HfiSBraM 
IBS LABORATORY MANUAL OF MEDICAL CHEMISTRY A LABORATORY MANUAL 
OF 
Medical Chemistry 
CONTAINING A SYSTEMATIC 
COURSE OF EXPERIMENTS 
IN 
Laboratory Manipulation and Chemical Action, the Non - Metallic 
Elements and the Medicinal Metals, Quantitative Processes 
applied to Sanitary Water Analysis, Medicinal Organic 
Compounds, Proteids, Digestion, Blood, 
Milk, Urinalysis and Toxicology 
IRA CARLETON CHASE, A.M. 
BY 
Professor of Chemistry and Toxicology in the Medical Department, and Professor of 
Analytical Chemistry in the Scientific Department of 
Fort Worth University 
FORT WORTH, TEXAS: 
Published by W. W. UNDERHILL 
1897 Copyright, 1897 
By IRA C. CHASE 
PRINTED AND BOUND BY 
J. HORACE MCFARLAND COMPANY 
mt. Pleasant printery 
Harrisburg, Pennsylvania PREFACE. 
This volume is the outgrowth of several years of lab- 
oratory instruction given medical students. The exercises 
have been used in various forms by seven classes since the 
organization of the Medical Department. They have been 
gradually shaped by the peculiar needs of students of medi- 
cine, and by personal visitation and careful study of the 
laboratories and methods of instruction in nearly all of the 
leading medical schools of the United States during the 
years 1893-6. 
Since there is not known to the author a small volume 
of modern, progressive laboratory exercises, covering the 
various branches of medical chemistry here presented, it 
has been decided to put these exercises into permanent 
form for the use of our own students. 
The aim has been to give such a scope to the earlier 
exercises as to quickly furnish the student a broad chem- 
ical foundation necessary to an appreciative understanding 
of the complex field of medical chemistry; to escape, on 
the one hand, the danger of teaching pure theoretical 
chemistry, unadapted to the needs of a physician; and, on 
the other, the more dangerous error of mechanically drill- 
V VI 
PREFACE. 
ing tests and operations which the student has not the 
chemical knowledge to remember nor intelligently apply. 
The work has been kept within such limits that it can 
be completed in two sessions by students working two lab- 
oratory periods each week. The more difficult and elaborate 
experiments have been reserved for the lecture table. 
The author trusts that the errors, so easily creeping into 
the first edition of a work covering so large a field, will be 
charitably regarded. 
Fort Worth University, I. C. C. 
Fort Worth, Texas, October 15, 1897. CONTENTS. 
PAGE 
Laboratory Manipulation and Chemical Action .... 1-13 
The More Important Non-Metallic Elements 15-53 
Reactions, Analytical and Synthetical, of the Princi- 
pal Medicinal Metals 55-77 
Gravimetric and Volumetric Processes Applied to 
Sanitary Water Analysis 79-89 
Medicinal Organic Compounds 91-118 
Physiological Chemistry, including Digestion, Blood, 
and Milk 119-144 
The Analysis of Normal and Morbid Urine 145-164 
The Toxicology of the Common Irritant and Neurotic 
Poisons 165-198 
Tables of Symbols, Valencies and Atomic Weights, and 
of Equivalent Weights and Measures 199-200 
Index 201-207 
VII EXERCISES 
IN 
LABORATORY MANIPULATION 
AND 
CHEMICAL ACTION PRACTICAL MEASUREMENTS. 
1. Comparison of English and Metric Length Units. 
1. Measure with the rule the length of several objects 
in both systems. 
2. Familiarize the length of a centimeter and decimeter. 
3. Note the number of centimeters in an inch. 
4. Measure the area of a book cover in square inches 
and square centimeters. Express each of these areas in 
decimal parts of a square yard and a square meter, respec- 
tively. Note how much more difficult it is to reduce the 
English than the metric measures. 
2. Comparison of English and Metric Volume Units. 
1. Using graduates, determine the capacity of the dif- 
ferent sized test tubes, beakers and evaporating dishes in 
ounces, drachms and cubic centimeters (c.c.). 
2. Note the number of cubic centimeters in a drachm. 
3. Express the volume of your beaker in parts of a gallon 
and parts of a liter. Note the advantage of the metric 
system. 
3. Comparison of English and Metric Weight Units. 
1. Weigh out 5 grains of calomel, 5 grains of antifebrin 
and of a grain of atropine hydrosulphate. 
2. Note the number of grains required to balance a 
gram weight. 4 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
3. Weigh out 1 gram (g.) and 10 grams of salt. Remem- 
ber the quantity by noting how large a coin each quantity 
might just be piled upon. 
4. Comparison of English and Metric Temperature Units. 
1. Examine the Fahrenheit and Centigrade thermometers, 
noting the comparative freezing and boiling points. 
2. Note the number of degrees F. corresponding to i° C. 
5. Reduction of English and Metric Units. By the fol- 
lowing rules,1 reduce the prescriptions and temperatures 
written on the blackboard to corresponding units in the 
other system. 
Rule I. To Reduce Metric to English Weights and Mea- 
sures. Multiply the quantity in grams or cubic centimeters 
by 10, add and the result is grains or minims (nearly). 
Rule II. To Reduce English to Metric Weights and 
Measures. Divide the quantity in grains or minims by 10, 
subtract y,, and the result is grams or cubic centimeters 
(nearly). 
Rule III. To Reduce Fahrenheit to Centigrade Tempera- 
tures. Subtract 32, and multiply by ■§-. 
Rule IV. To Reduce Centigrade to Fahrenheit Tempera- 
tures. Multiply by and add 32. 
Noth i. Rules I and II are merely approximate, but near enough for physicians’ 
use, and are easily remembered and mentally applied. CONSTRUCTION OF APPARATUS. 
5 
CONSTRUCTION OF APPARATUS. 
6. Construction of a Stirring Rod. Select a solid or hol- 
low glass tube 8 inches long. Hold the ends in a Bunsen 
flame until the ends are melted together and neatly rounded. 
When cool, cap one end with a small piece of rubber tubing, 
to protect a glass beaker while stirring. 
7. Construction of a Dropper. Select a piece of glass 
tubing 8 inches long, that will snugly fit the rubber nipple. 
Heat this tube at the center, with constant rotation over the 
Bunsen flame. When hot, draw it out an inch and a half. 
With a file, scratch it in the center and break it. If it has 
been evenly drawn, two droppers may be made. Lay one- 
half aside for experiment 8 (b). Take the other and, heat- 
ing the larger end very hot, stamp it quickly on a cool metal 
surface, thus forming a ring to hold the rubber cap. 
8. Construction of a Generator. Select a 7-inch test 
tube and fit it with a i-hole and a 2-hole rubber stopper. 
This apparatus is referred to throughout the laboratory 
course as a “generator." It is used for a variety of purposes, 
and may have two kinds of fixtures, referred to as (a) a 
delivery tube, and (£) an ignition jet. A thistle tube added 
is often useful. Examine these generators on the demon- 
strator’s desk. Fit one up, and keep it constantly ready for 
use. 
(a) Construction of a Delivery Tube. Select a glass tube 
a foot long. One-third the distance from one end heat it 
evenly, with constant rotation, over a fish-tail burner. When 
hot, remove the tube from the flame and bend it into syphon 6 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
form. The bend should be uniform, with no “buckle” in 
the glass. 
Construction of an Ignition Jet. Round the ends of 
the tube saved in experiment 7, in the flame. When cool, 
insert it in the 2-hole cork for an ignition jet. 
(e) Construction of a Thistle Tube. Select a glass tube 8 
inches long. Heat one end very hot until closed with a bead 
of white-hot glass. Remove it from the flame and gently 
blow a bulb as large as a small marble. Next heat, with a 
blowpipe, a spot on the very top of the bulb until white-hot. 
Remove it from the flame and blow a quick, strong blast. 
The top will be blown out. Clean the edges from fine glass 
and round them by heating in the flame. This makes a 
small but serviceable thistle tube. Insert it in the cork by 
the side of the ignition jet, as in the “model” generator. 
9. To Mend a Test Tube. Heat the lower portion of a 
bottomless test tube, and when hot draw it together with a 
glass rod and draw away superfluous glass. Reheat the end, 
remove from the flame, and gently blow it into shape. The 
bottom should be round and quite thin, to stand heating. To 
mend a large tube or generator, it will be necessary to use 
the bellows and blast lamp. 
CHEMICAL MANIPULATION. 
io. Solution. Dissolve about i g. of common salt, NaCl, 
in a test tube of water, and preserve the solution. 
ii. Evaporation. Put a few drops of the above solution 
in a porcelain evaporating dish. Place this on a piece of CHEMICAL MANIPULATION. 
7 
wire gauze or asbestos board and heat it over a non-luminous 
Bunsen flame until dry. Water and salt can thus be sepa- 
rated by heat. 
12. Precipitation. Take half the remaining salt solution. 
Add nearly an equal quantity of silver nitrate, AgN03. A 
white precipitate falls. Set the tube aside for the next 
experiment. 
13. Filtration. Prepare a funnel, filter paper, ring-stand, 
and beaker, as on the demonstration desk. Shake the tube 
prepared in the last experiment, and pour the contents down 
a glass stirring-rod into the filter. Reject the solution caught 
in the beaker below. Save the precipitate (ppt.). 
14. Decantation. Precipitate the remainder of the salt 
solution left in experiment 12, by silver nitrate, AgNOg. 
Heat the tube, and set it aside until the precipitate settles, 
then pour off or decant the solution, leaving the ppt. 
15. Reduction. Bore a shallow hole in a piece of char- 
coal. In this place all the white ppt. formed in the above 
experiments. Turn down the Bunsen burner to a 2-inch 
luminous flame. Rest the blowpipe tip on the top of the 
burner. Blow gently and continuously from the cheeks, and 
heat the precipitate with the fine blowpipe flame until minute 
beads of metallic silver appear. 
16. Distillation. In a generator place a salt solution 
colored with indigo. Boil it, and condense the steam by 
letting the delivery tube dip in a test tube cooled by being 
immersed in a beaker of water. Taste the distillate, and 
note that both the color and salt have been removed. 
17. Dialysis. Make a small dialyzer by tying tightly a 
fresh, thin sausage skin over the mouth of a bottomless test 8 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
tube. In this place a mixture of salt, starch and water. 
Set this, skin down, in a beaker of water. After some time 
take some of the water from the beaker and add silver 
nitrate. A white precipitate indicates salt, which has pene- 
trated the membrane. The water in the beaker is not colored 
blue by tincture of iodine. The milky liquid in the dialyzer 
turns blue with iodine, showing that the starch has not 
passed through the membrane. 
18. Electrolysis. Prepare a solution of copper sulphate, 
CuS04, in a beaker. Attach a clean silver coin to the nega- 
tive electrode of the dynamo or battery. Suspend the coin 
and the positive wire in the liquid without their touching. 
Examine the coin after a few moments. 
LABORATORY QUESTIONS. 
1. Is the force which holds salt in solution a weak or strong one? 
2. How could you separate salt and water ? 
3. What is a filtrate? What is a precipitate? 
4. How may a precipitate be washed on the filter paper? 
5. How may a precipitate be washed by decantation? 
6. What is a distillate? 
7. Can silver be dissolved in water? 
8. Where did the copper come from which plated the coin ? 
9. Why was the coin hung on the negative electrode? 
10. What class of bodies passes through animal membranes ? CHEMICAL CHANGE. 
9 
CHEMICAL CHANGE. 
19. A Mechanical Mixture. Make a mixture in any 
proportion of fine iron filings and flowers of sulphur. Grind 
them together in a mortar. This is a mixture, because the 
iron and sulphur can be separated by mechanical means. 
(a) From a small portion of the mixture remove the iron 
by the use of a magnet. The sulphur will be left. 
(b) To another small portion add carbon disulphide, CS2. 
Shake it up. The sulphur will be dissolved. The iron will 
remain. Pour the solution into an evaporating dish and set 
it aside. The sulphur will be left in crystals when the CS2 
evaporates. 
20. A Chemical Compound. Several students together 
weigh out 56 g. of iron filings and 32 g. of flowers of sulphur. 
Mix and grind them thoroughly in a mortar. Take an inch of 
this mixture in a test tube. Heat it until the red-hot glow 
diffuses itself throughout the mass. Cool, break the test 
tube, and grind the mass in a clean mortar. This substance 
is now a chemical compound, FeS, because the iron and 
sulphur cannot be separated by mechanical, but only by 
chemical means. 
(1a) From a portion of the compound try to separate the 
iron by a magnet. It is all slightly magnetic, but no iron can 
be separated and sulphur left. 
(b) With another portion of the compound try to dissolve 
out the sulphur by carbon disulphide, CS2. If the work has 
been carefully performed, no sulphur will be found on evapo- 
rating the CS2. 10 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
Thus iron and sulphur can unite only in definite propor- 
tion by weight, as 56 parts of iron with 32 parts of sulphur. 
Any extra iron or sulphur will remain as a mixture. 
EVIDENCES OF A CHEMICAL CHANGE. 
21. An Elevation of Temperature. Powder separately a 
pinch of sugar and a pinch of potassium chlorate, KC103. 
Mix them on an iron plate, and touch the mixture cautiously 
with a drop of sulphuric acid, H2S04. Brilliant deflagration 
ensues. In general, every chemical combination is attended 
by an elevation of temperature. 
22. The Formation of a Precipitate. Make a solution of 
mercuric chloride, HgCl2, by dissolving a little of the salt in 
water. Do the same with a little tin chloride, SnCl2. The 
solutions should be clear. Mix the two, and a white ppt. falls, 
turning black, and sometimes by heating and stirring mer- 
cury will separate. The formation of a ppt. from two clear 
solutions indicates a chemical change, resulting in the forma- 
tion or liberation of a new insoluble substance. 
23. The Evolution of a Gas. Cover marble dust with 
water in a test tube and add a little dilute hydrochloric acid, 
HC1. A gas is given off. The evolution of a gas from two 
solid or liquid bodies indicates a chemical change, resulting 
in the formation of a new gaseous substance. 
24. A Change in Electrical Condition. Fill a beaker one- 
third full of water and add 20 drops of sulphuric acid, H2S04. 
Connect a zinc and a copper wire to a delicate galvanometer. 
Dip the wires, without touching each other, into the beaker 
of diluted acid. The acid forms a chemical compound with 
the zinc, and a current of electricity flows through the gal- CHEMICAL CHANGE. 
11 
vanometer from the copper to the zinc, as indicated by the 
movement of the needle. In general, it is supposed that 
every chemical change is attended by a change of electrical 
condition. 
25. A Change of Color. Touch a crystal of sugar of lead, 
lead acetate, Pb(C2H302)2, with a drop of a potassium iodide, 
KI, solution. A new yellow-colored compound is formed. 
A change of color is often an evidence of a chemical change, 
resulting in the formation of a new and differently colored 
substance. 
26. A Change of Reaction. Place in a beaker a little 
dilute hydrochloric acid, HC1. Add a small piece of blue 
litmus paper. The paper turns red and the solution tastes 
sour. Add some sodium hydroxide, NaOH, solution, with 
constant stirring until the paper turns faintly blue. The 
solution loses its acidity, and tastes salty. A change in 
the reaction of a solution toward litmus paper indicates a 
chemical change, resulting in the union of an acid and an 
alkali to form a new compound. 
SOME CAUSES INDUCING A CHEMICAL CHANGE. 
27. Heat. Place a few grains of sugar in the bottom of a 
test tube. Heat gently. Note the carbon remaining and the 
water on the sides of the tube. Heat in general favors 
chemical change by increasing the molecular motion, destroy- 
ing old and encouraging new combinations. 
28. Light. Make a solution of salt, NaCl, and add some 
silver nitrate solution, AgNOg. A white ppt. falls. Filter 
the solution. Place the filter paper, with its white silver 
chloride, in the sun. It soon turns bluish black, from a 
chemical change due to the energy of the sunlight. 12 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
29. Electricity. Wet a piece of filter paper in starch 
mucilage test solution (see 57, Note 1). Lay this on a metal 
plate. Firmly press the wire from the negative electrode of 
the dynamo or battery on the plate, and with the wire from 
the positive electrode write slowly upon the paper. A blue 
line is traced. The color is due to a chemical change, 
caused by electric energy. 
30. Mechanical Energy. Notice that dry quicklime, CaO, 
and dry ammonium chloride, NH4C1, have no odor. Mix a 
little of each very loosely in a mortar. They have no odor. 
Press and rub them firmly with a pestle. An odor of ammo- 
nia is evolved, and the mixture grows moist. The intimate 
union caused by pressure has induced a chemical change. 
31. Solution. Mix in a beaker some dry powdered 
sodium bicarbonate, NaHC03, and powdered tartaric acid, 
H2(H4C406). No action ensues. Add water. Gas is evolved. 
In general, solution favors chemical action by separating 
atoms and molecules, and bringing them into intimate 
association. 
LABORATORY QUESTIONS. 
1. What is meant by an element; an atom; a molecule; valence, 
and bond ? 
2. What is a mechanical mixture? A chemical compound? 
3. Name several mechanical mixtures and chemical compounds in 
nature. 
4. What is meant by the indestructibility of matter? 
5. What is the law of definite proportion? How is it proved? 
6. What is the law of multiple proportion? 
7. In the manufacture of FeS(2o), what was the most striking evi- 
dence of a chemical change? 
8. When ammonium nitrate and sodium sulphate are dissolved the 
solution becomes cold. What evidence is thereof a chemical change? 
9. Is ice cream frozen by a chemical change? CHEMICAL CHANGE. 
13 
10. From what force is most of the energy of the world obtained ? 
11. What power unites chemical elements? How does it seem 
related to electricity or magnetism. 
12. When a solid compound is dissolved, are the atoms separated? 
13. Is solution a chemical change? 
14. What is meant by atomic and molecular weight? 
15. What is the molecular weight of one of the most complex sub- 
stances known, provided its exact formula be C6ooHfl6oNi54FeS3Oi79 
(oxyhaemaglobin) ? 
16. What is a graphic formula ? LABORATORY EXERCISES 
IN THE 
MORE IMPORTANT 
NON-METALLIC ELEMENTS HYDROGEN. 
17 
HYDROGEN. 
Useful Data : Atomic Symbol, H; Molecular Formula, H2 ; 
Valence, 1 ; Atomic Weight, 1 ; Electro-positive; 1 liter at O0 C. and 
760 m.m. weighs .0896 g. 
32. Preparation from Water by Sodium. Fill a test tube 
one-third full of water. Drop into it a small piece of metallic 
sodium, Na. Quickly apply a flame to the mouth of the 
tube. H burns with a pale blue flame. When the action 
ceases, test the remaining liquid by the touch, taste and 
action on red litmus paper. Evaporate the solution. Ex- 
amine the salt remaining, which is sodium hydrate, NaOH, 
or solid caustic soda. 
d _j_ — _j_ 
Reaction—H20+Na=NaOH+H. 
33. Preparation from Hydrochloric Acid by Zinc. In a 
generator put 10 g. of granulated zinc, Zn, covered with 
water. Add a little hydrochloric acid, HC1. Collect several 
test tubes of H by the displacement of water, as illustrated 
on the demonstration desk. Light the H in one test tube. 
Transfer the H from one test tube to another, remembering 
that it is lighter than air. Prove its presence in the last 
tube by igniting it. After the action in the generator 
entirely ceases, pick out the Zn remaining, and return it to 
the container. Filter the solution. Evaporate it to a small 
bulk, and set aside to cool. Crystals of zinc chloride, ZnCl2, 
will separate. 
+ -\ + H 
Reaction—Zn+2HC1—H2+ZnCl2. 18 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
34. Preparation by Electrolysis. Fill a beaker with water 
and add 15 drops of sulphuric acid, H2S04. In this invert a 
test tube filled with water. Keep the two electrodes from 
the dynamo or battery separated, and insert them in the 
beaker. Collect the tube half full of the gas arising from the 
negative electrode, from which the greater number of bubbles 
arises. Cover the tube with the thumb. Invert it, apply a 
flame to the gas, and prove that it burns like H. 
H + — 
Reaction—H20=H2+0. 
LABORATORY QUESTIONS 
1. Name a number of substances which contain H. 
2. Can H be prepared from any substance which does not contain it? 
3. How many atoms of H in two molecules? 
4. What were the qualities of the solution remaining in 32? 
5. How much will 120 c.c. of H weigh under standard conditions? 
6. How do the experiments prove H electro-positive? 
7. From the experiments, which would one judge more strongly 
electro-positive, H or Zn? 
8. How much H is contained in a pound of water, H20? In a 
pound of HC1? 
9. Is H soluble in water ? 
10. How does the H flame differ from that of illuminating gas? 
xi. Does H in the experiments act like a metal? 
12. Were all these experiments examples of chemical change? Why? 
13. Were any materials used in these experiments destroyed? 
14. Would Zn and H be likely to form a stable chemical compound? 
Why? CHLORINE. 
19 
CHLORINE. 
Useful Data : Atomic Symbol, Cl; Molecular Formula, Cl2; 
Valence, i ; Atomic Weight, 35.5; Electro-negative ; 1 liter at O0 C. and 
760 m.m. weighs 3.173 g. 
35- Preparation from Hydrochloric Acid by Manganese 
Dioxide. Place a little manganese dioxide, Mn02, in a 
generator. Add hydrochloric acid, HC1, and warm gently. 
Note the color, odor and specific gravity of the gas1 as it 
rises in the tube. Wash the material quickly into the 
sewer. 
_|_ — _j _| -| — 
Reaction—Mn02 -f 4HCI = MnCl2 + 2H20 4- 2C12. 
36. Preparation from a Chloride. In a generator mix 
two parts of sodium chloride, NaCl, and one part of man- 
ganese dioxide. Add some sulphuric acid, H2S04, and 
gently warm. Pass the yellow gas into half a test tube of 
water, thus forming chlorine water. In a part of this a 
scale of gold leaf will dissolve. Set the rest away in the 
sun, and notice after some hours the change in color, 
odor, taste and action on litmus paper. It turns to hydro- 
chloric acid, HC1. 
Reaction— 
_j _j _l_ — -|- — + — + — — 
(1) 2NaCl + Mn02 -f 2H2 S04 = Na2S04 + MnS04 + 2H20 + 2Cl. 
Or it may be written in two stages, thus : 
H— + — + — H 
First. 4NaCl + 2H2 SO4 = 2Na2 SO* + 4HCI. 
_j_ — _j_ — _|_ — -f- — 
Second. 4HCI + Mn02 = MnCl2 + 2H0 O + 2Cl2, as above. 
(2) 
Note i. Care should be taken not to allow any considerable amount of Cl to escape 
in the laboratory. When inhaled it produces great irritation. 20 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
37. Preparation from Bleaching Powder by an Acid. 
Place some bleaching powder in a generator. Add dilute 
acid. Hold a little damp litmus paper, colored cloth, red 
ink writing or other organic colors in the gas. The colors 
are bleached. The color does not return when they are 
moistened with ammonia water, NH4OH. 
38. Preparation from Hydrochloric Acid by Electrolysis. 
Put some hydrochloric acid into a test tube. Insert the 
carbon electrodes of the dynamo or battery, keeping them 
separate. Note that, as before, H is liberated from the 
negative electrode. Cl is liberated from the positive elec- 
trode, and dissolves in the water, forming yellow chlorine 
water. Note the odor of chlorine. 
H— ~f- — 
Reaction—HC1 = H + Cl. 
39. Preparation of Chlorine Water. Place a few crystals 
of potassium chlorate, KC103, in a test tube. Add 3 c.c. 
of hydrochloric acid. Warm until Cl escapes freely, then 
fill the tube with water. This is the most convenient 
way to prepare a little fresh chlorine water, so frequently 
needed in testing. The salt and acid present do not 
interfere with its use. 
Reaction—2HCI + 2KCIO3 == 2KCI + 2H20 + C1204 + 2CI. 
COMPOUNDS OF CHLORINE AND HYDROGEN. 
Hydrochloric Acid (Muriatic Acid), HC1. 
40. Preparation by Synthesis. Fill two test tubes, one 
with H and the other with Cl, from the generators in the 
hood. Join their mouths. Invert several times, to mix. 
Cautiously open the mixture to a flame. After combina- 
tion, shake the gas in the two tubes with 5 c.c. of water. CHLORINE. 
21 
Test this by taste and blue litmus and set it aside, and 
later prove the presence of HC1 by 43. 
Reaction—H + Cl = HC1. 
41. Preparation from a Chloride by Sulphuric Acid. In a 
generator cover 5 g. of sodium chloride with sulphuric acid, 
H2S04. Warm, and cautiously note the odor. Hold moist 
blue litmus paper in the gas until it changes to red. Pass 
the gas through 10 c.c. of water. A solution of HC1 forms, 
which is the muriatic acid of commerce and medicine. Try 
to boil the HC1 from the solution. 
Reaction—sNaCl + H2S04 = Na2S04 + 2HCI. 
42. Formation of Chlorides. In an evaporating dish 
put 15 c.c. of HC1. Add a gram of iron filings and gently 
warm for ten minutes. Fill the dish with water. Filter, 
evaporate the clear filtrate to a small bulk, and set aside. 
After a few moments fine crystals of green ferrous chloride, 
FeCl2, will form. 
_|_ _|_ — 
Reaction—Fe-|-2HC1 = FeCl2-f-H2. 
43, The Silver Nitrate Test for Chlorides. Silver nitrate, 
AgN03, added to a solution of chlorides, precipitates white 
silver chloride, AgCl, which is soluble in ammonia but 
insoluble in nitric acid. 
44. Detonation of Chlorates. Place in an iron mortar two 
small crystals of potassium chlorate, KC103. Add a few 
grains of dry sugar or flowers of sulphur. Very gently rub 
them to a powder and strike the mixture with the pestle. A 
sharp explosion will occur. 
45. The Ignition Test for Chlorates. A solution of potas- 
sium chlorate, KC103, yields no precipitate with silver nitrate, 22 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
AgNOg. Ignite a crystal of KClOg on a piece of glass or 
porcelain1. Cool, and dissolve the residue. The chlorate 
has turned to a chloride, and its solution yields the test for 
chlorides with silver nitrate, 43. 
LABORATORY QUESTIONS. 
1. Name several substances that contain chlorine. 
2. Are all substances containing chlorine chlorides ? 
3. When is a solution neutral to litmus ? 
4. How many substances can you find that turn red litmus blue? 
Blue litmus red? 
5. How do the experiments prove chlorine electro-negative? 
6. Write the reaction which chlorine water undergoes in the sun? 
7. What two compounds form the pure hydrochloric acid of commerce ? 
8. Why is HC1 called “spirit of salt”? What are muriates? 
9. How much Cl in one pound of salt ? 
10. How much NaCl is required to manufacture one pound of HC1 ? 
ri. Outline a good method for bleaching white cloth? 
12. How would one proceed to disinfect a room with chlorine? 
13. If Cl unites with water, to what substance is the bleaching due ? 
14. Write the symbols for K, Cu, Au, Sn, Hg, Al, Mn, Ca, Ba and 
NH4 chlorides. 
15. How might all these chlorides be formed? 
16. What chloride was formed in the preparation of H ? 
17. What chlorides were formed in the preparation of Cl ? 
18. What results when chlorates are triturated with organic sub- 
stances ? 
19. To what acid is sodium chloride related? 
20. To what acid is potassium chlorate related? 
Note i. See the reaction occurring here, 55, where it will be noted that oxygen is 
at the same time liberated. BROMINE. 
23 
BROMINE. 
Useful Data: Atomic Symbol, Br; Molecular Formula, Br2; 
Valence, 1 ; Atomic Weight, 80; Electro-negative. 
46. Preparation from a Bromide. In a generator, mix 
three well-powdered crystals of potassium bromide, KBr, 
with an equal quantity of manganese dioxide, Mn02. Add 
sulphuric acid, H2S04, and warm gently. Note the color, 
odor, specific gravity and bleaching qualities of the gas as it 
rises in the tube. If possible, pass the gas through water, 
forming bromine water. Set this aside for future use. 
Reaction— 
2 K B r-}-M n 02+2 H2S 04 = K2S 04M n S 04-(-2 H20B 
COMPOUNDS OF BROMINE AND HYDROGEN. 
Hydrobromic Acid, HBr. 
47. Preparation from a Bromide by Sulphuric Acid. Place 
a crystal of KBr in an evaporating dish. Add a few drops 
of sulphuric acid, H2S04, and warm. Note the white vapors 
of HBr mixed with some yellowish brown vapors of free 
bromine. 
Reaction—2KBr-j-H2S04= K2S04+2HBr, 
and 
2HBr-i-H2S04 S02+2H20-f-Br2. 
48. Preparation from a Bromide by Hydrogen Sulphide. 
Take a test tube of bromine water, containing a globule of 
carbon disulphide, CS2. Pass through this hydrogen sul- 
phide, H2S, from the generator in the hood. Shake well, 24 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
and pour off the clear solution containing HBr. Preserve 
this for the following tests. 
Reaction—2Br -j- H2S = 2HBr -f- S. 
49. Tests for Bromides. 
1. The Chlorine Test. To a solution of bromides add a 
globule of carbon disulphide, CS2 (chloroform may be used). 
Next add some chlorine water and shake. Free Br is liber- 
ated, and tinges the CS2 yellow to brownish red, according 
to the amount present. 
2. The Silver Nitrate Test. AgNOs ppts. in solutions of 
bromides yellowish white, AgBr. Insoluble in nitric acid, 
HNOg, and sparingly soluble in dilute ammonium hydroxide, 
NH4OH. 
3. The Starch-bromide Test. When starch water is 
added to a solution of bromides and Br liberated by a 
few drops of chlorine water, yellow starch bromide is 
formed. 
IODINE. 
Useful Data : Atomic Symbol, I; Molecular Formular, I2 ; Va- 
lence, 1; Atomic Weight, 127; Electro-negative. 
50. Physical Properties. Note the characteristics of 
metallic iodine. Heat a crystal in a dry test tube. Notice 
the color of the vapor, and the minute crystals sublimed 
on the side of the tube. Try to dissolve the crystals in 
water. Next try alcohol. Next try carbon disulphide or 
chloroform, and note the differences. IODINE. 
25 
50 1-2. Preparation from an Iodide. In a generator 
mix a crystal of KI with manganese dioxide, Mn02. Add 
sulphuric acid and warm gently. Note the violet vapors 
of iodine as they rise in the tube. 
Reaction— 
2KI -f Mn02 + 2H2S04 =MnS04 + K2S04 + 2H20 + I2. 
COMPOUNDS OF IODINE AND HYDROGEN. 
51. Preparation from Iodine. Prepare a test tube con- 
taining a globule of CS2, a crystal of I and some water. 
From the generator in the hood pass hydrogen sulphide 
gas, H2S, through the mixture. Hydriodic acid remains in 
solution. 
Hydriodic Acid, HI. 
Save this solution for the following tests. 
Reaction—2I -j- H2S= 2HI -f- S. 
52. Tests for Iodides. 
1. The Chlorine Test. To a solution of iodides add a 
globule of carbon disulphide, CS2, or chloroform. Next 
add chlorine water, and shake. Free I is liberated and 
colors the globule violet to black, depending upon the 
amount present. 
2. The Silver Nitrate Test. AgN03, added to a solution 
of iodides, ppts. light yellow, Agl ; insoluble in nitric acid, 
HN03, and sparingly soluble in dilute ammonium hy- 
droxide, NH4OH. 
3. The Starch-iodide Test. When starch water is added 
to a solution of iodides, and free iodine liberated by a few 
drops of chlorine water, blue starch iodide is formed. 26 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
FLUORINE. 
Useful Data : Atomic Symbol, F; Valence, 1 ; Atomic Weight, 
19 ; Electro-negative. 
COMPOUNDS OF FLUORINE AND HYDROGEN 
Hydrofluoric Acid, HF. 
53. Preparation from a Fluoride. First cover one side 
of a glass plate with an even coating of paraffin, and with 
a sharp point scratch a name or design through the wax. 
Next moisten 10 g. of calcium fluoride, CaF2, with sul- 
phuric acid, H2S04, in a lead dish. Warm this for a few 
seconds only. Note the irritating odors of HF which 
arise. Observe that they are acid to litmus paper. Place 
two match sticks across the top of the dish and cover it 
with the glass plate, wax side down. After half an hour 
remove the wax, and the design will be found etched in 
the glass. 
Reaction — CaF2 -{- H2S04 = CaS04 -f- 2HF, and HF at- 
tacks the silica of the glass thus : 4HF -j- Si02 = SiF4 -f- 2H20. 
LABORATORY QUESTIONS. 
1. What per cent of KI is I? 
2. What substances did you find would dissolve I? 
3. Will I dissolve in KI solution? Try it. 
4. Can iodine or iodides be detected by putting a drop of their 
solution on one’s cuff? 
5. Complete the equation NaBr + HgN03 = 
6. Balance the equation KOH + I = KI03 + KI + H20. 
7. What are the white fumes seen escaping in etching? 
8. What becomes of the sulphur set free in experiments 48 and 51 ? OXYGEN. 
27 
9. How do you explain the change of color of the CS2 globule in 
experiments 48 and 51? 
xo. Write the reaction for preparing I from Fel2. 
11. Why is HC1 a more useful acid than HF or HI? 
12. Can you invent a method of preparing NaBrfrom Br and NaOH? 
13. Would Br be valuable for a disinfectant? Why? 
14. How do the experiments prove Br, I and F electro-negative? 
15. Arrange Cl, Br, I and F in the order of their atomic weights. 
Is this the order of their chemical affinity? 
16. Taste the compounds of Cl, Br and I, and assign a reason why 
Berzelius designated them as “halogens” (salt formers). 
17. How many reasons can you assign for classifying Cl, Br, I and 
F in one family ? 
18. Why cannot the hydrogen compounds of the halogens all be 
prepared by the action of sulphuric acid on their salts? 
19. If the chlorine test be applied to a mixture of iodides and 
bromides, can these elements both be detected? Try it by adding 
small amounts of chlorine water and shaking until a large amount 
has been added. Note any characteristic colors in the globule. 
20. Why could chlorides, bromides or iodides not be prescribed in 
solution with mercurous, silver or lead salts ? 
21. Compare the reactions for the preparation of Cl, Br and I from 
their salts. What similarity is found? 
OXYGEN. 
Useful Data : Atomic Symbol, O; Molecular Formula, 02 ; 
Valence, 2 ; Atomic Weight, 16 ; Electro-negative ; Specific Gravity, 
1.1056 (Air is 1); Weight of r liter at O0 C and 760 m.m., 1.430 g. 
54. Preparation for Mercuric Oxide. Place 1 g. of mer- 
curic oxide, HgO, in a small test tube. Heat it very hot and 28 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
insert a glowing match stick from time to time until it bursts 
into flame. Examine the sides of the 1.1. Notice the change 
of color of the remaining oxide as it cools. 
Reaction—2HgO=2Hg + 02. 
55. Preparation from Potassium Chlorate. Place 2 g. of 
potassium chlorate, KC103, in a test tube. Heat and test for 
O, as before. Continue to heat until the action ceases. 
Compare the taste of the residue with that of potassium 
chlorate. See 45. 
Reaction—2KC103 = 2KCI -(- 302. 
56. Preparation from a Chlorate by Manganese Dioxide. 
Place 2 g. of KCIO3 in a test tube and mix the crystals with a 
little manganese dioxide, Mn02 (fine dry sand is nearly as 
good). Heat and test for O, as before. Note that the gas 
is evolved with less heat and the Mn02 is unchanged. 
Reaction—2KCIO3 Mn02 = Mn02 2KCI -f- 302- 
OZONE—Molecular Formula, 03. 
57. Preparation from Ether. Put a little ether in a test 
tube, and keep it away from flames. Over it hold a piece of 
damp starch test paper1. Heat the end of a glass rod very 
hot, and with it stir the ether. Ozone is formed, and turns 
the starch paper blue. 
58. Preparation by Electricity. Notice the peculiar odor 
of ozone about a Holtz or other electric machine when in 
action. Detect its presence by holding starch test paper 
near the discharge. 
Note i. Starch test paper is made by boiling some thin starch water, dissolving in 
it a little KI, and in this dipping the paper. Any substance which will unite with the 
K will leave the 1 free to form blue starch iodide. OXYGEN. 
29 
COMPOUNDS OF OXYGEN AND HYDROGEN. 
Water, H20. 
59. Preparation by Synthesis. Prepare a hydrogen gen- 
erator with an ignition jet. In it cover Zn with water and 
add some sulphuric acid. After it has been acting some 
moments, and the air is all expelled, wrap it in a cloth and 
light the gas. Hold over the flame an inverted beaker kept 
cool, if necessary, by a damp cloth wrapped about it. Notice 
that the moisture gathers within the beaker. 
Reaction—H2+0=H20. 
60. Composition of Water Proved by Analysis. Fill a 
beaker with water acidulated with sulphuric acid, H2S04. 
Invert in this two test tubes filled with water. Insert in the 
beaker the electrodes of the dynamo or battery. Collect the 
gases in separate tubes until a quantity of each is obtained. 
Note that in the same time twice as much of one gas as the 
other is collected. Place the thumb under the mouth of each 
tube in succession, invert and test the one for hydrogen by 
igniting the gas, and the other for oxygen by the glowing of 
a smouldering match. 
61. Preparation from Barium Dioxide. Place 10 g. of 
barium dioxide, Ba02, in a beaker of cold water. Let it 
stand, and stir repeatedly for half an hour. Stir, and add 
slowly 20 c. c. of sulphuric acid, H2S04. Let it stand, 
and finally filter or decant the clear solution. It contains 
h2o2. 
Hydrogen Dioxide, H202. 
62. The Chromate Test for Hydrogen Dioxide. Mix in 
a test tube 1 drop of potassium bichromate solution, 30 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
K2Cr207, 2 drops of H2S04, and a little ether. Lastly, 
add a few drops of H202, and shake. The supernatant 
ether becomes blue from the presence of perchromic acid, 
H2Cr208, in solution. 
TWO CLASSES OF OXIDES. 
63. I. Acidic Oxides. Place a piece of dry phosphorus 
in an evaporating dish. Ignite it and quickly cover it 
with a glass plate, admitting as little air as is necessary 
to totally consume it. When action ceases examine the 
white powder, phosphoric oxide, P205. It has no action 
on dry blue litmus paper. Add some water. The solution 
is acid toward litmus, and has a sour taste. Phosphoric 
acid, H3PO4, is formed. Electro-negative chemical ele- 
ments in general form oxides which unite with water, 
forming acids. 
Reaction—P2-}"05— P2O5 > P2®5- — 2H3PO4. 
64. II. Basic Oxides. In an evaporating dish ignite a 
dry piece of metallic sodium. The white residue is sodium 
oxide, Na20. It has no action on dry red litmus paper. 
Add water. Sodium hydroxide, NaOH, is formed, which 
is alkaline to litmus, and has the biting taste and greasy 
touch of an alkali. Strong electro-positive elements form 
oxides, which unite with water, forming hydroxides. 
Most metallic oxides are insoluble in water. 
Reaction—2Na-f 0 = Na20 ; Na20-|-H20 = 2Na0H. 
65. The Union of Acids and Alkalies. Place in a beaker 
a solution of sodium hydroxide, NaOH. It turns red lit- 
mus paper blue. In another beaker put some dilute HC1. 
It turns blue litmus red. Add one mixture to the other OXYGEN. 
31 
until the resulting solution has no action on litmus. This 
is best accomplished by putting a few drops of phenol- 
phthalein in the acid and adding the alkali drop by drop 
until on stirring a faint pink color appears. Evaporate 
this neutral solution to dryness, and taste the crystals of 
sodium chloride, NaCl, remaining. Acids and alkalies 
always unite to form a salt and water. 
Reaction—NaOH -f- HC1 = NaCl -f- H20. 
1. How much O can be obtained from ioo g. of KC103? From 
ioo g. of HgO ? 
2. Can you invent a method of preparing HgO? 
3. Explain the action of Mn02 in the preparation of O. 
4. Why is O “smoky” when first prepared? 
5. Why does ozone turn starch test paper blue and O not? 
6. What is the compound formed when iron rusts? Give the 
formula. 
7. We can ignite Na or Mg with a match. Why not coal or iron? 
8. What is meant by oxidation ? What by reduction ? 
9. Was P or Na acid or alkaline before oxidation? 
10. Why is NaOH called sodium hydroxide? 
11. What is the anhydride of an acid or alkali? 
12. What is formed when an acid neutralizes an alkali? 
13. Can you tell whether a compound is alkaline or not by its 
formula ? 
14. Why is the amount of H collected in the electrolysis of water 
slightly greater than twice the O ? 
15. Why are 03 and H202 chemically active substances ? 
16. Lime water, Ca(OH)2, turns green cloth yellow. How might 
the color be restored? 
17. What should be done when acid is spilled on clothing? 
18. What is an acid? What is a base? What is an alkali? What 
is a salt? 
LABORATORY QUESTIONS. 32 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
SULPHUR. 
Useful Data : Atomic Symbol, S ; Molecular Formula, S2; Va- 
lence, 2, 4 or 6 ; Atomic Weight, 32 ; Electro-negative. 
FORMS OF SULPHUR. 
66. Precipitated Sulphur. To half a test tube of water, 
add 1 g. of flowers of sulphur and g- of slaked lime. Boil 
and filter. Acidify the filtrate with HC1. Finely divided 
white sulphur is precipitated, called “milk of sulphur.” 
67. Crystalline Sulphur. Dissolve y g. of flowers of sul- 
phur in 5 c.c. of carbon disulphide, CS2. Set aside until 
evaporated, and examine the crystals. 
68. Plastic Sulphur. Melt io g. of roll sulphur in an 
evaporating dish until it is thick and dark. Pour it slowly 
into a bowl of cold water. Chew the plastic sulphur. It 
quickly turns to the crystalline variety. 
6g. Test for Sulphur. Sulphur heated on a silver coin 
forms a black stain of silver sulphide, Ag2S, which may be 
dissolved by potassium cyanide, KCy, solution. 
COMPOUNDS OF SULPHUR AND HYDROGEN. 
Hydrogen Sulphide, H2S. 
70. Preparation from Ferrous Sulphide. Prepare a gen- 
erator with an ignition jet. In it place several pieces of 
ferrous sulphide, FeS. Cover them with water and add a 
little sulphuric acid, H2S04. Note the odor of the gas 
evolved, and its action on moist blue litmus paper. Ignite SULPHUR. 
33 
the jet. Note that the rotten-egg odor changes to that of 
burning matches. Cold porcelain, pressed down on the 
flame, has sulphur deposited on it. 
Reactions—FeS-{-H2S04 = FeS04-f-H2S. 
h2s+3o=h2o+so2. 
71. Formation of Metallic Sulphides. Prepare solutions 
of Pb, Cu and Sb salts in separate test tubes. Pass hydro- 
gen sulphide, H2S, through each. Precipitates of insoluble 
metallic sulphides are formed. 
Reaction—Pb(N03)2-f-H2S = PbS-|-2HN03. 
72. Reducing Power of Hydrogen Sulphide. Pass H2S 
through a test tube of strong nitric acid, HN03. Sulphur is 
deposited. Repeat the process, using acid solutions of ferric 
chloride, FeCl3, and potassium chromate, K2Cr04. The 
colors change to those of reduced compounds. The hydro- 
gen unites with the O or Cl in each case. 
Reaction—2HN03-{-3H2S = 4H2C)-}-2N0-|-3S. 
73- Tests for Sulphides. 
1. The Lead Acetate Test. Paper moistened with lead 
acetate solution, Pb(C2H302)2, turns black when held in H2S, 
or dipped into a solution ot soluble sulphides. 
2. The Sulphuric Acid Test. Sulphuric acid, H2S04, on 
sulphides liberates H2S, as in 70. 
3. The Silver Test. A solid sulphide, mixed with sodium 
carbonate, fused on porcelain, cooled, placed on a bright silver 
coin and moistened with a drop of dilute HC1, yields a black 
stain of silver sulphide, Ag2S, soluble in potassium cyanide, 
KCy, solution. 34 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
COMPOUNDS OF SULPHUR AND OXYGEN. 
Sulphur Dioxide, S02. 
74. Preparation from Sulphur. Burn a little sulphur on 
the end of a match stick, and note the odor of S02. 
Reaction—S-{-02= S02. 
75. Preparation from Sulphuric Acid by Copper. Place 
strong sulphuric acid, H2S04, and copper turnings in a test 
tube. Heat until the white fumes of S02 arise. A moist 
wheat straw held in the gas will be bleached. 
Reaction—Cu-f-2H2S04 = CuS04-|-2H20-)-S02. 
76. Preparation from Sulphides. Heat on an iron plate a 
bit of lead sulphide, PbS (galena), or iron sulphide, FeS2 
(fool’s gold). Odors of S02 can be detected. 
Reaction—FeS2+202= Fe-|-2S02. 
77. Preparation from Water and Sulphur Dioxide. In a 
generator place some sodium sulphite, Na2S03, and add a 
little hydrochloric acid. S02 is evolved when strong acids 
are added to sulphites. Pass this gas through a test tube of 
water. Note the odor of the solution, its taste, and action 
on blue litmus paper. Save the solution for experiment 82. 
Sulphurous Acid, H2S03. 
Reaction—S02-fH20 = H2S03. 
78. Tests for Sulphites. 
1. The Acid Test. Treated with strong acids, sulphites 
liberate S02. 
2. The Barium Test. BaCl2 added to a solution of sul- 
phites, ppts. white barium sulphite, BaS03. Add HC1. SULPHUR. 
35 
BaS03 dissolves. Boil and filter1. Add HN03 and heat. 
Any dissolved BaS03 is oxidized to insoluble barium 
sulphate, BaS04, and precipitated. 
Sulphuric Acid, H0SO4. 
79. Dehydrating Effect. Use dilute sulphuric acid as ink, 
and write on paper. When dry warm over a flame and note 
the charred characters. Try other acids. 
Approximate Reaction— 
H2SO4 = C6-f 5H20-j-H2S04. 
80. Affinity for Water. In half a test tube of water pour 
concentrated sulphuric acid. Note the heat produced. In 
diluting H2S04, acid should always be added to water, not 
water to acid. 
81. Tests for Sulphates. 
1. The Barium Test. BaCl2 added to solutions of sulphates 
ppts. white BaS04, insoluble in boiling HC1. 
2. The Silver Test. Insoluble sulphates mixed with 
sodium carbonate, Na2C03, fused on charcoal, transferred to 
a bright silver coin, moistened with a drop of dilute acid, 
yield a black stain of Ag2S, soluble in potassium cyanide, 
KCy, solution. Compare 69 and 73-3. 
82. Illustrative Preparation of Sulphuric Acid. Take a 
test tube of freshly prepared H2SOi3, as in experiment 
77. Test it for H2S04 by 78-2, and set it away in an 
evaporating dish for some days, exposed to the air. No- 
tice that it loses its sulphurous odor, and the test shows 
Note i. There will nearly always be some BaSCH which is insoluble, and obscures 
the reaction, hence it is best to boil and filter. 36 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
H2S04 increasingly present. This illustrates slow oxi- 
dation. 
Reaction—2H2S03-f-02 = 2H2S04. 
83. Formation of Sulphates. Neutralize dilute H2S04 
with NaOH. Evaporate the solution to a small bulk. 
Cool, and examine the crystals of sodium sulphate, Na2S04, 
or Glauber’s Salt, formed. Note how iron and copper 
sulphates were formed in 70 and 75. 
Reaction—NaOH-|-H2S04 = Na2S04-{-H20. 
84. Tests for Thio-Sulphates—H2S203. 
1. The Hydrochloric Acid Test. HC1, added to a solution 
of thio-sulphates (so called hyposulphites), ppts. S with 
evolution of S02. 
2. The Silver Chloride Test. Freshly prepared AgCl, 28, 
is dissolved by a few drops of strong sodium thio-sulphate 
solution, forming a very sweet syrup. Hence the use of 
“hypo” in photography to dissolve silver from photo- 
graphic plates. 
LABORATORY QUESTIONS. 
1. Is sulphur soluble in water? 
2. How could a solution of S be made? 
3. Describe the changes observed in melting sulphur. 
4. Why do eggs discolor silver spoons ? 
5. Why is S deposited on porcelain in example 70? 
6. Volcanoes eject H2S and S02. Write the reaction showing why S 
is found in volcanic regions. 
7. When H2S water stands in the air S is precipitated. Write the 
reaction, explaining why sulphur water often contains specks of solid 
sulphur. 
8. Is H2S an acid ? What are its salts called ? 
9. Complete this equation : H2S-f-CuSC>4== 
10. Why are sulphide ores roasted in extracting the metals? NITROGEN. 
37 
11. What is fool’s gold? 
12. What are pyrites, and why so named? 
13. What per cent of S02 is S? 
14. Write the graphic formulas of HC1, H20, SO2 and H2S04. 
15. Write the reactions for each of the tests for sulphates. 
16. Analyze a piece of rubber, and report whether sulphides or sul- 
phates are present. 
17. How much S in 100 g. of H2SO4? 
18. What analogous compounds do S and O form ? 
19. How might calcium sulphate, CaS04, called gypsum, be prepared? 
20. Why should water not be poured into strong H2S04? 
21. Why are pocket match-safes not made of silver? 
22. Which sulphides are soluble and which insoluble? 
NITROGEN. 
Useful Data : Atomic Symbol, N; Molecular Formula, N2; 
Valence, 3 or 5; Atomic Weight, 14; Electro-negative; Specific 
Gravity, 0.971 (Airis 1). 
85. Preparation from the Air. Place a piece of phos- 
phorus the size of a pea on a cork, which is covered with a 
piece of asbestos1. Float this in a bowl of water. Ignite 
the P and cover it quickly with a beaker, well pressed down, 
so that no heated air escapes. When the action ceases, and 
the white fumes are all gradually dissolved in the water, 
cover the beaker with the hand or a glass plate, invert it and 
set it out, with the water it contains, on the desk. Quickly 
thrust in a lighted match, and note that the flame is ex- 
Note i. Phosphorus is kept under water. It must not be handled with the fingers, 
nor objects contaminated by it thrown where spontaneous combustion would be likely 
to cause a conflagration. 38 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
tinguished at the surface of the gas. Observe what fractional 
volume is occupied by water which was formerly occupied by 
oxygen. 
Reaction—2P -j- Os -f- N = P2Os -j- N. 
COMPOUNDS OF NITROGEN AND HYDROGEN. 
Ammonia, NH3. 
86. Preparation from Ammonium Chloride. Gently heat 
in a generator a mixture of equal parts of ammonium 
chloride, NH4C1, and quicklime, CaO, taking care not to 
break the generator. Test the gas evolved by moist red 
litmus paper. Pass it for some moments through ioc.c. of 
water, forming aqua ammonia. 
Reactions—2(NH4)Cl-j-CaO — CaC^-f-aNHg-j-HgO. 
nh3+h2o = nh4oh. 
87. Preparation from Animal Matter. In a test tube heat 
a few small pieces of hoof-parings from a blacksmith shop. 
Note the odor, and the power of the gas evolved to turn 
moist red litmus paper blue. 
88. Formation of Ammonium Salts. Neutralize some 
ammonium hydroxide NH4OH, or aqua ammonia, by 
adding HC1. Notice the white smoky fumes of ammonium 
chloride that arise. Evaporate the solution to a small bulk, 
and cool. Examine the crystalline ammonium chloride. 
89- Tests for Free Ammonia. 
1. The Lit7?ius Test. Moist red litmus paper is turned 
blue by the fumes of NH3. 
2. The Ammonium Chloride Test. A glass rod dipped in 
HC1 and held in NH3 yields white fumes of NH4C1. 
Reaction—NH40H + HC1 =NH4C1+H20. NITROGEN. 
39 
COMPOUNDS OF NITROGEN AND OXYGEN. 
Nitrous Oxide, N20, Laughing Gas. 
90. Preparation from Ammonium Nitrate. Heat some 
ammonium nitrate (NH4)N03in a generator. Nitrous oxide, 
N20, is evolved. Catch several test tubes of the gas by the 
displacement of water, as in 33. Note that the gas has a 
sweetish odor. Insert a match, and prove it a supporter of 
combustion. 
Reaction—NH4N 03 = N20-j-2H20 
91. Preparation from Nitric Acid by Copper. In a genera- 
tor gently warm a mixture of nitric acid, HN03, and copper 
turnings. Note the color of the gas evolved. Catch a test 
tube full of this gas by the displacement of water. Note that 
it is colorless. Expose it to the air, and it turns reddish 
brown by uniting with oxygen to form N204, a reddish gas, 
one of the higher oxides of nitrogen. 
Nitric Oxide, N202j or NO. 
Reactions—3Cu-j-8HN03= 
N2O2-I-O2 — N204. 
Nitrous Acid, HN02. 
92. Preparation of Nitrites from Nitrates. Heat some 
dry potassium nitrate, KN03, in a test tube. Oxygen is 
evolved, and potassium nitrite remains. Save this for the 
following tests. Nitrates thus readily yield oxygen. 
Reaction—2KN03 = 2KN02-f-02. 
93. Tests for Nitrites. 
1. The Starch Test. Solutions of nitrites acidulated with 
H2S04 turn blue a solution of starch-potassium-iodide 
mucilage (57, Note 1). 40 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
Nitric Acid, HN03. 
94. Preparation from Sodium Nitrate. Heat in a genera- 
tor equal quantities of sodium nitrate, NaN03, and H2S04. 
Catch 10 drops of the distillate in a test tube cooled by being 
wrapped in a wet cloth or immersed in a beaker of water. 
Put a drop of the acid on the finger nail and notice the yellow 
stain. Observe that it is strongly acid. 
Reaction —2NaN 03-j- H2S04 = N a2S04-f 2HNO3. 
95. Preparation of Gunpowder. Take 1 part of flowers 
of sulphur, 2 parts of powdered carbon, and 7 parts of potas- 
sium nitrate, KN03, or nitre. Dampen the mass. Grind it 
in a mortar and dry it. When dry, pulverize and ignite 
small quantities on an iron plate. 
Approximate Reaction— 
S -|- 2KNO3 -f- 4C = K2S 2CO2 -j- 2CO -}- N. 
96. Preparation of Nitro-hydrochloric Acid. Make a 
mixture of 1 part HNOg and 3 parts of HC1 in a test tube. 
Warm, and note the odor of chlorine liberated. Dissolve in 
this a scale of gold. This acid with metals forms chlorides, 
and its power is due to the liberation of nascent chlorine. 
97. Formation of Nitrates. Heat a bit of metallic silver 
with HN03. Dilute with water, and use the silver nitrate, 
AgN03, in testing for chlorides, as in 43. Note how cop- 
per nitrate was formed in 91. All nitrates are soluble in 
water. 
98. Tests for Nitrates. 
1. The Fei-rous Sulphate Test. Mix a little strong H2S04 
with a little fresh green ferrous sulphate solution, FeS04. 
Cool the mixture and overlay it, in a test tube, carefully with 
a solution containing nitrates. Tap the tube gently, and at NITROGEN. 
41 
the junction of the liquids a ring forms, usually brownish 
black, but sometimes violet, red or brown. 
2. The Indigo Test. Indigo solution is decolorized by 
free nitric acid. 
3. The Nitric Oxide Test. Any nitrate heated with H2S04 
and copper yields brownish red fumes of N02. 
LABORATORY QUESTIONS. 
1. From the experiments, what per cent of air was shown to be N? 
2. What is the difference between ammonia and ammonium? Aqua 
ammonue and ammonium hydroxide? 
3. What per-cent of NH;j is H ? 
4. How might thunder storms prepare ammonia in the atmosphere ? 
5. Why is nitro-hydrochloric acid called “aqua regia”? 
6. Why is ammonia called “spirit of hartshorn”? 
7. What are spirits of ammonia? 
8. Write the equation when ammonia burns in air. 
9. Is quicklime an alkali? Try it on moist red litmus paper. 
10. Complete the equation KOH-|-(NH4)Cl= 
11. In general, what distinctive difference is there in the action of 
H2S and HN03 on compounds ? 
12. How many pounds of HNO3 can be prepared from a ton of 
NaN03, or Chili saltpetre ? 
13. Why are nitrates more easily prescribed than chlorides? 
14. Complete and balance the equation N20-f-C=C02 
15. How might laughing gas be manufactured from nitric acid and 
ammonia ? Write the reactions in full. 
16. Why is ammonia called the volatile alkali ? 
17. What difference do you observe in the color of red litmus paper 
which has been dipped in a fixed alkali and dried, and that of a slip 
dipped in volatile alkali and dried? Explain. 42 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
PHOSPHORUS. 
Useful Data : Atomic Symbol, P; Valence, 1, 3 or 5 ; Atomic 
Weight, 31 ; Electro-negative. 
99. Two Forms. 
(1) Waxy phosphorus should be handled with forceps. 
It emits a garlic odor and fumes luminous in the dark. 
Heat a small piece in a test tube and it burns, emitting white 
fumes of phosphoric pentoxide, P2O5. 
(2) Red or amorphous phosphorus is not luminous nor 
poisonous. It is an allotropic form of phosphorus. Heat a 
small amount cautiously in the bottom of a test tube. Some 
of it may then be removed on the end of a glass rod, and 
found to be ordinary waxy phosphorus. 
ioo. Spontaneous Combustion. Dissolve a grain of waxy phos- 
phorus in a few drops of carbon disulphide, CS2. Pour the 
solution on a filter paper laid on a ring-stand. The paper 
will take fire after a few moments from the heat caused by 
the rapid oxidation of the phosphorus. 
ioi. Reducing Properties. Add a solution of phosphorus 
in carbon disulphide, CS2, to a solution of copper sulphate, 
CuS04. Shake the tube, and observe the formation of black 
metallic copper, copper phosphate, etc., due to the union of 
phosphorus with the oxygen of the CuS04. 
Phosphoric Acid, H:,P04. 
102. Preparation from Phosphorus. Place a small quantity of 
red phosphorus in an evaporating dish. Cover it with HN03. 
Warm gently until the phosphorus is dissolved. Evapo- PHOSPHORUS. 
43 
rate the solution to a thick syrup. This is nearly pure 
phosphoric acid, H3P04. 
Reaction—3P+5HNO34-2H2O = 3H3P04-[-5NO. 
103. Preparation from Phosphoric Oxide. Refer to experi- 
ment 63, and note the method of formation from P205 
and water. 
104. Formation of Phosphates. Neutralize some H3P04 
with sodium hydroxide, NaOH. Evaporate the solution 
nearly to dryness, and examine the sodium phosphate, 
Na2HP04, formed. 
105. Precipitation of Earthy Phosphates. Dissolve bone 
ash in dilute HC1. Render the solution alkaline with 
NH4OH, and note the precipitate of calcium phosphate, 
Ca3(P04)2. 
106. Tests for Phosphates. 
1. The Silver Test. AgN03 ppts. from neutral solutions 
of phosphates, yellow silver phosphate, Ag3P04, soluble in 
(NH4)OH and HN03. 
2. The Magnesium Test. A mixture, consisting of MgS04, 
(NH4)C1 and (NH4)OH ppts. white crystalline ammonio- 
magnesian phosphate, NH4MgP04. 
3. The Molybdate Test. Ammonium molybdate, (NH4)2- 
Mo04, ppts. from solutions of phosphates, acidulated with 
HNOa, yellow ammonium phospho-molybdate (NH4)3P04- 
(MoO3)10, which increases on application of heat and on 
standing. 
107. Tests for Hypophosphites. HgPC^.1 
Note i. Phosphates are all insoluble in neutral solution, except those of the alkali 
bases. Hypophosphites are nearly all soluble, and are thus easily administered. 44 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
1. The Silver Test. AgN03 ppts. in neutral solutions of 
hypophosphites white silver hypophosphite, AgH2P02, soon 
turning black from the reduction of metallic silver. 
2. The Mercury Test. HgCl2 ppts. from solutions of 
hypophosphites white mercurous chloride (calomel, HgCl), 
when warmed with HC1. 
108. Preparation of Sodium Pyrophosphate. Heat sodium 
phosphate, Na2HP04, in a test tube until the water of crys- 
tallization is given off. Gradually raise the tube to a red 
heat. Sodium pyrophosphate, Na4P207, is formed, which 
will differ from the original sodium phosphate by yielding a 
white ppt. with AgN03. 
Reaction—2Na2HP04 =Na4P207-l-H20. 
LABORATORY QUESTIONS. 
1. Is red phosphorus soluble in CS2 ? 
2. Why should oils not be given in phosphorus poisoning? 
3. What is spontaneous combustion? 
4. What is the anhydride of phosphoric acid? 
5. Give the formulas of three acids that may be respectively neutral- 
ized by 1, 2 and 3 atoms of Na. 
6. Why is H3PO4 said to‘be tribasic? How many different sodium 
salts can it form ? Give their formulas and the reaction of each salt to 
litmus paper. 
7. When earthy phosphates are in solution, what must be the reaction 
of the liquid ? 
8. When would urine precipitate calcium phosphate in the bladder? 
9. Give the graphic formula for H3PO4. 
10. Why are hypophosphites useful in medicine? 
11. Why is pyro-phosphoric acid so named? 
12. Why are “hypo” and “ortho” phosphoric acids so named? 
13. How may the latter two be distinguished by AgN03? 
14. Can there be one phosphate containing three distinct bases? 
15. How much P is contained in a pound of bone ash, 85% of which 
is Ca3(P04)2, and the remainder CaC03? 
16. What are microcosmic salts? BORON. 
45 
BORON. 
Useful Data : Atomic Symbol, B; Valence, 3 ; Atomic Weight, 
11 ; Electro-negative. 
BORIC OR BORACIC ACID, H3B03. 
109, Preparation from Borax. Make a hot saturated 
solution of borax, Na2B407. Add sulphuric acid until 
slightly acid. Cool, and collect the crystals of boric acid. 
Note that these crystals are soluble in glycerine. 
Reaction—Na2B407-]-H2S04-j-5H20 = Na2S04-f-4H3B03. 
iio. Borax Bead. Heat a small loop of platinum wire 
and dip it in powdered borax. Reheat and repeat the 
process until a glassy bead is obtained. Touch this with 
a tiny speck of cobalt compound and reheat. The bead 
becomes blue. Many metals may thus be distinguished by 
the color of the double salts formed with the borax bead. 
hi. The Flame Test for Boric Acid. Boric acid, or 
borates moistened with H2S04, dissolved in alcohol and 
the solution ignited, tinge the flame pale green. Best 
seen when the flame is gently blown by the breath. 46 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
CARBON. 
Useful Data : Atomic Symbol, C ; Valence, 4; Atomic Weight, 
12; Electro-negative. 
112. Forms of Carbon. Examine the prepared samples 
of graphite or plumbago, lamp black, bone black, char- 
coal, coke, gas carbon, peat, lignite, bituminous and anthra- 
cite coal. 
113. Reduction by Carbon. Mix a small quantity of 
powdered charcoal and copper oxide in a test tube. Heat 
the tube very hot and reduced, reddish metallic copper ap- 
pears. 
Reaction—2CuO-j-C = 2Cu-j-C02. 
114. Decoloration by Carbon. Arrange a funnel, fitted 
with a filter paper and half filled with bone black. Moisten 
this carbon with water, and through it filter a solution of 
any organic coloring matter, such as litmus, indigo or 
cochineal. The color is removed. Repeat with a mineral 
coloring matter, like potassium chromate, and observe that 
it is not removed. 
115. Deodorization by Carbon. Saturate some water with 
H2S until it smells strongly of the gas. Filter this through 
bone black, and note that the odor is entirely removed. 
CARBON AND HYDROGEN. 
Methane, CH4. 
116. Preparation from Sodium Acetate. Mix 2 g. of 
sodium acetate, Na(C2H302), which has been just pre- 
viously thoroughly dried, with 8 g. of NaOH and 2 g. of CARBON. 
47 
finely powdered quicklime, CaO. Heat this mixture very 
hot in a generator fitted with an ignition jet. Ignite the 
gas, which is methane, CH4, or marsh gas, the simplest of 
the many hydrocarbons, and the starting point in organic 
chemistry. 
Reaction—Na(C2H302)N-f-a0H = Na2C03-(-CH4. 
117. Preparation of Illuminating Gas. Half fill a clay 
pipe bowl with powdered bituminous coal. Lute the top 
of the bowl with wet clay or a freshly mixed plaster paris 
paste. Heat the bowl very hot, and at last ignite the gas 
at the end of the stem. Note the water given off and the 
coal tar produced. The vapor will turn moist red litmus 
blue, showing the presence of ammonia. At the end of 
this “destructive distillation ” open the pipe and examine 
the coke formed. 
CARBON AND OXYGEN. 
Carbon Monoxide, CO. 
118. Preparation from Oxalic Acid. Put 5 grams of 
crystallized oxalic acid in a test tube and cover it with 
H2S04. Strongly heat the tube. After a moment the 
escaping carbon monoxide, CO, may be ignited at the 
mouth of the tube, and burns with a characteristic blue 
flame. 
Reaction—C2H204-j-H2S04 = H2S04-}-C02-f-H20-(-C0. 
Carbon Dioxide, C02. 
119. Preparation by Combustion. Shake some lime water 
in a large test tube, and see that it remains clear. Hold 
a burning match in the tube until it is extinguished. 48 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
Close the tube with the thumb and shake it. Observe 
that the lime water becomes milky. 
Reaction—C-)-0 = C02, 
and 
CO-j-2Ca(OH)2 = CaCOg-f H20. 
120. Preparation from Carbonates. In a generator cover 
small pieces of marble, CaC03, with dilute HC1. Collect 
the heavy gas flowing from the delivery tube in a beaker, 
as though it were water. Insert a blazing match. Observe 
that it is extinguished at the surface of the gas. Pour 
some of this carbon dioxide, C02, into a tube containing 
lime water, shake, and confirm the presence of CG2. 
Reaction—CaC03-f-2HCl = C02-fCaCl2-f-H20. 
121. Preparation by Fermentation. At the close of the 
laboratory period place in a generator a dilute solution of 
molasses and a piece of yeast. Set it in a warm place 
and let the delivery tube dip in a test tube of clear lime 
water. The next day the lime water will be turbid from 
C02 given off. 
Sugar. Alcohol. 
Reaction—C6H1206 = 2(C2H5)0H-|-2C02. 
122. Detection of C02 in the Breath. Blow the breath 
through a test tube of dilute lime water. The calcium 
carbonate, CaC03, first formed will later redissolve. This 
precipitate will again fall when the solution is boiled, and 
the C02, which holds the limestone in solution, escapes. 
123. Preparation of Carbonic Acid. Pass C02, from the 
generator prepared in the hood, through a test tube of 
water. The resulting solution turns blue litmus proper 
faintly red. Carbonic acid, H2C03, is probably formed. CARBON. 
49 
When this is neutralized by NaOH, sodium carbonate, 
Na2C03, is produced. 
Reactions—C02 -(- H20 = H2C03. 
H2C03 -f 2NaOH = Na2C03 + 2H20. 
124. Test for Carbonates. Any carbonate treated with 
HC1 effervesces and liberates C02, which may be detected by 
passing the gas through lime water and noting any turbidity. 
CARBON AND SULPHUR. 
Carbon Disulphide, CS2. 
125. Determination of Composition. Place a few drops 
of carbon disulphide in a bottle. Ignite it by inserting 
a glass rod heated to redness at the end. Note the odor 
of S02 arising, proving the presence of sulphur. When 
action ceases, shake the contained gas with a little lime 
water. Observe the turbidity as a proof of the presence 
of C. 
Reaction—CS2 + 302= C02 -|- 2S02. 
126. Solvent Power. Dissolve in CS2 small amounts of 
S, rubber, oil and paraffin. Remove a grease stain from 
cloth with CS2. 
CARBON AND NITROGEN. 
Hydrocyanic Acid, HCN, or HCy. 
127. Preparation from a Cyanide. Place a pinch of po- 
tassium cyanide, KCy, in a test tube. Cover it with 
dilute H2S04, warm, and note the odor of hydrocyanic 
acid, HCy, or Prussic acid, like the odor of peach blooms. 
Reaction—2KCy -f- H2S04 = K2S04 -j- 2HCy. 
128. Preparation from a Ferrocyanide. In a generator 
place 1 g. of potassium ferrocyanide, K4FeCy6, and cover 50 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
it with dilute H2S04. Gently heat the generator and pass 
the gas formed into a test tube of water. Dilute hydro- 
cyanic acid, HCy, is formed. Save this for the following 
tests. 
Reaction— 
2K4FeCy6 -f- 6H2S04 = 6KHS04 -j- Fe2K2Cy6 -)- 6HCy. 
129. Tests for Cyanides. 
1. The Silver Test. AgN03 ppts. from solutions of 
cyanides (except mercuric cyanide) white silver cyanide, 
AgCy, insoluble in dilute HN03, soluble in NH4OH, 
recognized from silver chloride by evolving the odor of 
HCy when treated with strong HC1 (see 43). 
2. The Prussian Blue Test. To a solution of cyanides 
a few drops of KOH and FeS04 are added, and the 
mixture warmed, then two drops of FeCl3 are added. 
The whole is slightly acidulated with HC1, to dissolve 
ferrous and ferric hydroxides, when Prussian blue, Fe4- 
(FeCy6)3, will appear. 
3. The Sulphocyanate Test (a). To a solution of cya- 
nides, add 2 drops of yellow ammonium sulphide, 
(NH4)2S2. Warm until colorless. Slightly acidulate with 
HC1, when a drop of FeCl3 will yield a blood-red colora- 
ation. This is the most delicate test. 
(h) This test may be thus performed: Place in a 
beaker the material containing free HCy (if a cyanide, 
free HCy must be liberated by adding H2S04). Cover 
the beaker with a glass on the under side of which are 
two drops of (NH4)2S2. With this the vapor forms 
ammonium Let the drop dry thoroughly. 
If HCy were present, the spot immediately turns blood- 
red when touched with a solution of FeCl3. CARBON. 
51 
1. How might cider vinegar be rendered white, like wine vinegar? 
2. Write the reaction when iron ore, Fe203, is mixed with coke to 
obtain pig iron. 
3. Write the reaction showing how H2S water was deodorized. 
4. Write the reaction involved when “fire-damp” burns. 
5. What is destructive distillation? 
6. Write the reaction occurring when limestone is heated. 
7. How is the C02 of the breath formed? 
8. C02 contains O. Why does it not support combustion? 
9. The yeast plant uses neither alcohol nor C02. For what purpose 
does it split the sugar into these substances? 
10. Why is NaHC03 called bicarbonate or acid carbonate of soda? 
Is it acid? 
11. What other substances beside CS2 will dissolve grease? 
12. What is soda water, and how may it be prepared? 
13. Name several elements that exist in allotropic forms. 
14. Bone-black contains principally C, CaC03, Ca3(P04)2, and tarry 
organic compounds. How may the C be obtained pure for filters? 
15. If a ton of C is burned, what weight of C02 is produced? 
16. Does wood produce as much heat during decay as during com- 
bustion ? 
17. Where was the C, now contained in coal, before the carbon- 
iferous age? 
18. What causes beer to foam? 
19. Explain the cause of a non-luminous Bunsen flame. 
20. Why does burning alcohol, (C2H5)OH, not deposit soot? 
21. Why do stoppers in KOH or NaOH bottles stick when left for 
some time? Touch the neck of one with HC1, and observe the phe- 
nomena. 
22. Of what are oyster shells composed? Test one for carbonates. 
23. Why is KCy used in extracting gold ? 
24. Why was CaO used in the preparation of methane ? 
25. How can a chloride be distinguished from a cyanide byAgN03? 
26. Write the reaction showing how borax is a salt of tetraboric acid. 
27. How may the NH3 given off in gas manufacture be utilized ? 
28. What are the blue flames seen in a stove burning anthracite coal ? 
29. Why do kettles have crusts deposited within them ? 
LABORATORY QUESTIONS. 52 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
TABLE I. 
Preliminary Tests for Common Acids. 
I. THE SUBSTANCE IS A SOLID. 
Place a small portion in a test tube, add i c.c. of con- 
centrated H2S04, and warm gently. 
A. Effervescence of a colorless gas. 
1. Odorless. Carbonates, 124; Oxalates, 213. 
2. Odor of rotten eggs. Sulphides, 73. 
3. Odor of burning sulphur. Sulphites, 78; Thio- 
sulphates, 84. 
4. Odor of peach bloo?tis. Cyanides, 129. 
5. Odor of vinegar. Acetates, 209. 
6. Odor merely irritating. Nitrates, 98 ; Chlorides, 
43 ; Fluorides, 53. 
B. Effervescence of a colored gas. 
1. Violet color. Iodides, 52. 
2. Yellowish brow?i color. Acrid odor, Bromides, 49. 
3. Reddish brown color. Nitrous odor, Nitrites, 93. 
4. Greenish yellow color. Chlorine odor, Hypo- 
chlorites, 166. 
5. Greenish yellow color. Chlorine odor, with de- 
tonation, Chlorates, 45. 
C. No action. 
Test for H2S04, 81; H3P04, 106; HNOs, 98, etc. 
II. THE SUBSTANCE IS A LIQUID. 
Neutralize a portion, evaporate it to dryness, and test 
the residue by I. TABLE II. 
53 
Barium Chloride. 
Calcium Chloride. 
Silver Nitrate. 
Ferric Chloride. 
Not Precipitated. 
Precipitates White. 
Precipitates White. 
Precipitates. 
Precipitates. 
i. Insoluble in HCl. 
1. Soluble in much 
1. Soluble in Dilute 
Carbonates, reddish, 
Test original solu- 
Sulphates, 81. 
H 2 O. 
HNO3. 
124. 
tion. 
Sulphates, 81 • 
Borates, white, in. 
Nitrites, 93. 
2. Effervesce with 
2. Soluble in NH^Cl. 
Carbonates, white, 
Borates, yellowish, 
Acids. 
Borates, in. 
III. 
Nitrates, 98 
Carbonates, 124.. 
Sulphites, 78. 
Carbonates, 124. 
Citrates, 215. 
3. Insoluble in Acetic 
Phosphates, yellow, 
106. 
Sulphites, white, 78. 
Oxalates, yellow, 213. 
Chlorates, 45. 
3. Char when Heated 
on Platinum. 
Acid. 
Oxalates, 213. 
Tartrates, white, 214. 
Citrates, white, 215. 
Phosphates, yellow- 
ish, 106. 
Tartrates, 214. 
Tartrates (slightly), 
Citrates, 215. 
2I4« 
Sulphates (slightly), 
81. 
2. Insoluble in Dilute 
HNO3. 
Sulphides, black, 73. 
4. Not Distinguished. 
4. Char when Heated 
Chlorides, white, 43 
Cyanides, white, 129 
Oxalates, 213. 
on Platinum. 
Bromides, white, 49. 
Phosphates, 106. 
Tartrates, 214. 
Iodides, yellow, 52, 
Borates, hi. 
Citrates, 215. 
Sulphides, black, 73 
A. The Substance is Soluble. Make a strong solution of a small portion. Boil it with a strong 
solution of Na2C03. If no ppt. occurs, no interfering bases are present. Make a solution, exactly 
neutralize, if necessary, and proceed by the table. If a ppt. occurs, proceed by B. 
B. The Substance is Insoluble. Boil part of the powdered substance wTith a strong mixture of 
KOH and Na2C03 solutions. Cool and filter. The filtrate contains all the acids present in the 
original substance now in the form of soluble potassium or sodium salts. Exactly neutralize 
with HNO3. Boil and concentrate, if dilute. Apply each of the following reagents to very small 
portions. Any ppts. formed will lead to the detection of the acids by the tests referred to. 
A Table to Aid in the Detection of the More Important Acids. 
TABLE II. THE MORE 
IMPORTANT REACTIONS 
ANALYTICAL AND SYNTHETICAL 
OF THE PRINCIPAL 
MEDICINAL METALS. THE METALS. 
57 
THE METALS. 
THE FIVE METALLIC GROUPS. 
GROUP I. THE SILVER GROUP. 
Ag, Pb and Hg(ous). 
130. Group Precipitant, HC1. Prepare a solution of the 
salts of each of these three metals in a separate test tube. 
Add a few drops of HC1 to each, and note the white 
precipitates. 
Hg(ic), Pb, Bi, Cu — As, Sb (Cd, Sn, Pt, Au) 
GROUP II. THE COPPER GROUP. 
131. Group Precipitant, H2S in Acid Solution. Prepare a 
solution of the salts of each of these six metals in sepa- 
rate test tubes. Add a drop of HC1 to each; no precipi- 
tate falls. Pass H2S gas through each. Note the colors 
of the various sulphides precipitated. 
GROUP III. THE IRON GROUP. 
Fe, Al, Zn (Cr, Mn, Ni, Co). 
132. Group Precipitant (NH4)2S in Alkaline Solution. Prepare 
a solution of the salts of each of these three metals in a 
separate test tube. Add first a few drops of NH4OH to 
each, and follow with a solution of (NH4)2S. Note the 
color of the precipitated Fe and Zn sulphides and Al 
hydrate. 
GROUP IV. THE BARIUM GROUP. 
133. Group Precipitant, (NH4)oC03 in Alkaline Solution. Pre- 
pare a solution of the salts of each of these two metals 
Ba, Ca (Sr). 58 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
in a separate test tube. Add first a few drops of NH4OH 
to each, and follow with (NH4)2C03. Note the white 
precipitates. 
GROUP V. THE POTASSIUM GROUP. 
134. Group Precipitant, None. Prepare solutions of these 
salts, and note that they are precipitated by none of the 
preceding group reagents. 
Mg, K, Na, NH4 (Li). 
1. Test bottles Nos. 1, 2, 3, 4 and 5, and determine to which 
group the one salt dissolved in each belongs. 
LABORATORY EXERCISES. 
ANALYTICAL REACTIONS OF GROUP I, 
135. Silver—Ag'.— Confirm reactions, using Solution of 
AgNO3. 
1. HC1 ppts. white AgCl, soluble in NH4OH. 
2. K2Cr207 ppts. red Ag2Cr04. 
3. H2S ppts. black Ag2S. 
4. KI ppts. pale yellow Agl. 
5. NH4OH ppts. black Ag20, soluble in excess. 
6. NaOH ppts. brown Ag20, soluble in (NH4)OH. 
7. Solids heated with Na2C03 on charcoal, in the re- 
ducing blowpipe flame, yield bright metallic beads, solu- 
ble in HN03. 
136. Lead, Pb".— Confirm reactions, using solution of 
Pb{C2H,Ofi>2. 
1. HC1 ppts. white PbCl2, soluble in hot water and 
strong acids. 
2. KI ppts. bright yellow Pbl2. 
3. H2S ppts. black PbS. 
4. KOH ppts. white Pb(OH)2, soluble in excess. THE METALS. 
59 
5. H2S04 ppts. white PbS04, in dilute solutions only 
on standing. 
6. K2Cr207 ppts. bright yellow PbCr04. 
7. Solids heated with Na2C03 on charcoal, in the re- 
ducing blowpipe flame, yield soft metallic beads, with a 
yellow incrustation of PbO on the charcoal. The beads 
are soluble in HN03. 
137. Mercury (ous),Hg".—Confirm reactions, using solution of 
HgNO^ 
1. HC1 ppts. white HgCl (calomel), blackened by 
(NH4)OH. 
2. KI ppts. dark green Hgl. 
3. H2S or (NH4)2S ppts. black Hg2S. 
4. Bright copper, in a slightly acid solution, becomes 
covered with metallic Hg, made bright by rubbing. 
LABORATORY QUESTIONS ON GROUP I. 
1. Name the three insoluble chlorides. 
2. What is a group precipitant? 
3. How may silver nitrate be prepared? 
4. How might one prepare lead acetate? 
5. Why are silver salts used in photography? 
6. Write the reaction 2AgN03 + 2NaOH = 
7. Why is MgS04, or Epsom salt, an antidote in acute lead poisoning? 
8. With what acid could Pb be dissolved from an ore ? 
9. Why does lead acetate added to tap water give a precipitate? 
10. Try to dissolve silver stains from the hand with KCy. 
11. Why is AgNOs an ingredient of indelible ink? 
12. Make a solution containing salts of Group I. Turn to the analyti- 
cal Table, III, page 77, and separate each metal. 
13. Test solutions 1, 2, 3, 4, 5 and 6 on the side table, reporting the 
metals found in each. 
14. Test ores A, B, C and D for first group metals by powdering the 
ore, dissolving in HNO3, filtering, neutralizing excess of acid, and pro- 
ceding by Table III. Report the metals found. 60 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
ANALYTICAL REACTIONS OF GROUP II. 
138. Mercury(ic), Hg7/. —Confirm reactions, usmg solution of 
HgCl2. 
1. H2S ppts. ultimately black HgS, soluble in aqua 
regia, insoluble in (NH4)2S. 
2. SnCl2 ppts. white HgCl, turning black with liberation 
of minute globules of Hg, which appear when the ppt. is 
boiled with HC1 and rubbed. 
3. (NH4)OH ppts. white (NH2)HgCl (white precipitate). 
4. KOH ppts. yellow HgO. 
5. KI ppts. bright red Hgl2. 
6. All mercury compounds sublime when heated, and 
yield reaction 4 under mercurous salts. 
7. All mercury salts heated in a test tube with Na2C03 
give a mercury mirror. 
139. Bismuth, — Confirm reactions, using solution of 
BiClz. 
1. H2S ppts. black Bi2S3, soluble in HN03, insoluble in 
(NH4)2S. 
2. H20 ppts. white basic BiOCl, when the solution with 
HC1, evaporated nearly to dryness, is poured into much 
water. The ppt. is insoluble in tartaric acid (compare 
Sb test, 142-4). 
3. KOH or (NH4)OH ppts. white Bi(OH)3, insoluble in 
excess, becoming yellow Bi203 on boiling. 
4. K2Cr04 ppts. yellow Bi2(Cr04)3, soluble in HN03, 
insoluble in NaOH. 
140. Copper, Cn//.— Confirm reactions, using solution of CuSO4. 
1. H2S ppts. black CuS, soluble in HN03 and KCy, 
insoluble in (NH4)2S. 61 
THE METALS. 
2. NH4OH ppts. greenish blue basic salts, soluble in 
excess to a dark blue solution of a double salt of copper and 
ammonium. 
3. KOH or NaOH ppts. pale blue Cu(OH)2, insoluble in 
excess? 
4. K4FeCy6 ppts. brown Cu2FeCy6, insoluble in dilute 
acids, decomposed by KOH. 
5. A bright steel needle dipped in a slightly acid solution 
of a copper salt becomes covered with metallic copper. 
6. Cu salts moistened with HC1 and heated in a Bunsen 
flame tinge it green. Solutions of Cu are always blue or 
green. 
7. Solids fused with Na2C03TKCy on charcoal, before 
the reducing blowpipe flame, yield bright red metallic beads, 
soluble in HN03. 
141. Arsenic, As7".— Confirm reactions, using solution of 
1. H2S ppts., from acid solution, yellow As2S3, soluble in 
(NH4)2S, KOH, NH4OH and HN03, nearly insoluble in 
hot HC1 (compare Sb, 142-1). When As is in the form of 
arsenic acid, H3As04, it must first be reduced to arsenous 
acid, H3As03, by heating with HC1 and Na2S03. 
2. Alkalies produce no ppt. 
3. AgN03 ppts. from neutral solutions pale yellow 
Ag3As03. To a solution of As203 forming arsenous acid, 
H3As03, add a few drops of AgN03. Touch the surface of 
the solution with a glass rod moistened with dilute (NH4)OH. 
The yellow Ag3AsOs forms. With arsenic acid, the ppt. is 
chocolate color (151). 
4. Marsh's Test. Fit a generator with a bent ignition jet 
and thistle tube, like the one on the demonstration desk. In 62 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
it generate H from pure zinc, water and H2S04. Observe 
the usual precaution and light the jet. The flame leaves no 
spot when cold porcelain is pressed in it, and no stain forms 
on the jet when the tube is heated to a dull redness by a 
Bunsen burner. Through the thistle tube add a few drops 
of an arsenic solution. Spots may now be deposited on 
porcelain, and a mirror on the tube when heated. 
Tests for Arsenic Spots. 
(a) They dissolve in a solution of bleaching powder. 
They turn yellow, touched with (NH4)2S and evapo- 
rated. The residue is insoluble in HC1, soluble in 
NH4OH. 
(V) They dissolve in HNOg, and when this is evaporated 
and touched with AgN03 and NH4OH and again evaporated, 
a brick-red spot remains (arsenic acid, 141-3). 
Tests for Arsenic Mirror. Cut out a section of the tube 
containing the mirror, so that about 3 inches of clean tube 
extends beyond the stain. Hold the tube at an angle. 
Gently heat the mirror and drive the As into the clean 
portion of the tube. It will be deposited as As203, seen 
under the microscope as octahedral crystals. These may 
be dissolved in 10 drops of hot water and tested by 141-3, 
or acidulated and tested by 141-1. 
5. Reinsch's Test. Bright copper boiled with an acid 
solution of arsenic will be coated with metallic arsenic. 
Fold this up and heat it in a glass tube open at both 
ends. The As sublimes as As203, which may be detected 
by the microscope as octahedral crystals. These may be 
dissolved in H20 and tested by 141-1 and 3. 
This test is a delicate and useful one, as it is unim- 
paired in solutions containing organic matter. Arsenates 
act more slowly than arsenites. Antimony and mercury both give a deposit on copper, but Sb sublimes as an 
amorphous powder and Hg as minute metallic globules. 
6. Solids heated in a tube with carbon, or K4FeCy6, or 
a mixture of Na2C03 and KCy, deposit metallic As on the 
sides of the tube. 
7. Metallic As heated on charcoal burns, yielding copi- 
ous white fumes of As203, having a garlic odor. 
THE METALS. 
63 
142. Antimony, Sb^'.— Confir?7i reactions, using solution of 
Tartar Emetic. 
1. H2S ppts. orange Sb2S3, soluble in (NH4)2S, KOH, 
and hot concentrated HC1 (compare As, 141-1), insoluble 
in NH4OH. 
2. KOH ppts. Sb203, soluble in excess. 
3. NH4OH ppts. Sb203, insoluble in excess. 
4. Solutions concentrated with addition of a few drops 
of HC1 and poured into water ppts. white SbOCl, soluble 
in tartaric acid (compare Bi, 139-2). 
5. Marsh's Test. Performed like test 141-4, for arsenic. 
Tests for Antimony Spots. 
(<z) They are insoluble in a solution of bleaching powder. 
(h) They turn orange when touched by (NH4)2S, and 
evaporated. The orange spots are insoluble in (NH4)OH, 
but soluble in HC1. 
(c) They dissolve in HN03, but yield no red color with 
AgNOa and NH4OH (compare, 141-4, c). 
Tests for the Antimony Mirror. It is often blacker 
than the As mirror, and yields no crystals under the mi- 
croscope when treated as directed under As. The white 
amorphous residue is insoluble, and the attempted solution 
does not vield tests with AerNOo or H0S, as under arsenic. 64 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
6. Solids fused with Na2C03 on charcoal, before the 
reducing blowpipe flame, yield brittle metallic globules of Sb 
and white incrustations of Sb203. 
SOME IMPORTANT SYNTHETICAL REACTIONS OF GROUP II. 
143. Preparation of Bismuth Nitrate and Sub-Nitrate. Dissolve a 
little powdered metallic Bi in a few drops of HN03. Bismuth nitrate 
Bi(N03)3 is formed. Pour this into a beaker of water. Bismuth sub- 
nitrate is precipitated. 
Reaction—Bi(N03)3+H20—BiON03+2HNO:;. 
144. Preparation of the Two Mercury Nitrates. 
(a) Mercurous Nitrate. Heat a globule of Hg with 2 drops of HN03. 
Hg is in excess, and mercurous nitrate, HgN03, is formed. Dissolve 
this in a little distilled water, and save for 145. 
(b) Mercuric Nitrate. Heat the Hgas above with more HN03 than 
is required to dissolve it. Mercuric nitrate, Hg(N03)2, is formed. Dis- 
solve in distilled water, and save for 145. 
145. Preparation of the Two Mercury Iodides. 
(a) Mercurous Iodide. To the HgN03 formed above, add KI. A 
yellowish green ppt. of yellow mercurous iodide, Hgl, falls. 
(h) Mercuric Iodide. To the Hg(N03)2 formed above, add KI. A 
bright red ppt. of red mercuric iodide, Hgl2, falls. 
146. Preparation of the Two Mercury Oxides. 
(a) Mercurous Oxide. To calomel, HgCl, add a solution of KOH, 
or Ca(OH)2. Black mercurous oxide, Hg202, is formed. 
(b) Mercuric Oxide. To a solution of mercuric chloride, HgCl2, 
add KOH, or Ca(OH)2. Yellow mercuric oxide, HgO, falls. Heat a 
few grains of Hg(N03)2 in a test tube until fumes cease. The red 
mercuric oxide, HgO (red precipitate), remains. 
147. Preparation of the Two Mercury Chlorides. 
(a) Mercurous Chloride. Heat in a test tube equal parts of finely 
powdered dry NaCl and mercurous sulphate, Hg2S04. Calomel, HgCl, 
sublimes in the cool part of the tube. Tested by NH4OH, it turns black. 
(b) Mercuric Chloride. Repeat the above experiment, using mer- THE METALS. 
65 
curie sulphate, HgS04. Mercuric chloride, HgCl2, or corrosive sublimate, 
sublimes. It is tested by dissolving some in water and adding H2S. A 
black ppt. of HgS falls. 
148. Test for Corrosive Sublimate in Calomel. By the above processes 
the products are usually mixed. Calomel is insoluble, HgCl2 is soluble. 
Boil the suspected calomel, filter and pass ;H2S through the filtrate. A 
black ppt. indicates HgCl2, by the formation of HgS. 
149. Formation of Arsenous Acid. Note that As203 dissolves slowly 
in cold water, faster in hot. and also when HC1 or alkalies are added. 
Reaction—As203+3H20=2H3As03, or arsenous acid. 
150. Preparation of Fowler’s Solution, Boil a grain of As203 with 
water containing a little K2C03, and filter if necessary. This solution 
of potassium arsenite, KH2As03, colored with compound tincture of 
lavender and diluted to 1% of As, is Fowler’s Solution. Only alkali arsen- 
ites are soluble. 
151. Preparation of Arsenic Acid. Dissolve a little As203 in water, 
forming arsenous acid. Filter and divide into two parts. Boil one part 
nearly to dryness, with a little strong HN03, which will oxidize arsenous 
acid, H3As03, to arsenic acid, H3As04. Arsenous acid, on addition of 
AgN03 and neutralizing with NH4OH, yields a yellow ppt., while 
arsenic acid yields a chocolate ppt., 141-3. Arsenous acid is also oxidized 
to arsenic acid by heating thus with KC103 and HC1. Arsenic acid is 
reduced to arsenous acid by the addition of Na2S03 and HC1, when S02 
is liberated. 
152. Preparation of Tartar Emetic. Precipitate a solution of SbCl3 
with Na2C03. Boil the well-washed ppt. Sb203 with an equal weight of 
cream of tartar in solution. Evaporate, and collect the crystals. 
Reaction-SboO3+KH(C4H4O6)=2K(SbO)(C4H4O0)+HoO. 
1. How many of the sulphides of the copper group are soluble in 
(NH4)2S? 
2. Why does Pb appear in the second group ? 
3. Why does Hg appear in the second group? 
4. What difference is there in the addition of KOH and (NH4)OH to 
copper solutions ? 
LABORATORY QUESTIONS ON GROUP II. 66 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
5. How does bleaching powder distinguish between As and Sb ? 
6. Which contains the more acid, mercurous or mercuric nitrate? 
7. How might one detect pickles turned green by copper? 
8. Give the formulas for arsenous and arsenic acids. Which is the 
more common? 
9. Is there any difference in Valence in Hg(ous) and Hg(ic) com- 
pounds ? 
10. Write the reaction when CuO is heated with C. When As203 is 
heated with C. 
11. H3As03+Na0H= ? Complete and balance. 
12. What is an amalgam? 
13. Why is calomel apt to contain corrosive sublimate ? 
14. Why is Reinsch’s test useful ? 
15. What are the substances called red and white precipitates? 
16. Write the reaction involved in the formation of mercuric chloride, 
as prepared above. 
17. What substance would one get from a druggist if arsenic were 
called for? 
18. What substance would one get from a druggist if antimony were 
called for? 
19. Is there a difference in solubility among the varieties of white 
arsenic ? 
20. When a dime is dissolved in HN03, what evidence is there that it is 
an alloy of Cu ? 
21. Make a solution of CuS04, Pb(N03)2, Bi(N03)3, HgCl2, As203 
and K(SbO) (C4H4O6), acidulate with HC1, precipitate the sulphides, and 
separate by Table III, page 77. 
22. Make a solution of the first two groups, containing AgN03, PbN03 
and CuS04. Turn to the table, and separate and identify each metal. 
23. Examine bottles 7, 8, 9, 10, 11 and 12, on the side table, for metals 
of the first two groups, and report the metals in each. 
24. Dissolve 'in HNO3 the metals E, F, G and H, filter, nearly neu- 
tralize, separate by the table, and report the metals of the first two 
groups found. 
ANALYTICAL REACTIONS OF GROUP III. 
153- Iron(ous) Ft''.—Confirm reactions, using solution of Fe 
i. NH4OH ppts. Fe(OH)2, white when pure, usually dirty 67 
THE METALS. 
green from the presence of ferric salts, gradually turning, by 
absorption of O, to reddish brown ferric hydroxide, Fe(OH)3. 
2. (NH4)2S ppts. black FeS, soluble in HC1, insoluble in 
alkalies. 
3. (NH4)2C03 ppts. white FeC03, soluble in the pres- 
ence of free C02. 
4. Tannic acid and tannates ppt. black iron tannate. 
5. Ferrous salts are oxidized to ferric salts, slowly by 
standing, rapidly by heating with oxidizing agents, HN03, 
KC103, etc. 
154. Iron(ic), Fer//.— Confirm reactions, using solution of Fe Cl3. 
1. NH4OH or KOH ppts. reddish brown Fe(OH)3, in- 
soluble in excess. 
2. (NH4)2S ppts. black FeS mixed with S, soluble in 
HC1 and HN03. 
3. H2S, in acid solutions, ppts. S and reduces “ic” to 
“ ous ” iron. 
4. KCyS, K3FeCy6 and K4FeCy6 have the following reac- 
tion on “ous” and “ic” iron salts: 
Reagent. 
Ferrous Salts 
Ferric Salts. 
KCyS. 
K3FeCy6. 
Ka FeCys. 
No change. 
Dark blue ppt. Fe3(FeCy3)2. 
Pale blue ppt. (K2Fe)(FeCy3). 
Red solution Fe(CyS)3. 
No ppt. Reddish brown solution. 
Dark blue ppt. Fe4(FeCye)3. 
155- Aluminum, Al///.— Confirm reactions, using solution of 
AlfSOf)z. 
1. KOH and (NH4)OH ppt. white Al(OH)3, soluble in 
excess, but re-pptd. by the addition of ammonium salts. 
2. (NH4)2S ppts. white Al(OH)g. 
3. Na2HP04 ppts. white A12(P04)2. 
4. Solids fused on charcoal by the blowpipe, moistened 
with CoCl2 and reheated, yield an infusible blue mass. 68 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
156. Zinc, Zn7/.—Confirm reactions, using solution of ZnSO±. 
1. (NH4)2S ppts. white ZnS, soluble in acids. 
2. KOH ppts. white Zn(OH)2, soluble in excess, reprer 
cipitated on boiling. 
3. (NH4)OH ppts. white Zn(OH)2, soluble in slight 
excess. 
4. Na2C03 ppts. white basic carbonate. 
5. Solids fused with Na2C03 on charcoal, in the reducing 
blowpipe flame, become incrusted with ZnO, yellow while 
hot, white when cold. 
6. Solids fused on charcoal with the blowpipe, and 
moistened with CoCl2 and reheated, yield an infusible green 
mass. 
SOME IMPORTANT SYNTHETICAL REACTIONS OF GROUP III. 
157. Preparation of the Two Iron Sulphates. 
(a) Ferrous Sulphate. Dissolve iron filings or small nails in dilute 
H0SO4 until all action ceases. Filter, evaporate to small bulk and 
crystallize the green ferrous sulphate, FeS04, or iron proto sulphate. 
(b) Ferric Sulphate. Dissolve 6 parts by weight of FeS04 in water, 
and add 1 part of H2S04. Heat the mixture and drop in HNO3 until the 
black color first formed disappears. The resulting solution contains 
ferric sulphate Fe2(S04)3 or ferric tersulphate. When less acid is used 
the solution contains basic ferric sulphate, Fe40(S04)5. 
Reaction—6FeS04+3H2S04+2HN03=3Fe2(S04)3+2N0-f4H20. 
158. Preparation of the Two Iron Chlorides. 
(a) Ferrous Chloride. Dissolve iron filings in HC1 until action 
ceases. Filter, evaporate and crystallize the ferrous chloride, FeCl2. 
(b) Ferric Chloride. Acidulate a solution of FeCl2 with HC1, heat 
and add HNO3 until the black color first formed disappears. The 
resulting fluid is a solution of ferric chloride, FeCl3. 
Reaction—6FeCl24-2HN03+6HCl=6FeCl3+2N0+4H20. 
159- Preparation of Ferrous Iodide. Heat a few crystals of iodine with 
iron filings and water in a test tube. When the iodine has disappeared, THE METALS. 
69 
filter the greenish solution. On evaporation the solid ferrous iodide, 
FeCl2, remains. 
160. Preparation of Ferric Acetate. Precipitate a solution of FeCl3 
with NH4OH and wash the precipitated Fe(OH)3. Dissolve this ferric 
hydroxide in glacial acetic acid. The solution contains ferric acetate, 
Fe(C2H302)3. 
i6i. Preparation of the Citrate of Iron and Ammonium. Prepare 
ferric hydroxide as above, and quickly and thoroughly wash. Dissolve 
it in as little of a solution of citric acid as possible, thus forming ferric 
citrate. Next add one-third its volume of NH4OH. No ppt. falls, due to 
the formation of a double citrate of iron and ammonium. Evaporated 
over a water bath to a small bulk and spread on glass to dry, it forms 
scales, and is one of the so-called “scale” compounds of iron. 
162. Preparation of Reduced Iron. Prepare a glass tube 18 inches 
long. In one end loosely push some CaCl2, in the other partly fill 4 
inches of the tube with freshly prepared and dried Fe(OH)3. From a 
H generator pass the gas first over the CaCl2 to dry it, and then over 
the Fe(OH)3. Heat the Fe(OH)3 by placing a Bunsen burner under 
the tube, and keep up the evolution of H and heat until no more 
moisture comes from the iron. The iron is left in the tube in a finely 
divided state, and when hot burns spontaneously in the air, forming 
Fe203. 
Reaction—Fe(OH)3 + 3H = Fe + 3H9O. 
163. Preparation of Dialyzed Iron. Dissolve in a warm solution of 
FeCl3 freshly prepared Fe(OH)3. Filter the solution, and place in a 
dialyzer and dialyze through parchment paper until the fresh diffusate 
gives no ppt. with AgN03. Only colloid iron compounds then remain 
in the dialyzer, composed of about 5 per cent of basic ferric-oxy- 
chloride, Fe2OCl4. 
1. What is the difference in Valence in “ous” and “ic” iron? 
2. What is Fe2Cl6? 
3. What is blue vitriol ? White vitriol ? Green vitriol ? 
4. What action has the aircon ferrous compounds? 
5. How much iron in 10 grains of Fel2 ? 
LABORATORY QUESTIONS ON GROUP III. 70 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
6. What members of Group III are pptd. by the group reagent as 
sulphides? Which as hydroxides? 
7. How is carbonate of iron formed? 
8. Why does K3FeCye afford the best distinguishing test for “ous” 
and “ic” iron? 
9. Why do solutions of “ous” iron usually contain “ic” iron? 
10. What compound of iron is found dissolved in chalybeate waters ? 
11. What is the composition of black ink? 
12. What is galvanized iron ? Prepare by dipping bright iron wire 
in melted zinc. 
13. How would one prepare ZnCl3 for “soldering fluid”? 
14. Why would sewer gas turn white paint black ? 
15. In what experiment did you prepare ferrous sulphide ? 
16. If KOH be added to excess to a solution of Fe(ic), A1 and Zn, 
what would occur? 
17. If ammonium salts were added to an alkaline solution of A1 and 
Z, what would occur? 
18. What are the blowpipe tests for Zn and Al? 
19. Could dialyzed iron in the stomach enter the circulation ? 
20. What are the “scale” compounds of iron? 
21. Write the reactions which occur when (NH4)2S is added to solu- 
tions of third group metals. 
22. Make a solution of FeCl3, A12(S04)3, and ZnS04; turn to Ana- 
lytical Table III, page 77, and separate by methods of the third group. 
23. Make a solution of HgN03, K(Sb0)C4H406, A12(S04)3, and 
ZnS04) separate and identify each by Table III, page 77. 
24. Test bottles 13, 14, 15, 16, 17 and 18 on the side table, and re- 
port the metals found in each. 
25. Report the minerals of the first three groups found in ores I, J, 
K and L. 
ANALYTICAL REACTIONS OF GROUP IV. 
164. Barium, Ba//.—Confirm reactions, using solution of BaCl2. 
1. (NH4)2C03 ppts. white BaC03, soluble in acids. 
2. K2Cr04 ppts. 37ellow BaCr04, insoluble in acetic acid, THE METALS. 
71 
soluble in HC1 or HN03. Ca yields no ppt. with this 
reagent. 
3. H2S04 ppts. white BaS04, insoluble in hot water, 
acids or alkalies. 
4. Ammonium oxalate, (NH4)2C204, ppts. wdiite BaC204, 
soluble in HC1 and HN03. 
5. Solids moistened with HC1 and heated in the Bunsen 
flame impart to it a yellowish green tinge. 
165. Calcium, Ca'C—Confirm reactions, using solution of CaCl2- 
1. (NH4)2C03 ppts. white CaC03, becoming crystalline 
on heating. 
2. H2S04 ppts. white CaS04 from strong calcium solu- 
tions, soluble in water and acids. 
3. (NH4)2C204, ammonium oxalate, ppts. white CaC204, 
even in very dilute solutions, soluble in HC1 and HN03, 
insoluble in acetic acid. 
4. Solids moistened with HC1 and heated in the Bun- 
sen flame tinge it dull red, not seen in the presence of 
Ba. 
SOME IMPORTANT SYNTHETICAL REACTIONS OF GROUP IV, 
166. Preparation of Bleaching Powder. Place some damp slaked 
lime in a bottle and pass into the bottle Cl gas. The gas is ab- 
sorbed, forming probably a loosely united compound of calcium hypo- 
chlorite and calcium chloride, thus: 2Ca(OH)2 + 4CI = Ca(C10)2‘ 
CaCl2-fH20. When treated with acids, the Ca(C10)2 breaks up thus: 
2HCI + Ca(C10)2 = CaCl2 + 2HCIO, and in the presence of more acid ; 
2HCIO + 2HC1 = 4H20+ 2CI. When hypochlorites are treated with 
acids they liberate Cl, and chlorides remain in solution. Their so- 
lutions rendered acid bleach litmus solution. 
167. Preparation of Quicklime. Heat a small piece of CaC03 or 
marble in the blowpipe flame, keeping it white hot for some time. 
Cool it, and notice that a portion of it does not effervesce with HC1. 72 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
It dissolves in HoO, and gives the water an alkaline reaction. It is 
CaO, or quickime. 
168. Preparation of Plaster Paris. Heat CaS04'2H20 (gypsum) 
in a test tube until the moisture is all given off. Considerable heat 
is required, but overheating must be avoided. Anhydrous CaS04, or 
exsiccated calcium sulphate, or plaster paris, remains, which when wet 
with a little water quickly hardens. 
Reaction—CaC03 + heat = CaO + C02. 
1. Write the reactions occurring when lime is slaked. 
2. How may calcium chloride be formed? Write the reaction. 
3. Name two important uses you have thus far made of Ba com- 
pounds. 
4. What is gypsum? Is it soluble in water? 
5. Will moist bleaching powder give off Cl ? 
6. What is the composition of slaked lime? 
7. What is anhydrous gypsum called? 
8. Make a solution of gum arabic (calcium gummate), and test for 
calcium by test 165-3. 
9. What is whiting? Whitewash? Why does mortar harden when 
exposed to the air? 
xo. Will lime harden under water or protected from the air ? Why ? 
11. How were the marbles and limestones formed? 
12. How are stalactites and stalagmites formed? 
13. What test best distinguishes Ba from Ca? 
14. Make a solution of BaCl2 and CaCl2, and turn to Table III, page 
77, and separate according to the scheme for Group IV. 
15. Make a solution of CuS04, As203) FeCl3, BaCl2, and CaCl2, and 
separate and identify each metal by the table. 
16. Test bottles 19, 20, 21 and 22 on the side table for metals of 
the first four groups, reporting the metals found in each. 
LABORATORY QUESTIONS ON GROUP IV. 
ANALYTICAL REACTIONS OF GROUP V. 
169. Magnesium, Mgr/.—Confir?n reactions, using solution of 
MgCl2- 
1. (NH4)OH and (NH4)2C03 give no ppts. in presence 
of ammonium salts. THE METALS. 
73 
2. (NH4)2HAs04 ppts. white NH4MgAs04 in presence 
of (NH4)C1 and (NH4)OH. 
3. Na2HP04 ppts. white crystalline Mg(NH4)P04 in 
presence of NH4C1 and (NH4)OH, hastened by stirring. 
4. Solids fused on charcoal, moistened with CoCl2 and 
reheated yield a pink mass. Metallic Mg burns with a 
brilliant white light, leaving MgO. 
170. Potassium, K'.— Confirm reactions, using a solution of 
KCl. 
1. PtCl4 ppts. yellow crystalline double chloride PtCl4- 
2KCI from moderately concentrated solutions, hastened by 
presence of alcohol. 
Test thus: To 1 drop of a solution of KCl, on a micro- 
scope slide, add 1 drop of PtCl4 and 1 drop of alcohol; stir, 
set aside, and examine with the microscope for yellow octa- 
hedral crystals. 
2. H2(C4H406), tartaric acid, ppts. white crystalline KH- 
(C4H406), promoted by stirring. 
3. Solids heated on platinum wire in the non-luminous 
Bunsen flame tinge it violet, seen through blue glass. 
171. Sodium, Na/.— Confirm reactions, using a solution oj 
NaCl. 
1. Neither PtCl4 or H2(C4H406) yield ppts. 
2. Solids heated on platinum wire in the non-luminous 
Bunsen flame tinge it intensely yellow, not seen through 
thick blue glass. 
172. Ammonium, NH/.—Confirm reactions, using solution of 
NHxCl. 
1. PtCl4 and H2(C4H406) ppt. as with K. 
2. Heated with KOH or NaOH, fumes of NH3 are 
evolved. 74 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
3. Nessler’s reagent1 ppts. brown NHg2I, or in dilute 
solutions a yellow coloration. 
4. Solids heated on platinum foil volatilize completely. 
K or Na salts do not. 
SOME IMPORTANT SYNTHETICAL REACTIONS OF GROUP V. 
173. Preparation of Potassium Hydroxide. Boil in a test tube with 
water equal parts of K2C03 and Ca(OH)2, set aside, and when subsided 
decant the KOH solution. 
174. Preparation of Potassium Iodide. Into 10 c.c. of a warm solution 
of KOH stir crystals of I until the solution is permanently faint yellow. 
Evaporate to dryness. 
Reaction—6K0H+3l2=5KI+KI03+3H20. 
Heat the resulting product containing potassium iodide and iodate 
with an equal part of finely powdered charcoal until a slight incandescence 
ensues. 2KI03-)-3C2=2KI+6C0. Treat the mass when cool with water, 
warm, filter, evaporate and crystallize out the KI. 
175. Preparation of Potassium Permanganate. Mix equal parts of 
solid KOH, KCIO3 and Mn02. Fuse the mixture on platinum foil until 
it is dark green. 
Boil this mass in water, and a purple solution of potassium perman- 
ganate results. 3KoMn04+2H20=K2Mn208+Mn02+4KOH. 
Reaction—6K0H+3Mn02+KC10=3K2Mn04+KCl+3H20. 
176. Preparation of Cream of Tartar. To ioc.c. of a strong cold solu- 
tion of KNO3 add an excess of a strong solution of tartaric acid. A 
white ppt. falls of acid potassium tartrate, KH(C4H406), or cream of 
tartar. This method merely illustrates a possible method of preparation. 
It is not the method of commerce. 
177. Preparation of Sodium Bi-Carbonate. Prepare a concentrated 
solution of Na2C03 in less than its own weight of water. Cool this, and 
slowly let C02 bubble through the solution for some time. Set aside and 
Note i. To a solution of HgCl2 add KI until the ppt. is nearly all redissolved. 
Render strongly alkaline with KOH. Set aside. Decant the clear straw-yellow solu- 
tion for use. THE METALS. 
75 
decant, drying the precipitated NaHC03 on filter paper. Note that an 
equal quantity of this acid sodium carbonate is alkaline in reaction, and 
effervesces more violently with acids than the original Na2C03. 
Reaction—Na2C03+C02+H20=2NaHC03. 
178. Preparation of Rochelle Salts. To a strong hot solution of 
Na2C03 add cream of tartar (KH)(C4H406) until no further effervescence 
occurs. Set the solution aside to cool, and the double salt, potassium 
and sodium tartrate, KNa(C4H406) will crystallize out. 
179. Preparation of Sodium Hypochlorite. Make a clear solution of 
bleaching powder. Dissolve in a little hot water twice as much Na2C03 
as the weight of bleaching powder used. Mix the two solutions and 
filter. Add water to the filtrate until the hydrometer, immersed in it, 
stands at 1.059. The solution (Labarraque’s Solution) contains sodium 
hypochlorite, NaCIO, a useful disinfectant, liberating Cl. 
Reaction—Na2C03+2KH(C4H406)=2KNa(C4H40fl)+C02+H20. 
Reaction—Ca(C10)2+2Na2C03=2NaC10+CaC03. 
180. Preparation of Ammonium Sulphide, Pass H2S through a solu- 
tion of NH4OH until the solution no longer gives a ppt. when a few 
drops are added to a little magnesium sulphate solution. Ammonium 
hydrosulphide is formed, NH4HS. (Reaction NH4(OH)tH2S= 
NH4HS+H20). To this solution add nearly an equal volume of 
NH4OH. Ammonium sulphide, much used in analysis, is formed thus : 
NH4HS-f-(NH4)OH=(NH4)2S-rHoO. Yellow ammonium sulphide is 
usually more efficient, and is prepared by adding to ammonium sulphide 
a pinch of flowers of sulphur, or letting the reagent stand for some time 
until yellow. (NH4)2S2 is thus formed. 
LABORATORY QUESTIONS ON GROUP V. 
1. What peculiar action has ammonium salts on solutions of Mg? 
2. How may both K and NH4 be detected in a mixture? 
3. What is the original source of K2CO3, used in 173? 
4. What is cream of tartar ? Write its reaction on bicarbonate of soda. 
5. How might you manufacture baking powder? 
6. Why does soda sweeten sour batter cakes? 
7. Why is NaHC03 called bicarbonate of soda ? 76 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
8. What are Rochelle salts? Epsom salts? Glauber’s salts? 
9. In what operations has yellow (NH4)2S or (NH4)2S2 been used? 
10. How might ammonium acetate be prepared? 
11. For what purpose is NaHCC>3 more useful than Na2CC>3? 
12. What is pearlash ? Sal soda? Saleratus? Soda? 
13. What is calcined magnesia (169-4)? Is it soluble in water? Is the 
attempted solution alkaline? Write the reaction. 
14. Make a solution of K, Na and NH4 salts, and separate by Table 
III, page 77, under Group V. Note i. In actual analysis, before operating on the whole quantity, the different group precipitants are added to a few drops of the solution. In case any group 
reagent fails to give a ppt., none of that group is present, and that reagent need not be added to the whole amount when analyzed. 
Note 2. Often when no second group metals are present, S falls here in the form of a yellowish white ppt., due to the action of acids in the solution or the reduction 
of “ ic ” to “ ous ” compounds, like iron, belonging to the third group. 
Note 3. If phosphoric, boric or oxalic acids were present in the solution Ba, Ca and Mg will be pptd. here, since their phosphates, etc., are not soluble in alkaline 
solutioiKli^hi^as^ 
Precipitate Group I. 
Pb Ag Hg(ous). 
Wash,boil with water, filter. 
Cu Pb Hg(ic) 
Second Group Precipitant. 2 Pass H 2 
Filtrate 
Bi As Sb—Fe A1 Zn—Ba Ca—Mg K Na NH4. 
S through the liquid until it causes no further precipitation; warm and filter. 
Precipitate 
Ag Hg(ous). 
Pour NH4OH 
over the well 
washed ppt. on 
the filter. 
Filtrate 
Pb. 
Add 
H2SO4 
and set 
aside. 
White 
ppt. = 
lead. 
136-5- 
Precipitate Group II. 
Cu Pb Hg(ic) Bi-As Sb. 
Wash, digest in yellow (NH4) 2S, filter. 
Filtrate Fe A1 Zn-Ba Ca-Mg K Na NH4. 
Third Group Precipitants. Add NH4OH until alkaline, 
then (NH4) 2S and (NH4)C1, agitate, filter. 
Precipitate 5 
Cu Pb Hg(ic) 
Bi. 
Filtrate 
As Sb. 
Acidulate with H(C2 
H3O2). Boil and 
filter. Ppt. = As Sb. 
Boil with strong HC1, 
Precipitate* Group III. 
Fe A1 Zn. 
Filtrate Ba Ca—Mg K Na NH4. 
Fourth Group Precipitant. Add 
Residue 
Hg(ous). 
Black. 
I37-I- 
Filtrate 
Ag. 
Render 
acid by 
HNO3. 
White 
ppt. = 
Ag 
135-1- 
Wash, dissolve in 
aqua 
* • 
1 . *i , 11 
01 1' 
regia, evaporate to small 
bulk, cool, filter, divide 
into 4 parts. 
bulk; add KOH to excess; 
agitate, filter. 
Precipitate 
Group IV. 
Ba Ca. 
Wash; dissolve 
in H(C2H302); 
boil and add 
K2Cr04; 
filter. 
Filtrate Group V. 
Mg K Na NH4. 
Add (NH4)2HAs04; 
stir, filter. 
Precipitate 
Fe 
Test the 
original 
solution by 
K3FeCy6 
for *‘ic” 
and -‘ous” 
iron. 
154-4- 
Filtrate 
A1 Zn 
Acidulate with 
HC1; make 
alkaline with 
NH4OH; stir, 
filter. 
Cu 
> 
CL 
CL 
Pb 
> 
CL 
CL 
Hg(ic) 
> 
CL 
CL 
Bi 
0 
3 
Residue 
As. 
Yellow. 
Confirm by 
dissolving 
in hot HC1 
KCIO3. 
Boil off Cl 
and test 
solution by 
Marsh’s 
Test. 
Hi-4. 
Filtrate 
Sb. 
H2S gives 
orange 
ppt. or 
solution 
may be 
tested by 
Marsh’s 
Test. 
142-5. 
3 
X 
n 
3 
5* 
<■+■ 
Precip. 
Ba. 
Yellow 
Con- 
firm by 
164-5. 
Filtrate 
Ca 
Add 
(NH4)2 
c2o4. 
White 
ppt. 
165-3- 
Ppt. 
Filtrate 
K Na NH4. 
Evaporate: ig- 
nite; dissolve 
in H20; divide 
in two parts. 
0 
X 
o’ 
•CG 
n> 
m rt> 
KJ 2 
3 
n> 
c/> 
0^ 
If) 
O 
_ in 
n> 
Gj 
Y 
-U. 
O 
3 
3 
0 
3* 
„ X 
Gj to 
’ 3 
2t 
0) 
Precip. 
Al. 
White 
ppt. 
Con- 
firm by 
155-4- 
Filtrate 
Zn. 
Add 
(NH4)2 
S. 
White 
ppt.Zn. 
Con- 
firm by 
156-6. 
3 
3* 
n> 
p 
i_i in 
Cm 
' % 
CT 
00 -r* 
1 S- 
• <T> 
P 
3 
CL 
P 
g- 
g 
X 
ON 
VO 
1 
K) 
K 
Test by 
Pt.Cl4. 
Yellow 
ppt. 
170-1. 
Na 
Flame 
test 
Yellow 
170-2. 
3 
0’ 
3 
II 
•o 
II 
in 
3 
O 
W 
nh4 
Test original sol. 
by heat with 
KOH. 172-2. 
An Analytical Table for Separating and Identifying the More Important Medicinal Metals in Aqueous Solution. 
First Group Precipitant. 1 Add HC1, drop by drop, as long as a ppt. forms; filter. 
TABLE III. EXERCISES 
IN 
GRAVIMETRIC AND VOLUMETRIC 
PROCESSES 
APPLIED TO 
SANITARY WATER ANALYSIS EXERCISES IN GRAVIMETRIC PROCESSES. 
81 
EXERCISES IN GRAVIMETRIC PROCESSES. 
181. Determination of the Per Cent of Soluble Solids. Weigh 
a clean, dry evaporating dish on a good balance.1 Fill the 
dish three-fourths full of the liquid under examination, as, 
for example, drinking water. Carefully reweigh. Evapo- 
rate the solution to dryness over a slow fire, or better, a 
water bath, avoiding loss by “spitting.” Cool the residue 
by placing the dish under a desiccator.2 Remove the resi- 
due, when cold, to the balance and quickly weigh. From 
these data compute the per cent of solids. 
182. Determination of the Approximate Weight of a Precipitate. 
Determine the amount of lead in a solution thus : Precipi- 
tate the solution by passing H2S through it for some time. 
Weigh a well-dried filter paper. Filter the solution through 
this paper, collecting the well-washed precipitate on it. 
Dry the funnel and its contents in a drying oven. Cool the 
dry paper and its dry precipitate in a desiccator. Weigh, 
and subtract the weight of the paper. The remainder is 
the weight of lead sulphide, PbS. From this compute the 
actual amount of lead in the solution. 
183. Determination of the Exact Weight of a Precipitate. To 
determine the per cent of S04 in sodium sulphate, weigh 
accurately a small porcelain crucible. Place in it a large 
pinch of dry, powdered sodium sulphate. Reweigh the 
Note i. A good balance must be carefully handled. Special instruction in the 
methods of weighing, handling weights, determining centers, care of the balances, 
etc., will be given by the demonstrator. 
Note 2. This is a bell-jar containing a dish of strong H2SO4, which absorbs all 
the moisture, and keeps the material from gaining in weight. 82 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
crucible and contents. Carefully wash the salt into a 
beaker with about 25 c.c. of distilled water. Add a few 
drops of HC1, and heat to boiling. Next add BaCl2 until 
no further ppt. is formed, boil and filter through a fine 
Swedish filter paper, which has a known ash. Wash the 
ppt. with distilled water until the washings no longer ren- 
der AgNOg solution turbid, showing absence of chlorides. 
Dry the filter in an air bath. Fold up the dry paper com- 
pactly. Wrap a platinum wire about it. Hold it over the 
crucible. Burn it and shake the ash into the crucible. 
Heat the crucible to redness for a few minutes, until all 
carbon is burned and the residue is white. Cool in a desic- 
cator. Weigh when cold. Subtract from this weight the 
weight of the crucible and the known filter ash. The re- 
mainder is the weight of barium sulphate. Knowing the 
weight of Na2S04 taken and BaS04 found, 
(1) From the weight calculate what % of 
the BaS04 is S04 
(2) From the weight calculate what % of 
Na2S04 was S04 ... 
Error ========_ 
EXERCISES IN VOLUMETRIC PROCESSES. 
Volumetric solutions are solutions of a definite weight 
of a given substance dissolved in a definite amount of dis- 
tilled water. They are designated by the U. S. P. “as 
normal («) when they contain in one litre the molecular EXERCISES IN VOLUMETRIC PROCESSES. 
83 
weight of the active reagent expressed in grams and 
reduced to the valency corresponding to one atom of 
replaceable hydrogen.” A decinormal solution (Tnff) is 
xV the strength of a normal one, and is preferable in many 
operations. 
ACIDIMETRY. 
184. The Process of Determining the Amount of Free Acid in 
a Solution. 
The Solution. A decinormal volumetric solution of KOH 
is prepared by dissolving 5.599 grams of solid KOH in 
distilled water, and making up the solution to 1,000 c.c. at 
150 C. In accurate work this must always be standardized. 
The Process. The process is known as titration. A 
burette is filled with decinormal KOH solution up to the 
0° mark. Place in a beaker a known quantity of the clear 
solution in which the free acid is to be estimated. (Use 
30 c.c. of acidum hydrochloricum dilutum, and calculate 
the per cent of acid.) Add to the beaker 5 drops of a 
solution of phenolphthalein as an indicator, which turns 
red with the slightest excess of alkali. Place the beaker 
on white paper, and with constant stirring add the alkali 
from the burette, drop by drop, until a faint pink tinge 
becomes permanent. Read off the number of c. c.’s of alkali 
required to neutralize the acid. From the following table 
the exact weight of the acid may be computed. Each c.c. 
of alkali neutralizes exactly— 
Acetic Acid, absolute H(C2H309) 
0.005986 g. 
Citric Acid, H3(C6H507)H90 
Hydrobromic Acid, absolute HBr 
Hydrochloric Acid, absolute HC1 
0.003637 84 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
Hydriodic Acid, absolute HI. 
Hypophosphorous Acid, H(H0P02) 
. .. 0.006588 
Lactic Acid, absolute H(C3H503) . ...... 
Nitric Acid, absolute HN03 
. .. 0.006289 
Oxalic Acid, crystallized H9C204-H20 .. . 
. .. 0.006285 
Phosphoric Acid, absolute H3P04 
Sulphuric Acid, absolute H<>S04 
. . . 0.004891 
Tartaric Acid, crystallized H9(C4H406) .. . 
ALKALIMETRY. 
185. The Process of Determining the Amount of Free Alkali in 
a Solution. 
The Solution. A decinormal volumetric solution of oxalic 
acid, H2C204-2H20, is prepared by dissolving 6.285 grams of 
pure crystals in distilled water, and making up to 1,000 c. c. 
at 150 C. In accurate work this solution must always be 
standardized. 
The Process. Fill a burette with decinormal oxalic acid 
solution up to the 0° mark. Place in a beaker a known 
amount of any clear solution in which the amount of free 
alkali is to be determined. (Use 100 c.c. of liquor calcis, 
and prove that it contains 14% of Ca(OH2), as required.) 
Color the solution yellow by a few drops of methyl-orange 
solution for an indicator, which turns red with the slightest 
excess of acid. With constant stirring, drop in the oxalic 
acid from the burette until the pink color appears. Read 
off the number of c.c.’s of acid used, and compute the 
absolute weight of alkali. Each c. c. of oxalic acid neutral- 
izes exactly— 
Ammonia Gas, NH3 
Ammonium Carbonate, (NH4')0CO-! 
0.004793 85 
EXERCISES IN VOLUMETRIC PROCESSES. 
Calcium Hydroxide, Ca(OH), 
Potassium Hydroxide, KOH 
0.005599 
Sodium Bicarbonate, NaHC03 
0.008385 
Sodium Carbonate, Na9C03 
0.005292 
Sodium Hydroxide, NaOH 
186. Estimation of Chlorine. 
The Solution. A standard volumetric solution of silver 
nitrate convenient in water analysis is prepared by dissolv- 
ing 4.79 grams of pure AgN03 in distilled water and making 
it up to 1,000 c.c. at i5°C. This solution is of such 
strength that i c.c. of it precipitates exactly one milli- 
gram of chlorine (or i c.c. is equivalent to .00165 g. of 
NaCl). The solution must be kept in a dark container. 
The Process. Fill a clean burette to the 0° mark with the 
standard solution of silver nitrate. Place a beaker on a piece 
of white paper. In it put a known quantity of the clear 
solution in which chlorides are to be determined. (Take 
70 c.c. of drinking water.1) Add a crystal of K2Cr04 to color 
the water lemon-yellow. With constant stirring, drop in the 
silver nitrate from the burette until a faint red color is per- 
manent. Read the number of c. c.’s used. Refill the burette 
and repeat the process with an equal volume of distilled 
water exactly matching the red color. Read the number of 
c.c.’s used, and deduct this from the first reading, as the 
amount required to produce the color. The number of c.c.’s 
remaining represents grains of chlorine per gallon, or may be 
calculated as sodium chloride. 
Note i. Seventy c.c. of distilled water weighs 70,000 milligrams. The imperial 
gallon contains 70,000 grams, hence the number of milligrams of solids in 70 c.c. will 
likewise express the number of grains in a gallon. 86 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
SANITARY 
ANALYSIS OF POTABLE WATERS. 
187. Detection of Poisonous Minerals. Poisonous metals 
most commonly present in potable waters are lead and 
copper, sometimes arsenic, zinc, etc. A quantity of water is 
evaporated to a small bulk. The metals may be then identi- 
fied by the general methods of qualitative analysis given in 
Table III, page 77. 
188. Determination of Total Solids. Find the total solids in 
70 c.c. of water, according to the method in 181. The num- 
ber of milligrams of solids likewise expresses grains per 
imperial gallon. River waters usually contain less solids 
than well waters. Solids ought not to run over 30 or 40 
grains per gallon (Wanklyn). Artesian water often runs 
higher. The presence of carbonates in the residue is evinced 
by effervescence when touched with acid. 
189. Determination of Chlorine. Find the number of grains 
of chlorine per gallon, as in 186. Pure waters, unless 
charged from some uncommon mineral deposits, contain 
little chlorine. Urine and sewage contaminated from animal 
excretions are highly charged with chlorides. A water free 
from chlorides could not have been contaminated. Water 
containing much chlorine would be looked upon with sus- 
picion until its albuminoid ammonia had been determined. 
River water contains not far from 1% of chlorides. Well 
water contains more. Five or six grains of chlorine per 
gallon does not injure water, but is a reason for suspicion. SANITARY ANALYSIS OF POTABLE WATERS. 
87 
190. Determination of Free and Albuminoid Ammonia. 
I. Distillation. Thoroughly cleanse a Liebig condenser 
and a glass retort holding 1 litre. Arrange them for distil- 
lation. In the retort place 500 c.c. of the water under 
examination. Add a handful of broken, well-washed glass, 
to keep from “bumping.” Slowly distill, catching each 
50 c.c. of distillate in a large tube, and set each aside in 
the order of distillation until four tubes are filled, representing 
200 c.c. These contain any free ammonia in the original 
portion, and are to be examined later by (a). 
Stop the distillation. Add 50 c.c. of permanganate solu- 
tion1 through a funnel, and begin to distill very cautiously 
to avoid bumping. Catch each 50 c.c. of distillate in a large 
tube, and set each aside as before until three are obtained. 
These contain ammonia from any organic matter present in 
the original solution, and are to be examined later for albu- 
minoid ammonia by (b). 
II. Nesslerizing. Prepare two solutions of ammonium 
chloride. 
1. 3.15 g. of NH4C1 dissolved in 1 litre of distilled water. 
1 c.c. contains 1 milligram of ammonia. 
2. Dilute 1 c.c. of the above with 99 c.c. of water. 1 c.c. 
contains of 1 milligram of ammonia. 
(.a) Estimation of Free Ammonia. Take the tubes con- 
taining the free ammonia distillate. Into the first drop 
2 c.c. of Nessler’s reagent (172-3, Note 1), and stir. It will 
strike a yellow or brownish color if traces of ammonia are 
present, assuming its deepest permanent hue in 3-5 minutes. 
The next process consists in making an artificial solution, 
Note i. The permanganate solution is prepared by dissolving 200 grams of solid 
potassium hydroxide and 8 grams of crystallized potassium permanganate in water, 
boiling for 20 minutes and making up to 1,000 c.c. with distilled water. This solution 
oxidizes organic matter and, in the presence of an alkali, liberates N in the form of NH3. 88 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
with a known amount of ammonia, that strikes the same 
color with Nessler’s reagent. Take a tube containing about 
45 c.c. of water free from ammonia. Add for the first trial, 
say 3 c.c. of the dilute ammonium chloride solution. Stir. 
Add 2 c.c. of Nessler’s reagent. Stir, and compare the two 
colors by looking down through the solutions on a white 
surface. If the colors do not exactly agree in depth of 
shade, make another solution with more or less ammonium 
chloride, which will exactly match the distillate. The 
amount of ammonia added, obviously, is the amount con- 
tained in the first 50 c.c. of distillate. 
The remaining tubes might be Nesslerized, but as the 
first tube invariably contains three-fourths of the entire free 
ammonia, it is easier to add one-third for the total amount of 
free ammonia contained in the 500 c.c. of water examined. 
(3) Estimation of Albuminoid Ammonia. Nesslerize, in 
the manner described, each tube containing albuminoid 
ammonia, and add the results for total albuminoid ammonia 
in the 500 c.c. of water taken. 
(y) Discussion of Results. 
EXAMPLE OF ANALYSIS. 
IN 500 C.C. 
Free ammonia 
milligram. 
H 
Correction, 
Total 
« 
Albuminoid ammonia 
milligram. 
< i 
<< << 
(( (( 
< < 
Total 
<< 
IN ONE LITRE. 
Free ammonia 
Albuminoid ammonia 
( < SANITARY ANALYSIS OF POTABLE WATERS. 
89 
If water contains 0.00 parts of albuminoid ammonia per 
million (that is, milligrams per litre), it is organically pure. 
If it contains 0.02-0.05 it is classed with good waters. 0.10 
begins to be a suspicious sign, and 0.15 ought to condemn the 
water (Wanklyn). In river waters, where the organic matter 
is from vegetable origin, even a somewhat higher amount of 
albuminoid ammonia might exist, however, without serious 
effects. 
191. Determination of Other Ingredients. Many other deter- 
minations are sometimes made in sanitary analysis of water, 
which may serve for valuable deductions concerning water 
supply, etc., such as the determination of nitrites, nitrates, 
hardness, bases, acids, oxygen-consuming power, etc. The 
above, however, are all that are usually required in determin- 
ing the purity of water. The residue from concentration 
may be used in determining the bases and acids present by 
the ordinary processes of analysis. See Tables I, II and III. 
For further work, the student is directed to Wanklyn’s 
Water Analysis. LABORATORY EXERCISES 
IN THE 
MEDICINAL 
ORGANIC COMPOUNDS. ORGANIC CHEMISTRY. 
93 
ORGANIC CHEMISTRY. 
192. Determination of the Fusing Point. Select a fine capil- 
lary tube, of an internal diameter just sufficient to insert 
a fine wire. Seal one end. Push a very small amount 
of the substance under examination into the lower end 
of the tube. Fasten the tube to a good chemical ther- 
mometer by a rubber band, and insert the whole in a beaker 
of water. Apply a gentle heat to the beaker, and as the 
temperature rises carefully note the reading of the ther- 
mometer the moment the solid melts. Whenever the fusing 
point is above ioo° C., a beaker of melted paraffin may be 
used. Any impurity will account for variations in the fusing 
points. Determine the fusing points of the following sub- 
stances : 
Substance. 
Observed. 
Given. 
Chloral hydrate 
57° C. 
Naphthalene 
79° C. 
Stearic acid 
69° C. 
193* Determination of the Boiling Point. Place about io c.c.’s 
of the liquid under examination in a dry, clean 7-inch test 
tube, fitted with a 2-hole rubber stopper, holding a ther- 
mometer, which should nearly touch the surface of the liquid, 
and be free from the sides of the tube. Place a few bits of 
broken glass in the liquid to assist in the boiling. Place the 
whole in a beaker of water or melted paraffin, as required. 
Apply a gentle heat, and carefully note the reading of the 94 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
thermometer when the liquid is boiling vigorously and the 
thermometer stem is thoroughly surrounded by vapor. 
Determine the boiling point of the following substances. 
When the determination is made, return the liquid to its con- 
tainer. 
Substance. 
Observed. 
Given. 
Ethyl Alcohol 
78° C. 
Methyl Alcohol 
66° C. 
Ether 
35° C. 
194. Optical Activity of Organic Chemicals. Examine with 
the polariscope the prepared solutions of cane sugar, which 
is dextro-rotary, and morphine hydrosulphate, which is laevo- 
rotary. 
195. Detection of Carbon and Hydrogen in Organic Compounds. 
Dry and powder the substance under examination, as, for 
example, tartaric acid. Mix it with twice its bulk of dry? 
finely pulverized cupric oxide, CuO. Place the mixture in a 
test tube, fitted with a delivery tube, constructed so that any 
gas formed may pass through a glass tube, in which is loosely 
placed a few pieces of dry CaCl2, and then bubble through 
clear lime water. Heat the test tube to a dull red. The 
moistening of the CaCl2 indicates H20, and a precipitate in 
the lime water, C02, both formed from the union of the H 
and C of the tartaric acid with the O of the CuO. Note that 
metallic copper remains in the test tube. 
iq6. Detection of Nitrogen in Organic Compounds. Place in a 
dry test tube a small piece of metallic sodium. Cover this 
with the dry powdered solid under examination, as, for 
example, urea or any alkaloid, and heat. Cyanides are ORGANIC CHEMISTRY. 
95 
formed if the compound contains nitrogen. Test the resi- 
due for cyanides by adding water, filtering and boiling with a 
drop each of FeS04 and NaOH, then adding a drop of FeCl3 
and acidulating with HC1. Cyanides yield a ppt. of Prussian 
blue, which is best seen on the filter paper when the solution 
is filtered (129). 
197. Detection of Sulphur in Organic Compounds. 
(1) Take some lead acetate solution in a test tube. Add 
KOH until the precipitate first formed dissolves. In this 
drop a little finely powdered organic substance containing 
sulphur, like albumin. Boil, and notice the blackening of 
the sulphur compound. A still more delicate test is the 
following : 
(2) In a dry test tube place a small piece of metallic 
sodium. Cover this with the dry powdered substance under 
examination, like albumin, and heat. If the compound con- 
tains sulphur, sodium sulphide, Na2S, will be formed. After 
prolonged ignition, dissolve this residue in water. Filter, 
and add a few drops of sodium nitro-prusside, which yields 
with sulphides a purple coloration. 
198. The Determination of Formulae. Examine the combus- 
tion furnace with the combustion tube, containing an intimate 
mixture of CuO and .46 g. of acetic acid. Note the arrange- 
ment of the weighed CaCl2 tubes to retain the H20. Evi- 
dently their increase in weight will be the weight of H in 
the compound. Note the weighed potash bulbs arranged to 
absorb all C02. Evidently of their gain in weight will 
represent the C in the acetic acid. The remaining weight of 
the substance we know to be O, and its amount can be 
determined by the method of difference. 96 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
Result of the Combustion of .46 g. of Acetic Acid. 
C02— .6765 g.XfV 
—1845 g- of C, 
or 40.11% 
H20=.2817 g.x i 
=.°3i3g. of H, 
or 6.82% 
0 by difference 53.07% 
100.00 
This does not give us the formula. The weight of one 
molecule is determined by the Victor Meyer vapor density ap- 
paratus. Examine this instrument, with its outer casing in 
which aniline has been boiled, and the inner tube surrounded 
by hot aniline vapor. Note the little bottle in the inner tube, 
which was dropped in when the apparatus was hot. It con- 
tained .09 g. of acetic acid, which vaporized and crowded out 
33.48 c.c. of air into the graduated tube. 33.48 c.c. of acetic 
acid vapour, then, weighs .09 gram. 33.48 c.c. of H weighs 
.00299 gram (1 c.c. = .0000896 g.). Hence the acetic acid va- 
pour is about thirty times as heavy as an equal volume of H 
(.o'o°2'9~9 = 3°)- Avogadro’s law states that equal volumes of 
gases under equal conditions contain equal numbers of mole- 
cules. Then a molecule of acetic acid weighs thirty times 
as much as a molecule of hydrogen (H2), and 60 times an 
atom of hydrogen (H). The molecular weight of acetic acid, 
then, is 60, and the formula is thus calculated : 
Computation of Formula, Given Percentage Composition and Molecular 
Weight. 
c 
= 40.11% X 60 — 
24.06 -7- 
12 
= 2 
H 
= 6.82% X 60 = 
4.09 -~- 
1 
= 4 
O 
= 53-°7% x 60 = 
31.84 -7- 
16 
= 2 
Thus the formula of acetic acid is C2H402 = 6o. ORGANIC CHEMISTRY. 
97 
1. Of what value is the estimation of the boiling and fusing points ? 
2. In the determination of boiling points, why should the thermometer 
not touch the liquid ? 
3. What are the causes of inaccuracy in determinations of boiling and 
fusing points ? 
4. Of what value is a knowledge of the optical activity of substances ? 
5. Why is the detection of N often valuable ? 
6. Deduce the formula for alcohol with a molecular weight of 46, 
when C = 52.18% ; H = 13.04% ; O = 34.78%. 
7. Sulphuric acid has a molecular weight of 98. Deduce the formula 
when H = 2.04% ; S = 36.65% ; O =65.31%. 
8. Chloroform has a composition C= 10.04%; H = .84%; Cl = 
89.12%. What are some possible formulas? How would its formula be 
decided ? 
9. What are some of the difficulties which keep compounds from 
having their formulas accurately determined? 
LABORATORY QUESTIONS. 
199. Determination of the Flashing Point of Kerosene. Fill a 
7-inch test tube one-third full of kerosene. Insert a ther- 
mometer, also a bent glass tube so arranged that air can be 
blown through the oil and bubbles of foam kept constantly 
upon its surface. Place the test tube in a beaker of water. 
Apply a gentle heat, so that the temperature rises i° in two 
or three minutes. At each rise of i°, blow for a few seconds 
through the glass tube until foam stands on the oil, then 
apply a flame to the mouth of the tube. When the flame 
flashes down to the oil, the reading of the thermometer gives 
the flashing point. A second determination, with a fresh 
sample, will enable a more accurate result to be secured. The 
laws should require oil to have a flashing point above the 
maximum temperature of the atmosphere in the locality 
where it is used. 
200. Preparation of Iodoform. In half a test tube of water 
put 2 c.c. of alcohol and 3 c.c. of KOH. Warm and add 98 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
crystals of metallic iodine, with constant stirring, until a fine 
yellow powder becomes visible. Filter the solution, and 
examine the crystals of iodoform, CHI3, on the filter paper. 
Reaction— 
(C2H5)OH + 4I2+6KOH = CHI3+ K(CH02) + 5KI + 5H0O. 
Alcohol Iodoform Pot. Formate 
201-a. Preparation of Chloroform. In a generator put about 
3 grams of chloral hydrate, cover with KOH solution, and 
warm and condense the vapor in a test tube immersed in a 
beaker of ice water. Some water will be condensed with 
a globule of pure chloroform, CHC13, which will have the 
chloroform odor, and, when poured on the hand, will 
quickly evaporate. The purest chloroform is prepared by 
this method. It may also be prepared by the action of 
alcohol and bleaching powder. 
Reaction—CClg-COH + KOH = CHC13 + K(CH02) + H20. 
Chloral Chloroform Pot. Formate 
201-b. Tests for Chloroform. 
1. The Iso-7iitrile Test. In a test tube take a little alcohol 
and KOH. Add a drop of chloroform and a drop of aniline. 
Warm, and the peculiar disagreeable, persistent odor of 
benzyl-iso-cyanide is developed. 
Reaction— 
CHC13 + 3KOH + C6H5NH2 = C6H5Cy + 3KCI + 3H20. 
2. The Flame Test. Prepare and light a H generator. 
A rod, wet with ammonia, above the flame gives no fumes, 
and a copper wire in the flame does not color it, except 
momentarily. Through the thistle tube add a drop of 
chloroform. The Cl escapes as HC1, and yields fumes of 
ammonium chloride, with the rod wet with ammonia, and 
the wire heated colors the flame green from the constant 
formation of CuCl2. ORGANIC CHEMISTRY. 
99 
202. Preparation of Alcohol by Fermentation. Alcohol may 
be prepared from the fermentation of molasses or sugar, 
but the following process illustrates the usual commercial 
method. In a saucepan, or large evaporating dish, boil a 
quart of water. Into this slowly sift a mixture of flour and 
cornmeal, with constant stirring, until a thin, even mush is 
produced. Cool this to 6o° C, and put into a large flask or 
bottle. Next pound up some dry malt (see 254). Add water 
and filter out the husks. Add the solution to the mush. Stir, 
and notice how rapidly the mush liquefies as the diastase of 
the malt converts starch to malt sugar. Next add some 
yeast to the solution. Close the bottle with a perforated 
cork, in which a delivery tube is so fitted that it dips into a 
beaker of lime water. Notice that C02 is soon evolved, as 
indicated by the turbidity of the lime water. When the 
action nearly ceases, after about two days, examine a few 
drops of the solution under the microscope, and note the 
form of the yeast plant (,Saccharomyces cerevisice). Next 
filter the solution into the distillation flask, and distil in the 
apparatus prepared by the demonstrator. Note the tem- 
perature at which distillation begins, and continue until the 
thermometer rises to about 96°. Test this distillate by the 
iodoform test, 204. 
This distillate can be shaken with quick lime, which 
removes water, unites with any acetic acid formed, and 
decomposes any etherial salts. It can then be filtered and 
redistilled. The strongest alcohol obtained by mere distil- 
lation is called “rectified spirits,” and contains about 7% of 
water. 
203. Absolute Alcohol. Heat a few grams of copper sul- 
phate (CuS04-5H20) until it loses its water of crystalliza- 
tion, and is white. Shake the powder with alcohol. After 100 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
standing, if water is present, the blue color is restored to 
the salt. This test for water in alcohol affords a convenient 
method of preparing nearly absolute alcohol, but it contains 
some CuS04 in solution, which, however, does not interfere 
with its use in preserving and hardening specimens, etc. 
It may be purified by distillation. Commercially, absolute 
alcohol is prepared by distilling alcohol from quicklime, 
adding a little metallic sodium and redistilling. 
204. The Iodoform Test for Alcohol. Warm a portion of 
the suspected alcohol with KOH. Add crystals of I, and 
stir as long as the iodine is decolorized, or until a yellow 
powder appears. Cool and set aside. If alcohol were 
present, yellow crystals of iodoform, CHI3, precipitate, and 
can be seen by the microscope as hexagonal stars and ro- 
settes. Some other organic compounds, like acetone, alde- 
hyde, etc., yield the iodoform test, but do not cause confu- 
sion in testing potable liquids. 
205. Detection of Alcohol in Beer, Etc. Distill a small quan- 
tity of beer, or any alcoholic solution under examination. 
Test the first portion of the distillate for alcohol by the iodo- 
form test, 204. Beer contains from 1-4% alcohol. The 
quantity of alcohol is usually determined from the specific 
gravity of a measured quantity of the distillate. 
LABORATORY QUESTIONS. 
1. What would be a safe flashing point for Texas oil? 
2. Why is a lamp in which oil is low more liable to explode than 
when filled ? 
3. Is kerosene explosive? Insert a lighted match into a beaker of oil, 
and see. 
4. Give the chemical names of chloroform and iodoform? 
5. What is a substitution product ? 
6. What relation does alcohol bear to an alkali ? ORGANIC CHEMISTRY. 
101 
7. For what purposes is absolute alcohol useful ? 
8. When alcohol is in contact with specimens, what change does it 
undergo? How would you preserve a specimen in alcohol? 
9. What is the cause of the blue color of Q1SO4 ? 
10. Write the reaction showing how lime assists in the preparation of 
absolute alcohol ? 
11. How does the preparation of whisky differ from that of alcohol? 
12. What are alcoholic “ tears,” observed in the distillation of alcohol, 
and why formed ? 
206. Preparation of Ether. Into a generator put 20 c.c. of 
alcohol. Keep it cool, and slowly add 10 c.c. of strong 
H2S04. Mix, gently warm, and catch the distillate in a test 
tube surrounded by a beaker of ice and water. The distillate 
will be ether, (C2H5)20, mixed with a little alcohol. Pour 
the distillate on the hand. Note the odor and the cold 
produced. 
Reactions—(C2H5)0H + H2S04 = (C2H5)HS04+ H20, 
Alcohol Acid ethyl sulphate 
(C2H5)OH + (C2H5)HS04 = (C2H5)02+H2S04. 
Alcohol Acid ethyl sulphate Ether 
207. Preparation of Aldehyde. In a generator mix 20 c. c. of 
a solution of potassium bichromate, K2Cr207 and 2 c.c. of 
H2S04. Cool the mixture. Next add 5 c.c. of alcohol, heat, 
and catch several c.c.’s of the distillate in a test tube, cooled 
by being immersed in a beaker of ice and water. The distil- 
late has the sharp odor of ethyl aldehyde, C2H40, and is 
mixed with some alcohol. 
Reactions—K2Cr207 and H2S04 liberate O. 
C2H5(0H) + 0 = C2H40 + H20. 
Alcohol Aldehyde 
Test a few drops by 209-2 for acetic acid. There is none 
present. Set the remainder away, exposed to the air, for some 102 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
time. Aldehyde is slowly oxidized to acetic acid. Test the 
solution for acetic acid by 209-2, and prove its presence. 
Reaction —C2H40 + O = C2H402. 
Aldehyde Acetic acid 
This process illustrates the oxidation of alcohol to acetic 
acid, which is performed in one stage by the mother of vine- 
gar (bacterium aceti). 
208. Tests for Aldehydes. 
1. The Silver Test. Take a solution of AgN03 in a test 
tube. Add 3 drops of NH4OH and a few drops of an alde- 
hyde, as, for example, formaldehyde, CH20, called formalin) 
a powerful non-poisonous preservative and antiseptic. Next 
warm the solution and set it aside. The aldehyde will reduce 
the silver nitrate and deposit a bright mirror of metallic silver 
on the sides of the tube. 
2. The Potassium Test. To a solution of KOH add a 
few drops of an aldehyde and heat gently. A yellow alde- 
hyde resin, having a peculiar odor, is precipitated. 
209. Tests for Acetates. 
1. The Sulphuric Acid Test. Heated with H2S04, acetates 
evolve fumes of acetic acid, H(C2H302). 
2. The Ferric Chloride Test. FeCl3 forms in exactly 
neutral solutions a deep red liquid, due to the presence of 
red Fe(C2H302)3, which when boiled precipitates red oxace- 
tate of iron, FeO(C2H302). 
3. The Acetic Ether 7'est. Strong solutions of acetates 
mixed with H2S04 and a little alcohol, when heated evolve 
the peculiarly fragrant odor of ethyl acetate, or acetic ether, 
1 
2io. The Detection of Mineral Acids in Vinegar. Take a dilute 
solution of methyl violet. Add a drop of acetic acid or ORGANIC CHEMISTRY. 
103 
other organic acid. No change occurs. Now add a few 
drops of acetic acid containing a minute amount of H2S04> 
or any mineral acid. The color immediately changes from 
violet to blue, and to green when the mineral acid is in 
excess. 
211. Preparation of Valerianic Acid. Into a generator put 
20 c.c. of K2Cr207 and 2 c.c. of H2S04. Cool the mixture. 
Next add 7 c.c. of amyl alcohol. Heat, and catch the dis- 
tillate in a cool tube. The substance is composed of a mix- 
ture of valerianic aldehyde, C5H10O, valeric acid and water. 
Cool the generator, pour back the distillate, and distil 
again. The second distillate is purer valerianic acid, 
H(C5H902), with its characteristic odor and acid reaction. 
Reactions—C5Hu(0H)-|-0— C5H10O-|-H2O. 
Amyl Alcohol Valerianic Aldehyde 
QHioO-f-O = C5H10O2. 
Valerianic Aldehyde Valerianic Acid 
212. Preparation of Oxalic Acid. Heat a mixture of 10 
parts of strong HN03 and 2 parts of cane sugar until ni- 
trous fumes cease to be evolved. On cooling, crystals of 
oxalic acid, H2C204, are deposited. On a large scale, oxalic 
acid is prepared by heating sawdust and soda. 
213. Tests for Oxalates. 
1. The Barium Test. BaCl2 slowly ppts. from neutral 
solutions a white ppt. of BaC204, slightly soluble in acetic 
acid, soluble in HN03, HC1 and NH4C1. 
2. The Calcium Test. CaCl2 slowly ppts. white CaC204, 
insoluble in acetic acid, soluble in HC1 and HN03. 
3. The Silver Test. AgN03 ppts. white Ag2C204, soluble in HNO3 
and NH4OH. 
4. The Carbon Monoxide Test. Heated in a test tube with H2S04, 104 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
oxalates without charring evolve CO, which, when ignited, burns at the 
mouth of the tube with its characteristic blue flame. 
Heated alone in a test tube, oxalates without charring evolve CO, and 
the white residue effervesces on addition of HC1. 
214. Tests for Tartrates. 
1. The Calcium Test. CaCl2, after a few moments, ppts. 
white crystalline Ca(C4H406). NH4C1 prevents this pre- 
cipitation. The ppt. is soluble in KOH, but reprecipitated 
on boiling. It is slightly soluble in acetic acid. 
2. The Barium Test. BaCl2 ppts. white Ba(C4H406), 
soluble in HC1 and NH4C1. 
3. The Silver Test. AgN03 ppts. in neutral solution white 
Ag2(C4H40e). This ppt. blackens on boiling, and is soluble in HC1 
and NH4CI. 
4. The Heat Test. Tartrates char when heated alone or with 
H0SO4. 
215. Tests for Citrates. 
1. The Calcium Test. CaCl2 in neutral solution precipi- 
tates perfectly, on boiling, Ca3(C6H507)2. Unlike calcium 
tartrate, this calcium citrate is insoluble in KOH. 
2. The Silver Test. AgN03 ppts. white and, unlike 
silver tartrate, this ppt. does not blacken on boiling. 
3. To detect a Mixture of Tartrates and Citrates. Precipitate the 
mixture with CaCl2, heat, filter and digest the well-washed ppt. with 
cold KOH. Dilute and filter. The filtrate contains the tartrate, which 
is precipitated on boiling. The undissolved residue on the filter con- 
tains the citrate. Dissolve this in NH4C1 solution, filter, and the cal- 
cium citrate will precipitate when boiled. 
LABORATORY QUESTIONS. 
1. How would you detect aldehyde in alcohol? 
2. Can you mention an insoluble normal acetate? 
3. Is acetic ether a proper name for ethyl acetate ? 
4. What is an ester? 
5. What is an ether? What is an alcohol? ORGANIC CHEMISTRY. 
105 
6. What is an aldehyde? 
7. How may you distinguish between HC1 and H2C204 by AgN03 ? 
8. What acid does a Seidlitz powder contain? Test one. 
9. What substance is the best for use to preserve pathological speci- 
mens ? 
10. Show the steps in the change from alcohol to vinegar. 
11. Of what value is brown paper or tea leaves added to dilute 
molasses in vinegar making? 
12. How does oxalic acid aid in removing inkstains? 
13. Why does wine sour when the bottle is not well corked? 
14. Is oxalic acid in pieplant poisonous? Why? 
15. Is there any reason why vinegar should contain a mineral acid? 
16. What relation does chloral bear to aldehyde? Will it give the 
mirror test for aldehydes, 208-1? Try it. 
216. Preparation of Nitrous Ether. In a generator mix 
1 c.c. of H2S04 and 2 c.c. of HN03. Cool the mixture 
thoroughly and add 10 c.c. of alcohol. Add a few pieces 
of broken glass. Boil gently, and collect the distillate in a 
test tube cooled by ice water. Note the odor of ethyl 
nitrite or nitrous ether (C2H5)N02. A solution of this in 
alcohol forms sweet spirits of nitre. 
Reaction— 
2(C2H5)0H + HN03 = (C2H5)N02+C2H40 + 2H20. 
Alcohol Ethyl Nitrite Aldehyde 
217. Preparation of Acetic Ether. In a generator mix 2 g. 
of dry sodium acetate, 10 c.c. of alcohol and 2 c.c. of 
H2S04. Add a few pieces of broken glass. Heat gently, 
and collect the distillate in a test tube surrounded by ice 
and water. Note the odor of ethyl acetate or acetic ether, 
(C2H5)(C2H302), mixed with some alcohol. 
Reaction— 
2(C2H5)0H+2Na(C2H302)+H2S04=2C2H5(C2H502)+Na2S04+2H20 
Alcohol Sodium Acetate Ethyl Acetate 
218. Preparation of Amyl Acetate. In a generator mix 2 g. 
of dry sodium acetate, 5 c. c. of amyl alcohol and 2 c.c. of 106 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
H2S04. Add a few pieces of broken glass. Heat gently, and 
collect the distillate in a test tube cooled by ice and water. 
Note the odor of the distillate or amyl acetate, C5Hn(C2H302), 
like pears. It is an example of the fruit essences, and is 
used by confectioners. 
Reaction— 
2(C5H11)OH+2Na(C2H302)+H2S04=2C5H11(C2H:!02)+NaoS04+2H20 
Amyl Alcohol Sodium Acetate Amyl Acetate 
219. Preparation of Amyl Nitrite. Put 3 c.c. of amyl alcohol 
in a test tube. Through this pass red nitrous fumes of N203 
from a generator containing hot HN03 and starch. Keep 
the alcohol cool by immersing it in ice water. Impure amyl 
nitrite is formed (C5Hu)N02. Note its characteristic chok- 
ing odor. 
Reaction—2 (C5HU) OH + N203-2(C5H11)N02 + H20. 
Amyl Alcohol Amyl Nitrite 
220. Preparation of Benzoic Acid. Place in a dry test tube 
a small piece of gum benzoin. Gently heat the tube, and 
note the small white needles of benzoic acid which sublime 
on the cool part of the tube. 
221. Preparation of Benzene. Place in a test tube an intimate 
mixture of equal parts of benzoic acid and quicklime, and 
apply heat. Note the odor of the benzene vapor evolved, 
and compare it with the commercial article. On a larger 
scale these vapors may be easily condensed. 
Reaction—H(C7H502) + CaO = C6H6 + CaC03. 
Benzoic Acid Benzene 
222. Preparation of Nitro-benzene. In a large test tube mix 
io c.c. of H2S04 and 5 c.c. of HN03. Cool the mixture, add 
a drop of benzene, shake, and cool the tube. Continue this 
process until 20 or 30 drops are added, keeping the tube cold. 
Next slowty pour the whole into a beaker of water. Impure ORGANIC CHEMISTRY. 
107 
nitro-benzene, C6H5N02, will sink to the bottom in the form 
of a brownish yellow oil, called the “essence of mirbane, ” or, 
from its odor, artificial oil of bitter almonds. 
Reaction—C6Hg + HN03 = C6H5N02 + H02. 
Benzene Nitro-benzene 
223. Preparation of Aniline from Acetanilid. Powder a piece 
of solid NaOH the size of a grain of corn. Mix this with 
about 1 g. of acetanilid and put it into a test tube. Apply 
heat. Notice the oily globules that arise as the mixture 
melts. Sudden solidification will occur. Then tip up the 
test tube so that the aniline oil may run out. Catch it in 
another test tube containing about 3 c.c. of water. Keep 
heating the solidified substance as long as the oil continues 
to drip from the tube. In the second tube a good sized glob- 
ule. of white aniline oil, C0H5NH2, is obtained. Note the 
odor, and compare it with that of the commercial article. 
Reaction— 
(C6H5)(NH)(C2H30) + NaOH = C6H5NH2 + Na(C2H302>. 
Acetanilid Aniline Sodium Acetate 
224. Color Reaction of Aniline. Take half a test tube of 
water. Into it put a drop of aniline prepared in the above 
experiment. Shake well and add 3 drops of a clear solution 
of bleaching powder in water. A violet color develops, due 
to the formation of an aniline dye. 
225. Preparat'on of Rosaniline. Take about 2 g. of HgCl2 in 
a test tube. Add 3 drops of aniline oil. Heat gently until the 
mass assumes first a green and then a dark purple hue. Cool 
the tube, and add a little alcohol and two drops of HC1. Stir 
it up and pour it into a beaker of water. The purple color 
resulting is due to the presence of rosaniline hydrochloride, 
one of the most important aniline dyes. 108 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
226. Tests for Carbolic Acid or Phenol, C6H5OH. 
1. The Ferric Chloride Test. FeCl3 colors moderately 
concentrated aqueous solutions dark violet. 
2. The Bromine Test. A drop of bromine, even in very 
dilute solutions, ppts. yellowish white tri-bromo-phenol, 
C6H2Br3(OH). 
3. The Hypochlorite Test. A pinch of bleaching powder 
added to an ammoniacal solution of phenol yields a green 
coloration. 
4. Certain Pine Shavings moistened with HC1, and touched 
with a solution of phenol, turn blue when exposed to the air 
for a time. 
227. Preparation of Picric Acid. Take 5 c.c. of dilute HN03 
in a beaker. Add 2 c.c. of carbolic acid. Cool the mixture. 
Add 10 c.c. of strong HN03, drop by drop. Boil the solution 
for five minutes, adding a little strong HNOg, drop by drop, 
if the dark, oily phenol seems to float after some boiling. 
Pour the whole solution finally into 25 c.c. of water. Set 
aside and decant the liquid from the yellow crystals de- 
posited. Wash these with a few drops of water. Decant, 
and notice the yellow solution of picric acid. Dry the crys- 
talline picric acid, CGH2(N02)3(OH). Notice that these dry 
crystals explode when dropped on a very hot surface or 
introduced into a flame. 
Reaction—C6H5(OH) -f 3HN03 = C0H2(NO2)3OH + 3H0O. 
Phenol Picric Acid 
228. Tests for Antipyrin. 
1. The Ferric Chloride Test. FeCl3 turns solutions of 
antipyrin blood red. 
2. The Nitrous Acid Test. Dilute HN03, having dissolved 
in it a little KN02, turns solutions of antipyrin green. 
3. The Iodine Test. I dissolved in KI solution forms, in 
solutions of antipyrin, a brick-red ppt. ORGANIC CHEMISTRY. 
109 
1. Why is sweet spirits of nitre apt to be acid ? 
2. How might nitrous acid be present in sweet spirits of nitre ? If 
possible, test for its presence by 93, and write the reactions showing its 
formation. 
3. Why would old sweet spirits of nitre turn green on addition of 
antipyrin ? 
4. To what class of chemical compounds do fruit essences belong ? 
Do they occur in nature ? 
5. Ethyl butyrate is pineapple flavor. Write its formula, and invent a 
method for its preparation. See 237. 
6. For what is benzene used ? 
7. What is the difference between benzene and benzine? 
8. Of what two substances is acetanilid composed ? Outline a 
method of preparing acetanilid. 
9. For what is amyl nitrite valuable? 
10. What compounds of benzoic acid are used in medicine ? 
11. Why is H0SO4 used in the preparation of nitro-benzene ? 
12. Of what is smokeless powder composed? 
13. Why does HNO3 turn the skin yellow? 
14. Is nitro-benzene poisonous ? 
15. Is carbolic acid an acid? Try litmus paper. 
16. What is a carbolate ? 
17. What is the significance of the termination “ ol ” in phenol. 
18. Is aniline poisonous? 
LABORATORY QUESTIONS. 
FATS AND OILS. 
229. Solution of Fats. Dissolve a small amount of the dif- 
ferent oils and fats found on the side table in small amounts 
of the following solvents : Boiling alcohol, benzol, gasolene 
carbon disulphide, ether, etc. 
230. Emulsion of Fats. Shake a few drops of fat with half a 
test tube of water. Note that on standing the oil rapidly 
rises to the surface. Repeat the process with 
1. A few drops of alkali. A white emulsion is formed. 110 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
2. A few drops of soap solution. A white emulsion is 
formed. 
3. A solution of white of egg. A white emulsion is formed. 
4. A solution of gum arabic. A white emulsion is formed. 
Examine an emulsion under the microscope. 
231. Saponification of Fats—Hard Soap. Take 10 c.c. of 
castor oil in a beaker. Add an equal quantity of a solution 
of NaOH in alcohol. Stir it until a firm mass of soap is 
produced. This may be melted and poured into a mold, 
or used as it is. It will produce a good lather. When a 
solution of alkali in water is used, several hours’ boiling is 
required. The same action occurs in a few moments with 
an alcoholic solution of alkali. Hence this is the quickest 
laboratory method. 
Illustrative reaction— 
C3H5(C18H3502)3-f 3^aOH = C3H5(0H)3-{-3Na(C18H3502). 
Stearin Glycerine Sodium Stearate 
232. Saponification of Fats—Soft Soap. Repeat the above 
process, using KOH in place of NaOH. A potassium, or 
soft soap, is formed. 
233. Preparation of Insoluble Soaps. Make up a beaker full 
of a strong solution of the soft soap formed above. Half 
fill several test tubes with this. Add the following reagents, 
and shake the tubes. 
1. CaCl2 ppts. an insoluble white lime soap. No lather 
forms when shaken. 
2. Repeat No. 1, first adding a solution of Na2C03 before 
CaCl2. The lime is first pptd. as CaC03. No lime soap 
forms in the softened water, and it lathers when shaken. 
3. MgS04 ppts. insoluble white magnesium soap. 
Reaction—CaCl2-j-Na2C03 = 2NaCl-|-CaC03. ORGANIC CHEMISTRY. 
111 
4. Pb(C2H302)2 ppts. insoluble white lead soap (lead 
plaster). 
5. FeCl3 ppts. insoluble brown ferric soap. 
6. FeS04 ppts. insoluble greenish ferrous soap. 
7. CuS04 ppts. insoluble blue copper soap. 
234. Preparation of Lead Plaster. Heat in an evaporating 
dish, with constant stirring, 3 parts of olive oil, 5 parts of 
water, and 1 part of litharge, PbO, until a yellowish white, 
tenacious mass of lead soap is obtained. It is the same 
substance formed in 233-4. 
235. Preparation of Fatty Acids. Boil in an evaporating 
dish a mixture of soft soap and water. Add HC1 to excess. 
Reheat and set aside. Remove the light, fatty substance 
from the surface. Wash it in water. It is neither fat nor 
soap. It has no soapy taste. It is a mixture of fatty acids 
used in the manufacture of candles. Glycerine, KC1 and 
HC1 remain in the solution. 
236. Preparation of Butter Soap. Put a teaspoonful of 
butter in a beaker. Boil it with a little dilute aqueous 
solution of KOH, adding repeatedly small amounts of alkali 
of increasing strength. After boiling and stirring for some 
time, remove from the fire and examine the soft butter 
soap. It will produce a lather. 
237- Separation and Identification of Butyric Acid. Mix the 
butter soap formed above with a little water. Place the 
mixture in a generator. Add to c.c. of H2S04. The fatty 
acid may be seen rising to the top. Heat, and collect 5 or 
10 c.c. of the distillate in a cooled tube. It will contain 
butyric acid, have a rancid odor and an acid reaction to 
litmus paper. Heat this distillate with a little alcohol and 
2 c.c. of H2S04. Note the odor of ethyl butyrate, C2H5- LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
112 
(C4H702), which is used as artificial pineapple flavor. 
“Oleo” treated thus contains only traces of volatile fatty 
acids in the distillate, and yields no ethyl butyrate. 
238. Identification of Butter and “Oleo.” The principle 
of the above reaction may be more rapidly applied thus : 
Place in two test tubes equal quantities of butter and oleo- 
margarine. Add 5 c.c. of a strong alcoholic solution of 
KOH to each. Warm gently, and notice the difference in 
odor. The “oleo” has the odor of alcohol simply, the 
butter the. odor of pineapple, by the formation of ethyl 
butyrate from the alcohol and butyric acid. “Oleo” which 
has been churned with milk in the process of manufacture 
may yield slight traces of butyric ether. 
239. Decomposition of Glycerine. Mix a few drops of glycer- 
ine and H2S04 in a test tube. Heat, and note the sharp odor 
of acrolein. Any fat containing glycerine yields the same 
reaction. 
Reaction—(C3H5)(0H)3=C3H40-|-2H20 
Glycerine Acrylic Aldehyde 
240. The Borax Test for Glycerine. Mix with a pinch of 
borax a few drops of suspected glycerine, which must be neu- 
tral and free from ammonium salts. Heated on a platinum 
wire, the mixture immediately tinges the Bunsen flame pale 
green, due to the liberation of boric acid by the glycerine. 
LABORATORY QUESTIONS. 
1. Can castor oil be dissolved in benzine? 
2. Can olive, castor and cod-liver oils be distinguished by being 
touched with H0SO4? 
3. Why does an alkali emulsify fats? 
4. Why does albumin water emulsify fats ? 
5. Does the character of the fat have any influence on the hardness 
of soap? ORGANIC CHEMISTRY. 
113 
6. Why does an alcoholic solution of an alkali more quickly saponify 
fats than an aqueous solution ? 
7. Write the reaction involved in the formation of a calcium soap. 
8. Why does hard water not lather soap ? 
9. Why, when an alkali is added to water, does it often become soft ? 
10. Why is one soap hard and another soft ? 
11. Is soap a salt? 
12. Why is NaCl often added to a kettle of soap after it is made? 
13. What lye is usually used in preparing “home-made” soaps? 
14. Resin contains 3 fatty acids. Would it saponify with NaOH ? 
15. What is lead plaster? 
16. Which are more stable, the fats of “ oleo ” or butter? 
17. Write the reaction involved in the preparation of fatty acids. 
18. In what is oleomargarine superior to butter? 
19. Chemically, what is a fat? 
20. What is glycerol ? What does the termination “ol ” signify? 
CARBOHYDRATES. 
241. Preparation of Corn Starch. Finely pulverize some corn 
in a mortar. Add water from time to time, and strain the 
milky liquid off through a cloth. Set it aside until the white 
sediment can be separated by decantation. Collect and dry 
this white corn starch, (CGH10O5)n, on filter paper. 
242. Appearance of Starch Granules. Examine under the 
microscope a thin section of potato. Notice how the starch 
granules lie packed within each cell. Touch the section with 
a drop of dilute iodine solution. Note that the granules turn 
blue, but the cellulose wall appears unchanged or slightly 
yellow. Examine the prepared microscopical specimens of 
potato, arrow root, corn, rice, and other starches, noting the 
difference in form and size of the granules. 
243. Preparation of Starch Paste. Mix a little powdered 
starch with water to a thin milk. Pour this slowly into a 
beaker of boiling water with constant stirring. The milki- 114 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
ness disappears, and the whole forms apparently a translucent 
homogeneous solution. 
244. The Iodine Test for Starch. A few drops of a solution 
containing free iodine strike with starch paste a deep blue 
color, from the formation of starch iodide. This color disap- 
pears on heating and reappears on cooling, unless the heat 
has been high enough to volatilize the iodine. 
245. Properties of Glucose. Examine commercial glucose, 
or grape sugar (dextrose). It is not as sweet as cane sugar. 
Make a solution of glucose, and set it aside for further experi- 
ments. Add H2S04 to cold solutions of cane sugar and 
grape sugar. Heat to boiling, and note the charring of the 
cane sugar, while the glucose remains nearly unaltered. 
Repeat the experiment, using KOH. The cane sugar is only 
slightly affected, while the glucose assumes a dark brown 
color, due to the formation of caramel. 
246. Fehling’s Test for Glucose.1 In a test tube take some 
Fehling’s glycerine solution. Heat it just to boiling, and add 
a few drops of liquid containing glucose. Again bring the 
mixture to the boiling point, and set it aside. If glucose was 
added in any appreciable quantity, a yellow or brick-red ppt. 
of cuprous oxide, Cu20, will be found in the bottom of the 
tube. When sufficient glucose is added the copper will all 
be thrown down and the supernatant liquid will be colorless. 
247. Detection of Glucose in Fruits and Candies. Soak a bruised 
raisin in water and test the solution for glucose. Dissolve a 
bit of candy in water and test the solution for glucose. Glu- 
cose will be present in both instances. 
248. Action of Various Sugars on Fehling’s Solution. Examine 
Noth i. The composition of Fehling’s glycerine test will be found under 348, Note i, 
also other tests for glucose under urinalysis, 346-353. ORGANIC CHEMISTRY. 
115 
the following sugars. Make a solution of each, and test as 
for glucose by Fehling’s test. Verify the following conclu- 
sions : 
(1) Sucrose (cane sugar). No reducing power. 
(2) Dextrose (grape sugar). Reducing power. 
(3) Lactose (milk sugar). Reducing power. 
(4) Maltose (malt sugar). Reducing power. 
249. Preparation of Invert Sugar. Make a dilute solution of 
cane sugar. Add a few drops of acid, and warm for 10 min- 
utes. Test some of this solution for glucose. Cane sugar 
takes up a molecule of water and splits into two molecules, 
one of which is dextrose, or dextro-rotary, the other laevulose, 
or laevo-rotary. 
Reaction—C12H22011-fH20 = 2(C6H1206) 
Cane Sugar Invert Sugar 
250. Action of Sugar on Polarized Light. Examine with the 
polariscope a solution of cane, malt, milk, or grape sugar. 
Note that they are dextro-rotary. Examine a solution of in- 
vert sugar, and decide on its action on the polarized ray. 
251. Preparation of Barley Sugar and Caramel. In an evapo- 
rating dish very slowly heat some dry cane sugar. It melts 
to a clear yellowish liquid. When melted, stir and cool. 
Barley sugar is formed. Save a sample. Heat the remainder 
until it is of a dark brown color. Caramel is formed, which 
is sugar less a molecule or two of water. It is used for color- 
ing liquors, etc. Test solutions of both these products for 
glucose, and prove its presence. 
252. Conversion of Starch to Dextrine. Heat a pinch of dry, 
finely powdered starch in an evaporating dish over a very slow 
fire, with continuous stirring until it all turns brown, but does 
not char. This occurs at about 250° C. Dextrine or British 116 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
gum is formed, C6H10O5. When cool, boil with a little water, 
and filter. The solution should be of a reddish color, and if 
all starch has been transformed to dextrine, the solution 
strikes a pinkish and not a blue color with iodine. 
This is an example of the splitting of the starch molecule into soluble 
starches or dextrines, which action is induced by heat, acids and digestive 
ferments. It may be continued through a series of products, ending at 
last in the formation of sugar, as seen in the next exercise, and in 282, 
under Saliva, where the color reactions of the intermediate products with 
iodine are given. 
253. Conversion of Starch to Glucose. Boil a beaker of starch 
paste, prepared as in 243, with 10 c. c. of H2S04 for an hour 
or more, adding water from time to time, if necessary, until 
a drop of it ceases to give a color with iodine, showing the 
conversion of all the starch. Add marble dust until effer- 
vescence ceases, which neutralizes any free acid remaining. 
Filter the solution. Notice its sweet taste. Test it, and 
prove the presence of glucose. It may be evaporated, and 
will sometimes crystallize. This is the method of preparing 
commercial glucose from corn, and is much used in syrups, 
candies, etc. 
254. Conversion of Starch to Maltose. In a test tube warm 
to blood heat a dilute solution of starch paste. Pound up 
some malted barley—i. e., barley which has begun to sprout, 
and dried and heated until the germ is killed. Mix this 
with water. Grind it up and filter. Add some of this clear 
solution to the warm starch paste. After some minutes, test 
and prove the presence of maltose by Fehling’s test. Prove 
the conversion of all the starch by a drop of iodine solution. 
Illustrative reaction—(CcH10O5)3+2H2O= C12H220u+C8H1206. 
Starch Maltose Dextrose 
255- Preparation of Parchment Paper. Dip a piece of unsized ORGANIC CHEMISTRY. 
117 
paper in strong H2S04 for about 15 seconds, then wash it 
thoroughly with water. Notice that the paper has become 
stronger and more translucent. Its fibers have become col- 
loidal, and it may be used for dialysis, as it will allow only 
the molecules of crystalline substances to penetrate its pores, 
and the simpler proteid molecules, like peptones, etc. 
256. Preparation of Collodion. Make a mixture of 15 c.c. of 
strong H2S04 and 20 c.c. of strong HN03 in a beaker. Cool 
the mixture and immerse in it a piece of shredded absorbent 
cotton. Macerate 15 minutes. Wash the cotton free from 
acids under the tap. Press it between filter paper and dry 
it. Notice that when thoroughly dry a portion burns in- 
stantly, leaving little ash. If the nitration has been exactly 
performed, di-nitro-cellulose is produced. This is pyroxylin, 
or soluble cotton. It dissolves in a mixture of 3 parts of 
ether and 1 of alcohol, forming collodion. 
Illustrative reaction— 
C6H10O5+2HNO8=C6H8O8(NO8)2+2H2O. 
Cellulose Di-nitro-cellulose 
Gun-cotton is more explosive, and consists of a mixture of higher 
nitrates of cellulose, produced by more prolonged action of HN03. It 
is insoluble in a mixture of alcohol and ether. 
Illustrative reaction—C6H1o05-f-3HN03=C6H702(N03)3+3H20. 
Cellulose Tri-nitro-cellulose 
LABORATORY QUESTIONS. 
1. Can the source of starch be determined by the form of its granules p 
2. Write the formulas and show the relations of cellulose, starch and 
the various sugars. 
3. What is a carbohydrate ? 
4. What is the nature of the change when cane sugar becomes glucose ? 
5. Why is vinegar, cream of tartar, or lemon juice used in candy 
making? 
6. In how many ways may starch be converted into glucose? 
7. Ought glucose to be unhealthful ? 118 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
8. For what is dextrine used ? 
9. How does a potato sprout bring its insoluble starch up to its leaves ? 
10. Why is maple sap sweet in the spring ? Why does it lose its sweet- 
ness when the leaves start ? 
11. What does malt extract contain? Is its nutritive value diminished 
by fermentation ? 
12. Could saw-dust be made available for food ? 
13. Why do fruits sweeten as they ripen, and lose their sweetness when 
they decay ? 
14. Why is invert sugar so called ? 
15. What is malt? LABORATORY EXERCISES 
IN 
PHYSIOLOGICAL CHEMISTRY 
INCLUDING THE 
DIGESTION, BLOOD AND MILK PHYSIOLOGICAL CHEMISTRY. 
121 
PHYSIOLOGICAL CHEMISTRY. 
THE DETECTION OF PROTEIDS IN SOLUTION. 
257. The Xanthoproteic Color Reaction. Take half a test 
tube of albumin solution. Add 5 c.c. of concentrated HN03. 
Warm, and notice the yellow precipitated albumin. Divide 
in two test tubes. Add, until alkaline, to the one NH4OH, 
to the other KOH. The yellow solution turns orange in both 
instances. 
258. The Biuret Color Reaction.1 Take half a test tube of 
albumin solution. Add two drops of dilute CuS04 and 5 c.c. 
of KOH. A violet tint appears, which deepens on boiling. 
With peptones the color is rose-red. 
259. Millon’s Precipitation Reaction. Take half a test tube 
of albumin solution. Add a few drops of Millon’s reagent.2 
A white ppt. falls, becoming reddish on boiling. If only 
traces of albumin are present, the solution becomes slightly 
red. 
260. The Sodium Sulphate Precipitation Reaction. Take one- 
third of a test tube of albumin solution. Render it acid 
with acetic acid. Add an equal volume of concentrated 
Na2S04 solution. When boiled, a white ppt. falls. This 
test throws down all proteids except peptones. The salt 
and acid do not interfere with the tests for peptones in the 
solution. 
261. The Ferrocyanide Precipitation Reaction. Render a 
Note i. Called Biuret because this color also forms from biuret, C2H5N3O2, a 
substance obtained by heating urea. 
Note 2. Millon’s reagent is prepared by dissolving 1 part of metallic mercury in 
2 parts of strong HN03, adding twice its volume of distilled water, setting aside until 
settled, and decanting the clear solution. 122 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
solution of albumin strongly acid with acetic acid. Add a 
few drops of a fresh, strong K4FeCy6 solution. A milk- 
white precipitate falls. This reagent ppts. all proteids 
except peptones and some forms of albumose. When acetic 
acid is added after the K4FeCy6, mucin is not precipitated. 
262. The Tannic Acid Precipitation Reaction. Take half a 
test tube of albumin solution. Add 1 c.c. of a strong solu- 
tion of tannin. A white precipitate falls. Tannic acid 
reacts with all proteids. 
263. The Picric Acid Precipitation Reaction. Take half a 
test tube of albumin solution. Add a few drops of a strong 
solution of picric acid. A yellow ppt. comes to view, dis- 
solving to a dark color when heated with KOH. Picric acid 
ppts. all proteids. 
264. The Absolute Alcohol Precipitation Reaction. Take one- 
third of a test tube of albumin solution. Render it acid 
with acetic acid. Add an excess of absolute alcohol. A 
ppt. falls. This reagent precipitates all proteids, including 
peptones. 
EXAMINATION OF THE VARIOUS PROTEIDS. 
CLASS I.—ALBUMINS. 
265. Preparation of Egg Albumin. Take an egg. Break a 
small hole in one end of the shell. Pour the white into a 
beaker, leaving the yolk for future examination. Half fill 
the beaker with water. Stir with a glass rod, breaking up 
the albumin Filter through a piece of muslin, 
and keep the solution for the following reactions. 
Albumins are proteids soluble in water and coagulated by heat. 
266. Precipitation of Albumin by Heat. Boil half a test tube PHYSIOLOGICAL CHEMISTRY. 
123 
of albumin water. Notice the coagulation. The coagulum 
does not dissolve on addition of HN03. 
267. Temperature of Coagulation. Extract a little more of 
the undiluted white of egg from the shell. Place it in a 
test tube, insert a thermometer, and set the whole in a 
beaker of water. Warm the beaker slowly. Note the tem- 
perature at which the albumin shows the first signs of opal- 
escence (about 590 C.), and the point of total coagulation 
(about 730 C.). 
268. Precipitation of Metallic Albuminates. Prepare three 
test tubes of albumin solution. Add to separate tubes solu- 
tions of CuS04, AgN03, and HgCl2. Copper, silver and 
mercury albuminates fall. Compare them with the soap 
ppts. formed in 233. 
CLASS II.—PEPTONES. 
Peptones are proteids soluble in water, but not coagulated by heat. 
Albumoses are substances between albumins and peptones. 
269. Action of Heat and Reagents. Using the prepared 
solution of peptones, confirm the following reactions : 
1. Not coagulated by heat. 
2. Not pptd. by adding NaCl. 
3. Not pptd. by acids or alkalies. 
4. Not pptd. by Na2S04, as in 260. 
5. Not pptd. by K4FeCy6, as in 261. 
6. Pptd. by tannic acid, as in 262. 
7. Pptd. by absolute alcohol, as in 264. 
8. Yields the rose-red Biuret reaction, 258. 
CLASS III.—GLOBULINS. 
Globulins are proteids insoluble in water, soluble in dilute NaCl. 
Solutions are coagulated by heat. Among the most important are: 124 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
Vitellin, crystallin (globulin), myosin, fibrinoplastin (paraglobulin), and 
fibrinogen (metaglobulin). 
270. Preparation and Detection of Vitellin. Stir up the yolk 
of the egg saved, after washing it as carefully as possible 
from the white. Put 3 c.c. of yolk in a test tube. Shake 
well with half a test tube of ether several times. Allow the 
yellowish ether to rise each time, and pour it into an evapo- 
rating dish. The ether largely dissolves the fatty matters. 
Impure vitellin remains. Very gently warm the tube, and 
set it aside until the smell of ether disappears. Add water. 
The vitellin does not dissolve. Next add a pinch of NaCl. 
Vitellin dissolves to a milky solution. Filter, and apply the 
Heat (266), the Xanthoproteic (257), and the Biuret (258), 
reactions. 
271. Examination of the Fatty Matter of the Yolk. Evapo- 
rate the ether solution in the evaporating dish very cau- 
tiously, lest the ether take fire. In case it should, cover the 
dish quickly with a damp cloth, which will extinguish the 
flame. A yellow oil is left. Pour a few drops into water. 
Globules of fat are formed. Heat the remainder with a few 
drops of HN03. The solution is first colored blue, then 
fades to green, and becomes colorless. Now add a little 
water and a drop of KCyS solution. A reddish color proves 
the presence of iron. 
272. Preparation and Detection of Crystallin. Extract the 
crystalline lens from the eye of an ox. Thoroughly grind it 
up in a mortar with 10 c.c. of water, which will dissolve 
albumin. Filter, and grind the residue with 10 c.c. of a 
10% salt solution. The crystallin dissolves. Filter, and 
confirm its presence by Millon’s test (259), the Biuret test 
(258), and the Heat test (266). 
273* Preparation and Detection of Myosin. Soak a table- PHYSIOLOGICAL CHEMISTRY. 
125 
spoonful of finely chopped lean meat in a beaker of water 
for 10 minutes. Squeeze out the juice through a wet cloth, 
and test the liquid for albumin by Millon’s reaction (259.) 
Wash the cloth. Repeat the digestion several times, until 
the water no longer yields much, if any, ppt. with Millon’s 
reagent, showing the removal of serum albumin. Now soak 
the washed meat in a 10% salt solution. Strain the liquid. 
Filter, and test for myosin by Millon’s reagent and a few 
other tests for proteids (257-264). 
Fibrinogen a?id Fibrinoplastin (310), may be similarly pre- 
pared, but the process is too tedious for the time allowed. 
CLASS IV.—DERIVED ALBUMINS. 
Derived albumins are proteids insoluble in water, soluble in dilute 
acids or alkalies. Solutions not coagulated by heat. 
274. Preparation of Acid Albumin. Take half the white of 
an egg. Add 10 drops of glacial acetic acid. Whip them 
well together for some minutes until a gelatinous mass of 
acid albumin forms. Dissolve this in half a beaker of warm 
water. Filter, and confirm the following reactions for solu- 
tions of acid albumin : 
1. Not coagulated by heat. 
2. Precipitated when exactly neutralized by NaOH. 
3. This last ppt. is dissolved by an excess of alkali. 
275. Preparation of Alkali Albumin. Take half the white of 
an egg. Add 15 drops of strong KOH solution. Whip them 
well together until a gelatinous mass of alkali albumin is 
formed. Dissolve this in warm water. Filter, and confirm 
the following reactions for solutions of alkali albumin : 
1. Not coagulated by heat. 
2. Precipitated when exactly neutralized by HC1. 
3. This last ppt. is dissolved by an excess of acid. 126 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
276. Preparation of Syntonin (muscle acid albumin). Wash 
a tablespoonful of lean chopped muscle until proved by 
Millon’s reagent to be free from serum albumin, as in 273. 
Digest the washed meat in a 0.2% HC1 solution. Strain 
the solution through cloth. Filter, and confirm the follow- 
ing reactions for solutions of syntonin : 
1. Not coagulated by heat. 
2. Precipitated when exactly neutralized by NaOH. 
3. Yields the Millon’s and Biuret reactions. 
Casein, sometimes classed as an alkali albumin, will be 
considered under Milk, 320. 
Fibrin is a proteid insoluble in water, swollen by salt solutions, slowly 
soluble in dilute acids and alkalies. Solutions are coagulated by heat. 
Fibrin will be examined under Blood, 305. 
CLASS V.—FIBRIN. 
Proteids are insoluble in water; insoluble in dilute acids or alkalies, 
but decomposed by them when heated. 
CLASS VI.—COAGULATED PROTEIDS. 
277. Preparation and Reaction of Coagulated Proteids. Coagu- 
late some albumin solution by heat. Use portions of this 
coagulum to confirm the following reactions. 
1. It is insoluble in water. 
2. It yields the Xanthoproteic, Biuret and Millon’s 
reaction. 
3. It is changed to acid and alkali albumin by heating 
with acids and alkalies. 
Lardacein, or amyloid substance, is a proteid insoluble in water, salt 
solution, dilute acids or alkalies, and unacted upon by digestive ferments. 
Iodine stains it reddish brown. 
CLASS VII.—LARDACEIN. PHYSIOLOGICAL CHEMISTRY. 
127 
Albuminoids are substances containing N, related to proteids, but not 
answering all proteid reactions, and yielding different decomposition 
products. Among the principal albuminoids are collogen (ossein), 
chondrin, elastin, gelatin, keratin, nuclein, mucin and spongin. 
CLASS VIII.—ALBUMINOIDS. 
LABORATORY QUESTIONS. 
1. What effect does heating have on protoplasm ? 
2. What is an albumose? 
3. What is lardacein? 
4. What is an albuminoid ? 
5. What is glue? Is it a proteid? To what class does it belong? 
6. What proteids could a neutral, boiling meat extract contain? 
7. Does beef tea contain starch or sugar? Test, if possible. 
8. Why are not peptones suitable for food ? Taste an artificial diges- 
tion, and see. 
9. If some proteids were dissolved by ice water, what would be the 
effect of w'arming the soup? 
10. Would salt water extract more nutritive properties from beef than 
fresh water? 
11. Name a wide-spread metallic compound of a proteid. Where have 
you dealt with it under the head of proteids? 
12. In testing urine for albumin, would it be wise to select a test react- 
ing for all proteids? 
13. Select from the general tests for proteids the one best adapted to 
detect serum albumin, and that only, in the urine. 
14. What forms of albumin would dialyze in the stomach, and what 
forms in the intestines ? 
15. Why is the blood advantageously saline and alkaline ? 
16. What is a nucleo-albumin ? 
278. Detection of Sulphocyanides in Saliva. Put a clear drop 
of saliva on a white porcelain surface. Touch this with a 
drop of dilute FeCl3. A light claret color is usually pro- 
duced, especially on standing, which is not destroyed by a 
SALIVA. 128 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
solution of HgCl2. This test proves the presence of a salt of 
sulphocyanic acid, HCyS. 
279. Action of Ptyalin on Starch. Prepare a dilute solution 
of starch paste, 243, and collect a few c.c. of saliva. Test 
both by Fehling’s solution, and prove that neither contains 
glucose. Mix the two, warm to blood heat for 10 minutes, 
after which prove the presence of glucose by Fehling’s test. 
280. Reaction of Saliva. Into a few c.c. of clear filtered 
saliva put a few drops of violet litmus solution. Compare it 
with a similar test made with water. If the saliva is alkaline, 
a deeper hue results with the saliva. In rare cases the action 
may be acid. It is most alkaline at the height of the flow, 
amounting to about that of a .08°]0 Na2C03 solution. 
281. Inactivity of Ptyalin in Acid Solution. Repeat experi- 
ment 279, rendering the starch slightly acid with acetic acid 
before adding the saliva. At the expiration of 10 minutes 
Fehling’s test shows little or no glucose, which points to the 
inactivity of ptyalin in acid solutions. 
282. Determination of the Diastatic Value of Saliva.1 Take io 
c.c. of the standard starch solution,2 in a beaker, and dilute 
with 90 c.c. of water. Warm to 40° C. Add 1 c.c. of clear, 
carefully-measured saliva.3 The whole is kept stirred. At 
the end of every minute a drop is removed to a white porce- 
lain surface and touched with a drop of dilute iodine solution. 
Note i. This method may be applied to the determination of the diastatic value of 
infusions of malt or diastase, etc. 
Note 2. The standard starch solution is prepared by taking log. of starch, making it 
into starch paste, and diluting with water until the whole measures 1,000 c.c. This solu- 
tion must be used when fresh, and well shaken. Each c.c. contains .01 g. of starch. 
Note 3. The experiment must be tried several times, and the amount of saliva used 
diminished or increased until the achromic point is reached within 4-6 minutes, otherwise 
the results are not reliable. PHYSIOLOGICAL CHEMISTRY. 
129 
The blue color at first formed passes through violet, pink, 
brown and yellow, and at last reaches the colorless or 
achromic point, when the conversion of the starch has com- 
pletely passed through amylo-, erythro-, achroo- and malto- 
dextrin to maltose. 
RESULT OF AN ACTUAL EXPERIMENT. 
io c.c. of starch, 90 c.c. of water, 0.2 c.c. of saliva, temp. 40° C. 
Time. 
Reaction with Iodine. 
4-15 P- M 
Begun. 
05 
4.10 “ 
Blue. 
2 
4-17 “ 
Violet. 
c 
4.18 “ 
Brown. 
4-19 “ 
Yellowish brown. 
* 
4.20 “ 
Pale yellow. 
.4.21 “ 
No color, achromic point. 
The diastatic value may then be calculated, showing how 
much starch solution 1 c.c. of saliva will change in 5 minutes 
at the temperature of the experiment. Thus : 
The diaStatic Value = No_ of c.c.°of saliva X No. of minutes 
or in the example X f = 41.6 c.c. 
LABORATORY QUESTIONS. 
1. Under what circumstances might saliva be acid? 
2. Does the presence of cyanides in saliva seem to indicate the break- 
ing down of proteids to supply the salivary secretion ? 
3. How much dry starch would 1 c.c. of the saliva in the example 
change into maltose in 5 minutes ? 
4. What seems to be the chief use of saliva ? 
5. Is the activity permanently destroyed by rendering ptyalin acid ? 
Neutralize the acid in experiment 281, and see if the ptyalin resumes its 
amylolytic activity. 
6. Will saliva answer the tests for proteids ? If so, to what is this 
principally due? 
7. What evidence do the teeth show that the saliva contains inorganic 
salts ? 130 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
8. If possible, dry some saliva. Ignite the residue, and test it for 
chlorides, carbonates and phosphates. 
9. Are medicinal substances excreted in saliva ? See 293. 
10. Most enzymes are soluble in glycerine. Would a pig's salivary 
gland, pounded and soaked in glycerine, yield an active amylolytic solu- 
tion ? If possible, try it. 
11. Is any student found whose saliva does not contain ptyalin ? If so, 
examine his saliva at different times in the day. Assign a cause, based 
on health, constitution and habits. 
12. What influence would tea have on pepsin and enzymes in general ? 
13. Why does saliva bubble? 
14. What is the cause of the alkalinity of the saliva ? 
GASTRIC JUICE. 
283. Dialysis of Gastric Digestion. Make a dialyzer by firmly 
tying with a thread a piece of fresh, thin sausage skin over 
the mouth of a large bottomless test tube. Half fill this with 
the liquid product of an artificial digestion, containing 
digested and undigested albumin in solution. Immerse the 
dialyzer in a beaker of water. After some hours confirm the 
following reactions : 
Test Employed. 
Contents of Beaker. 
Contents of Dialyzer. 
Heat 
266 
Not coagulated. 
Coagulated. 
Biuret 
258 
Pink. 
Violet. 
Ferrocyanide . . . 
Millon’s 
261 
Not precipitated. 
Precipitated. 
259 
Precipitated. 
Precipitated. 
284. Preparation of an Active Pepsin Solution. Open the 
fresh stomach of a pig and very gently sponge it off. With 
a sharp knife scrape off the mucous membrane, containing 
the peptic glands. Put this, finely minced, in a beaker and 
cover with five times its volume of water, acidulated so as to 
contain o. 1-0.2% of HC1. Keep it at a temperature of about 
40° C, and after a few hours nearly all will have disappeared. PHYSIOLOGICAL CHEMISTRY. 
131 
Filter and preserve. The solution will possess active proteo- 
lytic properties, and keep well. 
The liquid might be subjected to dialysis to remove most 
of the peptones, then the enzyme with some proteid matter 
precipitated by absolute alcohol, dried and preserved as 
“ pepsin.” 
285. Artificial Gastric Digestion. Into a dialyzer, prepared 
as in 283, put some fresh, well-washed fibrin clots or finely 
diced white of a hard-boiled egg. Acidulate a beaker of 
water so that it may contain o. 1-0.3 °Jc of HC1. Add some 
of this solution to the dialyzer, and immerse it in the beaker 
of acidulated water. Drop a little pepsin or some of an 
active proteolytic extract of a pig’s stomach into the dia- 
lyzer. Keep the whole at a temperature of about 40° C, and 
agitate as frequently as is convenient. Note how the fibrin 
swells before solution. After some hours, test the contents 
of the beaker for peptones by the Biuret and Millon’s reac- 
tions. Note the bitter taste of the solution always present 
with peptones. 
286. The Action of Rennin. Carefully neutralize a little of 
the active extract of the pig’s stomach, and add it to a test 
tube of warm milk. If rennin is present, milk is coagulated 
in a few minutes. 
Or, soak a piece of cat’s stomach or true rennet, calf’s 
stomach, in dilute HC1, or in a strong solution of salt, for 
10 minutes. Exactly neutralize the solution, if necessary, 
with NaOH, and add it to warm milk. The solution soon 
coagulates. 
CHEMICAL EXAMINATION OF THE GASTRIC JUICE. 
287. Collection of the Juice by Ewald’s Test Breakfast. When 
the stomach is empty, administer a roll weighing about 132 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
35 g* (54° grains), with about 300 c.c. (10 fg) of warm 
water or tea without sugar or milk. After one hour, remove 
the remnants of the meal by the use of the stomach tube. 
About 40 c.c. (11 f~) should be obtained. A variation of 
20 c.c. either way would be pathological. 
288. Detection of Free Acids. Add a few drops of gastric 
juice to a dilute yellowish red solution of tropceolin. If free 
acids are present, even in as small a proportion as 1-4,000, 
the color instantly changes to reddish brown. Acid salts 
turn the solution yellow. Congo red may be used likewise. 
If free acids exist, even in as small a proportion as 1-50,000, 
the red color of the solution instantly turns sky blue. Both 
organic and inorganic acids affect these reagents. 
289. Estimation of Total Acidity. 10 c.c. of clear filtered 
juice, diluted with about 30 c.c. of water, are placed in a 
beaker, a few drops of neutral phenol-phthalein added, and 
the whole titrated with NaOH from a burette. The alkali 
is added drop by drop, with constant stirring, until a faint 
pink becomes permanent. This usually requires about 5 c.c. 
of alkali. The number of c.c. used, multiplied by .0364= % 
of acid, were all the acid HC1. 
290. Estimation of Free Acids. 10 c.c. of clear filtered 
juice is diluted with 30 c.c. of water, treated with 1 g. of pure 
CaC03 (precipitated chalk), which is neutral itself and neu- 
tralizes free acids but not acid salts. When effervescence 
ceases, the whole is titrated with NaOH, as above. The 
amount of alkali used measures the acid salts. The differ- 
ence between this and the previous determination represents 
the free acids. 
291. Gunzburg’s Color Test for Free HC1. A few drops of 
gastric juice are placed in a clean white evaporating dish and PHYSIOLOGICAL CHEMISTRY. 
133 
gently heated. A glass rod is dipped in Giinzburg’s reagent1, 
and drawn through the hot juice. A deep scarlet line is pro- 
duced, if even 1 in 20,000 parts of free HC1 is present. 
Phloro-glucin-vanillin does not react with organic acids or 
normal amounts of acid salts. 
292. Uffelman’s Test for Lactic Acid. Mix 6 drops of dilute 
FeCl3 with 2 drops of carbolic acid, and add water until 
this test solution is a delicate amethyst blue. Take some of 
this in a test tube and add a few drops of gastric juice. If 
lactic acid is present, even in the proportion of 1-2,000 
parts, the color instantly becomes yellow. By this test pure 
gastric juice is proved to contain no lactic acid. Whenever 
present it is set free from the food. 
293. Rapidity of the Stomach’s Absorption. Administer a 
capsule containing 0.1 g. (1.5 gr.) of KI. It will normally 
appear in the saliva in 10 to 15 minutes. To detect it, touch 
the tongue every few moments to a slip of starch iodide 
paper, 57-Note 1, and moisten the spot with a drop of dilute, 
yellow HN03. A blue coloration shows I. Note the time. 
294. Ewald’s Test of the Stomach’s Motility. Administer in 
a capsule i g. (15 gr.) of salol (phenol salicylate). It is not 
decomposed until it reaches the alkaline contents of the 
duodenum. It can be detected normally in about 70 min- 
utes. Urine is voided at short intervals. Paper is moistened 
in it and touched with a drop of 10% FeCl3 solution. The 
edge of the drop assumes a violet color if a trace of salicylic 
acid is present. 
Note i. Giinzburg’s solution is made by dissolving in 30 c.c. of absolute alcohol 2 g. 
of phloroglucin and 1 g. of vanillin. The solution is light yellow, with the odor of 
vanilla. LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
134 
1. How many important uses has HC1 in the gastric secretion? 
2. How could syntonin be tested for in exercise 285 ? 
3. Will the active extract of the pyloric end of a pig’s stomach digest 
starch in acid solution? Try it, if possible. 
4. Is the stomach ever alkaline, and why ? 
5. Why does the living stomach not digest itself? 
6. Does the acidity of the stomach aid in dialysis ? 
7. What is the zymogen theory of enzymes ? 
8. State the theory of the formation of HC1 in the stomach? 
9. What can be said of the comparative sizes or shapes of the 
albumin and peptone molecules, as deduced from their diffusibility ? 
10. State the probable nature of the change when proteids are broken 
down into albumoses and then to peptones. 
11. Why is rennet usually soaked in acid or salt solution? 
12. Will gastric juice digest raw white of egg as quickly as cooked? 
Why? 
13. State how the gastric juice assists in the digestion of fats. 
14. How does the gastric juice aid in the digestion of sugar? 
LABORATORY QUESTIONS. 
PANCREATIC JUICE. 
295. Preparation of a Solution of Pancreatic Enzymes. Clean 
a portion of a pig’s pancreas as free as possible from fat. 
Cut it up fine, and crush it in a mortar with pieces of glass. 
Cover this comminuted material with five or ten times its 
volume of saturated salt solution. After several days filter 
off the active extract. This will contain all the pancreatic 
enzymes except the fat-splitting enzyme. If it is desired to 
keep the solution, glycerine should be used as a solvent, 
or a little alcohol added to the salt extract. 
296. Action of Trypsin. Place in a dialyzer, 283, a coagu- 
lum of fibrin. Prepare a beaker of water containing 1% 
of Na2C03. In the dialyzer put a solution of pancreatin 
or pancreatic extract, prepared as above. Fill the dia- PHYSIOLOGICAL CHEMISTRY. 
135 
lyzer wdth the alkaline solution from the beaker, and set 
the whole in the beaker containing the remainder of the 
alkaline liquid. Keep the solution at a temperature of about 
40° C, and stir occasionally. The fibrin will gradually dis- 
appear without the swelling observed in gastric juice. 
297. Action of Rennin. Fill a test tube half full of sweet 
milk. Add 5 c.c. of pancreatic extract. Place the whole in 
abeaker of water, and warm to 40° C. In a few moments 
the milk will coagulate. Later the coagulum dissolves, di- 
ested by the trypsin. Confirm the following conclusions : 
(1) The solution has the bitter peptone taste. 
(2) The casein no longer curdles on boiling or on addi- 
tion of HN03. 
(3) The Biuret test yields a rose-red color. 
298. Action of Amylopsin. Fill two test tubes half full of 
dilute starch paste. Add a little pancreatic extract to each. 
Render one slightly alkaline with Na2C03, the other acid 
with HC1. Warm to the usual temperature. After 5 min- 
utes test each for glucose by Fehling’s test. The alkaline 
solution proves active. The acid solution is inactive. 
299. Action of the Fat-Splitting Enzyme. Dissolve a little 
butter in 5 c.c. of ether. Add a few drops of violet litmus 
solution. Beside it set a blank test of similarly colored 
water. The reaction of the butter solution must be exactly 
neutral, or made so, and the color a faint violet. Soak a 
small piece of fresh pancreas for xo minutes in strong alco- 
hol, and tease it up well. Remove it. Dry it with a filter 
paper, and immerse it quickly in the ether solution. After 
some minutes the litmus shows a decided red tinge. The 
solution has become acid by the liberation of butyric acid 
by the enzyme. 136 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
x. If fresh juice from a pancreatic fistula is at hand, determine the 
reaction, color, taste, effervescence with acids, emulsive power with 
fats, especially acid fats, and the coagulation of the drops of juice when 
poured into water. 
2. How do the products of gastric and pancreatic digestion differ? 
3. Are the final products of gastric or pancreatic digestion best 
suited to enter the blood ? Does Nature sustain your conclusion ? 
4. Will the pancreas digest itself, as did the stomach in 284? Try 
it, if possible. 
5. Which keeps best, a solution of gastric or of pancreatic digestion ? 
Why? 
6. Write the reaction when butter is split by an enzyme. 
7. Which shows the rennet action more strongly, gastric or pan- 
creatic extract? 
8. Are physiologists agreed as to the presence of rennin in the 
pancreatic fluid? 
9. Will a piece of the small intestine curdle milk ? 
10. Judged by your experiments, which has the greater amylolytic 
power, pancreatic extract or saliva? 
11. How does the digestion of fibrin differ in acid and alkaline 
digestive fluids ? 
LABORATORY QUESTIONS. 
300. Properties of Bile. Notice the reddish yellow color of 
fresh bile. That of herbivora is usually a greenish yellow. 
Note its bitter taste, due to bile acids, and its feeble alkaline 
reaction when diluted. Test its power of emulsifying fats? 
b)' shaking with a few drops of oil. 
BILE. 
30i. Separation of Cholesterin. The presence of cholesterin 
in bile is best shown from biliary concretions or gall stones. 
If these are colored, powder one, boil with water several 
times until the color is removed and the water decants clear. 
Next boil the clean powder for some minutes with a little 
alcohol. Set aside for a moment. When settled, decant PHYSIOLOGICAL CHEMISTRY. 
137 
some of the clear alcoholic solution on two clean glass mi- 
croscope slides. Warm these gently, and set aside. When 
dry, examine with the microscope for the characteristic large, 
flat, clear crystals of cholesterin. One specimen will turn 
red when touched with a drop of H2S04, the other blue 
with a mixture of H2S04 and tincture of iodine. 
302. Gmelin’s Test for Bile Pigments. 
(1.) Put an inch of clear HN03 in a test tube. Add one 
tiny crystal of cane sugar, warm, and the acid becomes light 
yellow, due to the presence of a little nitrous acid. When 
cold, gently let a few drops of dilute bile from a pipette 
flow upon the surface of the acid. At the juncture of the 
liquids there will appear colored rings, first green, then 
blue, violet and red, passing down the acid. Indican will 
yield only red and violet rings. Lutein yields only green 
and blue. Occasionally bile does not immediately yield these 
colors. 
(2) Mix a solution of bile with a strong solution of 
KN03. Let a few c. c.’s of concentrated H2S04 flow down 
the side of the inclined test tube and underlay the solution 
without mixing with it. The characteristic bile colors, as 
above, appear at the junction of the liquids. 
303. Pettenkofer’s Test for Bile Acids. Take half an inch 
of clear diluted bile in a test tube. Add just 5 drops of a 
10% cane sugar solution. Next add H2S04, drop by drop, 
cooling the tube thoroughly after the addition of each drop, 
until nearly an equal quantity of H2S04 has been added. 
If the tube becomes warm, the sugar becomes slightly car- 
bonized and the test ruined. If bile acids are present, the 
fluid becomes first opalescent, then clear, and successively a 
cherry red, carmine-red and purple-violet. Sometimes 138 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
these colors require several minutes to appear. Albumin, 
amyl alcohol, fatty acids, morphine, phenol compounds, 
etc., give this reaction, so that it cannot be applied to 
complex organic mixtures without tedious preparation and 
precaution. 
304. Spectroscopical Examination of Bile. Set a thin, flat 
bottle filled with a clear, dilute solution of bile before the 
slit of the spectroscope. Examine the absorption spectrum 
produced, with the black bands at each side, obscuring all 
but the red and yellow colors. Fix the exact point of ter- 
mination of these bands by means of the scale in the in- 
strument. They will be found to differ somewhat, according 
to the dilution of the bile. Place before the slit any other 
similarly colored solutions not containing bile, and notice 
that they do not produce the same characteristic absorption 
bands. 
Concerning the adjustment of the instrument, consult 
the demonstrator. 
LABORATORY QUESTIONS. 
1. What salt in human bile does Pettenkofer’s test principally detect? 
2. Do the various colors in Gmelin’s reaction probably correspond 
to definite oxidation products? If possible, examine a changing 
Gmelin’s reaction by placing the test tube before the spectroscope slit. 
3. Try Pettenkofer’s test with urine containing bile. What is the 
result? 
4. Does bile contain iron? Evaporate and ignite some. Dissolve 
in dilute hot HNOs, dilute and filter. Touch the solution with a drop 
of KCyS. A red color indicates iron. 
5. What are the bile coloring matters and the theory of their origin? 
6. Will pig’s bile digest raw starch ? If possible, try it. 
7. Will bile dissolve insoluble soaps? Make a calcium soap, 233-1, 
and confirm it, if there is time. 
8. Will bile precipitate solutions of peptones, pepsin, acid albumin, 
etc. ? 
9. Will bile reduce cooked starch to sugar? Try it. PHYSIOLOGICAL CHEMISTRY. 
139 
305. Preparation of Fibrin. Stir some freshly-drawn blood 
with a stirring rod, or better, a bundle of wires, until the 
fibrin is all deposited around the rod or wires. Wash this in 
water until white, and prove it a proteid by the Xanthoproteic 
reaction, 257. 
BLOOD. 
306. Microscopical Appearance of Blood. Place a drop of the 
defibrinated blood on a microscope slide, cover it with a 
cover glass, and examine with the high power of the 
microscope. Detect the red and white corpuscles. Compare 
the appearance of human blood with that of the dog, cow, 
bird, fish, etc., by examining the slides prepared. 
307. The Odor of Blood. Take some of the defibrinated 
blood in a test tube. Add a few drops of H2S04. Stir up 
the solution, and note the peculiar odor of blood, intensified 
by the liberation of traces of volatile acids by the H2SQ4. 
308. Preparation of Reduced Haemoglobin. Make a reducing 
solution as follows : In a test tube put a strong solution of 
SnCl2, add a little powdered tartaric acid, then NH4OH until 
the solution is quite clear and alkaline. This solution will 
absorb oxygen. Shake in a test tube some blood with a few 
c.c.’s of this reducing solution. The color changes to the 
dark purplish red of reduced haemoglobin. Keep agitating 
the blood in the presence of air, and it gradually resumes 
the bright red color of oxyhaemoglobin. 
309. Tests for Serum Albumin. Pour some serum from a 
large blood clot. Dilute it with 10 times its volume of 
water, and use the solution in the following tests: 
(1) The Ferrocyanide Test (343). Keep diluting a small 
amount of serum albumin successively with 9 times its vol- 140 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
ume of water, thus making a a etc., solution. Test 
each time, and determine the limit of delicacy. 
(2) The Heat and Acid Test (341). 
(3) Heller's Nitric Acid Test (342). Keep diluting the 
serum albumin, as above, until the limit of detection is 
reached. Compare the delicacy of this with the K4FeC}r6 
test. 
310. Preparation and Detection of Paraglobulin (Fibrinoplas- 
tin, or serum globulin). Pass C02, 120, through a beaker 
of dilute serum for 20 minutes or more. Let the ppt. settle. 
It is paraglobulin. Decant and, after washing with water, 
dissolve some of it in a little dilute salt solution. Test it 
by the Biuret test, 358, and prove it a proteid. 
311. Detection of Fat in Blood. In a large test tube shake 
equal quantities of blood serum and gasoline, which sub- 
stance will dissolve fat. Let the gasoline rise, and pour it 
into a watch glass or evaporating dish. When evaporated, 
examine for globules of fat. 
312. Detection of Some Salts of the Blood. Evaporate some 
blood to dryness in an evaporating dish. Raise the tem- 
perature to a red heat. When cool, add a little HN03, 
heat, dilute and filter. Test some of the solution as 
follows : 
1. Add KCyS. A red color indicates iron. 
2. Add (NH4)2Mo04, and boil. Yellow ppt. on standing 
indicates phosphates. 
3. Add AgNOg. A white cloud indicates chlorides. 
313* The Guiacum Test for Blood. Moisten any dry blood 
stain and press it against a piece of blotting or filter paper. 
A faint reddish impression is taken on the paper. Touch 
this with a drop of a fresh tincture of guiacum, and then PHYSIOLOGICAL CHEMISTRY. 
141 
with one drop of hydrogen dioxide, or, better, ‘‘ozonized 
ether.”1 A blue color rapidly appears. Saliva, protoplasm, 
semen, milk, etc., give this reaction, but in practice blood 
is the only red stain which yields it, except fruit stains, 
which turn blue with ammonia. Red wine stains give this 
reaction only after standing some hours. The test is valu- 
able in connection with other facts. 
314. The Haemin Test for Blood Stains. Cut out a dry blood 
stain from a piece of cloth, no matter how old the stain. 
Place it on a glass microscope slide. Add exactly 3 crystals 
of NaCl and 2 drops of glacial acetic acid. Heat gently 
until it boils, then squeeze the acid from the cloth. Gently 
evaporate the liquid. When dry, examine the slide, under 
the high power of the microscope, for the small, dark red 
bundles, rods or prismatic crystals of hydrochlorate of 
haemin. They must not be mistaken for the large, trans- 
parent crystals of NaCl. In case they do not appear, repeat 
the process with the same stain until expert. Only blood 
will yield this test. 
315. The Spectroscopic Examination of Blood. Place before 
the slit of the spectroscope a thin, flat bottle filled with clear 
blood, diluted with water so that the blood forms only about 
of 1 per cent. Examine the absorption spectrum, noting 
the black bands on either side and the two black bands in the 
center. Fix the position of all these by means of the scale 
in the instrument. The exact extent of these bands depends 
upon the dilution of the blood. Now place before the slit, 
dilute solutions of fuchsin, cochineal, etc., prepared by the 
Note i. Ozonized ether is prepared by shaking some ether with H2O2, hydrogen 
dioxide, and decanting the ether, which contains the real hydrogen dioxide, yielding 
nascent oxygen. 142 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
demonstrator. Note their spectra, and with what ease blood 
can be detected. 
Consult the demonstrator in adjusting the instrument, and 
if time is given, by means of the comparison prism, compare 
the spectra of reduced haemoglobin, oxyhaemoglobin and 
carbonic oxide haemoglobin. 
316. Estimation of the Number of Blood Corpuscles by the 
Haematocrit. Thoroughly cleanse the finger. Prick it near 
the nail with a sharp needle. Reject the first drop. Suck 
the second drop into the small graduated capillary tube by 
means of the little rubber bulb. When the capillary tube is 
evenly filled with blood, place it, O0 mark out, in the frame 
and rotate it rapidly for 1 minute. The blood does not 
coagulate, and the heavy red blood corpuscles gravitate to 
the distal end of the tube. Next are arranged the white 
blood corpuscles, and last the clear liquor sanguinis. Each 
10 divisions on the tube occupied by the red blood corpuscles 
correspond approximately to a million red corpuscles per 
cubic millimetre. Five million corpuscles per cubic milli- 
metre is normal. 
LABORATORY QUESTIONS. 
1. Which of the three tests for serum albumin was most delicate? 
2. Can you invent a method that will detect the alkalinity of freshly 
drawn blood ? 
3. To which of the salts detected in the blood will its alkalinity prob- 
ably be due? 
4. Is the coagulation of blood a chemical change? 
5. State the part played in the phenomena of coagulation by fibrin- 
ogen, paraglobulin and fibrin ferment. 
6. Can the approximate age of blood stains be determined by their 
comparative solubility? Soak in 5 c.c. of cold water a dry blood stain 
a few days old, one month old, and two months old. What do you con- 
clude ? 
7. How may the color of cochineal dissolved with alum be distin- 
guished by the spectroscope from a similarly colored blood solution ? PHYSIOLOGICAL CHEMISTRY. 
143 
MILK. 
317. Determination of the Reaction. Note that fresh milk 
often has a faint alkaline reaction to litmus paper, and sour 
milk always an acid reaction, due to free lactic acid. Fresh 
human milk is more alkaline than cow’s milk, which may 
often be neutral or even acid. 
318. Microscopical Examination of Milk. Place a drop of milk 
on a microscope slide. Cover it with a cover glass, and 
examine the fine emulsion of fat globules. 
319. Detection of Lactalbumin. Boil some milk in a beaker. 
No casein is precipitated, but a scum of coagulated lactalbu- 
min forms on the surface. Skim this off. Wash it, and prove 
it a proteid by the Xanthoproteic reaction, 257. 
320. Separation of Casein. Put some sweet milk in a beaker. 
Add a little acetic acid, and warm gently. The casein is 
precipitated. Filter off the whey, and set aside for the next 
test. Test the casein, and prove it a proteid by 257. 
321. Detection of Lactose. Test the whey formed in 320 for 
lactose by Fehling’s test. 
322. Detection of Fats. Fill a test tube one-third full of 
milk. Add 5 c.c. of KOH and a little gasoline. Set 
the mixture aside and shake frequently. After a few minutes 
decant, evaporate the gasoline and examine the butter 
remaining. Butter cannot be dissolved from cow’s milk by 
gasoline or ether without breaking up the emulsive envelope 
by agitation like churning or alkalies like KOH. Human 
milk yields its fat directly to ether. 
323. Detection of Some Salts in Milk. Evaporate some whey 
in a porcelain evaporating dish. When nearly dry, heat 
slowly, to avoid spattering. When dry, raise the heat to red- 144 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
ness for a minute, to destroy the organic matter. Cool, and 
add 5 drops of HN03. Heat gently, dilute with 5 c.c. of 
water, filter, and test portions as follows : 
(1) Add (NH4)2Mo04, and heat. Yellow ppt. indicates 
phosphates. 
(2) Add AgNOg. A slight turbidity indicates chlorides. 
(3) Add BaCl2. A faint cloud indicates sulphates. 
324. Determination of the Specific Gravity. Fill the cylindri- 
cal graduate two-thirds full of unskimmed milk. Insert the 
hydrometer, and take the specific gravity. Remove this 
instrument, and repeat the determination with the New York 
Board of Health lactometer. Note that this instrument is 
so constructed that ioo° represents a specific gravity of 1.029, 
below which unadulterated milk is supposed never to fall. 
The laws of New York require milk to have a density of 
not less than 1.029, and total solids of not less than 12 per 
cent, of which 3 per cent must be fats. 
LABORATORY QUESTIONS. 
1. To what cause is the slight alkalinity of milk due? 
2. How would boiling affect lactalbumin, globulin and casein pres- 
ent in milk? 
3. Acidulate some boiled and some fresh milk, and see if there is 
evidence that heat has produced a change. 
4. How does pasteurized milk differ from boiled or sterilized milk ? 
5. By the use of rennet or pepsin, how may the so-called sweet pepsin 
curds for invalids be prepared ? 
6. Why is lime water often given with milk ? 
7. How would the addition of water affect the density of milk ? The 
addition of cream? 
8. How might the analysis for per cent of total fats and solids be con- 
ducted, did time allow? See 322 and 181. 
9. How does churning affect milk ? LABORATORY EXERCISES 
IN 
URINALYSIS URINE. 
147 
URINE. 
APPROXIMATE NORMAL URINARY CONSTITUENTS. 
(In 24 hours.) 
Water 
1500. grams, 
51 A- 
ounces. 
Urea. 
33-i8 “ 
500 grains. 
Uric acid 
•55 “ 
8 
Hippuric acid 
•44 “ 
6 
< < 
Creatinin. 
.91 “ 
14 
{< 
Pigments and other organic matter . . 
10. 
154 
t i 
Chlorides of Potassium, Sodium and 
Ammonium 
13- 
200 
( ( 
Sulphates of Sodium and Potassium . 
2.20 “ 
33 
(( 
Phosphates of Sodium and Potassium 
3- 
45 
( ( 
Phosphates of Calcium and Magnesium 
1.20 “ 
18 
( ( 
EXAMINATION OF NORMAL URINE. 
Color. 
Urine tints vary from pale yellow to brownish black. The amount of 
coloring matter is measured by Vogel’s scale. Urine is pale yellow after 
free potations or polyuria from any cause. High-colored urines are in- 
duced by pyrexia or abstinence from liquids; orange-red from the 
presence of santonin in alkaline urine ; reddish to brown from blood ; 
brown to black from melonotic cancer or the administration of senna, 
tannic or carbolic acid, resorcin, naphthalin, etc.; greenish from bile 
coloring matter. 
Odor. 
The characteristic urine odor becomes ammoniacal and offensive on 
standing. Medicinal agents often impart characteristic odors, as aspara- 
gus, cubebs, copaiba, garlic, tolu, etc. Turpentine gives a violet odor. 
The reaction of mixed urine for 24 hours is normally acid, from the 
presence of acid sodium phosphate, NaH2P04. Occasionally urine gives 
Reaction. 148 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
an amphoteric reaction, changing both litmus colors, due to the presence 
of acid and alkali salts. Urine may be alkaline after a meal or from ad- 
ministration of alkaline salts, organic acids, etc. 
325. Detection of Fixed and Volatile Alkalies. Dip slips of 
red litmus paper in samples of urine A and B. Both are 
turned blue. Lay them away to dry. A remains blue and 
B resumes its former red color. A is alkaline from fixed 
alkali, Na or K, while B is alkaline from volatile alkali, 
ammonia. 
326. Observation of Urine Changes. Take a sample of fresh 
urine and place it in a warm place, where it can be examined 
daily. Test it frequently by litmus paper. Note that it is 
acid, and that its acidity increases for a few hours, due to 
acid fermentation, in which mucus acts as a ferment. The 
acidity then declines, and the urine becomes at last alkaline, 
from alkaline fermentation, caused by the propagation of 
fission fungi. The odor becomes ammoniacal as the fungi 
transform urea into ammonium carbonate. 
Reaction—C0(NH2)2+2H20=(NH4)2C03. 
Urea Ammonium Carbonate 
SPECIFIC GRAVITY. 
The normal specific gravity is about 1.020, or, as often written 1020, 
when taken at 150 C. or 6o° F. A decrease in the normal quantity of 
urine increases its density; an increase in quantity lowers its density. 
When albumin is present, as in organic albuminuria, or Bright’s disease, 
the density is abnormally low, while in the presence of sugar, as in 
diabetes mellitus, it is abnormally high. 
327. Correction of a Urinometer. Fill a urinometer jar with 
distilled water at 150 C.(6o° F.). In this immerse the urin- 
ometer, avoiding contact with the sides of the jar. Read the 
division on the scale that corresponds with the surface, look- 
ing above the miniscus or below, as is found most correct for URINE. 
149 
the zero reading. Always adhere to this method of reading 
when using the same urinometer. The urinometer may be 
several degrees out of the way. If so, note the amount of the 
variation, and always add or subtract this correction, as the 
case may be, when taking the specific gravity with the instru- 
ment. Many otherwise good urinometers are several degrees 
at fault. A new instrument should never be brought into 
use before thus testing its accuracy. 
If the urine is warmer than i5°C., add i° to the density 
for every 40 of extra C. temperature, or for every 70 of extra 
F. temperature. 
TOTAL SOLIDS. 
The total solids in urine do not largely vary during health, notwith- 
standing wide variation in the volume of urine. Solids average 67 
grams, or about 1,000 grains, in 24 hours. The total solids are accurately 
determined by evaporating a measured quantity of urine and weighing 
the residue, 181. The total solids are determined with sufficient accu- 
racy for clinical purposes from the specific gravity, when the total quan- 
tity of urine is known, by the use of Haser’s coefficient, 2.33. 
328. Determination of Total Solids. Determine the specific 
gravity of sample C. If the total volume for 24 hours was 
1,500 c.c. (51 fl. g), determine the total solids by the follow- 
ing formula : 
sP. g. Xvoiume __ solids in grams. 
UREA. 
Urea, CO(NH2)2, forms colorless crystals, odorless, bitter, soluble in 
water, and acting as either a weak acid or a base. The mean amount in 
24 hours’ urine is 33 grams, or 512 grains. 
329. Preparation of Urea Nitrate. Evaporate a specimen of 
urine, under the hood, to a syrupy consistency. Cool, and 
add some pure concentrated HN03, keeping the mixture per- LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
150 
fectly cool all the time. Cool with ice, if possible, and in a 
short time rhombic plates of urea nitrate will separate. Urea 
may easily be obtained from this salt. See any text. 
330. The Hypobromite Quantitative Estimation of Urea. Put 
about 20 c.c. of NaOH in a beaker. Stir, and add bromine, 
drop by drop, until the solution is orange-yellow. Fill the 
Doremus ureameter with this solution. Fill the 1 c.c. 
pipette with urine, and carefully introduce the urine into the 
long arm of the instrument, taking care to avoid the intro- 
duction of air. Decomposition immediately takes place, 
with the production of nitrogen. After 15 minutes the action 
is complete. Read off the volume of nitrogen on the grad- 
uated scale. The reading gives the weight of urea in 1 c.c. 
of urine. The total quantity of urea in 24 hours is determined 
by multiplying this reading by the volume of urine expressed 
in c.c., or if the decimal point be moved two places to the 
right, the instrument reads the per cent of urea. Normal 
urine contains about 0.02 gram per c.c., or 2%. 
Reaction— CO(NH2)2-f-3NaBrO=C02+3NaBr-J-2H20-l-2N. 
Uric acid, H2(C5H2N403'), is insoluble in water. It presents the ap- 
pearance of red sand. Its neutral salts are soluble in water, but its acid 
salts only feebly so. For this reason acid urates often ppt. when urine 
cools. Strong acid, added to a urine highly charged with urates, fre- 
quently precipitates uric acid or acid urates in the form of a cloud, that 
may be mistaken for albumin. Uric acid crystallizes, and may be 
detected microscopically by its prismatic or whetstone-shaped crystals of 
a yellowish red color. The normal excretion is about 0.55 grams, or 
8 grains, in 24 hours. This quantity is diminished in gout, etc. 
URIC ACID. 
33i- Separation of Uric Acid. Take ioo c. c. of dense urine 
in a test tube. Add io c.c. of strong HC1. After two days, URINE. 
151 
decant the liquid from the fine red crystals in the bottom of 
the tube. Examine these crystals under the microscope. 
332. The Murexid Test for Urates. To a little highly colored 
urine, add a few drops of cold, strong HN03, and evaporate 
to dryness at a gentle heat. Touch the yellow residue with 
a drop of NH4OH. A crimson purple indicates urates. 
This color is due to the production of purpurate of ammonia or mu- 
rexid, a substance which the ancients obtained from shell fish (murex), 
and used as the royal purple dye. 
CHLORIDES. 
The chlorides are those of sodium, potassium and ammonium. The 
mean daily discharge is about 13 grams, or 200 grains, or about 0.5-1%. 
The amount is diminished in fever. Chlorides may entirely disappear in 
severe cases of pneumonia. Their reappearance is the first indication of 
improvement. 
333. Detection of Chlorides. Render a test tube of urine 
acid with a few drops of HN03. Add a strong solution of 
AgN03(i3 to 1 drop by drop. If the white ppt. sinks in 
curdy drops without diffusing, the chlorides are undiminished. 
If diffusion occurs, chlorides are diminished to about o. i per 
cent. Should no ppt. occur, chlorides are absent. 
334. Mohr’s Quantitative Estimation of Chlorides. Titrate 
10 c.c. of urine, diluted with water, with a standard solution 
of AgN031, using K2Cr04 as an indicator, according to the 
method 186. From the results calculate the per cent of 
chlorides. 
This method is not quite accurate. Highly colored urines must be 
diluted to a pale color. 1 c.c. of AgNC>3 is usually allowed for small 
quantities of interfering substances. The method is more accurate when 
the 10 c.c. of urine are carefully evaporated, ignited with a little NaN03, 
Note i. This is prepared by dissolving 29.075 grams of AgNC>3 in 1,000 c.c. ofwater. 
1 c.c. of this solution will unite with exactly 0.01 gram of NaCl. 152 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
cooled, diluted, neutralized and titrated as above. The most accurate 
methods are too complicated for use by physicians. 
335. Centrifuge Quantitative Estimation of Chlorides. The 
centrifuge tube is filled to the 10 c.c. mark with filtered urine, 
acidulated with 2 drops of HN03, and a strong solution of 
AgN03 poured in up to the 15 c.c. mark. The whole is 
evenly rotated1 for exactly three minutes, or until the precipi- 
tated chlorides are completely packed. The volume of the 
precipitate is read off. Every c.c. represents 1% of 
chlorides by bulk. Normal chloride precipitates range from 
10-12 % bulk measure. 
PHOSPHATES. 
Two distinct classes of phosphates exist in the urine: (1) Alkali 
phosphates of sodium, potassium and ammonium, soluble in water ; 
(2) Earthy phosphates of calcium and magnesium, nearly insoluble in 
water but soluble in acids. Hence when urine is made alkaline, earthy 
phosphates precipitate, and when urine undergoes the ammoniacal putre- 
factive change, earthy phosphates are changed to triple phosphates thus : 
2MgHP04+(NH4)2C03=H2C03+2MgNH4P04, or triple phosphate. 
336. Detection of Earthy Phosphates. Render a test tube of 
urine alkaline with NaOH. Heat, and the earthy phosphates 
are precipitated. Filter the solution, and save the clear 
filtrate for use in the next experiment. 
337. Detection of Alkaline Phosphates. To the clear filtrate 
from the last experiment, add one-third its volume of mag- 
nesium mixture2. Alkali phosphates are precipitated in the 
form of magnesium ammonium phosphate. Examine these 
Note i. The centrifuge should be kept well oiled. The arms should be balanced by 
tubes containing equal quantities of liquids. The machine should not be stopped sud- 
denly nor rotated to excessive speed. 
Note 2. Magnesium mixture is composed of MgSC>4 and NH4CI, each 1 part, dis- 
tilled water 8 parts, and strong NH4OH 1 part. URINE. 
153 
crystals of triple phosphate under the microscope. They 
will appear in the form of leaves and so-called “coffin lid” 
crystals, the latter more abundant on standing. These are 
always present in the microscopical deposit in ammoniacal 
urine. 
338. Centrifuge Quantitative Estimation of Phosphates. Fill 
the centrifuge percentage tube to the 10 c.c. mark with urine. 
Add 5 c.c. of magnesium mixture. Both earthy and alkali 
phosphates are precipitated. Rotate the tube for three min- 
utes and read the percentage. Every c.c. represents i°/0 
of phosphates by bulk. Normal urine yields 8% by vol- 
ume of phosphate precipitates. 
The urine contains sulphates of sodium and potassium, in all about 2.2 
grams, or 33 grains, in 24 hours. Their determination is of little clinical 
value. 
SULPHATES. 
339. Detection of Sulphates. Render a test tube of urine 
slightly acid with HC1. Add an excess of BaCl2. If a 
simple turbidity results, sulphates are normal. If an opaque, 
cream-like precipitate appears, sulphates are excessive. If 
only a slight cloudiness is produced, sulphates are diminished. 
340. Centrifuge Quantitative Estimation of Sulphates. Fill the 
centrifuge percentage tube to the 10 c.c. mark with urine. 
Add 2 drops of HC1 and then BaCl2 solution up to the 15 c.c. 
mark. Rotate the tube three minutes. Read the per cent as 
usual, counting every c.c. of precipitated BaS04 equiva- 
lent to i°/0 of sulphates by bulk. A percentage of 0.8 is 
normal. 
1. On what principle is Vogel’s scale constructed? 
2. What is the color of urine containing bile? 
3. What is the normal reaction of urine, and to what is it due? 
LABORATORY QUESTIONS. 154 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
4. How do phosphates change in passing from the blood to the 
urine ? 
5. Why will the eating of acid fruits produce an alkaline urine ? 
6. Of what value is the detection of volatile alkali in urine ? 
7. Can you find a urine with amphoteric reaction ? 
8. How long was it before the urine in exercise 326 became alkaline? 
What effect would temperature have on this change? 
9. Ammonium carbonate is composed of two gases. Is it volatile ? 
10. What is the difference between specific gravity and density? 
11. What is a meniscus, and why so called? 
12. What would cause variations in the reading of a urinometer after 
its manufacture? 
13. When a urinometer reads 23, what does it mean ? 
14. State the formula for determining total solids in the form of a pro- 
portion ? 
15. How might urea be obtained from urea nitrate? 
16. In what form are proteids chiefly excreted ? 
17. Why might urea be called a compound ammonia ? 
18. Why is urea an ideal excretory product? 
19. What substance is formed when Br is added to NaOH ? Write 
the reaction. 
20. What is the advantage of knowing the amount of urea excreted ? 
21. Name some errors arising in the hypobromite method? 
22. How may urates complicate the test for albumin? 
23. Write the formula for an acid urate. 
24. Will uric acid yield the murexid test ? 
25. If time is given, determine the approximate amount of uric acid 
in urine by precipitating 200 c.c. of urine with 20 c.c. of HC1. Let it 
stand, decant, wash the crystals, weigh, and calculate the amount in the 
total twenty-four hours. 
26. Show how the amount of 334-Note 1, which it is necessary 
to make up to 1,000 c.c., can be calculated? 
27. Of what value is a centrifuge to a physician ? 
28. What is the value of the determination of chlorides? 
29. What are triple phosphates ? What is microcosmic salt ? 
30. What is the light, white ppt. that often forms in cold urine ? 
31. Write the formulas for two acid and one normal phosphate. Give 
the reaction of each salt to litmus paper. URINE. 
155 
32. What urinary deposit will dissolve on warming? 
33. A deposit dissolves in a few drops of acid. What is it? 
34. A deposit proves insoluble in acetic acid. What is it ? 
35. What other tests for phosphates might be used ? 
EXAMINATION OF ABNORMAL URINE. 
ALBUMIN. 
Among the proteids found in the urine are serum albumin, paraglob- 
ulin, mucin, peptone, albumoses, fibrin, haemoglobin, etc. The chief 
clinical interest centers in serum albumin. It may be present: (1) By 
degeneration of the renal structure; (2) By a change in the diffusi- 
bility of the blood; (3) By an increased blood pressure. The pres- 
ence of casts or distinctive renal epithelium is the only positive evi- 
dence of renal lesions. Urine containing albumin is usually of lowered 
specific gravity. The quantity of albumin may run as high as 30 grams, 
or 450 grains, but usually is not over 1-2% by weight. A suitable test 
for serum albumin ought not to react with any other of the above-named 
proteids, or even coloring matters or salts or medicinal substances pres- 
ent in the urine. 
341. Heat and Nitric Acid Test. Take half a test tube of al- 
buminous urine. If alkaline, render it neutral with a drop 
or two of acetic acid Bring the upper portion to boiling. 
Any cloudiness produced is due either to albumin or phos- 
phates. Now add 1 c. c. of strong HN03. Phosphates dis- 
solve. Turbidity due to albumin is intensified. 
A large amount of mucin from urinary passages will be mistaken by 
this test for albumin. When small amounts of albumin are present, ex- 
act neutralization is required to insure the detection of acid and alkali 
albumin. See 274 and 275. 
342. Heller’s Nitric Acid Test. Place a little clear, strong 
HNO;j in a test tube. With a pipette gently float an inch of 
albuminous urine on the acid surface without mixing. If al- 
bumin is present, an opalescent ring appears at the point of 
contact. With very minute quantities of albumin, the ring 
appears only after io or 15 minutes. 156 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
A cloud of amorphous urates sometimes appears, but higher up than 
the albumin ring, and disappears on gently heating, while the albumin- 
ous opalescence is intensified. Any mucin will appear, if at all, near the 
surface, as it is soluble in strong HNO3. This test is one of the most 
delicate and accurate known, when carefully and intelligently performed. 
343. The Ferrocyanide Test. Take half a test tube of clear 
urine. Mix with it about one-fifth its volume of fresh, strong 
potassium ferrocyanide solution. Now add 10-15 drops of 
acetic acid. If albumin is present, it will come to view as a 
white precipitate. 
This test precipitates normal acid and alkali albumin, does not act 
with urates, phosphates, alkaloids or peptones, and the addition of 
K4FeCy6 before the acid keeps mucin in solution. This is one of the 
most delicate and satisfactory tests. The many other tests for albumin 
are no better than the three given, and in general are inferior. 
344. Esbach’s Quantitative Test for Albumin. Fill an Esbach’s 
albuminometer up to the mark U with albuminous urine, 
then add the picric acid reagent1 to the mark R. Shake well, 
cork, and set aside for twenty-four hours. Read off the 
amount of precipitated albumin on the graduated scale which 
expresses parts per thousand or grams of dry albumin per 
liter. Move the decimal point one place to the right, and 
the reading expresses per cent of dry albumin. This method 
is approximate only. 
345. Centrifuge Quantitative Estimation of Albumin. Fill a 
centrifuge percentage tube to the io c.c. mark with urine. 
Add 3.5 c.c. of fresh, strong K4FeCy6 solution, and 1.5 c.c. 
of acetic acid. Mix thoroughly, and rotate the tube for 
three minutes. Read off the amount, and report 1% by vol- 
ume of albumin for each c.c. of precipitate. This is the 
most accurate method practically available. 
Note i. This picric acid reagent contains picric acid i part, citric acid 2 parts, and 
water 50 parts. URINE. 
157 
GLUCOSE. 
Dextrose, laevulose, lactose, etc., are all found in the urine. Dex- 
trose, also termed glucose, or grape sugar, is the sugar of most clinical 
interest. It exists in the blood normally in small amounts, and in the 
urine in only the most infinitesimal quantity. Temporary glycosuria is 
caused by fever, cholera, gout and diseases of the lungs, liver, spleen and 
brain, and by the administration of many toxic drugs. Persistent glyco- 
suria may be regarded as symptomatic of grave defect of either the brain, 
liver, or pancreas. It is the most constant symptom of diabetes melli- 
tus. The presence of sugar usually raises the specific gravity of the urine. 
The amount may vary from o to 1,000 grams, or o to 15,000 grains, in 
24 hours. 
346. Illustration of the Action of the Copper Tests. Take a 
test tube of CuS04 solution. Add KOH, and notice the 
blue insoluble ppt. of Cu(OH)2. Divide this among four 
test tubes. Leave No. 1 as it is. Into No. 2 put a few drops 
of a solution of glucose, in No. 3 a few drops of glycerine, 
and in No. 4 a pinch of potassium and sodium tartrate (Ro- 
chelle salt). Shake them all. No. 1 is unchanged. Nos. 
2, 3 and 4 dissolve to a clear blue solution. Boil them all. 
No. 1 throws down black CuO, No. 2 a yellow ppt., and Nos. 
3 and 4 show no change. Now add glucose to 3 and 4, boil, 
and both ppt. yellow Cu20. 
Sugar, glycerine, Rochelle salt, and many other organic compounds 
keep Cu(OH)2 in solution. On boiling, glucose and some related sugars, 
248, have the power of reducing Cu(OH)2 to yellowish red Cu20. This 
property is possessed by deteriorated Rochelle salt, and hence all tests 
using solutions of this salt become in time unreliable. 
347. Trommer’s Test for Glucose. Take half a test tube of 
urine. Add 2 drops of dilute CuS04. Next add a liberal 
quantity of KOH. If sugar is present in any quantity, the 
blue Cu(OH)2 first pptd. dissolves to a deep blue liquid, and 
when boiled ppts. reddish yellow Cu20. A precipitated yel- 
low powder is the only certain evidence of sugar. In case 158 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
the result seems negative, set aside to settle. If no yellow 
ppt. appears, glucose was absent. This test is much inferior 
to the one next described. 
348. Fehling’s Glycerine Test for Glucose. Prepare some 
glycerine Fehling’s solution thus: Take some CuS04 solu- 
tion in a large test tube. Add a liberal amount of KOH, and 
then glycerine until when shaken a clear, deep blue solution 
results1. 
Take half a test tube of this solution, boil, and add 5 
drops of urine containing glucose. Again raise it to boiling. 
A ppt. appears, gradually growing more yellow, and will 
settle to the bottom, in time, in the form of a reddish yellow’ 
powder. 
This is the best glucose test for physicians’ use. Albumin must be 
removed if present in any considerable quantity. If 5 drops of urine 
yield no ppt., add 5 drops more and boil again, continuing until urine 
equaling in volume the Fehling’s solution has been added. Do not add 
more, as normal urine contains substances which will reduce Fehling’s 
solution, if present in very large amount. A green or blue ppt. in the 
bottom of the tube is not sugar but precipitated earthy phosphates. 
349’ Bottger’s Bismuth Test for Glucose. First remove all 
albumin, if present, from some saccharine urine by acidulating 
the urine slightly, boiling and filtering. In a test tube put 
equal quantities of urine and KOH. Add a pinch of bismuth 
subnitrate. Boil, and if glucose is present, the white powder 
in the bottom of the tube becomes black from the reduction 
of metallic bismuth. Albumin and all sulphur compounds 
Note i. Fehling’s glycerine solution may be prepared for office use by the following 
formula : Dissolve 30 gr. of copper sulphate in ounce of distilled water, add % ounce 
of glycerine, mix thoroughly and add 5 ounces of liquor potassae. Preserve in a rubber 
stoppered bottle. It keeps indefinitely, and is much superior to Fehling’s solution made 
with Rochelle salt, as this salt, even when kept in a separate solution, deteriorates in a 
few months. URINE. 
159 
give the same result, so that this test is much inferior to the 
previous one. 
350. The Phenylhydrazine Test for Glucose. Take 25 c.c. of 
suspected urine. Add 1 gram of phenylhydrazine hydro- 
chloride (do not allow it to touch the hands), 0.75 gram of 
sodium acetate and 10 c.c. of distilled water. Keep the solu- 
tion nearly to the boiling point for an hour. Even minute 
quantities of sugar yield a yellow ppt., which under the 
microscope is seen to consist of fine, bright yellow needles of 
phenylglucosazone, arranged singly or in stars. 
This test is one of the most delicate and accurate known, but is too 
complicated for daily use. It is reliable in the presence of albumin and 
the products of decomposing urine. 
351. The Fermentation Quantitative Test for Glucose. Fill two 
receivers with suspected urine. Add a small piece of yeast 
to one, and set both aside for 24 hours. Filter, if necessary, 
and take the specific gravity of each. The number of degrees 
of density lost by the fermented urine represents grains of 
sugar in each fluid ounce. The percentage of sugar may be 
calculated by multiplying the degrees lost by 0.23. The 
results are only approximate, and the test is not trustworthy 
where the quantity of sugar is very small. 
352. Fehling’s Quantitative Test for Glucose. Take 35 c.c. of 
Fehling’s quantitative copper solution1 in a beaker. Add 
twice its volume of distilled water, and heat. Fill a burette 
with the urine to be examined. When the copper solution 
boils, slowly drop in the urine, constantly stirring, and boil- 
ing until the blue color entirely disappears, which can be 
best seen by looking through the solution onto a white wall 
Note i. The standard solution is prepared as follows: Pure copper sulphate, 4.742 
grams; potassium hydroxide, 23.50 grams; strong ammonia, 450 c.c.; glycerine, 38 c.c.; 
make up with distilled water to 1,000 c.c. This solution keeps perfectly. The color in 
35 c.c. of the solution will be exactly destroyed by 0.02 gram of glucose. 160 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
or piece of paper. Then read off the number of c.c. of 
urine used, which will contain exactly 0.02 gram of sugar. 
The per cent of sugar is computed thus : 
100 X 0*02 
s—, , . = per cent. 
No. of c.c. of urine * 
Thus, if the quantity used was 2 c.c.: 
= ! cj0 of glucose. 
This operation should be conducted as quickly as possible, as the 
oxygen of the air restores the blue color to the solution, hence the stu- 
dent need not be in a doubt as to the accuracy of the determination if the 
solution on standing is noticed to be blue. 
353. The Polariscope Quantitative Method. This method is 
very convenient with light-colored urines containing over 1% 
of sugar. Dark or dense urines must undergo a tedious pro- 
cess of decoloration, and where small amounts of sugar are 
present the results are inaccurate. If time is at hand, full 
details of this method may be obtained from the demonstrator, 
and analyses conducted with the polariscope. 
BILE PIGMENTS. 
Urine containing bile coloring matters usually has a greenish shade, 
and a yellow foam forms on shaking. Bile pigments appear in the 
urine several days before the icteric coloration of the skin is perceptible. 
They also appear after internal haemorrhage and phosphorus poisoning. 
354. 1. Gmelin’s Test for Bile Pigments. Take an inch of 
strong HN03 in a test tube. Drop in one tiny crystal of 
white sugar and heat. A lemon-colored acid is produced, due 
to the presence of a little nitrous acid. Carefully overlay 
this with urine containing bile pigments. A play of colors 
gradually appears at the zone between the fluids—green, blue, 
violet, red and yellow. See 302. 
2. Huppert's Modification of this test is more delicate. To URINE. 
161 
the suspected urine add lime water and sodium carbonate. 
A ppt., consisting of lime pigments, falls. Collect and wash 
this ppt., spread it evenly on a white surface, and touch with 
a drop of yellow HN03. A trace of bile pigments yields 
immediately the beautiful colors of Gmelin’s reaction. 
BLOOD. 
Bloody urine is of a reddish to brown color, and always contains 
albumin. When blood has a renal origin, the color is usually evenly 
diffused through the urine. In vesical haematuria clots are common, and 
blood appears more abundantly at the close of micturition. The detec- 
tion of blood casts by the microscope is the most conclusive proof of 
the renal origin of haematuria, common in Bright’s disease. 
355. The Coagulation Test for Blood. Add 2 drops of acetic 
acid to the suspected urine, and boil. If the coagulated albu- 
min be tinged red, haemoglobin is indicated. 
356. The Guiacum Test for Blood. To the suspected urine, 
rendered slightly acid if alkaline, add 5 drops of fresh tinc- 
ture of guiacum. Shake, and add a few drops of hydrogen- 
dioxide. If blood is present, the solution turns blue. Pus, 
spermatozoa, etc., yield the same test. See 313. 
357. The Microscopical and Spectroscopical Test. Examine 
a sample of bloody urine with a high power of the micro- 
scope, and observe the blood corpuscles. Note that they do 
not tend to form rouleaux. In old urine their appearance is 
often so jagged and swollen as to be quite indistinguishable. 
The spectroscope may be used to detect blood, as in 315. 
Urine containing pus always gives the test for albumin. The urine is 
usually turbid. The microscope will reveal the nucleated pus corpuscles. 
PUS. 162 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
358. Donne’s Test for Pus. Let the urinary sediment set- 
tle. Decant the supernatant urine. Add KOH to the de- 
posit. Pus, if present in any considerable quantity, at once 
assumes the form of a glairy, gelatinous mass. 
ERLICH’S DIAZO REACTION. 
This reaction is claimed to be of value in the prognosis of typhoid 
fever and pulmonary tuberculosis. The reaction is thought to be yielded 
in these and a few other diseases from the presence of “aromatic sub- 
stances ’’ produced in the course of the disease. 
359. Process. Mix 50 parts of the sulphanilic acid solution1 
and one part of the sodium nitrite solution1. Add an equal 
quantity of urine, and render the whole strongly alkaline with 
ammonia. If the reaction be positive, the solution assumes 
a carmine red color, which appears on the foam when the 
solution is shaken. Normal urine yields a yellow color. 
LABORATORY QUESTIONS. 
1. What proteids are found in the urine? Which, clinically, is the 
most important? 
2. What are some of the causes of albumin in the urine ? 
3. Which test for albumin in your hands yields the best results? 
4. How does the presence of albumin affect the specific gravity of the 
urine ? 
5. Why in 341 is it necessary to neutralize the urine with acetic acid ? 
6. What is the weakness of the heat and nitric acid test for albumin ? 
7. What precautions must be observed in applying Heller’s test? 
8. Why should the acid and urine not be mixed in Heller’s test ? 
9. In the ferrocyanide test, what advantage results from adding the 
KjFeCye before the acid? 
Note i. The sulphanilic acid solution is prepared by dissolving 2 grams of the 
sulphanilic acid in 50 c.c. of HC1 and making up to 1,000 c.c. with distilled water. The 
sodium nitrite solution is prepared by dissolving 1 gram of sodium nitrite in 200 c.c. of 
distilled water. These solutions when mixed, liberate diazo-sulpho-benzol. URINE. 
163 
io. What causes the inaccuracy of Esbach’s quantitative test? 
ix. Would Esbach’s test be more accurate if picric acid were replaced 
by K4FeCy8 and acetic acid? 
12. Of what clinical value is the detection of albumin? 
13. Will Fehling’s test detect all the various sugars in the urine ? 
14. How does the presence of sugar affect the specific gravity of the 
urine ? 
15. Write the reaction occurring when KOH is added to CuS04 solu- 
tion. 
16. Why is it not advisable to use a Fehling’s solution made with 
Rochelle salt? 
17. In case one uses Rochelle salt, how can the solution be proved 
good ? 
18. What is the greenish precipitate found often in the copper tests for 
sugar ? 
19. Why should urine be added to Fehling’s solution in small amounts? 
20. What are the fallacies of Bottger’s bismuth test? 
21. Which is the most delicate sugar test? 
22. Why is ammonia used in Fehling’s quantitative test? 
23. Why does Fehling’s quantitative solution resume its blue color? 
24. What is the highest per cent of sugar yet found in your analyses? 
25. How may the nucleus of pus corpuscles be brought into view ? 
26. What is a pus corpuscle? 
27. Report the abnormal constituents and the quantities present, where 
possible, in bottles D-M, using the printed blank for urinalyses. 
28. Will chloroform reduce Fehling’s solution? Will chloral? Try 
it, and note also the chloroform odor evolved. 
29. What preserving agent could be added to urine that would not 
interfere with the tests for sugar and albumin?  
DOES NOT BURN, 
or but slightly chars, or leaves a relatively 
large residue. 
DOES BURN. 
Moisten some fresh powder with HC1. 
Effer- 
Does not effervesce. 
With a flame. 
Without a flame. 
vesces. 
Dissolve a 
Add HC1 to some fnsed powder, and heat. 
Colored. 
Apply the Murexid Test. 
bit in HC1, 
neutralize, 
and test by 
165-3- 
Effervesces, 
Does not effervesce. 
Moisten fresh powder 
Yellow. 
Pale 
yellow. 
Bine. 
Purple color. 
Moisten fresh nowder 
No reaction. 
Dilute, neu- 
with KOH and warm. 
Continuous 
Transient. 
with KOH, 
and warm. 
tralize and 
test for Ca 
Odor of 
Continuous 
Odor sharp. 
uble in HNO3 
Calcium 
Odor of 
without effer- 
carbonate. 
by 165-3. 
Odor of 
No odor of 
burning 
Powder sol- 
vescence; eva- 
Calcium ox- 
nh3 
NH3, or only 
feathers. 
burning 
NH 4. 
NH4 
porated leaves a 
(Rare.) 
abundant. 
traces. 
Powder sol- 
rosin. 
uble in 
yellow residue, 
alate. 
Powder solu- 
Powder sol- 
uble in al- 
NH4OH 
turning to 
(Common.) 
uble in HC1, 
and sol., 
ble in HC1, 
uble in al- 
cohol and 
and evapo- 
rates leav- 
urate. 
(Most 
red when 
touched with 
rendered al- 
ether. 
cohol and 
ing6 sided 
(Common.) 
common.) 
KOH and 
kaline with 
Fibrin. 
ether. 
plates. 
heated. 
NH4OH, 
NH4OH, 
(As a nu- 
Urostealith 
Cystin. 
Xanthin. 
gives a crys- 
talline ppt. 
gives an 
amorphous 
cleus.) 
(Rare.) 
(Rare.) 
(Rare.) 
Triple phos- 
phates. 
(Common.) 
Earthy phos- 
phates. 
(Common.) 
Cut the calculus across with a saw. Pick out and powder homogeneous portions. Test separately portions which appear to differ. 
To Detect the Prevailing Constituents of Urinary Calculi. 
Heat a bit of the powder on platinum foil. 
TABLE IV. LABORATORY EXERCISES 
IN THE 
TOXICOLOGY 
OF THE COMMON 
IRRITANT AND NEUROTIC 
POISONS TOXICOLOGY. 
167 
TOXICOLOGY. 
CLASS I. IRRITANT POISONS. 
Beside the more common poisons of this class mentioned in the brief 
exercises below, there is a large number of rarer substances which, 
taken in sufficient quantities, are known to produce violent irritant 
effects. Among these may be mentioned chlorine, bromine, potassium 
chlorate, cream of tartar, alum, bismuth subnitrate, salts of barium, 
gold, silver, platinum, zinc and chromium, castor beans, savine, helle- 
bore, colchicum, gelsemium, cantharides; poisonous mussels, mush- 
rooms, sausage, cheese, etc. 
General Symptoms of Irritant Poisons. From a physician’s stand- 
point, poisons are most conveniently classed by their physiological 
action. This classification is not an inconvenient chemical one, as it 
likewise broadly divides the poisons into metallic poisons and alkaloids. 
The general symptoms of irritant poisons include all phenomena 
which indicate irritant action upon the mucous lining of the alimentary 
canal, such as nausea, vomiting, purging, abdominal pains, cramps, etc. 
Vomited and purged matters are often bloody, and post mortem exami- 
nations show more or less gastro-intestinal inflammation, sometimes 
ulceration, perforation and gangrene, due to secondary processes. 
ARSENIC. 
360. Microscopical Appearance of Arsenous Oxide. With the 
microscope examine several different samples of arsenous 
oxide, As203. Note how each differs in the proportions of 
amorphous powder, broken and perfect octahedral crystals, 
their size, brilliancy, etc. The source of poison used can 
often be thus identified. 
361. Solubility of Arsenous Oxide. Take four test tubes 
three-fourths filled with water. Add to each exactly equal 
quantities of arsenous oxide about the size of a pin’s head. 168 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
No. 1 dissolves slowly in the cold. 
No. 2 dissolves more rapidly when heated. 
No. 3 dissolves readily on addition of HC1. 
No. 4 dissolves quickly on addition of NaOH. 
362. Odor and Taste of Arsenous Oxide. Heat a bit of 
metallic arsenic on charcoal before the blowpipe. It burns 
with a bluish white flame, and emits dense white fumes of 
As203, with a garlic odor. Touch a little arsenous oxide for 
a moment to the tongue, and observe that it is almost with- 
out taste. 
363. General Reactions of Arsenic. Make a solution of 
“ Rough on Rats” by boiling a pinch with dilute HC1. 
Using this as an arsenic solution, turn to 141, and confirm 
all the general reactions of arsenic which are not well in 
mind. 
364. Comparison of Colored Sulphides. Pass H2S, from the 
generator in the hood, through four different test tubes 
containing solutions of arsenic, cadmium, antimony and stan- 
nous salts. Notice the colored precipitates in each instance. 
Confirm the following conclusions by which arsenic and 
antimony can be separated and identified : 
(NH4)2S2 
NH4OH 
KOH 
Cold HC1 
Hot HC1 
Arsenous Sulphide 
Antimony Sulphide 
Cadmium Sulphide 
Stannous Sulphide 
Soluble. 
Soluble. 
Insoluble. 
Soluble. 
Readily sol. 
Insoluble. 
Insoluble. 
Ne’rly insol 
Soluble. 
Soluble. 
Insoluble. 
Insoluble. 
Insoluble. 
Soluble. 
Soluble. 
Soluble. 
Slightly sol. 
Soluble. 
Soluble. 
Soluble. 
365 Action of Antidote—Ferric Hydroxide. 
(a) Preparation. Precipitate a solution of FeCl3 with 
NH4OH. Strain it through muslin, and collect the moist 
red ferric hydroxide, Fe(OH)3. Twelve parts of this is an 
antidote for 1 part of As203. It may be freely administered. TOXICOLOGY. 
169 
(b) Demonstration of Efficiency. Divide a solution of 
arsenic between two test tubes. Shake the contents of one 
with the antidote prepared. Filter, and pass H2S from the 
generator in the hood through both solutions. In one yel- 
low As2S3 is precipitated ; in the other no precipitate proves 
the removal of the arsenic. 
Reaction— 
4Fe(0H)3-j-As203=Fe3(As04)2-|-5H20-(-Fe(0H)2. 
366. Rapid Detection of Arsenic.—Fleitmanri s Test. In a 
test tube cover a little pure zinc with strong NaOH. Cap 
the tube with a piece of paper wet with a drop of AgN03 
solution. Heat nearly to boiling. H is evolved, and, if the 
materials are pure and arsenic free, the paper remains 
unstained. Add a little suspected arsenic solution and boil 
again. If arsenic be present, AsH3 is evolved, which stains 
the AgN03 spot bluish black. Antimony does not give this 
reaction. 
Reactions—Zn-j-2NaOH=H2-f-Na2Zn02. 
AsH3-j-3H20-(-6AgN Ag2. 
367. Rapid Examination of Paris Green. Place in the 
bottom of a clean, dry test tube a little paris green, Cu2- 
(C2H302)-CuHAs03. Have the sides of the tube clean. 
Heat the bottom very hot. Smell the acetic vapors rising. 
Observe the white crystals of As203 sublimed upon the sides 
of the tube, and the reddish copper in the bottom. Care- 
fully dissolve out some of the As203 in a little distilled 
water. Test it by adding a few drops of AgN03, touch- 
ing it with dilute NH4OH, and obtaining the yellow precipi- 
tate of Ag3As03. See 141-3. 
368. Examination of Arsenic Stains on Decomposed Tissue. 
Examine the museum specimens of the mucous mem- 170 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
brane from the stomachs of victims of arsenic poisoning. 
Note in some cases the diffused yellow stains of arsenous 
sulphide formed by the presence of H2S in the decaying 
tissue. Observe in other cases the distinct figured patches 
of yellowish As2S3 formed about undissolved particles of 
As2Os imbedded in the mucous membrane. 
369. Separation of Arsenic from Organic Matter. Place the 
finely minced tissue containing the poison in a large 
evaporating dish. Cover it with water. Add its volume 
of strong HC1. Boil it, and every half minute add a pinch 
of KCIO3, with stirring, until the solids all dissolve to a 
clear yellow liquid. Continue to boil until all the chlorine 
odor is removed, adding water if it becomes too thick. 
Strain it through muslin, then through filter paper, and set 
one-half aside for emergencies. Use the other half for 
quantitative separation by Marsh’s test, as follows : Fit a 
flask with a thistle tube and a long delivery tube of hard 
glass drawn out to x/s its diameter at three points. (See 
sample on the demonstration desk.) Support this on a ring- 
stand. Place a handful of pure mossy zinc in the generator. 
Cover the zinc with water, and add moderately strong H2S04 
until a slow evolution of hydrogen occurs. Heat the deliv- 
ery tube to dull redness with a Bunsen burner at a point two 
inches in front of one of the constricted portions. After the 
gas has passed for 20 minutes, if no stain appears on the 
glass the materials may be considered pure. Light the two 
other burners necessary to heat the tube to dull redness at 
the two other corresponding points. Slowly drop in the 
arsenic solution through the thistle tube, and continue the 
heat and slow evolution of gas until a burner transferred to 
a new point on the glass no longer deposits a stain, showing 
that the arsenic has been entirely removed from the solution. TOXICOLOGY. 
171 
With a triangular file next cut out such portions of the tube 
as contain arsenic mirrors. Weigh these accurately on a 
good balance. One of them may be heated, and crystals 
of As203 identified by the microscope. Boil them all in 
a test tube of dilute HN03, and dissolve out the arsenic. 
Wash the tubes, dry, and weigh them. The difference in 
weighings gives the weight of metallic arsenic. 
The solution in the test tube may be nearly neutralized 
by NH4OH, and the arsenic identified by the following tests : 
(1) The ammonio-silver test, 141-3. 
(2) The sulphide test, 141-1. 
LABORATORY QUESTIONS. 
1. Write the reaction when As203 dissolves in water; in KOH. 
2. What is white arsenic? Orpiment? Realgar? Ratsbane? 
3. Of what value is the microscopical examination of AS2O3? 
4. Can you detect arsenic in the sample of green wall-paper fur- 
nished ? 
5. How would you quickly detect Fowler’s solution? 
6. What is the principal constituent of “rough on rats”? 
7. What is paris green ? London purple ? 
8. Why is arsenic such a dangerous poison? 
9. What could be used in preparing the As antidote, if ammonia 
was not at hand ? 
10. In what form is arsenic dissolved when the tissue is put into 
solution by chlorine, as in 369? 
11. Are eggs, milk or soap useful as antidotes? Try the action of 
each. 
ANTIMONY. 
370. Properties of Metallic Antimony. Examine a bit of 
metallic antimony. Notice that it is extremely brittle, 
insoluble in alkalies and strong hot HN03, but soluble in a 
mixture of HC1 and HNOg. Heated on charcoal before the 
blowpipe flame, odorless white fumes of Sb203 are evolved 
(distinction from arsenic). 172 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
371. Examination of Tartar Emetic, KSbO(C4H4Oc). 
1. It has a nauseous, styptic, acrid taste. 
2. It chars when heated, like all tartrates. 
3. Heated on charcoal before the blowpipe, it yields 
brittle metallic beads of Sb, which volatilize to Sb203. 
4. It is freely soluble in water. 
5. Its solutions redden litmus paper. 
6. Its solutions are pptd. by HC1, NaOH, Na2C03, and 
alcohol. 
7. Touched with H2S or (NH4)2S, it turns orange-yellow 
from the formation of Sb2S3. 
8. A drop of strong solution evaporated spontaneously on 
a glass slide leaves beautiful rhombic crystals, seen under 
the microscope. 
372. General Reactions of Antimony. Make a solution of 
tartar emetic. Turn to 142, and review such of the reac- 
tions of antimony as are not clearly in mind, noting the dis- 
tinction from arsenic. 
373. Action of Antidotes. 
1. Ferric Hydrate. Prepare some fresh ferric hydroxide, 
as in 365 a, and, using a solution of tartar emetic, prove in 
like manner that Fe(OH)3 is an antidote for antimony. 
2. Tannin. To a solution of antimony add a strong solu- 
tion of tannin. Note the ppt. formed. It may be filtered, 
and the absence of antimony proved in the filtrate by H2S. 
374* Rapid Detection of Antimony in Solutions. Evaporate 
a small portion of the suspected solution to a small bulk 
with two drops of HC1. Pour the concentrated liquid into 
water. If antimony is present, a white precipitate of anti- 
mony oxychloride falls, insoluble on addition of tartaric acid 
(distinction from bismuth, 139-2). TOXICOLOGY. 
173 
375. Examination of Antimony Stains on Decomposed Tissue. 
Examine the museum specimens of the mucous membrane 
from the stomachs of victims of antimony poisoning. Note 
the dark orange stains of Sb2S3, and the golden tinge as the 
light shines through the tissues. Compare these stains with 
those of arsenic. 
376. Separation of Antimony from Organic Matter. This 
may be accomplished, and the antimony weighed, by the 
method used for arsenic, 369. The examination of the anti- 
mony mirror is conducted according to the general reactions 
of antimony, 142. 
375. Separation of Both Arsenic and Antimony from Organic 
Matter. When both arsenic and antimony are found to be 
present, two principal methods are in use for their separa- 
tion. The minced tissues are put into solution by HC1 
and KCIO3, as under arsenic, 369. Divide the solution into 
three parts. Put one aside for emergencies. Use y$ for 
each of the following methods : 
Method I. Separation by Marsh's Test. Prepare a 
Marsh’s apparatus from a flask, thistle tube and short de- 
livery tube. Start the action, and test the materials as under 
arsenic, 369. Next pass the gas through a strong solution of 
AgN03, and feed the suspected fluid, drop by drop, to the 
generator through the thistle tube. If arsenic or antimony 
be present, AsH3 or SbH3, or both, are evolved, and form a 
black precipitate with AgN03. Allow the action to continue 
until the gas, when passed through a little fresh AgN03, 
produces no precipitate. (In case any forms, it must, of 
course, be added to the original AgN03 solution.) Filter. 
The filtrate contains soluble arsenic, and the precipitate 
consists of Ag and Ag3Sb. 174 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
(a) Filtrate. Carefully neutralize the solution with dilute 
NH4OH, and a yellow ppt. of Ag3As03 indicates arsenic, 
Hi-3- 
(b) Precipitate. Boil the black precipitate with a little 
HC1 and a few drops of HN03. Dilute, and filter off the 
white AgCl. Antimony in the filtrate is proved by passing 
H2S through the solution, which yields the orange-red pre- 
cipitate of Sb2S3. 
Method II. Separation by Hydrogen Sulphide. Any 
arsenic present after solution by HC1 and KC103 is left in the 
condition of arsenic acid, H3As04, which is not readily pptd. 
by H2S (see 141-1). Boil it with Na2S03 until the solution 
smells strongly of S02, to reduce arsenic to the arsenous con- 
dition. Boil off the odor of S02. While warm, pass H2S 
through the liquid for some time. As2S3 and Sb2S3 precipi- 
tate, with some organic matter by which the color of the 
sulphides may be modified to a dirty brown. Filter out and 
wash the sulphides. As they lie on the filter, repeatedly 
pour over them 15 c.c. of strong NH4OH. As2S3 will dis- 
solve and Sb2S3 will remain on the filter. See 364. 
(a) Filtrate. Evaporate to dryness, mix with K4FeCy6; 
insert the mixture in a tube, heat, and metallic arsenic sub- 
limes. Cut the tube, reheat, and identify the octahedral 
crystals of As203 with the microscope. These may be dis- 
solved in H20 and tested : 
(1) By the silver-ammonio test, 141-3. 
(2) By the hydrogen sulphide test, 141-1. 
(b) Residue. Dissolve the residue by boiling it with a 
little concentrated HC1, dilute, filter, if necessary. Pass 
H2S through a portion of the solution, and the orange-red 
Sb2S3 falls. Another portion may be concentrated and 
poured into water, yielding antimony oxychloride, 142-4. TOXICOLOGY. 
175 
LABORATORY QUESTIONS. 
1. What is butter of antimony? Black antimony? Kermes mineral? 
2. What is the most common form in which antimony is admin- 
istered? 
3. How may arsenic and antimony sulphides be distinguished by their 
solubility ? 
4. Why is tartar emetic incompatible with HC1 ? 
5. Name as many substances as possible incompatible with solutions 
of antimony. 
6. What is the powder of Algaroth ? 
7. Is Fe(OH)3 as perfect an antidote for antimony as arsenic? Why? 
8. Are eggs, milk and soapsuds antidotes to antimony? Try them, 
and see. 
9. How would you quickly examine a substance, solid or liquid, to 
see if it contained antimony? 
10. How might an antimony mirror be dissolved from a glass tube? 
MERCURY. 
378. Properties of Corrosive Sublimate. Make a strong 
solution of mercuric chloride, HgCl2. Note its limited solu- 
bility, its salty, styptic, powerful taste. The solution red- 
dens blue litmus paper. Save the solution for the following 
exercises. 
379. General Reactions of Mercury. Turn to 137 and 138, 
and confirm any reactions of mercurous and mercuric com- 
pounds that are not fully in mind. 
380. Action of Antidotes. 
1. Albumin. Shake some white of egg in a test tube 
with HgCl2 solution. Observe the formation of the insoluble 
mercury albuminate. Compare this reaction with 268. 
2. Casein. Shake some milk in a test tube with HgCl2 
solution. The casein is precipitated. 
3. Tannic Acid. Add a strong solution of tannin to a 
solution of HgCl2, and note the insoluble precipitate formed. 176 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
381. Rapid Identification of Mercury Compounds. Mix in a 
test tube any mercury compound, like calomel or HgCl2, 
with dry Na2C03. Heat, and a mirror of metallic mercury 
forms on the tube. 
Reaction—HgCl2-|-Na2C03=2NaCl-|-C02-j-0-|-Hg. 
382. Rapid Separation of Bichloride with Ether. Liquids, 
vomited matters, etc., containing soluble corrosive sublimate 
may have this salt removed by shaking the material with 
commercial ether. Decant and evaporate the supernatant 
ether. Crystals of HgCl2 will be left nearly pure, which 
turn scarlet when touched with KI solution. Ether will 
dissolve about 60 per cent of the corrosive sublimate. 
383. Separation of Mercury from Organic Matter. 
(1) Boil the minced material, containing HgCl2, for 
some time, with water acidulated with HC11. Strain the 
liquid off through muslin. Boil the matter again with fresh 
acid solution. Strain this off and add it to the first extract. 
Filter this mixture through filter paper and evaporate to 
one-fourth its volume. Set aside half for emergencies. 
(2) Take half the warm solution and insert in it a piece 
of bright copper foil or wire, which soon becomes covered 
with a greyish white deposit of metallic mercury, if that 
metal be present even in minute quantities. This process is 
known as Reinsch’s test, and may be continued until all the 
mercury has been removed. Put several of these small slips 
up into a glass tube drawn out like a dropper to a long, fine 
capillary opening. Heat the tube near the copper, and the 
mercury will sublime into the capillary neck and form a ring 
Note i.—Whenever solutions of mercury have come in contact with albumin or 
mucous membrane, insoluble mercury compounds have been formed, and considerable 
boiling is necessary to get the metal again into solution. TOXICOLOGY. 
177 
of well-defined globules under the microscope. A crystal 
of iodine pushed up into the cooled tube and left for some 
hours will slowly volatilize and form Hgl2, turning the mer- 
cury ring scarlet. 
LEAD. 
384. Examination of Metallic Lead. Heat a mixture of lead 
acetate and sodium carbonate on charcoal until a small 
metallic bead is obtained. Hammer it out, and note that it 
is malleable and will mark on paper. Heat the bead very 
hot, and notice the yellow incrustation of PbO formed on 
the charcoal. The metal readily dissolves in HN03. 
385. Properties of Lead Acetate. Lead acetate, Pb(C2H302), 
is the most frequent cause of acute lead poisoning. Con- 
firm the following facts : 
1. It has a sweet, astringent taste and acetous odor. 
2. It crystallizes from strong solutions in 4-sided prisms, 
seen under the microscope. 
3. It dissolves in ordinary water to a milky fluid. 
4. A crystal touched with KI turns yellow. 
5. A crystal touched with a solution of H2S turns black. 
6. Heated in a test tube, acetous fumes arise. It slowly 
chars and leaves a reddish brown lead oxide. 
386. General Reactions of Lead. Make a solution of lead 
acetate, turn to 136 and confirm all the reactions for lead 
that are not clearly in mind. 
387. Action of Antidotes. To a solution of lead add the 
following antidotal reagents : 
1. Magnesium sulphate, MgS04, ppts. insoluble PbS04. 
2. Albumin ppts. insoluble lead albuminate. 
3. Soap ppts. insoluble lead stearate, etc. 178 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
388. Separation of Lead from Organic Matter. Boil the 
minced material with water strongly acidulated with HN03 
(see Note 1, under Mercury, 383). Strain, filter, nearly 
neutralize, concentrate, precipitate by H2S and test the 
PbS2 by dissolving it in a little HN03 and applying the 
general tests, 136. If lead is present in any quantity, this 
will always detect it. If sulphates, as antidotes, have been 
given, the tissues must be incinerated, the ash dissolved in 
HN03, and tested. 
COPPER. 
389. Examination of Verdigris. 
(a) Natural Verdigris. Examine some of the green com- 
pound formed on copper or brass by the action of moisture 
and the atmosphere. It is Cu0CuC03. Observe that it 
effervesces with a drop of acid. 
(£) Commercial Verdigris. Cover a copper cent, or any 
piece of copper, with acetic acid. Set it aside, and observe 
the green copper acetate, Cu(C2H302), formed. This resem- 
bles commercial verdigris, which is usually copper oxyace- 
tate, Cu0(C2H302)2. Using commercial verdigris, confirm 
the following facts : 
1. It is nearly all soluble to a green solution, leaving a 
little basic residue. 
2. It all dissolves on addition of a few drops of HC1. 
3. It has an acetous odor, stronger when heated. 
4. It has the styptic taste peculiar to copper compounds. 
390. General Reactions of Copper. Turn to 140, and, using 
a solution of copper, confirm the general reactions not 
familiar. TOXICOLOGY. 
179 
391. Action of Antidotes. With a solution of copper, con- 
firm the following antidotal reactions : 
1. Albumin ppts. bluish insoluble copper albuminate. 
2. Potassium Ferrocyanide ppts. brownish red Cu2FeCy6, 
insoluble in dilute acids. 
3. Soap ppts. insoluble blue copper stearate, etc. 
392. Rapid Identification of Copper in Solution. Slightly acid- 
ulate the solution, which will always be blue or green if 
copper is present, with HC1. Insert a bright steel needle. 
Let it remain 5 minutes. Examine the red deposit of copper 
on it. See how dilute a solution of copper will give this 
reaction. 
393. Examination of Paris Green. The most dangerous in- 
gredient in paris green, Cu(C2H302)- Cu(HAs03), is arsenic, 
as seen in 367. The green color is due to copper. Make a 
solution, add NH4OH, observe the white precipitate first 
formed, and later the deep blue solution indicative of copper. 
394. Separation of Copper from Organic Matter. The detection 
of copper presents no difficulty. The material is extracted 
with acidulated water, strained, filtered, concentrated, pre- 
cipitated by H2S, the sulphide dissolved in HN03 and tested 
by the general reactions, 140, or quantitatively by 182. 
LABORATORY QUESTIONS, 
1. What poison is often eliminated by the saliva ? How could it there 
be detected? 
2. How can calomel and corrosive sublimate be distinguished by 
touching them with KOH ? 
3. Is calomel soluble in water? 
4. Describe a rapid method of detecting mercury, either in a solution 
or as a solid. 
5. What is vermilion? What is amalgam? 
6. What is red precipitate? What is cinnabar ? What color is it? 180 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
7. What other lead salts besides the acetate are used in medicine? 
8. What is red lead ? White lead ? Sugar of lead ? 
9. What substances are incompatible with lead in solution ? 
10. Is lead chloride soluble in acids ? In cold water ? In hot water ? 
11. Will pure water dissolve lead? 
12. Will aerated water dissolve lead? 
13. What effect has the presence of organic compounds on the solu- 
bility of lead in water? 
14. How could canned goods contain lead? 
15. What is blue stone? 
16. What is Scheele’s green and Schweinfurt’s green? 
17. After what antidotes must emetics be given, and why? 
PHOSPHORUS. 
395. Properties of Phosphorus. Review experiments 99 
and 100 on the forms and solubility of phosphorus, if not 
clearly in mind. 
396. Action of Antidotes. 
(a) Copper Sulphate. Pour a solution of CuS04 on a 
small piece of waxy phosphorus. Notice after a few moments 
the coating of insoluble black metallic copper and copper 
phosphate formed about the phosphorus. 
(b) Old turpentine and hydrogen dioxide are advised to 
oxidize the phosphorus to phosphoric acid, followed by 
alkalies to neutralize the acid. 
397. Detection of Free Phosphorus. Phosphine Test. Prepare 
an active hydrogen generator and light the gas. Note 
the dim blue flame. Pour in through the thistle tube a solu- 
tion containing scrapings from a match’s head. Take the 
tube into the dark. Observe the luminous vapors rising in 
the generator, and that the flame burns green with an outer 
blue mantle. When the flame is extinguished, the gas has 
the garlic phosphorus odor. TOXICOLOGY. 
181 
CARBOLIC ACID, or PHENOL. 
398. Properties of Carbolic Acid. Examine carbolic acid, 
or phenol, C6H5OH, and confirm the following facts : 
1. It exists as a crystalline solid, which, when warmed 
with 1 q°/0 °f water, remains a liquid. 
2. The clear liquid turns red on long exposure to light. 
Examine acid which has been so exposed. 
3. It has a strong characteristic or “ carbolic” odor. 
4. It closely resembles creosote. Examine wood creosote. 
5. It is not acid, but leaves a greasy stain on blue litmus 
paper. 
6. It dissolves with difficulty when shaken with water. 
7. It has a biting taste, and the strong acid raises a white 
blister on the skin. 
399. General Reaction of Carbolic Acid. Turn to 226, and 
review such general reactions of carbolic acid as are not 
familiar. 
400. Action of Antidotes. To a solution of carbolic acid 
add the following reagents : 
(#) Saccharate of Lime. Prepare by pouring water, 
sweetened with cane sugar, on quicklime, and after standing, 
decant or filter. A saccharate of lime forms, which increases 
the amount of lime in solution. Otherwise lime water is as 
good. A white ppt. falls. 
(b) Soap water forms a white ppt. 
(V) Magnesium Carbonate solutions form white ppts. 
(</) Albumin forms a gelatinous ppt. 
401. Detection in Organic Solutions. The characteristic 
odor readily identifies carbolic acid. It may be readily 
detected in urine, vomited matters, etc., by shaking with 182 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
ether. Decant the supernatant ether, evaporate, and the 
carbolic acid is left as a minute drop with its characteristic 
qualities, 226. 
OXALIC ACID. 
402. Resemblance to Epsom Salt. Oxalic acid, C2H204, the 
strongest of the vegetable acids, has often been mistaken 
for Epsom salt, or magnesium sulphate, MgS04. Confirm 
the following differences: 
Oxalic Acid. 
Epsom Salt. 
Heated . . . 
Volatilizes. 
Does not volatilize. 
Taste . . . 
Sour. 
Bitter. 
Reaction . . 
Acid. 
Neutral. 
NH4OH . . 
Does not ppt. sol. 
Ppts. solution. 
403. General Reactions of Oxalic Acid. Turn to 213, and 
confirm any reactions of oxalic acid not clearly in mind. 
404. Action of Antidotes. 
Alkaline earths. 
(a) Prove that NaOH, KOH, NH4OH, Na2C03, etc., 
compounds of the alkali metals, neutralize oxalic acid, 
H2C204, without precipitation. The soluble oxalates are as 
poisonous as the acid, hence these alkalies are not antidotes. 
(£) Prove that lime water, or milky mixtures of chalk or 
magnesia, or solutions of magnesium carbonate, will neu- 
tralize solutions of oxalic acid, producing insoluble precipi- 
tates. Hence these are antidotes. 
405. Detection of Oxalic Acid in Organic Matter. Solutions 
containing much organic material, like vomited matter, TOXICOLOGY. 
183 
may be tested for oxalic acid by being well digested (water 
being added, if necessary), the solution strained, filtered, 
concentrated, and a portion tested by CuS04. Free oxalic 
acid precipitates bluish CuC204, which differs from other 
copper precipitates in being insoluble in moderately concen- 
trated HN03 and HC1. Further concentration will usually 
allow the acid to crystallize on cooling. When antidotes 
have been given, the detection is more complicated. 
CAUSTIC ACIDS AND ALKALIES. 
These substances are so common, their tests so frequently 
referred to, their neutralization so well understood and their 
presence in strong solutions used as poisons so readily de- 
tected by taste and touch, that they will not be further 
considered. 
LABORATORY QUESTIONS. 
1. Why should protective oils not be administered in poisoning by 
free phosphorus? 
2. Would the presence of phosphates in the stomach prove phos- 
phorus poisoning? 
3. Why is old turpentine advised as an antidote to phosphorus? 
4. Are oxalates in rhubarb poisonous? Why? 
5. Would oxalates in the urine prove poisoning by oxalic acid ? 
6. Why are alkalies not antidotes to oxalic acid ? 
7. What are antidotes to the mineral acids? 
8. What are antidotes to strong alkalies ? 
9. How could one detect caustic soda ? 
10. How could one quickly detect sulphuric acid ? 184 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
CLASS II. NEUROTIC POISONS. 
Beside the more common poisons of this class treated of in the fol- 
lowing exercises, there are a large number of rarer substances which, 
administered in larger or smaller doses, produce their toxic neurotic 
effects. Among these may be mentioned hydrocyanic acid, hyoscyamine, 
daturine, hyoscine, salanin, lobeline, conine, alcohol, oil of bitter almonds, 
nitro-benzene, calabar bean, aniline, ptomaines, leucomaines, etc. 
General Symptoms of Neurotic Poisons. The general symptoms of 
neurotic poisons are those arising from specific action on the great nerve 
centers. In general they are drowsiness, giddiness, headache, delirium, 
stupor, coma, and sometimes convulsions and paralysis. There are very 
few antidotes which are chemical in their action. 
INTRODUCTORY SEPARATION OF SOME COMMON 
ALKALOIDS. 
CAFFEINE, or THEINE. 
406. Sublimation of Caffeine. Put a thin cork ring on a 
microscope slide, and in it a pinch of dry, finely powdered 
tea leaves. Cover the ring with another glass slide and warm 
gently. If the upper glass becomes covered with vapor take 
it off, fan it until dry, replace it and continue the gentle heat. 
At about i8o° C. a white, filmy deposit will appear on the 
upper glass. Remove the slide to the microscope and ex- 
amine the beautiful, distinct needles of theine, or caffeine, 
C8H10N4O2. Powdered coffee may be used instead, but con- 
tains a smaller per cent of the alkaloid. 
407. Extraction of Caffeine. Add 5 grams of powdered tea to 
25 c.c. of water. Boil, digest the solution and filter. Repeat 
the process with another 25 c.c. of water. Concentrate the 
united filtrates to 10 c.c., render alkaline with ammonia, and 
shake with 15 c.c. of chloroform in a large test tube. Sepa- 
rate the chloroform with a small glass pipette. Let it evapo- TOXICOLOGY. 
185 
rate spontaneously in a watch glass. When examined under 
the microscope the yellowish white residue may be seen to 
consist of the characteristic radiating needles of caffeine. 
Compare the crystals with a commercial sample of caffeine. 
408, Sublimation of Theobromine. Sublime a pinch of pow- 
dered cocoa bean, as under 406. The needle crystals of caf- 
feine will be observed mixed with the shorter, thicker crys- 
tals of theobromine, C7H8N402. Compare the form of these 
crystals with those of commercial theobromine. 
409. Extraction of Cinchona Alkaloids. Place about 10 g. 
of finely pulverized cinchona bark in a beaker. Cover the 
powder with water, add 10 c. c. of KOH and boil. Pour the 
solution into a large test tube, and, keeping it hot, shake it 
several times with a mixture of 15 c. c. of benzol and 5 c. c. of 
amyl alcohol. This dissolves the alkaloids. Decant the 
alcoholic layer into another large test tube, add 20 c.c. of 
distilled water, slightly acidulate with H2S04 and shake re- 
peatedly. The alkaloids, in the form of sulphates, dissolve 
in the water, which is removed, exactly neutralized with 
NH4OH, evaporated one-half, and divided between two 
watch glasses. 
(1) To one add 2 drops of NH4OH ; a white ppt. falls, 
composed of all the cinchona alkaloids—quinine, quinoidine, 
cinchonine, cinchonidine, etc. 
(2) Note the bitter taste of the other solution, and after 
a time beautiful crystals of neutral quinine sulphate 
(C20H24N2O2)2H2SO4 form. The other alkaloids remain in 
solution. 
4io. Tests for Quinine. 
i. The Fluorescence Test. Acidulate an alcoholic solution 
of quinine with dilute H2S04. A beautiful blue fluorescence 
appears, destroyed by addition of NaCl. 186 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
2. The Thalleioquin Test. To a solution of quinine or its 
salts, add 1 drop of fresh chlorine or bromine water, and ren- 
der alkaline with 4 drops of ammonia. A deep green color 
or ppt. is produced. This test is very delicate. 
EXERCISES ON THE TOXIC ALKALOIDS. 
411. Extraction of Nicotine. Boil a large tablespoon full of 
strong Virginia tobacco with 50 c. c. of water, digest, filter 
and concentrate the filtrate to 5 c.c. Next cool and add 
15 c.c. of strong alcohol. Warm and stir for a few moments, 
when the gummy resinous matters will be coagulated. The 
alcohol is to be filtered off, and contains impure nicotine in 
solution. Evaporate this nearly to dryness. Render slightly 
alkaline with KOH and shake with 15 c.c. of chloroform in 
a large test tube. Separate the chloroform with a pipette. 
Evaporate it in a watch glass. Observe the dark drops of 
nicotine, (C5H7)2N2, left. Note the odor. Its poisonous 
properties may be observed by putting two drops far back on 
the tongue of a small animal. 
STRYCHNINE 
412. Examination of Nux Vomica. Confirm the following 
properties which readily identify the commercial powdered 
nux vomica : 
1. It is a light, chocolate-colored, bitter powder. 
2. It partially dissolves in water to a bitter solution. 
3. Under the microscope the powder seems filled with 
the broken, fibrous hairs from the seed membrane. 
4. It turns deep orange when touched with HN03, 420, b. 
5. It turns brown when touched with a solution of I in TOXICOLOGY. 
187 
413. Solubility of Strychnine. Compare the solubilities of 
strychnine, C21H22N202, and the salts of strychnine, by 
confirming the following table, using a drop of each reagent 
and a tiny bit of the alkaloid. The same is, in general, 
true of all alkaloids: 
Alkaloid. 
Water. 
Chloroform. 
Ether. 
Acids. 
Pure Strychnine. 
Salt of Strychnine. 
Nearly insoluble. 
Soluble. 
Soluble. 
Insoluble. 
Soluble. 
Insoluble. 
Soluble. 
Soluble. 
414. General Alkaloid Reactions. Solutions of strychnine 
salts, and in general all alkaloids, are precipitated by the 
following reagents. These will be referred to under the 
other alkaloids. Confirm these reactions, using a drop of 
the solution on a microscope slide, and touching it with a 
drop of the reagent. 
1. Alkalies.—A white amorphous ppt., becoming crys- 
talline. 
2. Mayer's Solutiond—A white amorphous ppt., becoming 
semi-crystalline. 
3. Metatungstic Acid A—A white amorphous ppt. 
4. I in KI.—Reddish brown ppt., partially crystallizing to 
characteristic crystals. 
5. HgCl2.—White amorphous ppt., becoming crystalline. 
6. PtCl±.—Pale yellow amorphous ppt., soon becoming 
crystalline. 
7. Picric Acid in Alcohol Solution.—Yellow amorphous 
ppt., becoming crystalline. 
8. Tannic Acid.—White amorphous ppt. 
Note i. Mayer’s solution is prepared by adding a solution of KI to a solution of 
HgCl2 until the precipitate first formed redissolves. 
Note 2. Metatungstic acid, orphospho-tungstic acid, is prepared by adding H 3PO4 
to a solution of sodium tungstate as long as a precipitate falls and is redissolved. 188 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
415- Distinctive Strychnine Tests. 
1. Color Test. In the bottom of a porcelain dish put two 
drops of concentrated H2S04. Add a minute granule of 
strychnine. It dissolves clear. Near the acid place a tiny 
crystal of potassium dichromate,1 K2Cr207. Next tip the 
dish so that the acid runs slowly over the crystal. A 
regular succession of colors occurs, blue, violet, purple, and 
red fading to pink. 
This test may be thus performed if the strychnine is in 
strong solution. Add a few drops of K2Cr207, and set aside. 
Characteristic yellow crystals precipitate. These, when col- 
lected and touched with H2S04, develop the above color 
reactions, due to definite oxidation compounds. 
2. Crystal Tests. The crystalline precipitates formed by 
the general alkaloid reagents are valuable for confirmation. 
The branching crystals with I in KI, 414-4, are most charac- 
teristic. 
3. Physiological Test. Take an active frog, and with a 
hypodermatic syringe inject a drop or two of dilute strych- 
nine beneath the skin of its back; grain will kill a frog 
in 15-30 minutes. Observe the characteristic tetanic convul- 
sions, which cannot be confounded with anything but tetanus. 
Note that they occur when the desk is struck or the animal is 
in any way disturbed. 
416. Detection of Strychnine Tablets. A portion of the tablet, 
dissolved in a drop of strong H2S04 and flowed over a 
tiny crystal of K2Cr207, develops the characteristic colors 
directly. In case interfering substances should be present, 
dissolve a portion of the tablet in 5 c.c. of water, render 
Note i. Manganese dioxide, MnC>2 ; lead dioxide, PbOz ; potassium permanga- 
nate, K2M112O8 ; chromic acid, etc., are advocated. 189 
TOXICOLOGY. 
alkaline with ammonia, add 5 c.c. of chloroform, shake, 
remove the chloroform, evaporate it drop by drop in one 
spot on a porcelain dish, cover the spot with a drop of H2S04, 
and let the solution flow over a tiny crystal of K2Cr207, as 
before. The blue to red colors develop. 
417. Detection of Strychnine in Organic Matter. Roger's and 
Girdwood's Method. Digest the comminuted matter with 
water acidulated with HC1, for some time at a moderate 
heat. Strain through muslin, and, if possible, through 
filter paper. If the solution is light colored, and contains 
little organic matter, leave out the next step, in brackets. 
[Evaporate the filtrate to dryness, add to the residue strong 
alcohol, acidulated with a few drops of HC1. Warm, stir, 
filter, evaporate the filtrate to dryness, dissolve the residue in 
acidulated distilled water.]1 Shake this solution with petro- 
leum ether (gasoline), and remove it. Repeat the process 
as long as the gasoline is colored. When the coloring 
matters are thus removed, render the aqueous solution alka- 
line with ammonia, and shake with chloroform twice, each 
time withdrawing the clear chloroform. Evaporate this 
chloroform, in a few spots, on porcelain. Dissolve the 
residue in a drop of concentrated H2S04. If the spot 
blackens, warm it until the organic matter chars, dissolve it 
in a little water, render alkaline, and extract with chloro- 
form as before. Continue this until the residue dissolves 
clear in H2S04, and then apply the color test with K2Cr207, 
415-1, and crystal tests, 415-2. When much decayed or- 
ganic matter is present it is often impossible to get a color 
reaction. The extract still is bitter, and answers the 
physiological test. 
Note i. This step removes much organic matter. LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
190 
BRUCINE. 
418. Solubility of Brucine. Observe that brucine, C23H26- 
N204, resembles strychnine in solubility, but dissolves more 
readily in water and alcohol. 
419. General Alkaloid Reactions. The general reagents, 414, 
precipitate brucine, but less readily than strychnine. 
420. Distinctive Brucine Tests. 
1. Color Tests. 
(a) H2S04.dissolves brucine to a faint rose-red solution, 
which does not yield the strychnine play of colors with 
(b) HN03 dissolves brucine to a deep red solution, pass- 
ing rapidly to yellow when heated. This, cautiously touched 
with a drop of stannous chloride solution, SnCl2, develops a 
purple color. 
2. Physiological Test. Brucine acts on frogs like strych- 
nine, 415-3, but less energetically. 
421. Detection in Organic Matter. Brucine may be detected 
by Roger’s and Girdwood’s method, 417. 
LABORATORY QUESTIONS. 
1. To what are the poisonous qualities of plants due? 
2. Why are alkaloids so called? 
3. What are the peculiarities of the volatile alkaloids? 
4. Which alkaloid so far examined is most highly nitrogenized ? 
5. How does the roasting of coffee affect its strength? 
6. What alkaloid does the kola-nut contain? 
7. Is there any relation between theobromine and uric acid ? 
8. In what forms do alkaloids usually occur in plants ? 
9. What is nux vomica, and what are its alkaloids? 
10. Why does nux vomica turn orange-red when touched with HNO3? 
11. Are alkaloids soluble in water? In ether and chloroform? TOXICOLOGY. 
191 
12. How can alkaloids be rendered soluble in water? 
13. In what chemical form are alkaloids usually administered ? 
14. How could one detect a strychnine tablet in 15 seconds? 
15. Outline the general method of separating alkaloids. 
16. Describe the method of Dragendorff. 
17. Describe the method of Stas and Otto. 
18. How do strychnine colors, 415-1, resemble bile colors, 302? 
19. What is the difference between the sulphate and bisulphate of 
quinine? 
MORPHINE. 
422. Properties of Opium. Examine a piece of opium and 
observe : 
(1) Its bitter, blistering taste. 
(2) Its characteristic odor, clinging even to its solutions. 
(3) Its gummy consistency, or when dry, hard and brittle, 
of a reddish brown color, often mixed with small pieces of 
skin from the poppy pod. 
(4) Aqueous infusions of opium turn red on addition of 
neutral FeCl3, due to the formation of ferric meconate. 
The color is not destroyed by a solution of corrosive sub- 
limate. This test is quite conclusive of opium in solution. 
423. Extraction of Morphine. Powder a piece of opium as 
large as a bean. Boil it with 30 c.c. of water, filter, and 
evaporate the filtrate to 5 c.c. Pour this into a mixture of 
25 c.c. of ether and 10 c.c. of alcohol rendered alkaline with 
strong ammonia. Shake the mixture and set aside for some 
hours. The ethereal solution dissolves part of the alkaloid, 
and the remainder, as impure crystals of morphine, may be 
seen in the bottom. Remove a few drops of liquid contain- 
ing some crystals from the bottom by means of a pipette. 
Examine these under the high power of the microscope, and 
observe their irregular quadrilateral and rounded forms. 192 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
Put some of these tiny crystals on glass and set aside to dry. 
When the following tests are familiar, identify these crys- 
tals as morphine, C17H19N03, by the general and special 
reagents. 
Morphine crystallizes with difficulty from solutions con- 
taining organic matter. With care very good results can be 
obtained by this process. 
424. General Alkaloid Reactions. Apply a drop of each 
reagent in 414 to a drop of strong solution of morphine hy- 
dro-sulphate, and note the precipitation. 
425. Distinctive Morphine Reactions. There is no one reac- 
tion which is absolutely distinctive of morphine. There is, 
however, no crystalline substance but morphine that answers 
the four following tests : 
1. The Sulpho-molybdic Test. Dissolve in two drops of 
H2S04 a crystal of ammonium molybdate. Molybdic acid is 
liberated. A speck of solid morphine touched with this 
immediately dissolves to a momentary crimson-purple color, 
which in ten minutes becomes beautiful deep blue, and grad- 
ually fades. When organic matter is present the pink hue 
is obscured, but the deep blue color usually appears later. 
2. Nitric Acid Test. A drop of HN03 strikes with a 
little morphine a red color, fading to yellow. When this is 
touched with a drop of SnCl2 solution, no purple hue results 
(distinction from brucine). 
3. Ferric Chloride Test. A crystal of morphine, or a drop 
of a concentrated solution, strikes a deep greenish blue with 
a drop of FeCl3, discharged by free acids, alkalies and heat. 
HNOa added turns the color orange. 
4. The Iodic Acid Test. A drop of moderately strong 
morphine solution turns brown when treated with iodic acid, TOXICOLOGY. 
193 
due to the liberation of free iodine. A little starch paste 
first mixed with the iodic acid remains colorless, but turns 
blue when added to morphine. This is a delicate test. 
426. Detection of Morphine Tablets. Usually a bit of a 
morphine tablet touched with a drop of sulpho-molybdic 
solution, 425-1, turns red, and becomes finally deep blue. 
This is a sufficient test. 
When interfering substances are present, dissolve the 
tablet in 5 c. c. of water. Render alkaline with ammonia, 
shake with an equal volume of hot amyl alcohol (or a mixture 
of ether 3 parts and alcohol 1 part). This will dissolve the 
morphine. Separate the supernatant liquid and let it evapo- 
rate on several spots. To these apply the sulpho-molybdic 
test, 425-1, and others, if desired. 
427. Detection of Morphine in Organic Matter. The organic 
matter is digested with water, acidulated with acetic acid, 
at a temperature never exceeding 70° C. (160° F.), strained 
and filtered. The process is repeated, the filtrates are united, 
and concentrated to a small bulk by slow evaporation, at a 
temperature never above 70° C. The solution is then shaken 
with petroleum ether (gasoline), and the supernatant fluid 
removed as long as it removes coloring matters. The solu- 
tion is then once shaken with amylic alcohol to remove fur- 
ther coloring matter. Next render the solution alkaline, 
shake with twice its volume of hot amylic alcohol. The 
amyl alcohol is removed and the process repeated. The 
amyl alcohol, spontaneously evaporated in a watch glass, 
often leaves crystals. When much organic material was 
present crystals can rarely be obtained. Test specks of 
the solid residue by 425-1, 2, 3, 4. Dissolve the remain- 
der in very dilute acetic acid, and test a drop by I in KI, 194 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
414-4, which ppts. yellowish brown amorphous granules, 
becoming, after a time, branching, moss-like crystals, under 
the microscope. 
528. Reactions of Apomorphine. Prepare a little solution 
of apomorphine, C17H17N02, in HC1, and confirm the follow- 
ing reactions : 
1. The Iron Test. A drop of FeCl3 yields an amethyst 
color. 
2. The Nitric Acid Test. Concentrated HN03 yields a 
red color. 
3. The Manganese Test. A few grains of Mn02 yields a 
green color, turned reddish brown by a crystal of oxalic 
acid. 
ATROPINE. 
429. General Alkaloid Reactions. Examine atropine or its 
salts. Note its bitter taste, and its solubility in drops of 
water and chloroform, like other alkaloids. Observe that 
the general alkaloid reagents, 414, precipitate atropine, 
C17H23NO3. 
430. Distinctive Atropine Tests. 
1. Vitali's Test. Touch a bit of atropine with a drop of 
fuming HN03. Evaporate to dryness and touch the residue 
with a drop of a solution of KOH in absolute alcohol. A 
violet color is produced. 
2. Wormley's Test. Saturate a solution of HBr with bro- 
mine. With a drop of this precipitate a drop of an atropine 
solution on a microscope slide. After a time the microscope 
will reveal characteristic crystalline leaf clusters. 
3. Sulphuric Acid Test. A little atropine dissolved in 
strong H2S04 and heated, gives off a fragrant odor of roses. TOXICOLOGY. 
195 
4. The Physiological Test. Place in a cat’s eye one drop 
of a very dilute solution of atropine. The pupil, in the 
course of a few minutes, widely dilates. Dilation produced 
by atropine is more persistant than that produced by any 
other alkaloid. 
431. Detection of Atropine Tablets. The sugar in tablets 
interferes with some direct tests. 
The physiological test with a drop of the solution in a 
cat’s eye is a quick and convenient method. 
The color reaction is easily obtained by dissolving the 
tablet in 5 c.c. of water, rendering alkaline with ammonia, 
shaking with 5 c.c. of chloroform, evaporating the chloroform 
on a few spots and applying Vitali’s test (430-1) and 
Wormley’s test (430-2). 
432. Detection of Atropine in Organic Matter. The method 
of separating atropine from organic matter in general is that 
outlined under strychnine. The temperature should never 
be high, and the residue from the chloroform cannot be 
heated with H2S04 and so purified. Where large amounts 
of putrid matter are present, a crystalline product often 
cannot be obtained. The solution, however, is bitter, and 
dilates the pupil. Other members of the belladonna family, 
it must be remembered, also have this power. 
COCAINE. 
433- General Alkaloid Reactions. Prepare a small amount of a 
solution of cocaine hydrochloride, C17H21N04HC1. Observe 
the precipitates with the general alkaloid reagents, 414. Espe- 
cially notice the microscopical appearance of the character- 
istic stellate crystals formed with PtCl4 and with picric acid. 196 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
434. Distinctive Cocaine Tests. 
1. Vitali's Test. Add to a bit of cocaine a drop of fuming 
HN03, evaporate it to dryness, touch with a drop of alcoholic 
potash and note the odor of peppermint. 
2. Physiological Test. A drop of cocaine solution, as 
strong as 4%, on the tongue produces numbness. 
LABORATORY QUESTIONS. 
1. What alkaloids are extracted from opium? 
2. Why is opium bitter ? 
3. What alkaloid studied is the most difficult to separate ? 
4. What relation does apomorphine bear to morphine? 
5. What alkaloids are related to atropine ? Do they give Vitali’s test ? 
6. Give a rapid method of detecting atropine? 
7. Why is morphine not extracted with chloroform or ether? 
8. What is the source of atropine ? Of cocaine ? 
9. Is morphine soluble in water? In alcohol? 
10. How did morphine receive its name ? 
11. What is meconic acid, and where does it occur? 
12. By what simple test can laudanum be identified? 
13. What alkaloids does cinchona bark contain? 
14. In what ways do ptomaines and leucomaines resemble alkaloids ? TOXICOLOGY. 
197 
TABLE V. 
A Guide in the Rapid Examination of Suspected Matters 
for Common Poisons. 
A thorough examination of the material should be made. Odors may 
detect volatile poisons ; a styptic taste, metallic irritants ; a bitter taste, 
alkaloids ; a sour taste, acids ; a biting taste, alkalies. Solids should be 
examined with the microscope, any seeds, berries, pods, hairs, wing- 
cases, etc., carefully noted. This investigation, with some characteristic 
symptoms, appearances, etc., will nearly always direct to some one of 
the following groups : 
A. Volatile Poisons. 
An acidulated portion heated evolves the odor of 
1. Cyanides. Confirm by i2g-3-b. 
2. Carbolic Acid. Confirm by 401 and 226. 
3. Chloroform. Confirm by 201-b. 
4. Phosphorus. Confirm by 397. 
B. Acids and Alkalies. 
The substance has an acid or alkaline reaction. Test for 
1. Acids. H2S04, 81 and 79; HN03, 98; HC1, 43; 
H3P04, 106; H2C204, 213 and 405. 
2. Alkalies. KOH, 170 ; NaOH, 171 ; NH4OH, 172 and 
odor. 
C. Metallic Irritants. 
Acidulate a portion with HC1 and boil with a piece of 
bright copper. 
1. A Grayish Deposit—Arsenic. Confirm by 141-5 and 366. 
2. A Bluish Deposit—Antimony. Confirm by 374 and 
142-1. 
3. A Bright Deposit when Rubbed—Mercury. Confirm by 
383-2, 381 or 382. 198 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
A needle dipped in the acid solution receives a reddish 
deposit and the solution is green or blue. 
4. Copper. Confirm by 140-2. 
If none of these reactions occur and H2S gives a black 
ppt., it may be 
5. Lead. Confirm by 136-2 and 5 (see 388). 
D. Alkaloids. 
A filtered portion of the solution, acid from HC1, is 
shaken with ether to remove fats and coloring matters, if 
necessary, rendered alkaline with ammonia, shaken with 
chloroform, and the chloroform evaporated on several spots. 
A residue remains. 
1. Strychnine. Confirm by 415-1. 
2. Atropine. Confirm 430-1. Dissolve in acidulated 
water and test by 430-4. 
Another portion shaken with hot amyl alcohol and evapo- 
rated on several spots with gentle heat. 
3. Morphine. Confirm by 425-1 and 4. 
Note. These methods are not searching enough for a legal trial, but are useful 
for clearing up a diagnosis before it is too late. TABLE OF SYMBOLS, VALENCIES AND ATOMIC WEIGHTS. 
199 
TABLE OF SYMBOLS, VALENCIES AND 
ATOMIC WEIGHTS. 
Element. 
Symbol. 
Valency. 
Atomic Weight. 
U. S. P. 
Element. 
Symbol. 
Valency. 
Atomic Weight, j 
U. S. P. 
Aluminum .... 
A1 
IV 
27.04 
Molybdenum . 
Mo 
II IV 
95-9 
Antimony . . . 
Sb 
III V 
119.06 
Nickel . . 
Ni 
II 
58.6 
Argon . .... 
A 
40.? 
Niobium . 
Nb 
V 
93-7 
Arsen um .... 
As 
III V 
74-9 
Nitrogen . 
N 
III V 
14.01 
Barium .... 
Ba 
II 
136.9 
Osmium . . 
Os 
VI 
193. 
Beryllium .... 
Be 
II 
9-03 
Oxygen. . 
O 
II 
15.96 
Bismuth .... 
Bi 
III V 
208.9 
Palladium 
Pd 
II IV 
136 35 
Boron 
B 
III 
IO.9 
Phosphorus 
P 
III V 
30.96 
Bromine .... 
Br 
I 
79.76 
Platinum . 
Pt 
IV 
194-3 
Cadmium .... 
Cd 
II 
in.5 
Potassium 
K 
I 
39.03 
Cesium .... 
Cs 
I 
I32.7 
Rhodium . 
Rh 
II IV 
102.9 
Calcium 
Ca 
II 
39-91 
Rubidium . 
Rb 
I 
85-2 
Carbon 
c 
IV 
11.97 
Ruthenium 
Ru 
II IV 
IOI-4 
Cerium 
Ce 
II IV 
139-9 
Samarium . 
Sm 
III 
149.62 
Chlorine . . . 
Cl 
I 
35-37 
Scandium . 
Sc 
III 
43-97 
Chromium . . 
Cr 
IV 
52- 
Selenium . 
Se 
II IV VI 
78.87 
Cobalt . .... 
Co 
II 
58.6 
Silicon . . 
Si 
IV 
28.3 
Copper 
Cu 
II 
63.18 
Silver . . . 
Ag 
I 
107.66 
Didvmium ... 
Di 
III V 
142. 
Sodium . . 
Na 
I 
23- 
Erbium 
Er 
III 
166. 
Strontium . 
Sr 
II 
87-3 
Fluorine ..... 
F 
I 
19- 
Sulphur 
S 
II IV VI 
31-98 
Gallium . . 
Ga 
III 
69.9 
Tantalum . 
Ta 
III V 
182. 
Germanium 
Ge 
II IV 
72.3 
Tellurium . 
Te 
II IV VI 
125. 
Gold . . . 
Au 
I III 
196.7 
Terbium . 
Tr 
I59.I 
Hydrogen . . . 
H 
I 
I. 
Thallium . 
T1 
I III 
203.7 
Indium 
In 
III 
113.6 
Thorium . 
Th 
II IV 
231.9 
Iodine ... 
I 
I 
126.53 
Tin 
Sn 
II IV 
118.8 
Iridium 
Ir 
II IV 
192.5 
Titanium . 
Ti 
IV 
48. 
Iron 
Fe 
II IV 
55-88 
Tungsten . 
W 
IV 
183.6 
Lanthanum . . . 
La 
III 
138.2 
Uranium . 
U 
II 
238.8 
Lead .... 
Pb 
II 
206.4 
Vanadium 
V 
III V 
51-1 
Lithium ... 
Li 
I 
7.01 
Ytterbium 
Yb 
172.6 
Magnesium . . 
Mg 
II 
24.3 
Yttrium . . 
Y 
III 
88.9 
Manganese . . . 
Mn 
II IV 
54-8 
Zinc .... 
Zn 
II 
65.1 
Mercury 
Hg 
II 
199.98 
j Zirconium 
Zr 
IV 
90.4 200 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
TABLE OF EQUIVALENT WEIGHTS AND MEASURES. 
1 minim rq = .062 c.c. 
60 minims = 1 fluid drachm, fg = 3.697 c.c. 
8 fluid drachms = 1 fluid ounce, f3 = 29-573 c.c. 
16 ounces = 1 pint, O =473.179 c.c. 
8 pints = 1 gallon, Cong. = 3.785 1. 
APOTHECARIES’ FLUID MEASURE. 
x grain gr. = 0.0648 grams. 
20 grains = 1 scruple, = 1.296 grams. 
3 scruples = 1 drachm, 3 = 3.888 grams. 
8 drachms = 1 ounce, 3 = 31.104 grams. 
12 ounces = 1 pound, Bb = 373.242 grams. 
APOTHECARIES’ WEIGHT MEASURE. 
1 inch = 2.54 centimeters. 
12 inches = 1 foot = 30.48 centimeters. 
3 feet = 1 yard = 91.44 centimeters. 
ENGLISH LINEAR MEASURE. 
1 milligram m.g. = .01543 grains. 
10 milligrams = 1 centigram, c.g. = .1543 grains. 
10 centigrams = 1 decigram, d.g. = 1.543 grains. 
10 decigrams = 1 gram, g. =15.43 grains. 
METRIC WEIGHT MEASURE. 
METRIC FLUID MEASURE. 
1 cubic centimeter, c.c. = 16.231 minims = .061028 cubic inches. 
1,000 c.c. = 1 liter, 1., — 33.815 fluid ounces = 61.028 cubic inches. 
1 c.c. of distilled water at 40 C. weighs 1 gram. 
METRIC LINEAR MEASURE. 
i millimeter, m.m. = .03937 inches. 
10 millimeters — x centimeter, c.m. = .3937 inches. 
10 centimeters = 1 decimeter, d.111. = 3.937 inches. 
10 decimeters — 1 meter, m. =39.37 inches. INDEX. 
PAGE 
Acetanilid 107 
Acetates, tests . . 102 
Acetic ether, preparation ....... 105 
Acid, acetic 102 
— albumin, preparation 125 
— arsenic 65 
— arsenous 65 
— bile 137 
— boric 45 
— butyric in 
— carbolic 108 
— carbonic 48 
— citric 104 
— fatty hi 
— hydrobromic 23 
— hydrochloric 20 
— hydrocyanic 49 
— hydrofluoric 26 
— hydroiodic 25 
— iodic 192 
— lactic 133, 142 
— muriatic 20 
— nitric 40 
— nitrous 39 
— nitro-hydrochloric 40 
— oxalic 103 
— picric 108 
— phosphoric 42 
— prussic 49 
— stearic 93 
— sulphuric 35 
— sulphurous 34 
— tartaric 104 
— uric 150 
— valerianic 103 
Acids, Analytical Table I 52 
II 53 
PAGE 
Acidimetry 83 
Acrylic aldehyde 112 
Albumins 122 
Albumin, acid 125 
— alkali 125 
Albumins, derived 125 
Albumin, egg 122 
— muscle 125 
— serum 139 
— in urine 155 
tests 155 
Albuminates, metallic 123 
Albuminoids 127 
Albumose 123 
Alcohol, absolute 99 
— preparation 99 
— tests 100 
Aldehyde, preparation 101 
— tests 102 
Alkali albumin 125 
Alkalimetry 84 
Alkaloids 184, 198 
— general reactions 187 
— solubility 187 
Aluminum, reactions 67 
Ammonia, albuminoid 87 
— free 87 
— preparation 38 
— tests 38 
Ammonium, reactions 74 
— sulphide 75 
Amyl acetate, preparation 105 
— nitrite, preparation 106 
Amylopsin, action 135 
Analytical Table I, acids 52 
II, acids 53 
Ill, metals 77 
201 202 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
PAGE 
Aniline colors 107 
— preparation 107 
Antidote, arsenic 168 
Antidotes, antimony 172 
Antimony, reactions . 63 
— rapid detection 172 
— sulphide 168 
— stains 173 
— separation 173 
— toxicology 171 
Antipyrin, tests 108 
Apomorphine, reactions 194 
Aqua Regia 40 
Arsenic, acid 65 
— agtidote 168 
— rapid detection 169 
— reactions 61 
— separation 170, 173 
— stains 169 
— toxicology 167 
— and antimony separation 173 
Arsenous acid 65 
— sulphide 168 
Atomic weights, table 199 
Atrophine, separation 195 
— tablet tests 195 
— reactions 194 
— toxicology 194 
Barium group 70 
— reactions 70 
Barley sugar, preparation 115 
Beer, test 100 
Benzene, preparation 106 
Benzoic acid, preparation 106 
Bile 136 
— acids 137 
— pigments 137 
— spectroscopical examination .... 138 
— pigments in urine 160 
Biuret reaction 121 
Bismuth nitrate, preparation 64 
— subnitrate, preparation 64 
— reactions 60 
Bleaching powder, preparation .... 71 
Blood 139 
— corpuscles 161 
— fats in 140 
PAGS 
Blood in urine 161 
— salts 140 
— stains, tests 141 
— spectroscopic examination 141 
Boiling point determination 93 
Bottger’s bismuth test 158 
Borax 45 
Borax bead . 45 
Boric acid, test 45 
Boron 45 
Bromine, preparation 23 
Bromides, tests 24 
British gum, preparation 115 
Brucine, detection 190 
— tests 190 
— toxicology 190 
Butter, preparation 143 
— soap, preparation 111 
— test 112 
Butyric acid, preparation in 
Cadmium sulphide 168 
Caffeine, extraction 184 
Calcium, reactions 71 
Calculi, urinary, table 164 
Calomel, preparation 65 
Cane sugar 115 
Caramel, preparation 115 
Carbolic acid, tests 108 
antidote 181 
detection 181 
toxicology 181 
Carbohydrates 113 
Carbon 46 
Carbonic acid, preparation 48 
Carbon dioxide, preparation 47 
— disulphide 49 
— monoxide, preparation 47 
— organic analysis 94 
Carbonates, test 49 
Casein, preparation 126,143 
Centrifuge 152, 153,156 
Chemical compound 9 
— change, evidences 10 
causes n 
Chlorates, test 21 
Chloral 98 
Chlorine, preparation 19 INDEX. 
203 
PAGE 
Chlorine water, preparation 20 
Chlorine, volumetric estimation .... 85 
Chloride of lime, preparation . ... 71 
Chlorides, formation 21 
— in water 86 
urine 151 
— test 21 
Chloroform, preparation 98 
— tests 98 
Cholesterine 136 
Chondrin 126 
Cinchona alkaloids 185 
— bark 185 
Citrates, tests 104 
Coagulated proteids . . 126 
Cocaine, general reactions 195 
— tests 196 
— toxicology 195 
Collodion, preparation 117 
Collogen 126 
Combustion furnace 95 
Copper, antidotes 178 
— group 60 
— rapid detection 179 
— reactions 60 
— separation 179 
— tests for sugar 157 
— toxicology 178 
Corn syrup, preparation 116 
Corpuscles, enumeration 141 
Corrosive sublimate 175 
Cream of tartar, preparation 74 
Crystallin preparation 124 
Cyanides, tests 50 
Decantation 7 
Delivery tube, construction 5 
Decinormal solution 83 
Derived albumins 125 
Desiccator 81 
Dextrine, preparation 115 
Dextrose 114 
Dialyzed iron 69 
Dialysis 7 
Diastalic estimation 128 
Diazo reaction 162 
Digestion, artificial gastric 131 
Distillation 7 
PAGB 
Distillation, destructive 47 
Donn&’s test 162 
Dropper, construction 5 
Elastin 126 
Electrolysis 8 
Emulsions 109 
Epsom salt 182 
Eclich’s diazo reaction 162 
Esbach’s albumin test 156 
Essence of mirbane, preparation .... 107 
Ether, preparation 101 
Etching 26 
Ethyl acetate, preparation 105 
— alcohol 94, 99 
— butyrate, preparation in 
Evaporation 6 
Ewald’s test 131,133 
Fats 109 
Fatty acids, preparation in 
Fat-splitting enzyme 135 
Fehling’s glycerine solution 158 
— quantitative solution 159 
test 159 
— test 114, 158 
Fermentation 99, 48 
— sugar test . 59 
Ferric acetate, preparation 69 
— chloride, preparation 68 
— hydroxide 168 
— salts, reactions .67 
— sulphate, preparation 68 
— tersulphate, preparation 68 
Ferro-cyanide, albumin test 156 
Ferrous chloride, preparation 68 
— iodide, preparation 68 
— salts, reactions 67 
— sulphate, preparation 68 
— sulphide, preparation 9 
Fibrin 126, 138 
Fibrinogen 125 
Fibrinoplastin, preparation .... 125, 140 
Filtration 7 
Flashing point, determination 97 
Fleitmann’s test 169 
Fluorescence, test 185 
Fluorine, preparation 26 
Formaline 102 204 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
PAGE 
Formulae, determination 95 
Fowler’s solution, preparation 65 
Fruit essences, preparation 106 
Fusing point, determination 93 
Gas, illuminating, preparation 47 
Gastric juice 130 
examination 131 
Gelatin 126 
Generator, construction 5 
Globulins, preparation 123 
Glucose, properties 114 
— in urine 157 
Glycerine, test 112 
Gmellin’s test 137 
Grape sugar . . 114 
Gravimetric analysis 81 
Group reagents 57 
Guiacum test 140, 161 
Gun cotton 117 
Gunpowder, preparation 40 
Giinzburg’s reagent 132 
— test 132 
Gypsum 72 
Hsematocrit 142 
Haemin 141 
Haemoglobin 139 
Hard soap no 
Heller’s albumin test 139, 155 
Hippuric acid 147 
Hydrobromic acid, preparation .... 23 
Hydroiodic acid, preparation 25 
Hydrochloric acid, preparation .... 20 
test 132 
Hydrocyanic acid 49 
Hydrogen dioxide, preparation .... 29 
test 29 
— preparation 17 
— sulphide, preparation 32 
reducing power 33 
Hypobromite, urea test 150 
Hypochlorites 71 
Hypophosphites 43 
Hyposulphites 36 
Ignition jet, construction 6 
Illuminating gas, preparation 47 
Insoluble soaps, preparation no 
Invert sugar, preparation 115 
PAGE 
Iodides, tests 25 
Iodine, preparation 25 
Iron, dialyzed, preparation 69 
— groups 66 
— (ic), reactions 67 
— (ous), reactions 66 
— reduced, preparation 69 
Irritant poisons 167 
Kerosene, test 97 
Labarraque’s solution 75 
Lactalbumin, tests 143 
Lactic acid, tests 133 
Lactometer 144 
Lactose 115, 143 
Lardacein 126 
Laughing gas, preparation 39 
Lead acetate 177 
— antidotes 177 
— plaster, preparation hi 
— reactions . 58 
— separation 178 
— toxicology 177 
Liebig condenser 87 
Lutein 137 
Magnesium, reactions 73 
Malt 116 
Maltose 115 
Malt sugar 115 
Marsh’s test 61, 170 
Mechanical mixture 9 
Mercury (ic) reactions 60 
— (ous) reactions 59 
— rapid detection 176 
— separation 176 
— toxicology 175 
Mercuric chloride, preparation 64 
— iodide, preparation 64 
— nitrate, preparation . 64 
Mercurous chloride, preparation .... 64 
— iodide, preparation 64 
— nitrate, preparation 64 
— oxide, preparation 64 
Metallic albuminates 123 
— groups 57 
— Irritants, Table V 197 
Metals, Analytical Table III 77 
Metatungstic acid 187 INDEX. 
205 
PAGE 
Oxalic acid, toxicology 182 
Oxides, preparation 30 
Oxygen, preparation 27, 28 
Oxyhaemoglobin 13, 139 
Ozone, preparation 28 
Ozonized ether 140 
Pancreatic extract 134 
—juice 134 
Paraglobulin. preparation 140 
Parchment paper, preparation 116 
Paris green, examination 169,179 
Pear oil, preparation 106 
Pepsin . . 130 
Peptones 123 
Pettenkofer’s test 137 
Phenol, tests 108, 181 
Phenylhydrazine, test 159 
Picric acid, preparation 108 
Pine apple flavor, preparation 112 
Phosphates, alkaline 152 
— earthy 43, 152 
— in urine 152 
— tests 43 
— triple 152 
Phosphoric acid, preparation 42 
Phosphorus, antidotes 180 
— detection 180 
— forms 42 
— toxicology 180 
Plaster paris, preparation 72 
Poisons, table for detection 196 
Polariscope 94, 160 
Potash, preparation 74 
Potassium formate 98 
— group 73 
— hydroxides, preparation 74 
— iodide •'.... 74 
— permanganate 74 
— reactions 73 
Precipitation 7 
Proteids, coagulated 126 
— reactions 121 
Protosulphate 68 
Prussic acid, preparation 49 
tests 5° 
Ptyalin 128 
Pus in urine 161 
PAGE 
Methane 46 
Methyl violet 102 
Milk, examination . 143 
— sugar 115 
Millon’s reaction 121 
— reagent 121 
Molecular weight, determination ... 96 
Morphine, detection 193 
— extraction 191 
— reactions 192 
— tablet tests 193 
— toxicology 191 
Mucin 126 
Mucus in urine 155 
Murexid test 151 
Muscle albumin, preparation .... 125 
Myosin, preparation 124 
Nesslerizing 87 
Nessler’s reagent 74 
Neutralization 30 
Neurotic poisons 184 
Nicotine, extraction 186 
Nitrates, tests 40 
Nitric acid, preparation 40 
— oxide .jg 
Nitrites, preparation 39 
— tests 39 
Nitrogen, organic analysis 94 
— preparation 37 
Nitro-benzene, preparation 106 
Nitro-hydrochloric acid, preparation . . 40 
Nitrous acid 39 
— ether, preparation 105 
— oxide, preparation 39 
Normal solution 82 
— urine constituents 147 
Nux vomica, tests 186 
Oleomargarine test 112 
Oils 109 
Oil of bitter almonds, preparation . . .107 
Opium, tests 191 
Optical activity 94 
Ossein 126 
Oxalates, tests 103 
Oxalic acid, antidotes 182 
detection 182 
preparation 103 206 
LABORATORY MANUAL OF MEDICAL CHEMISTRY. 
PAGE 
Quicklime 71 
Quinine, extraction 185 
— tests 185 
Rectified spirits 99 
Reduced iron, preparation 64 
Reducing solution . . ' 139 
Reduction 7 
— of units 4 
Red precipitate, preparation 64 
Reinsch’s test 62 
Rennin 131,135 
Rochelle salt 75 
Roger’s and Girdwood’s method .... 189 
Rose aniline, preparation 107 
Saccharomyces cerevisise 99 
Sal ammoniac 38 
Salicylic acid, test 133 
Saliva 127 
Saponification no 
Scale compounds, preparation 69 
Serum 139 
— albumin 139 
— globulin 140 
Silver groups 58 
— nitrate, standard solution 85 
— reactions .... . 58 
Soap, hard and soft no 
Soaps insoluble no 
Soda, preparation 75 
Sodium bicarbonate 75 
— hypochlorite 75 
— reactions 73 
Soft soap, preparation no 
Solids, total in water 86 
Soluble cotton, preparation . . . . 117 
Solution 6 
Specific gravity 148 
Spectroscope 137, 141, 161 
Standard solutions 82 
Stannous sulphide 168 
Starch, preparation .113 
Starch test paper 28 
Stearic acid 93 
Stirring rod, construction 5 
Stomach’s absorption 133 
— motility 133 
Strychnine, detection 189 
PAGE 
Strychnine, tablet tests 188 
— tests 188 
— toxicology . . 186 
Sucrose 115 
Sugars 115 
Sugar in urine 157 
— of lead 177 
Sulphanilic acid 162 
Sulphates in urine 153 
— tests 35 
Sulphides, metallic 33 
— tests 33 
Sulphites, tests 34 
Sulphur 32 
— organic analysis . . 95 
— dioxide, preparation 34 
Sulphuric acid, preparation 35 
Sulphurous acid 34 
Sweet spirits of nitre 105 
Symbols 199 
Syntonin, preparation 126 
Table I, acids 52 
— II, acids 53 
— Ill, metals 77 
— IV, calculi 164 
— V, poisons 197 
— of weights, atomic 199 
— of weights and measures 200 
Tartar emetic, preparation 65 
tests 172 
Tartrates, tests 104 
Temperatures, reduction ....... 4 
Test tube ... 6 
Thalleioquine test 186 
Theine, extraction 184 
Theobromine, extraction 185 
Thermometers 4 
Thiosulphates, tests 36 
Thistle tube, construction 6 
Toxicology 165 
Trommer’s test 157 
Trypsin 134 
Uffelman’s test 133 
Urates, acid and alkaline 150 
— tests 151 
Urea 149 
— estimation 150 INDEX. 
207 
PAGE 
Urea nitrate 149 
Ureameter 150 
Urinary calculi, table 164 
— constituents 147 
Uric acid, preparation 150 
Urine, albumin in 155 
— alkalies 148 
— bile pigments in 160 
— blood in 161 
— changes 148 
— color 147 
— constituents 147 
— chlorides in 151 
— diazo reaction of 162 
— glucose in 157 
— phosphates in 152 
— pus in 161 
— reaction 147 
— specific gravity 148 
— solids 149 
— sulphates in 153 
— total solids 149 
— urea in 149 
PAGE 
Urine, uric acid in 150 
Urinometer, correction 148 
Valencies 199 
Valerianic acid, preparation 103 
Vapor density, determination . . . . 96 
Verdigris, tests . 178 
Vinegar, mineral acids in 102 
Vitali’s tests 194, 196 
Vitellin, preparation 124 
Volatile poisons . . 197 
Volumetric analysis 82 
— solutions 82 
Water analysis 86 
— composition 29 
Weights, atomic 199 
— and measures, table 200 
Wood alcohol 94 
Wormley’s test 194 
Xanthroproteic reaction 121 
Yellow ammonium sulphide 75 
Yolk, egg, examination 124 
Zinc reactions 68