion of the chlorate, ascertain- 
ed by previous experiment, is mixed with a given weight of the vege- 
table matter, and made into a small ball, which is dried, and burned in 
the apparatus described in the opposite page. The gases are collected 
over mercury. The carbonic acid is absorbed by solution of potassa ; 
if nitrogen be present, it will be found in the residuary gas ; if carbu- 
retted hydrogen has been disengaged, its quantity and composition may 
be ascertained by detonation with oxygen. There should, however, 
always be allowance made for the production of excess of oxygen : 
thus the quantity of carbon is estimated from that of the carbonic acid 
formed ; the quantity of hydrogen is deduced from that of the oxygen 
which has disappeared for the production of water ; and the quantity of 
oxygen is learned by the remaining excess. 
The details of the process will be found in the fourth volume of M. 
Thenard’s Traite de Chimie, with the following arrangement and des- 
cription of the apparatus. 
Analysis' \vith 
.chlorate of po- 
tassa; ANALYSIS OF VEGETABLES. 
A hole is made through a brick, l, and the glass tube aa is passed 
through it as far as to the small lateral tube bb, which passes into the 
mercurial trough. The lower extremity of the tube rests upon the 
grate g, where it is to be heated red-hot by charcoal, inflamed by the 
lamp h. A brass cock is fitted by grinding, to the tube ce. It has a so- 
lid plug, dd, in which is a cavity large enough to contain one of the balls 
to be analyzed, and which is introduced at the opening e. The plug is 
then turned round, and the ball falls into the red-hot part of the tube, 
where it burns, the gases passing into the mercurial apparatus, ff is a 
basin, into which ice may be introduced to keep the metallic parts of the 
apparatus cool. It is convenient to case the lower part of the tube a in 
iron, as it is sometimes blown out at that part by the expansion within. 
Further directions respecting this process, with some observations 
upon it by Mr. Daniell, will be found in Mr. Children’s translation of 
M. Thenard’s volume on Analysis. 
1544. A simpler, and in some respects, preferable means of ana- 
lyzing vegetable substances, consists in exposing them to heat with cer- 
tain metallic oxides in vessels which admit of our collecting the resi- 
due and products of combustion. For this purpose, procure a copper 
tube, bored from a solid bar, about twelve inches long, and one-third 
of an inch internal diameter, with a bent brass tube ground to its open 
end, to which is attached, also by grinding, a glass tube containing pow- 
dered muriate of lime, and bent so as conveniently to pass under the 
shelf of the mercurio-pneumatic apparatus ; the muriate of lime may 
be kept it its place by some loose amianthus, and the weight of the 
glass tube should be carefully ascertained. Fill the brass tube loosely 
with dry amianthus ; weigh out 3 grains of the vegetable substance to 
be analyzed, and mix these intimately with 120 grains of finely-pow- 
dered peroxide of copper ; put this mixture into the bottom of the 
copper tube, and afterwards fill it up loosely with oxide of copper ; 
then attach the brass and glass tubes, and arrange the apparatus so that 
the open end of the latter may be brought under an inverted jar of mer- 
cury, and the copper tube placed in a small furnace and surrounded 
with burning charcoal, taking care to apply the heat in the first instance 
to the upper part of it, and afterwards, to the bottom containing the 
vegetable matter ; care should be taken to make the whole of the cop- 
per tube gradually dull red, and to keep the brass tube as cool as pos- 
sible by a damp cloth. During this operation the carbon of the vege- 
table matter will be converted into carbonic acid, and collected over 
the mercury ; the nitrogen, if any, will be mixed with it, and the hy- 
drogen will be converted into water, and absorbed by the muriate ot 
lime. The carbonic acid may be absorbed by liquid potassa, and its 
bulk furnishes a datum upon which to calculate the proportion of car- 
bon, while the increase of weight in the muriate of lime shows the 
quantity of water formed, and consequently the quantity of hydrogen 
in the matter subjected to analysis. If we find the aggregate weight of 
the carbon and hydrogen, or of the carbon, hydrogen, and nitrogen, 
equal to that of the original vegetable substance, no oxygen was pre- 
sent ; but if there be a deficiency it may be referred to oxygen. 
1545. In all analyses thus conducted, the vegetable substance should 
either be previously perfectly dried, or the quantity of adhering wa- 
ter, if there be any, allowed for in summing up the results ; with every 
precaution, however, the method is open to objections, and liable to 
several sources of fallacy. Indeed, although I have frequently made 
With mctall.t 
oxides. ANALYSIS OF VEGETABLES. 
such experiments with every possible caution, I have in no one instance 
gained satisfactory results; the quantity of carbon may, it is true, be 
obtained with sufficient accuracy; but the greatest difficulty attends 
the collection of the water which is formed, and all estimates that I 
have been able to make of the relative proportions of oxygen and hy- 
drogen have been so exceedingly at variance in different trials, as en- 
tirely to shake my confidence in the accuracy of the mode of analysis ; 
and the same difficulty occurs in respect to the nitrogen. When, 
therefore, I see the results of the analysis of a single grain of vegeta- 
ble matter detailed to the third decimal number, I cannot but suspect 
that theory has more share in the result than experiment, more espe- 
cially when such analysis is made the basis of an atomical calculation. 
1546. By subjecting different vegetable substances to ultimate ana- 
lysis, MM. Gay-Lussac and Thenard consider themselves warranted in 
drawing the following conclusions : 
a. A vegetable substance is always acid, when the oxygen which it 
contains is to the hydrogen, in a proportion greater than is necessary 
to form water, or where there is excess of oxygen. 
b. A vegetable substance is resinous, oily, or alcoholic, where the 
oxygen is to the hydrogen in a less proportion than in water, or where 
there is excess of hydrogen. 
c. A vegetable substance is neither acid nor resinous, but saccha- 
rine, mucilaginous, &rc., where the oxygen and hydrogen are in the same 
relative proportion as in water, or where there is no excess of either. 
To the correctness of these results, there are some exceptions which 
have been pointed out by M. Saussure (Thomson’s Annals, Vol. vi.,) 
and by Mr. Daniell (.Journal of Science and Arts, Vol. vi. p. 326,) and 
which tend considerably to shake our confidence in their entire accuracy. 
The following Table exhibits the results of the analysis of several 
Acid. 
Hesinous. 
Saccharine. 
SUBSTANCES 
Carbon 
contained 
in that 
body. 
Oxygen 
contained 
in that 
body. 
Hydrogen 
contained 
in that 
body. 
Or supposing the oxygen and 
hydrogen to be in the state of wa- 
ter in the vegetable substance. 
ANALYZED. 
Carbon. 
W ater. 
Excess of 
Oxygen. 
Sugar 
42.47 
50.63 
6.90 
42.47 
57.53 
0 
Gum arabic 
42.23 
50.84 
6.93 
42.23 
57.77 
0 
Starch . . . 
43.55 
49.68 
6.77 
43.55 
56.45 
0 
Sugar of milk . 
38.825 
53.834 
7.341 
38.825 
61.175 
0 
Oak ... . 
52.53 
41.78 
5.69 
52.53 
47.47 
0 
Beech . . . 
51.45 
42.73 
5.82 
51.45 
48.55 
0 
Mucous acid 
33.69 
62.67 
3.62 
36.69 
30.16 
36.15 
Oxalic acid . 
26.57 
70.69 
2.74 
33.57 
22.87 
50.56 
Tartaric acid . 
24.05 
69.32 
6.63 
24.05 
55.24 
20.71 
Citric acid . 
33.81 
59.86 
6.33 
33.81 
52.75 
13.44 
Acetic acid . . 
50.22 
44.15 
5.63 
50.22 
46.91 
2.87 
hydrogen 
in excess 
Resin oi turpent. 
75.94 
13.34 
10.72 
75.94 
15.16 
8.90 
Copal . . . 
76.81 
10.61 
12.58 
76.81 
12.05 
11.14 
Wax .... 
81.79 
5.54 
12.67 
81.79 
6.30 
11.91 
Olive oil . . 
77.21 
9.43 
13.36 
77.21 
10.71 
12.08 ANALYSIS OF VEGETABLES. 
substances, by the mode above described. Thenard's Treatise on 
Chemical Analysis, translated by A. Merrick. 
1547. The proximate principles of vegetables are chiefly separable i 
from each other by the action of certain solvents, of which the pnnei-1 
pal are cold and hot water, alcohol, ether, and a few of the acids. 
The manner of applying these will be made more obvious by the de- 
tails in the following sections, than by any general account which could 
here be given of the various steps of the analysis. The number of 
proximate principles which are thus capable of being distinguished and 
separated from each other, is considerable ; those which have been 
most accurately examined are enumerated in the following Table, and 
wiil each form the subject of a separate section; while those which 
are less perfectly known, will be adverted to under the titles of those 
which they most nearly resemble. 
Proximate 
principles. 
1 Gum. 
2 Sugar. 
3 Starch. 
4 Gluten. 
5 Extractive matter and Lignin. 
6 Tannin. 
7 Colouring matter. 
8 Wax. 
9 Fixed oil. 
10 Volatile oil. 
11 Camphor. 
12 Resins. 
13 Narcotic principles. 
14 Bituminous substances. 
15 Vegetable acids. 
a. Tartaric acid. 
b. Oxalic acid. 
c. Benzoic acid. 
d. Citric acid. 
e. Malic acid. 
/. Gallic acid. 
Section III. Gum. 
1548. Gum is contained in considerable quantities in the sap of many 
vegetables, and frequently appears as a spontaneous exudation. Gum 
arabic may be taken as a specimen of pure gum. Its specific gravity 
is about 1.4. It has a slightly yellow tint, and is translucent, inodo- 
rous, and insipid. It dissolves in water, forming a viscid solution, or 
mucilage, from which it may be obtained in its original state by eva- 
poration ; it is insoluble in alcohol, which, therefore causes a white 
precipitate in its aqueous solutions ; it is also insoluble in ether and 
oils ; it undergoes no change by exposure to air, and its aqueous solu- 
tion does not ferment, but only becomes slightly sour when kept for 
a long time. 
1549. Gum is decomposed by sulphuric and nitric acids: the for- 
mer produces water, acetous acid, and charcoal; the latter, among 
other products, converts a portion of the gum into a white acid sub- 
stance, called the mucous acid, and which is analogous to that obtained 
from sugar of milk, or saccholactic acid, under which head its prepa- 
ration is mentioned : malic and oxalic acids are also formed. 
Dilute sulphuric, and muriatic acids, dissolve gum without change. 
1550. The alcalies, and solutions of the alcaline earths, also dis- 
solve gum, and the addition of acids occasions its partial precipitation 
without having undergone much apparent alteration. It combines with 
a few of the other metallic oxides. A strong solution of permuriate 
Properties. 
Mucous acle\ 
Solvents »•' 
gum. of iron, dropped into a concentrated mucilage, forms a brown jelly of 
difficult solubility. Silicated potassa also occasions a white flaky pre- 
cipitate in dilute mucilage, and is, according to Dr. Thomson, a very 
delicate test of gum. By mixing caustic ammonia with a boiling solu- 
tion of gum, and then adding subnitrate of lead, Berzelius obtained a 
white precipitate (gummate of lead) composed of 
Gum 
, . 61.75 
Oxide of lead . 
. 38.25 
100. 
If this compound be regarded as consisting of 1 proportional of gum. 
and l of oxide of lead, the number 181 might be assumed as the re- 
presentative of gum, for 38.25 : 61.75 : : 112 : 180.8. But if we con- 
sider it as a compound of 2 of gum and 1 of oxide, then 90.5 would be 
the equivalent of gum, and the following numbers nearly agree with 
its composition, as deduced from experiment: 
6 Proportionals of oxygen 8 
X 
6 == 48.0 — 53.3 
X 
6 = 6.0 = 6.6 
X 
6 = 36. 
= 40 
90 
99.9 
1551. Submitted to destructive distillation, gum affords carbonic acid 
and carburetted hydrogen gases, empyreumatic oil, water, and a con- 
siderable quantity of impure acetic acid, once considered as a peculiar 
acid, and distinguished by the term pyrotnucous acid. 
1552. There are several varieties of gum differing a little from each 
other. Cherry-tree gum and gum tragacanth do not dissolve in cold 
water, but in other respects their properties resemble those of gum 
arabic. To these varieties the generic term of Cerasin has been given 
by some chemists. 
•0>tfcer gums. 
Section IV. Sugar. 
1553. Sugar may be extracted from the juice of a number of vege- 
tables, and is contained in all those having a sweet taste ; that which is 
commonly employed is the produce of the arundo saccharifera, or su- 
gar-cane, a plant which thrives in hot climates. Its juice is expressed 
and evaporated with the addition of a small quantity of lime, until it 
acquires a thick consistency ; it is then transferred into wooden cool- 
ers, where a portion concretes into a crystalline mass, which is drained 
and exported to this country under the name of muscovado, or raw su- 
gar. The remaining liquid portion is molasses, or treacle. 
1554. The following is a sketch of the process by which raw sugar 
is purified in this country. 
Raw sugar is chosen by the refiner by the sharpness and brightnesi 
of the grain, and those kinds are preferred which have a peculiar grey 
Preparation. 
Purification. REFINERY OF SUGAR. 
line. Soft-grained yellow sugars, although they may he originally 
whiter, are not so fit for the purposes of the manufactory, and it is for 
this reason that sugars from particular countries are never used : such 
are those from the East Indies, Barbadoes, 4*c. They do not possess 
the property of crystallizing so perfectly, and approach in this respect 
to the nature of grape sugar. 
There appear to be two perfectly distinct kinds of saccharine mat- 
ter ; one, when pure, is transparent and colourless, and crystallizes 
under proper management in a regular form, generally in flattened six- 
sided prisms ; the other is uncrystallizable, and generally highly charg- 
ed with colouring matter. This colouring matter is not, perhaps, es- 
sential to it, but may arise in the present case from the effect of fire, 
by the agency of which it is peculiarly prone to decomposition. We 
may mention, as familiar instances of these two, white-sugar-candy and 
treacle. The juice of the cane is composed of these ingredients, and 
though they are in some degree separated in our Indian colonies by 
the process of evaporation and filtration, yet the raw sugar which we 
receive contains still much of the latter combined with the former! 
The process of refining consists in further separating the two. 
The proper sugar being selected, the pans, which resemble in some 
measure those used in the West Indies, are charged with a certain por- 
tion of lime-water, with which bullocks’ blood is well mixed by agita- 
tion, They are then filled with the sugar, which is suffered to stand 
a night to dissolve. The use of the lime-water is not, as is generally 
supposed, to neutralize any free acid in the raw material : but, by 
combining with the molasses, to render it more soluble, and thus to fa- 
cilitate its separation from the pure solid sugar. In the purer kinds, 
and more especially when the refined is again melted over for the pur- 
pose of bringing it to its utmost degree of purity, lime is not used, the 
quantity of molasses being so small as to be easily removed by the 
agency of water alone. 
Fires are lighted under the pans early in the morning, and when the 
liquid begins to boil, the albumen of the blood coagulates and rises to 
the top, bringing all the impurities of the sugar with it. These are 
taken off with a skimmer. ’ The liquid is kept gently simmering and 
continually skimmed, till a small quantity, taken in a metallic spoon, 
appears perfectly transparent: this generally takes from four to five 
hours. The whiteness of the sugar is not at all improved by this pro- 
cess, but is even sometimes deteriorated from the action of the fire : it 
only serves to remove all foreign impurities. When the solution is 
judged to be sufficiently clear, it is suffered to run off into a large cis- 
tern. The pans ar§ then reduced to half their size by taking off their 
fronts, and a small quantity is returned into each. The fires are now 
increased,and the sugar made to boil as rapidly as possible, till a small 
quantity taken on the thumb is capable of being drawn into threads by 
the fore-finger. Nothing but practice can ascertain the exact point at 
which the boiling should be stopped : if it is carried too far, the molasses 
is again bound up with the sugar ; and if it is not carried far enough, 
much of the sugar runs off with the molasses in the after-process. 
When this point is ascertained, the fire is instantly damped, and the boil- 
ing sugar carried off in basins to the coolers; a fresh quantity is then 
pumped into the pans, which is evaporated in the like manner. 
When the sugar is in the coolers, it is violently agitated with wood- 
Two kinds of 
saccharine 
matter. 
Lime water. 
Bullock’s 
blood. 
Concentration, 
Graflul^titffi. LOAF-SUGAR. 
eft oars till it appears thick and granulated, and a portion taken on the 
finger is no longer capable of being drawn into threads. It is upon 
this agitation in the cooler that the whiteness and fineness of grain in 
the refined sugar depends. The crystals are thus broken whilst form- 
ing, and by this means the whole is converted into a granular mass, 
which permits the coloured liquid saccharine matter to run off, 
and which would be combined with the solid if suffered to form in lar- 
ger crystals. This granular texture, likewise facilitates the percola- 
tion of water through the loaves in the after-process, which washes 
the minutely-divided crystals from all remaining tinge of the molasses. 
That this is the true theory of the whitening of sugar by the process of 
refining, appears from a comparison with the process for making can- 
dy. In this latter, the raw material is cleared and boiled exactly in 
the same manner; but instead of being put into coolers and agitated, 
it is poured into pots, across which threads are strung, to which the 
crystals attach themselves : these are set in a stove, and great care is 
Jaken not to disturb the liquid, as upon this depends the largeness and 
beauty of the candy. In this state it is left for fife or six days, expos- 
ed to a heat of about 95°, when it is taken out and washed with lime- 
water : this takes off the molasses from the outside, but a great quan- 
tity is combined in the crystals, and the consequence is, that candy is 
never whiter than the sugar from which it is made. 
When the sugar has arrived at that granular state in the coolers 
above described, it is poured into conical earthen moulds, Which have 
previously been soaked a night in water. In these it is again agitated 
with sticks, for the purpose of extricating the air-bubbles which would 
otherwise adhere to the sugar and the moulds, and leave the coat of 
the loaf rough and uneven. When sufficiently cold, the loaves are 
raised up to some of the upper floors of the manufactory, and the pa- 
per stops being removed from their points, they are set, with their 
broad ends upward, upon earthen pots. The first portions of the li- 
quid molasses soon run down, and leave the sugar much whitened by 
the separation. This self-clearance is much assisted by a high tem- 
perature ; and when it is perfected, pipp-clay, carefully mixed up 
with water to the consistence of thick cream, is put upon the loaves to 
the thickness of about an inch : the water from this slowly percolates 
the loaves : and, washing the solid sugar from all remains and tinge of 
the molasses, runs into the pots. The clay is of no other use than to 
retain the water, and prevent its running too rapidly through the mass, 
by which too much of the sugar would be dissolved : a sponge, dipped 
in water, acts in the same manner. The process of claying is repeat- 
ed four or five times, according to the nature of the sugar, and the de- 
gree to which it has been boiled. When the loaves are perfectly 
cleansed from all remains of the coloured fluid, they are suffered to 
remain some time for the water to drain off; when this is completed, 
♦hey are set, with their faces down, when all remains of it return from 
their points, and it is equally diffused throughout: they are then set in 
a stove, heated to about 95°, and thoroughly dried. 
The syrup, or the mixed solution of sugar and molasses which runs 
into the pots, is mingled in the next boilings with the solution of raw 
sugar in the pans, and again evaporated. It is divided according to its 
fineness ; the first running containing, of course, more molasses, is re- 
served for the coarser loaves; whilst the last, being little else than a 
Candying- 
Claying. 
Bastard. ■PURE SUGAR, 
solution of sugar, is boiled into loaves, of the same degree of fineness 
as those from which it ran. The lowest syrups are boiled into what is 
called bastard sugar, from which the molasses runs with very little mix- 
ture of the solid sugar. This is called treacle, and is totally incapable 
of further crystallization. 
The produce of 1 cwt. of raw sugar worked in this manner is, upon 
an average, 
TreaClft. 
63 lbs refined 
18 — bastard 
27 — molasses 
4 — lost weight, dirt, 
112 
The process above described may almost be considered as mechani- 
cal. The only truly chemical parts of it are the clearing with blood, 
and the use of lime-water, which, leaving the solid sugar untouched, 
combines with the molasses, and rendering it in some measure sapona- 
ceous, facilitates its solution during the percolation of the water. ' 
Attempts have lately been made to whiten the sugar during its boil- 
ing, by the addition of charcoal. This destroys some of the colouring 
matter of the molasses, and tends materially to whiten the sugar, es- 
pecially if the charcoal employed be partly of animal origin. 
Another attempt has been made to improve the process of claying, 
by the substitution of a strong solution of very white sugar for the 
clay. The idea was, that the water having a stronger affinity for the 
molasses than for the solid sugar, would, in its passage through the 
loaves, wash away the former, and leave the latter in its place, and 
that more weight and a closer grain would thus be obtained. The idea 
was ingenious, but the advantages scarcely counterbalanced the addi- 
tional expense of preparing the solution of fine sugar in the first in- 
stance. 
1555. Sugar may be obtained from the sap of many other plants. It 
•exists in large quantity in the sugar maple (acer saccharinurh), and in 
the root of the common beet (beta vulgaris). In many ripe fruits su- 
gar is a predominating ingredient ; and in dried grapes, figs, $-c., it is 
often seen as a superficial incrustation. Though thpse kinds of sugar 
differ a little from each other, they can scarcely be regarded as dis- 
tinct species. , * , 
1556. Honey is also a variety of sugar containing a crystallizable and 
an uncrystallizable portion, the predominance of one or other of which* 
give to it its peculiar chairacter ; they may be partially separated by- 
mixing the honey wifh alcohol, and pressing it in a linen bag ; the liquid 
sugar being the most soluble, passes through, leaving a granular mass, 
which forms crystals when its solution in boiling alcohol is set aside 
Honey also frequently contains wax, and a little acid matter. 
1557. Sugar is a white brittle substance of a pure sweet taste, so- 
luble in its own weight of water at 60°. Boiling water dissolves a con- 
siderably larger quantity.* This solution is called syrup; it is viscid, 
and furnishes crystals in the form of four and six-sided prisms, irregu- 
larly terminated. Sugar is soluble in alcohol, but much more sparing- 
ly so than in water. 
1558. Nitric and sulphuric acids decompose sugar*, the former coa- 
Charcoal. 
Saturated sy- 
rup. 
Sugar from ci- 
ther plants. 
Animal sugar. 
Honey. 
Action* of ELEMENTS OF SUGAR. 
verts it into oxalic acid ; the latter evolves charcoal and produces 
water and acetous acid. 
1559. The alcalis dissolve sugar, and destroy its sweet taste, which 
re-appears if an acid be added. When, however, the alcalis are left 
for a long time in the contact of sugar they effect a more important 
change, becoming carbonated and converting the sugar into gum. From 
a solution of sugar in lime-water, Mr. Daniell, who has obligingly fur- 
nished me with the principal materials of this section, obtained crys- 
tals of carbonate of lime and a portion of gum. The addition of plios- 
phuret of lime to syrup produces an analogous change.—Journal of 
Science and the Arts, Vol. vi. p. 32. 
1560. When protoxide of lead is digested with sugar and water, a 
portion is dissolved and afterwards separates in the form of a white in- 
sipid powder (saccharate of lead,) insoluble in water and composed, 
according to Berzelius, of 
Action of al- 
calis. 
Of protoxide 
of lead. 
Sugar 
. . 4-1.74 
Oxide of lead . . 
. . 58.26 
100.00 
Action of ca- 
loriy.-5 
1561. When sugar is exposed to heat it fuses, becomes brown, 
evolves a little water, and is resolved into new arrangements of its 
component elements. If suddenly elevated to a temperature of about 
500°, it bursts into flame. 
1562. The relative proportions of elements in gum and sugar ap- 
pear from the experiments of Gay-Lussac (page 17,) to be nearly the 
same. The analyses of these two substances by Berzelius afforded 
slight differences only ; according'to him they contain 
Carbon. . . . 41.906 
Oxygen . . . 51.306 
Hydrogen . . 6.788 
Gum. . 44.200 
= 100. . 49.015 
. . 6.785 
I Sugar 
> =r 100 
The equivalent of sugar, deduced from the analysis of the compound’ 
with oxide of lead, provided we regard that compound as containing J 
proportional of each of its components, is 80.2 a number not perfectly 
reconcileable with the ultimate of analysis of Berzelius, who regards 
sugar as composed of 
6 Proportionals of carbon. . 6X6 
= 36. .44. 4 
= 40. .49.38 
= 5. 6.17 
*81. 99.95 
Majma- 
1563. Manna is an exudation from the Fraxinus Ornus, a species of 
ash, growing in Sicily and Calabria. It has a sweet and somewhat 
nauseous taste, and is used in medicine as a mild aperient. It is very 
soluble in water, and more soluble in alcohol than cane sugar ; the lat- 
ter solution deposits it in the form of a white spongy mass. Digested 
in nitric acid, it yields both oxalic and saclactic acids. Its solution in 
•water does not appear susceptible of vinous fermentation. PROPERTIES OF STARCH. 
Section V. Starch. 
15G4. Starch, or Fecula, may be separated from a variety of vege- 
table substances ; it is contained in the esculent grains, and in man\ 
roots. The process for obtaining it consists in diffusing the powdered 
grain or the rasped root in cold water, which becomes white and tur- 
bid ; the grosser parts may be separated by a strainer and the liquor 
which passes deposits the starch, which is to be washed in cold water 
and dried in a gentle heat. 
1565. The common process for obtaining the starch of wheat con-] 
sists in steeping the grain in water till it becomes soft; it is then put 
into coarse linen bags, which are pressed in vats of water : a milky 
juice exudes, and the starch falls to the bottom of the vat. The super- 
natant liquor undergoes a slight fermentation, and a portion of alcohol 
and a little vinegar is formed, which dissolves some impurities in the 
deposited starch ; it is then collected, washed, and dried in a moderate 
heat, during which it splits into the columnar fragments which we meet 
with in commerce, and which are generally rendered slightly blue by a 
little smalt. 
1566. Pure starch is a white substance, insoluble in cold water, but- 
readily soluble at a temperature between 160° and 180°. Its solution' 
is gelatinous, becomes mouldy and sour by exposure to air, and by care- 
ful evaporation yields a substance resembling gum in appearance,, 
which is a compound of starch and water. Starch is insoluble in alco- c 
hoi and in ether, and occasions no precipitate in the greater number of 
metallic solutions ; in solution of suhacetate of lead, however, it occa-, 
sions a copious precipitate. The most characteristic property of starch c 
is that of forming a blue compound with iodine ; it may he obtained by i 
adding an aqueous solution of iodine to a dilute solution of starch. 
Sulphuric and nitric acids dissolve starch, and slowly decompose it, 
or resolve it into new compounds. Dilute nitric acid dissolves it with- 
out decomposition, forming a greenish solution, which deposits starch 
upon the addition of alcohol. It is slowly soluble in muriatic acid, and: 
insoluble in acetic acid. 
Potassa, triturated with starch, forms a compound which is soluble 
jn water. 1 
Infusion of galls occasions a precipitate in the solutions of starch,! 
which re-dissolves by heating the liquid to 120°. This property Dr.1 
Thomson considers as characteristic of starch. 
1567. By digesting subnitrate of lead in a boiling solution of starch, 
Berzelius obtained an insoluble compound, which he has termed amy~ 
late of lead, consisting of 
Process for ob i 
taining starchy 
Properties of 
starch. 
Insoluble in-al- 
cohol, doc. 
Precipitates 
oxide of lead. 
Forms a blue 
with iodine. 
Soluble in 
acids, 
Unites to ptH 
tassa. 
Precipitated! 
by tannin, 
72 starch. 
28 oxide of lead. 
100 
1568. It appears by a reference to the ultimate elements of starch 
and sugar, that they differ little in composition, and it is therefore not 
surprising that the former is easily convertible into the latter. 
1569. The change of starch into sugar is always observed during the ELEMENTS OF STARCH. 
Germination. 
germination of seeds (1534), and in the process of mailing a similar 
conversion is effected. 
Mall is barley which has been made to germinate to a certain extent, 
after which the process is stopped by heat. The barley is steeped in 
cold water, and is then made into a heap, or couch, upon the maltfloor : 
here it absorbs oxygen and evolves carbonic acid ; its temperature aug- 
ments, and then it is occasionally turned, to prevent its becoming too 
warm. In this process the radicle lengthens, and the plume, called by 
the maltsters the acrospire, elongates ; and when it has nearly reach - 
ed the opposite extremity of the seed, its further growth is arrested 
by drying at a temperature slowly elevated to 150° or more. The 
malt is then cleansed of the rootlets. 
According to Dr. Thomson, barley loses about 8 per cent, by con- 
verting it into malt, of which 
Malting-. 
1.5 
is carried off by the steep-water 
3.0 dissipated in the floor 
3.0 
roots separated by cleansing 
0.5 
waste 
8.0 
1570. The following comparative analysis of unmalted and malted 
barley shows the change which has taken place in the operation. 
Gum 
5 
Sugar 
. . . . 16 
Gluten .... 
3 
Starch .... 
88 
100 barley. 
100 malt. 
1571. Another mode of converting starch into sugar was discovered 
by M. Kirchoff ; it consists in boiling it with very dilute sulphuric acid. 
A pound of starch may be digested in six or eight pints of distilled wa- 
ter, rendered slightly acid by two or three drachms of sulphuric acid. 
The mixture should be simmered for a few days, fresh portions of wa- 
ter being occasionally added to compensate for the loss by evaporation. 
After this process the acid is saturated by a proper proportion of chalk, 
and the mixture filtered and evaporated to the consistence of syrup ; 
its taste is sweet, and, by purification in the usual way, it affords crys- 
tallized sugar. MM. de la Rive and Saussure have shown that the con- 
tact of air is unnecessary in the above process ; that no part of the 
acid is decomposed, no gas evolved, and that the sugar obtained exceeds 
by about one-tenth, the original weight of the starch. M. de Saussure, 
llierefore, concludes that the conversion of starch into sugar depends 
upon the solidification of water, a conclusion strengthened by the fol- 
lowing comparative analysis.—Thomson’s Annals, Vol. ii. 
Conversion of 
starch into su- 
gar by sulphu- 
ric acid. 
Carbon . . . 
Oxygen . . 
Hydrogen . 
Nitrogen . . 
100 Parts of Starch 
contain 
100 Parts of Starch 
Sugar contain 
100.00 
100.00 GLUTEN. 
1572. This analysis of starch is somewhat at variance with that 
given by Gay-Lussac ; indeed the small portion of nitrogen cannot be 
considered as an essential component. Berzelius has given the folldw- 
1 owing as the component parts of starch.—Thomson’s Annals, Xol. v. 
Carbon 
43.481 
Oxygen 
48.455 
Hydrogen .... 
7.064 
100.000 
If we regard the amylate of lead as consisting of 2 proportionals of 
starch, and 1 of oxide of lead, the number 144. will be the equivalent 
of starch, the constituents of which may be thus expressed : 
10 
Proportionals of carbon . . 
6 
X 
10 = 
60. . 
42.2 
9 
8 
X 
9 = 
72. . 
50.7 
10 
1 
X 
10 = 
10.0. 
7. 
142. 99.9 
These numbers closely approximate to the results of Gay-Lussac and 
Thenard’s analysis. 
1573. When starch is exposed to a temperature between 600° and 
700° it swells, and exhales a peculiar smell; it becomes of a brown co- 
lour, and in that state is employed by calico-printers under the name 
of British gum. It is soluble in cold water, and does not form a blue 
compound with iodine. Vauquelin found it to differ from gum in 
affording oxalic instead of mucous acid, when treated with nitric acid. 
1574. Proust has described a principle in barley, to which he has 
given the name of Hordein; it appears, however, to be a variety of 
starch, and can scarcely be admitted as a distinct vegetable principle. 
—Annales de Chimie et Phys. Tom. v. 
1575. The following are the principal varieties of starch : 
i. Arrow- root, the fecula of the Marantha Arundinacea. 
ii. Potatoe Starch, obtained by reducing potatoe to a pulp, and wash- 
ing it with cold water upon a sieve ; the fecula is deposited in the form 
of a fine white powder, heavier than common starch, but possessed of 
its essential characters. 
iii. Sago, extracted from the pith of several species of palm, gi’owing 
in the East India islands. 
iv. Tapioca and Cassava, prepared from an American plant, the 
latropha Manihat. 
v. Salop, obtained from the roots of several species of Orchis. 
British gum; 
Hordein. 
V arietieSi 
Section VI. Gluten. 
157G. Gluten may be obtained from wheat-flour, by forming it into 
a paste and washing it under a small stream of water. The starch is 
thus washed away, and a tough elastic substance remains, which is 
gluten. 
Extraction. NUTRITIVE INGREDIENTS OF VEGETABLES. 
Its colour is grey, and, when dried, it becomes brown and brittle. It. 
is nearly insoluble in water and in ether. When allowed to putrefy 
it exhales an offensive odour, and when submitted to destructive dis- 
tillation it furnishes ammonia, a circumstance in which it resembles ani- 
mal products. Most of the acids and the alcalis dissolve it. 
1577. Acted upon by alcohol, a portion of gluten is dissolved, and 
the solution, after having remained to deposit a little extraneous matter, 
affords, on evaporation, a peculiar substance of a yellowish colour, 
brittle, and having a balsamic taste. The undissolved portion of the 
gluten forms soapy compounds with the alcalis, and instead of ferment- 
ing like the original gluten, exhales the odour of putrid urine. Hence 
it appears that, by the action of alcohol, gluten is separated into two 
principles, the one soluble and the other insoluble in that menstruum. 
M. Taddei, the author of these researches, calls the former Gliadine, 
and the latter Zimoma.—Giornale di Fisica, ii. p. 360. 
1578. Gluten is an essential ingredient in wheat-flour, and contributes 
much to its nutritive quality ; and gives considerable tenacity to its 
paste. 
1579. A substance, much resembling gluten, has been found in the 
juices of certain vegetables, especially in those which are milky and 
coagulable by acids. It is contained in the sap of the houseleek, of 
the cabbage, and of most of the cruciform plants. Submitted to de- 
structive distillation, it affords ammonia, and is in other respects similar 
to the animal principle, called albumen ; hence it has been termed 
vegetable albumen. 
1580. Caoutchouc and Bird-lime may also be considered as allied to 
gluten. These substances are insoluble in water and in alcohol, but 
they are soluble in pure sulphuric ether. Caoutchouc is highly in- 
flammable, burning with a bright flame which throws off much char- 
coal. When heated it softens, and is in that state soluble in some of 
the fixed oils. It is said to dissolve easily in oil of cajeput. These 
solutions are sometimes used as varnishes, but with the exception of 
that in ether, they remain clammy. 
1581. The principles which have now been adverted to, viz., sugar, 
starch, gum or mucilage, and gluten, constitute the principal nutritive 
ingredients in most of the esculent vegetables. Wheat grown in this 
country contains from 18 to 24 per cent, of gluten, the remainder being 
principally starch. The wheat of the south of Europe generally con- 
tains a larger quantity of gluten, and is therefore more excellent for 
the manufacture of macaroni, vermicelli, and other preparations re- 
quiring a glutinous paste. The excess of gluten in wheat-flour com- 
pared with other grain, renders it peculiarly fit for making bread ; for 
the carbonic acid, extricated during the fermentation of the paste, is 
retained in consequence of its adhesiveness, and forms a spongy and 
light loaf. 
A hundred parts of barley contain upon an average 80 parts of starch, 
6 of gluten, and 7 of sugar, the remaining 7 parts being husk. 
From 100 parts of rye Sir Humphry Davy obtained 61 parts of starch 
and 5 of gluten. 
From 100 parts of oats he procured 59 of starch, 6 of gluten, and 2 
of sugar. 
100 parts of pease afforded about 50 of starch, 3 of sugar, 4 of glu- 
ten, and a small portion of extractive matter. 
Properties. 
Tbirtly soluble 
iu alcohol. 
Vegetable al- 
bumen. 
Bird-lime. HEMATIN. 
100 parts of potatoe yield, upon an average, 20 parts of starch ; they 
may be considered in general as containing from one-fourth to one-fifth 
of their weight of nutritive matter. 
The turnip, carrot, and parsnip, chiefly contain sugar and mucilage : 
1000 parts of common turnips give about 34 of sugar, and 7 of muci- 
lage ; 1000 parts of carrots furnish about 95 of sugar, and 3 of muci- 
lage ; and the same quantity of parsnips afford 90 of sugar and 9 of 
mucilage. The loss of weight in the above cases is referable to water, 
and inert vegetable matter possessed of the properties of woody fibre. 
{See the Table at the end of Section xviii. 
Section VII. Extractive Matter and Lignin. 
1582. By the term extract, or extractive principle ,we mean a substance 
contained in the greater number of vegetables, and generally forming 
the principal ingredient in the pharmaceutical preparations called ex- 
tracts. It possesses the following properties. It is soluble in water, 
and the solution is of a brown colour. It is insoluble in ether, but it 
is soluble in alcohol containing a small portion of water. By repeated 
solutions and evaporations it may be rendered scarcely soluble in wa- 
ter. Solutions of chlorine, of many of the acids, and of most of the 
metallic oxides, occasion precipitates in the aqueous solution of ex- 
tractive. 
1583. The following substances maybe considered under this head, 
though many of them are obviously widely different from extractive 
matter. 
1584. Ulmin. This substance was first noticed by Klaproth, spon- 
taneously exuding from the elm. From the observations of Berzelius, 
it exists in the bark of many other trees, and may be obtained by di- 
gestion in alcohol and cold water ; the action of hot water afterwards 
dissolves the ulmin.-r-THOMSON’s Annals, Vol. ii. 
Ulmin is of a dark brown colour, with scarcely any taste or smell. 
It is sparingly soluble in water and in alcohol, but readily soluble in a 
weak solution of carbonate of potassa. Very few of the metallic salts 
occasion a precipitate in its solution. The exudation from the elm is 
generally combined with carbonate of potassa, and is therefore readfiy 
soluble in water. 
1585. Polychroite. This term has been applied to the extract of saf- 
fron (Annales de Chim. Tom. lxxx.) It is of a deep yellow colour, deli- 
quescent, readily soluble in water and in alcohol, but insoluble in pure 
sulphuric ether. Exposure to the solar rays soon destroys the colour 
of its aqueous solution. Sulphuric acid renders it blue, and nitric acid 
green : solutions of lime and baryta produce yellow and red precipi- 
tates ; subacetate of lead throws down a deep yellow precipitate, and 
nitrate of mercury separates a red powder. 
1586. Hematin. This peculiar substance was first recognised by 
Chevreul in the colouring matter of log-wood {Ann. de Chim. Tojn> 
lxxxi.) It may be obtained by digesting logwood in water of the tem- 
perature of 125°. Filter, evaporate carefully to dryness, and digest 
Properties. BITTER PRINCIPLE, 4'C. 
the residue for 24 houi's in alcohol of the specific gravity of .837. 
Filter the alcohol ; concentrate the solution by evaporation,'add a por- 
tion of water, evaporate a little further, and set the solution aside : 
crystals are deposited which, when washed with alcohol and dried, are 
pure hematin. 
Hematin is of a reddish colour ; its taste is somewhat bitter, and its 
aqueous solution is yellow when cold, but orange-red at the tempera- 
ture of boiling-water. Sulphuric acid added to this solution renders it 
reddish yellow. The alcalis give it a purplish tint. 
1587. Bitter 'principle. By evaporating an infusion of quassia, a sub- 
stance is obtained of an intensely bitter taste, and of a brownish yel- 
low colour, which is readily soluble in water and in alcohol. Nitrate 
of silver, and acetate of lead, are the only precipitants of its aqueous 
solution. It is probable that the same substance exists in other bitter 
vegetables, and Vauquelin has discovered it in the fruit of the colocynth, 
and in the root of white hriony.—Thomson’s System, Vol. iv. 
1588. By digesting indigo, silk, and a few other substances in nitric 
acid, an intensely-bitter matter is formed, called by Welther the yellow 
hitter principle (Annales de Chim. Tom. xxix.) Chevreul has render- 
ed it probable that this is a compound of a peculiar vegetable princi- 
ple with nitric acid. It is crystallizable, burns like gunpowder and 
detonates when struck with a hammer. 
1589. Picrotoxin. This is a bitter poisonous substance contained in 
the Cocculus Indicus. It may be obtained by the following process :— 
Add acetate of lead to a decoction of the berries, as long as any preci- 
pitate falls : filter, evaporate, and digest the extract in highly-rectified 
alcohol ; evaporate to dryness, and agitate the remaining matter with a 
little water; the picrotoxin remains in the form of white prismatic crys- 
tals of a bitter taste. 
1590. Picrotoxin is difficultly soluble in water- Alcohol of the spe- 
cific gravity of 810, dissolves one-third its weight. It is soluble in 
weak solutions of tho puro alr.nlis. It combines with the acids, and 
forms compounds, some of which are crystallizable, but they require 
further examination before we can venture to give this substance a 
place among the narcotic salifiable bases.—Boullay, Journal de 
Pharmacie. v. 
1591. Nicotin. This is a principle existing in tobacco. It was ob- 
tained by Vauqelin by the following process (Ann de Chim. lxxi.) : 
Evaporate the expressed juice to one-fourth its bulk ; and, when cold, 
strain it through fine linen ; evaporate nearly to dryness ; digest the re- 
sidue in alcohol; filter and evaporate to dryness ; dissolve this again 
in alcohol, and again reduce it to a dry state. Dissolve the residue in 
water, and saturate the acid which it contains with weak solution of po- 
tassa, introduce the whole into a retort, and distil to dryness ; re-dis- 
solve, and again distil three or four times successively. The nicotin 
will thus pass into the receiver, dissolved in water, from which solution 
it may be obtained by very gradual evaporation. 
Nicotin is colourless, acrid, soluble in water and in alcohol, volatile, 
and highly poisonous. 
1592. Asparagin.—MM. Vauquelin and Robiquet obtained this sub- 
stance in a crystalline form by evaporating the juice of asparagus. It 
has a cool and slightly nauseous taste, and when burned emits acrid va- 
pours, and leaves no traces of alcali.—Annales de Chimie, Tom. iv. FUDGIN', INULIN, 4*C.. 
475 
1593. Fungin. This name has been given by Braconnot to a sub- 
stance contained in the fleshy part of mushrooms (Ann. de Chim. lxxix.) 
It is insoluble in water and in alcohol, and scarcely acted upon by the 
alcalis, or by dilute acids. It is the substance which remains after the 
mushroom has been deprived of every thing soluble in alcohol and in 
water. 
1594. Inulin. The roots of elecampane, when boiled in water, fur- 
nish a decoction, which, on cooling, deposits a white powder, in many 
respects resembling starch. It, however, differs in several proper- 
ties from that principle, and has hence been considered a peculiar ve- 
getable substance.—Thomson’s System, Vol. iv. 
1595. Emetin. To obtain emetin, digest powdered ipecacuanha in 
alcohol, filter, evaporate carefully to dryness, and re-dissolve in cold 
water. To this solution add carbonate of baryta, filter, and again eva- 
porate to dryness ; digest this residuum in alcohol, and a solution is ob- 
tained, which by careful evaporation, affords a reddish-brown substance, 
soluble in alcohol and in water, and precipitable by sub-acetate of lead ; 
its taste is acrid and bitter, and it is highly emetic.—MM. Magendie 
and Pelletier, Annalesde Chimie ct Physique, Vol. iv. 
1596. Woody fibre. The term lignin has been applied to the fibrous 
substance which remains, after digesting wood in water and in alcohol. 
It is insipid, and exposed to destructive distillation, affords a considera- 
ble quantity of vinegar tainted by empyreumatic oil, and containing a 
little ammonia. The charcoal which remains is light, brittle, shining, 
and easily incinerated. The relative quantity, yielded by different 
woods, has already been adverted to (386.) 
1597. We are indebted to M. Braconnot for some highly interesting 
experiments, relating to the action of sulphuric acid on wood (Ann. de 
Chim. et Phys. xii. 172.) In the course of these researches, he tritu- 
rated 25 parts of hempen cloth with 34 of the acid ; it acquired the 
consistency of mucilage, which, after 24 hours, was almost entirely 
soluble in water. The diluted liquor was saturated with chalk, fil- 
tered, and evaporated to the consistency of syrup ; it deposited sul- 
phate of lime, and was then further evaporated to dryness, when a 
substance, having the characters of gum, was obtained. In another ex- 
periment, 24 parts of lignin were reduced to gum by 34 of sulphuric 
acid ; this acid mixture, diluted with water, and boiled for 10 hours, 
became sweet; the acid was then separated by chalk, and the liquor, 
on due evaporation, afforded a crystallizable sugar. 
Moistened saw-dust, heated in a platinum crucible with its weight of 
caustic potassa, afforded a matter soluble in water, and which, upon the 
addition of an acid to neutralize the alcali, yielded a substance having 
the properties of ulmin. 
1598. Suber or Cork. This is a light, soft, elastic, and combustible 
substance, burning with a bright flame and leaving a bulky charcoal. 
Its principal peculiarity is, that by digestion in nitric acid, it is con- 
verted into an orange-coloured mass, which furnishes to water a pecu- 
liar acid matter, which has been termed suberic acid. Chevreul has 
found in it resin, oil, and a peculiar matter which he calls Cerin.—See 
Wax (1622.) 
1599. Cotton is a downy substance found in the seed-pods of the 
different species of gossypiurn. It is insoluble in water and in dilute 
alcalinc and acid solutions. It combines with several of the metaflic 476 
TANNIN. 
oxides, which are therefore used as intermedes, or mordants, in the 
art of dyeing. Acetate of alumina is principally employed for this 
purpose. 
1600. Medullin is a term given by Dr. John to the pith of the sun- 
flower and some other plants ; it is insipid, inodorous, insoluble in water 
and alcohol, and affords oxalic acid when treated by nitric acid ; sub- 
mitted to destructive distillation, the products abound in ammonia. 
Section VIII. Tannin. 
1601. TANlsiN, or the astringent principle, is contained in many ve- 
getables. It may be procured by digesting bruised gall-nuts, grape- 
seeds, oak-bark, or catechu, in a small quantity of cold water. The 
solution affords, when evaporated, a substance of a brownish-yellow 
colour, extremely astringent, and soluble in water and in alcohol. 
The purest form of tannin appears to be that derived from bruised 
grape-seeds, but even here it is combined with other substances, from 
which it is perhaps scarcely separable, and among the numerous pro- 
cesses which have been devised for procuring pure tannin, there is 
none that answers the intended purpose. I have never been able to 
obtain it of greater apparent purity than by digesting powdered catechu 
in water at 33° or 34°, filtering and boiling the solution, which, on 
cooling, becomes slightly turbid, and is to be filtered again, and eva- 
porated to dryness ; cold water, applied as before, extracts nearly 
pure tannin. 
1602. The most distinctive character of tannin is that of affording 
an insoluble precipitate when added to a solution of isinglass, or any 
other animal jelly. Upon this property the art of tanning depends, 
for wrhich oak-bark is generally employed; the barks, however, of 
many other trees may occasionally be substituted. The following 
Table, drawn up by Sir Humphry Davy, exhibits the average quantity 
of tan contained in 480 lbs. of different barks:—Agricultural Chemistry, 
4to. p. 79. 
Extraction. 
Properties. 
Average of entire bark of middle-sized Oak, cut in spring 
of Spanish Chestnut 
lbs. 
.... 29 
.... 21 
33 
.... 13 
11 
. . 16 
. _ 10 
9 
11 
15 
. . 9 
. . 14 
16 
• . . . 32 
. . 21 
. . 8 
White interior cortical layers of Oak-bark 
.... 72 
tJnioa with 
Other bodies. 
1603. Tan forms a precipitate with solution of starch, with gluten 
and albumen, and with many of the metallic oxides. An account of the COLOURING MATTER. 
477 
precipitates formed in metallic solutions by infusion of galls, will be 
found under the article Gallic Acid (1785) but these precipitates are 
very complex, and vary in composition. 
1604. If the solution of tan, obtained as above-described from cate- 
chu, be added to acetate of lead, an insoluble tannate of lead falls, 
composed, according to Berzelius, of 100 tannin -}- 52 oxide of lead. 
Now, if we suppose that tannin forms definite compounds with the me- 
tallic oxides, in the manner of a vegetable acid, the number 215.3 will 
be its representative, as deduced from the above datum. 
1605. Mr. Hatchett has shown that tan may be formed artificially by 
digesting charcoal in dilute nitric acid during several days ; it is at 
length dissolved, and a reddish brown liquor is obtained, which fur- 
nishes, by careful evaporation, a brown glossy substance, amounting to 
about 120 parts from 100 of charcoal. 
This artificial tannin appears to differ in one circumstance only from 
natural tannin, which is, that it resists the action of nitric acid, by 
which all the varieties of natural tannin are decomposed, though some 
are more capable of resisting its action than others. 
Artificial tannin has a bitterish astringent taste, is soluble in water and 
alcohol, and forms an insoluble precipitate in solutions of animal gela- 
tine, the precipitate consisting, according to Mr. Hatchett, of 
Metallic ox- 
ides. 
r Artificial tan- 
tnin. 
36 Tannin. 
64 Gelatine. 
100 
Muriatic and sulphuric acids occasion brown precipitates, in solution 
of artificial tan, which are soluble in hot water. It combines with the 
alcalis, and forms a precipitate of difficult solubility in aqueous solu- 
tions of lime, baryta, and strontia, and in most metallic solutions ; these 
precipitates are of a brown colour. 
1606. A variety of artificial tan is formed by digesting camphor and 
resins in sulphuric acid till the liquor becomes black, and on being 
poured into water, deposits a black powder, which, by digestion in al- 
cohol, furnishes a brown matter, soluble in water, and forming an in- 
soluble precipitate with gelatine.—Hatchett, Phil. Trans. 1805, 1806, 
Actions »f 
acids. 
Section IX. Colouring Matter. 
1607. The colouring matter of vegetables appears to reside in se- 
veral of their principles, and is therefore very differently acted on by 
solvents. Its extraction, and transfer to different substances, consti- 
tutes the art of Dyeing. 
1608. Different materials not only possess very different attractions 
for dye stuffs, but they absorb the colouring matter in very different 
proportions. Wool appears in this respect to have the strongest at- 
traction for colouring substances : silk comes next to it; then cotton ; 
and, lastly, hemp and flax. 
1609. Colours have been divided by Dr. Bancroft, in his work ort 
permanent Colours, into substantive and adjective. The former commu- 478 
INDIGO. 
nicate colour without the intervention of any other substance. They 
have an attraction for the fibre of cloth or linen, and are permanently 
retained. The latter require the intervention of some body, possess- 
ed of a joint attraction for the colouring material and stuff to be dyed. 
The substance capable of thus fixing the colour, has been called a ba- 
sis, or mordant. 
1610. The mordants most frequently employed are acetate of salu- 
mina, ulphate or acetate of iron, and muriate of tin. The substance to 
be dyed is first impregnated with the mordant, and then passed through 
a solution of the colouring matter, which is thus fixed in the fibre, and 
its tint is either modified or exalted by the operation. 
The following are the modes of producing some of the principal co- 
lours : 
1611. Black is produced by astringents and salts of iron, and if in- 
tended to be deep and perfect, the cloth should previously be dyed 
blue with indigo. The stuff is first soaked in a bath of galls, then rin- 
ced, and passed repeatedly through a solution of sulphate of iron in in- 
fusion of logwood ; exposure to air deepens the colour, which at first 
has a purplish tint. Logwood tends considerably to improve the black, 
and prevents its acquiring a rusty or brown hue. Sometimes madder 
is used for the same purpose. Silk is dyed black nearly in the same 
way, but it requires a much larger relative proportion of galls, and the 
operation must be frequently repeated. It is difficult to give a good 
and permanent black to calico; in this process, acetate of iron, galls, 
and madder are generally used, and the colour is rendered more dura- 
ble by previously steeping the goods in a weak solution of glue. 
Grey is produced by the same operations as black, but the materials 
are used in a very dilute state. 
1612. Blue is chiefly derived from indigo, a substance produced by 
fermenting the leaves of several species of the indigofera, a plant 
abundantly cultivated in South America and in the East Indies. 
1613. Indigo is a substance of a deep blue colour, containing about 
50 per cent, of pure colouring matter, which is perfectly insoluble in 
water ; when heated it sublimes in the form of a blue smoke, which on 
condensation, forms acicular crystals. It is soluble in concentrated 
sulphuric acid. This solution is usually called Saxon or liquid blue, and 
is used as a substantive colour for dyeing cloth and silk. Substances 
which powerfully attract oxygen render indigo green, and by exposure 
to air, it again acquires a blue colour. In this green state indigo is so- 
luble in the alcalis, and the solution is commonly employed for dyeing 
calico. A bath for this purpose may be made by mixing one part of 
indigo, two parts of sulphate of iron, and two of lime, in a sufficient 
quantity of water: in this case the sulphate of iron is decomposed by 
a portion of the lime. The protoxide of iron thus produced becomes 
peroxidized at the expense of the indigo, which is rendered green and 
soluble in the alcaline liquor ; cotton steeped in this solution acquires 
a green colour, which by exposure to air, and washing in water acidu- 
lated with sulphuric acid, becomes a permanent blue. 
A little iron or zinc thrown into diluted sulphate of indigo, changes 
or destroy* the colour in consequence of the evolution of hydrogen; 
the colour is also quickly impaired and destroyed by chlorine. 
1614. The analysis of indigo, to ascertain the proportion of colour- 
ing matter, which varies much in different samples, may be per- 
Mordants. 
Black. 
Gify. 
Blue. 
tndigo. COCHINEAL. 
479 
formed by the successive action of water, alcohol, and muriatic acid 
(Chevreul, Ann. de Chim. lxvi. 20.) 100 parts of Guatimala indigo, 
thus treated, afforded 
To Water . . 
Gteen matter combined with ammonia 
Deoxidized indigo 
Extract 
Gum 
> 12 
Green matter 
Resin 
A trace of indigo 
To Alcohol. 
30 
To’Muriatic 
Acid 
Red resin 
Carbonate of lime 
Oxide of Iron 
Alumina 
6 
2 
2 
Residue ... 
(Silica 
jPure indigo 
3 
45 
100 
1615. The action of nitric acid on indigo has been particularly exa.- 
Smned by Mr. Hatchett (Additional Experiments on Artificial Tan- 
nin, Phil. Trans. 1805.) This acid, diluted with about two parts of 
water, produces much effervescence when poured on powdered indigo, 
and gradually dissolves it; the solution, evaporated to dryness, leaves 
a yellow residue, soluble in water, of an intensely bitter taste, and 
composed partly of artificial Tannin, and partly of a peculiar bitter 
principle combined with ammonia. 
1616. Yellow. There are several dye stuffs employed in the produc-1 
tion of yellows. A decoction of Weld (Reseda Luteola,) with an alu- 
minous mordant gives a good yellow, which is rendered more brilliant 
by tartar, and by permuriate of tin. 
The bark of the American oak (Quercus Nigra,') or Quercitron bark, 
also furnishes excellent yellows ; it was first introduced into England 
by Dr. Bancroft, who has fully and philosophically detailed its various 
applications (Experimental Researches concerning the Philosophy of Per- 
manent Colours, &c., London, 1813.) The salts of alumina and of tin 
are the principal mordants employed both with wool and cotton. 
Fustic wood, sumach, and dyers’ broom, are also occasionally employ- 
ed as sources of yellow colours. 
1617. Reds are chiefly produced from madder, the prepared root of 
the Rubia Tinctorum. The colouring matter is fixed by an aluminous 
mordant, assisted by galls, but the process is very complex and circui- 
tous. In Dr. Bancroft’s work above quoted (Vol. ii.) are fall details 
upon this subject; and a perspicuous abstract-of them will be found in 
Aikin’s Dictionary, Art. Dyeing. 
Brazil wood, safflower, and logwood are occasionally employed as red 
or pink dye stuffs, but they only give fugitive colours. 
1618. Scarlet is produced exclusively with the colouring matter of 
the cochineal, a small insect brought from Mexico, where it is found 
upon different species of the Opuntia. The nature of this colouring 
matter has been investigated by MM. Pelletier and Caventou; it is 
united in the insect with a peculiar animal matter, fat, and some saline 
substances ; they separated it by exposing a strong alcoholic tincture of 
cochineal to spontaneous evaporation ; it deposited a crystalline mat- 
ter, which was re-dissolved in alcohol and the solution mixed with its 
bulk of sulphuric ether ; this caused it in a few days to deposit the 
pure colouring principle, which they call Carminium : Dr. John has 
Yellow. 
’Reds. 
Scarlet. 480 
calico-printing. 
proposed for it the term Coccinellin. This substance is fusible at 
about 120°, very soluble in water, less so in alcohol, and insoluble in 
ether ; the acids change its colour from purple to pale red or yellow : 
the alcalis render it violet; and its colour is impaired by most saline 
solutions. It readily combines with alumina, forming a beautiful lake 
or carmine. 
The colouring matter of cochineal is fixed upon wool by nitromuri- 
ate of tin and tartar, by which scarlets are produced, and alum changes 
the scarlet to crimson. Cotton and linen are very rarely dyed with 
cochineal, for independent of its great expense the colours are little 
superior to those given by madder. 
1619. Buff and Fawn Colour are produced in a variety of ways. 
Walnut-husks and Sumack, with alum mordants, give durable colours of 
this description, which are rendered Drab, or Grey, by a very little 
iron. 
1620. Green is obtained on woollen cloth, d>y passing it through the 
green indigo vat, and then dyeing it as for simple yellows, the rela- 
tive proportion of the blue and yellow being adjusted to the intended 
intensity of the green. Silk is first dyed yellow, and afterwards blued 
with indigo. Saxon green is done by dyeing yellow upon a Saxon blue 
ground. A solution of verdigris in vinegar is sometimes used to pro- 
duce a delicate green : pearlash is added before it is used, and the 
cotton previously impregnated with the alum mordant, is then passed 
through the mixture. 
Besides the above, an infinite variety of compound colours are form- 
ed, by mixtures of the simpler tints, and of the mordants ; but as my 
object is merely to give a general idea of the principles of the art of 
dyeing, I must refer the reader for practical details to the works ex- 
pressly upon the subject, and more especially to Dr. Bancroft’s Trea- 
tise already quoted. 
1621. Calico-printing is a more refined and difficult branch of the 
art of dyeing. In this process adjective colours are almost always 
employed. The mordants, the principal of which are acetate of alu- 
mina, and acetate of iron, are first applied to the calico by means of 
wooden blocks or copper plates, upon which the requisite patterns are 
engraved. The stuff is then passed through the colouring bath, and 
afterwards exposed on the bleaching ground, or washed. The colour 
flies from those parts which have not received the mordant, and is per- 
manently retained on those parts only to which the basis has been ap- 
plied : variety of colours is produced by employing various mordants, 
and different colouring materials. 
White spots upon a dark ground are sometimes produced by cover- 
ing the parts with wax, pipe-clay, or other materials, which prevent 
the contact of the colour ; or citric acid, thickened with gum, is ap- 
plied like a mordant with the block or plate, which prevents the re- 
tention of the colour. Sometimes the colour is discharged in places 
by the application of chlorine. 
Buff. 
Green. 
Calico-print- 
ing. FIXED OIL. 
Section X. Wax. 
1622. This principle exists in many plants ; it may be obtained by j 
bruising and boiling them in water : the wax separates and concretes 
on cooling. 
The berries of the Myrica cerifera, and the leaves and stem of the 
Ceroxylon afford considerable quantities of wax by this process (Bos- 
tock, Nicholson’s Journal, Vol. iv., Brande. Phil. Trans. 1811.) 
The glossy varnish upon the upper surface of the leaves of many 
trees is of a similar nature, and though there are shades of difference, 
these varieties of wax possess the essential properties of that formed 
by the bee. 
1623. Pure wax is colourless and insipid; its specific gravity isi 
about .96 : it is insoluble in water, and fusible at a temperature of 
about 150° ; at a higher temperature it is converted into vapour, and 
at a red heat it burns in the contact of air with a bright flame. It is 
sparingly soluble in boiling alcohol and ether, and is deposited as the 
solutions cool. The fixed oils, when assisted by heat, readily dissolve 
it, and form a compound of variable consistency, which is the basis ofi 
cerates and ointments. Some of the volatile oils also dissolve wax, 
when aided by heat. It is soluble in the fixed alcalis1, forming soapy 
compounds ; but the acids scarcely act upon it; hence the advantage 
of wax-lute, for the retention of corrosive vapours. 
1624. When bees’-wax, or myrtle-wax, are digested in boiling alco- 
hol, they afford, according to Dr. John, a soluble and insoluble portion ; 
he has called the former cerin, the latter myricin. Cerin is insoluble < 
in water and in cold alcohol and ether, but dissolves in those liquids 
when heated. Myricin is insoluble, under all circumstances, in alco-] 
hoi and ether. 
The term cerine has been applied by Chevreul to a principle resem- 
bling wax, which he separated from cork ; it is less fusible than wax, 
more soluble in alcohol, and partly converted into oxalic acid, by the 
action of nitric acid (1598). 
1625. According to Gay-Lussac and Thenard, 100 parts of wax con- 
sist of 81.79 carbon, 6.30 of the elements of water, and 11.91 of ex- 
cess of hydrogen ; these numbers may be considered as equivalent to 
Estraclion. 
Properties, 
Cerates. 
Ccrin. 
Bfy.icin. 
1 
Proportional of oxygen . 
= 8 . 
. 6.48 
20 
,, ,, carbon 
6 X 20 = 120 . 
. 82.2 
18 
„ „ hydrogen 
1 X 18 = 18. . 
. 12.32 
146 
100.00 
Section XI. Fixed Oil. 
1626. Fixed Oil is generally obtained by pressure from certain seeds, 
such as the almond, linseed, and many others, and from the olive. The 
specific gravity of the fixed oils, is usually a little below that of water. 
They are viscid ; insipid, or nearly so ; and generally congeal at a 
Extraction. SOAPS. 
temperature not so low as that required to freeze water. A few of 
them are solid at the ordinary temperature, and have been called vege- 
table butters. They are insoluble in. water, but by the aid of mucilage 
may be diffused through it, forming emulsions. They are for the most 
part sparingly soluble in alcohol and ether, though castor-oil dissolves 
in any quantity in those fluids.—Brande, Phil. Trans. 1811. 
1627. Olive oil is sometimes adulterated with that of certain seeds, 
which may be detected by the action of nitrate of mercury. For this 
purpose, 6 parts of mercury are dissolved without heat in 7.5 parts of 
nitric acid, specific gravity 1.36 ; this solution, shaken with olive oil, 
becomes solid in a few hours ; but if sophisticated with oil of grains, 
it does not solidify it. 
1628. If oil, which has been congealed by cold, be submitted to 
pressure between folds of bibulous paper, a dry, concrete, fatty matter 
is obtained, which Chevreul has called Stearine : the paper absorbs a 
fluid matter, which does not congeal at a much lower temperature, and 
which,, though it does not become rancid, acquires viscidity by expo- 
sure to air. This fluid part he has called Elaine. The relative pro- 
portions of these principles differ in the different oils.—Annales de 
Chiinie, Tom. xciii. xciv.—See Animal Oils. 
1629. These oils cannot be volatilized without decomposition, which 
takes place at a temperature of about 600°, and water is copiously 
formed, attended by the separation of carbonaceous matter, which 
causes the oil to blacken and grow thick ; a portion of acetic acid is 
also at the same time formed. If the vapour be collected it is found 
acrid, sour, and empyreumatic ; it was formerly employed in pharmacy, 
under the name of philosophers’ oil, and as it was often obtained by 
steeping a brick in oil, and submitting it to distillation, it was also called 
oil of bricks. Passed through a red-hot tube, the fixed oils furnish a 
very large proportion of carburetted hydrogen gas (435) ; and when 
burned in the wicks of lamps they suffer a similar decomposition, and 
water and carbonic acid are the products of their combustion. 
1630. The greater number of the fixed oils undergo little other 
change by exposure to air than that of becoming somewhat more vis- 
cid, and acquiring a degree of rancidity. In this state they contain 
free acid, and redden vegetable blues. Some few, such as linseed and 
nut-oil, and the oils of the poppy and hempseed, become covered with 
a pellicle, and when thinly spread upon a surface, instead of remaining 
greasy, become hard and resinous ; these are termed drxjing oils, and 
their drying quality is much improved by boiling them upon a small 
quantity of litharge. 
1631. The drying oils, and especially nut-oil, form the basis of print- 
ers’ ink, the history of which will be found in Lewis’s Phil. Commerce 
of the Arts. The oil is heated and set fire to, and after having been 
suffered to burn for half an hour is extinguished, and boiled till it ac- 
quires a due consistency ; in this state it is called Varnish, and is vis- 
cid, tenacious, and easily miscible with fresh oil, or with oil of turpen- 
tine, by which it is properly thinned, and afterwards mixed with about 
one-eighth part of lamp-black. 
i. 1632. The alcalis readily combine with the fixed oils, and form 
white compounds called Soap. Of these the most important is the 
soap of soda, which is thus made : Five parts of barilla are mixed with 
one of lime and a proper quantity of water In this way a ley, or so- 
Stearine. 
Elaine. 
Oil of bricks.' 
Drying oils. 
Action of al- 
calis. VOLATILE OILS. 
lution of caustic soda, is obtained, which is boiled in an iron pot with 
six parts of oil till the soap separates, which is accelerated by the addi- 
tion of common salt; it is then suffered more perfectly to congeal, and 
in a few days becomes hard enough to cut into forms (Aikin’s Dic- 
tionary, Art. Soap). The best soaps are made with olive oil and soda ;; 
in this country animal fat is usually employed for the common soaps, to 
which resin and some other substances are occasionally added. Soft 
Soap is a compound of potassa with some of the common oils ; even 
fish oil is often used. 
Soap furnishes a milky solution with water. It dissolves in alcohol, 
and the solution, if concentrated, is of a gelatinous consistency. By 
carefully distilling off the alcohol, a transparent soap is obtained. 
The acids and the greater number of salts decompose soap, forming 
in most cases a compound of difficult solubility ; hence hard waters 
are unfit for washing, in consequence of containing sulphate of lime ; 
hence also the alcoholic solution of soap is useful as a test for ascer- 
taining the fitness of water for this purpose, which, if it becomes very 
turbid, cannot in general be used for washing. 
When soaps are decomposed by the acids, the oil which they con- 
tain is found to have undergone a change, the history of which will be 
noticed under the head of animal oils. 
1633. The fixed oils readily combine with oxide of lead, when 
aided by heat, forming the compound usually termed plaster; with the 
oxides of mercury and bismuth they produce very similar combina- 
tions, and are also capable of dissolving white arsenic in large pro- 
portion. 
1634. The ultimate components of olive oil, as given by Gay-Lussac 
and Thenard, are 
Soap. 
Plasters. 
77.21 
carbon. 
9.43 
oxygen. 
13.36 hydrogen. 
100. 
Section XII. Volatile Oils. 
1635. These oils are generally obtained by distilling the plants 
which afford them with water in common stills ; the water and oil pass 
over together, and are collected in the Italian recipient shown in the 
following cut, in which the water having reached the level a b, runs 
off by the pipe c, and the oil being generally lighter than water, floats 
upon its surface in the space d. The whole 
contents of the recipient are then poured into a 
funnel, the tube of which is closed with the fin- 
ger, and when the oil has collected upon the 
surface, the water is suffered to run from it, and 
the oil transferred into a bottle. The distilled 
water being saturated with the oil, should be re- 
tained for a repetition of the distillation. The 
produce of oil is sometimes increased, by add- 
ing salt to the water in the still, so as to ele- 
vate its boiling point a few degrees. 
> Extraction. VOLATILE OILS. 
Some of the volatile oils are obtained by expression, such as those 
of lemon orange, and Bergamot, which are contained in distinct vesi- 
cles in the rind of those fruits. 
1636. The volatile oils vary considerably in specific gravity, as 
shown by the following Table : 
Oil of Sassafras . . 
Cinnamon 
Cloves 
Fennel 
... 997 
Dill 
... 994 
55 
Penny-royal 
)) 
Cummin 
... 975 
55 
Mint . . 
... 975 
5) 
Nutmegs 
... 948 
55 
T ansy 
55 
Caraway 
... 940 
55 
Origanum 
... 940 
Spike 
. . . 936 
55 
Rosemary 
... 934 
55 
Juniper 
55 
Oranges 
... 888 
?> 
Turpentine 
... 792 
I 1637. The volatile oils have a penetrating odour and taste, and are 
generally of a yellowish colour ; they are for the most part very so- 
luble in alcohol, and very sparingly soluble in water ; these solutions 
constitute perfumed essences and distilled waters. The latter are prin- 
cipally employed in pharmacy, and the former as perfumes. 
When pure they pass into vapour at a temperature somewhat above 
that of 212°, but when distilled with water, they pass over at its boiling 
point. They are very inflammable, and water and carbonic acid are 
the results of their perfect combustion. As many of these oils bear a 
very high price, they are not unfrequently adulterated with alcohol and 
fixed oils. The former addition is rendered evident by the action of 
water ; the latter by the greasy spot which they leave on paper, and 
which does not evaporate when gently heated. 
1638. The volatile oils absorb oxygen, when long exposed to it, and 
become thick and resinous. They also absorb chlorine. Nitric and 
sulphuric acids rapidly decompose the volatile oils : a mixture of four 
parts of nitric, and one of sulphuric acid, poured into a small quanti- 
ty of oil of turpentine, produces instant inflammation, and muriatic 
acid is produced, along with a peculiar substance, in some cases not 
unlike camphor. Iodine produces changes somewhat analogous. Mu- 
riatic acid combines with several of them, and forms a crystallizable 
compound which has been compared to camphor (1647). 
1639. The relative quantity of essential oils, furnished from differ- 
ent materials, is liable to much variation ; the following are the pro- 
ducts of 1 cwt. of the different vegetable substances : 
Properties. Jg 
Action of oxy- 
gen. 
Chlorine. 
Juniper-berries (common) 
Ounces. 
Ditto (fine Italian) 
Aniseed (common) ........ 
®itto (finest') . . CAMPHORIC ACID. 
Caraways 
lbs. OZ. 
3 12 
to 
lbs. oz. 
4 12 
Dill-seed 
2 
to 
2 6 
Cloves 
18 
to 
20 
Pimento . 
2 
to 
3 4 
Fennel-seed 
2 
Leaves of the Juniperus Sabina . 
14 
Secttion XIII. Camphor. 
1640. This substance in many respects resembles the essential oils ; 
like them it is volatile, inflammable, soluble in alcohol, and sparingly 
soluble in water. 
In its ordinary state it is white, semi-transparent, and concrete. Its 
specific gravity .98. It fuses at about 300°, in close vessels. It dis- 
solves in the fixed and volatile oils. It is scarcely acted upon by the 
alcalis ; some of the acids dissolve, others decompose it.—Hatchett, 
Phil. Trans. 1803. Chf.vreul, Annales de Chimie, lxxiii. 
If mixed with bole or powdered clay, and repeatedly distilled, it is 
almost entirely converted into a liquid, having the characters of essen- 
tial oil. 
The camphor of commerce is obtained from the Laurus Camphora, 
and comes chiefly from Japan. It is originally separated by distilla- 
tion, and subsequently purified in Europe in a subliming vessel some- 
what of the shape of a turnip, from which the cakes of camphor de- 
rive their form. 
1641 When camphor is repeatedly distilled with nitric acid it is 
converted into camphoric acid. For this purpose four ounces of cam- 
phor, reduced to powder by triturating it with a few drops of spirit of 
wine, may be introduced into a two-quart tubulated retort, placed in a 
sand heat : pour upon it 30 ounces of common nitric acid, and proceed 
to slow distillation. When two thirds of the acid have passed over, 
return it into the retort and distil as before, repeating the operation 
twice more ; after which, as the liquor cools, a quantity of crystals of 
camphoric acid are deposited, which are to be washed and dried. This 
acid assumes the form of plumose crystals, soluble in about 100 parts 
of water at 60°, and in rather more than one part of alcohol. Its 
taste is acid, and somewhat acrid, and it has an aromatic odour. Ex- 
posed to heat it sublimes unaltered. It combines with the salifiable 
bases, constituting a class of salt called Camphorates. 
1642. Carnphorate of ammonia is with difficulty crystallized ; it is 
sparingly soluble in water, but more copiously in alcohol. 
1643. Carnphorate of Potassa forms hexagonal crystals, soluble in 
about 100 parts of water at 60°, and in 25 parts at 212°. Its alcohol- 
ic solution burns with a blue flame. 
1644. Carnphorate of Soda is possessed nearly of the same proper- 
ties as the preceding. 
1645. Carnphorate of Lime is nearly insoluble in water and alcohol. 
1646. Carnphorate of Baryta forms difficultly soluble lamellar crys- 
tals.—Bouillon Lagrange, Annales de Chimie, xxvii. 
i Soluble in al- 
r cohol. 
> Specific gravi- 
ty. 
i Action of oils. 
, Extraction. 
5 Action of ni- 
tric acid. 486 
RESINS. 
1647. When a current of muriatic acid gas is passed through oil of 
turpentine, it deposits a concrete substance, which has been called ar- 
.tificial camphor, and the weight of which amounts to about one-half of 
the oil employed. When purified by sublimation with a little quick- 
lime, it is rendered pure and white. It is lighter than water, sublimes 
without decomposition, burns like camphor, and in smell resembles 
a mixture of camphor and turpentine (Thenard, Mimoires 
Tom. ii.) By the action of zinc it affords chloride of zinc, and the oil 
is evolved little altered. 
1648. Camphor dissolves in sulphuric acid, forming a brown solu- 
tion, from which it is at first precipitated, unaltered, by water. Sul- 
phurous acid is afterwards evolved, the solution becomes black and 
thick, and, after some days, affords a brown coagulum on the addition 
of water, and smells fragrant and peculiar. On distilling the diluted 
liquor, water and a yellow oil pass over, a little sulphurous acid is then 
disengaged, and a black matter remains in the retort, which, when di- 
gested in alcohol, affords a portion of soluble matter having some of 
the properties of artificial tannin.—Hatchett, Phil. Trans. 1805. 
Artificial cam- 
phor. 
.Action of sul- 
phuric acid. 
Section XIV. Resins. 
1649. Resins are substances which exude from many trees, either 
from natural fissures or artificial wounds. Common resin is obtained 
by distilling the exudation of different species of fir ; oil of turpentine 
passes over, and the resin remains behind. It may be taken as a per- 
fect example of resin, and is possessed of the following properties : It 
is solid, brittle, a little heavier than water, and acquires negative elec- 
tricity when rubbed. It has scarcely any taste or smell ; is insoluble 
in water ; readily soluble in alcohol, which takes up about one-third 
its weight, and becomes milky upon the addition of water. Resin is 
soluble in the caustic alcalis, the solution is saponaceous, and when 
mixed with an acid, the resin separates, scarcely altered in its proper- 
ties. Nitric, muriatic, and acetic acids dissolve it without much change*. 
1650. A few of the resins derive odour from containing essential oil; 
some afford benzoic acid when heated, and these have been termed 
balsams; copal, mastich, and a few others, are very difficultly soluble 
in alcohol, and contain a substance somewhat analogous to caoutchouc. 
Guaiacum is characterized by the singular changes of colour, which its 
alcoholic solution suffers when exposed to the action of nitric acid.— 
Phil. Trans. 1811. 
Guaiacum is also rendered blue by the gluten of wheat, but its colour 
is not changed by starch ; the intensity of the blue colour is said to be 
proportional to the quantity of gluten present in flour.—Taddei, Gi- 
ornale de Fisica, i. 168. Quarterly Journal, viii. 376. 
Properties. 
Balsams. 
* The properties of the resins have been very ably investigated by Mr. Hatchett, the details 
«f whose researches will be found in his communications to the Royal Society, printed in the 
Philosophical Transactions for 1804, 1805, 1806. 1651. Lac is a substance formed by an insect, and deposited on dif- 
ferent species of trees chiefly in the East Indies. The various kinds 
of lac distinguished in commerce, are stick lac, which is the substance 
in its natural state, investing the small twigs of the tree : seed-lac, which 
is the same broken off; and which, when melted, is called shell-lac. 
These substances have been examined by Mr. Hatchett*. The follow- 
ing table exhibits their component parts.—Phil. Trans. 1804. 
AMBER. 
Stick-Lac. 
Seed-Lac. 
Shell-Lac 
Resin 
68 . 
. . . 88.5 . 
. . . 90.9 
Colouring matter 
10 . 
. . . 2.5 . 
... 0.5 
Wax ...... 
6 . 
. . . 4.5 . 
... 4.0 
Gluten 
5.6 . 
... 2.0 . 
... 2.8 
Foreign bodies . 
6.5 . 
. . . . 
. . . 
Loss 
4.0 . 
... 2.5 . 
. . . 1.8 
100 
100 
100 
1652. Dr. John has announced the presence of a peculiar acid ini 
stick-lac, which he has called Laccic Acid. The lac was digested in 
water, the solution evaporated, and the residue digested in alcohol: 
the alcoholic solution was evaporated to dryness, and its residue digest- 
ed in ether. The evaporation of the etheric solution leaves a yellow 
matter, which, being again dissolved in alcohol, and the solution mixed 
with water, deposits a little resin, and leaves laccic acid in solution, 
which, upon the addition of acetate of lead, gives a precipitate of lac- 
cate of lead; the latter compound, by cautious decomposition by sul- 
phuric acid, affords the laccic acid. 
1653. Laccic acid is crystallizable, of a yellow colour, a sour taste, 
and soluble in water, alcohol, and ether. With potassa, soda, and lime, 
it forms deliquescent soluble salts ; with lead and mercury it produces 
white insoluble compounds ; it occasions no precipitate in the nitrates 
of baryta and silver.—Thomson’s System, ii. 177. 
1654. Gum Resins are natural combinations of gum and resin, they 
are consequently only partially soluble in water and in alcohol; they 
readily dissolve in alcaline solutions when assisted by heat ; and the 
acids act upon them nearly as upon the resins. Ammoniacum,gamboge, 
assafcetida, and olibanum, may be taken as examples of gum resins. 
1655. Amber is a substance which, in some of its properties, resem- 
bles resin ; it is however, very sparingly soluble in alcohol, and diffi- 
cultly soluble in the alcalis. When submitted to distillation, it furnishes 
an acid sublimate, which has received the name of succinic acid, and 
which, when purified by repeated solutions and crystallization, pos- 
sesses the following properties :— 
1656. It forms yellowish prismatic crystals soluble in 24 parts of 
water at 60°, and of a slightly acid and nauseous taste ; it is fusible and 
volatile when heated. 10 lbs. of amber yield about 3 ounces of puri- 
fied succinic acid. Along with the succinic acid there distils over a 
quantity of volatile oil, of a light brown colour, used in pharmacy under 
Laccic Acid; 
Properties* 
* Dr, Pearson obtained a peculiar acid from a substance called while lac, from Madras 
He has called it laccic acid.—Phil, Trans. J 794. 488 
succinates of iron, zinc, copper, #c. 
the name of Oil of Amber, and amounting to about one-third in weight 
of the amber used. 
1657. Succinate of Ammonia forms acicular crystals, which sublime 
when cautiously heated. Its solution has been used as a test for iron, 
the peroxide of which it throws down from its neutral solutions in the 
form of a reddish brown precipitate. 
1658. Succinate of Potassa is a very soluble deliquescent salt, crys- 
tallizable with difficulty in small prisms. 
1659. Succinate of Soda forms transparent four and six-sided prisms, 
considerably less soluble than the preceding, and permanent in the air. 
1660. Succinate of Lime forms permanent and diffioulty soluble 
crystals. 
1661. Succinate of Baryta is formed by adding succinate of ammo- 
nia to muriate of baryta. A portion is thrown down in a pulverulent 
form, and a part in small crystalline grains.—Bergman. 
1662. Succinate of Strontia may be formed as the preceding, and 
presents similar properties. It burns with a fine red flame. 
1663. Succinate of Magnesia is deliquescent and uncrystallizable. 
1664. Succinate of Manganese has been examined by Dr. John 
(Gehlen’s Journal, iv.) It is crystallizable, and of a slight red tinge ; 
it consists of 30.27 protoxide of manganese + 69.73 acid and water. 
The theoretical constitution of succinate of manganese is 
50 acid 
36 oxide. 
so that the above salt is probably a bi-succinate. 
1665. Succinate of Iron. The protosuccinate is crystallizable and 
soluble ; the per succinate is insoluble, and is thrown down in the form 
of a brownish red flaky precipitate from solutions of the peroxide of 
iron. This salt has been proposed as a means of separating iron in 
analysis, but is quite inapplicable in the greater number of cases. 
1666. Succinate of Zinc furnishes long slender crystals, which have 
not been examined. 
1667. Succinate of Tin. The succinic acid dissolves protoxide of 
tin, and forms with it thin broad transparent crystals. 
1668. Succinate of Copper. There appear to be two varieties of 
this salt, a super-succinate and a sub-succinate. (For details respect- 
ing several of the succinates, the reader is referred to Wenzel’s Lehre 
der Verwandtschaft der Korper ; and to Gren, Handbuch, iii. 19.) 
1669. Succinate of Lead. When succinic acid, or succinate of am- 
monia, is added to acetate of lead, a white precipitate of succinate of 
lead falls, composed, according to Berzelius, of 
Succinic acid 
Protoxide of lead..... 
100. 
These numbers give 50 as the representative of succinic acid, and, 
considering the succinate of lead as composed of 1 proportional of 
each of its components, it will consist of 
Succinic acid 
Protoxide of lead.... 
. . . 112 
162 SALTS OF MORPHIA. 
489 
The remaining succinates are not of sufficient importance to re- 
quire enumeration. 
1670. The resins are applied to a variety of useful purposes ; and 
dissolved in alcohol and oils they constitute the different varnishes. 
Section XV. Narcotic Principles. 
1671. The substance to which the narcotic power of opium is re- 
ferable, has been examined with much attention by M. Serteurner ; he 
has termed it morphia. 
Morphia may be obtained from powdered opium by triturating it into 
a paste with dilute acetic acid : pour caustic ammonia into the filtered 
solution, and evaporate ; during the evaporation a brownish substance 
separates, which, by digestion in a small quantity of cold alcohol, be- 
comes nearly colourless, and is pure morphia. 
Morphia is sparingly soluble in water, but readily soluble in alcohol 
and in ether, from which it may be obtained in quadrangular and octoe- 
dral crystals. It is highly poisonous and narcotic, even when adminis- 
tered in very small doses ; it is fusible and combustible. 
Morphia appears in some respects to possess the properties of an 
alcali; it reddens turmeric, and forms crystallizable compounds with 
the acids. 
1672. Nitrate of Morphia forms acicular crystals, soluble in 1.5 of 
water, at 60°. 
1673. Sulphate of Morphia crystallizes in prisms, soluble in two 
parts of water, at 60°, and composed, according to Pelletier and Ca» 
ventou (Journal de Pharmacie, v.) of 
Extracting 
11 Sulphuric acid. 
89 Morphia. 
100 
1674. Carbonate of Morphia forms prismatic crystals, soluble in 4 
parts of water, at 60°, and containing, according to Choulant (Annals 
of Phil, xiii.) 
28 Carbonic acid. 
22 Morphia. 
50 Water. 
100 
These salts have a bitter taste, and are decomposed by ammonia j 
they have, however, been but imperfectly examined. 
1675. In opium morphiais said to be combined with a peculiar acid, 
which has been called the meconic acid, and this combination is decom- 
posed by the action of ammonia in the preparation of morphia. 
The following process is said to afford pure meconic acid : Boil in- 
fusion of opium with magnesia, and digest the precipitate in alcohol j 
meconiate of magnesia remains : dissolve this in dilute sulphuric acid. 
Msoonic aei i 490 
STRYCHNIA. 
and add muriate of baryta, a precipitate falls, composed of sulphate 
and meconiate of baryta; digest this in dilute sulphuric acid, which de- 
composes the meconiate : filter and evaporate, till brown crystals of 
impure meconic acid are deposited ; dry these crystals, and then heat 
them carefully in a retort, to sublime the meconic acid. White crys- 
tals are thus obtained, which fuse at 250°, and sublime without decom- 
position ; they are sour, and very soluble in water and alcohol. 
1676. Meconiate of Ammonia forms stellated crystals, soluble in 
1.5 parts of water, at 60°, and composed, according to Choulant, ©f 
42 Ammonia. 
40 Meconic acid. 
18 Water. 
100 
1677. Meconiate of Potassa forms four-sided tables, soluble in 2 
parts of water at 60°, and composed of 
60 Potassa. 
27 Meconic acid. 
13 Water. 
100 
1678. Meconiate of Soda forms efflorescent prismatic crystals, solu- 
ble in 6 parts of water at 60°, and composed of 
40 Soda. 
32 Meconic acid. 
28 Water. 
100 
1679. Meconiate of Lime affords prismatic crystals, soluble in 8 parts 
of water at 60°, and consisting of 
42 Lime. 
34 Acid. 
24 Water. 
100 
The equivalent number of meconic acid, deduced from the mean of 
the above analyses, by Choulant, will be about 23. 
1680. MM. Pelletier and Caventou, in analyzing the bean of St. Ig- 
natius (Strychnos Ignatia), and the vomica nut (Strychnos nux vomica), 
discovered in them a peculiar principle, which they have termed 
Strychnine, and which, like morphia, possesses alcaline properties. 
The following is their process for obtaining it: Digest the raspings of 
the bean in sulphuric ether, which separates a green oily fluid ; pour 
this off, and treat the residuum with alcohol; filter the latter solution 
when cold, and evaporate ; it leaves a brown bitter substance, soluble 
in water and alcohol; to its strong aqueous solution add a solution of po- 
tassa, which causes a precipitate, which, when washed with a little cold 
Strychnin*. water, is white, crystalline, and very bitter. If not quite pure, it 
may be rendered so by solution in acetic'acid, and precipitation by po- 
tass a. 
1681. Strychnine, or Strychnia, is nearly insoluble in water ; it dis- 
solves in alcohol, and the solutions are intensely bitter and poisonous. 
It reproduces the blue of vegetable colours reddened by acids. It 
crystallizes in small quadrangular prisms ; it has no smell, and is nei- 
ther fusible nor volatile, but is decomposed at about 600° into pro- 
ducts consisting of oxygen, hydrogen, and carbon. 
1682. The Salts of Strychnia are decomposed by potassa, soda, am- 
monia, baryta, strontia, and magnesia, the base being thrown down ; 
most of the other metallic salts are decomposed by strychnia, and with 
some it forms triple salts. 
1683. Sulphate of Strychnia forms cubic crystals, soluble in about 
10 parts of water at 60° ; its taste is bitter, and it is decomposed by 
the alcalis. It consists of 
DELPHINE. 
Sulphuric acid . . . 
Strychnia 
100. 
1684. Muriate of Strychnia crystallizes in acicular prisms more 
soluble than the sulphate. 
1685. Nitrate of Strychnia is formed by digesting excess of strychnia 
in very dilute nitric acid; it yields stellated crystals, which acquire a 
red colour by the action of sulphuric acid. Nitric acid poured upon 
strychnia or its salts produces a deep red colour. 
1686. The discoverers of strychnia assert that it exists in the above- 
mentioned seeds, combined with a peculiar acid, somewhat resembling 
the malic, but susceptible of crystallization ; they have called it Iga- 
suric Acid, and the poisonous principle existing in the seeds, appears 
to be an igasurate of strychnia. 
1687. Brucine. This term has been applied to a peculiar alcaline 
substance, obtained from Angustura bark, by the above-named che- 
mists. Its properties, as far as they have been investigated, are de- 
scribed in the Annales de Chimie (xii. p. 113.) and in the Quarterly 
Journal of Science and the Arts (ix. 189). 
1688. Delphine is an alcaline principle, discovered by MM. Las- 
saigne and Feneulle in the seeds of stavesacre (.Delphinium Staphysag- 
ria). They obtained it by the following process : The seeds, depriv- 
ed of their husks, were boiled in distilled water, the decoction filtered, 
boiled with a portion of pure magnesia, and re-filtered; the residue 
upon the filter was then boiled with highly rectified alcohol, by which 
the alcali was separated and obtained by evaporation in the form of a 
white pulverulent substance. 
Delphine, when pure, appears crystalline in its moist state ; its 
taste is bitter and acrid ; when heated, it melts, and on cooling becomes 
brittle like resin ; it is sparingly soluble in water, but readily soluble 
in alcohol and ether ; it renders the blue of violets green, and forms 
very soluble salts with the acids, from which the alcalis precipitate 
delphine in a white gelatinous state.—Annales de Chimie et Phys., xii. 
358. 492 
RETINASPHALTUM 
Section XVI. Bitumens, coal, ■S'C. 
1689. Bitumens are fossile substances, bearing considerable re= 
semblance to oily and resinous bodies. The chemical habitudes of se- 
veral of these substances have been ably investigated by Mr. Hatchett. 
(Phil Trans., 1804.) The following are the principal varieties : 
a. Naphtha is a pungent, odoriferous, oily liquid, either colourless 
or of a pale brown tint, found upon the borders of the Caspian Sea, 
and in certain springs in Italy. It is considerably lighter than water, 
volatile, and highly inflammable. When pure it appears to contain no 
oxygen, and hence is employed for the preservation of potassium, and 
the other highly oxidable metals. It consists, according to Saussure, 
of 
Carbon ..... 
Hydrogen .... 
100. 
b. Petroleum has most of the properties of naphtha, but is less fluid, 
and darker coloured. In the countries where it abounds, it is employ- 
ed for burning in lamps. 
c. Mineral Tar appears to be petroleum further inspissated. It is 
more viscid, and of a deeper colour. 
d. Maltha, or Mineral Pitch, is a soft inflammable substance, heavier 
than water, and may be considered as derived from the exsiccation of 
mineral tar. 
e. Asphaltum is found abundantly on the shores of the Dead Sea, in 
Albania, and in the island of Trinidad. Its colour is brown or black ; 
it is heavier than water, and readily soluble in naphtha. 
f. Elastic Bitumen, or Mineral Caoutchouc, is found only in the vici- 
nity of Castleton in Derbyshire. It is fusible and inflammable. 
g. Mineral Adipocere is a fatty matter found in the argillaceous iron 
ore of Merthyr : it is fusible at about 160°, and inodorous when cold, 
but of a slightly bituminous odour when heated, or after fusion. 
The above substances are insoluble in water, and difficultly soluble 
in alcohol, with the exception of naphtha and petroleum, which are 
soluble in highly-rectified alcohol. 
h. Retinasphaltum is a substance which accompanies the Bovey 
Coal of Devonshire. It was first analyzed by Mr. Hatchett, who 
found it to consist of 
55 Resin. 
41 Asphaltum. 
4 Earthy matter and loss. 
*• Pit Coal. There are three chemical varieties of this important 
substance, The first, or brown coal, retains some remains of the ve- 
getables from which it has originated. When heated it exhales a bitu- 
minous odour, and burns with a clear flame. It is generally of a tough 
consistency and yields according to Mr. Hatchett, a portion of unalter- 
ed vegetable extract, and resin. VEGETABLE ACIDS. 
493 
The second variety, or black coal, is the ordinary fuel of this coun- 
try. It exhibits no traces of vegetable origin, and consists principally 
of bitumen and charcoal, in variable proportions. When exposed 
to heat, it swells, softens, and burns with a bright flame, leaving a small 
quantity of ashes. Many varieties, however, abound in earthy matter, 
and these produce copious cinders, and burn with a less intense heat. 
The products of the destructive distillation of this kind of coal have 
been already described (431). The residue is a hard sonorous char- 
coal, termed coke, and containing the earthy ingredients of the coal. 
The third variety, or glance coal, consists almost entirely of char- 
coal, and earthy matter. It burns without flame, and when distilled 
produces scarcely any gaseous matter. 
k. Peat and Turf consist principally of the remains of vegetables, 
having undergone comparatively little change. They often contain 
bituminous wood, and branches and trunks of trees. 
l, Mellilite, or Honeystone, is a rare substance, found in the brown 
coal of Thuringia and in Switzerland. It is of a honey yellow colour, 
crystallized in octoedra, and when analyzed by Klaproth, was found to 
consist of alumina combined with a peculiar body which has been call- 
ed the mellitic acid.—Klaproth’s Essays, ii. 89. Vauq,uelin. An- 
nales de Chimie, xxxvi. 203. 
Section XVII. Vegetable Acids. 
1690. The following are the principal acids, which are found rea- 
dy formed in vegetable products : 
1. Tartaric acid. 
2. Oxalic acid. 
3. Citric acid. 
4. Malic acid. 
5. Gallic acid. 
6. Benzoic acid. 
i. Tartaric Acid. 
1691. This acid exists in several vegetable substances ; it is one of 
the sour principles of many fruits, and is said to be abundant in the 
potatoe-apple. Tartaric acid is generally obtained from the bi-tartrate] 
of potassa. Mix 100 parts of this salt in fine powder with 30 of pow- 
dered chalk, and gradually throw the mixture into 10 times its weight 
of boiling water : when the liquor has cooled, pour the whole upon a 
linen strainer, and wash the white powder which remains with cold 
water : this is a tartrate of lime; diffuse it through a sufficient quantity 
of water, add sulphuric acid equal in weight to the chalk employed, 
and occasionally stir the mixture during 24 hours ; then filter, and 
carefully evaporate the liquor to about one-fourth its original bulk ; 
filter again, and evaporate with much care nearly to dryness ; re-dis- 
solve the dry mass in about 6 times its weight of water, render it clear 
by filtration, evaporate slowly to the consistency of syrup, and set aside 
to crystallize. By two or three successive solutions and crystalliza- 
tions, tartaric acid will be obtained in colourless crystals, soluble in 6 
parts of water at 60°. According to Berzelius, the crystals contain 
, Mode of 6b- 
taioing. 494 
TARTRATES OF rOTASSA. 
11.25 per cent, of water. The aqueous solution of tartaric, in com- 
mon with the other vegetable acids, soon becomes mouldy, and suffers 
decomposition. 
1692 When tartaric acid is submitted to destructive distillation, it 
affords a brown acid liquor which has been termed pyrotartarous acid. 
1693. According to Berzelius, the tartrate of lead, which is an inso- 
luble salt, and easily formed by adding tartaric acid to a solution of ni- 
trate of lead, consists of 
Tartaric acid 
Oxide of lead. .... 
And regarding this salt as composed of 1 proportional of acid and 1 of 
oxide, we obtain the number 67.0 as the representative of tartaric 
acid, for 
167 : 100 : : 112 : 67.0 
1694. Tartaric acid combines with the metallic oxides, and pro- 
duces a class of salts called tartrates, the composition of which will be 
obvious from the preceding datum. 
1695. Tartrate of ammonia forms very soluble prismatic crystals, of 
a cooling taste. The addition of tartaric acid to its aqueous solution 
produces a precipitate of a difficultly soluble bi-tartrate of ammonia. 
1696. Tartrate of Potassa is formed by saturating the excess of acid 
in tartar, by potassa. According to Mr. Richard Phillips (Remarks on 
the Pharmacopoeia,') 100 parts of tartar require 43.5 of carbonate of 
potassa. The resulting salt is soluble in less than twice its weight of 
water ; it crystallizes in four-sided prisms, and consists of 
1 proportional acid 
. . — 67. 
. . = 48. 
Tartrate of potassa . . . 
. . = 115. 
This salt is used in pharmacy as an aperient; it is the potassa, tartras 
of the Pharmacopoeia. Its taste is saline, and somewhat bitter. 
1697. Bitartrate, or Supertartrate of potassa. Tartar. This sub- 
stance exists in considerable abundance in the juice of the grape, and 
is deposited in wine casks, in the form of a crystallized incrustation, 
called argol, or crude tartar. It is purified by solution and crystalliza- 
tion, which renders it perfectly white : when in fine powder it is term- 
ed cream of tartar. 
It may also be formed by adding excess of tartaric acid to a solution 
of potassa. The mixture presently deposits crystalline grains, and fur- 
nishes a striking example of the diminution of solubility by increase of 
acid in the salt. Upon this circumstance the use of tartaric acid as a test 
for potassa depends, for soda forms an easily soluble supertartrate and 
consequently affords no precipitate. (578) 
Bi-tartrate of potassa is composed of 
Tartaric acid 
test tor potas- 
sa. 
2 proportionals of acid. . = 
134 
1 proportional of potassa = 
48 
Bi-tartrate of potassa = 
182 TARTRATES OF POTASSA, SODA, 4’C. 
This salt requires 120 parts of water at 60°, and 30 parts at 212° 
for its solution. 
When exposed to heat, tartar fuses, blackens, and is decomposed : 
and carbonate of potassa is the remaining result (569). Provided the 
tartar be free from lime, which however is seldom the case, this fur- 
nishes a good process for obtaining pure carbonate of potassa. The 
aqueous solution of tartar becomes mouldy when exposed to air, and 
the tartaric acid being entirely decomposed leaves a weak solution of 
carbonate of potassa. 
The component parts of tartar render it an excellent flux in the re- 
duction of metallic ores upon a small scale, its alcali promoting their 
fusion, and the carbonaceous matter tending to reduce the oxides. 
1698. Tartrate of Potassa and Ammonia is formed by saturating the 
excess of acid in tartar with ammonia. It effloresces and loses ammo- 
nia by exposure to air. 
1799. Tartrate of Soda forms acicular crystals soluble in their own 
weight of water. Tartaric acid, added to their solution, forms a su- 
pertartrate of soda, much more soluble than the corresponding salt of 
potassa. 
1700. Tartrate of Potassa and Soda is prepared by saturating the 
excess of acid in tartar, with carbonate of soda ; it is the soda tartari- 
zata of the Pharmacopoeia; it forms irregular prismatic crystals. It 
has long been used in pharmacy under the name of Rochelle Salt and 
Sel de Seignette. According to Vauquelin’s analysis (Fourcroy’s Con- 
naissances, vii. 240.) this salt consists of 54 tartrate of potassa -t~t46 
tartrate of soda per cent.: these numbers agree with 
Flux. 
2 
proportionals of acid . . ~ 134 
1 
potassa = 48 
1 
soda . . = 32 
214 
1701. Tartrate of Lime is nearly insoluble in cold water, but soluble 
in 600 parts of boiling water ; it is produced by adding chalk to tartar, 
as in the process for obtaining tartaric acid, where it is decomposed by 
sulphuric acid. 
1702. Tartrate of Potassa and Lime may be formed by adding lime- 
water to solution of supertartrate of potassa, till it begins to become 
turbid : in a few days acicular crystals of the above triple salt are de- 
posited, which effloresce when exposed to air. 
1703. Tartrate of Baryta is a difficultly soluble salt. 
1704. Tartrate of Strontia is thrown down on mixing the solutions of 
tartrate of potassa and nitrate of strontia. It dissolves in rather more 
than 300 parts of boiling water, and forms small crystals as the solution 
cools. 
1705. Tartrate of Magnesia is precipitated from the sulphate by tar- 
taric acid : it is soluble in excess of tartaric acid, and forms a crystalli- 
zable salt. 
1706. Tartrate of Manganese, formed by dissolving protoxide of 
manganese in tartaric acid, is a soluble salt, and therefore not produced 
by adding tartaric acid or a neutral tartrate to protomuriate or proto- 
sulphate of manganese. 
1707. Tartrate of Iron. Both the tartrates of iron are easily solu- 496 
TARTRATE OF IRON, COFFER, 8fC. 
ble, and no precipitate is formed by tartaric acid, or by tartrate of po- 
tassa, in solutions of iron. 
1708. Tartrate of Iron and Potassa. This is the Ferrum tartarisa- 
tum of the Pharmacopoeia, but it is most conveniently employed as a 
medicine in solution, which may be formed by digesting 1 part of soft 
iron filings with 4 of tartar; this mixture should be made into a thin 
paste with water, and digested for some weeks, till the acid is neutra- 
lized, fresh portions of water being occasionally added to prevent 
exsiccation. The solution of this compound, which contains the iron 
in the state of peroxide, is possessed of some curious properties, first 
pointed out by Mr. R. Phillips.—Experimental Examination of the 
London Pharmacopoeia, 98. 
1709. Tartrate of Zinc is formed by adding tartrate of potassa to 
sulphate of zinc, and appears to be a very difficultly soluble compound. 
1710. Tartrate of Tin. Tartrate of potassa occasions a white pre- 
cipitate in the protomuriate and permuriate of tin. 
1711. Tartrate of Potassa and Tin is formed by boiling the oxide in 
solution of tartar; it is very soluble, and the addition of alcalis and 
their carbonates occasion no precipitates.—Thenard, Annales de Chim. 
xxxviii. 
1712. Tartrate of Copper is produced by adding tartaric acid to sul- 
phate of copper. It forms bluish-green crystals. 
1713. Tartrate of Potassa and Copper is formed by boiling oxide of 
copper and tartar in water ; the solution yields blue crystals on evapo- 
ration ; or if boiled to dryness, furnishes one of the pigments called 
Brunswick green. 
1714. Tartrate of Lead is thrown down in the form of an insoluble 
white powder on adding tartaric acid to solution of nitrate of lead. Its 
composition has already been adverted to (1693). 
1715. Tartrate of Potassa and Lead is formed, according to The- 
nard, by boiling a mixture of tartar and oxide of lead in water.—An- 
nales de Chim., xxxviii. 
1716. Tartrate of Antimony has not been examined. 
1717. Tartrate of Antimony and Potassa. Emetic Tartar. This 
compound may be obtained by boiling protoxide of antimony, obtained 
by any of the processes formerly described (907) with pure supertar- 
trate of potassa. It is the antimonium tartarizatum of the London 
Pharmacopoeia. 
Emetic tartar may be prepared by boiling a solution of 100 parts of 
tartar with 100 parts of finely levigated glass of antimony, or of the 
protoxide described above (907) ; the ebullition should be continued 
for half an hour, and the filtered liquor evaporated to about half its 
bulk, and set aside to crystallize : octoedral and tetraedral crystals of 
the emetic salt are thus obtained ; and there is generally formed along 
with them a portion of tartrate of lime and potassa, which is deposited 
in small tufts of a radiated texture, and which may easily be separated 
when the mass is dried. 
Mr. Phillips, in his Experimental Examination of the London Phar- 
macopoeia, has stated several facts respecting the formation of this salt, 
which will be found useful to the manufacturer. 
Emetic tartar is a white salt, slightly efflorescent, soluble in about 
14 parts'of cold and 2 parts of boiling water. It is decomposed by the 
alcalis, and when heated with ammonia, a portion of protoxide of an- OXALIC ACID. 
iimony is thrown down, and a very soluble compound remains in the 
liquor. Sulphuretted hydrogen and hydrosulphuret of ammonia pro- 
duce orange-coloured precipitates in its solution. It is decomposed by 
bitter and astringent vegetable infusions, but they do not render it in- 
active as a medicine. Mr. Phillips has shown that emetic tartar con- 
sists of 100 supertartrate of potassa + 66 protoxide of antimony. If 
we consider it, with Dr. Thomson, (System, ii. 670.) as a compound of 
2 proportionals of tartaric acid, 2 of protoxide of antimony, and 1 of 
potassa ; or as containing 1 proportional of tartrate of potassa and 1 of 
subtartrate of antimony, its components will stand thus : 
Tartaric acid 
. 67 X 2 — 134 
Protoxide of antimony . 
. 66 X 2 = 112 
Potass a 
294 
1718. Tartrate of Bismuth has not been examined, but moist oxide 
of bismuth boiled with tartar forms a difficultly soluble triple salt. 
1719. Tartrate of Cobalt. Tartrate of potassa forms no precipitate 
in solutions of cobalt, but their colour is much heightened by it. 
1720. Tartrate of Uranium is a very soluble salt, not easily crystal- 
lizable. 
1721. Tartrate of Titanium appears to be a soluble compound. 
1722. Tartrate of Cerium, according to Hisinger and Berzelius, is 
formed by adding tartrate of potassa to sulphate, nitrate, or muriate of 
cerium. It is a soft tasteless powder, soluble in nitric, muriatic, and 
sulphuric acids, and in the alcalis. 
1723. Tartrate of Nickel, formed by digesting moist oxide of nickel 
in tartaric acid, is a very soluble salt; tartaric acid occasions no preci- 
pitate in the soluble salts of nickel. 
1724. Tartrate of Mercury. Tartaric acid occasions white precipi 
thtes in all the solutions of oxide of mercury not containing excess of 
acid. 
1725. Tartrate of Potassa and Mercury is formed, according to The- 
nard, by adding solution of tartar to nitrate of mercury. 
1726. Tartrate of Silver. Tartaric acid occasions no change in ni- 
trate of silver, but tartrate of potassa forms a white precipitate, which 
is probably a tartrate of silver. 
1727. Tartrate of Silver and Potassa is thrown down by adding tar- 
tar to nitrate of silver. 
1728. Tartrate of Alumina is a soluble uncrystallizable compound of 
an astringent flavour. 
ii. Oxalic Acid. 
1729. This acid is found in some fruits, and in considerable quantity 
in the juice of the Oxalis Acetosella, or wood-sorrel, and in the varieties 
of rhubarb. It is most readily procured by the action of nitric acid 
upon sugar, and has hence been termed acid of sugar. 
It may be obtained by introducing into a retort 4 ounces of nitric acid 
diluted with 2 of water and 1 ounce of white sugar ; nitric oxide gas is 
copiously evolved, and when the sugar has dissolved, about one-third of 
the acid may be distilled over: the contents of the retort are then erap- OXALATES OP VOTASSA. 
tied into a shallow vessel, and in the course of two or three days an 
abundant crop of white crystals is deposited, and, upon further evapo- 
ration of the mother-liquor, a second portion is obtained. The whole 
crystalline produce is to be re-dissolved in water, and again crystallized, 
by which the pure acid is obtained. In this way sugar yields rather 
more than half its weight of oxalic acid. 
1730. Oxalic acid thus procured is in the form of four-sided prisms, 
transparent, and of a very acid taste : they dissolve in two parts of 
water at 60°, and in their own weight at 212°. When carefully dried, 
they fall to powder, and lose more than one-third of their weight, be- 
ing composed, according to Berzelius, (Ann. de Chim. lxxxi.) of 
Real acid . . . 
... 52 
Water .... 
... 48 
100 
1731. By repeated distillation with nitric acid, oxalic acid is resolv- 
ed into carbonic acid and water; and the acid itself, and the salts con- 
taining it, as is the case with the other vegetable acids, are decompos- 
ed by heat. By distilling oxalate of lime, Dr. Thomson found the 
acid resolved into five new substances ; namely, water, carbonic acid, 
carbonic oxide, carburetted hydrogen, and charcoal; and by a very 
elaborate analysis of these gases, he determined the composition of the. 
acid as follows : 
Oxygen .... 
... 64 
Carbon .... 
Hydrogen . . . 
100 
which numbers do not quite correspond with those given by Gay-Lus- 
sac and Thenard (p. 17). 
1732. The number representing the oxalic acid, founded upon Dr. 
Wollaston’s analysis of thebmoxalate of potassa, (Phil. Trans. 1804.) 
and upon Berzelius’s analysis of the oxalate of lead, (Annales de Chi- 
mie, No. 243.) is about 37.7. According to the latter chemist, oxa- 
late of lead consists of 100 oxalic acid -{- 296.6 oxide of lead, and 
296.6 : 100 :: 112 : 37.7 
The number deduced from the mean of the best analyses of oxalate 
of lime, is 37.7; and accordingly, 38 may without material error be 
adopted as the representative number of oxalic acid, and the composi- 
tion of the oxalates will be obvious accordingly. 
1733. Oxalate of Ammonia is a very useful test for the presence of 
lime. It crystallizes in long prisms, of which 45 parts require 1000 of 
water for their solution. Added to any soluble compound of lime this 
salt produces an insoluble oxalate of lime. 
1734. Oxalate of Potassa forms flat rhomboidal crystals soluble in 3 
parts of water at 60°. It consists of 38 acid -f- 48 potassa. This salt, 
dissolved in oxalic acid, produces the hinoxalate of potassa, which crys- 
tallizes in four-sided prisms, and consists of 2 proportionals acid 38 X 
2 = 76 -j- 48 potassa. When this binoxalate is digested in dilute ni- 
tric acid, a portion of the alcali is taken up, and a salt remains, consist - OXALATE OP IRON. 
mg of 4 proportionals of oxalic acid 38 X 4 = 152 -J- 1 proportional 
potassa — 48. This is the quadroxalate of potassa, and is the salt 
which exists in the wood-sorrel. 
1735. Oxalate of Soda is sparingly soluble in water, and separates 
from its solution in small crystalline grains. 
1736. Oxalate of Lime. This compound is formed by adding oxalic 
acid or oxalate of ammonia to any solution of lime. It is insoluble in 
water, and in excess of oxalic acid, but dissolves in muriatic and nitric 
acids : hence in testing acid solutions for lime by oxalic acid, or oxa- 
late of ammonia, the excess of acid should be previously neutralized. 
This oxalate consists of 38 acid + 28 lime = 66. oxalate of lime ; or of 
42.74 
57.26 
lime 
acid 
100.00 
Vogel’s analysis gives 
43.75 lime 
56.25 acid 
100. 
1737. The Oxalates of Strontia, Baryta, and Magnesia, are very 
nearly insoluble, and with most other metallic oxalates may be formed 
by double decomposition. They consist respectively of one propor- 
tional of each of their components. 
1738. When black oxide of manganese and superoxalate of potassa 
are triturated together andmoistened, carbonic acid is evolved ; and on 
adding more water, and filtering, a red solution, containing oxalic acid, 
potassa, and deutoxide of manganese is obtained, which after a time be- 
comes colourless, and a triple salt is formed, containing the protoxide 
of manganese. 
1739. Oxalate of Iron. The protoxalate crystallizes in green 
prisms, and maybe formed either by digesting the metal, or dissolving 
the protoxide in the acid. The peroxalate is thrown down from the per- 
muriate or persulphate of iron, in the form of a difficultly soluble yel- 
low powder, which is taken up again by excess of oxalic acid : hence 
the use of this acid in removing iron-moulds which it does without in- 
juring the texture of linen. 
1740. Oxalate of Zinc is formed by adding oxalic acid to a soluble 
salt of zinc : it is a white powder, nearly insoluble. 
1741. Oxalate of Tin is formed, according to Bergman, by digesting 
the metal in the acid : the solution, slowly evaporated, gives prismatic 
•crystals. 
1742. Oxalate of Copper. Oxalic acid oxidizes and dissolves cop- 
per. When oxalic acid is added to persulphate or pernitrate of cop- 
per, a difficultly soluble peroxalate of copper is thrown down. The 
theoretical composition of this salt is 1 proportional peroxide of cop- 
per = 80. -f-2 of oxalic acid 76. = 156. 
1743. Oxalate of Copper and Ammonia. This, and several other 
triple oxalates of copper, have been described by Vogel. (Schweio- 
Annals of Philosophy, Vol. v. 30. OXALATE or MERCURY, SILVER, t%'C. 
ger’s Journal, vii.) By digesting peroxalate of copper in a solution of 
oxalate of ammonia and filtering, rhomboidal crystals were obtained on 
evaporation, which detonate when suddenly heated: when slowly 
heated they merely lose water and ammonia. From the analysis of 
this salt it evidently consists of 2 proportionals of oxalate of ammonia, 
1 peroxalate of copper, and 6 water. 
By digesting oxalate of copper in caustic ammonia, and pouring the 
solution thus obtained into a shallow basin, it deposits flat six-sided 
prisms of a blue colour, which effloresce on exposure to air. The un- 
dissolved portion of the oxalate also combines wuth ammonia, and pro- 
duces another distinct compound. Dr. Thomson has given the follow- 
ing view of the composition of these salts.—System ii., 624. 
1st. Subspecies. 2d. Subspecies. 
3d. Subspecies. 
Oxalic acid 
2 . . 
Ammonia 
2 . . 
. . . 1 
Peroxide of copper 
. . . 1 . . . 
1 . . 
Water 
. . . 6 . . . 
2 . . 
. . . 0 
1744. Oxalate of Copper and Potassa is obtained by digesting percar- 
bonate of copper in solution of binoxalate of potassa. Acicular and 
rhomboidal crystals are formed, which Vogel considers as two distinct 
salts.—Thomson’s System, ii., 620. 
1745. Oxalate of Copper and Soda. Vogel has also described (wo 
subspecies of this salt.—Schweigger’s Journal, vii.; Thomson, ii., 
621. 
1746. Oxalate of Lead is thrown down in crystalline grains on add- 
ing oxalic acid to nitrate of lead. Its composition has already been 
stated (1732). 
1747. Oxalate of Antimony has not been examined. 
1748. Oxalate of Bismuth is deposited in crystalline grains, when so- 
lution of oxalic acid is dropped into nitrate of bismuth. 
1749. Oxalate of Cobalt is an insoluble red powder, precipitated by 
oxalic acid from solutions of cobalt. 
1750. Oxalate of Uranium is a soluble compound. 
1751. Oxalate of Nickel is thrown down from the nitrate in the 
form of an insoluble green powder. 
1752. Oxalate of Mercury is precipitated from the nitrate by oxalic 
acid. It is scarcely soluble, and detonates when heated. 
1753. Oxalate of Silver is an insoluble white powder, which blackens 
by exposure to light. It is precipitated on adding oxalic acid to nitrate 
of silver, and is soluble in nitric acid. 
1754. Oxalate of Alumina is easily formed by dissolving the newly 
precipitated earth in oxalic acid : it does not crystallize, but affords on 
evaporation a gelatinous mass, which deliquesces on exposure. 
1755. The oxalic acid swallowed in large doses is an active poison, 
and fatal cases are not unfrequent in which this acid is taken by mistake 
for Epsom salt. The instant that the accident is discovered, a quan- 
tity of powdered chalk diffused in warm water should be taken, and 
vomiting excited as speedily as possible. 
Antidote for 
oxalic acid. CITRATE OF AMMONIA, 
iii. Citric Acid. 
1756. Citric acid is obtained by the following process from lemon or 
lime juice : 
Boil the expressed juice for a few minutes, and when cold, strain it 
through fine linen : then add powdered chalk as long as it produces ef- 
fervescence, heat the mixture, and strain as before : a quantity of ci- 
trate of lime remains upon the strainer, which, having been washed with 
cold water, is to be put into a mixture of sulphuric acid with 20 parts 
of water : the proportion of acid may be about equal to that of the chalk 
employed. In the course of 24 hours the citrate of lime will have suf- 
fered decomposition, and sulphate of lime is formed, which is separated 
by filtration. The filtered liquor, by careful evaporation, as directed 
for tartaric acid, furnishes crystallized citric acid. 
The preparation of this acid is carried on by a few manufacturers 
upon an extensive scale ; in different states of purity it is employed by 
the calico-printers, and used for domestic consumption. Many circum- 
stances which have not here been alluded to, are requisite to ensure 
complete success in the operation ; these have been fully described by 
Mr. Parkes, in the third volume of his Chemical Essays. The propor- 
tion of citric acid afforded by a gallon of good lemon-juice, is about 8 
ounces. 
1757. Citric acid forms crystals of a very sour taste, soluble in their 
own weight of water at 60°, and containing, according to Berzelius, 100 
real acid -f- 26.5 water, a portion of which it loses by exposure to heat. 
The analysis of this, as well as of the other vegetable acids given by 
Berzelius, differs considerably from that of Gay-Lussac and Thenard, 
in consequence, as it would appear, of the latter chemists having neg- 
lected the exclusion of water of crystallization. Berzelius gives its 
constituents as follow : 
Oxygen . . . . , 
. . . 54.831 
Hydrogen . . . . 
. . . 3.800 
Carbon 
. . . 41.369 
100.000 
1758. From the analysis of citrate of lead, the representative num- 
ber of citric acid appears to be 59.4 ; a number which closely corres- 
ponds with Berzelius’s estimate of its constitution, which is 
4 Proportionals of oxygen . . . 
. 8 X 
4 = 32 
3 hydrogen . . 
. 1 X 
3=3 
4 carbon . . . 
. 6 X 
, # 
4 = 24 
59 
The number 59. therefore, maybe adopted. 
1759. Citrate of Ammonia crystallizes with difficulty in prisms. 
1760. Citrate of Potassa is very soluble, deliquescent, and difficultly 
crystallizahle. It is much used in medicine as a mild diaphoretic, and is 
the Salt of Riverius of old pharmacy. 502 
CITRATE OF MERCURY, SILVER, <$*C. 
1761. Citrate of Soda is difficultly crystallizable in hexaedral tables, 
of a saline flavour, and soluble in somewhat less than two parts of cold 
water. 
1762. Citrate of Lime has been adverted to in the preparation of ci- 
tric acid. It is nearly tasteless, and scarcely soluble in water, but rea- 
dily soluble in solution of citric acid: when moistened it soon grows 
mouldy if exposed to air. It consists of 
1 proportional acid = 
1 lime = 
55.5 
26.5 
82. 
100 parts, therefore, of citrate of lime may be regarded as compos- 
ed of 
67 
33 
citric acid 
lime 
100 
1763. Citrate of Baryta is diffiultly soluble, and forms acicular crys- 
tals, readily soluble in excess of nitric acid. 
1764. Citrate of Strontia is crystallizable and soluble. 
1765. Citrate of Magnesia does not crystallize. 
1766. Citrate of Manganese is formed by digesting moist protoxide of 
manganese in citric acid ; it produces white arborescent crystals. 
1767. Citrate of Iron. The action of citric acid on the oxides of 
iron has not been examined. 
1768. Citrate of Zinc. Zinc dissolves in citric acid with efferves- 
cence : citric acid readily dissolves the oxide of zinc, and the solution 
deposits small crystals, scarcely soluble in water, and of an astringent 
taste. 
1769. Citrate of Tin. Neutral citrate of potassa forms no precipi- 
tate either in protomuriate or permuriate of tin. 
1770. Citrate of Copper. Citric acid forms a pale blue precipitate 
in solution of sulphate and nitrate of copper. 
1771. Citrate of Lead is thrown down in the state of a nearly inso- 
luble powder when citric acid is added to nitrate of lead. It consists 
of 
59.4 
112. 
acid 
oxide 
171.4 
1772. Citrate of Antimony is unknown. 
1773. Citrate of Bismuth is an insoluble while compound. 
1774. Citrate of Cobalt appears to be a soluble salt. 
1775. Citrate of Uranium, formed by digesting oxide of uranium in 
citric acid, is a solublf and difficultly crystallizable salt. 
1776. Citrate of Nickel is not thrown down by adding either citric 
acid or citrate of potassa to the solutions of nickel. 
1777. Citrate of Mercury. Both the protocitrate and percitrate of 
mercury are insoluble, and thrown down when citric acid or a soluble 
citrate is added to the solutions of mercury. 
1778. Citrate of Silver is an insoluble white powder, which blackens 
by exposure to light. MALIC AND GALLIC ACID. 
iv. Malic Agid. 
1779. The existence of a peculiar acid in the juice of apples, was 
shown by Scheele, in 1785. He obtained it by adding solution of ace- 
tate of lead to the expressed juice of unripe apples, by which a malate 
«f lead was formed, and afterwards decomposed by sulphuric acid. 
Vauquelin obtained it by a similar process, from the juice of the house- 
leek. The same acid exists, according to Braconnot, in the berries of 
the mountain-ash, from which it was first obtained by Mr. Donovan in 
1815, and called by him sorbic acid; the apparent differences between 
the malic and sorbic acids, are referable to the impurities of the former. 
Mr. Donovan has given the following process for its preparation. {Phil. 
Trans., 1815.) Express the juice of the ripe berries, and add solution ] 
•f acetate of lead, filter, and wash the precipitate with cold water, then 
pour boiling water upon the filter, and allow it to pass through the 
precipitate into glass jars; after some hours crystals are deposited, 
which are to be boiled with 2.3 times their Aveight of sulphuric acid, 
specific gravity 1.090. The clear liquor is to be poured off, and, 
while still hot, a stream of sulphuretted hydrogen is to be passed 
through it, to precipitate the remaining lead ; the liquid is then filtered, 
and when boiled so as to expel the sulphuretted hydrogen, is a solu* 
tion of the pure vegetable acid. 
Malic acid may also be obtained by steeping sheet-lead in the juice 
©f apples ; in a few days, crystals of malate of lead form, which may 
be collected and decomposed by the very careful addition of dilute sul- 
phuric acid. 
1780. Malic acid, when carefully prepared, is a colourless liquid, i 
very sour, and not susceptible of crystallization. It forms crystalliza- 
ble salts with many of the metallic oxides, which, however, have 
scarcely been examined with such precision as to enable us to deter- 
mine the representative number of malic acid. A detailed account of 
what is known respecting them will be found in M. Braconnot’s Me- 
moir, {Annales de Chim. et Phys., Tom. vi.) His analysis of the crys- 
tallized malate of lead gives its composition thus : 
How obtaiaea 
Properties. 
Acid ...... 
. 100. 
Oxide of lead . 
. 157.4 
If we deduce the number for the acid, from this datum, it will be 
71.1, a number which closely corresponds with the other analyses of 
the same author. 
1781. The ultimate component parts of this acid, according to Van 
quelin, are 
Hydrogen 
Carbon 
Oxygen ........ 
100.0 
v. Gallic Acid. 
1782. This acid derives its name from the gall-nut, whence it was first 
procured by Scheele. It may be obtained bv the following process: 
flow obtained GALLIC ACID. 
Digest bruised galls in boiling water, with about one-sixtli their 
weight of vellum cuttings, for some hours ; then allow the mixture to 
cool, and filter it. Add to the filtered liquor a solution of acetate ot 
lead, as long as it occasions any precipitate ; pour the whole upon a 
filter, wash the precipitate with warm water, and digest it in very di- 
lute sulphuric acid ; filter, and having saturated the clear liquor with 
chalk, evaporate to dryness. Introduce the dry mass into a retort 
placed in a sand-bath, and upon the application of heat a portion of 
water will first rise, and afterwards a crystalline sublimate of gallic 
acid. 
1783. There arc many other processes for obtaining this acid, among 
which the following deserve notice : Moisten bruised gall-nuts, and ex- 
pose them for four or five weeks, to a temperature of about 80°. A 
mouldy paste is formed, which is to be squeezed dry, and digested in 
boiling water ; it then affords a solution of gallic acid, which may be 
whitened by animal charcoal, and which, on evaporation, yields gallic 
acid, crystallized in white needles.—Braconnot, Annales de Chim. ct 
Phys., Tom. ix. 181. 
Boil an ounce of powdered galls in 16 ounces of water down to 8, 
and strain ; dissolve 2 ounces of alum in water, precipitate the alumina 
by carbonate of potassa, and, after edulcorating it, stir it into the de- 
coction ; the next day filter the mixture ; wash the precipitate with 
warm water, till this will no longer blacken sulphate of iron ; mix the 
washing with the filtered liquor, evaporate, and the gallic acid will be 
obtained in acicular crystals.—Fedler, Ure’s Dictionary. 
1784. Gallic acid, when pure, is in whitish crystals, of a sour taste* 
and which exhale a peculiar smell when heated. It dissolves in about 
10 parts of water at 60°, and in two parts at 212°. It is also soluble 
in alcohol and in ether. When repeatedly sublimed, this acid is alter- 
ed and in part decomposed. It consists, according to Berzelius (Annals 
of Philosophy, Vol. v.) of 
Properties- 
Hydrogen 
5.00 
Carbon 
Oxygen 
100.00 
And, according to the same authority, gallate of lead is composed of 
Gallic acid 
Oxide of lead 
. . . . 174 
These proportions give the number 64.3 as the representative of 
gallic acid. 
1785. The combinations of pure gallic acid with metallic bases have 
scarcely been examined, and consequently we have no accurate chemi- 
cal history of the gallates. Their solutions are all very prone to de- 
composition, and acquire a deep brown colour This acid forms no 
precipitate in solutions of potassa or of soda, but when dropped into 
lime-water, baryta water, orstrontia water, it occasions the separation 
' of a difficultly soluble gallate of those earths. It also causes a precipi- 
tate in solutions of zirconia, glucina, and yttria. 1786. When an infusion of galls is added to certain metallic solu- 
tions, it forms precipitates composed of tannin, gallic acid, and the me- 
tallic oxide, and as these are often of different colours, the infusion is 
employed as a test for such metals. The following metals in solution 
are thus thrown down, of the annexed colours . 
GALLIC ACIp. 
METAL. 
SOLUTION. 
PRECIPITATE. 
MANGANESE 
Neutral protoniuriate 
Dirty yellow 
IRON .... 
Neutral protoSulphate 
Purple 
Ditto .... 
• 
Permuriate 
Black 
ZINC .... 
Muriate 
Dirty yellow 
TIN . . . 
Acid protomuriate 
Straw-colour 
Ditto .... 
Acid permuriate 
F awn-colour 
CADMIUM . 
Muriate 
? 
COPPER . . 
Protomuriate 
Yellow brown 
Ditto .... 
Pernitrate 
Grass green 
LEAD . . . 
Nitrate 
Dingy yellow 
ANTIMONY . 
Tartrate of antimony and potassa 
Straw colour 
BISMUTH . . 
Tartrate of bismuth and potassa 
Yellow and copious 
COBALT . . 
Muriate 
0 
URANIUM . 
Sulphate 
Bluish black 
TITANIUM . 
Acid muriate 
Brown 
Ditto .... 
Neutral sulphate 
Blood red 
CERIUM . . 
Y ellowish 
TELLURIUM 
Yellow 
ARSENIC . . 
White oxide 
Little change 
Ditto .... 
Arsenic acid 
0 
MOLYBDENUM 
Brown 
NICKEL . . 
Sulphate 
Green 
MERCURY . 
Acid protonitrate 
Y ellow 
Ditto . . . . 
Acid pernitrate 
Y ellow 
Ditto .... 
Corrosive sublimate 
0 
OSMIUM . . 
Aqueous solution of oxide 
Purple becoming blue 
RHODIUM . . | 
PALLADIUM . | 
SILVER. . . 
Nitrate 
Curdy and brown after some time 
GOLD . . . 
Muriate 
Deep brown 
PLATINUM . 
Muriate 
Brownish green benzoic acid. 
The omitted metals are either not precipitated, or their action has 
not been examined. 
1787. Of these compounds, the tannogallate of iron is of the most 
importance, as forming the basis of writing ink, and of black dyes. 
When an infusion of galls is dropped into a solution of sulphate of 
iron, it produces a deep purple precipitate, which is a very long time 
in subsiding; it becomes black by exposure to air. In writing ink, this 
precipitate is retained in suspension by mucilage, and the following 
proportions appear the best which can be used. 
Finely bruised galls, 3 ounces 
Green vitriol (protosulphate of iron) 
Logwood shavings 
Gum arabic, of each 1 ounce 
Vinegar, 1 quart. 
Put these ingredients into a bottle, and agitate them occasionally 
during twelve or fourteen days ; then allow the coarser parts to settle, 
and pour off the ink for use. 
The tendency of ink to become mouldy is much diminished by keep- 
ing a fewr cloves in the ink-bottle, or by dissolving in each pint of the 
ink about three grains of corrosive sublimate. 
The colour of common writing-ink is apt to fade, in consequence of 
the decomposition of its vegetable matter; and when thus illegible, it 
may often be restored by washing the writing with vinegar, and subse- 
quently writh infusion of galls. Acids also destroy its colouring matter, 
and those inks which resist their action, contain some other colouring 
principle, usually finely powdered charcoal. Common writing ink is, 
for this reason, much improved by dissolving in the quantity above- 
mentioned about an ounce of Indian ink which is lamp-black made 
into a cake with isinglass. 
In dyeing black, the stuff is first impregnated with a solution of the 
gall-nut, and afterwards the colour is brought out by the application of 
sulphate, or acetate of iron (1611.) 
Upon these subjects much valuable information will be found in 
Lewis’s Philosophical Commerce of the Arts, and in Aikin’s Dictionary. 
1788. In the Philos. Trans, for 1817, I have described the proper- 
ties of a species of galls from China, which furnish very pure gallic 
acid, and which, could they be abundantly obtained, would certainly 
prove- a valuable substitute for common galls, in many of the processes 
in which they are employed. 
vi. Benzoic Acid. 
1789. Benzoic acid maybe obtained by sublimation fro 1n benzoin, 
which is a resinous exudation from the Styrax benzoe of Sumatra ; it 
also exists in the Balsam of Peru and of Tolu. If these substances be 
heated in a crucible, with a cone of paper attached to its mouth, the 
acid condenses in it in fine acicular crystals, which were formerly call- 
ed flowers of benzoin. A good process for procuring this acid is that 
recommended by Mr. Hatchett, which consists in digesting benzoin in 
sulphuric acid, when it affords a copious sublimate of pure benzoic 
acid. (Additional Experiments on Tannin, Phil. Trans., 1808.) It 
may also be obtained by boiling a pound and a half of powdered ben- 
zoin writh 4 ounces of quicklime, in G or 8 quarts of water. When 
How obtained BENZOATES. 
507 
cold the clear liquor is decanted, and the residuum again boiled in half 
the former quantity of water. The liquors thus obtained are boiled 
down to half their bulk, filtered, and mixed with muriatic acid, as long 
ns it occasions a precipitate, from which the liquor is poured off, and 
when dry it is put into an earthen vessel, placed in a sand heat, and 
sublimed into paper cones. 
In the tenth volume of Nicholsons’s Journal I have detailed several 
experiments on benzoin, and have shown the relative quantity of acid 
afforded by the several processes which have been recommended for 
obtaining it. 
1790. Benzoic acid, when it has been thus sublimed, is in the fornv 
<ff soft feathery crystals, of an acrid and slightly sour taste, soluble in 
about 30 parts of boiling water, and very sparingly soluble in cold wa- 
ter. It is much more soluble in alcohol, and this solution easily fur- 
nishes it in prismatic crystals. 
1791. Berzelius’ analysis gives the following as the components of 
this acid, and of the benzoate of lead: 
Characters. 
Hydrogen 
5.16 
Carbon 
74.41 
Oxygen ........ 
20.43 
100.00 
Benzoic acid 
Oxide of lead 
94 < J 
Whence it appears that the representative number of benzoic acid is 
119. 
1792. Benzoate of Ammonia forms deliquescent plumose crystals, 
very soluble in water. Berzelius recommends this salt as a precipi- 
tant of iron, which it throws down of an orange colour. 
1793. Benzoate of Potassa is a very soluble deliquescent salt ; if it 
be digested with benzoic acid, a bibenzoate of potassa results, which, ac- 
cording to Bucholz (Annales de Chimie, Ixxxiv.) forms acicular and la- 
mellar crystals, requiring ten parts of water for their solution. 
1794. Benzoate of Soda forms efflorescent crystals, very soluble in 
water. 
1795. Benzoate of Lime forms acicular crystals, sparingly soluble in 
cold water. Vauquelin found this salt in the urine of the cow. Ben- 
zoate of ammonia forms a copious white precipitate when added to mu- 
riate of lime, which is soluble in hot water. 
1796. Benzoate of Baryta is soluble and crystallizable. 
1797. Benzoate of Strontia is also a soluble salt. 
1798. Benzoate of Magnesia forms soluble plumose crystals. 
1799. Benzoate of Manganese forms beautiful prismatic crystals. 
1800. Benzoate of Iron. Benzoate of ammonia forms an insoluble 
perbenzoate when added to solutions of peroxide of iron, of a yellow 
colour : in the protosalts of iron it also forms a white precipitate. 
1801. Benzoate of Zinc forms soluble acicular crystals when there 
is excess of acid : the neutral benzoate is insoluble. 
1802. Benzoate of Tin is insoluble. 
1803. Benzoate of Copper is a fine blue insoluble compound. 
1804. Benzoate of Lead is insoluble except there be excels of acid £ 
it then forms nacreous crvstals, 508 
KINIC ACID. 
1805. Benzoate of Bismuth forms white acicular crystals, permanent 
in the air, soluble in water, and sparingly soluble in alcohol. (Tromms- 
dorf, Ann. de Chirn., xi.) When benzoate of ammonia is added to acid 
nitrate of bismuth, it forms an insoluble white precipitate ; Tromms- 
dorf’s salt therefore is probably a bibenzoate. 
1806. Benzoate of Cobalt. Benzoate of ammonia forms no precipi- 
tate in solutions of cobalt. 
1807. Benzoate of Uranium is a difficultly soluble straw-coloured 
compound, when formed by adding benzoate of ammonia to nitrate of 
uranium. 
1808. Benzoate of Nickel. Solutions of nickel are only rendered 
slightly turbid by benzoate of ammonia, benzoate of nickel is proba- 
bly therefore a soluble salt. 
1809. Benzoate of Mercury. Benzoic acid forms white precipitates 
in the solutions of mercury. 
1810. Benzoate of Silver, obtained by digesting moist oxide of silver 
in benzoic acid forms acicular crystals ; but benzoate of ammonia forms 
an abundant insoluble precipitate in solution of nitrate of silver. 
1811. Benzoate of Alumina forms arborescent crystals. 
Besides the vegetable acids which have now been described, there 
are a few others of considerably inferior interest and importance ; 
namely, the 
1812. Moroxylic acid, discovered by Klaproth, in the bark of the 
morns alba, or white mulberry (Nicholson’s Journal, vii.) An exuda- 
tion was observed upon this bark, which proved to be a compound of 
a peculiar acid and lime, or a moroxylate of lime; its solution was de- 
composed by acetate of lead, and the moroxylate of lead thus obtained 
decomposed by dilute sulphuric acid, furnished a solution of moroxylic 
acid, which gave acicular crystals on evaporation. This acid has the 
taste of succinic acid; it is soluble in water and alcohol, and does not, 
like some of its salts, form precipitates in metallic solutions. The 
quantity of this acid examined by Klaproth, was so small as to leave' 
some doubt respecting its distinct nature. 
1813. Boletic akid was obtained by Braconnot from the boletuspseudo- 
ignarius (Ann. de Chim. Tom. Ixxx.) by cautiously evaporating its 
expressed juice to the thickness of syrup, digesting it in alcohol, dissolv- 
ing the residue in water, and adding nitrate of lead to the aqueous so- 
lution ; the precipitate washed and diffused through water, was decom- 
posed by sulphuretted hydrogen; the liquor was then filtered and 
evaporated till it formed crystals, which were purified by solution in 
alcohol and evaporation. These crystals are boletic acid ; they are 
prismatic, and require 180 parts of water at 68°, and 45 of alcohol foi: 
their solution, which reddens blues and precipitates nitrate of lead, 
and the salts containing the peroxide, but not those of the protoxide of 
iron. This acid sublimes with little alteration, when heated. Bracon- 
not has examined the boletates of ammonia, potassa, lime, and baryta, 
but his researches have not as yet been confirmed by any other chemist. 
—Thomson’s Syst. 6th edit. ii. 157. 
1814. Fungic acid was procured by the same chemist from the 
boletus juglandis, and some other fungi; it is deliquescent and uncrys- 
tallizable.—Jbmales de Chimie, lxxxvii. 
1815. Kinic acid was discovered by Vauquelin, in Cinchona. When a strong cold infusion of this bark is set aside, crystals of kinaie of lime 
are sparingly deposited by it, which may be decomposed by oxalic acid. 
The kinic acid is crystallizable, sour, and bitter : the kinates are for 
the most part soluble salts ; it is chiefly distinguished by forming no 
precipitate in solutions of lead and silver.—Annales de Chimie, lix. 
1816. In the astringent root of the Krameria triandra, M. Peschier 
has announced the existence of what he considers as a distinct substance, 
which he calls krameric acid.—Journal de Pharmacie, vi. 
1817. M. Braconnot has given the term Ellagic acid (from the word 
galle reversed) to an acid body which he has detected, along with gallic 
acid, in infusion of galls, but its characters have been but imperfectly 
ascertained. 
1818. Zumic acid was discovered by the same chemist in vegetable 
substances, which have undergone acetous ferraentatioh—Thomson’s 
Syst. Vol. ii. p. 189. 
PARTS OF PLANTS. 
Section XVIII. Of the Parts of Plants. 
1819. In the preceding Sections the principal proximate components 
of vegetables have been described, and the composition of some of 
their detached parts has been adverted to ; such of these as have not 
been previously noticed and as have been examined with any degree of 
precision, remain to be described in this Section under the heads of 
Roots. 
Barks. 
Woods. 
Leaves. 
Flowers. 
Seeds. 
Fruits. 
Bulbs. 
Lichen?. 
F ungi. 
i. Roots. 
1820. a. Ipecacuanha. This root is the produce of the Callkocca 
Ipecacuanha (Linnjean Trans, vi.) It has been examined by MM, 
Pelletier and Majendie, and an account of their researches is publish- 
ed by M. Robiquet, in the Annales de Chimie et Phys. iv. 172. 100 
parts of this root, deprived of the woody fibre which traverses its 
centre afforded 
Fatty matter 
Emetine 
Gum 
16 
Starch 
Woody fibre 
A trace of wax .... 
Loss 
100 
The means of separating the emetic principle have already fieen 
described (1595). ROOTS. 
1821. b. Valerian, the root of the Valeriana officinalis, has been 
examined by Trommsdorf (Annales de Chirnie, lxx.) The recent root 
loses about three-fourths its weight in drying. It affords, when distill- 
ed with water, an aromatic volatile oil; it also contains starch, gum, 
resin, and extractive. 
1822. c. Turmeric is the root of the Curcuma longa, a plant culti- 
vated in the East Indies, and used as a condiment, especially in Curry 
powder. Digested in water or alcohol, it furnishes a large proportion 
of yellow colouring matter, which would be very useful to the dyer, 
could it be rendered permanent. Most of the acids render it paler, 
and the alcalis change it to a deep brick-red ; hence its use as a test 
of the presence of alcaline matter. It is also reddened by boracic acid, 
and by muriatic acid gas. 
1823. d. Madder is the root of the Rubia Tinctorum, and is an arti- 
cle of great importance in dyeing ; it grows wild in most parts of the 
south of Europe, and is largely cultivated in some parts of Holland 
and the Levant; its red colour is apt to be injured by drying, a process 
requiring much caution. Good madder has a strong and peculiar smell ; 
it exhibits, when cut, a cortical and a woody part of a red colour, in- 
termixed in the former with yellow spots. The red portion is most 
soluble.—Aikin’s Dictionary. Art. Dyeing. Berthollet, Elem. de 
Teinture, ii. 
1824. e. Rhubarb is the root of the Rheum palmatum, largely culti- 
vated in the northern parts of China ; its colour is brown, with streaks 
of red and white. The following are the component parts, separable 
from the finest kinds of Turkey rhubarb.—Brande, Quarterly Journal 
of Science and the Arts, x. 291. 
Water 
Gum 
Resin 
Extract, tan, and gallic acid. . 
. 26.0 
Phosphate of lime . . . . 
. 2.0 
Mai ate of lime 
Woody fibre 
100.0 
1825. Liquorice, the root of the Glycyrrhiza glabra, has been exam- 
ined by M. Robiquet, who found in it the following substances.—An* 
nales de Chimie, lxx. 
i. Starch. 
ii. Gluten. 
iii. Liquorice sugar. 
iv. Phosphate and malate of lime and magnesia. 
v. An acrid oil. 
vi. A crystallizable substance resembling asparagin. 
vii. Woody fibre. 
The sugar is soluble in water and in alcohol, but not convertible into 
alcohol bv fermentation ; nor into oxalic acid by the action of nitric 
acid. BARKS. 
1826. Jalap, the root of the Convolvulus Jalappa, is employed in me- 
dicine as a cathartic. It is imported from South America. It has not 
been submitted to any accurate chemical analysis, but its activity is ge- 
nerally regarded as chiefly resident in its resin. The finest and dens- 
est jalap affords about 12 per cent, of resin, when digested in alcohol; 
water takes up about 30 or 35 per cent, of the remainder, and the re- 
sidue appears to be inert woody fibre. 
1827. Gentian is the root of the Gentiana lutea ; according to Mr. 
Henry (Annals of Philosophy, xvi. 89,) it contains the following sub- 
stances : 
i. A substance resembling bird-lime. 
ii. A resin combined with an oil, which gives to gentian its'pecu- 
liar odour. 
iii. A bitter extractive principle. 
iv. Gum and colouring matter. 
v. Phosphate of lime ? 
1828. a. Cinchona. The varieties of Peruvian bark have been ex- 
amined by MM. Pelletier and Caventou. In the cinchona lancifolia, or 
pale bark, they found the following constituent parts : 
ii. Barks. 
Cinchona la*, 
cifolia, pale. 
i. Cinchonine, combined with kinic acid. 
ii. Green fatty matter 
iii. Red and yellow colouring matter. 
iv. Tannin. 
v. Kinate of lime. 
vi. Gum. 
vii. Starch. 
viii. Lignin. 
1829. Cinchonine, according to the above chemists, is a salifiable 
base, forming white acicular crystals, and requiring 7000 parts of wa- 
ter for solution ; dissolved in alcohol it has a bitter taste. It is difficult- 
ly soluble in the fixed and volatile oils and in ether. 
1830. Sulphate of Cinchonine is easily crystallizable, and moderately 
soluble ; it consists of 
Cinchonine . . . „ . 
• • • 
. 100 
Sulphuric aciil. . . . 
1831. Muriate of Cinchonine is much more soluble than the sulphate, 
and contains 
Cinchonine 
Muriatic acid .... 
. . . . 7.9 
1832. Nitrate of Cinchonine appears to be uncrystallizable. Gallic, 
oxalic, and tartaric acids form difficultly soluble salts with cinchonine ; 
the precipitate occasioned by dropping tincture of galls into infusion of 
pale bark is a gallate of Cinchonine. 
1833. In the yellow bark (cinchona cordifolia) MM, Pelletier and 1 
Cordii'olia.ye';- 
low. 512 
WOODS. 
Caventou discovered a salifiable base, which they term Quinine, the 
sulphate of which is composed of 
Quinine 
Sulphuric acid 
10.9 
1834. Acetate of Quinine forms bundles of flat acicular crystals, 
while the corresponding salt of cinchonine crystallizes in small tables. 
The gallate, oxalate, and tartrate of quinine, are nearly insoluble, but 
quinine is very soluble in sulphuric ether. 
1835. In the red bark (cinchona oblongifolia) the two salifiable bases 
above described are found united.—Quarterly Journal of Science and 
the Arts, x. 388. 
1836. b. Cascarilla, the bark of the Croton Eleutheria contains, ac- 
cording to Trommsdorff—Annalesde Chimie, xxii 
©blongfifolia, 
red. 
Mucilage and bitter principle 
Parts. 
864 
Resin . 
688 
Volatile oil 
72 
Water 
48 
Woody fibre ........ 
3024 
4696 
1837. c. The bark of the horse chestnut (JEsculus hippoeastanum,) 
has been partially examined by M. Henry (Annales de Chimie, Ixxvii ) 
It appears to contain scarcely any resin ; water and diluted alcohol 
dissolve nearly the whole of its soluble contents, which are chiefly 
extractive and mucilage. Tincture of galls does not render its infusion 
turbid, it does not therefore probably contain the peculiar substances 
discovered in Peruvian bark. 
iii. Woods. 
1838. a. Brazil Wood is the produce of the Ccesalpina crista, grow- 
ing in Brazil, in the Isle of France, Japan, and other countries : the 
wood is hard and heavy, and though pale when recent, it acquires a 
deep red colour by exposure. Digested in water it affords a fine red 
infusion, of a sweetish flavour ; the residue, which appears nearly 
black, imparts much of its colour to alcaline liquors. With alcohol it 
gives a deep red tincture : alcalis and soap convert its red colour to a 
fine purple, hence paper tinged with Brazil wood is sometimes used as 
a test for alcalis ; acids render it yellow ; alum produces a fine crimson 
lake with infusion of Brazil wood ; muriate of tin forms with it a crim- 
son precipitate, bordering on purple ; the salts of iron give a dingy 
purple colour. Sulphuretted hydrogen destroys the colour of infusion 
of brazil wood, but it re-appears on expelling the gas.—Chevreud, 
Annales de Chimie, lxvi. 
1839. b. Red Sandal, or Saunders, is the wood of the Pterocarpus san- 
lalinus, a native of several parts of India. Its deep red colouring mat- 
ter is insoluble in water, but readily soluble in alcohol; it is chiefly 
employed for colouring a few pharmaceutical tinctures. The insolu- 
bility of its colouring principle in water furnishes a ready mode of dis- 
tinguishing between it and brazil wood ; and its solubility in alcohol 
renders it probable that it is of a resinous nature. 513 
1840. c. Logwood, the produce of the Hcematoxylon campechianum, 
has already been noticed as containing a peculiar colouring principle 
(1586). It imparts a fine purple or crimson colour to pure water, but 
its tint is altered by the slightest metallic impregnation ; alcalis deepen 
it, and acids render it paler ; alum forms with it a violet-coloured lake ; 
sulphate of iron renders the infusion of logwood deep purple, or near- 
ly black ; sulphate of copper and acetate of lead throw down brown 
and purple precipitates ; and muriate of tin precipitates the whole of 
the colouring matter, in the form of a purple compound. The colours 
which logwood produces are for the most part very perishable.—Ban- 
croft, on Permanent Colours, ii. 338. Chevreul, Annales de Chimie, 
lxvi. 254. 
FLOWERS. 
iv. Leaves. 
1841. a. Senna. According to Lagrange (Annales de Chimie, xxvi.) 
the leaves of the Cassia sennit are characterized by containing a pecu- 
liar extractive principle, which, by long boiling, passes into a resinous 
substance, in consequence of absorbing oxygen; they also contain a 
resin which resists the action of water, and is soluble in alcohol; the 
whole of the soluble matter amounts to about one-third the weight of 
the senna. In the London Medical Repository, Vol. xv., 169, the ef- 
fects of the various re-agents on infusion of senna are detailed by Mr. 
Batley. 
1842. b. Nightshade. The leaves of the Atropa Belladonna contain, 
according to Vauquelin (Annales de Chimie, lxxii), 
i. Vegetable albumen. 
ii. A bitter narcotic principle. 
iii. Nitrate, muriate, sulphate, binoxalate, and acetate of po- 
tassa. 
Dr. Brandes has announced the existence of a new vegetable alcali 
in this plant, which he calls atropia. It forms brilliant acicular crys- 
tals, tasteless, and difficulty soluble in water and alcohol. It affords dis- 
tinct salts with the acids ; the Sidphate of Atropia consists of 
Sulphuric acid . 
.... 36.52 
Atropia 
.... 38.93 
Water 
.... 24.55 
100.00 
1843. c. Hyoscyamus Niger, or Henbane. In the leaves of this plant 
Dr. Brandes has also ascertained the presence of a peculiar, and high- 
ly poisonous salifiable base which he calls hyoscyama. With the acids 
it forms characteristic salts ; it crystallizes in long prisms. 
v. Flowers. 
1844. The colouring matter of most flowers is extremely fugitive, 
and is generally much changed by mere exsiccation. They usually 
communicate their colour to water ; the infusion of blue flowers is ge- 
nerally reddened by acids, and changed to green or yellow by alcalis ; 
that of yellow flowers is made paler by acids, and alcalis render it 
brown; the red infusion of many flowers is exalted in tint by acids, 
and changed to purple, and in some instances, to green by alcalis. 
It is probable that one and the same principle gives colour to seve- 514 
SEEDS. 
ral cf the blue and red flowers, but that the presence of acid in the 
latter produces the red ; the petals of the red rose, triturated with a 
little carbonate of lime and water, give a blue liquor ; alcalis render it 
green, and acids restore the red. 
1845. A colouring matter, analogous to that of the violet, exists in 
the petals of red clover, in the red tips of those of the common daisy, 
of the blue hyacinth, the holly-hock, lavender, in the inner leaves of 
of the artichoke, and in numerous other flowers ; reddened by an acid, 
it colours the skin of several plums, and the petals of the scarlet gera- 
nium and pomegranate. Some flowers which are red, become blue by 
merely bruising them ; this is also the case with the colouring matter 
of red cabbage leaves, and of the rind of the long radish. Mr. Smith- 
son has suggested that the reddening acid is in these cases the carbon- 
ic, Avhich escapes on the rupture of the vessels which enclose it. . 
1846. The petals of the common corn-poppy, rubbed upon paper, give, 
a purple stain, little altered by ammonia or carbonate of soda, but made 
green by caustic potassa. The infusion of poppy-petals in very dilute 
muriatic acid, is florid red ; chalk added, renders it of the colour of 
port wine ; carbonate of soda in excess gives the same colour, but ex- 
cess of potassa changes it to green and yellow. The expressed juice 
of the black mulberry possesses nearly the same properties.—Smith- 
son, Phil. Trans. 1818, 110. 
1847. The flowers of the carthamus tinctorius, or safflower, culti- 
vated chiefly in Spain and the IJfevant, contain a yellow colouring mat- 
ter, easily soluble in water, and a red, soluble in alcohol and weak al- 
ealine liquors ; the latter only is employed. Rouge is the red colour- 
ing matter of the carthamus, obtained by digesting the washed flowers 
in solution of carbonate of soda, and adding lemon juice, which throws 
it down in the form of a fine powder, which is dried and mixed with a 
portion of powdered talc ; carthamus is also used for dyeing silk. 
The details of the analysis of carthamus will be found in the Essays of 
Dufour and Marchais.—Annales de Chimie, xlviii. 
vi. Seeds. 
1848/ Starch is an essential component of the greater number of 
seeds, and it is generally united in them with a variable portion of glu- 
ten, and often of fixed and of volatile oil. The component parts of 
wheat-flour, and of several esculent grains, have already been stated 
(1581,) and a variety of curious details respecting them will be found 
in Einhoff’s Papers, in Gehlen’s Journal. 
Sir H. Davy has also examined a number of seeds, with a view to de- 
termine their relative nutritive powers ; the results of his experiments 
are seen in the table at the end of this section. 
1849. Almonds, the seed of the amygdalus communis, consist of an 
albuminous substance and oil ; the latter may be obtained by expres- 
sion, five pounds yielding about one pound of cold drawn oil, and about 
a pound and a half when aided by heat. The bitter almond affords by 
pressure an oil analogous to that from the former ; but if the express- 
ed cake be distilled with water, a portion of volatile oil, eminently pois- 
onous, and smelling strongly of the almond, is obtained ; this oil is used 
ns a flavouring material by confectioners, and by the manufacturers of 
noyau. In the Philosophical Transactions for 1811, Mr. Brodie has SEEDS. 
detailed a variety of experiments illustrative of its action as a poison, 
in which, as well as from its odour, it appears identical nearly with hy- 
drocyanic acid. 
1850. Lentiles, the seed of the ervum lens, contain, according to Ein- 
hoff, in 3840 parts, 
Woody fibre 
Albumen - - - 
- - - 720 
- - - 44 
Earthy phosphates 
Extractive, soluble in alcohol - - - 
- - -' 22 
- - - 120 
Gum - -- -- 
- - - 230 
Starch 
- - - 1260 
Gluten 
- - - 1433 
Loss 
3840 
1851. The seeds of the white lupine (lupinus albus) contain, accord- 
ing to Fourcroy and Vauquelin (Ann. du Museum, No. xxxvi.), gluten, 
and a green acrid oil, with a considerable portion of phospate of lime 
and magnesia, but no starch or sugar. 
1852. Coffee, the seed of the Coffea Arabica, has been examined both 
in its raW and roasted state. From 64 parts of raw coffee, Cadet (Atm. 
de Chimie, lviii.) obtained 
Gum - . - - 
8. 
Resin and bitter extract 
2.0 
Gallic acid ---------- 
3.5 
Insoluble matter 
43.5 
Loss, including a trace of albumen 
7.0 
64. 
Hermann has given the following comparative analysis of coffee from 
the Levant and from Martinique (Crell’s Annals, ii.), the results of 
which differ much from those of Cadet: 
Levant. 
Martinique: 
Resin 
Extractive 
Gum 
Fibrous matter . . , 
. . 1335 . . 
. . . , 1386 
Loss 
. . . . 12 
1920 
1920 
When coffee is roasted it undergoes a peculiar change of composi- 
tion, attended by the formation of tan, and a volatile, fragrant, and aro- 
matic principle ; but in this state it has not been examined with any 
precision. 
1853. Pepper. The 'seed of the piper nigrum has not been satisfac- 
torily analyzed : it imparts its acrimony to alcohol and to water ; it 
contains a species of volatile oij, with starch and extractive matter,— 
Nicholson’s Journal, ii. 1854. Mustard. The seed of the sinapis nigra derives its acrimo- 
ny from a volatile oil; it also contains a tasteless fixed oil, albumen, 
gum, and traces of sulphur find earthy salts. 
1855. The seeds of the lycopodium clavatum, or common club moss, 
have been analyzed by Bucholz. (Gehlen’s Journal, vi.) From 
1000 parts he obtained 
BRUITS. 
Fixed oil 
. . . . 60 
Sugar 
. . . . 30 
Mucilage 
. . . . 15 
Insoluble residue .... 
. . . . 895 
1000 
This seed has the appearance of a fine yellow powder, which defla- 
grates when projected into the flame of a candle ; it is used in theatres 
to imitate lightning; and the German apothecaries employ it to pre- 
vent the adhesion of pills. 
1856. Annotta is the produce of the bixa orellana, a tree cultivated 
in various parts of America. When the capsules are ripe, the seeds 
are bruised and steeped for several weeks in water, until converted 
into a pulp, which is allowed to putrefy, and being diffused through a 
fresh portion of water, is heated till a scum rises, which is successive- 
ly removed as it forms, and being carefully dried, is made up into cakes, 
and wrapped in palm leaves for exportation. 
Annotta is soluble in water and alcohol; the solutions have a disa- 
greeable smell, and are of an orange colour ; alcalis render it more so- 
luble and increase its colour : alum and the acids separate it from its 
solutions in the form of a yellow sediment: it is used for dyeing silk 
and colouring cheese. 
vii. Fruits. 
1857. The acid matter contained in fruits is either the tartaric oxa- 
lic, citric, or malic ; or a mixture of two or more of them ; but the 
nature and proportion of the acid varies at different periods of their 
growth ; gluten and starch are found in some fruits, and a gelatinizing 
substance, which has sometimes been regarded as identical with animal 
jelly, but which is probably a compound of gum and one or more vege- 
table acids. 
1858. Most of our common fruits also contain sugar, and it exists in 
all those the juice of which is susceptible of vinous fermentation. In 
some fruits the quantity of sugar is increased by mashing and exposure 
to air ; this is remarkably the case with some of the rough-flavoured 
apples used for cider, the pulp of which becomes brown, and at the 
same time sweet by a few hours’ exposure. 
1859. The colouring matter of fruits seems in most cases to bear a 
strong resemblance to that of flowers. The red juice of the mul- 
berry was found to exhibit the same characters as the colouring prin- 
ciple of the wild poppy ; carbonated alcalis render it blue, but caus- 
tic potasSa changes it to green and yellow : the juice of red currants, 
cherries, elder berries, and privet berries, and the skin of the buck- 
thorn berry, appear to contain a similar colouring principle. 
1860. berries of the buckthorn furnish a juice, which, 
Their con- 
tents. 517 
when inspissated, is known under the name of sap green. It is soluble 
in water, and rendered yellow by carbonate of soda and caustic potas- 
sa; the acids redden it, and carbonate of lime restores it to green, 
which is therefore probably the proper colour of the substance. 
(Smithson, Phil. Trans., 1818, p. 116). 
1861. The fruit of the wild cucumber (cucumis elaterium) furnishes 
a very acrid juice, which deposits the powerful cathartic known under 
the name of elaterium. This substance occurs in commerce in thin 
cakes of a greenish colour and bitter taste; it derives its cathartic 
power from a small portion of a very active principle, which Dr. 
Paris has called Elatin: (Pharmacologia, 223, 3d. Edit.) from 10 grains 
of elaterium he obtained 
PULBS. 
W ater 
- - - 0.4 
Extractive 
- - - 2.6 
Fecula 
2.8 
Gluten - 
- - - 0.5 
Woody matter - - 
- - - 2.5 
Elatin - > 
10. 
Bitter principle - - $ 
1862. The potatoe, which is the bulbous root of the solanum tubero- 
sum, has been examined by Dr. Pearson and by M. Einholf; from 100 
parts, the latter chemist obtained 
viii. Bulbs. 
Starchy matter 
- - - 22 
Albumen and mucilage - - 
- - - 5.4 
27.4 
The average quantity of nutritive matter contained in the potatoe, 
amounts to about one-fourth its weight. When potatoes become sweet 
by exposure to frost, a portion of the mucilage passes into the state of 
sugar, for Einhoff found the quantity of starch undiminished. 
1863. Garlic, or the bulbous root of the allium sativum, has been 
examined by Cadet. (Ann. de Chim., lix.) It loses by drying about 
two-thirds of its weight; its juice is viscid, and very slightly sour ; it 
yields coagulated albumen when heated, and when distilled with water 
furnishes an acrid oil having a strong odour of garlic. 
1864. The bulb of the Allium Cepa, or Onion, has been analyzed 
by Fourcroy and Vauquelin (Ann. de Chimie, lxv.). The juice of this 
root, when exposed to a temperature of about 70°, forms a quantity of 
vinegar, and deposits a sediment having the characters of gluten com- 
bined with oil and sulphur. In the acetous solution is contained a sub- 
stance having the properties of manna, and which is probably a product 
of the fermentation, for none could be detected in the recent juice. 
1865. Squill, the bulbous root of the Scilla maritima contains, ac- 
cording to Vogel, (Annales de Chun, lxxxiv.) a peculiar bitter principle, 
which he terms Scillitin, combined with gum, and a considerable por- 
tion of tannin. FUNGI. 
ix. Lichens. 
1866. There are several lichens which abound in colouring matter ; 
of these the most remarkable is the Lichen rocella, which grows in the 
South of France and in the Canary Islands, and which affords the beau- 
tiful but perishable blue called litmus, archil, or turnsole. The moss 
is dried, powdered, mixed with pearlash and urine, and allowed to fer- 
ment, during which it becomes red, and then blue ; in this state it is 
mixed with carbonate of potassa and chalk, and dried. It is used for 
dyeing silk and ribands, and by the chemist is a most delicate test of 
acids, which it indicates by passing from blue to red ; the blue colour 
is restored by alcalis, which do not render it green. Cudbear appears 
to be a similar preparation of the lichen tartareus.—Bancroft on Co- 
lours, i., 300. 
Mr. Smithson has thrown some doubt upon the use of alcalis in the 
precipitation of litmus, for he found its tincture produce no change on 
solutions of muriate of lime, nitrate of lead, muriate of platinum and 
oxalate of potassa; he at the same time suggests the idea of its being 
a compound of a vegetable principle with potassa.—Phil. Trans., 1818> 
p. 112. 
1867. The Lichen Islandicus, or Iceland Moss, has been subjected to 
analysis by Berzelius. (Annales de Chimie, xc.) He obtained from it 
the following substances : 
Syrup 
Bi-tartrate of potassa 
Tartrate of lime 
- - - - 3.6 
:::j ... 
Phosphate of lime 
Bitter principle - - 
:::» « 
Wax 
1.6 
Gum - - - 
- - - - 3.7 
Colouring extract 
7.0 
Starch 
- - - 44.6 
Insoluble starchy matter - - - ■ 
- - - - 36.6 
102.0 
x. Fungi or Mushrooms. 
1868. M. Braconnot, who has lately examined many fungi with mi- 
nute attention, has given the name fungin to the insoluble spongy por- 
tion which they contain, and which in many respects resembles lignin : 
he has also detected in them two peculiar acids, which he terms fungic 
acid (1814) and boletic acid (1813) ; the method of extracting which 
has been above described. A peculiar fatty matter, or adipocer, has 
been found by Vauquelin and Braconnot, in several of the fungi; an 
albuminous substance, and salts, some of which are boletates and fun- 
gates, have also been detected in them, but the analyses are too abstruse, 
and the results too complicated, to be regarded as perfectly satisfactory. 
—Annales de Chirnie, lxxix., lxxxv., <^c. 
1869. The following table, drawn up by Sir H. Davy, exhibits the 
relative proportions of soluble and of nutritive matter contained in 1000 FERMENTATION. 
parts of the different vegetable substances enumerated in the first co 
iutnn (Agricultural Chemistry, 4to., p. 131.): 
VEGETABLES 
or 
VEGETABLE SUBSTANCE. 
Whole 
quantity of 
Soluble or 
N utrilive 
Matter 
Mucilage 
or 
Starch. 
Saccharine 
Matter or 
Sugar. 
Gluten 
or 
Albumen. 
Extract, or 
matter ren- 
dered inso- 
luble during 
evaporation. 
Middlesex Wheat, average crop 
955 
765 
190 
Spring Wheat 
940 
700 
240 
Mildewed Wheat of 1&06 «... 
210 
178 
32 
Blighted Wheat of 1804 .... 
650 
520 
130 
Thick-skinned Sicilian Wheat of 1810 
955 
725 
230 
Thin-skinned Sicilian Wheat of 1810 
961 
722 
239 
Wheat from Poland 
960 
750 
200 
North American Wheat 
955 
730 
225 
Norfolk Bariev 
920 
790 
70 
60 
Oats from Scotland 
743 
641 
15 
87 
Rye from Yorkshire 
792 
645 
38 
109 
Common Bean 
570 
426 
103 
41 
Dry Peas 
574 
501 
22 
35 
16 
Potatoes 
f from 260 
i from 200 
C from 20 
r from 40 
) to 200 
\ to 155 
t to 15 
•> to 30 
Linseed Cake 
151 
123 
11 
17 
Red Beet 
148 
14 
121 
14 
White Beet 
136 
13 
119 
4 
Parsnip 
99 
9 
90 
Carrots 
98 
3 
95 
— 
Common Turnips 
42 
7 
34 
1 
Swedish Turnips 
64 
9 
51 
2 
2 
Cabbage 
73 
41 
24 
8 
Broad-leaved Clover 
39 
31 
3 
2 
3 
Long-rooted Clover * 
39 
30 
4 
3 
2 
White Clover 
32 
29 
1 
3 
5 
Sainfoin . 
39 
28 
2 
3 
6 
Lucerne 
23 
18 
1 
4 
Meadow Fox-tail Grass 
33 
24 
3 
6 
Perennial Rye Grass 
39 
26 
4 
5 
Fertile Meadow Grass 
78 
65 
6 
7 
Roughish Meadow Grass .... 
39 
29 
5 
6 
Crested Dog’s-tail Grass .... 
35 
28 
3 
4 
Spiked Fescue Grass 
19 
15 
2 
T „ 
2 
Sweet-scented Soft Grass .... 
82 
72 
4 
6 
Sweet-scented Vernal Grass . . . 
50 
43 
4 
3 
Fiorin 
54 
46 
5 
1 
2 
Fiorin cut in Winter 
76 
64 
8 
1 
3 
Section XIX. Phenomena and Products of Fermentation. 
1870. The term fermentation is employed to signify the spontaneous 
ehanges, which certain vegetable solutions undergo, placed under cer- 
tain circumstances, and which terminate either in the production of an 
intoxicating liquor, or of vinegar ; the former termination constituting 
vinous, the latter acetous fermentation. 
The principal substance concerned in vinous fermentation is sugar ; 
and no vegetable juice can be made to undergo the process, which does 
not contain it in a very sensible quantity. In the production of beer, 
the sugar is derived from the malt; in that of wine, from the juice of 
the grape. 
1871. In the manufacture of freer, the malt is ground and infused in 
the 7nash-tun, in rather more than its bulk of water, of the temperature 
of 160° or 180°. Here the mixture is stirred for a few hours ; the 
liquor is then run off, and more water added, until the malt is exhaust- 520 
WINE. 
ed. - These intusions are called won, and us principal contents are 
saccharine matter, starch, mucilage, and a small quantity of gluten. 
The strength of the wort is adjusted by its specific gravity, which is 
usually found by an instrument not quite correctly called a saccharo- 
meter, since it is influenced by all the contents of the wort, and not by 
the sugar only. It is a brass instrument, of the shape shown in 
the margin, so adjusted in weight as to sink to the 
point marked 0°, in distilled water, at the tempera- 
ture of 70°, and when immersed in a liquor of the 
same temperature, and of the specific gravity of 
1.100, it is buoyed up to the mark 100, just above 
the bulb. The intermediate space is divided into 
100 equal parts, and consequently will indicate in- 
termediate degrees of specific gravity. This is the 
most useful form of the instrument, though not that 
in common use. The specific gravity of the wort 
for ale is usually about 1.090 to 1.100, and for ta- 
ble-beer from 1.020 to 1.030. 
The wort is next boiled with hops, amounting up- 
on the average, to the weight of the malt, their 
use being to cover the sweetness of the liquor by 
their aromatic bitter, and to diminish its tendency 
to acidify. The liquor is then thrown into large, 
but very shallow, vessels, or coolers, where it is 
cooled to about 50°, as quickly as possible; it is 
then suffered to run into the fermenting vat, having 
been previously mixed with a proper quantity of 
yeast, which accelerates fermentation, apparently 
by virtue of the gluten which it contains. 
In the fermenting vessel, the different substances 
held in solution in the liquor begin to act upon each 
other ; an intestine motion ensues, the temperature 
of the liquor increases, carbonic acid escapes in large quantities ; at 
length this evolution of gas ceases, the liquor becomes quiet and clear, 
and it has now lost much of its sweetness, has diminished in specific gra- 
vity, acquired a new flavour, and become intoxicating. 
1872. The distillers prepare a liquor, called wash, for the express 
purpose of producing from it ardent spirits ; instead of brewing this 
from pure malt, they chiefly employ raw grain, mixed with a small 
quantity only of malted grain ; the water employed in the mashtun is of 
a lower temperature than that requisite in brewing, and the mashing 
longer continued ; by which it would appear that a part of the starch 
of the barley is rendered into a kind of saccharine matter. The wort 
is afterwards fermented with yeast. 
1873. Wine is principally procured from the juice of the grape, and 
some other saccharine and mucilaginous juices of fruits. The principal 
substances held in solution in grape juice are, sugar, gum, gluten, and 
bi-tartrate of potassa. It easily ferments spontaneously at tempera- 
tures between 60° and 80°, and the phenomena it gives rise to closely 
resemble those of the wort with yeast. After the operation, its speci- 
fic gravity is much diminished, its flavour changed, and it has acquired 
intoxicating powers. 
1874. If a mixture of 1 part of sugar, 4 or 5 of water, and a little 
Hydrometer. ALCOHOL. 
521 
yeast, be placed in a due temperature, it also soon begins to ferment, 
and gives rise to the same products as wort or grape-juice ; and, as the 
free admission of air is not necessary to vinous fermentation, its results 
may easily be examined by suffering the process to go on in the follow- 
ing apparatus ; consisting of a matrass containing the fermenting mix- 
ture, with a bent tube issuing from it, and passing into an inverted jar 
standing in water. 
It will thus he found that the only gaseous product is carbonic acid : 
and consequently, that carbon and oxygen are the principles which the 
saccharine matter loses during the process. 
1875. When any of the above-mentioned fermented liquors are dis- 
tilled, they afford a spirituous liquor; that from wine is termed brandy ; 
from the fermented juice of the sugar-cane we obtain rum; and from 
wash, malt spirit; and these spirituous liquors, by re-distillation, fur- 
nish spirit of wine, ardent spirit, or alcohol. 
1876. The different fermented liquors furnish very different pro- 
portions of alcohol, and it has been sometimes supposed that it does 
not pre-exist to the amount in which it is obtained by distillation ; but 
some experiments which I made upon the subject, in 1811 and 1813, 
and which are printed in the Philosophical Transactions for those years, 
tend to show that it is a real educt, and not formed by the action of 
heat upon the elements existing in the fermented liquor. The follow- 
ing Table exhibits the proportion of alcohol, specific gravity .825 at 
60°, by measure, existing in 100 parts of several kinds of wine and 
other liquors: 
Gaseous pro. 
ducts of fer- 
mentation. 
J. Lissa 
Proportion of Spirit 
per cent, by measure. 
- - - - 26.47 
Ditto 
- - 
24.35 
Average - 
2. Raisin wine - 
25.41 
26.40 
Ditto - - 
- 
25.77 
Ditto 
- 
23.20 
3. Marsala - 
Average - 
25.12 
26.03 
Ditto 
- 
25.05 
4. Port - - 
Average - 
25.09 
25.83 
Ditto - -. 
24.29 
Ditto - - 
Proportion of Spirit 
percent, by measure. 
- - - 23.71 
Ditto - - 
- - 
- 
23,39 
Ditto - - 
- - 
- 
22.30 
Ditto - - 
- - 
- 
21.40 
Ditto - - 
- - 
- 
19.00 
Average 
- 
22.96 
5. Madeira 
- - 
- 
24.42 
Ditto - - 
f* 
- 
23 93 
Ditto (Sercial) 
- - 
- 
21.40 
Ditto - - 
- - 
- 
19.24 
Average- 
- 
22.27 
6. Currant wine 
- - 
- QUANTITY OF ALCOHOL IN WINES. 
Proportions of Spirit 
percent, by 
measure. 
7. Sherry - - - - 
- 
19.81 
Ditto - - - - 
- 
19.83 
Ditto - - - - 
. 
18.79 
Ditto - - - - 
. 
18 25 
Average 
- 
19.17 
8. Teneriffe - - - 
- 
19.79 
9. Colares - - - 
- 
19.75 
10. Lachryma Christi 
- 
19.70 
11. Constantia, white 
- 
19.75 
12. Ditto, red - - - 
- 
18.92 
13. Lisbon - 
- 
18.94 
14. Malaga - - - - 
- 
18.94 
15. Bucellas - - - 
- 
18.49 
16. Red Madeira - - 
- 
22.30 
Ditto - - - - 
- 
18.40 
Average 
- 
20.35 
17. Cape Muschat - - 
- 
18.25 
18. Cape Madeira - - 
- 
22.94 
Ditto - - - - 
- 
20.50 
Ditto ... - 
- 
18.11 
Average 
- 
20.51 
19. Grape wine - - 
- 
18.11 
20. Calcavella - - - 
- 
19.20 
Ditto 
18.10 
Average 
- 
18.65 
21. Vidonia- - 
. 
19.25 
22. Alba Flora - - - 
. 
17.26 
23. Malaga - 
- 
17.26 
24. White Hermitage - 
- 
17.43 
25. Rousillon- - 
. 
19.00 
Ditto - - - - 
- 
17.26 
Average 
- 
18.13 
26. Claret 
17.11 
Ditto .... 
■ - 
16.32 
Ditto .... 
. 
14.08 
Ditto - - - - 
- 
12.91 
Average 
- 
15.10 
27. Zante - - : - 
. 
17.05 
28. Malmsey Madeira 
- 
16.40 
29. Lunel - - - - 
. 
15.52 
30. Sheraaz ... 
- 
15.52 
31. Syracuse ... 
15.28 
32. Sauterne - - - 
. 
14.22 
33. Burgundy - - - 
- 
16.60 
Proportions of Spirit 
percent.by: 
measure. 
Ditto .... 
15.22 
Ditto .... 
- 
14.53 
Ditto ... - 
- 
11.95 
Average 
- 
14.57 
34. Hock .... 
- 
14.37 
Ditto .... 
- 
13.00 
Ditto (old in cask) 
- 
8.88 
Average 
- 
12 08 
35. Nice - - - - 
- 
14.63 
36. Barsac - - - - 
. 
13.86 
37. Tent - - - - 
- 
13.30 
38. Champagne (still) 
- 
13.80 
Ditto (sparkling) - 
- 
12.80 
Ditto (red) - - 
- 
12.56 
Ditto (ditto) - - 
- 
11.30 
Average 
- 
12.61 
39. Red Hermitage- - 
- 
12.32 
40. Vin de Grave - - 
- 
13.94 
Ditto - - - - 
- 
12.80 
Average 
- 
13.37 
41. Frontignac (Rivesalte) 
12.79 
42. Cote Rotie - - - 
- 
12.32 
43. Gooseberry wine - 
- 
11.84 
44. Orange wine—average < 
of 
6 samples made by 
a 
London manufacturer 
11.26 
45. Tokay - - ' - - 
- 
9.88 
46. Elder wine - - 
- 
8.79 
47. Cider, highest average 
9.87 
Ditto, lowest ditto 
- 
5.21 
48. Perry,average of 4 samp 
. 7.26 
49. Mead - 
- 
7.32 
50. Ale (Burton) - - 
- 
8.88 
Ditto (Edinburgh) 
- 
6.20 
Ditto (Dorchester) 
- 
5.56 
Average 
- 
6.87 
51. Brown Stout - - 
- 
6.80 
52. London Porter (average) 
\ 4.20 
53. Ditto small beer (ditto) 
1.28 
54. Brandy - 
- 
53.39 
55. Rum - - - - 
- 
53.68 
56. Gin - 
- 
51.60 
57. Scotch Whiskey 
- 
54.32 
58. Irish ditto - - 
- 
53.90 
1877. The principle upon which the intoxicating properties of fer- 
mented liquors depends, and which exists in ardent spirits, is in .its 
purest form called alcohol. It may be obtained by distilling the recti- 
fied spirit oj wine of commerce, with one-fourth of its weight of dry 
and warm carbonate of potassa; about three-fourths may be drawn 
over. There are other substances which may be used as substitutes 
for the carbonate, especially muriate of lime. ZROPERTIES OF ALCOHOL. 
523 
1878. Alcohol thus obtained by slow and careful distillation, is a 
limpid, colourless liquid, of an agreeable smell, and a strong pungent 
flavour. Its specific gravity varies with its purity ; the purest obtain- 
ed by rectification over muriate of lime being 791 ; as it usually oc- 
curs it is .820 at*60°. If rendered as pure as possible by simple dis- 
tillation, it can scarcely be obtained of a lower specific gravity than 
.825, at 60°. 
1879. Alcohol has never been frozen, and consequently is particu- 
larly useful in the construction of thermometers intended to measure 
intense degrees of cold. When of a specific gravity of .825, it boils at 
the temperature of 176°, the barometrical pressure being 30 inches. 
In the vacuum of an air-pump it boils at common temperatures. The 
specific gravity of the vapour of alcohol, compared with atmospheric 
air, is 1.613.—Gay-Lussac, Annales de Chimie et Phys. Tom. i. 
1880. Alcohol may be mixed in all proportions, with 
water, and the specific gravity of the mixture is greater 
than the mean of the two liquids, in consequence of a dimi- 
nution of bulk that occurs on mixture as may be shown by 
the following experiment: 
The annexed wood-cut represents a tube with two bulbs, 
communicating with each other, the upper one being sup- 
plied with a well-ground glass stopper. Fill the tube and 
lower bulb with water, pour alcohol slowly into the upper 
bulb, and when full put in the stopper. The vessel will 
now be completely filled, the alcohol lying upon the water ; 
if it be inverted, the alcohol and water will slowly mix, and 
the condensation that ensues will be indicated by the empty 
space in the tube. A considerable rise of temperature 
takes place in this experiment, in consequence of the con- 
densation. 
1881. The strength of such spirituous liquors as consist 
of little else than water and alcohol, is of course ascertained 
by their specific gravity ; and for the purpose of levying 
duties upon them, this is ascertained by the hydrometer ; an 
instrument constructed upon the same principle as that de- 
scribed at page 520. But the only correct mode of ascer- 
taining the specific gravity of liquids, is by weighing them 
in a delicate balance, against an equal volume of pure water, 
of a similar temperature (507). 
1882. In the Philosophical Transactions for 1794, Mr Gilpin has giv- 
en a copious and valuable series of tables of the specific gravity of 
mixtures of alcohol and water, and of the condensation that ensues, 
with several other particulars. These are extremely useful, as ena- 
bling us to ascertain, without difficulty, the relative quantity of alcohol 
contained in any mixture of known specific gravity. 
The original tables are extremely voluminous, and have been vari- 
ously abridged by different persons ; I have, however, thought it most 
useful to insert two of them, adapted to the temperature of 60°, and 
refer the reader to Mr. Gilpin’s paper for those calculated at other 
temperatures. 
Alcohol. 
Condensation 
of Alcohol & 
water. 524 
TABLE OF THE SPECIFIC GRAVITY OP 
TABLE 
Of the Specific Gravity and Composition of Mixtures of Alcohol and 
Water at the Temperature of 60°. 
I. 
Spirit and 
Water 
by Weight. 
II. 
Specific 
Gravity. 
111. 
Spirit 
by 
Measure. 
IV. 
Water 
by 
Measure. 
V. 
Bulk 
of 
Mixture. 
VI. 
Diminu- 
tion of 
Bulk. 
VII. 
Quantity 
of 
Spirit 
per Cent. 
by Measure. 
Sp. + W. 
100+ o 
.82500 
100 
— 
100.00 
- - 
100.00 
1 
.82731 
—- 
0.83 
100.72 
0.11 
99.29 
2 
.82957 
— 
1.65 
101.44 
0.21 
98.58 
3 
.83177 
— 
2.47 
102.16 
0.31 
97.88 
4 
.83391 
— 
3.30 
102.89 
0.41 
97.19 
100+ 5 
.83599 
— 
4.12 
103.62 
0.50 
96.51 
6 
.83802 
— 
4.95 
104.35 
0.60 
95.83 
7 
.84001 
— 
5.77 
105.09 
0.68 
95.16 
8 
.84195 
— 
6.60 
105.83 
0.77 
94.50 
9 
.84384 
*—* 
7.42 
106.57 
0.85 
93.84 
100+10 
.84568 
— 
8 25 
107.31 
0.94 
93.19 
11 
.84748 
— 
9.07 
108.05 
1.02 
92.55 
12 
.84924 
— 
9.90 
108.80 
1.10 
91.91 
13 
.85096 
— 
10.72 
109.55 
1.17 
91.28 
14 
.85265 
— 
11.55 
110.30 
1.25 
90.66 
100+15 
.85430 
— 
12.37 
111.05 
1.32 
90.04 
16 
.85592 
— 
13.20 
111.81 
1.39 
89.44 
17 
.85750 
—. 
14.02 
112.56 
1.46 
88.84 
18 
.85906 
— 
14.85 
113.32 
1.53 
88.25 
19 
.86058 
— 
15.67 
114.08 
1.59 
87.66 
100+20 
.86208 
— 
16.50 
114.84 
1.66 
87.08 
21 
.86355 
— 
17.32 
115.60 
1.72 
86.51 
22 
.86500 
— 
18.15 
116.36 
1.79 
85.94 
23 
.86642 
— 
18.97 
117.12 
1.85 
85.38 
24 
.86781 
— 
19.80 
117.88 
1.92 
84.83 
100+25 
.86918 
20.62 
118 64 
1.98 
84.28 
26 
.87052 
— 
21.45 
119.41 
2.04 
83.74 
27 
.87183 
— 
22.27 
120.18 
2.09 
'83.21 
28 
.87314 
— 
23.10 
120.94 
2.16 
82.68 
29 
.87442 
— 
23.92 
121.71 
2.21 
82.16 tttres of ALCOHOL and WATER. 
I. 
Spirit and 
Water 
by Weight 
II. 
Specific 
Gravity. 
III. 
Spirit 
by 
Measure. 
IV. 
Water 
by 
Measure. 
V. 
Bulk 
of 
Mixture. 
VI. 
Diminu- 
tion of 
Bulk. 
VII. 
Quantity 
of 
Spirit 
per Cent. 
by Measure. 
Sp.+W. 
100+30 
.87569 
100 
24.75 
122.48 
2.27 
81.65 
31 
.87692 
— 
25.57 
123.24 
2.33 
81.14 
32 
.87814 
— 
26.40 
124.01 
2.39 
80.64 
33 
.87935 
— 
27.22 
124.78 
2.44 
80.14 
34 
.88053 
— 
28.05 
125.55 
2.50 
79.65 
100+35 
.88169 
— 
28.87 
126.32 
2.55 
79.16 
36 
.88283 
— 
29.70 
127.09 
2.61 
78.68 
37 
.88395 
— 
30.52 
127.86 
2.66 
78.21 
38 
.88505 
— 
31.35 
128.64 
2.71 
77.74 
39 
.88613 
— 
32.17 
129.41 
2.76 
77.27 
100+40 
.88720 
33.00 
130.19 
2.81 
76.81 
41 
.88825 
— 
33.82 
130.96 
2.86 
76.36 
42 
.88929 
— 
34.65 
131.74 
2.91 
75.91 
43 
.89032 
— 
35.47 
132.51 
2.96 
75.47 
44 
.89133 
— 
36.30 
133.29 
3.01 
75.03 
100+45 
.89232 
— 
37.12 
134.06 
3.06 
74.59 
46 
.89330 
— 
37.95 
134.84 
3.11 
74.16 
47 
.89427 
— 
38.77 
135.61 
3.16 
73.74 
48 
.89522 
— 
39.60 
136.39 
3.21 
73.32 
49 
.89615 
— 
40.42 
137.17 
3.25 
72.90 
100 + 50 
.89707 
— 
41.25 
137.95 
3.30 
72.49 
51 
.89797 
— 
42.07 
138.73 
3.34 
72.08 
52 
.89886 
— 
42.90 
139.51 
3.39 
71.68 
53 
.89973 
— 
43.72 
140.29 
3.43 
71.28 
54 
.90059 
— 
44.55 
141.07 
3.48 
70.89 
100+55 
.90144 
— 
45.38 
141.86 
3.52 
70.49 
56 
.90227 
— 
46.20 
142.64 
3.56 
70.11 
57 
.90309 
— 
47.02 
143.42 
3.60 
69.72 
58 
.90391 
— 
47.85 
144.21 
3.64 
69.34 
59 
.90470 
— 
48.67 
144.99 
3.68 
68.97 
100+60 
.90549 
— 
49.50 
145.78 
3.72 
68.60 
61 
.90626 
— 
50.32 
146.56 
3.76 
68.23 
62 
.90703 
— 
51.15 
147.35 
3.80 
67.87 
63 
.90778 
— 
51.97 
148.13 
3.84 
67.51 
64 
.90853 
— 
52.80 
148.92 
3.88 
67.15 526 
TABLE OP THE SPECIFIC GRAVITY OF 
I. 
II. 
III. 
IV. 
V. 
VI. 
VII. 
Spirit and 
Specific 
Spirit 
Water 
Bulk 
Diminu- 
Quantity 
by Weight. 
by 
by 
of 
tion of 
Spirit 
Gravity. 
per Cent. 
Sp.+W. 
Measure. 
Measure. 
Mixture. 
Bulk. 
by Measure. 
100+65 
.90927 
100 
53.62 
149.71 
3.91 
66.80 
66 
.91001 
— 
54.45 
150.50 
3.95 
66.45 
6 7 
.91074 
— 
55.27 
151.28 
3.99 
66.10 
68 
.91146 
— 
56.10 
152.07 
4.03 
65.76 
69 
.91217 
— 
56.92 
152.85 
4.07 
65.42 
100+70 
.91287 
_ 
57.75 
153.64 
4.11 
65.09 
71 
.91356 
— 
58.57 
154.42 
4.15 
64.76 
72 
.91424 
— 
59.40 
155.21 
4.19 
64.43 
73 
.91491 
— 
60.22 
156.00 
4.22 
64.10 
74 
.91557 
— 
61.05 
156.79 
4.26 
63.78 
100+75 
.91622 
61.87 
157.58 
4.29 
63.46 
76 
.91686 
— 
62.70 
158.37 
4.33 
63.14 
77 
.91748 
— 
63.52 
159.16 
4.36 
62.83 
78 
.91811 
— 
64.35 
159.95 
4.40 
62.52 
79 
.91872 
— 
65.17 
160.74 
4.43 
62.21 
100 + 80 
.91933 
- 
66.00 
161.53 
4.47 
61.91 
81 
.91933 
— 
66.82 
162.32 
4.50 
61.61 
82 
.92052 
— 
67.65 
163. i 1 
4.54 
61.31 
83 
.92110 
— 
68.47 
163.90 
4.57 
61.01 
84 
.92168 
— 
69.30 
164.70 
4.60 
60.72 
100 + 85 
.92225 
70.12 
165.49 
4.63 
60.43 
86 
.92281 
— 
70.95 
166.29 
4.66 
60.14 
87 
.92336 
— 
71.77 
167.08 
4.69 
59.85 
88 
.92391 
— 
72.60 
167.87 
4.73 
59.57 
89 
.92445 
— 
73.42 
168.66 
4.76 
59.29 
100+90 
.92499 
74.25 
169.46 
4.79 
59.01 
91 
.92552 
— 
75.07 
170.25 
4.82 
58.73 
92 
.92604 
— 
75.90 
171.05 
4.85 
58.46 
93 
.92656 
— 
76.72 
171.84 
4.88 
58.19 
94 
.92707 
— 
77.55 
172.64 
4.91 
57.92 
100+95 
.92758 
78.37 
173.43 
4.94 
57.66 
96 
.92807 
— 
79.20 
174.23 
4.97 
57.40 
97 
.92856 
— 
80.02 
175.02 
5.00 
57.14 
98 
.92905 
— 
80.85 
175.82 
5.03 
56.88 
99 
.92954 
— 
81.68 
176.62 
5.06 
56.62 MIXTURES OF ALCOHOL AND WATER. 
I. 
Water 
and Spirit 
by Weight. 
II. 
Specific 
Gravity. 
III. 
Spirit 
by 
Measure. 
IV. 
Water 
by 
Measure. 
V. 
Bulk 
of 
Mixture. 
VI. 
Diminu- 
tion of 
Bulk. 
VII. 
tiuantitv 
of 
Spirit 
per Cent. 
by Measure. 
Sp.+W. 
100+ 100 
.93002 
100 
82.50 
177.41 
5.09 
56.36 
99 
.93051 
— 
83.34 
178.22 
5.12 
56.11 
98 
.93102 
— 
84.19 
179.05 
5.14 
55.85 
97 
.93149 
— 
85.02 
179.89 
5.13 
55.59 
96 
.93198 
— 
85.94 
180.74 
5.20 
55.33 
100+95 
.93247 
— 
86.84 
181.61 
5.23 
55.06 
94 
.93296 
— 
87.76 
182.50 
5.26 
54.79 
93 
.93345 
— 
88.71 
183.42 
5.29 
54.52 
92 
.93394 
— 
89.67 
184.35 
5.32 
54.24 
91 
.93443 
— 
90.66 
185.31 
5.35 
53.96 
100+90 
•93493 
— 
91.67 
186.29 
5.38 
53.68 
89 
.93544 
— 
92.70 
187.29 
5.41 
53.39 
88 
.93595 
— 
93.75 
188.31 
5.44 
53.10 
87 
.93646 
— 
94.83 
189.35 
5.48 
52.81 
86 
.93697 
— 
95.93 
190.42 
5.51 
52.51 
100+85 
.93749 
— 
97.06 
191.53 
5.53 
52.21 
84 
.93802 
— 
98.21 
192.65 
5.56 
51.91 
83 
.93855 
— 
99.39 
193.80 
5.59 
51.60 
82 
.93909 
— 
100.61 
194.99 
5.62 
51.29 
81 
.93963 
— 
101.85 
196.20 
5.65 
50.97 
100+80 
.94018 
— 
103.12 
197.44 
5.68 
50.65 
79 
.94073 
— 
104.43 
198.71 
5.72 
50.32 
78 
.94128 
— 
105.77 
200.01 
5.76 
50.00 
77 
.94184 
— 
107.14 
201.35 
5.79 
49.66 
76 
.94240 
— 
108.55 
202.73 
5.82 
49.33 
100+75 
.94296 
— 
110.00 
204.15 
5.85 
48.98 
74 
.94352 
— 
111.48 
205.60 
5.88 
48.64 
73 
.94408 
— 
113.01 
207.10 
5.91 
48.29 
72 
.94466 
— 
114.58 
208.64 
5.94 
47.93 
71 
.94522 
— 
116.20 
210.22 
5.98 
47.57 
100+70 
.94579 
— 
117.86 
211.84 
6.02 
47.20 
69 
.94637 
— 
119.56 
213.51 
6.05 
46.83 
68 
.94696 
— 
121.32 
215.24 
6.08 
46.46 
67 
.94756 
— 
123.13 
217.02 
6.11 
46.08 
66 
.94816 
— 
125.00 
218.85 
6.15 
45.69 TABLE OF THE SPECIFIC GRAVITY OF 
I. 
Water and 
Spirit by 
Weight. 
II. 
Specific 
Gravity. 
III. 
Spirit 
by 
Measure. 
IV. 
Water 
by 
Measure. 
V. 
Bulk 
of 
Mixture 
VI. 
Diminu- 
tion of 
Bulk. 
VII. 
Quantity 
of 
Spirit 
per Cent. 
by Measure. 
W. + Sp. 
100 + 65 
.94876 
100 
126.92 
220.74 
6.18 
45.30 
64 
.94936 
— 
128.90 
222.69 
6.21 
44.91 
63 
.94997 
— 
130.95 
224.70 
6.25 
44.50 
62 
.95058 
— 
133.06 
226.78 
6.28 
44.10 
61 
.9511 
— 
135.25 
228.93 
6.32 
43.68 
100+60 
.95181 
— 
137.50 
231.14 
6.36 
43.26 
59 
.95243 
— 
139.82 
233.44 
6.38 
42.84 
58 
,95305 
— 
142.23 
235.82 
6.41 
42.41 
57 
.95368 
— 
144.73 
238.28 
6.45 
41.97 
56 
.95430 
— 
147.32 
240.82 
6.50 
41.52 
100+55 
.95493 
150.00 
243.47 
6.53 
41.07 
54 
.95555 
— 
152.77 
246.22 
6.55 
40.61 
53 
.95617 
— 
155.65 
249.08 
6.57 
40.15 
52 
.95679 
— 
158.65 
252.05 
6.60 
39.67 
51 
.95741 
— 
161.77 
255.14 
6.63 
39.19 
100+50 
.95804 
— 
165.00 
258.34 
6.66 
38.71 
49 
.95867 
— 
168.37 
261.68 
6.69 
38.21 
48 
.95931 
— 
171.87 
265.16 
6.71 
37 71 
47 
.95995 
— 
175.53 
268.80 
6.73 
37.20 
46 
.96058 
— 
179.35 
272.59 
6.76 
36.68 
100+45 
.96122 
183.34 
27 6.56 
6.78 
36.16 
44 
.96185 
— 
187.50 
280.70 
6.80 
35.6 3 
43 
.96248 
— 
191.86 
285.05 
6.81 
35.08 
42 
.96311 
— 
196.43 
289.60 
6.88 
34.53 
41 
.96374 
— 
201.21 
294.38 
6.88 
33.97 
100+40 
.96437 
— 
206.25 
299.42 
6.83 
33.40 
39 
.96500 
— 
211.54 
304.71 
6.83 
32.82 
38 
.96563 
— 
217.10 
310.28 
6.82 
32.23 
37 
.96626 
— 
222.97 
316.15 
6.82 
31.63 
36 
.96689 
— 
229.17 
322.36 
6.81 
31.02 
109 + 35 
.96752 
235.71 
328.90 
6.81 
30.40 
. 34 
.96816 
— 
242.65 
335.84 
6.81 
29.78 
33 
.96880 
— 
250.00 
343.21 
6.79 
29.14 
32 
.96944 
— 
257.81 
351.04 
6.77 
28.49 
31 
j .97009 
— 
266.13 
359.38 
6.75 
27.83 MIXTURES OF ALCOHOL AND WATER, 
I. 
Water and 
Spirit by 
Weight. 
II. 
Specific 
Gravity. 
III. 
Spirit 
by 
Measure. 
IV. 
Water 
by 
Measure. 
V. 
Bulk 
of 
Mixture. 
VI. 
Diminu- 
tion of 
Bulk. 
VII. 
Quantity 
of 
Spirit 
per Cent. 
by Measure. 
W. + Sp. 
100+30 
.97074 
100 
275.00 
368.28 
6.72 
27.15 
29 
.97139 
— 
284.48 
377.79 
6.69 
26.47 
28 
.97206 
— 
294.64 
387.99 
6.65 
25.77 
27 
.97273 
— 
305.56 
398 95 
6.61 
25.07 
26 
.97340 
— 
317.31 
410.74 
6.57 
24.35 
100+25 
.97410 
— 
330.00 
423.48 
6.52 
23.61 
24 
.97479 
— 
343.75 
437.29 
6.46 
22.87 
23 
.97550 
— 
358.70 
452.31 
6.39 
22.11 
22 
.97622 
— 
375.00 
468.64 
6.36 
21.34 
21 
.97696 
— 
392.86 
486.58 
6.28 
20.55 
100+20 
.97771 
— 
412.50 
506.29 
6.21 
19.75 
19 
.97848 
— 
434.21 
528.08 
6.13 
18.94 
18 
.97926 
— 
458.33 
552.29 
6.04 
18.! 1 
17 
.98006 
— 
485.29 
579 34 
5.95 
17.26 
16 
.98090 
—- 
515.62 
609.76 
5.86 
16.40 
100+15 
.98176 
_ 
550.00 
644.25 
5.7 5 
15.52 
14 
.98264 
— 
589.29 
683.66 
5.63 
14.63 
13 
.98356 
— 
634.61 
729.10 
5.51 
13.72 
12 
.98452 
— 
687.50 
782.11 
5.39 
12.79 
11 
.98551 
— 
7s 0.00 
84/1.71 
3.26 
11.84 
100+10 
.98654 
825.00 
919.87 
5.13 
10.87 
9 
.98761 
— 
916.67 
1011.70 
4.97 
9.88 
8 
.98872 
— 
1031.25 
1126.44 
4.81 
8.88 
7 
.98991 
— 
1178.57 
1273.92 
4.65 
7.85 
6 
.99115 
— 
1375.00 
1470.52 
4.48 
6.80 
100+ 5 
.99244 
1650 00 
1745.70 
4.30 
5.73 
4 
.99380 
— 
2062.50 
2158.37 
4.13 
4.63 
3 
.99524 
— 
2760.00 
2846.04 
3.96 
3.51 
2 
.99675 
— 
4125.00 
4221.21 
3.79 
2.37 
1 
.99834 
— 
8250.00 
8346.38 
3.62 
1.20 COMBUSTION OF ALCOHOL. 
Strength, 
1883. There are other methods of judging of the strength of spiritu- 
ous liquors, which, though useful, are not accurate, such as the taste, 
the size and appearance of the bubbles when shaken, the sinking oi 
floating of olive oil in it, and the appearances that it exhibits when 
burned ; if it burns away perfectly to dryness, and inflames gunpowder 
or a piece of cotton immersed in it, it is considered as alcohol : the 
different spirituous liquors leave variable proportions of water when 
thus burned in a graduated vessel. 
1884. There is the greatest difficulty in ascertaining what is meant 
by the term proof spirit. Dr Thomson, quoting the Act of Parliament 
of 1762 (System, ii. 319), states, that at the temperature of 60°, the 
specific gravity of proof spirit should be 0.916 ; and he also observes, 
that proof spirit usually means a mixture of equal bulks of alcohol and 
water ; but the specific gravity of such a mixture will, of course, de- 
pend upon that of the standard alcohol, which is not specified. It ap- 
pears from Gilpin’s Tables, that spirit of the specific gravity .916 at 
60°, consists by weight, of 100 parts of alcohol, specific gravity .825, 
at 60°, and 75 of water; and, by measure, of 100 parts of the same 
alcohol, and 61.87 of water. From the Tables of Lowitz, quoted by 
Dr. Thomson, from Crell’s Annals (1796, i. 202), we learn, that 
equal weights of alcohol, specific gravity .796, at 60°, (and which may 
be regarded as pure alcohol,) and water, have a specific gravity of 
.917, which is very near legal proof, and which, according to Gilpin’s 
Tables, contains 62.8 parts per cent, of his alcohol, by measure. 
1885. Alcohol is extremely inflammable, and burns with a pale blue 
flame, scarcely visible in bright day-light. It occasions no fuliginous 
deposition upon substances held over it, and the products of its com- 
bustion are carbonic acid and water, the weight of the water consider- 
ably exceeding that of the alcohol consumed. According to Saussure, 
jun., 100 parts of alcohol afford, when burned, 130 parts of water, 
the production of which may be shown by substituting the flame of 
alcohol for that of water, in the apparatus described in the first 
of the work, under the Article Water (236, i.), and if the tube at 
its extremity be turned down into a glass jar, it will be found that a 
current of carbonic acid passes out of it, which may be rendered evi- 
dent by lime-water. 
There are some substances which communicate colour to the flame 
of alcohol; from boracic acid it acquires a greenish yellow-tint; nitre 
and the soluble salts of baryta cause it to burn yellow, and those of 
strontia give it a beautiful rose colour ; cupreous salts impart a fine 
green tinge. 
1886. Alcohol dissolves pure soda and potassa, but it does not act 
upon their carbonates : consequently, if the latter be mixed with al- 
cohol containing water, the liquor separates into two portions, the up- 
per being alcohol deprived to a considerable extent, of water, and the 
lower the aqueous solution of the carbonate. The alcoholic solution 
of caustic potassa was known in old pharmacy, under the name of Van 
Helmont’s Tincture of Tartar. Its use in purifying potassa has already 
been stated (544) ; if it be long kept it deposits small crystals of car- 
bonate of potassa, and becomes nearly black, from the decomposition 
of a portion of alcohol. Ammonia and the carbonate are both soluble 
in alcohol ; the greater number of the sulphates are insoluble in this 
menstruum, but it dissolves many of the. muriates and nitrates. It 
Properties of 
alcohol. ETHER. 
also dissolves the greater number of the acids. It absorbs many ga- 
seous bodies. It dissolves the vegetable acids, the volatile oils, the ro- 
sins, tan, and extractive matter, and many of the soaps; the greater 
number of the fixed oils are taken up by it in small quantities only 
but some dissolve largely. It may be remarked, that many errors ex- 
ist in the published estimates of the solubility of substances in alcohol, 
arising from the existence of water either in the solvent or substance 
dissolved. 
1887. When the vapour of alcohol is passed through a red-hot cop- 
per tube, it is decomposed, a portion of charcoal is deposited, and a 
large quantity of carburetted hydrogen gas is evolved. 
The most satisfactory experiments on the composition of alcohol 
are those of Saussure, as quoted by Dr. Thomson (System, ii. p. 327). 
He passed the alcohol through a red-hot porcelain tube, terminating in 
a glass tube six feet long and surrounded by ice ; all the products were 
carefully collected and weighed. The result of this analysis was, that 
100 parts of pure alcohol consist of 
Hydrogen 
13.70 
Carbon 
51.98 
Oxygen 
34.32 
100.00 
These numbers approach to 3 proportionals of hydrogen = 3 ; 2 of 
carbon, = 12; and 1 of oxygen, == 8. 
Or it may be regarded as composed of 
Olefiant gas 
61.63 
Water 
38.37 
100.00 
If we consider it as composed of 1 volume of olefiant gas, and 1 vo- 
lume of the vapour of water, the 2 volumes being condensed into 1, 
the specific gravity of the vapour of alcohol, compared with common 
air, will be 1.599, or, according to Gay-Lussac, 1.613. 
1888. When alcohol is submitted to distillation, with certain acids, 
a peculiar compound is formed, called ether, the different ethers being 
distinguished by the name of the acid employed in their preparation. 
a. Sulphuric Ether. 
1889. Sulphuric Ether is the most important of these compounds ; 
it is prepared as follows : Equal weights of alcohol and sulphuric acid 
are carefully mixed and introduced into a glass-retort placed in a sand- 
bath, to which is adapted a capacious tubulated glass globe, connect- 
ed with a receiver, as represented in the wood-cut at page 92. 
Raise the mixture in the retort to its boiling point as rapidly as possi- 
ble, and, keeping the receiver cool by water or ice, continue the dis- 
tillation, till opaque vapours appear in the retort; then remove the 
receiver, and agitate its contents with a little quick-lime ; after which 
pour off the clear liquor, and re-distil to the amount of three-fourths its 
original quantity with the same precautions as before. The ether may 
> Preparation. 532 
sulphuric Ether. 
be further purified by distilling it off muriate of lime. The London 
Pharmacopoeia directs the distillation of ether with potassa, for its pu- 
rification from sulphurous acid ; and Mr Richard Phillips, in his Ex- 
perimental Examination, has given the following directions for procur- 
ing ether for pharmaceutical purposes, which answer extremely well. 
“ Mix with 16 ounces of sulphuric acid, an equal weight of rectified 
spirit, and distil about 10 fluid ounces, add 8 ounces of spirit to the 
residuum in the retort, and distil about 9 fluid ounces ; or continue the 
operation until the contents of the retort begin to rise or the product 
becomes considerably sulphurous ; mix the two products, and if the 
mixture consist of a light and heavy fluid, separate them : add potash 
to the lighter, as long as it appears to be dissolved ; separate the ether 
from the solution of potash, and distil about nine-tenths of it, to be 
preserved as ether sulphuricus, the specific gravity of which ought to 
be at most .750.” 
1890. Preparing ether upon a large scale, it is found that 14 parts 
of alcohol (specific gravity .820) mixed with an equal weight of sulphu- 
ric acid (specific gravity 1.8,) and submitted to distillation, afford about 
8 parts of impure ether (specific gravity .770). To the residuum 7 
parts of alcohol may be added, and about 7f parts more of impure 
ether drawn off. These products, when mixed, have a specific gravi- 
ty of about .782, and when rectified by distillation on carbonate of po- 
tassa, afford 101 parts of ether, of a specific gravity of .735, and about 
3i parts of ethereal spirit, which is employed instead of an equal quan- 
tity of alcohol in the next operation. 
1891. When ether, obtained by the usual process, is washed with 
its bulk of water, its specific gravity is diminished, and the water em- 
ployed for washing it affords, on distillation, a considerable portion of 
alcohol. By re-distilling this washed ether with a little potassa, which 
keeps down the water, or by treating it with muriate of lime, it is ob- 
tained extremely light and pure. 
1892. Sulphuric ether is a transparent, colourless liquid, of a plea-, 
safit smell and a pungent taste ; it is highly exhilarating, and produces 
a degree of intoxication when its vapour is inhaled by the nostrils. 
Its specific gravity varies extremely with its purity. Lowitz is said to 
have procured it as light as .632. I have never obtained it lower than 
*700 ; and) as ordinarily prepared, its specific gravity varies between 
.730 and .760. 
It is extremely volatile, and when poured from one vessel into an- 
other, a considerable portion evaporates ; during its evaporation from 
surfaces, it produces intense cold, as may be felt by pouring it upon 
the hand ; and seen, by dropping it upon the bulb of a thermometer, 
which sinks to many degrees below the freezing point (91). The spe- 
cific gravity of the vapour of sulphuric ether, compared with atmos- 
pheric air, is, according to Gay-Lussac, as 2.586 to 1.000. 
At mean pressure, sulphuric ether, when of a specific gravity of 
.720, boils at 98°, and under the exhausted receiver of the air-pump, 
at all temperatures above-—20° ; hence, were it not for atmospheric 
pressure, ether would only be known in the state of vapour. 
In consequence of the cold produced during the vaporization of sul- 
phuric ether, the phenomena of boiling and freezing may be exhibit- 
ed in the same vessel. For this purpose procure a very thin flask 
Which fits loosely into a wine-glass, as shown in the margin. Pour & 
Properties. small quantity of ether into the flask,and ot 
water into the glass, and place the whole 
under the receiver of an air-pump ; dur- 
ing exhaustion, the ether will boil, and a 
crust of ice will gradually form upon the 
exterior of the flask. 
When subjected to a degree of cold 
equal to — 46°, sulphuric ether freezes. 
1893. Ether dissolves the resins, seve- 
ral of the fixed oils, and nearly all the vo- 
latile oils ; it also dissolves a portion of 
sulphur, and of phosphorus ; the latter 
solution is beautifully luminous when 
poured upon warm water, in a dark room. 
The fixed alcalis are not soluble in ether, but it combines with ammo 
nia. 
Ether dissolves the oxides of gold and platinum, and these solutions 
have been employed for coating steel with those metals, with a view 
to Ornament and as a defence from rust. If to a saturated solution o: 
gold or platinum, in nitro-muriatic acid, there be added about 3 parts 
by measure of good sulphuric ether, it soon takes up the metals, leav- 
ing the acid nearly colourless below the ethereal solution, which is tc 
be carefully decanted off; into this the polished steel is for an instan 
plunged, and immediately afterwards washed in water, or in a weak al 
caline solution. Though the coating of platinum is the least beautiful 
Mr. Stodart, who has made many experiments upon this subject, con- 
siders it as the best protection from rust. Polished brass may be coat- 
ed by the same process. These surfaces of gold and platinum, thougl 
very thin, are often a useful protection : with gold the experiment is 
particularly beautiful, and well illustrates the astonishing divisibility o: 
the metal. The ethereal solution of gold is not permanent, but, aftei 
a. time, deposits the metal in the form of a film, in which crystals o; 
gold are often perceptible. 
1894. Ether is sparingly soluble in water, and in alcohol it dissolves 
in all proportions. The spiritus cetheris sulphurici of the Pharmaco- 
poeia, is an alcoholic solution of ether. 
1895. Ether is highly inflammable, and in consequence of its vo- 
latility it is often kindled by the mere approach of a burning body ; s 
circumstance which renders it highly dangerous to decant, or open ves- 
sels of ether near a candle. 
The inflammability of ethereal vapour may be shown by passing s 
small quantity into a receiver, furnished with a brass stop-cock and 
pipe, and inverted over water at the temperature of 100°. The re- 
ceiver becomes filled with the vapour, which may be propelled and in- 
flamed ; it burns with a bright bluish white flame. 
1896. When ether is admitted to any gaseous body it increases its 
bulk. Oxygen thus expanded, produces a highly inflammable mix- 
ture ; if the quantity of oxygen be large, and of ether small, the mix- 
ture is highly explosive, and produces water and carbonic acid. 
1897. When the vapour of ether is passed through a red-hot tube 
it is decomposed, and furnishes a large quantity of carburetted hydro- 
gen gas. Its analysis has been performed in various ways ; M. Saus- 
sure, bv detonating ethereal vapour with oxygen, and ascertaining the 
SULPHURIC ETHER. 
Ultimate ana- 
lysis. OIL OF WINE. 
quantity of carbonic acid formed, and that of oxygen consumed, is led 
to consider the component parts of ether as, 
Hydrogen - 
- - - 14.40 
Carbon - - - - 
- - - 67.98 
Oxygen.... 
- - - 17.62 
100.00 
which proportions are equivalent to 
Olefiant gas - 
- - - 100 
Water - - - - 
Or, it maybe stated as consisting of 
5 proportionals of olefiant gas, 
7 X 5 = 35 
1 „ water 
„ =9 
44 
which numbers, reduced to ultimate components, give 
6 
proportionals of hydrogen . 
. 1X6=6. 
5 
,, carbon 
. 6 X 5 = 30 
1 
„ oxygen . 
. = 8 
44 
1398. By reverting to the composition of alcohol, the change effect- 
ed upon it by the sulphuric acid in the process of etherification will be 
evident, as also the rationale of the production of olefiant gas (421). 
Alcohol consists of 
Rationale of 
etherification 
Olefiant gas 
Water 
If we now remove the whole of the water, which may be effected 
by a due proportion of sulphuric acid, we obtain olefiant gas only ; but, 
if we only abstract half the water, we convert the alcohol into ether ; 
loot that either of these conversions are ever perfectly performed in 
any of our processes. 
1899. When a little ether is introduced into chlorine, the gas is ab- 
sorbed, and a peculiar compound results, in which muriatic acid is 
very perceptible ; if the ether be inflamed, a large quantity of char- 
coal is deposited, and muriatic acid gas is abundantly evolved. 
1900. If ether be mixed with its bulk of sulphuric acid, and submit- 
ted to distillation, a portion of it is converted into a peculiar fluid, 
which has been termed oil of wine; it is the olaum atthereum of the 
Pharmacopoeia. It has a sweetish taste, and a rich agreeable odour. 
It does not mix with water, but readily dissolves in ether and in alco- 
hol. It is very inflammable, and deposits a large quantity of carbon 
during its combustion. Its composition has not been inquired into. 
1901. The residue of the distillation of ether has been examined 
by several chemists. According to Sertuerner, new acid compounds 
arc produced, which he calls cenothionic acids. (Thomson’s Annals, xiv. 
44.) M. Vogel, in repeating these experiments, allows the formation 
of one new acid odIv, which he calls svlpliovinous acid; he obtained it NfTRIC ETHER. 
by saturating the residue of the distillation of ether with carbonate of 
lead ; the liquor being filtered, contained a soluble sulphoviuate of 
lead; sulphuretted hydrogen passed through this solution precipi- 
tated the lead and left the pure acid, which is so easily decomposed by 
heat as only to admit of concentration by evaporation under the ex- 
hausted receiver. 
1902. Sidphovinate of Baryta was obtained by Gay-Lussac, in rhom- 
boidal prisms terminated by a rhomboidal pyramid ; the crystals were 
transparent, and permanent, but easily decomposed by heat. 
1903. A strong analogy appears to subsist between the hyposul- 
phuric and sulphovinous acids ; and it will probably be found that the 
latter derives its peculiarities from the combination of a portion of ethe- 
real oil.—Annales de Chimie, xiii. Quarterly Journal of Science and 
Arts, ix. 397. 
1904. When ether is passed over red-hot platinum wire, or con- 
sumed in the lamp without flame, described in the chapter on Radiant 
Matter (191), a peculiar acid substance is produced, which has been 
subjected to an interesting series of experiments, by Mr. J. F. Daniell, 
(Quarterly Journal of Science and Arts, vi. 318.) He obtained it by 
placing the lamp, filled with ether, and properly trimmed with a coil of 
glowing platinum wire, under the head of an alembic, in which the va- 
pour was condensed, and collected in a phial applied to its beak. 
Lampic acid, for so Mr. Daniell has termed this product, is colour- 
less, sour, and pungent; its vapour is very irritating, and its specific 
gravity, when purified by carefully driving off a portion of alcohol 
which it contains, is about 1.015. It reddens vegetable blues, and de- 
composes the alcaline carbonates with effervescence. 
Mr. Daniell has described many of the combinations of this acid, 
which he terms lampates, and has given some experiments upon its 
composition, whence he deduces its ultimate components, as follow : 
1 
proportional carbon . . . 
. . 6 
1 
hydrogen . 
. . 1 
1 
9 
16 
When lampic acid is added to the solutions of silver, gold, platinum, 
mercury, and copper, and the mixture heated, the metals are thrown 
down in the metallic state. 
On distilling the lampate of mercury, made by digesting the perox- 
ide of mercury in the acid, Mr. Daniell obtained the concentrated or 
pure lampic acid, in the form of a very dense liquid with an intensely 
suffocating odour. 
b. Nitric Ether. 
1905. When strong nitric acid and alcohol are mixed in equal pro- 
portions, a violent action presently ensues ; there is a very copious 
evolution of an inflammable aeriform body, which has been called ni 
trous etherized gas, and which appears to be a compourld of nitrous 
ether, and nitric oxide. If we endeavour to condense the volatile pro- 
ducts, we find that the receiver contains alcohol, water, nitrous 
nitrous acid, and acetic acid ; and that the greater portion of the true 
ether has made its escape with the gaseous products. Thenard has 536 
FULMINATING MERCURY. 
paid much attention to this subject, and has given the following pro- 
cess for obtaining nitric ether (Memoires cT Arcueil, Tom. i., and 
Traite de Chimie, Tom. iii., p. 278.) : 
Introduce into a sufficiently capacious retort equal weights of alco- 
hol, (specific gravity 820) and of nitric acid of commerce (specific gra- 
vity 1.30) and connect it with five Wolfe’s bottles, the first of which 
is empty, and the remaining four half-filled with a saturated solution of 
salt in water. Apply a gentle heat to the retort, till the liquor begins 
to effervesce ; then withdraw the fire, and the gaseous matter passing 
through the bottles, which should be kept cold by ice, deposits the 
ether upon the saline solution, from which it is to be decanted, shaken 
with chalk, and re-distilled at a very gentle heat. 
1906. Nitric ether, thus prepared, has the following properties : It 
has a very powerful ethereal odour; its colour is pale yellow; its 
taste very pungent; its specific gravity above that of alcohol, but less 
than that of water. It is more volatile than sulphuric ether, and the 
heat of the hand is sufficient to produce its ebullition. It is soluble in 
48 parts of water ; and in all proportions in alcohol; this last solution 
is the spiritus eztheris nitrici, or sweet spirit of nitre, of the Pharmaco- 
poeia. It is decomposed by keeping, and nitric and acetic acids are 
formed in it. According to Thenard, nitric ether consists of 
Preparation-. 
Oxygen .... 
Carbon .... 
Nitrogen .... 
Hydrogen . . . 
100.00 
Dr. Thomson (System, Vol. ii , p. 341.) concludes, from analogy, 
that nitric ether consists of 4 proportionals of olefiant gas, = 28, and 
1 of nitric acid, = 54 ; or, of 
4 proportionals of hydrogen 
1 
X 
4=4 
4 carbon 
6 
X 
4 = 24 
1 nitrogen 
. 
. 
. . 14 
5 oxygen 
8 
X 
5 = 40 
82 
1907. When nitric acid, holding mercury or silver in solution, is 
added to alcohol, a white precipitate is formed during the efferves- 
cence that ensues, which is possessed of powerful detonating proper- 
lies. 
Fulminating Mercury was discovered by Mr. Howard who has given 
the following directions for its preparation : Dissolve 100 grains of 
mercury, in a measured ounce and a half of nitric acid, by the assist, 
ance of a gentle heat; pour this solution into two measured ounces of 
alcohol, previously put into an evaporating basin, and apply a gentle 
heat till an effervescence ensues ; when this has ceased, pour the li- 
quid off the precipitate which falls, collect it upon a filter, wash it with 
a small quantity of water, and dry it at a heat not exceeding 2129. 
Fulminating mercury thus prepared is in the form of small crystal-, 
line grains, of a whitish yellow or pale grey colour. A few grains MURIATIC ETHER. 
placed on a smooth anvil and struck with a hammer, detonate with a 
sharp stunning report; it also explodes by friction, heat, and electri- 
city ; and by the action of concentrated sulphuric acid, though with less 
noise. 
Mr. Howard considers this powder as a compound of oxalate of mer- 
cury and nitrous etherized gas : Fourcroy, however, has shown that 
its composition varies a little, under different circumstances of prepar- 
ing it.—Howard, Phil. Trans., 1800. 
1908. By a similar process nearly, a species of fulminating silver 
may be prepared. (Descotils, Nicholson’s Journal, Vol. xviii.) 
Upon three drachms of powdered nitrate of silver, pour two ounces 
and a half of alcohol, and add seven drachms, by measure, of nitric 
acid. When the effervescence has nearly ceased add a little water, 
wash the precipitate, and dry it in the open air, secluded from light.—- 
Accum’s Cher deal Amusement, 3d edit., p. 102. 
This very dangerous compound explodes upon slight friction, or 
when gently heated, or touched with sulphuric acid, and, upon the con- 
tact of a sharp piece of glass or rock crystal, it detonates even under 
water ; an electric spark also occasions its explosion. 
When exploded under slight pressure in contact of gunpowder, it in- 
flames it. 
The composition of this species of fulminating silver has not been 
ascertained with precision ; indeed, the subject is one of extreme dif- 
ficulty, in consequence of the new products that are formed by its sud- 
den decomposition. 
c. Muriatic Ether. 
1909. Muriatic ether was thus obtained by Thenard, (Memoirs cV 
Arcueil, Tom. i.) : Equal measures of strong liquid muriatic acid, and 
highly rectified alcohol, are put into a retort communicating with a 
receiver, from which a tube passes into a Wolfe’s bottle containing 
warm water, and having a tube of safety : from this there issues a 
bent tube passing into a bottle surrounded by ice. On applying heat 
to the retort, a portion of alcohol and acid pass into the first receiver, 
and the ether in a gaseous state escapes through the warm water and 
the bent lube, and is condensed in the cold vessel. 
1910. At a temperature somewhat below 70° muriatic etbcr passes 
into the state of vapour, of which the specific gravity is about 2.220, 
that of air being 1.000 ; it is highly inflammable, its taste sweetish and 
ethereal, and it is soluble in its own bulk of water at 64°. Its speci- 
fic gravity in a liquid state, at 40°, is .870. It is remarkable that this 
ether does not affect vegetable blues, nor does it afford traces of chlo- 
rine to the usual tests ; but, when burned, muriatic acid is immediate- 
ly perceptible. 
1911. According to Thenard, this ether, contains 
Preparation. 
Muriatic acid 
29.44 
Carbon 
Oxygen 
Hydrogen 
10.64 
100.00 538 
VINEGAR. 
Dr. Thomson considers muriatic ether as a compound of lour pro- 
portionals of olefiant gas, and one of muriatic acid; hence it would 
contain 
5 proportionals of hydrogen 
1X5= 5. 
4 carbon 
6X4= 24. 
1 chlorine. 
36 
65 
d. Hydriodic Ether. 
1912. By distilling two measures of alcohol, with one of concen- 
trated liquid hydriodic acid, Gay-Lussac obtained an ethereal liquid, of 
a specific gravity of 1.920 at 72°, and requiring a temperature of 148° 
for its ebullition. Its properties have not been very satisfactorily in- 
vestigated, nor have any accurate experiments demonstrated its compo- 
sition.—Annales de Chimie, xci. 
Acetous Fermentation. 
1913. When any of the vinous liquors are exposed to the free ac- 
cess of atmospheric air at a temperature of 80° or 85°, they undergo 
a second fermentation, terminating in the production of a sour liquid, 
called vinegar. During this process a portion of the oxygen of the 
air is converted into carbonic acid ; hence, unlike vinous fermentation, 
the contact of the atmosphere is necessary, and the most obvious phe- 
nomenon is the removal of carbon from the beer or wine ; the vine- 
gar of this country is usually obtained from malt liquor, while wine is 
employed as its source in those countries where the grape is abundant- 
ly cultivated. 
1914. The colour of vinegar varies according to materials from 
which it has been obtained ; that manufactured in England is generally 
artificially coloured with burnt sugar : its taste and smell are agreeably 
acid. Its specific gravity is liable to much variation ; it seldom ex- 
ceeds 1.0250. When exposed to the air it becomes mouldy and pu- 
trid, chiefly in consequence of the mucilage which it contains, and 
from which it may be in some measure purified by careful distillation. 
Accordingto Mr R. Phillips, (Remarks on the London Pharmacopoeia,') 
when good malt vinegar of the specific gravity of 1.020 is distilled, the 
first eighth that passes over is of the specific gravity 0.997 ; the next 
six-eighths are of specific gravity 1.0023, and a fluid ounce decom- 
poses 8.12 grains of precipitated carbonate of lime. The lightness of 
the first portion is owing to its containing alcohol, consequently, in the 
Pharmacopoeia process it is ordered to be rejected. The term distilled 
vinegar, or dilute acetic acid, is properly applied to the second portion ; 
it is erroneously called acetic acid, in the Pharmacopoeia. The matter 
which remains in the still is empyreumatic, and generally contains 
some other vegetable acids : when the vinegar has been adulterated, 
which is not unfrequently the case, we sometimes find in it muriatic 
and sulphuric acids. 
1915. Distilled vinegar is colourless, and of a flat acid taste ; it con- 
sists essentially of the real acid diluted with water. To obtain acetic 
acid, or, as it has been sometimes called, radical vinegar, distilled vi- 
negar may be saturated with some metallic oxide, and the acetate thus 
obtained, subsequently decomposed. ACETIC ACID. 
539 
1916. Acetic acid is thus procured by distilling acetate of copper, or 
crystallized verdigris, in a glass retort heated gradually to redness : it 
requires re-distillation to free it from a little oxide of copper which 
passes over in the first instance. Acetic acid may also be obtained by 
distilling acetate of soda or acetate of lead with half its weight of sulphu- 
ric acid : or from a mixture of equal parts of sulphate of copper and 
acetate of lead ; in these cases, the acid passes over at a moderate tem- 
perature. 
1917. A considerable quantity of acetic acid is also now procured 
by the distillation of wood in the process of preparing charcoal for the 
manufacture of gunpowder. The liquor at first procured is usually 
termed pyroligneous acid; it is empyreumatic and impure, and seve- 
ral processes have been contrived to free it from tar and other matters 
which it contains. It may be saturated with chalk and evaporated, by 
which an impure acetate of lime will be obtained, and wrhich, mixed 
with sulphate of soda, furnishes, by double decomposition, sulphate of 
lime and acetate of soda : the latter distilled with sulphuric acid affords 
a sufficiently pure acetic acid, which by dilution with water may be 
reduced to any required strength. The purification of this acid has 
been brought to great perfection by Dr. Bollman. 
1918. Acetic acid obtained by these processes is transparent and 
colourless, its odour highly pungent and it blisters and excoriates when 
applied to the skin. Its specific gravity is 1.080. It is extremely 
volatile, and its vapour readily burns. It combines in all proportions 
with water, and when considerably diluted, resembles distilled vinegar. 
When highly concentrated, it crystallizes at the temperature of 40°, 
but liquefies when its heat is a little above that point. 
1919. According to Berzelius, whose analysis of acetic acid was very 
carefully conducted, (Thomson’s Annals, Vol.iv.) its ultimate-compo- 
nents are 
Carbon -------- 
46.83 
Oxygen 
46.82 
Hydrogen 
• 6-35 
100.00 
These numbers reduced to definite proportionals, are 
3 proportionals of hydrogen 
l 
X 
3=3 
4 carbon 
6 
X 
4 = 24 
3 oxygen 
8 
X 
3 = 24 
51 
Hence we see that there is no excess of oxygen in acetic acid, but 
lhat it consists of 
3 proportionals of water 9X3 = 
4 •- carbon 6X4 = 
= 27 
= 24 
51 
The chemist above quoted has given the composition of acetate of 
lead, at 100 acid -J- 217.5 oxide of lead, and 
217.5 : 100 :: 112 : 51.4 ACETATES. 
so that the number 51.5 may safely be adopted as the representative 
of acetic acid. 
1920. The acetates are all soluble in water, and mostly very solu- 
ble : many of them are deliquescent, and difficultly crystallizable; 
they are decomposed by sulphuric acid, and when submitted to des- 
tructive distillation, furnish a modified vinegar, which has been term- 
ed pyroacetic acid or spirit: these decompositions have been fully in- 
vestigated, and the properties of the pyroacetic spirit inquired into, by 
Mr. Chenevix.—Annates de Chimie, xlix. 
The following are among the most important of the acetates : 
1921. Acetate of Ammonia is a very deliquescent, soluble salt, and 
extremely difficultly crystallizable. In solution, obtained by saturating 
distilled vinegar with carbonate of ammonia, it constitutes the Liquor 
Ammonias acelatis of the Pharmacopoeia, which has long been used in 
medicine as a diaphoretic, under the name of spirit of Mindererus. 
1922. Acetate of Potassa is usually formed by saturating distilled 
vinegar with carbonate of potassa, and evaporating to dryness. If this 
salt be carefully fused, it concretes into a lamellar deliquescent mass on 
cooling. It is the terra foliata tartari, and febrifuge salt of Sylvtus of 
old pharmacy. It dissolves in its own weight of water at 60°, and the 
solution has an acrid saline taste. It consists of one proportional of 
each of its components, or 48 potassa +51.5 acetic acid = 99.5 ace- 
tate of potassa. 
1923. Acetate of Soda forms prismatic crystals, not deliquescent, of 
an acrid bitterish taste, and soluble in rather less than three parts ot wa- 
ter at 60°. It is the terra foliata crystallisata of old writers. It con- 
sists of 32. soda + 515 acetic acid. 
1924. Acetate of Lime, is a difficultly crystallizable salt, readily so- 
luble in water, and of a bitter saline taste ; consisting of 28 lime + 
51.5 acid. It is sometimes obtained by saturating the vinegar formed 
during the distillation of wood, and employed in the preparation of 
acetate of alumina, which is used by the calico-printers as a mordant. 
1925. Acetate of Baryta furnishes acicular crystals of a sour and 
bitterish taste : in cold weather the concentrated solution congeals in- 
to a silky congeries of crystals. It requires rather more than its own 
weight of water at 60° for solution, and consists of 51.5 acid+ 78. 
baryta. 
1926. Acetate of Strontia furnishes small permanent crystals, con- 
sisting of 51 5 acid + 52 strontia. 
1927. Acetate of Magnesia is uncrystallizable, and of a bitterish 
sweet taste. It consists of 51.5 acid + 20 magnesia. 
1928. Acetate of Manganese, formed by dissolving the protocarbonate 
n acetic acid, crystallizes in rhomboidal tables, permanent, and of a 
reddish colour and astringent metallic taste, soluble in3| parts of water 
at 60°. They consist of 70 acid and water + 30 protoxide of man- 
ganese.—John, Gehlen’s Journal, iv. 
1929. Acetate of Iron. The acetic acid combines with both oxides 
of iron. The protacetate is formed by digesting sulpburet of iron in 
acetic acid ; it yields green prismatic crystals, of a styptic taste, and 
readily soluble in water ; the solution becomes brown by exposure to 
air, and passes into peracetate, which is uncrystallizable, and obtained 
by digesting iron in acetic acid. This compound is extensively used 
by calico-printers, who prepare it either by digesting iron in pyrolig ACETATES. 
541 
iieous acid, or by mixing solution of acetate of lead with sulphate of 
iron, and exposing the filtered solution to air. 
1930. Acetate of Zinc is formed either by dissolving oxide of zinc in 
acetic acid, or by mixing a solution of sulphate of zinc with one of 
acetate of lead. It crystallizes in thin shining plates of a bitter and 
metallic taste, very soluble, but not deliquescent. This salt is some- 
times used in pharmacy, chiefly as an external application. According 
to Messrs. Aikin, the specific gravity of a saturated solution of acetate 
of zinc, made my digesting the salt in distilled vinegar, is 1055. Of 
this solution 900 grains contain 53 of drj% or 82.6 of crystallized ace- 
tate. One ounce by measure of the solution weighs 506 grains, and 
contains 29.8 grains of dry, or 46.5 grains of crystallized salt. 
1931. Acetate of Tin. This metal is slowly acted on by acetic acid, 
but a protacetate and peracetate of tin may be made by mixing acetate 
of lead with saturated solutions of the protomuriate and permuriate of 
tin. These solutions have been recommended as mordants for the use 
of dyers The protacetate is crystallizable. Vinegar kept in tin ves- 
sels dissolves a very minute portion of the metal; and in pewter ves- 
sels it likewise dissolves a small portion of the lead, where in contact 
both with the vinegar and air ; hence distilled vinegar, which has been 
condensed in a pewter worm, affords generally traces of both metals.— 
Vauquelin, Annales de Ckimie, xxxii. 
1932. Acetate of Copper. By exposing copper to the fumes of vine- 
gar, it becomes gradually incrusted with a green powder called verdi- 
gris , which is separable by the action of water, into an insoluble suba- 
cetate of copper, and a soluble acetate. 
Acetate of copper may be obtained by digesting verdigris, or oxide 
of copper, in acetic acid ; by evaporating this solution, it is obtained in 
prismatic crystals of a fine green tint. It dissolves sparingly in water 
and alcohol, and communicates a beautiful blue-green colour to the 
flame of the latter ; by distillation it affords a very pure acetic acid. 
According to Dr. Thomson, acetate of copper, in its crystallized state, 
consists of 
1 
proportional of acid 
. . 51.5 
1 
oxide of copper . 
. . 72. 
8 
7 9 
195.5 
1933. Acetate of Lead, is the sugar of lead, and salt of Saturn of 
the old chemists : it may be regarded as the most important of the ace- 
tates ; it is used in pharmacy, and by dyers and calico-printers for the 
preparation of acetate of alumina and of iron, which are formed by 
mixing its solution with that of the sulphates of those metals, an inso- 
luble sulphate of lead being at the same time produced. Acetate of 
lead is formed by digesting the carbonate in distilled vinegar, or in the 
acetic acid obtained by the destructive distillation of wood ; it usually 
occurs in masses composed of acicular crystals ; but by careful crystal- 
lization it may be obtained in quadrangular prisms. Its taste is sweet 
and astringent, and it is soluble in about four parts of water at 60°. It 
is sometimes improperly termed a superacetate, but the salt is neutral, 
though when dissolved in water containing the smallest portion of car- 
bonic acid, a white insoluble compound of lead falls, and a little acetic 
acid being liberated, the solution is rendered sour. ACETATES. 
Carbonic acid passed through a solution of acetate of lead, precipi- 
tates, as I am informed by Mr. James South, exactly half the quantity 
of the oxide which the salt contains ; hence a binacetate is probably 
formed which however does not afford crystals. 
According to the experiments of Berzelius, acetate of lead consists 
of 
Acetic acid 
Protoxide of lead . . . . 
Water 
. . . 14.32' 
' 
100 
hence the dry acetate is composed of 
1 proportional of acetic acid 
1 yellow oxide of lead . 
. . 112. 
163.5 
When acetate of lead is submitted to destructive distillation it fur- 
nishes a considerable quantity of a peculiar fluid, smelling and burning 
like alcohol.—Proust, Journal de Physique, Tom. lvi. 
1934. When 100 parts of sugar of lead are boiled in water with 
about 150 of yellow oxide, or of finely powdered litharge, a salt is ob- 
tained which crystallizes in plates, and is less sweet and soluble than 
the acetate ; it has been termed subacetate of lead, and consists accord- 
ing to Berzelius of 1 proportional of acid = 51.5 + 3 proportionals 
of oxide of lead 336. This compound has long been used in pharma- 
cy, under the name of Goulard’s extract of lead. It is very rapidly 
precipitated by carbonic acid, of which it is a most delicate test; it. 
also has a strong attraction for vegetable colouring matter, upon which 
principle I employed it in my analysis of wines.—Phil. Trans., 1813. 
1935. Acetate of Antimony, formed by digesting the protoxide in ace- 
tic acid, was once employed as an emetic. 
1936. Acetate of Bismuth may be formed by adding nitrate of bis- 
muth to a concentrated solution of acetate of potassa ; a precipitate 
falls, which re-dissolves on the application of heat, and afterwards af- 
fords scaly crystals. The addition of acetic acid to nitrate of bismuth 
prevents its precipitation when diluted.—Morveau, Encycl. Method. 
Chi mi e, i. 10. 
1937. Acetate of Cobalt may be obtained by digesting oxide of cobalt 
in acetic acid ; it is uncrystallizable, and furnishes a sympathetic ink, 
colourless when cold, but blue when heated. 
1938. Acetate of Uranium forms four-sided prismatic crystals of a 
yellow colour. 
1 939, Acetate of Titanium, not examined. 
1940. Acetate of Cerium. Recently precipitated oxide of cerium 
readily dissolves in acetic acid, and yields small crystals on evaporation, 
of a sweetish taste, permanent, and readily soluble in water.—Hisin- 
CiER and Berzelius, Gehlen’s Journal, ii. 414. 
1941. Acetate of jYickel forms green rhomboidal crystals. 
1942. Acetate of Mercury. Protacetate of Mercury is most readily 
formed by mixing a solution of protonitrate of mercury with acetate of 
potassa. For this purpose dissolve three ounces of mercury in about 
four ounces and a half of cold nitric acid, and mix this solution with ACETATES. 
three ounces of acetate of potassa previously dissolved in eight pints 
of boiling water, and set the whole aside to crystallize, which takes 
place as the liquor cools, and the acetate of mercury then separates in 
the form of micaceous crystalline plates, which are to be washed in 
cold water, and dried on blotting paper. (Edinburgh Pharmacopoeia.) 
In preparing this salt, the quantity of water for dissolving the acetate 
need not be so large as above directed, one pint being sufficient, but it 
is necessary to pour the mercurial solution into the acetate. This salt 
has an acrid taste, and is very difficultly soluble in water, requiring, 
according to Braconnot, (Annales de Chirnie, lxxxvi. 92.) 600 parts of 
water. It is insoluble in alcohol. It was once used in medicine. 
1943. Peracetate of Mercury is formed by digesting the peroxide in 
acetic acid ; it does not crystallize, and affords on evaporation a deli- 
quescent yellow mass, which is decomposed by water iuto a superper- 
acetate, which remains dissolved ; and an insoluble subperacetate.— 
Proust, Journal de Phys., lvi. 
1944. Acetate of Silver is obtained by boiling the acid on oxide of 
silver, or by mixing solutions of acetate of potassa and nitrate of silver ; 
it forms acicular crystals of an acrid metallic taste. 
1945. Acetate of Alumina. This salt is extensively employed by 
calico-printers as a mordant or basis for fixing colours ; they produce 
it by mixing solutions of alum and acetate of lead : about three pounds 
of alum are dissolved in eight gallons of water and a pound and a half 
of sugar of lead stirred into it; a copious formation of sulphate of lead 
ensues which is allowed to subside, and the clean liquor holding acetate 
of alumina and a portion of undecomposed alum in solution, is then drawn 
off, a portion of pearlash and chalk being added to it previous to use, 
in order to saturate any excess of acid. 
Acetate of alumina, formed by digesting recently precipitated alumina 
in acetic acid, may be procured in deliquescent acicular crystals of an 
astringent taste, and containing, according to Richter, 73.81 acid -f- 
26.19 alumina : hence it is probably a binacetate. 
When acetic acid and alcohol are repeatedly distilled together, a por- 
tion of acetic ether is formed, which has a peculiar and agreeable taste 
and smell, and a specific gravity of about .860 at 60°. It boils at about 
160°, is highly inflammable, and emits acetic acid among its products of 
combustion. This ether is directed in some of the foreign Pharmaco- 
poeia for medical use, and the following is perhaps the best process for 
its production. Introduce into a tubulated retort 3 parts of acetate of 
potassa, 3 of alcohol, and 2 of sulphuric acid, and distil to dryness. 
To the product add one-fifth its weight of sulphuric acid, and draw off 
by a gentle heat a quantity of ether equal to that of the alcohol origin- 
ally employed. 
Acetic ether is much more soluble in water than sulphuric ether : 
according to M. Thenard, water at dissolves about a 7.5 part of 
its weight, and the solution is permanent. Caustic potassa decomposes 
it, and forms acetate of potassa. 
Oxalic, citric, tartaric, and benzoic acids have been employed in the 
formation of ethers ; the prescence of a mineral acid is indispensable 
to their formation.—Ure’s Dictionary, Art. Ether. ANIMAL SUBSTANCES. 
CHAPTER IX. 
Of Animal Substances. 
1946. The different sections of this chapter will contain an account 
of the ultimate and proximate principles of the substances belonging 
to the animal creation, of the different methods of analysis by which 
these principles are obtained, and of such of the animal functions as 
are concerned in their production, where these are susceptible of 
chemical elucidation. 
Section I. Of the ultimate Principles of Animal Matter, and of 
the Products of its destructive Distillation. 
1947. The proximate principles of the animal creation consist, like 
those of vegetables, of a few elementary substances, which by combi- 
nation in various proportions, give rise to their numerous varieties. 
Carbon, hydrogen, oxygen, and nitrogen, are the principal ultimate 
elements of animal matter ; and phosphorus and sulphur are also often 
contained in it. The presence of nitrogen constitutes the most strik- 
ing peculiarity of animal, compared with vegetable bodies ; but as some 
vegetables contain nitrogen, so there are also certain animal principles, 
into the composition of which it does not enter. 
1948. The presence of nitrogen stamps a peculiarity upon the pro- 
ducts obtained by the destructive distillation of animal matter, and 
which are characterized by the presence of ammonia, formed by the 
union of the hydrogen with the nitrogen. It is sometimes so abun- 
dantly generated as to be the leading product; thus, when horn, hoofs, 
or bones, are distilled per se, d quantity of solid carbonate of ammonia, 
and of the same substance combined with empyreumatic oil, and dis- 
solved in water, are obtained ; hence the pharmaceutical preparations 
called spirit and salt of hartshorn, and Dippel’s animal oil. Occasion- 
ally the acetic, benzoic, and some other acids are formed by the ope- 
ration of heat on animal bodies, and these are found united to the am- 
monia; cyanogen and hydrocyanic acid also frequently occur. 
If the gas evolved during the decomposition of animal bodies be 
examined, it is generally inflammable, and consists of carburetted hy- 
drogen, often with a little sulphuretted and phosphuretted hydrogen ; 
carbonic oxide, carbonic acid, and nitrogen, are also sometimes detect- 
ed in it. 
The coal remaining in the retort is commonly very difficult of inci- 
neration, a circumstance depending upon the common salt and phos- 
phate of lime, which it usually contains, forming a glaze upon its sur- 
face which defends the carbon from the action of the air. Animal 
charcoal is also found to be more effectual in destroying colour and 
smell, than that obtained from vegetables. (387.) 
Nitrogen. 
Ammonia. 
Carburetted 
hydrogen. PROXIMATE PRINCIPALS OF ANIMALS. 
545 
1949. By the term putrefaction we mean the changes which dead) 
animal matter undergoes, and by which it is slowly resolved into new 
products. These changes require a due temperature, and the presence 
of moisture ; for below the freezing point of water, or when perfectly 
dry, it undergoes no alteration. 
During putrefaction the parts become soft and flabby, they change 
in colour, exhale a nauseous and disgusting odour, diminish consider- 
ably in weight, and afford several new products, some of which escape 
in a gaseous form, others run off- in a liquid state, and others are con- 
tained in the fatty, or earthy residuum. 
The presence of air, though not necessary to putrefaction, materi- 
ally accelerates it, and those gases which contain no oxygen, are very 
efficient in checking or altogether preventing the process. Carbonic 
acid also remarkably retards putrefaction ; and if boiled meat be care- 
fully confined in vessels containing that gas, it remains for a very long 
time unchanged, as seen in M Appert’s method of preserving meat. 
There are several substances which, by forming new combinations 
with animal matter, retard or prevent putrefaction, such as many of 
the saline and metallic compounds ; sugar, alcohol, volatile oils, acetic 
acid, and many other vegetable substances also stand in the list of anti- 
putrefactives, though their mode of operating is by no means under- 
stood. 
1950. The effluvia which arise from putrescent substances, and 
more especially those generated in certain putrid disorders, have a 
tendency to create peculiar diseases, or to give the living body a ten- 
dency to produce poisons analogous to themselves. An atmosphere 
thus tainted by infectious matter, may be rendered harmless by fumi- 
gation with the volatile acids, more especially the nitrous and the mu- 
riatic ; chlorine is also very effectual: the vapour of vinegar, though 
sometimes useful in covering a bad smell, is not to be relied on. It 
appears evident that the acid and chlorine act chemically upon the 
pernicious matter, and resolve it into innocuous principles. 
1951. When muscular flesh is immersed in a stream of running wa- 
ter, it is partially converted into a substance having many of the pro- 
perties of fat combined with a portion of ammonia. The same changes 
have been observed where large masses of putrefying animal matter 
have been heaped together, or where water has had Occasional access 
to it. Nitrate of ammonia is also sometimes formed under the same 
circumstances. 
1952. Instead of considering the proximate principles of animals 
under separate sections, as has been done in regard to vegetable bodies 
I shall make them known under the heads of those substances in which 
they occur, the principal of which are the following : 
Putrefaction. 
Antiseptics. 
X 
; Adipoure. 
1. Blood. Albumen. Colouring Matter. 
2. Milk. Sugar of Milk. 
3. Bile. Resin of Bile. 
4. Lymph. Mucus. Synovia, Pus, <^c. 
5. Urine Urea. Urinary Calculi. 
6. Skin. Membrane. 
7. Muscle. Ligament. Horn. Hair 
8. Fat. Spermaceti, fyc. 
9. Cerebral substance. 
10. Shell and Bone. SERUM Ob' THE BLOOP. 
Section II. Of the Blood. 
1953. In the higher orders of animals the blood is of a red colour, 
florid in the arteries, and dingy in the veins. The specific gravity of 
human blood is liable to some variation. I have found it as low as 
1.050 and as high as 1.070, but am unable to refer to any circum- 
stances which might be considered as the cause of this difference. 
When blood is drawn from its vessels in the living animal, it soon 
concretes into a jelly-like mass, which afterwards gradually separates 
into a fluid serum, of a pale straw colour, and a coagulated crassamen- 
turn, or cruor, which is red. The cause of this coagulation is quite 
unknown. 
1954. The specific gravity of the serum of the blood, is upon an ave- 
rage 1.030. It reddens the yellow of turmeric, and changes the blue 
of violets to green, a property derived from a portion of soda. At a 
temperature of 160°, it becomes a firm yellowish white coagulum, re- 
sembling in appearance and properties the coagulated white of egg, 
and, as the principle to which this property is owing is the same in 
both substances, it has been called albumen. Alcohol, and many of the 
acids, also occasion the coagulation of the serum of blood. 
100 parts of human serum contain between eight and nine parts of 
albumen, rather less than one part of carbonate of soda, and about the 
same quantity of common salt, the remaining 90 parts being water. 
These at least are the proportions which my own experiments lead me 
to believe correct; but the analysis is involved in so much difficulty 
that the results can only be considered as approximating to the truth ; 
indeed it is probable that the composition of the serum is liable to much 
variation. 
Dr. Marcet and Berzelius have each given an analysis of the serum 
of human blood ; the following are their results. (Medico-Chirurgical 
Transactions, Vol. ii. Annals of Philosophy, Vol. ii.): 
Marcet. 
Water 
- 900. 
Albumen 
Muriates of potassa and soda - - 
- 6.6 
Muco-extractive matter - - - - 
- 4.0 
Carbonate of soda 
1.65 
Sulphate of potassa 
- 0.35 
Earthy phosphates 
- 0.60 
1000.00 
Water 
905.0 
Albumen 
80.0 
Muriates of potassa and soda - - - 
6.0 
Lactate of soda, with animal matter - 
4.0 
Soda and phosphate of soda with ditto 
Loss - . : 
4.1 
0.9 
1000.0 
Berzelius. ALBUMEN. 
547 
1955. Albumen, which constitutes a leading ingredient in the serum, 
and which we shall presently find also in the cruor, is a very important 
animal principle, and is found in the greater number of animal fluids 
and solids. 
Liquid Albumen is soluble in water, and always contains a notable 
portion of soda, indicated by its action on vegetable colours. It is co- 
agulated by heat, acids, and alcohol, unless it be considerably diluted 
with water, in which case a portion separates in the form, of white 
flakes after some hours’ standing. Solution of corrosive sublimate, 
added to albumen very much diluted, produces a cloudiness, and hence 
it is a useful test of albumen. (Bostock, Nicholson’s Journal, xiv.) 
It is also instantly coagulated by Voltaic electricity; and if two plati- 
num wires connected with a small battery be immersed into a diluted 
albumen, it will cause a very rapid coagulation at the negative pole, 
and scarcely any effect at the positive pole. This circumstance induc- 
ed me to atribute the coagulation to the removal of the alcali, by alco- 
hol, and by acids ; but how heat operates is not very obvious, unless 
we be allowed to consider it as effecting a kind of decomposition of the 
liquid albumen. We might thus consider liquid albumen as a com- 
pound of albumen and soda dissolved in water : the effect of heat would 
then be to transfer the soda to the water, and thus occasion a coagula- 
tion ; and a solution of soda is always found oozing from coagulated 
serum, and has sometimes been called serosity ; in time it re-acts upon 
the coagulum, and dissolves a portion of it. 
1956. When albumen is dried in a moderate heat, it shrinks and be- 
comes brown and simi-transparent, resembling horn in appearance and 
properties. In this state it scarcely dissolves in boiling water, though 
it gradually softens ; it is not prone to decomposition ; it dissolves in 
the alcalis, a portion of ammonia being evolved and a saponaceous com- 
pound formed. Dilute nitric acid converts it into a substance having 
the properties of gelatine. (Hatchett, Phil. Trans., 1800.) 
By destructive distillation albumen furnishes a variety of products 
characterized by the presence of a large proportion of ammonia. Ac- 
cording to Gay-Lussac and Thenard, (Recherches Physieo-chymiques) its 
ultimate constituents are 
Carbon 
52.883 
Oxygen 
23.872 
Hydrogen 
7.540 
Nitrogen 
15.705 
100.000 
1957. When the coagulum of the blood is carefully washed under 
a small stream of water, the colouring matter is gradually dissolved, 
and washed out of it, and a white fibrous substance remains, which has 
been termed fibrina or coagulable lymph, but of which the chemical 
properties are those of albumen. 
It sometimes happens, when the blood is long in coagulating, as in 
certain inflammatory diseases, that a portion of this albumen is left 
without the colouring matter, forming what has been called the buffy 
coat of blood; in this case it is so tough as to admit of being removed 
from the coloured portion, and when dried, shrinks up, and appears 
exactly like horn. COLOURING HATTER OF THE BLOOD. 
Although the cause of the spontaneous coagulation of blood be un- 
known, the process consists in a portion of the albumen separating in 
a solid form along with the colouring matter, while another portion re- 
mains dissolved in the serum ; this effect is somewhat analogous to the 
crystallization of a saline solution, in which one portion of the salt se- 
parates, while another remains dissolved. 
1958. The colour of the blood has generally been referred to small 
globules of a red colour, which by the aid of the microscope may be 
discerned in it; and it was supposed that these globules are soluble in 
water. But it has been shown by Dr. Young, that this is not the case, 
and that the effect of water is to dissolve the colouring matter only, 
leaving the globule perfectly colourless ; in this state the globular parti- 
cles have the properties of albumen. The diameter of the globules in 
human blood varies from _ to yo °f an inch.-*—Remarks on Blood 
and Pus, in Dr. Young’s Medical Literature. 
The colouring matter of the blood can scarcely be obtained free 
from other substances. By stirring it during coagulation, a considera- 
ble portion is diffused through the serum from which it afterwards 
subsides. Vauquelin advises the digestion of the coagulum, drained of 
serum, in dilute sulphuric acid, at a temperature of 160°. The li- 
quid, filtered while hot, is to be evaporated to half its bulk, and near- 
ly saturated with ammonia; the colouring matter falls, and is to be 
washed and dried, (Annales de Chimie et Physique, Tom. i.) We must 
not, however, trust animal principles to these complex operations ; 
and there can I think be little doubt that the colouring principle has 
undergone some change in M. Vauquelin’s process. 
The chemical properties of the colouring matter of the blood show 
that it is a peculiar animal principle. It is soluble in cold water, and 
the solution, when boiled, deposits a brown sediment of altered colour- 
ing matter. Muriatic, dilute sulphuric, and several of the vegetable 
acids, and the caustic and carbonated alcalis, readily dissolve the co- 
louring matter, and form solutions of different tints of red, and of a 
peculiar greenish hue when viewed by transmitted light. Nitric acid 
instantly renders these solutions brown, and decomposes the red prin- 
ciple. These experiments, of which I have given a detailed account in 
the Philososophical Transactions for 1812, led me to regard the colour- 
ing matter of the blood as a distinct proximate principle of animal mat- 
ter, perfectly independent of the presence of iron, to which its pecu- 
liarities were at one time referred by MM. Fourcroy and Vauquelin ; 
and the latter of these celebrated chemists has more lately verified my 
conclusions in the above-quoted memoir. Berzelius, whose labours in 
animal chemistry are so extended and well known, has, however, ob- 
tained different results ; he finds the crassamentum of the blood to 
consist of 
Colouring matter .... 
Fibrin and albumen . . . 
. . 36 
100 
The colouring matter, when incinerated, affords a residue, consisting 
•f MILK, BUTtER, &C. 
Oxide of iron 
Subphosphate of iron 
Phosphate of lime with magnesia . . . 
6.0 
Lime 
Carbonic acid and loss 
. 16.5 
100.0 
The iron appears to be regarded by Berzelius as contributing to the 
red colour of the blood, (Thomson’s System, Vol. iv., p. 501.) a con- 
clusion which my own experiments, detailed in the paper already quot- 
ed, by no means warrant, and which is also at variance with the opi- 
nion of M. Vauquelin. 
1959. Besides the principles now enumerated, and which may be 
considered as essential to the blood, it often contains carbonic acid, 
which escapes when the blood is gently heated, or placed under the 
exhausted receiver of the air-pump. 
Experiments on the blood, in different diseases, have thrown no light 
whatever on their nature, nor have any material differences been found 
in the blood of the same animal at different periods, or in that of dif- 
ferent animals of the same class. 
Section III. Milk. 
1960. The chemical properties of this secretion differ somewhat in 
different animals. The milk of the cow has been most attentively ex- 
amined, and it has the following properties : 
It is nearly opaque; white, or slightly yellow; of an agreeable 
sweetish taste, and a peculiar smell. Its specific gravity varies from 
1018 to 1020. It boils at a temperature a little above that of water, 
and freezes at 32°. When allowed to remain a few hours at rest, 
a thick unctuous liquid collects upon its surface called cream; the 
colour of the remaining milk becomes bluish white and when heated 
to about 100° with a little rennet, it readily separates into a coagulum 
or curd, and a serum or whey. In this way the three principal consti- 
tuents of milk are separable from each other. 
1961. By the process of churning, cream is separated into butter, 
and butter-milk, the latter being the whey united to a portion of curd. 
According to Berzelius, 100 parts of cream, of the specific gravity of 
1024, consists of 
Butter 
Curd 
Whey 
92.0 
100.0 
Butter may be considered as an animal oil, containing a small portion 
of curd and whey. It liquefies at about 98°, and by this process the 
impurities are separated, and it remains a longer time without becom- 
ing rancid. 550 
SACLACTIC ACID. 
1962. The curd of milk has the leading properties of coagulated 
albumen, and, like that principle, is coagulable by alcohol and acids, 
and is also similarly affected by Voltaic electricity ; heat slowly pro- 
duces the same effect, and by boiling milk, the albumen separates in 
successive films. 
1963. Curd, in combination with various proportions of butter, 
constitutes the varieties of cheese; that containing the largest quantity 
of oil becomes semi-fluid when heated ; it is prone to decomposition, 
and a large quantity of ammonia is then formed in it; whereas bad 
cheese, which consists of little else than curd or albumen, shrinks and 
dries when heated, curling up like a piece of horn. 
1964 Whey is a transparent fluid of a pale yellow colour and a 
sweetish flavour ; by evaporation it affords a minute quantity of saline 
matter, and a considerable portion of sugar of milk. 
1965. Sugar of Milk may be obtained in white rhomboidal crystals, 
of a sweet taste, and soluble in seven parts of water at 60°, but inso- 
luble in alcohol. When exposed to heat, it affords nearly the same 
products as common sugar. It consists, according to Berzelius, when 
deprived of water, of 
Carbon 
Oxygen 
Hydrogen 
6.385 
100.000 
1966. When sugar of milk is treated with nitric acid, it affords a pe- 
culiar acid, similar to that above-mentioned, as obtained from gum 
(1549). To procure this acid, one part of powdered gum arabic may 
be digested in two of nitric acid, in a moderate heat; as soon as effer- 
vescence commences, set the flask in a cool place, and a quantity of 
white powder subsides, which is to be collected upon a filter, digested 
in dilute nitric acid to separate oxalate of lime, and subsequently puri- 
fied by boiling water, which deposits the inucic or saclactic acid on 
cooling. If sugar of milk be used instead of gum, it is obtained pure 
by the first operation. This acid is not crystallizable, and is sparingly 
soluble in water, requiring 60 parts at 212°, and is deposited as the 
solution cools, in the form of a white gritty powder, of a slightly acid 
taste. It combines with the metallic oxides, and forms a class of salts 
called saccholates. It consists, according to Berzelius, (Annals of Phi- 
losophy, Vol. v.) of 
Carbon ... - 
- - - 33.430 
Oxygen - - - - 
- - - 61.465 
Hydrogen - 
- - - 5.105 
100.000 
1967. The saccholates, or saclactatcs, have scarcely been examined. 
With ammonia, potassa, and soda, this acid forms crystallizable com- 
pounds, more soluble than the acid. The saclactates of lime, baryta, 
and strontia, are insoluble, as are those of silver, mercury, and lead. 
1968. When milk or whey are exposed to a temperature between 
60° and 80°, they undergo a spontaneous change, attended by the pro- 
duction of an acid, which was originally examined by Scheele, and has BILE. 
been termed lactic acid. Fourcroy and Vauquelin have shown reason 
to suspect its peculiar nature, and were led to regard it as identical with 
the acetic acid. Berzelius has more recently revived the opinion of 
Scheele, but I am induced from my own experiments to believe, that 
if it be not the acetic acid originally, it becomes so by combination 
with abase, and subsequent separation by sulphuric acid. 
1969. In some cases whey may be made to undergo vinous fermen- 
tation ; and the Tartars, it is said, prepare a kind of wine from the 
whey of mares’ milk, which they call Koumiss.—Edinburgh Phil. 
Trans., Vol. ii. 
Section IV. Bile. 
1970. This secretion is formed in the liver, from venous blood. If 
is an unctuous liquid, of a yellowish green colour, and its specific gra- 
vity is between 1020 and 1030. Its taste is intensely bitter, and it 
readily putrefies, exhaling a most nauseous odour. 
1971. When the bile of the ox is distilled, it affords about 90 per 
cent, of insipid water ; the residuum is brown, bitter, and maybe re- 
dissolved in water ; it affords traces of uncombined alcali, which ap- 
pears to be soda. The acids render bile turbid, and separate from it 
a substance which possesses many of the properties of albumen. It is 
likewise coagulated by alcohol, and upon filtering off the clear liquor 
and evaporating it, an inflammable fusible substance is obtained, of an 
intensely bitter flavour, combined with a portion of soda and common 
salt: this has been termed the resin of bile, and appears to be the 
principle which confers upon it its chief peculiarities. We should, 
therefore, conclude, as the result of these observations, that bile con- 
sists of water, albumen, soda, a bitter resin, and some minute portions 
of saline matter. 
1972. Thenard separated from bile a peculiar substance, which he 
has termed picromel; but the process by which he obtained it is so 
complex, that I think it doubtful whether it be a product or an educt. 
The same chemist has given the following table of the ingredients of 
ox-bile, but as this secretion is liable to considerable variation in ap- 
pearance and specific gravity, it is probable that little reliance can be 
placed in the accuracy of the numbers ([Traite de Chimie, Tom. iii., p 
456.) : 
Water 
- 700 
Resin 
- 15 
Picromel - 
- 60 
Yellow matter 
4 
Soda 
4 
Phosphate of soda 
2 
Muriates of soda and potassa - - 
3.5 
Sulphate of soda 
0.8 
Phosphate of lime and of magnesia 
1.2 
Oxide of iron 
1000. 552 
LYMPH ANB MUCU.S. 
1973. Biliary Calculi are of two kinds ; those which most common- 
ly occur, are soft, fusible, of a crystalline texture, and inflammable. 
They have generally been considered as closely resembling spermace- 
ti ; they are soluble in boiling alcohol, in ether, and difficultly in oil of 
turpentine. Chevreul, having remarked some peculiarities in this 
substance, is induced to regard it as a peculiar animal principle, and 
distinguishes it by the name of cholesterine. 
1974. Cholesterine is fusible at 280°, and on cooling concretes into 
a crystalline mass ; rapidly heated to about 400° it evaporates in dense 
smoke ; it is insoluble in water, and nearly so in cold alcohol; boiling 
alcohol dissolves about its weight. It is soluble in nitric acid ; but 
not convertible into soap by the alcalis. 
1975. The other kind of biliary calculus resembles inspissated bile 
in appearance, but differs from it in being insoluble in alcohol and 
water. It is often mixed with variable proportions of the former, con- 
stituting biliary calculi of intermediate characters. 
1976. The gall-stone of the ox is nearly insoluble in water and al- 
cohol, and appears to consist chiefly of the yellow matter of bile ; 
painters sometimes use it as a yellow pigment. 
Section V. Lymph, Mucus, Pus, &.c. 
1977. The liquid which lubricates the different cavities of the body, 
which is contained in the lymphatics, and which occasionally forms the 
chief contents of the thoracic duct, has been termed lymph. It is co- 
lourless, transparent, miscible in all proportions with water, does not 
affect vegetable blues, is not coagulated by acids or alcohol, but only 
rendered slightly turbid by the latter. It has the characters of a very 
weak solution of albumen. 
The fluid which collects in cases of dropsy and in vesications, is of 
a similar nature, but the proportion of albumen is liable to variation, 
and hence it is differently influenced by tests ; when very rapidly- 
thrown out from inflamed surfaces, it sometimes furnishes a coagulum, 
apparently as abundant as that of the serum of the blood. 
1978. The term mucus has sometimes been applied to these fluids* 
when they have undergone a certain degree of inspissation ; at other 
times, it has been used to designate a very alcaline albuminous fluid. 
Dr. Bostock has pointed out some circumstances in which mucus dif- 
fers from liquid albumen, and has proposed subacetate of lead as a test 
for its presence. (Nicholson’s Journal, Vol. xi.) But that salt is so 
easily decomposed by many vegetable and animal substances, as to ren- 
der it of doubtful efficacy for this purpose. 
1979. Saliva consists, according to Dr. Bostock, (Nicholson’s Jour- 
nal, Vol. xiv.) of 
Water 
Coagulated albumen . . 
Mucus 
Saline s'ubstances . . . . 
100 VRINE. 
553 
I found that it was copiously coagulable by the action of Voltaic 
electricity, and was hence induced to consider the mucus as a peculiar 
albuminous combination, not coagulable by the usual means.—Phil. 
Trans., 1809. 
1980. The Pancreatic juice has not been minutely examined, but 
from the experiments of I)r. Fordyce, it would appear to differ little 
from saliva. 
1981. Tears contain a small portion of albumen combined with soda, 
muriate of soda, and water. There are also small portions of other 
salts. 
1982. The humours of the Eye. The aqueous humour is composed 
of water holding a minute quantity of albumen and saline matter in so- 
lution ; the crystalline lens also contains more than half its weight of 
water, the remainder being an albuminous substance with traces of 
muriates. 
1983. Synovia is the fluid which lubricates the surfaces of joints. 
It contains, according to Mr. Hatchett, {Phil. Trans., 1799.) a small 
portion of phosphate of lime, and of phosphate of soda and ammonia; 
the animal principle appeared to be albumen. 
1984. Pus is a term applied to a variety of secretions from abcesses 
and ulcerated surfaces. When it indicates a healing sore, it has been 
called healthy pus, and has the following properties. It has the consis- 
tency of cream, a yellowish colour, and exhibits, under the microscope, 
the appearance of globules diffused through a fluid. (Home, On Ulcers, 
2 Edit., p. 13.) Its specific gravity is about 1.030. It does not affect 
vegetable colours till it has been some time exposed to air, when it 
becomes slightly sour ; it does not easily mix with water, alcohol, or 
dilute acids.—See Dr. Pearson’s Experiments on Pus, Nicholson’s 
Journal, xxx. 
Section VI. Urine, Urinary Calculi, &c. 
1985. This secretion presents, perhaps, greater difficulties to the 
analytical chemist, than any other animal product ; it is extremely 
complex, and subject to constant change in the proportions of its com- 
ponents, and in disease several new substances make their appearance. 
The chemical history of the urine is of the utmost importance to 
the medical practitioner ; it teaches the nature of the substances 
which occasionally predominate, so as to constitute gravel and calculi; 
and shows the means of influencing and modifying its composition. 
The general characters of the urine are too well known to need 
description. Its specific gravity is of course liable to much variation 
even in the healthy state, fluctuating between 1005 and 1040. The 
average is about 1020. 
1986. The substances that are always found in urine are, according 
to my own experiments, the following : 
1. Water. 
2. Carbonic acid. 
3. Phosphoric acid. 
4. Uric acid. 
6. Phosphate of lime. 
6. Phosphate of ammonia. 
7. Phosphate of soda. 
8. Phosphate of magnesia. 
9. Common salt. 
10. Sulphate of soda. 
11. Albumen. 
12. Urea. 554 
1987. The existence of free acid in recently voided urine is easily 
demonstrated by its property of reddening vegetable blues, and it per- 
forms the important office of retaining some of the difficulty soluble 
salts in permanent solution ; so that whenever this natural acidity is 
diminished, the urine has a tendency to deposit the earthy phosphates. 
1988. The presence of carbonic acid may be shown by placing urine 
under the receiver of the air-pump ; during exhaustion it escapes, 
sometimes copiously, but at other times in minute quantities only. 
1989. The free Phosphoric acid may be shown by the addition of 
carbonate of lime, a portion of which is converted into phosphate of 
lime. 
1990. Uric acid is one of the peculiar characteristics of the urine ; 
its presence may be shown by evaporating urine to half its bulk, which 
produces a precipitate consisting of phosphate of lime and uric acid ; 
the former may be dissolved by dilute muriatic acid, which leaves the 
latter in the form of a reddish powder. This acid has been very ably 
examined by Dr. Henry, who made it the subject of a thesis publish- 
ed in 1807 : Dr. Prout has also given much valuable information in 
relation to it. 
Uric acid, called sometimes lithic acid, as constituting the principal 
ingredient in certain urinary calculi, may be abundantly obtained by 
digesting such calculi (2005) in caustic potassa, filtering the solution, 
and adding excess of muriatic acid, which causes a precipitate of uric 
acid, which is to be washed with warm water, and dried. 
Uric acid thus obtained, is a grey powder, of scarcely any taste, and 
requiring, according to Dr. Henry, 1720 parts of water at 60°, and 
1150 parts at 212° for solution. It reddens infusion of litmus, and 
readily dissolves in caustic potassa, and soda ; it is sparingly soluble in 
ammonia, and insoluble in the alcaline carbonates. 
According to Dr. Prout, uric acid requires at least 10000 parts of 
Water at 60° for its solution, but urate of ammonia requires only about 
480 times its weight at the same temperature, and affords a precipitate 
of uric acid, on the addition of any other acid ; for these, among other 
reasons, Dr. Prout regards urate of ammonia, and not pure uric acid, 
as existing in urine. 
1991. Uric acid dissolves in nitric acid, and upon evaporation a re- 
siduum of a fine red tint is obtained, which is peculiar to this com- 
bination, and which Dr. Prout has lately shown to possess distinct acid 
properties; he has called it purpuric acid.—Phil. Trans. 1818. 
1992. When uric acid is submitted to destructive distillation, it af- 
fords carbonate of ammonia, and a peculiar compound, which sub- 
limes in crystals, and which, according to Dr. Henry, consists of a 
peculiar acid united to ammonia ; a quantity of charcoal remains in the 
retort. Its ultimate constituents, according to Dr. Prout, are. 
URIC ACID. 
1 proportional of nitrogen 
14 
2 
carbon 6X2 = 
12 
* 
oxygen 
- 8 
1 
hydrogen 
■ 1 
35 
1993. The urates have principally been examined by Dr. Henry, 
and an account of many of them is given in bis Thesis above quoted. UREA. 
555 
1994. Phosphate of Lime may be precipitated from urine by the ad- 
dition of ammonia ; its relative quantity is liable to much fluctuation ; 
sometimes it becomes so great as to be deposited as the urine cools, 
constituting what has been termed white sand. 
1995. The Phosphates of Ammonia, of Soda, and of Magnesia, and 
common Salt, constitute the principal crystallizable salts contained in 
the urine ; the first of these is probably in great part produced during 
evaporation, for the saline mass obtained by inspissating urine is no 
longer acid ; the carbonic having escaped, and the phosphoric being sa- 
turated by ammonia. The microcosmic salt, or fusible salt of urine, 
of the old chemists, is chiefly phosphate of ammonia with a little phos- 
phate of soda, or perhaps a triple ammonia-phosphate of soda (598). 
199G. The Amrnoniacd-magnesian Phosphate (692) is a common, 
and almost constant ingredient in the urine. It forms a part of the 
white sand voided in certain calculous affections, and is sometimes 
formed in a film upon the surface of the urine, having been held in so- 
lution by carbonic acid, and being deposited as that gas escapes. 
1997. The existence of sulphuric acid, probably combined with 
soda, and perhaps also with potassa, may be detected in urine by the ad- 
dition of nitrate of baryta, which occasions a precipitate of sulphate of 
baryta. 
As urine blackens silver, it has been said to contain sulphur; but 
this is not the case with recent urine, and when it becomes slightly pu- 
trid it evolves a little sulphuretted hydrogen. 
1998. The existence of albuminous matter in urine is sometimes 
easily demonstrated ; at others, the secretion seems not to contain it. 
It has been said, by Mr. Cruikshank, that the urine in some dropsical 
cases contains so much albumen as to be coagulable by heat, (Phil. 
Mag. Vol. ii.) but if that ever be the case, the secretion could hardly 
be called urine. It seems questionable whether the albumen of urine 
should not sometimes be regarded as derived from the mucous secretion 
of the bladder. Dr. Prout, in his Inquiry into the Nature and Treat- 
ment of Gravel, &c., has described some cases of albuminous urine, and 
has adverted to its method of cure. 
1999. Urea is the principle which confers upon urine its chief pe- 
culiarities. It may be obtained by slowly evaporating urine to the con- 
sistency of syrup ; on cooling it concretes into a saline mass, which, 
by digestion in alcohol, furnishes urea. By carefully distilling off the 
alcohol, the urea remains in the form of a brown crystallized mass, 
which, by purification, furnishes colourless prismatic crystals. 
Other processes have been given for obtaining urea, which are, I 
think, objectionable, on account of their complexity; indeed it is 
doubtful whether, by the action of heat and alcohol, as above describ- 
ed, it is not considerably altered. 
Urea is very soluble ; water, at 60°, takes up about its own weight, 
and boiling water appears to dissolve it in any quantity, and without al- 
teration : boiling alcohol takes up its own weight, and on cooling the 
urea separates in crystals. Sulphuric ether scarcely dissolves an ap- 
pretiable portion. Nitric acid produces a crystalline precipitate in the 
aqueous solution of urea, consisting of the two substances according to 
Dr. Prout, in the following proportions : 556 
DISORDERS OF THE URINE. 
Nitric acid - - - - 
Urea 
47.37 
52.63 
100.00 
A very similar compound may also be produced with oxalic acid. 
The fixed alcalis decompose urea, and occasion the evolution of am- 
monia and some other products. It is to this substance that the co- 
pious produciion of volatile alcali, during the destructive distillation of 
urine, is referable ; and the ammonia which is found in combination 
with the acids, in putrid urine, is derived from the same source. 
Urea combines with most of the metallic oxides ; with oxide of sil- 
ver the compound is grey, and it decomposes with detonation, when 
heated. 
According to Dr. Prout’s analysis (Henry’s Elements, Vol. ii. p. 
327,) urea consists of 
Oxygen - - 
- 26 66 = 1 proportional 
8 
Nitrogen - 
- 46,66 = 1 
55 
14 
Carbon - - 
- 19.99 = 1 
55 
6 
Hydrogen * 
- 6.66 = 2 
5 > 
2 
30 
In some diseased states of the urine there is a morbid excess of 
urea, which may be detected by putting a little of the urine into a 
watch-glass, and carefully adding an equal quantity of nitric acid, in 
such a manner that the acid shall subside to the lower part of the 
glass ; if spontaneous crystallization take place, it indicates excess of 
urea—Prout on Gravel, &c., p. 10. 
2000. Such are the properties of the principal ingredients in hu- 
man urine, to which several others have been added by different che- 
mists ; but as their existence is only occasional, and often, I think, 
doubtful, I have hesitated to give them a place among the regular con- 
stituents of healthy urine. I now subjoin Berzelius’ statement of the 
average composition of human urine.—Thomson’s Annals, Vol. ii. 
423. 
Water - -- -- 
933.00 
Urea 
30.10 
Sulphate of potassa 
3.71 
Sulphate of soda 
3.16 
Phosphate of soda 
2.94 
Muriate of soda 
4.45 
Phosphate of ammonia 
1.65 
Muriate of ammonia 
Free lactic acid 
1.50 
Lactate of ammonia 
Animal matter soluble in alcohol - - - 
Urea not separable from the preceding - 
V 17.14 
Earthy phosphates with a trace of fluate of, 
lime 1 
| 1.00 
Uric acid - 
1.00 
Mucus of the bladder ------ 
0.32 
Silica - - 
0.03 
1000.00 URINARY CALCULI. 
557 
2001. The urine suffers some very remarkable changes in certain 
diseases, which have been but superficially inquired into by chemists. 
In cases of injury of the spine, affecting the nerves that supply the 
kidneys, the urine is always turbid, and often alcaline ; and there is a 
considerable tendency in these cases to form calculi. 
In the disease called diabetes, the urine is not only secreted in ex- 
cress, but often contains a substance of a sweet taste, having the proper- 
ties of sugar, and its specific gravity is considerably above the healthy 
standard (Henry on Diabetic Urine. Medico-Chirurgical Trans , Vol. 
ii. p. 118.) The following Table, constructed by Dr. Henry, shows 
the quantity of solid extract in a wine pint of urine, of different speci- 
fic gravities, from 1020 to 1050. In the experiments which furnish- 
ed the data of this table, the urine was evaporated by a steam heat till 
it ceased to lose weight, and left an extract which became solid on cool- 
ing.—Prout on Gravel, p. 62. 
Sp. gr. compared with 
1000 pts. of water at 60°. 
Quantity of Solid extract 
in a wine pint. 
Quantity of Solid extract in a 
Wine Pint, in 
grs. 
o z. 
dr. 
scr 
grs. 
1020 
382.4 
0 
6 
l 
2 
1021 
401.6 
0 
6 
2 
, 1 
1022 
420.8 
0 
7 
0 
0 
1023 
440.0 
0 
7 
1 
0 
1024 
459.2 
0 
7 
1 
19 
1025 
478-4 
0 
7 
2 
18 
1026 
497.6 
1 
0 
0 
17 
1027 
516.8 
1 
0 
1 
16 
1028 
536.0 
1 
0 
2 
16 
1029 
555.2 
1 
1 
0 
15 
1030 
574.4 
1 
1 
1 
14 
1031 
593 6 
1 
1 
2 
13 
1032 
612.8 
1 
2 
0 
12 
1033 
632.0 
1 
2 
1 
12 
1034 
651.2 
1 
2 
2 
11 
1035 
670 4 
1 
3 
0 
10 
1036 
689-6 
1 
3 
1 
9 
1037 
708-8 
1 
3 
2 
8 
1038 
728-0 
1 
4 
0 
8 
1039 
747-2 
1 
4 
1 
7 
1040 
766.4 
1 
4 
2 
6 
1041 
785.6 
1 
5 
0 
5 
1042 
804 8 
1 
5 
1 
4 
1043 
824.0 
1 
5 
2 
3 
1044 
843.2 
1 
6 
0 
3 
1045 
862.4 
1 
6 
1 
2 
1046 
881.6 
1 
6 
2 
1 
1047 
900.8 
1 
7 
0 
0 
1048 
920.0 
1 
7 
1 
0 
1049 
939.2 
1 
7 
1 
19 
1050 
958.4 
1 
7 
2 
18 URINARY CALCULI. 
2002. The urine of graminivorous animals differs considerably from 
that of the human subject. Carbonates, muriates, and phosphates, 
are the leading ingredients ; it also contains urea, but not uric acid ; 
potassa is usually the predominating alcali. In the Phil Trans, for 
1808, I have given an account of the composition of several species 
of urine, and in that of the camel I detected a small portion of uric 
acid : but as the animal was diseased, its presence was probably acci- 
dental, more especially as it has not been found by other chemists. 
In the urine of the snake, and of most birds that feed upon fish and 
animal matter, uric acid is the leading ingredient. It is also abundant 
in the excrement of the parrot, and of other birds who feed upon ve- 
getables only.—J. Davy, Phil. Trans. 1821. 
2003. It frequently happens, from a variety of causes, that certain 
ingredients of human urine are secreted in excess, and deposited in a 
solid form, constituting sand, or gravel and calculi. 
Sand is either white or red; the former consists of phosphate of 
lime, and ammoniaco-magnesian phosphate, either separate or mixed, 
and the latter is chiefly uric acid. The former deposition is prevent- 
ed by the use of acids, and the latter by alcalis and the alcaline earths. 
The modes of exhibiting these remedies, and the effects which they 
produce, I have described in a paper printed in the Quarterly Journal 
of Science and Arts, Vol. vi. 
2004. Urinary calculi are, for the most part, composed of materials 
that exist at all times in the urine, though there are a few substances 
that only make their occasional appearance in them. The follow ing 
are their component ingredients : 
1. Uric acid. 
2. Urate of ammonia. 
3. Phosphate of lime. 
4. Ammonio-magnesian phosphate. 
5. Oxalate of lime. 
6. Carbonate of lime. 
7. Cystic oxide. 
2005. The calculi composed of uric acid, of which the chemical 
properties have already been described (1990), are of a brown or 
fawn-colour ; and, when cut through, appear of a more or less dis- 
tinctly laminated texture. Their surface is generally smooth, or near- 
ly so, being sometimes slightly tuberculated. Before the blow-pipe 
this calculus blackens, and gives out a peculiar ammoniacal odour, 
leaving a minute portion of white ash : it is soluble in solution of pure 
potassa, and heated with a little nitric acid, affords the fine pink com- 
pound, above-mentioned (1991). 
2006. Phosphate of lime calculus is of a pale brown, or grey co- 
lour, smooth, and made up of regular and easily separable laminae. It 
is easily soluble in muriatic acid and precipitated by pure ammonia, 
and does not fuse before the blow-pipe. Calculi from Ike prostate 
gland, are always composed of phosphate of lime. 
2007. The ammonio-magnesian, or triple calculus, is generally 
white, or pale grey, and the surface often presents minute crystals ; its 
texture is generally compact, and often somewhat hard and translucent; 
heated violently by the blow-pipe, it exhales ammonia, and leaves URINARY CALCULI. 
phosphate of magnesia. It is more easily soluble than the preceding, 
and oxalate of ammonia forms no precipitate in its muriatic solution. 
200b. It frequently happens that calculi consist of a mixture of the 
two last-mentioned substances, in which case they melt before the blow- 
pipe, and are hence termed fusible calculi. They are white or near- 
ly so, and softer than the separate substances, often resembling chalk 
in appearance. They are easily soluble in muriatic acid, and if oxa- 
late of ammonia be added to their solution, the lime is precipitated in 
the state of oxalate. 
2009. Oxalate of lime forms calculi, the exterior colour of which is 
generally dark brown, or reddish ; they are commonly rough, or tu- 
berculated upon the surface, and have hence been called mulberry 
calculi. Before the blow-pipe they blacken and swell, leaving a white 
infusible residue, which is easily recognised as quicklime (1736). 
Small oxalate of lime calculi are, however, sometimes perfectly smooth 
upon the surface, and much resemble a hempseed in appearance. 
2010. Urate of ammonia I admit among urinary calculi, upon the 
authority of Dr. Prout, my own experiments having formerly induced 
me to doubt its existence {Phil. Trans. 1808). Its surface is some- 
times smooth, sometimes tuberculated ; it is made up of concentric 
layers, and its fracture is fine earthy, resembling that of compact lime- 
stone ; it is generally of a small size, and rather uncommon, though it 
often occurs mixed with uric acid. It usually decrepitates before the 
blow-pipe, is more soluble than the uric calculus, evolves ammonia 
when heated with solution of potassa, and is readily soluble in the al- 
caline carbonates, which pure uric acid is not. 
2011. Dr. Prout and Mr. Smith {Med. et Chir. Trans. xi. 14.) have 
described calculi composed almost entirely of carbonate of lime, but 
this species is exceedingly rare, and among several hundred calculi 
which I have examined, I never met with it from the human bladder. 
2012. Cystic oxide is a peculiar animal substance ; the calculi com- 
posed of it, which are rare, are in appearance most like those of the 
ammonio-magnesian phosphate. They are soft, and when burned by 
the blow-pipe, exhale a peculiar foetid odour. They are soluble in 
nitric, sulphuric, muriatic, phosphoric, and oxalic acids, and also in 
alcaline solutions. 
2013. The substances which have been described, with the excep- 
tion of cystic oxide, are sometimes intimately blended in calculi; some- 
times they form alternating layers ; and in a few cases four distinct 
layers have been observed, the nucleus being uric, upon which the 
oxalate, and phosphate of lime, and the triple phosphate, are distinctly 
and separately arranged. 
2014. Dr. Marcet has described a calculus composed of a peculiar 
animal matter, which he calls Xanthie Oxide, from its property of giv- 
ing a yellow colour when acted on by nitric acid : he has also announc- 
ed the existence of calculus composed o£ Jibrine.—Essay on Calculous 
Disorders, 2d edit. p. 103. 
2015. These are the principal chemical facts belonging to the histo- 
ry of urinary calculi. In Dr. Wollaston’s valuable papers upon this 
subject {Phil. Trans. 1797 and 1810,) much additional information will 
be found. In the same work (1806, 1808, and 1810,) I have given 
some account of their peculiarities, depending upon their situation, and 
have also discussed the operation of solvents, a subject which I have GELATINE. 
taken up more in detail in the Quarterly Journal of Science and the Arts, 
Vol. viii. Dr. Marcct and Dr. Frout have also published excellent dis- 
sertations on Calculous Disorders, containing all that is most import- 
ant upon the fiubject. 
Section VII. Cutis, or Skin; Membrane, &c. 
2016. The skin of animals consists of an exterior albuminous cover- 
ing, or cuticle, under which is a thin stratum of a peculiar substance, 
called by anatomists rcte mucosum, and which lies immediately upon 
the cutis, or true skin, of which the principal component is gelatine. 
2017. The following are the chemical properties of pure gelatine. 
It is colourless, semi-transparent, and nearly tasteless. It is softened 
by long-continued immersion in cold water : in hot water it readily dis- 
solves, and forms a solution of as lightly milky appearance, which, if 
sufficiently concentrated, concretes on cooling into the tremulous mass 
usually called jelly, and which is easily soluble in cold water; when 
dried in a gentle heat it acquires its original appearance, and is as so- 
luble as before. When dry, gelatine undergoes no change, but its 
solution soon becomes mouldy and putrescent. Submitted to the action 
of heat it affords the usual products of animal substances.—Hatchett. 
Philos. Transact. Vol. xc. 
It is readily soluble in diluted acids and alcaline solutions, and forms 
no soap with the latter. Its aqueous solution is not affected by solu- 
tion of corrosive sublimate, and few of the metallic salts occasion any 
precipitate in it. Chlorine passed through its solution, occasions a 
white elastic matter to separate, which is not soluble in water, and 
which in some properties resembles albumen. It is insoluble in alco- 
hol and ether. Solution of tannin occasions a white precipitate in so- 
lution of gelatine; and hence, vegetable astringents such as galls or 
catechu, are generally employed as tests for its presence, But as tan- 
nin precipitates albumen, it cannot be relied on as an unequivocal test, 
unless we previously ascertain the non-existence of albumen by cor- 
rosive sublimate.—Bostock. Nicholson’s Journal, xiv. and xxi. 
Mr. E, Davy recommends sulphate of platinum as a very delicate 
test of gelatine, with which it forms a brown insoluble compound, in 
solutions too weak to be affected by vegetable astringents.—Phil. 
Trans. 1820, p. 119. 
2018. The action of sulphuric acid upon gelatine has been investi- 
gated by M. Braconnot. Twelve parts of powdered glue and 24 of 
sulphuric acid, were left together for 24 hours ; about 60 parts of 
water were then added, and the whole boiled for 5 hours, adding water 
at intervals ; the solution was then saturated with chalk, filtered, and 
suffered to evaporate spontaneously. In a month crystals were depo- 
sited, which, being purified by solution and a second crystallization, 
much resembled sugar of milk, though they differ from that substance 
in affording a peculiar acid, calle-d by M. Braconnot Nitro-saccharine 
acid, when acted upon by nitric acid.—Ann. de Chimie et Phrjs., xiii. 
2019. The different kinds of gelatine differ considerably in viscidity. MEMBRANES. 
561 
Mr Hatchett has remarked that the gelatine obtained from skins pos- 
sesses a degree of viscidity inversely as their softness or flexibility ; 
the most adhesive kinds of gelatine, too, are less easily soluble in water 
than those which are less tenacious. The principal varieties of gela- 
tine in common use are, 
a. Glue, which is prepared from the clippings of hides, hoofs, 
obtained at the tan-yard ; these are first washed in lime-water, and after- 
wards boiled and skimmed; the whole is then strained through baskets, 
and gently evaporated to a due consistency ; afterwards it is cooled in 
wooden moulds, cut into slices, and dried upon coarse net-work. 
Good glue is of a semi-transparent and deep brown colour, and free 
from clouds and spots. When used it should be broken into pieces, and 
steeped for about 24 hours in cold water, by which it softens and 
swells ; the soaked pieces may then be melted over a gentle fire, or 
in a water-bath, and in that state applied to the wood by a stiff brush. 
Glue will not harden in a freezing temperature, the stiffening depend- 
ing on the evaporation of its superfluous water. 
b. Size is less adhesive than glue, and is obtained from parchment 
shavings, fish-skin, and several animal membranes. It is employed by 
bookbinders, paper-hangers, and painters in distemper, and is some- 
times mixed with flour, gum, 4*c. 
c. Isinglass is prepared from certain parts of the entrails of several 
fish ; the best is derived from the sturgeon, and is almost exclusively 
prepared in Russia. It should be free from taste and smell, and entire- 
ly soluble in warm water, which is seldom the case, in consequence of 
the presence of some albuminous parts. When the jelly of isinglass 
is concentrated by evaporation and carefully dried, it forms a very 
choice kind of glue.—Aikin’s Dictionary, Art. Gelatine. 
2020. Leather is a compound of gelatine and vegetable astringent 
matter, formed by steeping the skins of animals in the infusions of cer- 
tain barks. The skins are previously prepared by soaking in lime- 
water, which renders the cuticle and hair easily separable, and are 
afterwards softened by allowing them to enter into a degree of putre- 
faction. In this state they are submitted to the action of infusion of 
oak-bark, or other astringent vegetable matter (1602), the strength of 
which is gradually increased until a complete combination has taken 
place, which is known by the leather being of an uniform brown colour 
throughout; whereas, in imperfectly tanned leather a white streak is 
perceptible in the centre. 
Tawed leather is made by impregnating the skin duly prepared, with 
a solution of alum and common salt; it is afterwards trodden in a mix- 
ture of yolk of eggs and water. 
Curried leather is made by besmearing the skin, or leather, while yet 
moist, Avith common oil, which, as the humidity evaporates, penetrates 
into the pores of the skin, giving it a peculiar suppleness, and making 
it, to a considerable extent, water-proof. As familiar examples of these 
processes, the thick sole-leather for shoes and boots is tanned; the up- 
per-leather is tanned and curried; the white leather for gloves is 
tawed; and fine Turkey-leather is tawed, and afterwards slightly tan- 
ned.—Aikin’s Dictionary, Art. Leather. 
2021. The different membranes of the bod}r, and the tendons, are 
chiefly composed of gelatine, for by long digestion in warm water they 
gradually soften, and become ultimately almost perfectly soluble-. FAT, SPERMACETI, &fC. 
Section VIII. Muse e, Ligaments, Horn, Hair, fyc. 
2022. When the muscular parts of animals are washed repeatedly 
in cold water, the fibrous matter which remains consists chiefly of al- 
bumen, and is in its chemical properties analogous to the clot of blood 
(1957). Muscles also yield a portion of gelatine ; and the flesh of beef, 
and some other parts of animals, afford a peculiar substance of an aro- 
matic flavour, called by Thenard, osmazome. 
2023. 30 parts of beef fibre, acted on by as much sulphuric acid, yield- 
ed M. Braconnot, a portion of fat, and on diluting the acid mixture, and 
saturating with chalk, filtering, and evaporating, a substance, tasting like 
osmazome was obtained, which was often boiled in different portions of 
alcohol : the alcoholic solutions, on cooling, deposited a peculiar white 
pulverulent matter, which Braconnot calls leucine, and which acted 
upon by nitric acid affords a crystallizable nitroleucic acid.—Annales dt 
Chimie et Phys., xiii. p. 118. 
2024. Ligaments, horn, nail, and feathers, consist principally of al- 
bumen. 
2025. Hair consists principally of a substance, having the proper- 
ties of coagulated albumen. It also contains gelatine, and the soft 
kinds of hair yield it more readily than those which are harsh, strong, 
and elastic.—Hatchett. Phil. Trans. 1800. 
Vauquelin discovered in hair two kinds of oil; the one white, and 
existing in all hair ; the other coloured, yellow from red hair, and dark 
coloured when obtained from dark hair. Black hair also contain# 
iron and sulphur. He supposes that where hair has become suddenly 
gray, the effect is produced by the evolution of acid matter, which 
has destroyed the colour of the oil. 
2026. Feathers, quills, and wool, are also possessed of the proper- 
ties of albumen, and appear to contain no gelatine. 
Section IX. Fat, Spermaceti, &c. 
2027. The fat of animals, when freed by fusion or pressure from 
cellular membrane, is of various degrees of consistency, as seen in 
tallow, lard, and oil. When pure, it has little taste or smell, but it 
acquires both by keeping, and becomes rancid and slightly sour. The 
softer varieties fuse at about 90°, and.the harder at 120°. Decomposed 
at a red heat, they afford abundance of olefiant gas, and a small portion 
of charcoal; products analogous to those of vegetable oil. (741.) 
When burned, they produce water and carbonic acid, containing the 
same ultimate elements, in the same proportions as vegetable oils. 
(1634.) 
They also produce soaps by combination with alcalis. 
Nitric acid, heated in small quantity with any of the fatty substances, 
renders them harder, and considerably increases their solubility in al- 
cohol. Among the vegetable oils this change is most remarkably pro- 
duced upon cocoa-nut, and castor-oils, the latter becoming converted SPERMACETI. 
563 
into a solid matter, which, when cleansed of adhering acid by wash- 
ing, resembles soft wax. 
2028. The experiments of Braconnot and Chevreul, already quoted, 
(1628) have shown that the different kinds of oil and fat contain two 
substances, to which they have given the names stearine and elaine, 
the former solid, the latter liquid at common temperatures. The fol- 
lowing table shows their relative proportions in different fats and oils : 
Elaine. 
Stearine. 
Butter, made in summer 
60 . . 
. . . 40 
Ditto, winter 
37 . . 
. . . 63 
Hogs’-lard 
62 . . 
. . . 38 
Beef-marrow 
24 . . 
. . . 76 
Mutton ditto 
74 . . 
. . . 26 
Goose-fat 
68 . . 
. . . 32 
Ducks’-fat 
72 . . 
. . . 28 
Turkey’s-fat 
74 . . , 
. . . 26 
Olive-oil 
72 . . , 
. . . 28 
Almond-oil 
76 . . . 
. . 24 
These principles may be obtained by boiling hogs’-lard in alcohol ; 
the fluid, on cooling, deposits a crystalline matter, which is to be puri- 
fied by a second solution and crystallization ; it i9 then pure stearine, 
white, brittle, tasteless, and inodorous ; it fuses at a little below 120°, 
and forms soap with alcalis. 
When the alcohol which has deposited the whole of the stearine is 
distilled, an oily liquid remains, which is elaine. It is fluid at 58° ; it 
generally is of a yellow colour, and is convertible into soap. 
2029. When soap composed of hogs’-lard and potassa, is put into 
water, a portion only is dissolved the remainder consists of white 
scales, composed of the alcali united to a peculiar acid, called by Chev- 
reul, from its pearly appearance, margaritic acid, and separable from 
the above combination by muriatic acid. 
It is insoluble in water, tasteless, fusible at 134°, and crystallizes on 
cooling in brilliant white needles. It is soluble in alcohol. It unites 
with potassa in two proportions, the one compound containing 100 acid 
4* 8.80 potassa; the other, 100 acid -j- 17.77 potassa. These com- 
pounds have been termed margarates of potassa. 
2030. The portion of the hogs’-lard soap soluble in water, consists 
of another peculiar substance united to potassa, which Chevreul has 
called oleic acid. It may be obtained from its solution by tartaric acid, 
which causes it to separate in the form of an oily matter, that is to be 
again united to potassa, and separated as before. This substance soli- 
difies at about 40°, and it forms compounds, called oleates. It appears 
probable that, by the action of alcalis, the stearine is converted into 
what Chevreul has termed margaric acid, and the elaine into oleic acid. 
Annales de Chimie, xciv. 
2031. By mixing 1 volume of carbonic acid with 10 of carburetted 
hydrogen, and 30 of hydrogen, and passing the mixture through a red- 
hot porcelain tube. Berard is said to have produced a substance in 
small white crystals, having many of the properties of fat.—Thom- 
son’s Annals, xii. 
2032. Spermaceti or Cctine is a peculiar matter, which concretes 564 
from the oil of the spermaceti whale. It fuses at 112°, and at higher 
temperatures is volatile, but if repeatedly distilled it loses its solid 
form, and becomes a liquid oil. It is soluble in boiling alcohol, and 
abundantly so in ether. It forms a soap with potassa, which yields, on 
decomposition, a substance called by Chevreul, cetic acid.—Annales de 
Chimie, xcv. 
2033. In the yolk of eggs there is a considerable quantity of oily 
matter, which may be obtained by pressure after boiling ; it is yellow 
and tasteless. 
2034. Ambergris, which is a concretion from the intestines of the 
spermaceti whale, also contains a considerable portion of fatty matter, 
amounting in some specimens to 60 per cent. It is only found in the 
unhealthy animal.—Home’s Lectures on Comparative Anatomy, Vol. i., 
p. 470. 
2035. The brain of animals, when boiled in alcohol, furnishes a 
peculiar fatty matter, which the solution deposits as it cools, in bril- 
liant scales. It requires a higher temperature than that of boiling 
water for its fusion, and appears in many respects analogous to choles- 
terine. (1974.) The same substance is often seen in the alcohol em- 
ployed to preserve anatomical preparations of the brain and nerves. 
shell and bone. 
Section X. Cerebral Substance. 
2036. According to Vauquelin, the cerebral substance consists of 
Water 
White fatty matter 
4.53 
Red fatty matter 
Albumen 
Osmazome 
. . 1.12 
Phosphorus 
Acids, salts, and sulphur. . . 
. . 5.15 
100 
The pulp of nerves seems to be of a similar nature.—Thomson’s 
System, Vol iv., p. 482. 
Section XI. Shell and Bone. 
2037. We are indebted to Mr. Hatchett for two excellent disserta- 
tions on the chemical properties of these parts of animals, published 
in the Philosophical Transactions for 1799 and 1800. 
He has divided shells into two classes; the texture of the first is 
compact, brittle, and resembling porcelain ; their surface is smooth, ZOOPHYTES, 
and they are often beautifully variegated. When exposed to a red 
heat they crackle, and lose the colour of their enamelled surface, 
emitting scarcely any smoke or smell. They dissolve in dilute muria- 
tic acid with copious effervescence, and form a transparent solution, in 
which neither pure ammonia nor acetate of lead produce any precipi- 
tate, but carbonate of ammonia throws down carbonate of lime. 
Hence these, which are called porcellaneous shells, may be considered 
as composed of carbonate of lime, united to a very small portion of 
gelatine : most of the univalve shells, such as whelks, limpets, cow- 
ries, and many of the beautiful convoluted shells of tropical countries, 
belong to this class. 
2038. The second class, or mother-of-pearl shells, are tougher, 
glossy, and iridescent; they are mostly bivalves, and all the oyster 
and muscle species belong to it. When heated, they exhale smoke 
and the smell of burned horn ; immersed in muriatic acid, they only 
partially dissolve, and leave a series of cartiliginous layers, and ail 
outer epidermis. Each membrane appears to have a corresponding 
stratum of carbonate of lime, the solution indicating no trace of any 
phosphate. The animal part is in some cases, as in mother-of-pearl, 
tough and indurated, and when dried becomes exactly like horn ; in 
•ther instances, as in the bone of the cuttle fish, it appears in the form 
©f delicate and tender membrane. 
In both classes of shells, therefore, the hardening principle is car- 
bonate of lime ; in porcellaneous shells there is very little animal 
matter, which is gelatine ; and in mother-of-pearl shells, it is albumen, 
and in larger quantities 
2039. Pearls are exactly similar in composition to what is termed 
mother-of-pearl, in which Mr. Hatchett found 
Carbonate of lime . . . 
. ... 66 
Albumen 
100 
2040. In the scales of fish, and in the crusts of lobsters, crabs, prawns, 
and cray-fish, Mr. Hatchett found the animal portion to consist of car- 
tilage ; the hardening part was a mixture of carbonate and phosphate 
of lime. From lobster-shell Merat-Gulliot obtained 
Carbonate of lime .... 
Phosphate of lime .... 
. . . 14 
Cartilage 
100 
Vauquelin obtained from 100 parts of /ten’s egg-shell 
Carbonate of lime .... 
Phosphate of lime .... 
Animal matter 
100 
2041. Zoophytes, according to Mr. Hatchett’s researches, may be 
divided into four classes; the first resemble porcellaneous shells, and 
consist entirely of carbonate of lime, with a very minute quantity of 566 
TEETH. 
gelatinous matter; of this the common white coral {madrepora virginea) 
is an example. The second consists of carbonate of lime, and a car- 
tilaginous substance, and are therefore analogous to mother-of-pearl 
shell; to this class belong the madrepora ramea, and madrepora fasci- 
cularis. The third class is composed of a cartilaginous matter, with 
carbonate and phosphate of lime ; to this belongs the red coral (gor- 
gonia nobilis). The fourth class contains sponges, composed almost 
entirely of albuminous matter.—Phil. Trans., 1800. 
2042. Bone, and Ivory, like the preceding substances, is essentially 
composed of soft and hard parts. When ground bone is digested in 
warm water, a portion of fat is first separated, and by long-continued 
ebullition, a solution which gelatinizes on cooling is obtained. If fresh 
bone be immersed in diluted muriatic acid, the fat, gelatine, and hard- 
ening matter are dissolved, and a kind of skeleton of the bone remains 
in the form of a cartilaginous substance, which when dried exactly re- 
sembles horn. It appears, therefore, that the soft parts of bone are, 
fat, gelatine, and albumen. 
The earthy salts, which constitute the hardening principle of bone, 
are phosphate and carbonate of lime, with a minute quantity of sul- 
phate of lime, and traces of phosphate of magnesia. Fourcroy and 
Vauquelin obtained from ox-bones, 
Animal matter - 
- - - 51 
Phosphate of lime ------ 
- - - 37.7 
Carbonate of lime ------ 
- - - 10 
Phosphate of magnesia - - - 
- - - 1.3 
100 
2043. The enamel of teeth is perfectly destitute of cartilage, and con- 
lists chiefly of phosphate of lime and a portion of gelatine. Mr. Pe- 
pys found its component parts 
Phosphate of lime - - - - - 
.... 78 
Carbonate of lime - - - - 
.... 6 
Gelatine - - - - 
.... 16 
100 
The same chemist has given the following as the composition of 
the teeth (Fox, On the Teeth) : 
Roots of 
the teeth 
Teeth of 
Adults 
First teeth 
of Children 
Phosphate of lime - 
- 58 - - 
- - 64 - 
- - - 62 
Carbonate of lime . 
- 4 - - 
- - 6 - 
- - - 6 
Cartilage - - - - - 
- 28 - - 
- - 20 - 
- - - 2 
Loss -------- 
- - 10 - 
- - - 12 
too 
too 
100 
2044, When bones are submitted to destructive distillation, the ge- 
latine and albumen which they contain is abundantly productive of am- 
monia ; water, and carbonic acid are al6* formed and a portion of DIGESTION. 
567 
highly foetid empyreumatic oil. There remains in the vessel a quantity 
of charcoal mixed with the earthy substances, which is, in that state, 
called ivory black. It is employed as the basis of some black paints 
and varnishes. 
Section XII. Of Animal Functions. 
2045. Chemistry has hitherto done little towards elucidating the 
functions of animals, and it is scarcely possible to describe the little 
that has been done, without such frequent reference to anatomical and 
physiological inquiries as would be irrelevant to the present work ; I 
shall, therefore, only enumerate the principal chemical phenomena 
that have been experimentally illustrated, in relation to this subject. 
2046. Digestion is a process by which the food of animals is convert- 
ed into chyle, and which, in conjunction with respiration, tends to the 
production of blood. The mechanism by which it is carried on differs 
considerably in the different classes of animals ; the present remarks 
will relate chiefly to man, and to the carnivorous tribe. 
The food, duly masticated in the mouth, and blended with a consi- 
derable portion of saliva, is propelled into the stomach, where it soon 
undergoes a remarkable change, and, in the course of a few hours, is 
converted into an apparently homogeneous pulpy mass, which has 
been termed chyme, and which has little or no resemblance to the ori- 
ginal food. This very curious change is only referable to the opera- 
tion of a secretion peculiar to certain glands of the stomach ; it has 
been termed gastric juice, and all that is known respecting it is, that 
it has very energetic solvent powers, in regard to the greater number 
of animal and vegetable bodies ; the remarkable property of living sub- 
stances to resist its action is curiously illustrated by the circumstance 
that the stomach itself, after death, is occasionally eaten into holes by 
its action ; it instantly coagulates all albuminous substances, and after- 
wards softens and dissolves the coagulum. There are some substan- 
ces that remarkably resist its action, such as the husk of grain, and of 
many seeds, which, if not previously broken by mastication, pass 
through the stomach and bowels nearly unaltered. It is hardly worth 
while to detail the experiments that have been undertaken on the gas- 
tric juice, since they are much at variance, and it is impossible to say 
whether the secretion has ever been examined in a state even ap- 
proaching to purity. It has been described as a glairy fluid, of a 
saline taste ; sometimes it is said to be acid, and sometimes bitter ; but 
no light whatever has heen thrown by any of these researches upon 
the cause of its singular solvent energies. 
It has sometimes been matter of surprise, that although animals drink 
copiously with their food, the consistency of the chyme is not affected 
by it, and by the time that it reaches the right, or pyloric extremity of 
the stomach, the liquid has disappeared. Sir Everard Home’s curious 
physiological researches have shown that liquids are copiously and ra- 
pidly removed by absorbents belonging principally to the left, or car- 
diac portion of the stomach, and that during digestion there is au im- 
Chyme. 
Absorption 
from tbe 
stomach USE OP THE BILE. 
perfect division of the stomach into two cavities, by the contraction of 
the bands of muscular fibres about its centre. He has also shown that 
these liquids, very soon reach the kidneys, and pass off by urine ; and 
was led to believe that the spleen was the channel of communication ; 
an opinion, however, which his subsequent researches tended to dis- 
prove.—Lectures on Comparative Anatomy, p. 221. 
The chyme passes from the stomach into the small intestines, where 
it soon changes considerably in appearance ; it becomes blended with 
bile, and is separated into two portions, one of which is white as milk, and 
is termed chyle; the other passes on to the large intestines, and is ulti- 
mately voided as excrementitious. The chyle is absorbed by the lac- 
teals, which terminate in the common trunk, called the thoracic duct; 
it is there mixed with variable proportions of lymph, and poured into 
the venous system. 
The excrements of animals have been examined by Berzelius, (Geh- 
een’s Journal, vi.) ; by Vauquelin, (Annales de Chimie, xxix.) ; and by 
Thaer and Einhoff. An abstract of these experiments has been pub- 
lished by Dr. Thomson, in the 4th volume of his System of Chemistry. 
2047. Chyle has been examined by several chemists, and their re- 
sults are not widely different. During some physiological researches 
in which I assisted Mr. Brodie, 1 had an opportunity of collecting it in 
considerable quantities in several carnivorous and graminivorous ani- 
mals, and presented an account of my experiments upon it to the Royal 
Society.—Phil. Trans., 1812, p. 91. 
Chyle is an opaque white fluid, having a sweetish saline taste; its 
specific gravity is inferior to that of the blood. It exhibits slight traces 
of alcaline matter when tested by infusion of violets ; soon after re- 
moval from the thoracic duct, it gelatinizes spontaneously, and after- 
wards gradually separates into a firm yellowish white coagulum, and 
a transparent colourless serum ; so that, like the blood, it enjoys the 
property of spontaneous coagulation. 
The coagulum of chyle possesses properties closely resembling those 
of the caseous portion of milk, and may hence be considered as a va- 
riety of albumen ; the serum of the chyle, when heated, deposits a few 
flakes of albumen, and by evaporation to dryness affords a small pro- 
portion of a substance analogous to sugar of milk. Small portions of phos- 
phate of lime, carbonate of soda, and common salt, may also be detect- 
ed in the chyle. In these experiments I found no distinctive difference 
in the chyle of graminivorous and carnivorous animals ; I examined it 
from the horse, the ass, the dog, and the cat ; Dr. Marcet thinks that 
the former is less abundant in albumen than the latter*.—Thomson’s 
Annals, Vol. vii. 
2048. There can be little doubt that the bile performs an important 
part in the change which the chyme suffers in the small intestines ; it 
has been conjectured that its aqueous, and perhaps its alcaline, parts, 
are employed as components of chyle, while the albumino-resinous 
matter combines with the excrementitious portion, and tends to stimu- 
late the intestinal canal towards promoting its propulsion. Whether 
Ohyle. 
Characters. 
Kile. 
* It is a curious question, whence the nitrogen, which constitutes an abundant ultimate 
principle of the chyle of herbivorous animals, is derived ; we find it in very small proportion 
only in their ordinary food, and yet I could discern no difference in the composition of the al'- 
buminohs portion of their chyle, and that of animals fed exclusively on meat. 569 
the bile is absolutely necessary to the formation of chyle, is a question 
that has not been satisfactorily answered ; but its importance is demon- 
strated by the emaciation that attends its deficiency, and by the disor- 
dered state of bowels that accompanies its imperfect secretion. Sir 
Everard Home, in his Lecture on the Functions of the Lower Intestines, 
(Lectures, p. 468.) has offered some curious facts connected with this 
subject, to which I refer the physiological reader. He is of opinion 
that, in the large intestines, a portion of the food unfit for chylification is, 
*>y a process not widely different from that above described, (1951) 
converted into fat, which is afterwards absorbed and conveyed to dif- 
ferent parts of the body. 
2049. In chyle we cannot fail to observe a close approximation to 
blood : it is deficient only in colouring matter, and the albumen which 
it contains differs a little from that existing in the blood itself; it ap- 
pears, therefore, that the albumen is perfected, and the colouring mat- 
ter formed, in the process of circulation ; the saccharine principle of 
the chyle is also no longer perceptible. 
2050. The difference between arterial and venous blood, has been 
adverted to in a previous section ; the former is of a florid red co- 
lour, and circulates in the arterial system ; it is contained in the left 
ventricle of the heart, and thence carried by the aorta, and its ramifi- 
cations, to every part of the body, tending to re-production and secre- 
tion : it afterwards enters the veins which arise from the extremities 
of the arteries, and form accompanying branches and trunks ultimate- 
ly uniting in the vence cavce, which pour their contents into the right 
auricle of the heart; the venous blood is thence propelled into the 
right ventricle, from which the pulmonary artery arises, transmitting 
it through the lungs, whence it is returned by the pulmonary vein into 
the left auricle, which transmits it to the left ventricle, from which is- 
sues the aorta as aforesaid. So that the right cavities of the heart re- 
ceive venous blood, and transmit it through the lungs, whence it re- 
turns to the left side of the heart, in the arterial state. In the lungs 
the blood is infinitely subdivided, and spread over a very large surface 
in vessels so delicate as to admit of the operation of the atmospheric 
air contained in their cells ; it enters the pulmonary structure in the 
venous state by the pulmonary artery, and returns in the arterial or ae- 
rated state, by the pulmonary vein. It now remains to examine the 
changes which the blood undergoes during pulmonary circulation. 
2051. Respiration is the process of receiving a quantity of air into 
the lungs, whence, after having been retained a short time, it is again 
expelled in the action of exspiration ; and, if now examined, a portion 
of its oxygen is found converted into carbonic acid, and it is more or 
less loaded with aqueous vapour. 
Obvious circumstances render it very difficult to ascertain the quan-i 
tity of air taken into the lungs at each natural inspiration, as well asf 
the number of respirations made in a given time ; the former is per- 
haps about 15 or 16 cubic inches, and the latter about 20 in a minute. 
It has been by some supposed that the air suffers an absolute diminu- ( 
tion of bulk, but the experiments that have been adduced to prove3 
this, can, I think, scarcely be regarded as satisfactory; it seems, on the 
contrary, most probable that the volume of air expired is exactly equal 
to that inspired, and consequently the only chemical change that is evi- 
dent is the saturation of a portion of its oxygen with carbon, f he 
RESPIRATION. 
Numberof res- 
pirations. 
ChangeSof the 
air respired. respiration. 
quantity of carbonic acid emitted at each exspiration, varies at differ* 
ent periods of the day, and probably also in different individuals ; it 
appears at its maximum during digestion, and at its minimum in the 
morning, when the stomach is empty, and when no chyle is flowing 
into the blood. Dr. Prout has shown that fermented liquors and ve- 
getable diet diminish the proportion of carbonic acid, and that the 
same thing happens when the system is affected by mercury. (Thom- 
son’s Systein, iv. 621.) 
The air expired maybe regarded, I think, as containing, on an ave- 
•rage, 3.5 per cent, of carbonic acid, though Messrs. Allen and Pepys, 
in their valuable Essay on Respiration, {Phil. Trans., 1808.) have es- 
timated it at about twice that quantity ; it amounted, in their experi- 
ments, to 27.5 cubic inches per minute, a quantity probably above the 
truth, when we reflect upon the comparative proportion of carbon ex- 
isting in our food, and the other means of escape which it has from the 
body. 
The aqueous vapour contained in the expired air is secreted b}r the 
exhalents distributed over the surface of the air-vessels of the lungs ; 
attempts have been made to estimate its quantity, but without success ; 
it is probably liable to variation, and can scarcely be considered as a 
product of respiration. 
It has been above stated that the whole of the venous blood is pro- 
pelled through the vessels of the lungs, where it is subjected to the- 
action of the air ; the chyle is of course carried along with it, and when 
it returns by the pulmonary vein to the left side of the heart, it has 
undergone a considerable change in appearance, having lost its dingy 
colour, and acquired a fine florid red ; the chyle also has become per- 
fect blood. The change of colour is evidently owing to the action of 
the air, which takes place through the thin coats of the circulating 
vessels, and the end thus attained is the removal of the carbon from 
the venous blood, by which the colouring matter was obscured : the 
carbon to be thus readily soluble in oxygen must be in some peculiar 
state ; a portion of it is also removed by the absorbents, and transferred 
to the glands situ-ate at the root of the lungs between the subdivisions 
of the bronchias, which often contain a large portion of black matter. 
This has sometimes been referred to soot inhaled with the air, but 
many circumstances render it more probable that it is a carbonaceous 
deposit from the blood. The only chemical difference, then, which 
can be detected between arterial and venous blood, is the existence of a 
certain excess of carbon in the latter, which it gives off to oxygen, 
forming carbonic acid ; the blood is thus fitted for the renovation of 
parts, for the formation of secretions, and for the sustenance of life by 
its action on the cerebral system; for although the heart does not di- 
rectly refuse to circulate venous blood, paralysis and torpor ensue 
when blood, not aerated, passes into the vessels of the brain. 
2052. It has already been shown that the blood suffers very impor- 
tant changes in the kidneys and liver ; the function of perspiration also 
must be considered as connected with an alteration of the circulating 
fluid, for moisture, carbonic acid, and minute quantities of phosphoric 
acid, and saline matter, among which is common salt, are evacuated by 
the cutaneous vessels. This quantity of humidity is sometimes very 
considerable, especially during violent exercise in warm weather, and 
>t contributes materially to diminish the temperature of the body ; a 
Quantity of 
carbonic acid 
Perspiration. ANIMAL HEAT. 
571 
portion of water, however, is at all times passing off by the skin, as 
may be seen by putting the hand into a dry and cold glass, which soon 
becomes dimmed by the condensation of vapour. 
2053. Different animals require very different quantities of oxygen 
for the purposes of respiration. Man, and warm-blooded animals, 
consume the largest quantity ; the amphibious tribes not only require 
less, but can breathe in an atmosphere which will not support the life 
of the former ; and many insects take such small quantity, as some- 
times to have been supposed capable of living without air, which is not 
the case. In the production of carbonic acid all animals agree, and 
consequently the nature of the deterioration suffered by the air is 
similar throughout the animal creation. 
Fishes breathe the air which is dissolved in water; they therefore 
soon deprive it of its oxygen, the place of which is supplied by car- 
bonic acid; this is in many instances decomposed by aquatic vege-i 
tables, which restore oxygen, and absorb the carbon (1535) ; hence 
the advantage of cultivating growing vegetables in artificial fish-ponds, 
it has been ascertained by Biot, and verified by others, that the air- 
bladders of fish that live in very deep water are filled with a mixture 
of oxygen and nitrogen, in which the former greatly preponderates ; 
but in fish that are taken near the surface, the nitrogen is most abun- 
dant. In the trygla lynx, -always caught in very deep water, the air- 
bladder contained 87 per cent, of oxygen : in the carp and roach, ac- 
cording to Fourcroy and Priestley, the air-bladder contains little else 
than nitrogen.—Biot, Mimoires d’ Arcueil, i. & ii. 
2054. The production of animal heat is perhaps the most recondite 
of all the functions; the power appears to belong to all animals, 
though to some in a very inferior degree. The higher orders of ani- 
mals always maintain a temperature of about 100° ; it varies a little in 
different parts of the body, the extremities and surface being a degree 
or two colder than the interior vital organs. This temperature is pro- 
bably very little affected by external circumstances, a hot or cold at- 
mosphere producing no corresponding change in the heat of the cir- 
culating blood. 
When the chemical changes that take place during respiration had 
been inquired into, and when it was found that the capacity of carbon- 
ic acid for heat was less than that of oxygen, it was supposed that the 
conversion of oxygen into carbonic acid was the cause of the rise o] 
temperature : and as the heat of the lungs does not exceed that ol 
other parts, it was asserted that the air was absorbed by the blood, and 
that the production of carbonic acid, and consequent evolution of heal 
took place gradually during the circulation. To these opinions many 
strong objections have from time to time been urged by different phy- 
siologists, but their complete subversion followed the researches oi 
Mr. Brodie, (Phil. Trans., 1812.) who found that the heart was capa- 
ble of retaining its functions for some hours, and of carrying on circu- 
lation in a decapitated animal, and consequently independent of the in- 
fluence of the brain, when respiration was artificially carried on. 
Under these circumstances it was observed, that although the change 
of blood from the venous to the arterial state was perfect, no heat was 
generated, and that the animal cooled regularly and gradually down to 
the atmospheric standard. In more than one instance I examined, at 
his request, the expired air, and foupd that it contained as much car- 
Unequal quan- 
tities of oxy- 
gen necessary 
to different 
animals. 
! Animal heat. 572 
GEOLOGY. 
bonic acid as was produced by the healthy animal; so that here, circu- 
lation went on, there was the change of oxygen into carbonic acid, and 
the alteration of colour in the blood, and yet no heat whatever appear- 
ed to be generated. 
In these cases a period was also put to the secretory functions ; and 
it has been observed by several other physiologists, that if the nerves 
that supply any of the glands are injured or divided, there is a corres- 
ponding change or suspension of their secretion. Electricity has some- 
times been supposed to have some connexion with the nervous influ- 
ence, and the fact of some of the secretions being alcaline, while 
others are acid (correspondingto negative and positive influence), has 
been adduced in favour of the supposition*, but experiment has gone 
little way to sanction such a notion, and although it has been proved 
that the nervous influence contributes to the generation of heat in an- 
imals, that it presides over the phaenomena of secretion, as well as of 
voluntary motion, the actual cause of this influence, or energy, re- 
mains among those mysteries of nature which, doubtless, for the 
wisest purposes, are hidden to the human understanding. 
CHAPTER X 
GEOLOGY. 
2055. Having detailed the properties of the elementary bodies, and 
of their natural and artificial combinations, and having described the 
products of the vegetable and animal creation, it remains in this, the 
* In the Philosophical Transactions for 1809, p. 385, Sir Everard Horae has given an ac- 
count of these views, in a paper entitled Hints on the Subject of Animal Secretions. burnet’s theory. 
573 
concluding chapter, to notice the general arrangements of the mineral 
world, to describe the mutual relations of the substances constituting 
the surface of our globe, and to examine their characters and compo- 
sition ; these investigations form the object of geological science. 
Section I. General Remarks on the Objects of Geological Science.— 
Sketch of the Theories of Burnet, Woodward, Leibnitz, Whiston, White- 
hurst, and Buffon.—Wernerian and Huttonian Theories. 
2056. Geology embraces so many topics of discussion, its range is 
so extensive, and the meanings given to the term are so various and 
opposite, as to throw no inconsiderable difficulties in his way who 
would enumerate and expound them. Persons have been called geo- 
logists, who, gifted with prolific imaginations, have indulged in fanciful 
speculation concerning a former order of things, and have reared hy- 
potheses respecting the origin of our planet, upon foundations so flim- 
sy and unsubstantial, as (o deserve no other appellation than flighty 
excursions of a poetic mind. Others, by careful, diligent, and extend- 
ed observations of the present state of the earth’s surface, have en- 
deavoured, in the path of induction, to trace the nature of the agents 
which have once been active, to ascertain how far they are now operat- 
ing, and to anticipate the results of their continuance. If they frame 
theories, they do so upon the results of actual research ; if they in- 
dulge in speculation, they assign to it its proper place. These are real- 
ly geologists, and their aim is, not to imagine or suppose, but to disco- 
ver the nature of all changes of the earth’s surface and interior, and 
thence to arrive at the laws that regulate them. 
Geology, as a branch of inductive science, is of very modern date ; 
for though the attention of men has long been turned to a theory of the 
earth, the formation of such a theory is incompatible with any but an 
advanced state of physical knowledge. There appear, indeed, few 
studies of more difficulty ; none in which the subject is more complex ; 
appearances so diversified and scattered ; and where the causes that 
have operated are so remote from the sphere of ordinary observation. 
£057. The first writer upon this subject, whose name merits notice, 
is Thomas Burnet*, who may justly be said to have adorned the 
latter half of the seventeenth century. And though it be true that his 
pen has rather recorded the sallies of a vivid imagination, than the in- 
ferences of sober argument, he will still be read with some profit, 
though certainly with more pleasure, even in these times. The ob- 
jection to Burnet and his contemporaries, and immediate successors, is, 
that they fancifully go back to the chaotic state of the earth, and after 
enlarging, embellishing, and obscuring the Mosaic history, they pretend 
to have illustrated and proved it. Accordingly, Burnet, in his Sacred 
* The Sacred Theory of the Earth, containing an account of the Original of the Earth, 
and of all the General Changes which it hath already undergone, or is to undergo, till the 
Consummation of all Things. (8vo., London, 1726.) Published originally in Latin in 1681 
and 1689. 574 
burnet’s theory. 
Theory of the Earth, begins with the separation of elements from a fluid 
mass. The heaviest particles sank, and formed a nucleus, and water 
and air took their respective stations : upon the water, however, the 
air afterwards deposited a rich unctuous crust, which begat vegetation, 
and a beautiful verdure clothed the whole. There were no moun- 
tains, no seas, no protuberances, or inequalities ; and the equator be- 
ing coincident with the plane of the ecliptic, all the charms of spring 
were perpetual. This state of things, however, did not thus continue 
for many centuries ; for the sun caused large cracks and fissures in the 
exterior, which, by gradual increase, extended to the great aqueous 
abyss ; the waters rose higher and higher, the surface was utterly bro- 
ken up and destroyed, and an universal deluge took place: at length 
dry land began again to appear, owing to a gradual subsidence of the 
waters, which retired into caverns and crevices originally existing in 
the nucleus, or formed by the disruption of the crust; upon the in- 
creasing dry land, vegetation began again to exist, and our present is- 
lands and continents were formed, while the sea still occupies in part 
its original bed. 
I do not recite the minutiae of Burnet’s romance, nor shall I meddle 
with the adjustments of these and the like speculations to the records 
of Holy Writ. 'If, in the laborious path of experimental investigation, 
we are occasionally rewarded with the discovery of some new adapta- 
tions of causes and effects, which had before escaped notice, but which 
demonstrate how all things on earth are made to work together for 
good, the discovery strengthens our faith, and calls forth the best feel- 
ings of which the human heart is susceptible; but we must not pre- 
sume to submit the aptitude of nature’s arrangements to the feeble 
powers of human decision, to doubt her perfection, because our im- 
becile capacities cannot attain its comprehension, or to found our 
proofs of the existence, or even of the attributes, of the Deity, upon 
the limited, imperfect, or ideal conception of the excellence of na- 
ture’s works, ef which the human understanding is capable. 
Although Burnet’s Theory, as he calls it, was a mere hypothetical 
product of the imagination, unsupported by a single fact, or by the 
slightest observed phenomenon, it excited much admiration and some 
discussion, and was criticised with much acrimony and some ability* ; 
more especially by Keill, of Oxfordf. His style is in general terse 
and elegant, though it occasionally degenerates into the predominant 
pomposity of the period at which he wrote. He was the translator 
of his own work from Latin into English. Two brief samples from the 
latter will be sufficient for elucidation. After observing that the ob- 
scurity and remoteness of his subject has by some been used as aa 
argument against undertaking it, “ This,” says he, “ does but add to 
the pleasure of the contest where there are hopes of victory, and suc- 
cess more than recompenses all the pains. No joy is more grateful to 
* By Dr. Herbert Crofte, in 1685: by Dr. Beaumont, in 1693, and by Erasmus Warren, 
f An Examination of Dr. Burnet's Theory, &c., by J. Keill. A. M., of Baliol Coll., 
Oxon. Second Edition, 1734, 8vo. “ He (Burnet) begins his discourse with a saying of an 
old heathen, that philosophy is the greatest gift that ever God bestowed on man; but it is plain 
to any who will be at the pains to read his book, that God has thought fit to bestow but very 
little of that great gift upon him, and, that the world may not say this is ill-nature, 1 will give' 
them a taste of his phylosophy,” fyc. 
This is the general style of the Examination\ BURNEt's THEORY. 
man than the discovery of truth, especially where it is hard to come 
by. Every man has a delight suited to his genius, and as there is plea- 
sure in the right exercise of any faculty, so especially in that of right 
reasoning, which is still the greater by how much the consequences 
are more clear, and the chains of them more long. There is no chase 
so pleasant, methinks, as to drive a thought from one end of the world 
to the other, and never to lose sight of it till it falls into eternity, where 
all things are lost, as to our knowledge.” 
The following passage from Burnet’s work has been highly eulogiz- 
ed by Steele*, and certainly it merits praise ; it is a funeral oration 
over the globe : “ Let us now,” says he, “ reflect on the transient 
glory of the earth ; how, by the force of one element breaking loose 
on the rest, all the beauties of nature, each work of art, and every la- 
bour of man are reduced to nothing ; all that once seemed admirable, 
is now obliterated ; all that was great and magnificent, has vanished ; 
and another form and face of things, plain, simple and uniform over- 
spreads the earth. Where are now the empires of the world ? where 
the imperial cities, the pillars, trophies, and monuments of glory ? 
what remains, what impressions or distinctions do you now behold ? 
what is become of Rome, the great city ; of eternal Rome, the em- 
press of the world, whose foundations were so deep, whose palaces 
were so sumptuous ?—her hour is come ; she is wiped from the face 
of the earth, and buried in everlasting oblivion. But not the cities 
only, and the works of men’s hands, but the hills and mountains, and 
rocks of the earth, are melted as wax before the sun, and their place 
is no where found ; all have vanished and dropped away, like the snow 
that once rested upon their summits!.” 
It is impossible to read this quotation, without being reminded of one 
®f the most beautiful passages in the Art of Preserving Health, where 
Armstrong has happily introduced very similar ideas : 
What does not fade ? the tower that long had stood 
The crash of thunder and the warring winds, 
Shook by the slow, but sure destroyer, Time, 
Now hangs in doubtful ruins o’er its base; 
And flinty pyramids, and walls of brass, 
Descend: the Babylonian spires are sunk; 
Achaia, Rome, and Egypt moulder down; 
Time shakes the stable tyranny of thrones, 
And tottering empires rush by their own weighty 
This huge rotundity we tread grows old, 
And all those worlds that roll around the sun, 
The sun himself shall die, and ancient night 
Again involve the desolate abyss}:. 
I might select many more beauties from the Sacred Theory of the 
Earth. The passages I have quoted, however, show the general 
* Spectator, No. 146. 
Attached to the English edition of Burnet’s work, above referred to, is an “ Ode to the Au- 
thor, by Mr. Addison,” in the ordinary fulsome style of that period. The following stanza is 
a specimen: 
Jamque alta Coeli moenia corruunt, 
Et vestra tandem pagina, (proh nefas!) 
Burnette, vestra augebit ignes, 
Heu ! socio peritura Mundo. 
1 Burnet's Theory, Vol. ii., p. 25. 
| drl of Preserving Health, B. ir. 576 
Whitehurst’s theory. 
strain of the author, and it would be irrelevant amusement to pursue 
them. 
2058. Avery different reasoner from Burnet was Woodward ; he 
was nothing of a poet, and not much of a philosopher ; he pretends to 
be a matter-of-fact man ; but having collected a few observations res- 
pecting the contents of strata, hastily proceeded to the erection of a 
theory ; “ to build a ship,” as Lord Bacon says, “ with materials insuf- 
ficient for the rowing-pins of a boat.” Woodward observed the exist- 
ence of fossil shells, and remarked that the lower strata of the earth’s 
surface were generally harder than the upper, which were of more 
light and pulverulent materials : whence he concluded, that at the pe- 
riod of the deluge, the earth had acquired a new crust deposited upon it 
by the waters, in the succession of the specific gravity of the materi- 
als ; the heaviest, coarsest, and hardest bodies forming what to us 
seem a nucleus, covered by finer and lighter deposits*. 
2059. About this time Leibnitz published his Protogcea] ; he sup- 
poses the earth to have been in a state of combustion for many ages, 
and at length to have gone out for want of fuel. A glassy crust was 
thus formed, which gave rise to sand and gravel; other kinds’ of earth 
resulted from sand and salt; and as the globe cooled, the water which 
had before been kept in the state of steam, assumed fluidity, and, fall- 
ing to the earth produced the ocean. The particulars of these notions 
are, of course, not worth reciting. 
2060. WhistonJ having blended the follies of Burnet, Woodward, 
and Leibnitz, endeavours to conceal his imbecility under the lion’s 
skin of mathematical calculation ; and taking many things for granted, 
of which there is not the most distant probability, leaves us bewilder- 
ed and perplexed; he is neither plausible nor amusing, and is best 
known as having called forth the libellous witticism of Swift. 
2061. But there was a contemporary of Whiston, whose works de- 
serve more attention ; John Whitehurst§, a native of Congleton, in 
Cheshire ; he passed much of his time in Derbyshire, and investigated, 
with considerable ability, the stratification of that rich and interesting 
county ; “ hoping,” as he expresses it, “ to obtain such knowledge of 
subterraneous geography, as might be subservient to the purposes of 
life, by exposing new treasures which are concealed in the lower 
regions||.” In his inquiry into the original state and formation of the 
* Woodward applied the geological observations he had made in England to other coun- 
tries. “ I was abundantly assured that the circumstances of these things in remoter countries 
were much the same with those of ours here; that the stone and other terrestrial matter in 
France, Flanders, Holland, Spain, Italy, Germany, Denmark, Norway, and Sweden, was dis- 
tinguished into layers, as it is in England, 4-c. 4'C. To be short, I got intelligence that these 
things were the same in Africa, Arabia, Persia, and other Asiatic provinces; in Ame- 
rica,” 4 c. See An Essay towards a JVatural History of the Earth and Terrestrial Bo- 
dies, by John Woodward, M. D., fyc, London, 1702. 
f Leibnitzii Opera Omnia. Geneva;, 1768. Vol. ii. p. 199. 
t JVew Theory of the Earth, &c. By William Whiston, M. A. 4th Edition, London, 1725. 
§ The Works of John Whitehurst, F.R.S., London, 1729. “It is my intention (says 
Whitehurst, in his Preface to the Inquiry into the Original State and Formation of the 
Earth, to trace appearances in nature from causes truly existent; and to inquire after those 
laws by which the Creator chose to form the world, not those by which he might have formed 
it, had he so pleased.” 
S Whitehurst particularly notices the similarity of succession in the strata of England: 
in his description of Derbyshire, he mentions the resemblance of the toadstone to lava, 
and infers, from its appearance, situation, and effects, that it must have issued from below in 
an ignited state; that it must have been projected with great violence amidst the superincum- 
bent strata, and that their displacements and irregularities are the consequence. earth he has assiduously collected facts, among which his account of 
the strata of Derbyshire retains much value at the present day, though 
repeated investigations have since been made with all the advantages 
©f modern improvements. And as to his theoretical views, I think it 
is scarcely going too far to say, that they are the best extant: for, un- 
like latter geologists, he first collected facts and then constructed his 
theories ; and those who are unbiassed by speculative doctrine, and 
really think for themselves, will consequently accede to by far the 
greater number of his leading propositions. 
2062. But no one has proceeded to the forming of a theory of the 
earth with the pomp and circumstance of Buffon*. It merits attention, 
not on account of its accordance with present appearances, or as af- 
fording plausible solutions of observed phenomena, but from the elo- 
quence with which it is adorned, the extent of information it displavs, 
and the popularity it derived from these sources. 
He supposes the planets in general to have been struck off from the 
sun by a comet; that they consisted of fluid matter-, and thence as- 
sumed a spherical form ; and that by the union of centrifugal and cen- 
tripetal forces they are restrained in their present orbits. The earth 
gradually cooled, and the circumambient vapours condensed upon its 
surface, while sulphureous, saline, and other matters, penetrated its 
cracks and fissures, and formed veins of metallic and mineral products. 
The scorified, or pumice-like surface of the earth, acted upon by wa- 
ter, produced clay, mud, and loose soils ; and the atmosphere was con- 
stituted of subtile effluvia, floating above all the more ponderous ma- 
terials. Then the sun, and winds, and tides, and the earth’s motion, 
and other causes, became effective in producing new changes. The 
waters were much elevated in the equatorial regions, and mud, gravel, 
and fragments were transported thither from the poles; hence, says 
Buffon, the highest mountains lie between the tropics, the lowest to- 
wards the poles ; and hence the infinity of islands which stud the tro- 
pical seas. The globe’s surface, once even and regular, became now 
rough and irregular ; excavations were formed in one part, and land 
was elevated in another ; and during a period of ages, the fragments 
of the original materials, the shells of various fish, and different other 
exuviae, were ground up by the ocean, and produced calcareous strata, 
and other low-land depositions. These relics of marine animals we 
find at such heights above the present level of the sea, as to render it 
more than probable that the ocean once entirely overwhelmed the 
earth. 
Of the phaenomena I have hinted at, Buffon takes particular afid ex- 
tended notice, and draws from them a series of curious and minute 
conclusions ; not, however, satisfactory or logical, inasmuch as many 
of the data they are founded upon are imaginary, not real. Every one 
who now comtemplates the earth’s surface, must trace upon it marks 
of the most dire and unsparing revolutions, which, from the present 
order of things, it appears impossible should re-occur, except by the 
united and continuous agency of the most active powers of destruction. 
This, says Buffon, arose from the soft state of the former crust of the 
earth; and those causes, now imbecile and slow in their operation, 
buffon’s theory. 
* Hisioire et Theorie de la Terre et des Epoques de la JYatnre, 4 Vol. 8vo, Paris, 180P, WERNER AN* HtfTTON. 
were then more effectually exerted, and results were obtained in a 
few years, for which centuries would now be insufficient. 
This amusing theorist next proceeds to contemplate the production 
of rivers, which he regards as having cut their own way to the ocean, 
as gradually wearing down the mountainous lands, filling up valleys, and 
choking their exits into the ocean by the transportation of finely-divid- 
ed materials. Thus every thing is slowly returning to its former 
state ; the mountains will be levelled, the valleys heightened, excava- 
tions filled up, and the ocean will again cover the earth. 
1 shall not enter into the various confutations of these speculative 
notions, nor dwell upon many modern theories to which they have 
given rise. Pallas, Kirwan, De Luc, and others, have animadverted 
upon, but can scarcely be said to have improved, Buffon’s hypothesis ; 
and as we set out with granting it to be the mere fabric of imagination, 
it would be folly to submit it to the solemnity of philosophic criticism. 
2063. Many other theories of the earth I pass over in silence, as 
containing nothing not to be met with in some of the already mentioned 
cosmogonists. The authors have sometimes clothed their fictions in 
new dresses, or presented them under new forms ; but, if we remove 
the mask, Burnet or Buffon are instantly recognised. Thus, in pre- 
tending to advance learning, they have rather obstructed it, and have 
accumulated hypotheses without enriching science. They deserve 
that censure thrown upon certain writers by Dr. Johnson, who calls 
them the “ persecutors of students, and the thieves of time.” Such 
at least I have found them. 
There are other geological writers who have accumulated many in- 
teresting facts, and whose insulated observations are truly curious and 
valuable ; but their general hypotheses are of so chimerical a cast, as 
rather to resemble Eastern allegories than European philosophy; they 
defy all criticism, and therefore lie out of our present track, which 
now leads us to review the prevailing theories of the present day. These 
are the inventions of Professor Werner, ofFreyburgh*, and Dr. Hutton, 
of Edinburgh!, each of whom has been ably supported and elucidated by 
the proofs, illustrations, and comparative views of acute and eloquent 
controversialists];, and two sects have been formed, under the appella- 
tion of Wernerians and Huttonians. The disputes and differences of 
these contending geologists would now be prematurely noticed. They 
each profess to proceed, as rigidly as the subject allows, in the path of 
induction ; to reject mere hypothesis, and raise their theories upon ac- 
cumulated facts ; and yet they arrive at conclusions diametrically oppo- 
site ; upon which a clever writer remarks, “ that among all the won- 
ders geology presents to our view, the confidence of the theorists is by 
far the most unaccountable.” 
2064. The first principle of the Wernerian theory assumes, that 
our globe was once covered with a sort of chaotic compost, holding 
either in solution or suspension the various rocks and strata which now 
* A Comparative View of the Huttonian and Neptunian Systems of Geology. Edin- 
burgh, 1802. 
f Theory of the Earth. By James Hutton, M.D., F.R.S., Edinburgh, 1795. 2 Vols. 8vo. 
t Illustrations of the Huttonian Theory of the Earth. By John Playfair, F.R.S., 4‘C-, 
Edinburgh, 1802. mutton’s theory. 
579 
present themselves as its exterior crust. From some unexplained 
cause, this fluid began first to deposit those bodies which it held in che- 
mical solution, and thus a variety of crystallized, or primitive rocks, 
were formed. In these we find no vegetable or animal remains, nor 
even any rounded pebbles ; but in the strata which lie upon the crys- 
talline or first deposits, shells and fragments occasionally occur: these, 
therefore, have been termed transition strata; and it is imagined that 
the peopling of the ocean commenced about this period. The waters 
upon the earth began now more rapidly to subside, and finely divided 
particles, resulting from disintegration of the first formations, were its 
principal contents ; these were deposited upon the transition rocks 
chiefly in horizontal layers. They abound in organic remains, and are 
termed by Wernerjloets or secondary rocks. 
It is now conceived that the exposure of the primitive transition and 
secondary rocks to the agencies of wind and weather, and to the turbu- 
lent state of the remaining ocean, produced inequalities of surface, and 
that the water retreated into lowlands and valleys, where a further 
deposition took place, constituting clay, gravel, and other alluvial for- 
mations. 
There are also certain substances which, instead of being found in 
regularly alternating layers over the earth, are met with in very limit- 
ed and occasional patches. Rock-salt, coal basalt, and some other bo- 
dies are of this character, and Werner has called them subordinate for- 
mations. 
Lastly, subterraneous fires have sometimes given birth to peculiar 
and very limited products ; and these are called volcanic rocks. 
Such is Werner’s account of the production of rocks, which he ar- 
ranges under the terms 'primitive, transition, secondary, alluvial, subor- 
dinate, and volcanic formations. A number of nice distinctions and 
accurate minutiae of description attend this theory, which we cannot 
notice in this bird’s-eye view, and which do not affect the general 
conclusions. 
If we examine the stratification of our globe, we shall doubtless find 
that certain substances do occur in a certain order of arrangement, 
and that they appear to have been successively deposited, one upon 
the other, in the manner Werner and his disciples would have us be- 
lieve ; but when we more minutely examine the structure of the 
earth’s surface, and the relations of its different strata, so many incon- 
gruities are discovered, and so much is at variance with their leading 
doctrines, that we are obliged to give them up in favour of views more 
generally applicable. 
2065. Dr. Hutton gives a very different account of the present order 
of things. Looking upon the face of nature, he observes every thing 
in a state of decay ; and as she has obviously provided for the regene- 
ration of animal and vegetable tribes, so the philosophic mind will 
descry, in this apparent destruction of the earth’s surface, the real 
source of its renovation. The lofty mountains exposed to the action of 
the varying temperature of the atmosphere, and the waters of the 
clouds, are by slow degrees suffering constant diminution : their frag- 
ments are dislodged : masses are rolled into the valley, or carried by 
the rushing torrents into rivers, and thence transported to the sea. 
The lower and softer rocks are undergoing similar, but more rapid de- 
struction. The result of all this must be, the accumulation of much 580 
IIUTT#n’s THEORV. 
new matter in the ocean, which will be deposited in horizontal lay- 
ers. Looking at the transition rocks of Werner, he perceives, that 
though not strictly crystalline, they appear made up of finely-divided 
matter, more or less indurated, and sometimes very hard in texture, and 
of a vitreous fracture ; and that this hardening is most perceptible 
when in contact with the inferior rock, which often pervades them in 
veins, or appears to have broken up or luxated tbe superincumbent 
masses. According, then, to Dr. Hutton, the transition or secondary 
rocks of Werner were deposited at the bottom of the ocean in con- 
sequence of operations similar to those which are now active, and 
the primary rocks were formed beneath them by the action of sub- 
terraneous fires ; their crystalline texture, their hardness, their 
shape, and fracture, and the alterations they have produced upon 
their neighbours, are the proofs of the correctness of these views. 
It is by the action of subterraneous fire, then, that rocks have been 
elevated, that strata have been hardened, and that those changes have 
resulted which an examination of the earth’s surface unfolds. The 
production of soils, and of alluvial land, is considered as depending 
upon the same causes as those referred to in the other theory. 
It will be observed that Hutton refers to fire as well as water for the 
production of our present rocks ; the former consolidating, hardening 
and elevating, the latter collecting and depositing the strata. This 
system has been happily illustrated by many of the phenomena that 
occur among the mountains of Scotland, the birth-place of its inventor, 
and the seat of his speculations ; it has been elucidated by the elo- 
quent and philosophic pen of Mr. Playfair ; and has received other ad- 
vantages and aids, which the Wernerian theory has not enjoyed. But 
these circumstances must not be suffered to bias an impartial story ; it 
is to facts we must attend, and upon them found our verdict. 
Much as has been said upon the mischief of geological theories, 
which by some are represented as ingenious, though dangerous, fictions, 
no one can justly deny their importance and utility, as furnishing strong 
incitements to the labour of observation and experiment. He that 
has framed a theory is fond of searching for confirmations and he pro- 
ceeds with a real enthusiasm widely distinct from the cold accuracy of 
the mere accumulator of insulated facts. In all physical inquiries, the- 
ory and observation should go together, like mind and body, the one 
guiding and directing the other. It is quite true that the impartiality 
of an observer may often be affected by system ; but upon this it has 
been justly remarked by Mr. Playfair, that it is a misfortune, agains$ 
which the want of theory is no security. The partialities in favour of 
opinions are not more dangerous than the prejudices against them ; for 
such is the spirit of system, and so naturally do all men’s notions tend 
to reduce themselves into some regular form, that the very belief that 
there can be no theory, becomes a theory itself, and may have no in- 
considerable sway over the mind of an observer. Besides, one man 
may have as much delight in pulling down, as another in building up, 
and may choose to display his dexterity in the one occupation as well 
as in the other. The want of theory, then, does not secure the can- 
dour of an observer, and may greatly diminish his skill. The disci- 
pline best calculated to promote both is a thorough knowledge of the 
methods of inductive investigation, an acquaintance with the history of 
physical discovery, and the study of those sciences in which the rules 
of philosophizing have been most successfully applied. SVCCESSION OP STRATA. 
581 
Section II. Of the Succession of Strata incrusting the Globe, and of the 
Stratification of Britain in particular.—Of Granite, and other pri- 
mary Rocks. 
2066. The terms primitive and secondary rocks, employed in the 
description of Werner’s theory, were introduced into geology by Leh- 
man*, a correct and sensible writer of the middle of the last century. 
He considered the crust of the earth as presenting three distinct series 
of substances. The first, coeval with the world, he calls primitive, 
or primary, rocks. The second series are of more recent formation, 
and seem to have resulted from some great catastrophe, probably the 
deluge, tearing up, and modifying the former order of things ; and the 
third class owe their formation to partial or local revolutions, as indi- 
cated by their structure and situation. 
* Traites de Physique, d'Histoire JVaturelle, de Mincralogie, et de Metallurgies Par J. 
G. Lehman: trnduits de VAllemand. Paris, 1759. “Les montagnes sont des elevations de 
la terre de diffdrentes hauteurs, dont quelques-unes sont composdes de parties dures, solides, 
et pierreuses; d’autres sont composees seulement de parties terreuses; quelques-unes ont dte 
crees en ineme terns que la terre, d’autres ont tt6 formees par des accidens, ou par des eve- 
nemens qui ont eu lieu, en difterens terns.”—Vol. iii. Sect. 3. “ II n’y a rien de plus naturel 
que de partager toutes les montagnes en trois classes. La premifere classe sera celle de mon- 
tagnes qui ont ete formees avec le mondc. La seconde sera celle des montagnes qui ont etd 
formees par unu revolution gendrale qui s’est fait sentir k tout le globe. La troisi&me classe, 
enfin, sera celle de montagnes qui doivent leur formation a des accidens particuliers, ou a des 
revolutions locales.” “ Les montagnes de la premiere classe sont dlevdes, dont quelques-unes 
se trouvent isolees dans des plaines; mais qui, le plus ordinairement, suivent une longue chaine 
et traversent des parties considerables de la terre. Ellcs different des montagnes de la se- 
eonde classe : 1. Par leur elevation et par leur grandeur, qui surpassent celles de toutes les 
autres. 2. Par leur structure interieure. 3. Par les substances ininerales qui s’y trouvent.” 
—Iliid. 
These passages are sufficient to show the merits of Lehman as an original and acute observer, 
and have furnished subsequent geologists with the foundations of their arrangements. 582 
STRATA OF ENGLAND. 
2067. In taking a general view of the substances which incrust our 
globe, for of its nucleus we know nothing, we perceive certain distinc- 
tions of texture and disposition, which are at once curious and import- 
ant. The rocks which I have elsewhere called primitive, or primary, 
are generally found in huge masses or blocks, not regularly stratified*, 
and affecting in their fractures and fissures, a vertical arrangement. 
Sometimes they are of a perfectly homogeneous texture, commonly 
hard and durable, and sometimes composed of two or three ingredients 
blended together ; they are generally crystalline in their texture, and 
usually constitute the loftiest mountains. The transition series of 
rocks of the Wernerian School, or those which they hypothetically 
deem next in point of antiquity to the primitive, are less lofty than the 
former ; they, in many instances, present a slaty texture ; they seem 
to have been deposited in strata or layers, and these are seldom either 
vertical or horizontal, but variously inclined to the horizon. The se- 
condary rocks, or the more recent series, are nearly, if not quite hori- 
zontal in their position. In their texture they are soft, and conse- 
quently easy of decay, and they appear rather as mechanical deposits, 
than as chemical compounds which have resulted from fusion, crystal- 
lization, or solution. The wood-cut at the head of this Chapter may 
serve to give some idea of the relative heights and aspects of these 
three series of rocks. 
These different series are tolerably regularly arranged in regard to 
each other. The primary rocks form the bases upon which the others 
rest; the transition are immediately recumbent upon these ; and these 
are succeeded by the varieties of secondary rocks, and by their de- 
tritus constituting alluvial matter and soils. 
2068. In selecting illustrations from nature of the different geologi- 
cal phasnomena that come before us, I shall in all cases prefer refer- 
ence to our own country ; and I presume that it would, on the whole, 
be difficult to select a better spot for the study of geology than Great 
Britain. We have every variety of rock presented under its various 
aspects ; and though in foreign climes nature may have more liberally 
dispersed the sublime, she has no where more instructively or deli- 
cately diversified the earth’s surface than in the small space allotted to 
the British isles. 
A section of the south of England, from the coast of Cornwall, for 
instance, in the west, to London in the east, will furnish a good exhi- 
bition of the phenomena of stratification to which I have just alluded. 
It will begin at the Land’s-End, with primitive rocks, massive and 
amorphous. Upon this rest several species of transition rocks, espe- 
cially slates of different kinds, having various inclinations ; and these 
are succeeded by secondary strata, deviating more and more from the 
vertical, and acquiring the horizontal position ; and ultimately we at- 
tain the alluvial matter upon which the metropolis stands. It is princi- 
pally clay, and has once perhaps formed the mud at the bottom of a salt- 
water lakef. 
* To this distinctive character there are, however, numerous exceptions; gneiss, mica, slate, 
quartz, rock, and clay slate, exhibiting a distinctly stratified arrangement. 
f Mr. Greenough’s valuable Geological Map of England and Wales, and Mr. Smith’s Geo- 
logical County Maps, will be found very useful to the student; to whom 1 also recommend Mr. 
W. Phillips’ Selection of Facts, &c., as an excellent abridgment of the important materials 
contained in the Geological Transactions. FIELDSPAR. 
Proceeding from London northwards, towards the Scotch border, 
the order of stratification is reversed ; and traversing a highly interest- 
ing series of secondary rocks, we arrive in Cumberland at some of the 
primitive series. The whole arrangement is such as to include the 
highest and oldest rocks upon the west side of England, forming an in- 
terrupted chain extending from the Land’s-End, in Cornwall, to Cum- 
berland, and thence to the northern extremity of Scotland. So that 
the length of Great Britain, and its general shape, appear in a consi- 
derable degree dependant upon this chain of mountainous land, and 
upon two lower ridges, which extend in one direction from Devon- 
shire, through Dorsetshire, Hampshire, and Sussex, into Kent: and in 
another, nearly from the same point, to the east of Yorkshire. 
The western ridge is broken in upon in several places by plains and 
rivers, giving rise to so many chasms in the great chain. 
In the Descriptive Catalogue of the Geological Specimens in the 
Royal Institution*, an attempt has been made to follow the natural suc- 
cession of strata in Britain, and to show their successive alternations ; 
and I trust that it will prove serviceable in connecting the following ob- 
servations with their respective illustrative districts of our island. 
2069. Of the primitive rocksj, one of the most abundant in nature, 
and the most useful in its applications, is Granite, so called from its ap- 
pearing to be made up of a number of distinct grains or particles. Its 
essential component parts are quartz, feldspar, and mica. 
2070. Quartz is the substance commonly called rock-crystal, and 
has already been described (1336). It is sometimes met with in moun- 
tain masses, which usually present a conical appearance. The quartz 
is milk white, and of a more or less granular texture. The Sugar- 
Loaf Mountains near Dublin, the Paps of Jura in Argyleshire, and 
some of the mountains of Sutherland and Caithness, present instances 
of this formation which is stratified in the island of JuraJ. 
2071. Feldspar, the next constituent of granite, is a compound body, 
of which silica and alumina are predominant ingredients ; it generally 
contains a little lime and potassa, and is often coloured by minute por- 
tions of oxide of iron§. Sometimes it is found crystallized, when it 
assumes the form of four and six-sided prisms, bevilled on the extremi- 
ties ; its usual colours are red, white, and grey. It is softer than 
quartz, but harder than glass, and is characteristically marked by fusi- 
bility before the blow-pipe. 
* A Descriptive Catalogue of the British Specimens, deposited in the Geological Collection 
of the Royal Institution. Longman & Co., 1816. 
f In selecting specimens of rocks and strata for the geological cabinet, we should endeavour 
to show their recent fracture, as well as their weather-worn surface, which is generally easily 
attainable. 
| Geological Transactions, ii. 450. 
5 In a fine specimen of pale flesh-red feldspar, from the Alps, crystallized in the form oi 
the oblique four-sided prism, I found the following constituent parts: 
Silica 
. 68.00 
Alumina 
Potassa 
Lime 
2.00 
Oxide of iron 
...... 0.50 
99.00 
Loss ...... 
...... 1. 
100.00 GRANITE. 
Feldspar is a very important ingredient in many kinds of pottery ; 
and the substance used by the Chinese, under the name of petuntz, is 
probably of a similar nature. The decomposing feldspar of Cornwall 
is abundantly employed in the English porcelain manufactories, and as 
it contains no iron, it retains its perfect whiteness. According to Mr. 
Wedgwood, it consists of 
60 alumine 
20 silex 
20 moisture and loss. 
There are some beautiful varieties of feldspar employed in orna- 
mental jewellery, such as the green and blue or Amazon-stone, of Si- 
beria and America ; the foliated,pearly, or resplendent feldspar, call- 
ed adularia and moon-stone ; and the feldspar of the island of St. Paul, 
upon the coast of Labrador, distinguished by the property of reflecting 
very beautiful colours when the light falls upon it in certain directions. 
Feldspar is an important component of several other rocks besides 
granite. 
2072. Mica, the third and last of the essential ingredients of granite, 
is a well-marked compound mineral, consisting principally of alumina 
and silica, with a little magnesia and oxide of iron. Its texture is la- 
mellar, and it is easily split into thin, flexible, elastic, and transparent 
plates. It is so soft as readily to yield to the nail ; it is sometimes 
met with crystallized in four and six-sided plates and prisms. Its usual 
colours are shades of brown and grey ; sometimes it is red, and some- 
times black. In some parts of Siberia mica is copiously quarried, 
and is employed as a substitute for glass in windows and lanterns. It 
has been thus used in Russian ships of war, where it has the advantage 
of not being shattered, like glass, by the discharge of artillery. The 
extreme tenuity of the plates into which it may be divided, and their 
elasticity, renders it very useful for the enclosure of objects to be sub- 
mitted to microscopic inspection. 
2073. Such are the characters of the components of granite ; in 
some specimens of which they may be distinctly traced and separated 
from each other, but sometimes the particles are so small as to produce 
a compound, which to the unaided eye will seem almost homogeneous. 
We have, therefore, fine and coarse-grained granite. The former is 
abundant in Scotland, the latter in Devonshire and Cornwall. Indeed, 
the Cornish granite is remarkable for the well-defined and large crys- 
tals of feldspar which it contains, and which may be seen in many parts 
of London, where this rock has been used for paving, and where the 
crystals of white feldspar have become evident in the mass, from the 
constant attrition to which it has been subjected. It is of this stone 
that the Strand Bridge is mainly constructed. The colour of granite 
is principally dependant upon that of the feldspar it contains, though a 
dark mica will often give it a gloomy hue. It is commonly grey or 
reddish. 
2074. There are two rocks very closely allied to granite, and usual- 
ly associated with it; I mean slaty granite, or gneiss, composed of 
precisely the same materials as granite, but slaty in its fracture, owing 
to the comparatively large quantity of mica it contains ; and the other 
rock is a compound of mica and quartz ; it has a slaty texture, and also 
•derives its leading characters from the large quantity of mica it con- 
tains : it is called mica slate. 2075. On the origin of granite geologists widely differ. As it con- 
stitutes the basis upon which all other rocks appear to lie, Werner 
has regarded it as the first formation of that chaotic rock-depositing 
fluid, in which he imagines the earth once to have been enveloped. 
But many peculiarities of granite have been adduced by Dr. Hutton, 
as contrary to such an opinion. If we examine a granitic district in 
nature, we shall observe, in regard to it, two leading phenomena. The 
one is that veins of granite frequently shoot from the great mass into 
the superincumbent strata. The other, that the bodies lying upon 
granite, especially if they be stratified, either bear evidence of having 
been broken up, dislocated, and penetrated by the granite, whilst in a 
fluid state ; or they seem as if gradually elevated by some power which 
has thrown the granite up from below. So that, upon this view of the 
subject, the date of granite as far as concerns its present position, is 
posterior to that of the strata that rest upon it. They were first de- 
posited, and the granite then erupted from beneath, and elevated the 
other strata, throwing them out of the horizontal, and giving them va- 
rious inclinations to the horizon, or sometimes a vertical position. 
The Brocken Mountain in the Hartz Forest in Germany, St Michael’s 
Mount in Cornwall, and the granitic district at Aviemore in the Scotch 
Highlands, will furnish illustrations of this subject. The first I select 
as being, at the same time, one of the favourite proofs with the Wer- 
nerians of their master’s theory, while the Huttonians may regard it 
no less favourable to the truth of their views. 
Of this mountain the peak is granite, and upon it are regular layers 
of other rocks, the dip or inclination of which is regulated by the sur- 
face of the central granite. In inspecting a section of the Hartz moun- 
tain, it will, I think, hardly be denied, that the appearance is rather in 
favour of the elevation of the strata, by the eruption of the granite, 
than of the original deposition of the granitic nucleus, and the succes- 
sive subsidence of the other strata upon it. 
At St. Michael’s Mount, in Cornwall, a schistose, or slaty, rock, is 
invaded by a mass of granite from beneath ; veins of the latter pene- 
trate the former, which is hardened, and broken, apparently by the 
force with which the granite has been protruded. Indeed, the whole 
granite district of the west of England, beginning at Dartmoor, in De- 
vonshire, and extending to the Land’s End, in Cornwall, presents ap- 
pearances, which are no way so well accounted for as upon that hypo- 
thesis which considers the granite to have been thrown up from below 
in a fused state, and to have forced its way through the superincumbent 
strata. There are four granitic summits in the promontory of Corn- 
wall, all probably connected with each other, and with that at Dart- 
moor ; and the surrounding country is principally clay slate, which 
every where inclines to the granite, in the same manner as the strata of 
the Brocken, in the Hartz Forest. 
In the hill at Aviemore, to which I have alluded, veins of granite are 
seen penetrating the slaty rock in all directions ; and upon the wea- 
ther-worn side, facing the north-east, a large vein of granite may be 
perceived, widest at bottom, running nearly perpendicular, and en- 
larging into a mass, or stratum, of granite, between the schistose 
layers. 
Such, then, is the appearance of granite, and such the arguments of 
the Huttonian geologist concerning its origin. I have mentioned that, 
GRANITE. 
585 586 
GRANITE. 
the superincumbent rocks are frequently penetrated by granite veins, 
and it is obvious that every vein must be of a date posterior to that of 
the body which contains it; and further, as the veins are often observ- 
ed to proceed from the main body of the granite, into the superincum- 
bent strata, it may be argued, that the mass of granite, and the veins pro- 
ceeding from it, are coeval, and both of later formation than the imme- 
diately superincumbent strata. 
Veins of granite, however, are frequently discovered, which cannot 
be traced to any original mass, or mountain ; they seem to be insulat- 
ed, as it were, among other strata. This is the case at Portsoy, and in 
Glentilt; and in some of the Western Isles of Scotland, especially Ti* 
ree and Coll; and is also observed in many parts of Cornwall. £)r. 
Hutton, from collateral evidence, conceives that these are always unit- 
ed to some granitic mass, though too deep, or at too great distance, to 
be traced and discovered 
It may now be asked, how the pupil of Werner accounts for pheno- 
mena of this kind ? I have already said that he regards granite as hav- 
ing been deposited before all other rocks, though its irregularity and 
its general want of stratification are decided objections to such an idea, 
a*d that the other substances were precipitated upon it in the order we 
And them. In these strata, cracks and fissures occurred, and a new 
deposition of granite took place from the chaotic fluid, confined to the 
said cracks and fissures, and producing the appearance of granitic 
veins ; and the hardening of the neighbouring rocks, referred by the 
Huttonians to the heat of the injected granite, is accounted for by the 
infiltration of the aqueous solution, which has, as it were, lapidified the 
softer materials. Now, though we may imagine granite to have been 
in igneous fusion, we cannot easily conceive it susceptible of aqueous 
solution ; and if so dissolved, why should its second deposition have 
been confined to the cracks and fissures ? Why should it not have 
formed a new stratum ? With these facts before us, it is useless to 
enter into further comments, and we can only embrace that hypothesis, 
(for, after all, it is but hypothesis,) which appears best supported by 
evidence derived from actual observation*. 
2071 The aspect of a granite district in nature is subject to varia- 
tion ; it, however, exhibits traits sufficiently peculiar, which are readi- 
ly recognised by the traveller in his approach to it. 
In Cornwall, and in some parts of Ireland, especially in the county of 
Donegal, the granitic rocks are marked by the bold and abrupt precipi- 
ces which they present to the attacks of the ocean ; and by the barren 
and dreary aspect of the inland plains that seem like fields, in which 
blocks of the stone have been torn from their beds, and indiscriminate- 
ly scattered over the moss-grown surface. The elevation of these 
districts is not considerable, the granite is coarse grained, and splits 
into immense blocks, separated from each other by natural seams, and 
appearing like the ruins of edifices constructed by a giant race. In 
* Some have regarded granite as a congeries of crystals of mica, feldspar, and 
accidentally blended and united; the inspection, however, of the rock, clearly proves that all 
its materials have been together in fusion; for we find in some granites the quartz impressed 
by the crystals of feldspar, and in others the feldspar receives impression from the quartz. 
Dr. Hutton has looked upon this as demonstrating the igneous fusion of granite, for, (says Mr. 
Playfair,) “ had the materials been dissolved in water, one kind of crystal ought not to im- 
press another, but each enjoy its own peculiar shape.” This, however, I do not hold to be 
Bound argument. PORPHYRY. 
587 
other cases, granite forms irregular and broken peaks, of prodigious 
elevation, and does not split into the blocks and masses just alluded to. 
This is the case in the Alps and Pyrenees, in the highest Scotch moun- 
tains, in the Hartz, and in the Tyrol. 
In Asia and Africa granite constitutes the Uralian, Altaian, and Hi- 
malayan chains, and the Atlas mountains ; and in South America, the 
lofty ranges of Cordilleras are chiefly of a similar description. The 
wood-cut at the head of this section shows the appearance of the al- 
pine and of the massive granite. The sketch is taken from that of 
Mont Blanc, and of the Land’s-End, in Cornwall. 
2077. Some kinds of granite are prone to decomposition, crumbling 
down into a fine clay containing siliceous particles : this probably arises 
from a peculiarity of the feldspar, afterwards to be noticed. In gene- 
ral, granite is the most durable of nature’s productions, and long re- 
sists the destroying hand of time ; as a building material, therefore, 
granite is almost unrivalled : and, though in common cases its extreme 
hardness is against its employment, its use should be enjoined for pub- 
lic edifices. Dublin furnishes some noble examples of buildings con- 
structed of granite, which is there procured in the immediate vicinity 
of the city, and of a very beautiful kind. 
In Wales there is very little granite ; in the north of Scotland it is 
abundant; and in England it occurs in Cornwall, Devon, Westmore- 
land, and Cumberland. It is also met with in smaller quantities in 
Worcestershire, at the Malvern Hills; and in Leicestershire, in 
Charnwood Forest. 
2078. Although granite probably exists in great abundance below 
the earth’s surface, the quantity visible above ground is comparatively 
small, perhaps not amounting to a hundredth part of the other primi- 
tive and transition rocks.- In some parts of Scotland the granite su- 
perficies, however, is very considerable, and much exceeds the limits 
assigned to it by Dr. Hutton. Upon this subject a very acrimonious 
controversy arose between Dr. Hutton and Mr. Kirwan ; the general 
statements, however, of the former, in this and other cases, commonly 
make much nearer approach to truth than those of the latter ; but as 
human reason is not infallible, he who always contradicts must some- 
times be right, and thus the mere cavilling disputant may occasionally 
discover the errors of the slow and cautious observer of nature. 
2079. To the class of massive unstratified rocks belongs Porphyry, 
a substance which is ranked by Werner among the primitive forma- 
tions. Its essential constituent is feldspar ; and genuine porphyry 
may be defined as massive feldspar, containing embedded crystals of the 
same substance. Any rock including distinct crystals of feldspar, is 
called porphyritic, as porphyritic granite, &c. The colour of porphy- 
ry, which is usually reddish, brown, and green, is principally derived 
from the base, or paste including the crystals. The common aspect 
of porphyry is that of blocks and masses, not very unlike some of the 
varieties of granite, but its fragments are generally smaller, and are in 
a more decaying condition. Porphyry is an extremely durable mate- 
rial for architectural purposes, and as such was highly esteemed among 
the nations of antiquity. It is met with in many parts of Britain : and 
in the north, the porphyry districts are of singular grandeur, as at the 
base of Ben-Cruachan, on the banks of the Awe ; and amidst the pre- 
cipices of Ben-Nevis, the highest of the British mountains, 588 
serpentine. 
The British porphyries are many of them of great beauty, and might 
well be substituted for all ornamental purposes, for the more rare and 
expensive foreign varieties. 
2080. Granitic rocks frequently contain a large proportion of horn- 
blende, a mineral of a greenish black colour, which sometimes forms 
prismatic crystals ; it consists of silica and alumina, with magnesia, and 
appears to derive its colour from oxide of iron, of which it contains 
from 20 to 30 per cent. Hornblende sometimes passes into mica ; and 
if the component parts of the two bodies be compared by analysis, the 
principal difference will often be found to consist in the excess of iron 
in the former. 
These aggregates are termed syenites, or syenitic rocks, and are of 
various hues, according as one or other of the constituents predomi- 
nates. Sometimes the place of the quartz is wholly occupied by horn- 
blende, and the rock is principally an aggregate of feldspar and horn- 
blende. The term syenite is derived from Syene, in Upper Egypt, 
where this rock is plentiful and was used for architectural purposes by 
the Egyptian and Roman sculptors. The aspect of syenitic rocks is 
allied to that of granite and porphyry. They may be observed rising 
from the slaty district of St. David’s in Pembrokeshire ; and in Cum- 
berland, near Wastdale and Buttermere. A beautiful syenite is notic- 
ed by Mr. Bakewell, as occurring in Leicestershire, at Markfield- 
Knowle, a hill on Charnwood Forest. Syenite very often contains 
magnetic oxide of iron. 
2081. Another substance belonging to the class of rocks we are now 
describing, is serpentine ; its appearance is singularly picturesque 
and beautiful; and it forms a delightful contrast to the sublimity of gra- 
nitic districts. Serpentine has its name from the variety of tints which 
it exhibits, such as bright red, green, brown, yellow, and their various 
shades, and it often is prettily traversed by veins of a soft substance, 
to which the term steatite or soapstone has been given (698)*. 
Some of the varieties of serpentine admit of a tolerable polish, and 
such are very desirable for many ornamental purposes. 
Serpentine is seen in Cornwall in characteristic beauty, forming part 
of the Lizard promontory on the southern coast of the county, where 
its general aspect is shown in the following sketch. It appears in va- 
riously shaped and coloured blocks and masses ; it forms natural arches, 
columns, and caves ; and the district is of very singular interest from 
many concomitant circumstances, especially from the blocks of por- 
phyry upon which the serpentine is incumbent, and the veins of granite 
associating with those of steatite, which pervade it. 
* Serpentine has been repeatedly analyzed; but the results are very discordant; no doubt 
owing to the indeterminate nature of the rock. See Jameson’s Mineralogy, 2d. edit., Vol. 
i., p. 509. Its principal constituents appear to be silica, magnesia, oxide of iron, and a little 
carbonate of lime. See the analyses of Serpentine, given above (1410). SERPENTINE. 
Serpentine is met with also in the Isle of Anglesea, upon the north- 
ern coast near the celebrated Parys Mine. Some of the serpentine of 
this district is of more brilliant colours, more hard and translucent 
than the ordinary serpentine ; it belongs to the species called by mi- 
neralogists noble serpentine; the same rock occurs at Portsoy, on the 
Murray Frith in Banffshire, where it is associated with granite. 
The composition of serpentine, as relates to its proximate compo- 
nents, has been variously described. It is generally so fine grained as 
to appear of an uniform texture; but in Cornwall a coarsely aggregat- 
ed rock, consisting of feldspar, talc and schiller spar, may be traced 
passing into the fine-grained serpentine. I have already alluded to 
the nature of feldspar. Talc is a body somewhat resembling mica in 
appearance, but the plates into which it is divisible are not elastic. Its 
usual colours are various shades of green. It consists of nearly equal 
parts of silica and magnesia, with a little lime ; not more than six per 
cent. It is met with in small tabular crystals. 
Schiller stone, or schiller spar, is a term from the Germans, implying 
glistening or changeable spar : it is one of the varieties of diallage of 
the French authors ; it is a silico-ferruginous fossil, containing 
44 silex 
24 iron 
18 alumina 
12 magnesia. 
Its colour is dark green : its usual lustre is semi-metallic, varying ac- 
cording to its position in regard to incident light. 
Steatite is a substance of different tints of grey and green, and from its 
very singular unctuous feel has been called soap-stone. It is somewhat 
abundant in the serpentine of Cornwall, one of the masses of w hich is 
called the soapy rock,; it is here carefully collected for the porcelain 
works of Worcester and Swansea, in which it forms a very important 
ingredient. It also occurs in the serpentine of Banff. According to 
Klaproth, Cornish steatite consists of 590 
MARBLE.. 
Silica 
Magnesia 
Alumina 
9.25 
Iron 
Potassa 
. , . . . 0.75 
Water and loss 
98.75* 
2082. Marble (643) is the last of the roGks belonging to the class 
I am now describing. It is also very abundant in the secondary rocks, 
but its characters are there different. Among primary rocks, marble 
is associated with mica slate, gneiss, serpentine, and quartz rock, and 
it differs from marble belonging to other rocks, in its granularly fo- 
liated texture and in the absence of organic remains. The most es- 
teemed varieties are perfectly white and free from veins ; somewhat 
translucent, and susceptible of a good polish. These marbles are im- 
ported for ornamental purposes, especially for those of the sculptor. 
Nearly all the sublime wrnrks of the Grecian artists were sculptured 
in the marble from the isle of Paros in the Archipellago, and from the 
Pentelic mountain near Athens ; but the marble of Carrara is now in 
highest estimation, and is almost exclusively used by the European 
sculptors of the present day. Of the coloured varieties, that of the 
isle of Tiree is extremely beautiful; it is of a pale red, spotted with 
green hornblende. Marble is found in several parts of Scotland, and 
in some places of characteristic beauty, and alternating within small 
limits, with other rocks. Dr. Mac Culloch, in his Sketch of the Mine- 
ralogy of Sky|, has described several beautiful varieties found in that 
island, and has adverted to the oeconomicaluses to which they are ap- 
plicable. In Inverary park primary marble may be seen in contact 
with mica slate and porphyry. Serpentine and marble are sometimes 
blended together, and they then form a valuable compound for orna- 
mental purposes, which has been called Verd Antique. In the serpen- 
tine of Anglesea, patches of marble are found which much enhance 
its beauty. 
A very remarkable marble quarry is that of Icolmkil, or Iona. 
Gneiss rocks constitute the leading feature of this island, but at the 
south-west point is a bed of marble, about 40 feet wide bounded by 
vertical walls of hornblende rocksf. Near it is a mass of hornstone, 
and above the whole protrudes an immense vein of granite, surrounded 
* Vide Klaproth’s Beitrage, V. Band, S. 24. 
f Geological Transactions, iii. p. 1. 
I The marble is of the species called dolomite (698), distinguished from the true primary 
marble or granular lime-stone, by the tardy effervescence excited by pouring muriatic acid 
upon it, and by its containing magnesia; it is also finer grained, and its fracture more splin- 
tery, than that of common marble. The dolomite of Iona yielded to Mr. Tennant, 
Carbonic acid 48.82 
Lime 31.12 
Magnesia 17.06 
Insoluble matter 4.00 
Phil. Trans. 1799. 
The dolomite of the Apennines yielded to Klaproth, 
Carbonate of lime 65 
Carbonate of magnesia ........... 35 
Beitrage, B. 4, S. 215. Height op primitive mountains. 
by the marble, but from which it has been loosened, so as just to admit 
a person to pass between the two walls. That they have once been 
in contact, is proved by the granitic protuberances having correspon- 
dent indentations in the marble, and vice versd. 
2083. We have now considered a highly important series of rocks, 
and have enumerated their characters as insulated individuals. As a 
class they present analogies which distinguish them from their super- 
incumbent neighbours, and give them the stamp of a peculiar and dis- 
tinct formation, either formed before organic beings, or under circum- 
stances which have destroyed such remains. 
In these rocks we seldom observe any regular stratification ; they 
are mostly constituted of amorphous, irregular, and various masses, 
and present no appearances of having been deposited from water. 
They are crystalline aggregates ; and they are deeper in their situa- 
tion than other rocks, which always appear incumbent upon them, and 
often elevated or heaved, as it were, by their operation. 
They often break through the beds, or layers, that cover them, and 
rise to a very great elevation, forming the summits and peaks of the 
loftiest mountains. In England they are comparatively rare ; in Corn- 
wall there is abundance of granite, but it rises to no great height. 
Granite and its associates are found in Cumberland, but they are spa- 
ringly scattered over the county ; and the romantic and picturesque 
aspect of the hills is chiefly derived from other species of rocks. In 
Wales, the primary rocks are uncommon, and I know of no granite ; 
but there is a portion to be found in the centre of Anglesea, near 
Gwindy, wrhere its associations merit notice. 
In Scotland, the districts composed of primitive rocks, and present- 
ing their various aspects, junctions, and transitions, are full of grandeur 
and interest. Travelling northwards from Edinburgh, we enter upon 
mica slate at one of the Highland passes, and crossing the Grampians, 
find their principal summits of the same materials. From Loch-Tay 
to Killin the same rocks continue, with beds of limestone. Ben-More 
is a mica slate rock, of exceeding grandeur : it rises to about 4000 feet 
above the sea’s level, and is thickly intersected with quartz veins. 
Ben-Lawers, to the North of Loch-Tay, is of similar composition ; it 
is chiefly gneiss, associated wfith mica slate and quartz ; and the same 
substances are found at Crag-Caillach, and Schehallion, and contribute 
to the magnificence of the celebrated pass of Killikrankie, between 
Dunkeld and Blair in Athol. 
I have thus represented the highest mountains in Britain as compos- 
ed of granite and its associates ; but these are mere trifling protube- 
rances upon the earth’s face, when compared with the exceeding 
heights of the Alpine chain, or the yet more elevated mountains of 
South America, and of Asia, which consist of the same materials. Ben- 
Nevis, the loftiest of the British mountains, is situated in the south of 
Inverness-shire, and is 4370 feet high. Cairngorm in the same coun- 
ty, is 4050 feet high. Mont Blanc, in Switzerland, has its peak elevat- 
ed 15,600 feet above the level of the sea; it is the highest mountain 
of Europe ; Chimboraso, the highest summit of the Andes, is 20,280 
feet above the sea’s level; many of the peaks of the Himalaya chain 
are as high, and the loftiest appears to exceed 25,000 feet*. 
* See an article on this subject in the sixth Volume of the Quarterly Journal of Science 
and the Arts, p. 55. 592 
GRANITE BOULDERS. 
The reason why these excessive elevations present nothing but pri- 
mitive rocks, and especially granite, (excepting, indeed, where they are 
volcanic) may not at first appear quite obvious, for in the low lands the 
primitive are generally covered by secondary strata, which were also 
once probably incumbent upon their loftiest summits. It is likely that 
the destructive agencies of the elements have been so powerfully ex- 
erted in these elevated and unprotected regions, that the secondary 
rocks have yielded to their unceasing attacks, and have been carried 
towards the valleys by the rills and torrents, while granite and its du- 
rable accompaniments have more obstinately opposed the inroads of 
such resistless assailants. 
2084. At the same time, however, it will seem probable that the 
granitic mountains have themselves suffered tremendous degradation, 
and that at a former period their summits were beyond their present 
elevation. All this will appear more clear when the general charac- 
ters of mountain chains, and the phenomena of their decay, are taken 
into the account. But several circumstances present themselves to 
the most superficial observer, which in a language that it is impossible 
to misinterpret, announce the influence of fdestructive agents upon 
these apparently invulnerable materials. Prodigious masses of gra- 
nite are often found among the secondary strata that form the valleys 
under primary mountain chains ; they are insulated and unconnected 
with any general mass of the same material; and the more distant they 
are from the granite range, the more they are rounded and smoothened 
upon the surface. Of this description are the boulders, or blocks of 
granite, observed by Saussure upon the east side of the lake of Gene- 
va. One of these, called Pierre de Goute, is ten feet high, with an 
horizontal section of 15 feet by 20. In the valley of Chamouny, se- 
veral similar blocks have fallen from the Aiguilles. Some of these 
have been transported between 30 and 40 miles, and as several moun- 
tains and valleys are now interposed, their transportation must have 
taken place at a very remote date*. 
In the glen which separates the Great from the Little Saleve, there 
are many granite boulder stones strewed over a calcareous plain ; and 
of these several are supported upon a short pillar of limestone, result- 
ing from the protection afforded to the calcareous rocks by the harder 
boulder, so that the height of the column becomes a measure of the 
wearing away of the surrounding country. This appearance has in- 
duced Saussure to assert, that these stones are now in the very situa- 
tion where they were left bjr the gi’eat aqueous torrent, or debacle, 
which tore them from their original bed, and brought them down from 
the high Alps ; a conclusion, how ever, as Mr. Playfair has remarked, 
not altogether warranted by the fact. In some of the recesses of the 
the Jura there are large, and somewhat angular, blocks of granite 
which have evidently been deposited in their present situations at ve- 
ry remote periods, the surrounding and impending heights being com- 
posed of limestone rocks, which form an ampitheatre round the pre- 
sent valleys. In the neighbourhood of Neufchatel, too, there is an 
enormous insulated mass of granite : it is as large as the celebrated 
* See Dr. Kidd's Geological Essay, Chapter, xviii., which contains an account of the 
most remarkable boulders. DECOMPOSING GRANITE. 
593 
foundation of the statue of Peter the Great, erected at Petersburgh 
by Catherine II., which is composed of a boulder, or detached block 
of granite, found in the bay of the Gulf of Finland, whence it was 
transported to the capital; its length was 42 feet, its breadth 27 feet, 
its heighth 21 feet*. 
In the Isle of Arran, an immense block of granite is found upon 
the shore, not only three miles from the nearest granite rock, but hav- 
ing also a bay of the sea intervening ; and several similar instances 
might be adduced, proving the great ravages that have been committed 
upon even so hard and unyielding a body as granite. We shall not, 
then, be suprised that the same agents, acting upon softer materials, 
have made more successful depredations ; and have, in many instances, 
completely denuded those granitic surfaces, which were oncg‘ clothed 
by secondary strata. 
2085. In Cornwall, granite is sometimes of very rapid decomposi- 
tion, and the streams which traverse these districts deposit a finely-di- 
vided earthy matter, resulting principally from the feldspar, and much 
used in the potteries. Carglaise tin mine is situated in a decomposing 
granite of this kind, and presents a spectacle highly worthy the atten- 
tion of the curious. The mine is a vast chasm in the granite rocks 
and exposed to the day. The tin ore and shorl rock traverse it in 
abundant veins, and the surrounding peaks strongly remind the behold- 
er of a miniature representation, or model of the Alps. Possibly 
the rapid decay of the granite here depends upon the quantity of al- 
cali contained in its feldspar. 
Dr. Mac Culloch, in a dissertation on the granite Tors of Cornwall, 
published in the Geological Transactions, has made some interesting 
remarks upon the peculiarities which they present, and which have 
given rise to much idle and ignorant speculation. A very remarkable 
Tor is the Cheese-wring, upon an eminence near Liskeard. It is a 
cairn consisting of five stones, of which the upper ones are larger than 
and overhang the lower, the whole pile being 15 feet high. The 
stones of which it consists are yielding to the weather most rapidly at 
their angles and edges ; they are thus becoming rounded, and approach- 
ing that tottering state which will soon hurry them down the precipice 
to their former companions in the plains below. 
This tendency of square blocks of stone to become spherical, inde- 
pendent of friction, is productive, in other cases, of very curious con- 
sequences, and has often been considered as demonstrating the agency 
of streams or currents, by which the masses have been transported 
from distant regions. The present Tor has, by some antiquarians, 
been considered as a druidical statue of Saturn. The same cause ap- 
pears to have produced the celebrated Logging-stone. 
2086. Before we quit the subject of primary rocks, it will be right 
to mention a district of Britain, which, for grandeur of scenery and 
geological interest, can, I think, scarcely be surpassed. I allude to 
the country between the eastern extremity of Loch-Ness and Fort- 
George, and especially to the rocks over which the river Fyers pur- 
sues its turbulent and winding course. 
These are seen in characteristic grandeur in the neighbourhood of 
* See the Relation, par le Comte Marin Carburi de Ceffalonia, &c. Paris, 1777 594 
GRANITIC BRECCIA. 
the small inn called the General’s-hut, and the scenery becomes more 
and more impressive and interesting until we arrive at the celebrated 
falls of the river. I should call the rock a granitic breccia, or conglo- 
merate ; it appears made up of numerous angular fragments of granitic 
materials, held together by a siliceous cement, and the aggregate is of 
extreme hardness and durability ; masses resembling jasper and agate 
may also be observed in it. Dr. Garnet compares the cement, or basis 
of the rock, to a lava of a reddish hue; and a common observer 
would consider the whole as fragments of granite which had been 
united by semi-fusion, or softened and glued together, as it were in the 
fire. The general aspect of the surrounding scenery is such as to im- 
press the mind with the idea of some vast convulsion of nature having 
torn the rocks asunder, and shattered them into gigantic fragments ; 
rugged crags and abrupt precipices present themselves on all sides, 
and the river rushes with tremendous impetuosity through deep and 
obstructed chasms. A rude bridge is thrown over the upper fall, 
whence the spectator beholds the waters of the Fyers, at the distance 
of 200 feet beneath him, rushing into a cavity of 70 feet in depth, 
whence they again emerge in perfect stillness, and, running over an 
uneven and fragmented channel, approach the lower or grand fall. 
Here the waters, previously pent up and exasperated, suddenly dis- 
charge all their violence, and are lost in a deep abyss. The depth of 
the chasm in which the river flows is 400 feet, and it bursts forth in an 
unbroken stream, constituting a fall of 212 feet perpendicular height. 
The rugged irregularities of this district, the fragments that lie thickly 
strewed upon the sides of its mountains, the caverns that abound in 
its rocks, and the perpendicular precipice of the great cascade, consi- 
dered conjointly with the peculiar texture and composition of the ma- 
terials that form it, present many objects worthy the attention of some 
geologist, and may be regarded as recording some great natural convul- 
sion, which has not only broken up and reunited certain primary rocks, 
but has again disturbed their tranquillity, and thrown them into the stu - 
pendous confusion they now exhibit. HEIGHT OF SECONDARY ROCKS. 
595 
Section III. Of Stratified Rocks, and of the Transition and Secondary 
Formations of Werner.—Rock-salt, Coal, Alluvial Matters, Basalt. 
2087. We now descend from the primitive, to the transition rocks 
of Werner; these are more particularly the stratified rocks of the Hutto- 
nian geologists, and they are distinguished by several well-marked 
characters from the unstratified and primary rocks. 
One leading and general circumstance may be observed in regard to 
them, which is, that they never attain the great elevation of the pri- 
mary bodies ; this has been elsewhere referred to the comparative 
readiness with which they yield to the assaults of decomposition and 
disintegration. 
The highest known mountains in the world are those of Thibet, 
constituting the Himalayan chain. They are alluded to by Col. 
Kirkpatrick, in his History of Nepaul, and an extended and interesting 
account of them has been published by Mr. Colebrooke, in the Asiatic 
Researches, Vol. xii. 
Of this chain, the highest peak, covered with eternal snow, is called 
Dvvawala-giri, or White Mountain ; it is the Mont-Blanc of the In- 
dian Alps, and rises to the astonishing altitude of 26,462 feet above the 
level of the plains of Gorakh’pfir; or, upon the lowest computation, 
26,862 feet above the level of the ocean. This is about 6000 feet 
higher than Chimboraso, 11,000 feet higher than Mont-Blanc, and 
22,000 feet higher than the most elevated peak of the British domi- 
nions, which, indeed, makes Ben-Nevis seem very insignificant, though 
its summit is close upon the verge of perpetual snow in this climate. 
There can be no doubt that the lofty peaks of the Thibet chain are 
granite, though we learn that the hills which border them are secon- 
dary, and contain remains of spiral shells. The elevation of secondary 
rocks will, in a great measure depend upon that of the primary mate- 
rials beneath them; thus, in the Andes they attain 12,000 feet, in the 
Alps 7000, and in this country not more than 3500. 596 
STRUCTURE OF SECONDARY ROCKS. 
2088. In respect to the original formation of secondary rocks, the 
notions of the Wernerians and Huttonians are not so widely different 
as we have found them formerly ; they both agree that they are depo- 
sitions from water ; but how, then, have they lost their necessary ho- 
rizontality, and acquired positions more or less inclined, or even some- 
times vertical ? Dr. Hutton conceived they were elevated and har- 
dened by the throwing up of the primary or unstratified rocks from 
below, in the state of igneous fusion. It was once a great difficulty to 
imagine a combustible which should thus furnish fuel to melt these im- 
mense masses of primary materials, and to conceive the real cause of 
that expansive power of heat which Dr. Hutton always flies to. But 
the discoveries of Sir H. Davy, concerning the true nature of earthy 
bodies, have furnished unexpected evidence in defence of these ap- 
parent incongruities of the Huttonian doctrines, and it is bestowing no 
small praise upon a theory, to allow that it is strengthened by the pro- 
gress of knowledge, and elucidated by the advances of experimental 
research. However, that these elevating powers do exist, is proved 
by the sudden throwing up of a hill in the bay of Naples, which was 
raised 1000 feet in a single night*, and by the appearance of anew is- 
land at the Azores, in water between 30 and 60 fathoms deepj. We 
must afterwards refer to the cause of these phaenomina. At present 
possession of the fact is the main requisite. In the Neptunian system, 
it is conceived that the position of the strata has depended upon the 
ground they have been deposited upon, and that they have partly crys- 
tallized, and partly subsided, upon the inclined, or nearly vertical, 
sides of primary rocks ; or that the falling in of caverns has occasion- 
ed their present irregularities ; but, when we observe the mischief 
which the primary rocks seem to have done the secondary, and when 
we take into the account all the phenomena of granite veins, before 
discussed, 1 think that he who is not unduly biassed, will feel inclined 
to acquiesce in the Huttonian interpretation. It is probable, then, that 
the materials of the transition rocks, or, as I would rather put it, of 
those secondary and stratified rocks which are immediately incumbent 
upon the unstratified primitive rocks, are derived from the destruction 
of a former order of things ; that they have been delivered into the 
ocean by the rivers, that they have covered the bottom of the sea, and 
have been hardened, elevated, and traversed by the eruption of gra- 
nitic and other substances belonging to that class, from the bowels of 
the earth. 
2089. The next peculiarity of the secondary rocks that presents 
itself, is their containing fragments, pebbles, and organic remains; 
whence cosmogonists have framed sundry conclusions concerning the 
particular period of their formation, which it will be unwise and use- 
less here to discuss. At the same time, the presence of bodies which 
once belonged to the organized kingdoms, but which, although still re- 
taining their original forms, are completely fossilized, furnishes us with 
many interesting conclusions, and holds out to the inquisitive unfailing 
matter of useful discussion. In the oldest secondary rocks fragments 
are often found, and rounded pebbles, whence we learn their origin 
from former rocks. Upon these, beds occur which contain remains 
* See Sir W. Hamilton’s account, in the Philosophical Transactions, 1771. ' 
t Philosophical Transactions, 1812. See Dr. Kidd’s Essay, Chap. xxvi-. CLAY-SLATE, 
597 
of shells, corals, and fish, all of marine origin, and oftentimes the races 
are extinct. Approaching the newer rocks, relics of quadrupeds, now 
no longer known, are observed ; and, following the deposition of stra- 
ta, we ultimately arrive at remains of lizards, crocodiles, elephants, 
deer, and some other animals; and we occasionally discover districts 
containing land and sea-shells in alternating layers. 
I merely make allusion to these facts, to show how curious and tew 
is the field of inquiry, which modern geology has opened. It has ta'tight 
us that whole races of animals have been swept from the earth’s sur- 
face ; that not only species, but likewise genera, have become extinct; 
that fresh water and dry land existed before the formation of many of 
our secondary strata ; that oviparous quadrupeds began to exist along 
with fish, nearly at the commencement of the secondary formations ; 
that mammiferous sea animals are of more ancient formation than land 
animals ; that a few of those now known, existed towards the termina- 
tion of secondary formations, but that by far the greater number are 
of later date, and probably contemporary with the present order of 
the earth’s surface, for their bones are only discovered in very recent 
depositions, and are in a state of inferior preservation to those of more 
ancient date ; and, lastly, it is to be observed that no fossil human re- 
mains have yet been found. 
Such are some of the topics which this part of geology presents for 
consideration, and which show us that the earth is indeed “ as a book, 
in which men may read strange matters.” Though the existence of 
fossil remains must have been noticed from the earliest ages, the philo- 
sophical discussions to which they have given rise are of very modern 
date, and the merit of fixing the geologist’s attention upon them, as 
recording certain revolutions of the globe, belongs chiefly to Cuvier. 
Further, to promote attention to the nature and arrangement of the 
secondary rocks, it may be suggested that they are the chief reposito- 
ries of metallic substances ; and that, by their decomposition and de- 
cay they furnish the principal materials of the soil in which the vege- 
table has its habitation, and consequently upon which the existence of 
animals ultimately depends. 
2090. Of the secondary rocks, Clay-slate may be first noticed ; it 
is extremely abundant, and generally immediately incumbent upon the 
primary series. It is often micaceous near the junction, and we fre- 
quently observe it fragmented, and penetrated by quartz, or feldspar, 
or mica, or by granite itself. Before the blow-pipe, it fuses into a 
black mass ; its usual colours are various shades of grey, and it is ge- 
nerally so soft as to yield to the nail. Siliceous and argillaceous 
earths, and oxide of iron, with a little lime and magnesia, are its prin- 
cipal ingredients*. The varieties of slate are applied to various useful 
purposes : that which is easily separable into thin plates, compact, so- 
norous, and not injured by the application of a moderate heat, is em- 
* I obtained, as the results of the analysis of a specimen from Luss, near Dumbarton, 
the following component parts: 
Silica 
Alumina 
28 
Magnesia 
5 
Lime 
2.5 
Oxide of iron 
10 
Loss . 
6.5 
100.0 598 
ployed for roofing houses. London is chiefly supplied from Bangor, 
in Caernarvonshire ; and from the neighbourhood of Kendal, in West- 
moreland ; there are also very large quarries at Easdale, in Argyleshire ; 
according to Mr. Jameson, five millions of slates are there annually 
manufactured, which gives employment to 300 men. There are se- 
veral slate quarries of note in Dumbartonshire ; one ought particular- 
ly to be mentioned, at Luss ; it is of geological interest, and commands 
a captivating view of the lake, and the neighbouring mountains. Here 
the clay-slate rests upon mica slate ; the former is of a purplish tint pe- 
netrated by veins of pink carbonate of lime, and of quartz ; the latter 
is very remarkably contorted 
2091. Other varieties of clay-slate are used for writing-slates, slate- 
pencil, fyc.; and where slate is very abundant, we observe it employ- 
ed for monumental tablets, pavements, and walls. Crystals of iron 
pyrites, and some other extraneous bodies are not rare in slate ; 
generally render it unfit for the applications I have alluded to. Slate 
often contains fragments of other rocks, embedded masses, and nodules 
of various kinds, frequently pebbles, and occasionally a few impres- 
sions of shells ; it also often derives a green colour from the presence 
of a mineral called chlorite, consisting of oxide of iron united to siliceous 
and aluminous earths. The slates containing embedded matters are 
called grauwacke-slates, or, when of a less slaty fracture, simply grau- 
wacke, a substance which is abundant in this country. 
2092. The slate district of England is of considerable extent, and 
neither wants sublimity nor grandeur; it follows the great primary 
chain which I before alluded to, as running north and south upon the 
west side of England ; in Cornwall the slate is seen immediately incum- 
bent upon granite, and the slaty districts form very beautiful scenery 
upon many parts of the coast. The term killas has been applied to it 
by the miners. Nothing, I think, can exceed the scenery about Looe, 
Fowey, and the country between it and Falmouth, and upon the north 
coast Tintagell is yet more remarkable. 
There is some grauwacke in many parts of Cornwall. The best 
marked specimens I have seen, are from Mawnan, near Falmouth, 
where it alternates with clay slate. 
2093. The slate district of Wales is of singular interest and magni- 
ficence, as those will acknowledge who have visited the chain of moun- 
tains, including Snowdon, Plynlimmon, and Cader Idris. These 
mountains attain an elevation of betwen 3000 and 4000 feet, their sum- 
mits are jagged and irregular, their declivities steep and barren, and 
the neighbouring passes and valleys have all the peculiarities that slate 
confers ; among them, the Dell of Aberglaslyn, viewed from the bridge 
which unites Merionethshire to the country of Caernarvon, presents a 
grand and awful feature. The rocks are lofty, lonesome, and black ; 
their sides exhibit terrific and inacessible precipices; or where the 
slopes are more gentle, they are covered with the sharp angular frag- 
ments, which time and the elements have dislodged from above. The 
wood-cut at the head of this Section shows the character of the clay- 
slate upon the coast of North Wales. 
Advancing northwards, the mountain chain is broken by the lowlands 
of Lancashire; but in Westmoreland and Cumberland slate again pre- 
sents itself, plentifully accompanied by grauwacke, which contributes 
to the enchanting scenery of the lakes. As black peaks and precipi- 
SCENERY OF NORTH WALES. MOUNTAIN LIMESTONE. 
599 
ces strewed with slippery and cutting fragments mark the mountains of 
common slate, so have the grauwacke rocks peculiarities by which they 
are recognised, and which are no where more evident than in the 
rounded summits that embosom Derwentwater, as represented in the 
annexed cut. In their forms, tints, and outlines, there is something 
indescribably delightful, and they present that rare union of the sub- 
lime and beautiful, of which no better idea can be formed, than that 
suggested by Mr. Burke’s comparison : “ Sublime objects are vast in 
their dimensions ; beautiful ones comparatively small; beauty should 
be smooth and polished; the great, rugged and negligent; beauty 
should shun the right line, yet deviate from it insensibly ; the great, 
in many cases loves the right line, and when it deviates, it often makes 
a strong deviation ; beauty should not be obscure ; the great ought to 
be dark and gloomy ; beauty should be light and delicate ; the great 
ought to be solid and even massive.” These qualities of that which 
is sublime, well apply to the rocks I have before described, and, when 
blended with the parallel definition of the beautiful, furnish a just notion 
of the aspect of those now under consideration. 
2094. The varieties of mountain limestone (the transition lime- 
stones of the Wernerians) are the substances that next occur. They 
are frequently seen immediately incumbent upon clay-slate, and are fur- 
ther distinguished from primitive limestone, or statuary marble, by hav- 
ing a less decidedly crystalline texture. Where this rock lies directly 
upon slate, it contains few organic remains ; but where red sandstone is 
interposed between it and the slate-rocks, or in proportion as it is distant 
from the primary and slate-rocks, the relics of organization become more 
frequent. It then abounds in remains of corals and zoophytes, which 
now are not known to exist. It often is traversed by veins of calcareous 
spar, and presents a great variety of colours. It is abundant in Devon- 
shire, South Wales, Derbyshire, and Yorkshire. At Plymouth this 
rock is seen immediately incumbent upon slate, in a quarry between 
the Dock and the Town. Its colours are red and grey, streaked with 600 
aspect of mountain limestone. 
white crystalline veins. It is also seen to great perfection in the 
Breakwater quarries at Oreston. 
2095. Slate districts often present very curious inflexions and incur- 
vations of their strata. The slate at Plymouth, and the grauwacke of 
Clovelly in the north of Devon, and the killas upon the coast of Corn- 
wall near Charlestown, are in many places very singularly contorted ; 
and sometimes small undulations present themselves in the lamina?, ex- 
actly resembling those left by the ebbing tide upon a gently reclining 
sand-bank. These appearances may, perhaps, be referred to the ac- 
tion of water upon the materials before they were consolidated. 
2096. Limestone strata are also very remarkable for the inflexions 
and curvatures, referred, not very satisfactorily, by Dr. Hutton to 
their having been in a soft state at the time they were disturbed from 
their horizontal position. There are some very curious instances of 
these curvatures noticed by Saussure ; one, in particular, on the road 
from Geneva to Chamouny, where the small stream of JVant D'Arpenay 
forms a cascade by falling over a perpendicular surface of limestone 
rock ; the strata are bent into regular arches, with the concavity to 
the left; while in another neighbouring mountain they turn to the 
right; so that a verticle section of the two would present the figure of 
S. The top of Benlawers in Perthshire, and the coast of Berwick- 
shire, with many other districts in Scotland, present instances of these 
singular contortions. Dr. Hutton has given a plate of the bent strata 
in Berwickshire, from a drawing made by Sir James Hall. I cannot 
here follow Dr. Hutton and his sagacious commentator through their 
arguments founded upon these phenomena, they attempt to prove that 
the undulated strata have received their peculiarities upon level 
ground ; that they have then been elevated, hardened, and often bent 
and contorted during these processes ; and that their irregularities as 
to position, and their fractures and dislocations have thus occured, and 
do not result, as the opposite school would have it, from the falling in 
of caverns,—a position which they assume as at once accounting for 
such appearances, and for the retreat of the ocean. Hutton considers 
the land to have been raised, Werner supposes the waters to have re- 
treated. 
2097. The aspect of a country of mountain limestone is peculiar, 
and generally extremely picturesque. The hills, which, in this coun- 
try at least, are not very lofty, abound in precipices, caverns, and 
chasms ; and, when upon the coast, form small promontories, and jut 
out in low but grotesque pillars. The even surfaces are covered with 
a stinted turf, but the rifts and cracks contain often a soft rich soil in 
which stately timber trees flourish. The chasms of limestone rocks 
are often filled with a fine clay, which has, perhaps, sometimes been 
derived from the decomposition of shaly strata, or sometimes deposit- 
ed from other causes in the fissures, and the singularities of aspect, 
and much of the beauty of this rock, is referable to these peculiarities. 
Thus, upon the banks of the Wye, large and luxuriant trees grace the 
abrupt precipices, and jut forth from what appears a solid rock. Their 
roots are firmly attached in some crevice filled with a favourable soil. 
Sometimes rivers force their way through the chasms ; at other times 
they are empty, and the roofs ornamented by nature’s hand with 
stalactitical concretions of white and glistening spar, which seem like 
the fretted sculpture of Gothic architecture. SCENERY OF DERBYSHIRE, 
601 
The views of Dovedale, and of Matlock and its vicinity ; and the 
caves of Castleton, are admirably illustrative of the scenery of moun- 
tain limestone. Pont-Neath Vaughn, in Glamorganshire, is full of its 
beauties ; and the panorama of Swansea Bay, seen from the Mumbles 
Point, furnishes a pleasing, characteristic, and perhaps unrivalled, 
prospect of these rocks. 
The banks of the Avon too, in the vicinity of Chepstow, are of 
mountain limestone. The rock is there impregnated with bitumen, 
and hence exhales a peculiar and fetid odour when submitted to the 
blows of the axe or hammer. This is by no means uncommonly the 
ease where the limestone rock, as in the present instance, is in the vi- 
cinity of coal. The following sketch may serve to give some idea of 
the appearance of the mountain limestone of Dovedale, in Derbyshire. 
2098. Mountain limestone is an excellent material for building, and 
many of its varieties are sufficiently indurated to receive a good polish, 
and are thus employed for ornamental purposes, being cut into vases, 
chimney-pieces, and the like. Where they abound in corals, and other 
organic remains, these frequently add to their beauty. 
The colours of transition limestone are various, but its essential 
constituent part is always carbonate of lime. The black variety known 
under the name of Lucullite*, or black marble, has long been admired, 
and is often tastefully manufactured and ornamented by etching upon 
its surface. It is found in Derbyshire, Sutherlandshire, and Galloway, 
and appears to derive its colour from carbonaceous matter. 
All these limestones are converted into a more or less pure quick lime 
by the operation of a red heat, and are thus often valuable as affording 
manures, and for other purposes. 
2099. The next rock that occurs in point of succession, is red 
sandstone. It often rests upon slate, and then, from its position has 
* A name given to the marble in consequence of the admiration bestowed upon it by Lu* 
cius Lucullus. Vide Plinii Hist. Nat., 36. 8. 602 
NEW RED SANDSTONE. 
acquired the term of old red sandstone. But a similar substance, or 
nearly so, also is found lying upon mountain limestone, in which case 
it has been called red marl, or new red sandstone. 
Entering upon this substance, we come upon distinctly stratified 
ground ; it is very abundant in England, especially in Lancashire, 
Cheshire, Staffordshire, Shropshire, and Worcestershire ; and indepen- 
dent of its embowelled treasures, for it is connected with coal and rock 
salt, its surface is generally favourable to vegetation, and its soil suffi- 
ciently luxuriant. It consists principally of siliceous particles, and 
oxide of iron, with some argillaceous earth, and more or less calcare- 
ous matter; Its beds are often of great thickness, as may be seen in 
the quarries ; it is much used as a building stone, but moulders in conse- 
quence of the action of air and moisture upon the oxide of iron. It of- 
ten contains particles of mica, and fragments and pebbles of old rocks. 
3000. Red sandstone rocks are seen in some parts of Britain in great 
beauty and perfection, especially where they occur on the coast, or 
are intersected by rivers. At Ilfracomb, the old red sandstone of the 
Somersetshire coast is seen lying upon slate ; and the junction is inte- 
resting to the geologist, the sandstone becoming somewhat slaty, and the 
slate having a tendency to a granular fracture. The following sketch 
of Hawthornden, near Edinburgh, shows the characteristic features of 
the red marl rock, or newer red sandstone ; and the ancient castle, 
with its dungeons and vaults, is constructed of this material. Ridges 
of red sandstone, containing mica and fragments, sometimes accompany 
primary rocks, of which a very singular instance occurs upon the banks 
of Loch-Beauly, near Inverness ; a high range of granite is there bor- 
dered by a breccia, very like that of the bed of the Fyers ; and a low 
ridge of red sandstone, of which the valley is also composed, accom- 
panies the series, and seems the detritus of the more ancient and lofty 
formations. 
3001. The slates, grauwackes, and limestones, are in this country 
the principal seats of the metallic ores ; and they form scenery which, ROCK SALT. 
603 
gradually decreasing in grandeur and sublimity, increases in softness, 
variety, and luxuriance. In the lowest sandstone formation, we meet 
with a variety of bodies of the utmost importance in our arts and ma- 
nufactures. 
3002. A substance which occurs in abundance in many parts of the 
red strata, is gypsum or sulphate of lime, known also under the name of 
plaster-stone, selenite, and alabaster. Near Tutbury in Staffordshire, 
and near Nottingham, it is found in blocks and veins ; and lately a va- 
riety, new in England, has been found, called Anhydrite. These mine- 
rals constitute valuable materials for the ornamental manufactures of 
Derbyshire. 
3003. In the county of Cheshire the red sandstone contains immense 
beds of common salt, most abundant in the valley of the Weaver, and 
near Middlewich, Northwich, and Nantwich ; itis accompanied by gyp- 
sum. The first stratum was discovered about 150 years ago, in search- 
ing for coal. It begins about 30 yards from the surface, and is 25 yards 
thick ; below this, and separated from it by 10 or 12 yards of indurated 
clay, is another bed of salt, the extent of which is unknown ; in many 
places it is nearly pure, in others tinged with oxide of iron and clay. 
This pit is at Northwich ; and at other places there are very abundant 
brine springs. A most remarkable circumstance in the Northwich mine 
is the arrangment of the salt, giving rise to an appearance something 
like a mosaic roof and pavement, where it has been horizontally cut. 
The salt is compact, but it is arranged in rounded masses, five or six 
feet in diameter, not truly spherical, but each compressed by those that 
surround it, so as to have the shape of an irregular polyedron. The 
Wernerians regard the salt as having merely crystallized here from its 
aqueous solutions ; the Huttonians consider the water to have been 
evaporated by heat. The large pit at Northwich presents a very sin- 
gular spectacle when duly illuminated ; it is a circle of nearly two miles 
in circumference, the roof is supported by massive pillars of salt, and 
the effect is heightened by the variety of colours it presents*. 
3004. Coal is the most important product of these middle strata. 
What is called a coal field, or district, or sometimes a coal basin, may 
be regarded as a concavity, varying greatly in extent, from a few to many 
miles, and containing numerous strata or seams of coal of very various 
thickness, alternating with sandstone, clays, and soft slate or shale con- 
taining impressions of vegetables and sometimes the remains of fresh 
water shell-fish. The parallelism of these strata is generally well pre- 
served. The whole arrangement is seldom any where quite horizon- 
tal, and never vertical, but almost always more or less inclined. Be- 
neath each stratum of coal, there is often one of soft clay, or clunch, 
which rarely contains the organic remains of the overlying shale : and 
although the alternating strata of coal be very numerous, it is seldom 
that more than three or four will afford profitable occupation to the 
miner. The'upper seam is commonly broken and impure, and few beds, 
less than two or three feet in thickness, are followed down to any con- 
considerable depth. The depth of the mines will of course greatly 
vary, according to the inclination of the strata, the time they have been 
* See A Sketch of the Natural History of the Cheshire Rock-salt District. By Henry 
Holland, Esq.—Geol. Trans, i. 38. 604 
ARGILLACEOUS IRONSTONE. 
worked, and other circumstances. Our deepest mines are in the coun- 
ties of Durham and Northumberland, and the thickest beds are found 
in Staffordshire. The most productive vary from six to nine feet, 
f 3005. There are several varieties of coal, but, as far as their econo- 
mical applications are concerned, they may principally be reduced to 
two. The coals of Lancashire, Scotland, and most of those raised upon 
the west of England, burn quickly and brilliantly into a light ash : 
while the coal of Northumberland and Durham, becomes soft and puf- 
fy, spouts out bright jets of flame, requires poking to continue in 
combustion, and produces bulky cinders, which, if urged in a violent 
fire or mixed with fresh coals, run into slags and clinkers. 
3006. Though coal is chiefly found in the geological position I have 
mentioned, constituting the independent coal formation of Werner, it is 
likewise found in other situations, amongst newer rocks, and sparingly 
in alluvial soils. But in this country, the main coal formations are 
marked by their position ; their contiguity to limestone and often to 
slate ; by micaceous grits and sandstones ; and, above all, by shale with 
vegetable impressions, decomposing into tenacious blue clay. 
3007. The greater number of geologists are now unanimous as to 
the vegetable origin of coal; and, indeed, its composition, the abun- 
dance of vegetable bodies with which it is often associated, and the gra- 
dual transitions of wood into coal, discoverable in many parts of the 
world, may be considered as satisfactory evidence upon this subject: 
but how it has been formed, is another and more intricate question. 
Dr. Hutton considered coal strata to have been produced by the 
operation of subterranean heat, in the manner already described, act- 
ing upon vegetable bodies and charcoal under exceeding pressure, 
which prevented the usual phenomena of combustion, and hindered 
the escape of the inflammable part. Sometimes, he observes, more 
or less bitumen has been driven off, for we find it in other strata. 
By Mr. Williams, antediluvian timber and peat bog are regarded as 
the source of our present coal; and a variety of curious circumstances, 
which the minute history of coal fields presents, have been adduced as 
favourable to his conclusions. 
3008. The coal miner is often seriously interrupted in his proceed- 
ings, by large fissures or breaks in the strata, and by veins of a hard 
black rock, which cut through the coal, sometimes merely dividing it, 
at others throwing it out of its former position. It is in the neighbour- 
hood of these dykes and troubles, as they are called by the miners, that 
immense quantities of carburetted hydrogen gas are frequently evolv- 
ed, though the coals themselves, and the cavities in the strata, also 
yield it; it constitutes the fire-damp of the mines ; and when it has any 
where collected so as to constitute more than of the volume of 
atmosphere, it becomes explosive whenever a flame is presented to it, 
and the source of such dreadful destruction, that the mind recoils from 
the recital. Formerly the miners, in these dangerous situations, 
availed themselves of the light obtained by the collision of flint and 
steel, which, however, was by no means free from danger, and has been 
completely superseded by Sir Humphry Davy’s safety lamp. 
3009. Another substance which very often attends coal formations, 
is argillaceous iron-stone, both in layers and nodules ; and although a 
poor ore of iron, very seldom yielding more than 30 per cent, of metal, 
it becomes, from its association with coal and limestone (substances re- chalk. 
605 
quired for its reduction), a most important natural product; it is the 
main source of the enormous quantities of iron manufactured in this 
country ; and the history of the various difficulties which have been 
surmounted in completing the processes of its reduction, presents an 
unrivalled picture of skill, ingenuity, and perseverance (725). 
3010. Leaving the districts of red sandstone and red marl, we ob- 
serve a change in the general aspect of the country. There are no 
steep or abrupt precipices : the hills assume a more picturesque and 
luxuriant character, and features of primary country, are 
here softened down into gentle slopes and verdant plains. 
The rocks which now occur are chiefly varieties of limestone and 
sandstone, particularly prolific in organic remains ; among them we 
discern a number of species of which no living semblance is now in 
existence. 
Corals, zoophytes, ammonites, belemnites, nautili, and a variety of 
other fossil remains, are found in the argillaceous limestones, which 
succeed in position to the red sandstone, and which are often called 
white and blue lias limestone. The coast of Dorsetshire, between 
Weymouth and Lyme, presents a very interesting section of these 
strata ; and their continuation through the country is well entitled to 
the notice of the geologist. They decompose into marl, and furnish 
an ingredient in the best water-cements. Sometimes they are of a pe- 
culiar yellow colour, and contain magnesia, when the fossil remains 
are less frequent. 
3011. These strata are succeeded by a species of stone, often called 
Bath-stone, from its abundant occurrence in the vicinity of that city, 
and freestone, or oolite, of which Portland-stone is a notorious variety. 
There then commonly occur various sandstones, with veins of chert 
and oxide of iron ; and, lastly, we arrive at chalk, and superincum- 
bent ALLUVIAL MATTER. 
3012. The examination of the fossil remains in these strata, leads 
to conclusions of much interest and importance. In the strata upon 
the coast of Dorsetshire, below the chalk, we find the remains of an 
animal, which has generally been regarded as a crocodile, or allegator*, 
but there are no fossil relics of mammiferous land animals, either here, 
or in the chalk itself; whence it has been concluded, that oviparous 
quadrupeds are of more ancient date than those of the viviparous class, 
and that dry land and fresh water existed before the formation of 
our present chalk. In the vicinity of Paris the chalk is covered by a 
coarse shell limestone, in which the bones of mammiferous sea animals 
have been found by Cuvier ; but no bones of mammiferous land quad- 
rupeds occur, till we reach the more recent and superincumbent strata. 
3013. The chalk presents the geologist with much matter of spe- 
culation. In England it is a very abundant formation, and the round- 
backed hills covered with verdure which mark the eastern counties, 
are very characteristic of it. Salisbury Plain and Marlborough Dowms 
form a centre, whence the chalk emanates, in a north-eastern direction, 
through the counties of Buckingham, Bedford, and Cambridge, and 
terminates on the Norfolk coast. In an easterly direction it traverses 
* Sir Everard Home, in examining the fossil bones of this animal, has thrown considera- 
ble doubt upon the above conclusion; and, from a peculiarity in the structure of its spine, 
resembling- that of the proteus, has called it proteorrhachius. 606 
TRAP-ROCKS. 
Hampshire, Surry, and Kent, and terminates at Dover; and another 
arm passing through Sussex, east south-east, forms the South Downs, 
and the lofty promontory of Beachy Head. Parallel ridges of sand- 
stone generally accompany the chalk, and in Wiltshire, Berkshire, and 
some other counties, large blocks of granular siliceous sandstone lie 
scattered upon its surface; of these the celebrated druidical relics, 
called Stonehenge, appear to have been constructed, with the exception 
of one of the blocks, which is of greenstone. The lower beds of 
chalk are generally argillaceous, or contain no flints, and 
few organic remains. The upper beds abound in fossil relics, of the 
kinds before alluded to, and in flints sometimes regularly arranged in 
distinct nodules, at other times remarkably intersecting the chalk in 
thin seams. The formation of flint has been much speculated upon, 
but no plausible theory has yet been adduced in regard to it. 
3014. In the south of England the chalk is covered with gravel and 
clay, the history of which is extremely curious, on account of the fos- 
sils which they contain, and the evidence they afford of repeated inun- 
dations of salt and fresh water upon the same spot. There are two 
celebrated concavities filled with such materials which have been call- 
ed the London and the Isle of Wight Basins. The former is bounded 
by the chalk-hills proceeding from Wiltshire to the south of the Kent- 
ish coast, in one direction, and to the northern point of the Norfolk 
coast in another ; and it is open to the ocean upon the Essex, Suffolk, 
and Norfolk coasts, which show sections of its contents. 
The numerous wells which have been dug in the neighbourhood of 
London, and the canals, tunnels, and other excavations and public 
works which have been carried on, have lately made us acquainted 
with many curious facts respecting the contents of this basin. 
It deserves remark, that all the bones of viviparous land quadru- 
peds have either been found in the uppermost fresh water deposits, or 
in those alluvial formations of the ocean, which appear to have been 
the result of violent transportations of materials, rather than of quiet 
depositions ; so that it is probable these animals began to exist during 
that state of the world which preceded the last inundation of the sea. 
The palceotheria, anaplotheria, and other unknown genera describ- 
ed by Cuvier, are found in the lowest parts of the upper fresh-water 
formation, placed immediately under the upper marine formation. 
Some oviparous quadrupeds and fresh-water fish are found along with 
them, and they are covered by alluvial deposits, containing marine 
relics. 
The unknown or extinct species belonging to known genera, such as 
the mastodon, elephant, hippopotamus and rhinoceros, are never asso- 
ciated with the more ancient or extinct genera, but are discovered 
usually in the sea-water deposits ; and the bones of species resembling 
those that now exist, ase found upon the sides of rivers, or in the bot- 
toms of ancient lakes and marshes, or in peat-bogs, or in caverns and 
fissures of rocks ; and, in consequence of their superficial situation, 
they are generally much injured. 
3015. Of a very singular and important series of rocks, I have yet 
made no mention. They occur indiscriminately in primary and se- 
condary countries, and are not less varied in their characters and as- 
pects, than in their situation. These are the trap-rocks of the Wer- 
nerians, and the whinstones of Dr. Hutton. They include the rocks 
called greenstone, basalt, amvgdaloid, and toadstone, and are dis- 607 
tinguished into primary, transition, and floetz traps, by the school of 
Frey burgh. 
By the term greenstone, we mean a compound of hornblende and 
feldspar, differing extremely in its appearance, being sometimes so fine 
grained as to appear homogeneous ; at other times presenting distinct, 
and often large, crystals of hornblende. Basalt is always a homogene- 
ous rock, and abounds in black oxide of iron. Its cavities are often 
filled with calcareous spar, zeolite, and agate nodules. 
Greenstone is met with in many parts of England immediately upon 
granite and primary rocks; and it assumes the character of its neigh- 
bours, breaking into large blocks and masses of very irregular appear- 
ance. In this state it is seen in Cornwall, at the Lizard-Point. Upon 
the north side of the Welsh mountains, a chain of greenstone follows 
the slate, which, in some places, is columnar, as upon Cader Idris, and 
it forms a singular concavity near the summit of that mountain, very 
like the crater of a volcano. In Derbyshire these rocks are among 
the transition series of Werner. They form strata, and fill cavities in 
the limestone. In coal-fields they constitute dykes, or veins ; and, 
among the newest and secondary strata, they are seen in sandstone at 
Edinburgh, and upon the coast of Antrim they are incumbent upon, 
and alternate with, chalk. The annexed wood-cut, taken from a sketch 
ORIGIN' OF BASALT. 
by Dr. Mac Culloch, engraved in the Geological Transactions, Vol. iii., 
represents a remarkable dislocation occurring at Gow’s Bridge, in 
Glentilt, in Scotland, of the schistose strata by the black mass of horn- 
blende rock, which also contains an embedded mass of marble. 
3016. The common observer, to whom a piece of basalt is presented, 
would presently announce it to be the produce of a volcano, and the 
analogy between it and lava is most striking. This alone would justify 
us in concluding, that whinstone is the produce of fire. But the Hut- 
tonian hypothesis, as applied to its origin, becomes much more satisfac- 
tory, when we contemplate the effects produced upon the strata into 
which it has been thrown, or upon the substances in its vicinity. Thus 608 
ASPECT OF BASALT. 
the sandstone of Salisbury Craigs, near Edinburgh, is broken, indurated, 
and even apparently fused by its irruption. The soft white limestone 
of the county of Antrim, where in contact with the basaltic dyke, is 
hardened and rendered crystalline, like marble and calcareous spar ; 
and the coal in the same county is coaked, as it were, where touched 
by the whinstone. At the same time, the dykes themselves bear evi- 
dent marks of igneous fusion. They are more regularly crystallized 
in the centre than upon the surface, an effect wrhich may be J1 re- 
ferred to the different rates of cooling, in the melted mass, and 
which may even be imitated artificially with the slag of an iron fur- 
nace. 
Perhaps the most remarkable phenomenon concerning basalt, is its 
occasional columnar structure, an appearance which lava sometimes 
assumes. Upon this subject Sir James Hall’s experiments are of ex- 
treme interest; and, when conjoined with those of Mr. Watt, produce 
a further, and, indeed, almost irresistible evidence in favour of the ig- 
neous origin of basalt. 
3017 In accounting for the humid origin of basalt, the Neptunists 
refer to the columnar cracking of clay, mud, starch, &rc., during dry- 
ing ; and in this they fancy an analogy to basaltic columns ; but in these 
cases, there are always chasms and vacuities produced by the shrinking 
of the mass ; whereas the columns of basalt are so closely connected, 
that the thin blade of a knife can scarcely be thrust between them. 
Upon the whole, the Huttonian theory may be considered as no where 
more free from objections, than where it applies to basalt; while the 
hardening, contortions, and breaking of the strata by whin dykes, and 
the numerous analogies of basalt and lava, are to the Neptunians para- 
doxes which admit of no solution. 
3018. Of columnar basalt, the British dominions present the noblest 
specimens in the known wrorld. Upon the coast of Antrim, in Ireland, 
massive and columnar basalt is seen in all its varieties, the former 
abounding in deep and lofty caverns, the latter presenting various fa- STAFFA. 
§ades to the ocean. The Giant’s Causeway, a small part of which, 
with the neighbouring coast, is shown in the above wood-cut, consists 
of three piers of columns, which extend some hundred feet into the 
sea. It is surrounded by precipitous rocks, from two hundred to four 
hundred feet high, in which there are several striking assemblages of 
columns, some vertical, some bent or inclined, and some horizontal, 
and, as it were, driven into the rock. Bengore, which bounds the 
Causeway on the east, consists of alternate ranges of tabular and mas- 
sive, with columnar basalt. But amongst the various and grand objects 
on this coast, Pleskin is perhaps the most striking ; it presents several 
colonnades of great height and regularity, separated from each other by 
tabular basalt; and at Fairhead there is a range of columns of from 10 
to 20 feet in diameter, and between 200 and 300 feet high, supported 
upon a steep declivity, and forming a terrace which towers nearly 600 
feet above the waves beneath. He who would really see the sublime 
should visit this stupendous promontory. 
Another basaltic district, which I am inclined to regard as exceeding 
the former in magnificent peculiarities, is that which presents itself in 
sailing down Loch-Nagaul, in Mull, towards the Isle of Tiree. The 
coast of Mull, upon the right and left, exhibits the step-like appearance 
of basaltic rocks in great perfection, and has fine caverns and columns ; 
the islands of Ulva and Gometra rise with the abrupt and irregular pre- 
cipices common to this formation. The Treshamish Isles exhibit co- 
lumnar and massive basalt, and in the midst of this curious panorama, 
Staffa presents itself. The columns, which are from 30 to 50 feet high*, 
are approached by a fine causeway, rising gradually from the deep, and 
they appear to support an immense weight of tabular basalt. The pil- 
lars are perpendicular, inclined, and in places extremely curved ; and 
in the Cave of Fingal the ranges of columns extend in long perspective 
into the interior of the rock, presenting a scene of such unrivalled 
grandeur, as hitherto to have foiled all attempts of the poet to describe, 
or of the painter to represent. The wood-cut at the head of the next 
Section, copied from Dr. Mac Culloch’s sketch, represents the Cause- 
way and entrance of the Cave. 
* See Dr. Mac Cviloch’s Description of the Western Islands of Scotland, Vol. ii, p. !• METALLIC VEINS-. 
Section IV. Of Metallic Veins.—Of the General Causes of the De- 
composition of Rocks.—Of Volcanoes: and of the Analysis of Soils. 
3019. Besides the veins of lapideous substances, the fissures filled 
with debris and rubbish, the dykes, the beds of salt, and the fields of 
coal, there are diffused through the strata a variety of other treasures, 
among which the metals are of the utmost interest and importance. 
By the term Mineral Vein, we mean a separation in the continuity of a 
rock of determinate width, but extending indefinitely in length and 
depth, filled with metallic ores, and crystalline substances, differing 
from the rock itself. 
Nearly all rocks are occasionally thus traversed, but the middle se- 
ries those in which metals are most abundant. In Cornwall, for 
instance, tin occurs both in the granite and slate ; but it is most abun- 
dant in the latter, and the vein occasionally runs between the two rocks, 
so that one wall consists of granite, and the other of slate. The 
metal is often separated from the rock by thin layers of clay, or of 
stony materials, called Deads, which also intermix with the ore, and 
form its gangue or matrix. 
3020. The richest metallic veins run, without exception, east and 
west. Those which run north and south being usually filled w ith sto- 
ny materials. The latter veins appear of posterior date to the former, 
for they often intersect them throwing them out of their regular course ; 
generally a few inches only east and west, but many fathoms north and 
south. These cross courses often interfere with the treasures of the 
metallic vein, though, when solid, they are sometimes of great service 
in keeping out water. 
3021. The extent to which veins may be pursued, is extremely va- 
rious, and depends much upon accidental circumstances. Sometimes a 
cross course cuts the vein, and puts an end to the miner’s hopes, he 
being unable to discover its continuation after such interruption ; some- 
times the depth of the vein becomes so great, that it cannot be prudent- 
ly pursued j sometimes a rich lode of metal suddenly disappears, or CONTENTS OF METALLIC VEINS. 
611 
vanishes into thin strings, which, though often quite lost, occasionally 
reunite into a good vein, or bunch of metal. So that, taking all these 
circumstances into account, between two or three miles is usually the 
utmost extent to which a vein has been pursued*, 
3022. Veins vary in width, from an inch or two, to 30 or 40 feet, 
but the middle-sized veins are usually most prolific, the larger becom- 
ing relatively poor. The influx of water was formerly an insuperable 
impediment to the pursuit of a vein, and remains now a serious and 
expensive obstacle to mining. Formerly many veins in Cornwall were 
only worked for tin, which, at greater depths, have lately yielded abun- 
dance of copper ; but in Cornwall copper is never found without water, 
and all the mines of that metal require drainage by engines, or other 
means. 
3023. Concerning the original formation of metallic veins, there has 
been considerable collision of sentiment among geologists ; but two 
circumstances seem sufficiently obvious ; one, that they are of later 
date than the containing strata, that they are not contemporaneous; 
and the other, that their contents have been in a fluid state. The 
former position is indicated by their intersecting different strata ; the 
latter, by the crystalline forms of the substances they contain. The 
Neptunians tell us that veins have been filled by metallic and lapideous 
solutions flowing in from above, but they do not inform us of the na- 
ture of the solvent which held the different bodies they present; nor 
can we guess why its contents are deposited exclusively in the vein, 
and not found upon the adjacent surface. 
3024. The Plutonists consider veins as filled from below, by the 
injection of matters in igneous fusion ; and in the shifting, breaking, and 
dislodgement of the strata, they read the force with which these ope- 
rations have been performed. The validity of hypotheses is only to 
be estimated by their accordance with facts ; and although there be 
many inexplicable phenomena attending metallic veins, yet the nature 
of their contents is such as to favour the igneous hypothesis, and to lead 
to the belief that fire, not water, has been the grand solvent of 
which nature has here availed herself. That the metals have passed 
from the fluid to the solid state, seems sufficiently obvious, from their 
crystalline form; and it is much more probable that they should have 
been liquefied by heat than by any other solvent. 
Sulphur is very commonly found united to metallic bodies, and the 
greater number of metallic ores contain that element. Such com- 
pounds are easily produced by the artificial agency of fire, but with 
great difficulty by any other process. 
3025. A very curious fact in the history of veins is, that they are of 
different dates, for one vein often intersects another, and we are thus 
enabled to judge of their relative ages. In the county of Cornwall, 
one of the richest mining districts of the world, we observe some re- 
markable circumstances of this kind. Where a copper and a tin vein, 
for instance meet, the former always cuts through the latter, and ge- 
nerally throws it out of its old course, greatly to the distress of the 
miner, who sometimes cannot find its continuation, or at least is put to 
* See a valuable paper on the Veins of Cornwall, by Mr. W. Phillips. Geol. Trans- 
Vol. ii., and also annexed to his Selection of Facts. 612 
DECOMPOSITION OF ROCKS. 
much difficulty and expense to do so. It appears, therefore, that tin 
veins are invariably older than those of copper. Sometimes, as in 
Derbyshire, the metallic ores lie in large longitudinal cavities, called 
pipe veins. 
3026. In searching for veins of the useful metals, there are certain 
indications of which the experienced miner sometimes profitably avails 
himself. Thus, a green earthy matter is a good symptom in a tin mine ; 
a brown ochrey earth, and compact iron pyrites, are regarded as fa- 
vourable omens in a copper mine. 
Detached pebbles of ore, or fragments of vein-stones, have some- 
times led to the riches of the vein, and tin has especially been thus 
discovered in Cornwall. 
In older mineralogical works we read much upon these and other 
subjects. Flames of light have been described as playing over a dis- 
trict which afterwards has been found to contain subterranean riches, 
and this may have arisen from the good electrical conducting powers of 
the vein. The waters issuing from the soil sometimes hold metallic 
salts in solution, and repositories of the metals have been discovered 
by circumstances of this kind. Copper veins tinge waters blue, and 
a piece of grease put into them becomes rapidly stained of that co- 
lour. 
There is no popular notion more common than that metals grow in 
the veins : an idea which may very probably have originated from ob- 
serving the depositions of one metal by the introduction of another 
into its solution, as when silver is precipitated by the introduction of a 
plate of copper into its solution, or copper by iron. 
3027. Districts rich in the metals are generally barren, and seem 
peculiarly dreary and desolate to the traveller. This partly arises 
from the nature of the strata ; partly from the heaps of rubbish and 
hills of stone thrown upon the surface : and partly from the operations 
carrying on in the vicinity, being inimical to vegetation. The high 
road through Cornwall, especially.near Redruth, is an excellent spe- 
cimen of this kind of country; while, at the same time, the romantic 
beauty and luxuriant vegetation of many parts of that county, and of 
Devonshire, prove that exterior cultivation is net always incompatible 
with internal riches. The neighbourhood of the Parys Mountain, in 
Anglesea, is singularly marked by sterility and gloominess. The soil, 
naturally unproductive, is rendered more so by the poisonous waters 
that traverse it, and the sulphurous vapours that float around. There 
are not only no shrubs and trees, but the barrenness is unrelieved even 
by a single blade of grass, or the rusty green of a hardy lichen. 
3028. I have hinted above at the relative permanence and durability 
of the different kinds of rocks, and it has been found that the unstrati- 
fied, or primary, substances, are least acted upon by the elements ; 
that these have retained their great and pristine elevation, while the 
secondary strata have been washed from their sides and summits, whose 
fugged and abrupt outline records this devastation. Every one who 
views the mountain side strewed with immense blocks of materials 
transported from distant summits, and discovers the dells and valleys 
filled with fragments and pebbles of the neighbouring rocks, will allow 
that a constant system of disintegration and decay is here carrying on ; 
but the geologist, not content with the mere observance of the fact, 
will endeavour to trace it to its source, and follow it up to its ultimate 
effect. r CAUSES OP THE DECAY OF ROCKS. 
3029. The change of temperature to which the earth’s surface is 
constantly submitted, is one great cause of the slow destruction of its 
most solid and durable constituents ; and when to this is added the gi- 
gantic power with which water, in becoming ice, opposes the obstacles 
to its expansion, we have an agent nearly resistless. The fissures that 
occur between the blocks and masses of the granites, porphyries, and 
similar rocks, become filled with water, which, in the act of freezing, 
expands so as slowly to remove them from each other ; their edges 
and angles become thus open to the attacks of the weather, and by a 
slow dislodgement they fall into the valleys or rivers, or are at once 
cast into the ocean. Where the materials are of a more yielding and 
frangible texture, this destruction is proportionally rapid, and the in- 
fluence of the weather upon slate mountains, is often such as to pro- 
duce hills of fragments at their feet : the softer substance of the 
secondary and horizontal strata is, of course, yet more easily and 
quickly degraded. 
3030. Masses of rock, thus loosened from their original beds, be- 
come new and powerful instruments of destruction ; they roll down 
the precipices, wearing themselves and the surface that bears them, 
and, if near the sea, or carried thither by rivers, they become “ a 
part of the mighty artillery with which the ocean assails the bulwarks 
of the land they are impelled against the coasts, from which they 
break off other fragments : and the whole thus ground against each, 
other, whatever be their hardness, are reduced to gravel ; the smooth 
surface and rounded masses of which are convincing proofs of the 
manner in which it was formed. 
3031. It is by operations of this kind, not performed in a day, but in 
ages, that nature has indented and carved out the earth’s surface ; 
that the rivers seem to have cut their own beds ; that the land is under- 
going gradual demolition ; and that the materials wdfich we have else- 
where considered as consolidated at, and elevated from, the bottom of 
the ocean, are gradually restoring to the parent deep. These are me- 
chanical agents, but they are not unassisted by the chemical energies of 
matter; and, in this respect, the solvent powers of water may be con- 
templated as effecting most important changes.—Kidd’s Essay, p. 181. 
3032. By impregnation with carbonic acid, water acquires a great 
solvent power over carbonate of lime (642,) and in trickling through, 
such strata becomes saturated with it, and, on exposure, again deposits 
it, in consequence of the escape of the gaseous solvent; it is thus that 
the stalactitical concretions of limestone caverns are produced, as in 
the Fluor Mine, and Peak Cavern of Derbyshire ; and, in many cases, 
the once empty chasms are entirely choaked up by this sparry de- 
posit. The power of incrustation, thus possessed by some waters, is 
such as rapidly to cover extraneous bodies thrown into them with a 
calcareous coating, of which the petrifying spring of Matlock furnishes 
a good example. 
3033. The sands upon flat coasts are sometimes agglutinated by this 
action of water, so as to produce a new rock ; or, as the Wernerians 
would call it, a new formation. This has probably been the case with 
the stone in which the galibi, or human skeletons of Guadaloupe, are 
found (Phil. Trans. 1816,) and the process is constantly going on upon 
the coast of Cornwell, in the parish of St. Columb, where the water, 
having percolated the neighbouring rocks, becomes slightly carbonated 614 
TILLING UP OP LAKES, 
and ferruginous, and thus serving as a cement to the sand, produces a 
hard stone, which is used as a building material, and for making cattle- 
troughs. In the walls of some of the oldest churches in Cornwall, as 
in St. Burian, Gwithian, Crantock, Cubert, 4*c., are large masses of 
this sandstone, which has thus long resisted decomposition. When 
water is hot, and slightly alcaline, it dissolves siliceous earth, as shown 
by the deposits of the Geysers, or Boiling Fountains of Iceland. 
3034. Some rocks suffer, in consequence of the action of air and 
water upon the black oxide of iron which they contain, and which, in 
passing into the state of brown oxide, occasions a crumbling of the 
mass. Much of the soil upon the coast of the county of Antrim, in 
Ireland, is thus derived from the decomposition of basalt, which, how- 
ever, in other cases, singularly resists change, as in Staffa, where the 
columns, though exposed to the violence of the ocean, retain a sharp 
angularity and black colour. These differences depend upon the de- 
gree of induration of the basalt. 
3035. Rocks containing alcali seem often to decompose rapidly, in 
consequence of the loss of that ingredient. The quick disintegration 
of much of the Cornish granite is well known, and it furnishes a valu- 
able material for the manufacture of pottery. The feldspar of this 
granite contains a considerable portion of potassa, but the white earth 
into which it is resolved yields no traces of it. 
3036. The chemical agencies of different bodies presented to each 
other in the strata, are also often connected with the production of en- 
tire new substances. Thus the decomposition of pyrites in chalk pro- 
duces sulphate of lime ; in aluminous slate it gives rise to the produc- 
tion of alum; and in the cliffs at Newhaven, on the Sussex coast, a 
very curious series of changes is going on. A stratum of marl, con- 
taining decomposing pyrites, lies upon the chalk, which gives rise to 
the formation of sulphate of alumina ; this is decomposed by the chalk ; 
and aluminous earth, selenite, and oxide of iron, are the results. 
3037. Thus, by mechanical operations and chemical changes, some- 
times separate and sometimes united, the rugged peaks and abrupt 
precipices are gradually wearing and softening down, and giving rise 
to rounded summits, gentle slopes, and habitable surfaces. The de- 
tritus so produced is carried by rills, and brooks, and rivers towards 
the low lands, where it is deposited ; or it is transported towards the 
sea, where it forms bars and islands at the mouths of rivers ; or it is 
employed in levelling uneven surfaces, and filling cavities and basins, 
as where the rivers are broken in their course by the intervention of 
lakes, all of which are filling up, as may be learned even by hasty in- 
spection. This is no where more conspicuous than in the waters which 
adorn the scenery of Westmoreland and Cumberland, especially Der- 
went Water, at the Borrowdale extremity of which the meadow is an- 
nually increasing, and adding to the circumjacent field ; and the ex- 
amination of the bank between Derwent and Bassenthwaite, shows 
that the two lakes were once united, and that the present separa- 
tion is alluvial matter, or a bar thrown up by the concurrent streams 
of Newland’s Water, on the west, and the Greta on the east. The 
filling up of lakes, until they ultimately become merely a part of the 
river that now traverses, but once fed them, is too obvious to require 
further illustration ; it is the reason why the stream, which has its exit 
from a lake, is generally clear, while the torrents which supply it are 
loaded with matters in minute mechanical division. CAUSE OF VOLCANIC ERUPTIONS. 
3038. While the destructive agencies of the elements are thus call- 
ed into action for the production and increase of habitable surface, we 
observe other causes tending to the same effect, and none more won 
derful than the incessant labours of those insect tribes which collect 
and accumulate solid matter from the ocean, and form the rocks of 
coral common in the seas of warm climates.—Kidd’s Essay, p. 219. 
3039. But the most striking sources of decay and reproduction, are 
those dependent upon volcanic phenomena. 
The form of volcanic hills is usually conical, of which the outline of 
the Bay of Naples presents a fine panorama. One of its hills serves 
to give some idea of the vast powers of the subterranean agents ; it is 
about 1000 feet high, and three miles in circumference, and was raised, 
in 1238, in a single night*. 
3040. In June 1811, a volcano was disfcovered in the sea off St. 
Michael, and it formed an island about a mile in circumference.—Phil. 
Trans., 1812. 
3041. To describe the phenomena of volcanic eruptions with all 
attending circumstances, would be foreign to our present purpose ; but 
as the same causes may have been active in producing other geological 
phenomena, it becomes right to mention the subject. 
Until lately, the cause of volcanic fire was referred to sulphur, coal, 
and other common inflammable matters, which were supposed to be 
burning in immense masses within the earth, and thus to give rise to 
the tremendous explosions and ejections of lava and stones attending 
the eruption ; but the products ill accord with such an explanation. 
Earthy, alcaline, metallic, and stony bodies united, form the lava ; and 
steam and hydrogen gas accompany its throwing forth ; and as the pro- 
ducts of combustion always have a reference to the combustible, such 
matters were not likely to be produced from sulphur or coal. 
The discoveries of Sir H. Davy have enlightened this, as well as 
every other branch of chemistry, and from them we may deduce a 
very adequate solution of the problem of volcanoes, for we have only 
to suppose the access of water to large masses of those peculiar metals 
which constitute the alcaline and earthy b§ses, and we are possessed of 
all that is wanted to produce the tremendous effects of earthquakes and 
volcanoes ; for what power can resist the expansive force of steam, 
and the sudden evolution of gaseous fluids, accompanied by torrents of 
the earths in igneous fusion, which such a concurrence of circumstan- 
ces would give rise to, and which are the actual concomitants of vol- 
canic eruptions ? 
From the same source the Huttonian theory derives great addition- 
al plausibility, for its feeble parts were those which related to the re- 
quired expansive forces, to the intense continuance of heat, to its occa- 
sional increase and decrease, and to the existence of a species of fuel 
adequate to the various effects that have been described. The metals 
of the earths are equal to the production of all these complicated and 
apparently incompatible effects, and these and water are the sole agents 
required. 
3042. The principal circumstances that tend to the formation of 
soils, and to modify their composition, have been adverted to in this 
* See Sir Wra. Hamilton’s Paper in }Jie Phil. Trans. for 1771, 616 
PHYSICAL PROPERTIES OF SOILS. 
Chapter; and, from the properties of their component parts, else- 
where detailed, the means of analyzing them are to be deduced ; but 
as this is a subject upon which the agriculturist may sometimes find it 
expedient to employ himself, I insert the following popular instructions 
upon it, from Sir H. Davy’s Elements of Agricultural Chemistry: 
“ In cases when the general nature of the soil of a field is to be as- 
certained, specimens of it should be taken from different places, two or 
three inches below the surface, and examined as to the similarity of 
their properties. It sometimes happens, that upon plains the whole of 
the upper stratum of the land is of the same kind, and, in this case, 
one analysis will be sufficient; but in valleys, and near the beds of 
rivers, there are very great differences ; and it now and then occurs 
that one part of a field is calcareous, and another part siliceous ; and 
in this case, and in analogous cases, the portions different from each 
other should be separately submitted to experiment. 
“ Soils, when collected, if they cannot be immediately examined, 
should be preserved in phials quite filled with them, and closed with 
ground-glass stoppers. 
“ The quantity of soil most convenient for a perfect analysis, is 
from 200 to 400 grains. It should be collected in dry weather, and 
exposed to the atmosphere till it becomes dry to the touch. 
“The specific gravity of a soil, or the relation of its weight to that 
of water, may be ascertained by introducing into a phial which will con- 
tain a known quantity of water, equal volumes of water and of soil, 
and this may be easily done by pouring in water till it is half full, and 
then adding the soil till the fluid rises to the mouth; the difference be- 
tween the weight of the soil and that of the water will give the result. 
Thus, if the bottle contains 400 grains of water, and gains 200 grains 
when half filled with water and half with soil, the specific gravity of 
the soil will be 2, that is, it will be twice as heavy as water ; and if it 
gained 165 grains, its specific gravity would be 1.825, water being 
1.000. 
“ It is of importance that the specific gravity of a soil should be known, 
as it affords an indication quantity of animal and vegetable mat- 
ter it contains ; these substances being always most abundant in the light- 
er soils. 
“ The other physical properties of soils should likewise be examin- 
ed before the analysis is made, as they denote, to a certain extent, their 
composition, and serve as guides in directing the experiments. Thus, 
siliceous soils are generally rough to the touch, and scratch glass when 
rubbed upon it: ferruginous soils are of a red or yellow colour ; and 
calcareous soils are soft. 
“ 1. Soils, though as dry as they can be made by continued expo- 
sure to air, in all cases still contain a considerable quantity of water, 
which adheres with great obstinacy to the earths and animal and vege- 
table matter, and can only be driven off from them by a considerable 
degree of heat. The first process of analysis is, to free the given 
weight of soil from as much of this water as possible, without, in other 
respects, affecting its composition ; and this may be done by heating it 
for ten or twelve minutes over an Argand’s lamp, in a basin of porce- 
lain, to a temperature equal to 300 Fahrenheit; and if a thermometer 
is not used, the proper degree may be easily ascertained by keeping 
a piece of wood in contact with the bottom of the dish ; as long as the 
colour of the wood remains unalter%I, the heat is not too high: but when the wood begins to be charred, the process must be stopped. A 
small quantity of water will perhaps remain in the soil even after this 
operation, but it always affords useful comparative results ; and if a 
higher temperature were employed, the vegetable or animal matter 
would undergo decomposition, and, in consequence, the experiment be 
wholly unsatisfactor}'. 
“ The loss of weight in the process should be carefully noted, and 
when in 400 grains of soil it reaches as high as 50, the soil may be 
considered as in the greatest degree absorbent, and retentive of water, 
and wall generally be found to contain much vegetable or animal matter, 
or a large proportion of aluminous earth. When the loss is only from 
20 to 10, the land may be considered as only slightly absorbent and 
retentive, and siliceous earth probably forms the greatest part of it. 
“ 2. None of the loose stones, gravel, or large vegetable fibres should 
be divided from the pure soil till after the water is drawn off: for these 
bodies are themselves often highly absorbent and retentive, and, iu 
consequence, influence the fertility of the land. The next process, 
however, after that of heating, should be their separation, which may 
be easily accomplished by the sieve, after the soil has been gently bruis- 
ed in a mortar. The weights of the vegetable fibres, or wood, and 
of the gravel and stones, should be separately noted down, and the na- 
ture of the last ascertained ; if calcareous, they will effervesce with 
acids ; if siliceous, they will be sufficiently hard to scratch glass ; and 
if of the common aluminous class of stones, they will be soft, easily 
cut with a knife, and incapable of effervescing with acids. 
“ 3. The greater number of soils, besides gravel and stones, con- 
tain larger or smaller proportions of sand, of different degrees of fine- 
ness : and it is a necessary operation, the next in the process of ana- 
lysis, to detach them from the parts in a state of more minute division, 
such as clay, loam, marl, vegetable and animal matter, and the matter 
solute in water. This may be effected in a way sufficiently accurate, 
by boiling the soil in three or four times its weight of water ; and 
when the texture of the soil is broken down, and the water cool, by 
agitating the parts together, and then suffering them to rest. In this 
case, the coarse sand will generally separate in a minute, and the finer 
in two or three minutes, whilst the highly-divided earthy, animal, or 
vegetable matter will remain in a state of mechanical suspension for a 
much longer time ; so that, by pouring the water from the bottom of 
the vessel, after one, two, or three minutes, the sand will be principal- 
ly separated from the other substances, which, with the water contain- 
ing them, must be poured into a filter, and, after the water has passed 
through, collected, dried, and weighed. The sand must likewise be 
weighed, and the respective quantities noted down. The water of lixi- 
viation must be preserved, as it will be found to contain the saline and 
soluble animal or vegetable matters, if any exist in the soil. 
“4. By the process of washing and filtration, the soil is separated 
into two portions, the most important of which is generally the finely- 
divided matter. A minute analysis of the sand is seldom or never ne- 
cessary, and its nature may be detected in the same manner as that of 
the stones or gravel. It is always either siliceous sand, or calcareous 
sand, or a mixture of both. If it consist wholly of carbonate of lime, 
it will be rapidly soluble in muriatic acid, with effervescence ; but if it 
consist partly of this substance, and partly of siliceous matter, the res- 
ANALYSIS OF SOILS. ANALYSIS OF SOILS. 
pective quantities may be ascertained by weighing the residuum after 
the action of the acid, which must be applied till the mixture has ac- 
quired a sour taste, and has ceased to effervesce. This residuum is 
the siliceous part; it must be washed, dried, and heated strongly in a 
crucible ; the difference between the weight of it, and the weight of 
the whole, indicates the proportion of calcareous sand. 
“ 5. The finely-divided matter of the soil is usually very compound 
in its nature ; it sometimes contains all the four primitive earths of 
soils, as well as animal and vegetable matter ; and to ascertain the pro- 
portion of these with tolerable accuracy, is the most difficult part of 
the subject. 
“ The first process to be performed, in this part of the analysis, is 
the exposure of the fine matter of the soil to the action of muriatic 
acid. This substance should be poured upon the earthy matter in an 
evaporating basin, in a quantity equal to twice the weight of the earthy 
matter; but diluted with double its volume of water. The mixture 
should be often stirred, and suffered to remain for an hour, or an hour 
and a half, before it is examined. 
“ If any carbonate of lime or of magnesia exist in the soil, they will 
have been dissolved in this time by the acid, which sometimes takes 
up likewise a little oxide of iron; but very seldom any alumina. 
“ The fluid should be passed through a filter ; the solid matter col- 
lected, washed with rain-water, dried at a moderate heat, and weighed. 
Its loss will denote the quantity of solid matter taken up. The wash- 
ings must be added to the solution, which, if not sour to the taste, must 
be made so by the addition of fresh acid, when a little solution of 
prussiate of potassa and iron must be mixed w’ith the whole. If a blue 
precipitate occurs, it denotes the presence of oxide of iron, and the 
solution of the prussiate must be dropped in till no farther effect is 
produced. To ascertain its quantity, it must be collected in the same 
manner as other solid precipitates, and heated red ; the result is qxide 
of iron, which may be mixed with a little oxide of manganese. 
“ Into the fluid freed from oxide of iron, a solution of neutralized 
carbonate of potash must be poured till all effervescence ceases in it, 
and till its taste and smell indicate a considerable excess of alcaline 
salt. 
“ The precipitate that falls down is carbonate of lime, it must be 
collected on the filter, and dried at a heat below that of redness. 
“ The remaining fluid must be boiled for a quarter of an hour, when 
the magnesia, if any exist, will be precipitated from it, combined with 
carbonic acid, and its quantity is to be ascertained in the same manner 
as that of the carbonate of lime. 
“ If any minute proportion of alumina should, from peculiar cir- 
cumstances, be dissolved by the acid, it will be found in the precipitate 
with the carbonate of lime, and it may be separated from it by boiling 
it for a few minutes with soap lye, sufficient to cover the solid matter ; 
this substance dissolves alumina, without acting upon carbonate of lime. 
“ Should the finety-divided soil be sufficiently calcareous to effer- 
vesce very strongly with acids, a very simple method may be adopted 
for ascertaining the quantity of carbonate of lime, and one sufficiently 
accurate in all common cases. 
“ Carbonate of lime, in all its states, contains a determinate propor- 
tion of carbonic acid, i. e., nearly 43per cent., so that when the quan- tity of this elastic fluid, given out by any soil during the solution of its 
calcareous matter in an acid is known, either in weight or measure, the 
quantity of carbonate of lime may be easily discovered. 
“ When the process by diminution of weight is employed, two parts 
of the acid and one part of the matter of the soil must be weighed in 
two separate bottles, and very slowly mixed together till the efferves- 
cence ceases; the difference between their weight before and after 
the experiment, denotes the quantity of carbonic acid lost; for every 
four grains and a quarter of which, 10 grains of carbonate of lime 
must be estimated. 
“ 6. After the calcareous parts of the soil have been acted upon by 
muriatic acid, the next process is to ascertain the quantity of finely- 
divided insoluble animal and vegetable matter that it contains. 
“ This may be done with sufficient precision, by strongly igniting it 
in a crucible over a common fire till no blackness remains in the mass. 
It should be often stirred with a metallic rod, so as to expose new sur- 
faces continually to the air ; the loss of weight that it undergoes de- 
notes the quantity of the substance that it contains destructible by fire 
and air. 
“ It is not possible, without very refined and difficult experiments, 
to ascertain whether this substance is wholly animal or vegetable mat- 
ter, or a mixture of both. When the smell emitted during the inci- 
neration is similar to that of burnt feathers, it is a certain indication of 
some substance either animal or analogous to animal matter ; and a co- 
pious blue flame at the time of ignition, almost always denotes a consi- 
derable proportion of vegetable matter. In cases when it is necessary 
that the experiment should be very quickly performed, the destruction 
of the decomposable substances may be assisted by the agency of ni- 
trate of ammonia, which at the time of ignition may be thrown gradu- 
ally upon the heated mass in the quantity of 20 grains for every hun- 
dred of residual soil. It accelerates the dissipation of the animal and 
vegetable matter, which it causes to be converted into elastic fluids ; 
and it is itself at the same time decomposed and lost. 
“ 7. The substances remaining after the destruction of the vegeta- 
ble and animal matter, are generally minute particles of earthy matter, 
containing usually alumina and silica, with combined oxide of iron or 
of manganese. 
“To separate these from each other, the solid matter should be 
boiled for two or three hours with sulphuric acid, diluted with four 
times its weight of water ; the quantity of the acid should be regulat- 
ed by the quantity of solid residuum to be acted on, allowing for every 
hundred grains two drachms, or 120 grains, of acid : 
“ The substance remaining after the action of the acid, may be con- 
sidered as siliceous : and it must be separated and its weight ascertain- 
ed, after washing and drying in the usual manner. 
“ The alumina, and the oxide of iron and manganesum, if any exist, 
are all dissolved by the sulphuric acid ; they may be separated by- 
succinate of ammonia, added to excess, which throws down the oxide 
of iron ; and by soap lye, which will dissolve the alumina, but not the 
oxide of manganese : the weights of the oxides ascertained after they 
have been heated to redness will denote their quantities. 
“ Should any magnesia and lime have escaped solution in the muri- 
atic acid, they will be found in the sulphuric acid; this, however, is 
ANALYSIS OF SOILS. 
619 COMPOSITION OF SOILS. 
rarely the case ; but the process for detecting them, and ascertaining 
their"quantities, is the same in both instances. 
“ The method of analysis by sulphuric acid, is sufficiently precise 
for all usual experiments ; but if very great accuracy be an object, 
dry carbonate of potassa must be employed as the agent, and the resi- 
duum of the incineration (6) must be heated red for a half hour, with 
four times its weight of this substance, in a crucible of silver, or of 
well baked porcelain. The mass obtained must be dissolved in muri- 
atic acid, and the solution evaporated till it is nearly solid ; distilled 
water must then be added, by which the oxide of iron and all the 
earths, except silica, will be dissolved in combination as muriates. The 
silica, after the usual process of lixiviation, must be heated red ; the 
other substances may be separated in the same manner as from the mu- 
riatic and sulphuric solutions. 
“ This process is the one usually employed by chemical philosophers 
for the analysis of stones. 
“ 8. If any saline matter, or soluble vegetable or animal matter is 
suspected in the soil, it will be found in the water of lixiviation used 
for separating the sand. 
“ This water must be evaporated to dryness in a proper dish, at a 
heat below its boiling point. 
“ If the solid matter obtained is of a brown colour and inflammable, 
it may be considered as partly vegetable extract. If its smell, when 
exposed to heat, be like that of burnt feathers, it contains animal oV 
albuminous matter ; if it be white, crystalline, and not destructible by 
heat, it may be considered as principally saline matter. 
“ 9. Should sulphate or phosphate of lime be suspected in the entire 
soil, the detection of them requires a particular process upon it. A 
given weight of it, for instance, 400 grains, must be heated red for half 
an hour in a crucible, mixed with one-third of powdered charcoal. 
The mixture must be boiled for a quarter of an hour, in a half pint of 
water, and the fluid collected through the filter, and exposed for some 
days to the atmosphere in an open vessel. If any notable quantity of 
sulphate of lime (gypsum) existed in the soil, a white precipitate will 
gradually form in the fluid, and the weight of it will indicate the pro- 
portion. 
“ Phosphate of lime, if any exist, may be separated from the soil 
after the process for gypsum. Muriatic acid must be digested upon the 
soil, in quantity more than sufficient to saturate the soluble earths ; the 
solution must be evaporated, and water poured upon the solid matter. 
This fluid -will dissolve the compounds of earths with the muriatic acid, 
and leave the phosphate of lime untouched. 
“ It would not fall within the limits assigned to this Lecture, to detail 
any processes for the detection of substances which may be accidentally 
mixed with the matters of soils. Other earths and metallic oxides are 
now and then found in them, but in quantities too minute to bear any 
relation to fertility or barrenness, and the search for them would make 
the analysis much more complicated without rendering it more useful. 
“ 10. When the examination of a soil is completed, the product? 
should be numerically arranged, and their quantities added together, 
and if they nearly equal the original quantity of soil, the analysis may 
be considered as accurate. It must, however, be noticed, that when 
phosphate or sulphate of lime are discovered by the independent pro- COMPOSITION OP SOILS. 
621 
cess just described (9), a correction must be made for the general pro- 
cess, by subtracting a sum equal to their weight from the quantity of 
carbonate of lime, obtained by precipitation from the muriatic acid. 
“ In arranging the products, the form should be in the order of the 
experiments by which they were procured. 
“ Thus, I obtained from 400 grains of a good siliceous sandy soil, 
from a hop garden near Tunbridge, Kent, 
Of water of absorption 
— loose stones and gravel principally siliceous 
— undecompounded vegetable fibres 
— fine siliceous sand 
Of minutely divided matter separated by agitation and fil- 
tration, and consisting of 
Carbonate of lime 19 
Carbonate of magnesia 3 
Matter destructible by heat, principally vegetable . . 15 
Silica 21 
Alumina 13 
Oxide of iron 5 
Soluble matter, principally common salt and vegetable 
extract 3 
fivnmim . * 2 
Grains. 
19 
53 
14 
212 
— 
8! 
Amount of all the products 
379 
Loss 
21 
“ The loss in this analysis is not more than usually occurs, and it de- 
pends upon the impossibility of collecting the whole quantities of the 
different precipitates ; and upon the presence of more moisture than 
is accounted for in the water of absorption, and which is lost in the dif- 
ferent processes. 
“ When the experimenter is become acquainted with the use of the 
different instruments, the properties of the re-agents, and the relations 
between the external and chemical qualities of soils, he will seldom 
find it necessary to perform, in any one case, all the processes that have 
been described. When his soil, for instance, contains no notable pro- 
portion of calcareous matter, the action of the muriatic acid (7) may be 
omitted. In examining peat soils, he will principally have to attend to 
the operation by fire and air (8) ; and in the analysis of chalks and 
loams, he will often be able to omit the experiment by sulphuric acid 
(9)- 
“ In the first trials that are made by persons unacquainted with 
chemistry, they must not expect much precision of result. Many dif- 
ficulties will be met with : but in overcoming them, the most useful 
kind of practical knowledge will be obtained ; and nothing is so in- 
structive in experimental science, as the detection of mistakes. The 
correct analyst ought to be well grounded in general chemical informa- 
tion ; but, perhaps, there is no better mode of gaining it, than that of 
attempting original investigations. In pursuing his experiments, he 
will be continually obliged to learn the properties of the substances he 
is employing or acting upqa ; and bis theoretical ideas will be more va- COMPOSITION OP SOILS. 
luable in being connected with practical operations, and acquired for 
the purpose of discovery. 
“ Plants being possessed of no locomotive powers, can grow only in 
places where they are supplied with food ; and the soil is necessary to 
their existence, both as aff ording them nourishment,and enabling them to 
fix themselves in such a manner as to obey those mechanical laws by 
which tlieir radicles are kept below the surface, and their leaves ex- 
posed to the free atmosphere. As the systems of roots, branches, and 
leaves, are very different in different vegetables, so they flourish most 
in different soils ; the plants that have bulbous roots require a looser 
and a lighter soil than such as have fibrous roots ; and the plants pos- 
sessing only short fibrous radicles demand a firmer soil than such as 
have tap roots, or extensive lateral roots. 
“ A good turnip soil fromHolkham, Norfolk, afforded me eight parts 
out of nine siliceous sand ; and the finely-divided matter consisted 
Of carbonate of lime . 
. . 63 
— silica 
— alumina 
—. oxide of iron 
— vegetable and saline matter . 
• , 
. . 5 
— moisture . 
“ I found the soil taken from a field at Sheffield-plactf, in Sussex, re- 
markable for producing flourishing oaks, to consist of six parts of sand, 
and one part of clay and finely-divided matter. And 100 parts of the 
entire soil, submitted to analysis, produced. 
Silica 
Parts. 
. 54 
Alumina 
. 28 
Carbonate of lime 
Oxide of iron 
5 
Decomposing vegetable matter . . 
4 
Moisture and loss 
. 3 
“ An excellent wheat soil, from the neighbourhood of West Dray- 
ton, Middlesex, gave three parts in five of siliceous sand ; and the fine- 
ly-divided matter consisted of 
Carbonate of lime 
28 
Silica 
32 
Alumina 
29 
Animal or vegetable matter and moisture 
11 
“ Of these soils the last was by far the most, and the first the least, 
coherent in texture. In all cases the constituent parts of the soil 
which give tenacity and coherence are the finely-divided matters ; and 
they possess the power of giving those qualities in the highest degree 
when they contain much alumina. A small quantity of finelv-divided 
matter is sufficient to fit a soil for the production of turnips and barley ; 
and I have seen a tolerable crop of turnips on a soil containing 11 parts 
out ol 12 sand. A much greater proportion of sand, however, always 
produces absolute sterility. The soil of Bagshot heath, which is en- 
tirely devoid of vegetable covering, contains less than of finely-di- 
vided matter. 400 parts of it, which had been heated red, afforded 
me. 380 parts of coarse siliceous sand, nine parts of fine siliceous sand. 623 
and 11 parts of impalpable matter, which was a mixture of ferruginous 
clay, with carbonate of lime. Vegetable or animal matters, when fine- 
ly-divided, not only give coherence, but likewise softness and penetra- 
bility ; but neither they nor any other part of the soil must be in too 
great proportion ; and a soil is unproductive if it consist entirely of 
impalpable matters. 
“ Pure alumina or silica, pure carbonate of lime, or carbonate of 
magnesia, are incapable of supporting healthy vegetation. 
“ No soil is fertile that contains as much as 19 parts out of 20 of any 
of the constituents that have been mentioned. 
“ It will be asked, are the pure earths in the soil merely active as 
mechanical or indirect chemical agents, or do they actually afford food 
to the plant ? This is an important question ; and not difficult of solu- 
tion. 
“ The earths consist, as I have before stated, of metals united to ox- 
ygen ; and these metals have not been decomposed ; there is conse- 
quently no reason to suppose that the earths are convertible into the 
elements of organized compounds, into carbon, hydrogen, and azote. 
“ Plants have been made to grow in given quantities of earth. 
They consume very small portions only ; and what is lost may be 
accounted for by the quantities found in their ashes ; that is to say, it 
has not been converted into any new products. 
“ The carbonic acid united to lime or magnesia, if any stronger 
acid happens to be formed in the soil during the fermentation of vege- 
table matter which will disengage it from the earths, maybe decompos- 
ed ; but the earths themselves cannot be supposed convertible into 
other substances, by any process taking place in the soil. 
“ In all cases the ashes of plants contain some of the earths of the 
soil in which they grow ; but these earths, as may be seen from the 
table of the ashes afforded by different plants given in the last Lec- 
ture*, never equal more than of the weight of the plant consumed. 
“ If they be considered as necessary to the vegetable, it is as giving 
hardness and firmness to its organization. Thus, it has been mention- 
ed that wheat, oats, and many of the hollow grasses, have an epiderm- 
is principally of siliceous earth ; the use of which seems to be to 
strengthen them, and defend them from the attacks of insects and pa- 
rasitical plants. 
“ Many soils are popularly distinguished as cold; and the distinction, 
though at first view it may appear to be founded on prejudice, is really 
just. 
“ Some soils are much more heated by the rays of the sun, all other 
circumstances being equal, than others ; and soils brought to the same 
degree of heat cool in different times, i. e. some cool much faster than 
others. 
“ This property has been very little attended to in a philosophical 
point of view ; yet it is of the highest importance in agriculture. In 
general, soils that consist principally of a stiff white clay are difficultly 
heated ; and being usually very moist they retain their heat only for a 
short time. Chalks are similar in one respect, that they are difficultly 
heated ; but being drier they retain their heat longer, less being 
consumed in causing the evaporation of their moisture. 
TEMPERATURE OF THE SOIL. 
* See Sir Humphry Davy’s Elements of Agricultural Chemistry, 4to., p. 102.- 624 
HUMIDITY OF THE SOIL. 
“ A black soil, containing much soft vegetable matter, is most heated 
by the sun and air; and the coloured soils, and the soils containing 
much carbonaceous matter, or ferruginous matter, exposed under 
equal circumstances to sun, acquire a much higher temperature than 
pale-coloured soils. 
“ When soils are perfectly dry, those that most readily become 
heated by the solar rays likewise cool most rapidly; but 1 have ascer- 
tained by experiment, that the darkest-coloured dry soil (that which 
contains abundance of animal or vegetable matter, substances which 
most facilitate the diminution of temperature,) when heated to the 
same degree, provided it be within the common limits of the effect of 
solar heat, will cool more slowly than a wet pale soil entirely composed 
of earthy matter. 
“ I found that a rich black mould, which contained nearly of ve- 
getable matter, had its temperature increased in an hour from 65° to 
88° by exposure to sunshine ; whilst a chalk soil was heated only to 
69° under the same circumstances. But the mould, removed inio the 
shade, where the temperature was 62°, lost, in half an hour, 15° ; 
whereas the chalk, under tlie same circumstances, had lost only 4°. 
“ Brown fertile soil, and a cold barren clay were each artificially 
heated to 88°, having been previously dried ; they were then exposed 
in a temperature of 57° ; in half an hour the dark soil was found to 
have lost 9° of heat; the clay had lost only 6°. An equal portion of 
the clay containing moisture, after being heated to 88°, was exposed in 
a temperature of 55° ; in less than a quarter of an hour it was found 
to have gained the temperature of the room. The soils in all these 
experiments were placed in small tin-plate trays, two inches square and 
half an inch in depth ; and the temperature ascertained by a delicate 
thermometer. 
“ Nothing can be more evident, than that the genial heat of the soil, 
particularly in spring, must be of the highest importance to the rising 
plant. And when the leaves are fully developed, the ground is shad- 
ed ; and any injurious influence, which in the summer might be ex- 
pected from too great a heat, entirely prevented : so that the tempera- 
ture of the surface, when bare and exposed to the rays of the sun, 
affords at least one indication of the degrees of its fertility; and the 
thermometer may be sometimes a useful instrument to the purchaser 
or improver of lands. 
“ The moisture in the soil influences its temperature ; and the 
manner it which it is distributed through, or combined with, the ear- 
thy materials, is of great importance in relation to the nutriment of the 
plant. If water is too strongly attracted by the earths, it will not be 
absorbed by the roots of the plants ; if it is in too great quantity, or 
too loosely united to them, it tends to injure or destroy the fibrous 
by parts of the roots. 
“ There are two states in which water seems to exist in the earths, 
and in animal and vegetable substances ; in the first state it is united 
chemical, in the other by cohesive, attraction. 
“ If pure solution of ammonia or potassa be poured into a solution 
of alum, alumina falls down combined with water ; and the powder dried 
by exposure to air will afford more than half its weight of water by 
distillation ; in this instance the water is united by chemical attraction. 
The moisture which wood, or muscular fibre, or gum, that have been heated to 212°, afford by distillation at a red heat, is likewise water, 
the elements of which were united in the substance by chemical com- 
bination. 
“ When pipe-clays dried at the temperature of the atmosphere, is 
brought in contact with water, the fluid is rapidly absorbed ; this is 
owing to cohesive attraction. Soils in general, vegetable, and animal 
substances, that have been dried at a heat below that of boiling water, 
increase in weight by exposure to air, owing to their absorbing water 
existing in the state of vapour in the air, in consequence of cohesive 
attraction. 
“ The water chemically combined amongst the elements of soils, unless 
in the case of the decomposition of animal or vegetable substances, can- 
not be absorbed by the roots of plants ; but that adhering to the parts 
of the soil is in constant use in vegetation. Indeed there are few mix- 
tures of the earths found in soils that contain any chemically combined 
water ; water is expelled from the earths by most substances that com- 
bine with them. Thus, if a combination of lime and water be exposed 
to carbonic acid, the carbonic acid takes the place of water, and com- 
pounds of alumina and silica, or other compounds of the earths, do not 
chemically unite with water ; and soils, as it has been stated, are 
formed either by earthy carbonates, or compounds of the pure earths 
and metallic oxides. 
“ When saline substances exist in soils, they may be united to water 
both chemically and mechanically ; but they are always in too small a 
quantity to influence materially the relations of the soil to water. 
“ The power of the soil to absorb water by cohesive attraction, de- 
pends in great measure upon the state of division of its parts ; the more 
divided they are, the greater is their absorbent power. The different 
constituent parts of soils likewise appear to act, even by cohesive at- 
traction, with different degrees of energy. Thus vegetable substances 
seem to be more absorbent than animal substances ; animal substances 
more so than compounds of alumina and silica ; and compounds of alu- 
mina and silica more absorbent than carbonates of lime and magnesia ; 
these differences may, however, possibly depend upon the differences 
in their state of division, and upon the surface exposed. 
“The power of soils to absorb w’ater from air, is much connected 
with fertility. When this power is great, the plant is supplied with 
moisture in dry seasons ; and the eftect of evaporation in the day is 
counteracted by the absorption of aqueous vapour from the atmos- 
phere, by the interior parts of the soil during the day, and by both the 
exterior and interior during night. 
“ The stiff clays approaching to pipe-clays in their nature, which 
take up the greatest quantity of Water when it is poured upon them in 
a fluid form, are not the soils which absorb most moisture from the at- 
mosphere in dry weather. They cake, and present only a small sur- 
face to the air, and the vegetation on them is generally burnt up almost 
as readily as on sands. 
“ The soils that are most efficient in supplying the plant with water 
by atmospheric absorption, are those in which there is a due mixture 
of sand, finely-divided clay, and carbonate of lime, with some animal 
or vegetable matter ; and which are so loose and light as to be freely 
permeable to the atmosphere. With respect to this quality, carbonate 
'of lime and animal and vegetable matter are of great use in soils ; they 
IK REGARD TO MOISTURE. CAUSES OF THE RELATIVE 
give absorbent power to the soil without giving it likewise tenacity ; 
sand, which also destroys tenacity, on the contrary, gives little absorb- 
ent power. 
“ I have compared the absorbent powers of many soils with respect 
to atmospheric moisture, and I have always found it greatest in the most 
fertile soils ; so that it affords one method of judging of the productive- 
ness of land. 
“ 1000 parts of a celebrated soil from Ormiston, in East Lothian, 
which contained more than half its weight of finely-divided matter, of 
which 11 parts were carbonate of lime, and 9 parts vegetable matter, 
when dried at 212°, gained in an hour by exposure to air, saturated 
with moisture, at temperature 62°, 18 grains. 
“ 1000 parts of a very fertile soil from the banks of the river Par- 
ret, in Somersetshire, under the same circumstances, gained 16 grains. 
“ 1000 parts of a soil from Mersea, in Essex, worth 45 shillings an 
acre, gained 13 grains. 
“ 1000 grains of a fine sand from Essex, worth 28 shillings an acre, 
gained 11 grains. 
“ 1000 of a coarse sand, worth 15 shillings an acre, gained only eight 
grains. 
“ 1000 of the soil of Bagshot-heath gained only three grains. 
“ Water, and the decomposing animal and vegetable matter existing 
in the soil, constitute the true nourishment of plants ; and as the earthy 
parts of the soil are useful in retaining water, so as to supply it in the 
proper proportions to the roots of the vegetables, so they are likewise 
efficacious in producing the proper distribution of the animal or vege- 
table matter ; when equally mixed with it they prevent it from decom- 
posing too rapidly ; and by their means the soluble parts are supplied 
in propei1 proportions. 
“ Besides this agency, which maybe considered as mechanical, there 
is another agency between soils and organizable matters, which may be 
regarded as chemical in its nature. The earths, and even the earthy 
carbonates, have a certain degree of chemical attraction for many of 
the principles of vegetable and animal substances. This is easily ex- 
emplified in the instance of alumina and oil; if an acid solution of alu- 
mina be mixed with a solution of soap, which consists of oily matter 
and potassa, the oil and the alumina will unite and form a white powder, 
which will sink to the bottom of the fluid. 
“ The extract from decomposing vegetable matter when boiled with 
pipe-clay or chalk, forms a combination by which the vegetable matter 
is rendered more difficult of decomposition and of solution. Pure si- 
lica and siliceous sands have little action of this kind ; and the soils 
which contain the most alumina and carbonate of lime, are those which 
act with the greatest chemical energy in preserving manures. Such 
soils merit the appellation which is commonly given to them of rich soils ; 
for the vegetable nourishment is long preserved in them, unless taken 
up by the organs of plants. Siliceous sands, on the contrary, deserve 
the term hungry, which is commonly applied to them ; for the vegeta- 
ble and animal matters they contain not being attracted by the earthy 
constituent parts of the soil, are more liable to be decomposed by the 
action of the atmosphere, or carried off from them by water. 
“ In most of the black and brown rich vegetable moulds, the earths 
seem to be in combination with a peculiar extractive matter, afforded FERTILITY OF SOILS. 
during the decomposition of vegetables : this is slowly taken up, or 
attracted from the earths by water, and appears to constitute a prime 
cause of the fertility of the soil. 
“ The standard of fertility of soils for different plants must vary 
with the climate ; and must be particularly influenced by the quantity 
of rain. 
“ The power of soils to absorb moisture ought to be much greater 
in warm or dry countries, than in cold and moist ones ; and the quan- 
tity of clay, or vegetable or animal matter they contain, greater. Soils 
also on declivities ought to be more absorbent than in plains or in the 
bottom of valleys. Their productiveness likewise is influenced by 
the nature of the subsoil or the stratum on w hich they rest. 
“ When soils are immediately situated upon a bed of rock or stone, 
they are much sooner rendered dry by evaporation, than where the 
subsoil is of clay or marl; and a prime cause of the great fertility of 
the land in the moist climate of Ireland, is the proximity of the rocky 
strata to the soil. 
“ A clayey subsoil will sometimes be of material advantage to a sandy 
soil; and in this case it will retain moisture in such a manner as to be 
capable of supplying that lost by the earth above, in consequence of 
evaporation, or the consumption of it by plants. 
“ A sandy or gravelly subsoil, often corrects the imperfections of too 
great a degree of absorbent power in the true soil. 
“ In calcareous countries, where the surface is a species of marl, 
the soil is often found only a few inches above the limestone ; and its 
fertility is not impaired by the proximity of the rock ; though in a less 
absorbent soil, this situation would occasion barrenness ; and the sand- 
stone and limestone hills in Derbyshire and North Wales may be easily 
distinguished at a distance in summer by the different tints of the ve- 
getation. The grass on the sandstone hills usually appears brown and 
burnt up ; that on the limestone hills, flourishing and green. 
“ In devoting the different parts of an estate to the necessary crops, 
it is perfectly evident from what has been said, that no general princi- 
ple can be laid down, except when all the circumstances of the nature, 
composition, and situation of the soil and subtil are known. 
“ The methods of cultivation likewise must be different for differ- 
ent soils. The same practice which will be excellent in one case may 
be destructive in another. 
“ Deep ploughing may be a very profitable practice in a rich thick 
soil; and in a fertile shallow soil, situated upon cold clay or sandy sub- 
soil, it may be extremely prejudicial. 
“ In a moist climate where the quantity of rain that falls annually 
equals from 40 to 60 inches, as in Lancashire, Cornwall, and some parts 
of Ireland, a siliceous sandy soil is much more productive than in dry 
districts ; and in such situations wheat and beans will require a less co- 
herent and absorbent soil than in drier situations ; and plants, having 
bulbous roots, will flourish in a soil containing as much as 14 parts 
out of 15 of sand. 
“ Even the exhausting powers of crops will be influenced by like 
circumstances. In cases where plants cannot absorb sufficient mois- 
ture. they must take up more manure. And in Ireland, Cornwall, and 
the western Highlands of Scotland, corn will exhaust less than in dry 
inland situations. Oats, particularly in dry climates, are impoverish- 
ing ip a much higher degree than in moist ones.” APPENDIX, 
EQUIVALENT NUMBERS OF VEGETABLE AND ANIMAL PRODUCTS, 
AND THEIR COMBINATIONS. 
CONTAINING EQUIVALENT NUMBERS, fa. 
TABULAR VIEW 
OF THE 
EQUIVALENT NUMBERS OF VEGETABLE AND ANIMAL PRODUCTS, AND 
. THEIR COMBINATIONS. 
SUBSTANCES 
Equivalent 
Number 
COMPOSITION 
I. Gum 
90? 
Bigummafe of lead 
292 
180 gum.+112 ox. of lead. 
II. Sugar 
81? 
Saccharate of lead 
192 
81 sugar +112 ox. of lead. 
III. Starch 
144? 
Binamilate of lead . 
400 
288 starch+112 ox. of lead. 
IV. Tannin 
215.3? 
Tannate of lead 
327.3 
215.3 tannin + 112 ox. of lead. 
V. Wax 
146? 
VI. Oil? 
VII. Camphoric acid? 
VIII. Succinic acid 
60? 
Succinate of ammonia 
67 
50 S. A.+ 17 ammcuL 
potassa 
98 
50 S. A.+ 48 P. 
soda 
82 
50 S. A.+32S. 
lime 
78 
50 S. A.+ 28 L. EQUIVALENT NUMBERS, 4"C. 
Equivalent Numbers, fyc. (continued.) 
SUBSTANCES 
Equivalent 
Number 
COMPOSITION 
Succinate of baryta 
128 
50 S. A. + 78 B. 
strontia 
102 
50 S. A. + 52 S. 
f magnesia 
70 
50 S. A.-|-20 M. 
manganese 
86 
50 S. A.+36 O. M. 
— iron 
86 
50 S. A.+36 O. I. 
zinc 
92 
50 S. A.+42 0. Z. 
tin 
117 
50 S. A.+67 O. T. 
copper? 
122 
50 S. A.+ 72 O. C. 
lead 
162 
50 S. A.+ 112 O. L. 
IX. Morphia 
324? 
X. Meconic acid 
23? 
XI. Strichnia 
381? 
XII. Brucia? 
XIII. Delphia? 
XIV. Mellitic acid ? 
XV. Tartaric acid 
67 
Tartrate of ammonia 
84 
67 T. A.+ 17 Amin. 
potassa 
115 
67 T. A.+48P. 
Bi-tartrate of potassa 
182 
134 T. A. +48 P. 
Tartrate of potassa and ampionia 
199 
134 T. A.+48P + 17 Amm. 
—— soda 
99 
67 T. A. +32 S. 
potassa and soda 
214 
134 T. A.+ 32 S. + 48P. EQUIVALENT1 NUMBERS, #C. 
Equivalent Numbers, fyc. (continued.) 
SUBSTANCES. 
Equivalent 
Number 
COMPOSITION. 
95 
67 T. A.+ 28 L. 
134 T. A.+28 L. +48 p. 
and potassa 
210 
baryta 
145 
67 T. A.+ 78 B. 
119 
87 
67 T. A.+52 S. 
67 T. A.+ 20 M. 
magnesia 
manganese 
103 
67 T. A.+36 O. M. 
iron 
103 
67 T. A.+36 O. I. 
and potassa 
218 
134 T. A.+ 36 O. I.+48 P. 
zinc 
109 
67 T. A. +42 O. Z. 
tin 
134 
67 T. A.+ 67 0. T. 
and potassa 
249 
134 T. A.+ 67 0. T.+48 P. 
copper 
214 
134 T. A. +80 perox. C. 
lead 
179 
67 T. A.+ 112 0. L. 
■ and potassa 
294 
134 T. A.+ 112 0. L.+48P. 
antimony 
123 
67 T. A.+ 56 0. A. 
— and potassa 
238 
134 T. A.+ 56 0. A.+48 P. 
bismuth 
147 
67 T. A.+ 80 0. B. 
cobalt 
107.5 
67 T. A.+ 40.5 0. C. 
uranium ? 
titanium ? 
* 
• cerium ? 
nickel 
104.6 
67 T. A. +37.6 0. N. 
mercury 
and potassa 
275 
390 
67 T. A. +208 0. M. 
134 T. A. +208 0. M. +48 P. 
silver 
184.3 
67 T. A.+117.3 0. S. 
silver and potassa 
299.3 
134 T. A. +117.3 0. S.+48 P. EQUIVALENT NUMBERS, •S'C. 
Equivalent Numbers. &rc. (continued.) 
SUBSTANCES. 
Equivalent 
Number. 
COMPOSITION. 
XVI. Oxalic Acid 
38.? 
Oxalate of ammonia. 
55 
38 O. A.+ 17 Am. 
potassa 
86 
38 O. A.+ 48 P. 
soda 
70 
38 0. A. + 32S. 
lime 
66 
38 0. A.+28 L. 
■ baryta 
116 
38 0. A. + 78 B. 
- - strontia 
90 
38 0. A. + 52 S. 
magnesia 
58 
38 0. A. + 20 M. 
manganese 
74 
38 0. A. + 36 0. M. 
iron 
74 
38 0. A.+36 0. I. 
— zinc 
80 
38 0. A. -1- 42 0. Z. 
— - tin 
105 
38 0. A.+67 O. T. 
———— copper 
156 
76 0. A. + 80 Perox. C. 
—- ■ ■ ■ ■— and ammonia 
211 
156 Ox. Cop.+55 Oxal. am. 
and potassa 
242 
156 Ox. Cop.+ 86 Ox. Pot. 
and soda 
226 
156 Ox. Cop.+ 70 Ox. Sod. 
lead 
150 
38 O. A. + 112 O. L. 
antimony 
94 
38 O. A. +56 0. Ant. 
■ bismuth 
118 
38 0. A. + 80 O. B. 
•■ ■ ■ cobalt 
78.5 
38 0. A.+40.5 0. C. 
uranium ? 
- nickel 
756 
38 0. A.+37.6 0. N. 
mercury 
246 
38 0. A.+ 208 0. M. 
silver 
155.3 
38 0. A.+ 117.3 0. S. 
XVII. Citric Acid . 
59? EQUIVALENT NUMBERS, 4*C. 
Equivalent, Numbers, 4*c. (continued.) 
SUBSTANCES. 
Equivalent 
Number 
COMPOSITION. 
Citrate of ammonia 
76 
59 C. A.+ 17 Am. 
■»—. potassa 
107 
59 C. A.+48P. 
— -• soda .. 
91 
59 C. A.+32 S. 
lime 
87 
59 C. A.+28 L. 
baryta 
137 
59 C. A.+ 78 B. 
strontia 
111 
59 C. A. +52 S. 
magnesia 
79 
59 C. A. +20 M. 
■ manganese 
95 
59 C. A.+36 0. M. 
• iron 
95 
59 C. A. +36 0.1. 
zinc 
101 
59 C. A.+ 42 0. Z. 
tin 
i26 
59 C. A.+67 0. T. 
copper 
198 
118 C. A.+ 80 per ox. C. 
lead 
171 
59 C. A.+ 112 0. L. 
• ■ antimony? 
■ ■■ bismuth 
139 
59 C. A.+80 0. B. 
cobalt 
99.5 
59 C. A.+40.5 0. C. 
• uranium? 
nickel 
96.6 
59 C. A.+37.6 0. N. 
r mercury 
267 
59 C. A.+208 0. M. 
— silver 
176.3 
59 C. A.+117.3 0. S. 
XVIII. Malic Acid 
71.1? 
XIX. Gallic Acid 
64.3? 
XX. Benzoic Acid < • • • 
119? 
Benzoate of ammonia 
136 
119 B. A.+17 Aram. 
potassa . 
1 
167 
119 B. A.+48 P. equivalent Lumbers, &c. 
Equivalent Numbers, (continued.) 
SUBSTANCES. 
Equivalent 
Number. 
COMPOSITION. 
Benzoate of soda 
51 
( 
119 B. A.+32S. 
lime 
147 
119 B. A. + 28L. 
baryta 
197 
119 B. A.+ 78 B. 
lead 
231 
119 B. A.+ 112 0. L. 
XXI. Acetic Acid . .. 
51.5? 
Acetate of ammonia 
68.5 
51.5 A. A.+ 17 Aim 
potassa 
99.5 
51.5 A. A.+48 P. 
$oda 
83.5 
51.5 A. A. +32 S. 
lime 
79.5 
51.5 A. A.+28 L. 
baryta 
129.5 
51.5 A. A.+ 78 B. 
strontia 
103.5 
51.5 A. A.+ 52 S. 
— magnesia 
71.5 
51.5 A. A.+20 M. 
manganese 
87.5 
51.5 A. A.+36 0. M. 
iron 
87.5 
51.5 A. A.+36 0.1. 
— zinc 
93.5 
51.5 A. A.+ 42 0. Z. 
tin 
118.5 
51.5 A. A.+67 0. T. 
copper 
183 
103 A. A.+80 Perox. C. 
lead 
163.5 
51.5 A. A.+112 0. L. 
bismuth 
131.5 
51.5 A. A.+80 0. B. 
—mercury 
259.5 
51.5 A. A.+208 0. M. 
silver 
168.8 
51.5 A. A.+117.3 0. S. 
— alumina ? 
XXII. Formic Acid ? . . .. Probably a compound of Ma 
ic and Acetic Acids. 
XXIII. Uric Acid? 
35? 637 
Note to Sect. 46—p. 17. 
* Two years ago, when Mr. Brande published the first edition of his Manual, the atomic theory could 
not well be represented as an independent collection of facts, and much less can it be considered so at 
present. The doctrine of definite proportions is now satisfactorily established, and the ratio of combining 
quantities is found to proceed in such regular progression that many of the phenomena of Chemistry may 
be submitted to calculation, and some of its abstrusest parts elucidated upon mathematical principles. 
A very important law has been found to govern Chemical combinations, in virtue of which, when bodies 
combine in different proportions, the larger proportion of one of the ingredients has a simple arithmetical 
ratio to the lesser proportion: The second quantity being a simple multiple of the first, and if there is a 
third or fourth proportion, the same ratio continues between them. If 100 of a combine in the first pro- 
portion with 8 of b, in the second proportion 100 of a will combine with 16 of b, in the third with 24, in 
the fourth with 32; these proportions having to each other the simple ratio of 1, 2, 3, 4. 
The operation of this principle appeared with striking and instructive evidence in the tables of Dr. 
Richter. They were formed from a series of numerous experiments on the reciprocal decomposition of 
salts, and show the weight of each base capable of saturating one hundred parts of each acid; and the 
weight of each acid, capable of saturating one hundred of each base. He threw the results into tables, 
and observed that in all, the bases and the acids followed the same order: and further that the numbers 
in each table constitute a series, having the same ratio to each other in all the tables. Thus supposing in 
the table of sulphates, one hundred parts of acid were saturated by one hundred of soda, two hundred of 
potassa and three hundred of baryta; then in the table of nitrates the same ratio would hold good, and 
the soda, potassa and baryta, would there also stand to each other in the relation of one, two and three. 
Thus was explained, why when two neutral salts decompose each other, the newly formed salts are also 
neutral; for the same proportion of the bases that saturate a given weight of one acid will saturate a given 
weight also of all the other acids. Hence numbers may be attached to each acid and to each base, indi- 
cating the weight of it, which will saturate the numbers attached to all the other acids and bases. Upon 
this principle elementary works on Chemistry contain tables of the representative numbers of bodies. 
Mr. Higgins in 1789, published that Chemical attraction only prevailed between the ultimate particles 
of simple elementary matter, and between compound atoms. Mr. Dalton in 1804 greatly developed and 
improved this doctrine, and since then some of the most eminent Chemical philosophers have directed their 
attention to the definite proportions in which bodies unite that form several compounds. Seventy parts of 
potash, for example, unite to thirty of carbonic acid, and to sixty, but not to any intermediate proportions, 
when two bodies combine only in one proportion, the most simple supposition is, that they combine atom 
to atom singly, that is, one atom of the one with one atom of the other; when they combine in two pro- 
portions, it may be supposed that the first combination is that of one atom of the one with one atom of the 
other; and the second that of one atom of the one with two of the other; in the third of one atom with 
three, &c.; and no combinations in proportions different from these will exist. 
The same law was inferred by Dr. Wollaston, from the investigation of certain saline compounds. He 
had observed, that when they are partially decomposed, the quantity of one of the ingredients abstracted 
is exactly half the quantity of it which the compound contains. In producing, for example, the partial 
decomposition, by heat, of the compound of potash with carbonic acid, a certain quantity of carbonic 
acid is expelled from it; and in submitting it after this to a more powerful decomposing force, that of the 
action of a strong acid, another quantity of carbonic acid is expelled, which is exactly equal to the 
former; apparently proving that the potash combines with the carbonic acid in two proportions, of which 
the one is just double the other. 
Gay-Lussac afterwards observed a relation in the combinations of aerial bodies with each other, which 
is obviously the result of the same law. It had been remarked in some few cases, that gases combine in 
simple proportions; for example, of equal volumes, or of two volumes of one with one volume of another. 
This last case had in particular been observed in the combination of the elements of water. This induced 
him to examine other combinations of this class of bodies, and his investigations led to the general conclu- 
sion, that bodies in the aerial form combine in most simple, those of 1 to 1, of 1 to 2, or of 1 to 
3, &c. in volumes. 
This view of the subject has one peculiarity. When the proportions of the elements of a compound 
are estimated by weight, there is no simple expressible proportion between them in the first combination. 
It is only when there is a second combination of the same elements, that the additional portion of one of 
them is a multiple of the first: but in elastic fluids, even in the first combination, the two elements have a 
certain simple proportion to each other. 
Berzelius has generalized the view given by Gay-Lussac. Every body is convertible, or may be sup- 
posed convertible, into the gaseous state; and all bodies, he supposes, combine in simple proportions, 
estimated by volume, in the elastic form. Under this modification, it constitutes what he calls the theory 
of volumes. 
Another relation still more important and more comprehensive was brought forward by Mr. Daltdh. 
If it be admitted, that in the combination of two bodies in certain proportions, they unite atom with 
atom singly, or that they unite one atom with two atoms, with three, or with any number of atoms, then 
the relative weights of these atoms may be inferred from the relative quantities in which the bodies com- 
bine ; for in the case where oue body combines with another in one proportion only, and in which Mr. Dalton assumes the combination to be that of. one atom of the one with one atom of the other, the weight 
of the atoms of these bodies must be as the quantities in which th-y combine, since, by the assumption, 
these quantities respectively contain the same number of atoms. The elements of water, for example, 
oxygen and hydrogen, combine in the proportion by weight (p. 78) of 88.89 oxygen and 11.11 hydrogen, 
that is in the proportion of 8 to 1. The combination, it is supposed, consists of one atom of oxygen with 
one of hydrogen ; the number of atoms of oxygen, therefore, in the quantity of it which enters into union, 
and the number of the atoms of hydrogen in the quantity of it which combines, are the same : hence the 
weight of an atom of oxygen must be to that of an atom of hydrogen as 8 to 1. 
The weights of the atoms of bodies, it is obvious, may be equally inferred from combinations of .them 
in different proportions, if these are in simple arithmetical ratios to each other. Thus carbon forms one 
combination with oxygen in the proportion of 42.14 carbon to 57.86 oxygen nearly 5 per cent; or more 
accurately as 6 to 8. This is assumed to be what Mr. Dalton calls a binary combination, or that of one 
atom of the one body with one of the other : The weight therefore of an atom of carbon is to that «f an 
atom of oxygen as 6 to 8. But those bodies combine also in the proportion of 27.23 carbon to 72.77 oxy- 
gen, that is in the proportion of 6 to 16. This is inferred to be a compound of an atom of carbon with 
two atoms of oxygen : It equally follows from it, therefore, that the weight of an atom of carbon is to that 
of an atom of oxygen as 6 is to 8. 
In this system, altogether independent of the hypothesis of the weights of the atoms of bodies, is im- 
plied thejact, that one weight of a body, or a simple multiple of that weight, will always enter into its 
combinations in relation to certain uniform weights in which other bodies combine. The element hydro- 
gen, for example, entering into combination as 1, the element oxygen will enter into combinations in a 
quantity as 8. or some simple multiple of it; carbon as 6; sulphur as 16: that is, the quantities in which 
these bodies enter into combination will all have the relation of these numbers, or of simple multiples of 
them to 1, denoting the quantity of hydrogen, and of course will have these relations to each other. It is 
this exposition of facts which it is of so much importance to trace, whatever opinion may be formed with 
regard to the hypothesis connected with it, or assumed to explain it. 
It has been objected to the system of atomic weights that the admission of the facts does not necessarily 
lead to its adoption. It may be admitted that combination takes place between two bodies in certain 
fixed proportions, and that these have simple arithmetical ratios, the larger being a simple multiple of the 
smaller; but it does not thence follow that the first combination is that of atom with atom, and that the 
other proportions are those of one atom to two, three, or four. It is possible, that instead of attraction being 
exerted from atom to atom individually, a certain number of atoms of a body may exert the most powerful 
force, and enter into the combination it forms; and all that is strictly established is, that whatever number 
enter into the first combination, double of that number enter into the second, and three or four times the 
number into the third and fourth combinations. 
The theory of atoms, it must be confessed, is hypothetical as relates to the supposition that the weights 
of the atoms of different bodies are to each other as are the weight of an aggregation of those atoms, 
when they form the constituents of a compound. But no hypothesis can be more natural, or better con- 
nect and account for the relations of compound bodies. Nor can any thing more decisively prove the 
correctness of the theory than this, that what is objectionable in it vanishes, by simply changing the word 
atom, to another, which, without being an alteration of the sense, is a more naked expression of the fact. 
It is the suggestion of the late Dr. John Murray. 
He proposes to denote that quantity in which a body enters into combination, compared with other 
quantities in which other bodies combine, by the term combining quantity. This word will express the 
same thing (but without any hypothesis) as Mr. Dalton’s weight of an atom, or as a volume in the hypo- 
thesis of Berzelius and Gay-Lussac. And whether it denotes the weight of a single particle, or of a 
certain number of particles which always go together, it is equally proper to express the fact. 
Berthollet’s idea that the acting bodies are divided among each other, in proportions depending upon 
their relative masses and attractions, has been combated and disproved by Plaff, who has shown that 
tartrite of lime is completely decomposed, by adding to it a quantity of sulphuric acid, exactly sufficient 
to saturate the lime it contains; and in the same way he has shown that oxalate of lead is decomposed, 
by adding sulphuric acid sufficient to saturate the oxide of lead: In these cases pure tartaric and oxalic 
acids are evolved. 
The doctrine of Berthollet is inconsistent with the important law, so well established “that the larger 
portion of one of the ingredients in a Chemical compound is a simple multiple of the smaller.” When- 
ever powerful attractions operate, definite proportion* are established, and the laws with regard to them ob- 
served; but where attractions are weak, combination is either unlimited, or if it take place in certain 
proportions, these are not so invariable but that others may be formed. In those cases we will find that 
the unions are more properly mixtures than combinations. INDEX. 
A 
ATTRACTION, 1 
Affinity, 14 
Arora borealis, 51 
Acidifying principles, 65 
Apparatus, pneumatic, 67 
Acid boracic, 149 
carbonic, 130 
chlorocyanic, 146 
hydrocyanic, 147 
hydriodic, 87 
muriatic, 85 
nitric, 93 
fluoboric, 199 
vegetable, 493 
tartaric and tartrates, 493 
oxalic and oxilates, 497 
citric and citrates, 501 
malic and malates, 503 
gallic and gallates, 503 
benzoic and benzoites, 506 
acetic and acetates, 538 
ammonia, 97 
Air atmospheric, 102 
pump 103 
Atoms, connexion of their weights and spe- 
cific gravities, 161 
Antimony 248 
compounds of, 369 
Arsenic, 263 
* compounds of, 383 
Alumium, 315 
compounds of, 396 
Assay and analysis of metalliferous com- 
pounds, 327 
Analysis of mineral waters, 403 
Animal substances, 544 
Antiseptics, 545 
Animal functions, 547 
B 
BARIUM and its combinations with the fftp- 
porters of combustion, 200 
Brass, 242 
Bismuth, 371 
jBlow-pipe, 228 
Boron, 149 
Bitumens, coals, &c. 492 
Blood, 546 
Bile, 551 
Bone and shell, 564 
c 
CALORIC, properties of, 19 
Carbon, 126 
Calcium, 345 
Chlorine, 70 
Crystallization, 2 
Cadmium,, 235 
Copper, 236 
Cobalt, 258 
Cerium 260 
Chromium, 272 
Columbium, 276 
Colouring matter, 477 
Camphor, 485 
D 
DELIQUESCENCE, 3 
Dioptase, 242 
E 
EFFLORESCENCE, 3 
Equivalents, 19 
Expansion, 21 
Electricity, 33 
Eudiometers, 108 
Ethers, 531. 
F 
FLUIDS, evaporation of, 20 
F'lame, 64 
Fluxes, 329 
Fermentation, 519 
Fat, 8fc. 562 
G 
GONIOMETER, 5 
Gravity, specific, of water, 83 
Gunpowder, 180 
Gold, and compounds, 303 
Glucinum, 325 
compounds of, 400 
Gluten, 471 
Gum, 463 
Geology, 572 
H 
HEAT, or caloric. 19 
Hydrogen, 75 
combinations of, 118 RES 
ZIR 
I 
IODINE, 73 
Iron, combinations, 217 
Iridium, 293 
K 
HERMES, mineral, 251 
L 
LIGHT, 53 
Lamp, safety, 64,142 
Lithium, 190,344 
Lead, compounds, 243 
Lymph, mucus, pus, &c. 552 
M 
MATTER, radiant, 53 
Magnesium, compounds of, 209 
Manganese, compounds of, 214 
Metals, 162 
Mercury, compounds of, 282 
Menechanite, 259 
Molybdenum, 270 
Meteoric stones, 279 
Milk, 549 
Muscle, ligaments, &c. 562 
N 
NARCOTIC principles, 489 
Neutralization, 18 
Nickel, compounds of, 277 
o 
OXYGEN, 66 
Oil, fixed, 481 
volatile, 483 
Oil gas, 142 
Osmium, 292 
P 
PHOSPHORUS, 120 
Phosphorescent bodies, 62 
Potassium, combinations of, 175 
Prussian blue, 223 
Palladium, 294 
Platinum, 307 
Plants, 509 
Putrefaction, 545 
R 
RESINS, 486 
JQhodium, 293 
S 
SALT, sedative, 149 
Saturation, 18 
Sodium, combinations of, 185 
Specific gravity, manner of taking, 164 
Strontium, compounds of, 206 
Selenium, 262 
Silver, compounds of, 294 
Sugar, 414 
Sulphur, 111 
Starch, 469 
Skin, membranes, 560 
Shell and Bone, 564 
T 
THERMOMETER, 23 
Tannin, 476 
Tin, compounds of, 232 
Tellurium, 281 
Titanium, 259 
Tabular view of mineral waters, 412 
of specific gravities, and equiva- 
lent numbers, 413 
Tungsten, 274 
Thorinum, 402 
u 
URANIUM, 258 
Urin, and Urinary Calculi, 553 
V 
VEGETATION, and vegetable substctfi 
ces, 455 
w 
WATER, composition of, 78 
compressible, 83 
Weights and measures, 150 
Wax, 481 
Y 
YTTRIUM, 326 
z 
ZINC, compounds, 229 
Zafpi-e, 258 
Zirconium, 324 
compounds of, 400