A 
PRACTICAL HANDBOOK 
OF 
MEDICAL CHEMISTRY 
APPLIED TO 
CLINICAL RESEARCH AND THE DETECTION 
OF POISONS. 
PARTLY BASED ON “BOWMAN’S MEDICAL CHEMISTRY.” 
BY 
WILLIAM H. GREENE, M.D., 
. DEMONSTRATOR OF CHEMISTRY IN THE MEDICAL DEPARTMENT OF THE 
UNIVERSITY OF PENNSYLVANIA ; EDITOR OF WURTZ’s ELEMENTS 
OF MODERN CHEMISTRY; MEMBER OF THE AMERICAN 
PHILOSOPHICAL SOCIETY, ETC. ETC. 
PHILADELPHIA: 
HENRY C. LEA’S SON & CO. 
1880. Entered according to Act of Congress, in the year 1880, by 
HENRY C. LEA, 
in the Office of the Librarian of Congress. All rights reserved. 
COLLINS, PRINTER. PREFACE. 
As a rule, the occupation of a practising physician 
precludes the possibility of his being a chemist; and the 
errors which have crept into the history of physiological 
chemistry through hasty conclusions from imperfectly 
performed work, are sufficiently numerous to demon- 
strate that chemical research can only be undertaken by 
one whose time may be wholly devoted to the subject. 
The chemistry of life is as yet in a rudimentary condi- 
tion : with few exceptions, it consists of a mass of un- 
connected facts, more or less developed as the interest of 
the experimenter has been arrested. 
Until the metamorphoses of the proximate principles 
of organized matter can be accomplished in the labora- 
tory in a manner which may be comparable to their 
transformations in the body, zoochemistry cannot take 
the position of an exact science. The results of recent 
studies on the more obscure fermentations have indicated 
that these phenomena may have an important bearing on 
biological chemistry ; and the synthesis of complex com- 
pounds closely related to the albuminoid bodies, serves IV 
PREFACE. 
to show that we may hope for a better understanding of 
the vital functions at a not very distant day. 
But -while biological chemistry is unsatisfactory as a 
science, an acquaintance with those compounds which 
normally form part of our tissues, the variations which 
these compounds undergo in altered conditions of the 
health, and an ability to detect substances which are 
themselves the evidence of pathological action, are often 
of incalculable service to the physician, in confirming or 
guiding diagnosis, and consequently in selecting treat- 
ment. 
At one time, Bowman’s little book on Medical Chem- 
istry supplied the practical information required by 
physicians in the application of chemistry to clinical 
research ; but Bowman’s Medical Chemistry has long 
been out of print, and newer and better methods have 
arisen with the development of chemistry ; at the same 
time, no suitable text-book embracing these methods has 
appeared in English. 
While, therefore, it has not been deemed advisable to 
follow the general plan of the former work, a plan which 
at the present day is open to many serious objections, 
this little book is designed to fill the place so well filled 
by the other before its time of usefulness had passed. 
The only two works on zoochemical analysis which 
have any claim to a scientific basis, are those of Gorup- 
Besanez, and of Hoppe-Seyler. On these, this book has 
in part been modelled, and it is believed that the arrange- 
ment will be found acceptable and convenient. The matter PKEFACE. 
Y 
is presented in as few words as. possible for its clear ex- 
planation, and the discussion of doubtful chemical ques- 
tions, always perplexing except to professional chemists, 
as well as the description of processes which cannot be 
recommended, are as a rule entirely omitted, as are also 
those crude methods of approximate estimation which 
amount to little more than conjectures, and are entirely 
untrustworthy. 
The first part of the book is devoted to a brief descrip- 
tion of the proximate principles which take part in nor- 
mal and pathological vital action, and the properties by 
which they may be separated from their associate com- 
pounds, and identified. 
In the second part, the composition of the more im- 
portant liquids and solids of the body is considered, to- 
gether with the processes by which they may be analyzed, 
both for the estimation of their normal constituents, and 
for the detection of compounds whose presence must be 
regarded as pathological. The methods given in this 
part have been carefully selected as those which will 
yield the most accurate results in hands not specially 
skilled in chemical manipulations. All of these opera- 
tions require practice and great care if any degree of 
accuracy be desired; without this, analysis can be of 
but little service. 
The third portion of the book treats of the detection 
of the more ordinary poisons. A toxicological investi- 
gation is seldom undertaken by a physician, but cases 
may sometimes arise in which a comparatively easy pre- vi 
PREFACE. 
liminary examination may indicate either the importance 
of a subsequent analysis by an expert chemist, or that 
suspicions of poisoning had been groundless. The direc- 
tions here given will he found sufficient in such cases. 
This is the only part of the work which is modelled on 
the plan of Bowman’s Chemistry. 
WM. H. GREENE. 
University op Pennsylvania, 
1st March, 1880. CONTENTS. 
INTRODUCTION 13 
Manipulation. Solution, extraction, filtration, dialysis. 
Evaporation, desiccation, incineration . . 13—16 
PAGE 
PART I. 
ORGANIC PROXIMATE PRINCIPLES TAKING PART IN THE 
ANIMAL ECONOMY. 
Fatty acids 17 
Formic acid, acetic acid, propionic acid, butyric acid, 
valeric acid, caproic acid ..... 17—19 
Detection and separation of the fatty acids ... 19 
Lactic acid, paralactic acid, zinc lactate and paralactate, de- 
tection of lactic acid ....... 20 
Oxalic acid,—calcium oxalate ...... 22 
Succinic acid, detection in the urine 24 
Benzoic acid .......... 25 
Glucose, detection by Moore’s test, Trommer’s test, Fehling’s 
test, Bottger’s test ...... 27-- 9 
Inosite, separation from muscular juices and from urine, tests 
for inosite ......... 29 
Lactose, decomposition by acids ...... 30 
Glycogen, differences from starch ...... 31 
Cholesterin, extraction from biliary calculi .... 32 
Stercorin or serolin, excretin ...... 33 
Urea, action of acids and alkalies, chlorine, hypochlorites, 
hypobromites, mercuric nitrate. Extraction from 
urine .......... 34 
Urea nitrate, urea oxalate ...... 35-36 
Detection of urea ........ 37 
Hippuric acid, preparation from urine ..... 37 CONTENTS. 
Uric acid, detection by tlie murexide test,—extraction from 
small quantities of liquid ..... 39-41 
Xanthine, detection in urinary calculi ..... 42 
Hypoxanthine, compounds of silver nitrate with xanthine 
and hypoxanthine ....... 43 
Guanine . . . . . . . . .44 
Carnine, preparation from extract of meat .... 44 
Oxaluric acid, extraction from urine 45 
Creatine, preparation from flesh,—decompositions . . 46 
Creatinine, its compound with zinc chloride,—detection in 
urine .......... 48 
Leucine, preparation and properties ..... 50 
Tyrosine, reactions by which it is distinguished from leucine 52 
Neurine or choline, extraction and properties ... 53 
Taurine, preparation from ox-gall ..... 54 
Glycocholic acid, Pettenkofer’s test for biliary acids . . 56 
Taurocholic acid, containing sulphur, is easily distinguished 
from glycocholic acid . . . . . . .57 
Cholic acid, a decomposition product of the two preceding 
acids .......... 58 
Lecithins, extraction from yolk of egg ..... 59 
Pkosphoglyceric acid . . . . . . . .59 
Cystine, detection in urinary calculi . . . . .60 
Albuminoid bodies, general properties, composition, behavior 
with reagents ........ 61 
Detection of an albuminoid body of undetermined nature . . 63 
Classification of albuminoid bodies ..... 64 
Albumen, nitric acid test, phenol test, metaphosphoric 
acid test,—egg albumen, estimation of albumen . 65—66 
Vitellin, globulin, hydropisin, pancreatin, paralbumen, metal- 
bumen .......... 67 
Hemoglobin, oxyhemoglobin, reduced hemoglobin, absorp- 
tion spectra ....... 68—70 
Hematin, hematin hydrochloride or hemin. Hematoidin . 70—71 
Fibrin, fibrinogen and fibrinoplasmin .... 71 
Myosin, preparation from muscles . . . .72 
Syntonin, preparation from various forms of albumen . 73 
Albuminose or peptones ....... 73 
Casein, alkaline albuminates ...... 74 
Animal ferments, ptyalin, pepsin, pancreatic ferments 74-76 
Substances resembling albuminoid bodies, general composi- 
tion ....... ... 76 
Ossein, gelatin, chondrin, keratin, mucin .... 77 
PAG E CONTENTS. 
IX 
PAGE 
Animal pigments, melanine 78 
Bilirubin, Gmelin’s test for biliary pigments, biliverdin, 
bilifuscin, biliprasin, extraction from bile and separation 79—81 
Hydrobilirubin, existence in febrile urine .... 82 
Indican, chemical properties, detection in urine . . 83 
Indigotine, identical with uroglaucin, urocyanin, etc. . 84 
Indirubin, extraction from violet urine .... 85 
PART II. 
Urine ........... 87 
Physical properties ....... 87 
Normal constituents ....... 88 
Abnormal constituents, accidental constituents . . 89 
Chemical examination, quantity, consistence, specific grav- 
ity, reaction, cause of normal acidity, alkaline urine, 
color 90-94 
Detection of abnormal substances— 
Albumen, nitric acid test ...... 94 
Glucose, application of Fehling’s test .... 95 
Inosite ......... 96 
Lactic acid, found after poisoning by phosphorus . 97 
Biliary acids and pigments, Pettenkofer’s test, Gmelin’s 
test, red hepatic urine, blue and violet urine . 97-100 
Cystine, urine smells of hydrogen sulphide . . 100 
Leucine and tyrosine, separation and detection . . 101 
Blood .......... 102 
Ammonia ......... 103 
Rapid qualitative analysis of urine ..... 103 
Quantitative analysis, estimation of normal constituents. 
Approximate composition .... 103-104 
Estimation of water and of fixed matters, method of 
Magnier de la Source, Neubauer’s approximate cal- 
culation ......... 105 
Organic constituents— 
Estimation of urea by Liebig’s method, preparation 
of the mercuric nitrate solution, corrections . 106-109 
Yvon’s method by sodium liypobromite . . . 110 
Esbach’s method ....... 113 
Estimation of uric acid ...... 114 
Estimation of hippuric acid ..... 115 
Estimation of creatinine . . . . . .116 
Mineral constituents— 
Sodium chloride, volumetrically by silver nitrate . 117 
Phosphoric acid, by uranium acetate . . . 119 
Sulphuric acid ; Vogel’s approximate method . . 121 
Abnormal constituents— 
Estimation of albumen ...... 122 
Estimation of glucose by Fehling’s solution . . 123 
Estimation of ammonia . . . ... . 125 
ANALYSIS OF SECRETIONS, EXCRETIONS, ETC. X 
CONTENTS. 
Urinary sediments, unorganized sediments, organized sedi- 
ments, extraneous matters ..... 125-134 
Urinary calculi, method of analysis,—uric acid calculi,— 
ammonium urate calculi,—xanthine,—cystine,—albu- 
minoid and epithelial matters,—calcium oxalate,—cal- 
cium and magnesium phosphates,—earthy carbonates, 
—mixed calculi ....... 134-139 
Blood, general physical properties,—normal chemical con- 
stituents,—abnormal constituents,—general chemical 
properties ........ 140-142 
Analysis of blood,—detection of urea,—uric acid,—creatine 
and creatinine, —glucose, — mineral salts, — biliary 
acids and pigments, — leucine and tyrosine, — ammo- 
nia,—carbon monoxide ..... 143-146 
Quantitative analysis, — average composition of human 
blood,—method of analysis, and calculation of re- 
sults,—estimation of water and of fixed matters,— 
mineral salts,—fibrin,—calculation of results . 146-153 
analysis of serum,—estimation of albumen, salts, etc., 
Hoppe-Seyler’s method,—estimation of hemoglobin,— 
anatomy of blood ....... 153 
Detection of blood spots and stains,—microscopical examina- 
tion,—detection of hemoglobin and of hematin by aid 
of the spectroscope,—detection by the production of 
hemin crystals,—confirmatory tests . . . 161-167 
Analysis of serous liquids 167 
Quantitative analysis . . . . . . .169 
Special serous effusions,—pleural effusions,—hydrocele,— 
expectorations after thoracentesis .... 170 
Pus, general properties,-—analysis,—blue pus, pyocyanin,— 
microscopic appearance of pus .... 172-174 
Extracts of the muscular tissues,—separation of creatine, 
fatty acids, lactic acid, inosite, uric acid,—Neubauer’s 
method 175-178 
Juices of glandular organs,—Staedler’s method of analysis 179 
Bone, teetii, and bony structures,—general chemical com- 
position,—quantitative analysis .... 181—186 
Saliva, — detection of potassium sulphocyanate,—ptyalin, 
salivary concretions ...... 187—189 
Gastric juice,—estimation of acidity and of hydrochloric 
acid 190-192 
Bile,—general properties ....... 193 
Analysis of biliary calcidi ....... 194 
PAGE CONTENTS. 
xi 
Milk.—General properties and composition,—analyses of 
cream.—Quantitative analysis of milk.—Millon and 
Commaille’s method.—Chevalier and Henry’s method. 
—Baumhauer’s method.—Volumetric estimation of 
lactose.—Rapid estimation of butter by the lacto-buty- 
rometer.—Lehmann’s method. — Various analyses 
of milk.—Milk of different animals . . . 196-208 
Examination of commercial milk,—detection of adultera- 
tions,—use of the lacto-densimeter .... 209 
Diseased milk . . . . . . . . .211 
Colostrum ......... 212 
Spermatic fluid,—detection of seminal stains . . . 214 
Excrements, general composition ...... 217 
Analysis of the ash of animal substances— 
Qualitative analysis ....... 219 
Quantitative analysis, — estimation of potassium and 
sodium, phosphate of iron, calcium, magnesium, sul- 
phuric acid, chlorine, phosphoric acid . . 223-225 
PAGE 
PART III. 
ON THE DETECTION OF POISONS. 
Precautions to be taken in chemico-legal investigations . 227 
Arsenic, usual forms in which it occurs .... 229 
Identification of pure arsenious oxide .... 230 
Detection in organic mixtures ...... 232 
Destruction of organic matter ..... 233 
Detection of cupro-arsenical pigments .... 235 
Reinsch’s test ......... 236 
Marsh’s test ......... 237 
Electrolytic test ........ 241 
Quantitative estimation 243 
Antimony, most common form tartar emetic,—reactions of 
tartar emetic,—tests for antimony .... 244 
Separation of antimony from arsenic, and quantitative 
estimation ......... 246 
Tin, differences from arsenic and antimony .... 247 
Mercury, separation from organic mixtures,—reactions of 
mercury,—electrolytic test, and quantitative estima- 
tion 248-252 
Lead, separation from organic mixtures,—examination of 
water suspected to contain lead,—quantitative esti- 
mation ........ 253-256 
Copper, reactions and quantitative estimation . . 257-260 
Zinc ........... 261 xii 
CONTENTS. 
Detection of acids, general method ..... 262 
Sulphuric acid,—sulphate of indigo ..... 264 
Hydrochloric acid,—quantitative estimation . . . 265 
Nitric acid ......... 266 
Detection of mineral acids in stains on clothing . . 267 
Oxalic acid ......... 268 
Hydrocyanic acid, detection in a state of vapor,—detection in 
solution,—quantitative estimation . . . 269—272 
Phosphorus, Mitscherlich’s method,—Fresenius’s method . 273 
Detection of alkaloids, Stas’s process,—general reagents 275-277 
Conine . . . . . . . . . .278 
Nicotine . . . . . . . . . . 279 
Morphine, Uslar and Erdmann’s process,—T. G. Worm- 
ley’s process,—chemical tests for morphine,—for me- 
conic acid ........ 280-284 
Opium alkaloids other than morphine .... 284 
Strychnine, Rodger and Girdwood’s process . . . 285 
Brucine, physiological tests ...... 287 
Detection of alcohol in organic mixtures .... 288 
Chemical examination for the detection of a poison the 
NATURE OF WHICH IS UNKNOWN ..... 289 
Volatile poisons,—alkaloids,—metallic poisons . 289-292 
PAUE 
APPENDIX. 
Volumetric analysis, normal solutions and standard solu- 
tions ......... 293-295 
Preparation of normal solutions, normal sodium carbonate, 
normal sulphuric acid, normal nitric acid, normal 
sodium hydrate ....... 295—296 
Estimation of carbonic acid gas, free and combined, in 
water .......... 297 
Estimation of ammonia . 299 
Estimation of combined acid in neutral salt . . . 299 
Standard solutions.—Objects attained by definite strength of 
standard solutions in analysis of urine,—solution of 
mercuric nitrate for estimation of urea,—silver solution 
for estimation of sodium chloride,—uranium solution 
for estimation of phosphates .... 300-302 
Weights and measures 303 MEDICAL CHEMISTRY. 
INTRODUCTION. 
Manipulation. 
§ 1. A familiarity with general chemical manipula- 
tion and the processes usually followed in analysis, is 
absolutely necessary to one who would study with profit 
the complex constituents, secretions, and excretions of 
the human body. 
The processes followed in physiological chemistry are 
essentially the same as those adopted in inorganic chem- 
istry, but the nature of the substance under examination 
frequently demands special modifications of these pro- 
cesses. Such methods of procedure will be indicated 
when considering their applications; it will be sufficient 
for tbe present to mention certain precautions necessary 
in the more ordinary operations of physiological analysis. 
Solution. Extraction. Filtration. Dialysis. 
The solution of a solid is always greatly facilitated by 
dividing the substance as finely as possible. If it be 
hard, it may be pulverized ; but soft substances, such as 
flesh, glandular structure, etc., must be cut up finely 
with a knife or scissors, and, if further division be neces- 
sary, it may be effected by trituration with coarsely 
powdered glass or quartz sand. 
Various solvents are employed, water, alcohol, ether, 
chloroform, benzol, acids, and alkalies, being used, accord- 
ing to the nature of the body under examination. One 14 
INTRODUCTION. 
or the other of these solvents often permits the separation 
of a body in a comparatively pure state from substances 
which may be soluble in other liquids. 
When the action of the liquid upon the substance is 
hut partial, and leaves certain substance undissolved, 
the process is called extraction. It is better to employ 
a small quantity of the solvent at a time, and when this 
is completely saturated to filter or decant the solution, 
treating the residue with a fresh portion of the solvent, 
and repeating the operation until all of the soluble matter 
is removed. 
It is frequently necessaiy to submit a substance to the 
successive action of several solvents. 
When rapid filtration is required, a folded filter may 
he used, hut when the precipitate or coagulum must be 
removed from the filter, the folds would frequently occa- 
sion a serious loss of substance. The filtration of many 
animal liquids is extremely slow and difficult, unless a 
filter-pump or aspirator be employed. 
Dialysis is frequently not only the most expeditious, 
hut the sole, method by which an uncrystallizable body 
may be separated from a bod}7 which will crystallize. A 
good dialyzer may he easily made by removing the 
bottom from a bottle, and replacing it by a sheet of parch- 
ment paper bound tightly over the edges. It should be 
suspended in a vessel of water so that the paper bottom 
does not touch the bottom of the vessel. If a solution 
of albumen or gum Arabic mixed with crystallizable salts 
be introduced into such a dialyzer, the salts will gradu- 
ally pass through the diaphragm, leaving the uncrystal- 
lizable substances in the bottle. The water in the ex- 
terior vessel should be frequently changed, and the 
dialysis is rendered much more rapid by occasionally 
agitating the fluid in the bottle. 
The evaporation of most animal liquids may be con- 
ducted on the water bath; there are but few organic 
substances of animal origin which are not destroyed or 
altered by a temperature above 100°. It is advanta- 
Evaporation. Desiccation. Incineration. INTRODUCTION. 
15 
geous that the capsule should be as flat as possible, and 
that its sides should be heated above the level of the 
liquid it contains: the creeping of the liquid on the sides 
of the dish may be thus avoided. 
Many substances will not support a temperature of 
100°; such must be evaporated in an air oven, or in a 
vacuum. 
The object of desiccation is to remove from substances, 
even when they appear quite dry, the hygroscopic water 
which they contain, and which is obstinately retained 
by animal matters. Without this desiccation, the results 
of analysis by weighing would be almost valueless. 
Desiccation is accomplished by the aid of a hot-air or 
water oven, or, in case the substance will not support a 
temperature of 100°, by exposing it for some time in a 
vacuum over either quicklime or strong sulphuric acid. 
Should the substance be not very hygroscopic, the hot- 
water or steam oven may be employed; as the interior 
temperature of a hot-water 
oven generally falls several 
degrees below 100°, it is 
advisable to add a consider- 
able proportion of glycerin 
to the water; by this means 
the temperature may be 
maintained at 100°, and as 
the glycerin does not vola- 
tilize with the water, it 
serves continually as the 
water is replaced. 
However, when the sub- 
stance is not decomposed by 
a temperature a few degrees 
above 100°, much more 
satisfactory results are ob- 
tained, and time is econo- 
mized, by exposing it to a 
temperature of 105-110° 
in a hot-air oven. 
After a substance has been dried, it must be placed 
over a dish containing sulphuric acid or quicklime, and 
Fig. 1. INTRODUCTION. 
covered at once with a bell jar (Fig. 1), and so allowed 
to cool before weighing. Any other suitable form of 
desiccator may be used. 
Incineration.—In order to determine the amount of 
inorganic salts contained in an animal product, it is neces- 
sary to incinerate the substance at a bright red heat until 
the whole of the carbon is burned out. Great care is 
required in the incineration of animal matters, as they 
usually increase enormously in volume when first heated, 
and frequently soften, so that there is danger that portions 
may be projected from the dish or crucible. The heat 
must, therefore, be applied slowly and cautiously until 
the matter is thoroughly carbonized: -when this is accom- 
plished there is no further danger, and the temperature 
may be raised and maintained until the incineration is 
complete, as is indicated by the white or very pale color 
of the ash. 
The burning of animal matters generally produces 
most offensive gaseous products, so that incinerations 
should be performed under a hood connected with a good 
chimney. PART I. 
ORGANIC PROXIMATE PRINCIPLES TAKING PART 
IN THE ANIMAL ECONOMY. 
Fatty Acids. 
§ 2. The organic acids which may be extracted from 
the tissues, secretions, and excretions, do not, as a rule, 
exist there in the free state, but in the form of salts, 
either of the alkaline or earthy metals, or of organic 
radicals, in the latter case constituting organic ethers. 
Of the fatty acids constituting the series C"II2a02, the 
first members up to the term C10II20O2 (capric acid) have 
been found in the secretions of the skin and in the liquids 
of certain glands. All of these acids are liquid at ordi- 
nary temperatures, and volatile; they have peculiar 
penetrating odors; they are soluble in water, alcohol, 
and ether, but their solubility in water diminishes as 
their proportion of carbon increases, and in the same 
order their boiling-points are higher. They are all 
strongly acid, and with the bases form salts which are 
generally soluble and crystallizable. 
The higher members of the series, palmitic and stearic 
acids, exist as glycerides in the animal fats. They are 
odorless and tasteless; solid at ordinary temperatures, 
and insoluble in water. 
§ 3. Formic acid,CH202.—Salts of this acid are found 
in the sweat, and in the liquids of the spleen and pan- 
creas, in the juices of the muscular tissues and the brain. 
Traces of it have been found in the urine. 
It may be distinguished from all other acids of the 
series by its pungent odor, and by its reducing silver 
nitrate to metallic silver by the aid of heat. It likewise 18 
ORGANIC PROXIMATE PRINCIPLES. 
reduces mercuric oxide when boiled with that compound. 
The alkaline formates are very soluble in water, and the 
other formates all more or less soluble. Ferric chloride 
produces a blood-red color in solutions of the neutral 
formates, and on boiling the liquid a yellow basic salt is 
precipitated. , . t 
§ 4. Acetic acid, C2TI402.—Acetic acid has been de- 
tected in the liquids of various organs, in the sweat and 
bile, and in the blood of lepers. It sometimes exists in 
the free state in the matters vomited by children, being 
formed by fermentation of farinaceous matters in the 
stomach. 
Its characteristic odor is well known; like formic 
acid, it dissolves in water in all proportions, hut unlike 
that acid, it is not decomposed when heated with con- 
centrated sulphuric acid. Silver nitrate produces a Avhite 
precipitate in strong solutions of the acetates; this pre- 
cipitate of silver acetate dissolves in warm water, but 
separates in crystalline needles on cooling. Silver nitrate 
is not reduced by boiling with acetic acid. With ferric 
chloride, the acetates produce a red color, analogous to that 
yielded under the same circumstances by the formates. 
Silver acetate contains 64.67 per cent, of silver. 
§ 5. Propionic acid, C3H602.—Propionic acid has 
been detected in the sweat and bile, and sometimes in 
the contents of the stomach. It has a penetrating odor, 
recalling at the same time that of acetic and that of 
butyric acids. It is quite soluble in water, but if calcium 
chloride be added to its solution, the acid separates, and 
floats on the surface of the liquid. 
The propionates much resemble the acetates. Silver 
propionate contains 59.67 per cent, of silver. 
§ 6. Butyric acid, C4H802.—This acid exists in a 
free state in the perspiration, and sometimes in the con- 
tents of the stomach and in the urine. Butyrates are 
found in the muscular liquids, and in the fluids of certain 
glands. } 
Its odor recalls that of rancid butter, in which it was 
first discovered. It is soluble in all proportions of water, 
alcohol, and ether, but calcium chloride separates it from 
its aqueous solutions. FATTY ACIDS. 
19 
The alkaline butyrates are deliquescent, difficult to 
crystallize, and not very stable. 
Silver butyrate is yellowish-white, crystalline, and 
almost insoluble in water. It contains 55.38 per cent, 
of silver. 
§ 7. Valeric acid, C5II10O2.—Valeric acid exists in 
solid human excrements; it is also found in the urine in 
typhus fever, and in cases of acute atrophy of the liver, 
this being explained by the fact that the decomposition 
of leucine (see § 60) yields ammonium valerate abund- 
antly. 
It is a colorless, oily liquid, having an unpleasant, 
penetrating odor, and a burning taste. It is soluble in 
all proportions of alcohol and ether, but requires 80 
parts of water for its solution. 
Its alkaline salts are soluble in water, and crystallize 
with difficulty; they all possess the odor and taste of 
valeric acid. 
Silver valerate contains 51.67 per cent, of metallic 
silver. 
§ 8. Caproic acid, C6II1202, exists in the excrements, 
and probably in the perspiration, as do also caprylic 
acid C8I11602, and capric acid C10II20 O2. The first 
two are liquid at ordinary temperatures, the latter is 
solid. All are difficultly soluble in water, easily soluble 
in alcohol, and have unpleasant odors, recalling that of 
the perspiration. 
DETECTION AND SEPARATION OF TIIE FATTY ACIDS. 
§ 9. The separation of the preceding acids is usually 
difficult in animal chemistry, because of the comparatively 
small amount of material which can be operated on. If 
the acids are to be sought in urine or perspiration, the 
liquid is distilled, almost to dryness, with dilute sulphuric 
acid, and the fatty acids are sought in the distillate. If 
the liquid to be examined be serous, it is first freed from 
albumen and the coloring matter of the blood, and then 
distilled with dilute sulphuric acid as before. 
The distillate in either case is saturated with potassium 
carbonate, evaporated to dryness, and again distilled 20 
ORGANIC PROXIMATE PRINCIPLES. 
with sulphuric acid. The liquid in the receiver will 
separate into two layers. The upper, oily layer con- 
tains the slightly soluble acids, from valeric to capric in- 
cluded. It is decanted, neutralized with baryta-water, 
and set aside to crystallize. The barium salts separate 
in the following order: barium caprate in fine, micro- 
scopic prisms, containing 28.6 per cent, of barium; ba- 
rium caprylate in granules, containing 82.38 per cent, of 
barium ; barium caproate in prismatic crystals grouped in 
hemispherical masses, and containing 37.38 per cent, of 
barium; barium valerate in large plates, resembling 
cholesterin, and containing 40.41 per cent, of barium. 
These salts must be purified by repeated crystallizations, 
and their proportion of barium determined in order to 
recognize the acid. 
The aqueous layer, which may contain the lower mem- 
bers of the series, from butyric to formic included, is 
saturated with sodium carbonate, and evaporated to a 
syrupy consistence. If acetic acid be present, sodium 
acetate crystallizes out; the mother liquor is then again 
distilled with sulphuric acid, and the oily layer of the 
distillate is separated and again distilled alone ; the por- 
tion which passes between 120 and 140° is collected 
apart, neutralized with ammonia, precipitated by silver 
nitrate, and boiled until the precipitate is entirely dis- 
solved. Any formic acid present will be decomposed, 
producing a black deposit of silver; this is separated by 
filtration, and, on cooling, the solution will deposit crys- 
tals of silver propionate. That portion of the liquid 
which passes between 141 and 160° may contain butyric 
acid; it is collected apart, saturated with baryta-water, 
and allowed to crystallize. Barium butyrate, purified 
by recrystallization, contains 48.41 per cent, of barium. 
Lactic Acid. 
C3JI603. 
§ 10. There are two lactic acids found in the economy, 
both having the same composition and probably the same 
molecular structure. The one is formed by the fermen- 
tation of lactose and glucose in presence of alkalies, and LACTIC ACID. 
21 
is known as lactic acid of fermentation; it is found in 
variable and uncertain quantities in the contents of the 
stomach and in the intestinal canal, resulting probably 
from the fermentation of certain articles of food. The 
other acid, called paralactic or sarcolactic, exists normally 
in the muscular juices, possibly in the gastric juice, and 
has been detected as a pathological constituent of the urine 
after poisoning by phosphorus. Although much labor 
has been devoted to the study of these acids, the question 
of their isomerism is by no means certainly decided; it 
seems to be a case of physical isomerism, and the acids 
differ more in their salt-forming powers than in their 
chemical properties. Paralactic acid is optically active, 
rotating the plane of polarized light towards the right. 
A third isomeride, hydracrylic acid, may perhaps ex- 
ist in the muscular juices, together with paralactic acid, 
but the matter is involved in doubt. 
§ 11. Lactic acid of fermentation may be prepared 
by allowing a mixture of 3 kilos of glucose dissolved 
in 13 litres of water, 4 kilos of sour milk, 100 grammes 
of old cheese, and 1.5 kilo of chalk to ferment for a 
week at a temperature of about 35°. The calcium lac- 
tate formed is recrystallized, decomposed by sulphuric 
acid, and the filtered liquid boiled, and saturated with 
zinc hydrocarbonate. After the crystallization of the 
zinc lactate, it is dissolved, decomposed by hydrogen 
sulphide, and the filtered liquid is concentrated on a 
water-bath. The acid is a syrupy, colorless liquid, which 
is altered and finally decomposed by heat. 
§ 12. Paralactic acid maybe prepared from extract of 
meat: this is extracted with weak alcohol, the alcohol 
distilled off, and the liquid residue acidulated with sul- 
phuric acid, and agitated with ether. The ether, being 
separated by distillation, leaves impure paralactic acid 
which is converted into zinc salt, and the latter is puri- 
fied by repeated crystallization, and decomposed by 
hydrogen sulphide. 
Paralactic acid much resembles its isomeride, already 
considered. By oxidation, both acids yield acetic and 
formic acids. 
§ 13. Zinc lactate, Zn(C3H503)2 4- 3H20, contains 22 
ORGANIC PROXIMATE PRINCIPLES. 
18.18 per cent, of water of crystallization, and is but 
slightly soluble in water; it separates from boiling 
aqueous solutions in crystalline needles or prisms, often 
grouped in tufts. It is almost entirely insoluble in 
alcohol. 
Zinc paralactate, Zn(C3II503)2 -f 2H20, contains 
12.90 per cent, of water of crystallization, and is much 
more soluble in water than the corresponding salt of 
ordinary lactic acid. It also dissolves freely in alcohol. 
The differences in the solubilities and percentage of 
water of crystallization of these two salts is sufficient to 
enable the distinction of lactic from paralactic acid. 
§ 14. If it be desired to test for lactic acid in urine, 
the latter is evaporated to dryness on a water-bath, and 
the residue is extracted with an alcoholic solution of 
oxalic acid; the filtered solution is then digested with 
lead oxide, again filtered, and the filtrate decomposed by 
hydrogen sulphide. After evaporation, the liquid sepa- 
rated from the precipitated lead sulphide, leaves any 
lactic acid present, and the latter is converted into zinc 
salt by boiling with zinc oxide. The zinc lactate or 
paralactate is recognized by the characters mentioned 
in the preceding section. 
C2H204 + 21FO. 
Oxalic Acid. 
§ 15. Free oxalic acid does not exist in the animal 
economy; it is found only as calcium oxalate, principally 
in urinary sediments and calculi. It is very frequently 
found in human urine, particularly after the ingestion 
of certain vegetable aliments, and after the internal use 
of alkaline acid-carbonates. 
It crystallizes in large, transparent, oblique-rhombic 
prisms, containing two molecules of water of crystalliza- 
tion. It melts in its water of crystallization at 98°, and 
becomes anhydrous at 100° ; at 132° it begins to decom- 
pose, and at about 155° breaks up into water, carbon 
monoxide, carbon dioxide, and formic acid. It is soluble 
in about 16 parts of water, and dissolves also in alcohol. 
All of the oxalates are decomposed by a red heat, OXALIC ACID. 
23 
disengaging carbon monoxide and carbon dioxide. The 
alkaline and earthy oxalates are then converted into car- 
bonates, while the other metallic oxalates leave a residue 
of oxide or of metal. With the exception of the alkaline 
oxalates, these salts are only very slightly soluble in 
water, or entirely insoluble. 
Lime-water and soluble salts of calcium produce, in 
solutions of oxalic acid or alkaline oxalates, a white pre- 
cipitate of calcium oxalate, which dissolves in hydrochloric 
and nitric acids, but is insoluble in acetic acid. It is 
also very soluble in sodium acid phosphate, and if this 
solution be neutralized, drop by drop, with a dilute solu- 
tion of sodium hydrate, the calcium oxalate separates in 
regular, characteristic crystals. 
When dry oxalic acid or an oxalate is heated with 
concentrated sulphuric acid, carbon monoxide and carbon 
dioxide are disengaged, and if the experiment be made 
with an appreciable quantity of the substance in a test- 
tube, the gas may be lighted at the mouth of the tube. 
§ 16. Calcium oxalate.—It is of importance to be able 
to recognize this salt, as it frequently occurs as a urinary 
sediment and a constituent of vesical 
calculi. Artificially prepared calcium 
oxalate occurs as a white powder, de- 
void of crystalline structure ; as has 
already been mentioned, it may be ob- 
tained crystallized by slowly precipi- 
tating it from its solution in sodium 
acid phosphate. It then presents the 
same appearance under the microscope 
as the crystals which are found in the 
urine. It forms characteristic, brilliant, 
and transparent, regular octahedra, 
somewhat resembling the reverse side 
of an envelop (Fig. 2). It is entirely 
insoluble in both hot and cold water, 
and in acetic acid, but dissolves in 
the strong mineral acids. When heated, 
it is converted into calcium carbonate, without carbon- 
ization. 
Fig. 2. 
Calcium oxalate. 
Calcium oxalate is identified by its crystalline form. ORGANIC PROXIMATE PRINCIPLES. 
It may possibly be held in solution by the sodium acid 
phosphate in very acid urine, but in this case it is pre- 
cipitated in crystals when the urine is gradually neutral- 
ized by sodium hydrate. 
It sometimes occurs in curious, dumb-bell shaped crys- 
tals, such as are represented in figure 3. When dry, 
Fig. 3. 
Fig. 4. 
Dumb-bell crystals of calcium oxalate. 
Dry calcium oxalate. 
the ordinary octahedral crystals appear opaque, with the 
exception of the centre which presents a brilliant square 
(Fig. 4); this appearance is caused by the high refrac- 
tive power of the crystals, and they may again be ren- 
dered transparent by moistening them with water. 
Succinic Acid. 
C4II604. 
§ 17. Succinic acid has been found in human urine, 
and in the perspiration and saliva, after the ingestion of 
benzoic acid. It is also found in the urine after the in- 
gestion of vegetables containing asparagin, and is pre- 
sent in the glandular juices, in the liquid contained in 
hydatid cysts, and in hydrocele. 
It crystallizes from its aqueous solution in brilliant 
rhomboidal plates, derived from a right-rhombic prism ; 
the angles of these plates are sometimes wanting, giving 
them the appearance of hexagonal tables (Fig. 5). It is 
colorless, odorless, and has a feeble, acid taste. It is 
very soluble in water, soluble in boiling alcohol, very 
slightly soluble in cold absolute alcohol and in ether. 
It melts at 180°, and boils at 285°, but if heated rap- 
idly it sublimes, giving off irritating vapors. It is quite BENZOIC ACID 
25 
stable, and is not attacked by nitric acid; when heated 
with potassium hydrate, it yields potassium oxalate. The 
alkaline succinates are freely soluble in water, but in- 
soluble in absolute alcohol. 
Fig. 5. 
Succiuic acid. 
According to Meissner, succinic acid may be detected 
in the urine as follows: Baryta-water is added to the 
urine as long as a precipitate forms; the mixture is fil- 
tered; the filtrate is exactly neutralized with sulphuric 
acid, and the barium sulphate formed is separated by 
filtration. The new filtrate is evaporated, so that the 
urates and urea may crystallize out, and the clear liquid 
is then dilated with absolute alcohol until its bulk is 
about equal to that of the urine employed. The deposit 
formed is exhausted with a little water, and the aqueous 
solution of sodium succinate so obtained is allowed to 
crystallize. When the crystals are treated with sulphuric 
acid, succinic acid is set free, and may be recognized by 
its crystalline form, its fusing point, and its stability when 
heated. 
Benzoic Acid. 
C7H602. 
§ 18. Benzoic acid is sometimes present in urine, be- 
ing a product of the decomposition of hippuric acid, or 26 
ORGANIC PROXIMATE PRINCIPLES. 
derived from the ingestion of a large dose of the acid. 
By sublimation, it crystallizes in long flexible needles; 
but when deposited from its aqueous solution, it crystal- 
lizes in rectangular tables, easily recognized under the 
microscope (Fig. 6). 
Fig. 6. 
Benzoic acid. 
For its detection in the urine or other animal fluid, 
the latter is rendered alkaline by sodium carbonate, and 
evaporated to dryness on a water-bath. The residue is 
exhausted with alcohol, and the alkaline solution treated 
with a little hydrochloric acid. Should no crystals of 
benzoic acid separate, the matter is exhausted with 
ether, and the solution is either left to spontaneous eva- 
poration, or mixed with water, which will cause the ben- 
zoic acid to separate in the crystallized state. Better 
crystals are obtained by allowing the ethereal extract to 
evaporate until it becomes thick and oily, and then treat- 
ing it with water. Once obtained, no difficulty will be 
experienced in identifying the acid. 
If a little benzoic acid be mixed with a small quantity 
of nitric acid, and the mixture be boiled in a porcelain 
capsule, as the residue becomes concentrated, a strong 
odor of nitrobenzol, resembling that of oil of bitter 
almonds, is developed. GLUCOSE. 
27 
Glucose. 
C61I1206. 
§ 19. Glucose exists normally in the blood, especially 
in that of the hepatic vein, in the lymph, the fluids of the 
liver, and in the chyle and contents of the small intestine 
after the ingestion of starchy or saccharine substances. 
Its normal occurrence in urine is doubtful, hut it is often 
found in large quantities in that liquid in certain patho- 
logical conditions, especially in diabetes mellitus. 
Pure glucose is a white solid, occurring in small crys- 
talline, cauliflower-like masses containing one molecule 
of water of crystallization. It melts when heated, loses 
its water of crystallization at 100°, and again solidifies. 
Anhydrous, it melts at 144°. It is soluble in a little 
more than its weight of cold water, and is much less 
soluble in alcohol. Its solutions rotate the plane of 
polarized light towards the right. 
§ 20. Detection.—Glucose is detected by the facility 
with which it reduces certain metallic salts, such as 
cupric salts, bismuth salts, etc., in alkaline solutions. 
The liquid to be tested should contain no albuminoid 
matter; if such be present, the liquid is treated with a 
few drops of acetic acid, boiled and filtered; or, if much 
albumen be present, as in the case of blood, the liquid is 
mixed with three or four times its volume of strong alco- 
hol, allowed to stand for some time, heated and filtered; 
the filtrate is evaporated to dryness on a water-bath, and 
the residue is exhausted with water. Or, again, the 
liquid may be rendered acid by acetic acid, saturated 
with crystallized sodium sulphate, heated to boiling, and 
filtered; by this method albumen and glucose may be suc- 
cessively sought for in the same liquid. 
§ 21. If a solution of glucose be made strongly alka- 
line with potassium or sodium hydrate and heated to 
boiling, the liquid assumes a yellow, brown, or black 
color, according to the proportion of glucose present 
(Moore). Traces of glucose give a yellow tint. 
§ 22. When a solution of glucose is mixed with potas- 
sium hydrate, and then agitated with a few drops of a 28 
ORGANIC PROXIMATE PRINCIPLES. 
dilute solution of cupric sulphate, no precipitate of cupric 
hydrate is formed, hut the liquid acquires a blue color. 
If now it be heated to boiling, a yellow or red precipitate 
of cuprous oxide is thrown down (Trommer). An ex- 
cess of cupric sulphate must be avoided, lest a black pre- 
cipitate of the cupric oxide in excess mask the color of 
the cuprous oxide. An excess of alkali is not detrimental, 
for if more glucose be present than is required to reduce 
the cupric oxide, the liquid above the precipitate becomes 
yellow or reddish-brown, as indicated in the preceding 
paragraph. 
§ 23. Much better results may be obtained by the use 
of Fehling’s solution, which is prepared as follows: 
34.64 grammes of pure, crystallized cupric sulphate are 
dissolved in about 200 c. c. of distilled water; 173 
grammes of sodium and potassium tartrate are dissolved 
in a solution of about 80 grammes of sodium hydrate in 
600 c. c. of distilled water; the solution so obtained is 
poured into the copper solution and the mixture agitated, 
and diluted with distilled water to exactly 1 litre. This 
liquid has a dark-blue color, and must be preserved in 
well-stoppered bottles in a cool, dark place. It is used 
also for quantitative estimations, and 1 c. c. of it is ex- 
actly precipitated by 5 milligrammes of glucose. 
In using this solution, about 5 c.c. are poured into a 
test-tube and heated to boiling. The liquid will remain 
clear if it be good. The suspected solution is then poured 
in, drop by drop, and, if glucose be present, the blue 
color will change to green, and almost immediately to 
yellow and red, cuprous oxide being precipitated. If 
only traces of glucose be present, it may be necessary to 
add several c. c. of the suspected solution, and to boil 
the mixture during one or two minutes. 
§ 24. Glucose reduces alkaline solutions of bismuth 
oxide at the temperature of ebullition, precipitating me- 
tallic bismuth (Bottger). The reagent may be prepared 
by moistening a mixture of 5 grammes of bismuth basic 
nitrate and 5 grammes of pulverized tartaric acid with 
about 30 c. c. of distilled water, and carefully adding, 
with continual agitation, strong solution of sodium hydrate 
until the whole is dissolved. The reagent does not keep INOSITE. 
well, and must be preserved in well-stoppered bottles. If 
some of this solution be boiled with a liquid containing 
glucose, a brown or black pulverulent precipitate of me- 
tallic bismuth will be formed. It is essential that the 
suspected solution be free from albumen, as the sulphur 
in the latter body would occasion a black precipitate of 
bismuth sulphide. 
Under the influence of yeast, glucose rapidly under- 
goes fermentation, yielding alcohol and carbon dioxide. 
Inosite. 
C6II1206 + IPO. 
§ 25. Inosite is present in small quantity in the mus- 
cular tissue of the heart, in the liver, lungs, pancreas, 
spleen, and kidneys. Pathologically, it is sometimes 
found in the urine of individuals suffering from diabetes 
or Bright’s disease, and in the muscles of habitual 
drunkards. 
It may be extracted from the juices obtained by expres- 
sion from the muscles, glandular tissues, lungs, etc. The 
albumen is coagulated by heat, the phosphates are pre- 
cipitated by addition of baryta -water, and the mixture 
is filtered ; the filtrate is concentrated, and, after the 
creatine has crystallized out and been separated, the 
aqueous liquid is mixed with several times its volume of 
hot, strong alcohol. If the precipitate formed be abun- 
dant and adhere to the vessel, the alcohol is decanted; 
but, if it be not viscous, the mixture is filtered boiling, 
and the filtrate allowed to stand 24 hours. The crystals 
of inosite that separate are collected on a filter and 
washed with a little cold alcohol. They are then redis- 
solved in a little boiling water, and the hot solution is 
mixed with several times its volume of strong alcohol and 
allowed to cool slowly ; the inosite then separates in 
delicate crystals. If in either of these operations the 
addition of alcohol occasion no precipitate, the solution 
is agitated with ether until it becomes turbid, and then 
allowed to stand (Boedecker). 
§ 26. Inosite may also be separated by precipitating 
the phosphates, albumen, etc., by a solution of neutral ORGANIC PROXIMATE PRINCIPLES. 
lead acetate, then filtering, and adding basic lead acetate, 
which precipitates inosite. The precipitate is washed, 
suspended in water, and decomposed by hydrogen sul- 
phide ; the filtered solution is then concentrated and 
precipitated by hot, strong alcohol, as directed in the 
preceding paragraph. This method is applicable to urine 
suspected to contain inosite. 
§ 27. Inosite crystallizes from its aqueous solutions in 
large oblique-rhombic prisms or tables, containing one 
molecule of water, which they lose in dry air. The 
small crystals are usually grouped in tufts. It is quite 
soluble in water, and the solution has a sweet taste. It 
is optically inactive, will not reduce Fehling’s solution, 
and will not ferment under the influence of yeast. 
§ 28. If a small quantity of inosite be moistened with 
nitric acid, on a piece of platinum foil, and evaporated 
nearly to dryness, the residue will acquire a bright rose- 
red color Avhen treated with a drop of ammonia and a 
little calcium chloride, and again carefully evaporated to 
dryness. This test is very delicate, but succeeds only 
with pure inosite (Scherer). These reactions serve to 
distinguish between inosite and glucose. 
C12H22On + IPO. 
Lactose. 
§ 29. Lactose exists in the milk of all herbivorous 
mammals, in woman’s milk, and in that of the dog. It 
probably exists also in the milk of all mammals. 
It is prepared by evaporation of the whey which re- 
mains after the manufacture of cheese, the crystals 
which separate being subjected to several recrystalliza- 
tions. It occurs in colorless right-rhombic prisms, ter- 
minated by octahedral pyramids, and containing one 
molecule of water, which they lose at about 140°. 
They are hard, and grate when crushed between the 
teeth. Lactose requires about 6 parts of cold or 2 parts 
of boiling water for its solution, and is insoluble in abso- 
lute alcohol. Its solutions are dextrogyrate. G LYCOGEN. 
31 
§ 30. Under the influence of dilute acids, lactose is 
converted into glucose, and an isomeric sugar which is 
known as galactose. The solution will then undergo 
the alcoholic fermentation. In presence of casein, alka- 
line solutions of lactose yield various fermentation pro- 
ducts, principally lactic acid, which is finally converted 
into butyric acid. 
Lactose reduces Fehling’s solution, even in the cold, 
but less readily than glucose, from which it may be dis- 
tinguished by its crystalline form and its much more 
difficult and imperfect fermentability under the influence 
of yeast. 
Glycogen. 
C6II10O5. 
§ 31. This compound, which is isomeric with the 
starches, A\as discovered by Bernard in the tissue of the 
liver, and afterwards in the placenta ; it exists also in 
nearly all the organs during foetal life. It may he ob- 
tained by macerating finely divided liver, previously de- 
prived of its blood, with water, acidifying the opalescent 
decoction with acetic acid, heating to boiling, and sepa- 
rating the coagulum by filtration. The filtrate is mixed 
with twice its volume of strong alcohol, and, after stand- 
ing for several hours, is again filtered. The precipitate 
on the filter is washed with alcohol, dissolved in water, 
and again treated with a little acetic acid, boiled and 
filtered, and the clear liquid precipitated by alcohol. 
The precipitate, consisting of pure glycogen, is collected 
on a filter and washed with a little ether. 
§ 32. So obtained, glycogen is a snow-white, amor- 
phous powder. When dried at low temperatures, it con- 
tains one molecule of water, hut becomes anhydrous at 
100°. It swells in cold water, and quickly dissolves by 
the aid of heat, forming an opalescent liquid which be- 
comes clear on the addition of potassium hydrate. It is 
insoluble in alcohol and ether; its aqueous solution is 
dextrogyrate. 
Boiling with dilute acids converts it into glucose, and 32 
ORGANIC PROXIMATE PRINCIPLES. 
the same change is brought about by the action of saliva, 
pancreatic juice, diastase, and other ferments. Iodine, 
employed in small quantity, colors it brown, dark red, 
or even violet; but the tint can readily be distinguished 
from the blue color produced by that reagent with starch. 
Glycogen may also be distinguished from the latter body 
by its amorphous appearance under the microscope. 
Cholesterin. 
C26fl440. 
§ 33. This compound is wid.ly distributed in the 
human body. It exists in the brain and nerve tissues, 
the serum of blood, yolk of egg, bile, and excrements. 
It is the principal constituent of most biliary calculi, and 
also occurs pathologically in pus and in dropsical effu- 
sions, especially in ovarian dropsy and in hydrocele. 
Cholesterin may be easily extracted in a pure state 
from biliary calculi. These are crushed, exhausted with 
boiling water to remove pigments arid mineral salts, and 
Fig. 7. 
Cholesterin. 
the dry residue is boiled with alcohol. The alcoholic 
solution is filtered while hoc, and the cholesterin crystal- 
lizes out on cooling. It may be purified by recrystal- CIIOLESTERTN. 
33 
lization in alcohol or ether. It is readily soluble in ether 
and in hot alcohol, from which it separates on cooling in 
thin, brilliant, transparent, and colorless rhombic plates, 
of which the edges are generally broken and somewhat 
irregular (Fig. 7). It is also soluble in benzol and in 
chloroform, but entirely insoluble in water. 
It is tasteless and odorless, somewhat greasy to the 
touch. It melts at 145°, and may be sublimed, out of 
contact with air, at 360°. Its solutions are neutral, and 
deviate the plane of polarized light towards the left. 
If cholesterin be moistened with concentrated sulphuric 
acid, triturated, and then agitated with chloroform, a 
blood-red or violet solution is obtained, which gradually 
becomes colorless on contact with the air, passing suc- 
cessively through the tints of violet, blue, and green. 
The appearance of thin transparent plates in an animal 
liquid, under microscopic examination, would indicate 
the probable presence of cholesterin; the latter may be 
then extracted by treatment with ether, but its separation 
from fatty and soapy matters is often exceedingly difficult. 
STERCORIN AND SEROLIN. 
§ 34. When dried serum of blood is treated with a 
large quantity of boiling alcohol, and the liquid filtered, 
white pearly scales are deposited on cooling. This sub- 
stance was named serolin by Boudet. Flint subsequently 
obtained it in considerable quantity from the excrements, 
and named it stercorin. It melts at 36°, dissolves 
readily in ether, but not so well in cold alcohol, and is 
neutral to litmus-paper. It is colored red by concen- 
trated sulphuric acid, like cholesterin. Hoppe-Seyler 
regards it as a mixture of cholesterin, lecithine, etc. ; 
derived from the blood. 
EXCRETIN. 
§ 35. This compound was obtained by Marcet from 
human excrements. The latter are exhausted with boil- 
ing alcohol, and the cold filtered extract is precipitated 
by calcium hydrate ; the precipitate is dried and treated 34 
ORGANIC PROXIMATE PRINCIPLES. 
with hot alcohol and ether ; after a few days, these so- 
lutions deposit excretin in prismatic crystals, which are 
insoluble in water, almost insoluble in cold alcohol, but 
readily soluble in hot alcohol and in ether. It melts at 
92-96°, and is unattacked by boiling alkaline and acid 
solutions, excepting nitric acid. It contains sulphur. 
Urea. 
CON2!!4. 
§ 36. Urea is the principal solid constituent of human 
urine, the greater part of the nitrogen produced by the 
waste of the tissues being eliminated in this compound. 
It exists also in the blood, in the exudations, and in very 
small quantity in the aqueous humor and the lymph. 
When for any reason its elimination by the kidneys is 
arrested or interfered with, it accumulates in the liquids 
of the body, and may be detected in the perspiration and 
the saliva. 
Pure urea crystallizes in long, four-sided rhombic 
prisms, terminated by obtuse pyramids of which only 
one or two faces are developed. They are white, silky, 
and striated. They are anhydrous, and may be heated 
to 120° without decomposition ; above that temperature 
they melt, disengaging ammonia. 
Urea is soluble in about its own weight of cold water, 
and in the same quantity of boiling alcohol; almost in- 
soluble in ether. Its aqueous solution is neutral, but 
slowly decomposes after a time, more rapidly by the 
action of heat. 
§ 37. The strong mineral acids and the alkaline hy- 
drates decompose urea, with the formation of carbon di- 
oxide and ammonia. 
By the action of nitrous acid, it is converted into 
water, nitrogen, and carbon dioxide. 
§ 38. Chlorine and the alkaline hypochlorites decom- 
pose it, with formation of hydrochloric acid, water, and 
carbon dioxide, and liberation of nitrogen. Bromine and 
the alkaline hypobromites act in a similar manner. 
§ 39. If a solution of urea be mixed with a solution of 
mercuric nitrate, a precipitate is formed having a variable UREA 
35 
composition, being a mixture of compounds containing 
two molecules of urea nitrate combined Avith two, three, 
and four molecules of mercuric oxide. If a dilute solu- 
tion of mercuric nitrate be slowly added to a dilute solu- 
tion of urea, and the mixture be neutralized from time to 
time with sodium carbonate, a moment will arrive when 
the addition of the latter compound will communicate to 
the precipitate a yellow color, indicating the presence of 
free mercuric nitrate. The whole of the urea is then 
precipitated, and the precipitate contains two molecules 
of urea nitrate and four molecules of mercuric oxide 
(Liebig). 
These reactions are employed for the estimation of 
urea. 
§ 40. Urea may be extracted from urine by precipi- 
tating the phosphates and sulphates by a mixture of one 
volume of barium hydrate and two volumes of barium 
nitrate, both in saturated solution, filtering, evaporating 
the filtrate to dryness on a water-bath, and exhausting 
the residue with hot absolute alcohol. The alcoholic 
solution is allowed to crystallize, and if the product 
obtained be colored, it is redissolved in alcohol, filtered 
through animal charcoal, and again crystallized. 
UREA NITRATE. 
C0N2H4.IIN03. 
§ 41. Urea combines with a number of acids, forming 
well-marked crystalline compounds. The nitrate, which 
is characteristic, may be obtained by adding moderately 
strong nitric acid to a concentrated solution of urea, and 
cooling the mixture. The compound separates in brilliant 
white scales or plates, or in prismatic crystals. The 
forms of these crystals may be well studied by bringing 
in contact a drop of nitric acid and a small crystal of 
urea upon a glass slide on the stage of the microscope 
(Fig. 8). 36 
ORGANIC PROXIMATE PRINCIPLES 
Fig. 8. 
Urea nitrate. 
UREA OXALATE. 
(C0N2H4)2.C2II204. 
§ 42. This compound is obtained by mixing concen- 
trated solutions of urea and oxalic acid. The crystals 
are sometimes very similar to those of the nitrate, but 
Fig- 
Urea oxalate. 
generally present such great variations that they are by 
no means as characteristic and certain as those of the 
latter salt (Fig. 9). HIPPURIC ACID. 
37 
DETECTION OF UREA. 
§ 43. Urea is recognized by the crystalline forms of 
its nitrate and oxalate. If the liquid to be examined be 
tree from albumen, it is evaporated to dryness, exhausted 
with absolute alcohol, the solution evaporated, and the 
residue treated with pure nitric or oxalic acid on a micro- 
scope slide. If the liquid be serous, it is mixed with 
three or four times its volume of strong alcohol, which 
precipitates the albumen and a great part of the salts; 
it is then filtered and evaporated to dryness, and the 
residue extracted with absolute alcohol as before. Very 
small quantities of urea may be thus detected. 
Care must be taken not to confound the crystals of 
urea nitrate with those of an alkaline nitrate, which they 
resemble, and which might be obtained in the examina- 
tion for urea of blood or other serous liquid. The dis- 
tinction is easily made by heating the crystals on a piece 
of platinum foil or on the microscope slide. An alkaline 
nitrate will then fuse and leave a fixed white residue, 
while urea nitrate will completely volatilize, or leave a 
mere trace of residue in case the salt be not perfectly 
pure. 
Crystals of urea nitrate may be easily obtained from 
urine by evaporating the latter to about one-fifth its vol- 
ume, filtering, and adding about an equal quantity of 
somewhat dilute nitric acid (specific gravity 1.25). The 
liquid often solidifies to a crystalline mass. The crystals 
may be drained, redissolved in the smallest possible 
quantity of boiling water, and the solution decolorized 
by hot filtration through animal charcoal. On cooling, 
colorless crystals of urea nitrate will be deposited. 
Hippuric Acid. 
CHPNO3. 
§ 44. Hippuric acid exists in the urine of the horse 
and many other herbivorous animals, and in small quan- 
tity in human urine ; it is generally found as an alkaline 
salt or in combination with calcium. The proportion 38 
ORGANIC PROXIMATE PRINCIPLES. 
existing in human urine is much increased by an exclu- 
sively vegetable diet. 
Benzoic acid is converted into hippuric acid in the 
system, and the latter acid may be readily obtained from 
human urine by administering twenty-five or thirty 
grammes of benzoic acid in the evening, and treating the 
urine passed during the night and the following morning. 
This is mixed with milk of lime, and boiled for a few 
minutes ; the liquid is filtered hot, and the filtrate rapidly 
evaporated to one-sixth or one-eighth of its volume and 
saturated with hydrochloric acid. The hippuric acid 
which is precipitated is collected on a filter, again boiled 
with milk of lime, filtered, and the filtrate precipitated 
by hydrochloric acid. Should the acid still remain 
colored, it may be completely decolorized by dissolving 
it in boiling water, adding animal charcoal, and filtering 
while boiling. Putrid urine will not yield hippuric acid. 
§ 45. Hippuric acid crystallizes in long colorless 
prisms (Fig. 10), slightly soluble in cold water and in 
Fig. 10. 
Hippuric acid. 
ether; very soluble in boiling water and in alcohol. It 
is odorless, hut has a somewhat bitter taste. Its solu- 
tions strongly redden blue litmus. 
When hippuric acid is heated in a tube, it melts and URIC ACID. 
39 
yields a sublimate of benzoic acid; at the same time a 
small quantity of benzonitrile, an oily liquid having an 
unpleasant odor, distils and condenses in red, oily drops 
on the sides of the tube. 
If hippuric acid be boiled with concentrated nitric 
acid, and the mixture be evaporated to dryness and 
heated in a small tube, the characteristic odor of nitro- 
benzol will be perceptible. 
Uric Acid. 
C5lPiN403. 
§ 46. Uric acid is constantly present in normal human 
urine, and in that of carnivorous animals; it is also found 
in the urine of herbivores, but in much smaller quantity. 
It constitutes the entire mass of certain vesical calculi, 
and, either free or in combination, the gouty concretions 
sometimes formed in the joints. It exists in small 
quantity in human blood, and in large quantity in the 
excrements of birds and serpents, and in guano. The 
quantity excreted in the urine of a healthy adult varies 
from one to three or four decigrammes per day. 
The process indicated for its quantitative estimation 
(§ 151) serves for its preparation. 
Fig. 11. 
Uric acid. 
§ 47. Pure uric acid is a light, white powder, com- 
posed of microscopic crystals belonging to the right- 40 
ORGANIC PROXIMATE PRINCIPLES. 
rhombic system (Fig. 11). It is tasteless and odorless, 
and only slightly soluble in water. 1 part of uric acid 
requires from 11,000 to 15,000 parts of cold water, or 
from 1800 to 1900 parts of boiling water, to effect its 
solution. It is entirely insoluble in alcohol and ether. 
It is insoluble in hydrochloric acid, but dissolves readily 
in concentrated sulphuric acid from which it is again pre- 
cipitated by the addition of water. Its aqueous solutions 
are almost without action on litmus paper, even when 
saturated at the temperature of ebullition. 
§ 48. Solutions of the alkalies dissolve uric acid 
readily, forming neutral urates; uric acid is dibasic, and 
the acid urates are much less soluble than the neutral salts. 
Uric acid is not volatile; when heated in the air, it 
burns, leaving no residue. When heated in a tube, it 
blackens, disengages urea, hydrocyanic acid, oily pyro- 
genous products, and some cyanuric acid which condenses 
in crystals on the sides of the tube. The residue is a 
nitrogenized carbon. 
§ 49. Uric acid dissolves in moderately strong nitric 
acid, wTith decomposition and the formation of a yellow 
solution; nitrogen and carbon dioxide are disengaged, 
and the residue consists of alloxane* and urea. If this 
solution be cautiously evaporated to dryness, the resi- 
due assumes a red color, and if it be moistened with very 
dilute ammonia, a rich purple color will be developed. 
The names murexide and ammonium pur pur ate have been 
given to the purple compound so formed. If the ammo- 
nia be replaced by a solution of potassium hydrate, a 
blue color will be obtained. 
Caffeine gives a similar color with nitric acid, and the 
residue becomes purple when moistened Avith ammonia, 
but potassium hydrate produces no effect. 
Solutions of the alkaline urates reduce Fehling’s solu- 
tion, precipitating Cu20. 
§ 50. Uric acid is detected by the murexide test, and 
by its crystalline form as shown by the aid of a micro- 
scope. 
* C4H2N204. This body was found by Liebig in the mucus of an 
intestinal catarrh. This is probably the only certain instance of 
its detection in the body. URIC ACID. 
41 
The murexide test is conveniently made in a watch- 
glass or small porcelain capsule, in which the substance 
suspected to contain uric acid is placed, and, if liquid, 
evaporated to dryness. It is then moistened wTith nitric 
acid and gently heated over a flame or on a water-bath. 
If much uric acid be present, a considerable effervescence 
takes place: this terminated, the residue is cautiously 
evaporated to dryness, the capsule being moved so as to 
spread the liquid over its surface. The residue, which 
was at first pale-yellow, gradually becomes bright-red as 
the excess of acid is expelled. The red color is a proof 
of the presence of uric acid, but the residue should be 
moistened with a drop of ammonia, or better, a glass rod 
bearing a drop of ammonia may be held near the residue 
until the fumes produce the required effect. Under 
these circumstances, the presence of uric acid is indicated 
by a rich purple color. 
§ 51. If it he desired to extract the uric acid from a 
small quantity of a liquid, such as urine, the latter, of 
EXTRACTION FROM SMALL QUANTITIES OF LIQUID. 
Fig. 12. 
Uric acid precipitated by hydrochloric acid 
which at least 5 or 6 c.c. should he used, is placed in a 
large watch-glass, and five or six drops of concentrated 
hydrochloric acid are added. A linen thread is intro- 
duced into the mixture, and the glass is covered and set 42 
ORGANIC PROXIMATE PRINCIPLES. 
aside for twenty-four hours in a cool place. The uric 
acid sloAvly crystallizes on the thread, and may be ex- 
amined by the aid of a microscope. When so precipitated 
by hydrochloric acid, the crystals usually present the 
forms shown in Fig. 12. 
Xanthin e. 
C5H4N402. 
§ 52. Xanthine is found in certain rare urinary cal- 
culi, and exists normally in the urine, liver, spleen, brain, 
and muscular tissues, only, however, in very small quan- 
tity. (See § 196.) 
It is a hard, pale-yellow substance, which assumes a 
wax-like appearance by friction. It is scarcely soluble 
in cold water, but dissolves in boiling water ; almost in- 
soluble in alcohol and ether. After the evaporation of 
its aqueous solution it is deposited in a leaf-like film. 
When heated, it decomposes without melting. 
It dissolves in nitric acid, by the aid of heat, without 
evolving gas, and the solution leaves a yellow residue 
after evaporation, which is colored reddish-yellow by 
potassium hydrate, and becomes reddish-violet when 
heated. 
Xanthine dissolves also in potassium hydrate, and in 
ammonia, and on the evapo- 
ration of its ammoniacal solu- 
tion is deposited in groups oi 
brilliant laminae. 
The detection of xanthine 
in urinary calculi is not dif- 
ficult, since xantliic calculi 
are composed almost entirely 
of that body. The calculus 
is dissolved in potassium hy- 
drate, the xanthine precipi- 
tated by hydrochloric acid, 
and characterized by its solubility in ammonia, its re- 
action with nitric acid and potassium hydrate, and by the 
fact that its nitric acid solution yields with silver nitrate 
a flocculent precipitate, which dissolves on boiling, and 
Fig. 13. 
Xanthine and silver nitrate. HYPOXANTHINE. 
43 
is again deposited in groups of microscopic needles on 
cooling (Fig. 13). 
For the extraction of xanthine from urine, 50 or 100 
litres of that liquid are necessary. 
Hypo xanthine (sarcine) 
C5H4N40. 
§ 53. Hypoxanthine exists in small quantity in the 
muscular tissues, spleen, liver, and in the marrow of the 
bones. Larger quantities are found in the liver when 
that organ is in the diseased condition known as acute 
yellow atrophy. 
It is only slightly soluble in cold water, more soluble 
in boiling water; not very soluble in alcohol. It forms 
microscopic, colorless needles, and is deposited on the 
cooling of its boiling aqueous solution, in white flakes. 
It much resembles xanthine, from which it can only be 
separated with difficulty. (See § 196.) 
It is decomposed when heated above 150°. It dissolves 
easily and without decomposition in ammonia and in alka- 
line or slightly acid solutions. The residue left by the 
evaporation of its nitric acid solution is not affected by 
potassium hydrate, unless heat be applied. 
Fig. 34. 
If ammoniacal silver nitrate be added to an ammoniacal 
solution of hypoxanthine, a double compound of silver 
and hypoxanthine nitrates separates as a colorless, gela- 
tinous precipitate; this is insoluble in water and in am- 
monia, but dissolves somewhat in boiling nitric acid. If 
Hypoxanthine and silver nitrate. 44 
ORGANIC PROXIMATE PRINCIPLES. 
this solution be allowed to cool very slowly and evaporate 
in a watch-glass, large prismatic crystals are obtained, 
often grouped in stars (Fig. 14). The compound of 
xanthine and silver nitrate is much more soluble in nitric 
acid, and separates from its solutions very slowly, some- 
times only after the lapse of several days. 
§ 54. By the action of reducing agents, such as fer- 
rous sulphate, hypoxanthine is converted into guanine, 
C5H5N50, a body which was first obtained from guano, 
but has since been found in the pancreas and in the liver. 
It is a yellowish-white solid, tasteless, and odorless, in- 
soluble in water, alcohol, and ether, but soluble in acids 
and in solutions of the alkaline hydrates. 
GUANINE. 
Carnine. 
C7H8^403. 
§ 55. This compound was discovered by Weidel in 
commercial extract of meat. He prepared it by dissolv- 
ing the extract in five or six times its weight of warm 
water, and adding saturated baryta-water to the solution 
as long as a filtrate was formed, at the same time avoid- 
ing an excess of baryta. When the clear liquid obtained 
by filtering this mixture is treated with basic lead acetate, 
a precipitate is formed which contains nearly all of the 
carnine in a state of combination with the lead. The 
precipitate is separated by filtration, boiled with water, 
which then dissolves the compound of lead and carnine, 
and the mixture is filtered boiling. A current of hydrogen 
sulphide is passed through the filtrate, and the lead sul- 
phide is removed by filtration. The filtrate is concen- 
trated to a small bulk, and allowed to stand until part 
of the carnine is deposited in dark-colored crystalline 
masses. After separating this deposit, the mother- 
liquor is treated with a solution of silver nitrate, which 
precipitates silver chloride, and a silver compound of 
carnine ; the latter is only slightly soluble in ammonia ; 
the precipitate is therefore treated with ammonia, which 
dissolves the silver chloride, and the compound of silver OXALURIC ACID-. 
45 
and carnine is washed with water, suspended in boiling 
water, and decomposed by hydrogen sulphide. The fil- 
tered liquid is then concentrated, decolorized with animal 
charcoal, and allowed to crystallize. Notwithstanding 
inevitable losses, this process yields about one per cent, 
of carnine. 
Carnine forms small, white, poorly-crystallized masses, 
which are only slightly soluble in cold water, but dissolve 
readily in boiling water. It is insoluble in either alcohol 
or ether. Its aqueous solution, which is neutral, is not 
precipitated by neutral lead acetate, hut yields an abun- 
dant precipitate with basic lead acetate, if no neutral 
acetate he present. 
It combines with hydrochloric acid, forming a hydro- 
chloride which crystallizes in brilliant needles and forms 
a double salt with platinic chloride. 
When heated wdth chlorine water and a trace of nitric 
acid, it leaves a white residue which assumes a red color 
when exposed to ammonia vapors.' This reaction seems 
to indicate the formation of hypoxanthine, which acts in 
the same manner. 
Oxaluric Acid. 
C3H4N204. 
§ 56. The ammonium salt of this acid is, according to 
Schunck and Neubauer, normally contained in human 
urine. The acid itself is a derivative of uric acid, and 
ammonium oxalurate is formed when parabanic acid* is 
heated with ammonia. 
Large quantities of urine (about 50 litres) are re- 
quired for the detection of ammonium oxalurate. The 
fresh urine, having an alkaline reaction, and previously 
filtered, is filtered through animal charcoal, which ab- 
sorbs the oxalurate, with much of the other salts. The 
charcoal is then thoroughly washed with water to remove 
chlorides and sulphates, and dried at a gentle heat; it 
is then exhausted with boiling alcohol, the alcoholic 
liquid is filtered and evaporated to dryness, and the 
residue extracted with warm water; the brown aqueous 
* Oxalyl-ureide, C3H2N203. It is formed by the action of an ex- 
cess of nitric acid on alloxane or on uric acid. 46 
ORGANIC PROXIMATE PRINCIPLES. 
solution is concentrated to a syrupy consistence, and, 
after long standing in a cold place, will deposit crystals 
of ammonium oxalurate. The crystals are washed with 
absolute alcohol, redissolved in water, and the solution 
is decolorized by animal charcoal and recrystallized. 
Ammonium oxalurate crystallizes in silky white 
needles, which may be heated to 120° without decom- 
position. If a tolerably dilute solution of this salt be 
mixed Avith calcium chloride and ammonia, no precipitate 
is formed; but, when the mixture is heated, calcium 
oxalate is thrown down, and may be recognized by its 
crystalline form and its chemical properties. 
C4H9F02fH20. 
Creatine. 
§ 57. If several pounds of flesh be finely divided, 
digested for some time in cold water, and then tho- 
roughly pressed, a red liquid is obtained which contains 
a little blood, together with the constituents of the mus- 
cular juices. These are principally albumen, creatine, 
possibly inosite, paralactic acid, butyric acid, and mineral 
salts, chiefly phosphates and chlorides. 
Normal urine contains little or no creatine, that which 
is sometimes found in it being produced from creatinine 
(Heintz). 
A tolerably large quantity of meat (15 or 20 pounds 
of beef) must be used for the extraction of creatine, 
which may be prepared as follows : the flesh is cut into 
minute fragments, triturated with powdered glass, and 
then mixed with one and a half times its weight of alco- 
hol and gently heated on a water-bath. The liquid 
which is extracted bv strong pressure is distilled to re- 
cover the alcohol, and, after diluting with water and fil- 
tration, if necessary, basic lead acetate is added, care 
being taken not to employ a large excess. The mixture 
is then filtered, and hydrogen sulphide is passed through 
the clear filtrate to precipitate the excess of lead, which 
is separated by another filtration. The solution is then 
cautiously evaporated to a somewhat syrupy consistence 
on a water-bath and set aside for crystallization. The CREATINE. 
47 
crystals which separate are purified by washing with 
strong alcohol, dissolving them in water, and reorystal- 
lization, after treatment with animal charcoal. 
Pure creatine forms brilliant, transparent, and color- 
less oblique-rhombic prisms (Fig. 15), containing one 
Fig. 15. 
Creatine. 
molecule of water, which they lose at 100°, becoming 
at the same time opaque. It dissolves readily in boiling 
water, and separates from its saturated solution, on cool- 
ing, in fine needles. From more dilute solutions it is 
slowly deposited in large crystals. It is almost insoluble 
in strong alcohol, and insoluble in ether. The aqueous 
solution is neutral, has a somewhat bitter taste, and soon 
decomposes. With acids, creatine forms crystallizable 
salts which are soluble in water and readily decomposed. 
When treated with strong acids, or by long boiling 
with water, creatine is decomposed into creatinine and 
water. 
C4H9N302 = C4II7N30 4- 1I20. 
If long boiled with baryta-water it is converted into 
sarcosine and urea, and, if the action of the reagent be 
further prolonged, the urea is decomposed into carbon 
dioxide and ammonia. 
C4H9N302 4- H20 = C3PI7N02 + C0N2H4. 48 
ORGANIC PROXIMATE PRINCIPLES. 
When a solution of creatine is boiled with an excess 
of mercuric oxide, carbon dioxide is disengaged, and 
metallic mercury is deposited. 
Sarcoxine, C3H7N02, does not appear to exist in the 
body. 
Creatinine. 
C4H7N30. 
§ 58. Creatinine exists normally in human urine, and 
in that of the dog, horse, and calf. Although it may be 
extracted from the muscular juices and the blood, it is 
probably then formed, in operating, from the creatine 
contained in those liquids. As has already been seen, 
creatinine may be readily prepared from creatine by 
boiling with dilute acids, hydrochloric acid answering 
best. The resulting compound of creatinine and hydro- 
chloric acid is decomposed by an excess of lead hydrate, 
and the filtered solution is allowed to crystallize. 
Creatinine forms colorless, oblique-rhombic prisms 
(Fig. 16), quite soluble in cold water, more so in boding 
Fig. 16. 
water, and also soluble in boiling alcohol, from which, 
however, the greater part again separates on cooling. 
Creatinine. CREATININE. 
49 
Its solutions have an alkaline reaction, and creatinine 
forms well-defined salts with the acids. 
If silver nitrate be added to an aqueous solution of 
creatinine, a voluminous, white, crystalline precipitate is 
formed, consisting of a basic combination of the two com- 
pounds. 
Mercuric chloride also occasions a white precipitate 
which soon becomes crystalline. 
The most important reaction of creatinine, and one 
which distinguishes it from creatine, is its behavior with 
zinc chloride. If a syrupy solution of the latter com- 
pound be added to an aqueous solution of creatinine, a 
white, grainy, crystalline precipitate—a compound of 
creatinine and zinc chloride—is immediately formed, and 
the appearance of this precipitate under the microscope 
is quite characteristic (Fig. 17). It is scarcely soluble 
Fig. 17. 
Zinc chloride and creatinine. 
in cold water, quite insoluble in alcohol. Zinc chloride 
does not precipitate creatine. 
§ 59. Detection.—It is sometimes desired to test for 
creatinine in the urine ; for this purpose the latter is 
neutralized with a little milk of lime, and sufficient cal- 
cium chloride is added to precipitate all the phosphoric 
acid as calcium phosphate. The liquid is then filtered 
and concentrated on the water-bath. The residue is ex- 50 
ORGANIC PROXIMATE PRINCIPLES. 
hausted with absolute alcohol, and the filtered liquid is 
allowed to stand several hours, when it is again filtered 
and mixed with a neutral syrupy solution of zinc chloride. 
After a time, the double compound of zinc chloride and 
creatinine separates as a yellow precipitate. This is 
collected, washed with cold water, then dissolved in boil- 
ing water, and the zinc and hydrochloric acid are re- 
moved by digestion with lead hydrate. The filtered 
solution is decolorized by animal charcoal, evaporated to 
dryness, and the residue, which is a mixture of creatine 
and creatinine, is treated with boiling alcohol. As this 
solution cools, the creatine crystallizes out, while the 
creatinine remains in solution, and may he obtained in 
crystals by evaporation of the alcohol (Neubauer). 
When the creatinine is thus obtained pure, it may be 
distinguished from creatine by its solubility in cold alco- 
hol, by the alkaline reaction of its concentrated aqueous 
solution, by its crystalline form, and by its behavior wTith 
zinc chloride. 
According to Neubauer, 200 or 300 c. c. of urine are 
sufficient for its detection. It is generally advisable, 
however, to use a larger quantity. 
Leucine. 
C6H13N02. 
§ 60. Leucine exists in the glandular organs, and has 
been found in the lungs, spleen, liver, kidneys, in the 
thyroid and salivary glands, and especially in the pan- 
creas. It is also met with in the urine of patients suf- 
fering from diseases of the liver. 
Leucine is a product of the decomposition of albuminoid 
matters, either by acids, alkalies, or putrefaction. It 
may be most easily prepared by boiling 2 parts of horn- 
shavings, for about twenty-four hours, with 5 parts of 
sulphuric acid and 13 parts of water, the latter being 
replaced as it evaporates. Milk of lime is then added 
to the mixture, and the precipitated calcium sulphate is 
separated by filtration. The lime remaining in the fil- 
trate is exactly precipitated by oxalic acid, and the 
liquid again filtered and evaporated to crystallization. LEUCINE. 
51 
Leucine and tyrosine are deposited together. They 
may he separated by rather weak alcohol, in which 
tyrosine is insoluble; or the mixture may he dissolved in 
boiling Avater to which a little ammonia has been added, 
and the hot solution treated Avith solution of basic lead 
acetate and agitated until the precipitate becomes white. 
The mixture is then filtered, and the filtrate boiled and 
exactly neutralized Avith sulphuric acid. Nearly all of 
the tyrosine is thus precipitated, and, after another fil- 
tration, the liquid is freed from lead by a current of 
hydrogen sulphide and again filtered and boiled. An 
excess of recently precipitated cupric hydrate is added, 
and the mixture boiled for some time. The leucine com- 
bines Avith part of the cupric hydrate; the combination, 
together Avith the excess of cupric hydrate, is separated 
by filtration, washed, suspended in Avater, and decom- 
posed by hydrogen sulphide. A little acetic acid is then 
added, and the clear liquid obtained by filtration is de- 
colorized by animal charcoal, evaporated to a small bulk, 
and alloAved to crystallize. Nearly pure leucine sepa- 
rates. 
§ 61. Leucine crystallizes in small, brilliant, Avhite 
Fig. 18. 
Leacioe. 
laminae (Fig. 18). It is soluble in 27 parts of cold 
water, and in a much less quantity of boiling water ; it 52 
ORGANIC PROXIMATE PRINCIPLES. 
dissolves also in about 1040 parts of cold or in 800 parts 
of boiling alcohol. It is much more soluble in weak 
alcohol, insoluble in ether. 
When heated to 170°, it melts and partially sublimes, 
but above that temperature it decomposes into carbon 
dioxide and amylamine. 
Solutions of leucine are not precipitated by metallic 
salts, such as those of iron, mercury, silver, or lead, but 
if a solution of leucine be mixed with neutral lead 
acetate, the mixture heated to boiling, and ammonia 
carefully added, a compound of leucine and lead oxide 
separates in shining plates. 
Leucine dissolves in sulphuric, nitric, and hydrochloric 
acids, forming soluble crystallizable compounds. 
If leucine be moistened with nitric acid and cautiously 
heated on a platinum foil, a colorless residue remains ; 
if this be heated with a drop or two of sodium hydrate 
solution, it assumes a yellow or brown color, and is 
finally transformed into an oily compound. 
Ty rosine. 
C9H11N03. 
§ 62. Tyrosine occurs, together with leucine, in the 
spleen and pancreas, and in the liver when that organ is 
diseased, as well as in the urine of persons affected with 
softening of the liver. 
Like leucine, it is a product of the decomposition of 
albuminoid matters, and may he prepared from the resi- 
due of the preparation of leucine from horn. In the ex- 
traction of these compounds from the glands, the liquid 
is freed from albumen by ebullition, basic lead acetate 
is added, and the filtered solution treated precisely as 
indicated under leucine, except that, after all lead has 
been removed, the solution is evaporated and the leucine 
and tyrosine are separated by alcohol. 
Tyrosine crystallizes in snowy-white tufts of super- 
posed needles (Fig. 19). It is tasteless and odorless; 
not very soluble in cold water, but easily soluble in hot 
water, from which it separates almost entirely on cool- 
ing. It is insoluble in alcohol and ether, but quite solu- NEURINE. 
53 
ble in ammonia, in the mineral acids, and in solutions of 
the alkaline hydrates and carbonates. 
When a boiling aqueous solution of tyrosine is treated 
with a solution of mercuric nitrate, as neutral as possible, 
a voluminous light-yellow precipitate is formed. If now 
a few drops of dilute fuming nitric acid be added, and 
Fig. 19. 
the mixture again boiled, the precipitate becomes dark 
red. If only a small quantity of tyrosine be present, a 
faint trouble will be at first perceptible, and, after boil- 
ing with fuming nitric acid, the mixture appears rose- 
colored and deposits dark-red flakes. 
§ 63. Tyrosine may be distinguished from leucine by 
its crystalline form and the contraction which the crys- 
tals undergo in drying ; by its difficult solubility in cold 
water and its insolubility in alcohol; by its decomposing 
when heated, while leucine may be sublimed; and by 
its reaction with mercuric nitrate. 
Tyrosine. 
Neurine or Choline. 
C5H15N02. 
§ 64. Neurine has been found in the bile of the pig 
and the ox, in the brain, and in the yolk of egg. In the 
latter two cases it does not exist in a free state, but in a 54 
ORGANIC PROXIMATE PRINCIPLES. 
complex body known as lecitliine, and it has thus far 
been found in the human body only in that form. 
It may be extracted from yolk of egg or from the bile, 
but in this case it may result from the decomposition of 
lecithine (see § 72). The following process is recom- 
mended by Diakonow : Yolk of egg is exhausted suc- 
cessively with ether and boiling alcohol, and the residue 
left after the distillation of the united extracts is boiled 
for an hour with baryta-water. The excess of baryta is 
precipitated by carbon dioxide, the liquid filtered, and 
evaporated to dryness. The residue is extracted 'with 
absolute alcohol, the solution filtered, and precipitated 
by platinic chloride. A yellow double chloride which is 
insoluble in alcohol is precipitated; it is collected, Avashed 
with alcohol, dissolved in water, and freed from platinum 
by hydrogen sulphide. The filtered liquid, containing 
neurine hydrochloride, is evaporated to crystallization in 
a vacuum, and the neurine is set free by digestion with 
silver oxide. 
The same process may be applied to the extraction of 
neurine from bile, which must first be freed from mucus 
and albuminoid matters. 
Neurine is a syrupy liquid having a strong alkaline 
reaction and marked basic properties. Its aqueous solu- 
tion is decomposed by boiling into glycol, trimetliylamine, 
and ethylene oxide. Solutions of neurine hydrochloride 
are precipitated pure yellow by auric chloride, the double 
salt formed being difficultly soluble in cold water, and 
crystallizing from boiling water in small yellow needles 
or rhombic laminae. With platinic chloride, neurine 
forms a double salt which is insoluble in alcohol, but 
crystallizes from water, by spontaneous evaporation, in 
large, orange-red, oblique-rhombic prisms. 
Neurine is trimethyl-hydroxethylene-ammonium hy- 
drate. 
Taurine. 
§ 65. In the human economy, taurine is found in the 
bile and in the intestinal canal, where it exists as a de- 
composition product of taurocholic acid. It is produced 
C2H7NS03. TAURINE. 
55 
by the decomposition of the latter acid by acids, alkalies, 
or by putrefaction. Its presence has also been demon- 
strated in the muscular juices and in the liquid of the 
lung tissues. 
Taurine is most easily extracted from ox-gall. This 
is boiled for several hours with dilute hydrochloric acid, 
filtered, and the filtrate evaporated to dryness. The 
residue is treated with absolute alcohol to remove 
glycocol hydrochloride, and then dissolved in water and 
allowed to crystallize. The product may be purified by 
solution in very dilute alcohol, and precipitation by neu- 
tral lead acetate ; the filtered liquid is freed from lead 
by hydrogen sulphide and another filtration; it may then 
be evaporated to dryness, washed with absolute alcohol, 
and recrystallized in water. 
Taurine forms large, brilliant, oblique-rhombic prisms 
(Fig. 20), soluble in 15 or 16 parts of cold and in much 
Fig. 20. 
Taurine. 
less boiling water, insoluble in absolute alcohol and in 
ether. The crystals melt when heated, and beginto de- 
compose at 240°. 
When heated on platinum foil they increase in volume 
and disengage sulphurous oxide, leaving a residue of 
difficultly combustible charcoal. If taurine be calcined 56 
ORGANIC PROXIMATE PRINCIPLES. 
with sodium carbonate, sodium sulphide is formed, and 
the mass disengages hydrogen sulphide when moistened 
with acids. 
Taurine is amid-isethionic acid. 
Glycocholic Acid. 
C26H43N06. 
§ 66. As a sodium salt, glycocholic acid is a constant 
and important constituent of the bile of herbivorous 
animals: it exists abundantly in ox-gall, but in much 
smaller proportion in human bile. Traces of it have been 
found in icteric urine. It may be prepared by decolor- 
izing ox-gall by animal charcoal, evaporating to dryness, 
and dissolving the dry residue in absolute alcohol. Ether 
is then carefully poured on the surface of the solution, 
so that the two liquids may not mix. As diffusion slowly 
takes place between the ether and alcohol, sodium gly- 
cocholate is deposited in crystals. These are dissolved 
in water, and on the addition of dilute sulphuric acid the 
glycocholic acid separates in fine needles, which are only 
slightly soluble in cold water, more soluble in boiling 
water and in alcohol, insoluble in ether. It does not 
crystallize from its alcoholic solution, but on evaporation 
is left as a resinous mass. 
Its solutions are dextrogyrate. 
In examinations for glycocholic acid, the pure acid 
must be obtained. It is distinguished from cholic acid 
by its crystalline form, and by the fact that the latter 
acid contains no nitrogen. Glycocholic acid always 
crystallizes in fine needles. 
§ 67. If an aqueous solution of glycocholic acid be 
mixed with two or three drops of solution of sugar, and 
concentrated sulphuric acid be gradually added, taking 
care that the mixture does not become heated, the liquid 
assumes first a cherry-red, then a purple-violet color. 
The sulphuric acid should be absolutely pure. This re- 
action is not peculiar to glycocholic acid, but is common 
to all the biliary acids (Pettenkofer). 
When glycocholic acid is long boiled with dilute hydro- 
chloric acid, or with baryta water, it is decomposed by TAUROCHOLIC ACID. 
57 
hydration into glycocol (C2H5N02), and cholic acid 
(C24H40O5). 
Taurocholic Acid. 
C26H45NS07. 
§ 68. This acid exists in ox’s bile, and is abundant in 
human bile; it is found alone in that of the dog, and has 
been detected in the bile of many animals, fishes, and 
serpents. It always occurs as an alkaline salt, and its 
sodium compound may be extracted from the ethereal 
solution from which sodium glyeocholate has deposited. 
The acid has not yet been obtained pure. It forms 
fine, silky needles, which rapidly deliquesce in the air. 
It is soluble in water and alcohol, insoluble in ether. Its 
solutions are dextrogyrate. When its aqueous solution 
is boiled with dilute acids, alkalies, or even alone, it 
breaks up into cholic acid and taurine. 
Taurocholic acid is best extracted from dog’s bile by 
the process adopted for the preparation of glycocholic 
acid. The crystals deposited by the ether are dissolved 
in a little water, and treated with basic lead acetate and 
ammonia. The precipitate is washed, suspended in 
alcohol, decomposed by hydrogen sulphide, and the 
filtered liquid is concentrated to a small bulk, and an- 
hydrous ether added. The precipitate which is formed, 
gradually becomes transformed into silky needles, which 
are deliquescent in the air. 
§ 69. Taurocholic acid is separated from glycocholic 
and cholic acids by the addition of neutral lead acetate 
to the neutral mixture. Lead cholate and glyeocholate 
are insoluble, while the taurocholate remains in solution. 
The filtered liquid is mixed with basic lead acetate and 
ammonia; the precipitate formed is suspended in alcohol, 
and may be decomposed by hydrogen sulphide, or it may 
be mixed with sodium carbonate, the mixture evaporated 
to dryness, and extracted with alcohol, which dissolves 
only sodium taurocholate. 
Taurocholic acid gives the reaction indicated in § 67, 
and if it be heated with sodium carbonate and nitrate, 
the residue will be found to contain sulphur. 58 
ORGANIC PROXIMATE PRINCIPLES. 
Cholic Acid. 
C24H40O5. 
§ TO. Traces of cholic, or as it is sometimes called, 
cliolalic acid, are found in the contents of the small intes- 
tine and in icteric urine ; it exists in larger quantity in 
the large intestine and in the excrements. 
It is a product of the decomposition of glycocholic and 
taurocholic acids, and may he easily prepared by boiling 
for twenty-four hours in saturated baryta water the pre- 
cipitate produced by ether in an alcoholic solution of 
bile. The barium cholate formed is then washed, de- 
composed by hydrochloric acid, and the cholic acid set 
free is purified by several crystallizations in alcohol. 
It crystallizes in transparent and colorless tetrahedra, 
which soon become opaque in the air. It is almost in- 
soluble in water, readily soluble in alcohol, less so in 
ether. It separates from boiling alcohol in quadratic 
crystals, containing 5 molecules of water of crystalliza- 
tion ; from ether in four-sided prisms, containing 2 mole- 
cules of water. 
§ 71. If a small quantity of cane-sugar and a few 
drops of concentrated sulphuric acid be added to an 
aqueous solution of cholic acid, taking care to add the 
acid drop by drop so that the liquid does not become 
heated, a precipitate is first formed, but is redissolved 
by an excess of acid. On heating the mixture to about 
70°, it assumes a cherry-red color, which changes to 
purple, and gradually becomes darker, until in a week’s 
time, it is violet or blue (Pettenkofer). This reaction 
is common to the other biliary acids, from which, how- 
ever, cholic acid is distinguished by its crystalline form, 
and by its solubility in ether. 
Lecithine. 
C^H^NPO9. 
§ 72. Lecitliine has been found in most of the cellu- 
lar liquids, both animal and vegetable, and notably in 
the blood, exudations, and bile. It exists in considerable 
quantity in the brain, nerves, and in the yolk of egg. CYSTINE. 
59 
The latter substance serves well for its preparation. 
Yolk of egg is exhausted with a mixture of alcohol and 
ether, and an alcoholic solution of cadmium chloride is 
added to the filtered liquid. A white, flocculent precipi- 
tate, a compound of cadmium chloride and lecithine 
hydrochloride, is thrown down; this is washed with 
alcohol and ether, then suspended in water and decom- 
posed by hydrogen sulphide. The filtered solution is 
evaporated, and deposits lecithine hydrochloride as a wax- 
like mass. When the alcoholic solution of this compound 
is decomposed by silver oxide, lecithine is set free, and 
after filtration and evaporation remains as a translucid 
homogeneous mass. 
Lecithine and all of its compounds are very alterable. 
It decomposes slowly in the cold, rapidly at a moderate 
temperature, and even when its alcoholic solution is 
boiled for some time. 
When an alcoholic solution of lecithine hydrochloride 
is boiled with baryta-water, barium oleate and palmitate 
are precipitated, and barium phosphoglycerate and neu- 
rine remain in solution (see § 64). 
§ 73. Piiosphoglyceric Acid, C3H9P06.—This has 
been said to exist in the brain, nerves, and bile, but it is 
probably formed by the decomposition of lecithine, during 
the chemical operations employed for its preparation. 
Cystine. 
C3H7NS02. 
§ 74. Cystine is found in rare renal and vesical cal- 
culi, and as a sediment in pathological urine. 
It may be prepared by dissolving cystic calculi or 
cystic urinary sediment in ammonia, and allowing the 
solution to evaporate. Cystine is then deposited in 
colorless hexagonal tables (Fig. 21) or rhombohedra; 
these crystals sometimes assume the forms of uric acid 
(6, 5, Fig. 22), from which, however, they may be 
readily distinguished by their solubility in ammonia. 
Cystine is insoluble in alcohol, water, and ether, but 
dissolves readily in alkaline solutions and in mineral 60 
ORGANIC PROXIMATE PRINCIPLES. 
acids ; it is precipitated from the former by acetic acid, 
and from the latter by ammonium carbonate. 
Fig. 21. 
Cystine. 
If cystine, or a portion of a cystic calculus, be dis- 
solved in a small quantity of an alkaline solution, and the 
liquid be diluted with water and potassium nitroferrocy- 
anide added, a rich violet color is produced (J. Muller). 
Fig. 22. 
Cystine. 
When cystine is boiled with potassium hydrate, ammo- 
nia is disengaged, and an alkaline sulphide is formed ; ALBUMINOID BODIES. 
61 
if, then, a substance containing cystine be boiled with a 
solution of lead oxide in potassium hydrate, a black pre- 
cipitate of lead sulphide is thrown down. 
Cystine is also readily recognized by its crystalline 
form as seen under the microscope. The suspected cal- 
culus or deposit is dissolved in ammonia ; a few drops of 
the solution are placed on a microscope slide and covered 
with a thin glass. As the ammonia volatilizes, charac- 
teristic hexagonal tables are formed. 
Albuminoid Bodies. 
§ 75. With the exception of the bile, tears, and urine, 
the greater part of the liquids and tissues of the body 
are composed of substances having nearly the same 
chemical composition, and presenting such similar pro- 
perties that it is sometimes difficult to distinguish be- 
tween certain of them. 
These substances, so important to the constitu'ion of 
organized matter, receive the general name albuminoid 
bodies. They possess properties analogous to those of 
white of egg. They are solid, amorphous—excepting 
hemoglobin, which is crystallized—odorless, and almost 
tasteless. They are insoluble in alcohol, ether, and all 
neutral organic liquids. They are sometimes soluble in 
water, sometimes insoluble ; their solubility may gene- 
rally he traced to the presence of alkalies, acids, or 
mineral salts. Their solutions rotate the plane of polar- 
ized light to the left. 
All of these bodies contain carbon, hydrogen, oxygen, 
nitrogen, and sulphur, and, disregarding traces of mineral 
salts from which it is difficult to completely separate 
them, they present nearly the same centesimal composi- 
tion, which is as follows :— 
Carbon ....... 54.3 
Hydrogen . . . . . . .7.1 
Oxygen . . . . . . .21.0 
Nitrogen ....... 15.8 
Sulphur 1.8 
In contact with water they gradually decompose, and 
are converted into other substances ; their tendency to 62 
ORGANIC PROXIMATE PRINCIPLES. 
putrefy distinguishes them from other organic bodies, 
and, when decomposing, they evolve hydrogen sulphide. 
When heated they swell up and decompose, disengag- 
ing ammonia, carbon dioxide, and pyrogenous products, 
and leaving a residue of nitrogenized carbon. If this be 
incinerated, a small residue of chlorides, phosphates, and 
sulphates of the alkaline or earthy metals is obtained. 
§ 76. They dissolve in solutions of the alkaline hy- 
drates, and are generally again precipitated from such 
solutions by the addition of acetic acid. The precipitate 
thus obtained seems to be identical, whatever may have 
been the albuminoid body employed. If lead acetate be 
added to the alkaline solution of an albuminoid body, a 
black precipitate is formed, indicating that the alkali has 
removed a portion of the sulphur from the albuminoid 
substance, forming a sulphide. 
a) When boiled with concentrated alkaline solutions, 
these compounds are decomposed, yielding principally 
formic acid, carbonic acid, glycocol, leucine, tyrosine, 
and an alkaline sulphide. 
b) Cold concentrated nitric acid communicates a yellow 
color to albuminoid substances, and the color is rendered 
more intense by warming; it is darkened to orange by 
the addition of ammonia. 
c) Concentrated hydrochloric acid dissolves them, es- 
pecially by the aid of heat, and the liquid assumes a blue 
or violet color if the reaction take place in contact with 
the air. 
d) Iodine colors them intensely yellow, and serves for 
their recognition under the microscope. 
e) They assume a red color when heated with Millon’s 
reagent (acid nitrate of mercury);* and this test is so 
delicate that it will indicate the presence of of 
albumen in aqueous solution. 
§ 77. a) Albuminous solutions are generally coagu- 
lated by boiling unless the liquid be alkaline, and, in 
* Millon’s reagent is prepared by dissolving, by the aid of heat, 
1 part of mercury in 2 parts of nitric acid of specific gravity 1.42 
and boiling at 120°. When the mercury is entirely dissolved, 2 
volumes of water are added to 1 volume of the solution, and the 
mixture is allowed to stand twenty-four hours. The clear liquid 
may then be decanted from the deposit which has formed. ALBUMINOID BODIES. 
this case, the coagulation may be brought about by the 
addition of a few drops of nitric acid. 
b) Albuminoid bodies are also precipitated from their 
aqueous solutions by mineral acids, acetic acid, and con- 
centrated solutions of alkaline salts, alcohol, solutions of 
tannin or of phenol, and by the salts of the heavy metals, 
such as lead basic acetate, mercuric chloride, cupric sul- 
phate. 
§ 78. For the detection of an albuminoid substance of 
undetermined nature in a liquid, one or two general re- 
actions are employed, and any positive results obtained 
may afterwards be confirmed if necessary. A portion of 
the liquid is boiled, and rendered acid by the addition of 
a little nitric acid ; if a precipitate be formed by boiling 
and be not dissolved by the nitric acid, or if the nitric 
acid occasion the formation of a precipitate, it may be 
assumed that an albuminoid substance is present. Nei- 
ther the formation of a precipitate by boiling alone, nor 
after the addition of nitric acid unaided by heat, can be 
regarded as conclusive evidence of the presence of albu- 
minoid matter. Thus, in urine, a precipitate formed by 
boiling, and redissolved by a few drops of nitric acid, is 
probably due to the presence of earthy phosphates, while 
a large proportion of uric acid may give rise to the for- 
mation of a precipitate on the addition of nitric acid 
unaided by heat; in the latter case, the precipitate is 
redissolved by boiling. In any case,-a large excess of 
nitric acid is to be avoided, since the albumen might be 
redissolved by that reagent. 
§ 79. An albuminoid substance may also be detected 
by acidifying the liquid with acetic acid, adding concen- 
trated sodium sulphate solution in volume equal to that 
of the suspected liquid, and heating to boiling; or the 
liquid, previously acidified with acetic acid, may be satu- 
rated with crystals of sodium sulphate and then boiled. 
The formation of a precipitate is indicative of the pres- 
ence of albumen. This method gives satisfactory results. 
§ 80. Albuminoid substances are generally entirely 
separated from their solutions by the addition of strong 
alcohol in sufficient quantity. If the solution be alka- 
line, it must first be acidified with acetic acid, and is ORGANIC PROXIMATE PRINCIPLES. 
then allowed to stand a few hours after the addition of 
the alcohol. 
By the action of oxidizing agents, such as potassium 
permanganate or chromic acid, albuminoid substances 
yield acids of the fatty series, acetic, propionic, butyric, 
valeric, and caproic, the corresponding aldehydes and 
nitriles, benzoic aldehyde, benzoic acid, etc. 
Gastric juice, natural or artificial, dissolves them, con- 
verting them into peptones, and it seems that in this 
reaction a peculiar modification of albumen, syntonin, is 
first formed. 
§ 81. Schiitzenberger classifies the albuminoid bodies 
as follows, and this classification is well adapted for the 
study of their more marked differences :— 
Albumen of white of egg and of serum.—Precipitated 
neither by acetic acid nor by orthophosphoric 
acid. 
Vitellin.—The albumen of yolk of egg. Appar- 
ently a mixture of albumen and casein. 
Globulin.— Found in the red corpuscles. Com- 
bined with hematin forms hemoglobin. 
Hemoglobin or hematocrgstall'in. Crystallizable. 
Hydropisin.*—Found n serous effusions (pleurisy, 
ascites). Differs from albumen only by being 
insoluble in a saturated solution of magnesium 
sulphate. Colored red by chlorine water. 
Pancreatin.*—Exists in the pancreatic juice. In- 
soluble in a saturated solution of magnesium 
sulphate ; colored red by chlorine water. Pos- 
sesses the property of rendering fats, starch, 
and albuminoid matters fit for assimilation. 
(Generally classed as a ferment.) 
Coagulated by heat. 
Alone. 
Soluble in water. 
In the presence of 
acetic acid. 
Paralbumen.*—A very viscous liquid found in 
ovarian cysts. Coagulates in flakes when its 
aqueous solution is boiled with acetic acid 
and potassium ferrocyanide. 
Metalbumen.*—Found in ascites. Is not preci- 
pitated by potassium ferrocyanide, and its 
solution is only slightly troubled by boiling 
with acetic acid. 
Casein of milk and legumin.—Alkaline albumin- 
ates ; coagulated by rennet; precipitated by 
both acetic and orthophosphoric acids. 
Soluble ferments. 
Peptones or albuminose.—Formed by the action 
of gastric juice on albuminoid matters. Not 
precipitated by acids. Precipitated by mer- 
curic chloride. 
Not 
coagulated 
by heat. 
* Distinctive characters not well marked. ALBUMEN. 
Insoluble in solution of potassium 
nitrate or in water containing 
ToVo °f hydrochloric acid. 
Soluble in solution of potassium ni- 
trate. 
Soluble in water containing 
hydrochloric acid. 
Soluble in alcohol 
Coagulated albumen. 
Cooked fibrin. 
Fibrin of blood. 
Myosin. 
Gluten and Syntonin. 
Glutine. 
Insoluble in water, 
Characters not well-marked ; dis- 
tinguished from other albuminoid 
bodies by not assuming a blue or 
violet color by the action of hydro- 
chloric acid and air. 
Ichtidin. 
Ichtulin. 
Emydin. 
§ 82. The albumen of serum of blood, sometimes called 
serin, is one of the most important constituents of the 
animal body ; it is* an essential and constant element of 
all the nutritive fluids. Thus it exists in the blood, 
chyle, lymph, in all of the serous fluids, in the muscles, 
and cellular tissue. Pathologically it is found in various 
effusions, in pus, urine, etc. 
In the liquids and organs of the economy, albumen 
always occurs in the liquid state, being probably held in 
solution in water by the presence of a small proportion 
of alkali. In this condition it very much resembles the 
albumen which constitutes the white of egg. Aqueous 
solutions of both substances deviate the plane of polarized 
light towards the left, but the rotatory power of egg 
albumen is inferior to that of serin. 
a) When a solution of albumen is heated, it becomes 
slightly turbid at 70°, and when the temperature reaches 
78°, the albumen coagulates either in a solid mass or in 
flakes, according to the concentration of the solution. 
Should the solution be alkaline, a part or the whole of 
the albumen may remain dissolved ; but if the alkali be 
previously neutralized by the requisite quantity of acetic 
acid, the whole of the albumen will separate in large 
flakes on boiling. Care must be taken not to add too 
much acid, otherwise the coagulation may be entirely 
prevented. 
Albumen thus coagulated is insoluble in water, alcohol, 
ether, and in cold dilute acids. By long boiling it is 
dissolved by acetic acid, and readily by hydrochloric 
Albumen. ORGANIC PROXIMATE PRINCIPLES. 
acid, the solution in the latter case assuming a dark, 
purple color. 
Nitric acid always produces a Avhite precipitate in 
solutions of albumen, but this precipitate is soluble in a 
large quantity of nitric acid, and in an excess of water. 
ft) An alcoholic solution of phenol precipitates albu- 
men, even when only minute traces are present. A 
solution of phenol which gives good results is composed 
as follows :— 
Crystallized phenol ... 1 part by weight. 
Cry stallizable acetic acid . . 1 “ “ “ 
Alcohol (90 per cent.) . . 3 “ “ “ 
10 cubic centimetres of this solution dissolve without 
producing a cloud in 100 c. c. of water or other liquid 
containing no albumen. (Mdhu.) 
c) Metaphosphoric acid completely precipitates albu- 
men from its solutions, and is one of the most delicate 
tests that can be employed. Ordinary phosphoric acid 
is without effect. 
EGG-ALBUMEN. 
§ 88. The albumen of white of egg closely resembles 
that from the serum of blood, but is not precipitated from 
its solutions by agitation with ether, as is the case with 
serum albumen. As has been seen, serum-albumen is 
soluble in concentrated hydrochloric acid ; when water 
is added to this solution a precipitate is at first formed 
but is easily dissolved by an excess of water. Egg- 
albumen is more difficultly soluble in hydrochloric acid ; 
the solution is precipitated by the addition of water, but 
the precipitate is not readily redissolved by an excess of 
that liquid. 
Egg-albumen injected into the veins or under the skin 
of animals, passes unchanged into the urine : this is not 
the case with serin. 
ESTIMATION OF ALBUMEN. 
§ 84. The proportion of albumen present in any liquid 
can only be estimated by coagulation, drying, and weigh- albumen. 
67 
ing. The coagulation may be effected by boiling, but 
may often be more conveniently brought about by the 
alcoholic solution of phenol before mentioned. Should 
only a small quantity of albumen be present, 100 cubic 
centimetres of the liquid to be examined, are filtered, 
acidified with 1 or 2 c. c. of nitric acid, and introduced 
into a stoppered bottle together with 10 c. c. of the 
phenol solution. The bottle is then closed, and well 
shaken in order to break up the coagulated albumen so 
that it may be readily washed. The liquid is then fil- 
tered through a tared filter, the precipitate thoroughly 
washed with boiling ivater charged with phenol, dried at 
100° and weighed. Should the liquid contain a large 
proportion of albumen, a smaller quantity (10-50 c.c.) 
is taken and diluted to 100 c.c. with distilled water, the 
treatment then being the same as before. (M<5hu.) 
§ 85. There are many bodies closely allied to albumen. 
Vitelltn is extracted from yolk of egg, by Avashing 
the latter with ether; it appears to be only a mixture of 
albumen and casein. 
Globulin is the coagulable principle of the red blood- 
corpuscles ; it much resembles albumen, but is distin- 
guished from it by being precipitated by carbon dioxide, 
while albumen is not. It is believed to be a product of 
the decomposition of hemoglobin. It, or an analogous 
body exists in the crystalline lens. Schmidt and Hoppe- 
Seyler consider it identical with the fibrino-plastic sub- 
stance (see farther on). 
Hydropisin has been found in the effusion of ascites ; 
it differs from albumen only by its insolubility in solution 
of magnesium sulphate. 
Pancreatin exists in the pancreatic juice ; it is colored 
red by chlorine, and has the property of converting 
starch, fats, and albuminoid bodies into digestible sub- 
stances. 
Paralbumen has been found in ovarian cysts : it is 
precipitated when heated with acetic acid and solution of 
potassium ferrocyanide. 68 
ORGANIC PROXIMATE PRINCIPLES. 
Metalbumen, which has also been encountered in 
dropsical effusions, is not precipitated wThen heated with 
potassium ferrocyanide, and only produces a faint cloud 
with acetic acid. 
Hemoglobin. 
§ 86. Hemoglobin,-which has also been called hemato- 
crystalline, is the coloring matter of the blood, and seems 
to be a combination of hematin and globulin. 
It may be prepared by triturating clotted blood with its 
own volume of water, and filtering through a cloth. The 
liquid is then frozen, or agitated with ether until the 
corpuscles are entirely dissolved. A coagulum is so 
formed, which removes all of the unbroken corpuscles from 
the liquid : the latter is then filtered, slightly acidulated 
with acetic acid, and alcohol is added as long as the pre- 
cipitate formed continues to redissolve. The red liquid 
is cooled to 0°, and after a time deposits crystals, which 
are collected on a filter, pressed, and washed with dilute 
alcohol and water, both at 0°. They may be purified 
by recrystallization by dissolving them in water, and 
evaporating the solution in a vacuum, or by adding alco- 
hol to it and cooling the mixture to 0°. 
These crystals differ in form and in solubility, accord- 
ing to the animal from whose blood they are obtained. 
Human blood, and that of the horse, fish, hedge-hog and 
dog, yield prismatic crystals, w'hile those obtained from 
the guinea-pig and mouse are tetrahedra, and are more 
difficultly soluble. 
Aqueous solutions of hemoglobin coagulate at 64°, and 
the crystals alter rapidly on contact with air. Alkalies 
and acids decompose them into hematin and globulin. 
Crystals of hemoglobin which have been dried in a 
vacuum at a low temperature, rapidly absorb oxygen and 
are converted into oxyhemoglolin. This compound exists 
in the red corpuscles of arterial blood ; it partially loses 
its oxygen in a vacuum, and entirely when submitted to 
the action of reducing agents, such as ammonium sulphide. 
Venous blood contains both oxidized hemoglobin and HEMOGLOBIN. 
69 
reduced hemoglobin. When the latter is agitated with 
air, it again absorbs oxygen. 
§ 87. When a solution of oxyhemoglobin is placed be- 
tween the source of light and the prism of a spectroscope, 
the spectrum is found on examination to contain two dark 
bands between Fraunhofer’s lines D and E. The darkest 
and most distinct is nearer D, the other is wider and less 
clearly marked (see Fig. 23). These bands are charac- 
teristic of oxyhemoglobin, and it is not necessary that 
the latter shall be isolated, natural blood answering per- 
fectly for the study of the bands. 
Fig. 23. 
Oxygenized Hemoglobin. 
Reduced Hemoglobin. 
Hemoglobin containing Carbon Monoxide. 
Hematin in Acid Solution. 
Hematin in Alkaline Solution. 
If a few drops of ammonium sulphide be added to the 
blood, and the mixture be heated to 80° or 40°, and its 
absorption spectrum again examined, the dark bands will 
be found to have disappeared, and in their place is seen 
a single band wider than either of the first, and in a 70 
ORGANIC PROXIMATE PRINCIPLES. 
position which would have been betAveen them. This 
absorption spectrum is characteristic of reduced hemo- 
globin. These properties permit the detection of very 
small quantities of blood, and are of great sendee in 
legal chemistry. 
Hemoglobin also combines Avith hydrocyanic acid and 
with carbon monoxide, the absorption spectrum being in 
each case characteristic. 
HEMATIN. 
§ 88. Hematin is a product of the decomposition of 
hemoglobin. It may be prepared by agitating defibri- 
nated blood with ether, adding acetic acid, again shaking 
for some time, and filtering the ethereal solution which 
separates. After standing for some time, the latter de- 
posits hematin, which is collected and washed with alcohol 
and ether. 
It is reddish-brown, amorphous, insoluble in water, 
alcohol, ether, and chloroform, but dissolves in acids 
and alkalies. Its solution, acidulated with acetic acid, 
gives a wide absorption band in the spectrum, replacing 
the line C. Its alkaline solutions give two absorption 
bands which merge together between D and E. These 
bands are also produced by acid or alkaline blood (see 
Fig. 23). After calcination, hematin leaves 12.8 per 
cent, of ferric oxide. 
HEMATIN HYDROCHLORIDE (HEMIN). 
§ 89. When a little hematin or a drop of blood is placed 
on a microscope slide, and treated with acetic acid and 
sodium chloride, small, flattened, rhomboidal crystals, 
having acute angles, are formed (Figs. 24 and 25). 
These crystals are hemin, and have been regarded as 
crystallized hematin, and as hematin hydrochloride. 
They have a reddish-broAvn color, and are insoluble in 
water, alcohol, and ether, hut soluble in concentrated 
alkaline solutions ; the solution is precipitated by acids, 
and by alkaline and earthy salts. This reaction is of 
great value in medico-legal researches for the recogni- 
tion of blood-stains. FIBRIN. 
71 
§ 90. Hematoidin, which has been found in old blood 
effusions, is a decomposition product of hemoglobin. It 
Fig. 24. 
Fig. 25. 
crystallizes in small, orange-red, transparent prisms. It 
is insoluble in water and alcohol, slightly soluble in 
ether, soluble in chloroform. It contains no iron (see 
bilirubin). 
Fibrin. 
§ 91. Blood which is drawn from the body coagulates 
spontaneously to a gelatinous mass, which gradually 
contracts as the serum is expressed, and becomes a net- 
work of elastic filaments. This coagulation is due to 
the production of fibrin ; and by beating the blood with 
a bundle of wires or twigs, the fibrin may be removed, 
as it is formed, in white, elastic filaments, which adhere 
to the rods. 
On drying, fibrin becomes hard and brittle, but again 
becomes elastic when immersed in water. It is insolu- 
ble in water, but dissolves in alkaline solutions, forming 
alkaline albuminates. Hydrochloric acid containing 
Y^j acid, dissolves it, forming syntonin. It dissolves 
at about 40° in solutions of potassium nitrate, sodium 
sulphate, and in ten per cent, solutions of common salt. 
These solutions coagulate when heated. 
§ 92. Fibrin does not exist already formed in the 
blood; it is produced by the combination of two sub- 
stances which have been named jibrinoyen and the fibrino- 
plastic substance; these bodies do not react upon each 
other in the vessels, but by causes which are not under- 
stood, combine as soon as the blood is drawn, and so 
form fibrin. According to Schmidt, the two substances 
may be isolated from each other as follows: Horse’s ORGANIC PROXIMATE PRINCIPLES. 
blood is received in a saturated solution of sodium sul- 
phate, the globules are separated by decantation, and 
carbon dioxide is passed through the liquid. A floccu- 
lent precipitate is formed, and is collected on a filter. 
After these flakes, which constitute the fibrinoplastic 
substance or paraglobulin (globulin) are removed, blood 
is no longer coagulable. If the current of carbon dioxide 
be long continued, viscous masses separate, and adhere 
to the sides of the vessel: these constitute the fibrinogen. 
These two substances are insoluble in boiled water, or 
in water charged with carbon dioxide, but they dissolve 
in aerated water and in solutions of the alkaline hy- 
drates and carbonates. Their solutions are not coagula- 
ble, even by heat; but when the two solutions are mixed 
together, coagulation immediately takes place, and fibrin 
is formed. 
Certain pathological fluids, such as the liquid of hydro- 
cele, do not coagulate spontaneously, but they contain 
fibrinogen, for they immediately coagulate in a solid 
mass when fibrinoplastic substance is added. Fibrinogen 
may be readily obtained by passing carbon dioxide 
through the liquid of hydrocele. 
Myosin. 
§ 93. This albuminoid substance exists in the liquid 
naturally contained in the sheaths of the muscles. This 
muscular juice is a thick, milky liquid which solidifies 
spontaneously in gelatinous masses of myosin. It also 
coagulates spontaneously after death, thus producing 
cadaveric rigidity. 
It is insoluble in water, and in a saturated solution of 
sodium chloride. It may be prepared from the muscles, 
by finely dividing them, washing the mass with Avater 
until it is decolorized, and then triturating with common 
salt, and enough water to make a 10 per cent, solution 
of the salt. Myosin is soluble in such a solution, and, 
after cold digestion for a few hours, the mixture is fil- 
tered, and solid rock salt introduced into the liquid. 
As the salt dissolves, the myosin is precipitated, not being 
soluble in saturated solutions of sodium chloride. Very SYNTONIN 
73 
dilute hydrochloric acid dissolves myosin, converting it 
into syntonin. 
Syntonin 
§ 94. Syntonin, which has also been described under 
the names musculin and parapeptone, may be prepared 
from muscular tissue. It appears to he the first product 
of the action of gastric juice, or of very dilute hydro- 
chloric acid upon albuminoid bodies. It is doubtful 
whether it pre-exists in the muscles, for it is probably 
formed from myosin by the method employed for its 
extraction. 
The muscular tissues are hashed, thoroughly washed 
with water, and triturated with water containing one 
thousandth part its weight of hydrochloric acid. The 
meat swells, and dissolves to a considerable extent; the 
mixture is pressed through a cloth, the liquid filtered, 
and exactly neutralized with sodium carbonate. The 
syntonin separates in colorless, gelatinous flakes, which 
dry upon the filter in elastic films. It may be prepared 
from fibrin, or from albumen, by the same process. 
Syntonin is entirely insoluble in water, but dissolves 
in water containing one-tenth per cent, of hydrochloric 
acid, or one per cent, of sodium carbonate. These solu- 
tions are not coagulated by heat, but are precipitated by 
water, sodium or magnesium sulphate, sodium chloride, 
etc. By the action of dilute sulphuric acid, syntonin 
yields leucine and ammonium sulphate. 
ALBUMINOSE OR PEPTONES 
§ 95. Albuminoid bodies are dissolved by gastric juice, 
and the solutions contain substances which have been 
named peptones: the latter differ, according to the albu- 
minoid body from which they are derived, but their differ- 
ences are only slightly marked. They possess the common 
properties of dissolving in water, of being precipitable 
by mercuric chloride, and of passing through membranes 
by osmose. Before being absorbed in the economy, albu- 
minoid bodies are converted into peptones, passing first 
through the intermediate form, syntonin. 74 
ORGANIC PROXIMATE PRINCIPLES. 
§ 96. Casein exists in solution in milk, from Avhich it 
is separated in the solid state by various reagents, par- 
ticularly on the addition of whey or acids. The same 
coagulation is brought about by the spontaneous forma- 
tion of lactic acid by the fermentation of the lactose. 
Acetic acid, ordinary phosphoric, and tartaric acids may 
be added to milk in considerable quantities without pro- 
ducing coagulation. 
Casein appears to be an alkaline albuminate, for the 
precipitate formed on the addition of an acid to its solu- 
tions, is identical with albumen. If solution of potas- 
sium hydrate be added drop by drop to white of egg, 
beaten up with its volume of water and reduced by 
evaporation at 40° to its original volume, the mass sets 
in a jelly. If this be thoroughly washed with a large 
quantity of water to remove the excess of alkali, and 
be then dissolved in warm water, a solution is obtained 
which presents all the characters of solutions of casein. 
It is precipitated by acetic acid, and the precipitate 
appears to be identical with coagulated casein. 
Coagulated casein is white, amorphous, very soluble 
in alkalies, alkaline carbonates, potassium nitrate, and 
sodium phosphate. It exhibits the general properties of 
albuminoid substances. 
Casein. 
Animal Ferments. 
§ 97. The saliva, gastric juice, and pancreatic juice, 
contain peculiar and active ferments, which are analo- 
gous to the albuminoid bodies, hut have the property of 
producing chemical transformation. 
(a) Ptyalin is the active principle of the saliva. Its 
aqueous solution rapidly converts starch into glucose ; in 
this respect it resembles diastase, a ferment derived from 
the vegetable kingdom, and it is not improbable that the 
two substances are identical. 
Ptyalin may be prepared in a sufficiently pure state, 
by acidulating the saliva with ortho-phosphoric acid, and 
then adding enough lime-water to render the liquid alka- ANIMAL FERMENTS. 
line. Calcium phosphate is thrown down, and carries 
with it the ptyalin, together with albuminous substances ; 
the precipitate is collected on a filter and washed with 
a little water, which dissolves out the ptyalin. On the 
addition of alcohol to the filtered liquid, the ptyalin is 
precipitated in light white flakes, which are converted 
into a yellowish powder when dried in a vacuum. This 
may he further purified by dissolving it in water, and 
reprecipitating by alcohol; and if the operation be re- 
peated several times, all albuminoid matter is removed, 
and the resulting ptyalin is almost white, and burns 
without leaving a mineral residue. 
(6) Pepsin exists in the gastric juice, and is pre- 
pared from the mucous membrane of the stomach. It is 
soluble in water and in dilute acids, and its solution in 
dilute hydrochloric acid is capable of digesting albumi- 
noid bodies, converting them into peptones. 
The preparation of pepsin is analogous to that of pty- 
alin, but the precipitated pepsin is not readily removed 
by water from the calcium phosphate. Hence the pro- 
cess must be somewhat modified. Briicke recommends 
the following method: the mucous membrane of the 
stomach is carefully cleaned, detached from the muscular 
coat, and digested at 58° in water acidulated with one- 
twentieth of sulphuric acid, until the greater part of the 
mass is dissolved. The liquid is filtered, and the filtrate 
neutralized with lime-water: the precipitated calcium sul- 
phate carries with it the pepsin, and the precipitate is 
collected on a filter, and washed with a little Avater. It 
is then dissolved in dilute hydrochloric acid, and the 
solution is gradually mixed with a solution of cholesterin 
in four parts of alcohol and one part of ether. The 
liquids are agitated together, and the precipitated cho- 
lesterin carries down the pepsin. The precipitate is col- 
lected, and washed first with very dilute acetic acid, 
then Avith Avater until all hydrochloric acid is removed. 
The cholesterin is then separated by shaking up the 
aqueous liquid containing the precipitate Avith ether, and 
the aqueous solution of pepsin is alloAved to evaporate 
spontaneously. So obtained, pepsin is a grayish-white, 
amorphous poAvder, soluble in Avater and dilute acids. 76 
ORGANIC PROXIMATE PRINCIPLES. 
The method of Wittich is the best for the preparation 
of a solution of pepsin which is intended to keep for any 
length of time. The well-cleaned mucous membrane is 
macerated with alcohol, and then scraped, di’ied, and pul- 
verized. The powder is macerated with glycerin,'which 
dissolves the pepsin ; and the latter may at any time be 
precipitated by the addition of alcohol. 
(c) The pancreatic juice probably contains three fer- 
ments, one of which converts starch into glucose; another 
transforms albuminoid bodies into peptones; and the third 
decomposes fats into fatty acids and glycerin (Dani- 
lewski). 
All of these bodies are colorless solids when pure; they 
are amorphous, arid are precipitated from their solutions 
by alcohol and lead acetate. They are not precipitated 
either by tannin or by mercuric chloride, nor are they 
colored yellow by nitric acid, as are albuminoid bodies. 
Very small quantities of these ferments are sufficient to 
effect the peculiar fermentations for which they are 
adapted, of an almost indefinite quantity of the fermenta- 
ble body, provided the products of the fermentation be 
removed from the liquid as they are formed; for the 
presence of these products frequently impedes the action 
of the ferment. The activity of these ferments varies 
with the temperature ; that of the human body, about 
85°, being most suitable for their action; too high a 
temperature—in every case below 100°—destroys the 
power of the ferment forever. 
Substances resembling Albuminoid Bodies. 
§ 98. Certain substances are related to the albuminoid 
bodies by their general chemical reactions, but differ 
somewhat from those bodies in their centesimal compo- 
sition. They are colored violet by strong hydrochloric 
acid. They contain approximately— 
Carbon ....... 50.0 
Hydrogen . . . . . . .6.6 
Nitrogen ....... 16.8 
Oxygen ...... 26.6 ALBUMINOID BODIES. 
77 
The bodies forming this group do not greatly differ 
from each other. 
OSSEIN. 
The bones contain a cartilaginous matter which may 
be extracted by dissolving out the earthy salts by hy- 
drochloric acid diluted with about nine parts of water. 
When the mineral matter is entirely removed, the ossein 
remains as a soft, elastic substance, preserving the form 
of the bone. It may be obtained from all tissues which 
furnish gelatin when boiled with water, such as the skin, 
cellular tissue, serous membranes, etc. Ossein soon de- 
composes when left to itself, but by the action of tannin 
and certain metallic salts, it is rendered unchangeable. 
GELATIN. 
All matters which contain ossein yield by long boiling 
with water a solution which sets in a jelly on cooling. 
When dry, gelatin is a colorless or yellowish, transpa- 
rent and vitreous solid; .it is brittle and sonorous, unal- 
tered by the air. In cold water it swells, and dissolves 
to a slight extent; boiling water dissolves it readily, and 
the solution gelatinizes on cooling. It is insoluble in 
alcohol. It is not precipitated by acids, by alum, or by 
the salts of lead, copper, silver, etc., but is thrown down 
by solutions of mercuric chloride. 
Tannin precipitates gelatin from its solutions. When 
boiled with dilute sulphuric acid, or with alkalies, gela- 
tin yields, among other products, leucine and glycocol. 
CHONDRIN. 
Chondrin is prepared by boiling the cartilages of the 
short ribs with water ; the solution gelatinizes on cool- 
ing, but the substance differs from gelatin in that its 
solutions are precipitated by all the acids, and by many 
metallic salts. Alum forms in it an abundant precipitate. 
When boiled with sulphuric acid, chondrin yields leu- 
cine, but no glycocol. 
Keratin is the name given to the basis of horny tis- 78 
ORGANIC PROXIMATE PRINCIPLES. 
sues, such as the nails and hair, or the horns and wool 
of animals. It is softened somewhat by boiling with 
water, but does not yield gelatin. It contains sulphur. 
Mucin is the substance which gives secretions of the 
mucous membranes their peculiar viscous, glutinous, and 
stringy properties. 
It may be extracted from ox-gall by agitating that 
liquid with three or four times its volume of alcohol, 
and collecting on a filter the impure mucin which is 
precipitated. This is then redissolved in water, the 
solution filtered, and the mucin precipitated by the ad- 
dition of acetic acid, in which it is insoluble. It is 
finally washed with alcohol. Mucin precipitated by 
acetic acid is not soluble in pure water, but if a trace 
of an alkaline hydrate, or carbonate, or even of an acid 
carbonate, be present, it dissolves readily. When pre- 
cipitated by alcohol, however, it dissolves in pure water, 
forming a viscous solution. 
Mucin may be distinguished by its being precipitated 
by acetic acid, an excess of which does not redissolve 
the precipitate. 
Animal pigments. 
§ 99. Numerous coloring matters exist in the body, 
and, with few exceptions,they are very imperfectly known. 
Many of those which have been described have undoubt- 
edly been produced by the action of the reagents em- 
ployed, and cannot be supposed to pre-exist in the body. 
With regard to many others, it has justly been said that 
their names are their most characteristic features. 
§ 100. The brown or black pigment to which the cho- 
roid owes its color, and which is deposited in the Mal- 
pighian bodies in the skin of animals and man, especially 
in the negro, has been named melanine. It exists also 
in the hair, in feathers, and in the skin of reptiles, 
fish, etc. Under the microscope, it appears in small 
granular masses which are often angular. It has not 
been well studied. 
The pigment of the eye, skin, etc., is rapidly destroyed 
by alkaline solutions, and by chlorine. It may thus be 
distinguished from carbon, which is sometimes mechani- BILIRUBIN. 
79 
eally deposited and encysted in the lungs and air passages, 
and which has there been sometimes mistaken for an 
animal pigment. 
The coloring matter of the blood, hematin, has already 
been described (§ 88). 
The biliary pigments have been well studied, and may 
be characterized without difficulty. 
Bilirubin. 
C16Hl8N203. 
§ 101. Bilirubin is found in biliary calculi, in the bile 
of man and other animals (ox-gall does not contain it), 
and sometimes exists pathologically in the blood and 
urine. It appears to he identical with the hematoidin 
which is found in microscopic crystals in old extravasa- 
tions of blood (see § 90). 
Bilirubin may be prepared from biliary calculi: they 
are pulverized, and exhausted with ether to remove the 
cholesterin; the residue is boiled with water, and then 
treated with dilute hydrochloric acid. The bile pig- 
ments are thus set free from their earthy combinations, 
and the portion which remains undissolved by the acid is 
thoroughly washed with water, dried, and then boiled 
with successive portions of chloroform as long as the 
latter removes coloring matter. The chloroform solution 
is filtered, the chloroform distilled off, and the residue 
treated with absolute alcohol which removes the bili- 
fuscin, but leaves the bilirubin undissolved. The latter 
is washed with a mixture of ether and alcohol, redissolved 
in chloroform, and precipitated by the addition of dilute 
alcohol to its solution. 
Bilirubin is thus obtained in orange-colored flakes. By 
the evaporation of its chloroform solution, it crystallizes 
in small, red, oblique-rhombic prisms. It is almost in- 
soluble in water, alcohol, and ether, but dissolves easily 
in carbon disulphide, benzol, and chloroform, from which 
solvents it is precipitated by the addition of alcohol. 
It is also quite soluble in solutions of the alkaline 
hydrates and carbonates, forming orange-red solutions, 
which become green on exposure to the air. Ilydro- 80 
ORGANIC PROXIMATE PRINCIPLES. 
chloric acid precipitates it from its alkaline solutions. 
The alkaline compounds of bilirubin are insoluble in 
chloroform. 
If concentrated sulphuric acid be added to a chloro- 
formic solution of bilirubin, the liquid assumes a green 
color. 
§ 102. If an alkaline, aqueous solution of bilirubin be 
poured on the surface of nitric acid containing a little 
nitrous acid, in a test-tube, or on a mixture of strong 
nitric and sulphuric acids, green, blue, violet, red, and 
yellow shades are developed at the surface of contact of 
the liquids. If the liquids be agitated together, the 
colors are produced successively in the order mentioned, 
but if care be taken to prevent their mixture, all of the 
colors may be observed at the same time (Gmelin). This 
reaction is characteristic and sensitive, but no alcohol 
should be present. 
Ammoniacal solutions of bilirubin are precipitated by 
calcium chloride, barium chloride, lead nitrate, and sil- 
ver nitrate. 
Biliverdin. 
C16H18JN204. 
§ 103. This coloring matter has not yet been certainly 
found in the bile or in biliary calculi, as a pre-existing 
compound, for it is probably formed in its extraction by 
the oxidation of bilirubin. It may, however, exist in the 
green bile of the ox, as well as in human bile which has 
a green color, and in icteric urine. 
When a solution of bilirubin in sodium hydrate is 
agitated in contact with air, it assumes a green color, 
and hydrochloric acid pricipitates biliverdin from the 
liquid. 
It is a bright green powder, insoluble in water, ether, 
and chloroform, but soluble in alcohol, to which it gives 
a bluish-green color. 
It also dissolves in glacial acetic acid, from which it 
separates on evaporation in green, ill-defined, rhombic 
tables. 
With nitric acid containing a trace of nitrous acid, alka- BILIFUSCIN—BILIPRASIN. 
81 
line solutions of biliverdin give the same series of colors 
as bilirubin, beginning, however, with the blue. 
The green color of bile or of icteric urine cannot be 
considered a proof of the presence of biliverdin. 
Bilifuscin. 
C16H20N2O4. 
§ 101. Bilifuscin exists in very small quantity in 
biliary calculi. 
It is prepared from the residue left after distillation of 
the chloroform in the preparation of bilirubin (§ 101). 
Alcohol extracts the bilifuscin from this residue, leaving 
the bilirubin undissolved. The alcoholic solution is eva- 
porated to dryness, exhausted with ether, to remove fatty 
matters, and the residue washed with chloroform and 
dissolved in absolute alcohol. The alcoholic solution 
being evaporated to dryness, leaves the bilifuscin as a 
brilliant, almost black, porous mass, which when pow- 
dered has a dark-green color. It is only very slightly 
soluble in water, ether, and chloroform, but dissolves in 
alcohol, forming a dark-brown solution. Its very dilute 
alcoholic solution has the color of icteric urine. 
Bilifuscin is soluble in dilute alkaline solutions, to 
which it gives a red-brown color, but these solutions gra- 
dually decompose on contact with the air. Hydrochloric 
acid precipitates them brown. 
Biliprasin. 
C16H22jS206. 
§ 105. This pigment occurs in biliary calculi, in ox’s 
bile, and probably in icteric urine. 
It is a brittle, brilliant black substance, which becomes 
clark-green when powdered. It is insoluble in water, 
ether, and chloroform, but dissolves in alcohol, forming a 
green solution which becomes brown on the addition of 
an alkali. It may be prepared from the residue of gall- 
stones which have been extracted with ether, water, 
hydrochloric acid and chloroform. 
With nitric acid containing nitrous acid, alkaline solu- 82 
ORGANIC PROXIMATE PRINCIPLES. 
tions of biliprasin give the same reaction as those of 
biliverdin, but the blue zone appears only after some 
time. 
Biliprasin is distinguished from biliverdin by the fact 
that its alcoholic solutions are colored brown by alkalies; 
from bilifuscin by the green precipitate produced by 
acids in alkaline solutions of biliprasin. 
Hydro bilirubin or Urobilin. 
C32H40N4O7. 
§ 106. This body, which may be obtained by the 
action of nascent hydrogen upon an alkaline solution of 
bilirubin, has been detected in febrile urine. By pre- 
cipitating the solution of reduced bilirubin by hydro- 
chloric acid, hydrobilirubin is obtained in reddish-brown 
flakes. Iloppe-Seyler has shown that an identical com- 
pound may be prepared by the action of hydrochloric 
acid and tin upon the coloring matter of the blood, or 
upon hematin. 
§ 107. The presence of hydrobilirubin in urine may 
be detected directly, and without preparation, by means 
of the spectroscope ; its absorption spectrum presents an 
intense dark band between the green and blue, or more 
definitely between the Fraunhofer lines b and F ; this 
band gradually fades towards F, and is nearer b than F 
when an alkaline solution is employed. 
Ilydrobilirubin is an amorphous, brown-red powder, 
very slightly soluble in water, but soluble in alcohol, 
ether, and chloroform. It is also soluble in alkalies, 
and, if zinc chloride be added to its strongly ammoniacal 
solution, the liquid becomes rose-colored, and acquires a 
green fluorescence; at the same time the absorption 
band becomes more intense if the liquid'be spectroscopi- 
cally examined. 
§ 108. Iloppe-Seyler has shown that normal urine 
does not contain hydrobilirubin, but a compound which, 
when precipitated by tribasic lead acetate, and the pre- 
cipitate decomposed by alcohol and sulphuric acid, grad- 
ually yields hydrobilirubin by spontaneous oxidation. 
This is the process described by Jaffe for the prepara- INDICAN. 
83 
tion of hydrobilirubin ; but in highly febrile urines the 
hydrobilirubin may be precipitated immediately by add- 
ing zinc chloride and ammonia. The zinc compound 
which is deposited is collected, washed with cold and 
then with hot water, decomposed by sulphuric acid and 
alcohol, and the filtered liquid agitated with half its 
volume of chloroform and an excess of water. The 
residue of the distillation of the chloroform extract con- 
sists of hydrobilirubin. 
The urochrome of Thudichum and the urohematin of 
Harley, seem to have been hydrobilirubin, more or less 
altered by the reagents used in the preparation of the 
pigments to which those names were applied. 
Indican. 
C26H31N017. 
§ 109. This compound, which is identical with the 
uroxanthin of Heller, is found in small quantity in 
normal urine, and often abundantly in pathological urine, 
especially in cases suffering from cancer of the liver. 
Its existence in the urine was discovered by Schunk. 
Indican is a substance analogous to the glucosides, 
and under the influence of acids is decomposed into 
indigotin, C8H5NO, and indiglucin, C6H10(J6; at the 
same time, indirubin (see further on) and other pro- 
ducts are generally formed. 
§ 110. Indican may be extracted from fresh urine as 
follows: albumen, if present, is removed, and the liquid 
is precipitated with basic lead acetate, and filtered ; the 
filtrate is mixed with ammonia, and the precipitate which 
forms is collected, washed, suspended in alcohol, and de- 
composed by hydrogen sulphide. The lead sulphide 
formed is separated by filtration, and the alcoholic liquid 
evaporated, first on a water-bath, and finally over sul- 
phuric acid in a vacuum. 
The indican is thus obtained as a light-brown syrup, 
soluble in all proportions of water, alcohol, and ether. 
It may be recognized by its decomposition into indi- 
gotin by boiling with hydrochloric acid. 
Under the influence of ferments, especially during the ORGANIC PROXIMATE PRINCIPLES. 
putrefaction of albuminous urine, indican decomposes 
spontaneously, and a small quantity of white indigo is 
formed ; this oxidizes into indigo-blue on exposure to the 
air, and the fact explains the appearance of blue pellicles 
having a red. metallic reflection, occasionally seen on the 
surface of putrid urine. Such pellicles consist of crys- 
tallized indigotin. 
Urines containing large quantities of indican disclose 
the presence of the latter substance when boiled with 
hydrochloric or dilute nitric acid; a pulverulent precipi- 
tate of indigotin is immediately formed and slowly de- 
posits. An excess of nitric acid would destroy the blue 
color. 
Small traces of indican may be detected by mixing the 
urine, contained in a test-tube, with about its own volume 
of fuming hydrochloric acid ; the presence of indican is 
indicated by a violet or intense blue color; the addition 
of two or three drops of nitric acid augments the deli- 
cacy of the test, but diminishes its permanence, the 
violet color changing to red and yellow (Heller). 
Indigotin (indigo-blue, uroglaucin). 
'C8I15N0. 
§ 111. Incligotin has not been found in the economy 
or in the excretions, but its presence, is frequently ob- 
served in putrid urine, where it is formed by the decom- 
position of indican. It is an amorphous, dark-blue 
powder, or crystallized in microscopic, right-rhombic 
prisms, grouped in stars. When in a mass, it leaves a 
brilliant copper-red trace on paper. It volatilizes when 
heated, yielding a crystalline sublimate having a copper- 
red reflection. 
It is insoluble in water, very slightly soluble in alco- 
hol and ether. It dissolves in fuming sulphuric acid, 
forming an intense blue solution, which is immediately 
bleached by nitric acid. 
Alcoholic solution of indigotin is also immediately de- 
colorized by ammonium sulphydrate and other reducing 
agents. 
The substances described as uroglaucin, urine blue, INDIGO-RED,INDIRUBIN. 
85 
and urocyanin were probably indigotin more or less 
pure, and of which the solubility was slightly modified 
by the foreign substances with which it was contaminated. 
Indigo-red, indirubin. 
§ 112. This substance, which was named urrJiodine 
by Heller, is amorphous, and has not been prepared in 
a state of purity. It may be obtained from the violet 
urine in which the indican has become decomposed, by 
filtering, adding acetic acid, and agitating the liquid 
with chloroform. On evaporation of the chloroform 
extract, the red substance remains ; it is very soluble in 
alcohol, ether, and chloroform. It is decolorized by 
ammonium sulphydrate, chlorine, and alkaline hypo- 
chlorites. PART IT. 
ANALYSIS OF SECRETIONS, EXCRETIONS, &c. 
URINE. 
§ 113. The urine is a complex liquid whose character 
and composition depend greatly upon the diet, manner 
of life, and other peculiarities of the individual. Its com- 
position varies also with the health, and a chemical 
analysis of the urine is often of great service as an aid 
to diagnosis ; hut it must be remembered that the relative 
quantities of the normal constituents of urine, vary within 
certain limits even in health, so that the conclusion must 
not be too hastily adopted that any one is in excess or 
in too small a proportion. 
Physical Properties 
§ 114. Normal human urine is a limpid, amber-colored 
liquid, having a peculiar, aromatic odor, a bitter, salty 
taste, and a decided acid reaction. Its specific gravity 
varies from 1005 to 1030, depending upon the propor- 
tions of solid and liquid food ingested, the time at which 
the urine is passed, and the amount of physical exercise 
taken by the individual. Urine which is voided soon 
after copious draughts of water or other , liquid is gene- 
rally pale in color, and has a low specific gravity; that 
passed after a meal has a high specific gravity, and is 
dark in color. The urine voided after a night’s rest has 
a mean specific gravity, and may be regarded as repre- 
senting the average composition of the total secretion for 
the twenty-four hours. The average specific gravity is 
about 1018, and the average daily amount of urine passed 
is about 1200 cubic centimetres, although a difference of 88 
URINE. 
several hundred cubic centimetres more or less may be 
perfectly normal and without clinical importance. 
§ 115. When allowed to stand, urine gradually de- 
posits a light, flaky cloud of mucus, and on cooling it 
often deposits a sediment of which the color is variable. 
When allowed to stand for some time, it becomes turbid 
owing to the separation of crystals of uric acid and 
acid urates (of sodium and ammonium), and finally 
acquires an ammoniacal odor, and an alkaline reaction. 
A whitish pellicle then forms on its surface, and the 
bottom of the vessel containing it is covered with a white, 
flocculent deposit, in which crystals of ammonio-mag- 
nesium phosphate are often discernible by the naked eye. 
The alteration is caused by the transformation of the 
urea present into ammonium carbonate, and the reaction 
of the sodium acid phosphate, to which normal urine 
owes its acidity, on the urates. Acid urates and uric 
acid are formed, and, being but slightly soluble, are de- 
posited, while the sodium acid phosphate is converted 
into neutral and basic salts. 
. § 116. The following substances are regarded as nor- 
mal and constant constituents of human urine:— 
Water, urea, uric and hippuric acids, creatinine, xan- 
thine, indican, vesical mucus, sodium chloride, potassium 
chloride, alkaline sulphates, sodium acid phosphate, cal- 
cium phosphate, magnesium phosphate, traces of ammo- 
niacal salts, iron, silica, and of nitrates and nitrites. 
§ 117. Small quantities of calcium oxalate, succinic 
acid, and glucose are also found from time to time in 
healthy urine, but these substances cannot be considered 
as constantly present. 
The substances formerly known as extractive matters 
are viscous bodies of which the chemical nature is un- 
known. 
§ 118. Normal urine is not coagulated by boiling, nor 
is it precipitated by acids: if it be mixed with nitric or 
hydrochloric acid, its color is darkened, and in the 
course of twenty-four hours a precipitate of uric acid is 
deposited. 
Normal Constituents of Urine ABNORMAL CONSTITUENTS. 
89 
Abnormal Constituents of Urine 
§ 119. The abnormal constituents of urine may be 
classified as abnormal substances proper, such as depend 
upon a pathological condition of the system, and acci- 
dental constituents which are derived from certain ali- 
ments, or which pass through the system unchanged and 
are eliminated by the kidneys; such are the mineral 
poisons and many remedial agents. 
§ 120. The abnormal constituents proper, and of 
which the amount present may vary greatly, are albu- 
men, glucose, inosite, lactic acid and the lactates, fatty 
matters, and the volatile fatty acids, succinic and benzoic 
acids, salts of the biliary acids, biliary pigments, cystine, 
leucine, tyrosine, hemoglobin, fibrin, pus and spermatic 
secretion, ammonium carbonate, calcium oxalate, hydro- 
gen sulphide. 
§ 121. The urine may be turbid when voided, and 
may subsequently become clear by the deposition of 
the substances which were held in suspension ; these sub- 
stances then constitute the sediment. Sometimes the 
urine is perfectly limpid when passed, and deposits an 
abundant sediment after standing for a short time. The 
nature of the sediment is revealed by microscopic exami- 
nation ; it more frequently consists of uric acid, urates, 
calcium oxalate, calcium phosphate, ammonio-magne- 
sium phosphate, mucus, epithelial cells, or sometimes of 
cystine, tyrosine, xanthine, pus cells, blood-globules or 
clots, tube casts from the kidney, spermatozoids, or in- 
fusoria. 
§ 122. The accidental constituents of urine may be 
traced to the aliments or medicaments from which they 
are derived. The alkaline carbonates pass unchanged 
into the urine, and render it alkaline ; the neutral alka- 
line salts of vegetable acids are usually eliminated as 
carbonates ; the soluble bromides and iodides may be 
detected in the urine shortly after their ingestion. The 
vegetable alkaloids are but little changed, or not at all. 
The essential oils of valerian, garlic, assafoetida, etc., 
communicate their peculiar odors to the urine ; after the 
ingestion of turpentine, the urine possesses an odor re- 90 
U1U N E. 
sembling that of violets. The pigments of gamboge and 
rhubarb pass into the urine. Oil of bitter almonds and 
benzoic acid are converted into hippuric acid ; asparagin 
and malic acid are eliminated as succinic acid. 
These and analogous facts must be borne in mind in 
the clinical examination of urine. 
Chemical Examination of Urine. 
§ 128. In a chemical examination of urine for the de- 
termination of the presence or absence of any abnormal 
substance, or of the proportions of the normal constitu- 
ents present, the urine of the 'whole twenty-four hours 
should be examined. As this is often impracticable, the 
chemical examination may be confined to the urine passed 
in the morning, before any liquid or solid food is in- 
gested ; the composition of such urine fairly represents 
the mean of the twenty-four hours. 
§ 124. Quantity.—A healthy adult excretes from 
800 to 1500 cubic centimetres of urine per day, accord- 
ing to the age of the individual, his 
weight, alimentation, and the physical 
exercise which he undergoes. 
This quantity varies greatly in dis- 
ease ; in certain affections the renal 
secretion is almost suppressed, while 
in the disease known as diabetes insi- 
pidus the quantity may be enormous ; 
exceeding ten, fifteen, or twenty litres. 
It has been found that there is a 
relation between the amount of urine 
excreted and the weight of the indivi- 
dual, so that per kilogramme of weight 
a healthy adult man passes about 1 
c. c. of urine per hour. Hence, a 
man weighing 60 kilos, should elimi- 
nate about 1440 c. c. per day. This 
approximation is in most cases very 
closely in accord with the facts. 
§ 125. Consistence.—Normal urine is mobile like 
water, and not at all viscous. When shaken in a bottle 
Fig. 26. GENERAL PROPERTIES. 
91 
which is half full, it froths in large bubbles which soon 
disappear. If the urine contain blood, pus, or biliary pro- 
ducts, the froth is much more abundant and persistent. 
§ 126. Specific Gravity.—The density of urine 
depends upon the proportion of water and solid constitu- 
ents, and so in great measure upon the amount of the 
secretion, since the actual quantity of solid matter daily 
excreted by the kidneys does not greatly vary. The 
specific gravity is determined by means of an urinometer 
(Fig. 26); care must be taken that the jar in which the 
instrument floats be large enough that the widest part of 
the urinometer may not touch the sides, and the degrees 
of the instrument must be read from below, looking 
through the liquid. The urinometer should be gradu- 
ated from 1000 to 1050. 
The temperature of the urine should always be ob- 
served when its density is determined. A difference of 
8° in temperature corresponds very nearly to one degree 
of the urinometer ; thus a sample of urine whose density 
is 1024 at 15°, will have a density of 1022 at 21°. 
In diabetes insipidus the density of the urine may be 
as low as 1001, while in saccharine diabetes it may 
attain 1050 or even 1070. A sample of urine having a 
high specific gravity should always be tested for glucose. 
The density of normal urine is generally comprised 
between 1014 and 1080, when excessive quantities of 
liquid are not taken. The mean density is about 1018, 
this corresponding to an excretion of about 1250 c.c. per 
day. In waim weather, when a large proportion of water 
is eliminated by the skin, the density of the urine is 
generally increased, while it is often correspondingly 
lowered in winter. 
§127. Reaction.—Normal human urine is acid; it 
immediately reddens blue litmus-paper. It may become 
alkaline if the individual be subjected to an exclusively 
vegetable diet, or if salts of vegetable acids, alkaline 
carbonates, or alkaline mineral waters, be freely ad- 
ministered. Urine voided immediately after a full meal 
is sometimes neutral or even slightly alkaline. 
The acidity of the urine cannot be attributed to uric 
acid, or to the small quantity of hippuric acid present, 92 
URINE. 
for a cold saturated solution of uric acid is almost without 
action on blue litmus-paper, and the boiling saturated 
solution produces but a wine-tint. 
It is regarded as almost beyond doubt that the sodium 
neutral phosphate which exists in the blood reacts with 
the uric acid, as both are eliminated together by the 
kidneys, forming sodium urate and sodium acid phos- 
phate. It is unquestionable that the latter salt is the 
cause of the acidity of normal urine. Free uric acid is 
not believed to exist in normal urine; it is almost insolu- 
ble in cold water, and would invariably be deposited as 
the urine cools. 
§ 128. To neutralize the entire acidity of the whole 
amount of urine passed in twenty-four hours, from 1 to 
1.5 grammes of sodium hydrate are required. It may 
sometimes be interesting to determine whether this nor- 
mal acidity is increased or diminished; the estimation is 
made by neutralizing 100 c.c. of the urine with a solu- 
tion of 4 grammes of sodium hydrate in 1 litre of water. 
This decinormal alkaline solution is dropped from a 
burette into the urine until the latter becomes exactly 
neutral, as is indicated by its having no action on either 
red or blue litmus paper. Since 1 c.c. of the solution 
contains 4 milligrammes of sodium hydrate, the number 
of cubic centimetres used multiplied by 4, and by the 
number of 100 c.c. passed per day, expresses the daily 
acidity of the urine in milligrammes of sodium hydrate. 
The acidity may also be expressed as equivalent to a cer- 
tain quantity of crystallized oxalic acid, of which 1 c.c. 
of the sodium hydrate solution is equivalent to 6.3 milli- 
grammes. The acidity of the urine for twenty-four hours 
is equivalent to 1.6-2.4 grammes of crystallized oxalic 
acid. 
As has been said, the daily acidity of the urine is 
sufficient to neutralize from 1 to 1.5 grammes of sodium 
hydrate ; the mean daily excretion of uric acid is about 
5 decigrammes; this would be sufficient to neutralize 
about 24 centigrammes of sodium hydrate, supposing 
neutral urate to be formed. The daily excretion of 
hippuric acid rarely exceeds 3 decigrammes, a quantity 
which would not quite saturate 7 centigrammes of sodium ALKALINE URINE. 
93 
hydrate. It is thus seen that the uric acid and hippuric 
acid together could in any case only account for jVo or 
of the acidity of the urine. 
Now the daily elimination of acid phosphates corre- 
sponds to about 2.3 grammes of phosphoric anhydride ; 
to convert these phosphates into neutral salts of the 
formula R21IP04 would require 1.3 grammes of sodium 
hydrate. The mean daily acidity of the urine does not 
exceed this figure. A simple calculation, based upon 
analyses, thus shows that the acid phosphates alone are 
capable of fully accounting for the acidity of the urine, 
the greater part of these phosphates consisting of the 
acid phosphate of sodium, NaH2P04. 
§ 129. Alkaline urine.—As has already been men- 
tioned, normal urine becomes alkaline after standing 
some time, the urea being converted into ammonium car- 
bonate. This change is more rapid as the temperature 
is more elevated, or when blood or pus is present. Some 
urines which contain albumen and pus, are acid at the 
moment of micturition, but become alkaline in a few 
hours. It should not be concluded that a urine was 
alkaline when passed unless the test be applied imme- 
diately after micturition. 
Unless the alkalinity of a urine can be traced to diet 
or medicament, it is an unfavorable symptom ; it may be 
produced in the kidney when that organ is diseased, or 
the urine may become alkaline in the bladder. In this 
case it is generally turbid, thick, and even viscous at the 
moment of emission. 
The alkalinity is due to either sodium carbonate, 
sodium phosphate, or ammonia; in the former case, 
earthy phosphates are deposited a short time after the 
urine is voided; when the alkalinity is produced by the 
spontaneous formation of ammonium carbonate, ammonio- 
magnesium phosphate is also precipitated. 
Normal urine being acid, contains no free ammonia, 
and the alkalinity of an alkaline urine may readily be 
traced to its cause ; for this purpose, a small quantity of 
the urine is heated in a test-tube, and a moistened red 
litmus-paper is suspended a short distance above its sur- 
face. Should ammonia or ammonium carbonate be pre- 94 
URINE. 
sent, the paper will become blue, and a glass rod dipped 
in hydrochloric acid and held above the urine, will be 
surrounded by thick white fumes. 
If these results be not obtained, the alkalinity is due 
to an alkaline carbonate or phosphate. In the latter 
case, the urine is troubled by heat, but the cloud is 
readily dissolved on cooling and passing a stream of 
carbon dioxide through the liquid. 
§ 130. Color.—But little is known of the nature of 
the coloring matters of urine, and the cause of the yellow 
color of normal urine is not as yet understood. Healthy 
urine may have any of the shades of amber, and some- 
times has an orange tint. When large quantities of urine 
are eliminated, it is usually pale, or sometimes even 
colorless ; this is observed in disease, and after the in- 
gestion of much beer or wine, especially champagne. In 
certain affections the coloring matter of the blood or bile 
may pass into the urine ; the latter is then red, orange, 
greenish, brown, and sometimes nearly black. After 
poisoning by hydrogen arsenide, the urine is colored red 
by the presence of hematin. 
Hydrobilirubin has been detected in febrile urine, and 
normal urine contains indican (see § 106 and § 109). 
The detection of abnormal coloring matter will be indi- 
cated farther on (§§ 136-138). 
Detection of Abnormal Substances. 
ALBUMEN. 
§ 131. Albumen is one of the most important sub- 
stances that may appear pathologically in the urine, and 
a determination of its absence or presence is of great 
service in diagnosis. Normal urine contains no albumen, 
but in the affection known as Bright’s disease, in other 
renal affections, in certain fevers, and in some diseases 
of the spinal cord, more or less albumen is always pre- 
sent, and the gravity of the case may often be deter- 
mined by the proportion of that substance so eliminated. 
The general properties of albumen, and the means 
employed for its recognition, have already been de- DETECTION OF ABNORMAL SUBSTANCES. 
95 
scribed (§§ 76-78). The nitric acid test, indicated in 
§ 78, is conclusive, if the proper precautions be observed. 
The urine, contained in a test-tube, is acidified with one 
or two drops of acetic acid, and is then boiled for a few 
minutes. The formation of a cloud may be due to the 
separation of phosphates, or to the coagulation of a trace 
of albumen; the distinction is made by the addition of 
a few drops of nitric acid; phosphates would be redis- 
solved, while, unless an excess of nitric acid be employed, 
albumen will be unaffected. If much albumen be present, 
the entire mass of liquid may coagulate. 
By testing some of the precipitate with hydrochloric 
acid, as indicated in § 76, c, all doubt of its nature may 
be removed. 
The separation of albumen from its solutions by means 
of sodium sulphate has already been described (§ 79), 
as has also its detection by the use of an alcoholic solu- 
tion of phenol (§ 82, b~). 
In the application of any of these tests, the urine must 
be perfectly clear, and if it possess any turbidity, due to 
pus or the separation of sediment, it must be previously 
clarified by filtration. 
The application of the nitric acid test by pouring the 
urine upon the surface of nitric acid in a test-glass, and 
examination for turbidity at the line of contact of the two 
liquids, is untrustworthy and cannot be recommended. 
GLUCOSE. 
§ 132. It cannot be admitted that normal urine con- 
tains glucose, although but few specimens of urine can 
be found which do not reduce Fehling’s solution to a 
very slight extent. However, glucose is always present 
in the disease known as diabetes mellitus, and its quan- 
tity may then exceed even 100 grammes per litre. Dia- 
betic urine is generally pale in color, and has a high 
specific gravity (1030-1050) ; the daily excretion is 
usually increased to at least double the normal average, 
and in some cases may reach twenty litres. 
Urine containing albumen must always be freed from 
that substance before being tested for glucose ; this is 96 
URINE. 
accomplished by boiling the urine with a few drops of 
acetic acid, and filtration from the albumen precipitated; 
or the urine may be saturated with sodium sulphate, fil- 
tered, boiled, and again filtered to separate the coagulum; 
by this method, albumen and glucose may both be esti- 
mated quantitatively in the same portion of urine. Be- 
sides this, the urine employed should always be fresh. 
Glucose is then sought by one of the tests given in 
sections 21-24. Of all these tests, preference must be 
given to that by means of Fehling’s solution. The re- 
duction of the blue liquid takes place in the cold, as well 
as by the aid of heat, but is then much slower, several 
hours or even an entire day being required. 
If the urine contain only a small proportion of glucose 
(two or three grammes per litre), at least 1 c.c. must be 
added for every 5 c.c. of Fehling’s solution, and the 
mixture must be boiled during several minutes. The 
reduction may be rendered more rapid by previously 
boiling the urine with a solution of sodium hydrate ; 
much of the urea is thus decomposed and eliminated, and 
the liquid will be more prompt in its action on Fehling’s 
solution. 
In the application of the copper reduction test by 
Trommer’s method, Fehling’s solution, or in any other 
manner, the complete disappearance of the blue color, 
and its replacement by red or yellow, is indicative of 
the presence of glucose; the dark-red precipitate of 
cuprous oxide is not always formed, unless great care be 
taken, even though the reduction be perfect. 
When a non-albuminous urine is without action on 
Fehling’s solution, it may be safely concluded that no 
glucose is present. 
INOSITE. 
§ 133. Inosite has been found in the urine in a few 
cases, being sometimes associated with glucose, some- 
times with albumen. It can only be detected by sepa- 
rating it in a pure state, and applying the characteristic 
tests, as indicated in sections 26-28. DETECTION OF ABNORMAL SUBSTANCES. 
97 
LACTIC ACID (PARALACTIC). 
§ 134. Paralactic acid is said to be present in diabetic 
urine, and in urine containing an excessive proportion of 
either uric acid or calcium oxalate. However, it is 
rarely found in fresh pathological urine. Sohultzen has 
noticed that it appears in the urine after poisoning by 
phosphorus. 
To detect its presence, the urine is concentrated on a 
water-bath, the still warm liquid is mixed with 95 per 
cent, alcohol, and the alcoholic extract treated as directed 
in § 14. The paralactic acid is recognized by the cha- 
racters of its zinc salt. 
BILIARY ACIDS AND PIGMENTS. 
§ 135. Small quantities of the biliary acids sometimes 
pass into the urine ; for their detection, as large a quan- 
tity as possible (about 500 c.c.) of the urine is evapo- 
rated to dryness, the residue extracted with 85 per cent, 
alcohol, and the extract filtered. The alcohol is distilled 
off, and the new residue is exhausted with absolute alco- 
hol, the solution filtered, and again evaporated to dry- 
ness. The last residue, which is free from mineral salts, 
is dissolved in a little distilled wrater, and treated with 
ammonia and basic lead acetate, until the latter produces 
no further precipitate. In about twelve hours, the pre- 
cipitate is collected, washed with distilled water, pressed 
between folds of filter-paper, and boiled with alcohol. 
The liquid is filtered boiling,and the filtrate treated with 
sodium carbonate, which reacts with the lead salts of the 
biliary acids. The mixture is then evaporated to dry- 
ness and the new residue boiled with alcohol, which dis- 
solves the sodium compounds of the biliary acids. The 
alcoholic liquid is filtered, evaporated to dryness, and the 
residue extracted writh water. The solution thus obtained 
may be directly submitted to Pettenkofer’s test (§ 67). 
It is introduced into a small test-tube and mixed with 
two or three drops of a solution of one part of cane-sugar 
in four parts of water. Pure concentrated sulphuric acid, 
containing no sulphurous acid, is then added drop by drop 98 
URINE. 
until the liquid becomes somewhat heated, but the tem- 
perature should not be allowed to rise too high. The 
presence of biliary acids is indicated by a turbidity 
which soon disappears, the liquid then becoming yelloAV, 
cherry-red, deep red, and finally violet or purple. The 
reaction may take place immediately, or, if too many 
precautions have been taken, may not become apparent 
until after the lapse of some time. 
§ 136. Normal urine contains no trace of biliary pig- 
ments, but in certain diseases these coloring matters pass 
into the blood and thence into the urine, which becomes 
dark yellow, brown, or green. Such urine generally 
yields an abundant, persistent froth when agitated, and 
produces dark stains on white filter-paper. 
The biliary pigments are detected by Gmelin’s test. 
The urine is introduced into a conical test-glass, and 
nitric acid containing nitrous acid in solution is allowed 
to flow slowly down the side of the glass, so that the 
liquids may not mix at once. Nitric acid which has be- 
come yellow by exposure to sunlight answers best for the 
purpose. If sufficient biliary pigment be present, colored 
zones will be formed at the bottom of the glass where the 
liquids have mixed, their colors being green, blue, violet, 
red, and yellow, in this order from above downwards. If 
bilirubin be present, the green appears first, and is then 
characteristic. 
Gmelin’s test is very delicate, and may be rendered 
more so by operating as follows : 2 or 3 cubic centi- 
metres of pure nitric acid and one drop of nitric acid 
charged with nitrous acid, are introduced into a test-tube, 
and the urine is allowed to flow slowly upon the surface 
of the acid by the aid of a pipette. The colored zones 
may then appear simultaneously, or successively in the 
order given above. The urine tested should contain no 
alcohol, but the presence of albumen does not affect the 
sensitiveness of the test. 
When mixed with hydrochloric and acetic acids, urine 
containing biliprasin produces a green color which changes 
to brown when the liquid is neutralized by ammonia. Most 
icteric urines produce this reaction. 
§ 137. Red hepatic urine.—This name is applied by DETECTION OP ABNORMAL SUBSTANCES. 
99 
Mdhu to urine which assumes a violet-red color when 
mixed with two or three times its volume of hydrochloric 
acid; such urine behaves in the same manner with sul- 
phuric acid, hut nitric acid produces a mahogany or 
hyacinth-red. Urine possessing these properties is not 
unfrequently encountered. According to Mdhu, its color- 
ing matter is derived from the liver, and it seems probable 
that it may be hydrobilirubin in a more or less altered 
condition. He separates the pigment, as well as other 
biliary pigments which may be present, by acidifying the 
urine with about one gramme of sulphuric acid per litre, 
and then saturating the acid liquid with ammonium sul- 
phate. When no more ammonium sulphate dissolves, the 
liquid is filtered, and the filtrate will be nearly colorless, 
while the pigment will remain upon the filter, having a 
brownish-yellow color. As it is soluble in water, it is 
dried without washing, and may be extracted by absolute 
alcohol. 
If the mixture of urine and ammonium sulphate be 
allowed to stand, flakes of pigment separate and either 
remain floating near the surface of the liquid or are in 
great part deposited. 
It may be remarked, with regard to this method of 
Mdhu, that comparatively few samples of urine can be 
found in which more or less of a yellowish coloring matter 
is not precipitated by saturating them with ammonium 
sulphate, while at the same time the color of the liquid 
is much lightened. It is therefore of importance that 
the precipitate which may be obtained from normal urine 
should be studied before applying the test to abnormal 
urine. 
Harley recommends, for the detection of abnormal 
coloring matter derived directly from the blood, that the 
urine be boiled, acidulated with nitric acid, and when 
cold agitated with ether; the ether removes the coloring 
matter, and separates with a red color or wine-tint. 
The indications which may be deduced from these tests 
for coloring matter, are exceedingly unsatisfactory ; the 
presence of biliary pigments alone being of real diag- 
nostic value. It may generally be assumed, however, 
that a urine whose color is greatly intensified by the 100 
URINE. 
addition of nitric or hydrochloric acid, is not normal, but 
the cause Avill usually be a matter of speculation, unless 
a quantitative analysis be made for the estimation of 
urea, chlorides, phosphates, and all of the constituents 
whose proportions may be indicative of alteration in the 
processes of disassimilation. 
§ 138. Blue and violet urine.—Sometimes urine has 
a blue or violet color, which may appear either through- 
out the whole liquid, cr only on its surface, or bn the 
surface of the vessel containing it. This coloring matter 
is more commonly found in stale urine, and will usually 
be left on the filter-paper when the liquid is filtered. 
When such urine is agitated with ether or chloroform 
the coloring matter is taken up by the reagent, which 
separates with a rose, violet, or blue tint; if the urine 
be previously filtered, the blue coloring matter generally 
remains on the filter, so that the ether or chloroform as- 
sumes only a light rose-color. 
The nature of the red coloring matter, which is usually 
present writh the blue in these cases, is not known, for it 
only occurs in very minute quantities, its coloring pro- 
perties being very intense. 
The blue matter seems to be. identical with indigotine, 
and to be formed from the indican naturally existing in 
the urine (see § 110). It is highly probable that the 
red coloring matter is also derived from indican, for the 
latter decomposes into indigotine and a red matter called 
indirubin, which has already been mentioned (§ 112). 
CYSTINE. 
§ 189. Cystine is seldom found in the urine ; when it 
exists there, it is generally deposited as sediment soon 
after the urine is voided, hut occasionally it may remain 
dissolved for some time. Urine containing cystine is 
usually of a pale, sometimes a greenish color, and often 
possesses the odor of hydrogen sulphide. Urine having 
such an odor should be examined for cystine, and may 
lead to a diagnosis of cystic vesical calculus. Cystine 
is precipitated from urine on the addition of acetic acid, 
and may then be recognized by its crystalline form under DETECTION OF ABNORMAL SUBSTANCES. 
101 
the microscope, and by its chemical tests (§ 74). Before 
applying the lead oxide and potassium hydrate test, any 
albumen present must be removed from the urine, for 
albuminoid matters contain sulphur, and would produce 
a black precipitate when boiled with an alkaline solution 
of lead oxide. 
LEUCINE AND TYROSINE. 
§ 140. These substances are seldom present in urine, 
hut are almost invariably found in cases of acute atrophy 
of the liver, and sometimes in such abundance that a drop 
of the urine placed upon a microscope slide will solidify 
in a mass of crystals of leucine and tyrosine. They have 
also been found in the urine in fevers of a typhoid charac- 
ter. In such cases but little urea is present, albuminoid 
substances seeming to be eliminated principally in the 
form of leucine and tyrosine. 
Fig. 27. 
Tyrosine deposited from urine. 
Sometimes the tyrosine separates as sediment; it is 
then recognized by its microscopic appearance (Fig. 27) 
and by the characters described in § 62. 
To detect leucine and tyrosine dissolved in urine, the 
latter is freed from albumen, treated with basic lead 
acetate, the precipitate separated, and the liquid freed UKINE. 
from lead by means of hydrogen sulphide. The clear 
liquid, concentrated on a water-bath, gradually deposits 
tyrosine, which is purified by solution in boiling water, 
and recrystallization. The characters of tyrosine are 
described in § 62. 
Leucine is obtained from the mother-liquor from which 
tjrosine has deposited ; this is concentrated, and treated 
first with cold and then with boiling absolute alcohol, as 
long as the latter dissolves anything ; the brown residue 
will still contain tyrosine. The alcoholic extracts are 
united, evaporated to a syrupy consistence, and allowed 
to crystallize. After several days a granular deposit 
forms, consisting of crystals of leucine mixed with fatty 
matters. These are collected, pressed betwreen folds of 
filter-paper, dissolved in ammoniacal water, and basic 
lead acetate is added to the solution as long as it pro- 
duces a precipitate. The latter is a compound of leucine 
and lead oxide; it is collected on a filter, washed with a 
little water, then suspended in water and decomposed by 
hydrogen sulphide. When sufficiently concentrated, the 
filtered liquid deposits crystals of leucine. These are 
examined according to § 61. 
If the urine be stale, it will contain no leucine, that 
body being then converted into ammonium valerate. 
BLOOD. 
§ 141. Urine containing blood is dark in color, some- 
times red, sometimes brown, and sometimes even blackish. 
Three cases may be presented: 1st, the blood may be 
present as such, and red corpuscles will then be found on 
a microscopic examination of the sediment; 2d, no cor- 
puscles may be present, but the natural coloring matter 
of the blood, hemoglobin, can be detected ; 3d, the de- 
composition may have gone so far that only hematin can 
be recognized. In the latter two cases, the aid of the 
spectroscope is required to clearly demonstrate the pre- 
sence of the coloring matter of blood (§§ 87-88). In 
the first case, the microscope gives, satisfactory evidence. 
All urine containing blood also contains albumen, and the 
latter may be detected as already indicated. The red QUANTITATIVE ANALYSIS OF URINE. 
103 
corpuscles retain their characteristic form for some time 
in acid urine, but, if the latter be alkaline, they are 
rapidly destroyed (see § 183). 
AMMONIA. 
§ 142. The presence of ammonium carbonate in urine 
is detected according to section 129. It must be borne 
in mind that stale urine will always contain more or less 
ammonium carbonate, formed by the decomposition of 
urea. 
Rapid Qualitative Analysis of TTrine. 
§ 143. It is sometimes desirable to make a rapid 
chemical analysis of urine, such as may be practised at 
the bedside of a patient; in such a case, the physical 
characters are first observed ; the color, transparence, 
odor, reaction, specific gravity ; if any sediment be pre- 
sent, this must be subsequently examined microscopically. 
Portions of the urine are then tested : — 
1. For albumen, by the nitric acid test. 
2. For glucose ; the specific gravity will generally 
have indicated whether it be important to make this test. 
3. Biliary acids by Pettenkofer’s test, and biliary 
pigments by Gmelin’s test. Pettenkofer’s test seldom 
succeeds when thus applied directly to the urine. 
While such a brief examination can never be accepted 
as conclusive, yet it will frequently be of service, as it 
may show that the urine is normal, or that a more care- 
ful chemical examination is necessary. 
Quantitative Analysis of Urine. 
ESTIMATION OF NORMAL CONSTITUENTS. 
§ 144. The quantitative analysis of urine is under- 
taken for the determination of the proportions of the 
various constituents, normal or abnormal, which may be 
present. The methods which are employed are both 
gravimetric and volumetric, and the latter are always 104 
URINE. 
preferable when their results are equally trustworthy as 
those of the former; they are more rapid, and demand 
less expensive apparatus and less practice in manipula- 
tion. 
It has already been mentioned that the composition of 
the urine varies considerably with the hours of the day 
at which it is voided. For this reason, a quantitative 
analysis should be made upon a portion of the mixed 
urine of the twenty-four hours ; if this be impossible, the 
urine passed in the morning should be analyzed by pre- 
ference. In any case, the results should be so calculated 
as to express the proportions of the various constituents 
eliminated in twenty-four hours ; hence it is important 
that the daily volume of the excretion be known. 
Should any sediment be present, it is separated by 
filtration, and the quantitative operations conducted upon 
the filtrate. 
The following figures have been given as representing 
about the proportions of the various substances eliminated 
by the kidneys in twenty-four hours, and the centesimal 
composition of average normal urine. 
Water . 
Quantity in grammes 
eliminated per day. 
. 1238.07 
Composition of 
1 kilo, of urine. 
952.36 
Urea . 
31 55 
24.27 
Uric acid 
0.52 
0.40 
Hippuric acid 
1.30 
1.00 
Creatinine 
1.30 
1.00 
Xanthine 
0.006 
0.004 
Pigment and ill-defined 
matters ... 
extractive 
7.065 
5.435 
Sodium chloride 
13.30 
10.231 
Alkaline sulphates 
4.03 
3.10 
Phosphates calcium 
0.408 
0.314 
magnesium . 
0.591 
0.455 
sodium 
1.86 
1.431 
* 
1300,000 
1000.000 
Water . . . . 
. 1238.07 
952.36 
Organic matter 
41.74 
32.11 
Mineral matter 
20.19 
15.53 
1300.00 
1000.00 ESTIMATION OF WATER. 
105 
§ 145. Weigh 10 c.c. of the urine in a platinum cap- 
sule or porcelain crucible, the weight of which has already 
been determined, and evaporate to dryness in a hot-water 
oven at 100°, until the weight of the residue remains 
sensibly constant. As this residue is quite hygroscopic, 
the capsule should be covered during the weighing. The 
difference between the weight of the urine and that of 
the residue is the weight of water contained in IOjC.c. of 
the urine ; the weight of the residue is the total fixed 
matter, organic and mineral. The residue is now incine- 
rated at a red-heat over a Bunsen burner or an alcohol 
lamp. The residue consists of the fixed mineral matters; 
the difference between the weight of this latter and that 
of the total fixed matter, is the weight of the solid organic 
matter contained in the 10 c.c. 
This method yields only approximate results; in cer- 
tain cases it may be accurate, but, since few specimens 
of urine can be evaporated without decomposing a con- 
siderable proportion of the urea present, it can readily 
be understood that the method has but little real value. 
However, it may be used for the estimation of the inor- 
ganic constituents ; should the urine be poor in solid 
matters, a fact at once indicated by a low specific gravity, 
it may be necessary to evaporate 20, 50, or even 100 
c.c., instead of 10 c.c., which is generally sufficient for 
healthy urine. 
Magnier de la Source recommends that about 2 c.c. of 
urine be accurately weighed between two watch-glasses, 
and evaporated at the ordinary temperature in a vacuum. 
In twenty-four hours the dry residue may be weighed, 
and the quantities of water and of fixed matter can be 
calculated. This method appears to give very accurate 
results, the figures given by the author being quite satis- 
factory. 
Neubauer proposed a method for the calculation of the 
fixed matter from the specific gravity, and the approxi- 
mation is very close in the case of normal urine ; for 
pathological urine, however, its results are not so trust- 
worthy. It consists in multiplying the last two figures 
ESTIMATION OF WATER AND OF FIXED MATTERS. 106 
URINE. 
of the observed density by the constant factor 2.33 ; 
thus were the specific gravity 1024 (24 x 2.33 = 55.92), 
1000 parts of urine would contain 55.92 parts of solid 
constituents. This approximate calculation is sufficiently 
accurate for the purposes of physicians. 
.The presence of the alkaline and earthy metals, and 
of the mineral acids with which they are combined, may 
be detected in the residue of the last incineration by the 
usual chemical tests. 
Normal urine contains from 40 to 65 grammes of solid 
matter per litre, of which between one-fifth and one-tliird 
is composed of anhydrous mineral salts. 
I. —Organic Constituents. 
UREA. 
§ 146. A healthy adult man excretes from 15 to 30 
grammes of urea per day; women eliminate somewhat 
less. 
Numerous methods have been devised for estimating 
the proportion of urea contained in urine ; of these, two 
are quite trustworthy, while their application is easy, 
and either of them may be employed. 
§ 147. Liebig’s method depends upon the precipi- 
tation of the urea by a solution of mercuric nitrate of 
known strength (see § 39). 
The reagents and apparatus required are— 
1st. A titrated solution of mercuric nitrate, of which 
1 c.c. corresponds to exactly 10 milligrammes of urea. 
2d. A baryta solution, made by mixing two volumes 
of cold saturated baryta-water with one volume of a cold 
saturated solution of barium nitrate. 
3d. A rather strong solution of sodium carbonate. 
4th. A burette of 50 c.c. capacity. 
5th. A volume pipette of 15 c.c. capacity. 
Preparation of the solution of mercuric nitrate.—a.— 
4 grammes of pure urea, dried over sulphuric acid in a 
vacuum, are dissolved in distilled water, and the solution 
is diluted to exactly 200 c.c. 10 c.c. of this solution 
contain 200 milligrammes of urea. ESTIMATION OF UREA. 
107 
b.—96.855 grammes of perfectly dry and chemically 
pure mercuric chloride are dissolved in distilled water, 
and a dilute solution of sodium hydrate is added as long 
as it forms a precipitate. The latter is allowed to de- 
posit completely, the clear liquid is decanted, and the 
precipitate is washed with distilled water, first by de- 
cantation, then upon a filter. After the washing is 
terminated, the filter is pierced, and all of the precipitate 
is carefully Avashed into a flask or beaker; Avhen the 
mercuric oxide has subsided, the water is poured off,' 
and the mercuric oxide is dissolved in a sufficient quan- 
tity of nitric acid containing no nitrous acid. The solu- 
tion is diluted to nearly one litre, and its exact volume 
is measured. 
10 c.c. of the normal solution of urea (a) are meas- 
ured into a beaker, and into this liquid the solution of 
mercuric nitrate is allowed to Aoav from a burette (Fig. 
28), until a drop of the mixture, removed by the aid of 
a glass-rod, produces a distinct yellow color with a drop 
of sodium carbonate solution. The number of cubic 
centimetres of the mercury solution required to effect 
this reaction is read off exactly ; if the solution Avere 
exactly titrated, just 20 c.c. Avould have been employed, 
hut as it is thus far only approximate, the number will 
he someAvhat less than 20 c.c. The mercury solution is 
therefore diluted Avith exactly sufficient distilled Avater to 
make 20 c.c. equivalent to 10 c.c. of the urea solution. 
For example, if 19.25 c.c. of the approximate mercury 
solution be required to precipitate 10 c.c. of the urea 
solution, 0.75 c.c. of distilled water should he added for 
every 19.25 c.c. of the original solution, or 7.5 c.c. of 
Avater for every 192.5 c.c. of the mercury solution. If 
then the approximate solution measure 962.5 c.c., it 
must be diluted with 37.5 c.c. of Avater. If only 18 
c.c of the mercury solution were required, for every 
180 c.c., 20 c.c. of Avater must be added. 
After exactly diluting the mercury solution, its 
strength is confirmed by a neAV trial on 10 c.c. of the 
urea solution. Just 20 c.c. should be required to pro- 
duce the final reaction with sodium carbonate. The 
titrated solution is kept in Avell-stoppered bottles. 108 
URINE. 
Practice of the analysis.—The analysis by Liebig’s 
method requires that the phosphates shall be first com- 
Fig. 28. 
pletely precipitated from the urine ; this is accomplished 
by the baryta solution. 
A certain volume of the urine, say 40 c.c., is exactly 
measured, and mixed with half its volume, that would be ESTIMATION OF UREA. 
109 
20 c.c., of the baryta solution. The liquid is well mixed 
by stirring with a glass rod, and the precipitate is sepa- 
rated by filtration. 15 c.c. of the filtrate, which would 
correspond to 10 c.c. of the original urine, are measured 
into a beaker, and the normal solution of mercuric nitrate 
is allowed to flow in, drop by drop, from the burette, 
until a drop of the mixture, removed by the aid of a glass 
rod, produces a distinct yellow color with a drop of the 
sodium carbonate solution. This color is best seen upon 
a black surface, such as is obtained by placing a glass 
plate or watch-glass upon black glazed paper. 
The volume of the mercury solution used is then read 
off in cubic centimetres, and this number multiplied by 
ten gives the number of milligrammes of urea contained 
in 10 c.c. of the urine analyzed. 
Corrections.—This method only gives exact results 
in solutions containing 2 per cent, of urea; therefore, if 
more than 30 c.c. of the standard solution be required 
to precipitate the urea from the 15 c. c. of diluted urine 
employed, the mixture will contain more than two per 
cent, of urea, and it is then necessary, before the final 
trial with sodium carbonate, to add to the mixture a 
volume of distilled water equal to half the number of 
cubic centimetres of mercury solution used in excess of 
30 c.c. For example, if 50 c.c. of the standard solu- 
tion have been employed (50—30=20), 10 c.c. of dis- 
tilled water are added to the mixture. Otherwise the 
amount of urea indicated by the analysis will be less 
than that really present. 
If, on the contrary, the urine contain less than two 
per cent, of urea, the proportion of the latter will appear 
greater than it really is ; this error is corrected by sub- 
tracting from the number of cubic centimetres of the 
mercury solution used one-tenth of a cubic centimetre for 
every 5 c.c. less than 30 ; for example, if only 20 c.c. 
be required to produce the yellow color with sodium 
carbonate, two-tenths of a c.c. are subtracted, and 19.8 
c.c.xlO will express in milligrammes the quantity of 
urea present. 
If a large proportion of sodium chloride be present in 
the urine, the results by Liebig’s method will be too 110 
URINE. 
high, since mercuric chloride would then be formed, and 
this does not precipitate urea. If the proportion of 
sodium chloride he small, the error may be neglected, 
but, if it amount to 1 or 1.5 per cent., 2 c. c. are sub- 
tracted from the volume of mercury solution used to pre- 
cipitate 10 c.c. of urine. The result is then approxi- 
mately correct; but if an exact estimation of urea be 
required, the chlorides must first be precipitated by 
silver nitrate, as follows :— 
The 15 c.c. of prepared urine are exactly neutralized 
with nitric acid, and a drop or two of a saturated solu- 
tion of neutral potassium chromate is added. A solution 
of silver nitrate is then allowed to flow from a burette 
into the mixture, until the white precipitate at first 
formed assumes a distinct orange color. The titration 
by the solution of mercuric nitrate is then conducted in 
the liquid, as already directed, without removing the 
precipitated silver chloride. Of course, the increased 
volume of the original 15 c.c., due to the addition of the 
silver solution, must be borne in mind in making the first 
correction mentioned. 
§ 148. Yvon’s method.—This method depends upon 
the decomposition of the urea by sodium hypobromite, 
and the determination of the quantity of nitrogen set 
free (see § 38). Since the estimation of the nitrogen 
requires corrections for temperature and pressure, the 
process has been slightly modified, and rendered more 
rapid, by a comparison of the volume of nitrogen dis- 
engaged from a known quantity of the urine with that 
eliminated from a known quantity of urea at the time of 
the experiment. 
The apparatus and reagents i*equired are— 
1st. A ureometer (Fig. 29). This is a glass tube, 
about 40 centimetres long, divided into two unequal 
compartments by a glass stopcock. Each section of the 
tube is graduated into cubic centimetres and tenths of 
cubic centimetres, numbered from the stopcock. 
2d. A solution of urea containing 2 per cent, of urea, 
made by dissolving 4 grammes of perfectly dry pure urea 
in 200 c.c. of distilled water. 
3d. An alkaline solution of sodium hypobromite, pre- ESTIMATION OF UREA. 
111 
pared by dissolving 17 grammes of sodium hydrate and 
5 grammes of bromine in 183 c.c. of distilled water. 
A deep vessel, preferably of iron, nearly filled with 
mercury, and a tall jar of water into which the ureometer 
may be plunged up to the stopcock, will also 
be necessary ; the apparatus may be simplified 
and the process shortened by fitting a rubber 
cork and caoutchouc tube to the lower end of 
the ureometer, the extremity of the caoutchouc 
tube being adapted to any suitable glass mer- 
cury reservoir which may be raised and lowered 
on a support, as necessary. The ureometer 
is also clamped to the support in a vertical 
position. The operation will be described, 
supposing this latter arrangement to be adopt- 
ed ; the manipulation by the use of the deep 
mercury trough will then be self-evident. 
The anatysis is conducted upon 1 c.c. of 
urine. 
The stopcock of the ureometer being open, 
the mercury reservoir is raised until the mer- 
cury rises in the ureometer and exactly fills 
the lower portion. The stopcock is then closed, 
and the mercury reservoir is fixed at this level. 
10 c.c. of the urine are diluted with distilled 
water to exactly 50 c.c. 
5 c.c. of the normal solution of urea are 
poured into the upper compartment of the 
ureometer, the mercury reservoir is lowered, 
and, on opening the stopcock, the urea solu- 
tion will flow into the lower compartment. 
Care must be taken that no air enters, and, as 
soon as all of the solution has passed the stop- 
cock, the latter is closed. The upper com- 
partment is then washed out Avith two or three 
c.c. of rather dilute sodium hydrate solution, which is 
also allowed to flow into the lower part of the tube. 
The upper compartment is now completely filled with 
the hypobromite solution, and the latter is rapidly passed 
into the urine by opening the stopcock and depressing 
the mercury reservoir. If any air-bubbles be allowed 
Fig. 29. 112 
URINE. 
to enter, it will be necessary to recommence the whole 
operation. By alternately raising and lowering the 
mercury reservoir, the solutions become thoroughly 
mixed, and nitrogen collects in the tube. The 5 c.c. of 
urea solution used contained one centigramme of urea ; 
at 0°, and under a pressure of 760 millimetres, this 
would yield 3.5 c.c. of nitrogen. However, no atten- 
tion's paid to the temperature and pressure, but when 
the evolution of gas has ceased, the volume of nitrogen is 
read off, the mercury being brought to the same level in 
the ureometer and in the reservoir. 
The liquid is then removed from the ureometer by 
opening the stopcock, and raising the mercury reservoir: 
and the tube is thoroughly washed out with distilled 
water. After some practice in the manipulation, the 
washing may be done quite rapidly. 
The upper compartment is carefully dried by filter 
paper, and 5 c. c. of the diluted urine, containing 1 c. c. 
of urine, are introduced, and operated upon precisely as 
has been described for the urea solution. Then—- 
Vol. of N yielded by 
1 centigramme urea 
: 1 :: 
. Vo), of N yielded 
• by 1 c. c. of urine 
. No. of centigrammes of 
• urea iu J e. c. of urine. 
Example.— 5 c. c. of the normal solution of urea 
have produced 3.9 c.c., or 39 divisions, of nitrogen. 
At the same time, 5 c. c. of the diluted urine, containing 
1 c.c. of urine, have yielded 5.8 c.c., or 58 divisions, 
of nitrogen. Hence 1 c. c. of the urine contains f § cen- 
tigrammes of urea; or 1000 c.c. of urine contain 14.87 
grammes of urea. If it be desired to estimate the 
amount of urea in 1 kilogramme of urine, the quantity 
contained in one litre is multiplied by 1000 and divided 
by the specific gravity: thus if the density of the urine 
. l l a • i i m q 14-87x1000 
m the example already given be 1018, —— = 
14.607, the quantity of urea in 1 kilogramme of urine. 
Precautions.—The stopcock of the ureometer must 
be frequently greased, otherwise it will allow the en- 
trance of air. The sodium hypobromite solution does 
not keep well, especially in warm weather, and should be ESTIMATION OF UREA. 
113 
frequently renewed. If the proportion of urea be ex- 
tremely small (indicated by the specific gravity), the urine 
is not diluted, and two, three, or even five c. c. are em- 
ployed. If, on the contrary, the proportion of urea be 
very great, it may be necessary to limit the analysis to 
half a cubic centimentre ; in this case 5 c. c. are diluted 
to 100 c. c. and 5 c. c. of the diluted urine are employed 
as before. 
This method is quite accurate, and sufficiently rapid: 
the entire operation may be concluded in fifteen or 
twenty minutes. The ureometer must be thoroughly 
washed with water or dilute hydrochloric acid, after 
each operation. 
§ 149. Esbach’s method.—This method also depends 
upon the decomposition of urea by sodium hypobromite, 
but the apparatus is much simpler, and the operation 
more rapid than in Yvon’s process. The only apparatus 
required is a stout glass tube about 40 centimetres long, 
closed at one end, and containing about 28 c. c. It is 
graduated, beginning at the closed end, in cubic centi- 
metres, and tenths of cubic centimetres. 
A normal solution of urea, and a sodium hypobromite 
solution are required. These are prepared precisely as 
in Yvon’s process. 6 c. c. of the sodium hypobromite 
solution are poured into the tube, and about 8 c.c. of 
water are carefully added, so that the two liquids may 
not mix. The volume of liquid is then read, say 14.7 c. c. 
By the aid of a pipette, exactly one cubic centimetre of 
the urine to be examined is introduced, being allowed to 
flow down the sides of the tube, and the latter is imme- 
diately closed by the thumb protected by a piece of sheet 
caoutchouc, or by a caoutchouc cork, and vigorously 
agitated. The volume of liquid in the tube is equal to 
the initial volume plus 1 c.c., say 15.7 c.c. When no 
more gas is disengaged, the open extremity of the tube, 
is plunged into water, and the thumb removed, or the 
caoutchouc stopper withdrawn. A quantity of liquid is 
then expelled equal in volume to that of the nitrogen set 
free. The tube is then depressed in the water until the 
level of the interior liquid coincides with that of the 
water in the exterior vessel; the extremity is again 114 
URINE. 
closed by the thumb or a caoutchouc cork, and the in- 
strument is withdrawn, held vertically with the closed 
extremity down, and the volume of liquid read off. The 
difference between this reading and the total volume of 
liquid used, gives the volume of nitrogen formed. If, 
for example, 9.3 c. c. of liquid remain, 15.7 — 9.3 —6.4, 
the nitrogen eliminated by 1 c. c. of urine. 
The operation is repeated in the same manner, the 1 
c. c. of urine being replaced by 5 c. c. of the normal 
urea solution ; the volume of nitrogen generated is de- 
termined by the volume of liquid it expels, and the sub- 
sequent calculations are made precisely as in Yvon’s 
process. 
This method is very rapid, and sufficiently accurate. 
If the ureometer be closed, by the thumb, the latter 
should be blown upon horizontally before removing it 
for the final reading, in order that adhering water may 
not run into the tube. If a caoutchouc cork he em- 
ployed, this must always be inserted to the same point. 
URIC ACID. 
§ 150. The quantity of uric acid excreted, is as varia- 
ble in health as in disease, ranging from 0.3 to 0.8 
gramme per day. The average amount is about 5 deci- 
grammes ; it is much increased by an animal diet, and 
correspondingly diminished when but little nitrogenized 
food is taken. 
The proportion of uric acid present in urine can only 
be determined, with any degree of accuracy, by the bal- 
ance. If albumen be present, the urine must first be 
boiled, rendered freely acid with acetic acid, and filtered 
boiling. In any case, it must be filtered to separate 
mucus and other suspended matters. From 200 to 400 
c. c. of the clear, filtered urine, are then mixed with 
three or four per cent, of concentrated hydrochloric acid, 
and the mixture is allowed to stand in a cool place for 
twenty-four or forty-eight hours. The uric acid then 
separates in the crystalline form. The operation should 
be performed in a vessel which may be easily cleaned by 
the fingers, since the crystals sometimes obstinately ad- ESTIMATION OF URIC ACID. 
115 
here to the sides of the vessel. The precipitated acid is 
collected on a tared filter, the glass rinsed with 5 or 10 
c. c. of distilled water to wash the uric acid into the filter, 
and any crystals still remaining are removed by the 
finger and washed into the filter with a little alcohol. 
The glass should be washed with alcohol until no crys- 
tals can be seen by the aid of a magnifying glass. All 
of the washings are passed through the filter. The latter, 
with its contents, is dried at 100°, and weighed between 
two watch glasses. (Fig. 30.) 
Fig. 30. 
This method is not absolutely accurate, nor is any 
other for the estimation of uric acid, for a small quantity 
of the latter is lost by its slight solubility in acid urine, 
and with the water used for washing. The quantity of 
the latter should be limited, if possible, to about 10 c. c. 
If, however, more than 30 c.c. be employed, .045 milli- 
gramme are added to the weight of uric acid found, for 
every cubic centimetre of water in excess of 30. (Neu- 
bauer.) If, for example 55 c. c. of wash water be used, 
55—80 = 25 x .045 = 1.125 milligrammes must be added 
to the amount of uric acid found by the balance. 
On the contrary, the precipitated uric acid always re- 
tains some coloring matter, and the latter compensates, 
in a measure, for the necessary loss, unless, as has been 
said, the precipitate be washed with more than 30 c. c. 
of water. 
HIPPURIC ACID. 
§ 151. The amount of liippuric acid eliminated by the 
kidneys, seldom exceeds 8 or 4 decigrammes in twenty- 
four hours, unless certain vegetable medicaments or vege- 116 
URINE. 
table aliments be ingested. Consequently, large quantities 
of urine are required for the estimation of this acid. It 
may be separated by the following process, proposed by 
Meissner. One litre of fresh urine is completely pre- 
cipitated by baryta “water, and the excess of baryta is 
thrown down by dilute sulphuric acid, carefully avoiding 
an excess. The filtered liquid is exactly neutralized 
with hydrochloric acid, and evaporated to a syrupy con- 
sistence on a water-bath. The residue is agitated with 
150 or 200 c. c. of absolute alcohol, which dissolves the 
hippurates, and leaves the chlorides, etc., undissolved. 
The clear alcoholic solution is decanted, evaporated to a 
syrupy consistence, and rendered strongly acid by hydro- 
chloric acid. It is then agitated with 100 or 150 c. c. 
of alcoholic ether, which dissolves the hippuric acid, and 
leaves it in an impure state on evaporation. It is puri- 
fied by boiling with a small quantity of milk of lime, de- 
colorizing by animal charcoal, filtering the solution while 
boiling, and adding hydrochloric acid to the still hot fil- 
trate. The hippuric acid deposits in needles as the 
liquid cools. It is then collected, dried, and weighed. 
As hippuric acid is not very soluble in ether, a suffi- 
ciently large quantity of alcoholic ether must be em- 
ployed to effect its solution after it is first deposited. 
CREATININE. 
§ 152. A healthy adult excretes from 6 to 16 deci- 
grammes of creatinine per day ; the quantity is diminished 
by a vegetable diet, and correspondingly increased by an 
exclusively animal alimentation. 
200 or 300 c. c. of the urine, free from albumen, are 
rendered alkaline by milk of lime, and treated with cal- 
cium chloride as long as the latter forms a precipitate. 
After one or two hours the liquid is filtered, the precipi- 
tate washed, and the filtrate, together with the washings, 
rapidly evaporated to a syrupy consistence on a water- 
bath. The still warm liquid is agitated with 40 or 45 c. c. 
of 95 per cent, alcohol, and the mixture is poured into a 
glass, and allowed to stand in a cool place for six or 
eight hours. The liquid is then filtered through a very ESTIMATION OF SODIUM CHLORIDE. 
small filter, and the precipitate is washed with a little 
alcohol, which is added to the filtrate. If the total vol- 
ume of liquid exceed 60 c. c., it is reduced to 50 or 60 
c. c. by evaporation on a water-bath, and when quite 
cold, half a cubic centimetre of a concentrated and neu- 
tral alcoholic solution of zinc chloride is added, and the 
mixture briskly agitated. It is then allowed to stand in 
a cool place for two or three days, in which time the 
double compound of creatinine and zinc chloride separates 
in small crystals. The latter are collected on a small, 
tared filter, allowed to drain, and washed with a little 
alcohol, until the latter passes through colorless, and 
yields no precipitate with silver nitrate. The filter with 
its precipitate is then dried at 100°, and weighed. (Neu- 
bauer. 
100 parts of the double chloride of zinc and creati- 
nine correspond to 62.44 parts of creatinine. 
II. Mineral Constituents. 
SODIUM CHLORIDE. 
§ 158. The quantity of sodium chloride contained in 
the urine is extremely variable, depending, as is evident, 
on the state of the health and the nature and quantity of 
food taken. It ordinarily forms about two-thirds of the 
total fixed salts, or ash, and it seems that the daily elimi- 
nation may be comprised between five and twelve 
grammes. It is usual to determine the quantity of 
chlorine contained in the urine, and to estimate the 
entire amount as sodium chloride; the daily elimination 
of chlorine would then be from 3 to 7 grammes, repre- 
senting from 5 to II grammes of sodium chloride; the 
average excretion is nearer the latter figure. 
Solutions of chlorides and of phosphates are both 
precipitated by silver nitrate, but if a drop or two of 
potassium chromate solution be introduced into a liquid 
containing chlorides and phosphates, and silver nitrate 
then be added, it is found that red silver chromate is 
formed as soon as the chlorides are entirely precipitated, 
while the phosphates remain in solution until all of the 
potassium chromate is decomposed. 118 
URINE. 
The chlorine contained in urine may hence he volu- 
metrically estimated by a standard solution of silver 
nitrate. This is prepared by dissolving 29.065 grammes 
of pure, fused silver nitrate in distilled water, and 
diluting the solution to exactly one litre. One cubic 
centimetre of this solution corresponds to 10 milli- 
grammes of sodium chloride, or to 6.068 milligrammes 
of chlorine. 
10 c.c. of the urine are mixed with 2 grammes of pure 
potassium nitrate, and cautiously evaporated to dryness 
in a platinum or porcelain capsule: it is better that this 
evaporation should be conducted on a water-bath. The 
residue is then carefully heated until it fuses, and all 
traces of carbonaceous matter have disappeared. The 
cold mass is dissolved in about 80 c.c. of distilled Water, 
and the liquid is transferred to a beaker glass, and 
slightly acidified by a drop or two of dilute nitric acid: 
after which the excess of acid is saturated, and the 
solution rendered neutral, by the addition of a little pure 
calcium carbonate. A few drops of a saturated solution 
of potassium neutral chromate are added, and the silver 
nitrate is dropped into the mixture from a burette filled 
to the zero division, until the precipitate formed assumes 
a distinct orange color, which is persistent, and does not 
disappear on agitation. The number of cubic centimetres 
of the silver solution used, multiplied by 10, expresses 
in milligrammes the quantity of sodium chloride con- 
tained in 10 c.c. of the urine analyzed. Suppose 9.8 c.c. 
of the silver nitrate solution be required to produce the 
persistent tint of silver chromate: then 10 c.c. of the 
urine contain 9.8 X10 = 98 milligrammes of sodium 
chloride, and 1000 c.c. of the urine contain 9.8 grammes 
of sodium chloride, or 9.8 X 6.068 x 100 = 5.946 
grammes of chlorine. 
During febrile conditions of the system, the proportion 
of sodium chloride in the urine is much diminished, and 
gradually becomes normal with returning health. 
§1 154. Phosphoric acid exists in the urine as sodium 
acid phosphate, magnesium acid phosphate, and calcium 
PHOSPHORIC ACID, PHOSPHATES. ESTIMATION OF PHOSPHATES. 
119 
acid phosphate. The quantities of these salts eliminated 
per day, varies considerably, their sum generally corre- 
sponding to between one and two and a half grammes of 
phosphoric anhydride. The following figures have been 
given as representing the daily urinary excretion of the 
phosphates, expressed in phosphoric anhydride:— 
As sodium acid phosphate . . . 1.5 grammes. 
As magnesium acid phosphate . . . 0.(3 “ 
As calcium acid phosphate . . . 0.2 “ 
The sodium salt is soluble, but the solubility of the 
others is due to the acid character of the urine, and 
when the latter becomes alkaline, they are deposited. 
It is usual to estimate separately the total phosphoric 
acid, and that existing as earthy phosphates, that present 
as alkaline phosphates being estimated by difference. 
The most convenient method for the estimation of 
phosphoric acid is volumetrically, by precipitation as 
uranium phosphate, a standard solution of uranium 
acetate being used. 
In addition to a burette and volume pipette, the 
following solutions will be required. 
1st. A solution of sodium acetate, made by dissolving 
100 grammes of sodium acetate, and 100 c.c. of concen- 
trated acetic acid in distilled water, and diluting to one 
litre. 
2d. A solution of sodium phosphate, of which 50 c.c. 
shallcorrespond to exactly 0.1 gr.of phosphoric anhydride. 
This is made by dissolving 10.085 gr. of pure crystallized 
sodium phosphate (Na2lIP04 + 121120) in 1000 c.c. 
of distilled water. 
3d. A solution of uranium acetate, made by dissolving 
about 35 grammes of uranium acetate in distilled water, 
adding about 5 c.c. of strong acetic acid, and diluting 
the whole to one litre. As this solution generally 
deposits a precipitate, it should be allowed to stand some 
time before being titrated. 
50 c.c. of the sodium phosphate solution are measured 
into a beaker, and 5 c.c. of the sodium acetate solution 
added. The mixture is then stirred and heated to 90 or 
100°, preferably on a wTater bath. A burette is filled 120 
URINE. 
with the uranium acetate solution, and the latter is 
allowed to flow gradually into the hot sodium phosphate, 
with continual stirring, until a drop of the liquid, 
removed by the aid of a glass rod, produces a reddish- 
brown color when placed on some powdered potassium 
ferrocyanide, or in a drop of a strong solution of the 
latter salt. The number of cubic centimetres of the 
uranium solution used is now read off', and its exact 
strength is calculated. Suppose 20.5 c.c. of uranium 
solution to be required to produce the final reaction with 
potassium ferrocyanide. Since the 50 c.c. of sodium 
phosphate solution corresponds to 0.1 gr. of phosphoric 
anhydride, one cubic centimetre of the uranium solution 
will be equivalent to = .00487 gr. of phosphoric 
anhydride. The uranium solution is so prepared that 
each cubic centimetre shall precipitate 5 milligrammes 
of phosphoric acid; if its strength be found greater than 
this, the calculated amount of distilled water is added, 
but if more than 20 c.c. be required for 50 c.c. of the 
normal solution of sodium phosphate, the liquid may be 
used as it is, its exact strength being found as above. 
Analytical process.—The analysis must be performed 
precisely as the titration of the uranium solution. 50 c. c. 
of the filtered urine are mixed with 5 c.c. of the sodium 
acetate solution, heated nearly to boiling, and the 
uranium acetate is added, drop by drop, from a burette, 
until a drop of the liquid produces a reddish-brown color 
with potassium ferrocyanide. The urine must be kept 
hot, and the termination of the reaction is best detected 
by distributing twenty or thirty drops of potassium ferro- 
cyanide solution on a porcelain plate, before beginning 
the analysis, and touching these successively with drops 
removed from the urine under examination, after the 
addition of every J c.c. of the uranium solution. The 
number of c. c. of the latter solution used, multiplied by 
the equivalence of 1 c.c. in phosphoric anhydride, as 
already determined, gives the amount of phosphoric 
anhydride in 50 c.c. of the urine. 
Estimation of the phosphoric acid present as earthy 
phosphates.—200 c.c. of the urine are rendered strongly ESTIMATION OF SULPHURIC ACID. 
121 
alkaline by ammonia, and allowed to stand twelve hours. 
The precipitate of earthy phosphates is then collected on 
a small filter, Avashed with ammonia water, and trans- 
ferred to a beaker by piercing the filter and washing the 
precipitate through the opening by the aid of a wash- 
bottle. It is then dissolved in as small a quantity of 
acetic acid as possible, and, after the addition of 5 c.c. 
of the sodium acetate solution, the liquid is diluted to 50 
c.c. with distilled water, and titrated with the uranium 
solution as before. The result of the analysis gives the 
amount of phosphoric anhydride corresponding to the 
earthy phosphates in 200 c.c. of the urine. 
The proportion of phosphoric anhydride existing as 
alkaline phosphates is estimated by deducting that de- 
termined as earthy phosphates from the total amount 
found in the urine. 
§ 155. An adult man normally eliminates alkaline sul- 
phates corresponding to between two and three grammes 
of sulphuric acid daily. If it be desired to estimate 
accurately the quantity excreted, about 100 c. c. of the 
urine should be evaporated to dryness, after the addition 
of about 20 grammes of potassium nitrate, and the resi- 
due should be heated until all carbonaceous matter has 
disappeared. The mass is then dissolved in dilute hydro- 
chloric acid, and the solution is precipitated boiling with 
barium chloride. The precipitated barium sulphate is 
collected on a filter, washed with hot water, dried, and 
weighed. 100 parts of barium sulphate correspond to 
42.06 parts of sulphuric acid. 
It is seldom required to estimate sulphuric acid in the 
foregoing manner; Vogel places the average daily ex- 
cretion at about 2 grammes, and proposed the following 
approximate method for determining whether more or 
less than that quantity is eliminated. It is of course 
necessary, as in all other urinary estimations, that the 
daily volume of urine shall be known ; if this amount to 
1200 cubic centimetres, and the normal excretion of sul- 
phuric acid be 2 grammes, 60 c.c. of urine should contain 
ll 
SULPHURIC ACID. 122 
URINE. 
0.1 gramme of the acid. In such a case, 60 c.c. of the 
urine are acidified with hydrochloric acid, and a solution 
of barium chloride containing exactly sufficient of the 
salt to precipitate 0.05 gramme of sulphuric acid, is 
added. The mixture is then filtered, and a drop of 
barium chloride is added to the filtrate ; if no turbidity 
be produced, the daily excretion of sulphuric acid does 
not exceed one gramme ; but if a precipitate form, a 
quantity of barium chloride equal to the first is added, 
the mixture is filtered, and the new filtrate is tested with 
barium chloride. If a precipitate be again formed, more 
than two grammes of sulphuric acid are eliminated in 
twenty-four hours. 10 c.c. of a solution made by dis- 
solving 8.76 grammes of pure, dry barium chloride in 
one litre of water, will exactly precipitate 5 centigrammes 
of sulphuric acid. 
Estimation of Abnormal Constituents. 
ALBUMEN. 
§ 156. The proportion of albumen present in urine 
can only be accurately determined by coagulation, and 
drying and weighing the precipitate. A convenient 
method by which the coagulation may he accomplished 
has been described in section 84. The chief difficulty 
experienced when the coagulation is effected by heat, is 
caused by the obstinacy with which the coagulum ad- 
heres together and resists washing. This may be ob- 
viated, in a measure, by operating as follows: 20, 50, 
or 100 c. c. of the filtered urine, according to the pro- 
portion of albumen present, is gently heated, and as soon 
as it begins to appear clouded, a drop or two of acetic 
acid is added. The albumen then precipitates in large 
flakes; when the coagulation appears complete, the 
coagulum is collected upon a filter which has been 
dined at 110° and weighed, and is washed, first with 
hot water, then ivith alcohol. After sufficient draining, 
the filter and contents are dried at 100° in an air oven, 
until no further diminution of weight is perceptible. If 
a very exact estimation be required, the weight of the ESTIMATION OF GLUCOSE. 
123 
filter-ash should be known, and after the weight of the 
dried albumen has been found, the filter and contents 
should be thoroughly incinerated in a crucible, and the 
weight of the remaining mineral salts deducted from that 
of the precipitated and dried albumen. 
As has already been indicated, any albumen present 
must be removed from the urine before quantitatively 
estimating urea, uric acid, sodium chloride, or phos- 
phoric acid. This may be accomplished by heating the 
urine in a long-necked flask, so that it may not become 
more concentrated by evaporation, and performing the 
analytical operations upon a measured volume of the 
filtered liquid. 
GLUCOSE. 
§ 157. The most trustworthy process for the estima- 
tion of glucose depends upon the reduction of a cupric 
solution. As has already been mentioned (§ 22), when 
glucose is boiled with an alkaline solution of cupric 
oxide, the latter is reduced to cuprous oxide, and it has 
been found that one molecule of glucose is capable of 
reducing five molecules of cupric oxide, that is, 180 
parts of glucose reduce the cupric oxide contained in 
1247.5 parts of crystallized cupric sulphate. 
The cupric solution used is that proposed by Fehling, 
and is made as directed in section 33. Each c. c. con 
tains 34.64 milligrammes of cupric sulphate, and is ex 
actly reduced by 5 milligrammes of glucose. This solu- 
tion is fit for quantitative analysis only when it deposits 
no precipitate after being boiled and allowed to stand 
about half an hour. 
When the specific gravity of the urine, and a prelimi- 
nary qualitative examination, have shown that a large 
proportion of glucose is present, the urine must be di- 
luted with ten or twenty times its volume of water, and 
it is only when it contains but a very small quantity 
of sugar that the undiluted urine can be used for the 
analysis. 
10 c. c. of the urine are therefore diluted to 100 c. c. 
with distilled water, and another portion of 10 c.c. is 
diluted to 200 c.c. 124 
URINE. 
Exactly 10 c. c. of Fehling’s solution are measured 
into a small flask or capsule, and diluted with 30 or 40 
c. c. of Avater ; the liquid is heated by the aid of a lamp, 
and as soon as it begins to boil, the urine diluted to ten 
times its volume is alloAved to Aoav in from a burette. 
Towards the close of the experiment, the urine is added 
drop by drop, until the liquid above the precipitated cu- 
prous oxide has entirely lost its blue color; during the 
Avliole operation, the mixture must be kept boiling. The 
analysis is then terminated ; its accuracy may be tested 
by filtering a small part of the liquid from the precipitate, 
and dividing the filtrate into tAvo portions, one of which 
is tested by hydrogen sulphide, or by potassium ferro- 
cyanide, Avhile the other is boiled Avith a little more 
Fehling’s solution. If a precipitate be formed in either 
of the first two cases, the reduction is not complete, and 
more urine must be added ; if the drop of Fehling’s solu- 
tion added to the second portion be reduced, too much 
urine has been added, and the Avhole operation must be 
repeated. 
If only a few drops of the urine diluted to ten times 
its volume suffice to reduce the 10 c. c. of Fehling’s solu- 
tion, the experiment must be repeated Avith the urine 
diluted to tAventy Arolumes. 
Example.—If 11.5 c. c. of urine diluted to ten volumes 
be required to reduce 10 c. c. of Fehling’s solution, these 
11.5 c.c. must have contained 50 milligrammes of glu- 
cose ; hence 10 c.c. of the undiluted urine contain 
50 xlQQ==434:t7 milligrammes, or 1000 c.c. contain 43.47 
11.5 
grammes. The result, in grammes per 1000 c.c., is 
therefore obtained by dividing 5 X 100 by the number of 
cubic centimetres used, Avhen the urine is diluted to ten 
volumes, or by dividing 5 X 200 by the number of c. c. 
employed when the urine is diluted to 20 volumes. 
When urine contains both glucose and albumen, the 
latter must be removed before making an analysis for 
the glucose. The coagulation may be effected as di- 
rected in the preceding section. URINARY SEDIMENTS. 
125 
§ 158. The most convenient method for the estima- 
tion of ammonia in urine is that of Schlo sing and Neu- 
bauer. It depends upon the facts that all the ammonia 
present in organic matters is eliminated when they are 
mixed with milk of lime, and that all of the ammonia in 
a closed space is readily absorbed by sulphuric acid. 
The following solutions are needed :— 
1. A decinormal solution of sulphuric acid: 1 c.c.= 
.0049 gr. IPSO4. 
2. A decinormal solution of sodium hydrate: 1 c.c. = 
.0040 gr. NaOH. 1 c.c. of the former solution is exactly 
neutralized by 1 c.c. of the latter. (See'Appendix.) 
8. Solution of litmus. 
10 c.c. of the decinormal acid are placed in a small 
dish, over which is supported a capsule containing 20 
c.c. of the urine. The whole is placed on a piece of 
plate-glass, about 10 c.c. of milk of lime are added to 
the 10 c.c. of urine, and the vessels are immediately 
covered with a bell-jar of which the edges are well 
greased. The apparatus is allowed to stand for about 
forty-eight hours, after which the sulphuric acid is 
titrated with the decinormal sodium hydrate. Had no 
ammonia been disengaged from the urine and absorbed 
by the acid, exactly 10 c.c. of the sodium hydrate solu- 
tion would be required to neutralize the acid ; every 
cubic centimetre less than 10, corresponds to 0.0017 gr. 
of ammonia. 
This method is not quite accurate, the amount of 
ammonia found always being too great, for by the action 
of calcium hydrate a small quantity of urea is decom- 
posed, disengaging ammonia. 
AMMONIA. 
Urinary Sediments. 
§ 159. A few hours after emission, perfectly normal 
urine deposits a light cloud, composed of the ddbris of 
epithelial cells from the mucous membrane of the urinary 
tract, and no further change takes place until decom- 
position sets in. However, from various causes, a urine 126 
URINE. 
may be turbid when voided; or it may be clear when 
passed, and deposit an abundant sediment on cooling. 
Urine which is acid does not often yield any deposit 
until it is cold, the sediment in this case consisting of 
urates, free uric acid, mucus, calcium oxalate or phos- 
phate, and sometimes of hippuric acid or xanthine. On 
the contrary, alkaline urines are usually turbid when 
voided, and may hold in suspension pus, blood, large 
quantities of mucus, etc., and yield abundant sediments 
of earthy phosphates, ammonio-magnesium phosphate, 
and rarely earthy carbonates. 
The urine is allowed to stand in a conical glass until 
the sediment has completely subsided, and as much as 
possible of the clear liquid is removed by decantation. 
The separation of the sediment may sometimes be 
hastened by the addition of a few drops of acetic acid, 
but it must be remembered that the latter reagent will 
dissolve certain deposits. A drop of the liquid remain- 
ing with the sediment is transferred to a glass slide by 
the aid of a pipette, and, after being covered with a 
piece of thin glass, is subjected to microscopic exami- 
nation. 
The sediment maybe (1) crystallized, (2) amorphous, 
(3) organized, that is, containing cells, or (4) two or 
all of these forms may exist together. 
The following table, taken from Marais’Essai pratique 
des urines et des calculs urinaires, together with the 
illustrations referred to, will aid in the identification of 
the sediment. URINARY SEDIMENTS. 
127 
Microscopic form. 
Characteristic reactions. 
Substance. 
a.—Crystalline sediments. 
Very large crystals, generally isolated, transparent, and 
having sharply defined angles: typical form that’of a 
coffin-lid. 
Soluble in acetic acid ; not changed by potassium 
hydrate. 
Ammonio magnesium 
phosphate (Figs. 31 
Large crystals, generally grouped together, having a yel- 
low or brown color, often having a cracked appearance, 
and dark outlines. 
Insoluble in acetic acid : soluble in potassium liv- 
drate. 
and 32). 
Uric acid (Fig. 33). 
Small, transparent, isolated crystals, very refracting, 
sharp angles, octahedral form,'often resembling the re- 
versed side of an envelop. 
Insoluble in acetic acid and in potassium hydrate. 
Calcium oxalate (Figs. 34 
and 35). 
Hare crystalline sediments. 
Grayish sediment generally in alkaline urine. Colorless 
hexagonal plates or in six-sided prisms. 
Soluble in ammonia, from which they crystallize on 
evaporation; soluble also in sodium carbonate; 
precipitated from these solutions by acetic acid. 
Soluble in acids and alkalies. Its solution in nitric 
Cystine (Fig. 36). 
Ill-defined crystals, having the form of a whetstone (quite 
rare). '1 
Xanthine or hypoxan- 
acid becomes yellow when evaporated ; the re- 
sidue is colored orange-yellow by potassium hy- 
thine (see §§ 5"2aud 53). 
Four-sided rhombic prisms or needles, often mixed with 
crystals of uric acid and grouped with them. The urine 
is also very acid. 
drate, and assumes a violet-red tint when heated. 
Soluble in potassium hydrate; insoluble in acetic 
acid ; soluble in alcoholic ether. 
Hippuric acid (Fig. 37). 
Fine needles, grouped in tufts or stars. 
Soluble in potassium hvdrate and ammonia ; re- 
Tyrosine (Fig. 27). 
b.—Amorphous sediments. 
precipitated by acetic acid (see § 140). 
Hound or oval granules, having dark bodies ; isolated or 
united in groups of three or four or in chaplets; very 
small, difficultly perceptible granules, always united by 
irregularly marked surfaces. 
Soluble in acetic acid, without disengaging gas ; 
insoluble in potassium hydrate. 
Calcium phosphate. 
Hounded, isolated grains, concentrically striated or radi- 
ated (sometimes both) ; more or less dark and opaque 
Soluble in acetic acid, with evolution of gas. 
Calcium carbonate. 
Small yellowish granules, sometimes very small and in 
series ; sometimes larger, having dark bodies and yellow 
Slowly soluble in acetic acid, colorless, rectangular 
tables at the same time appearing. 
Urates (Fig. 38). 
centies; united in masses, or isolated and covered with 
spike-like points. 
Very small, isolated granules, having a vortex-like motion 
(Brownian movement). 
Molecular granules (Fig. 
Insoluble in acetic acid and in potassium hydrate. 
Rounded, highly refracting granules of various size. 
Insoluble in acetic acid; soluble in a mixture of 
39*. 
Fat globules (Fig. 40). 
alcohol and ether, especially after the addition of 
L 
a drop of sodium hydrate. 
Unorganized Sediments. 128 
URINE. 
Fig. 31. 
Fig. 33. 
Stellate crystals of triple phosphate. 
Fig. 32. 
Ammonio magnesium phosphate and crystals 
of sodium urate grouped in stars. 
Uric acid. 
Fig. 34. 
Fig. 35. 
Calcium oxalate. 
Calcium oxalate. URINARY SEDIMENTS. 
129 
Fig. 36. 
Fig. 37. 
Cystine. 
Fig. 39. 
Molecular granules. 
Hippuric acid. 
Fig. 38. 
Fig. 40. 
Fat cells. 
Ammonium urate. URINE. 
Microscopic characters. 
Characteristic reactions. 
Substance. 
a.—Cellular form, more or less rounded. 
Globules, always round, having regular or serrated bor- 
ders, without nucleus, generally having a central depres- 
sion, isolated, united in piles, or imprisoned in filaments 
of fibrin or mucus. 
Round or oval globules, contours not well marked, contents 
white, grayish, granular, or nuclear; isolated, or united 
in masses, in the latter case polygonal, often imprisoned 
in mucus and elongated. 
Very small, highly refracting, round, or oval globules ; 
sometimes having one or two brilliant nuclei, or wart- 
like protuberances; isolated or united in chaplets. (Re- 
quire a magnifying power of 500 diameters.) 
Small, refracting, oval, hyaline corpuscles, having a long, 
delicate, filament-like tail. 
Swelled up by acetic acid, or shrivelled like rasp- 
berries ; not colored by carmine ; disappear in 
potassium hydrate. 
Rendered paler by acetic acid, which causes the 
appearance of two or three nuclei; stained by car- 
mine ; soluble in potassium hydrate. 
Not modified by acetic acid, or colored by carmine ; 
the interior nuclei are colored yellow by iodine 
water. , 
Unchanged by reagents. 
Red blood globules 
(Figs. 41 and 42). 
Leucocytes (Fig. 43). 
Spores or organized fer- 
ments. 
Spermatozoids (Fig. 44). 
b.—Cylindrical or fusiform filaments. 
Rounded, cylindrical, fusiform, or polygonal bodies, having 
granular contents and more often presenting several 
nuclei. 
Large cylinders, having variable appearances ; may be 
long or short; sometimes twisted, or in a wave-like form. 
(Require 120 diameters.) 
Cylinders like very small short rods, generally numerous, 
and all similar ; transparent, often agitated with an un- 
dulatory movement. (Require 400 or 500 diameters.) 
Rendered paler by acetic acid, which makes the 
nuclei more prominent; colored, especially the 
nuclei, by carmine. 
Rendered pale by acetic acid ; again developed by 
alkalies. 
Not modified by acetic acid, which, however, re- 
tards or arrests their movements. 
Epithelial cells (Fig. 45). 
Tube casts from the kid- 
neys (Fig. 46). 
Vibrios. 
c.—Filaments or flakes of various appearances. 
r 
Very thin filaments, differing more or less from each 
other, and interlaced. 
Not changed by acetic acid. 
Paled by acetic acid, the fibres di-appear and give 
place to a swollen, amorphous, transparent mass, 
which again becomes fibrous when treated with 
potassium hydrate. 
Reudered more prominent by acetic acid, which at 
the same time produces a dotted or striated ap- 
pearance. 
Algse and fungi. 
Clots of fibrin. 
Mucus. 
Organized Sediments. URINARY SEDIMENTS. 
131 
Fig. 41. 
Fig. 42. 
Natural blood corpuscles. 
Collapsed blood corpuscles. 
Fig. 44. 
Fig. 43. 
White blood corpuscles. 
Spermatozoids. 
Fig. 45. 
Fig. 46. 
Epithelial and mucus. 
Casts of the uriniferous tubules. URINE. 
Fig. 47. 
a. Cotton fibres ; 6, flax fibres ; c, hairs ; d, air-bubbles; e, oil-globulesg, h, 
starch granules ; i, vegetable structures ; k, muscular fibres. 
As more or less extraneous matters, derived either 
from atmospheric dust or the vessels in which the urine 
has been collected, may be expected to be present with 
the sediment, care must be taken not to confound such 
matters with the deposit proper. The principal foreign 
bodies which are likely to be met with are represented in 
figure 47, taken from Roberts’ Urinary Diseases. URINARY SEDIMENTS. 
The more common deposits are ammonio-magnesium 
phosphate, calcium phosphates, calcium oxalate, and 
urates; the latter constitute the red or brown sediments, 
known as brick-dust deposits, so frequently seen in febrile 
Fig. 48. 
Saccharomyces mjcoderma (yeast plant). 
urine ; their color is due to the pigment of the urine, and 
depends altogether on the proportion of coloring matter 
present,—in pale urines they are almost or quite color- 
less. Ammonium urate is much the more characteristic 
under the microscope, the spike-like projections being 
generally well marked. Sodium urate, which seems to 
constitute the bulk of the red deposits, is in smaller 
granules having no projections. The two may be dis- 
tinguished by allowing a drop of hydrochloric acid to 
penetrate under the thin cover of the microscope slide. 
Uric acid separates, and at the same time sodium chlo- 
ride or ammonium chloride crystallizes out; the former 
crystallizes in cubes, the latter in leaf-like or branched 
forms. 
Calcium oxalate is sufficiently characterized by its 
crystalline form, and, like the urates, is insoluble in 
ammonia. The latter property serves for the distinction 
of urates and calcium oxalate and phosphate from tyro- 
sine, cystine, and xanthine, which are soluble in ammonia. 
Uric acid may easily be recognized by the murexide 
test; tyrosine and xanthine by their behavior when 
treated with nitric acid and potassium hydrate ; cystine 
by the black stain which it produces when placed upon 
a silver surface and moistened with potassium hydrate. 
Sometimes urine is turbid and even milky from the 
presence of finely divided fat globules ; in this case it is 
rendered clear and transparent by agitation with ether, 134 
URINE. 
and, when the latter liquid is decanted and evaporated, 
it leaves the fat in a solid or semi-solid state. 
If the urine which is voided by women during preg- 
nancy be allowed to stand for a day or two, a whitish 
pellicle gradually forms on its surface. This pellicle has 
a fatty appearance, and was formerly called kiestine. It 
contains, however, no peculiar principle, but is shown, 
by a microscopic examination, to consist of ammonio- 
magnesium phosphate, some fat globules, a few vibrios, 
and the results of the destruction of epithelial mucus. 
Sometimes the microscopic examination of urine re- 
veals the presence of the yeast plant (saccharomyces 
my coderma). In such a case the urine should always be 
tested for glucose. The saccharomyces my coderma is 
represented in fig. 48. It may appear in detached cells, 
or as a number of buds, clustered together in a sort of 
chaplet. 
The consideration of the organized sediments of urine 
belongs properly to pathological microscopy. 
Urinary Calculi. 
§ 160. The calculi which arc sometimes found in the 
bladder, and indeed throughout the whole urinary tract, 
differ greatly in their physical appearances arid their 
chemical composition, but always consist of normal or 
abnormal constituents of the urine. They are as varied 
as the unorganized urinary sediments which have already 
been described, and they may be considered as agglome- 
rated sediments. They may be small, like grains of 
sand; they then constitute gravel, and are passed with 
the urine, producing little or no pain. They may*, how- 
ever, attain great magnitude, and necessitate a surgical 
operation for their removal. They generally contain a 
nucleus, around which the calculus is built up in layers, 
sometimes of the same, sometimes of a different chemical 
nature. The nucleus may be a crystal of uric acid which 
has separated spontaneously in the kidney or bladder; 
it may be a clot of blood, or a tube-cast from the kidney; 
sometimes, but rarely, it is formed by a foreign body 
which has been accidentally introduced into the bladder. URINARY CALCULT. 
135 
A chemical examination of gravel or small calculi 
which have been passed with the urine, is indispensable, 
as it may modify the treatment to be adopted, and, in 
case large calculi exist in the bladder, it may influence 
the nature of the operation to be performed, and enable 
the surgeon to decide between lithotrity and lithotomy. 
The nature of sand-like calculi may generally be de- 
termined by the table of urinary sediments, page 127, and 
the same chemical tests are applicable to this gravel as 
those which serve for the identification of larger calculi. 
The stone should first be cut through the middle by 
means of a fine saw; it then immediately becomes appa- 
rent whether the calculus is 
uniform throughout, or whe- 
ther, as is usually the case, it 
is made up of different sub- 
stances in concentric layers 
(Fig. 49). If the stone be 
desired for a collection, its 
nature may be determined, 
and sufficient material ob- 
tained for analysis, by boring 
a hole in one side. 
The following mode of ope- 
ration permits, at the same time, the detection of the 
constituents of the calculus, and a partial quantitative 
analysis. If the latter is dispensed with, the weighings 
are omitted:— 
a) Estimation of water.—The stone should be washed 
with cold water, before crushing, in order to remove the 
adhering urinary matter: a quantity of the finely pul- 
verized matter is then weighed, dried at 100° in an air- 
oven, and again weighed. The loss of weight indicates 
the quantity of water present. A small quantity of 
ammonia will be volatilized in this operation, if that com- 
pound form any considerable proportion of the calculus. 
Calculi consisting principally of phosphates may contain 
a large proportion of w'ater, losing even half their weight 
by desiccation; of course, if the calculus has been allowed 
to dry for any time in the air before the analysis is made, 
it will hardly be useful to estimate the water. 
Fig. 49. 
Mixed calculus. 136 
URINE. 
(>) A small weighed portion of the powder is intro- 
duced into a porcelain or platinum crucible, moistened 
with a drop or two of water, and a few drops of acetic 
acid are added. Any effervescence denotes the presence 
of a carbonate. 
e) A little strong nitric acid is then added, and the 
mixture is carefully evaporated to dryness, spreading it 
out as much as possible on the sides of the crucible. If 
uric acid be present, the mass acquires a reddish color, 
which changes to purple on the addition of a drop of very 
dilute ammonia. 
d) The residue is now heated to bright redness, until 
the whole of the carbonaceous matter is entirely de- 
stroyed ; if no residue remain, the calculus contains no 
mineral matter; if a residue be left, its weight is that of 
the inorganic constituents. 
e) If no mineral matter be present, the stone consists 
of one or more of the following substances: — 
Uric acid 
Ammonia urate 
Xanthine 
Cystine. 
Organized bodies, such as epithelial mattter, 
pigment, or fibrinous substances. 
/) The presence of uric acid or ammonium urate is 
detected by the murexide test (§ 50); the discrimination 
between the two is made by heating a portion of the 
powder with a solution of potassium or sodium hydrate. 
If ammonium urate be present, ammonia will then be 
disengaged. If, however, in addition to uric acid, the 
stone contain ammonio-magnesium phosphate, ammonia 
will be disengaged by the action of an alkaline hydrate, 
even though no ammonium urate 
be present; in this case it can- 
not easily be decided whether 
the uric acid be free, or Avhether 
it exist in combination with am- 
monia. 
Uric acid is the most common 
constituent of vesical calculi. 
g) Should the murexide test 
have failed to indicate the pre- 
sence of uric acid, but the residue of the evaporation of 
Fig. 50. 
Uric acid calculus. URINARY CALCULI. 
the nitric acid be yellow, xanthine may be present. In 
this case the residue will assume an orange color when 
treated with potassium hydrate, and will then become 
reddish-violet when heated. (Compare § 52.) Xanthic 
calculi are of rare occurrence. 
h) A stone which is entirely combustible, and contains 
neither uric acid nor xanthine, may consist of cystine. 
It will then dissolve in ammonia, and by slow evapora- 
tion of the ammoniacal solution the cystine will be de- 
posited in characteristic hexagonal tables, the nature of 
which can be ascertained by the tests given in section 74. 
i) Calculi consisting of albuminoid and epithelial mat- 
ters are very rare ; they disengage an odor of burnt 
horn when heated, and are soluble in potassium hydrate, 
the solution responding to the usual tests for albuminoid 
substances. 
k) A stone which is partly combustible and which 
responds to the murexide test, may contain the urates of 
potassium, sodium, magnesium and calcium, and possibly 
calcium oxalate, magnesium or calcium phosphate, am- 
monio-magnesium phosphate, magnesium or calcium car- 
bonate. 
If the presence of an alkaline urate be suspected, the 
residue of the incineration is exhausted with a little 
water, and the solution, which would contain the potas- 
sium or sodium as carbonate, will have an alkaline re- 
action ; it is tested for potassium by platinic chloride, 
and for sodium by the flame test. 
If the residue of the combustion contain neither potas- 
sium nor sodium, it is treated with a little dilute acetic 
acid, and the solution is neutralized by ammonia, and 
tested for calcium by ammonium oxalate, and for magne- 
sium by ammoniacal sodium phosphate containing some 
ammonium chloride. If the presence of either calcium 
or magnesium be found by these tests, and the original 
matter effervesce when treated with acetic acid, it cannot 
be decided whether these metals originally existed as 
urates or as carbonates; but if no effervescence take 
place when the original calculus is treated with acetic 
acid, it may be concluded that an earthy urate is pre- 
sent. 138 
URINE. 
1) To detect calcium oxalate, a portion of the calculus 
is treated with dilute hydrochloric acid, the solution is 
filtered, and neutralized with ammonia. The calcium 
oxalate, which is soluble in hydrochloric acid, is then 
thrown down unchanged. It is insoluble in acetic acid. 
When heated, it is converted into calcium carbonate, 
which dissolves with effervescence in acetic acid; if the 
heat be raised to redness, the calcium carbonate is re- 
duced to lime, and the latter will 
restore the blue color to moistened 
red litmus paper. 
Stones consisting of calcium 
oxalate are hard, and covered with 
rough projections, from which 
they have received the name of 
mulberry calculi. 
rn) If the residue of the com- 
bustion of the calculus do not 
effervesce when treated with acetic acid, it consists of 
one of the phosphates. 
Calculi consisting of calcium phosphate are usually 
smooth and have a polished appearance; they are com- 
posed of layers which readily 
separate from each other when 
the stone is broken. They are 
almost infusible. 
Calcium phosphate dissolves 
without effervescence in dilute 
nitric acid, and is reprecipitated 
when the solution is neutralized 
by ammonia. If the precipitate 
be dissolved in acetic acid, the presence of calcium may 
be detected by the addition of ammonium oxalate to the 
solution. 
Stones containing ammonio-magnesium phosphate leave 
on ignition a residue which is fusible, and solidifies to a 
white, enamel-like mass on cooling. Such calculi dis- 
engage ammonia when heated with potassium hydrate. 
Ammonio-magnesium phosphate dissolves in dilute 
hydrochloric acid, and is again precipitated by the 
Fig. 51. 
Calcium oxalate calculus. 
Fig. 52. 
Calcium phosphate calculus. URINARY CALCULI. 
addition of ammonia. The precipitate so formed is 
crystalline, and may be recognized under the microscope. 
Calculi frequently consist of ammonio-magnesium 
phosphate mixed with calcium phosphate; they are soft, 
and may he readily crushed. When heated with potas- 
sium hydrate, they disengage ammonia. They dissolve 
in dilute hydrochloric acid, and on the addition of 
ammonium oxalate, calcium oxalate is precipitated, while 
magnesium may be detected in the filtered liquid by 
neutralizing the latter with ammonia; ammonio-magne- 
sium phosphate is then thrown down as a crystalline 
precipitate. 
Phosphoric acid may be detected in all phosphatic 
calculi, by dissolving them in nitric acid, and adding 
ammonium molybdate to the solution. Phospho-molyb- 
date of ammonium separates as a yellow precipitate, 
whose formation is favored by heating the liquid. 
n) A calculus which contains calcium or magnesium 
carbonate, effervesces when treated with acetic acid, and 
the earthy metal may he detected in the solution ob- 
tained. Such calculi are rare in man. 
o) Sometimes a calculus contains several of the mineral 
compounds which have been mentioned, and uric acid or 
urates in addition. By boiling such a stone (pulverized) 
with a large quantity of water, most of the uric acid and 
urates may be removed; from the residue, acetic acid 
will dissolve the carbonates and phosphates, and the 
latter are precipitated by the addition of ammonia to the 
solution. Acetic acid leaves calcium oxalate undissolved; 
this is, however, soluble in dilute hydrochloric acid, and 
may be precipitated in its characteristic crystalline form 
by very slowly neutralizing the solution with ammonia. 140 
BLOOD. 
BLOOD. 
§ 161. The general physical properties of blood are 
well known; it is a somewhat thick, viscous liquid, having 
a red color, which is bright scarlet in the arteries and 
much darker in the veins. It has a faint odor, and a 
salty, unpleasant taste. The specific gravity of human 
blood is usually comprised between 1050 and 1058; it 
may, however, vary from 1045 to 1075 (Gorup-Besanez). 
It is always alkaline. 
Anatomically, the blood is composed of a serous 
liquid, called the plasma, in which are suspended— 
Red corpuscles, the characteristic blood-cells ; 
White globules, or leucocytes; 
Small granular masses. 
The history of the blood includes a consideration of its 
anatomical constituents, and of the chemical principles 
contained in each of the constituents, as well as of the 
chemical nature of the blood as a mass. 
§ 162. Normal chemical constituents.—Normal blood 
contains water, fibrin (fibrinogen and fibrino-plasmin), 
albumen, hemoglobin, lecithine, cholesterin, and small 
quantities of urea, glucose, creatine and creatinine, fatty 
matters and alkaline salts of the fatty acids, and perhaps 
traces of uric acid. The mineral matters present are 
alkaline chlorides, carbonates, sulphates and neutral 
phosphates, calcium and magnesium phosphates, iron and 
traces of silica. 
Besides these bodies, blood holds in solution oxygen, 
nitrogen, and carbon dioxide. 
The hemoglobin, lecithine and iron, exist only in the 
red corpuscles; the other constituents are partly common 
to these corpuscles and to the plasma, and in part peculiar 
to the latter; in the first case are water and the inorganic 
salts; in the second are fibrin, albumen, fatty matters 
and salts of fatty acids, cholesterin, urea, glucose, 
creatine, creatinine, and uric acid. 
§ 163. Abnormal constituents.—The principal abnor- 
mal substances proper which have occasionally been de- GENERAL CHEMICAL PROPERTIES. 
tected in blood, are volatile fatty acids (from formic to 
butyric), biliary acids and pigments, hypoxanthine, gela- 
tin, lactic acid, leucine and tyrosine, and ammonium 
carbonate. 
All of the substances which may be accidentally or 
medicinally introduced into the system, and which pass 
into the blood without immediate change, may also be 
detected in the blood ; among these substances are the 
metallic poisons, alkaloids, hydrocyanic acid, carbon 
monoxide, etc. 
General Chemical Properties. 
§ 164. Shortly after blood is drawn from the vessels, 
it coagulates, forming a solid mass ; it also coagulates 
in the vessels, if from any cause its circulation he ar- 
rested. The coagulation of drawn blood is hastened bj 
agitation, and is retarded or even completely arrested 
by the presence of an alkaline hydrate or carbonate, or 
of traces of mineral or organic acids, or by certain salts, 
among which may he particularly mentioned sodium sul- 
phate, potassium nitrate, and common salt. 
If coagulated blood he allowed to stand, the clot gradu- 
ally contracts in volume during a day or more, and at 
the same time a viscid liquid called the serum is pressed 
out of the contracting mass. 
When freshly drawn blood is allowed to stand, without 
any agitation, the suspended globules have a tendency 
to sink to the bottom of the containing vessel, their spe- 
cific gravity being greater than that of the serum. The 
upper layer of the mass then becomes almost colorless 
by the time that the blood solidifies, and this slightly 
concave, almost transparent, firm and elastic upper layer 
imprisons the greater part of the Avhite corpuscles. It 
has been called the buffy-coat. The lower portions of 
the clot are softer, less elastic, and contain the greater 
mass of the red corpuscles. The larger the proportion 
of fibrin in the blood, the more voluminous is the buffy- 
coat, but the same effect is observed when the blood is 
deficient in red corpuscles ; in the latter case, however, 
the clot is usually quite small, and floats on the serum 
when the latter separates. When the blood is very rich BLOOD. 
in red corpuscles, the buffy-coat is not well marked, and 
the clot is abundant. 
If, instead of being allowed to stand, freshly drawn 
blood be agitated by the aid of a glass rod, or a bundle 
of twigs, the fibrin coagulates on the rod or the twigs, 
in colorless, elastic filaments. 
By mixing blood, thus freed from its fibrin, with five 
or six times its volume of a cold saturated solution of 
sodium sulphate, a liquid is obtained from which the red 
corpuscles may be separated by simple filtration, the 
liquid which passes through the filter being nearly color- 
less. This liquid coagulates in a mass when heated, by 
reason of the albumen which it contains. Freshly drawn 
blood also coagulates into a sort of paste when mixed 
with alcohol, mineral acids, or other agents which coagu- 
late albumen. 
Carbon monoxide expels the oxygen from the hemo- 
globin of blood, coloring the latter violet-red; oxygen 
will not readily expel the carbon monoxide which is 
thus absorbed. This fact explains the poisonous action 
of carbon monoxide. 
If dried blood be mixed with a little sodium chloride, 
and then heated to boiling with glacial acetic acid, a 
brownish-red liquid is obtained, which soon becomes al- 
most black, and deposits crystals of hemin as a dark, 
brilliant powder. 
The serum of blood, as it separates from the clot, has 
a color varying from yellow to reddish ; it is generally 
alkaline, and coagulates on being heated. It is precipi- 
tated by alcohol, mineral acids, and many metallic salts. 
When serum is neutralized by the addition of a few drops 
of acetic acid, and then poured into boiling water, the 
albumen coagulates in large flakes which may be easily 
separated by filtration. 
The residue obtained after thoroughly incinerating 
dried blood, consists of potassium and sodium chlorides, 
potassium, sodium, calcium, and magnesium phosphates, 
iron, traces of other metals, and a little silica; there 
are also present alkaline carbonates, produced by the 
combustion of alkaline salts of organic acids. These 
salts are contained almost wholly in the clot; the serum ANALYSIS OF BLOOD. 
143 
contains only a very small proportion, its ash consisting 
principally of the alkaline base which exists in combina- 
tion with the albumen. 
Analysis of Blood. 
§ 1G5. The chemical examination of blood may be 
undertaken either for the detection of certain normal or 
abnormal constituents, or for purposes of reseacli, or 
for the estimation of the proportions of one or more of 
the elements present. 
Those substances which are contained in the blood in 
tolerably large proportions, may be detected by methods 
which have already been indicated when treating of the 
general properties of such compounds. For some bodies, 
however, which are usually present in very minute quan- 
tities, special precautions must be observed. These bodies 
are best detected in the serum, and to obtain the latter, as 
large a quantity of the blood as possible should be allowed 
to coagulate, and the clear liquid is separated from the 
clot by decantation. 
§ 166. Urea.—For the detection of urea, the clear 
serum is mixed with three or four times its volume of 
strong alcohol, and allowed to stand several hours, after 
which it is filtered, and the filtrate evaporated nearly to 
dryness on a water-bath. The residue is then exhausted 
with absolute alcohol, and the extract so obtained is filtered 
and again evaporated nearly to dryness. The residue 
is dissolved in a small quantity of water, and the solu- 
tion filtered; the filtrate is freed from phosphates by 
the addition of baryta-water, and the excess of barium 
hydrate is precipitated by a current of carbon dioxide. 
The clear liquid obtained by filtration is concentrated to 
a syrupy consistence, and the vessel containing it is then 
placed in ice-water, or in a very cold place, and a few 
drops of concentrated nitric acid are added. After 
standing some time, the solution deposits crystals of 
urea nitrate, which may be identified by the properties 
described in section 41. 
§ 167. Uric acid.—As large a quantity as possible 
of the serum is freed from albumen by boiling it with two 144 
BLOOD. 
or three times its volume of water to which a few drops 
of acetic acid have been added. The mixture is filtered 
through a cloth, and the filtrate is evaporated to dryness 
on a Avater-bath. The residue is exhausted several times 
with boiling water, the united extracts are filtered while 
boiling, and the filtrate is evaporated to a small bulk, 
mixed with a little strong acetic acid, and allowed to 
stand several days. The crystals which separate are 
then examined microscopically, and submitted to the 
chemical tests indicated in section 50. 
Uric acid may also be separated from serum of blood 
by the method described in section 51. 
§ 168. Creatine and creatinine.—The albuminous 
matters are removed from the serum by boiling with 
water and a few drops of nitric acid ; the filtrate is pre- 
cipitated by basic lead acetate, the liquid again filtered, 
and the filtrate freed from excess of lead by hydrogen 
sulphide. The clear filtered solution is evaporated to a 
small bulk on a water-bath, the residue is exhausted with 
absolute alcohol, and the alcoholic solution mixed with a 
neutral solution of zinc chloride, and the operation con- 
tinued as in section 59. 
§ 169. Glucose.—The serum, or defibrinated blood, 
is mixed with four times its volume of alcohol, and after 
standing a few hours the mixture is filtered. A few 
drops of acetic acid are added to the filtrate, which is 
then heated to boiling, and again filtered ; the new fil- 
trate is evaporated to dryness on a water-bath. The 
residue is exhausted with a little warm water, and the 
solution is tested for glucose according to the methods 
indicated in sections 21-24, preferably by means of 
Fehling’s solution. 
§ 170. Mineral salts must be sought in the ash ob- 
tained by evaporating to dryness and carbonizing about 
50 c.c. or more of the blood. The carbonaceous mass 
is exhausted with warm water, the liquid filtered, and 
evaporated to dryness ; the residue consists of the solu- 
ble mineral salts, and these are detected by the usual 
chemical tests. Silver nitrate added to the solution pro- 
duces a white precipitate, indicating the presence of 
chlorides; barium chloride precipitates the sulphates ; ANALYSIS OF BLOOD. 
145 
ammonia, ammonium chloride, and magnesium sulphate, 
together, precipitate the phosphoric acid. The carbona- 
ceous residue from which the soluble salts have been 
extracted, still contains the insoluble salts. It may be 
incinerated, and the salts remain as a brownish ash, 
which will dissolve in boiling hydrochloric acid ; iron 
may be easily detected in this solution. 
§ 171. Biliaby acids and pigments, if present, may 
be detected by Pettenkofer’s and Gmelin’s tests, which 
have already been described (§§ 135 and 136). 
§ 172. Leucine and tyrosine.—These bodies appear 
to be present in blood only in acute diseases of the liver; 
for their detection, the serum or defibrinated blood is 
poured into boiling water, which precipitates .the albu- 
men, and the filtered liquid and wash-water are evaporated 
to about one-third the volume of the blood taken. Basic 
lead acetate is then added, and the subsequent steps of 
the operation are conducted according to the indications 
given in section 140. 
§ 173. Ammonia.—The following method, proposed 
by Briicke, depends upon the use of Nessler’s reagent; 
the latter is made by dissolving 2 grammes of potassium 
iodide in 5 c.c. of distilled water, warming the liquid, 
and adding mercuric iodide as long as it continues to be 
dissolved. After cooling, the solution is diluted with 
20 c.c. of water, allowed to stand several hours, filtered, 
and 20 c.c. of the filtrate are mixed with 30 c.c. of a 
concentrated solution of potassium hydrate, as free as 
possible from potassium carbonate. If the liquid become 
turbid, it must again be filtered, and no ammonia should 
be present in the atmosphere of the room in which it is 
prepared. 
Some of the blood to be examined is then introduced 
into a small flat dish which may be hermetically closed 
by a glass plate. A very small porcelain capsule is 
fastened to the inside of the glass cover by the aid of a 
little wax, and a few drops of very dilute sulphuric acid 
are spread out over its surface. The cover is then oiled 
on the edges, and placed over the vessel containing the 
blood, and the whole is allowed to stand for an hour or 
longer in a tolerably warm place. The cover is then 146 
BLOOD. 
removed, and a drop or two of Nessler’s reagent is 
poured into the capsule which had been moistened with 
sulphuric acid. If ammonia has been disengaged, it will 
have been absorbed by the sulphuric acid, and a reddish- 
brown color is produced on the addition of Nessler’s re- 
agent. 
§ 174. Carbon monoxide may be detected in the 
blood after poisoning by that gas. The spectroscopic 
characters of oxyhemoglobin and of hemoglobin contain- 
ing carbon monoxide, have already been indicated (§ 87). 
The blood to be examined is properly diluted with water, 
in order that it may not be too opaque, and is placed in 
a small glass trough having parallel plane glass sides, 
about one centimetre apart. The rays of light from a 
gas jet or oil lamp are caused to traverse this solution 
perpendicularly before entering the narrow slit of the 
spectroscope. The absorption bands then produced by 
blood containing carbon monoxide much resemble those 
produced by oxyhemoglobin, but the band immediately 
to the right of the D line is somewhat nearer E (see fig. 
23). When, in such a case, the blood is treated with 
reducing agents, such as ammonium sulphide, the absorp- 
tion bands do not disappear, nor does the absorption band 
of reduced hemoglobin become visible. If no carbon 
monoxide be present, and the blood be treated and exam- 
ined as directed, the absorption bands of oxyhemoglobin 
rapidly disappear, being replaced by the wide and less 
marked band characteristic of reduced hemoglobin. 
Quantitative Analysis. 
§ 175. The blood being a mixed liquid, the quantita- 
tive estimation of its constituents may be directed spe- 
cially to the globules, which together with the fibrin form 
the clot, or to the plasma, which represents normal blood 
without its corpuscles, or to the serum, which contains 
neither globules nor fibrin, and very little mineral salts. 
The following table, by Becquerel and Rodier, is in- 
tended to represent the average composition of human 
blood QUANTITATIVE ANALYSIS. 
147 
Density ........ 1060 
Water 781.60 
Globules 135.00 
Albumen . 70.00 
Fibrin ........ 2.50 
Fatty, extractive, and saline matters . . 10.00 
Phosphates ....... 0.35 
Iron ........ 0.55 
1000.00 
It must be remembered, however, that the exact esti- 
mation of all of the constituents of blood, that is, of the 
proximate principles, globules, salts, fatty matters, etc., 
is almost impossible, and complete analyses can, there- 
fore, only be regarded as giving approximate results. 
We will first consider a general plan by which a toler- 
ably accurate idea of the constitution of the blood may he 
obtained, and will then take up specially some of the 
constituents more difficult to estimate. 
The blood is divided into three portions immediately 
after it is drawn. 
20 grammes are reserved for the estimation of water, 
solid matters, and mineral salts. 
At least 40 grammes are beaten up with any suitable 
appliance for the separation and estimation of fibrin. 
40 grammes are allowed to coagulate in a rather flat, 
covered vessel; the serum is then decanted into a 
platinum capsule, and dried at 100°. The weight of the 
residue is that of the albumen plus certain mineral salts, 
and extractive and fatty matters. The latter are esti- 
mated separately, and their weight being deducted from 
that of the impure albumen, the proportion of pure albu- 
men is obtained. The total proportion of Avater in the 
blood having already been determined, as indicated 
farther on, the amount of albumen corresponding to the 
Avater so estimated is calculated, supposing all of the 
water to enter into the composition of the serum, and the 
fibrin, globules, and salts to be perfectly dry. 
In the same manner the Aveight of the dry globules is 
estimated indirectly ; the total Aveight of the organic 
matter in 1000 parts of serum being knoAvn, together 
with that of the fibrin and salts in 1000 parts of blood, and 148 
BLOOD. 
the total weight of the solid matter in 1000 parts of blood 
being known, the difference will represent the dry globules. 
While, as has been said, this method can only be 
approximate, it may be useful, in certain cases, to indi- 
cate which part of the blood is deficient or in excess. 
An example will elucidate the method of calculation. 
The estimation of water and of fixed matters has shown 
1000 grammes of blood to contain— 
Water ...... 788.50 grammes. 
Solid matter 
organic 
mineral 
202.34 
9.16 
211.50 “ 
The determination of fibrin has demonstrated the pres- 
ence of 2.852 grammes of that substance in 1000 of blood. 
The serum of the third portion of blood lias been found 
to consist of, 
Solid matter 
Water ...... 917.28 grammes^ 
i organic . 75.63] 
{mineral . 7.09; 
82.72 
The serum corresponding to 788.50 grammes of 
water, or 1000 grammes of blood, would then contain 
82.72x788.5 ,. n 
——gj-ij-Qg or 71.11 grammes ot impure albumen, 
which would be composed of 
Albumen and extractive matters 65.01 
Mineral salts . . ... 6.11 
71.11 grammes. 
The sum of the weights of the fibrin and salts con- 
tained in 1000 grammes of blood, and of the organic 
matter in the serum of 1000 parts of blood, is 
2.352+ 65.01+ 9.16. . . = 76.522 grammes. 
The solid matter in 1000 grammes 
of blood = 211.500 “ 
Hence the dry globules would weigh 134.978 “ 
The analysis has thus shown 1000 grammes of blood 
to contain 
Water ...... 788.500 grammes. 
Fibrin 2.352 “ 
Albumen and extractive matters . 65.010 “■ 
Corpuscles ..... 134.978 “ 
Mineral salts ..... 9.160 “ ESTIMATION OF MINERAL SALTS. 
149 
§ 176. Estimation of water and of solid matters. 
—In order to obtain accurate results in the estimation 
of water, the blood must not be allowed to undergo any 
evaporation between the time at which it is drawn and 
the moment of weighing. It is, therefore, necessary to 
receive the blood directly in a small bottle, which can be 
corked immediately, when a sufficient quantity has been 
obtained. The bottle and its contents are then weighed 
and the previously determined Aveight of the bottle is 
deducted. The bottle is then well shaken, in order to 
break up the fibrin, and the blood is poured out into the 
platinum capsule in which it is to be dried. The bottle 
is Avashed out with a little diluted Avater, which is added 
to the contents of the capsule. The latter is then dried 
in an air oven at 100°, until its Aveight becomes sensibly 
constant. The dry residue is quite hygroscopic, and the 
capsule should, therefore, be covered during the Aveigh- 
ings. The desiccation is not perfect at 100°, but if the 
temperature be raised much higher, some of the constitu- 
ents of the blood may undergo partial decomposition. 
Hence if a more thorough desiccation be desired, it is 
safer to effect it by continuing the drying over sulphuric 
acid in a vacuum. 
The residue in the capsule represents the total solid 
matter in the quantity of blood desiccated : the difference 
between the Aveight of the latter quantity, and that of 
the residue, is the Aveight of the Avater. 
§ 177. Estimation of the mineral salts.—The total 
proportion of mineral salts present, cannot be accurately 
determined in one operation, for a considerable propor- 
tion of the chlorides might be volatilized by the high 
temperature necessary for the destruction of the last 
traces of carbon. The soluble salts and insoluble salts, 
are therefore estimated separately, and for this purpose 
the residue obtained after estimating the water and fixed 
matters is cautiously heated over a lamp until it is thor- 
oughly carbonized, and the carbon begins to burn. The 
black mass is then completely exhausted with Avarm Avater, 
and the solution so obtained is evaporated to dryness in a 
platinum capsule ; the Avhite residue is heated to dull red- 
ness, and after cooling is weighed, its Aveight being that of 150 
BLOOD. 
the soluble salts. The carbonaceous mass which has been 
exhausted with water is dried, and if it has been col- 
lected on a filter, is returned to the capsule, together 
with the filter; the whole is completely incinerated, and 
the weight of the filter-ash is deducted from that of the 
brownish-residue. The weight of the insoluble salts so 
found is added to that of the soluble salts previously de- 
termined. 
§ 178. Estimation of fibrin.—The blood should be 
collected and beaten in a small precipitating glass or 
beaker, to the top of which is ad- 
apted a caoutchouc cover, through 
Avhich passes the handle of a whale- 
hone agitator. (Eig. 58.) When 
the cover is in position, the lower 
part of the agitator, which is some- 
what expanded, should almost touch 
the bottom of the vessel. The total 
weight of this apparatus, empty and 
quite dry, is determined before the 
analysis. (Hoppe-Seyler.) 
30 or 40 grammes of the blood 
to be analyzed are collected in the 
vessel, directly from the vein ; the 
cover is immediately replaced, and 
the blood is agitated for ten or fif- 
teen minutes. The whole is then 
allowed to cool, and the weight of 
the blood taken is determined by deducting the weight of 
the empty apparatus from the total weight of apparatus 
and blood. No loss takes place during the cooling, as 
the caoutchouc cover prevents sensible evaporation. 
The cover is then removed, the vessel nearly filled by 
pouring in distilled water, and the whole is well agitated. 
The fibrin deposits in flakes; the transparent superna- 
tant liquid is decanted into another vessel, and the fibrin 
is shaken up with a fresh quantity of water, containing a 
trace of common salt. The mixture is then poured upon 
a small filter which has been dried at 110° and weighed. 
By the aid of a clean pair of forceps, any filaments of 
fibrin adhering to the whalebone beater are removed and 
Fig 53. ESTIMATION OF FIBRIN. 
151 
added to that on the filter. The mass is then thoroughly 
washed with pure water,—most efficiently by the aid of 
a filter-pump,—until the wash-water passes through 
colorless, and nearly all the color of the fibrin has been 
removed. The washing is then repeated twro or three 
times with boiling alcohol, to extract fatty matters, and 
the residue is dried at 110° in an air-oven, until its 
weight becomes constant. It is then weighed between 
two wTatch glasses. 
The coagulated fibrin may also he washed by collect- 
ing it in a cloth of fine black silk, and tying the latter 
around it in a tight knot, as soon as the liquid has 
drained off. The mass is then well kneaded in a stream 
of water, and finally washed in hot alcohol; on opening 
the silk, the fibrin will be found almost white. By the 
aid of a small pair of forceps and a lens, the last parti- 
cles of fibrin may be removed from the silk, and placed 
directly in the watch glass in wdiich they are to be dried 
and weighed. 
Normal blood contains about 2.5 grammes of fibrin 
per kilogramme, the arterial blood being a little richer in 
fibrin than the venous blood. 
If it be desired to estimate the proportion of fibrin in 
a clot, the latter is divided into small portions, one of 
which is tied in a knot in a black silk cloth, and tho- 
roughly washed under a jet of wTater. When all except 
the fibrin is washed out, another portion of the clot is 
added, the washing continued, and the operation repeated 
until the whole of the clot has been converted into a 
white or nearly white mass. In order that no fibrin may 
be lost, the silk employed must be sufficiently fine. 
§ 179. If only a small quantity of blood is attainable, 
the proportions of wTater, of solid matters, and of mineral 
salts, may be estimated in part of the defibrinated blood, 
which must then be filtered directly from the fibrin, with- 
out addition of distilled water. In this case, three or 
four grammes of the defibrinated blood are rapidly 
weighed in a small porcelain capsule of which the weight 
when empty and dry has been accurately determined. 
The whole is then dried at 100-110° in an air oven, 
until it undergoes no further diminution in weight. 
O O 152 
BLOOD. 
From the weight of the residue, the proportion of solid 
matter in 1000 parts of the defibrinated blood is calcu- 
lated; then the proportion in the natural blood; and if 
the proportion of fibrin in 1000 parts of blood be added 
to the result so obtained, the sum will represent the total 
solid matter in 1000 parts of the blood; of course, 1000, 
less the total fixed matter, will represent the proportion 
of water in the blood. 
The residue in the porcelain capsule may now be 
calcined for the estimation of the mineral salts in the 
defibrinated blood, and their proportion in the natural 
blood is then found by a simjde calculation. 
The following example explains the method of calcu- 
lation. 
Estimation of fibrin. 
Weight of apparatus in which the blood is beaten, 
together with the blood ..... 71.471 grammes. 
Weight of apparatus alone . .... 33.840 “ 
Weight of blood .... = 37.631 “ 
Weight of watch glasses with the dry fibrin . 5.254 “ 
“ “ “ alone .... 5.165 “ 
Weight of fibrin . . . . = 0.089 “ 
TT .089x1000 0 oa .. . c 
Hence = 2.36 grammes, the amount or 
37.631 & 
fibrin contained in 1000 grammes of blood. 
Weight of porcelain capsule with defibrinated 
blood ........ 21.397 grammes. 
Weight of porcelain capsule alone . . . 17.865 “ 
Weight of defibrinated blood . . = 3.532 “ 
Weight of capsule with dry residue . . . 18.628 “ 
“ “ alone 17.865 “ 
Weight of residue . . . = 0.763 “ 
Esthnatlon of fixed matters, water, and mineral salts. 
1T 763 x (1000—2.36) 01„ nQ 
Hence >- = 216.08, the propor- 
O.Ooii ANALYSIS OF SERUM. 
153 
tion of solid matter in 1000 parts of blood, in addition 
to the fibrin. The total solid matter and water, are 
calculated by adding the fibrin and other fixed matters 
together, and deducting the sum from 1000. Thus— 
1000 parts of blood contain . . 2.36 parts of fibrin. 
“ “ “ . .216.08 “ other solid mat- 
ters. 
The total amount of solid matter = 218.44 
“ “ “ water = 781.56 
The capsule with the. residue after incineration 
weighs ........ 17.904 grammes. 
The capsule alone weighs ..... 17.865 “ 
The mineral salts in 3.532 grammes of defibrinated 
blood weigh ....... 0.039 “ 
Consequently, the mineral salts in 1000 parts of blood 
will equal 
.039 x (1000—2.36) _ _ 
Water ........ 781.56 
Fibrin ........ 2.36 
Mineral salts ....... 11.01 
Albumen and other solid matters (by difference) 205.07 
Analysis of Serum. 
ESTIMATION OF ALBUMEN, SALTS, ETC. 
§ 180. 4 or 5 grammes of serum are exactly weighed 
in a tared vessel, and poured into about 20 cubic centi- 
metres of boiling distilled water; the vessel is washed 
out several times with a little cold water, which is then 
added to the mixture of serum and water. By the aid 
of a glass rod, a few drops of acetic acid are added to 
the boiling mixture until the albumen coagulates in large 
flakes; care must be taken to use enough acid, and also 
to avoid an excess; if too small a quantity be employed, 
the albumen does not separate well, and in presence of 
an excess, the liquid remains milky, and part of the 
albumen may he redissolved. 
The mixture is then thrown on a filter, and the precipi- 
tate thoroughly washed with water, the filtrate and 
washings being retained for the subsequent estimation of 154 
BLOOD. 
soluble salts and extractive matters. The coagulated 
albumen is removed from the filter while still moist, 
which may readily be accomplished by the aid of a small 
spatula, and transferred to a small tared watch glass, 
dried at 100 or 110°, and weighed. 
The filtrate and washings may be evaporated to dry- 
ness in a small porcelain capsule on a water bath, and 
the residue dried at 100 or 110°, and weighed. This 
residue consists of soluble salts and .extractive matters; 
the former are estimated by cautiously igniting the 
mixture over a lamp, until the carbon is completely con- 
sumed, and weighing the ash. The proportion of soluble 
salts so found is deducted from the total mineral salts 
contained in the serum, as determined by another opera- 
tion, and the insoluble salts are thus estimated. 
§ 181. Hoppe-Seyler recommends the coagulation of 
the albumen by alcohol, the process being as follows: Be- 
tween 20 and 50 grammes of the serum are mixed with 
three or four times their volume of alcohol, and the mixture 
is allowed to stand in the cold for several hours. It is 
then filtered, and the precipitate washed, first with ab- 
solute alcohol, then with alcoholic ether, and finally with 
hot water, the liquids being collected separately. The 
albumen and insoluble salts alone are left upon the filter, 
provided the serum employed was quite clear. The 
liquids used for washing carry with them a small propor- 
tion of the albumen, which is subsequently coagulated 
and added to the first portion, as will shortly be indi- 
cated. The entire coagulated albumen is again washed 
with alcohol, to remove the water with which it is im- 
pregnated, and is then dried at 110°, and weighed. The 
residue is ignited in a porcelain crucible, and the remain- 
ing ash represents the insoluble salts of the serum. 
In washing the albumen, three liquids have been ob- 
tained ; (1) an alcoholic solution ; (2) an alcoholic-ethe- 
real solution ; (3) an aqueous solution. 
(1) is evaporated nearly to dryness on a water-bath, 
and the residue is mixed with solution (2) ; the whole is 
then filtered, and the insoluble portion is washed, first 
with alcohol, then with alcoholic ether, and finally with 
the aqueous solution (3), the filtrates being collected ANALYSIS OF SERUM. 
155 
separately as before. The residue is repeatedly washed 
with small quantities of water, and then consists of the 
albumen which was dissolved in the first operations. It 
is added to the albumen at first coagulated, or may be 
dried, weighed, and ignited in the same manner sepa- 
rately, if so desired. 
The aqueous solution (3) contains all of the soluble 
salts, except those which are soluble in alcohol and 
ether; it is evaporated to dryness, the residue is ex- 
posed to a temperature of 110° in an air-oven, and 
weighed. It is then ignited at a red heat, and again 
weighed. The final residue consists of soluble mineral 
salts, while the difference between the two weighings is 
attributed to extractive matter. 
The alcoholic-ethereal solution (2) contains urea, glu- 
cose, a little sodium chloride, cholesterin, fatty matters, 
and lecithine. It is evaporated at a temperature below 
70°, or better, in a vacuum. The residue is exhausted 
with ether, thrown on a filter, repeatedly washed with 
ether, and the washings are added to the ethereal extract. 
The filter is then broken, and the residue washed into a 
small capsule in which it is desiccated at 110°, and 
weighed. It is then incinerated, and again weighed. 
The ethereal solution is distilled in a small retort or 
flask, on a water-bath, and the residue is dried in the 
air-oven, and weighed as rapidly as possible. It is then 
treated with alcohol, and an alcoholic solution of potas- 
sium hydrate, and digested on the water-bath until all 
of the alcohol is expelled. The residue, consisting of a 
mixture of soaps, cholesterin, neurine, calcium phos- 
phoglycerate, glycerin, and potassium hydrate, is treated 
with water, and agitated with an equal volume of ether; 
after the latter has separated, it is decanted, and the 
treatment with ether repeated several times. The ethe- 
real liquids are united, and the ether distilled off in 
a small retort, the residue being evaporated to dryness. 
This residue consists of impure cholesterin; it is ex- 
hausted with a small quantity of absolute ether, the new 
ethereal solution is evaporated, and the residue dried 
and weighed. It is almost pure cholesterin. The aque- 
ous residue of the agitation with ether contains potas- 156 
BLOOD. 
sium soaps of the fatty acids, the excess of potassium 
hydrate, etc. It is evaporated to dryness, and the resi- 
due mixed with potassium nitrate and completely incine- 
rated in a platinum crucible. The mass is then ex- 
hausted with water, and an excess of nitric acid is added. 
The solution is evaporated to a small bulk, mixed with 
ammonium molybdate, and allowed to stand for about 
twelve hours; the yellow precipitate of ammonium phos- 
pho-molybdate is dissolved in dilute ammonia, and the 
solution is treated with magnesium sulphate, ammonia, 
and ammonium chloride, and set aside for twenty-four 
hours. The precipitate of ammonio-magnesium phosphate 
is then collected, dried, and converted into magnesium 
pyrophosphate by strong ignition. The weight of the 
pyrophosphate multiplied by 7.2748 gives the weight of 
the lecithine from which the phosphorus was derived. 
This method of Iloppe-Seyler permits the estimation— 
1) Of albuminoid matters and insoluble mineral salts. 
The difference between the weight of the impure albumen 
and that of its ash, is considered as the weight of the 
pure albumen. 
2) Of soluble mineral salts, these being represented 
by the united ashes of the aqueous and alcoholic solu- 
tions. 
3) Of extractive matters, soluble and insoluble in 
alcohol. 
4) Of extractive matter soluble in ether, with special 
estimations of cholesterin, fatty matters (by difference), 
and lecithine. 
The quantities thus found are calculated for 10C0 
parts of serum. 
According to Becquerel and Ilodier, 10 grammes of 
extractive matters of blood, including both fatty and 
soluble substances, contained— 
Serolin ........ 0.025 
Soaps of fatty acids ..... 1.400 
Cholesterin . . . . . . .0.125 
Sodium chloride ...... 3.500 
Soluble salts of sodium ..... 2.500 
Indefinite matters ...... 2.450 HEMOGLOBIN. 
157 
ESTIMATION OF HEMOGLOBIN. 
§ 182. The most practicable, and most exact method 
for the estimation of hemoglobin, consists in determining 
the proportion of iron in the ash of a known quantity of 
blood. The estimation of the iron is most rapidly effected 
by the volumetric method depending upon the oxidation 
of a ferrous salt by a standard solution of potassium per- 
manganate. 
About one gramme of pure potassium permanganate 
is dissolved in one litre of distilled water, and the exact 
strength of the solution is determined by the aid of a 
solution of ferrous chloride, made by dissolving one 
gramme of pure iron wire in hydrochloric acid in a 
narrow-necked flask, and diluting the liquid to one litre. 
lOc.c. of this solution, containing 10 milligrammes of 
iron, are measured into a beaker of about 150 c. c. capa- 
city, and the volume is made up to about 50 c. c. with 
distilled water. 
A burette provided with a glass stopcock is filled to 
the 0 division with the permanganate solution, which is 
then added drop by drop to the solution of ferrous chlo- 
ride, until the latter acquires a persistent rose-tint. The 
volume of permanganate required corresponds to 10 milli- 
grammes of iron. 
50 or 100 grammes of the blood in which the hemo- 
globin is to be estimated, are evaporated to dryness, and 
the residue is completely incinerated in a platinum or 
porcelain capsule. The ash is dissolved in dilute hydro- 
chloric acid, most of the free acid expelled by evapora- 
tion, and a few pieces of pure zinc are placed in the 
solution until the latter becomes entirely colorless ; in 
this manner the ferric chloride formed is reduced to 
ferrous chloride. The zinc is then removed, and the 
liquid is diluted to about 50c.c. with distilled water. 
The solution of potassium permanganate is then slowly 
added from the burette until all of the iron is converted 
into ferric salt, as is indicated by the rose-color of the 
solution. This rose-color gradually fades after a time, 
but this effect is not due to the oxidation of the iron. As 
the exact volume of permanganate required to oxidize 10 158 
BLOOD. 
milligrammes of iron is known, the amount of iron in the 
ash is easily calculated from the volume of permanganate 
required to oxidize its solution. The proportion of iron 
thus found, multiplied by 238.1, gives the proportion of 
hemoglobin; the latter compound, according to the analy- 
ses of Hoppe-Seyler, contains 0.42 per cent, of iron. 
This method is accurate, provided great care be exer- 
cised in the manipulation, and in originally determining 
the strength of the potassium permanganate solution. 
As the latter undergoes certain changes in time, its 
exact strength should he found shortly before the 
analysis. 
Example.—It is found that 6.2 c.c. of the perman- 
ganate solution are required to produce a persistent rose 
tint Avhen added to 10 c.c. of the ferrous chloride solu- 
tion, properly diluted as directed. Consequently, 1 c.c. 
of the permanganate will oxidize milligrammes of 
iron from the ferrous to the ferric condition. 
100 grammes of blood are evaporated and incinerated, 
the residue is dissolved in dilute hydrochloric acid, the 
solution reduced by metallic zinc, and then diluted to 50 
c.c. This liquid being titrated with the permanganate 
solution, it is found that 26.8 c.c. of the latter are re- 
quired to produce a permanent rose-color. But 6.2 c.c. 
of permanganate have been found equivalent to 10 milli- 
grammes of iron. 
Then 6.2 : 10 = 26.8 : x, or = 43.2 mil- 
6.2 
ligrammes of metallic iron are found in 100 grammes of 
blood. Hence, the latter contains 43.2x238.1, or 
X = 10.285 grammes of hemoglobin. 
0.42 ® ° 
Anatomical Analysis of Blood. 
§ 183. If freshly drawn blood be examined under the 
microscope before it coagulates, it will be seen to consist 
of a transparent, colorless fluid, in which float a multi- 
tude of small disks, having a pale yellow color. These ANATOMICAL ANALYSIS OF BLOOD. 
159 
are the red corpuscles to which the color and opacity of 
the blood is due ; their pale color under the microscope 
is caused by the fact that the rays of light pass through 
single corpuscles, and are spread over a large surface. 
The corpuscles of human blood have an average dia- 
meter of six- or seven-thousandths of a millimetre, and a 
thickness of about two-thousandths of a millimetre. They 
are nearly circular, and exhibit a slightly depressed or 
concave centre. They have a great tendency to agglome- 
rate together in rouleaux, like piles of coin (Fig. 54). 
Fig. 54. 
Red blood-corpuscles. 
When placed in liquids of different densities, the cor- 
puscles undergo various changes in form and dimensions. 
In a solution having about the same specific gravity as 
their natural plasma, they remain unchanged ; a one per 
cent, solution of common salt fulfils the required condi- 
tions, and such a liquid may be employed to preserve the 
form of the corpuscles in microscopic examinations. If 
the liquid be less dense than the plasma, for instance, if 
the corpuscles be placed in pure water, they gradually 
become distended and globular, and finally burst; if, on 
the other hand, the liquid have a greater density than 
the plasma, the corpuscles become wrinkled, and col- 
lapse. This latter change of form frequently takes 
place while fresh blood is being examined between two 
glass slides by the aid of the microscope, and is then due 160 
BLOOI). 
to' the gradual evaporation by which the surrounding 
liquid becomes concentrated (Fig. 55). 
Fig. 55. 
Fig. 56. 
Blood corpuscles undergoing collapse. 
White blood-corpuscles. 
In addition to the red corpuscles, the blood contains a 
much smaller number of white corpuscles, leucocytes, 
having somewhat irregular forms, and a granular appear- 
ance (Fig. 56). They are identical with the white cor- 
puscles of lymph, chyle, and pus. When treated with 
acetic acid, they become transparent, and are seen to 
contain one or more nuclei. 
The blood-corpuscles are dissolved and destroyed by 
strong alkaline and acid liquids, but, if blood has simply 
dried, the corpuscles retain their identity, and often, even 
after the lapse of years, they may be recognized by their 
form and properties (see farther on). 
The density of the red corpuscles is 1088, consider- 
ably greater than that of the plasma in which they float; 
according to Denis, the weight of the dry globules is to 
that of the water which they contain as 1 is to 1.8. 
Although the corpuscles are solid or semi-solid sub- 
stances, and only suspended in the plasma, they cannot 
be separated from the latter by filtration, for they readily 
pass through the pores of filter-paper, being exceedingly 
elastic, and able to change and reassume their form. The 
addition of a large proportion of a saturated solution of 
sodium sulphate or magnesium sulphate to the blood, DETECTION OF STAINS AND SPOTS. 
however, renders the corpuscles less elastic; their bor- 
ders become serrated, and the central depression more 
distinctly marked. The mixture may then be filtered 
through paper which has previously been moistened with 
a saturated solution of sodium sulphate, and the corpus- 
cles will remain on the filter. The mass may be washed 
with a saturated solution of sodium sulphate, drained as 
thoroughly as possible, and weighed. Of course, re- 
sults obtained in this manner are only roughly approxi- 
mate. 
Detection of Blood Stains and Spots. 
§ 184. It is frequently necessary, in medico-legal in- 
vestigations, to determine whether spots upon clothing, 
or other fabric, or upon articles of furniture, wood, or 
instruments with which it is supposed a crime has been 
committed, are or are not due to blood. Sometimes it 
is also required to distinguish between human blood and 
that of another animal, but in this case the question can 
only be. considered by a skilled microscopist, and one 
who has long and carefully studied the forms and dia- 
meters of the blood-corpuscles of different animals, and 
the crystals which may be obtained from different kinds 
of blood. 
In most cases, however, it is not difficult to decide 
simply whether the spots be due to blood, unless they 
have been mixed Avith materials which profoundly modify 
the nature of the constituents of blood. 
The detection of blood is effected by microscopical 
examination, and by chemical tests. 
The microscopic examination depends upon the identi- 
fication of the red corpuscles. It is, therefore, neces- 
sary to bear in mind the modifications which these cor- 
puscles undergo under the action of different reagents. 
Water causes them to become spherical and transparent, 
by swelling them and dissolving their coloring matter. 
Hence the spots should never be washed with water 
before the microscopic examination. As has already 
been mentioned, they are altered and destroyed by acids, 
alkalies, chloroform, ether, etc. 162 
BLOOD. 
In order to restore the characteristic forms of the 
corpuscles in dried blood, the spot is moistened with a 
liquid whose specific gravity is about that of the plasma, 
and which will preserve the corpuscles. An artificial 
serum may he made by dissolving 30 grammes of white 
of egg and 40 centigrammes of sodium chloride in 270 
grammes of distilled water; or a solution containing 5 or 
6 decigrammes of either sodium chloride or sodium sul- 
phate in 100 grammes of water, may he employed. The 
part of the fabric, paper, wood, or other material con- 
taining the spot, is cut out, and soaked in a few drops of 
one of the above liquids in a watch-glass, or directly on 
a microscope slide. The glass is then covered, and 
allowed to stand until the spot is entirely softened; but 
little time is required if the stain he recent, but, if it be 
very old, a day or two may be necessary. 
When the spot seems completely disintegrated, the 
liquid is examined by the aid of a microscope, a high 
power being employed. When the blood has not long 
been dried, sufficient red corpuscles may always be ob- 
served to render their identification easy and 'certain, 
but in old spots only a few corpuscles are generally 
found, the greater number having been destroyed by the 
desiccation. The corpuscles recovered from dried blood 
sometimes present their normal color, form and diameter, 
sometimes they are almost colorless, nearly spherical, or 
shrunken and serrated on the edges, and smaller than 
when in the normal condition. Hence it is often impos- 
sible to identify the animal from which the blood was 
derived. 
However, while the microscopic examination may be 
indecisive, owing to the desiccation and destruction of 
the blood-corpuscles, the application of certain chemical 
tests will generally remove all doubt upon the nature of 
suspected blood-stains. 
The tests depending upon the detection of albuminous 
matter and of iron and ammonia in the spots, may be 
used, if desired, as corroborative evidence, as may the 
reaction with tincture of guaiac, but these tests are not 
conclusive, and could not be relied upon alone. It is DETECTION OF STAINS AND SPOTS. 
not so with the tests by the aid of which, hemoglobin 
and hematin are recognized; nor with the hemin test, by 
which crystals of the latter body are obtained. 
§ 185. Detection of hemoglobin and of hematin.—The 
absorption bands of oxyhemoglobin are usually apparent 
in the absorption spectrum of blood, when the latter is 
comparatively recent. The dried blood, or the part of 
the fabric, wood or other material bearing the stain, is 
digested with water containing a few drops of ammonia. 
When the liquid takes up no more coloring matter, it is 
filtered, if necessary, and introduced into a narrow little 
glass trough having parallel sides, which is then placed 
before the spectroscope; a ray of direct solar light is 
then caused to traverse the liquid and enter the slit 
(made quite narrow) of the spectroscope. If the dark 
bands characteristic of oxyhemoglobin be visible, no 
doubt can exist as to the nature of the liquid under ex- 
amination, but if the bands be not seen, a thicker layer 
of the liquid should be examined in the same manner. 
This may be effected by pouring the solution into a 
fiat-sided bottle, and placing this before the spectroscope. 
It has also been recommended to evaporate some of the 
liquid to dryness in a rather flat watch glass, over sul- 
phuric acid in a vacuum, and to examine the absorption 
spectrum of the residue. 
If no absorption bands be seen, the ammoniacal liquid 
is acidulated with glacial acetic acid, and agitated with 
its own volume of ether in a glass-stoppered bottle. If 
the ether do not separate readily, its separation may be 
effected by the addition of a few drops of glacial acetic 
acid. The ethereal liquid, which will have a brownish- 
red color, is then placed before the slit of the spectro- 
scope, and its absorption spectrum is examined; if 
hematin be present, the dark bands of hematin in acid 
solution are perceptible, especially a distinct narrow 
band in the red (see Fig. 28). 
According to lloppe-Seyler, and Dragendorff, a liquid 
containing of oxyhemoglobin, examined under a 
thickness of one centimetre, gives the absorption bands 
of oxyhemoglobin distinctly, provided the blood be fresh. 164 
BLOOD. 
The absorption spectrum of hematin is less sensitive, 
and shows no bands if the dilution be about 
In case the bands of oxyhemoglobin be well marked, it 
is not necessary to obtain those of hematin; but if the 
bands be poorly defined or somewhat displaced, the hemo- 
globin should be converted into hematin, and examined 
as directed. 
The spectroscopic tests are somewhat uncertain. 
Should the spot have dried in a position where it was 
completely exposed to the air, hemoglobin may be de- 
tected, even after the lapse of years; but if the coagula- 
tion and drying have taken place in the interior folds of 
a fabric, or other confined position, no characteristic 
bands may be obtained after two or three weeks. 
§ 186. Hemin crystals.—The property possessed by 
hematin of forming characteristic crystals when treated 
with acetic acid and sodium chloride, has already been 
studied (§ 89). The crystals are formed when fluid 
blood is dissolved in glacial acetic acid, and the liquid is 
evaporated to dryness. A magnifying power of about 
800 diameters is necessary for their identification; when 
prepared from fresh blood, they present the appearances 
shown in Fig. 57, while when obtained from old stains 
they resemble Fig. 58. (Naquet.) 
Fig. 57. 
Fig. 58. 
Iloppe-Seyler, Briicke, and Erdmann, have each pro- 
posed processes by which the crystals may be produced; 
in any case, the spots are detached from the objects 
bearing them, or if upon tissues, they are cut out by the 
aid of a pair of scissors; from iron or wood, they may 
be scraped by a sharp knife. DETECTION OF STAINS AND SPOTS. 
165 
Hoppe-Seyler then recommends that the matter be 
macerated in a little cold water, and when the latter has 
removed all of the coloring matter, the liquid is allowed to 
evaporate spontaneously in a watch-glass. The smallest 
trace of sodium chloride is added to the dried residue, 
which has a reddish-brown or brownish color, and the whole 
is mixed with six or eight drops of glacial acetic acid, by 
the aid of a slender glass rod. The glass is now gently 
warmed over a small flame, and the mixture is evapo- 
rated to dryness on a water-bath. The residue on the 
watch-glass is examined under the microscope. 
Briioke boils the suspected matter with a little glacial 
acetic acid, filters the liquid, adds a trace of sodium 
chloride to the filtrate, and evaporates it to dryness in 
a watch-glass, at a temperature below 80°. By this 
means, crystals may sometimes be obtained when Hoppe- 
Seyler’s method fails, as it may when the albuminous 
matter of the stain has been rendered quite insoluble by 
washing with hot water, previous to the examination. 
Erdmann’s process is, however, most satisfactory, and 
is that which is generally employed. The suspected 
matter is placed directly upon the microscope slide, a 
minute particle of sodium chloride added, and the whole 
is covered with a thin glass cover. A drop of glacial 
acetic acid is then placed upon the edge of the thin glass 
cover, so that it may penetrate to the substance by capi- 
larity. After several minutes, the slide is gently warmed 
by holding it at some distance above a flame, and from 
time to time it is examined under the microscope. When 
the liquid becomes sufficiently concentrated, crystals of 
hemin make their appearance. If no crystals be formed, 
another drop of acetic acid is placed on the slide, and 
the alternate warming and examination are repeated, 
care being taken that the acid is not caused to evaporate 
too rapidly. Only after several successive trials have 
failed to yield positive results, can it be decided that no 
blood is present. The small, colorless cubes of sodium 
chloride, which may form at the same time, are readily 
distinguished from the crystals of hemin, but it must be 
remembered that the smallest perceptible particle of 
sodium chloride is all that is required for the formation 166 
BLOOD. 
of hemin crystals, and that a larger quantity may cause 
the results to be less decisive. 
The form and color of the hemin crystals, together 
with the manner of their formation, are sufficient to 
characterize them ; if further confirmation be desired, it 
may be obtained by testing the crystals with water, 
alcohol, and cold acetic acid, in which they are insoluble, 
and by sodium hydrate, in which they dissolve immedi- 
ately. 
No hemin crystals can be obtained from putrid blood. 
The forms of hemin crystals differ as the blood from 
which they are obtained is derived from different ani- 
mals, so that it is quite possible to identify the animal 
by the character of the crystals furnished its blood. 
§ 187. In cases in which no hemoglobin, hematin, or 
hemin crystals can be detected, iron, albuminoid matters, 
and ammonia may be detected in stains ; but as has 
already been stated, these tests alone cannot be assumed 
to prove the presence of blood ; and, in the present state 
of the science, when either of the tests which have been 
described, especially the hemin test, yields affirmative 
results, it may be considered that blood was certainly 
present. The detection of the corpuscles is in itself con- 
clusive evidence. 
a) If the spot be wholly or in part soluble in cold 
water, as it will be should it not have been previously 
heated or submitted to the action of hot water, the aqueous 
solution loses its brown or red color when heated, and 
grayish flakes of coagulated albumen separate. These 
flakes are soluble in solutions of the alkaline hydrates, 
and the liquids so obtained act as other alkaline solutions 
of albuminoid bodies. 
b) If the spot be quite insoluble in cold water, it may 
be dissolved by a rather dilute solution of sodium hydrate, 
and on the careful addition of either acetic or nitric acid 
to this solution, a white precipitate of albumen is formed. 
The alkaline hydrate does not remove the coloring matter 
of the spot, and the solution will therefore be colorless. 
c) If the colored spot which has been treated with 
sodium hydrate, be extracted with hydrochloric acid, or 
if a portion of the original spot be detached and treated SEROUS LIQUIDS. 
167 
with hydrochloric acid, and the liquid be evaporated to 
dryness, a yellowish residue will be left; if this be dis- 
solved in a few drops of water, the solution will produce 
a blue color with potassium ferrocyanide, and a red 
color with potassium sulphocyanide, these reactions being 
due to tbe presence of iron in the residue. 
cl) The guaiac reaction is not characteristic, but may 
sometimes be serviceable as a confirmatory test. About 
one cubic centimetre of oil of turpentine which has been 
exposed to the air for at least several weeks, and has 
consequently become ozonized, is mixed with an equal 
volume of a dilute tincture of guaiac ; a little of the 
suspected matter is added, and the mixture is agitated. 
If any blood be present, the liquid assumes a blue color, 
and the matter which may be insoluble, is colored dark 
blue. 
SEROUS LIQUIDS. 
§ 188. The examination of serous liquids is very 
similar to that of the serum and plasma of blood, for 
while the latter fluids differ in some respects from serous 
exudations, in other respects they are quite analogous. 
All of the serous liquids contain albumen, and nearly all 
of them seem to contain at least two distinct albuminoid 
substances. 
They are more or less viscous, sometimes almost color- 
less and transparent, sometimes highly colored, opales- 
cent or even opaque. Certain of them, such as chyle, 
lymph, and pus, contain organized constituents, which 
may be recognized under the microscope. 
When globulin, or the fibrinoplastic substance, as well 
as fibrinogen, is present, they become thick and gelati- 
nous soon after they are removed from the body, and the 
fibrin which is deposited may be recognized by the char- 
acters already described ; when these varieties of albu- 
men are not present, the liquids usually remain fluid 
indefinitely. 
The following plan for the qualitative analysis of se- 
rous fluids is that proposed by Hoppe-Seyler. After SEROUS LIQUIDS. 
tlie presence or absence of the fibrin-forming substances 
has been ascertained by the spontaneous coagulation, or 
persistent fluidity of the liquid, a part of the latter is 
mixed with ten or twenty times its volume of water, a 
few drops of dilute acetic acid are added, and a current 
of carbonic acid gas is passed through the liquid. If a 
cloud be formed, and gradually augment, so that a fioc- 
culent precipitate is finally thrown down, the presence 
of a body analogous to globulin, or an alkaline albuminate, 
may be considered as demonstrated. 
Whether a precipitate be formed or not, the liquid is 
filtered, and the filtrate heated to boiling; the formation 
of a coagulum indicates the presence of ordinary albu- 
men, as it exists in serum of blood. 
The coagulum produced by carbonic acid gas is then 
separated from the greater part of the liquid in which 
it was formed, and divided into two parts; one part is 
treated with a concentrated solution of sodium chloride; 
if the coagulum be dissolved, it contains myosin; if it 
do not dissolve, it may consist of casein. The other part 
of the coagulum is treated with water containing one- 
tenth per cent. of hydrochloric acid; if the precipitate 
dissolve, it consisted of myosin, casein, or fibrin-forming 
substances. 
A part of the serous liquid is then mixed with a few 
drops of defibrinated blood, obtained by expression from 
clotted blood, and the whole is allowed to stand twenty- 
four hours in a warm place. If a gelatinous coagulum 
be formed during this time, fibrinogen was pi’esent in the 
liquid. 
Another portion of the liquid may then be treated with 
a little of the serous fluid obtained from hydrocele, or 
from the pericardium of the ox (containing fibrinogen), 
and if, after a day’s standing, the mass assume a gelati- 
nous consistence, or coagulate, the fibrinoplastic sub- 
stance (globulin) was present. 
Paralbumen is precipitated by acetic acid, but is com- 
pletely redissolved by an excess of that reagent. Its 
presence may be detected by mixing the liquid under 
examination with three times its volume of alcohol, col- 
lecting the precipitate, and redissolving it in water. If QUANTITATIVE ANALYSIS. 
169 
paralbumen be present, the liquid will become a viscous, 
jelly-like mass, after a longer or shorter interval, accord- 
ing to the proportion of paralbumen present. 
The separation and detection of the other possible 
constituents of serous liquids, are effected upon precisely 
the same principles applied for their detection in the 
blood. Tyrosine, leucine, urea, uric acid, lecithine, 
biliary matters, cholesterin, and sometimes glucose, are 
among these substances. 
Quantitative Analysis. 
§ 189. Estimation of avater and fixed matters.— 
TO or 20 c.c. of the fluid are exactly weighed in a tared 
porcelain capsule, and evaporated to dryness on a water- 
bath. The residue is then exposed to a temperature of 
100° in the hot-air oven, for several days, or until its 
Aveight becomes sensibly constant. The operation may 
be hastened by raising the temperature to 105 or 110°, 
after the desiccation has well advanced. 
The proportion of extractive matters and of mineral 
salts may then be estimated by successive extractions 
with water and alcohol, in a manner analogous to that 
followed in the analysis of blood (§ 180). 
§ 190. Albuminoid substances.—It is not often 
practicable to separate the albuminoid substances for 
their individual estimation; they are usually estimated 
together, and this may be most conveniently effected by 
boiling the liquid with a few drops of acetic acid, and 
collecting, drying, and weighing the coagulum. The 
boiling must be continued for some time, and the collected 
albumen must be washed, first, with a little water, then 
with boiling alcohol. The results are usually somewhat 
too low, owing to a small portion of the albumen which 
escapes coagulation. 
The method of Hoppe-Seyler (§ 181) for the estima- 
tion of albuminoid substances, fatty matters, salts, etc., 
in the serum of blood, is equally applicable to other 
serous liquids. 170 
SEROUS LIQUIDS. 
Special Serous Effusions. 
§ 191. The following analyses of some special serous 
effusions are given by Mehu, principally as the result of 
observations at the Hopital Necker. 
The examination of the effusion in fifty cases of acute 
pleurisy in male patients, gave a mean proportion of 
63.95 grammes of solid matter per kilogramme. Twelve 
similar cases in females yielded an average of 64.36 
grammes. In thirty-one additional cases (male and fe- 
male) the average solid matter was 65 grammes. From 
the history of these cases, jVIdhu draws the conclusion 
that a pleural effusion Avhose specific gravity is above 
1018, and which gradually coagulates, indicates an acute 
pleurisy, whose prognosis is more favorable as the co- 
agulum is more firm. If, on the other hand, the specific 
gravity is below 1015, the effusion depends upon an 
obstructed circulation in the heart or in the large vessels; 
in this case the average solid residue of the liquid falls 
below 50 grammes per kilo. A large proportion of fibrin 
generally indicates a favorable termination, but if the 
liquid be drawn off ten days or two weeks after its effu- 
sion, only a small amount of fibrin may be present, the 
greater part having separated spontaneously in the pleural 
cavity. When tapping is resorted to several times, the 
proportion of fibrin augments with each puncture if the 
disease tend toward recovery, but in the contrary case 
the proportion of fibrin remains about the same, or di- 
minishes. 
The same observer gives as the result of observations 
in TO cases of suppurative pleurisy, that notwithstanding 
the presence of a large proportion of pus, when the 
residue of solid matter in the filtered effusion, dried at 
100°, exceeds 60 grammes per kilo, there is great pro- 
bability of recovery, while if the solid residue fall below 
60 grammes per kilo, the prognosis is extremely grave. 
Liquid of hydrocele.—The effusion in hydrocele 
bears a great resemblance to serum of blood, but it does 
not usually contain fibrin. However, fibrinogen is al- 
Avays present, and the liquid coagulates spontaneously on 
the addition of a small quantity of the fibrinoplastic sub- SPECIAL SEROUS EFFUSIONS. 
171 
stance. The liquid of hydrocele is generally quite 
limpid, and may be readily filtered. In old effusions 
cholesterin is usually present, and sometimes in consider- 
able proportion. 
Of twenty-six of these liquids examined by M6hu, four 
contained less than 50 grammes of fixed matter per kilo, 
twenty-one contained between 50 and 100 grammes, and 
only one contained more than 100 grammes. 
The matter expectorated after thoracentesis is analogous 
to the pleural effusion, and sometimes even richer in 
solid matter. This is shown by the following analysis 
by Mehu of the liquid drawn from the pleural sac of a 
man 45 years of age, together with that of his expecto- 
rations of the day on which the operation was performed. 
Pleural liquid. 
Organic matter 52.44) , , , 
Mineral salts . 7.62 f 
Water .... 939.94 
Expectoration s , 
63.54 ? 7 0, 
11.50 $ 75'04 
924 96 
1000.00 
1000.00 
The expectoration of a serous liquid containing more 
than 70 grammes of fixed matter per kilo, should lead to 
the suspicion of a cyst of the liver, opening into the 
bronchia, especially if the liquid contain biliary pigment. 172 
PUS. 
PUS. 
§ 192. Normal pus is a more or less thick, creamy- 
looking liquid, having a yellowish or greenish color. It 
is not tenacious, and flows readily, thus differing from 
mucus, which it otherwise somewhat resembles. Its spe- 
cific gravity is about 1030, and its reaction usually neu- 
tral or alkaline. By filtration, it may be separated into 
two portions, one of which forms a limpid serum, while 
the other consists of solid corpuscles. 
The serum of pus contains coagulable albumen, iden- 
tical with that of the serum of blood, together with 
another albuminoid body which is precipitated on the 
addition of dilute acetic acid, and, by its behavior with 
hydrochloric acid and Avith sodium chloride, is closely 
related to myosin and fibrinogen. This substance has 
been called pyin; it may be obtained as a light-yellow 
solid, by adding very dilute acetic acid to the serum of 
pus. It is insoluble in acetic acid and in alcohol, but 
soluble in water. It constitutes but a small proportion 
of the solid constituents of pus ; after its separation, the 
ordinary albumen may be precipitated by saturating the 
liquid with sodium or magnesium sulphate, and heating. 
The serum of pus also contains mineral salts, choles- 
terin, leucine, urea, and glucose. (Hoppe-Seyler.) 
These substances may be extracted and detected as in 
the examination of any other serous liquid. The mineral 
salts consist principally of sodium chloride, and small 
quantities of alkaline phosphates and sulphates. 
The pus corpuscles or leucocytes may be separated 
from the serum by filtration, and this may be more readily 
accomplished after the addition of a solution which pre- 
cipitates them. A dilute solution of sodium sulphate or 
barium nitrate answers well, and precipitates the corpus- 
cles unaltered. On the contrary, sodium chloride con- 
verts them into a jelly-like mass. They contain albu- 
minoid and fatty matters, cholesterin, lecithine, and 
mineral salts. By treating them with very dilute hydro- 
chloric acid, thoroughly washing the residue with ether PUS. 
173 
and alcohol, and then digesting with gastric juice, a 
residue is obtained which contains substances that have 
been called nuclein and sulphonuclein. (Miescher.) 
Pus may in certain cases be mistaken for mucus, in 
urine, for example; the distinction may readily be made 
by adding a little potassium or sodium hydrate, which 
would completely dissolve mucus, while it renders pus 
thick and viscid. 
§ 193. Blue pus, pyocyanin.—Pus sometimes has a 
blue color, which is attributed to the presence of a pecu- 
liar coloring matter called pyocyanin. Fordos gives the 
following process for the preparation of this substance: 
The lint, or other matter saturated with the pus, is mace- 
rated for twenty-four hours in water containing a little 
ammonia, after which the greenish liquid is filtered, and 
agitated with chloroform. The chloroformic solution is 
decanted and the chloroform distilled off; the residue is 
then dissolved in a little water, which dissolves the 
coloring principle and leaves the fatty matters. After 
filtration, this new solution is agitated with chloroform; 
the latter is decanted and evaporated to dryness. The 
pyocyanin so obtained is not quite pure ; it is therefore 
treated with a little hydrochloric acid, with which it 
forms a red compound, insoluble in chloroform. The 
hydrochloric acid solution is allowed to evaporate to dry- 
ness spontaneously, and the residue is exhausted with 
chloroform which removes all of the foreign matters, 
leaving the compound of pyocyanin and hydrochloric 
acid. This is triturated with barium hydrate under a 
layer of chloroform, which takes up the pyocyanin set 
free, and leaves it in blue crystals after spontaneous 
evaporation of the solution. 
Pyocyanin crystallizes in microscopic needles and 
plates, which are freely soluble in water, alcohol, and 
chloroform, and less soluble in ether. Its solutions are 
colored red by acids, and the blue color is restored by 
the action of alkalies. The color is entirely destroyed 
by strong acids and by chlorine. 
§ 194. Under the microscope, the pus corpuscles ap- 
pear as small, granular, opaque bodies (Fig. 59 a) having 
different diameters, but generally larger than blood cor- 174 
PUS. 
puscles. They contain one or more variously formed 
nuclei, which become more apparent when dilute acetic 
acid is added (Fig. 59 6). When treated with liquids 
Fig. 59. 
Pus cells. 
of different densities, pus corpuscles behave in a similar 
manner to blood corpuscles, contracting in volume when 
the liquid is more dense than the serum of pus, and 
swelling, and sometimes bursting, in the contrary case. 
The chemical analysis of pus is conducted as that of 
any other serous liquid. If desired, the estimation of 
the constituents of the serum and of the suspended matter 
may be made separately. EXTRACTS OF THE MUSCULAR TISSUES. 
175 
EXTRACTS OF THE MUSCULAR TISSUES. 
§ 195. The following principles have been found in 
the liquid obtained by extracting the muscles with cold 
water: albumen, creatine, creatinine, xanthine, hypo- 
xanthine, carnine, uric acid, glucose, inosite, lactates, 
salts of the fatty acids, and mineral salts, principally 
alkaline chlorides and phosphates. 
It has been established that the muscular juices are 
alkaline during life, but as soon as cadaveric rigidity is 
manifested, or when the muscles are tetanized for a suffi- 
cient time, these juices become acid. The changes to 
which this difference in reaction is due, are not known, 
but the reaction is independent of the coagulation of the 
muscular plasma, which may indeed be coagulated with- 
out destroying the alkaline reaction, provided the experi- 
ment be made before cadaveric rigidity appears. 
According to Neubauer, the presence of creatinine in 
the muscles is not certainly proven, that substance being 
probably formed by a metamorphosis of the creatine by 
the processes adopted for its separation. Fresh muscles 
do not seem to contain glucose, but glycogen, which is 
converted into glucose either wffien the muscles are 
brought into activity, or when the reaction of the juices 
becomes acid. 
§ 196. Processes by which the substances present in 
extracts of the muscles may be detected, have been de- 
scribed in the first part of this work. The following 
method may be adopted for the separation and detection 
of creatine, uric acid, hypoxanthine, xanthine, and ino- 
site : — 
The flesh, freed from fat, nerves, and bloodvessels as 
perfectly as possible, is finely divided, and macerated for 
about an hour with five or six times its weight of cold 
water. The aqueous extract is then decanted, and re- 
placed by a smaller quantity of water; after some time 
this liquid is poured off, and the residue is strongly 
pressed in a cloth ; all of the liquids so obtained are 
united, and allowed to stand for a short time, after which 176 
MUSCULAR JUICES. 
any fatty matter that has separated is removed mechani- 
cally. The reddish and somewhat clouded liquid is then 
rapidly heated to the boiling point, allowed to cool, and 
strained through a cloth, in order to separate the coagu- 
lated albuminoid matters. The filtered liquid should be 
clear, only slightly colored, and will have an acid re- 
action. 
Concentrated solution of barium hydrate is then added 
until it produces no further turbidity, and the precipitate, 
which may contain uric acid, xanthine, and hypoxanthine, 
is separated by filtration and set aside. Carbon dioxide 
is passed through the filtrate, which is then heated to 
boiling, in order that all of the barium carbonate may be 
precipitated. This precipitate is united with that pre- 
viously obtained, and the filtered liquid is distributed in 
several small capsules, and concentrated at a low tem- 
perature on a water-bath. The pellicles which form on 
the surface of the liquid during evaporation, are removed 
and added to the former precipitates. 
When the liquid becomes somewhat thick in consist- 
ence, it is placed in a warm place, and allowed to evapo- 
rate spontaneously. Creatine gradually separates in short 
colorless needles ; these are separated from the mother- 
liquor by filtration or decantation, washed, first with a 
little water, then with a small quantity of alcohol, and 
finally recrystallized in water, as directed in § 57. An- 
other crop of impure crystals may be obtained by the 
spontaneous evaporation of the mother-liquor. 
For the detection of volatile fatty acids, the liquid 
from which the creatine has deposited is rendered 
strongly acid by dilute sulphuric acid, and any barium 
sulphate that is formed is separated by filtration. The 
filtrate is introduced into a small retort, and distilled at 
a temperature not above 150°, on a sand-bath. The 
distilled liquid is examined for the presence of formic, 
acetic, and butyric acids, as has been directed for the 
separation of those acids. (§ 9.) 
The residue of the distillation is repeatedly agitated 
with successive portions of ether, and the decanted 
ethereal solutions are united, and evaporated to a syrupy 
consistence on a water-bath. The residue is extracted MUSCULAR JUICES. 
177 
with alcoholic ether, and the ether driven out by the 
application of a gentle heat; the alcoholic liquid is 
mixed with a slight excess of milk of lime, heated to 
boiling, and filtered hot. On cooling, crystals of calcium 
lactate are gradually deposited, and are recognized as 
indicated in § 11. 
Any inosite present in the juice would he left in the 
acid solution remaining after the treatment with ether; 
this is mixed with boiling alcohol, and any precipitate 
that may be formed is separated either by decantation, 
filtration, or both combined. The inosite may then be 
sought in the filtrate. 
Uric acid, if present, is in great part contained in the 
precipitates produced by baryta-water, and in the pelli- 
cles removed from the surface of the original solution of 
creatine ; but a portion of it remains in the mother- 
liquor from the crystallization of the creatine, and may 
be precipitated by the addition of an excess of alcohol. 
This precipitate and the baryta residues are united, and 
treated with glacial acetic acid; after standing one or 
two days, any uric acid present crystallizes out, together 
with the xanthine. The uric acid may be recognized by 
its microscopic appearance, and, if the residue be treated 
with cold dilute ammonia, the xanthine will be dissolved, 
while ammonium urate will remain. The murexide test 
may then be applied to the residue; the ammoniacal 
solution of xanthine may be precipitated by ammoniacal 
silver nitrate, and the precipitate identified by the aid of 
the microscope. 
§ 197. The following process was devised by Neu- 
bauer, especially for the extraction and separation of 
xanthine arid hypoxanthine ; one or two kilogrammes of 
meat should be employed: The finely divided flesh is 
thoroughly mixed with about its own weight of water, 
and heated to 60°, on a water-bath; the mass is then 
strongly pressed in a cloth, and the residue is mixed with 
more water, and again pressed. The united liquids are 
rapidly heated to boiling, and the coagulated albumen is 
separated by straining through a cloth. The filtrate is 
allowed to cool, and is then treated- with basic lead ace- 
tate, as long as a precipitate continues to form, employ- 178 
MUSCULAR JUICES. 
ing, however, as slight an excess of the lead salt as pos- 
sible. The precipitate is separated by filtration, and if 
it be desired to test for uric acid or inosite, is reserved 
for that purpose, since it will contain those compounds, 
if present. The clear filtrate is freed from the excess of 
lead by a stream of hydrogen sulphide, and the solution 
is filtered from precipitated lead sulphide, and evaporated 
to a syrupy consistence on a water-bath. It is then 
allowed to stand for a few days, in order that the crea- 
tine may crystallize out. The crystals are separated on 
a small filter, and repeatedly washed with alcohol. The 
mother-liquor is united with the alcoholic washings, and 
the alcohol is expelled by concentration on a water-bath; 
when the bulk of the liquid is reduced to 100 or 200 e.e., 
ammonia is added until the reaction is decidedly alkaline, 
and the solution is precipitated by ammoniacal silver 
nitrate. The precipitate is thoroughly washed with 
ammoniacal water, first by decantation, and finally on a 
filter. It is then boiled with nitric acid of a density of 
1.1, until all has dissolved, except a trace of silver chlo- 
ride which may remain. The clear liquid is poured into 
a crystallizing dish, and allowed to stand ; in about six 
hours, the compound of hypoxanthine and silver nitrate 
separates, and is removed and treated with an ammonia- 
cal solution of silver nitrate, to remove free acid, after 
which it is suspended in boiling water, and decomposed 
by hydrogen sulphide. After the silver sulphide is 
separated by filtration, the solution is concentrated and 
will deposit pure hypoxanthine. 
The xanthine remains in the mother-liquor from wThich 
the hypoxanthine-silver compound has crystallized. This 
liquid is mixed with an excess of ammonia, and the pre- 
cipitate which forms is washed, suspended in boiling 
water and decomposed by hydrogen sulphide. The fil- 
tered liquid deposits xanthine. GLANDULAR JUICES. 
179 
JUICES OF THE GLANDULAR ORGANS. 
§ 198. The following are the substances which may 
usually be found in extracts of glandular tissues: albu- 
men, creatine, urea, uric acid, xanthine, hypoxanthine, 
leucine, tyrosine, cystine, taurine, glucose, inosite, lactic 
and succinic acids, volatile fatty acids, and mineral salts. 
Naturally, the constituents of different glands are not 
the same ; biliary acids and pigments may sometimes be 
found in the liver, and traces of copper may usually be 
detected in that organ. 
The analysis of the glandular organs may be effected 
by the process indicated for the analysis of muscular 
tissues. The following process is recommended by 
Staedler: — 
The organs are finely divided by trituration with 
coarsely powdered glass, and the mass is suspended in 
cold water, and strained through a cloth. The filtrate is 
freed from albumen by rapidly heating it to ebullition, 
and again passing through a cloth. The clear liquid is 
precipitated by basic lead acetate, the precipitate sepa- 
rated by filtration, and a current of hydrogen sulphide 
passed through the filtrate. After removing the lead 
sulphide formed, the liquid is evaporated to a syrupy 
consistence, and treated with strong, boiling alcohol. 
The solution is concentrated and allowed to crystallize ; 
leucine and tyrosine, and occasionally taurine, are thus 
obtained, and gelatin is sometimes left as a residue in- 
soluble in alcohol. The lead precipitate may contain 
uric acid, xanthine, hypoxanthine, inosite, cystine, and 
sometimes a little taurine and tyrosine. It is washed, 
suspended in water, decomposed by hydrogen sulphide, 
and the filtered liquid is evaporated to crystallization. 
Processes for the separation and identification of the dif- 
ferent compounds have been indicated in the first part of 
this vrork. 180 
BONE. 
BONE, TEETH, AND BONY STRUCTURES. 
§ 199. The study of the structural formation of bony 
tissues does not belong to chemistry, and is considered in 
works on histology. From a chemical point of view, bony 
tissue consists of two principal constituents, one of which 
is a mineral framework or skeleton, while the other is 
cartilaginous and consists of ossein. 
The mineral salts which enter into the composition of 
bone, are, in the order of their preponderance, calcium 
neutral phosphate, Ca3(P O4)2; magnesium neutral phos- 
phate, Mg3 (P O4)2; calcium carbonate, and small quan- 
tities of calcium fluoride. 
In addition to the substances mentioned, bones contain 
water, fatty and albuminoid matters, alkaline chlorides 
and sulphates, and a trace of iron; these, however, do not 
belong to the true bony tissue, but to the bloodvessels 
which penetrate the bones, to the cell walls of the osseous 
structures, and to the contents of the medullary canals 
and canaliculi. 
If bones be entirely immersed in very dilute hydro- 
chloric acid for a few days, at a low temperature (15 or 
16°), the whole of the mineral matter is dissolved, while 
the cartilage, or ossein remains, and retains perfectly 
the form of the bone. In this condition ossein has a 
yellow color, is transparent, and is flexible and elastic, 
but it becomes hard, horny, and somewhat brittle, when 
dried. When ossein is boiled with water, it is entirely 
converted into gelatin, the rapidity of the change being 
increased by operating under pressure, thus raising the 
temperature. 
If bones be treated with warm,dilute hydrochloric acid, 
carbon dioxide is disengaged in considerable quantity, and 
the bones become fissured, and split into fibrous laminae. 
By strongly calcining bone, all of the organic matter 
is destroyed, and a white, earthy residue, retaining the 
form of the bone, is obtained, in which the mineral con- 
stituents of the bone may be detected by the usual 
chemical tests. QUANTITATIVE ANALYSIS. 
181 
Quantitative Analysis. 
§ 200. In order that the result of the analysis may 
express the composition of true bony structure, a com- 
pact portion of bone should be chosen, and separated 
from the spongy parts by scraping with a chisel or sharp 
knife. The periosteum is then carefully removed, as 
well as all adhering fatty matters; the latter maybe 
completely separated by leaving the bone for some time 
in contact with ether. The bone is then broken into 
small fragments, either in a clean iron mortar, or by 
wrapping it in filter-paper and crushing it by the blows 
of a hammer. The fragments are inclosed in a clean 
muslin cloth, and the whole is suspended for several days 
in a vessel of distilled water, the latter being changed 
once or twice every twenty-four hours. In this manner 
all of the soluble salts, which do not form part of the 
true osseous tissue, are removed. The fragments are 
now drained, dried, and heated to about 140°, in an air 
oven, for several hours, after which they may be readily 
reduced to an impalpable powder. The latter is again 
heated to about 130°, until its weight, after cooling, be- 
comes constant. It is then ready for analysis. 
a) Estimation of carbon dioxide.—The simplest 
Fig. 60. 
and most readily constructed apparatus for the estima- 
tion of carbonic acid gas is represented in Figure 60. 182 
BONE. 
Two or three grammes of the dried and pulverized bone 
are accurately weighed, and introduced into the flask A, 
which should have a capacity of about 150 cubic centi- 
metres, together with a small quantity of distilled water. 
A test-tube, B, is then partly filled with hydrochloric 
acid, and carefully placed in the flask in an upright, 
or slightly inclined position. The pierced cork of the 
flask is provided with a chloride of calcium tube, C, 
destined to prevent the escape of moisture with the 
carbon dioxide disengaged. The apparatus is now accu- 
rately weighed, after which, by inclining the flask, the 
hydrochloric acid is caused to flow from the test-tube 
and mingle with the water. An effervescence immediately 
takes place, due to the decomposition of the calcium car- 
bonate, and carbon dioxide is eliminated. When the 
effervescence has ceased, the flask is heated on a sand- 
bath, until the liquid just begins to boil; it is then 
allowed to cool, and, when its temperature is reduced to 
that of the surrounding air, is carefully weighed. The 
loss of wreight indicates the amount of carbonic acid gas 
evolved from the powdered bone. 100 parts of carbon 
dioxide correspond to 227.27 parts of calcium carbonate. 
5) Estimation of calcium.—Two or three grammes 
of the powdered and dried bone are carbonized in a 
platinum or porcelain capsule, at as low a heat as will 
effect the carbonization; the black mass is exhausted 
with boiling dilute hydrochloric acid, the excess of acid 
is expelled by evaporation of the clear, filtered solution 
thus obtained, and the residue is diluted with water, and 
an excess of ammonia added. The precipitate formed is 
dissolved in the smallest possible quantity of acetic acid, 
which is added to the original liquid, and the solution is 
precipitated by the addition of ammonium oxalate. The 
calcium is thrown down as calcium oxalate, while the 
magnesium remains in solution. After standing twenty- 
four hours, the precipitate is collected on a filter, and 
thoroughly washed, the filtrate and washings being re- 
tained. The precipitate is dried on the filter, and con- 
verted into calcium carbonate by calcination. Since some 
calcium oxide is formed during the incineration, a few 
drops of a concentrated solution of ammonium carbonate QUANTITATIVE ANALYSIS. 
183 
are added to the residue, after the crucible has cooled, 
and the water and excess of ammonium carbonate are 
expelled by again heating to dull redness. The residue, 
consisting of calcium carbonate, contains 40 per cent, of 
calcium, or 56 per cent, of calcium oxide. 
c) Estimation of magnesium.—The magnesium phos- 
phate remains in the filtrate and wash-water from the 
calcium oxalate. This is treated with an excess of 
ammonia, which causes the precipitation of ammonio- 
magnesium phosphate MgNIPPO4. The mixture is 
allowed to stand twenty-four hours, in order that the 
precipitation may be complete, after which the precipi- 
tate is collected on a filter, washed with water containing 
a little ammonia, dried, and converted into magnesium 
pyrophosphate by strong ignition. 100 parts of magne- 
sium pyrophosphate Mg2P207, thus obtained,correspond 
to 36.06 parts of magnesium oxide. 
d) Estimation of phosphoric acid.—Part of the 
phosphoric acid which originally existed as calcium 
phosphate has been already precipitated in the estimation 
of magnesium. The remainder exists in the filtrate and 
wash-water from the ammonio-magnesium phosphate. 
This is mixed with ammonium chloride and magnesium 
sulphate, and, after standing twenty-four hours, the pre- 
cipitated ammonio-magnesium phosphate is collected, 
washed with ammoniacal water, and ignited as already 
indicated in the preceding paragraph. 100 parts of 
magnesium pyrophosphate correspond to 63.96 parts of 
phosphoric anhydride, P205; the proportion of phos- 
phoric anhydride precipitated in the estimation of mag- 
nesium phosphate is calculated from the weight of the 
magnesium pyrophosphate then obtained, and the quantity 
so found is added to that calculated from the last esti- 
mation. 
e) Estimation of organic matter.—The percentage 
of organic matter is indicated by the difference between 
100 and the sum of the mineral matters found in the bone ; 
this estimation may be controlled by strongly incinerating 
a small quantity of the powdered and dried bone in a 
platinum capsule. The residue is then moistened with a 
few drops of a saturated solution of ammonium carbonate, 184 
BONE. 
and again heated to dull redness. Its weight expresses 
the quantity of mineral matter, and should closely cor- 
respond with the sum of the inorganic constituents esti- 
mated separately. If desired, the proportion of fat may 
be estimated by exhausting a weighed quantity of dried 
and powdered bone, which has not previously been washed 
with either alcohol or ether, with strong ether, evapo- 
rating the ethereal solution, and weighing the residue, 
after drying at 100°. 
Calculation of the Analysis. 
We will suppose that 2.576 grammes of the powdered 
bone have yielded 0.081 gr. of carbon dioxide (1). 
2.651 grammes of powdered bone, treated as in b, have 
given 1.709 gr. of calcium carbonate (2); and from the fil- 
trate after precipitation of calcium oxalate (c), 0.071 gr. 
of magnesium pyrophosphate have been obtained by the 
addition of ammonia and incineration of the precipitate 
(3). In addition, the phosphoric acid remaining in the 
filtrate from the ammonio-magnesium phosphate, has 
yielded, when treated as in d, 1.053 grammes of mag- 
nesium pyrophosphate (4). 
Since 100 parts of CO2 correspond to 227.27 parts of 
calcium carbonate, 100 parts of the bone analyzed con- 
tain X 1Q0_ 3 14 parts of carbon dioxide; or the 
2.576 r 
bone contained — X per cent, of cal- 
100 F 
56 x 7 14 
cium carbonate, which contained— —— = 3.99 parts 
100 v 
of calcium oxide. 
From (2), since 100 parts of calcium carbonate corre- 
spond to 56 parts of calcium oxide, and since 2.651 gr. 
of bone have been found to yield 1.709 gr. of calcium 
carbonate, we deduce that 100 parts of the bone ana- 
lyzed would yield 64.46 parts of calcium 
carbonate; therefore the bone contains 
56 x 64.46_ 30.qc) per cent. of calcium oxide. 
100 F QUANTITATIVE ANALYSIS. 
185 
Since 100 parts of magnesium-pyrophosphate corre- 
spond to 36.02 parts of magnesium oxide, and to 63.96 
parts of phosphoric anhydride, (3) shows us that 100 
parts of hone contained x = 2.67, 
2.661 
2.67x36.06 n 07 , , . 
— =0.97 parts oi magnesium oxide. 
100 
Also, the 2.67 parts of magnesium pyrophosphate 
m i , 2.67x63.96 1 (_1 , , , . 
correspond to — = 1.71 parts ot phosphoric 
anhydride (5). 
The final determination of phosphoric acid (4) has 
shown us that 2.661 grammes of hone yield, in addition 
to the phosphoric acid precipitated in (3), 1.053 gr. of 
magnesium pyrophosphate. Then 
l_063xl00 = 39>T 25>40 of 
2.651 100 
phosphoric anhydride, plus the 1.71 parts before pre- 
cipitated, = 27.11 parts, are contained in 100 parts of 
hone. 
We thus far have found— 
Calcium carbonate ...... 7.14 
Calcium oxide (total) . . . . . 36.09 
Magnesium oxide . . . . . . 0.97 
Phosphoric anhydride ..... 27.11 
67.31 
The remaining 32.69 per cent, are considered to con- 
sist of fluorine and organic matter. 
But part of the phosphoric anhydride existed as mag- 
nesium phosphate, the remainder being in the form of 
calcium phosphate. Since 100 parts of magnesium oxide 
correspond to 118.33 parts of phosphoric anhydride, and 
to 218.33 parts of magnesium phosphate, 
iQ^—=al Par^s ie phosphoric anhydride 
originally existed as magnesium phosphate, of which the 
, 4. , 0.97 x 218.33 0 11 
bone contained --q - = 2.11 per cent. 186 
BONE. 
The remainder of the phosphoric anhydride existed as 
calcium phosphate. 100 parts of phosphoric anhydride 
correspond to 118.31 parts of calcium oxide, and to 
218.31 parts of calcium phosphate, Ca3(P04)2; hence 
100 parts of bone contain 
27.11—1.14 = 25.97 x 218.31 
= bb.b9 parts ot calcium 
100 1 
, , 25.97x118.31 
phosphate, corresponding to = 30.72 
parts of calcium oxide. 
The total percentage of calcium oxide found was 
36.09, of which 3.99 exists as carbonate, and 30.72 as 
phosphate. The difference between 36.09 and 30.72-f 
3.99 = 1.38, corresponds to the calcium fluoride present 
in the bone. 100 parts of calcium oxide correspond to 
139.46 parts of calcium fluoride, therefore 
x 92 per cent, of calcium fluoride. 
100 1 
The complete analysis of the mineral matter of the 
bone has thus yielded for 100 parts of bone— 
Calcium carbonate ...... 7.14 
Magnesium phosphate . . . . .2.11 
Calcium phosphate ..... 56.69 
Calcium fluoride ...... 1.92 
Organic matter (by difference) . . . 32.14 
100.00 
According to Heintz, by whom the preceding method 
of analysis was proposed, 100 parts of fresh bony tissue 
from the human femur, gave in two analyses—• 
I. ii . 
Calcium carbonate.... 6.36 6.45 
Magnesium phosphate . . . 1.23 1.21 
Calcium phosphate . . . 60.13 62.46 
Calcium fluoride .... 3.52 2.12 
Organic matter .... 28.76 28.76 
100.00 100.00 SALIVA. 
187 
SALIVA. 
§ 201. The saliva is the mixed secretion of the sub- 
maxillary, sub-lingual, and parotid glands, and of the 
smaller sub-buccal glands. It is a somewhat viscous 
liquid, slightly bluish, or opalescent in appearance. Its 
specific gravity varies between 1004 and 1006, and its 
normal reaction is alkaline. On standing, it deposits a 
sediment of epithelial matter derived from the mouth 
and salivary glands. 
Normal mixed saliva is essentially an aqueous solu- 
tion of albumen, mucin, fatty matters, a trace of potas- 
sium sulphocyanide, a peculiar ferment called ptyalin, 
and mineral salts, principally potassium and sodium 
chlorides, and alkaline and earthy phosphates. 
Urea has also been detected in the saliva in appa- 
rently normal conditions, and glucose, biliary pigments, 
lactic acid, and other substances, have been found patho- 
logically. Besides this, certain salts when administered 
internally rapidly pass from the blood into the saliva, 
and may easily be detected ; among these, the alkaline 
bromides and iodides, and the salts of mercury, are espe- 
cially prominent. 
Normal saliva yields a flocculent coagulum when 
boiled, or when treated with nitric acid, alcohol, lead 
acetate, tannin, mercuric chloride, etc. It is not affected, 
however, by the addition of either acetic, hydrochloric, 
or sulphuric acids, or by potassium ferrocyanide, or 
caustic alkalies. 
Ferric salts produce a blood-red color, due to the for- 
mation of ferric sulphocyanide. 
The ferment of the saliva, ptyalin, has the property 
of converting starch into glucose, and it may sometimes 
be of importance to determine whether the saliva is pro- 
perly active in this respect. For this purpose, a little 
boiled starch is made into a thin paste with water, and, 
after the addition of about one-third its volume of the 
saliva, is maintained at a temperature of about 35° (that 
of the body). In about fifteen minutes, a portion of the 188 
SALIVA. 
liquid is tested by Fehling’s solution, and the test may 
be repeated several times, at intervals of fifteen minutes, 
until satisfactory evidence of the presence or continued 
absence of glucose is obtained. 
After exposure to the air for several days, the saliva 
loses its property of converting starch into glucose. Con- 
cerning ptyalin, to which this property is generally at- 
tributed, little is positively known, but it seems to he 
closely allied to diastase, the peculiar ferment which is 
formed during the germination of barley and other grains. 
Its activity is destroyed by the presence of considerable 
proportions of either acids or alkalies, but is not affected 
in liquids only slightly acid or alkaline. 
Analysis of saliva.—As the chemical principles con- 
tained in the saliva are not numerous, the qualitative 
analysis may be confined to the tests for albuminoid 
substances, fatty matters, and mineral salts. The latter 
may be detected in the ash, but bromides, iodides, mercu- 
rial salts, etc., which have been administered internally, 
may be sought for in the saliva without any preparation. 
Abnormal substances, such as urea, biliary pigment, etc., 
are detected by the same processes described for the 
examination of urine and blood. 
The quantitative analysis of saliva may be limited to 
the estimation of water, total fixed matters, extractive 
matters soluble in alcohol, and mineral salts. The pro- 
portion of mucin and epithelial matter may be approxi- 
mately estimated by evaporating a weighed quantity of 
the liquid to a very small bulk, adding a few drops of 
acetic acid, and collecting the precipitated mucin and 
epithelial cells on a filter which has been dried at 100° 
and weighed. The mass is then -washed with a little 
water, and the residue dried at 100°, and weighed. 
Febrile conditions of the system do not seem to affect 
the relative composition of the saliva, although the secre- 
tion may be diminished or entirely suppressed. 
According to Iioppe-Seyler, the saliva secreted in 
icteric conditions of the system never contains biliary 
pigments, notwithstanding the contrary assertions of 
Wright ; and in cases of diabetes the saliva is acid, but 
never contains glucose. SALIVARY CONCRETIONS. 
§ 202. Salivary concretions.—Calculous concretions 
are occasionally formed in the salivary glands ; they 
consist principally of calcium carbonate and phosphate, 
together with an albuminoid substance. Such calculi 
may be analyzed by triturating them, and treating the 
powder with dilute hydrochloric acid, which dissolves 
the mineral salts and leaves the organic matter. The 
acid solution is evaporated to dryness, the residue heated 
to redness, and when cool moistened with ammonium car- 
bonate, again heated, and weighed after cooling. The resi- 
due consists of the mineral salts. Or, a weighed portion 
of the powder may be exhausted with boiling water ; the 
insoluble residue is dried on a fared filter and weighed; 
then incinerated, moistened with ammonium carbonate, 
again heated and weighed. In this manner the propor- 
tion of the substance soluble in water, the proportion of 
mineral salts, and that of organic matter, may be esti- 
mated. The proportions of calcium carbonate and phos- 
phate may be estimated in the ash. The deposits of 
tartar which . frequently form on the teeth, have about 
the same composition as salivary calculi, and are ana- 
lyzed in the same manner. 190 
GASTRIC JUICE. 
GASTRIC JUICE. 
§ 203. Gastric juice, obtained by mechanical irritation 
of the empty stomach by an inert body, is an almost 
transparent, and nearly colorless liquid. It is not viscid, 
and may be easily filtered. It has an acid taste, and a 
peculiar characteristic odor. Its specific gravity is very 
little higher than that of water, ranging from 1001 to 
1010. Its reaction is strongly acid, and in this respect 
it differs from the other secretions. 
The essential chemical elements of gastric juice are 
hydrochloric acid, and a nitrogenized organic substance 
which is soluble in water, and to which the name pepsin 
has been given ; this is the ferment of the gastric juice. 
There are also present certain mineral salts, notably 
potassium, sodium, ammonium, calcium, and magnesium 
chlorides and sulphates, ferrous chloride, and calcium 
and magnesium phosphates. Under certain conditions, 
particularly in diseased conditions of the system, lactic, 
acetic, and butyric acids, have also been detected in tbe 
gastric juice ; their presence may frequently be demon- 
strated in vomited matters. 
Potassium iodide, potassium sulphocyanide, salts of 
iron, and glucose, injected into the veins, pass into the 
gastric juice. 
Partially digested albuminoid bodies, called peptones, 
are nearly always found in gastric juice ; they are 
formed by the action of the juice on ingested matters, 
or perhaps on the substance of the gastric glands. 
The activity of the gastric juice, its power of convert- 
ing albuminoid bodies into soluble peptones which may 
be easily digested, is due to the combined action of pep- 
sin and hydrochloric acid. Neither of these substances 
alone is capable of digesting albumen ; when gastric 
juice is exactly neutralized by an alkali, it becomes in- 
active upon albuminoid bodies; and while water contain- 
ing from one-twentieth to one-tenth of one per cent, of 
hydrochloric acid will dissolve certain albuminoid bodies, 
the solution so obtained is entirely different from that GASTRIC JUICE. 
191 
which results from the digestion of albumen in a similar 
liquid containing pepsin. It must be remembered that 
the gastric juice does not only dissolve albumen, but 
modifies it (apparently by hydration), converting it into 
peptone. Thus, white of egg, which does not coagulate 
in the stomach, being soluble, is not, however, digestible 
without the aid of an acid, and its complete digestion 
requires a longer time than that of fibrin, or even of 
coagulated albumen. 
Gastric juice i3 precipitated by the addition of alcohol; 
the precipitate is soluble in water, and the solution ac- 
quires active digestive properties when treated with a 
drop or two of hydrochloric acid. 
ANALYSIS OF GASTRIC JUICE. 
§ 204. The detection of the various constituents of 
gastric juice may be effected by means which have 
already been described when treating of these con- 
stituents individually. 
The proportions of water, solid matter, and mineral 
salts, are estimated precisely as in the case of serous 
liquids, the saliva, etc. 
Estimation of the Degree of Acidity and of Free 
Hydrochloric Acid. 
The total acidity of the gastric juice is determined by 
the aid of a decinormal solution of sodium hydrate, the 
operation being performed as in the estimation of the 
degree of acidity of the urine. 
G. Schmidt first established the fact that the acidity 
of gastric juice is due to hydrochloric acid, employing 
the following process :— 
A weighed quantity of the previously filtered juice is 
acidulated with nitric acid, and all of the chlorine is 
precipitated by adding solution of silver nitrate. The 
silver chloride formed is collected on a filter, thoroughly 
washed, first with dilute nitric acid, then with pure 
water, and finally dried, fused, and weighed. The 192 
GASTRIC JUICE. 
weight of the filter-ash being deducted, the proportion 
of chlorine is calculated from that of the silver chloride. 
The filtrate and wash-water are united, freed from 
excess of silver nitrate by the addition of hydrochloric 
acid and subsequent filtration, and the filtered liquid is 
evaporated to dryness and the residue incinerated. The 
proportions of calcium, magnesium, potassium, sodium, 
and sulphuric and phosphoric acids contained in the ash, 
are determined by the usual methods of quantitative 
analysis. 
In another portion of the gastric juice, the ammonia 
is estimated by the process of Neubauer and Schloessing, 
as has been described for the urine. 
The potassium and sodium found are then calculated 
as combined with the sulphuric acid; and the other 
metals are calculated as chlorides and as acid phos- 
phates. The excess of chlorine must be considered to 
exist as free hydrochloric acid, and the proportion of 
hydrochloric acid so found corresponds with the degree 
of acidity of the gastric juice, as determined by the 
direct acidimetric method. 
The process is complicated, and requires perfect 
familiarity with the practice and calculation of analyses; 
when these conditions are fulfilled, the results obtained 
may be regarded as certain. 
From the results of analyses by this method, it fol- 
lows that hydrochloric acid is the normal acid of the 
gastric juice, and although other acids may be sometimes 
present, and have been detected by various observers, 
their presence must be regarded as either accidental or 
pathological. BILE. 
193 
BILE . 
§ 205. The color of the bile varies from pale-yellow 
to black ; it is generally viscous, and when agitated froths 
like a solution of soap. Its specific gravity is subject to 
great variations, but is usually comprised between 1026 
and 1082. It has a peculiar odor, and a persistent bit- 
ter taste. 
Human bile consists essentially of an aqueous solution 
of the sodium salts of taurocholic and glycocholic acids, 
cholesterin, fatty matters, biliary pigments, especially 
bilirubin, lecithine, and certain mineral salts ; sodium 
chloride, potassium chloride, sodium phosphate, calcium 
and magnesium phosphates, and sometimes traces of 
copper. Mucus from the gall-bladder is also present. 
It is probable that the phospho-glyceric acid and neu- 
rine, which may be detected in the bile, do not exist there 
as such, but are formed by the decomposition of lecithine. 
Bile which has begun to decompose contains cholic acid, 
produced by the breaking up of the glycocholic and tau- 
rocholic acids. 
Certain substances appear in the bile under patho- 
logical conditions ; they are urea, after extirpation of the 
kidneys, in cholera, and in Bright’s disease ; leucine and 
tyrosine, in diseases of the liver ; glucose, in diabetes 
mellitus ; blood, pus, and sometimes albumen. 
Normal bile is neutral or slightly alkaline ; it rapidly 
decomposes in the presence of the mucus it contains, and 
which seems to act as a ferment; but if this be precipi- 
tated by alcohol and removed, the bile may be preserved 
indefinitely. When evaporated, it becomes covered with 
a pellicle, similar to that which forms on the surface of 
milk under the same conditions. 
Bile is miscible in all proportions with water and alco- 
hol, but the latter first precipitates a flocculent deposit 
of mucus, more or less colored by the pigments present. 
Alkalies change the color of the bile, but acids produce 
precipitates. Neutral lead acetate throws down lead 
glycocholate, and if the liquid be filtered, lead taurocho- 194 
BILE. 
cholate may be precipitated by the addition of tribasic 
lead acetate to the filtrate. 
When bile is agitated with several times its volume of 
chloroform, it is partly dissolved by the latter liquid, and 
if the solution be decanted and allowed to evaporate, 
crystals of bilirubin and cholesterin are deposited. 
The extraction and properties of the biliary acids and 
pigments have already been studied. 
Biliary Calculi. 
§ 206. Biliary calculi are found in the gall-duct, gall- 
bladder, and occasionally in the intestines. They are 
sometimes small, and may then exist in considerable 
number; sometimes they attain a diameter of two or 
more centimetres. In shape, they may be nearly round, 
or irregular and polyhedral. They are usually of a light- 
brown color, and are greasy to the touch, and so soft 
that they may be readily crushed. 
They consist either of nearly pure cholesterin, of 
biliary pigments, or of both substances together, sometimes 
arranged in concentric layers. It is not unusual to meet 
with gall stones of which the interior is pure choles- 
terin, while the exterior layers are brown and contain 
biliary pigment together with some mineral salts. 
A calculus consisting of cholesterin presents, on being 
cut or broken, a brilliant, white, radiated structure. 
Pigment calculi also frequently show radiated struc- 
tures, but their color is variable, the same stone some- 
times having layers of different colors. The pigments 
are not deposited in the free state in calculi, but are com- 
bined with earthy bases, and accompanied by calcium 
and magnesium carbonates. 
§ 207. Analysis.—A portion of the calculus is pul- 
verized, weighed, and dried at 100 or 110°, in an air- 
oven, until its weight becomes constant. The loss of 
weight indicates the proportion of water. The dried 
powder is then exhausted with a small quantity of boiling 
water, which removes any bile that might be present; its 
quantity, usually very small, is given by the weight of 
the residue left after the evaporation of the aqueous solu- BILIARY CALCULI. 
195 
tion. The powder is again dried, and exhausted with a 
mixture of equal volumes of strong alcohol and ether. 
The ethereal extract is evaporated, and the residue, con- 
sisting of cholesterin, is dried at 100°, and weighed. 
The new residue, from which all cholesterin has been 
removed, is dried, weighed, and treated with dilute hydro- 
chloric acid, which dissolves out the earthy phosphates 
and carbonates, and sets free the coloring matters. The 
acid solution, separated by filtration, may be examined, 
if desired, for the metals present. The loss of weight of 
the dried residue of the hydrochloric acid extraction, in- 
dicates the proportion of mineral salts present, Avhile the 
residue itself represents the biliary pigments and mucus. 
If it be desired to separate the pigments, the residue is 
exhausted with chloroform, the liquid is decanted, and 
the chloroform separated by distillation: the residue of 
the distillation is treated with a mixture of absolute 
alcohol and ether, which leaves the bilirubin unchanged, 
and dissolves bilifuscin. The residue remaining after 
the extraction by chloroform, contains biliprasin, and 
yields it to alcohol. All of these solutions leave their 
respective pigments, in a more or less pure state, when 
they are evaporated to dryness. 
The residue of the last extraction consists of mucus, 
possibly albuminoid matters, and bile pigments which 
have undergone alteration and become insoluble. 
The hydrochloric acid solution obtained should be 
eyaporated to dryness, the residue calcined, and then 
dissolved in very dilute hydrochloric acid. If hydrogen 
sulphide be passed through this solution, a black pre- 
cipitate is often formed, and may be shown by further 
examination to consist of copper sulphide. As before 
mentioned, traces of copper have occasionally been de- 
tected in bile. MILK. 
MILK. 
§ 208. Milk is essentially an aqueous solution of lac- 
tose, together with certain mineral salts, holding in sus- 
pension very small fatty particles and, either suspended 
or in solution, an albuminoid body known as casein. It 
has a specific gravity of about 1030, subject to consider- 
able variation. Its reaction is generally alkaline shortly 
after its secretion, hut gradually changes to acid by the 
formation of lactic acid. Sometimes, however, milk is 
acid at the moment it is drawn; this is said to he usually 
the case with asses’ milk, and frequently with cow’s 
milk. Normal woman’s milk is always alkaline. 
Milk is coagulated by most acids, mineral and vege- 
table, especially by the aid of heat. Milk which has 
been saturated with boric acid may be preserved indefi- 
nitely in the cold, and will not coagulate ; hut it at once 
coagulates when heated. Some salts, such as zinc chlo- 
ride and calcium sulphate, have the property of coagu- 
lating milk. Lactic acid alone does not coagulate milk 
in the cold, unless it he present in considerable quantity, 
but acetic acid soon produces the coagulation, especially 
when aided by heat. Hence, milk may become sour by 
the natural formation of lactic acid, but does not usually 
thicken until acetic acid makes its appearance in the 
liquid. Rennet, wThich is prepared from the fourth 
stomach of the calf, coagulates milk with remarkable 
facility. 
When allowed to stand for several hours, the fatty 
globules which are suspended in milk gradually rise to 
the surface, and constitute cream. But the cream does 
not consist wholly of fat globules, nor does it contain all 
the fat of the milk. The opaline or bluish layer imme- 
diately belowT the cream, contains the greater part of the 
casein, lactose, and salts. 
The composition of cream is subject to as great varia- 
tions as that of the milk from which is is derived. The 
following are the results of six analyses of cream, by 
Mr. Wanklyn of London. CHEMICAL ANALYSIS. 
197 
I. II. III. IV. v. VI. 
Water 72.2 71.2 66.36 60.17 53.62 50.0 
Fat 19.0 14.1 18.87 33.02 38.17 43.9 
Casein, lactose, salts 8.8 14.7 14.77 6.81 8.21 6.1 
The composition of milk varies greatly, not only in 
different animals of the same species, but in the same 
individual, changing with the age, health, with the time 
of the day at which the milk is drawn, and even with 
the stage of the milking: the first portions of milk drawn 
are usually much more aqueous than the last. 
The substances of which the proportions should be es- 
timated in a quantitative analysis of milk, are water and 
fixed matters, mineral salts, fat (butter), casein, and 
lactose. The analysis should also lead to the detection 
of adulterations, should such be suspected. 
Density.—The density of normal cow’s milk is about 
1030, but may vary from 101§ to 1040. However, if 
the animals be in good condition, the density of unskimmed 
milk should not fall below 1029; while should the cream 
have been removed, the density should he 1033. The 
specific gravity of natural milk may be stated to be com- 
prised between 1029 and 1034. Any considerable varia- 
tion from these limits should give rise to the suspicion 
of adulteration. The specific gravity is determined by 
means of a hydrometer, and the temperature of the milk 
at the time of the observation should be 15°. Should 
it be higher or lower than this, one degree of the hy- 
drometer or lactometer is added or subtracted for every 
5° in temperature above or below 15°. 
Chemical Analysis. 
§ 209. Various methods have been devised for the 
chemical analysis of milk. In principle they are alike, 
but the modes of operation differ in some respects. 
Proportion of water and of fixed substances.— 
The complete evaporation of milk and analogous fluids 
requires care and patience. The liquid cannot he boiled, 
for as it becomes thick and concentrated, portions would 
be projected from the vessel, thus occasioning loss of 
substance and erroneous results. The desiccation may 198 
M ILK. 
be accomplished either in a vaccuum, or under a bell-jar 
over sulphuric acid; but the time required by such a 
method excludes it from practical application in the ma- 
jority of cases. No other resource is then left than the 
hot-air oven. 
10 c.c. of the milk are weighed in a small capsule, 
preferably of platinum, and exposed to a temperature of 
100° in an air oven, until the weight of the residue be- 
comes sensibly constant. The capsule is then allowed 
to cool in a desiccator, and should be covered during the 
final weighing, since the residue is quite hygroscopic. 
When milk is evaporated, a tenacious film forms on 
its surface, and is re-formed as often as it is removed. 
The evaporation and drying may be much facilitated by 
breaking up this film, from time to time, with a small 
glass rod, or platinum spatula, which, when used, should 
always be weighed with the capsule. The results given 
by this method are quite satisfactory, although the resi- 
due has a yellow or brownish color, due to the action of 
the heat on the lactose and fatty matters of the milk. 
§ 210. Proportion of cream.—The proportion of 
cream is estimated by allowing about 200 c.c. of the 
milk to stand for twenty-four hours in a cylindrical jar 
about 42 millimetres in diameter and 10 centimetres 
high. The jar is graduated in one-hundredths, and is 
filled with milk to the 0° point, in about twenty-four 
hours, the depth of the layer of cream is read off, and the 
number of divisions it occupies, indicates its centesimal 
proportion. Normal cow’s milk thus treated shows 
between ten and fourteen per cent, of cream. 
Of course such a method is only approximate, and of 
no real value from a scientific point of view. As has 
been seen, cream varies greatly in composition, and it 
can hardly be satisfactory to determine the proportion of 
a matter whose composition is uncertain. However, the 
method may be useful in cases where it is suspected that 
part of the cream has been fraudulently removed. 
§ 211. Casein.—As has already been mentioned 
(§ 96), casein appears to be an alkaline albuminate ; it 
is precipitated from milk by the addition of acids, or of 
certain neutral salts. The recent researches of J. Leh- METHODS OF ANALYSIS. 
199 
mann seem to show that it does not exist in solution in 
milk, but in a state of suspension; thus when milk diluted 
with an equal volume of water is poured upon a porous 
tile, the aqueous portion is absorbed, while the casein 
and fat remain upon the surface, forming a tenacious 
film; Lehmann has applied this fact to the estimation of 
casein, as will be indicated farther on. 
Millon and Commaille’s Method of Analysis. 
§ 212. a) The proportion of water and fixed matter 
is determined precisely as already indicated, by evapo- 
rating a known quantity of the milk to dryness in a 
platinum capsule, either in an air-oven at 100-110°, or 
in a vacuum over sulphuric acid, until the weight of the 
residue becomes sensibly constant. 
b) Casein, fat, and albumen.—20 c.c. of the milk, 
previously well agitated to insure homogeneity, are 
diluted to 400 c.c. with distilled water. Very dilute 
acetic acid is added, drop by drop, to the mixture, until 
a flocculent precipitate appears, and a current of washed 
carbon dioxide is then passed through the liquid for a 
quarter or half an hour. After standing for about 
twelve hours, the precipitate is collected upon a filter, 
which has been dried at 100° and weighed, and washed 
with distilled water. It is then dried at 100°, and 
weighed. The weight of the precipitate multiplied by 
5, gives the weight of the casein and butter in 100 c.c. 
of milk. 
The quantity of albumen is determined by boiling the 
filtrate, together with the washings from the casein, for 
a short time, collecting the coagulated albumen upon a 
tared filter, washing with water, and drying it at 100° 
until its weight becomes constant. 
c) Lactose.—The lactose is contained in the last fil- 
trate and washings. These are united, the volume of 
the mixture is exactly measured, and a 50 c.c. burette 
is filled to zero with the liquid. 
20 c.c. of Fehling’s solution (see §§ 23 and 158) are 
then diluted to 100 c.c. with distilled water, and heated 
to boiling. As soon as the liquid is in full ebullition, 200 
MILK. 
the solution to be analyzed is slowly added until all of 
the copper is reduced. The operation is conducted pre- 
cisely as has been described for the estimation of glu- 
cose in urine ; however, while 10 c. c. of Fehling’s solu- 
tion would be reduced by 50 milligrammes of glucose, 
the same quantity of the cupric solution will require 67 
milligrammes of lactose. Hence the 20 c. c. employed 
correspond to 134 milligrammes of lactose. 
Suppose that the total volume of the filtrate and wash- 
water obtained after the coagulation of the albumen be 
550 c. c., and that 82 c.c. of this be required for the 
reduction of 20 c.c. of Fehling’s solution ; these 82 c.c. 
must have contained 134 milligrammes of lactose; hence— 
_ whence milligrammes, the 
quantity of lactose contained in 550 c. c. Since the 
latter correspond to 20 c. c. of milk, 100 c. c. of milk 
analyzed contain 898 x 5 = 4.490 grammes of lactose. 
d) Butter.-—20 c.c. of milk are well mixed with 
about an equal volume of a not too concentrated solution 
of sodium hydrate, and the mixture is agitated with 60 
or 100 c. c. of ether. After the ether has separated, it 
is decanted into a tared vessel, and the still milky aqueous 
liquid is agitated with a fresh portion of ether, which is 
then decanted and added to the first portion. The treat- 
ment with ether is continued until a drop of the ethereal 
extract leaves no fatty residue when allowed to evapo- 
rate upon a watch-glass. The united ethereal solutions 
are then evaporated at a gentle heat, and finally dried 
in an air-oven at 110°, and weighed. The weight of 
the residue multiplied by 5, gives the quantity of butter 
in 100 c. c. of the milk. By subtracting this weight 
from that of the casein and butter, as first found, the 
quantity of casein is estimated. 
e) Mineral salts.—The residue obtained in a is 
cautiously heated until it is completely carbonized ; if 
it be heated too rapidly, a portion will be projected from 
the capsule by the swelling of the mass. The charcoal 
is then exhausted with the smallest possible quantity of 
boiling water, and the liquid is filtered through a filter 
of which the weight of the ash is known. The capsule METHOD OF CHEVALIER AND HENRY. 
201 
and residue are washed with boiling water, which is also 
passed through the filter. The filtrate is evaporated to 
dryness in a small tared capsule, and the residue is 
heated to incipient redness. Its weight is that of the 
soluble mineral salts. The filter and its carbonaceous 
contents are ignited in a platinum capsule or crucible, 
until the carbon is completely consumed. The weight 
of the residue, less that of the filter ash, is the weight 
of the insoluble salts. 
It may be objected to the process of Millon and Com- 
maille, that it estimates as albumen a portion of the 
casein which is not entirely precipitated except under 
the influence of heat. Indeed, if the whey obtained by 
the action of rennet on milk be saturated with sodium 
chloride, and then mixed with five or six times its volume 
of alcohol, no precipitate is formed ; under the same cir- 
cumstances, a dilute solution of albumen yields an abun- 
dant coagulum. Doybre, Millon, and others have main- 
tained the presence of albumen in milk, because after 
the casein has been separated by the addition of acetic 
acid, a coagulum may yet be obtained on heating the 
clear liquid. This only shows, however, that all of the 
casein is not precipitated by acetic acid alone without 
the aid of heat. Hence it would probably be more exact 
to boil the liquid after the addition of acetic acid, and to 
estimate the entire precipitate as casein, the filtrate be- 
ing used for the estimation of lactose, as before. 
Method of Chevalier and 0. Henry. 
§ 213. A measured volume of the milk is boiled, and 
treated while boiling with a little acetic acid diluted with 
twice its volume of water. The precipitate is collected 
on a filter, washed with water, and then exhausted with 
ether. The ethereal solution is evaporated to dryness, 
and the residue gives the weight of butter; the casein 
remains on the filter, together with insoluble salts ; it 
is dried at 100°, and weighed. It is then incinerated 
with the filter, and the proportion of insoluble salts thus 
found is deducted from the weight of the precipitate, and 
the quantity of casein is so ascertained. The aqueous fil- 202 
MILK. 
trate and washings contain the lactose and soluble salts; 
the former is estimated by submitting a portion of the 
liquid to volumetric analysis by means of Fehling’s solu- 
tion. The soluble salts are determined by evaporating an- 
other portion of the liquid to dryness, lightly incinerating, 
and weighing the residue. 
O O 
Baumhauer’s Method. 
§ 214. A number of glass rings about 4 centimetres in 
diameter are made from slender glass rods, and two 
short straight pieces of rod are, at angles of about 60°, 
attached to the extremities of one diameter of each ring, 
one above, the other below, so that the ring will rest 
immovable in a horizontal position in a funnel. A 
circular filter 10 or 12 cm. in diameter is folded, opened 
into a cone, and placed in a ring. The filter is then 
filled with pure, dry, quartz sand, and may be supported 
in the ring without coming into contact with the sides of 
the funnel. The upper straight glass rod attached to 
the ring serves as a handle, by which the ring, with its 
filter filled with sand, may be removed from the funnel, 
and supported in the mouth of a small beaker, and 
weighed. This arrangement is more easily made than 
that originally employed by Baumhauer, which is repre- 
sented in Figure 61. 
As many rings are necessary as there are analyses to 
be madeeach should be supported in a funnel of which 
the beak is closed by a gum tube and spring clip, the 
top being ground, and covered with a glass plate (Fig. 
62). A filter so arranged, and filled with sand, is 
dried for half an hour at 100°, and weighed, together 
with its ring support. 10 c.c. of the milk to be analyzed 
are then slowly and carefully distributed over the sand, 
so that all of the fluid may be absorbed without 'wetting 
the paper. The whole is then transferred to an air oven 
heated to 105°, and dried until the weight of the system 
becomes sensibly constant. The difference between this 
weighing and the first, gives the sum of the solid con- 
stituents of the 10 c.c. of milk. Sand cools slowly, so 
that sufficient time must be allowed for the filter to cool B A L’MH AUER’S METHOD. 
203 
before weighing. The temperature of the air oven should 
be kept below 100° for four or five hours after the filters 
are first introduced, and then raised to 105° for another 
hour or tw7o. 
Fig. 61. 
Fig. 62. 
The filter with its contents is placed in one of the 
funnels, which is then filled with anhydrous ether, and 
covered for half an hour. After that time the ether is 
drawn off by opening the spring clip, and the opera- 
tion is repeated twice. The filters are finally washed 
twice, by pouring a little ether on them and allowing it 
to run through directly, and are then placed in the air- 
oven and dried. Each filter requires about 100 c.c. of 
ether. The difference between the weight of the filter, 
after treatment with ether, and the previous weighing, 
gives the proportion of butter present in 10 c.c. of the 
milk. For the estimation of lactose, the proceeding is 
the same as that indicated for butter, except that warm 
water, slightly acidulated with acetic acid, is substituted 
for the ether, and the filtrate is received in a 100 c.c. flask. 
About 90 c.c. of warm water should be used, in succes- 
sive portions, and, when this has run through, the filtrate 
is cooled to 15°, diluted to 100 c.c., and the amount of 
lactose present is estimated by Fehling’s solution. 204 
MILK. 
The filter and contents are again dried, cooled, and 
weighed, the difference between this weighing and the 
weight of the filter and sand, before the addition of the 
milk, representing the quantity of casein and of insoluble 
salts. The difference between the loss of weight after 
treatment with water, and the quantity of lactose found, 
represents the soluble salts. The total quantity of 
mineral salts, the remaining factor necessary for the 
estimation of casein and insoluble salts, is found by in- 
cinerating 10 c.c. of the milk in a platinum crucible, and 
weighing the ash. 
The method is very convenient when a number of 
analyses are to be made simultaneously. The results 
given by it are quite concordant, and may be regarded 
as satisfactory. It is not, however, absolutely accurate, 
owing to the slight solubility of casein in water. It is 
advantageous in the analysis of woman’s milk, since only 
20 c.c. of milk are required for the complete analysis. 
§ 215. Partial Analysis of Milk. 
a) VOLUMETRIC ESTIMATION OF LACTOSE. 
10 c.c. of Fehling’s solution are diluted with 30 c.c. 
of water, and heated to boiling in a flask or capsule. 
The milk to be analyzed is diluted with three times its 
volume of water, and added to the cupric solution directly 
from a burette. Or the milk may be coagulated by 
heating it with a few drops of acetic acid, and the clear, 
filtered whey may be diluted with three volumes of 
water, and used for the estimation of lactose. 
b) RAPID APPROXIMATE ESTIMATION OF BUTTER. 
Marciiand’s process.—This method of approximate 
analysis depends upon the fact that the fats are easily 
soluble in ether, and not very soluble in a mixture of 
equal volumes of alcohol and ether. 
The apparatus devised by Marchand, and called a lacto- 
butyrometer, consists of a glass tube about 10 millimetres 
in internal diameter, and HO centimetres long, closed at 
one end. The body of the tube is divided into three ESTIMATION OF BUTTER. 
205 
portions of equal capacity (Fig. 68). The tube is filled 
with milk up to the lower division, marked L; ether is 
then poured in up to E, and alcohol is 
finally added up to the line A. The' 
space E A is divided into ten equal 
parts, and the upper three divisions are 
marked on the glass and subdivided into 
tenths, which are called the degrees of 
the lacto-butyrometer. The subdivisions, 
equal to the degrees, are also extended 
above the line A. Each division or 
degree is equal to one one-hundredth of 
the space A E, or to one three-hundredth 
of the total capacity of the body of the 
tube. 
Ey Marchand’s original process, the 
milk, rendered homogeneous by agitation, 
is poured in up to the line L, made alka- 
line by a few drops of sodium hydrate, 
and the ether and alcohol are then added. 
C. Mdhu has modified the process by 
suppressing the use of sodium hydrate, 
and employing an alcoholic solution of 
boric acid. The modification appears to 
be an improvement, and the manipula- 
tion is then conducted as follows:— 
The tube is filled up to L with the 
milk, and then up to E with dry ether. 
It is then closed by means of an ordinary 
close-fitting cork, and agitated until the 
liquids are thoroughly mixed. Then, 
without waiting for the separation of the 
fluids, or paying attention to the con- 
traction in volume, alcohol saturated 
with boric acid is poured in up to the 
line A. The tube is then again closed, 
and vigorously agitated; the precipitated 
casein breaks up into fine flakes, and readily subsides to 
the bottom of the tube, only slightly retarding the sepa- 
ration of the butter. The still closed tube is then placed 
in a vertical nosition in a water bath heated to 40°. 
Fig. 63. 
Marchand’s Lacto- 
butyrometer. 206 
MILK. 
The butter gradually rises to the surface, and when 
its volume ceases to increase further, the number of de- 
grees it occupies is read off. 
The operation is precisely the same if the boric acid 
be omitted; a few drops of sodium hydrate are then 
added to the milk before pouring in the ether, but, al- 
though the butter sometimes separates more quickly under 
these circumstances, the result is not always satisfactory. 
Marchand states that at a temperature of 40°, milk 
must contain 12.60 grammes of butter per kilogramme 
in order to saturate with fatty matter the mixture of 
alcohol, ether, and milk. Hence any butter in excess of 
12.60 grammes per kilo, will be set free. The weight 
of this butter, x, is found by the formula x— 12.60 
gr. + 2.33 gr., n representing the number of degrees 
of the lacto-butyrometer occupied by the butter. While 
this method cannot be considered as exact, it is closely 
approximate, and is of special value in the examination 
of the quality of commercial milk. 
Marchand states that unskimmed milk treated by this 
method shows an average of 36.34 grammes of butter 
per kilogramme. The minimum quantity of butter al- 
lowed in the milk accepted by the hospitals of Paris, is 
fixed by law at 30 grammes per kilogramme, and good 
unskimmed milk should contain at least that much. 
According to the experiments of J. Lehmann, casein 
does not exist in a state of solution in milk. When milk 
diluted 'with an equal volume of water is spread on the 
surface of a porous tile, the casein and butter remain on 
the surface of the tile, while the whey, holding in solu- 
tion the lactose, the soluble mineral salts, etc., is ab- 
sorbed. After standing for one or two hours, the film of 
casein and butter may he perfectly detached by the aid 
of a thin spatula, dried at 105° for two hours, and 
weighed. The separation of the butter and casein is 
easily effected by ether. The casein is then weighed 
separately, burned, and the weight of the ash, consisting 
of mineral salts, is deducted from the weight first found. 
ESTIMATION OF CASEIN AND BUTTER. VARIOUS ANALYSES. 
207 
The amount of butter may be determined by evaporating 
the ethereal solution and weighing the residue, or by the 
difference between the total weight of casein and butter, 
and that of the casein after extraction by ether. The 
results published by Lehmann are quite satisfactory. 
§ 216. The mineral salts which are obtained as ash 
after the incineration of milk, may be submitted to quan- 
titative analysis. One litre of cow’s milk yielded to E. 
Marchand, 7.28 grammes of ash, and Filhol and Joly 
obtained 5.98 grammes of ash from one litre of woman’s 
milk; these ashes were constituted as follows:— 
Cow’s milk. 
Woman’s milk 
Potassium chloride, 0.994 
grammes. 
0.41 grammes. 
Sodium chloride, 0.458 
C i 
1.35 
Potassium phosphate, 0.063 
u 
f sodium phosphate 
( traces. 
Calcium phosphate, 3.458 
a 
3.95 grammes. 
Magnesium phosphate, 0.657 
u 
0.27 
Iron phosphate, 0.248 
u 
traces. 
Potassium sulphate, 0.703 
u 
Potassium silicate, 0.018 
u 
traces of CaFl2. 
Sodium carbonate, 0.671 
a 
traces. 
The following tables show the results of the analysis 
of cow’s milk by different observers and in different 
countries, the proportions given being calculated for one 
kilogramme of milk. 
POG- 
GI ALE. 
COM- 
M AII.LE, 
Marseilles 
Qce- 
VBNNE, 
Paris. 
Came- 
ron, 
Scotland. 
COM- 
MAII.LE, 
Algeria. 
Gorup- 
Besaxez, 
Holland. 
Water, 
8G2.80 
878.03 
872. 
870. 
853.85 
839.72 
Solid matter, 
137.20 
121.97 
128. 
130. 
146.15 
160.28 
Casein, 
38 
31.32 
35.70 
41. 
35.37 
34.87 
Albumen, 
19.08 
16.70 
7.32 
Butter, 
43.80 
30.10 
33.80 
40. 
43.54 
68.46 
Lactose, 
52.70 
35.34 
58.50 
42.80 
43.59 
43.50 
Mineral salts, 
2.70 
6.13 
6.20 
6.65 
6.14 
The following results are calculated for one litre of 
milk: — 208 
MILK. 
Marchand, 
Wanklyn, 
Wanklyn, 
Wanklyn, 
Norma Ddy. 
London. 
London. 
London. 
Country-fed 
City fed 
Alderney 
cow. 
COW. 
COW. 
Water . 
. 910.55 
900.9 
884.3 
898.8 
Solid matter 
. 121.35 
128.1 
144.7 
130.2 
Casein . . 
. 18.45 
41.6 
51.6 
47.5 
Albumen . 
. 5.37 
• • • • 
.... 
Butter . 
. 38.40 
31.6 
41.2 
33.i 
Lactose. 
. 51.85 
47.6 
44.3 
42.4 
Mineral salts 
. 7.28 
7.3 
7.6 
7.2 
Comparison of the milk of different animals, proportions in one kilogramme. 
Qcevenne. 
Comm a ills. 
Cameron. 
Cameron. 
Goat. 
Ewe. 
Mare. 
Sow. 
Water . 
. 878.40 
831.15 
903.10 
817.60 
Solid matter 121.60 
168.85 
96.90 
182.40 
Casein . 
. 27.60 
41.85 
19.55 
Albumen 
6.50 
19.09 
61.80 
Butter . 
. 30.20 
53.75 
10.55 
58.30 
Lactose 
. 57.30 
44.94 
62.83 
53.35 
Mineral salts .... 
9.22 
3.97 
8.95 
The following table shows the composition of 100 parts 
of woman’s milk, from the same woman under different 
conditions, as analyzed by Simon, and the general mean 
of many analyses by different observers. 
Density 
Solid 
matter. 
Casein. 
Butter. 
Lactose 
Mineral 
salts. 
1 mo. after confinement 
1.030 
11.62 
1.96 
3.14 
5.76 
0.166 
45 days “ “ 
1.030 
11.64 
2.2 
2.64 
5.2 
0.178 
3 mos. “ “ 
1.032 
13.4 
4.52 
2.74 
3.92 
0.287 
Sulfering from hunger 
1.034 
8.6 
3.55 
0.8 
3.95 
0.24 
General average 
1.0315 
12.3 
1.9 
4.5 
5.3 
0.18 
The following table shows at a glance the average 
composition of different milks, the proportions being cal- 
culated for 100 parts by weight. 
W ater. 
Solid 
matter. 
Casein. 
Butter. 
Lactose 
Salts. 
Woman’s milk 
87.7 
12.8 
1.9 
4.50 
5.3 
0.16 to 0.45 
Cow’s milk 
86.5 
13.5 
3.6 
4.05 
5.5 
0.30 to 0.90 
Ass’s “ 
90.7 
9.3 
1.7 
1.55 
5.8 
0.5 
Gloat’s “ 
87.6 
12.4 
3.7 
4.20 
4.0 
0.56 
Mare’s “ 
89 0 
11.0 
2.7 
2.50 
5.5 
0.5 
Ewe’s “ 
82.0 
18.0 
6.1 
5.33 
4.2 
0.7 DETECTION OF ADULTERATIONS. 
209 
Examination of Commercial Milk—Detection 
of Adulterations. 
§ 217. Among the frauds practised in the sale of milk 
are the following:— 
The sale of skimmed milk represented as unskimmed. 
The dilution of good milk with water or skimmed 
milk. 
The addition of sodium acid carbonate to prevent the 
coagulation of the milk. 
The addition of starch, flour, or chalk. 
The density of milk is often considered as a sufficient 
criterion of its purity, and if the average amount of 
cream be present, the criterion is a safe one. As has 
been mentioned, good unskimmed milk should have a 
density of about 1030; if it be diluted with water, this 
density will of course be lowered, but if the cream be 
removed, it will again be raised, so that a milk of normal 
specific gravity may be prepared by removing the cream 
from good milk, and then diluting it with water until the 
specific gravity is diminished to 1030. 
It is hence necessary to combine the indication afforded 
by the specific gravity with an estimation of the amount 
of butter present, as found by the lacto-butyrometer (§ 
215 5). 
After determining whether the milk has or has not 
been skimmed, the lacto-densimeter of Quevenne affords 
a means of approximately determining the amount of 
water that has been added to the milk, in case it has 
been diluted. 
The lacto-densimeter consists of an hydrometer, in 
which only the last two figures of the specific gravity, 
referred to water as 1000°, are given. 
On one side of the scale are marked the points to 
which the instrument should sink in pure unskimmed 
milk, and the approximate proportions of water which 
have been added, should it sink lower than in pure milk. 
Similar graduations on the other side of the scale refer 
to skimmed milk. 
An ordinary hydrometer may be employed instead of 
the lacto-densimeter, and the following table will indicate 210 
MILK. 
the proportion of water which has been added to the 
milk; only the last two figures of the specific gravity 
(water=1000) are given:— 
ater added. 
Specific gravity 
Specific gravity 
of pure milk. 
of skimmed milk. 
0 
. 33 to 29 
36.5 to 32.5 
i 
TO 
. 29 to 26 
32.5 to 29 
2 
TO 
. . 26 to 23 
29 
to 26 
3 
10 
. 23 to 20 
26 
to 23 
4 
TO 
. 20 to 17 
23 
to 19 
5 
TO 
. 17 to 14 
19 
to 16 
The lacto-densimeter is graduated at a temperature of 
15°, for which the above table is also arranged. If the 
temperature of the milk at the moment of observation 
be above or below that point, the degree found must be 
corrected by adding or subtracting the error indicated 
in the following table. 
Degree 
Pure milk. 
Skimmed milk. 
oflaeto- 
dec si- 
Temperature. 
Temperature. 
meter. 
5° 
10° 
20° 
25° 
5° 
O 
O 
rH 
20° 
25° 
15 
—0.9 
—0.6 
+0.8 
+ 1.8 
20 
1.1 
0.7 
0.9 
1.9 
—0.7 
—0.5 
+ 0.8 
+ 1.7 
22 
1.2 
0.7 
1. 
2.1 
0.7 
0.5 
0.8 
1.7 
24 
1.2 
0.7 
1. 
2.1 
0.9 
0.6 
0.8 
1.7 
26 
1.3 
0.8 
1.1 
2.2 
1. 
0.7 
0.8 
1.8 
28 
1.4 
0.9 
1.2 
2.4 
1. 
0.7 
0.9 
1.9 
30 
1.6 
1. 
1.2 
2.5 
1.1 
0.7 
0.9 
1.9 
32 
1.7 
1. 
1.3 
2.7 
1.1 
0.7 
1. 
2.1 
34 
1.9 
1.1 
1.3 
2.8 
1.2 
0.8 
1. 
2.2 
Thus, if the lacto-densimeter sink to 28 in a sample 
of skimmed milk under examination at 20°, the correct 
density of the milk, reduced to 15°, will he 1028.9. 
Sodium carbonate is sometimes added to milk for the 
purpose of preventing its coagulation by the formation 
of lactic acid. This adulteration is not easily detected, 
since normal milk contains traces of carbonates. About 
50 c.c. of the milk should be evaporated to dryness, the 
residue heated to redness, and then exhausted with w ater. 
The aqueous solution is evaporated to dryness, and the 
dry residue treated with a little hydrochloric acid. An DISEASED MILK. 
211 
abundant disengagement of carbon dioxide indicates 
that an abnormal proportion of a carbonate is present. 
According to Marchand’s analysis, 50 c. c. of normal 
cow’s milk contain about 38 milligrammes of sodium car- 
bonate ; the amount of carbon dioxide eliminated from 
the residue of the aqueous extraction of the ash of 50 
c. c. of the milk under examination, might, therefore, be 
compared with that disengaged from 33 milligrammes of 
sodium carbonate. 
Starch is detected by the aid of the microscope, and 
by the blue color it assumes when treated with iodine. 
The starch granules are larger than the milk globules, 
and are oval (Fig. 64). When examined by polarized 
Fig. 64. 
light, each granule appears marked with a dark cross. 
Before testing with iodine, the milk should first be boiled 
and allowed to cool; a few drops of tincture of iodine are 
then added, and, if starch be present, the liquid will as- 
sume a dark blue color. 
If milk be adulterated with chalk, the latter will be 
deposited on the bottom of a vessel in which the milk is 
allowed to stand, and may be recognized by its solubility 
with effervescence in hydrochloric acid; the solution so 
obtained responds to the usual tests for calcium salts. 
Starch granules. 
Diseased Milk. 
§ 218. Like other secretions, milk undergoes altera- 
tions in composition in diseased states of the system. 
The alteration may consist in an increased or diminished 
quantity of the normal constituents, or abnormal sub- 212 
MILK. 
stances may make their appearance. The more usual 
pathological elements found in milk, are urea, hemoglobin, 
blood, and pus. 
Urea is detected as described in section 166. 
The presence of hemoglobin, or of blood globules, is 
revealed by the altered color of the liquid, and by a 
microscopical examination. Figure 65 represents the 
difference between the appearance of blood globules and 
that of milk globules. 
Small quantities of pus may entirely escape detection, 
but a notable proportion, such as would be present in 
case of a large abscess in the mammary gland, may be 
Fig. 65. 
Fig. 66. 
detected by the aid of the microscope. Pus cells are 
larger than milk globules, and as the latter present 
neither nucleus nor cell wall, both of which are possessed 
by leucocytes, the distinction is not difficult when a suf- 
ficient number of pus cells are present (Fig. 66). 
Spots of a blue color sometimes make their appear- 
ance on the surface of milk. They appear to be occa- 
sioned by a species of fungus. 
Milk globules and blood cells. 
Milk globules and pus cells. 
Colostrum. 
§ 219. The liquid secreted by the mammary gland 
during the first few days after confinement does not pre- 
sent the characters of normal milk, and is called colos- 
trum. It is a viscous, yellowish liquid, having a specific 
gravity higher than that of milk, generally comprised be- 
tween 1040 and 1060. 
It contains less lactose than milk, and little or no COLOSTRUM. 
casein, the latter body being replaced by albumen. Con- 
sequently, when colostrum is boiled, it coagulates, the 
albumen becoming insoluble. As the secretion acauires 
the characters of normal 
milk, the albumen gradually 
disappears, and the propor- 
tion of casein correspond- 
ingly increases. 
In addition to the fat 
globules which are peculiar 
to milk, colostrum contains 
large granular corpuscles, 
having a yellowish color. 
Milk globules are nearly 
spherical, and highly refrac- 
tive ; their mean diameter 
varies from about to 
tAb °f a millimetre: it is uncertain whether they are 
surrounded by an albuminous envelop, or whether they 
are merely globules of fat held in suspension (Fig. 67). 
Colostrum globules appear to be agglomerated fat 
globules (Fig. 68). They vary in diameter from T TfffiJ 
Fig. 67. 
Milk globules. 
Fip. 68. 
Colostrum globules. 
to °f a millimetre. They are frequently found in 
normal woman’s milk, but not often in that of the cow 214 
SPERMATIC FLUID. 
and other animals. IIowrever, in certain diseases, cow’s 
milk bears a close resemblance to colostrum. 
The following is the result of the analysis by Simon 
of the colostrum secreted by a woman on the day of her 
delivery, together with the composition of the normal 
milk of the same individual. 
Colostrum. 
Milk. 
Water .... 
. 828.0 
887.6 
Solid constituents . 
. 172.0 
112.4 
Fat .... 
. 50.0 
25.3 
Albumen and casein 
. 40.0 
34.3 
Lactose .... 
. 70.0 
48.2 
Mineral salts . 
. 3.1 
2.3 
SPERMATIC FLUID. 
§ 220. The spermatic fluid consists of a mixture of 
the secretion of the testicles and Cowper’s glands, and of 
the mucus of the seminal vesicles. It has a character- 
istic odor, an alkaline reaction, and is colorless or only 
slightly grayish. It contains about fifteen per cent, of 
solid constituents, among which are a phosphorized fat, 
an albuminoid body, and certain mineral salts, notably the 
phosphates. The organized constituent of the spermatic 
secretion is peculiar, and characteristic, as will presently 
be described. 
The medico-legal expert is not unfrequently called 
upon to decide whether certain spots upon clothing or 
articles of furniture have been produced by the sper- 
matic fluid. In such a case, as Dragendorff justly re- 
marks, the chemical properties of the spermatic secretion 
are of little value, for the fluid may be mixed with vagi- 
nal mucus, leucorrhoeal or gonorrhoeal discharges, dried 
urine, and other matters, which would effectually dis- 
guise the chemical reactions of the seminal secretion, 
even were these latter much more characteristic than 
they actually are. 
Spots of dried spermatic fluid are evenly spread out, 
and usually have irregular, broken contours ; their color 
is grayish or yellowish, and they sometimes present a DETECTION OF STAINS. 
215 
shining appearance. When seen by transmitted light 
they appear translucid, and, unless the fabric be very 
thick, the spot penetrates the tissue and is visible on 
each side. Linen is stiffened by the dried secretion as 
if by starch, but the stiffness disappears when the spot 
is moistened with water; at the same time the charac- 
teristic odor of the seminal secretion is developed, and 
may be made more marked by boiling some water in a 
small test-tube and causing the vapor to pass through 
the spot. 
All of these characters are somewhat uncertain, and 
the only absolute proof of the presence of seminal fluid, 
must be derived from the detection of one or more sper- 
matozoids, by the aid of the microscope. 
The spermatic fluid is characterized by the presence 
of organized elements, known as spermatozoids, which 
may always be detected in the healthy secretion. A 
magnifying power of from 300 to 500 diameters is neces- 
sary for the definition of 
these small bodies; they 
are then seen to consist 
of an enlarged portion, 
called the head, and a 
long filamentary append- 
age, known as the tail 
(Fig. 69). The head has 
asomewhatflattenedpear 
shape, being 0.005 mm. 
long, 0.002 mm. thick, 
and 0.003 wide. The 
examination of supposed 
spots of seminal secre- 
tion, must then be con- 
ducted with a view to the 
detection of one or more spermatozoids. 
A strip about one centimetre in width is cut from the 
stained fabric, embracing the whole spot, if the latter be 
small, or taken from the centre if it be large ; in either 
case the extremities of the strip should extend beyond 
the borders of the spot. This strip is then suspended 
vertically, so that one end may dip into some distilled 
Fig. 69. 
Spermatozoids. 216 
SPERMATIC FLUID. 
water in a watch-glass. In the course of some time, 
varying from a few minutes to several hours, the water 
rises in the fabric, by capillarity, and the spot acquires 
all the external appearances of a fresh stain. 
When the stain has become thoroughly softened, the 
surface of the fabric is gently scraped with a clean knife, 
and the matter thus detached is placed on a microscope 
slide, and carefully spread out, by the aid of a drop of 
water, if necessary. It is then covered with a thin glass 
cover, and is ready for microscopic examination. 
The spermatozoids may be readily detected, either 
entire or broken, and in either case their identification 
is usually sufficiently easy. On the addition of a drop 
of acetic acid, the mucus is dissolved, and the form of 
the spermatozoids becomes more apparent. When broken, 
the fracture usually occurs close to the head, or in the 
middle of the tail. 
In addition to the spermatozoids, which are conclusive 
evidence of the nature of the stain, the microscopic ex- 
amination may reveal the presence of other bodies, de- 
rived either from the seminal secretion or from foreign 
sources. These are— 
Fat corpuscles. 
Granular and spherical mucous corpuscles. 
Small, irregular bodies derived from the seminal ves- 
icles. 
Epithelial cells from the urethra. 
Crystals of magnesium phosphate. 
Filaments of the fabric from which the spot was re- 
moved, and foreign matters with which it may have come 
in contact, as Avell as starch granules, in case the fabric 
were starched linen ; the starch granules, however, nearly 
always swollen and broken, sometimes unrecognizable 
with certainty. EXCREMENTS. 
217 
EXCREMENTS. 
§ 221. The solid excrements are highly complicated 
in composition, since, in addition to the intestinal mucus, 
which is constantly present, they contain a great variety 
of organized matter, derived from the food, from reme- 
dial agents, or from pathological action. 
A microscopic examination reveals the presence of 
epithelial cells, and the morphological constituents of the 
intestinal mucus, vegetable cells, starch granules, mus- 
cular fibres and fat globules, derived from the various 
aliments. In diseased conditions of the intestines, por- 
tions of intestinal mucous membrane, blood corpuscles, 
and filaments of fibrin may also be encountered. Infu- 
soria and crystals of ammonio-magnesium phosphate are 
frequently present, even in health. 
The solid excrements of a healthy adult contain about 
25 per cent, of solid matter, consisting principally of the 
debris of food which is insoluble, and insoluble salts. 
Among the principles which are soluble in water, alco- 
hol, or ether, are albuminoid bodies in small quantity, 
volatile fatty acids, lactic acid, products of the metamor- 
phoses of the biliary acids, salts of the fatty acids proper, 
cholesterin, occasionally glucose, and taurine and biliai'y 
pigments, together with certain mineral salts, principally 
earthy phosphates. The brown color of the faeces is at- 
tributable principally to hydrobilirubin. 
According to Hoppe-Seyler, the substance which Flint 
claimed to have extracted from the excrements, and to 
which he gave the name stercorin, was only impure 
cholesterin. 
Pathologically, the faeces may also contain albumen, 
urea, hematin, and large quantities of sodium chloride. 
Hematin may exist normally in the excrements, being 
derived from the food, but it may also be due to hemor- 
rhage into the intestinal canal. 
Analysis of the excrements will in nearly all cases be 
merely qualitative. The matters are triturated with alco- 
hol, and the alcoholic solution is separated by filtration; 218 
EXCREMENTS. 
the residue is exhausted with ether, the new residue 
treated with a little hydrochloric acid, and again ex- 
hausted with ether. The insoluble portion may then be 
extracted with water. The alcoholic solution will con- 
tain hydrobilirubin, fatty acids, either free or as alka- 
line salts, biliary acids, traces of cholesterin, and salts. 
The first ethereal extract will contain cholesterin and 
the fats which wTere undissolved by the alcohol, and the 
acid ethereal solution will contain calcium stearate and 
palmitate. If it be desired to estimate the proportion 
of mineral salts present, a knowrn weight of the matter 
should be incinerated, and the ash treated as in the 
usual course of mineral analysis. 
Albumen, which is present in the faeces in diarrhoea, 
may be detected by filtering the matter, after addition 
of a little water, if necessary, and boiling the filtrate 
with nitric acid. 
Urea is often eliminated in considerable quantity by 
the bowels in cases of cholera ; it may be separated by 
acidifying the filtered liquid with acetic acid, concentra- 
ting to a small bulk on a water-bath, and treating with 
nitric acid, as has been described for the preparation of 
urea from urine. 
The ingestion of iron compounds communicates a dark- 
green or black color to the excrements, in which the iron 
seems to be present in the form of sulphide. ANALYSIS OF ASHES. 
219 
EXAMINATION OF THE ASH OF ANIMAL 
SUBSTANCES. 
§ 222. In undertaking a qualitative analysis of the 
ashes obtained by incinerating animal substances, it must 
be borne in mind that the number of elementary bodies 
present in such substances is limited, and, as a rule, the 
analysis will therefore be confined to the detection of 
potassium, sodium, magnesium, calcium, iron, silica, sul- 
phur, chlorine, and phosphoric, carbonic, and sulphuric 
acids. Besides these elements, traces of manganese, 
copper, lead, and fluorine may sometimes be detected. 
The finely powdered ash should be boiled with dis- 
tilled water in a small flask or beaker, and the liquid 
should then be filtered. A few drops of the filtrate are 
evaporated upon a piece of platinum foil, and, if any 
residue remain, part of the ash has been dissolved by 
the water, and the aqueous solution must be tested as 
presently described. Should no residue remain, the ash 
is entirely insoluble in water, and the examination is con- 
tinued as in § 224. 
§ 223. The ash is partly soluble in water.—If the 
aqueous solution have an alkaline reaction, basic phos- 
phates, alkaline carbonates, or analogous substances are 
present; if, on the contrary, the liquid be neutral, only 
very small quantities of alkaline carbonates or phosphates 
can be present. 
a') A small portion of the solution is evaporated nearly 
to dryness, and a few drops of hydrochloric acid are 
added. If effervescence take place, and if the gas dis- 
engaged produce a cloud in a drop of lime-water placed 
on a watch-glass and held over the mixture, carbonic 
acid gas is present. If no effervescence take place, no 
carbonic acid is present. 
If the mixture smell of hydrogen sulphide, and a paper 
moistened with solution of lead acetate and held over the 
mixture be blackened, an alkaline sulphide is present ; 
such sulphide is usually produced by the reduction of 220 
ANALYSIS OF ASHES. 
alkaline sulphates during the incineration of the animal 
substance. 
b') To another portion of the solution, acidified with 
hydrochloric acid, or the same portion which has served 
for the preceding tests, a drop of barium chloride is 
added : the formation of a white precipitate, insoluble in 
hydrochloric acid and in nitric acid, indicates the pres- 
ence of an alkaline sulphate or of calcium sulphate. The 
aqueous solution used in making this test should not 
contain too much hydrochloric acid, for barium chloride 
is only slightly soluble in that acid, and might be thrown 
down, so leading to error. In this case, however, the 
barium chloride would redissolve on the addition of water. 
The absence of a precipitate after the addition of barium 
chloride, is a proof of the absence of soluble sulphates. 
(?) Another portion of the aqueous solution is acidu- 
lated with nitric acid, and treated with a few drops of 
silver nitrate. A white, curdy precipitate, insoluble in 
nitric acid, soluble in ammonia, and blackened by ex- 
posure to light, is due to the presence of a chloride; if 
no precipitate form, no chloride is present. 
d) A fourth portion of the solution is treated with 
ammonia, ammonium chloride, and magnesium sulphate. 
The presence of an alkaline phosphate would then occa- 
sion the formation of a white, crystalline precipitate of 
ammonio-magnesium phosphate, soluble in mineral acids 
and acetic acid. In dilute solutions, this precipitate only 
separates after standing, or when the liquid is stirred. 
e~) A small quantity of the liquid is evaporated nearly 
to dryness, and the residue is tested for sodium by the 
flame test; sodium salts impart a bright-yellow color to 
the colorless flame of alcohol or a Bunsen burner, into 
which they are introduced on the end of a platinum wire. 
/) The same concentrated liquid which was used for 
the detection of sodium is treated tvith a drop or two of 
hydrochloric acid, and a few drops of a strong solution 
of platinic chloride are added. If a light-yellow precipi- 
tate separate when the liquid is stirred, it is due to the 
formation of potassio-platinie chloride, and indicates the 
presence of potassium. In order that this test may 
succeed, the aqueous solution must be quite concentrated. QUALITATIVE ANALYSIS. 
221 
#) A few drops of the aqueous solution are tested 
with ammonium oxalate; the formation of a white, crys- 
talline precipitate shows the presence of calcium. 
§ 224. That portion of the ash which is insoluble in 
water is dissolved by boiling with hydrochloric acid. If 
an effervescence occur on first adding the hydrochloric 
acid, such disengagement of gas, which is without odor 
and produces a cloud in lime-water, indicates the presence 
of an earthy cai-bonate, probably calcium carbonate. As 
a rule, hydrochloric acid dissolves all of the ash, leaving 
a mere trace of silica, and perhaps unburned carbon; if, 
however, this residue have a reddish-brown color, due 
to the presence of ferric oxide, it should be boiled with 
a little concentrated hydrochloric acid containing a few 
drops of nitric acid. 
I. The solution is filtered, some solution of ammonium 
chloride is added, and the mixture is rendered strongly 
alkaline by ammonia, and heated to the boiling point. 
а) No precipitate is formed; in this case, iron, and 
calcium and magnesium phosphates, are not present. 
Proceed to II. 
б) A floeculent precipitate is formed; if this precipi- 
tate be reddish-brown, or brownish-yellow, iron is present, 
and the whole of the iron did not previously exist in 
combination with phosphoric acid. If, on the contrary, 
the precipitate be white or only slightly yellowish, all 
of the iron existed as phosphate. In this case, the 
precipitate is separated by filtration, and the liquid is 
examined according to II., while the precipitate is dis- 
solved in the smallest possible quantity of hydrochloric 
acid, and the solution obtained divided into several por- 
tions and tested as follows: — 
(1) One portion is treated with a solution of potas- 
sium ferrocyanide; a blue precipitate (Prussian blue) 
indicates the presence of iron. 
(2) To another portion is added a concentrated solu- 
tion of sodium acetate, and the mixture is shaken vio- 
lently ; a floeculent, white or yellowish precipitate indi- 
cates the presence of ferric phosphate; the absence of 
a precipitate shows that only traces of ferric phosphate, 
if any, can be present. 222 
ANALYSIS OF ASHES. 
(3) To the clear liquid, separated by filtration from 
the precipitate in (2), or without filtration should no 
precipitate have been formed, a solution of ammonium 
oxalate is added; a white,crystalline precipitate, soluble 
in hydrochloric acid, is occasioned by the formation of 
calcium oxalate, the calcium having probably existed as 
calcium phosphate or fluoride. 
(4) Another portion of the solution is treated with 
an excess of sodium acetate and enough ferric chloride 
to communicate a red color to the liquid, and the latter 
is boiled; by this means all of the ferric phosphate and 
ferric oxide are precipitated. The filtered liquid is freed 
from calcium by the addition of ammonium carbonate, 
and the new filtrate is treated with sodium phosphate; a 
white, crystalline precipitate, formed either immediately 
or after standing, indicates the presence of magnesium, 
which existed in the ash as magnesium phosphate. 
If no ferric phosphate has been detected in (2), the 
presence of phosphoric acid may be detected by the ad- 
dition of a drop of ferric chloride, which will occasion 
the formation of a yellowish precipitate. 
II. The solution in which no precipitate was formed 
by the treatment with ammonia and ammonium chloride, 
or the filtrate from the precipitate if any were formed, 
may contain magnesium and calcium which existed in the 
ash as carbonate. 
(1) This solution, which must contain ammonia and 
ammonium chloride, is treated with ammonium oxalate ; 
a white crystalline precipitate indicates the presence of 
calcium, originally existing as carbonate, at least not as 
either phosphate or fluoride. 
(2) The filtrate from the precipitated calcium oxalate 
or the liquid in which no precipitate has been formed, 
is treated with sodium phosphate ; the presence of mag- 
nesium will be indicated by the formation of a white 
crystalline precipitate, either immediately or in the course 
of twenty-four hours. QUANTITATIVE ANALYSIS. 
223 
Quantitative Analysis of Ashes. 
§ 225. A known weight of the ash is exhausted with dilute 
hydrochloric acid, and barium chloride is added to the fil- 
tered liquid as long as a precipitate continues to be formed; 
the precipitate is separated by filtration, and washed, the 
washings being added to the filtrate. The latter is then 
treated with ammonia and ammonium carbonate, and the 
new precipitate is also separated by filtration. If mag- 
nesium be present, this must be precipitated by ammonium 
phosphate. The clear liquid, thus freed from all metals, 
excepting potassium and sodium, is evaporated to dryness, 
and the residue is heated until all ammoniacal compounds 
are expelled. It is then dissolved in a little water, and 
should any insoluble residue remain, a new filtration will 
he necessary; the solution of potassium and sodium 
chlorides is evaporated to dryness, and the residue is 
calcined at a low temperature, and weighed. It is then 
redissolved in water, platinic chloride is added until the 
liquid has a dark-yellow color, and the mixture is allowed 
to stand twenty-four hours: the precipitate of platino- 
potassium chloride is then collected on a tared filter, 
washed with alcohol, and dried at a temperature between 
100 and 110°. The dry precipitate is then weighed in the 
filter ; 100 parts of platino-potassinm chloride correspond 
to 30.57 parts of potassium chloride. The weight of the 
potassium chloride so formed being deducted from that 
of the mixed chlorides, the remainder will represent the 
quantity of sodium chloride present. 
100 parts of potassium chloride contain 52.41 parts 
of potassium. 
100 parts of sodium chloride contain 39.32 parts of 
sodium. 
ESTIMATION OF POTASSIUM AND SODIUM. 
ESTIMATION OF PHOSPHATE OF IRON, CALCIUM, AND 
MAGNESIUM. 
One weighed portion of the ash serves for the estima- 
tion of phosphate of iron and also of calcium and mag- 224 
ANALYSIS OF ASHES. 
nesium. The filtered solution of the ash in hydrochloric 
acid is rendered alkaline by a slight excess of ammonia, 
and acetic acid is added. The earthy phosphates which 
were at first precipitated are thus redissolved, while the 
ferric phosphate remains unaffected, and may be collected 
on a filter, washed, dried, incinerated, and weighed. 
The calcium is precipitated from the filtrate by ammo- 
nium oxalate, and the calcium oxalate thrown down is 
collected, washed, dried, and incinerated. When cold, 
the residue is moistened with ammonium carbonate, and 
again heated to dull redness; the calcium carbonate so 
formed is then weighed. 100 parts of calcium carbonate 
contain 40 parts of calcium. 
The filtrate from the calcium oxalate is then concen- 
trated, and treated with an excess of ammonia, and a 
little sodium phosphate. After standing twenty-four 
hours, the precipitated ammonic-magnesium phosphate is 
collected on a filter, washed with dilute ammonia (1 part 
ammonia to 3 parts water), and dried. The dry precipi- 
tate should then be introduced into the crucible, and the 
filter burned separately, over a piece of glazed paper. 
The ash is added to the matter in the crucible, and the 
whole is ignited, first gently, finally at a white heat. 
The residue, consisting of magnesism pyrophosphate, is 
then weighed. 100 parts of magnesium pyrophosphate 
contain 21.62 parts of magnesium, and correspond to 
78.67 parts of normal magnesium phosphate, in which 
form the magnesium usually exists in the ash. 
ESTIMATION OF SULPHURIC ACID. 
Sulphuric acid is estimated in the form of barium sul- 
phate. The solution of a weighed quantity of the ash 
is treated with an excess of barium chloride, and the 
mixture is heated to boiling. The precipitated barium 
sulphate is then collected on a filter, and washed with 
hot water; part of the barium sulphate is apt to pass 
through the filter if cold water be employed. The pre- 
cipitate is then dried, calcined, and weighed. 100 parts 
of barium sulphate correspond to 42.06 parts of sulphuric 
acid, or to 41.20 parts of SO4. QUANTITATIVE ANALYSIS. 
225 
ESTIMATION OF CHLORINE. 
Chlorine may he estimated volumetrically, as described 
in § 154, or by the balance. In the latter case, one or 
two grammes of the ash are digested with about an equal 
quantity of pure sodium carbonate dissolved in distilled 
water; after standing some time, the mixture is evapo- 
rated to dryness, and the residue is exhausted with water, 
which dissolves the alkaline salts, while all of the earthy 
salts remain undissolved. The solution is acidulated 
with nitric acid, gently heated, and precipitated by add- 
ing silver nitrate. The silver chloride which is thrown 
down is collected on a filter, and washed with distilled 
water, until the washings show no turbidity on the addi- 
tion of hydrochloric acid. The precipitate is then dried 
in the filter, and when quite dry is turned out on glazed 
paper, and the filter is burned in a porcelain crucible. 
After cooling, since part of the silver chloride adhering 
to the filter-paper will have been reduced, a few drops 
of nitric acid and about as much hydrochloric acid are 
added, and the mass is evaporated to dryness on a water- 
bath. The precipitate which was left on the glazed paper 
is then added, and the whole is cautiously heated until it 
fuses. After cooling, the fused silver chloride is weighed, 
100 parts of it corresponding to 24.74 parts of chlorine. 
A weighed quantity of the ash is dissolved in hydro- 
chloric acid, and the filtered solution is treated with 
ammonia, ammonium chloride, and magnesium sulphate. 
After standing twenty-four hours, the precipitated am- 
monio-magnesium phosphate is collected, washed, dried, 
and incinerated, observing the precautions necessary in 
estimating magnesium. 100 parts of magnesium pyro- 
phosphate correspond to 63.39 parts of phosphoric anhy- 
dride, P205. 
Should it be necessary to estimate carbonic acid, the 
operations are conducted as described in § 200, b. 
ESTIMATION OF PHOSPHORIC ACII). PART III. 
ON THE DETECTION OF POISONS. 
§ 226. In cases of suspected poisoning not followed by 
death, the matters subjected to chemical analysis will be 
limited to the residue, if any, of the suspected substance, 
and to the urine and matters vomited by the patient. 
Should the poisoning terminate in death, the analysis 
should also include the stomach and its contents, the in- 
testines and their contents, the liver, bile, spleen, pan- 
creas, blood, and urine if the bladder be distended. In 
certain cases it may also be advisable to examine the 
brain, kidneys, and even the lungs. 
In any case, the materials should be immediately 
placed in clean glass jars, and labelled and sealed, until 
the chemical examination is to be undertaken. No dis- 
infectant or preservative of any kind should be employed, 
as such addition would preclude a research for the body 
used, and might prevent the detection of certain poisons. 
Each organ or substance to be examined should be 
analyzed separately, for all poisons are not equally ab- 
sorbed by the system, and, after absorption, all are not 
eliminated through the same channels; certain substances 
may be detected in the urine within a very short time 
after their ingestion, and the examination of that liquid 
may be of great importance and should not be neglected; 
this is especially the case in poisoning by antimony. 
Each organ should be finely divided separately, and 
the mass rendered as homogeneous as possible by tho- 
rough mixing. Since accidents are not impossible even 
in the most experienced and most careful hands, and 
since questions of accuracy may arise, only half of the 
suspected material should be submitted to chemical ex- 228 
DETECTION OF POISONS. 
animation, the other half! being resealed and reserved for 
unforeseen emergencies. 
It is of the utmost importance that the chemical re- 
agents and apparatus used in examinations for poisons 
should he absolutely pure and clean. All of the reagents 
employed must be tested in the same manner as in the 
examination for the poison, and must be changed or pro- 
pel ly purified should any trace of impurity be found. 
§ 227. As a rule, the chemist has received some indi- 
cations on the probable nature of the suspected poison 
before undertaking a toxicological investigation, these 
indications being furnished by the history of the case, 
certain post-mortem appearances if death have followed 
the poisoning, and the smell, taste, color, or other physi- 
cal property of the substance under examination. In 
such a case, the labor of the analyst is often compara- 
tively light; but in some cases no such aids are pre- 
sented, and it becomes necessary that a complete and 
systematic investigation shall be made, covering all or 
as many as possible of the poisonous substances which 
are known. The examination must then be so conducted 
that no part of the substance is wasted, and, for this pur- 
pose, volatile and easily destructible poisons, together 
with those of organic origin, are first sought, and the 
residues from this examination are examined for the pre- 
sence of mineral poisons, which would be unaffected by 
the previous operations. 
We will first consider the detection of the more common 
poisons individually, supposing that circumstances have 
pointed to one or the other of these as probably present; 
we will then summarily describe the method to be fol- 
lowed when the chemist has no idea of the particular 
poison present, and when a preliminary examination has 
given no affirmative result. ARSENIC. 
229 
ARSENIC. 
§ 228. Among the metals which it may he necessary 
to seek in chemico-legal examinations, arsenic is the most 
prominent. The well-known poisonous properties of its 
compounds, their want of smell, taste, and in many cases 
color, and their easy accessibility to the public, have 
combined to render this element one of the most frequent 
instruments of suicide and of criminal and accidental 
poisoning. 
§ 229. The more usual forms in which arsenic is met 
with are as follows :— 
Metallic arsenic, in the impure state often called 
cohalt, and used as a fly poison. This is insoluble in 
water, but slowly oxidizes in the air, and wThen kept 
under water becomes partially oxidized by the air dis- 
solved in the water, so that the commercial article always 
contains more or less arsenious oxide. 
Arsenious oxide, commonly known as white arsenic 
or rats’ bane. 
Arsenic disulphide, or realgar, a red solid, and 
Arsenic trisulpiiide, or orpiment, a yellow solid, 
used as pigments. 
Green pigments containing various compounds of 
arsenic and copper, among which are Scheele’s green 
(copper arsenite), and Schweinfurth's green (a com- 
pound of arsenite and acetate of copper). 
Potassium arsenite, used in medicine under the name 
Fowler’s solution. 
Although all of these substances, as indeed nearly all 
of the compounds of arsenic, are more or less poisonous, 
our attention will be particularly directed to arsenious 
oxide, since it is in this form that the poison is generally 
encountered in toxicological analysis. Again, the pro- 
cesses which serve for the detection of arsenious oxide 
are, when slightly modified, equally applicable to the 
detection of the other compounds. 
§ 230. The presence of arsenic trisulphide or of either 
of the arsenical pigments, is usually at once indicated by 230 
DETECTION OF POISONS. 
particles of colored powder, which sometimes tinge the 
entire mass. If yellow particles be found, they are 
carefully collected together, thoroughly dried, and mixed 
Avith a little poAvdered potassium cyanide ; the mixture, 
which must be quite dry, is introduced into a small tube 
of hard glass, closed at one end, and is heated to red- 
ness. If arsenic be present, a brilliant metallic mirror 
Avill be formed in the cooler part of the tube ; this is 
then examined as directed farther on (§ 233, a). Should 
no colored particles be found, but the presence of one of 
the arsenic pigments be still suspected, the substance is 
treated according to section 236. 
IDENTIFICATION OF ARSENIOUS OXIDE UNMIXED WITH 
OTHER SUBSTANCES. 
§ 231. Arsenious oxide commonly occurs as a white 
powder or in lumps. It is not very soluble in water; 
one part of the opaque, crystalline compound, as it usu- 
ally occurs in commerce, requires about seventy-five parts 
of water for its solution. Hence, when solid arsenious 
oxide has been administered, white grains of the undis- 
solved substance are frequently found in the contents of 
the stomach or in vomited mat- 
ter. The examination is then 
easy, and the first results 
should be decisive. 
§ 232. Some of the powder 
is cautiously heated in a 
small tube of hard glass, 
closed at one end, slightly 
warming the upper part of the 
tube before heating the sus- 
pected substance. Arsenious 
oxide will in this case sublime, 
forming a white or colorless 
crystalline sublimate, which, when examined by the aid 
of a microscope or good lens, will be seen to consist of 
brilliant octahedral crystals, and forms derived from an 
octahedra (Fig. 70). In order that the form of the 
crystals may be well marked, the tube must be heated 
Fig. 70. 
Crystals of arsenious oxide. ARSENIC. 
231 
slowly ; if this be neglected, it may be impossible to 
obtain any regular crystals. 
§ 238. A small quantity of arsenious oxide mixed 
with dry sodium carbonate and powdered charcoal, and 
heated in a small tube closed at one end, will be reduced, 
and a brilliant mirror of metallic arsenic will be formed 
in the cooler part of the tube. This experiment, known 
as the reduction test, is best performed as follows: a 
small tube of hard glass is drawn out to a long point, 
which is then sealed. The suspected powder is intro- 
duced into the point of the tube, and a small splinter of 
dry charcoal is placed in the drawn-out portion, about one 
centimetre above it. The part of the tube containing the 
charcoal is now heated to redness, and the tube is shifted 
so as to bring the end containing the powder into the 
flame. The arsenious oxide instantly volatilizes, and, 
passing over the incandescent charcoal, is reduced to 
metallic arsenic which condenses in a brilliant mirror 
farther on in the tube (Fig. 71). 
Fig. 71. 
a) The drawn-out end may then be cut off at a, the 
charcoal removed, and the tube again sealed. By care- 
fully moving the tube back and forwards in the flame, 
the arsenic may be again volatilized, and oxidized by the 
air in the tube into arsenious oxide, which condenses in 
octahedral crystals in the cooler part of the tube. If 
preferred, that part of the tube containing the mirror 232 
DETECTION OF POISONS. 
may be crushed, and the fragments heated in another 
tube. 
§ 234. The following tests, l<nown as the liquid tests, 
are applied to solutions suspected to contain arsenious 
oxide. A portion of the white powder is dissolved, by 
the aid of heat, in distilled water, and the tests are ap- 
plied to separate portions of the solution so obtained. 
a) Hydrogen sulphide passed through a solution of 
arsenious acid acidulated with a drop or two of hydro- 
chloric acid, occasions the formation of a bright yellow 
precipitate of arsenic trisulphide. This precipitate is 
readily soluble in ammonia. It may be further exam- 
ined by § 230. 
5) Ammonio nitrate of silver causes in solutions of 
arsenious acid, a canary-yellow precipitate of silver 
arsenite, soluble in nitric acid and in ammonia. The 
test is best made by first adding solution of silver nitrate, 
then a drop of dilute ammonia to the suspected liquid. 
In the presence of a chloride, this test is without value. 
c) When ammonio-sulphate of copper is added to a 
solution of arsenious acid, a pale green precipitate of 
copper arsenite is formed. 
In the course of a toxicological investigation, the crys- 
tals of arsenious oxide obtained by one of the preceding 
methods, or by one of those yet to be described, may be 
dissolved, by crushing the tube containing them and boil- 
ing the fragments with water, and the liquid tests applied 
to the solution so obtained. 
TIIE ARSENIC EXISTS IN AN ORGANIC MIXTURE. 
§ 235. If the mutters suspected to contain arsenic be 
liquid, they may be acidulated with hydrochloric acid, 
and at once submitted to Reinsch’s test or to Marsh’s 
test (see farther on). If they consist of both solid and 
liquid, the latter should be- separated as much as possible 
from the former, and the two portions examined sepa- 
rately. The liquid, if not too viscid, may be tested by 
lleinsch’s or Marsh’s test, and, if negative results be ob- 
tained after long and repeated trials, it may be assumed 
that no arsenic is present. If the presence of arsenic be ARSENIC. 
233 
indicated by these preliminary tests, the organic matter 
should be destroyed, and the examination continued as 
will presently be described. Solid or semi-solid sub- 
stances, such as the contents of the stomach or vomited 
matters, should be examined for small particles of arseni- 
ous oxide, which, if found, should be picked out, and 
identified as in §§ 231-234. 
The solid or semi-solid matter is then digested at a 
moderate temperature, on a water-bath, with dilute hy- 
drochloric acid (containing one-eighth or one-tenth acid); 
the solution obtained after filtration may be examined by 
Reinsch’s, Marsh’s, or Bloxam’s test. The solid residue 
is treated as directed in § 236. 
In medico-legal investigations as to the presence of 
arsenic, it is absolutely necessary, in case none of the 
poison can be detected in the stomach and its contents, 
to examine the various tissues of the body ; since the 
poison, when introduced into the stomach during life, 
is absorbed and gradually diffused throughout the whole 
system, and may be found in the blood, urine, muscles, 
and viscera, especially in the liver. It is therefore 
advisable to examine each of these for the poison, and 
it should never be concluded that because it cannot 
be detected in the stomach and its contents, none is to 
be found in other parts of the body. Should the indi- 
vidual, however, survive during several days after swal- 
lowing the poison, it is possible that the whole of it may 
be eliminated from the body, in which case, of course, 
no trace of it could afterwards be detected. 
If the solid matter to be examined have undergone 
putrefaction, the arsenious oxide may have become par- 
tially converted into arsenic trisulphide, which is some- 
times perceived in bright-yellow patches (see § 230). 
§ 236. The solid matter intended for examination is 
cut up as finely as possible with a knife or scissors, and 
heated in a porcelain or glass dish, on a water-bath, with 
about an equal weight of pure hydrochloric acid; pow- 
dered potassium chlorate is added from time to time, and 
the mixture stirred until the solid matter is entirely 
broken up, and the mass is fluid enough for filtration. 
Should the hydrochloric acid added be insufficient to DETECTION OF POISONS. 
render the mass fluid, distilled water may be added until 
a proper consistence is attained. After thus destroying 
the organic matter by hydrochloric acid and potassium 
chlorate, an almost clear solution is often obtained,— 
cellular tissue, fat, and ligneous fibres, alone resisting 
the action of the chlorine evolved. (Fresenius and Babo.) 
The excess of chlorine is expelled by evaporation on 
a water bath, or by passing a current of carbonic acid 
gas through the liquid. The bath is then filtered hot, 
distilled water being added before filtration, should the 
original volume of the liquid have been much reduced ; 
the matter on the filter is washed with distilled water, 
and the washings are added to the filtrate. 
The filtrate, which should not smell of chlorine, is in- 
troduced into a flask, and washed sulphurous acid gas 
is passed through it, until it smells strongly of the gas. 
Arsenic acid, into which any arsenic compound originally 
present would have been converted by the treatment 
with potassium chlorate, is thus reduced to arsenious 
acid. The solution is again heated on a water-bath until 
all of the sulphurous gas is expelled, and a portion of it 
may then be submitted to Marsh’s, Reinsch’s, or Blox- 
am’s test. 
§ 237. Hydrogen sulphide is passed through the liquid 
until the latter possesses a strong odor of the gas, even 
after standing some time, and the precipitated arsenic 
trisulphide is collected on a filter, and thoroughly washed 
with distilled Avater. It is then dried, and, with the filter, 
is spread out in a porcelain capsule, sprinkled with con- 
centrated nitric acid, and evaporated to dryness; the 
residue is again moistened with nitric acid and evapo- 
rated, and these operations are repeated until the residue 
acquires a yellowish color. It is then dissolved in a 
very little sodium hydrate solution, and well mixed with 
finely powdered sodium carbonate and a little sodium 
nitrate. The mixture is introduced into a porcelain cru- 
cible, and the capsule rinsed out with a little dry sodium 
carbonate, which is added to the matter in the crucible ; 
the contents of the latter are thoroughly dried, and 
gradually heated over a burner. The mass blackens, 
then becomes decolorized without deflagration, and melts ARSENIC. 
235 
to a colorless liquid. In case this liquid be not color- 
less, a little more sodium nitrate must be added. 
§ 238. The fused mass will contain sodium arsenate, 
together with nitrate, nitrite, sulphate, and carbonate of 
sodium. When cold, it is treated with the smallest pos- 
sible quantity of warm water, and a little sodium acid 
carbonate is added. Any antimony present would re- 
main undissolved as sodium antimonate, while tin would 
he precipitated as oxide by the sodium acid carbonate. 
The soluble portion, which contains sodium arsenate, 
should the original substance have contained arsenic, is 
separated from the insoluble residue, and the latter 
washed with distilled water, the washings being added 
to the filtrate. The residue may be used for the detec- 
tion of antimony and tin, if the presence of those metals 
be suspected. The filtrate is strongly acidulated with 
dilute sulphuric acid, care being taken that no loss occur 
by effervescence, and the liquid is evaporated in a por- 
celain capsule until all of the nitrous compounds are ex- 
pelled, as is indicated by the appearance of heavy vapors 
of sulphuric acid. 
The liquid remaining in the capsule is directly used 
for Marsh’s or Bloxam’s test; before the application of 
Reinsch’s test it should be boiled with some sulphurous 
acid solution ; but, as the metal is obtained directly by 
Marsh’s test, positive results yielded by that method, 
and confirmed by the crystalline sublimate and liquid 
tests, are sufficient evidence of the presence of arsenic. 
§ 239. Detection of cupro-arsenical pigments in paper 
hangings arid other fabides.—The cupro-arsenical pig- 
ments may be dissolved by soaking the suspected mate- 
rial in aqueous ammonia ; if copper be present, the so- 
lution will have a blue color, and arsenic may de detected 
by acidulating with hydrochloric acid, and boiling with 
copper foil, as directed in the following section. DETECTION OF POISONS. 
Reinsch’s Test. 
§ 240. Tliis test depends upon the fact that a solution 
of arsenious acid in hydrochloric acid deposits a gray 
coating on a copper slip or wire immersed in it; this 
coating is formed more or less quickly, according to the 
amount of arsenic present, and the temperature of the 
solution. Lippert has shown that it does not consist of 
pure arsenic, but is a compound containing five atoms of 
copper and two atoms of arsenic, As2Cu5. 
In the application of this test, which is one of the 
most delicate known for arsenic, the hydrochloric acid 
and copper used must be of absolute purity. To insure 
this, some of the hydrochloric acid is diluted with about 
four times its volume of water, and boiled for fifteen 
or twenty minutes with the slip of copper to be used. 
Should the copper then remain clean and bright, it may 
be assumed that both are pure. However, several small 
strips of the copper may be strongly heated in a small 
tube of hard glass in order to see that no crystals of 
arsenious oxide are deposited on the sides of the tube. 
The liquid to be tested should contain no sulphurous 
acid, and as the latter is frequently employed to reduce 
arsenic compounds to the arsenious condition, care must 
be taken that all of the gas is expelled from the liquid 
by boiling before applying lleinsch’s test. 
Although it is generally advisable to destroy all 
organic matter before proceeding to the detection of a 
mineral poison, good results may be obtained by directly 
submitting to lleinsch’s test the liquid produced by 
digesting -the suspected matters with hydrochloric acid 
diluted with about five times its volume of water. 
In order to apply this test, acidify a portion of the 
solution suspected to contain arsenic with a little hydro- 
chloric acid; heat to boiling, and, as soon as the liquid 
begins to boil, introduce one or more small strips of 
bright copper foil that has been found free from arsenic. 
If arsenic be present, it will form a steel-colored coating 
on the copper, and may be identified in the following 
manner:— marsh’s test. 
237 
a) Carefully wash the copper strips, boil them with a 
little alcohol should any fatty matter have been present 
in the suspected liquid, and dry them by pressure be- 
tween folds of filter-paper, or by a gentle heat. Then 
introduce them into a small tube of hard glass, closed at 
one end, and heat, first gently, then strongly, so that the 
arsenic may volatilize, and, coming in contact with the 
air in the tube, may be oxidized to arsenious oxide, which 
will condense in octahedral crystals on the sides of the 
tube. The crystals are identified under the microscope. 
b) Remove the copper from the tube, and crush that 
portion of the latter containing the sublimate, taking 
care that the crystals be not detached. Boil the frag- 
ments with as small a quantity of distilled water as 
possible, and examine the solution so obtained by the 
liquid tests (§ 234 a and £). Or, unless the tube be 
very narrow, the closed end may be cut off, and the 
whole tube boiled with water in a test-tube, the test 
being applied as before. 
The difference between the deposit obtained from 
arsenic by Reinsch’s test and that produced by antimony, 
will be considered when treating of the latter metal. 
Should arsenic be present in the form of arsenic acid, 
this must be reduced by sulphurous acid, and the excess 
of the latter entirely expelled, before applying Reinsch’s 
test. 
Marsh’s Test. 
§ 241. When a solution of arsenious oxide, an arse- 
nite, or an arsenate, is submitted to the action of nascent 
hydrogen, the arsenic compound is reduced, and the arse- 
nic combines with the hydrogen, forming hydrogen arse- 
nide, a poisonous gas which must be handled with care.. 
This reaction is applied to the detection of arsenic by 
Marsh’s apparatus, as it has been modified by Berzelius. 
Various sources of nascent hydrogen have been proposed; 
potassium hydrate and aluminium,1 sodium amalgam and 
water,2 have been employed by different chemists, but 
the method originally employed by Marsh, the action of 
1 Gatehouse, 1873. 
* Naquet, 1873. 238 
DETECTION OF POISONS. 
zinc upon dilute sulphuric acid, is by far the most con- 
venient for practical purposes, and, when proper care is 
taken to insure the purity of the reagents, is open to no 
well-founded objection. 
A gas bottle (Fig. 72) is arranged for the preparation 
of hydrogen, the delivery-tube KE being of hard glass, 
Fig. 72. 
and so connected with the bent tube D that the jet may 
be turned either up or down. The wider tube D may 
contain some cotton-wool destined to dry the gas. 
Some pure zinc is placed in the bottle, and when all is 
in readiness cold dilute sulphuric acid, containing about 
one-sixth acid, is introduced through the funnel-tube. 
After sufficient time has been allowed for the expulsion 
of the air from the bottle, the gas is lighted at the jet, 
and a piece of clean porcelain depressed into the flame. 
If, after repeated trials, no spots or stains are formed 
on the porcelain, it may be assumed that both zinc and 
acid are pure, and some of the suspected liquid is intro- 
duced by the funnel-tube. The gas should not be ex- 
tinguished while pouring in the liquid, but care should 
be taken that no bubbles of air enter. If frothing occur 
after the introduction of the suspected liquid, it may be 
checked by pouring in a little alcohol. Should any 
quantity of arsenic be present, the appearance of the 
flame undergoes a striking change ; from almost colorless, 
it becomes pale-blue, and emits fumes of arsenious oxide. 
Whether the appearance of the flame be changed or 
not, a piece of clean porcelain (a crucible lid or piece 
of a broken capsule answers well) is depressed into the marsh’s test. 
239 
flame, and, should the liquid have contained arsenic, dark 
spots will be deposited on the porcelain. As many of 
these deposits as possible are obtained, and are subjected 
to the following tests in order to ascertain whether they 
be really arsenic or be due to antimony, which would 
produce very similar results. 
a) The arsenic spots will volatilize when gently heated 
over a lamp, and garlicky odors of arsenic will be per- 
ceptible. Antimony spots are not easily volatilized. 
b) Arsenic spots are but slowly dissolved by yellow 
ammonium sulphydrate ; antimony spots are dissolved 
immediately. 
<?) Arsenic spots are at once dissolved by solutions of 
the hypochlorites (sodium hypochlorite, chlorinated 
lime); antimony spots are affected very slowly by the 
same reagents. 
d) If the spot be moistened with a drop of strong 
nitric acid, and then carefully heated until the excess of 
acid is expelled, a white residue will be obtained should 
the spot consist of either arsenic or antimony. This is 
touched with a drop of silver nitrate solution, and a drop 
of ammonia on the end of a glass rod is held near the 
spot: if the latter be arsenic, a brownish-red color is 
produced, either before or after the application of the 
ammonia, due to the formation of silver arsenate. Anti- 
mony spots give no color when treated in this manner, 
but in order that the reaction may succeed with arsenic, 
care is necessary in applying the reagents. 
e) While the gas is being disengaged, and burning at 
the jet, heat the hard glass delivery-tube at the point K. 
If arsenic be present, a metallic mirror or ring will be 
formed a little farther on in the tube, and, should this 
ring consist of arsenic, it may be readily driven up and 
down the tube by moving the lamp. At the conclusion 
of the experiment the portion of the tube containing the 
mirror is cut off, broken up, and carefully heated in a 
small tube closed at one end : after identifying the sub- 
limate of arsenious oxide so obtained, it is examined as 
directed in section 240 b. 
The gas is extinguished at the jet, the latter is turned 
down, and the escaping gas made to pass through a solu- 240 
DETECTION OF POISONS. 
tion of silver nitrate. Should arsenic be present, the 
silver nitrate is reduced, and metallic silver is deposited 
as a brownish or black precipitate, while arsenious acid 
is formed and remains in solution, together with the excess 
of silver nitrate if an excess have been employed. The 
solution is filtered from the precipitated silver, a few 
drops of silver nitrate are added to the clear filtrate, and 
very dilute ammonia is added, drop by drop, by the aid 
of a glass rod. A canary-yellow precipitate of silver 
arsenite at once indicates the presence of arsenious acid. 
Under these circumstances, hydrogen antimonide also 
causes the formation of a brown or black precipitate in 
solutions of silver nitrate, but this precipitate consists of 
a compound of antimony and silver, and the addition of 
silver nitrate and ammonia after filtration, yields no re- 
sults. 
When only a small quantity of a substance is to be 
tested for arsenic, the apparatus represented in Figure 
73, and in which the flask is replaced by a tolerably large 
Fig. 73. 
test-tube, may be employed. The delivery-tube is con- 
tracted at several points, and its end drawn out so as to 
form a very narrow tube about five centimetres long. 
The wider parts of the contracted portions are heated by 
a spirit lamp or Bunsen burner, and, in order to insure 
the recovery of all of the arsenic, the heat is applied 
before the suspected substance is introduced. As many 
rings or mirrors are obtained as possible, and these are ELECTROLYTIC TEST. 
241 
tested as in § 233, a. When the quantity of substance 
for analysis is very small, no attempt should be made to 
obtain spots on porcelain, as some of the arsenic is then 
always volatilized and lost. 
The flask or test-tube may be immersed in cold water, 
and if the disengagement of gas be very slow, drying 
may be unnecessary. 
Electrolytic Test. 
§ 242. This exceedingly delicate test has been im- 
proved and modified by Bloxam, by whose name it is now 
generally known. It depends upon the fact that when a 
tolerably strong electric current is made to traverse a 
Fig. 74. 
solution containing arsenic, hydrogen arsenide is evolved 
at the negative pole, together with the hydrogen of the 
decomposed water. 
The apparatus devised by Bloxam consists of a tubu- 
lated bell-jar of 50 or 100 cubic centimetres capacity, 
the bottom of which is closed by a piece of parchment 
paper tightly bound over the edges. To the tubu- 
lure of the bell-jar is adapted a cork pierced with two 
holes, through one of which passes a funnel-tube which 242 
DETECTION OF POISONS. 
nearly touches the paper bottom, while the other gives 
passage to a delivery-tube bent at a right angle (Fig. 
74). A strip of platinum foil cut in the shape of a 
spade is secured between the cork and the neck of the 
jar, so that its broad end, which is in the bottle, almost 
touches the diaphragm, while the other end projects 
several centimetres beyond the tubulure. The small 
hell-jar is then placed in a cylindrical jar, not much wider 
than itself, and not so flat at the bottom as to close the 
hell-jar. Between the exterior and interior vessels is 
suspended a second strip of platinum, similar to the first, 
and nearly touching the bottom of the jar. By means 
of a caoutchouc joint, the bent delivery-tube is connected 
with a narrow tube of infusible glass, drawn out to a fine 
point about five centimetres long. This tube must be 
properly supported, so that it may be heated at the point 
at which its diameter begins to contract. 
The apparatus is charged with sulphuric acid diluted 
Avith three times its weight of water, both the external 
and internal vessels being about one-quarter filled. The 
whole is then placed in a basin of water to prevent too 
great a rise in temperature, and the platinum strip in 
the bell-jar is connected Avith the zinc or negative pole 
of a voltaic battery, Avhile that suspended in the cylin- 
drical jar is connected with the positive pole. Ten or 
fifteen minutes haAung been alloAved for the expulsion of 
the air in the bottle by the hydrogen evolved, the shoul- 
der of the drawn-out tube is heated to dull redness, and 
maintained at that temperature for ten or fifteen-minutes ; 
should no ring of arsenic or of arsenic trisulphide be 
then visible in the narroAV part of the tube, the sulphuric 
acid is pure, and the solution to be tested for arsenic is 
sloAvly poured doAvn the funnel-tube, care being taken 
to avoid the introduction of air bubbles. Should froth- 
ing occur, it may be checked by the introduction of a 
few cubic centimetres of alcohol. If no deposit of arse- 
nic or its sulphide be formed within ten minutes, 2 c. c. 
of a solution of sulphurous acid or hydrogen sulphide 
are poured in by the funnel-tube, and the experiment is 
continued for another quarter or half hour. Should 
arsenic be present, a metallic ring of arsenic, or a greenish- QUANTITATIVE ESTIMATION OF ARSENIC. 
243 
yellow, iridescent ring of arsenic trisulphide, will be 
deposited in the narrow part of the tube. Should no odor 
of hydrogen sulphide he perceptible at the end of the tube 
at the termination of the experiment, a little more sul- 
phurous acid or hydrogen sulphide should he added. 
The lamp is now removed, and the tube allowed to 
cool, after which the part containing the deposit is cut olf, 
and gently warmed, in a small test-tube, with a solution 
of ammonium carbonate, which slowly dissolves the yellow 
sulphide. The tube with the metallic portion of the 
deposit is washed with distilled water, dried, and treated 
according to section 241 e. 
The whole of the arsenic is seldom removed from the 
liquid by electrolysis. The remainder may be extracted 
by saturating with hydrogen sulphide, and gently heat- 
ing in a covered vessel for several hours. The precipi- 
tated arsenic trisulphide, mixed with organic matter, is 
collected on a filter, washed, and treated as directed in 
section 237. 
Quantitative Estimation of Arsenic. 
§ 243. It is often a matter of importance to determine 
the absolute quantity of arsenic present in a mixture or 
in an organ, such as the liver. The operation is con- 
ducted precisely as indicated in §§ 236-238, except that 
the solution of sodium arsenate is not treated with sul- 
phuric acid, hut with ammonium chloride, ammonia, and 
magnesium sulphate, and the mixture is allowed to stand 
twenty-four hours. The arsenic will then be completely 
precipitated as ammonio-magnesium arsenate ; this is 
collected on a tared filter, washed with dilute ammonia, 
dried at 100°, and weighed. Ammonio-magnesium arse- 
nate contains MgNH4As04-f |H20; consequently 100 
parts of the precipitate represent 39.47 parts of arsenic, 
or 52.1 parts of arsenious oxide. 244 
DETECTION OF POISONS. 
ANTIMONY. 
§ 244. The only form in which antimony is commonly 
met with, is the double tartrate of antimony and potas- 
sium, generally known as tartar-emetic or tartarized 
antimony. It enters into a number of medicinal prepara- 
tions, and has not unfrequently been used as a poison. 
It contains K(SbO)C4II406. 
•In the crystalline state, tartar-emetic occurs in rhombic 
octahedra, which contain one molecule of water of crys- 
tallization, and effloresce in dry air. It is soluble in 
about fifteen parts of cold water, and in about two parts 
of boiling Avater, insoluble in alcohol. 
When in the pure state, tartar emetic may be recog- 
nized by the following properties: — 
a) Hydrogen sulphide produces an orange-colored 
precipitate of antimony trisulphide. This precipitate is 
insoluble in ammonia, but dissolves in ammonium sul- 
phide. 
b~) With hydrochloric acid, solutions of tartar emetic 
give a Avhite precipitate of antimony trioxide, soluble in 
an excess of acid, but re precipitated on the addition of 
water. 
c) When a feAV drops of a solution of antimony acidu- 
lated with hydrochloric acid are poured upon platinum 
foil, and a piece of zinc is placed in the liquid, a black 
deposit of antimony is formed on the foil. This deposit 
is insoluble in hydrochloric acid ; if it be moistened Avitli 
yelloAv ammonium sulphide, and the solution be evapo- 
rated to dryness, an orange-colored residue of antimony 
sulphide will remain. This should be compared Avith 
the residue left upon the foil by ammonium sulphide 
alone. 
§ 245. In the presence of organic matter, antimony 
is detected by processes similar to those folloAved in 
the case of arsenic. The organic matter is destroyed 
in the same manner, and the solution obtained may be 
directly submitted to Marsh’s or to Reinsch’s test. The ANTIMONY. 
245 
differences of the results obtained from those yielded by 
arsenic are as follows: — 
а) When an antimonial solution is boiled with copper 
and hydrochloric acid, a bluish-black or purple deposit 
of antimony is formed on the copper. When the latter 
is washed, dried, and heated in a tube, it rarely gives a 
crystalline sublimate winch can be mistaken for arseni- 
ous oxide ; but on strongly heating, a white sublimate is 
formed, and though this is generally amorphous, it must 
be borne in mind that arsenious oxide and antimonious 
oxide are isodimorphous, and it occasionally happens 
that the antimonial sublimate presents, under the micro- 
scope, such a crystalline appearance as might lead to an 
inference of the presence of arsenic. However, this 
deposit is insoluble in water, and when it is boiled with 
water in a test-tube and ammonio-nitrate of silver is added 
to the liquid, no canary-yellow' precipitate is formed. 
When the copper coated with the antimonial deposit 
is boiled with a very dilute solution of potassium hydrate, 
slightly colored with potassium permanganate solution, 
potassium antimonate is formed ; the solution may then 
be filtered from deposited manganese oxide, and treated 
with hydrogen sulphide and hydrochloric acid. An 
orange-colored precipitate of antimony sulphide will be 
formed. This test is quite delicate, and is trustworthy, 
thus furnishing a ready method for the identification 
of antimony. 
б) With Marsh’s test, antimony yields stains on por- 
celain, and metallic rings analogous to those produced 
by arsenic, from which, howrever, they may be readily 
distinguished. 
1. The antimony spots and rings are much less vola- 
tile than those of arsenic, and the rings are deposited 
nearer the heated portion of the tube. They are not 
readily driven up and down by moving the source of 
heat. 
2. Antimony spots are not easily dissolved by solu- 
tions of sodium hypochlorite or chlorinated lime. Ar- 
senic spots are at once dissolved by these reagents. 
3. Antimony spots dissolve readily in yellow ammo- 
nium sulphide, and the solution, when evaporated, leaves 246 
DETECTION OF POISONS. 
an orange-colored residue of antimony sulphide ; arsenic 
spots are not easily dissolved by ammonium sulphide. 
4. Antimony spots, when oxidized by nitric acid and 
evaporated to dryness, leave a residue which does not 
produce a brownish-red color with ammonio-nitrate of 
silver, as do spots of arsenic. 
In Bloxam’s test by the electrolytic method, hydrogen 
antimonide is evolved much less readily than hydrogen 
arsenide, the greater part of the antimony being depos- 
ited as a black coating on the platinum plate connected 
with the negative pole of the battery. If the plate be 
washed, and gently heated with a little yellow ammo- 
nium sulphide, the antimony dissolves, and an orange- 
colored residue of antimony sulphide is left after the 
evaporation of the solution. 
Separation of Antimony from Arsenic. 
§ 246. Should both antimony and arsenic be present 
in an organic mixture, the precipitate formed by passing 
hydrogen sulphide through the liquid obtained after the 
destruction of organic matter, as indicated in § 286, will 
contain both metals in the form of sulphides. If this 
precipitate be thoroughly washed with distilled water, 
until all traces of hydrogen sulphide are removed, the 
arsenic sulphide may be dissolved by pouring ammonia 
on the precipitate in the filter, and will pass through, 
while the insoluble antimony sulphide will remain. The 
latter may then be washed, dissolved by boiling with 
hydrochloric acid, and examined by Marsh’s test if de- 
sired. If much sulphur be present with the precipitated 
sulphides, or if the hydrogen sulphide be not entirely 
removed by washing, part of the antimony sulphide will 
be dissolved by the ammonia, and the separation will 
consequently be more or less imperfect. 
If arsenic and antimony be present together, the whole 
of the latter will remain as insoluble sodium antimonate 
when the mixed sulphides are heated with a mixture of 
sodium carbonate and sodium nitrate, as directed in § 238, 
while the sodium arsenate formed at the same time is dis- 
solved when the fused mass is treated with water. The 247 
TIN . 
insoluble antimonic salt is collected on a filter, washed, 
dried, and fused with five or six times its weight of po- 
tassium cyanide in a small porcelain crucible. Metallic 
antimony is then formed, and collects in a button at the 
bottom of the crucible. The cold mass is, therefore, 
treated with water, and the button removed : if a quanti- 
tative estimation is desired, this button is weighed be- 
fore proceeding to its identification by chemical tests. 
100 parts of antimony correspond to 266 parts of dry 
tartar-emetic. 
TIN. 
§ 247. Although tin and its compounds are neither 
common nor dangerous poisons, for several reasons the 
analyst must be familiar with their more important reac- 
tions. Stannous chloride, SnCl2, is largely used in 
dyeing, and has been employed criminally as a poison; 
and certain reactions of arsenic and antimony resemble 
those of tin to such an extent that it is of importance to 
be able to distinguish between these metals. 
Tin is separated from organic mixtures exactly as the 
two metals previously considered. After the destruction 
of organic matter by potassium chlorate and hydrochloric 
acid, tin will remain in the liquid in the form of stannic 
chloride. When hydrogen sulphide is passed through 
the solution, pale-yellow stannic sulphide is precipitated, 
and might easily be mistaken for arsenic trisulphide ; 
but, like antimony sulphide, this precipitate is insoluble 
in ammonia, and may be separated from any arsenic that 
might be present at the same time, by thorough washing 
with distilled water and subsequent treatment with am- 
monia. 
The precipitate of stannic sulphide is but partially 
reduced by potassium cyanide, and if the mixture be 
heated in a glass tube, no metallic ring or mirror is 
formed. 
When stannic sulphide is fused with potassium nitrate, 
it is converted into soluble potassium stannate, but with 248 
DETECTION OF POISONS. 
sodium nitrate it yields sodium stannate, which is insolu- 
ble, especially in hot water. When these stannates are 
dissolved in sulphuric acid, and introduced into Marsh’s 
apparatus, no spots or rings are obtained, but metallic 
tin remains in the gas bottle after the zinc is all dissolved. 
As tin is not entirely insoluble in dilute sulphuric acid, 
the residue in the gas-bottle should be filtered before all 
of the zinc has disappeared ; the particles of tin are 
then collected, and any that adhere to the zinc are re- 
moved by washing. They are then dissolved in a little 
warm hydrochloric acid, and the presence of tin may be 
detected in the solution. 
In addition to the hydrogen sulphide test before men- 
tioned, if some of the solution of stannous chloride be 
poured into a solution of mercuric chloride, a white pre- 
cipitate of mercurous chloride is formed, which changes 
to gray, if enough tin be present, owing to the separa- 
tion of finely divided metallic mercury. 
MERCURY. 
§ 248. After arsenic, mercury is the mineral poison 
most frequently met with in toxicological investigations. 
The compounds of which it forms part, and in which it 
may be either accidentally or criminally administered with 
poisonous effects, are numerous ; metallic mercury and 
its amalgams are employed in the arts ; its chlorides and 
oxides are used in medicine, as are also its iodides and 
other salts of less importance. Of all these compounds, 
mercuric chloride, or, as it is commonly called, corrosive 
sublimate, is that by which life has been most often de- 
stroyed or endangered. 
When pure, mercuric chloride is a white, crystalline 
solid, which is soluble in about nineteen parts of cold 
Avater, and also soluble in alcohol and ether. It is de- 
posited from its hot, saturated, aqueous solution, in right- 
rhombic, anhydrous prisms. Its solutions respond to the 
tests indicated further on. MERCURY. 
249 
SEPARATION FROM ORGANIC MIXTURES. 
§ 249. When the presence of mercury is suspected in 
organic mixtures, such as vomited matter, or the contents 
of the stomach, if the solid and liquid portions of the 
matter can be readily separated from each other, a de- 
cisive preliminary test may be made on the liquid ; or 
the whole mass may be at once treated as indicated in 
section 254. 
§ 250. If the liquid is to be treated separately, it is 
acidulated with hydrochloric acid, and boiled for quarter 
or half an hour with one or more pieces of clean, bright 
copper foil or wire. If mercury be present in the solu- 
tion, it will be separated, and deposited as a gray film 
on the surface of the copper. The latter is then re- 
moved from the liquid, washed with a little alcohol and 
dilute ammonia to remove fatty matters and any adhering 
acid or salt of copper, and carefully dried by pressure 
between folds of filter-paper; it is then distributed in 
several small, hard-glass tubes, closed at one end. The 
end of the tube containing some of this coated copper 
being heated in a lamp-flame, the mercury volatilizes and 
condenses in the cooler part of the tube, forming a gray- 
ish ring in which globules of mercury may often be seen 
by the naked eye,—nearly always by the aid of a good 
lens. 
§ 251. If, however, only a trace of mercury be pre- 
sent, the globules may not be distinguishable. In this 
case the copper is shaken out of the tube, and a very 
small particle of iodine is introduced, and vaporized by 
the application of a gentle heat. The iodine vapor com- 
bines with the mercury, and the gray ring is in this 
manner converted into mercuric iodide, which is yellow 
Avhile hot, but changes to red on cooling ; the change in 
color is sometimes quite slow, but may be brought about 
instantly by touching the yellow deposit with a hard 
body, such as a glass rod or a copper wire. 
§ 252. The mercurial ring in another tube, from which 
the copper has been removed, is dissolved in nitro-hy- 
drochloric acid. A solution of mercuric chloride is 
thus obtained. This solution is evaporated to dryness, 250 
DETECTION OF POISONS. 
and the residue is dissolved in a little water; the follow- 
ing tests are then applied : — 
a) A drop of stannous chloride added to part of this 
solution will produce a white precipitate of mercurous 
chloride, which changes to gray on the addition of more 
stannous chloride. 
b~) Hydrogen sulphide gives a precipitate which is at 
first white, but changes to yellowish and black, if the 
reagent be not employed in very small quantity. Am- 
monium sulphide acts in the same manner in mercurial 
solutions. 
c) Ammonia produces a white precipitate of rnercur- 
ammonium chloride. 
§ 253. The dry residues of mercuric chloride obtained 
from other tubes in the same manner, may be tested in 
white porcelain dishes by the following reagents. 
a) A drop of potassium iodide solution produces a red 
color, due to the formation of mercuric iodide; the color 
disappears in an excess of the reagent, in which mercuric 
iodide is soluble. 
5) Potassium hydrate gives a yellow, or orange- 
colored spot of mercuric oxide, Avhich is dissolved with 
difficulty by a large excess of the reagent. 
DESTRUCTION OF THE ORGANIC MATTER. 
§ 254. In whatever form, excepting cinnabar, mercury 
may have been present in the original mixture, it is 
always obtained in solution as mercuric chloride by the 
process about to be described. Cinnabar is not poisonous, 
and is, therefore, not likely to be encountered in a toxi- 
cological investigation; but were it present, a sufficient 
quantity of it would be dissolved to indicate the presence 
of mercury, though the larger portion of it would re- 
main unaffected. 
As all mercurial compounds are volatile, the organic 
matter present may not be destroyed by any process 
which depends upon the application of a high degree of 
heat, such as deflagration with potassium nitrate. 
The most satisfactory and best method consists in the 
use of hydrochloric acid and potassium chlorate, pre- MERCURY. 
251 
cisely as has been indicated in the case of arsenic (§ 236). 
After all of the organic matter has disappeared, and the 
liquid is fit for filtration, it is heated to expel the excess 
of chlorine, and filtered hot. The filtrate is then satu- 
rated with hydrogen sulphide, and the black precipitate 
formed is collected on a filter, and thoroughly washed 
with distilled water. It is insoluble in either hydro- 
chloric or nitric acid separately, but dissolves readily in 
a mixture of the two. It is, therefore, at once dissolved 
in nitro-hydrochloric- acid, the solution is evaporated to 
dryness, and the residue is dissolved in a small quantity 
of water, acidulated with a few drops of hydrochloric 
acid to facilitate the solution of any mercuric sulphate 
which might have been formed. 
When introduced into Marsh’s apparatus, this solution 
does not affect the character of the gas evolved, and no 
spots or rings can be obtained. The solution is sub- 
jected to the tests given in sections 250-253. 
Should sufficient of the dry residue from the evapora- 
tion of the solution in nitro-hydrochloric acid be available, 
a portion of it may be mixed with some dry sodium car- 
bonate, and the mixture strongly heated in a small 
reduction tube. The mercuric salt will thus be reduced, 
and metallic mercury will volatilize and condense on the 
sides of the tube. The mercury rings may be tested 
according to section 251. 
In addition to the characters of these rings that have 
already been mentioned, they differ from arsenical and 
antimonial rings in the following particulars :—■ 
The mercurial rings sublime without odor. 
They are not oxidized by heating in the presence of 
air. 
They are not dissolved by an alkaline solution of 
sodium hypochlorite. 
Ammonium sulphide converts them into black, mercuric 
sulphide. 
§ 255. Should the presence of mere traces of mercury 
he suspected, it is not advisable to precipitate by hydro- 
ELECTROLYTIC TEST. 252 
DETECTION OF POISONS. 
gen sulphide the solution obtained after destroying the 
organic matter by potassium chlorate. In such a case, 
the best course is to directly submit the filtered liquid 
to electrolysis, a battery of about five Smee cells being 
employed. The positive pole should consist of a small 
platinum plate, while a gold wire, one or two millimetres 
in diameter, and two or three centimetres long, forms the 
negative electrode. After some time—two or thre§ 
days if the amount of mercury present be very small— 
all of the mercury is removed from the solution and 
deposited on the gold wire, where its presence is indicated 
by its color. This color should not, however, be relied 
upon as conclusive, but the wire should be heated in a 
small tube, and the usual tests applied to the mercurial 
sublimate so obtained. 
§ 256. Since mercury is largely employed as a reme- 
dial agent, a quantitative estimation of that extracted 
from the organs or contents of the intestinal canal in 
cases of poisoning, is often highly important. For this 
purpose the preceding electrolytic method is quite satis- 
factory ; the gold wire is weighed before the operation, 
and again after the deposition of mercury is complete, 
and before heating in the tube. The increase in weight 
of course indicates the quantity of mercury present. 
100 parts of mercury correspond to 117.25 parts of 
calomel, or to 185.5 parts of corrosive sublimate. LEAD. 
LEAD. 
§ 257. Cases of acute poisoning by compounds of lead 
are of comparatively rare occurrence, and this may be 
understood if the unpleasant, astringent taste of these 
compounds, and the large dose required to produce dan- 
gerous effects, be borne in mind. On the other hand, 
preparations of lead are so largely employed in the arts, 
and the metal itself serves such a variety of purposes, 
that cases of chronic lead-poisoning are by no means 
infrequently encountered. The metal or one of its com- 
pounds may be inhaled in the form of dust, in printing 
offices, white-lead and minium factories, and paint shops. 
Lead is readily acted on by many chemical agents ; 
even pure aerated water will dissolve a notable quantity 
of lead, forming a hydrate, and the use of such water, 
after passing through lead pipes, for drinking or culinary 
purposes, may be followed by lead-poisoning. If the 
water contain carbonates or sulphates, even in small pro- 
portion, as do most river and spring waters, the surface 
of the metal soon becomes covered with a thin but in- 
soluble crust of lead carbonate or sulphate, and this pro- 
tects the metal from further corrosion. Hence leaden 
conduits may be safely employed for river waters, while 
the use of lead cisterns and pipes for the storage and 
conveyance of rain-water is highly dangerous. 
The glazing of common pottery and earthenware often 
consists of a highly basic silicate of lead. This is readily 
acted on, not only by acids, but also by pure aerated 
water, and the use of vessels so glazed for culinary pur- 
poses has frequently given rise to lead-poisoning. 
DETECTION IN ORGANIC MIXTURES. 
§ 258. If a solution suspected to contain lead be per- 
fectly clear, it needs no preparation, and hydrogen sul- 
phide is passed through it immediately, and until the 
liquid smells strongly of the gas. A black precipitate 
indicates the presence of lead. This precipitate, which 254 
DETECTION OF POISONS. 
is lead sulphide, is collected on a filter, and treated as 
directed farther on (§ 261). If the substance to be 
examined consist of both solid and liquid, the latter may 
be separated by filtration, and at once precipitated by 
hydrogen sulphide, the residue on the filter being exam- 
ined separately, or the organic matter may be destroyed, 
and the entire mass treated simultaneously. 
§ 259. Destruction of organic matter.—If the exam- 
ination of the liquid portion should fail in disclosing the 
presence of lead, it should not be at once concluded that 
none is present, for the metal may be contained in combi- 
nation with organic matter, or in some other insoluble 
form, in the solid or semi-solid matters left on the filter. 
This matter should, therefore, be mixed with sodium 
hydrate and ammonium nitrate, in suitable proportions, 
and the mixture evaporated to dryness, after which the 
residue is fused in a clay or porcelain crucible. Any 
lead present is thus converted into nitrate or nitrite. 
The residue is powdered, and dissolved in water acidu- 
lated with nitric acid ; the solution obtained is ready for 
precipitation by hydrogen sulphide. 
§ 260. When solid organic matters, such as animal 
tissues, arc to be examined for the presence of lead, 
the process described in § 236 may be employed. The 
mixture of hydrochloric acid and potassium chlorate will 
dissolve all of the lead compounds, even the metal itself. 
The lead chloride thus formed will remain in solution 
while the mixture is hot, but is usually partially pre- 
cipitated on cooling; by filtering the liquid at the boil- 
ing point, nearly if not quite all of the lead will pass into 
the filtrate, which is then immediately submitted to the 
action of hydrogen sulphide. Since some lead chloride 
may remain on the filter, the latter with its contents is 
treated as directed in § 259. 
§ 261. The precipitate formed by hydrogen sulphide 
is black when the gas has been passed through the solu- 
tion for a sufficient time, but may have a red color, due 
to a sulpho-chloride of lead, immediately when first 
formed. It is collected on a filter, and the filtration and 
washing are conducted as rapidly as possible, because LEAD. 
255 
moist lead sulphide becomes oxidized to sulphate more 
or less quickly on contact with the air. 
This precipitate is insoluble in either ammonia, ammo- 
nium carbonate,or ammonium sulphide. It is only slightly 
soluble in hydrochloric acid, readily in nitric acid. 
It is dissolved in boiling dilute nitric acid, lead nitrate 
being formed, but some insoluble lead sulphate is always 
formed at the same time ; this is separated by filtration, 
and tested as directed in § 262, a. 
§ 262. The clear filtrate is then mixed with a little 
ammonium nitrate, the mixture is evaporated to dryness, 
and the residue calcined in a porcelain crucible. When 
cold, the mass so obtained is boiled with water acidulated 
with a little nitric acid, and the solution is submitted to 
the following tests:— 
a) Sulphuric acid and solutions of the soluble sul- 
phates produce a white precipitate of lead sulphate, dis- 
tinguished by the following characters: it dissolves in 
potassium hydrate, in hydrochloric acid, tartaric acid, 
and in a boiling solution of ammonium acetate. It is 
colored black by hydrogen sulphide, and yellow by 
potassium chromate. 
5) Hydrochloric acid and solutions of the soluble 
chlorides produce a white precipitate, which redissolves 
when the liquid is boiled, but is again precipitated in 
brilliant crystalline scales as the solution cools. This 
precipitate is insoluble in ammonia, and unaffected by 
that reagent. When it is mixed with dry sodium car- 
bonate and heated in the inner blowpipe flame, a small 
globule of metallic lead is obtained; this globule is 
malleable, and may be easily flattened by the blow of a 
hammer. If it be heated in the outer blowpipe flame, it 
becomes oxidized, and produces a reddish-yellow incrus- 
tation on the charcoal. These blowpipe reactions are 
common to all compounds of lead. 
c) Potassium chromate gives a yellow precipitate of 
lead chromate, soluble in potassium hydrate. 
d) Potassium iodide produces a bright yellow pre- 
cipitate, soluble by the aid of heat, but again deposited 
in glittering, golden-yellow scales on cooling. 256 
DETECTION OF POISONS. 
e) Ammonia throws down a white precipitate, insoluble 
in excess. 
/) Potassium and sodium hydrate yield white precipi- 
tates, soluble m an excess of the reagent. 
Examination of Water suspected to contain 
Lead. 
§ 268. In cases of chronic lead-poisoning, the lead 
may often be traced to the water employed. The latter 
may contain sufficient of the metal to yield a more or 
less perceptible precipitate with hydrogen sulphide with- 
out concentration ; however, the analysis is always more 
easily made by evaporating the water to one-twentieth, 
or even one-fiftieth, of its volume, in a small porcelain 
capsule. It may be necessary to evaporate five or ten 
litres of the water, and in such a case small portions 
should be evaporated at a time, in the same capsule. 
The residue is dissolved in concentrated nitric acid, the 
solution evaporated to dryness, and the residue, which 
consists principally of sulphates and nitrates, is treated 
with distilled water, and the solution filtered. The fil- 
trate is subjected to the tests indicated in § 262. The 
residue on the filter may contain lead sulphate, and is 
tested according to § 262, a. 
QUANTITATIVE ESTIMATION. 
§ 264. The quantity of lead present may be most 
rapidly determined by converting the metal into sulphate, 
and weighing the latter. The precipitate of lead sulphide 
is boiled with concentrated nitric acid, the liquid is 
evaporated to dryness, and the residue is treated wTith 
concentrated sulphuric acid, and again evaporated, in 
order to expel all of the nitric acid. The temperature 
must finally be raised until no more vapors of sulphuric 
acid are disengaged. The whole operation, including the 
weighing, may be conducted in a tared porcelain cru- 
cible. 100 parts of lead sulphate contain 68.3 parts of 
lead. COPPER. 
257 
COPPER. 
§ 265. Like lead, copper is not often employed for 
the purpose of criminally destroying life, but it is not 
unfrequently introduced into the system accidentally in 
articles of food, with serious and sometimes fatal results. 
The principal cause of such accidents is the use of un- 
tinned copper vessels for culinary purposes ; and although 
such vessels, when perfectly clean, may be used without 
danger in the preparation of certain articles of food, the 
number of alimentary substances capable of acting upon 
and dissolving small quantities of the metal is so great, 
that it is far safer to avoid the use of untinned copper 
vessels in all culinary operations. Acid and fatty sub- 
stances especially, and liquids containing common salt 
and other saline matters in solution, should never be 
boiled in such vessels, since the quantity of copper dis- 
solved by them is sometimes so considerable as to impart 
a green or bluish color to the mixture. 
Imperfectly tinned copper vessels are, in this respect, 
more dangerous than such as are entirely untinned, be- 
cause the exposed portions of the copper are more rapidly 
acted on, by the electrolytic influence of the tin, than 
were no tin present. 
§ 266. It seems that small quantities of copper are 
very often, if not always, normally present in the human 
body especially in the liver. Therefore, in a toxicologi- 
cal investigation, it is of importance to determine the 
quantity of this metal that can be extracted from the 
liver, as a mere trace might not be abnormal. 
DETECTION IN ORGANIC MIXTURES. 
§ 267. In mixed animal or other substances, copper 
may exist in solution, or in combination with organic 
matters, or in some other form which is more or less in- 
soluble in water. For this reason, when the mixture to 
be examined consists of both solid and liquid matters, it 
should first be warmed with a little hydrochloric or 258 
DETECTION OF POISONS. 
acetic acid, by which the copper will be brought into 
solution. The liquid may then be filtered from the in- 
soluble portion, Avhich should be retained for subsequent 
examination (§ 268), or the whole of the organic matter 
may be at once destroyed, as may be selected. 
A decisive preliminary test may be made upon the fil- 
trate, thus : a few drops of the solution are placed upon 
a bright iron knife-blade, or any other polished iron sur- 
face, when, should any copper be present, it will be de- 
posited in the metallic state on the iron, and may readily 
be recognized by its red color. If desired, a needle or 
knife-blade may be immersed in the liquid, and will soon 
become covered with a film of copper ; but as a quantita- 
tive estimation may be necessary, it is more advisable to 
make the preliminary test upon as small a quantity of 
the liquid as possible, adding the remainder to the solu- 
tion obtained as described in the next section, or making 
a separate quantitative determination of the copper it 
contains, as will shortly be described. 
§ 268. Destruction of the Organic Matter.—The resi- 
due left upon the filter, together with any solid sub- 
stances, such as animal tissues, is finely divided and 
treated with hydrochloric acid and potassium chlorate as 
directed in § 236. The liquid thus obtained is boiled 
and filtered ; if desired, a preliminary test may be made 
upon the filtrate by placing a few drops of it on a clean 
knife-blade. A current of hydrogen sulphide is then 
passed through the clear solution, until it is completely 
saturated with the gas. If any copper be present, it 
will be thrown down as a black precipitate of cupric sul- 
phide. This precipitate has a great tendency to become 
oxidized, and must therefore be separated by rapid filtra- 
tion, and quickly washed with water that has been boiled 
to expel air, and which contains a little hydrogen-sul- 
phide. 
§ 269. The precipitate is dissolved in nitric acid, 
and the copper thus converted into cupric nitrate; the 
solution is greenish-blue, and may still contain organic 
matter which had been thrown down with the cupric sul- 
phide. It is therefore made strongly acid, some ammo- 
nium nitrate is added, and the whole is evaporated to COPPER. 
dryness ; the residue is calcined until all of the organic 
matter is destroyed, and is then dissolved in water 
slightly acidulated with nitric acid. The solution is sub- 
mitted to the following tests:— 
a) Ammonia produces a bluish-white precipitate, which 
dissolves in an excess of the reagent, forming a dark- 
blue solution. 
b) Potassium ferrocyanide gives a mahogany-colored 
precipitate, even in very dilute solutions of copper. Mere 
traces of the latter metal produce only a reddish-brown 
color, which can be best seen by holding the test-tube 
in front of a sheet of white paper, or other white surface. 
The liquid to which this test is applied must be acid, 
since the precipitate is soluble in ammonia and the alka- 
line hydrates. 
e) A drop of the solution placed upon a clean iron 
surface will deposit a film of metallic copper. 
d) Potassium or sxlium hydrate will throw down a 
pale-blue precipitate of cupric hydrate, which becomes 
converted into black, anhydrous cupric oxide when boiled. 
If some glucose be added to the cupric solution before 
the alkaline hydrate, no precipitate is formed on the ad- 
dition of the latter, but on boiling the solution, cuprous 
oxide, which is red, is immediately thrown down. 
e) If the solution obtained by dissolving the precipi- 
tated cupric sulphide in nitric acid be introduced into a 
platinum crucible or capsule, which is connected with 
the negative pole of a voltaic battery, while a platinum 
plate suspended in the liquid in the crucible constitutes 
the positive pole, in the course of several hours, accord- 
ing to the strength of the electric current, all of the cop- 
per will be removed from the solution and deposited on 
the interior of the platinum vessel. This test is very 
delicate, and may be applied to the quantitative estima- 
tion of copper, the weight of the crucible without the 
deposit of copper being known. The copper may be 
dissolved from the platinum vessel by nitric acid, and the 
preceding tests made subsequent to the quantitative de- 
termination, if so desired. DETECTION OF POISONS. 
Quantitative Estimation. 
§ 270. Copper is usually estimated in the form of 
cupric oxide, CuO. Should organic matter have been 
destroyed by hydrochloric acid and potassium chlorate, 
the precipitated sulphide is dissolved in nitric acid, and 
any remaining traces of organic matter are destroyed as 
directed in § 269. The residue is dissolved in dilute 
nitric acid, and the solution is again precipitated by 
hydrogen sulphide. The precipitate is redissolved in 
nitric acid; the solution is evaporated to dryness in a 
covered porcelain crucible, and the residue is gradually 
heated to bright-redness. The cupric oxide thus formed 
may contain some cuprous oxide ; it is therefore moist- 
ened with concentrated nitric acid, again calcined, and 
after cooling is ready for weighing. 
Ashes, and the residue from the deflagration of organic 
matter, are exhausted with nitric acid, the solution is 
precipitated by hydrogen sulphide, and the operation 
continued as just described. 100 parts of cupric oxide 
correspond to 79.87 parts of metallic copper. 
Copper may also be separated in the metallic state by 
electrolysis, and weighed directly, as mentioned in the 
preceding section, should no other metal be present 
which would be deposited at the same time. ZINC. 
261 
ZINC. 
§ 271. Accidents have occurred from the unintentional 
introduction of compounds of zinc into the system, and 
zinc sulphate has sometimes been administered with crim- 
inal intentions. Besides this, zinc sulphate, or white 
vitriol, as it is commonly called, is often given as an 
emetic in cases of poisoning, so that it may be encoun- 
tered in toxicological examinations, and the analyst must 
be familiar with its reactions. 
The destruction of organic matter is accomplished by 
hydrochloric acid and potassium chlorate, and the mix- 
ture is filtered as directed in 236. Zinc is not preci- 
pitated by hydrogen sulphide from solutions containing 
free mineral acids ; therefore, hydrogen sulphide is first 
passed through the filtrate, and any precipitate that may 
form is separated by filtration, and examined for such 
other metals as may be indicated by its color. 
An excess of ammonia is then added to the filtrate, 
and should any precipitate be formed, the liquid is again 
filtered. Hydrogen sulphide is passed through the clear 
solution, and if zinc be present a white precipitate of 
zinc sulphide will be thrown down. 
It is collected on a filter, and rapidly washed with 
tolerably concentrated acetic acid, after which it is dis- 
solved in a little nitric acid ; the solution so obtained is 
evaporated to dryness, and the residue calcined and dis- 
solved in water acidulated with nitric acid. The solu- 
tion of zinc nitrate is filtered, if necessary, and tested as 
follows:— 
a) Add sufficient sodium acetate to react with the zinc 
nitrate and nitric acid, and replace all of the free nitric 
acid by acetic acid. Hydrogen sulphide or ammonium 
sulphide will then produce a white precipitate of zinc 
sulphide. 
h) Potassium ferrocyanide produces a white precipi- 
tate, insoluble in dilute acids, but soluble in potassium 
hydrate, by the aid of heat, and reprecipitated from this 
solution on the addition of hydrochloric acid. 262 
DETECTION OF POISONS. 
c) Potassium or sodium carbonate gives a white pre- 
cipitate of basic zinc carbonate, insoluble in an excess of 
the reagent. If this precipitate be boiled in the liquid 
in which it was formed, and then collected on a filter, 
washed, and dried, it may be ignited in a porcelain 
crucible, and will be converted into zinc oxide, which is 
yellow while hot, and white when cold. 
DETECTION OF ACIDS. 
§ 272. Certain acids only act as poisons when they 
are introduced into the stomach in a concentrated state ; 
such are the mineral acids, sulphuric, hydrochloric, and 
nitric. The compounds of these acids with bases that 
are not themselves poisonous, ma*y often be safely in- 
gested in comparatively large doses, and even dilute 
solutions of the acids may sometimes be freely taken 
into the stomach without ill effects. Other acids, such 
as tartaric and citric, may be safely administered in a 
concentrated state, in small doses, and produce poisonous 
effects only when taken in large quantities. On the other 
hand, some acids are always poisonous, in whatever 
quantity or state of concentration they may be taken ; 
their soluble salts, and some of their insoluble salts, also 
possess poisonous properties. Notable examples are 
oxalic and hydrocyanic acids. 
The three principal mineral acids, sulphuric, hydro- 
chloric, and nitric, have frequently been employed as 
criminal poisons and as means of suicide, and it is neces- 
sary that the medical chemist shall be able to identify 
them, either mixed with organic matters, such as the 
contents of the stomach, or vomited matters, or in the 
stains which these acids produce on clothing or other 
fabrics. 
Generally, the highly acid reaction of the material 
under examination is a sufficient index to the nature of 
the poison, and the task of the analyst is facilitated ; MINERAL ACIDS AND OXALIC ACID. 
263 
but in case an alkaline antidote, such as an alkaline car- 
bonate, magnesia, or chalk, has been administered, it 
becomes necessary to seek for the acid in a saline com- 
bination. An aqueous extract of the matters may then 
be first examined, and the manner in which this responds 
to the tests will usually be sufficient to distinguish be- 
tween the sulphates and chlorides which would naturally 
be expected to be present, and the large excess of these 
salts that 'would indicate a probable poisoning. 
§ 273. The following method of procedure, proposed 
by Roussin, may be relied upon for the detection of the 
three acids in question when they are present in the free 
state : — 
The liquid portion of the matter is separated by filtra- 
tion, and the solid parts are washed with water, which 
is then united with the filtrate. The latter is evaporated 
to dryness, in a retort provided with a receiver, and 
heated to a temperature not above 110°, on an oil-bath. 
a) Nitric acid, if present, produces red fumes towards 
the end of the operation, and the distilled liquid will give 
a rose or brown tint when mixed with a concentrated 
solution of ferrous sulphate and strong sulphuric acid. 
£>) Sulphuric acid will react with the organic matter, 
and be reduced to sulphurous acid, which can be detected 
in the distillate. In this case, the residue in the retort 
becomes charred and blackened. 
c) Hydrochloric acid will pass into the distillate, and 
may be detected by the addition of silver nitrate. As 
a small quantity of hydrochloric acid is obtained by dis- 
tilling the normal contents of the stomach, unless the 
precipitate of silver chloride be somewhat abundant, it 
must not be too hastily decided that hydrochloric acid 
in poisonous quantity was present. In such a case, it is 
necessary to make a quantitative estimation. 
d') Oxalic acid, if present, would remain in the retort, 
the contents of which would not be blackened. The re- 
sidue is treated writh alcohol, and the liquid so obtained 
is filtered, and tested with calcium acetate, with wfiich 
oxalic acid forms a white precipitate of calcium oxalate, 
soluble in mineral acids, especially hydrochloric, but in- 
soluble in acetic acid. DETECTION OF POISONS. 
Sulphuric Acid. 
§ 274. The presence of free sulphuric acid may be 
easily detected, even when mixed with a large proportion 
of organic matter. If the mixture be viscid or semi- 
solid, it is diluted with water to such a consistence that 
it may be filtered. Solution of barium chloride is added 
to the filtrate, and, if sulphuric acid be present, a white 
precipitate of barium sulphate is thrown down, and this 
precipitate is insoluble in nitric acid, even by the aid of 
boiling. It is collected on a filter, dried, mixed with an 
excess of powdered charcoal, and heated to whiteness in 
a small porcelain crucible. Barium sulphate is thus re- 
duced to barium sulphide, which will disengage hydrogen 
sulphide when moistened with hydrochloric acid. 
Sulphuric acid, whether free or in combination, is 
readily detected in this manner. Should the acid have 
been partially neutralized by the administration of an 
antidote, the presence of small quantities of free acid 
may be detected as directed in § 273. However, it is 
not often that any serious uncertainty can exist as to 
whether the sulphuric acid found mixed with organic 
matter was or was not uncombined, especially in cases of 
suspected poisoning, since the corrosive effects of the acid 
upon the parts with which it has come in contact, or other 
corroborative circumstances, will generally of themselves 
furnish evidence sufficiently conclusive. 
§ 275. The blue liquid commonly known as sulphate of 
indigo, has frequently been criminally employed by poi- 
soners and by suicides. It is made by dissolving indigo 
in fuming sulphuric acid, and diluting the solution with 
water, and is used by dyers, and sometimes as a washing- 
blue. The deep blue color of the substances under ex- 
amination leads the analyst to suspect the presence of 
indigo, and the latter is easily characterized by the red- 
dish-yellow color which it assumes when heated with 
nitric acid. When sulphate of indigo is boiled with ni- 
tric acid, the indigo is converted into a substance called 
isatine, and sulphuric acid may then be detected in the 
solution by means of barium chloride, as previously de- 
scribed. Indigo is transformed into white-indigo when HYDROCHLORIC ACID. 
265 
boiled with glucose and milk of lime, but the blue color 
is gradually restored by contact with the air. 
Hydrochloric Acid. 
§ 276. Since chlorides may always be expected to be 
naturally present in such mixtures as the contents of the 
stomach and vomited matters, it is of little service to 
apply tests directly to the clear portions of such mixtures. 
Besides this, silver nitrate, which is used in testing for 
hydrochloric acid and chlorides, precipitates a great 
number of organic substances, and these must therefore 
he eliminated before applying the test. This is accom- 
plished, as indicated in § 273, by distilling to dryness 
the liquids to be examined, and testing only the portion 
which distils. All of the free hydrochloric acid will be 
found in the distillate, and could only be mistaken for a 
few other volatile acids, from which subsequent tests will 
at once distinguish it. 
If hydrochloric acid be present, the contents of the 
receiver will be acid, and will produce a white, curdy 
precipitate with solution of silver nitrate; this precipi- 
tate consists of silver chloride; it is insoluble in nitric 
acid, but dissolves readily in ammonia. On exposure to 
light, it rapidly darkens in color, and becomes violet or 
bluish-black. 
§ 277. Quantitative estimation.—As has already 
been mentioned, hydrochloric acid is always obtained by 
distilling matters which may normally be found in the 
stomach, since free hydrochloric acid exists in the gastric 
juice. The quantity of the acid derived from this source 
is, however, so small that it may readily be distinguished 
from the comparatively large quantity usually to be 
found when the acid has been swallowed. Such dis- 
tinction must be made by a quantitative analysis. 
The silver chloride obtained by precipitating the dis- 
tilled liquid by an excess of silver nitrate is collected on 
a filter and thoroughly washed with distilled water; after 
drying, the filter is burned separately, and both ash and 
precipitate are heated to redness in a tared porcelain 266 
DETECTION OF POISONS. 
crucible. It is then weighed; 100 parts of silver chloride 
correspond to 25.48 parts of hydrochloric acid. 
It is well also to distil a mixture similar to that sus- 
pected to contain hydrochloric acid, and to estimate the 
amount of hydrochloric acid in the filtrate. A direct 
comparison may then be made between the quantity 
found in the suspected mixture, and that which might be 
expected to be normally present. 
Nitric Acid. 
§ 278. As nitric acid only exists in’inappreciable 
quantities, if at all, in the substances such as vomited 
matters, the digestive organs and urine, usually sub- 
mitted to toxicological examination, the presence of the 
smallest trace of this body may be regarded as abnormal. 
Again, nitric acid poisoning may usually be recognized 
without difficulty by the peculiar yellow stains which 
the acid imparts to the epidermic tissue; this coloration, 
however, is not always wyell marked on the mucous mem- 
brane of the digestive organs. 
The chemical analysis is made upon an aqueous ex- 
tract of the matters. This is filtered, neutralized with 
potassium carbonate, and evaporated to dryness on a 
water-bath. The residue will contain potassium nitrate, 
which may be deposited in a crystalline form, if there be 
not too much organic matter present. It is redissolved 
in the smallest possible quantity of water, and the solu- 
tion is filtered, and tested as follows:— 
а) A portion of the filtrate is gently heated in a test- 
tube with a small piece of copper wire or foil and strong 
sulphuric acid. If nitric acid be present, orange-colored 
vapors will be disengaged. 
б) Another portion is mixed with a solution of ferrous 
sulphate, and poured, without mixing, upon strong sul- 
phuric acid, in a test-tube. The presence of nitric acid 
will then be indicated by a rose-colored or brown ring at 
the surface of contact of the two liquids. It should be 
ascertained that the color is not produced by the sus- 
pected solution and sulphuric acid alone, as might be the 
case should certain organic substances be present. MINERAL ACIDS IN STAINS ON CLOTHING. 
c) A third portion is treated with an excess of potas- 
sium hydrate, and evaporated to dryness. Ammonia 
may be given oft', in which case the residue is heated on 
the water-bath until no more ammoniacal odors are 
perceptible; a second treatment with potassium hydrate 
may be necessary to expel all of the ammonia. The 
residue is then dissolved in about four times its volume 
of water, and heated with platinized zinc, or with alu- 
minium wire or filings. Should nitric acid be present, 
it will be reduced by the nascent hydrogen; ammonia 
will be disengaged, and may be recognized by its odor 
and by the white fumes which are produced when a rod 
moistened with hydrochloric acid is held near the mixture. 
d) A fourth portion of the solution is mixed with about 
its own volume of concentrated sulphuric acid, a few 
drops of sulphate of indigo are added, and the mixture is 
heated. If nitric acid be present, the indigo will be 
decolorized. This reaction is hardly applicable when the 
suspected solution has a dark color. 
Detection of Mineral Acids in Stains on 
Clothin g. 
§ 279. Should the stains be quite recent, the acid may 
usually be detected by cutting out the stained part, 
boiling it with water, and testing the solution, as has 
been indicated, for the several acids. 
Sulphuric acid stains are generally somewhat moist, 
and have a brown or red color, but the color varies with 
the nature of the material and the dye. They nearly 
always disappear when moistened with ammonia. 
Owing to the volatile nature of hydrochloric acid, it is 
often impossible to satisfactorily prove its presence in a 
stain. 
Nitric acid stains are usually brown or yellowish, and, 
unlike those caused by sulphuric acid, soon become dry, 
and destroy the fabric. They are not modified by alco- 
hol, ether, or benzol, but assume an orange color when 
moistened with potassium hydrate or ammonia. DETECTION OF POISONS. 
Oxalic Acid. 
§ 280. Oxalic acid may be separated from organic 
mixtures by evaporating the latter to dryness, and ex- 
tracting the residue Avith alcohol acidulated Avith hydro- 
chloric acid. It may he necessary to perform this ex- 
traction tAvice, and should lime or magnesia have been 
administered as an antidote, so that an insoluble oxalate 
is present, the residue from the alcoholic extraction must 
he boiled Avith dilute hydrochloric acid, Avhich, after fil- 
tration, is added to the alcoholic extract. The latter is 
then evaporated, and after the alcohol has been expelled, 
the aqueous solution is filtered, if necessary, and tested 
by the folloAving reactions. 
a) A portion of the liquid is exactly neutralized Avith 
ammonia, and lime-Avater or solution of calcium sulphate 
is added: oxalic acid Avill occasion the formation of a 
Avhite precipitate of calcium oxalate, insoluble in acetic 
acid, hut soluble in hydrochloric acid, and reprecipitated 
from this solution on the addition of ammonia. If this 
precipitate he collected, Avashed, dried, and calcined at a 
high temperature, it Avill leave a residue of lime, Avhich 
will restore the blue color to moistened red litmus paper, 
and change to broAvn the yelloAV color of turmeric. 
1) Lead acetate or subacetate throws down a white 
precipitate of lead oxalate. This reaction may he applied 
to the separation of oxalic acid from organic mixtures : 
a solution of lead acetate is added to the mixture as long 
as it produces any precipitate ; the lead oxalate throAvn 
down is collected on a filter, Avell Avashed, suspended in 
Avater, and decomposed by a stream of hydrogen sulphide. 
Lead sulphide is formed, and is deposited, together with 
most of the organic matter Avhich Avas precipitated with 
the lead oxalate, while oxalic acid enters into solution 
and is separated by filtration. When the clear filtrate 
is sufficiently evaporated, the acid is deposited in small, 
needle-like crystals, Avhich are generally almost colorless. 
c) Silver nitrate produces a white precipitate of silver 
oxalate in solutions containing oxalic acid or an oxalate. 
If this precipitate be dried and gently heated on a piece HYDROCYANIC ACID. 
269 
of platinum foil, it becomes brown or black, and decom- 
poses with a slight explosion. 
§ 281. Quantitative estimation.—In order to de- 
termine the quantity of oxalic acid in a liquid containing 
the free acid or one of its salts, the solutionis acidulated 
with acetic acid, and precipitated by calcium chloride ; 
the mixture is then boiled and filtered. The precipitate 
left on the filter is washed, dried, and ignited in a fared 
crucible. After cooling, the residue is moistened with a 
saturated solution of ammonium carbonate, and again 
heated to incipient redness. All of the calcium oxalate 
is thus converted into calcium carbonate, which may nowr 
be weighed. 100 parts of calcium carbonate correspond 
to 126 parts of crystallized oxalic acid. 
HYDROCYANIC ACID (PRUSSIC ACID). 
§ 282. Hydrocyanic acid and its soluble compounds 
are frequently the agents of accidental and criminal poi- 
soning. The poisonous nature of the cyanides is due to 
the liberation of hydrocyanic acid by the action of the 
acids contained in the gastric juice. The presence of 
this acid may usually be detected, even when very much 
diluted, by its peculiar smell which recalls that of 
crushed peach-kernels. Hydrocyanic acid is very vola- 
tile, and is at the same time quite unstable, and soon de- 
composes, especially in the presence of organic matter, 
so that unless the chemical examination be made shortly 
after the suspected poisoning, all traces of the acid may 
have disappeared, although comparatively large quantities 
were originally present. 
§ 283. The following tests may be made directly upon 
the suspected substance, and are not invalidated by the 
presence of organic matters or other foreign compounds: 
a) A portion of the suspected matter is acidulated, if 
DETECTION OF HYDROCYANIC ACID VAPORS. DETECTION OF POISONS. 
neutral or alkaline, with dilute sulphuric acid and placed 
in a watch-glass, over which is inverted another similar 
watch-glass in which a drop of a solution of silver nitrate 
has previously been placed. The silver nitrate solution 
must not he allowed to flow into the lower glass. This 
test may also be made by inverting a watch-glass con- 
taining a drop of silver nitrate over the jar in which the 
suspected substance has originally been placed. If 
hydrocyanic acid be present, the silver nitrate solution 
will soon become turbid, and the reaction may be hastened 
by warming the lower vessel. The turbidity is caused 
by the formation of silver cyanide ; the precipitate does 
not change color on exposure to light, and is soluble in 
hot nitric acid; it is thus distinguished from silver 
chloride, which would be formed were any free hydro- 
chloric acid present in the suspected mixture. If this 
test yield affirmative results, all of the following tests 
should he applied; hut, if the results be negative, other 
tests applied directly for the detection of the vapor will 
probably he fruitless. 
5) A watch-glass holding some of the suspected sub- 
stance, or. the vessel originally containing it, has inverted 
over it, as in the preceding experiment, a watch-glass in 
which a drop or two of a solution of potassium hydrate 
has been placed. On warming the lower glass, hydro- 
cyanic acid will volatilize, and, reacting with the potas- 
sium hydrate, will form potassium cyanide. After the 
lapse of five or ten minutes, the upper glass is removed, 
and the spot is touched with a drop of ferrous sulphate 
and a drop of ferric chloride ; one or two drops of dilute 
hydrochloric acid are then added, when, should hydro- 
cyanic acid have been present, a blue precipitate (Prus- 
sian blue) will be formed. This test is usually known 
as the iron test, and is without fallacy, but demands care 
in its manipulations. 
c) Liebig's test is made in a similar manner, hut the 
upper watch-glass contains only a drop of yellow ammo- 
nium sulphide. If hydrocyanic acid be present, the 
ammonium sulphide will soon become colorless, and when 
this is accomplished, which may require fifteen minutes 
or half an hour, the upper glass is removed ; it will con- HYDROCYANIC ACID. . 
tain ammonium sulphocyanate, formed by the reaction of 
the hydrocyanic acid and ammonium sulphide, and when 
this is touched with a drop of ferric chloride a blood-red 
color is produced. It is sometimes recommended to 
evaporate the ammonium sulphocyanate to dryness befoi-e 
adding the ferric chloride, but, if the yellow ammonium 
sulphide be completely decolorized, this is not necessary. 
The red color is bleached by solution of mercmdc nitrate, 
and is thus distinguished from that which might possibly 
be produced under similar circumstances by acetic acid. 
DETECTION OF HYDROCYANIC ACID IN SOLUTION. 
§ 284. The mixture of organic matter or other sub- 
stance suspected to contain hydrocyanic acid, is, if neu- 
tral or alkaline, acidulated with dilute sulphuric acid, 
and introduced into a retort, the neck of which is slightly 
inclined upwards, and in communication with a Liebig’s 
condenser inclined downwards. The retort is then heated 
in an oil-bath to a temperature not above 110°, and the 
contents are distilled until about one-eighth of the liquid 
has passed over. The distillate is submitted to fractional 
distillation, collecting about 3 c.c. for every 100 c.c. of 
liquid, and changing the recipient between every 3 c.c. 
Hydrocyanic acid, if present, will be found in the first 
fractions, and, if in any: quantity, may be recognized by 
its odor. 
The distilled liquid is tested as follow's:— ■ 
a) Silver nitrate produces a white precipitate, soluble 
in ammonia and hot nitric acid. This precipitate is col- 
lected on a filter, washed, and dried ; if a sufficient quan- 
tity of it be obtained, a portion may be heated in a small 
tube ; cyanogen gas will be disengaged, and wdien lighted 
will burn at the mouth of the tube with a purple flame, 
wdiile a black residue remains in the tube. 
Place a very small fragment of iodine at the bottom 
of a small tube closed at one end, and above it as much 
as can be spared of the supposed silver cyanide. Apply 
a very gentle heat, by holding the tube at some distance 
above a flame, when cyanogen iodide will be formed, and 
will condense in the cool part of the tube in fine, white 272 
DETECTION OF POISONS. 
needles. If very little silver cyanide be used, it is well 
to cover it with a layer of sodium carbonate, to retain 
any excess of iodine. Cut off’ that portion of the tube 
which contains the sublimate, and warm it in a test-tube 
with a little dilute ammonium sulphide, in which it will 
dissolve. Evaporate the solution to dryness in a porce- 
lain capsule on a water-bath, and treat the residue with 
a drop of ferric chloride ; a blood-red color will be pro- 
duced. 
b) Add to some of the distilled liquid a solution of 
potassium hydrate, and then a few drops of ferrous sul- 
phate and a drop of ferric chloride, and boil. After 
cooling, add a slight excess of dilute hydrochloric acid. 
If the liquid contained hydrocyanic acid, a blue precipi- 
tate of ferric ferrocyanide (Prussian blue) is formed, 
either immediately or after standing for a few hours. 
c) Another portion of the distillate is evaporated to 
dryness with a few drops of yellow ammonium sulphide 
(or if the latter be completely decolorized after boiling, 
the evaporation is not necessary), and tested with a few 
drops of ferric chloride. Hydrocyanic acid will thus 
have been converted into ammonium sulphocyanate, and 
this produces a blood-red color with ferric salts. 
QUANTITATIVE ESTIMATION. 
§ 285. A known weight of the substance is distilled, 
as has already been described, and the distillate is recti- 
fied over borax, in order to remove all traces of hydro- 
chloric acid which might be present. The distilled liquid 
is precipitated by an excess of silver nitrate, and the 
silver cyanide thrown down is collected on a tared filter, 
carefully washed, and dried at 100°. It is then weighed 
in the filter, and the weight of the latter deducted. 100 
parts of silver cyanide correspond to 20.15 parts of an- 
hydrous hydrocyanic acid. PIIOSPHOllUS. 
273 
PHOSPHORUS. 
§ 286. The almost universal use of phosphorus matches, 
the ease with which rat poisons containing phosphorus 
may be obtained, the general knowledge of the poisonous 
properties of these preparations, and the small dose re- 
quired to produce death, have combined to render phos- 
phorus one of the most common agents of criminal and 
accidental poisoning. 
If the substance to be examined has not been long ex- 
posed to the air, it may contain phosphorus in' the free 
state; hut in many cases, oxidation will have converted 
the phosphorus into phosphorous acid or phosphoric acid. 
Since this last is a normal constituent of the body and 
of the food, it would afford no evidence of the admin- 
istration of phosphorus, hut it may he considered as 
proven that in most cases phosphorus may be detected 
after several weeks’ time, in a body on which no previous 
autopsy has been made. 
If possible, the vomited matters should he examined, 
as they have been found to contain the largest proportion 
of phosphorus; hut unless this examination he made 
promptly, all of the poison may he oxidized. The oxi- 
dation or non-oxidation of phosphorus in such matters 
depends on various circumstances, almost impossible to 
understand or foresee : in some cases the poison has been 
found unaltered after the lapse of several months, in 
others it has been wholly oxidized within two or three 
days. 
The organic matter should first he examined as to its 
odor, that of phosphorus being very characteristic, and 
as to its luminosity in the dark. It should be also as- 
certained whether any solid particles of the phosphorus 
compound can he detected mechanically. 
§ 287. The suspected matter is then acidulated with 
dilute sulphuric acid, a little water is added, if necessary, 
and the mixture is introduced into a glass flask. By 
means of a glass tube, two or three centimetres in diameter 
and fifty or sixty centimetres long, bent twice at right 274 
DETECTION OF POISONS. 
angles, the flask is connected with a vertical Liebig’s 
condenser, made wholly of glass. The apparatus is 
placed in a perfectly dark room, and the liquid in the 
flask is heated: as soon as it enters into ebullition, if 
phosphorus be present, luminous vapors will appear in 
the flask, and gradually extend into the tube, becoming 
permanent at the point at which the aqueous vapor be- 
gins to condense. The appearance of luminous vapors 
is characteristic of the presence of free phosphorus, and 
should any quantity of the latter be present, it will be 
found in the form of minute globules in the distilled liquid. 
This process, suggested by Mitscherlich, is exceedingly 
delicate. 
§ 288. Fresenius and Neubauer combine the method 
of Mitscherlich with one which was suggested by Dussard 
and Blondlot. After the phosphorescence has ceased in 
the flask and tube, a solution of silver nitrate is added 
to the distilled liquid, and the distillation is continued 
for some time longer. The precipitate formed by the 
silver nitrate is collected, well washed,, and introduced 
into a capacious apparatus for generating hydrogen by 
means of zinc and dilute sulphuric acid. The stream of 
gas evolved is freed from all traces of hydrogen sulphide 
by being passed through a U tube filled with pumice- 
stone impregnated with potassium hydrate, and is burned 
at a platinum jet. Under these circumstances, pure hy- 
drogen will burn with an almost invisible flame, but the 
presence of phosphorus communicates a characteristic 
greenish color to the flame. 
After the detection of phosphorus by this colored 
flame, the gas may be passed into a solution of silver 
nitrate, where it will occasion a dark precipitate of silver 
phosphide ; this is collected, washed, boiled with a little 
strong nitric acid, and the solution is evaporated to dry- 
ness. On adding a little water, and a drop of very 
dilute ammonia, a yellow color or precipitate of silver 
phosphate will be formed. ALKALOIDS IN ORGANIC MIXTURES. 
275 
DETECTION OF ALKALOIDS IN ORGANIC 
MIXTURES. 
§ 289. The active principles of most vegetable poisons 
may generally be recognized without great difficulty 
when in a pure state, but when they exist in complex 
organic mixtures their detection often becomes one of 
the most trying problems of the toxicological expert. 
The foreign matter present cannot be destroyed, for the 
agents by which such destruction could be accomplished 
would in nearly all cases decompose the poison ; it there- 
fore becomes necessary to separate the alkaloid, in as 
pure a state as possible, from the foreign substances. 
In the operations necessary for this purpose, the extracts 
must be reduced to the smallest possible volume, the 
reagents used must be employed in small quantities, and 
the solutions used as tests must be applied by delicate 
glass rods ; for it must be remembered that the poison 
may be present in exceedingly small quantity, and that 
it is often impossible to separate more than a small pro- 
portion of that quantity in a sufficiently pure state to be 
tested. 
We will only consider a few of the more commonly 
occurring alkaloids, first giving a general outline of the 
processes by which they may be separated from complex 
organic mixtures, and recognized by their characteristic 
reactions. 
§ 290. The method proposed by Stas for the separa- 
tion of the alkaloids, depends upon the fact that the free 
alkaloids are generally soluble in ether, but not in water; 
while their salts are soluble in aqueous liquids ; hence 
when an alkaloid is set free from one of its combinations 
dissolved in water, and the mixture is agitated with 
ether, the latter takes up the free alkaloid, and leaves 
it in a comparatively pure state on evaporation. 
If the suspected substance be liquid, or if it consist of 
both solid and liquid, it is mixed with about twice its vol- 
METHOD OF STAS. 276 
DETECTION OF POISONS. 
ume of strong alcohol containing from 0.5 to 2 grammes 
of tartaric acid, and the mixture is digested at about 
70°, on a water-bath. If the matter be solid, such as 
the tissues of the stomach, liver, etc., it is cut into small 
pieces and digested at about 70°, with strong alcohol 
acidulated with tartaric acid as before; it is then pressed 
in a cloth, and the digestion with acid alcohol is repeated 
several times. The alcoholic solution is allowed to cool, 
filtered, and the residue on the filter is wrell washed with 
alcohol, the washings being added to the filtrate. The 
latter is then transferred to a retort, and evaporated at 
a temperature of about 35°, the distillation being hast- 
ened, if desired, by a current of air drawn through the 
liquid, by the aid of an aspirator. When the greater 
part of the alcohol has passed over, the operation is ar- 
rested, and the liquid is allowed to cool, and filtered 
through a filter which has previously been moistened 
with water. The acid filtrate is now agitated in a small 
flask or test-tube with several times its volume of ether; 
the latter is removed by decantation, as soon as it sep- 
arates, and the operation is repeated with fresh ether as 
long as the latter continues to take up coloring matter. 
The ethereal solution may contain colchicine, digitaline, 
and foreign matters ; the alkaloids remaining in the form 
of salts in the aqueous liquid, which is then mixed with 
powdered glass, to prevent the residue from becoming a 
solid mass, and evaporated to dryness in a vacuum or 
under a hell-jar over sulphuric acid. The residue is 
carefully triturated with absolute alcohol, and allowed to 
macerate for about twenty-four hours. The solution is 
then filtered, and the new filtrate is cautiously evaporated 
to dryness at a temperature not above 35°. The residue 
is dissolved in a very small quantity of water, potassium 
or sodium carbonate is added in sufficient quantity to 
set free the alkaloid, and the liquid is immediately agi- 
tated with four or five times its volume of pure ether. 
The ethereal layer is rapidly decanted, as soon as it 
separates, filtered into a watch-glass, and allowed to eva- 
porate spontaneously. The residue in the watch-glass will 
contain the alkaloid, which may form oily streaks on the 
sides of the glass (conine, nicotine) or may he either 
an amorphous or a crystalline solid. METHOD OF STAS. 
§ 291. The method of Stas answers very well for the 
separation of most of the alkaloids, and it has the un- 
doubted advantage of leaving the poison in a nearly pure, 
and sometimes crystalline, condition. In the case of 
morphine, unless the manipulations with ether he exe- 
cuted with great rapidity, all of the alkaloid may sepa- 
rate in the crystalline state from the alkaline aqueous 
liquid, morphine being insoluble in ether, and no trace 
of it can then be found in the ethereal solution. 
Various methods have been employed to obviate the 
difficulty occasioned by the exceedingly slight solubility 
of some of the alkaloids in ether. Rodger and Gird- 
wood proposed to replace the latter solvent by chloro- 
form, and this agent is. especially well adapted for the 
separation of strychnine. Uslar and Erdmann preferred 
hot amylic alcohol, and, since morphine is quite soluble 
in this menstruum, while it is insoluble in ether, their 
process is applicable for the separation of that alkaloid ; 
but amylic alcohol must be separated by the application 
of direct heat, and consequently the alkaloid is rarely 
deposited in a crystalline form. 
GENERAL REAGENTS FOR THE DETECTION OF ALKALOIDS. 
Various reagents have been proposed for the purpose 
of distinguishing the alkaloids from other bodies for 
which they might be mistaken. None of these are 
equally applicable to the whole class of compounds, and 
the nature of the body supposed to be an alkaloid must 
be decided by the totality of its properties. Sodium 
phosphomolybdate,—made by dissolving washed ammo- 
nium phosphomolybdate in sodium hydrate, evaporating 
to dryness, and calcining the residue, which is then dis- 
solved in very dilute nitric acid,—precipitates all of the 
ordinary alkaloids. Mercuro-potassium iodide (mercuric 
chloride 13.546 gr., potassium iodide 49.8 gr., water one 
litre) is perhaps the most delicate general reagent for 
the alkaloids, forming with them precipitates which are 
usually crystalline. Circumstances will generally have 
pointed to the probable presence of a particular alkaloid, 
in which case these general tests will only be confirmatory. 278 
DETECTION OF POISONS. 
CONINE. 
§ 292. This alkaloid may be readily separated from 
organic mixtures by the process of Stas. After the 
evaporation of the ethereal solution of the alkaloid, oily 
drops or streaks will remain upon the watch-glass, and 
these will have the peculiar smell of conine, resembling 
that of hemlock ; but this odor may in some cases be 
more or less marked by that of animal matters. Conine 
is soluble in about one hundred parts of water, and is 
freely soluble in alcohol, ether, chloroform, and benzol. 
Chemical tests.—If a Avatch-glass containing a drop of 
hydrochloric acid be inverted over the glass containing 
the conine, the two glasses become filled with dense white 
fumes, and the conine is converted into a mass of crys- 
talline needles of conine hydrochloride. If the conine 
be in aqueous solution, fumes appear in the glasses, 
conine hydrochloride is formed as before, and crystal- 
lizes from the solution when the latter is allowed to eva- 
porate spontaneously. When conine is treated with 
strong aqueous hydrochloric acid, a red color is devel- 
oped, and the liquid deposits crystals when sufficiently 
concentrated. 
Solution of gold trichloride gives a bright-yellow, 
amorphous precipitate with solutions of conine or of its 
salts. 
Iodine dissolved in aqueous potassium iodide, yields a 
reddish-brown, amorphous precipitate, which soon turns 
yellow, and redissolves in the liquid, unless an excess of 
iodine be present. 
If chlorine water be added to an aqueous solution of 
conine, the mixture becomes turbid. 
Solution of tannin forms a white, amorphous precipi- 
tate, soluble in a small quantity of hydrochloric acid, 
but re precipitated on the addition of more acid. 
Mercuric chloride gives, in aqueous solutions of conine, 
a white, curdy precipitate, which is only slightly soluble 
in Avater, but dissolves easily in mineral acids, and in ace- 
tic acid. NICOTINE. 
279 
NICOTINE. 
§ 293. Nicotine may be separated from organic mix- 
tures by the process of Stas, but the operation is greatly 
facilitated by replacing the ether by chloroform, since 
nicotine is much more soluble in chloroform than in ether, 
under these circumstances. 
Like conine, nicotine is left in oily drops or streaks 
after the evaporation of its solution in chloroform or 
ether ; it has a pungent, suffocating odor, and an acrid, 
burning taste. It is soluble in all proportions of water, 
thus differing from conine, and is also soluble in alcohol, 
ether, chloroform, and benzol. 
Chemical tests.—If a watch-glass bearing a drop of 
hydrochloric acid be inverted over another glass contain- 
ing a drop of nicotine, the glasses become filled with 
white fumes, but these fumes are not as dense as those 
produced by conine, and no crystals of nicotine hydro- 
chloride are formed. In fact, the latter salt crystallizes 
with difficulty, and when pure nicotine is treated with 
aqueous hydrochloric acid, and the solution is allowed to 
evaporate, a syrupy liquid is obtained, without the forma- 
tion of crystals. 
Gold trichloride gives a yellow precipitate, somewhat 
darker in color than that produced with conine. 
Iodine in potassium iodide produces an amorphous pre- 
cipitate, varying from reddish-brown to yellow, accord- 
ing to the proportions of alkaloid and reagent present. 
Chlorine water produces no turbidity in aqueous solu- 
tions of nicotine. 
Tannin produces an abundant, white precipitate, which, 
when treated with hydrochloric acid, behaves like the 
precipitate produced by conine under the same circum- 
stances. 
Mercuric chloride throws down a white, curdy precipi- 
tate, which becomes yellow if much of the alkaloid be 
present, and at the same time groups of colorless crys- 
tals are deposited. If the solution of nicotine be dilute, 
the color of the precipitate does not change, but crystals 280 
DETECTION OF POISONS. 
are eventually deposited, as in the case of stronger solu- 
tions. 
These reactions are quite sufficient to distinguish nico- 
tine from conine,the only alkaloid with Avhich it is likely 
to be confounded in toxicological examinations. 
MORPHINE. 
§ 294. Opium and its principal alkaloid, morphine, are 
frequently employed criminally, and it sometimes becomes 
necessary to decide whether the latter alkaloid has been 
administered in a pure state as a salt, or whether poison- 
ing has been caused by one of the preparations of opium. 
In the latter case, it is sufficient that meconic acid, with 
which morphine is naturally combined in opium, be de- 
tected, together with the alkaloid; then, if sufficient of 
the poison be recovered, it may be possible to prove the 
presence of one or more of the other alkaloids which ex- 
ist in opium. 
The separation of morphine from organic mixtures is 
a matter of great difficulty, and none of the processes so 
far proposed yield very satisfactory results, especially 
when the alkaloid is to be sought in blood or in the solid 
tissues of the economy. Sometimes Stas’s method suc- 
ceeds very well, but if the agitation with ether and sub- 
sequent separation of the liquids be not conducted with 
great rapidity; or if, as sometimes occurs, the ether 
separate slowly from the aqueous liquid, all of the mor- 
phine will be deposited in the crystalline state, and none 
can be detected after the evaporation of the ether. No- 
thing is gained by the use of chloroform, for morphine is 
almost insoluble in that liquid. 
§ 295. To obviate this difficulty, Uslar and Erdmann 
suggested the use of hot amylic alcohol, in which mor- 
phine is quite soluble, and which separates readily from 
a watery liquid with which it has been agitated. 
The suspected mixture is diluted with water, if neces- 
sary, and acidulated with hydrochloric acid; it is then di- MORPHINE. 
281 
gested for several hours at a temperature of about 75°, on 
a water-bath, after which it is filtered through a cloth; the 
residue is again extracted with very dilute hydrochloric 
acid, and the extract, strongly pressed out, is added to 
the filtrate. The latter is then neutralized with ammonia, 
and evaporated to dryness on a water-bath. The residue 
is repeatedly extracted with hot amylic alcohol, and the 
solutions are united, and filtered through paper which 
has been previously moistened with amylic alcohol. The 
filtrate will contain fatty and coloring matters, together 
with morphine, should that alkaloid have been present in 
the original mixture. It is, therefore, agitated with three 
or four times its v’olume of hot water slightly acidulated 
with hydrochloric acid, and the alkaloid is thus converted 
into hydrochloride which is taken up by the water, while 
most of the other matters remain dissolved in the amylic 
alcohol. The latter is removed by the aid of a pipette, 
or a small separating funnel, and the aqueous liquid is 
repeatedly agitated with fresh portions of amylic alco- 
hol, until most of its color is removed. It is then evapo- 
rated to a small volume, neutralized with ammonia, and 
agitated with hot amylic alcohol. The latter takes up 
the free alkaloid ; after it has separated from the water 
it is carefully decanted, and the aqueous residue is again 
extracted with hot amylic alcohol. The alcoholic liquids 
are united, and evaporated to dryness on a water-bath. 
If the residue be dark-colored, it should be redissolved 
in very dilute hydrochloric acid, and the treatment with 
amylic alcohol repeated. However, it is often sufficiently 
pure for immediate examination, and, if amorphous, can 
be crystallized by dissolving it in a few drops of hot 
ordinary alcohol, and allowing the latter to evaporate 
spontaneously. 
§ 296. Another process for the separation of morphine 
has been proposed by Dr. T. G. Wormley, and is well 
adapted for the detection of the alkaloid when it is sus- 
pected that opium or one of its preparations has been 
administered. It depends upon the fact that a mixture of 
alcohol and ether dissolves morphine, to a certain extent, 
and at the same time separates without difficulty from 
an aqueous liquid with which it has been agitated. 282 
DETECTION OP POISONS. 
If the substance be a comparatively clear liquid, 
it is acidulated with acetic acid, evaporated to a small 
bulk on a water-bath, and filtered; if, however, the mix- 
ture be complex, the solids are divided as finely as 
possible, the mass is diluted, if necessary, with weak 
alcohol acidulated with acetic acid, and digested at a 
moderate temperature. The liquid is then strained 
through a cloth, and the residue is extracted with strong 
alcohol, and pressed, the washings being added to the 
filtrate. The latter is then evaporated to a small volume 
at a temperature of about 70°, and the residue is allowed 
to cool, and filtered through paper which has been moist- 
ened with water. An excess of lead acetate is added 
to the filtrate, and throws down any meconic acid that 
may be present, in the form of lead meconate; morphine 
and other opium alkaloids remain in solution. The 
precipitate is collected on a small, moistened filter, and 
washed with a little water, the washings being added to 
the filtrate. 
a) The precipitate may contain lead meconate; it is 
transferred to a test-tube by piercing the bottom of the 
filter while still moist, and washing its contents into the 
tube by a stream of distilled wrater from a wash-bottle. 
The lead compound suspended in the water is then de- 
composed by gaseous hydrogen sulphide, and the lead 
sulphide thrown down is separated by filtration. Any 
meconic acid present will be found in the filtrate, which 
is to be concentrated to a small volume on a water-bath. 
The residue, which will have a brownish color, if it con- 
tain much meconic acid, is distributed in several watch- 
glasses, and examined by the tests indicated in § 298. 
b) The filtrate is freed from the excess of lead acetate 
by gaseous hydrogen sulphide, and after the precipitate 
has subsided, the clear liquid is separated by filtration, 
and the filtrate evaporated to dryness on a water-bath. 
The residue is treated with a small quantity of water, 
and the liquid again filtered. The new filtrate is diluted, 
if necessary, rendered slightly alkaline by solution of 
potassium carbonate, and allowed to stand for a few 
moments. It is then agitated with several times its 
volume of anhydrous ether, to remove coloring matters CHEMICAL TESTS. 
and opium principles other than morphine, and the 
ethereal solution is decanted and set aside for subsequent 
examination, if necessary. 
The aqueous solution is now thoroughly agitated with 
four or five times its volume of a mixture of two parts of 
anhydrous ether with one part of pure alcohol; if the 
liquids do not separate readily after standing a few 
moments, their separation may be effected by the addition 
of a little pure ether. The layer of alcoholic-ether is 
decanted into a large watch-glass, and allowed to evapo- 
rate spontaneously, when the morphine will often be left 
in the crystalline form. The residue may be carefully 
washed by flowing a few drops of pure water over it, and 
will then be ready for chemical examination. 
Chemical Tests. 
§ 297. Concentrated nitric acid produces with mor- 
phine, or strong solution of its salts, a color varying from 
yellow to orange-red, according to the relative quantities 
of acid and alkaloid, and the dilution or concentration of 
the latter. The test succeeds best when a drop or two 
of the acid is placed upon the morphine or one of its salts 
in a dry state. 
Iodic acid is reduced hy morphine, iodine being set 
free; if, therefore, a strong solution of morphine or of 
one of its salts, or better, the alkaloid in the dry state, 
he treated with a drop or two of a concentrated solution 
of iodic acid, and a small quantity of starch paste be 
added, the characteristic blue color produced by free 
iodine and starch, will at once be developed. The re- 
duction is also made evident by the addition of ammonia, 
which changes the yellowish color of the liquid to yellow- 
ish-brown. The iodic acid solution may be conveniently 
replaced by sodium iodate, to which an excess of sul- 
phuric acid is added at the time of making the test. 
Solution of ferric chloride produces a blue color in 
neutral solutions of morphine or its salts. The intensity 
of the color depends upon the quantity of ferric chloride, 
of which the solution employed should be very dilute, 
MORPHINE. DETECTION OF POISONS. 
and the reaction succeeds best with the alkaloid or its 
salt in a dry state. The blue color is destroyed by acids, 
alkalies and heat; nitric acid changes it to orange-red. 
§ 298. When a solution of meconic acid is treated 
with a solution of a ferric salt, a blood-red color is 
developed, and this is unaffected by mercuric chloride 
or auric chloride, but is at once blackened by a solution 
of stannous chloride. This test is exceedingly delicate; 
a similar red color is produced by a ferric salt and an 
alkaline sulphocyanate, but this color disappears on the 
addition of mercuric chloride. Acetic acid also produces 
a red color with ferric salts, but acetic acid is not pre- 
cipitated by lead acetate, as is meconic acid. 
Lead acetate added to solutions of meconic acid, pro- 
duces a yellowish precipitate of lead meconate, which is 
insoluble in acetic acid. 
MECONIC ACID. 
OPIUM ALKALOIDS OTHER THAN MORPHINE. 
§ 299. Besides morphine, opium contains other alka- 
loids, of which the more important are codeine or methyl- 
morphine, and narcotine. In the processof T. G.Wormley 
these ai*e removed from the alkaline aqueous solution 
when it is agitated with ether to decolorize the liquid. 
The most sensitive test for codeine is iodized potassium 
iodide ; this reagent, having a pale yellow color, strikes 
a violet-red color with codeine. The latter alkaloid does 
not reduce iodic acid, nor does it produce any coloration 
with ferric chloride. Sulphuric acid gives a blue color. 
Narcotine yields a red color when heated with con- 
centrated sulphuric acid, and this changes to a violet 
when the dry residue is moistened with nitric acid. A 
little narcotine moistened with sulphuric acid, or a solu- 
tion of narcotine treated with strong sulphuric acid, ac- 
quires a red color after standing for twenty-four hours, 
without the aid of heat. STRYCHNINE. 
285 
STRYCHNINE. 
§ 300. Strychnine is almost insoluble in ether ; hence 
the method of Stas is not applicable to the separation of 
this alkaloid from organic mixtures. If, however, the 
ether be replaced by chloroform (Rodger and Gfirdwood’s 
process), all of the alkaloid may be separated, for one 
part of strychnine only requires about eight parts of 
chloroform for its solution. Consequently, when the 
presence of strychnine is suspected, the aqueous solution 
which has been rendered acid by tartaric or acetic acid, 
is neutralized Avith potassium or sodium carbonate, and 
agitated Avith about an equal volume of pure chloroform; 
after the liquids have separated, the heavy chloroformic 
layer is remoAred, either by decanting off the upper layer 
or by the aid of a separating funnel, and is alloAved to 
evaporate spontaneously. The residue may present 
crystals of strychnine; generally, hoAveArer, in order to 
eliminate all foreign organic matter, the dry residue 
must be dissolved in a little distilled Avater containing a 
drop or tAVO of acetic acid ; the solution is filtered, neu- 
tralized with potassium or sodium hydrate, and again 
extracted by chloroform. The alkaloid is usually ob- 
tained in a crystalline form after the spontaneous evapor- 
ation of this second solution, and the chemical tests may 
be applied immediately. 
CHEMICAL TESTS. 
§ 301. Potassium and sodium hydrates and ammonia, 
produce in solutions of strychnine salts a white amor- 
phous precipitate, consisting of the free alkaloid which 
soon assumes a crystalline form. Strychnine and all of 
its salts are peculiarly bitter, and the taste is used as 
confirmatory evidence to the chemical reactions. 
When strychnine or one of its salts is treated with a 
little concentrated sulphuric acid, and potassium dichro- 
mate is added, a characteristic play of colors is mani- 
fested, a blue tint first appearing, which soon changes 286 
DETECTION OF POISONS. 
to violet and red, and ultimately the color disappears 
altogether. 
The test may be made in a porcelain capsule or in a 
watch-glass, and is best applied to the suspected sub- 
stance in a solid state. The latter is moistened with a 
drop of concentrated sulphuric acid, in which the pure 
alkaloid will dissolve without change of color; a minute 
fragment of potassium dichromate is then placed in the 
drop of liquid, and moved around by the aid of a slender 
glass rod. If strychnine be present, a blue color is at 
once produced, and rapidly changes to violet and red,— 
then fades entirely. This test is exceedingly delicate 
and characteristic, but it may entirely fail if morphine 
be present. When, however, chloroform is used in the 
extraction of the alkaloid, or even when ether is used 
and the alkaline aqueous liquid is allowed to stand for 
some time before extracting it with ether, morphine can- 
not possibly be present. Sometimes the presence of cer- 
tain organic substances which may be removed by chlo- 
roform from complex mixtures, interferes with this test. 
If a negative result be obtained, it is therefore advisable 
to add a trace of strychnine to a separate portion of the 
chloroform extract, and to test this in the usual manner; 
if this portion then respond to the color test, while no 
result can be obtained from the extract to which no 
strychnine was added, the absence of strychnine may be 
safely inferred. 
Solution of potassium dichromate produces, in solu- 
tions of strychnine and its salts, a bright yellow crystal- 
line precipitate of strychnine chromate. After removing 
the excess of liquid by careful decantation, or by means 
of a piece of filter-paper, this precipitate may be dried, 
and then moistened with a drop or two of concentrated 
sulphuric acid ; a rich blue color will then be developed, 
changing to purple, violet, and red. By making the 
potassium dichromate test first, the color reaction may 
thus be afterwards tried upon the same portion of the 
suspected substance. BRUCINE. 
287 
BRUCINE. 
§ 302. Brucine is separated from organic mixtures by 
the same process which serves for the separation of 
strychnine. It is soluble in almost all proportions of 
chloroform, and is also freely soluble in alcohol. 
The residue left after the evaporation of its solutions 
may be identified as brucine by the following tests: — 
Brucine immediately assumes a blood-red color when 
moistened with a drop of concentrated nitric acid, and 
dissolves, forming a red solution. If this solution be 
heated, its color changes from red to orange or yellow ; 
if now it be allowed to cool, and a drop of stannous 
chloride solution be added, a purple color is developed, 
but soon disappears if either the nitric acid or stannous 
chloride be employed in considerable excess. 
Brucine dissolves in concentrated sulphuric acid, form- 
ing a rose-red solution ; if a minute crystal of potassium 
dichromate be added to the mixture, an orange or brown 
color is produced, and gradually changes to green, 
chromic oxide being precipitated. Brucine may thus be 
readily distinguished from strychnine. 
If a small crystal of potassium nitrate be added to the 
pale red solution of brucine in concentrated sulphuric 
acid, the liquid assumes an orange-red color. 
A determination of the physiological action of the sub- 
stance, supposed to be an alkaloid, which may be ex- 
tracted from the contents of the stomach, etc., is often of 
great value in the selection of the chemical tests. This 
is especially the case with strychnine and brucine. A 
very small quantity of the substance is required for the 
test, and the experiment may easily be made upon a frog 
or rabbit. Some poisons, such as digitaline, absolutely 
require that the physiological test shall be made for their 
certain identification. 
PHYSIOLOGICAL TEST. 288 
DETECTION OF POISONS. 
DETECTION OF ALCOHOL IN ORGANIC 
MIXTURES. 
§ 803. In cases where alcohol has been taken shortly 
before death, it may generally be detected in the con- 
tents of the stomach ; the odor of the alcoholic prepara- 
tion is often perceptible in such mixtures. 
It is necessary, however, to separate the alcohol in a 
state of approximate purity. If the organic matter be 
viscous, it is diluted with water, but if quite fluid the 
dilution is unnecessary. It is exactly neutralized by 
potassium carbonate, should its reaction be acid, and is 
distilled on a water-bath, in a flask or retort connected 
with a good condensing apparatus. When about one- 
sixth of the liquid has passed over, the distillate is ex- 
amined as follows:— 
If it contain alcohol, it will usually have the peculiar 
odor of the alcoholic preparation from which it has been 
derived. 
Its specific gravity will be less than that of water. 
When mixed with dilute sulphuric acid and a few 
drops of potassium dichromate solution, the liquid be- 
comes green, owing to the separation of chromic oxide ; 
the odor of aldehyde may at the same time be observed. 
This reaction is not characteristic, but may serve to con- 
firm other tests. If dilute alcohol be shaken up with an 
excess of solid and dry potassium carbonate in a test-tube, 
the greater part of the water will be taken up by the 
potassium carbonate, and two layers of liquid will be 
formed. The alcohol constitutes the upper layer, and 
will burn on the application of flame. Before agitating 
the dilute alcohol with potassium carbonate, it should be 
purified as much as possible by repeated rectification, 
only about one-half of the liquid being collected at each 
distillation. 
By the aid of any good fractionating apparatus, small 
traces of alcohol may be separated from the urine without 
difficulty, after the ingestion of alcoholic liquids. GENERAL PROCESS FOR ALL POISONS. 
289 
CHEMICAL EXAMINATION FOR THE DETEC- 
TION OF A POISON OF WHICH THE 
NATURE IS NOT KNOWN. 
§ 304. As a rule, in toxicological examinations, some 
index is afforded to the nature of the poison present, 
before the chemical analysis is undertaken. Sometimes 
this index is furnished by a physical examination of the 
suspected substance ; thus, if hydrocyanic acid, phos- 
phorus, alcohol, chloroform, nitrobenzol, or other volatile 
poison be present, the characteristic odor of the matter 
generally guides the chemist to a certain extent in his 
selection of methods. The seeds of certain plants, stra- 
monium, for example, or solid particles, such as arsenious 
oxide, may also indicate the probable poison to which 
particular attention must be directed. 
Sometimes, however, none of these evidences are pre- 
sent, and the chemist is required to make an examination 
that shall include the whole range of poison that can be 
detected. 
§ 305. Thesuspected mixture,rendered as homogeneous 
as possible by finely dividing the solid portions, is intro- 
duced into a large flask or retort, and distilled in a dark 
room. Phosphorus will show itself, if present, by a 
phosphorescent glow which fills the tube and the upper 
part of the condenser (§ 286). The condensed liquid 
is examined for hydrocyanic acid, as directed in § 284, 
and for alcohol, or any other volatile liquid, whose pre- 
sence may be indicated by its peculiar odor. 
The distillation must not be continued to dryness, nor 
must the temperature be allowed to rise above 100°, 
otherwise certain vegetable poisons might be destroyed. 
Volatile Poisons. 
Alkaloids. 
§ 306. The contents of the retort are removed, and 
treated with alcohol and the required amount of tartaric 290 
DETECTION OF POISONS. 
acid, and any alkaloids present are separated by the 
process of Stas (§ 290). However, after the final ex- 
traction of the alkaline aqueous solution Avith ether, the 
same operation should be repeated, the ether being re- 
placed by chloroform (strychnine, brucine) ; and finally, 
after decanting the chloroform, the aqueous liquid should 
be agitated with hot amylic alcohol or with alcoholic- 
ether (morphine). 
The folloAving compounds pass from the acid aqueous 
solution into the ether Avith Avhich it is agitated to re- 
move coloring matter (§ 290):— 
Colchicine (partly). Digitaline. Pierotoxine. 
The folloAving alkaloids pass into the ether from the 
alkaline aqueous solution:— 
Nicotine. 
Narcotine. 
Aconitine. 
Conine. 
Brucine (partly). 
Atropine. 
Veratrine. 
Strychnine (partly). 
Colchicine (partly). 
The agitation with chloroform removes the remainder 
of any strychnine or brucine that may be present, while 
morphine remains in the alkaline liquid in which it Avas 
precipitated, and is extracted, as above indicated, either 
by alcoholic ether, or by hot amylic alcohol. The tests 
for these alkaloids are made upon the residues left after 
the evaporation of the ethereal, chloroformic, or amylic 
extracts ; the properties by which the more commonly 
occurring alkaloids may be recognized, have already been 
described. 
The aqueous residue left after the operations for the 
extraction of the alkaloids, may contain oxalic acid ; a 
portion of it should therefore be tested as directed in 
§ 280. 
Metallic Poisons. 
§ 307. The remainder of the aqueous mixture, to- 
gether with the solid residue which was extracted by 
alcohol and tartaric acid, is mixed with hydrochloric 
acid, and may be directly tested by Reinsch’s test for 
arsenic, antimony, and mercury. Whether the result he 
affirmative or negative, the mixture is heated on a water- 
bath, and powdered potassium chlorate is gradually METALLIC POISONS. 
291 
added until all of the solid matter is disintegrated and 
the liquid is fit for filtration. The liquid, which should 
be filtered hot, may contain the following metals:— 
Arsenic as arsenic acid. 
Antimony as antimony trichloride. If the presence 
of antimony be suspected, the digestion and treatment 
with potassium chlorate should be made in a retort, be- 
cause antimony chloride may be lost by volatilization, if 
the mixture be heated in the open air. In this case, the 
liquid which distils from the retort must also be examined 
for antimony. 
Tin as stannic chloride. The operation should be 
conducted in a retort, as in the case of antimony. 
Mercury as mercuric chloride. 
Lead as lead chloride : this may separate in crystal- 
line plate from the filtrate as the latter cools. 
Copper as cupric chloride. 
Bismuth as trichloride; this forms a white precipitate 
on the addition of water, bismuth oxychloride being 
thrown down. 
Zinc as chloride. 
For the detection of any of these metals that may be 
present, the filtrate is saturated with hydrogen sulphide. 
Yellow precipitates are formed by arsenic, tin, and 
cadmium. 
An orange-colored precipitate by antimony. 
Brownish-black by bismuth. 
Black by mercury, silver, copper, and lead. If the 
liquid be not completely saturated with hydrogen sul- 
phide, lead will be precipitated as sulpho-chloride, which 
is red or brownish. 
After filtration from any precipitate formed by the 
hydrogen-sulphide, the liquid is partially neutralized 
with ammonia; this is best accomplished by removing a 
small portion of the liquid, completely neutralizing the 
remainder, and then again mixing the two portions. 
Sufficient sodium acetate is then added to replace all of 
the free hydrochloric acid by acetic acid, and the liquid 
is again saturated with hydrogen sulphide. Any zinc 
present will be precipitated as zinc sulphide. 
These metallic sulphides are subsequently treated as has 292 
DETECTION OF POISONS. 
been directed, for the identification of the different metals 
individually. 
The residue left on the filter may contain silver or 
lead in the form of chloride. It is dried, strongly cal- 
cined with sodium carbonate and sodium nitrate, and the 
fused mass is dissolved in water, and examined for small 
globules of metal. 
The liquid from which zinc may or may not have been 
precipitated by hydrogen sulphide, is boiled to expel 
hydrogen sulphide, rendered strongly acid with hydro- 
chloric acid, and sulphuric acid is added. A white 
precipitate indicates the presence of barium ; this precipi- 
tate is collected, and the presence of barium confirmed 
by appropriate tests. APPENDIX. 
VOLUMETRIC ANALYSIS. 
1. The principles of volumetric analysis, of which 
numerous examples have been given in this work, are of 
almost universal application. 
The solutions which are usually employed in the analy- 
sis of urine and in other clinical analyses, are standard 
solutions, so graduated that the calculation of the results 
may be as little complicated as possible. They are 
usually made so that each cubic centimetre shall repre- 
sent 5 or 10 milligrammes of the substance to be esti- 
mated. 
In general analysis, normal and decinormal solutions 
are employed, these names being applied to solutions 
which are volume for volume equivalent to each other. 
Such solutions may evidently be made by dissolving 
equivalent proportions of the respective substances in 
one litre of water ; for instance, a litre of normal hydro- 
chloric acid, containing 36.5 grammes of the acid, and 
a litre of normal sodium hydrate, containing 40 grammes 
of the latter compound, would reciprocally neutralize 
each other, 36.5 being the molecular weight of hydro- 
chloric acid and 40 being the molecular weight of sodium 
hydrate, and these two substances reacting upon each 
other molecule for molecule. Then, of compounds such 
as sodium hydrate and hydrochloric acid, normal solu- 
tions are made by dissolving in water a quantity of the 
compound equal to its molecular weight expressed in 
grammes, and diluting the liquid to exactly one litre. 
One molecule of sulphuric acid will react with and 
neutralize two molecules of sodium hydrate, hence one 
litre of normal sulphuric acid, which must he equivalent 294 
APPENDIX. 
to one litre of normal sodium hydrate, must contain, not 
98 grammes of sulphuric acid, 98 being the molecular 
weight of IPSO4, but 49 grammes, or half the molecu- 
lar weight expressed in grammes. 
Decinormal solutions are of exactly one-tenth the 
force of normal solutions, and are usually made by 
diluting 100 c. c. of the corresponding normal solution 
to one litre. 
When one normal solution has been prepared of exact 
strength, the others may readily be made. A convenient 
solution to prepare first is that of sodium carbonate ; 
the molecular weight of this substance, perfectly pure 
and dry, is 106 ; since its molecule contains two atoms 
of sodium, 53 grammes of pure sodium carbonate are 
dissolved in water, and the solution is diluted to one litre. 
Each cubic centimetre of this solution contains 53 milli- 
grammes of the salt. 
Normal sulphuric acid may then be made by diluting 
49 grammes of pure concentrated sulphuric acid to about 
950 cubic centimetres. This solution is not exact, and 
must be titrated with the normal sodium carbonate. A 
burette is filled to the zero line with the normal acid, and 
a convenient quantity, say 20 c.c., of the sodium car- 
bonate solution is measured into a beaker, and enough 
litmus solution is added to communicate a pale-blue color 
to the liquid. It is then necessary to determine how 
much of the acid solution is required to neutralize the 
sodium carbonate, as indicated by the change of color of 
the liquid; if the acid were exactly normal, 20 c.c. 
should be required. Since carbonic acid is set free, and 
is in part absorbed by the liquid, the litmus would be 
reddened too soon if the carbon dioxide Avere not ex- 
pelled, for carbonic acid itself will redden litmus. There- 
fore the liquid is heated to boiling before adding the 
acid from the burette, and the sulphuric acid is then 
allowed to floAV in, with constant stirring, until the color 
of the liquid changes. The solution is again boiled, and 
the blue color Avill probably return; more acid is then 
added until the red color becomes permanent. It must 
be remembered that it is a change of color, and not an PREPARATION OF NORMAL SOLUTIONS. 
295 
intensity of tint, that indicates the termination of the 
experiment. 
The quantity of the sulphuric acid used must have 
contained 980 milligrammes of sulphuric acid, for it has 
exactly neutralized 20 c.c. of a solution of sodium car- 
bonate, of which each cubic centimetre contained 53 
milligrammes. As the acid was somewhat stronger than 
required, less than 20 c. c. will have been employed; 
suppose 19.2 c.c. were actually used; then for every 
19.2 c. c., 0.8 c. c. of water should be added. The exact 
volume of the dilute acid remaining is therefore ascer- 
tained, and 0.8 c. c. of water are added for every 19.2 
c. c. of solution. The acid, which should now be exactly 
normal, is again titrated with normal sodium carbonate 
as before, in order that its accuracy may be verified. 
With these two normal solutions, all other normal 
solutions of alkaline or acid compounds may be prepared. 
For instance, 40 grammes of sodium hydrate are dis- 
solved in 900 c. c. of water, and the solution is titrated 
with the normal sulphuric acid, and diluted so that the 
two liquids shall be equivalent, volume for volume. It 
is not necessary to heat the liquid in this case, nor in 
any other acidimetric or alkalimetric titration in which 
no carbonic acid is liberated. 
NORMAL SODIUM CARBONATE. 1 LITRE = 53 GRAMMES 
Na2C03. 
Preparation of Normal Solutions. 
2. It is not always easy to procure chemically pure 
sodium carbonate, but pure sodium acid-carbonate may 
always be obtained, and is indeed preferable for the 
preparation of this solution. 85 grammes of sodium acid 
carbonate are heated to incipient redness in a platinum 
or porcelain dish, and when the salt is entirely reduced 
to the neutral carbonate, which will require ten or fifteen 
minutes, it is allowed to cool in a desiccator. When 
cold, the residue is rapidly weighed, the small quantity 
in excess of 53 grammes is removed, and the residue 
dissolved in distilled water. The solution, with the 
washings of the dish in which the carbonate was heated 296 
APPENDIX. 
and of that in which the solution was effected, is intro- 
duced into a litre flask, and diluted to exactly one litre 
with distilled water. 
NORMAL SULPHURIC ACID. 1 LITRE = 49 GRAMMES 
H2S04. 
3. The preparation of this solution has already been 
described; it must be titrated with the normal sodium 
carbonate, and diluted to exactly the required strength. 
NORMAL NITRIC ACID. 1 LITRE = 63 GRAMMES IINO3. 
4. Normal nitric acid must be used instead of normal 
sulphuric acid when calcium, strontium, or barium hy- 
drates or carbonates, are to be dissolved, since the sul- 
phates of these metals are insoluble. The solution is 
made by diluting about 50 cubic centimetres of pure 
concentrated nitric acid, with distilled water, to about 
950 c.c., and titrating the liquid with normal sodium 
carbonate and correcting it, precisely as has been directed 
for the preparation of the normal sulphuric acid. 
NORMAL SODIUM HYDRATE. 1 LITRE = 40 GRAMMES 
NaOII. 
5. The sodium hydrate employed must be quite pure, 
and free from carbonate. A*s it cannot be obtained 
absolutely dry, it is necessary to dissolve rather more 
than the required quantity in order to make one litre of 
the solution; 42 or 43 grammes are dissolved in 800 or 
900 c.c. of water, and when cold the solution is titrated 
with the normal sulphuric acid, as already indicated, and 
diluted as found necessary. This solution must be pre- 
served in well-stoppered bottles, that it may not absorb 
carbon dioxide from the air. 
6. With these acid and alkaline normal solutions and the 
corresponding decinormal solutions, it is only possible to 
estimate directly the amount of free acid, alkali or 
line carbonate in any given liquid, the nature of the ESTIMATION OF CARBONIC ACID GAS. 
297 
substance to be estimated of course being known; but 
by indirect processes, these same solutions may serve for 
the estimation of a great number of substances, and are 
of almost unlimited application. 
The estimation of the acidity of the urine by means of 
decinormal sodium hydrate, has already been explained 
(§ 128). 
The examples which follow are such as require but 
little apparatus, and will serve to illustrate the applica- 
tion of acidimetry and alkalimetry. 
ESTIMATION OF CARBONIC ACID GAS, FREE AND COMBINED, 
IN WATER. 
7. This method depends upon the precipitation of 
harium carbonate by the action of carbonic acid on baryta 
water, and upon the decomposition of alkaline carbonates 
Avhen boiled with baryta water, the same precipitation 
taking place. The exact strength of the baryta water is 
first found by titration with decinormal nitric acid, and 
the solution must then be preserved out of contact with 
the air. 
A measured volume of the water (200-500 c.c.) is 
boiled with a slight excess of the baryta-water, exactly 
measured, in a flask, and the latter is corked and allowed 
to cool. About half of the clear liquid is then decanted 
or transferred by the aid of a pipette into a beaker, and 
the excess of barium hydrate is exactly titrated with 
decinormal nitric acid. As the decomposition of any 
alkaline carbonate present will have introduced into the 
solution a quantity of alkaline hydrate exactly equiva- 
lent to that of the barium hydrate which effects such de- 
composition, the difference between the volume of deci- 
normal acid required and that which would have been 
used had the alkalinity of the barium solution not been 
disturbed, will correspond to the free carbonic acid pre- 
sent, together with half of that which existed in combina- 
tion as acid carbonates. 
The precipitate in the flask is then collected on a filter, 
thoroughly washed with boiling water, and filter and 
precipitate together are placed in a .beaker and treated 
with an exactly measured volume of decinormal nitric 298 
APPENDIX. 
acid. The excess of the latter is then estimated by deci- 
normal sodium hydrate ; the difference indicates the total 
amount of carbonic acid present in the water, all having 
been precipitated as barium carbonate. 
Example.—250 c.c. of mineral water are boiled with 
50 c.c. of baryta-water, which has been found by pre- 
vious tritation to be exactly equivalent to 56 c.c. of deci- 
normal nitric acid. After cooling, 150 c. c. of the liquid 
(the total volume after mixing was 300 c. c.) are found 
to require 9.3 c.c. of decinormal nitric acid for perfect 
neutralization, as indicated by either litmus solution or 
turmeric paper; the-300 c.c. Avould therefore have re- 
quired 18.6 c.c.; and the difference between this and 
56 c.c. = 37.4 c.c., expresses in nitric acid the quantity 
of free carbonic acid in the water, and half of that which 
existed as acid carbonates. But each cubic centimetre 
of decinormal nitric acid contains 6.3 milligrammes of 
nitric acid, and this is equivalent to 2.2 milligrammes of 
carbonic acid gas; therefore 37.4x2.2= 82.28 milli- 
grammes of carbon dioxide were contained, free and as 
acid carbonates, in the 250 c.c. of water analyzed. 
The precipitate is collected, washed, and dissolved in 
50 c. c. of decinormal nitric acid, and the excess of acid 
is estimated by decinormal sodium hydrate, of which 6.1 
c.c. are required. Since the acid and alkali are equiva- 
lent to each other, volume for volume, 43.9 c.c. of the 
nitric acid were neutralized in dissolving the barium car- 
bonate, and correspond to an equivalent quantity of car- 
bon dioxide which was disengaged. Therefore the total 
carbonic acid of the 250 c.c. of water = 2.2x 43.9 = 
96.58 milligrammes. The difference 96.58 — 82.28 = 
14.30 milligrammes may be formulated as that Avhicli 
exists in combination ; but as solutions containing free 
carbonic acid do not contain carbonates, but acid car- 
bonates, containing double the proportion of acid con- 
tained in the neutral salts, it is more correct to divide 
the carbon dioxide between acid carbonates and free 
carbonic acid. Thus— 
As acid carbonate ..... 0.0286 
As free acid ...... 0.0680 
Total CO2 0.0966 ESTIMATION OF ACID IN NEUTRAL SALTS. 
299 
8. In solutions of ammoniacal salts, the ammonia may 
be estimated by a very simple process, provided the solu- 
tion be neutral. If it be acid or alkaline, it must be ex- 
actly neutralized. It is then boiled with an excess of 
normal or decinormal sodium hydrate, until all of the 
ammonia is expelled, and the excess of alkali is estimated 
by normal nitric acid. 
Example.—100 c. c. of an ammoniacal liquid are ex- 
actly neutralized, and boiled with 20 c.c. of normal 
sodium hydrate until the vapors disengaged no longer 
have any action on red litmus paper. The liquid is then 
titrated with normal sulphuric acid, of which it is found 
that just 13.7 c.c. are required to effect neutralization ; 
6.3 c.c. of sodium hydrate have therefore been used in 
decomposing the ammoniacal salt; but each cubic centi- 
metre contained 40 milligrammes of sodium hydrate, which 
would expel 17 milligrammes of ammonia. The 100 c.c. 
of liquid analyzed therefore contained 17 X 6.3 = 0.1071 
gr. of ammonia. 
ESTIMATION OF AMMONIA. 
ESTIMATION OF COMBINED ACID IN NEUTRAL SALTS. 
9. This method is only applicable when the salt is 
entirely decomposed by an excess of an alkaline hydrate 
or carbonate, a metallic hydrate or carbonate being pre- 
cipitated. 
A weighed quantity of the salt, or a measured volume 
of its solution, should it be in solution, is treated with 
an excess of normal sodium hydrate or sodium carbonate, 
as may be required ; the mixture is then diluted to a 
known volume, and the excess of alkali is estimated in 
the clear liquid after the precipitate has subsided. 
Example.—It is required to estimate the proportion 
of chlorine in a solution of barium chloride, or in the dry 
salt. In the latter case, one or two grammes of the salt 
are dissolved in water, 20 c. c. of normal sodium carbon- 
ate are added, and the liquid is diluted to say 200 c.c.; 
if the salt be in solution, 50 or 100 c.c. are treated with 
20 c.c. of normal sodium carbonate, and the whole is 300 
APPENDIX. 
diluted to 200 c. c. as before. After the precipitate has 
subsided, 100 c. c. of the clear liquid are removed, 
placed in a beaker, and titrated with normal nitric acid. 
Suppose 2.1 c.c. of the latter be required: then, since 
only half of the liquid is operated upon, 4.2 c.c. Avould 
be required by the 200 c.c., each of which has neutral- 
ized one cubic centimetre of sodium carbonate. There- 
fore 20 — 4.2 = 15.8 c.c. of normal sodium carbonate 
were used in precipitating the barium salt, and, since 
each c.c. contains 40 milligrammes of sodium hydrate, it 
corresponds to 35.5 milligrammes of chlorine. Then the 
quantity of BaCl2 under analysis contained 35.5 X 15.8 
= 0.4609 gr. of chlorine. 
Of course the acid of any other soluble barium salt 
could be estimated in the same manner, and the method 
is capable of very extended application. 
10. The estimation of chlorine in urine by means of a 
standard solution of silver nitrate is described in § 153. 
In general analysis, a normal and a decinormal solution 
of silver nitrate, containing respectively 17 0 grammes and 
17 grammes of the salt per litre, are used instead of the 
standard solution. 
11. The estimation of iron volumetrically by means of 
potassium permanganate, has been given in section 182, 
on the estimation of hemoglobin in blood. 
12. For the sake of convenience in the calculation of 
analyses, the solutions employed in the volumetric analy- 
sis of urine are so made that each cubic centimetre may 
represent either five or ten milligrammes of the substance 
to be estimated : the volumes of urine analyzed are then 
so selected that the number of cubic centimetres of stand- 
ard solution used, represents either the number of grammes 
of the substance contained in one litre of urine, or a deci- 
mal fraction of that quantity. 
Thus 1 c.c. of the solution of mercuric nitrate, used 
STANDARD SOLUTIONS. STANDARD SOLUTIONS. 
301 
for the estimation of urea (§ 147), corresponds to 0.010 
gr. of urea. In this method 10 c. c. of urine are 
analyzed ; should these require 10 c. c. of mercury solu- 
tion, one litre of urine would evidently contain 10 gr. of 
urea. The number of cubic centimetres used, therefore, 
corresponds to the number of grammes of urea in one 
litre of urine. 
In the preparation of the mercuric nitrate solution, 
of which one litre must precipitate 10 grammes of urea 
as a compound of one molecule of urea nitrate with 
two molecules of mercuric oxide, somewhat more than 
the calculated quantity of mercuric oxide must be used 
in order to produce the final reaction with the sodium 
carbonate. The quantity required by the formula 
CON2H4 -f 2HgO, would he i^*1Q = 72 gr. per 
litre, 60 being the molecular weight of urea, and 216 
that of mercuric oxide. It is found that a sufficient ex- 
cess of mercuric oxide is present if 77.2 gr. (correspond- 
ing to 96.855 gr. of mercuric chloride, in which form the 
mercury is best weighed), be employed. One litre there- 
fore contains 5.2 gr. of mercuric oxide in excess of that 
absolutely required for 10 gr. of urea. It has been 
mentioned (page 109) that this estimation is only exact 
when 100 c. c. of the liquid analyzed contain two grammes 
of urea: the reason is obvious, for the solution is stan- 
dardized by a two per cent, solution of urea ; 15 c. c. of 
the latter would require 80 c. c. of mercuric nitrate, con- 
taining 5.2 x 30=156 milligrammes of mercuric oxide in 
excess, which would exist in 45 c. c. of liquid. Each c.c. 
would therefore contain 3.47 milligrammes of mercuric 
oxide to react with the sodium carbonate. Suppose the 
15 c.c. to contain twice as much urea as before: then 
60 c. c. of mercury solution would be required, and 75 
c. c. of the mixture would contain 60x5.2=312 milli- 
grammes of mercuric oxide to react with the sodium car- 
bonate, that is, each c.c. would contain 4.16milligrammes, 
or 0.69 milli. more than in the former case. It is evi- 
dent that the reaction with sodium carbonate wrould then 
take place too soon, and the liquid would contain more 
26 302 
APPENDIX. 
urea than indicated by the analysis, unless it were prop- 
erly diluted. 
In the method for the estimation of sodium chloride 
(§ 153), exactly the quantity of fused silver nitrate re- 
quired to react with 10 grammes of sodium chloride, is 
dissolved in one litre of water, 
58.5 : 10 : : 170 : x, 
58.5 being the molecular weight of sodium chloride, 
and 170 that of silver nitrate. The number of cubic 
centimetres of the silver solution required by the resi- 
due of 10 c. c. of urine, represents the number of 
grammes of sodium chloride in one litre of urine. 
The uranium solution for the estimation of phosphoric 
acid (§ 154), only gives accurate results when the analy- 
ses are made under the same conditions as the titration 
of the standard solution. Since 50 c. c. of urine are 
analyzed, the force of the uranium solution (1 c. c. = 
0.005 gr. P20:5) has the convenience that one-tenth the 
number of centimetres used expresses the number of 
grammes of phosphoric anhydride in one litre of urine. 
Thus if 18 c. c. of the uranium solution be required to 
precipitate 50 c. c. of urine, one litre of the latter will 
contain 1.8 gr. of phosphoric anhydride. WEIGHTS AND MEASURES. 
303 
Grains. 
Ounces Troy 
= 480 grains. 
Pounds 
Avoirdupois. 
1 Milligramme = 
0.01543 
0.000032 
0.0000022 
1 Centigramme= 
0.15432 
0.000321 
0.0000220 
1 Decigramme = 
1.54323 
0.003215 
0.0002204 
1 Gramme = 
15.43234 
0.032150 
0.0022046 
1 Decagramme = 
154.32349 
0.321507 
0.0220462 
1 Hectogramme = 
1543.23488 
3.215072 
0.2204621 
1 Kilogramme = 
15432.34880 
32.150726 
2.2046212 
Weights and Measures. 
1 Grain = 0.064799 grammes. 
1 Oz. Troy = 31.103496 grammes. 
1 lb. avoirdupois = 0.453495 kilogrammes. 
1 oz. avoirdupois = 28.343437 grammes. 
To convert centigrade degrees into Fahrenheit degrees, 
multiply by 9, divide the product by 5, and add 32°. 
To convertFahrenheit degrees into centigrade degrees, 
subtract 32°, then multiply by 5 and divide by 9. 
1 Metre = 39.370708 inches. 
1 Centimetre = 0.393707 “ 
1 Millimetre = 0.039370 “ 
1 inch = 2.539954 centimetres. INDEX. 
ACID, acetic, 18 
benzoic, 25 
butyric, 18 
capric, 18 
caproic, 18 
caprylic, 18 
cholic, 58 
formic, 17 
glycocholic, 56 
hippuric. 37 
estimation in urine, 115 
liydracrylic, 21 
hydrochloric, detection, in 
cases of poisoning, 265 
estimation, in gastric juice, 
191 
hydrocyanic, detection in 
cases of poisoning, 269 
detection in solution, 271 
in vapor, 269 
estimation, 272 
tests for, 270, 271 
lactic, 20 
meconic, detection in cases of 
poisoning, 282, 284 
nitric, detection in cases of 
poisoning, 266 
oxalic, 22 
detection in cases of poison- 
ing, 268 
estimation, 269 
oxaluric, 45 
paralactic, 21 
phosphoglyceric, 59 
propionic, 18 
succinic, 24 
detection in urine, 25 
sulphuric,. detection in cases 
of poisoning, 264 
estimation in ashes, 224 
in urine, 121 
taurocholic, 57 
uric, 39 
Acid, uric— 
estimation, 114 
valeric. 18 
Acids, biliary, 56-58 
detection in blood, 145 
in urine, 97 
Pettenkofer’s test for, 56, 97 
fatty, 17 
detection and separation, 19 
mineral, detection in cases of 
poisoning, 262 
detection in stains on cloth- 
ing, 267 
estimation in neutral salts, 
299 
Albumen, 65 
detection in urine, 94 
estimation, 66 
estimation in blood, 122 
in serous liquids, 168 
in urine, 122 
Albumen of white of egg, 66 
Albuminoid bodies, 61 
classification of, 64 
detection of, 63 
general properties, 62 
Albuminose, 73 
Alcohol, detection in complex 
mixtures, 288 
Alkaloids, detection in cases of 
poisoning, 275 
general reagents for, 277 
physiological test for, 287 
separation from organic mix- 
tures, 275 
Ammonia, detection in blood, 
145 
in urine, 93 
estimation in urine, 125 
volumetric estimation of, 299 
Ammonium urate calculi, 136 
sediment, 133 
Analysis, volumetric, 293 INDEX. 
Animal ferments, 74 
pigments, 78 
Antimony, detection in cases of 
poisoning, 244 
quantitative estimation, 247 
separation from arsenic, 246 
tests for, 244 
Arsenic, detection in cases of 
poisoning, 229 
electrolytic test, 241 
Marsh’s test, 237 
ordinary compounds of, 229 
quantitative estimation, 243 
Reinsch’s test, 236 
separation from organic mix- 
tures, 235 
trisulphide, 229 
Arsenical pigments in paper- 
hangings, 235 
Arsenious oxide, 230 
liquid tests for, 232 
reduction test, 231 
sublimation test, 230 
Ashes of animal substances, 219 
estimation of calcium, 224 
of chlorine, 225 
of iron phosphate, 223 
of phosphoric acid, 225 
of potassium and sodium, 
223 
of sulphuric acid, 224 
qualitative analysis of, 219 
quantitative analysis of, 223 
BARIUM, detection in cases of 
poisoning, 292 
Bile, general properties of, 193 
Biliary calculi, 194 
pigipents, 79 
detection in urine, 98 
in blood, 145 
Gmelin’s test for, 80 
Bilifuscin, 81 
Biliprasin, 81 
Bilirubin, 79 
Biliverdin, 80 
Bismuth, detection in cases of 
poisoning, 291 
Blood, 140 
abnormal constituents, 140 
analysis of, 143 
anatomy of, 140, 158 
Blood— 
calculation of analyses, 148, 
152 
corpuscles, 159 
detection of ammonia in, 145 
of biliary matter, 145 
of carbon monoxide, 146 
of creatine and creatinine, 
144 
of glucose, 144 
of mineral salts, 144 
estimation of albumen, 148, 
152, 154 
of cholesterin, 155 
of fibrin, 150 
of hemoglobin, 157 
of lecithine, 156 
of mineral salts, 149 
of solid matter, 149 
of water, 149 
general chemical properties, 
141 
composition, 147 
in urine, 102 
normal constituents, 140 
quantitative analysis, 146 
serum of, 141 
analysis, 153 
Blood stains, detection of, 161 
Blue pus, 173 
Bone, 180 
analysis of, 181 
calculation of analysis, 184 
composition of, 186 
estimation of calcium, 182 
of carbon dioxide, 181 
of magnesium, 183 
of organic matter, 183 
of phosphoric acid, 183 
general chemical properties, 
180 
Brucine, detection in cases of 
poisoning, 287 
Butter, estimation in milk, 200 
rapid approximate estimation, 
204 
CALCIUM, estimation in ashes, 
224 
in bone, 182 
Calcium oxalate, 23 
as urinary sediment, 133 INDEX. 
307 
Calcium oxalate— 
as urinary calculi, 138 
Carbon dioxide, estimation in 
bone, 181 
in water, 297 
Carnine, 44 
Casein, 74 
estimation, 199 
in milk, 198 
Chlorine, estimation in ashes, 
225 
in urine, 117 
Cholesterin, 32 
estimation in biliary calculi, 
195 
in blood, 155 
Choline, 58 
Chondrin, 77 
Codeine, detection in cases of 
poisoning, 284 
Colostrum, 212 
analysis of, 214 
Conine, detection in cases of 
poisoning, 278 
Copper, detection in cases of 
poisoning, 257 
occurrence in biliary calculi, 
195 
quantitative estimation, 260 
tests for, 259 
Cream, composition of, 196 
proportion in milk, 198 
Creatine, 46 
detection in blood, 144 
in muscular juices. 175 
Creatinine, 48 
detection in urine, 49 
estimation in urine, 116 
Cystine, 59 
detection in urine, 100 
in urinary calculi, 137 
Desiccation, 15 
Dialysis, 14 
T?GG albumen, 66 
Xj Evaporation, 14 
Excrements, 217 
Excretin, 33 
Expectorations after thoracente- 
sis, 171 
Extraction, 14 
Extracts of glands, 179 
of muscles, 175 
Fatty adds, 17 
Ferments, animal, 74 
Fibrin, 71 
detection in serous liquids, 167 
estimation in blood, 150 
Fibrinogen and fibrinoplasmin, 
71 
Filtration, 14 
Formic acid, 18 
Gastric juice, 190 
analysis of, 191 
estimation of hydrochloric 
acid, 191 
Gelatin, 77 
Glandular juices, 179 
Globulin, 67 
Glucose, 27 
Bottger’s test, 28 
detection in blood, 144 
in urine, 95 
estimation in urine, 123 
Fehling’s test, 28 
Moore’s test, 27 
Trommer’s test, 27 
Glycogen, 31 
Gmelin’s test for biliary pig- 
ments, 80 
Guanine, 44 
HEMATIN, 70 
detection in blood stains, 
163 
hydrochloride, 70 
Hemin crystals, 70 
obtained from blood stains, 
164 
Hemoglobin, 68 . 
detection in blood stains, 163 
in urine, 102 
estimation in blood, 157 
reduced, 69 
Hippuric acid, 37 
estimation in urine, 115 
Hydrobilirubin, 81 
Hydrocele, effusion in, 170 308 
INDEX. 
Hydrocyanic acid, 269 
Hydropisin, 67 
Hypoxanthine, 43 
extraction from muscular 
juices, 177 
INCINERATION, 16 
X Indican, 83 
detection in urine, 84 
Indigotine, 84 
Indirubin, 85 
Inosite, 29 
detection in urine, 133 
extraction from muscles, 177 
Lactic acid, 20 
detection in urine, 97 
Lactobutyrometer, 204 
Lactodensimeter, 209 
Lactose, 30 
estimation in milk, 197, 204 
Lead, detection in cases of poi- 
soning, 253 
detection in water, 256 
in organic mixtures, 253 
quantitative estimation, 256 
tests for, 255 
Lecithine, 58 
Leucine, 50 
detection in urine, 100 
MARSH’S test, 237 
Meconic acid, detection, 282, 
284 
Melanine, 78 
Mercury, detection in cases of 
poisoning, 248 
electrolytic test, 251 
quantitative estimation, 252 
separation from organic mix- 
tures, 249 
tests for, 249, 250 
Metalbumen, 68 
Milk, analysis of, 197 
Baumhauer’s method of analy- 
sis, 202 
casein in, 198 
Chevalier and Henry’s method 
of analysis, 201 
Milk- 
commercial analysis of, 209 
cow’s, 207, 208 
density of, 197, 209 
detection of adulterations, 
209 
diseased, 211 
estimation of butter, 200, 204 
of casein, 199, 206 
of fat, 199 
of lactose, 199, 204 
of mineral salts, 200 
ewe’s, 208 
general properties, 196 
goat’s, 208 
Lehmann’s method of analy- 
sis, 206 
mare’s, 208 
Millon and Commaille’s me- 
thod of analysis, 199 
proportion of butter, 206 
of cream, 198 
of mineral salts, 207 
of water, 197 
rapid estimation of butter by 
lacto-butyrometer, 204 
sow’s, 208 
various analyses of, 207, 208 
woman’s, 208 
Millon’s reagent, 62 
Moore’s test for glucose, 27 
Morphine, chemical tests for, 283 
detection in cases of poisoning, 
280 
Uslar and Erdmann’s method, 
280 
Wormley’s method, 281 
Mucin, 78 
Muscular juices, 175 
analysis of, 175, 177 
Myosin, 72 
YTARCOTINE, detection in cases 
1.1 of poisoning, 284 
Neurine, 53 
Nicotine, detection in cases of 
poisoning, 279 
Nitric acid, detection in cases of 
poisoning, 266 
normal solution of, 296 
Normal solutions, 293 INDEX. 
309 
OPIUM, detection in eases of 
poisoning, 280 
Ossein, 77 
Oxalic acid, 22 
detection in cases of poison- 
ing, 268 
estimation, 269 
Oxaluric acid, extraction from 
urine, 45 
Oxyhemoglobin, 68 
PANCREATIC ferments, 76 
Pancreatin, 67 
Paralbumen, 67, 168 
Pepsin, 75 
Peptones, 64, 73 
Pettenkoier’s test for biliary 
acids, 56, 97 
Phosphoric acid, detection in 
ashes, 220, 222 
estimation in-ashes, 225 
in bone, 183 
in urine, 118 
Phosphorus, detection in cases 
of poisoning, 273 
Pigments, animal, 78 
Pleuritis, effusion in, 170 
Poisons, detection of, 227 
alkaloid, 275, 289 
mineral, 290 
volatile, 289 
Ptyalin, 74 
detection in saliva, 188 
Pus, 172 
blue, 173 
Pus corpuscles, 173 
Pyin, 172 
Pyocyanin, 173 
||EINSCH’S test, 236 
O ALIYA, 187 
kd analysis of, 188 
Salivary calculi, 189 
Sarcine, 43 
Scheele’s green, 229 
Serolin, 33 
Serous effusions, special, 170 
Serous liquids, analysis of, 167 
quantitative analysis of, 169 
i Serum of blood, 141 
analysis of, 153 
Sodium carbonate, normal solu- 
tion of, 29,6 
Sodium hydrate, normal solution 
of, 296 
Solution, 13 
Spermatic fluid and stains, 214 
Spermatozoids, 215 
in urine, 130 
Stains, blood, detection of, 161 
mineral acids, detection of, 267 
seminal, detection of, 214 
Standard solutions, advantages 
of, in analysis of urine, 
300 
preparation of, 300 
Stercorin, 33 
! Strychnine, detection in cases of 
poisoning, 285 
Sulphate of indigo, detection in 
cases of poisoning, 264 
Sulphuric acid, detection in 
cases of poisoning, 264 
estimation in ashes, 224 
in urine, 121 
normal solution of, 296 
Syntonin, 73 
TARTAR emetic, detection in 
cases of poisoning, 244 
Taurine, 54 
Tin, detection in cases of poison- 
ing, 247 
Tyrosine, 52 
detection in urine, 100 
UREA, 34 
detection, 37 
detection in blood, 143 
estimation in urine, 106 
Esbach’s method, 113 
Liebig’s method, 106, 301 
Yvon’s method, 110 
extraction from urine, 35 
Urea nitrate, 35 
Urea oxalate, 36 
Ureometer, 111 
Uric acid, 39 
as urinary sediment, 127, 
133 310 
INDEX. 
Uric acid— 
detection, 40 
detection in blood, 143 
in muscles, 177 
estimation in urine, 114 
extraction from small quan- 
tities of liquid, 41 
murexide test for, 40 
Uric acid calculi, 136 
Urinary calculi, 134 
albuminoid, 137 
ammonium urate, 136 
analysis of, 135 
calcium oxalate, 138 
cystic, 137 
mixed, 135, 139 
mulberry, 138 
phosphatic, 138 
uric acid, 136 
xanthic, 137 
Urinary sediments, 125 
organized, 130 
unorganized, 127 
Urine, 87 
abnormal constituents, 89 
accidental constituents, 89 
alkaline, 93 
approximate composition, 104 
blue and violet, 100 
cause of acidity, 92 
chemical examination, 90 
color, 94 
consistence, 90 
detection of abnormal coloring 
matter, 99 
of albumen, 94 
of ammonia, 103 
of biliary acids, 97 
of biliary pigments, 98 
of blood, 102 
of cystine, 100 
of fat, 133 
of glucose, 95 
of inosite, 96 
of lactic acid, 97 
of leucine, 101 
of tyrosine, 101 
estimation of albumen, 122 
Urine, estimation— 
of ammonia, 125 
of creatinine, 116 
of glucose, 123 
of hippuric acid, 115 
of mean daily acidity, 92 
of mineral salts, 105 
of phosphoric acid, 118 
of sodium chloride, 117 
of solid constituents, 105 
of sulphuric acid, 121 
of urea, 106 
of uric acid, 114 
of water, 105 
normal constituents, 88 
physical properties, 87 
quantitative analysis, 103 
quantity, 90 
rapid qualitative analysis, 103 
reaction, 91 
red, hepatic, 98 
specific gravity, 91 
Urobilin, 82 
Urocliromo, 83 
Urocyanin, 85 
Uroglaucin, 84 
Urohematin, 83 
Uroxanthin, 83 
Urrliodine, 85 
yiTELLIN, 67 
yy EIGHTS and measures, 303 
XANTHIN, 42 
extraction from muscular 
juices, 177 
ZINC, detection in organic mix- 
tures, 261 
Zinc lactate, 21 
Zinc paralactate, 22 STILLE & MAISCH’S DISPENSATORY—Second Edition-Now Ready. 
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CLOWES’ ELEMENTARY TREATISE ON PRACTICAL CHEM- 
ISTRY AND QUALITATIVE INORGANIC ANALYSIS. Spe- 
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and by Beginners. From the second and revised English edition, 
with about fifty illustrations on wood. In one very handsome royal 
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CLASSEN’S ELEMENTARY QUANTITATIVE ANALYSIS. Trans- 
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Prof, of Chemistry in the Towne Scientific School, Univ. of Pa. In 
one handsome royal 12mo. volume of 324 pages, with illustrations. 
Cloth, $2. (Now Ready.) 
GALLOWAY’S MANUAL OF QUALITATIVE ANALYSIS. From 
the sixth London edition. In one neat royal 12mo. volume, with 
illustrations (Preparing.) 
WOHLER AND FITTIG S OUTLINES OF ORGANIC CHEMISTRY. 
Translated with additions from the Eighth German edition, by Ira 
Remsen, M.D., Ph.D., Professor of Chemistry and Physics in Wil- 
liains College, Mass. In one volume, royal 12mo., of 550 pages. 
Cloth, $3. 
REMSEN’S PRINCIPLES OF THEORETICAL CHEMISTRY, with 
special reference to the Constitution of Chemical Compounds. In 
one handsome royal 12mo volume of over 232 pages. Cloth, $1 5 0. 
(Just Issued ) 
BOWMAN’S INTRODUCTION TO PRACTICAL CHEMISTRY, IN- 
CLUDING ANALYSIS. Sixth American, from the sixth and 
revised London edition. With numerous illustiations. In one 
neat royal 12mo. volume. Cloth, $2 25. 
HENRY C. LEA’S SON & CO.—Philadelphia.