At wC AN D b W: S AWT II JBp tbe same author 
Companion Text to this Outline 
INORGANIC CHEMISTRY 
Third Edition (1917), Reioritten 
925 + XVI pp. With 166 Figures 
Octavo, $2.60 net 
GENERAL CHEMISTRY 
FOR COLLEGES 
Second Edition, Entirely Rewritten 
662 + XI pp. With 138 Figures 
Octavo, $2.25 net 
NEW YORK. THE CENTURY CO. 
LONDON. GEO. BELL AND SONS. EXPERIMENTAL 
INORGANIC CHEMISTRY 
BY 
ALEXANDER SMITH 
PROFESSOR OF CHEMISTRY, AND HEAD OF THE DEPARTMENT, 
COLUMBIA UNIVERSITY 
JHftb ^Edition 
SIXTY-SIXTH 
THOUSAND 
NEW YORK 
THE CENTURY CO. 
1917 Copyright, 1907, 1917, by The Century Co. 
Copyright, 1899, by Alexander Smith 
Set up and electrotyped June, 1899 
Reprinted September, 1900 
Second Edition, Revised, October, 1902 
Reprinted August, 1905 
Third Edition, Revised, June, 1907 
Fourth Edition, Revised, January, 1908 
Reprinted August, 1908, April, 1909, January, 1910, May, 1911, 
May, 1912, October, 1912, April, 1913, April, 1914, September, 1914, 
May, 1915, May, 1916. 
Fifth Edition, Revised, January, 1917 PREFACE TO THE FIFTH EDITION 
The extensive use of the previous editions seems to have 
shown the acceptability of the general plan of the book. This 
conclusion has been confirmed by the fact that the second 
edition has been translated into German, and that translations 
of the fourth into Russian and Italian have been published. In 
the present, therefore, the fundamental features of the previous 
edition have been preserved. In brief, the aim has been to 
furnish the basis for a systematic, coherent, and instructive 
study of the elements of chemistry from the modern stand- 
point. 
In the effort to make misapprehensions and mistakes as 
nearly impossible as may be, the directions have been entirely 
rewritten, and in many cases have been amplified, and a num- 
ber of the experiments have been modified. An entirely new 
set of figures has also been drawn. To render the exercises more 
instructive, and still further to discourage mechanical work, a 
larger number of questions has been inserted. With the same 
end in view, data in regard to solubility have been introduced 
(Appendix) as a new feature, and their use in explaining chemi- 
cal phenomena has been illustrated in many experiments. 
The rationalizing value of using the conceptions of chemical 
dynamics, the electromotive series, and the degrees of ioniza- 
tion has been emphasized by more frequent references. 
Some of the formal quantitative experiments have been 
modified, and the directions have been made clearer. The 
value of these experiments has been found to lie chiefly in the 
basis they give for clear understandirig of the difficult subject 
of combining, atomic, and molecular weights. 
When quantitative experiments were first used in elementary 
chemistry it was hoped that they would also assist in develop- 
ing an abiding realization of the quantitativeness of all chem- 
ical phenomena and, as h consequence, make all the thought 
and work of the student more rigorous. In the experience of 
the author, however, quantitative experiments of the usual 
kind fail to accomplish this important result. Students who 
III IV 
PREFACE 
have performed such experiments still add a test-tube full of 
sulphuric acid to a liquid known to contain only a trace of 
a compound of lead, and still think less than a dozen bubbles 
of hydrogen sulphide sufficient to precipitate the lead from 
10 cc. of approximately normal lead nitrate solution (see 82 g 
and note 37, p. 79). They attempt to make potassium chlorate 
without considering that a few bubbles of chlorine (perhaps 
liberally mixed with air) will not saturate three grams of potas- 
sium hydroxide (see 97 a), or they take too much water and 
then, not having considered the solubilities and, therefore, 
not knowing what is wrong, throw away the product and lose 
valuable time by starting entirely ab initio. The failures which 
result from this lack of a sense of quantity are innumerable, 
and the discouragement often a serious hindrance to ultimate 
success. The fault, of course, is in the instruction, and the 
remedy lies in exercises and questions devised to cultivate 
this missing sense. It is to meet this situation that the tables 
of solubilities have been introduced and have been referred to 
frequently (see, e.g., 64, 65, 147 a, 148, 158 c-f, 160 d). With 
the same object, the tables of degrees of ionization have been 
utilized (see, e.g., 71, 73), and the varying degrees of activity 
of acids have been observed (e.g., 175). Still further to cultivate 
rational experimentation, the solutions on the side-shelf should 
be approximately normal (or in simple multiples or submulti- 
ples of this concentration), and the student may then be led to 
note the concentrations and, in many experiments, to take 
suitable quantities accordingly. The importance of the point of 
view indicated in the foregoing can hardly be overestimated. 
Genuine success in business or in the professions, and often even 
the mere making of a livelihood, depend so largely on ability 
to reason quantitatively that practice in this kind of reasoning is 
of inestimable value in education. If, on the contrary, the work 
in chemistry is purely haphazard in this respect, the study of the 
science may easily be a positive detriment rather than a benefit, 
and that whether the student ultimately makes direct use of 
his knowledge of the science or not. 
If it appears that these changes have made the work more 
difficult, it must be remembered that valuable knowledge can 
be obtained only by effort, and that the value of the knowledge 
is in proportion to the effort, provided the latter is directed 
rationally along instructive lines. Easy chemistry must be PREFACE 
V 
superficial and empirical, in proportion to its simplicity. It 
is easy to perform experiments mechanically; it is necessarily 
more difficult to interpret the results and extract all that they 
can teach. 
The book is intended for beginners in colleges, universities, 
and professional schools. It must be understood, however, 
that no one class is expected to perform all the experiments. 
Only from one-half to three-quarters of the whole material can 
be covered in thirty-three weeks, by a student working four to 
six hours a week. The author has found no difficulty in ar- 
ranging a course only twelve weeks long, and utilizing con- 
siderably less than half the contents. The outline is subdivided 
into numerous small paragraphs, so that each instructor may be 
able to make such a selection as will suit the work he desires 
to give. It is hoped that the whole body of material is suffi- 
ciently great to permit the arrangement of a course of almost 
any character. Thus, many or few quantitative experiments 
may be given, and many or few theoretical matters illustrated. 
Emphasis may be laid on work leading to analysis, or some 
of that work may be sacrificed in order to include a larger 
number of preparations. The student may even be directed 
in certain paragraphs to ignore the questions. Finally, the 
order of the experiments may be altered without serious dis- 
turbance. 
The recent great improvement in the work in chemistry in 
secondary schools makes it desirable to recognize and encour- 
age this work by outlining a different selection of experiments 
for those who have studied the science before, and to give such 
students separate class-room instruction. 
The Appendix includes also lists of apparatus and chemicals 
and other data helpful in the organization of the laboratory 
instruction. 
This outline may be employed also along with the College 
Chemistry. To facilitate this, a table at the end gives the 
equivalents of the references to pages in the Introduction to 
Inorganic Chemistry which are used exclusively in the text of 
the outline. 
In the preparation of this edition the author has received 
helpful suggestions from Prof. S. Lawrence Bigelow of the 
University of Michigan, from Prof. Ralph H. McKee of Lake 
Forest University, from Prof. H. N. McCoy of the University VI 
PREFACE 
of Chicago, from Prof. C. M. Carson of the Michigan School of 
Mines, and from Prof. T. B. Freas of Columbia University, 
as well as from many others. We wish here gratefully to ac- 
knowledge the improvements which the Outline owes to these 
suggestions. 
The Author. 
New York, 
Jan., 1917. CONTENTS. 
Chapters Pages 
General Instructions 1 
I. Manipulation 3 
II. Characteristics of Chemical Phenomena ... 10 
III. Oxygen 16 
IV. Hydrogen 23 
V. Water and Solution 28 
VI. Hydrogen Chloride and Chlorine 36 
VII. Equivalent Weights, Formula, Equations . . 41 
VIII. Bromine, Iodine, Fluorine, and their Compounds 
with Hydrogen 53 
IX. Radicals. Double Decomposition. Hydrogen 
Peroxide 61 
X. Ionization and Interactions of Acids, Bases, 
and Salts 66 
XI. Sulphur 76 
XII. Oxygen Compounds of the Halogens 89 
XIII. The Atmosphere, Nitrogen, Ammonia 94 
XIV. Oxides and Oxygen Acids of Nitrogen .... 99 
XV. Phosphorus 108 
XVI. Carbon 112 
XVII. Silicon and Boron 123 
XVIII. Metallic Elements of the Alkalies 127 
XIX. Metallic Elements of the Alkaline Earths . 134 
XX. Copper and Silver 138 
XXI. Magnesium, Zinc, Cadmium, Mercury 143 
XXII. Aluminium, Tin, Lead 148 
XXIII. Arsenic, Antimony, Bismuth 153 
XXIV. Chromium, Manganese 157 
XXV. Iron, Cobalt, Nickel 160 
Appendix 163 
VII GENERAL INSTRUCTIONS. 
Read the "Regulations" posted in the laboratory. Read also 
attentively, the following notes: 
Note 1. - Provide yourself with a note-book and make a careful 
permanent record immediately after each experiment. Enter the 
numbers and titles of the paragraphs of the outline systematically. 
State (1) what you did, if anything beyond the directions, but do 
not copy the printed directions themselves, (2) what you observed, 
(3) what conclusions you drew. A sketch of the apparatus will 
enable you to recall the circumstances of the experiment, if later 
reference to it is necessary. This note-book, when called for, is 
to be handed in for inspection. 
The blank pages in this Outline are not intended for the final 
notes. They may be used for individual suggestions given by 
the instructor, preliminary notes, record of weighings, etc. 
The directions have been expressed with the utmost care and 
brevity. Every word is significant. Italics are therefore nowhere 
employed for the purpose of emphasis. 
Note 2. - Whenever an interrogation point or a direct ques- 
tion appears, a corresponding note should appear in the note-book. 
The " (?)" indicates something to be observed and recorded. 
Note 3. - The very numerous questions asked in the course of 
this outline are intended to be answered, not by speculation, but 
by careful observation and reasoning based on the results of this. 
Very often the student will find it necessary to devise and carry 
out further experiments of his own before a satisfactory answer is 
obtained. When a question occurs to you, endeavor by reflection 
and study to answer it yourself before consulting an instructor. 
Note 4. - In many cases the work outlined could not in itself 
furnish the basis for an answer, and fuller investigation of the point 
would require work beyond the time or ability at the disposal 
of the beginner. Such questions are distinguished by an [R], 
indicating that Reference to some authority (lecture, book, or 
assistant) must be made. The number following the R is that of 
the page in Alexander Smith's Introduction to General Inorganic 
Chemistry (third edition), where the necessary information may be 
obtained. The authority should be consulted, however, only after 
the experiments have been made and the notes written up as far as 
possible. 
Note 5. - When a chemical change has been observed the equa- 
tion should always be given in the notes, but an equation alone 
is never a sufficient record. 
Note 6. - Where the word [Instructions] appears, consult the 
instructor before going further. 
Note 7. - In quantitative experiments, marked [Quant.], use the 
finer balance, in all other cases the rough scales in the laboratory. 
NOTES 1-17. 
1 2 
NOTES 1-17 
Note 8. - The expression [Storeroom] indicates that the neces- 
sary apparatus is not included in the individual outfits. 
Note 9. - When the word [Hood] appears, the operation is not 
to be conducted in the open laboratory. The apparatus is to be 
at once placed close to the desk-ventilator, or be transferred to the 
hood. 
Note 10. - Where exact quantities are not indicated, very small 
amounts of solutions (1 c.c. or less) should be taken. This advice 
is given, partly to secure saving of material, but chiefly to avoid the 
waste of time which working with large quantities always entails. 
Note 11. - To obtain the necessary chemical substances, if 
the chemicals are not furnished in "kits" to each student, do not 
carry the bottles from the side-shelf to the desk. Bring a clean 
test-tube for liquids and a watch-glass for solids. For the latter, a 
piece of the paper, provided near the side-shelf, may also be used. 
When too much of any reagent has been taken, do not return it to 
the bottle. 
Note 12. - The chemicals, if on a side-shelf, are divided into two 
sets, each arranged alphabetically according to the scientific names. 
The first set consists of solids in small bottles, the second of liquids. 
The bottles and their places are numbered consecutively to facili- 
tate accurate replacement, and scrupulous care must be taken not 
to disarrange them. Read the labels attentively, as there are 
frequently several kinds of the same substance {e.g., pure, and 
commercial, dilute, concentrated, and normal). 
All materials are supplied through the storeroom service. Do 
not therefore take side-shelf bottles, when found empty, to the 
instructor, but to the storekeeper for refilling. 
Note 13. - The expression [From Instructor], however, indi- 
cates one of a few special substances for which the student must 
apply to an instructor. 
Note 14. - The bottles on the desk, if there are any, contain 
certain substances which are frequently used. These substances 
will not be found on the side-shelf. 
Note 15. - When any acid gets upon the clothing, apply 
ammonium hydroxide solution at once. 
Note 16. - Burns, whether caused by contact with hot objects, 
by acids, or by corrosive liquids like bromine, are rubbed gently 
with a paste of sodium-hydrogen carbonate and water. All burns, 
save the slightest, must afterwards be dressed with an aqueous 
solution of boric acid (half-saturated) to prevent infection. Obtain 
the assistance of an instructor. 
Cuts must be washed in running water and dressed with boric 
acid as above, or with lanolin containing 2 per cent of boric acid. 
Note 17. - All students work independently, except where 
cooperation of two students is expressly directed. LABORATORY OUTLINE 
CHAPTER I. 
MANIPULATION. 
1. The Outfit of Apparatus. As articles missing or found 
imperfect when the course is completed will be charged for, 
check the outfit of apparatus carefully by comparison with the 
list. To do this, put all the articles on the top of the desk and 
make a mark on the margin of the list opposite to the names 
of such as you are able to identify, at the same time returning 
the article to the cupboard or drawer. With the assistance of 
an instructor, the remaining, unfamiliar articles can then be 
checked also. 
2. Instructions. 
a. Read the general instructions and notes preceding this 
chapter very carefully, and do not fail to observe them. 
b. The number of blast-lamps and balances being limited, 
the whole class cannot perform the experiments in this chapter 
simultaneously in the order given. The order is, in any case, 
a matter of indifference. Two students from the group under 
each assistant will begin with glass-working (4) or weighing 
(6 and 7 a and b). The other students will meanwhile per- 
form 3, 5, and 7 d at the desks. 
c. Record in the note-book the results of 3, 4, 6, 7, and 8. 
3. Bunsen Burner. 
a. Attach the Bunsen burner by means of rubber tubing 
to a gas connection, close the air-holes at the base, and light. 
Now open the air-holes gradually and note the effect upon the 
flame (?). Close the air-holes again, and hold a porcelain dish 
in the flame. What is deposited on the dish? What is the 
proximate cause of the difference in the two flames? When 
using the burner for heating purposes, always regulate the air 
supply so as to get a noiseless, non-luminous flame. 
b. Determine the structure of each kind of flame. Which 
parts are relatively hotter, and which cooler? This may be 
3 4 
MANIPULATION 
[§ 4 
ascertained by observing the quality of the glow produced in a 
platinum wire held across the flame in several positions. A 
match quickly inserted may also indicate the cooler portions. 
Make sketches showing the real form of the flame (?). Where 
should you hold an object in the non-luminous flame, in order 
to get the greatest heating effect. Prove the presence of un- 
burnt gas in the inner cone by inserting therein one end of a 
narrow glass tube, and igniting the gas that issues from its 
upper end (?). Which region is deficient in oxygen and which 
has an excess? The former is called the reducing, the latter 
oxidizing region. 
Sometimes the flame descends and burns noisily at the bottom 
of the tube. This happens when too much air is admitted. 
Shut off the gas, close the air-holes, turn the gas on again, and 
relight. 
c. Place in a watch-glass [Note 12, p. 2], a small quantity of 
borax* (sodium tetraborate). Heat your platinum wire, which 
has been inserted into the fused end of a glass rod, and immerse 
the glowing end of the wire in the borax. Use the wire in straight 
condition, without any loop. Now, hold the wire in the flame, 
observe the behavior of the borax, and explain [R 691. See 
Note 4, p. 1]. The bead must be small to avoid its drop- 
ping off. 
d. Bring the hot borax bead in contact with a minute particle 
of manganese dioxide [Notes 11 and 12], heat in the flame near 
the outer edge until the particle has dissolved, and observe the 
color of the bead when cold (?). If the bead is opaque, too 
much of the dioxide has been taken: melt the bead, throw it off, 
and start again. 
e. Cut off the gas supply until the flame is about 6 cm. in 
height. Close the air-holes until a luminous point appears 
at the apex of the inner cone, and hold the bead containing the 
manganese dioxide steadily in this luminous (reducing) portion. 
Before withdrawing the bead, lower it into the inner cone of 
unburnt gases to cool. Observe the color of the bead (?). 
/. Reheat the bead in the oxidizing part of the flame (?). 
4. Glass-Working [Blast-Lamp Table. Instructions, and 
Note 18, below]. 
* In this Outline the common, or popular names are often used 
intentionally. The systematic names must, in such cases, be found 
by the student [R]. §4] 
MANIPULATION 
5 
a. Cut a small piece off the wide soft glass tubing and make 
a test-tube out of it. 
b. Make a test-tube of hard (? [R 726]) glass. 
c. Connect two pieces of narrow glass tubing to make a longer 
piece. 
d. Make a T-tube by connecting two pieces of narrow glass 
tubing at right angles to each other. 
Note 18. - To cut narrow glass tubing make a slight, trans- 
verse scratch with the triangular file. Hold the tubing so that 
the points of the thumbs are together opposite to the scratch, and 
press forward with the thumbs so as to bend the tube away from 
this mark. Wide tubing may be cut by making a deep scratch 
completely round the tube and starting the crack by touching with 
the red-hot end of a glass rod. Other methods may be shown by 
the instructor. 
Always round off (fire-polish) the sharp edges of freshly cut 
tubes by softening in the Bunsen flame (why do the edges become 
rounded?). In the case of test-tubes, and other tubes of wide bore 
in which corks are to be inserted, the mouth must be strengthened 
and rendered fit for receiving the cork. To accomplish this, heat 
the edge in the flame and spread it slightly, but uniformly, by 
rotating in it a pointed piece of charcoal, or by turning outward 
the softened edge with the reverse end of a file. 
In making test-tubes and in connecting pieces of tubing, distend 
the softened parts by blowing immediately before allowing to cool, 
otherwise cracks are likely to appear. 
To bend glass tubing, never use the Bunsen flame (why? 
Note 3). Place a wing-top on the burner, and use the resulting 
flat, luminous flame of fish-tail form. Hold the tubing lengthwise 
in the flame, not across it (why?), turning the tube slowly round its 
axis to insure uniform heating. Keep the tube straight until it is 
soft enough to bend by its own weight. Finally, do not actually 
make the bend while the tube is in the flame, but after removal from 
it (why?). 
Fig. I 
Hold a piece of tubing in the Bunsen flame, without rotating the 
tube, and bend it while it is in the flame (?). Compare the bend 
with one made in the proper way (Fig. 1, left half) and account for 
the difference. 6 
MANIPULATION 
[§ 5 
5. Construction of a Wash-Bottle. Select a good cork which 
will fit the mouth of the largest flask and soften it by rolling 
under the foot upon the floor while pressure is cautiously ap- 
plied. Bore two parallel holes with the cork-borer, and smooth 
them by means of a rat-tail file [Note 19, below]. Bend two 
pieces of glass tubing as indicated in Fig. 
2 [Note 18], fire polish their edges and 
insert them in the openings in the cork. 
Make the nozzle by softening a piece of 
glass tubing in the Bunsen flame, drawing 
it to capillary dimensions after removal 
Fig. 2 Fig. 3 
from the flame (Fig. 3), cutting (6-8 cm. long), and fire- 
polishing. Connect the nozzle by means of a short piece of 
rubber tubing. Test the apparatus to see that it is air-tight 
[Note 20]. Finally, fill the flask with distilled water [Note 21]. 
Note 19. - The cork borer is usually made of brass, and the 
edge is easily turned. Form the habit of examining the edge and 
freshening it by cautious application of a triangular file [Instruc- 
tions. Note 6] every time it is to be used. Do not hold the cork 
against the table while boring, as the edge of the tool may be 
ruined. Hold the cork in the hand and bore from the narrow end 
with care, exactly parallel to the axis. If the cork and borer are 
rotated round their axes and the edge is fresh, very little force will 
be required. Clear the core of cork out of the cork-borer, after use, 
by means of the iron rod. The borer is purposely chosen so as to be 
smaller than the tubing. Its use thus permits the enlarging and 
smoothing of the hole with the rat-tail file until a perfectly fitting 
bore has been made. 
Note 20. - Before use, every piece of closed apparatus employed 
in this and all succeeding experiments must be tested for air- 
tightness, and rendered perfectly air-tight. In this instance place 
in the flask enough water to cover the lower end of the longer tube, 
transfer the rubber connection to the shorter glass tube, and close 
it with a clamp. Now, blow through the longer tube so that a 
few bubbles of air pass into the flask. If the apparatus is air- §6] 
MANIPULATION 
7 
tight the water will rise in this tube when the mouth is withdrawn 
and will remain in an elevated position. If the water gradually 
sinks to its former level, the apparatus is not air-tight. Exami- 
nation of the holes in the cork may show defects, which can be 
remedied only by boring a fresh cork more carefully. If the cork 
itself contains pores, these may often be closed by thorough wetting. 
Do not on any account employ paraffin or sealing-wax to patch 
defective places in a cork; use a fresh one. 
Note 21. - Distilled, water is to be used for making solutions 
and for rinsing glassware (why?). Common water is to be used 
for all other purposes. 
6. Use of the Simple Balance [Instructions. Quant.]. By 
turning the screw attachment in front of balance case, release 
the beam and pans, allowing the beam to swing. Observe the 
excursions made by the pointer. Divide by two the total divi- 
sions covered by the pointer in one full swing, and count off 
from either end of the swing the divisions which this number 
designates, thus finding the position of the true zero point. The 
beam must swing freely during the observation: the zero is never 
to be read with the beam at rest. 
This observed zero point may lie a little to the right or to the 
left of the marked zero. Note down its distance, in scale divi- 
sions, from the marked zero. If it lies to the right prefix to 
the number of divisions the minus (-) sign; if to the left the 
plus (+) sign. The zero of any one balance changes, and must 
be redetermined every time a weighing is made. 
Place a 10 g. weight in each pan [Note 22, below], and deter- 
mine the zero as before. Add the 0.01 g. weight to the right- 
hand pan, and find the reading about which the pointer now 
oscillates. The difference in reading between this point and the 
last determined zero point gives the deflection due to the 0.01 g. 
weight. It may be used for estimating weights less than 0.01 g. 
Thus, suppose the 0.01 g. weight causes a deflection of 5 divisions 
to the left (+5). When some body is being weighed, if the 
deflection is +1, then | of the 0.01 g. or 0.002 g., must be added 
to the sum of the weights. 
Note 22. - Great care must be taken in the use of the balance 
and weights. The pans of the former must be let down upon 
their supports when not in use and every time weights or other 
objects are to be added or removed. All objects to be placed upon 
the pans must previously be carefully cleaned and dried. Solids 8 
MANIPULATION 
[§ 7 
are placed upon a watch-glass or upon a piece of glazed paper, and 
never directly upon the pans. The weights must be lifted from 
their case by means of forceps, never 
by the fingers. They are usually placed 
on the right-hand pan, the objects to 
be weighed on the left. 
Note 23. - In reckoning results, 
count first by the places vacant in 
the box, and check by counting the 
weights themselves. This will enable 
you to avoid the commonest error in 
weighing, namely, miscounting the 
weights. Finally record the weights in 
the note-book, or laboratory outline, 
and never upon loose sheets of paper, 
as loss of the latter will necessitate a 
repetition of the entire experiment. 
7. Measuring Vessels [Quant.]. 
a. Fit a burette (Fig. 4) with a 
short piece of rubber tubing and glass 
nozzle (see 5). The withdrawal of liquid from the burette is 
regulated by a pinch clamp upon this rubber connection, or 
by placing a small piece of glass rod (with fire-polished edges) 
in the middle of the rubber tubing to choke the bore. In this 
latter case, pinching the tubing surrounding the glass rod will 
permit the liquid to flow at any desired rate from the nozzle. 
b. Support the burette upon a ring-stand by means of a clamp. 
Now fill the burette with distilled water, drawing off a portion to 
insure the complete removal of air from the rubber tubing and 
nozzle. The last bubble of air may be removed 
by turning the nozzle upward while the water is 
allowed to flow. Read the height of water by ob- 
serving the lower side of the meniscus (Fig. 5) and 
estimate to tenths of a division. 
Clean and dry a small beaker carefully and weigh 
it [Quant.]. Allow 10-20 c.c. of the distilled water 
to run from the burette into the beaker, read the 
new level of the water, and ascertain the volume taken by sub- 
tracting the readings. Weigh the beaker again and ascertain 
the weight of the water by subtraction. Calculate from your 
figures the weight of 1 c.c. of water. Keep the beaker and 
contents for use in c. 
Fig- 4 
Fig. 5 §8] 
MANIPULATION 
9 
c. Place some distilled water in the graduated cylinder and 
read its volume. Pour about 10 c.c. of this water into the 
beaker (already partly filled with water), read the volume of 
the remainder, and find by subtraction the volume poured out. 
Now weigh the beaker once more and find the weight of this 
water by subtracting the previous weight. Calculate the weight 
of 1 c.c. of water. 
Is measuring volume by burette or by cylinder more accurate, 
and why? 
d. Measure by means of the cylinder, roughly, the volumes of 
water your flasks and beakers hold, and record the figures. Fill 
the vessels to a convenient height for use, and not to the brim. 
8. Physical Properties, Attributes, and Conditions. Make 
a list of the physical properties [R 40] of water, so far as you 
have observed them (?). 
Which attributes [R 40] were employed in 7 b and c? 
What conditions [R 41] (temperatures and pressures) existed 
while 7 a and b were performed? CHAPTER II. 
CHARACTERISTICS OF CHEMICAL PHENOMENA. 
9. Qualitative Study of Chemical Phenomena. 
a. Rub a pinch (about 0.5 g.) of powdered roll sulphur with 
a very small globule of mercury (use the dropper) in a mor- 
tar (?). When the mass has been intimately ground together 
for about five or ten minutes and no particles of mercury are 
longer observable, place it in a dry test-tube and add about 
3 c.c. of carbon disulphide [CARE! Keep away from flames], a 
solvent for the free sulphur. Shake well (do not apply heat) 
and then pour off the clear solution into the sink [Hood. Note 
25, below]. Repeat, shaking well and pouring away the clear 
liquid. Continue this operation until a sample of the decanted 
liquid fails to give any sulphur by spontaneous evaporation 
upon a watch-glass. What is the product remaining in the tube 
[R 780]? By means of a few c.c. of carbon disulphide wash this 
product out upon a filter paper [Note 24, below] and allow it to 
dry. To show the composition of this substance place it in a 
small, clean, dry test-tube and heat strongly over a flame. What 
odor is noticed at the mouth of the tube? What product is 
found to sublime upon the walls of the test-tube? Rub the 
sublimate with a glass rod (?). What characteristics of chemi- 
cal change have you noticed in the above experiment? 
The mortar may be cleaned by placing in it a few drops each 
of hydrochloric acid and of nitric acid. 
Note 24. - Cut from a sheet of filter paper a piece 7 cm. (3 inches) 
square. Fold the square twice in directions at right angles to one 
another, so as to obtain a square of one-fourth the previous area. 
Cut off the loose corners with scissors so that a quadrant is formed. 
Open the folded paper so that a cone is produced (Fig. 6), and 
place the cone in a dry glass funnel. Smaller or larger pieces of 
paper are taken according to the amount of the precipitate or 
of the liquid to be filtered, the smallest size that will serve the 
purpose being preferred. The funnel must be chosen so that the 
filter paper, after being trimmed and placed in position, does not 
quite reach the edge, much less project above it. While in use, 
10 §91 
CHEMICAL PHENOMENA 
11 
the funnel is placed in a ring on the stand, and is not to be held 
in the hand. 
Note 25. - Pour away all ill-smelling substances, like carbon 
disulphide, in the sink in the hood and not in the ordinary sinks 
or jars. 
b. Make separate lists of the physical properties of mercury, 
of sulphur, and of mercuric sulphide, as you have observed them 
(?). Are mercury and sulphur the components, or the con- 
stituents of mercuric sulphide? 
c. Gunpowder is made from saltpeter (potassium nitrate), 
roll sulphur, and charcoal. Take specimens of these three sub- 
stances, and examine them with respect to properties which can 
be used for recognition and separation [R 40, 42], such as ap- 
pearance and solubility in various solvents. Try the solubility 
Fig. 6 
Fig. 7 * 
of each in distilled water and in carbon disulphide, using in the 
latter case thoroughly dried (why ?) test-tubes [Notes 25 and 26]. 
Do not judge of solubility by the eye, but filter the mixture 
[Note 24], catch a few drops of the liquid on a watch-glass, 
evaporate, and see whether there is any greater stain on the glass 
than the pure solvent would itself have left. The taste (?) of 
the saltpeter is a characteristic property. 
Now place about 1 g. of gunpowder in a large test-tube and 
add 5-10 c.c. of water. Shake well (after closing the test-tube 
with the thumb), warm gently, and filter [Note 24]. Evaporate 12 
CHEMICAL PHENOMENA 
[§ 10 
the filtrate upon a water bath, or over a beaker of boiling water 
(Fig. 7). Describe and name the residue (?). Dry (why?) the 
filter paper and its black contents over a radiator or in a drying 
oven. Shake the dried product with cold carbon disulphide in 
a dry [Note 26] test-tube, filter, and allow the filtrate to evapo- 
rate [Hood] spontaneously (?). What remains upon the paper? 
Did any chemical change occur during the manufacture of gun- 
powder? Are the three substances components or constituents 
of gunpowder? Is the latter a mixture or a compound? 
Why are the ingredients of gunpowder pulverized so finely and 
mixed so intimately? 
Note 26. - To dry test-tubes or flasks quickly after recent 
washing, warm them slightly in the Bunsen flame, connect with 
the air supply of a blast-lamp a piece of glass tubing long enough 
to reach to the bottom of the vessel, and allow a gentle stream of 
air to flow through the tube and vessel. 
10. Law of Definite Proportions * [Quant. R 54]. Obtain two 
pieces of pure lead of different sizes, about 0.5 g. and 0.6 g., 
respectively. Clean and dry two evaporating dishes, taking 
care to remove any paper labels which may be attached to them, 
and weigh each with care [Quant., balance]. Place one piece of 
the lead in each and weigh again. Record the results in the form 
shown below. The difference will give the exact weight of the 
lead. Be careful in your notes, and in handling, to distinguish 
the dishes from one another. 
Dilute 7 c.c. of pure, concentrated nitric acid with 14 c.c. of 
water in the graduated cylinder and add to the lead in each 
dish 10 c.c. of the diluted (1:2) nitric acid. Cover each dish 
with a watch-glass, convex side downward, and set upon the 
water bath. An extra Bunsen burner [Storeroom] and two 
beakers containing water may be used as baths, as in Fig. 7 
[Hood]. A match inserted between the dish and the beaker 
permits escape of the steam and prevents the possible upsetting 
of the dish by the vapor. When the action is over, and the lead 
* Before beginning, always endeavor to ascertain the object of each 
experiment. By this means confused work and much waste of time 
will often be avoided, and significant facts to be observed and recorded 
will not escape notice. Consider, first, carefully the title, as it will 
usually indicate the object of the exercise. If the title is not at once 
fully understood, look up the topic in a reference book before going 
further. §101 
CHEMICAL PHENOMENA 
13 
has entirely disappeared, rinse the lower surface of each watch- 
glass into the dish by means of a little water from the wash- 
bottle. Then add to the contents of each 5 c.c. of pure dilute 
hydrochloric acid. This causes the precipitation of a compound 
of lead and chlorine whose weight is next to be determined. To 
accomplish this, the water and other substances present (except 
the lead chloride) being all volatile, the mixture is dried by evapo- 
ration on a water bath. When the contents of the dishes are 
dry, moisten the contents of each with 2 c.c. of pure, concen- 
trated hydrochloric acid and dry once more. Now transfer 
the dishes, one at a time to the clay triangle supported on the 
ring-stand, and heat the whole residue cautiously with a small 
Bunsen flame. Watch it narrowly and do not allow any of it to 
melt. When the dishes are cold, weigh each again with care. 
The increase in weight over the previous value in each case 
gives the weight of chlorine which has combined with the known 
weight of lead. 
Dish No. 1. Dish No. 2. 
Wt. of dish with lead (silver) 
Wt. of dish, empty 
Wt. of lead (silver) 
Wt. of dish with lead (silver) chloride 
Wt. of dish with lead (silver) 
Wt. of chlorine 
Wt. of lead (silver) 
Wt. of chlorine 
Wt. of lead (silver) chloride 
I 
Per cent lead (silver) (x) 
Per cent chlorine (x') 
Calculate from each of the two sets of data the percentage of 
lead (x) and of chlorine (x') in lead chloride: 
Wt. of lead used : Wt. of lead chloride :: x : 100. 
Wt. of chlorine found : Wt. of lead chloride :: x': 100. 
Compare the results of the two measurements and interpret (?). 14 
CHEMICAL PHENOMENA 
[§ 11 
11. Law of Definite Proportions * [Quant. R 54]. 
a. To secure almost ideal results, two pieces of pure silver 
foil of about 0.5 g. and 0.6 g. should be substituted for the lead 
in 10. Record the weights as shown above. 
Dilute 5 c.c. of concentrated nitric acid with 5 c.c. of distilled 
water in the graduated cylinder and add to the silver in each 
dish 5 c.c. of the diluted (1:1) acid. When the action is over, 
and the cover-glasses have been rinsed, as in 10, add 2 c.c. of 
pure dilute hydrochloric acid to the contents of each dish. 
This causes precipitation of a compound of silver and chlorine. 
Evaporate the liquids to dryness [Hood] and heat the residues at 
once until signs of melting are seen. Weigh each dish. The 
increase in weight over the previous value in each case gives the 
amount of chlorine which has combined with the known weight of 
silver. 
Calculate from each of the two sets of data the percentages 
of silver (x) and of chlorine (z') in silver chloride: 
Wt. of silver used : Wt. of silver chloride :: x : 100. 
Wt. of chlorine found : Wt. of silver chloride :: x' : 100. 
Compare the results of the two measurements and interpret (?). 
Before cleaning the dishes, transfer the silver chloride to the 
bottle for silver waste. 
b. Clean and dry two evaporating dishes, taking care to 
remove paper labels which may be pasted upon them. Weigh 
each dish [Quant., balance]. Place in each some sodium- 
hydrogen carbonate, in the one about 1 g. and in the other about 
2 g., and weigh again. Treat both alike, as follows: Dissolve 
the solid in pure dilute hydrochloric acid [R 117], adding little 
by little and covering with a watch-glass between successive 
additions to avoid loss by spirting. When the solid has wholly 
dissolved, wash the watch-glass over the dish, and evaporate 
[Hood] the contents of the latter on the water bath, or on a 
beaker of boiling water (Fig. 7). (Avoid loss of time by bor- 
rowing a second bunsen burner and gas tubing temporarily 
from the storeroom.) Allow the dishes to cool, and weigh. To 
make sure that the drying was complete, heat once more for 
half an hour and weigh again. This precaution is taken in all 
experiments of this kind. The product is common salt. 
* See footnote, p. 12. § 11] 
CHEMICAL PHENOMENA 
15 
Dish No. 1. Dish No. 2. 
Wt. of dish + sod. bicarb. 
Wt. of dish (empty) 
Wt. of sod. bicarb. 
Wt. of dish + salt 
Wt. of dish (empty) 
Wt. of salt. 
Ratio (z) 
Calculate the proportion of carbonate taken to salt produced: 
Wt. of carbonate : Wt. of salt :: 1 : x. 
Compare the two values of x found from the two differing quan- 
tities of the carbonate and interpret (?). 
What physical property of hydrochloric acid permits use of an 
excess of the acid without damage to the result? What form 
of statement of the law is verified directly by this experiment? CHAPTER III. 
OXYGEN. 
12. Sources (p. 12, footnote). Heat small quantities of 
barium peroxide, lead dioxide, potassium nitrate, silicon dioxide 
(sand), and manganese dioxide (dry this before use by heating it 
for a few minutes in a porcelain crucible) separately in a hard 
glass test-tube [Note 27]. Observe whether any gas is given 
off, and apply the test of the glowing splinter of wood [Note 28]. 
If the Bunsen flame proves inadequate, try the blast-lamp. 
Note any changes in appearance during the heating and de- 
scribe the residues [Note 29]. Clean the test-tube carefully 
with hot nitric acid [CARE] and dry it [Note 26, p. 12] after 
each experiment. 
Note 27. - Use the clamp and ring-stand to support the tube, 
or grasp it by means of a strip of folded filter paper (Fig. 8). In 
either case it must be kept in a horizontal position, other- 
wise condensed moisture may run down and cause it to 
crack. 
Note 28. - Use a long splinter of pine wood bearing 
a spark at one end (why not an ordinary match?). 
Such a splinter is at once kindled by oxygen. 
Note 29. - Beginning with this chapter include in 
your notes equations for all the chemical changes you 
observe. When no change is observed, do not attempt 
to give an equation until otherwise instructed (Chap. IX). In the 
present experiments, the formulae of the materials used will have to 
be sought in the text-book. The formulae of the products will also 
be sought in the book after the physical properties of the product 
and the evolution or non-evolution of oxygen have been noted and 
an indication of what to seek for has thus been obtained. For 
other information in regard to the note-book, see the "General 
Instructions," Notes 1-5, p. 1. 
13. Catalytic Action. 
a. Place in a test-tube a little potassium chlorate, fix the 
tube in a vertical position by means of a burette clamp attached 
to the ring-stand, and melt the substance at the lowest tem- 
Fig. 8 
16 §14] 
OXYGEN 
17 
perature at which this is possible (patience!). Note whether 
there is evidence of the evolution of oxygen. Now throw into 
the molten material a pinch of powdered manganese dioxide (?) 
[Note 2, p. 1], keeping the face out of the path of anything 
which may accidentally be projected from the tube. Interpret 
[R 97]. 
b. Devise a way of showing that the manganese dioxide, 
used as in a, remains unchanged after the action, and that it 
is the potassium chlorate that loses its oxygen, and try it (?). 
Consult the instructor in regard to the details of your plan 
before executing it. 
14. Preparation. Mix on paper about 5 g. of potassium 
chlorate and 3 g. of powdered, dried (see 12) manganese dioxide. 
Fig- 9 
Place the mixture in a hard glass test-tube provided with a one- 
hole cork and delivery tube (Fig. 9. The deeply shaded parts 
are rubber). Test the apparatus to see that it is air-tight [Note 
30, below]. 
Clamp the test-tube on the ring-stand and heat carefully, 
so as not to cause too violent an evolution of oxygen. Collect 
four bottles of the gas over water in a pneumatic trough, taking 18 
OXYGEN 
[§ 17 
care to remove the delivery tube from the water as soon as the 
bottles are full of oxygen (why?). The test-tube may be cleaned 
by allowing it to soak in water. 
Note 30. - To test for air-tightness, place the end of the deliv- 
ery tube in the mouth, withdraw some of the air by suction, and 
note whether or not the tongue will adhere to the end of the tube. 
If it will not, there is a leakage which must be remedied. 
15. Properties [Note 5, p. 1]. 
a. Place a very small amount of sulphur in a deflagrating 
spoon, ignite it, and then lower into a bottle of oxygen (?) [Note 
2, p. 1]. 
Remove the spoon, and note the odor (?) of the gas in the 
bottle. Then add a little water to the jar, close the mouth 
with the hand and shake (?). Test the water with blue litmus 
paper or solution [R 117, 392]. Make lists of such physical 
[R 40] and chemical properties of the product as you have 
observed (?). 
b. Place a little red phosphorus in the spoon, ignite it, and 
lower into the second bottle (?). 
Proceed as in a. Test with the blue litmus [R 117]. Why 
does the product form a smoke, instead of remaining in the spoon? 
(If yellow phosphorus is used, it must always be cut under 
water and handled with forceps. Great care must be taken 
not to touch it with the hand, as it catches fire easily, and causes 
very severe burns. Red phosphorus is safer, and should be 
employed if available.) 
c. Lower a splinter of glowing charcoal into the third bottle 
holding it in the tongs or wrapping the end of a piece of copper 
wire round it (?). 
Proceed as in a (use no litmus), and cover the mouth of the 
bottle with a glass plate. Add some limewater (calcium hy- 
droxide) and shake again [R 576] (?). 
16. Slow Oxidation of Metals. Devise a way of showing 
that air loses a part of its substance (not, e.g., that the iron 
gets heavier, but that the air diminishes in amount) when moist 
iron powder rusts, and try it. Submit your arrangement to 
the instructor for criticism before using it. 
17. Weight of a Liter of Oxygen [Quant.] (p. 12, footnote). 
a. Powder some potassium chlorate, and dry it on a watch- 
glass on the radiator, or high above a small Bunsen flame, or § 17] 
OXYGEN 
19 
in a drying oven. Construct an aspirator (Fig. 10), using the 
1-liter bottle, and connect it with a hard glass test-tube. Fit 
a nozzle to the rubber tube and slip a pinch clamp over the out- 
let tube (syphon) in readiness for closing, at a later stage, the 
rubber tube that connects the two glass tubes. Having inserted 
the stopper tightly and connected the test-tube, test the appara- 
tus to see that all the joints are air-tight [Instructions: Place 
Fig. zo 
some water in the bottle, blow a few bubbles of air into the 
apparatus through the syphon, and observe whether the water 
remains permanently elevated in the vertical tube. Absolute 
certainty that the apparatus is air-tight must be reached before 
proceeding further]. 
Carefully weigh the hard glass test-tube, then place in it 
between 1 g. and 2 g. of potassium chlorate and weigh again. 
Record the results as shown below. More than 2 g. is not needed, 
less than 1 g. will not be sufficient. Subtraction gives the exact 
weight that has been employed. Fill the bottle almost, but not 
quite, to the shoulder (not the neck) with tap water. After 
reattaching the test-tube, make sure that the apparatus is once 
more air-tight, by repeating the above-described test. Next 
fill the syphon and nozzle completely with water by blowing 
sharply through the latter, and close the clamp. Allow the 
nozzle to touch the bottom of a beaker (400 c.c.) containing 
some water. Now open the clamp and raise the beaker till the 
levels of the water in this and the bottle are the same, and the 
gaseous pressure therefore alike in both. Close the clamp again, 
empty the beaker and replace it in position. 20 
OXYGEN 
[§ 17 
Wt. of tube with chlorate g. 
Wt. of tube with residue g. 
Wt. of oxygen g. 
Vol. of water driven over c.c. 
Temp, in lab ° 
Temp, near barometer 
Barometric height mm. 
Correction mm. 
Barometer (corr.) mm. 
Aqueous tension at temp, of lab mm. 
Partial press, of ox mm. 
Open the clamp once more and decompose the compound 
slowly by heating, catching in the beaker the water driven 
over by the gas. At least 250 c.c. of water should be driven over. 
During the earlier stages a smoke, consisting of solid particles, 
will arise. This must on no account be driven into the con- 
necting tube, as all the solid must remain in the test-tube to be 
weighed (why?). Suspend the heating as often as may be 
necessary to let this smoke settle. During such intervals of 
waiting, see that the nozzle is constantly immersed in the water 
that has already passed over (why?). Stop heating if the 
tube shows signs of softening [Note 31, below], or when the 
decomposition is complete. For the purpose of this experiment 
(see 17 6) it is not necessary that the action should be carried to 
completion. If, when the heating is stopped, the nozzle is not 
under water, raise the beaker until it is well covered. Allow the 
whole apparatus to stand until it has reached the temperature 
of the air. Some water will return to the bottle by the syphon 
during the cooling. As this transference of water is essential to 
the success of the experiment, at no stage should air be allowed 
to enter the syphon through the nozzle. Equalize the levels of 
the water in both vessels by raising or lowering the beaker, and 
then close the clamp. 
Measure the volume of water in the beaker by means of the 
graduated cylinder (?). This represents the number of c.c. of 
water displaced, and hence of oxygen evolved in the operation 
(what of the air originally in the apparatus?). Weigh the test- 
tube once more with care [Balance]. Observe at the same time; §17] 
OXYGEN 
21 
the temperature in the laboratory to learn the temperature of the 
oxygen (?), and read the barometer [Note 32, below] to learn 
the pressure of the air and therefore of the oxygen (?). 
Subtract the aqueous tension (Appendix II) [R 145] at the ob- 
served laboratory temperature from the barometric reading 
(corr.) to get the true (partial) pressure of oxygen in the bottle. 
Reduce the volume by rule to 0° and 760 mm. [R 110]. The 
weight of this volume of oxygen is obtained by subtracting the 
weight of the residue in the test-tube from the weight of the 
potassium chlorate originally taken. Calculate by proportion 
from the data obtained the weight of 1 liter of oxygen (x): 
Vol. of ox. found : Wt. of ox. found :: 1000 c.c. : x. 
Calculate also the volume occupied by 32 g. of oxygen. To 
what class of gases would the use of the aspirator be confined 
for purposes like the above? 
Note 31. - To avoid softening of the glass, through overheating, 
watch the color of the Bunsen flame. The blue flame is tinged 
with a yellow color (caused by compounds of sodium in the glass) 
where the flame encounters the overheated part of the tube. 
Note 32. - When the barometer is read, the height must be 
"corrected" to that of a column of mercury at 0° (Appendix I). 
b. Detach the hard glass test-tube from 17 a and drive off 
the last traces of oxygen by heating strongly every portion of 
the tube to which any of the residue adheres. Allow it to cool 
and weigh. Obtain the weight both of the residue (potassium 
chloride) and of the total oxygen, by difference. 
Wt. of tube with chlorate 
Wt. of tube with chloride 
Wt. of oxygen 
Wt. of tube with chloride 
Wt. of tube empty 
Wt. of chloride 
Assuming the formula of the chloride to be KC1, that of the 
chlorate is KCIO^. The formula weight of KC1 being 39.1 + 
35.46 = 74.56, find the formula weight of Ox by the proportion: 
Wt. of KC1 found : Wt. of oxygen found : : 74.56 : y, 22 
OXYGEN 
[§ 17 
where y = Ox. This will be a multiple of 16 by a whole number 
(why?) if the measurement has been carried out successfully. 
What formula do you find for potassium chlorate? Write 
the equation for the decomposition of the chlorate (?), CHAPTER IV. 
HYDROGEN. 
18. Interaction of Metals and Acids. 
a. Place a few small pieces of each of the metals, tin (gran- 
ulated), copper, iron (filings), zinc (gran.), lead (gran.), alumin- 
ium (turnings), and magnesium (wire) in separate test-tubes. 
Place in the measuring cyUnder 20 c.c. of pure concentrated 
hydrochloric acid [R 117] and add an equal volume of water. 
Add 5 c.c. of the mixture to the contents of each test-tube (?). 
Observe each case critically [Note 33, below] and record the 
results [Note 29, p. 16], noting the order of the metals in respect 
to activity. Action on the aluminium will not occur until the 
tarnish has been removed from the surface by the acid. If no 
action occurs in the cold, try the effect of gentle heating. If 
heating seems to produce gas, remember that it may be hydrogen 
chloride (why?) or steam and not hydrogen. The presence of 
hydrogen may be inferred from continued effervescence when 
heat is not being furnished, and may be proved by the slight 
explosion which follows when a light is brought to the mouth 
of the tube. But hydrogen will not burn when mixed with much 
air or with other vaporous substances (why?). After the action 
has ceased, filter any one of the solutions and evaporate [Hood] 
it to dryness on the sand bath (?). 
Can you give any grounds for the belief that the hydrogen 
comes from the acid and not from the metal or the water? 
Which metals, not used above, will displace hydrogen from 
dilute acids [R 129]? In what ways, if at all, does the order of 
activity you have observed differ from that accepted by chemists? 
In making the equations for these actions all that is needed, 
beyond the information given above and acquired by observation, 
is to find the formulae of the products. These are not here to be 
sought by measurement, but in the text-book [R]. 
b. Ascertain the influence of the physical state of the metal 
on its apparent activity by adding some zinc dust to the same 
acid. 
c. Place one small piece of pure zinc into each of two test- 
23 24 
HYDROGEN 
[§ 20 
tubes and add diluted sulphuric acid to both tubes. If little or 
no action takes place in the cold, try upon one tube the effect of 
heating (?). Try the effect of putting a platinum wire in contact 
with the zinc in the second tube (?). Notice where the hydrogen 
appears to come from, and explain [R 29]. Withdraw the 
platinum wire, add one drop of cupric sulphate solution, and 
shake until the blue color is removed from the solution (?). Is 
the zinc still silvery? What is the substance upon the zinc 
[R 403], and what effect does it produce upon the apparent 
activity of this metal? Explain (?). 
d. Now compare (?) the behavior of concentrated sulphuric 
acid with that of the diluted acid used in 18 c, by placing some 
zinc (gran.) in a test-tube and adding enough of the concentrated 
acid to barely cover the metal (why not more?). After noticing 
the effect in the cold (?), apply heat (?). Odor (?). What 
products are formed [Note 33]? 
e. Try the interaction of acetic acid with zinc (gran.) or iron 
(filings). Apply heat, if necessary. 
Note 33. - In observing an interaction a chemist first mixes 
the substances thoroughly by shaking. If nothing occurs, he then 
heats. If his eye detects evidence of the production of a gas or 
vapor, he finally smells the contents of the tube. Apply these 
three methods of observation to d before drawing any conclusion. 
19. Other Methods of Obtaining Hydrogen. 
a. Describe the result of throwing pieces of sodium and of 
potassium into water, as you recall having seen it [Classroom]. 
Write the equations for these two actions (?). What other 
metals displace hydrogen from water [R 129]? 
b. Fit a test-tube with a one-hole cork and delivery tube 
(Fig. 9). Pulverize about 2 g. of sodium hydroxide, mix it 
intimately in the mortar with about 3 g. of zinc dust, and place 
the mixture in the test-tube. Insert the cork and delivery 
tube, test the apparatus for air-tightness (Note 30, p. 18), and 
clamp the tube in a horizontal position (why?). Heat the mixture 
and collect the gas (?) over water (Fig. 9) in a test-tube. If 
the tube should crack [caution !] cease heating at once. To 
learn whether the gas is combustible, carry the test-tube, when 
full of the gas, mouth downward, to a flame (?). 
20. Preparation of Hydrogen [Same apparatus is used for 21 
and 22]. Fit a 250 c.c. flask with a safety tube and exit tube §21] 
HYDROGEN 
25 
(Fig. 11), and test for air-tightness. Place in the flask some com- 
mercial, granulated zinc, close the apparatus, and attach to the 
L-shaped exit tube, by means of a short piece of rubber tubing, 
a longer glass delivery tube. Now pour 30-40 c.c. of dilute hy- 
drochloric acid through the safety tube. 
Test the issuing gas until it is found free 
from air [Instructions: The gas must not be 
ignited at once or the apparatus will be 
blown up (whence comes the air mixed with 
the hydrogen?). Collect samples of the gas 
from time to time by raising the delivery 
tube and inserting it to the upper part 
(why?) of a test-tube held in an inverted 
position. Close the mouth of the test-tube 
with the thumb, and bring the mouth of 
the tube (still inverted) to a distant flame. 
When the gas contained in the test-tube, 
after the first explosion of the part nearest 
to the mouth, burns quietly, the gas is free from air. Call an 
instructor to inspect the test]. Keep the apparatus in operation 
for use in 21 and 22. 
21. Properties of Hydrogen. 
a. By collection over water in the pneumatic trough, fill a 
test-tube with hydrogen. Using this, and a similar test-tube 
filled with air, show by an experiment that hydrogen is lighter 
than air (?). 
Fill another test-tube with hydrogen and apply it closely, 
mouth downward, to a test-tube of air, mouth upward. Allow 
the tubes to remain in this position for three minutes, then 
bring first the lower and then the upper tube quickly to a 
flame (?). What fact about diffusion does the result illustrate? 
b. Fill another test-tube with hydrogen, as in a, and, holding 
it mouth downward, insert into the tube a burning splinter. 
Does the splinter continue to bum? Explain. 
c. Remove the glass delivery tube, and connect a glass nozzle 
with the exit tube of the generating flask. Press the mouth of 
the nozzle close against the side of a cold, dry beaker. If 
moisture is deposited (what is its source?), fill a U-tube with 
calcium chloride [R 123] and connect it between the exit tube 
and the nozzle. Does the gas now deposit moisture upon a 
beaker? If not, ascertain that the issuing gas is not explosive 
Fig. n 26 
HYDROGEN 
[§22 
(see test m 20), and set fire to it. What is the color of the name? 
Does the color change, and, if so, why? Hold a cold, dry, 
inverted beaker over the flame. What is deposited on the 
beaker? Why did we use dried hydrogen for this experiment? 
Keep the apparatus in operation for 22, unless a Kipp's appa- 
ratus is available or hydrogen is furnished in the laboratory. 
Turn off the gas supplying the Bunsen burner, remove the 
burner and push a glass nozzle tightly into the end of the gas 
tubing. Turn on a gentle stream of illuminating gas and set 
fire to it. Hold a cold, dry beaker over this flame (?). What 
inference in regard to illuminating-gas do you draw? 
22. Reduction by Means of Hydrogen [Two students work- 
ing together]. Fit a hard glass tube, 25-30 cm. long and open 
at both ends, with perforated corks 
and short glass tubes (Fig. 12). 
Support it on the ring-stand by 
means of a clamp grasping it close 
to one end. Dry 1-2 g. of ferric 
oxide by heating in a porcelain 
crucible. Put the oxide into the 
porcelain boat and place the latter 
in the hard glass tube near the end 
remote from the clamp (why?), but 
not so near that the subsequent 
heating will char the cork. Insert 
the corks with their tubes. Con- 
nect the tube nearest to the boat with a Kipp's apparatus and 
drying bottle (Fig. 18) delivering dry hydrogen, or with the 
laboratory supply of the gas, or with the apparatus furnishing 
dry hydrogen used in 20. 
Test the issuing gas to see that it is not explosive (see 20) 
and repeat the test every time the apparatus is opened. Now 
heat the boat and contents, at first gently by waving the flame 
under the tube, and later strongly until the material is red-hot 
(what temperature is used [R 94]?). Observe the effect upon 
the ferric oxide [R 896] (?). Does anything condense in the 
cooler end of the tube? 
What is the action of steam upon heated iron [R 116]? How 
do you reconcile this fact with that observed above? 
Repeat the above experiment, using freshly heated aluminium 
oxide in place of ferric oxide, and otherwise following the direc- 
Fig. 12 §22] 
HYDROGEN 
27 
tions exactly (?). If no effect is noticed after an oxide has been 
at a red heat for three minutes, absence of action may be inferred. 
How do you account for the result obtained with aluminium 
oxide? Which oxides are reducible by hydrogen [R 130]? CHAPTER V. 
WATER AND SOLUTION. 
23. Purity of Water. Place a few drops of distilled water 
on a clean watch-glass (not an evaporating-dish. Why?), and 
evaporate on the water bath. Do the same with ordinary water. 
Observe whether any stains remain on the glasses (?). What 
class of impurities would leave no trace of their presence in 
this test? 
24. Union with Oxides. Place a pinch of cupric oxide in a 
test-tube and wash it by shaking with a little distilled water 
and pouring off the liquid. Add more water and shake again. 
Test this latter solution with litmus paper (?). At the same 
time test a sample of the water with litmus paper and compare 
the tints. Repeat with barium oxide (?). 
Recall the behavior of acid-forming oxides examined in 15. 
Some oxides do not interact readily with water (which?). These 
oxides which do interact may be divided, according to the 
natures of the products they give, into two classes. What are 
those classes, and which oxides belong to each? What are the 
two classes of elements whose oxides belong to the two groups, 
respectively [R 150]? 
25. Hydrates. 
a. Heat some blue vitriol (p. 4, footnote) gently in a porcelain 
crucible (?). Allow a very small portion of the white powder 
to stand exposed to the air on a watch-glass (?). Dissolve the 
remainder by boiling with the minimum amount of water 
required to dissolve it, and set the solution aside (?). What 
chemical actions have taken place in these three operations? 
b. [Quant.] Place small quantities (about 1 g.) of Glauber's 
salt and of blue vitriol in two porcelain dishes and ascertain 
the gross weight in each case. Allow the dishes and contents 
to remain for 24 hours or more and weigh again (?). Interpret 
the results [R 151]. 
c. Pulverize small quantities of barium chloride, potassium 
nitrate, magnesium sulphate, and potassium dichromate sepa- 
rately in the mortar. Warm them, separately, in dry test-tubes 
28 §27] 
WATER AND SOLUTION 
29 
and notice whether they undergo any change [R]. Mere 
melting does not show that the substance is a hydrate. 
Are all crystalline substances hydrates? Classify the sub- 
stances you have examined into two groups with reference to 
this property. 
d. Take in a test-tube about 5 c.c. of commercial, concen- 
trated sulphuric acid, place in it a crystal of blue vitriol and 
let the materials stand for an hour, or more (?) [R 438]. Now 
heat the contents of the tube to the boiling-point of the acid, 
holding the test-tube in a test-tube holder, keeping it far from 
the clothing, and taking care that none of the contents spirt 
out upon the hands or face [caution: Sulphuric acid burns 
are very painful. Note 16, p. 2], After the contents of the 
tube have settled, pour off the clear liquid into another tube. 
On the following day, examine the little, shining particles on 
the sides of the tube. What is their color, and condition? Of 
what are they composed [R 745]? 
Are the compounds (such as cupric sulphate) which, in presence 
of water, yield crystalline hydrates, amorphous or crystalline 
in its absence? What is the true significance of the crystalline 
condition [R 154]? 
e. Take a clean match and, after dipping it in a solution of 
cobalt chloride, write upon a piece of white paper. After the 
writing is dry, warm the paper gently by waving it above a 
Bunsen flame (?). Now, breathe repeatedly upon the writing (?). 
Write equations for the actions that have occurred [R 900]. 
26. Formula of a Hydrate [Quant.]. Put about 1 g. of 
crystals of gypsum in a weighed porcelain crucible and weigh 
again. Place the crucible on the clay triangle, heat to redness 
until no further loss in weight occurs, and determine by difference 
the loss in weight (water) and the weight of the calcium sulphate 
remaining. 
The formula of gypsum must be CaSO^xELO. Assuming 
the formula-weights of calcium sulphate (CaSCh = 136) and 
of water (H2O = 18), calculate from your data the value of x: 
Wt. of calcium sulphate : Wt. of water :: 136 : x X 18. 
What is the formula of gypsum? 
27. Conditions for Rapid Solution. 
a. Take two large crystals of cupric sulphate of equal size, 
and yet of such size that each can be slipped into a test-tube. 30 
WATER AND SOLUTION 
[§ 28 
Provide two dry test-tubes with corks to fit. Pulverize one of 
the crystals very finely in the mortar, so that no large particles 
are visible. Place the powder in one test-tube and the crystal 
in the other. Add from the graduated cylinder 20 c.c. of 
water to each. Cork the tubes quickly, note the time on a 
watch (?), and shake the tubes quickly and continuously. Note 
the time when the powder has all dissolved (?) 
and when the crystal also has dissolved (?). 
Compare the total times required for each (?). 
Account for the difference (?). 
b. Take again two nearly equal-sized, but 
smaller crystals of cupric sulphate. Fill two 
test-tubes with water. Put one of the crystals 
into one of the tubes. Drop the other crystal 
into the second tube (Fig. 13), so that it is covered 
by the water, but rests on a narrow strip of ordi- 
nary paper. Note the time (?). Set both tubes 
upright in the rack. How long does each crystal 
take to dissolve? Account for the difference (?). 
If you had to dissolve a large amount of material quickly, 
with the least expenditure of effort, how should you proceed 
(In answering, take the results of both a and b into account)? 
c. On to a strip of paper dipping under water (Fig. 13), drop 
a crystal of potassium permanganate (?). Explain (?). 
28. Choice of Solvents. 
a. Place 1 c.c. of powdered rosin in each of two dry test-tubes. 
Add to one 5 c.c. of alcohol and to the other 5 c.c. of water and 
shake both (?). 
Pour the alcoholic liquid into a large beaker full of water. In 
what ways is a suspension like a solution (?) and how does it differ? 
Should you remove rosin (or varnish or a similar gum) from 
clothing with water? With alcohol? 
b. Place a small piece of lard, half the size of a pea, in each 
of two test-tubes. Add 2 c.c. of water to one and 2 c.c. of carbon 
tetrachloride* (or carbon disulphide or ether) to the other and 
shake (?). How should you remove grease from clothing? 
(In removing a grease-spot, place the part flat on a piece of 
blotting paper, to absorb the solution, and rub the spot with a 
rag dipped in the solvent.) 
Fig- 13 
* Non-inflammable. Carbon disulphide or ether must not be used 
near a flame. §29] 
WATER AND SOLUTION 
31 
c. Use small pieces of solid paraffin as in b, employing water 
and gasoline (petrol) or benzene as solvents. 
d. Take 10 c.c. of water in each of three test-tubes. To 
one add a single drop of alcohol and shake. Does the alcohol 
dissolve? Add more alcohol, a few drops at a time, until about 
5 c.c. have been added. Has the amount added yet become 
greater than the water can dissolve? 
To the second tube add carbon tetrachloride (or carbon di- 
sulphide) in the same way, and answer the same questions (?). 
To the third add gasoline (or benzene) in the same way, and 
answer the same questions. 
If you had a mixture of sugar (which is soluble in water) 
with fat on a piece of cloth, how could you remove first one and 
then the other component of the mixture? 
29. Degrees of Solubility. 
a. Place 1 c.c. of pulverized calcium sulphate in a test- 
tube and shake with 10 c.c. of water for 2-3 minutes. Filter the 
mixture, catching a few drops of the clear filtrate on a watch- 
glass. Evaporate to dryness (?). Repeat with 1 c.c. of pul- 
verized calcium carbonate (chalk), rejecting the water with 
which it is first shaken (?). Compare the deposits on the watch- 
glasses (?). Which of these substances do you find to be more 
soluble? What are the amounts of these salts dissolved by 
100 c.c. of water at 18° [R Appendix IV]? In what ratio is 
calcium sulphate more soluble than calcium carbonate [R Ap- 
pendix IV]? In what ratio is calcium chloride more soluble 
than calcium sulphate [R]? Which of all these substances are 
spoken of as "insoluble"? 
What conclusion should you have drawn from mere shaking 
with water, without completing the test? 
Was the solution you evaporated saturated? Was it con- 
centrated? What is a saturated solution? 
p b. Take about 10 c.c. of water in a test-tube, add to it not 
more than 1 c.c. of lead nitrate solution, and mix. Now add 
about 2 c.c. of dilute hydrochloric acid (?). Repeat, heating 
the mixture to the boiling-point before adding the hydrochloric 
acid (?). Examine this tube again, after the contents have 
cooled (?). Interpret the result. Is lead chloride an "insol- 
uble" substance [R Appendix IV]? 
c. [Quant.] Reduce to a fine powder 10-15 g. of potassium 
dichromate, using the larger amount in warm weather, the 32 
WATER AND SOLUTION 
[§ 30 
smaller in cool. Prepare a saturated solution of the substance 
by placing it in a flask with 50 c.c. of water and shaking at 
intervals for ten minutes. So much of the solid must be taken 
that an undissolved residue remains. 
Take the final temperature of the solution. Now pour the 
clear solution into a burette attached to the ring-stand, filling 
the apparatus completely to the point of the nozzle with the 
liquid (7 6). Read the level of the lower side of the meniscus. 
Weigh [Quant.] a clean, dry evaporating-dish, run into it about 
22-24 c.c. of the solution, and weigh [Quant.] the dish and con- 
tents. Read also the level of the meniscus and note the exact 
volume of solution used. Now evaporate the weighed portion of 
the solution completely to dryness upon a water bath, or on a 
beaker of boiling water, and weigh again. Determine by dif- 
ference the weights of the dry dichromate here found, and of the 
water in which it was dissolved. Calculate from the data the 
weight of dichromate which would be dissolved by 100 c.c. of 
water at the observed temperature (?). 
From the volume of the part of the solution evaporated, and 
the weight of dichromate found in it calculate also the molar 
solubility [R 183] of potassium dichromate at the observed 
temperature. Compare the results with those which would be 
obtained with potassium chromate K2CrO4 (Appendix IV) (?). 
30. Solution: Gases in Liquids. Half fill a 1-liter bottle 
with distilled water, cork, and shake vigorously till the water is 
saturated with air. Take the temperature of the water and also 
the barometric reading. Fit a small flask (100 c.c.) with a one- 
hole cork and delivery tube (Fig. 14) and measure its content 
up to the lower surface of the 
cork. Completely fill the whole 
apparatus, including the de- 
livery tube, with the prepared 
water, and boil, collecting the 
gas in a small test-tube in- 
verted over water. When no 
more gas comes over, equalize 
the levels of the water in the tube and trough (or beaker) and 
mark the level in the tube with a thin rubber ring (cut this 
from a piece of rubber tubing). Measure the volume which the 
air occupied. Correct the volume for the aqueous vapor present 
only, obtaining thus the volume of the air when dry and at the 
Fig. 14 §33] 
WATER AND SOLUTION 
33 
observed temperature and pressure. Calculate the volume of 
air dissolved by 100 c.c. of water at the observed temperature 
and pressure (?). What proportion of its own volume of air 
has the water dissolved? 
31. Two Immiscible Solvents; Extraction. Place one small 
particle of iodine in each of three test-tubes and add to one 
water, to the second potassium iodide solution, to the third car- 
bon disulphide, and shake each (?). If any iodine remains un- 
dissolved, pour off that solution into a clean test-tube. Now 
add a drop or two of carbon disulphide to the first two solutions, 
shake again (?), and describe carefully what seems to have 
happened. Deduce from this the relative solubility of iodine 
in the three solvents. 
32. Temperature and Solubility. 
a. Take about 6 g. of the dichromate and boil with 10 c.c. 
of water in a test-tube. How does the solubility differ from 
that found in 29 c? Allow the clear solution to cool (?). Ex- 
plain the result. What sort of curve of solubility would this 
substance exhibit (Appendix V)? Draw a curve of this type in 
your notes (?). 
Warm the contents of the tube carefully once more until all 
has dissolved. Then hold the tube in running water to cool it 
rapidly (?). Describe the contents (?). Note two differences 
(in size of particles and in color) between the results of slow and 
of rapid cooling and explain each (?). 
b. Take about 6 g. of sodium chloride and boil with 10 c.c. of 
water in a test-tube. Pour the clear liquid immediately into 
another test-tube. Examine this when cool (?). Is salt much 
less soluble in cold than in boiling water? How would its curve 
of solubility differ from that of potassium dichromate? Draw 
a curve of this type in your notes (?). 
33. Supersaturated Solution. Heat some anhydrous sodium 
sulphate strongly in a porcelain dish and allow it to cool. Take 
about 10 c.c. of water in each of two test-tubes. To one por- 
tion add Glauber's salt, previously pulverized in a mortar, 
until, after shaking, a considerable excess remains undissolved. 
Saturate the other portion with the cold anhydrous sodium 
sulphate in the same manner. Perform the last operation 
rapidly, taking care not to introduce any particles of the hydrate, 
and do not let the solution stand before use. Now decant the 
two liquids into clean test-tubes, disregarding the cloudiness 34 
WATER AND SOLUTION 
[§ 35 
of one of them. Then add a little of the anhydrous substance 
to the solution first made and a small crystal of Glauber's 
salt to the contents of the second test-tube and shake both (?). 
After a short time, examine the contents of each again (?). 
Interpret the results [R 193]. 
34. Freezing-Points, Deliquescence, Boiling-Points. 
a. If pulverized ice were to be added to water until the solid 
no longer melted, what would be the temperature of the mixture? 
If ice were to be added to the aqueous solution of some sub- 
stance, until the ice no longer melted, how would the tempera- 
ture differ from that of water and ice? Why does this difference 
exist [R 199]? Why does salt thrown upon ice cause the latter 
to melt? 
b. Place some dry potassium carbonate (or pulverized cal- 
cium chloride) in a small beaker or crucible. Set the vessel in 
an evaporating dish containing water, and invert over it a 
larger beaker so that the edge of the latter is under the liquid. 
Examine the material from day to day (?). Remembering that 
there is moisture upon the surface of even "dry" bodies, and 
that therefore a solution of potassium carbonate was present 
with the solid, explain the change [R 197]. To what class of 
substances do those which deliquesce all belong? Is deliques- 
cence a physical or a chemical change? 
c. Fix a test-tube containing about 10 c.c. of water in a 
clamp upon the ring-stand. Suspend the thermometer from a 
ring by means of a thread, in such a way that the bulb is im- 
mersed in the water. Boil the water, using a small Bunsen flame, 
and read the temperature (?). Now add to the boiling water 
about 2-3 g. of dry calcium chloride and, after solution is com- 
plete, read the temperature of boiling again (?). Add another, 
equal portion of calcium chloride, boil, and repeat the tem- 
perature reading after the whole has dissolved (?). Explain 
[R 198]. 
35. Properties of Solutions: Volume Changes and Thermal 
Effects. 
a. [Quant.] Take about 25 g. of potassium carbonate and 
determine its weight to the nearest tenth of a gram. Assum- 
ing the specific gravity of this substance to be 2, calculate the 
volume of the amount you have taken (?). Place in the gradu- 
ated cylinder exactly 85 c.c. of water and take its tempera- 
ture. What is the sum of the volumes of the water and the §35] 
WATER AND SOLUTION 
35 
carbonate, separately? Add the weighed specimen of potas- 
sium carbonate to the water, dissolve by repeated inversion 
of the cylinder, closing the mouth of the latter with the hand, 
and read the volume of the solution (?). Read also the tem- 
perature of the solution immediately (?). Is there a change in 
volume, or in temperature, on dissolving these two substances in 
one another? 
What relation exists between the sign of the thermal effect 
when a substance is dissolved in a nearly saturated solution of 
the same substance, and the change of solubility with tem- 
perature [R 305]? What do you infer in this case? 
6. Examine the solubility curve of anhydrous sodium sul- 
phate [R 193] (?). Will this compound give out or absorb 
heat in dissolving in water [R 305]? Verify your conclusion 
by trying the experiment (?). 
c. Repeat a, using about 25 g. of ammonium chloride (sp. 
gr. 1.5). Make the same observations and answer the same 
questions, CHAPTER VI. 
HYDROGEN CHLORIDE AND CHLORINE. 
36. Preparation of Hydrogen Chloride. 
a. [Hood] Place small quantities of ammonium chloride, 
barium chloride, mercuric chloride, and sodium chloride in as 
many test-tubes, and add a few drops of concentrated sulphuric 
acid to each (?). Describe what happens in each case. Note 
the odor (?) and color (?) of the gas. Blow moist air across the 
mouth of the test-tube (?). Lower a glass rod dipped in am- 
monium hydroxide solution into pach [Note 34, below]. Try 
the effect of heating. Remember that the solubility (physical) 
of the substance in sulphuric acid will largely determine the 
speed of the action. In case of difficulty, therefore, take a fresh 
sample of the solid, pulverize it finely, and shake with the acid 
for some minutes before heating and testing. Arrange the sub- 
stances in order of apparent activity (?). 
b. To a pinch of finely powdered sodium chloride add a 
strong solution of phosphoric acid and heat if necessary [R 207] 
(?). Test with ammonia as before 
(?). The above remark about solu- 
bility applies also to this case. 
Why is hydrogen chloride dis- 
placed completely in a and b by 
these acids under these conditions 
[R 208]? 
c. [Hood] In a 250 c.c. flask 
(Fig. 15), fitted with dropping-fun- 
nel (or substitute, 44 6) and L-shaped 
delivery tube, place about 30 g. of 
common salt. Use the shortest possible rubber connections 
here, and in 39 b (chlorine), as rubber tubing is destroyed 
by these gases. Admit concentrated sulphuric acid through 
the funnel. Collect the gas in three dry bottles by upward 
displacement. Cover, when filled, with glass plates and reserve 
for 37. Place about 10 c.c. of distilled water in a test-tube, 
Fig. 15 
36 §37] 
HYDROGEN CHLORIDE 
37 
attach a nozzle to the delivery tube, and allow the gas to 
bubble into this for a few minutes (?). Reserve the aqueous 
solution also for 37. Write equations for the two possible 
interactions of salt and sulphuric acid. Which of the two takes 
place under the above conditions? 
Note 34. - The use of ammonia is not a specific test for hydro- 
gen chloride. It can be used only for ascertaining the presence or 
absence of any one of several gases, usually of acidic character, 
which are capable of uniting with ammonia. 
In writing the equation here, and whenever the same test is 
used, consider whether the interaction took place with the liquid 
on the rod (containing NH4OH), or with the gas (NH3) given off by 
this liquid. Note the odor of this gas (?). 
37. Properties of Hydrogen Chloride and of Hydrochloric 
Acid. 
a. Invert one of the bottles of the gas in a dish of water (?). 
Relate this property to that observed on blowing moist air 
into the gas (36 a). If any gas remains, what should you ex- 
pect it to be? Test your conclusion experimentally. 
b. Pour a little ammonium hydroxide solution on a strip of 
filter paper and plunge this into the second bottle (?) [Note 
34, above]. Describe the difference between these fumes and 
those formed by the action of moist air upon the gas (36 a). 
c. Devise a way of proving, in a rough way, that the gas is 
heavier than air, and use the third bottle of gas for trying it. 
d. Six properties of hydrogen chloride have been considered. 
Make a list of these, and note opposite each whether it is a 
physical or a chemical property (?). 
Perform the following experiments with the aqueous solu- 
tion prepared in 36 c. 
e. Test the solution with litmus paper. 
f. To a part add some zinc dust (?). 
g. To a part add a crystal of sodium carbonate [R 573] (?). 
h. Dilute the remaining portion of the acid solution with an 
equal volume of water and distribute it between three test- 
tubes. To one test-tube add a drop or two of mercurous nitrate 
solution (?), to the second a drop of lead nitrate solution (?), and 
to the third a drop of silver nitrate solution (?). After allowing 
the contents of each tube to settle, pour away the liquid, add 
water, and boil (?). Allow to cool, and note, by the appear- 38 
CHLORINE 
[§39 
ance of crystals, which of the precipitates is soluble in hot 
water. 
These precipitates are given, not only by hydrochloric acid, 
but by any chloride, and are, therefore, means of recognizing 
the presence of the chloride radical which is common to all 
chlorides. 
38. Theory of the Method Used in Preparing Hydrogen 
Chloride. To a concentrated solution of sodium-hydrogen 
sulphate add pure concentrated hydrochloric acid (?). Add 
the acid a very little at a time to avoid over-rapid precipita- 
tion, and agitate between additions. The longer the operation 
takes, the better. Examine the result with a lens (?). 
Write the equation for this action. What relation does this 
action bear to that in 36 c? What circumstances determine 
the direction of a reversible action [R 208]? 
39. Preparation of Chlorine [Hood]. 
Experiments 39 6 and 40 must be accomplished at one ex- 
ercise. 39 a may be postponed to facilitate this. 
a. Prepare some strips of filter paper by dipping them in 
starch emulsion to which you have added one drop of potassium 
iodide solution. 
Place small quantities of finely powdered manganese dioxide, 
potassium chlorate, lead dioxide, and pure litharge in as many 
test-tubes, and add a little concentrated hydrochloric acid to 
each. Notice the color (?) and odor (?) of the gas in each case. 
If no action takes place in the cold, apply heat. Dip into the 
gas in one of the test-tubes a strip of the prepared paper (?). 
How do you account for the difference in the behavior of the 
two oxides of lead? Do all compounds containing oxygen give 
free chlorine in this way? If not, state what is common to those 
which do and to those which do not (?). 
6. Fit up a 250 c.c. generating flask, as in Fig. 15, with a 
dropping-funnel (or substitute 44 6) and an L-shaped glass 
tube attached to the exit tube. Use the shortest possible 
rubber connections. Test the apparatus to see that it is 
air-tight. Place in the flask about 20 g. of dry potassium 
permanganate, and fill the globe of the dropping-funnel 
with diluted, concentrated hydrochloric acid (1 Aq. : 3 acid). 
[Caution! Do not use any other acid, by mistake.] Allow 
the delivery tube to dip to the bottom of a small beaker 
containing a little sodium hydroxide solution. Now admit the §40] 
CHLORINE 
39 
acid drop by drop, regulating the flow so that too rapid a stream 
of gas is not produced. The complete displacement of the air 
in the flask will be recognized by the color of the contents and the 
fact that the bubbles of pure chlorine are completely absorbed 
by the sodium hydroxide. 
When the air has all been displaced, fill three dry bottles and 
one dry test-tube with the gas by upward displacement, observ- 
ing the following precautions: Provide a piece of stiff paper or 
card, perforated with a hole for the reception of the delivery 
tube, to cover the bottles during the filling, and cover the ves- 
sels with glass plates as soon as they are full. See that the 
delivery tube reaches to the bottom (why?) of each vessel 
during the filling. Replace the end of the delivery tube in the 
sodium hydroxide when all the vessels have been filled. When 
the experiment is over, pour the contents of the generating 
flask into the sink in the hood, and not into one of the sinks in 
the open laboratory, and wash down with much water. 
40. Properties of Chlorine [Hood]. 
a. In one bottle of the gas scatter a pinch of finely pow- 
dered antimony [R 221] (?). 
b. Take a clean piece of sodium [From Instructor] and cut 
from it a very thin slice not more than one-half inch square 
(fingers and knife used in handling sodium must be dry!). In- 
troduce this piece into a bottle of chlorine (?) and cover at once 
with a glass plate. Examine after half an hour. If any of the 
metal remains unattacked, scrape off the white deposit and 
place it upon a watch-glass, and throw the sodium into the 
sink in the hood. Add the material on the watch-glass to 
that in the bottle and dissolve in 2 c.c. of water. Allow the 
solution to stand in a watch-glass until it dries, and examine 
the crystals with a lens (?). 
c. Connect a glass nozzle with the illuminating-gas supply, 
and lower a small, burning gas-jet into the third bottle (?). 
Blow the breath into the bottle after withdrawing the 
jet (?). 
d. Fill a test-tube with hydrogen from a Kipp's apparatus 
or from the laboratory supply. Bring this tube mouth to 
mouth with a tube of chlorine and mix the gases by repeated 
inversion. (Take care not to expose the mixture to direct sun- 
light.) Hold the mouth of each tube to the Bunsen flame (?). 
Close the mouth of one tube quickly with the thumb, add a 40 
CHLORINE 
[§ 40 
few drops of water, shake, and test the solution with litmus 
paper (?). 
e. Seven properties of chlorine have been considered. Make 
a list of these, and note which of them are physical and which 
chemical (?). CHAPTER VII. 
EQUIVALENT WEIGHTS, FORMULAS, EQUATIONS. 
41. Composition of Carbon Dioxide [Quant. Two students 
working together]. Fit a piece of hard glass tubing, 25-30 cm. 
long, with perforated corks. Insert at one end a short piece 
of glass tubing and at the other a U-tube, as in Fig. 16. The 
inner edges of the hard glass tube should be rounded with a 
file, or flared by use of the blast-lamp and a piece of charcoal. 
Fig. 16 
Rubber stoppers will give tight joints more surely than corks. 
Attach to the U-tube by means of a cork a short, straight tube, 
of the diameter of a narrow test-tube, which has been drawn 
out [Bunsen flame] so as to leave a small opening at the free 
end. Arrange a loop of thread with which to suspend the 
U-tube from the balance. Place in the hard glass tube a plug 
of granular cupric oxide, about 4 cm. in length. This may be 
held in position by small wads of asbestos. The cupric oxide 
and asbestos must be dried by heating in the porcelain crucible 
before use. Put about 0.2 g. of pure dry sugar-charcoal [In- 
structor] in a porcelain boat, weigh the boat with contents, 
counting the weights as described in Note 23 (p. 8), and set it 
in the tube close behind the cupric oxide. Make a few c.c. of a 
strong (approximately 30 per cent) solution of potassium hy- 
droxide, fill the bend of the U-tube with it, and charge the small 
tube beyond with fragments of solid caustic potash. Test the 
apparatus with the greatest care to see that it is absolutely air- 
tight [Instructions]. Finally, immediately before starting the 
combustion, weigh the connected potash tubes, replace them in 
position, and test once more for air-tightness. 
41 42 
EQUIVALENT WEIGHTS 
[§42 
Slip a cylinder, made by rolling a piece of wire gauze, over 
the hard glass tube, connect the latter with the oxygen cylin- 
der (or other source of oxygen), and heat the part containing 
the boat and cupric oxide with two burners (extra Bunsen 
burner from storeroom). Turn on the oxygen with care and 
regulate the stream so that the carbon may burn slowly and 
not more than 15-20 bubbles of unused oxygen escape per 
minute. A more rapid stream will involve the loss of carbon 
dioxide. Heat the front of the boat first (why?) and let the 
glow, caused by the combustion, travel along. The burning will 
take 30-45 minutes. Continue the stream of oxygen for 4-5 
minutes after the carbon is completely burned (why?), then dis- 
connect the potash apparatus and weigh it. A more accurate 
result is obtained by finally displacing the oxygen by air (why?). 
After the tube has cooled, weigh the boat with any ash it may con- 
tain. Return the cupric oxide to the bottle. 
The loss in weight of the boat gives the amount of carbon; 
the gain in weight of the potash apparatus, the amount of the 
carbon dioxide. The difference of these two gives the oxygen. 
Calculate from your data the weight of carbon combining 
with 8 parts of oxygen. 
Wt. of ox. found : Wt. of carbon found :: 8 : x. 
This gives x, the equivalent [R 63] of carbon. This weight 
of carbon is equivalent to those amounts of other elements 
which likewise unite with 8 parts of oxygen. 
Assuming the atomic weights of carbon and oxygen to be 
12 and 16 respectively, calculate from your data the formula of 
carbon dioxide [R 71]. 
Make the equation representing the action. 
42. Composition of an Oxide of a Metal [Quant. Note 22, 
p. 7]. On account of the difficulties attending the making, 
the collecting, or the weighing of most oxides formed by direct 
union, the following indirect method is suggested. It consists 
in converting a known weight of a metal into the nitrate of the 
metal by the action of nitric acid, and obtaining the oxide by 
decomposition of this salt. Make no equations for these actions. 
a. Composition of an oxide of iron. Weigh an evaporating- 
dish of medium size, counting the weights as described in Note 23 
(p. 8), place in it about 1 g. of pure iron wire, and weigh again. 
Cover the dish with a watch-glass, convex side downward, and §42] 
EQUIVALENT WEIGHTS 
43 
add 10 c.c. of pure dilute nitric acid. Set the dish, covered, on 
the water bath until the iron has dissolved, adding a few drops 
of concentrated nitric acid if any of the wire remains unattacked 
[Instructions]. Then rinse the cover-glass carefully into the 
dish and remove it, and evaporate the solution to dryness on the 
water bath or on a beaker of boiling water [Hood]. When the 
residue (what is it?) is dry, place the dish on a clay triangle sup- 
ported on the ring-stand and heat carefully with a burner held 
in the hand as long as any red fumes are given off. During this 
process, and especially at first, great care and patience must be 
exercised, as too rapid heating may cause solid particles of the 
product to be thrown from the vessel. If any crackling noise is 
observed, remove the burner at once. When, after final strong 
heating of every part of the material, red fumes or other evidence 
of continued change can no longer be perceived, allow the dish 
and contents (?) to cool and weigh them. To make sure that 
the decomposition was complete, heat once more, cool, and 
weigh again. This "heating to constant weight" is always 
necessary in experiments of this nature. 
Before cleaning out the dish, show the results of the calcula- 
tion (below) to an instructor. If the percentage of oxygen is 
too low, and no loss from spirting occurred, some iron may have 
remained unattacked. To remedy this, moisten with concen- 
trated nitric acid, heat once more, and weigh (?). 
Wt. of crucible + iron g. 
Wt. of crucible, empty g. 
Wt. of iron g. 
Wt. of crucible + oxide of iron g. 
Wt. of crucible + iron g. 
Wt. of oxygen g. 
Wt. of crucible + oxide of iron g. 
Wt. of crucible, empty g. 
Wt. of oxide of iron g. 
Calculate from your results the percentage composition of the 
oxide of iron (?). 
Calculate from your data the weight of iron (x) combining 
with 8 parts of oxygen: Wt. of ox. found : Wt. of iron : : 8 : x. 44 
EQUIVALENT WEIGHTS 
[§43 
This is the equivalent weight [R 63] of iron m this oxide. 
This weight of iron is equivalent to those amounts of other 
elements which likewise unite with 8 parts of oxygen. 
Assuming the atomic weights of iron and of oxygen to be 55.8 
and 16, respectively, calculate from your data the formula of 
the oxide of iron [R 71]. What is the name of this oxide? What 
other oxides of iron are known [R]? What is the valence of 
iron in this oxide? 
b. Pure zinc (about 1 g.) may be used instead of iron. The 
manipulation is the same as in 42 a. The residue from evapo- 
ration is a syrup-like body, however, which cannot be dried. 
Extra caution must, therefore, be used in heating this to avoid 
loss by spirting. 
Tabulate the results as shown in 42 a, and make the corre- 
sponding calculations (?). 
c. Magnesium wire (about 1 g.) may be used instead of zinc 
(42 6). Equal care is required during 
the evaporation and heating. Tin 
(about 1 g.) may also be used. 
43. Composition of a Sulphide of 
a Metal [Quant.]. Weigh the crucible 
(without cover) to the nearest centi- 
gram, counting the weights as de- 
scribed in Note 23 (p. 8). Place 
about 2 g. of "reduced" nickel (do 
not attempt to take this amount, ex- 
actly) in the crucible and weigh again. 
Set down the weighing as shown be- 
low. Put about 2 g. of sulphur in 
the crucible and set the latter on the 
pipestem triangle (Fig. 17). Set the 
cover on the crucible, and heat gently 
so long as sulphur vapor burns [Hood] at the chink between the 
crucible and cover. Heat strongly for 1-2 minutes. Then hold 
the flame against the upper portion of the crucible, so that all 
free sulphur may be driven off. When the crucible is cold (not 
before), remove the cover and weigh. 
Wt. of crucible 4- nickel g. 
Wt. of crucible, empty . g. 
Wt. of nickel taken g. 
Fig. 17 §44] 
EQUIVALENT WEIGHTS 
45 
Wt. of crucible + nickel sulphide g. 
Wt. of crucible + nickel g. 
Wt. of sulphur combined g. 
Wt. of crucible + nickel sulphide g. 
Wt. of crucible, empty g. 
Wt. of nickel sulphide g. 
Calculate the percentage composition of nickel sulphide (?). 
From your results, calculate the formula of nickel sulphide 
[R 71] and show in your notes the method of calculation (?). 
Make the equation for the union of nickel and sulphur. 
44. Equivalent Weight of a Metal by Displacing Hydrogen 
[Quant.]. 
a. First fill the pneumatic trough and 1-liter bottle with 
water so that the liquid may acquire the temperature of the 
room. Fit a 100 c.c. flask somewhat as in Fig. 11, using in place 
of the thistle-tube a dropping-funnel (see 44 6). To carry a 
doubly-bored cork the mouth of the flask must be rather wide. 
A larger flask than 100 c.c. must not be employed on account 
of the waste of acid its use would entail. A sufficiently wide test- 
tube, or a w.-m., 90 c.c. bottle, however, may be used. The stem 
of the dropping-funnel must reach to the bottom of the flask (or 
test-tube, or bottle), and the inner end of the L-tube must not 
project below the bottom of the cork. Attach a rubber or glass 
delivery tube and see that the apparatus is air-tight. Weigh a 
piece of chemically pure zinc, taking about 2 g. Without de- 
taching your platinum wire from the glass rod, wrap it tightly 
round the zinc (why?) and allow the whole to slide gently into 
the flask. Fill the apparatus completely, from the top of the 
stem of the funnel to the tip of the delivery tube, with water. 
Close the stopcock when the bulb has almost emptied itself. 
Invert the 1-liter bottle, filled with water, on the shelf of the 
pneumatic trough, and put the delivery tube in position. 
Fill the globe of the funnel with pure concentrated hydro- 
chloric acid and admit this to the flask, a little at a time, in such 
a way that a steady, but not too violent, action takes place. A 
good deal will be needed at first before sufficiently rapid action 
begins (why?). When the metal is entirely dissolved, drive all 
the gas over into the bottle by pouring water once more through 
the funnel (be careful that no air is carried over with the water). 46 
EQUIVALENT WEIGHTS 
[§ 44 
The weight of the hydrogen which has been displaced by the 
weighed quantity of zinc is to be ascertained in this experiment, 
not by direct weighing, but by measuring the volume of the gas 
and calculating its weight from this and the density of hydrogen: 
When the gas has acquired the temperature of the water and 
room, lower the bottle until the level of the water outside and 
inside is the same. If there is still a good deal of water in the 
bottle, the latter may have to be inclined to accomplish this 
and the following operation. Close the bottle with a cork while 
it is in this position and remove it from the trough. To find 
the volume of the gas, measure with the graduated cylinder the 
volume of water required to completely fill the bottle (?). The 
volume of water needed is equal to the number of c.c. of hydro- 
gen. Record the temperature of the hydrogen by reading a 
thermometer hung in the laboratory close to the apparatus. 
Read the barometer, and record the corrected reading [Note 32, 
p. 21]. Since the hydrogen is mixed with water vapor, correct 
for the latter by subtracting the aqueous tension (Appendix II) 
at the observed laboratory temperature from the corrected baro- 
metric reading. This gives the true partial pressure of the 
hydrogen. 
Wt. of zinc taken g. 
Vol. of hydrogen obtained c.c. 
Temperature 
Barometric height (corr.) mm. 
Tension of aqueous vapor mm. 
Press, of hydrogen, corr mm. 
Vol. of hydrogen at 0° and 760 mm. . . c.c. 
Weight of this hydrogen g. 
Reduce the volume of the hydrogen, by rule, from the ob- 
served temperature and partial pressure to 0° and 760 mm. 
[R 110]. Find by calculation (1 liter weighs 0.09 gr. at 0° and 
760 mm.) the weight of the hydrogen obtained. Calculate the 
equivalent weight of zinc, i.e., the weight of the metal (x) which 
displaces 1.008 g. of hydrogen: 
Wt. of hyd. : Wt. of zinc :: 1.008 : x. 
Calculate from the result how many equivalent weights of 
hydrogen would be displaced by 65.4 g., the gram-atomic §46] 
EQUIVALENT WEIGHTS 
47 
weight, of zinc. What is the valence of zinc? How many for- 
mula-weights of hydrogen chloride are required to furnish the 
hydrogen displaceable by one atomic weight of zinc? Write 
the left-hand side of the equation in accordance with this 
result. 
Wash the trough carefully until it is absolutely free from 
acid, and put it away in an inverted position to avoid rusting. 
b. The above experiment may be performed with magne- 
sium (about 0.9 g.), iron (about 1.8 g.), or aluminium (about 0.8 
g.) in place of zinc. 
In the absence of a dropping-funnel, a substitute may be 
made by connecting a funnel with a straight tube by means of 
a rubber joint closed with a pinch clamp (Fig. 
18). Or, the aspirator (Fig. 10) may be used here, 
the metal (half the above quantities), water, and 
a smaller tube containing the acid being placed in 
the test-tube, and the mixing being effected by 
inclining the bottle after the apparatus is con- 
nected. 
45. Inter-Equivalence of Equivalent Weights 
(Law of Reciprocal Proportions). If 42 b was per- 
formed, compare the quantity of zinc which com- 
bined with 8 g. of oxygen with that which in 44 a 
was found to displace 1.008 g. of hydrogen. If 
they are identical, these two quantities of oxygen 
and hydrogen are chemically equivalent and may 
combine with one another. What substance has 
precisely this composition? 
If magnesium was used, in 44 b, compare the 
quantity with that combining, in 42 c, with 8 g. of oxygen and 
answer the same question. 
46. Combining Weights of Zinc and Chlorine [Quant.]. 
Weigh an evaporating-dish of medium size, place in it about 
2 g. of pure zinc, and weigh again (?). Add a little diluted (1 
aq. : 2 acid), pure, concentrated hydrochloric acid and cover 
with a watch-glass, convex side downward. If the action is 
very slow, the tip of a platinum wire may be placed in contact 
with the zinc. Maintain a brisk action by further additions of 
concentrated hydrochloric acid in very small amounts at a time. 
Final excess of the acid should be avoided, as time will be lost 
in the subsequent evaporation. When the metal is completely 
Fig. 18 48 
EQUIVALENT WEIGHTS 
[§47 
dissolved, rinse the cover-glass and platinum wire carefully 
into the porcelain dish and remove them. Allow the solution 
to evaporate as far as possible on the water bath or on a beaker 
of boiling water [Hood]. Now place the dish on the ring-stand, 
and, using a small Bunsen flame, allow the syrup-like solution to 
evaporate slowly to dryness. Then heat the white mass to the 
point at which it has completely melted and no further. The 
best way to achieve this with the minimum rise in temperature 
is to let the Bunsen flame play on the surface from above. Over- 
heating must be avoided, because the product is volatile at high 
temperatures. The moment the dish has so far cooled that the 
hand can be borne upon the bottom, wipe the dish carefully 
and weigh it. The substance absorbs moisture greedily from 
the atmosphere, hence expedition is required in cooling and 
weighing if accurate results are to be obtained. To insure 
accuracy, the melting, cooling, and weighing should be repeated, 
and the lower result taken as correct. 
Wt. of dish + zinc g. 
Wt. of dish, empty g. 
Wt. of zinc g. 
Wt. of dish + zinc chloride g. 
Wt. of dish + zinc g. 
Wt. of chlorine g. 
Calculate, from the data obtained in this experiment, how 
much chlorine combines with the equivalent weight of zinc 
found in 44 a. This amount is the equivalent weight of chlo- 
rine (x): 
Wt. of zinc : Wt. of chlor. : : Equiv. of zinc : x. 
Assuming the atomic weights of zinc and chlorine to be 65.4 
and 35.46 respectively, determine the formula of zinc chloride. 
Express the whole action of hydrochloric acid on zinc in 
symbols by making the equation in accordance with these con- 
clusions. Which of the factors in the equation have you de- 
termined experimentally, and which not? What law do we 
use in assuming that the undetermined factors are correct? 
47. Combining Weights of Lead or Silver and Chlorine. 
From the weights of lead (10) or silver (11 a) and chlorine §48] 
EQUIVALENT WEIGHTS 
49 
found to combine, calculate the formula of lead (or silver) 
chloride. 
48. Multiple Proportions [Quant.]. 
a. [Two students working together.] Fit a hard glass tube 
with corks through which pass short pieces of narrow glass 
tubing (Fig. 12). Fix the tube in a clamp upon the ring-stand, 
attaching the clamp close to one end so that the rubber cover- 
ing of the clamp may be away from the central part which is to 
be heated. Make sure that the apparatus is air-tight. Dry 
some pulverized cupric oxide by heating it in a hard glass test- 
tube. Weigh two clean, dry, porcelain boats, and place in one 
about 1.5 g. of the cupric oxide and in the other 2.5 g. or more 
of cuprous oxide * [From Instructor] and weigh each again. In 
recording the weights and in handling the boats be careful to 
distinguish the one from the other. Place the boats in the 
hard glass tube, so that the points of the boats touch in the 
center of the tube. Connect the end nearest to the cuprous 
oxide with a source of dry hydrogen (Kipp's apparatus and 
drying-bottle, or laboratory supply). 
Pass a gentle stream of hydrogen through the apparatus 
until a test (?) shows that the air has all been displaced. Re- 
duce (why?) the speed of the gas until the bubbles in the wash- 
ing-bottle can easily be counted. Now heat the boats moder- 
ately, beginning with that containing the cuprous oxide. What 
collects in the cooler end of the tube? Where does it come 
from? When the action, which requires 10-15 minutes, is 
finished, allow the boats to cool in a stream of hydrogen. Weigh 
the boats and contents (?), taking care not to interchange 
them. To ascertain whether the action is complete, heat the 
boats once more in hydrogen, cool, and weigh again. 
Determine by difference the weights of oxygen and copper in 
each case, and calculate from the data how much copper is 
combined with 8 parts of oxygen in each of the two oxides. 
What is the ratio of the two values of copper? Show that the 
result illustrates the law of multiple proportions. 
Assuming 16 and 63.6 to be the atomic weights of oxygen 
and of copper, respectively, calculate from the data the formula 
of each oxide. Construct the equations representing the action 
of hydrogen upon each oxide. 
* Pure cuprous oxide can be kept successfully if sealed up in small 
bottles, which are not opened until needed. 50 
EQUIVALENT WEIGHTS 
[§ 49 
b. Pure lead dioxide and pure lead monoxide may be used 
as in a, if available. The monoxide, however, absorbs carbon 
dioxide readily from the air, and therefore does not keep well. 
The experiment must, therefore, be tried by the instructor 
before the material on hand is given to the class. Lead mon- 
oxide is more difficult to reduce than is the dioxide. The heat- 
ing in a stream of hydrogen must be repeated to constant 
weight. 
c. If the quantitative decomposition of potassium chlorate 
(17 6) was carried out, dried potassium perchlorate may be 
decomposed in the same way and the results compared. Weigh 
an open, long, hard glass test-tube (?). Place in it about 1 g. of 
potassium perchlorate and weigh again (?). Then heat the tube 
and drive off the oxygen slowly, and weigh again (?). Heat 
strongly once more, to constant weight. Ascertain by differ- 
ence the weights of potassium chloride (residue) and of oxygen. 
The formula of the perchlorate is KCIO^. Calculate from 
your data how much oxygen (CV) is combined with 74.56 g., the 
formula-weight, of potassium chloride (KC1). This result, the 
formula-weight of the oxygen, will be a multiple of 16. Com- 
pare this formula-weight of oxygen with that found in the 
experiment with potassium chlorate, and show how the results 
illustrate the law of multiple proportions. Find the formula 
of potassium perchlorate and write the equation for the decom- 
position of the compound. 
49. Dulong and Petit's Law. According to Dulong and 
Petit [R 245], if the correct atomic weight, when it has been 
found, is multiplied by the specific heat of the element in the 
solid form, the product is a number which in most cases lies 
between 6 and 6.8. 
Take the values of such equivalent weights as you have found 
experimentally, viz., iron (42 a, 44 6), zinc (42 b, 44 a), magnesium 
(42 c, 44 6), aluminium (44 6), silver (47), copper (48 a, two 
values), or lead (47, one value, and 48 b, two values), and mul- 
tiply each by the corresponding specific heat (Appendix III). 
If the result is about 6.4, the atomic weight is the same as the 
equivalent weight. If not, multiply the equivalent weight by 
the smallest integer which will bring the final product within the 
limits 6 to 6.8. The integer used is the valence of the element, 
and the product of the equivalent weight and the valence is the 
atomic weight. Show the working in your notes and give a list §50] 
EQUIVALENT WEIGHTS 
51 
of the atomic weights and valences found. In the case of 
copper or lead, distinguish the valences in the two compounds. 
50. Molecular Weight of an Insoluble Gas [Quant.]. 
a. Fit a round-bottomed 300 c.c. flask [Storeroom] with a 
rubber stopper through which passes a short glass tube. To the 
latter attach a short rubber tube with an open screw clip [Store- 
room]. Place 40 to 50 c.c. of water in the flask, boil the water 
vigorously for about ten minutes to expel the air from the flask. 
Lower the flame, close the clip, and then at once remove the 
flame. 
Wt. of flask and water + air g. 
Wt. of flask and water g. 
Wt. of air g. 
Vol. of flask (total) c.c. 
Vol. of water (remaining) c.c. 
Vol. of air c.c. 
Barometic height (corr.) mm. 
Tension of aqueous vapor mm. 
Pressure of air, corrected mm. 
Temperature 
Wipe the flask, and weigh it when cold (?). Open the clip 
slowly to admit air, and weigh again (?). Record the weights 
(see above). The increase is the weight of the air which en- 
tered. To learn its volume, measure in the graduated cylinder 
the volume of the water remaining (?), and then the total 
volume required to fill the flask to the bottom of the stopper (?). 
Record also the temperature (?) and barometric pressure (corr.) 
(?) and subtract from the latter the tension of the aqueous 
vapor in the flask (Appendix II). 
Reduce the volume of the air from the observed temperature 
and barometric pressure (as corrected), to 0° and 760 mm. 
From the weight of the air, and its volume at S.T.P., calculate 
the density (wt. of 1 c.c.) of the air (?) and also weights of 1 
liter (?), and of 22.4 liters (?). 
b. By admitting other gases, instead of air, this method 
may be used for measuring the densities of gases which are 
insoluble in water. Name several gases to which this method 
could be applied (?). 52 
EQUIVALENT WEIGHTS 
[§ 51 
By calculating from the results the weights of 22.4 liters, 
the molecular weights of such gases are obtained. 
51. Calculations. 
a. The weights of 1 G.M.V. (22.4 liters at 0° and 760 mm.) 
of several compounds of carbon are as follows: 
Substance. 
Wt. 
22.41. 
Wt. 
carb. 
Wt. 
hyd. 
Wt. 
ox. 
For- 
mula. 
Carbon monoxide.. 
28.00 
12 
16 
Carbon dioxide 
44.00 
12 
32 
Methane 
16.032 
12 
4.032 
Ethylene 
28.032 
24 
4.032 
Glycerine (vapor). . 
92.064 
36 
8.064 
48 
What value should you select for the atomic weight of car- 
bon? The atomic weight and symbols being: hydrogen H = 
1.008, oxygen 0 = 16, carbon C = ?, write the formula of each 
of the five compounds (?). 
b. The density (wt. of 1 c.c. at 0° and 760 mm.) of ethylene 
chloride is 0.00433 g. What is the molecular weight? 
c. Using the weights of 22.4 1., given above, find the weight 
of 1 c.c. (the densities) of methane and of carbon dioxide (?). 
d. How do the densities of the five substances compare with 
that of air? CHAPTER VIII. 
BROMINE, IODINE, FLUORINE, AND THEIR COMPOUNDS 
WITH HYDROGEN. 
Chlorine (Chap. VI) and the elements to be studied in this 
chapter form a group having very similar properties, and are 
called the halogens. Recall the facts about chlorine and hydro- 
gen chloride and use them as a guide in trying to understand 
the chemistry of the rest of the group. Remember particularly 
that chlorine is colored, has a powerful odor, and does not 
cause fumes in moist air; and that hydrogen chloride is color- 
less, and causes dense fumes in moist air. The corresponding 
substances throughout the group may be expected to present 
properties like these. Thus,, the, elements are all colored sub- 
stances, the hydrogen compounds are all colorless and fume 
in moist air. The hydrogen compounds, hydrogen chloride, 
hydrogen bromide, etc., are known as the hydrogen halides. 
52. Preparation of Bromine [Hood]. Powder about 1 g. of 
potassium bromide, mix it in the mortar intimately with about 
2 g. of pulverized manganese dioxide, and place the mixture in 
a test-tube. In a second test-tube dilute 2-3 c.c. of concen- 
trated sulphuric acid with half its volume of water (add the 
acid, cautiously, to the water), and mix with the contents of the 
first test-tube enough of this solution to moisten the materials 
thoroughly, and no more. After allowing the mass to stand 
for a few minutes, apply a gentle heat to the tube, and note 
the color and behavior of the vapors evolved (?). Apply a 
strip of filter paper moistened with a starch-potassium iodide 
emulsion (39 a) to the mouth of the tube (?). 
What other materials might be substituted for the potassium 
bromide in the above experiment? 
53. Properties of Bromine. 
Shake up one drop of bromine [care. Do not spill upon the 
hands] with 10 to 15 c.c. of water in a test-tube, and divide the 
solution ("bromine-water") between four test-tubes. 
a. To one of these add 1-2 c.c. of ether, and shake (?). Note 
53 54 
BROMINE, IODINE, FLUORINE 
[§ 54 
the relative solubility of bromine in ether and in water as dis- 
played by the depth of color in each layer (31). To the sec- 
ond add carbon disulphide (?), and to the third chloroform 
(?), observing as before. To about 10 c.c. of starch emulsion 
add a few drops from the fourth test-tube (?) [R 271 and see 
result of 57 b, below]. 
b. Fit up an apparatus to generate a small amount of chlorine 
[Hood], using a side-neck test-tube instead of the flask in Fig. 
15 (p. 36). If chlorine-water is available, it may be used instead 
of the gas. 
Dissolve a single, very small crystal of potassium bromide in 
a few c.c. of water in a test-tube. Add several drops of carbon 
disulphide, and then pass a few bubbles of chlorine through the 
solution, or add a few c.c. of chlorine-water (?). Shake, and 
notice the appearance of color in the carbon disulphide (?). 
Infer from this result the relative activities of chlorine and bro- 
mine (?). The result measures the relative affinity of chlorine 
and bromine for what elements? 
The chlorine generator, if used, is required again in 57 c, 
which may be performed at once, before the apparatus is taken 
apart and cleaned. Prepare also 5 c.c. of saturated chlorine- 
water, if not furnished on the side-shelf, cork it up in a test- 
tube, and set it aside in a dark place for use in 55 g and 60 a. 
54. Preparation of Hydrogen Bromide. 
a. Pulverize about 1 g. of potassium bromide, place it in a 
test-tube, and cover with concentrated phosphoric acid solu- 
tion. Notice the apparent slow- 
ness of the action on account of 
the insolubility (physical) of the 
compound in the liquid (sodium 
bromide is much more soluble, 
and should be used, if available). 
Warm, if necessary. Observe the 
odor (?), and insert a rod dipped 
in ammonium hydroxide solution 
(?) [Note 34, p. 37], 
For the action of sulphuric acid with a bromide, see 62 b. 
b. Fit up a 250 cc. flask with a dropping-funnel and exit 
tube, and connect with a U-tube (Fig. 19). Render the ap- 
paratus air-tight. Fill the U-tube with dry, broken glass or por- 
celain, mixed with a little red phosphorus (why?). Connect the 
Fig. 19 § 56] 
BROMINE, IODINE, FLUORINE 
55 
other limb of the U-tube with a second, larger U-tube [Store- 
room] containing about 10 c.c. of water. Place about 5 g. 
of red phosphorus mixed with twice its weight of sand in 
the flask, add 5 c.c. of water, and mix by shaking. Pour into 
the globe of the funnel about 8 c.c. of bromine [Extreme care. 
Do not spill upon the hands (Note 16, p. 2)]. Allow the bromine 
to flow drop by drop on to the phosphorus, and let the gas 
dissolve in the water in the second U-tube. A large volume 
of air is expelled before the hydrogen bromide reaches the 
second U-tube. Disconnect the second U-tube and reserve 
the solution for use in 55. 
Try the effect of moist air upon the gas issuing from the 
main apparatus (?). Hold in the gas a rod dipped in ammo- 
nium hydroxide (?). 
55. Properties of Aqueous Hydrobromic Acid. Divide the 
solution into seven portions and examine its behavior toward 
(a) litmus (?), (6) zinc in contact with a platinum wire (?), 
(c) silver nitrate solution (?), (d) mercurous nitrate solution 
(?), (e) lead nitrate solution (?), (J) powdered manganese di- 
oxide (warm) (?). Boil c, d, and e, after pouring away the 
supernatant liquid and adding more water to each (?). Com- 
pare these results with those found in the case of hydrochloric 
acid (37). 
g. To the seventh portion add a few drops of chlorine-water 
(53 6), a few drops of carbon disulphide, and shake (?). This 
result indicates the relative affinities of chlorine and bromine 
for what elements, and how? 
56. Preparation of Iodine. Prepare a mixture of potassium 
iodide (1 g.) and manganese dioxide (2 g.) exactly as in 52, 
place it in an evaporating-dish, and moisten (2-3 drops) with 
sulphuric acid diluted with water (1 Aq. :2 acid). Cover the 
dish with a watch-glass (partially filled with cold water to cool 
the surface presented to the vapors) and warm very gently. 
After a time examine the sublimate [Note 35, below]. Expose 
a strip of filter paper, moistened with starch emulsion alone, 
to the vapors (?). Recall the interaction of chlorides with 
manganese dioxide and sulphuric acid [R 220]. 
What other materials might be substituted for potassium 
iodide in preparing iodine? 
Note 35. -• Stains upon the fingers caused by iodine may be 
removed by rubbing with sodium thiosulphate solution ("hypo"). 56 
BROMINE, IODINE, FLUORINE 
[§ 59 
57. Properties of Iodine. Shake a few crystals of iodine 
vigorously [Note 35] with about 10 c.c. of water in a test-tube. 
Pour the clear liquid off, dividing it equally between four 
test-tubes. 
a. Add to one portion a few drops of chloroform, to another 
ether, and to a third carbon disulphide. Shake each vigor- 
ously and note the relative solubility (estimated by depth of 
color) of iodine in water as compared with that in each of the 
other solvents (?). 
b. Take 15 c.c. of starch emulsion and add the fourth portion 
to it (?). Pour the mixture into the graduated cylinder and 
add water so long as a sample poured out into a test-tube con- 
tinues to show an easily perceptible color. Why is the use of 
starch considered to be a delicate test for iodine? Does it 
show the presence of iodine in combination (58 6)? 
c. Repeat 53 b, using a very small crystal of potassium 
iodide (?). Infer the relative activities of chlorine and iodine. 
The result measures the relative affinities of these two halogens 
for what elements? 
d. Repeat c, using potassium iodide, but substituting bro- 
mine-water for chlorine. In what order do the halogens stand, 
in respect to activity, and why do you place them in that order? 
58. Preparation of Hydrogen Iodide [Hood]. 
a. Repeat 54 a with potassium iodide or sodium iodide (?). 
b. Use the apparatus in Fig. 19. Place in the flask a mix- 
ture of finely powdered iodine (20 g.) and red phosphorus 
(1 g.) intimately mixed in the mortar. Charge the U-tubes as 
in 54 b. Place a little water in the dropping-funnel (or substi- 
tute, 44 6), warm the materials in the flask very slightly (Ex- 
treme caution!] by waving the Bunsen flame once or twice 
under the vessel, and allow the water to drop very slowly upon 
them (?). After the air has all been expelled, and the solution 
in the second U-tube has become sufficiently concentrated, 
remove the second U-tube. Test the issuing gas with moist 
air (?) and with ammonia (?) as in 54 b. Hold in the gas a 
piece of filter paper dipped in starch emulsion alone (?). Ex- 
plain. Reserve the contents of the second U-tube for use in 
60 a. 
59. Preparation of Hydriodic Acid [Hood]. Place 5 g. of 
powdered iodine with 50 c.c. of water in a small flask provided 
with a cork and an L-tube extending to the bottom. Pass §591 
BROMINE, IODINE, FLUORINE 
57 
hydrogen sulphide from a Kipp's generator, or from the labora- 
tory supply, through the mixture, loosening the cork once or 
twice at first to permit the air to be displaced by the gas, until 
the iodine is all gone and the solution no longer becomes brown 
on being shaken. Agitate constantly to hasten the process. 
Describe what happens. Towards the end of the operation, 
why does the iodine dissolve [R 279] (?) and why does the whole 
action then proceed much more rapidly? Warm and filter the 
solution. 
Obtain a distilling-flask and condenser [Storeroom] and distil 
the filtrate fractionally (Fig. 20), collecting first the part that 
comes over at 100°, then the parts boiling between 100-103°, 
Fig. 20 
103-106°, and so forth. Use a very small flame, and be careful 
not to allow it to reach the walls of the flask above the liquid, 
or breakage will take place. A large flame may not only crack 
the flask, but may also cause the thermometer to show a higher 
temperature than it could acquire from the vapor alone. Stop 
when the liquid is nearly all distilled off. Note the highest 
temperature reached. Pour the residue into a test-tube and 
keep the series for use in 60 b. 
What substance causes the color of the higher fractions and 58 
BROMINE, IODINE, FLUORINE 
[§62 
of the residue? Confirm your conclusion by a suitable test 
(57). How is this colored substance formed? 
60. Properties of Hydriodic Acid. 
a. If 58 b was done, carry out the same experiments with 
the solution as were made with the solution of hydrobromic 
acid in 55 (?). Compare the results with those of 55 (?). 
b. If 59 was done, add silver nitrate solution to each of the 
fractions above 100° obtained in 59, using only a part of the 
liquid in the case of the two with the highest boiling-points. 
At what temperature did the most concentrated solution of 
hydrogen iodide come over? What peculiarity of aqueous 
hydriodic acid does the result indicate? What other solutions 
show the same peculiarity [R 211, 273, 279, 437, 526]? 
Place a piece of zinc in the remainder of one of the higher 
fractions (?). Test the other with litmus paper (?), and then 
add pulverized manganese dioxide, and warm (?). 
61. Hydrogen Fluoride. Cover a square of glass with a 
thin layer of paraffin by warming it very cautiously far above 
a Bunsen flame and rubbing it on one side with solid paraffin. 
Moisten about 3 g. of fluorspar in a leaden dish [Storeroom] 
with concentrated sulphuric acid (do not cover with the acid). 
With the end of a file draw some design upon the paraffin- 
coated side, thus exposing parts of the glass to the action of 
the vapor. Now cover the leaden dish with the glass, paraffin 
side down, and set it in a moderately warm place, but not so 
warm that paraffin may be likely to melt. After half an hour 
or more remove the glass cover, warm, and wipe off the melted 
paraffin with filter paper (?). Write equations representing 
the action, and state what becomes of each of the constituents 
of the glass [R 283, 632]. Try the test of a rod dipped in am- 
monium hydroxide and held over the contents of the lead 
dish (?). Does the gas fume with moist air? What sub- 
stances, beside fluorspar, would serve the purpose of this ex- 
periment? Why could not hydrochloric acid or nitric acid be 
substituted here for sulphuric acid? What acid that we have 
employed could be used here? 
How may fluorine be liberated from a fluoride? Why can 
it not be isolated from fluorides by the action of oxidizing 
agents, as was the case with the other halogens? 
62. Reducing Action of Hydrogen Iodide and Hydrogen 
Bromide [Hood]. In connection with this experiment, it must §63] 
BROMINE, IODINE, FLUORINE 
59 
be kept in mind that an odor similar to that of rotten eggs 
shows the presence of hydrogen sulphide (59), and an odor of 
burning sulphur the presence of sulphur dioxide (15 a). 
a. Pulverize finely about 1 g. of potassium iodide, place it 
in a test-tube, and moisten with one or two drops of concen- 
trated sulphuric acid (?). If too much acid has been taken, 
start again. Warm gently. Investigate the result, which 
furnishes a mixture of gases, as follows: 
a. Breathe across the mouth of the test-tube to ascertain 
the effect of the gas on moist air (?). What gases previously 
made showed the same behavior? What do you infer in this 
case? To confirm this conclusion, lower a glass rod dipped in 
ammonium hydroxide into the test-tube (?). 
/3. Is any characteristically colored vapor (?) mixed with 
the gas recognized in a? Can you observe any other property 
which identifies the substance? By what kind of chemical 
action could this colored substance be formed from the product 
identified in a? By what name is such a reaction known? 
Was there any corresponding product formed when sulphuric 
acid acted upon a chloride? 
7. Can you recognize still another (gaseous) product by its 
odor? 
The work in a and and 7 leads to the recognition of three 
gaseous or vaporous products. Do not attempt to put all of 
these in one equation. Construct an equation for the forma- 
tion from the original materials of the gas recognized in a 
(primary action), and make a separate equation for the forma- 
tion of the other two products from the interaction of sulphuric 
acid with the gas recognized in a (secondary action). What 
two properties of sulphuric acid and what property of hydrogen 
iodide are illustrated by this set of observations? 
In case the above directions are not followed implicitly, and 
large pieces of potassium iodide are taken, or too much sul- 
phuric acid is used, still another gas (sulphur dioxide) may be 
formed along with or instead of one of the above, and, in addi- 
tion, a sublimate of free sulphur may be seen on the tube 
[R 277]. 
b. Repeat the work in a, using powdered potassium bromide 
instead of the iodide, and answer the same questions. 
63. Identification of Halogen Compounds. Imagine that 
there are given to you four white substances, and that you 60 
BROMINE, IODINE, FLUORINE 
[§ 63 
know them to be the fluoride, chloride, bromide, and iodide of 
some metal. State what experiments you would make, and what 
reasoning you would use, in order positively to identify the 
halogen constituents of each. In two of these cases, two dif- 
ferent actions have been encountered in this chapter and might 
be used, and in the other two cases only one. Still another kind 
of action might readily be thought of [R 120, 275]. Negative 
results, say by showing that one is not a chloride, bromide, or 
iodide, and is therefore a fluoride, must be confirmed by a 
positive experimental test. 
If the four hydrogen halides were given you in gaseous con- 
dition in four jars, how should you proceed by chemical means 
to identify each? CHAPTER IX. 
RADICALS. DOUBLE DECOMPOSITION. HYDROGEN PEROXIDE. 
64. Radicals and Double Decomposition. 
a. To a few drops of potassium chloride solution add silver 
nitrate solution (?). What kind of chemical interaction do 
salts usually show in solution [R 324. See Note 4, p. 1]? 
Write the equation for this action. How can we tell whether 
the precipitate is silver chloride, or potassium nitrate, or both? 
Which is it (Appendix IV)? What was the interaction of 
silver nitrate with hydrochloric acid (37 A)? To a few drops 
each of solutions of two other chlorides, such as ferric chloride 
and calcium chloride, add a little silver nitrate solution (?). 
Are these actions reversible [R 324]? Are they complete? 
Why? 
To find out whether all substances containing chlorine give 
silver chloride in this way, try a few drops of potassium chlorate 
solution with the same silver compound (?). State now what 
radical a substance must contain in order that, with silver 
nitrate, it may yield silver chloride (?). 
b. To a few drops of silver sulphate solution add a solution 
of any chloride (?). To find out whether all substances con- 
taining silver yield silver chloride in this way, take a few drops 
of silver nitrate solution in each of two test-tubes. To the 
one portion add some ammonium hydroxide, and so obtain a 
solution of ammonio-silver nitrate Ag(NH3)2NO3. To the 
other add some potassium cyanide solution [Caution! Poison!] 
until the liquid is clear [Note 36, below], and so obtain a solu- 
tion of potassium argenticyanide KAg(CN)2. Now add to 
each of these a solution of sodium chloride (?). Is the silver 
radical present? Do all substances containing silver, when 
mixed with a chloride, give silver chloride? Which compounds 
alone give silver chloride by double decomposition? 
c. Which substances alone will, by addition of mercurous 
nitrate, give mercurous bromide (55 d)? Which substances 
alone will, by addition of silver nitrate, give silver iodide (60 a 
61 62 
DOUBLE DECOMPOSITION 
[§65 
and 6)? Which substances alone will, by addition of an acid, 
give hydrogen chloride (36)? Name the classes of substances 
which are composed of radicals, and commonly interact by 
double decomposition. 
Note 36. - An insoluble body will not dissolve as such merely 
because of the addition of an excess of the precipitant, or even 
because of the introduction of a different reagent. When an in- 
soluble body appears to go into solution, the phenomenon indi- 
cates that the substance added has interacted chemically with the 
insoluble substance and has produced a new substance which is 
soluble in water. 
65. Chemical Equilibrium in Double Decomposition. 
a. When solutions of two substances, each composed of two 
radicals, are mixed, and no precipitate is observed, interaction 
nevertheless occurs. Why was no precipitate observed when 
solutions of silver nitrate and potassium chlorate (64 a) were 
mixed? To answer this question, write the equation for the 
double decomposition which might occur, and consider the 
solubilities of the products (Appendix IV). A similar case 
where the presence of the products is easily shown may now 
be studied (see 6). 
b. Place 10 c.c. of water in each of two test-tubes, add to 
one a single drop of ammonium thiocyanate solution, and to 
the other a single drop of ferric chloride solution. Now mix 
the solutions (?). Write the equation for the action which 
may be assumed to have occurred. Is there any evidence that 
interaction has taken place? Which of the four is the colored 
substance? Use the mixture for c. 
c. When no precipitate is formed, is an action like the above 
(a or 6) complete? To answer this question, divide the mix- 
ture from b equally between four test-tubes. Keep one for 
reference. To the second add one drop of ferric chloride solu- 
tion (?), and to the third a drop of ammonium thiocyanate 
solution (?). Interpret the result. Now add to the fourth 
tube a few drops of ammonium chloride solution (?) and explain. 
What other action have we shown to be reversible (33)? All 
double decompositions of substances composed of radicals are 
reversible, like these two. They are also often far from com- 
plete, when, as in the present instance, precipitation does not 
occur. Why does precipitation tend to make the action more 
nearly complete? §66] 
DOUBLE DECOMPOSITION 
63 
66. Another Incomplete Reaction. 
a. Weigh out 1 g. of calcium chloride (fused or gran.) and 
1.2 g. of oxalic acid. Dissolve each, separately, in 10 c.c. of 
water, and heat the solutions to the boiling-point. Add the 
oxalic acid solution to the calcium chloride solution, a little at a 
time, boiling for two minutes and allowing the precipitate to 
settle between the additions. When one drop ceases to pro- 
duce any fresh precipitation in the clear part of the liquid, note 
what proportion of the original oxalic acid solution remains 
unused (?). Add this remainder, thus making sure that there 
is an excess of oxalic acid present, beyond that apparently 
necessary to precipitate all the calcium. 
The radicals are (Ca)(Cl)2 and (H)2(C2O4). Write the equa- 
tion for the action (?). Write the name under the formula 
of each substance (?), and a downward arrow beside that of the 
precipitate (?). 
b. Proceed now to find out whether this reaction is incom- 
plete or practically complete. To do this, shake the mixture 
and pour it all on to a filter. Catch the filtrate in a clean test- 
tube, label it F (use in c). Set a vessel under the funnel, and 
wash the precipitate (calcium oxalate) with water. To do this 
pour water, a little at a time, from a test-tube on to the filter, 
so as to wash every part of it. When the filter has drained, set 
a test-tube under the funnel, puncture the filter-paper with a 
glass rod, and wash the calcium oxalate through into the test- 
tube. 
If the reaction was reversible, the equation, when read back- 
wards, represents a possible chemical action. Name the inter- 
acting substances in the reversed action (?). To the calcium 
oxalate, suspended in water, add the required reagent (?). Was 
the action a reversible one? The conclusion may be confirmed 
as follows: 
c. If this reverse action occurs, it was in operation in the 
original mixture made in a. In that case, all the calcium could 
not have been precipitated, some must be present in the filtrate 
F, and the reaction was incomplete. The reaction may be 
completed by removing (or chemically altering) one product. 
Destroy the hydrochloric acid by adding to the filtrate F ammo- 
nium hydroxide a drop at a time and shaking (?). What does 
the result prove? Was this action more or less nearly complete 
than that in 65? Why? 64 
DOUBLE DECOMPOSITION 
[§67 
67. Peroxides. 
a. Prepare a solution of sodium peroxide by adding 2 g. of 
this salt, a very little at a time, to 100 c.c. of cold water in a 
flask. Shake and cool (why? [R 85]) the mixture in a stream 
of water during the process. While still cooling the solution, 
add to it dilute sulphuric acid a few drops at a time until the 
mixture is acid (test?). What does the liquid now contain 
(65 a)? Divide the mixture into four parts and use them in 
b, c, d, and e. 
b. To one portion, contained in a small test-tube, add finely 
powdered manganese dioxide (?). Test the escaping gas for 
oxygen. What role does the manganese dioxide play here? 
c. Prepare a solution containing free permanganic acid and 
sulphuric acid by adding a large excess of dilute sulphuric 
acid to 5 c.c. of potassium permanganate solution (equation?). 
Add some of this mixture to the second portion (from a). Test 
for oxygen the gas which comes off (?). What variety of chemi- 
cal activity does the hydrogen peroxide show here? 
d. To the third portion add some starch emulsion containing 
a drop of potassium iodide solution (?). In writing the equa- 
tion for this action remember that the solution of hydrogen 
peroxide from a contained excess of sulphuric acid, which will 
interact with the potassium iodide (?). The product of this 
action then interacts with the hydrogen peroxide. What vari- 
ety of chemical activity does the hydrogen peroxide show here? 
e. Cut a long, narrow strip of filter paper, and moisten it 
with lead nitrate solution. Pour 1 c.c. of ammonium sulphide 
solution into a test-tube, and hang the strip of paper in the test- 
tube until it becomes black. What substance is formed? 
Now, dip the paper in the fourth portion of the solution from a 
(?). What practical application of hydrogen peroxide is here 
illustrated? 
f. To the fourth portion add 5 c.c. of ether (object of this 
[R 319]?) and shake, and then add one drop and no more of 
potassium dichromate solution and shake again (?). This is 
one of the most characteristic and delicate tests for hydrogen 
peroxide. 
State what substance here interacts with the hydrogen per- 
oxide and how it is formed [R 319]. Make no equation. 
g. Suspend lead oxide, barium dioxide, and pulverized 
manganese dioxide, separately, in water, add dilute sulphuric §671 
DOUBLE DECOMPOSITION 
65 
acid and shake for some time, cooling as in a. Filter, and apply 
to each filtrate the test described in / (?). 
What are the differences in behavior and constitution between 
a true peroxide (peroxidate) and those oxides which are some- 
times called peroxides [R 321]? 
h. What are the radicals of: Bromic acid, potassium chlorate, 
hypochlorous acid, bleaching powder, sodium peroxide, potas- 
sium permanganate. CHAPTER X. 
IONIZATION AND INTERACTIONS OF ACIDS, BASES, AND 
SALTS. 
68. Ionization. Name the four distinct methods by which 
we may ascertain experimentally whether a substance is ion- 
ized in solution or not, and learn the extent of the ionization 
[R 333, 336, 337, 361]. Define the term ion- 
ization, first in theoretical terms (?), and second 
in terms of the experimental evidence (?). 
The degrees to which aqueous solutions of 
many substances are ionized are given in Ap- 
pendix VI. Constant reference to this will be 
necessary in interpreting the observations in 
this and succeeding chapters. 
The experiments of this paragraph may be 
postponed until after the work in 69 or 70 has 
been done, if a set of the apparatus is not avail- 
able at this moment. 
Obtain [Storeroom] an electrolytic cell * (Fig. 
21). Half fill the cell with the substances named 
below in turn. See very particularly that the electrodes in the 
cell are not touching one another. Connect with the terminals 
on the lamp board f (Fig. 22b), and note whether the lamp 
Fig. 21 
* Each cell consists of a glass, flat-bottomed, specimen tube (about 
75 X 22 mm.) fitted with a two-hole rubber stopper in which a ver- 
tical groove has been cut to permit the escape of gases. The electrodes 
are pieces of tin about 10 cm. long. 
f A storage battery of three lead cells or five Edison cells in series may 
be used, but is always in danger of being ruined by short-circuiting 
through carelessness. Protection by means of a fuse leads to continual 
interruptions of the work. Where direct current is employed in the light- 
ing system, the best plan is to use the circuit through two resistances of 
such ratio to each other as to give the desired potential by the drop over 
one of them. Thus, if we place a 20-ohm, and a 3.5 ohm resistance on a 
110 volt circuit (Fig. 22a, diagrammatic), the potential drop over the 
lower resistance will be about 16.5 volts. If these resistances be of 
sufficient carrying capacity (say, 5 amperes), then four different current 
outlets may be provided - each one with plenty of current for one of 
the electrolytic cells previously described. Each of these outlets is in 
66 S 68] 
ACIDS, BASES, AND SALTS 
67 
glows or not (?). The cell is in series with the lamp and, if 
the lamp glows, the solution is a conductor. If it does not 
glow, the solution is a non-conductor. When the same experi- 
ment has been shown in the class-room, the 
result may be recorded here and the ex- 
periment omitted. Wash the cell and elec- 
trodes and wipe the latter very carefully 
after each trial. 
The following eight substances, or solu- 
tions, show the behavior typical of the 
classes of materials to which each example 
belongs. After giving the result in your 
notes, name the class which is illustrated 
in each case. 
If the substance is a conductor, what 
conclusion is to be drawn in regard to the 
condition of the dissolved body? In each 
such case, write an equation showing the 
materials present in the solution, and write 
the name [R 356] under the formula of each 
substance (?). 
Fig. 22a 
Fig. 22b 
a. Dry, crystallized sodium chloride (?). 
b. Distilled water (?). 
c. Aqueous solution of sodium chloride (?). 
d. Diluted aqueous solution of sodium hydroxide (?). 
e. Diluted aqueous solution of hydrogen chloride (?). 
series with a small battery lamp, used as an indicator of the flow of cur- 
rent through the cell (Fig. 22b). 
Where alternating current only is available, a small rotary transformer, 
now commonly employed for charging automobile batteries, may be used. 68 
ACIDS, BASES, AND SALTS 
[§ 70 
f. Aqueous solution of sugar (?). Now, dry the cell by wash- 
ing first with alcohol and then with ether. 
g. Toluene in the dried cell (?). 
h. Hydrogen chloride dissolved in dry toluene (?). What 
difference between water and toluene do e and h bring to light? 
Keep this solution corked up in a dry test-tube for use in 72 d. 
69. Ionic Materials. 
a. Give the names and symbols (not forgetting the charges) 
of the three chief physical components, i.e., distinct substances 
(in addition to water), present in the aqueous solutions of sodium 
chloride, hydrogen chloride, and sodium hydroxide [R 356] (?). 
In these solutions there are still other physical components pres- 
ent in small amounts - which are these in each of the cases 
just mentioned [R 399]? 
b. Give a concise comparative statement of the specific physi- 
cal properties (such as color, molecular weight, solubility, 
behavior towards electrically charged bodies, physical state) of 
the ionic and the free forms of sodium, hydrogen, and chlorine 
(?). 
70. Relations of the Molecular Substance to its Constit- 
uent Ionic Substances (in Equilibrium). The ions of an ion- 
ogen and the remaining molecules are in chemical equilibrium 
[R 358]. What changes take place, respectively, when the 
solution is concentrated by evaporation and when it is diluted, 
as in a, below [R 377, 378]? Can the proportion of mole- 
cules be increased otherwise than by concentrating the solu- 
tion (see b, below) [R 379]? With substances like sodium 
chloride and hydrogen chloride these changes cannot be per- 
ceived by the eye (why?). In the following instances (a and 
5) the ionic and molecular substances are both perceptible to 
the eye, and their relations as described above may, therefore, 
be studied very easily. 
a. Examine a solution of potassium bromide. What is the 
color of bromide-ion? Take a minute amount (say 0.2 g.) of 
cupric bromide in a dry test-tube. Add two drops of water and 
agitate for some time (?). Then add more water, a drop or 
two at a time, agitating vigorously, and giving the substance 
time to dissolve, if it can, after each addition. Continue the 
addition of water cautiously until the substance has all dis- 
solved, and afterward until the change in color is complete, 
and then stop. What is the color of the molecules of cupric §70] 
ACIDS, BASES, AND SALTS 
69 
bromide? What is the color of cupric-ion? Compare the 
color with that of cupric sulphate solution (?) and explain. 
Formulate the change which has been witnessed. 
b. Now take a fresh portion of cupric bromide and repeat 
the experiment as in a, stopping the addition of water at the 
green stage. Divide the mixture into two parts. To one add 
2-3 g. of solid potassium bromide and shake vigorously (?). 
To the other portion add 4-5 g. of solid cupric chloride (?). 
Interpret the results. 
The converse case, in which one of the ions is removed and 
the dissociation is promoted, is discussed in d. 
c. Many ionic substances are colored, although the color 
does not always differ markedly from that of the molecules. 
Examine the following solutions, make a list of the ionic sub- 
stances contained in them, with their formulae and charges, and 
note the color of each kind of ions: cobalt chloride, potassium 
permanganate, potassium dichromate, chrome-alum (this last 
solution freshly made by dissolving the solid). 
d. Just as the union of ions to form molecules may be pro- 
moted by addition of a substance yielding a common ion (? 70 6), 
so the reverse of this, namely, the dissociation of molecules 
into ions, may be promoted by the removal of one of the ionic 
materials. The removal of ions may be accomplished in several 
ways [R 382, 387]: 
(1) By union of the ion with some other ion, when the mole- 
cules thus formed are insoluble. This case will be illustrated 
next (see 71). 
(2) By union of the ion with some other ion, when the mole- 
cules thus formed, although soluble, are very little dissociated 
by water (see 73, 83, 92 d). 
(3) By discharge of the ion and liberation of its material, 
through transfer of the charge to another substance (see 
75). 
(4) By union of the ion with some other material to form a 
compound ion, illustrated in 64 b. 
(5) By decomposition of the ion, as in 67 b, c. 
(6) By the mere change in the valence (amount of the charge) 
of an ion, for this converts it into another substance of the 
same material composition (see 181^, 192 6, 193 d). 
(7) By discharge of the ion and liberation of its material 
through electrolysis. This was illustrated in 68 c, d, e. 70 
ACIDS, BASES, AND SALTS 
[§ 71 
71. Precipitation on Mixing lonogens. 
a. Place 3-4 c.c. of silver nitrate solution in a test-tube 
and dilute with water. Add potassium chloride solution cau- 
tiously and agitate continuously, until no further precipitation 
occurs (?). Filter, concentrate the filtrate by evaporation, 
and pour it into a watch-glass to crystallize (?). Two salts 
are formed, one by precipitation and one by evaporation (see 
Fig. 23). 
Formulate the action (Fig. 23). In doing this, show the 
Fig- 23 
three main physical components of each of the original solu- 
tions and the relations of these components (in equilibrium) to 
one another in each case. Show also the molecular products 
formed when the solutions are mixed. Assuming that the solu- 
tions are approximately decinormal [R 182], ascertain the pro- 
portions in which the original components are present before 
mixing (Appendix VI). Learn also to what extent the molecular 
products will be formed by union of the ions (Appendix VI), 
and, in the case of an insoluble substance, how complete 
will be the precipitation (Appendix IV). On the basis of 
this complete information, explain in detail, and one by one, 
in what way, and to what extent, each of the six original com- 
ponents is affected by the results of mixing (?). 
Name the components of the filtrate and explain how each 
is affected by the evaporation and crystallization. 
How does the formation of the precipitate of silver chloride 
illustrate 70 d (1)? Upon what factor does the completeness 
of the change depend? Is, or is not, silver chloride a highly 
ionized substance [R 383]? 
Aside from double decompositions, what means have we for 
learning of what radicals a salt (like silver nitrate) is com- 
posed? 
b. To a little cupric sulphate solution in a test-tube add §73] 
ACIDS, BASES, AND SALTS 
71 
sodium hydroxide solution (?). Exactly as in 71 a (second 
par.), formulate, study, and explain the whole action. How 
does this illustrate (1) of 70 d? 
To what classes of ionogens do the four molecular substances, 
respectively, belong? 
c. To a little cupric sulphate solution add a little dilute 
hydrochloric acid (?). In what respects does the result differ 
from those in a and b, and why? Can any acids be prepared 
by precipitation, and if so, which [R 634, 639]? 
In future, formulate all ionic actions in the way indicated in a. 
72. Bases and Acids: Hydroxide-ion and Hydrogen-ion: 
Indicators. 
a. Examine distilled water in respect to (a) taste, (b) be- 
havior with litmus, (c) conductivity (done already, 68 b). 
b. Dissolve a small piece of sodium hydroxide in water and 
examine the solution in respect to (a) taste, by diluting a 
little and tasting one drop, (b) behavior with litmus, (c) be- 
havior with phenolphthalein, (d) conductivity (see 68 d). These 
properties belong to aqueous solutions of all bases. Aside from 
the water, what component alone is common to all such solu- 
tions and has the above properties? 
c. Examine an aqueous solution of hydrochloric acid in 
respect to (a) taste, (b) behavior toward litmus, (c) behavior 
with phenolphthalein, (d) conductivity (see 68 e), action on a 
piece of marble, (e) action on an iron nail (clean this with the 
file before use). These properties are shown by all aqueous 
solutions of acids. Aside from the water, what component 
alone is common to all such solutions and has these proper- 
ties? 
d. Take the solution of hydrogen chloride in toluene (68A) 
and examine it in respect to (a) conductivity (see 68 A), (b) 
action on a piece of marble, dried in advance by heating in a 
dry porcelain dish for a few moments, (c) action on an iron 
nail (clean as before). Be sure that perfectly dry vessels are 
used in these experiments. What substance identified in c is 
absent from this solution? What difference between water 
and toluene, as solvents, does this result indicate? In what 
three other respects would the two solutions of hydrogen chlo- 
ride be found to differ? 
73. Ionic Chemical Changes: I. Union and Disunion of 
Ions: Neutralization (Union of H+and OH-). (Two students 72 
ACIDS, BASES, AND SALTS 
[§ 73 
working together.) A considerable chemical change may occur 
not only in precipitation (see 71), but also when ions unite to 
form a substance which, although soluble, is very little ionized 
by water. Such changes are illustrated in 73 and 74. 
Weigh out 5 g. (laboratory scales) of potassium hydroxide, 
dissolve it in 50 c.c. of distilled water, and pour the clear solu- 
tion into a burette (Fig. 4, p. 8). Measure 10 c.c. of con- 
centrated hydrochloric acid in the graduated cylinder, mix it 
in a small beaker with 50 c.c. of distilled water, and pour this 
into a second burette. Now, into a small beaker or flask run 
15 c.c. of the acid solution from the second burette, and then 
add to it two drops of phenolphthalein solution. Place the 
vessel under the first burette, read the level of the liquid in 
the burette, and allow the alkali to run into the acid drop by 
drop, stirring constantly, until the last drop confers the faintest 
perceptible pink tinge on the whole solution. If you do not at 
first succeed in stopping at the right point, repeat the experi- 
ment. Note the volume of alkali used. Concentrate the solu- 
tion on the sand bath until a drop deposits crystals on cooling, 
and then remove the dish from the sand bath promptly and 
set it aside. 
When sufficient crystals have appeared, dry them with filter 
paper and examine with respect to (a) form, (b) taste, (c) 
exposure to moist air, (d) action of a solution on litmus, (e) 
conductivity of aqueous solution (done already, 68 c). Con- 
struct a table comparing the substance in these respects with 
the materials from which it was made. Compare the substance 
with potassium chloride in your desk or on the side-shelf. How 
should you determine whether a substance obtained in this way 
contained "water of crystallization" or not? Make the neces- 
sary experiments (?). Wash out the burettes. 
Following the directions in 71 a (second par.), formulate, 
study, and explain the whole action. Note, however, that there 
is here no insoluble substance. Show how this experiment 
illustrates 70 d (2). 
Express the change involved in every neutralization of highly 
ionized substances by means of the simplest equation [R 387]. 
How may neutralization be defined, in terms of the hypothesis 
of ions? How may it be defined, taking account of all the facts, 
but omitting all reference to ions. 
Calculate the approximate concentration, in terms of a nor- §75j 
ACIDS, BASES, AND SALTS 
73 
mal solution as unity, of the potassium hydroxide solution used 
above (?). From the volumes of alkali and acid used in neutral- 
izing, calculate the concentrations of the diluted hydrochloric 
acid (?), and of the concentrated acid employed to make it (?), 
expressing the concentrations in terms of a normal solution. 
Calculate the number of grams of hydrogen chloride per liter in 
the dilute and concentrated acids, respectively (?)., 
74. Neutralization of Slightly Ionized and of Insoluble 
Substances. 
a. Consider the degree of ionization of acetic acid (Appendix 
VI). To neutralize 1 liter of normal acetic acid, would more or 
less alkali be required than to neutralize 1 liter of normal hydro- 
chloric acid? In what way, precisely, would the details of the 
change be different in the case of acetic acid [R 394]? Name 
some of the consequences of this difference [R 396, 397]. 
b. Dilute a few drops of cupric sulphate solution with water 
and add excess of sodium hydroxide solution (?). Fit a filter 
paper properly into a funnel (Fig. 6, p. 11). Filter the mix- 
ture, and wash the precipitate (?) repeatedly with distilled 
water to remove soluble substances. Now place a clean test- 
tube below the funnel, perforate the bottom of the filter paper, 
and wash the precipitate through into the test-tube by means 
of a stream of water from the wash-bottle. To the suspended 
cupric hydroxide, cautiously add dilute hydrochloric acid in 
amount just sufficient to give a clear liquid. Concentrate the 
liquid on the sand bath until a drop, removed to a watch-glass, 
shows signs of crystallizing when cold. Then remove the dish 
promptly from the sand bath and allow it to cool. Examine the 
crystals (?). 
Formulate this action as in 71 a, taking account, however, of 
the fact that one of the interacting substances is an "insoluble" 
solid [R 419]. Describe in detail the stages through which the 
final production of solid cupric chloride is accomplished. 
To what class of ionic chemical changes [R 402] does the 
foregoing action belong? Answer the same question in regard 
to the precipitations of salts in 71. 
75. Ionic Chemical Changes: II. Displacement. 
a. Place several pieces of granulated zinc in a dilute solution 
of cupric sulphate and set aside until the change is complete 
(test?). Occasional agitation will hasten the change (why?). 
Filter. What is the precipitate [R 403]? 74 
ACIDS, BASES, AND SALTS 
[§ 76 
Before examining the filtrate, take a few drops of cupric sul- 
phate solution and a like amount of zinc sulphate solution in two 
test-tubes. Dilute each solution with water, and add to each 
ammonium sulphide solution (?). What is the precipitate in 
each case, and what ions are required to form it? 
To the filtrate from the first part of this experiment add 
ammonium sulphide solution (?). What ions were present in 
the filtrate? What changes did the zinc and the cupric-ion, 
respectively, undergo in the first part of the experiment? For- 
mulate this change in an equation. In the course of this ex- 
periment, what becomes of the molecular cupric sulphate 
(70 d (3))? 
What substances could have been substituted for the cupric 
sulphate without affecting the result, so far as the consumption 
of zinc and the precipitation of copper were concerned? What 
substances, beside zinc, would have precipitated copper [R 
404]? What other elements, beside copper, are displaced by 
zinc? 
Which one of the elements displaced by zinc did we prepare in 
quantity by an action like the present (20). Formulate this 
action in terms of ions (?). What were the products of the action 
of zinc upon concentrated sulphuric acid (18 d)? What is the 
chief component of this form of the acid (Appendix VI)? If this 
component interacted with the zinc, to what class of chemical 
changes did this action belong? 
b. Formulate the actions in 18 a in terms of ions. Explain 
the differences in activity of the various metals [R 404]. 
c. Examine your notes on Chap. VIII. Formulate the fol- 
lowing actions in terms of ions: 
Free chlorine and bromide-ion (53 b and 55 g). 
Free chlorine and iodide-ion (57 c and 60 a). 
Free bromine and iodide-ion (57 d). 
Free iodine and sulphide-ion (59). 
Arrange these four elements in a series similar to the electro- 
motive series of the metals (Appendix VII). Where should you 
place fluorine in this series [R 281]? Indicate the approximate 
position of oxygen [R 279, 281]? 
76. Ionic Chemical Changes: III, IV, V. In addition to 
union or disunion of ions (I), and displacement (II), there are 
three other ways in which ions may undergo chemical change. 
Electrolysis (III) was illustrated in 68. §77] 
ACIDS, BASES, AND SALTS 
75 
Formation or decomposition of a compound ion (IV) was illus- 
trated in 39 a, b, in 64 b, and in 67 c (?). 
Change in charge on an ion (V) was illustrated in 39 a (?). 
Define each of these three classes of ionic chemical change and 
formulate the illustrations anew so as to show how the actions 
cited belong to the class illustrated (?). 
Re-examine the seven ways in which ionic substances are 
removed, and dissociation of the parent molecules is promoted 
(70 d), and indicate that one of the five classes of ionic change 
to which each of the seven belongs. 
77. Non-Ionic Actions. In previous classroom and labora- 
tory experiments we have observed the formation of ionogens 
in other ways than those illustrated in this chapter. These 
ways are non-ionic, or not distinctly ionic. Give illustrations 
of such of these ways as you recall: acids, two ways; bases, one 
way; salts, four ways; together with the reference numbers of 
the laboratory experiments in which they occur. CHAPTER XI. 
SULPHUR. 
78. Sulphur. 
a. Place about 0.5 c.c. of powdered roll sulphur in a dry test- 
tube, add 2 c.c. of carbon disulphide and shake (?). Pour the 
solution into a watch-glass and set it to evaporate [Hood] away 
from all flames. 
Examine the crystals with the eye and with a lens and make 
a drawing of two of them (?). Are they brittle or soft? Color? 
Are they transparent? After 24 hours (or more), are they still 
transparent? 
b. Fold a filter-paper as if for filtration, and put water in a 
large beaker. Half fill a dry test-tube with roll sulphur. Hold 
the test-tube with a clamp and melt the sulphur. Heat gently, 
turning the tube in the flame. Dark brown patches show over- 
heating at these points - melted sulphur is pale straw-color. 
Hold the filter paper by the edge at the three-fold side and 
pour the melted sulphur into it. Watch the crystals grow. 
When crystals have formed at the surface and reached the center, 
pour the remaining liquid sulphur promptly into the beaker of 
water, and open up the paper immediately. 
Examine the crystals with the eye and with the lens and 
make a drawing of two of them (?). Are they brittle or soft? 
Color? Are they transparent? After 24 hours (or more), are 
they still transparent? If not, into what form of sulphur have 
they turned? Explain the change in appearance (?). 
Examine the part that was poured into water. Is it brittle 
or soft? Dry a small piece of it and shake it with 1 c.c. of carbon 
disulphide (?). 
c. In the same test-tube place 10 g. of roll sulphur and melt. 
Continue heating until the sulphur boils and note the changes 
in color and fluidity which occur (?). If the vapor catches fire, 
allow it to burn. Pour the boiling sulphur into a large beaker 
of water, moving the tube about. 
Examine the product. Is it crystalline? Is it brittle or 
76 §80] 
SULPHUR 
77 
soft? Is it transparent? After 24 hours (or more) is it still 
transparent? After 24 hours (or more), dry a part of it and 
shake with a little carbon disulphide (?). To find out whether 
any has dissolved, pour part of the liquid on to a filter, catch a 
few drops of the filtrate on a watch-glass, and allow them to 
evaporate [Hood] away from flames (?). 
What is the insoluble material? Color? Examine with a 
lens (?). Is it crystalline? 
What would have been the result if the boiling sulphur had 
been allowed to cool slowly, instead of being chilled in water? 
79. Sulphides of Metals. 
a. Place about 2 c.c. of roll sulphur in a dry test-tube and 
fasten the tube upright in the clamp on the stand. Boil the 
sulphur and then drop into the tube a strip of copper foil (?). 
Does the temperature of the copper change noticeably? Was 
it heated thus by the flame, the sulphur vapor, or what? 
Remove the strip of copper and describe thg properties of the 
product (?). Name it (?) and write the equation (?). 
b. Mix thoroughly in the mortar 1 c.c. of iron powder with 
1.5 c.c. of powdered roll sulphur. Place the mixture in a test- 
tube and clamp the latter on the stand. Heat the lower part of 
the material and, when the reaction begins, withdraw the flame. 
Was the temperature at any time higher than that which the 
flame could have produced? What was the source of the heat? 
Describe the product when cold (?). Name it (?), and write 
the equation (?). Keep it for use in 80 a. 
c. Recall and record here a case of the union of sulphur with 
a metal which was observed previously (9 a). Under the same 
conditions (pressure, temperature, contact), does mercury com- 
bine more or less readily with sulphur than with oxygen? Give 
reasons for your answer (?). 
Does sulphur appear to have about the same activity as has 
oxygen, or much more, or much less? 
80. Hydrogen Sulphide [Hood]. 
a. Place about 1 g. of ferrous sulphide in a test-tube and add 
a little dilute hydrochloric acid (?). Note the odor of the gas, 
and apply to it a strip of filter paper dipped in lead nitrate 
solution [R 783] (?). 
b. Using ferrous sulphide and hydrochloric acid, generate 
hydrogen sulphide, using either the apparatus in Fig. 11 (p. 25) 
or a special generator. Connect with the exit tube a glass 78 
SULPHUR 
[§ 81 
nozzle. When the air has been displaced, set fire to the gas. De- 
scribe the color of the flame. Hold a porcelain dish in the middle 
of the flame for a few moments (?). What substance is deposited, 
and must, therefore, exist uncombined in the interior of the 
flame? What other substance does this justify us in assuming 
to be liberated in the same region? What do these facts indicate 
regarding the stability of the gas when heated, and the difficulty, 
therefore, of making the compound by the direct union of its 
elements? What are the products of the complete combustion 
of the gas, and in what two stages does this combustion take 
place? Make equations showing both stages. 
81. Properties of Aqueous Hydrogen Sulphide: I [Hood]. 
a. Take about 15 c.c. of water in a carefully cleaned test- 
tube and, using a clean piece of glass tubing to defiver the gas, 
saturate (test? Note 37, below) it with hydrogen sulphide. Test 
the solution with litmus paper [R 417] (?). Pom' one-third or 
less of the solution into another test-tube and boil this portion 
vigorously, noting from time to time the odor of the vapor (?). 
Can this gas be driven off completely by boiling? Does hydro- 
gen chloride solution behave in the same way or differently 
[R 211]? 
b. Divide the remainder of the solution into two parts and 
add 2-3 g. of iron dust (pulverized iron) to one of them. Shake 
vigorously and then allow the mixture to stand (?). After a 
few minutes collect the insoluble matter upon a filter and wash 
until it no longer smells of hydrogen sulphide. Transfer the 
precipitate to a test-tube by puncturing the paper and washing 
through. Add dilute hydrochloric acid to the product and 
note the odor (?). What substance must have been present 
in the precipitate, and how was it formed? Account for the 
extreme slowness of the action of iron upon the solution of 
hydrogen sulphide [R 417] (?). 
c. Allow the third portion of the solution made in a to stand 
for some days exposed to the air (?). Explain the turbidity (?). 
d. If 59 was performed, record here the action which took 
place. If 59 was not performed, place a single crystal of iodine 
in 5 c.c. of water and saturate (test? Note 37, below) the liquid 
with hydrogen sulphide [R 278] (?). 
What ionic substance is shown by the first part of 81a and 
by 81 b to be present in the solution of hydrogen sulphide [R 417]? 
Explain the actions in c and d in terms of ions. §82] 
SULPHUR 
79 
e. To 2-3 c.c. of potassium dichromate solution add dilute 
sulphuric acid in large excess (?). What change may be 
assumed to have taken place? Now saturate (test? Note 37, 
below) the mixture with hydrogen sulphide (?). What are the 
colors of the solution and of the precipitate, respectively? 
Show that two kinds of ionic chemical change are here illus- 
trated (?). 
f. Take 2-3 c.c. of potassium permanganate solution and 
treat exactly as in e (?). Answer the same questions (?). What 
chemical property of hydrogen sulphide is illustrated in e and f? 
Note 37. - To learn whether a liquid is saturated with a 
gas, withdraw the delivery tube while the gas is issuing, cover the 
mouth of the vessel quickly with the thumb or the palm of the 
hand in such a way that the gas above the liquid has no time to 
escape (why?), and shake vigorously. If the thumb now adheres 
to the mouth of the vessel, the liquid is not yet saturated (why?). 
If the liquid is saturated, what will be the pressure of the gas over 
it after shaking [R 188]? If air is allowed to displace the gas over 
the saturated Equid, what effect will be observed on shaking as 
described above, and why? 
82. Properties of Aqueous Hydrogen Sulphide: II. Sul- 
phides [Hood]. 
a. What was the reaction of aqueous hydrogen sulphide 
towards litmus (81 a)? What ionic substances are present? 
b. Take about 6 c.c. of sodium hydroxide solution and satu- 
rate (test? Note 37) it with hydrogen sulphide (?). Use in c, d, 
e, and /. How should you proceed to prepare neutral (normal) 
sodium sulphide (solid)? 
c. To a few drops of the solution prepared in b add dilute 
hydrochloric acid (?) (see 83 6). 
d. To a few drops add some bromine-water (?). 
e. To a larger portion of the same solution add a little pow- 
dered roll sulphur and shake from time to time. Is sulphur 
soluble in water? What is here to be inferred [Note 36, p. 62]? 
When the solution has become very yellow (?) in color, filter. 
Acidify the filtrate with dilute hydrochloric acid (i.e., add 
more than an equivalent amount of the acid) (?). Recall an 
experiment with iodine which resembles the first part of this 
experiment with sulphur (?). 
f. Allow the remainder of the solution from b to remain 
exposed to the air for several days (?). When a change in 80 
SULPHUR 
[§83 
color has occurred, add dilute hydrochloric acid in excess (?). 
Explain. 
g. Take five clean test-tubes and obtain 2-3 c.c. of the solu- 
tion of each of the following substances. Dilute each specimen 
with 10-20 c.c. of water and saturate (test?) with hydrogen 
sulphide: (a) Cupric sulphate (?), (b) Lead nitrate (?), (c) Cad- 
mium sulphate (?), (d) Ferrous sulphate (make a solution of 
ferrous-ammonium sulphate [R 894] and use it for this [Note 38, 
below]), (e) Zinc acetate (?). 
Explain the precipitation in terms of ions. 
Pour away a part of the contents of each test-tube, add a 
large excess of dilute hydrochloric acid, and shake (?). Explain 
the results. Divide the metallic sulphides obtained in this 
experiment into two classes, and characterize those classes. 
What property of hydrogen sulphide has been illustrated in 
a, b, and g? 
Note 38. - Ferrous-ammonium sulphate [R 894] is preferred to 
ferrous sulphate because it becomes less rapidly impure through 
oxidation by the air. In making equations, disregard the ammo- 
nium sulphate. 
83. Ionic Chemical Changes: Formation of an Inactive 
Acid. 
a. To 2-3 c.c. of sodium acetate solution add an equivalent 
amount of dilute sulphuric acid, and warm gently. One product 
may be recognized by its odor (?). 
Formulate, study, and explain this action according to the 
directions in 71a (second par.). Write a simple equation ex- 
pressing the chief change which occurs. 
b. Consider the action between sodium-hydrogen sulphide 
and hydrochloric acid in 82 c. Formulate, study, and explain 
this action as in 71a (second par.), modifying the scheme of 
formulation to suit the case. Does the escape of the hydrogen 
sulphide assist materially in making the action more nearly 
complete? Does it assist at all? What physical property does 
the escape of the hydrogen sulphide as a gas show this substance 
to possess? 
c. Make a single general statement describing all the cases 
in which, when ionogens are mixed, and no precipitation or 
volatilization occurs, a fairly complete chemical change will 
nevertheless take place (see 72). §85] 
SULPHUR 
81 
Give a list of acids (Appendix VI) which might be formed in 
accordance with the principle embodied in your statement. 
Could any bases be formed in accordance with the same 
principle? Illustrate (Appendix VI). Could any salts be so 
formed (Appendix VI)? 
84. Hydrolysis. 
a. Dissolve a single crystal of sodium sulphide in water, and 
test the solution with litmus paper (?). What ionic substance 
causes this reaction? Which of the two substances taken is 
capable of furnishing this ion? Formulate the interaction of 
the two original substances and explain it [R 418]. 
b. Test with litmus paper the solution of sodium carbon- 
ate (?). Explain (Appendix VI). Of what sorts of radicals 
must a normal salt be composed in order that the solution may 
show an alkaline reaction [R 648]? 
c. Test with litmus paper the solutions of cupric sulphate (?) 
and ferric chloride (?), and account for the result [R 648]. Of 
what sorts of radicals must a normal salt be composed in order 
that the solution may show an acid reaction? Why is sodium 
chloride solution neutral? Define hydrolysis (?). 
85. Sulphur Dioxide. 
a. Touch with a warm platinum wire a bit of sulphur, and 
bring the wire with the adhering sulphur again into the flame. 
Withdraw, and note the color of the flame of the burning 
sulphur and also its odor (?). 
b. Heat in a hard glass test-tube a few particles of iron 
pyrites. What is the sublimate? What gas is evolved? 
c. [Hood] Place a small piece of copper in a test-tube, 
cover it (and no more) with concentrated sulphuric acid, and fix 
the tube in a clamp on the stand. Place the bulb of the ther- 
mometer in the acid, heat continuously, and note the tempera- 
ture at which chemical action becomes apparent (?). 
Remove the thermometer and smell the gas (?). Heat the 
materials with a small flame while proceeding with d. Then 
set the tube aside and, the next day, examine and describe all 
the contents (?). 
d. [Hood] If sulphur dioxide gas is not furnished in the 
laboratory from cylinders of the liquid,* it may be prepared for 
use in 86 or 91 as follows: Fit up a flask (250 c.c.) as in Fig. 15 
* If the gas is not so furnished 85 and 86 should be taken up after 
90. 82 
SULPHUR 
[§86 
(p. 36). If 86 is to be performed, a gas washmg-bottle (r ig. 24) 
will be required to dry the gas, and will contain enough con- 
centrated sulphuric acid to immerse the longer tube to a depth 
of half an inch. Attach the longer tube 
of the bottle by rubber tubing to the 
generating flask. Place about 15 g. of 
sodium bisulphite in the flask. Test 
the apparatus to see that it is air-tight. 
Dilute some concentrated hydrochloric 
acid (1 : 1) and place it in the funnel. 
86. Molecular Weight of Sulphur 
Dioxide [Quant. Hood]. Clean and 
dry a 250 c.c flask and provide it with 
a tightly fitting cork. Weigh the flask 
and cork. This gives the weight of 
the flask filled with air. Now fill it completely with sulphur 
dioxide, by upward displacement of air, cork, and weigh again. 
To insure its being full, repeat this operation till no increase in 
weight occurs. Finally, allow the gas to escape and determine 
its volume. To do this, use the graduated cylinder and fill the 
flask with water up to the cork (?). Observe the temperature 
and pressure of the atmosphere. Correct the volume to 0° and 
760 mm. 
To obtain the weight of the empty flask and its cork, subtract 
from the weight of the vessel filled with air the weight, under 
the observed conditions, of a volume of air equal to the corrected 
volume (1 liter of pure, dry air weighs 1.293 g. under normal 
conditions, or the G.M.V. holds 28.955 g. of air). 
The difference between this weight of the empty flask and 
that of the flask filled with sulphur dioxide is the weight of the 
latter. Using the volume of the flask under normal conditions, 
calculate the weight of the G.M.V. (22.4 1.) and of 11. of sulphur 
dioxide (?). 
Enumerate carefully all the sources of error to which you 
should expect this way of determining the density of a.gas to 
be liable (?). In doing this, consider each detail of the operation 
very critically. 
Temp. . . . ° Barometer (corr.) .... mm. 
Vol. of flask . c.c. 
Vol. of flask, 0° and 760 mm c.c. 
Fig. 24 §87] 
SULPHUR 
83 
Wt. of flask + air g. 
Wt. of air (calc.) g. 
Wt. of flask, empty g. 
Wt. of flask + S02 g. 
Wt. of flask, empty g. 
Wt. of S02 g. 
Wt. of 22.4 1. SO2 g. 
87. Preparation of Sulphuric Acid (Two students working 
together). Obtain a distilling-flask (25 c.c.), rubber connections 
for a safety bottle, a screw-clamp, and a Chapman pump from 
the storeroom. Fit up with your one-liter bottle the apparatus 
as in Fig. 25. Charge the hard glass tube with about 10 g. of 
Fig. 25 
granular pyrite,* and place a small, loose plug of asbestos just 
beyond the pyrite to retain any unburnt sulphur. Put into the 
distilling-flask about 10 c.c. of pure concentrated nitric acid. 
The safety bottle, half filled with water to show the rate at which 
air is being drawn through the apparatus, is attached to the water 
pump. The total air admitted is regulated by the screw-clamp 
* In case very pure pyrite is not available, it is better to depart 
from the common manufacturing process by substituting a boat con- 
taining a little sulphur. 84 
SULPHUR 
[§88 
between the pump and the safety bottle, while the proportions 
which pass over the pyrite and which carry over the nitric acid 
vapor, respectively, are regulated by pinching one of the tubes 
with the finger and thumb. 
First heat the pyrite in a very slow stream of air until the 
sulphur burns. Then warm the nitric acid and, by pinching 
the tube admitting air to the pyrite-burner, divert part of the 
air current so that it may carry over a little of the vapor of 
the acid. Heat the pyrite strongly and continuously. Repeat 
the introduction of air laden with nitric acid at intervals, when- 
ever the disappearance of the red fumes in the bottle shows that 
a further supply is needed. 
After a crust of white crystals (?) has formed in the bottle 
(there may be considerable delay before crystallization starts), 
remove the attachments and blow the gases from the interior 
by means of the air blast. If crystallization fails to begin after 
a reasonable time (note that an interaction even between the 
molecules of gases may be slow, in spite of the completeness of 
the mixing), the cause is either the introduction of too much 
water along with the nitric acid, or the high temperature pro- 
duced by the chemical actions taking place in the bottle. Re- 
moving the attachments and cooling the bottle in a stream of 
water frequently brings crystallization about. 
Add 4-5 c.c. of water and wash down the crystals with it. 
Describe all that happens. If more of the product is required, 
the apparatus may be connected up again and a further supply 
of sulphur dioxide drawn into the bottle, and subsequently 
more nitric acid vapor can be added. Finally any remaining 
crystals may be decomposed by water. 
Filter the liquid in the bottle through a very small filter 
paper into a dish, rinsing the bottle with 2-3 c.c. of water, and 
evaporate on the sand bath [Hood] until the liquid begins to 
fume strongly (?). This will remove any nitric or nitrous acid 
that it may contain. Use the result for 88 a and b. 
88. Properties of Sulphuric Acid. 
a. Dip a match-stick into the liquid from 87 and make 
marks on a sheet of paper. Set both paper and stick in a warm 
place (?). What property of the acid is here observed? 
b. After the acid prepared in 87 is cold, dilute it with 2-3 
volumes of water. Test the solution with litmus paper (?). 
To 2-3 drops of the acid add barium chloride solution (?). To §89] 
SULPHUR 
85 
learn whether the action is easily reversible, add pure hydro- 
chloric acid to the mixture (?). The formation of this precipi- 
tate, and its insolubility, furnish a distinctive test for what 
radical? Which substances contain this radical? What prop- 
erty of sulphuric acid is shown in 6? 
c. Pass a current of hydrogen sulphide through 2-3 c.c. of 
concentrated sulphuric acid. Note the odor (?) and precipi- 
tate (?). What property of sulphuric acid is shown in c? What 
other evidence of this property have we previously observed 
(see 18 d and 62)? 
d. Place a small piece of sulphur in 2-3 c.c. of concentrated 
sulphuric acid, and heat (?). Note the odor (?). 
e. Heat a little charcoal with sulphuric acid and note the 
odor (?). What property of sulphuric acid is shown in d and 
e? Why would not dilute sulphuric acid show this property? 
f. [Hood] Take 2-3 c.c. of concentrated sulphuric acid in a 
test-tube. Suspend a thermometer so that the bulb is com- 
pletely immersed in the acid. Heat the contents of the tube 
by means of a small flame and note the temperature at which 
any effect (?) is observed, and that at which it is conspicuous. 
Relate this temperature to that observed in 85 c. [Caution! 
During the heating remember that, if the tube should crack, 
the hot acid may splash on the clothes and hands and produce 
severe burns. Exercise proper caution. Be careful not to 
wash out this tube until the acid has cooled.] 
89. Sulphuric Acid as a Dibasic Acid. 
a. (Two students working together.) Fill a burette with a 
solution of potassium hydroxide made as in 73. Add 15 c.c. 
of concentrated sulphuric acid slowly to 35 c.c. of water in a 
beaker, and fill another burette with the diluted acid, when cold. 
Ascertain as in 73 what volume of the alkali will neutralize 5 c.c. 
of the acid. Concentrate the mixture by evaporating to about 
10 c.c., remove the dish from the water bath, and allow the 
resulting solution to crystallize. Dry the crystals on filter paper. 
To a second portion of the acid (use no phenolphthalein. 
Why?), twice as great as before, add exactly the same amount 
of the alkali. Evaporate to about 5 c.c. and treat as before. 
Compare the two lots of crystals as regards, (a) form, (b) 
taste, (c) reaction of their solution towards litmus. Con- 
firm by studying the same properties of the pure substances. 
Explain the differences between your own preparations and those 86 
SULPHUR 
[§ 91 
in the laboratory, if any are observed. Explain the differences 
in these three respects between your own preparations and the 
pure ones, if any are observed. Explain, in terms of ions, the 
difference in the reactions of the two products towards litmus. 
Formulate, study, and explain the actions, as in 71 a (second 
par.). Take the components of the original solutions [R 387] 
one by one, and describe what happens to each, (a) during com- 
plete neutralization, (b) during semi-neutralization in the 
second part of the experiment. 
What would be the effect of heating perfectly dry specimens 
of each of the salts [R 441]? 
How many grams of potassium-hydrogen sulphate are required 
to give 1 liter of a solution of normal concentration in respect 
to (a) potassium-ion, (b) hydrogen-ion, (c) sulphate-ion? 
b. Make a solution of sodium bicarbonate and test it with 
litmus paper (?) and with Congo red paper (?). Why do some 
acid salts show little or no acid reaction towards indicators? 
Define carefully, and illustrate, the terms: normal (neutral) 
salt, acid salt, and basic salt [R 400]. 
90. Sulphates. Place some ferric sulphate in a porcelain 
crucible supported on the clay triangle, and heat strongly [Hood] 
with the blast-lamp, continuing the heating after all the water 
has been driven off (?). What are the properties of the vapor 
given off (?), and what is it? What is the residue? Relate 
this result to that in 88 f. Recall action of heat on dehydrated 
gypsum (26). Classify the sulphates in accordance with this 
distinction. 
91. Properties of Sulphurous Acid [Hood]. Use a stream 
of sulphur dioxide from a cylinder of the liquefied gas, or from 
the apparatus described in 85 d. Boil half a test-tube full of 
water for two minutes and set it aside to cool for use in c. 
a. Pass a stream of sulphur dioxide for a few minutes into 
a test-tube full of water. Test the solution with litmus paper (?). 
What compound is present in the aqueous solution of the gas? 
Note also the odor of the liquid (?). Formulate the interac- 
tion, showing all the substances present. Divide the solution 
into three portions. 
b. Boil one portion persistently in an evaporating dish [Hood], 
noting from time to time the odor and reaction towards litmus (?). 
In respect to the result, does the solution of this gas resemble that 
of hydrogen sulphide, or that of hydrogen chloride? §92] 
SULPHUR 
87 
c. Pass sulphur dioxide through the water that was boiled and 
to this add barium chloride solution (?). To ascertain whether 
this action is easily reversible, add excess of pure hydrochloric 
acid (?). 
d. To the second portion add bromine-water (?) until the 
color is permanent (?). Now add barium chloride to the mix- 
ture (?) and then pure hydrochloric acid (?). 
What chemical properties of sulphurous acid are illustrated in 
a, b, c, and d, respectively? 
e. Leave the third portion of the sulphurous acid for several 
days exposed to the air in an open test-tube or bottle. Then 
add barium chloride and pure hydrochloric acid, and compare 
the result with that in c. 
/. To 2-3 c.c. of potassium dichromate solution, add three 
or four equivalents (a large excess) of dilute sulphuric acid. 
What substances does the mixture contain? Lead a stream 
of sulphur dioxide through the solution until no further change 
is observed (?). 
g. Take 2-3 c.c. of potassium permanganate solution, treat 
as in / (?), and answer the same questions (?). 
h. Fill a bottle with the gas by upward displacement, intro- 
duce some moistened litmus paper or grass, and a small piece 
of an apple, and close with a glass plate (?). Place another 
piece of an apple in an evaporating dish. Later, remove the first 
piece of apple from the bottle and place it on a watch-glass. 
After exposure to the air for a day or more, compare the 
pieces of apple (?). 
What properties of sulphurous acid are illustrated in e, f, g, 
and h, respectively? 
92. Sulphites. 
a. To 1 g. of sodium sulphite add any dilute mineral acid 
(that is to say, one of the common acids, but not an organic 
acid such as acetic) (?). Formulate this action completely. 
b. Dissolve a minute amount of sodium sulphite in water 
and add bromine-water in excess (test? The color must remain). 
Remove the excess of bromine by boiling. Add barium chloride 
solution (?) and then pure hydrochloric acid (?). Compare this 
experiment with that in 91 d, consider whether it is probably the 
molecular sodium sulphite, or the sulphite-ion, which is oxidized, 
and make the equation accordingly. 
c. Heat persistently about 1 g. of sodium sulphite in a porce- 88 
SULPHUR 
[§ 94 
lain crucible, supported on the clay triangle over a blast-lamp. 
When cool, acidify with hydrochloric acid (?) and note the 
odor. If any sulphur is precipitated, account for its formation. 
d. Place about 1 g. of sodium bisulphite in a hard glass test- 
tube and heat cautiously with the tube in a horizontal position 
(why?). Note the odor (?) and whether any vapor condenses (?). 
This behavior is typical of that of many acid salts. What would 
be the final effect of heating sodium bisulphite more strongly and 
for a longer time? In what way is the behavior of potassium 
bisulphate somewhat different (89 a), and why? 
93. Thiosulphates. 
a. Dissolve about 5 g. of sodium sulphite in about 20 c.c. of 
water in a small flask. Add 4-5 g. of flowers of sulphur to the 
solution and boil gently over a small flame for 10-15 minutes. 
Filter off the clear yellow solution and divide into two parts. 
b. To one portion add excess of any dilute mineral acid (?). 
Note the odor. 
c. Take 10 c.c. of potassium iodide solution and dissolve in 
it a few small crystals of iodine [R 276] (?). Now pour the second 
portion of the solution from a slowly into this mixture [R 448] (?). 
How can this action be used for estimating the quantity of free 
iodine, and what substance then acts as the indicator? For 
what purpose was the potassium iodide employed? 
d. Heat persistently about 1 g. of sodium thiosulphate in a 
porcelain crucible over a blast-lamp (?). Note the appearance 
of the residue. When cold, add dilute hydrochloric acid (?) 
and identify the products. If any odor was observed during 
the heating, can you now account for it? 
94. Reduction of Sulphur Compounds [Instructions]. Mix 
a pinch of any salt of a sulphur acid with an equal amount of 
anhydrous sodium carbonate. Slightly char the end of a match 
from which the head has been removed, and rub the charred part, 
which should be about an inch in length, with a heated crystal 
of hydrated sodium carbonate. Moisten the above mixture with 
water, place some of it on the end of the match, and heat in the 
reducing region of a small Bunsen flame. Put the result on 
a clean silver coin lying in a watch-glass and moisten with one 
drop of water (?). Examine the coin (?). Then add some dilute 
mineral acid and note the odor (?). This, known as the "hepar" 
test, is a test for sulphur in any form of combination. CHAPTER XII. 
OXYGEN COMPOUNDS OF THE HALOGENS. 
95. Hypochlorous Acid from Bleaching Powder. 
a. Take about 2 c.c. of bleaching powder* with 20 c.c. of 
water in a test-tube, shake from time to time and finally filter 
to obtain a clear solution. Meanwhile arrange an apparatus 
(Fig. 11, p. 25) to generate carbon dioxide, using marble and 
hydrochloric acid. Pour most of the clear bleaching powder 
solution into another test-tube, and pass carbon dioxide through 
it for 5 minutes. What is the precipitate [R 476]? Filter again, 
to obtain a clear solution of hypochlorous acid for use in c. 
b. In the rest of the bleaching powder solution dip strips 
of litmus paper. Leave one in the solution (?). Does bleaching 
powder solution bleach? Hang the other in the air and examine 
later (?). What acid here liberates the hypochlorous acid? 
To what class of chemical actions does that on the litmus belong? 
c. In the hypochlorous acid solution from a place small 
pieces of, (a) litmus paper, (b) paper with printing on it [R 597], 
(c) paper with writing in ink [R 895] and (d) in pencil [R 569], 
and (e) colored calico. Observe and record the effect on each 
(?). Which of these owe their color or blackness to free carbon, 
and which to colored organic compounds? Does hypochlorous 
acid oxidize free carbon? What does it oxidize? 
d. How could you prepare an aqueous solution of pure calcium 
hypochlorite [R 474]? 
96. Chlorine Water [Hood], Set up an apparatus to generate 
chlorine as in 39 b and use in 96 a and in 97 a. 
a. Make 10 c.c. of an aqueous solution of chlorine in a test- 
tube. To the solution add a drop of indigo solution [R 476] (?). 
b. What evidence does experiment a furnish that hypochlorous 
acid is a more active oxidizing agent than is atmospheric oxygen? 
Why is it thus more active? 
* From a freshly opened "tin can" of the substance. When kept 
in a bottle it is likely to be decomposed by the carbon dioxide in the 
air. 
89 90 
HYPOCHLOROUS ACID, ETC. 
[§97 
97. Chlorates [Hood]. 
a. Dissolve 3 g. (weighed on laboratory scales) of solid 
potassium hydroxide in 7 c.c. of water in a test-tube and saturate 
(Test? The solution must cease to feel soapy) the solution with 
chlorine. While the saturation is proceeding, calculate the 
volume of chlorine (at 0° and 760 mm.) required to interact with 
3 g. of potassium hydroxide, one atomic weight of chlorine being 
needed for each molecule of potassium hydroxide. At five 
bubbles to 1 c.c., how many bubbles of chlorine will be used? 
Observe how many bubbles issue from your apparatus in fifteen 
seconds, and calculate how long the operation may be expected to 
take (?). Crystals will appear during the process of saturation 
and will increase in quantity as the liquid afterwards cools. 
Filter off the crystals on a small filter paper, and examine the 
filtrate and the crystals (in b), separately, as follows: 
Add to the filtrate dilute nitric acid (this is to destroy potas- 
sium hydroxide, in case any remains: no equation needed), and 
test with a few drops of silver nitrate solution (?). What radical 
is shown by this test to be present (64 a)? What product is 
thus shown to have been formed by the interaction of chlorine 
and potassium hydroxide? 
b. Examine the crystals from a with a lens and describe them. 
Dry the crystals, heat them in a narrow tube, and test for 
oxygen (?). Dissolve the residue from this operation in distilled 
water and add silver nitrate solution (?). What substances 
constituted the crystals and the residue, respectively? From 
the behavior of the former substance during making, what do you 
infer as to its solubility? Is the inference correct (Appendix IV)? 
What effect was observed on adding silver nitrate solution to 
a solution of potassium chlorate (64 a)? How may the chlorate 
radical be distinguished from that of the chlorides? The crystals 
of potassium chlorate made in a are not free from traces of 
potassium chloride (why?), and could not therefore be utilized 
for this test. What method should you suggest for purifying 
the chlorate [R 481]? 
i c. To a minute amount of finely powdered potassium chlorate 
add a few drops of pure, concentrated hydrochloric acid (?). 
The yellow substance is formed by decomposition of one of the 
products [R 483] (?). How would a chloride behave with 
hydrochloric acid? 
Give the three ways of distinguishing chlorides from chlorates. §98] 
HYPOCHLOROUS ACID, ETC. 
91 
98. Perchlorates. 
a. Measure 600 c.c. of water into your 1-liter bottle, and 
mark the level reached. Observe the temperature and pressure 
of the air and calculate the weight of potassium chlorate which 
will be necessary to give 600 c.c. of oxygen under these conditions 
(the tension of aqueous vapor may be neglected, as the vapor will 
occupy only about 10 c.c. of the 600 c.c. at 18°), and at the 
same time leave the perchlorate and chloride as a residue. 
This stage is reached when one-fifth of the total oxygen has been 
evolved: in other words, take so much of the chlorate as, if 
completely decomposed, would furnish five times 600 c.c. 
Fill the 1-liter bottle with water and invert it over the pneu- 
matic trough. Weigh the calculated amount of chlorate into 
a hard glass test-tube, which has previously been closely fitted 
with a one-hole cork and delivery tube, and see that the appa- 
ratus has been made air-tight. Gently heat the chlorate and 
collect in the 1-liter bottle enough oxygen to fill the bottle to the 
mark, measured, of course, when the mark is at the same level 
as the water in the trough. Proceed slowly towards the end 
so as to allow the gas to cool, stop heating when the mark is 
reached, and remove the delivery tube at once from the water. 
Pour the melted substance into a mortar before it has time to 
solidify. Pulverize the mixture. 
The mixture consists mainly of the chloride and perchlorate 
of potassium. The solubilities (grams of the salt dissolved by 
100 c.c. of water) of these salts are as follows: 
15° 20° 100° 
Potassium chloride 33 35 56 
Potassium perchlorate 1.5 1.8 20 
To separate the substances, calculate approximately the amount 
of potassium chloride which must be present when one-fifth of 
the oxygen has been liberated: 
Shake the powder persistently with an amount of cold water 
just sufficient to dissolve this salt. Cut, fold, and place in a 
funnel a filter paper just large enough to hold the undissolved 
material. Collect the latter upon the filter and wash it with a 
few drops of cold water. Calculate the amount of water which 
at 100° will dissolve the residue, assuming it to be potassium 
10 KC103 -» 6 KC104 + 4 KC1 + 3 O2. 92 
HYPOCHLOROUS ACID, ETC. 
[§ 99 
perchlorate. Dissolve it in this amount of water by boiling, 
and allow the solution to stand for an hour or two. Collect the 
crystals upon a filter, wash them as before, and dry them. 
b. Dissolve a little of the substance in distilled water and 
test with silver nitrate solution (?). Explain (64 d). 
To a minute amount of the crystals add a few drops of pure 
concentrated hydrochloric acid [R 483] (?). Why does the 
result differ from that when potassium chlorate was treated 
with the same acid (97 c)? 
Place about 1 g. of the crystals in a narrow test-tube, heat, 
and test for oxygen (?). 
How could you distinguish a perchlorate from a chloride, and 
from a chlorate ? 
99. Bromic and Iodic Acids. 
a. Take two test-tubes and place in one a minute fragment 
of iodine and in the other 2-3 drops of bromine-water. Add 
about 5-10 c.c. of water and a little carbon disulphide to each, 
and shake (53 a and 57 a). The carbon disulphide is added 
simply for the purpose of collecting the halogen and making its 
presence obvious. Now pass chlorine (generated as in 39 6), a 
few bubbles at a time, through (or add chlorine-water, a few 
drops at a time, to) the water in the test-tubes, alternately, 
and shake vigorously after each addition of chlorine until a 
change is seen [R 486] (?). Which of the halogens is first 
affected, and why? 
b. To about 10 c.c. of water in a test-tube add a single drop 
of potassium iodide solution and then a single drop of potassium 
bromide solution. Shake. Pour away three-fourths of the 
solution and add water. Introduce also a few drops of carbon 
disulphide. Now pass chlorine (generated as in 39 6), a few 
bubbles at a time, into the liquid, or add chlorine-water a 
little at a time, shaking vigorously after each addition of 
chlorine (?). Continue until no further changes occur, and 
explain all the changes which are observed (?). This procedure 
is used in analysis for recognizing a bromide in presence of an 
iodide. 
c. Prepare some dilute bromic acid by taking 2-3 c.c. of 
potassium bromate solution and adding an equal volume of 
dilute sulphuric acid (?). Make the equation for this double 
decomposition. Is the action complete (65 a)? In what follows, 
disregard the substances present with the bromic acid, and place 
i §99] 
HYPOCHLOROUS ACID, ETC. 
93 
the latter only in the equation. Drop into this solution a 
single small crystal of iodine and shake repeatedly, allowing 
the mixture to stand for some minutes after each shaking (?). 
Pour off the solution from any undissolved iodine, and to the 
clear liquid add a few drops of carbon disulphide (?). What 
free halogen is here detected? What does this show in regard 
to the relative tendencies of bromine and iodine to unite with 
oxygen? 
What inference can you draw from a in regard to the relative 
activity of chlorine, as compared with bromine and iodine, 
towards oxygen? What would be the action, of iodine upon a 
solution of chloric acid? 
Which variety of chemical change was here observed? How 
could you show, by a single experiment, that, although no change 
is visible, the bromic acid actually is formed when the sulphuric 
acid is added, above, and that it is the bromic acid, and not 
the potassium bromate, which interacts with the iodine? CHAPTER XIII. 
THE ATMOSPHERE, NITROGEN, AMMONIA. 
100. Preparation of Nitrogen from Air. Place a large plug of 
copper turnings in the center of a hard glass tube (Fig. 12, p. 26). 
Fit with corks and short glass tubes, and connect with the short 
tube of the aspirator (Fig. 10, p. 19). Fill completely with 
water the bottle and long tube of the aspirator and close the 
latter with a screw clamp [Storeroom]. Arrange a vessel to 
catch the water discharged. Now heat the copper red-hot and 
then partly open the clamp so as to allow the water to be sy- 
phoned off in a slow stream. The air will pass over the heated 
copper. What change does the copper undergo, and what col- 
lects in the bottle? After three-fourths of the water has run out, 
close the clamp, disconnect the hard glass tube, attach a deliv- 
ery tube in its place, elevate the end of the syphon, and replace 
the nozzle by a small funnel supported by a clamp. Pour water 
into the funnel, and drive the gas over into a bottle of water 
inverted in the pneumatic trough. Ascertain whether this gas 
supports combustion (?). Describe the gas as regards color and 
smell (?). What other gaseous substances, besides nitrogen, 
does this gas contain? 
Other ways of removing oxygen from the air are described 
elsewhere (16, 101, and 107 d). 
101. Proportion (by Volume) of Oxygen in the Air [Quant.]. 
Provide a large test-tube with a two-hole cork (a rubber 
stopper is apt to slip out in use). Into one hole fit a short 
piece of glass tubing terminating in a rounded nozzle, the tip 
of which projects but little beyond the bottom of the stopper. 
Into the other hole fit a short glass rod. Test the apparatus 
for air-tightness. Connect the upper end of the glass tube with 
a short-stemmed funnel by means of a piece of rubber tubing 
(15 cm. long) as in Fig. 26, and support the funnel in a clamp. 
Disconnect the test-tube, temporarily, and remove the glass 
rod from the stopper. Prepare an alkaline solution of potassium 
pyrogallate by mixing 3 c.c. of pyrogallic acid solution with 
20 c.c. of a solution of potassium hydroxide specially prepared 
94 § 102] 
ATMOSPHERE, NITROGEN, AMMONIA 
95 
for this experiment [Instructor], and pour this into the funnel. 
The following operations should consume as little time as possible, 
as the alkaline solution gradually 
absorbs oxygen from the air of 
the room, and thereby becomes 
useless for further absorption. 
Now open the clamp and permit 
this solution to fill the rubber 
and glass tubes completely down 
to the opening of the nozzle. 
Replace the test-tube, fitting the 
stopper tightly into its mouth. 
Finally, reinsert the glass rod, 
and so inclose a volume of air 
equal to the content of the test- 
tube and at the temperature and 
pressure of the atmosphere. 
Now open the clamp, taking 
care not to warm the test-tube 
by handling (use a piece of filter- 
paper when touching the test- 
tube). A few drops of the 
alkaline solution will enter the 
test-tube and, as the oxygen is 
absorbed, more of the solution 
will flow in. Close the clamp 
and invert the test-tube once or twice in order to bring the 
liquid thoroughly in contact with the inclosed air. Finally, 
while the test-tube is in the inverted position, reopen the clamp 
and equalize the levels of the liquid in test-tube and funnel by 
raising or lowering the former. Then close the clamp, restore 
the test-tube to its original position, and mark the positions of 
the surface of the liquid and of the bottom of the stopper by 
means of paper labels or rings cut from rubber tubing. 
Disconnect the test-tube and wash out the liquid, taking care 
not to get the alkaline solution upon the hands. Then, by 
means of a burette filled with water, measure the volumes 
required to fill the test-tube up to the lower and upper marks, 
respectively (?). The former is the volume of the oxygen, the 
latter that of the air. Calculate the percentage of oxygen in 
the air by volume (?). 
Fig. 26 96 
ATMOSPHERE, NITROGEN, AMMONIA 
[§ 104 
102. Other Components and Density of Air. 
a. Place 2-3 c.c. of clear barium hydroxide solution in the 
bottom of a small beaker and leave it exposed to the air for some 
hours (?). 
b. Blow air from the lungs through a glass tube into 2-4 c.c. 
of clear barium hydroxide solution (?). Explain (?). 
c. How may the presence of aqueous vapor in air be demon- 
strated (34 6)? How may its quantity be measured? 
d. The weight of a measured volume of air, or of nitrogen, 
may be determined by the method described in 127. From 
the data so obtained the density may be calculated. 
103. Nitrogen. 
a. Place about 10 g. of pure sodium nitrite and about 8 g. 
of ammonium chloride in a 250 c.c. flask fitted with safety and 
delivery tubes (Fig. 11, p. 25). If b is to be performed, insert 
between the flask and the delivery tube a U-tube containing 
calcium chloride for drying the gas. 
Clamp the flask by the neck to a ring-stand, add about 15 c.c. 
of water, and warm gently [Caution!]. As soon as the action 
begins, remove the flame, bring a dish of cold water under the 
flask, and cool it for a few seconds at a time so that the action 
may not become too violent, but may run uniformly. After 
sufficient time has been allowed for the displacement of air 
from the apparatus, fill a bottle with the gas over water in a 
pneumatic trough. Has the gas odor or color? Does it support 
combustion? 
b. (Two students working together.) In a piece of hard 
glass tubing, fitted with corks and short pieces of glass tubing, 
place a porcelain boat half filled with powdered magnesium. 
Connect one end of this tube to the outlet tube of the flask in 
a generating nitrogen. Heat the magnesium strongly (two 
Bunsen burners may be necessary). What action is noticed? 
What is the color of the product? Transfer the contents, when 
cold, to a dry test-tube, close with a cork, and use in 104 b. 
May the same product be formed when magnesium is heated in 
the air? What other compound would be formed under the 
latter conditions? Examine the glass tube and name the 
shining black substance on the inside surface [R 630] (?). 
104. Ammonia. 
a. Fit a small flask with a cork and L-shaped exit tube, and 
connect the latter with a U-tube. Put a little water in the § 105] 
ATMOSPHERE, NITROGEN, AMMONIA 
97 
bend of the latter so as just to close the passage. Test the 
apparatus for air-tightness. Place in the flask a mixture of 
powdered quicklime and ammonium chloride, about 10 g. of 
each, and warm gently [Hood]. After the air has been dis- 
placed, the whole of the gas should dissolve in the water. Use 
this solution of ammonium hydroxide in 105. 
If required to determine the density of ammonia, which of 
the various methods should you select (17 a, 86, or 127)? 
b. To the product from 103 b add a little water, boil, and 
note the odor (?). What other substances would behave in the 
same way as does magnesium nitride? 
c. Heat a small piece of gelatine in a dry test-tube and note 
the odor (?). 
106. Ammonium Hydroxide: An Inactive Base: Salts of 
Ammonium. 
a. Test the reaction towards litmus paper of the solution 
made in 104 a (?). What substance is present? Hold a glass rod 
dipped in concentrated hydrochloric acid over the solution (?). 
What substance is shown by this test to be present? Formulate 
the relations (in equilibrium) of all the substances in the solution. 
b. Expose 1-2 c.c. of the solution from 104 a in an evaporat- 
ing-dish for 24 hours and then note the odor (?) and test with 
litmus (?). Heat [Hood] another small portion in an evaporat- 
ing-dish for some minutes, and note the odor from time to 
time (?). Does the aqueous solution of this gas behave like 
that of hydrochloric acid, or like that of hydrogen sulphide? 
What other gases resemble ammonia in this respect? 
c. Neutralize (test?) the remainder of the solution from 104 a 
with dilute sulphuric acid and evaporate to dryness on a water 
bath (?). Formulate this action after the model 
in 71a (second par.), and explain what happens 
during neutralization to each of the substances 
present in the ammonium hydroxide solution. 
Scrape the residue into the middle of the 
dish, invert over it a funnel smaller than the 
dish, the stem of which has been closed with a 
paper plug, and heat the center of the dish 
strongly and persistently with a small flame 
(Fig. 27) (?). To learn whether the sublimate is identical with 
the residue, examine it for the ammonium radical (106 d, below), 
and the sulphate (88 b) radical. 
Fig. 27 98 
ATMOSPHERE, NITROGEN, AMMONIA 
[§ 105 
d. Dilute 1-2 c.c. of ammonium chloride solution and add to 
it 1-2 c.c. of sodium hydroxide solution (?). Note the odor (?). 
Formulate, study, and explain this action according to the 
directions in 71 a (second par.). Include in the formulation the 
liberation of the ammonia. What is an inactive base? 
e. The evolution of ammonia when an active base is added to a 
solution of any ammonium salt is used as a test for the latter. 
Why would not simply heating the salt by itself (as in 105 c 
and /) serve as a test? What salt of ammonium that we have 
used gives, when heated, no ammonia [R 514, 862] (?). Con- 
versely, what substance when heated gave ammonia, yet con- 
tained no ammonium salt (104 c)? What other substances 
behave thus [R 515, 627]? 
f. Place some ammonium chloride in the middle of an open, 
hard glass tube. Support this in a very slightly inclined (5°) 
position by means of a clamp attached close to one end. Put 
pieces of moistened litmus paper (both colors) in each end, and 
heat the salt strongly (?). Watch closely the effect on the 
papers at each end (?). What does this experiment show to be 
the action of heat on ammonium chloride? Which gas appeared 
first at the ends of the tube, and why first at both lower and 
higher ends? What should be the relative speeds, by calculation, 
of the two gases [R 126]? Why does the second gas reach the 
ends so very much later than one might expect? Has gravity 
any influence on the result? CHAPTER XIV. 
OXIDES AND OXYGEN ACIDS OF NITROGEN. 
106. Preparation of Nitric Acid [Hood]. 
a. Pulverize about 15 g. of sodium nitrate and place it in a 
dry retort or distilling-flask [Storeroom]. Cover the salt with 
concentrated sulphuric acid and wait until the liquid has per- 
meated and moistened the entire mass. Support the vessel by a 
clamp upon a sand bath and allow the neck of the retort (or side- 
tube of the flask) to extend to the bottom of a small flask (the 
receiver, Fig. 28). In order that 
the vapor of the nitric acid may 
condense, this flask is immersed 
in a vessel of cold water, and is 
covered with filter paper which 
is continually moistened. Heat 
the retort gently until a sufficient 
amount of nitric acid has been obtained, and preserve the product 
in a corked test-tube for use in b [Caution! Serious wounds may 
be caused by allowing this liquid to come in contact with the 
skin]. What is the composition of "concentrated" nitric acid 
[R 526], and how does the acid here made differ from the 
"concentrated" acid? What law teaches us to expect that the 
former will be more active (and dangerous to handle) than the 
concentrated acid? 
b. Note the color of the acid prepared in a (?). Blow some 
air from the blast through the acid (?). What is the color of 
pure nitric acid? To what substance was the color of this 
sample due, and by what action was it formed? What property 
of nitric acid does its formation indicate? Blow the moist air 
of the breath over this specimen (?). What property does this 
indicate? Determine the boiling-point of anhydrous nitric acid 
by boiling this sample in a distilling-flask with a thermometer 
immersed in the vapor (?). 
107. Nitric Oxide. 
a. Into a small flask, fitted as in Fig. 11 (p. 25) and containing 
about 10 g. of copper, pour 10 c.c. of water and then an equal 
Fig. 28 
99 100 
ACIDS OF NITROGEN 
[§ 107 
amount of concentrated nitric acid. Collect the gas over water 
in the pneumatic trough. Note the color of the gases first 
formed, and observe the color of the pure gas finally collected over 
the water. Fill two bottles (for b, c) and the large test-tube 
(for d) with the gas. 
The production of colored gases, when copper is added, is 
used as a test for nitric acid. 
b. Into one bottle introduce a burning match (?). Note also 
the effect of opening this bottle to the air (?). This effect 
may be used as a test for nitric oxide, or, conversely, for oxygen. 
How should you apply it for each of these purposes? 
c. Into the second bottle lower a deflagrating spoon with a 
very little vigorously burning, red phosphorus (?). What change 
in volume does the gas undergo in this action? 
d. Transfer without loss the nitric oxide in the 
test-tube to a small beaker filled with water and 
inverted in the pneumatic trough. Prepare some 
oxygen by placing 1 g. of sodium peroxide in a side- 
neck test-tube (Fig. 29) and introducing water, 
drop by drop, from the dropper. Fill the test- 
tube with oxygen and add this to the nitric oxide 
(?), thus securing equal volumes of the gases. 
Shake the beaker, keeping the mouth well im- 
mersed, until no further change occurs. Transfer 
the remaining gas, which must be either nitric 
oxide or oxygen, back to the test-tube. Note its 
volume, and determine what gas it is (?). What 
relative volumes are (a) used for the interaction and (b) re- 
quired by the equation? 
How might the proportion of oxygen in the air be determined 
by application of this interaction? 
e. Prepare 10 c.c. of a concentrated solution of ferrous- 
ammonium sulphate [Note 38, p. 80] (or ferrous sulphate) and 
divide into three portions. Into one pass a gentle stream of 
nitric oxide (?). Boil the liquid (?). 
f. Add to the second portion of ferrous-ammonium sulphate 
solution an equivalent amount of dilute sulphuric acid, heat 
to boiling, and add nitric acid drop by drop (mix after each drop) 
until there is no further action (?). What gas is liberated? 
g. Dissolve a single crystal of sodium nitrate in 1-2 c.c. of 
water and add a part of this solution to the remainder of the 
Fig. 29 § 109] 
ACIDS OF NITROGEN 
101 
ferrous-ammonium sulphate solution from e. Pour concen- 
trated sulphuric acid cautiously and steadily down the side of 
the test-tube until it forms a considerable layer at the bottom of 
the tube. Note the brown ring between the layers, and explain 
by reference to e and f [R 530]. This constitutes a delicate 
test for nitric acid or a nitrate. In what way does the avoidance 
of mixing (and consequent ring-formation) contribute to the 
delicateness of the test? 
h. Take 2-3 c.c. of concentrated nitric acid in a test-tube, 
warm it slightly, and lead through it a stream of nitric oxide (?). 
By waiting until the air has been wholly displaced, make certain 
whether the colored gas is formed by an interaction of the 
nitric oxide with the nitric acid, or simply by contact with the 
air in the test-tube (?). To observe the color of a gas, do not 
look across the test-tube, but down the tube at a sheet of white 
paper. 
108. Nitrogen Tetroxide. 
a. Fit a hard glass test-tube with a cork and L-shaped exit 
tube, and see that it is air-tight. Place 8-10 g. of lead nitrate 
in the tube and clamp it in a horizontal position. Tap the tube 
until the salt settles in a layer, leaving a wide channel above it. 
Prepare a strong solution of sodium hydroxide by dissolving 2 g. 
of the solid in 7 c.c. of water and allow the delivery tube to 
reach the bottom of this solution. Now heat the lead nitrate (?) 
persistently until gas is no longer given off, or until the liquid is 
no longer soapy to the touch. If all the gas is not absorbed in 
the alkali, test the escaping bubbles for oxygen (?). Label the 
solution and set it aside for use in 113 d. 
b. What is the residue? What other nitrate have we decom- 
posed in the same way (42)? This behavior when heated is 
typical of the nitrates of the heavy metals, and may be used 
for identifying them. Which nitrates, when heated, would 
leave the metal, instead of the oxide [R 130]? Why do com- 
mercial specimens of mercuric oxide [R 779], when heated in the 
preparation of oxygen, frequently give off a brown gas? 
109. Principles Involved in Making Nitric Acid. 
a. Addition of copper (107 d) to a liquid containing nitric 
acid gives red vapors. Is this a test for any substance con- 
taining the nitrate radical, or only for nitric acid? To answer 
this question, dissolve a little sodium nitrate in water, add copper, 
and warm (?). 102 
ACIDS OF NITROGEN 
[§no 
b. Was nitric acid formed in 106 on mixing sodium nitrate 
and sulphuric acid, before the distillation began? Solve this 
question by mixing sodium nitrate (finely pulverized) with 
concentrated sulphuric acid, adding a very little water [Caution] 
and agitating for a minute or so. Lower a glass rod dipped in 
ammonium hydroxide solution into the test-tube (?). Apply 
also the copper test as in a (?). 
c. Is the action of sulphuric acid upon sodium nitrate revers- 
ible? Take 2-3 c.c. of saturated sodium-hydrogen sulphate 
solution and add to it an equal or even greater volume of pure 
concentrated nitric acid. Cool the mixture in a stream of cold 
water and stir with a glass rod (?). The salt solution must be 
saturated, otherwise the experiment will fail. Examine with a 
lens the crystalline product that separates out (?). If the action 
is reversible, what enabled us to obtain a large yield of nitric acid 
in 106? 
d. Will other acids behave like sulphuric acid? Mix some 
pulverized sodium nitrate with phosphoric acid, agitate for a 
minute or two, and apply the copper test as in a (?). Could 
phosphoric acid be used in the preparation of nitric acid as in 
106? Why? Could hydrochloric acid be used [R211, 526, 537]? 
Could hydrofluoric acid be used [R 282, 526]? Give reasons 
for your answers. 
110. Properties of Nitric Acid. 
a. Test dilute nitric acid with litmus paper (?). 
b. Add 1 g. of sulphur to 2-3 c.c. of concentrated nitric acid 
and boil [Hood] for two or three minutes (?). Is there any 
evidence of action? Pour the clear liquid into another test- 
tube, dilute with water, and test for the sulphate radical (?). 
What property of nitric acid is here shown? 
c. The interaction of dilute (18 c) and of concentrated (18 d) 
sulphuric acid with metals has already been studied. Try 
the action of (a) magnesium and (b) zinc, separately, either 
upon dilute or upon concentrated nitric acid, and of (c) copper 
upon both, and explore the whole action thoroughly in each of 
the four cases as follows: 
Fit up a side-neck test-tube with a dropping-funnel passing 
through a perforated cork, and attach a delivery tube (or use 
an ordinary test-tube with cork and delivery tube). Place a 
small amount of the metal in the tube and admit the acid 
from the dropping-funnel. After the air has been displaced, § 110] 
ACIDS OF NITROGEN 
103 
collect the gas over water in a test-tube inverted in the pneu- 
matic trough (or in an evaporating-dish). 
If the gases in the generating tube remain colored, nitrogen 
tetroxide is present. If the gas is at first colored, but becomes 
colorless, nitric oxide is present: confirm by admitting air to 
the tube in which it has been collected (To see color, look down 
the tube) (?). Hydrogen, if liberated alone, would show neither 
of these properties, but might be identified by its inflammability 
(?). If both hydrogen and nitric oxide are liberated, why may 
we not feel confident of being able to cause the former to burn 
when thus diluted? How can the nitric oxide be separated 
(107 d or e) so as to leave the hydrogen in an inflammable condi- 
tion? Examine the gas in each case for these three substances. 
If ammonia is formed in any of these four cases by complete 
reduction of the nitric acid, where will it be found, and in what 
condition? (Consider all the circumstances carefully, or you 
will answer wrongly.) Test for its presence (105 d) (?). 
Evaporate on a water bath [Hood] the solution remaining in 
the test-tube after any one of these experiments (?). Collect 
the residue and heat it in a dry test-tube (?). In what form of 
combination was the metal (108 a)? 
d. Grasp a test-tube by means of a strip of folded paper (Fig. 8, 
p. 16), place in it a piece of granulated tin, and add some con- 
centrated nitric acid (?). When the action has exhausted itself, 
add much water and boil. Fit a small filter paper carefully into 
a funnel [Note 24, p. 10], collect the solid product upon the filter 
and wash [Note 39, below] precipitate and paper with water. 
Test the filtrate as it runs through to see whether it becomes 
neutral (?). Inference? Spread the filter paper with the precip- 
itate upon a water bath or radiator to dry and ascertain as in 
108 a whether the product is a nitrate (?). Why would the test 
in 107 g be unsuitable here? 
e. Comparing dilute and concentrated nitric acid with the 
same forms of sulphuric acid, what points of resemblance and of 
difference have you observed? 
Account for the differences in the actions of dilute and of con- 
centrated nitric acid in b, c, and d, in respect to the gaseous prod- 
uct of reduction which is typical of each. 
f. Dip a piece of wool in concentrated nitric acid, or note 
the nature of the products formed when the acid falls upon 
the hands or clothing (?). Would cotton behave in the same 104 
ACIDS OF NITROGEN 
[§ H3 
way? Explain [R 528]. Moisten the stained wool with am- 
monium hydroxide (?). 
g. To 1-2 c.c. of nitric acid add 3-4 c.c. of pure, concen- 
trated hydrochloric acid, warm gently, and note the appear- 
ance and odor (?). Will these acids, singly, attack all metals? 
Explain (?). What metals are attacked only by the mixture 
(aqua regia), and why? What form of combination do the 
metals assume? 
Note 39. - In filtering, observe the directions in Note 24 (p. 10). 
To wash a precipitate first let the mother liquor drain away com- 
pletely and press the precipitate with a spatula. Then cover the 
contents of the funnel, including the whole paper (why?), completely 
(and repeatedly, if necessary) with the washing material. When the 
washing is complete, dry the product by pressing with dry filter 
paper. 
111. Nitrous Oxide. 
a. In a test-tube or small flask provided with a cork and 
delivery tube (Fig. 11, p. 25), place 10 g. of ammonium nitrate. 
Heat cautiously with a small flame [Care!] and, after the air 
has been expelled, collect the gas in two bottles over water 
(warm water, if available. Why?). Why does the gas collect so 
slowly, relatively to the vigor of the action? What are the rel- 
ative volumes of the products at 100°? 
b. Into one bottle lower a glowing splinter of wood (?). 
c. Into the other bottle lower a deflagrating spoon contain- 
ing a very little burning, red phosphorus (?). If this experi- 
ment were to be conducted in a closed vessel, what, if any, 
change in pressure would be observed after the products had 
cooled? 
112. Nitrates. 
a. How does lead nitrate behave when heated? What other 
nitrates behave like it? How does ammonium nitrate behave 
when heated? 
b. Take 2-3 g. of sodium nitrate in a hard glass test-tube, 
and heat strongly and persistently until the evolution of gas 
ceases. Test the escaping gas for oxygen. Use the residue in 
113 a. What nitrates behave in this way when heated? 
113. Nitrites and Nitrous Acid. 
a. When the residue from 112 b has cooled, add not more than 
3 c.c. of water, shake vigorously until the whole has dissolved, 
and divide into three parts. To one portion add dilute sul- § 115] 
ACIDS OF NITROGEN 
105 
phuric acid (?). How could a nitrite be distinguished from a 
nitrate? 
b. To 5 c.c. of starch emulsion add a drop of potassium iodide 
solution and some dilute sulphuric acid, and then introduce a 
little of the solution from a (?). 
c. Dilute 1-2 c.c. potassium permanganate solution with a 
large excess of dilute sulphuric acid, and add a drop of this 
mixture to the solution from a (?). The actions in a, b, and c 
serve for the detection of nitrites and nitrous acid. What other 
characteristic property of nitrites has been encountered (103 a)? 
d. Examine now the solution obtained by leading nitrogen 
tetroxide into sodium hydroxide (108 a). Take a portion of the 
solution and acidify (test?) with dilute sulphuric acid (?). To 
the mixture add a drop of diluted potassium permanganate 
solution (?) or some starch emulsion containing a drop of potas- 
sium iodide (?). What substance was present? 
To ascertain whether this alkaline solution contains a nitrate 
as well as a nitrite, the latter must first be eliminated. To the 
remainder of the alkaline solution, transferred to a small flask, 
add at least 5 g. of ammonium chloride [Hood] and heat to 
boiling (?). Explain the evolution of ammonia (?). What other 
gas is given off (103 a)? When the action is entirely over, add 
about 10 c.c. of water, and shake. Prepare 2-3 c.c. of a concen- 
trated solution of ferrous-ammonium sulphate [Note 38, p. 80] 
(or of ferrous sulphate), add to it 1-2 c.c. of the solution to be 
examined, and complete the test for a nitrate described in 
107 g (?). Write now the equation for the action of nitrogen 
tetroxide on sodium hydroxide. 
114. Active (Nascent) State of Hydrogen. Dilute some po- 
tassium permanganate solution with water, and add an equal 
volume of dilute sulphuric acid to it. Divide into two parts. 
Through one pass a stream of hydrogen gas from the laboratory 
supply or from a Kipp's apparatus (?). To the second add some 
zinc dust, and shake (?). Interpret the result [R 543] (?). 
115. Identifying an Unknown Substance: I. Obtain [In- 
structor] a single, unknown solid substance. It will contain one 
of the following radicals: 
ammonium 
chloride 
bromide 
iodide 
peroxide 
sulphide 
sulphite 
bisulphite 
sulphate 
bisulphate 
thiosulphate 
chlorate 
perchlorate 
nitrate 
nitrite 
hydroxyl (base) 106 
ACIDS OF NITROGEN 
[§ 115 
The positive radicals will be limited to NH4, Na, K, and Ca, of 
which only the first is to be identified. Record at the time the 
result of each observation. Record negative results also. 
a. External Examination. Record the state (?), crystalline 
form (?), color (?), and odor (?). 
b. Solubility and Reaction of Solution. Use a few particles to 
find out if it is soluble in water (?). If in doubt, proceed as 
in 29 a. Test also with litmus papers (?). 
c. Effect of Heating. Heat 0.5 g. in a dry test-tube. Does 
it melt (?) or otherwise change (?), and does it give off gas or 
vapor? Note the odor (?). 
If water vapor is given off and condenses (?), the substance 
may be a hydrate, acid salt, or calcium hydroxide. Incline the 
mouth of the tube downwards, drive all the water off, dry out 
the tube with filter paper, and continue heating. Does it now 
change (?) or give off gas or vapor? 
If a solid sublimate appears (?), what is it? Note the odor 
(?) and apply the test for the positive radical (?). 
A colorless gas with an odor (?) may be ammonia or sul- 
phur dioxide (?). 
A colorless, odorless gas may be oxygen (test?). Which 
three of the above radicals will give oxygen? What substance 
will remain, in each case, when all the oxygen has been driven 
off? Keep the tube and residue for use in e. 
A colored gas may be nitrogen tetroxide (?). Inference? 
d. Action of Concentrated Sulphuric Acid. To 0.5 g. of the 
substance add two or three drops (not more) of concentrated 
sulphuric acid (?). If a pale yellow gas appears [Caution!] do 
not heat, as the gas (?) is explosive. If no gas appears, warm 
gently (?). 
A colorless gas (bubbling) which fumes in the breath (?). 
Two possible sources (?). 
A colorless gas, non-fuming, with an odor may be hydro- 
gen sulphide or sulphur dioxide. One possible source of former 
(?) and three of latter (?). 
A colorless gas, non-fuming, odorless may be oxygen (?). 
A colored gas may be vapor of iodine or of bromine (?). 
It may be nitrogen trioxide (?). If yellow, it is chlorine di- 
oxide (?). Inference as to radical (?). 
No gas (no bubbling) indicates a sulphate or a base (?). 
e. To the residue from c, par. 5, add two or three drops of § 1151 
ACIDS OF NITROGEN 
107 
concentrated sulphuric acid (?). What is the inference if the 
gas is brown (?) and if it is colorless, but fumes in the breath? 
f. Conclusion. In some cases the foregoing experiments fail 
to distinguish between two possible radicals. Apply special 
tests in these cases. In each case, if a special test exists, con- 
firm your conclusion by applying it. 
g. Report. State your conclusion, with reasons therefor (?). 
h. Obtain a second unknown, and proceed as before (?). CHAPTER XV. 
PHOSPHORUS. 
116. Phosphorus. What difference in general chemical 
behavior do the two allotropic modifications of phosphorus 
exhibit [R 550]? What product is formed when phosphorus 
burns in excess of oxygen, and what is formed when the oxygen 
is limited in amount [R 556]? 
117. Phosphine [Hood]. Place a very small piece of cal- 
cium phosphide in a little water in a beaker (?). What mode 
of forming ammonia is similar to this, and how is it similar? 
Repeat, using dilute hydrochloric acid instead of water (?). 
What mode of forming hydrogen sulphide is similar to this, 
and how is it similar? In what ways does phosphine differ 
from ammonia [R 553]? Which of the differences are shown 
in these experiments? Why should we expect ammonia and 
phosphine to be alike? Test with litmus the water in which 
the calcium phosphide was placed (?), and explain. 
118. Metaphosphoric Acid. 
a. Throw 2 g. of phosphorus pentoxide, in minute portions 
at a time, into a beaker containing 10 c.c. of cold distilled 
water (?). Allow the liquid to stand for a few minutes, or 
until clear. Test the liquid with litmus paper (?). What 
acid is present [R 556]? Use the solution for b and c and 119 a. 
Why could not the product made by burning phosphorus in a 
closed volume of air be used in this case? 
b. To a part of the solution from a add silver nitrate solu- 
tion, a little at a time, shaking between additions, until a per- 
manent precipitate (color?) is formed (?). Is an action like 
this reversible? Is this action incomplete? To answer, add 
one or two drops of diluted (1 : 4 Aq.) ammonium hydroxide 
solution, observe whether the precipitate increases, and ex- 
plain. This is a reaction of what ion? What other substances 
would give it? 
c. To 1 c.c. of albumin solution, add one or two drops of 
the solution from a [R 560] (?). This is a reaction of the free 
acid only, and not of metaphosphate-ion. 
108 § 120] 
PHOSPHORUS 
109 
119. Orthophosphoric Acid. 
a. Dilute the remainder of the solution of metaphosphoric 
acid from 118 a with 10 c.c. of water, and boil in a small flask 
vigorously for an hour or more. If necessary add more water 
to make up for the loss by evaporation. Cool the solution, 
treat portions of it with silver nitrate and with albumin, as in 
118 b and c, and answer the same questions. How may the 
formation of this acid, during the boiling, be hastened [R 557]? 
Like all double decompositions, the one with silver nitrate is 
reversible, and is therefore incomplete. Name the interacting 
substances in the reverse action (?). To stop this reverse 
action, destroy the acid by adding ammonium hydroxide solu- 
tion one drop at a time, noting the effect, shaking, and examin- 
ing again. What evidence is there that the action now goes 
further forward? 
Finally, add concentrated nitric acid (?). Which way does 
the action now go? 
b. Heat 1 g. of red phosphorus with 5 c.c. of dilute nitric 
acid in a test-tube (?). When the action has ceased, filter, if 
necessary, and drive off the water and excess of nitric acid 
completely by evaporation [Hood] on a water bath. Mix 
with a few drops of concentrated nitric acid the syrup which 
remains, and evaporate once more. It is essential that all the 
nitric acid be finally removed (why?). Redissolve the syrup 
in water and test with litmus paper (?). 
Treat part of the solution with silver nitrate as in 118 6, 
and answer the same questions (a black precipitate with silver 
nitrate is due to phosphorous acid [R 561] formed by incom- 
plete oxidation). 
c. Place in a test-tube 5 c.c. of the solution of ammonium 
molybdate in nitric acid, add to it two drops (only) of the solu- 
tion of orthophosphoric acid prepared in b, and warm gently (?). 
This is a very delicate test for phosphoric acid, or orthophos- 
phate-ion. 
120. Phosphates. 
a. Take some sodium phosphate (secondary sodium ortho- 
phosphate) solution and test it with litmus paper (?). What 
ions are present? Are acid salts always acid towards litmus? 
If not, explain why they are not. Explain also the actual 
reaction of this solution. 
b. To a very small part of the sodium phosphate solution add 110 
PHOSPHORUS 
[§121 
silver nitrate solution until the precipitation is complete (?). 
What is the precipitate (see 119 a and 6)? What are the reac- 
tions towards litmus of the sodium phosphate (a), and silver 
nitrate solutions singly? Test the mixture with litmus paper 
(?). What ion is evidently formed, and what product is there- 
fore present? 
c. Prepare a little "magnesia mixture" by adding to 1 c.c. 
of magnesium sulphate solution a few drops of ammonium 
hydroxide and then excess of ammonium chloride solution. 
Add to the rest of the sodium phosphate solution a little of 
this mixture (?). In making the equation, disregard the am- 
monium chloride, which is added only to prevent precipitation 
of magnesium hydroxide. This is another test for the presence 
of what ions? 
d. Strongly heat [Blast-lamp] 2 g. of dry sodium phosphate 
in an open crucible for twenty minutes, or until no further 
change is observed (?). Dissolve the cold mass in water (it 
dissolves very slowly), and test a portion of the solution with 
silver nitrate solution (?). This is a reaction of what ion? 
Take the remainder of the solution, liberate the acid (?) by 
adding acetic acid, and introduce a few drops of the liquid 
into a solution of albumin (?). 
Make a table showing the effects of the three phosphoric 
acids upon albumin and the colors of their silver salts. How 
could you identify salts of the three acids? 
e. Heat strongly [Blast-lamp] 2 g. of microcosmic salt as 
in d. Note the odor (?) and reaction towards moistened litmus 
paper (?) of the vapors given off. Dissolve the residue in cold 
water and use the tests tabulated in d to learn what salt has 
been formed. 
f. Make a bead on a straight platinum wire as in 3 c, using 
microcosmic salt instead of borax. Of what must the bead 
consist? Now fuse with it (3 d) a minute particle of cupric 
oxide (?). What difference do your experiments show as to 
the relative stabilities of NaPO3, NaNO3 (112 6), and KCIO3 
(17 a)? 
121. Halides of Phosphorus. 
'a. What were the actions of water on the tribromide (54 6) 
and tri-iodide (58 b) of phosphorus? 
b. Place 2-3 c.c. of phosphorus trichloride in a dry test- 
tube and blow the breath over the tube (?). Add water drop § 121] 
PHOSPHORUS 
111 
by drop (?) until about 5 c.c. has been used, then boil the solu- 
tion (Fig. 8, p. 16). Test the vapor with litmus paper (?) 
and with a rod dipped in ammonium hydroxide (?). Evapo- 
rate [Hood] the solution to a syrup on the water bath (?). 
c. Transfer part of the syrup from b to a small test-tube and 
heat until the gas evolved may be ignited at the mouth of the 
tube (?). Note the odor of this gas before igniting it (?). Con- 
tinue heating until the action is over. Ascertain according to 
120 d which of the phosphoric acids constitutes the residue (?). 
d. Dilute 1 c.c. of potassium iodide solution with water and 
dissolve in the liquid a crystal of iodine. Add to this solution 
a little of the syrup from b, and shake (?). 
e. Place upon a watch-glass 5 or 6 small granules of phos- 
phorus pentachloride and blow the breath over them (?). Throw 
them into 2-3 c.c. of water in a test-tube (?) and boil. Test 
the solution with litmus (?). To a small part of the cold 
solution add excess (test?) of silver nitrate solution (?). Fil- 
ter. What remains upon the paper (?). To the filtrate add 
diluted (1 :4 Aq.) ammonium hydroxide drop by drop (shake 
between drops) (?). CHAPTER XVI. 
CARBON. 
122. Carbon Dioxide by Oxidation. 
a. Fit a hard glass test-tube with a cork and L-tube. Mix 
intimately in the mortar 1 g. of pulverized cupric oxide with 
1 g. of pulverized wood charcoal and place in the tube. Clamp 
the test-tube in a horizontal position, and let the L-tube reach 
to the bottom of a test-tube containing limewater. Heat the 
powder persistently [Blast-lamp] and let the gases pass through 
the limewater (?). Examine the residue by rubbing vigorously 
under .water in the mortar and washing away the lighter par- 
ticles (?). What property of carbon is here illustrated? What 
important industrial processes depend upon this sort of reaction? 
b. Mix 2 g. of litharge and 2 g. of charcoal, and test as in a 
using, however, only a Bunsen burner for heating (?). Answer 
the same questions (?). 
123. Carbon Dioxide, Preparation. 
a. Place a few small pieces of magnesite (magnesium car- 
bonate) in a hard glass test-tube fitted with a cork and L-tube 
and heat strongly. Pass the gas through 5 c.c. of limewater 
in a test-tube (?). What is the residue [R 573]? 
b. Fit up a generating-flask (Fig. 11, p. 25) and connect with 
two wash-bottles (Fig. 24, p. 82) containing water and con- 
centrated sulphuric acid, respectively (what is the use of each 
of these? The latter is unnecessary if 126 is omitted). Place 
in the flask some pieces of marble and pour upon them diluted 
hydrochloric acid. Collect the gas in three bottles by upward 
displacement of air, and cover them with glass plates. 
What substances could be substituted for marble in this 
experiment? What other sources of carbon dioxide have been 
encountered (15 c, 122 a, 123 a; see also 126 a and c, 128 b, 
129 b, 133 5)? 
124. Carbon Dioxide, Properties. 
a. To one bottle add a little water, close with the hand, and 
shake (?). Is the gas soluble in water, or not? 
112 §126] 
CARBON 
113 
Use the second to compare the density of the gas with that of 
air. Employ baryta-water as a test. 
b. Set an empty bottle (filled with air) over the remaining 
full one, and mouth to mouth with it, and withdraw the plate. 
After ten minutes, replace the glass plate between the bottles, 
remove the upper bottle, along with the plate, and set it upright 
upon the table. Slip the plate aside for a moment, add some 
limewater, replace the plate, and shake (?). Did the greater 
density of the carbon dioxide prevent its diffusing into, and 
displacing a part of the air? What are the relative rates of 
diffusion of air and carbon dioxide? 
c. Take two test-tubes containing distilled water, pass a 
current of the gas into one, to saturation, and test each with 
litmus paper (?). Boil the solution, and test again with litmus 
(?). Explain. 
d. Lead the gas into a little sodium hydroxide solution in a 
test-tube until the solution is saturated (test? Note 37, p. 79). 
Let the solution stand until it dries spontaneously (first residue). 
Heat the dry residue (?) in a test-tube, and determine what two 
things are given off (?). 
To this residue after heating (second residue) add dilute 
hydrochloric acid until all action (?) ceases. Evaporate the 
solution on the water bath, and examine and taste this final 
residue (?). Having recognized the products of the last action, 
and taking into account the preceding observations, state what 
the nature of the second and first residues must have been. 
Write equations for all actions. 
125. Molecular Weight of Carbon Dioxide [Quant.]. 
a. Determine the weight of a measured volume of the gas by 
the method used for sulphur dioxide (86), and calculate the 
weight of the gram-molecular volume. What further informa- 
tion must we have to enable us to determine the formula? 
b. Use the quantitative results obtained in the synthesis of 
carbon dioxide (41) along with this molecular weight, to calcu- 
late the weights of carbon and of oxygen in a molecular weight 
of the gas. What further steps are necessary in order to fix the 
atomic weight of carbon? 
126. Carbon Monoxide [Hood]. 
a. Heat about 10 g. of oxalic acid crystals with concen- 
trated sulphuric acid in a generating-flask (Fig. 11, p. 25), and 
fill a bottle over water with the gas which is given off. Shake 114 
CARBON 
[§127 
with limewater (?). With what substance should we wash 
the gas to remove the carbon dioxide? Arrange a wash-bottle 
to purify the gas. Fill two bottles with the purified gas over 
water. Test one with limewater again (?). If the gas is pure, 
burn that in the other bottle, add limewater at once, close 
quickly, and shake (?). 
b. Devise a way of ascertaining roughly the relative volumes 
of the two gases generated in a, and measure the proportion in 
a test-tube full of the mixed gases. 
c. Pass a stream of the purified carbon monoxide over a 
little pulverized cupric oxide, heated in a boat in a hard glass 
tube (?). What gas is formed? What remains in the boat? 
What is here the reducing agent? 
127. Molecular Weight of Carbon Monoxide [Quant.]. 
Obtain [Storeroom] a round-bottomed, 250 c.c. flask. Fit it 
with a rubber stopper through which passes a short, straight 
tube. Attach to the latter a short piece of rubber tubing 
closed with a strong pinch clamp. Make a mark on the neck 
at the bottom of the stopper, so as to be able to measure the 
exact content of the flask up to the stopper. Place 30 c.c. of 
water in the flask, insert the stopper, remove the clamp, and 
boil the water with a small flame for about five minutes, so as 
to drive out all the air. Close the rubber tube with the clamp 
and remove the flame quickly, wipe the flask and allow it to 
cool. When it has assumed the temperature of the air, weigh 
the whole carefully, suspending the flask on the balance by a 
thread tied round the neck (?). Connect with the apparatus 
delivering pure carbon monoxide, and open the clamp a very 
little so as to admit a slow stream of the gas. When the flask 
is full, close the clamp, disconnect from the generating appara- 
tus, open the clamp for an instant to restore the pressure to 
that of the atmosphere, and weigh again (?). The gain in weight 
represents the weight of the carbon monoxide. Read the 
barometer and thermometer (?). Subtract from the barometric 
reading the aqueous tension at the observed temperature. 
Ascertain the volume of the flask by filling with water to the 
mark from the graduated cylinder (?). 
Calculate the weight of the G.M.V. of the gas (?). 
To what class of gases would this method of determining the 
density and molecular weight be applicable? Why could not 
this method be used for carbon dioxide? § 129] 
CARBON 
115 
128. Methane (Marsh Gas). 
a. Pulverize about 5 g. of fused sodium acetate and about 
20 g. of soda-lime (a mixture of quicklime and sodium hy- 
droxide). Mix the ingredients intimately in the mortar, and 
place in a large test-tube fitted with a one-hole cork and deliv- 
ery tube (Fig. 9, p. 17). Rap the test-tube gently so as to form 
a space for the passage of the gas. Then clamp the tube close 
to the cork in a slightly inclined (5°) position, so that it slopes 
toward the mouth (why?). Slip over the tube a cylinder of 
wire gauze, and, beginning at the rear or sealed end, heat the 
contents gently until the evolution of gas is uniform. When 
all the air is displaced, collect one bottle of gas over water. 
Attach a small nozzle to the end of the delivery tube and 
ignite the gas. Note the color and degree of luminosity of the 
flame (?). Hold over the jet a dry inverted beaker and observe 
one product of the combustion (?). 
b. Hold the bottle containing the gas mouth downward 
and apply a light (?). Quickly pour into the bottle some lime- 
water, and shake (?). What volume of oxygen is required for 
the complete combustion of one volume of methane, and what 
ratio will the resulting volume of gases bear to the original 
volume of methane, at 0° and at 100°, respectively? 
129. Ethylene [Hood]. 
a. Fit a 250 c.c. flask with a doubly-bored cork, through 
which pass a dropping-funnel and L-tube. Attach a gas- 
washing bottle containing a little water, and connect an L- 
shaped delivery tube. Test the apparatus to see that it is 
air-tight. Place in the flask about 20 g. of phosphorus pent- 
oxide, and clamp it to a ring-stand over a sand bath. Introduce 
into the bulb of the dropping-funnel (or substitute, 44 6) some 
alcohol. Finally, heat the phosphoric anhydride, and admit the 
alcohol drop by drop. 
b. Fill a bottle with the gas over water and apply a light (?). 
Quickly pour some limewater into the bottle, and shake (?). 
Attach a nozzle to the exit tube of the washing-bottle and raise 
the other tube clear of the water (why?), ignite the gas, and 
observe the luminosity of the flame. What commercial use 
has ethylene [R 594]? Hold a cold, dry beaker over the flame 
(?). What are the products of complete combustion of all 
hydrocarbons? 
c. Detach the nozzle, reattach the delivery tube to the exit 116 
CARBON 
[§131 
tube, and lower the other tube of the washing-bottle once more. 
Place 1 c.c. of bromine [Caution!] in a test-tube, cover it with 
5 c.c. of water, put the test-tube into a beaker filled with cold 
water, and allow the gas to bubble into the bromine. When 
the color of the bromine has disappeared, examine the contents 
of the test-tube (?). Is the product colored? Is it soluble in 
water? What do you infer as to its specific gravity? Detach 
the dropping-funnel, wash it out, and place in it the contents 
of the test-tube. Draw off the lower, oily layer into a dry 
test-tube and note its odor (?). Try its solubility in alcohol (?). 
d. Why is the accepted formula for ethylene preferred to the 
simplest? What volume of oxygen would be required to burn 
one volume of the gas completely? What would be the relative 
volumes of the products at 0° and 100°, respectively? What 
volumes of bromine vapor and ethylene would be required for 
complete combination, and what would be the relative volume 
of the product (in the state of vapor)? 
130. Acetylene. 
a. Fill a test-tube with water and invert it in water in an 
evaporating-dish. Introduce a small piece of calcium carbide 
under the mouth of the tube (?) Test the water with litmus (?). 
Bring a light to the mouth of the tube (?). Note the luminosity of 
the flame, and compare with flames of methane and ethylene (?). 
b. Can you state a general method for making hydrides of non- 
metals (such as C2H2, PH3, NH3)? Can SH2 [R 767] and C1H 
[R 846] be formed similarly? 
131. Starch and Glucose. 
a. Shake about 0.5 c.c. of starch with 20 c.c. of water and 
then boil (?). Add a few drops of the liquid to 5 c.c. of Feh- 
ling's solution* and warm the latter (?). Does starch change 
Fehling's solution? 
Place three-fourths of the remaining starch suspension in a 
flask, set it on the wire gauze, add 5 or 6 drops of concentrated 
hydrochloric acid, and boil gently for ten minutes. 
b. While this is going on, cool the rest of the starch suspen- 
sion in running water and pour it into a beaker full of cold water. 
Add one drop from 5 c.c. of a solution of potassium iodide in 
which a single crystal of iodine has been dissolved (?). 
* No. 1: 69.3 g. of CuSO4,5H2O with water to make 1 liter. No. 
2: 350 g. Rochelle salt and 100 g. sodium hydroxide with water to make 
1 liter. Mix equal volumes (measured) just before use. § 133] 
CARBON 
117 
c. Cool the contents of the flask (from a) and add sodium 
carbonate solution drop by drop, shaking between drops, and 
touching the edge of a piece of litmus paper with a glass rod 
dipped in the liquid, until the liquid gives a faint alkaline 
reaction. 
Now add a few drops of this liquid to 5 c.c. (measured) of 
Fehling's solution and warm the latter [R 605, 744] (?). Add 
more of the liquid, boil again, and continue until the blue color 
is gone. It takes 0.005 g. of glucose to reduce and decolorize 
1 c.c. of Fehling's solution. What amount of glucose was con- 
tained in the part of the liquid you added? 
132. Sucrose. 
a. Dissolve about 0.5 g. of sucrose (ordinary sugar) in 20 c.c. 
of water and repeat a and c with this liquid. Does sucrose 
reduce Fehling's solution? Do acids hydrolyze it to give 
glucose? 
b. Dissolve about 0.5 c.c. of molasses in water and test for 
glucose as in 131 a, par. 1 (?). 
133. Ethyl Alcohol. 
a. Dissolve 20 g. of glucose syrup in 150 c.c. of water. Break 
up a piece of yeast and add it to the syrup. Fill a flask (or 
bottle) to the base of the neck with the mixture, plug the mouth 
of the flask with cotton, and set the whole aside in a warm place 
for 3-4 days. 
Fit to the flask a 1-hole stopper, L-tube, and rubber tube 
terminating in a straight glass tube. Take 15 c.c. of limewater 
in a test-tube, insert the glass tube to the bottom of this, and 
shake the fermented liquid in the flask (?). Note the gas 
evolved and its reaction with limewater (?). In what form of 
solution was the gas before the shaking [R 193]? 
Filter the liquid and place it in a larger flask, fitted with a 
cork and L-tube, and connect (Fig. 20, p. 57) with a condenser 
[Storeroom]. Distil off about 50 c.c. Place the distillate in a 
distilling-flask [Storeroom] fitted with a thermometer, connect 
with the condenser, boil with a small flame, and catch the part 
which passes over betweeen 75° and 93°. 
b. Note the odor of the distillate (?). Test it with litmus 
papers (?). Saturate a tuft of asbestos wool with the liquid, 
set the tuft on the base of the stand, and apply a light (?) 
Hold a cold, w.-m. bottle over the flame, to recognize one 
product (?). Close the bottle and test the gas in the bottle by 118 
CARBON 
[§ 135 
shaking with limewater (?). Make the equation for the com- 
bustion (?). If you burned alcohol vapor and pure oxygen, 
what relative volumes should you use, and what relative vol- 
umes of the products (measured as gases) would be formed? 
c. To a few drops of the alcohol add 1 c.c of sodium hydroxide 
solution. Pulverize one or two (not more) crystals of iodine, 
add a part of the powder to the mixture, shake vigorously, and 
warm (?). The amount added must not be sufficient to give 
a permanent brown tint to the Equid. The precipitate is iodo- 
form CHI3 (related to chloroform CHCI3). 
134. Acetic Acid. 
a. To 1 g. of sodium acetate add some dilute sulphuric acid, 
and warm. Note the odor (?). How could you use this action 
to make acetic acid? How is it manufactured [R 609]? 
b. Take 5 c.c. of acetic acid. Test with litmus paper (?). 
Recall its interaction with zinc or iron (18 e) (?). To the acid 
add 3-4 g. of litharge and boil gently for a few minutes (?). Fil- 
ter, if necessary, while hot, and set the clear 
solution aside to crystallize (?). What is the 
common name of the product [R]? 
c. If, in 132 a, acetic acid had been used in- 
stead of hydrochloric acid, what modification in 
the directions would have been necessary? 
135. Distillation of Wood. 
a. Take three-fourths of a hard glass test-tube 
full of sawdust and wood chips. Arrange the 
apparatus as in Fig. 30. The test-tube is in- 
clined slightly downwards towards the mouth. 
The wide test-tube, in which the distillate is to 
be caught, is surrounded by cold water, and a 
nozzle is inserted in one of the holes in the stop- 
per. Heat the contents of the test-tube, at first gently, and 
later strongly, until no more vapors are evolved. 
During the heating, set fire to the issuing gas (?). Is the 
flame luminous, or not? Compounds of what element must be 
present? 
Examine the condensed liquid. What liquid or liquids are 
seen? Test the liquid with litmus papers (?). What dissolved 
substance causes this reaction [R Wood, 610: Coal, 613]? 
Examine, describe, and name the residue in the hard glass test- 
tube (?). Name five observed products from distilling wood (?). 
Fig. 30 § 136] 
CARBON 
119 
b. Place a small piece of charcoal in a test-tube half full of 
water (?). Now hold it under the water with the reverse end 
of the file, and boil the water for several minutes (?). When 
the whole has cooled, test once more the tendency of the char- 
coal to float (?). Explain (?). 
c. Boil dilute solutions of litmus and indigo, separately, with 
pulverized animal charcoal, and filter each liquid (?). The 
activity of the charcoal is much increased by previous heating 
in a covered crucible. 
136. Coal. 
a. Repeat 135 a, using bituminous coal. Test for hydrogen 
sulphide in the coal gas by holding a piece of filter paper, 
moistened with lead acetate solution, in the unlighted gas (?). 
Name six observed products from distilling coal (?). • 
b. Coal Analysis [Quant.]. Weigh a dry porcelain crucible 
and lid or cover (?). Place in it 1 g. of coal and weigh again (?). 
Set the crucible, uncovered, in the air-bath at 105° for exactly 
one hour. Cover the crucible and, when cold, weigh it again (?). 
The loss in weight is the "moisture" [R 611]. Calculate the 
per cent of moisture (?). 
Now place the crucible, covered, on the clay triangle, about 
four inches above the mouth of a Bunsen burner. Heat it for 
eight minutes, in such a way that the flame heats the sides as 
well as the bottom of the crucible. Allow the crucible to cool 
(while covered) and weigh again (?). The loss in weight is 
"volatile matter." Calculate the percentage of this in the 
original coal (?). 
Finally, replace the crucible, without cover, in a slanting 
position on the clay triangle, and heat once more. Heat care- 
fully, at first, to avoid loss by decrepitation and ejection of 
particles. The complete burning of the "fixed carbon" may 
take several hours. When only a light-colored ash remains, 
cover the crucible, allow it to cool, and weigh again (?). Cal- 
culate the percentage of fixed carbon (?) and of ash (?). 
Calculate the calorific power in B.T.U.* as follows: 
B.T.U. = (% fixed carbon X 14,670 + AF)/100, 
* The calorific power is reckoned by engineers in British Thermal 
Units, 1 B.T.U. being the heat required to raise one pound of water 1° F. 
Dividing the number of B.T.U. by 1.8 gives the number of calories per 
1 g- 120 
CARBON 
[§ 139 
where V is the per cent of volatile matter and A varies with V 
as follows: 
V = 2-15% A = 23,400 V = 30-35% A = 17,100 
V = 15-30% A = 18,000 V = 35-40% A = 16,200 
137. Formation and Hydrolysis of an Ester. 
a. To 2 g. of sodium acetate in a test-tube add 2 c.c. of ethyl 
alcohol and 1 c.c. of concentrated sulphuric acid. Agitate for 
a minute or two, warm very slightly (do not boil!), and note the 
odor [R 617] (?). This is a test for acetic acid or an acetate. 
b. Repeat, using amyl alcohol instead of ethyl alcohol (?). 
c. Place 10 c.c. of water in one test-tube and 0.5 c.c. of methyl 
acetate CH3(CO2CH3), an ester, in another. Test each with 
blue litmus paper (?), then mix and test again [R 618] (?). If 
the result is not definite, test the mixture again later (?). 
138. Soap and its Properties. 
a. Place in a porcelain dish a piece of fat the size of a pea, 
and add 4 c.c. of alcohol and five drops of a 50 per cent solu- 
tion of sodium hydroxide (made with 1 g. of the solid and 1 c.c. 
of water). Stir constantly and boil very gently until the odor 
of alcohol is no longer perceptible, then stop. The alcohol is 
used as a common solvent for the fat and the alkali. What is 
the residue [R 619]? 
b. Dissolve the soap in hot water, cool, and to one-fourth of 
the solution add dilute hydrochloric acid, and shake vigorously 
(?). Withdraw the floating coagulum by means of a glass rod, 
suspend it in water in a test-tube, add a few drops of sodium 
hydroxide, and heat until solution takes place. What do you 
conclude from its solubility in the alkali? 
c. To another quarter of the soap solution add calcium chloride 
solution (?). Explain the action of hard water [R 620] on soap 
solution. 
d. To the remainder of the cold soap solution, add sodium 
chloride solution (?). This is called "salting out" [R 619], and 
is a case of coagulating a colloid [R 623]. To what class of solu- 
tions does this show soap solution to belong? 
139. Colloidal Suspensions. 
a. Shake some arsenic trioxide with 25 c.c. of cold water 
vigorously for several minutes, filter, and to the filtrate add an 
equal volume of hydrogen sulphide solution. Arsenious sul- 
phide As2S3 is formed, but remains in colloidal suspension. § 140] 
CARBON 
121 
b. Pour the suspension from a into a square bottle, and 
examine it in sunlight, or, better still, by holding it close to an 
incandescent bulb. Look first through it towards the light (?). 
Does it appear to be transparent and clear, or no? Now look 
at it from a position at right angles to the direction of the light, 
and answer the same question (?). With a microscope, the 
particles in such solutions can be perceived, individually [R 622]. 
c. Divide the suspension from a between 5 clean test-tubes. 
Keep one, corked, for reference. To one add sodium chloride 
solution (?), to another dilute hydrochloric acid (?), to the third 
calcium chloride solution (?), dissolve a little sugar in the fourth 
(?), and observe them from time to time. Note which coagu- 
lates last (?). 
The positive ion is here the coagulating agent. How does 
valence affect coagulating power? Do non-ionized, non-col- 
loidal substances like sugar produce coagulation? 
After a day or two, does the arsenious sulphide in the refer- 
ence test-tube coagulate or settle of its own accord? 
d. Dissolve a single particle of rosin in 1 c.c. of alcohol. 
Add the solution to a test-tube full of water (?). Examine in 
the light as in b (?). Cork and keep to see whether settling 
takes place (?). 
e. Summarize the special properties of colloidal suspensions (?). 
f. Boil 300 c.c. of distilled (or soft) water in a large beaker, 
and add to it, a few drops at a time, 3 c.c. of ferric chloride 
solution. The salt is thus somewhat hydrolyzed and contains 
suspended ferric hydroxide Fe(OH)s. Color? 
Examine this suspension in the light as in b (?). 
Take 5 test-tubes full of the liquid, keep one for reference, 
and add to each of the others a very dilute solution (0.1 N) of 
one of the following coagulants: sodium chloride, sodium sul- 
phate, sodium carbonate, calcium chloride. This colloid is 
coagulated by the negative ion. Note the amount and time 
required in each case (?). What is the effect of valence? 
140. How Soap Cleanses. 
a. Place 1 c.c. of kerosene in one test-tube and 1 c.c. of cotton- 
seed oil in another. Add about 10 c.c. of water to each, shake 
vigorously, and place in the rack (?). Is a permanent emulsion 
formed? 
Now add to each 2 c.c. of soap solution (ivory soap : Aq :: 1 : 
10), shake again, and observe as before (?). 122 
CARBON 
l§ 140 
b. Boil 200 c.c. of water in a flask. Saturate the test-tube 
brush with ferric oxide (pulverized) suspended in cottonseed 
oil (6 g. : 100 c.c.) [Instructor] and push it into a test-tube. 
Add about 15 c.c. of the hot water, and work the brush in the 
tube (?). Does hot water alone remove the ferric oxide and oil? 
Remove the brush, pour out the water, place 15 c.c. of hot 
soap solution in the test-tube, and work the brush in the tube 
as before (?). Remove the brush, pour the contents of the test- 
tube into a 100 c.c. beaker, and rinse first the brush and then 
the test-tube with hot water, catching the rinsing-water in the 
beaker. Have the oil and rust been removed from the brush? 
After a short time, examine the contents of the beaker (?). 
Where is the oil (?) and in what condition? Where is the rust 
(?) and is it free from oil? 
Explain how soap solution removes grease or oil from a large 
object or a powder (?). CHAPTER XVII. 
SILICON AND BORON. 
141. Silica. Mix 1 g. of finely powdered silica with 4-5 g. 
of anhydrous sodium carbonate. Coil the platinum wire to 
watch-spring form and, by alternately heating in the Bunsen 
flame or blast-lamp, and dipping in the mixture, obtain a large 
bead and heat it strongly till all action (?) seems to have ceased. 
Place the bead in a test-tube and make others by the same 
process. Dissolve the beads in a small amount of water. Add 
hydrochloric acid a drop at a time until the solution is strongly 
acid (?). Evaporate the solution to dryness on the sand bath 
(?). Treat the residue with warm water, wash the whole con- 
tents of the dish into a test-tube, and examine (?). 
142. Analysis of a Silicate. Mix dry potassium carbonate 
with anhydrous sodium carbonate in equal proportions in a 
mortar. Coil the platinum wire to watch-spring form. Mix a 
little powdered talc (is this soluble in water? What is its com- 
mon name?) with 6-7 times as much of the "fusion mixture," 
and hold some of the result on the platinum wire in the flame of 
the blast-lamp till it is completely melted and all action (?) 
has ceased. Repeat till several beads are obtained. Treat the 
beads with boiling water in a test-tube until they are com- 
pletely disintegrated. Filter through a small filter paper and 
wash the precipitate with water. Preserve this filter paper 
and precipitate for use later. Acidify the filtrate with concen- 
trated hydrochloric acid and proceed as in 141. 
Make a hole in the paper and wash the precipitate obtained 
above into a test-tube. Add dilute hydrochloric acid, and 
warm (?). Filter, if necessary, and add ammonium hydroxide 
to alkaline reaction (?). The precipitate is aluminium hydrox- 
ide. Boil and filter. To the filtrate add a few drops of ammo- 
nium hydroxide, some ammonium chloride solution, and some 
sodium phosphate solution, and shake (?). Compare 120 c. 
143. Silicon Tetrafluoride. Mix intimately 1 g. of pulver- 
ized calcium fluoride with an equal weight of sand, place in a 
123 124 
SILICON AND BORON 
[§ 145 
test-tube, and moisten the mixture with concentrated sulphuric 
acid. Apply a gentle heat (?). Hold a glass rod, with a drop 
of water at its lower end, in the gas and examine the rod (?). 
144. Boric Acid. 
a. Pulverize some borax and make a strong solution in 
boiling water. Add concentrated hydrochloric acid until the 
solution is strongly acid, and set aside to cool (?). Filter off 
the crystals, wash with a few drops of cold water [Note 39, 
p. 104], and dry. Dissolve the crystals in the smallest possible 
amount of boiling water, and set the solution aside (?). Filter, 
and wash the crystals as before. 
b. Dissolve a part of the crystals in hot distilled water. 
Test this solution, and a sample of the distilled water, simulta- 
neously with litmus paper (?). Dip a strip of turmeric paper 
in the same solution, wrap it round the upper part of the test- 
tube, and boil the solution until the paper is dry (?). Touch 
the paper with a glass rod dipped in sodium hydroxide solu- 
tion (?). This is a test for boric acid. 
Treat the rest of the crystals with cold sodium hydroxide 
solution (?). 
c. Place on separate parts of a watch-glass a drop of concen- 
trated sulphuric acid, a drop of glycerine, and a very little 
pulverized borax. Rub the end of a platinum wire in each of 
these. Bring the end of the wire slowly up to the outer edge 
near the bottom of a small Bunsen flame. How is the flame 
colored? This is a test for a borate. 
An alternative method: Dissolve a small crystal of borax 
in 1-2 c.c. of water in a test-tube. Add a drop or two of con- 
centrated sulphuric acid and then 2-3 c.c. of alcohol. Heat 
the mixture and set fire to the vapor of the alcohol (?). 
145. Borates. 
a. Dissolve 1 g. of borax in distilled water. Test both this 
solution, and the distilled water, with litmus paper (?). 
Put two drops of the solution into a test-tube and dilute 
with water till the tube is two-thirds full. To the remainder 
add silver nitrate solution (?). Warm the very dilute solution 
and add silver nitrate solution to it also (?). For comparison, 
add silver nitrate solution to an exactly equally diluted sodium 
hydroxide solution (?). What conclusion do you draw in regard 
to the action of water on borax? Write the equation, and 
explain. § 146] 
SILICON AND BORON 
125 
b. Heat a straight platinum wire in the Bunsen flame, and, 
while yet glowing, dip it into a small quantity of borax. Re- 
turn the wire to the flame and observe the changes in the sub- 
stance (?) until it forms a bead. Try borax beads, as directed 
in 3 d, e, and f, with cupric oxide (?), manganese dioxide (?), 
and ferric oxide (?), separately. 
146. Identifying an Unknown Substance: II. Obtain [In- 
structor] a single unknown solid substance. It will either 
contain one of the following radicals, or be one of the substances 
mentioned: 
orthophosphate 
metaphosphate 
pyrophosphate 
carbonate 
bicarbonate 
acetate 
borate 
starch 
sucrose 
glucose 
ethyl alcohol 
sulphur 
The positive radicals will be limited to NH*, Na, K, and Ca, of 
which only the first is to be identified. Record at the time the 
result of each observation. Record negative results also. 
a. External Examination. Record the state (?), crystalline 
form (?), color (?), and odor (?). 
b. Solubility and Reaction of Solution. Try the solubility of 
a few particles in water (?) and test the solution with litmus 
papers (?). 
c. Effect of Heating. Heat 0.5 g. in a dry test-tube. Does 
it melt (?), char (?), or otherwise change (?), and does it give off 
gas or vapor? Odor? 
If water vapor is given off (?), the substance may be a 
hydrate, acid salt, carbohydrate, or calcium hydroxide. In- 
cline the mouth of the tube downwards, drive all the water off, 
dry out the tube with filter-paper, and continue heating. Does 
it now char (?), change (?), or give off gas or vapor? 
A sublimate indicates a salt of NH4. Test 105 d. 
A colorless gas with no odor may be carbon dioxide (test?). 
A colorless gas with an odor may be ammonia, sulphur 
dioxide, or gases from the charring of carbohydrates (?). 
d. Action of Concentrated Sulphuric Acid. To 0.5 g. add 2-3 
drops (not more) of concentrated sulphuric acid (?). If neces- 
sary, warm gently (?). 
If the substance turns black, it is a carbohydrate (?). Ascer- 
tain which one by the proper test (131, 132). 126 
SILICON AND BORON 
I§ 146 
A colorless, odorless gas may be carbon dioxide (test?). 
A gas with an odor may be acetic acid (test?). 
If there is no gas (no bubbling), the substance may be a 
phosphate or a borate (test?). 
e. Report. State your conclusion, with the reasons there- 
for (?). 
f. Obtain a second unknown and proceed as before (?). 
g. Obtain a third unknown, involving exercise 115 as well 
as 146 (?). CHAPTER XVIII. 
METALLIC ELEMENTS OF THE ALKALIES. 
147. Potassium Hydroxide. 
a. Dissolve about 30 g. of potassium carbonate [Notes 10, 
11, 12, p. 2] in 200-300 c.c. of water in a large beaker, and 
heat on a wire gauze to boiling. Slake 15-20 g. of quicklime 
in a beaker (?), using heat if necessary to start the action, and 
make the product into a very thin paste with water. Add this 
gradually, and with constant stirring, to the boiling solution (?). 
Continue boiling for a few minutes (why?). Let the mixture 
settle, and, when it is cold, decant the clear liquid (or filter 
rapidly). Use the solution in b, c, and d. 
Is calcium hydroxide appreciably soluble (Appendix IV)? 
Is calcium carbonate more or less soluble than is the hydrox- 
ide? Formulate the action and explain why it went to comple- 
tion. What kind of hydroxides alone can be made by this 
method? Which hydroxides are of this kind (Appendix IV)? 
b. Find the strength of the solution made in a by titration 
(alkalimetry). To do this, place a carefully measured volume 
(about 10 c.c.) of the clear solution in a small flask. Dilute 
with about four times its volume of water, as the concentrated 
solution is apt to decompose the indicator. Fill a burette with 
"normal" [R 182] hydrochloric acid.* Add some phenol- 
phthalein solution to the alkali and run in the acid cautiously 
until the red color just disappears. Note the volume of acid 
used. Calculate the concentration of potassium hydroxide 
in terms of a normal solution as unity (?). 
c. (Two students working together.) If the alkaline solu- 
tion is above normal, calculate the volume of the solution 
* Or normal oxalic acid may be prepared (two students working 
together), and used here. Calculate the weight of pure [Instructor] 
oxalic acid [R 616] required to make 500 c.c. of normal oxalic acid 
solution [R 182]. Weigh out [quant.] this amount on glazed paper and 
transfer it to a 500 c.c. graduated flask [Storeroom]. Dissolve the acid 
in distilled water and then fill up the flask to the mark. 
127 128 
ELEMENTS OF THE ALKALIES 
[§ 148 
required to make 100 c.c. of normal alkali. Place the necessary 
amount of the solution in a 100 c.c. graduated flask [Storeroom] 
and fill to the mark with water. (If the solution is less than 
normal, calculate and use the amount required for 200 c.c. of 
semi-normal alkali.) 
Measure (burette) 5 c.c. of acetic acid into a flask and dilute 
with about 20 c.c. of water (or take 25 c.c. of commercial vine- 
gar), add phenolphthalein, titrate with the normal (or semi- 
normal) alkali, and calculate the normality of the acetic acid (or 
vinegar) used (?). Calculate also the percentage of acetic acid 
present. 
d. Place very small quantities of the following solutions in 
separate test-tubes, dilute with water, and add excess of the 
solution of potassium hydroxide from a to each; ferric chlo- 
ride (?); cupric sulphate (?); mercuric chloride (?). Describe the 
color and structure of the precipitates [Note 40, below]. Boil 
the contents of each test-tube (?). Do the precipitates dissolve 
or change in any way? 
What kind of hydroxides can be made by this method? Do 
any metals fail entirely to form hydroxides [R 654]? 
e. Pulverize a small piece of potassium hydroxide and leave 
it exposed to the air on a watch-glass for 24 hours, or more (?). 
To a part of the product add dilute hydrochloric acid (?). 
Simultaneously, treat a small piece of sodium hydroxide in 
exactly the same way (?). Compare the results and explain. 
Note 40. -■ The structure of a precipitate may be described 
as gelatinous, flocculent, curdy, pulverulent, granular, or crystalline. 
What circumstances will determine the structure of a precipitate? 
Hereafter, describe every precipitate by terms like these. 
148. Potassium Nitrate. 
a. Dissolve 25 g. of sodium nitrate and 22 g. of potassium 
chloride in 50 c.c. of water and evaporate to half the volume 
on the sand bath. Fit a filter paper into a small funnel [Note 
24, p. 10]. As rapidly as possible decant the hot, clear liquid 
from the crystals and set it aside. Throw the crystals which 
appeared during boiling at once on to the filter, and rapidly press 
out the rest of the mother-liquor with a spatula. Examine the 
form of the crystals and ascertain what they are (?). (If they 
are too small, recrystallize a part slowly from water in a beaker 
in order to learn their form.) When the decanted liquid is cold, §149] 
ELEMENTS OF THE ALKALIES 
129 
press the product on a filter likewise. Examine this set of crys- 
tals as before (?). Compare both with the original substances. 
To understand the process, write in the blank places of the 
table (below) the solubilities (grams dissolved by 100 g. water) 
of the substances concerned (Appendix V): 
i 
10° 100° 
Potassium nitrate 246 
Sodium chloride 
10° 100° 
Potassium chloride 
Sodium nitrate 
Which of these substances will first be deposited from the 
boiling liquid? Ascertain by calculation how much of it 
(roughly) will be deposited at 100°, how much more will come 
out when the liquid cools, and how much will remain in the 
mother-liquor. What other substance will be present in large 
quantity in the hot mother-liquor, and how much of it must 
there be? How much of this product will be deposited when 
the liquid cools, and how much will be lost by remaining dis- 
solved? What per cent of the possible yield of potassium 
nitrate may we expect to get? Dry your product, weigh it, 
and calculate what per cent was secured. 
Explain why purer potassium nitrate can be obtained by 
crystallizing the product once more from water. 
b. Mix intimately in the mortar 5 g. of finely pulverized 
potassium nitrate with 2 g. of charcoal, and drop the mixture in 
small portions into a red-hot crucible (?). What gases are 
evolved? What is the residue (test with an acid)? 
c. Pulverize 5 g. of potassium nitrate and mix on paper 
[Caution] intimately with 2 g. of flowers of sulphur. Throw 
the mixture [Hood] in small portions into a red-hot crucible (?). 
What gases are evolved? Dissolve the residue and add barium 
chloride solution (?). Explain the explosive power of gun- 
powder (?). 
149. Potassium Cyanide [Poison]. How is this salt made 
[R 672]? Place 2 c.c. of potassium cyanide solution in an 
evaporating-dish, heat it, and add yellow ammonium sulphide 
solution until the color (?) no longer disappears. Evaporate to 
complete dryness [Hood]. Dissolve a part of the residue with 
water, and add ferric chloride solution (?). A black precipi- 
tate (?) indicates that the heating was not sufficient. If this 
appears, heat the residue once more and try the action of ferric 
chloride again. In the first part of this experiment, what 130 
ELEMENTS OF THE ALKALIES 
[§ 151 
property of the cyanides [R 626], and which kind of ionic chem- 
ical change, are illustrated? Is this change instantaneous, as 
is the union or disunion of ions? 
150. Reactions of Potassium Salts. 
a. Heat a little solid potassium nitrate on a clean platinum wire. 
Notice the color of the flame and examine with the spectroscope. 
Make a diagram showing the position of the lines with refer- 
ence to the D line (in the yellow), which, on account of the 
sodium present, is shown by all flames in the laboratory. 
b. Saturate 10 c.c. of warm water (40°) with potassium 
nitrate. Add this solution to an equal volume of tartaric acid 
solution in a beaker (?). Agitate and cool in a stream of water 
(?). Note, also, the effect of rubbing the inside of the vessel 
with a glass rod. Describe the product [Note 40, p. 128]. 
Filter, and wash the precipitate with a little alcohol. 
c. Dissolve a few particles of the precipitate from b in a 
drop or two of warm water and test with litmus (?). Remem- 
bering that tartaric acid H2(CO2)2C2H2(OH)2 is a dibasic acid, 
what sort of salt must the product be? 
To a few particles of the precipitate add dilute hydrochloric 
acid (?). 
To a part of the precipitate add drop by drop potassium 
hydroxide solution (shake between drops) (?). To the result- 
ing solution add concentrated hydrochloric acid a drop at a 
time. No effect can be expected until after the mixture becomes 
acid (test?). Stir vigorously with a glass rod, and cool in run- 
ning water between drops (?). Finally, try the effect of excess of 
the acid (?). 
d. Heat the rest of the precipitate strongly in an open por- 
celain crucible (?). Extract with hot water, filter, and add any 
acid to the filtrate (?). The ignition of all potassium or sodium 
salts of organic acids gives the same result. 
e. Take 2-3 c.c. potassium chloride solution and, in another 
test-tube, dilute a few drops of it with 10 c.c. of water. Then 
add some picric acid solution to each portion [Note 40, p. 128] (?). 
Explain the difference in behavior (?). 
What substance is shown to be present in a solution when we 
get the tests in b and e? 
151. Ammonium Salts. 
a. What is a common effect of heating ammonium salts 
(105 6)? Heat 1 g. of ammonium phosphate in a hard glass I 152] 
ELEMENTS OF THE ALKALIES 
131 
test-tube (?). Dissolve the residue in water and test with 
litmus paper (?). Is simple heating a test for an ammonium 
salt? Do all salts of ammonium give ammonia when heated 
(103 a; 111 a)? Observe the odors of all the salts of ammonium 
(solids and solutions) in your kit, or upon the side-shelf (?), and 
explain. 
b. Do ammonium salts impart color to the flame? 
c. Take a solution of any ammonium salt and divide it into 
three portions. To one add excess of tartaric acid solution, and 
shake (?). To the second add picric acid solution (?). Com- 
pare these results with 150 b and e. To the third add sodium 
hydroxide solution and note the odor (?). How should you 
distinguish ammonium-ion from any other ionic substance? 
Why is heating the salt not a sufficient test (104 c)? 
d. Test ammonium chloride solution with litmus (?). Do 
you infer that ammonium hydroxide is a very inactive base 
[R 647]? 
152. Sodium Carbonate by Solvay Process. 
a. Take 75 c.c. of ammonium hydroxide, dilute with 25 c.c. 
of water, and dissolve in it 25 g. of powdered ammonium car- 
bonate by shaking (ammonium hydroxide solution is used 
instead of water in order to secure ultimately a higher concen- 
tration of ammonium-ion, and therefore of HCO3- ion, than 
could be obtained with the carbonate alone, the solubility of 
this salt being too small). Then saturate the solution com- 
pletely with sodium chloride by prolonged agitation with finely 
powdered salt in a corked bottle. If crude salt is employed, it 
should be washed with water before use. Decant the clear 
liquid into another bottle, fitted with cork and two tubes, 
one of which reaches to the bottom. If, because of delay, a 
dense precipitate has appeared, proceed without decanting. 
Through the latter (long) tube, pass in carbon dioxide from the 
laboratory supply, or from a Kipp's apparatus or generator, until 
the solution is saturated. This operation may occupy an hour 
or more. During the absorption of the carbon dioxide, the exit 
tube should be closed to prevent waste of the gas. Finally, 
close the tubes with caps of rubber tubing plugged with glass rods 
and set aside over night (?). Filter off the deposit, and dry by 
pressing between filter papers. 
b. Dissolve in water a little of the solid, which must have 
ceased to smell of ammonia (why?), and test the reaction of the 132 
ELEMENTS OF THE ALKALIES 
[§ 154 
solution with litmus (?). If the solution is not acid, explain 
why it is not so. 
To part of the solid add any dilute mineral acid (?). 
c. Heat the rest in a test-tube clamped so that the mouth is 
inclined slightly downward, and ascertain what gases and vapors 
are evolved (?). When gas ceases to be given off, dissolve the 
cold residue in a very little water, test the reaction of the solution 
with litmus paper (?), and set it aside to crystallize in an open 
dish (?). Explain the reaction with litmus (?). Dry the 
crystals, and ascertain the effects upon them of (a) addition of 
an acid (?), and (b) of exposure on a watch-glass (?). 
Compare the solubilities of the carbonate (Appendix IV) 
and bicarbonate of sodium [R 656], and explain why the bicar- 
bonate is made first and then the carbonate from it. 
153. Purification of Sodium Chloride. Prepare about 150 
c.c. of a cold saturated solution of common salt by grinding the 
salt for some time in a mortar with the water. If crude salt is 
used, it must first be washed with water. Place the solution 
in a beaker, and pass hydrogen chloride into the solution. Pre- 
pare this gas by placing a handful of common salt in a gen- 
erating-flask (Fig. 15, p. 36), covering it with concentrated 
hydrochloric acid, and allowing concentrated sulphuric acid to 
fall into it from a dropping-funnel. The hydrochloric acid 
prevents frothing and steadies the stream of gas (why?). Deliver 
the gas into the solution through a thistle-tube with the mouth 
downward (?). When considerable precipitation has occurred, 
filter by putting a clean silver coin with milled edges in a fun- 
nel, pouring the liquid and crystals upon it, and pressing with a 
spatula. 
Why is the thistle-tube preferable to ordinary tubing? 
154. Reactions of Sodium Salts. Take some salt of sodium 
and try the flame test, and examine the flame with the spec- 
troscope as in 150 a. Take a solution of some salt of sodium, 
and add to one portion picric acid solution (?), and to the other 
tartaric acid solution (?). Compare all the results with those 
obtained in 150 and 151 b and c. 
How could you distinguish sodium, potassium, and ammonium 
salts from one another? How could you demonstrate positively 
the presence both of a potassium and of an ammonium salt in a 
mixture of the two without the aid of the flame test or spectro- 
scope? § 155] 
ELEMENTS OF THE ALKALIES 
133 
Which salts of potassium, ammonium, and sodium are least 
soluble? 
155. Ionic Equilibrium and the Ion-Product Constant. 
a. Dilute a few drops of methyl orange solution [R 392] with 
much distilled water. Add a few drops of an acid (?) and then 
excess of a base (?). What colors does this indicator show in 
neutral, acid, and alkaline solution, respectively? What ionic 
substance is present in the acid, and absent from the other 
solutions? 
Take some distilled water in a beaker and add to it 2-3 drops 
of methyl orange solution, and divide the liquid between three 
test-tubes. To the first two add a little acetic acid (?), to the 
third a drop of hydrochloric acid (?). To the first add some 
solid sodium chloride, and shake (?). To the second add some 
solid sodium acetate, and shake (?). What ionic substance has 
disappeared? Explain the difference in behavior [R 695]. To 
the third add solid sodium chloride, and shake (?). Explain the 
absence of effect. 
In what way did 70 b illustrate the same principle? 
b. Take three portions of a saturated solution of potassium 
chlorate in as many test-tubes. (If there is any deposit in the 
bottles, this and the following solutions must be shaken before 
use to insure saturation.) To the first add saturated sodium 
chloride solution (?), to the second saturated potassium chlo- 
ride solution (?), to the third saturated sodium chlorate solu- 
tion (?). Allow them to stand for a minute or two before 
drawing any conclusion. Explain [R 697]. The experiments 
will fail if all the solutions are not saturated. 
c. Explain why, in 153, the salt is precipitated. If the crude 
salt had contained other salts, which of them would have been 
affected by the introduction of hydrogen chloride, and which 
not? Specifically, would sodium sulphate or magnesium 
chloride have been affected, and how? If either of these would 
be affected and had been present, under what circumstances 
might it have entered into the precipitate (Appendix IV)? 
Within what limits, then, does the process give a means of 
purification? 
d. To 1-2 c.c. of concentrated hydrochloric acid add con- 
centrated sulphuric acid drop by drop (?). Explain. CHAPTER XIX. 
METALLIC ELEMENTS OF THE ALKALINE EARTHS. 
156. Calcium Oxide. Ignite [Blast-lamp] 2-3 g. of broken 
marble for 15 minutes in an open crucible placed upon the 
clay triangle (?). Stir occasionally with the platinum wire. 
When cool, add a little water (?). Test the reaction of the 
liquid towards litmus (?). Has water any effect upon marble? 
Now, add some dilute hydrochloric acid (?). Compare this 
with the action of the acid upon marble (123 6). 
How may the decomposition of the marble be arrested (?) 
and reversed (?) without altering the temperature ? What con- 
ditions permitted complete decomposition to take place here? 
157. Calcium Hydroxide. Slake a piece of calcium oxide 
and shake the product with half a liter of distilled water; let the 
solution settle, or filter rapidly, and use the clear liquid. 
a. Blow air from the lungs by means of a tube through a 
part of the limewater (?). How could you determine the 
proportion of carbon dioxide in a sample of air? 
b. Dilute the remainder of the limewater with an equal 
volume of distilled water, and pass a stream of carbon dioxide 
from the laboratory supply, or from a Kipp's apparatus or gen- 
erator, persistently through the solution (?). Write two equa- 
tions, one for each change (?). Boil a part of the resulting 
clear liquid (?). Explain. Describe all precipitates [Note 40, 
p. 128], both here and in all succeeding experiments. Why 
does the second precipitate appear to differ in quantity from 
the first? What is "temporary hardness" in water? 
158. Reactions of Calcium Salts. Diluted calcium chloride 
solution [Note 41, below] may be used for b, c, d, and/. 
a. Try the flame test and examine with the spectroscope 
(see that the platinum wire is clean. Note 42, below). Make 
a sketch of the spectrum showing the positions of the lines 
with reference to the sodium and potassium lines. 
b. To a part of the solution containing calcium-ion add 
ammonium oxalate solution in excess (?). Filter off the pre- 
134 § 158] 
ALKALINE EARTHS 
135 
cipitate and divide it into two parts. Place each part in a test- 
tube, and treat one with dilute hydrochloric acid (?) and the 
other with diluted acetic acid (?). Explain this difference in 
behavior towards hydrogen-ion [R 713]. Why was ammo- 
nium oxalate used in preference to oxalic acid? 
What are the approximate numerical values of the ion-product 
constants of calcium oxalate, calcium carbonate, and calcium 
sulphate (Appendix IV)? 
c. To the second portion of the solution containing calcium- 
ion add some dilute hydrochloric acid, mix, and then add am- 
monium oxalate solution (?). Explain [R 716] (?). If any 
precipitate appears, add more hydrochloric acid. Now add a 
large amount of sodium acetate solution (?). What is the 
precipitate (calcium acetate is soluble), and why is it formed 
[R 716]? 
d. To the third portion of the solution containing calcium- 
ion add ammonium carbonate solution (?). Warm, if necessary. 
Filter, divide the precipitate and treat parts of it with hydro- 
chloric acid (?) and diluted acetic acid (?) respectively. Ex- 
plain the result. Explain also the difference in behavior of the 
oxalate and the carbonate of calcium towards acetic acid, 
taking account of both of the solubilities of these salts, and of the 
fundamental difference in behavior between oxalic and carbonic 
acids. 
e. To the fourth portion of the solution add excess of dilute 
sulphuric acid (?). Filter and divide the clear (if not, filter 
again) filtrate into three parts (reserve one for /). To one 
small part add an equal volume of alcohol (formation of all 
precipitates, if long delayed, may be hastened by vigorous 
stirring) (?). 
Neutralize (test?) the second portion with ammonium hy- 
droxide (why?), add ammonium oxalate solution (?), and ex- 
plain. Is the sulphate or the oxalate of calcium more soluble? 
Confirm your inference by giving the solubilities (Appendix IV). 
f. What is "permanent hardness" in water [R 722]? Boil 
the third portion of the fitrate from d (?). Compare the 
result with that in 157 b. Add now a little sodium carbonate 
solution (?). Is the carbonate or the sulphate of calcium more 
soluble? What are their actual solubilities? How may per- 
manent hardness be removed? What is one objection to the 
presence of hardness in a domestic water supply (138 c)? 136 
ALKALINE EARTHS 
[§ 161 
g. To the fifth portion of the solution containing calcium-ion 
add potassium dichromate solution (?). Divide the mixture 
into two parts, and add acetic acid to one (?) and hydrochloric 
acid to the other (?). 
Note 41. - In this and all following paragraphs headed "reac- 
tions," where " diluted" solutions are spoken of, the solutions must be 
diluted with 3-4 volumes of distilled water to secure good results. 
Note 42. - After use, the platinum wire must be cleaned. Form 
upon it a borax bead, and cause the molten bead to traverse the 
wire from end to end several times. Throw off the bead. Heat 
the wire persistently in the Bunsen flame, dipping it from time to 
time in hydrochloric acid (why?), until the wire no longer colors 
the flame. If much corroded, the wire may be boiled in nitric 
acid before being heated. 
159. Reactions of Strontium Salts. Use diluted [Note 41] 
strontium chloride solution for b, c, and d. 
a. Same as 158 a. 
b. Add ammonium carbonate solution and heat (?). 
c. Add dilute sulphuric acid (?). 
d. Add a clear solution of calcium sulphate (made by shak- 
ing a little of the pulverized salt with distilled water and filter- 
ing until clear) (?). The precipitate may come slowly. Explain. 
e. Same as 158 g (?). 
160. Reactions of Barium Salts. Use diluted [Note 41] 
barium chloride solution for b, c, and d. 
a, b, c. Same as 159 a, b, c. 
d. Add a clear solution of strontium sulphate (made by 
shaking the salt with distilled water and filtering) (?). Explain. 
Compare with 159 d, and arrange the sulphates of these three 
metals in the order of solubility. 
e. Same as 158 g (?). 
Give two methods of distinguishing the compounds of the 
elements in this family. How could you tell a solution contain- 
ing the ions of a member of this family from one containing those 
of the members of the previous family? 
161. Identification of Unknown Substances. Take three 
dry test-tubes, apply to the instructor for three "unknown" 
substances, and ascertain what each is. Record negative as 
well as positive results (?). 
a. Study: (1) Physical appearance (?). 
(2) Odor (?). §161] 
ALKALINE EARTHS 
137 
(3) Solubility in water and reaction of the solution toward 
litmus (?). After the final conclusion has been reached, re- 
examine the results recorded under (1), (2), and (3), and con- 
sider if the substance found has the properties there noted. All 
results require checking in some such way. 
b. (4) Identify first the negative radical, using the methods 
described in 115 and 146 (?). 
Before beginning (4), make a fist of all the negative radicals 
known to you, and place opposite to each the gases, if any, 
which salts containing that radical, when heated, might be 
expected to give off. Consider also the means of recognizing 
these gases, if formed. 
Before heating with a drop or two of concentrated sulphuric 
acid make a list of the reactions of sulphuric acid with salts con- 
taining each of the negative radicals. Consider also the means 
of recognizing such of the possible products as are volatile. 
c. (5) Dissolve the substance in distilled water (if insoluble, 
try dilute hydrochloric acid). Identify now the positive radical, 
using the reactions for the metallic ions just studied (?). 
d. (6) Write out the experiments and reasoning carefully in 
your note-book, and make sure that they prove the substance 
to be the one you finally decide that it is, and exclude the pos- 
sibility of its being any other. See (3) above (?). Report the 
result to the instructor. CHAPTER XX. 
COPPER AND SILVER. 
162. Cuprous Chloride. 
a. Dissolve about 2 g. of cupric chloride in 15 c.c. of water 
in a small flask. Add 2-3 c.c. of pure, concentrated hydro- 
chloric acid and about 5 g. of copper, and boil [Hood] until 
the green tint is no longer perceptible in the dirty yellowish- 
brown color of the product. If a few drops added to a test- 
tube full of water confer a blue tinge upon the water, the action 
is still incomplete. What ion confers the blue tinge? What 
change do the cupric ions undergo? Is the change an oxidation 
or a reduction of cupric chloride? 
b. To a small part of the solution, when cold, add excess of 
sodium hydroxide solution (?). Why is so much of this required? 
Preserve the mixture in a corked test-tube for use in 164. 
c. Pour the rest of the solution from a into a large amount of 
water in the beaker (?). Expose some of the product, while 
covered with water, to the sunlight (?). 
d. To the rest of the product from c add concentrated hydro- 
chloric acid, and shake (?). What is the complex negative ion 
here formed [R 740]? Does it give a greater or a less concen- 
tration of cuprous-ion than does the insoluble cuprous chloride? 
Upon this basis explain the process of solution here observed. 
Pour a little of the solution into much water (?). 
e. To the rest of the solution made in d add a little chlorine- 
water (?). What ionic substance is shown by its color to be 
present? Pour this solution into much water (?). 
Define this form of oxidation, and the form of reduction in a, 
in terms of the hypothesis of ions. 
163. Cupric Hydroxide. 
a. To 1-2 c.c. of diluted cupric sulphate solution add excess 
of sodium hydroxide solution (?). Take one-third of this mix- 
ture and boil it (?). 
b. Boil 1 g. of sugar dissolved in water (or diluted glucose 
syrup) with a few drops of dilute sulphuric acid for several 
138 § 166] 
COPPER AND SILVER 
139 
minutes (?). This gives glucose and levulose [R 606]. Add 
this glucose solution to another portion of the mixture from a, 
warm gently (?), and note all changes. Make no equation. 
c. To the remainder of the mixture from a add ammonium 
hydroxide, and shake (?). What complex ion possesses this blue 
color [R 743]? Does this ion give a greater or a less concen- 
tration of cupric-ion than does the insoluble hydroxide? Upon 
this basis explain the process of solution here observed. 
164. Cuprous Oxide. Divide the mixture from 162 b, con- 
taining a precipitate of hydrated cuprous oxide, into three parts. 
a. Shake one persistently with air in a bottle, admitting 
fresh air from time to time (?). 
b. Boil the second portion (?). 
c. To the third portion add ammonium hydroxide (?). What 
is the color of the mixture? What complex ion is formed 
[R 743]? Why is cuprous oxide dissolved by ammonium 
hydroxide solution? 
Shake this solution with air. What ion is formed? Is the 
action more or less rapid than in a, and why? 
165. Cuprous Iodide. Dilute a few drops of cupric sulphate 
solution and add potassium iodide solution (?). Filter. Wash 
the precipitate [Note 39, p. 104] (?). What is the color of the 
precipitate (?), and what is it? Add part of the filtrate to some 
starch emulsion (?). Shake the rest with some chloroform (?). 
Read the footnote to p. 12. 
166. Reactions of Cupric Salts. Use diluted cupric sulphate 
solution. What is the color of cupric sulphate itself? ' To 
what is the color of the solution due? 
a. Test the reaction of the solution with litmus paper (?) 
and explain [R 647]. Is copper an active metallic element? 
b. Lead hydrogen sulphide through another portion (?). Is 
this action reversible, theoretically? Add dilute sulphuric 
acid (?). Do dilute acids act upon any sulphides (82 g)? Why 
not upon this one [R 421]? 
c. To another portion add potassium ferrocyanide solution 
[R 746] (?). 
d. Note here the interaction (75 a) of zinc with cupric-ion (?). 
e. Make a borax bead and heat with it a minute particle of 
cupric oxide in the oxidizing (?) and in the reducing (?) flame, 
as in 3 e. The latter requires patience. If cupric sulphate had 
been used here, what reaction would have taken place [R 441]? 140 
COPPER AND SILVER 
[§ 169 
f. Prepare a match (or splinter of wood) as in 94. Place on 
the end a moistened mixture of any copper salt with anhydrous 
sodium carbonate and heat in the reducing region of a small 
Bunsen flame. Break up the charred stick gently in water in 
a mortar, wash away the lighter particles, and rub residue hard 
with the pestle (?). 
167. Ammonio-cupric Compounds. To a diluted solution 
of cupric sulphate add ammonium hydroxide (?), first a drop or 
two (?), then in excess (?). Of what ion does the copper now 
form a part? Do other compounds of copper yield the same 
ion (163 c)? Which action of all those in 166 and 167 should 
you hold to give the most delicate test for cupric-ion? 
Try with the blue solution the tests in 166 b, c, and d (?). 
Are the concentrations of cupric-ion given by cupric sulphide (?), 
cupric ferrocyanide (?), cupric sulphate (?), and cupric hydrox- 
ide (?), larger or smaller than the concentration of free cupric-ion 
given by ammonio-cupric-ion? Which of these compounds 
would be dissolved by ammonium hydroxide solution, and 
which not? 
168. Cuprocyanides. To a diluted solution of cupric sul- 
phate add potassium cyanide solution [Care! Poison], first 
a drop (?), then in excess (?). Does the solution show the color 
of cupric-ion? In what form of combination is the copper 
[R 744]? Divide the solution into three parts and try the tests 
for cupric-ion given in 166 b and d (?). Would cuprous sulphide 
dissolve in potassium cyanide solution? Explain your answer. 
Does cuprous sulphide (?) give larger or smaller concentrations 
of free copper ions than does the cuprocyanide? Would potas- 
sium cuprocyanide give the bead test (166 e) or the match test 
(166 /)? 
169. Double Salts (Potassium-Cupric Sulphate). 
a. Saturate water at 70° with 5 g. of finely powdered potassium 
sulphate (about 25 c.c. will be required). Calculate the weight 
of crystallized cupric sulphate which must be taken to get 
an equimolecular proportion, and dissolve it in its own weight 
of hot water. Mix the two solutions, taking care not to allow 
any undissolved fragments of either salt to get into the mixture, 
and set the result aside to crystallize (?). Examine the form 
of the crystals and compare with those of blue vitriol (?). Dis- 
solve a part of the crystals in water and use portions of the solu- 
tion for b. §171] 
COPPER AND SILVER 
141 
b. With the solution try tests in 166 b, c and d (?). Is cupric- 
ion present? To another portion add ammonium hydroxide (?). 
How do double salts differ (a) from complex compounds like 
potassium cuprocyanide and ammonio-cupric sulphate and (b) 
from simple salts like cupric sulphate? 
170. Equivalent of Copper [Quant.]. Take a small rod of 
pure zinc, smooth the ends with a file, and weigh carefully. 
Place in a beaker an exactly known weight of crystallized 
cupric sulphate (about 2 g.), and dissolve in distilled water. 
Put the zinc in this solution, and allow them to remain in con- 
tact until the latter is completely decolorized. Remove the 
zinc, free it carefully from the brown deposit (?), and dry and 
weigh it. What weight of zinc has gone into solution? 
To avoid weighing the precipitate of copper, which it would 
be difficult to do exactly, calculate from the formula what 
quantity of copper was contained in the amount of blue vitriol 
taken (?). Calculate from your data the weight of copper dis- 
placed by the equivalent weight of zinc found in 42 b or 44 a, or, 
if zinc was not then employed, assume the latter to be 32.7. 
This weight of copper will be the equivalent (that of oxygen 
being 8). Look up the specific heat of copper (Appendix III), 
and use this and the equivalent observed to find the atomic 
weight (?). 
What other atomic weights could be measured on this plan? 
171. Reactions of Silver Salts. 
a. Take 1-2 c.c. of silver nitrate solution. Test its reaction 
towards litmus [R 647] (?). Is silver more or less active as a 
metallic element than copper? 
Add dilute hydrochloric acid until no further precipitation 
occurs (?). Filter, wash the precipitate with water, and place 
a small part of it in the sunlight (?). Reserve the rest for b, c, 
and d. 
Place a drop of silver nitrate solution on the skin, and examine 
after an hour (?). 
b. To a small part of the precipitate add ammonium hydrox- 
ide (?). What complex ion is formed? Now add dilute nitric 
acid in excess (?). Formulate the action of this acid. 
c. To another small part add sodium thiosulphate solution (?). 
Pass hydrogen sulphide (see /) through the mixture (?). Ex- 
plain both actions. 
d. Place the rest of the precipitate in a porcelain crucible, 142 
COPPER AND SILVER 
[§ 171 
put on it a piece of granulated zinc, and fill up with dilute sul- 
phuric acid. Stir from time to time (?). After an hour or two 
pour off the acid, take out any unchanged zinc, wash the pre- 
cipitate with water by decantation, add ammonium hydroxide, 
and filter. Find out whether any silver chloride had remained 
unchanged and so passed into the filtrate (171 6) (?). When 
the filter paper is dry, place the dark powder in a hollow on a 
stick of charcoal and melt it with the flame of the blast-lamp 
directed downward upon it (?). 
e. Dilute a few drops of silver nitrate solution and divide 
into two parts. To one add potassium bromide solution (?), 
and to the other potassium iodide solution (?). Add to each some 
ammonium hydroxide (?). Compare the rates of action with 
that on silver chloride (?). Arrange the three salts and ammonio- 
argentic-ion in the order of decreasing ability to give argentic- 
ion (?). Relate this order to that of solubility (Appendix IV). 
f. Dilute 2-3 drops of silver nitrate solution and lead in 
hydrogen sulphide (?). Is this action reversible, theoretically? 
Divide the product into two parts, and to one add dilute nitric 
acid (?). 
To the other part add potassium cyanide solution [Caution! 
Poison] (?). What is formed? * Could silver chloride be pre- 
cipitated from this solution (64 6)? Explain. 
g. To 1 c.c. of silver nitrate solution add a few drops of 
potassium dichromate solution (?). Test the solutions before (?) 
and after mixing (?) with Congo red paper [R 392]. (If the 
color of the dichromate obscures that of the Congo red, wash 
the test-paper with distilled water.) What product does this 
show? Make the equation accordingly. 
Note that chromic acid solution is deep red in color, and" as an 
acid is too feeble to affect this indicator. CHAPTER XXI. 
MAGNESIUM, ZINC, CADMIUM, MERCURY. 
172. Magnesium. Mix thoroughly in a mortar equal bulks 
of magnesium powder and powdered calcium carbonate. Put the 
mixture in a test-tube (it should fill about half an inch of the 
tube), fix the tube in a clamp on the stand, and heat the top 
layer in the Bunsen flame until the reaction begins. [Caution! 
Be careful to keep the tube directed away from the face during 
the heating.] Allow the test-tube to cool, add a little water, and 
then, slowly, an excess of concentrated hydrochloric acid (?). 
(If the tube has been broken, place the contents with the acid 
in a beaker.) Note the odor (?). What effect will the acid 
have upon any excess of either of the ingredients? The acid will 
also dissolve the oxides of magnesium and calcium formed by 
the action. When all action has ceased, filter and wash the black 
residue (?) with water. After drying this on the radiator or water 
bath, prove that it is carbon. 
This may be done by placing some of it in a dry test-tube, add- 
ing a pinch of potassium chlorate, heating in the Bunsen flame, 
and pouring the gas when it has cooled (close the tube with the 
thumb while waiting for this) into a test-tube containing 2 c.c. 
of limewater, and shaking (?). 
What is the reducing agent in this action? 
Examine the test-tube (?) and explain [R 630]. 
173. Properties of Magnesium Compounds. 
a. Try whether magnesium chloride dissolves completely in 
water (?). Test the solution with litmus and draw an in- 
ference (?). 
Heat some of the crystals strongly in a dry test-tube (?). 
Test the reaction towards litmus paper of the water which con- 
denses in the tube (?), and then remove the liquid from the 
sides of the tube with a piece of filter paper. Does the residue 
dissolve in water? Explain. 
b. To some diluted magnesium sulphate solution add ammo- 
nium hydroxide (?). Explain the result in terms of the ion- 
143 [§ 174 
144 
MAGNESIUM, ZINC, MERCURY 
product constant [R 711] (?). Now mix with some ammonium 
hydroxide several times its volume of ammonium chloride solu- 
tion (what effect will this have on the ionization of ammonium 
hydroxide? Would ammonium sulphate answer as well?), and 
then add the mixture to a new portion of magnesium sulphate 
solution (?). Explain in terms of the ion-product constant. 
To this combination of three solutions add sodium phosphate 
solution (see 120 c) (?). Explain the purpose of each ingredient. 
c. To a fresh portion of the diluted magnesium sulphate 
solution add ammonium carbonate solution, and warm (?). 
Repeat, adding excess of ammonium chloride solution to the 
magnesium sulphate solution before using the carbonate (?). 
Calcium-ion (158 d), strontium-ion (159 b), and barium-ion 
(160 6) were also precipitated by ammonium carbonate. Repeat 
these experiments with them, adding first excess of ammonium 
chloride solution (?). If you had a salt of magnesium mixed 
with a salt of one of those other metals, how should you proceed 
so as to precipitate a compound of the alkaline earth metal 
first and one of magnesium afterwards? 
Add two drops of hydrochloric acid (why?) to about 250 c.c. 
of the city water, evaporate to small bulk, and test it for calcium- 
ion and magnesium-ion. 
d. Pass hydrogen sulphide through magnesium sulphate 
solution (?). 
174. Reactions of Zinc Salts. Use diluted zinc sulphate 
solution. 
a. Test the solution with litmus paper (?). Explain (?). 
b. To a part of it add sodium carbonate solution (?). Bring 
the contents of the tube to the boiling-point, filter, and wash 
the precipitate with water. To a portion of the precipitate add 
an acid (?). Dry the rest of the precipitate for c. 
c. Heat the dried, basic zinc carbonate from b in a porcelain 
crucible to redness for a few minutes. Remove a small portion 
of the product and try the action of an acid upon it (?). If it 
effervesces, ignite for a longer time. What is the color of the 
product when hot, and when cold? Reserve for d. 
d. Moisten the residue from c with a few drops of a cobalt 
chloride solution and heat again (?). 
e. To another part of the zinc sulphate solution add a very 
little sodium hydroxide solution, and shake (?). Filter, sus- 
pend the precipitate in water, and divide into three parts. §176] 
MAGNESIUM, ZINC, MERCURY 
145 
To one add an excess of sodium hydroxide solution (?). Does 
this show zinc hydroxide to be basic, or acidic? 
To the second portion add dilute hydrochloric acid (?). What 
sort of hydroxide does it now seem to be? Explain [R 771] (?). 
To the third portion add ammonium hydroxide (?). What 
complex ion is formed [R 771]? 
f. To a third portion of zinc sulphate solution add ammo- 
nium sulphide solution (?). Filter, and wash the precipitate 
and filter-paper with water until no odor of hydrogen sulphide 
remains. To a part of the precipitate add a drop of hydrochloric 
acid (?). Odor? Preserve the rest of the precipitate for g. 
g. Roll up a small part of the filter paper from / (or 6) into 
a ball, and coil the platinum wire tightly round it. Roast the 
whole in the ,Bunsen flame (?). Moisten the ash with cobalt 
chloride solution and heat again (?). 
175. Relative Activity of Several Acids. In clean test-tubes 
place equal volumes of (1) zinc chloride, (2) zinc sulphate, and 
(3) zinc acetate solutions. Compare their reactions towards 
litmus and towards Congo red paper [R 392] (?). Into each 
pass hydrogen sulphide to saturation (test? Note 37, p. 79) (?). 
Are actions like this reversible, theoretically? The reverse 
action consists in the action of what acid upon what insoluble 
salt in each case? Will it be equal with different acids [R 774]? 
If not, the most active acid will have kept the most zinc in solu- 
tion and the least active the least. To ascertain how much zinc 
remains in each solution, filter the mixtures separately, and, 
after testing with Congo red paper (?), add ammonium hydroxide 
to each (?). The precipitates are zinc sulphide (why?). Com- 
pare the amounts (?). Infer the relative activities of the acids (?). 
Confirm the conclusion, roughly, by putting some of the 
precipitate into each of three test-tubes, treating directly with 
dilute hydrochloric, sulphuric, and acetic acids, of equivalent 
concentrations, and comparing the rates of action (?). 
Why was ammonium sulphide used in 174 f. 
176. Ionic Equilibrium. Take a larger amount of zinc sul- 
phate solution, and add sulphuric acid to it cautiously (only 
a few drops are required) until a sample just ceases to give any 
precipitate with hydrogen sulphide. Explain (?). To half of 
the mixture add much powdered, anhydrous sodium sulphate, 
stir until it has dissolved, and test a part with hydrogen sul- 
phide again (?). What effect must the great addition of sulphate- 146 
MAGNESIUM, ZINC, MERCURY 
[§ 181 
ion have upon the hydrogen-ion introduced by the sulphuric acid? 
Why is zinc sulphide now precipitated? 
To the other half of the mixture, add solid sodium acetate and 
shake until the latter has dissolved. Now lead hydrogen sul- 
phide into the liquid (?). Explain why zinc sulphide is now 
precipitated (?). 
177. Reactions of Cadmium Salts. Use diluted cadmium 
sulphate solution. 
a. Same as 174 e. Answer the same questions. 
b. Saturate with hydrogen sulphide (?). Is the action easily 
reversible? Add dilute hydrochloric acid (?). 
By what reactions could you distinguish between salts of 
magnesium, zinc, and cadmium? 
178. Unknown Substances. Apply to the instructor for three 
unknown substances. To identify the anions, follow the outline 
of work in 161. To identify the cations, employ the scheme 
commonly used in analysis [R 783]. Present to the instructor 
a logical and coherent, written report, as directed in 161. 
179. Mercurous Nitrate. Place about 10 g. of mercury with 
15 c.c. of diluted (1:1) nitric acid in a small beaker, and let the 
action go on for an hour. Stirring will cause crystallization. 
Dissolve the crystals in water to which a few drops of nitric acid 
have been added (why?). Use this solution in 181. 
180. Mercuric Nitrate. Boil some mercury or mercurous 
nitrate with excess of concentrated nitric acid. Evaporate 
[Hood] the solution on a water bath, moisten with nitric acid, 
and dry. 
181. Reactions of Salts of Mercury. Use diluted portions 
of mercurous nitrate solution and of a diluted solution of any 
mercuric salt, and add to each the following reagents. Compare 
the results in each case. 
a. Litmus paper (?). Explain (?). 
b. Dilute hydrochloric acid (?). Treat the precipitate, if 
there is any, with ammonium hydroxide [R 782] (?). 
c. Sodium hydroxide solution [R 779] (?). 
d. Ammonium hydroxide [R 781] (?). 
e. Hydrogen sulphide to saturation [R 780] (?). 
f. Potassium iodide solution (shake) until there is no further 
change (?). What complex ion is formed? Try an experiment 
to show that mercuric sulphide gives an even smaller concen- 
tration of mercuric-ion than does this complex ion (?), §182] 
MAGNESIUM, ZINC, MERCURY 
147 
g. Stannous chloride till there is no further change [R 778] (?). 
h. A clean piece of copper (?). Determine whether any 
copper goes into solution (?). Explain (?). 
i. Heat a little of a salt of mercury in a dry test-tube (?). 
j. How could you distinguish a solution of a mercurous and 
of a mercuric salt, respectively, from salts of silver, copper, 
magnesium, zinc, and cadmium? 
Do magnesium, zinc, cadmium, and mercury exhibit the prop- 
erties of typical metallic elements [R 645]? Explain (?). 
182. Concentration Cell. Suspend a rod of tin about 60 mm. 
long by a thread from one end, and hang it near the bottom of 
the graduated cylinder. Pour in through the dropping-funnel, 
which must reach the bottom of the cylinder, first water contain- 
ing 5 drops of dilute hydrochloric acid and then diluted (1:1) 
stannous chloride solution. Perform the operation with care, 
in such a way that the solutions do not mix, the dilute acid 
being finally uppermost, and that the surface at which they 
meet is near the middle of the rod of tin. If the second solution 
is permitted to carry air bubbles with i^, mixing will inevitably 
occur. Place the arrangement where it will not be disturbed, 
and examine from time to time (?). Explain [R 801]. CHAPTER XXII. 
ALUMINIUM, TIN, LEAD. 
183. Aluminium. 
a. Record here the action of aluminium on hydrochloric acid 
(18 a) and its degree of intensity (?). Try the action of the 
metal on dilute sulphuric (?) and dilute nitric acids (?). Com- 
pare and explain. 
b. Place some aluminium turnings with sodium hydroxide 
solution in a beaker (?). To ascertain whether anything has 
gone into solution, neutralize one-half of the liquid carefully 
with dilute hydrochloric acid (?). Test the precipitate by 
W(?). 
c. To the rest of the liquid from b add calcium chloride solu- 
tion (?). To what group of minerals do compounds allied to 
this belong [R 812]? 
184. Reactions of Aluminium Salts. Use portions of diluted 
aluminium sulphate solution. 
a. Test the solution with litmus paper (?). Explain (?). 
b. Add ammonium sulphide solution (?). Filter off the pre- 
cipitate, wash it until odorless (why?), and ascertain whether it 
is a sulphide or not (?). Preserve a part of it for f. 
c. Add sodium carbonate solution (?). Filter off the precip- 
itate, wash it until free from sodium carbonate (why?), and 
ascertain whether it is a carbonate or not (?). 
d. Add a little sodium hydroxide solution (?). Proceed as 
in 174 e, and answer the same questions (?). Explain the dif- 
ference in behavior observed (?). 
e. To a small portion of the suspension from d add sufficient 
sodium hydroxide solution to redissolve the precipitate. Then 
add excess of ammonium chloride solution, and boil (?). Ex- 
plain (?). 
f. Proceed as in 174 g with a small part of the filter paper 
from b (?) (or use the method in 174 d). 
185. Alum. Prepare warm, saturated solutions of hydrated 
aluminium sulphate and ammonium sulphate in approximately 
equimolecular proportions (calculate amounts required), mix 
148 § 189] 
ALUMINIUM, TIN, LEAD 
149 
them, and set aside (?). Obtain some large crystals by hanging 
a thread in the solution. Note the form and taste of the crys- 
tals (?). 
Dissolve one or two of the crystals, and ascertain by experi- 
ments selected from 184 whether the solution contains alu- 
minium-ion (?). Infer whether this is a double salt, or a salt 
giving a complex ion. 
186. Dyeing: Preparing the Cotton. In case the sizing has 
not been removed from the cotton cloth, boil seven pieces in 
50 c.c. of water containing 2 c.c. of concentrated hydrochloric 
acid. Rinse the goods in water, dip in 50 c.c. of cold water 
containing 0.5 c.c. of ammonium hydroxide, and rinse again. 
Use one piece in 187, two pieces in 189, two in 190 b and two 
in 190 c. 
187. Chrysophenin, a Direct Dye on Both Cotton and Wool. 
To 20 c.c. of water in the evaporating dish add 5 c.c. of the 
chrysophenin suspension* (shake the bottle) and 1 c.c. of so- 
dium sulphate solution,* and heat to boiling. 
Place in this bath one piece each of flannel and of cotton and 
keep them in motion with a glass rod for two minutes. Remove 
them and wash in running water (?). Is the dye fast to washing 
on both? What was the purpose of the sodium sulphate 
[R 821]? 
Smooth out the samples on a square of glass (or a bottle) to 
dry, and paste them in your note-book. 
188. A Lake. Take some cochineal solution, add to it a few 
drops of ammonium hydroxide, and shake. Then add 1 c.c. of 
aluminium sulphate solution, shake, and allow to stand (?). 
189. Alizarin, a Non-basic, Mordant Dye. In a test-tube 
dilute 2 c.c. of aluminium sulphate f solution with 10 c.c. of 
water, place in it a piece of cotton cloth and boil for two minutes. 
In a second test-tube dilute 1 c.c. of ammonium hydroxide 
with 10 c.c. of water. Wring the piece of cloth, place it in this 
solution and warm and shake for two minutes. Then wring 
the cloth, which is now mordanted with aluminium hydroxide. 
In the evaporating dish put 50 c.c. of water and 5 c.c. of 
the alizarin suspension! (shake the bottle). Place in this the 
* Chrysophenin suspension, 1 per cent. Sodium sulphate solution, 
8 g. Na2SO410H2O per 1 liter. 
f Aluminium sulphate, A-solution. Alizarin suspension, 5 g. of 20 per 
cent paste to 100 c.c. of water. 150 
ALUMINIUM, TIN, LEAD 
[§ 192 
piece of mordanted cloth and a piece of unmordanted cotton, 
and heat to boiling. Keep the pieces of cloth in motion for at 
least ten minutes. Finally, wash them in running water (?). 
Is the dye fast to washing on both? Why do they differ 
[R 820]? 
Dry the samples on glass and paste them into the note-book. 
190. Basic, Mordant Dyes. 
a. Measure into as many large test-tubes the following 
solutions: 
(1) 2 c.c. Malachite green (0.05%). 
(2) 2 c.c. Methyl violet (0.05%). 
(3) 2 c.c. Tannic acid (1%). 
(4) 2 c.c. Tartar emetic (1%). 
Add to each 20 c.c. of distilled water, and label and number 
the tubes. 
b. Place two pieces of cotton cloth in the evaporating dish, 
add the contents of (3), and keep at the boiling-point for five 
minutes. Wring the pieces of cloth and place them in (4), 
which is cold, and keep them in motion for five minutes. Then 
remove and wring the cloth, which is now mordanted with 
antimonyl tannate (?). 
c. The Dye without Mordant. Place in (1) and in (2) one 
piece each of unmordanted cloth, and keep each solution at the 
boiling-point for one minute. Wash the samples thoroughly 
in running water (?). Is the dye fast to washing? 
d. The Dye with Mordant. Now place in (1) and in (2) one 
piece each of the mordanted cotton from b, boil each for one 
minute, allow them to cool, and then wash the cloth thoroughly 
(?). Is the dye fast to washing? Dry all the samples on glass 
and mount in the note-book. 
191. Tin. Place some tin (gran.) in a test-tube with diluted 
nitric acid (1 acid: 10 Aq) and set aside. After 193, examine 
portions of the solution. Determine whether it contains a 
salt of ammonium (?), and explain. Determine whether it 
contains stannic-ion or stannous-ion (?). How does tin behave 
with concentrated nitric acid (110 d)? Explainthe difference. 
192. Halides of Tin. 
a. Stannous halide. Heat about 1 g. of tin with pure, con- 
centrated hydrochloric acid (see 18 a) (?). Let the action go 
on until the acid is nearly exhausted. Warm, to hasten the 
action, and make sure that an excess of tin is always present. § 195] 
ALUMINIUM, TIN, LEAD 
151 
Use the solution in b, and in 193. Proceed with later experi- 
ments until it is ready. 
b. Stannic halide [Hood]. To one-half of the solution from a 
add bromine-water until the color ceases to be destroyed, and 
drive off the excess of bromine by warming (?). Use this 
liquid in 193. 
193. Reactions of Stannous and Stannic Salts. In a, b, 
and c use a portion of each of the solutions from 192, after dilu- 
tion, with each reagent. Compare the two results in each case. 
a. Saturate (test?) each portion with hydrogen sulphide (?). 
To part of each product add dilute hydrochloric acid, to learn 
whether the action is easily reversible (?). Filter the remainder 
of each product, and treat the precipitates, separately, with 
warm yellow ammonium sulphide solution [R 828] (?). To 
the resulting liquids add dilute hydrochloric acid (?). Explain 
why both give the same product (?). What is the gas evolved? 
b. Add mercuric chloride solution, at first a little and then 
in excess, first to the stannic (?) and then to the stannous solu- 
tion (?). When the changes (two) in the latter are complete, 
boil, let the precipitate settle, filter the clear part of the liquid, 
and determine whether the tin in the filtrate is now stannous or 
stannic by adding a drop or two of bromine-water (see 192 b). 
c. Add to each portion a little sodium hydroxide solution (?). 
Proceed as in 174 e and answer the same questions (?). Ex- 
plain the difference, if any, in behavior observed. What other 
hydroxide resembles those of tin and zinc? 
d. Boil a small portion of the stannic solution with tin (gran.) 
for several minutes. Now add mercuric chloride solution (?) 
and compare with the results in b (?). Account for the change 
in the stannic-ion (?). What kind of chemical change was this? 
194. Unknowns. Apply to the instructor for two unknown 
substances. Identify them, and report the result, as directed 
in 178. 
195. Lead. 
a. Dissolve 1 g. of lead acetate in 20 c.c. of water, place in 
it several pieces of granulated zinc, and set aside for an hour or 
two. After 196 devise a way of precipitating any remaining 
lead-ion and showing the presence of zinc-ion in the solution (?). 
b. Wash some of the lead from a with distilled water, and see 
whether it is possible to get washings which show no reaction 
with hydrogen sulphide (?). Account for what you observe (?). 152 
ALUMINIUM, TIN, LEAD 
[§ 197 
196. Reactions of Lead Salts. Use diluted lead nitrate. 
a. Test with litmus paper (?). 
b. Saturate (test?) with hydrogen sulphide (?). Is the 
action easily reversed? 
c. Add dilute hydrochloric acid (?). Filter, dilute the fil- 
trate with 5-10 volumes of water, and saturate with hydrogen 
sulphide (?). Explain. What other chlorides are "insoluble"? 
d. Add sodium hydroxide (?), first a little, then in excess (?). 
What other hydroxides resemble this one? 
e. Add potassium iodide solution (?). Boil, filter, and ex- 
amine the filtrate (?). Infer a property of lead iodide (?). 
f. Potassium dichromate solution (?). Proceed as in 171 g (?). 
g. Dilute sulphuric acid (?). What sulphates are insoluble? 
197. Lead Dioxide. 
a. Warm and agitate 1 g. of minium with 5-6 c.c. of dilute 
nitric acid until it no longer changes in color (?). Dilute with 
water, and filter. Reserve the precipitate for b and c. Show 
by tests selected from 196 that lead-ion is present in the fil- 
trate. What theory of the nature of red lead is suggested by 
this action [R 832]? 
b. Treat a part of the precipitate from a with sodium hy- 
droxide solution (?). Record here the action of hydrochloric 
acid upon lead dioxide (39 a) and explain it (?). 
c. Allow the rest of the precipitate from a to dry, place it 
in an evaporating-dish, and direct upon it a stream of hydrogen 
sulphide (?). Explain (?). 
d. Do aluminium, tin, and lead exhibit the properties of 
typical metallic elements [R 645]? Explain (?). CHAPTER XXIII. 
ARSENIC, ANTIMONY, BISMUTH. 
198. Arsenic. 
a. Heat one particle of arsenic in a hard glass test-tube (?). 
b. Roast a particle of arsenic on a crucible lid (?). Note the 
behavior and odor (?). 
c. Mix a pinch of pulverized arsenic trioxide with wood 
charcoal (pulv.). Heat the mixture strongly in a dry test- 
tube (?). Compare result with a (?). 
d. Boil 0.5 g. of arsenic (pulv.) with excess of nitric acid 
[Hood] (?). Compare with 119 b. Use the solution for 201 e. 
199. Arsenic Trioxide and Arsenious Chloride. 
a. Boil 0.5 g. of arsenic trioxide with water (?). Test the 
solution with litmus (?). Now add sodium hydroxide solution, 
and boil (?). To what class of oxides does the trioxide appear 
to belong? Formulate the whole change. 
b. Boil 1 g. of the trioxide with 2-3 c.c. of concentrated 
hydrochloric acid (?). To what class of oxides does it appear 
now to belong? Formulate this change (?). Set aside and ex- 
amine later (?). What are the crystals [R 842]? Is this action 
reversible? Use the solution for c and 202. 
Is arsenic a typical metallic element? Is it a metal at all? 
Give reasons taken from a and b. 
c. Take a small part of the solution from b (setting aside 
the rest), dilute with water, and saturate wtih hydrogen sul- 
phide (?). Divide into two parts. With one, try whether the 
action is easily reversible (?). Filter the other and heat the 
precipitate with yellow ammonium sulphide solution (?). What 
other sulphide behaved in this way? Now add dilute hydro- 
chloric acid to the liquid (?). Explain (?). What is the gas 
evolved? 
200. Arsenites. Use portions of diluted potassium arsenite 
solution. 
a. Add silver nitrate solution (?), then ammonium hy- 
droxide (?). 
153 154 
ARSENIC, ANTIMONY, BISMUTH 
[§ 204 
b. Add cupric sulphate solution [R 745] (?). 
c. Test the solution with litmus (?). What substances must 
be present? Saturate with hydrogen sulphide (?). 
201. Arsenic Acid and Arsenates. For a, b, c, and d, use 
portions of diluted potassium arsenate solution. 
a. Add silver nitrate solution (?). Add now ammonium 
hydroxide (?). 
b. Add magnesia mixture (120 c) (?). Compare with 173 
&(?). 
c. Add to ammonium molybdate solution as in 119 c (?). 
d. Add 2-3 drops of dilute hydrochloric acid (?) and saturate 
with hydrogen sulphide (?). Now add excess of concentrated 
hydrochloric acid and saturate again (?), heating to assist the 
action. Explain (?). 
e. Neutralize the solution from 198 d with ammonium hy- 
droxide, avoiding excess, and use tests selected from a, b, and 
c(?). 
202. Arsine [Hood. Care! Poisonous gas]. Arrange a 
side-neck test-tube (or small flask), with safety and straight de- 
livery tubes and nozzle, to generate and burn hydrogen. Place 
in it a piece of chemically pure zinc, and add pure hydrochloric 
acid. When the air has been displaced (Care. Test?), light 
the gas and hold a crucible lid in the flame (?). If there is 
no deposit, add a drop or so of the solution of arsenic trichloride 
(199 b), observe the appearance of the flame, and obtain a de- 
posit on the crucible lid (?). What kind of chemical change 
takes place in the flame (see 80 5)? Heat the tube through 
which the gas passes to the nozzle, with a Bunsen flame 
(? Marsh's test). When these experiments are completed, fill 
the test-tube with water to stop the action. 
Apply bleaching powder solution (fresh) to the deposit (?). 
Can arsine be made according to the general method con- 
sidered in 130 6? What other hydrides behave like arsine when 
heated? 
203. Antimony. 
a, b. Proceed as in 198 a and b, using antimony (?). 
204. Antimony Trioxide. 
a. To obtain the trioxide, heat 2-3 g. of pulverized antimony 
with concentrated nitric acid in a small flask [Hood] (?). How 
should you determine whether the product was a nitrate or 
not? (?). What other metal behaved similarly when treated § 208] 
ARSENIC, ANTIMONY, BISMUTH 
155 
with nitric acid? Compare with arsenic (198 d and 201 e) (?). 
Dilute, filter, wash well [Note 39, p. 104], and use in b, c, d, 
and e. 
b. Boil a small part with water (?). Add sodium hydroxide 
solution, and boil (?). What kind of oxide is it? 
c. Boil a small part with hydrochloric acid (?). What kind 
of oxide is it? 
d. Boil a part with an equal amount of potassium-hydrogen 
tartrate in 5-6 c.c. of water (?). Filter, and set the filtrate 
aside (?). What are the crystals? To answer this question, 
dissolve some potassium-hydrogen tartrate and test the solu- 
tion with litmus (?). Later, dissolve some of the crystalline 
product in warm water and test with litmus (?). Inference (?). 
205. Antimony Trichloride and Trisulphide. 
a. Treat about 0.5 g. of antimony trichloride with water (?), 
and test the liquid with litmus paper (?). Add more water, 
warm, and ascertain whether the action is reversible by adding 
drop by drop (shake between drops) concentrated hydrochloric 
acid (?). When the liquid has become clear add a large amount 
of water (?). What law is illustrated? Finally, add concen- 
trated hydrochloric acid again (?), and use the solution in b. 
How does this action differ from that of water upon phos- 
phorus trichloride (121 b) and upon arsenic trichloride [R 842]? 
What is the significance of this difference? 
b. Dilute the liquid from a, saturate with hydrogen sulphide 
(?), and proceed as in 199 c (?). Answer the same questions. 
206. Stibine. Repeat 202, using antimony trichloride (?). 
207. Bismuth. Prepare a match (or splinter of wood) as in 
94, and proceed as in 166/, using any bismuth salt (?). What 
metals are obtainable in this precise way? Could zinc, mercury, 
silver, and aluminium be so obtained? Explain (?). 
208. Compounds of Bismuth. 
a. Warm about 1 g. of bismuth with 8-10 c.c. of diluted 
(1 :1) nitric acid (?). Concentrate to 3 c.c. and set aside 
[R 849] (?). Compare this result with arsenic (198 d) and anti- 
mony (204 d), and interpret (?). 
b. Proceed as in 205 a (first par.), using bismuth nitrate (or 
the product from d) and nitric acid, instead of the salt and 
acid there employed (?). 
c. Take 1-2 c.c. of bismuth nitrate solution, dilute it, and 
clear up with nitric acid if necessary. Saturate a part with 156 
ARSENIC, ANTIMONY, BISMUTH 
[§ 209 
hydrogen sulphide (?), and proceed as in 199 c (?). Compare 
with the sulphides of arsenic and antimony (?). 
d. To the remainder of the solution of bismuth nitrate add 
sodium hydroxide (?), at first a little, and then in excess (?). 
Compare this hydroxide with the oxides of arsenic (199 a) (?) 
and of antimony (204 6) (?). 
Filter off the precipitate, ignite it in a porcelain crucible, 
and note the color (?) when hot (?) and when cold (?). 
e. Do arsenic, antimony, and bismuth exhibit the proper- 
ties of typical metallic elements? If not, in what respects do 
they fail to do so? 
209. Unknowns. Apply to the instructor for two unknown 
substances. Identify them, and report the result, as directed 
in 161 and 178. Do not use Marsh's test for arsenic. CHAPTER XXIV. 
CHROMIUM, MANGANESE. 
210. Chromates. Melt 5 g. of potassium carbonate with 
equal amounts of potassium hydroxide (omit this from the 
equation) and potassium nitrate (include only oxygen, from this, 
in the equation) at a low temperature in an iron crucible [Store- 
room] and stir in (use the reverse end of a file) 5 g. of powdered 
chromite. Heat strongly [Blast-lamp] for several minutes (?). 
When the mass has cooled dissolve it in a little boiling water. 
Filter, and add dilute nitric acid to the solution until it is acid (?). 
Note the change in color (?). 
211. Dichromates and Chromates. Take some potassium 
dichromate solution and run into it potassium hydroxide solu- 
tion from a burette till the change in color is complete. A 
test-tube trial will show the tint to be reached. Concentrate 
the solution and allow it to crystallize (?). What kind of salt 
(neutral, acid, basic, double, or complex) is potassium dichro- 
mate, essentially? What are the colors of dichromate-ion and 
of chromate-ion? 
212. Reactions of Chromates. For a, b, c, use diluted po- 
tassium chromate solution. What are the ions in the solution? 
a. Acidify a part of the solution with dilute sulphuric acid (?). 
Concentrate and set aside to crystallize (?). 
b. Recall the actions of hydrogen sulphide (81 e), of sulphurous 
acid (91 J), and of hydrogen peroxide (67 /), on such an acid 
solution (?). 
c. Add lead nitrate and barium chloride solutions to sepa- 
rate portions (?). 
d. Repeat c with potassium dichromate solution (?). Com- 
pare the results and explain (?). 
213. Chromic Anhydride. Make a cold saturated solution of 
5 g. of sodium dichromate, add to it two volumes of concen- 
trated sulphuric acid in a beaker, and cool (?). Filter through 
a small plug of asbestos, and dry the precipitate by smearing 
it on a piece of broken bisque plate [Storeroom], 
214. Chromic Oxide. Pulverize potassium dichromate (10 
g.) thoroughly with one-fifth its weight of sulphur, and heat 
157 158 
CHROMIUM, MANGANESE 
[§ 217 
with the blast-lamp in a porcelain crucible for fifteen minutes. 
Grind up the resulting mass in a mortar with water, filter, 
wash the green residue (?), and dry it on a radiator for use 
in 215. Test the filtrate for potassium sulphate (?). 
Make a borax bead, dissolve a particle of chromic oxide in 
it, and note the effects of the oxidizing and reducing flames 
upon it (?). All chromium compounds give the same result. If 
chromic sulphate had been used, what would have been the 
nature of the chemical action? 
215. Chromic Chloride. Mix the chromic oxide prepared in 
214, with one-third its weight of pulverized wood charcoal, 
make into a stiff paste with some starch, and mold the mixture 
into little pellets of the size of peas. Cover these completely 
with a layer of charcoal powder (why?) in a closed crucible, 
dry them by heating gently with the Bunsen flame, and let them 
cool before exposing them to the air (why?). Place them in a 
piece of hard glass tubing. Then connect with a chlorine 
apparatus, and, when the chlorine gas has reached the pellets 
and completely displaced the air (why?), heat strongly with a 
blast-lamp. Conduct any superfluous chlorine into a test- 
tube filled with sodium hydroxide. Describe the substance 
which is formed, and try its solubility in water and acids 
(?)• 
216. Chrome-Alum. Dissolve 10 g. potassium dichromate in 
water, add the amount (calculated) of sulphuric acid necessary 
to form potassium sulphate and chromium sulphate, warm and 
add alcohol (7-10 c.c.), a little at a time, until the yellow color 
has entirely given place to a pure, bright green. The action 
takes some time to reach completion. Note the odor (?). Set 
the greater part of the solution aside to evaporate spontane- 
ously. Concentrate the smaller portion on the water bath until 
crystals appear. Examine the form and color of the crystals 
from both portions (?). What is the color of their solution in 
water? What is the color of chromic-ion? 
217. Reactions of Chromic Salts. Use a solution of chrome- 
alum. What are the ions in the solution? 
a. Boil a portion for some time [R 862]. 
b. To another portion add sodium hydroxide solution, at 
first a little (?), then in excess (?). Boil [R 861]. 
c. Add ammonium sulphide (?). Filter off the precipitate, 
wash it until odorless, and determine whether it is a sulphide (?). § 220] 
CHROMIUM, MANGANESE 
159 
d. Add excess of sodium hydroxide solution and then a large 
volume of bromine-water, and heat (?). Try another portion, 
using lead dioxide instead of bromine (?). Infer the nature of 
the action from the change in color (?). 
218. Manganates and Permanganates. 
a. Fuse a mixture of 5 g. of potassium hydroxide, 2.5 g. po- 
tassium chlorate (include only the oxygen, from this, in the equa- 
tion), and 5 g. finely powdered manganese dioxide, at a red 
heat, in an iron crucible [Storeroom], stirring with the reverse 
end of a file, until effervescence ceases (?). Add the last ingre- 
dient gradually. Treat the mass with a small amount of cold 
water, decant the clear liquid away from the precipitate, and 
use it in b, c, and d. What is the color of manganate-ion? 
b. Dilute a part of the clear green solution with a very large 
amount of water in a beaker (?). If no change should occur, 
pass carbon dioxide into the diluted solution (?). What is the 
color of permanganate-ion? How does this substance differ 
from manganate-ion in respect to composition, valence, and 
physical properties? 
c. Add a few drops of alcohol, and warm (?). 
d. To the rest add a boiling solution of oxalic acid (?). 
e. Repeat c and d with potassium permanganate solution, 
acidified by adding two or three times its volume of dilute sul- 
phuric acid (?). 
/. Recall the actions of hydrogen peroxide (67 c), hydrogen 
sulphide (81 /), and sulphurous acid (91 g) on acidified potas- 
sium permanganate solution (?). 
219. Reactions of Manganous Salts. Use any manganous 
salt. What is the color of manganous-ion? 
a. Borax bead in the oxidizing (?) and reducing (?) flames. 
b. Bead of a mixture of sodium carbonate and sodium nitrate 
on a platinum wire with any manganese compound (?). 
c. To a diluted solution of a manganous salt, add ammo- 
nium sulphide (?). Is the product a sulphide? 
d. To another portion add sodium hydroxide (?). Divide 
into two parts. Shake one with air (?). To the other add 
bromine-water, and warm (?). 
220. Unknowns. Apply to the instructor for two unknown 
substances. Identify them, and report the result, as directed in 
161 and 178. CHAPTER XXV. 
IRON, COBALT, NICKEL. 
221. Iron. Recall the preparation of iron from an oxide 
(22), and the action of the metal on dilute acids (18 a) (?). 
222. Reactions of Ferrous and Ferric Salts: I. 
a. Borax bead with any compound of iron (use the oxide) in 
the reducing (?) and oxidizing (?) flames. 
b. Recall the action of heat upon ferric nitrate (42 a) and 
upon ferric sulphate (90) (?). 
Prepare a dilute solution of ferrous-ammonium sulphate [Note 
38, p. 80]. Dilute some ferric chloride solution [Note 41, p. 
128]. Use portions of these solutions, and add to each the 
following reagents. Compare the results in each case. 
c. Ammonium hydroxide (?). Shake with air (?). 
d. Potassium ferrocyanide solution (?). 
e. Potassium ferricyanide solution (?) and add much water. 
f. Ammonium thiocyanate solution (?). 
223. Reactions of Ferrous and Ferric Salts: II. Reductions 
and Oxidations. Use diluted ferrous-ammonium sulphate and 
diluted ferric chloride solutions. 
a. To portions of each solution add ammonium sulphide 
solution (?). Ascertain in each case whether the action is 
easily reversible (?). Explain the behavior of the ferric chlo- 
ride solution [R 897] (?). How could you determine whether 
the free sulphur was formed before or after the acidification? 
b. To portions of each solution add potassium iodide solu- 
tion (?). To a little starch emulsion add a few drops of the 
ferric-potassium-iodide mixture (?). 
c. Saturate (test?) a portion of the ferrous solution with 
hydrogen sulphide (?). Explain in terms of the ion-product 
constant (?). Now add ammonium hydroxide (?). Filter. 
Wash the precipitate until odorless, and determine whether it 
is a sulphide or hydroxide (?). Explain in terms of the ion- 
product constant (?). 
d. Saturate (test?) a portion of the ferric solution with hy- 
160 | 226] 
IRON, COBALT, NICKEL 
161 
drogen sulphide (?). Filter. What is the precipitate (test?)? 
Examine the clear filtrate, and determine, by means of tests 
from 222 d, e, and /, whether ferric-ion or ferrous-ion is pres- 
ent (?). Formulate the action of the hydrogen sulphide (?). 
e. Boil a portion of the ferric solution with excess of pul- 
verized iron for several minutes. Filter, and at once apply to 
part of the clear filtrate (color?) tests selected from 222 d, e, and/ 
(?). Formulate the action of the iron. 
/. To 2 c.c. of potassium permanganate solution add a large 
excess of dilute sulphuric acid (?). Add this mixture drop by 
drop to 5 c.c of a dilute solution of ferrous-ammonium sulphate 
until the pink color is permanent [R 882] (?). Apply to this 
liquid tests from 222 d, e, and / (?). Formulate the action in 
terms of ions alone. Which kinds of ionic chemical change have 
been illustrated here? How could this action be used for esti- 
mating iron? 
What other oxidizing agents convert ferrous into ferric salts 
(see 107 /)? 
224. Hydrolysis. Dissolve 0.5 g. each of ferric sulphate and 
ferrous-ammonium sulphate separately in water, and warm 
very slightly. Observe the tints by looking downward through 
the solutions at a piece of white paper (?). Test each solution 
with Congo red paper, compare (?), and interpret the results. 
Now add some pure sulphuric acid to each and observe the tints 
again (?). Explain (?). What are the colors of ferrous-ion and 
ferric-ion, respectively? Which of these allotropic forms of 
the element is more typically metallic? 
225. Iron-Ammonium Alum. 
a. Weigh 6 g. of ferric sulphate into an evaporating-dish. 
Weigh out an equimolecular quantity (calculate) of ammo- 
nium sulphate. Dissolve the salts separately, each in the mini- 
mum amount of boiling water, mix the solutions, and set aside 
(?). Describe the crystals (?). Collect them upon a filter, 
wash them free from the mother-liquor, and dry with filter paper. 
b. Ascertain (see 222 c, d, e) whether iron-alum is a double 
salt, or a salt of a complex acid (?). 
226. Ferrocyanides and Ferricyanides. Use diluted potas- 
sium ferrocyanide solution. 
a. Add ammonium hydroxide (?) and compare with 222 c (?). 
b. Add ammonium sulphide solution and compare with 
223 a (?). Is ferrous-ion present? 162 
IRON, COBALT, NICKEL 
[§229 
c. Add bromine-water (shake) in excess, and boil off the 
superfluous bromine. To a part of the liquid add ferric chloride 
solution (see 222 d and e) (?). 
d. To the rest of the liquid from c apply the tests in 222 c 
and / (?). Is ferric-ion present? 
227. Reactions of Cobalt Salts. For b, c, and d use diluted 
cobalt chloride solution. 
a. Borax bead in oxidizing (?) and reducing (?) flames. 
b. Sodium hydroxide solution, first a little (?), then in excess, 
and warm (?). Shake with air (?). 
c. Ammonium sulphide solution (?). 
d. Potassium cyanide solution, first two drops (?), and then 
in excess (?). Boil the mixture. Add bromine-water (or 
chlorine-water, or bleaching powder) and then sodium hydrox- 
ide solution (?). Compare this with 228 d (?). 
228. Reactions of Nickel Salts. For b and c use diluted 
nickel sulphate solution. 
a, b, c, d. Same as in 227. 
229. Unknowns. Apply to the instructor for two unknown 
substances. Identify them, and report the result, as directed in 
161 and 178. APPENDIX. 
I. Correction of Barometric Readings. 
To reduce the reading taken at room temperature (Temp.) 
to the corresponding height of a column of mercury at 0°, sub- 
tract the proper number in the second column (Corr'n) from 
the actual reading in millimeters. [See Note 32, p. 21.] 
Temp. 
Corr'n. 
Temp. 
Corr'n. 
Temp. 
Corr'n. 
12 
1.6 
17 
2.2 
23 
3.0 
13 
1.7 
18.5 
2.4 
24.5 
3.2 
14 
1.8 
20 
2.6 
25 
3.3 
15 
2.0 
21.5 
2.8 
26 
3.4 
Temp. 
Press. 
Temp. 
Press. 
Temp. 
Press. 
0° 
4.6 
16° 
13.5 
26° 
25.1 
5 
6.5 
17 
14.4 
27 
26.5 
8 
8.0 
18 
15.4 
28 
28.1 
9 
8.6 
19 
16.3 
29 
29.8 
10 
9.2 
20 
17.4 
30 
31.5 
11 
9.8 
21 
18.5 
31 
33.4 
12 
10.5 
22 
19.7 
32 
35.4 
13 
11.2 
23 
20.9 
33 
37.4 
14 
11.9 
24 
22.2 
34 
39.6 
15 
12.7 
25 
23.6 
100 
760.0 
II. Tension of Aqueous Vapor in Millimeters. 
III. Specific Heats of Metals. 
Aluminium 0.214 Iron 0.114 Magnesium 0.250 
Copper 0.095 Lead 0.031 Zinc 0.095 
163 164 
APPENDIX 
K 
Na 
Li 
Ag 
T1 
Ba 
Sr 
Ca 
Mg 
Zn 
Pb 
Cl 
32.95 
3.9 
35.86 
5.42 
77.79 
13.3 
0.0a13 
0.069 
0.3 
0.013 
37.24 
1.7 
51.09 
3.0 
73.19 
5.4 
55.81 
5.1 
203.9 
9.2 
1.49 
0.05 
Br 
65.86 
4.6 
88.76 
6.9 
168.7 
12.6 
0.04l 
0.0,6 
0.042 
0.0s15 
103.6 
2.9 
96.52 
3.4 
143.3 
5.2 
103.1 
4.6 
478.2 
9.8 
0.598 
0.02 
I 
137.5 
6.0 
177.9 
8.1 
161.5 
8.5 
0.0,35 
O.Ojl 
0.006 
0.0,17 
201.4 
3.8 
169.2 
3.9 
200 
4.8 
148.2 
4.1 
419 
6.9 
0.08 
0.0,2 
F 
92.56 
12.4 
4.44 
1.06 
0.27 
0.11 
195.4 
13.5 
72.05 
3 
0.16 
0.0a92 
0.012 
0.001 
0.0016 
0.0,2 
0.0087 
0.0,14 
0.005 
0.0,5 
0.06 
0.002 
NOa 
30.34 
2.6 
83.97 
7.4 
71.43 
7.3 
213.4 
8.4 
8.91 
0.35 
8.74 
0.33 
66.27 
2.7 
121.8 
5.2 
74.31 
4.0 
117.8 
4.7 
If 
C103 
6.6 
0.52 
97.16 
6.4 
313.4 
15.3 
12.25 
0.6 
3.69 
0.13 
35.42 
1.1 
174.9 
4.6 
179.3 
5.3 
126.4 
4.7 
183.9 
5.3 
150.6 
3.16 
BrOa 
6.38 
0.38 
36.67 
2.2 
152.5 
8.20 
0.59 
0.025 
0.30 
0.009 
0.8 
0.02 
30.0 
0.9 
85.17 
2.3 
42.86 
1.5 
58.43 
1.8 
1.3 
0.03 
ioa 
7.62 
0.35 
8.33 
0.4 
80.43 
3.84 
0.004 
0.0314 
0.059 
0.0316 
0.05 
0.001 
0.25 
0.0357 
0.25 
0.007 
6.87 
0.26 
0.83 
0.02 
0.002 
0.0*3 
OH 
142.9 
18 
116.4 
21. 
12.04 
5.0 
0.01 
0.001 
40.04 
1.76 
3.7 
0.22 
0.77 
0.063 
0.17 
0.02 
0.001 
0.0,2 
0.0,5 
0.0*5 
0.01 
0.0,4 
SO* 
11.11 
0.62 
16.83 
1.15 
35.64 
2.8 
0.55 
0.020 
4.74 
0.09 
0.0323 
0.0*10 
0.011 
0.0,6 
0.20 
0.015 
35.43 
2.8 
53.12 
3.1 
0.0041 
0.0,13 
GrO* 
63.1 
2.7 
61.21 
3.30 
111.6 
6.5 
0.0025 
0.0315 
0.006 
0.03l 
0.0,35 
0.0*14 
0.12 
0.006 
0.4 
0.03 
73.0 
4.3 
. . . 
0.0*2 
0.0,5 
CaO* 
30.27 
1.6 
3.34 
0.24 
7.22 
0.69 
0.0034 
O.O317 
1.48 
0.030 
0.0085 
0.0338 
0.0046 
0.0a26 
0.0,55 
0.0*43 
0.03 
0.0027 
0.0364 
0.0*4 
0.0,16 
0.0,54 
cos 
108.0 
5.9 
19.39 
1.8 
1.3 
0.17 
0.003 
0.03l 
4.95 
0.10 
0.0023 
0.03ll 
0.0011 
0.0*7 
0.0013 
0.0,13 
0.1 
0.01 
0.004? 
0.0,3? 
0.0,1 
0.0*3 
IV. Solubilities of Bases and Salts in Water at 18°. 
The upper number in. each square gives the number of grams of the 
anhydrous salt held in solution by 100 c.c. of water. The lower number is 
the molar solubility, i.e., the number of moles contained in one liter of the 
saturated solution. APPENDIX V 
165 
Concentration 
Temperature 166 
APPENDIX 
VI. Degree of Ionization of lonogens. 
Except where otherwise specified, the figures give the fraction 
ionized in a deci-normal, aqueous solution (usually at 18°). Sub- 
traction of the figures from the unity gives the extent to which 
the ions will unite when brought together in normal concen- 
tration. At greater dilutions the ionization is greater and the 
union of ions less. 
Acids. 
HNO3 0.92 
HNO3 (cone.) 0.09 
HC1 0.92 
HC1 (cone.) 0.13 
HCl(A/2) 0.85 
H2SO4 0.61 
H2SO4 (cone.) 0.01 
HBr (N/2) 0.90 
HI (2V/2) 0.90 
HC103(A/2) 0.88 
HMnO4 (N/2) 0.93 
H.H2PO4 (JV/2) 0.27 
H.HC2O4 0.50 
H.HC4H4O6 0.08 
H.C2H3O2(A0 0.024 
H.C2H3O2 0.013 
H.HCO3(A/10) 0.0217 
H.HCO3(^/25) 0.0221 
H.HS(^/10) 0.037 
H.H2BO3 (N/IO) 0.03l 
HNC(A710) 0.03l 
HOH 0.06l 
Bases. 
KOH 0.91 
NaOH 0.91 
Ba(OH)2 0.77 
NH4OH 0.013 
Ca(OH)2 (2V/64) 0.90 
Sr(OH)2 (2V/64) 0.93 
Ba(OH)2 (y/64) 0.92 
AgOH (N/1783) 0.39 
HOH 0.06l 
Salts. 
KC1 0.86 
KC1O3 0.83 
KNO3 0.83 
K2SO4 0.72 
K2CO3 0.71 
KMnO4(2V/32) 0.92 
K2Cr2O7 (2V/32) 0.94 
NH4C1 0.85 
NaCl 0.84 
Na2SO4 0.70 
Na2CO3 0.71 
Na.HCO3 0.78 
Na2.HPO4 0.73 
N aC 2H3O2 0.79 
Na2C4H40s 0.69 
BaCl2 0.77 
CaSO4 (2V/100) 0.64 
CuSO4 0.39 
AgNO3 0.81 
ZnCl2 0.73 
ZnSO4 0.40 
HgCl2 (<0.01) APPENDIX 
167 
VII. Lists of Apparatus. 
1. Equipment of Laboratory. These articles are for com- 
mon use. Those marked * should be fixed in their places, so that 
they cannot be removed. The articles in this list, for the care 
of which no individual is responsible, should be as few as 
possible. 
Balances 1 
*Barometer (with thermometer) 
•Blast-lamps and bellows (or air supply) 
•Burners, fish-tail 
Conductivity apparatus, 68 
•Cork-press 
•Iron mortar and pestle 
Jars for refuse 
•Lens (on light chain) or microscope 
Radiators or drying oven 
*Roll of paper, smooth, colored2 
*Scales and weights 3 
Spectroscope (Browning's, direct vi- 
sion, English make) (Instructor] 
Tripod for each blast-lamp 
2. Supply Room. These articles are given out at the supply 
room when needed. The student who obtains one of them leaves 
a signed receipt, and is held responsible for the safe return of 
the article. 
Supply of all apparatus in Lists 3 and 4, 
to replace breakage 
Articles, if any, which may be omitted 
from Lists 3 and 4 
Apparatus for making sulphuric acid, 
viz., distilling flask with bent neck, 
Chapman pump, rubber connections 
and screw clamp, Exp. 87 
Bisque plates, 213 
Bottles, square, 50 c.c.. 139 
Condensers, with rubber tubing and uni- 
versal clamp and holder, 59, 133 a 
Distilling flasks, 30 c.c., 59, 106, 133 a 
Electrolytic cells, 68 
Graduated flasks (100 c.c., 500 c.c.), 
147 6 
Iron crucibles, 210, 218 a 
Lead dishes, 61 
Retorts, 100 c.c., 106 a 
Round bottom flasks, 250 c.c., 50, 127 
Screw clamps, 50, 100 
U-tubes, 155 mm., 54 6, 58 b 
3. Individual Outfit: Non-returnable. A copy of this list 
accompanies each outfit and is checked by the student. 
1 Clay triangle 
Copper wire, No. 22, 10 ft. 
25 Corks, assorted, small 
Dropper 107 d 
1 File, rat-tail, 6 in. 
1 File, triangular, 6 in. 
Filter paper, pkg., 11 cm. 
Gas tubing, 2 ft. 
Glass rod, 4 mm., 2.5 ft. 
Glass tubing, 6 mm., 5 ft.4 
1 Horn-pan balance, 6.5 in. beam 
1 Litmus paper, box, both colors, 100 
strips 
Parchment paper, pkg., 100 sheets 8 
Platinum wire, 3 in., No. 28 
2 Rubber stoppers, 1-hole, No. 0 
1 Rubber stopper, 2-hole, No. 6 
Rubber tubing, 1 ft. & in. 
1 Sand bath, 5 in. 
1 Sponge 
1 Test-tube brush, small 
1 Test-tube holder 
1 Towel (or muslin) 
1 Weights, set, 10 mgm. to 50 g. 
1 Wire gauze, 4 X 4 in. 
1 Student balance, Varsity model: Becker's Sons, Rotterdam. 
2 To prevent use for writing. 
3 Harvard trip scales, with rider (0-5 g.) to avoid loss of small weights, and 
weights (5 g.-1000 g.). A small platform spring balance (letter balance form), 
0-100 g. grad, in -J g., for measuring chemicals, in case horn-pan balances are not 
included in the individual outfits (see below). 
4 Stems of dropping funnel, thistle tube, and thermometer are of same diameter 
(6 mm.). This saves boring fresh corks, and thus avoids waste of time and supplies. 
6 Substitute for paper in list No. 1. 168 
APPENDIX 
4. Individual Outfit: Returnable. A copy of this list ac- 
companies each outfit and is checked by the student. A receipt 
for the outfit is left at the supply room, and the student is then 
held responsible for the return or replacement of every article 
upon the list. Articles marked * may be transferred to List II 
or even to List I. 
1 Boat, pore., 6 cm. 
1 Bridge, galv. iron 1 
1 Bunsen burner 
1 Burette clamp 
1 Cork borer, with rod, 5 mm.2 
1 Crucible tongs 
1 Deflagrating spoon, 13 mm. bowl 
1 Funnel support, two holes 
1 Iron stand, small 
2 Iron rings, two sizes 
1 Pinch clamp 
1 Spatula (horn or glass) 
1 Test-tube rack 
5 Beakers, nest, tall form, no lip Nos. 0, 
1, 2, 3, 4 
1 Bottle, special, 32 oz.3 
1 Bottle, special, 4 oz.3 
4 Bottles, wide mouth, 250 c.c. 
1 Burette, plain, 50 c.c. 
1 Crucible, porcelain, No. 6 
1 Cylinder, graduated, 100 c.c. 
1 Dropping funnel, 60 c.c. stem, 6 mm.4 
1 Evaporating dish, 5.5 cm. 
1 Evaporating dish, 7 cm. 
1 Evaporating dish, 8 cm. 
1 Flask, wide mouth, 125 c.c. 
1 Flask, wide mouth, 250 c.c. 
1 Flask, 500 c.c., with cork 
2 Funnels, 7.5 cm., short stem 
4 Glass squares, 5X5 cm. 
1 Mortar, 10 cm., and pestle 
1 * Pneumatic trough1 
1 Sink tube, brass1 
12 Test-tubes, 4 X 0.5 ins. 
12 Test-tubes, 6 X 0.67 ins. 
1 Test-tube, 6X1 ins. 
2 Test-tubes, hard glass, 7 X 0.67 ins. 
1 Test-tube, side-neck 
1 * Thermometer, stem 6 mm. 
1 Thistle safety tube, stem 6 mm. 
1 Tube, hard glass, 1 X 0.67 in. 
1 U-tube, with side tubes, 6 ins. 
1 Watch-glass, 2 ins. 
1 Watch-glass, 3.75 ins. 
1 Watch-glass, 4.5 ins. 
1 Wing top for burner 
VIII. List of Chemicals. 
All chemically pure, excepting where otherwise stated. 
After omissions, if any have been determined upon, the sub- 
stances (excepting those marked Cal.) are numbered consecu- 
tively and, if a side-shelf is used, their bottles and places on 
the shelves are numbered to correspond. 
(Spec.) indicates a small amount, or specimen, of the dry 
substance. These substances are used only in solution. 
Cal. indicates one of the substances in the calendar which 
are set out only when needed, and then on a special shelf. This 
mark appears also upon the bottle, taking the place of the serial 
number. 
1 Earthenware vessels, ' gallon milk pans, for which bridges of galvanized iron 
can be made, are inexpensive and last longer than tin troughs. The sink, if in the 
desk, can be provided with a tube to slip over the exit, and be used for collecting 
gases. 
2 Cork borers, if supplied for common use, are abused and soon become worth- 
less. One size suffices. 
3 Mouth to fit No. 6 stopper. 
4 This dropping funnel is indispensable only in experiments 54 b and 155, though 
very useful in many others. APPENDIX 
169 
Numbers in heavy type (e.g. 20) appear opposite substances 
which are used in only that one experiment. Omission of the 
one experiment permits removal of the substance from the list. 
Concentration, in case of a solution, is given as N, i N, etc., 
to assist students in using suitable proportions in a rational way. 
The number in parenthesis following the concentration is the 
weight of the substance required, with water, to make one liter 
of the solution. Sat. = saturated. Excepting where a formula 
is given, the calculation assumes the use of the commonest 
form, often a hydrated one. 
* Rubber stoppers, the rest glass. 
The labels should bear the name of the substance and all the 
data mentioned above. Thus both the student and the person 
who prepares the solution are fully informed as to the nature 
of the contents. 
Solids. 
1. Acid, boric (spec.) 
2. oxalic, com'l 
oxalic Cal., 147 b 
3. tartaric (spec.) 
Albumin, bird. Cal., 118 c, 120 d 
4. Aluminium, filings 
5. oxide, purif., 22 
6. sulphate, hydrated 
7. Ammonium carbonate, 152 
8. chloride, com'l 
9. nitrate, 111 a 
10. molybdate (spec.) 
11. oxalate (spec.) 
12. phosphate, 151 a 
13. sulphate 
14. thiocyanate (spec.) 
15. Antimony, com'l 
16. trichloride, 205 a 
Apple, slices, Cal., 91 h 
17. Arsenic, gran., 198 
18. trioxide, pulv., com'l, 139, 
198 c, 199 a 
19. Asbestos, short fiber, 41, 87, 213 
20. Barium chloride, com'l 
21. hydroxide (spec.) 
22. oxide, purif., 24 
23. peroxide, anhyd. 
24. Bismuth, com'l, 208 a 
25. nitrate 
26. Bleaching powder 
27. Cadmium sulphate (spec.) 
28. Calcium carbide, 130 a 
29. Calcium carbonate, purif., pulv., 
29 a, 172 
30. Calcium carbonate [Marble], gran. 
4 mm. 
31. chloride, gran. 
32. fluoride, pulv. 
33. oxide [Quicklime] 
34. phosphide, 117 
35. sulphate, pulv., 29 a, 159 d 
36. sulphate [Gypsum], transp. 
cryst., 26 
37. Calico, colored 
38. Charcoal, animal, pulv., 135 c 
39. wood, pulv. 
40. wood, splinters 6 X 6 X 50 mm. 
41. Chromite, pulv., 210 
42. Chromium-potassium sulphate 
[Chrome-alum ] 
Cloth, cotton, white, Cal., 186 
43. Coal, bituminous, 136 
44. Cobalt chloride 
45. Cochineal (spec.) 
46. Congo red paper 
47. Copper, foil, 79 a 
48. turnings 
49. Cupric bromide, 70 
50. chloride, 70 b, 162 a 
oxide, gran. Cal., 41] 
51. oxide, pulv. 
52. sulphate, hydrated 
53. Fat, tallow, 28 b, 138 a 
54. Ferric chloride (spec.) 
55. Ferric oxide, com'l, 22, 140 b 
56. Ferric sulphate 
57. Ferrous-ammonium sulphate 
58. Ferrous sulphide, gran. 4 mm., 
80 a, b 
59. Gelatine, 104 c 
60. Gunpowder, 9 c 
61. Iodine 
62. Iron, filings 
63. Iron, nails washed with gasoline, 
72 c, d 
64. Iron, pulv., 79 6, 223 e 
65. Iron pyrites, gran. 4 mm., 85 b, 87 
Iron, wire, Cal., 42 a, 44 6 170 
APPENDIX 
66. Labels, paper 
67. Lead, gran., purif., 18 a 
Lead, J g. pieces, Cal., 10 
68. acetate, 195 a 
69. dioxide, purif. 
70. monoxide 
71. nitrate, com'l 
72. oxide, red [Minium], 197 a 
73. Magnesite, gran., 123 a 
74. Magnesium, pulv. 
75. Magnesium, wire, size No. 16, 18 a 
76. chloride, 173 a 
77. sulphate, hydrated, 25 c 
78. Manganese dioxide, pulv., com'l 
79. Manganous chloride (spec.) 
80. Mercuric chloride, 36 a 
Mercurous nitrate, 180 (unless 
made in 179) 
81. Mercury, Cal., 9 a, 179 [with 
dropper) 
Nickel, "reduced," Cal., 43 
82. sulphate, 228 
83. Paraffin, 61 
84. Phosphorus, red 
pentachloride, Cal., 121 e 
pentoxide, Cal., 118 a 
85. Potassium bromate (spec.) 
86. bromide 
87. carbonate, purif. 
88. chlorate, com'l 
89. chloride, 148 a 
90. chromate (spec.) 
91. cyanide, 98% (spec.) 
92. dichromate, pulv., com'l 
93. ferricyanide (spec.) 
94. ferrocyanide (spec.) 
95. -hydrogen sulphate, cryst. 
(spec.) 
96. -hydrogen tartrate, 204 d 
97. hydroxide, purif. 
98. iodide 
99. nitrate, com'l 
100. perchlorate, 48 c 
101. permanganate, com'l 
102. sulphate 
103. Rosin, 28 a, 139 d 
104. Sand, for sand baths 
105. Sawdust, 135 a 
106. Silica, pulv., com'l, 141 
Silver foil, Cal., 11 a 
107. Silver nitrate (spec.) 
108. sulphate (spec.) 
109. Soda-lime, 128 a 
Sodium, Cal., 40 6 
110. Sodium acetate, fused 
111. -ammonium phosphate [Mi- 
crocosmic salt] 
112. carbonate, anhyd. 
113. carbonate, hydrated 
114. chlorate (spec.) 
115. chloride [Common salt] 
116. dichromate, com'l, 213 
117. -hydrogen carbonate 
118. -hydrogen sulphate, 38 
119. -hydrogen sulphite, com'l, 
85 d, 92 d 
120. hydroxide, purif. 
121. nitrate 
122. nitrite, com'l, 103 a 
123. peroxide, 67 a 
124. phosphate 
125. sulphate, anhyd., 33, 176 
126. sulphate, hydrated 
127. sulphide, com'l, 84 a* 
128. sulphite 
129. tetraborate [Borax], pulv. 
130. thiosulphate, com'l, 93 d 
131. Starch, 131, 215 
132. Stannous chloride (spec.) 
133. Strontium chloride, 159 a 
134. sulphate, pulv., 160 d 
135. Sugar, com'l 
136. Sulphur, flowers 
137. roll 
138. Talc [Talcum], pulv., 142 
139. Tin, gran., com'l 
Tin, rod, 60 mm., Cal., 182 
140. Turmeric paper, 144 b 
141. Vaseline 
Wood splinters, 16 cm., Cal. 
142. Wool yarn, white, 110 f, 187 
Yeast, Cal., 133 a 
143. Zinc, gran., com'l 
144. Zinc, pulv. 
Zinc I, 2 g. pieces, Cal., 44 a, 46 
Zinc I, rod 30 to 40 mm., Cal., 170 
145. acetate (spec.) 
146. chloride (spec.) 
147. sulphate (spec.) 
Liquids and Solutions. 
148. Acid, acetic, 6 AT (420 c.c., 80%) 
149. boric (j sat., 35) [for burns 
and cuts] 
150. hydrochloric, cone., 13 N. 
151. hydrochloric, dil., 6 N (467 
c.c.) 
hydrochloric, normal, Cal., N 
152. nitric, cone., 16 N 
153. nitric, dil., 6 N (382 c.c.) 
154. oxalic, 2 N (sat., 126) 
155. picric (20 + 100 c.c. alcohol) 
156. phosphoric, 1.73 sp. gr. 46 N 
pyrogallic, Cal., 101 (278) 
157. sulphuric, cone., 36 N 
158. sulphuric, dil., 6 N (167 c.c.) 
sulphuric, normal, Cal., N 
tartaric, Cal., N (75) 
Alcohol, 95%, Cal. 
159. Alizarin, 20% paste, 189 (50) 
160. Aluminium sulphate, 184, 189, N 
(111) 
161. Ammonium carbonate. 2 N 
(78.5 + 300 c.c. NHiOH) 
162. chloride, 4 N (213.5) 
163. hydroxide, com'l, 7 N * 
164. molybdate + HNOs (70 + 
180 c.c. HNOs) 
165. oxalate, N (71) APPENDIX 
171 
166. sulphide, yellow (NH«HS + S) 
167. thiocyanate, N (76) 
168. Amyl alcohol, 137 b 
169. Barium chloride, N (122) 
170. Barium hydroxide [Baryta water], 
J N (sat., 79) 
171. Benzene, 28 c, d 
172. Bismuth nitrate, 208, N (161 + 
80 c.c. HNOs) 
Bleaching powder, fresh, Cal. (sat.) 
Bromine, element, Cal. 
173. Bromine water, J N (sat.) 
174. Cadmium sulphate, N (140) 
175. Calcium chloride, 2 N (219) 
176. hydroxide [Limewater] 0.04 TV 
(sat.) 
177. Carbon disulphide, com'l 
178. tetrachloride, 28 b, d 
Chlorine-water, Cal. (sat.) 
179. Chloroform 
Chrysophenin, Cal., 187 (10) 
180. Cobalt chloride, N (118.5) 
181. Cochineal solution, 188 
Cottonseed oil, Cal., 140 a, b 
182. Cupric sulphate, N (125) 
Ether, Cal. 
Fehling's sol., Cal., 131, 132 
183. Ferric chloride, N (90) 
Gasoline (petrol), Cal., 28 c, d 
Glucose syrup, com'l, Cal., 133 
184. Glycerine, com'l, 144 c 
185. Hydrogen chloride, sol. in toluene, 
com'l (+CaCl2, for drying) 
Indigo solution, Cal. (1 g. indigo- 
carmine), 96 a 
Kerosene, Cal., 140 a 
186. Lead nitrate, N (165) 
187. Litmus solution, neutral 
188. Magnesium sulphate, N (123) 
Malachite green, Cal., 190 (0.5) 
189. Manganous chloride, 219, N (99) 
190. Mercuric chloride, J N (sat., 68) 
191. Mercurous nitrate, i N (70 + 4 
c.c. HNOs + Hg) 
Methyl acetate, Cal., 137 c 
192. orange, 155 a (1) 
violet, Cal., 190 (0.5) 
193. Nickel sulphate, 228, N (131.5) 
Petrol, see gasoline 
194. Phenolphthalein (1 + 500 c.c. al- 
cohol) 
Phosphorus trichloride, Cal., 221 b 
195. Potassium arsenate [KH2ASO4], 
2 N (120) 
196. arsenite [KAsO2 + HsAsOs 
(90)] 
197. bromate, 99 c, J N (59) 
198. bromide, N (119) 
199. chlorate, saturated, J N (sat., 
161) 
200. chloride, saturated, 4 N (sat., 
320) 
201. chromate, 212, N (97) 
202. cyanide, N (65)* 
203. dichromate, com'l, N j (74) 
204. ferricyanide, 222 e, % N (55) 
205. ferrocyanide, J N (53) 
hydroxide, Cal., 101 (840) 
206. iodide, i N (83) 
207. permanganate, J N (79) 
208. Silver nitrate, J N (42.5) 
209. sulphate, N (sat., 5.5) 
Soap, Cal., 140 (91) 
210. Sodium acetate, 83 a, 158 c, N 
(136) 
211. carbonate, 2 N (106 NazCOa)* 
chlorate, sat., Cal., 155 b, 6J 
N (sat., 692) 
chloride, sat., Cal., 155 b, 5J 
N (sat., 322) 
212. -hydrogen sulphate, satu- 
rated, com'l 
213. hydroxide, 2 N (80) * 
214. phosphate, N (119) 
sulphate, Cal., 187 (8) 
215. thiosulphate, N (124) 
216. Stannous chloride, 181 g, N (112.5 
+ 500 c.c. HC1 + Sn) 
217. Starch emulsion 
218. Strontium chloride, 159, N (133) 
Tannic acid, Cal., 190 (10) 
Tartar Emetic, Cal., 190 (10) 
219. Toluene, com'l, 68 g 
220. Zinc acetate, | N (59) 
221. chloride, 175, i N (34 ZnCh) 
222. sulphate, J N (72). REFERENCES 
TO THE 
GENERAL CHEMISTRY FOR COLLEGES 
The references given in this Laboratory Outline are to the Introduction to General 
Inorganic Chemistry (3d ed., 1917). These references are arranged below in numerical 
order, and opposite to them are placed the corresponding pages in the General Chem- 
istry for Colleges (2nd ed., 1916). 
Inorg. 
Coll. 
Inorg. 
Coll. 
Inorg. 
Coll. 
Inorg. 
Coll. 
29 
168 
278 
201 
486 
318 
656 
461 
40 
19 
279 
200 
514 
338 
672 
451 
41 
20 
279 
202 
515 
340 
691 
465 
42 
13 
281 
205 
526 
348 
695 
468 
54 
17 
282 
206 
528 
350 
697 
471 
63 
65 
283 
206 
530 
351 
711 
479 
71 
45 
305 
189 
537 
356 
713 
481 
85 
28 
319 
224 
543 
360 
716 
484 
94 
321 
223 
550 
364 
722 
489 
97 
29 
324 
210 
553 
366 
726 
494 
110 
72 
333 
216 
553 
367 
740 
504 
116 
51 
336 
214 
556 
368 
743 
506 
117 
52 
337 
216 
557 
368 
744 
507 
117 
53 
356 
236 
560 
372 
744 
508 
120 
55 
358 
238 
561 
373 
745 
509 
123 
475 
361 
239 
569 
378 
745 
586 
126 
58 
377 
247 
573 
381 
746 
510 
129 
59 
378 
248 
576 
384 
767 
526 
129 
60 
379 
250 
594 
399 
771 
529 
130 
60 
382 
252 
597 
398 
774 
531 
145 
87 
383 
253 
605 
404 
778 
534 
150 
94 
387 
254 
606 
405 
779 
534 
151 
96 
392 
258 
609 
407 
780 
535 
154 
97 
394 
255 
610 
408 
781 
536 
182 
124 
396 
611 
409 
782 
536 
183 
125 
397 
613 
411 
783 
537 
188 
128 
399 
271 
616 
413 
801 
551 
193 
132 
400 
245 
617 
413 
812 
557 
193 
133 
402 
258 
618 
414 
820 
564 
197 
135 
403 
259 
619 
415 
821 
565 
198 
135 
404 
260 
620 
415 
828 
572 
199 
134 
417 
269 
622 
416 
832 
576 
207 
142 
418 
272 
623 
417 
842 
584 
208 
143 
421 
272 
626 
421 
846 
588 
211 
145 
437 
285 
627 
422 
849 
592 
220 
438 
286 
630 
425 
861 
602 
221 
160 
441 
288 
632 
427 
862 
603 
245 
108 
474 
308 
634 
428 
882 
623 
271 
196 
476 
310 
639 
432 
894 
509 
273 
476 
311 
645 
436 
895 
634 
275 
199 
448 
647 
437 
896 
635 
276 
200 
481 
559 
648 
437 
897 
636 
277 
277 
483 
314 
654 
440 
900 
639