Household chemistry for the use of students in household arts

HOUSEHOLD CHEMISTRY

FOR THE USE OF

STUDENTS IN HOUSEHOLD ARTS

BY

HERMANN T. VULTE, Ph.D., F.C.S.

Assistant Professor of Household Chemistry in
Teachers College, Columbia University

EASTON, PA.

THE CHEMICAL PUBLISHING COMPANY

1920

COPYRIGHT, 1915 BY H. T. VULTE.
COPYRIGHT, 1920, BY H. T. VULTE.

PREFACE.

This book is presented for the general study of the
subject of chemical operations in the household. It is
designed to meet the needs of secondary schools and
colleges. For the former purpose, the instructor will
find it possible to make such selection of material as will
cover the field of work broadly in a semester. A
thorough completion of the course indicated in the book
would require the attention of the college student for one
year. It is highly advisable in this longer course that
one-third of the period be given to explanation and
discussion of the topics in the form of lectures. In
the shorter course the object may be accomplished by the
more informal conference system.

It has seemed best to include a large amount of de-
scriptive matter in this book, which was not a feature of
former editions.

I wish to express my great indebtedness to my assist-
ants, Mrs. Ellen Beers McGowan and Miss Sadie B.
Vanderbilt, for valuable assistance and advice in the prep-
aration of this volume.

H. T. V.

May, 1915.

TABLE OF CONTENTS.

CHAPTER I.

INTRODUCTORY. PAGE

Outline of Topics in Organic Chemistry I

CHAPTER II.

ATMOSPHERE AND VENTILATION.

Composition of the Air. Properties and Uses of Constitu-
ents. Experiments. Factors in Ventilation; Methods of 7
CHAPTER III.

WATER.

Physical and Chemical Properties. Classification of Drink-
ing Waters. Qualitative Examination. Purification of

Water. Hard and Soft Water. Experiments 23

CHAPTER IV.

METALS.

Metals and Alloys. Processes of Manufacture. Physical
and Chemical Properties. Effect of Acids and Alkalies.

Methods of Cleaning. Experiments 43

CHAPTER V.
GLASS, POTTERY, AND PORCELAIN.

Manufacture. Properties. Experiments 61

CHAPTER VI.

FUELS.

Classification. Solid Fuels: Nature and Properties. Liquid
Fuels: Manufacture, Nature and Properties. Gases:

Manufacture, Properties. Experiments 66

CHAPTER VII.
CARBOHYDRATES.

Classification. General Properties. Glucose. Fructose.
Galactose. Sucrose. Maltose. Lactose. Starch. Dex-
trin. Glycogen. Celluloses. Experiments and Practical
Applications 87

CONTENTS V

CHAPTER VIII.

FRUITS AND FRUIT JUICES. PAGE

Composition. Analysis of a Fruit. Experiments in Jelly
Making 122

CHAPTER IX.

FATS.

Formation and Occurrence. Properties. Experiments.
Butter; Specific Tests 128

CHAPTER X.

PROTEINS.

Classification. Occurrence. Solubilities. General and
Specific Properties. Hydrolysis. Albumins and Globu-
lins. Egg. Gelatin. Bone. Muscle. Beef Extracts.
Milk. Cheese. Experiments 140

CHAPTER XI.

BAKING POWDERS.

Composition. Comparison and Types. Experiments 169

CHAPTER XII.

TEA, COFFEE, CHOCOLATE AND COCOA.

Sources. Constituents. Methods of Preparation. Experi-
ments , 175

CHAPTER XIII.
FERMENTS AND PRESERVATIVES.

Yeast. Lactic Acid. Acetic Acid. Butyric Acid. Experi-
ments. Method of Food Preservation. Tests for Pre-
servatives. Tests for Purity of Certain Foods 182

CHAPTER XIV.
DISINFECTANTS AND DISINFECTION.

Physical and Chemical Methods of Disinfection. Antiseptics.
Tests for Disinfectants 194

VI CONTENTS

CHAPTER XV.

CLEANING AGENTS. PAGE

Classification. Soaps and Soap Powders. Manufacture of
Soap. Soap Analysis. Scouring Powders. Metal Pol-
ishes. Tests for Cleaning Agents. Bleaches, Grease and
Stain Removers. Bluing. Experiments 200

CHAPTER XVI.

VOLUMETRIC AND GRAVIMETRIC ANALYSIS.
Normal Solutions. Preparation of Solutions. Use of Indi-
cators. Analysis of Vinegar, Cream of Tartar, Baking
Soda, Household Ammonia. Analysis of Soap or Soap
Powders. Cereal Analysis. Kjeldahl Determination of
Nitrogen. Estimation of Reducing Sugar 214

CHAPTER XVII.

REAGENTS.
Methods of Preparation 228

APPENDIX.
Useful Tables. List of Apparatus 233

CHAPTER I.

INTRODUCTORY.

Courses of instruction in Household Economics group
themselves principally about foods or other materials
used in the household, most of which are of so-called
organic origin. Hence some fundamental instruction in
the nature of organic compounds is necessary, and prefer-
ably should precede a course in household chemistry,
which is largely an applied chemistry of the carbon com-
pounds. Often, however, a preliminary course in organic
chemistry cannot be introduced into the curriculum.
For that reason, an outline of a series of lessons in the
chemistry of the carbon compounds is given here, de-
signed to be presented as lectures and experiments run-
ning parallel with the work in household chemistry and
often merging into it. In such a combined course, the
outline as given will need to be adapted to the allowed
time, perhaps to the exclusion of the aromatic com-
pounds, and it may be necessary to perform many of the
experiments as demonstrations. To give the study its
proper emphasis and value, stress should be placed less
upon individual than upon type compounds, and upon
their interrelation and properties, always with a view
to enriching and making more effective the practical
knowledge which the student has of substances met in
everyday life.

It may be pointed out, in addition, that a recent course
in general chemistry of the most modern type should be
required as a prerequisite of household chemistry. In

2 HOUSEHOLD CHEMISTRY

such a course the subject matter should be so selected
that the material handled in household chemistry shall
not be entirely unfamiliar. For example, more definite
information would be useful with regard to the consti-
tution and properties of the important metallic elements,
and a few of their simpler compounds.

Outline of Course in Organic Chemistry.

I. ORIGINAL AND PRESENT MEANING OF TERM "OR-

GANIC/'

Importance of organic chemistry — Some differences
between organic and inorganic compounds — Organic
chemistry the chemistry of carbon compounds — The car-
bon atom; its valency; graphic expression of valency;
tendency to combine with hydrogen.

II. CHAIN HYDROCARBONS.

The Methane, Ethylene, and Acetylene Series.

Development of Series — Nomenclature — Common for-
mulae and differential — Properties — Occurrence of im-
portant members.

Application to Gaseous and Liquid Fuels.

Experiments: Preparation of Methane, Ethylene and
Acetylene.

Reaction for the double bond.

III. ISOMERISM APPLIED TO THE HYDROCARBONS.

Nature and effect of isomerism.

IV. SATURATION AND UNSATURATION.

Meaning of — General formation of substitution and

HOUSEHOLD CHEMISTRY 3

addition products — Isomeric forms — Formation of iodo-
form and chloroform.
Experiment : Preparation of iodoform.

V. ALCOHOLS.

Derivation from the hydrocarbon through substitu-
tion— relation to metallic hydroxides — Nomenclature —
General physical and chemical properties and reactions —
Source and uses of important alcohols — Isomeric forms ;
primary, secondary, and tertiary alcohols — Unsaturated
alcohols — Glycols and polyhydric alcohols — Sulphur
alcohols or mercaptans.

Application to liquid fuels; to carbohydrates; to fats;
to fermentation; preservation of foods.

Experiment: Preparation of ethyl alcohol.

Detection of methyl alcohol.

VI. ALDEHYDES AND KETONES.

Formation from alcohols — Comparative properties and
reactions — Name, source, and uses of important ex-
amples.

Application to carbohydrates; preservatives; flavoring
extracts.

Experiments : Preparation of formaldehyde, acetalde-
hyde and acetone.

Reduction by aldehydes, such as the Fehling's reaction.

VII. FATTY ACIDS.

Formation from aldehydes — Nomenclature — General
properties and reactions — Occurrence and properties of

4 HOUSEHOLD CHEMISTRY

important examples — Unsaturated acids : occurrence and
characteristics.

Application to fats and oils.

Experiment: Preparation of acetic acid.

Separation of a fatty acid from a fat.

Illustration of drying and non-drying property.

VIII. SCHEMATIC REVIEW OF INTERRELATION.

Hydrocarbon »-*• Substitution or Addition »— *

Alcohol •>-* Aldehyde »-* Acid

IX. ESTERS.

Formation of type esters reviewed — Waxes — Glyceryl
esters of fatty acids : general properties ; occurrence and
properties of important fats and oils.

Application to fats and oils.

Experiment: Decomposition of a fat.

Preparation of ethyl acetate.

X. ETHERS.

Formation — Analogy to metallic oxides — Nomencla-
ture— Important examples — Properties — Relation of
ethers to alcohols; of thio ethers to mercaptans.

Application: Ether extraction processes.

XL OXIDATION PRODUCTS OF GLYCOLS AND POLYHYDRIC
ALCOHOLS.

Hydroxyacids — Dicarboxylic acids — Special examples :
Glycollic, lactic, sarcolactic, oxalic, succinic, malic, tar-
taric, citric, aconitic — Sources and properties.

Application to milk; to muscle; to fruits and fruit
juices.

HOUSEHOLD CHEMISTRY 5

XII. NITROGEN COMPOUNDS.

1. A Iky I Cyanides.

Analogy to halogen derivatives — Hydrolysis of
cyanides — Other cyanogen compounds: properties and
uses of — Prussian blue as bluing.

2. Amines.

Primary, secondary and tertiary amines — Quaternary
ammonium bases — Unsaturated amines and related com-
pounds— Important examples.

3. Amides.

Structure and properties — Amides of dicarboxylic
acids — Important examples.

4. Amino Acids.

Formation — Nomenclature — Properties and reactions
Important examples — Synthesis to peptids — Relation to
proteins.

5. Proteins.

General composition, properties, etc.

6. Purin Group.

Purin ring and substituted purins — Adenin, guanin,
hypoxanthin, xanthin and uric acid; caffein; theo-
bromine. — Pyrimidin base. — Relation to nucleoproteins.

XIII. AROMATIC COMPOUNDS.

Benzene ring — Homologues — Benzene, naphthalene
and anthracene ; source and importance — Benzene deriva-
tives analogous to those of the straight chain series —
Formation of substitution products; phenols; alcohols;
aldehydes; acids; amino compounds; diazo compounds;

6 HOUSEHOLD CHEMISTRY

leuco compounds — Properties and commercial importance
of compounds — Dyes.

Experiments: Preparation and detection of benzalde-
hyde and of benzoic acid.

Detection of vanillin and saccharin and salicylic acid.

Preparation of aniline.

Diazotizing aniline.

Coupling diazos and phenols.

Formation of leuco compounds.

Reduction of indigo blue and subsequent oxidation.

Preparation of helianthin and eosin.

CHAPTER II.

ATMOSPHERE AND VENTILATION.

Probably no subject so important to life as the air we
breathe is so little understood, nor is there any other
instance of so many evils arising from ignorance. A
knowledge of the relation of pure air to health and ef-
ficiency should be a part of the education of people in
general. In no other way will there be a solution of
problems of ventilation in homes and public buildings,
or of sanitary housing in large cities, and the stamping
out of devastating diseases. A fundamental knowledge
of the properties and functions of the atmosphere, and
the principles of ventilation, is therefore all-important
for the student of household chemistry.

Composition of the Air. — Pure air is not a compound
of definite composition, but a mixture of gases. The
two most important, oxygen and nitrogen, occur in the
proportion of about 20 parts of the former to 79 of the
latter. Other essential constituents are carbon dioxide,
which in pure air averages in amount a little over 3
parts in 10,000 or 0.03 per cent, to 0.04 per cent., and
aqueous vapor. Traces of argon, krypton, neon, ozone,
hydrogen, ammonia, nitrogen acids, nitrites and nitrates,
helium, and several other substances are normally found
in varying amounts.

In addition to the above, there are always present in
ordinary air many substances classed as impurities, the
kind and amount varying with the locality. Dust from

8 HOUSEHOLD CHEMISTRY

the soil and from factory operations is found as sus-
pended matter, together with micro-organisms, pollen,
plant seeds, and soot. Offensive gases may contaminate
the air of manufacturing centers, but they are usually
more disagreeable than dangerous. The air of cities
contains anywhere from 100 to 5,000 times the amount
of dust and bacteria that is found in country air.

Properties and Uses of Constituents. — Oxygen. — Oxy-
gen is the life-supporting element for all animals and
plants. Diluted as it is with nitrogen, the oxygen of
the air is in the condition and proportion best adapted
to sustain most forms of life. In materially increased
amount it is a poison to human beings; on the other
hand, life cannot exist if the proportion falls to four-
fifths of the normal, or 16 per cent, instead of about
20 per cent.

In animal organisms, a relatively small amount of
oxygen is concerned in the process of respiration. Of
20.9 per cent, inhaled by human beings, 16 per cent, is
returned in the exhaled air, together with about 4.4 per
cent, of carbon dioxide. The oxygen used, however, in
the respiratory exchange suffices to supply heat and
energy to the body by means of oxidative processes in
the protoplasm of tissue cells.

Plants require oxygen for respiratory and other
processes as animals do. Part of the necessary amount
is inhaled; part is obtained in the process of photo-
synthesis, through the action of chlorophyll and sun-
light. A plant lacking in chlorophyll, such as a mush-

HOUSEHOLD CHEMISTRY 9

room, absorbs oxygen directly from the air; green
plants, in the presence of sunlight, build up carbohydrate
material in their cells by synthesizing carbon dioxide
and water, and in the operation release oxygen. The
cells use as much of this as they require; the excess is
returned to the air. It is estimated that an acre of
woodland withdraws in one season about 4^2 tons of
carbon dioxide from the atmosphere, and returns 3^
tons of oxygen.1 In darkness the chlorophyll becomes
inactive; the plant then takes oxygen from the air. It
is probable that the roots absorb oxygen from the soil
and from ground water.

Ozone. — Ozone is a peculiar form of oxygen which
exists as O3. It is produced from O2 by electrical
discharge, by the action of moist air on phosphorus, or
by several chemical reactions, such as the action of con-
centrated sulphuric acid on potassium permanganate.
Its odor is noticed around static electrical machines and
during thunderstorms. Ozone is a powerful oxidizing
agent, but is found only in minute quantities in ordinary
air. The salubrity of the air in evergreen forests is
ascribed to ozone, formed as a product of the slow oxi-
dation of turpentine and similar plant products.

Nitrogen. — Nitrogen is an inert gas; it does not burn
nor support combustion, and its chief value to organ-
isms is in the form of compounds. It is not utilized in
human respiration except as a diluent of oxygen. In
the plant world certain species of bacteria such as the

1 Harrington : Practical Hygiene.

10 HOUSEHOLD CHEMISTRY

micro-organisms found in the root nodules of some
legumes, carry nitrogen directly to the pea, bean or
clover. How far other plants are able to utilize atmos-
pheric nitrogen is a question. The main source of the
organic nitrogen in their tissues is the nitrogen com-
pounds in the soil due to micro-organisms, and ammonia
and nitrates washed down by the rain.

Carbon Dioxide* — Carbon dioxide is a heavy gas
which will not support combustion or respiration. It is
the result of oxidation processes, either in respiration,
fermentation, the burning of tons of fuel, or chemical
action in the soil. Harrington estimates that
5,000,000,000 tons are discharged annually into the
atmosphere. The amount of carbon dioxide in the air
may vary from two parts in 10,000, or 0.02 per cent, in
the purest air to 30, 40 or even 100 parts in bad con-
ditions of overcrowding. Only in greater amount, how-
ever, such as was found in the Black Hole of Calcutta,
is it destructive to animal life. Undiluted, it causes in-
stant suffocation by spasmodically closing the glottis.

On account of the solubility of carbon dioxide in
water, considerable amounts are taken out of the atmos-
phere by rain and go to form carbonates in the soil or
remain as carbon dioxide in the water.

Aqueous Vap'or. — The term aqueous vapor is mis-
leading and does not strictly represent the gaseous form
in which the water in question exists in the atmosphere.
The amount of aqueous vapor which a given volume of
air is capable of holding without condensation depends

HOUSEHOLD CHEMISTRY II

upon the temperature of the air. At o° C., a cubic meter
of air is saturated if it contains 4.87 grams of moisture;
at 20° C. or 68° F. it can contain 17.157 grams, and at
32° C. or about 90° F. it may hold 30 grams. It follows
that a precipitation of moisture results when the tem-
perature of vapor-laden air changes from a higher to a
lower point. The temperature at which moisture is
deposited is called the dew point.

The rate of elimination of moisture from bodies de-
pends largely on the amount of moisture already car-
ried by the air. When air is saturated, it can take up no
more; evaporation, therefore, cannot occur, and the
moisture normally given off by the human body, for ex-
ample, is deposited on the surface of the skin. This most
disagreeable condition of stickiness is associated with
days of great humidity in summer, with moist, raw days
in winter, and with overheated crowded rooms.

Humidity is measured in terms relative to the satura-
tion point of the atmosphere at any given temperature.
A relative humidity of 50 means that the air contains
only 50 per cent, of its moisture-carrying capacity at that
temperature. The limits of comfort are generally given
as between 40 and 75 ; a humidity of 75 to 100 is op-
pressive to man but beneficial to plants.

The relation of atmospheric moisture to heat is most
important. Water has a great capacity for heat and
gives it up slowly. It acts therefore as an equalizer of
the sun's heat and a moderator of temperature. In semi-
arid and desert regions, where the air is moisture-free,

2

12 HOUSEHOLD CHEMISTRY

and at high altitudes where the amount of vapor is
relatively less, extreme heat during the day and a sudden
fall of temperature at night are observed. It is esti-
mated that the absorptive and radiative power of aqueous
vapor is 16,000 times that possessed by air.

Dust. — The relation of dust to aqueous vapor is sig-
nificant. Without this suspended matter in the air there
would be little or no precipitation of moisture, but a
constant state of saturation would be possible. The
particles act as nuclei round which vapor condenses as
fog or rain. In large manufacturing cities the preva-
lence of soot and dust in the air accounts for frequent
fogs. Bacteria cling to dust particles and with them are
washed out of the air by rain.

General Properties of the Air. — Density. — The density
of the atmosphere varies, the principal factor in varia-
tion being altitude. At 3^ miles elevation it is only one-
half as dense as air at sea level and therefore exerts one-
half the pressure. The normal pressure of the atmos-
phere at sea level upon each square inch of surface is
about 15 pounds, but this pressure, which amounts to
30,000 pounds on the average body, is not appreciated,
since it is exerted equally in all directions. Air pressure
is commonly measured by the height of the column of
mercury which it is capable of supporting, the recording
instrument being called a barometer. A normal pressure
at sea level, exerted on the mercury at the base of the
barometer tube, is sufficient to raise in the tube a column
of mercury weighing 14.7 pounds. This is called a
pressure of I atmosphere.

HOUSEHOLD CHEMISTRY 13

When the mercury falls in the barometer, which us-
ually happens before a storm, it is evident that atmos-
pheric pressure has become less. This is because the
air at such times probably contains more than a normal
amount of water vapor, which is lighter than air, its
density being 9, while air averages 14.5. The term
heavy, sometimes used to describe the atmosphere in this
connection, is contrary to fact. A further explanation
of the barometric condition is found in the fact that as
different portions of the earth's surface become un-
equally heated, the warmer areas impart corresponding
heat to their atmosphere. This causes a rising and
dilation of air over a given section, the heated column
overflowing at the top upon the cooler surrounding atmos-
phere. Diminished pressure results in the rarefied
column, with consequent expansion and a fall in tem-
perature, until the moisture-precipitation point is reached,
and the contained vapor of the air is condensed as
cloud or rain. In changing from the vapor to the liquid
form latent heat is released, which increases the rare-
faction, and the upward movement and overflowing of
the air column continue. Thus is created a condition of
low pressure which the barometer indicates, while in
the surrounding areas high barometric readings will be
found. The rain area will naturally correspond with
the area of low pressure.

Diffusion. — By a fortunate provision of nature, gases
of different specific gravities do not lie in strata when
mixed, but diffuse until the mass is of uniform com-
position throughout. If it were otherwise, a layer of

14 HOUSEHOLD CHEMISTRY

carbon dioxide, which is a heavy gas, would blanket the
earth, and offensive and poisonous gaseous emanations
would make most localities uninhabitable. As it is, all
such gases diffuse through the atmosphere as soon as
produced. Stratification of the air is not, however, en-
tirely controlled by diffusion. The local movements of
air currents caused by unequal heating operate like a
motor fan and are a most potent equalizing influence.

Heat Capacity. — Air has a considerable capacity for
taking up heat, which is utilized in hot air heating.

Liquid Air. — Air can be liquefied by causing it to
escape slowly from tremendous pressure, so that much
heat is absorbed in expansion. The temperature of
liquid air is nearly 400° below zero Fahrenheit. In this
state it volatilizes rapidly at room temperature, the more
volatile nitrogen being given off first. This leaves an
available source of oxygen, which is utilized in filling
oxygen tanks. Liquid air has a faint blue color.

EXPERIMENTS ON AIR.

1. Presence of Oxygen. — Pour an inch of alkaline pyrogallol
into a short broad test tube, close with a rubber stopper, invert
and mark the position of the stopper and liquid on a gum label
pasted on the outside of the tube, shake the tube well, invert and
open under water, mark the level of the water in the tube when
open, and explain the phenomenon.

2. Carbon Dioxide. — Expose a few drops of lime-water or
barium hydroxide on a slide to the air and notice that, by the
end of the lesson, it is cloudy. What is the precipitate? Write
the reaction.

HOUSEHOLD CHEMISTRY 15

3. Hydrogen Sulphide. — Moisten a filter-paper with a solution
of acetate of lead and expose to the air until the end of the
lesson. Notice the black coloration due to the formation of lead
sulphide. This test works well in rooms where illuminating gas
is used.

4. Aqueous Vapor.— Saturate a strip of paper with cobalt chlo-
ride or iodide, thoroughly dry and expose to the air out and in
doors; under moist conditions, it turns pink.

Weigh a small watch-glass containing about I gram of fused
calcium chloride, wait about 2 hours and weigh again. Note the
increase in weight largely due to water.

5. Dew Point. — Take the temperature of the room, immerse
the thermometer bulb in a glass of water, and add ice little by
little until the first indication of moisture is seen on the outside
of the glass. If humidity is low, add salt to hasten process.
Note the thermometer reading; it is the dew point of the air in
the room.

6. Determination of Relative Humidity. — Use a sling or whirl
psychrometer. This instrument has two thermometers fastened
to a frame which can be whirled in the hand. The bulb of one
thermometer is covered with muslin which is made wet at the
beginning of the test. As the instrument is whirled evaporation
around this bulb reduces the recorded temperature until the dew
point is about reached, that is, the temperature at which no
further elimination of moisture takes place, but condensation
occurs. When the wet bulb thermometer registers its lowest
point the reading of both is taken and the dew point calculated.
(See Glaisher's table. Harrington: Practical Hygiene.)

7. Relation of Dust to Rain.— -Fit a 2-liter flask with a rubber
stopper having 2 perforations. Pass 2 pieces of glass tubing
through these, long enough to extend nearly half-way into the
body of the flask. Attach pieces of rubber tubing fitted with
pinch-cocks to the free ends of the glass tubing just above the
stopper. Put in the flask sufficient water to a little more than
fill the neck when the flask is closed and inverted. Keep the

1 6 HOUSEHOLD CHEMISTRY

flask inverted and allow the confined air to become saturated
with aqueous vapor. Now withdraw some of the air in the
flask by suction through one of the rubber tubes. The decreased
pressure causes a fall in temperature and a condensation of
moisture as haze or fine rain throughout the air space in the
flask. At this point introduce air through the rubber tubing to
restore the original pressure and the mist disappears. Now wash
the air in the flask with the contained water until its dust content
is removed. Repeat the experiment and note that no rain is
produced in the dust- free air.

8. Atmospheric Pressure.— Pour 2 inches of water into a clean
ordinary half-gallon can, boil vigorously and close the opening
with a close-fitting cork. Remove the burner and when cool the
can will collapse. The can should have a small opening and
preferably be rectangular in shape.

Ventilation.

The scope of this book prevents a detailed discussion
of ventilation and ventilatory systems. In fact it does
not seem possible at present to make definite statements
in regard to standards of temperature and composition
of air in a well-ventilated room, since the whole sub-
ject of ventilation is undergoing revision. Experts dis-
agree as to the comparative physiological effects of the
constituents of vitiated air, and if perfect systems of ven-
tilation have been devised, they are not in general use.
However, until all buildings are equipped with such a
system as a matter of course, a few facts and principles
should be generally known and brought to bear on the
ventilation of rooms under individual control.

Effect of Heat and Humidity. — It has been well estab-
lished that the main factors causing discomfort in poorly
ventilated rooms are excessive heat and humidity. With

HOUSEHOLD CHEMISTRY \J

increase in temperature, due perhaps to over-crowding,
the moisture in the air increases proportionately toward
saturation point. Evaporation from the body now be-
comes relatively impossible. But at a temperature of
70° F. or over, the body depends upon evaporation of
perspiration to maintain its heat equilibrium. The
danger now arises that the checking of evaporation may
cause the cutaneous blood vessels to become so congested
that the temperature of the skin is raised and heat trans-
fer by conduction and radiation is increased. This
occurs at the expense of the efficiency of the other organs,
particularly the brain. Headache, dizziness, and even
fever may result. Relief is at once felt in such cases
if evaporation is aided by setting in motion the air in the
room. If this cannot be done by bringing in free currents
of outside air, electric fans answer the purpose.

On the other hand, too rapid evaporation of water
from the skin and air passages will cause discomfort.
This is felt in the dry air of steam-heated rooms. The
skin becomes dry, the cutaneous nerves are irritated,
and the effect is felt by the central nervous system. This
trouble may be obviated by the evaporation of water
from a dish placed on the radiator.

The relation of heat and humidity to efficiency is
clearly pointed out in an article on Work and Weather?
by Dr. Ellsworth Huntington. The efficiency curves of
over 500 wage earners in Connecticut were studied dur-
ing a period of 4 successive years, and those of 1,600

1 Harper's Monthly Magazine, Jan., 1915.

l8 HOUSEHOLD CHEMISTRY

students at West Point and Annapolis for periods of
2 and 6 years respectively. The declination in amount
of work done is greatest at two periods of the year —
through January and a part of February, when windows
are kept closed and indoor conditions of temperature and
humidity are below standard and from the latter part
of June to the end of August. In the summer of 1911,
part of which was the hottest in 100 years in the locality
where the observations were made, the efficiency of the
operatives dropped astonishingly; in 1913, a cool sum-
mer, there was very little lowering of the curve.

Carbon Dioxide. — Contrary to former belief, carbon
dioxide in the largest quantities likely to occur in the
air of a room has little to do with the feeling of dis-
comfort. If the room is kept cool, the increase may be
up to 20, 30, or even 40 times the normal amount1 with-
out appreciable effect, and no serious physiological dis-
turbance results until the carbon dioxide content is raised
to about 3 per cent, with a corresponding lowering of
the oxygen. This is approximately 75 times the amount
present in pure air. At this point Dr. Angus Smith
found feebleness of circulation, slowing of heart action,
and quickened respiration, but could detect no inconven-
ience with 2 per cent. Pettenkofer and Voit experienced
no discomfort after long exposure to air containing I per
cent, of carbon dioxide.2

An adult will add 0.6 cubic foot of carbon dioxide to

1 Rideal : Report on Hygienic Value of Gas and Electric Light-
ing, presented before Royal Sanitary Institute, London, 1907.
s Education, London, Feb., 1912.

HOUSEHOLD CHEMISTRY 19

the air in I hour. Therefore in a room containing 3,000
cubic feet, the carbon dioxide will increase in that time
0.2 cubic foot per 1,000, or 0.2 part per 10,000, i.e.,
from an initial amount for pure air of 0.04 per cent.,
to 0.06 per cent., which is the limit of the standard of
purity generally given. Theoretically the air of such a
room with one occupant would require renewing each
hour, but fortunately the average room, not being air-
tight, is constantly receiving some outside air through
various openings.

"Crowd Poisoning." — Dr. Rideal states that the worst
|that can be said of even respiratory carbon dioxide is
that it is often found in bad company. Emanations
of a poisonous nature given off in breathing, cause the
unpleasant odors noticeable to a person coming into an
occupied room from the outside air. Disease germs are
likely to be present, and to circulate more freely if dust
is in the air. Moreover, sharp particles of dust may
have an irritating or lacerating effect on eyes, nose, or
lungs, making the tissues more susceptible to the entrance
of bacilli. Tuberculosis is commonly spread in this way.

Experiments made under the direction of C. E. A.
Winslow, chairman of the New York State Commission
on Ventilation (1914), show the effects of heat, humidity,
and stale air. It was found that when the temperature
of the room was raised from 68° to 75°, the pulse and
blood pressure were affected, and the amount of physical
work accomplished fell 15 per cent. None of these bad
effects was felt if the room was kept cool, although the

20 HOUSEHOLD CHEMISTRY

air was allowed to become stagnant for 8 hours, so that
the carbon dioxide content increased to about 20 times
the amount in pure air. A marked effect of this stale air
on the subjects was, however, loss of appetite, although
the odors accumulating in the room were not noticed by
them. This sub-conscious result was proved by serving
standard meals and calculating the amount eaten after a
period spent in fresh air and in stale air.

Methods of Ventilation. — Of the two methods of ven-
tilation— natural and mechanical — the former is the one
which must be depended upon in ordinary houses.
Natural ventilation relies upon the movement of air
currents caused by differences in temperature and grav-
ity, and the force of wind — an uncertain agent. It takes
into account the fact that air becomes lighter when
heated, and rises. Heated 50° F. above the outside air,
the air of a room will be increased one-tenth in bulk,
since it expands Vsoo of its volume for every degree
Fahrenheit. Consequently, since good ventilation re-
quires a constant supply of pure air and a corresponding
removal of foul air, there should be an inlet and an outlet,
the latter at the top of the room where the heated air
can escape, the former nearer the bottom, where the
colder air entering can have an opportunity of circulat-
ing through the room and pressing the warmer air up-
ward. The problem of ventilation in winter often be-
comes a question of draughts. If the inlet is arranged
so that the air may pass in a vertical direction over the
heads of the occupants of the room, and at the same

HOUSEHOLD CHEMISTRY 21

time be somewhat warmed, this trouble is remedied. If
the opened window is the only form of inlet possible, a
direct draught can be prevented by placing a frame in
the opening covered with some open mesh material such
as cheesecloth.

The inlets and outlets should be as far as possible
from each other, so that air will not pass directly from
one to the other without circulating. An outlet should
properly have the motive power of heat or an exhaust,
otherwise it may become an inlet for cold air. The wind
acts uncertainly as an exhaust at times; a mechanical
arrangement is more dependable. A fireplace is a de-
sirable natural outlet, having the extra motive power of
heat.

Heating by hot air is favorable to a good scheme of
ventilation, provided (i) that a steady supply of pure
air from outside is brought in to be heated and circulated
through the flues; (2) that an outlet for foul air be
provided in the room.

Stoves, steam and hot water heating systems offer little
aid to ventilation. On the contrary, stoves withdraw
the purer air near the floor for purposes of combustion.
Careful attention to ventilation is necessary with these
methods of heating.

Too often people live in tightly shut rooms in winter
because they cannot afford loss of heat by ventilating
openings. The injury to health is apparent in even a few
weeks, in lessened vitality, susceptibility to colds, and
actual disease. In such cases occasional throwing open

22 HOUSEHOLD CHEMISTRY

of windows with rapid exercise at the time answers the
purpose with less loss of heat. If one can become accus-
tomed to free circulation without draughts, the body tone
is raised so that less heat is required and the chances of
injury on exposure are lessened.

CHAPTER III.

WATER.

Water, or hydrogen monoxide, the universal solvent,
was believed to be an element until the experimental work
of Cavendish showed it to be the product of the chemical
union of hydrogen and oxygen. The proportions in
which these gases combine are two parts of H to one of

0 by volume, and one to eight by weight.

Physical Properties. — Latent Heat. — Water exists in
three states without change of composition: as a gas
(steam) at 100° j1 as a liquid (water) between o° and
100°, and as a solid (ice) below o°. In passing from
the solid to the liquid state, additional energy is required
for increased molecular spacing and motion. This is
obtained in the form of heat from surrounding objects,
and becomes the latent heat of fusion. The amount of
heat transformed in this way in melting I gram of
ice is sufficient to raise the temperature of I gram of
water from o° to 80°, or 80 calories (0.317 B. t. u.)
Conversely, when water freezes, 80 calories per gram are
released and appear as sensible heat.2

Steam being a gas, requires more energy for molecular

1 Unless otherwise stated, the centigrade scale is used in giving
thermometer readings.

2 Two calorie units are in use. The greater Calorie is the
amount of heat required to raise I kg. of water i° C. The lesser
calorie, the heat required to raise I gm. of water i° C. I Cal-
orie = i,ooo calories. The British thermal unit (B. t. u.) is
the quantity of heat required to raise I pound of water i° F.

1 Calorie is about equal to 4 B. t. u. as follows : I kilogram =
2.2 pounds, i° C. = 1.8° F. ; therefore I Calorie = 2.2 X 1.8 =
3.96 B. t. u. ; i calorie = 0.00396 B. t. u.

24 HOUSEHOLD CHEMISTRY

spacing and motion. To change I gram of water at 100°
to steam at 100° necessitates approximately 537 (536.6)
calories. One gram of steam, therefore, contains 537
calories plus the 100 calories of the boiling water. When
steam at 100° condenses to water at 100° 537 calories or
2.13 B. t. u. are given up as heat. One pound of steam
yields about 243,000 cal. or 966 B. t. u.

Specific Heat. — The capacity of water for heat is so
great that it is taken as the standard. The specific heat
of water is expressed as i ; that of most other substances
in fractions. For instance, the specific heat of alumin-
ium is 0.21, which means that the amount of heat which
will raise I gram of aluminium i° will raise i gram of
water 0.21°.

Conductivity. — Pure water is a poor conductor of heat
and electricity, but dissolved matter increases its conduct-
ive capacity.

Boiling and Freezing Points. — The boiling and freez-
ing points of pure water under standard atmospheric
conditions are used as convenient points for standard-
izing thermometer scales; in the Centigrade o°-ioo°; in
the Fahrenheit 32°-2i2°; in the Reaumur o°-8o°. An
increase in atmospheric pressure raises the boiling point,
a decrease lowers it. Boiling and freezing points are
also affected by substances in solution. Solutions having
increased density boil at a higher temperature and freeze
at a lower than pure water. If electrolytes are in solu-
tion the increase and decrease are greater than in the
case of non-electrolytes. For example, the boiling and

HOUSEHOLD CHEMISTRY 25

freezing points of a solution of sodium chloride are
higher and lower respectively than those of an equivalent
solution of sugar.1

Density. — The weight of i cc. of water at its point of
greatest density, 4°, is i gram. This is taken as the
standard of density, and is used as the unit in specific
gravity measurements of liquids and solids. The so-
called Baume hydrometer, an instrument used for deter-
mining the specific gravity of liquids, is made in two
types — for light and heavy liquids. The zero mark in-
dicates the floatation in distilled water at 60° F. for
heavy liquids, and in a 10 per cent, salt solution for light
liquids. To convert into actual specific gravity see
page 234.

Compressibility and Expansion. — Water in the liquid
state is practically incompressible. It is calculated that
the small compressibility of water causes a lowering of
the surface of the ocean to the extent of 600 feet where
the depth is 6 miles, or an average depression for the
large ocean bodies of 116 feet. On passing toward the
solid state, water contracts until it reaches 4°, its point
of greatest density. Below this point its volume in-
creases, and at freezing point, o°, there is a sudden
further expansion of 10 per cent. Consequently water
at 4° is heavier than at o°, a provision of nature which
makes it impossible for large bodies of water to freeze
solid. When water is converted into steam it expands
more than most other known liquids. The expression

1 100 parts of powdered ice at -ni° mixed with 30 parts of salt
give a temperature of — 22.4°.

26 HOUSEHOLD CHEMISTRY

"a cubic inch of water makes a cubic foot of steam" is
approximately true.

Chemical Properties. — As a chemical agent, water is
extremely potent. It acts usually as a solvent, but in
many cases produces profound chemical changes.
Briefly, the action of water may be classed as follows :
Water of Solution
Water of Hydration
Water of Hydrolysis.

Water of Solution. — When any solid dissolves in water,
loss or gain of heat is apparent, but on evaporating the
liquid the solid reappears in the original form. With
acids, bases and salts there is electrolytic dissociation in
addition to solution.

Water of Hydration. — On partial evaporation of the
liquid, the soluble substance reappears in changed form,
containing a definite amount of the water in the solid
state. This is known as water of hydration or crystal-
lization. Familiar examples are washing soda, Na2CO3,
ioH2O; alum, K2A12(SO4)4, 24H2O; borax, Na2B4O7,
ioH2O; Glauber's salt, Na2SO4, 5H2O, and copper sul-
phate, CuSO4, 5H2O.

Water of Hydrolysis. — Complete hydrolysis is a change
in which water enters a substance as H and the hydroxyl
OH, splitting it into new compounds generally simpler
than the original substance. The changes which food
undergoes in the processes of digestion are examples of
hydrolysis, such as the breaking down of sucrose into
fructose and glucose :

C.AA, + H,O -~ 20.^,0..

HOUSEHOLD CHEMISTRY 2.J

The solution of the non-metallic oxides SO3, N2O5 and
P2O5 is another example :

SO, + H20 — S02(HO)2 or H3SO,.
N205 + H,O~ 2NO2HO or 2HNO3.
PA + 3H20~ 2PO(HO)3 or 2H3PO4

or the solution of caustic alkalies and slaking lime :
Na2O + H2O — 2NaOH.
CaO + H20~Ca(OH)2.

Applications. — Explain the principle of the ice box, the
fireless cooker, the double boiler, the vacuum pan, the
digester kettle, the unglazed water jar, the freezing mix-
ture of ice and salt.

Why are cranberry bogs flooded in winter, or tubs of
water put in vegetable cellars or under orange trees on
frosty nights ?

Explain the effectiveness of steam heating, hot water
heating, a hot water bag.

Why is salt put on an icy sidewalk in winter ?

Why is a scald from a steam burn worse than one
from boiling water ?

Why does water boil more quickly when there is con-
siderable water vapor in the atmosphere ?

How does adding salt to the water in boiling vege-
tables and keeping the cover on the dish affect the boiling
point ?

Why is a mixture of ice and salt more effective than
ice and sugar in freezing ice cream ?

Explain the cooling effect of perspiration.
3

28 HOUSEHOLD CHEMISTRY

EXPERIMENTS ON WATER.

1. Heat Conductivity.— Fill an 8-inch test tube two-thirds full
of water, grasp the lower end of the tube with the fingers and
hold in the flame at a slight inclination from the perpendicular.
Note that the upper part will boil before the lower becomes
uncomfortably hot to hold. Reverse the order of heating and
note the same result. Explain.

2. Boiling Point Under Atmospheric Pressure. — Pour about
250 cc. of distilled water into a half-liter round bottom flask
supported on a ring stand. Introduce a thermometer so that the
bulb only is immersed in the liquid and apply heat. Note the
point to which the mercury rises when the liquid is quietly boil-
ing, raise the thermometer bulb just out of the liquid and take
the reading. Is there any difference? Does the thermometer
indicate any higher degree of heat when the liquid boils
violently ?

3. Boiling Point Under Reduced Pressure. — Select a cork which
fits the flask closely, pierce a hole through it and insert a ther-
mometer. Fill the flask one-third full with water and boil the
liquid. When in active ebullition, close the flask with the cork
and thermometer and instantly withdraw the heat. When the
liquid ceases to boil, read the thermometer, and grasping the
neck of the flask with several folds of a towel, hold it under
running cold water. What happens? Read the thermometer
and explain.

4. Convection. — Water may be made to show the path of travel
of convection currents as follows :

Fill a 500 cc. beaker two-thirds full of distilled water, place
over wire gauze on a ring stand and apply heat by placing the
Bunsen burner on one side of the bottom. When the water is
warm drop into it a few crystals of fuchsin or other soluble
coloring matter and watch the path of the crystals through the
water.

5 Influence of Soluble Matter. — Note the boiling point of a
solution of 10 grams of salt in 100 cc. of distilled water. Ob-

HOUSEHOLD CHEMISTRY 29

serving the same conditions throughout, repeat the experiment,
using sugar. How do the boiling points compare? Explain.
Cool each solution to 15° and take its specific gravity.

6. Take the specific gravity of a mixture of equal volumes of
water and 95 per cent, alcohol, and note its boiling point.
Explain.

7. Weigh out 30 grams of table salt, measure 100 cc. of dis-
tilled water, and use only as much of the water as is required
to make a saturated salt solution (pickle). What is the required
proportion of salt to water? Take the specific gravity of the
solution and its boiling point, and compare with Experiment 5.
Will a fresh egg float or sink in this liquid? Evaporate a few
drops of the solution on a microscope slide and observe the salt
crystals under a low power lens.

8. Hydration and Hydrolysis.— Take a tablespoonful of com-
mon plaster, mix this with half the volume of water in a porce-
lain dish, stirring with a thermometer. Record the result and
explain.

9. Slowly pour about 10 cc. of strong sulphuric acid into 50 cc.
of cold water, stir well with a thermometer, and from time to
time record the temperature. Explain.

10. Using a burette, carefully mix exactly 52 volumes of alco-
hol (95 per cent.) and 48 volumes of water in a 100 cc. stop-
pered cylinder. How many volumes result? Explain.

11. Add half a teaspoonful of dry pulverized lime (CaO) to
an equal volume of cold water, stir the mixture with a ther-
mometer, adding more water if necessary, and record the ther-
mometer reading. Explain and write reaction.

Potable or Drinking Water.

Classification of Natural Waters. — Natural waters are
never pure, as they dissolve or hold in suspension gases,
liquids, and solids with which they come in contact. The
following is a convenient classification :

HOUSEHOLD CHEMISTRY

Natural
Waters

f Rain

Atmospheric ] Snow
I Fog

Terrestrial

Sweet

Salt

— Contains very little dis-
solved solids but dust
and gases of the atmos-
phere.

Surface — Cloudy, usually a
large amount of suspended
matter, minimum of dis-
solved.

Underground — Clear, m i n i-
mum of suspended matter,
maximum of dissolved.

J Brines — over 5% soluble salts.
1 Sea water — 3.6% solids.

Mineral — excess of, or unusual
mineral matter and gases.

Potable or drinking water should be clear, free from
odor and color, and should not contain in excess of 20
grains of solids per U. S. gallon, of which not more than
one-half is organic matter.

The soluble mineral matter in water consists of a mix-
ture of the following salts :

Carbonates Sodium

Bicarbonates .. Potassium
Sulphates Calcium

Chlorides Magnesium

together with oxide of iron and silica in minute amounts.
An excess of chlorides may be due to sewage or animal
contamination, excess of lime causes hardness, and excess
of iron usually is apparent from the color and is probably
due to the solvent effect of organic matter in the water.
On boiling, water loses its dissolved gases, hence dis-
tilled or sterilized water is flat or stale.

Qualitative Examination of Water. — The importance of
guarding a water supply from contamination is evident.

HOUSEHOLD CHEMISTRY 31

Equally important are frequent expert analyses of the
supply in order to be sure that the safeguards used are
effective. No attempt will be made in this book to give
methods for the quantitative estimation of the impurities
found in water. However, certain qualitative tests are
suggested which will aid in detecting such impurities when
present in abnormal amounts ; it is only when found in
such amounts that the water is open to suspicion. The
impurities are for the most part harmless in themselves,
but if found demand quantitative analysis and possibly
bacteriological examination. A thorough investigation
of the surroundings and of the sources of contamination
of the supply, and great care in taking the sample, are
essential in making an examination of any water.

The tests usually made are with regard to color and
appearance, odor and taste, and for the presence of total
solids, free and albuminoid ammonia, nitrogen as nitrites
and nitrates, chlorine, temporary and permanent hard-
ness and sometimes phosphates, sulphates, etc.

The color and turbidity, odor and taste of a drinking
water are not in themselves indications of its purity, but
taken with other data, help in forming an opinion of the
sample. A clear, colorless, tasteless water may be pol-
luted ; on the other hand a safe water may have acquired
color from dissolved iron, a "peaty" taste from swamp
vegetation, or a fishy odor from the decay of algae.

Odor. — Rinse a stoppered flask with the water to be tested,
fill it two-thirds full of the sample, cork, shake violently, remove
the stopper and note the character and intensity of the odor.
Replace the cork, warm the water over a water bath to 40°,
remove, again shake thoroughly and observe the odor as before.

32 HOUSEHOLD CHEMISTRY

The odor will be strengthened by heating. A putrid or offensive
smell probably indicates sewage contamination.

Color and Turbidity.— Fill one of two Nessler's tubes with the
water under test, the other with an equal volume of distilled
water. Compare the color and clearness of the two by observing
against white paper.

Total Solids. — This is a method of determining the
total residue left by the water on evaporation, and the
proportion of mineral and organic matter present. The
following experiment gives an approximate estimation1
of total solids :

1. Weigh a clean porcelain dish, measure into it 100 cc.2 of
the water to be tested, and evaporate to dryness over a water
bath. Cool and weigh. The increase in weight gives total solids.
Apply gentle heat and notice any charring (due to organic
matter). A sour odor at this point indicates sewage contamina-
tion ; a peaty odor, the presence of swamp water. Continue heat-
ing until the residue is white or nearly so ; cool and weigh. The
loss in weight represents organic matter and CO2 due to bicar-
bonates; the residue is mineral matter. Some inaccuracy must
be expected, due to the action of heat in volatilizing alkali
chlorides.

2. Concentrate 100 cc. of the water to about 10 cc., cool and
test for mineral matter as follows :

(a) Phosphates. A few drops of the liquid, acidified with
HNO3, is added to a larger quantity of ammonium molybdate
and heated in boiling water. A yellow crystalline precipitate,
ammonium phosphomolybdate, indicates phosphates. Phosphates
are seldom found in drinking water. If present they indicate
probable sewage contamination.

1 For exact methods, see Air, Water and Food, Richards and
Woodman, and Hxamination of Water for Sanitary and Tech-
nical Purposes, Leffmann and Beam.

2 If 100 cc. are evaporated, the residue in milligrams represents
so many parts per 100,000; if 58 cc. are taken, each milligram
of residue is equivalent to a grain per U. S. gallon.

HOUSEHOLD CHEMISTRY 33

(b) Chlorides. Add a drop of HNO3, then AgNO3. A white
precipitate of silver chloride, AgCl, soluble in NH4OH, indicates
chlorides.

(c) Sulphates. Make faintly acid with HC1 and add a few
drops of BaCk A white crystalline precipitate, BaSCX, insoluble
in HC1 indicates soluble sulphates.

(d) Carbonates. To 40 or 50 cc. of clear lime water add a
small amount of the original sample. Any cloudiness soluble in
acetic acid indicates carbonates. Make the flame test on the con-
centrated water. A yellow color indicates sodium; a violet,
potassium. View the latter through blue glass.

(e) Iron as ferric compounds. Slightly acidify with HC1 and
add NHUSCN. A blood red color, Fe2(SCN)<, indicates iron.
Or, to determine the oxidation of the iron, to the acidified water
add K4Fe(CN)6. A dark blue color indicates ferric salts. With
K3Fe(CN)fl a blue color indicates ferrous compounds.

(/) Calcium. Add NH4C1, NH4OH, and (NH4)2C2O4. A
white crystalline precipitate of calcium oxalate, CaC2O4, soluble
in HC1, forms on boiling. If calcium is present, filter, and save
the filtrate for (g).

(g) Magnesium. To the above well cooled filtrate add sodium
phosphate and shake vigorously. After standing, magnesium
shows as a white crystalline precipitate of ammonium magnesium
phosphate, NH4MgPO4.

(/») Aluminium. Add NH4C1 and an excess of NH4OH.
Warm the solution. A white flocculent precipitate of aluminium
hydroxide, A1(OH)3, appears on standing, if considerable alum
is present. The logwood test (p. 174) is more delicate for small
amounts.

(0 Manganese. Prepare a Na2CO3 bead on platinum wire.
Cool and dip in original solution. Reheat in the oxidizing flame.
A bluish green color on cooling indicates manganese.

Free and Albuminoid Ammonia. — Two forms of am-
monia are looked for in water — free and albuminoid.
Neither of these is injurious in itself, but their signifi-

34 HOUSEHOLD CHEMISTRY

cance lies in the fact that they indicate conditions favor-
able for pathogenic bacteria. The free or ureal ammonia,
if present in any quantity, is considered to show recent
sewage pollution, as, although it is found in rain water,
and may be formed by the decay of certain algae, it is
directly associated with animal excretions, e. g., urea.
Urea readily yields free ammonia as follows :

(NH2)2CO + 2H20 — (NH4)2C03.
(NH4),COS •— 2NH3 + H2O -f CO2.
Since ammonium carbonate decomposes as above on
heating, it is evident that free ammonia can be obtained
by simply boiling the water.

Albuminoid ammonia will not volatilize by this treat-
ment. When present, it indicates undecomposed organic
nitrogen, generally as low forms of plant life. It is
necessary to oxidize these substances to volatile com-
pounds before this form of ammonia can be obtained by
distillation.

Determination of Free and Albuminoid Ammonia. —
The method to be followed is distillation, successive dis-
tillates to be obtained and tested with Nessler's solution,
which gives a yellow or brown color in the presence of
ammonia.

Directions. — Thoroughly cleanse and rinse with distilled water
a round bottom half-liter flask and a number of 6-inch test
tubes. Connect the flask with either a condenser or a long piece
of glass tubing arranged to deliver into the receiving test tubes,
which in this case must be cooled by running water or ice. Make
all connections tight. Fill the flask about two-thirds full of the
water to be tested, add 5-10 cc. of Na2CO3 solution and distil
with moderate heat. Collect the distillates in equal amounts,

HOUSEHOLD CHEMISTRY 35

about 15 cc., in successive test tubes, and add to each the same
number of drops of Nessler's solution. Observe any deepening
of color by looking down through the tube against a white back-
ground. The color may be compared with standard ammonia
solutions. Continue the distillation until a sample shows no
color with Nessler's. Save the distillates for comparison with
the yield of albuminoid ammonia in the following:

Cool the balance of the water in the flask and add alkaline
potassium permanganate in the proportion of about 5 cc. to
200 cc. of water. Distil with steady moderate heat, collect and
test successive distillates as before. The alkaline permanganate
solution oxidizes the nitrogen in the form of albuminoid ammo-
nia to compounds yielding free ammonia.

Nitrites and Nitrates. — The presence of nitrites in
water is supposed to be due either to the incomplete
nitrification of ammonia or to the reduction by micro-
organisms of nitrates already formed. While traces of
both may occur in all natural water, a large quantity
suggests previous pollution by nitrogenous organic mat-
ter of animal origin. This material begins the nitrogen
cycle; by decomposition and the work of micro-organ-
isms ammonia compounds follow, and these in turn are
oxidized by aerobic organisms to nitrites. Further oxi-
dation by another group of organisms converts these into
nitrates. If now nitrates come within reach of
chlorophyll bearing plants, they complete the cycle by
converting the oxidized nitrogen back to organic nitrogen
again. The importance of nitrite and nitrate determina-
tion in studying a water supply is evident.

In one of three 6-inch test tubes put 20 cc. of nitrite-free
water (use distilled), in another the same amount of the water
under test, in the third nitrite water (to be furnished by the

36 HOUSEHOLD CHEMISTRY

instructor). To each add I cc. of a freshly prepared mixture
of equal parts of sulphanilic acid dissolved in acetic acid, and
naphthylamine acetate dissolved in dilute acetic acid. Mix and
allow to stand 30 minutes. If the solution becomes pink the
water contains nitrites.

Chlorides. — Chlorine is found mostly as sodium
chloride, although other chlorides may be present. The
amount of sodium chloride in any given water supply is
affected by the character of the soil, proximity to the
ocean, etc., but it should be constant for the locality.
Any marked increase over the normal figure indicates
sewage contamination.

Place in a small casserole or porcelain dish about 100 cc. of
the water to be tested, and in another dish the same amount, of
distilled water. Add to each 2 or 3 drops of potassium chromate
solution, then add drop by drop a dilute solution of silver nitrate
(N/io), stirring after each drop until a faint tinge of red
remains. Obtain the same tint in each, and note the number of
drops of silver nitrate used in each case. Each drop of silver
nitrate solution is equivalent to 0.000293 gram sodium chloride.

Oxygen Consuming Power. — This is a method of esti-
mating the organic matter in water by its decolorizing
power in the presence of potassium permanganate. The
test is not especially significant even when performed
quantitatively, as it is not delicate or definite.

Fill two clean 6-inch test tubes, one with the water to be tested,
the other with distilled water, and add to each the same amount
of acidified potassium permanganate solution. Be careful not to
obtain too deep a tint and see that the shades match. On stand-
ing 10 minutes, there should be an appreciable lightening in color,
greatest in the tube of water under test. If the color entirely
disappears, the amount of organic matter is probably dangerously
great. Compare with the test under total solids.

HOUSEHOLD CHEMISTRY 37

Ice used in drinking water should be examined as to
purity. A sample may be melted and tested by the
method described for water.

Water Purification.

Household Methods.1 — Boiling. — Boiling is the simplest
and most effective household method of making a drink-
ing water safe, as typhoid and other pathogenic bacteria
are killed. Boiled water has a flat taste due to the loss
of dissolved gases, but this can be remedied by aeration.

Effect of Charcoal. — Charcoal is useful as a decolor-
izer and deodorizer.

To 50 cc. of water add enough vinegar to give it a distinct but
not deep yellow color, then divide into two equal parts. Filter
one through dry freshly ignited boneblack several times and com-
pare the color of the resulting liquid with the original solution.

Effect of Alum. — Alum readily ionizes in water, form-
ing a flocculent precipitate of aluminium hydroxide,
which collects any suspended matter and removes it by
sedimentation. It is thus useful in clearing turbid water
for laundry purposes, swimming pools, etc., and is used
on a large scale in some nitration beds.

Take any sample of cloudy or slightly colored water, even
soapy water will answer. Add a very small quantity of finely
powdered alum, shake well, filter, and compare with the original
sample. Write the reaction for the formation of aluminium
hydroxide.

Water should be neutral or slightly alkaline to work
well with alum.

1 For public methods of water purification, see Food Industries,
Vulte and Vanderbilt, and Our Water Supply, Mason.

38 HOUSEHOLD CHEMISTRY

Filtration. — Prove by the following experiment the
effect ordinary filtration has upon substances in solution
or suspension in drinking water :

Filter a dilute salt solution; taste the liquid. Is any change
produced? Add to the filtrate a few drops of AgNO3, shake
well and filter again. Note any difference.

Household filters of the Berkefeld, Pasteur-Chamber-
land and Aqua Pura types are effective, as they remove
micro-organisms as well as suspended matter.

Distillation. — This is an effective method of purifying
water, but not so simple for household practice as boiling.
From the following experiment the student is expected
to determine the effect of distillation with reference to
volatile and non- volatile substances :

Using the same apparatus as for the determination of ammo-
nia, distil with moderate heat a solution of about 2 grams of
copper sulphate in 250 cc. of water. Is this solution acid? Care-
fully examine the distillate for copper sulphate. Remove the
burner, cool the apparatus, and add 5 cc. of ammonia, shaking
well; a deep blue color should be obtained. Distil this liquid
and test the distillate as before. Explain.

Hard and Soft Water.

With reference to its detergent action, two kinds of
water are recognized — hard and soft. Hard waters con-
tain calcium and magnesium salts which are undesirable
in many industries. They produce the troublesome
boiler scale, they are a serious objection in sugar refin-
ing, and in many textile operations, especially in dyeing.
In the household hard water makes a poor detergent,
because soluble calcium and magnesium salts form in-
soluble compounds with soap, which not only have no

HOUSEHOLD CHEMISTRY 39

cleansing value, but produce a troublesome curd. A
certain amount of soap must be lost in this way before
a lather will form and cleansing begin. The degree of
hardness a water possesses may be measured by its soap-
destroying power. The total hardness of most water is
of two kinds — temporary and permanent.

Temporary Hardness. — This form is caused by carbon-
ates of calcium and magnesium held in solution as bi-
carbonates by carbon dioxide present in the water. Boil-
ing expels the CO2, causing a precipitation of calcium
and magnesium carbonates, and the temporary hardness
is removed. Calcium hydroxide is often used on a large
scale for the same purpose. Its effect can be shown as
follows :

Ca(OH)2 + Ca(HCO3)2 •— 2CaCO3 + 2H2O.
Pass a current of CO2 gas into a small amount of lime water
until the precipitate clears. What was the precipitate? What
does the water now contain? Write the reactions. What hap-
pens if more lime water is added? Write the reaction, and show
that for every nine parts of hardness four parts of Ca(OH)»
are required.

Permanent Hardness. — Permanent hardness is due to
the presence of calcium sulphate and other soluble salts
of calcium and magnesium, not carbonates, held in solu-
tion by the solvent action of the water itself. Such a
water cannot be affected by boiling, but may be softened
as follows :

1. Prepare a hard water by dissolving o.i gram of calcium
sulphate in 500 cc. of distilled water. Add sodium carbonate
solution to a portion, and note the result. Write the reaction.
Filter and save the nitrate.

2. Roughly determine the amount of soap solution necessary

40 HOUSEHOLD CHEMISTRY

to make a lather lasting 5 minutes in (a) 50 cc. of the above
filtrate, and (fr) an equal amount of the untreated hard water.
What is the effect of the Na2CO3?

Quantitative Estimation. — To estimate the total hard-
ness of a given water the procedure may be as follows :

Make a standard soap solution by dissolving 10 grams of good
castile soap in sufficient 90 per cent, ethyl alcohol to make up to
i liter. For use mix 100 cc. of this soap solution with 100 cc.
of distilled water and 30 cc. of 95 per cent, alcohol.

Put 58 cc. of the water under test in a clean stoppered 8-ounce
bottle, add the soap solution y2 cc. at a time, shaking thoroughly
after each addition. Continue until a lather is formed which
will cover the surface of the liquid when the bottle is placed on
its side, and will last 5 minutes. Note the amount of soap solu-
tion used.

Estimate the total hardness of the water in grains per
gallon by using the following data :

One U. S. gallon contains 58,318 grains, 58 cc. contains
58,000 milligrams. Therefore, 58 cc. represents a minia-
ture U. S. gallon, and I milligram per 58 cc. stands
for i grain per gallon, approximately. One cc. of the
standard soap solution is the equivalent of i milligram
of Ca, calculated as CaCO3.

For example, if 10 cc. of soap solution are used, a
gallon of the sample contains 10 grains of Ca, spoken of
as 10° of hardness. This will be the total hardness of
the water.

To estimate the temporary hardness, boil 58 cc. of the sample
for I or 2 minutes, cool to the temperature of the unboiled water,
and make up with distilled water the loss by evaporation. Add
the soap solution as before and note the amount required, now
that the temporary hardness has been removed. In this case
the permanent hardness has been overcome by the soap solution,

HOUSEHOLD CHEMISTRY 41

and the difference in the amounts of the soap solution used in
the two cases is the measure of the temporary hardness of the
water.

Use of Washing Soda. — Washing soda is cheaper and
more efficient than soap in softening hard water. The
following equations show the ratio of efficiency between
the two :

(1) CaSO4 + Na2CO3 — > CaCO3 -f Na2SO4.

136 106 ' , •

(2) CaSO4 + 2C17H35COONa •—

(C17H35COO)2Ca + Na2S04.

Therefore 612 pounds of pure soap are required to do
the work which 106 pounds of washing soda will do,
making a ratio of 6:1. But since much yellow laundry
soap is only about one- third actual soap, the balance
being resin, water, and other substances, the ratio be-
comes 18:1, and in actual practice I pound of washing
soda is considered equivalent to 18 or 20 pounds of soap.
A white laundry soap of good quality averages about 75
to 85 per cent, actual soap.

Problem. — A water contains 15 grains (approximately
i gram) of Ca per gallon. How much of Na2CO3, white
soap, and yellow laundry soap will be required to over-
come the total hardness1 of 500 gallons ? Assume that
the 15 grains of calcium are in the form of calcium sul-
phate.

Natural soft waters are usually recommended for the
laundry, solely because they are lacking in soluble lime

1 For exact methods of hardness determination, see Hehner's
alkalimetric method in Examination of Water by Leffmann and
Beam.

42 HOUSEHOLD CHEMISTRY

and magnesia compounds which would waste soap. But
organic matter present in this class of water, through
stagnation or from soil rich in humus, dissolves notable
quantities of metallic oxides from containers and con-
duits, so that water of this class may become hard from
the presence of soluble organic salts of such elements as
iron, lead, copper, tin, zinc, etc. In the usual hot water
supply of the household this is noticeably the case. So
that a moderately hard water — temporary hardness best
for the cold supply — which will deposit insoluble lime
compounds on the exposed metallic surfaces, is a safe-
guard. Probably the ferrous compounds of iron are the
worst to deal with, as they usually are not noticeable
from lack of strong color, but readily show in the oxi-
dized form as iron rust spots after drying and ironing
white garments. If iron is present it should be com-
pletely removed, either by long boiling and settling or
filtering, or by adding washing soda, borax, or ammonia,
then boiling and settling. Organic matter may be dis-
closed by the permanganate test. If present in consider-
able quantity it would be well to oxidize both the fer-
rous compounds and the organic matter by means of
additional permanganate and heat, finally settling or fil-
tering, to remove any residue.

CHAPTER IV.

METALS.

The aim of this chapter is the study of the physical
and chemical properties of metals, rather than of their
compounds, especially with regard to their use in the
household. Therefore only those in common use will
be considered. Such metals are iron in its various forms,
nickel, zinc, copper, aluminium, silver, lead, tin and cer-
tain alloys.

Iron, (Ferrum) Fe, occurs in nature largely in the
form of oxides: haematite, Fe2O3 (red), and magnetite,
Fe3O4 (black), the latter possessing magnetic qualities
and commonly called lodestone.

The metal is obtained by fusing the ore in shaft fur-
naces with excess of carbon and enough limestone to
furnish a fusible ash or slag with the silicious matter
present in the ore. The following equations explain the
reduction and slagging:

2Fe,04 + SCO — 3Fe2 + SCO,.

SiO2 + CaO — CaSiO3.

The product, "pig iron," or crude cast iron, contains
from 3-4 per cent, of carbon as graphite and combined
carbon or carbide of iron, Fe3C, rendering the mass
fusible. By careful smelting in small shaft furnaces
called "cupolas," the pig iron is obtained in the form of
gray, white and mottled iron, depending on the rapidity
of cooling the moulds. Pig iron frequently contains
small amounts of impurities, sulphur and phosphorus,
4

44 HOUSEHOLD CHEMISTRY

rendering the product short or brittle, while hot or cold ;
during the refining process these are almost entirely
removed in the slag.

Cast iron is brittle and hard, it melts without soften-
ing at 1,200° and yields a thin liquid which may be cast
in sand moulds. The quality of the product depends
largely on the purity of the iron (freedom from S. and
P.), its temperature of cooling, and the smoothness of
the mould.

Cast iron heats more slowly but retains its heat better
than other forms of the metal, hence its use for oven
plates, sad-irons, stove lids, etc. If heated repeatedly to
redness in presence of air and quickly cooled its carbide
content increases at the expense of the graphite, and it
becomes whiter and more brittle. This causes the fre-
quent cracking of old stove lids. Slow cooling allows
less carbide to form ; as a result the lid is less brittle, less
liable to crack, and has a darker appearance. On the
other hand, the hardness of carbide is desirable in sad-
irons, accordingly they are frequently heated to a high
temperature and plunged into cold water. Cast iron can
be made harder than steel, and is sometimes used for the
wheel in glass cutters. It does not oxidize as readily as
steel or wrought iron.

Malleable iron is intermediate between cast and
wrought iron. It is made by slowly cooling cast iron to
increase its graphite content and elasticity. It is there-
fore softer and less brittle than ordinary cast iron, and
is much used in house hardware.

HOUSEHOLD CHEMISTRY 45

Wrought iron and steel are prepared from pig iron
by burning out part of the carbon in hot air furnaces of
special construction. The reverberatory furnace for
producing wrought iron is really a large oven heated by
gas and provided with a powerful blast of hot air.
Liquid pig iron is run on to the hot furnace bed where
the excess of oxygen removes the carbon as follows:
C2 + O2 -~* 2CO. As the CO escapes from the liquid
mass it produces a bubbling like any boiling liquid.
Gradually as the carbon is burned out, the iron becomes
pasty or semi-solid and is collected in balls with large
pokers operated by hand (puddling). When the balls
are of sufficient size they are removed with tongs,
squeezed to remove slag and rolled into short bars
(blooms or billets). The blooms are then reheated until
soft and rolled in bars and rods ; when cold the bars may
be drawn down through steel dies into wire of almost
any degree of fineness. They are cold forged into nails
and tacks. Piano wire, the purest form of iron, con-
tains 99.7 per cent. Fe, the balance is mainly carbon.
Cold wrought iron is quite soft, bends easily and has
great tensile strength. It does not melt readily (1,600°)
but softens on heating and may be forged and welded.

Steel is a form of iron between cast and wrought,
containing 1.5 per cent, carbon. When heated and slowly
cooled it is soft (mild), but if suddenly cooled is harder
than glass. Hardened steel cautiously reheated, may be
softened to any desired extent (tempering). At a high
temperature steel melts and may be cast like iron.

Two kinds of steel are manufactured, i. e., Bessemer,

46 HOUSEHOLD CHEMISTRY

the cheaper variety used for rails, plate for making so-
called sheet tin and galvanized iron, wire nails, etc.,
and open hearth steel, a more expensive variety used for
cutlery and tools.

Bessemer Process. — The cast iron is first melted in a
cupola, and then run into a special furnace (the con-
verter), where a powerful blast of hot air bubbles
through the molten liquid and quickly (15 minutes)
burns out the carbon and other impurities and even pro-
duces some oxide. Just at this point, a small portion of
molten cast iron containing manganese and the proper
amount of carbon is added and the mixture immediately
poured into the moulds and cooled. The function of the
manganese is to assist in holding the carbon in solution.

Open Hearth Method. — The cast iron is melted in a
gas furnace with dish-shaped bed together with scrap
wrought iron and iron ore. After 8 or 10 hours' heating,
the operation is complete and the liquid steel is drawn
off and cast in ingots.

Steel rusts much more readily than cast iron and
usually needs, especially if polished, a protecting coat
of oil. Rust may be removed from iron or steel by soak-
ing in kerosene and rubbing with fine emery' or carbor-
undum and oil, but stoves and sad-irons should not be
coated with kerosene and allowed to stand, as unsat-
urated compounds in the hydrocarbon take up oxygen
and cause the iron to rust.

Galvanized Iron. — See zinc.

Properties of Iron. — Iron has a specific gravity of 7.8,

HOUSEHOLD CHEMISTRY 47

and when pure fuses at about 1,800°. It is strongly at-
tracted by magnets. In moist air it oxidizes readily,
forming red oxide or common iron rust, Fe2O3. This
oxide is soft and friable and does not protect the metal
from further action. It is slightly soluble in water,
giving it a characteristic taste, experienced in drinking
water conducted by iron pipes. The other type of oxide,
Fe3O4, is formed by the oxidation of hot iron, or by the
action of superheated steam and carbon monoxide
(Barff Process). Fe3O4 forms a dark gray adherent but
brittle coat and protects the metal from further action.
It is called the magnetic oxide or blacksmith's scale.
Russia iron is sheet iron which has been given this lus-
trous protective oxide coat. It is used for stovepipes,
etc. The red oxide forms the basis of pigments such as
Venetian and Tuscan red.

Iron reacts readily with warm dilute acids, but resists
the action of alkalies.

EXPERIMENT.

Boil small pieces of bright and rusty iron in separate test
tubes in the following liquids: Dilute hydrochloric acid (i: i) ;
20 per cent, acetic acid, and 10 per cent, caustic soda solution.
Note comparative strength of action. Filter off the liquid in
each case, and test with ammonium thiocyanate in the presence
of hydrochloric acid. A blood red color shows iron in solution.
Record the results. Write reaction between FesCl<, and NJkSCN.

Nickel, a hard white metal, occurs in the pure state
only in meteorites, but is found combined in several
minerals. It is obtained by smelting in the blast fur-
nace. As it takes a high polish and is only slightly sus-

48 HOUSEHOLD CHEMISTRY

ceptible to oxidation in moist air, it is largely used as a
protective and decorative coating for iron and copper.
The method of plating nickel on iron is similar to silver
plating. The bath contains ammoniacal nickel sulphate,
(NH4)2SO4,NiSO4,6H2O, in which the article to be
plated is suspended, after having been cleaned by acid.
This forms the cathode, and a nickel plate the anode.

Nickel plated articles should always be cleaned with
a mixture of diluted ammonia and whiting, or rouge,
and polished with soft cotton waste.

Nickel has a specific gravity of 8.8, and a melting point
of i, 500°- 1, 600°. As an ingredient of alloys, nickel is
found in German silver (nickel i part, zinc I part, cop-
per 2, parts), and in coin nickel (copper 3 parts, nickel

i).

It is not active with dilute acids, and like iron resists
the action of alkalies.

EXPERIMENT.

Heat small pieces of pure nickel with dilute acids and alkalies
as under iron and record the results. Soluble salts of nickel
have a green color and yield a black precipitate, NiS, with
ammonium sulphide. Neutralize acid solutions with NH4OH
before adding (NH^zS. Write reaction between NiCU and

Pure nickel utensils are valuable in the household, but
the initial cost is comparatively high. In the laboratory
they form a desirable substitute for iron.

Zinc occurs chiefly as calamine or zinc blende, ZnCO3.
After calcination to drive off CO2, the oxide is mixed
with carbon and distilled in earthen retorts at 1,300-

HOUSEHOLD CHEMISTRY 49

1,400°; crude metallic zinc "spelter" condenses in the
receivers and CO burns at a small opening.

ZnCO3 — * ZnO + CO2.

2ZnO -f- C2 — * 2Zn + 2CO.

Zinc is bluish white, highly crystalline and brittle when
cold. By heating to 120-150° and rolling under hot rolls
it remains pliable and soft on cooling (sheet zinc). At
200-300° it becomes brittle again, melts at 433° and
boils at 920°. Its specific gravity is 7.

Zinc burns in the air with a bluish white flame, yield-
ing a white oxide which is the base of the pigment
Chinese white. Zinc oxide is a common ingredient of
face creams and other toilet preparations.

In moist air, it oxidizes and absorbs CO2, forming a
thin adherent coat of basic carbonate which protects the
metal from further change. Dilute acids readily dis-
solve this coating and thus restore the original brilliancy.
Acids and alkalies freely attack zinc, liberating hydrogen
and producing soluble compounds which are poisonous,
hence zinc vessels should never be used for the prepara-
tion or storage of food. Do not attempt to cleanse zinc
or galvanized iron with anything but neutral soap and
hot water.

Sheet zinc is frequently used for roofs, gutters, cor-
nices and leaders of buildings; but does not last well
near the seashore, on account of the salt in the atmos-
phere.

The molten metal mixes in all proportions with cop-
per, tin, and antimony. (See German silver, brass, etc.)

50 HOUSEHOLD CHEMISTRY

Zinc, both cast and rolled, is largely used in primary
batteries. It lasts much better if cleaned with dilute
sulphuric acid and coated with mercury (amalgamated).

EXPERIMENT.

In a dilute salt solution immerse bright strips of sheet copper
and zinc in metallic contact. Prove by examination of the liquid
which element suffers by the action. If zinc is in the solution,
potassium ferrocyanide will give a white flocculent precipitate
of zinc ferrocyanide in acid solution. Test for copper by adding
an excess of ammonium hydroxide; a blue color shows its
presence.

Galvanized iron is sheet iron or steel which after being
cleaned with acid is dipped in molten zinc. It is prac-
tically a zinc article, resists rust, and should not be used
as a receptacle for food.

Copper. — Copper (cuprum1), Cu, is found native, also
as sulphide and carbonate. Native copper ore is crushed,
washed to remove rock and melted with flux. The metal
usually contains a small amount of silver which is re-
moved by electrolysis. Carbonates and oxides are fused
with coal to reduce the metal. Sulphide ores containing
iron require complex treatment; in Montana the pro-
cedure is as follows : Partial oxidation by roasting, and
subsequent fusion in Bessemer converter (with silicious
lining) during which sand and air are blown through the
molten mass. The iron is oxidized and combines with
silica forming a slag, which floats on the copper. Sul-
phur, arsenic and lead are oxidized and volatilized.

1 The term "cuprum" was derived from the island of Cyprus in
the Mediterranean, where copper was first mined and extracted.

HOUSEHOLD CHEMISTRY 51

Copper is refined by electrolysis in the following
manner: Thin copper sheets coated with graphite are
suspended in tanks of copper sulphate solution and
connected with the negative pole of the dynamo ; opposite
are heavy plates of crude copper connected with the
positive pole. Pure copper is deposited on the cathode,
while the SO4 ionizes the anode. The impurities not
ionized fall to the bottom of the tank.

Properties. — Copper is a red metal melting at 1,057°.
It is a good conductor of heat and electricity, is very
malleable and ductile, and has a specific gravity of 8.9.
Several oxides of copper are known; two important ones
are the black or cupric oxide, CuO, and the red or cuprous
oxide, Cu2O. The latter forms slowly in dry air; in
moist air green basic carbonate (not verdigris) is formed.
Copper utensils are often lined with tin to prevent the
formation of this coating. When free from oxide cop-
per resists the action of alkalies, organic acids and most
mineral acids, and is much in demand for the manu-
facture of apparatus used in food preparation, e. g.,
vacuum pan for sugar, milk, etc., apparatus for canning
and preserving, candy making and beer brewing. Large
hotels and restaurants use copper cooking utensils.

The most important alloys of copper are :

Brass, containing 18-40% Zn

Bronze, containing 11% Zn, 3-8% Sn, some Pb

Gun metal, containing 10% Sn

Bell metal, containing 25% Sn

German silver, containing 19-44% Zn, 6-22% Ni

Brass is essentially like copper in its properties.
Metallic copper and its alloys are readily cleaned with

52 HOUSEHOLD CHEMISTRY

dilute oxalic acid or ammonia. In the laboratory tar-
nished copper may be cleaned as follows :

EXPERIMENTS.

i. Heat a piece of tarnished copper wire in the upper part of
the Bunsen flame. Note the change from cuprous to cupric
oxide. When the wire glows drop it immediately into a test
tube of methyl alcohol. What is the odor observed? Note the
appearance of the copper. Complete the reaction: CH3OH -j~

2. Heat small pieces of clean and tarnished copper in the
reagents described in experiment (i), p. 47. Finally pour off the
liquids and add to each an excess of ammonia; a blue color
shows the presence of copper. Have the pieces of copper been
visibly affected? Write the reaction between CuCl2 and NH4OH.

3. Compare the heat conductivity of copper and iron by hold-
ing the ends of copper and iron wires of equal length and size
in the Bunsen flame.

Aluminium, often called aluminum, is the most abun-
dant of the elements, with the exception of O and Si.
It is not found in the metallic state, but exists as sili-
cates in various clays, in the topaz, garnets and feldspar ;
as a hydrated phosphate in the turquoise; as an oxide
in corundum, in the sapphire, ruby, emery, etc., and in
bauxite, from which it is prepared commercially.

The method of preparation consists in powdering the
bauxite, freeing it from water and organic impurities,
and heating it with caustic soda solution under high
steam pressure. By the addition of alumina, aluminium
oxide or alumina is then precipitated from the product
in the form of a hydrate. The final process is the re-
duction of alumina by electrolysis. A substance called

HOUSEHOLD CHEMISTRY 53

cryolite, which is a compound of aluminium, sodium and
fluorine, melts at a low temperature and easily dissolves
alumina. A molten mixture of the two is connected with
one terminal of an electric generator, and the current is
introduced into the mass by means of a number of carbon
rods dipping below the surface. Decomposition by elec-
trolysis results, and the aluminium collects in molten
form at the bottom of the mass, from whence it is drawn
off. The reaction taking place is usually expressed as :

2A1203 + 3C — 4A1 + 3C02.

Properties. — Aluminium is silver-white in color, almost
as hard and tenacious as steel, and ranks next to copper
as a conductor of heat and electricity. It can be drawn
to extremely fine wire and beaten to a film 1/400oo °f an
inch in thickness. A film of oxide which forms on its
surface is protective. Its specific gravity is only 2.6, and
its melting point 600-700°.

Aluminium is readily reactive with alkalies and hydro-
chloric acid, and slightly so with organic acids, an action
which is increased if sodium chloride is present or if the
metal is tarnished. On account of its lightness it is much
in demand for cooking utensils, but care must be taken
that it does not come in contact with caustic alkalies. It
discolors readily, and should be cleaned with a neutral
scouring powder, or neutral soap and ammonia. Oxalic
acid in hot dilute solution will remove any discoloration
but will soon roughen the surface of the metal.

Several alloys of aluminium are known, the principal
ones being bronzes. The true aluminium bronzes are
compounds of Cu and Al alone, but various other metals

54 HOUSEHOLD CHEMISTRY

such as Zn, Ni, and Mg, are also introduced. Aluminium
has been added to brass with good effect. Other alloys
are combinations with Fe, Bi, Sn and Ag. Magnalium is
a useful alloy containing from 2 per cent, to 10 per cent,
of magnesium. It takes a high polish and works well in
the lathe.

Aluminium is of two forms in cooking utensils: cast,
and rolled or spun. In the former, copper is added and
the utensil is cast in one piece. The spun articles are
made from sheets of aluminium rolled to the required
thickness and drawn to the desired shape on a machine.

EXPERIMENT.

Test bright and tarnished aluminium as in experiment (i), p.
47. Filter. Neutralize the acid solutions with ammonia in the
presence of ammonium chloride and the alkaline solutions with
HC1. Note the precipitates and write the reactions.

Silver is found native with copper and gold, and also
as a sulphide, associated chiefly with galena (lead sul-
phide). Small amounts are obtained from antimony and
arsenic compounds, and in the form of silver chloride.

In the electrolytic refining of copper (p. 51) silver is
separated from the bath. The principal methods of ex-
tracting silver from its ores are (i) amalgamation; (2)
lixiviation; (3) smelting.

In the amalgamation process the chloride, bromide,
etc., are brought into prolonged contact with mercury,
which reduces the silver from its compounds and forms
an amalgam with it. Complex sulphides of silver resist
amalgamation and must have a preliminary treatment
consisting in roasting the ore with common salt or with

HOUSEHOLD CHEMISTRY 55

copper compounds to produce silver chloride. This was
the patio process used in Mexico for 350 years, and only
recently superseded by the cyanide process, described
under lixiviation.

In the lixiviation processes the silver is dissolved from
its ores by aqueous solutions and is precipitated as the
metal or as a sulphide. The cyanide method is the most
important. It is a complicated process. In brief, the
ore is crushed fine, mixed with cyanide solution, and the
pulp kept in contact with the solution until the dissolution
of the silver is complete. The mass then passes into
vacuum filters, and silver is precipitated from the clear
filtrate by either zinc dust or zinc shavings. Smelting
with nitre follows. The silver thus produced is impure,
and is carried through a refining process.

Smelting is a process applied to silver ores containing
large percentages of lead and copper. From the blast
furnace the silver comes out associated with lead as pig
lead or "base bullion." The amount of silver is seldom
over 2 per cent. It is separated from the lead by the
process of zinc desilverization and cupellation. Zinc and
lead are quite insoluble in each other and silver is more
soluble in zinc than in lead. Taking advantage of these
facts, the process is operated as follows: silver lead is
melted in large cast iron kettles and the zinc added and
well stirred. On standing and partially cooling, the zinc,
carrying silver and a little lead, rises and forms a crust
which is skimmed and heated in retorts to drive off zinc.
The residue, lead and silver, is then heated in a rever-
beratory furnace (cupellation) with bone ash bed. The

56 HOUSEHOLD CHEMISTRY

lead oxidizes, melts and is absorbed by the bone ash,
leaving the silver.

Properties. — Silver is a white metal, softer than copper
and harder than gold. It is highly ductile and malleable,
and the best conductor known of heat and electricity.
Its specific gravity when cast is 10.5, and its melting
point about 960°. It does not oxidize readily in air, but
is rapidly attacked by sulphides, producing a black coat-
ing of Ag2S.

Oxidized silver is made by dipping silver articles in a
solution of potassium hydrogen sulphide, which produces
a film of silver sulphide.

Silver dissolves readily in nitric acid, is somewhat re-
active with most other mineral and organic acids, but
not at all with alkalies.

In order to harden silver, it is alloyed with copper in
the following proportions : coin silver, 900 parts silver,
100 parts copper ; sterling silver, 925 parts silver, 75 parts
copper. All solid household silver is now "sterling."

Many silver ornaments contain even less silver, but
articles stamped "sterling" are trustworthy. Silver
plated ware consists of articles fashioned of German
silver or pewter, on which is deposited by electrolysis a
triple or quadruple coating of pure silver. The process
is similar to copper plating, the silver bath consisting of
potassium silver cyanide, KAg(CN)2. The coating has a
frosted appearance and needs burnishing or smoothing
before use. Since the coat deposited in this manner is
pure silver, these articles do not stand as much careless
and rough handling as the harder sterling or coin ware,

HOUSEHOLD CHEMISTRY 57

and much of the coating is rubbed off in the process of
cleansing with the so-called silver polishes. Plated ware
will last much longer if simply washed with hot water
and neutral soap. In order to remove the tarnish due to
sulphides (eggs), soak the articles in a clean tin or
aluminium pan containing enough baking soda solution
to cover and let them remain until bright. The soda
solution is made by dissolving a tablespoonful of
NaHCO3 in a quart of tepid water. Or the water may
be made to boil over the silver and the soda added.

Tin, (Stannum) Sn, occurs in Cornwall, Wales, and
the East Indies as Cassiterite (tin stone), SnO2. The
ore is crushed and washed to remove rock, roasted to
oxidize sulphide of iron and copper and to remove arse-
nic, then leached with water to dissolve sulphate of iron
and copper, dried and reduced with coal in a reverbera-
tory furnace.

Properties. — Tin is a soft, silver-white, crystalline
metal, malleable but not tenacious. It melts at about
230°. Its specific gravity is 7.3. On bending bar tin a
peculiar crackling sound, called the "cry of tin," is heard,
caused by the friction of interlaced crystals. Pure tin
resists oxidation in moist air, and is not quickly sus-
ceptible to the action of dilute acids and alkalies. How-
ever, there are certain fruits and vegetables which attack
the coating of a tin can to some extent, forming salts of
tin which are objectionable. A lacquered can is prefer-
able for raspberries, cherries, plums, beets, pumpkin,
hominy, etc. On the other hand, cases of poisoning
traced to canned foodstuffs may have been caused either

58 HOUSEHOLD CHEMISTRY

by the imperfect condition of the food when canned or
by careless soldering. The latter evil is now largely done
away with by present methods of sealing tin cans.

Tin plate is made by dipping carefully cleaned sheets
of iron or steel in molten tin. It is much used for roof-
ing, household ware and cans for preserving food. Care
must always be exercised that tin vessels are not over-
heated, since the element has a low fusion point and will
run off leaving the iron bare, therefore it should never
be used in the oven or for broiling, roasting or frying.
Liquid mixtures may be cooked in tin vessels without
doing any damage.

Various useful alloys are known, viz., bronze, soft
solder (half tin, half lead) ; plate pewter, antimony, bis-
muth and copper; Britannia metal, 10 per cent, antimony.

EXPERIMENTS.

1. Heat a small piece of tin plate over the Bunsen flame, note
the crystalline appearance on cooling; treat a piece with mod-
erately strong acid and note a similar effect. Where have you
frequently seen this phenomenon?

2. Subject pieces of bright and tarnished tin to the action of
dilute acids and alkali as under iron. Test the filtered liquids
for soluble tin compounds by acidifying with HC1 and adding
mercuric chloride. A white precipitate of mercurous chloride
results, passing to a gray precipitate of metallic mercury, if
sufficient stannous chloride is present, the tin acting as a reduc-
ing agent as follows:

SnCl2 + 2HgCl2 ^ SnCl4 + 2HgCl,

2HgCl + SnCl2 ~-+ SnCl, -f Hg2.

Write the reactions for the action of HC1, CHSCOOH and
NaOH on tin. (NaOH produces sodium metastannate as the
final product.)

HOUSEHOLD CHEMISTRY 59

Lead, Pb (Plumbum), occurs principally as galena,
PbS (frequently carrying silver). The metal is obtained
by roasting the ore until partially converted into oxide
and sulphate. On closing the furnace doors and increas-
ing the heat, the charge is reduced to metal :

PbS + 2PbO ~- sPb + SO,.
PbS + PbSO — 2Pb + 2S0.

Lead is gray in color, soft, of slight tensile strength but
very malleable. Melting point 325°-335° and specific
gravity about 11.3. It is only slightly soluble in acids and
alkalies, but its oxide is very soluble. Lead pipes are
formed by forcing warm lead through steel dies by
hydraulic pressure. They are largely used for conduct-
ing water in the household. The danger of drinking
water conducted by lead pipes is much exaggerated.
Unless the water is unusually soft, the interior of the
pipe quickly becomes coated with insoluble sulphate and
carbonate. A wise precaution with new plumbing is to
allow the water to run for some minutes before use.
Lead enters into many useful alloys previously men-
tioned.

Lead oxidizes superficially, the compound formed
being the black suboxide, Pb2O, formerly used in place
of graphite for lead pencils.

The crystalline character of lead and some of its com-
pounds can be shown by the following:

EXPERIMENTS.

I. Dissolve two small portions of lead oxide, one in dilute

HNO3 and the other in acetic acid ; pour a little of each solution

in two separate watch-glasses and set them aside to evaporate.

Examine the crystalline residue in each case. Scrape two pieces

5

6o

HOUSEHOLD CHEMISTRY

of lead bright and immerse one in strong nitric acid, the other
in acetic acid; allow them to stand several days, then examine,
and compare with the crystals found above.

2. Immerse bright lead in water charged with carbon dioxide;
after several hours' standing pour off the water and test it with
hydrogen sulphide.

3. Treat small pieces of bright and tarnished lead separately
in weak solutions of acids and alkali as under iron. Pour off
the clear solutions, acidify with HNO3 where necessary, and
test for lead by passing H2S through the liquid. A black pre-
cipitate (PbS) indicates lead.

Summary. — Each student should make a tabular state-
ment comparing the metals of the household with regard
to action with acids and alkalies, cost, durability, sus-
ceptibility to oxidation, methods of cleaning, heat prop-
erties, etc.

USEFUL TABLES.

Heat
conductivity

Specific
heat

Density

Qj] v^r

IOO.OO

73-o
48.0
23.0
19.0
15-0
14.0
11.9
H.6
8.4
0.24

0.2

0.16

0.001

0.056
0.094
0.218

0.086
0.093
0.055
O.IC9

O.H5
O.II7
0.032
0.2
0.2
0.2
0.194

10.50

8-93
2.65

7.10

7.29
8.90
7.86

21.50

Tin

Nickel

Steel .

CHAPTER V.

GLASS, POTTERY, AND PORCELAIN.

These materials belong to a series of infusible and
insoluble silicates of great utility in all household opera-
tions. Glass consists of a mixture of silicates in the
amorphous state and is highly prized on account of its
brilliancy and transparency; the mass may be colored
without affecting either of these qualities. The usual
varieties of glass consist of a mixture of alkaline (with
alkaline earth) or heavy metal silicates, and are known
as Bohemian, Crown, Bottle and Flint glasses.

Bohemian glass is a silicate of potash and lime. It is
very infusible and insoluble, therefore especially adapted
for chemical purposes.

Window or Crown glass is a silicate of soda and lime.
It is more fusible but harder than the Bohemian and is
more easily affected by acids.

Bottle glass is an impure variety of the above, colored
with iron.

Flint glass is a potash lead silicate. This is the most
fusible kind of glass and is easily attacked by chemical
reagents; on account of its high refractive power, it is
much used for optical purposes.

All kinds of glass are prepared by fusing more or less
pure silica in the form of sand or powdered quartz with
the potash or soda and lime or red lead, for many hours
in large earthenware pots, heated in appropriate fur-
naces. When the mass has cleared, it is cast or blown
and cooled rapidly in order to retain its transparency.

62 HOUSEHOLD CHEMISTRY

Annealing is a process of heating to a temperature
short of softening and cooling slowly, thereby reducing
the brittleness.

While transparency is a very important property of all
glasses, there are several useful opaque forms. Opaque
glass is the result of suspending finely divided infusible
material in the molten mass. Such materials are bone
phosphates, cryolite, zinc or tin oxides, etc. The enamels
used on cooking utensils are of similar composition, and
should be handled with the same care as glass articles.
On account of the great difference in the expansion co-
efficients of the glaze and metal base, too sudden cooling
or heating of the utensil should be avoided. Likewise
judgment and care should be exercised in the selection
and use of cleansing agents. Pure neutral soap is the
best medium to employ, and under no circumstances is
the use of strong caustic alkalies or sharp abrasives jus-
tified.

One of the most characteristic properties of all glasses
is the solvent effect of hydrofluoric acid and soluble
fluorides. Etching on glass is largely accomplished by
this means.

Colored glass is the result of dissolving some appro-
priate mineral oxide in either variety of glass :

Ruby — oxide of gold or copper.

Topaz — sulphide of antimony.

Yellow — silver chloride or borate.

Green — oxide of chromium.

Blue — oxide of cobalt.

Amethyst — oxide of manganese.

HOUSEHOLD CHEMISTRY 63

EXPERIMENTS.

1. Corrosive Action of Alkalies.— Half fill common prescription
bottles (4 oz.) with strong caustic soda solution. Place them in
warm salt water, bring slowly to a boil and continue for at least
i hour, then cool slowly, pour out the contents, rinse with clean
water and examine the inner surface.

2. Etching Tests.— (a) With a clean steel pen and dilute hydro-
fluoric acid, HF, write your name and the date on a clean
microscope slide.

(&) Thinly cover a clean watch-glass with warm paraffin.
When cool cut your name with a pencil point through the paraf-
fin and immediately invert over a lead dish containing a mixture
of fluorspar and concentrated sulphuric acid. After half an
hour's gentle heating, rub off the paraffin and examine the
result.

3. Detection of Arsenic, Lead, Etc.— Fuse finely ground chips
of kitchen utensil enamel with an excess of potassium sodium
carbonate in an iron or nickel crucible, cool and extract the
melt with hot water. Filter and wash the residue several times
with hot water. Test the filtrate for arsenic, lead, and acids,
by dividing it into 3 parts — two of one-quarter each and the
third the remaining half.

Part I. Test for arsenic by making strongly acid with HC1
and boiling with a strip of clean copper. A gray or black coat-
ing indicates arsenic.

Part II. Make acid with HC1 and pass H2S rapidly through
the solution. A black precipitate indicates lead.

Part III. One-half of the solution— test for sulphates, borates,
phosphates, and silicates, as follows:

Neutralize with HC1 ; if any precipitate forms, filter and divide
the filtrate into 3 parts. The residue is silicates. Take i part
of the filtrate, thoroughly moisten a strip of turmeric paper with
it and dry at 100° C. A pink color indicates borates.

To another part, add barium chloride and a few drops of HC1.
A white crystalline precipitate indicates sulphates. Pour a few

64 HOUSEHOLD CHEMISTRY

drops of the remaining part into an excess of ammonium molyb-
date. Warm gently and a yellow color or yellow crystalline
precipitate indicates phosphate.

Porcelain and Pottery are fused silicates of alumina,
trie former pure, and the latter contaminated with oxides
of iron, manganese, etc.

The primary source of these wares is clay, a highly
infusible hydrated silicate of alumina. For porcelain
making it is mixed with some fusible silicate such as
feldspar, and a small quantity of water, moulded into
shape, dried and heated in a furnace for many hours.
The feldspar or flux only melts and running through the
porous mass cements it together. Even after firing, the
ware requires coating with the glaze, a mixture of
slightly fusible material suspended in water into which
the article is dipped. It is dried and returned to the fur-
nace for heating. The glaze is, in effect, a true glass and
makes the mass impenetrable to liquids. Decorative
effects are produced in two ways, called under- and over-
glaze, of which the former is the better and more per-
manent. For under-glaze work, finely ground colored
glass suspended in turpentine is applied to the unglazed
ware and afterwards "fired" at the high temperature of
the porcelain furnace. The glaze is subsequently applied
and fired as before. Over-glaze decoration admits of
the use of colors which may be injured by the high heat
of the porcelain furnace and is applied at a lower tem-
perature in a muffle. The colors consist of various
oxides mixed with borax, litharge, nitre, etc. They are
applied in watery solution.

HOUSEHOLD CHEMISTRY 65

Stoneware is an impure form of porcelain, somewhat
more fusible and usually glazed with borax. The finer
qualities are known as china. Earthenware and brick
consist of clay and sand, mixed with water, moulded,
dried and fired in a kiln. The former is usually glazed
with salt, while the latter is left in the porous state.

Since most of our decorated table china is over-glaze
ware it is likely that it will not successfully withstand
repeated washings, especially since modern practice has
brought into use many forms of alkaline detergents, i. e.,
soap powders and cleaners. Some of these contain
bleaching agents, which liberate chlorine and are there-
fore destructive to gold, but prolonged contact with the
strong alkalies in their composition is sufficient to hasten
the removal of both gold and color decoration.

EXPERIMENTS.

1. Heat several decorated dishes in new enameled saucepans
with solutions of various soaps and other cleansers. Keep the
pans covered and boil gently for i hour. Cool, rinse in clear
water, and examine the effect, both on the china and the sauce-
pan.

2. Porosity. — Weigh small pieces of dry unglazed porcelain
and earthenware, soak over night in water, wipe dry and weigh
again. Calculate the per cent, of water absorbed.

3. Fusibility.— Heat small splinters of porcelain and earthen-
ware held in platinum wire (spiral) at the highest heat of your
burner. Cool and examine with a magnifier. Are the edges
sharp or rounded?

4. Testing for Lead in the Glaze.— Boil the article for some
time in caustic soda, cool the liquid and add (NH^aS. A dark-
ening of the liquid or a black precipitate due to lead sulphide,
PbS, indicates lead.

CHAPTER VI.

FUELS.

Fuels are materials used for producing heat; they
must be capable of uniting with oxygen under easily
obtainable conditions and of evolving much heat energy
during the process of combustion. Occurring as gases,
liquids and solids, carbon and its compounds largely fill
the required conditions.

Classification. — A logical arrangement of the fuels
would result as follows :

Natural J Hydrogen

1 Hydrocarbons

Pure fuels Gases

] Carbon
Artificial - monoxide

I Hydrocarbons
[ Natural Hydrocarbons

f Alcohols

I Artificial | Hydrocarbons

f Natural Anthracite

Solids f Coke

I Artificial { charcoal

[ Soft coal

Impure fuels Solids Natural 1 Peat

[ Woods

Coals, petroleum and natural gas are evidently of plant
and animal origin, produced by a natural method of
decomposition, similar to a process of dry distillation.

The terms pure and impure are used in a restricted
sense, the former signifying that the substance is ready
for direct combustion while in the latter case a number
of complicated chemical changes must take place before

HOUSEHOLD CHEMISTRY 6/

combustion is possible. This is explained in detail in
the discussion of the composition of wood.

Historical: Woods both hard and soft and charcoal
have been used from the earliest times. Peat, a form of
partly carbonized turf, was the main fuel of European
countries during the Middle Ages and is still in use.
Soft coal came into use during the I5th century, while
gas and hard coal were first employed in the early part
of the iQth century, and hydrocarbons about the middle
of the same epoch. Alcohol is just coming into general
use in our own times.

Impure solid fuels on account of more extended use
will be first discussed.

Wood, peat and soft coal are such impure forms of
fuel and must undergo so many and such complicated
chemical changes before they are capable of yielding
heat, that their actual fuel value is frequently over-esti-
mated and rarely understood by the consumer. The fol-
lowing is a brief and simple statement of composition
and changes to be expected :

Wood contains, moisture, (H,O); resin, (C^H^);
starch, gum, and cellulose, n (C6H10O5) ; oil, (C^H^O*):
mineral matter or ash.

Considerable heat is required to drive off the moisture
and raise the starch, cellulose, etc., to such temperatures
that they will decompose, yielding gases of a combustible
nature, for example CO, CH4, C2H4, C2H2, H2; in this
decomposition H2O is formed and must be driven off as
a gas. Much heat is also absorbed by the ash in form-
ing new chemical compounds. In fact the fuel efficiency

68 HOUSEHOLD CHEMISTRY

of wood depends entirely upon the relative volumes of
combustible gas and charcoal furnished, and as the char-
coal or carbon is the best solid fuel, the wood furnishing
the largest proportion of carbon in this form is the best
fuel, hence we find it advantageous to use hard wood.
It must be understood that carbon or charcoal at a red
heat combines with a limited amount of oxygen and
forms a combustible gas, carbon monoxide, CO, a fuel of
the highest heating efficiency.

Soft Coal, a partly carbonized plant product, produces
less water by chemical change and yields the combustible
gases and carbon (coke) in larger proportion.

Hard coal is superior to soft, since it is a purer form
of carbon and yields very little combustible gas.

EXPERIMENT.

To determine the value of coal or wood for fuel purposes,
proceed as follows: Take I gram of pulverized coal or small
pieces of wood in a weighed crucible, dry at 120° with cover
off, cool and weigh; the loss is water. Heat the crucible with
cover on in a strong Bunsen flame for 7 minutes, cool and weigh ;
the loss is volatile combustible matter (tar, smoke, etc.). Heat
again with cover off until nothing remains but ash. This opera-
tion will require some time; cool and weigh; the loss is fixed
carbon (actual fuel). Subtract the weight of the crucible; the
difference is ash.

The quantity of ash in coals is always greater than in
wood, owing to the presence of foreign mineral sub-
stances such as silica, lime and sulphide of iron derived
from the earthy strata in which the coal is deposited.

Flue dust, collecting in stove pipes and flues where
hard coal is burned, contains sulphate of ammonia.

HOUSEHOLD CHEMISTRY 69

When cool, this salt absorbs water and attacks iron,
rapidly corroding the pipes. This fact explains the neces-
sity of cleaning the smoke pipes of furnaces and stoves
in the spring of the year when the heating apparatus is
no longer used.

EXPERIMENT.

Collect some of the light gray dust from a smoke pipe, treat
about i gram with boiling water on a filter, pouring the liquid
through several times. Reserve the residue and test the liquid
in the usual manner for ammonia and sulphates. Extract the
residue still on the filter-paper with boiling dilute HC1 until
the residue is light in color. This is mainly silica from the coal
ash. Test the acid filtrate for ferric iron and lime in the usual
manner.

Liquid Fuels. — These comprise alcohols, and hydro-
carbons in the form of gasoline or naphtha, and kero-
sene. The hydrocarbons are highly inflammable liquids
obtained from crude petroleum.

The distillation of petroleum was carried on in Europe
early in the i8th century, and there is evidence of the
use of the crude oil by fire worshippers as far back as
Zoroaster. The great oil region of Europe is the Baku
peninsula on the Caspian Sea. Crude petroleum was
known to the Indians in America, and in New York
State it became popular as a specific for rheumatism,
under the name of Seneca Oil. Refined petroleum in
the United States dates from 1855, when it was distilled
and put on the market as a patent medicine called Amer-
ican Oil. Up to this time a limited quantity had been
obtained at or near the surface of the ground. In 1859,
in Titusville, Pa., Col. Drake applied the method of

70 HOUSEHOLD CHEMISTRY

boring artesian wells to obtain petroleum from under-
lying strata, and the industry was revolutionized. In
that year 2,000 barrels of crude petroleum were produced,
2 years later 2,000,000, and in 1910 210,000,000 barrels.
The new supply gave a material more profitable for refin-
ing than shale oil. By fractional distillation at first, a
number of distillates were obtained ranging from petro-
leum ether, naphthas, gasoline, etc., to solid paraffins.
The yield of gasoline by this process was entirely insuffi-
cient, however, to meet the sudden demand created by
the automobile and motor engines, so a system of "crack-
ing" was devised, which has greatly increased the light
oil distillate and is better suited to the refining of oils
from the newer western fields.

Cracking Process. — This is a method of distilling at a
temperature higher than the normal boiling points of
the constituents to be obtained, which effects a dissocia-
tion of many of the heavier oils into lighter hydrocar-
bons. As the process is conducted in some places, the
charge of oil (about 1,000 barrels) is put into a side-
firing still, the temperature is raised to 600° or 700° F.,
and the vapors as they come off are carried to a series
of condensers, where they are separated, the heaviest
vapors condensing first, the lightest traveling farthest
before being condensed. The vapors of a considerable
amount of the oil intermediate between kerosene and
lubricating oils are returned to the still, superheated, and
decomposed, so increasing the yield of light distillate.
Usually 3 streams of oil of different specific gravities
are simultaneously received : the heaviest, or the paraffin

HOUSEHOLD CHEMISTRY Jl

oil distillate; the intermediate, or gas oil, and the light
oil distillate. The paraffin oil distillate is worked up
to produce lubricating oils, paraffin, etc., the interme-
diate distillate is refined for burning and gas oils, and the
light distillate is fractionally distilled and yields a num-
ber of important compounds, such as :

Cymogene, specific gravity 110° Baume. Used in the
manufacture of ice.

Rhigolene, specific gravity 100° Baume. Used as an
anaesthetic.

Petroleum ether, 85°-8o° Baume. Used as a solvent
and for carbureting air in gas machines.

Benzine, 89°-82° Baume. A solvent.

Gasoline. Varies widely in specific gravity and qual-
ity, according to the demand. It may have a specific
gravity of 8o°-6o° Baume.

For the purification of petroleum products the use of
sulphuric acid followed by soda lye is universal. Aro-
matic hydrocarbons, fatty and other acids, phenols and
tarry bodies are thus decomposed or removed. Sulphur
compounds are taken out in the form of sulphides by
copper.

Chemical Nature of Petroleums. — Crude petroleum from
different fields shows great differences in chemical con-
stituents. The Pennsylvania petroleum yields hydro-
carbons of the methane series principally, compounds
from C4H10 to C35H72 having been isolated in almost
unbroken sequence, with many of their isomeric forms.
Ring hydrocarbons such as benzene, C6H6, have also been
found in smaller quantity.

72 HOUSEHOLD CHEMISTRY

The California oils are of varied character and con-
sist of a more or less dense asphaltic base. Asphalt is
usually regarded as evaporated and oxidized petroleum.
Phenols are common constituents; nitrogenous ring
compounds and the defines from C2H4 to C30H60 inclusive
have been obtained. The California field is very active,
a single well having made a record of 30,000 to 60,000
barrels per day.

The Texas oil seems to combine the characteristics of
the Pennsylvania and the California types, while the mid-
western field produces both kinds.

Russian and Cuban petroleum consist largely of the
unsaturated hydrocarbons of the naphthene series,

Cn Ha«_6 -f- H6.

The depth at which petroleum is found is of interest.
In Pennsylvania wells range from 300 to 3,700 feet; in
California they have been drilled to a depth of over
4,000 feet.

Products of Combustion. — At temperatures slightly
above normal liquid fuels readily combine with oxygen,
producing intense heat and yielding water and carbon
dioxide as products but no ash; with too small supply
of oxygen the temperature of combustion is much low-
ered and a large part of the carbon is not consumed and
escapes in a free state, producing a yellow flame and if
in great excess much black smoke — a very familiar phe-
nomenon in kerosene lamps.

With great excess of oxygen, as when the hot vapor
of these liquids is mixed with many times its volume

HOUSEHOLD CHEMISTRY 73

of air, in a confined space, the combustion is so rapid
as to produce an explosion (automobile engine). When
using these products for fuel purposes care must be
taken that these last conditions do not exist. Hence as a
measure of safety the lamp or stove reservoir is kept
well filled and cool. The following simple experiments
will serve to impress these important facts on the
student's mind: —

r

EXPERIMENTS.

1. Pour not more than I or 2 drops of clear gasoline into a
clean, dry, wide-mouth bottle of 12 to 16 ounces capacity, stir
the vapor for a moment with a hot glass or iron rod and bring
a lighted match over the mouth of the bottle; a slight but per-
ceptible explosion should result with or without blue flame.

2. Pour a teaspoonful of the same liquid in a shallow porcelain
dish or saucer, apply the lighted match and note the yellow
flame, but no explosion. Quench by covering with cloth, stiff
cardboard or any article that will exclude air.

Gasoline is used quite largely in some localities as a
source of heat, being consumed in the so-called blue
flame stove, which operates by heating the liquid to such
a temperature, air being excluded, that vapor forms rap-
idly and under slight pressure. It is then conducted to
the burner (Bunsen), mixed with the proper amount of
air, and burns with a blue flame. These stoves and
heaters are perfectly safe as long as they are kept clean,
do not leak liquid, are kept well filled and furnished
with good gasoline. The quality of gasoline may be
determined by the following tests :

1. Observe the color; it should be white as water.

2. Clearness; if cloudy, dirt or water is present Evaporate

74 HOUSEHOLD CHEMISTRY

a small quantity in a clean porcelain dish over warm water (no
flame) and examine the residue; also filter some through clean
dry chamois skin. Water and dirt will remain on the skin. It
is a wise precaution for users of gasoline for any purpose to
filter as above before using.

3. Test with delicate litmus paper; it should be neutral.

4. Determine the specific gravity with the Baume hydrometer
for light liquids; it should register not higher than 62° for fuel
purposes.

Kerosene, erroneously called an oil, is much more
extensively used and widely known; it is probably the
cheapest and best liquid illuminating agent of the present
day. The ordinary kerosene wick lamp is so well known
as to need no explanation. Kerosene, however, is used
in blue flame stoves, such as the Khotal, etc., and although
more troublesome to manipulate is preferred by most
people because the danger is minimized.

Kerosene should successfully stand tests i, 2, 3, given
under gasoline. The specific gravity should be 48°
Baume.

In addition, flash and fire tests are prescribed in most
parts of the world. The former signifies the temper-
ature at which the oil gives off ignitable vapor, and the
latter the point at which it takes fire. The experiment
below represents the open-cup method of determining
the flash point, the figures of which are always slightly
lower than by other methods :

Half fill a 200 cc. beaker with kerosene, place over warm
water, stir gently with an accurate Fahrenheit thermometer and
heat slowly not more than 2° rise per minute, until a small open
flame brought over the surface of the liquid causes a blue flame

HOUSEHOLD CHEMISTRY 75

and slight explosion. Note the temperature; it is the flash point
and should not be lower than 100° F. Air currents and draughts
should be excluded in this experiment.

Kerosene and gasoline are unsaponifiable. Prove this
in the case of kerosene by the following:

Heat a small quantity of kerosene with one-seventh its volume
of a solution of sodium hydroxide (38° Baume) over hot water,
stirring often. On cooling, does the product resemble soap? Is
kerosene rightly called an oil?

The increased efficiency of kerosene as a burning fluid
in recent years is partly due to the presence in its com-
position of unsaturated hydrocarbons, formed during the
cracking process. These have a higher illuminating
power than the former saturated type found in the oil.

Alcohols. — Of this series, only methyl or wood alcohol
and ethyl or grain alcohol are used as fuels. A mixture
of the two (90 parts ethyl, 9 parts methyl -|- I part ben-
zine) has come into general use under the name of de-
natured alcohol; it is essentially ethyl alcohol. Methyl
alcohol, CH3OH, is produced commercially by the dry
distillation of wood and is known as pyroligneous or
wood spirit ; it contains light wood tar, acetone, and acetic
acid, which should be completely removed before using,
leaving a bland mild-smelling liquid similar to ethyl alco-
hol, known as Columbian Spirit. Much of the ordinary
wood alcohol is quite impure. Tar and acetone are easily
distinguished by the color and odor, especially if gently
heated ; acid is readily shown by litmus paper.

As a burning fluid methyl alcohol is distinctly inferior
to grain alcohol. The following equation shows the
6

76 HOUSEHOLD CHEMISTRY

chemical change during complete oxidation: 2CH3OH
+ 302 — 4H,0 + 2C02.

In stoves or lamps of the best type, ethyl or grain
alcohol burns as follows :

C2H5OH + 302 ~ 2C02 -h 3H20.

Comparing this equation with that of methyl alcohol
it will be seen that the amount of CO2 is doubled, hence
it is fair to assume that the heating effect is greater;
ethyl alcohol is less volatile than methyl, therefore loss
by evaporation during use is less.

Methyl alcohol is readily oxidized to formaldehyde by
means of hot copper oxide (see Experiment i, p. 52).
This serves as a test for the identification of this alcohol.
By further oxidation methyl alcohol yields formic acid:

CH3OH + 02 -~ HCOOH + H2O.

Ethyl or grain alcohol, C2H5OH, is prepared by the
fermentation of glucose or maltose by means of yeasts
and distillation of the product. It is a colorless liquid
with pleasant and characteristic odor, usually containing
about 95 per cent, of pure alcohol and the balance water
and small amounts of impurities, acetic acid and acetone
more especially; these are not particularly objectionable
if the liquid is to be used for generating heat or general
solvent purposes, but in many chemical operations
further purification is necessary. Pure alcohol, free
from aldehyde and acid for chemical purposes, can easily
be made from the ordinary 95 per cent, variety or even
waste alcohol by allowing it to remain for several days

HOUSEHOLD CHEMISTRY 77

in contact with slightly rancid tallow or grease and sub-
sequently filtering, distilling and neutralizing the product.
On account of the high price, due to the government
tax, ethyl alcohol was formerly little used for heat and
power purposes, but since the introduction of denatured
alcohol, the cost has fallen and the use enormously
increased. At the present price, it is somewhat more
expensive to use than gasoline but far safer and pleas-
anter to handle.

EXPERIMENTS.

1. Determine the boiling point of 95 per cent, ethyl alcohol by
distilling 100 cc. in a small flask fitted with a thermometer and
condenser.

2. Determine the specific gravity of alcohol by means of the
hydrometer and check the result by the Westphal balance.

3. Ethyl alcohol combines with iodine in the presence of strong
alkali, forming iodoform:

C2H5OH -f 41, + K2C03 »-» 2 CHI, + C02 + 2KI + 2H2O.
To 20 cc. of a 10% solution of K,CO8, add 3 cc. of CaH5OH
and warm to 70° on a water bath. Add gradually about 5 cc. of
a 10% solution of iodine in KI, stirring meanwhile. Yellow
crystals of iodoform will appear.

4. By the use of an oxidizing agent such as KiCriOi, ethyl
alcohol is converted into acetaldehyde :

3C2H5OH 4- K2Cr,O7 + 4H2SO4 m~+

3CH3CHO + K2S04 + Cr2(S04)3 + 7H2O.
Heat 10 cc. of alcohol with I cc. of KaCraOr solution acidified
with sulphuric acid, notice the reduction of the chromium to
base and the odor of aldehyde.

5. Since ethyl alcohol oxidizes readily to acetic acid, some
acidity is found in most samples. The amount may be such as

78 HOUSEHOLD CHEMISTRY

to cause corrosion of metal containers or burners in alcohol
stoves. *•

Determine the acidity of 10 cc. of alcohol with N/io alkali,
calculating the percentage in terms of acetic acid.

Gases. — Gas consisting of hydrogen, carbon monoxide,
and various hydrocarbons is the ideal fuel. There are
seven varieties in use for fuel and lighting purposes, viz.:

Natural gas
Water gas
Coal gas

Gases proper 1 Acetylene gas

Blau gas
Pintsch gas

Naphtha or air gas r Cold air charged with naphtha
\ vapor.

Natural gas has been found in large pockets in the
earth in various localities for many years. The shrines
of antiquity were in some cases supplied with gas from
crevices in the earth; it is probable that the temple of
Diana at Ephesus had a natural gas well.

Fredonia, N. Y., was lighted with natural gas as early
as 1825. The supply was accidentally discovered when
boring for salt, as these earth pockets are reached by
drilling as for oil or brine. The gas comes out under
tremendous pressure, which must be controlled and re-
duced for household use. Its main constituent is meth-
ane or marsh gas, which has little or no illuminating
power, but is an excellent source of heat. The supply
of natural gas from earth pockets is gradually becoming
exhausted.

Three classes of natural gas are recognized :

HOUSEHOLD CHEMISTRY 79

(1) The gas which issues from marshy beds, and
contains methane as its only combustible constituent.

(2) Natural gas found in pockets occurring in oil
fields but not associated with oil. In this, methane pre-
dominates, but hydrocarbons higher in the series are
found. This is the gas which supplies Pittsburgh and
Cleveland.

(3) A gas associated with petroleum, called "wet"
gas, from which gasoline can be obtained. Natural gas
of this type is found in almost every oil-producing state
of the Union. By compressing this gas to 350 pounds per
square inch, and passing it through cooled condenser coils,
a gasoline is produced with specific gravity of 77° to 1 10°
Baume. Being extremely volatile, it is kept in tanks
under heavy pressure, and when drawn off is usually
mixed at once with low grade refinery naphthas. The
amount of gasoline obtained in the last few years from
natural gas has approximated 10,000,000 gallons annually.
The residual gas left after the gasoline extraction has a
high heating value and is utilized for that purpose.

Water Gas. — By passing steam at high pressure over
incandescent carbon a mixture of hydrogen and carbon
monoxide, known as water gas, is produced. The carbon
used may be in the form of anthracite, coke or even
charcoal. A high temperature is necessary for the
operation, usually about 3,000° F. Decomposition takes
place, the chemical change being as follows :

2H,O + C2 -~ 2CO + 2H,.

In order to give the resulting gases illuminating quality
they are mixed with light hydrocarbons and the com-

80 HOUSEHOLD CHEMISTRY

bination passed through a red hot zone. The naphtha
vapors are broken up (cracked) into permanent gases
such as methane, ethylene and acetylene, giving the prod-
uct a composition similar to coal gas (q.v.) but com-
bined in somewhat different proportions. Since it con-
tains more carbon monoxide it is generally regarded as a
better fuel.

Coal Gas. — From soft or bituminous coals, a gas can
be produced by dry distillation. This was the first
method used for making gas, and dates back to early
days of the ipth century. On account of the many and
valuable by-products produced, viz., ammonia, coal tar,
carbolic acid, naphthalene, cyanides, etc., it will probably
be used for many years to come.

The process consists in heating the coal in large clay
retorts, drawing off and cooling the gas in order to con-
dense tar, washing to remove ammonia, tar, etc., remov-
ing sulphur with lime or iron oxide, storing and deliver-
ing the gas under slight pressure. Essentially the same
process of purification is used with water gas. In recent
years the horizontal retort for the distillation of the coal
has been generally superseded by the inclined or vertical
type. The charge of coal is admitted at the top, and the
retort filled. When the distilling process is complete, the
bottom of the retort is opened, and the residue, coke,
falls out by gravity.

The changes which take place when soft coal is thus
burned out of contact with air are extremely compli-
cated. The products formed are gaseous, liquid, and

HOUSEHOLD CHEMISTRY

8l

solid. The liquid constituents which condense as coal
tar yield on further treatment a number of substances
such as benzol and anthracene, which are the basis of
thousands of important organic compounds. The gas-
eous products, which are combined as illuminating gas,
are conveniently classified as follows :

Impurities or diluents — oxygen, carbon dioxide, nitro-
gen.

Illuminants — ethylene, acetylene.

Gas proper — hydrogen, marsh gas or methane, carbon
monoxide.

Hydrogen sulphide is the only impurity in gas of any
importance ; by its combustion sulphur dioxide and water
are produced, finally resulting in sulphurous acid, which
readily attacks fabrics and metals and bleaches many
colors. Any hydrogen sulphide escaping combustion
blackens lead acetate paper held far enough above the
flame to be uninfluenced by the heat.

Analyses of gas are given below :

Water gas per cent.

Coal gas

o.o

12.6

0.9
27-3

27-7
27.7

3.8

0.0

6.5
0.9
6.8
41.1
41.0
3-7

IOO.O

254

IOO.O

21.32

82 HOUSEHOLD CHEMISTRY

In a water gas, the candle-power is usually double the
illuminants.

The value of gas is expressed as candle-power, the
unit being a standard sperm candle burning 2 grains
per minute; hence a 25-candle-power gas would give
as much light as 25 of the candles burning simultane-
ously. The calorific value of the gas should also be de-
termined as a measure of its quality for general purposes.

The standard illuminating burner consumes 5 cubic
feet per hour under a pressure of ij^ inches of water.
This is used as a unit in all gas calculations.

Two styles of meters are used — the wet and the dry;
in the former the gas passes through a revolving drum
partially submerged in water. The revolutions are regis-
tered on dials by appropriate clockwork. Since this
form of meter is liable to freeze and must always contain
water, some of which is lost by evaporation, it has been
largely superseded by the dry meter, which contains 2
bellows alternately full and empty. A clockwork device,
similar to that used in the wet meter, keeps record on
appropriate dials. Gas meters are subject to public test
and are allowed an error of 2 per cent, either fast or slow.

Chemical Changes During Combustion. — The common
burner can only use gas of the following composition:
methane, CH4, ethylene, C2H4, acetylene, C2H2, hydro-
gen, H2, and carbon monoxide, CO. Combustion pro-
ceeds according to the following equations :

HOUSEHOLD CHEMISTRY 83

CH, + 2O2 — CO2 + 2H2O — heat, no light.

2H2 + O, — > 2H2O — heat, no light.

2CO + O2 -^ 2CO, — heat, no light.

C2H4 -f O2 -~* 2H2O + C2 — less heat, some light.

2C2H2 -f O2«^ 2H,O 4- 2C3 — less heat, more light.

The Bunsen burner mixes the gas with O2 before
combustion; this affects only the ethylene and acetylene
as follows:

C2H4 + 3O2 •— aH,O + 2CO, — heat, no light.

2C,H, + sO2 •— 2H2O + 4CO, — heat, no light.

Acetylene gas, C,2H2, is made by the action of water on
calcium carbide as follows :

CaC, + 2H20 — C,H, + Ca(OH),

Calcium carbide is prepared by heating a mixture of
lime and charcoal in the electric furnace.

Either the water is sprayed on the carbide, or finely
pulverized carbide is sprinkled in water.

Acetylene is only used in places where ordinary gas
cannot be obtained, and is generally used at once. It
may, however, be stored in an ingenious manner; strong
copper cylinders are partly filled with acetone, and acety-
lene pumped in until a certain pressure is obtained. By
attaching one of these tanks to a lamp, a strong light
may be maintained for many hours. The rationale of
the process is that acetone dissolves acetylene under
pressure and slowly gives it up when the tension is re-
leased.

Naphtha or Gasoline Gas. — Many isolated country
houses depend for heat and light on this mixture. Out-

84 HOUSEHOLD CHEMISTRY

side of the building and underground, is placed an iron
tank for holding the hydrocarbon ; pipes lead to and from
the house. In the house cellar is placed a large revolving
drum driven by weights, for forcing air through the
gasoline and driving back to the house the vapor-laden
air. The process is satisfactory on a small scale but
rather expensive, depending wholly on the price of the
hydrocarbon.

Blau gas is the invention of a German chemist, Her-
man Blau. It is a mixture of hydrocarbons which are
gases under ordinary conditions, but which liquefy under
high pressures and low temperatures and are reconverted
into gases when the pressure is released. In the making
of Blau gas ordinary gas oil is distilled in retorts, the
mixture of gases produced is purified, cooled and com-
pressed up to 100 atmospheres. Hydrocarbons which
liquefy under these conditions will absorb others which
do not, and also so-called permanent gases such as
methane and hydrogen. The liquefied gas is delivered
for use in steel cylinders under high pressure, with a
device attached for reducing the pressure before the gas
enters the service pipes. One cubic foot of the liquefied
substance expands to 400 cubic feet of gas.

Pintsch Gas. — A similar method of compressing gas
was invented by Pintsch. Under his system the oil is
distilled at about 1,000°, in order to produce a large
amount of fixed gases. About 80 cubic feet of gas is
obtained from I gallon of oil. These gases are stored
in receivers under a pressure ordinarily of 6 atmos-

HOUSEHOLD CHEMISTRY 85

pheres. Pintsch gas is widely used for lighting railway
cars, the receivers being carried underneath the car.

EXPERIMENTS.

Preparation of Methane.— In a hard glass 8-inch test tube place
a mixture of 6 grams of fused sodium acetate and 4 grams of
soda lime. Close with a cork bearing a glass exit tube. Heat
strongly and light the methane gas at the mouth of the tube.
Complete the equation:

CH3COONa + NaOH ~-*

Preparation of Ethylene.— To 10 cc. of H2O in a beaker slowly
add 30 cc. of concentrated H2SO4 and cool. Put this mixture
in an Erlenmeyer flask, fitted with a separatory funnel contain-
ing 14 cc. of C2H5OH, and a delivery tube. Add clean sand to
the flask to prevent bumping. Carry the delivery tube through
the cork of a clean, dry, 12 or i6-ounce bottle. Pass another
delivery tube out of the bottle and carry to a pan for collecting
gas over water. Slowly drop the alcohol into the flask, heat
gently, and collect i wide-mouth bottle and 2 narrow-necked
bottles of the resulting gas. Test the gas in the wide-mouth
bottle for inflammability. Write the reactions for the prepara-
tion of the gas and its combustion.

Into one of the narrow-necked bottles place I cc. of bromine
water, close the bottle and shake. Explain, note odor, and write
reaction. Into the second bottle put a very dilute solution of
K2Mn2O8 and add I cc. of 10 per cent. Na2CO3. Close and shake.
Note the change. Look up von Baeyer's reaction for the double
bond.

Preparation of Acetylene.— i. Drop a very small lump of cal-
cium carbide into a test tube half full of water. Light the gas
evolved and note its illuminating quality.

2. Put 10 grams of calcium carbide in an Erlenmeyer flask
provided with a separatory funnel and a delivery tube. Add
water drop by drop through the funnel and collect the gas
evolved over water, in small bottles or cylinders. Observe its

86 HOUSEHOLD CHEMISTRY

inflammability (Caution: acetylene mixed with air is explosive),
its odor, and solubility in water and alcohol. Test with bromine
water and K2Mn2O8 as under ethylene. Write reactions.

3. Collect some illuminating gas in bottles containing bromine
water and KjMn2O8 respectively, as under ethylene, and shake.
Note results. What does this show with regard to certain con-
stituents of the gas?

CHAPTER VII.

CARBOHYDRATES.

Carbohydrates are valuable organic compounds repre-
senting one of the food principles. They originate chiefly
in the development of vegetable life, being built up in
the cells of all chlorophyll-bearing plants. These com-
pounds contain the elements carbon, hydrogen and
oxygen, and with some exceptions are aldehyde or ketone
alcohols. The term carbohydrate, signifying carbon,
with hydrogen and oxygen in the proportion to form
water, has lost its significance, for although important
members of the group conform to this arrangement, e. g.f
sucrose (GltHMOM), glucose (C6H12O6) and starch
n(C6H10O5), carbohydrate bodies are known which do
not. Furthermore, acetic and lactic acids which are not
carbohydrates have respective formulas of C2H4O2 and
C3H6O3. A better general term is saccharids or saccha-
roses. The usual classification subdivides the saccharids
as follows:

Monosaccharids. — Sugars which do not hydrolyze to
simpler saccharids. They are polyhydric alcohols joined
with an aldehyde or a ketone group, and in consequence
are called either aldoses or ketoses. The number of car-
bon atoms in the molecule is indicated by the terms
tetrose, pentose, hexose, etc., and the full description may
be, for example, aldohexose, or ketohexose. The hexoses
are the most important members of this group.

Disaccharids. — The disaccharids yield two monosac-
charid molecules of the hexose type on hydrolysis.

88 HOUSEHOLD CHEMISTRY

Trisaccharids. — Raffinose, the most important example,
hydrolyzes to three hexoses.

Polysaccharids. — These bodies have large complex
molecules which hydrolyze to an unknown number of
monosaccharid molecules.

The more important carbohydrates are classified in
detail below :

Classification and Occurrence,—

MONOSACCHARIDS.

Pentoses, C5H10O5. Arabinose, Xylose, etc.

These do not occur free in nature, but result
from the hydrolysis of polysaccharids called
pentosans. (See page 91.)
Hexoses, C6H12O6.

Glucose or dextrose. Sometimes called grape
sugar. Occurs in large amounts in grapes, is
widely distributed in other fruits and plants,
and is a product of the hydrolysis of most of
the di-, tri-, and polysaccharids. Normal blood
contains a small quantity, which is greatly in-
creased in diabetes.

Fructose or levulose. Sometimes called fruit
sugar. Associated with glucose in nature, is a
large constituent of honey, and is also a product
of hydrolysis of some carbohydrates.

Galactose. Has no common name and is not
found free in nature. It is obtained by the hy-
drolysis of lactose, rafrinose, and the galactans.

HOUSEHOLD CHEMISTRY 89

DlSACCHARIDS.

The important disaccharids have the formula
C12HMOn. They are :

Sucrose. Known as cane, beet or maple
sugar, and found with glucose and fructose in
the juice of many other plants. ,

Maltose. The malt sugar of germinating
grains. Also a product commercially of the
partial hydrolysis of starch.

Lactose. Known as milk sugar and found in
the milk of most mammals.

TRISACCHARID.

Raffinose, C18H32O16. Found in the germ of wheat
and barley, in cotton seed, and usually in the sugar
beet. It is commonly extracted from beet molasses.

POLYSACCHARIDS.

The general expression wC6H10O5, n signifying that
the molecule is an indefinite multiple of the for-
mula given, is assigned to the hexosans of this
complex group. Principal members are :

Starch. The most important and widely dis-
tributed polysaccharid. It occurs in plants gen-
erally, especially in roots, tubers and seeds.

Dextrin. Formed from starch by the action
of heat alone, or by partial hydrolysis with
enzymes or acids. Found in germinating cereals
as a transition product.

9O HOUSEHOLD CHEMISTRY

Glycogen Sometirnes called animal starch.
It is seldom found in plants, except in certain
fungi and in varying amounts in yeast. It
occurs in large quantities in the liver of animals
and in the muscle of the scallop, and in smaller
proportion in the blood and muscles generally.

Cellulose. Constitutes the framework of the
cell walls of all plant tissues. The cotton fiber
is nearly pure cellulose.

Inulin. A starch-like body extracted prin-
cipally from dahlia tubers, but found also in the
artichoke and the roots of chicory.

Galactans. Occur in the seeds of legumes;
yield galactose on hydrolysis.

Pentosans. (C5H8OJ«. Araban and xylan.
yielding arabinose and xylose on hydrolysis.
Widely distributed in nature, especially in such
substances as bran, wood, straw, etc. No con-
siderable amount in food material.

Natural Gums. Bodies which are generally
classed with the polysaccharids, but the com-
position of many of which is not definitely
known. Pectin bodies belong to this group.

Photosynthesis. — Light is an important chemical agent
in the synthesis of carbohydrates. In the presence of
sunlight the chlorophyll-bearing plant cell takes carbon
dioxide from the air, combines it with water, and poly-
merizes the product into a carbohydrate body. This

HOUSEHOLD CHEMISTRY 91

photosynthesis may be represented by :

6CO, + 6H,0 ~ C6H1206 + 602.

Such an expression does not take into account the inter-
mediate products of the synthesis. Chlorophyll itself
may undergo oxidation, yielding a chromogen body and
two alcohols. One of these alcohols, phytol, oxidizes to
formaldehyde, and this may be synthesized to a mono-
saccharid, according to the reactions :

CO2 + H2O — HCHO + O2,
6HCHO — C6H12O6.

Hydrolysis. — By enzyme action in the plant or animal
body, or by the action of dilute acids and heat, di- and
polysaccharids are hydrolyzed. The hydrolysis of a few
of the important saccharids is given:

Enzymes. Products.

C Equal parts of

Sucrose sucrase or invertase x glucose and fructose

I (invert sugar).

Two molecules of

? glucose.

{Equal parts of
glucose and galac-
tose.

Starch amylases C Dextrins and

Glycogen (ptyalin diastase -I maltose,

etc.) I

Raffinose is hydrolyzed by strong mineral acids to a
molecule each of glucose, fructose, and galactose. Inulin
is easily changed by acid hydrolysis to fructose ; it is not
ordinarily attacked by enzymes. Cellulose and starch are
considered anhydrides of glucose, and both yield glucose
on acid hydrolysis. Ordinary cellulose is not, however,
7

Q2 HOUSEHOLD CHEMISTRY

hydrolyzed by amylases or other enzymes, but by bac-
terial action.

The hydrolysis of pectic bodies is complex, and the
cleavage products not definitely known. A substance is
found associated with cellulose in the cell walls of unripe
fruits to which the name pectose is given. As the fruit
ripens, pectose is converted by enzyme action into pectin.
This change can be brought about by boiling pectose with
dilute acids or caustic alkalies, and the products include
not only pectin in several forms but a number of acids.
Pectin has the power of swelling in water and gelatiniz-
ing, a property of which advantage is taken in jelly
making. (See Chap. VIII.)

In household practice many examples of hydrolysis
occur, e. g., when starch and sugar are cooked with fruit
acids ; in the process of caramelizing sugar or in making
fondant. Sugar hydrolyzes much more quickly than
starch.

Optical Activity. — Nearly all carbohydrates are optic-
ally active. Pure sucrose has a right rotation of 66° ;
its hydrolytic products, glucose and fructose, show muta-
rotation, but the average figure for dextro-glucose is
-(-52.5°, that for fructose or levulose is — 93-8°. Since
the pull of fructose to the left is greater by 41.3° than
that of glucose to the right, it can be seen that an equal
mixture of the two would have a left rotation, opposite
to that of sucrose. For this reason the name invert
sugar is given to the hydrolytic products of sucrose. A
practical application of optical activity is made in the use

HOUSEHOLD CHEMISTRY 93

of the saccharimeter (q. v.), by means of which the
purity of sugar solutions is determined by estimating the
amount of sucrose present.

Solubility. — The mono- and disaccharids are soluble in
water. Of the polysaccharids, starch is not soluble in
cold water, but in hot water the granules burst and the
contents become a gelatinous mass known as starch
paste. Dextrin is soluble in cold water, more readily in
hot; glycogen dissolves with an opalescent appearance;
cellulose is not soluble in either hot or cold water. In
strong alcohol the monosaccharids are sparingly soluble;
of the disaccharids maltose dissolves most readily, sucrose
to a limited extent, lactose is almost insoluble. All the
polysaccharids are insoluble.

General Reactions. — Molisch's Test. — All soluble car-
bohydrates respond to Molisch's reagent. To about 3 cc.
of a dilute solution of any carbohydrate add 2 or 3 drops
of Molisch's reagent, mix thoroughly, and carefully pour
concentrated H2SO4 down the inclined side of the test
tube. A violet ring appears at the con-tact surface of the
liquids.

Furfural. — All carbohydrates yield some furfural on
treatment with boiling HC1; the pentoses are distin-
guished by the formation of large amounts.

Ultimate Composition of a Typical Carbohydrate. — Place half
a teaspoonful of dry granulated sugar in a clean, dry 6-inch test
tube. Heat gently in a Bunsen burner, observe the browning of
the contents and the collection of moisture in the upper part of
the tube. Explain. Increase the heat until dense fumes arise
and then bring a flame to the mouth of the tube. What happens ?

94 HOUSEHOLD CHEMISTRY

What are the fumes? Continue the heating until no more vola-
tile products are given off, then cool the tube and remove some
of the residue. What is it? Does it leave any residue on igni-
tion? From the results of this experiment, what conclusions
can be drawn as to the composition of sugar?

Glucose.

Preparation. — Glucose is prepared commercially in the
United States by hydrolyzing starch with very dilute hy-
drochloric acid under pressure, neutralizing with soda
ash, and evaporating the product in vacuo. It is sold
in syrup and in crystal form. Commercial glucose con-
tains varying amounts of dextrin. By carrying the hy-
drolytic action further, pure glucose or grape sugar may
be produced.

Constitutional Structure. — That glucose is an aldo-
hexose is proved by its reactions. The structural for-
mula usually assigned to it is CH2OH(CHOH)4CHO.
The space configuration shown below illustrates the
isomeric differences between glucose and the other im-
portant hexoses:

CH2OH CH2OH CH2OH

OH— |— H OH H OH— |— H

OH— I— H OH H OH H

H— |— OH H— |— OH H— |— OH

OH— |— H H— |— OH CO

CHO CHO CH2OH

glucose galactose fructose

The most commonly occurring form of glucose rotates
the plane of polarization to the right 52.5°.

HOUSEHOLD CHEMISTRY 95

Properties. — Glucose is crystalline, soluble and diffu-
sible. It crystallizes with difficulty from water, more
readily from alcohol. In the first case the crystals ap-
pear as thin plates in amorphous masses, usually contain-
ing water of crystallization. Anhydrous needle or prism
crystals may be obtained from alcohol.

Nearly all yeasts readily ferment glucose, producing
for the most part alcohol and carbon dioxide: C6H12O6
— » 2CO2 + 2C2H5OH.

Reducing Power. — Glucose shows its aldehyde charac-
ter in its power of reducing metallic solutions such as
are found in Fehling's, Barfoed's or Nylander's reagents,
or alkaline silver nitrate. In the last a silver mirror
is formed ; in Fehling's and Barfoed's the reduction from
a higher to a lower copper oxide is shown by a color
change from blue to red. Fehling's solution is the one
most commonly used to determine the presence of a re-
ducing sugar. The reactions taking place in changing
from the cupric hydroxide to the cuprous oxide may be
briefly indicated as follows :

2Cu(OH)a ~-+ 2CuOH -t H2O + O.
Blue Yellow

2CuOH — Cu2O + H2O.

Red

The reduction of Fehling's by glucose may be made
quantitative, 50 milligrams of glucose reducing 10 cc.
of the standard solution. The following reaction in-
dicates the possible oxidation of the glucose :

C6H12O6 + 6Cu(OH)2 ~- CH3CHOHCOOH +

COOHCHOHCOOH + 3Cu2O + 7H,O.

96 HOUSEHOLD CHEMISTRY

Formation of Osazone. — With phenylhydrazine glucose
forms yellow needle crystals of phenylglucosazone, which
are an identification test for this sugar. The change
involves several reactions, in the first of which a hydra-
zone is formed:

CH2OH(CHOH)4CHO + NH2NHC6H5 ~-

Glucose Phenylhydrazine

CH2OH(CHOH)4CH:N.NHC6H5 + H2O.

A second reaction takes place, more phenylhydrazine
acting as an oxidizing agent on the adjacent = CHOH
group:

= CHOH + NHSNHC6H6 «~

= CO + NH3 + NH2C6H5.

The CO left forms a second hydrazone group with phen-
ylhydrazine present, the product being called an osazone,
in this case phenylglucosazone :

CH2OH(CHOH)SCOCHNNHC6H5 + NH2NHC6H5 —
CH2OH ( CHOH)3C : N. NH€6H5CH :N. NHC6H5.

Action of Acids and Alkalies. — When boiled with strong
HC1, glucose is oxidized to levulinic acid, CH3COCH2
CH2COOH; with nitric, to saccharic acid COOH
(CHOH)4COOH. If heated with strong caustic soda
or potash a series of complex reactions of an oxidative
nature take place, and a brown color results. All car-
bohydrates with a free carbonyl group give this reaction.

EXPERIMENTS ON GLUCOSE.

I. Taste, and note the sweetness. (Glucose is about three-
fifths as sweet as cane sugar.) Roughly determine its solubility
in hot and cold water and in alcohol. Does it react with iodine?

HOUSEHOLD CHEMISTRY 97

2. Effect of Heat.— Heat some dry glucose in a clean dry test
tube; note the result.

3. Effect of Strong Acid. — To some dry glucose in a porcelain
dish add cold concentrated sulphuric acid ; note the result. After
allowing the test to stand for 5 minutes, heat gently and again
note the result.

4 Effect of Strong Alkali. — To some glucose solution add
strong caustic soda or potash and heat; note the result.

5. Crystallization. — Make a syrupy solution of glucose and
allow it to stand for several days. Do any crystals form?

6. Fermentation. — Combine equal portions of compressed yeast
with solutions of glucose, lactose, maltose and sucrose of equal
strength, and starch paste. Fill the long arm of five bulb fer-
mentation tubes with the five mixtures and close the bulb with a
cotton plug. Stand in a warm place until fermentation begins.
In each case note the rapidity with which carbon dioxide rises
in the long arm of the tube and presses the liquid into the bulb,
and draw conclusions as to the comparative action of yeast on
the four sugars and the starch. Examine the liquid in the bulb
for alcohol by (i) taste, and (2) heating with a small amount
of iodine and sodium carbonate solution.

7. Fehling's Solution Test.— Into a 100 cc. flask put 5 cc. of
copper sulphate solution and 5 cc. of alkaline Rochelle salts, mix
and add 20 cc. of distilled water, cover with a watch crystal and
boil for 2 minutes. No change should take place. Add a few cc.
of a i per cent, glucose solution, boil vigorously for 2 minutes,
cool and note the result. Continue adding glucose and boiling
until on cooling the blue color of the solution has faded. (50
milligrams of glucose are required.)

NOTE. — If acid, the solution under test must be neutralized, as
acids destroy the necessary alkaline condition of Fehling's and
act in some degree as reducing agents.

8. Barfoed's Solution. — Add a few drops of glucose solution
to a small amount of Barfoed's in a test tube; place the tube in
boiling water for not more than 5 minutes. A clear red precipi-

98 HOUSEHOLD CHEMISTRY

tate appearing around the edges of the liquid indicates reduction
to cuprous oxide. Barfoed's is an acid preparation — the test
solution added to it must be neutral.

9. Silver Mirror Test—To illustrate the reducing action of
glucose on silver nitrate make a silver mirror as follows : Clean
the article to be silvered — either a watch crystal or a small test
tube — with nitric acid, water, and strong alcohol in the order
mentioned, and place in contact with hot water. Take sufficient
5 per cent. AgNO3 to fill the article, add ammonia cautiously
until the precipitate formed almost disappears on shaking, then
I or 2 cc. of a weak glucose solution. Mix quickly and fill the
glass receptacle. When the reduction to metallic silver seems
complete, pour off the solution.

10. Preparation of Phenylglucosazone. — To 0.2 gram of pure
glucose dissolved in 4 cc. of water, add 0.4 gram of phenyl-
hydrazine hydrochloride, and 0.6 gram of crystallized sodium
acetate. Filter the solution if not clear, close the test tube with
a cotton plug, warm in a water bath until yellow crystals of
phenylglucosazone appear. Observe these under a microscope.

Grlucosides. — These are complex substances found in
the vegetable kingdom, which on hydrolysis yield a car-
bohydrate — generally glucose — and one or more other
compounds. Many glucosides are known, together with
the hydrolyzing enzymes which usually accompany them
in the plant. A well-known example is amygdalin, found
in bitter almonds, and the kernels of peaches, cherries,
plums, etc. It is hydrolyzed by the emulsin of almonds
to glucose, benzaldehyde, and hydrocyanic acid. An-
other example is phloridzin, found in the root bark -of
apple, pear, plum and cherry trees, yielding glucose and
phloretin by acid hydrolysis.

HOUSEHOLD CHEMISTRY 99

Fructose.

The occurrence of fructose or levulose in nature has
been given, also its space configuration (pp. 88 and 94.)
The form of fructose found in nature rotates the plane
of polarization to the left 93.8°.

Fructose is harder to crystallize than glucose, but
forms fine rhombic needles. It is somewhat sweeter than
cane sugar.

Reactions. — i. Resorcin gives a characteristic color
reaction with fructose, due to the ketohexose nature of
the latter. Carbohydrates such as cane sugar which
yield fructose on hydrolysis, also give this reaction.

Mix equal volumes of hydrochloric acid and fructose solution
and add a few drops of resorcin solution. Warm ; notice a deep
red color and the formation of a brownish precipitate.

2. Substances which, like fructose, have a ketone rad-
icle linked to a = CHOH group, act as reducing agents
in alkaline solutions such as Fehling's.

3. Milk of lime precipitates fructose as an insoluble
calcium compound, and thus can be used to separate the
constituents of invert sugar, since the glucose compound
remains in solution.

EXPERIMENT.

Dissolve 50 grams of pure honey in 250 cc. of water, cool
with ice, and add 30 grams of slaked lime in small quantities,
stirring constantly. Filter off the precipitate, wash it with a
little water, press strongly to remove excess liquid, suspend it in
water, and pass a stream of carbon dioxide through the mixture.
The lime compound of fructose is decomposed. What precipi-
tates? Filter and evaporate the fructose in the filtrate to a
syrup. Test with Fehling's and resorcin.

100 HOUSEHOLD CHEMISTRY

If invert sugar is used for the above experiment decrease the
amount to 10 grams.

4. With phenylhydrazine fructose gives an osazone
identical with phenylglucosazone.

Fructose may be obtained by extracting inulin from
dahlia tubers and hydrolyzing.

EXPERIMENT.

Wash and grate several dahlia tubers; suspend the gratings in
water. After standing, skim off and reject the floating mass.
Mix the sediment of inulin with fresh water and when settled
siphon off the liquid. The operation of washing should be
repeated. Finally add more water and heat on a water bath for
an hour, with a few drops of HzSO* as the hydrolyzing agent.
Neutralize with barium hydroxide, filter, and evaporate the
filtrate at low heat to a syrup. Apply tests given above for
fructose.

Galactose.

Galactose is an aldose, which is not found in the free
state, but can be prepared by hydrolyzing lactose and
separating the products, glucose and galactose, by crys-
tallization of the latter from aqueous alcohol. It crys-
tallizes in prisms which melt at 168°. Galactose is
mutarotatory, with an equilibrium value of +81°. With
phenylhydrazine it forms a compound similar to glucose.
Galactose is fermentable, but not by ordinary yeast.

Sucrose.

Sucrose is an alcohol, with no free aldehyde or ketone
group, as is shown by its formula :

HOUSEHOLD CHEMISTRY IOI

CH2OH CH2OH

1 1

CHOH . CH

|

1

r- CH

CHOH

0 |

CHOH

CHOH

3 1

1

CHOH i — C

| /I

PTT O/ OH OH

It therefore does not act as a reducing agent when pure.
Chemically, it is identical whether produced from cane,
beets, or maple sap. It crystallizes easily in large octa-
hedrons, and is the most readily soluble in water of all
the carbohydrates. In strong alcohol it is scarcely solu-
ble. Sucrose hydrolyzes readily with sucrase and dilute
acids; even heat alone is effective. In the last case the
product is called caramel, and the beginning of the inver-
sion corresponds with the first yellowing of the sugar.

Glucose Fructose
C,,HM0U + H,0 — C.H.,0. + C6H120S.

Saccharimeter Test. — The purity of cane sugar, i. e., its
freedom from invert, is determined with a modification
of the polariscope called a saccharimeter. In one type of
the instrument, using the Ventzke scale, the light passes
through the polarizer, to the tube containing the sugar
solution, and then through the analyzer. Behind this is a
pair of quartz wedges arranged to neutralize the rotating
effect of the sugar, and at the same time record the per-
centage of rotation on a scale. The rotating effect of

102 HOUSEHOLD CHEMISTRY

pure sugar, + 66°, is read as 100 per cent, on the scale.
Any lesser figure indicates the percentage of sucrose
present.

For the saccharimeter test (using the Ventzke scale)
26 grams of cane sugar are dissolved in the least quantity
of water and made up to 100 cc. The solution must be
clear and colorless. In case it is not, the cloudiness may
be removed by means of a solution of basic acetate of
lead, which precipitates dextrin and gummy matter. The
operation is conducted as follows: 26 grams of the
sugar are dissolved in 60-80 cc. of distilled water, a few
cc. (not more than five) of the lead solution are added
drop by drop as long as a precipitate appears, then double
the quantity of alumina cream and enough distilled water
to reach the 100 cc. mark. The mixture is shaken vigor-
ously and allowed to stand for a few minutes for the
bulky precipitate to settle. It is then filtered through dry
paper, the first 20 cc. of the filtrate being rejected. The
tube of the instrument is filled with the solution, the
rotating effect determined, and the percentage of purity
read on the scale.

EXPERIMENTS ON SUCROSE.

1. Roughly determine its solubility in cold and hot water, and
in alcohol. Is the solubility affected by heat?

2. Crystallization. — Make a hot syrupy solution of sugar and
suspend in it a piece of glass rod by a thread. Set aside and
allow to cool and after a time carefully examine the crystals of
cane sugar.

3. Effect of Dry Heat. — Boil down sugar solution to dryness
and note the result.

4. Effect of Strong Acid. — Drop some concentrated sulphuric

HOUSEHOLD CHEMISTRY IO3

acid on dry sugar, note the result and compare with starch and
glucose.

5. Add a weak sugar solution to boiling Fehling's reagent. If
pure there should be no reduction.

6. Hydrolysis— "Inversion."— Add a few drops of concentrated
hydrochloric acid to a dilute sugar solution, and heat over boil-
ing water for 15 minutes. Cool, neutralize with sodium car-
bonate and add to Fehling's solution; note the result and com-
pare with glucose. What change has taken place?

7. Test hydrolyzed and unhydrolyzed sugar solution with
Barfoed's.

8. Effect of Strong Alkali.— To 10 cc. of a weak sugar solution
add some strong caustic soda, heat and note the result; compare
with glucose.

9. Specific Test.— To 15 cc. of the clear liquid, add 5 cc. of
cobalt chloride (5 per cent.) and 2 cc. of caustic soda (50 per
cent.). Sucrose gives an amethyst-violet, permanent on heating.
Glucose gives a turquoise-blue, turning to green on standing
some time, or on gentle heating. This test may be used on con-
densed milk, honey, preserves, etc.

10. Caramel Test. — Boil a strong solution of sugar until it has
turned brown (caramel), cool, dilute and test some of the liquid
with Fehling's solution.

11. Saccharimeter Test.— Determine the purity of samples of
cane sugar by the saccharimeter.

12. Formation of Sucrosate.— Sucrose unites with metallic
hydroxides such as calcium and barium to form sucrosates. Cal-
cium sucrosate may be prepared by saturating milk of lime with
sucrose at low heat. The product is commonly called viscogen,
and is used as a thickener in whipping cream, etc. See p. 232.

13. Resorcin Test. — To a solution of cane sugar add an equal
volume of HC1 and a few crystals of resorcin. Warm. A deep
red color appears, due to the formation of fructose.

Maltose.
Maltose does not occur in nature, but is produced

104

HOUSEHOLD CHEMISTRY

during the hydrolysis of starch by unorganized ferments,
such as ptyalin and diastase. It is an aldose, as is shown
by its formula :

CH2OH

I
CHOH

I
— CH

CHOH

O

CHOH

I

— CH-

-CH,

CHOH

6 CHOH
I
CHOH

CHOH

I
CHO

On hydrolysis, by maltase or dilute acids, maltose yields
two molecules of glucose:

Glucose
C^O,, + H,0 ~ aq.H.,0..

Maltose like lactose contains a free carbonyl group
and hence reduces Fehling's solution directly — 80 milli-
grams reduces 10 cc. of the reagent.

Maltose is readily soluble in water and crystallizes
from it in fine plates in the hydrated form C12H22On,
H2O. It becomes anhydrous by drying at 100°. In the
hydrated state it dissolves more freely in alcohol than do
sucrose and lactose, and in this way also can be separated
from its mixture with most dextrins, which are precip-
itated by alcohol of over 60 per cent, strength. Maltose
crystallizes from alcohol in the anhydrous state.

With phenylhydrazine, yellow crystals of phenylmalt-

HOUSEHOLD CHEMISTRY IO5

osazone form which resemble irregular daisy petals or
knife blades.

EXPERIMENTS ON MALTOSE.

Preparation of Diastase in the Form of Malt. — Malt is pro-
duced during the germination of barley and other cereals. Pre-
pare it as follows : Spread out a thin layer of barley grains
(one tablespoonful) on the cover of a small pasteboard box,
moisten with warm water and keep in a moderately warm place.
Each grain will soon begin to sprout. When the acrospire has
grown the length of the grain, dry the mass in an oven at a low
temperature and keep bottled. Make malt extract by grinding
the grains coarsely and extracting them with 100 cc. of warm
water. Note the taste and odor of the liquid. Keep for future
use.

Preparation of Pure Maltose. — Make a thin paste of starch
and boiling water, cool to 65° and add 10 cc. of malt extract,
prepared as above, and continue the heating at 65° for half an
hour. From time to time test small portions of the liquid with
iodine solution. When the liquid fails to react blue, cool the
balance of the solution, divide in 6 parts and test as follows:

1. Solubility in Alcohol. — Add some of the liquid to strong
alcohol, allow to stand and note the white precipitate of dextrin;
the liquid contains maltose.

2. Effect of Fehling's Solution. — To 10 cc. of Fehling's solution
add a few drops of the liquid, boil for 2 minutes and note the
reduction; add more of the solution and boil again; repeat until
the reduction is complete.

3. Test with Barfoed's reagent.

4. Apply the fermentation test.

5. Test with strong caustic soda or potash.

6. Repeat the phenylhydrazine test. Compare with glucose.
NOTE. — The above tests may be made on commercially pre-
pared maltose.

IO6 HOUSEHOLD CHEMISTRY

Lactose.

Lactose, or milk sugar, is a disaccharid containing a
free carbonyl group. The structural formula for maltose
(q. v.) may be used to represent lactose also. It is a
reducing agent, 67.8 milligrams being required to reduce
completely 10 cc. of Fehling's.

Lactose is less soluble in water than sucrose or maltose.
Five or six parts of cold water are required for solution,
or about two and one-half parts of boiling water. When
crystallized from water at low temperature it contains
one molecule of water of crystallization, which is lost by
heating the crystals to 130°. Lactose is insoluble in
alcohol.

With phenylhydrazine yellow crystals of phenyl-lact-
osazone are formed, which resemble chestnut burrs.
Ordinary yeast does not ferment lactose, but lactic fer-
ments convert it into lactic acid and alcohol. Lactose
readily undergoes butyric acid fermentation.

By hydrolysis with lactase or dilute acids lactose is
converted into a molecule each of glucose and galactose.

Glucose Galactose
C12H22On + H20 -~ C6H1206 + C6H1206.

EXPERIMENTS ON LACTOSE.

Preparation.— Allow milk to stand until well soured; filter.
Faintly acidulate the whey with dilute acetic acid and heat to
coagulate protein material. Filter, and evaporate the nitrate
over hot water to crystallization. The crystals are crude lactose.

Take some of the lactose so prepared, or the commercial form,
and make the following tests:

i. Note the hardness and slightly sweet taste, due to the
limited solubility.

HOUSEHOLD CHEMISTRY IO/

2. Try its solubility in water and in alcohol.

3. Treat some dry powdered lactose with concentrated sul-
phuric acid; note the result.

4. Try the caustic soda reaction.

5. Apply the Fehling's test.

6. Test with Barfoed's reagent.

7. Make a weak solution of lactose in water, let it stand at
least 24 hours in a moderately warm place, and then test for
acidity.

8. Make the phenylhydrazine test, compare with glucose and
maltose.

Starch.

Starch is the most widely distributed carbohydrate.
It is found in varying proportions in leaves, stems,
woody tissues, roots, tubers, fruits and seeds, but is es-
pecially abundant in the cereal grains and in tubers such
as the potato. The formula n(C6H10O5) is used to
express its large and complex molecule, but soluble starch
— or its principal constituent, amylo-dextrin — is some-
times represented as (C12H20O10)54.

Physical State. — Pure starch is a white, powdery sub-
stance, colloidal and granular. The granules are definite
in average size and appearance according to their source.
Potato starch has one of the largest granules. They
are ovoid in shape, and show concentric layers which in-
crease in thickness with their distance from the nucleus
or hilum. The size increases with age. As a general
rule the large granules are more easily disrupted by heat.
The outer layer of starch granules is known as starch cel-
lulose ; the contents as granulose or amylose.

Effect of Heat. — In hot water the outer layer of starch
granules is ruptured and the contents gelatinize, form-
8

108 HOUSEHOLD CHEMISTRY

ing a partial solution known as starch paste. The tem-
perature of gelatinization varies from 65° to 85°, ac-
cording to the kind of starch. Root and tuber starches
gelatinize at a lower temperature, as a rule, than cereal
starches. According to some investigators1 gelatinization
is caused by a mucilaginous substance, amylo-pectin,
found in the granule. This body gives a purplish blue
with iodine, and swells without dissolving in hot water.

Ordinary air-dried starches dextrinized at temperatures
from 160° to 210°. Reducing sugars may possibly be
formed. With higher temperatures, and out of contact
with air, starch yields products similar to those formed
in the dry distillation of wood.

Effect of Low Temperature. — On cooling, starch paste
contracts. Its greatest contraction is at freezing point,
when a permanent separation of water and starch takes
place to a considerable extent, and the starch dries out
as a powdery mass. This substance is often noticed on
starched clothes dried after being frozen, and such
clothes have lost most of their stiffness.

Soluble Starch. — Starch is manufactured in several
grades with regard to thickening quality. With long
continued heating or heating under pressure at 130°- 150°,
with ten times its weight of water, a form of starch is
prepared which goes into true solution. It does not
gelatinize, but gives the iodine reaction and does not
reduce Fehling's.

Reaction with Iodine. — This is the most characteristic
test for starch. A deep blue color is produced whether

1Maquenne and Roux : Ann. Chim. Phys., 1906 [8], 9, 179.
Matthews and Lott: /. Inst. Brewing, 1911, 17, 219-266.

HOUSEHOLD CHEMISTRY 1 09

the granule is ruptured or not. The compound formed
is called starch iodide.

Action of Acids and Alkalies. — On boiling with dilute
(2 per cent.) HOI or H2SO4, starch is hydrolyzed to
dextrins and maltose, and finally to glucose. Concen-
trated H2SO4, causes a complete carbonization of air-dry
starch in a short time. Strong HC1 on dry starch causes
a swelling of the granules and in a short time a change
to the soluble form. If the action is continued for a
few days, hydrolysis of the granules to achroodextrin,
maltose and glucose results, while the starch cellulose
remains unchanged. With nitric acid various products
are formed according to conditions. On boiling with
strong HNO3 (specific gravity 1.2) starch is converted
into oxalic acid. With cold concentrated HNO3 com-
pounds may be formed similar to the nitrates of cellulose.
In presence of cold strong fixed alkali, starch is solu-
ble with partial hydrolysis and usually the product has
a distinct yellow color; weaker solutions have very little
effect unless heated.

Action of Enzymes. — Amylases, whether the diastase of
grains, the ptyalin of the saliva, or the amylopsin of the
pancreatic secretion, hydrolyze starch to maltose. The
first reaction is a quick change of starch paste to soluble
starch. Shortly after, the blue color with iodine gives
place to a reddish brown, showing the presence of erythro-
dextrin. At the same time maltose is formed. The
change may be expressed as :

(C8HW05)« + HOH ~ C,2H,A, + (C.H.A)*.

maltose dextrin

IIO HOUSEHOLD CHEMISTRY

As the action continues an achroodextrin stage is reached
where the iodine ceases to act, and the amount of re-
ducing sugar is increased. According to Maquenne and
Roux, the maltose is produced from the principal con-
stituent of the granule, amylose, and the residual dextrin
comes from the amylo-pectin, which is slowly changed
by enzyme action, but does not yield a reducing sugar.
Experiments by these investigators and others show
about 80 per cent, of maltose formed after 2 hours of
diastatic action. Hydrolysis with diastase proceeds most
rapidly at a temperature of about 55°.

Fermentation. — Various organisms are known which
ferment starch to alcohol. With yeast there is no direct
fermentation ; if a diastatic enzyme is present in the
starch, hydrolysis to maltose may take place, in which
case the maltase in ordinary yeast carries the hydrolysis
to glucose. This in turn is converted by zymase to
various substances, chiefly carbon dioxide and alcohol.

EXPERIMENTS ON STARCH.

1. Occurrence of Starch. — Examine a thin section of potato
under the microscope. Make a careful drawing of the structure
of the cells and the granules within. Cover the section with a
thin glass and introduce a minute trace of iodine solution at the
edge of the cover glass. Note and make a colored (blue pencil)
diagram of the result.

2. Extraction of Starch.— Clean and peel one end of a small
potato, rub it on an ordinary grater, collect the gratings in a
beaker of cold water, strain, allow the cloudy liquid to stand
until starch settles. Pour off liquid and use the sediment for
the following tests :

3. Effect of Dry Heat.— Gently heat half an inch of dry starch
in a clean, dry test tube. Observe and explain condensed moist-

HOUSEHOLD CHEMISTRY III

ure in the cooler part of the tube. Increase the heat somewhat
and note the odor of the evolved vapor and the color of the
starch : What does it suggest ? Now heat strongly until only a
black residue remains. What is it?

4. Effect of Strong Acid.— To a small portion of dry starch
in a porcelain evaporating dish add a few drops of concentrated
sulphuric acid ; note the result and after a short time heat gently
and observe again.

5. Solubility. — Treat a small portion of finely pulverized dry
starch with cold water, filter a portion and examine the filtrate
for dissolved material, by evaporating to dryness, also by the
iodine test.

6. Starch Paste. — Boil the remainder of the starch and water
mixture. Filter some of the gelatinized product and test a por-
tion of the filtrate with iodine, and with alcohol. What per
cent, of the latter is required for precipitation?

7. Conditions for Iodine Tests. — To another portion of the
cooled filtrate add iodine solution, gently heat and allow to cool.
Note the result. Now boil for some time and cool ; the color
will not return. Why?

To some starch solution in a test tube add a small portion of
caustic soda and a few drops of iodine solution and note the
result. Repeat the experiment using dilute sulphuric acid instead
of NaOH.

Test the effect of glucose and tannic acid on iodide of starch.

8. Effect of Tannic Acid.— Add a solution of tannic acid to
some starch solution. Note the result, also any change effected
by heating.

9. Precipitation with Basic Lead Acetate. — Add a few drops of
basic lead acetate to some starch solution.

10. Starch a Colloidal Substance.— Partly fill a diffusion thimble
with thin starch paste, and stand it in a beaker of cold water.
After some time, test the water for starch with iodine. Does
this explain why starch is not lost through the cell walls of the
plant?

112 HOUSEHOLD CHEMISTRY

NOTE. — For the following experiments use a I per cent, starch
solution.

11. Acid Hydrolysis.— To 75 cc. of starch solution add 2 cc. of
strong hydrochloric acid and boil until clear, using a reflux con-
denser. At this point, a small quantity of the cooled liquid should
give no blue coloration with iodine. If this is not the case add
10 drops more of the same acid and boil some minutes longer,
or until a small portion gives no test with iodine. Neutralize
the remainder of the liquid with sodium carbonate solution, add
10 cc. to Fehling's solution and boil. If reduction does not take
place add more of the solution and reboil.

2. Mix about I gram of starch with 10 cc. of strong HC1 and
allow the mixture to stand for 15 minutes. Now pour off a
small portion and add an excess of cold water. A milky pre-
cipitate of soluble starch results. Filter this and test its solu-
bility in hot water. Allow the remainder of the acid mixture to
stand for several days, until the viscous mass becomes clear and
separates into 2 layers. The upper layer contains starch cellu-
lose. Remove and test with iodine. Neutralize the lower layer
and make the Fehling's test.

12. Enzyme Hydrolysis.— i. Take about 25 cc. of clear dilute
starch paste in a small beaker and add 2 or 3 cc. of undiluted
saliva which has been filtered through coarse filter paper.

Keep at body temperature and from time to time pour off
small portions and test with iodine solution, keeping each for
comparison. Note the gradual change from blue to red to yellow
and finally to colorless. When this stage is reached, add a small
portion of the material to Fehling's solution, bdil, and note
reduction due to maltose.

2. To 25 cc. of dilute starch paste add about 5 cc. of diastase
solution and keep at 55°. Test portions from time to time with
iodine until the test fails to give a color (maltose). At this
stage boil the remainder of the solution with about 25 drops of
dilute sulphuric acid for 10 minutes. Neutralize and test this
with Fehling's solution for glucose.

HOUSEHOLD CHEMISTRY 113

13. Mix 10 cc. of dilute starch solution with an equal volume
of alcohol (95 per cent.), add to the mixture a saturated solu-
tion of barium hydroxide as long as precipitation occurs. Filter
and wash the precipitate slightly. Test the nitrate with iodine.
Suspend the precipitate in water and pass a rapid current of
carbon dioxide through the mixture for several minutes. Filter
and test the liquid with iodine solution. Explain.

Dextrin.

The dextrins are colloidal compounds, soluble in water,
and precipitated by strong alcohol. As starch hydrolysis
proceeds a number of dextrins are formed: the dextrin
which gives a red-brown color with iodine is termed
erythrodextrin ; that which is forming as iodine ceases to
act is achroodextrin. A maltodextrin is known to which
the formula 6(C6H10O5)H2O has been assigned. It ap-
pears to be a chemical combination of one part maltose
and two parts dextrin, and is a reducing substance. Dex-
trins proper are not considered to have reducing power
when pure.

Dextrins are used to a great extent in textile and
other industries for sizings, as a medium for colors in
textile printing, as gum, paste, etc. They also form
about half the carbohydrate material in corn syrup.

Preparation. — Dextrin or "British Gum" is prepared
commercially by two methods : ( I ) Dry starch is heated
to 200° -250° over an oil bath, in a steam jacket, or other
device to insure the requisite temperature without char-
ring. The product is dark in color, but has good adhesive
quality. (2) The starch is moistened with nitric or hy-
drochloric acid, dried, and heated to 140°- 170°. The

114 HOUSEHOLD CHEMISTRY

result of this partial hydrolysis is a light colored dextrin
containing some sugar, and having, therefore, less ad-
hesive power. Dextrin may be prepared more con-
veniently by heating a strong starch paste with moder-
ately dilute sulphuric acid until clear, cooling and pre-
cipitating by adding to ethyl alcohol.

EXPERIMENTS ON DEXTRIN.

Solubility. — Compare the solubility of dextrin in cold water
and in boiling water.

To successive portions of cooled dextrin solution in test tubes
add:

1. Alcohol up to 60 per cent, by volume.

2. Iodine solution.

3. Caustic soda and iodine solutions.

4. Sulphuric acid and iodine solutions.

5. A few drops of basic acetate of lead with and without
ammonia. Note the result and compare with starch and glycogen.

6. To boiling Fehling's solution : if pure there will be no
reaction.

7. Tannic acid as under starch.

8. For the hydrolysis of dextrin by enzyme action, follow the
method given under starch.

Glycogen.

Glycogen is known as animal starch, since it appears
as the reserve carbohydrate in the developing cells of
animal organisms. It is present in the liver in consider-
able quantity ; to a less extent in blood, muscle and several
glands. Its formula is (C6H10O5)w. In appearance
glycogen is a white, amorphous powder. It is soluble
with opalescence in water, insoluble in strong alcohol, and

hydrolyzes as starch does with diastase or with acids.

Glycogen gives a brownish red color with iodine, does not

HOUSEHOLD CHEMISTRY 115

reduce Fehling's, and is not fermentable by yeast. It
may be extracted in considerable quantity from the large
muscle of the scallop, as follows :

Preparation. — Grind a mixture of scallops and sand in
a mortar, transfer to a beaker, add enough water to
cover the mass and boil. This dissolves the glycogen
and partially precipitates the proteins, which are now
completely precipitated by slightly cooling and adding
a few drops of acetic acid. Filter and add the filtrate to
alcohol (95 per cent.). Glycogen will come down as a
white precipitate. Allow to settle, decant the clear liquid,
and filter the residue.

Apply the following tests to the glycogen thus ob-
tained :

1. Solubility in water; look for opalescence.

2. Solubility in 10 per cent, sodium chloride solution.

3. Solubility in hydrochloric acid.

4. Solubility in caustic potash.

5. Reaction with iodine solution.

6. Reaction with basic lead acetate, without ammonia.

7. Boil a dilute solution of glycogen in a beaker for 15 minutes
with 2 cc. of dilute hydrochloric acid, neutralize with sodium
carbonate and test with Fehling's solution. What change has
taken place?

Celluloses.

These compounds, represented by the general formula
nC6H10O5, are at once the most complicated and stable
of the carbohydrates.

They may be roughly divided into the simple and
compound celluloses, the former unicellular in structure
and the latter multicellular.

Il6 HOUSEHOLD CHEMISTRY

Cotton, thistledown, and the internal fibrous network
of grains and vegetables are simple celluloses and occur
as ribbon-like bands with curled edges and a character-
istic corkscrew twist. These forms contain little protein,
gum, fat or mineral matter. Flax, grasses and woody
fiber are compound celluloses, occurring for the most part
as jointed rods or tubes, and are highly charged with pro-
tein, fat, gum and mineral matter. Cotton is the only
unicellular form of cellulose of industrial importance,
while the multicellular type has many representatives, i. e.,
linen, hemp, jute, ramie and a great variety of woods.

The treatment of cotton does not involve any exten-
sive chemical operations, but is chiefly confined to
mechanical manipulation. The compound celluloses on
the other hand require complex and prolonged chemical
or bacterial treatment before the fiber is ready for the
operations of spinning, weaving and dyeing. Woody
fiber is now generally used for the preparation of the
felted fabric known as paper. It is necessary in this case
to remove all impurities by chemical means, and to break
up the long fibers by grinding before the fabric can be
prepared.

General Properties of the Celluloses. — Celluloses are
insoluble in water hot or cold, and in weak acids or
alkalies. Strong acids and alkalies cause them to hydro-
lyze; in some cases soluble forms result by heating or
prolonged action in the cold, or by a combination of both
methods. Generally speaking, the action of acids is more
rapid. When partially hydrolyzed they are colored blue
in the presence of iodine. Nitric acid in concentrated

HOUSEHOLD CHEMISTRY 117

form converts cellulose into nitrates of varying composi-
tion, containing one to six nitric groups — the form de-
pending on the duration of the nitrating process. All of
these compounds are very unstable and dissociate into
water, carbon dioxide and nitrogen, when slightly heated ;
hence their use as explosives. Cellulose nitrates, unlike
cellulose, dissolve in ether, alcohol or acetone or mixtures
of these solvents (collodion) and on evaporation yield
transparent structureless films, used in medicine, photog-
raphy and for the preparation of artificial silk. Am-
moniacal cupric oxide (Schweitzer's Reagent) and con-
centrated zinc chloride dissolve simple cellulose on gentle
warming. Hydrocellulose precipitates from these solu-
tions on acidifying with acetic acid.

Lignocellulose (wood) yields oxalic acid on treatment
with nitric acid, and oxalate of potash on fusion with
caustic potash.

Cellulose fibers are characterized by high capillary
capacity and heat conductivity; hence their use for lamp
wicks, toweling and summer clothing. These properties,
however, may be much modified by tight twisting and
close weaving, as in the case of canvas.

While ordinary cellulose is considered an anhydride of
glucose, and hydrolyzes to glucose, a hemi-cellulose is
known which yields mannose, galactose, arabinose and
xylose on hydrolysis, but no glucose.

EXPERIMENTS ON CELLULOSE.

(a) Effect of Heat (Charring).— Heat a piece of fibrous
material in a clean dry test tube. Note the odor of the gases
evolved and test the vapor with blue litmus paper. Examine the
charred mass with a magnifier.

Il8 HOUSEHOLD CHEMISTRY

(b) Solubility in Water.— Try to dissolve some fibrous material
in water.

(c) Solubility in Zinc Chloride.— Dissolve some absorbent
cotton in acid zinc chloride solution (ZnCU dissolved in twice
its weight of concentrated HC1). Precipitate by dilution and
compare the result with the original substance.

(rf) Solubility in Schweitzer's Reagent. — Dissolve some absorb-
ent cotton in Schweitzer's reagent, add the resulting solution to
95 per cent, alcohol and compare the precipitate with the origi-
nal substance.

(e) Structure. — Examine carefully the structure of cotton and
linen fibers under a microscope.

(/) Crude Fiber.— Crude cellulose of wood, grains, etc., is
determined as follows:

Take I gram of the dried ground sample, boil with 100 cc.
of \Y\ per cent, sulphuric acid ,when cool strain through muslin.
Wash once with hot water. Scrape the residue from the muslin
and boil it with 100 cc. of 1^4 per cent, caustic soda. Strain
again through the same piece of muslin, wash with hot water,
then with alcohol, and finally with ether. Weigh the dried
residue.

Nitrating. — Treat a piece of filter paper or some absorbent
cotton with a cooled mixture of 20 cc. concentrated H2SO4 and
10 cc. concentrated HNO3. Keep the solution cool. Several
nitrates of cellulose may form. The hexa- and penta-nitrates
are the most prominent. The hexa-nitrate of cellulose is called
gun cotton. Wash the product in water and dry. Test its
inflammability, and its solubility in a mixture of 40 per cent,
alcohol and 60 per cent, ether. The clear solution is collodion.
Observe how a film of it hardens in the air. When pressed
through capillary tubes, filaments are produced, which are deni-
trated and further treated to form one class of artificial silk —
the nitra-cellulose or pyroxylin.

Mercerization. — Stretch some cheesecloth or muslin tightly over
a porcelain dish and immerse for 15 minutes in a 25 per cent.

HOUSEHOLD CHEMISTRY IIQ

solution of caustic soda, at a temperature of about 20°. An
alkali-cellulose forms, and the cloth appears semi-transparent.
Wash free from alkali, dry, and notice the appearance of the
mercerized cotton compared with the original material. Try
its reaction with iodine. The cotton has become cellulose hy-
drate, w(C«H1005)H20.

Methods of Distinguishing Cotton from Linen. — The

microscope is the one reliable means of differentiating
these fibers, since full-bleached linen and cotton are
practically identical in chemical composition. How-
ever, the following tests are helpful if a microscope is
not available :

Breaking and Burning Tests. — Unraveled threads of linen
fabrics are untwisted and broken by holding between the thumbs
and index fingers and pulling apart slowly and steadily. Linen
parts slowly, and with pointed ends ; cotton breaks suddenly with
tasseled ends. Burn a small tuft of each fiber and note the con-
dition of the fiber ends.

Sulphuric Acid Test. — Dip a piece of union toweling in con-
centrated H2SO4, for about iy2 minutes. Remove, wash, and
note the comparative strength of the cotton and linen threads.
Cotton will be destroyed in 2. minutes or less; linen as a rule
not so quickly.

TESTS ON LIGNOCELLULOSE.

(a) Structure.— Examine carefully the character of the fibers,
e.g., hemp or jute.

(6) Phloroglucinol Test.— Phloroglucinol, in HC1, gives a deep
magenta coloration with any of the lignocelluloses.

The reagent is prepared by dissolving the phenol to saturation
in HC1 (1.06 specific gravity).

(c) Saturate moist jute fiber, held in a glass tube, with
chlorine gas and then pass SO2 through it. Note the character-
istic reaction, a deep magenta color.

I2O HOUSEHOLD CHEMISTRY

TESTS ON PAPER.

Determine starch as filler with iodine solution. Determine
"size" by moistening the paper with Millon's reagent and warm-
ing gently.

Parchment Paper. — Dip starch-free paper in a cold mixture of
water and HzSCX (2:3), withdraw quickly, wash in clear water
and dry. Compare with an untreated sample. Make the iodine
test. (Cellulose in the presence of certain dehydrating agents
responds to iodine.)

PRACTICAL WORK ON CARBOHYDRATES.

I. EXAMINATION OF CEREALS.

Materials — Ready-to-eat cereals of different types — flaked and
shredded. Uncooked cereals — rolled and granular.

Method: I. Grind samples fine in mortar. Make cold water
solution. Filter. Examine filtrate as follows:

a. For soluble starch (iodine).

b. For dextrin. Add carefully to 95 per cent, alcohol.

Note precipitate. Continue adding the filtrate, observ-
ing whether the precipitate decreases in amount. If
so, the alcohol has been diluted below 60 per cent.,
and dextrin has gone into solution. Starch remains
insoluble. If much dextrin is present iodine will show
it.

c. For reducing sugar. Make Fehling's and Barfoed's

tests.

d. For protein. Make Millon's test (see p. 148).

2. Stain a portion of the residue with iodine and examine
under the microscope for unbroken starch granules.

3. Ash determination. Char 5-10 grams of oats, bran or corn
meal in a 3-inch porcelain dish, cool and extract the mass with
boiling distilled water. Test this solution for K, Na, Ca, Mg,
SO*, Cl and PCX. Dry the extracted char and ash in a muffle,
cool, add a few drops of concentrated HC1 and take up with
distilled water. Filter if necessary and test the filtrate for Fe,
Ca, Mg, PO«.

HOUSEHOLD CHEMISTRY 121

II. COOKING OF CEREALS.

Cook different cereals for the minimum time stated on the
package. Observe condition of granules under microscope.
(Note that a ruptured granule does not always lose its form or
contents.) Observe again after a longer cooking.

III. PREPARED SOUPS.
Treat prepared dried puree soups as in II and observe.

IV. CRACKERS, BREAD, TOAST, ETC.

Examine as in I for unchanged and changed starch, dextrin
and reducing sugar. Compare under microscope stained slides
of bread from crust and center of loaf.

V. POTATOES.

Bake and boil until cooked. Examine under microscope.
Make salivary digestion test on well-cooked potato, examining
under the microscope the condition of the granules in the dextrin
and maltose stages.

VI. HYDROLYTIC CHANGES.

Test sugars for reducing action after boiling with cream of
tartar (fondant making), lemon juice, or other acid fruit juice.
Note time required for hydrolysis and the completeness of the
change. Make similar tests on starch and compare with sugar
as to quickness of action.

VII. HONEY AND SYRUPS.
Test for cane and invert sugars.

VIII. THICKENING POWER.

Note comparative thickening power of potato, corn, and wheat
starches, and time required for cooking.

IX. VEGETABLES AND FRUITS.

Test oranges, lemons, apples, carrots, beets, etc., for sugar
and reducing sugar.

CHAPTER VIII.

FRUITS AND FRUIT JUICES.

Composition. — Analyses of fresh fruits show such simi-
larities in composition that a general description is suf-
ficient. The percentage of water is always high, being
from 75 per cent, to more than 90 per cent, in the edible
portion.1 The next highest constituent is the carbohy-
drate bodies.

The carbohydrates in ripe fruits are principally glu-
cose and fructose. Starch and acids decrease as fruit
ripens; invert increases. Sucrose normally disappears
with the increase of invert. Many fruits, especially
berries, contain little or no sucrose; in apples, pears,
peaches, apricots, oranges, plums and pineapples the
amount is comparatively high. Celluloses, forming the
fiber content, are of course a considerable carbohydrate
part of some fruits. Pectose is found combined as
pectocellulose in the lamellae of cell walls. When hy-
drolyzed with dilute acids or alkalies, or by pectase, an
enzyme present in ripening fruit, pectose changes to
pectin. The former is insoluble in water, and may be
decomposed into a number of substances known as
pectinic acids, usually found combined with calcium.
The term pectinase is applied to the enzyme which coag-

1 Fruits and Fruit Products, Bull. 66, U. S. Dept. Agric., Div.
of Chem.

Bull. 28, Atwater and Bryant, Idem.

HOUSEHOLD CHEMISTRY 123

ulates the juices containing the dissolved pectinous sub-
stances, forming the so-called fruit jellies.1

This reaction is conditioned on the presence of lime,
and the establishment of a certain equilibrium between
the enzyme and the concentration of the fruit acid and
the calcium salts. Fleshy roots and fruits' — carrots, tur-
nips, apples and pears — are especially rich in pectocellu-
loses, but many other fruits, e. g., currants, possess con-
siderable amounts. Preparations of pectose from vege-
table sources for jelly making are now on the market.

In unripe fruits there is often much tannin, which dis-
appears as the fruit ripens.

Acidity. — The acidity of most fruits is due to mix-
tures of organic acids and acid salts, such as acid potas-
sium tartrate. Citric, malic and tartaric acids are often
present, and may be determined separately. However,
for convenience, analysts usually express total acidity as
sulphuric acid.

Ash Constituents. — In most cases, these show a marked
alkalinity, and consist largely of carbonates of sodium,
potassium, calcium, and magnesium. Sulphates and
chlorides are found only in traces.

Proteins. — The protein content is inconsiderable, sel-
dom reaching more than i per cent, in fresh fruit. Much
of this is insoluble, and appears only in small quantities
in the expressed juice. As a rule, the presence of more
than i per cent, of protein in a jelly would indicate that
gelatin had been used to aid in the gelatinizing of the
article.

1Kraemer: Applied and Economic Botany.
9

124

HOUSEHOLD CHEMISTRY

The following table from the Ann. de Chimie et de
Phys., Vol. 61, gives comparative figures as to content
of reducing sugar, sucrose, total sugar and acid in
various fruits:

Per cent,
of
reducing
sugar

Per cent,
of
sucrose

Per cent,
of
total
sugar1

Per cent,
of acid
figured as
tartaric*

0-345
0.403
0.403
0.057

0.661
0.558
1.148
0.115
0.608
0.287

1-574
0.750

0.253
0.633
1.580

0.550
0.448
1.208
1.288
1.864
0-547
2.485
0.783
4.706

17.26
16.50
12.63
11-55

10.00

9.42

8.72
8.42

8.25
7.16

6.40
5-86
5-82

5.45
5.22

4.98
4-36
4-33
3-43
2-74
1.98
i. 60
1.07
i. 06

0.00
0.00

3.20

0.00
0.00
0.00

5.28

0.36

o.oo
0.68

0.00

o.oo

o-43
2.19

2.OI

6.33
4.22

1.25
5-24
1.04

n-33

0.00

0.92-
0.41

18.37
16.50

15.83

n-55

10.00

9-42
13.40
8.78
8.25
7.84
6.40
5-86
6.25
7.64
7.23

11.31
8.58
5-55
8.67
3-78

13-30
i. 60
1.99
1.47

White heart cherries

Strawberries

Strawberries (different

Queen Claude plums

1 Quoted by Buegnet.
» Quoted by Konig.

ANALYSIS OF A FRUIT.1

Water and Total Solids. — Weigh out about 20 grams of the
pulped fresh fruit, or about as much dried fruit as will give
1 Bull. 66, Div. of Chem., U. S. Dept. of Agric.

HOUSEHOLD CHEMISTRY

3 or 4 grams of dried residue, place in a weighed flat bottom
dish, mix with a weighed quantity (4-5 grams) of freshly ignited
asbestos, add a few cc. of water, mix thoroughly and dry at 100°
for 20 to 24 hours. Estimate water and total solids.

Determination of Ash.— Thoroughly char the above residue in
a porcelain or platinum dish at as low a heat as possible, extract
with water, filter, and wash. Return filter paper and insoluble
material to the dish and thoroughly ignite; add the soluble por-
tion and a few cc. of ammonium carbonate solution, and evapo-
rate the whole to dryness. Now heat to very low redness, cool
in a desiccator, and weigh rapidly. The result is total ash con-
stituents.

Determination of Alkalinity.— Run an excess of N/5 HNOs
into the dish containing the ash. Add a drop or two of methyl
orange. Mix carefully with a rubber tipped stirring rod, and
titrate excess of acid with N/io KOH. Calculate alkalinity as
potassium carbonate.

Total Acids. — Dilute 10 grams of fruit juice or pulped fruit
up to 250 cc., with recently boiled distilled water. In the case of
fruit pulp boil for a minute or two, to dissolve all acid from the
fruit cells. Add phenolphthalein and titrate against N/io KOH.
Calculate as H3SO4.

Scheme for the Separation and Identification of Malates,
Citrates, Tartrates, Oxalates and Acetates. — To the filtered fruit
juice, prepared as in the preceding experiment, add Ca(OH)a,
preferably in the form of milk of lime, until the neutral point is
reached. Avoid excess. (If the fruit juice is neutral at the
start, add CaCla solution as long as a precipitate forms.) Stir
well, filter and wash. Proceed as follows with (i) residue;
(2) filtrate:

I. Residue. (Containing calcium tartrate and oxalate). — Treat
on a filter with acetic acid. Residue is calcium oxalate, soluble
in hydrochloric acid. Filtrate contains calcium acetate and tar-
taric acid. Add 95 per cent, alcohol and potassium hydroxide,
and shake well. On standing acid potassium tartrate appears as
well-defined crystals.

126 HOUSEHOLD CHEMISTRY

2. Filtrate. (Containing calcium malate, citrate and acetate). —
Boil, filter, and wash with hot distilled water. Reserve filtrate.
Residue is calcium citrate. Treat on filter with dilute sulphuric
acid. Residue is calcium sulphate. To the solution add silver
nitrate and dilute ammonia — a white precipitate of silver citrate
forms which does not blacken on boiling. The reserved filtrate
contains calcium malate and acetate. Concentrate, cool, and add
to a large excess of ethyl alcohol. Filter and wash. Residue,
calcium malate. Solution, calcium acetate. To this add sul-
phuric acid and heat. Note odor of ethyl acetate.

Determination of Nitrogen.— Use 5 grams of fruit jelly, or
I o grams of fresh juice or fruit. Follow the Kjeldahl method
described in Chapter XVI. Use 6.25 as the nitrogen factor.

Determination of Carbohydrates. — (a) Reducing Sugar. — Treat
25 grams of fruit juice or pulp with basic lead acetate in excess
(2 to 5 cc.), make up to 100 cc. and filter. Transfer from 25
to 50 cc. — depending upon the percentage of reducing sugar
present — to a 100 cc. flask and add a saturated solution of sodium
sulphate in sufficient amount to precipitate the excess of lead ;
complete the volume to 100 cc., filter, and determine reducing
sugar by Allihn's method. (See Chapter XVI.)

(6) Cane Sugar. — When only a small amount of cane sugar is
present, it is best determined by calculation from the increase
in reducing sugars after inversion. Treat double the amount
of fruit or juice used in (o) with basic lead acetate, make up
to 100 cc., filter, and invert 50 cc. in a 100 cc. flask with 5 cc. of
hydrochloric acid. (See Chapter XVI.) After inversion nearly
neutralize the acid with sodium hydroxide, precipitate the excess
of lead with sodium sulphate, and dilute with water to 100 cc.
Filter and dilute so that the solution does not contain more than
I per cent, of reducing sugar. The per cent, of increase in
reducing sugar after inversion, multiplied by 0.95, equals the
per cent, of cane sugar.

Pentoses and Pentosans. — Furfural Test. — Place 25 grams of
the fruit juice, diluted to 100 cc., in an Erlenmeyer flask, add
HC1 of i. 06 specific gravity and boil. Hold in the vapor a filter

HOUSEHOLD CHEMISTRY 127

paper moistened with a solution of equal parts of anilin and
50 per cent, acetic acid. A bright red color appears on the
paper if more than traces of furfural are present.1

Dextrin. — A qualitative test may be made by decolorizing the
diluted fruit juice with boneblack, and observing the color reac-
tion with iodine. Another method of decolorizing consists in
bringing the solution nearly to the boiling point, then adding
several cubic centimeters of dilute (i to 3) sulphuric acid and
gradually potassium permanganate. Stir until the color disap-
pears.

Alcohol Precipitate. — If alcohol is added in excess to a solu-
tion of a fruit product, such as a jelly, a flocculent precipitate
may form with no turbidity, indicating a pure fruit product. A
white turbidity appearing at once, followed by a thick, gummy
precipitate, shows the presence of glucose. In fresh fruit juices
there is often marked turbidity which is caused by the starchy
matters present.

Experiment in Jelly-Making. — To determine the optimum con-
ditions for gelatinizing fruit juices, treat cranberries, apples,
currants, and other jelly-making fruits as follows:

1. Express the juice from the raw fruit and allow a portion
to stand. Is there gelatinization in any case?

2. Bring another portion to a boil. Cool and observe.

3. Boil other portions for measured periods, increasing in
duration. What is the relation of time to jelly formation?

4. Repeat (2) and (3), adding an equal bulk of sugar to the
fruit juice at the boiling point.

5. Repeat (2), (3) and (4), modifying as follows:

(a) Heat the fruit until the skins burst, and express the juice.

(b) Boil the fruit for 5 minutes and express the juice.

Isolation of Pectin.— Grate fresh white turnips and extract all
solubles with cool distilled water. Macerate the extracted resi-
due with cold dilute HC1 (i : 15) for 48 hours, pour off the
liquid and precipitate pectose bodies by adding an equal bulk of
ethyl alcohol.

1 See Sherman : Organic Analysis.

CHAPTER IX.

FATS.

Fats and oils are widely distributed in vegetable and
animal forms of life. The line of distinction between
a fat and an oil is not closely drawn, but fats are gener-
ally found as solids at about 20° ; oils as fluids. True
fats and oils are esters, in which the base is always
glycerol, although the fatty acids vary. They are there-
fore glycerides, the type formation of which is repre-
sented by the equation :

C3H5(OH)3 + 3C17H36COOH —

glycerol stearic acid

(C,,HS5COO)S C,H6 + 3H20.

glyceryl tristearate
or stearin

As found in nature, fats are not simple glycerides,
but mixtures of two or more. For instance, from mut-
ton and beef fat, a distearopalmitin, a dipalmitostearin
and a dipalmito-olein have been separated.1

The principal fatty acids represented in these mixed
fats are:

1Leathes: The Fats.

HOUSEHOLD CHEMISTRY 129

Saturated Acids. Occurrence.

Butyric, C3H7COOH Chiefly in butter.

Caproic, C5H«COOH In butter (1.2 per cent.); in

coconut and palm oils.

Caprylic, C7HiBCOOH Same as caproic.

Capric, C9Hi9COOH Same as caproic.

Laurie, CnH*COOH Milk (trace) ; coconut and lau-

rel oils.

Myristic, CisH^COOH Milk (trace) ; lard, codliver oil,

nutmeg butter.

Palmitic, Ci0H31COOH In most animal and vegetable

fats, e. g., palm oil, butter,
lard.

Stearic, CnHsBCOOH In most fats, especially solid

forms.
Unsaturated Acids.

Oleic, CiiHssCOOH In most fats and oils.

Linoleic, CnHgiCOOH Linseed oil. This or a similar

acid also in other vegetable
oils, including cotton seed.

Since the fatty acids exist as liquids, semi-solids and
solids, the predominating acid or acids in a fat deter-
mine its character in this respect.

Chemically, the glycerides take their name from their
fatty acid, combined with the suffix "in" — thus, stearin,
palmitin, olein, etc.

Properties of Fats. — Solubilities. — With few exceptions,
fats are practically insoluble in cold water and alcohol,
sparingly soluble in hot alcohol, but dissolve readily in
light hydrocarbons such as petroleum ether and gasoline.
All fats are soluble in ether, chloroform, carbon tetra-
chloride and benzene.

Odor and Taste. — Pure neutral glycerides are nearly

130 HOUSEHOLD CHEMISTRY

all odorless and tasteless. An exception is butyrin,
found in butter, which contains soluble butyric acid.
The smell and taste of natural fats and oils are due to
foreign substances, such as ethereal oils.

Heat Conductivity. — Fats are poor conductors of heat,
therefore they conserve the heat of the body.

Non-volatility. — Fats and oils are non-volatile, there-
fore are called fixed, in contradistinction to the ethereal
oils. A result of this property is the formation of grease
spots.

Crystallinity. — Fats are crystalline; the crystals of
pure fats form a means of identification.

Melting and Solidifying Points. — In passing from the
solid to the liquid state fats do not alter in composition.
The melting and solidifying points of fats are definite
unless the mixture is complicated. The solidifying points
of oils range from a few degrees above zero to about
—28°.

Specific Gravity. — Most oils and fats have a specific
gravity ranging from 0.910 to 0.975 at ^-S-S0-

Effect of Heat. — On prolonged heating in contact with
air, or heated above 250°, fats and oils decompose, with
formation of volatile products, notably acrolein. Acro-
lein is a decomposition product of glycerol :

less 2H2O

CH,OH.CHOH.CH2OH •— CHa:CH.CHO.

glycerol acrolein

It has a peculiar irritating odor characteristic of burning
fat, and its formation is a simple means both of identify-
ing the presence of a fat and distinguishing between a
true fat or oil and a hydrocarbon.

HOUSEHOLD CHEMISTRY 13!

Emulsification. — This is a physical change brought
about by agitating a fat in the fluid state with some emul-
sifying agent such as egg albumin or soap solution. The
fat is broken up into tiny globules which are coated with
the tenacious medium and thus prevented from coal-
escing. Emulsions are more or less temporary, as in the
case of mayonnaise, or the fat in freshly drawn milk, or
permanent as in certain commercial preparations. Emul-
sification increases the area for chemical action in soap-
making and fat digestion.

Drying Oils* — Three classes of oils are recognized:
Non-drying, semi-drying, and drying. The distinctions
are made according to their tendency to form a dry,
elastic film on exposure to the air. The drying prop-
erty in an oil is due to the presence of unsaturated fatty
acids, which readily become saturated by combination
with oxygen. Linseed oil is an example of an oil which
quickly undergoes oxidation and is converted into a
varnish. In this case drying is greatly hastened by a
previous boiling of the oil.

Iodine Value. — The degree of unsaturation in a semi-
drying or drying oil can be determined by the amount of
iodine it will take up in the formation of addition prod-
ucts. This is known as the iodine number or value of
the oil.

Hydrogenation. — By a process comparatively new, fats
and oils containing unsaturated fatty acids are made to
take up hydrogen by catalytic action and become sat-

132 HOUSEHOLD CHEMISTRY

urated compounds. Such fats are now being put on the
market for edible purposes and for soap-making.

Hydrolysis. — The hydrolysis of fats, as well as of
esters in general, is called saponification. The change is
a splitting of the fat into its components — glycerol and
fatty acids — illustrated by the reaction :
(C17H35COO)3C3H5 + 3HOH —

stearin

3C17H35COOH + C3H5(OH)3.

stearic acid glycerol

Moisture alone will not effect hydrolysis of fats in any
definite length of time: a catalyst is necessary to accel-
erate the change. Heat, acids or alkalies, and enzymes
act as catalytic agents. At a temperature of 200° or
more, water, e. g., superheated steam, attacks glycerides.
If dilute HC1 or H2SO4 is used, the saponification occurs
rapidly with less heat. Quick hydrolysis is also brought
about by heating the fat with an excess of an alcoholic
solution of caustic soda or potash. In this case the fatty
acid set free unites with the alkali to form soap (see next
page, and Chap. XV). If fat-splitting enzymes are pres-
ent, hydrolysis may be brought about by moisture at nor-
mal temperatures. These enzymes occur in seeds con-
taining vegetable oils, and during germination are active
in changing the fat to a form utilizable by the embryo.
As the quantity of enzymes in the filtered commercial oils
is small, the per cent, of free fatty acid they contain is
likewise small as a rule, and hydrolysis does not proceed
if they are protected from air and moisture, or are not
in contact with the organic material from which they
have been extracted. Under the reverse conditions the

HOUSEHOLD CHEMISTRY 133

formation of free fatty acid may proceed to a consider-
able degree even in refined oils.

Rancidity. — Although a fat or oil may have an acid
reaction, it is not necessarily rancid — the terms are not
synonymous. Acidity precedes rancidity ; the change to
the latter state is supposed to be due to oxidation of free
unsaturated fatty acid by the oxygen of the air, in the
presence of light. The peculiar taste of rancid fat is
caused by these oxidation products. Bacterial action is
not necessary to the change, for a sterile fat may become
rancid, but the presence of foreign substances may favor
enzyme or bacterial hydrolysis of the glycerides. Butter
for this reason easily becomes rancid, as some protein
material may be present. A high olein content predis-
poses to rancidity hence olive and similar oils should be
protected from contact with air and direct sunlight.

Soap-Making Property. — Fats being esters are partic-
ularly susceptible to hydrolysis. When this is accom-
plished through the agency of metallic hydroxides, the
separated acids combine with the bases to form a class of
substances, usually described as soaps. Only the potash
and soda compounds are soluble in water and possess
detergent properties. The insoluble soaps find various
commercial uses as lubricants, paints and in dyeing op-
erations.

By the use of NaOH the changes are as follows :

(1) (CuHuCOO.C.H. + 3HOH —

3C17H35COOH + C3H5(OH)S.

(2) C17HS5COOH + NaOH -~ C17H85COO Na + HOH.

sodium stearate
or hard soap.

134 HOUSEHOLD CHEMISTRY

The sodium salt forms a hard mass which deliquesces
and becomes harder on exposure to air. The potash
compound separates as a soft mass which deliquesces in
air to a jelly-like substance. These characteristic proper-
ties are commonly expressed by the terms hard and soft
soap.

Soluble salts of lime combine with soda or potash soaps
to form the insoluble lime soap (C17H35COO)2Ca (cal-
cium stearate), the typical reaction with soap in hard
waters.

EXPERIMENTS ON FATS.

Ultimate Composition.— Hydrogen and Oxygen in the Form of
Water. — Heat 20-25 drops of clear olive oil in a clean dry test
tube. Note the watery deposit in the cooler part of the tube;
some of this running back will cause the fat to crackle.

Glycerin. — Continue heating the tube until dense fumes arise
from the boiling liquid. These are due to acrolein, CH2 : CH.CHO,
a decomposition product of glycerin. Note the odor and explain
the presence of glycerin.

Carbon and Hydrogen as Hydrocarbons Resulting from the
Breakdown of the Fatty Acids. — Pour the cold tube contents
into a clean dry porcelain dish and heat slowly but strongly over
a low flame. Note the gradual darkening of the liquid due to
freeing of carbon and the tarry coat on the rim of the dish
(hydrocarbons). At this point hold a lighted match over the
dish and note the inflammable character of the vapor (hydro-
carbon gases). Extinguish the flame and continue the heating
until only a black residue remains. This is carbon; prove it by
burning off.

Extraction of Pure Fat from Animal Sources. — Weigh 10 grams
of beef suet cut up in small pieces. Place in a small evapo-
rating dish and heat over hot water until translucent. Then

HOUSEHOLD CHEMISTRY 135

strain through muslin into a porcelain dish, squeeze out the cloth
and reserve the liquid for tests on fats.

Transfer the residue to a small mortar, add 10 cc. of strong
alcohol, grind well. Pour this mixture into a small flask, wash
out the mortar with more alcohol and add the washings to the
flask. Finally close the flask with a cork bearing a condenser
tube 24 inches long, support on a ring stand over a water-bath
and heat for a few minutes. Remove from the heat and when
the suspended matter has settled, uncork the flask and pour the
clear liquid on a small filter, allowing the filtrate to run into a
large test tube. To the residue in the flask, add 20 cc. of ether,
insert the cork and condenser and cautiously heat in warm water
until the liquid boils. Then transfer the entire contents of the
flask to a small filter and collect the filtrate in the same tube as
before. Close the test tube with a loose cotton plug and allow
it to stand until crystals deposit from the liquid. Examine these
under the microscope and draw a diagram of them. Wash the
residue from the last filtration with a little ether, squeeze out,
spread on the muslin and dry. Take it up with a little water,
add a few drops of Millon's reagent, and heat gently. A red
color indicates protein matter.

Make the following tests on the rendered (extracted) fat:

1. Sudan HI. — Make a grease spot in the center of a small
piece of filter paper. Dip the paper in Sudan III. Wash in two
or three changes of alcohol until the dye is discharged from the
paper surrounding the spot. The fat retains the color.

2. Solubility. — Test the solubility of small portions of fat in
separate test tubes containing cold water, cold alcohol and cold
sodium carbonate solution. Cautiously heat all to boiling. Re-
cord and compare the results.

3. Absorption. — Place a small piece of fat on a filter paper and
heat until the fat melts ; note the result and compare with hydro-
carbons.

4. Formation of Acrolein. — Rub a small piece of fat in a mor-
tar with some acid potassium sulphate, transfer the mass to a

136 HOUSEHOLD CHEMISTRY

clean, dry test tube and heat cautiously; note the peculiar dis-
agreeable odor of acrolein and the reducing effect of the alde-
hyde on a strip of filter paper moistened with ammoniacal silver
nitrate.

5. Emulsification.— Shake together a few cc. of codliver oil
and dilute sodium carbonate. Notice the resulting white mass
which is called an emulsion; what well-known liquid is similar
in appearance? Examine two or three drops of this emulsion
under the microscope and note the character of the compound.

Repeat the experiment, using a few drops of olive oil and a
solution of albumin.

6. Saponification with Alkali. — To about I gram of fat in a
low flask fitted with a reflux condenser add 25 cc. of alcoholic
potash solution, and boil. Replace the liquid lost by evaporation
with alcohol. As the heating progresses, the mixture should
become homogeneous; if it does not, add a little more potash
and boil until clear (saponified). Remove the cover and evapo-
rate the bulk of the alcohol, finally adding hot water and heating
until all alcoholic odor has disappeared. Cool the liquid, divide
into three parts and use in (7) and (9).

7. Precipitation and Decomposition of Soap. — To one portion
add a saturated solution of salt. Notice the curdy precipitate
(soap). Filter off this precipitate, try its solubility in cold water.
Repeat the test using strong caustic soda in place of salt. Acidify
another portion of the dissolved soap with dilute sulphuric acid.
Note the curdy precipitate (fatty acids). Boil the mixture until
clear, filter and use in test 8.

8. Test the solubility of the fatty acids in water, alcohol and
sodium carbonate solutions. Record results and compare with
the esters.

9. Formation of Lime Soap. — Add an excess of a solution of
calcium chloride to another portion of the soap liquid and notice
the greasy precipitate of calcium stearate which is insoluble in
warm water and alcohol (lime soap, produced by hard waters).

HOUSEHOLD CHEMISTRY 137

10. Determination of Free Fatty Acid. — Take a weighed
amount of olive oil (about I gram), add about 25 cc. of alcohol
which has been neutralized with N/NaOH (one drop will prob-
ably be sufficient) and boil. While hot, titrate against N/io
NaOH. Calculate the percentage of fatty acid in the sample in
terms of oleic acid.

11. Koettstorfer Number. — Weigh out 2.5 grams of fat in a
low flask. Add 25 cc. of approximately N/4 alcoholic potash
solution, cover with a watch glass and heat on a water-bath until
the fat is completely saponified. Cool, and titrate back excess
of alkali with N/2 HC1. Make a blank test in a similar manner
on the alcoholic potash and calculate the per cent, of alkali
absorbed in saponification. This test is used in the case of an
unknown fat to determine its combining ratio with alkali.

12. Iodine Test. — Into each of two test tubes pour 20 drops of
the oil under test. Dissolve the oil with about 5 cc. of chloro-
form. Add 4 or 5 drops of iodine solution to one of the samples ;
cork and shake. To insure an excess of iodine, test by placing
i drop of the mixture on filter paper. Observe the change in
color in the tube to which iodine has been added, in case the oil
contains unsaturated fatty acids.

13. Extraction of Fats from Cereals or Nuts. — Grind the
sample to a fine powder and dry in an air bath at ioo°-io5° to
constant weight. Weigh from 2 to 3 grams of the dried material,
place in an extraction shell, and cover loosely with absorbent
cotton. Extract in a Soxhlet apparatus with water- free ether
for about 16 hours, allowing the extract to run into a weighed
flask. Use a water-bath, or better, an electric plate, to avoid
danger from overheating the ether. Finally evaporate the con-
tents of the flask to constant weight and estimate the per cent,
of fatty material removed in the ether extract.

14. Special Tests for Cottonseed Oil— (a} Becchi's Test.— To
5 cc. of the oil in a 6-inch test tube, add an equal volume of

138 HOUSEHOLD CHEMISTRY

silver nitrate dissolved in alcohol (i per cent, solution) ; close
the test tube with a cotton plug and keep it in boiling water for
10 to 15 minutes. A darkening of the mixture indicates cotton-
seed oil. The acids in cotton-seed oil quickly reduce the silver
nitrate; those in olive oil only after some time.

(&) Halphen's Test. — To 5 cc. of the oil in a 6-inch test tube
add 5 cc. of amyl alcohol and 5 cc. of carbon disulphide contain-
ing a little free sulphur. Close the test tube with a loose cotton
plug and keep in hot water away from an open flame for l/2 hour.
A red coloration indicates cotton-seed oil. This is a very deli-
cate test.

Butter.

Composition. — Butter is a familiar example of a typical
fat of variable composition. Its composition is under-
stood better than that of any other known fat mixture.
Average analyses give the following constituents :

Per cent.

Water 12 to 16

Fat 82.5 to 84

Curd 0.5 to 2

Ash 2+

Butter fat contains more butyrin and less stearin than
other food fats. In order of amount, the fats in butter
are palmitin, olein, myristin, butyrin, laurin, stearin,
caproin, caprylin, caprin.

The curd may consist of both milk protein and lactose.

A fat soluble vitamine1 is also found.

SPECIFIC TESTS.

Wash a teaspoonful of melted butter in several waters until
free from salt. Prove this by making the silver nitrate test on

1Vitamines are substances present in certain foods and absent
in others, which are essential to normal nutrition. They are of
undetermined chemical composition, and at present are classified
as Fat Soluble A and Water Soluble B and C.

HOUSEHOLD CHEMISTRY 139

the last washing. Note any difference between the first and last
washings when tested with litmus paper. Explain. Cool and dry
the washed butter between filter paper, melt, and dissolve in
gasoline. Filter the resulting solution and wash the residue on
the paper with gasoline until a drop of the washings evaporated
on paper leaves no greasy stain; dry and note the character of
the residue (curd). Moisten with Millon's reagent, heat and
note result.

Spoon Test. — Gently heat a piece of butter about the size of
a cherry in a tablespoon. If it froths without spattering, it is
pure butter. If it foams and spatters it is renovated butter; if
it spatters only, it is oleomargarine.

Butyric Acid Test.— In a 4-ounce narrow neck flask, fitted with
a one-holed rubber stopper, put about 2j^ grams of butter.
Saponify with caustic potash. Decompose the resulting product
with dilute sulphuric acid in excess. Then distil the product
gently, using a bent tube condenser. Butyric acid will distil at
about the temperature of boiling water. Allow the distillate to
drop into a funnel containing moist filter paper. This causes
the retention of fatty acids (other than butyric). Below the
funnel is placed an Erlenmeyer flask containing distilled water
made alkaline by adding 2 drops of 10 per cent. NaOH, and
tinted with phenolphthalein. The disappearance of the pink color
will occur when sufficient butyric acid has passed over to neu-
tralize the soda.

10

CHAPTER X.

PROTEINS.

The proteins are the chief nitrogenous constituents of
both plants and animals. Owing to their complex nature,
the exact chemical structure of protein bodies has not
been determined, but they are regarded as anhydrides of
amino acids, since they yield these acids on hydrolysis.

The elementary composition of all proteins includes
carbon, hydrogen, oxygen and nitrogen, with sulphur in
typical forms. These elements are found in the follow-
ing average ratio: Carbon 51-55 per cent., hydrogen 7
per cent., nitrogen 15-19 per cent., oxygen 2030 per
cent., sulphur 0.4-2.5 per cent. In addition, phosphorus
is frequently found in direct or indirect combination with
the protein molecule, and iron and calcium appear in
some cases.

The large size of the protein molecule can be judged
by the formula assigned to globin, one of the simplest
forms : C726H1174N194S3O^14.

/ Classification. — Proteins are classified principally on

*"fne basis of differences in solubilities and hydrolysis.

The classification which follows is the one recommended

by the American Physiological Society and the American

Society of Biological Chemists :

HOUSEHOLD CHEMISTRY

141

Proteins

Non- proteins

•

Albumins

Globulins

Glutelins

Simple J Alcohol
Solubles

Albuminoids

Histones

t Protamines

Nucleoproteins

[ Conjugated

Glycoproteins
Phosphopro-

teins

Haemoglobins
I/ecith oproteins

Proteans

Primary

Metaproteins

derivatives

Coagulated

Derived

I

proteins

(

Proteoses

Secondary

Peptones

I derivatives I

Peptides

f Extractives

Amides

( Amino acids

In this classification the group called simple proteins
hydrolyze to amino acids, conjugated proteins yield pro-
tein decomposition [products and some other body. This
latter substance is nuclein in the nucleoproteins, a car-
bohydrate in the glycoproteins, a phospho body in the
phosphoproteins, haematin in haemoglobins, and a fatty
substance in lecithoproteins. The derived proteins are
changed forms produced by the action of heat, acids or
alkalies, or enzymes.

Occurrence and Solubilities. — Albumins. — In plant and
animal bodies, such as egg, plant, lact and serum albu-
mins. Soluble in pure water, precipitated by complete

142 HOUSEHOLD CHEMISTRY

saturation with ammonium sulphate, but not by saturated
magnesium sulphate or sodium chloride.

Globulins. — In animal bodies fibrinogen and derived
fibrin, and myosinogen and derived myosin show glob-
ulin characteristics. Other forms are egg serum and
lact-globulin. Examples in plants are legumin and
edestin. Globulins are not soluble in water or in dilute
acids, but dissolve in dilute solutions of inorganic salts.
They are precipitated by saturation with magnesium sul-
phate or sodium chloride, or by half saturation with
ammonium sulphate.

Glutelins. — Found in cereals; as glutenin in wheat and
oryzenin in rice. Insoluble in all neutral solvents but
readily soluble in very dilute acids and alkalies.

Alcohol-Solubles (Prolamines). — Gliadin (in wheat,
combining with glutenin to form gluten in a dough mix-
ture) ; zein (maize); hordein (barley). Insoluble in
water and absolute alcohol, soluble in 70-80 per cent,
alcohol.

Albuminoids (Scleroproteins). — Keratins of horn, hair,
nails, egg membrane ; collagen of white connective tissue,
ossein of bones and elastin of yellow elastic tissue, yield-
ing gelatin; silk gelatin and fibroin. Insoluble in all
neutral solvents. Gelatin, a derived form, dissolves in
hot water.

Histones. — Found combined with nucleic acid, forming
certain nucleoproteins, e. g., in the nuclei of blood cor-
puscles of birds, in the thymus gland, etc. Soluble in
water, insoluble in very dilute NH4OH.

HOUSEHOLD CHEMISTRY 143

Protamines. — Simple in composition; found in con-
junction with nucleic acid in spermatozoa of certain fish.
Soluble in water.

Nucleo proteins. — Widely distributed; form chief pro-
tein constituent of nuclei ; contain nucleic acid combined
generally with albumins, histones, or protamines.

Glycoproteins. — Ovo-mucoid; mucin of mucous mem-
brane. Soluble in dilute alkalies; mucins reprecipitated
by acetic acid, mucoids are not.

Phospho proteins. — Caseinogen of milk, vitellin of egg
yolk. Insoluble in water; readily soluble in alkalies,
forming salts ; precipitated by acids.

Haemoglobins ('Chromoproteins). — Chromogenic sub-
stances, e. g., haemoglobin in blood.

Lecithoproteins (Lipoproteins). — These are nitrogen-
ous bodies combined with a fat radicle. Examples are
lecithans and phosphatides. Occur in yolk of egg, milk,
etc.

Proteans. — Occur as insoluble products apparently re-
sulting from the incipient action of water, very dilute
acids, or enzymes.

Metaproteins. — Found in partial hydrolysis of proteins
by the action of acids or alkalies ; known as acid or alkali
albumin or globulin, etc. Insoluble in water, soluble in
dilute acids or alkalies, precipitated by alcohol.

Coagulated Proteins. — See coagulation.

Proteoses. — Intermediate products of protein digestion.
Soluble in water, precipitated by alcohol or saturation
with ammonium sulphate.

144 HOUSEHOLD CHEMISTRY

Peptones. — Further products of proteolysis. Soluble
in water and saturated ammonium sulphate. Precipi-
tated by alcohol.

Peptides. — Simple hydrolytic products of the protein
molecule, which readily yield two or more amino acids
on further hydrolysis. An example is glycyl-glycine
H2N.CH2.CO.NH.CH2COOH.

Extractives. — Creatin and creatinin, found in muscle.

Amides. — Urea, asparagine in asparagus.

Amino Acids. — Simple decomposition products, of the
proteins.

Properties. — i. General. — Proteins are bodies of high
molecular weight, optically active, colloidal, and gen-
erally colorless. Most proteins are amorphous, but some
have been obtained in crystalline form, e. g., edestin
from hemp seed. They are both acid and basic in re-
action.

2. Coagulation. — Many proteins, especially albumins
and globulins, undergo a precipitation known as coagu-
lation, on heating their aqueous solutions. The chem-
ical change between the water and the protein is not
clearly understood. Complete coagulation is only ob-
tained in slightly acidified solution. Coagulated proteins
are insoluble, and cannot be reconverted into the original
protein substance. Different factors affect rapidity of
coagulation, so that a range of temperature is usually
given as the coagulation point of any specified protein.
The hardening effect of alcohol on proteins is a form of
coagulation.

HOUSEHOLD CHEMISTRY 145

3. Curdling. — This term describes a precipitation of
protein material by acids or certain salt solutions, espec-
ially observed in the case of milk. The caseinogen in
milk exists as a soluble calcium caseinogenate, which is
broken up by the action of lactic or other acids and the
caseinogen is thrown out of solution — i. e., the milk has
curdled. The calcium caseinogenate can be precipitated
by salting out with sodium chloride.

4. Clotting. — Certain conjugated proteins undergo a
change properly known as clotting, which occurs only
through enzyme action. As seen in milk, the caseinogen
is acted upon by rennin, which produces a soluble hy-
drolytic product, casein. The lime salt of casein is in-
soluble, and clotting can take place, therefore, only if
soluble calcium salts are present to form the insoluble
calcium caseinate. This is the clot produced in junket
and cheddar cheese making. A similar change takes
place in the clotting of the nbrinogen of blood, and, as
far as is known, in the muscle tubes after death, causing
rigor mortis.

5. Hydrolysis. — The hydrolysis of simple proteins
yields the following as the principal decomposition
products :

Protein »-* Metaprotein »-» Proteoses »-»• Pep-
tones »-•• Peptides •—»• Amino acids.
Most albumins and globulins also yield a carbohydrate
substance, which in several cases, e. g., egg globulin, has
been identified as glucosamin.

Phosphoproteins split off an insoluble phosphorus com-

146 HOUSEHOLD CHEMISTRY

pound in the early stages of hydrolysis, which becomes
soluble later in digestion. To this substance the names
para- or pseudo-nuclein have sometimes been given.
Nucleoproteins hydrolyze as follows:

Nucleoprotein

/ \

Protein Nuclein

/\

Protein Nucleic acid (Nucleotide)

Meta phosphoric
acid

/ Nucleoside

\

\

' Purin :

Adenin

1

Guanin

Base s <

Pyrimidin:

Uracil

Carbohydrate :

Thymin

Pentoses t Cytosin

Hexoses

In the laboratory, complete hydrolysis may be effected
by boiling with concentrated HC1 for 6 to 12 hours, or
with 25-33 per cent. H2SO4 for 12 to 20 hours.

TESTS ON PROTEINS.

Ultimate Composition.—!. Nitrogen as Ammonia— Mix some
dried egg with lime and moisten sufficiently to roll into small
balls with the fingers. Place two or three of these balls in a dry
test tube, heat and hold in the vapors a piece of moistened red
litmus paper. Note the result Let the paper dry and observe
the change.

2. Sulphur as Hydrogen Sulphide. — Test the fumes with a piece
of filter paper moistened with lead acetate and note the result.
The following test is more reliable. Fuse a minute fragment

HOUSEHOLD CHEMISTRY 147

of the dried material in a sodium carbonate bead on wire or
charcoal, cool, dissolve the melt in warm water in a porcelain
dish and add a dilute solution of sodium nitroferrocyanide
NaaFe(CN)5NO; a purple color indicates sulphur.

3. Hydrogen and Oxygen as Water. — Observe the condensa-
tion of water in the cooler part of the tube.

4. ^Carbon. — Observe the blackening effect produced by the
freeing of the carbon.

5. Phosphorus. — Place the well charred residue in a small por-
celain dish, moisten with concentrated HNOS and heat gently
until excess of acid has been vaporized, then heat strongly until
the carbon has been entirely consumed. Cool the residue, moisten
with HNO3, add water, boil and filter if necessary. Test the
clear liquid with ammonium molybdate.

For the purpose of making general and specific tests on the
proteins, a solution of egg albumin prepared according to the
following directions is recommended.

ALBUMIN.

Preparation of Egg Albumin.— Carefully break a fresh egg,
allow the clear white to run into a porcelain dish and set the
yolk aside for future use. Cut the white with scissors or grind
with sand and place a small portion in a wide-mouthed stoppered
bottle, add 10 volumes of distilled water, shake until it froths
and invert over a small casserole of water. When the froth and
insoluble protein particles float on the surface, carefully with-
draw the cork and allow some of the liquid to mix with the water
in the casserole. The liquid will probably be opalescent, due to
traces of globulin; if strongly so filter through muslin, test the
fluid with litmus paper and if alkaline neutralize with weak
acetic acid (2 per cent).

i. General Tests.— (o) Nitric Acid (Xanthoproteic reaction). —
To a small portion of the filtered liquid, add strong nitric acid.
This forms a white precipitate which turns yellow on heating;
now cool and add ammonia — it becomes orange. Compare with
spots on the skin or woolen cloth produced with HNO8.

HOUSEHOLD CHEMISTRY

(6) Biuret Test. — To I inch of 10 per cent, caustic soda or
potash, add dilute copper sulphate, drop by drop, until a faint
blue color but no precipitate remains in the liquid after shaking;
now add the protein solution. A violet color indicates protein;
a pink, peptone.

(c) Precipitation Tests.— Solutions of the proteins are precipi-
tated by the following reagents :

Alcohol.
Tannic acid.
Picric acid.

(d) Coagulation by Heat. — Heat some of the fluid to boiling
and at the same time add, drop by drop, very dilute acetic acid
(2 per cent.) as long as a precipitate forms; note that this pre-
cipitate does not appear unless the solution is acid. Attempt to
filter some of the albumin through a wet filter paper; prove by
one of the above tests that no protein is in the filtrate.

2. Special Tests for Albumins and Globulins.— (a) Millon's.—
To a small portion of the solution, add Millon's reagent and
heat. This forms a white precipitate which turns red on cool-
ing, or gives a red color if only a trace of protein is present.
Avoid using Millon's in the presence of sodium chloride.

(fc) Heller's Test. — Place some strong nitric acid in a test tube
and allow a solution of albumin to flow gently down the sides
of the tube; a white ring of precipitated albumin forms at the
junction.

(c) Metaphosphoric Acid Test. — Add a solution of albumin
to a very little cold freshly prepared metaphosphoric acid and
note the precipitate formed.

(d) Adamkiewicz's Test. — Warm the protein solution in a por-
celain dish with a mixture of I volume concentrated HaSO4 and
2 volumes glacial acetic acid. A red violet color indicates pro-
tein. Gelatin does not give this reaction.

(e) Precipitation Tests. — To portions of the solution in sepa-
rate test tubes add:

HOUSEHOLD CHEMISTRY 149

Acetic acid and potassium ferrocyanide.
Mercuric chloride.
Lead acetate.

3. Separation Testa.— (a) To a portion of the solution, add an
excess of dry crystallized ammonium sulphate, shake vigorously.
Albumin and globulin will be precipitated, probably in a changed
form. Filter through a good grade of paper and make biuret
test.

(fc) To a portion of the solution, add dry sodium chloride or
magnesium sulphate to saturation. Globulin is precipitated.
Filter, and test nitrate with either nitric acid or Heller's test.
This is a somewhat imperfect method of separating albumin and
globulin.

4. Indiffusibility. — Place some of the solution in a dialyzer of
parchment paper and suspend the whole in a beaker of distilled
water. Test the water subsequently for chlorides with silver
nitrate and also for protein by the biuret test.

5. Proteolysis.— (a) Acid Metaprotein—To undiluted egg white
add concentrated HC1 ; note the copious precipitate of albumin
(coagulated). Heat gently until the mass dissolves resulting in
a violet solution. Cool some of this liquid, testing separate por-
tions as follows :

1. Heat to 70° by placing the test tube in hot water and rais-
ing the temperature gradually. Does any coagulation appear?

2. Neutralize with dilute caustic soda, filter and make the
biuret test on the residue.

3. Add a few drops to 15-20 cc. saturated sodium chloride.

4. Add a few drops to 15-20 cc. 95 per cent, alcohol.

(6) Alkali Metaprotein. — Treat undiluted white of egg with
strong alkali ; note the clear j elly-like mass which results. Heat
to clear solution and dilute some of this with water. Make the
following tests:

1. Heat to 70°, as above.

2. Neutralize with dilute acetic acid, filter and make the biuret
test on the residue.

150 HOUSEHOLD CHEMISTRY

3. Add a few drops to 15-20 cc. saturated sodium chloride.

4. Add a few drops to 15-20 cc. of 95 per cent, alcohol.
NOTE. — Weaker solutions of albumin are converted to meta-

protein by treating with a few cubic centimeters of very weak
alkali or acid (o.i per cent.) at about 40° for several hours.

Proteose and Peptone.— The action of pepsin is hydrolytic and
produces both proteose and peptone — a case similar to the pro-
duction of dextrin and glucose from starch. Make a pepsin
digestion experiment as follows :

Coagulate egg albumin by heat. Cut into small wedge-shaped
pieces, put into 3 test tubes and treat as follows:

1. Cover with highly dilute hydrochloric acid (0.2 per cent.).

2. Add a small amount of neutralized pepsin solution (o.i per
cent).

3. Add a mixture of equal parts of pepsin and hydrochloric
acid.

Place all 3 tubes in a beaker of cold water, heat to body tem-
perature and note the time they take to clear; also observe
whether the mass swells ; finally filter all three and test the clear
filtrates for peptone by the biuret test.

GLOBULIN.

Globulin from the White of Egg. — Saturate some of the un-
diluted solution with dry magnesium sulphate, grinding the mass
in a mortar. Observe the precipitate of globulin, filter and test
the filtrate for protein. Now pour water through the insoluble
mass on the filter and test the extract for proteins. Explain.
The yield of globulins obtained from this source is very small
and the following method is preferable:

Globulin (Hdestin), from Hemp Seed. — Extract dry, ground
hemp seed with sufficient 5 per cent, solution of sodium chloride
to cover it well, first grinding the mass in a mortar, then heat-
ing it for about half an hour at 60°. Keep the mixture at this
temperature and proceed as follows:

I. Filter a portion into a warm test tube, through a filter just
previously washed with hot 5 per cent. NaCl. Notice the clear-

HOUSEHOLD CHEMISTRY 151

ness of the filtrate. Cool under running water and observe the
precipitate of crystallized edestin. Filter off a portion and
observe the crystals under the microscope. Warm the remainder
gently, and cool again. What happens?

2. Learn the solubilities of edestin by filtering a few drops of
the clear solution as in (i) into (a) water, (fr) alcohol, (c) satu-
rated NaCl, (d) 5 per cent. NaCl (all at 60°).

3. Filter, and heat gently over hot water until coagulation
occurs. What is the coagulation temperature?

4. Make biuret and Heller's tests on the clear filtrate.

GLUTELINS AND ALCOHOL SOLUBLES.

Preparation of Glutenin and Gliadin (page 142) from Gluten
of Wheat. — Take 25 grams of white bread flour, mix on a por-
celain or glass plate with the least amount of water to make a
stiff dough (12-15 cc.). Do not handle the dough with the
fingers, use a flexible steel knife. Allow the mass to stand one-
half hour covered. Then transfer the dough to a well-washed
and moistened piece of muslin, taking care to clean the mixing
surface and knife thoroughly; tie up the muslin in the form of
a bag and wash under a gentle stream of cool water, manipulat-
ing well with the fingers. Continue the washing until the liquid
runs clear from the bag, and fails to give the test for starch
with iodine. The washings from the gluten will yield wheat
starch by subsidence. Squeeze out as much water as possible
from the bag, untie it, collect and weigh the moist gluten. Treat
a small portion of the gluten with 75 per cent, alcohol as long
as anything is dissolved. The insoluble residue consists of
glutenin. Try the solubility in very dilute acid and alkali. The
alcoholic liquid contains gliadin; separate this by liberal dilution
with water and filtration. Test both the glutenin and gliadin
with HNO8, Millon's reagent, etc.

Gelatin.

By prolonged boiling with water gelatin is produced
from collagen, which is a protein occurring in the con-

152 HOUSEHOLD CHEMISTRY

nective tissue. The sources of both glue and gelatin are
skin, bones, hoofs, hides, etc., but the latter should differ
from glue both as to the condition of the raw material
and the care used in the processes of manufacture.

The following is recommended as a satisfactory method
of preparing gelatin :

Procure raw shin bones of beef and have them well scraped
and sawed into i-inch sections. Treat these sections for 2 or 3
hours, under slight pressure, in a soup digester with the least
possible amount of water. Pass the extract through cheesecloth,
filter into a tall glass cylinder, and when thoroughly cool, remove
the layer of fat. The jelly-like mass remaining is gelatin. Dry
a portion at low temperature and note the result.

TESTS.

Heat the balance of the jelly to boiling. What happens? Par-
tially cool the liquid, divide into ten parts and test as follows:

1. Dilute hydrochloric acid.

2. Alcohol.

3. Acetic acid or lemon juice.

4. Picric acid.

5. Acetate of lead.

6. Salt and tannin.

7. Heller's test.

8. Biuret test.

9. Adamkiewicz's reaction.

10. Using a reflux condenser, boil a water solution of gelatin
for I hour, 2 hours, etc. Cool, and test its gelatinizing power.
Gelatin is hydrolyzed by prolonged boiling, and will not gela-
tinize. The time required may be 8 to 10 hours.

To estimate the quality of commercial gelatins, make the fol-
lowing tests :

I. The amount of ash should not exceed 2 per cent. Burn a
weighed sample to ash of constant weight and estimate the
amount.

HOUSEHOLD CHEMISTRY 153

2. Soak samples 4 hours, then make into a jelly by heating.
Note odor : it should not be offensive. Expose a 5 per cent,
solution to the air 2 days. Note odor.

3. Test gelatinizing power by comparing the firmness of jelly
made by different samples under the same conditions.

4. Make comparative biuret tests. The color should be violet.

5. Make Millon's test. There should be little or no response.

6. Try litmus paper reaction. It should not be alkaline.

The average composition of bone can easily be shown
by the following simple experiments :

1. Boil a piece of raw bone for several hours under pressure
in water, pour off the liquid and allow it to cool. Dry the bone
residue, observe its porous condition, then break off a small
piece, pulverize it and dissolve the fragments in hot dilute HC1.
Boil off the excess of acid, dilute and test the resulting liquid
for phosphates and calcium. Test the original watery liquid for
protein. Does it contain gelatin?

2. Soak raw bone in 10 per cent. HC1 for several days. Re-
move the residual bone from the acid liquid, observe its peculiar
flexible character. Break off a small piece and test for protein.
Evaporate the acid liquid to dryness, ignite gently, take up with
a little HC1, dilute with water and test for phosphates and
calcium.

Compare the results of the two experiments and explain the
action of hot water and cold dilute acid on bone.

Examination of Commonly Occurring Protein Foods. —

Analysis of Eggs. — The previous work done on albumin
(page 148) will suffice for the white of the egg. The
yolk should be treated as follows :

Separation of Fat and Vitellin. — Place one-half the yolk of a
fresh egg in a broad 6-inch test tube, add twice its bulk of 95
per cent, alcohol, cork, shake vigorously, and place in water at
55° to 60°. When the mixture has separated into layers, decant
the clear upper layer through a filter into a clean porcelain dish,

154 HOUSEHOLD CHEMISTRY

and treat as in (i). Repeat the extractions until the residue
in the tube is nearly white. Finally transfer it to a filter, wash
with another portion of warm alcohol, and dry over warm
water. The granular mass resulting is principally vitellin. Treat
as in (2).

(1) Fat. — Evaporate the alcohol extract over hot water until
no odor of alcohol remains. Note the yellow liquid oil. Take a
portion and test for a fat. Add a few drops of HNO3 to the
remainder and burn to ash; divide the ash in two portions and
take up with a few drops of concentrated HC1 and HNO8 respec-
tively, add a little water to each and heat. Filter if necessary,
test the HC1 portion for iron with ammonium thiocyanate and
the HNO3 portion for phosphoric acid with ammonium molyb-
date.

(2) Vitellin. — Mix thoroughly with 5 per cent. NaCl solution,
keeping the mixture at 60° for 15 minutes. Filter a few drops
into

(a) A large bulk of water made faintly acid with acetic

acid.

(&) 95 Per cent, alcohol.
(c) Saturated salt solution.
What are the solubilities of vitellin?

Heat another portion of the filtrate to coagulating point.
What is it?
Make the nitric acid or Heller's test on another portion.

Shell. — i. Examine a portion of the shell under the low power
of a microscope ; note the physical character. Treat a portion
of the shell with silicate of soda solution (10 per cent.) ; when
dry examine as before. (Silicate of soda is used for preserving
eggs.)

2. Crush and grind the shell, thoroughly extract with warm
water, dissolve the extracted mass with dilute hydrochloric acid.
Note the effervescence. Hold in the fumes a drop of limewater
on the end of a glass rod and note the clouding. What gas is
formed? Filter the HC1 solution and make slightly alkaline with
ammonia, add ammonium oxalate and note the white precipitate

HOUSEHOLD CHEMISTRY 155

of calcium oxalate, insoluble in acetic acid. From the data
found give the composition of the shell and the changes which
have taken place.

3. Allow an egg to stand in strong vinegar for several hours,
remove, wash in one change of water, and note the peculiar con-
dition of the egg. Examine the acid liquid as in the preceding
experiment.

4. Examine equal portions of the yolk and the white of egg,
separately, for sulphur by mixing with lime and testing with the
lead acetate method given under proteins. Which do you think
contains the greater amount of sulphur?

5. Weigh an egg accurately and repeat the weighing for five
or six succeeding days. Record the results and explain.

For the average composition of the egg, see Sherman: Food
Products.

Muscle.

The muscle mass consists of a series of elongated
tubular sacks of yellow connective tissue (elastin) ar-
ranged in bundles and held together by white connective
tissue (collagen). Interspersed in the mass are fat glo-
bules.

Principal Constituents of Muscle. — Proteins. — The total
proteins of the muscle mass include serum albumin, serum
globulin, haemoglobin, elastin, collagen, and especially
paramyosinogen and myosinogen. These latter yield
myosin on clotting, as shown below :

paramyosinogen myosinogen

soluble myosin

myosin

(clot)
ii

156 HOUSEHOLD CHEMISTRY

The clotting action takes place at death. The globulin-
like myosin is in turn gradually softened by acids set free
by bacterial action (putrefaction) during "hanging."

Carbohydrate. — Glycogen and glucose are generally
present in muscle. They furnish energy for muscle con-
traction, yielding sarcolactic acid as one of the products
of fatigue. Fresh muscle usually contains glycogen, but
on standing this is rapidly changed to bacterial lactic acid.

Extractives. — These are certain nitrogenous non-pro-
tein bodies, principally creatin and creatinin. They give
flavor to muscle, and being readily soluble, are found in
meat extracts and soups.

Mineral Salts. — Principally potassium phosphate, also
chlorides and other compounds of Ca, Fe, Na and Mg,
including a trace of sulphates.

EXPERIMENTS ON MUSCLE.

Cut off the exterior of a piece of lean meat, test the interior
with litmus paper and note the reaction. Then cut the meat in
small pieces, pass through a meat chopper and grind the result-
ing mass in a mortar with clean, dry sand. Take one-half of
the ground mass and extract in a beaker of cold water, stirring
every few minutes. Allow the extraction to proceed for ^2 hour.
Finally filter off a part of the watery extract and test separate
portions as follows:

1. Biuret.

2. Heat over water. At what point does coagulation begin?

3. Add crystals of ammonium sulphate to saturation; filter,
and test precipitate and filtrate with biuret.

4. Determine whether glycogen is present as follows: Boil
with a few drops of hydrochloric acid, neutralize, test with
Fehling's.

Heat the remainder of the water extract to coagulate the pro-
tein and filter. To the filtrate add a few drops of HNO3 and

HOUSEHOLD CHEMISTRY 157

burn to ash. Cool, take up with water, and if cloudy, filter.
Divide into five parts and test for chlorides, sulphates, phos-
phates, calcium and iron.

Take the second portion of the ground meat, wash it free from
blood, and extract it with three or four times its bulk of 10
per cent, sodium chloride, allowing it to stand 24 to 48 hours.
Finally filter off the protein solution and test portions as follows :

1. Try reaction with litmus.

2. Pour a few drops into a large excess of water. Note milky
precipitate of myosin.

3. Heat to coagulating point; what is it? Is the litmus reac-
tion the same after heating?

4. Saturate with salt, shaking vigorously. What effect on the
myosin? Filter. Dissolve precipitate in 10 per cent. NaCl and
make biuret test on solution.

From the composition of muscle and the tests made
deduce the effect on meat of washing, placing in dilute
salt solution, corning, soup making, and roasting.

Beef Extracts.

Composition. — The food value of these extracts is
slight, and their function is to serve as stimulants or
appetizers, and flavoring material. Commercial extracts
contain little if any protein material, since such proteins
as may be extracted are coagulated by heat and removed
by filtration. Home-made extracts and clear soups lose
food value by clarifying. No fats or carbohydrates are
found in the average market extract; the principal in-
gredients are extractives and the mineral salts of muscle.

TESTS ON HOME-MADE AND COMMERCIAL
EXTRACTS.

Make meat extract by steeping lean meat in cold salt water,
gradually heating to a boil and finally under slight pressure.
Pour off the liquid, cool, remove the fat, dissolve some of the

158

HOUSEHOLD CHEMISTRY

jelly in warm water and compare with Liebig's and other meat
extracts made on the commercial scale, by the following tests :

1. Biuret.

2. Glycogen test (Iodine).

3. Creatinin (Weyl's Test).— Add a few drops of a 5 per cent,
solution of sodium nitroprusside, freshly prepared, and cautiously
38° Baume NaOH. A ruby red changing to straw color shows
creatinin.

4. Examine the solid extract under the microscope and note
the cubical crystals of salt and knife-rest forms of creatinin.

5. Clarify beef extract with white of egg, filter and test filtrate
for protein with biuret. Compare with test on beef extract
before clarifying.

Milk.

This term usually refers to cow's milk in market form.
Analyses show that the composition of milk varies with
different breeds of cows, the principal variation being in
the fat content. Approximate averages are as follows.1

Per cent.

Per cent.

Water .

87.2
12.8

3-6
3-3
4-9
0.7

87.0
13-0
4.0
3-3
5-o
0.7

fat. .

ash

In most states, the amount of fat in milk offered for
sale is regulated by law. The New York standard re-
quires at least 3 per cent. fat.

The Fats. — The true fats in milk are glycerides of both
volatile and non- volatile fatty acids. Of the former,

*For detailed composition of milk, see Sherman's Food
Products.

HOUSEHOLD CHEMISTRY 159

butyrin is the most important, forming 5 to 7 per cent, of
the fat content. When hydrolyzed, its free butyric acid
gives a taste and odor to rancid butter. The principal
fats of the non- volatile acids are palmitin in large amount,
stearin, and olein. In freshly drawn milk tiny globules
of fat are held in suspension by the mixed proteins
present, but on standing the emulsion breaks, and the
cream separates more or less completely. However, it
is not until the emulsifying power of the protein is de-
stroyed by the action of lactic acid developed in souring,
that the fat particles run together and are combined in
the form of butter by churning.

Proteins. — The protein constituents of milk are prin-
cipally caseinogen, with small amounts of albumin, glo-
bulin, and fibrinogen. Caseinogen is strongly acid in
character, is insoluble in water, but is held in solution
as a calcium-caseinogenate by the lime phosphates in the
milk.

Carbohydrate. — Lactose is the main form of carbohy-
drate material. In amount it shows less variation than
any other ingredient except mineral salts.

Ash Constituents. — The principal ash constituents are
in the form of lime phosphates, found either combined
with protein or other organic material, such as lecithin, or
free as mineral salts. Combined citric acid is present in
small amount, also chlorides and other salts of Na, K
and Mg. Iron and sulphur are found.

Other Constituents. — Urea, creatinin, lecithin, choles-
terol and hypoxanthine are present in varying amounts;

l6o HOUSEHOLD CHEMISTRY

also a color substance, carbohydrate- and fat-splitting
enzymes, an oxydase, a reductase, and a catalase, and
vitamines.

Fresh milk has an amphoteric reaction to litmus, due
to the fact that it has two classes of phosphates in solu-
tion. Its specific gravity varies from 1.029 to 1.035.

Effect of Heating. — Under the conditions usually em-
ployed for pasteurization (145° F. for I hour) few if
any chemical changes are produced in milk — the object
being to destroy certain pathogenic bacteria. Boiling
milk produces both physical and chemical changes, some
of which are the alteration in the physical state of the
fat globules, a tendency to precipitation of the lime salts,
the destruction of most organisms, and the appearance of
total solids in the skin which forms after boiling. This
formation is not, as sometimes explained, coagulated pro-
tein material, but is due to the concentration of total
solids as the water evaporates.

Souring of Milk. — By the activities of lactic acid
bacteria lactose is decomposed into lactic acid :

C,,HBOn. H,0 — 4C.H.O,.

Other fermentation products may also be formed, such
as acetic, propionic or butyric acid, and some alcohol,
e. g.:

4C8H60, ~ 2C4H802 + 4C02 + 4Hr

lactic acid butyric acid

When the lactic acid reaches approximately 0.5 per
cent., caseinogen begins to be precipitated; the extreme
amount of lactic acid developed is generally about 0.9
per cent. The action of acids on caseinogen has been

HOUSEHOLD CHEMISTRY l6l

described under Curdling (p. 145) but the changes taking
place in this case may possibly be represented by the
expression :

(lactic acid)

Ca-caseinogenate »-»• caseinogen

(soluble) (insoluble)

-j- acid Ca-phosphate.

When baking soda is used with sour milk the acid
caseinogen combines with the alkaline carbonate, form-
ing sodium caseinogenate, carbon dioxide and water.

Action of Rennin. — The clotting action of rennin has
been referred to under Clotting (p. 146). Conditions for
the best action of the enzyme are brought out in experi-
ments on p. 165.

Fermentation with Yeast. — Milk does not readily un-
dergo fermentation with ordinary yeast unless some food
for the yeast is added. For kephir or koumiss a special
yeast ferment is used, which changes the lactose into
alcohol, lactic acid, and various other acid fermentation
products.

TESTS ON MILK.

Physical. — i. Cream Gauge. — Fill to mark with freshly mixed
milk. Allow the tube and contents to rest quietly for half an
hour and read off percentage of top milk from graduated scale.

2. Lactometer. — Fill a tall jar with freshly mixed milk, tem-
perature 60° F. Immerse the instrument and when it comes to
rest read off the percentage of purity on the scale. On the New
York Board of Health lactometer the zero mark records a
specific gravity of i.ooo and the 100 mark a specific gravity of
1.029. In similar manner, determine the purity of skim milk.
Finally, add water and redetermine the purity; how can you
explain the result?

1 62 HOUSEHOLD CHEMISTRY

3. Pioscope Test. — Depends on opacity. Place a drop or two
of freshly mixed milk in the center of the hard rubber disc.
Cover carefully with the glass plate and compare with the stand-
ard scale of colors.

4. Lacto 'scope Test. — Use Feser's lactoscope. Fill the pipette
with milk, allow it to run into the cylinder. Cautiously add
water, shaking after each addition, until the marks on the cloudy
glass rod are just visible through the liquid. Read off and
record the percentage of fat at the level of the liquid.

5. Microscope Test. — Examine a drop of milk under the micro-
scope; add a drop of 10 per cent, caustic soda and re-examine.
What is the result?

Chemical Tests.— i. Using fresh milk, what is the reaction with
delicate litmus paper?

2. Babcock Test (Determination of Fat). — This test depends
on the decomposition of the organic constituents, with the excep-
tion of the fats, which are at the same time set free in the liquid
state and may be measured.

Fill the milk pipette (17.6 cc.) with freshly mixed milk, dis-
charging the contents into the Babcock bottle, add an equal
volume of oil of vitriol (specific gravity 1.8). Mix by revolving
the bottle gently in a small arc, back and forth, until the residue
disappears and the mass is brown in color. Make tests up in
duplicate and whirl them for 5 minutes in the centrifuge over
hot water. Stop the machine, add enough warm water to bring
liquid level half way up the graduated neck of bottle. Replace
them in centrifuge and whirl 3 minutes, allowing machine to run
down. Take out bottle and read per cent, of clear yellow fat
floating on the water.

3. Separation and Identification of Caseinogen. — Dilute 10 cc.
of fresh raw milk with water up to about 100 cc., add slowly
the least quantity (6-8 cc.) of 2 per cent, acetic acid required to
precipitate the caseinogen, warming meanwhile to 60°, filter
through moist fluted paper and reserve the clear filtrate for
test B. Operate with the residue as follows:

HOUSEHOLD CHEMISTRY 163

A. Residue of Caseinogen. Wash several times with the same
amount of hot 95 per cent, alcohol, evaporate the alcohol extract
over hot water, notice the appearance of the oily substance
remaining, and make a fat test upon it. Remove excess of liquid
from the caseinogen residue by pressing between dry filter paper,
and spread out to dry. Dissolve a portion in about 25 cc. of
warm 5 per cent, salt solution, slightly acidified with acetic acid.
Stand in hot water for some minutes and filter. Add a few
drops of the clear filtrate to a saturated solution of salt, adding
dry salt if necessary. What are the solubilities of caseinogen
in salt solutions? Make nitric acid and biuret tests on portions
of the dissolved caseinogen. Add another considerable portion
of the clear filtrate to ammonium oxalate, made strongly alka-
line with NH4OH. Heat and observe white crystalline precipi-
tate of calcium oxalate. Fuse the remaining portion of dried
caseinogen with sodium nitrate in a porcelain crucible, cool, and
extract the contents of the crucible with diluted HNO, (1:5).
Filter, and add a few drops of the clear liquid to (NHOiMoCX
solution. Warm and observe yellow crystalline precipitate, indi-
cating presence of phosphoric acid.

B. Divide the whey filtrate (reserved) into three equal por-
tions.

1. Heat in boiling water and observe the clouding (lactal-
bumin). Filter, test precipitate for protein, and filtrate for lac-
tose with Fehling's reagent.

2. Add potassium ferrocyanide and excess of acetic acid.
Observe the precipitate of lactalbumin.

3. Heat in boiling water, filter off lactalbumin, boil the filtrate
and observe the precipitate, principally insoluble calcium citrate.
Reserve filtrate.

NOTE. — If milk has been thoroughly pasteurized, it will not
respond to the tests for lactalbumin.

C. Evaporate the filtrate, from last test, to dryness; ignite in
the presence of a few drops of HNO3, cool, dilute with water
and test for chlorides, sulphates and phosphates.

164 HOUSEHOLD CHEMISTRY

Analysis of Milk. — Measure 5 cc. of milk with a pipette, trans-
fer it to a weighed shallow porcelain dish and weigh again.
Difference is weight of milk. Place over hot water (kept just
below the boiling-point) to evaporate water present in milk.
Cool and weigh; loss is water, residue is total solids. Total
solids should be 12-13 per cent. To extract fat, add about 10 cc.
of ether to contents of dish, heat over warm water I or 2 min-
utes, decant solution into a second weighed dish. Repeat the
ether treatment three times. When dry, weigh original dish;
the loss is fat. Evaporate ether from second dish, weigh; the
gain is fat and should check the loss.

To extract lactose and soluble salts, treat contents of dish
with warm water. Allow it to stand for several minutes, decant
the liquid; repeat the operation three times. Dry the dish and
Weigh ; loss is lactose and half the mineral salts found in milk.

Ignite the contents of dish to a gray ash; protein matter will
burn off. Cool and weigh ; the loss is protein, residue is insol-
uble salts. Assuming that insoluble salts are one-half of the
total salts, double the figure obtained. To determine amount of
lactose, subtract one-half of total salts from the figure obtained
on lactose and soluble salts. The difference is the amount of
lactose.

Determination of Lactose.— Into a glass stoppered cylinder, put
100 cc. milk and 2 cc. Millon's reagent. Mix thoroughly and
pour into a beaker placed over hot water. Allow the mixture to
stand until all protein matter has precipitated, filter off the clear
whey through moist fluted paper. Make it alkaline with dry
sodium carbonate, adding a little at a time until pink litmus paper
turns blue. If cloudy filter again. Pour into a burette and deal
with it as with sugar. Calculate that 0.068 gram will reduce
10 cc. Fehling's reagent.

Effect of Rennet. — In the following experiments with rennet,
make the tests comparative by using the same amount of milk
and rennet solution throughout, e. g., 10 drops of liquid rennet
to 30 cc. of milk in each case.

HOUSEHOLD CHEMISTRY 165

1. Heat milk to the boiling-point, boil gently for 5 minutes,
replacing any liquid lost during evaporation by hot distilled
water, cool to 40° and add rennet ; note the character and amount
of clot.

2. Boil milk 15-20 minutes, keeping the liquid up to bulk as
before ; cool to 40°, add rennet ; note character and amount of
clot.

3. To the sample of milk, add 1-2 cc. of ammonium oxalate
solution (precipitant for lime), boil for 2-3 minutes, cool to 40°
and add rennet ; note character and amount of clot, if any.
Finally add 5-10 cc. of 5 per cent, calcium chloride solution,
warm to 40° and note the result.

4. Add i cc. of 0.2 per cent. HC1 to the milk and test with
rennet at 40°. Does a clot form? Repeat, using i cc. of 10
per cent. Na2CO8. What is the effect of alkali on rennet action?

5. Note the effect of rennet on separate portions of milk
heated to 30°, 40°, 50°, 80°. Tabulate the results of the above
tests.

Butter-Fats.— Half fill two small flasks (50 cc,), one with pure
and the other with skim milk. Add to each half a volume of
ether and a few drops of caustic soda, cork and rotate well.
Uncork and place in a beaker of warm water and allow them to
remain quiet. In a few minutes, note the layer of oil and ether
floating on the surface. Remove some of the ether layer from
each with a pipette and evaporate at a low heat. Note the differ-
ences in amount of the butter residue.

Souring.— i. Place some milk in a wjde-mouthed bottle, allow
it to stand in a warm place for some days or until sour. Finally
filter off the curd and test the filtrate for lactose and for acidity
by titrating with IO/N alkali, calculating to lactic acid. What
weight of bicarbonate of soda would neutralize the amount of
acid found?

2. Measure standard cupfuls of slightly sour, moderately sour,
and very sour milk. Weigh the amount of baking soda required

l66 HOUSEHOLD CHEMISTRY

to fill a standard teaspoon and add the soda in small amounts
to the milk sample, mixing thoroughly after each addition, and
testing with litmus paper. Determine the weight of soda re-
quired to neutralize the acidity in each of the three samples of
milk, and express the amount in fractional parts of a teaspoon.

Condensed or Evaporated Milks should be diluted with distilled
water to the original bulk and treated as normal milks. The
index of condensation may be estimated by observing the rela-
tive amount of dilution necessary.

Preserved milks commonly contain cane sugar. Dilute a
sample to the original bulk, precipitate the caseinogen with dilute
acetic acid; filter and exactly neutralize the filtrate with sodium
carbonate and test for sucrose with cobalt chloride and caustic
soda.

Formalin in Milk. — Add I drop of ferric chloride solution to
50 cc. of concentrated HaS(X Pour 5 cc. of the mixture down
the side of a test tube containing 20 cc. of the milk under test.
If formalin is present, a violet band will shortly appear at the
contact point of the two liquids.

Analysis of Ice Cream.— For Gelatin.— Dilute 50 parts of ice
cream with 25 parts of water and bring to the boiling point, to
dissolve any thickener other than gelatin that may be present
and not in complete solution. To 10 cc. of the product add an
equal amount of acid nitrate of mercury solution1 and about
20 cc. of cold water. Shake vigorously, allow to stand 5 min-
utes, then filter. If much gelatin is present the filtrate will be
opalescent and cannot be obtained clear. To a portion of the
filtrate add an equal volume of a saturated solution of picric
acid. A yellow precipitate will indicate gelatin in any consid-
erable amount; smaller amounts are shown by a cloudiness. In
the absence of gelatin the filtrate obtained will remain quite
clear.

For Fat. — Make estimation as soon as possible after sample
has melted. Weigh 9 grams of the sample in a Babcock cream

ijour. Amer. Chem. Soc., 1907.

HOUSEHOLD CHEMISTRY l6/

bottle. Add 30 cc. of a mixture of equal parts by volume of
concentrated HC1 and 80 per cent. CH8COOH. Heat on a water
bath until well darkened, but short of charring. Whirl in a
Babcock centrifuge and read the percentage of fat directly. If
the cream is charred, add ether after the whirling, draw off the
layer containing the fat into another Babcock bottle, evaporate
the ether, fill the bottle with water, and again read percentage
of fat after whirling.

Character of Fatty Matter. — For observing the char-
acter of the fat, 30-40 cc. of the cream layer are placed
in a Babcock cream bottle, I cc. of strong mercuric
nitrate solution and 20 cc. of petroleum ether are added,
and after whirling, the ethereal layer is separated, washed
with water, and the ether evaporated.

Cheese.

A product prepared from the caseinogen of milk with
or without the fat. The milk is clotted with rennet, sepa-
rated from the whey, ground, salted, pressed into shape
and cured. The curing operation consists in subjecting
the cheese mass to the action of certain bacteria and
moulds, which form acids, hydrolyze the proteins and
develop flavor and odor.

Cottage cheese is merely finely divided caseinogen pre-
cipitated by the lactic acid of the souring process aided
by the heating and undergoes no further change.

Cheeses are usually made from cow's milk but may be
produced from goat's or ewe's milk or mixtures of all
of them.1

1 For further information, see Vulte and Vanderbilt, Food
Industries, and Wing, Milk and Milk Products.

1 68 HOUSEHOLD CHEMISTRY

EXPERIMENTS ON CHEESE.

Take a sample of well-cured cheese, grind some of it in warm
5 per cent. NaCl solution, filter and reserve the residue.
Divide the nitrate into four parts and test as follows:

1. For acidity or alkalinity with litmus paper and N/io acid
or alkali.

2. For state of protein matter, by biuret test.

3. For soluble mineral matter, *'. e., sulphates, etc.

4. For ammonia and sulphides.

Extract the residue several times with the same portion of hot
neutral alcohol, cool, and test the extract with litmus paper for
fatty acids. When cold, observe the cloudy precipitate of esters.
Separate by nitration and test for free fatty acid and fats.

Divide the extracted residue into two parts and test as follows :

1. For insoluble protein.

2. Burn to white ash and test for insoluble mineral matter —
phosphates, lime, etc.

During the incineration, hold pieces of moistened red litmus
and lead acetate papers in the fumes and record the results.

Cheeses are frequently preserved in wrappings saturated with
borax or boracic acid solution. To determine this, steep some
of the paper wrapping in warm water, filter if necessary, acidify
with HC1 and dip pieces of turmeric paper in the liquid. Dry
these at 212° F. ; a pink color indicates borates.

CHAPTER XI.

BAKING POWDERS.

It is frequently necessary to develop carbon dioxide
for leavening purposes more rapidly than by the agency
of yeast. For this purpose the purely chemical method
by the acid decomposition of carbonates or bicarbonates
is most available.

Undoubtedly the time-honored custom of using salera-
tus (bicarbonate of potash) and sour milk (lactic acid)
furnished the original idea on which the modern mix-
tures were built up. This idea still survives to some ex-
tent in modern practice, but is open to at least two strong
objections. First, bicarbonate of potash is no longer a
commercial article but is replaced by the cheaper and
stronger bicarbonate of soda; still no change is made in
the proportions used. Second, it is very difficult to
estimate the amount of lactic acid in sour milk by simple
means with any accuracy. In fact the quantity is usually
largely over-estimated. When milk shows decided in-
dications of the sour stage only 0.4 per cent, of lactic
acid are usually found. It must be remembered that any
excess of the bicarbonate used is changed into alkaline
normal carbonate by the heat of baking.

For the above stated reasons it can easily be seen that
accurately compounded mixtures (leaving neither alka-
line nor acid residues), retaining their qualities for some
time in the dry state, but ready to develop gas on addi-
tion of water, have a decided advantage. In order to
preserve these mixtures in a dry state, it has been found

I7O HOUSEHOLD CHEMISTRY

advisable to add to them such agents as raw starch and
pulverized lactose, which are perfectly harmless. Such
additions do not usually exceed 25 per cent, of the whole
mass. When used for this purpose the compounds are
known as "fillers."

Modern baking powders may be classed as tartrate,
phosphate, and alum phosphate. All contain bicarbonate
of soda, while the acting acid ingredient varies, as
follows :

Tartrate — Cream of tartar, KHC4H4O6, and some-
times a small amount of free tartaric acid, H2C4H4O6.

Phosphate — Soluble phosphate of lime, CaH4(PO4)2,
and sodium dihydrogen phosphate, NaH2PO4. Alum
phosphate, in which alum is now rarely used, being re-
placed by basic sodium aluminium sulphate or S. A. S.,
Na2S04,Al2(S04)3Al203.

The following reactions show the changes taking place
in using these mixtures :

For tartrates:
KHC4H4O6 + NaHCO, + 3H,O -~

188 84 54

KNaC4H4O6> 4H2O + CO,.

282 44

For phosphates:

2CO2.

CaH,(PO.)f -

234

h 2NaHCO, -f

1 68

CaHPO4 -
136

ioH2O •—

180

f Na2HPO4, I2H2O

358

or

NaH,P04+NaHC08+nHaO— Na2HP04, i2H,0-fC02.

120 84 198 358 44

HOUSEHOLD CHEMISTRY 171

For alum phosphate:

Na2S04Al2(S04)3 A1203 + CaH4(PO4)2 +

586 234

4NaHCO8 + 28H2O —

336 504

A1203 + A12(P04)2 -f CaS04, 2H2O +

102 244 172

3Na2S04, ioH20 -f 4C02.

966 176

It is significant that the sodium phosphate and tartrate
powders leave no insoluble residue except starch, while
the others leave nearly one-third of their weight in in-
soluble mineral material besides the starch. The calcium
phosphate powders yield acid soluble phosphate of lime,
of doubtful utility, and the alum powders, aluminium ox-
ide, aluminium phosphate and calcium sulphate.

The table of comparison on p. 12 is taken from Vulte
and Vanderbilt's Food Industries.

An efficient baking powder can be made at home at a
low cost by combining the following ingredients :
y2 pound cream of tartar.
l/4 pound baking soda.
y\. pound cornstarch.

For maximum efficiency these suggestions should be ob-
served: Dry the cornstarch before combining; mix and
sift the ingredients thoroughly; either make up small
quantities or pack in small tightly closed receptacles.

Ammonium carbonate is sometimes used as a baking
powder, since it yields carbon dioxide when heated :
(NH4)2C08 -~ NH, + C02 + H20.

It will be seen that all the products are volatile, no
residue being left unless an excess of the powder is used.

12

172

HOUSEHOLD CHEMISTRY

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HOUSEHOLD CHEMISTRY 173

In that case an unpleasant taste is noticed in the product.
The amount of powder required is only about one-tenth
as much as of other powders.

EXPERIMENTS.

Tartrates. — Mixtures of cream of tartar and bicarbonate of
soda with starch or lactose filler. Treat a small portion of the
powder with water and after the effervescence has ceased test
a portion of the liquid for starch with iodine solution and for
lactose with Fehling's solution, boil the remainder of the liquid,
cool, filter through fluted paper, and test with litmus paper.

1. Place a few drops of the clear liquid on a slide and allow
it to evaporate spontaneously. Examine the cleft rectangular
crystals of Rochelle salt.

2. Fenton's Test. — Test another portion of the solution by add-
ing i drop of fresh cold dilute solution of ferrous sulphate,
i or 2 drops of peroxide of hydrogen and immediately a large
excess of 38° Baume caustic soda — a violet color appears, due to
tartrates. Evaporate the balance of the solution in a porcelain
dish, char and gently ignite the residue. Note the odor while
carbonizing; what does it suggest? Cool, add water and test
with litmus paper; why is it alkaline?

Neutral tartrates will respond to the silver mirror test.

Tartrate powders may contain a small amount of bicarbonate
of ammonia. To test for this, heat a portion of the powder in
a test tube with caustic soda solution; observe the odor; or hold
a strip of moistened red litmus paper over the mouth of the
tube.

Phosphate Powders. — Calcium hydrogen phosphate or sodium
dihydrogen phosphate, bicarbonate of soda and starch filler.

Treat 2 grams (l/2 teaspoonful) with water and gentle heat
until the gas is expelled. Be careful not to gelatinize the starch.
Filter and test filtrate for calcium, sodium and phosphates. Test
a portion of the residue for starch and treat the remainder with
cold dilute HC1, testing the resulting liquid for calcium, phos-

174 HOUSEHOLD CHEMISTRY

phates and aluminium. From the results obtained decide to what
class of phosphates your sample belongs.

NOTE. — Probably the best method for the determination of
aluminium compounds is to add a few cc. of a solution of the
powder to tincture of logwood diluted with 2 or 3 volumes of
water, finally adding an equal volume of ammonium carbonate.
In the presence of alum the liquid is colored lavender or dark
blue.

Carbon Dioxide Determination by the Scheibler Apparatus. —
Weigh out 500 milligrams of the baking powder, place in the
glass-stoppered bottle belonging to the apparatus. Put a small
quantity of water in the gutta percha tube (two-thirds full).
The columns of water in the apparatus will be at the same level
when the pressure inside of the apparatus is the same as the
atmospheric pressure, and this should be the condition when
the experiment is started. The gutta percha tube is placed inside
the bottle containing the 500 milligrams of baking powder and
the apparatus is then connected up. Be sure the relief valve is
open when the apparatus is put together and closed immediately
afterwards. Incline the generating bottle to allow the water to
come in contact with the powder. Observe the evolution of gas.
Note the height of the water column. Grasp the generating
bottle by the neck and shake vigorously until no more gas is
evolved. Immediately afterwards balance the water columns by
allowing some water to escape into the overflow flask. Read
the figure nearest the level of the water. This reading indicates
the per cent, of gas liberated by the addition of water to the
baking powder, or in other words, the leavening power of the
baking powder. This reading should be in the neighborhood of
10, indicating 100 per cent, efficiency, in a fresh tartrate powder.

CHAPTER XII.

TEA, COFFEE, CHOCOLATE AND COCOA.

Tea consists of the cured, dried and rolled leaves of a
variety of plants known as the Thea. According to the
age of the leaf gathered, there are four well known
grades, Pekoe the youngest, Souchong next, Congou next
and Bohea the oldest. All these are found in the grades
of green or black as the method of curing varies. Green
teas are not fermented, black teas are fermented, and
since fermentation tends to reduce the amount of tannin,
the latter are very generally preferred.

The principal constituents of tea are the alkaloid
caffein, tannin, ash, and essential oil. As a rule more
caffein is found in black teas than in green, and more
tannin and essential oil in the latter.

A proper infusion of tea is made by steeping the leaves
in freshly boiled water (preferably slightly hard) just
below boiling. Five minutes is sufficient to make the ex-
tract, when it will contain the maximum of oil, extract
and caffein and the minimum of tannin. It should now
be poured off the leaves and used. Boiling or long stand-
ing increases the amount of tannin in the infusion, while
it does not materially affect the caffein or extract.

EXPERIMENTS ON TEA.

Make an infusion according to rule given in the text, pour off
the clear liquid, filtering if necessary, and examine the leaves
with a magnifier. Add a few drops of the clear filtrate to a
weak starch solution faintly colored with iodine; if tannin is
present the color will fade. To another portion of the infusion
add a solution of ferric chloride. In the presence of tannin a

176 HOUSEHOLD CHEMISTRY

blue-black ink is obtained. Determine caffein in the balance of
the extract as follows: Add basic acetate of lead as long as a
precipitate appears, filter, wash slightly, reject the residue, add
NaaHPCX solution to the clear filtrate to precipitate excess of
lead as phosphate, filter and wash. Concentrate the filtrate to
small bulk (25 cc.), cool, transfer to a separatory funnel and add
5-10 cc. of chloroform. Mix well, and after settling draw off
the chloroform layer into a weighed porcelain dish and drive off
the solvent over hot water. Cool and weigh. Caffein crys-
tallizes in minute colorless needles, possessing a bitter taste.

After removing the chloroform, evaporate some of the tea
extract in a clean porcelain dish over hot water and note the
large amount of residue, also its color and gummy nature.

Coffee consists of the dried, fermented and roasted
beans of the Caffea arable a — an evergreen shrub. In the
roasting process flavor is increased owing to the conver-
sion of a carbohydrate constituent to caramel, and the
development of caffeol, an oil to which much of the
aroma of coffee is due.

Coffee and tea contain about the same amount of
caffein. In addition the chief ingredients of the former
are caffetannic acid, cellulose, fat, gum, protein, and a
sugar.

French coffee usually contains chicory, the kiln dried
root of the wild endive; the drying operation produces
caramel at the expense of sugar and hence the water
extract is dark in color.

Coffee substitutes are composed of roasted cereals or
breads with or without the addition of ground roasted
coffee. Their extracts may not be entirely free from
caffein and tannin, but in any case will contain less than

HOUSEHOLD CHEMISTRY 177

genuine coffee. The bitter taste and dark color are due
to caramel.

EXPERIMENTS ON COFFEE.

Grind the roasted beans to a fine powder, throw half a tea-
spoonful of the powder into a vessel holding cool water, stir
well, and note whether any color is imparted to the liquid
(chicory).

Moisten i tablespoonful of the powder with cold water, add
i cup of warm water, bring to the boiling-point and boil 2 min-
utes. Filter through paper or cotton and reserve the clear filtrate
for test as follows :

Decolorize a small portion with bone-black and when cold test
for starch with iodine. It should be absent; if present the
sample contains cereal or bread.

Test another portion for tannin (see tea). Determine pres-
ence of caffein (as under tea), using finely ground, well roasted
material, and taking about double the amount used in the case
of tea. Chill some of the clear filtrate; should it turn cloudy,
make further test for dextrin with alcohol.

Make warm infusions (not boiled) of coffee, chicory, and a
blend of the two. Add a small quantity of a saturated solution
of cupric acetate to each and filter. Greenish yellow color indi-
cates pure coffee; red brown indicates chicory; yellow brown
shows a blend of the two.

Examine thoroughly extracted coffee grounds under the
microscope.

Determine quality of the ash.

Notes on Coffee Making.1 — Experiments made to com-
pare the quality and composition of coffee extract pre-
pared from different grades of granulation and by dif-
ferent methods lead to the following conclusions :

1 Taken from the Tea and Coffee Trade Journal, Dec., 1913.

HOUSEHOLD CHEMISTRY

1. The finer the granulation the stronger the extract.
The structure of the coffee granule appears to be such
that fine grinding breaks down minute compartments,
which yield increased flavor and color to the infusion.
For example:

Coffee of medium granulation, sifted through a No. 6
sieve, gave 25 per cent, efficiency.

The same coffee, not sifted, 50 per cent, efficiency.

Pulverized coffee, 100 per cent, efficiency.

Therefore, one part of the last will be equal to four
parts of the first or two of the second.

2. Fresh granulation is essential. Coffee rapidly de-
preciates in flavor.

3. Boiling water is twice as efficient in making the ex-
tract as water under boiling, e. g., at about 150° F.

4. The principal extraction of value takes place the
instant the water boils. If boiling is continued the coffee
changes color and becomes muddy, because the coarse
fibrous shell is broken down and yields undesirable ele-
ments to the infusion. Medium granulation is necessary
in making a clear boiled coffee.

5. The use of egg in clarifying is not recommended, as
it does not improve the flavor. It is better to strain off
the liquor.

The methods of making introduced in the tests were:
Boiling. — Boiling water poured on coffee and the in-

fusion allowed to boil for a few minutes.

Steeping. — Coffee placed in cold water, brought to a

boil, and immediately strained off.

HOUSEHOLD CHEMISTRY

179

Percolating. — In a coffee percolator.

Filtration. — Boiling water was made to drip slowly and
steadily through pulverized coffee in a muslin bag.

Scalding. — Coffee was added to actively boiling water,
vigorously stirred for 30 seconds and the infusion filtered
immediately.

The composition of the infusions was found to be as
follows :

Per cent,
extract

Caffein
Grains per
cup

Caffetannic
acid
Grains per
cup

I.

2.

3-

4-
6.

9-

Boiling (Med. Gran.) .
Boiling (Pulv ) • • • •

2.63
2.76
2.42

1.85

1.86

1.51
1.99

2.58
3-72
0.58

i 75
2.86
2.91

2.22
2-35
2.92

2-35
2.dl

2-35
2.21
2.90
0.29

1.81

2 31

Steeping ( Pulv )

Percolating (3min.) ..
Percolating (5 min. ) • •
Filtration (Pulv. )
Sraldinir (Med A. .

ing

From the above, it will be seen that :

1. Boiling yields the greatest amount of extract, and
a relatively high amount of caffein and caffetannic acid.

2. Steeping yields a lower amount of caffein than (i),
but about as much caffetannic acid. With medium gran-
ulation, the least amount of caffein is given.

3. Filtration gives less extract and less acid.

4. Scalding is intermediate between filtration and boil-
ing.

i8o

HOUSEHOLD CHEMISTRY

5. Percolating gives a low extract but high acid and
high caffein. The reason is that the water in a perco-
lator does not boil over the coffee, but passes over by
force of condensation, at a temperature seldom above
150° F. Hence its power of extraction is low, but its
acid and caffein content will be relatively high, as these
bodies are soluble in cold water. Caffetannic acid is a
hindrance to digestion.

A second series of tests showed the following :

Caffein

Caffetannic

Extract

Grains per
cup

acid
Grains per
cup

United CMeA }

2 60

2 /17

•«47

*»44

Steeped ( Med )

2 1O

o 80

2 40

Percolated (Fine) (3 min. )

1.85

2.86

2.21

Percolated (Fine) (5 min.)

1.86

2.91

2.90

Filtered (Pulv.) (>£Quan.)

1.03

1.47

0.19

The conclusion reached in the article quoted is that on
the whole the filtration method is the best to employ, since
it uses the coffee in the most efficient form and water
at its most efficient temperature ; the flavor of the infusion
is superior; it is almost tannin free, and contains on an
average about il/2 grains of caffein per cup.

Chocolate and Cocoa, — These products are made from
the fermented and dried seeds of the fruit of the Theo-
broma cacao, which resembles the cucumber. After dry-
ing and husking, the seeds yield two halves called "nibs."

The nibs are ground to a fine powder under hot rolls,
which melt the large quantity of fat (cocoa butter)

HOUSEHOLD CHEMISTRY l8l

present and produce a liquid mass. If this is allowed to
run into shallow molds and cooled, the product is called
chocolate or bitter chocolate. Sugar and vanilla extract
are often added to the liquid before cooling, producing
sweet or edible chocolate.

If the fluid mass of ground nibs is pressed to remove
fat and the remainder is cast in molds and afterward
ground, the product is called soluble cocoa. Alkali in
small amount is frequently used in the effort to make the
cocoa more soluble, but this is a fallacy.

The principal alkaloid in the cocoa bean is theobromine.
Caffein is present in small amount.

Cheap grades of cocoa contain considerable quantities
of starch and ground cocoa shells.

EXPERIMENTS ON CHOCOLATE AND COCOA.

Boil some of the finely ground mass with water, filter while
hot and reserve both filtrate and residue for test.

Tests on Filtrate. — For starch, dextrin, sugar, protein matter
and soaps.

Tests on Residue. — Dry and extract fatty matter with gasoline.
Examine extracted residue under the microscope for fiber. De-
termine quality and amount of ash.

CHAPTER XIII.

FERMENTS AND PRESERVATIVES.

The organisms which cause the most common changes
in our food materials are generally known as yeasts,
lactic acid and vinegar ferments. Their spores are
present in all house dust. These organisms are distin-
guished by the fact that they operate in presence of air,
under widely varying temperature conditions, and give
off no disagreeable odors, while their products are non-
poisonous. It is true that putrefactive bacteria play
some part in the preparation of our food, notably in
meats and cheeses, but great care must be observed that
the process is kept under strict control and allowed to
proceed only to a limited extent. The activities of these
various organisms are due to enzymes secreted by their
cells.

Yeast Fermentation. — This type of fermentation is
typically alcoholic. The food chosen for the growth of
the yeast organisms is mostly carbohydrate material,
which is decomposed by enzyme action to alcohol and
carbon dioxide as the principal products. The by-prod-
ucts are extremely numerous, and include succinic acid,
glycerol, and traces of esters, aldehydes and complex
alcohols. The expression C6H12O6 ~-> 2C2H5OH -f 2CO2
is therefore merely general for yeast action.

In ordinary yeast the enzymes acting on carbohydrate
material are maltase, invertase, and zymase. There is
evidence that phosphates, such as are present in yeast

HOUSEHOLD CHEMISTRY 183

cells, are necessary to fermentative changes, as added
phosphates greatly stimulate fermentation and enter into
combination with monosaccharid material as a hexose-
phosphate.

Due to the specific action of the enzymes present,
starch and lactose are not acted upon directly by ordinary
yeast; maltose is changed by maltase to glucose; cane
sugar is hydrolyzed by invertase, and zymase completes
the alcoholic fermentation of the monosaccharid prod-
ucts. Different yeasts have different fermenting action,
e. g., S. fragilis, found in kefir, has a lactose enzyme.

Yeasts in general have their optimum activity between
68° and 90° F. ; the maximum growth temperature for
many varieties is about 105° F. In the moist condition
coagulation takes place at lower temperatures than in the
dry. Yeasts are killed more or less quickly from m° to
140° F., with moist heat. Sterilization with dry heat
necessitates long continued high temperatures, or inter-
mittent sterilization. For pasteurization, it is well to
maintain for some time the lower temperature employed,
to insure uniform heating of the mass. Yeasts are not
easily destroyed by cold unless exposed to very low tem-
perature for long periods.

The rate of fermentation increases with concentration
of the sugar up to a certain limit, then decreases with
further concentration. When 15 per cent, of alcohol has
been formed the action ceases, even though the mass con-
tains unchanged carbohydrate.

Lactic Acid Fermentation. — The organisms capable of
producing this form of fermentation are numerous, and

184 HOUSEHOLD CHEMISTRY

operate on various forms of carbohydrate material.
They have been found in milk, beer, distiller's mash,
sauer kraut, and other substances. The forms most com-
monly occurring in milk are the Streptococcus lacticus,
and a similar organism, Bacterium lactis acidi, which
hydrolyze lactose, and convert the resulting glucose almost
entirely into lactic acid: C6HnO6 — •> 2C3H6OS,
with no gas formation. Another organism well known
for its value in preparing sour milk is B. bulgaricum. It
hydrolyzes lactose and ferments about 92 per cent, of
both products — galactose and glucose — to lactic acid so
that the total amount formed is much greater than with
the organisms described above. These ferments are not
easily destroyed by cold but do not act below 50° F. and
continue their work up to 130° F., being most active at
110° F. Conditions for sterilization and pasteurization
are similar to yeasts.

These organisms represent the true lactic fermentation,
in which the by-products are almost negligible. A modi-
fied lactic fermentation is produced by groups of in-
testinal origin. The products of these are lactic and
other acids, alcohol and gases — lactic acid forming less
than one-half of the total.

Salt-rising bread1 and sour dough bread are prepared
by a method of spontaneous fermentation. The organ-
isms producing fermentation probably vary, but in some
instances are those which develop lactic acid and gas
from sugar. When corn meal has been used in the fer-

1 See Buchanan : Household Bacteriology, and The Baker's
Review, August, 1911, to March, 1912.

HOUSEHOLD CHEMISTRY 185

menting batter, it is probable that the gas mixture (hy-
drogen and carbon dioxide) is produced by the Bacillus
Coll. A dried form of ferment is now sold for this pur-
pose.

Acetic Acid Fermentation. — The production of acetic
acid from alcohol is a type of bacterial action well known
in everyday experience. The souring of wines and the
production of vinegar are illustrations of the activities of
this organism. The ferment, commonly known as
"mother of vinegar," carries oxygen from the air to the
alcohol, the oxidation resulting in acetic acid :

CH,CH2OH -f O2 — CH3COOH + H2O
It acts on all weak alcoholic liquids of 10 per cent, and
under. The temperature conditions are much the same
as for lactic acid (5o°-no° F.). Fermentation ceases
when 5 per cent, of acid has been produced. Conditions
for sterilization and pasteurization are similar to yeasts.

Butyric Acid Fermentation. — Important fermentative
changes producing butyric acid are brought about by the
action of many bacteria. Two types of these organisms
are recognized:

(1) The non-motile butyric acid bacillus, found in
milk and in the soil. It is an anaerobic form which fer-
ments sugars, starch, and under some conditions lactic
acid, the products being butyric acid, lactic acid, hydro-
gen, and carbon dioxide. It liquefies gelatin.

(2) The motile butyric acid bacillus, found in soil,
water, and cheese. It is anaerobic, does not liquefy gel-

l86 HOUSEHOLD CHEMISTRY

atin, and has a chemical action on carbohydrates similar
to the non-motile form.

Other forms are known, of a pathogenic order, which
act upon both carbohydrates and proteins.

EXPERIMENTS.

i. Fermentation of Carbohydrate by Yeast. — Dissolve a con-
siderable quantity — about 150 grams — of commercial glucose or
of molasses in I or 2 liters of water in a good sized distilling
flask. Dissolve one-fourth of a yeast cake, add to the solution,
warm to 25° and keep in a warm place until fermentation ceases.
Distil over a water-bath, noting the temperature at which the
distillate passes over, and test the latter for alcohol by burning
a portion and by the iodoform reaction.

Yeast — Temperature Experiments. — Prepare four 6-inch test
tubes with perforated corks, bearing tubes bent in the form of
the inverted letter J. Fill three of the tubes with a mixture,
prepared from one-half a yeast cake, one-half tablespoonful of
molasses and a cup of water. Fill the fourth with the same
preparation filtered through absorbent cotton. Allow tubes Nos.
i and 4 to stand, while No. 2 is subjected to a temperature of
32° F. (produced by a mixture of pulverized ice and salt) for
15 minutes. No. 3 is boiled for 2 or 3 minutes. Now place the
four pieces of apparatus so that the delivery tube of each reaches
to the bottom of a test tube containing about 2 inches of clear
limewater, and allow them to stand for at least 2 hours in a
warm place (90° F.). At the end of this time examine each
tube of limewater, first for a precipitate, and second with litmus
paper. Finally examine the liquid in the fermentation tubes,
noting its odor and general properties.

For the action of yeast on soluble carbohydrates, see p. 97.

Lactic Acid. — To about 6 ounces of pasteurized milk contained
in a small flask, add i tablespoonful of the liquid obtained by
dissolving one lactobacilline (Metchnikoff) tablet in half a cup
of tepid water. Mix well and keep at 100° F. for 36 hours.

HOUSEHOLD CHEMISTRY 187

Carefully observe all changes taking place and compare with the
well known buttermilk.

Acetous Fermentation.— Make a weak solution of alcohol in
water (5 parts of alcohol to 20 parts of water) and test with
litmus paper; if acid, neutralize with a weak solution of sodium
carbonate and test a small portion with potassium iodide and
potassium hydroxide; heat — the odor of iodoform shows the
presence of alcohol.

Divide the balance of the solution into two equal parts, pour
one into a shallow dish and place the other in a well-corked
bottle. After the solutions have stood for a week, test with
litmus paper, and also by adding alcohol and warming gently.
Note the peculiar odor of ethyl acetate — odor of hard cider — in
the first case but not in the latter. Explain.

Expose a small quantity of beer to the atmosphere for several
days; subsequently examine for acidity with test paper and for
acetic acid with alcohol. From the results of these experiments
explain why bottled weak alcoholic beverages keep sweet.

Butyric Fermentation. — Neutralize some sour milk with chalk,
add a little decaying cheese, and allow to stand for some hours.
The butyric ferment in the cheese acts on the lactic acid in a
neutral medium, as follows:

2CHSCHOHCOOH »~* C8H7COOH + 2CO, + 2H2

Note the growing acidity and odor of the milk.

All foods are subject to the attack of bacteria and in
consequence their value is very generally seriously im-
paired. Methods for prevention of these changes have
been used from the earliest times and are known as
preservation.

At least two general types of process are in common
use, viz., physical and chemical. To the first class belong
such methods as drying, cooling, and canning. These
processes are applicable to all kinds of foods, possess
high efficiency and make very slight changes in flavor,
13

l88 HOUSEHOLD CHEMISTRY

appearance and composition. Unfortunately, food ma-
terials preserved in any of these ways will change very
rapidly with a slight variation of physical conditions,
hence the effects are not permanent. The second class
involves such change of chemical conditions that no mat-
ter what physical changes may occur, decomposition can-
not take place. The results are permanent but are ac-
complished at the expense of flavor, appearance, etc.

So general has the use of chemical preservatives be-
come that a brief discussion of the subject seems neces-
sary. The best known and, as generally conceded harm-
less, are: alcohol, vinegar, sugar, and salt (NaCl). With
the exception of vinegar (acids generally being inimical to
bacteria) the action seems to depend on making the pro-
tein matter present insoluble ; hence we find the quantity
of the preservatives important. Well known operations
are as follows:

Alcohol — 50 per cent. "Brandying."
Salt — dry or supersaturated solution "Pickle."
Sugar — syrup — solutions of 25 per cent, or more.
Less well known methods accomplish similar results
by using very small, in some cases minute proportions, of
other chemical agents; but the actual chemical operation
can only be surmised in most cases. Included in this list
are: borates, fluorides, sulphites, peroxides, formalde-
hyde, benzoates, salicylates and creosote. It may be as
well to observe that the use of spices, for instance in
mince meat, is certainly parallel with benzoates and
salicylates.

Boric acid, borax and borates are efficient in small

HOUSEHOLD CHEMISTRY 189

quantities — as low as I per cent. Their use in preserving
meats is not permitted at present in the United States.

Sulphites can not now be used for giving cut meat a
red appearance.

It has not been proved that sodium benzoate is danger-
ous in the amounts used for food preservation, and it is
allowed under the Food and Drugs Act, provided the label
states the fact. Salicylic acid is not allowed.

Wood tar creosote is very efficient as a non-poisonous
preserver of meat.

EXPERIMENTS.

Alcohol and vinegar are first separated by distillation and then
identified by well known methods. Sugar and salt may also be
determined by diluting, filtering, and testing the clear filtrate.

Borates. — Ash some of the substance, cool, make strong water
extract, filter if necessary and neutralize with dilute HC1. Dip
a strip of turmeric paper in this liquid, remove and dry by steam
heat. (This may be accomplished by wrapping the moist paper
around the upper part of a test tube partly filled with water
and boiling gently.) The paper turns pink on the edges.

Or moisten the ash in the dish with alcohol, add 8 to 10 drops
of glycerin, mix well with a glass rod and ignite the mass with
a match or Bunsen burner. Note the yellow flame with a green
edge, characteristic of borates.

Fluorides. — Mix the liquid or solid mass with an excess of
limewater, evaporate to dryness, ignite, cool and make the etch-
ing test.

Sulphites. — If present in quantity, they are distinguished by
their odor and taste, "sulphur match," especially on warming.

For small amounts of sulphites, mix with bromine water, boil
off excess and test for sulphates. Sulphates may be present in
the original liquid, in which case precipitate by BaCU, and HC1,
filter and use the clear filtrate as above.

Formaldehyde. — See page 198.

190 HOUSEHOLD CHEMISTRY

Benzoates. — Carefully mix liquid substance with one-tenth of
its volume of chloroform and a few drops of commercial sul-
phuric acid. Avoid violent shaking (mix with a rotary motion).
Allow the mixture to remain quiet until chloroform layer sepa-
rates. Remove some of this layer with a pipette and evaporate
it in a clean porcelain dish over hot H2O. Note the flat crystal-
line plates of benzoic acid, which give off a pungent odor on
heating. Examine the original mixture in the flask, note any
violet color between layers of acid liquid and chloroform. This
indicates salicylic acid.

Both benzoic and salicylic acids are not present in the same
liquid.

TESTS FOR PURITY OF CERTAIN FOODS.

Sanitary Condition of Milk.— The presence of a large number
of bacteria in milk indicates staleness or an insanitary condition.
The following test will give some indication of its purity: First
sterilize all utensils used by keeping in boiling water */2 hour.
Warm I pint of milk to body temperature and add one junket
tablet which has been dissolved in I tablespoon of cooled boiled
water. Stir until thoroughly mixed and allow to stand quietly
until the milk has clotted. Cut the curd in cross-sections with
a knife and carefully pour off the whey. From time to time,
draw off the whey as it accumulates. When the curd is com-
pact, cut it with a knife and observe its condition. If it is firm
and smooth with but few holes, the milk does not contain an
abnormal number of bacteria. If the curd has a spongy appear-
ance, bacteria are present which have produced gas. Place a
tablespoon of the curd in water ; if it sinks, the milk is compara-
tively clean; if it floats, the milk is stale or in an insanitary
condition.

Formalin in Milk. — See page 165.
Genuine Butter. — See page 139.

Coal Tar Coloring in Butter, etc.— i. The custom of coloring
butter is very largely practiced in the United States. Vegetable
dyes, such as annatto, have been employed in the past, but coal

HOUSEHOLD CHEMISTRY IQI

tar products (anilin dyes) are now quite frequently used. Coal
tar yellow may be detected by the following experiment: Into
a weak solution of alcohol, put I teaspoon of butter, a small
amount of cream of tartar, and bits of white silk or wool. Boil
the mixture. If coal tar coloring is present, the samples will
be dyed.

2. Melt a teaspoonful of butter in a test tube at low heat. Add
an equal volume of Low's reagent (mix 4 parts CH3COOH,
I part HaSCX) ; shake well, heat nearly to boiling, and set aside
to separate into layers. The acid layer will be colored red if
azo dyes have been used. Pure butter gives a faint blue tinge.

Annatto. — Place about 100 cc. of milk in a cylinder, make alka-
line with sodium carbonate solution, insert a long strip of heavy
white filter paper and allow to stand in a dark place for about
12 hours. Withdraw the paper, wash gently in running water
and observe against a fresh piece of the same kind of paper. If
annatto is present, the paper will have taken up some of the
color. Prove by dipping the strip into a solution of stannous
chloride. It becomes pink.

Alum in Food Products.— Make water solution and follow
method under Baking Powders, page 174.

Copper Compounds in Canned Goods. — As a rule, coloring matter
is not added to domestic goods. Imported varieties, as green
peas, having an intense color, usually have copper added in
small amounts. It may be detected by adding a few drops of
hydrochloric acid to a portion of the material and dropping in
a bright steel nail or the blade of a knife. If copper salts are
present, a reddish color will appear on the steel.

Purity of Olive Oil.— See Halphen's Test, page 138.

Purity of Extracts.— Vanilla.— ( a) Vanilla extract shows a
nearly colorless foam on shaking; in case vanillin has been used
the foam will be colored due to the addition of caramel for the
purpose of imitating the vanilla color.

(fe) Leach's Test, — To 40 cc. of the sample add an equal
volume of normal lead acetate (dissolve 189.5 grams of
Pb(C3H3O2)», 3H2O in water and make up to i liter). If a

IQ2 HOUSEHOLD CHEMISTRY

precipitate settles the vanilla is pure ; vanillin gives no precipitate.
Lemon Extract. — Test by adding a few drops of the extract
to water. The true lemon oil is insoluble in water, and a milky
appearance results. Artificial lemon extract gives a clear water
solution.

Saccharin. — This substance may be added to canned products
in place of sugar. It is a coal tar product having several hun-
dred times the sweetening power of cane sugar. To determine
its presence shake 15 or 20 cc. of the suspected liquid in a flask
with an equal volume of chloroform. Saccharin is soluble in
chloroform ; while sugar is insoluble. With a medicine dropper
remove some of the chloroform which has settled to the bottom.
By gently heating in a porcelain dish, evaporate the chloroform.
Taste the residue; if sweet, saccharin is present.

Freshness of Eggs.— Candling is one of the methods most fre-
quently used. In a darkened room hold an egg between the eye
and an artificial light. A fresh egg should appear unclouded,
homogeneous, and almost translucent. If dark spots are found,
it is stale. A rotten egg appears dark colored.

Against the larger end of a fresh egg between the shell and
the lining membrane, a small air cell should be distinctly visible.
In an egg which is not perfectly fresh, this space is filled with
the egg substance, unless the egg has been stored with the large
end up.

Salt solution test: As the density of an egg decreases by the
evaporation of moisture, its freshness may be approximately
estimated by placing it in brine. Prepare the salt solution by
dissolving 2 ounces of salt to I pint of water. Immerse the egg
in the solution. A perfectly fresh egg will sink; if several days
old, it will swim just immersed in the liquid; if stale, it will
float on the surface.

Shake an egg, holding it near the ear. The contents of a fresh
egg should not move. If a slight movement can be detected, it
is somewhat stale ; if it rattles, the egg is spoiled.

Open the egg and observe the odor and taste. If there is a

HOUSEHOLD CHEMISTRY IQ3

tendency for the white and yolk to run together, the egg is not
fresh, or the hen has been improperly fed.

Coffee. — See Experiments, page 177.

Gelatin in Ice Cream. — Page 166.

Vinegar has been very largely subject to substitution and imi-
tation. The best varieties on our market are cider, wine, and
malt vinegar. Substitution may be detected by slowly evapo-
rating almost to dryness ^ cup of vinegar in a small evaporating
dish and examining the warm residue. If there is a distinct
odor of baked apples, it is cider vinegar; of grapes, it is wine;
and of malt, the product is malt vinegar. Distilled vinegar gives
a burnt sugar odor; no residue indicates synthetic vinegar.

CHAPTER XIV.

DISINFECTANTS AND DISINFECTION.

These terms apply to the destruction of bacterial or-
ganisms and their spores. Some confusion of ideas
exists with regard to the respective action of disinfec-
tants and antiseptics. A disinfectant is a germicide; an
antiseptic retards or prevents bacterial activity. A de-
odorant simply absorbs or covers up noxious vapors.

Physical Methods of Disinfection or Antisepsis. — Sun-
light.'— The direct rays of the sun are powerful enemies
of bacteria, the bacillus of tuberculosis, for example, being
killed by sunlight.

Dry Air. — Dry air arrests the activities of bacteria by
removing conditions of moisture favorable for their
growth, and oxidizes the products of their action through
the work of aerobic organisms in the air.

Cold Storage. — This is an efficient temporary method
of inhibiting bacterial activity. It should be understood
that freezing and cold storage are not the same. In
freezing, the expansion of the ice crystals disrupts the
structure of food and leaves it open to attack. Food
that has been frozen should therefore be consumed as
soon as possible after thawing.

Pasteurisation. — Bacteria likely to be present in impure
milk are killed by a temperature of 60° to 70° maintained
for 20 minutes to I hour, according to the temperature
employed. The organisms which escape are compara-
tively harmless in effect.

HOUSEHOLD CHEMISTRY 195

Boiling. — Typhoid and tuberculosis bacteria are killed
by boiling for I minute. Drinking water and milk are
likely to be sterilized by this treatment. To destroy the
spores of some other forms of pathogenic bacteria, boil-
ing must be repeated on two or three successive days.

Some Common Antiseptics. — Salt, sugar, spices, vinegar,
and creosote have considerable efficiency as antiseptics.
The power of salt, sugar, and vinegar to inhibit the action
of bacteria depends upon the strength of their solutions.

Chemical Means of Disinfection. — Mercuric chloride,
or corrosive sublimate, is one of the most powerful of
germicides. Its use is limited, partly because it is a
violent poison, partly by its tendency to form a precipitate
with many inorganic and organic substances, such as hard
water, alkalies, protein bodies, etc. A solution of one
part of mercuric chloride in one thousand parts of water
is commonly employed.

Carbolic Acid. — This is frequently used in very dilute
solution as an antiseptic wash, as a powerful antiseptic in
a strength of I to 400, or as a germicide in stronger
solution, such as 5 per cent.

Formaldehyde. — Formaldehyde is antiseptic in weak
solution, and germicidal in the 40 per cent, solution called
formalin. For room disinfection the formaldehyde gas
is used, produced by lamps which pass methyl alcohol
vapor and air over hot oxidized copper, or by heating
paraform. This substance is a solid polymer of form-
aldehyde, which gives off the gas when heated. Form-
aldehyde is also produced from formalin heated under

196 HOUSEHOLD CHEMISTRY

pressure, or treated with dehydrating agents to cause an
evolution of the gas.

Sulphur Dioxide. — This is a powerful disinfectant, but
has the disadvantage of being also a strong bleaching
agent, and therefore cannot be used in the presence of
colors. The gas is produced by burning sulphur, com-
monly in the form of a sulphur candle. It is irrespirable,
and has produced fatal results when in the proportion of
about 5 per cent, in air. To do away with the necessity
of using fire to produce sulphur dioxide, its solution in
water as sulphurous acid is frequently used. This acid
is unstable, and when exposed to the air gives off sulphur
dioxide and water.

Copper Sulphate. — This compound ranks next to mer-
curic chloride in antiseptic power. It is soluble in four
parts of water, and in I per cent, solution is disinfectant ;
in weak solution, e.g., o.i per cent., it is antiseptic in
most cases.

Zinc Chloride is strongly antiseptic and disinfectant,
and is useful for drains. A solution of I to 5 per cent,
is employed for ordinary antiseptic purposes. Zinc oxide
is much used in the preparation of cold creams and oint-
ments, and is a mild antiseptic.

Hydrogen Peroxide is a powerful oxidizing agent, as it
decomposes into water and nascent oxygen. It has a
bleaching action on fabrics, but is not as destructive to
the material as are Javelle water or bleaching powder.
As a disinfectant it is comparatively slow in its action,
but the evolution of oxygen is hastened by the addition
of a small amount of an alkali, such as borax, to the

HOUSEHOLD CHEMISTRY

solution. In dilute solution hydrogen peroxide is non-
poisonous.

''Chloride of Lime" or Bleaching Powder. — So-called
chloride of lime, used for disinfecting purposes, is cal-
cium hypochlorite, Ca(ClO)2. A similar compound, so-
dium hypochlorite, is known as Javelle water. The action
of both depends upon the available chlorine they contain,
which when set free unites with water to form eventually
hydrochloric acid and nascent oxygen. The carbon
dioxide of the air, or other acid present, is necessary to
bring around the reaction. Using acid :

Ca(ClO)2 -f 2HC1 — CaCl2 + 2HC1O
2HC1 + 2HC1O — 2H2O + 2C12
C12 -f H2O — > 2HC1 + O.

Both hypochlorites are strong bleaching agents and are
especially destructive to wool and silk fabrics. Cotton
and linen materials are not seriously affected, but should
be rinsed free from bleaching powder or Javelle water if
these are used for disinfecting clothes. The latter solu-
tion is better for this purpose. Bleaching powder is
often used for drains in about 10 per cent, solution.

Washing Soda. — In the strength used in the laundry,
washing soda has little antiseptic effect, but is efficient in
about 2 per cent, hot solution as a disinfectant for wash-
ing floors and walks, milk cans, etc.

Soap has considerable antiseptic power. So-called dis-
infectant soaps have little advantage over ordinary pure
soaps unless the proportion of disinfecting ingredient is
high, and it is in readily soluble form.

198 HOUSEHOLD CHEMISTRY

Tests for Disinfectants.

On account of the small quantities of material usually
employed, many of the ordinary analytical tests fail to
give conclusive results. Hence the following methods
are suggested, as being more reliable in the majority of
cases.

Mercuric Chloride. (Found usually in one or two parts, or
less, per thousand.) — To 50 cc. of the solution in a large test
tube add a few cc. of a mixture of equal parts of weak potassium
iodide and ammonium chloride solutions (each I per cent.) and
immediately 2 or 3 drops of caustic soda. A yellow color or
brown precipitate developing after a few minutes' standing indi-
cates mercury. It will be noticed that this test is a reversal of
Nessler's test.

Carbolic Acid. — To the clear liquid add bromine water in slight
excess and immerse in hot water until all odor of bromine is
dissipated. A white bulky precipitate of bromphenol indicates
carbolic acid.

Formaldehyde is best indicated by the violet band appearing
as a zone when the liquid containing the aldehyde is carefully
poured upon a large volume (10 cc.) of commercial concentrated
sulphuric acid (oil of vitriol) held in a test tube. The color is
due to ferric salt always present in the crude form of the acid.

Sulphur Dioxide or Sulphites.— Indicated by warming the acidi-
fied (HC1) solution — ian odor of burning sulphur is apparent.
Or by adding barium chloride to the acidified solution, boiling,
and filtering off the first precipitate (a precaution necessary due
to the presence of sulphates), finally adding a few drops of
nitric acid to the clear filtrate and boiling again until oxides of
nitrogen and chlorine are expelled. A white precipitate of
barium sulphate remains, insoluble in hydrochloric acid.

Copper Sulphate. — Indicated by a deep blue color on adding
ammonium hydroxide in excess, or by a reddish brown precipi-
tate in potassium ferrocyanide solution acidified with acetic acid.

HOUSEHOLD CHEMISTRY 1 99

Ferrous Sulphate. — Indicated by a deep blue precipitate in
contact with dilute potassium ferricyanide solution, which decom-
poses on addition of sodium hydroxide and leaves a brownish
residue.

Permanganates. (Alkaline potassium or sodium.) — Impart a
pinkish color to the liquid even in dilute solution. The color is
quickly discharged on adding a mixture of dilute sulphuric and
oxalic acids and warming, or by a few drops of fresh ferrous
sulphate solution acidified with dilute sulphuric acid.

Hydrogen Peroxide.— Indicated by the deep blue shade imparted
to ether when in contact with an acidified mixture of potassium
dichromate and peroxide.

Bleaching Powder ("Chloride of Lime"). — Sets free the halogen
from potassium or sodium iodides. If chloroform is added the
iodine dissolves in it with a violet color. In the presence of
starch, the iodide of starch (blue color) is formed.

CHAPTER XV.

CLEANSING AGENTS.

The number of compounds put on the market for
household use in cleansing and allied operation is con-
stantly increasing, and in many cases extravagant claims
are made with regard to the efficacy of the preparations.
The public is led to believe that each one represents the
discovery of a new and powerful detergent. As a matter
of fact, analyses of these preparations show that they
are merely variations in combination of a few well known
cleansing agents. A general classification of cleansers
and similar compounds reduces them to a few principal
groups :

1. Soaps and soap powders.

2. Scouring powders.

3. Metal polishes.

4. Bleaches and stain removers.

5. Grease solvents.

6. Bluings.

Soaps and Soap Powders. — As shown in Chapter IX,
soaps are a product of the saponification of a fat by an
alkali. Sodium or potassium hydroxide is commonly
used. The type formation of the soap is as follows :

(HOH)

(1) Fat »-*• fatty acid -|- glycerol.

(2) Fatty acid -f alkali »-»> soap.

It will be seen that glycerol is a by-product. It is
recovered in the commercial method of soapmaking, a

HOUSEHOLD CHEMISTRY 2OI

process which gives the market its chief supply of this
commodity.

The Cleansing Action of soap is both physical and
chemical. Its solution in water acts as an emulsifying
agent, loosening and removing dirt particles. Chemically,
soaps are salts of a strong base and a weak acid, and as
such dissociate in water with some hydrolysis, e, g,:

C17H35COONa + HOH — C17H35COOH + NaOH.

The alkali set free may form additional soaps with free
fatty acids present in the greasy impurities of the article
to be cleansed.

Soap powders contain dry pulverized soap, together
with an excess of sodium carbonate in the hydrated form.
They may or may not contain insoluble mineral matter —
clay, sand, etc. — and trifling amounts of borax.

Manufacture of Soap. — Two classes of water-soluble
soaps are recognized — hard, or soda, and soft, or potash
soaps. In the former the harder fats and non-drying
oils are used as a rule; for the latter vegetable drying
oils and marine animal oils are utilizable. In the manu-
facture of hard soaps two methods — the cold process or
boiling — may be employed. The hot process is the usual
commercial method, as the soap produced is more apt
to be uniform in appearance and quality, and glycerol
can be recovered as a by-product. The cold process gives
a simple and quick method for household use, and if
operated with intelligence gives a good neutral soap,
which contains the glycerol.

202 HOUSEHOLD CHEMISTRY

Boiled Soap. — The saponification process is divided
into at least four stages, although a number of interme-
diate stages called "washes" are frequently introduced to
remove impurities.

The four changes are known as :

Stock change.

Rosin change — where no rosin is used this change

is replaced with a wash.
Strength change.
Finish.

Stock Change. — The required amount of mixed tallow
and grease or oil are melted together in large iron kettles
or tanks by the aid of steam coils, the lye is added and
the whole mass boiled until it is saponified ; at this stage
the mass of boiling soap has a peculiar smooth appear-
ance called "closed." Pickle is now added, until the
contents of the kettle separate into small broken grains;
this stage is called "open or grained." Heat is turned
off and the kettle allowed to cool; when cold there will
be two layers, the upper one of soap, floating on the salt
lye — this latter is called "spent lye" and should be almost
neutral. From it glycerin and salt may be extracted.
The spent lye is then drawn off from the bottom of the
kettle, leaving the soap for the next operation. If no
rosin is to be used the "wash change" takes place at this
point; this consists in adding water, boiling to a "close"
and then salting out and settling as before; the wash
lye is worked up for salt and glycerin.

Rosin Change. — Soap from previous operation receives

HOUSEHOLD CHEMISTRY 2O3

an addition of fresh, strong lye, is heated to boiling and
the rosin in lumps thrown into the kettle; only just
enough lye to saponify the rosin is used; the amount of
rosin varies but usually equals the weight of the tallow
and grease. Boiling is continued until rosin is saponified,
and then pickle is added to grain; the kettle stands to
cool; the rosin fat soap rises as before and the rosin lye
is drawn off and worked for salt and traces of glycerin.

Strength Change. — The rosin fat soap is now boiled
with fresh strong lye until saponification is complete.
It is always found that small amounts of fat and rosin
escape saponification in the earlier stages unless these are
unduly prolonged. The kettle is cooled and the soap
which has been grained or open condition throughout
this operation (due to strong lye) rises; when cold the
strong lye is drawn off and used to start the saponifica-
tion in the stock change. This lye is often mixed with
that coming from the strength change.

Finish. — The thoroughly saponified grained soap still
contains strong lye and many impurities; and this is
removed by melting and adding water carefully until the
soap "closes," or loses its grained structure. The kettle
is allowed to cool very slowly, being kept perfectly quiet
for at least 48 hours. During this time three layers are
formed, the upper consisting of pure soap, -the interme-
diate of impure dark soap called "nigre," which may be
sold as such or bleached in a subsequent operation, and
a very small amount of strong alkaline lye called the
nigre lye, which is generally thrown away.
14

204 HOUSEHOLD CHEMISTRY

The finished soap is either run into iron box moulds,
stirred well, and allowed to cool and set thoroughly, and
then cut; or is run into a "crutcher" or mixing machine,
where various additions, such as sal soda, silicate, sa-
ponified rosin, etc., are made. From this machine the
mixture is run into frames, cooled and cut.

Half Boiled Soap. — Much of the ordinary toilet soap is
made by this process, which is as follows :

The requisite quantity of fat, tallow, grease, cotton-
seed or coconut oil is heated gently in a jacketed steam
kettle, enough very strong lye usually mixed; potash or
soda is gradually added and stirred vigorously ; the oper-
ation is complete when the hot soap is clear and will run
in long strings from the trowel or starrer. The mixture
is now ladled into frames and allowed to cool and set.
When cold it is removed from the frame, cut into strips,
dried, chipped, milled between stone rollers. In the mill-
ing operation, coloring matter and perfumery are added,
although for cheap soaps these additions may be made in
the kettle after saponification. After milling, the soap
goes through the "plotter," which forms it into long bars
and cuts these into convenient lengths for pressing. It
will be noted that the glycerin remains with the finished
soap in this process. The best toilet soap is made by the
full-boiled process.

Average Analyses. — The average compositions of a
white laundry soap of good quality and a yellow soap
containing rosin are given on the next page for compar-
ison:

HOUSEHOLD CHEMISTRY

205

Rosin soap
per cent.

White soap
per cent.

Water

TC_OC

J5 ^5

Oc 7r

°5-/5

Na CO

35-°

o

•o

100.0

100.0

Use of Rosin. — Rosin is cheaper than soap grease, and
is introduced primarily as a filler. It is properly classed
as an adulterant. By its presence more water can be
incorporated with the soap, hence rosin soaps soften and
waste away rapidly. It is not strictly a detergent, ex-
cept as it aids in making a suds, and its continued use
has a yellowing effect on white fabrics. Based on the
amount of actual soap contained in soaps of this class,
they cost more per pound than a good grade of white
soap.

Cold Soaps. — For the production of a neutral soap by
this process, the correct combining amounts of fat and
alkali must be determined. The mean saponification
numbers of the fats and oils commonly used call for a
proportion of i gram of fat to 0.195 gram of KOH, or
0.139 gram of NaOH, i. e., ratios of 5 : i and 7:1 re-
spectively. Therefore, in practice, 5 units of fat by
weight combine with i unit of caustic potash, or 7 units
with one of caustic soda. This calculation is approxi-

206 HOUSEHOLD CHEMISTRY

mated by taking the combining weights of the inter-
acting substances :

C17H35COOH + NaOH ~- C17H35COONa + H2O.

284 40

Here 284 units of weight combine with 40, giving a
ratio of 7:1.

In round numbers, for 7 pounds of fat, use I pound
of caustic soda, dissolved in water to a suitable bulk.
Crude caustic soda, costing a few cents per pound, can
usually be obtained. The consistency of the fat largely
determines the amount of water which may be incor-
porated; a fat liquid at ordinary temperatures will take
up only about enough to dissolve the alkali, more solid
fats will hold water in amounts varying from one-half
the weights of fat to equal weights of the two.

The process of making cold soap consists in melting
the fat, stirring in the dissolved caustic soda until a
homogeneous, creamy mass is obtained, and setting the
mixture aside in molds to complete the saponification and
harden. Twenty-four hours usually suffices. Some
household recipes are appended, made on the basis of i
pound of fat. To obviate weighing 1/7 of a pound of
the alkali, it is convenient to dissolve a pound in the right
amount of water, and measure out the particular quantity
required.

Laundry Soap. — 1/7 pound NaOH dissolved in suffi-
cient water to make 14 fluid ounces ( i% cups) . Strength
17° Baume.

i pound solid fat melted.

HOUSEHOLD CHEMISTRY 2O/

Emulsion Soap. — Add to the above before it hardens,
3 tablespoonfuls each of kerosene and a strong solution
of washing soda. Stir about 5 minutes longer. Incor-
porate i pint of water for a soft soap.

Castile. — 1/7 pound NaOH made up to % cup with
water. (38° Baume.)
i pound olive oil.

Coconut Oil. — j% pound (full weight) NaOH made
up to i cup.

i pound coconut oil.

(The exact proportions are 5^2 pounds oil to i pound
NaOH.)

By stirring in air with an egg beater, the result will be
floating soap.

Palm Oil. — 1/7 pound NaOH made up to ij4 cups,
i pound palm oil.

Special Varieties — Scouring Soaps. — These are made
by introducing into the soap while in a creamy condition,
a large amount of finely pulverized quartz or other min-
eral matter.

Transparent Soaps. — Such soaps are made by incor-
porating the amount of alcohol required to hold the soap
in a clear solid solution. In some cases the transparency
is produced by the use of sugar, which must be consid-
ered an adulterant.

Liquid soaps are soap solutions containing an excess
of the solvent.

2C>8 HOUSEHOLD CHEMISTRY

Soap Analysis. — For detailed methods, see Chapter
XVI. As a simple means of determining whether a soap
is superfatted or contains excess alkali, apply the follow-
ing tests :

TESTS.

For Free Fat. — Shake a few shavings of the soap in a corked
test tube with cold gasoline, filter into a convex glass and evap-
orate the gasoline over warm water. A greasy residue indicates
unsaponified fat.

For Free Alkali. — Shake a few shavings of the soap in a
corked test tube with warm alcohol (95 per cent.), filter and
add to the clear liquid a few drops of phenolphthalein ; a red
color indicates free alkali. Or, drop some of an alcoholic solu-
tion of phenolphthalein on the freshly cut surface of the soap.

For Rosin. — Put some shavings of soap in a dry test tube and
add about 5 cc. of acetic anhydride. Pour in carefully concen-
trated HaSCX. A red violet color appears if rosin is present.

Scouring Powders. — These are improved forms of the
old crude mixtures of sand and soap, formerly used ex-
tensively for rough cleaning. They now consist of clay
incorporated for absorbent purposes, and pulverized soap,
containing abrasive material in a more or less finely
divided condition. Borax may be present, and at times
clay is partly or entirely replaced by chalk. The common
fault with such preparations is that their use is recom-
mended for general cleaning, but they frequently contain
sharp abrasive particles which make them injurious to
fine metal or porcelain surfaces.

Average analyses of these powders are appended:

Per cent.

Water I- 6

Soap 4-14

Sodium carbonate 0-24

Abrasive material 63-93

HOUSEHOLD CHEMISTRY 2OQ

Metal Polishes. — These polishing agents are on the
market in liquid, paste, and powder forms, also as polish-
ing cloths. Their action in removing tarnishes — oxide,
sulphide or carbonate coatings — depends upon the ab-
rasive effect of pulverized mineral material, the solvent
action of chemicals, or both combined.

The liquid polishes are solutions containing as a rule
one or more of the following ingredients: oxalic acid,
muriatic acid, ammonia, benzine or benzene, and potas-
sium cyanide. These may be combined with pulverized
mineral matter.

Oxalic acid is very effective in dissolving metallic
oxides and carbonates, and is therefore in common use as
a cleanser for brass and other metals. The acid potas-
sium oxalates are similarly used. The metal itself is
liable to be attacked by oxalic acid, which should not be
used in too strong solution for nickel-plated faucets, etc.

The cleansing effect of muriatic acid is similar to that
of oxalic, and can be produced in the household by using
a mixture of salt and vinegar.

Ammonia is an excellent cleanser for copper and brass,
but like all chemical solvents for tarnishes, should be
removed by washing as soon as the metal is clean.

Benzine and aromatic benzene are valuable constituents
of liquid polishes, since they act as general solvents.

Potassium cyanide is used in the trade, but as it is a
violent poison its use is unadvisable in the home.

Pastes. — These contain pulverized mineral material
made into paste form with soap, and in some cases small

210 HOUSEHOLD CHEMISTRY

amounts of oxalic acid, glycerol, or a hydrocarbon.
Their action is principally abrasive, and the mineral sub-
stances they contain are those found in the cleaning
powders described below.

Powders. — Efficient polishing powders are whiting,
clay, rouge, talc, quartz, emery, and silica.

Whiting is finely pulverized chalk. It costs about 10
cents per pound, and is useful for cleaning silver, nickel,
porcelain, and glass. A mixture of whiting with water
or alcohol is effective for window cleaning. One of the
scouring preparations on the market is essentially a mix-
ture of whiting and soap.

Clay is of varied character and comes under different
names — Tripoli, rottenstone, etc. These substances cost
about 40 cents per pound, and when in finely divided con-
dition are used for general metal cleaning. Rottenstone
is frequently mixed with kerosene for this purpose.

Rouge is preferred by jewelers for polishing gold and
silver, brass and copper. Jeweler's rouge is finely pul-
verized red oxide of iron, prepared by a special process,
and costs about 5 cents per ounce. When mixed with
water it will adhere to the surface on which it is rubbed.
Some of the best metal polishes on the market are com-
binations of rouge, oxalic acid, and a hydrocarbon.

Talc is pulverized magnesium silicate, and makes a
good polishing agent without danger of scratching.

Silica, quartz and emery come in different forms, as
knife brick, scouring soaps, etc., and are especially suited
to the polishing of steel and iron.

HOUSEHOLD CHEMISTRY 211

Polishing cloths are made usually by impregnating soft
durable fabrics with rouge, talc, rottenstone or whiting.
A polishing cloth may be made at home by dipping a pile
fabric or a piece of chamois into rouge mixed with water
or alcohol, and drying. Some of these cloths have no
mineral constituent, but polish by means of the fabric
itself.

TESTS FOR CLEANING AGENTS.

Oxalic Acid or Oxalates. — Make a water solution, filter, add
Ca(OH)2 to filtrate. White precipitate of calcium oxalate ap-
pears.

Benzine or Benzene. — Odor and inflammability.

Ammonia. — Odor and litmus test.

Potassium Cyanide. — Treat with fixed alkali, FeSO4, FeCU and
HC1 in order given. Prussian blue color.

Whiting. — Add CH3COOH. An effervescence indicates a car-
bonate. Make test for calcium.

Rouge. — Treat with boiling HC1 (cone.). If rouge is present,
it will dissolve. Make iron test with NH4SCN.

Clay. — Will remain insoluble when treated with water or acid.

Bleaches, Grease and Stain Removers. — Many pro-
prietary compounds are sold for these purposes. On an-
alysis, the bleaches are generally found to be calcium
hypochlorite, Javelle water, hydrogen and sodium per-
oxides, oxalic acid, or potassium permanganate, alone or
in combination. Some description of the use and effect
of these compounds is given in Chapter XIV. If the
kind of bleach required is known, it can be bought
directly, and at less expense than if purchased under its
proprietary name. For example, ink eradicators usually
consist of Javelle water or a solution of bleaching powder,

212 HOUSEHOLD CHEMISTRY

accompanied by an acid* — oxalic, muriatic, or citric — the
two being combined at the time of application.

The non-inflammable solvents for grease, familiar to
the public, have for the most part carbon tetrachloride
as their principal ingredient, with varying combinations
of benzine or gasoline, benzene, acetone, or chloroform.
They have a great advantage as to safety over the danger-
ous gasoline or benzine, often used carelessly in the
home. These grease solvents will remove fresh paint or
varnish stains, since they attack the fatty constituent in
the compound. Turpentine, benzene or amyl acetate also
soften and dissolve dried paint and varnish.

Bluings. — The character of the bluing used in the laun-
dry is of importance to the housewife. The three types
in common use — solid, liquid, and aniline blues — are
markedly different in properties.

Solid blues are now commercially prepared ultramarine
blues, the former type, indigo blue, being little used at
present. Ultramarine is found in nature in small quan-
tities as lapis lazuli ; as manufactured, it is a mixture of
sodium and aluminium silicates, and sodium sulphide. It
is characterized by insolubility in water, but the suspen-
sion of its fine particles in the bluing water gives a good
blue color. Unfortunately, unless care is used, larger
particles sometimes settle on the clothes, and produce
blue spots.

TEST.

Ultramarine blue is decolorized on addition of HC1 or
Sulphur is precipitated and H2S evolved.

HOUSEHOLD CHEMISTRY 213

Liquid Blues. — These are principally Prussian blue,
i. e., Fe4[Fe(Cn)6]3. Prussian blue decomposes in the
presence of an alkali, such as caustic soda, and gives a
brown residue of ferric hydroxide. This may happen if
soap is carried over into the bluing water. In that case
the ferric hydroxide becomes iron rust on the clothes,
when the hot iron is applied.

TEST.

Warm the sample of liquid bluing with NaOH. A brown
precipitate appears if the bluing has an iron base. Filter, dis-
solve residue in hot dilute HC1 and make test for ferric com-
pound, with NH4SCN.

Aniline Blues. — These are used less in the household
than in commercial laundries, but can be procured in
powder form at a laundry supply establishment. They
are cheaper than other forms of bluing, as I ounce of
the powder will make a strong solution in a gallon of
water. Acids are used in most laundries for the best
development of the color on the clothes. If an acid is
used, it should be acetic, which is volatile and harmless,
rather than oxalic, which is destructive to most fabrics.

TEST.

Aniline blues slowly lose color in the presence of caustic soda.

CHAPTER XVI.

VOLUMETRIC AND GRAVIMETRIC ANALYSIS.
Normal Solutions. — The basis of volumetric analysis is
the normal solution. A normal solution is one which
contains the hydrogen equivalent of the substance in
grams, in I liter of solution. For all monobasic acids
and alkalies the hydrogen equivalent corresponds with
the molecular weight of the compounds ; for dibasic sub-
stances it is one-half of the molecular weight. In sim-
ilar manner tri- and tetrabasic bodies have hydrogen
equivalents corresponding to one-third and one-quarter
of their molecular weight. To find the equivalent of a
salt, refer back to the acid from which the salt is made.
For example, Na2CO3 is the sodium salt of H2CO3, there-
fore it is dibasic, and its normal solution would contain
one-half its molecular weight, or 53, in grams per liter.

Equal volumes of normal solutions of different sub-
stances are of equal strength, and equal volumes of nor-
mal acid and alkali solutions neutralize each other.

Normal solutions may be made one-tenth or one-
hundredth of their full strength, either by taking the
corresponding fractions of their respective equivalents
or by diluting the full normal solutions proportionately;
they are known as deci- and centi-normal solutions re-
spectively.

To explain the preparation of the normal solutions of
acid and alkali, one example from each class will suffice,

HOUSEHOLD CHEMISTRY 215

and as hydrochloric acid and caustic soda have the most
extensive application, their preparation will be given.

Preparation of N/HC1. — The molecular weight of HC1
is 36.5, therefore 36.5 grams per liter are needed, but
as it is a volatile liquid and cannot be weighed with any
accuracy, it is usual to calculate the volume of the liquid
from its specific gravity, and to measure out the result
in cubic centimeters, allowing a little for loss. Using

W

the formula — = V, the calculation is simple and is

made as follows: divide the equivalent in grams (36.5)
by the specific gravity of the concentrated acid (1.2);
this gives 30.4-!- as a quotient and is the number of cubic
centimeters to be used if the acid were 100 per cent,
strength, but the strongest acid is only 40 per cent., hence
this quotient must be multiplied by 2.5 (30.4 X 2-5 =
76 cc.). It is safe to take 78-80 cc., adding it to 300 or
400 cc. of distilled water and when cool diluting to exactly
i liter.

The solution must now be standardized against a nor-
mal solution of an alkali which can be made exact.
Sodium carbonate, the equivalent of which is 53, can be
obtained of a high degree of purity and may be weighed
exactly. It is hardly necessary to make up a large quan-
tity, so that 5.3 grams of pure dry soda are usually
weighed accurately, dissolved in the least quantity of
water and the resulting solution diluted to exactly 100
cc. at or about 60° F. This constitutes the exact normal
soda, i cc. of which contains 5.3 milligrams of soda.

2l6 HOUSEHOLD CHEMISTRY

Measure 10 cc. of the soda very exactly with a pipette or
burette, run it into a small beaker containing about 100
cc. of distilled water and add 2 or 3 drops of methyl
orange solution. Fill a burette with the acid solution.
Note the level, and run it, drop by drop, with constant
stirring, into the soda. Stop when the last drop changes
the color from yellow to pink which remains even after
stirring for some moments. Read the burette and note
the number of cubic centimeters, and fractions used. Say
the quantity is 9.8 cc., indicating that this quantity con-
tains as much acid as should exist in 10 cc. ; consequently,
980 cc. of the liquid should be diluted to i liter. If the
total amount of acid is less, calculate what bulk it should
occupy and dilute accordingly. Continue the titration
until equal volumes of acid and alkali exactly neutralize
each other.

The acid keeps well, but should be preserved in tightly
stoppered glass bottles to prevent evaporation.

Preparation of N/NaOH. — The caustic soda is deliques-
cent and absorbs carbon dioxide, so must be weighed
rapidly and approximately, using rather more than the
40 grams required, say 50 grams. This is dissolved in
300 or 400 cc. of water, cooled and diluted to I liter.
Draw off 10 cc. of the normal acid in a pipette, allow it
to run into a small beaker containing about 100 cc. of
distilled water, and add a few drops of phenolphthalein.
Fill a clean, dry burette with the caustic soda. Note its
level and run it, drop by drop, with constant stirring, into
the acid solution until a faint but distinct pink tint

HOUSEHOLD CHEMISTRY 217

remains after stirring for some moments. Read off the
quantity used, say 9.5 cc., showing the solution to be too
strong and requiring dilution as in the case of the acid.
After performing this operation the acid and the alkali
should be correct and i cc. of one will exactly neutralize
an equal quantity of the other.

Use of Indicators. — A change in a solution from acidity
to alkalinity, or the reverse, can be shown by certain color
substances or indicators, sensitive to the slightest excess
of acid or alkali.1 The indicators in common use in
acidimetry and alkalimetry are phenolphthalein and
methyl orange. The work of an indicator may be illus-
trated by the action of phenolphthalein, a weak acid
which undergoes little dissociation in solution. In the
non-ionized state it is colorless. If, however, its acid
solution is neutralized by an alkali, a slight excess of the
alkali forms a salt of phenolphthalein which ionizes with
a deep red color. A strong base is necessary in order to
give a sharp reaction. Ammonia, for instance, is too
weak a base to ionize the weakly acid phenolphthalein in
dilute solution. Phenolphthalein is used most frequently
as an indicator for weak acids (excepting carbonic and
hydrosulphuric) titrated against normal sodium
hydroxide.

Methyl orange, on the other hand, is red in its molecu-
lar state, and changes to yellow on dissociation. It is
a moderately strong acid, and if added to a basic solu-
tion the salt formed is yellow, but the addition of a slight

1 For Theory of Indicators, see Ostwald : Foundations of
Analytical Chemistry, and Cairns: Quantitative Analysis.

2l8 HOUSEHOLD CHEMISTRY

excess of a strong acid is sufficient to produce the red
color of the non-ionized substance. Its reaction with
weak acids is not sharp, so its use is not advised in con-
nection with organic acids. Because of its strongly acid
nature methyl orange is useful in titrating against weak
bases. It must always be used in cold solution and in
small amounts.

Congo red and rosolic acid are usually employed in the
Kjeldahl determination of nitrogen. The former is blue
in acid solution, red in alkaline. It is dissolved in water
for use, and only small amounts should be taken. Rosolic
acid is yellow in the presence of acids; cherry red with
alkalies. It is dissolved in 50 per cent, alcohol for use.

To test unknown substances, first determine the com-
pound present by qualitative analysis, and then weigh or
measure some convenient quantity, dissolve or dilute with
distilled water, add the indicator and run in the acid or
the alkali until the neutral point is reached. Observe the
number of cubic centimeters used, multiply each by its
value in milligrams of the substance sought, and divide
the result by the quantity used ; multiplying this quotient
by 100 will yield per cent.

Value of i cc. of normal soda in each of the following :

Sodium carbonate 0.053

Acetic acid 0.060

Lactic acid o.ooo

Tartaric acid 0.075

Citric acid 0.064

Hydrochloric acid 0.0365

HOUSEHOLD CHEMISTRY 219

Nitric acid 0.063

Sulphuric acid 0.049

Potassium hydroxide 0.056

Ammonium hydroxide 0.035

Calcium hydroxide 0.037

For example, to neutralize 10 cc. of a solution of acetic
acid of unknown strength, 8 cc. of N/NaOH are re-
quired. The calculation would be :

i cc. N/NaOH = 0.06 gram acetic acid.

8 cc. N/NaOH were used,

8 X °-°6 gram = 0.48 gram acetic acid in 10 cc.

100 X (048 -T- 10) = 4.8 grams acetic acid in

100 cc.
. • . the strength of the acid is 4.8 per cent.

APPLICATIONS OF VOLUMETRIC ANALYSIS.

Analysis of Vinegars.— Take the specific gravity of the sample.
Decolorize a portion (50-100 cc.) by passing it through a bone-
black filter, rejecting the first funnel full. Take 10 cc. of the
product, dilute with a convenient bulk of water (about 50 cc.),
add I or 2 drops of phenolphthalein as indicator, and titrate
against N/NaOH. Calculate as acetic acid, using the specific
gravity of the vinegar to check the resulting per cent. Example :

Specific gravity of sample may be 1.014, . : . weight of 10 cc. =
10.14 grams.

Amount of acetic acid found in 10 grams may be 0.534 gram.

.- . 0.534 -f- 10.14 = 5.26, the per cent, of acetic acid in the
sample.

To distinguish the source of vinegar, evaporate 10 cc. to dry-
ness, and note the odor. Cider vinegar will give an odor suggest-
ing baked apples ; malt vinegar, a malt odor ; distilled vinegar, a
sharp acid odor. Ignite at a low temperature to light-colored
ash. In the case of genuine cider or wine vinegars the quantity
15

220 HOUSEHOLD CHEMISTRY

of ash is comparatively large and the reaction will be alkaline.
Synthetic vinegar will leave no appreciable residue.

Test for Free Mineral Acids.1 — Dilute 5 cc. of the vinegar
with 5 to 10 cc. of water to reduce the acidity to about 2 per
cent, of acetic acid, and add 4 or 5 drops of a solution of methyl
violet (i part of Methyl Violet 26, No. 56, of Bayer Farben-
fabrik, Elberfeld, in 10,000 parts of water). Mineral acids
change the blue violet color to a blue green or green.

Test for Phosphoric Acid. — Burn to ash in the presence of a
few drops of HNO3 and make the usual test for phosphoric acid.

Baking Soda. — Test for Purity? — Ordinary baking soda may
contain some Na2CO3. To determine the percentage of NaHCO3
in the sample, dissolve I gram of commercial NaHCO3 in 100 cc.
of distilled water, add 2 drops of methyl orange, and titrate
against N/io H2SO<. Since the freed carbonic acid is too weak
an acid to produce the red color with methyl orange, the latter
will give the end point of titration in this case only when the
N/io HjSCX has neutralized the total alkalinity (combined as
mono- and bicarbonate) of the soda.

Now dissolve another gram of the sample in 250 cc. of cold
water, add phenolphthalein, and titrate with N/io HaSCX. The
nose of the burette should dip into the solution, which should
be well stirred during the titration. No carbonic acid should
escape from the liquid during the operation. Under suitable
conditions of dilution and temperature the reaction is:

2Na2COs + H2SO4 m-» 2NaHCO3 -f Na2SO4.

Therefore, I cc. of half -normal sulphuric acid equals 0.106 gram
of NazCO3 present.

The difference between the amounts of N/io acid used in the
two titrations is the measure of the bicarbonate of soda in the
sample.

Cream of Tartar — Test for Purity. — Weigh i gram of cream
of tartar, add 100 cc. of distilled water, and 2 drops of phenol-

1 From Sherman's Organic Analysis.

2 Cairns : Quantitative Analysis.

HOUSEHOLD CHEMISTRY 221

phthalein. Run in N/NaOH until the pink color comes. (A
certain amount of the alkali is necessary to the complete solution
of the cream of tartar.) Now add N/io HC1 drop by drop until
the color just disappears, and subtract the amount used from
the alkali in terms of tenth-normal. The difference is the amount
of NaOH required to neutralize the cream of tartar. Calculate
the percentage of cream of tartar in the sample.

Household Ammonia. — Take the specific gravity of the sample,
and dilute 10 cc. with a convenient bulk of distilled water. Add
2 drops of methyl orange, and titrate against N/HC1. Calculate
percentage strength, using the specific gravity as a factor.

Analysis of Soap or Soap Powder.— In a 3-inch porcelain dish
place 1-2 teaspoonfuls of clean dry sand and a small glass stir-
ring rod; weigh the whole. Add 2-3 grams of the soap sample,
finely shaved, and enough 95 per cent, alcohol to cover the
material. Evaporate over a water bath, stirring meanwhile, until
the alcohol is evaporated. Dry the contents of the dish in an
air bath at 105° to constant weight. Estimate the loss in weight
as water.

Weigh another gram of the sample, finely shaved, and heat for
2-2^ hours in an air bath, at 105°. Treat the dried material on
a hot water bath with successive portions of hot neutral 95
per cent, alcohol, using about 50 cc. at a time and 400-500 cc. in
all. Decant each portion of the solution through a balanced
filter paper, finally washing the last portion through the filter
with additional alcohol. The combined filtrates contain the dis-
solved soap ; the residue on the filter paper is carbonates, chlor-
ides, borates, etc., and insoluble mineral matter. Proceed with
residue and filtrate as follows :

I. Residue. — Treat filter paper with boiling distilled water until
all trace of alkalinity or residue in the last 2 or 3 drops of the
filtrate has disappeared. Dry the paper in the air bath for about
an hour and calculate weight of insoluble material remaining on
it. Examine this under a magnifying lens for the presence of
glistening particles of pulverized quartz, etc. Make up the water
extract of the soluble material to bulk (e. g., 500 cc.), take 100 cc.

222 HOUSEHOLD CHEMISTRY

and determine total alkalinity by titrating against N/H3SO«.
Calculate as NaaCO8. In another 100 cc. calculate chlorides by
first exactly neutralizing with dilute HNO3, then titrating with
N/io AgNO8. Use potassium chromate as indicator. Calculate
that i drop of N/io AgNOs is equivalent to 0.000293 gram
sodium chloride. Concentrate a third portion to one-tenth bulk,
and make a qualitative test for borax as follows: Exactly neu-
tralize with dilute HC1, immerse a strip of freshly prepared
turmeric paper in the liquid, and dry at warm water heat. Make
a second test for borax on another portion, by boiling down
until all of the watery liquid has disappeared, cooling, adding a
mixture of equal parts of alcohol and glycerol, and applying a
flame. If the mixture burns with a yellow flame bordered with
green, borax is present.

Evaporate the balance of the solution to dryness, heating
finally to 110°, take up with a little water and a few drops of
HC1, and test for sulphates and silicates.

2. Filtrate. — Heat on a water bath until the odor of alcohol
has disappeared, keeping the solution up to full amount by addi-
tions of water. Cool, bring solution up to bulk, and determine
free alkali (NaOH) by titration against N/HaSO*. Then add
a known excess of the normal acid (e.g., 5 cc.), boil until clear,
add a weighed quantity (about 5 grams) of white wax, and melt.
Allow the mixture to stand undisturbed until the wax hardens,
remove the cake, press it between filter papers to remove all
moisture, and when dry weigh. The increase in weight is due
to fatty acids. Titrate the solution against N/NaOH. The
difference between the 5 cc. N/HaSCX added at the beginning
and the result now obtained gives the combined alkali. It should
amount to about one-seventh the weight of the fatty acids. Take
the sum of the weights of combined alkali and fatty acids as the
measure of the soap present in the sample.

Report in percentages the findings of water, carbonates,
chlorides, free and combined alkali, fatty acids, and insoluble
matter.

Test for Naphtha Soap.— Make a strong water solution of the

HOUSEHOLD CHEMISTRY 223

soap sample in a small flask, acidify slightly with diluted HaSCX,
and distill the mixture at as low a temperature as possible. If
any hydrocarbon is present it will pass over and condense with
the watery vapor. Note the odor.

For the detection of rosin or rosin oil in soap see page
208.

Analysis of a Cereal. — The process consists in the de-
termination of water, ash constituents, protein, fat, and
carbohydrate.

1. Water. — Dry 1-2 grams of the powdered cereal to constant
weight, at not over 105°. Calculate percentage of water, and use
figures obtained in correcting subsequent determinations of other
constituents.

2. Ash Constituents. — Ignite 5 grams of the material in a muffle
furnace at the lowest possible heat to char the material thor-
oughly. Cool, and make hot water extract of soluble alkaline
salts. A small portion of this liquid should be tested for chlor-
ides, sulphates, sodium and potassium.

Separate by filtration and evaporate the liquid. Dry the
charred residue and ignite to white or light-colored ash. Cool
and add the water extract and evaporate to dryness. Weigh ;
the result is total ash. Test the ash qualitatively for its con-
stituents, by the following method :

Dissolve in dilute HC1 with the aid of heat, the residue if
any should be small in amount and light in color. Any effer-
vescence observed before heating indicates COa, confirm with
lime water Ca(OH)». Make preliminary tests for iron and
ammonia on small separate portions of the liquid, the balance of
which is now divided into three unequal parts: A^2, Bj^, CJ4.
Treatment of A.

Add y2 a volume of Fe3Cl« and NH4C1 and enough NH4OH to
make the mixture decidedly alkaline, boil until the odor of
ammonia is faint and filter hot.

224

HOUSEHOLD CHEMISTRY

Precipitate:
Fe and Al as
phosphates
and hydro-
oxides.

Dissolve in the
least possible
amount of cold di-
lute HC1, add a
slight excess o f
clear NaOH, filter
and exactly neu-
tralize the clear
filtrate with dilute
HC1. A white floc-
c u 1 e n t ppt. of
A1(OH)3.

Filtrate:
Ca, Mg, K and Na as chlo-
rides. Make decidedly al-
kaline with NH4OH, add
(NH4)2C2O4 boil and filter.

Precipitate:
CaC2O4 sol-
uble in di-
lute HC1.

Filtrate:
Cool, add
more
NH4OH and
Na2HPO4
shake well.
Ppt.
NH4MgPO4.

Operation with B.

Divide into three equal portions.
Part I.

Add to this a few drops of silver nitrate ; a white curdy ppt. of
silver chloride, soluble in ammonium hydroxide.
Part II.

Add two drops of hydrochloric acid and a little barium chlor-
ide, a white crystalline ppt. of barium sulphate insoluble in HC1.
Part III.

Add a few drops (not more than 10) to I inch of ammonium
molybdate in a 6-inch tube. Heat the mixture in boiling water
about two minutes. A yellow crystalline ppt. ammonium phos-
phomolybdate.

C may be used in case of accident.

Protein. — Weigh 1-2 grams of the sample, place in a Kjeldahl
flask, add 20 cc. of concentrated sulphuric acid, 10-12 grams of
potassium sulphate, and 0.5 gram of copper sulphate. Partly
close the neck of the flask with a small funnel for purposes of
condensation, and heat under a hood, gently at first and then
strongly, until the mixture is colorless. It is well to continue
heating for 15-20 minutes after this stage is reached. The nitro-
genous matter in the cereal has been converted into ammonium
sulphate by the acid of the sulphuric acid. The process now
consists in liberating ammonia from this by the addition of caus-

HOUSEHOLD CHEMISTRY 225

tic soda, distilling the free ammonia into a known amount of
sulphuric acid, and calculating the amount of nitrogen present.

Proceed by cooling the material in the Kjeldahl flask, adding
about 250 cc. of distilled water, and after the solid matter has
dissolved, 4 or 5 drops of rosolic acid. Put 10 cc. of N/io
H2SO4 and a few drops of Congo red in an Erlenmeyer receiv-
ing flask, and arrange to connect distilling and receiving flasks
with a water condenser. The delivery tube of the condenser
should reach below the acid in the receiving flask. Place small
pieces of zinc and paraffin in the Kjeldahl flask to prevent bump-
ing, add 80 cc. or more of caustic soda (about 38° Be.) and
connect up at once. Distill over a low flame at first, later in-
crease the heat, until about half the contents of the flask have
passed over. If the color in the receiving flask becomes red,
showing an excess of ammonia, quickly add a measured addi-
tional amount of the N/io H2SO4. Titrate the excess of acid in
the flask against N/io NaOH and calculate that i cc. of N/io
H2SO* is the equivalent of 0.0014 gram nitrogen. As the aver-
age percentage of nitrogen in protein material is approximately
16, the grams of nitrogen found multiplied by the factor 6.25
will give the amount of protein in the sample.1

Fat. — Weigh 1-2 grams of the air-dried, pulverized material,
place in an extraction thimble, and introduce into a Soxhlet or
other approved form of extraction apparatus. Extract with a
pure form of ether into a tared flask. The duration of the
extraction depends on the character of the material, but 16 to
24 hours are usually allowed.

Remove the flask, evaporate the ether, weigh, and calculate
amount of extract.

Carbohydrate. — Determine carbohydrate by difference. If the
cereal has a notable amount of soluble carbohydrate, make a
water extract, invert and estimate reducing sugar, and determine
the insoluble carbohydrate by difference. Use the following
method :

1For modifications of the Kjeldahl method, see Sherman:
Organic Analysis.

226 HOUSEHOLD CHEMISTRY

Estimation of Reducing Sugars.— Mix 15 cc. of Fehling's solu-
tion A with the same amount of Solution B in an Erlenmeyer
flask of about 250-300 cc. capacity, add about 50 cc. of freshly
boiled distilled water, and heat in boiling water for 5 minutes.
Measure with a pipette 25 cc. of the sugar solution, which should
be of such a strength as not to contain more than 0.5 gram of
reducing sugar. Add this to the Fehling's mixture and place
the flask in boiling water for 15 minutes. Remove, filter at once
with the aid of moderate suction through a Gooch crucible pre-
pared with asbestos.1 If the filtrate is not distinctly blue, show-
ing that an excess of Fehling's has been used, the operation
must be repeated with a more dilute solution of the reducing
sugar. Wash the precipitate of cuprous oxide with boiling dis-
tilled water until the filtrate is no longer alkaline. The cuprous
oxide can now be (i) washed with alcohol and then with ether,
dried in an air bath at 100° for 20 minutes, weighed as cuprous
oxide, and calculated to its cupric oxide equivalent. The cor-
responding weight of reducing sugar may then be determined
by referring to Defren's table (see Sherman: Organic Analysis).

Or (2) the cuprous oxide may be ignited and weighed as

*To prepare the Gooch crucible for gravimetric determina-
tion of cuprous oxide, proceed as follows: Boil a good quality
of asbestos with nitric acid (specific gravity 1.05 to i.io), wash
with water, boil with 25 per cent, sodium hydroxide, wash, and
repeat the treatment. Finally stir the washed asbestos with
water, pour some into a Gooch crucible, and draw it into place
with moderate suction. When a tight felt about I centimeter
thick has been laid down, ignite a constant weight and record
weight of crucible and asbestos. Test by running through it a
"blank" of hot alkaline Fehling's solution and washing with
water as in a regular determination. The loss in weight should
not exceed ^ milligram. If it does, the filter is again treated
with acid and alkali until it ceases to lose in weight. The cruci-
ble may be used for successive determinations by dissolving the
precipitate each time with nitric acid, washing, igniting to con-
stant weight.

HOUSEHOLD CHEMISTRY 227

cupric oxide and the corresponding amount of reducing sugar
found as before. A third method consists in determining the
copper by electrolysis (see Allihn's method and table for the
determination of dextrose).

CHAPTER XVII.

REAGENTS.

Commercial
forms

laboratory strength

Sp. gr.

Per
cent.

Concentrated

Sp. gr.

Dilute

Sp. gr.

Vols.
H2O

Vols.
acid

Acids
HC1 - .

1.2

1.4
1.84
1.06

0.9

40
70

94
50

28

full strength
Vols. Vols.
H2O acid
I I
full strength
full strengfh

full strength
20 per cent.
20 per cent.

dry

dry

dry
dry

1.2

1.2

1.84
1. 06

"•3

1.23

I
3

7

10
Vols.
H2O
I

10 pei
lopei

lopei
10 pei
satui
satui
10 per
satui

5 pei
satui
satui
satui
20 per
5 per
10 per
10 per

I

I
I

I

Vols.
alk
I
cent,
cent.

cent.
• cent,
•ated
-ated
cent,
•ated
cent,
•ated
•ated
•ated
cent,
cent,
cent,
cent.

I.I

I.I
I.I
1.007

0-945
1.14
i.i

i.i

1.2

HN03
H SO • •

CH3COOH .

Alkalies

NH4OH ....
NaOH

KOH . . .

Salts
Na CO .

BaCl ....

(NH4)2C204.
Na2HPO4 • . .
NH Cl

(NH4),S04 .
NH4SCN . . .
NaCl •

MgS04

HcrCl

AgN03
Co(NO,)s...

K4Fe(CN)6 .

Special Reagents.

Ammonium Molybdate, (NH4)2MoO4.
Dissolve 100 grams MoO3 in 200 cc. strong NH4OH

HOUSEHOLD CHEMISTRY 22Q

and 200 cc. H2O; slowly pour resulting solution in 1,500
cc. HNO3, specific gravity 1.2.

Magnesia Mixture.

i gram MgSO4 or MgCl2, I gram NH4C1, 4 cc. am-
monia, 8 cc. water.

Milton's Reagent. — 100 grams mercury dissolved in
71.5-72 cc. HNO3 specific gravity 1.4 in the cold, when
action ceases add twice the volume of cold water.

Fehling's Reagent. — Solution A — 34.64 grams CuSO4,
5H2O in 400 cc. of cold water, when dissolved make up
to 500 cc.

Solution B — 50 grams NaOH + 180 grams NaKC4
H4O6 in 300 cc. of water, when dissolved and cooled
make up to 500 cc.

For use mix equal volumes of A and B and add two
volumes of water.

Barfoed's Reagent. — 4.0 grams copper acetate, 100 cc.
water, 2 cc. acetic acid.

Nylander's Reagent. — Two grams bismuth subnitrate,
(BiONO3), and 4 grams of Rochelle salt, (NaKC4H4O6),
in loo cc. of 8 per cent. NaOH, specific gravity 1.08.

Nessler's Reagent. — 35 grams of KI and 13 grams of
HgCl2 in 800 cc. H2O. Heat below boiling until dis-
solved, add immediately a cold saturated solution of
HgCl2, until the red precipitate fails to dissolve after
stirring. Cool and add 160 grams KOH dissolved in as
little water as possible, and make up to I liter. After
standing 24 hours pour off the clear liquid and reserve
for use. If necessary, add a little more (3-5 cc.) HgCl2

230 HOUSEHOLD CHEMISTRY

to increase the sensitiveness. When properly prepared,
the solution has a pale yellow color.

Griefs Reagent for Nitrites. — Dissolve I gram of sul-
phanilic acid in 300 cc. of acetic acid, specific gravity
1.04 (30 per cent.).

Boil 0.2 gram of o-naphthylamine in 400 cc. of dis-
tilled water, filter through a plug of washed absorbent
cotton and add 360 cc. of acetic acid (30 per cent.).

To dilute 50 per cent, acid to 30 per cent., take ^ of
loo or 60 cc. of acid and dilute to 100 cc.

Basic Acetate of (Sugar of) Lead Solution. — Boil 232
grams of lead acetate and 132 grams of litharge (PbO)
in 750 cc. of distilled water for half an hour, cool and
dilute to i liter. Allow liquid to stand until clear and
decant. Specific gravity of solution should be about
1.267.

Alumina Cream for Clarifying Syrups, Etc. — Make a
saturated solution of powdered alum [KA1(SO4)2] in
water at 6o°-7o° F. ; set aside a small portion (o.i of the
whole) and add to the balance ammonium hydroxide,
carefully with stirring, until the mixture is just alkaline
to litmus paper. Drop in the reserve liquid until the mass
is faintly acid. This mixture consists of aluminium hy-
droxide suspended in ammonium sulphate solution.

Meta Phosphoric Acid. — Dissolve glacial phosphoric
acid (HPO3) or phosphoric anhydride, P2O5, in ice and
water. As the solution rapidly changes to H3PO4 make
it fresh for each day's work.

Alcohol. — 95 per cent, is always acid; neutralize with
dilute alkali before using. Alcohol may readily be recov-

HOUSEHOLD CHEMISTRY 23!

ered from solutions and wash liquids by distilling over
hot water at 78°-8o°.

Ammonium Sulphide. — Mix equal volumes of distilled
water and strong ammonia (specific gravity 0.9) ; divide
the resulting solution in equal parts. Pass a current of
H2S through one-half the solution until saturated and
then add the balance of the dilute ammonia.

Alkaline Pyrogallol. — Dissolve 20 grams of the best
pyrogallol in 100 cc. of cooled freshly boiled distilled
water, add 0.5 cc. of concentrated H2SO4. This solution
keeps well.

For use take enough of the above and make strongly
alkaline with 10 per cent. NaOH. Avoid contact with
air and use immediately.

Alkaline Potassium Permanganate. — 8 grams of crys-
tallized potassium permanganate with 200 grams of
caustic potash or a corresponding amount of caustic soda,
in i liter of water.

Acidified Potassium Permanganate. — 0.395 gram po-
tassium permanganate in I liter of water. Add 10 cc. of
H2SO4 before using.

Alcoholic Potash. — 56 grams KOH in i liter 95 per
cent, alcohol.

Molisckfs Reagent. — Make a 15-20 per cent, alcoholic
solution of alpha-naphthol. Use with H2SO4 as directed.

Schweitzer's Reagent.* — Dissolve 5 grams of copper
sulphate in 100 cc. of boiling water, add caustic soda solu-
tion until the cupric hydroxide is completely precipitated,
wash the precipitate well and dissolve in the least quan-

232 HOUSEHOLD CHEMISTRY

tity of 20 per cent. NH4OH (3 volumes ammonia specific
gravity 0.9 -|- I volume H2O = 20 per cent.).

Viscogen. — Dissolve two and one-half parts of granu-
lated sugar in five parts of water. Slake one part of
lime in three parts of water, strain and add to the sugar
liquid. Shake frequently for two or three hours and
allow to stand; finally pour off the clear liquid (viscogen)
and keep in a well stoppered bottle. Access to air turns
the liquid dark but does not impair its usefulness.

APPENDIX.

Useful Tables and Equivalents.

Per cent.

Sp. Gr.

Degrees B6

HCf)

a/^ -5 r

rvi*7

760

• «-»<•»/

9-584

.066

9

93.5 (cone.)

.835

66

HC1 .

1.124

.006

j

10.17

•05

7

20.00

.1027

13-5

40.55

•2033

24-5

NaOH

1.2

.OI4.

2

10.06

!n6

15

11.84

.134

17

20.59

.231

27

24.81

.274

31

32.47

•357

38

I gram =

28.35 grams =

453-6 grams =

I kilogram =

i teaspoon =

i tablespoon =

1 cup =

2 cups =
I pint water =

I gal. (U. S.) water =

I gal. (Eng.) water =

I liter water =

I liter =

i inch =

i foot -

I cu. ft. water =

I cu. ft. water -

i cu. ft. ice =

[15.432 grams
0.0353 oz.
O.OO22 Ib.
I OZ.

i Ib.

2.2 Ibs.

5 cc.

15 cc.

16 tablespoons
i pint

I Ib. approx.

8.3 Ibs. or 231 cu. in.
10.0 Ibs. or 277-J- cu. in.
i kg.
1.057 Qt. (U. S.)

2.54 cm. or 0.0254 meter
30.48 cm. or 0.3048 meter
62.35 Ibs.

7.5+ U. S. gals.
56+ Ibs.

234

HOUSEHOLD CHEMISTRY

Method of changing from a stronger to a weaker solu-
tion, e. g., from acetic acid of 50 per cent, strength to 20
per cent. :

20 per cent. : 50 per cent. : : 100 cc. : x cc.
x — 250 cc.

Therefore make up 100 cc. of the 50 per cent, acetic
acid to 250 cc.

Interchange of Centigrade and Fahrenheit degrees :

F = — C -f 32 C = — (F — 32).

5 9

Comparison of Fahrenheit and Centigrade degrees :

Fahr.

Cent.

Fahr.

Cent.

O

32

—17.78
o.oo

$

35-°°
36.67

40

4-44

100

37.78

41

5-00

104

40.00

50

IO.OO

"3

45 .00

59

15.00

122

50.00

&

18.33

20 .00

140
145

60.00
62.78

72

22.22

158

70.00

£

25.00
26.67

3

75.00
80.00

212

IOO.OO

To convert degrees Baume to specific gravity apply the
formulas :

For liquids heavier than water —

144

— -^£o = specific gravity.
144 — ue

For liquids lighter than water —
144

134 -I-

= sPecific

HOUSEHOLD CHEMISTRY 235

lonization Values.

The following table shows approximately the percent-
age of the substance which is dissociated into its ions in
o.i normal solution at 25°. In the case of the dibasic
acids the value opposite the formula of the acid shows the
percentage of the first hydrogen that is dissociated, and
that opposite the acid ion (HA-) shows the percentage
of it dissociated (into H -j- and A= for the case that
these two ions are present in equal quantities).

Per cent.

Salts of type B+A- (e.g. KNO3) 84

Salts of type B2+A= or B++A2- (e.g. K2SO4 or BaCl2) . . 73
Salts of type B3+A^ or B+++A3- (e.g. K3Fe(Cn)6 or

A1C13) 65

Salts of type B++A= (*.£-. MgSO4) 40

KOH, NaOH 90

Ba(OH)a 80

NH4OH i

HC1, HNO3, H,SO4 90

H3PO4, H2SO3, (COOH)a 20-45

CHaCOOH 1-2

H,S, H,C03 0.1-0.2

HOH . . 0.0000002

16

List of Apparatus for Students in Household Chemistry,

Three rings (iron).
Filter ring.
Clamps.
Triangular file.
Round file.
Triangles.
Wire gauze.
Steel forceps.
Wing-top.
Horn spatula.
Tube brushes — three (as-
sorted sizes).
Filter paper.
Test tube holder.
Scissors.
Knife.
Thermometer. Centigrade

0°-I20°.

Glass rod with platinum

wire.

Flat glasses, 4-inch.
Blue glass.
Watch crystals — four.

Microscope slides with cov-

er glasses — four.
Test tubes — i doz. 6-inch.
Test tubes — i doz. 4-inch.
Hard-glass test tubes ( i in.

X 6 in.) — two.
Graduates, 10 cc., 25 cc.
Porcelain dishes — two

(3^-inch).
Beakers (Jaikel 1-4).
Tripod.

Test tube rack.
Agate boilers with cover,

4 funnels — 2-inch and 3-

inch.

Flasks — one 4 oz. high.
Flask s — two 4-oz. low

(wide mouth).
Flask — one i6-oz. round

bottom.

Wash-bottle— 16 oz.
Wide mouth bottle, 8-oz.
Water-bath, 5-in.

INDEX.

Acetic acid fermentation, 185.
Acetylene, preparation of, 83,

85,86.

Acrolein, 130, 135.
Air, aqueous vapor in, 10.

carbon dioxide in, 7, 10.

composition of, 7-14.

density of, 12.

diffusion of gases in, 13.

dust in, 12.

experiments on, 14-16.

heat capacity of, 14.

humidity of, u.

liquid, 14.

nitrogen in, 9, 10.

oxygen in, 8, 9.

ozone in, 9.
Albumins, 141, 147-150.

tests for, 147-150.
Alcohol, denatured, 75.

ethyl, experiments with, 77,
78.

ethyl, preparation of, 76, 77.
Alcohols, as burning fluids, 75-

78.
Alum, in water purification, 37.

test for, 33, 174.
Aluminium, alloys of, 54.

experiments on, 54.

in utensils, 54.

preparation of, 52, 53.

properties of, 53.

Ammonia, albuminoid, 33-35.
free, 33-35.

Analysis, volumetric and gravi-
metric, 214-227.

Antiseptics, 195-197.

Atmosphere and ventilation, 7-
22.

Aqueous vapor in air, 10.

B

Babcock test, 162.

Baking powder, home-made,

171.
Baking powders, 169-174.

classification of, 170.

comparative table of, 172.

experiments on, 173, 174.

reactions in using, 170, 171.
Baume hydrometer, 25, 234.
Beef extracts, 157, 158.

food value of, 157.

tests on, 157.
Biuret test, 148.
Blau gas, 84.
Bleaches, 196, 197, 211.
Bluings, 212, 213.
Bones, 153.

Butter, specific tests for, 138.
Butyric acid fermentation, 138,
139.

Calcium, test for, 33.

INDEX

Carbohydrates, 87-121.

celluloses, 115-120.

classification and occurrence,
88-90.

description of, 87.

dextrin, 113, 114.

fructose, 99, 100.

galactose, 100.

general reactions of, 93, 94.

glucose, 94-98.

glycogen, 114, 115.

hydrolysis of, 91, 92.

in fruits, 122, 124, 126, 127.

lactose, 106, 107.

maltose, 103-105.

optical activity of, 92, 93.

photosynthesis of, 90, 91.

practical work on, 120, 121.

solubilities of, 93.

starch, 107-113.

sucrose, 100-103.

ultimate composition of, 93,

94-
Carbon dioxide determination,

174-

in air, 7, 10.
Carbonates, test for, 33.
Celluloses, 115-120.

experiments on, 117-120.

occurrence of, 115, 116.

properties of, 116, 117.
Cereals, 120, 121.

analysis of, 223-225.

practical work on, 120, 121.
Cheese, 167, 168.

Chlorides, in water, 36.

test for, 33.

Chocolate and cocoa, 180, 181.
Cleaning agents, 200-213.

classification of, 200.

tests for, 208, 211.
Clotting, 145.
Coagulation, 144.
Coal, fuel value of, 68.
Coal gas, 80, 81.
Coffee, 176-180.

experiments on, 177.

notes on making, 177-180.
Copper, alloys of, 51.

experiments on, 52.

manufacture of, 50, 51.

properties of, 51.
Cotton, tests for, 119.
Cottonseed oil, tests for, 137,

138.
Curdling, 145.

Density of air, 12.
Dextrin, 113, 114.

experiments on, 114.

preparation of, 113.

properties of, 113.
Diffusion of gases, in atmos-
phere, 13.
Disinfectants, 194-199.

tests for, 198, 199.
Disinfection, 194-199.

chemical methods of, 195-197.

physical methods of, 194, 195.
Drying oils, 131, 137.

INDEX

239

Dust, in air, 12.

E
Eggs, 147-150, 153-155, 192.

tests on, 153-155.
Enamel ware, 62.
Ethylene, preparation of, 85.

Fats, 128-139.

acids in, 129.

chemical nature of, 128.

experiments on, 134-138.

hydrolysis of, 132.

properties of, 129-134.
"Fatty acids, 129.
Ferments and preservatives,
182-193.

Ferments, 182-186.

acetic, 185.

butyric, 185, 1 86.

experiments on, 186, 187.

lactic, 183-185.

yeast, 182, 183.
Filters, household, 38.
Formalin, in milk, 166.
Flue dust, corrosive action of,

69.
Fructose, 99, 100.

experiments on, 99, 100.
Fruits and fruit juices, 122-127.
Fruits, analysis of, 124-127.

composition of, 122-124.

in jelly making, 127.

Fuels, 66-86.
classification of, 66.
gaseous, 78-86.
liquid, 69-78.
solid, 67-69.

Galactose, 100.
Gas, 79-86.

acetylene, 83, 85, 86.

analyses of, 81.

Blau, 84.

coal, 80, 81.

combustion of, 82, 83.

naphtha or gasoline, 83, 84.

natural, 78, 79.

Pintsch, 84, 85.

water, 79, 80.
Gas meters, 82.
Gases, fuel and illuminating,

78-86.

Gasoline, tests on, 73, 74.
Gelatin, 151-153.
Glass, 61-63.
Gliadin, 151.
Globulins, 142.

separation of, 149.

special tests for, 148, 149.
Glucose, 94-98.

experiments on, 96-98.

preparation of, 94.

properties of, 95, 96.

structure, 94.
Glucosides, 98.
Glutelins, 151.
Gluten, 151.

240

INDEX

Glycerides, 128.
Glycogen, 114, 115.

H

Hardness of water, 38-42.
Humidity in atmosphere, n.
Hydrogenation, 131.
Hydrolysis, definition of, 26.

of carbohydrates, 91, 92.

of fats, 132.

of proteins, 145, 146'

A

Ice cream, analysis of, 166.
Indicators, use of, 217, 218.
Iodine value, of fats, 137.
lonization values, 235.

Iron, 43-50-
experiments with, 47.
in utensils, 44.
galvanized, 46, 50.
manufacture of, 43. 45-
oxides of, 43.
properties of, 44, 47-
tests for, 33.

Jelly making, 127.

K
Kerosene, 74, 75-

L

Lactic acid fermentation, 183-

185.

Lactose, 106, 107.
Latent heat of water, 23, 24.

Lead, 59, 60.
Lignocellulose, 119.
Linen, tests for, 119.
Liquid air, 14.
Liquid fuels, 69-78.

M

Magnesium, test for, 33.
Maltose, 103-105.
Metal polishes, 209-211.
Metals, 43-60.
Metaprotein, preparation of,

149, 150.

Methane, preparation of, 85.
Milk, 158-166.

analysis of, 158, 163, 164.

average composition of, 158.

condensed or evaporated, 166.

detailed composition of, 156-
160.

effect on, of heating, 160.

effect on, of rennin, 161, 164,
165.

fermentation of, 161.

sour, 160.

souring of, 160, 165.

tests on, 161-166.

Muscle, 155-157.
constituents of, 155, 156.
experiments on, 156, 157. •

N

Naphtha gas, 83, 84.
Natural gas, 78, 79.
Nickel, 47, 48.

INDEX

241

Nitrites and nitrates, in water,

35, 36.
Nitrogen in air, 9, 10.

Optical activity, 92, 93-
Organic chemistry, outline of,

2-6.
Oxygen consuming power, of

water, 36.

Oxygen in air, 8, 9.
Ozone in air, 9.

Paper, tests on, 119, 120.
Pectin and pectose, 122, 123,

127.
Petroleum, 69-72.

chemical nature of, 71, 72.

combustion of, 72, 73.

cracking of, 70.

development of industry, 69,
70.

distillates from, 71.

experiments on products of,

73-75.

Photosynthesis, 90, 91.
Phosphates, test for, 32.
Pintsch gas, 84, 85.
Polishes, metal, 209-211.
Pottery and porcelain, 64, 65.
Preparation of N/HC1, 215,
217.

of N/NaOH, 216, 217.

Preservation of foods, 187-190.

chemical methods of, 188, 189.

physical methods of, 187, 188.
Preservatives, experiments on,

189, 190.
Proteins, 140-168.

albumin, 147,150.

alcohol solubles, 151.

beef extracts, 157, 158.

bones, 153.

cheese, 167, 168.

classification of, 140, 141.

description of, 140.

eggs, 147-150, 153-155.

gelatin, 151-153.

globulin, 150, 151.

glutelins, 151.

hydrolysis of, 145, 146.

in fruits, 123, 126.

milk, 158-166.

muscle, 155-157.

occurrence and solubilities
of, 141-144.

properties of, 144-146.

ultimate composition of, 146,

147.

Proteoses and peptones, prepa-
ration of, 150.

Purity of foods, tests for, 190-
193.

Rancidity, 133.

Reagents, preparation of, 228-

232.
table of, 228.

242

INDEX

Reducing sugars, estimation of,

226, 227.
Rennin, 145, 161, 164, 165.

S

Saccharimeter, 101, 102.
Saccharin, 192.
Salt-rising bread, 184.
Scouring powders, 208-210.
Silver cleaning process, 57.
Silver, 54-57.

alloys of, 56.

in utensils, 57.

preparation of, 55, 56.

properties of, 56.
Soap, analysis of, 205, 208.

average composition of, 205.

chemistry of making, 133,
205, 206.

cleansing action of, 201.

cold, 205-207.

manufacture of, 201-204.

recipes for, 206, 207.

rosin in, 205.

tests on, 208.

Solutions, normal, 214-218.
Starch, 107-113.

experiments on, 110-113.

properties of, 107-110.
Steel, 45, 46.
Sucrose, 100-103.

experiments on, 102, 103.

properties of, 100, 101.
Sulphates, test for, 33.

Tea, 175, 176.
Tin, 57-58.

alloys of, 58.

experiments on, 58.

in utensils, 58.

manufacture of, 57, 58.

properties of, 57.

U

Unknown substances, method
of testing, 218, 219.

Ventilation, 16-22.

methods of, 20-22.

relation of carbon dioxide to,
18-20.

relation of heat and humidity

to, 16-18.

Viscogen, 103, 232.
Vitamines, 138.
Vitellin, 154.
Volumetric analysis, 214-227.

applications of, 219-223.

W

Water, 23-42.
boiling and freezing points

of, 24, 28.

chemical properties of, 25-27.
compressibility and expansion

of, 25.

conductivity of, 24, 27.
density of, 25.
hard and soft, 38-42.
latent heat of, 23, 24.

INDEX

243

Water, mineral matter in, 30.
of hydration, 26, 29.
of hydrolysis, 26, 27, 29.
of solution, 26.
oxygen consuming power of,

36.

physical properties of, 23-25.
purification of, 37, 38.
qualitative examination of,

30-36.

specific heat of, 24.
total solids in, 32, 33.

Waters, natural, classification

of, 29, 30.
Wood, 67, 68.

Yeast fermentation, 97,
183.

Zinc, 48-50.

182,

Food Industries

An Elementary Text-Book on the Production and

Manufacture of Staple Foods

BY

HERMANN T. VULTE, Ph.D., F.C.S.

Profewor Household Arts, Teacher* College, Columbia University

AND
SADIE B. VANDERB1LT, B. S.

Instructor Household Arts, Teachers College, Columbia University
New York, N. Y.

CONTENTS: Introduction. Chapter I.— Foodstuffs.
Chapter II.— Water. Chapter III.— Cereals. Chapter
IV.— The King of Cereals. Old Milling Processes.
Chapter V.— Modern Milling. Chapter VI.— Breakfast
Foods. Chapter VII.— Utilization of Flour. Bread-
making. Chapter VIII. — Leavening Agents. Chapter
IX.— Starch and Allied Industries. Chapter X.— The
Sugar Industry. Chapter XI. — Fruits, Vegetables and
Nuts. Chapter XII.— Fats. Chapter XIII.— Animal
Foods. Chapter XIV.— The Packing House. Chapter
XV.— Milk. Chapter XVI.— Milk Products. Chapter
XVII.-nPreservation of Foods. Chapter XVIII.— The
Canning Industry. Chapter XIX.— Tea, Coffee and
Cocoa. Chapter XX. — Non-alcoholic Beverages. Chap-
ter XXI. — Spices and Condiments, Bibliography.
Index.

8vo. Pages X + 325. 81 Illustrations.
Price, $3.00, Postpaid.

A New Type of College Education j|

OFFERED BY THE

SCHOOL OF PRACTICAL ARTS
TEACHERS COLLEGE,
Columbia University

The School of Practical Arts offers curricula leading
to the degree of Bachelor of Science, combining cultural
and vocational training. The usual college subjects such
as English, History, Modern Languages and Science are
supplemented by professional courses of collegiate grade
in one or more of the following fields : Fine Arts, House
Design and Decoration, Costume Design and Illustration,
Foods and Cookery, Textiles and Clothing, Household
Administration, Industrial Drawing, Metal Working,
Wood Working, Music, Physical Education and Nurses
Education. Preparation for teaching any of above
subjects may be included.

Graduate courses leading to higher degrees with
opportunity for specializing in the above fields are also
offered.

For full information address the Secretary of Teachers
College.

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MAR 30 1936
MAR 21 1939

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