EXAMINATION OF WATER. 
LEFFMANN. BY THE SAME AUTHOR. 
ANALYSIS 
OF 
MILK AND MILK PRODUCTS. 
i2mo. g2 pages. Illustrated. $1.25. 
A COMPEND OF CHEMISTRY, 
INCLUDING URINARY ANALYSIS. 
ESPECIALLY ADAPTED TO STUDENTS IN MEDICINE 
AND DENTISTRY. 
Fourth Edition. Revised. 
Price .80. Interleaved for taking Notes, $1.25. 
SANITARY RELATIONS 
OF THE 
COAL-TAR COLORS. 
BY THEODORE WEYL. 
AUTHORIZED TRANSLATION. 
i2tno. 154 pages. $1.25. 
P. BLAKISTON, SON & CO., Philadelphia. Examination of Water 
FOR 
SANITARY AND TECHNIC PURPOSES. 
BY 
HENRY LEFFMANN, A.M., M.D., Ph.D., 
PROFESSOR OF CHEMISTRY IN THE WOMAN'S MEDICAL COLLEGE OF PENNSYLVANIA, 
IN THE PENNSYLVANIA COLLEGE OF DENTAL SURGERY, AND IN THE WAGNER 
FREE INSTITUTE OF SCIENCE; PATHOLOGICAL CHEMIST TO THE 
JEFFERSON MEDICAL COLLEGE HOSPITAL; CHEMIST TO 
DAIRY AND FOOD COMMISSIONER OF PA. 
THIRD EDITION, REVISED AND ENLARGED, WITH 
ILLUSTRA TIONS. 
PHILADELPHIA: 
P. BLAKISTON, SON & CO., 
IOI2 WALNUT STREET. 
1895. Copyright, 1895, by P. Blakiston, Son & Co. 
PRESS OF WM F. FELL 4 CO , 
1220*24 8ANS0M 8TREET, 
PHILADELPHIA. I DEDICATE THIS BOOK TO THE 
MEMORY OF 
MY MOTHER, 
TO WHOSE WISE PRECEPT AND EXAMPLE 
IN MY BABYHOOD 
I OWE WHATEVER MERIT MY MANHOOD YEARS 
MAY SHOW. PREFACE TO THIRD EDITION. 
In the present edition the general character of the work 
as heretofore exhibited has been preserved, but numerous 
modifications of the details of processes of sanitary analy- 
sis as developed by various American workers have been 
described. Much valuable matter has of late years been 
contributed by the various State stations for sanitary con- 
trol, and while these methods have not solved the difficult 
problem presented to the sanitary chemist, namely, the 
absolute judgment as to whether a given water-sample is or 
is not wholesome, they have aided in securing uniformity of 
results, and the accumulation of data upon which judgment 
may be formed. Much of the text in the section on bio- 
logic examinations has been re-written, and I have taken 
occasion to express more at length the sources of un- 
certainty in this field; sources which were recognized 
and pointed out in both the earlier editions, but which 
have become much more appreciable to the profession at 
large within the last few years. Whatever may be the 
shortcomings of the standard analytic examinations, it 
seems probable that for some years to come, at least, 
the results will remain the most satisfactory basis for 
judgment as to the potability of a water. There can be no 
question that many of the published results as to bacterio- 
logic examinations of water-samples are without value, 
VII VIII 
PREFACE TO THIRD EDITION. 
partly from the inherent difficulties of the methods, even 
in the most expert and honest hands ; partly, it is to be 
regretted, from absolute misstatement. I have had per- 
sonal knowledge of one instance of the latter phase. 
My former colleague, Dr. William Beam, now perma- 
nently residing in a distant part of the world, has asked 
to be relieved from his share in the work. The copy- 
right privileges have been formally transferred to me, 
and I have conducted entirely the work of the present 
revision. H. L. 
7/5 Walnut St. 
Philadelphia, August 1895. PREFACE TO SECOND EDITION. 
In the period that has elapsed since the publication of 
the first edition of this work, many processes for water 
analysis have been proposed, and we have included in the 
present revision such of these as seem to us of substantial 
value. In particular we may mention the methods recom- 
mended by the Chemical Section of the American Associa- 
tion for the Advancement of Science, and the application 
of the Kjeldahl process to the determination of the organic 
nitrogen. The adoption of the former methods will serve 
to secure uniformity in analytical data, while it is to be 
hoped that chemists generally will investigate and report 
on the latter, in order that a basis for the interpretation of 
results may be obtained. 
No material change has been made in the description of 
the general Quantitative Analysis, in which we have fol- 
lowed to a large extent the methods indicated by Fresenius, 
selecting those best adapted to technical purposes. 
We have extended considerably the section on the 
Biological Examinations, although we have seen no reason 
to change the opinions expressed in the former edition as 
to the value of these results. It would be impossible to 
overestimate the importance of bacteriology, in etiology, 
pathology, and general biology, but until pathogenic mi- 
crobes are more clearly indicated and described, the PREFACE TO SECOND EDITION. 
X 
methods will be of little use in dealing with the problem 
of the determination of the sanitary and technical value 
of water supplies. 
In the chapter on the Purification of Water we have 
described in some detail a few of the important systems, 
especially the Anderson iron process, the efficiency of 
which we have had ample opportunity to observe by ex- 
periments on a comparatively large scale, extending over 
several months. 
The favorable reception accorded to the first edition, 
both by journals of acknowledged authority, and by 
chemists of extended experience in this department, has 
indicated that the work is not without usefulness in the 
field to which it is devoted. H. L. 
W. B. CONTENTS. 
History and Classification of Natural Waters. 
Rain Water—Surface Water—Subsoil Water—Deep 
Water, 13-20 
PAGES 
Analytic Operations. 
Sanitary Examinations:— 
Collection and Preliminary Examination—Total 
Solids—Chlorin—Nitrogen in Ammonium Com- 
pounds and Organic Matter—Nitrogen as Nitrates 
—Nitrogen as Nitrites—Oxygen-consuming Power 
— Phosphates — Dissolved Oxygen — Poisonous 
Metals—Biologic Examinations, . 21-74 
Technic Examinations:— 
General Quantitative Analysis—Spectroscopic Anal- 
ysis—Specific Gravity, 74-88 
Interpretation of Results. 
Statement of Analysis—Sanitary Applications—Ac- 
tion of Water on Lead, 89-109 
Technic Applications. 
Boiler Waters—Sewage Effluents—Purification of 
Water—Identification of Source of Water, . . . 109-135 
Addenda, 136-140 
Analytic Data. 
Factors for Calculation—Conversion Table—Oxygen 
Dissolved in Water—Rain and Subsoil Waters— 
Schuylkill Water—Artesian Waters—City Supplies 
—Culture Phenomena 141-149 
Index, 151—154 
XI CORRECTIONS. 
On page 137, lines 6 and 5 from bottom should read “nutrient agar- 
agar of definite reaction (see below for methods of determining re- 
action), to which 2 to 3 per” 
On same page, line 2 from bottom, for typhus read typhi. EXAMINATION OF WATER. 
HISTORY AND CLASSIFICATION OF NATURAL 
WATERS. 
Pure water is an artificial product. Natural waters 
always contain foreign matters in solution and suspension, 
varying from mere traces to very large proportions. The 
properties, effects, and uses of water are considerably modi- 
fied by these ingredients, and the object of analysis is to 
ascertain their character and amount. Since these are 
largely dependent on the history of the water, a classifica- 
tion based on this will be convenient. We may distinguish 
four classes of natural waters : — 
Rain Water.—Water precipitated from the atmosphere 
under any conditions, and therefore including dew, frost, 
snow, and hail. 
Surface Water.—All collections of water in free contact 
with the atmosphere, as in streams, seas, lakes, or ponds. 
Subsoil or Ground Water.—Water not in free contact 
with the atmosphere, percolating or flowing through soil 
or rock at moderate distance below the surface, and 
derived in large part from the rain or surface water of 
the district. 
Deep or Artesian Water.—Water accumulated at con- 
siderable depth below the surface, from which the subsoi 
13 14 
HISTORY‘AND CLASSIFICATION. 
water of the district has been excluded by difficultly per- 
meable strata. 
Rain Water, when gathered in the open country and 
in the later period of a long rain or snow, is the purest 
form of natural water. When collected directly, it con- 
tains but little solid matter, this consisting principally of 
ammonium compounds and particles of organic matter, 
living and dead, gathered from the atmosphere. In dis- 
tricts near the sea an appreciable amount of chlorids will 
be present. It is obvious that a prolonged rain will wash 
out the air, but since storms are usually attended by wind, 
fresh portions of air are continually flowing in, and thus 
the water never becomes perfectly pure. Rain water col- 
lected in inhabited districts is usually quite impure. 
Surface Water.—Rain water in part flows off on the 
surface, and gains in the proportion of suspended and dis- 
solved matters, the former being found in large amount 
when the rainfall is profuse. The wearing action of water 
is dependent on the amount and character of these sus- 
pended materials. From the higher levels of a watershed, 
the streams, more or less in the form of torrents, gather 
into larger currents, and reaching lower levels become 
slower in movement, and deposit much of the suspended 
matter. By admixture of the waters from widely separated 
districts the character and amount of the dissolved matters 
are much modified. An action of this kind is seen in the 
watershed of the Schuylkill River. This stream rises in the 
anthracite-coal region of Pennsylvania, and receiving much 
refuse mine-water becomes impregnated with iron salts and 
free mineral acid, being then quite unsuitable for drinking 
or manufacturing purposes. In its course of about one 
hundred miles it passes over an extensive limestone dis- SUBSOIL WATER. 
trict, and receives several large streams highly charged with 
calcium carbonate. The result is a neutralization of the 
acid and a precipitation of the iron and much of the 
calcium. The river becomes purer, and at its junction 
with the Delaware River at Philadelphia it contains neither 
free sulphuric nor hydrochloric acid, only traces of iron, 
and but a small amount of calcium sulphate. In this man- 
ner there is produced a soft water, superior to that of the 
river near its source, or to the hard waters of the middle 
Schuylkill region. 
It is obviously impossible to establish close standards of 
composition for surface waters. In the case of rain water, 
falling on the surface of undisturbed, unpopulated terri- 
tory, the amount of solids dissolved will be small, and 
will consist principally of carbonates and sulphates. The 
water of lakes and rivers is, however, in part derived from 
springs, which may proceed from great depths, and thus 
introduce substances not easily soluble in surface water, 
nor derivable from the soil of the district. 
The exposure to light and air which surface water under- 
goes, results in the absorption of oxygen and loss of car- 
bonic acid, together with the oxidation of the organic 
matter. The diminution of the rapidity of the current 
permits the deposition of the suspended matters, and this 
occurs especially as the river approaches the sea, not only 
from the retarding influence of the tidal wave, but from 
the precipitating action of the salt water. The investiga- 
tions of Carl Barus, published in Bulletin No. 36, U. S. 
Geological Survey, have shown the decided influence of 
sodium chlorid in accelerating the subsidence of fine 
particles. 
Subsoil Water.—Water that penetrates the soil, 16 
HISTORY AND CLASSIFICATION. 
passes to various depths, according to the porosity and 
arrangement of the strata. As a rule, it descends until it 
reaches but slightly pervious formations, upon the level of 
which it accumulates. In the upper layer of soil it 
dissolves mineral and organic ingredients, and becomes 
impregnated with microdrganisms, through the agency of 
which the organic matter undergoes important transforma- 
tions. The water constantly accumulating, gradually flows 
along the incline of the impervious stratum, or through its 
fissures, and may either pass downward or emerge in the 
form of a spring. 
The proportion of water which may be held by any 
rock or soil is often much larger than would be at first 
supposed. T. Sterry Hunt states that a square mile of 
sandstone ioo feet thick will contain water sufficient to 
sustain a flow of a cubic foot a minute for more than thir- 
teen years. 
Much difference is observed in the composition of sub- 
soil waters, but as a general rule they contain but a limited 
amount of mineral substances, and a very small propor- 
tion of organic matter. In populated districts, however, 
a marked change is produced through admixture with 
water containing animal and vegetable products in various 
stages of decomposition. It is especially the organic mat- 
ter containing nitrogen that is of importance. To this 
class belong all those compounds forming tissues that are 
intimately associated with vital action ; also many charac- 
teristic excretory products. These bodies are mostly 
unstable, and as soon as their vitality ceases begin to 
decompose, partly by oxidation, partly by splitting up 
into simpler forms; these changes being in most cases 
brought about by microorganisms. Among the products SUBSOIL WATER. 
noticed in the early stages of such decay, are substances 
which possess close analogies to the organic bases or alka- 
loids, but more susceptible of decomposition. They are 
generally present in minute amount, but are not infre- 
quently very active in their physiological effect. From 
the most recent researches it seems probable that the 
pathogenic power of many microorganisms rests not upon 
any mechanical or other action of the germs themselves, 
but upon the alkaloidal principles which they produce and 
excrete. As a group these bodies are known as the 
“ptomains.” Nitrogen is an invariable ingredient. The 
ultimate results of the processes of decomposition depend 
largely on circumstances. When organic matters contain- 
ing nitrogen are subjected to the action of oxidizing 
agents, such as alkaline potassium permanganate or 
chromic acid, some of the nitrogen is converted into 
ammonium compounds. A similar result occurs in all 
waters, but a considerable portion of the organic matter 
may also suffer further oxidation, and in association with 
the mineral substances present form nitrites and nitrates, 
especially the latter. This conversion is called “nitrifi- 
cation.” The conditions under which it occurs have 
been carefully studied by various observers, but much 
research is still needed to place the subject on a secure 
basis. 
Nitrification takes place under the influence of microbes, 
the habitat of which does not extend more than a few 
yards below the surface of the soil. Percy and Grace 
Frankland have isolated and described a bacillus with active 
nitrifying powers. It is a very short, almost spherical 
form, which grows in ammoniacal culture-fluids and in 
meat-broth, but does not grow in the usual gelatin-peptone 
B HISTORY AND CLASSIFICATION. 
mixture, except when previously cultivated in meat-broth. 
The nitrifying action is probably exerted only upon the 
ammonium which is formed from the organic matter. The 
presence of some substance capable of neutralizing acids is 
necessary to continuous action. Calcium and magnesium 
carbonates fulfill this function. Nitrates are the final result 
of this action ; nitrites are present at any given time only 
in small quantity. Denitrification, that is, the reduction 
of nitrates and nitrites to ammonium compounds, takes 
place also under the influence of microbes, and is especially 
apt to occur when considerable quantities of decomposing 
organic matter are introduced. Percy and Grace Frank- 
land have described several species of bacilli which have 
active denitrifying powers. Among these are Bacillus 
liquidus, B. vet7nicularis, and B. ramosus. A partial 
reduction sometimes occurs, and a notable proportion 
of nitrites is found, but in the presence of actively de- 
composing organic matter, such as that in sewage, a 
complete reduction, even to the liberation of nitrogen, 
may occur. Jordan (.Rep. S. B. of II., of Mass., 1890), 
has described several species, found in the sewage of the 
city of Lawrence, which reduce nitrates rapidly to nitrites. 
Deep Water.—Water which penetrates the fissures of 
the fundamental rock formations may pass to great depths, 
and by following the lines of the lowest and least permeable 
strata may be transported to points far removed from those 
at which it was originally collected. The chemical changes 
thus induced include most of those which take place at 
higher points, but the increase of pressure and temperature 
confers increased solvent power. Carbonic acid will 
accumulate under conditions favorable to the solution of 
calcium, magnesium, and iron carbonates, and iron and DEEP WATER. 
manganese oxids may be converted into carbonates and 
then dissolved. Sulphates are reduced to sulphids, and 
these subsequently, by the action of carbonic acid, yield 
hydrogen sulphid. Organic matter, living and dead, plays 
an important part, determining the reduction of ferric 
compounds to ferrous, and of the sulphates to sulphids, and 
is itself converted ultimately into ammonium compounds, 
notable quantities of which are often found in-deep waters. 
Further, it is found that nitrates and nitrites are present 
only in small amount, except from certain strata rich in 
organic matter. In some cases the water acquires very 
high temperature, and dissociation of rocks occurs with 
solution of considerable amounts of silicic acid, which is 
ordinarily but sparingly soluble in water. 
Masses of water thus accumulated under heat and pres- 
sure may find their way to the surface either through 
natural fissures, or be reached by borings. The mineral 
springs, highly charged with solid matters, and the artesian 
waters are obtained in this way. 
While no absolute unchangeable line can be drawn be- 
tween deep and subsoil waters, yet it will in most cases be 
found that the deep water of a given district, whether 
obtained through natural or artificial channels, will be 
decidedly different in composition from the subsoil or sur- 
face water of the same, and that the rocks passed through 
in such cases will be characterized by one or more strata, 
difficultly permeable to water, and therefore preventing 
direct communication. The characteristic differences be- 
tween surface, subsoil, and deep waters are clearly indi- 
cated in the table of analyses given in the appendix. 
The fact that mere depth is not the essential difference 
between the two classes of waters is shown by comparison 20 
HISTORY AND CLASSIFICATION. 
between the composition of the water from the well at 
Barren Hill, on the northern border of Philadelphia 
county, and the deep well at Locust Point, Baltimore. 
The former is a dug well, 130 feet deep; the latter is an 
artesian boring of 128 feet, which in its descent passes 
through four feet of solid rock. The deeper well is evi- 
dently supplied by subsoil water. The artesian well, 
though located 100 yards from a brackish sewage-laden 
estuary, evidently derives no water from it. ANALYTIC OPERATIONS. 
SANITARY EXAMINATIONS. 
COLLECTION AND PRELIMINARY EXAMINATION 
OF SAMPLES. 
Great care must be taken in collecting water-samples 
in order to secure a fair representation of the suppl) 
and to avoid introduction 
of foreign matters. The 
five-pint green glass stop- 
pered bottles used for 
holding acids are suitable 
for containing the sam- 
ples. The contents of 
one such bottle will suf- 
fice for most sanitary or 
technical examinations. 
Fig. i shows a boxed bot- 
tle known as “ Banker’s 
Glass Can,” which I have 
found very convenient 
for transportation. It is 
provided with a hinged 
lid which can be fastened, if deemed necessary, by a 
padlock. The green-glass stoppered bottles may be fitted 
in such an arrangement. Stone jugs, casks, or metal 
vessels must not be employed. The bottles used must be 
Fig. i. 22 
ANALYTIC OPERATIONS. 
thoroughly rinsed several times with the water to be ex- 
amined, filled and the stopper tied down, or fastened by 
stretching a rubber finger-cot over the stopper and lip. If 
corks are used, they should be new and thoroughly rinsed. 
Wax, putty, plaster, or similar material should not be 
used. 
In taking samples from lakes, slow streams, or reservoirs, 
it is necessary to submerge the bottle so as to avoid col- 
lecting any water that has been in immediate contact with 
the air. 
In the examination of public water supplies, the sample 
should be drawn from a hydrant in direct connection with 
the main, and not from a cistern, storage tank, or dead 
end of a pipe. In the case of pump-wells, a few gallons 
of water should be pumped out before taking the sample, 
in order to remove that which has been standing in the 
pipe. 
In all cases care should be taken to fill the vessel with 
as little agitation with air as possible. 
It is important that with each sample a record be made 
of those surroundings and conditions which might influ- 
ence the character of the water, particularly in reference 
to sources of pollution, such as proximity to cesspools, 
sewers, or manufacturing establishments. The character 
and condition of the different strata of the locality should 
be noted if possible. 
Determinations of nitrogen existing as ammonium com- 
pounds, and as organic matter, and of oxygen-consuming 
power, should be made upon the sample in the original 
condition, whether turbid or clear, but all other estima- 
tions should be made upon the clear liquid. Turbid waters 
may be clarified by standing or by filtration ; for the latter SANITARY EXAMINATIONS. 
23 
purpose Schleicher & Schull’s extra-heavy No. 598 paper 
is the best. In many cases the suspended matter cannot 
be entirely removed by filtration, and subsidence must be 
resorted to. The use of a small quantity of alum, or 
aluminum hydroxid, as described in the section on the 
purification of water, will sometimes be applicable as a 
means of clarifying samples. For the quantitative deter- 
mination, the sediment from a known volume of the water 
is collected on a tared filter, dried at 1120 F., and weighed. 
The water from newly-dug wells is generally turbid and 
the determinations are best made after filtration, but the 
results will be unsatisfactory, showing a higher proportion 
of organic matter than will be found when the supply be- 
comes clear. 
The following methods of determining color and odor 
have been adopted by the Society of Public Analysts of 
Great Britain : — 
Color.—A colorless glass tube, two feet long and two 
inches in diameter, is closed at each end with a disc of 
colorless glass. An opening for filling and emptying the 
tube should be made at one end, either by cutting a small 
segment off the glass disc, or cutting out a small segmental 
section of the tube itself before the disc is cemented on. 
A good cement for such purposes is the following : — 
Caoutchouc, 2 parts. 
Mastic 6 “ 
Chloroform, IOO “ 
The ingredients are mixed and allowed to stand for a 
few days. The cement should be used as soon as solution 
is effected, as it becomes viscid on standing. 
The tube must be about half filled with the water to be 
examined, brought into a horizontal position, level with 24 
ANALYTIC OPERATIONS. 
the eye, and directed toward a brightly illuminated white 
surface. The comparison of tint has to be made between 
the lower half of the tube containing the water under ex- 
amination, and the upper half containing air only. 
By determining the amount of ammonium chlorid re- 
quired to produce with a standard quantity of Nessler solu- 
tion a color equal in depth to that of the water-sample, a 
means of recording the color with some precision may 
often be obtaiifed. The manipulation is conducted as de- 
scribed in connection with the determination of ammonium 
compounds, using equal volumes of the sample and of dis- 
tilled water in separate cylinders. The Nessler solution 
is, of course, added only to the distilled water. The 
volume of diluted standard ammonium chlorid solution 
which must be added to the distilled water to enable it 
to produce with the Nessler reagent a color equal to that 
of the sample is taken as an index of the color of the 
latter. Thus “ color = 0.3 ” means that the color of the 
sample equals that produced by Nessler solution in distilled 
water to which o. 3. c. c. of the diluted standard ammonium 
chlorid solution has been added. 
Odor.—Put about 150 c. c. of the water into a clean, 
wide-mouth 250 c. c. stoppered bottle, which has been 
previously rinsed with the same water ; insert the stopper 
and warm the water in a water-bath to ioo° F. Remove 
the bottle from the water-bath and shake it rapidly for a 
few seconds ; remove the stopper and immediately note if 
the water has any smell. Insert the stopper and repeat the 
test. 
In a polluted water the odor will sometimes give a clue 
to the origin of the pollution. 
Reaction.—The determination of reaction is usually SANITARY EXAMINATIONS. 
25 
made by the addition of a neutral solution of litmus to the 
water. If an acid reaction is obtained the water should 
be boiled in order to determine if it is due to carbonic 
acid. Some of the more delicate indicators, such as 
phenolphthale'in and lacmoid, may be used with advantage 
for these tests. The latter possesses the advantage that it 
is unaffected by carbonic acid, but detects even traces of 
free mineral acid. It is neutral, also, to many normal 
metallic salts, such as ferrous sulphate, which are acid to 
litmus. Ferric salts, however, are acid to lacmoid. Its 
color changes are the same as those of litmus, i. e., red 
with acids and blue with alkalies. 
Phenolphthale'in is best applied to the detection of weak 
acids, such as carbonic acid and the organic acids. In 
acid and neutral solutions it is colorless—in alkaline, deep 
red. Nearly all waters contain carbonic acid, and will 
therefore bleach a solution of phenolphthale'in which has 
been reddened by a small amount of alkali. 
TOTAL SOLIDS. 
A platinum basin holding ioo c. c. will be found con- 
venient for this determination. This should weigh about 
45 grams. It should be kept clean and smooth by frequent 
burnishing with sand, a little of which should be placed in 
the palm of the hand, moistened, and the dish gently 
rubbed against it. Very fine sea-sand with round, smooth 
grains, is the only kind suitable for this purpose. Coarse 
river-sand, tripoli, or other rough scouring-powders, must 
not be employed. If proper care is taken, the lustre of 
the metal will remain unimpaired indefinitely, and the loss 
in weight will be trifling. The inner surface can generally 
be cleaned by treatment with hydrochloric acid, rinsing 26 
ANALYTIC OPERATIONS. 
and, if necessary, burnishing. Neglect of these pre- 
cautions will soon lead to serious damage to the dish. A 
small, smooth slab of iron or marble is convenient to set 
it on while cooling. When being heated over the naked 
flame the dish should rest on a triangle of iron wire, 
covered with pipe-stems. Dishes of pure nickel are not 
satisfactory substitutes for those of platinum. 
Platinum-pointed forceps should be used in handling 
the dish. The platinum terminals may be kept bright and 
clean by the use of sand. 
The low-temperature burner, 
used as shown in Fig. 2, will be 
found a very convenient substi- 
tute for the water-bath and hot 
air oven. The inlet pipe is very 
short and soon becomes so hot 
as to injure the rubber tube. To 
avoid this it may be lengthened 
by means of a piece of 
gas-pipe, or the junction may be 
wrapped with a rag, the ends of which dip into water. 
By capillary attraction the rag is kept moist and cool. 
Fig. 2. 
The determination of total solids is made by evaporating 
ioo or 200 c. c. of the water in the platinum basin, which 
has been previously heated almost to redness, allowed to 
cool for ten minutes, and weighed. The operation is 
conducted at a moderate heat. When the residue appears 
dry, the heat may be increased slightly for some minutes. 
The above method will answer in most cases. In waters 
of exceptional purity it may be advisable to use larger 
quantities, such as 250 c. c. When the residue contains 
deliquescent bodies, the determination will not be accurate, SANITARY EXAMINATIONS. 
27 
and when appreciable amounts of magnesium and chlorin 
are present, a decomposition will occur toward the close 
of the evaporation by which magnesium oxid will be 
formed and hydrogen chlorid escape. 
The irregular decomposition occurring during the evap- 
oration may be largely prevented by adding .005 gm. of 
sodium carbonate to each 100 c. c. of the sample taken. 
This converts magnesium and calcium salts into carbonates. 
The sodium carbonate is conveniently kept in the form of 
solution of such strength that 1 c. c. contains .001 gm. 
The weight of the carbonate is of course to be deducted 
from the weight of the residue. Drown and Hazen have 
carefully investigated this method and have found it avail- 
able for a more satisfactory determination of the loss on 
ignition. For this process they place the platinum basin 
containing the residue within another similar basin of such 
size that an air-space of about one-half inch is left all 
around the inner dish, which is supported upon a spiral of 
platinum that rests on the bottom of the outer dish. Over 
the inner dish is suspended a disc of platinum foil to 
reflect the heat. The outer dish is heated to bright red- 
ness. 
After the weight of the residue is obtained, the dish 
should be cautiously heated to low redness, and the effect 
noted. Nitrates and nitrites, calcium and magnesium 
carbonates are decomposed ; ammonium salts are driven 
off; potassium and sodium chlorids are also driven off if 
the temperature is high. Organic matter is at first 
charred, and by continued heating burned off. When the 
quantity of nitrates is considerable, slight deflagration may 
be observed, or the production of red fumes of nitrogen 
dioxid. The organic matter, in decomposing, not infre- 28 
ANALYTIC OPERATIONS. 
quently develops odors which indicate its character or 
source. These are more satisfactorily observed when a 
rather large quantity, say 250 c. c., is evaporated at a low 
heat, preferably on a water-bath. 
In water of high organic purity, the residue on heating 
will give no appreciable blackening nor odor, while in 
forest streams charged with vegetable matter derived from 
falling leaves, very decided blackening without unpleasant 
odor will be noticed. The loss of weight after heating 
cannot be taken as a measure of the organic matter, except 
when present in relatively large amount. 
Solutions Required :— 
CHLORIN. 
Standard Silver Nitrate.—Dissolve about five grams of 
pure recrystallized silver nitrate in distilled water, and 
make the solution up to 1000 c. c. The amount of chlorin 
to which this is equivalent may be determined as follows: 
Several grams of pure sodium chlorid are finely powdered 
and heated over a Bunsen burner for five minutes, not quite 
to redness. When cold, 0.824 gram is dissolved in water 
and the solution made up to 500 c. c. 25 c. c. of this 
should be treated as below, and the amount of silver solu- 
tion required noted. Each c. c. of the sodium chlorid 
solution is equivalent to .001 gram chlorin. 
Potassium Chromate. —Five grams of potassium chro- 
mate are dissolved in too c. c. of distilled water. A solu- 
tion of silver nitrate is added until a permanent red 
precipitate is produced, which is separated by filtration. 
Analytic Process : — 
If a preliminary test shows the chlorin to be present in 
considerable amount, the determination may be made on SANITARY EXAMINATIONS. 
29 
xoo c. c. of the water without concentration. If, how- 
ever, there is but little present, 250 c. c. should be evap- 
orated to about one-fifth, best with the addition of a little 
sodium carbonate, and the determination made on the 
concentrated liquid after cooling. 
The water is placed in a porcelain dish or in a beaker 
standing on a white surface, a few drops of potassium 
chromate solution added, and standard silver nitrate solu- 
tion run in from a burette until a faint red color of silver 
chromate remains permanent on stirring. The proportion 
of chlorin is then calculated from the number of c. c. 
of silver solution added. For greater accuracy a second 
determination may be made, using as a comparison the 
liquid first titrated, the red color having been previously 
discharged by a few drops of sodium chlorid solution. 
The water should always be as nearly neutral as possible 
before titration. If acid, it may be neutralized by the 
addition of sodium carbonate. 
The residue obtained by evaporating the water with 
sodium carbonate as described in connection with the de- 
termination of the total solids will serve conveniently for 
estimating the chlorin. It is best to use 200 c. c. of the 
sample and redissolve the residue in about 50 c. c. of 
distilled water, rubbing the sides of the dish well with a 
rubber-tipped rod, and then titrating as indicated above. 
NITROGEN IN AMMONIUM COMPOUNDS AND IN OR- 
GANIC MATTER. 
The nitrogen in ammonium compounds, and a part of 
that in the organic matter, is determined by a process of 
distillation first developed fully by Messrs. Wanklyn, 
Chapman, and Smith. It depends upon the conversion of ANALYTIC OPERATIONS. 
the nitrogen into ammonium compounds and subsequent 
estimation in the distillate. 
Apparatus Required: — 
Distilling Apparatus.—That shown in Fig. 3 has been 
found to be the most convenient. The still consists of a 
Fig. 3. 
Bohemian glass retort of about 1000 c. c. capacity. The 
beak of the retort should incline slightly upward, to 
prevent contamination by splashing. At about two inches 
from the end it should be bent at a right angle, and drawn 
out so as to enter the condensing worm for about an inch, SANITARY EXAMINATIONS. 
31 
and terminate beneath the level of the water. Glass 
worms are apt to crack, and it is more satisfactory to use 
Fig. 4. 
Scale IK in.= 1 foot. 
one of block tin. A piece of rubber tubing is drawn over 
the junction. A rapid current of cold water should be main- 
tained through the condenser. The heat is applied by ANALYTIC OPERATIONS. 
means of the low-temperature burner, the iron ring of 
which is removed so that the retort rests directly on the 
gauze. With this arrangement the heat is under perfect 
control, and the danger of fracturing the glass is reduced 
to a minimum. It is advisable to protect the retort from 
drafts of cold air. 
Another convenient form of apparatus is shown in Fig. 
4. It is employed in the laboratory of the Massachusetts 
State Board of Health. (A. H. Gill, The Analyst, xvm.) 
Cylinders for Comparison-Color Tests, about 2.5 cm. in 
diameter and holding 100 c. c., made of colorless glass. 
Solutions Required :— 
Sodium Carbonate.—50 grams of pure sodium carbonate 
are strongly heated, dissolved in 250 c. c. of distilled 
water, and the solution boiled down to 200 c. c. 
Ammonium-Free Water.—If the distilled water of the 
laboratory gives a reaction with Nessler reagent, it should 
be treated with sodium carbonate, about one grain to the 
liter, and boiled until about one-fourth has been evapor- 
ated. Ammonium-free water may be obtained by distill- 
ing, in a retort, water made slightly acid with sulphuric 
acid. 
StandardAmmonium Chlorid.—Dissolve 0.382 gram of 
pure dry ammonium chlorid in 100 c. c. of ammonium- 
free water. For use, dilute 1 c. c. of this solution with 
pure water to 100 c. c. 1 c. c. of this dilute solution con- 
tains .00001 gram of nitrogen. 
Nessler Reagent.—Dissolve 35 grams of potassium iodid 
in 100 c. c. of water. Dissolve 17 parts of mercuric chlorid 
in 300 c. c. of water. The liquids may be heated to aid 
solution, but must be cooled before use. Add the mercuric 
chlorid solution to that of the potassium iodid, until a per- SANITARY EXAMINATIONS. 
33 
manent precipitate is produced. Then dilute with a 20 
per cent, solution of sodium hydroxid to 1000 c. c., add 
mercuric chlorid solution until a permanent precipitate 
again forms and allow to stand until clear. Nessler and 
other reagents are best kept in glass-capped bottles, Fig. 
5, in which the pipette may remain when not in use. The 
solution improves by keeping. 
Alkaline Potassium Permanganate.—Dissolve 
200 grams of potassium hydroxid, in sticks, and 
eight grams of potassium permanganate, in a liter 
of distilled water. 
The solution may be boiled until about one- 
fourth is evaporated and then made up to a liter 
with ammonium-free water. It will still furnish 
some ammonium. Fox recommends to distill 50 
c. c. with 500 c. c. of absolutely ammonium-free water, 
best twice distilled with sulphuric acid, and note the 
ammonia obtained. This quantity should be deducted in 
each analysis. The method of determining nitrogen by 
permanganate, as recommended by the A. A. A. S., 
avoids the necessity for this preliminary valuation of the 
solution. 
Fig. 5. 
Analytic Process:— 
The retort and condenser are thoroughly rinsed with 
ammonium-free water, 500 c. c. of the water to be tested 
introduced, about five c. c. of the sodium carbonate solu- 
tion added to render the water alkaline, and a piece of 
pumice-stone heated to redness and dropped in while hot. 
The water is then boiled gently until the distillate meas- 
ures 50 c. c. The distillate is transferred to one of the 
color-comparison cylinders and two c. c. of Nessler 
reagent added. A yellowish-brown color is produced, the 34 
ANALYTIC OPERATIONS. 
intensity of which is proportional to the amount of am- 
monium present. The full color is developed in five 
minutes. This color is exactly matched by introducing 
into another cylinder 50 c. c. of ammonium-free water, 
some of the standard ammonium chlorid solution, and two 
c. c. Nessler reagent, as before. According as the color 
so produced is deeper or lighter than that obtained from 
the water, other comparison liquids are prepared contain- 
ing smaller or larger proportions of the ammonium 
chlorid, until the proper color is produced. 
The distillation is continued, successive portions of 50 
c. c. each collected, and tested until no reaction occurs 
with Nessler reagent. The sum of the figures from the 
several distillates gives the total nitrogen obtainable as 
“ free ammonia,” so-called. 
If the quantity of ammonium is sufficient to cause a 
precipitate, the color comparison cannot be accurately 
made. In most cases this will not be of serious moment, 
as the quantity will be beyond the allowable limit. If 
accurate determination be desired, it may be made by 
dividing the first distillate into two equal parts, nessleriz- 
ing one of these, and then, if necessary, diluting the 
second part with ammonium-free water and nesslerizing 
this. 
Occasionally the evolution of ammonium hydroxid 
continues indefinitely, and may even increase with succes- 
sive distillates. This is due, not to ammonium compounds 
existing as such, but to decomposition of certain nitro- 
genous bodies, especially urea. In this case, it is not 
advisable to prolong distillation beyond the fourth or fifth 
distillate, but to proceed to the following part of the 
process. SANITARY EXAMINATIONS. 
35 
The residue in the retort serves for the determination 
of the nitrogen which is convertible into ammonium 
by alkaline potassium permanganate—the so-called “albu- 
minoid ammonia” of Messrs. Wanklyn, Chapman, and 
Smith. 
Fifty c. c. of alkaline permanganate solution are added 
to the retort, the distillation resumed, and the nitrogen 
estimated in each 50 c. c. as before, deducting that 
yielded by the permanganate. 
It is the practice of some analysts to mix the distillates 
of each of the above operations, and thus make deter- 
minations merely of the total nitrogen in each case. By 
so doing valuable information may be lost, since it has 
been pointed out by several observers, notably Mallet and 
Smart, that important information may be gained by 
observing the rate of evolution of the ammonium hy- 
droxid. Mallet has further pointed out that many waters 
may contain substitution ammoniums which may pass over 
before the addition of the alkaline permanganate, but not 
be correctly measured by nesslerizing. To avoid this 
source of error, he suggested that two determinations be 
made on each sample, one as above described and the 
other by the addition of alkaline permanganate without 
previous distillation. In this manner a higher figure will 
often be obtained than the sum of the figures from the 
two distillations by the other process. 
Since small quantities of ammonium compounds and 
nitrogenous matters are everywhere present, the greatest 
care should be exercised in order to avoid their introduc- 
tion in any way during the course of the analysis. All 
measuring vessels, cylinders, etc., should be thoroughly 
rinsed before using. The temperatures of the distillates 36 
ANALYTIC OPERATIONS. 
and standards should be approximately the same when the 
colors are compared. 
The Chemical Section of the American Association for 
the Advancement of Science recommends the following 
method for the application of the process embodying the 
results of recent investigations:— 
“Two hundred c. c. of distilled water, together with 10 
c. c. of the sodium carbonate solution, are distilled down 
to about 100 c. c. in the retort in which the analysis is to 
be conducted, and the last portion of 50 c. c. nesslerized 
to assure freedom from ammonium. Then 500 c. c. of the 
water to be examined are added and the distillation is 
carried on at such a rate that about 50 c. c. are collected 
in each succeeding ten minutes, and until a 50 c. c. meas- 
ure of distillate is obtained containing only an inappre- 
ciable quantity of ammonia. In nesslerizing, five minutes 
are to be allowed for the full development of color; 
after this, no change takes place for many hours. 
“ Now throw out the contents of the retort, rinse it 
thoroughly, put in 200 c. c. of distilled water and 50 c. c. 
of the permanganate solution, distill down to about 100 
c. c., and nesslerize the last portion of 50 c. c., to make 
sure of freedom from ammonia; add another portion of 
500 c. c. of the water under examination and proceed 
with the distillation and nesslerizing as with the first 
portion. 
“The difference between the ‘free’ ammonia of the 
first operation and the total ammonia of the second, is to 
be taken as the ‘albuminoid’ ammonia.” 
Bachman has described { Jour, of Amer. Chem. Soc., 
April, 1895) a process for determining nitrogen by per- 
manganate by using an apparatus which permits of the SANITARY EXAMINATIONS. 
37 
addition of the water in small and limited quantity to 
the full strength of permanganate solution at about the 
rate of distillation, so that at no time does it act upon a 
large volume. The apparatus consists of a flask of one 
liter capacity, fitted by a ground joint to a hollow cap 
carrying two upright tubes, each provided with a stop- 
cock, and to which cap also is attached the tube through 
which the distilled vapors pass to the condenser. Of the 
two upright tubes, one has a capacity of 50 c. c., and its 
end reaches through the cap to within three inches of the 
bottom of the distillation flask. The other has a capacity 
of 250 c. c., and its tube projects to within one-half of 
the bottom. The condensing apparatus is a closely-coiled 
glass worm, with a long projection at the lower extremity 
which passes through a soft rubber cork, inserted in a 
receiver. Through this cork also there is connected a 
Will and Varrentrap ammonium-absorption bulb. All con- 
nections should be tight without the use of a lubricant. 
The arrangement can be made movable so as to be raised 
from the bath if necessary. Bachman employs a bath of 
salt water, but it is not unlikely that a low temperature 
burner would answer every purpose. 
The procedure is as follows : After thoroughly rinsing 
the apparatus with ammonium-free distilled water, 500 c. c. 
of the water under examination with the addition of a 
little sodium carbonate if needed, are put into the flask. 
The Will and Varrentrap bulb is charged with Nessler 
solution, and the free end of the bulb connected with 
an exhaustion apparatus. A partial vacuum is estab- 
lished gradually, and the distillation carried on until 200 
c. c. have passed over. The vacuum-tube is disengaged 
and 250 c. c. of the liquid in the distilling flask drawn 38 
into the larger upright tube, and 50 c. c. of alkaline per- 
manganate solution which has been previously placed in 
the small tube, allowed to run in, after the flask to receive 
the distillate has been again attached. This arrangement 
gives 50 c. c. of alkaline permanganate acting on 50 c. c. 
of water, and after 30 or 40 c. c. have been distilled over 
the water in the larger tube is allowed to drop in at the 
same rate as the distillation, which must not exceed 50 c. c. 
in 15 minutes. This is continued until from 250 to 300 
c. c. have been distilled over, which is then nesslerized. 
For nesslerizing and other color comparisons, 
many forms of apparatus have been proposed. 
One of the simplest is that devised by Hehner, 
shown in Fig. 6. It consists of a graduated 
cylinder with a stopcock near the base, by 
which the liquid can be drawn down at will. 
Two such cylinders may be used, one for the 
nesslerized distillate, the other for the com- 
parison liquid. The darker liquid is drawn 
out until the tints are equal, when the relative volumes 
remaining will give the data for calculation. 
ANALYTIC OPERATIONS. 
Fig. 6. 
Several processes for the determination of the organic 
nitrogen in water, based on those in use in ordinary organic 
analysis, have been devised. That of Frankland and Arm- 
strong requires complex and extensive apparatus and spe- 
cial skill, has been shown also to be liable to inaccuracies, 
and has not come into extended use. 
TOTAL ORGANIC NITROGEN. 
The ease and certainty with which the nitrogen of most 
organic bodies may be converted into ammonium sulphate 
by boiling with sulphuric acid, offers a means of determina- SANITARY EXAMINATIONS. 
39 
tion free from the objections of former methods. The 
method introduced by Kjeldahl for general organic analy- 
sis, was first successfully applied to water analysis by Drown 
and Martin (Technology Quarterly, n, 3). 
In their original process 500 c. c. was concentrated to 
about 300 c. c., and the distillate nesslerized for determin- 
ing the nitrogen existing as ammonium compounds. The 
organic nitrogen is then determined in the residual water. 
Owing to the fact that in many waters the organic matter 
is decomposed by boiling, there is liability to under- 
estimation of the nitrogen. It is best, therefore, to de- 
termine at once the total unoxidized nitrogen, and esti- 
mate, without distillation, on a separate portion of the 
sample, the nitrogen that exists in ammonium compounds. 
The procedure is as follows : — 
Reagents Required:— 
Concentrated Sulphuric Acid.—This should be as free as 
possible from nitrogen. It can be obtained containing 
only 0.015 mgm. in 10 c. c. 
Sodium Hydroxid Solution.—The white granulated caus- 
tic soda sold for household use will answer ; 350 grams are 
dissolved in water and made up to 1000 c. c. 
Sodium Carbonate and Hydroxid Solution.—25 grams of 
each are dissolved in 250 c. c. of distilled water, and the 
solution boiled down to 200 c. c., to free it from ammonium. 
Analytic Process : — 
Determination of Nitrogen Existing as Ammonium.—200 
c. c. of the water are placed in a stoppered bottle, two c. c. 
each of the solutions of sodium carbonate and sodium 
hydroxid added, the stopper inserted, the solutions mixed 
and allowed to stand for an hour or two. A filter is pre- 
pared by inserting a rather large plug of absorbent cotton ANALYTIC OPERATIONS. 
40 
in a funnel. This should be washed with ammonium- 
free water until the filtrate gives no color with Nessler 
reagent. The clear portion of the sample is drawn off 
with a pipette and run through the filter, the first portions 
being rejected, since it is diluted by the water retained 
in the cotton. The filtration is rapid, and when 100 
c. c. of the liquid have passed through it is nessler- 
ized. If but little ammonium is present, a narrow tube 
about 60 centimeters long should be used for observing 
the color. 
Estimation of the Total Organic and Ammoniacal Nitro- 
gen.—500 c. c. of the water are placed in a round-bottomed 
Bohemian glass flask, 10 c. c. of concentrated sulphuric acid 
added, and a piece of pumice-stone is heated to bright red- 
ness and dropped in while hot. The liquid is boiled until 
the acid is colorless or very pale, the boiling being con- 
tinued for nearly an hour from this point. The flask is 
then removed from the flame, allowed to cool, and about 
250 c. c. of ammonium-free water added. 50 c. c. of the 
sodium hydroxid solution should be placed in the distil- 
ling apparatus, Fig. 3, about 250 c. c. of water added, a 
piece of red-hot pumice-stone dropped in and the liquid 
distilled until the distillate is free from ammonium. It is 
best to distill until the retort contains not more than 100 
c. c. The sulphuric acid solution is then poured in slowly, 
by means of a funnel, the stem of which touches the side 
of the retort, so that the two liquids do not mingle. The 
stopper of the retort is inserted, the liquids mixed by gentle 
agitation, and distilled. If much ammonium is present it 
is advisable to distill the first portion into about 10 c. c. of 
very dilute (1 : 1000) sulphuric acid, a piece of glass tube 
being connected to the condensing worm so that the lower SANITARY EXAMINATIONS. 
41 
end dips below the surface of the liquid. The distillates 
are collected and nesslerized in the usual way. 
A blank experiment should be made to determine the 
amount of ammonium in the sulphuric acid. 
NITROGEN AS NITRATES. 
Solutions Required :— 
A. H. Gill {Jour, of Amer. Chem. Soo., 1894), has 
subjected the various indirect methods of estimating 
nitrates to comparative examination, and prefers the 
following reagents :— 
Phenoldisulphonic Acid.—Strong sulphuric acid and pure 
phenol are mixed in the proportion of 37 grams of the 
former to three grams of the latter, and heated for six 
hours in, not upon, the water-bath. The resulting com- 
pound usually solidifies to a white mass on standing, but 
can be easily liquified on the water-bath during the evapo- 
ration of the samples to be tested. 
Standard Potassium Nitrate.— 0.722 gram of potassium 
nitrate, previously heated to a temperature just sufficient 
to fuse it, are dissolved in water, and the solution made up 
to 1000 c. c. One c. c. of this solution will contain .0001 
grin, of nitrogen. 
Analytic Process:— 
A measured volume of the water is evaporated just to 
dryness in a porcelain basin about six cm. in diameter. 
One c. c. of the phenoldisulphonic acid is added and thor- 
oughly mixed with the residue by means of a glass rod. 
The liquid is then diluted with about 25 c. c. of water, 
ammonium hydroxid added in excess, and the solution 
made up to 50 c. c. 
The nitrate converts the phenoldisulphonic acid into 42 
ANALYTIC OPERATIONS. 
picric acid, which by the action of the ammonium hy- 
droxid forms ammonium picrate; this imparts to the 
solution a yellow color, the intensity of which is propor- 
tional to the amount present. 
One c. c. of the standard solution of potassium nitrate 
is now similarly evaporated in a platinum basin, treated as 
above, and made up to 50 c. c. The color produced is 
compared to that given by the water, and one or the other 
of the solutions is diluted until the tints of the two agree. 
The comparative volumes of the liquids furnish the neces- 
sary data for determining the amount of nitrate. 
Mr. Gill has furnished me with an account of the method 
pursued at the Massachusetts Institute of Technology for 
obtaining a comparison liquid. Ten c. c. of the standard 
nitrate solution is cautiously evaporated, spontaneously or 
in a desiccator, and three c.c. of the phenoldisulphonic acid 
added, the mixture diluted with water to exactly 1000 c. c. 
Of this solution, portions are measured out with a finely 
and accurately graduated pipette into the porcelain dish 
similar to that in which the water-sample has been evapo- 
rated, water added to make exactly io c. c. and then two 
or three drops of ammonium hydroxid to make the 
liquid alkaline. The quantity of liquid taken in the pipette 
has the following values in parts per million of nitrogen as 
nitrates : io c. c. = x.o ; 5 c. c. = 0.5 ; 2 c. c. — o. 2; o 5 
c. c. = o.o5. Comparison is thus made directly in the dishes. 
In case of doubt the liquids are compared in tubes similar 
to nesslerizing tubes, but cut down to hold 15 or 20 c. c. 
The results obtained by this method are satisfactory. 
Care should be taken that the same quantities of phenoldi- 
sulphonic acid are used for the water and for the compari- 
son liquid. SANITARY EXAMINATIONS. 
43 
With subsoil and other waters probably containing much 
nitrates, io c. c. will be sufficient; but with river and spring 
waters, 25 c. c. may be used. When the organic matter is 
sufficient to color the residue, it will be well to purify the 
water by addition of aluminum hydroxid and filtration, 
before evaporating. 
Chlorin interferes with the accuracy of the test, but Gill 
finds that when not amounting to more than 20 parts per 
million it does not impair the practical value of the results. 
When greater than this, it is best to evaporate in vacuo over 
sulphuric acid. If the chlorin be more than 70 parts per 
million it should be considerably reduced by the addition 
of silver sulphate, which has been ascertained to be free 
from nitrates. Nitrites do not influence the reaction. 
The following is the process for determining nitrogen as 
nitrates (and nitrites) recommended by the Chemical Sec- 
tion of the A. A. A. S. It depends upon conversion into 
ammonium by the copper-zinc couple, and subsequent 
nesslerizing. It is inferior to the phenoldisulphonic acid 
method, both in convenience and accuracy, and does no* 
exclude the influence of nitrites. 
Take two wide-mouth glass-stoppered bottles, each hold- 
ing 250 c. c. and a piece of sheet zinc as long and about as 
wide as the bottles are deep from the shoulder down ; clean 
the zinc by dipping in dilute acid and washing with water 
and make it into a loose coil by rolling it round a piece of 
glass tube. Immerse it in a 1.4 to 1.8 per cent, solution 
of cupric sulphate in ammonia-free water, and leave it 
there until its surface is well covered with a continuous 
layer of the black copper; lift it out carefully, cover it 
in a beaker with successive portions of ammonia-free 
water, lifting it out and draining each time, and at once ANALYTIC OPERATIONS. 
44 
put it into one of the bottles of acidified water, prepared 
as follows :— 
Make 500 c. c. of the water to be examined distinctly 
acid with oxalic acid added in fine powder, with constant 
stirring, so that it shall dissolve readily, and pour half of 
the liquid into one of these 250 c. c. bottles, and half into 
the other, and leave them, stoppered, in a warm place for 
twenty-four hours. Then nesslerize both samples, decant- 
ing off the portions as wanted, from the precipitated earthy 
oxalates, and using double the usual quantity of Nessler’s 
solution, since the free oxalic acid has to be neutralized 
first by the alkali of the reagent. The proportion of am- 
monia may often be so large in the water in which the 
reduction is made, by the copper-zinc couple, that only 
five or ten c. c. can be taken for each test, and made up 
to 50 c. c. by the addition of ammonia-free water. The 
difference between the results with the two portions of 
water, gives the amount of nitrogen due to the oxidized 
nitrogen compounds in the water examined. 
NITROGEN AS NITRITES. 
The following is Ilosvay’s modification of Griess’s test. 
It has the advantage over the original method, that the 
color is developed more rapidly, and the solutions are not 
so liable to change. 
Solutions Required :— 
Paramidobenzenesulphonic Acid Solution (Sulphanilic 
Acid).—Dissolve 0.5 gram in 150 c. c. of diluted acetic 
acid, sp. gr. 1.04. 
a.-amidonaphthalene Acetate Solution.—Boil 0.1 gram of 
solid a-amidonaphthalene (naphthylamin) in 20 c. c. of 
water, filter the solution through a plug of washed SANITARY EXAMINATIONS. 
45 
absorbent cotton, and mix the filtrate with 180 c. c. of 
diluted acetic acid. All water used must be free from 
nitrites, and all vessels must be rinsed out with such water 
before tests are applied, since appreciable quantities of 
nitrites may be taken up from the air. 
Standard Sodium Nitrite.—0.275 gram pure silver 
nitrite are dissolved in pure water, and a dilute solution 
of pure sodium chlorid added until the precipitate ceases 
to form. It is then diluted with pure water to 250 c. c., 
and allowed to stand until clear. For use 10 c. c. of this 
solution are diluted to 100 c. c. It is to be kept in the dark. 
One c. c. of the dilute solution is equivalent to .00001 
gram nitrogen. 
The silver nitrite is prepared thus : A hot concentrated 
solution of silver nitrate is added to a concentrated solu- 
tion of the purest sodium or potassium nitrite available, 
filtered while hot and allowed to cool. The silver nitrite 
will separate in fine needle-like crystals, which are freed 
from the mother liquor by filtration by the aid of a filter 
pump. The crystals are dissolved in the smallest possible 
quantity of hot water, allowed to cool and again separated 
by means of the pump. They are then thoroughly dried 
in the water-bath, and preserved in a tightly-stoppered 
bottle away from the light. The purity may be tested by 
heating a weighed quantity to redness in a tared porcelain 
crucible and noting the weight of the metallic silver. 154 
parts should leave a residue of 108 parts silver. 
Analytic Process:— 
25 c. c. of the water are placed in one of the color-com- 
parison cylinders, and 2 c. c. each of the test solutions are 
dropped in. It is convenient to have a pipette for each 
solution, and to use it for no other purpose. 46 
ANALYTIC OPERATIONS. 
One c. c. of the standard nitrite solution is placed in 
another clean cylinder, made up with nitrite-free water to 
25 c. c. and treated with the reagents as above. 
In the presence of nitrites a pink color is produced. At 
the end of five minutes the two solutions are compared, 
the colors equalized by diluting the darker, and the calcu- 
lation made as explained under the estimation of nitrates. 
The reactions consist in the conversion of the sulphan- 
ilic acid into diazobenzenesulphonic anhydrid, by the 
nitrite present; this compound is then in turn converted 
by the amidonaphthalene into azo-a-amidonaphthalene- 
parazobenzene sulphonic acid. The last-named body gives 
the color to the liquid. 
OXYGEN-CONSUMING POWER. 
All organic materials being more or less easily oxidized, 
several methods have been suggested for determining the 
oxygen consuming powers of waters by treatment with 
active oxidizing agents. These methods are, however, 
limited in value. The organic matters in water differ 
much in character and condition, and their oxidability is 
subject to much variation, according to the circumstances 
under which the test is made. Nevertheless, as a high 
oxygen-consuming power certainly indicates departure from 
purity, some additional evidence may be obtained. Potas- 
sium permanganate is especially suitable. The test is 
usually made by introducing a known amount of the per- 
manganate into the water, which has been rendered acid, 
and measuring after a definite period the proportion which 
has been decomposed. 
It must not be overlooked that if a water contains 
nitrites, ferrous compounds, or sulphur compounds other SANITARY EXAMINATIONS. 
47 
than sulphates, the proportion of oxygen consumed will be 
greater than that required for the organic matter. It has 
been proposed, in order to remove the nitrites before 
applying the permanganate, to take 500 c. c. of the water, 
add 10 c. c. of the dilute sulphuric acid, boil for twenty 
minutes, allow to cool, and then treat with permanganate. 
Since, however, the amount of nitrites, if appreciable, can 
be directly determined, it is more satisfactory to deduct 
from the oxygen consumed the amount required to con- 
vert the nitrites present into nitrates, and the remainder 
will be that required for the other oxidizable ingredients. 
14 parts of nitrogen existing as nitrite require 16 parts of 
oxygen for conversion into nitrate. Similarly, 112 parts 
of iron in a ferrous compound will require 16 parts of 
oxygen for conversion to the ferric condition. 
Of the following methods the first is due in the main to 
Dr. Tidy, has been improved by Dr. Dupre, and is ap- 
proved by the Society of Public Analysts of Great Britain :— 
Solutions Required:— 
Standard Permanganate.—.395 gram pure potassium per- 
manganate are dissolved in distilled water, and the solution 
made up to 1000 c. c. One c. c. is equal to .0001 gram 
oxygen. 
Diluted Sulphuric Acid.—Add 50 c. c. of pure sulphuric 
acid to 100 c. c. of water, and then add solution of potas- 
sium permanganate until a faint pink color is obtained, 
which is permanent when the liquid is heated to 8o° 
Fahrenheit for four hours. 
Potassium Iodid.—10 grams of the pure salt recrystallized 
from alcohol are dissolved in 100 c. c. of distilled water. 
Sodiiwi Thiosulphate.—One gram of the pure crystallized 
salt dissolved in 2000 c. c. of distilled water. 48 
ANALYTIC OPERATIONS. 
Starch Indicator.—One gram of clean starch is mixed 
smoothly with cold water into a thin paste, then poured 
gradually into about 200 c c. of boiling water, the boiling 
continued for one minute, the liquid allowed to settle, and 
the clear portion used. It is best freshly prepared. 
Analytic Process :— 
Two determinations are made, one, of the oxygen con- 
sumed in fifteen minutes, which is considered to represent 
the nitrites, sulphids, or ferrous compounds, and the other 
of the oxygen consumed by four hours’ action. Both de- 
terminations are made at a temperature of 8o° F. Three 
glass stoppered bottles, of about 350 c. c. capacity, are 
rinsed with strong sulphuric acid, and then with water. In 
one is placed 250 c. c. of pure distilled water as a control 
experiment, and in each of the others 250 c. c. of the water 
to be tested. The bottles are stoppered and brought to a 
temperature of 8o° F.; 10 c. c. of the dilute sulphuric acid 
and 10 c. c. of the standard permanganate are added to 
each and the stoppers again replaced. At the end of 
fifteen minutes one sample of water is removed from the 
bath, and two or three drops of the potassium iodid solu- 
tion added to remove the pink color. After thorough 
admixture, the thiosulphate solution is run in from a burette 
until the yellow color is nearly destroyed, a few drops of 
the starch solution added, and the addition of the thiosul- 
phate continued until the blue color is quite discharged. 
If the addition of the thiosulphate solution has been 
properly conducted, one drop of the permanganate solu- 
tion will restore the blue color. 
The other bottles are maintained at 8o°F. for four hours. 
Should the pink color disappear rapidly in the bottle con- 
taining the water under examination, 10 c. c. of the per- SANITARY EXAMINATIONS. 
49 
manganate solution must be added to each bottle, in order 
to maintain a distinct pink color. At the end of four hours 
each bottle is removed from the bath, two or three drops 
of potassium iodid added, and the titration with thiosul- 
phate solution conducted as just described. The calcu- 
lation is most conveniently made as follows:— 
a = number of c. c. required for the control experiment. 
b — number of c. c. required for the water under exami- 
nation. 
c = available O in permanganate (.001 for 10 c. c.). 
x — oxygen consumed by water. 
Then, a : a—b : : c : x. 
The following method is recommended by the Chemical 
Section of the American Association for the Advancement 
of Science : — 
“Prepare a solution of potassium permanganate contain- 
ing o.i mgm. of available oxygen to one c. c. and a solu- 
tion of oxalic acid of such strength as to decompose the 
permanganate solution, volume for volume, the strength 
being re-determined from time to time. The water used 
for making these solutions should be purified by distillation 
from alkaline permanganate. 
“To 200 c. c. of water to be examined, in a 400 c. c. 
flask, add 10 c. c. of dilute sulphuric acid (1 : 3) and such 
measured quantity of the permanganate as will give a per- 
sistent color; boil ten minutes, add, if necessary, more 
permanganate in measured quantities so as to maintain the 
red color; remove the flask from the lamp, add 10 c. c. of 
oxalic acid solution to destroy the color, or more if 
required by the excess of permanganate, and then add per- 
manganate, drop by drop, till a faint pink tint appears. ANALYTIC OPERATIONS. 
From the total quantity of permanganate used deduct the 
equivalent of the oxalic acid used, and from the remainder 
calculate the milligrams of oxygen consumed by the oxid- 
izable organic matter in the water.” 
The oxygen-consuming power may also be indirectly 
estimated by the action of the organic matter upon silver 
compounds. H. Fleck’s method (Presenilis’ Quantitative 
Analysis, English edition), depends upon the reduction 
produced by boiling the water with alkaline solution of 
silver thiosulphate and estimation of the unreduced silver. 
A. R. Leeds (Lond., Edin. and Dub. Phil. Mag., July, 
1883) gives a method by treating the water with decinormal 
silver nitrate, exposing to light until it settles perfectly 
clear, and estimating the reduced silver in the deposit. 
These methods are open to practically the same objections 
as in the use of permanganate, and do not seem to possess 
any decided advantage. Qualitative results of some 
interest may occasionally be obtained by the following 
method: Twoc.c. of a one per cent.solution of silver nitrate, 
rendered decidedly alkaline by ammonium hydroxid, are 
added to 100 c. c. of the water in a stoppered bottle, which 
is then placed in full sunlight for two hours. Waters con- 
taining but little organic matter will not show at the end of 
this period any appreciable tint. The following results 
will show the character of the test:— 
Schuylkill water, .... no color. 
“ with 0.02 c. c. urine, . . red-brown. 
“ “ with o.oi c. c. urine, . . deep brown. 
“ “ witho.25gramrawsugar.no color. 
Well water, not perfectly pure, but 
not unfit to drink, .... faint black. 
“ “ markedly contaminated, . . black ppt. almost 
immediately. 
Water from a small stream quite pure, . . no color. SANITARY EXAMINATIONS. 
51 
PHOSPHATES. 
Solutions Required :— 
Ammonium Molybdate.—Ten grams of molybdic anhy- 
drid are dissolved in 41.7 c. c. of ammonium hydroxid, sp. 
gr. 0.96, and the solution is poured slowly, and with con- 
stant stirring, into 125 c. c. of nitric acid, sp. gr. 1.20, 
and allowed to stand in a warm place for several days, 
until clear. 
Analytic Process :— 
500 c. c. of the water are slightly acidified with nitric 
acid, and evaporated to about 50 c. c. A few drops of 
dilute solution of ferric chlorid are added and then 
ammonium hydroxid in slight excess. The precipitate, 
which contains all the phosphate, is filtered off and 
dissolved on the filter by the smallest possible quantity of 
hot dilute nitric acid. The filtrate and washings should 
not exceed five c. c.; if more, they must be evaporated to 
this bulk. The liquid is heated nearly to boiling, two c. c. 
of ammonium molybdate solution added, and the liquid 
kept moderately warm for half an hour. If the quantity 
of precipitate is appreciable, it is collected on a small 
weighed filter, washed with distilled water, dried at ioo° 
F. and weighed. The weight of the precipitate multiplied 
by 0.05 gives the amount of P04. If the quantity is not 
sufficient to collect in this manner, it is usually reported, 
according to circumstances, as “ traces,” “ heavy traces,” 
or “very heavy traces.” 
DISSOLVED OXYGEN. 
The method here given, a modification of Mohr’s, was 
proposed by Blarez. It is rapid and satisfactory. 52 
ANALYTIC OPERATIONS 
Solutions Required :— 
Sodium Hydroxid.—40 grams of pure sodium hydroxid 
to the liter. 
Ferrous-Ammonium Sulphate.—40 grams dissolved in 
about a liter of water, and acidified with a few drops of 
concentrated sulphuric acid. 
Decinormal Potassium Permanganate.—3*156 grams 
dissolved in a liter of distilled water. The accuracy of 
this solution should be determined by titration with a 
known weight of ferrous-ammonium sulphate. One c. c. 
should be equivalent to .0392 grm. ferrous-ammonium 
sulphate (.0008 gram of oxygen). 
The apparatus employed (shown in Fig. 7) is a globular 
separator, of about 250 c. c. capacity. Above the bulb is 
a caoutchouc stopper carrying a cylindrical funnel, of about 
12 c. c. capacity, terminating in a tube, 8 mm. calibre, 
sharply contracted at the outlet to a capillary 
opening. The tube should project about 6 mm. 
below the stopper. The exact capacity of the 
apparatus is measured as follows : The bulb is 
completely filled with water and the stopper 
inserted ; the level of the water will rise slightly 
in the funnel tube, and should be brought down 
to its outlet by drawing a little off at the stop- 
cock, after which the water is run into a 
graduated measure and its volume noted. 
Analytic Process :— 
35 c. c. of mercury and 10 c. c. of sodiun 
hydroxid solution are put into the bulb, anc 
then sufficient of the water to be tested to 
fill it. The funnel stopper is inserted and the wate 
which rises into the funnel brought into the bulb by 
Fig. 7. SANITARY EXAMINATIONS. 
53 
cautiously running out at the stopcock, mercury, the 
volume of which should be noted. The exact volume of 
water used is thus known. Five c. c. of the ferrous- 
ammonium sulphate solution are poured into the funnel, 
brought into the bulb by running out mercury, and the 
liquid thoroughly mixed by giving the apparatus a gyratory 
movement. After standing five or six minutes the oxygen 
will be completely absorbed ; io c. c. of the diluted sul- 
phuric acid are now added by the same method. On 
agitating the bulb the contents become clear. The watery 
liquid is then transferred to a beaker and titrated with 
decinormal permanganate. A volume of water equal to 
that used in the test is poured into another beaker, io c. c. 
each of the sodium hydroxid and diluted sulphuric acid 
added, and then five c. c. of ferrous-ammonium sulphate 
solution. The resulting liquid is titrated with permanga- 
nate. The weight of oxygen corresponding to the 
difference between the two titrations gives the weight of 
dissolved oxygen in the liquid employed. From this 
should be subtracted as correction the amount of oxygen 
dissolved by a volume of water equal to that of the sodium 
hydroxid solution used. This is found by reference to 
the table in the appendix. The amount of oxygen dis- 
solved in the sulphuric acid has no appreciable effect. 
Nitrates do not appear to impair the accuracy of this 
method, and the interfering action of nitrites and other 
reducing compounds is avoided by the control experiment 
as detailed. 
It is perhaps hardly necessary to add that the exact tem- 
perature of the water is to be noted at the time of collec- 
tion of the sample. 
In transferring to the bulb, the water should be agitated 54 
ANALYTIC OPERATIONS. 
as little as possible in contact with the air, in order to 
avoid the absorption of oxygen. A siphon should be used 
for this purpose, the lower end being allowed to reach to 
the bottom of the bulb. 
The following modification is suggested as being especi- 
ally suitable for poorly oxygenated waters: An accu- 
rately stoppered bottle, the exact capacity of which is 
known (about 500 c. c. is a convenient size), is completely 
filled at the source with the water to be examined, and the 
stopper inserted so as to drive out all air. The stopper is 
removed in the laboratory, 50 c. c. of the water drawn off 
with a pipette, and the water covered immediately with a 
layer of gasoline previously purified by shaking up several 
times with a solution of potassium permanganate and di- 
luted sulphuric acid, and washed several times with water. 
The sodium hydroxid, ferrous-ammonium sulphate, and 
sulphuric acid are introduced into the water by means of 
burettes to which long glass delivery tubes are attached. 
The titration with potassium permanganate is conducted 
in the same way. The liquid is mixed from time to time, 
as the solutions are added, by means of a glass rod. In 
this way the air may be completely excluded throughout 
the entire operation. The amount of water titrated is, of 
course, equal to the whole capacity of the bottle, less the 
50 c. c. removed by the pipette. 
The control experiment on an equal volume of the water, 
and the correction for the oxygen added with the sodium 
hydroxid solution, are made as detailed above. 
Dupre has employed the determination of free oxygen 
for the estimation of the proportion of oxygen-consuming 
microbes. The principle of the method is that pure water, 
if kept in a closed bottle, will neither gain nor lose oxygen SANITARY EXAMINATIONS. 
55 
in any length of time, but if organisms capable of causing 
absorption of oxygen are present, the quantity will de- 
crease. 
The experiment is carried out by placing a sample of 
the water in a clean bottle, and vigorously shaking it to 
saturate with air. A clean 250 c. c. bottle is completely 
filled with the water, tightly stoppered, and maintained at 
a temperature of 68° F. for ten days; the free oxygen re- 
maining is then determined. 
POISONOUS METALS. 
Under this conventional title are included barium, 
chromium, zinc, arsenum, copper, and lead; manganese, iron, 
aluminum also, though not usually classed in this group, 
are objectionable when present in notable amounts. 
Barium is rarely present, and only in water containing 
no sulphates. It can be detected and estimated by slightly 
acidifying the water with hydrochloric acid, filtering if 
necessary, and adding solution of calcium sulphate. The 
precipitated barium sulphate is collected and weighed in 
the usual way. 
Chromium is rarely present, but may be looked for in 
the waste waters of dye works and similar sources. To 
detect it, a considerable volume of the water is evaporated 
to dryness with addition of a small amount of potassium 
chlorate and nitrate, transferred to a porcelain crucible and 
brought to quiet fusion ; any chromium present will be 
found in the residue in the form of chromate. The fused 
mass, after cooling, is boiled with a little water, filtered, 
the filtrate rendered slightly acid with hydrochloric acid, 
and a solution of hydrogen dioxid added. In the pres- 
ence of chromium a transient blue color will appear; by 56 
ANALYTIC OPERATIONS. 
adding a little ether, and shaking the mixture the color 
will pass into the ether, and on standing will form a blue 
layer on the surface of the water. 
Zinc is best detected by the test described by Allen. 
The water is rendered slightly alkaline by addition of 
ammonium hydroxid, heated to boiling, filtered, and the 
clear liquid treated with a few drops of potassium ferro- 
cyanid; in the presence even of the merest trace of zinc 
a white precipitate will be produced. 
Arsenum is most readily detected by Reinsch’s test. 
One liter of the water is rendered slightly alkaline by pure 
sodium carbonate, and evaporated nearly to dryness in a 
porcelain basin. Two or three c. c. of water strongly acidu- 
lated with hydrochloric acid are placed in a small test-tube, 
about square centimeter of bright copper foil is added, 
and the liquid boiled gently for a few moments. If the 
copper remains bright, showing that the reagents contain 
no arsenum, the water-residue is acidified with hydrochloric 
acid, added to the contents of the test-tube, and the liquid 
again boiled for several minutes. If arsenum be present, 
a steel-gray stain will appear on the copper. The slip is 
removed, washed with distilled water, thoroughly dried by 
pressure between filter paper, inserted into a narrow glass 
tube closed at one end, which has been previously dried by 
heating nearly to redness. The tube is gently heated at 
the point at which the copper rests; the deposit will 
sublime and collect on the cooler portion of the tube, in 
crystals which the microscope shows to be octahedral. 
Since small amounts of arsenum frequently occur in 
reagents and in glass vessels, care must be taken to avoid 
such sources of error. Sodium carbonate solution may 
contain arsenum dissolved from the glass bottle in which SANITARY EXAMINATIONS. 
57 
it is kept. It is best, therefore, to use the solid carbonate 
for rendering the water alkaline, and to determine its 
purity before use. 
Iron is detected by the addition of a drop of ammonium 
sulphid to the water in a tall glass cylinder. Ferrous sul- 
phid is formed, having a greenish-black color, instantly 
discharged by acidifying the water with dilute hydrochloric 
acid. A still better test is the production of a blood-red 
color, with potassium thiocyanate, due to the formation 
of ferric thiocyanate. The water should be first boiled 
with a few drops of nitric acid, to convert the iron to the 
ferric condition, cooled, and a drop or two of the solution 
of potassium thiocyanate added. The test is very deli- 
cate. Either of the above tests may be made quantitative 
by matching the color produced in ioo c. c. of the water 
with that obtained from a known weight of iron. The 
method with potassium thiocyanate is preferable, as it is 
more delicate and there are fewer interfering conditions. 
The following is the method as elaborated by Thompson 
and described in Sutton’s “Volumetric Analysis: ”— 
Solutions Required:— 
Standard Ferric Sulphate.—0.7 gram ferrous ammonium 
sulphate are dissolved in water acidified with sulphuric 
acid, and potassium permanganate solution added until the 
solution turns a very faint pink color. The solution is 
diluted to a liter. One c. c. contains o. 1 milligram iron. 
Diluted Nitric Acid.—30 c. c. concentrated nitric acid 
diluted with water to about 100 c. c. 
Potassium Thiocyanate.—Five grams of the salt dissolved 
in about 100 c. c. water. 
Analytic Process:— 
About 100 c. c. of the water are evaporated to small bulk, 58 
ANALYTIC OPERATIONS. 
acidified with hydrochloric acid, and just sufficient dilute 
potassium permanganate solution added to convert all the 
iron to the ferric condition. The liquid is evaporated 
nearly to dryness to drive off excess of acid, then diluted 
to its original volume, ioo c. c. In two tall glasses 
marked at xoo c. c., five c. c. of the nitric acid and 15 
c. c. of the thiocyanate solution are placed. To one of 
these a measured volume of the treated water is added and 
both vessels filled up to the mark with distilled water. If 
iron is present, a blood-red color will be produced. Stand- 
ard iron solution is added to the second vessel until the color 
agrees. The amount of water which is added to the first 
glass will depend upon the quantity of iron it contains; 
not more should be used than will require two or three c. c. 
of the standard to match it, otherwise the color will be too 
deep for comparison. 
Manganese.—The following method is described by 
Wanklyn in his treatise on water-analysis. About one liter 
of the water is evaporated to small bulk, nearly neutralized 
by hydrochloric acid and treated with a few drops of a 
solution of hydrogen dioxid. The formation of a brown 
precipitate indicates the presence of manganese. The test 
is very delicate. The precipitate may be collected on 
a filter, the filter ashed, and the residue fused with a mix- 
ture of sodium carbonate and potassium nitrate. Green 
potassium manganate will be produced, which, when boiled 
with water, will give a bright red solution of potassium 
permanganate. The quantitative determination is given 
elsewhere. 
Aluminum.—Traces of this element are to be ex- 
pected in all waters, and it is not usual to test for it except 
in elaborate analysis of the mineral ingredients, as de- SANITARY EXAMINATIONS. 
59 
scribed in another section. The use of aluminum sulphate 
as a coagulant in many rapid-filtration methods makes it 
necessary to examine effluents for excess of precipitant, and 
this may be done by the following method devised by Mrs. 
Richards:— 
To 25 c. c. of the water to be tested (concentrated from 
one liter or more, if necessary) is added a few drops of 
freshly prepared logwood decoction ; any alkali is neutra- 
lized and the color is brightened by the addition of two 
or three drops of acetic acid. By comparison with 
standard solutions, the amount of alum present may be 
determined. One part of alum in 1,000,000 of water can 
be detected with certainty. In cases of greater dilution 
concentration of several liters may be necessary to obtain 
a decisive test. The logwood chips yield the right color 
only after having been treated with boiling water two or 
three times, rejecting the successive decoctions. The first 
portion gives a yellow color, the third or fourth usually 
a deep red. 
Lead may be readily detected by adding to the water in 
a tall glass cylinder a drop of ammonium sulphid; brown- 
ish black lead sulphid is formed, which does not dissolve 
either by acidulating the water with dilute hydrochloric 
acid (distinction from iron), nor by the addition of about 
one c. c. of a strong solution of potassium cyanid (dis- 
tinction from copper). S. Harvey (Analyst, April, 1890) 
gives the following method for detecting lead in water: 
250 c. c. are placed in a conical precipitating jar, about 
0.1 gram of crystallized potassium dichromate is added 
and dissolved by agitation. The same volume of lead-free 
water is treated in the same manner, and the two solutions 
placed side by side. Water containing 0.3 parts per mil- 60 
ANALYTIC OPERATIONS. 
lion, will show a turbidity in 15 minutes which will be 
rendered more distinct by contrast with the clear water 
alongside. By allowing the jar to stand for about twelve 
hours undisturbed, the precipitate will settle and will be- 
come still more distinct. No other metal likely to be pres- 
ent in water will give a similar reaction. 
In the absence of copper the amount of lead present 
may be determined as follows: A solution is prepared con- 
taining 1.6 grams of lead nitrate to the liter; one c. c. of 
this contains one milligram lead. 100 c. c. of the water to 
be tested are placed in a tall glass vessel, made acid by the 
addition of a few drops of acetic acid and five c. c. of 
hydrogen sulphid added. In a similar vessel 100 c. c. of 
distilled water are placed, together with the same quantities 
of acetic acid and hydrogen sulphid, and sufficient of the 
standard lead solution to match the tint in the first cylin- 
der. The amount of lead in the water under examination 
is thus known. 
Copper is detected in the same manner as lead by 
acidifying the water with acetic acid and adding hydrogen 
sulphid. The precipitate is distinguished from lead 
sulphid by the fact that the color is discharged on the 
addition of about one c. c. of a strong solution of pure 
potassium cyanid. It may be further confirmed by the 
addition to another portion of the water of a solution of 
potassium ferrocyanid. In the presence of even a very 
small amount of copper, a mahogany red color is pro- 
duced. 
In the absence of lead, copper is estimated in the same 
way as that metal, using, however, a standard solution of 
copper for the comparison liquid. This is made by dis- 
solving 3.929 grams of crystallized copper sulphate in one SANITARY EXAMINATIONS. 
6i 
liter of water. One c. c. of the solution contains one 
milligram copper. 
If both lead and copper are present, a large quantity of 
the water should be evaporated to small bulk, and the 
metals separated and estimated by any one of the ordinary 
laboratory methods. 
The following table, prepared by A. J. Cooper, indicates 
the comparative delicacy of some of the ordinary tests for 
the detection of poisonous metals in water: — 
Metal. 
Reagent. 
Depth of Liquid, inches. 
Depth of Liquid, 14% inches. 
Cylinder enclosed in opaque 
tube. 
Copper, . . 
K4Cy„Fe 
1 part of metal detected in 
4,000,000 of water. 
1 part of metal detected in 
II>75°>000 of water. 
“ 
NH.HO 
1,000,000 “ 
1,950,000 
“ 
H 2S 
4,150,000 “ 
15,660,000 “ 
Zinc, . . . 
NH.HS 
2,500,000 “ 
Arsenic, . . 
H2S 
3,600,000 “ 
7,520,000 (t 
Lead, . . 
K2Cr04 
4,000,000 “ 
5,875,000 “ 
h2s 
100,000,000 “ 
196,000,000 “ 
BIOLOGIC EXAMINATIONS. 
In a comprehensive sense the living organisms of water 
include representatives of all the great groups of animals 
and plants. The presence of any of the higher orders of 
organic forms may be taken as an indication of moderate 
purity, as these are absent from very foul water. From an 
analytic point of view, observation is limited to the deter- 
minations of those forms which are inappreciable to the 
unassisted eye. As far as regards some of the moderately 
complex organisms, such as the minute crustaceans, algae, 
desmids, and even the amebae, it may be said that while 
some general inferences as to the character and history of 62 
ANALYTIC OPERATIONS. 
the water may be deduced from an identification of the 
specific forms, no definite sanitary signification can be 
attached to them. The ova of the entozoa might in some 
cases be detected by careful search, and would indicate 
recent pollution of a highly dangerous character. 
Cohn (Beitr. z. Biol. d. Pflanz.) regards chlorophyl- 
producing plants (diatoms and green algae), together with 
the infusoria that feed upon them, and species of entomos- 
traca (Daphnia and Cyclops), when present in only moder- 
ate amounts, as indicating water not very rich in dissolved 
organic matter. Species of Cladothrix, Crenothrix and 
Beggiaioa, which are among the larger bacteria, and fre- 
quently appear as branching forms, indicate suspended 
organic matter; while dissolved organic matter in a state 
of active decomposition is indicated by the presence of 
ordinary bacteria (Bacilli, Spirilla), etc. 
Cladothrix dichotoma withdraws iron from water, and 
fixes it, causing obstructions in iron water pipes. Creno- 
thrix Kiiliniana Rabenhorst, is seen in water containing 
iron and sometimes causes a disagreeable odor. 
The number of the higher forms present in any sample 
will depend very much upon the point at which it is col- 
lected, they being more numerous in the neighborhood of 
large plants and at the bottom and sides of streams. 
Under our present knowledge, no pathogenic power can 
be assigned to the higher forms of organic life, except 
entozoa, but their bodies after death may indirectly con- 
tribute to the rapid increase of the bacilli proper, by serving 
as food. 
Several observers, notably Sedgwick and Rafter, have 
paid considerable attention to the recognition of the ani- 
mal and vegetable forms in surface-waters. Some of these SANITARY EXAMINATIONS. 
63 
forms, while not apparently directly disease-producing, 
cause disagreeable odors and colors in water; in the 
warm season of the year when these waters are stored in 
reservoirs, considerable annoyance is felt by the users, and 
the engineer-in-charge is subjected to much criticism. 
For some years the American Water works Association has 
had a special committee engaged in collecting data bearing 
upon this point, and devising methods for preventing the 
conditions. No satisfactory explanation or remedy has 
yet been offered by this committee, but it has been found 
that even crude filtration-methods, such as allowing the 
water to pass through a dike of porous soil before storing 
it in a reservoir, will diminish the tendency to these con- 
ditions. Cleansing a reservoir, disinfecting the inner sur- 
face, for instance, by whitewashing, has also improved the 
condition. (See Addenda, p. 136.) 
A summary of Sedgwick’s method, with some modifica- 
tions by Dr. Williston, is given by the latter in a Report 
on Connecticut water-supplies for 1889-90. 
In ordinary cases about ioo c.c. are employed. Some- 
times it will be advantageous to use double this quantity, 
at other times much less. In rare cases the examination 
can be made upon unfiltered water. Originally sand was 
employed for a filter material, but Williston finds that 
precipitated silica made by decomposing silicon fluorid 
with water is more satisfactory. This precipitated silica is 
a commercial article, and its method of preparation is 
given in all the larger manuals of chemistry. 
A small glass funnel with an even-calibered stem is 
selected, and the lower end of the stem plugged with a 
little absorbent cotton, upon which a layer three or four 
mm. deep of the filter-material is placed. The requisite 64 
ANALYTIC OPERATIONS. 
volume of water is then allowed to filter through. The 
pledget of cotton is removed, and the filter-material is 
washed down with filtered or distilled water into a cell 
intended for microscopic examination. This cell is a glass 
plate accurately ruled, to which is attached a brass cell 50 
mm. long by 10 mm. wide, of depth sufficient to hold 
about two c.c. of water. After the material has been 
allowed to distribute itself and settle in the cell, it is 
examined with a moderate power, and the different organ- 
isms in a varying number of the squares counted. Each 
organism may be counted by itself, if occurring in large 
numbers, the average of a few squares being sufficient for 
the purpose. Organisms less numerously represented may 
be counted by averaging a larger number of squares. 
Filtering in this manner cannot be relied upon in all 
cases. Indeed, in most cases the unfiltered water also 
should be examined. Some of the minute unicellular 
organisms pass readily through the small extent of sand or 
precipitated silica, or even through filter paper. 
It is not unlikely that the high-speed centrifugal appara- 
tus now used in laboratories, associated with the employ- 
ment of some fine precipitant will aid in these investiga- 
tions. (See Addenda, p. 136.) 
The introduction of the ova of entozoa into the human 
system by means of water is doubtless a very common 
occurrence, and cases have been reported. One of the 
most striking of these was the anemia occurring among the 
workmen in the St. Gothard tunnel, which was found to 
be due to the ingestion of the ova of a parasitic animal, 
A nchylostomum duodenale. 
Culture Media.—For bacteriologic examinations, cul- 
ture media prepared with gelatin or agar-agar, are gen- SANITARY EXAMINATIONS. 
65 
erally used. In special cases potatoes and blood-serum are 
employed. In all cases solutions and vessels must be 
thoroughly sterilized. This is most easily accomplished in 
the Arnold steam sterilizer. It consists of a copper boiler, 
in the form of an inverted funnel, which communicates 
with the sterilizing chamber. A double casing is so 
arranged that the condensed steam falls into the pan and 
returns to the boiler. This pan should be about half-filled 
with water before starting. This apparatus is suitable not 
only for all sterilizations, but also for preparing solutions 
and for hot filtrations. 
Aleut- extract-peptone-gelatin :— 
Water, .... . 1000 c.c. 
Meat extract, 5 grams 
Gelatin, 150 “ 
Peptone, 10 “ 
Glucose, 2 “ 
The materials, which should be of good quality, are dis- 
solved by heat and the solution rendered slightly alkaline 
by the addition of sodium carbonate or trisodium phos- 
phate, added by small portions, stirring between each 
addition, and testing the liquid by placing a drop of it on 
red litmus paper. When the alkaline reaction appears, the 
liquid is filtered through good filter paper, the funnel and 
beaker being placed in the sterilizer, and a gentle steaming 
maintained in order to keep the gelatin liquid. 
In place of meat extract, a solution may be made as fol- 
lows: macerate 500 grams of finely minced lean meat in 
1000 c.c. of water, for twenty four hours, at a temperature 
not over 450 F. Strain the liquid, add five grams of 
common salt and the peptone, gelatin and glucose, and 
render feebly alkaline, as before. (See Addenda, p. 137.) 66 
ANALYTIC OPERATIONS. 
Agar-agar Mixture.—When cultures are to be conducted 
at a temperature above 68° F., agar-agar must be used as 
gelatinizing ingredient. The solution is prepared as given 
above, except that only 15 grams of agar-agar must be 
used and a much longer time will be required for its solu- 
tion. The operation can be facilitated by soaking the 
agar-agar for twelve hours in a strong solution of common 
salt, or by the following treatment, which was first described 
by Mace : — 
Twenty grams of agar-agar, cut fine, are steeped for 
twenty-four hours in 500 c.c. of water, containing six per 
cent, of hydrochloric acid, with occasional stirring. It is 
then well washed, and placed for a similar period in the 
same amount of water, to which six per cent, of ammonium 
hydroxid has been added. It is again washed thoroughly 
and added to 1000 c.c. of boiling water. It dissolves at 
once. The peptone, gelatin and salt can then be added, 
the mixture rendered feebly alkaline and filtered in the 
sterilizer. 
Agar-agar Gelatin.—To secure the advantages of both 
agar-agar and gelatin, a solution may be made by dissolv- 
ing 50 grams of gelatin and 7.5 grams of agar-agar in a 
liter of water, adding the peptone, etc., in the usual pro- 
portions, rendering alkaline, filtering and sterilizing. The 
proportions of agar-agar and gelatin must be adhered to 
closely or the gelatinization maybe lumpy and incomplete. 
Potato Culture.—Cultivation on potatoes was once much 
used as a method of distinguishing certain microbes. 
Large, sound potatoes should be selected, thoroughly 
washed, and cut into disks about five cm. in diameter and 
one cm. thick. These are placed in glass boxes (pomade 
boxes) which have lids with ground joint, and heated for SANITARY EXAMINATIONS. 
67 
about one-half hour in the sterilizer. Another method is 
to cut out cylinders with the aid of an apple-corer, or 
largest size cork-borer, slice these obliquely, and place 
them in test-tubes, which are then closed with cotton plugs, 
and sterilized. The latter method does not give a large 
surface, but the growth of any inoculation may be easily 
watched. 
Collection of Samples.—Bacteriologic examinations 
are of little value unless promptly made on samples that 
have been collected with precautions against contamina- 
tion. The inoculation of the culture-medium is best done at 
the source. If this is not possible, glass-stoppered bottles 
holding about 200 c. c., which have been thoroughly steril- 
ized, with stoppers in place, in a hot air oven at 200° F., 
must be used for collection. They should be rinsed on 
the outside with water, dipped below the surface, the 
stopper withdrawn, and again inserted when the bottle is 
full. If these are to be transported any distance they 
should be packed in ice. For delivering the measured 
volume of water, a pipette sterilized in the hot-air oven 
should be used. 
Culture Manipulations.—For the estimation and 
isolation of microbes in water, several methods may be em- 
ployed, either the original plate-culture of Koch, Es- 
march’s “ roll-culture,” or a modification that Dr. Beam 
and I have used, which may be designated “ bottle cul- 
ture.” 
Plate-culture.—Test-tubes containing about io c. c. of 
nutrient jelly are plugged with cotton and steamed for 
fifteen minutes in the sterilizer on two successive days. In 
filling the tubes, care must be taken that none of the jelly 
touches the upper part, where it can come in contact with 68 
ANALYTIC OPERATIONS. 
the cotton plug. After sterilization, the tubes should be 
put aside for a few days, to determine if all spores are 
destroyed. If no development of microbes takes place 
in this time, the jelly is ready for use. It should be melted 
at a low temperature in a water-bath, the cotton plug re- 
moved with a twisting motion and a measured volume of 
water introduced by means of a sterilized pipette. The 
plug is immediately replaced and the liquids mixed by 
shaking, taking care not to soil the cotton. The quantity 
of water to be added will depend on the number of 
microbes supposed to be present. If the amount is pro- 
bably quite small, one c. c. should be taken ; if it is 
probable that a large number is present, one c. c. of the 
sample should be diluted to 10 c. c. with sterilized water, 
and one c. c. of this mixture used. In most cases it will 
be well to make several cultures, using different proportions 
of water. After the jelly and water have been mixed the 
liquid is poured out on a glass plate and allowed to set. 
The principal difficulty in the method arises from the 
liability to contamination from the air during this part of 
the process. The glass plates should, of course, be 
thoroughly sterilized. They are usually set upon glass 
benches, and placed in a so-called moist chamber, which 
consists of two cylindrical glass dishes, one fitting within 
the other. The benches and plates are placed in the inner 
dish. To hasten the setting of the jelly, it is necessary 
that the plates should be cold, and it will be best to have 
them resting in a level position on a flat tin bottle filled 
with ice water, or, if ice is not at hand, a recently prepared 
mixture of one part of ammonium nitrate with two parts of 
water. The coated plates must be protected from dust 
while being cooled, and as soon as possible must be trans- SANITARY EXAMINATIONS. 
69 
ferred to the moist chamber, which, as well as the benches, 
should have been previously thoroughly washed with 
recently boiled water. The bottom should be covered 
with a sheet of moist filter-paper. The plates are kept in 
the chamber for several days. Each living microbe that is 
capable of growing in the medium will become the center 
of a colony of its own kind, which will soon become visible 
to the naked eye. The number of colonies may be 
counted as soon as they are distinct. When the number 
is very large, an approximate counting may be made by 
means of a glass plate with lines ruled so as to divide it 
into a considerable number of equal squares. This is 
placed over the culture, and the number of colonies in 
several of the squares counted, the result averaged and 
multiplied by the number of squares that the entire culture 
covers. 
Roll Culture.—Instead of pouring the jelly on a plate, 
it may be spread in a uniform layer on the inner wall of the 
test-tube, taking care not to allow it to touch the cotton. 
The jelly may be rapidly hardened by rolling the tube in 
contact with ice. The method avoids all danger of con- 
tamination with dust, and is very simple in manipulation, 
but is open to the objection that when bacilli are present 
which liquefy the gelatin, as will generally be the case, the 
fluid will run down and inoculate other portions of the layer. 
Bottle Culture.—To avoid the disadvantage of the above 
methods, it will be found convenient to employ flat 
rectangular bottles of the form known technically as the 
“Blake” Bottle. Those of 8 or io ounce capacity are 
the best, and it is well to select such as have as uniform a 
thickness of glass as possible. They should be thoroughly 
cleaned and sufficient of the jelly put in to form a thin ANALYTIC OPERATIONS. 
70 
layer on one of the broader sides when the bottle is placed 
horizontally. The mouth is then closed by a cotton-plug 
and the bottle sterilized as described in connection with 
plate culture. To make a culture, the jelly is melted at a 
low temperature, the measured volume of water added, 
the cotton plug replaced, and after mixing, the bottle is 
placed in a horizontal position for the usual time. 
General Character of the Microbes in Natural 
Waters.—The microorganisms of natural waters are prin- 
cipally included in the genera Bacillus and Spirillum, 
especially the former. Micrococci and moulds are rare, 
and when they appear on the culture-plate, are generally 
due to contamination by dust. 
Microbes are distinguished according to the conditions 
favorable to their growth, as follows: — 
Saprophytic. Growing on dead matter. 
Parasitic. Growing only on living matter. 
Aerobic. Requiring free oxygen. 
Anaerobic. Not requiring free oxygen. 
When the organism possesses the power of adapting itself 
to different conditions, the term facultative is applied ; 
when it can grow only under special conditions, the term 
obligatory is applied. 
Microbes are also differentiated by the effect which they 
produce upon the culture-medium. Some species rapidly 
or slowly liquefy the jelly with evolution of foul smelling 
gases; others—chromogenic microbes—produce character- 
istic colors. Many do not produce any positive modifica- 
tion, and for purposes of distinction it is usual to transfer 
portions of the colonies to other culture-media. Such 
special cultures are obtained by taking up a portion of 
the colony on the end of a wire which has been just SANITARY EXAMINATIONS. 
sterilized by heating to redness and inoculating the pre- 
pared medium. . 
Cultivation in Absence of Oxygen.—Several of the most 
frequently occurring microbes are obligatory anaerobes, 
and will grow, therefore, only in an atmosphere deprived 
of free oxygen. Carbon dioxid has been found to act 
unfavorably upon their development. The most suitable 
atmosphere is one of pure hydrogen. Cultivation in such 
an atmosphere may be secured by constructing the moist 
chamber so as to permit its being filled with hydrogen and 
sealed, or by the use of Liborius’ tube, Fig. 8. 
The tube is charged with nutrient jelly, 
plugged with cotton, sterilized, inoculated 
with the material to be tested, the jelly 
maintained in a liquid condition by a very 
gentle heat and a current of pure hydrogen 
passed through the side tube until all air is 
expelled. The test-tube and side-tube are 
then sealed quickly at the narrow portions, 
in the blow-pipe flame, and the jelly allowed 
to solidify. 
Staining.—The differentiation of the various species of 
microbes may also be accomplished by staining with 
various anilin colors. These methods are, however, more 
generally applicable to pathologic work, that is, to the 
staining of microbes in tissues. 
Indol Reaction.—Indol, C8H7N, more properly indin, is a 
weak base, which is a product of the growth of many species 
of microbes, and the detection of it may, therefore, be util- 
ized as a differentiation test. S. Kitasato (Zeit. f. Hyg., vii, 
518) gives the following method for performing the test:— 
Ten c. c. of an alkaline-peptone-meat infusion (without 
Fig. 8. 72 
ANALYTIC OPERATIONS. 
gelatin), which has been previously inoculated with the 
microbes to be tested, and kept for twenty-four hours at 
blood heat, are treated with one c. c. of solution of pure 
potassium nitrite (0.02 grm. in 100 c. c.) and then with 
a few drops of concentrated sulphuric acid. In the pres- 
ence of indol a rose or deep-red color is developed. Spi- 
rillum cholera and Bacillus coli-communis give the reaction 
strongly; S. Finkleri feebly; the so-called B. typhosus 
does not give it. 
An effort has been made to distinguish dangerous mi- 
crobes by employing crucial conditions of cultivation 
which are believed to eliminate the harmless forms. One 
of the most complete methods is that used in the Hygi- 
enic Laboratory of the University of Michigan, under the 
supervision of Dr. Vaughan : — 
The water is collected in sterilized bottles, and beef-tea 
tubes are inoculated with it, from one drop to one cubic 
centimeter being added to each tube. The inoculated 
tubes are kept at 38° C. for twenty-four hours. 
Many germs found in drinking-water will not grow at 
so high a temperature. It is assumed that a germ which 
will not grow at the temperature of the human body can- 
not possibly induce disease. Of the germs which do grow 
at 38°, or higher, some are toxicogenic to animals, while 
others are not. Whether the germs in a given sample 
are toxicogenic or not, is determined by injecting the pre- 
pared cultures subcutaneously or intra-abdominally in rats, 
guinea-pigs, rabbits, or mice. 
Waters not containing toxicogenic germs growing at 
38° or higher are reported as safe. 
Waters containing toxicogenic germs growing at 38° C. 
are condemned. In testing virulence, a germ is not SANITARY EXAMINATIONS. 
73 
pronounced toxicogenic unless it be found growing and 
multiplying in the animal inoculated with it. 
The Franklands (“Microorganisms in Water”), after 
reviewing at length the various methods that have been 
suggested for differentiating the typhoid-bacillus, show 
that most of them are quite insufficient. A routine treat- 
ment is, however, suggested as follows: — 
The water is freed from the ordinary water-bacteria 
by preliminary culture in Parietti’s solution. This is a 
phenol-broth prepared by mixing 10 c. c. of neutral 
bouillon with 0.25 c. c. of the following solution :— 
Phenol, 5 grams. 
Hydrochloric acid, 4 “ 
Water, 100 “ 
This solution is sterilized by heating it for twenty-four 
hours at 370 C. The tubes are then inoculated with from 
one to ten drops of the water-sample, which must be 
thoroughly mixed with the broth, and again kept in the 
sterilizer for not less than forty-eight hours. If any of 
the tubes appear turbid after the treatment, they should be 
submitted to plate-cultivation, and any colonies which 
resemble those produced by the typhoid-bacillus should be 
further studied by inoculation into gelatine tubes to observe 
the gas producing test, into milk to note if coagulation 
occurs, and by cultivation in broth to determine if indol- 
reaction will be obtained. 
Hazen and White (“ Manual of Bacteriology,” Stern- 
berg, p. 354) cultivate the water in agar-agar tubes at 
40° C. for several days, which prevents the growth of 
many of the common water-microbes. 
Vaughan (“Proceedings American Association of Phy- 
sicians, 1892”) investigated the application of these prin- 74 
ANALYTIC OPERATIONS. 
ciples to the isolation of a specific bacillus, but did not 
obtain satisfactory results. 
From the Franklands’ work I take the description of 
methods used for detection of the Spirillum cholerce in water. 
According to Koch, 100 c. c. of water is mixed with one 
per cent, each of peptone and common salt and the mix- 
ture kept at 370 C. At intervals of ten, fifteen, and twenty 
hours plate-cultivations are made of portions of the sample. 
Any colonies which appear on the plates should be re- 
inoculated into fresh culture-media and be tested after a 
time for indol. 
Schottelius recommends the following: The water is 
mixed with twice its volume of alkaline sterile bouillon, 
and kept at a temperature of 30-40° C. for twelve hours. 
An extensive multiplication of the spirillum occurs on the 
surface of the liquid, and the examination of the pellicle 
will show many of them. 
Klein (Br. Med. Jour., Oct. 14, 1894) has pointed out 
that in most of the methods for isolating pathogenic 
microbes, the volume of water used is too small. He 
suggests the employment of at least 1000 c. c. Obviously 
this volume will give a better sampling than the few drops 
or 1 c. c. generally used. 
TECHNIC EXAMINATIONS. 
GENERAL QUANTITATIVE ANALYSIS. 
Silica, Iron, Aluminum, Manganese, Calcium, 
and Magnesium.—One liter of the water acidified with 
hydrochloric acid is evaporated to complete dryness, best 
in a platinum dish, the residue treated with hydrochloric TECHNIC EXAMINATIONS. 
75 
acid and water, and the separated silica filtered, washed, 
dried, ignited in a platinum crucible, and weighed. 
To the filtrate, previously boiled with a few drops of 
strong nitric acid, slight excess of ammonium hydroxid is 
added, the liquid boiled several minutes, the precipitate 
collected, washed thoroughly with boiling water, dried, 
ignited, and weighed. It consists of Fe203 and A/203. It 
also contains all the phosphates and some manganese if 
much is present in the water. In such cases the precipitate 
before drying is re-dissolved in hydrochloric acid and 
neutralized with a dilute solution of ammonium carbonate 
until the water almost becomes turbid. It is then boiled 
and the precipitate, now free from manganese, washed, 
dried, ignited, and weighed. The iron may be determined 
by dissolving the precipitate in strong hydrochloric acid 
and employing the colorimetric method described on page 
38- 
If no manganese or only traces are present, the filtrate 
from the iron is mixed with sufficient ammonium chlorid 
to prevent the precipitation of the magnesium, ammonium 
hydroxid, and then ammonium oxalate added in quantity 
sufficient to precipitate the calcium and to convert all the 
magnesium into oxalate, and thus hold it in solution. The 
precipitate contains all the calcium and some of the mag- 
nesium. If the magnesium is present only in relatively 
smallquantity the amount carried down may be disregarded; 
otherwise a second precipitation should be made as follows : 
The solution is allowed to stand until the precipitate has 
subsided ; this will require some hours. The supernatant 
liquid is poured off through a filter, the precipitate washed 
by decantation, then dissolved in hydrochloric acid, water 
added, then ammonium hydroxid and a small quantity 76 
ANALYTIC OPERATIONS. 
of ammonium oxalate. After the calcium oxalate has 
thoroughly subsided it is filtered off, washed, and dried. If 
quite small in amount it is placed with the filter in a weighed 
platinum crucible, ignited over the Bunsen burner for a 
short time, and then over the blast lamp for from five to 
fifteen minutes. The calcium is thus obtained in the form 
of oxid, which is allowed to cool in the desiccator and 
weighed. The weight thus obtained multiplied by 0.714 
gives the weight of calcium. When the amount of precipi- 
tate is large, it is better to remove it from the filter, and 
heat it just short of redness until it assumes a grayish tint. 
It then consists of calcium carbonate. To this is added 
the ash of the filter. The weight of the calcium carbonate 
multiplied by 0.4 gives the weight of calcium. 
The filtrates are mixed, slightly acidified with hydro- 
chloric acid, concentrated and cooled, ammonium hydroxid 
and sodium phosphate added in excess, stirred briskly 
and allowed to stand in the cold for about twelve hours. 
The precipitated ammonium magnesium phosphate is 
brought upon a filter, that adhering to the sides of the ves- 
sel being dislodged by rubbing with a glass rod tipped with 
a piece of clean rubber tubing. It is washed with a solu- 
tion made by mixing one part of the ammonium hydroxid 
of 0.96 sp. gr. with three parts of water. The precipitate 
is dried, transferred to a platinum crucible, the filter ashed 
separately and added to it, and the whole heated at first 
gently and then to intense redness for several minutes. 
After cooling, it is weighed. It consists of magnesium 
pyrophosphate; the weight multiplied by 0.218 gives the 
weight of magnesiutn. 
Manganese, if present in appreciable quantity, is sepa- 
rated before the precipitation of the calcium, as follows : TECHNIC EXAMINATIONS. 
The filtrate from the iron precipitate is slightly acidulated 
with hydrochloric acid, concentrated, and the manganese 
precipitated as sulphid by colorless or slightly yellow solu- 
tion of ammonium sulphid. The flask, which 'should be 
nearly full, is stoppered, allowed to rest in a moderately 
warm place until the precipitate has thoroughly settled, 
filtered, washed with dilute ammonium sulphid water and 
purified by dissolving in a small quantity of hydrochloric 
acid and reprecipitating with ammonium sulphid. It is 
filtered off, washed as before, dried, placed in a weighed 
porcelain crucible, covered with a little sulphur and ignited 
in a current of hydrogen introduced into the crucible by a 
tube passing through a hole in the cover. The pure man- 
ganese sulphid thus obtained is allowed to cool and 
weighed. The weight multiplied by .632 gives man- 
ganese. 
Sulphates.—500 c. c. of the clear water are slightly 
acidulated with hydrochloric acid, heated to boiling, and 
barium chlorid solution added in moderate success. The 
precipitate is allowed to subside completely, collected upon 
a filter, washed thoroughly, dried and incinerated. It is 
BaS04; the weight multiplied by 0.412 gives S04. If the 
proportion of S04 is very low, it will be advisable to con- 
centrate the water to one-fifth or one-tenth its bulk before 
precipitating. 
Control. Potassium, Sodium, and Lithium.— 
From 250 to 1000 c. c. of the water, according to the 
amount of solid matters present, are evaporated to dryness 
in a platinum dish, and the residue treated with a small 
amount of water and sufficient dilute sulphuric acid to 
decompose the salts present. The dish should then be 
covered and placed upon the water-bath for five or ten 78 
ANALYTIC OPERATIONS. 
minutes, after which any liquid spurted on the cover is 
washed into the dish, the whole evaporated to dryness 
and heated to redness. A few drops of ammonium 
carbonate solution should then be mixed with the resi- 
due, and the ignition repeated to insure the removal of 
the last portions of free acid. In the majority of cases 
the only basic elements present in considerable quantity 
are calcium, magnesium, and sodium. The sodium may be 
determined indirectly, therefore, by calculating from the 
amount of Ca and Mg found, the calcium and magne- 
sium sulphate in the residue, and subtracting this sum, 
together with the silica, from the total residue. 
For the determination of potassium and sodium in ordin- 
ary well and river waters, not less than two liters should be 
employed. When lithium is to be determined, it is gener- 
ally necessary to use much more. In any case, as the alkalies 
are to be weighed as chlorids, it is advisable, if notable 
amounts of sulphates are present, to precipitate them by 
addition of barium chlorid. 
The water is evaporated to about 200 c. c., a slight 
excess of calcium hydroxid added to the hot liquid—gen- 
erally 3 c. c. of thin milk of lime will be sufficient—and the 
heat continued for several minutes. It is then washed into 
a 250 c. c. flask, disregarding the insoluble portion ad- 
hering to the dish, which, however, should be thoroughly 
washed, and the washings added to the flask. After cool- 
ing, the flask is filled up to the mark with distilled water, 
thoroughly mixed, the precipitate allowed to settle, and 
the liquid filtered through a dry filter. 200 c. c. of the 
filtrate are measured into another 250 c. c. flask, 
ammonium carbonate and ammonium oxalate added, 
filled with water up to the mark, mixed, allowed to settle, TECHNIC EXAMINATIONS. 
79 
filtered through a dry filter, 200 c. c. of the filtrate 
measured off and evaporated to thorough dryness in a 
platinum crucible, heating very cautiously at the last stages 
to avoid loss by spurting. The low-temperature burner is 
suited for this purpose. The crucible is now covered and 
cautiously heated to dull redness, cooled and weighed. 
The residue contains the potassium, lithium and sodium 
as chlorids. It contains, sometimes, also, traces of mag- 
nesium, which may be removed by treating again with 
lime and ammonium carbonate and oxalate. It is fre- 
quently of advantage, in evaporating these saline solutions, 
to add, when the solution becomes concentrated, several 
c. c. of strong hydrochloric acid. This precipitates the 
greater portion of the salts in a finely granular condition, 
and renders loss by spurting less liable to occur. 
If potassium and sodium chlorids only are present, the 
residue is dissolved in a small quantity of water, an 
excess of a concentrated neutral solution of platinum 
chlorid added, evaporated to small bulk at a low heat 
on the water bath, some 80 per cent, alcohol added, 
allowed to stand, the clear liquid decanted off on a 
small filter and the residue washed in this way several 
times by fresh small portions of 80 per cent, alcohol. The 
precipitate is then washed on to the filter with alcohol, 
washed again with 80 per cent, alcohol, thoroughly dried 
and transferred as far as possible to a watch glass. The 
small portion on the filter is dissolved off and the solution 
placed in a weighed platinum dish and evaporated to dry- 
ness. The main portion on the watch glass is then added, 
and the whole dried to a constant weight at about 260° F., 
cooled and weighed. The weight thus found multiplied 
by .30 gives the weight of potassium chlorid. This sub- 80 
ANALYTIC OPERATIONS. 
tracted from the combined weight of the chlorids gives 
the weight of sodium chlorid. 
Lithium, if present, is best separated before the treatment 
with platinum chlorid. The following method, devised 
by Gooch, gives good results: To the concentrated solu- 
tion of the weighed chlorids, amyl alcohol is added and 
heat applied, gently at first, to avoid bumping, until the 
water disappears from the solution and the point of ebulli- 
tion becomes constant at a temperature which is approxi- 
mately that at which the alcohol boils (270° F.), the 
potassium and sodium chlorids are deposited and the 
lithium chlorid is dehydrated and taken into solution. 
The liquid is then cooled and a drop or two of strong 
hydrochloric acid added to reconvert traces of lithium hy- 
droxid in the deposit, and the boiling continued until the 
alcohol is again free from water. If the amount of lithium 
chlorid be small, it will be found in the solution and the 
potassium chlorid and sodium chlorid in the residue, 
excepting traces which can be allowed for. If the lithium 
chlorid exceed ten or twenty milligrams the liquid may be 
decanted, the residue washed with amyl alcohol, dissolved 
in a few drops of water and treated as before. For wash- 
ing, amyl alcohol, previously dehydrated by boiling, is to 
be used and the filtrates are to be measured apart from the 
washings. In filtering, the Gooch filter with asbestos felt 
may be used with advantage, applying gentle pressure by 
the aid of the filter pump. The crucible and residue are 
ready for weighing after gentle heating over the low-tem- 
perature burner. The weight of the insoluble chlorids is 
to be corrected by adding .00041 for every 10 c. c. of amyl 
alcohol in the filtrate, exclusive of the washings, if only 
sodium chlorid be present; .00051 for every 10 c. c. if TECHNIC EXAMINATIONS. 
81 
only potassium chlorid, and .00092 in the presence of 
both these chlorids. 
The filtrate and washings are evaporated to dryness in a 
platinum crucible heated with sulphuric acid, the excess 
driven off, and the residue ignited to fusion, cooled and 
weighed. From the weight is to be subtracted, for each 
10 c. c. of filtrate, .0005, .00059, or .00109, according as 
only sodium chlorid, potassium chlorid, or both were 
present in the original mixture. 
Hydrogen Sulphid.—The following method is taken 
from Sutton’s “Volumetric Analysis:”— 
Reagents Required: — 
Centinormal Iodin.—Dry, commercial iodin is inti- 
mately mixed with one-fourth its weight of pure potassium 
iodid and gently heated between two clock-glasses by 
resting the lower on a hot plate. The iodin sublimes in a 
perfectly pure condition. It is allowed to cool under the 
desiccator, 1.265 grams weighed out, together with 1.8 
grams of pure potassium iodid, dissolved in about 50 c. c. 
of water and the solution made up exactly to a liter. The 
liquid must not be heated, and care should be taken that 
no iodin vapor is lost. One c. c. is equivalent to .00017 
H3S. The solution is best prepared in stoppered bottles, 
which should be completely filled and kept in the dark. 
It will not even then keep very long, and should be stand- 
ardized by titration with a weighed amount of pure so- 
dium thiosulphate, which should be powdered previous to 
weighing, and pressed between filter paper to absorb any 
moisture. 50 c. c. of the iodin solution, when of full 
strength, will require 0.124 gram of sodium thiosulphate. 
Starch Indicator.—See page 48. 82 
ANALYTIC OPERATIONS. 
Analytic Process:— 
Ten c. c., or any other necessary volume of the iodin 
solution, is measured into a 500 c. c. flask, and the water 
to be examined added until the color disappears. Five 
c. c. of starch liquor are then added and the iodin solution 
run in until the blue copper appears; the flask is then filled 
to the mark with distilled water. The respective volumes 
of iodin and starch solution, together with the added 
water, deducted from the 500 c. c. will show the volume 
of water actually titrated by iodin. A correction should 
be made as follows for the excess of iodin required to pro- 
duce the blue color : Five c. c. starch solution are made 
up with distilled water to 500 c. c., iodin run in until the 
color matches that in the test, and the volume of iodin 
solution so used subtracted from the figure obtained in the 
first titration. 
Hardness. C03 in Normal Carbonates.—Waters 
containing considerable quantities of calcium and magne- 
sium are said to be hard. Since the solution of calcium 
and magnesium carbonate in water depends partly upon 
the presence of carbon dioxid, boiling precipitates the 
greater portion of the carbonates, the result being to di- 
minish the hardness, i. e., to soften the water. Magne- 
sium and calcium sulphates and chlorids are not precipi- 
tated in this way. Hardness, therefore, is divided into 
two classes, temporary and permanent, the former being 
that which may be removed by boiling. The process here 
described is due to Hehner. 
Reagents Required:— 
Standard Sodium Carbonate. —1.06 grams of recently 
ignited pure sodium carbonate are dissolved in water and TECHNIC EXAMINATIONS. 
the solution diluted to 1000 c. c. One c. c. = .00x06 gram 
Na2C03, equivalent to .001 gram CaC03. 
Standard Sulphuric Acid.—One c. c. of pure concen- 
trated sulphuric-acid is added to about 1000 c. c. of water. 
50 c. c. of the standard sodium carbonate are placed in a 
porcelain dish, heated to boiling, a few drops of a solution 
of phenacetolin or lacmoid added, and the sulphuric acid 
cautiously run in from a burette until the proper change of 
color occurs. From the figure thus obtained, the extent 
to which the acid should be diluted in order to make one 
c. c. of the sodium carbonate equivalent to one c. c. of 
the acid may be calculated. The proper amount of water 
is then added and the solution verified by again titrating. 
Analytic Process :— 
Temporary Hardness.—xooc. c. to 250 c. c. of the water 
tinted with the indicator are heated to boiling, and the 
sulphuric acid cautiously run in until the color change 
occurs. Each c. c. required will represent one part of cal- 
cium carbonate or its equivalent per 100,000 parts of the 
water. 
Permanent Hardness.—To ioo c. c. of the water is 
added an amount of the sodium carbonate solution more 
than sufficient to decompose the calcium and magnesium 
sulphates, chlorids and nitrates present; usually a bulk 
equal to the water taken will be more than sufficient. The 
mixture is evaporated to dryness in a nickel or platinum 
dish, and the residue extracted with distilled water. The 
solution is filtered through a very small filter, and the filtrate 
and washings titrated hot with sulphuric acid as above; or 
25 c. c. of distilled water may be poured on the residue, 
and the solution obtained filtered through a dry filter, the 
filtrate measured and titrated. The difference between 84 
ANALYTIC OPERATIONS. 
the number of c. c. of sodium carbonate used and the acid 
required for the residue will give the permanent hardness. 
If the water contains sodium or potassium carbonate 
there will be no permanent hardness, and there will be 
more acid required for the filtrate than the equivalent of 
the sodium carbonate added. From this excess the 
quantity of sodium carbonate in the water may be deter- 
mined. 
Since any alkali-carbonate in the water would be erro- 
neously calculated as temporary hardness by the direct 
titration, the equivalent, in terms of calcium carbonate, of 
the alkali carbonate present should be deducted from the 
figure given by the titration in order to get the true tem- 
porary hardness. 
The total C03 in normal carbonates is given by the 
direct titration of the water with dilute sulphuric acid. 
One c. c. of the acid is equivalent to .0006 gram of C03. 
Free Carbonic Acid.—The following process, due to 
Pettenkofer, is taken from Sutton’s “ Volumetric Analy- 
sis — 
A stoppered bottle of known capacity, about 150 c. c., 
is filled at the source by submergence, or, if taken from a 
faucet, by allowing the stream to run in with full force for 
some minutes, the nozzle being inserted into the neck of 
the bottle. 50 c. c. of the water are then quickly removed 
by a pipette, and the following solutions immediately 
added: Three c. c. of a saturated solution of calcium 
chlorid and two c. c. of a saturated solution of ammonium 
chlorid; 45 c. c. of clear calcium hydroxid solution of 
known strength are added, the flask well corked, the liquids 
mixed, and set aside for at least twelve hours, to allow the 
calcium carbonate formed to settle and become crystalline TECHNIC EXAMINATIONS. 
85 
and insoluble. An aliquot part (50 to 100 c. c.) of the 
clear liquid is then drawn olf and titrated with decinormal 
acid, using phenacetolin or lacmoid as indicator, and from 
the amount required the entire proportion of calcium hy- 
droxid unacted upon can be determined. This being 
deducted from the amount originally added, and the 
remainder multiplied by .0022, will give the weight of 
carbonic acid in the water in excess of that existing as 
normal carbonates. 
Boric Acid.—Detection.—Add to one liter of the 
water sufficient sodium carbonate to render it distinctly 
alkaline. Evaporate to dryness, acidify with hydrochloric 
acid, moisten a slip of turmeric paper with the liquid, and 
dry it at a moderate heat. In the presence of boric acid 
the paper will assume a distinct brown-red tint. 
Quantitive determinations of boric acid are rarely re- 
quired. It exists in many of the geyser-waters of Yellow- 
stone National Park, and doubtless in similar waters in 
other parts of the world. A careful investigation into the 
methods of quantitive determination was published by 
Hehner (The Analyst, August, 1891) and a modification of 
Gooch’s method is described by Moissan (Jour. Soc. 
Chem. Ind., April 1, 1895). 
SPECTROSCOPIC EXAMINATION 
For the ordinary spectroscopic examination of a water 
a simple apparatus will suffice. The arrangement figured 
in the cut (Fig. 9) is a small direct-vision spectroscope, 
held in a universal stand, with an adjustable burner as the 
source of heat. The entire apparatus does not cost over 
$15,00, and will be found convenient and efficient. 
For the examination, a liter or more should be evapo- 86 
ANALYTIC OPERATIONS. 
rated nearly to dryness, a little hydrochloric acid being 
added near the end of the 
process, the residue placed 
in a narrow strip of plati- 
num foil having the sides 
bent so as to retain the 
liquid, and heated in the 
flame. While this method 
will be sufficient in many 
cases, a far better plan is 
to separate the substance 
sought for in a state of ap- 
proximate purity and then 
examine with the spectro- 
scope. Very small traces 
of lithium, for instance, 
may be detected as follows: 
To about a liter of the 
water sufficient sodium 
carbonate is added to pre- 
cipitate all the calcium and 
magnesium, and the liquid 
boiled down to about one- 
tenth its bulk ; it is then filtered, the filtrate rendered 
slightly acid with hydrochloric acid and evaporated to dry- 
ness. The residue is boiled with a little alcohol, which 
will dissolve out the lithium chlorid. The alcoholic 
solution is evaporated to dryness, the residue taken up 
with a little water and tested in the flame. 
Fig. 9. 
In order to identify with certainty any line which may 
be obtained, it is only necessary to hold in the flame at 
the same time a wire which has been dipped in a solution TECHNIC EXAMINATIONS. 
87 
of the substance supposed to be present, and to note 
whether the lines produced by it and the material under 
examination are identical. 
SPECIFIC GRAVITY. 
In the great majority of cases the determination of 
specific gravity is not essential. Ordinary river, spring and 
well waters contain such small proportions of solid matter 
that it is usually the practice to take a measured volume 
and to assume its weight to be that of an equal bulk of 
pure water. If the proportion of solids be high, a deter- 
mination of the specific gravity may be desirable. For 
this purpose the specific gravity bottle may be used. This 
consists merely of a small flask provided with a finely per- 
forated glass stopper. The bottle is weighed first alone, 
then filled with distilled water at 6o° F., and finally with 
the water under examination at the same temperature. In 
filling the bottle, the liquid is first brought to the proper 
temperature, the bottle completely filled, the stopper in- 
serted, and the excess of water forced out through the 
perforation and around the sides of the stopper, carefully 
removed by bibulous paper. The weight of the water 
examined divided by the weight of the equal bulk of dis- 
tilled water at the same temperature gives the specific 
gravity. 
Another method, and one which gives very satisfactory 
results, is by the use of a plummet. This may conveniently 
consist of a piece of a thick glass rod of about io c. c. in 
bulk, or of a test-tube weighted with mercury and the open 
end sealed in the flame. The plummet is suspended to the 
hook of the balance by means of a fine platinum wire and 
its weight ascertained. It is then immersed in distilled 88 
ANALYTIC OPERATIONS. 
water at 6o° F., and the loss in weight noted. The figure 
so obtained is the weight of a bulk of water equal to that 
of the plummet. This having been determined, the specific 
gravity of any water may be found by immersing in it the 
plummet and noting the loss in weight. This, divided by 
the loss suffered in pure water, gives the specific gravity. INTERPRETATION OF RESULTS. 
STATEMENT OF ANALYSIS. 
The composition of water is generally expressed in terms 
of a unit of weight in a definite volume of liquid, but much 
difference exists as to the standard used. The decimal 
system is very largely employed, the proportions being 
expressed in milligrams per liter, nominally parts per mil- 
lion ; or in centigrams per liter, nominally parts per hun- 
dred thousand. Not infrequently the figures are given in 
grains per imperial gallon of 70,000 grains, or the U. S. 
gallon of 58,328 grains. Much more rarely grains per 
quart, parts per thousand, per cent., or other inconvenient 
ratios are employed. In this work the composition is 
always expressed in milligrams per liter. This ratio is 
practically equivalent to parts per million, except in case 
of water very rich in solids, a liter of which weighs nota- 
bly more than one million milligrams. Factors for con- 
verting the different ratios are given at the end of the 
book. 
From the analysis of a water it is rarely possible to ascer- 
tain the exact arrangement of the elements determined, but 
it is the custom to assume arrangements based upon the 
rule of associating in combination elements having the 
highest affinities, modifying this system by any inferences 
derived from the character or reactions of the water itself. 
It has been demonstrated that, even in the case of mixtures 90 
INTERPRETATION OF RESULTS. 
of salts producing no insoluble substances, partial inter- 
change of the basylous and acidulous radicles takes place. 
In a solution of sodium chlorid and potassium sulphate 
sodium sulphate and potassium chlorid will be found, as 
well as the original salts. When the conditions are ren- 
dered more complex by the addition of other substances, 
it is obviously impossible to determine the exact arrange- 
ment. In view of these facts, it is preferable to express 
the composition of a water by the proportion of each ele- 
ment or radicle present. In this way a water containing 
K2S04, will be expressed in terms of K and S04, respec- 
tively. In the case of bodies like C02 and Si02, which may 
possibly exist free -in the water, their proportion is expressed 
as such. It frequently occurs that the characteristics of 
some of the compounds in a water are sufficiently marked 
to indicate their presence, and there can be no objection 
to suggesting, in connection with the analytic statement, 
the inferences which may thus be drawn. 
The organic matters, or derived products, are best 
stated in terms of the nitrogen which they contain, thus 
permitting a comparison of the different stages of decom- 
position. It is inadvisable to represent the amount of 
unchanged organic matter in terms of oxalic acid, as has 
been suggested, or to express the nitrogen in terms of albu- 
min, or any other supposititious compound. 
SANITARY APPLICATIONS. 
Judgment upon the analytic results from a given sam- 
ple of water depends upon the class to which it belongs, 
and to the particular influences to which it has been sub- 
jected. A proportion of total solids which would be sus- 
picious in a rain or river water, would be without signifi- SANITARY APPLICATIONS. 
cance in that from an artesian well. On the other hand, a 
subsoil water of unobjectionable character would contain a 
proportion of nitrates which would be inadmissible in the 
case of a river or deep water. Location has also much 
bearing in the case; subsoil waters near the sea will be 
found to contain, without invoking suspicion, proportions 
of chlorin which would be ample to condemn the same 
sample if derived from a point far inland. Hence the im- 
portance of recording, at the time of collection, all ascer- 
tainable information as to the surroundings and probable 
source of the water. 
91 
Analyses of surface-waters have little value, unless supple- 
mented by a careful survey of the watershed to determine 
sources of pollution. Such survey will often discover 
conditions sufficient to condemn the supply, even though 
the analyses may be satisfactory. Indeed, it may be taken 
as a fundamental principle, that no water-supply derived 
from streams flowing through a populated district will be 
safe for use unless efficiently filtered. 
Color, Odor, and Taste.—Water of the highest 
purity will be clear, colorless, odorless, and nearly tasteless. 
While in some cases a decided departure from this stand- 
ard may give rise to suspicion, analytic observations are 
necessary to decide the point. Water highly charged 
with mineral matters will possess decided taste, vegetable 
matters may communicate distinct color; but, on the 
other hand, it may be highly contaminated with dangerous 
substances and give no indications to the senses. Well- 
waters occasionally become offensive in odor, from pene- 
tration of tree roots. The odor often recalls that of 
hydrogen sulphid. Sulphids are, indeed, often formed in 
such cases by the abstraction of oxygen from sulphates 92 
INTERPRETATION OF RESULTS. 
under the influence of microbes. Such waters are often 
used without apparent injury, but it is probable that if 
direct pollution occurs, the danger would be enhanced by 
the presence of the vegetable matter. Miquel has de- 
scribed a bacillus, under the name B. sulphydrogenus, 
which produces hydrogen sulphid readily. Some of the 
common putrefactive bacilli doubtless have this* power 
also, largely through the influence of the hydrogen lib- 
erated by them. In waters containing hydrogen sulphid, 
species of beggiatoa, especially B. alba, thrive, and 
decomposing the sulphid, become impregnated with sul- 
phur. Natural sulphur waters frequently contain these 
organisms, as do, also, waste-waters containing sulphid. 
Surface waters collected in reservoirs or ponds often 
become very offensive from the growth of algae, but apart 
from the disgust created by the water it is not known that 
any harmful results occur to those using it. 
Turbidity may be due to several causes, of different 
degrees of danger, but is always objectionable. 
Total Solids.—Excessive proportions of mineral 
solids, especially of marked physiological action, are 
known to render water non-potable, but no absolute max- 
imum or minimum can be assigned as the limit of safety. 
Distilled water and waters very highly charged with min- 
eral matter have been used for long periods without ill 
effects. The popular notion that the so-called hard waters 
conduce to the formation of urinary calculi is not borne 
out by surgical experience nor statistical inquiry. Many 
urinary calculi are composed of uric acid, and are the 
results of disorders of the general nutritive functions. 
Sanitary authorities have fixed an arbitrary limit of total 
solids of about six hundred parts per million, but many SANITARY APPLICATIONS. 
93 
artesian waters in constant use exceed this. An instance 
is found in the well on Black’s Island, near Philadelphia, 
given in the table of analyses, which contains nearly 
twelve hundred parts per million, is very agreeable in 
taste, and has been in constant use for some years by a 
number of persons without injury. The assertion that water 
to be wholesome must contain an appreciable proportion 
of total solids is also not demonstrated by clinical expe- 
rience. A discussion of the effects of special mineral 
ingredients, e. g., magnesium sulphate, ferrous carbonate, 
etc., belongs to general therapeutics. 
The odor produced on heating the water residue is often 
of much use in detecting contamination. Odors similar 
to those produced by heating glue, hair, rancid fats, urine, 
or other animal products, will give rise to grave suspicion. 
On the other hand, a more favorable judgment may be 
given when the odor recalls those given off in the heating 
of non-nitrogenous vegetable materials, such as wood-fibre. 
Poisonous Metals.—The proportion of iron in water 
constantly used for drinking purposes should not much 
exceed three parts per million. Lead, copper, arsenum, 
and zinc must be considered dangerous in any amount, 
though it appears that zinc and copper, being least cumu- 
lative, are rather less objectionable in minute amount than 
the others. Concerning the limit of safety with mangan- 
ese and chromium very little is known, but their presence 
in appreciable quantity must be looked upon with suspicion. 
Chlorids and Phosphates.—Chlorids—principally 
sodium chlorid—and phosphates are abundantly distrib- 
uted in rocks and soils, and find their way into natural 
waters; but while the former are freely soluble, and remain 
in undiminished amount under all conditions to which the 94 
INTERPRETATION OF RESULTS. 
water is subjected, all but minute amounts of the latter 
are either precipitated or removed by the action of living 
organisms. Surface and subsoil waters ordinarily contain 
but a few parts per million. Both chlorids and phos- 
phates being constant and characteristic ingredients of 
animal excretions, it is obvious that an excess of them in 
natural waters, unless otherwise accounted for, will suggest 
direct contamination. Proximity to localities in which 
sodium chlorid is abundant, such as the sea or salt de- 
posits, will deprive the figure for the chlorin of diagnostic 
value, nor can any indication of sewage or other danger- 
ous pollution be inferred from high proportion of chlorin 
in deep waters. Further, it has been shown that the pro- 
portion of chlorin in uncontaminated waters is tolerably 
constant, while in water subjected to the infiltration of 
sewage the chlorin undergoes marked variation in amount. 
In most cases, therefore, a correct judgment can only be 
attained by comparison with the average character of the 
waters of the same type in the district, and by examination 
at intervals of the water in question. 
As regards phosphates, Hehner, who has published a 
series of analyses, states that the presence of more than 0.6 
parts per million—calculated as P04—should be regarded 
with suspicion. On the other hand, the absence of phos- 
phates affords no positive proof of the freedom from pollu- 
tion. 
Nitrogen from Ammonium Compounds.—Ammo- 
nium compounds are usually the results of the putrefactive 
fermentation of nitrogenous organic matter; they may also 
be the product of the reduction of nitrites and nitrates 
in presence of excess of organic matter. In either case, 
therefore, they suggest contamination. Deep waters often SANITARY APPLICATIONS. 
95 
contain an excess of ammonium compounds, derived, in 
large part, from the reduction of nitrates. Their presence 
here is hardly ground for adverse judgment, since the 
water, even though originally contaminated, has undergone 
extensive filtration and oxidation, its organic matter con- 
verted into bodies presumably harmless, and microbes have 
perished. Such waters, indeed, usually show only traces 
of unchanged organic matter. 
Rain water often contains large proportions of ammo- 
nium compounds; but here, also, the fact cannot condemn 
the water, since it does not indicate contamination with 
dangerous organic matter. 
The evolution of ammonia in the distillation of rain water 
often continues indefinitely, the larger portion passing over 
in the first distillates, but small quantities being present 
even after the distillation has been much prolonged. The 
same continuous evolution of ammonia is noted in waters 
containing urea, but in this case a larger proportion is 
collected in the earlier distillates, nearly all coming over 
before one-half the water has been distilled. Fox gives the 
following figures as ratios obtained in the analysis of two 
samples, one of rain water collected from a roof and there- 
fore impure, and the other of a water containing urine:— 
Rain Water. 
1st distillate, 35 
2d “ .... .25 
3d “ 12 
4th “ 09 
5th “ 09 
6th “ .... ‘04 
7 th “ 03 
•97 
Urine Water. 
.38 parts per million. 
.14 
.065 
.035 
<< <t 
U i( 
(( u 
.620 INTERPRETATION OF RESULTS. 
96 
Nitrogen by Alkaline Permanganate (Nitrogen of 
“albuminoid ammonia ”).—A large yield of ammonia by 
boiling with alkaline potassium permanganate will, of 
course, point to an excess of nitrogenous organic matter. 
The inferences to be drawn depend upon the origin and 
condition of the organic material. If animal, the water 
may at once be condemned as unsafe. Waters containing 
excessive amounts even of vegetable matter are not free 
from objection, since they have frequently caused persistent 
diarrhea. If the organic matter, whether animal or 
vegetable, is in a state of active decomposition, it is 
doubly objectionable. Mallet has called attention to the 
fact that such waters, as a rule, yield ammonia rapidly, 
whereas non-decomposing material yields it but slowly, and 
he points out the importance, therefore, of noting the rate 
at which the ammonia collects in the distillate. 
Dr. Smart has observed that water containing fermenting 
vegetable matter is colored yellow by boiling with sodium 
carbonate, and that when Nessler reagent is added to the 
distillate, a greenish, in place of the ordinary yellowish- 
brown color is produced. He applies this fact in con- 
junction with the determination of the oxygen-consuming 
power (Tidy’s process) and the rate of evolution of the 
ammonia by alkaline permanganate as follows :— 
A water yielding ammonia slowly by alkaline perman- 
ganate, contains recent organic matter ; of animal deriva- 
tion, if the oxygen-consuming power is low; of vegetable, 
if high. 
A water yielding ammonia more rapidly by alkaline 
permanganate, shows decomposing organic matter; of 
animal origin, if the oxygen-consuming power be low and 
there be no interference with the Nessler reaction; of SANITARY APPLICATIONS. 
97 
vegetable origin, if the oxygen consumed be high, and if 
a yellow color be produced in the water by sodium car- 
bonate, and a greenish color in the nesslerized distillate. 
Inferences as to the source of the organic matter can 
usually be drawn from the amount of chlorin and nitrates 
present. If the chlorin be high, i. <?., in excess of the 
average of the district, it may be inferred that the material 
is, in great part, of animal origin. In this case the 
nitrates will either be high or entirely absent, according as 
the contaminating matter has passed through soil or enters 
the water directly. 
A large amount of vegetable matter will, as a rule, show 
itself by the color it imparts to the water. 
Wanklyn gives the following standards :— 
High purity, 00 to .041 per million. 
Satisfactory purity, 041 to .082 “ “ 
Impure, over .082. 
In the absence of ammonium compounds, he does not 
condemn a water unless the nitrogen by permanganate ex- 
ceeds .081 per million; but a water yielding o. 123 parts 
per million of nitrogen by permanganate he condemns 
under all circumstances. 
Total Nitrogen.—Drown and Martin’s results with 
surface waters indicate that the total nitrogen obtained by 
their process is about twice that obtained by alkaline per- 
manganate. The experiments made by Dr. Beam and my- 
self accord with this. Further observation on different 
waters and by different observers will be required to de- 
termine the value to be assigned to the figures obtained 
by this method. This method is especially suitable for 
studying the effects of filtration, storage, etc., on the nitro- 
genous organic matter in water. 98 
INTERPRETATION OF RESULTS. 
Nitrogen as Nitrites.—Nitrites are present in water 
as the result either of incomplete nitrification of ammonium, 
or the reduction of already formed nitrates, under the in- 
fluence of reducing agents or microbes. Since they are 
transition products, their presence in water is usually 
evidence of existing fermentative changes, and, further, 
may be taken as indicating that the water is unable to 
dispose of the organic contamination. When, however, 
the conditions are such that oxidation cannot take place, 
nitrites may persist for a long time. This sometimes 
occurs in deep waters in which fermentative changes have 
long since ceased, but oxygen is not available. These 
contain not infrequently small amounts of nitrites, to 
which the same degree of suspicion cannot be attached. 
When nitrites are found in these waters, the possibility of 
their introduction from polluted subsoil water, through 
defective tubing, must not be overlooked. Rain water, 
also, sometimes contains nitrites derived from the air, 
and therefore not indicative of any putrefactive change. 
The presence of measurable quantities of nitrites in river 
or subsoil water is sufficient ground for condemnation. 
Nitrogen as Nitrates.—Nitrates are the final point 
in the oxidation of nitrogenous organic matter, especially 
animal matters. Rain water and that from mountain 
streams and deep wells, except from cretaceous strata, 
generally contain only traces, but river and subsoil waters 
will always contain appreciable amounts, unless some re- 
ducing action, such as recent sewage-pollution, is at work. 
When, therefore, a water contains enough mineral matter 
to demonstrate its percolation through soil, and at the 
same time is free from nitrates or contains only traces, the 
occurrence of a destructive fermentation may be inferred. SANITARY APPLICATIONS. 
99 
These cases are not uncommon among well-waters, and 
the samples are generally turbid from suspended organic 
matter. Decided departure, either by increase or de- 
crease, from the proportion of nitrates usual in the same 
class of water in any district may be taken as evidence of 
contamination. 
Oxygen-consuming Power.—Sanitary authorities 
differ very much as to the significance of this datum. At- 
tempts have been made to fix maximum limits for the vari- 
ous types of water, and also to gauge the character and 
condition of the organic matter by observing the rate at 
which the oxidation takes place, but no positive conclu- 
sions can be given. In general, it may be said that a 
sample which has high oxygen-consuming power will be 
more likely to be unwholesome than one which is low in 
this respect; but the interferences are so numerous, and 
the susceptibility to oxidation of different organic matters 
of even the same type, is so different, that the method is at 
best only of accessory value. It is especially suitable for 
consecutive determinations on the same supply. 
The following proportions are given by Frankland and 
Tidy as the basis of interpreting the results of this 
method :— 
Oxygen Absorbed in Three Hours. 
High organic purity, 05 parts per million. 
Medium purity, 0.5 to 1.5 “ “ “ 
Doubtful, 1.5 to 2.1 “ “ “ 
Impure, ........ over 2.1 “ “ “ 
For the method with acidified permanganate at the boil- 
ing heat, the German chemists, who employ it largely, re- 
gard an absorption of 2.5 parts of oxygen per million 
as suspicious, and some sanitary authorities have fixed INTERPRETATION OF RESULTS. 
3.8 parts of oxygen per million as the highest permissible 
limit. 
Dissolved Oxygen.—Full aeration of water is favor- 
able to the destruction of organic matter ; a decided dimi- 
nution in the quantity of dissolved oxygen may show excess 
of such matter and of microbic life. Gerardin has pointed 
out that this diminution is associated with the development 
of low forms of vegetable life, and Leeds has recorded 
similar facts. These changes are more likely to take place 
in still waters, and are frequently accompanied by disagree- 
able odor and taste. In cases in which stored waters be- 
come unpalatable, these facts should be borne in mind. 
Dupre has given the following as the basis for interpret- 
ing the results of his adaptation of the determination of 
dissolved oxygen :— 
“ A water which does not diminish in its degree of aera- 
tion during a given period, mayor may not contain organic 
matter, but presumably does not contain growing organ- 
isms. Such organic matter as it may be found to contain 
by chemic analysis need not be considered as dangerous 
impurity.” 
“A water which by itself, or after the addition of gela- 
tin or other appropriate cultivating matter, consumes oxy- 
gen from the dissolved air, at lower temperatures, but does 
not consume any after heating for, say, three hours at 
140° F., may be regarded as having contained living or- 
ganisms, but none of a kind able to survive exposure to 
that temperature.” 
“A water which by itself, or after addition of gelatin 
or the like, continues to absorb oxygen from the contained 
air after heating to 140° F., may be taken as containing 
spores or germs able to survive that temperature.” SANITARY APPLICATIONS. 
101 
Hardness.—The degree of hardness has but little bear- 
ing on the sanitary value of water, but is important in 
reference to its use for general household purposes, in view 
of the soap-destroying power which hard waters possess. 
USUAL ANALYTIC RESULTS FROM UNCON- 
TAMINATED WATERS. 
Milligrams per Liter. 
Rain. 
Surface. 
Subsoil. 
Deep. 
Total solids, 
Chlorin, 
Nitrogen by permanganate, 
“ as NH4, . . . . 
“ " nitrites, . . . 
“ “ nitrates, . . . 
S to 20 
Traces to i 
.08 to .20 
.20 to .50 
.None or 
traces. 
Traces. 
15 upward 
1 to 10 
.05 to ,15 
.00 to .03 
None 
.75 to 1.25 
30 upward 
2 to 12 
.05 to .10 
.00 to .03 
None 
i-5 to 5 
45 upward 
Traces to large 
quantity 
.03 to .10 
Generally high 
None or traces 
.00 to 3 
Inferences from Culture-Methods.—Owing to the 
great differences in the conditions and manner of growth 
in various species of microbes, the inferences to be drawn 
from the cultivation of the germs present in a water-sample 
are uncertain. In spite of the study which has been given 
to the subject, the differentiation of specific forms has not 
reached exactness, nor have the conditions most favorable 
to growth been ascertained. Different observers pursue 
different methods of culture, and the results are not com- 
parable. Broadly speaking, the examination of the bacte- 
rial life in water may include two inquiries,—a simple cal- 
culation of the number of individual living microbes, and 
the detection of the presence of certain specific forms. 
Even the first of these objects, though simple, cannot be 
carried out with absolute certainty at the present day. The 
number of microbes in water is subject to rapid increase INTERPRETATION OF RESULTS. 
102 
for a brief period after collection of a sample, and may 
be greatly modified by incidental conditions during stor- 
age or transportation, so that little value can be attached to 
quantitive determination, except when made promptly. 
The culture-fluids ordinarily used, and the conditions in 
which the culture takes place, do not suffice for the devel- 
opment of all the forms present. The cultivation ought 
to be extended over many days, and samples of the water 
tried with various nutritive media and at different tempera- 
tures to secure a knowledge of the forms present. As an 
indication of the insufficiency of the common methods, 
it may be mentioned that Miller describes six species of 
microbes occurring in the human mouth, none of which 
would grow on any form of culture-medium which he 
was able to produce. 
It is necessary that any record of bacteriologic examina- 
tion of water should include a precise statement of the 
conditions of cultivation. That is, composition of the 
culture-medium; if alkaline or acid, the degree of this 
reaction expressed in terms of some standard solution ; the 
temperature at which the cultivation takes place, and the 
time. It is not correct to record the number of individual 
colonies observed on the culture-field as indicative of so 
many living microbes, for in some cases two or more 
microbes may have been jointly concerned in the formation 
of a colony. A proper method is simply to enter the 
observation as so many points of microbic life, and to add 
whatever detailed description is necessary. Efforts have 
lately been made to secure a consensus of opinion among 
bacteriologists as to the most satisfactory method of 
microbe-counting, and to adopt this as a uniform system, 
in order that results in some degree comparable may be SANITARY APPLICATIONS. 
obtained by different observers. At a convention held 
under the auspices of the American Public Health Associ- 
ation in New York City, June 21st and 22d, 1895, the 
first step in this direction was taken, but the methods are 
not yet sufficiently developed to be inserted. 
In the determination of specific forms far greater diffi- 
culty arises, and unfortunately this difficulty concerns 
especially the great problem which is presented to the 
sanitary chemist, namely, whether a given water-supply is 
likely to produce disease. The recognition of so charac- 
teristic a form as the comma-bacillus in water is not very 
difficult, but it is a problem rarely presented to those chem- 
ists who are practicing in civilized countries. The history 
of the attempts to determine bacilli of objectionable char- 
acter in water has presented a continuous evolution, in 
which a degree of confidence existing at onetime has been 
overturned by later discoveries. It was first thought that a 
distinction might be made between ordinary water-bacteria 
and sewage-bacteria, by reason of the action of the latter 
upon the gelatin culture-medium. Some bacteria grow 
without altering the condition of the gelatin visibly ; others 
rapidly digest it and produce a liquid peptone. It was 
supposed that these latter were the more objectionable 
forms, and some chemists still record the liquefying 
microbes as “ sewage microbes.” This distinction is, how- 
ever, untenable. Several bacilli known to be associated 
with intestinal discharges do not produce any liquefaction, 
while some that are harmless rapidly liquefy. 
The method used in the Hygienic Laboratory of the 
University of Michigan has the sanction of high authority 
and the benefit of extended experience, but it is doubtful 
if it meets the requirements of the sanitary chemist. 104 
INTERPRETATION OF RESULTS. 
However general the acceptance of the method by physi- 
ologists, it cannot be considered safe to infer that germs 
which are poisonous when injected subcutaneously or intra- 
abdominally into rats, guinea-pigs, rabbits, and mice, are 
necessarily dangerous in water consumed in the ordinary 
way by human beings. Tests of this kind require the very 
highest skill and facilities, involve great expense and delay ; 
and it is probable that in a large majority of cases a careful 
analysis upon the lines generally accepted will afford as safe 
a ground for inference as this elaborate method. It is not 
impossible that treatment at blood-heat and in a highly 
stimulating nutritive medium may materially increase the 
virulence of some microbes. 
There is, however, one field of inquiry in which even 
mere microbe-counting has value, and that is in comparing 
samples of the same water before and after some treatment 
or other incident. In these studies the method is suffi- 
ciently free from fallacy to make the results trustworthy 
when they are conducted in a strictly uniform manner; 
thus, if a river-water supplied to a filter be studied daily 
by examination of repeated samples before and after filtra- 
tion, inoculating separate portions of the same culture- 
medium, and multiplying the results to such an extent as 
to eliminate accidental differences, a comparison between 
the water before and after filtration may be safely made as 
to the proportion of microbes removed. Moreover, spe- 
cial microbes of highly characteristic properties may be 
introduced in large quantities into the water, and by sub- 
sequent culture the extent to which these are removed may 
be satisfactorily recognized. Thus in the extended ex- 
periments of the Massachusetts State Board of Health the 
Bacillus prodigiosus was employed as a test-microbe, its SANITARY APPLICATIONS. 
chromogenic power enabling it to be detected with great 
facility. It is said in these reports that the life-history and 
habits of this microbe are so nearly identical with that of the 
B. typhosus that it is conveniently substituted for the latter 
in such test experiments. Under the B. typhosus the 
Massachusetts observers refer to a microbe which is 
obtained from blood and viscera of patients dead of 
typical typhoid fever. Concerning the alleged specific 
nature of this microbe, B. typhosus, or B. typhi-abdominalis, 
as it has been called (the latter an unfortunate term be- 
cause it perpetuates a highly inappropriate name for ty- 
phoid-fever), it must be noted that there is no satisfactory 
evidence as to the existence of a distinct, differentiated, 
specific form, which is the sole and only cause of the fever. 
The old method of recognizing the B. typhosus, by culti- 
vation on potato, was never regarded as very satisfactory, 
and is now known to be valueless. Research has indicated 
that several common water-bacteria may assume temporary 
conditions, known as “ involution-forms,” in which they 
may have functions different from those ordinarily belong- 
ing to them. Among the bacilli that seem to be closely 
associated with those forms that have been designated as 
B. typhosus, is one which is extensively present in the 
intestinal contents of man and the domestic animals, and 
which is designated as the B. coli-communis. It is abun- 
dantly present in water which has received any form of 
sewage, even when that is merely surface-washings. It is 
not necessarily associated with danger to those drinking 
the water, but its presence must be regarded as suspicious. 
It has undoubtedly been designated as B. typhosus in many 
cases, and we now know enough of the errors of this class 
of investigation to say positively that a large proportion INTERPRETATION OF RESULTS. 
of the earlier literature on this subject is without value. 
Since it appears that B. coli-communis is the germ most 
likely to be confounded with the specific typhoid-causing 
germ, if such exists, the efforts of observers have been 
directed toward indicating the specific differences as 
clearly as possible. Unfortunately, these differences 
appear to be entirely negative as to the more important 
form, rendering its detection in the presence of the more 
positive form impossible. Thus it is said that the B. coli- 
communis does not curdle milk, while B. typhosus does. 
The former is said to induce fermentation in sugar- 
solutions, and to furnish the indol-reaction in beef-peptone, 
while the latter produces neither of these effects. A 
French observer, however, claims that by growing the B. 
typhosus under new conditions the reactions of the B. coli- 
conwiunis may be produced. A competent American 
writer has recently stated that “ between what we may 
regard as typical forms of the B. coli-communis, on the one 
hand, and typical forms of the B. typhosus, on the other, 
there is a whole series of intestinal bacilli known under 
%'arious names and described by various bacteriologists, 
representing a perfect gradation from one microbe to the 
other.” Klein states that the true typhoid-germ produces 
an iridescent film on solid gelatin at ordinary temperatures 
after a few days’ growth, and that a precipitate is formed 
in melted gelatin at 370 C., neither of which actions is 
exhibited by B. coli-communis. 
Another water-microbe that has ordinarily no signifi- 
cance of danger is the B. fluorescens liquefaciens, but the 
observations of Moore (Bureau of Animal Industry, No. 
3), show that cultures of this microbe suddenly take on 
septic properties and lose them again subsequently. ACTION OF WATER ON LEAD. 
107 
Vaughan (Amer. Jour. Med. Sci., August, 1892, p. 198), 
has expressed himself as follows in regard to the specificity 
of B. typhosus :— 
“ Of one thing I am certain, and that is, that I am 
ignorant of any crucial test, or of any combination of 
tests, upon the strength of which I can say at present that 
a germ which I may find in drinking-water is identical with 
the so-called typhoid bacillus. I have found in spleens, 
after death from typhoid fever, germs which differ from 
the typhoid bacillus obtained from Berlin, and from one 
another as markedly as my B. venenosus differs from either 
or both.” 
ACTION OF WATER ON LEAD. 
The almost universal use of lead pipes for conveying 
water, and the facility with which some waters corrode 
and dissolve the metal, make it a question of moment to 
determine the cause of this action and to devise means for 
its prevention. The subject has received considerable 
attention within the last few years, and the conditions which 
determine corrosion are now fairly understood. As a rule, 
it is found that waters free from mineral matter dissolve 
lead with facility, especially in the presence of oxygen. 
Some very soft waters are entirely without action, and 
this was unexplained until a few years ago, when Messrs. 
Crookes, Odling, and Tidy found that the action was con- 
trolled by the amount of silica contained in the water. 
They found that those soft waters which, when taken from 
the service pipes, contained a notable quantity of lead, 
gave, on the average, three parts of silica per million ; in 
those in which there was no lead, the silica present 
amounted to 7.5 per million, and in those in which the 108 
INTERPRETATION OF RESULTS. 
action was intermediate, 5.5 parts per million. That it 
was really the silica that conditioned the corrosion, was 
confirmed by laboratory experiments. They also found 
that the most effective way of silicating a water is by passing 
it over a mixture of flint and limestone. The reason for 
this was pointed out later by Messrs. Carnelly and Frew, 
who showed that while calcium carbonate and silica both 
exert a protective influence, calcium silicate is more 
effective than either, and, further, that in almost all cases 
in which corrosion took place it was greater in the presence 
of oxygen. This is particularly the case with potassium 
and ammonium nitrates and with calcium hydroxid. rlhe 
reverse is true of calcium sulphate, which is more corrosive 
when air is excluded. Their experiments also show that 
the presence of calcium carbonate or calcium silicate, 
altogether prevents corrosion by potassium and ammonium 
nitrates. 
As the result of an elaborate series of experiments, Mul- 
ler concludes, that while chlorids, nitrates, and sulphates 
all act upon lead pipes, no corrosion takes place in the 
presence of sodium acid carbonate, and that calcium car- 
bonate, by taking up carbonic acid, acts in the same way. 
This latter conclusion is at variance with the observations 
of Carnelly and Frew, who found that calcium carbonate 
is equally effective when carbonic acid is excluded. Mul- 
ler also states that surface waters, contaminated by sewage 
and containing large amounts of ammoniacal compounds, 
will dissolve lead under all circumstances. 
Allen has shown that water containing free acid, in- 
cluding sulphuric acid, acts energetically upon lead. This 
is not surprising in view of the later experiments, which 
prove that even calcium sulphate is corrosive. Later, W. TECHNIC. APPLICATIONS. 
109 
Carleton-Williams found that even in the presence of free 
acid, corrosion may be prevented by the addition of suffi- 
cient silica. His experiments also confirm the view gener- 
ally held, that soluble phosphates protect lead to a marked 
degree. 
The following is a summary of the more important ob- 
servations on this subject:— 
Corrosive : Free acid or alkalies, oxygen, nitrates, par- 
ticularly potassium and ammonium nitrates, chlorids, and 
sulphates. 
Non-corrosive and preventing corrosion by the above : 
Calcium carbonate, sodium acid carbonate, ammonium 
carbonate, calcium silicate, silica, and soluble phosphates. 
It is said that filtration through animal charcoal is a 
means of removing the greater portion of any lead sus- 
pended or dissolved in the water. Such filters must be 
attended to and renovated from time to time. 
Boiler Waters.—The main conditions affecting the 
value of a water for steam-making purposes are its 
tendency to cause corrosion and the formation of scale. 
Corrosion may be due to the water itself, to the presence 
of free acids, or to substances which form acids under the 
influence of the heat to which the water is subjected. 
Pure water, e. g., distilled water, exhibits a powerfully 
corrosive action upon iron. The dissolved oxygen which 
all waters contain also aids in the corrosion, and especially 
when accompanied, as is usually the case, by carbonic 
acid. There is always greater rusting at the point at 
which the water enters the boiler, since there the gases are 
driven out of solution and immediately attack the metal. 
TECHNIC APPLICATIONS. INTERPRETATION OF RESULTS. 
This is an evil that obtains with all waters, and it is not 
customary, in making examination for technical purposes, 
to determine the amount of these bodies. In water that 
has had free access to air, the oxygen in solution is a 
tolerably constant quantity, and it is sufficient to note the 
temperature and refer to the table of amounts of oxygen 
dissolved in water. The corrosive action of oxygen and 
carbonic acid is especially noticeable in waters that are 
comparatively pure, such as those derived from mountain 
springs. This was repeatedly observed by Dr. William 
Beam, in the examination of the waters used for the 
locomotives of the Baltimore and Ohio Railroad. The 
waters which caused the most corrosion were mainly those 
containing small quantities of solid matter, the full amount 
of oxygen and considerable carbonic acid, but no other 
acid or acid-forming body. 
Free acid, other than carbonic acid, is not often found 
in water, and if present renders the water unfit for use, 
unless it be neutralized. Mine waters are the most likely 
to contain free acid, sulphuric acid being generally 
present. Sometimes the acidity is due to organic acids. 
These act very injuriously on iron. Allen gives an ex- 
ample of this in the water supplied to Sheffield, Eng., 
which he found to contain an organic acid in amount 
equivalent to from 3.5 to 10 parts of sulphuric acid per 
million. 
Magnesium chlorid is frequently present in waters, and 
if in considerable quantity may be very harmful. At a 
temperature of 310° F., corresponding to an effective 
pressure of four atmospheres, magnesium chlorid reacts 
with water to form magnesium oxid and hydrochloric acid, 
the latter attacking the boiler, especially at the water line. TECHNIC APPLICATIONS. 
If there is present at the same time considerable calcium 
carbonate the evil may be somewhat lessened, but as Allen 
has pointed out, and as we also have noticed, there may 
still be corrosion, so that the presence of more than a small 
quantity of the salt, say a grain or two to the gallon, may 
be considered objectionable. Allen remarks that the 
presence of a certain amount of sodium chlorid may 
prevent this decomposition, the two chlorids combining 
to form a stable double salt. The addition, therefore, of 
common salt to a water containing magnesium chlorid may 
act to diminish corrosion, a point which will bear further 
investigation. 
It has not been determined how far the presence of 
nitrites, nitrates, and ammonia affects the quality of water 
for steam-making purposes; but it is more than probable 
that they act harmfully, especially the nitrates, which are 
frequently present in large amount. 
Scale is composed of matters deposited from the water 
either by the decompositions induced by the heat or by 
concentration. When the deposit is loose it is termed 
sludge or mud, and usually consists of calcium carbonate, 
magnesium oxid and a small amount of magnesium car- 
bonate. The magnesium oxid is formed by the decompo- 
sition of the magnesium carbonate and chlorid. This fact 
was first pointed out by Driffield (y. Soc. Chem. Ind., vi, 
178). 
The formation of sludge is the least objectionable effect, 
since it may readily be removed by “blowing off,” pro- 
vided that care is previously taken to allow the flues to 
cool down so that when the water is removed the heat of 
the flues may not bake the deposit to a hard mass. Waters 
containing calcium sulphate form hard incrustations diffi- INTERPRETATION OF RESULTS. 
I 12 
cult to remove and causing great loss of fuel by interfering 
with the transmission of the heat to the water. It not 
only forms a hard incrustation in itself, but becomes in- 
corporated with the mud, and renders it also hard. The 
hard scale will also contain practically all the silica and 
the iron and aluminum present in the water, besides any 
matters originally held in suspension. 
It follows from the above that a water only temporarily 
hard will, if care is taken in the management of the boiler, 
cause the formation merely of a loose deposit of sludge— 
temporary hardness being due in the main to calcium and 
magnesium carbonates. A water permanently hard will 
probably form a hard scale, since such hardness is usually 
due to calcium sulphate. 
In accordance with these principles, the analysis of a 
water for steam-making purposes may include the deter- 
minations of free acid, total solid residue, S04, Cl, Ca, Mg, 
temporary and permanent hardness. In cases in which the 
qualitative tests show but small amounts of S04 and Cl, 
the analysis may be limited to the determinations of the 
temporary and permanent hardness. 
It has been pointed out in an earlier chapter that it is 
not possible to deduce from the analytic result the exact 
forms in which the various elements are combined, but 
since it is known that at the high temperature ordinarily 
reached in boilers definite chemical changes occur, it is 
safest to exhibit the maximum amount of corrosive and 
scale-forming ingredients which the water under these cir- 
cumstances could develop. Thus, since calcium sulphate 
is practically insoluble in water above 212° F., the pro- 
portion of calcium sulphate may be regarded as such as 
would be formed by the total quantity of calcium or the TECHNIC APPLICATIONS. 
total quantity of S04, according to which is present in the 
larger amount. Similarly, as the decomposition of magne- 
sium chlorid is induced by the high temperature of the 
boiler, the analytic statement should indicate the maxi- 
mum proportion of this compound obtainable from the 
magnesium and chlorin present. These rules cannot apply 
absolutely to waters rich in alkali-carbonates, since these 
would neutralize any acid formed from the magnesium 
chlorid, or even prevent its formation, and would prevent 
to a large extent the formation of calcium sulphate. Much 
remains to be determined concerning the effects of the 
high temperature and concentration to which boiler waters 
are subjected. 
General Technic Uses.—In regard to the quality 
of water for technic other than steam-making purposes, 
such as brewing, dyeing, tanning, etc., no detailed meth- 
ods or standards can be laid down. The nearest approach 
to purity that can be secured in the supply will be of the 
greatest advantage. The more objectionable qualities will 
be large proportion of organic matter, especially if it dis- 
tinctly colors the water, excessive hardness, and notable 
amounts of iron or free mineral acid. It is stated by 
Bell (Jour. Soc. Chem. Ind.') that one part per million of 
iron will render water unsuitable for bleaching establish- 
ments. It has been noted that a large proportion of active 
microbes is injurious in the manufacture of indigo. In 
artificial ice making, a very pure water must be used if 
a clear and colorless product be desired. Any suspended 
or dissolved coloring matter will be concentrated by the 
freezing and appear in the bottom or center of the mass. 
The Antwerp water, purified by the Anderson process, is 114 
INTERPRETATION OF RESULTS. 
used with entire satisfaction for the manufacture of artifi- 
cial ice in that city. 
The examination of sewage-effluents and waste waters 
from manufacturingestablishments is to be conducted upon 
the same principles as for ordinary supplies, but especial 
attention must be given to the presence of poisonous 
metals, and free mineral acids. The latter interfere with 
the normal self-purification of the water. For the nitro- 
gen determination, the Kjeldahl process will be found 
more satisfactory than that by alkaline permanganate. 
PURIFICATION OF DRINKING-WATER. 
The most obvious method of purifying water is by dis- 
tillation. The process is too expensive for general use, but 
is especially adapted for water intended for pharmaceutical 
or chemical purposes. It has also been used for supplying 
vessels at sea and in tropic localities in which the natural 
waters may be contaminated with malarial or other germs. 
The majority of microbes are killed by short exposure to a 
temperature of 212° F. ; hence, water may be purified, on 
a small scale, by simple boiling. Freezing does not have 
the same effect, many microbes retaining vitality for a long 
while in ice. 
The self-purification of water, that is the destruction of 
organic matter and pathogenic microbes, by reason of the 
development of the ordinary microbes of putrefaction, 
occurs satisfactorily only in alkaline waters, hence, acid 
effluents check this process. The addition of lime in suffi- 
cient amount to give a slightly alkaline reaction will be 
beneficial. 
The conditions necessary to secure self-purification of PURIFICATION OF DRINKING-WATER. 
surface waters are not fully understood, and it is unsafe to 
state that a polluted stream will purify itself in any given 
distance. It must also be remembered that the dilution 
of infected sewage by its introduction into a large volume 
of uninfected water will assist, for a time, at least, the 
multiplication of pathogenic microbes. 
Heider made a study of the water of the Danube. Al- 
though there is not complete commingling for several 
miles after the sewage inflow, yet, as soon as the sewage is 
diluted somewhat more than seven times, the analytic dif- 
ferences between the river water above and that below the 
contaminating inflow are exceedingly small, yet the bacteria 
remain several times as numerous for miles down stream 
after the introduction of the sewage-water. Muscle-tissue 
stained by bile was found after the water had flowed for 
twenty-five miles. The current of the river is from four to 
seven miles an hour. Gruber and von Kerner have shown 
that cholera germs can remain alive for from five to seven 
days in the river-water, as also in the Vienna aqueduct- 
water. Hence the self-purification is a matter of dilution, 
and, as elsewhere, should not be relied upon when epi- 
demics of water-borne infectious diseases are present. Pu- 
pils of Pettenkofer who studied the Isar water at Munich, 
consider that self-purification within twenty miles was there 
more reliable and certain. Fraenkel has recently found 
that the Lahn purified itself speedily after the sewage of 
Marburg entered it.—(iV. V Med. Jour., Dec. i, 1894.) 
The methods in general use for purifying water are 
simple filtration and the removal of the impurities by ap- 
propriate chemical agents. 
Filtration.—For household purposes forms of carbon, 
stone and sand filters are used, which yield clear filtrates, 116 
INTERPRETATION OF RESULTS. 
but permit, sooner or later, the transmission of microbes. 
The suspended matter in the water gradually accumulates 
on the surface of the filter, and causes a great increase in 
the number of the microbes, some species of which appar- 
ently grow through the pores of the filter, and are carried 
into the filtrate. The following are among the more 
efficient forms of household filters: — 
Bischof Spongy-Iron Filter.—The construction of this is 
shown in Fig. io. The spongy iron is obtained by re- 
ducing hematite, at a temperature 
below the fusing point of iron. 
It rests on a layer of pyrolusite 
(manganese dioxid), below which 
is an asbestos bag having a short 
tube with perforated cap. This is 
a very efficient form, removing 
much of the dissolved organic mat- 
ter, and practically all the sus- 
pended matter, including the mi- 
crobes. 
Chamberlain-Pasteur Filter. — 
This consists of tubes of unglazed 
biscuit-ware, the number depending 
on the size and required delivery 
of the filter. There are arrange- 
ments for continuous filtration by attaching the tube to the 
faucet; also forms adapted to simultaneous cooling and 
filtration. The observations of Pasteur and others have 
shown that this is a highly efficient filter, yielding for a 
considerable time a filtrate entirely sterile. It requires 
occasional cleaning, since, after continuous use, the mi- 
crobes may pass through the pores, probably by a process 
Fig. io. PURIFICATION OF DRINKING-WATER. 
117 
of growth. An occasional boiling of the tubes in water 
would be sufficient to overcome this difficulty. 
Fig. ii shows a form of sand filter which is used in the 
laboratory of Professor Kemna, at Antwerp. A moderately 
wide and stout tube is 
passed to the bottom of a 
tall jar, and the interven- 
ing space filled to the depth 
of about 25 cm. with fine 
sand, coarse sand, and 
gravel, as shown. The 
exit tube consists of a 
siphon, the outer leg oi 
which does not quite reach 
to the level of the surface 
of the sand, the inner leg 
reaching to the bottom of 
the jar. The flow may be controlled by a stop-cock at- 
tached to the outer leg. The object of this arrangement 
is to prevent the water-level being drawn to or below the 
level of the sand. The filter should be supplied from a 
reservoir by means of a siphon, the exit tube of which is 
curved upward, in order to prevent disturbing the deposit 
which collects on the surface of the filter. 
Fig. ii. 
The filter may be cleaned by removing the siphon and 
sending a slow current of water down the wide tube until 
the deposit upon the surface of the sand is washed out. 
The apparatus is especially suited for laboratory experi- 
ments on filtration. 
Man)' other forms of filter have been devised. Com- 
prehensive comparative tests made under the auspices of 
the British Medical Journal show that, except as to those INTERPRETATION OF RESULTS. 
based on the principle of the Chamberlain-Pasteur filter, 
but little time elapses before the filtrate contains numerous 
microbes. 
For the purification of drinking-water on a large scale, 
sand filter-beds have been found to be efficient; but the 
best results are obtained only under proper supervision. 
Numerous determinations of the efficiency of sand filter- 
ing basins have been made by various methods. It has 
been found that, at the start, a large proportion of the 
organic matter, dead and living, passes through; but that 
as filtration proceeds, the surface of the sand becomes 
covered with a close deposit, which acts both as a means 
of retaining suspended impurities and, by its active micro- 
bic life, destroys the organic matter in a manner analogous 
to that occurring in soil. The water thus becomes prac- 
tically free from microbes, but after a time these gradu- 
ally penetrate the pores of the filter and appear in the 
filtrate. Increase of pressure will hasten this effect. 
Bertschinger (Jour. Soc. Chem. Ind., Dec., 1889) has 
published observations on the efficiency of the sand filters 
in use at the Zurich Water-works. The filtering material 
rests on a brick grating, and consists of the following 
layers, commencing at the bottom :— 
Five to 15 cm. of coarse gravel, 10 cm. of garden gravel, 
15 cm. of coarse sand and 80 cm. of fine sand. As soon 
as the diminution in pressure of water, due to the resistance 
of the filter, is from 60 to 80 cm., the filter is cleaned by 
allowing the water to run off and removing the top layer 
of sand to a depth of two cm., as this is found to contain 
the whole of the mud. The filter is then filled up with 
filtered water from below, and washed by allowing this to 
overflow. After filtration has recommenced, the first PURIFICATION OF DRINKING-WATER. 
portion of the filtrate is rejected. Two of the filters are 
arched over; these require cleaning once in seventy-seven 
days, the others once in forty-eight days. As soon as the 
layer of fine sand has been reduced to the thickness of 50 
cm., fresh sand is substituted or more added, until the 
depth is again 80 cm. Among the conclusions reached 
are the following :— 
119 
Under normal conditions the filtered water is free from 
microbes, although a few are taken up again in the later 
stages of the filtration. 
After cleaning the filter, the water which first passes 
through is not in normal condition. It contains many 
microbes, the efficient layer of scum not having had time 
to collect on the sand, though the chemical purity of the 
water is satisfactory. 
When the filters have not been used for some time, the 
water which first passes through them contains more bac- 
teria than usual, owing to their rapid multiplication in 
stagnant water, but its chemical purity is not materially 
different from the normal filtered water. 
Sand-filtration has been brought to practical use at Law- 
rence, Massachusetts, where a filter has been in operation 
for several years, with the effect of markedly reducing the 
death-rate from typhoid-fever in that city. The water 
supplied is that of the Merrimack River, which ten miles 
above the Lawrence intake receives the sewage of Lowell, 
a town of 80,000 population. The following is a descrip- 
tion of the Lawrence filter given by Mr. George W. Fuller, 
biologist in charge of the Lawrence Station. It was 
designed by Hiram F. Mills, Engineer-member of the 
Massachusetts State Board of Health. 
It is 2.5 acres in area, and contains sand of an average INTERPRETATION OF RESULTS. 
depth of about 4.5 feet. The depth of sand varies from 
three to five feet, but owing to the arrangement of the 
underdrains all water passes through at least five feet of 
filtering material. The filter is situated by the side of the 
Merrimack River, and separated from it by an embank- 
ment. Its surface is two feet below low water in the river. 
The water is allowed to flow on to the filter about 16 hours 
a day on an average, and during the remainder of the time 
the sand is drained and the pores filled with air. The 
filtered water is conducted by underdrains to a collecting 
conduit, and thence to the pump-well. The pumps deter- 
mine the rate of filtration, and are speeded so that the 
water shall pass through the filter at the rate of 2,000,000 
gallons per acre per day. From the pumps the water 
passes to the open distributing reservoir, which is 25 feet 
deep at high water and contains 40,000,000 gallons. The 
water then flows by gravity from the reservoir to the con- 
sumers. 
From the time when the filter was put in operation, Sep- 
tember 20, 1893, until May 1, 1894, daily bacteriologic 
tests, in addition to numerous analyses, were made of the 
water before and after its passage through the filter, as it 
leaves the reservoir, and from taps at the City Hall and 
Experiment Station, which are distant 1.5 and 2.5 miles, 
respectively, from the reservoir. The results were as fol- 
lows : — 
River, 
Average number of 
bacteria in one c.c. 
Percentage 
removed. 
Effluent at Filter, 
97-58 
. “ “ Reservoir Outlet, . . 
... I30 
98.73 
“ “ City Hall, 
... 90 
99.17 
“ “ Experiment Station, . 
... 82 
99-25 PURIFICATION OF DRINKING-WATER. 
121 
The above averages include all results. Excluding those 
results obtained under conditions which were abnormal 
and are not likely to occur again, we find that this filter 
normally reduced the bacteria from 9000 to 150 per cubic 
centimeter, a removal of 98.3 per cent, of the number 
applied. Owing to the fact that some ground water of 
somewhat unsatisfactory quality with regard to numbers of 
bacteria was at times mixed with the effluent, it is very 
improbable that all the bacteria in the water pumped to the 
reservoir passed through the filter. 
The following account of some details of the construc- 
tion of filters for sewage-purification has been furnished 
me by H. W. Clark, Chemist at the Massachusetts Experi- 
ment Station, Lawrence, Mass. : The sands in use in the 
large filter vary in effective size from .04 mm. to 1.40 mm. 
That is to say, the finest ten per cent, of the material is 
composed entirely of grains whose diameter is less than 
.04 mm. in the finest material used, and less than 1.40 mm. 
in the coarsest. With coarse and medium-fine sand a 
filter contains but one grade throughout the entire five 
feet. With fine sands, trenches are sometimes dug one 
to two feet deep, and filled with coarser sand. This gives 
a given area greater filtering capacity. With what is con- 
sidered the best grade of sand the applied dose of sewage, 
one hundred thousand gallons per acre per day, passes 
below the surface of the sand in a time varying from ten 
minutes to one-and-a-half hours, depending mainly on the 
condition of the surface of the filter. The remainder of 
the twenty-four hours the surface is uncovered. In the 
intermittent filtration of water as now practiced at this 
station, the surface of the filter is uncovered two hours out 
of the twenty-four. INTERPRETATION OF RESULTS. 
122 
The liability to the free passage of microbes for a short 
time after filter-cleaning has been often alleged as a draw- 
back in the use of sand-filtration. It is thought that 
the formation of a close film of microbes upon the surface 
of the filter is necessary to perfect working, but the obser- 
vations at Lawrence have indicated that this period of 
diminished efficiency is due in part to the mechanical 
disturbance of the main body of the filtering material, 
during the process of refilling with water after the draining 
and scraping. Slowly filling the filter from below upward 
has been found to be a reliable method of avoiding the 
difficulty. It is stated by Mr. Fuller that a much greater 
speed than 2,000,000 gallons per acre per day can be em- 
ployed without diminishing the efficiency for at least a time, 
but it is not yet known how this will affect the permanent 
efficiency of the filter. 
Precipitation Methods.—The observations of Dr. 
P. F. Frankland and others have established the following 
points :— 
“ Organized matter is, to a large and sometimes to a most 
remarkable extent, removable from water by agitation with 
suitable solids in a fine state of division, but such methods 
of purification are unreliable. 
“ Chemical precipitation is attended with a large reduc- 
tion in the number of microorganisms present in the waters 
in which the precipitate is made to form and allowed to 
subside. 
“ If subsidence either after agitation or after precipita- 
tion be continued too long, the organisms first carried down 
may again become redistributed throughout the water.” 
It is essentia], therefore, that the liquid be filtered as 
short a time after the precipitation as possible. PURIFICATION OF DRINKING-WATER. 
123 
Precipitation by Aluminum Compounds.—A small quantity 
of aluminum sulphate added to natural waters is decom- 
posed with the formation of a flocculent precipitate of 
aluminum hydroxid, which settles comparatively rapidly, 
and carries down with it all suspended matters, as well as 
a large proportion of the dissolved organic matters. 
Waters which contain such an excess of organic matter as 
to be distinctly colored, may usually be made quite clear 
and colorless by this treatment. One grain to the gallon 
will suffice for the purpose, but if very rapid subsidence is 
desired more may be added. 
This precipitation is a gradual process, and a water that 
will give the test for aluminum immediately after filtering 
may give none after twenty-four hours. It is not infre- 
quently noted that such effluents, originally clear, become 
cloudy on standing, in consequence of the separation of 
aluminum hydroxid. On the addition of aluminum sul- 
phate to brown surface-waters there is also a precipitation 
by the organic matters. A sample of the Cochituate-river 
water (Boston supply), of moderately deep color, to which 
25 milligrams of alum to the liter had been added, when 
filtered gave no reaction, even when 2.5 liters were con- 
centrated for the test. An addition of 30 milligrams to 
the liter could be detected without difficulty. 
Several systems of filtration now in extended use employ 
this precipitation method in conjunction with filters of 
small area, the necessary flow being obtained by increased 
pressure. The differences between the various forms are 
chiefly in the mechanical arrangements for supplying the 
water and for cleaning the filter. The material is generally 
sand or coke ; the cleaning is performed at short intervals, 124 
INTERPRETATION OF RESULTS. 
by means of reverse currents of water. The aluminum 
solution is introduced as needed by automatic apparatus. 
These filters are efficient, and are suitable for the purifi- 
cation of water for manufacturing establishments, and when 
large basins are not available. 
The addition of an iron salt to water containing carbon- 
ates, is attended with decomposition and the formation of 
a precipitate of ferric hydroxid. This reaction has been 
employed with great advantage as a means of purification. 
One of these methods was by passing the water through 
spongy iron, then aerating to precipitate the iron, and fil- 
tering through sand. The method is very efficient, but the 
spongy iron gradually chokes by oxidation and becomes 
useless. This difficulty is removed by the use of iron bor- 
ings or punchings, contained in an iron cylinder (Anderson 
and Ogston, Proc. Inst. Civ. Png.,Yol. 81), which is rotated 
while the water passes through; the iron is brought into 
thorough contact with the water, and there is sufficient 
abrasion to keep its surface clean. 
The apparatus as practically employed is shown in Fig. 
12. It consists of a cylinder rotating in a horizontal position, 
attached to the internal periphery of which are short curved 
shelves, arranged at equal distances. Pipes enter the hollow 
trunnions to admit and discharge the water. As it enters 
the cylinder, the water strikes against a circular distributing 
plate, and is caused to flow radially through a narrow an- 
nular space, to prevent the formation of a central current 
along the axis of the purifier. The inner end of the out- 
let pipe carries an inverted bell-mouth which catches the 
fine particles of the iron carried forward by the water, Fig. i2. 126 
INTERPRETATION OF RESULTS. 
and causes them to fall again to the bottom of the cylinder. 
Sufficient borings or punchings to one-tenth fill the 
cylinder are introduced, and the purifier is then completely 
filled with water, and set in motion, the rate of rotation 
being about six feet per minute at the periphery. The 
effect of the rotation is to scoop up the iron particles and 
to shower them down through the flowing water. 
The effect is due mainly to the formation of ferrous 
carbonate, through the action of the carbonic acid of the 
water. On issuing into the open air this is gradually con- 
verted by oxidation into the insoluble ferric hydroxid, 
which carries down much of the organic matter and sub- 
sequently oxidizes and destroys it. Temporary hardness 
is also decreased by the abstraction of the carbonic acid 
and consequent precipitation of calcium and magnesium 
carbonates. 
The time of contact with the iron depends upon the 
purity of the water. For Antwerp water, which is purified 
by this means, the maximum effect is accomplished in 3.5 
minutes. After leaving the cylinder, the water is passed 
through sand filters. Analytic examinations show the effluent 
water to be of high organic purity and practically sterile. 
Cast-iron borings are much more readily acted upon 
than steel punchings. The latter suffice in operating upon 
water rich in dissolved organic substances, carbon dioxid 
and suspended matters, while the former are especially 
suited for treatment of water comparatively pure, and, 
therefore, less active. 
For determining the most advantageous method of treat- 
ing any water supply, laboratory experiments may be made 
as follows:— 
A strong wide-mouth bottle holding about 2000 c. c., is PURIFICATION OF DRINKING-WATER. 
127 
charged with one-tenth its bulk of clean borings or punch- 
ings, filled completely with water and shaken for four min- 
utes, in such manner that the iron particles are continuously 
showered through the liquid. The water is then aerated 
by agitating it in a large, thoroughly clean glass-stoppered 
bottle. With some (e. g., peaty) waters, it will be of 
advantage to allow about 200 c. c. of air to remain in the 
bottle in which the shaking with iron is performed, occa- 
sionally removing the stopper to renew the air. (Con- 
tinuous aeration during treatment is provided for in the 
apparatus used on the large scale.) The liquid is allowed 
to stand from a few minutes to four hours, depending on 
the rapidity with which the iron separates, and is then 
filtered through the sand filter (Fig. n), or through a well- 
washed cotton plug inserted in the neck of a funnel. Sat- 
isfactory purification as regards ammonium compounds 
cannot be obtained, but with proper attention to cleanliness, 
the figures for total organic nitrogen, nitrogen by perman- 
ganate, and oxygen-consuming power will be trustworthy. 
The following results were obtained by Dr. Beam and 
myself in the treatment of Delaware River water at Lard- 
ner’s Point pumping station, Philadelphia. The purifier 
was capable of delivering 100,000 gallons per 24 hours. 
All figures are in parts per million. 
September, 1890. 
Before Treatment. After Treatment. 
Nitrogen as ammonium, .04 .03 
“ as permanganate, .27 .09 
November, 1890. 
Nitrogen as ammonium, 
.084 
.034 
“ by permanganate, 
.091 
.049 
“ as nitrites, 
traces. 
none. 
The apparatus was subsequently transferred to Belmont INTERPRETATION OF RESULTS. 
pumping station, Philadelphia, and bacteriologic examina- 
tions made. The applied water was taken from Belmont 
reservoir which was supplied from the Schuylkill River. 
The cultivation was made in alkaline meat-extract-peptone- 
gelatin at ordinary temperatures. The figures represent the 
number of points of microbic life in one c. c. of the 
sample. 
Date. 
Applied water. 
Effluent water. 
Nov. II, 
innumerable 
36 
“ l3> 
4,900 
32 
“ 3°. 
2,860 
49 
Dec. 7, 
22,4.00 
79 
“ n, 
17,100 
. S6° 
“ 14, 
16,000 
60 
“ 18, 
14,500 
27 
The sample for December 11 was taken just after filter- 
cleaning. Moreover, the weather had been very cold and 
a film of ice formed around the sides of the tank and over 
the bottom; the expansion of this ice pushed the sand 
away from the sides of the tank. A thaw occurred and a 
space was left all around the sand-bed through which the 
water passed without proper filtering. 
Laboratory experiment on a sample of water from the 
Mississippi River at Memphis, Tenn. 
Before Treatment. 
After Treatment. 
Oxygen absorbed at 2120 F., 2.88 
O.36 
In the laboratory of the State Board of Health of Massa- 
chusetts Dr. Drown investigated the effect of various 
methods of aeration, such as exposing water in bottles to 
the air of the room, drawing a current of air through by 
means of an aspirator, shaking it in a bottle by machin- 
ery, and exposing it to air under pressure of from 60 to 
75 pounds. While no appreciable benefit as far as re- PURIFICATION OF BOILER WATERS. 
129 
gards the organic matter and its decomposition-products 
occurs, aeration appears to prevent the growth of algse, 
with the troublesome accompaniments of bad tastes and 
odors. It may also have a beneficial effect upon ground- 
waters containing considerable amounts of iron. These 
waters are often clear when first drawn, but become turbid 
and yellow in a few hours by the separation of ferric- 
hydroxid by oxidation. Waters from considerable depth 
often contain so little free oxygen that this oxidation does 
not occur until they reach the surface. By applying an 
aeration method the change may be hastened, and by some 
simple process of rapid filtration afterward applied, the 
water will be made clear and remain so. 
A material, designated by the patentee as “ magnetic 
carbid of iron,” has been used for the purification of sew- 
age. It is made by heating hematite with coke and saw- 
dust, so as to reduce the ore to the composition of mag- 
netic oxid. 
Purification of Boiler Waters.—The problems pres- 
ent in the treatment of boiler waters are usually the 
removal of the calcium carbonate and sulphate, and magne- 
sium carbonate and chlorid. Both carbonates are appreci- 
ably soluble in pure water. About one grain of calcium 
carbonate to the gallon is usually stated to be the propor- 
tion dissolved, but it has been pointed out by Allen that 
solutions can be obtained containing twice this amount. 
If the water contains carbonic acid it will take up a much 
greater proportion of the carbonates, but in this case they 
will be deposited from the solution by boiling. This has 
been accounted for by supposing the existence of soluble 
bicarbonates, which are decomposed by the boiling. INTERPRETATION OF RESULTS. 
Nearly all of these carbonates can be thrown out of solution 
by any means that will deprive the water of the carbonic 
acid. Sodium hydroxid is often employed for the purpose, 
and should be added in quantity just sufficient to form 
normal sodium carbonate. If there are present in the 
water calcium and magnesium chlorids and sulphates, these 
also will be decomposed and precipitated by the sodium 
carbonate so formed. If the amount of sodium carbonate 
formed is not sufficient to decompose all of these bodies, 
a sufficient quantity should be added with the sodium 
hydroxid to effect the complete decomposition. The pre- 
cipitate is allowed to settle or filtered off. 
In cases in which the feed-water is heated before it enters 
the boiler, it may only be necessary to add to the water 
sodium carbonate in quantity sufficient to decompose the 
calcium and magnesium chlorids and sulphates, since the 
heat' alone will suffice to throw down the carbonates. 
Care should be taken in these precipitations that no more 
sodium hydroxid is added than is required for the precipi- 
tation, since any excess would tend to corrode the boiler. 
Clark's process consists in treating the water with calcium 
hydroxid (lime-water). This precipitates the calcium and 
magnesium carbonates by depriving the water of its free 
carbonic acid. It has, of course, no effect upon the cal- 
cium sulphate. It is to be noted that the proportion of 
calcium hydroxid which is to be added must be calculated 
from the amount of free carbonic acid existing in the water, 
and not from the amount of carbonates to be removed. 
The precipitate will usually require at least twelve hours 
for complete subsidence, but after three or four hours the 
water will be sufficiently clear for some purposes. If a 
filter press is used, as in Porter’s process, the time required PURIFICATION OF BOILER WATERS. 
131 
for clarification is very much shortened. Another advan- 
tage of this process is the use of a solution of silver nitrate, 
in order to determine more conveniently the proportion of 
calcium hydroxid which is to be employed. The lime is 
first slaked and dissolved in water, and the water to be 
softened run in and thoroughly mixed with it. From time 
to time small portions are taken out and a few drops of a 
solution of silver nitrate added. As long as the lime is in 
excess a brownish coloration is produced. When this has 
become quite faint, and just about to disappear, the addi- 
tion of the water is discontinued, and, after a short time, 
the water is filtered by means of the press. 
Soluble phosphates added to a water, precipitate com- 
pletely in a flocculent condition any calcium, magnesium, 
iron, or aluminum. This reaction can be best applied by 
using the tri-sodium phosphate (Na3P04 -f- i2H20), which 
is now a commercial article. By reason of the facility with 
which this substance loses a portion of its sodium to acids, 
it acts not only as a precipitant to the above materials, but 
will neutralize any free mineral acid present in the water. 
From evidence submitted by those who have used the pro- 
cess on the large scale, it appears that not only is no hard 
scale formed, but that scale already existing prior to its 
use is gradually disintegrated and removed with the sludge. 
Experiments indicate that no injury results from an excess 
of the material; but the economical employment of the 
method, especially with very hard waters, can only be 
based upon a correct analysis, and an estimation of the 
phosphate required for the precipitation. In many cases 
the composition of the water will be such that a partial 
precipitation will be sufficient. INTERPRETATION OF RESULTS. 
Of late years considerable success has been obtained by 
the use of fluorids as precipitants of scale-forming elements. 
Waters rich in ferrous compounds may be purified by 
thorough aeration and filtration, the iron being separated 
as ferric hydroxid. Simple filtration through a bed of 
manganese dioxid will accomplish the same purpose. 
IDENTIFICATION OF THE SOURCE OF WATER. 
The determination of the course of underground streams, 
and of communications between collections of water, is 
often an important practical problem. In geologic and 
sanitary surveys, valuable information may occasionally be 
gained. The method generally pursued when connection 
between water at accessible points is to be detected, is to 
introduce at one point some substance not naturally exist- 
ing in the water, and capable of recognition in small 
amount. Lithium compounds are among the best for this 
purpose. They are not frequent ingredients of natural 
waters, and are easily recognized by the spectroscope. 
Lithium chlorid is the most suitable. The quantity to be 
employed will vary with circumstances. It scarcely needs 
to be stated that the waters under examination should be 
carefully tested for lithium before using the method. 
When the lithium method is inadmissible, recourse must 
be had to other substances of distinct character, such as 
strontium chlorid, but this possesses the disadvantage that 
a considerable amount may be rendered insoluble, and 
thus lost in the ordinary transit through soil. Recently, use 
has been made of organic coloring matters of high tinct- 
orial power, one of the most suitable of which is fluores- 
cein, C20H12O3, a derivative of benzene. This will com- 
municate a characteristic and intense fluorescence to many IDENTIFICATION OF THE SOURCE OF WATER. 
thousand times its weight of water. An entire river may 
be colored by a few kilograms. By its use an under- 
ground communication was demonstrated to exist between 
the Danube and the Ach, a small river which flows into 
the Lake of Constance. The coloration is distinct only 
in alkaline liquids. Other colors, such as anilin-red, 
may be employed. For detecting leakage from cesspools 
and cisterns, sanitary inspectors occasionally employ water 
colored by Prussian blue. 
I am indebted to Dr. F. P. Vandenburgh, who conducted 
the investigation, for a description of an instance of the 
application of the above methods. In a suit at law grow- 
ing out of use of a creek for the supply of Syracuse, 
N. Y., it was alleged that the creek supplied a spring 
which was used by a manufacturing establishment. Tests 
of the water of creek and spring for lithium were made, 
ten gallons of each being evaporated, with negative 
results. Twenty-five pounds of lithium carbonate were 
converted into chlorid and poured into the stream about 
half a mile from the spring. Samples of ten gallons each 
were taken out of the spring by almost continual dipping 
during forty-eight hours following. Twenty of these 
samples were examined and lithium found in each. 
Ten pounds of fluorescein were introduced at a point 
about one mile above the spring and the characteristic 
fluorescence appeared at the spring about six hours after 
its introduction into the creek. The greatest intensity of 
color was between six and ten hours after its introduction. 
A more important feature of the problem in a sanitary 
point of view is the determination of the source of a 
given current or collection of water, when such source is 
inaccessible. Problems of this character are not infre- 
quent in large cities in which the systems of water supply INTERPRETATION OF RESULTS. 
134 
and drainage are defective, thus giving occasion to 
accumulations of water in cellars and similar places. 
Often, in these cases, no extended explorations can be 
made, by reason of the adjacent buildings and conflicting 
property interests, and the question may arise whether the 
water proceeds from a leaky hydrant, drain, sewer, or sub- 
soil current. It is obvious that in the case of the collection 
of water in a cellar from causes other than surface wash- 
ings or entrance of rain, it must have passed through some 
distance of soil, and in built-up districts will almost cer- 
tainly be charged with organic refuse. To correctly 
interpret the results, it will be necessary to know the 
general character of the subsoil water of the district and 
the composition of the public supply. As a rule, the 
transmission of water through moderate distances of soil 
will not materially increase the mineral constituents. 
Hence, if the sample contains an excess of dissolved mat- 
ters as compared with the water supply of the district, it 
may reasonably be inferred that it is derived from a drain, 
sewer, or subsoil current. 
In these investigations it will generally be sufficient to 
determine the total solids, odor on heating, chlorin, 
nitrates and nitrites. The following figures are from some 
results obtained in investigations made in association with 
Mr. Chas. F. Kennedy, Chief Inspector to the Board of 
Health of this city :— 
City Supply. 
Cellar Water. 
No. 1. No. 2. 
No. 3. 
Total solids, . . . 
• . 115 
I40 
661 
640 
Odor on heating, . 
. . faint 
faint 
strong urinous 
Chlorin, .... 
• • 4 
6.4 
77.0 
128.0 
N as nitrates, . . 
. . 0.7 
1.0 
3-5 
none 
“ “ nitrites, . . 
. . none 
present 
present 
none IDENTIFICATION OF THE SOURCE OF WATER. 
135 
Sample No. i was taken from a cellar in which a small 
amount of water had been almost constantly present for a 
long time, and of which the source could not be ascertained. 
The results of analysis led to the view that since it resem- 
bled in composition the city supply, it was derived from 
a leaky hydrant pipe. The parties in interest were not in- 
clined to accept this opinion, but the examination of the 
condition of the hydrant on an adjacent property showed 
a leak, which being repaired the water ceased to appear in 
the cellar. In this case it was found that the water had 
passed through twenty-two feet of earth. In the second 
case the sample is seen to be very impure, and it was sug- 
gested that it was derived directly from a leaky drain, 
which upon exploration proved to be the case. In the 
third sample, the high chlorin, strong urinous odor and 
absence of nitrates and nitrites, pointed unmistakably to 
recent and profuse contamination with sewer water. 
Occasionally the analytic results will be ambiguous, and 
it is advisable to make examinations of more than one 
sample, since accidental circumstances, rain-fall, etc., may 
affect the composition of the water. 
Instances of the contamination of water by unusual sub- 
stances are occasionally noted, and these sometimes afford 
a clue to the source of the water. Among the instances 
of this kind withitl my own experience may be noted the 
contamination with petroleum and with soap. In the 
former case it was evident that the contamination was from 
a leaky pipe connecting two refineries. In the latter it 
was shown to be derived from an adjoining building used 
as a laundry. ADDENDA. 
To page 6j. 
Extended observations, especially in Massachusetts, 
have shown that reservoirs intended for even moderately 
prolonged storage of water should be clean, that is, or- 
ganic matter of any kind should not be allowed to accu- 
mulate on the bottom and sides. Dr. Drown states {Rep. 
S. B. of H. of Mass., 1891) that while the water in one 
basin became foul from stagnation, in another which was 
carefully prepared by the removal of all soil and vegetable 
matter, and is supplied by a brown, swampy water from a 
district almost entirely free from pollution, the water is 
good at a depth of forty feet. 
In Philadelphia, where large storage reservoirs are used 
for water that is often very muddy, but little trouble from 
the growth of microscopic organisms occurs. These reser- 
voirs are artificial basins. 
To page 64. 
Owing to the great differences in the size of micro- 
scopic organisms, the mere enumeration of their numbers 
is not always an index of the amount of living matter in 
suspension. To obviate this, Mr. Geo. C. Whipple, biolo- 
gist to the Boston Water Board, has suggested a standard 
unit of size, estimating by means of it the total volume of 
the organisms, and not their number. He finds by this 
method that the analytic and biologic results correspond 
much more closely than when mere numbers are recorded. 
The unit is an area of 400 microns, that is, a square of 20 ADDENDA. 
137 
microns on a side. The results are stated in number of 
standard units per c. c. A detailed account of the method 
and of some results obtained by it will be found in The 
Amer. Month. Mic. Jour., 1894, p. 337. 
Mr. Whipple has investigated the conditions influencing 
the growth of the microscopic organisms in water. He finds 
that diatoms thrive best with a supply of nitrates and a 
free circulation of air ; temperature alone has no very 
direct effect. Infusoria will be found in largest numbers 
when the water contains the greatest amount of finely 
divided organic matter. When the conditions bring about 
a circulation of the water, the organisms are not only 
brought constantly in contact with new food materials, but 
are enabled to reach the upper layers of the water where 
oxygen is abundant. 
To page 65. 
In a private communication of recent date, from Mr. 
George W. Fuller, of the Experiment Station at Lawrence, 
Massachusetts, I am furnished with the following informa- 
tion of great practical value in the bacteriologic examina- 
tion of drinking water. At this station the methods for 
the isolation of the so-called typhoid bacillus are those 
described in the “ Report of the Massachusetts State Board 
of Health ” for 1891, page 637. The only additional step 
is to employ Wurtz’ litmus-lactose-agar. This consists of 
nutrient agar-agar of definite reaction. See below for 
the methods for determining reaction, to which 2 to 3 per 
cent, of lactose is added. It is sterilized and then enough 
sterilized litmus solution added to give a decided blue tint. 
The bacilli included under the designation B. typhus abdom- 
inalis do not produce fermentation with this medium, but 138 
ADDENDA. 
some common water-bacteria do. (Abbott, “Manual of 
Bacteriology.”) This is found to be of much assistance. 
The methods are employed with reasonable confidence 
at Lawrence, where the observers are fairly familiar with 
the bacterial flora of the water examined. Concerning 
waters from elsewhere much significance is attached to the 
presence or absence of the B. coli communis. 
Mr. Fuller has also favored me with a comprehensive ab- 
stract of a valuable communication presented by him to the 
Convention of Bacteriologists, to which reference is made 
on page 103. After discussing the influence of reaction 
upon the various phenomena taking place in culture-media, 
it was pointed out that all regular culture-media as used 
are, strictly, neither neutral, acid, or alkaline, but the 
reaction depends upon the indicator used. Many are 
alkaline to litmus and acid to phenolphthalein ; the cause of 
this is twofold,—the presence of acid phosphates and of 
proteids; the latter are amphoteric, but the acid reaction 
predominates. Phenolphthalein is the best and most deli- 
cate agent for determining reaction in culture-media. 
Under ordinary circumstances the phosphate present is 
Na2HP04. To all other indicators, except turmeric and 
phenolphthalein, this salt is alkaline, to the latter it is neu- 
tral. Experiments have shown that this phosphate exerts 
little influence upon bacterial development; in fact, it is 
less active than sodium chlorid. Hence, with litmus as an 
indicator, this compound reacts alkaline and prevents a 
proper addition of alkali, and as the amounts of phosphates 
vary in different lots of culture-media, the degree of reac- 
tion cannot be accurately controlled by means of litmus. 
Mr. Fuller recommends “ neutrality to phenolphtha- 
lein”asa “datum point” for reaction. The expression ADDENDA. 
139 
of the reaction in parts or in percentage is inaccurate and 
awkward. It is suggested that all reaction be expressed in 
terms of normal solution necessary to render one liter of the 
medium neutral to phenolphthalein. As, ordinarily, the 
media are acid, it is convenient to call the acid number 
plus, alkaline minus. 
The procedure at Lawrence is to get all ingredients in 
solution, mix well, place 5 c. c. in a 15 cm. porcelain 
dish, add 45 c. c. of distilled water, boil three minutes, 
titrate with “ alkali, using phenolphthalein as an indicator, 
calculate the amount of normal alkali necessary to make 
the main bulk of the solution neutral, heat for the usual 
period, filter, and titrate again. The solution is now rather 
acid, and hydrochloric acid is added in such amount that 
to make one liter of the medium neutral to phenolphthalein 
15 c. c. of normal alkali is necessary. This is for special 
work. In general work, using 1 c. c. of the water-sample 
to 5 c. c. of culture-medium, the acidity is increased one- 
fifth to offset the dilution. 
The following table, condensed from Mr. Fuller’s com- 
munication, shows very clearly how reaction influences the 
number of points of microbic life developed in any given 
sample, and confirms the observations on page 102. 
c. c. of Normal Solu- PniM-re m 
Microbic Life in 
One c. c. 
tion Required to 
Neutralize One ' 
Liter of the Cul- Lamrence S e_ 
ture-Medium. & 
Merrimack River 
Water. 
Filtered Water. 
40 168,000 
IOO 
4 
25 1,720,000 
7,800 
84 
20 2,688,000 
15,000 
184 
5 2,625,000 
6,900 
80 
0 2,234,000 
5,800 
66 
— 10 2,230,000 
3,200 
48 
— 25 1,520,000 
200 
13 
— indicates alkalinity to phenolphthalein. 140 
ADDENDA. 
As an illustration of the difficulty of recognizing a 
specific typhoid germ I may mention that, although there 
is every reason to believe that the Schuylkill water supplied 
to Philadelphia causes considerable typhoid fever, Dr. A. 
C. Abbott, of the Department of Hygiene of the Uni- 
versity of Pennsylvania, informs me that he has never 
been able to find in that water the typical bacillus. ANALYTIC DATA. 
Parts per 100,000 X -7 — Grains per Imperial Gallon 
“ “ 1,000,000 X -07 = “ “ “ “ 
“ “ 100,000 x >583 = “ “ U. S. “ 
“ “ 1,000,000 X -OSS = “ “ “ “ 
“ “ 1,000,000 X •°°833 = Pounds per 1000 U. S. Gal. 
Grains'* Imp, gallon -4- .7 = Parts per 100,000 
“ “ “ “ .07 = “ “ 1,000,000 
“ “ U. S. “ -4- .583 = “ “ 100,000 
“ “ “ “ -4- .058 = “ “ 1,000,000 
FACTORS FOR CALCULATION. 
Parts per 100,000 divided by 2 and quotient increased one-tenth gives 
approximately grains per U. S. Gallon. 
a12°3- X -S29 = A1 
AgCl, X -247 = Cl 
BaSOt X -588 = Ba 
BaS04, X -412 = S04 
B203 X -314 == B 
CaO X -7!4 = Ca 
CaC03, X *4° = Ca 
Cl, X 1-65 = NaCl 
Fe203, X -7 = Fe 
KC1 X -524 — K 
2KCI, PtCl4 X .16 = K 
2KC1, PtCl4, X -30 = KC1 
MgjPj°7> X -218 = Mg 
Mg2p2°7. X -853 = P04 
MnS, X -63 2 = Mn 
NaCl, . X -393 = Na 
N X 4*43 =NOs 
N, X 3-28 = N02 
N X 5-85 = Ca(N03)2 
NH3 X 823 = N CONVERSION TABLE. 
CONVERSION TABLE. 
Parts 
per 
Million 
Grains per 
U. S. Gallon. 
Grains 
per 
Imp. Gal. 
Parts 
per 
Million. 
Grains per 
U. S. Gallon. 
Grains 
per 
Imp. Gal. 
i 
.058 
.07 
26 
I.508 
1.82 
2 
.Il6 
.14 
27 
I.566 
I.89 
3 
.174 
.21 
28 
I.624 
1.96 
4 
.232 
.28 
29 
I 682 
2.03 
5 
.290 
•35 
30 
I.740 
2.IO 
6 
•348 
.42 
31 
I.798 
2.17 
7 
.406 
•49 
32 
I.856 
2.24 
8 
.464 
•56 
33 
I.914 
2.3I 
9 
.522 
•63 
34 
I.972 
2.38 
IO 
.580 
.70 
35 
2.030 
2.45 
11 
.638 
•77 
36 
2.088 
2.52 
12 
.696 
.84 
37 
2.146 
2-59 
13 
•754 
.91 
38 
2.204 
2.66 
14 
.812 
.98 
39 
2.262 
2-73 
15 
.870 
1.05 
40 
2.320 
2.80 
16 
.928 
1.12 
41 
2.378 
2.87 
17 
.986 
1.19 
42 
2.436 
2.94 
18 
1.044 
1.26 
43 
2.494 
3°l 
19 
1.102 
i-33 
44 
2-552 
3.08 
20 
1.160 
1.40 
45 
2.610 
3-i5 
21 
1.218 
i-47 
46 
2.668 
3.22 
22 
1.276 
i-54 
47 
2.726 
329 
23 
1 334 
1.61 
48 
2.784 
3-36 
24 
1.392 
1.68 
49 
2.842 
3-43 
25 
1.450 
i-75 
50 
2.900 
3-5° TABLE OF DISSOLVED OXYGEN. 
Dibdin’s Table of Oxygen Dissolved by Water at Various 
Temperatures, extended to Give the Weight of Oxygen 
Per Liter. Corrected to o° C. and 760mm. Pressure. 
Temperature 
Fahrenheit. 
410 . . 
Temperature 
Centigrade. 
Cubic Inches of 
Oxygen per Gallon 
(70000 Grains). 
Milligrams 
of Oxygen 
per Liter. 
42 . . 
• • 5 55 • • 
. . 2.074 . . . 
. . IO.72 
43 • • 
. . 6.11 . . 
. . 2.048 . . . 
. . IO.57 
44 • • 
. . 6.66 . . 
2.022 . . . 
. - IO.45 
45 • • 
. . 7.22 . . 
• • 1-997 • • 
. . IO.3O 
46 . . 
. . 7-77 • • 
. . 1.973. . . 
. . IO.18 
47 • • 
• • 8.33 . . 
. . 1.949 • • • 
. . IO.06 
48 . . 
. . 8.89 . . 
. . 1.927. . . 
- • 9-94 
49 • • 
. . 9.44 • • 
. . 1.905. . . 
• • 9-83 
50 . . 
. . 10.00 . . 
. . 1.884 . . . 
. . 9-72 
51 • • 
. 10.55 . . 
. . 1.864 • • 
. . 9.61 
52 • • 
. . 11.11 . . 
. . 1.844 • • • 
• 9 5i 
53 • • 
. .11.66 . . 
. . 1.826 . . . 
. . 9.42 
54 • • 
. . 12.22 . . 
. . 1.808 . . . 
• • 9-33 
55 • • 
. . 12.77 . . 
. . 1.791 . . . 
. . 9.24 
56 . . 
• • 13-33 • • 
. . 1.775 - • • 
• • 9-15 
57 • • 
. . 13.89 . . 
. . 1.760 . . . 
. . 9.08 
58 • • 
. . 1444 • • 
. . 1.746. . . 
. . 9.01 
59 • • 
. . 15.00 . . 
. . 1.732. . . 
- • 8.94 
60 . . 
• • 15-55 • • 
. . 1.719. . . 
. . 8.87 
61 . . 
. . 16.11 . . 
. . 1.706 . . . 
. . 8.80 
62 . . 
. . 16.66 . . 
. . 1.695. . . 
. . 8.74 
63 . . 
. . 17.22 . . 
. . 1.683 . . . 
. . 8.68 
64 . - 
• ■ 17-77 • • 
. . 1.674. . . 
. . 8.64 
65 . . 
. . 18.33 • • 
. . 1.667 . . . 
. . 8.60 
66 . . 
. . 18.89 • • 
. . 1.660 . . . 
. . 8.56 
67 . . 
. . 19.44 . - 
. . 1.652. . . 
. . 8.52 
68 . . 
. . 20.00 . . 
. . 1.644 . . . 
. . 8 48 
69 . . 
. . 20.55 . . 
. . 1.639 • • • 
• ■ 8.45 
70 . . 
. . 21.11 . . 
. . 1.634. . . 
■ • 8.43 
The table is calculated for a barometric pressure of 760 mm., and would require 
corrections for variations from this, but such corrections are mostly within the 
limits of experimental error. 144 
ANALYSIS OF RAIN AND SUBSOIL WATERS. 
ANALYSES OF RAIN AND SUBSOIL WATERS. 
Milligrams per Liter. 
- 
0 
•2 
s 
* 
h 
0 
S 
ffi 
O 
0 
From. 
cn 
c' 
Z 
55 
"rt 
O 
>» 
tn 
S 
O 
H 
X 
U 
z, 
£ 
& 
z 
Bellefonte—collected by 
Rain water. 
Prof. Wm. Frear, after 
long rain. 
5 
none 
0.148 
0.280 
none 
none 
Subsoil water. 
Wynnewood—pool fed 
by underground spring. 
6s 
6.20 
0.032 
0.024 
none 
2.3 
“ « 
Wy nnewood—well about 
150 yards from above. 
Wynne wood—well pol- 
60 
4.00 
0.024 
0.016 
none 
3-5 
a <t 
luted by farm-yard drain- 
age ; about 500 yards from 
pool. 
16.00 
0.208 
0.028 
none 
14.2 
Pump - well in densely 
“ 
populated district. Highly 
contaminated. 
1120 
57.0° 
1.00 
3.12° 
0.01 
33-o 
“ 
Newly dug well in popu- 
lated district. Highly con- 
taminated. 
620 
120.00 
0.08 
2.00 
0.03 
16.0 
Well at Barren Hill, 130 
feet deep. 
470 
120.00 
undet. 
undet. 
traces 
22 0 RESULTS FROM SCHUYLKILL RIVER. 
State of 
Condition. 
Total 
Nitrogen bv 
Nitrogen 
Nitrogen 
Nitrogen 
Weather. 
Solids. 
KMnG4. 
as NH4. 
as N02. 
as N03. 
Sept. 17. 
Continued 
Turbid. 
160 
.06 
.048 
None. 
•13 
“ 18. 
Continued 
rain. 
Muddy. 
160 
.09 
.020 
“ 
•34 
“ i9- 
Clear. 
Turbid. 
140 
.108 
.004 
Trace. 
•34 
<f 20. 
“ 
150 
.124 
None. 
Faint trace. 
•25 
“ 21. 
“ 
Less turbid. 
J5° 
.132 
None. 
•25 
** 22. 
“ 
Very muddy. 
180 
.180 
“ 
Faint trace. 
.25 
“ 24- 
“ 
Turbid. 
140 
• IOO 
None. 
■13 
“ 25. 
“ 
Slightly turbid. 
130 
.092 
•13 
“ 26. 
“ 
Slightly turbid. 
120 
.068 
.01 
.18 
“ 27. 
“ 
Very slightly 
turbid. 
110 
.056 
None. 
.18 
" 28. 
“ 
Very slightly 
turbid. 
105 
.052 
■36 
“ 29- 
Nearly clear. 
125 
.052 
.co8 
.70 
Oct. 1. 
140 
.052 
.012 
.70 
“ 2. 
it it 
125 
.044 
None. 
.40 
“ 3- 
“ 
it it 
120 
.080 
.0.6 
.68 
" 4- 
“ 
Clear. 
120 
.084 
.008 
.80 
“ 5- 
*' 
120 
.092 
.012 
.70 
“ 6. 
Rain. 
“ 
120 
.060 
.012 
.80 
“ 8. 
Turbid. 
15° 
.108 
.008 
.80 
“ 9- 
Clear. 
Slightly turbid. 
130 
.088 
.008 
.70 
“ 10. 
Almost clear. 
125 
.056 
.010 
.70 
“ II. 
Clear. 
ns 
.044 
.010 
.70 
RESULTS FROM SCHUYLKILL RIVER—Milligrams per Liter. 
Samples taken from hydrant at 715 Walnut Street. 146 
ANALYSES OF ARTESIAN WATERS. 
Philadelphia. 
Baltimore. 
Indiana. 
V 
> 
Broad and 
Chestnut Sts. 
73 
* 
9th and 
Chestnut Sts 
24th and 
Washington A 
15th and 
Walnut Sts 
Broad and 
Columbia Av 
Black's Islan 
Locust Point 
Ft. Wayne. 
Condition, . , 
Clear. 
Clear. 
Slightly 
turbid. 
Clear. 
Clear. 
Clear. 
Clear. 
Clear. 
Reaction, . . 
Alkaline. 
Alkaline. 
Alkaline. 
Alkaline. 
Alkaline. 
Alkaline. 
Alkaline. 
Alkaline. 
SiO, 
36.OO 
34-5° 
35.00 
24.00 
29.OO 
19.50 
4.00 
so4, . . . . 
61.80 
26.26 
9.90 
25.84 
15-24 
102.36 
4.10 
po4, . . . 
0.24 
O.3I 
O.3I 
1 race. 
1 race. 
0.38 
CO, (combined), . 
64.91 
110.17 
54.80 
78.84 
108.64 
50.64 
Cl, 
89.21 
9’-77 
Trace. 
108.50 
206.01 
172.00 
554-48 
4.68 
190.2 
H2S, . . . . 
Mn, 
1.80 
4.32 
Fe, 
9.80 
7.70 
5-7° 
5.28 
1.05 
Ca, 
54-57 
44.28 
50.00 
I25.CO 
101.42 
53-57 
2-5 
Mg, 
15-27 
7.98 
12.60 
30 70 
22.27 
6.48 
0.86 
Na, 
54-13 
84.13 
32.46 
72-34 
55-83 
378-63 
K, 
4.14 
8-54 
4.10 
1 races. 
6.28 
1 race. 
N by KMn04, 
0.032 
Not det. 
0.048 
0.048 
0.015, 
O.I48 
0.012 
0.035 
“ as NH4, . 
0.248 
Not det. 
0.034 
0.032 
0.004 
0.132 
O.O44 
0.315 
“ “ no2, . 
Trace. 
None 
None. 
0.02 
Trace. 
None. 
None. 
None. 
“ “ no3, . 
Trace. 
Trace. 
None. 
2.00 
I.OO 
None. 
None. 
None. 
*Mr. Wm. Glenn, Chemist of the Baltimore Chrome Works, kindly sent this sample. 
ANALYSES OF ARTESIAN WATERS. 
Milligrams per Liter. EXAMPLES OF CITY SUPPLIES. 
M7 
City 
New Yokk 
City. 
Brooklyn. 
Boston. 
Cincinnati. 
Chicago. 
Little 
Rock, Ark. 
Philadel- 
phia. 
Washing- 
ton, D. C. 
Class of Water, 
Surface. 
Subsoil. 
Surface. 
Surface. 
Surface. 
Surface. 
Surface. 
Surface. 
Total Solids, 
75-o 
64.O 
47.6 
156.0 
140.00 
136 0 
283.0 
120.00 
126.00 
Chlorin, .... 
2.8 
13-5 
5-i 
34-8 
14.00 
2.3 
8.2 
4.00 
2.8 
Nitrogen as Ni- 
trates, .... 
0.28 
16.0 
0.07 
o-S 
0.26 
Trace 
1.1 
1.00 
I .O 
Nitrogen as Ni- 
trites, .... 
None 
None 
0.001 
0.01 
None 
None 
.OOI 
Nitrogen as Am- 
monium, . . 
0.009 
0.001 
0.008 
0.38 
O.OO3 
0.005 
0.012 
0.01 
0.00 
Nitrogen by per- 
manganate, . 
0.06 
0.07 
0.16 
0.23 
0.09 
0.075 
0.13 
0.10 
0.12 
The figures are taken from official reports and do not represent averages of large numbers of analyses, but 
individual analyses of samples representative of the supplies. The figures for Boston water represent the 
Cochituate and Mystic rivers respectively. The Little Rock supply is in the unfiltered condition; much of 
the solid matter is in suspension. 
EXAMPLES OF CITY SUPPLIES. 
Milligrams per Liter. 148 
ANALYTIC DATA. 
CULTURE-PHENOMENA OF SOME IMPORTANT 
MICROBES. 
These data have been compiled principally from the 
writings of the Franklands (.Microorganisms in Water), 
Vaughan (Bad. of Drink. Water, Proc. Amer. Ass’n 
Physicians, 1892), and Mace (Tr. Prat. d. Bad.). The 
references are indicated by appropriate initials. 
In the first column -[- means “ liquefies,” O means “ does not liquefy.” 
“ second “ -f- “ “ aerobic,” — “ “ anaerobic.” 
iC 
r third 
and 
I fourth 
“ “ “ grows,” — “ “ grows feebly.” 
O “ “ does not grow.” 
The species marked * were described by Jordan (Rep. 
S. B. of H., Mass., 1890), having been obtained from the 
sewage of Lawrence. For an account of recent study of 
microbes in Ohio-River water, see a paper by John W. 
Hill (Trans. Amer. Soc. Civ. Eng., May, 1895). 
Under the term B. Aquatilis sulcatus, Weichselbaum has 
described five varieties designated by the numbers I to V. 
All but V grow somewhat at blood heat. CULTURE-PHENOMENA. 
149 
Action on 
Gelatin. 
Relation 
to Oxygen. 
Action of 
Parietti’s 
Solution. 
j Growth at 
Blood-heat. 
Bacillus albus, V., 
O 
+ 
O 
O 
“ “ anaerobus, V., 
O 
4- 
“ “ putridus, V., 
+ 
+ 
O 
O 
“ aquatilis sulcatus, F., . . 
O 
+ 
O 
— 
“ candicans,* F., , 
o 
+ 
+ 
“ chlorinus, M 
+ 
4- 
coli-communis, F. , 
o 
+ 
+ 
4- 
" cinnabareus, V., 
+ 
o 
“ circulans, F., 
. + 
+ 
“ cloacae,* F., 
+ 
+ 
+ 
“ delicatulus,* F., 
*4* 
+ 
+ 
“ erythrosporus, F., 
o 
+ 
“ figurans, V., 
+ 
+ 
O 
— 
“ flavus, M., 
+ 
+ 
“ fluorescens liquefaciens, V., . . . . 
+ 
+ 
o 
o 
“ “ non-liquefaciens, V 
o 
+ 
o 
o 
“ gasoformans, V., 
+ 
+ 
o 
o 
“ gracilis aerobiens, V., 
o 
+ 
o 
o 
“ “ anaerobiescens, V , 
o 
— 
4- 
— 
“ helvolus, V., 
+ 
+ 
o 
— 
“ hyalinus, F ,* 
4* 
+ 
+ 
“ invisibilis, V., 
o 
— 
+ 
+ 
“ lactis aerogenes, F., 
o 
+ 
4" 
“ liquefaciens albus, V., 
+ 
+ 
o 
o 
“ ochraceus, V., 
+ 
+ 
o 
o 
“ prodigiosus, M., 
+ 
+ 
o 
o 
“ reticularis,* F., 
+ 
+ 
“ rubescens,* F., 
o 
+ 
“ rubidus, V 
+ 
+ 
o 
o 
“ subflavus, V., 
o 
+ 
o 
0 
“ subtilis, M., 
+ 
+ 
“ superficialis, F., 
+ 
+ 
“ tholeideum, F., 
o 
+ 
+ 
“ typhi abdominalis, F., 
o 
+ 
+ 
+ 
“ ubiquitus,* F., 
o 
4* 
+ 
“ venenosus, V., 
o 
— 
+ 
+ 
“ brevis, V., 
o 
— 
+ 
+ 
“ “ invisibilis, V., 
o 
+ 
+ 
+ 
“ liquefaciens, 
+ 
— 
4" 
“ violaceus 
+ 
+ 
o 
o 
Micrococcus aquatilis, F., V 
o 
+ 
4~ 
+ 
“ albus, V., 
o 
+ 
o 
— 
•' “ invisibilis, V., .... 
o 
+ 
o 
— 
“ “ magnus, 
o 
+ 
o 
— 
“ (diplococcus) aquatilis, V., . . . 
o 
+ 
o 
o 
“ (streptococcus) “ ... 
o 
+ 
o 
o 
“ candicans, V., 
o 
+ 
o 
o 
“ F 
+ 
4- 
“ cereus,V., 
o 
+ 
o 
o 
“ luteus, V , 
o 
+ 
o 
o 
“ subflavus, V., 
o 
+ 
o 
— 
Spirillum cholerse, 
+ 
+ 
+ 
“ Finkleri, M., 
+ 
+ 
+ INDEX. 
A CIDS, action on lead, 108 
Actinic method for organic matter, 
So 
Action of water on lead, 107 
Aeration of water, 128 
Agar-agar, 66 
Albuminoid ammonia, 35, 96 
Alkali carbonates, determination cf, 82 
Alkaline permanganate, 33 
Allen, on boiler waters, 111 
, lead in water, 108 
, sulphuric acid in water, 111 
, test for zinc, 56 
Alum, action of, 123 
, test for, 58 
, use of, 102 
Aluminum, determination of, 58, 75 
, test for, 58 
, in scale, 112 
Amido-naphthalene, 44 
Ammonia, albuminoid, 35, 96 
, free, 34 
, free water, 31 
, from rain water, 95 
, process, 20 
Ammonium chlorid, standard, 31 
molybdate, 51 
picrate solution, 42 
Analysis, statement of, 89 
Analytic operations, 21 
Anderson and Ogsten, purification of 
water, 124 
Antwerp water, purification of, 126 
Artesian water, 13, 18 
waters, composition of, 146 
Arsenum, detection of, 56 
DACHMAN’S method, 36 
Bacilli species of, 149 
Bacillus typhosus, culture of, 72 
Bacteriologic examination, 61 
Barium, detection and estimation of, 55 
Barren Hill well, 20, 144 
Barus, Carl, suspended matters in 
water, 15 
Basin, platinum, 26 
Bicarbonates in water, 129 
Biologic examinations, 61 
Black’s Island well, 93, 146 
Blarez’ oxygen process, 51 
Boiler mud, hi 
water, 109 
water, points to be determined 
in, 112 
, purification of, 129 
, statement of results from, 
112 
Boric acid estimation, 85 
Bottle culture, 69 
for test solution, 33 
Burner, low temperature, 26 
/’"'ABCIUM bicarbonate, 129 
carbonate, action in boiler 
waters, no 
.solubility of, 112 
compounds, removal of, 130 
, determination of, 76 
hydroxid for purifying water, 131 
sulphate, insolubility of, 112 
sulphate, action in boiler water, 
112 
Carbonates, action on lead, 109 
•, determination of normal, 82 
Carbon filters, 115 
Carbonic acid, action of, 18 
, free, determination of, 84 
.effect on microbes, 71 
Caustic soda, use of, in boiler water, 
130 
Cellar waters, examination of, 134 
Chlorin, determination of, 28 
, significance of, 93 
Chromium, detection of, 55 
City supplies, 147 
Clarifying water, 23, 114 
Clark’s process for purifying water, 130 
Collection of samples, 20 
Color comparator, 38 
, determination of, 23 
, significance of, 91 
Comparison cylinders, 38 INDEX. 
Control determination, 27, 77 
Conversion of ratios, 142 
Cooper, A. J., delicacy of tests, 61 
Copper, detection of, 60 
sulphate, standard, 60 
zinc couple, 43 
Corrosion of boilers, no 
Cultivation of microbes, 67 
Culture-media, 67 
phenomena, 149 
TNEEP water, 18, 93, 146 
Demijohn for water samples, 21 
Denitrification, 18 
Dibdin, table of dissolved oxygen, 143 
Distilled water, wholesomeness of, 92 
Driffield, composition of boiler mud, 
in 
Drown, aeration, 128 
Drown and Hazen, ignition of residue, 
27 
Drown and Martin, nitrogen determina- 
tion, 35 
Dupre, dissolved oxygen, 54, 100 
E'ERROUS ammonium sulphate, 
standard, 52 
Ferric sulphate, standard, 57 
Filter paper, 23 
F'ilters, Bischoff’s, 116 
, Pasteur-Chamberlain, 116 
,sand, 118 
, spongy iron, 116 
Filtration, 115 
Fleck’s silver method, 50 
Fluorescein, use of, 132 
Frankland, purification by precipita- 
tion, 122 
and Tidy, standards of purity, 99 
, isolation of microbes, 73 
-■ -, nitrifying bacillus, 17 
Fuller, G. W., culture-media, 137 
sand filtration, 119 
GALLON, Imperial, 89 
, U. S., 89 
Gelatin culture-media, 67 
, liquefaction of, 70 
Gerardin, dissolved oxygen, 100 
Gill’s method, 41 
, method for lithium, 80 
T_T ARDNESS, determination of, 8t 
, permanent, 81 
, temporary, 81 
Hard scale, 112 
water, softening of, 130 
Hehner’s cylinders for color compari- 
son. 38 
, method for hardness, 82 
History of water, 13 
Hunt, T. Sterry, water in rocks, 16, 
Hydrogen sulpnid, titration of, 81 
T IDENTIFICATION of source of 
water, 132 
Imperial gallon, 89 
Interpretation of results, 89 
Indol reaction, 71 
Iodin, centinormal, 81 
Iron, action of, in purification, 124 
compounds, solution by water, 19 
, determination of, 57, 75 
, significance of, 93 
method, 38 
Koch’s culture method, 64 
T ACMOID, use of, 25 
Lead, action of water on, 107 
Lead, determination of, 59 
, nitrate, standard, 60 
Leeds, actinic method, 50 
, dissolved oxygen, 100 
Lime, purification of water by, 114, 130 
Lithium compounds, use of, 132 
, detection of, 86 
, separation of, 80 
Litmus, use of, 25 
Locust Point well, 20, 146 
TV/TAGNESIA in boiler sludge, m 
■*■*•*■ Magnesium, determination of, 75 
Magnesium chlorid, decompositions and 
effects of, too 
compounds, removal of, 130, 131 
Magnetic carbid, 129 
Mallet, ammonia process, 96 
Manganese, detection of, 58 
, determination of, 76 
Microbes, table of, 149 
Mine water, no 
•NTAPHTHYLAMINE, 44 
A ' Nesslerizing, 34 
Nessler reagent, 32 
Nitric acid, diluted, 57 
Nitrification, 17 
Nitrates, action in boilers, in 
, determination of, 41 
, formation of, 17 
, significance of, 98 
Nitrites, determination of, 44 
, formation of, 17 INDEX. 
r53 
Nitrites, significance of, 98 
Nitrogen in ammonium compounds, 29, 
94 
as nitrites, 44 
as nitrates, 41 
by permanganate, 96 
, oxidation of, 16 
, total organic, 38 
/"\DOR, determination of, 24 
from residue, 28 
, significance of, 91 
Organic matter, 16, 27, 90 
, oxidation of, 50 
, precipitation of, 123 
Oxygen consumed, 46 
consuming power, 46 
, amount of, dissolved, 143 
, dissolved, determination of, 51 
.dissolved, effects of, 100, no 
pARAMIDOBENZENE -Sulphonic 
acid, 44 
Parietti’s solution, 73 
Pasteur-Chamberlain filter, 116 
Permanganate method, 46 
standard, 47, 49 
Pettenkofer’s method for free carbonic 
acid, 84 
Phenol broth, 73 
disulphonic acid, 41 
Plienolphthale'in, use of, 25 
Phosphates, action on lead, 109 
, determination of, 51 
, significance of, 94 
•, use of, in purifying water, 131 
Plate culture, 67 
Platinum, preservation of, 25 
Porter’s process for purifying water, 
131 
Potassium, determination of, 79 
chromate solution, 28 
iodid solution. 41 
nitrate, standard, 47 
Potassium permanganate, alkaline, 33 
permanganate, decinormal, 52 
Potato culture, 66 
Preliminary examination, 21 
Pure water, corrosive action of, 109 
Purification of boiler water, 129 
of drinking waters, 114 
ID AFTER’S method, 62 
Rain water, 13, 95, 144 
Ratios, conversion of, 141, 142 
Reaction, 24 
Residue, charring of, 27 
Results, statement of, 89 
River water, 13, 14, 91, 145, 147 
Roll culture, 69 
OALT, action on boiler waters, in 
Samples, collection of, 21 
Sand filters, 118 
Sanitary application, 90 
examinations, 21 
Scale, hi 
Schuylkill River water, composition of, 
T4» 145 
Sedgwick’s method, 62 
Sewage, action of, 18, 98 
Silica, action of, in water, 107 
, determination of, 75 
in scale, 112 
Silicates, action on lead, 107 
Silver nitrate, standard, 28 
, test in Porter’s process, 
132 
nitrite, preparation of, 45 
test for organic matter, 50 
Sludge, hi 
Solids total, determination of, 25 
Solids, significance of, 92 
Sodium and potassium, separation of, 
79 
carbonate, solution of, 31, 39 
, standard, 81 
, use of, in boiler waters, 
130 
chlorid, standard, 28 
, determination of, 79 
hydroxid, solution, 39 
nitrite, standard, 45 
thiosulphate, 47 
Souice of water, tracing of, 132 
Smart, C., nature of organic matter, 96 
Specific gravity, 87 
Spectroscope, 85 
Spectroscopic examination, 85 
Spongy iron filters, 116 
Starch indicator, 48 
Sterilizer, 65 
Storage, effect of, 122 
Subsidence, promotion of, 15, 122 
Subsoil water, 15, 144 
Sulphanilic acid, 44 
Sulphids, formation of, 19, 92 
Sulphuretted hydrogen, determination 
of, 81 
Sulphuric acid, diluted, 49 
, standard, 81 
Surface water, composition of, 13, 14, 
145. 147 
Suspended matters, 14, 15 
/T'ASTE, significance of, 91 
Technic examinations, 109 
Tests for metals, delicacy of, 61 154 
INDEX. 
Tidy’s permanganate process, 47 
Tidy and Frankland, standard of purity, 
99 
, Odling and Crookes, lead in 
water, 107 
Tri-sodium phosphate, use of, for puri- 
fication, 131 
TTNCONTAMINATED waters, 101 
Unit standard, 136 
Urea, decomposition of, 95 
Urine in water, 95 
U. S. gallon, 89 
■\7AUGHAN, typhoid fever germ, 107 
” Vegetable matter, 28, 96 
Vegetable growth in water, 62 
TA7ATER, amount of, in rocks, 16 
Wanklyn, standards of purity, 97 
Whipple, unit measure, 136 
, growth of microscopic organisms, 
137 
Wurtz’ lactose-agar, 137 
detection of, 56 Catalogue No. 8. 
August, 1895. 
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Children, Diseases of 6 
Clinical Charts 6 
Compends 22 
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Headaches to 
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Medical Jurisprudence 13 
Microscopy 13 
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SUBJECT. PAGE 
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College. 
No. 16. DISEASES OF NOSE AND EAR. Illustrated. Same 
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is a reason for every word. They contain over 600 illustrations. Published Annually for 45 Years. 
THE PHYSICIAN’S VISITING LIST 
Special Improved Edition for 1896. 
LINDSAY & BLAKISTON’S). 
PRELIMINARY MATTER.—Calendar, 1896-7—Table of Signs, to 
be used in keeping records—The Metric or French Decimal System 
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