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THE GIFT OF
GINN AND COMPANY

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3 2044 097 019 657

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LABORATORY EXERCISES

TO ACCOMPANY

FIRST PRINCIPLES OF CHEMISTRY

BY
RAYMOND B. BROWNLEE ROBERT W. FULLER

STUYVESANT HIGH SCHOOL STUYVESANT HIGH SCHOOL

WILLIAM J. HANCOCK MICHAEL D. SOHON

ERASMUS HALL HIGH SCHOOL MORRIS HIGH SCHOOL

JESSE E. WHITSIT

DE WITT CLINTON HIGH SCHOOL
ALL OF NEW YORK CITY

ALLYN AND BACON
Bogton anti Cijicago

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toti^^"rii.^.or:L36

NARVAKD COltEGg UUWM

GIFT OP
QlNiM & COMPANY '

MARCH 17, itsy: I

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PREFACE.

This Laboratory Manual is designed to accompany the
authors' " First Principles of Chemistry." It is, in some meas-
ure, founded on Handbook 21 of the State Department of
Education of New York, which was prepared by the authors
in the spring of 1905, and which met with such success as to
lead to the writing of the " First Principles of Chemistry."

Such of the experiments from the Handbook as appear in
the present Manual have been carefully revised and improved
where experience has shown this to be desirable. A number
of other experiments have been added in order to give greater
freedom of selection, and to provide fully for such schools as
are favored with ample time for laboratory work. The authors
believe that these exercises will be found to furnish a typical
rafnge of experiments suitable for an elementary course.
Though practical and industrial applications receive consid-
erable attention, yet a sound knowledge of the fundamental
facts and principles of the science is considered of most im-
portance to the beginner, since it is only through painstaking
labor along theoretical lines that the achievements of indus-
trial chemistry have been obtained.

It is hoped that the Manual will prove an attractive intro-
duction to the experimental determination of chemical facts,
and will lead the pupil to an interest in chemical theory for
its own real and permanent value.

The authors gratefully acknowledge indebtedness to that
large body of chemistry teachers whose kind reception of
the " First Principles of Chemistry " has encouraged them to
publish the present laboratory course.

New York, September, 1908.

iii

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GENERAL SUGGESTIONS TO TEACHERS.

Selection of Experiments. — The time usually allotted to
laboratory work in a first course in Chemistry is not sufficient
for performing all the experiments given in this manual.
As an aid in the selection of a well-balanced course, the
experiments are divided into the following groups :

Group A. Nos. 1, 2, 3, 4, 6, 6, 7, 8, 9, 10, 14 A or 14 B, 15,
16, 17, 19, 21, 25y 26, 27, 28, 29, 31, 32, 33, 34, 35, 38, 39,
40, 43, 44, 47, 48, 49, 50, 51, 52, 54, 58, 59, 60, 66, 67, 68.

Group B. Nos. 11, 12, 13, 18, 20, 24, 41, 42, 53, 57, 64.

Group C. Nos. 22, 23, 30, 36, 37, 45, 46, 55, 56, 61, 62, 63,
65, 69, 70, 71.

It is recommended that all students be required to perform
the experiments of Group A. These experiments are funda-
mental in nature, and very valuable as a means of laboratory
instruction. This list, together with a certain number -of
experiments from Group B, will satisfy the usual college
entrance requirement in Chemistry.

Most instructors will doubtless assign to their classes a good
portion of the exercises in Group B. The several quantitative
experiments in this subdivision are valuable for their training
in manipulation, for the theory they illustrate, and for the
interest they arouse.

It is hoped that every laboratory section will find time for
some of the experiments in Group C, particularly those dealing
with the practical applications of Chemistry.

The Birections for the Experiments. — At first the directions
for the laboratory operations are somewhat detailed, that the

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VI GENERAL SUGGESTIONS TO TEACHERS.

beginner may have the help needed to perform the experiment
readily and intelligently. As the student gains in experience
and self-reliance, the directions become less full.

The questions in ordinary type generally call for statements
of fact. The answers to them should be woven into the written
description of the laboratory operations and their results.

The questions in italic require reasoning from the observed
experimental data. It is often advisable for the student to
postpone the recording of answers to these italicized questions
until the operations of the experiment have been completed.
Many instructors prefer to have the answers to such questions
form a separate part of the note-book record under some such
heading as Discussion, The authors have taken great care
to avoid questions which the student cannot fairly or legiti-
mately answer from the experimental data. In some cases
Cla^ss Discussion appears in parentheses after certain ques-
tions. This means that the student requires further informa-
tion in order to give a complete answer. Such information is
often best furnished in a class discussion.

The tabular forms for numerical data should be written in
the laboratory note-book at the beginning of the experiment, so
that the measurements may be recorded as soon as they are made.

Apparatus and Material. — It has been the aim of the authors
to use such simple forms of apparatus as are commonly found in
the ordinary laboratory equipment. For their general availa-
bility, attention is called to the agate pans and the Syracuse
form of watch glasses. This watch glass is superior to glass
plates for covering and handling bottles of gas. Although
the brass capsule, ramrod, and holder used in Experiments 8
and 14 B can be purchased, many instructors will prefer to
have them made in the laboratory shop. Accordingly, direc-
tions for making them are inserted here.

The sodium capsule is made either (a) by cutting ^" brass
tubing (^" wall) into pieces about an inch long, and soldering
a brass disk ^" thick into one end ; or (b) by drilling -j^" brass

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GENERAL SUGGESTIONS TO TEACHERS. vii

rod with a \'' or -^^ drill. The latter can be readily done by
mounting the rod in a draw-in chuck in a lathe, first drilling
and then cutting off.

The handle consists of a piece of No. 14 copper or brass wire.
A few turns are wrapped tightly around the capsule, and about
8" of the wire project at right angles to the capsule. The outer
end of the wire should either be bent into a flat loop or be
forced into a short piece of dowel rod.

A ramrod of iron or brass, about 5" long, sliding easily in
the capsule, should be provided.

In the lists of material, concentrated acid means acids of the
indicated specific gravity: hydrochloric acid, 1.19, sulphuric
acid, 1.84, and nitric acid, 1.42. The concentrated ammonia
water should have a specific gravity of 0.90.

For dilute acids and ammonium hydroxide the authors com-
monly employ* the following concentrations : —

Ammonium hydroxide (1 : 4), that is, one part by volume of
concentrated ammonia water to four volumes of water.

Hydrochloric acid (1 : 4)

Nitric acid (1 : 4)

Sulphuric acid (1 : 6)

All students shovtd he given, early in their course, definite
directions for the safe mixing of concentrated sulphuric add with
water. The required amount of water should he measured out.
Then small portions of the concentrated acid should he poured
slowly into the water, and the mixture should he ajgitated after
each addition.

In many cases special concentrations for acids and other
solutions are given at the head of the experiment. When no
concentration is expressed, one to ten is understood, that is,
one part by weight of the chemical to ten parts by weight of
water. (A cubic centimeter of water at ordinary temperature
is considered to weigh one gram.) In the majority of cases,
however, one to twenty solutions will be found to work quite
as well as the one to ten, with a consequent saving of reagents.

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viii GENERAL SUGGESTIONS TO TEACHERS.

It will be found convenient to have ready for the students
when they come into the laboratory the solutions listed in the
Material for the various experiments.

Several of the experiments require solid chemicals in small
amounts. In such cases, the authors have often found it
advisable to distribute the chemicals on labeled slips of
paper (about 5 X 10 cm.), arranged in places easily accessible
to the students.

In taking specified quantities of solutions, students may
need graduates in some cases ; but more frequently the neces-
sary quantity may be measured as a fraction of a test-tubeful.
The ordinary test-tube (6 X f ") contains 30 c.c.

In cases when only one or two cubic centimeters of a
solution are to be taken, the solutions can be drawn from bu-
rettes, which should be labeled and accessible.

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CONTENTS.

Care and use of apparatus
Drawings . ...

BXPBRIMBNT

1. Heating metals in air . . .

2. Weiglit change on lieatlng a metal .

3. Decomposition of a compound formed by heating a

metal in air ....

4. Percentage of oxygen in air . .

5. Preparation of oxygen

6. Formation of oxides

7. Electrolysis of water

8. Decomposition of water by sodium . .

9. Preparation of hydrogen .

10. Properties of hydrogen

11. Distillation of water .

12. Saturated solutions ....

13. Water of crystallization .
14 a. Equivalent of magnesium
14^. Equivalent of sodium

15. Preparation and properties of chlorine

1 6. Preparation and properties of hydrochloric acid

17. Test for a chloride

1
4

8
9
11
13
14
16
17
16
19
21
22
24
26
26
30
32

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CONTENTS

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PAOB

18.

Weight of a liter of oxygen ....

. 34

19.

Bases

. 36

20.

Titration

21.

Flame tests

22.

Acid and normal salts

23.

Solvay process for sodium bicarbonate

24.

Water of crystallization in barium chloride (quantita-

tive)

25.

Forms of sulphur . . . . .

26.

Preparation of metallic sulphides

27.

Preparation and properties of hydrogen sulphide .

28.

Preparation of sulphur dioxide ....

29.

Properties of sulphur dioxide . . .

. 51 '

30.

Preparation and properties of nitrogen

. 53

31.

Preparation of ammonia

32.

Properties of ammonia

33.

Preparation and properties of nitric acid

34.

Preparation of nitric oxide . .

35.

Properties of nitric oxide

36.

Preparation and properties of nitrous oxide

37.

Preparation of potassium nitrate ...

38.

Preparation and properties of bromine

39.

Preparation and properties of iodine . . . .

40.

Halogen acids

41.

Carbon by destructive distillation . . , ,

42.

Properties of carbon

43.

Preparation and properties of carbon dioxide

44.

Hard waters

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CONTENTS

water puri-

BXPBRIMBMT

45. Carbon monoxide ....

46. Borax and boric acid

47. Double decomposition by precipitation

48. Four ways of preparing a salt .

49. Cobalt nitrate tests ....

50. Borax bead tests ....

51. Identification of simple salts

52. Action of metals on salt solutions

53. Equivalent of silver ....

54. Aluminum hydroxide (use in dyeing and in

fication)

55. Dyeing — direct dyes

56. Dyeing — basic dyes . . .

57. Preparation of double salts

58. Tests for iron salts ....

59. Reduction of ferric to ferrous chloride

60. Oxidation of ferrous to ferric chloride
Silver salts in photography
Cyanotype or blue-print process
Chromium compounds

64. Qualitative separation of lead, mercury, and silver

65. Baking powders ....

66. Fermentation

67. Preparation of an ethereal salt .

68. Soap-making

69. Tests for nutrients ....

70. Analysis of milk

71. Analysis of flour . . • .

61,
62.
63.

PAOB

76
78
79
81

82
83
84
85
86

100

101

102

105

107

109

112

114

115

117

119

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Xll CONTENTS

Appendix p^ob

Atomic Weights of the Important Elements . .121

Table of Solubilities 122

General Rules for Solubility 123

Volatility of Compounds . . . . . .123

The Metric System 124

Pressure of Water Vapor 126

List of Supplies 127

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LABORATORY EXERCISES IN
CHEMISTRY.

CARE AND USE OF APPARATUS.

The accompanying picture (Fig. 1) gives the student
the names of pieces of apparatus with which he is not
familiar. These articles should be kept in a clean and
orderly condition ; good results cannot otherwise be
secured.

Fig. 1.. Laboratory apparatus In common use.

a, test-tube rack; b, Bunsen burner; c, morter and pestle; </, watch glass (Syracuse);
e, thistle-tube ; /, flask ; g, crucible ; h, reagent bottles ; /, evaporating dish ; Ar, fun-
nel ; A beakers.

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2 LABORATORY EXERCISES.

The Burner. — The Bunsen burner should burn with a
clear, blue flame. The ordinary gas flame deposits soot
on objects which it touches. The character of the flame
is regulated by adjusting the quantity of air that enters
the holes at the base of the burner. The flame sometimes
" strikes back, " that is, begins to burn at the base where
the ^ir enters. This usually means that too much air is
entering the tube. Turn off the gas, adjust the movable
ring, and relight the burner.

Heating Glassware. — Vessels made of thin glass, such as
test-tubes, beakers, and flasks, can be heated with safety ;
test-tubes may be put directly in the flame ; beakers and
flasks should be protected by wire gauze or asbestos mat.
Never attempt to heat articles made of thick glass, such as
bottles and battery jars, because the poor conductivity of
glass causes unequal expansion and breakage.

Heating Porcelain. — Evaporating dishes and crucibles
can be heated to very high temperatures. Crucibles are
put directly in the flame, but in this case the heat should
be applied slowly at first.

Setting up Apparatus. — (a) Have everything firmly
arranged and securely placed.

(J) Place the weight of the object directly over the
base of the ring-stand.

((?) Have the rod of the ring-stand away from you,
not toward you.

(d) In using a clamp, do not put great pressure on
thin apparatus.

(e) See that rubber stoppers fit securely, but use care
in pressing them into the necks of thin glass articles.

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CAItE AND USE OF APPARATUS. 8

(/) The lower end of a thistle-tube should dip undei:
the surface of the liquid in the bottle or flask.

(^) The bends in glass tubes should be rounding, not
angular. The latter are likely to break and the flow of a
gas in them is partly obstructed.

(h) Pay a good deal of attention to the " looks " of
your apparatus. Have vertical lines vertical ; horizontal
lines horizontal.

(i) Keep pieces of clean muslin in your locker. . The
directions frequently call for dry tubes and bottles.

To cut Glass Tubing. — Using a triangular file, make a
sharp scratch at the desired point in the tube. Holding
it as shown in diagram (Fig. 2), with the ends of the
thumb nails opposite the scratch, bend the two ends
toward you, at the same
time pulling away from the
point of intersection with
both hands. The result
should be an even cut at
right angles to the tube.

<<Fire-polisliing." — Do not leave cutting edges on the
ends of glass tubes. Hold such ends in the flame of a
burner until the glass just begins to soften.

Bending Tubes. — Use an ordinary fish-tail illuminating
gas burner, or a " wing-burner " which can be put on the
top of a Bunsen burner to make it give a broad, flat
flame. Hold the tube lengthwiBe in such a flame so that
about two inches of it will get the full heat of the burner.
Constantly rotate the tube in order that it may be heated
evenly, but do not bend it, or allow it to bend, while it is

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4 LABORATORY EXERCISES.

in the flame. When the heated portion has become
rather soft, remove it from the flaws and bend it to the de-
sired angle. While bending the tube, " sight " along it
so that you can be sure that the bend will be " flat," that
is, lie entirely in one plane. A good bend should be
rounding, not angular. It is for this reason that it is
necessary to use a broad, flat flame.

DRAWINGS.

The purpose of drawings in the laboratory note book is
not to represent a picture of the apparatus, but to show
that the pupil understands its arrangement and operation.
For this reason, and also for the sake of simplicity, make see-
tionaly not perspective drawings. To illustrate this, a test-
tube and a bottle are shown drawn in both ways (Fig. 3).

a b c

Fi^. 3.

It will be readily seen that in each case the sectional is
the simpler of the two drawings.

In making a sectional drawing, imagine a vertical plane
passing through the middle of your apparatus; then
imagine your paper to be in the position of this plane.

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DBA WING 8. 6

Trace lines where the paper would touch the intersected
apparatus. The accompanying diagram (Fig. 4) is a
sectional drawing of the apparatus used in the prepara-
tion of hydrogen.

Notice carefully the following points:

(a) The bottom of the pan, in which the gas-
collecting bottle stands, is represented by a horizontal
straight line; in a perspec-
tive drawing this would
be a curved line. The bot-
toms of bottles, flasks, etc.,
are always represented by
straight lines.

(J) The rubber stopper
is indicated by cross hatch- Ml
ing (parallel oblique lines).

((?) Water or other liquid ^* '

is represented by horizontal irregular straight lines.

(d) A line is not drawn for the top edge of the thistle-
tube, since this would not show in the imaginary section.
A like thing is true for all open bottles and flasks.

The pupil should aim for skill in making these sectional
drawings rapidly without the use of a ruler.

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6 LABOBATORT EXEBCI8E8.

EXPERIMENT 1.
Heating of Metals in Air.

Apparatus. Bunsen burner, forceps, ring-stand with one
ring, pipe-stem triangle, lid of porcelain crucible, iron wire
15 cm. long.

Material. Copper strips (5 cm. x 1 cm. x 0.5 mm.) or #24
copper wire, 6 cm. magnesium ribbon, granulated tin, sand-
paper.

(a) Scour a piece of copper with sandpaper. Examine
the bright copper, noting its color, luster, and flexibility.
Take hold of one end of the copper with forceps, and hold
the other end in the outer flame of the burner, until it is
red hot. Remove the strip from the flame and watch it
while cooling. Bend the strip. Compare the properties of
the surface material with those observed in the original
copper.

(J) Examine a piece of magnesium ribbon, noting its
color, luster, and flexibility. Using forceps, take hold of
one end of the magnesium. Place the free end of the
ribbon in the flame. Result ? Compare the product with
the magnesium.

({?) Place the lid of a porcelain crucible on a pipe-stem
triangle, supported on a ring-stand. On the crucible lid
put a few pieces of granulated tin, and heat gently at first,
keeping the flame in motion and well below the crucible
lid. When the tin melts, stand the burner beneath the
crucible lid and stir the tin constantly with an iron wire.
Compare the product with the original tin.

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WEIGHT CHANGE ON HEATING A METAL. 7

EXPERIMBNT 2.

Weight Change on Heating a MetaL

Hack student should perform but one experiment^ a, J, or e.

Apparatus, (a) Porcelain crucible, horn pan balance, shot ot
sand, pipe-stem triangle, ring-stand, Bunsen burner, iron wire.
(b) and (c), same as for (a) . except the iron wire.

Material, (a) Granulated tin. (b) copper gauze, or copper
wire, #30, (c) magnesium powder.

(a) Counterpoise a porcelain crucible, c6ntaining about
two grams of granulated tin. Remove the crucible, leav-
ing the counterpoise on the balance.

Place the crucible on a pipe-stem triangle. Heat gently
at first, keeping the flame in motion and well below the
crucible. Gradually increase the heat, and allow the cru-
cible to remain so that it is just above the tip of the
inner cone of the flame for twenty minutes. Stir the tin
frequently with an iron wire.

Remove the burner and allow the crucible to cool on the
triangle.

Place the crucible on the balance. Has there been
a loss or a gain in weight? What explanation can he
made of the change in weight? (Consider the proba-
bility of the air having something to do with the
change.)

(5) Counterpoise a porcelain crucible, containing about
2 grams of fine-meshed copper gauze, or fine copper wire
rolled into a loose ball.

Place the crucible on a pipe-stem triangle. Heat gently
at first, keeping the fiame in motion and well below the
cmoihle. Gradually increase the heat and then allow the

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LABOBATOBT JEXERCISE8.

crucible to remain so that it is just above the tip of the
inner cone of the flame for thirty minutes.

Remove the burner, put the cover on the crucible, and
allow it to cool on the triangle.

Place the crucible without its cover on the balance.
Has there been a loss or gain in weight ? What explanation
can be made of the change in weight f (Consider the proba-
bility of the air having something to do with the change.)

(<?) Using the same method as in (J), heat 0.6 gram of
magnesium powder in a covered crucible. During the
heating, the cover should be tilted from time to time to
admit air.

EXPERIMBNT 3.

Decomposition of a Compound formed by heating a Metal in Air.

Apparatus. Ring-stand and clamp, hard glass test-tube, rub-
ber stopper, delivery tube, dish of water, test-tube, splinter.
Material. Red powder.

(a) Put about 2 grams of the red powder in a hard glass
test-tube fitted with a stopper carrying a delivery tube.

Place the end of the
delivery tube under the
mouth of a test-tube
filled with water and in-
verted in a dish of water.

(J) Do n/)t allow the hard
glass test-tube to cool while
the mouth of the delivery
tube is wider water. Why?

Heat gradually the

Fig. 5.

hard glass tube. What is the cause of the bubbling when
the tube is first warmed? As soon as one half the water

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DETERMINATION OF PEBCENTAGE OF OXYGEN. 9

in the inverted tube is displaced, remove the test-tube,
invert, and put into it a glowing splinter. Result ?

(<?) Collect a second test-tube of gas and test as before.
What is the difference between the behavior of the glowing
splinter in the two test-tubes ? What was the gas in the
first test'tvie f The gas in the second test-tube was oxygen.

(d) Take a splinter and rub the substance which has
collected on the cooler portion of the hard glass tube.
What is the substance?

Of what is the red powder composed? Suggest a method
and the conditions necessary for making the red powder.

EXPERIMENT 4.
Determination of the Percentage of Oxygen in Air (Volumetric).

Apparatus. Glass cylinder, about 12'' x 2" (hydrometer jar),
50c.c. gas-measuring tube, #18 copper wire, 23 cm. long,
evaporating dish, thermometer, barometer.

Material. Yellow phosphorus.

Cantion I TeUow phosphorus should neyer be handled except under water.

(a) Nearly fill a glass cylinder with water. Take a
60 c.c. gas-measuring tube and pour into
it enough water so that the water level is
at a graduation mark when the tube is in-
verted. The tube should be held between
thumb and finger so as not to heat the
inclosed gas, and should be so adjusted
that the water is at the same level outside
and inside.

In a table like that indicated below, re-
cord the volume of the inclosed air and
its temperature (the temperature of the Fig. 6.

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10 LABOBATORT EXEBCI8E8.

water, which should be at the temperature of the room)
Also obtain and record the barometer reading.

Take to the instructor an evaporating dish of water
and obtain a wire with a piece of phosphorus on one
end.^ Keep the phosphorus under water until you reach
your desk and immediately put the wire with the phos-
phorus into the cylinder of water^ letting it rest against
the side of the cylinder (Fig. 6). Now lower the
gas-measuring tube containing the measured volume
of air, over the phosphorus, so that the piece will
be above the middle of the space occupied by the
air.

Note and record the action of the phosphorus and see
whether there is any change in the level of the water
inside the tube. Allow the action to continue over
night.

(J) The next day remove the tube from over the
phosphorus, but still keep the mouth of the tube beneath
the water. Then raise or lower the tube until the water
is at the same level inside and outside.

Read and record the volume of the gas remaining in
the tube. Record the temperature of the water and
the barometric pressure.

Applying Charles' law and Boyle's law, find the vol-
ume which the residual gas would occupy if it were
at the same temperature and pressure as that of the air
first inclosed. The difference between the original vol-
ume of air inclosed and the corrected volume of gas

1 Firat flatten one end of the wire with a hammer, and then trim the
flat end to a point. Cut the phosphorus into pieces about the size of a
small pea (5 mm. diameter). Holding the phosphorus under the water,
thrust the point of the wire into it. Be sure that the phosphorus is
flrmly attached.

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PBEPABATION OF OXYGEN. 1\

remaining, represents the amount of oxygen removed by
the phosphorus. Calculate the percentage of oxygen
in the air. Make all calculations in your note book.

TABLE.

Volume of air taken c.c.

Temperature of air . . ** C.

Pressure of air mm.

Volume of gas remaining in measuring tube .... c.c.

Temperature of gas remaining ® C.

Pressure of gas remaining mm.

Corrected volume of gas remaining c.c.

Volume of oxygen removed by phosphorus .... c.c.

Percentage by volume of oxygen in air %

EXPXSRIMBNT 5.
Preparation of Oxygen by the Decomposition of Potassium Chlorate.

Apparatus. Two test-tubes, delivery tube, rubber stopper,
ring-stand with clamp, Bunsen burner, four 8-oz. wide-mouth
bottles or quick-sealing fruit jars (pint), four glass plates for
wide-mouth bottles, two watch glasses, funnel.

Material. Potassium chlorate, manganese dioxide, filter
paper, splinter.

(a) Mix thoroughly about 8 grams of potassium chlo-
rate and 6 grams of manganese dioxide. Place in a test-
tube provided with a delivery tube. Clamp the test-tube
in a position convenient for heating ; carefully regulate
the heating so as to secure a gentle evolution of the gas.
Do not heat the test-tube sufficiently to make the flame
yellow. Do not remove the burner while the mouth of
the delivery tube is under water.

(J) Collect a test-tubeful of the gas and test with a
glowing splinter. Collect the remainder of the gas in

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12 LABORATORY EXERCISES.

wide-mouth bottles. Cover with glass plates and keep
for Experiment 6.^

(<?) Remove the delivery tube and allow the test-tube
to cool. Nearly fill the test-tube with hot water, close
the mouth of the tube with the thumb, and shake.

Pour the muddy liquid on a moistened filter paper
fitted to a funnel. Collect the clear liquid (^filtrate) in a
test-tube.

Pour a few drops of the filtrate on a watch glass.
Label the watch glass and set it aside so that the liquid
can evaporate.

Remove a small portion of the black residue from the
filter and place on a second watch glass and set aside to
dry.

Shake a little potassium chlorate in a test-tube with
cold water. Place a few drops of the clear solution in
another watch glass, labeled for identification, and set
aside to crystallize.

Which of the original substances does the black residue
resemble? Compare the other two solids remaining on the
watch glass with respect to crystalline form and taste.
Are they the same substance? From which of the original
substances was the oxygen probably derived?

1 If Experiment 6 cannot be performed the same day, the oxygen
should be collected in pint quick-sealing fruit jars.

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FORMATION OF OXIDES. 13

EZPERIBIENT 6.
Formation of Oxides.

Apparatus. Deflagrating spoon, asbestos paper, Bunsen

burner.
Material. Four bottles of oxygen, splinter of charcoal, 15

cm. magnesium ribbon, sulphur, red phosphorus.

(a) Place a thin splinter of charcoal across the bowl of
a clean deflagrating spoon. Heat the end of the splinter
until it glows brightly and immediately lower it into a
bottle of oxygen. Does the charcoal burn with a flame ?
Compare the intensitt/ of the action in oxygen with that in
air. Of what does the gas formed prohahly consist?

(J) Twine a piece of magnesium ribbon around the rod
of the deflagrating spoon, allowing the upper end to pro-
ject slightly. Light the free end and lower the spoon
into a bottle of oxygen. Compare the combustion of the
magnesium with that of the carbon. Compare the action in
oxygen with that in air. What is the appearance of the
oxide of magnesium? Does this seem to be the same
material as that obtained when magnesium was burned in
air (Experiment 1)?

((?) Clean the spoon, line it with asbestos paper (bak-
ing sheet), and put on the paper a small piece of sulphur.
Heat the sulphur until it lights and then lower it into the
bottle of oxygen. Describe the burning of the sulphur
in oxygen. When the mist (principally unburned sul-
phur) has disappeared, very cautiously smell the contents
of the bottle. Name this gas.

(d) Reline the spoon, and place on the asbestos a pinch
of red phosphorus. Light the phosphorus and put it into

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LABORATORY EXERCISES.

a bottle of oxygen. Describe the burning of phosphorus
in oxygen. Is the product a gas or does it consist of fine
solid particles? Name the product.

Make a general statement as to the intensity of burning in
oxygen and in air.

EXPERIMENT 7.
Electrolysis of Water.

Apparatus. Electrolysis apparatus (Fig. 7), pneumatic
trough, magnetic compass, several voltaic cells or other
source of current.

Material. Dilute sulphuric acid, splinter.

Use the apparatus illustrated. Pour water acidulated
with sulphuric acid into the U-tube until the platinum
electrodes are covered.

Fig. 7.

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ELECTROLYSIS OF WATER. 15

Determine with a magnetic compass the direction of
the current through the apparatus.^ The plate through
which the current enters is the anode. The current
leaves the solution at the cathode.

As soon as the water in one of the tubes has been dis-
placed by gas, remove the tube from the pneumatic
trough, keeping it mouth downward. Bring a flame
near the mouth of the tube. Result ?

When the other tube has filled with gas, close it with
the thumb and remove it from the pneumatic trough, in-
verting it at the same time. Insert a glowing splinter
into the gas. Result ?

What gas collects at the anode? Is the same gas
liberated at the cathode ?

Refill the tubes with water and again place them over
the mouths of the delivery tubes. How does the amount
of gas liberated at the anode compare with the amount
liberated at the cathode ?

TTiere is the same amount of sulphuric acid at the end of
the experiment as at the beginning. Where did the gases
come from f

^ If you do not know how to do this, obtain directions from the
instractor.

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16 LABORATORY EXERCISES.

EXPERIMENT 8.

Decomposition of Water by Sodium.

Apparatus. Brass capsule with ramrod to fit, provided with a

wire holder ; dish or pan, test-tube or bottle.
Material. Sodium.

Cantion t The action of eodinm with water is very violent. Avoid danger by
following directions.

Nearly fill a metallic capsule with freshly cut sodium
from which all the crust has been removed. The sodium
mu%t be pressed firmly into the capsule.

Place the capsule in a wire holder, and, holding the
capsule mouth downward^ thrust it under the mouth of an
inverted test-tube or small wide-mouth bottle filled with
water. Control the evolution of the
gas by slightly inclining the capsule.
^^ If careless handling allows the sodium
""^ to escape from the capsule, stand aside.
When the test-tube is filled with gas,
Fig. 8. carry it mouth downward to a fiame.

Result ? This gas is hydrogen. The yellow color is due
to sodium.

Sodium is an element. Where does the hydrogen come
fromf

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PREPARATION OF HYDROGEN. 17

EXPERIMENT 9.
Preparation of Hydrogen by Replacement in an Acid by a Metal.

Apparatus. Wide-mouth bottle (8 oz.), two-hole stopper,
thistle-tube, delivery tube, pneumatic trough, three wide-
mouth bottles (6 or 8 oz.), three glass plates, watch glass,
beaker, ring-stand with large ring, Bunsen burner.

Material. Zinc, dilute sulphuric acid (1 to 6), copper sul-
phate solution.

(a) Use a wide-mouth bottle provided v^rith a two-hole
stopper carrying a thistle-tube and a delivery tube
(Fig. 4). Have three bottles filled with water, standing
inverted in the pneumatic trough. Put about 20 grams
of granulated zinc into the generator, and pour through
the thistle-tube dilute sulphuric acid (1 to 6) until one
fourth of the bottle is filled.

If the action is slow in starting, add a few drops of
copper sulphate solution through the thistle-tube. Ob-
serve the action in the generator. Under no circumstances
add more acid nor in any way interfere with the generator
without consulting the instructor.

(6) Collect the gas in a test-tube. As soon as the test-
tube is filled, carry it mouth downward to a small flame.
Continue to collect and test the gas in this manner until a
portion burns quietly. The hydrogen is now ready to be
collected for Experiment 10.

Fill three bottles with the gas. Leave them standing
on the shelf of the pneumatic trough, or cover with glass
plates and set mouth downward on the desk.

J|@* Proceed to Experiment 10, (a).

((?) Filter a few drops of the liquid in the generating
bottle into a watch glass. Evaporate over steam. (Rest

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18 LABORATORY EXERCISES.

the watch glass on the rim of a beaker one third full of
boiling water.)

Examine the residue.

Is there anything dissolved in the liquid^ and, if so^ what
does the dissolved svistance probably contain ? From what
material does the hydrogen probably come ?

Why did you discard the first portions of the gas? Why
must the joints of the apparatus be perfectly tight f

EXPERIMENT 10.

Properties of Hydrogen.

Apparatus. Glass tube (20 cm.), test-tube, clamp.
Material. Copper oxide (wire form), taper.

(a) Replace the end of the delivery tube with a straight,
dry glass tube, leading to the bottom of a nearly hori-
zontal test-tube containing a little copper oxide (wire
form). Allow the hydrogen to pass into the tube for five
minutes to expel the air. Then heat the tube directly
under the copper oxide.

When the hydrogen passes over the heated copper
oxide, what collects in the cool portion of the tube and
what is left in the heated portion ?

How do you account for the production of these substances ?

What element was removed from the copper oxide by the
hydrogen? A material which acts in this way is called a
reducing agent,

(J) Raise a bottle of hydrogen from your desk and
thrust into it a lighted taper. What happens to the flame
of the taper? What is occurring at the mouth of the
bottle? Slowly withdraw the taper from the bottle.
Explain the result.

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DISTILLATION OF WATER. 19

((?) Hold an inverted bottle of air in one hand. With
the other raise a bottle of hydrogen from your desk and
gradually turn it, mouth upward, directly under the
inverted bottle of air. Bring the mouth of each bottle
near the flame. Results ?

Stand on the desk an uncovered bottle of hydrogen,
mouth upward. At the end of a minute bring it to the
flame.

Explain how these experiments indicate the relative weight
of hydrogen and air.

iS* Now return to Experiment 9, ((?).

BZPERIMISNT 11.
Distillation of Water.

Apparatus. Flask, condenser, and tubes as given below, ring-
stand with one ring, Bunsen burner, additional flask for dis-
tillation, two beakers (150 c.c). seven small beakers or
bottles, watch glass, glass beads.

Material. Solutions of potassium permanganate, phenol-
phthalein, ammonia (concentrated).

On a ring-stand clamp a condenser at such an angle
that the end of its delivery tube just enters the top of a
beaker standing on the table, and so that the upper end
of the condenser is at a height convenient for the distilling
flask. This flask should be supported on wire gauze rest-
ing on a tripod (or ring-stand). The delivery tube of the
distilling flask passes through a one-hole stopper fitting
the tube of the condenser.

Time can be saved in distillations by always having
the distilling flask less than half full and by the use of
glass beads. If these are not available, drop into the

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20 LABORATORY EXERCISES.

distilling flask several pieces of glass tubing about a
centimeter in length.

(a) Pour into the flask 100 c.c. of a water solution of
potassium permanganate. Heat the contents of the flask
to boiling and collect a few centimeters of the condensed
steam (the distillate).

What evidence is there that the water has been puri-
fied by distillation ? Is potassium permanganate volatile
under the conditions of the experiment ?

Suggest a method by which salt water can be converted into
fresh water.

(6) Add a drop of phenolphthalein solution to some
pure water. Result ? To 100 c.c. of pure water add one
drop of concentrated ammonia water and a drop of
phenolphthalein solution. Result ?

Sow can the presence of ammonia in water be shown ?

Prepare another mixture of one drop of concentrated
ammonia water in 200 c.c. of pure water. Pour it into a
clean flask and distil. In each of seven clean beakers or
small bottles, each containing a drop of phenolphthalein,
collect 25 c.c. of the distillate.

What evidence is there that ammonia passes over with
the steam ? Do the first portions of the distillate contain
more or less ammonia than the latter portions ?

Can water be readily purified by distillation from a
volatile impurity like ammonia?

((?) Determine, by evaporation on a watch glass over
steam, whether ordinary water contains non-volatile
impurities.

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SATURATED SOLUTIONS. 21

EXPERIMENT 12.
Saturated Solutions.

Apparatus. Graduate. Erlenmeyer flask (100 c.c), two
beakers (150 c.c), thermometer, ring-stand, with large ring
and asbestos mat, Bunsen burner, mortar and pestle.

Material. Common salt (fine) , potassium nitrate, " hypo,"
cotton wool.

(a) Pour 50 c.c. of water into an Erlenmeyer flask.
Have at hand about 25 grams of fine-grained common salt
(sodium chloride). Add this to the water in the flask, a
little at a time, shaking constantly, until the part last
added is not entirely dissolved. The solution is then
saturated with sodium chloride at the temperature of the
water.

Pour the solution into a beaker and heat slowly. Again
add sodium chloride in small quantities, until the solution
reaches 70** C. Continue adding salt, stirring constantly,
until the solution is saturated at that temperature. Allow
the beaker to cool again to the temperature of the room.
Result?

(J) Grind about 75 grams of potassium nitrate (salt-
peter) to a fine powder in a mortar. Repeat all the opera-
tions of (a), using potassium nitrate instead of sodium
chloride.

How does the amount of sodium chloride required for
saturation at a high temperature compare with that re-
quired at a lower temperature ? In this case what is the
relation between temperature and solubility? Compare
the effect of the temperature on the solubility of potassium
nitrate udth its effect on the solubility of sodium chloride.
The majority of salts resemble potassium nitrate rather

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22 LABORATORY EXERCISES.

than sodium chloride in the effect of temperature on their
solubility.

((?) In a clean Erlenmeyer flask heat 50 grams of
"hypo" (sodium thiosulphate) with 10 c.c. of water
until a solution results. Plug the mouth of the flask
with cotton and allow it to stand quietly until it cools to
room temperature. JRenEiove the cotton and drop a crystal
of hypo into the solution. Observe closely and describe.
Feel of the lower part of the flask. Result?

What change has been produced by dropping in the
crystal ? A solution which behaves as the hypo solution
does at room temperature is said to be supersaturated at
that temperature. Can you suggest any reason for closing
the mouth of the flask with cotton? (Class discussion.)

EXPERIMENT 13.
Water of Crystallization.

Apparatus. Horn pan balance, two watch glasses (3 in. ) , shot
for counterpoise, eight test-tubes, test-tube rack, burner.

Material. Crystallized sodium sulphate, copper sulphate,
potassium chlorate, zinc sulphate, barium chloride, potassium
sulphate, potassium nitrate, and alum.

(a) Place a small watch glass on the pan of a balance and
then add enough crystallized sodium sulphate to counter-
poise the weight placed by the instructor in the other pan.
Set aside for a half hour and record any changes in appear-
ance. Again place on the balance. What does the change
in weight indicate?

(6) Heat a few crystals of sodium sulphate carefully in
a dry test-tube. What collects on the walls of the test-

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WATER OF CRYSTALLIZATION. 23

tube? To what, then, is the change in weight noticed in
(a) probably due?

(e?) In another test-tube gently heat a crystal of blue
vitriol (copper sulphate) over a small flame until no
further change occurs. What three important effects
have been produced?

Dissolve the residue in the bottom of the tube in a few
drops of hot water. Pour the solution on a watch glass
and allow it to stand.

Compare the final product with the original substance*
What action took place when the copper sulphate was
heated? What happened when the residue was dissolved
and allowed to cool ?

(d) In separate dry test-tubes gently warm a few crys-
tals of potassium chlorate, zinc sulphate, barium chloride,
potassium sulphate, potassium nitrate, and alum. Record
the results in the following tabular form :

Substance Changes in appearance Amount of deposit Appearance
heated of substance in cool portion of residue

of tube

Do all crystalline substances contain water of crystalli-
zation? Illustrate. Compare the substances used with
reference to the amounts of water of crystallization which
they contain. Suggest a reason for the alurrCs becoming
liquid at a much lower temperature than the potassium
nitrate.

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24 LABORATORY EXERCISES.

EXPERIMENT 14 A.

Equivalent of Magnesium.

Apparatus. Gas-measuring tube, 50 c.c, battery jar, ther-
mometer.
Material. Magnesium, concentrated hydrochloric acid, thread.

The data for this experiment should be tabulated in
your note book as indicated below.

Pour about 6 c.c. of concentrated hydrochloric acid
into a gas-measuring tube. Fill the remainder of the
tube with water, taking care not to mix the acid and
water ; the heavier acid will remain at the bottom.

Roll a weighed piece of magnesium, weighing about
0.045 gram,^ into a loose coil somewhat smaller than the
inside diameter of the tube. Pass a thread through the
loop of the coil, and tie.

Put the magnesium into the measuring tube, holding
the thread so that it will not sink. Close with the thumb
and invert the tube into a battery jar of water, resting it
against the bottom, so that the thread will be caught
between the tube and the bottom of the jar, allowing
the magnesium to rise not quite to the graduation in
the tube.

The heavier acid will flow down and react with the
magnesium :

magnesium + hydrochloric acid — >-

hydrogen + magnesium chloride

When the action has ceased (all the metal being dis-
solved), adjust the levels, and read the volume of hydro-
gen obtained. Record the temperature of the liquid in

1 Weigh a strip of magnesium ribbon several meters in length and cut
off a piece weighing the required amount.

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EQUIVALENT OF MAGNESIUM. 26

the jar and the barometric pressure. Correct the pressure
for aqueous tension (use table on page 126).

Reduce the volume to standard conditions. The weight
of a liter of hydrogen under standard conditions is 0.09
gram. Calculate the weight of the hydrogen evolved.
Then determine what weight of magnesium is required
to liberate one gram of hydrogen. What name is given to
this weight?

Make all calculations in your note book.

TABLE.

Weight of magnesium taken

Volume of hydrogen obtained

Temperature of hydrogen

Barometric pressure

Aqueous tension

Pressure of hydrogen

Volume of hydrogen under standard conditions . . •

Weight of hydrogen

Equivalent of magnesium

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26 LABORATORY EXERCISES.

EXPERIMENT 14 B.

Equivalent of Sodium.

Apparatus. Metallic capsule and holder, horn pan balance,
weights, 16-oz. bottle, graduate, pneumatic trough, glass plate.
Material. Sodium.

Caution I Remember that the action of BOdium with water is very violent.
The data for this experiment should be tabulated in the
note book as indicated below,

(a) Weigh a metallic capsule which is clean and dry, and
record its weight. Nearly fill the capsule, as in Experi-
ment 8, with freshly cut sodium freed from any adhering
crust. Wipe off any oil with filter paper. Weigh the
capsule again at once and record the weight.

(6) Fill the wide-mouth bottle with water and measure
its capacity by pouring the water into a graduate.
Record.

((?) Then fill the bottle with water and invert it in the
trough. Place the metallic capsule in its holder. Raise
the bottle in the trough with the left hand. Take the
holder in the right hand and incline it so that the open
end of the capsule will be downward. Keeping the open
end downward^ thrust the capsule under the mouth of the
bottle. Control the evolution of the hydrogen by sKffhtly
inclining the capsule.

(rf) When the action ceases, adjust the bottle so that
the liquid on the inside is level with that outside. Close
the mouth of the bottle with a glass plate, remove it from
the trough, and set it on the desk, mouth upward. Pour
the liquid now in the bottle into a graduate and record its
volume.

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EQUIVALENT OF SODIUM. 27

Record the temperature of the liquid in the trough
and the barometric pressure. Correct the pressure for
aqueous tension (use table on page 126).

Reduce the volume to standard conditions. The
weight of one liter of hydrogen at standard conditions is
0.09 gram. Calculate the weight of hydrogen evolved.
Then determine what weight of sodium is required to
liberate one gram of hydrogen. What name is given to
this weight f

Make all calculations in your note book.

TABLE.

Weight of capsule and sodium

Weight of capsule

Weight of sodium taken

Capacity of bottle

Volume of liquid left in the bottle

Volume of hydrogen obtained

Temperature of hydrogen

Barometric pressure

Aqueous tension

Pressure of hydrogen

Volume of hydrogen under standard conditions . . •

Weight of the hydrogen

Equivalent of sodium • • •

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LABORATORY EXERCISES.

EXPERIMENT 15.
Preparation and Properties of Chlorine.

Apparatus. Flask, four wide-mouth bottles (6 oz.), with two-
hole rubber stoppers, eight glass bends, four rubber con-
nectors. ring-stand with large ring, pan of water, Bunsen
burner, four glass plates or watch glasses (Syracuse form),
one hydrogen generator for the class.

Material. Concentrated hydrochloric acid, manganese diox-
ide, taper, colored cloth, powdered antimony.

Caation I Chlorine is a poisonous gas. Do not inhale it. Inhaling ammonia
or alcohol will counteract some of its effects.

Arrange apparatus as in Figure 9.
amount of water into the fourth bottle.

Pour a small

(a) Place in the flask 15 c.c. of concentrated hydro-
chloric acid and add about 8 grams of granular manganese

dioxide. Rotate the flask
so as to mix its contents,
then replace the stopper.

Heat the water in the
dish under the flask to
boiling. Describe the
action in the generator.

Hold a piece of white
paper behind the first
bottle. What is the

How can you tell when the bottle

Fig. 9.

color of chlorine?
is filled with gas?

When the bottles are filled with chlorine, withdraw
the flame. Keep the gas for use in ((?), (c?), and (e).

(J) Is chlorine soluble in water ? Give a reason for
your answer.

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PREPARATION AND PROPERTIES OF CHLORINE. 29

((?) The instructor At this point should introduce a
jet of burning hydrogen into a bottle of chlorine.

What compound is formed when hydrogen burns in
oxygen? What is formed when hydrogen burns in
chlorine?

Lower a lighted taper into a bottle of chlorine. The
taper is composed of compounds containing hydrogen
and carbon. Which of these elements is liberated when
the candle burns in chlorine ?

(rf) Place a piece of dry colored cloth in one bottle of
chlorine and a piece of wet cloth in another. Cover
the mouths of the bottles with glass plates. What must
be the condition of the cloth to be bleached by chlorine ?
Explain ike bleaching of cloth by chlorine. (^ClasB dis-
cussion^.

(e) Sprinkle a pinch of powdered antimony into the
bottle of chlorine from which the dry cloth has been
removed. Result?

Hydrochloric acid is a compound of hydrogen and chlorine.
With what does the oxygen of the manganese dioxide combine ?

What is your conclusion as to the chemical activity of
chlorine?

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30 LABORATORY EXERCISES.

EZPERIBCBNT 16.
Preparation and Properties of Hydrochloric Acid.

Apparatus. Flask (250 c.c), with stopper carrying thistle-
tube and delivery tube, ring-stand with one ring and wire
gauze (asbestos center), Bunsen burner, two test-tubes, wide-
mouth bottle, dish of water.

Material. Sodium chloride, sulphuric acid (2 to 1), blue
litmus paper, magnesium, zinc.

(a) Pour about 20 c.c. of sulphuric acid (2 to 1) into
a flask supported on an asbestos mat on a ring-stand,
and add about 10 grams of sodium chloride. Gently ro-
tate the flask so as to mix the acid with the chloride.
Close the flask with a stopper carrying a thistle-tube and
a delivery tube arranged for the collection of gas by
downward displacement in a dry test-tube. If necessary,
heat the flask with a small flame. Describe the action in
the generator.

Of what elements is hydrogen chloride composed? Where
does the hydrogen come from? The chlorine? Why was
sulphuric acid selected? QClass discussion.^ What does
the method of collection show concerning the weight of hydro-
gen chloride relative to air?

(J) Fill a dish with water and set it on the table.
Take the test-tube of gas collected, close its mouth tightly
with the thumb, invert the test-tube, and hold its mouth
below the surface of the water. Remove the thumb.
Result? Explain why the gas is not collected over water.

Close the mouth of the test-tube with the thumb and
remove it from the water. Moisten a piece of litmus
paper with the liquid contained in the test-tube. Result ?
This effect is typical of the water solution of acids. The

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PROPERTIES OF HYDROCHLORIC ACID. 81

solution in the reagent bottle marked " hydrochloric acid "
is also prepared by dissolving hydrogen chloride in water.

(c) Pour not more than 10 c.c. of water into a wide-
mouth bottle. Place the mouth of the delivery tube
within half a centimeter of the surface of the water in the
bottle. Heat the flask with a small flame for at least ten
minutes. While doing this, occasionally look through the
water in the bottle horizontally. Is the solution of hydro-
gen chloride formed heavier or lighter than water?

(d) Pour half of the solution into a test-tube and drop
into it a strip of magnesium. Result? Bring a flame
near the mouth of the tube. Result ?

(e) Place a piece of zinc in another test-tube and pour
the hydrochloric acid remaining in the wide-mouth bottle
upon it. Test the gas with a flame. Results?

What ntbatance is liberated when a metal reacts with
hydrochloric acid? Magnesium and zinc are elements.
Where does the substance liberated come from? What be-
comes of the metal ? Hydrochloric acid is a typical acid.

What properties^ then^ characterize acids ?

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32 LABOBATOBY EXEBCI8E8.

EXPERIMENT 17.
Test for a Chloride.

Apparatus. Six test-tubes, test-tube rack.

Material. Dilute hydrochloric acid, dilute nitric acid, solu-
tions of silver nitrate, ammonium hydroxide, sodium phos-
phate, potassium oxalate; unknowns.

(a) To a little hydrochloric acid in a test-tube add sil-
ver nitrate solution. The substance which separates out is
silver chloride. Any solid which thus separates out of a
clear liquid is known as a precipitate.

Describe the silver chloride precipitate as to color and
appearance.

When most of the precipitate has settled, pour off the
liquid above it. Nearly fill the test-tube with water, shake,
and allow the precipitate to settle. Pour off the liquid as
before.

Divide the precipitate equally between three test-tubes.

(J) Add dilute nitric acid to one portion of the silver
chloride. Record result in a table like that given below.

Try the effect of nitric acid on this precipitate.

(<f) Take a little of a solution of potassium oxalate and
add to it silver nitrate solution. Result ?

Try the effect of nitric acid on the precipitate.

How can you distinguish a precipitate which a chloride
gives with silver nitrate from precipitates given hy an oxalate
or a phosphate toith silver nitrate f

Verify your opinion by testing a solution of sodium
chloride.

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TEST FOR A CHLORIDE.

{e) Take another portion of the silver chloride precipi-
tate and determine whether it is soluble in ammonium
hydroxide.

Look at the third portion of the silver chloride and see
what effect light has upon it. If doubtful, stand the test-
tube containing the precipitate in direct sunlight.

Make a statement which mil give three characteristic prop-
erties by which you could identify a precipitate of silver
chloride.

What tests would you make to prove that a solution given
you contained a chloride?

(/) Apply to the instructor for an unknown solution..
Test it for a chloride, writing results obtained in each
step. State your opinion as to whether the unknown
solution contains a chloride, and give reasons for your
belief.

Solution Takkn.

Effbot of

ADDING
SiLTKB NlTRATK.

EFFECT ON PRECIPITATE OF

NiTBic Acid. Ammonium Htdrozidk. Sunlight.

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LABORATORY EXERCISES.

EXPERIMENT 18.
Weight of a Liter of Oxygen.

Apparatus. Horn pan balance, weights, test-tube with rubber
stopper carrying a delivery tube, 4 in. U-tube with one-hole
rubber stoppers, and delivery tube, pneumatic trough, 2-liter
bottle (acid bottle), glass plate, graduate, ring-stand, clamp.

Material. Well dried potassium chlorate, dry and powdered
manganese dioxide (C.P. quality gives a more accurate
result), granulated calcium chloride.

(a) Arrange the apparatus as in diagram (Fig. 10).

The U-tube should contain
granulated calcium chloride.
Mix about 6 grams of
thoroughly dried manganese
dioxide with 8 grams of
potassium chlorate. (C.P.
quality gives a more accurate
result.)

Put the mixture into a dry
test-tube, and above the powder place a loose plug of
glass wool.

Collect the gas. in a bottle of about 2 liters' capacity
(acid bottle).

Tabulate the data in your note book as indicated by the
table on page 36.

(J) Weigh to a centigram on a balance the test-tube
containing the mixture, the connecting tube with its two
stoppers, and the U-tube. Record the weight. Clamp the
apparatus in place, and adjust the rubber stopper carry-
ing the; delivery tube leading to the pneumatic trough.

The test-tube should be inclined at a slight angle so as

Fig. 10.

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WEIGHT OF A LITER OF OXYGEN. 35

to permit the spreading of the black mixture along the
tube. Heat with a small flame, beginning at the top, and
gradually working downward.

Carefully regulate the heat so that you can always
count the bubbles of the oxygen. Continue until the
bottle is nearly full, or as long as time will allow.

When the oxygen has ceased to pass over, at once
remove from the U-tube the delivery tube with its at-
tached stopper. Allow the apparatus to cool.

((?) While waiting for this, measure the volume of the
oxygen. Lower the large bottle in the trough so as to
adjust the water levels to the same height, close the
mouth of the bottle with a stopper or a glass plate, and
remove from the trough, inverting the bottle as you do so.

Find the volume of the oxygen by the amount of water
necessary to fill up the bottle, pouring water into the
bottle from a graduate.

(d) When the test-tube feels barely warm to the hand,
weigh, as before, the test-tube, connecting tube, and U-
tube. Record weight. The loss of weight is the weight
of the oxygen evolved.

Record the barometric pressure and the temperature of
the water in the pneumatic trough. This is approximately
the temperature of the gas.

Calculate the volume of the oxygen under standard
conditions.

Using the weight of oxygen as found, calculate the
weight of a liter of oxygen under standard conditions.

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LABORATORY EXERCI8ES.

DATA.

Weight of generating and drying tube before heating .
Weight of generating and drying tube after heating .

Weight of oxygen evolved

Volume of oxygen evolved under conditions of experiment ,

Temperature of oxygen

Barometric pressure

Aqueous tension

Pressure of oxygen

Volume of oxygen under standard conditions

Weight of one liter of oxygen under standard conditions

EXPERIMENT 19.

Apparatus. Evaporating dish, glass plate (4x4), stirring
rod, six test-tubes, beaker, ring-stand with one ring, Bunsen
burner.

Material. Metallic sodium, filter paper, litmus paper, calcium
oxide, sodium hydroxide solution (about 8 grams to 100 c.c.
of water), potassium hydroxide solution (about 1 1.2 grams to
100 c.c. of water), hydrochloric acid (1 to 4), sulphuric acid
(1 to 10).

(a) Take a freshly cut piece of sodium the size of a
pea and completely remove the adhering oil v^rith filter
paper. Hold a square of glass vertically (to protect the
face) in front of an evaporating dish containing about 10
c.c. of water. Place the sodium on the water. Results ?

Determine the action of the solution on litmus and
rub some of it between the fingers. Results ? Evaporate
part of the solution to dryness. The substance left in the
dish is sodium hydroxide. Describe its appearance.

Write an equation for the reaction.

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BASES. 37

(6) Place a gram of quicklime (calcium oxide, CaO) in
a test-tube and add 1 c.c. of water. Warm the mixture
until the water begins to boil; remove the tube from the
flame and see if there is an action between the quicklime and
the water. If not, continue the warming until an action
begins and continues without the further addition of heat.

How does the substance formed compare with the orig-
inal lime ? This new substance is slaked lime (calcium
hydroxide, Ca(0H)2). Write an equation for its forma*
tion.

Add water to the slaked lime, shake thoroughly, and
allow the solid to settle. Pour off the clear liquid into
another test-tube. Determine the action of this solution
on litmus.

What common property have the solutions of sodium
hydroxide and calcium hydroxide? This is one of the
characteristic properties of the solutions of metallic
hydroxides (bases).

(c) To 5 c.c. of a moderately concentrated solution of
sodium hydroxide add about an equal quantity of dilute
hydrochloric acid. Is there any evidence of chemical
action ?

In a similar way mix solutions of potassium hydroxide
and dilute sulphuric acid ; potassium hydroxide and
dilute hydrochloric acid. Results in each case ?

What second property is possessed in common by the
bases ?

(d) The mixing of an acid solution and a base solution
in the exact quantities for complete reaction with each
other is termed neutralization.

How could you use litmus to indicate the exact neutral-
ization point ?

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38 LABORATORY EXERCISES.

Make a few cubic centimeters of an exactly neutral
mixture of sodium hydroxide and hydrochloric acid solu-
tions. Evaporate about 6 c.c. of it to dryness. Taste the
residue. How does the residue compare in appearance with
that obtained in (a)?

EXPERIMENT 20.
Determination of the Concentration of a Solution by Titration.

Apparatus. Two burettes, beaker or Erlenmeyer flask,
stirring rod, ring-stand with two clamps.

Material. Solutions of hydrochloric acid (preferably fifth-
normal), sodium hydroxide, and phenolphthalein (made by
dissolving 1 gram of phenolphthalein in 100 c.c. of 50 %
alcohol). A normal solution of an acid contains 1 gram
of replaceable hydrogen per liter. A normal solution of a
base contains 17 grams of replaceable hydroxyl per liter.

Fill one burette above the zero mark with a solution of
hydrochloric acid of known concentration. Draw off
enough of the acid to remove the air bubbles from the tip
and bring the meniscus to the graduated portion of the
burette.

In reading a burette, read from the bottom of the me-
niscus, using care to have the eye, graduation, and lowest
part of the meniscus on the same level.

Similarly, fill and adjust another burette with a sodium
hydroxide solution whose concentration is to be deter-
mined. Record the readings of both burettes in a table
like that given below.

Allow about 10 c.c. of the sodium hydroxide solution to
flow from the burette into an Erlenmeyer flask or into a
beaker, and add a drop or two of some indicator, e,ff. a
solution of phenolphthalein or of litmus.

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SOLUTION BY TITRATION.

What color is produced when phenolphthalein is added
to an alkaline solution? To an acid solution? Why is
phenolphthalein called an indicator?

Allow the hydrochloric acid to flow a few drops at a
time, with stirring or shaking after each addition, into
the sodium hydroxide solution until the reddish tinge
just disappears. Now add the sodium hydroxide solution,
a drop at a time, until a reddish tinge is produced ; then
determine whether a drop of acid will make the solution
colorless. If it will not, continue in the manner indicated
until a reversal of color is produced by a drop or two of
acid or of base.

Read the burettes to tenths (or hundredths if directed)
of a cubic centimeter and record the final readings in the
table. Make three separate determinations, washing out
the flask after each determination.

TABLE.

DSTXBMIHATIOir.

Aver.

Reading of acid burette when neutralization

is complete
Reading of acid burette before neutralization
Volume of hydrochloric acid used

Reading of base burette when neutralization

is complete
Reading of base burette before neutralization
Volume of sodium hydroxide used

. • .

...

Calculate the weight of hydrogen chloride in the average
volume of the acid used. From the equation:

NaOH + HCl— ^ + ,

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LABORATORY EXERCISES.

calculate the weight of the sodium hydroxide needed to neur
trcUize the hydrogen chloride. From the average volume
of sodium hydroxide used^ calculate the weight of sodium
hydroxide in 1 c,c. of the solution tested. Calculate the
weight of sodium hydroxide in one liter of this solution.

Proceeding as above, you could now make use of the
sodium hydroxide solution, whose concentration is known,
to determine the concentration of a solution of sulphuric
or other acid. The table and calculations would be
similar to those already used.

EXPERIMENT 21.
Flame Tests.

Apparatus. Bunsen burner, three cobalt glass plates. Each
solution should be contained in a small bottle or vial with a
cork stopper, through which passes a glass tube carrying a
platinum or iron wire.

Material. Solutions of salts of lithium, sodium, potassium,
calcium, strontium, and barium ; mixed solution of sodium
and potassium salts ; unknowns.

(a) Test salts of lithium, sodium, potassium, calcium,
strontium, and barium. Hold one platinum wire at a
time in the hot outer portion of a Bunsen flame. Note
and record result in tabular form in each case. Be
careful to replace each wire in its special bottle.

TABLE.

SoLunoK.

Color op Flamb.

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FLAME TESTS. 41

The characteristic coloration of the flame in each case
is due to the vapor of the metal.

(J) Observe the color of a sodium flame through three
thicknesses of cobalt glass. In a similar way examine
the potassium flame through the cobalt glass. Can you
see the sodium flame through the cobalt glass ? What is
the effect of the cobalt glass on the potassium flame ?

Take a solution of a mixture of sodium and potassium
salts, and, without using the cobalt glass, note the flame
color. Why are not both the characteristic colors seen ?

Use the cobalt glass with the mixed solution and find
which flame can be recognized. What is the use of the
cobalt glass in making flame tests of mioctures of sodium and
potassium salts ?

What use might be made of the flame tests in analytical
work?

Test an unknown salt obtained from the instructor.

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42 LABORATORY EXERCISES.

EXPERIMENT 22.

Preparation of an Acid Salt.

Apparatus. Graduate, two beakers, stirring rod, ring-stand with
large ring, wire gauze with asbestos center, Bunsen burner.

Material. Solutions of sulphuric acid (1 to 5) and sodium
hydroxide (20 grams to 100 c.c. of water) ; litmus paper.

(a) Take 25 c.c. of dilute sulphuric acid and neutralize
it with sodium hydroxide solution.

Write the equation.

Evaporate two thirds of the water in the neutral
solution and set the remainder aside to crystallize.

(J) In another beaker again neutralize 25 c.c. of dilute
sulphuric acid with sodium hydroxide. Add to this
neutral solution another 25 c.c. of sulphuric acid. Evap-
orate the solution to one fourth of the volume and set
aside to crystallize.

Compare the crystals obtained with those obtained in
(a) as to size and general form. Do they appear to be
crystals of the same substance ?

There are two sodium sulphates: normal sodium sul-
phate, NagSO^, and acid sodium sulphate, NaHSO^.
Which one was formed in (a) f Write the eqtuition for the
formation of the other in (J).

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PREPARATION OF SODIUM CARBONATE. 43

EXPERIMENT 23.
Preparation of Sodium Carbonate.— Solyay Process.

Apparatus. Bottle (16 oz.) with two-hole stopper carrying
a thistle-tube and doubly bent delivery tube, three test-tubes,
one provided with a one-hole stopper and a delivery tube,
ring-stand, clamp, "Bunsen burner.

Material. Marble chips, concentrated hydrochloric acid,
concentrated ammonium hydroxide solution, C.P. sodium
chloride, lime-water, sodium bicarbonate, filter paper.

(a) Preparation of sodium bicarbonate.

Saturate. 20 c.c. of a mixture of one part ammonium
hydroxide solution and two parts water with sodium
chloride. Pass carbon dioxide into the ammoniacal brine
until it is saturated (or until the bicarbonate separates).

The carbon dioxide is generated by treating marble
with hydrochloric acid solution. Just cov6r the marble
with water; add one fourth as much acid. Add more
acid as needed. The action should be continued slowly
for a long time (15 to 20 minutes) rather than violently.

Filter off the precipitated bicarbonate and dry by press-
ing it between filter paper.

What is its appearance ? Taste ?

Complete the equations:

CaCOg + HCl — ^C02 + CaCla +

NH3 + HjO + CO2— ^NH^HCOj

NaCl + — ^NaHC08 + NH4CI

Commence (J) while waiting for the first part to finish.

(5) Conversion of the sodium bicarbonate into sodium
carbonate.

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44 LABORATORY EXERCISES.

Place a couple of grams of sodium bicarbonate in a
test-tube, provided with a stopper and a delivery tube, lead-
ing into a test-tube containing lime-water, Ca(OH)2.

Heat the bicarbonate without using sufficient heat to
color the flame yellow. What collects on the sides of the
test-tube ? The solid left in the test-tube is sodium car-
bonate.

How does the taste of the sodium carbonate compare
with that of the sodium bicarbonate ?

What produced the change in the lime-water f

Complete the equations :

NaHCOg (heated)— >.Na2C03 + ...... +

Ca(OH)3 + COj— ^CaC08 +

EXPERIMENT 24.

Determination of Water of Crystallization.

Apparatus. Ring-stand with one ring, pipe-stem triangle,
porcelain crucible, horn pan balance, weights, Bunsen burner.
Material. Crystallized barium chloride.

Barium chloride is the salt selected for this determina-
tion because it is easily obtained pure and is neither efflo-
rescent nor deliquescent.

Weigh a porcelain crucible on the horn pan balance.
Then put into the crucible about two grams of crystallized
barium chloride, and weigh carefully the crucible and its
contents. Record all weights in a tabular form like that
given below.

Support the crucible on a pipe-stem triangle so adjusted
in height that the bottom of the crucible is a short dis-
tance above the top of the inner cone of the Bunsen flame.

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WATER OF CRYSTALLIZATION. 46

Heat the crucible very gently at first — too rapid heating
may cause the water of crystallization to be driven off ex-
plosively, carrying along with it some of the salt. Grad-
ually heat the crucible to the full intensity of the flame.

After fifteen minutes of this strong heating, slowly cool
the crucible, weigh, and record the weight. Repeat the
heating and weigh again. Continue this process until you
get two successive weighings with the same result. This
is called "heating to constant weight." What does this
constant weight show about the water of crystallization ?

From your data ascertain (1) the weight of the crystal-
lized barium chloride, (2) the weight of the anhydrous
barium chloride left after heating. The "anhydrous" salt
is the crystallized salt minus its water of crystallization.

You know the weights in grams of two substances [(1)
and (2)] . Calculate from the table of atomic weights (page
121) the molecular weight of one of them, i.e. the anhydrous
barium chloride, BaClg. Therefore you have the three
quantities necessary to form a proportion where the gram
weights have the same ratio as the molecular weights.
What will a;, the fourth term, represent ?

What part of the molecular weight of the crystallized salt
is water f How many molecules of water does this mean ?
Write the formula of crystallized barium chloride.

Calculate the per cent of water of crystallization in crys-
tallized barium chloride.

DATA.

Weight of crucible + crystallized barium chloride

Weight of crucible empty

Weight of crystallized barium chloride

Weight of crucible + barium chloride after ^r*^ heating
Weight of crucible + barium chloride after second heating .

Weight of crucible empty

Weight of anhydrous barium chloride

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46 LABORATORY EXERCISES,

EXPERIMENT 25.
Forms of Sulphur.

Apparatus. Two test-tubes, watch glass, filter paper, folded
paper or other test-tube holder, dish of water, magnifier,
Bunsen burner.

Material. Roll sulphur, carbon disulphide.

(a) Place a very small piece of roll sulphur in a test-
tube containing about 2 c.c. of carbon disulphide, and
shake a few times. Pour the solution into a watch glass
and set aside to evaporate, but not near a flame.
Make an accurate drawing of two or three crystals as
seen under a magnifier.

(J) Fill a test-tube half full of sulphur. Have ready a
dish of water and a folded filter paper. Melt the sulphur.
During the melting the tube should be inclined above a
small flame and rotated until the sulphur is melted. The
melted sulphur should not be darker than a pale yellow
color.

Pour the melted sulphur into the folded filter, which is
held by the edge. Watch the sulphur as it cools. As
soon as several crystals have formed from the edge to
the center of the surface^ pour into the water that part of
the sulphur still in the melted condition and immediately
unfold the filter. Draw two or three of the crystals as
seen under a microscope.

Examine the crystals after a few days. Result ?

(c) Use the same test-tube as in part (J) and fill it
one third full of sulphur. Heat, tilting the tube occa-
sionally, and note the successive changes in the color and
in the consistency of the sulphur.

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PREPARATION OF METALLIC SULPHIDES. 47

When the sulphur is boiling, pour cautiously into a
dish of water. Note what appears on the surface of the
water. Examine the cooled sulphur. Note its color. Is
it hard or soft ? Elastic or brittle ? Keep it for several
days and note any change.

Upon what does the form that sulphur assumes depend?
What form is stable at ordinary temperatures?

EXPERIMISNT 26.
Preparation of Metallic Sulphides.

Apparatus. Three test-tubes, ring-stand with one ring, and
wire gauze with asbestos center, Bunsen burner.

Material. Powdered sulphur, thin copper foil or copper wire
=tt:30, fine iron filings, zinc dust.

(a) Heat, in a test-tube, a small pinch of sulphur to
boiling. Insert a strip of copper. Result ?

(J) Mix thoroughly one part of powdered sulphur with
two parts of fine iron filings. Place them in a test-tube.
Warm the lower end of the tube just sufiBciently to color
the flame yellow. When action begins, withdraw from
the flame. Result ?

(<?) Mix thoroughly one pinch of sulphur with an equal
bulk of powdered zinc. Placing the mixture in a conical
pile on asbestos, and holding the burner at arm^s lengthy
cautiously ignite the pile from above. Result ?

Sow does the action of these metals with sulphur compare
with their action with oxygen ?
Complete the equations :

Fe + S— ^

Cu + S— ^

Zn+S— ^

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48 LABORATORY EXERCISES.

EXPERIMENT 27.
Preparation and Properties of Hydrogen Snlphide.

Apparatus. Five test-tubes, stopper and delivery tube to fit

one of the test-tubes.
Material. Iron sulphide, dilute hydrochloric acid, solutions of

copper sulphate, cadmium nitrate, and hydrogen peroxide.

litmus paper.

(a) In a test-tube provided with a stopper and a de-
livery tube place some iron sulphide and cover with dilute
hydrochloric acid.

Collect the gas by downward displacement in a dry
test-tube, remove the delivery tube, and light the gas in
this test-tube.

What products are formed when the gas burns in this
way? How do you identify them? What does this show
concerning the composition of the gas? ^

(6) If the gas in the test-tube burned quietly^ light
the gas at the end of the delivery tube.

Are the products formed the same as before ? Why ?

(<?) Place the end of the delivery tube in a test-tube
half filled with water and let the gas bubble through the
water two or three minutes. How does the solution
taste ? What effect has it on litmus ?

Using a small portion of the solution of hydrogen sul-
phide in each case, add a few drops of:

(1) a solution of copper sulphate;

(2) a solution of cadmium nitrate.

((?) Allow the gas from the generator to bubble through*
a solution of hydrogen peroxide until a decided effect is
obtained. Results ?

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PREPARATION OF SULPHUR DIOXIDE. 49

Complete the equations :

FeS + HCl — »- .

....

. +

HjS + CuSO< — >- .

....

H3S + CdCNOg), -^ .

....

. +

HjS + HjOj —*■ .

. +

EZFBRIBIBNT

28.

Preparation of Salphor Dioxide

Apparatus. Ring-stand with two rings, wire gauze with
asbestos center, Bunsen burner ; 250 c.c. flask with stopper
carrying thistle-tube and doubly bent delivery tube ; two
wide-mouth bottles, with rubber stopper to fit one of them ;
two glass bends and rubber connection ; two test-tubes,. with
corks to fit ; glass plate.

Material. Copper (turnings or fine copper wire), concentrated
sulphuric acid.

Caution ! The gas is poisonous. Do not inhale directly.

(a) Support the flask on the wire gauze and provide
with a stopper carrying a thistle-tube and a doubly bent
delivery tube reaching halfway down into a wide-mouth
bottle (safety bottle).

Put about 5 grams of copper turnings into the flask, and
add through the thistle-tube enough concentrated sul-
phuric acid to cover the copper.

Attach delivery tubes to the safety bottle so that the
gas will be led nearly to the bottom of the second wide-
mouth bottle (Fig. 11).

Heat the flask with a imall flame, and if white fumes
appear in the flask above the liquid, moderate the beat.

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LABOBATORT EXERCISES.

Describe the action in
the generator. Remove
the bottle when it is
filled and cover it with
a glass plate. In the
same way, fill a dry
test-tube with the gas,
cork, and set it in the
rack.

(J) Fill a test-tube
half full of water, and
place the end of the de-
livery tube just below
the surface of the water.
Keep it there for five
minutes.

Caotion ! If the water begins to rise in the delivery tube, increase heat im^
mediately.

Remove the delivery tube from the water, extinguish
the flame, and allow the flask to cool in position.
Cork the test-tube and place it in the rack.

What gas is vsucdly liberated when an acid acts on a
metal ? Since hot^ concentrated sulphuric acid acts as an
oxidizing agents explain why we do not get this gas here.
From which of the original materials is the sulphur dioxide
derived f

Complete the equation:

Cu + H2SO4— ^CuSO^ + -h

Use the gas collected and the solutipn in the corked
test-tube, as directed in Experiment 29.

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PROPERTIES OF SULPHUR DIOXIDE. 51

EXPERIMENT 29.
Properties of Sulphur Dioxide.

Apparatus. Dish of water, test-tube.

Material. Sulphur dioxide gas and solution from Experiment
28. flower (preferably a pink), litmus paper, barium chloride
solution, dilute sulphuric acid, dilute hydrochloric acid, potas-
sium permanganate solution (1 to 1000).

To smell a gas, remove the cover from the bottle.
Holding the bottle at some distance from you, waft the
gas toward the nostrils with the hand.

(a) Has sulphur dioxide an odor ? How does its weight
compare with that of air ? GHve your reason.

(J) Take the test-tube of gas which you have collected,
add a little water, close the mouth of the tube tightly with
the thumb, and shake. Keeping the thumb tightly in
position, place the mouth of the tube below the surface of
some water in a dish and remove the thumb. Result ?
What does this show f

(<?) Place a moist flower in the bottle of gas, cork, and
allow it to stand. Result ?

((f) Test the water solution of sulphur dioxide with
red and blue litmus. Results ? Is the water solution of
sulphur dioxide acid or basic? A chemical compound which
combines with water to form an acid is an acid anhydride.
Sulphur dioxide is such a substance. Complete the following
equation: H,0 + SOa-^

(e) To 5 c.c. of barium chloride solution in a test-tube,
add a few drops of dilute sulphuric acid and 6 c.c. of dilute
hydrochloric acid. Result ? The formation with barium

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62 LABORATORY EXERCISES.

chloride of a white precipitate, which is insoluble in dilute
hydrochloric acid, is the test for sulphuric acid (or other
soluble sulphate). Complete the eqimtion:

HaSO^ + BaCla— ^ +

Add 5 c.c. of the water solution of sulphur dioxide to
an equal amount of a dilute solution of potassium perman-
ganate, KMnO^. Result? To the solution obtained, add
a few drops of a solution of barium chloride and 5 c.c. of
dilute hydrochloric acid. Result ?

Sow does the formula of the product formed in (d) differ
from that of stdphurie acid? What is the name of the pro-
cess by which sulphurous acid is converted into sulphuric
acid f Has the permanganate caused this change in the sul-
phurous acidf What terms, then, can be applied to the sul-
phurous add and the potassium permanganate respectively f

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PREPARATION OF NITROGEN. 68

ZCSPBRIMENT 30.
Preparation of Nitrogen.

Apparatus. Pneumatic trough; phosphorus stand (Fig. 12)
consisting of {a) cork to fit hple in shelf of trough, {b) #16
copper wire, and (c) blaclcboard crayon ; iron forceps, stirring
rod, burner, wide-mouth bottle (8 oz.), glass plate.

Material. Small piece of phosphorus kept under water, filter
paper, wooden splinter.

Hollow a cavity in the end of a piece of blackboard
crayon. Place it in the wire stand (J, Fig. 12) and insert
cork in the hole in the shelf of a pneumatic
trough. Fill the trough to 1 cm. above the
shelf. Have close at hand an 8 oz. wide-
mouth bottle.

Take, with a pair of forceps, a piece of
phosphorus about half the size of a pea,
remove the adhering water with a bit of
filter paper, and place the phosphorus in the
hollow of the crayon.

Touch the phosphorus with a warm stirring
rod and immediately invert over it the wide-
mouth bottle, which should rest on the shelf
of the trough. Carefully note and record the ^. J2
results.

xxry 1 1 • -IT- 1 T 1 1 fl, cork: b, J16

When the white cloud m the bottle has copper wire;
cleared, press the phosphorus stand from below ^' ^~y°°-
up into the bottle. Slide the bottle to the edge of the
shelf and allow the phosphorus stand to drop down into
the trough.

Cover the mouth of the bottle with a glass plate,
invert and stand on the desk. Note and record the

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54 LABORATORY EXERCISES.

appearance of the nitrogen. Introduce a lighted splinter.
Result ?

What constituent of the air was removed hy the phosphorus?
What other constituents still remain with the nitrogen?

Altemative Method.

Apparatus. Pneumatic trough, two wide-mouth bottles, glass
plate, ring-stand with one ring and one clamp, 250 c.c. Er-
lenmeyer flask with two-hole rubber stopper to fit, thistle-
tube, delivery tube, wire gauze with asbestos center, Bunsen
burner, test-tube.

Material. Sodium nitrite, NaNOg. ammonium chloride,
wooden splinter.

Put 16 grams of sodium nitrite and 10 grams of
ammonium chloride into a 260 c.c. Erlenmeyer flask.

Fit the flask with a two-hole rubber stopper carrying a
thistle-tube and a delivery tube leading to a pneumatic
trough. Support the flask on a wire gauze resting on the
large ring of a ring-stand.

Add a test-tubeful of water to the flask through the
thistle-tube.

Gently heat the flask so that the nitrogen will be
evolved at a temperature considerably below the boiling
point of water. In case frothing occurs from overheat-
ing, pour a few cubic centimeters of cold water into the
thistle-tube.

After the air has been displaced from the flask, collect
the nitrogen in wide-mouth bottles.

Lower a lighted splinter into a bottle of nitrogen.
Result?

Has the nitrogen of the air an odor? Smell a bottle of

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« PREPARATION OF AMMONIA. 55

the nitrogen collected. What does this remit show about
the nitrogen collected?

The nitrogen in the present experiment results from
the decomposition of ammonium nitrite. This compound
is so unstable that it is usually freshly prepared by the
interaction of ammonium chloride and sodium nitrite.
Complete the equations :

NH^Cl + NaNOg — ^ NH^NOg +

NH^NOg— ^N2+... HjO.

EXPERIMENT 31.
Preparation of Ammonia.

Apparatus. Ring-stand, clamp, test-tube rack, three test-
tubes, stopper (one-hole) and delivery tube, perforated card-
board square, Bunsen burner, wide-mouth bottle.

Material. Slaked lime, ammonium chloride, ammonium sul-
phate, sodium hydroxide solution, red and blue litmus.

(a) Take a little ammonium chloride in one hand and
in the other a little slaked lime (dry). Smell of each.
Rub the two together between the palms of the. hands.
Smell the mixture cautiously. Bring a moist strip of
litmus near the mixture. Results ?

(i) Repeat, using ammonium sulphate and slaked lime.
As before, smell, and apply litmus test. Results ?

(c?) To a little sodium hydroxide solution in a test-tube
add a small amount of ammonium chloride. Heat gently,
smell cautiously, and test with litmus as before. Results ?

Ammonium chloride^ NH^Cl, and amm^onium sulphate^
(N 114)2804, are salts. Regarding the reaction between

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LABOBATORY EXERCISES.

sodium hydroxide and ammonium chloride as a double re-
placement^ name the two products formed,

NaOH + NH^Cl— ^ +

Ammonia gas^ NHg, results from the decomposition of on^
of the products. Write the equation for this decomposition.
Complete the equation for the action in (a).

Ca(OH)2 + 2NH^Cl— ^CaCl2 +

— ^CaCl2 + ... + ...

Write the equation for the action in (6).

How could you prove that a substance
given you was an ammonium salt?

(d) Mix, on a piece of paper, a quar-
ter of a test-tubeful of ammonium
chloride with a quarter of a test-tube-
ful of slaked lime. Put the mixture
into a test-tube provided with a de-
livery tube for the collection of the
gas by upward displacement (see Fig.
13) . Warm the mixture very gently.
Fill a dry test-tube and a dry bottle
with the gas and use as directed in
Experiment 32, Save the generator
Fig. 13. for use in Experiment 32 (d).

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PROPERTIES OF AMMONIA. 67

EXPERIMENT 32.
Properties of Ammonia.

Apparatus. Ring-stand, clamp, perforated cardboard square,
test-tube rack, four test-tubes, two wide-mouth bottles (about
6 oz.), two glass plates (about 3 x 3"), battery jar or dish of
water, generator from Experiment 31 (d).

Material. Ammonia gas prepared in Experiment 3 1 , red and
blue litmus paper, sodium hydroxide solution, concentrated
hydrochloric acid.

(a) Note the color of the ammonia gas. Is this gas
lighter or heavier than air ?

(J) Place a test-tube of ammonia m6uth downward ini
a dish of water. Result ? What does this show ?

(c) Pour into a warm, dry bottle two drops of concen-
trated hydrochloric acid. Cover this bottle with a glass
plate and invert it upon a covered bottle of ammonia.
Keeping the bottles mouth to mouth, remove both plates
at the same time. Note where action begins and how it
progresses.

Allow the product to settle. When the product has
settled, allow the bottles to stand open for a few minutes,
so that the unused ammonia may escape. Add a little
sodium hydroxide solution to the deposit and warm gently.
What odor do you detect ?

The deposit was an ammonium salt. Write the equation
accounting for its formation.

(ji^ Caotion 1 FoUow directions as to the position of the end of the
deUvery tube.

Swing around the delivery tube of the generator, so that
its free end is just above the surface of the water in a half-
filled test-tube.

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58 LABORATORY EXERCISES.

After several minutes, remove the test-tube and see
what action the liquid has on litmus. Keep the liquid for
use in (e).

What kind of a substance must be in the water? Write
the equation to show its formation.

(e) Pour a little of the solution from (d) into another
test-tube. Heat to boiling and smell cautiously. Con-
tinue the boiling for some time. Smell and test with
litmus.

Explain what must have happened to the compound dis-
solved in the water. What does this show about its stability f
Write the equation.

EXPERIMENT 33.
Preparation and Properties of Nitric Acid.

Apparatus. Retort, small flask, two test-tubes, battery jar,
ring-stand with large ring, wire gauze with asbestos center,
clamp, Bunsen burner, funnel or thistle-tube.

Material. Sodium or potassium nitrate, concentrated sul-
phuric acid, ferrous sulphate, copper strip, splinter.

CaotionI Concentrated salphoiic and nitric acids are dangerous to both
flesh and clothing.

(a) Put about 30 grams of sodium (or potassium)
nitrate into a tubulated retort. Place the retort on a
wire gauze. Insert the neck of the retort as far as possi-
ble, but not tightly, into a flask partly immersed in water.

Clamp the retort in position and pour 20 c.c. of con-
centrated sulphuric acid through a funnel or thistle-tube
upon the nitrate.

Replace the stopper and heat gently. What do you
notice on the sides of the bulb above the mixture?

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PROPERTIES OF NITRIC ACID. 69

Nitric add both at 120® (7. What two changes of state
take place in the distillation of the acid?

Distil, at as low a temperature as possible, as long as any
nitric acid runs down the neck of the retort. There is a
decided difference in the appearance of the retort after
all the nitric acid has passed over.

Allow the retort and its contents to cool in position.

Why do we use sulphuric acid in the preparation of nitric

acid? Why not use hydrochloric acid? Complete the

equation: ^t ii.t^ tt o^
^ NaNOg + HgSO^ — ^ +

(6) N.B. The acid collected is much more active than
the ordinary nitric acid. Use very carefully and throw
all solid materials in the waste jars immediately after
examining them.

In separate test-tubes, try the action of a few drops of

the acid on: ,^. . . .

(1) a piece of wood;

(2) a small piece of copper.

(<?) Test for a Nitrate. The test must be performed
exactly as described to secure any decisive results.

Pour into a test-tube a concentrated solution of ferrous
sulphate.

Carefully pour down the side of the tube 5 c.c. of sul-
phuric acid. The sulphuric acid should form a distinct layer
below the ferrous sulphate. Do not shake the test-tube.

In the same way, pour down the side of the tube a few
drops of very dilute nitric acid.

Note and describe the characteristic coloration between
the two layers.

Repeat the test, using a solution of a nitrate instead of
nitric acid.

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60 LABORATORY EXERCISES.

BXPERIBfEN'T 34.
Preparation of Nitric (hdde.

Apparatus. Four wide-mouth bottles (6 or 8 oz.), two-hole
rubber stopper to fit wide-mouth bottle, thistle-tube, delivery
tube, pneumatic trough or dish, test-tube.

Material. Copper (wire, rivets, or turnings), concentrated
nitric acid.

Arrange a wide-mouth bottle with a stopper canying a
thistle-tube. Place in the bottle about 10 grams of copper
and cover with a test-tubeful of water.

Pour about 10 c.c. (one third test-tube) of concentrated
nitric acid through the thistle-tube of the generator and
wait for the action to start. Collect the gas by the dis-
placement of water.

Note the color of the gas which first appears in the gen-
erator. Observe at this time the behavior of the water in
the delivery tube.

The colorless gas is nitric oxide. Collect two bottles
full of it and one bottle half full. Keep for Experi-
ment 35.

The action in the generator may be maintained by add-
ing from time to time small quantities of the concentrated
nitric acid.

Note the color of the liquid in the generator. This
color is characteristic of the water solutions of copper salts.

What gas is usually produced hy the action of an add
with a metal? Why do we not get this gas here f What he-
comes of it? How^ then^ do you account for the formation of
nitric oxide ? Complete the equation :

3 Cu -h 8 HNOg— ^ 3 Cu(N08)3 + ... + ...

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PROPERTIES OF NITRIC OXIDE.

EXPERIMENT 35.
Properties of Nitric (hdde.

Apparatus. Test-tube with two-hole rubber stopper, delivery
tube, 2 c.c. pipette with rubber bulb (" medicine dropper").

Material. Nitric oxide collected in preceding experiment,
sodium peroxide.

(a) Allow a little nitric oxide to escape into the air.
What evidence of chemical change do you observe ?

(6) Fit a small dry test- (^
tube with a rubber stopper
carrying a delivery tube and
a medicine dropper.

Place 1 gram of sodium
peroxide in the dry test-
tube. Fill the pipette with
water and insert the rubber
stopper into the test-tube.

Q-ently press the rubber
bulb of the dropper so that
one drop of water falls on
the sodium peroxide. The
decomposition which results
produces oxygen gas :

2Na202-h2H20.

\=#^

V-y

Fig. 14.
.4NaOH4-02.

Allow the air in the test-tube to be displaced by the

oxygen. If the action stops, let another drop of water

fall on the peroxide.

Caation 1 To ayoid yiolent action, use the water in small amounts with
interrals between.

Allow some of the oxygen to pass up through water into
a bottle half filled with nitric oxide. Results? Compare

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LABORATORY EXERCISES.

the result with that obtained by allowing air to mix with
the nitric oxide. With what gaB in the air does the nitric
oxide combine ?

Complete the equation:

2NO+O2— ^

How do you account for the reddish hrown ga% that
appeared in the generator at the beginning of Experiment 34 ?
How do these two oxides of nitrogen compare in solubility?

EXPERIMENT 36.

Preparation and Properties of Nitrous (hdde.

Apparatus. Flask and small bottle, with stoppers and delivery
tubes as shown (Fig. 15), ring-stand, clamp, Bunsen burner,
four bottles (6 oz.), dish of water, deflagration spoon, asbes-
tos paper, glass plate.

Material. Ammonium nitrate, anhydrous copper sulphate,
splinter, roll sulphur.

(a) Put 10 grams of pure, crystallized ammonium
nitrate into the flask and arrange the apparatus as shown
^_^ in the figure. Heat the

^ ^ ' flask very cautiously, keep-

ing the flame in constant
motion. If brown fumes
appear in the flask during
the heating, allow the flask
to cool a little.

Collect three and a half
bottles of nitrous oxide by
the displacement of water.
Drop' a little anhydrous
copper sulphate into the small bottle. What is the liquid
in the bottle ?

CJ4.

Fig. 15.

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PROPERTIES OF NITROUS OXIDE. 63

Complete the equation :

NH^NOg— ^N20 + ...

(J) Has the gas an odor?

Place the palm of the hand over the mouth of the half-
filled bottle. Press down tightly and shake vigorously.
Result? Explain.

(e?) Lower a splinter having a spark on one end into a
bottle of nitrous oxide. Result ?

Place a piece of roll sulphur, about the size of a pea, in
a deflagration spoon lined with asbestos paper and barely
ignite the sulphur by directing the flame of the burner
on to it from above. Use care not to warm the spoon
more than is absolutely necessary. Lower the spoon con-
taining the feebly burning sulphur into a bottle of nitrous
oxide. Result ? Remove the spoon, and cover the mouth
of the bottle. Heat the spoon until the sulphur burns
vigorously, then lower it into the nitrous oxide. Result ?

Is the same compound of sulphur formed when sulphur
bums in nitrous oxide that is formed when sulphur bums
in air? Give a reason for your answer.

How would feebly burning sulphur behave if placed in
oxygen ?

Sow could you determine whether a gas was nitrous oxide
or oxygen?

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64 LABOEATORY EXERCISES.

EXPERIMENT 37.
Preparation of Potassium Nitrate.

Apparatus. Tripod, wire gauze with asbestos center, two
beakers, test-tube (capacity 30 c.c.) for measuring hot water,
platinum or iron wire, Bunsen burner, watch glass, magnify-
ing glass.

Material. Potassium chloride, sodium nitrate.

Make a hot concentrated solution of 25 grams of sodium
nitrate by dissolving it in 20 c.c. of hot water in a beaker.

Put 22 grams of potassium chloride in approximately
30 c.c. of hot water.

Then pour the sodium nitrate solution into the beaker con-
taining the potassium chloride. Boil for several minutes.

In order to determine what has separated from the
mixture, stop the heating and allow contents of beaker to
settle. Immediately pour the mother liquor into a clean
beaker and allow to crystallize. With a very few cubic
centimeters of hot water wash the white substance remain-
ing in the bottom of the first beaker. Determine what it
is by tasting it and by applying the flame test. Dissolve
a little of it in cold water and allow the solution to evapo-
rate on a watch glass. Examine the crystals under a
magnifying glass.

Take the beaker in which the mother liquor was set
aside to crystallize and pour off the liquid. Dissolve the
crystals in the smallest possible amount of hot water and
recrystallize. The potassium nitrate is purified by this
process of recrystallization. Examine the crystals of
potassium nitrate and describe or make a drawing of them.

Compare the solubility of potassium nitrate in hot water
with its solubility in cold water. Write the equation for the

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PREPARATION AND PROPERTIES OF BROMINE. 65

reaction between the sodium nitrate and potassium chloride
solutions. Explain how the solubility of the two products
makes the method of this Experiment a good one for the prepa*
ration of potassium nitrate.

EXPERIMENT 38.
Preparation and Properties of Bromine.

Apparatus. Ring-stand, clannp, four test-tubes, one-hole
stopper and a delivery tube, Bunsen burner, test-tube rack.

Material. Potassium bronnlde, manganese dioxide, sulphuric

acid (2 to 1), carbon disulphide or chloroform, chlorine water.

Cantioii I Keep flames away from carbon disulphide. Its vapor is ezplosiye
when mixed with air.

(a) On a piece of paper, mix 1 gram of potassium
bromide with one fourth of its bulk of manganese dioxide.

Fit a test-tube with a one-hole stopper carrying a
delivery tube. Pour about 8 c.c. of sulphuric acid
(2 to 1) into the test-tube and add the mixture of potas-
sium bromide and manganese dioxide. Clamp the tube
containing the mixture so that the delivery tube shall ex-
tend to the bottom of an empty test-tube standing in a
beaker of water. Warm the test-tube containing the
mixture very gently.

Note the color of the bromine vapor and of the liquid
bromine.

Nearly fill the test-tube containing the bromine with
water. Save the mixture for future use.

Is the specific gravity of bromine more^ or less^ than one f
Is bromine soluble in water f

(6) Add a few drops of carbon disulphide to a test-tube
one third full of water, and shake.

Are the two liquids miscible ; that is, are they completely
soluble in each other ?

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66 LABOBATOBY EXEBCI8E8.

(<?) Add a few drops of the bromine water obtained in
(a) to the mixture of carbon disulphide and water. Shake
the resulting mixture vigorously and then allow it to
stand for a short time.

Is bromine more soluble in water than it is in carbon
disulphide ? Note the color imparted to the carbon di-
sulphide by the free bromine.

(d) Dissolve a small crystal of potassium bromide in
2 or 3 c.c. of water, add a little carbon disulphide, and
shake. Is the carbon disulphide colored? Save the re-
sulting mixture for (e).

In what condition must bromine he^ in order to color carbon
disulphide ?

(/) To the mixture obtained in (d) add a few drops
of chlorine water, and shake.

Is the resulting color characteristic of a carbon disul-
phide solution of bromine ? Try to account for the changes
that have taken place :

What compounds would we expect to have formed hy the
action of potassium bromide with sulphuric add?

How is the action modified by the presence of manganese
dioxide f (^Think of the preparation of chlorine by the ad-
dition of sulphuric acid to a mixture of sodium chloride and
manganese dioxide.)

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P,BEPARATION AND PROPERTIES OF IODINE. 67

EXPERIMENT 39.
Preparation and Properties of Iodine.

Apparatus. Seven test-tubes, test-tube rack, Bunsen burner >
splinter, paper (15x5 cm.).

Material. Potassium iodide, manganese dioxide, sulphuric
acid (2 to 1), alcohol, potassium iodide solution, chloroform
or carbon disulphide, chlorine water, bromine water.

(a) Mix 1 gram of potassium iodide with one fourth
its bulk of mauganese dioxide on a piece of paper.

Roll the paper into a cylinder and insert it with its con-
tents into a dry test-tube held horizontally. Raise to a
vertical position, so that the mixture will fall to the
bottom of the tube without touching the sides. With-
draw the paper and add 2 c.c. of sulphuric acid (2 to 1).

Warm very gently. Results ?

(J) With a splinter remove small portions of the
deposit on the sides of the tube, and try to dissolve them in
(1) water, (2) alcohol, (3) water and potassium iodide,
(4) chloroform (or carbon disulphide).

Record results in tabular form:

Solvent.

Degbbk of Solubility.
(Slightly, moderately, or very.)

(e?) To about 3 c.c. of a very dilute solution of potas-
sium iodide add a few drops of chlorine water. Result ?

Add carbon disulphide to the mixture and shake.
Result?

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68 LABOBATOBT EXEBCI8Ea.

Account for the coloration of the carbon duulphide. Write
an equation for the action between the potassium iodide and
the chlorine.

(d) To another portion of the potassium iodide solu-
tion add bromine water and carbon disulphide. Shake.
Results ? Explain and write equation as before.

Which of these halogens is most easily replaced in its com-
pounds? Which is lea^t easily replaced? Arrange the
halogen elements in the order of their relative replacement.

EXPERIMENT 40.

The Halogen Acids.

Apparatus. Three test-tubes, test-tube rack, Bunsen burner.
Material. Sodium chloride, potassium bromide, potassium
iodide, concentrated sulphuric acid, litmus paper.

(a) To 1 gram sodium chloride in a test-tube add a few-
drops of concentrated sulphuric acid. Warm gently.
Result ?

Bring a strip of moist litmus to the mouth of the test-
tube. Result?

Blow across the mouth of the test-tube and notice the
fuming of the gas with the moisture of the breath. The
amount of the fuming roughly indicates the quantity of
the acid issuing from the tube.

If hydrochloric acid were unstable, into what two ele-
ments would it decompose ? What would be the color of
such a mixture of gases? Do you find this color in the
test-tube in which you generated the hydrochloric acid?
What is your decision as to the stability of this acid? Write
the equation for its preparation.

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THE HALOGEN ACIDS. 69

(6) To 1 gram of potassium bromide in a test-tube add
1 c.c, of concentrated sulphuric acid. Warm gently, if
necessary. Result?

Test the gas with moist litmus. Result? Write the
equation for the preparation of the acid.

What is the color of the gas in the test-tube ? What
gives this color and what does it indicate as to the stability
of the hydrohromic acid f

Smell the test-tube very cautiously. Can you detect
the odor of sulphur dioxide ?

Sulphur dioxide is the anhydride of what acid ? What
name is given to the process by which sulphuric acid is
converted into sulphurous acid? What element in the
hydrobromic acid might bring about this change ? Now
account for the production of sulphur dioxide when concen-
trated sulphuric acid reacts with potassium bromide.
(^Recall the action of copper with hot^ concentrated sulphuric
acid.^ In the present experiment where did the free bromine
come from?

(e?) To 1 gram of potassium iodide in a test-tube add
1 c.c. of concentrated sulphuric acid.

Test the gas with litmus and determine amount of fum-
ing, as before. Results? What do these results show
about the amount of hydriodic acid issuing from the tube ?
Compare the stability of this acid with that of hydrobromic
acid.

Smell the test-tube cautiously. Result? What pro-
cess would form hydrogen sulphide from sulphuric add f
Show how this is accomplished by the hydriodic acid,
accounting for the production of the iodine at the same
time. ( Compare with action of sulphuric acid on potassium
bromide.^

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LABOBATORY EXBBCISE8.

Which of these three halogen adds is most stable f Which
has the greatest heat of formation? Which is the most
easily oxidized by sulphuric acid ? (^Give a reason for your
last answer.)

HEATS OF FORMATION OF THE HALOGEN ACIDS.

Hydrobromic acid ... + 8,400 calories
Hydrochloric acid ... + 22,000 calories
Hydriodic acid •.. — 7,000 calories

BXPERIBftBNT 41.

Destructive Distillation.

Apparatus. Hard* glass test-tube, two sets of stoppers and
delivery tubes as shown (Fig. 16), two small bottles, ring-
stand, clamp, Bunsen burner.

Material. Wood (splinters), soft coal, litmus paper.

(a) Arrange apparatus as shown (Fig. 16). Fill a hard
glass test-tube with splinters of wood. Heat gently at first
and then strongly until no further
change can be noted. While heating,
bring a flame to the end of the jet
tube. Result ?

When the action is complete, allow
the apparatus to cool and then
examine the contents of the test-tube.
What is the substance found there ?
How does it differ from the original
wood?
liquid in the bottle with litmus paper.

Fig. 16.

Test the
Result ?

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PROPERTIES OF CARBON. 71

The decomposition of material into simpler substances
by means of heat is called destructive distillation.
Name three products of the destructive distillation of wood.

(6) Place a few pieces of finely crushed soft coal in the
hard glass tube. Replace the bottle and tubes with a fresh
set. Heat as before. Results ?

Test the gas at the end of the jet tube with a flame.
Result ?

When the heating is complete, examine and identify the
substance left in the test tube.

Test the contents of the bottle with litmus paper. Re-
sult?

Name three products of the destructive distillation of soft
coal.

EXPERIMENT 42.
Properties of Carbon.

Apparatus. Hard glass test-tube with stopper and delivery

tube, two test-tubes, two 250 c.c. beakers, funnel, ring-stand

and clamp, Bunsen burner.
Materiau Copper oxide, powdered charcoal, lime-water,

boneblack, cider vinegar, copper sulphate solution, ferrous

sulphide, dilute sulphuric acid, filter paper.

(a) Mix 5 grams of copper oxide with 1 gram of pow-
dered charcoal. Pour the mixture into a hard glass test-
tube, and arrange the apparatus so that the gas evolved
when the tube is heated will bubble through a little lime-
water in a test-tube.

Heat the hard glass tube, commencing at the part around
the upper part of the mixture, and gradually moving the
flame toward the closed end of the tube.

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72 LABORATORY EXERCISES.

What change first takes place in the lime-water? The
gas producing this change is carbon dioxide.

Allow the tube to cool and when cold pour its contents
into a 200 c.c. beaker. Let a small stream of water flow
into the beaker. What substance is carried away by the
water? What is left in the beaker?

What element is taken from the copper oxide? What
name is given to such a change ?

(6) Thoroughly mix a little boneblack with some cider
vinegar in a small beaker. Fold a piece of filter paper
and place it in a funnel. Pour some boneblack on to the
filter paper and scoop out a hollow in the center of the
boneblack. Into this hollow pour the mixture of vinegar
and boneblack. Collect the filtrate and note its color.

Filter a solution of copper sulphate through boneblack.

Can the color be removed from all liquids by filtering
them through boneblack ?

Why is crude sugar dissolved in water and filtered
through boneblack?

(c) Place a small piece of ferrous sulphide in a test-tube
and add 10 c.c. of water and 5 c.c. of dilute sulphuric acid.
Result? Note odor. When the action becomes vigorous,
half fill the tube with boneblack. Shake and observe
odor.

What use of carbon depends on this property? (Ola^s
discussion.^

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PROPERTIES OF CARBON DIOXIDE, 73

EXPERIMENT 43.
Preparation and Properties of Carbon Dioxide.

Apparatus. Eight-ounce bottle, stopper carrying doubly bent
delivery tube and thistle-tube, three wide-mouth bottles, three
test-tubes, glass tube, pneumatic trough.

Material. Marble chips, concentrated hydrochloric acid,
candle, lime-wiater, splinter, solution of blue litmus.

(a) Put 15 grams of marble chips (calcium carbonate)
into a bottle provided with a doubly bent delivery tube,
and a thistle-tube reaching nearly to the bottom of the
bottle. Cover the marble with water, and add concentrated
hydrochloric acid, a few cubic centimeters at a time, so as
to get moderate action. Collect three bottles of the gas
by the displacement of water.

(J) Take two. test-tubes a third full of blue litmus solu-
tion. Set one tube aside. Let the gas from the generator
bubble through the other. Result ? (If the result is not
evident, compare this litmus solution with the one set
aside.) What does the result show in regard to the solu-
bility of carbon dioxide ? Is carbon dioxide an anhydride f
Why?

((?) Has carbon dioxide color ? Odor ?

(d) Invert a bottle of carbon dioxide over a lighted
candle. Result ? What two properties of carbon dioxide
are shown in this action ?

(e) Pour a few cubic centimeters of lime-water into a
bottle of carbon dioxide and shake. Result ?

(/) Burn a wooden splinter in a bottle of air. Add
lime-water and shake. Result ? What does this show?

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74 LABORATORY EXERCISES.

(^) Blow through a glass tube into a test-tube half full
of lime-water. Result? Explain.
(K) Complete the equation:

CaCOg+HCl— ^CaCl3 +

— ^CaCl2 + ... + ...

Why can any of the common acids he used in preparing
carbon dioxide f

EXPERIMENT 44.
Hard Waters.

Apparatus.* Carbon dioxide generator (Experiment 43) with
delivery tube for leading gas into test-tube, six test-tubes,
rubber stopper (to fit test-tube) with delivery tube, funnel,
Bunsen burner.

Material. Calcium sulphate (gypsum or plaster of paris),
magnesium sulphate, lime-water, distilled water, filtered
soap solution, filter paper.

(a) Put a pinch of plaster of Paris (calcium sulphate)
into a test-tube full of cold water. Shake thoroughly and
then filter. The filtrate is permanent hard water. Rub
some of it between the palms of the hands. To another
portion add a few drops of soap solution. Shake. Have
suds formed? Has a precipitate formed?

(6) Pass carbon dioxide into a test-tube nearly full
of lime-water (water solution of calcium hydroxide,
Ca(0H)2). What is the first effect? Write the equation^
remembering that the visible product of the reaction is
calcium carbonate.

What happens to the calcium carbonate on the con-
tinued passing of the carbon dioxide? What compound
is formed when carbon dioxide combines with ordinary

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HARD WATERS. 76

water? This compound acts on the calcium carbonate
to form the soluble compound, calcium bicarbonate,
CaH2(COg)2. Write the equation.

The water solution of calcium bicarbonate is known as
"temporary" hard water. Keep it for use in (<?).

((?) If the temporary hard water obtained in (6) is not
perfectly clear, filter it. Divide it into three portions,
setting one test-tube aside for use in (tf).

Close the mouth of the test-tube containing one portion
of the hard water with a rubber stopper carrying a
delivery tube. The free end of the delivery tube should
be 1 cm. above a little lime-water in another test-tube.
Heat the temporary hard water to boiling. Result?
Write the equation which accounts for this softening of the
hard water.

To another portion of the temporary hard water add
lime-water. Result ? Write the equation.

What are two ways of softening temporary hard water f

(t?) Add a few cubic centimeters of a clear soap solu-
tion to a little distilled water. Shake. How readily does
the distilled water form suds with the soap ?

To a portion of the temporary hard water, obtained in
(6), add two drops of the soap solution. Shake. Do
suds form? Has anything formed in the test-tube?

Continue adding the soap solution, a few drops at a
time, and shake after each addition. Note when the
water forms suds freely. The flocculent precipitate float-
ing in the liquid is an insoluble calcium soap. Can you
tell from what it has been formed ?

Why is not hard water suitable for washing purposes t
Explain.

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LABOBATOBT EXERCISES.

(e) Dissolve a little magnesium sulphate in water.
Does it make the water hard ? Is the hardness temporary
or permanent ? Give your reason.

EXPERIMENT 45.
Preparation and Properties of Carbon Monoxide.

Apparatus. 250 c.c. flask, two-hole rubber stoppers, wide-
mouth bottles, rubber connections, thistle, delivery, and con-
necting tubes as shown (Fig. 17), pneumatic trough, glass
plate, ring-stand with two rings, wire gauze (asbestos center),
burner.

Material, Crystallized oxalic acid (Poison), concentrated

sulphuric acid, caustic potash solution (1:2), lime-water.

Caution I Remember that hot, concentrated sulphuric acid produces fright-
f ul burns, and that carbon monoxide is a poisonous gas.

Arrange apparatus as in diagram (Fig. 17). Note that
the entrance tube into each wide-mouth bottle extends
nearly to the bottom of the bottle.

Pour lime-water into the first and
fourth wide-mouth bottles until they
are one sixth full. Similarly add a
concentrated solution of caustic potash
to the second and third bottles. Re-
move the stopper from the generating

Fig. 17.
flask and put in 15 grams of crystallized oxalic acid. Re-
place the stopper and pour through the thistle-tube 60 c.c.
of concentrated sulphuric acid.

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PROPERTIES OF CARBON MONOXIDE. 7T

Make sure that the joints and connections of your appa-
ratus are tight. Then ask the instructor to inspect your appa-
ratus. Inquire whether it is safe to proceed with the heating.

Heat with a small Bunsen flame, but remove the flame
as soon as the action is well started. If the action
becomes too slow, replace the burner under the flask for a
short time. 77ie success of the experiment depends on
having a moderate rate of bubbling in the first bottle.

Describe the action in the generating flask. What
happens in the first bottle ? What produces this effect?

Does any of this gas reach the fourth bottle? What
becomes of it? (Compare the rate of bubbling in the
first bottle with that in the fourth.)

Discard the first two bottlefuls of gas collected. Why?

Fill the bottle a third time, cover the mouth with a
glass plate, invert, and set it upon the table. Light the
bottle of gas. (If the gas does not burn quietly, collect
another bottle.) Result? Pour a little lime-water into
the bottle, cover the mouth of the bottle with the hand,
and shake. Result ? Write the equation for the burning
of carbon monoodde.

Disconnect at once the generating flask from the first bottle.

The oxalic acid, H^C^^^ is decomposed by the sulphuric
acid in the generator. Name two gaseous products which
pass out of the generator. By completing the following
equation, find out the third product of the reaction.

HaC^O^-^CO-f- +

For what purpose was sulphuric add used in the generator f
Why were the lime-water and potash solution u^sed ?

Why might the flames of burning hydrogen and carbon
monoxide be confused? How can you distinguish them
by the products of combustion?

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78 LABORATORY EXERCISES.

EXPERIMENT 46.

Borax and Boric Acid.

Apparatus. Funnel, beaker (100 c.c), evaporating dish.
Material. Borax, concentrated sulphuric acid, alcohol,

dilute hydrochloric acid, ammonium hydroxide solution,

filter paper, turmeric paper.

Make a solution of borax by dissolving 12 grams of
borax in 50 c.c. of boiling water. Drop by drop, add
6 c.c. of concentrated sulphuric acid to the solution and
allow it to cool. Boric acid will separate as shining, scale-
like crystals. Collect the crystals on a piece of filter
paper in a funnel and wash them with a little cold water.

Complete the equation : —

NagB^O^ + HaSO^ + 5 Ufi -> 4 HgBOg +

Place some of the boric acid you have prepared in an
evaporating dish and just cover it with alcohol. Set fire
to the alcohol. Note the color of the flame.

Treat a little borax in the same manner that you have
just treated the boric acid. How does this flame differ
in color from the preceding flame ?

Dip a piece of turmeric paper in a solution of boric acid
and then dry the paper at a temperature a little above
100** C. Note the reddish coloration of the paper. Add
to the paper a little ammonium hydroxide and observe
the change in color. Determine whether dilute hydro-
chloric acid will restore the color of turmeric paper after
it has been changed by boric acid.

Acidulate a solution of borax with hydrochloric acid
and make the turmeric paper test for boric acid.

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DOUBLE DECOMPOSITION BT PRECIPITATION. 79

EXPERIMENT 47.

Double Decomposition by Precipitation.

Apparatus. Nine test-tubes, test-tube rack.

Material. Barium nitrate, barium sulpliate, calcium carbon-
ate, sodium carbonate, dilute nitric acid, dilute sulphuric
acid, solutions of barium chloride, potassium carbonate, cal-
cium and sodium nitrates ; other solutions as required in (e).

(a) Test the solubility of barium nitrate by adding 10
c.c. of water to a pinch of the solid salt. Do the same with
barium sulphate. Warm if necessary. Results?

(J) To 5 c.c. of a solution of barium chloride add a little
dilute nitric acid. What barium salt might be formed by
a recombination of the ions ? Is there any evidence that
such a compound is formed ?

To another portion of barium chloride solution add a
little dilute sulphuric acid. What barium salt might be
formed in this case by a recombination of the ions ? Is
there any evidence that it actually is formed ? Equation ?

Tabulate your results as indicated below. What relation
18 there between the separation of a compound as a precipitate^
as shown in (J), and its solubility as shovm in (a) ?

This illustrates a very important general principle.
Test it in another case as follows:

(<?) Test the solubilities of calcium carbonate and sodium
carbonate as in (a). Results ?

(d) To a solution of sodium nitrate add a solution of
potassium carbonate. Is there any evidence that a new
sodium compound is formed? Connect this result with
the test for the solubility of sodium carbonate in (c).
Tabulate results.

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LABORATOUr EXERCISES.

To a solution of calcium nitrate add a solution of potas-
sium carbonate. Is there any evidence that a new calcium
compound is formed ? Equation ? Connect this result
with the test for the solubility of calcium carbonate in
(<?). Tabulate results.

Give the formal statement of the general principle which
the results illustrate.

TABULAR FORM.

SUBSTANOB.

Solubility in Watke.

Did thk Substance pbe-
cipitatb on mixing solu-
TIONS CONTAINING NbCKS-

SABY Ions?

(je) Which of the following list of compounds can be
obtained as precipitates by double decomposition ? (Con-
sult the Table of Solubilities on page 122.)

silver chloride copper nitrate

ferrous chloride ferric hydroxide

copper sulphide magnesium chloride

Test your conclusion in at least two cases by bringing
together the solutions that contain the proper ions.

How can this principle he used as a means of preparing^ in
a pure condition^ certain insoluble compounds ; certain solvhle
compounds ?

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FOUR WATS OF PREPARING SALTS. 81

EXPERIMENT 48.

Four Ways of Preparing Salts.

Apparatus. Test-tubes, beakers, etc., as required.
Material. Solids and solutions as required.

. The four chief methods of preparing salts are : —

(a) Direct combination of elements.

(J) Neutralization.

((?) Double decomposition due to insolubility (precipi-
tation).

(d) Double decomposition due to volatility.

Devise plans for preparing a salt in four ways (if pos-
sible) in accordance with the above principles. Submit
your schemes to the instructor for approval previous to
the laboratory period. In case you find but three ways
applicable to the salt you select, prepare another salt
according to the fourth way.

The following list of salts is suggested:

NaCl NaaSO^ Cu(N08)a CuS Hgl,

FeS Pblj
ZnS

KCl

KjSO^

KNOg

CaCla

CuSO^

NaNOg

FeCl,

ZnSO^
MgSO,

(This experiment may be varied by having all the students make
the same salt, and then proceed to the salts assigned individually by
the instructor.)

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LABORATORY EXERCISES.

EXPERIMENT 49.
Cobalt Nitrate Tests.

Apparatus. Plaster block ^ or charcoal stick, blowpipe, forceps.

Bunsen burner.
Material. Zinc sulphate, alum, magnesium sulphate, cobalt

nitrate solution with dropper, unknowns.

(a) Put a little of some zinc compound, as zinc sulphate,
in a cavity made in a plaster block or a piece of charcoal.
Heat it as hot as possible at the end of the blowpipe flame.
Allow residue to cool and moisten it with a drop or two
of cobalt nitrate solution.

Again heat intensely and, on cooling, note the color of the
mass on the charcoal. Record results in a table.

TABLE.

Compound Taken.

Color of Rbsidue after
F1R8T Hbatino.

Color of Residue after Heating
WITH Cobalt Nxtratb.

(J) Take an aluminum compound, as alum, and repeat
test as made with the zinc compound, so as to obtain a
characteristic coloration.

^ Plaster blocks may be made by mixing plaster of Paris and one
third its weight of water, to the consistency of batter. Pour the mixture
on a glass plate and, when it is partially set, mark off rectangles 4" by 1"
with a knife. When hard, the blocks may be easily broken apart.

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BORAX BEAD TESTS. 83

EXPERIMENT 50.

Borax Bead Tests.

Apparatus. Mounted platinum wire, Bunsen burner, blow

pipe, if desired.
Material. Powdered borax, cobalt nitrate or oxide, manga-
nese dioxide, chrome alum or chromium sulphate, ferric
chloride or other Iron compound.
(a) Bend the end of a platinum wire into the shape of a
letter J, 2 mm. across the opening. Heat the loop red-hot
and dip it into powdered borax. Heat again in the hottest
part of the flame. The borax swells, loses its water of
crystallization, and then melts to a transparent glass.

(J) Touch the hot bead to a tiny bit of some cobalt
compound, as cobalt nitrate or cobalt oxide. Heat in
the hot outer portion of the Bunsen or blowpipe flame
(oxidizing flame), until a clear bead is obtained. Note
the characteristic color, and record in a table arranged
as on page 84.

T6 remove the bead, heat it red-hot and quickly shake
off the molten bead into the sink or waste jar. Make a
fresh bead and examine it. If it is not colorless, repeat
the operation.

((?) Touch the newly made bead while hot to a bit of
manganese dioxide. Fuse as before. Note and record
the characteristic color given by manganese compounds.

(t?) Using a chromium compound, e.ff, chrome alum or
chromium sulphate, obtain in a similar manner a char-
acteristic bead.

(e) Obtain the color characteristic of an iron compound
in the oxidizing flame.

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LABORATORY EXERCISES.

TABLE.

EXPERIMENT 51.
Identification of Simple Salts.

Apparatus. Platinum wire, cobalt glass, charcoal or plaster
block, blowpipe, test-tubes, Bunsen burner.

Material. Borax, solutions of cobalt nitrate, silver nitrate,
barium chloride, ferrous sulphate; dilute nitric and hydro-
chloric acids; concentrated sulphuric acid.

Use a very small portion of the unknown given you in
making each test. Always keep a portion for verifier
tion of your results. Keep a tabulated record of all tests,
even those giving negative results. Finally decide what
you have found in the unknovm substance^ with reasons for
your decision. Then take your note book to the instructor.

(cl) Determine the metallic part of the substance by
means of (1) the flame test for sodium and potassium,
(2) cobalt nitrate test, (3) borax bead test.

(6) Now determine whether the unknown contains a
carbonate.

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IDENTIFICATION OF SIMPLE SALTS. 85

(c) Then put a fresh portion of the unknowrf into a
test-tube and try to dissolve it in water, heating if
necessary. Filter if there is an undissolved residue.

Divide the clear liquid into several portions and make
tests for a chloride, a sulphate, and a nitrate.

EXPERIMENT 52.
Action of Metals on Salt Solutions.

APPARATUS. Eight test-tubes, test-tube rack.

Material. Four strips of zinc (1x4 cm.), four copper strips,
No. 30 copper wire, solutions of lead, silver, copper, mercury,
and zinc nitrates, nitric acid, hydrochloric acid.

(a) Place in separate test-tubes solutions of lead, silver,
mercury, and copper nitrates. In each tube, by means
of a wire, suspend a strip of zinc.

(J) Suspend in a similar manner strips of copper in
solutions of lead, silver, mercury, and zinc nitrates.

(c?) Remove the zinc strip which has been suspended
in the solution of mercury nitrate. Rinse, and rub the strip
with the finger. What metal has been deposited on the
zinc ? Bend the strip sharply and observe the broken
edge.

(c?) Remove the copper strip which was suspended in
the solution of mercury nitrate. Rinse and rub the strip.
What has been deposited on the copper ? What does the
color of the solution remaining in the test-tube indicate ? Write
the equation for the reaction of the copper with the mercury
nitrate solution,

{e) Remove the zinc strip from the silver solution,
scraping off the deposit on it into the test-tube. Carefully

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LABORATORY EXERCISES.

pour off the liquid and fill the test-tube with water.
Shake and allow the deposit to settle. Pour off the water
again. Add a few drops of nitric acid. When the
deposit has been dissolved, fill the test-tube half full of
water and add a few drops of hydrochloric acid.

What compound is the precipitated What was the sub-
stance dissolved hy the nitric acid? Write the equation for
the reaction of zinc with the silver nitrate solution.

(/) . Examine all the other strips and tabulate results.

TABLE.

EXPERIMENT 53.
Equivalent of Silver.

Apparatus. Beaker, hompan balance, set of weights, wash
bottle (Fig. 18), glass rod with rubber tubing on the end.

Material. Silver nitrate solution (34 grams per liter), piece
of copper 3x6 cm., thread, filter paper.

Record weighings in a tabular form (cf. page 88).

(a) Weigh accurately on a hompan balance a piece of
clean bright copper. Tie a piece of thread about it, curve
it slightly, and stand it on edge in a beaker containing
enough silver nitrate solution to completely cover it. Al-
low the copper to remain in the solution about an hour.

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EQUIVALENT OF SILVER. 87

Silver is deposited as a result of the action that takes
place. Write the equation.

(J) When the action is apparently complete, loosen the
lightly adhering silver from the copper, and lift the strip
from the solution by the thread. Every
particle of the silver must be washed from
the copper into the beaker. It may be
necessary to scrape the copper gently with
the end of a glass rod covered with a bit of
rubber tubing. A wash bottle (Fig. 18),
by which a fine jet of water can be directed
against the copper, will be of great assist-
ance in getting the silver into the beaker.

Wipe the copper strip, dry, and again P^g- ^S.

weigh it. What does the change in weight represent ?

(c?) While the copper is drying, carefully filter the
contents of the beaker on a weighed filter paper. Be sure
that every particle of the silver is transferred to the filter
paper. The wash bottle will be of great help in this op-
eration also.

The silver must now be thoroughly washed with water.
Cover the deposit on the filter paper with water and allow
it to drain completely before adding another portion.
Wash in this way at least three times. Take at least
twenty-four hours to dry the filter unless the heat of an
air bath or a steam radiator is available.

When dry, weigh the filter paper and its contents.
From this subtract the original weight of the filter paper.

You now have the weight of the copper used, and the
weight of the silver deposited. Using the equivalent of
copper, 81.8, as the third known quantity of a proportion,
calculate the equivalent of silver.

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88 LABORATORY EXERCISES.

TABULAR FORM.

Original weight of piece of copper
Final weight of piece of copper

Weight of copper used

Weight of filter paper and contents

Weight of filter paper

Weight of silver deposited ....
Equivalent of silver

EXPERIMENT 54.
Aluminum Hydroxide.

Apparatus. Three test-tubes, cylinder or beaker, two beakers
(100 c.c), test-tube rack, ring-stand, one ring, wire gauze
with asbestos center, Bunsen burner.

Material. White cotton cloth, lime-water, solutions of alumi-
num sulphate (2%), ammonium hydroxide (1 to 10), alum,
hydrochloric acid (I to 25), logwood solution, alizarine, clay.

(a) To 5 c.c. of a very dilute solution of aluminum sul-
phate in a test-tube, add 10 c.c. of lime-water. Result ?
Write the equation.

(6) To 100 c.c. of turbid water (water having clay in
suspension) in a cylinder or beaker, add 5 c.c. of aluminum
sulphate solution and stir thoroughly. Then add 10 c.c.
of lime-water without stirring. Allow the water to stand,
and note the result. This illustrates a method for the san-
itary clarification of water. What substance removes the
suspended matter?

(tf) To a logwood solution add ammonium hydroxide.
Does a precipitate form ?

To a solution of alum in another test-tube add very
dilute ammonium hydroxide to precipitation.

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ALUMINUM HYDROXIDE, 89

Add logwood solution to the. solution containing the
precipitated aluminum hydroxide. Shake and allow to
settle. What is the color of the supernatant liquid?
What becomes of the logwood? Such a combination is
commonly called a lake.

In a similar way make a lake with alizarine.

(d) Soak a piece of white cotton cloth in a very dilute
solution of hydrochloric acid (1 to 25). Remove the cloth
from the bath, wash it in several changes of pure water,
and then in water containing one or two drops of ammonium
hydroxide. The purpose of this operation is to remove
the sizing from the cloth.

Mordant a piece of white cotton cloth by soaking it in
an aluminum sulphate solution, wringing, then dipping in
ammonium hydroxide solution. Wring again. Where is
the precipitate of aluminum hydroxide ?

Both this cloth and a piece of the unmordanted cloth
are to be boiled in a solution of logwood. Boil the un-
mordanted piece first and take it out before putting in the
mordanted strip. After the boiling, wring and thoroughly
wash both pieces of cloth.

Repeat, using alizarine in place of logwood. What is
the U8e of a mordant f

If so directed, cut samples (2 by 4 cm.) of the three
cloths, the original, the unmordanted, and the mordanted.
Neatly arrange and attach them in your laboratory note
book, labeling them for identification.

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90 LABORATORY EXERCISES.

EXPERIMENT 55.
Dyeing — Direct Dyes.

The quantities mentioned in the following directions
are the amounts suitable for use in dyeing 10 grams of
cloth in each case.

It is suggested that the class be divided into groups
and that each group prepare and superintend the use of
one solution.

I. CONGO RED.

Apparatus. Five beakers, enameled Iron pan, Bunsen burner,
tripod, wire gauze with asbestos center, stirring rod, balance
and weights.

Material. Congo Red, sodium carbonate, sodium sulphate,
hydrochloric acid, ammonium hydroxide, white cotton cloth.

Congo Red is a direct dye for cotton goods.

(a) Place the cloth in a beaker containing very dilute
hydrochloric acid (1 to 25). Heat to boiling. Rinse the
cloth thoroughly, first in pure water, and then in water
containing a few drops of ammonia. The purpose of this
operation is to free the cloth from sizing.

(6) Prepare three solutions as follows:
0.2 gram of Congo Red in 50 c.c. of distilled water;
0.2 gram of sodium carbonate in 20 c.c. distilled water;
0.4 gram of sodium sulphate in 20 c.c. of distilled water;

Pour the three solutions into an enameled iron dish
and add 110 c.c. of distilled water.

Heat the mixture to boiling. Keep the bath gently
boiling during the dyeing of the cloth.

Cut the cloth into strips about 4 cm. long and 2 cm.
wide. Thoroughly wet one of the strips with water and

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DYEING — DIRECT DYES. 91

place it in the dye bath. Keep it in motion in the bath
for a minute or two, then remove it and wash it thor-
oughly with water. Dry the cloth and attach it to the
note book page.

Congo Red is the sodium salt of a dibasic acid. The
presence of another sodium salt, such as the sodium sul-
phate, in the bath increases the amount of dye that will
leave the bath and enter the goods being dyed. The
Congo Red is precipitated (salted out) by the addition of a
suflScient quantity of a readily soluble sodium salt, because
the increased number of sodium ions prevents the disso-
ciation of the Congo Red, thus lessening its solubility.

The minute quantities of acids in the air cause goods
colored with Congo Red gradually to become dull in color.
This is due to the liberation of the free acid of the Congo
Red. The presence of sodium carbonate in the goods
partly prevents this change.

II. PRIMULINE.i

Apparatus. Graduate, four enameled iron pans, tripods, etc.
Material. Sodium chloride, sodium carbonate, sodium nitrite,

sodium hydroxide, concentrated hydrochloric acid, primuline,

beta-naphthol, resorcin, white cotton cloth.

Primuline is a direct dye for cotton and can be con-
verted into other colors by diazotizing and developing.

Prepare the white cotton cloth as directed in (a), page
90.

Prepare the following solutions :

(a) In 600 c.c. of water dissolve 8 grams of sodium
chloride, 0.5 gram of sodium carbonate, and 0.4 gram of
primuline. This bath is to be heated.

1 Primuline is manufactured by H. A. Metz & Co., New York City.

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92 LABORATORY EXERCISES.

The following baths are to be cold when used,

(J) Dissolve 0.3 gram of sodium nitrite in 600 c.c. of
water apd just before using add 3 c.c. of concentrated hydro-
chloric acid.

' ((?) Dissolve 0.1 gram of sodium hydroxide in 25 c.c. of
water, and add 0.1 gram of beta-naphthol, warm, and when
the beta-naphthol is all in solution, add water until the
total volume is 200 c.c.

(d) Dissolve 0.2 gram of sodium hydroxide in 25 c.c. of
water. In this solution dissolve 0.1 gram of resorcin, then
add water until the volume of the solution is 200 c.c.

Heat bath (a) to boiling, add three thoroughly wet
pieces of cotton cloth, and continue the boiling for ten
minutes. Remove the cloth and wash it.

Dry one of the pieces of cloth. Place the other two
pieces in bath (J), which must be kept cold. After the
cloth has remained in bath (6) for ten minutes, remove it
and rinse thoroughly. Then place one of these pieces in
bath ((?) and the other in bath (d). Do not heat the baths.

What acid is liberated by the action af hydrochloric
acid with sodium nitrite? This acid is said to diazotize
the primuline. The action of bath (<?) and bath (c?) is
called developing the color.

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DYEING — BASIC DYES. 93

EXPERIMENT 56.

Dyeing — Basic Dyes.

Apparatus. Graduate, eleven enameled pans, five tripods oi
ring-stands with one ring, five Bunsen burners.

Note. This apparatus may be made to serve an entire class, by
dividing the class into sections, ^ach section having charge of the prepara-
tion and use of one of the baths mentioned below.

Material. Distilled water, tannic acid, tartar emetic, fuchsine,
malachite green, methyl violet, methylene blue, white cotton
cloth prepared for dyeing (cf. Experiment 55. (a), page 90).

There are a large number of basic dyes. They form
fast colors on cotton only when used in connection with
some substance called a mordant. The mordant adheres
to the fiber of the goods. The color is taken up by the
mordant, forming a substance known as a lake. In this
way the mordant causes the dye to remain fast in the
material to be colored.

Tannic acid, or a tannate, is a common mordant used to
fix dyes to cotton. When tannic acid comes in contact
with the dye, an acid is often liberated which keeps the
dye from forming a fast color, because the lake formed is
soluble in the acid. This undesirable action is avoided
by converting the tannic acid into some tannate, for
example, antimonyl tannate, which forms a very insoluble
substance (lake) in the fiber.

(a) Prepare the following baths:

(1) Dissolve 0.5 gram of tannic acid in 500 c.c. of dis-
tilled water.

(2) Dissolve 0.2 gram of tartar emetic (potassium
antimonyl tartrate) in 200 c.c. of distilled water.

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94 LABORATORY EXERCISES.

(3) Dissolve 0.1 gram of fuchsine in 200 c.c. of dis-
tilled water.

(4) Dissolve 0.1 gram of malachite green in 200 c.c. of
distilled water.

(5) Dissolve 0.1 gram of methyl violet in 200 c.c. of
distilled water.

(6) Dissolve 0.1 gram of methylene blue in 200 c.c. of
distilled water.

(6) Heat baths 3, 4, 5, and 6 to boiling and dye one
piece of cloth in each, without using baths 1 and 2. Put
the pieces of cloth into running water, placing only pieces
dyed with one color in the mtae dish. Allow them to
remain in the water while performing the remainder of
the experiment.

((?) Heat the solution of tannic acid (bath 1) to boil-
ing. Put four pieces of white cloth into it and keep
the liquid gently boiling for at least five minutes. Take
care to see that every part of the cloth is kept thor-
oughly wet by the bath. Remove the pieces of cloth,
wring them, and put them into bath 2, which need not
be heated.

Antimonyl tannate will be deposited on the fiber of
the cloth. The tannic acid is said to be "fixed." Keep
the pieces of cloth in motion in the bath for five minutes,
then remove them and rinse them thoroughly. Use the
pieces as directed in (c?).

(c?) Put one piece in bath 3, another in bath 4, another
in bath 5, and the remaining piece in bath 6. Keep the
dye baths gently boiling and allow the cloth to remain in
the bath for about a minute. Stir constantly during the
dyeing. Try to wash the color out of the mordanted

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DOUBLE SALTS. 95

cloth. Dry the pieces of cloth and mount neatly in your
note book.

Compare the fastness of the color of the mordanted
cloth with that of the unmordanted cloth.

EXPERIMENT 57.
Double Salts.

Apparatus. 100 c.c. flask, 250 c.c. beaker, two beakers,
100 CO., stirring rod, scales, funnel, tripod, wire mat.

Material. Fine iron wire, crystallized aluminum sulphate,
potassium sulphate, ammonium hydroxide, sulphuric acid,
dilute and concentrated, filter paper.

(a) Preparation of ferrous ammonium sulphate,
FeS04(NH4)2S04.6H20.

Take 60 c.c. of dilute sulphuric acid in a flask and dis-
solve in it clean iron wire as long as hydrogen is given off.
Write the equation for the formation of ferrous sulphate^
FeSO^.

While waiting for the wire to dissolve, take another
50 c.c. of dilute sulphuric acid in a beaker and neutralize
with ammonium hydroxide solution. What salt is formed ?
Write the equation.

Filter the ferrous sulphate solution into the solution of
ammonium sulphate.

Concentrate the mixed solution to one third its volume.
Add a few drops of the concentrated sulphuric acid and
set aside to crystallize.

Pour off the liquid into the bottle designated by the
instructor. Empty the crystals of the ferrous ammonium
sulphate on a filter paper in a funnel. When the crystals
have drained, dry them between sheets of filter paper.
They can be used for making the test for nitrates.

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96 LABORATORY EXERCISES,

Write the equation for the formation of ferrovs ammonium
sulphate.

(J) Preparation of potassium alum,

KaSO,Ala(SO,)8.24HaO.

(The formula is often written KAl(S04)a • 12 HgO.)

Write the equation for the preparation of potassium
alum from potassium sulphate and aluminum sulphate.

Weigh out 15 grams of crystallized aluminum sulphate,
Al2(SO,)8.18H20.

Calculate from the equation how many grams of potas-
sium sulphate are needed.

Weigh out the calculated amount of potassium sulphate
and dissolve in 40 c.c. of hot water.

In another beaker dissolve the aluminum sulphate in
40 c.c. of hot water.

Mix the two solutions and set aside to crystallize in a
place where the beaker will not be disturbed.

Write the equation for the preparation of the potassium
alum.

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TESTS FOR IRON SALTS. 97

EXPERIMENT 58.
Tests for Iron Salts.

Apparatus. Six test-tubes, test-tube rack.

Materiau Solutions of ferrous sulphate (freshly prepared),
ferric chloride, potassium ferrocyanide, potassium sulpho-
cyanate, potassium ferricyanide (crystals or solution).

Ferrous sulphate is taken as a representative of soluble
ferrous salts (Fe"*""**), and ferric chloride as a soluble ferric
salt (Fe+++).

(a) To a freshly prepared solution of ferrous sulphate
in a test-tube add a few cubic centimeters of a solution
of potassium ferrocyanide, K4Fe(CN)g. Result ?

To a solution of ferric chloride, FeClg, add a few cubic
centimeters of the potassium ferrocyanide solution. Re-
sult ? The precipitate is known as Prussian blue. Record
results in tabular form (see below).

Pour into a test-tube 5 c.c. each of ferrous sulphate and
ferric chloride solutions. Add a few drops of the potas-
sium ferrocyanide solution. Which is the dominant color ?

Is potassium ferroeyardde a test for ferrous or ferric
salts?

(J) Prepare a solution of potassium ferricyanide,
KgFe(CN)Q, by dissolving a few crystals of it in a test-
tube of water.

Add a few cubic centimeters of this solution to a solu-
tion of ferrous sulphate in another test-tube. Result ?

Try the effect of the potassium ferricyanide on a solu-
tion of ferric chloride. Result ?

Compare the two results just obtained. Would the
potassium ferricyanide he a better test for the ferrous or the
ferric salts ? Explain,

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LABOBATOBY EXEBCI8E8.

(<?) Add a solution of potassium sulphocyanate, KSCN,
to the ferrous sulphate and ferric chloride solutions.
Note effect in each case. What hind of iron salts could be
shown to he present hy the sulphocyanate test f

State the test for a ferrous salt. 0-ive the two tests for
ferric salts. There is an easy way to remember when to use
the ferrocyanide and when to use the ferricyanide. Try to
state it.

TABLE.

Iron Salts.

Potassium Febbo-
OYANiDE, K4Fe(CN)e

Potassium Fbeeicya-
NiDB, K8Fe(CN)e.

Potassium Sulpho-
cyanate, KSCN.

Ferrous sulphate
FeSO^

Ferric chloride
FeClg

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REDUCTION OF FERRIC TO FERROUS CHLORIDE. 99

EXPERIMENT 59.

Reduction of Ferric to Ferrous Chloride.

Apparatus. Burner, test-tubes» Bunsen valve as shown in the
drawing (Fig. 19), consisting of a rubber tube (a) with a slit
cut in it, attached to the glass tube {b) and having Its upper
end closed with a glass rod (c) ; 100 c.c. flask, tripod, or ring-
stand, wire gauze with asbestos center,
Materiau Solution of ferric chloride, dilute hydrochloric acid,
' Iron wire or card teeth, potassium ferrocyanide ^
solution.

To a ferric chloride solution in a flask add
hydrochloric acid and iron (card teeth or fine
iron wire). Close the flask with a Biinsen valve,
and then boil.

Test small portions of the solution until it fails
to give the test for ferric iron.

What iron salt is there now in the solution ?

Complete the equation :

FeCl3 + H(nascent) — ^ +

Write another equation to account for the forma-
tion of nascent hydrogen.

What is the object in using the Bunsen valve f

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100 LABORATORY EXERCISES.

EXPERIMENT 60.
Oxidation of Ferrous to Ferric Chloride.

Apparatus. Burner, test-tubes.

Material. Solution of ferrous chloride, dilute hydrochloric
acid, hydrogen peroxide or concentrated nitric acid, solutions
of potassium ferrocyanide and potassium ferricyanide.

To ferrous chloride solution add hydrochloric acid and
a strong oxidizing agent, preferably hydrogen peroxide
or a few drops of concentrated nitric acid. If nitric acid
is used, boil the solution. Apply the two tests for iron
salts. What kind of iron is now in solution ?

Complete the equation :

FeClg + HCl + O (oxidizing agent)— >- +

Such a change in valence as that illustrated in Experi-
ment 59 is termed reduction; that in Experiment 60 is
termed oxidation. Why f

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SILVER SALTS IN PHOTOGRAPHY. 101

EXPERIMENT 61.
Silver Salts in Photography.

Apparatus. Test-tubes, which must be clean ; dark paper.

Material. Solutions of silver nitrate (17 grams per liter),
potassium bromide (36 grams per liter), hypo (25% solution) ;
developer as follows : 1 600 c.c. water, 1 grams hydrochinone,
20 grams sodium sulphite, dry; 1 gram potassium bromide,
1 gram citric acid, 20 grams sodium carbonate, dry.

Protect the materials from the light, by wrapping a
dark paper about the test-tubes. Do not warm with the
hands. All materials must be pure and the test-tubes
mtiat be clean.

In each part, (a), (J), and ((?), the suspended silver
bromide is prepared by adding to a test-tube one fourth
full of water, not more than 1 c.c. of potassium bromide
solution and an exactly equal amount (1 c.c.) of silver
nitrate solution, mixing well^ but not shaking hard. (If
shaken hard, the bromide will become lumpy.)

(a) Expose silver bromide to the light for a few min-
utes, shaking to expose all parts equally. (The bromide
may change color, if impure.)

To the exposed bromide, add about 5 c.c. of the
developing solution. Allow the action to continue for
two minutes. Result ?

Then add about 10 .c.c. of hypo solution (fixer), and
shake well. Result ?

(6) To the suspended silver bromide (well protected
from the light) add 5 c.c. of developer. Keep in the dark
for two minutes. Result ?

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102 LABOBATOBY EXEBCISE8.

Then add about 10 c.c. of the fixer. Result?

({?) To the suspended silver bromide add about 10 c,c,
of the fixer. Result ?

TABLE.

SlLYBB BbOMIVB BXPOSBD

TO Light

SiLTSK BBOMIDBNOT
■XPOeXO TO LlOHT

Action of developer
Action of fixer

The developer is a reducing agent capable of continuing^
hut not initiatinff^ the reduction of a* silver salt.

Under what conditions is an insoluble residue (^silver)
obtained ?

" Mypo " is the last solution used in the preparation of a
negative; what is its action ?

EXPERIMENT 62.
Cyanotype or "Blue Print" Process.

Apparatus. Two test-tubes, three enameled iron pans, gradu-
ate, 100 CO. beaker.

Material. Solution of ferric chloride (one part by weight to
two and a half parts distilled water), saturated solution of
oxalic acid, distilled water, potassium ferricyanide. Parchment
Bond paper, opaque objects or stencils cut out of dark paper,
absorbent cotton.

Take about 10 c.c. each of the ferric chloride and oxalic
acid solutions and mix in a darkened room. Divide the
mixture into three parts.

Pour one part of the mixture into a test-tube and expose
to the direct rays of the sun for a few minutes.

Pour a second portion into a test-tube and keep in a
dark place for future use.

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CYANOTYPE OR ''BLUE PBINT'' PROCESS. 103

Dip a piece of absorbent cotton in the third portion.
Squeeze the cotton nearly dry and coat very lightly one
side of a piece of Parchment Bond paper. If an unsuitable
paper is used, the ferric chloride solution will soak into it
and will not wash out, but will leave yellow where white
ought to appear on the print.

Prepare a nearly saturated solution of potassium f erricy-
anide and add a few drops of it to the solution of ferric
chloride kept in the dark. Result ?

Add a few drops of the potassium ferricyanide solution
to the solution of ferric chloride which has been exposed
to the sunlight. Result ?

What is the color of the precipitate formed by the
addition of potassium ferricyanide to a solution of a
ferrous salt ? Has the same color been obtained in either
of the above results ? Mas the sunlight caused the ferric
chloride^ in the presence of oxalic acid, to . be oxidized or
reduced f The oxalic acid takes part in the reaction. Has
it been oxidized or reduced? The oxalic acid acts as a
sensitizer.

Lay some opaque object on the piece of paper coated
with the solution containing ferric chloride and expose to
the sunlight for a very short time. Develop the blue
print by floating the paper on the solution of potassium
ferricyanide for a few seconds, and then fix by thoroughly
washing with water.

Where is the deepest color developed ?

Which set of iron salts gives this color with potassium
ferricyanide? What has happened to the ferric chloride
and what was the cause of the change f

A good blue print paper can be prepared by coating a
non-porous paper with a,10^o solution of ferric ammonium
citrate and drying in a dark place. After the exposure.

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104 LABORATORY EXERCISES.

the print is developed with a solution of potassium ferri-
cyanide and fixed by washing with water.

Practically, the solutions of ferric ammonium citrate
and potassium ferricyanide are mixed and a suitable paper
is coated with the mixture, then dried and kept ready for
use. After printing, the print is developed and fixed by
washing with water.

Such a paper can be prepared by thinly coating with a
solution made according to the following formula:

SOLUTION I.
Ferric ammonium citrate (green) • 19.5 g.

Water 100 c.c.

Add ammonia until the solution has a decided color.

SOLUTION XL

Potassium ferricyanide . . . . 19.5 g.
Water 100 c.c.

Mix equal parts of the two solutions, and to ten parts of
the mixture add three parts of a saturated aqueous solution
of oxalic acid.

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CHROMIUM COMPOUNDS. 106

EXPERIMENT 63.

Chromium Compounds.

Apparatus. Two beakers (250 c.c), two test-tubes, graduate.
Material. Potassium dichromate, potassium hydroxide, sodium

peroxide, chromium sulphate or chrome alum, alcohol, dilute

nitric acid, concentrated sulphuric acid.

(a) Pulverize 10 grams of potassium dichromate and
dissolve it in 50 c.c. of water. The color of the solution
is characteristic of dichromate ions.

(J) Dissolve 10 grams of potassium hydroxide in 100
c.c. of water.

((?) Slowly add, with constant stirring, the solution pre-
pared in (J) to that prepared in (a) until the resulting
liquid is of a pure yellow color. The color is character-
istic of chromate ions.

Complete the equation :

KaCrgO^ + 2 KOH = 2 KgCrO^ +

Any strong base would produce this change.
The structural formula for potassium dichromate is K — O — Cr=0

K-_0-"Cr4o

K-Ov ^O

The structural formula for potassium chromate is /Cr/

What i% the valence of chromium in each casef

Is the process one of oxidation^ reduction^ or neither?

(ci) Add a dilute solution of nitric acid to the solu-
tion obtained in (c) until the color of the liquid shows

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106 LABORATORY EXERCISES.

that the chromate ions have beien changed to dichromate
ions.

Write the chemical equation representing the change.

Could a solution of any strong acid he used in place of the
nitric acid?

(e) Drop by drop, pour 1 c.c. of concentrated sulphuric
acid into 5 c.c. of water.

Dissolve 1 gram of powdered potassium dichromate in
10 c.c. of water and then add 1 c.c. of alcohol.

Pour the first solution into the second. Warm the
mixture gently. The green color is due to chromic ions,
from the compound chromic sulphate.

The formula for chromic sulphate is /SO4

When a dichromate is changed into a chromic salt, is the
change one of oxidation or of reduction f

(/) Add sodium peroxide, a little at a time, to 1 gram
of chromium sulphate or chrome alum dissolved in 25 c.c.
of water until the yellow color characteristic of chromate
ions has been produced.

What element is liberated when sodium peroxide is added
to water? What base is formed?

What change takes place when a chromic salt is oxidized in
the presence of a base ?

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SEPARATION OF LEADy SILVER^ AND MERCURY. 107

EXPERIMENT 64.

Qoalitatiye Separation of Lead^ Silver, and Mercury.

Apparatus. Test-tubes, test-tube rack, funnel.
. Material. Hydrochloric acid (concentrated and dilute), nitric
acid (concentrated and dilute), ammonium hydroxide, solu-
tions of lead, silver, and mercurous nitrates, potassium chro-
mate solution, copper strip, filter paper.

(a) In one test-tube take 10 c.c. of a solution of lead
nitrate; and in another, 10 c.c. of a solution of silver
nitrate. To both test-tubes add dilute hydrochloric acid
till the action is complete. Result ? Write the equations.

Allow the precipitates to settle and then pour off the
supernatant liquid from each of the two test-tubes. Add to
the precipitates in the test-tubes enough cold water nearly
to fill the tubes, and shake the contents. Again let the pre-
cipitates settle and then pour off the supernatant liquids.

What compound has been removed by washing the precipi-
tate and then pouring off the supernatant liquid?

Try the effect of hot water on the precipitate of lead
chloride. Result ? Divide the precipitate of silver chlo-
ride between two test-tubes. With one part try the effect
of hot water; with the other, the effect of ammonium
hydroxide. Results ?

(6) To 10 c.c. of a solution of mercurous nitrate,
HgNOg, add dilute hydrochloric acid till the action is
complete. Result ? Write the equation.

Wash the precipitate with cold water and divide it
between two test-tubes. Find out whether hot water
dissolves the mercurous chloride. What effect does am-
monium hydroxide have upon the mercurous chloride ?

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108 LABORATORY EXERCISES.

(c) In the same test-tube take 5 c.c. eacli of solutions
of silver, lead, and mercurous nitrates. Add dilute hy-
drochloric acid till precipitation is complete. Of what
does the precipitate consist?

Filter. Wash the precipitate on the filter paper with
a very little cold water. Next wash the precipitate thor-
oughly with hot water, keeping the washings. Which one
of the chlorides was dissolved hy the hot water ? To confirm
this add to the hot filtrate a solution of potassium chro-
mate, K^CrO^. This chromate gives an insoluble and
characteristic compound of the metal whose chloride is
soluble in hot water. Write the equation for this confirma-
tory test. Give name^ formula^ and color of the character-
istic compound formed.

Wash the precipitate remaining on the filter paper with
ammonium hydroxide, keeping the washings. Which
chloride gives the color? What chloride is contained in the
ammonium hydroxide filtrate ? Prove the presence of this
chloride by adding a slight excess of nitric acid. Name
the precipitate and state the characteristic properties by
which you recognize it.

To dissolve the precipitate still remaining on the filter
paper, add a little aqiui regia (9 drops concentrated hydro-
chloric acid to 3 drops concentrated nitric acid). Dilute
with water the solution thus obtained, and put into it a
bright strip of copper. After several minutes, remove
the strip, and wash and rub it. Result? Eocplain why
this dissolving in aqua regia and the addition of a copper
strip is a confirmatory test.

(ci) Obtain from the instructor an unknown solution.
Using the methods in ({?), analyze the solution for lead,
silver, and mercur3^ Record all the steps, even those
giving negative results.

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BAKING POWDERS. 109

ISZPERIMENT 65.
Baking Powders.

Apparatus. Test-tubes, one-hole rubber stopper carrying
doubly bent delivery tube, 100 c.c. flask with cork to fit,
evaporating dish, mortar and pestle, ring-stand with one ring, .
burner, wire gauze with asbestos center, blowpipe, and plaster
block.

Material. Thoroughly dried baking soda, cream of tartar,
and corn starch ; lime-water, potassium iodide solution of
iodine ; acetic, dilute hydrochloric, concentrated nitric, and
concentrated sulphuric acids; solutions of ammonium hy-
droxide, sodium hydroxide, barium chloride, cobalt nitrate,
ammonium molybdate, and ammonium oxalate ; litmus paper.

I. Preparation. — Baking powder is made by mixing
sodium bicarbonate, baking soda, NaHCOj, and acid
potassium tartrate, cream of tartar, KHC^H^Og. Starch
is usually added to keep the mixture dry.

Weigh out 7 grams of cream of tartar. Then calculate
the amount of baking soda needed, if one molecule of
soda is required for every molecule of cream of tartar.

Weigh out the cream of tartar and mix thoroughly on
paper or in a mortar with the soda. Add 2 grams of
corn starch and mix thoroughly.

Put half of the mixture in a test-tube provided with a
rubber stopper carrying a delivery tube arranged for pass-
ing a gas into another test-tube half full of lime-water.

Add a few cubic centimeters of water to the baking
powder and replace the stopper. Results ? Complete the
equation :

NaHCOj + KHC^H^Oe -^ NaKC^H^O^ -j- ...-)- ...
baking powder cream of tartar Rochelle salts

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110 LABORATOBT EXERCISES.

II. Qualitative Examination of Baking Powder. — Bak-
ing powders always contain sodium bicarbonate and
some substance of acid reaction, as KHC^H^O^,
CaHPO^, KHSO^, NH4A1(S0^)2 ; and a diluting mate-
rial, as starch. In addition to these, calcium sulphate
(CaSO^) and ammonium (NH^) compounds are some-
times added.

Examine some baking powder for the materials just
given by making the following qualitative tests:

(a) Starch. — Take a pinch of baking powder and shake
it in a test-tube with cold water. Filter. Wash residue
on filter paper with cold water. Then boil the residue
with water and allow the liquid to cool. Then add a few
drops of a dilute potassium iodide solution of iodine. A
blue color indicates starch.

Put a teaspoonful of the powder into a small flask and
add a test-tubeful of water. Cork the flask and shake
contents vigorously for several minutes. Filter the liquid
to remove the starch. Take 5 c.c, of the filtrate for each
of the following testSy (6), (c), (ci), and (e).

(6) Tartrates. — Evaporate to dryness in an evaporat-
ing dish 5 c.c. of the filtered liquid with a few drops of
concentrated sulphuric acid. If a tartrate is present, the
mass will char and give an odor like burnt sugar.

(c) Sulphates. — To 5 c.c. of the filtered solution add
dilute hydrochloric acid and barium chloride to determine
whether a sulphate is present.

(d) Phosphates. — To 5 c.c. of the filtered solution add
half as much concentrated nitric acid. In another test-
tube put 2 c.c. of ammonium molybdate solution, and add
several drops of the nitric acid solution. Warm the

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BAKING POWDERS. Ill

mixture gently and allow it to stand. A yellow precipitate
indicates a phosphate.

(e) Ammonium. — Boil 5 c.c. of the filtered solution
with an equal volume of sodium hydroxide solution. If
an ammonium salt is present, ammonia will be given off.
This gas can be recognized by its odor and by its effect on
moist litmus.

(/) Aluminum. — Heat a little of the baking powder
on a plaster block before a blowpipe flame. Moisten the
residue with a solution of cobalt nitrate and heat again.
A blue color indicates aluminum.

(^) Calcium. — Treat a little of the baking powder
with dilute hj'^drochloric acid. Filter and add ammonium
hydroxide in excess to the filtrate. Test with litmus.
Then add acetic acid in very slight excess (litmus test)
and boil. Filter, if necessary, and add ammonium oxalate.
A white precipitate indicates calcium.

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112 LABORATORY EXERCISES.

EXPERIMENT 66.
Fermentation.

Apparatus. Two-liter bottle or flask, one-hole rubber stopper to
fit, doubly bent delivery tube, distilling flask, thermometer,
condenser, watch glass, test-tube, ring-stand, clamp, burner.

Material. Molasses (good kettle-rendered), compressed
yeast, lime-water, quicklime, iodine, sodium hydroxide
solution.

(a) In an acid bottle or large flask place a mixture of
one part by volume of molasses to four parts of water.
Break up two yeast cakes and shake them with luke-
warm water until they are thoroughly disintegrated.
Add the yeast to the molasses solution. The solution
thus prepared will serve for the entire class.

Close the mouth of the bottle with a single-hole stopper
with a doubly bent delivery tube dipping into a wide-
mouth bottle or beaker of water.

Describe the action and change which takes place in
the fermenting mixture.

(J) Replace the bottle of water with a test-tube of
lime-water. Result? Allow the flask and contents to
remain in a warm place for several days.

((?) Siphon off a portion of the fermented liquid and
distill it. Note the temperature of the vapor when the
liquid commences to boil and stop the distillation as soon
as the temperature reaches 98". Empty out the undis-
tilled liquid in the flask.

Place in the distilling flask a number of small lumps of
quicklime. Pour the first distillate back into the flask
and redistill it, noticing the temperature of the vapor.
Why 18 the lime usedf

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FERMENTATION. 113

Identify the second distillate by bringing a lighted
match to a small portion in a watch glass, and by apply-
ing the iodoform test to another. To make the iodoform
test, add to the liquid to be tested a little sodium hydrox-
ide solution, and then iodine, a crystal at a time, and
warm. Stop the addition of the iodine before a per-
manent brown color is obtained. The iodoform will sepa-
rate as a yellow precipitate and can be recognized by its
odor.

The cane sugar (which molasses contains) during the
process of fermentation is converted into glucose and
levulose (fruit sugar). The glucose (C^H^gO^) under-
goes further decomposition.

What gas is liberated during the fermentation f What
other compound is formed?

CeHjA^-CjH,OH +

Ethyl alcohol boils at 78" (7. Sow do you explain the rise
in the boiling point during the distillation f

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114 LABORATOBT EXERCISES.

EXPERIMENT 67.

Preparation of an Ethereal Salt (Ester).

Apparatus. Burner, test-tube.

Material. Sodium acetate, concentrated sulphuric acid, al-
cohol.

Dissolve about a gram of sodium acetate in a very little
water, and then add a few drops of concentrated sulphuric
acid. What add would be made by the combination? To
the test-tube now add a few drops of alcohol. Warm
and notice the odor of ethyl acetate. Write the equation
to show its formation:

CgH^OH (alcohol) -|- (acetic acid) — >- (ethyl acetate) + ••

EXPERIMENT 68.

Soap Bfaking.

Apparatus. Burner, ring-stand, evaporating dish, stirring rod.
Material. Beef suet or other fat, or palm, olive, or cotton-
seed oil ; alcohol, 50 % solution of sodium hydroxide.

Place in a porcelain dish 2 c.c. of fat broken up into
small bits, or a teaspoonful of cotton-seed or palm oil.
Add 8 c.c. of alcohol and 15 drops of a 50^ solution of
sodium hydroxide. Heat very gently, stirring constantly.
Continue heating until the odor of alcohol is no longer
perceptible and the contents of the dish is a pasty mass.

The alcohol is used as a common solvent for the fat and
the alkali. It is not essential to the process, but is intro-
duced in this experiment to save time. In practical
operations a water solution of sodium hydroxide is used
instead of an alcoholic solution.

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TE8T8 FOB NUTBIENT8. 115

Beef fat is mainly glyceryl stearate, C8H5(CigH8502)3.
Stearic acid has the formula H(Ci8H8502). Write the
equation for the reaction between the glyceryl stearate and
the sodium hydroxide^ producing sodium stearate (soap) and
glycerine. The residue left in the dish is soap.

EXPERIMENT 69.
Tests for Nutrients.

Apparatus. Seven test-tubes, Bunsen burner, unglazed paper,

sand bath or pie tin.
Material. White of q^, glucose, starch, suet, flaxseed, olive

oil. Concentrated nitric acid, ammonium hydroxide, Feh-

ling's solution (made from tablets), solution of iodine in

potassium iodide.

Foods are made up largely of three classes of materials:
albumens, carbohydrates (of which sugar and starch are
examples), and fats and oils.

(a) In separate test-tubes place 1 c.c. each of white of
Qgg^ glucose, and starch. To each add 15 c.c. of water
and shake until the contents of each tube is thoroughly
mixed. Note and record the appearance of each in a
tabular form like that given on page 117.

Cautiously heat each tube until the liquid boils. Re-
cord results in table. Divide the contents of each tube
into two parts; use one set for the test immediately follow-
ing and save the other set for the test in (J).

Pour off the liquids remaining in the first set of tubes,
leaving any solid or jellylike matter. To the solids add
a few drops of concentrated nitric acid. Record results
as before. Wash off any excess of acid and add ammonium
hydroxide. Results ?

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116 LABORATORY EXERCISES.

White of egg constats of albumen and water. State the
tests you would make to detect the presence of albumen in a
food.

(6) To each of the second set of tubes prepared in (a)
add a drop of iodine solution. Record the results in your
table.

Try the iodine solution on dry, raw starch. Result?

Describe a characteristic test by which starch could he
recognized in a food.

(<?) Dissolve 1 c.c. of glucose in 10 c.c. of water. Add
to it an alkaline solution of copper sulphate {Fehling'^s
solution^. Boil the contents of the tube and note the
final color. Record in the table. The result is charac-
teristic of glucose or grape sugar, and is sometimes given
by sugar of milk (also by other reducing agents).

Outline a test for glucose.

(d) On sieparate pieces of white unglazed paper place a
drop of white of egg^ a pinch of starch, a bit of glucose,
some flaxseed, a drop of olive oil, and a bit of suet.

Place the pieces of paper on an iron sand bath (or on a
pie tin) and heat cautiously with a small flame until the
suet is melted. Record results in the table.

Q-ive a test for a fat or oil.

(«) Test the food sample given you, for the presence
of each of the above nutrients*

The test for mineral (inorganic) substances in food
consists in heating the food strongly in an evaporating
dish or crucible until every trace of black * (carbon) dis-
appears. A white residue remains. This test should be
carried out only under a hood with good draft.

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ANALYSIS OF MILK FOB NUTRIENTS.

117

TABLE.
Underline characteristic results.

Nutrient

Effect of

DlBSOLVINO

BOILINO

NlTEIO
AOID

Ammonium
Hydroxide

Iodine

Feh ling's
Solution

Heating
ON Paper

ISZPERIMENT 70.
Analysis of Milk for Nutrients.

Apparatus. Evaporating dish, three test-tubes, unglazed paper,
Bunsen burner, ring-stand with one ring, wire gauze, iron pan,
graduate or cylinder, lactometer or hydrometer.

Material. Milk, Fehling's solution, iodine solution, nitric acid,
ammonium hydroxide solution, concentrated sulphuric acid.

(a) Heat 50 c.c. of milk in an evaporating dish.
What is the substance which forms on the top of the
milk 7 What nutrient in milk is shown by this coagulation f
Make a different test for the same nutrient to confirm
your opinion, and record results.

(6) To 5 c.c. of milk in a test-tube add Fehling's
solution and boil. Results? For what nutrient is
Fehling's solution a test ? Does milk contain this nutrient f
(Class discussion.)

(<?) To 10 c.c. of boiled milk, from (a), add 5 c.c. of
iodine solution. Result? What does this test show re
yarding the composition of milk ?

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118 LABOBATOBT EXERCISES.

(jX) Let fall a few drops of unboiled milk on a sheet of
unglazed paper. Heat it gently on an iron pan. Result ?

What nvtrients are contained in milk?

(e) In a graduate or cylinder of milk the instructor
should place a lactometer, to show the specific gravity of
the fluid. Normal milk is 82% to 90% water.' A specific
gravity lower than 1.027 (lactometer reading 27) indicates
an excess of water.

(/) Formaldehyde is sometimes used as a preservative
in milk. If present in proportions less than 0.05 % down
to 0.002 %, its presence may be detected by the following
test:

Dilute the milk with an equal volume of water. To 10
c.c. of this mixture in a test-tube, add carefully, without
mixing, 2 c.c. of concentrated sulphuric acid. If formal-
dehyde is present, a violet ring will be formed at the
junction of the two liquids; if not, there will be a slight
greenish tinge.

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ANALYSIS OF FLOUR FOR NUTRIENTS. 119

EXPERIMENT 71.
Analysis of Flour for Nutrients.

Apparatus. Evaporating dish, three test-tubes, unglazed paper,
ring-stand with one ring, Iron pan, Bunsen burner.

Material. Flour, Fehling's solution, Iodine solution, nitric
acid, ammonium hydroxide solution, cheese-cloth, string.

(a) Place a spoonful of flour in a piece of cheese-cloth.
Gather up the corners of the cheese-cloth and tie a string
around them so as to form a closed bag.

Place the bag in an evaporating dish of water and knead
the bag until the milkiness of the water no longer in-
creases. Remove and open the bag. Allow cold water
from the faucet to run over the contents remaining in
the bag as long as the washings remain milky. Allow the
contents of the evaporating dish to settle, then carefully
drain off the liquid.

(J) Divide the contents of the bag into three parts and
test them for albumen, glucose, and starch, respectively.
Results ?

Repeat the tests with the solid left in the evaporating
dish. Results? What was the object of using the hag ?

(e) Test some dry flour for the presence of oil or fat.

What nvtrients are contained injlourt

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APPENDIX.

X. ATOMIC WEIGHTS OF THE IMPORTANT ELEMENTS
Approximate. — For Use in Calculations.

Alaminam

Lead

207

Antimony

120

Lithium

Arsenic

Magnesium

24.3

Barium

137

Manganese

Bismuth

208

Mercury

200

Boron

Nickel

58.7

Bromine

Nitrogen

Cadmium

112

Oxygen

Calcium

Phosphorus

Carbon

Platinum

195

Chlorine

35.5

Potassium

Chromium

Silicon

Cobalt

Silver

108

Copper

63.6

Sodium

Fluorine

Strontium

Gold

197

Sulphur

Hydrogen

Tin

119

Iodine

127

Zinc

Iron

121

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122

APPENDIX.

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I

A
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rani88«;oi

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APPENDIX. 123

m. GENERAL RULES FOR SOLUBILITT.

Certain generalizations can be made concerning compounds
shown in the table on the opposite page. The exceptions to
these generalizations are few and unimportant.

1. All sodium, potassium, and ammonium compounds are
soluble in water.

2. All nitrates, chlorates, and acetates are soluble in water.

3. All chlorides are soluble, except those of silver, mercury
(mercurous), and lead (lead slightly soluble).

4. All sulphates are soluble, except those of barium, lead, and
calcium (calcium slightly soluble). The silver and the mer-
curous sulphates are only moderately soluble.

5. All carbonates are insoluble, except those of sodium, potas-
sium, and ammonium.

6. All oxides and hydroxides are insoluble, except those of
ammonium, sodium, potassium, and barium ; calcium hydroxide
is slightly soluble.

IV. VOLATILIT7 OF COMPOUNDS THAT MAT RESULT
FROM DOUBLE DECOMPOSITIONS.

1. Compounds volatile at ordinary temperatures :

HCl HBr HF BS

2. Compounds decomposing at ordinary temperatures yield-
ing volatile products :

H2CO3 — ^HaO+COg
H2SO3— ^-H^O+SOs
NH4OH — ^ H2O +NH8

3. Compounds volatile at varying temperatures below 338**
(boiling point of sulphuric acid) :

Boiling Boiling

Point. Point.

HA 100° HNOa, 86°

HCl (aqueous solution), 110° HNO3 (aqueous solution), 120°
HBr (aqueous solution), 126° HC^HsOa, 118°

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124

APPENDIX.

V. THE METRIC SYSTEM AND ITS EQUIVALENTS.
A. Fundamental Units.

The International Standard Meter is the distance between
two lines, at (f Centigrade, on a platinura-iridiura bar deposited
at the International Bureau of Weights and Measures near
Paris, France.

MEASURES OF LENGTH.
10 millimeters (mm.)=l centimeter (cm.)
10 centimeters =1 decimeter (dm.)

10 decimeters =1 meter (m.)

The International Standard Kilogram is the weight of a
mass of platinum-iridium deposited at the International Bureau
of Weights and Measures.

The liter is equal to a cubic decimeter and it is measured by
the quantity of distilled water which, at its maximum density
(4° Centigrade), will counterpoise the standard kilogram.

Since a liter contains 1000 cubic centimeters, one cubic centi-
meter of water, at 4° Centigrade, weighs 1 gram.

Important Metric Relations.

Measure.

Relation.

Linear

millimeter
centimeter
decimeter

= 0.001 meter
= 0.01 meter
= 0.1 meter

Capacity

cubic centimeter

= 0.001 liter

Weight

milligram
centigram
decigram

= 0.001 gram
= 0.01 gram
= 0.1 gram

kilogram

= 1000 grams

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APPENDIX.

125

C. Comparison of Metric with other Weights and Measures.

MsTRio Unit.

Eqihvalejit.

Approximate.

Exact.

Meter

Centimeter

Liter

Kilogram

Gram

0.4 inch
1.06 quarts
2.2 pounds
15.4 grains

39.37 inches
0.3937 inch
1.05668 quarts
2.20462 pounds

15.43236 grains

U.S. Linear
U.S. Linear
U.S. Liquid
U.S. Avoirdupois
U.S. Avoirdupois

Equivalent.

Unit

U-8 MSABITKE

Approximate.

Exact

Yard

Linear

0.9 meter

0.914402 meter

Inch

Linear

2.5 centimeters

2.54001 centimeters

Gallon

Liquid

3.8 liters

3.78543 liters

Quart

Liquid

0.95 liter

0.94636 Hter

Fluid ounce

Liquid

29.6 C.C.

29.574 C.C.

Pound

Avoirdupois

0.45 kilogram

0.45359 kilogram

Pound

Avoirdupois

453.6 grams

453.59 grams

Ounce

Avoirdupois

28.3 grams

28.3495 grams

Grain

Avoirdupois

0.06 gram

0.0648 gram

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126

APPENDIX.

VL PRESSURE OF WATER VAPOR, OR AQUEOUS
TENSION.

(In millimeters of mercury.)

Tempebatubb.

Pbbssttbb.

TBMPERATinUC.

Pbbssttbx.

0.0° c.

4.6 mm.

21.5° C.

19.1 mm.

6.5

19.7

9.2

22.5

20.3

10.5

9.5

20.9

9.8

23.5

21.5

11.5

10.1

22.1

10.5

24.^

22.8

12.5

10.8

23.5

11.2

25.5

24.2

13.5

11.5

25.0

11.9

26.5

25.7

14.5

12.3

26.5

12.7

27.5

27.3

15.5

13.1

28.1

13.5

28.5

28.9

16.5

14.0

29 .

29.8

14.4

29.5

30.7

17.5

14.9

31.6

15.4

54.9

18.5

15.9

92.1

16.4

149.2

19.5

16.9

233.8

17.4

355.4

20.5

17.9

626.0

18.5

100

760.0

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LIST OF SUPPLIES.

The following list is an estimate of the material advisable
to purchase for a class of ten pupils, provided each student
performs all of the experiments described. It names a gen-
erous supply of apparatus and chemicals, a reasonable amount
of breakage having been allowed for.

In case of somewhat expensive apparatus it has been
assumed that two pupils will use one piece of apparatus.
Provision has been made for schools not having laboratories
equipped for the use of the electric current.

In many schools it is practicable to arrange the laboratory
work so that all of the members of the class do not perform a
certain experiment at the same time. In such cases, the num-
ber of expensive pieces of apparatus required may be less than
that mentioned in the list.

GENERAL APPARATUS.

6 pieces apparatus, electrolytic.

Form shown on page 26 of First Principles of Chemistry can be pur-
chased from Eimer and Amend, New York. Form shown on page
14 of the Laboratory Exercises can be made from material given in
the list.

1 doz. sheets asbestos, thin (baking-sheet).
10 squares asbestos, 6" x 6".

2 balances, platform, with weights for weighing from 1000

grams to 0.1 gram.
10 balances, horn pan, 7|" beam, with weights for weighing
from 100 grams to 0.01 gram.
127

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128 APPENDIX.

1 barometer.

10 blowpipes, 8".
10 brushes, test-tube.
10 brushes, small tube.
10 burners, Bunsen.
20 candles, birthday.

10 capsvdes, brass, with wire holder and brass ramrod, for
holding sodium below water.

These can be obtained from Eimer and Amend, New York. Direc-
tions for making the capsule, ramrod, and holder are given on page
vi of the General Suggestions.

10 c^Us, galvanic, dichromate.

2 pkg. cigar lighters, wood.

20 clamps, iron, small ; for test-tubes, burettes, etc.

10 clamps, iron, large ; for Liebig condensers.

10 compasses, magnetic, small.

1 gross corks, assorted sizes, long.

1 set cork borers, 6 in set.

12 crucibles, porcelain, with lids, # 00.

12 dishes, porcelain, evaporating, ^ 0.

10 dishes, porcelain, evaporating, ^ 1.

10 droppers, medicine.

10 files, round, 5".

10 files, triangular, 5".

10 pr. forceps, iron, 4".

10 squares gauze, iron wire with asbestos center, 5" x 5".

1 glass cutter.

10 holders, test-tube.

1 lactometer (or hydrometer).

6 magnifiers, Coddington lens, or other make.

5 mortars, with pestle, 3^''.

12 pans, agate, shallow, 1 qt.

10 pans, iron, 6 in., shallow form, " sand bath."

10 pkg. paper, filter, qualitative, good quality, 4".

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LIST. OF SUPPLIES. 129

2 sheets paper, black, glazed.
20 pinch-cocks, Mohr's, medium.

4 sq. in. platinum foil, medium.
10 ft. platinum wire, # 25.

10 racks, test-tube, for 12 tubes.

5 sheets sandpaper, ^ 1.

10 spoons, deflagration, diam. of bowl 1 cm.

10 stands, iron, ring, 3 rings.

2 lbs. stoppers, rubber, assorted sizes, # 0-5, one- and two-
hole.

1 pkg. tapers, wax.

10 thermometers, chemical, 0°-250° C.

1 spool thread, # 50, cotton.

10 tripods, iron, for supporting dishes over burner, ring ^''
in diam.

10 triangles, pipe-stem, size to support ^ 00 porcelain cru-
cible.

10 troughs, pneumatic.

50 ft. tubing, rubber, inside diam. ^".

20 ft. tubing, iiibber, inside diam. f ".

GLASSWARE.

1 lb. beads, glass, small.

24 beakers, 100 c.c.

36 beakers, 150 c.c.

36 beakers, 250 c.c.

12 beakers, 500 c.c.

60 bottles, tincture, 1 oz. (for flame tests), corks to fit.

100 bottles, reagent, 4 oz.

20 bottles, salt-mouth, 1 oz., with two-hole rubber stoppers

to fit.
50 bottles, salt-mouth, 6 oz., with two-hole rubber stoppers to fit.
20 bottles, salt-mouth, 8 oz., with two-hole rubber stoppers to

fit.

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130 APPENDIX.

10 bottles, salt-mouth, 16 oz., with two-hole rubber stoppers to fit.

10 bottles acid, 2^ liters.

20 burettes, 50 c.c., graduated to r}^ c.c., complete.

10 condensers, Liebig, 15".

12 flasks, distilling, 250 c.c.

6 flasks, distilling, 500 c.c.

12 flasks, Florence, 100 c.c, with one- and two-hole rubber

stoppers to fit.
12 flasks, Florence, 250 c.c, with two-hole rubber stoppers

to fit.
12 flasks, Florence, 500 c.c, with two-hole rubber stoppers

to fit.
12 flasks, Erlenmeyer, 60 c.c
24 flasks, Erlenmeyer, 100 c.c.
12 flasks, Erlenmeyer, 250 c.c, with two-hole rubber stoppers

to fit.
24 funnels, accurate 60°, 2^".
10 graduates, 50 c.c, graduation marks to 1 c.c
5 graduates, 500 c.c, graduation marks to 5 c.c.
2 graduates, 1000 c.c, graduation marks to 10 cc
10 jars, battery, about 6" x 8".
10 jars, hydrometer, 12" x 2".
4 doz. jars, fruit, quick-sealing, pint.
40 plates, glass, 2| X 2^".
10 plates, glass, 4" x 4".
40 plates, cobalt glass, for flame tests, 3" x 2''.
15 retorts, tubulated, with ground-glass stopper, 4 oz.
1 lb. rods, 3 mm. diameter.
10 tubes, calcium chloride, 6", with one-hole rubber stoppers

to fit.
10 tubes, gas measuring, 60 cc, graduated to -^ c.c.

15 tubes, test, hard glass, for ignition, 6" x |", with one-hole

cork stoppers to fit.

16 doz. tubes, test, soft glass, medium walls, for heating,

6" X I".

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L18T OF auppLim. 131

2 doz. tubes, test, soft glass, medium walls, for heating,

4" X i".
16 tubes, thistle, 10", stem 3^" in diameter.
12 tubes, U, 6", with two-hole rubber stoppers to fit.
12 tubes, U, 4", with one-hole rubber stoppers to fit.
2 lbs. tubing, soft glass, medium walls for bending, outside

diameter 4 mm.
24 watch glasses, diameter 3".
40 watch glasses, Syracuse form, diameter 3".

CHEMICALS AND OTHER SUPPLIES.

1 lb. acid, acetic, 30 %, c.p.

2 oz. acid, boric, c.p.
1 oz. acid, citric, c.p.

12 lb. acid, hydrochloric, c.p., sp. gr. 1.19.

7 lb. acid, nitric, c.p., sp. gr. 1.42.
1 lb. acid, oxalic, cryst., c.p.

9 lb. acid, sulphuric, c.p., sp. gr. 1.84.

1 oz. acid, tannic, c.p.

2 qt. alcohol, ethyl, 95%.
4 oz. alizarine, paste, 25 fo-

2 oz. aluminum chloride, c.p.

8 oz. aluminum sulphate, cryst.
1 lb. ammonium carbonate, c.p.
1 lb. ammonium chloride, c.p.

10 lb. ammonium hydroxide, c.p., sp. gr. 0.9.

1 oz. ammonium molybdate, cryst, c.p.
8 oz. ammonium nitrate, cryst, c.p,

2 oz. ammonium oxalate, cryst, c.p.
4 oz. ammonium sulphate, c.p.

1 oz. antimony, lumps (powder, if necessary, just before using)
\ lb. each baking powder, several brands.
1 lb. barium chloride, cryst, c.p.
4 oz. barium nitrate, c.p.

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132 APPENDIX.

2 oz. barium sulphate, c.p.

1 oz. beta^naplithol.

1 lb. boneblack.

10 oz. bromine.

1 oz. cadmium nitrate^ c.p.

5 lb. calcium carbonate, marble chips.

1 lb. calcium chloride, granular, for drying tubes.

2 oz. calcium nitrate, c.p.

2 lb. calcium oxide, good quality of lime in tin can.

5 lb. calcium sulphate, plaster of Paris, fine.

1 lb. carbon disulphide.

12 blocks charcoal, for blowpiping.

1 oz. charcoal, wood, powdered.

1 lb. chloroform.

2 oz. chromium sulphate, c.p.

^ yd. cloth, calico, bleachable color, for bleaching with chlorine

1 yd. cloth, cotton, bleached, fine goods. •

2 yd. cheese-cloth.

1 oz. cobalt nitrate, cryst., c.p.
10 grams congo red.

10 sq. in. copper gauze, 80 meshes to inch.
4 oz. copper foil, -j^" thick.

2 lb. copper rivets, ^".

^ lb. copper sheet, ^^" thick.
2 lb. copper turnings, clean, fine.
1 lb. spool copper wire, # 16.
1 lb. spool copper wire, #18.
1 lb. spool copper wire, # 24.
1 lb. spool copper wire, #30.
1 oz. copper oxide, powdered, c.p.
1 oz. copper oxide, wire form.
1 oz. copper sulphate, anhydrous.
1 lb. copper sulphate, cryst., c.p.
1 oz. cotton, absorbent
1 oz. cosine.

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LIST OF SUPPLIES. 138

1 oz. Fehling's solution tablets.

1 oz. flaxseed.

10 grams fuchsine.

8 oz. glucose.

4 oz, hydrocMnone.

1 lb. hydrogen peroxide.

1 oz. iodine, resublimed.

10 oz. iron and ammonium citrate^ green (ferric ammonium

citrate).
\ lb. iron card teeth,
4 oz. iron chloride, ferric, c.p.

2 oz. iron filings, fine, clean.

1 lb. iron sulphate, cryst., c.p.

4 oz. iron sulphide, ferrous, in sticks for H^S.

1 lb. spool iron wire, ^ 16.

1 lb. spool iron wire, ^ 25.

1 lb. kaolin.

1 lb. lead nitrate, c.p.

6 lb. lead shot, # 10.

^ oz. lithium nitrate.

1 oz. litmus cubes.

i quire each, red and blue litmus paper.

4 oz. logwood, ground.

8 oz. magnesium carbonate.

8 oz. magnesium chloride, cryst

1 oz. magnesium, powder.

1 oz. magnesium, ribbon.

1 lb. magnesium sulphate, cryst.
10 grams malachite green.

2 lb. manganese dioxide, fine, granular, free from carbon.
4 oz. manganese dioxide, c.p.

4 oz. mercury.
1 oz. mercuric nitrate.
8 oz. mercuric oxide, red.
1 oz. mercurous nitrate.

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184 APPENDIX.

4 oz. mercury.

10 grams methyl violet.

10 grams methylene blue.

1 pt. molasses, good quality, kettle-rendered.

1 pt. olive oil.

24 sheets paper, parchment bond.

10 grams phenolphthalein.

^ oz. phosphorus, red.

1 oz. phosphorus, yellow.

1 lb. potassium and aluminum sulphate, alum.

1 oz. potassium antimonyl tartrate (tartar emetic).

4 oz. potassium bitartrate (cream of tartar).

10 oz. potassium bromide.

1 lb. potassium chlorate, cryst, c.p.

8 oz. potassium chloride.

1 oz. potassium and chromium sulphate (chrome alum).

8 oz. potassium dichromate.

1 lb. potassium ferricyanide.

2 oz. potassium ferrocyanide.

2 lb. potassium hydroxide, c.p., by alcohol.

2 oz. potassium iodide, c.p.

2 lb. potassium nitrate, cryst., c.p.

1 oz. potassium permanganate, c.p.

1 oz. potassium oxalate.

8 oz. potassium sulphate, c.p.

1 oz. potassium sulphocyanate, c.p.

4 oz. primuline.

1 oz. resorcin, white.

4 oz. silver nitrate, c.p.

1 oz. soap, castile, powdered.

2 oz. sodium.

4 oz. sodium acetate.

1 lb. sodium bicarbonate, baking soda.

1 lb. sodium carbonate, cryst., washing soda.

8 oz. sodium carbonate, pure, dry.

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LIST OF SUPPLIES. 135

6 lb. sodium chloride, salt, fine.

1 lb. sodium hydroxide, c.p., by alcohol.

1 lb. sodium nitrate, c.p.
4 oz. sodium nitrite.

2 oz. sodium peroxide.

8 oz. sodium phosphate, c.p.

8 oz. sodium and potassium tartrate (Rochelle salt).

2 lb. sodium sulphate, cryst.

1 lb. sodium sulphite, pure, dry.

2 lb. sodium thiosulphate (" hypo ").
1 lb. sodium tetraborate (borax).

1 lb. starch, corn.

1 lb. starch, potato.

1 oz. strontium nitrate, c.p.

1 lb. sulphur, flowers.

2 lb. sulphur, roll.

8 oz. tin, granulated.
1 sheet turmeric paper.
1 qt. vinegar, cider.

1 oz. wool, glass, fine Bohemian.
^ lb. zinc, sheet.

2 lb. zinc, granulated (mossy).
2 oz. zinc dust.

1 oz. zinc chloride.

1 oz. zinc nitrate.

1 oz. zinc oxide, by wet process.

8 oz. zinc sulphate.

A very few articles, such as flour, yeast, and other articles
of common household use, have been omitted from the above
list

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SCIENCE

First Principles of Physics

By Professor Henry S. Carhart, of the University of Michigan, and
H. N. Chute, of the Ann Arbor High School. lamo, cloth, 43a pages.
Price, |i.2S.

THE present volume is more than a revision of the authors'
popular High School Physics. It is a new book from cover
to cover. No pains have been spared to make it mechanically
the attractive volume which the increasing interest in the applica-
tions of this practical subject deserves. The cuts number 457
and will be found to constitute a prominent feature of the book.
Especial attention has been given to the language, which has
been made unusually simple and direct. The problems are nu-
merous and interesting, and in them the difficulty of the actual
arithmetical performance is reduced to a minimum, since it is
recognized that the purpose of problems is the concrete illustra-
tion of principles rather than practice in arithmetic.

Although in keeping abreast of the times the authors have in-
troduced many new features, they have been careful to retain the
general scheme of presentation, and the just proportions, which
made their former books so popular. The space given to the
various topics is such as logical presentation demands. No topic
is unduly emphasized in an effort at novelty of presentation. Each
subject is treated concisely and is divided into numerous brief
paragraphs with sub-headings, in order to aid the pupil in con-
centrating his mind on the points of fundamental importance.

It has been felt that many recent text-books in physics have
sacrificed scientific and logical presentation in the effort to inter-
est pupils by over-emphasis of some aspect of the science which
has been considered attractive. The result of the use of such
books has been a one-sided preparation and a consequent failure
to meet college requirements. The authors of First Principles of
Physics have shown that it is possible to produce a book which
is as successful as their former texts in preparing pupils for col-
lege and at the same time yields to no competing text-book of
physics in attractiveness.

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SaENCE

Laboratory Exercises in Physics

By Robert W. Fuller and Raymond B. Brownlee, Stuyvesant
High School, New York City. lamo, cloth, 335 pages. Price, 75 cents.

THIS Laboratory Manual is intended primarily to accompany
Carhart and Chute^s new First Principles of Physics^ which
it follows in the order of subjects. It is so arranged, however,
that it can be used with any modem text-book in Physics.

The Manual is the work of teachers in one of the best-equipped
high schools in the United States and will be found up to date in
every particular.

There are eighty-nine experiments in the book. These cover
a field so wide that from them may be selected a thorough course
which can be given with the apparatus found in any school. At
the same time the Look affords enough material to satisfy teachers
who have the best-equipped laboratories at their disposal.

While the experiments meet the requirements of the College
Entrance Board, particular effort has been made to adapt the
work to the needs of pupils not preparing for college.

The directions are simple and clear, and adapted to the ability
of beginners in Physics. There are full instructions on the mak-
ing of note-books.

Elements of Chemical Physics

By JosiAH Parsons CooKE. 8vo, cloth, 751 pages. Price, J^.5a

The El ements of Chemistry

By the late Professor Paul C. Freer, University of Michigan. lamo,
cloth, 994 pages. Price, ^i.oa

Chemical Tables

By Stephen P. Sharples. lamo, cloth, 199 pages. Price, |a.oa

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SaENCE

First Principles of Chemistry

By Raymond B. Brownlee, Stuyvesant High School ; Robert
W. Fuller, Stuyvesant High School ; William J. Hancock, Eras-
mus Hall High School; MICHAEL D. SOHON, Morris High School;
and JESSE E. Whitsit, DeWitt Clinton High School; all of New
York City. i2mo, cloth, 425 pages. Price, ;Jti.2S.

THIS book was prepared by the committee or teachers that
was called upon to frame the syllabus in Chemistry for New
York State. Its three fundamental features are : —

1. The experimental evidence precedes the chemical theory.

2. The historical order is followed as fer as possible in de-
veloping the theory.

3. The practical aspects of the science are emphasized.

In selecting their material the authors have been governed
wholly by what they consider its intrinsic value to the elementary
student, without reference to its traditional place in a text-book.

To give the pupil some idea of the great commercial impor-
tance of chemistry a number of typical manufacturing processes
have been described and illustrated. When a substance is manu-
factured in several ways the authors have given the process most
extensively used in this country. The commercial production of
copper, aluminum, iron, and carborundum has been described
somewhat in detail, as these are notable examples of modem
chemical processes.

An important feature is the brief summary and the test exer-
cises given at the end of each chapter.

Laboratory' Exercises to Accompany First Principles
of Chemistry

By the authors of the First Principles of Chemistry. i2mo, flexible
cloth, 147 pages. Price, 50 cents.

IN this manual are included seventy-one experiments, divided
into three groups. Group A consists of forty-four experiments
which all students should perform. Group B contains quantitative
experiments, and Group C includes several extremely interesting
experiments dealing with the practical applications of Chemistry.

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SaENCE

Household Chemistry for Girls

By J. Maud Blanchard, High School, Los Angeles, California
i2mo, cloth, io8 pages. Price, 50 cents.

THE author's purpose is to outline a strong course in chemis-
try, especially suited to girls of high school age. Though
the ultimate aim is the training of intelligent homemakers, it is a
manual of chemistry, not of domestic science. It is therefore
suitable for a purely academic high school, no less than for a
polytechnic high school, where a rigorous course in household
chemistry forms a necessary foundation for the work in domestic
science. The choice of subjects is based in a general way on the
following scheme : —

What we breathe.

What we drink and use for cleaning.

What we use for fuels and illuminants.

Chemical nature of common substances.

Foods and food values.

Adulterants and simple methods for their detection.

Textiles — care of textiles, removal of stains, etc.
The second half of the book, beginning with Experiment 28, is
devoted to qualitative experiments in organic chemistry, as delicate
quantitative experimentation is beyond the ability of high school
pupils. Supplementary reading is of course advisable in this con-
nection ; with this in view, a full list of library text-books is given,
and definite references to these accompany the experiments.

High School Physics

By Professor Henry S. Carhart, of the University of Michigan, and
H. N. Chute, of the Ann Arbor High School. New Edition, thor-
oughly revised. i2mo, cloth, 444 pages. Price, $1.2,$,

THE task of arousing interest, and of emphasizing especially
attractive aspects of the science, is looked upon as the prov-
ince of the individual teacher. This text-book aims simply at a
clear-cut statement of general principles, giving each weight
according to the scientific importance which it possesses.

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SCIENCE

Text-Book of Cooking for Secondary Schools

By Carloti'A C. Greer, East Technical High School, Cleveland
i2mo, cloth, ooo pages. Price, oo cents.

THIS is not a book of recipes — it is literally a text-book of
cooking, in which the practice of cooking is developed in a
logical manner. The methods of cooking are practical, and the
author shows the scientific principles on which they are based.
Statements^ thus involving applied science are carefully kept
within the understanding of pupils in the secondary school.

The text-book is divided into two parts. Part I treats of The
Cooking of Foods, Part II of Table Service and Food Values of
Foods, Together the two parts furnish material for one year's
work of four or five lessons a week, or for two years' work if the
curriculum provides but two lessons a week.

Part I is a guide to teach pupils to cook. The pupils follow
established recipes and are taught to consider the processes of
cooking as experiments in scientific study. Added to recipes
and directions are suggestions to aid the pupil to appreciate the
significance of each step and to understand the change that is
taking place in the substances he is using. In the reviews the
pupil is helped to work out his own scheme for preparing a meal.

Part II adds to the planning and cooking of meals a practical
method of calculating food values. Special attention is given to
cooking and serving without a maid.
* The book is richly illustrated.

The entire book has been worked out and tested in the class-
room of one of the largest vocational schools in America.

Descriptive Inorganic General Chemistry

A text-book for colleges, by the late Professor PAUL C. FREER. Revised
edition. 8vo, cloth, 559 pages. Price, $^.oo»

THIS is a text-book in General Chemistry for colleges and uni-
versities. It aims to give a systematic course of chemistry
by stating certain initial principles, and connecting logically all
the resultant phenomena.

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SCIENCE

Practical Physiography

By Dr. HAROLD W. FAIRBANKS, of Berkeley, California. 8vc, cloth,
570 pages, 403 Illustrations. Price, ^i.6a

THIS is the most attractive text-book on Physical Geography
yet published. It contains over 400 illustrations, beauti^ly
reproduced, and ten colored maps. Most of the views are from
the author's own negatives, and were taken especially to illustrate
parts of the book.

The earth is not studied as a fixed model, but as a world
whose physical features are undergoing continual change. These
changes are seen to affect the dimate and life conditions of plants
and animals, and to have important influence on the activities of
men. It is the object of the Physiography that the pupils gain
an ability to understand the meaning of the phenomena of the
land, the water, and the air, and the relation of aU life to them.

Part I treats of general physiographic processes. Part II has
to do with the physiography of the United States. The book is
intended as an aid to study — not as a compendium of infor-
mation ; consequently a description of the world as a whole is
omitted. Attention is devoted specifically to the region of the
United States, and typical examples afforded by it are studied as
representatives of world-wide processes.

No separate chapters have been devoted to the relation between
physical nature and life, but instead, this relation is brought put
in its appropriate place in connection with each topic throughput
the book.

The purely descriptive method has been discarded as far as
practicable, the object being to lead the student to investigate
and find out for himself.

Suggestive questions are distributed throughout the book in
close connection with the descriptive portions of the text to
which they refer. The object of these is to stimulate the pupil
to think for himself.

The book includes field and laboratory exercises which may
be enlarged and adapted to the needs of a particular locality.

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Physics for College Students

By Professor Henry S. Carhart, University of Michigan, 8vo^
cloth, 631 pages. Price, $2.2$.

THIS IS a new and widely successful text-book for a general
course in Physics in colleges and universities. In writing it
the author has kept constantly in mind those students who are
not necessarily scientific in their taste or choice, but who desire
a comprehensive outline of the leading features of Physics.
Mathematical difficulties have been successfully reduced to such
a degree that they may be readily surmounted by the average
college student.

The book contains a full treatment of Mechanics, Sound, Light,
Heat, and Electricity and Magnetism.

Physics for University Students

By Professor Henry S. Carhart, University of Michigan.

Part I: Mechanics, Sound, and Light. Revised edition of i9o6«
With 154 Illustrations. i2mo, cloth, 346 pages. Price, $i.So,

Part II: Heat, Electricity, and Magnetism. Revised edition of
1904. With 230 Illustrations. i2rao, cloth, 456 pages. Price, ;{ti.5a

THIS is a revised edition of the work which has for ten years
been so favorably known to professors of Physics. The two
volumes offer a more extended and more difficult course in general
Physics than the Physics /or College Students by the same author.
Only such topics have been selected as appear most important
to a general survey of the science. Somewhat more attention
than is customary is given to Simple Harmonic Motion, because
of its extensive application in Alternating Currents and its service
in Mechanics, Sound, and Light.

Although the treatment is often mathematical, mathematics is
called into service not for its own sake, but wholly for the pur-
pose of establishing the relations of physical quantities.

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BOOKKEEPING

Practical Bookkeeping

By Carlos B. Ellis, Principal of the Commercial High School
of Springfield, Massachusetts. 8vo, cloth, 256 pages. Price, 1(1.35.

THIS manual offers a complete and adequate course in book-
keeping that will enable a pupil to master the principles of
the subject and give him sufficient practice in their application to
meet the ordinary demands of business.

The method of the book is to appeal to the pupiPs intelligence,
not to his memory; to teach by explanation, not by abstract
rules.
The following are some of its distinctive features :

1. The subject is developed logically by first studying the
ledger. Since each entry in a journal or other book of original
entry is to be posted to some account in the ledger, it is mani-
fest that a pupil cannot make these entries intelligently until he
understands the accounts involved. When he understands the
use and purpose of each of the principal accounts, he is ready to
study the books of original entry.

2. No exercises are introduced simply with the purpose of
providing work and prolonging the time devoted to the subject,
but there is enough work to fit the pupil to meet the usual re-
quirements of the business office.

3. The exercises for supplementary drill cover a great variety
of difficult entries, and will be found very helpfiil.

4. Self-reliance is stimulated by special instructions for the
pupil, given at points where they will be needed. The author
has made a careful study of the pupils^ most frequent errors and
has set up " danger signals " to show how they may be avoided.

5. No attempt is made to teach any particular business, but the
several sets of transactions are designed solely to teach the prin-
ciples of bookkeeping.

6. The book is unique in its treatment of the following topics,
each of which has been prepared by an expert : The Voucher
Method ; Loose-Leaf Accounting ; Card Index Systems ; and Fil-
ing Systems.

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BOOKKEEPING

Blank Books, Forms, and Vouchers to accompany

Ellis's Bookkeeping

Blank Books.— Part I. Set of four. Price, 50 cents.
Blank Books. — Part II. Set of five. Price, 75 cents.
Business Forms. Price, 60 cents.
Incoming Vouchers. Price, 50 cents.

Blank Books for Part I Blank Books for Part U

Journal — 20 pages. Journal — 32 pages.

Cash Book and Sales Book — • Cash Book — 24 pages.

20 pages. Sales Book, Purchase Book, and

Ledger — 44 pages. Bill Book — 28 pages.

Trial Balances and Statements — Ledger — 76 pages.

48 pages. Trial Balances and Statements —

44 pages.

THESE blank books are very neat and attractive in appear-
ance, and the quality of the paper is superior. Those for
Part II have special rulings and printed headings.

Business Forms

This package contains everything the pupil will need for Exer-
cises XII to XIV. It includes a check book, a substantia] office
file, and a generous supply of stationery and forms. Care is taken
to make them seem like actual business papers.

Incoming Vouchers

These vouchers have been prepared for use with Exercises XII
to XIV, and they are numbered to correspond with the transac-
tions in the text-book. These vouchers are characterized by
simplicity and neatness of design and a businesslike appearance.

In preparing the apparatus Mr. Ellis has improved upon the
best characteristics of all similar forms.

Note. — On the outfit to accompany EUlis's Bookkeeping transporta*
tion is at the expense of the purchaser.

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MATHEMATICS

First Principles of Algebra; Elementary Course

By H. R Slaught, Associate Professor of Mathematics in the Univer-
sity of Chicago, and N. J. Lennes, Instructor in Mathematics in
Columbia University, New York City. i2mo, cloth, 288 pages.
Price, ;^i.oo.

THIS book embodies the methods of what might be called the
new school of Algebra teaching, but at the same time has
kept the valuable features of the books which preceded this
movement.

In writing the First Principles of Algebra the authors have been
governed by two main purposes: (i) to provide a gradual and
natural introduction to the symbols and processes of algebra;
(2) to give purpose to the subject of algebra by a constant use of
it in doing interesting and valuable things. Each of these pur-
poses leads to the same order of topics, which, however, differs in
minor features from the conventional order. In the Introduction
the authors offer a full explanation of their reasons for adopting
the present order, which will be found to be logical and sys-
tematic.

The study of equations and their uses is regarded as the main
topic for the first year's work. It is recognized that abstract equa-
tions will appear of little or no value to the pupil unless he finds
uses for them ; hence frequent lists of problems are provided for
translation into equations and for solution. Many of these prob-
lems involve valuable mathematical concepts, so that during the
first half year algebra is made to appeal to the higher and more
useful types of interest, and not merely to the instinct for solv-
ing puzzles, which must be the case if the greater part of this time
is spent on factoring and in manipulating complicated fractions.

The principles of algebra used in the Elementary Course are
stated in a small number of short rules, eighteen in all. The
purpose of these rules is to furnish in simple form a codifi-
cation of those operations of algebra which require special em-
phasb.

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