EMICAL EXPERIMENTS 
WARD 
SECOND EDITION 
Name HANDBOOK 
OF 
CHEMICAL EXPERIMENTS 
FOR 
DENTAL STUDENTS 
BY 
DeLANCEY W. WARD, Pii.D. 
WA- 
Professor of Physics, Chemistry and Metallurgy in the 
College of Dental and Oral Surgery 
of New York 
SECOND EDITION 
NEW YORK 
D. VAN NOSTRAND COMPANY 
25 Park Place 
1917 Copyright, 1916, 1917 
By DeLANCEY W. WARD 
PRESS OF 
BRAUNWORTH & CO. 
BOOK MANUFACTURERS 
BROOKLYN. N. Y. FOREWORD 
In compiling this laboratory handbook the author has 
merely put into book form the general order of instruction 
and experiments used in his laboratory for a number of years. 
His aim has been to lead the student to do as much theoretical 
and practical work by himself as possible. All questions 
asked should be answered, formulae inserted for all substances, 
and chemical equations worked out. 
The tests and analyses of biochemical products should be 
well studied and the work carefully performed so as to give 
a better understanding of certain tissues and fluids of the 
body. 
It is the sincere wish of the author that this laboratory 
guide may help in the broadening and deepening of chemical 
knowledge and tend to promote the student's appreciation 
of the importance of this subject in the study of dental 
medicine. 
De L. W. W. 
New York, December 1, 1916. 
PREFACE TO THE SECOND EDITION 
Happily on account of the exhaustion of the first, a sec- 
ond edition of this work was found necessary. Corrections, 
additional experiments and several new tests have been 
introduced to make the book more concise and to bring it 
to a higher standard of usefulness. 
De L. W. W. 
New York, November 21, 1917. 
III CHEMICAL EXPERIMENTS 
THE BUNSEN BURNER 
This is a special form of burner for producing heat without 
light and smoke, by the more complete combustion of illu- 
minating gas. Examine burner and briefly describe it. 
The gas and air mix in the lower part of the tube and burn 
at the top. As the gas and the air are intimately mixed 
combustion takes place in all parts of the flame. Now close 
the valve at the bottom and notice the luminous flame. 
Pass a toothpick slowly through this flame. Then open the 
air valve and notice the difference in the color of the flame; 
also pass a toothpick slowly through the flame. Explain 
why the flame is almost colorless at first, and yellow after- 
wards . (when the air valve is closed). What difference do 
you notice between the two toothpicks? Explain. There 
are various modifications of the Bunsen burner, but the prin- 
ciple is the same in all. 
WASH BOTTLE 
Examine the wash bottle and note each tube and its 
arrangement. When the wash bottle, filled with water, is 
inverted, the water will flow out of the tube with the larger 
opening. When the bottle is held in an upright position, 2 
and a current of air forced through the large tube by applying 
the lips and blowing, a fine jet of water will be forced out 
through the smaller tube. 
THE WORKING OF GLASS TUBES, RODS, ETC. 
The working of glass tubes, etc., into various forms, pieces 
of apparatus, and so forth, is treated in many books on ele- 
mentary chemistry, also in special works on glass blowing. 
It is generally sufficient to be able to cut a piece of tubing, to 
round the ends by holding in a flame until soft, closing one 
end of the tube and then blowing a bulb. Also bending 
and drawing out glass tubing and rods. 
In order to break off a piece of a glass rod or tube, make a 
small scratch with a triangular file. Then grasp the tube or 
rod with both hands, the thumbs extending along the tube 
and almost touching, and the scratch being on the opposite 
side. Now press gently with the thumbs and pull at the 
same time, when the tube will break at the mark. 
Before going further, the sharp edges of the tube or rod 
should be rounded, by holding the glass in the Bunsen flame, 
turning constantly, until the edges have melted and become 
round. 
If the above is continued, with a tube, the opening will 
become smaller and smaller and finally close. 
The closed tube can be used for making a bulb by heating 
about one-half an inch of the closed end of the tube and 
turning constantly. When quite hot and soft, remove from 
the flame, apply the lips to the open end and blow slowly, 
turning the tube all the time. The soft glass will expand 
and form a bulb. 
Tubes may be drawn out into points by placing the 3 
" wing top " on the burner (which gives a long, flat flame), 
and then holding the tube in the flame, and turning. When 
the tube is soft, pull slowly, turning at the same time, and 
the soft tube will be drawn out to a smaller diameter. 
If the same method of heating a tube is also used and 
when the tube is soft, it may be bent at any angle, the 
same as a piece of lead pipe. 
For further information consult Thomas Bolas, "Glass 
Flowing and Glass Working." 
SOME IMPORTANT OPERATIONS 
Solution. 
• The diffusion of a solid, liquid, or a gas, through a liquid. 
It may be either mechanical, physical, or chemical. 
Sedimentation. 
' The separation of a mixture of a finely divided solid and 
a liquid by letting it stand and allowing the solid to fall 
to the bottom of the vessel by gravity, e.g., muddy water. 
Decantation. 
The pouring off or syphoning of a clear liquid after sedi- 
mentation. 
Filtration. 
The separation of a mixture of a solid and a liquid (muddy 
water) by means of a porous substance or filter, upon which 
the mixture is usually poured. The liquid (filtrate) passes 
through, but the solid (residue) is retained on the filter. 4 
Glass funnels with discs of paper made into cones and 
placed in the funnel are generally used in chemical opera- 
tions. 
Question: Can you explain why the angle of the funnel 
should be 6o°? 
Precipitation. 
The separating out of a substance, in the solid form, from 
a solution. It may be either physical or chemical. The 
former when the solution changes, as the separation of a 
resin from an alcoholic solution, by the addition of water. 
The latter, the formation of a new substance, insoluble in the 
solvent, by changing the composition of the substance in 
solution, as washing soda added to lime water, forming cal- 
cium carbonate which is insoluble. 
Evaporation. 
The separation of a liquid from a solid, either in sus- 
pension or solution, by converting the liquid into vapor and 
allowing it to escape. 
Distillation. 
It is the same as evaporation except that the vapor 
is not allowed to escape, but is condensed by cooling, and 
collected. 
Sublimation. 
The vaporization of a solid and its condensation back to 
the solid state. 5 
Solubility. 
(Unless the solvent is mentioned, water is used.) 
The solubility of a substance may be determined by plac- 
ing a small amount in a test tube, adding distilled water and 
shaking. If the solid disappears it is soluble. It may be 
only partially or slightly soluble and appear not to dissolve. 
In that case filter off the solution and evaporate the filtrate 
in a porcelain dish. If the substance was soluble there will 
be a residue left in the dish. 
GENERAL EXAMINATION OF SUBSTANCES 
As many students, in beginning the study of chemistry, 
and the examination of the different forms of matter, are at 
a loss as to the method of procedure, the scheme given below 
was introduced into my laboratory a nunber of years ago. 
This scheme should be followed for each substance and 
answers given on the blank pages. 
Solids. 
Color: 
Odor: 
Crystalline or amorphous, examine particles under micro- 
scope; if crystalline, draw some crystals. 
Hardness: 
Scratched with the nail-soft. 
Scratched with a file-hard. 
Not scratched with a file-very hard. 
Melting-point: 
Specific gravity: 
Solubility: 6 
Magnetic: usually for metals only. 
Action of heat: Charring indicates a carbon compound. 
Combustible: 
Liquids. 
Color: 
Odor: 
Viscosity: 
Specific gravity: 
Boiling-point: 
Action on litmus paper: 
Blue becomes red =acid action 
Red becomes blue = alkaline action 
Neither affected = neutral 
Both slightly = amphoteric 
Combustible: 
Is it a solution or a simple liquid? Evaporate some and 
look for a residue. 
Gases. 
As gases tend to escape, unless confined, it is necessary 
to keep them in closed vessels, and also to prevent their 
mixing with the air. They also require special methods for 
collection, depending upon the nature of the gas. 
If heavier than air they may be collected by downward 
displacement, that is, by allowing them to flow into an up- 
right bottle and displace the air (like a liquid). If lighter 
than air the bottle is inverted, and the gas, rising in the bottle, 
pushes out the air (upward displacement). Gases may also 
be collected over water (the method most commonly used), 
which is employed when the gas is only slightly soluble in 7 
water or not affected chemically by it. The bottle is filled 
with water, a glass plate placed on the mouth, and pressed 
down with the finger. This system is then inverted and the 
neck of the bottle carried below the surface of the water 
contained in a pan or vessel called a pneumatic trough. The 
plate is then removed, the water remaining in the bottle 
The gas is then allowed to enter at the mouth of the bottle, 
and rising displaces the water. When the bottle is full, 
the glass plate is again placed on the mouth and the system 
removed from the trough. In some cases water cannot 
be used, and then a mercury trough is substituted. 
Color: 
Odor: 
Taste: 
Specific gravity. Whether it is lighter or heavier than 
air is usually sufficient. 
Solubility: 
Remove the cover a little, pour some water into the 
bottle (about one inch), replace the cover, and shake. The 
force required to remove the cover, will give some idea of 
the quantity of gas dissolved, as the pressure will be pro- 
portional to the solubility of the gas. 
Action on litmus paper: Dry gases do not act upon dry 
litmus, the paper must be moistened with water before 
making the test. 
Is it combustible? 
Does it support combustion (like air)? 
Is it indifferent, neither burns nor supports combustion? 8 
THE STUDY OF CHEMICAL CHANGES 
(1) Analytic (separation). The separation of a substance 
into simpler forms of matter (compounds or elements). 
(a) Examine the substance given: 
Condition: crystalline or amorphous. 
Color: 
Solubility: 
Heat some in a glass bulb, with tube bent in form of a 
V. Is a gas given off? Test with flame, test with spark 
on end of a toothpick. Does anything collect in the "V" 
part of the tube? If so, remove, and see if you can iden- 
tify it. 
Is the change chemical? Give reasons. 
(5) Examine limestone or chalk: • 
Color: 
Solubility: 
Action on litmus paper: 
Heat some in a small, hard glass tube, and test for gases 
Examine the residue in the tube. Has it changed in ap- 
pearance? Does it dissolve in water? Has it any action 
on litmus? Is there a chemical change? Give reasons. 
(2) Synthetic (putting together). 
Examine iron filings. 
Examine flowers of sulphur. 
Prepare a mixture of the two in about equal parts, rub 
well together and answer the following: 
1. Are the iron and sulphur separate? Use microscope. 
2. Will a magnet separate the iron from the sulphur? 
3. Will carbon tetrachloride dissolve one and leave the 
other? 9 
4- Will hydrochloric acid dissolve one and leave the 
other? Which? If a gas is given off, notice the odor. 
5. Heat some of the mixture in a small test tube. Does 
it glow? 
Then cool, remove the mass from the tube and examine: 
1. Microscope. 
2. Magnet. 
3. Carbon tetrachloride. 
4. Hydrochloric acid, and see if the gas given off has 
the same odor as before. 
Draw conclusion, as to a chemical change. 
Other chemical changes. 
(a) Examine a piece of zinc, then place it in a large test 
tube containing about two inches of hydrochloric acid dilute. 
Is a gas given off? If so, test. 
When all the zinc has disappeared filter the solution, 
if necessary, and evaporate the filtrate in a porcelain dish. 
Examine the residue, and give reasons for thinking a 
chemical change has taken place. 
Allow the dry residue to stand until the next period. 
What change to you observe? 
(Z>) Examine some crystals of copper sulphate. Heat 
some in a tube. What do you observe? 
Dissolve some of the crystals in water, note color of the 
solution. 
Place a piece of clean iron into the solution, warm, and 
answer the following: 
Does the solution change in color? 
Remove some of the red substance formed. Dry and 
rub with a knife blade. Can you identify it? 
Explain the changes. 10 
PREPARATION AND PROPERTIES OF OXYGEN 
Required: 
Hard glass tube, side-neck, and cork. 
Wash bottle for gas. 
Tin pan, glass bottles and flat covers for collecting gas 
over water. Oxygen mixture (potassium chlorate two parts, 
and manganese dioxide one part). 
Sodium hydroxide solution for wash bottle. 
Set up apparatus, as shown on the demonstrating table, 
heat the oxygen mixture and when the gas appears at the 
delivery tube, collect four bottles and make the following 
tests: 
(1) With one bottle: 
Color: 
Odor: 
Solubility: 
Action on litmus: 
(2) In another bottle burn some wood, add water, shake 
and test with litmus paper. 
(3) Burn sulphur in another and test as in (2). 
(4) Burn magnesium ribbon in another and test as in (2). 
What are your conclusions in regard to combustion in 
oxygen?- Is it an acid-forming element? 
FLAME TESTS 
Some substances, when heated in the clear Bunsen flame, 
will impart a color which is characteristic for that substance 
and serves for its identification. These tests are made by 
heating the substance on a clean platinum wire, as follows: 11 
Clean the platinum wire by dipping it into concentrated 
hydrochloric acid and holding it in the flame, until all color 
has disappeared. Then, without touching the wire, dip it 
into the substance to be tested and hold in the flame again; 
note color imparted. If to the substance (being a solid) 
a small amount of pure hydrochloric acid concentrated, is 
added, better results will be obtained, as the chlorides formed 
are very volatile. 
Report the following substances, cleaning the wire before 
each test: 
Potassium chloride. 
Calcium chloride. 
Lithium chloride. 
Barium chloride. 
Strontium chloride. 
Sodium chloride. 
PREPARATION AND PROPERTIES OF HYDROGEN 
Place a piece of zinc in a large test tube, add about two 
inches of dilute sulphuric acid and test the gas evolved: 
Color: 
Odor. (May be an odor from impure zinc.) 
Action on litmus paper. 
Place a large test tube, mouth downward, over the first 
and let it remain there for a few minutes, then remove, keep- 
ing the mouth downwards, and introduce a flaming tooth- 
pick. 
Does the gas support combustion? 
What is formed when it burns? 
Is the gas lighter than air? 12 
Give reasons for your answers. 
Hydrogen is the essential element of all acids, but hydro- 
gen ions only give an acid action; the element is neutral. 
ACID TESTS 
These are made for the part or radicle associated with 
the hydrogen and are called anions; hydrogen gives cations. 
Test for chlorine ions (colorless). 
Make the solution slightly acid with dilute nitric acid, 
then add a few drops of silver nitrate solution. A white, 
curdy precipitate is formed, which blackens in the light, 
and is soluble in ammonium hydroxide. 
Test for sulphuric ions. 
Make the solution slightly acid with dilute hydrochloric 
acid and add a few drops of barium chloride solution, a heavy, 
white precipitate of barium sulphate is formed. Other acid 
tests will be given later. 
PREPARATION AND PROPERTIES OF HYDROGEN 
DIOXIDE 
Put about 20 c.c. of dilute sulphuric acid into a small 
beaker, place on a wire gauze on the ring stand. Add, in 
small portions at a time, io grams of powdered barium dioxide 
and stir well. Heat the mixture carefully for fifteen minutes, 
adding water from time to time to keep up the volume. 
Then add barium carbonate slowly with stirring until there 
is no further effervescence, showing that excess of sulphuric 
acid has been neutralized. Heat for a short time, filter off 
the barium sulphate, cool the filtrate and test with potassium 13 
iodide starch mixture. A blue coloring of the starch indi- 
cates hydrogen peroxide. 
Make the following tests: 
(1) Add some dilute chromic acid solution to hydrogen 
peroxide. What is the color produced? It is due to the 
perchromic acid formed. 
(2) Add some hydrogen peroxide to a dilute solution of 
potassium permanganate. Observe change and explain the 
reaction. 
EXAMINATION OF THE HALOGENS 
Fluorine. 
This element has been prepared only with great difficulty, 
so will not be studied in the laboratory, but its hydrogen 
compound can be easily prepared. 
Hydrofluoric Acid. 
(1) Place some calcium fluoride in a leaden dish and add 
concentrated sulphuric acid sufficient to cover the powder. 
Place on a ring stand and heat with a small flame. Cover 
the convex side of a watch glass with paraffine, by warming 
the glass and rubbing a piece of paraffine over the surface. 
When cool make some marks with a hard instrument on the 
paraffine so as to expose the glass. Place the glass, convex 
side down, on the lead dish and let it remain for half an hour. 
Then take off the watch glass, and remove the paraffine by 
warming and rubbing with a towel. Explain the phenom- 
enon observed, and write the equations. 
(2) Clean a microscopic slide and make some tracings 14 
with hydrofluoric acid solution. Allow to stand for ten 
minutes, wash off with water and explain the phenomenon. 
Chlorine. 
Place about half an inch of manganese dioxide in a large 
test tube, add about io c.c. of hydrochloric acid cone., heat 
carefully, and examine the gas evolved. 
Color: 
Odor: 
Light or heavy: Can the gas be poured from one tube 
to another? 
Solubility: allow the gas to come in contact with some 
water in another tube, and shake well. 
Action on litmus paper: 
Does it burn? 
Does it support combustion? 
Try action on a piece of dyed cotton cloth: the cloth 
must be wet. Why? 
Introduce some bleaching powder into a large test tube, 
add some sulphuric acid dilute; warm and try the action on 
litmus paper, first dry, then wet. 
Preparation and Properties of Hydrochloric Acid Gas 
Place some sodium chloride in a large test tube, fitted 
with rubber stopper and doubly bent tube. Add sufficient 
concentrated sulphuric acid to cover the salt completely, 
insert the stopper and heat carefully. Write the equation. 
Test with litmus paper, first dry, then wet. Pass the 
gas into some distilled water, is it soluble? 
Test the solution for: 15 
Hydrogen ions; and chlorine ions, as usual. 
Do you think it is a strong acid? Give reasons. 
Aqua Regia. 
A mixture of hydrochloric and nitric acids, which gives 
off chlorine. Why? Write the equation. 
Try the action on a piece of gold foil and explain. 
Bromine. 
Prepare a mixture of potassium bromide and manganese 
dioxide. 
Place in a large test tube and add some dilute sulphuric 
acid. Hold the tube in a slanting position and observe: 
Is a gas or a liquid evolved? 
Color. 
Odor. 
Light or heavy? 
Is it soluble? 
Add a few drops of dilute hydrochloric acid to a bromide 
solution and about i c.c. of carbon tetrachloride, which will 
fall to the bottom of the tube. Then some chlorine water, 
shake, let stand and observe that the globule at the bottom 
of the tube is colored yellow or yellow-red, due to the solu- 
tion of the bromine. 
Add more chlorine water and see if the color is bleached. 
Iodine. 
Condition: 
Form: 
Color: 
Odor: 16 
Solubility in: 
Water. 
Alcohol. 
Carbon tetrachloride. 
Note colors of the last two solutions. Can you explain 
the difference? 
Iodine is soluble in a solution of potassium iodide. 
The tincture contains potassium iodide. Why? 
Heat some iodine in a small test tube held almost hori- 
zontal and observe. 
Does it melt? 
Does it vaporize without melting (sublime)? 
What is the color of the vapor? 
Does the vapor condense to a liquid or a solid? 
Test for Free Iodine. 
Add one drop of Lugol's solution * to some dilute starch 
paste in a test tube, shake and note color. 
Heat the tube and note what happens. 
Allow to cool and note again. 
Can you explain the changes? 
Test for Iodine Ions. 
This test is made in the same manner as that for bromine 
(see page 15). 
Add more chlorine water and see if the color disappears. 
Iodine and bromine ions precipitate silver nitrate solu- 
tion as well as chlorine ions, giving silver iodide and bromide, 
respectively. All are affected by light. (Photography.) 
* A solution of potassium iodide and iodine in water. 17 
NITROGEN 
Preparation: by burning out the oxygen from air. 
Tall, graduated bell jar, open at the top; deflagrating 
spoon for burning phosphorus and rubber stopper; also a 
deep, wide glass jar or pneumatic trough, containing some 
water. 
Place the bell jar partly in the water, read the volume of 
air, and, without changing the level of the water, intro- 
duce the deflagrating spoon with some burning phosphorus, 
also inserting the rubber stopper. Lower the jar somewhat 
to prevent the escape of any air and when the combustion 
ceases allow the gas to cool and the white vapor to be ab- 
sorbed by the water. Then raise or lower the jar until the 
level of the water is the same within and without and read 
the volume of the gas. Why should the water levels be made 
the same? 
Determine the per cent of this gas in air? 
Does it burn? 
Does it support combustion? 
Has it any effect on lime water? 
It is not pure nitrogen, but contains about i per cent 
of argon and small quantities of rare gases. 
PREPARATION AND PROPERTIES OF NITRIC 
ACID 
Set up a glass-stoppered retort and receiver, shown on 
the demonstrating table. The retort supported on a wire 
gauze and held by a clamp. All the glass apparatus should 
be dry. 18 
Introduce some sodium nitrate into the retort, and add 
enough concentrated sulphuric acid to cover it. Heat care- 
fully and distil off the nitric acid. Make the following tests: 
Color: 
Odor: 
Solubility: 
Taste. Place one drop in a test tube half full of water, 
mix and taste. 
Action on litmus paper. 
Action on copper: write the equation. 
Action on tin: and state if it differs from that of copper. 
Action on wool: Place a small mass of worsted in the neck 
of a test tube containing about half an inch of concentrated 
nitric acid. Heat, record phenomena. 
Action on turpentine, an inflammable substance. Place 
some nitric acid in a test tube, standing in the rack, then 
add some turpentine, a few drops at a time, by means of a 
long glass tube. (Do not stand near the test tube.) Note 
phenomena and explain. 
Test for nitric ions. 
Add a crystal of ferrous sulphate to the solution, then 
allow concentrated sulphuric acid to flow down the side 
of the tube slowly and collect in the bottom, where the two 
liquids meet, a brown ring will appear. 
PREPARATION AND PROPERTIES OF AMMONIA 
Heat a mixture of an ammonium salt, with calcium 
hydroxide in a large test tube, and examine the gas evolved. 
Odor: (Smell carefully.) 
Color: 
Action on wet, red litmus paper: (Why wet?) 19 
Moisten a glass rod with concentrated hydrochloric acid, 
and hold in the gas; what do you observe? Explain. 
Pass some of the gas into water and test the water. What 
is formed? and why does the water become alkaline? 
Test for ammonium, either as a solid or in solution 
(ammonium ions). Place some of the substance in a large 
test tube, add about one inch of caustic potash solution, 
heat and test gas with wet, red litmus paper. The paper 
will become blue. 
Nessler's Test. 
Nessler's solution * added to a colorless solution of an 
ammonium compound will give a yellow color or precipi- 
tate, depending upon the amount present. This is a very 
delicate test. Use a weak solution, (i : 100.000.) 
PREPARATION AND PROPERTIES OF NITRIC 
OXIDE 
Prepare a gas generator consisting of a wide-mouthed 
bottle, rubber stopper with two holes, funnel and delivery 
tube, pneumatic trough, bottles and plates. 
Place some copper in the generator with sufficient water 
to cover it. Then pour concentrated nitric acid through 
the funnel tube until there is a brisk evolution of gas. Col- 
lect three bottles; the gas should be colorless. The orange 
fumes appearing in the generator are nitrogen dioxide and 
are dissolved by the water. 
Open one bottle of gas and notice change of color. Explain. 
Try the combustion of sulphur. 
Try the combustion of phosphorus. Explain the difference. 
* A solution of mercuric iodide in potassium iodide, and made alkaline 
with caustic soda. 20 
PREPARATION AND PROPERTIES OF NITROUS 
OXIDE 
Set up apparatus, as shown, on the demonstrating table. 
Hard glass tube, with side neck and a cork. The tube sup- 
ported in a clamp, and the side neck joined to two wash bot- 
tles. The first contains a Solution of ferrous sulphate; the 
second a solution of caustic soda. The delivery tube extends 
into warm water in the pneumatic trough. Place some 
ammonium nitrate in the hard glass tube. Insert the cork 
into the neck and heat carefully. When the salt is melted 
and appears to begin to boil, test the gas evolved at the 
delivery tube with a spark on the end of a toothpick. When 
the spark is in flame, collect six bottles of the gas. Remove 
the cork from the hard tube before taking away the flame, 
to prevent back suction of the ferrous sulphate solution, 
causing an explosion. 
Examine the gas: 
Color. 
Odor. 
Taste. 
Solubility. 
Action on litmus paper. 
Does it burn? 
Burn wood and test. 
Burn sulphur and test. 
Burn magnesium and test. 
How distinguished from oxygen? 
Do you think it would support life? 
Test the ammonium n'trate for: 
(a) Ammonium group. 
(Z>) Nitrate group. 21 
EXAMINATION OF CARBON 
Heat a piece of wood charcoal on the wire gauze with the 
Bunsen flame, and explain the change. 
Carbon is always obtained when organic matter (plant 
or animal), is heated in closed vessels or out of contact with 
oxygen. The products formed are gases and liquids. 
Destructive distillation. Heat a piece of wood in a large 
test tube, held almost horizontal. Explain changes and iden- 
tify products formed as far as possible. 
PREPARATION AND PROPERTIES OF CARBON 
DIOXIDE 
Prepare a gas generator, consisting of a wide mouth bottle, 
rubber stopper with two holes, funnel tube, delivery tube, 
pneumatic trough and bottles for collecting the gas. 
Introduce some limestone into the generator, with some 
water to cover it. Then add enough hydrochloric acid to 
start a brisk effervescence. Test for the gas at the delivery 
tube with a spark on the end of a toothpick. When the 
spark is extinguished collect the gas. 
Then make the following tests: 
(1) Collect a bottle of gas by downward displacement 
(dry gas), and test with blue litmus paper, first dry then wet; 
note difference and explain. 
(2) Burn some magnesium ribbon in a bottle of the 
gas; can you explain the combustion? 
(3) Add some lime water to a bottle of the gas, shake and 
explain. 
(4) Pass the gas into lime water, note action as in (3), 22 
continue to pass in the gas until clear. Can you explain 
the change? 
Divide the solution from (4) into two parts: 
(5) To one portion add some tincture of soap solution, 
shake and explain. 
(6) Boil the other portion and explain. 
(7) Filter the mixture obtained from (6), add soap solu- 
tion, shake and explain the difference between (5) and (7). 
(8) Breathe into lime water contained in a large test 
tube. What do you observe? Explain. 
Carbon dioxide is formed in all cases where carbon is 
oxidized by excess of oxygen. 
PREPARATION AND PROPERTIES OF CARBON 
MONOXIDE * 
This gas is formed by the reduction of carbon dioxide, 
also by the decomposition of certain carbon compounds. 
Heat oxalic acid with concentrated sulphuric acid in a 
flask and pass the gases evolved through a solution of caustic 
soda to remove the carbon dioxide, also formed. Collect 
the gas over water. 
Test its properties as usual. 
Burn some in a bottle with the mouth upward, and 
test with lime water. Explain. 
METHANE (MARSH GAS) 
Heat a mixture of soda-lime and dry sodium acetate 
in a large test tube, collect the gas over water and test: 
Color. 
Odor. 
* This gas is very poisonous, so do not inhale any. 23 
Light or heavy? 
Solubility. 
Action on litmus. 
Does it burn? 
Does it support combustion? 
Burn some and test products with lime water. 
ACETYLENE 
Pour about io c.c. of water into a large test tube, and 
add two or three small pieces of calcium carbide; notice 
the effervescence. 
Test the gas: 
Color. 
Odor. 
Light or heavy? 
Action on litmus. 
Does it support combustion? 
Burn gas and notice the character of the flame, test the 
products of combustion with lime water. 
CYANOGEN * 
Place some mercuric cyanide in a test tube, fitted with 
a cork and a jet tube. Heat in the Bunsen flame, and note 
the burning gas. 
Explain the color of the flame and products of combus- 
tion. 
* This gas is exceedingly poisonous, so do not inhale any. 24 
CHLOROFORM 
Make a mixture of bleaching powder and calcium hy- 
droxide, place in a large test tube; and pour in a mixture of 
io c.c. of ethyl alcohol and 20 c.c. of water, heat carefully 
for several minutes, and note the odor of chloroform. 
Obtain some chloroform and note the following: 
Color. 
Odor. 
Taste. 
Light or heavy? 
Solubility. 
Action on litmus. 
Is it inflammable? 
Solubility of gutta percha? 
Compare with ethyl ether. 
CARBON TETRACHLORIDE 
Examine this compound for: 
Color. 
Odor. 
Combustibility. 
Solvent action on rubber. 
Solvent action on sulphur. 
IODOFORM 
Warm a mixture of potassium carbonate and ethyl alco- 
hol; then add in small portions at a time, some crystals of 
iodine. When ah the iodine has been added, heat ten minutes 25 
longer and set aside to cool; them remove crystals and 
examine. 
Condition. 
Color. 
Odor. 
Solubility in: 
(a) Water. 
(7>) Alcohol. 
ETHYL ALCOHOL 
Prepare a 5 per cent solution of glucose in water, about 
100 c.c. Make neutral with sodium carbonate, add a small 
piece of Fleischmann's yeast. Introduce the mixture into 
a flask, fitted with a rubber stopper and a doubly bent tube, 
one end of which is inserted into the rubber stopper, the other 
dipped below the surface of some lime water, contained 
in a large test tube. Allow the system to stand in the desk 
until next time. 
What change has taken placein the lime water? 
Notice the odor of the mixture. 
Remove the tube from the lime water, place the flask 
on a wire gauze, heat the contents to boiling, distil off about 
10 to 15 c.c. and examine. 
Color. 
Odor. 
Taste. 
Iodoform test. Heat some of the distillate with a small 
amount of potassium carbonate, add a few crystals of iodine, 
warm for a few minutes and note the characteristic odor of 
iodoform. 26 
ETHYL ETHER 
Condition. 
Color. 
Odor. 
Taste. 
Light or heavy? 
Solubility. 
Action on litmus. 
Combustibility. Place a small amount in a porcelain 
dish, apply a flame (do not stand close to the dish). 
Compare with chloroform. 
FORMALDEHYDE 
Place 5 c.c. of methyl alcohol in a large test tube, held 
in the test tube holder. 
Heat a piece of copper gauze in the upper part of the 
Bunsen flame, to oxidize it. Partly cool and drop it 
into the methyl alcohol. Notice the color of the copper 
gauze, before it enters the alcohol and after. Remove gauze 
allow any sediment to settle and examine the solution: 
Color. 
Odor. 
Action on ammonio-silver nitrate solution. 
Schiff's Test. 
Make a o.i per cent solution of fuchsin and treat with 
sulphur dioxide until colorless. On the addition of for- 
maldehyde a violet color will appear. 27 
SULPHUR 
Examine some crystals of sulphur under the microscope, 
draw some and see if you can determine the crystalline 
form and system. 
Is it soluble in water? 
Is it soluble in carbon disulphide? 
What is formed when it burns in air? 
PREPARATION AND PROPERTIES OF SULPHUR 
DIOXIDE 
Place some sodium sulphite in a large test tube, fitted with 
rubber stopper and bent delivery tube, add some hydrochloric 
acid and collect the gas by a downward displacement. 
Color. 
Odor. 
Action on litmus, first dry, then wet. 
Solubility. 
Does it burn? 
Try action on some weak fuchsin solution and explain. 
SULPHURIC ACID 
Bring two bottles together mouth to mouth; the one 
above containing sulphur dioxide, the one below nitrogen 
dioxide, allow them to stand and observe changes. Later, 
add a small amount of water to each, shake, mix and test 
for: (a) Hydrogen ions, (&) sulphuric ions. Write all the 
equations. 28 
It may be prepared in a small way for tests, by the fol- 
lowing method.* 
Heat a mixture of sulphur with about twice its weight 
of potassium chlorate in a large test tube, use a test tube 
holder. Explain the phenomenon (deflagration). Let the 
tube cool, add some distilled water, shake and let stand until 
liquid is clear. Pour off the clear liquid and test. 
(1) For hydrogen ions. 
(2) For sulphuric ions. 
Write all the equations. 
Examine some of the su'phuric acid in the bottle on 
the desk for 
Color. 
Odor. 
Viscosity (limpid or oily). 
Pour some into cold water very carefully. Note effect 
and explain.! 
Try the action on: 
(1) Zinc; first dilute, then concentrated. 
(2) Copper; first dilute, then concentrated, with heat. 
(3) Sugar; place some sugar in a large test tube, sup- 
ported in a holder, then add some concentrated sulphuric 
acid carefully. 
(4) Wool; make test the same as (3). Explain each 
action. 
(5) Place a part of a tooth in 50 per cent sulphuric acid; 
examine from time to time and explain the effect. (Callahan.) 
* This laboratory method of preparing sulphuric acid was first suggested 
to me a number of years ago by Prof. H. T. VultS, Teachers College, Co- 
lumbia University. 
f When mixing the acid with water the above order should be used to 
avoid serious accidents, which are not uncommon. 29 
PREPARATION AND PROPERTIES OF HYDROGEN 
SULPHIDE 
Arrange a large test tube with rubber stopper and bent 
glass tube as in other experiments for the preparation of 
gases. Introduce some pieces of ferrous sulphide into the 
tube and add enough dilute hydrochloric acid to cover them. 
Observe the effervescence. Examine the gas: 
Color. 
Odor. 
Solubility. 
Action on litmus paper. 
Does it burn? 
Does it support combustion? 
Test with lead paper.* 
Action on a silver coin (so-called oxidized silver). Explain. 
TESTS FOR SOME OF THE HEAVY METALS 
(CATIONS) WITH HYDROGEN SULPHIDE 
Treat solutions of the following metals with hydrogen 
sulphide, note the effect on each, and write the equation. 
Zinc. 
Precipitated by hydrogen sulphide in alkaline or acetic 
acid solution as zinc sulphide; white precipitate soluble in 
dilute mineral acids. 
* Made by moistening a piece of filter paper with lead acetate solution. 30 
Lead. 
Precipitated by hydrogen sulphide in acid solution as lead 
sulphide, black precipitate, insoluble in dilute acids, is con- 
verted into lead sulphate (white), by the action of hydrogen 
peroxide. 
Copper. 
Precipitated by hydrogen sulphide in acid solution as 
copper sulphide, blue black precipitate soluble in nitric acid 
(distinction from mercuric sulphide). 
Cadmium. 
Precipitated by hydrogen sulphide in acid solution as 
cadmium sulphide, bright yellow precipitate soluble in nitric 
acid, insoluble in ammonium sulphide (distinction from 
arsenic sesquisulphide). 
Bismuth. 
Precipitated by hydrogen sulphide in acid solution as 
bismuth sulphide, black precipitate, soluble in nitric acid 
(distinction from mercuric sulphide). 
Tin. 
(May be stannous or tannic.) 
Both precipitated by hydrogen sulphide in acid solution, 
stannous sulphide, brown precipitate; stannic sulphide, 
yellow precipitate. Both soluble in ammonium sulphide. 
Mercury. 
(May be mercurous or mercuric). 
Mercurous: Precipitated by hydrogen sulphide as mer- 31 
curous sulphide, mixed with mercury, black precipitate, 
insoluble in ammonium sulphide; soluble in aqua regia. 
Mercuric: Precipitated by hydrogen sulphide, in acid 
solution as mercuric sulphide, black precipitate, insoluble 
in ammonium sulphide, and dilute nitric acid; soluble in 
aqua regia. 
Silver. 
Precipitated by hydrogen sulphide as silver sulphide, 
black precipitate, soluble in hot nitric acid. 
Gold. 
. Precipitated by hydrogen sulphide in acid solution as 
gold sulphide, insoluble in acids, soluble in aqua regia, and 
in ammonium sulphide. 
EXAMINATION OF CARBON DISULPHIDE 
Condition: 
Color: 
Odor: 
Light or heavy? 
Solubility: 
Is it inflammable? 
Solvent action on: 
(1) Sulphur. 
(2) Rubber. 
How would you distinguish this compound from: 
(а) Carbon tetrachloride? 
(б) Chloroform? 32 
SILICON 
Silicic Acid. 
Dissolve some sodium silicate in water, filtering the 
solution if necessary. 
Observe character of the solution. 
Test with litmus paper, and explain the result. 
To the solution add some dilute hydrochloric acid. 
What change do you observe? 
Is it still a solution? 
Is it a hydrogele? 
Can it be filtered? 
Can it be dialysed? 
BORON 
Boric Acid. 
Condition: 
Color: 
Odor: 
Taste: 
Solubility: 
Action on litmus paper: 
Is it a strong or weak acid? 
Make flame test. 
Borax. 
Color: 
Odor: 
Taste: 
Solubility: 
Action on litmus paper: 33 
Borax gives a yellow flame due to the sodium present. 
Heat a mixture of borax and concentrated sulphuric acid. 
Add alcohol, set on fire and note color of flame. 
Bead tests. 
Make a bead in the loop on the end of the platinum wire, 
by heating wire and dipping it into the borax and heating 
again. The bead should be clear and colorless. 
Now heat bead and dip it into some cupric oxide; heat 
again and note color. What is formed? 
Make separate bead tests for the following in the same 
way and report, color of each, while hot as well as cold. 
Cobalt oxide. 
Nickel oxide. 
Ferric oxide. 
Manganese oxide. 
Chromium sesquioxide. 
Borax is called an acid flux. Why? 
PHOSPHORUS 
Compare the properties of red and yellow * phosphorus. 
Condition: 
Color: 
Odor: 
Combustibility with slight heat? 
What is formed when yellow phosphorus is exposed to the 
air? 
What is formed when they burn? 
* Keep yellow phosphorus under water until wanted. Do not handle it. 34 
Ortho Phosphoric Ions. 
The addition of ammonium molybdate to an orthophos- 
phate solution, will give a yellow crystalline precipitate. 
Silicic and ortho arsenic acids give the same colored 
precipitate only after heating. 
Examine Meta or Glacial Phosphoric Acid. 
Condition: 
Color: 
Odor: 
Solubility: 
Action on litmus. 
Taste. (Use a dilute solution.) 
Use a fresh solution for tests. 
Compare Solutions of Each Acid. 
Meta. Orth. 
Action on albumen solution. 
Action on silver nitrate solution. 
Action on barium chloride solution. 
Prepare a dental cement by mixing some phosphoric 
acid solution with zinc oxide. What is formed? 
EXAMINATION OF ARSENIC * 
Condition: 
Crystalline form: 
Color: 
Is it lustrous? 
* Great care must be taken not to breathe any fumes evolved in these 
experiments, as they are very poisonous. 35 
Is it soft or brittle? 
Heat some, mixed with charcoal to prevent oxidation, in 
a large test tube, held in a horizontal position. 
Examine crystals. 
Heat some, as above, mixed with potassium nitrate, to 
oxidize it. 
Does it sublime? Examine the crystals. 
What is their color? 
Remove some of the crystals, dissolve in water and 
test with litmus paper. What is formed? 
EXAMINATION OF ARSENIOUS OXIDE* 
It is sometimes called arsenious acid. Is it an acid? 
Condition: 
Color: 
Odor: 
Solubility: 
Heat some and notice odor: 
(1) Add some hydrogen sulphide to a solution made 
slightly acid with hydrochloric acid. What do you observe? 
Write equation. 
(2) Place a clean piece of copper into some of the solu- 
tion and let stand for some time, note the effect and explain 
(Reinsch test). 
The antidote is freshly prepared ferric hydroxide and 
water, given ad libitum. 
* This substance and its fumes are very poisonous. 36 
MARSH TEST FOR ARSENIC AND DISTINCTIONS 
BETWEEN ARSENIC AND ANTIMONY 
Hydrogen arsenide. 
Prepare a hydrogen generator consisting of a flask (500 
c.c.), rubber stopper with two holes, a funnel tube and a 
jet tube for burning the gas. Place some pure zinc in the 
flask and add enough distilled water to cover it. Then pour 
in through the funnel tube some pure concentrated sul- 
phuric acid until there is a brisk evolution of gas. Wait 
a few moments to allow the hydrogen to drive all the air out 
(otherwise, when a flame is applied there will be an explo- 
sion), then light the gas. Observe. 
The color of the flame: It should be dark blue or color- 
less, not grayish blue (indicating arsenic). 
Place a piece of cold porcelain in the flame. No dark 
spots should appear on the porcelain. Now add a few 
drops of a solution of arsenious acid and observe change 
in the color of the flame. 
Place the porcelain in the flame, as before. Brownish 
black spots with a metallic luster indicate arsenic. Test the 
solubility of the spots in: (a) chlorine water, should be 
soluble; (Z>) in hydrochloric acid, should be insoluble. 
Hydrogen antimonide. 
Set up a similar apparatus and use a solution of anti- 
mony chloride. 
Observe the color of the flame, which should be grayish. 
The spots on the porcelain should be somewhat sooty in 
appearance, blacker and lusterless. 37 
Test the solubility of the spots in (a) chlorine water, 
should be insoluble; (&) hydrochloric acid, should be soluble. 
Other distinctive tests. 
A solution of arsenious acid or arsenite, made slightly 
acid with hydrochloric acid, treated with hydrogen sul- 
phide, gives a yellow flocculent precipitate of arsenic sesqui- 
sulphide. 
With the same reagent a solution of antimony gives an 
orange flocullent precipitate of antimony sesquisulphi de. 
TESTS FOR ACID GROUPS (ANIONS) 
Tests for hydrochloric, nitric, sulphuric, phosphoric and 
some others have already been given. 
Nitrous Acid or Nitrous Ions. 
Add some dilute acetic acid to the solution and test with 
iodide starch paper; a blue color is formed. 
Sulphurous Acid or Sulphite Ions. 
Add some sulphurous acid solution to a weak solution of 
potassium permanganate. 
What do you observe? 
Explain the action. 
Try the same test, using a dilute solution of fuchsin. 
What do you observe? 
Oxalic Acid or Oxalate Ions. 
Add a mixture of lime water and calcium chloride to the 
solution, a white crystalline precipitate = calcium oxalate. 38 
Insoluble in acetic acid, but soluble in dilute hydrochloric 
acid. 
The precipitate, after ignition, effervesces with dilute 
acids, due to the changing of the oxalate into the carbonate. 
Acetic Acid or Acetate Ions. 
Add some ethyl alcohol to the substance contained in a 
large test tube, then carefully about i c.c. of concentrated 
sulphuric acid, and heat. Observe the odor of ethyl acetate 
(acetic ester). 
Lactic Acid (Uffelman). 
A few c.c. of a i per cent solution of phenol is mixed with 
a few drops of a io per cent solution of ferric chloride. If 
to this purple-colored solution some lactic acid is added, the 
purple will change to a bright yellow. 
Tartaric Acid. 
Add a mixture of lime water and calcium chloride to the 
solution, filter off the white precipitate of calcium tartrate 
(soluble in potassium hydroxide).. Heat it in a porcelain 
dish with concentrated sulphuric acid. It chars with the 
odor of burnt sugar. 
Citric Acid. 
A mixture of lime water and calcium chloride added to 
the solution gives a white precipitate of calcium citrate. 
The precipitate is insoluble in potassium hydroxide (dis- 
tinction from tartrate). 39 
Salicylic Acid. 
Place some of the substance in a test tube with about 
half an inch of methyl alcohol, then add concentrated sul- 
phuric acid and heat carefully. The odor of oil of winter- 
green proves salicylic acid. 
Uric Acid. 
(Murexid test.) Place some uric acid in a porcelain 
dish, add two drops of concentrated nitric acid and evap- 
orate on the water bath to dryness. Cool and add one drop 
of ammonium hydroxide, a rich purple color will appear. 
TESTS FOR BASES 
The tests for potassium, sodium, lithium and ammonium 
have already been given. 
Calcium. 
To a solution containing calcium ions, either neutral, 
alkaline, or slightly acid with acetic acid, add ammonium 
oxalate, a white crystal precipitate = calcium oxalate. 
The precipitate is soluble in dilute hydrochloric acid, 
and nitric acid, but insoluble in acetic acid. 
Magnesium. 
To a solution containing magnesium ions add ammo- 
nium hydroxide, then ammonium chlorid, until clear, and 
finally disodium hydrogen phosphate, a white, crystalline 
precipitate = ammonium magnesium phosphate. The pre- 
cipitate is soluble in dilute acids. 40 
Iron (may be Ferrous or Ferric) 
(a) Ferrous. 
Add to a solution of a ferrous salt potassium ferricyanide, 
a blue precipitate = ferrous iron. 
(Z>) Ferric. 
Add to a solution of a ferric salt ammonium sulpho- 
cyanate, a blood-red color = ferric iron. This test reversed 
can be used to determine the presence of sulphocyanate 
ions, ferric chloride being the reagent (see page 52.) 
Lead. 
Soluble lead salts give: 
(a) With soluble chlorides, a white, heavy precipitate 
of lead chloride soluble in boiling water. 
(&) With soluble chromates, a yellow, heavy precipitate 
of lead chromate insoluble in acetic acid. 
Mercury (may be Mercurous or Mercuric). 
Mercurous: Soluble salts give a white, heavy precipitate 
with soluble chlorids; insoluble in hot water. Changed to 
a black insoluble compound by ammonium hydroxide. Black- 
ened by stannous chloride. 
Mercuric: With a small amount of stannous chloride 
a white, heavy precipitate of mercurous chloride. This 
precipitate, by the further addition of stannous chloride 
is reduced to mercury and becomes black. 
Silver. 
Soluble silver salts with the soluble chlorides give a white 
curdy precipitate, insoluble in boiling water; soluble in 
ammonium hydroxide. 41 
Copper. 
(a) The blue color of copper salt solutions, even when 
very faintly colored are strongly intensified by the addi- 
tion of ammonium hydroxide. 
(Z») Solutions made acid with acetic acid, on the addition 
of potassium ferrocyanide give a red brown precipitate of 
copper ferrocyanide. 
Bismuth. 
Solutions of the nitrate or of the chloride, on the addi- 
tion of water, give a white heavy precipitate of a basic salt, 
insoluble in water, but soluble in dilute hydrochloric or nitric 
acid. 
Tin (may be Stannous or Stannic). 
Stannous salts react with mercuric chloride (see mer- 
cury) to form a heavy white precipitate of mercurous chloride 
or calomel. 
Stannic salts are not affected by mercuric chloride. They 
are changed by boiling with ammonium nitrate or sodium 
sulphate, into meta stannic acid, a heavy white precipitate. 
Gold. 
(a) To a solution of auric chloride add a slight excess 
of ferrous sulphate. Notice change in appearance. Allow 
the solution to stand for several hours. Filter, wash the 
brown precipitate dry, and rub with a knife blade. What 
do you observe? 
(&) Add to a solution of auric chloride heated to a tem- 
perature of about 50° C., a strong solution of oxalic acid. 
Raise temperature slowly to boiling. What do you observe? 42 
When the reaction is over allow to stand. 
(1) Note color of the solution. 
(2) Color of the precipitate. 
Filter off the latter, wash, dry, and burnish. 
Write equations for both reactions. 
Platinum. 
Hydrochlorplatinic acid is precipitated by potassium 
chloride and also ammonium chloride. 
Add a strong solution of ammonium chloride to a solu- 
tion of hydrochlorplatininc acid and an equal volume -of 
95 per cent alcohol. A yellow, crystalline precipitate of 
ammonium platinic chloride will be formed. 
Filter off the precipitate, dry and ignite in a porcelain 
crucible. The residue is spongy platinum. 
(1) Burnish some and notice the metallic luster. 
(2) Warm a portion to remove moisture, cool and allow 
hydrogen gas from the jet of a generator to come in con- 
tact with the spongy platinum. 
Explain the phenomenon. 
All these tests cannot be used in mixtures, but aid in the 
study of the properties of the individual acids and bases. 
EXAMINATION OF PHENOL 
Condition: 
Color: 
Odor: 
Solubility in: 
(а) Water: 
(б) Alcohol: 43 
Test with ferric chloride solution. A deep blue violet 
color is formed which does not fade. 
Compare Phenol with Creosote. 
(1) Condition on cooling. 
(2) Solubility in water. 
(3) Solubility in alcohol. 
(4) Action on albumen solution. 
(5) Action on collodion. 
(6) Action on ferric chloride. 
SPECIAL TESTS 
Fats. 
Acrolein test. 
Fats are esters, that is, compounds containing a hydro- 
carbon radical (propenyl), joined to a fatty acid radical. 
When heated, better with potassium bisulphate, they break 
down and give acrolein or acrylic aldehyde, which has a 
strong pungent characteristic odor. 
Color test. 
The presence of fat, diffused through a solution may be, 
recognized under the microscope by staining the globules 
with Sudan III, which gives them a red color. 
Carbohydrates. 
Molisch test (for all carbohydrates). 
Add a few drops of an alcoholic solution of alpha-naphthol 
to the carbohydrate. Then introduce some concentrated 
sulphuric acid, by means of a pipette, below the mixture. 
Where the two solutions meet, a purple ring will form. 44 
Test for Starch. 
Add some iodine solution to a starch mixture. A deep 
blue color, which disappears on heating, but returns on cool- 
ing, shows starch. 
Fehling's test (for glucose or reducing sugars). 
Mix equal parts of copper sulphate solution, and alkaline 
Rochelle salt solution,* in a large test tube, add an equal 
volume of distilled water and boil. Add a small portion 
of the sugar solution and boil again. A bright red precipi- 
tate of cuprous oxide = reducing sugar. 
Bismuth Reduction Test. 
Heat some Nylander's solution f with the reducing sugar, a 
black or brown black precipitate of bismuth oxide = reducing 
sugar. 
Phenyl Hydrazine Test. 
Add to a glucose solution some sodium acetate, and a 
small quantity of phenyl hydrazine hydrochloride. Heat 
to boiling and allow to stand until the next period. A beau- 
tiful yellow crystalline precipitate of phenyl glucosazone will 
be observed. 
The precipitate will have a definite crystalline form 
and a definite melting point for a given sugar, and may there- 
for be used as a means of identification. 
Examination of cane sugar and comparison with dextrose. 
(i) Examine some crystals under the microscope, note 
form of crystals and draw some. 
Make a 5 per cent solution and try: 
(1) Molisch test. 
(2) Fehling's test. 
* Fehling's mixtuie. 
f Nylander's solution is composed of bismuth subnitrate, Rochelle salt, 
and made alkaline with sodium hydroxide. 45 
Invert some sugar by heating a solution with 2 or 3 drops 
of hydrochloric acid cone, for about fifteen minutes, neu- 
tralized acid and test. 
(1) Molich test. 
(2) Fehling's test. Note changes and explain. 
Proteins. 
Biuret Test. 
Heat the protein with sodium hydroxid solution, and after 
cooling, add slowly a dilute solution of copper sulphate, a 
pink or violet color = protein. 
Millon's Test. 
Add some Millon's reagent * to the protein and on boiling 
a red precipitate or color is formed. 
Lieberman's Test. 
Add a few c.c. of hydrochloric acid cone, to a protein, 
and warm. A deep purple or violet color will be formed, 
which disappears after a time. 
Xanthoproteic Test. 
Heat the protein with concentrated nitric acid, and 
after cooling, add ammonium hydroxide carefully; a deep 
orange color will be formed. 
No single test is sufficient to prove protein, several or 
all of the above should be used. 
EXAMINATION OF BONE TISSUE 
Bone is composed of earthy and animal (cellular) matter 
in the proportion 67 per cent of the former, bone earth, 
and 33 per cent of the latter, organic. The animal matter 
* It consists of an aqueous solution of mercuric nitrate with some nitrous 
acid. 46 
is chiefly collagen, which is converted into gelatine by boil- 
ing in water. The earthy matters are given in the table 
below. The animal and earthy consitutents are so inti- 
mately blended that it is very difficult to separate them. 
A strong red heat is necessary to remove the organic 
matter. Dilute acids will remove the earthy matters, leaving 
a cartilaginous-like mass in the original form, which is very 
flexible. 
COMPOSITION OF GREEN BONE 
Water 51.00 
Fat 15.50 
Ossein 11.50 
Bone earth 22.00 
COMPOSITION OF BONE EARTH 
Tricalcium orthophosphate 85.00 
Calcium carbonate 9.00 
Calcium fluorid 2.40 
Trimagnesium orthophosphate.. 1.60 
Sodium chlorid 1.00 
Sodium carbonate 1.00 
Tests for: 
Water.-Heat some bone in a dry test tube held at an 
angle of 30° and notice that water collects on the side of the 
tube. What elements are present? 47 
Gases. 
Carbon dioxide.-Pass gases through lime water. 
Ammonia.-Wet red litmus paper. 
Hydrogen sulphide.--With wet lead paper. 
Oils and tars.-Notice appearance, odor, reaction, etc. 
Residue from distillation-Bone black.-Burn off carbon 
and examine the ash. 
TESTS FOR MINERAL PART OR BONE ASH 
Dissolve some bone ash in dilute nitric acid. Notice 
effervescence. Then test for sodium as usual. 
Calcium, Magnesium, Chlorine, Phosphorus. 
Divide the above solution into three parts. 
Make one part alkaline with ammonium hydroxide, 
and then acid with acetic acid; now add ammonium oxalate 
in excess, heat the solution and filter; a white crystalline pre- 
cipitate = calcium oxalate. Make flame test for calcium. 
To the filtrate add a few drops of ammonium oxalate, 
to be sure that all the calcium has been precipitated. Then 
cool, add disodium phosphate and make alkaline with am- 
monium hydroxide; a white crystalline precipitate=ammo- 
nium magnesium phosphate. 
With another portion test for chlorine ions. 
With the third portion, test for phosphoric ions. 
Sulphur. 
Fuse several small pieces of bone with sodium carbonate 
and some potassium nitrate in a test tube. Cool, add dis- 
tilled water to the mass, warm and filter if necessary. Add 48 
hydrochloric acid dilute and barium chloride, a white crys- 
talline precipitate indicates barium sulphate. 
Fat (a mixture of Stearin, Palmitin and Oelin), 
Shake a piece of dry green bone with some ether in a 
test tube; pour off the ether and evaporate the solution 
in a porcelain dish. Heat the residue; a strong pungent 
odor indicates acrolein or fat. 
To separate ossein from bone earth, place a piece of 
bone in dilute hydrochloric acid (20 parts of water to one 
of acid), and allow to stand for forty-eight hours, then 
examine. 
TESTS ON TEETH 
Break a tooth into two or three pieces and heat strongly 
in a small test tube. 
Does it act like bone? 
Place a tooth in dilute hydrochloric acid (see Bone Test) 
and let stand until next time, then examine and compare 
with bone. 
A qualitative analysis of teeth can be made in the same 
way as for bone, but is much more difficult as some of the 
constituents are in very small quantities. 
Test a tooth for calcium, phosphoric and carbonic ions 
in the same manner as for bone. 
EXAMINATION OF MILK 
Milk is the first food taken by the newly born and con- 
tains all the necessary constituents for growth. It is secreted 
by the mammary glands, and, though varying with different 49 
species, has very much the same composition in all. It 
also varies in the same animal with environment, nervous 
conditions, use of drugs, etc. 
The following tables give a fair average analysis of 
human and cow's milk: 
Composition. 
Human 
Cow's 
Water 
88.00 
87.50 
Fat 
3-5o 
3-5° 
Proteins 
i-75 
4.00 
Sugar 
6.50 
4-25 
Salts 
25 
•75 
Examination and Tests. 
Color: 
Odor: 
Taste: 
Specific gravity (use lactometer): 
Action on litmus: Also on lacmoid for free acid. 
Examine some under the microscope for fat, colostrum, 
etc. 
Precipitate caseinogen, as casein, by adding slowly i 
per cent acetic acid to 20 c.c. of milk, until distinctly acid; 
stir well, filter. Precipitate (casein), test with Millon's 
reagent for protein. 
Heat the filtrate to boiling, allow to stand, then filter 
until clear. The precipitate consists of lact-albumin and 
lact-globulin and may be tested for protein, but usually 
the protein is too small in amount. 
Test the filtrate for potassium and sodium (flame tests), 
then make slightly alkaline with potassium hydroxid, heat 
and filter off the phosphates of calcium and magnesium. 50 
Precipitate. Dissolve in acetic acid, and add ammonium 
oxalate precipitate = calcium oxalate. Filter off the calcium 
oxalate and precipitate the magnesium as usual. 
Filtrate. 
Test a portion for reducing sugar (lactose) with Fehling's 
mixture. 
Also test a portion for chlorids and phosphates as usual. 
Milk also contains other elements which cannot be tested 
for by simple methods (see Hammarsten's Physiological 
Chemistry). 
In order to test for fat, take some of the casein precipi- 
tate which carries down the fat with it, dry and extract 
with ethyl ether. Evaporate the ether solution in a porce- 
lain dish on the water bath, and make the acrolein test on 
the residual fat. 
EXAMINATION OF SALIVA 
Saliva is the first digestive juice to come in contact with 
and to act upon the food. 
It is a mixture of secretions from the parotid, submax- 
illary and sublingual glands. There is also some mucus 
mixed with it. Amount secreted about 1,200 grams a day. 
Composition. 
Water 994.00 
Solids 6.00 
Specific gravity varies from 1.002 to 1.009. 
It is often slightly alkaline, but may be neutral or even 
acid. 51 
When saliva is allowed to stand, sediment collects in the 
bottom of the glass. This consists of epithelieal cells, corpus- 
cles (like blood), calcium carbonate, phosphates, etc. 
Make a microscopic examination of the sediment. 
Analysis of mixed saliva:- 
Water 992.50 
Solids 7.50 
Epithelial cells 1.10 
Fat 0.06 
Mucin 1.50 
KS'CN, not always present... 0.04 
Ptyalin and maltase 2.70 
Na, K, Ca, Mg salts 2.10 
TO COLLECT SALIVA 
First, wash out the mouth with water, to remove foreign 
substances, then collect saliva, and to increase the flow, a 
piece of clean rubber, chewing gum freed from sugar, or 
paraffin, may be used. The last is best. 
TESTS 
Color: 
Odor: 
Appearance: 
Sediment: 
Use microscope. 
Reaction: 
Specific gravity, (use hydrometer.) 52 
Albumen. 
Heat clear saliva (filter to clear if necessary), turbidity 
or cloudiness at the upper part of the test tube shows albumen. 
Filter and test precipitate with Millon's reagent. 
Sulphocyanate. 
Put some saliva into a test tube, add two drops of hydro- 
chloric acid, dilute, shake, and add a drop or two of ferric 
chloride, blood red color = ferric sulphocyanate. 
Ptyalin. 
(Starch enzyme.) Ptyalin may be precipitated from 
saliva by alcohol, but it takes time and is not necessary for 
the test. Add some starch paste to saliva, heat on water 
bath (temperature, about 40° C.), for several minutes. 
(Saliva may be slightly alkaline.) Test a few drops from 
time to time with iodine solution until blue color disappears, 
and then note red color, and continue until it disappears. 
Then test for glucose. 
Mucin. 
Put some dilute acetic acid (about 2 per cent) in a test 
tube, and add a few c.c. of saliva. Shake and examine. 
Thick, stringy masses = mucin. 
Filter off the mucin, wash with water, place in a tube 
and test with Millon's reagent for protein. 
Mucin is a glyco-protein and on cleavage yields a simpler 
protein and a reducing carbohydrate. Heat some mucin with 
water and a few drops of hydrochloric acid for several min- 
utes. Filter and test the filtrate with Fehling's mixture. 53 
Carbonates. 
Shake some saliva in a test tube with lime water, and 
filter; to precipitate, add some dilute hydrochloric acid, 
an effervescence = carbon dioxid = carbonates. 
Ammonia. 
Place about io c.c. of saliva in a large test tube with 
cork and long bent tube. Make the saliva alkaline with 
pure caustic potash. Distil off 5 c.c. of the liquid and test 
the distillate with Nessler's reagent. 
INORGANIC SALTS 
ACIDS AND BASES 
Make some saliva alkaline with ammonium hydroxide, 
warm, filter, dissolve precipitate in nitric acid dilute and 
divide into two parts, one-third and two-thirds. 
Use one-third for tests for potassium, sodium, sulphuric 
chlorine, phosphoric ions. 
Use two-thirds for tests for calcium and magnesium as 
in bone. 
Sometimes it is well to test for uric acid or urates; use 
muroxide test. Sometimes tests are made for metals, as 
mercury, copper, etc. 
Mercury. 
The mercury may be a soluble salt, metallic mercury 
or some insoluble compound. 
Collect an abundant supply of saliva, place it in a por- 
celain dish, add dilute hydrochloric acid, heat on water bath 
for some time, and filter. 54 
(a) Residue 
Place in a beaker, add hy- 
drochloric dilute, and heat to 
boiling, add some crystals of 
potassium chlorate and heat 
again. Boil until odor of 
chlorine has disappeared, and 
test a portion for mercury as 
in (&). Add stannous chloride 
to another portion, a white 
precipitate (mercurous chlo- 
ride) becoming black on fur- 
ther addition of stannous 
chloride = mercury. 
(b) Filtrate 
Place a piece of clean 
copper in the solution and 
allow to stand; if a gray de- 
posit forms on the copper, 
take out the copper, dry 
and heat in a tube; metallic 
globules on the tube, like sil- 
ver = mercury. 
EXAMINATION OF URINE 
The following scheme is mostly for clinical purposes: 
In selecting a specimen of urine for examination, it should 
be a part of the whole twenty-four hours urine, otherwise 
the specific gravity, reaction and other properties will be 
incorrect. (A part of that passed before breakfast may be 
used.) Normal urine is a transparent, aqueous liquid of 
pale yellow or amber color, usually acid in reaction, with 
a characteristic odor (urinous or aromatic), specific gravity, 
1.020 average; quantity 1,500 c.c. (50 oz.), in twenty-four 
hours. The quantity varies with season, amount of liquid 
taken into body, disease, etc. It is increased in cold weather, 
diabetes, chronic interstitial nephritis, by certain drugs, 
etc.; decreased in acute nephritis, fevers, hot weather, by cer- 
tain other drugs, etc. 55 
Average Analysis: 
Water 950.00 
Urea 28.00 
Uric acid 0.60 
Hippuric acid 0.35 
Creatinine 0.65 
Extractives 8.40 
Sodium chloride 7.50 
Phosphoric acid 2.20 
Sulphuric acid 1.25 
Calcium oxide 0.25 
Magnesium oxide 0.30 
Potash and soda 0.50 
Examination.-Color, odor, general appearance, whether 
clear, smoky, cloudy, turbid, etc. Acid, alkaline, neutral or 
amphoteric. The quantity in twenty-four hours. Specific 
gravity (1.020 normal), may vary somewhat in health. 
Low specific gravity, 1.010 or under, indicates albumen. 
High specific gravity, 1.0030 or over, indicates glucose. 
Some of the urine should be centrifuged and the sedi- 
ment examined for cells, crystals, bacteria, casts, etc. 
Inorganic. 
Add a few drops of nitric acid, boil, filter, and test filtrate 
for bases and acids, as in saliva. 
Ammonium. 
Use lime water instead of potassium hydroxide, as the 
latter converts urea into ammonia, and test as usual. 56 
DETERMINATION OF UREA (Doremus) 
Fill the ureometer with the alkaline hypobromite solu- 
tion and introduce, with the special pipette, i c.c. of urine 
very slowly. The gases formed are carbon dioxide and ni- 
trogen, the former is absorbed by the alkali, while the latter 
collects in the upper part of the tube. Then read off the 
number of divisions on the tube of the ureometer. Each 
division = mg. of urea for i c.c. of urine. Knowing the 
volume of urine for twenty-four hours, and its specific gravity, 
the total urea or nitrogen output may be easily found by 
calculation. 
ALBUMEN 
Boiling Test. 
Fill a test tube half full of clear urine (filtering, if neces- 
sary), and heat to boiling. If it remains clear, albumen is 
absent. If it becomes cloudy, add a few drops of acetic 
acid and heat; it if still remains cloudy, it shows the pres- 
ence of albumen.* 
Nitric Acid Test (Heller). 
Warm some nitric acid concentrated in a test tube and 
allow some urine to flow down the side of the tube so as to 
float on top. A white ring or cloud is formed where the two 
liquids meet if albumen is present. 
* Urine on standing often becomes cloudy from the precipitation of 
phosphates. 57 
GLUCOSE 
Before testing for glucose, albumen, if present, should 
be removed by adding two or three drops of acetic acid, 
boiling, and filtering. 
Boil some Fehling's mixture (equal parts of each solution) 
and an equal volume of water in a test tube, then add a 
little of the urine and boil again. Allow to stand and see if 
there is any red or yellow precipitate of cuprous oxid. It 
may be necessary to add urine several times and boil before 
any precipitate appears, especially if the amount of glucose 
is small. Fehling's solution may be precipitated by glu- 
curonic acid and some other substances. The best method 
of proving the presence of glucose is the fermentation test. 
Good results may be obtained by the use of Eichorn saccha- 
rimeter. 
Uric Acid. 
Make some urine acid with hydrochloric acid dilute and 
allow it to stand for some time. The uric acid will be set 
free, crystallize out and collect at the bottom of the vessel, 
as hard, dark, colored grains, like sand. Use microscope. 
Take some of the crystals, put them into a porcelain dish, 
add one or two drops of concentrated nitric acid, and evap- 
orate on the water bath to dryness. Cool and add one drop 
of ammonium hydroxide, a rich purple color shows uric acid. 
Acetone Test (Legal). 
To the urine add a few drops of sodium nitroprusside 
solution and make alkaline with potassium hydroxide; a 58 
red color forms, which, on the addition of acetic acid, darkens 
or becomes the color of port wine, if acetone is present. 
If the red color first formed, if bleached by acetic acid, 
is due to creatinine. 
Bile Pigment. 
Pour about an inch of yellow concentrated nitric acid 
into a test tube. Then, holding the tube somewhat inclined, 
allow some urine to flow down and rest on the acid, where 
the two liquids come together, a green ring = bile pigment. 
Other colors may be produced, but the green is most im- 
portant. 
Indican Test. 
Add an equal volume of concentrated hydrochloric acid 
to some urine in a large test tube, and about i c.c. of carbon 
tetrachloride, which will sink to the bottom. Then add 
ferric chloride, drop by drop, shaking after each addition. 
The carbon tetrachloride globule will be colored blue if indican 
is present. 
Diazo reaction (Ehrlich). 
This test requires two solutions. 
(а) Make a o.i per cent solution of sulphanilic acid in 
20 per cent hydrochloric acid. 
(б) A 0.5 per cent solution of sodium nitrite in water. 
Mix about 10 c.c. of each solution and make strongly 
alkaline with ammonium hydroxide. 
Add this mixture to an equal volume of urine and shake. 
A bright red color will appear if the reaction is positive. 
(See Hammarsten.) 
FINIS