49
^LABORATORY STUDY °I
HOUSEHOLD CHEMISTRY
JONES
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WM
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Book t s/ jL
Copyright N°
COFXRIGiST DEPOSFT.
A LABORATORY STUDY
OF
HOUSEHOLD CHEMISTRY
BY
MARY ETHEL JONES
FORMER TEACHER OF CHEMISTRY IN THE
LOS ANGELES HIGH SCHOOL
>XK<
ALLYN and BACON
BOSTON NEW YORK CHICAGO
ATLANTA SAN FRANCISCO
-ft***
51
COP /RIGHT, 192i,
BY MARY E. JONES
SEP 24 '2
NorinooB Press
J. S. Cushing Co. —Berwick & Smith Co
Norwood, Mass., U.S.A.
©C1.A627093
PREFACE
These experiments in Household Chemistry are arranged
to meet the demand for work in chemistry for girls. They form
a practical course in the chemistry of the household and of
common things, and are helpful both to pupils who do not go to
college and to those who do.
Above all, the course u practical. While the fundamental
principles of chemistry are as thoroughly emphasized in the first
half year of this course as they are in any course in general chem-
istry, the experiments that illustrate them are made as prac-
tical as possible.
The last half of the course is largely organic chemistry made as
simple as possible and used so far as possible in the study of fuels
and illuminants, food principles, food substitutes, textiles, soaps,
laundering, bleaching, blueing, dyeing, and leavening agents.
All of the experiments and the wording of the directions have
been tried for five years by different teachers with classes of
girls. Additions and changes have been made each term until
the manual satisfies all the requirements of the course.
Many teachers have assisted in the preparation of this work.
The author wishes particularly to express her indebtedness to
Miss J. Maud Blanchard, her first teacher in chemistry, to Miss
May Kimble and Mr. J. H. Hanna, both of the Los Angeles
High School, and to Mr. C. W. Sandifur, of the Hollywood High
School.
Mary Ethel Jones
Los Angeles, California
April, 1921
iii
CONTENTS
Part I. First Term's Work
I Preliminary Experiments
Experiment 1. The Bunsen Burner ....
Experiment 2. The Units of Length, Volume, and
Weight Used in Chemistry .....
Experiment 3. How to Make Simple Apparatus from
Glass Tubing
Experiment 4. Physical and Chemical Changes .
Experiment 5. Elements, Compounds, Mixtures .
II Oxygen and Hydrogen
PAGE
2
Experiment 6.
Experiment 7.
Experiment 8.
Burns
Experiment 9.
drogen
Experiment 10.
drogen
Ways of Freeing and Collecting Oxygen
Preparation and Properties of Oxygen
What Takes Place When a Substance
Preparation and Properties of Hy-
Two Other Methods of Preparing Hy-
III
IV
Water
Experiment 11.
Experiment 12.
Experiment 13.
Experiment 14.
Water
Experiment 15.
Experiment 16.
Nitrogen and the Air
Experiment 17.
gen .
Experiment 18.
Experiment 19.
The Synthesis of Water
How to Test Hydrogen and Water
The Solvent Power of Water
Boiling Point and Freezing Point of
How to Purify Water
Properties of Hydrogen Peroxide
Preparation and Properties of Nitro-
The Composition of the Air
Ammonia, NH3 .....
12
14
17
19
22
24
25
28
30
32
34
35
37
40
Vi CONTENTS
V Acids, Bases, and Salts page
Experiment 20. General Properties of Acids, Bases,
and Salts 41
Experiment 21. Methods of Forming Acids, Hy-
droxides, and Salts 45
Experiment 22. Solutions That Conduct the Electric
Current 49
VI The Halogens and Hydrochloric Acid
Experiment 23. Chlorine, Bromine, and Iodine . . 52
Experiment 24. Preparation and Properties of Hydro-
chloric Acid, HC1 54
VII Sulfur and Compounds of Sulfur
Experiment 25. Sulfur and Compounds of Sulfur . 55
Experiment 26. Sulfuric Acid and Hydrogen Sulfide . 57
VIII Carbon. Carbon Dioxide. Flames
Experiment 27. Carbon 59
Experiment 28. Carbon Dioxide, C02 .... 60
Experiment 29. Carbonic Acid and Carbonates . . 62
Experiment 30. Flames 63
Part II. Second Term's Work
IX Common Organic Compounds
Experiment 31. Tests for Organic Compounds . . 67
Experiment 32. Hydrocarbons 69
Experiment 33. Some Common Alcohols ... 73
Experiment 34. Properties and Uses of Some Common
Organic Acids 76
Experiment 35. Fuels and Illuminants ... 80
X Chemistry of Foods
Experiment 36. Water in Foods 83
Experiment 37. Inorganic Salts in Foods (Mineral
Matter or Ash) 84
Experiment 38. Starch and Dextrin .... 86
Experiment 39. Cellulose 88
Experiment 40. Gums and Pectin .... 90
Experiment 41. Sugars 93
Experiment 42. Fats and Oils 96
CONTENTS
Vll
Experiment 43. The Albumens and Casein
Experiment 44. The Globulins and Albuminoids
XI Digestion of Food
Experiment 45.
Experiment 46.
XII Food Analysis
Experiment 47.
Experiment 48.
Experiment 49.
XIII Food Adulterants
Experiment 50.
Experiment 51.
Experiment 52.
XIV Food Values
Experiment 53.
XV Leavening Agents
Experiment 54.
Experiment 55.
XVI Textiles
Experiment 56.
Experiment 57.
Experiment 58.
Experiment 59.
Experiment 60.
Digestion of Starch
Digestion of Proteins
Adulterants in Milk .
Tests for Adulterants in Butter .
Adulterants in Jellies and Candies
Menu Making ....
Products of Yeast Fermentation
Baking Soda, Baking Powder
Cotton, Linen, Wool, and Silk
Textile Dyeing .
Removing Spots and Stains
Bleaching and Blueing
Soaps, Cleansing Powders .
Appendix
PAGE
99
101
103
105
Analysis of Milk . . . .108
Babcock Test for Butter Fat in Milk 111
Beverages — Tea, Coffee, Cocoa . 113
The Metric System
Temperatures ........
List of the Common Elements, Their Symbols, Atomic
Weights and Valences ......
The Weight in Grams of One Liter of Various Gases
Food Chemistry Outline . . . .
Digestion of Foods .......
Action of Digestive Juicer
Tables Showing Food Units Required Daily .
Tables of 100 Food Units
Special Solutions 169
110
US
120
122
123
125
128
130
132
135
138
141
142
143
143
144
157
158
159
161
SUGGESTIONS TO TEACHERS
As has been noted in the preface, this manual was not written
to fit any particular textbook, but simply to outline a course in
chemistry for girls. It has been found that any good up-to-date
book in elementary chemistry can be used throughout the year's
work. On the second term's work, however, it is well to give
some reference work from the books mentioned.
Most of the experiments can be performed in the double
laboratory period of 90 minutes. Some of the experiments are
short enough so that two experiments can be performed in one
day. A few experiments require more than one double period.
It has been our experience that a student will work to far
better advantage in the laboratory if the instructor will spend
five, or even ten, minutes at the beginning of the laboratory
period discussing the experiment, emphasizing in particular the
purpose of the experiment and the precautions to be observed.
With a beginning class of girls, until they know something of
laboratory technique, it is well to show just how the apparatus
in the experiment is set up.
The method of presenting the principles and just where and
when to introduce the theories of chemistry to a beginning class
of girls, varies with different teachers. There is an outline on
food chemistry in the appendix that may be helpful to the
students.
IMPORTANT SUGGESTIONS TO STUDENTS
1. Pay your laboratory fee. No student may be assigned
a desk in a chemical laboratory until this fee is paid. Your in-
structor will keep your receipt on file until you need it to present
for refund.
2. Provide yourself with the following : a rubber or oil-
cloth apron, the standard laboratory notebook, some mop
cloths, a cake of soap, one fourth of a cake of sapolio, and a
sponge.
3. If you break a piece of apparatus, make out a requisition
slip for a new piece and replace it.
4. Always keep your apparatus clean and your desk neat.
Good chemists are never slovenly.
5. Keep the sink in front of your desk clean. — Do not put
acids or strong bases in it without flushing it well. Do not put
matches, fats, oils, paper, pieces of sodium or potassium into the
sink, but use the waste jars provided.
6. Do not use more material than the amount specified. If
too much is taken of either a solid or liquid, throw the excess into
the waste jars ; never pour it back into the bottle.
7. Never lay the stopper of a reagent bottle down on the
shelf ; keep it in your hand and replace it when you are through.
8. Never taste reagents unless told to do so.
9. In case of accident see instructions on page xv ; if serious,
report to instructor.
10. Your notebook should be an honest record of your own
observations and conclusions.
xi
SAFETY RULES
1. Before a new experiment is begun at least ten minutes should
be spent in the lecture room :
a. To emphasize precautions to be observed in order that
the experiment may be absolutely safe.
b. To make clear the purpose of the experiment.
c. To make the method clear.
2. Experiments missed by a student are not to be made up in
the laboratory unless carefully supervised by the instruc-
tor.
3. Have no materials on the distributing shelves except the
materials for the experiment of the day.
4. All other supplies should be kept in the storeroom and the
storeroom kept locked.
5. Poisons and materials not safe in the hands of students such
as potassium cyanide, phosphorus (yellow), sodium,
potassium, carbolic acid, and mercury salts, should be
locked in a special cupboard.
6. In the preparation of oxygen be sure that the manganese
dioxide is free from carbon before it is mixed with the
potassium chlorate. The teacher should perform the
experiment in front of the class before allowing them to
do it.
7. Such substances as potassium chlorate, phosphorus, sodium,
potassium ammonium nitrite, concentrated sulfuric acid,
and concentrated nitric acids are not safe in the hands of
the students in the crowded classes of the High School.
Experiments involving the use of these substances should
be performed by the instructor,
xiii
XIV SAFETY RULES
8. Other experiments in which poisonous gases are prepared,
such as chlorine, bromine, or phosphine, should be per'
formed by the teacher.
9. Unless the class is so small that the teacher can personally
direct each student, the experiment on the preparation
of hydrogen by any method should be performed b}^ the
teacher.
10. All experiments involving reductions by means of hydrogen
or the burning of hydrogen should be performed by the
teacher.
11. Keep your first-aid closet well stocked.
12. Carry all acid bottles with both hands, one on the bottom,
one holding the neck. Carry one bottle at a time.
LABORATORY FIRST AID
1. Accidents, if serious, should be reported to the instructor.
2. Cuts. Wash in running water, then with a piece of absorbent
cotton saturated with iodine solution. Bandage to prevent
contamination.
3. Burns caused by hot objects. Cover with a paste made by mixing
sodium bicarbonate and carron oil (equal parts of olive oil and
lime-water). Then cover with cotton and bandage.
4. $urns caused by acids. Wash with water, apply a solution of
sodium bicarbonate, then treat as in 2.
5. Burns caused by alkalies. Wash with boric acid, then treat as in 2.
G. Acids in eyes. Wash with water, then dilute solution of sodium
bicarbonate, then olive oil. Do not rub.
7. Bases in eyes. Wash with water, then boric acid solution, then
oil. Do not rub.
8. Other substances in eyes. Use water, boric acid, then oil. Do
not rub.
9. If a chemical is swallowed call a physician. Meanwhile, give
emetic of mustard and warm water. Consult " First Aid " for
antidote.
10. If irritating gases are inhaled — breathe fresh air. In case of
hydrogen chloride, sulphur dioxide, chlorine, or bromine, a very
dilute solution of ammonium hydroxide sniffed into the nose
often brings relief. If the gases are in the eyes, bathe with water
and boric acid. If overcome by hydrogen sulfide, inhale chlorine
gas (prepared quickly by treating powdered potassium chlorate
in a beaker with a few drops of hydrochloric acid at a time).
xv
HOUSEHOLD CHEMISTRY
PART I
FIRST TERM'S WORK
I. PRELIMINARY EXPERIMENTS
Upon entering the laboratory, hang your coat upon the
hooks provided, roll back your sleeves, put on your apron, and
check your apparatus with the following list. If anything is
missing or not in good condition, report to the instructor. After
the first day, broken or lost apparatus will be charged to your
account.
APPARATUS LIST
1 Asbestos mat $0.10
1 Beaker, 150 cc 35
1 Beaker, 250 cc 40
1 Crucible, porcelain, #0 . . . . .35
1 Clay triangle 05
1 Cover for crucible, #0 15
1 Delivery tube, rubber, 18" 25
1 Elbow glass, 3" X 6" 05
1 Elbow glass, 3" X 3" 05
1 Evaporating dish, porcelain, 50 cc 30
1 Forceps, steel, 5" 15
1 Flask, Florence, 250 cc 25
1 Funnel, short stem, 3" diameter 30
4 Gas bottles, wide mouthed, each ,N . . . .15
4 Glass plates (cover glasses), each 10
1
2 PRELIMINARY EXPERIMENTS
1 Graduate (measuring cylinder), 50 cc 75
12 Gas testers, wooden splints 05
1 Box matches, safety
3 Rubber connectors (3" rubber tubing) 10
1 Stirring rod 05
1 Stopper, 1-hole, pure gum 10
1 Stopper, 2-hole, pure gum 10
1 Test tube, side neck, 8" XI" 20
12 Test tubes, 6" X|" each 05
1 Test tube, 8" XI" 10
1 Test tube brush 15
1 Test tube holder (bent wire) 15
1 Thistle tube, straight stem (safety) 60
2 Watch glasses, 2" 05
1 Wire screen, 4" X 4" 10
PERSONAL LIST
Apron, cloths, sponge, soap, sapolio, paper.
After checking your apparatus, fold and put away your apron
and lock the drawer and locker. Keep your key.
EXPERIMENT 1
The Buns en Burner
Apparatus. Bunsen burner, matches, beaker, test tube, test
tube holder, wire screen.
Note to student: When you enter the laboratory, put on your apron and
begin the experiment at once. Work independently unless otherwise in-
structed. Do not waste time. Unfinished experiments will have to be
finished after school. Put your name, the date, the number of the experiment
at the top of a page in your notebook and record carefully each observation
as you work. Be sure to have the instructor sign your notes before you leave
the laboratory. Always bring your laboratory notebook with you on recitation
days in order that the experiment just performed may be discussed.
Note to teacher : Much time will be saved if the parts of the Bunsen burner
are briefly explained before the students enter the laboratory. Also show
how to heat a liquid in a test tube and how to use a ring stand.
THE BUN SEN BURNER 3
A. The Parts of the Burner.
The Bunsen burner is a form of apparatus used for the
burning of gas. It is the usual source of heat in the labora-
tory. The name " Bunsen " has been given to the burner
because it was first made by the German scientist Bunsen.
It consists of a base and a tube which has two round openings
in its lower part, through which air enters. A small band,
with corresponding openings, fits the lower part of the tube,
and by turning this the holes in the tube may be kept open
or closed. The gas enters by means of a rubber tubing
through the base. It mixes with the air that enters the
openings in the tube and is burned at the top of the tube.
1 . Unscrew the tube of the burner and examine the parts.
Draw each part and label it. Put it together again and light
the gas. To do this light a match and hold it about two
inches above the end of the tube, then turn on the gas. If
a burner " strikes back " and burns at the base, shut off
the gas and light again. The flame should not be more than
four inches high at any time.
2. Shut off the air by closing the holes at the base. What
happens to the flame? Open the holes again and admit
air. Which flame is best for laboratory work ? Why? Put
one of your splints into the base of the blue flame and
gradually raise it. What part of this flame is the
hottest ?
B. How to Heat Glass Apparatus in the Bunsen Flame.
1. To heat ivater in a test tube. Half fill a test tube
with water, wipe the surface dry. Place the test tube clamp
about the top of the test tube, as directed by the instructor.
Incline the tube away from your face, but not toward your
4 PRELIMINARY EXPERIMENTS
neighbor. Apply the heat near the top of the liquid. Move
the tube about in the hottest part of the flame, so that it
may be uniformly heated. When the water boils, pour it
into the sink and put the tube away.
2. To boil a beaker of water. Place a wire screen on the
ring of your ring stand. Place the burner under the screen
and adjust the ring so that the screen presses down about one
inch of the flame. (Note the instructor's model.) Half
fill the beaker with water, wipe the surface dry, and place
it on the screen. If the beaker were heated without the
screen, it would probably break. How does the screen
prevent this ?
C. Before Leaving the Laboratory.
Wash your apparatus and put it away. Be sure to put
away your screen. Put the burnt matches and other scraps
into the jars. Wipe the desk top with a cloth. Clean up
in this way after every experiment hereafter. Be sure to
lock your drawer and locker. The instructor must sign your
notes before you leave the laboratory. Bring these with
you at the next recitation.
EXPERIMENT 2
The Units of Length, Volume, and Weight Used in Chemistry
Reference. Appendix in this manual.
Apparatus. A meter stick, a short metric ruler, flasks represent-
ing 1 1., 500 cc, 250 cc, 100 cc, balance.
Note to student: Take careful notes. Number and letter the paragraphs
in your notes to correspond to the paragraphs in the manual. If you do not
understand the directions, ask the instructor for help. Have your notes
signed before leaving the laboratory. Bring the notes for discussion at the
next recitation.
THE UNITS OF LENGTH, VOLUME, AND WEIGHT 5
A. Unit of Length.
The unit of length most often used in chemistry is the
centimeter. Examine a meter stick and notice that a meter
is more than a yard long. How many inches are there in the
meter stick ? How many centimeters in the meter ? Draw
a line one centimeter long and write the abbreviation 1 cm.
over it. How many millimeters in a centimeter? Divide
the line you have just drawn into millimeters. What is the
abbreviation for a millimeter? Using the small ruler
measure the length of your Bunsen burner tube in centi-
meters ; the diameter of the tube. Measure the length and
diameter of a test tube and your beaker.
B. Unit of Volume.
The cubic centimeter is the unit most often used. Its
abbreviation is cc. Draw a cube with each edge one centi-
meter long. This represents a volume of one cubic centimeter.
There are one thousand cubic centimeters in a liter. Ex-
amine flasks with capacities of 1 1., 500 cc, 250 cc, and 100
cc, respectively. From the size of your flask, as compared
with these, what do you think is its volume ? Measure 1 cc.
of water in your graduated cylinder ; measure 50 cc. (Read
the lower part of the curved surface always.) Now, using
the graduate, fill the flask and measure its volume. In like
manner measure the volume of your beaker and test tube.
C. Unit of Weight.
The gram is the common unit of weight. Its abbreviation
is g. Imagine the cube you have drawn in B to represent
one cubic centimeter filled with water. The weight of this
water would be about one gram. There are one thousand
grams in a kilogram. If one cubic centimeter of water
6 PRELIMINARY EXPERIMENTS
weighs one gram, how many grams of water will your flask
hold ? your beaker ? your test tube ? Learn how to use the
balance, then weigh your beaker.
Note : Return the meter sticks and rulers to the distributing table. Put
away your apparatus. Clean and lock your desk as usual.
D. Problems.
1. A tank is 500 cm. long, 200 cm. wide, and 90 cm. deep.
How many cubic centimeters of water will it hold ?
2. If one cubic centimeter of water weighs one gram,
how many grams of water will the tank in problem 1
hold?
3. A potato weighs 9 ounces. How many grams does it
weigh ?
4. What is your own weight in kilograms?
EXPERIMENT 3
How to Make Simple Apparatus from Glass Tubing
Materials. Soft glass tubing, external diameter 5 mm. or 6 mm.
(about 1 of an inch).
Apparatus. Triangular file, fish-tail attachment for the Bunsen
burner, meter stick or ruler, a Bunsen burner.
Note to student: The laboratory notes will be mere statements of what
you did.
Note to teacher: Before entering the laboratory, show the students how
to cut, bend, round sharp edges, and seal glass tubes.
A. To Make a Glass Elbow or Delivery Tube.
Glass elbows or delivery tubes are simple pieces of appa-
ratus used to conduct gases from one vessel to another. To
make a short one : (1) Cut off a piece of glass tubing 15
HOW TO MAKE SIMPLE APPARATUS FROM GLASS TUBING 7
cm. long (about 6 inches). (2) Bend at right angles in the
middle and (3) smooth each end. Follow the instructor's
directions as closely as possible.
1. To cut a glass tube, place it on the table, measure off
the required length, and at this point make a scratch with
the triangular file. Pick up the tube with both hands.
Place thumbs on both sides of the scratch and opposite it.
Press up with the thumbs and down with the hands. The
break should be even.
2. To bend a glass tube, hold it lengthwise in the flat
flame produced by the fish-tail attachment. Rotate it con-
stantly until it is soft, then take it from the flame and bend
it at right angles. Hold it so until it hardens. The bend
should be smooth. Show it to the instructor for approval or
advice before making a new one.
3. The elbow cannot be used as it is because the sharp
ends would cut the rubber stopper. Make each end smooth
by heating it in the ordinary Bunsen burner flame till the
glass begins to melt slightly.
4. Make a long, glass elbow in the same way, using about
30 cm. of tubing, making the bend about 8 cm. from
one end. This also should be approved before it is put
away.
B. To Make a Stirring Rod.
Cut off a piece of glass rod about 25 cm. in length. Heat
the ends in a Bunsen flame till they are soft and round.
Place it on the iron base of your ring stand to cool. Never
put any hot glass or hot apparatus on the top of the table.
After your rod has been approved put it away. Have your
notes signed.
8 PRELIMINARY EXPERIMENTS
EXPERIMENT 4
Physical and Chemical Changes
Materials. Granulated cane sugar.
Apparatus. Beaker, test tube, mortar and pestle, Bunsen burner,
ring stand, wire screen, test tube holder.
Note to teacher : It is convenient to measure out the proper amount of
material on squares of paper on the distributing table ready for the students.
This saves a great deal of time and material.
A. How Sugar May Be Changed.
1. Take a clean dry test tube and obtain about 10 grams
of sugar from the distributing table. (Note : Be careful not
to spill material on the distributing table — if you do, clean
it up. Hold the stopper of the bottle in your hand and re-
place it when you are through.) Carefully note the proper-
ties of the sugar, its crystalline form, its hardness, color, and
taste. How could you distinguish it from table salt ? What
then is its most characteristic property ?
2. Put about half of your sugar in a clean mortar and grind
it till it is a powder. Taste it. Is it still sugar? Has its
characteristic property been changed by grinding? This is
a physical change, because the composition of the substance
is unchanged, as is shown by the fact that no change in the
characteristic properties has occurred.
3. Fill your beaker one fourth full of water and add the
powdered sugar from the mortar. Stir with your stirring
rod until the sugar is dissolved. Taste the solution. Has the
sugar been destroyed? What has happened to it? This is
a physical change.
4. Heat the remainder of the sugar in a dry test tube
until it stops smoking. Note every change carefully. When
ELEMENTS, COMPOUNDS, MIXTURES 9
no further change takes place, cool the tube, break it, and
examine the substance remaining in the tube. What is its
form, its hardness, color, and taste? Will it dissolve in
water ? Try it. Has the substance any properties of sugar ?
This is a chemical "> change, because the composition is
changed and a new substance is formed, having new prop-
erties.
B. How Other Substances May Be Changed.
Tear a piece of paper into bits. Is the change physical
or chemical? Why? Burn a piece of paper. Describe
the change. Is it a physical or a chemical change ?
C. Some Changes We See Every Day.
Are the following changes physical, or chemical, or both?
Give a reason for your answer in each case. 1. The souring
of milk. 2. Making a batter from flour, milk, and eggs.
3. Baking bread. 4. Making candy. 5. Beating an egg.
6. Boiling an egg. 7. Freezing cream in making ice cream.
8. Tarnishing of copper.
Note : Have your notes signed.
EXPERIMENT 5
Elements, Compounds, Mixtures
Materials. Sulfur, about 5-gram portions, magnesium ribbon,
3 cm. strips, mixture of equal parts powdered sugar and sulfur,
10-gram portions, Shaker Salt 10-gram portions.
Apparatus. Evaporating dish, forceps, Bunsen burner, filter
paper, funnel, stirring rod, two beakers.
Note to teacher : Before entering the laboratory, show how to fold a filter
and the correct method of filtering.
Note to student: Take careful notes and have them signed before leaving
laboratory.
10 PRELIMINARY EXPERIMENTS
A. Elements.
1. Obtain 5 grams of sulfur in a test tube. Examine it
carefully. What are its chief physical properties, i.e. color,
odor, taste. Try to dissolve a little in a test tube half full
of water. Is it soluble in water? Is sulfur a metallic or a
non-metallic element? Can you find in the Appendix the
names of three common non-metallic elements?
2. Obtain a piece of magnesium ribbon about 3 cm. long.
Notice its color and weight, its luster, and its flexibility. Is
it a metallic or a non-metallic element ? Give the names of
three common metals and give a use for each.
3. Repeat 2, using aluminum instead of magnesium.
4. Now tell in your own words what an element is.
B. Compounds.
1. Place a little sulfur about the size of a pea in your
evaporating dish. Heat the sulfur by means of the burner
flame till it burns. Very carefully note the odor. Is this
a physical or chemical change ? We have noted the physical
properties of sulfur in A, 1 . We have now observed one
chemical property of sulfur. What is it? The gas that is
formed when sulfur is burned is sulfur dioxide. It is a com-
pound.
2. By means of the iron forceps hold the piece of mag-
nesium ribbon in the flame. Result? What is formed?
Has the new compound any of the properties of the metal
magnesium or the gas oxygen from which it was formed?
In general, what is formed when an element burns in the air?
Give a chemical property of magnesium.
3. Repeat 2, using aluminum instead of magnesium.
What is formed? Give a chemical property of aluminum.
ELEMENTS, COMPOUNDS, MIXTURES 11
4. Is sugar an element or a compound? How did you
prove this in the preceding experiment? What is one ele-
ment in it? Consult the textbook and find out the other
elements in sugar. What are the elements in table salt
(sodium chloride) ? in water ?
5. What is a compound ?
C. Mixtures.
1. A well-known remedy for sore throat consists of a mix-
ture of equal parts of sulfur and powdered sugar. Obtain
from the instructor about ten grams of this remedy in your
beaker. Fill the beaker half full of water and boil for about
one minute, stirring occasionally. Which constituent of
the remedy will dissolve? Which one will not? Remove
the beaker from the ring stand and filter. The solid will
remain on the paper and the liquid will pass through it.
To prepare a filter paper fold it once and then again at
right angles to the straight edge. Open the paper as a cone,
with a triple layer of paper on one side and a single layer on
the other. Place it in the funnel and moisten it well with
water. The paper should not come to the top of the funnel.
Place the funnel in the ring of the ring stand. Place the
other beaker under the funnel. Adjust the ring so that
the stem of the funnel extends into the beaker about one
inch. To pour the liquid from the beaker into the funnel
without spilling it hold the glass rod lightly against the rim
of the beaker. -The liquid will flow down the rod. The
liquid that goes through the filter paper is called the
filtrate.
Taste the filtrate. Where is the sugar? Where is the
sulfur ? If a mixture consists of two substances, one soluble
12 OXYGEN AND HYDROGEN
in water and one insoluble, what is the general method of
separating them ?
2. "Shaker Salt" is pure sodium chloride (table salt) to
which has been added a little starch to keep it dry. Starch
is not soluble in water. Obtain ten grams of "Shaker
Salt." Stir it into half a beaker of cold water. Is starch
present ?
3. Now define a mixture clearly.
II. OXYGEN AND HYDROGEN
EXPERIMENT 6
Ways of Freeing and Collecting Oxygen
Materials. Powdered potassium chlorate 8-gram portions,
splints (about the size of a match and 7 inches long),
powdered manganese dioxide 2-gram portions.
Apparatus. Bunsen burner, test tubes, gas bottles, pneumatic
trough, glass plates.
A. How to Obtain Oxygen.
1. Oxygen is the gas in the air which makes a fire burn.
The air would be an excellent source of oxygen if it did not
have so much nitrogen mixed with it. It is difficult to re-
move the nitrogen and leave the oxygen.
2. The compound potassium chlorate, KCIO3, is the most
convenient source of oxygen. Obtain 8 grams of powdered
potassium chlorate and 2 grains of manganese dioxide.
Divide the potassium chlorate into two equal parts. Put
one part (4 grams) in a clean, dry test tube. Mix the other
part (4 grams) on a piece of paper with 2 grams of manganese
dioxide (half as much), using the stirring rod. Then put
it into a clean, dry test tube of the same size as the first.
WAYS OF FREEING AND COLLECTING OXYGEN 13
3. Heat the first tube gently and with a glowing splint
test for oxygen. If oxygen is present, the glowing splint will
burst into flame. Now heat the tube intensely and test for
oxygen. What effect has increased heat? When oxygen is
no longer given off, a new compound, potassium chloride,
remains in the tube.
4. Now heat the second tube containing the mixture of
potassium chlorate and manganese dioxide.
Important: If this mixture sparks (gives flashes of light), call the instructor
to look at it. It means that the manganese dioxide contains carbon and is not
safe to use in the next experiment. Small sparks are due to dust.
Test with the glowing splint as before. The manganese
dioxide undergoes no change. It causes the potassium
chlorate to give up its oxygen at a lower temperature. It
increases the speed of the reaction. What is such a sub-
stance called? (Consult your textbook.) When oxygen is
given off no longer, what is left in the test tube ?
Note : To clean the test tubes in 3 and 4 fill them with water and let
them stand overnight.
B. How to Collect Oxygen and Other Gases.
1. The most convenient method to collect a gas is by dis-
placing water. Obtain a pneumatic trough and half fill it
with water. Fill one of your gas bottles with water and slip
a glass plate over the mouth, being careful to exclude all air
bubbles. Hold the plate in place, invert the bottle in the
water, and remove the plate. Raise the bottle a little ; never
lift the mouth of the bottle out of water. Why does the
water stay in the bottle? Hold the bottle in this position
and fill it with air from the lungs by inserting one end of a
rubber delivery tube in the mouth of the bottle and care-
fully blowing through the other end.
When the bottle is full of gas, cover its mouth with a glass
14 OXYGEN AND HYDROGEN
plate (still under water), remove from the water, and place
it on the desk. A bottle of gas so covered is placed right
side up if the gas is heavier than air, or upside down if the
gas is lighter than air.
2. A liter of air weighs 1.29 grams. A liter of oxygen
weighs 1.43 grams. (See Appendix.) How then should a
bottle of oxygen be placed ?
3. A liter of hydrogen weighs .09 gram. Would you
place the bottle upside down or right side up in this case in
order to keep the hydrogen in the bottle the longest possible
time?
4. The gas carbon dioxide is soluble in water. It is heavier
than air. How would you collect it ? How place the bottle ?
5. The gas ammonia is also very soluble in water. It is
lighter than air. How would you collect it? How place
the bottle?
EXPERIMENT 7
Preparation and Properties of Oxygen
Note to teacher: Each student understands that work in the laboratory
must be done alone unless otherwise directed by you. Unless the laboratory
periods are very long it has been found more satisfactory to allow two students
to work together on this experiment. Discuss the experiment briefly and show
how the apparatus is set up before students enter the laboratory. Place the
" set up " in the laboratory so that they may use it as a model.
Materials. 20 grams powdered potassium chlorate and 2
grams of manganese dioxide mixed, pine splints, sulfur 1-
gram portions, iron picture wire 15 cm. long.
Apparatus. Pneumatic trough, four gas bottles (about 250 cc.
each), four cover glasses, rubber delivery tube, short glass
elbow, rubber stopper to fit large, hard-glass test tube, Bunsen
burner, ring stand, test tube ciamp, combustion cup.
PREPARATION AND PROPERTIES OF OXYGEN 15
A. Preparation of Oxygen — Laboratory Method.
1. Fill the pneumatic trough about half full of water.
Fill four gas bottles with water, cover them, and invert in the
trough as directed in Experiment 6, B. If a bottle has an
air bubble, fill it again and invert.
2. Attach the rubber delivery tube to the short glass
elbow, put the elbow into the one-hole stopper, and fit the
stopper into the large, hard-glass test tube. If it does not
fit well, exchange it for one that does. All joints must be
tight or the oxygen will escape into the air. Attach the
test tube clamp to the ring stand and support the test tube
in a slanting position. Do not pinch the tube tightly or it
will break when you heat it.
3. Obtain a mixture of 20 grams of potassium chlorate
and 2 grams of manganese dioxide. Put into the hard-glass
test tube, replace the stopper, and heat the mixture gently,
at first holding the burner in the hand and moving the flame
up and down on the tube. Put the end of the delivery tube
in the water. The first bubbles are small and irregular
bubbles of air. Soon large bubbles of oxygen should be
evolved. Heat more gently if the gas comes too rapidly.
Collect four bottles of gas.
Caution : Remove the delivery tube before you stop heating or the water
will be drawn back into the hot test tube and break it. Why will the water be
drawn back in this way ?
4. What substance produced the oxygen? Why was
the manganese dioxide used? Write in words the equation
for the reaction that took place thus :
Potassium Chlorate + heat — ^Potassium Chloride + Oxygen
KC103 +heat— >■ KC1 +30
16 OXYGEN AND HYDROGEN
Since the manganese dioxide was not changed in any way, it
would not appear in the equation.
B. Physical Properties of Oxygen.
The physical properties of a gas are its color, odor, taste,
its solubility in water, and its weight as compared with air.
1 . Uncover a bottle of oxygen, smell it, and inhale some of
it through the mouth. Has it any odor or taste? Has it
any color? Is it soluble in water? Is it heavier or lighter
than air? Recall Experiment 6, B, 2.
2. Summarize the physical properties of oxygen.
C. Chemical Properties of Oxygen.
Chemical properties are those that are shown where a
substance undergoes a chemical change.
1. Thrust a glowing splint into a bottle of oxygen. Re-
move it, blow out the flame, and thrust it in again. Do this
as many times as you can. After a while the stick will not
burst into flame. Why? Does oxygen burn? Does it
support combustion (make other things burn) ? What gas
is now in the bottle? WTas this a physical or chemical
change? Write in words the equation for the reaction.
2. Obtain 1 gram of sulfur in your evaporating dish.
Place half of this in your combustion cup. Hold it over the
flame until it starts to burn. Notice the color and size of
the flame. What is the gas formed when sulfur burns in
air or in oxygen? Thrust it quickly into a bottle of oxygen.
Notice the change in the flame. What is the gas formed?
Write the equation in words to show what took place. Was
this a physical or chemical change ?
3. Fray one end of a piece of iron picture wire. Heat the
frayed end and then dip it into the sulfur in your evaporating
WHAT TAKES PLACE WHEN A SUBSTANCE BURNS 17
dish. The wire is frayed and dipped in sulfur in order that
it may start to burn more readily. Hold the wire in the
flame till the sulfur burns, then thrust it into a bottle of oxy-
gen. Result? Will iron burn in the air? What new sub-
stance was formed in the bottle? What kind of change
took place? Write in words the equation for the reaction
that took place. When a substance burns in oxygen, what
is always formed ?
4. From these tests what is the chief chemical property
of oxygen ?
Note: Empty the pneumatic troughs and return them. Burn the sulfur
out of the combustion cup before returning it.
EXPERIMENT 8
What Takes Place When a Substance Burns
Note : This should be a class experiment if hoods are not available or if the
class is large. It is a dangerous experiment.
Materials. Yellow phosphorus, red phosphorus, sulfur (small
amounts about the size of a pea), sulfur matches, parlor matches,
safety matches.
Apparatus. Bunsen burner, asbestos mat, forceps.
A. Slow Oxidation.
1. Half fill your evaporating dish with water and take
it to the instructor for a piece of yellow phosphorus the size
of a pea. Lift it out of the dish with the forceps and place
it upon your asbestos mat. Take Care ! Do not Touch
It with the Fingers. What are its physical properties?
As soon as the phosphorus becomes dry, do heavy white
fumes arise? What are these fumes? Do you notice any
light or heat ? What is taking place ?
18 OXYGEN AND HYDROGEN
2. When iron rusts, what is formed ? Is there any notice-
able light or heat ? What is this process called ?
B. Rapid Oxidation or Burning (Hood).
1 . Carefully place a small amount (about the size of a pea)
of sulfur one inch from the phosphorus. About the same
distance away place a small amount of red phosphorus.
The same distance away place a piece of pine splint. Raise
the temperature of all by slowly heating with the burner
turned low. Stand back and observe the order in which
the substances take fire and burn.
2. Explain what takes place when a substance burns in
the air.
3. What is meant by the kindling temperature of a sub-
stance ?
4. Why is phosphorus kept under water?
5. Why was the untwisted picture wire tipped in sulfur
before putting it in oxygen to burn ?
6. Why are paper and kindling wood used to build a coal
or wood fire ?
7. Lacking kindling wood, kerosene is sometimes poured
upon the coal or wood. Is this safe? Why?
C. The Study of Matches.
1. Examine the head of a sulfur match. The color, usually
red, is merely a dye. Rub the head upon your moist hands
in the dark. What causes the glowing streak? Smell the
match head after rubbing it on your hand. W7hat is in the
tip of the match? Remembering the color of sulfur, see if
you can observe sulfur on the wood next to the match head.
Rub a match on a rough surface. What takes fire first?
What produces the heat to raise it to its kindling tempera-
PREPARATION AND PROPERTIES OF HYDROGEN 19
ture ? What burns last ? What produces the heat to make
it catch fire? Name in order the substances in a sulfur
match that burn, beginning with the one that has the lowest
kindling temperature.
2. Examine a parlor match in like manner. What is used
in place of the sulfur in this match? Name in order the
substances in a parlor match that burn, beginning with the
one that has the lowest kindling temperature.
3. WThat is a safety match? Why is it safe? Where
must it be scratched ?
Caution: Be sure that all of the phosphorus is burned from your mat before
you put it away. See that no phosphorus clings to the forceps. If you have
any unused sulfur matches or parlor matches, return them ; it is not safe
to put them away in the drawer or locker.
EXPERIMENT 9
Preparation and Properties of Hydrogen
Note to teacher : Before the students enter the laboratory discuss the ex-
periment briefly and show how the apparatus is set up. Leave your " set up"
before them as a model. Supervise closely, to avoid explosions.
Materials. Granulated zinc 10-gram portions, splint, dilute
sulfuric acid.
Apparatus. A 250-cc. Florence flask, two-holed stopper, short
elbow, delivery tube, pneumatic trough, four gas bottles, beaker,
two test tubes, and a safety tube.
A. The Usual Method of Preparing Hydrogen by Action of a Metal on
an Acid.
1. Carefully slip 10 grams of zinc into your flask; insert
the stopper containing the safety tube and delivery tube.
Keep the flask in an upright position by clamping it to the
ring stand. Half fill the pneumatic trough with water and
invert in it four gas bottles filled with water, as in the case of
20 OXYGEN AND HYDROGEN
oxygen. Have the four cover glasses near the trough ready
for use when the bottles are full. Also fill two test tubes
with water and invert them in the trough. (They may lie
in the water on the bottom of the trough till you are ready
for them.) Remove the stopper from a bottle of sulfuric
acid by grasping it between the first two fingers of the right
hand, palm up. Pick up the bottle with the same hand and
pour acid into the thistle tube. Just touch the mouth of
the bottle to the lip of the tube. Pour in acid till the zinc is
covered. Then replace the bottle and the stopper. Always
follow these directions when pouring a liquid from a bottle.
Never put the stopper on the table or shelf, and if too much
liquid is taken, never return any to the bottle. Keep it in a
labeled test tube for future use or throw it into the sink.
If hydrogen comes from the acid very slowly, add through
the thistle tube 5 or 10 cc. of copper sulfate solution. Why
does this increase the action? Be sure that the apparatus
is air tight.
2. Light the Bunsen burner. Caution ! Keep it some
distance from the apparatus, because at first the hydrogen
is mixed with air and the mixture is explosive.
3. Allow the gas to escape into the air for about one
minute, then collect a test tube of it. Put the thumb over
the mouth of it and bring the tube, mouth downward, to
the flame. If it explodes, the hydrogen is still mixed with
air. Collect another test tube and try again. When the
gas burns with a little puff at first, it is ready to be collected
in the gas bottles. Collect four bottles of hydrogen ; cover
them and invert them on the desk. If the action stops before
the bottles are filled , add a little more acid. Why remove
the deliverv tube from the water ?
PREPARATION AND PROPERTIES OF HYDROGEN 21
4. Where does the hydrogen come from? What was the
use of the zinc ? Could any other metal have been used ?
B. Physical Properties of Hydrogen.
1 . Examine a bottle of hydrogen ; note its color, taste,
and odor. (There may be a slight odor due to an impurity.)
2. Is it soluble in water? How do you know?
3. Uncover a bottle of hydrogen ; hold it mouth upward
while you count thirty, then test for hydrogen. Explain the
results. Is the gas heavier or lighter than air?
C. Chemical Properties.
Hold a bottle of hydrogen mouth downward and quickly
thrust a blazing splint into the bottle. Withdraw the splint
and insert it again. Does the hydrogen burn ? If so, where ?
Does the splint burn when in the bottle? when out of the
bottle? Does hydrogen support combustion? Feel the
neck of the bottle. Describe and explain. What proper-
ties of hydrogen are shown by this experiment ?
D. What Remains in the Flask.
1. Pour the liquid from the flask into a beaker. Return
the pieces of zinc to the instructor. Put the beaker in the
locker until the next laboratory period. Then examine the
contents of the beaker. What are the crystals? Did a
physical or chemical change take place ?
2. The equation for the reaction is as follows :
Sulfuric Acid + Zinc — >- Zinc Sulfate + Hydrogen
H2S04 + Zn — >■ ZnS04 + 2H
Hereafter, all equations will be written in this manner —
first in words, then using formulas for the compounds and
symbols for the elements. What are the compounds in the
22 OXYGEN AND HYDROGEN
reaction ? Name each, and give the formulas for each.
What is the metallic element? Give its symbol. What is
the non-metallic element? Give its symbol.
EXPERIMENT 10
(Class Experiment)
Two Other Methods of Preparing Hydrogen
Note : In A 4 be sure that the tin foil is wrapped so tightly about the sodium
that no air is included or an explosion may result.
Materia.". Sodium, potassium, sulfuric acid, distilled water.
Apparatus. Pneumatic trough, knife, tin foil, iron or copper
wire, 250 cc. gas bottle, glass plate, Hoffman apparatus, stor-
age battery.
A. By the Action of Metals on Water.
1. Note the physical properties of sodium and potassium.
2. Cut off a piece of sodium the size of a pea and throw it
upon the water in the pneumatic trough. What is the re-
sult? Explain.
3. Repeat, using potassium instead of sodium. Note the
results. Explain.
4. With the sharp end of a file punch small holes in a
piece of tin foil and wrap it firmly around a piece of sodium
about the size of a large bean. Fill a 250 cc. gas bottle with
water and invert it in the trough. Raise the bottle slightly
and by means of a wire quickly thrust the sodium under
the mouth of the bottle. When the bottle is full of gas, con-
tinue to hold the sodium under water till the action ceases.
Then cover the bottle with a glass plate and remove from the
water. Bring a flame to the bottle and uncover it. Explain
the results.
TWO OTHER METHODS OF PREPARING HYDROGEN 23
5. What is the gas? Where did it come from? Why
was the flame colored yellow in this case? Now explain
the flame when potassium was thrown on the water.
6. What method of preparing hydrogen is shown by this
experiment? What is one of the elements in water?
7. Test the water with pink litmus. What is dissolved
in the water? Write a word-and-symbol equation to show
what has taken place.
B. By the Action of the Electric Current on Water.
1. Fill a clean Hoffman apparatus with pure distilled
water. Connect the platinum terminals with an electric
battery. Is a gas given off at either terminal? Does pure
water conduct an electric current ?
2. Fill the Hoffman apparatus with water containing 10
per cent of sulfuric acid, so that the water in the reservoir
tube stands a short distance above the gas tubes after the
stop-cock in each has been closed. Connect the platinum
terminal wires with the battery. Allow the current to oper-
ate until the smaller volume of gas is from 8 to 10 cm.
in height. Measure the height of each gas column.
3. Hold a glowing splint over the tube containing the
smaller quantity of gas. What is the gas that collects at the
positive electrode (anode) ? Open the other stop-cock to
force out the water in the glass tip, then hold a lighted match
at the end of the tip. What is the gas that collects at the
negative electrode (cathode) ? Make a drawing showing
the anode and cathode and the relative volume of gases col-
lected over each.
4. If the current were allowed to flow long enough, all the
water would be used up. The sulfuric acid would remain.
24 WATER
What is the use of the sulfuric acid ? Could any other sub-
stance have been used?
5. What does this experiment show about the composi-
tion of water? Write the word-and-symbol equations to
show what takes place on the electrolysis of water.
6. In what three ways may hydrogen be prepared?
7. In what four ways have you prepared oxygen ?
III. WATER
EXPERIMENT 11
(Class Experiment)
The Synthesis of Water
Materials. Calcium chloride, copper oxide, wire form.
Apparatus. Hydrogen generator, calcium chloride tube, de-
livery tube, clay pipestem, bell jar, hard glass combustion
tube 7 inches long.
A. Synthesis of Water by Burning Hydrogen.
1. Connect a calcium chloride tube with a hydrogen gen-
erator (a Kipp generator is best). How is the hydrogen
generated? Why is the calcium chloride tube used? All
joints must be air-tight. Attach a delivery tube to the cal-
cium chloride tube, and collect a test tube full of hydrogen
by displacement of water. If it burns quietly, remove the
delivery tube and attach a platinum jet or a clay pipestem
jet. Why test the gas before it is lighted? Allow the hy-
drogen to pass for a full minute and then hold a bell jar
over the tip. Note any change.
2. Remove the jar, light the hydrogen, and again hold
the bell far over the jet. Note any change in the jar.
HOW TO TEST HYDROGEN AND WATER 25
3. What is formed when hydrogen burns in the air? Of
what elements is water composed? Write the word-and-
symbol equation to show the change that takes place.
B. Reduction and Oxidation.
1 . Use the same apparatus as in A. Attach to the calcium
chloride tube a straight glass tube and extend this into a hard-
glass test tube containing 1 gram of copper oxide, wire form.
2. When the apparatus is free from air, heat the copper
oxide, being careful not to heat the top of the test tube.
3. WThat change takes place in the copper oxide? What
collects on the cool sides of the test tube ? Write the word-
and-symbol equation for the change that took place.
4. When oxygen or other non-metal is removed from a sub-
stance, it is called reduction. Is hydrogen a good reducing
agent in this case ? Why ?
5. When oxygen or other non-metal is added to a substance,
the process is called oxidation. Is copper oxide an oxidizing
agent in this case ? Why ?
6. What is meant by the word synthesis f In what two
ways was water synthesized in this experiment ?
EXPERIMENT 12
How to Test Hydrogen and Water
Materials. Pine splint, sugar, corn starch, alum crystal, crys-
tals of sodium carbonate, crystalline calcium chloride, potato,
meat, apple.
Apparatus. Bunsen burner, cold glass plates, test tubes.
A. Test for Hydrogen in Substances.
From Experiment 1 1 you learned that when hydrogen is
burned in the air, it combines with the oxygen of the air to
26 WATER
form water. If then water is formed when a substance is
burned in air, the substance must contain hydrogen.
1. Light the Bunsen burner. Hold a cold dry glass plate
over the flame. Note any moisture on the plate. Does
ordinary gas contain hydrogen ? Now explain why the cold
bottom of a kettle or a cold flatiron becomes moist when
they are first placed over a flame. Why does the moisture
disappear after a time ?
2. Why does the inside of a kerosene lamp chimney be-
come covered with moisture when the lamp is first lighted?
This moisture disappears in a few minutes. Why?
3. Burn a pine splint and hold a cold dry plate above the
flame. Does wood contain hydrogen ?
B. Test for Hydrogen and Oxygen in Substances.
Some substances v contain both hydrogen and oxygen.
When these substances are heated till they decompose, the
hydrogen in the substance combines with the oxygen in the
substance to form water. The substance must not be burned.
This test proves the presence of both hydrogen and oxygen
in a compound.
1 . Heat 5 grams of sugar in a dry test tube till it is com-
pletely decomposed. Keep the neck of the tube as cold as
you can and look for drops of water on the sides of the tube.
What are two elements in sugar? In what proportion are
these elements present in sugar ? Does sugar contain water ?
What remains in the test tube? Write a word-and-symbol
equation for the reaction that took place.
2. In like manner heat 5 grams of corn starch. Ex-
plain what takes place. Write the word-and-symbol
equation.
HOW TO TEST HYDROGEN AND WATER 27
C. Test for Water in Substances.
Many substances contain water held in such a way as to
give the substance its form. Water so held may be removed
by heating the substance gently without burning it or decom-
posing it.
1. Heat a crystal of alum in a dry test tube. Is water
given off? What happens to the crystal?
2. Heat a crystal of sodium carbonate (washing soda)
in the same way. Result? When crystals of sodium car-
bonate are exposed to the air they give up water to the air
and they fall to a powder. Wliat is this process called?
Would it be cheaper to buy clear crystals of washing soda or
to buy the substance after it has become a powder from long
standing in the air? Why?
3. Heat a crystal of calcium chloride in a dry test tube.
Result? Now leave exposed to the air some calcium
chloride which has been so heated. Result? Explain:
Why does ordinary table salt sometimes become moist and
hard to shake from the salt cellar? What is sometimes
added to prevent this?
4. Nearly all foods and substances of plant and animal
life contain water. Heat in a cool dry test tube portions
about the size of a bean of the following substances. Be care-
ful not to burn or decompose the substances.
1.
Wood
2.
Potato
3.
Meat
4.
Apple
5.
Nut
What
do
you
conclude
about the
general
distribution
of water
?
28 WATER
EXPERIMENT 13
The Solvent Power of Water
Note to teacher: To avoid repeated weighings small measures may be
made out of glass tubing (not too small inside diameter) sealed at one end.
Weigh out the required amount of the substance. Jar it into the closed end
of the tube and cut off the portion filled with the substance. Place about this
a strong gummed label bringing the ends together for a handle.
Materials. Bottles of soda water (one bottle for each four stu-
dents), alcohol, kerosene, carbon disulfide, powdered copper
sulfate, sodium thiosulfate.
Apparatus. Beaker screen, test tubes, thermometer.
A. Solubility of Gases.
Note : Four students may use one bottle of soda water.
1. Remove the cap from a bottle of soda water. What
causes the bubbling or the effervescence? How is the
pressure on the liquid in the bottle changed when the cap is
removed from the bottle ? How does change of pressure
affect the solubility of a gas ?
2. Pour one fourth of a bottle of soda water into your
beaker (each student alone). Set this on a wire screen on
the ring stand and warm with the burner. Do not heat to
a boiling point of water. Why? How does the rise in
temperature affect the solubility of a gas?
Throw away the soda water and half fill the beaker
with cold water from the faucet and warm it over the burner.
Explain the appearance of small bubbles on the inside of the
beaker.
If a glass of ice water is allowed to stand, bubbles appear
clinging to the inside of the glass. Give your explanation
of this phenomenon.
THE SOLVENT POWER OF WATER 29
B. Solubility of Liquids. {No flames.)
1. Half fill a test tube with water. Add 5 cc. of alcohol.
Shake and look for layers. If a liquid does not dissolve in
water, it will form a layer above it if it is lighter than water,
or below it if it is heavier than water. Does alcohol dissolve
in water?
2. Repeat (1), using kerosene. Will it dissolve? Is it
lighter or heavier than water?
3. Repeat (1), using carbon disulfide. Will it dissolve?
Is it lighter or heavier than water?
C. Solubility of Solids. (Instructor's Experiment.)
1. Put exactly 50 cc. of water in a beaker and add 1-gram
portions of powdered copper sulfate as long as it will dissolve ;
that is, as long as the solution is unsaturated. Stir con-
stantly to aid solution. When no more will dissolve, the solu-
tion is saturated: Note the temperature. How much copper
sulfate will dissolve in a cubic centimeter of water at this
temperature? This is the solubility of copper sulfate for
that temperature.
2. Heat the saturated solution of copper sulfate over a
Bunsen burner flame and add powdered copper sulfate again
in 1-gram portions until no more will dissolve. Note the
temperature. What is the solubility of copper sulfate at
this temperature? How does the rise in temperature affect
the solubility of copper sulfate ?
3. Cool the solution by allowing cold water to flow over
the beaker. • Explain.
4. Repeat the experiment, using some other salt in place
of copper sulfate. Does the rise in temperature increase the
solubility of all substances alike ?
30 WATER
5. Heat fifty or sixty grams of sodium thiosulfate crystals
in a large test tube until they dissolve in the water they con-
tain, forming a saturated solution. Without shaking the tube
cool it in running water. Then the solution is supersaturated
at this temperature, yet no crystals of sodium thiosulfate
appear. Now add a crystal of the salt and note the sudden
formation of crystals and the rise in temperature.1
6. Given a solution of salt how would you prove that it
was unsaturated, saturated, or supersaturated?
EXPERIMENT 14
Boiling Point and Freezing Point of Water
Thermometers
Materials. Ice, salt.
Apparatus. Two-hole rubber stopper, short glass elbow, centi-
grade and Fahrenheit thermometers, flask and screen, test
tube, beakers.
A. Boiling Point of Water.
1. Fit the two-hole rubber stopper with a centigrade
thermometer and a short glass elbow.
Note: Wet the thermometer and tube before inserting and twist them into
place — do not try to push it in or you may break your thermometer and cut
your hand. Insert the stopper in a flask containing about ioo cc. of pure water.
If the thermometer is not immersed in the water, remove the stopper and push
the thermometer further through until it is immersed when the stopper is re-
placed.
2. Clamp the flask carefully on the ring stand over the
ring and wire screen. Heat the water till it boils and note
1 This principle is made use of in certain " waterless hot water
bottles " on the market. These bottles are metal and filled with
sodium thiosulfate crystals. If put into boiling water for ten minutes,
the crystals dissolve. The bottle will then remain hot for some hours
BOILING POINT AND FREEZING POINT OF WATER 31
the temperature when it becomes constant. Apply more
heat by turning up the flame. Does the temperature change ?
Explain.
3. What is the boiling point of water on the centigrade
scale ?
4. Now raise the thermometer out of the water so that
it will be in the steam only as the water boils. Boil the water
and note the temperature of steam. Explain.
5. Obtain a Fahrenheit thermometer and repeat the experi-
ment. What is the boiling point of water on this scale ?
6. Replace the centigrade thermometer in the stopper.
Add ten grams of table salt to the water. Shake until it
dissolves. Note the boiling point. How does salt dissolved
in water affect its boiling point ?
B. Freezing Point of Water.
1. Put some pieces of ice in your 150 cc. beaker and add
about 25 cc. of water. Carefully stir the mixture with the
centigrade thermometer until the temperature is constant.
What is the melting point of ice, centigrade scale?
2. Repeat, using a Fahrenheit thermometer. What is
the melting point of ice, Fahrenheit scale?
3. Make a freezing mixture in your 250 cc. beaker
by mixing three parts of cracked ice with one part of
common salt. Why is the temperature of such a mixture
below the freezing point of water ?
Half fill a test tube with pure water and place the tube in
or as long as a real hot water bottle would remain hot, for it cools down
slowly from 100° C.to room temperature. The solution is then super-
saturated, and if the stopper of the bottle is removed and a wire thrust
into the liquid, crystals will form and heat will be given off for several
hours longer.
32 WATER
the freezing mixture. Note the temperature, centigrade
scale, at which the water begins to freeze. How does the
freezing point of water compare with the melting point of ice ?
C. Problems in Temperature.
1. Note the room temperature on the centigrade ther-
mometer.
From the formula F. = fC.+32 (see Appendix) calculate
the temperature of the room on the Fahrenheit scale. Now
read the Fahrenheit thermometer hanging in the room.
2. On a very warm day the temperature may be 98° F.
What would this be on the centigrade scale ? Use the formula
C. = |(F.-32). (See Appendix.)
3. The normal temperature of the human body is 98° F.
In fever cases the temperature may run up to 106° F. What
would these temperatures be on a centigrade thermometer?
4. The hottest part of the Bunsen flame is 860° C. What
would this temperature be on the Fahrenheit scale ?
5. Alcohol boils at 78° C. and solidifies (freezes) at —130°
C. What would these temperatures be on the absolute
scale? (See Appendix.)
EXPERIMENT 15
How to Purify Water
Materials. Distilled water, salt, bone black, dirt, potassium
permanganate solution.
Apparatus. Watch glass, screen, funnel, filter paper, one round-
bottomed distilling flask, a Florence flask, condenser.
A. How to Show the Presence of Salts Dissolved in Water.
1. Put a few drops of distilled water on your watch glass.
Place this on the wire screen and slowly evaporate it by
HOW TO PURIFY WATER 33
moving the flame back and forth below it. Is there a
residue ?
2. Now place a few drops of faucet water on the glass and
evaporate. A residue indicates something dissolved in the
water. Does the city water contain dissolved salts?
3. What other impurities besides dissolved salts may a
water contain ?
B. Impurities Removed by Filtration.
1. To some water add dirt, some table salt, and some
potassium permanganate to give it color. Place a filter in a
funnel and into this pour a thin paste of bone black and
water. When this has settled, pour on to it some of the tur-
bid, salty, colored water. Is the turbidity removed ? Is the
color removed ? Is the salt removed ? Test this by evapo-
rating a few drops on a watch crystal as before. Would
dangerous germs or poisonous organic matter be removed?
2. What impurities are removed by filtration?
C. Impurities Removed by Distillation. (Instructor's Experiment.)
1. Place about 100 cc. of the same turbid water in a round-
bottomed distilling flask and connect the flask to the con-
denser. Why should the water enter the lower opening of
the condenser jacket? The water flows out of the upper
opening through a rubber tube to the sink. Heat the flask
over a screen until the water boils. The steam from the
boiling water is condensed in the cool condenser tube and
collected in a flask. The condensed liquid is called the distil-
late. The process is distillation.
2. Note the color and taste of the distilled water. Test
for salt by means of the watch glass as before.
3. Where is the salt and coloring matter? What impuri-
34 WATER
ties may be removed by distillation? What impurities may
not be removed in this way ?
4. Which is the better water to drink, filtered water or
distilled water ? Give all the reasons that you can for your
answer.
5. What is the source of the drinking water in your city?
What impurities are present in this water ? What attempts,
if any, are made by the city to remove them ? How could
you make the water more fit for drinking purposes at home?
EXPERIMENT 16
Properties of Hydrogen Peroxide
Materials. Hydrogen peroxide, litmus paper, manganese di-
oxide, dark hair, ammonium hydroxide.
Apparatus. Large test tube, splint, filter paper funnel.
A. Properties of Hydrogen Peroxide.
1 . What is the formula of hydrogen peroxide ? How does
it differ in composition from water?
2. What is the hydrogen dioxide sold by druggists?
3. Place 5 cc. of hydrogen peroxide in a large test tube.
Test with a small piece of litmus paper. Explain.
4. Add 2 grams of powdered manganese dioxide. Thrust a
glowing splint into the tube. What gas is given off? Write
the equation. Filter the mixture remaining in the tube.
What is the residue ? What was the purpose of the manga-
nese dioxide ?
5. Why should bottles of hydrogen peroxide be kept tightly
stoppered? Why are the bottles always dark in color?
6. Why are the corks of the hydrogen peroxide bottles so
white?
PREPARATION AND PROPERTIES OF NITROGEN 35
B. Uses of Hydrogen Peroxide.
1. Wash some dark hairs free from oil, then immerse them
for one hour in 10 cc. of hydrogen peroxide made alkaline
with ammonium hydroxide. Remove them and allow them
to dry. Result ? Hydrogen peroxide is used to bleach wool
and silk.
2. Give some of its uses as a disinfectant.
IV. NITROGEN AND THE AIR
EXPERIMENT 17
Preparation and Properties of Nitrogen
Materials. Phosphorus, charcoal, pine splints, 4 g. ammonium
chloride, and 8 g. -sodium nitrite mixed.
Apparatus. Wide-mouthed bottle, cover glasses, glass pneumatic
trough, 250 cc. flask, one-hole stopper, delivery tube, troughs,
2 gas bottles, ring stand, gauze.
A. Nitrogen from the Air. (Instructor's Experiment.)
Nitrogen and oxygen are the chief gases of the air. If
phosphorus is burned in a bottle of air, it will combine with
the oxygen, forming phosphorus pentoxide. If there is water
in the bottle, the phosphorus pentoxide will dissolve in the
water and nitrogen will be left in the bottle.
1. Pin a piece of phosphorus about the size of a pea to a
piece of charcoal. Float the charcoal on the water in the
glass trough. Light the phosphorus and quickly cover it
with a large, wide-mouthed bottle. Keep the neck of the
bottle pressed well down into the water. With what was the
bottle filled when it was placed over the burning phos-
phorus? What is the "smoke" that is formed as the
36 NITROGEN AND THE AIR
phosphorus burns? What constituent of the air is being
removed ?
2. Allow the bottle tc stand till the " smoke" has dissolved
in the water and the gas in the bottle is clear, then make the
water level the same inside as outside the bottle. Why has
the water risen in the bottle? The gas remaining is chiefly
nitrogen. About what part of the air is nitrogen?
3. Cover the mouth of the bottle with a glass plate and
invert, taking care not to lose any of the water that has risen
in the jar. What are the physical properties of nitrogen in
the jar? What are the physical properties of the nitrogen
in the air? Is the nitrogen in the bottle pure? Why?
4. Thrust the burning splint into the bottle of nitrogen.
Result? Repeat, using phosphorus. Result? Does it
burn ? Does nitrogen support combustion ?
B. Preparation of Pure Nitrogen. Note : Instructor's Experiment,
unless Class Is Very Small.
1. Obtain a mixture of 4 grams of ammonium chloride
and 8 grams of sodium nitrite. Place this in a 250 cc. flask
and add 25 cc. of water. Fit a one-hole rubber stopper and
a delivery tube to the flask in order that the gas may be col-
lected over water as in case of oxygen. Clamp the flask to
the ring stand over a wire gauze and heat very gently by
moving the burner about with the hand. As soon as action
begins, stop heating. If the action becomes too violent, lower
the wire gauze and raise a bowl of water until the flask is
immersed in it and cooled.
When the air is expelled from the flask (about one minute),
fill two gas bottles with nitrogen.
2. The reaction that takes place in the preparation of
pure nitrogen may be expressed in two equations. (1) The
THE COMPOSITION OF THE AIR 37
ammonium chloride and the sodium nitrite react to form
ammonium nitrite and sodium chloride :
NH4Cl+NaN02 — ^ NH4N02+NaCl
(2) The ammonium nitrite then decomposes into water
and nitrogen :
NH4N02 — »- 2 H2O+N2
Write these two equations for the preparation of nitrogen,
naming all substances used and formed.
3. Using one bottle of the gas, note its physical properties,
i.e. its color, odor, taste.
Is it soluble in water ?
Is it heavier or lighter than air ? (See Appendix.)
4. Into the other bottle of gas thrust a burning splint.
Does nitrogen burn ?
Does nitrogen support combustion ?
EXPERIMENT 18
The Composition of the Air
Materials. Phosphorus, splint, limewater, calcium chloride.
Apparatus. Glass trough, graduated tube 100 cc. or 250 cc.,
wire, cover glasses, beaker, long glass elbow, test tube, gas
bottle.
A. The Per Cent of Nitrogen and Oxygen in the Air. (Instructor's
Experiment.)
1. Half fill a glass trough or battery jar with water.
Invert into the jar a graduated tube (about 100 cc or 250 cc).
Adjust so that the water within and without the tube stands
at the same level. Why ? Note the volume of air in the tube.
2. Place a piece of phosphorus on the tip of a wire and
insert in the tube. Push up the wire till the phosphorus
38 NITROGEN AND THE AIR
is in the upper part of the tube. Be careful not to lift the
mouth of the tube from the water.
What are the white fumes that come from the phosphorus ?
What causes the fumes? What gas is being used up?
3. Allow the apparatus to stand until the next day. Note
the position of the water. Why has it risen in the tube?
Are white fumes rising from the phosphorus now? Why?
What is the gas that remains in the tube ?
4. Lower the tube until the water within and the water
without the tube stands at the same level. Why? Note
the volume of the gas in the tube.
5. Slip a cover glass over the mouth of the tube and re-
move it from the jar. To further test the remaining gas
thrust into the tube a blazing splint. Does the gas burn?
Does it support combustion ? What is the gas ?
6. Record your observations and calculate the per cent of
nitrogen in the air, as follows :
(a) Volume of air at the beginning of experiment = cc.
(6) Volume of nitrogen at the end of the experiment = cc.
(c) Volume of oxygen removed by the phosphorus = cc.
Volume of oxygen (c)
= volume of air (a) — volume of nitrogen (6).
The per cent of nitrogen by volume in the air is found as
follows :
Volume of nitrogen (6) X 100 _ .,
A7 , ! . ' — -- % nitrogen
Volume ot air (a)
The per cent of oxygen by volume in the air is found in like
manner :
Volume of oxvgen (c)XlOO _
Volume ot air (a)
THE COMPOSITION OF THE AIR 39
B. Carbon Dioxide in the Air. (Student's Experiment.)
1. Place about 5 cc. of limewater in a clean beaker and
leave it exposed to the air until the close of the laboratory
period. Note the white crust formed on the surface of the
limewater. This proves the presence of carbon dioxide in
the air.
2. Through the long glass elbow blow air from the lungs
into 5 cc. of limewater in a test tube. Explain results. This
is one source of carbon dioxide in the air.
3. Place a burning splint in a bottle of air. In a short
time the splint will go out. Why? Remove the splint and
quickly cover the bottle with a glass plate. Add 5 cc. of
limewater and shake. Results? How does this experi-
ment show another source of carbon dioxide in the air?
4. Name three other sources of carbon dioxide in the
air.
5. If animals are constantly exhaling carbon dioxide, why
does not the per cent of oxygen greatly decrease and the
per cent of carbon dioxide increase as time goes on ?
C. Water Vapor in the Air.
1. Place a piece of calcium chloride on a watch glass or
in a dry beaker and leave it exposed to the air overnight.
(Lock it in your drawer.) In twenty-four hours look at it
again. Explain. A substance that will take up water
from the air in this way is a deliquescent substance. Such
substances are good drying agents.
2. In what other way could you prove the presence of
water vapor in the air ?
3. What are some of the sources of water vapor in
the air ?
40 NITROGEN AND THE AIR
EXPERIMENT 19
Ammonia, NH3
Materials. Ammonium chloride (10-g. portions), slaked lime
(20-g. portions), concentrated hydrochloric acid, red litmus solu-
tion, splints, red litmus paper, and blue litmus paper.
Apparatus. Large test tube, one-hole rubber stopper, long el-
bow, 4 gas bottles dry, 2500-cc. beaker, cover glasses.
A. Preparation of Ammonia.
1. Obtain 10 grams of ammonium chloride and 20 grams of
calcium hydroxide (slaked lime). Smell of each. Has
either an odor ? Now mix them well on a paper with a stir-
ring rod and smell again. What is the odor? Put the
mixture in the large test tube. Insert the one-hole stopper
with the long elbow. Clamp the test tube in the ring stand,
with the outlet tube turned up. Heat the test tube gently.
Collect three bottles of the gas by inverting the bottle over
the tube and holding it there until a drop of hydrochloric
acid held on a stirring rod at the mouth of the bottle fumes
strongly. Is ammonia heavier or lighter than air? Write
the word-and-symbol equation for the reaction that takes
place in the preparation of ammonia.
2. Turn the outlet tube down and insert it into a bottle
containing about 20 cc. of water. The tube must not touch the
ivater. Why? Heat the mixture until no more gas is given
off. (While heating, test the properties of the gas collected.)
B. Properties of Ammonia.
1. What is the color and odor of ammonia?
2. Moisten your finger and hold it in the gas. Touch it
to the tongue. What is the taste of ammonia ?
GENERAL PROPERTIES OF ACIDS, BASES, AND SALTS 41
3. Fill your large beaker with water and color it with a
few drops of red litmus solution. Uncover a bottle of am-
monia and quickly thrust its mouth into the water. Hold
it in this position for five minutes. Result? Why not
collect ammonia over water?
4. Put a few drops of hydrochloric acid in a bottle ; cover
and shake well. Place it mouth downward over a bottle
of ammonia and remove the glass covers. Result? Explain
and write the equation.
5. Thrust a lighted splint into a bottle of ammonia.
Does it burn or support combustion ?
6. Remove the outlet tube from the bottle containing the
liquid. Smell the liquid. Test it with red and with blue
litmus. The gas ammonia combined with the water to
form ammonium hydroxide.
NH3+H20 — > NH4OH
For what purpose is this liquid used in the home? It is
commonly called "ammonia." Is this correct? Explain.
V. ACIDS, BASES, AND SALTS
EXPERIMENT 20
General Properties of Acids, Bases, and Salts
Materials. Sulfuric acid, hydrochloric acid, nitric acid, acetic
acid, crystals of tartaric acid, red litmus paper, blue litmus
paper, magnesium ribbon pieces 1 cm. long, sodium hydroxide,
potassium hydroxide, ammonium hydroxide, calcium hydroxide
solution (limewater), sodium chloride, potassium sulfate, am-
monium chloride, sodium carbonate, phenolphthalein, methyl
orange.
Apparatus. Test tubes, stirring rod, splints.
42 ACIDS, BASES, AND SALTS
A. General Properties of Acids.
1. Half fill five clean test tubes with water. To the first
add 3 drops of concentrated sulfuric acid, H2SO4; to the
second add 3 drops of hydrochloric acid, HC1 ; to the third
add 3 drops of nitric acid, HNO3 ; to the fourth add 3 drops
of acetic acid, HC2H3O2 ; in the fifth dissolve a crystal of
tartaric acid, H2C4H406.
2. Dip the clean stirring rod into the dilute sulfuric acid
and carefully taste a drop of it. Rinse the mouth with
water after tasting. Wash the rod and dip it into the dilute
solution of hydrochloric acid and taste a drop of it. Repeat,
using nitric, acetic, and tartaric acids. What is the charac-
teristic taste of acids ?
3. In each tube place a very small piece of red and of blue
litmus paper. What effect have acids on litmus? Empty
the tubes and prepare solutions of the acids as in (1). To
each tube add a drop of methyl orange. Note result in each
case.
Note: Litmus and methyl orange are called indicators because by their
characteristic color reactions they indicate the presence of acids. By giving
a different color they may also be used to indicate the presence of bases, as
will be shown later.
4. Place about 10 cc. of each acid in separate clean test
tubes and add to each (one at a time) a piece of magnesium
ribbon about 2 cm. long. Cover the tube with the hand, or a
piece of cardboard, for about a minute or until effervescence
ceases ; then test the gas in the tube with a burning splint.
What is the gas? WThere does it come from? Write the
word-and-symbol equations for the reactions that take place
in each case. Do acids dissolve other metals?
5. Write in a vertical column, one under the other, the
names and formulas of the five acids you have studied.
GENERAL PROPERTIES OF ACIDS, BASES, AND SALTS 43
Compare the formulas. In what respect are the acids
similar in composition ?
6. Define an acid as completely as you can.
7. What are the chief acids formed in vinegar ? lemon
juice ? sour milk ? (See textbook.)
B. General Properties of Bases.
Note to student: An hydroxide (sometimes called hydrate) is composed
of a metal or metallic radical combined with one or more hydroxyl radicals.
Most of the hydroxides are insoluble. A few are soluble ; these are called
bases and they possess properties in common, as will be noted below.
1. In four different test tubes obtain 10 cc. of sodium
hydroxide, NaOH, potassium hydroxide, KOH, ammonium
hydroxide, NH4OH, and calcium hydroxide, Ca(OH)2, re-
spectively. Label the tubes.
2. Taste the calcium hydroxide. Do not taste the others
without diluting greatly — about one drop in a half test tube
of water. Describe the taste of the bases.
3. Drop a small piece of pink and of blue litmus in each
tube. Results? Test fresh solutions of each with a drop
of methyl orange. Result in each case? Test fresh solu-
tions of each wTith a drop of phenolphthalein. Result in
each case ?
4. Rub a little of each solution between the fingers.
Describe the feeling.
5. Write in a vertical column, one under the other, the
names and formulas of the four bases you have studied.
Compare the formulas. In what respect are the bases similar
in composition ?
6. Define a base as completely as you can.
7. What is the chief hydroxide in "limewater" ? "house-
hold ammonia" ? "Red Seal lye" ?
44 ACIDS, BASES, AND SALTS
C. General Properties of Salts.
1. In separate test tubes obtain about one gram of sodium
chloride, NaCl, potassium sulfate, K2SO4, ammonium chlo-
ride, NH4CI, and sodium carbonate, Na2C03. Label the tubes.
2. Half fill the tubes with water ; shake and warm until
the salts dissolve. Taste each solution. Do they taste like
acids or bases ? Rinse your mouth.
3. Place in each tube a piece of red and of blue litmus
paper.
What effect have salts such as sodium chloride and potas-
sium sulfate upon litmus?
Explain briefly why solutions of salts such as ammonium
chloride turn litmus red. (See hydrolysis in text.) Why
do solutions of salts like sodium carbonate turn litmus blue ?
4. Rub a solution of each salt between the fingers. Do
they feel slippery ?
5. Write the names and formulas of the salts in a vertical
column, one under the other. Compare the formulas.
6. Define a salt as completely as you can.
7. What is ordinary "table salt"? "baking soda"?
"washing soda"? "saltpeter"?
D. Litmus Reaction of Common Substances.
* Note : These tests are to be made at home.
1. Take home five or six strips of red and of blue litmus
paper and test the following substances with a portion of
each strip. Dissolve solids in water before testing. Tabu-
late the reaction toward litmus under the following heads :
Acid Reaction Basic Reaction Neutral Reaction
Test: Borax, soap, faucet water, tooth powder, pickle, cream of tartar,
washing soda, sour milk, sweet milk, vinegar, lemon juice, ripe fruits, green
fruits, sugar, and olive oil.
METHODS OF FORMING ACIDS, HYDROXIDES, AND SALTS 45
EXPERIMENT 21
Methods of Forming Acids, Hydroxides, and Salts
Note: Two double laboratory periods will probably be required for this
experiment.
Materials. Sodium, filter paper, solution of phenolphthalein,
lime, copper sulfate, ferric chloride and magnesium chloride
(solution), sodium hydroxide, hydrochloric acid, magnesium
ribbon, red phosphorus, sulfur, sodium chloride.
Apparatus. Evaporating dish, glass plate, red litmus paper, blue
litmus paper, small beaker, funnel, asbestos paper.
A. Methods of Forming Acids.
1. Action of non-metallic oxides on water.
Note: A non-metallic oxide which when dissolved in water will produce
an acid is called an acid anhydrid.
(a) In the combustion spoon place a small piece of asbestos
paper and on it a little sulfur. Ignite the sulfur in the
Bunsen flame and lower the spoon into a bottle of air, cover-
ing the bottle as far as possible with a glass plate. When
the action ceases, remove the spoon. What is in the bottle ?
Write the word-and-symbol equation for the reaction.
Now add about 5 cc. of water and shake thoroughly.
Test the liquid with both red and blue litmus. Result?
What acid has been formed ? Write the word-and-symbol
equation.
(b) Reline the spoon with asbestos and repeat (a) , using
a small amount of red phosphorus (about the size of a ker-
nel of wheat). What is the oxide formed? Write the
word-and-symbol equation. Add water; shake and test
with litmus. Result? What is the acid formed? Write
the word-and-symbol equation.
46 ACIDS, BASES, AND SALTS
(c) When carbon dioxide is dissolved in water, carbonic
acid is formed. Write the word-and-symbol equation to
show the reaction.
(d) What oxide is the anhydrid of sulfuric acid? Write
the word-and-symbol equation.
2. Action of an acid with a higher boiling point on the
salt of the acid desired.
Note : Sulfuric acid has a much higher boiling point than the common acids,
such as hydrochloric, nitric, and acetic acids, so that it is generally used in the
preparation of these acids on a large scale.
(a) Place about 5 grains of sodium chloride in a test tube
and add 5 cc. of concentrated sulfuric acid. Warm gently
and cautiously. Note the odor of the gas evolved. Test the
gas with strips of red and of blue litmus moistened. Result ?
This gas is hydrogen chloride or hydrochloric acid gas.
Write the word-and-symbol equation for the reaction.
Note: This method will be given in detail later. See Experiment 22.
(6) Write the word-and-symbol equation for the reaction
between sodium nitrate and sulfuric acid to form nitric acid.
B. Methods of Forming Hydroxides.
1. Action of metallic oxides on water.
Note : A metallic oxide which when dissolved in water will produce a base
is called a base anhydrid.
(a) What is lime ? How is it formed ?
(b) Obtain about 5 grams of lime. Place it in your
small beaker and add 10 cc. of water. Stir for about 5 min-
utes, then filter. What is the residue on the filter paper?
What is in the filtrate ? Write a word-and-symbol equation
to show what is formed when calcium oxide is added to water.
Rub some of the solution between the fingers. Taste it.
METHODS OF FORMING ACIDS, HYDROXIDES, AND SALTS 47
Test it with litmus and phenolphthalein. Note results in
each case. Write the word-and-symbol equation for the
reaction. Is calcium hydroxide as soluble as sodium hy-
droxide ?
2. Action of metals on water. (Instructor's Experiment.)
(a) Place on a piece of filter paper a piece of sodium about
as large as a pea. Half fill your evaporation dish with
water. Have a glass plate ready to cover it. Drop the
sodium on the water and cover the dish with the glass plate.
Note what takes place. (Recall Experiment 10.)
When the action is over, rub some of the solution between
the fingers. Result? Taste it carefully. Result? Test
with pieces of red and of blue litmus. Result? Add a drop
of phenolphthalein solution. Result?
What substance is contained in the water ?
Write a word-and-symbol equation to show its formation
from the sodium and water.
(b) Potassium hydroxide could be prepared in the same
way, using potassium instead of sodium. Write the word-
and-symbol equation to show what would take place.
Are potassium and sodium hydroxides soluble or insoluble ?
3. Insoluble hydroxides.
In three separate test tubes obtain 5 cc. of solutions of
the salts, copper sulfate, ferric chloride, and magnesium
chloride. Fill each test tube half full of water and add 1 cc.
of sodium hydroxide to each tube. What is formed in each
case? Write the word-and-symbol equation to show what
was formed in each case.
Insoluble hydroxides do not feel slippery. They have no
taste. They do not affect litmus. They do react with
acids to form salts as soluble hydroxides do.
48 ACIDS, BASES, AND SALTS
C. Methods of Forming Salts.
1. By neutralization — the action of an acid on a base.
Place 10 cc. of sodium hydroxide, NaOH, in a beaker and
add a drop of phenolphthalein. Then add hydrochloric
acid, HC1, till the color just disappears. Rub some of the
solution between the fingers. Taste it. Test it also with
red and with blue litmus. Is an acid present? Is a base
present? What has been formed? Evaporate 10 cc. of
the solution to dryness in the evaporation dish. Taste the
solid. Why is this process called neutralization? Write
the word-and-symbol equation.
2. By the action of acids on metals.
Recall the action of sulfuric acid, H2S04, on zinc in the
preparation of hydrogen in Experiment 9. Write the word-
and-symbol equation for the reaction.
Add some hydrochloric acid, HC1, to about an inch of
magnesium ribbon in a test tube. What gas is liberated?
When the action ceases, evaporate some of the liquid to dry-
ness. What salt was formed? Write the word-and-symbol
equation for the reaction.
Note: The instructor may perform the following experiments or merely
discuss them in class.
3. By the action between elements.
When iron is heated with sulfur, iron sulfide, FeS, is formed.
Write the word-and-symbol equation.
Also when copper reacts with chlorine, copper chloride,
CuCl2, is formed.
Write the word-and-symbol equation.
When zinc dust (2 parts) and sulfur (1 part) are mixed and
heated, zinc sulfide, ZnS, is formed.
4. By the action of acids on oxides.
SOLUTIONS THAT CONDUCT THE ELECTRIC CURRENT 49
Magnesium oxide, MgO, reacts with hydrochloric acid, HC1,
to form magnesium chloride, MgCl2, and water.
Write the word-and-symbol equation.
5. From another salt when a gas is formed.
The salt potassium chlorate, KC103, when heated will
give a new salt, potassium chloride, KG, and oxygen.
Write the word-and-symbol equation.
6. From another salt when an insoluble substance is
formed.
If a solution of the salt barium chloride, BaCl2, is added to
a solution of sodium sulfate, Na2S04, two new salts are formed
— one insoluble salt, barium sulfate, BaSC>4, and one soluble
salt, sodium chloride, NaCl.
Write the word-and-symbol equation.
EXPERIMENT 22
(Class Experiment)
Solutions That Conduct the Electric Current
Materials. An electric lighting current, distilled water, about
half normal solutions of hydrochloric acid and sulfuric acid and
acetic acid, sodium hydroxide, ammonium hydroxide, sodium
chloride, zinc sulfate, sugar, alcohol, concentrated sulfuric acid.
Apparatus. A lamp block with a 16 candle-power lamp, an
electric cell consisting of a tall 10-cc. beaker and 2 platinum
or carbon electrodes.
Note: If the solution of a substance in water will conduct the electric
current, the substance is called an electrolyte.
If it will not conduct a current it is a non-electrolyte.
A. Conducting Power of Pure Water.
1. Connect an electric lighting current in series with a 16
candle-power electric lamp and cell consisting of a small beaker
50 ACIDS, BASES, AND SALTS
and two carbon electrodes. The lamp cuts down the current
strength and indicates the passing of a current by lighting.
2. Pour distilled water into the beaker until the electrodes
are completely immersed. Does the lamp glow? Will
pure water conduct the electric current ?
B. Conducting Power of Concentrated Sulfuric Acid.
1. Immerse perfectly dry electrodes in a cell of concen-
trated sulfuric acid. Does the lamp glow? Will pure
concentrated sulfuric acid conduct the electric current?
C. Conducting Power of Solutions of Acids.
1. Dissolve one drop of sulfuric acid in the distilled water
in the cell. Does the lamp glow? Will a water solution
of sulfuric acid conduct the electric current? Is sulfuric
acid an electrolyte ?
2. Remove and wash the electrodes and replace the solu-
tion of sulfuric acid with a dilute solution of hydrochloric
acid. Result ?
3. Remove and wash the electrodes and replace solution
of hydrochloric acid with a solution of acetic acid. Does the
lamp glow as brightly as in (1) or (2)? Does the acetic
acid conduct the current as well as hydrochloric acid ? The
action of these acids is characteristic of nearly all acids.
Acids in water give ions. The ions carry the current. What
ions does sulfuric acid give? What ions does hydrochloric
acid give? What ions does acetic acid give? What ions
do all acids give? Some substances in solution give more
ions than others. The one that gives the most ions conducts
the current best. The acid that gives the most hydrogen
ions is the strongest acid (the concentrations being the same) .
Which of the three acids above are strong? which weak?
SOLUTIONS THAT CONDUCT THE ELECTRIC CURRENT 51
D. Conducting Power of Solutions of Bases.
1. Replace the acid solution by a solution of sodium hy-
droxide. Result? Is sodium hydroxide an electrolyte?
2. Repeat, using ammonium hydroxide. Does the lamp
glow as brightly as (1) ? Does ammoni m hydroxide con-
duct the current as well as a solution of sodium hydroxide?
What ions does sodium hydroxide give ?
What ions does ammonium hydroxide give ?
What ions are common to all bases?
The base giving most hydroxyl ions is the strongest (the
concentrations being the same in each case) . Which is the
stronger base, sodium hydroxide or ammonium hydroxide ?
E. Conducting Power of Solutions of Salts.
1. Place in the beaker a solution of sodium chloride.
Result? What ions does sodium chloride give in solution?
2. Repeat, using a solution of zinc sulfate. Result?
What ions does zinc sulfate give in solution? In general,
what ions do all the more common salts give in solution ?
F. Conducting Power of Non-electrolytes.
1. Place in the beaker a solution of sugar. Does it con-
duct the electric current ? Why ?
2. Repeat, using a solution of alcohol. Does it conduct
the current ? Why ?
Questions
1 . What electrolytes did you study in this experiment ?
2. What non-electrolytes did you study?
3. Define an acid, a base, and a salt with reference to the
ions they give in solution.
4. Define a strong acid.
5. Define a concentrated acid.
52 THE HALOGENS AND HYDROCHLORIC ACID
VI. THE HALOGENS AND HYDROCHLORIC ACID
EXPERIMENT 23
Chlorine, Bromine, and Iodine
Materials. Bleaching powder (fresh), 4 7V sulfuric acid, strips
of colored calico, white cloth, colored flowers, potassium iodide,
potassium bromide, starch paste, and alcohol.
Apparatus. 500-cc. Florence flask, stopper, thistle tube, de-
livery tubes, gas bottles, 250-cc. Florence flask, test tubes, and
beaker.
Caution: Chlorine is poisonous. The instructor usually performs the
experiment.
A. Preparation of Chlorine.
1. Place 50 grams of bleaching powder (chlorinated lime)
in a 500 cc. Florence flask. To the flask fit a stopper
containing a thistle tube and a delivery tube. The delivery
tube should extend to the bottom of a dry bottle covered
with cardboard. The gas is heavier than air and may be
collected by displacement of air.
Through the thistle tube add about 50 cc. of 4 N sulfuric
acid. If necessary, warm the flask gently. Collect four
bottles of the gas and cover them with glass plates. Com-
plete the equation, naming the substances :
CaOCl2+H2S04^
B. Properties of Chlorine.
1. Extend the delivery tube into the bottle half filled
with water. Does chlorine dissolve in water ?
2. Note the color of chlorine gas, and very carefully note
its odor by wafting to the nose by the hand.
3. In another bottle suspend a strip of moist calico and
a strip of dry, colored calico. Explain the water's action.
CHLORINE, BROMINE, AND IODINE 53
4. In another bottle place violets or a carnation. Re-
sult?
5. In the fourth bottle suspend a strip of moist white
cloth having an ink stain. Result ?
6. Into the "chlorine water" prepared in (1) place a
strip of white goods having an ink stain.
7. Explain the use of bleaching powder (chlorinated lime)
in removing stains and in bleaching goods, and as a disin-
fectant.
C. Preparation and Properties of Bromine.
1. Place 5 grams of powdered potassium bromide and 3
grams of manganese dioxide in a 250 cc. Florence flask. Add
20 cc. of 4 N sulfuric acid. Warm if necessary. Write the
equation for the preparation.
2. Note the color and the odor of the bromine gas. At
an ordinary temperature bromine is a liquid. It is the
only liquid non-metal. Examine some liquid bromine.
Pour a drop of bromine into water. Does it dissolve ? Is it
heavier or lighter than water ?
D. Preparation and Properties of Iodine.
1. Repeat C, 1 using potassium iodide instead of potas-
sium bromide. Write the equation for the preparation of
iodine.
2. Note the color of iodine vapor. What collects upon
the cold neck of the flask ?
3. Examine crystals of iodine. Describe them. Put a
crystal in a test tube and heat it. Result? What collects
on the sides of the tube? Explain.
4. Try to dissolve a crystal of iodine in water. Result?
Pour off the water and add alcohol. The solution of iodine
54 THE HALOGENS AND HYDROCHLORIC ACID
in alcohol is called "tincture of iodine." What is this used
for?
5. To a beaker of water add 1 drop of starch paste and then
1 drop of the tincture of iodine prepared in (4). Result?
This is a test for starch.
EXPERIMENT 24
Preparation and Properties of Hydrochloric Acid, HC1
Materials. 30 g. portions of NaCl, 4 N sulfuric acid, litmus
paper, splints, blue litmus solution, silver nitrate solution, am-
monium hydroxide, nitric acid, potassium chloride.
Apparatus. 250 cc. Florence flask, delivery tubes, gas bottles,
large beaker, test tubes, thistle tube.
A. Preparation of the Gas Hydrogen Chloride.
1. Put about 30 grams of sodium chloride (common salt)
into your 250 cc. Florence flask. Insert the 2-hole rubber
stopper containing the thistle tube and delivery tube. At-
tach the long delivery tube to the short one and extend it
into a dry gas bottle covered with cardboard. Add through
the thistle tube about 50 cc. of sulfuric acid and warm
gently. Collect 2 bottles of gas hydrogen chloride. The
bottles are full when a piece of moist blue litmus paper held
at the mouth turns pink. Cover them with about 50 cc.
of water, forming hydrochloric acid. Write the word-and-
symbol equation for the preparation of the gas hydrogen
chloride.
B. Properties of the Gas Hydrogen Chloride.
1. Note the color and odor of the gas. Is it heavier than
air?
SULFUR AND COMPOUNDS OF SULFUR 55
2. Thrust a lighted splint into one of the bottles. Does
hydrogen chloride burn ? Does it support combustion ?
3. Fill your large beaker with water and add 1 cc. of blue
litmus solution. Uncover the second bottle of the gas and
invert it quickly in the beaker of water. Explain the result.
C. Properties of Hydrochloric Acid.
1. Remove the delivery tube from the bottle containing
the water in which the hydrogen chloride has dissolved,
forming hydrochloric acid. Test the liquid with blue litmus
paper. Result? Taste a drop of the liquid. Result?
What is the hydrochloric acid on your desk ?
2. Place 5 cc. of the hydrochloric acid which you prepared
in a test tube and add a drop of silver nitrate. What is the
white precipitate formed ? Write the word-and-symbol equa-
tion. Divide the precipitate into two parts. To one part
add ammonium hydroxide till the liquid is alkaline. Result ?
To the other part add nitric acid. Result ?
3. Repeat (2), using any soluble chloride instead of hy-
drochloric acid. Result? Write the equation to show the
formation of silver chloride.
State the test for hydrochloric acid and its salts. What
is the general method for the preparation of an acid?
VII. SULFUR AND COMPOUNDS OF SULFUR
EXPERIMENT 25
Sulfur and Compounds of Sulfur
Materials. Sulfur, colored goods, a colored flower, sodium
sulfite, concentrated sulfuric acid.
Apparatus. Deflagrating spoons, gas bottle, pneumatic trough,
litmus paper, flask, test tubes, safety tube, delivery tube.
56 SULFUR AND COMPOUNDS OF SULFUR
A. Sulfur.
1. Note the physical properties of sulfur, i.e. color, odor,
taste.
2. Boil some sulfur in a test tube half full of water. Filter
and note that the water is pale yellow. Is sulfur soluble
in water?
3. What are some of the uses of sulfur?
B. Sulfur Dioxide, S02.
1. Place about 20 grams of sodium sulfite in a flask. In-
sert the stopper with a thistle tube and delivery tube. Add
concentrated sulfuric acid through the thistle tube. Warm
the flask if necessary. Collect the gas by downward dis-
placement of air. Fill 3 bottles. Write the equation to
show the reaction that takes place in this method of prepar-
ing sulfur dioxide.
Note: Sulfur dioxide can also be prepared by burning sulfur in the air.
Write the equation.
2. Note the physical properties of the gas, i.e. the color
and odor. Half fill your trough with water and quickly
invert one bottle of sulfur dioxide in it. Is sulfur dioxide
soluble in water? When the water no longer rises slip a
glass plate over the mouth of the bottle and place it right
side up on the table. Taste the liquid in the bottle. Test
it with red and with blue litmus. What is formed when sulfur
dioxide dissolves in water ? Write the equation to show the
reaction.
3. Into the second bottle thrust a burning splint. Does
sulfur dioxide burn or support combustion ?
4. Into the third bottle of sulfur dioxide place a strip of
moistened colored goods and also a fresh violet or carnation
SULFURIC ACID AND HYDROGEN SULFIDE 57
or other colored flower. This illustrates the use of sulfur
dioxide as a bleaching agent for nuts and fruits before they
are dried. In this case the sulfur dioxide is prepared by
burning sulfur in air.
EXPERIMENT 26
Sulfuric Acid and Hydrogen Sulfide
Materials. Pine splint, concentrated sulfuric acid, sugar, sodium
acetate, distilled water, barium chloride solution, hydrochloric
acid, and ferrous sulfide.
Apparatus. Test tubes, flask, delivery tube, safety tube, litmus
paper, and splints.
A. Sulfuric Acid.
1. Pour 1 cc. of concentrated sulfuric acid into 5 cc. of
water in a test tube. {Caution: Never pour the water into
the acid.) Note the heat produced by touching the bot-
tom of the test tube to the hand.
2. Thrust a pine splint into 5 cc. of concentrated sulfuric
acid in a test tube. Warm gently. Remove the splint and
note result.
3. To a gram of sugar in another test tube add a few drops
of concentrated sulfuric acid. Warm and explain result.
Write the equation to illustrate in a general way what took
place. Explain why concentrated sulfuric acid causes such
serious burns.
4. Half fill a test tube with distilled water , then add a drop
of concentrated sulfuric acid. To this add 1 cc. of barium
chloride solution. The precipitate is barium sulfate, BaS04.
Try to dissolve the precipitate in hydrochloric acid. Result 9
In nitric acid. Result? State the test in your own
58 SULFUR AND COMPOUNDS OF SULFUR
words. Complete the following equations, naming all sub-
stances :
H2S04+BaCl2 — ^
Na2S04+BaCl2 — ^
B. Hydrogen Sulfide.
1. Set up your flask as a gas generator. In it place 10
grams of ferrous sulfide. Add hydrochloric acid through the
safety tube. Collect a bottle of the gas by downward dis-
placement of air. Complete the following equation for
the reaction, naming all substances :
FeS+2 HC1— ^
2. Note the physical properties of the gas, i.e. color, odor.
Note : Let the gas bubble into a test tube of water while you are studying
the properties of the gas in the bottle.
3. Thrust a burning splint into the bottle of gas collected.
Result?
The hydrogen sulfide is oxidized to water and sulfur
dioxide when it burns. Write the equation for the reaction
which takes place when hydrogen sulfide burns in the air.
2H2S+3 02 — ^
Sometimes sulfur is precipitated if the oxidation is incom-
plete. Write an equation to illustrate this reaction.
2H2S+02->
Hydrogen sulfide is a strong reducing agent.
4. Test the solution of hydrogen sulfide prepared in (2)
with red and with blue litmus. Result? It is a very weak
acid. Put a drop of the solution on a silver coin. Result?
Why do silver spoons turn black if used for eating eggs ?
5. How would you test for a sulfide ?
CARBON 59
VIII. CARBON. CARBON DIOXIDE. FLAMES
EXPERIMENT 27
Carbon
Materials. Potato, bread, meat, starch, sugar, cotton, paper,
wood, coal, any vegetable, sand, wood charcoal, lampblack,
bone black, graphite, coal, sulfuric acid, sodium hydroxide,
brown sugar, copper oxide.
Apparatus. Iron pan, ring stand, test tubes, filter paper, funnel,
beaker, hard-glass test tube.
A. Occurrence of Carbon.
1. Place a thin layer of sand in a small iron pan and on it
put small pieces of the substances listed above. Cover the
materials with sand to protect from the action of the air.
Why? Heat until smoking ceases. Cool and examine.
What has happened to the substances? What is the black
residue ?
How is willow charcoal prepared ? How is animal charcoal
prepared ? For what purposes are these substances used ?
2. Close the holes in the Bunsen burner ; light it and turn
it low. This makes a small luminous flame. Hold a cold,
dry surface or evaporating dish in this flame. Result?
What is this form of carbon called ?
How is lampblack prepared? For what purpose is it
used? What element is found in the foods we eat and the
fuels we burn ?
B. Properties of Carbon.
1. In five different test tubes place respectively about
5 grams of wood charcoal, bone black (animal charcoal),
graphite, lampblack, coal.
60 CARBON. CARBON DIOXIDE. FLAMES
Note the physical properties of each.
Place small portions of each in other test tubes and add
some water. Are any of the forms of carbon soluble in water ?
2. Place portions of each in other tubes and add some
sulfuric acid or any acid. Result ?
Repeat, using sodium hydroxide. Result?
3. Dissolve 20 grams of brown sugar in 100 cc. of water.
Note the color of the solution. Add 10 grams of bone black
and boil for ten minutes. Filter. Note the color of the fil-
trate. Taste it. Where is the sugar? If the filtrate is not
colorless, add some more bone black ; warm and filter again
till it is colorless. How is bone black used in sugar refining ?
4. In a hard-glass test tube heat for 10 minutes a mixture of
3 grams of powdered wood charcoal with 3 grams of copper
oxide. Cool and pour the contents upon a paper. What is
the reddish material ? What becomes of the charcoal ?
Write an equation to show the reducing action of carbon
in this case.
EXPERIMENT 28
Carbon Dioxide, C02
Materials. Marble chips, dilute hydrochloric acid, splints, lime-
water.
Apparatus. Flask, safety tube, stopper, delivery tube, bottles,
beaker, test tubes.
A. Preparation of Carbon Dioxide.
1. Place some pieces of marble in your 250 cc. flask. Insert
the stopper containing the safety tube and the delivery tube.
Add dilute hydrochloric acid through the safety tube, a few
centimeters at a time.
2. Collect three bottles of the gas by downward displace-
CARBON DIOXIDE, C02 61
ment of air. The bottle is full when the flame of a burning
splint held at its mouth is extinguished.
3. Write the equation for the reaction between hydro-
chloric acid and marble in the preparation of carbon
dioxide.
B. Properties of Carbon Dioxide.
1. Note the chief physical properties of carbon dioxide.
Test its solubility in water by inserting one of the bottles of
the gas in a beaker of water. Let it stand. Does the water
rise? Is carbon dioxide soluble in water?
2. Into a second bottle of the gas thrust a burning splint.
Result ? What use does this suggest for the gas ?
3. Prove that the gas is heavier than air by pouring a
bottle of it into an empty bottle as if it were a liquid. Test
for its presence in the second bottle with the burning splint.
Result?
4. Extend the delivery tube from the generator into 10 cc.
of limewater in a test tube and allow the carbon dioxide
to bubble through the limewater. What is the white precipi-
tate obtained? Write the equation for the reaction. This
is a test for carbon dioxide.
5. Prove that air exhaled from the lungs contains carbon
dioxide by blowing some air through 10 cc. of fresh lime-
water in a test tube. Explain the presence of carbon dioxide
in the air exhaled from the lungs.
6. Burn a splint in a bottle. Cover the bottle. Add
limewater and shake. Result? Explain.
7. Burn a piece of paper in a bottle. Cover the bottle.
Add limewater and shake. Result? Explain.
8. Any substance which contains carbon will form carbon
62 CARBON. CARBON DIOXIDE. FLAMES
dioxide when it burns. The limewater test for carbon
dioxide is therefore an indirect test for carbon.
Note: If there is time, perform A, i and B, i of Experiment 29.
EXPERIMENT 29
Carbonic Acid and Carbonates
Materials. Carbon dioxide generator, sodium hydroxide, sodium
bicarbonate, copper carbonate, magnesium carbonate, sodium
bicarbonate, hydrochloric or sulfuric acids, limewater, baking
soda, washing soda, boiler scale, sea shells, limestone.
Apparatus. Evaporating dish, test tubes.
A. Carbonic Acid, H2C03.
1. Pass some of the carbon dioxide gas from the generator
used in Experiment 28 through 25 cc. of water. The gas
combines with the water to form carbonic acid. Write the
equation for the reaction. Taste the liquid. Result ? Test
the acid formed with blue litmus paper. Result?
Now explain what soda water is.
B. Salts of Carbonic Acid, the Carbonates.
1 . Pass carbon dioxide through 20 cc. of solution of sodium
hydroxide in a test tube as long as any gas is absorbed. Pour
the solution into your evaporating dish and evaporate to
dryness. What substance remains? Write the equation
for the reaction.
2. In labeled tubes obtain 1 gram of sodium bicarbonate,
copper carbonate, magnesium carbonate, and sodium carbon-
ate. Note the physical properties of each. Place half of the
sodium bicarbonate in another test tube, add 20 cc. of water,
warm, and shake. Is sodium bicarbonate soluble in water?
In like manner test the solubilitv of the other carbonates
FLAMES 63
you obtained. Make a table showing which of the carbon-
ates tested are soluble in water and which are insoluble.
3. To the other half of the sodium bicarbonate add either
dilute hydrochloric or sulfuric acid. Carbon dioxide gas is
evolved. Prove this by holding a drop of limewater on a
stirring rod in the gas coming from the tube. If the drop
becomes milky, carbon dioxide is indicated.
Write the equation for the reaction.
In like manner test the action of an acid on the other car-
bonates you obtained. Write the equations for the reactions
in each case. All carbonates, when treated with hydro-
chloric or sulfuric acid, evolve carbon dioxide. This is the
test for a carbonate.
4. Test baking soda for a carbonate. What is baking soda ?
5. Test washing soda for a carbonate. What is washing
soda?
6. Test boiler scale from a teakettle at home for a carbon-
ate. What is boiler scale ?
7. Test coral, oyster shell, or any other sea shell for a car-
bonate. Of what are sea shells composed chiefly?
8. Test limestone for a carbonate. What is limestone ?
EXPERIMENT 30
Flames
Materials. Candles, splints, powdered wood charcoal.
Apparatus. Glass elbow or tube, wire screen, evaporating dish.
A. Candle Flame.
1. Place a lighted candle so that the flame is against a
black background and note the different cones in the flame.
Draw a diagram showing the different parts of the flame.
64 CARBON. CARBON DIOXIDE. FLAMES
2. Test the different cones in the flame with a small splint.
Which is the hottest cone ?
3. Blow out the flame and hold a lighted splint in the little
column of smoke coming from the wick. Explain the result.
4. Candle wax is composed chiefly of carbon and hydrogen.
What then are the chief products of combustion when a
candle burns in the air? Prove the presence of these prod-
ucts by very simple experiments.
B. Bunsen Flame.
1. Draw the diagram of a Bunsen flame.
2. Test the different cones in the flame with small splints.
Which is the hottest flame? Hold a splint horizontally in the
base of the Bunsen flame for three seconds. Explain the
result.
3. Put one end of a glass elbow or glass tube in the inner
cone just above the burner tube and light the gas at the end
of the glass tube. Raise the tube until it is in the Bunsen
flame's second cone. Result ? What is the inner cone of the
Bunsen flame?
4. Press the wire screen down in the Bunsen flame. Why
does the flame not burn above the screen? Light the gas
above the screen. Turn the gas off, then turn it on again
and light it above the wire screen held about two inches
above the top of the burner. Explain.
5. Shake some powdered wood charcoal into a non-lumi-
nous Bunsen flame. Explain the result. Beat some of the
chalk dust from a blackboard eraser into a non-luminous
flame. Explain the result.
6. Make the Bunsen flame luminous by closing the holes
in the tube. Hold a clean, dry evaporating dish in the
FLAMES 65
luminous flame. Why is carbon (lampblack) deposited?
Will a non-luminous flame deposit soot? What makes a
flame luminous ?
7. The flame produced by the burner of the kitchen range
is non-luminous. Explain how the burner is constructed to
produce this non-luminous flame. Draw a diagram.
What advantages has a non-luminous flame over a lumi-
nous one in such a range ? How could the same gas that is
used for lighting purposes in the range be used for lighting
the home ?
PART II
SECOND TERM'S WORK
IX. COMMON ORGANIC COMPOUNDS
An organic compound is one that contains carbon. Or-
ganic chemistry is the study of compounds containing car-
bon. Carbon monoxide, carbon dioxide, carbonic acid, and
the carbonates are organic compounds, but for the sake of
convenience, and because of their common occurrence, they
are usually studied in inorganic chemistry.
The simplest organic compounds are composed of carbon,
hydrogen, and oxygen. The more complex compounds
found in plant and animal tissues are composed of carbon,
hydrogen, oxygen, nitrogen, sulfur, and phosphorus in
varying proportions. These complex bodies are usually
decomposed when heated, leaving a black residue of car-
bon. This is called a "charring test" for an organic
compound.
Some substances, like kerosene, when heated, burn leaving
no residue of carbon. Such substances burn with a lumi-
nous flame that deposits "soot," which is carbon, upon a cool
surface. This is also a test for an organic substance. This
is called the "soot test."
66
TESTS FOR ORGANIC COMPOUNDS
67
There are other substances, like alcohol and ether, which
neither leave a residue nor deposit "soot" when they burn.
If a drop of limewater is held over such a flame, the presence
of carbon dioxide may be detected. This test holds good
for any organic substance, for carbon dioxide is always formed
when such a substance burns.
EXPERIMENT 31
Tests for Organic Compounds
Materials. Flour, sugar, salt, baking powder, wood, milk,
talcum powder, kerosene, gasoline, paraffine, turpentine, olive
oil, lard, ether, limewater, alcohol.
Apparatus. Bunsen burner, evaporating dish, test tubes, stirring
rod.
A. " Charring Test " for an Organic Compound.
1. Heat about 2 grams of flour in an evaporating dish.
Note the results. What remains? Heat the black residue
strongly. Will it burn? Continue heating till the carbon
has entirely disappeared. What is the white ash that re-
mains? Does flour contain organic compounds? Does it
contain inorganic compounds? Clean the dish with sapolio.
2. In like manner heat a very small amount of sugar, salt,
baking powder, wood, milk, talcum powder. Tabulate
your results as follows :
Organic Compounds
Inorganic Compounds
Organic and Inorganic
Compounds
68 COMMON ORGANIC COMPOUNDS
B. " Soot Test " for Organic Compounds Which Do Not Char When
Heated.
1. Heat in a dry evaporating dish 1 cc. of kerosene until
it burns. Is the flame colored? Hold a cold glass plate
in the flame. Result ? What is the black deposit ? Is kero-
sene an organic compound? Is there a residue?
2. In like manner test gasoline, paraffine, turpentine,
olive oil, and lard. State the result in each case.
C. " Carbon Dioxide Test " for Organic Compounds.
1. Heat 1 cc. of ether in an evaporating dish till it burns.
Is the flame colored ? Hold a cold glass plate over the flame.
Does it deposit " soot" ? Obtain 5 cc. of clear limewater in a
clean test tube. Dip the stirring rod in the limewater and
hold the clear drop over the flame. Does the drop become
milky? Explain fully.
2. In the same way test alcohol. Is it an organic com-
pound?
3. Mix 5 grams of sugar with 5 grams of powdered copper
oxide. Place the mixture in a hard-glass test tube fitted with
a delivery tube that dips into 10 cc. of limewater in another
test tube. Heat the mixture. Note the drops of water on the
cool upper portion of the test tube. Explain. Note the
precipitate produced in the limewater. Explain. What is
the reddish material in the test tube? Explain. The re-
actions that take place are as follows :
(1) C12H22On+24 CuO — ^ 11 H20+12 C02+24 Cu
(2) C02+Ca(OH)2 — ^ CaCQ3+H2Q
The carbon dioxide test is the best test for carbon in a com-
pound.
HYDROCARBONS 69
HYDROCARBONS
The hydrocarbons are organic compounds composed of
hydrogen and carbon. Methane CH4, ethane C2H6, and
acetylene, C2H2, are the most common gaseous hydrocarbons.
Gasoline, kerosene, benzene, and turpentine are liquid
hydrocarbons. They contain a greater number of carbon
and hydrogen atoms than do the gases. The solid hydro-
carbons, like paraffine and vaseline, contain a still higher num-
ber of carbon atoms. The gases burn readily. Illuminating
and fuel gases usually contain one or more of them. The
liquids are volatile and inflammable. They are good solvents
for fats and waxes.
Note: For further information concerning the hydrocarbons read almost
any up-to-date elementary textbook on chemistry or a good organic chemistry
such as Norris' " Organic Chemistry," or Stoddard's " Introduction to Organic
Chemistry."
EXPERIMENT 32
Hydrocarbons
Materials. Calcium carbide, gasoline, kerosene, lard or butter,
paraffine candles, chloroform, benzene, carbon tetrachloride.
Apparatus. Test tubes, test tube rack, evaporating dish, stirring
rod.
A. Composition of Hydrocarbons.
1 . Explain how you would prove the presence of hydrogen
in a substance. (See Experiment 12, A.)
2. Explain how you would test for carbon a substance
which does not char when heated. (See Experiment 31,
B and C.)
B. Some Common Gaseous Hydrocarbons.
1. Light the gas from the Bunsen burner. Test for hydro-
gen by the method explained above, i.e. hold a cold object
70 COMMON ORGANIC COMPOUNDS
above the flame and look for drops of water. Does illumi-
nating gas contain hydrogen ? Now explain why a cold flat-
iron or a teakettle filled with cold water becomes wet when
first placed over a gas burner of the kitchen range. Make
the flame colored by closing the hole in the burner. Apply
the test for carbon given above, i.e. hold a cold object in the
flame. Is "soot" deposited? Does illuminating gas con-
tain carbon? Methane is the chief hydrocarbon in illumi-
nating gas. What is its formula ? Write the equation, indi-
cating the products formed when methane burns.
2. Half fill a test tube with water and prepare to work
rapidly. Stand it in the rack and drop into it a piece of cal-
cium carbide about the size of a bean. Note the odor of the
acetylene. Light the escaping gas. Describe the flame.
How can the gas be used for lighting purposes ? The formula
for acetylene is C2H2. Write the equation for the formation
of acetylene from calcium carbide and water. Write the
equation, indicating the products formed when acetylene
burns in the air depositing much soot. With the proper kind
of burner acetylene may be used for illuminating purposes.
Enough air is admitted to completely burn the acetylene and
no soot is formed. Write an equation for the complete
combustion of acetylene.
C. Some Common Liquid Hydrocarbons.
1. Pour 1 cc. of gasoline into an evaporating dish and the
same volume of kerosene into another. (Two students may
perform this test together.) Note the time it takes each to
evaporate. Which is the more volatile ?
2. Test the inflammability of each hydrocarbon by dip-
ping the end of the stirring rod into the liquid and then
HYDROCARBONS 71
bringing it to the tip, of the flame. Which substance is the
most inflammable? Why should you be so careful in using
gasoline near a flame ?
3. Dissolve some fat, such as butter or lard, in kerosene and
in gasoline. Which of these liquids is best to use in cleaning
spots from clothing ? Why ?
4. What is the source of gasoline and kerosene?
5. Benzene has the formula C6H6. It is called an aro-
matic hydrocarbon. Note its odor ; test its inflammability.
What is the source of benzene? WThat are some of the im-
portant commercial products formed from benzene?
D. Solid Hydrocarbons.
1. Paraffine is a solid hydrocarbon. Obtain a paraffine
candle, light it, and prove that it contains hydrogen and
carbon.
2. What is the source of paraffine?
3. What is vaseline ?
E. Chloroform and Carbon Tetrachloride.
Part or all of the hydrogen atoms in methane, CH4, and in
the other hydrocarbons may be replaced by different ele-
ments and radicals. If one hydrogen atom in methane is
replaced by chlorine, raowo-chlor-methane, CH3CI, is formed.
If two are replaced, cZi-chlor-methane, CH2CI2, is formed.
If three are replaced, ^n-chlor-methane, CHCI3, is formed ;
this is chloroform. If four are replaced, ^ra-chlor-methane,
CCU, is formed ; this is carbon tetrachloride.
1. Obtain 5 cc. of chloroform. Note its odor. Place a
drop on your hand. Is it volatile ?
2. Dip the stirring rod into it and hold it in the flame.
Is it inflammable ?
72 COMMON ORGANIC COMPOUNDS
3. Try to dissolve a drop of olive oil in it. Result?
4. Chloroform is an anaesthetic and is a useful and safe
cleansing agent, since it is non-inflammable.
5. Obtain 5 cc. of carbon tetrachloride. Note its odor.
Place a drop on your hand. Is it volatile ?
6. By means of the stirring rod test its inflammability.
Result? Pour some on a burning splint. Result? It is
sold as "Pyrene" for extinguishing fires.
7. Try to dissolve olive oil in it. Result? It is much
used for cleansing purposes. It is the chief constituent of
"Carbona."
ALCOHOLS
Alcohols are organic hydroxides. The hydrogen atoms
in a hydrocarbon may be replaced by elements or radicals.
If a hydrogen atom is replaced by a hydroxy 1 group, we have
an alcohol. For example, the hydrocarbon methane has the
formula CH4. Replace one hydrogen atom by the hydroxyl
group OH and we have CH3OH, which is methyl alcohol, called
wood alcohol. Similarly, the hydrocarbon ethane is C2H6.
Remove one hydrogen atom and replace it by OH and we
have C2H5OH, ethyl alcohol, called common alcohol or grain
alcohol. These organic hydroxides, like the inorganic hydrox-
ides, will combine with acids to form organic salts, called esters.
In every other respect they are unlike inorganic hydroxides.
Although the common alcohols are soluble in water, the
solutions will not conduct an electric current or affect litmus
or feel slippery. Methyl alcohol and ethyl alcohol are
volatile, colorless liquids, having rather pleasant odors.
They are good solvents, good disinfectants, and preserva-
tives.
SOME COMMON ALCOHOLS 73
EXPERIMENT 33
Some Common Alcohols
Materials. Ethyl alcohol, methyl (wood) alcohol, litmus paper,
camphor gum, iodine, a solution of iodine in potassium iodide,
sodium hydroxide, patent medicine, ether, olive oil, carbolic
acid, glycerin.
Apparatus. Stirring rod, evaporating dish, test tubes.
A. Properties of the Common Alcohols.
1. What is the chemical name for common alcohol?
Write its formula. What is the chemical name for wood
alcohol ? Write its formula.
2. Obtain 10 cc. of each liquid in two clean, dry test tubes.
Note the odor of each. Describe the difference.
3. Using a clean stirring rod, taste a drop of each. De-
scribe the difference.
Caution: Do not swallow the liquids — they are poisons. Methyl alcohol
(wood alcohol) produces blindness and death. Ethyl alcohol is a " habit "
producing drug, and produces death ultimately from slow poisoning.
4. Test the solubility of each alcohol in water.
5. Test them with strips of red and with blue litmus.
Do alcohols affect litmus ?
6. Pour 2 cc. of each alcohol in different evaporating
dishes. Apply the flame to each until it burns. Note
the color of the flame and the heat given off by each.
Do alcohols make good fuels ? Which is the most often used
for fuel ? Why ? Could they be used for illuminating
purposes ? Why ? Write the equation to show the products
formed when the alcohols burn.
7. To a test tube half filled with water add a piece of
camphor gum the size of a bean. Does it dissolve? Pour off
74 COMMON ORGANIC COMPOUNDS
the water and add 5 cc. of ethyl alcohol ; shake. Does it
dissolve? This forms the so-called "spirits of camphor. "
Add water to a crystal of iodine. Does it dissolve ? Pour
off the water and add 5 cc. of alcohol. Result? This is
called "tincture of iodine." What are its uses? Is alcohol
a good solvent? Why are flavoring "extracts" largely
alcohol ? Why is it used in patent medicines ? Should
methyl alcohol be used for these purposes ? Why ? Ethyl
alcohol is used to disinfect wounds. Should methyl alcohol
be used for this purpose ? Why ? Ethyl alcohol is used
for " alcohol rubs." Should methyl alcohol be used as
well? Why? Why is methyl alcohol used for preserving
fruits and vegetables in specimen jars rather than ethyl
alcohol ?
8. Summarize the properties of the common alcohols.
9. Summarize the uses of each.
10. What is the commercial source of each?
B. Iodoform Test for Ethyl Alcohol (Grain Alcohol).
1. Alcohol can often be detected by its odor or its taste.
A better test is the following : To 10 cc. of liquid add 5 cc.
of a solution of iodine in potassium iodide. Now add a solu-
tion of sodium hydroxide one drop at a time, shaking the mix-
ture well, till the iodine color vanishes. Warm gently, and
let it stand for a few minutes. A yellow precipitate of iodo-
form with its characteristic odor will be formed. If only a
small amount of alcohol is present, the crystals may not form
but the odor will be recognized.
Try this test upon a solution of 2 cc. of alcohol in 10 cc.
of water.
Test a patent medicine for alcohol.
SOME COMMON ALCOHOLS 75
C. Ordinary Ether (C2H5):0.
Ether is formed by the action of concentrated sulfuric acid
upon ethyl alcohol. It is called, for this reason, "sulfuric
ether" or "ethyl ether."
1. Obtain 5 cc. of ether. Note its odor. Place a drop
on your hand. Is it volatile ?
2. Dip the stirring rod into it and hold it in the flame ?
Is ether inflammable ?
3. Dissolve a drop of olive oil in the ether. Is it a good
solvent? Why then is it not more often used for cleaning
purposes ?
4. What is the important use of ether ?
D. Phenol or Carbolic Acid, C6H5OH.
1. Pure phenol is a white crystalline substance. Examine
a bottle of it, but do not remove any from the bottle.
It is soluble in water. The solution is usually pink due
to slight decomposition, and is called carbolic acid.
2. Obtain 1 cc. of carbolic acid in a test tube. Describe
its odor. Test it with red and with blue litmus. Is it a true
alcohol ? Do not get any on the hands ; it causes serious
burns. Alcohol is the antidote. What is carbolic acid used
for?
E. Glycerin, C3H5(OH)3.
1. Obtain 5 cc. of glycerin in a test tube. Has it an odor?
Taste it. Result? Pour about 1 cc. into another test tube
half full of water. Shake. Is it soluble?
2. Test the solution with litmus. Is it a true alcohol ?
3. What is nitroglycerin? What is dynamite? What
are they used for ?
What important uses has glycerin in the home ?
76 COMMON ORGANIC COMPOUNDS
ORGANIC ACIDS
An organic acid is composed of carbon, hydrogen, and
oxygen. They all contain one or more carboxyl groups,
COOH. They are nearly all crystalline solids. Some acids,
such as acetic, tartaric, citric, and oxalic, have a sour taste
and affect litmus as inorganic acids do. Others such as
stearic, palmitic, benzoic, tannic, and salicylic acids are
almost tasteless. As has been noted, these acids react with
the alcohols (the organic bases) to form esters (organic salts) .
These esters are the basis of many of our artificial flavoring
extracts and perfumes.
EXPERIMENT 34
Properties and Uses of Some Common Organic Acids
Materials. Acetic acid, alcohol, amyl alcohol, concentrated
sulfuric acid, vinegar, tartaric acid, sodium bicarbonate, cream
of tartar, citric acid, oxalic acid, potassium permanganate
solution, tannic acid, ferrous sulfate.
Apparatus. Test tubes.
A. Acetic Acid, H(C2H302) or CH3COOH.
1. Note the odor of a dilute solution of acetic acid.
Very carefully taste it. Test it with litmus paper. Result ?
2. To 3 cc. of acetic acid add 3 cc. of ordinary alcohol,
then, carefully, 3 cc. of concentrated sulfuric acid. Warm
and note the sweet odor of ethyl acetate. This is a test for
acetic acid. Write the equation and name each substance.
C2H5OH+CH3COOH — ^ CH3COOC2H5+H20
Ethyl acetate is an organic salt formed from an organic
acid and an alcohol. These salts are called esters. They
have sweet odors and are often used for artificial flavorings.
PROPERTIES OF SOME COMMON ORGANIC ACIDS 77
To 3 cc. of acetic acid add 3 cc. of amyl alcohol and then
3 cc. of concentrated sulfuric acid. Warm gently and note
the odor of the ester amyl acetate. For what artificial flavor-
ing is it used ?
3. Obtain 3 cc. of vinegar. Smell it, taste it, and test it
with litmus paper. What acid do you think is present?
To prove your answer add alcohol and sulfuric acid as in
(2) and obtain the ester test. What acid is in vinegar?
For what purposes is vinegar used in cooking?
B. Tartaric Acid, Ho(C4H406) or C2H402(COOH)
1. Obtain a crystal of tartaric acid. Describe its taste.
Pulverize the crystal and dissolve a small portion in water.
Test the solution with litmus. Has tartaric acid the charac-
teristic property of an acid ?
Mix the rest of the powdered crystal with an equal amount
of dry sodium bicarbonate. Is there any action? Now
add water. What is given off? Write the equation and
name each substance.
NaHC03+H2C4H406H — ^ HNaC4H406+H20+C02
Tartaric acid is used in baking powders. Why ? (See
Experiment 29 on Carbonates.)
2. Cream of tartar is a salt of tartaric acid HKC4H406
(hydrogen potassium tartrate). Taste it. Dissolve a small
amount in water and test with litmus. Result ? Mix a small
amount with sodium bicarbonate. Is there any action?
Now add water. Result? Write the equation and name
each substance.
HKC4H406+NaHC03 — ^ NaKC4H406+H20+CQ2
78 COMMON ORGANIC COMPOUNDS
3. What is the source of cream of tartar and tartaric acid?
4. What are the little hard " lumps" often found in canned
grapes that have been kept for some time ?
C. Citric Acid, Hs(C^b07) or C3H50(COOH)3.
1. Obtain a crystal of citric acid. Describe its taste.
Dissolve it in water and describe its action on litmus. In
what fruits is this acid chiefly found ? What is its commercial
source ?
2. How may it be used in making artificial lemonade?
D. Oxalic Acid, H2C204 or (COOH)2.
1. Obtain a few crystals of oxalic acid.
Caution : Do not taste them.
Oxalic acid is a poison. In what plants is oxalic acid
found ?
2. Describe the appearance of the crystals.
3. Place the crystals in half a test tube of cold water.
Shake the tube. Result?
4. Now heat the water in the tube. Is oxalic acid more
soluble in hot or cold water? Test the solution with litmus
paper. Result ?
5. Make a stain upon your hand with a solution of potas-
sium permanganate and remove it by applying some of the
solution of oxalic acid that you have just prepared. Wash
the hand thoroughly. A solution of oxalic acid is often used
in preparations for removing stains from the hands and nails.
6. Place a teaspoonful of bleaching powder in 25 cc. of
water. Stir well at two-minute intervals for ten minutes, then
filter. Call the filtrate, Solution No I. Dissolve 5 grams
of oxalic acid in 50 cc. of water. Call this Solution No. II.
This is the common ink eradicator. Try it.
PROPERTIES OF SOME COMMON ORGANIC ACIDS 79
E. Tannic Acid (sometimes called Tannin).
1. Obtain 1 gram of tannic acid. Describe its appearance.
What is its commercial source ?
2. Put it into half a test tube of cold water. Does it dis-
solve ? Heat the tube. Does it dissolve in hot water ? Test
the solution with litmus. Result? Cautiously taste the
solution. Describe the taste.
3. To half of the tannic acid solution add a few drops
of ferric chloride, FeCl3. Result ? This is an ink.
4. To the other half of the solution add a few drops of
ferrous sulfate, FeS04. Notice that the black precipitate
(the ink) is not formed at once, but forms slowly as the
ferrous salt is oxidized by the air to the ferric salt. Tannic
acid and ferrous sulfate are used in the manufacture of inks.
These inks write blue at first because a blue dye is added.
The ink turns black on standing because the ferrous salt is
oxidized to the ferric salt by the oxygen of the air, and ferric
tannate is a deep blue-black.
5. Many plants contain tannic acid. It is in oak bark,
sumach leaves, and the leaves of other trees, in tea leaves, in
coffee berries, in rose leaves, and rose petals.
In making rose beads the crushed wet rose petals are al-
lowed to stand in a rusty iron pan, or powdered "copperas"
(ferrous sulfate) is added. The mass becomes very black.
Explain.
6. Tannic acid makes skins tough and "leathery." It is,
therefore, used in " tanning " hides in the manufacture of
shoes and gloves.
What is one objection to the constant drinking of beverages
containing much tannic acid like strong green tea or strong
coffee ?
80 COMMON ORGANIC COMPOUNDS
F. A Note on Esters.
In A, 2 of this experiment the esters, ethyl acetate and
amyl acetate, were prepared. Ethyl acetate is called artificial
oil of apple. Amyl acetate is artificial banana oil. Artificial
oil of wintergreen is methyl salicylate, the ester (organic
salt) prepared from methyl alcohol (organic base) and sali-
cylic acid (organic acid). Nearly all the oil of winter-
green on the market is the artificial product.
Most esters are more or less fragrant volatile oils. They
are usually insoluble in water but soluble in alcohol, and this
alcoholic solution is called an "extract." These extracts
form the basis of many of our flavoring extracts and perfumes.
Fats are solid esters also insoluble in water but without
odor.
If the alcohol glycerin, C3H5(OII)3, combines with
stearic acid, Ci7H35COOH, an ester glyceral stearate,
(Ci7H35COO)3C3H5, is formed. This is a fat called stearin.
An ordinary fat such as beef tallow is made up largely of this
fat and glyceral palmitate, (CisHaiCOO^CsHs, and glyceral
oleate, (C17fhzCOO)zCJI6.
EXPERIMENT 35
(Class Experiment)
Fuels and Illuminants
Materials. Sawdust, coal, ice.
Apparatus. Test tubes, large glass test tube, side-necked test
tube, delivery tube, clay pipe stem.
A. Solid Fuels.
1. Wood: What woods are the most commonly used for
heating purposes in this region? Which is best? Why?
FUELS AND ILLUMINANTS 81
What are the chief elements in wood? What are the prod-
ucts formed when wood is burned in the air ?
If wood is heated without air entirely different products
are formed. Half fill a hard-glass test tube with small pieces
of hard wood or sawdust. Clamp the test tube in a hori-
zontal position on the ring stand. By means of a right-angled
delivery tube attach the hard-glass test tube to a side-necked
test tube by means of two well-fitted one-holed stoppers.
Attach a jet to the side-necked test tube. Keep the side-
necked test tube cool by standing it in a beaker of ice water.
Heat the wood till no further change takes place. Test the
gas that escapes from the side-necked test tube. Will it
burn ?
When the hard-glass tube is cold examine the contents.
Remove the black residue. What is it?
Note the odor of the liquid in the side-necked test tube.
Test with litmus. Result? Is water formed when wood is
decomposed? Is an acid formed? What acid chiefly?
What compounds are made commercially by heating hard
wood in the absence of air ?
When a substance is heated in the absence of air, the process
is called destructice distillation.
2. Coal: What is the source of coal ? Of what is it chiefly
composed? What are the products formed when it is com-
pletely burned in air?
Half fill a hard-glass test tube with small pieces of soft coal.
Clamp the test tube in a horizontal position on the ring
stand. Set up the apparatus as in A. Heat the coal till
no further change takes place. What is the gas that is
formed? What remains in the hard-glass tube? What is
the gas that is formed ? What collects in the side-necked test
82 CHEMISTRY OF FOODS
tube? Test for an acid. Result? Test for a sulfide. What
commercial products may be obtained by the destructive
distillation of coal ?
B. Liquid Fuels and Illuminants.
1. Alcohol: Why is grain or ethyl alcohol not more com-
monly used for fuel ? What is the color of the alcohol flame ?
Could it be used for illuminating purposes ?
2. Crude Petroleum: This fuel is used in many furnaces
where intense even heat is needed. Visit the furnace room
at your school or the large range in the lunch house and note
the intense heat produced by the burning jet of crude oil.
Describe the burner.
3. Gasoline: What is the source of gasoline? Can it be
used for fuel ? How ? Can it be used for lighting purposes ?
How?
4. Kerosene: What is the source of kerosene? How can
it be made to burn with a blue flame ?
C. Gaseous Fuels and Illuminants.
Some of the gases used for fuels and illuminants are natural
gas, coal gas, and acetylene. What is natural gas ?
Explain how the same gas can be used either for lighting
purposes or for fuel. What is a Welsbach mantle ? Explain
its use.
X. CHEMISTRY OF FOODS
In studying the chemistry of foods, the Food Chemistry
outline in the Appendix of this manual will be found useful.
The following are good reference books :
Bulletin No. 28, U. S. Department of Agriculture, Appendix A.
Bulletin No. 13, American School of Home Economics.
WATER IN FOODS 83
Weed, Chemistry in the Home.
Wellman, Food Study.
Sherman, Food Products.
Snell, Elementary Household Chemistry.
Leach, Food Inspection and Analysis.
Brownlee, Fuller, and others, Chemistry of Common Things.
INORGANIC CONSTITUENTS OF FOODS
EXPERIMENT 36
Water in Foods
Materials. White bread, milk, meat, potato.
Apparatus. Laboratory balances, drying oven, evaporating dish.
A. The Presence of Water in Foods.
How is the presence of water in food determined ? (See
Experiment 12 C.) Test four foods for water.
B. The Amount of Water in Foods.
1. To determine exactly how much water a substance
contains it is weighed, then dried and weighed again. The
loss in weight is the weight of the water that was in the
substance. Divide the weight of the water by the weight
of the substance before drying and multiply the result by
100 to give the per cent of water in the substance.
Find the per cent of water in bread as follows : Label your
evaporating dish with your name and weigh it. Obtain the
largest cube of bread that will go into the dish and weigh both
as carefully as you can on the laboratory balance. Place the
dish and the bread in the drying oven for about six hours,
keeping the temperature below 106° C. Why? When
completely dry cool and weigh. Tabulate the results as
follows :
84 CHEMISTRY OF FOODS
(a) Weight of empty dish = g.
(b) Weight of dish and bread before drying = g.
(c) Weight of dish and bread after drying = g.
(d) Weight of bread (b)-(a) = g.
(e) Weight of water in bread (5) — (c) = g.
(/) Per cent of water in bread (e) h- (d) X 100 = %
2. From the table in the Appendix make a list of five
foods which contain much water (80 %-100 %), five which
contain a medium amount of water (15 %-S0 %), and five
containing very little water (less than 15 %).
3. What tissues of the body contain much water? What
tissues contain the least water?
4. Of what use is water to the body ?
INORGANIC SALTS IN FOODS AND BONES
EXPERIMENT 37
Inorganic Salts in Foods (Mineral Matter or Ash)
Materials. Bones that have soaked for at least two days in
hydrochloric acid, ammonium hydroxide, milk, meat, potato,
bread.
Apparatus. Porcelain crucibles, clay triangle, evaporating dish.
A. Inorganic Salts in Foods.
Inorganic salts do not burn; they remain as ash, when
the organic matter of the food has been burned away.
1. To show the presence of inorganic salts in a food place
about 1 gram of the food in a porcelain crucible and heat
with the crucible inclined. In this way, heat milk, meat,
potato, and bread.
(Four students may work together, the first heating milk,
INORGANIC SALTS IN FOODS (MINERAL MATTER OR ASH) 85
the second meat, etc. Each student should make observa-
tions and reports on four foods.)
2. From the table in the Appendix make a list of foods
containing much mineral matter and a list of foods contain-
ing little or no mineral matter.
B. To Show the Presence of Inorganic Salts in Bones.
1. Clean a small bone by boiling in water. Place the
clean bone in a beaker of hydrochloric acid and allow it to
stand for two days. Explain the change that has taken
place in the bone. Keep the bone.
2. Place 10 cc. of the clear liquid in an evaporating dish
and evaporate to dryness. What is the dry residue that
remains ?
3. Prove the presence of calcium salts in the ash by dis-
solving it in 5 cc. of hydrochloric acid. Filter. Make the
solution alkaline with ammonium hydroxide. What is the
white precipitate chiefly?
4. What tissues of the body contain much mineral matter
and what tissues very little ?
CARBOHYDRATES
Carbohydrates are organic compounds which form the
most important part of our foods. They contain no nitro-
gen (non-nitrogenous). They are composed of carbon,
hydrogen, and oxygen, the hydrogen and oxygen usually
being present in the proportion in which it is found in water,
that is, twice as many atoms of hydrogen as oxygen. The
starches and the sugars are the most important carbohydrates
found in foods.
86 CHEMISTRY OF FOODS
The Starch Group (C6Hi0O5)»
EXPERIMENT 38
Starch and Dextrin
Materials. Corn starch, rice starch, wheat starch, potato starch,
dextrin, concentrated sulfuric acid, Fehling's solution, dilute
sulfuric acid, sodium carbonate, litmus paper, iodine solution,
potato, meat, milk, apple, banana, nuts, rolled oats, raisins.
Apparatus. Test tubes, microscope, labels, asbestos mat.
A. Properties of Starch.
1. Obtain about one gram of corn starch, rice starch,
wheat starch, and potato starch in separate tubes. Is there
any difference in the appearance of each ?
2. Mount a few grains of each on microscope slides and
draw the appearance of each under the high power.
3. Add 10 cc. of water to each tube. Shake the mixture
well and then let it stand for one minute. Does starch
dissolve in cold water ?
4. Shake the mixture of corn starch and water again and
then boil it for a few minutes. (Keep this for 9.)
5. Gently heat a little corn starch in a dry test tube until
it becomes brown. What is formed ? Taste it. Try the
solubility of some pure dextrin in water. What is dextrin
used for? Why is the brown crust of bread sweet?
6. Heat strongly one gram of starch in a dry test tube.
What collects on the sides of the tube ? Explain. What re-
mains in the tube ? What does this show about the composi-
tion of starch ? Write an equation to show what took place.
7. Add a few drops of concentrated sulfuric acid to some
dry starch in a test tube. Warm gently. Explain results.
How does this also show the composition of starch?
STARCH AND DEXTRIN 87
8. Burn a small lump of starch on your asbestos mat.
What products are found ? Write an equation to illustrate.
9. To 5 cc. of starch paste prepared in (4) add 5 cc. of
Fehling's solution and boil. Result? (To prepare Feh-
ling's solution, see Appendix.)
10. To 10 cc. of starch paste add 10 cc. of dilute sulfuric
acid. Boil for five minutes. Add solid sodium carbonate
till the mixture is alkaline to litmus, then add Fehling's solu-
tion and boil. Result?
Note : If a red precipitate is not obtained, try again. The starch combines
with a molecule of water to form glucose (grape sugar). Glucose is a reducing
sugar and reduces the copper sulfate in the Fehling's solution to cuprous oxide.
Cuprous oxide is the red precipitate. When a substance like starch takes
up water and becomes a new substance, it is said to hydrolyze. The process is
called hydrolysis. There are several ways of hydrolyzing substances : (i) By
boiling with a dilute acid, (2) boiling with a base, (3) by means of an enzyme or
ferment.
How is starch caused to hydrolyze? Could any acid be
used other than sulfuric acid? Write this equation for the
hydrolysis of starch and name each substance :
C6H10O5+H2O (by means of H2S04) — >■ C6H1206.
B. The Iodine Test for Starch.
1. Obtain about 10 cc. of a solution of iodine in one of
your clean test tubes. To some dry starch add about 1 cc,
of iodine solution. Results?
2. To a test tube half full of water add two drops of cold
starch paste. Shake well, then add about two drops of the
iodine solution. Results? Boil till the color disappears,
then cool again and the color will return if you have not
boiled it too long. This is called the iodine test for starch.
3. To detect the presence of starch in foods the food should
(1) be broken into small pieces or powdered. Why? (2)
88
CHEMISTRY OF FOODS
It should be boiled two or three minutes in water. Why?
(3) It should be cooled. Why? (4) Two drops of iodine
solution should be added.
4. Test the following foods for starch according to the
method above and record the results in a table : potato,
meat, milk, apple, banana, nuts, rolled oats, raisins.
Of what use to the body is starch?
Much Starch
Little Starch
No Starch
CELLULOSE
Cellulose forms the walls of the cells of plants. It is
most abundant in the roots and stems, less in the leaves, and
least in the fruit. "Seed hairs" are almost pure cellulose.
Since cotton fibers are seed hairs, cotton is almost pure cellu-
lose. The fiber in young tree trunks is used for paper.
Cellulose is not digestible, but it forms an important part of
food, for it gives it the needed bulk.
EXPERIMENT 39
Cellulose
Materials. Carrots, beets, celery, potato, cabbage, lettuce, ap-
ples, grapes, dilute hydrochloric acid, dilute sodium hydroxide,
solid sodium carbonate, zinc chloride, Schweitzer's reagent (see
Appendix), concentrated nitric acid, alcohol, ether.
Apparatus. Test tubes, beaker.
CELLULOSE 89
A. Occurrence of Cellulose, (C6Hi0Oo)«.
1. Examine carefully roots (carrot, beet), stems (celery,
potato), leaves (cabbage, lettuce), and fruits (apples, grapes).
Draw the position of the chief cellulose fibers in each.
2. Name five vegetables or fruits with much cellulose
and five with little or no cellulose.
B. Properties of Cellulose.
1. Test the solubility of cellulose (a small amount of cot-
ton in each case) in water, dilute hydrochloric acid, dilute
sulfuric acid, and dilute sodium hydroxide. What is the
result in each case? Is the cellulose digestible? Of what
value is it in the foods?
2. Test cellulose (cotton) with a solution of iodine. Re-
sult?
3. Test cellulose (cotton) with Fehling's solution. Re-
sult after boiling ?
4. Cover a little cotton in a test tube with concentrated
sulfuric acid. Allow it to stand two minutes. Neutralize
the acid with sodium carbonate (till effervescence ceases and
it turns red litmus blue). Now add Fehling's solution and
boil. Explain and write equations. What possible use
does this suggest for old papers and rags ?
5. (Instructor) : Test the solubility of cellulose in a solu-
tion of zinc chloride in concentrated hydrochloric acid.
6. (Instructor) : Prepare a fresh solution of cuprous
ammonia or Schweitzer's reagent according to the method
given in the Appendix. Show the solubility of cellulose in
this solution. Reprecipitate the cellulose by adding hydro-
chloric acid. This is a test for cellulose.
7. (Instructor): Prepare " nitro-cellulose " or "guncot-
90 CHEMISTRY OF FOODS
ton" and "collodion" by mixing 20 cc. of concentrated
sulfuric acid and 10 cc. of concentrated nitric acid. Cool
this to room temperature. Immerse absorbent cotton or
clean cotton gauze in this mixture for about one minute.
Wash well with cold water, wring it out, and hang it up to
dry. This is "gun cotton."
Burn a piece of guncotton and compare with the burning
of untreated cotton.
Shake a portion of the dry guncotton in a mixture of
equal parts of alcohol and ether. The clear solution is
"collodion." Place a little in a glass plate and allow it to
stand. Result? What is collodion used for? What is
" New Skin " ? What is celluloid ?
8. Is cellulose digested? Is it of use in foods? Explain.
GUMS AND PECTIN
Gums are compounds closely related to the carbohydrates,
having very complex constitutions. They are generally solu-
ble in water but not in alcohol. The water solutions when
cold form jellies, or sticky mucilage-like solutions.
Pectin is a carbohydrate found in fruits, which causes the
juices to " jelly " when boiled with sugar. Pectin will produce
a jelly only in the presence of at least half of one per cent of
acid. Sugar also helps to precipitate the pectin and to form
the jelly.
EXPERIMENT 40
Gums and Pectin
Materials. Gum arabic or gum tragacanth, agar-agar or Iceland
moss, iodine solution, Fehling's solution, concentrated sulfuric
acid, solid sodium carbonate, alcohol, cranberries.
Apparatus. Test tubes, beaker.
GUMS AND PECTIN 91
A. Gums.
1. Note carefully the physical properties of gum arabic
and agar-agar with special reference to color, odor, taste, and
form.
2. Dissolve about one gram of gum arabic in a half test
tube of boiling water. Boil one minute. Cool the solution.
What is formed ? Repeat, using agar-agar. What is formed ?
3. To about 1 cc. of the cool gum arabic solution add a
few drops of iodine solution. Result? Repeat, using agar-
agar. Result ?
4. To about 1 cc. of the gum arabic solution add Fehling's
solution and boil. Result? Repeat, using agar-agar. Re-
sult?
5. To the remainder of the gum arabic solution add (cau-
tiously) 5 cc. of concentrated sulfuric acid and boil two
minutes. Add solid sodium carbonate till the acid is neu-
tralized, then add Fehling's solution and boil. Explain.
6. Try to dissolve one gram of gum arabic in alcohol.
Result? Repeat, using agar-agar. Are gums soluble in
alcohol ?
7. How are some of the gums used in the preparation of
foods?
8. Give some of the commercial uses of gums. Why is
it used by bacteriologists for culture media ?
B. Pectin.
1. Slice five cranberries in your beaker, add 50 cc. of
water, and boil ten or twenty minutes. Filter while hot.
2. To 15 cc. of the clear filtrate add 15 cc. of alcohol.
Result? (A jelly-like precipitate of pectin should be formed.
This is a test for pectin in fruits.)
92 CHEMISTRY OF FOODS
3. To 15 cc. of the clear filtrate add 10 grams of sugar and
boil for ten minutes. Cool. A jelly indicates the presence
of pectin.
Do cranberries contain pectin?
4. To the remainder of the filtrate add 5 cc. of concen-
trated sulfuric acid. Boil for five minutes. Neutralize
the acid with solid sodium carbonate. Then add Fehling's
solution and boil. Result? (Like starch, pectin is hydro-
lyzed to reducing sugars by long boiling with a dilute acid,
or by boiling for a short time with a strong acid.)
5. Summarize the necessary precautions to be observed
in making jelly.
6. What fruits contain much pectin? Which contain
very little ?
7. Repeat B, 1 and B, 2, using an apple and one other
fruit. Report the presence or absence of pectin.
Test also a beet for pectin. Could jelly be made from a
beet?
SUGARS
The sugars are carbohydrates widely distributed in nature.
They form crystals and dissolve in water. They have a
sweet taste. There are two groups of sugars : (1) The
monosaccharides or monoses, including glucose, fructose, and
gelactose having the general formula C6Hi206, and (2) the
disaccharides or dioses, including sucrose, lactose, and maltose
having the general formula C12H22O11.
Glucose called grape sugar or dextrose is found in grapes.
Fructose called fruit sugar or levulose is formed with glucose
when sucrose is hydrolyzed. Gelactose is formed with
glucose when lactose is hydrolyzed.
SUGARS 93
EXPERIMENT 41
Sugars
Materials. Sucrose (cane sugar), lactose (milk sugar), dextrose
(grape sugar), in five-gram portions, concentrated sulfuric acid,
iodine solution, Fehling's solution, dilute sulfuric acid, solid so-
dium carbonate, raisins, honey, rice, beets, lemons, flour.
Apparatus. Test tubes, small beaker.
A. Physical Properties of Sugars.
1. Obtain 5 grams of sucrose or cane sugar, C12H22O11.
Note its form and taste. Place about 1 gram in a test
tube half full of cold water. Result?
2. Obtain 5 grams of lactose, milk sugar, C12H22O11, and
note its form and taste. Place about 1 gram in a test tube
half full of cold water. Heat the water. Is it more soluble
in hot or in cold water ? Is it as sweet as cane sugar ? Is
it as soluble as cane sugar?
3. Repeat (2), using grape sugar, C6H12O6, sometimes called
glucose or dextrose. Is it as sweet as cane sugar? Is it
as soluble? Will it crystallize as easily?
B. Chemical Properties of Sugars.
1 . Place about one gram of sucrose in a dry test tube and
heat until it melts. This is called barley sugar and when
cool it forms a pale yellow glassy mass.
Heat more strongly. Note the change in color, odor, and
taste. What is the brown sirup formed?
Now heat the tube intensely until the substance decom-
poses. What collects on the cool sides of the test tube?
What remains in the tube? What does this prove con-
cerning the composition of cane sugar (sucrose) ? Is it true
94 CHEMISTRY OF FOODS
carbohydrate? What is its formula? Write the equation
to show its complete decomposition.
2. In like manner heat 1 gram of lactose until it is com-
pletely decomposed. Result? Is it also a true carbo-
hydrate? What is its formula? Write the equation to
show its complete decomposition.
3. Repeat (2), using grape sugar. Is it a true carbohy-
drate? What is its formula? Write the equation to show
its complete decomposition.
4. Place 1 gram of each sugar in three different test tubes
and cover with concentrated sulfuric acid. Warm if neces-
sary. Note the results in each case and explain fully. Write
an equation in each cas^ to show the decomposition of the
sugars by acid. This is a second method to prove sugars
to be carbohydrates.
5. Dissolve one gram of each sugar in hot water in separate
test tubes, cool, and add a few drops of iodine solution to each.
Do sugars affect iodine solution ?
6. Dissolve 1 gram of grape sugar in hot water, add 5 cc. of
Fehling's solution, and boil. A red or yellow precipitate of
cuprous oxide, CU2O, is formed. Grape sugar reduces the
copper sulfate in the Fehling's solution to cuprous oxide
which forms the red precipitate. Such a sugar is called a
reducing sugar.
7. Dissolve 1 gram of sucrose, cane sugar, in water, add
Fehling's solution, and boil. Is sucrose a reducing sugar?
8. Repeat (7), using lactose. Is lactose a reducing
sugar ?
9. Place 5 grams of sucrose in your small beaker. Dissolve
in 25 cc. of water. Add 10 cc. of dilute sulfuric acid and
boil 1 minute. Now add solid sodium carbonate until the
SUGARS 95
solution is alkaline to litmus, then add Fehling's solution and
boil. Is a reducing sugar present?
The sugar is hydrolyzed as was starch in Experiment 38.
In this case two reducing sugars are formed, dextrose and
levulose. Both have the formula C6Hi206. Write the
equation for the hydrolysis of sucrose, naming each substance.
C12H22On+H20 (by means of H2S04) ^ C6H1206+C6H1206
Now explain why lemon juice or vinegar is used in making
taffy or in general to prevent the graining of cane sugar
sirup.
10. Glucose is a fermentable sugar, alcohol and carbon
dioxide being formed.
C6H1206+yeast — ^2 C2H5OH+2 C02
Lactose and cane sugar are not fermentable by pure yeast.
An enzyme contained in the yeast hydrolyzes these sugars,
forming some glucose. Then the glucose formed ferments.
11. Summarize the results of the tests on the three sugars
in a table under the following heads : Taste as compared
with cane sugar. Solubility in water. Action of intense
heat. Result of boiling with dilute acids. Action of
Fehling's solution. Action of pure yeast.
C. Method of Testing Foods for Reducing Sugars.
1. Boil the substance in water after breaking it into small
pieces, add Fehling's solution and boil again. A red precipitate
of cuprous oxide indicates the presence of a reducing sugar.
2. Test the following foods for a reducing sugar. Name
the sugar present if possible, (a) Raisins, (b) Honey, (c)
Rice, (d) Meat, (e) Beet, (/) Lemon, (g) Flour.
3. Of what use are the sugars to the body?
96 CHEMISTRY OF FOODS
FATS AND OILS
A fat is an ester. An ester is the organic salt formed
when an alcohol (organic base) combines with an organic
acid. When the alcohol glycerin, C3H5(OH)3, combines
with stearic acid, Ci7H35COOH, the fat glyceryl stearate
(stearin), (CnHasCOO^CsHs, is formed.
If glycerin combines with palmitic acid, C15H31COOH, the
fat glyceryl palmitate, (C^HsiCOO^CsH^ (palmitin), is
formed.
If glycerin combines with oleic acid, C17H33COOH, the fat
glyceryl oleate, (Ci7H33COO)3C3H5 (olein), is formed.
Ordinary fats are mixtures of these three fats. In solid
fats, stearin and palmitin predominate. In oils olein pre-
dominates.
Fats are non-nitrogenous, organic compounds. They
are composed of carbon, hydrogen, and oxygen, but they
are by no means carbohydrates.
EXPERIMENT 42
Fats and Oils
Materials. Lard, olive oil, butter, cottonseed oil, gasoline, ether,
chloroform, carbon tetrachloride, solution of egg albumen in
water, iodine solution, Fehling's solution, sodium hydroxide 4 N,
Sudan III, castor beans, boiled egg yolk, walnuts, chocolate,
grated cheese.
Apparatus. Test tubes, evaporating dish, beakers.
Note : Do not throw fats or oils into the sink, put them in the jars
A. Physical Properties of Fats and Oils.
1. Obtain about 5 grams of each of the following : lard,
olive oil, cottonseed oil. What is the source of each?
FATS AND OILS 97
2. Note the color, odor, and taste of each. Are they
soluble in water? To the tubes add respectively 50 cc. of
gasoline, ether, chloroform, and carbon tetrachloride.
Caution: Have no flames near.
Shake well and then look for the oil. Result? Now ex-
plain how a grease spot on clothing may be removed by one
of these solvents. Which is the best to use? Why? In
removing a grease spot why apply solvent at the outside
and work toward the center of the spot ?
3. Place 1 cc. of olive oil in a test tube. Add 5 cc. of a
solution of egg albumen in water. Shake vigorously for a
minute. Result? This is called an emulsion. Let it
stand and note that in time the oil will come to the top.
The more perfect the emulsion the longer it will take for the
oil to separate out. Milk is an example of a natural emul-
sion. Mayonnaise dressing is an example of a prepared emul-
sion. The disagreeable taste of castor oil is masked by
preparing an emulsion by first adding orange juice, then
baking soda, and stirring rapidly.
B. Chemical Properties of Fats and Oils.
1. In a test tube place a lump of lard about the size of
a bean. Add 5 cc. of a solution of iodine. Result?
2. In another test tube place the same amount of lard
and add 5 cc. of Fehling's solution and boil. Result?
3. In a clean evaporating dish place 2 grams of lard ; warm
gently. Result? Heat the lard more and more strongly
and note results. The strong, irritating odor from hot lard
or other fats or oils is due to the formation of acrolein.
4. To three drops of cottonseed oil add J test tube of
sodium hydroxide and boil for a minute or until the oil can
98 CHEMISTRY OF FOODS
no longer be seen. A soap is formed. The process is called
saponification. Write two equations to show the reactions
that took place. Name all substances.
C. Tests for Fats and Oils.
1. The reagent Sudan III stains fats and oils. Cut open a
castor bean or a sunflower seed ; apply a drop of the reagent.
Result? In like manner test boiled egg yolk for fat.
2. Some substances contain sufficient fat to give the
"grease spot" test. Rub a piece of walnut on a page of
your scratch pad placed on the table. Is a grease spot
formed? Warm the spot over the burner. It should not
disappear. In this way test chocolate.
3. The fat may be extracted from the substance by mixing
well with ether or gasoline. The gasoline will dissolve the
fat and then if allowed to evaporate, the fat will be left.
Put about 10 grams of grated cheese in one of your
beakers. Add 25 cc. of gasoline ; stir well.
Caution: Have no flames near.
Filter into your beaker and allow the filtrate to evapo-
rate. What remains in the beaker?
4. What is the use of fats to the body ? From the Appen-
dix make a list of 10 foods containing much fat (80 % to 100 %).
Make a list of 10 foods containing very little or no fat (10%
to none) . Name five fats or oils of commercial value and give
their uses.
NITROGENOUS SUBSTANCES
Nitrogenous substances are very complex compounds,
found in some plant and nearly all animal tissues. The
most important nitrogenous substances are called proteins.
They are composed of carbon, hydrogen, oxygen, and about
THE ALBUMENS AND CASEIN 99
14 % of nitrogen with varying amounts of sulfur and phos-
phorus. The proteins may be classified into four groups :
(1) Those soluble in cold water and coagulated by hot water,
called the albumens (egg albumen, blood albumen, milk
albumen). (2) Those soluble in hot or cold water (casein
in milk). (3) Those not soluble in hot or cold water, called
globulins (myosin in meat, gluten in flour, and legumen in
peas and beans) . (4) Those soluble in hot water but not in cold,
called albuminoids or gelatinoids because when the hot solu-
tion is allowed to cool a jelly is formed (collagen from skin,
cartilage, and bones, and keratin from hair, horns, and hoofs).
EXPERIMENT 43
The Albumens and Casein
Materials. Fresh egg albumen, concentrated nitric acid, am-
monia, Millon's reagent, dry blood albumen, dry egg albumen,
soda lime, red litmus paper, fresh milk, rennin, dilute hydro-
chloric acid or acetic acid.
Apparatus. Test tubes, funnel, filter paper, evaporating dish,
stirring rod.
A. The Albumens (Soluble in Cold Water, Coagulated by Hot Water).
1. Obtain 1 cc. of fresh egg albumen in a test tube. Note
its physical properties. Add 20 cc. of cold water and shake
well. Does it dissolve?
2. Heat the solution of egg albumen. Result?
3. Filter the coagulated albumen and place a portion of
it in your evaporating dish. Heat slowly and note the pecul-
iar odor of burning protein. Explain. This is the " burn-
ing test" for proteins.
4. To another portion of the coagulated albumen add
100 CHEMISTRY OF FOODS
E
concentrated nitric acid till the albumen is covered. Warm
gently. Result? Now pour off the acid, rinse with water,
and add ammonia. Result? This is the xanthoproteic
test for proteins.
5. Obtain about 10 cc. of blood albumen in water. Add
1 cc. of Millon's reagent and boil. Result? This is Millon's
test for proteins.
6. Obtain 2 grams of dry blood or egg albumen, mix with
soda lime, and heat in a test tube. Note the odor and hold
a piece of moist red litmus at the mouth of the tube. What
is the gas given off? Explain. This is the decomposition
test for proteins.
7. Obtain 20 cc. of fresh milk in your evaporating dish
and heat. What are the scums formed ? By means of the
stirring rod place some of the scum in a test tube and apply
the xanthoproteic test (see 4 above). Result?
B. Casein (Soluble in Hot and Cold Water).
1 . Is casein soluble in hot water ? How do you know ?
2. To a portion of the milk used in A, 7 add dilute hydro-
chloric acid or acetic acid. Result ?
To another portion add rennin and warm gently. Allow
it to cool for five minutes. Result?
3. To a part of the casein apply the burning test. Result ?
4. Apply the xanthoproteic test. Result ?
5. Apply the Millon's test. Result?
6. Apply the decomposition test, using soda lime. Result ?
Questions
1 . If albumen and casein were in a solution together, how
could you separate one from the other ?
2. What are some of the tests for albumen and casein ?
THE GLOBULINS AND ALBUMINOIDS 101
EXPERIMENT 44
The Globulins and Albuminoids
Note to instructor: Have part i of A done at home. The gluten loaves
should be submitted for approval and credit.
Materials. Flour, nitric acid, ammonia, Millon's reagent,
soaked beans, bones soaked in hydrochloric acid for a week,
soup bones, hair or feathers, sodium hydroxide 4 N, sodium
plumbite solution.
Note: Sodium plumbite solution may be prepared by adding sodium
hydroxide to lead acetate solution until the precipitate first formed dissolves
on heating.
Apparatus. Muslin bag, test tubes, evaporating dish.
A. The Globulins (Insoluble in Hot or Cold Water).
Gluten is the globulin found in wheat and other cereals.
1. Into a cup full of flour stir just enough water to make a
heavy dough. Place the dough in a muslin bag and knead
it in the hand in a running stream of water till the water
runs through clear. What part of the flour is removed in
this manner? Examine the gluten remaining in the bag.
What are its physical properties? Is it soluble in cold
water? Leave about one fourth of the gluten in the wet
muslin bag and take it to the laboratory for the chemical
tests. Bake the other three fourths in a moderate oven.
Result ? Take the gluten loaf to the instructor for credit.
2. Place a piece of unbaked gluten about the size of a
bean in a test tube ; add water and boil. Is gluten soluble
in hot water ?
3. Place a similar piece in your evaporating dish. Heat
and note the odor.
4. Apply the xanthoproteic test. Result ?
102 DIGESTION OF FOOD
5. Apply the Millon's test. Result? Is gluten a true
protein ?
6. Myosin is the globulin found in meat. Burn a small
piece of meat and note the odor. Apply the xanthoproteic
test. Result?
7. Legumen is the globulin in peas and beans. Burn
half a bean that has soaked overnight. Result? Apply
the xanthoproteic test to half a soaked bean. Is a protein
present ?
B. Albuminoids or Gelatinoids (Soluble in Hot Water, Forming Jellies
on Cooling).
Collagen is the protein found in cartilage, skin, and bones.
1. (Instructor's experiment.) Boil for some time a soup
bone (chiefly tendons and bone). Strain off the clear liquid
and cool it. A jelly is formed.
2. Soak bones in hydrochloric acid for 2 or 3 days or a
week. Neutralize the acid with sodium carbonate. Then
boil the soft bone. Allow to cool. A jelly is formed. Com-
mercial gelatine is made from bones.
Keratin is a very insoluble protein containing much sul-
fur. Found in hair, hoofs, and nails.
3. Burn some hairs or feathers and note the odor.
4. Boil some hair or feathers with strong NaOH. Add
sodium plumbite solution. A black precipitate of lead
sulfide shows the presence of sulfur in keratin.
XI. DIGESTION OF FOOD
The body is composed of water, proteins, fats, and mineral
matter. The average daily ration contains about 100 grams
of protein, 100 grams of fat, and 420 grams of carbohydrates,
DIGESTION OF STARCH 103
and over a liter of water. Before the proteins of food can
enter the blood to build the body, they must be dissolved.
Before the fats can enter the blood, they must be emulsified
or saponified. Before the carbohydrates can enter the
blood to furnish heat and energy to the body, they have to
be dissolved and changed to simple sugars. These changes
in the food we eat are brought about by various juices in
the digestive tract. The process is called digestion.
In the study of the digestion of foods the following books
are suggested for reference.
1. Appendix in this manual
2. Halliburton, Physiological Chemistry.
3. Snell, Elementary Household Chemistry.
4. Hawk, Practical Physiological Chemistry.
5. Hutchison, Food and Dietetics.
6. Mathews, Physiological Chemistry.
EXPERIMENT 45
Digestion of Starch
Materials. Red litmus paper, Fehling's solution, iodine solu-
tion, clean, freshly prepared corn starch paste, pancreatin, bile
(oxgall), sodium carbonate solution.
Apparatus Test tubes, thermometer (Fahrenheit or centi-
grade), tireless cooker.
A. Action of Saliva on Cooked Starch.
1. Allow some clear saliva to run from the mouth into a
clean test tube. Place a piece of red litmus paper in the
mouth, and while holding it there test the saliva in the test
tube with Fehling's solution. Result?
104 DIGESTION OF FOOD
2. Now remove the litmus paper from the mouth. Is
saliva alkaline or acid?
3. Test 1 cc. of freshly prepared corn starch paste with
Fehling's solution. Result?
4. Now put about half a teaspoonful of the same paste
in the mouth and hold it for a minute. Chew it in order
that the starch may be well mixed with the saliva. Note
that the taste becomes sweet.
5. Put the paste from the mouth into a test tube. Add
Fehling's solution and boil. Result? What is the effect
of saliva on boiled starch ?
6. What is the source of the saliva ? What is the ferment
in the saliva that changes the starch? Will this ferment
act upon uncooked starch or upon cellulose ?
B. Action of Pancreatic Juice on Starch. (Instructor's Experiment.)
The pancreatic juice comes from the pancreas. It acts
in the small intestine in an alkaline solution. The ferment
in the pancreatic juice that acts upon starch is amylopsin.
1. Dissolve 3 grains of pancreatin in 100 cc. of lukewarm
water. Test 3 cc. with iodine and with Fehling's solution.
Result?
2. Dissolve 3 grams of bile (ox gall) in 100 cc. of luke-
warm water. Test 5 cc. with iodine and with Fehling's solu-
tion. Result?
3. Obtain three test tubes. To test tube No 1 add 5
cc. of starch paste and 20 cc. of pancreatin solution. To
No. 2 add 5 cc. of starch paste and 20 cc. of bile solution.
To No. 3 add 5 cc. of starch paste, 5 cc. of bile, 15 cc. of
pancreatin, and 5 cc. of dilute sodium carbonate. Keep all
the tubes in a water bath at a temperature of 98° F. or
DIGESTION OF PROTEINS 105
36.6° C. (temperature of the normal human body) for 24
hours. This can be satisfactorily done by means of a tireless
cooker.
4. Remove the tubes. Test the contents of each for
starch by the iodine solution and for sugar by means of the
Fehling's solution. In which case was digestion most com-
plete? Why?
Questions
1. You eat a piece of -cake. Explain all the changes the
starch undergoes before it is ready for the blood.
2. Explain what changes cane sugar must undergo before
it is digestible. (See Appendix.)
3. Of what use are carbohydrates to the body?
EXPERIMENT 46
Digestion of Proteins
Materials. Minced egg albumen from a hard-boiled egg, pepsin
solution prepared by dissolving 1 g. of pepsin in 500 cc. of
water, 5 N solution of HC1, pancreatin solution prepared by dis-
solving i g. of pancreatin in 500 cc. of water, sodium carbonate
solution made by dissolving 1 g. of sodium carbonate in 100
cc. of water.
Apparatus. Test tubes, thermometer, tireless cooker or water
oven.
A. Action of Gastric Juice. (Instructor's Experiment.)
The saliva has no action on proteins. The gastric juice
comes from the walls of the stomach. It consists of water,
acids (hydrochloric acid chiefly), and several ferments. The
ferments that act upon protein are rennin and pepsin.
1. What is the action of hydrochloric acid upon dissolved
106 DIGESTION OF FOOD
proteins like casein and albumen in milk ? (Recall Experi-
ment 43, B, 2.)
2. What is the action of rennin upon such proteins ? (See
also Experiment 43, B, 2.)
3. Mince well in a clean mortar the coagulated egg al-
bumen of a hard-boiled egg. In each of 4 test tubes place
about 3 grams of egg albumen. To tube No. 1 add 20 cc.
water. To test tube No. 2 add 20 cc. hydrochloric acid.
To No. 3 add 20 cc. of the pepsin solution. To No. 4 add
10 cc. of hydrochloric acid and pepsin.
4. In a fifth test tube place a lump of egg albumen. Add
10 cc. of hydrochloric acid and pepsin. This is tube No. 5.
Label each tube and keep them all at a temperature of 98° F.
(about 37° C.) for 24 hours. To do this put them in a water
bath in a fireless cooker or in a water oven.
5. In which tube is the egg albumen most completely
liquefied or digested ? To what may some of the cases of
indigestion be due ?
6. Compare tubes No. 4 and No. 5. How is the diges-
tion of proteins affected by insufficient mastication ?
B. Action of the Pancreatic Juice.
The ferment in the pancreatic juice which acts upon pro-
teins is trypsin. It acts in an alkaline solution in the small
intestine.
1. In each of 3 other test tubes place 3 grams of the
minced egg albumen. Number these test tubes No. 6,
No. 7, and No. 8 respectively. To No. 6 add 10 cc. of
pancreatin solution and 10 cc. of the hydrochloric acid.
To No. 7 add 10 cc. of pancreatic and 10 cc. of the sodium
carbonate solution. Put these tubes into the same water
FOOD ANALYSIS 107
bath at 98° F. or 37° C. for 24 hours. To No. 8 add only
pancreatin solution.
2. Note results in Nos. 6, 7, and 8. In which tube is
digestion most complete ?
Questions
1. If you drink a glass of milk, explain all the changes
the casein will undergo before it enters the blood. Tell
where each change takes place, and the name of the ferments
causing it.
2. Of what use are proteins to the body?
3. Explain how fats are digested. (See Appendix.)
4. Of what use are fats to the body ?
5. How are the sugars (disaccharids) digested? (See
Appendix.)
6. Of what use are the sugars to the body ?
7. If you eat ice cream explain completely the digestion
of fat, the cane sugar, and the milk sugar.
XII. FOOD ANALYSIS
It would be impossible in a course of this kind to take up
in detail the analysis of many foods. Milk is the most
common food and possibly the one most subject to adultera-
tion and contamination. Its composition and method of
analysis should be understood.
Books of reference :
1. Olsen, Pure Foods.
2. Leach, Food Inspection and Analysis.
3. Sherman, Food Products.
4. Wing, Milk and Its Products.
5. Woodman, Food Analysis.
108 FOOD ANALYSIS
EXPERIMENT 47
Analysis of Milk
Materials. Whole milk, skimmed milk, dilute hydrochloric
acid, litmus, rennin or junket tablets, Fehling's solution.
Apparatus. Hydrometer, lactometer, hydrometer jars, evaporat-
ing dish, balance, centrifugal machine.
A. Specific Gravity of Milk. (Instructor's Experiment.)
1. Test the specific gravity of water, whole milk, and
skimmed milk with a hydrometer. Which is the heaviest
per unit volume ? Which is the lightest ?
2. Test the specific gravity of water, whole milk, and
skimmed milk with a lactometer. Could water be added
to skimmed milk till its specific gravity was that of whole
milk? Try it.
B. Water in Milk. (Student's Experiment.)
1. Weigh an evaporating dish on a balance. Pour about
20 cc. of whole milk into the dish and weigh again. What
is the weight of the milk? Heat the milk gently until all
the water is evaporated. Do not let it char. Weigh the dish
with the residue. Calculate the per cent of water in milk.
2. Tabulate your data thus :
(a) Weight of empty dish = g.
(6) Weight of dish plus milk before evaporating water = g.
(c) Weight of dish plus residue after evaporating water = g.
(&) — («) = g., weight of milk used
(6) — (c) = g., weight of water in milk
3. Calculate the per cent of water thus :
Weight of water ~ weight of milk
Xl00 = % water in milk.
What is the correct per cent of water in milk?
ANALYSIS OF MILK 109
C. Total Solids in Milk (Albumen, Casein, Lactose, Fats, Mineral
Matter).
1. From the data in B, 2 above calculate the per cent of
total solids in milk, thus :
(6) — (a) = g., weight of milk used
(c) — (a) = g., weight of residue or total solids
Then, weight of total solids -r weight of milk X 100 =
■ % of total solids in milk.
2. What is the correct per cent of solids in milk ?
3. If the per cent of total solids is less than 12%, what
does it indicate ?
D. Mineral Matter in Milk.
1. Ignite the residue that remains after evaporating the
water in (B) until only a white ash remains. What sub-
stances in the residue will burn ?
2 Weigh the dish plus ash and call this (d).
3. Determine the per cent of ash thus :
(6) — (a) = g., weight of milk used
(d) — (a) = g., weight of ash
Weight of ash -s- weight of milk X 100= % of ash
4. What is the correct per cent of ash in milk ?
5. What is the ash in milk chiefly?
E. Fats in Milk. (Instructor's Experiment.)
1. Milk is an emulsion. The small particles of butter
fat are held in suspension by the milk albumen and casein.
If fresh milk is allowed to stand in a cool place, the butter
fat rises, forming a layer of cream. This is the gravity
method of separating cream from milk.
2. In dairies the cream is separated from the milk more
completely and more quickly by the centrifugal cream sepa-
110 FOOD ANALYSIS
rator. Show the principle of the separator by filling the
tubes of a centrifugal machine with whole milk. Operate
the machine for five minutes and note the layer of cream in
the tubes.
3. If there is a Babcock milk-testing machine in the labor-
atory, determine the per cent of butter fat in whole milk.
(See Experiment 48.)
4. What is the usual per cent of fat in milk ?
5. What per cent is required by law in the city ?
F. Albumen in Milk. (Student's Experiment.)
1 . How would you show the presence of albumen in milk ?
Recall Experiment 43, A, 7.
2. What is the per cent of albumen in milk?
G. Casein in Milk.
1. To half a test tube of skimmed milk add dilute hydro-
chloric acid or any dilute acid. Warm. Wrhat is the coagu-
lated mass ? Recall Experiment 43, B, 2.
2. Test milk with litmus. Result? Now let it stand in
a warm place for two or three days till it is thick. Taste
it, smell it, and test with litmus. Some of the lactose is
changed to lactic acid, which coagulates the casein.
3. Warm 50 cc. of milk in your evaporating dish. Add
a little "rennin" or "rennit" or a piece of "junket tablet"
about the size of a pin head. Stir till it is dissolved, then
cool it. Result ? Keep this for H.
4. What is the per cent of casein in milk ?
H. Lactose, the Sugar in Milk.
1. Warm the coagulated casein obtained in G, 3 above,
then filter the "curd." The greenish liquid obtained as
the filtrate is called " whey.:*
BABCOCK TEST FOR BUTTER FAT IN MILK 111
2. Add Fehling's solution to some "whey." Boil. Is
lactose present ?
3. What is the per cent of sugar in milk?
Questions
1. What is the average composition of cow's milk?
2. Is milk a perfect food for an adult ? Why?
3. What is butter?
4. What is buttermilk?
5. What is cottage cheese ?
6. How is the ordinary grocery or "eheddar" cheese
made?
7. What is evaporated milk?
8. What is ice cream?
EXPERIMENT 48
Babcock Test for Butter Fat in Milk
Note : Four varieties of test bottles are used as follows :
a. for whole milk, graduated for 8 % to io %.
b. for ordinary cream, graduated for about 30 %.
c. for whipping cream, graduated for 50 %.
d. for skimmed milk, graduated for .5 %.
Materials. Bottle of whole milk, concentrated sulfuric acid,
skimmed milk, canned milk, ordinary cream, whipping cream.
Apparatus. Babcock test bottles as indicated above, Babcock
tester, pipette.
A. Whole Milk.
1. Thoroughly mix the entire bottle or can of milk by
pouring back and forth into a beaker several times.
2. Using the pipette, measure 17.6 cc. and deliver into the
test bottle a (for whole milk). Incline the test bottle so
112 FOOD ANALYSIS
that the milk will run down one side of the narrow neck while
air passes out the other side, to avoid bubbling and loss of
milk.
3. Add 17.5 cc. of concentrated sulfuric acid, inclining the
test bottle as before and revolving it slowly so that all parts
of the neck have the milk washed down.
4. The acid sinks to the bottom. Mix acid and milk
by revolving and gentle shaking, being careful not to throw
clots back into the neck. The acid dissolves all but the fat
and the contents turn dark brown and get hot.
5. Put the bottle into the Babcock testing machine.
Fill all the pockets with bottles of milk to be tested or fill
the opposite bottles to balance the machine.
6. Whirl 5 minutes at the required speed (80 turns per
minute usually). Add hot water to fill the neck of the test
bottle. Whirl 2 minutes more.
7. Add hot water to drive all the fat into the neck of the
test bottles, but not above the graduations. Whirl one
minute more.
8. Read the per cent of fat from the graduated neck while
still hot. What is the per cent of butter fat in the sample
of whole milk?
B. Ordinary Cream.
1. Put empty test bottle b on the scales. Weigh it. Add
just 18 grams of thoroughly mixed cream. This is about
the amount of cream that the 17.6 cc. pipette will deliver.
9 grams of cream may be used and the result multiplied
by 2.
2. Add acid and proceed as for milk. What is the per
cent of butter fat in ordinary cream ?
BEVERAGES— TEA, COFFEE, COCOA 113
C. Whipping Cream.
1. Put empty test bottle c on the scales and proceed as
for ordinary cream. 9 grams may also be used and the per
cent multiplied by 2. What is the per cent of butter fat in
whipping cream ?
D. Skimmed Milk.
1. Use test bottle d with two necks, the larger to deliver
materials into the smaller, to read the fractions of per cents
as the fat rises. What is the per cent of butter fat in skimmed
milk?
E. Canned Milk.
1. Pour out entire contents of the can and mix well.
2. Weigh 9 grams into test bottle a. Add 9 cc. of water.
Mix thoroughly in the test bottle. Add enough concen-
trated sulfuric acid to turn the contents dark brown. Pro-
ceed as before. '
3. If the canned milk is sweetened special precautions
may be necessary. (See Leach.) What is the per cent of
butter fat in the milk tested ?
EXPERIMENT 49
Beverages — Tea, Coffee, Cocoa
References :
1. Olsen, Pure Food, pages 110-112.
2. Sherman, Food Products, pages 465-466.
3. Bailey, Sanitary and Applied Chemistry, Chapter XXII.
Materials. Tea, coffee, chocolate, cocoa, ferric chloride,
chloroform, iodine solution, sulfuric acid, Fehling's solution,
Millon's reagent.
Apparatus. Beakers, funnels, filter paper, test tubes, graduate,
teaspoons, tablespoons, separatory funnel
114 FOOD ANALYSIS
Tea
A. Tannin in Tea.
1. Boil 50 cc. of water in a beaker. Add a level tea-
spoonful of tea and remove from the flame at once. Allow
it to stand just five minutes, then filter. Place 5 cc. of the
filtrate in a test tube, add 1 cc. of ferric chloride, 25 cc. of
water from your graduate. Stir. Keep this test for com-
parison. What is the dark precipitate?
2. To 50 cc. of boiling water in the beaker add a level
teaspoonful of the same tea and boil for five minutes, then
filter. Place 5 cc. of the filtrate in a test tube of the same
size as that used in A, 1. x\dd 1 cc. of ferric chloride solu-
tion and then 25 cc. of water. Stir. Compare the intensity
of color with that of A, 1 and explain. What is the best
method of preparing tea ? Why ?
B. Theine or Caffeine in Tea. (Instructor's Experiment.)
1. Boil three teaspoonfuls of good tea in 100 cc. of water
for five minutes, filter, cool, and add 20 cc. of chloroform.
Place the mixture in a separatory funnel, shake well for one
minute, and then allow the chloroform to settle. Draw it
off into a clean beaker and allow it to evaporate at room
temperature. Note the pleasant smelling, silky crystals
of theine or caffeine. (They are the same chemically.)
C. Questions on Tea.
1. How is green tea prepared for market? Name some
varieties of green tea on the market.
2. How does black tea differ from green tea ? Name some
varieties of black tea on the market.
3. Which contains more tannin, the black or the green
tea ? Give the reason for vour answer.
BEVERAGES— TEA, COFFEE, COCOA 115
Coffee
D. Tannin in Coffee.
1. To 200 cc. of cold water in your large beaker add one
tablespoonful of well-ground coffee. Slowly bring this to
the boiling point and boil for three minutes. Filter. Treat
5 cc. of the filtrate as in A, 1. Keep the test for comparison.
2. Repeat D, 1, but boil for fifteen minutes. Filter and
treat 5 cc. of the filtrate as in A, 1. Compare the intensity
of color with that of D, 1 and explain. What is the best
method of preparing coffee? Why?
E. Caffeine or Theine in Coffee. (Instructor's Experiment.)
1. Add two tablespoonfuls of coffee to 250 cc. of cold
water. Bring slowly to the boiling point and boil five min-
utes. Filter. Cool the filtrate and repeat B, 1. Note
the pleasant smelling, silky crystals of caffeine or theine.
What is the effect of caffeine or theine upon the human
system ?
F. Questions on Coffee.
1. How is coffee prepared for market?
2. Why is the coffee bean roasted?
Chocolate and Cocoa
G. Fat in Chocolate and Cocoa.
1. Test both chocolate and cocoa for fat by treating 10
grams of each with 50 cc. of gasoline. Shake well and filter
through a dry filter. Allow the gasoline to evaporate.
Which contains the most fat?
H. Questions on Chocolate and Cocoa.
1. How is chocolate prepared from the bean for market?
2. How is the beverage made from chocolate?
116 FOOD ADULTERANTS
3. How does the preparation of cocoa on the market
differ from that of chocolate?
4. Which beverage is the more nourishing, chocolate or
cocoa ? Why ?
5. For what other purposes are chocolate and cocoa used?
Note: If possible visit a manufacturing house where chocolate and cocoa
are prepared from the unroasted beans.
XIII. FOOD ADULTERANTS
The most important food adulterants may be divided
into three classes : (1) Substitutes. (2) Artificial Coloring.
(3) Preservatives.
References :
1. Leach, Food Inspection and Analysis.
2. E. M. Bruce, Detection of the Common Food Adulterants.
3. Woodman, Food Analysis.
4. Olsen, Pure Foods.
EXPERIMENT 50
Adulterants in Milk
Materials. Milk containing borax or boric acid, another sample
containing formaldehyde, limewater, hydrochloric acid, turmeric
paper, ferric ammonium alum, concentrated sulfuric acid.
Apparatus. Evaporating dish, test tubes.
A. Substitutes.
1. Cream may be removed and water added until the
specific gravity is that of pure whole milk. What should
be the per cent of water in whole milk? How can the per
cent of water in milk be determined? (See Experiment 47.)
ADULTERANTS IN MILK 117
B. Artificial Coloring.
Milk is seldom colored artificially. Annatto or turmeric
might be used as in the case of butter and they would be
detected in the same way.
C. Preservatives.
1 . Borax and boric acid in milk may be detected as follows :
Place 20 cc. of milk in an evaporating dish. Add 5 cc. of
limewater. Evaporate to dryness. Continue to heat the
dish till only a white residue remains. If borax or boric
acid was in the milk it will be present in this ash. Dissolve
the residue in 1 cc. of dilute hydrochloric acid. Dip a strip
of turmeric paper in the solution and dry at 100° on a test
tube of boiling water. A bright red color indicates the
presence of boric acid or borax. The red color is changed
to dark green by a drop of ammonium hydroxide.
If there is much borax or boric acid present, the test may
be simplified. Acidify the milk with hydrochloric acid.
Dip in the turmeric strip. Dry at 100° on a test tube of
boiling water. A bright red color will appear.
2. Formaldehyde in milk may be detected as follows :
Dissolve a crystal of ferric ammonium alum (about the
size of a pea) in about 1 cc. of "water. Carefully add
1 cc. of concentrated sulfuric acid. Pour this solution
carefully down the side of an inclined test tube contain-
ing about 10 cc. of the milk to be tested. A violet colora-
tion is produced at the junction of the two liquids if
formaldehyde is present. Warm over the Bunsen burner
if necessary.
If possible visit a large dairy or creamery and note par-
ticularly the precautions taken for the sake of cleanliness.
118 FOOD ADULTERANTS
EXPERIMENT 51
Test for Adulterants in Butter
Materials. Pure butter, oleomargarine, ice water, sweet milk,
carbon disulfide, ethyl alcohol, hydrochloric acid, ammonium
hydroxide, concentrated sulfuric acid, white woolen yarn, tur-
meric paper.
Apparatus. Test tubes, beakers, pine splints.
A. Detection of Substitutes.
1 . In two separate test tubes place 5 grams of pure butter
and 5 grams of oleomargarine or renovated butter. Heat
each over the Bunsen burner. The pure butter melts
quietly, producing much foam, while the renovated butter
or oleomargarine sputters and crackles and produces very
little foam. This is called the foam test for butter.
2. In two separate small beakers place 5 grams of pure
butter and of oleomargarine. Add to each about 25 cc. of
sweet milk and warm gently till the samples are melted. Then
place the beakers in ice water and stir constantly with pine
splints till the fat solidifies. In the case of oleomargarine
the fat will collect in a lump which may be lifted out by the
stick, while pure butter or renovated butter will form an
emulsion with the milk resembling cream.
3. Given an unknown sample, how would you proceed
to determine whether it was oleomargarine, renovated but-
ter, or real butter ?
B. Detection of Artificial Coloring in Butter.
1. To 5 grams of butter in a large test tube add 4 grams
of carbon disulfide and 30 grams of ethyl alcohol. Shake
well and allow the mixture to stand till it separates into
TEST FOR ADULTERANTS IN BUTTER 119
two layers. The lower layer is the carbon disulfide contain-
ing the butter fat in solution. The upper layer is alcohol,
which dissolves the dye and is colored by it. If the alcohol
layer is colorless, the butter contains no artificial coloring.
If the alcohol layer is colored, test for artificial dyes as
follows :
2. Turmeric : To 5 cc. of the alcohol layer add ammonium
hydroxide. If a brown color is produced, turmeric was used
to color the butter.
3. Annatto : Evaporate 10 cc. of the alcohol layer to
dryness with a low Bunsen flame. Add a drop of concen-
trated H2S04 to the residue. A greenish blue coloration
indicates the presence of annatto.
4. Coal-tar dyes : To 10 cc. of the alcohol extract add 10
cc. of water. Add 1 cc. of HO and a piece of white woolen
yarn. Boil. If the yarn is colored the presence of coal-tar
dyes is shown.
C. Preservatives in Butter.
1. The preservative most often used is boric acid. To 10
grams of butter add 10 cc. of water and boil. Pour off the
melted fat. To the water remaining add 1 cc. of HC1. Dip
a strip of turmeric paper into the solution and dry on a test
tube of boiling water. A cherry red color denotes the pres-
ence of boric acid. Add a drop of ammonia to the colored
paper. Result ?
Questions
1 . How is pure butter made ?
2. What is "renovated butter"?
3. What is oleomargarine ?
120 FOOD ADULTERANTS
EXPERIMENT 52
Adulterants in Jellies and Candies
Materials. Jellies, candies, iodine solution, acid mercuric ni-
trate (see Appendix), picric acid solution, AN hydrochloric
acid, white woolen yarn or strips of white woolen cloth.
Apparatus. Test tubes, beakers.
A. Substitutes.
1 . Starch : Boil about 5 grams of jelly with water, cool, and
add a solution of iodine. The usual dark blue color indicates
the presence of starch.
Test cheap candies for starch.
2. Gelatin: Put 1 cc. of jelly in a test tube. Add 10 cc.
of water. Warm till the jelly is dissolved. Cool. Add
an equal volume of acid mercuric nitrate and 20 cc. of cold
water. Shake well and allow it to stand for five minutes.
Filter. If gelatin is present the filtrate will be cloudy.
To confirm the test add 1 cc. of saturated water solution of
picric acid to a portion of the filtrate. If gelatin is present,
a yellow precipitate will be formed. Test candy in the same
way.
B. Artificial Coloring.
Artificial jams and jellies are often colored with anilin
dyes to imitate the natural fruit product, therefore a test for
the dyes indicates the character of the product.
1. Dissolve about 15 grams of the jelly in 100 cc. of water.
Filter if necessary. Add 1 cc. of 4 N hydrochloric acid. Place
in it strips of white woolen cloth or woolen yarn and boil
for five minutes. Now remove the strips and wash them in
cold water and then boil again in a very dilute solution of
hydrochloric acid. If the strip has a dull color the coloring
ADULTERANTS IN JELLIES AND CANDIES 121
matter in the jelly was due to the natural coloring in the fruit.
If the strip is brightly colored, anilin dyes were present.
Paste the strip in the notebook.
2. In like manner test candies for the presence of anilin
dyes. Paste the strip in the notebook.
C. Preservatives.
1 . Candies and jellies are naturally preserved by the sugar
present.
2. By what four methods may foods be preserved?
3. Describe briefly each method.
4. Which methods are harmless ?
5. Which are not? Why?
6. How are pure jellies prepared ?
7. How are pure candies prepared ?
XIV. FOOD VALUES
Food is any substance which when taken into the body
supplies it with heat and energy or builds tissue.
There are five classes of food principles : proteins, fats, car-
bohydrates, mineral matter, and water. Proteins, mineral
matter, and water are the tissue builders. Fats and carbo-
hydrates furnish heat and energy. Proteins, fats, and carbo-
hydrates are called the nutritive constituents of foods.
These nutritive constituents oxidize or burn in the body
and produce heat. The amount of heat so produced has
been found to be the same as the heat produced by the
substances if burned outside the body in the laboratory.
When burned in the laboratory the heat produced is meas-
ured in calories. A calorie is the amount of heat necessary
to raise a kilogram of water 1° C. (large calorie).
122
FOOD VALUES
In the back of this Manual, you will find approximately
the food value in calories necessary for a girl (woman) of
your weight. There are also tables showing the portion of
ordinary foods that contain 100 calories of heat.
EXPERIMENT 53
Menu Making
A. Daily Menu.
1. From the Appendix find the calories (food units) re-
quired for your weight, calories furnished by protein, fat, and
carbohydrate.
2. One fourth of this amount should be furnished by the
breakfast, one fourth by the lunch, and one half by the dinner.
3. Now prepare a menu for a day for yourself, using the
following as a model :
Daily Menu
Weight 159 lb. requires 239 calories protein, 717 calories
fat, 1434 calories carbohydrate, total 2390 calories, J for
breakfast, \ for lunch, \ for dinner.
Meals
Calories
Protein
Calories
Fat
Calories
Carbohydrates
Total
Calories
Breakfast
Lunch
Dinner
Total calories
61
58
120
239
176
175
350
701
350
360
725
1435
587
593
1195
2375
B. Dinner Menu.
1. Make a dinner menu giving careful attention (a) to
the correct number of calories as found in A, and (b) to
the current market prices of foods, making the total cost of
the dinner as low as possible. Tabulate as follows :
PRODUCTS OF YEAST FERMENTATION
Dinner Menu
123
Food
Portion
Ounces
Cost
Calories
Protein
Calories
Fat
Calories
Carbohy-
drate
Lamb, leg,
roasted,
etc.
Total
Ord. serving
1.8
.05
40
60
00
XV. LEAVENING AGENTS
A leavening agent is a substance which, when put into a
dough, usually forms carbon dioxide. This gas "lightens"
the dough.
Yeast is the oldest leavening agent. It changes starch
and sugar to carbon dioxide and alcohol.
Baking soda is sodium bicarbonate, NaHC03. It may be
used in dough with some substance that contains an acid,
such as sour milk or molasses. Baking powder is a mixture
of powdered sodium bicarbonate with a powdered acid or
acid principle, such as tartaric acid or an alum, with starch to
keep the mixture dry.
EXPERIMENT 54
Products of Yeast Fermentation
Materials. Yeast cake (compressed), molasses, limewater.
Apparatus. 250 cc. flasks, test tube, delivery tube, distilling
flask, condenser, thermometer, liter beaker.
A. Carbon Dioxide.
Note : Two students work together.
1. Mix about one fourth of a cake of compressed yeast
with 15 cc. of water in the evaporating dish. Stir till a
124 LEAVENING' AGENTS
smooth mixture is formed. Pour the yeast mixture into a
flask containing 25 cc. of molasses and 100 cc. of water.
2. Note the odor and taste of the mixture.
3. Fit a one-holed stopper and a delivery tube to the flask
containing the mixture. Let the other end of the delivery
tube dip into a flask containing limewater.
4. Put the flasks in the sun or a warm place.
Begin Experiment 55.
5. At the end of two hours examine the liquid and lime-
water. Is the yeast working ? What gas caused the change
in the limewater? Write the equations and name all sub-
C02+Ca(OH)2 — ^ CaC03+H20
6. What effect has a very low temperature upon fermen-
tation ? Why are fresh vegetables, fruits, milk, and butter
kept in a refrigerator ?
7. Boil 10 cc. of the fermenting yeast mixture. Cool
again to room temperature. Does fermentation continue?
Why? Why do jars of canned fruit sometimes ferment?
If these fruits are reheated soon after fermentation begins,
they may be used. Why ?
B. Alcohol.
1. At the end of 12 hours examine the mixture. Has
fermentation ceased ? Why ?
2. Note the odor and taste of the mixture. What new
substance is present ? The sugar in the molasses is changed
to alcohol and carbon dioxide. Write the equation and
name all substances.
C6H1206+yeast— ^2 C2H5OH+2 C02
BAKING SODA, BAKING POWDER 125
Note : Empty the mixture in your flask into the liter beaker provided. The
teacher will distill half of this for alcohol, the other half should be labeled
and set aside for a week or more for part C.
3. (Instructor's experiment) :
Distill about 500 cc. of the fermented molasses, using a
water bath. Collect the fraction that comes over below
79° C. What is this distillate chiefly?
4. Note the odor of the distillate.
5. Apply a lighted match to 1 cc. of it. Does it burn?
6. What is formed when fruit juices containing sugar
ferment? Where does the yeast that causes the fermenta-
tion come from ?
7. How does yeast leaven bread dough ?
C. Vinegar.
1. Note the odor and taste of the yeast molasses mixture
that has been allowed to stand for several weeks. What is
the substance ?
2. How could vinegar be made at home from fruit parings ?
3. What is "sweet cider"?
What is "hard cider"?
What is "cider vinegar"?
EXPERIMENT 55
Baking Soda, Baking Powder
Materials. Dilute hydrochloric acid, sulfuric acid, sodium bi-
carbonate, molasses, sour milk, powdered tartaric acid, cream
of tartar, acid calcium phosphate H4Ca(P04)2, ammonium
alum, any baking powder (composition unknown to student),
6 common baking powders with labels, iodine solution, barium
chloride solution, ammonium molybdate solution.
Apparatus. Test tubes, beakers, funnel, filter paper.
126 LEAVENING AGENTS
A. Baking Soda (Sodium Bicarbonate, NaHC03).
1. Put 15 cc. of dilute hydrochloric acid in a beaker.
Add 1 gram of sodium bicarbonate. What gas is evolved?
Write the equation, naming all substances :
HCl+HNaCOs — >- NaCl+C02+H20
2. Dissolve 5 cc. of molasses in 15 cc. of water in a beaker.
Add 1 gram of sodium bicarbonate. Result? What is the
acid in molasses?
3. Repeat (2), using sour milk. Result? What is the
acid in sour milk ?
4. How is "soda" used to leaven a dough?
B. Baking Powders.
1. Tartrate baking poivders.
a. Make a tartrate baking powder by mixing a gram of
tartaric acid (H2C4H4O6) with a gram of sodium bicarbonate
(NaHC03). Add 15 cc. of water. Result? What is the
gas evolved ? Write the reaction and name all substances :
H2C4H406+2 NaHC03 — >- Na3C4H406+2 H20+2 C02
b. Make a tartrate baking powder by mixing cream of
tartar (acid potassium tartrate, HKC4H406) with the soda.
Add water as before. Result? Write the equation and
name all substances :
HKC4H406+HNaC03 — ^ KNaC4H406+H20+C02
2. Phosphate baking powders.
Repeat B, 1, using acid calcium phosphate, H4Ca(P04)2,
with the soda. Write the equation and name all substances :
H4Ca(P04)2+2 HNaC03 — ^
HNa2P04+HCaP04+2 H20+2 C02
BAKING SODA, BAKING POWDER 127
3. Alum baking powders.
Repeat B, 1, using, instead, powdered ammonium alum,
NH4A1(S04)2, with the soda. Write the equation and name
all substances :
2 NH4Al(S04)2+6 HNaC03 — >-
2 Al(OH)3+(NH4)2S04+3 Na2S04+6 C02
4. Why is baking powder such a useful leavening agent?
5. Which baking powder is considered most efficient of the
three mentioned? Why?
C. Tests for Baking Powders.
A baking powder may be a tartrate baking powder, or
an alum powder or a phosphate powder or a mixture of two
or three of these powders. Test an unknown baking powder
to determine its nature as follows :
1. Put 15 grams of the baking powder into a beaker and
pour over it 50 cc. of water. Stir until no more gas is
evolved, then filter carefully.
2. Starch is insoluble in cold water and will remain on the
filter paper as a white residue. Make the usual starch test
on this residue. Result?
3. If the baking powder contains alum, the filtrate will
contain sulfates. To 5 cc. of the filtrate add 5 cc. of hydro-
chloric acid and 5 cc. of barium chloride solution. A white
precipitate indicates sulfates. Is the sample an alum
baking powder ?
4. If the baking powder is a phosphate baking powder,
the filtrate will contain acid calcium phosphate. Test 5 cc.
of the filtrate for a phosphate by adding a few drops of nitric
acid, then heat nearly to boiling and add a few drops of this
hot mixture to 5 cc. of ammonium molybdate solution. A
128 TEXTILES
yellow precipitate shows the presence of phosphates. Is the
sample a phosphate baking powder ?
5. To test for a tartrate baking powder, pour 5 cc. of the
filtrate into an evaporating dish- Add 5 drops of sulfuric
acid and evaporate to dryness. Heat gently and note the
odor of burning sugar if a tartrate is present. Is the sample
a tartrate baking powder ?
6. Examine labels of 6 different baking powders on the
market and note the ingredients of each.
XVI. TEXTILES
The chief fibers of vegetable origin are cotton and linen.
The important fibers of animal origin are wool and silk.
Reference :
1. Woolman and McGowan, Textiles.
EXPERIMENT 56
Cotton, Linen, Wool, and Silk
Materials. Cotton, linen, wool, and silk textiles, 5% solution of
KOH, concentrated HC1, Loewe's solution.
Apparatus. Microscope, forceps.
A. Microscopic Tests.
1. Examine raveled samples of cotton, linen, wool, and silk
fibers under the microscope. Draw each fiber and label it.
B. Burning Test.
1 . Hold a strip of wool with the forceps and ignite it in the
Bunsen flame. Note the odor and appearance as it burns.
2. Repeat, using strips of silk, cotton, and linen. Note
COTTON, LINEN, WOOL, AND SILK
129
the odor and appearance of each as they burn. Which of
the fibers may be detected by its odor in burning ?
C. To Distinguish Silk and Wool from Cotton and Linen.
1. Boil about one square inch of woolen textile in a beaker
containing 10 cc. of a 5% solution of KOH. Result?
2. Repeat (1), using silk, cotton, and linen in separate
beakers. Note results in each case.
3. Many so-called woolen textiles contain cotton. To
detect the presence of cotton cut two samples of the material
2 by 2 inches ; mount the first one. Boil the second sample
for 10 minutes with a 5% solution of KOH. If the wool is
pure, there will be no residue. If a residue is left, mount it,
and explain the result. Record results as follows :
Sample of wool
used for experi-
ment.
Sample of same
material boiled
10 minutes in
5% KOH.
D. To Distinguish Wool from Silk.
1. In a beaker containing 20 cc. of concentrated HC1
place a strip of wool and one of silk and boil for two
minutes. Which is dissolved ?
2. Cut 2 samples of material supposed to be a mixture of
wool and silk. Mount one sample. Treat the other as in 1.
Pure silk will dissolve in concentrated hydrochloric acid.
If it is weighted, a residue remains. If wool is present,
the fibers will be undissolved. Wash, dry, and mount the
sample, unless it is entirely dissolved.
130 TEXTILES
Sample of ma-
terial used.
Sample in con-
centrated HC1
for 2 minutes.
a b
E. To Distinguish Cotton from Silk.
1. In a beaker containing 20 cc. of Loewe's Reagent place
a strip of cotton and one of silk. Which fibers dissolve ?
2. Artificial silks are usually cellulose. How would you
distinguish real silk from artificial silk ?
DYEING
When a* colored substance is attached to the fibers of the
textile in such a way that it is not removed by rubbing or
washing or by the sunlight, the textile is dyed.
Several of the metallic hydroxides are used as mordants
in dyeing. They form insoluble precipitates, called lakes,
with dyes. Wlien these lakes are formed in the fibers of the
textile, the dye is fixed and the colors are fast.
A dye that will dye textiles without the use of a mordant
is called a direct dye. A dye that will not dye textiles with-
out the use of a mordant is called a mordanted dye.
Reference : Woolman and McGowan, Textiles.
EXPERIMENT 57
Textile Dyeing
Materials. Dilute ammonium hydroxide, aluminum sulfate,
5% logwood solution (see Appendix), alizarin, strips of cotton
cloth 1 inch by 3 inches from which sizing has been removed
by boiling in a 2 % solution of sodium carbonate for 5 minutes,
Congo red solution prepared by dissolving in 200 cc. distilled
TEXTILE DYEING 131
water, 1 g. sodium carbonate, 2 g. sodium sulfate, and 2 g.
Congo red.
Apparatus. Test tubes, enameled pans or beakers for the color
baths.
A. Mordants and Lakes.
1. Add 5 cc. of dilute ammonium hydroxide to 10 cc. of
aluminum sulfate solution. The gelatinous precipitate is
aluminum hydroxide. Write the equation for the reaction.
Add 2 cc. of logwood solution. Shake the tube well and let
it stand. Is the dye held by the precipitate? This colored
precipitate is called a lake. The aluminum sulfate is a mor-
dant.
2. Repeat A, 1, using 2 cc. of alizarin instead of the log-
wood solution. Let the tube stand. Result?
B. Use of Mordants in Dyeing.
1. Boil in a logwood solution for five minutes a strip of
cotton cloth from which the sizing has been removed. Re-
move, wring, and wash thoroughly. Does the color wash
out? Dry the strip and mount it in your notebook.
2. Mordant a piece of cotton cloth by boiling it in 20 cc.
of aluminum sulfate solution. Wring out and let it stand
in warm, dilute ammonium hydroxide for five minutes.
Wring it out.
Now boil this mordanted strip in a logwood solution for
five minutes. Wring out and wash thoroughly. Does the
color wash out ?
Paste the strip in your notebook.
3. Repeat B, 1, using an unmordanted (wet) strip in
alizarin. Wash, dry, and mount in your notebook.
4. Repeat 3, using a mordanted strip (wet) prepared
as in B, 2, and alizarin. Paste the strip in your notebook.
132 TEXTILES
C. Direct Dye for Cotton.
1. Place a wet piece of cotton cloth (unsized) in 20 cc. of
prepared Congo red solution and boil 5 minutes. Remove
the cloth, wash, dry, and mount it in your notebook.
CLEANING OF FABRICS
Many useful books are now on the market that explain in
detail the removal of spots and stains from fabrics. A few
principles of stain removing will be outlined.
Reference : Woolman and McGowan, Textiles.
EXPERIMENT 58
Removing Spots and Stains
Materials. Strips 3 inches by 4 inches of white cotton cloth
stained with (a) blood, (b) another set of strips stained with
coffee, (c) with spots of fruit juice, (d) with chocolate, (e) with
grease, (/) with paint, (g) vaseline, (/?) ink stains; hydrogen
peroxide, ammonium hydroxide, Javelle water (see Appendix),
borax, gasoline, carbon tetrachloride, absorbent cotton or
blotters, soap, turpentine, bleaching powder, dilute hydrochloric
acid, oxalic acid, Ink Eradicator (see Appendix).
Apparatus. Beakers.
A. Stains Removed by Cold Water.
For blood and stains of a protein nature, also for unknown
stains, use cold water. The cloth is placed over a bowl or
some convenient vessel and water poured first around the
stain, then on it.
1. Remove a blood stain by this method, or if the
stain is old, lukewarm water and soap will remove it more
quickly.
REMOVING SPOTS AND STAINS 133
B. Stains Removed by Hot Water.
Hot water is used for colors held in a sugary solution and
for glue. Sometimes if the stain is old, a bleach or some sub-
stance that will react with the coloring matter should be used
with the hot water.
1 . Remove a coffee stain by putting the spot over a beaker
and then pour boiling water first around the spot, then on it.
If it is not removed, try hydrogen peroxide, alkaline with am-
monia, on the spot ; then add hot water. Or soak in weak
Javelle water for a few minutes and rinse with boiling water.
2. Remove a, fruit stain by the method of B, 1.
3. Remove a chocolate or cocoa stain by covering stain with
borax. Soak in cold water, then pour on hot water.
C. Stains Removed by Solvents.
Spots produced by grease, vaseline or waxes, paint, varnish,
or tar cannot be removed by water. Grease and waxes are
soluble in chloroform, carbon tetrachloride, ether, gasoline,
or benzene. Paint, varnish, or tar should be treated with
turpentine, then with one of the solvents above.
1. Remove a grease spot by carbon tetrachloride. Place
absorbent cotton or a blotter under the spot and rub the sol-
vent from the outside toward the center of the spot. Follow
with warm soap and water.
2. Remove a paint stain by using turpentine, then gasoline
or carbon tetrachloride.
3. Remove vaseline by soaking in kerosene first, then wash
with soap and water.
D. Stains Removed by Chemical Treatment.
Such stains as iron rust, ink, acid stains, grass stains, and
mildew need a special bleach or other chemical treatment.
134
TEXTILES
1. Remove an ink stain, if fresh, by cold water. Or apply
alternately solutions of bleaching powder and dilute hydro-
chloric acid or oxalic acid. Or apply Javelle water or ink
eradicator prepared.
E. For the removal of other stains see the following table :
Kind of Stain
Fruit, tea, or coffee
Reagent Used
1. Boiling water, if stain is fresh. If
old, use bleaching powder and a
little acetic acid or hydrogen per-
oxide and hot water.
2. Javelle water.
1. Alcohol or ammonia.
2. Javelle water.
j'l. Gasoline. f Follow with
Grease <j 2. Carbon tetrachloride I soapsuds and
[ [ammonia.
Grass
Vaseline
Tar
Paint
Varnish
Acids, hydrochloric, sulfuric
Iron rust
Kerosene ; follow with warm soap
solution.
f 1. Benzol.
2. Turpentine ; follow with soap and
ammonia.
f 1. Carbon tetrachloride.
2. Turpentine; follow with soap and
ammonia.
/ Equal parts of wood alcohol, benzol,
\ and acetone.
Ammonia in each case.
f 1. Oxalic acid. Afterwards wash out
acid with hot water.
Salt and lemon juice, or citric acid.
Ink
Iodine
12-
fl-
I2'
13.
u.
(i
Sweet milk on colored goods.
Salt and citric acid.
Oxalic acid.
Ink eradicator or Javelle water.
Alcohol.
Sodium thiosulfate.
BLEACHING AND BLUEING 135
Kind of Stain Reagent Used
lyj-, , /Soapsuds. Tartaric acid followed by
\ Javelle water. Sunlight.
T5i i J Wash with cold or lukewarm water
\ and soap.
Sugar, glue Wash with hot water.
EXPERIMENT 59
Bleaching and Blueing
Materials. Strips of colored calico, 3 inches by 1 inch, fresh
bleaching powder, dilute hydrochloric acid 10%, sodium thio-
sulfate solution, sodium sulfite, strips of colored woolen cloth,
3 inches by 1 inch, colored feathers or ecru silk strips, 3 inches
by 1 inch, aniline blue, oxalic acid solution 10%, sodium hy-
droxide solution, Prussian blue, Ultramarine, Indigo.
Apparatus. Beakers, 300 cc. bottle v/ith cork to fit.
A. To Bleach Cotton or Linen.
1. Obtain 2 strips of colored calico. Keep one to mount
later and put the other in a beaker containing a thin paste
of 5 grams of fresh bleaching powder (calcium hypochlorite)
and 100 cc. of water. Remove the strip and dip it into a
beaker containing 25 cc. of hydrochloric acid. Dip the strip
into the bleaching powder again, and again into the acid till
it is bleached.
2. The acid liberates the chlorine from the bleaching
powder. Write the equation. The chlorine bleaches cotton
or linen, but it yellows wool or silk. Dip the strip into a 5%
solution of sodium thiosulfate, which destroys the chlorine
remaining on the cloth and prevents the fiber from being
weakened. Wash the strip, dry it, and mount it in your note-
book with the unbleached sample.
136 TEXTILES
3. Javelle water is often used for bleaching cotton or linen
at home. It is a solution of sodium hypochlorite (NaOCl)
and its bleaching action is similar to that of bleaching
powder.
B. To Bleach Wool or Straw.
1. Put 5 grams of sodium sulfite (Na2S03) in a 300-cc.
bottle and fit it loosely with a stopper. Hang a strip of
colored woolen cloth so that it is suspended in the bottle
when the stopper is inserted. Add 25 cc. of dilute hydro-
chloric acid to the bottle, insert the stopper loosely, and let
it stand. The gas liberated is sulfur dioxide. Write the
equation. Sulfur dioxide bleaches cotton, straw, or silk as
well as wool. Mount an unbleached and a bleached sample
of the woolen cloth in your notebook.
C. To Bleach Feathers, Hair, or Silk.
1. To 10 cc. of hydrogen peroxide in a beaker add am-
monium hydroxide little by little till bubbles of oxygen begin
to form. Immerse a piece of ecru silk or a colored feather.
Leave them till they are bleached.
2. Mount the bleached and the unbleached sample.
D. Blueing.
In addition to bleaching, yellowish goods may be given
a white appearance by "blueing." There are two classes
of blueings: (1) Liquid blueings or those apparently sol-
uble in water and sold in bottles, i.e. anilin blues and Prus-
sian blue. (2) Solid blueings or those insoluble in water,
i.e. ultramarine and indigo.
1. Liquid blueing — Anilin blue.
Obtain 10 cc. of anilin blue. To half of it add 5 cc. of
BLEACHING AND BLUEING 137
oxalic acid solution. The intensity of the blue color is deep-
ened. This acid is sometimes used in the laundry. What
harm does it do to textiles ? Add 5 cc. of sodium hydroxide
to the other half. It usually turns red. What danger is
there in leaving soap in the goods? The anilin blueing is
cheap and satisfactory if used with care.
2. Liquid blueing — Prussian blue.
Obtain 10 cc. of Prussian blue. Add 10 cc. of dilute sodium
hydroxide. The red or yellow precipitate is ferric hydroxide,
which is iron rust. If soap or soda were in the clothes to
be "blued" with Prussian blue, what would probably be the
result ?
3. Solid blueing — Ultramarine.
Usually comes in balls. Obtain a portion of a ball and stir
it in water. It is insoluble in water, but is so finely divided
that if carefully used does not streak the goods. It is not
affected by soap or soda.
4. Solid blueing — Indigo.
Usually in balls. It is expensive. It is insoluble and
apt to streak the goods unless used carefully. It is not af-
fected by soap or soda or light. Obtain some indigo and put
a little into some water. Note the intense blue color.
SOAP
Ordinary hard soap is usually a mixture of the sodium
salts of several organic acids, one of which is stearic acid,
C17H35COOH. The soap sodium stearate would then have the
formula Ci7H35COONa. Soaps are made by the action of
sodium or potassium hydroxide on fats. Fats are solid esters
formed by the action of the alcohol glycerin C3H5(OH)3 on
138 TEXTILES
several organic acids, one of which is stearic acid. The fat
glyceryl stearate is (Ci7H35COO)3C3H5.
Reference : Any organic chemistry or any elementary
chemistry. See also page 155 of the Appendix.
EXPERIMENT 60
Soaps, Cleansing Powders
Materials. Cottonseed oil, alcohol, 40 % solutions of sodium
hydroxide, alcoholic solution of phenolphthalein, toilet soap,
laundry soap, solution of castile soap, calcium chloride solu-
tions, Sapolio or other scouring soap, Dutch Cleanser or other
cleansing powder.
Apparatus. 500-cc. flask fitted with a one-hole rubber stopper
and a straight glass tube 1 yard long, large evaporating dish,
test tubes, beakers, funnel, filter paper.
A. Preparation of Soap. (Instructor's Experiment.)
1. Pour 50 cc. of cottonseed oil into a 500-cc. flask. Add
100 cc. of alcohol and 15 cc. of a 40% solution of sodium hy-
droxide. Place the stopper with the long glass tube (reflux
air condenser) in the flask, and heat for an hour or more.
The alcohol condenses in the tube and runs back into the
flask. Alcohol is not needed to make soap but it dissolves
both the oil and the hydroxide and so causes the action be-
tween them to be more rapid.
2. Pour the mixture into a large evaporating dish or
enamel pan and heat till the alcohol is driven off. Stir con-
stantly. Cool the mixture. The solid substance is soap.
Write the equation for the making of soap. Name all sub-
stances :
(C17H35COO)3C3H5+3 NaOH
— >■ C3H5(OH)3+3 C17H35COONa
SOAP, CLEANSING POWDERS 139
3. Shake some of this prepared soap with distilled water.
Does it produce suds ?
B. Properties of Soap. (Student's Experiments.)
1. Free alkali in soap.
Cut a piece of dry toilet soap and add to the freshly cut
surface a few drops of an alcoholic solution of phenol-
phthalein without water. If a red color appears, free alkali
is present. In the same way test a piece of laundry soap
for free alkali. Why should woolen goods not be washed
with a soap containing free alkali ?
2. Free fat in soap.
Shake a few shavings of dry soap in a test tube with 20 cc.
of gasoline. Filter into a beaker. Allow the gasoline to
evaporate. A greasy residue indicates unsaponified fat.
3. Water in soap.
Place a few shavings of a fresh soap in a large test tube.
Heat the tube gently and look for drops of water on cool
sides of tubes. Result? Is it wise to buy a cheap, soft,
highly scented or colored soap ? Why ?
4. Action of soap in hard water.
If soap is added to a solution of a calcium or magnesium
salt, an insoluble calcium or magnesium soap is formed.
Hard water contains salts of calcium and magnesium and such
waters form a curdy precipitate when soap is added.
To 20 cc. of distilled water add 5 cc. of a pure castile soap
solution. Shake and note the suds. Now add 5 cc. of a
solution of calcium chloride. What is the white precipi-
tate? Shake. Are suds formed?
Write the equation and name all substances :
2 C17H35COONa+CaCl2 — ^ 2 NaCl+(Ci7H35COO)2Ca
140 TEXTILES
C. Water Softeners.
1. When may water be made "soft" by boiling? Ex-
plain. Write equation.
2. Washing soda, Na^CC^, will precipitate calcium or
magnesium salts in hard water as carbonates, thus removing
the "hardness." Write equations to show.
Test a soap powder for sodium carbonate by adding hydro-
chloric acid to 5 grams in a test tube and observe efferves-
cence. Result? Test also a hard water soap. Result?
Note : There are many water softeners on the market ; sodium carbonate,
sodium phosphate, or sodium silicate are often the chief constituents. The
action of these is to precipitate the calcium or magnesium salts as insoluble
carbonates, phosphates, or silicates.
D. Scouring Soaps and Cleansing Powders.
1. Boil 10 grams of a scouring soap, such as Sapolio, or
a cleansing powder such as Dutch Cleanser, in a beaker with
50 cc. of water. Filter.
2. Add dilute hydrochloric acid to the residue. If it
effervesces, insoluble carbonates are indicated. Result?
3. The residue insoluble in dilute acid may be clay, fine
sand, or pumice. Note your sample.
4. Add dilute hydrochloric acid to the filtrate. Efferves-
cence indicates sodium carbonate. Result?
APPENDIX
THE METRIC SYSTEM
This is the system used by scientists. It is used by everyone
in most of the countries of Europe and, because of its con-
venience, is being used more and more in the United States
and Great Britain.
1. Length :
The unit is the meter. It is equal to 39.37 inches or 1.1 yards.
The centimeter is the unit of length most used by the chemist.
It is y^-q- of a meter, or f of an inch.
10 millimeters (mm.) = l centimeter (cm.)
10 centimeters =1 decimeter (dm.)
10 decimeters = 1 meter (m.)
1000 meters =1 kilometer (km.)
2. Volume:
The unit used by the chemist is either the cubic centimeter or
the liter. The volume of a flask may be given as 500 cc. or
\ liter. One U. S. liquid quart = 946.36 cubic centimeters, a
little less than a liter.
1000 cubic millimeters =1 cubic centimeter (cc.)
1000 cubic centimeters=l cubic decimeter
1000 cubic decimeters = 1 cubic meter
3. Weight:
The unit is the gram. This is the weight of 1 cc. of pure water
at its temperature of greatest density, 4° C.
10 milligrams (mg.) =1 centigram (eg.)
10 centigrams =1 decigram (dg.)
10 decigrams =1 gram (g.)
1000 grams = 1 kilogram (kg.)
141
142 APPENDIX
The gram and the kilogram are the units of weight most
generally used by the chemist.
One ounce avoirdupois = 28.35 grams
One pound avoirdupois = 453.59 grams
One kilogram = 2.2 pounds
TEMPERATURES
Centigrade and Fahrenheit and Absolute Scales
The Centigrade Thermometer is the one used in scientific work.
The abbreviation for centigrade is C. The boiling point of
water on this thermometer is marked 100 and the freezing point
is marked 0. The 100 equal divisions between these points are
called degrees. The abbreviation for degrees is °. The boiling
point of water is written 100° C . Degrees below zero are written
as minus; thus, -20° C. means 20° below zero.
The Fahrenheit Thermometer is the one commonly used in
this country. On this thermometer the boiling point of water
is 212° F. and the freezing point of water is 32° F. above zero.
To change the Fahrenheit degrees to centigrade degrees, sub-
tract 32 and multiply the remainder by f , thus :
C.=f (F.-32)
To change centigrade degrees to Fahrenheit degrees multiply
by f and add 32 to the product, thus :
F.=f C.+32
The Absolute Temperature is the one used by scientists in
the study of gas volumes.
The point -273° C. is called the absolute zero. Absolute
temperature is reckoned from this point. Degrees on the abso-
lute scale are found by adding 273 to the readings on the centi-
grade thermometer. Thus :
10°C, = 10o+273o = 283°T.
-60°C.= -60o+273o=213°T.
APPENDIX
143
LIST OF THE COMMON ELEMENTS, THEIR SYMBOLS,
ATOMIC WEIGHTS, AND VALENCES
O = 16
i Name
Sym-
bol
Valences
At.
Wt.
Name
Sym-
bol
Valences
At.
Wt.
Aluminum
Al
3
27.1
Nickel . .
Ni
2-3
58.7
Antimony .
Sb
3-5
120.2
Nitrogen
N
3-5
14
Arsenic . .
As
3-5
75
Oxygen .
O
2
16
Barium
Ba
2
137.4
Phosphorus
P
5-3
31
Bismuth .
Bi
3
208
Potassium
K
1
39.1
Boron . .
B
3
11
Silicon
Si
4
28.3
Bromine .
Br
1-5
79.9
Silver . .
Ag
1
107.9
Cadmium .
Cd
2
112.4
Sodium
Na
1
23
Calcium
Ca
2
40.1
Sulfur . .
S
2-4-6
32.1
Carbon
C
4-2
12
Tin . .
Sn
2-4
119
Chlorine .
CI
1-5-7-3
35.5
Zinc . .
Zn
2
65.4
Chromium
Cr
3-6-7-2
52
Cobalt . .
Co
2-3
59
Copper . .
Cu
2-1
63.6
Fluorine .
F
1
19
Gold . .
Au
1-3
197.2
Hydrogen .
H
1
1
Iodine . .
I
1-5-7
127
Iron . . .
Fe
3-2
55.9
Lead . .
Pb
2-4
207.1
Magnesium
Mg
2
24.3
Manganese
Mn
2-7-4-6-3
54.9
Mercury .
Hg
2-1
200.6
THE WEIGHT IN GRAMS OF 1 LITER OF VARIOUS GASES
MEASURED UNDER STANDARD CONDITION (0 DE-
GREES C. AND 760 MM. PRESSURE)
Acetylene 1.16
Air 1.29
Ammonia 0.77
Carbon dioxide . . . . 1.98
Carbon monoxide . . . . 1.25
Chlorine 3.17
Hydrogen 0.09
Hydrogen chloride . . . 1.64
Hydrogen sulfide .... 1.54
Methane 0.72
Nitric oxide 1.34
Nitrogen 1.25
Nitrous oxide 1-98
Oxygen 143
Sulfur dioxide 2.93
144
APPENDIX
FOOD CHEMISTRY OUTLINE
Compounds Found in the Body and in Foods.
1. Definition of a food.
2. Relation of food to the body.
3. Chief elements found in the body and in foods are carbon,
oxygen, hydrogen, nitrogen, sulfur, phosphorus, calcium.
4. The elements are combined to form two classes of com-
pounds in the body and in foods :
f 1. Water, H20 (65 % or more in the body).
Inorganic < 2. Inorganic salts (mineral matter, ash, 5% in body,
[ chiefly calcium phosphate) .
1. Carbohydrates (less than 1 % in
body).
a. Starch group (C6Hio05)n.
1. Starch. 4. Cellulose.
2. Glycogen. 5. Gums.
3. Dextrin. 6. Pectin.
b. Sugars.
1. Sucrose group (C12H22O11).
a. Sucrose — cane sugar.
b. Lactose — milk sugar.
c. Maltose — malt sugar.
2. Glucose group (CeHioOe).
a. Dextrose — grape
sugar — glucose.
b. Levulose — fruit sugar
— fructose.
c. Galactose from milk
sugar.
2. Fats (12% in body — this varies).
a. Animal source.
1. Milk — cream, butter.
2. Fatty tissue — lard, tal-
low, whale oil.
b. Plant source.
1. Seeds — sunflower, cot-
ton, flax, castor bean.
2. Nuts — coconut, almond,
peanut.
3. Fruit — olive, avocado.
II. Organic
Non-nitrogenous
(contain carbon
hydrogen and
oxygen only).
APPENDIX
' 1. Albumens.
a. Egg albumen.
b. Blood albumen.
Nitrogenous
c. Milk albumen.
II. Organic
(Continued)
Substances or
Proteins
(contain car- '
bon, hydro-
2. Casein.
3. Globulins.
a. Gluten.
b. Myosin.
gen, oxygen,
and nitrogen) .
c. Legumen.
4. Albuminoids or gelatinoids.
a. Collagen.
6. Keratin.
145
a.
h.
c.
d.
B. Inorganic Compounds.
1. Water:
Most abundant inorganic compound in the body. It
forms 60 % of the body.
Tissues in which it is most abundant :
Blood, eyeballs, tears, digestive juices, muscle
tissues, lymph, all the important organs of the
body.
Tissues in which it is the least abundant :
Hair, teeth, bones, nails, skin, fatty tissues.
Use of water to the body :
It carries nourishment to and waste from living
tissues of the body. It cleans and flushes the
system. It regulates the temperature of the
body.
e. Supplied to the body :
By drinking it pure and in all beverages such as
milk, in soups, melons, fruits, and vegetables.
/. Foods with much water :
See table in Appendix.
g. Foods with little water :
See table in Appendix.
h. Foods with no water :
See table in Appendix.
146 APPENDIX
2. Inorganic salts (mineral matter or ash, 5% of body by
weight) :
a. Tissues in which it is most abundant :
Bones — Ca3(P04)2, Mg3(P04)2, CaC03, chiefly.
Hair, nails, skin — Si02, CaF2, chiefly.
Muscle tissue — Na2Cl, Na2C03, Na3P04, and
KC1, chiefly.
Blood and all liquids in the body contain nearly the
same salt as muscle tissue.
b. Tissues with little if any inorganic matter :
Fatty tissues.
c. Use of inorganic salts to the body :
To build tissues, aid digestion, and to stimulate the
appetite.
d. Foods containing much :
See table in Appendix.
e. Foods with little or none :
See table in Appendix.
C. Organic Compounds in the Body and in Foods.
1. Organic compounds in the body and in foods are divided
into two groups :
a. Non-nitrogenous, containing carbon, hydrogen, and
oxygen only.
b. Nitrogenous, containing carbon, hydrogen, oxygen,
nitrogen, sulfur, and phosphorus.
2. Non-nitrogenous compounds divided into two groups :
a. Carbohydrates :
Definition of a carbohydrate — examples*
Forms less than 1 % of the body. Why then so im-
portant a part of our diet ?
b. Fats:
Definition of a fat — example.
Why so useful in our diet ?
APPENDIX 147
D. A Study of Some of the Important Carbohydrates of the Starch Group.
1. Starch (C6Hi0O5)n :
a. Vegetables and plants in which it is most abundant.
b. How obtained commercially.
c. Physical properties :
Starch grains from different sources differ in size
and shape (microscope).
d. Chemical properties :
Effect of gentle dry heat.
Effect of intense heat without air.
Effect of concentrated sulfuric acid.
Products of combustion.
Hydrolysis of starch.
e. Manufacture of glucose from starch.
/. The iodine test for starch.
g. Foods containing much starch :
See table in Appendix.
h. Foods containing little starch :
See table in Appendix.
i. Foods containing no starch :
See table in Appendix.
j. Commercial uses of starch.
2. Dextrin (C6Hi0O5)n :
a. Prepared by heating starch from 210° C. to 280° C.
b. Physical properties, yellow or white, sweet, sticky,
soluble in water.
c. Insoluble in alcohol.
d. Intermediate product in the hydrolysis of starch.
e. Effect on iodine solution (red, purple coloration).
/. Effect on Fehling's solution.
g. Use of dextrin.
3. Glycogen :
a. Found in the liver of animals.
b. Soluble in cold water.
148 APPENDIX
c. Effect on iodine solution (reddish coloration).
d. Use of glycogen to animal.
4. Cellulose (CeHioOsJn :
a. Where found :
In nearly all plants, especially the stems, roots, and
leaves.
Commercial source is young tree trunks, cotton,
hemp, flax, jute, ramie, coconut fiber.
b. How obtained commercially.
c. Physical properties :
Seed fibers or last fibers. Colorless, odorless, taste-
less, insoluble in water.
d. Chemical properties :
Dilute acids no effect.
Dilute bases no effect.
Iodine solution no effect.
Fehling's solution no effect.
Concentrated sulfuric acid forms a clear jelly-like
mass called amyloid. Longer action forms dex-
trin. Still longer dextrose.
Strong sodium hydroxide makes cellulose fibers
transparent and larger. (Mercerizes them.)
Soluble in a concentrated solution of zinc chloride.
Soluble in Sweitzer's reagent.
Nitric and sulfuric acid changes it to nitrocellulose
or guncotton.
Nitrocellulose dissolved in ether and alcohol gives
collodion.
Nitrocellulose dissolved in ether and camphor gives
celluloid.
e. Commercial uses of cellulose.
/. Uses as food.
g. Foods containing much cellulose.
h. Foods containing little or no cellulose.
APPENDIX 149
5. Gums :
a. Where found.
b. How obtained commercially.
c. Physical properties :
Effect of cold water, alcohol, ether.
d. Chemical properties :
Effect of iodine.
Effect of Fehling's solution.
Hydrolysis of gums.
e. Use of gums in the preparation of foods.
/. Commercial uses of gums.
6. Pectin:
a. Where found.
b. Soluble in hot water.
c. Physical properties.
d. Precipitated by alcohol, acid, or sugar.
e. Hydrolyzed by long boiling with acid.
/. Fruits containing much pectin.
E. Important Carbohydrates of the Sugar Group.
1. Sucrose — cane sugar, C12H22O11 :
a. Substances containing much — roots like beets and
carrots, stems of grasses, corn stalks, sugar cane,
sap of some trees, birch and maple.
b. Commercial source — sugar cane, sugar beets.
c. Preparation of sugar from cane.
1. Extraction of juice.
2. Separation of crystals — centrifugal.
3. Clarifying.
4. Evaporation.
d. Preparation from beets.
1. Wash and slice beets.
2. Extraction of juice by diffusion cells (osmosis).
3. Clarifying.
150 APPENDIX
4. Evaporation.
5. Separation of crystals.
e. Physical properties of sucrose.
Color, odor, taste, form, solubility in hot and cold
water.
/. Chemical properties of sucrose.
Gentle heat melts it. This, when cold, forms
barley sugar:
More intense heat changes it to caramel.
Strong heat decomposes it.
CaHjBOu+heat — >- 12 C + ll H20
Concentrated sulfuric acid decomposes it.
CMHaAi + CHaSOJ — >- 12 C + ll H20
Will not reduce Fehling's solution.
Boiled with a dilute acid it hydrolyzes.
Ci2H220n+H20 (dilute acid) — >-C6H1206+C6H1206
sucrose dextrose levulose
Not easily fermented until yeast hydrolyzes it and
the simple sugars so formed undergo fermentation.
Ci2H220ii+H20 — >- C6Hi206+C6Hi206
C6H1206+yeast — >- 2 C2H5OH+2 C02
glucose alcohol carbon
dioxide
g. Use of sucrose as food.
h. Commercial uses.
2. Lactose — milk sugar, Ci2H220n.
a. Found in milk of all mammals.
b. Prepared from whey.
c. Physical properties of lactose. Color, odor, not so
sweet as cane sugar, not so soluble in cold water as
cane sugar or grape sugar, more soluble in hot
water.
d. Chemical properties of lactose.
Heat melts it.
Intense heat decomposes it.
APPENDIX 151
Sulfuric acid decomposes it.
It will reduce Fehling's solution with ^ the power
of dextrose.
Dilute acids hydrolyze it.
Ci2H220ii+H2b (dilute acid) — ^C6H1206 + C6H1206
lactose dextrose galactose
It is easily fermented by yeast.
e. Use of lactose. In the preparation of children's foods.
In pharmacy in the preparation of pellets and
tablets.
Maltose — malt sugar, Ci2H220n.
a. Preparation.
1. Malt diastase on starch.
2. Dilute acids on starch.
3. C6H10O5+H2O(diluteacid)— ^CeHioOs+C^H^On
starch dextrin maltose
b. Chemical properties.
Heat melts it.
Intense heat decomposes it.
Reduces Fehling's solution with -J the power of dex-
trose.
Easily fermented.
Dilute acids hydrolyze it.
Ci2H22On +H20 (dilute acid) — >- C6H1206+C6H1206
maltose dextrose dextrose
Dextrose-glucose — grape sugar, CeH^Oe.
a. Dextrose, a white, crystalline solid.
Glucose, a white thick sirup.
Grape sugar, heavy brown-white lumps. Three
names for the same sugar. The difference in
physical properties is due to methods of purify-
ing it.
b. Substances containing much — grapes, apples, apri-
cots, peaches, all fruits, especially dried fruits.
152 APPENDIX
c. Preparation.
(1) Hydrolysis of sucrose.
CiaHaOn+HaOCdUuteacid)— ^^BHiaOe+CeHiaOe
sucrose dextrose levulose
(2) Hydrolysis of lactose.
Ci2H22Ou+H20 (dilute acid)— ^CGH1206+C6H1206
lactose dextrose galactose
(3) Hydrolysis of maltose.
C12H220i1+H20 (dilute acid) — >■ 2 C6H1206
maltose dextrose
(4) Hydrolysis of cellulose.
2 C6H10O5+H2O (acid) — ^ C6H10O5+C6H12O6
cellulose dextrin dextrose
(5) Hydrolysis of starch — this is the commercial
method.
C6H1o05+H20(diluteacid)-^C6H1005 + Ci2H22011
starch dextrose maltose
Ci2H22On+H20 — ^ 2 C6H1206
maltose dextrose
or glucose
If conversion is not complete, the product is
glucose (mixture of dextrin, maltose, and dex-
trose).
If more complete, the product is grape sugar (dex-
trose and maltose).
If conversion is complete, the product is dextrose.
d. Physical properties of dextrose.
White, crystalline, odorless, f as sweet as sugar,
soluble in cold water, more soluble in hot
water.
e. Chemical properties of dextrose.
Moderate heat melts it.
Intense heat decomposes it.
C6H1206 — ^6C+6H20
Concentrated sulfuric acid decomposes it.
C6H1206 — ^6C+6H20
APPENDIX 153
Ferments with yeast dextrose.
CeHiaOe+yeast >- 2 C2H5OH+2 C02
alcohol carbon dioxide
Reduces Fehling's solution.
/. Uses of glucose.
5. Levulose — fruit sugar, C6Hi206
a. Found in fruits with dextrose.
b. Prepared by inversion of cane sugar.
C12H22O11+H2O (dilute acid) — ^ C6H1206+C6H1206
sucrose dextrose levulose
c. Properties similar to those of dextrose.
6. Galactose from milk sugar.
a. Prepared by hydrolysis of milk sugar.
Ci2H220n+H20 — >- C6Hi206+CeHi206
lactose gelactose dextrose
b. Properties similar to those of dextrose.
F. Fats and Oils.
1. Chemical composition of fats.
a. Fats are esters, i.e. organic salts.
b. Base -f- acid — >- salt + water.
c. Alcohol +acid — >- ester + water.
C2H5OH+CH3COOH — ^ CH3COOC2H5+H20
Ethyl alcohol acetic acid ethylacetate
d. Glycerin -(-acid — >- fat + water.
C3H5(OH)3+3 C17H35COOH — >-
glycerin stearic acid
(C17H35COO)3C3H5+3H20
stearin (a fat)
C3H6(OH)8+3 C15H31COOH — *-
glycerin palmitic acid
(C15H31COO)3C3H5+3H20
palmitin (a fat)
C3H5(OH)3+3 C17H33COOH — >-
glycerin oleic acid
(C17H33COO)3C3H5+3 H20
olein (an oil)
154 APPENDIX
e. Ordinary fats, such as lard and tallow, are mixtures of
the esters palmitin and stearin chiefly, while oils,
such as olive oil, cottonseed oil, sperm oil, con-
tain more olein than palmitin and stearin.
2. Occurrence of fats and oils.
a. Animal origin.
Milk (butter fat).
Fatty tissue (lard, tallow, whale oil, sperm oil, and
cod liver oil).
Eggs (yolks).
b. Plant origin.
Seeds (sunflower, cotton, flax, castor bean, and cacao
beans).
Nuts (coconut, almond, peanut, pecans).
Fruits (olive, avocado).
3. Methods of obtaining fats and oils.
a. Heat alone, called rendering (lard, tallow, and other
animal fats and oils).
b. Pressing without heat (olives, peanuts, cotton seeds,
and castor beans), called expressing.
c. Pressing with heat (cocoa beans, coconuts, al-
monds).
d. Extraction by means of ether, chloroform, carbon
tetrachloride.
4. Physical properties of fats.
a. Fats are solids, oils are liquids.
b. Characteristic odor and taste.
c. Insoluble in water, soluble in gasoline, ether, and
chloroform.
d. With egg albumen, gum arabic, or other mucilage-
like substances, oils and fats form emulsions.
e. Rubbed on paper, oils form a translucent spot.
This is the "grease spot" test for oils and
fats.
APPENDIX 155
5. Chemical properties of fats.
a. Intense heat decomposes fats, forming acrolein.
b. Oils burn, forming carbon dioxide and water.
c. When boiled with strong bases, fats are first hydrolyzed
and then saponified, i.e. soaps are formed. When
esters are hydrolyzed by means of sodium hy-
droxide, the organic acid and the alcohol are
formed. The acid then combines with the sodium
hydroxide to form a salt thus :
1. CH3COOC2H5+H20 — ^ CH3COOH+C2H5OH
ethyl acetate acetic acid ethyl alcohol
(by NaOH)
2. CH3COOH+NaOH — >■ CH3COONa+H20
acetic acid sodium sodium acetate
hydroxide
When fats are hydrolyzed by means of sodium
hydroxide, the organic acid and the alcohol
glycerin are formed. The acid then combines
with the sodium hydroxide to form a soap, thus :
1. (C17H35COO)3C3H5+3 H20 (by NaOH)
stearin (a fat)
— >■ 3 C17H35COOH+C3H5(OH)3
stearic acid glycerin
2. C17H35COOH+NaOH — ^ C17H35COONa+H20
stearic acid sodium sodium stearate
hydroxide (a soap)
6. Uses of fats as food.
a. Give 2-J- times as much heat to the body as the carbo-
hydrates.
7. Commercial use of fats.
a. For preserving meats and fish, for lubricants, for
varnishes, paints, soaps, candles.
Nitrogenous Substances or Proteins.
1. Albumens — soluble in cold water, coagulated by heat.
a. Where found (milk, egg, blood).
b- Physical properties — solubility.
156 APPENDIX
c. Effect of heat, odor.
d. Decomposed by soda lime gives ammonia.
e. Xanthoproteic test.
/. Millon's test.
g. Use to body.
2. Casein — soluble in cold and hot water.
a. Where found (milk of all mammals).
b. Precipitated by any acid.
c. Coagulated by rennin.
d. Effect of heat — odor.
e. Xanthoproteic test.
/. Millon's test.
g. Decomposition test.
3. Globulins — insoluble in hot or cold water.
Gluten in wheat and other cereals.
a. Physical properties — solubility.
b. Effect of heat — odor.
For other tests see 1 and 2 above.
Myosin in meat.
a. Effect of heat — odor.
For other tests see 1 and 2 above.
Legumen in peas and beans.
For tests see 1 and 2 above.
4. Albuminoids or gelatinoids — soluble in hot water, on
long boiling. Form jellies on cooling.
Collagen in cartilage, skins and bones.
a. Will not give Xanthoproteic test.
b. Will not give Millon's test.
c. When heated — odor.
d. Decomposition test.
e. Used to make commercial gelatin.
Keratin in hair, hoofs, nails, very insoluble, contains
much sulfur,
a. For chemical properties see collagen above.
APPENDIX 157
b. Contains more sulfur than other proteins.
c. Used to make glue.
d. No food value.
DIGESTION OF FOODS
Starch Group.
1. Starch.
In mouth, cooked starch changed to maltose and
dextrose.
In stomach, no change.
In small intestine, cooked and uncooked starch completely
changed to maltose and dextrose.
2. Cellulose not digested. It is softened in small intestine.
Sugar Group.
1. Sucrose, lactose, maltose.
In mouth, no change.
In stomach, the acids present partly hydrolyze them to
the simple sugars.
In small intestine, completely hydrolyzed by the ferment
invertin.
2. Glucose, levulose, galactose.
Ready for the blood without being changed.
Fats.
In the mouth, no action.
In the stomach no action.
In the small intestine :
1. Some of the fats form emulsions with the proteins
present.
2. Steapsin splits fats into fatty acids and glycerin.
C3H5(C17H35COO)3+3H20
stearin
— >■ C3H5(OH)3+3 C17H35COOH
glycerin stearic acid
158
APPENDIX
3. Then the fatty acid plus the alkali present forms soaps.
C17H35COOH+NaOH — ^ C17H35COONa+H20
fatty acid soap
4. Fat and soaps form an emulsion.
Digestion of Proteins.
1. In mouth, no action.
2. In stomach :
Dissolved proteins coagulated by rennin and acid.
All coagulated proteins changed to peptones by ferment
pepsin aided by acids.
3. In small intestine :
All proteins changed to peptones by ferment trypsin.
ACTION OF DIGESTIVE JUICES
Name of Di-
gestive
Juice
From
Action in
Alkaline
or Acid
Name of
Ferment
Action of Ferment
Saliva
Salivary
gland
Mouth
Alkaline
Ptyalin
Cooked starch to
maltose. Acts
slowly on glycogen.
No effect on cellu-
lose or uncooked
starch.
Gastric
Walls of
Stomach
Acid
1. Acid
1. Sucrose group of
juice
stom-
(lactic
alone
sugars hydro-
ach
and
lyzed to dextrose.
hydro-
2. Acid
2. Coagulates
chloric
alone
proteins.
acids)
3. Ren-
nin
4. Pep-
sin
3. Coagulates
proteins.
4. Proteins to pep-
tones. Starch
not changed in
stomach.
APPENDIX
159
Name of Di-
gestive
Juice
From
Action in
Alkaline
or Acid
Name of
Ferment
Action of Ferment
Pancreatic
Pancreas
Small
Alkaline
1. Amy-
1.
All starch to
juice
intes-
tine
lop-
sin
2. In-
ver-
ts
3. Steap-
sin
4. Tryp-
sin
2,
3.
4.
maltose.
Sucrose, maltose,
lactose to simple
sugars.
Splits fats into
fatty acids and
glycerin.
Fatty acids
plus alkalies
form soap.
Soap plus fat
forms an emul-
sion. Proteids
plus fat form
an emulsion.
Proteins to
peptones.
TABLES SHOWING AVERAGE HEIGHT, WEIGHT, SKIN
SURFACE, AND FOOD UNITS REQUIRED DAILY WITH
VERY LIGHT EXERCISE
Boys
Age
Weight in Pounds
Calories or Food Units
5
41.09
816.2
6
45.17
855.9
7
49.07
912.4
8
53.92
981.1
9
59.23
1043.7
10
65.30
1117.5
11
70.18
1178.2
12
76.92
1254.8
13
84.85
1352.6
14
94.91
1471.3
160
APPENDIX
TABLES SHOWING AVERAGE HEIGHT, WEIGHT, SKIN
SURFACE, AND FOOD UNITS REQUIRED DAILY WITH
VERY LIGHT EXERCISE {Continued)
Girls
Age
Weight in Pounds
Calories or Food Units
5
39.66
784.5
6
43.28
831.9
7
47.46
881.7
8
52.04
957.1
9
57.07
1018.5
10
62.35
1081.0
11
68.84
1148.5
12
78.31
1276.8
Men
Calories ob
Food Units
Height
Weight in
Pounds
in Inches
Proteids
Fats
Carbohydrates
Total
61
131
197
591
1182
1970
62
133
200
600
1200
2000
63
136
204
612
1224
2040
64
140
210
630
1260
2100
65
143
215
645
1290
2150
66
147
221
663
1326
2210
67
152
228
684
1368
2280
68
157
236
708
1416
2360
69
162
243
729
1458
2430
70
167
251
753
1506
2510
71
173
260
780
1560
2600
72
179
269
807
1614
2690
73
185
278
834
1768
2780
74
192
288
864
1728
2880
75
200
300
900
1800
3000
APPENDIX
Women
161
Calories or Food Units
Height
Weight in
Pounds
in Inches
Proteids
Fats
Carbohydrates
Total
59
119
179
537
1074
1790
60
122
183
549
1098
1830
61
124
186
558
1116
1860
62
127
191
573
1146
1910
63
131
197
591
1182
1970
64
134
201
603
1206
2010
65
139
209
627
1254
2090
66
143
215
645
1290
2150
67
147
221
663
1326
2210
68
151
227
681
1362
2270
69
155
232
696
1392
2320
70
159
239
717
1434
2390
Note. — With active exercise an increase of about 20 per cent total
food units may be needed.
TABLE OF 100 FOOD UNITS
Name of Food
"Portion" Con-
taining 100 Food
Units (Approx.)
Wt. of 100
Calories
Per Cent of
Beef, round, boiled (fat)
Beef, round, boiled
(lean)
Beef, round, boiled
(med.)
Beef, 5th rib, roasted
Beef, 5th rib, roasted
Beef, 5th rib, roasted
Beef, ribs, boiled . .
Cooked Meats
Small serving
Large serving
Small serving
Half serving . .
Small serving
Very small serving
Small serving
36
1.3
40
60
62
2.2
90
10
44
1.6
60
40
18.5
.65
12
88
32
1.2
25
75
25
.88
18
82
30
1.1
27
73
00
00
00
00
00
00
00
162
APPENDIX
TABLE OF 100 FOOD UNITS (
Continued)
Wt. of 100
Calories
Per Cent
OF
"Portion" Con-
taining 100 Food
Name of Food
Units (Approx.)
go
s
c3
1
c
3
-a
o
ta
c3 s.
6
o
£
fa
O-d
Cooked Meats (Continued)
Beef, ribs, boiled . .
Very small serving
25
.87
21
79
00
Chicken, canned . .
One thin slice
27
.96
23
77
00
Lamb chops, boiled, av.
One small chop .
27
.96
24
76
00
Lamb, leg, roasted
Ord. serving . .
50
1.8
40
60
00
Mutton, leg, boiled .
Large serving
34
1.2
35
65
00
Pork, ham, boiled (fat)
Small serving
20.5
.73
14
86
00
Pork, ham, boiled . .
Ord. serving . .
32.5
1.1
28
72
00
Pork, ham, roasted (fat)
Small serving
27
.96
19
81
00
Pork, ham, roasted
(lean)
Small serving
34
1.2
33
67
00
Turkey, as pur., canned
Small serving
28
.99
23
77
00
Veal, leg, boiled . .
Large serving
67.5
2.4
73
27
00
Uncooked Meats, Edibi
,e Portion
Beef, loin, av. (lean)
Ord. serving . .
50
1.8
40
60
00
Beef, loin, av. (fat)
Small serving
30
1.1
22
78
00
Beef, loin, porterhouse
steak, av
Small steak . .
36
1.3
32
68
00
Beef, loin, sirloin steak,
av
Small steak . .
40
1.4
31
69
00
Beef, ribs, lean, av. .
Ord. serving . .
52
1.8
42
58
00
Beef, round, lean, av.
Ord. serving . .
63
2.2
54
46
00
Beef, tongue, av. . .
Ord. serving . .
62
2.2
47
53
00
Chicken (broilers), av.
Large serving
90
3.2
79
21
00
Clams, round in shell,
av
Twelve to 16 . .
210
7.4
56
8
36
Cod, whole ....
Two servings . .
138
4.9
95
5
00
Goose (young), av.
Half serving . .
25
.88
16
84
00
Halibut steaks, av.
Ord. serving . .
81
2.8
61
39
00
Liver (veal), av. . .
Two small serv-
ings ....
79
2.8
61
39
00
Lobster, whole, av.
Two servings
117
4.1
78
20
2
Mackerel (Span.),
whole, av
Ord. serving . .
57
2
50
50
00
APPENDIX
163
Name of Food
"Portion " Con-
taining 100 Food
Units (Approx.)
Wt. of 100
Calories
Per Cent cf
Uncooked Meats, Edible Portion {Continued)
Mutton leg, hind, lean,
av
Oysters, in shell, av. .
Pork, loin chops, av. .
Pork, ham, lean, av. .
Pork, bacon, med. fat,
av
Salmon (Cal.), av. . .
Shad, whole, av. . .
Trout, brook, whole,
av
Turkey, av.
Artichokes, av., canned
Asparagus, av., canned
Asparagus, av., cooked
Beans, baked, canned
Beans, Lima, canned .
Beans, string, cooked .
Beets, edible portion,
cooked
Cabbage, edible por-
tion
Carrots, edible portion,
fresh
Carrots, cooked . .
Cauliflower, as pur-
chased
Celery, edible portion
Corn, sweet, cooked .
Cucumbers, edible por-
tion
Ord. serving . .
One dozen . . .
Very small serving
Small serving
Small serving
Small serving
Ord. serving . .
Two small serv-
ings ....
Two small serv-
ings
Vegetables
Small side dish
Large side dish
Five servings .
Three servings
Two servings
One side dish
50
1.8
41
59
193
6.8
49
22
27
.97
18
82
36
1.3
29
71
15
.53
6
94
42
1.5
30
70
60
2.1
46
54
100
3.6
80
20
33
1.2
29
71
430
15
14
0
540
19
33
5
206
7.19
18
63
75
2.66
21
18
126
4.44
21
4
480
16.66
15
48
245
8.7
2
23
310
11
20
8
215
7.6
10
8
164
5.81
10
34
312
11
23
15
540
19
24
5
99
3.5
13
10
565
20
18
10
164
APPENDIX
TABLE OF 100 FOOD UNITS {Continued)
Name of Food
"Portion" Con-
taining 100 Food
Units (Approx.)
Wt. op 100
Calories
Per Cent of
Vegetables {Continued)
Egg plant, edible por-
tion
Lettuce, edible portion
Mushrooms, as pur-
chased
Onions, fresh, edible
portion
Onions, cooked . . .
Parsnips, edible portion
Parsnips, cooked .
Peas, green, canned
Peas, green, cooked
Potatoes, baked
Potatoes, boiled
Potatoes, mashed
(creamed) . . .
Potatoes, steamed .
Potatoes, chips . .
Potatoes, sweet, cooked
Pumpkins, edible por-
tion
Radishes, as purchased
Rhubarb, edible por-
tion
Spinach, cooked . .
Squash, edible portion
Succotash, canned . .
Tomatoes, fresh as
purchased ....
Tomatoes, canned . .
Turnips, edible portion
Vegetable oysters . .
Two large serv
ings . . .
1| servings
Two servings .
One serving .
One good sized
One large sized
One serving .
One serving .
One half serving
Half av. potato
Two ord. servings
Ord. serving . .
Four av. . . .
Two large servings
350
12
17
10
505
18
25
14
215
7.6
31
8
200
7.1
13
5
240
8.4
12
40
152
5.3
10
7
163
5.84
10
34
178
6.3
25
3
85
3
23
27
86
3.05
11
1
102
3.62
11
1
89
3.14
10
25
101
3.57
11
1
17
.6
4
63
49
1.7
6
9
380
13
15
4
480
17
18
3
430
15
10
27
174
6.1
15
66
210
7.4
12
10
100
3.5
15
9
430
15
15
16
431
15.2
21
7
246
8.7
13
4
273
9.62
10
51
APPENDIX
165
Name of Food
"Portion " Con-
taining 100 Food
Units (Approx.)
Wt. of 100
Calories
Per Cent of
Apples, as purchased .
Apricots as purchased
Dates, edible portion .
Dates, as purchased .
Figs, edible portion
Prunes, edible portion
Prunes, as purchased .
Raisins, edible portion
Raisins, as purchased .
Fruits (Dried)
Three large
One large .
Three large
34
1.2
3
7
35
1.24
7
3
28
.99
2
7
31
1.1
2
7
31
1.1
5
0
32
1.14
3
0
38
1.35
3
0
28
1
3
9
31
1.1
3
9
Fruits (Fresh or Cooked)
Apples, as purchased .
Apples, baked . . .
Apples, sauce . . .
Apricots, edible portion
Apricots, cooked . .
Bananas, edible portion
Blackberries ....
Cantaloupe ....
Cherries, edible portion
Cranberries, as pur-
chased
Grapes, as purchased,
av. . .
Grape fruit
Grape juice
Lemons
Lemon juice
Nectarines
Olives, ripe
Oranges, as purchased
av
Oranges, juice . .
Peaches, as purchased,
Two apples . ,
Ord. serving . ,
Large serving
One large . . ,
Half ord. serving
Small glass
About seven .
One very large
Large glass
Three ordinary
206
7.3
3
7
94
3.3
2
5
111
3.9
2
5
168
5.92
8
0
131
4.61
6
0
100
3.5
5
5
170
5.9
9
16
243
8.6
6
0
124
4.4
5
10
210
7.5
3
12
136
4.8
5
15
215
7.57
7
4
120
4.2
0
0
215
7.57
9
4
246
8.77
0
0
147
5.18
4
0
37
1.31
2
91
270
9.4
6
3
188
6.62
0
0
290
10
7
2
166
APPENDIX
TABLE OF 100 FOOD UNITS {Continued)
Name of Food
"Portion" Con-
taining 100 Food
Units (Approx.)
Wt. of 100
Calories
Per Cent of
Fruits
(Fresh or Cooked) {Continued)
Peaches, sauce . . .
Ord. serving . .
136
4.78
4
2
94
Peaches, juice . . .
Ord. glass . . .
136
4.80
0
0
100
Pears ......
One large pear .
173
5.40
4
7
89
Pears, sauce ....
113
3.98
3
4
93
Pineapples, edible por-
tion, av
226
8
4
6
90
Raspberries, black . .
146
5.18
10
14
76
Raspberries, red . .
178
6.29
8
0
92
Strawberries, av. . .
Two servings . .
260
9.1
10
15
75
Watermelon, av. . .
760
27
6
6
88
Dairy Products
Butter
Ordinary pat . .
12.5
.44
.5
99.5
00
Buttermilk ....
1§ glasses .
275
9.7
34
12
54
Cheese, Am., pale . .
1\ cu. in. .
22
.77
25
73
2
Cheese, cottage . . .
Four cu. in
89
•3.12
76
8
16
Cheese, full cream . .
1^ cu. in. .
23
.82
25
73
2
Cheese, Neufchatel
\\ cu. in. .
29.5
1.05
22
76
2
Cheese, Swiss . . .
1| cu. in. . .
23
.8
25
74
1
Cheese, pineapple . .
If cu. in. .
20
.72
25
73
2
Cream
\ ord. glass
49
1.7
5
86
9
Milk, condensed,
sweetened ....
30
1.06
10
23
67
Milk, condensed,
unsweetened . . .
59
2.05
24
50
26
Milk, skimmed . . .
1| glasses . . .
255
9.4
37
7
56
Milk, whole ....
Small glass
140
4.9
19
52
29
Cakes, Pastry, Puddings, and Desserts
Cake, chocolate layer .
Half ord. sq. pc.
28
.98
7
22
71
Cake, gingerbread . .
Half ord. sq. pc.
27
.96
6
23
71
Cake, sponge . . .
Small piece . .
25
.89
7
25
68
Custard, caramel .
71
2.51
19
10
71
APPENDIX
167
Name of Food
"Portion" Con-
taining 100 Food
Units (Approx.)
Wt. of 100
Calories
Per Cent of
Cakes, Pastry, Puddings, and Desserts {Continued)
Custard, milk .
Custard, tapioca
Doughnuts .
Lady fingers .
Macaroons .
Pie, apple
Pie, cream
Pie, custard .
Pie, lemon
Pie, mince
Pie, squash .
Pudding, apple sago
Pudding, brown betty
Pudding, cream rice .
Pudding, Indian meal
Pudding, apple tapioca
Tapioca, cooked . .
Catsup, tomato, av. .
Candy, plain . . .
Candy, chocolate . .
Honey
Marmalade, orange
Molasses, cane . . .
Olives, green, edible
portion
Olives, ripe, edible por-
tion
Pickles, mixed . . .
Sugar, granulated . .
Sugar, maple
Sirup, maple
Ordinary cup
f ordinary .
§ doughnut
Two
Four
\ piece
\ piece
| piece
| piece
\ piece
-j piece
\ ord. serving
Very small serving
\ ord. serving
Small serving
Ordinary serving
Sweets and Pickles
Four teaspoons
Five to seven
Five to seven
Three heaping tea-
spoons or I2
lumps . . .
Four teaspoons .
Four teaspoons .
122
4.29
26
56
69.5
2.45
9
12
23
.8
6
45
27
.95
10
12
23
.82
6
33
38
1.3
5
32
30
1.1
5
32
55
1.9
9
32
38
1.35
6
36
35
1.2
8
38
55
1.9
10
42
81
3.02
6
3
56.6
2
7
12
75
2.65
8
13
56.6
2
12
25
79
2.8
1
1
108
3.85
1
1
170
6
10
3
26
.9
0
0
30
1.1
1
4
30
1.05
1
0
28.3
1
.5
2.5
35
1.2
.5
0
32
1.1
1
84
38
1.3
2
91
415
14.6
18
15
24
.86
0
0
29
1.03
0
0
35
1.2
0
0
100
100
100
168 APPENDIX
TABLE OF 100 FOOD UNITS {Continued)
Name of Food
"Portion" Con-
taining 100 Food
Units (Approx.)
Wt. of 100
Calories
Per Cent of
Almonds, av. . .
Brazil nuts . . .
Chestnuts, fresh, av.
Filberts, av. . . .
Peanuts, av. . . .
Pecans, polished
Pine nuts (pignolias)
Walnuts, California
Bread, brown, av. . .
Bread, corn (johnny-
cake), av
Bread, white, home
made
Cookies, sugar . . .
Corn flakes, toasted .
Corn meal, granular,
av
Corn meal, unbolted,
av
Crackers, graham
Crackers, oatmeal
Crackers, soda .
Hominy, cooked
Macaroni, av. .
Macaroni, cooked
Oatmeal, boiled
Popcorn . . .
Popcorn, uncooked
Rice, boiled . .
Rice, flakes . .
Nuts (Edible Portion)
Eight to fifteen
Three ordinary size
Ten nuts . .
Thirteen double
About eight .
About eight .
About six . .
Cereals
Ord. thick slice
Small square . .
Ord. thick slice .
Two ....
Ord. cereal dish
full ....
2\ level table-
spoons . . .
Three tablespoons
Two ....
Two ....
3£ "Uneedas" .
Large serving
Ord. serving . .
\\ servings . .
Ord. cereal dish
Ord. cereal dish
15
.53
13
77
e
14
.49
10
86
40
1.4
10
20
14
.48
9
84
18
.62
20
63
13
.46
6
87
16
.56
22
74
14
.48
10
83
43
1.5
9
7
38
1.3
12
16
38
1.3
13
6
24
.83
7
22
27
.97
11
1
27
.96
10
5
26
.92
9
11
23
.82
9.5
20.5
23
.81
11
24
24
.83
9.4
20
120
4.2
11
2
27
.96
15
2
110
3.85
14
15
159
5.6
18
24
.86
11
11
28
.98
9
87
3.1
10
27
.94
8
APPENDIX
169
Name of Food
"Portion" Con-
taining 100 Food
Units (Approx.)
Wt. of 100
Calories
Per Cent of
Rolls, Vienna, av. . .
Shredded wheat . .
Spaghetti, av. . . .
Wafers, vanilla . . .
Wheat, flour, entire
wheat, av. . . .
Wheat, flour, graham
Wheat, flour, patent,
family, and straight
grade spring wheat
Zweiback
Eggs, hen's, boiled .
Eggs, hen's, whites
Eggs, hen's, yolks .
Omelet ....
Soup, beef, av. . .
Soup, bean, av. . .
Soup, cream of celery
Consomme . . .
Clam chowder . .
Chocolate, bitter .
Cocoa
Ice cream (Phila.) .
Ice cream (N. Y.) .
Cereals {Continued)
One large . . .
One biscuit . .
Four ....
Four tablespoons
4^ tablespoons
Four tablespoons
Size thick slice of
bread . . .
Miscellaneous
One large egg
Of six eggs
Two yolks
Very large plate
Two plates
Two plates
Half a square
Half serving .
Half serving .
35
1.2
12
7
27
.94
13
4.5
28
.97
12
1
24
.84
8
13
27
.96
15
5
27
.96
15
5
27
.97
12
3
23
.81
9
21
59
2.1
32
68
181
6.4
100
0
27
.94
17
83
94
3.3
34
60
380
13
69
14
150
5.4
20
20
180
6.3
16
47
830
29
85
00
230
8.25
17
18
16
.56
8
72
20
.69
17
53
45
1.6
5
57
48
1.7
7
47
81
82.5
87
79
80
80
85
70
00
00
00
6
17
60
37
15
65
20
30
38
46
SPECIAL SOLUTIONS
1. Cleaning Solution :
Dissolve 25 grams of commercial sodium dichromate in
150 cc. of water, then add 100 cc. of concentrated commercial
sulfuric acid. The solution can be used repeatedly.
170 APPENDIX
2. Fehling's Solution :
No. 1. Dissolve 34.64 grams of copper sulfate in 500 cc. of
distilled water.
No. 2. Dissolve 173 grams of Rochelle salts and 50 grams
of sodium hydroxide in 500 cc. of water. Keep the two solutions
in separate bottles. Mix equal parts just before using. The
mixture must be alkaline. (For glucose test.)
3. Haine's Solution :
Dissolve 10 grams of CuSC>4 • 5 H20 in 875 cc. of water and
add 45 grams of KOH sticks. Add 100 cc. of glycerin. This
is a single solution reagent and will keep for a year. (Test for
glucose.)
4. Halphen's Reagent :
Dissolve 1 gram of sulfur in 100 cc. of carbon disulfide and
then add 100 cc. of amyl alcohol. (Test for cottonseed oil.)
5. Iodine (Tincture) :
Dissolve 7 grams of iodine and 5 grams of potassium iodide in
100 cc. of 95 % alcohol.
6. Iodine (Starch Test) :
5 grams iodine and 10 grams potassium iodide in 250 cc. of water
(starch test).
7. Ink Eradicator :
No. 1. Tartaric acid, 20 grams dissolved in 100 grams of
water.
No. 2. Boil 5 grams of chlorinated lime in 100 cc. of water
until pink color appears. Filter and add enough water to make
up to 100 cc. Apply No. 1, absorb excess with blotter, and then
apply No. 2. Sponge with ammonia, if used on clothing. Do
not use on wool or silk. The following solutions may be used :
No. 1. 8 grams of citric acid, 50 cc. of water, and 12 cc. of a satu-
rated solution of borax. No. 2. Boil 18 grams of chlorinated
APPENDIX 171
lime in 60 cc. of water ; filter and add 12 cc. of a saturated sol.
of borax. Use as in the first case. Not for wool or silk.
8. Javelle Water :
Dissolve 120 grams of sodium carbonate in 250 cc. of water.
Stir 30 grams of chlorinated lime into 250 cc. of hot water.
Mix the two solutions and decant the clear liquid for use as
Javelle water.
9. Litmus Solution Indicator :
Powdered litmus should first be heated in alcohol to the boiling
point. Filter the undissolved solid from the liquid and allow
it to remain for several hours in cold water to remove alkaline
impurities. Finally boil the solid residue with about 5 times
its weight of water to make the solution for use. Preserve the
solution by adding a little chloroform.
10. Logwood Solution :
Boil logwood chips in water till the solution is dark in color.
Filter. It must be freshly prepared.
11. Low's Reagent :
Mix 4 volumes of glacial acetic acid with 1 volume of con-
centrated sulfuric acid.
12. Loewe's Reagent :
Dissolve 35 grams of copper sulfate in 250 cc. of water, and
add 12 cc. of glycerin. Add enough sodium hydroxide to dis-
solve the precipitate that is formed when the hydroxide is first
added.
13. Millon's Reagent :
Dissolve mercury in twice its weight of concentrated nitric
acid. Dilute with an equal volume of cold water. Decant
the clear liquid.
14. Methyl Orange Indicator :
Mix 0.4 gram of methyl orange powder with 30 cc. of 95 %
ethyl alcohol and 170 cc. of water.
172 APPENDIX
15. Nessler's Solution :
To 50 grams of potassium iodide in distilled water add satur-
ated solution of mercuric chloride to red precipitation. Add
350 cc. of a 50 per cent potassium hydroxide solution. Make
up to one liter and allow to settle.
16. Nickel Hydroxide Solution :
Dissolve 5 grams of nickel sulfate in 100 cc. of water and
add a solution of NaOH until all the nickel is precipitated as
hydroxide. Wash it well and dissolve it in 25 cc. of concen-
trated NH4OH and 25 cc. of water. This solution dissolves silk
at once, and reduces the weight of vegetable fibers only \%
and of wool only \ %.
17. Phenolphthalein Indicator :
Dissolve 0.4 gram of phenolphthalein in 120 cc. of 95 % ethyl
alcohol and add 80 cc. of distilled water.
18. Potassium Hydroxide in Alcohol :
10 grams stick KOH dissolved in 100 grams of alcohol.
19. Potassium Permanganate, Alkaline :
KOH, 200 grams ; KMn04, 8 grams ; distilled water, 1250 cc.
Boil down to 1 liter.
20. Standard Soap Solution :
10 grams of white castile soap dissolved in 1 liter of dilute
alcohol (one third water). Filter if not clear.
21. Sulphanilic Acid :
1 gram of solid in 100 cc. of hot distilled water.
22. Sweitzer's Solution :
Slowly add CuS04 solution to NaOH solution to precipitation.
Filter. Dissolve the residue in NH4OH. Freshly prepared,
it should dissolve cotton immediately.
23. Wood Stain, Acid Proof :
I. Dissolve 125 grams each of CuS04 and KCIO3 in the same
liter of water.
APPENDIX 173
II. 150 grams of anilin oil mixed with 180 grams concentrated
HC1 and a liter of water.
Apply 2 coats of the boiling hot solution I with a brush.
Allow each coat to dry. Apply 2 coats of solution II in the
same manner. When the wood is dry, wash with hot soap-
suds. Finish with raw linseed oil or hot liquid paraffin, and
refinish with paraffin when the tables become dingy.
24. Cobalt Chloride Test Paper:
Dissolve 20 grams of CoCl2 • 6 H20 in about 200 cc. of
water. Wet filter paper with the solution and dry it. Cutt
into strips. Dry it over a flame before using it. Be careful
in drying not to scorch the paper.
25. Acid Mercuric Nitrate :
Dissolve metallic mercury in twice its weight of concen-
trated HN03 (sp. gr. 1.42) and dilute with twenty -five times
its volume of water.
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