y.PJ^. B C. LIBRARY

3 9424 00409 1390

STORAGE HEM
FiiOClESSING-OxNE

Lpl-JDllF

U.B.C. LIBRARY

fy)rl

Arrcr.i'uttt JCrr

1^

r

>v^>'

Digitized by tine Internet Arciiive

in 2010 witii funding from

University of Britisii Columbia Library

http://www.arGhive.org/details/GhemistryofplanOOsnyd

THE CHEMISTRY

OF

PLANT AND ANIMAL LIFE

■j^'^yi^

THE CHEMISTRY

OF

PLANT AND ANIMAL LIFE

BY

HARRY SNYDER, B.S.

PROFESSOR OF AGRICULTURAL CHEMISTRY, UNIVERSITY OF

MINNESOTA, AND CHEMIST OF THE MINNESOTA

AGRICULTURAL EXPERIMENT STATION

THE MACMILLAN COMPANY

LONDON: MACMILLAN & CO., Ltd.
1905

All rights reserved

CorVRIGHT, 1903,

By harry SNYDER.

Copyright, 1903,
By the MACMILLAN COMPANY.

First published elsewhere. New Edition set up, electrotyped,
and published December, 1903 ; December, 1905.

ICortoooli ^rcss

J. S. Gushing & Co. — Berwick & Smith Co.
Norwood, Mass., U.S.A.

PREFACE

THIS book is the outgrowth of instruction in chem-
istry given in the School of Agriculture of the
University of Minnesota. At first the classes were small
and individual work with blackboard exercises and
references to the literature in the school Hbrary was
possible. With increased number of students, mimeo-
graphed notes were supplied until finally the size of the
classes and the volume of the notes have necessitated
their pubHcation in book form. The work was first
given, in 1891, to a class of seven students, while in 1903
they numbered 1 50.

The class of students to whom this instruction has
been given have been mostly earnest workers who
attended school largely from personal choice and who
desired to make as much progress as possible. Numer-
ous questions have been asked by them relating to the
application of chemistry to farm and everyday life, and
for a number of years the author kept a question box in
which were placed the more important questions asked in
class, and the difficulties experienced in the laboratory
work, and in developing the work from year to year
these questions and difficulties have been considered.

This work was originally outlined as Agricultural
Chemistry, but as special features have been developed
and published, as the " Chemistry of Soils and Fertil-
izers," and "The Chemistry of Dairying," this part of
the subject has gradually developed into " The Chemistry
of Plant and Animal Life," and includes the composition

PREFACE

of plant and animal bodies, the chemistry of the plant
and of its food and growth, the chemistry of human
foods and animal nutrition, the digestibility and value of
foods and the laws governing their economic use. A few
topics of an industrial nature but closely related to plant
and animal life are also included.

Before taking up the special parts relating to the chem-
istry of plant and animal bodies, the elements and simpler
compounds present in plants and animals, together with
the laws governing their combinations, are considered so
as to prepare the way for a more intelligent study of the
subject, and to show the relation which exists between
chemistry and plant and animal life. Laboratory prac-
tice forms an important feature, and questions are asked
in connection with each experiment. Many of the ex-
periments and problems are given to illustrate some
special feature of the composition of plant and animal
bodies. The illustrations, with the exception of a few
as noted, are original.

With mature earnest students, six months with a class-
room or laboratory exercise each day are required to
complete this work, although a longer time could ad-
vantageously be given to the subject. It has been the
aim throughout to present the topics in such a way that
they would be easily understood and to develop the rea-
soning powers of the student so that he would be able to
make the best use of his chemistry in everyday life

^^^^^^- Harry Snyder.

St. Anthony Park, Minn.
First edition, March i, 1903.
Second edition, Nov. 11, 1903.

INTRODUCTION

LANT life and animal life are dependent upon
the changes which are continually taking
place in nature. The laws of nature, as far
as they are known, are set forth in the
various sciences among which chemistry oc-
cupies a prominent place. In every-day life
affairs, chemistry takes an important part because it
is the science which treats of the composition and uses
of substances found in nature. Plant and animal foods
which are essential for life are simply mechanical mix-
tures of various forms of matter which are constantly
undergoing changes and exemplifying the laws of chem-
istry. In agriculture, chemistry takes an important
part, the term Agricultural Chemistry being applied to
that branch of the science which concerns itself with the
practical application of the laws of chemistry to the
science of agriculture.

In the cultivation of the soil, production of crops, feed-
ing of animals manufacture of farm products, prepara-
tion and use of human foods, and in all life processes
numerous chemical changes take place, and it is in part
the province of chemistry to investigate these changes so
as to assist nature in rendering the plant food of the soil
more available, and to produce crops of the highest
nutritive value, as well as to indicate ways in which the
best possible use can be made of farm products in the

VI INTRODUCTION

feeding of animals and men. Before these subjects can
be considered in an intelligent way, a fundamental knowl-
edge must be obtained of some of the basic principles and
laws of chemistry, since they are as essential to future
work along special lines, as is a good foundation to a
building, or a scaffold during its construction. In the
household, arts, industries, and professions, constant
use is made of products formed from the soil, air and
water. In order to understand more perfectly the nature
of the substances dealt with so as to make the most intel-
ligent use of them, it is necessary to have a practical
knowledge of some of the laws of chemistry and of the
properties of the elements and compounds which enter
into the composition of plant and animal bodies.

To the student who begins the study of chemistry, it
is imperative that the first part of the subject be thor-
oughly mastered. Chemistry is different in its nature
from many subjects. It cannot be studied in discon-
nected parts but must be undertaken systematically. It
cannot be absorbed by listening to lectures, but must be
studied. If the first part of the work is neglected, a
failure is almost inevitable. If particular attention is
given to the elements and their combinations, to the com-
position of matter, to laboratory manipulations, and
to the classification of the elements, and if the experi-
ments are performed regularly, the student experiences a
keen enjoyment in the subject, the work ceases to be
drudgery and becomes a pleasure.

The student should make an effort to learn how to
study ; the memorizing of chemical formulas and equa-

INTRODUCTION VU

tious is not studying chemistry ; he should master the
principles governing the combination of elements and
then the memorizing of chemical formulas becomes un-
necessary. In the preparation of the lessons, there are a
number of reference books which should be consulted
occasionally. For example, if difficulty is experienced
with the subject of valence and radicals, the interesting
chapter upon these topics in Ellen H. Richards'
' * Chemistry of Cooking and Cleaning ' ' should be read.
Remsen's "Chemistry," Hart's "Chemistry for Begin-
ners," Storer and Lindsay's "Elementary Manual of
Chemistry, ' ' as well as many others, will be found valuable.
In studying the parts relating to foods, crops, and ani-
mal feeding, Henry's "Feeds and Feeding," Jordan's
"Feeding of Farm Animals," Armsby's "The Principles
of Animal Nutrition," " Johnson's How Crops Grow,"
and " How Crops Feed,'' and the bulletins of the U. S.
Department of Agriculture and of the several stations
should be available. The student should early acquire the
habit of consulting other works, as many topics are pre-
sented more clearly in one work than in another.

He who studies chemistry from a professional point of
view, as medical chemistry, pharmaceutical chemistry,
or agricultural chemistry, should remember that because
of the limited time for the subject in professional schools,
he is receiving at the best only a very abridged course in
the science. Hence the necessity of supplementing the
work by collateral reading and study ; otherwise he comes
into contact with only one phase of the subject, and
while he receives a technical education, he may obtain

Vlll INTRODUCTION

only a limited and narrow view of the science of chem-
istry.

In the study of the " Chemistry of Plant and Animal
Life," it is the aim to bring the student into close contact
with nature which is one of the requisites for perfect agri-
culture. Although not all of the laws relating to the chem-
istry of plant and animal life have been discovered, many
of those relating to soils and foods, particularly human
foods, are known and can be applied to every-day life
affairs.

CONTENTS

INTRODUCTION

Chemistry in its relation to plant and animal life ; Relation to
other sciences ; How to study chemistry ; Reference books and how
to use them ; Importance of chemistry. Pages v-viii.

CHAPTER I
Composition of Matter. — Physical and chemical changes ; Inde-
structibility of matter ; Molecules ; Atoms ; Elements ; Com-
pounds ; Chemical affinity ; Mechanical mixtures ; Chemical anal-
ysis and synthesis ; Summary. Pages 1-7.

CHAPTER II
Properties of Elements and Compounds. — Physical properties ;
Chemical properties ; Symbols of the elements ; Formulas of com-
pounds ; Atomic weights ; Molecular weights ; Law of definite
proportion ; Valence ; Combination of elements ; Problems on
combination of elements; Experiments and questions. Pages 8-18.

CHAPTER III
Laboratory Manipulation. — Importance of laboratory practice ;
Names and uses of apparatus ; Cutting glass tubing ; Bending glass
tubing ; Perforating corks ; Weighing ; Measuring liquids ; Obtain-
ing reagents from bottles ; Filtering ; Laboratory note-book ;
Breakage of apparatus ; Care of sinks and plumbing ; How to ac-
complish the best results in the laboratory. Pages 19-30.

CHAPTER IV
Oxygen. — Occurrence ; Preparation ; Properties ; Importance ;
Problems, experiments, and questions ; Part taken in plant and
animal life. Pages 31-36.

CHAPTER V
Hydrogen. — Occurrence ; Preparation ; Properties ; Importance ;

X CONTENTS

Problems, experiments, and questions ; Part taken in plant and
animal life. Pages 37-41.

CHAPTER VI
Nitrogen. — Occurrence ; Preparation ; Properties ; Importance ;
Problems, experiments, and questions ; Part taken in plant and
animal life. Pages 42-45.

CHAPTER VII
Carbon. — Occurrence ; Preparation ; Properties ; Coal ; Allotro-
pism ; A reducing agent ; Combustion ; Spontaneous Combustion ;
A decolorizer and deodorizer ; Products of combustion ; Com-
pounds of carbon ; Importance ; Experiments and questions ; Part
taken in plant and animal life. Pages 46-55.

CHAPTER VIII
Water. — Chemical composition ; Physical properties ; Wqter of
crystallization ; Natural waters ; Impurities and relation to dis-
eases ; Location of wells ; Mineral impurities ; Contamination of
drinking water ; Methods of improving drinking waters ; Water
filters ; Experiments and questions. Pages 56-65.

CHAPTER IX
Air. — A mechanical mixture ; Carbon dioxid ; Ammonium com-
pounds ; Moisture ; Ozone and hydrogen peroxid ; Argon and
helium ; Organic impurities and ventilation of rooms ; Air, a source
of plant food ; Sources of contamination of air; Experiments and
questions; Importance of air in plant and animal life. Pages 66-71.

CHAPTER X
Acids, Bases, Salts and Neutralization. — Classification of ele-
ments; Acids; Bases; Salts; Radicals; Naming of acids; Naming
of bases ; Naming of Salts ; Double salts ; Acid salts ; Basicity of
acids ; Two series of salts. Pages 72-79.

CHAPTER XI
Hydrochloric Acid, Chlorin and Chlorids. — Occurrence ; Prepara-
tion ; Properties ; Preparation of chlorin ; Properties ; The chlorin

CONTENTS XI

group of elements ; Chlorids ; Problems ; Experiments and ques-
tions. Pages 80-85.

CHAPTER XII
Nitric Acid and Nitrogen Compounds. — Occurrence ; Preparation ;
Properties ; Importance ; Ammonia ; Occurrence ; Preparation ;
Properties ; Uses ; Oxids of nitrogen ; Anhydrids ; Law of nmltiple
proportion ; Importance of the nitrogen compounds ; Problems ;
Experiments and questions. Pages 86-92.

CHAPTER XIII
Phosphorus and Its Compounds. — Occurrence ; Preparation ;
Properties ; Oxids ; Phosphoric acid c»nd phosphates ; Compounds
of phosphorus; Importance of phosphorus and its compounds;
Problems ; Experiments and questions. Pages 93-96.

CHAPTER XIV
Sulfur and Its Compounds. — Occurrence ; Preparation ; Proper-
ties ; Uses; Sulfur dioxid ; Sulfuric acid; Properties of H2SO4 ;
Sulfates ; Sulfids ; Problems ; Experiments and questions. Pages
97-102.

CHAPTER XV
Silicon and Its Compounds. — Occurrence ; Preparation and proper-
ties ; Silicic acid ; Dialysis ; Silicates ; Importance of compounds of
silicon ; Problems ; Experiments and questions. Pages 103-106.

CHAPTER XVI
Oxids of Carbon, Carbonates, and Carbon Compounds. — Carbon

dioxid ; Carbon monoxid ; Marsh gas ; Hydrocarbons ; Petroleum ;
Use of gasoline ; Illuminating gas ; Mineral oils ; Oil of turpentine ;
Creosote ; Benzene or benzol ; Aliphatic and aromatic series of com-
pounds ; Carbon disulfid ; Cyanids ; Carbids ; Fuels ; Caloric value
of fuels ; Foods ; Production of organic compounds in plants , De-
cay of organic compounds ; Experiments. Pages 107-119.

CHAPTER XVII
Writing Equations. — Importance ; Common errors in writing

Xll CONTENTS

equations ; Impossible reactions ; A knowledge of reacting com-
pounds and products necessary ; Equations for class room work.
Pages 120-126.

CHAPTER XVIII
Potassium, Sodium, and Their Compounds. — Occurrence of potas-
sium ; Potassium hydroxid ; Potassium nitrate ; Potassium car-
bonate ; Potassium chlorate : Potassium sulfate ; Miscellaneous
potassium salts ; Occurrence of sodium ; Sodium chlorid ; Sodium
nitrate ; Sodium carbonate ; Sodium hydroxid ; Sodium phosphate;
Miscellaneous sodium salts ; Experiments. Pages 127-133.

CHAPTER XIX
Calcium, Magnesium, and Their Compounds. — Occurrence of cal-
cium ; Calcium carbonate ; Calcium oxid ; Calcium hydroxid ; Cal-
cium sulfate ; Calcium chlorid ; Bleaching-powder ; Calcium phos-
phate ; Mortar ; Glass ; Occurrence of magnesia ; Magnesium salts ;
Experiments. Pages 134-139.

CHAPTER XX
Iron, Aluminum, and Their Compounds.— Occurrence of iron ;
Reduction of iron ores ; Wrought iron ; Steel ; Rusting of iron ;
Iron compounds ; Occurrence of aluminum ; Alums ; Pottery ; Ex-
periments. Pages 140-147.

CHAPTER XXI
Copper, Zinc, Lead, Tin, Arsenic, Mercury, Their Compounds and
Alloys. — Commercial importance ; Occurrence of copper and its
metallurgy ; Copper sulfate ; Bordeaux mixture ; Occurrence of
zinc ; Compounds of zinc ; Galvanized iron ; Occurrence of tin ; Tin
salts ; Occurrence of lead ; Oxids of lead ; Lead carbonates ; Lead
salts ; Uses of lead ; Occurrence of arsenic ; Paris green ; Occur-
rence of mercury ; Compounds of mercury ; Experiments. Pages

148-154.

CHAPTER XXII
The Water-Content and Ash of Plants. — Water; Dry matter;
Plant ash ; Form of the ash elements ; Amount of ash in plants ;
Importance of ash elements ; Water culture ; Sand culture ; Occur-
rence and function of ash elements ; Potassium : Sodium ; Calcium ;

CONTENTS Xlll

Magnesium ; Aluminum ; Iron ; Phosphorus; Sulfur; Silicon; Chlo-
rin ; Kxperiments ; Problems. Pages 155-174.

CHAPTER XXIII

The Non-Nitrogenous Organic Compounds of Plants. — Organic
matter ; Non-nitrogenous and nitrogenous organic compounds ;
Classification of non-nitrogenous compounds ; Carbohydrates ;
General characteristics ; Cellulose ; Occurrence ; Physical proper-
ties ; Chemical properties ; Function and value ; Food value ;
Amount of cellulose in plants ; Crude fiber ; Starch ; Occurrence ;
Physical properties ; Chemical properties ; Function and value ;
Foo value of starch ; Amount of starch in plants ; Dextrin ; Struc-
tural formulas ; Sugar ; Classification of sugars ; Occurrence of
sucrose ; Physical and chemical properties of sucrose ; Milk-sugar ;
Maltose ; Inversion of sucrose ; Refining of sugar ; Occurrence of
dextrose ; Chemical and physical properties ; Levulose ; Miscel-
laneous sugars ; Optical properties of sugar ; Sugar-beets ; Food
value of sugar; Gums; Pentosans; Pectin bodies; Nitrogen-free
extract ; Fats ; Presence in plants ; Physical properties ; Chemical
composition ; Stearin ; Palmitin ; Olein ; Miscellaneous fats ; Saponi-
fication ; Fatty acids ; Waxes ; Food value of fat ; Amount of fat
in plants and foods ; Ether extract ; Organic acids ; Occurrence in
plants ; Tartaric acid ; Malic acid ; Succinic acid ; Oxalic acid ;
Citric acid ; Tannic acid ; Function and food value of the organic
acids ; Essential oils ; General properties ; Occurrence ; Chemical
composition and properties ; Essential oils of agricultural crops ;
Synthetic production of essential oils ; Amount of essential oils in
plants ; Food value ; Miscellaneous compounds in plants ; Relation-
ship of non-nitrogenous compounds of plants ; Food value of the
non -nitrogenous compounds ; Experiments and questions. Pages
175-213-

CHAPTER XXIV

The Nitrogenous Organic Compounds of Plants.— Amount of
nitrogenous matter in plants ; Different terms applied to nitroge-
nous compounds ; Complexity of composition ; Classification of
nitrogenous compounds ; Proteids ; General composition ; Oc-
currence ; Physical properties ; Chemical properties ; Classification

XIV CONTENTS

of proteids ; Albumins ; Globulins ; Albuminates ; Peptones and
proteoses ; Insoluble proteids ; Food value of proteids ; Amount in
plants ; Crude protein ; Albuminoids ; Composition ; Nuclein ;
Gelatin ; Mucin ; Elastin ; Food value of albuminoids ; Amides and
amines ; Composition and properties ; Formation and Occurrence
in plants ; Formation and occurrence of amides in animals ; Food
value ; Amount in foods ; Protein production and disintegration ;
Alkaloids ; General composition ; Plant alkaloids ; Animal alka-
loids ; Food value and production ; Mixed nitrogenous com-
pounds ; Lecithin ; Nitrogenous glucosides ; General relationship
of the nitrogenous organic compounds of foods ; Problems and ex-
periments. Pages 214-234.

CHAPTER XXV

Chemistry of Plant Growth. — Seeds ; Ash ; Non-nitrogenous com-
pounds; Nitrogenous compounds; Chemical changes during germi-
nation ; Change of starch to soluble forms ; Change of fats to
starch ; Change of insoluble proteids to soluble forms ; Germina-
tion of seeds and digestion of food compared ; Necessary condi-
tions for germination ; Heavy- and light-weight seeds ; Movement
of plant juices ; Joint action of chemical and physical agents; Poro-
sity of tissues ; Osmosis ; Chlorophyl and protoplasm ; Chemical
action in leaves of plants ; Production of chlorophyl ; Function ;
Production of organic matter ; Experiments. Pages 235-246.
CHAPTER XXVI

Composition of Plants at Different Stages of Growth. — Composi-
tion and stage of growth ; Assimilation of mineral food by the
wheat plant ; Assimilation of nitrogen by the wheat plant ; Clover ;
Rapidity of growth; Flax; Rapidity of growth; Maize (corn);
Importance ; Roots ; Stalks ; Leaves ; Tassel ; Husks ; Ripening
period. Pages 247-256.

CHAPTER XXVII

Factors which Influence the Composition and Feeding Value of
Crops. — Seed ; Soil ; Climate ; Stage of maturity ; Method of
preparation as food ; Improving the feeding value of forage crops.
Pages 257-262.

CONTENTS XV

CHAPTER XXVIII

Composition of Coarse Fodders. — Coarse fodders; Straw; Tim-
othy hay , Hay, similar to timothy ; Oat hay ; Hay, similar to oat
hay ; Bromus inermis ; Clover hay ; Alfalfa and fodders similar to
clover ; Rape ; Pasture grass ; Corn fodder and stover ; Silage.
Pages 263-272.

CHAPTER XXIX

Wheat. — Structure of kernel ; Proteids of vpheat ; Relation of
nitrogen in wheat to nitrogen content of flour ; Influence of ferti-
lizers upon composition of wheat ; Variations in composition of
wheat ; Storage in elevators ; Grading ; Composition of Unsound
wheat ; Composition of different varieties ; American and foreign
wheats ; Wheat as animal food ; As human food ; Experiments and
questions. Pages 273-288.

CHAPTER XXX

Maize (Indian Corn). — Structure of the kernel; Composition;
Proteids ; Nitrogenous and non-nitrogenous corn ; Varieties ;
Grading ; Corn products ; Corn as a food ; Experiments. Pages
289-295.

CHAPTER XXXI

Oats, Barley, Rye, Buckwheat, Rice, and Miscellaneous Seeds. —

Structure of the oat kernel ; Composition of oats ; Oats as human
and animal foods ; Barley ; Rye ; Rice ; Buckwheat ; Millet seed ;
Peas and beans ; Grading of grains ; Experiments. Pages 296-302.

CHAPTER XXXII
Mill and By-Products.— Sources ; Wheat by-products ; Wheat
bran ; Wheat shorts ; Wheat germ ; Wheat screenings ; Linseed
meal ; Cottonseed cake and meal ; Oat feed ; Gluten meal ; Malt
sprouts ; Miscellaneous by-products ; Inspection of feeding stuffs ;
Problems and experiments. Pages 303-311.

CHAPTER XXXIII
Roots, Tube^rs and Fruits. — General composition ; Potatoes; Car-
rots ; Parsnips ; Mangel wurzels ; Apples ; Oranges ; Lemons ; Straw-
berries ; Grapes ; Olives ; Dried fruits ; Miscellaneous fruits ; Food
value. Pages 312-317.

XVI CONTENTS

CHAPTER XXXIV
Fermentation. — Insoluble ferments ; Soluble ferments or enzymes ;
Aerobic and anaerobic ferments ; Conditions necessary for fermen-
tation ; Soil ferments ; Ferments in seeds ; Ferments in bread-
making ; Ferment action and food digestion ; Ferments and food
preservation ; Ferments in butter- and cheese-making ; Disease-
producing organisms ; Beneficial organisms ; Experiments. Pages
318-324-

CHAPTER XXXV

Chemistry of Digestion and Nutrition. — Digestion, a bio-chemicai
process ; Digestion experiments ; Caloric value of foods ; Available
energy of foods ; Net energy of foods ; Digestion of proteids ; Di-
gestion of the carbohydrates ; Digestion of fats ; Oxygen necessary
for digestion ; Factors influencing digestion ; Mechanical con-
dition ; Combination of foods ; Amount of food consumed ; Pala-
tability ; Individuality ; Miscellaneous factors influencing digesti-
bility ; Application of digestion coefficients ; Digestible nutrients
of foods ; Problems. Pages 325-342.

CHAPTER XXXVI
Rational Feeding of Animals. — Balanced rations ; A maintenance
ration ; Standard rations ; Food requirements of animals ; Food
supply at different stages of growth ; Food requirements of horses ;
Selection of food for horses ; Foods required for beef production ;
Selection of foods for beef production ; Food requirements of dairy
cows ; Selection of foods for dairy cows ; Food requirements of
swine ; Food requirements of sheep ; Calculation of balanced
rations ; Nutritive ratio ; Comparative cost and value ; Caloric value
of rations ; Sanitary conditions ; Problems. Pages 344-365.

CHAPTER XXXVII
Composition of Animal Bodies. — Water and dry matter ; Mineral
matter ; Fat ; Nitrogenous matter ; Proteids of meat ; Albumin ;
Myosin ; Syntonin ; Hemoglobin ; Insoluble Proteids ; Peptones ;
Keratin ; Albuminoids ; Gelatin ; Influence of food upon the com-
position of animal bodies ; Composition of human body. Pages
366-373-

CONTENTS XVU

CHAPTER XXXVIII
Rational Feeding of Men. — Similarity of the principles of human
and animal feeding ; Dietary standards ; Amount of food con-
sumed per day ; Calculating a balanced ration ; Comparative cost
and value of foods ; Factors influencing digestibility; Requisites of
a ration ; Dietary studies ; Chemical changes in the cooking of
foods ; Refuse and waste matters ; Loss of nutrients in the
preparation of foods ; Mineral matter in a ration ; Digestibility of
foods ; Digestibility of animal foods ; Digestibility of vegetable
foods; Relation of food to health; Tables of composition of human
foods. Pages 374-398.

CHAPTER I
Composition of Matter

I. Physical and Chemical Changes. — All substances
in nature are subject to change in form and composition.
At a low temperature, water is converted into ice, and by
the application of heat into steam. The three forms
which water may assume --solid, liquid, and vapor — are
simply different conditions in which it is capable of ex-
isting. When water is changed into steam or ice, noth-
ing is either added to or taken from the particles of water,
simply a change of form or a physical change takes place.
When, however, an electric current is passed through
water, the water is decomposed and two gases are pro-
duced. When such a change takes place, the water par-
ticles are subjected to a change in composition called a
chemical change.

Limestone may be pulverized until it is as fine as wheat
flour, and when examined with a microscope, each frag-
ment is in all respects like the original piece, except in
size. The crushing has resulted in simply dividing the
limestone into a large number of particles. If, however,
a piece of limestone is burned in a lime kiln, the product
is entirely different in its properties from the original
lime rock. When water is added to burned lime, it
slakes, heat is generated, and steam is given off, while,
when water is added to lime rock, no appreciable change
takes place.

Changes which affect the form but not the composition
of matter are known as physical changes. The produc-
tion of steam from water, the freezing of water, the pul-

2 AGRICULTURAL CHEMISTRY

verizing of limestone, and similar changes which do not
affect the composition of the material, are physical
changes. When milk sours, fruits decay, or wood is
burned, a different kind of change takes place. The
smallest particles of which each of the materials is com-
posed undergo a change in composition. The products
formed are entirely different in character from the origi-
nal substances. Such changes, which affect the identity
or individuality of a material, are chemical changes.

2. Physics is the science which concerns itself with the
changes which matter undergoes when the ultimate par- .
tides of a material retain their identity or individuality.

Animal and plant life are to a great extent dependent
upon the physical changes which take place in the soil.
Rain is the result of the action of physical agencies, as is
also the pulverization of rocks and soils. In all manu-
facturing operations, and as the result of all kinds of
manual labor, particularly upon the farm and in the
workshop, physical changes are continually taking place.

3. Chemistry is the science which deals with the
changes which matter undergoes when the ultimate par-

ticles lose their identity or individuality, and the prod-
ucts formed are entirely different from the original mate-

Chemical changes are continually taking place.
Plant growth and animal life are dependent largely upon
the chemical as well as the physical changes which take
place in the soil and in the air. Life processes are inti-
mately associated with chemical changes. Chemical and
physical changes are closely related ; a chemical change

COMPOSITION OF MATTER 3

is often dependent upon a physical change, and a physi-
cal change is, in turn, often dependent upon a chemical
change. A chemical change necessarily brings about a
physical change. While the sciences of chemistry and
physics are, to a certain extent, closely related, each
nevertheless deals with a different phase of change which
matter undergoes.

4. Indestructibility of Matter. — When either a chem-
ical or physical change takes place, no matter is destroyed
or produced. It is not possible either to create or destroy
matter. This is known as'tHe law of indestructibility of ^
matter.^

Whenever a chemical change takes place, the parts
which make up the substance are rearranged in a new and
different way, or they are combined with other materials.
When wood is burned, it is changed into gaseous prod-
ucts and ashes ; the materials which composed the wood
are not lost to nature, they simply assume a different
form. The law of indestructibility of matter is one of the
foundation principles of chemistry. It was believed, at
one time, that metals, as copper, could be changed into
gold, and other substances into different forms of matter.
After many centuries of experimenting, it was found
that this could not be done, and as the result, the law of
indestructibility of matter was established.

5. riolecules. — It is possible, by mechanical means, as
pulverizing, to reduce substances to a very fine state of
division, and it is believed that if this division could be
carried on by more refined methods, particles of mat-
ter could finally be obtained that would not be suscepti-

r
7

4 AGRICULTURAL CHEMISTRY

ble to farther division by purely physical methods. ^The
smallest particle of a material that can exist and have all
of the properties of the original material is called a mole-
'cule. Molecules, however, have never been separa.ted as_
individuals. All forms of matter are composed of mole-
cules. The proof that matter is composed of molecules
is founded upon the laws of physics. The reasons for
the acceptance of the molecular structure of matter can-
not be profitably undertaken by the student of elemen-
tary chemistry, but properly form a very important part
of advanced chemistry. The molecular structure of
matter has been sufficiently well established to warrant
the use of the term molecule by the student of elemen-
tary chemistry.

6. Atoms. — Whenever a chemical change takes place,
the molecule is changed in composition. When an elec-
tric current is passed through water, the molecules of
water are split up into simpler forms of matter. It is
evident that the molecule is not the simplest form of mat-
ter, and that while the molecule is the smallest part of a
substance, it is, in turn, made up of still smaller parts.
These parts of matter which make up a molecule are called
atoms, (An atom is the smallest part of an elementary
substance that can enter into combination to form a
molecule. Atoms never exist in nature in a free or un-
"combined state, but unite to form molecules, and mole-_
cules in turn unite to form masses. ^'
Jy^ . 7. Elements.-f-Tjie simplest forms of matter, as iron,
y^ copper and sulfur, from which it is impossible to extract
^^^ por obtain simpler bodies, are called elements. ) The ele-

COMPOSITION OF MATTER 5

ment is the simplest form in which matter can exist.
All substances found in nature, as plant and animal bod-
ies, rocks and soils, are composed of compounds which,
in turn, are composed of elements. There are about 74
of these elementary forms of matter, although only about
j^take any important part directly or indirectly, as far
as is known, in either plant or animal life processes.
There are a few substances found in nature in elementary
form, as iron, copper, gold, and sultufTbut most of the
elements are in combination with others, formin-g;-CiQia-
pounds. _

8. Compounds. — The substances found most abun-
dantly in nature are compounds. A compound is formed
by the chemical union of two or more elements_. ) All
compounds are made up of a definite amount, by weight,
of separate elements which unite according to the laws of
chemical combination. Water, for example, is a com-
pound made up of two elements, hydrogen and oxygen.
Sugar is a compound made up of three elements, hydrogen,
carbon, and oxygen. When elements unite to form a
compound, the elements lose their identity and the com-
pound that is produced has entirely different and distinct
chemical and physical properties from those of the ele-
ments of which it is composed.

9. Chemical Affinity. — The force or power which
causes elements to combine to form compounds is called
cEemical affinity, and about this comparatively little is
known. Whenever a compound is separated into its ele-
ments, chemical affinity or the force which holds the ele-
ments together is overcome. When elements com-

6 AGRICULTURAL CHEMISTRY

bine to form compounds, it is because of the chemical
afl&nity which the elements have for one another. Some
elements have a stronger affinit}- for certain elements than
for others.

ID. Mechanical flixtures. — When two or more sub-

stances mix, but fail to unite chemically, a mechanical
mixture is obtained. When iron and sulfur are mixe3^
a mechanical mixture is the result, and the iron and the
sulfur can, by purely physical methods, be separated.
If, however, a mixture of iron and sulfur is heated, a
chemical change takes place and it is impossible by physi-
cal methods, as by the use of a magnet or by solvents, to
separate the iron from the sulfur. Compounds as well
as elements may form mechanical mixtures.

11. Chemical Analysis and Synthesis. — Whenever a
substance or a compound is separated into simpler com-
pounds or elements, the process is called chemical analy-
sis. When only the kinds of elements or simpler com-
pounds are determined, the process is called qualitative
analysis. If the percentage amounts are determined, it
is called quantitative analysis. When elements or simpler
compounds are united, the process is called synthesis.
Synthesis and analj^sis are directly opposite processes.
When substances are produced in the laboratory from
simpler elements or compounds, it is called a synthetical
process. Many useful compounds are produced syntheti-
cally.

12. Summary. — Substances may undergo either phys-
ical or chemical changes. A physical change does not

COMPOSITION OF MATTER 7

destroy the identity or change the composition of the
molecule. When a chemical change occurs, the atoms
are combined in a different way and a new molecule is
produced. The molecule is the smallest particle of mat-
ter that can exist and retain its identity or individuality.
Physics and chemistry are closely related sciences, but
each deals with a different kind of change. Compounds
are composed of molecules, and molecules of atoms.
Atoms never exist free, but unite to form molecules. If
a substance contains in its molecule only atoms of one
kind, it is an element. If there are present atoms of
more than one kind, it is a compound. Life processes
are dependent largely upon the physical and chemical
changes continually taking place in nature.

CHAPTER II
Properties of Elements and Compounds
13, Physical Properties. — In order to determine the
value of any element or compound, a knowledge of its
chemical and physical properties is necessary, and it is
important that a clear idea be obtained as to what is
meant by the terms chemical and physical properties of
elements and compounds. Each element and compound
has its own characteristic properties, which are different
in a number of ways from those of other elements and
compounds. The physical properties of a substance in-
clude :

1. Form or state of the material, as solid, liquid, or
gas, which depends upon the temperature to which the
substance is subjected. Many substances which are solid
under ordinary conditions are, at higher temperatures,
converted into liquids or vapors ; and substances which
are gases are in turn converted into liquids and solids at
low temperature and under high pressure.

2. Weight or specific gravity. The weight or specific
gravity of a material depends upon its molecular struc-
ture and upon the character of its individual molecules.
Some of the elements and compounds have molecules of
greater weight than have others. Liquids and gases are
characterized as light or heavy according to their weight,
compared with some material taken as the standard.

3. Co^or. The color of a compound is a physical prop-
erty which is due to its chemical composition. Many of

ELEMENTS AND COMPOUNDS 9

the elements, as copper, silver, and gold, have character-
istic colors. Some compounds owe their value entirely to
their color, and are used for paints and dyes.

4. Odor and taste. The odor and taste of an element
or compound are physical properties which are character-
istic of the element or compound.

5. Electrical characteristics. Elements and compounds
have definite electrical properties. They are either good
or poor conductors of electricitj^ and offer a large or small
amount of resistance to the passing of an electric current.

The way in which a substance responds to pressure,
water, heat, and cold, depends upon its physical proper-
ties, and the physical properties in turn are modified by
these agencies.

In the study of the elements and their compounds, the
physical properties are also included because our knowl-
edge of chemistry would be incomplete without consider-
ing the physical as well as the chemical properties of
substances.

14. Chemical Properties.— In addition to the physical
properties, each element and compound has definite chem-
ical properties. This is because the molecules of the
different elements are unhke in character and some of the
elements and compounds are more readily affected by
chemical agencies than are others. The molecules of
compounds are made up of atoms of different kinds which
impart different properties to the molecule. Copper, for
example, has different chemical properties from gold. It
will dissolve more readily in acids, tarnish in the air, and
be acted upon more rapidly by other bodies than will

lO AGRICULTURAL CHEMISTRY

gold. When iron is exposed to moisture and air it rusts,
while aluminum is not readily affected by these agents.
This is because iron and aluminum have different chem-
ical properties. The chemical properties of a substance
include the wa}^ in which it combines or produces chem-
ical change when brought into contact with other ele-
ments or compounds. Some elements are characterized
as chemically active or inactive. An active element is
one that readily unites or combines with other elements,
while an inactivc-or passive element is one that does not
readily unite or combine. Some elements are active
under certain conditions and wath some of the elements,
and inactive under other conditions and with other ele-
ments. The various elements require different conditions
for producing chemical changes. In studying an element,
the way in which it deports itself in producing chemical
changes, the ability with which it combines with other
elements, and the products which are formed as the re-
sult of the chemical changes, are some of the more impor-
tant chemical properties considered.

The study of the chemical and physical properties of
elements and their compounds is important in many ways,
as the value of a substance depends entirely upon its
properties. In the growing and cultivation of crops, the
production, preparation, and the economic use of foods,
the treatment of diseases, and in all manufacturing opera-
tions, as the smelting and refining of metals, the chemical
and physical properties of the elements and their com-
pounds are constantly made use of.

15. Symbols of the Elements. — In the study of chem-

ELEMENTS AND COMPOUNDS

II

istry, a characteristic system of notation is used. The
name of an element, as oxygen, is not written in full, but
a symbol or sign, denoting the element is employed. In
the case of oxygen, the symbol is O. The symbol of an
element is either the first letter of the name of the ele-
ment, or the first with some characteristic letter, as CI
for chlorin. In some cases, the symbols are derived
from the Latin names of the elements, as Fe {Ferrujii)
for iron. By use, the student soon becomes familiar with
those symbols most commonly used.

Name. Symbol.

Aluminum Al

Antimony Sb

Arsenic As

Barium Ba

Bismuth Bi

Boron B

Bromin Br

Calcium Ca

Carbon C

Chlorin CI

Chromium .... Cr

Cobalt Co

Copper Cu

Fluorin F

Gold Au

Hydrogen H

lodin I

Iron P"e

Lead Pb

Lithium Li

Magnesium Mg

Manganese Mn

Mercury Hg

iproximate

Va-

Kind of

nic weight.

lence.

element.

27

3

Base-forming

120,5

3, 5

75

3, 5

137.5

2

Base-forming

208

3,5

II

3

Acid-forming

So

I

Acid-forming

40

2

Base-forming

12

2, 4

Acid-forming

35-5

I

Acid-forming

52

4,6

59

2, 4

Base-forming

64

I, 2

Base-forming

19

I

Acid-forming

197

3

Base-forming

127

I

Acid-forming

56

2, 3, 4

Base-forming

207

2, 4

Base-forming

7

I

Base-forming

24

2

Base-forming

55

2, 4, 6

200

If 2

Base-forming

12 AGRICULTURAL CHEMISTRY

Approximate Va- Kind of

Name. Symbol, atomic weight, leuce. element.

Nickel Ni 59 2,4 Base forming

Nitrogen N 14 3,5 Acid-forming

Oxygen O 16 2 Acid-forming

Phosphorus P 31 3,5 Acid-forming

Platinum Pt 195 4 Base-forming

Potassium K 39 i Base-forming

Silicon Si 28 4 Acid-forming

Silver Ag 108 i Base-forming

Sodium Na 23 i Base-forming

Sulfur S 32 2, 4 Acid-forming

Tin Sn 119 2,4 Base-forming

Zinc Zn 65.5 2 Base-forming

16. Formulas of Compounds. — Since compounds are
composed of elements, it is possible, by means of combi-
nation of symbols, to express the formula of a compound.
The formula of a compound denotes the number and
kinds of elements contained ; as, for water, the formula
H^O designates that the compound is composed of the
two elements hydrogen and oxygen ; and for sugar, the
formula C^^H^.fi^^ denotes that the compound is made up
of three elements, carbon, hydrogen, and oxygen. The
formula always expresses the composition. In the for-
mulas of compounds, figures are made use of, as 2 in H^O,
at the right of the H and partially below the line. In
this formula, the 2 indicates that there are two atoms of
H in the molecule. In the case of sugar, the figures used
mean that in one molecule of sugar there are 1 2 atoms of
C, 22 atoms of H, and 11 of O. The formula of a com-
pound alwaj's represents one molecule of the compound
unless .some figure is placed to the left of the formula, as
211^0. When placed in this position, the 2 designates

ELEMENTS AND COMPOUNDS 13

that there are two molecules of water. Figures placed to
the left of a formula and on the same line indicate the
number of molecules, while figures to the right of the in-
dividual element represent the number of atoms of ele-
ments in each molecule. Hence the formula of a com-
pound always designates the composition of the molecule,
and the number and kind of atoms contained. Farther
study of the formulas of compounds will show that addi-
tional facts, as composition by weight and volume, are
also represented.

Exercise. — Name the elements, the number of molecules, and
the number of atoms in each molecule in the following formulas :
NaCl, CaCl^, 2KCI, 2K,Sa, Al^Oa, sN^Oj, H,SO„ NaOH, HPO3. y^^^^

17. Atomic Weights. — An atom is the smallest part of
an element present in a molecule. Atoms have definite
properties, as weight. Hydrogen is the lightest material
_known. . An atom of hydrogen, or the smallest part of
hydrogen which can enter into chemical combination, is
considered as having a weight of i. The weight of the_
atom of any element is the number of times heavier that
atom is than hydrogen, which is the standard. Oxygen,
for example, has an atomic weight of 16, that is, an atom
of oxygen weighs 16 times as much as an atom of hydro-
gen. Carbon has an atomic weight of 12, that is, an
atom of carbon is 12 times as heavy as an atom of hydro-
gen. The way in which the atomic weights are obtained
cannot, at this stage of the work, be profitably considered.
Atomic weights are, however, obtained with a high de-
gree of accuracy, and while the individual atoms and
molecules are not susceptible, at the present time, to sep-

14 AGRICULTURAL CHEMISTRY

aration and weighing, the comparative weight, or the
number of times heavier or Hghter a definite number of
molecules is than a similar number of molecules, in other
form: of matter, can be accurately determined. While
the absolute weight of a molecule or atom cannot be_
determined, its comparative weight can be. When chlo-
rin, for example, combines with hydrogen, it is known
that 35.45 times as much, by weight, of chlorin as of
hydrogen has entered into combination. Hence the
smallest part by weight of chlorin which can combine,
must weigh at least 35.45 times as much as the weight of
the smallest particle of hydrogen which enters into com-
bination. The atomic weights of the more common ele-
ments are given in the table on page 1 1 .

18. Molecular Weights.— Since the molecules of com-
pounds are composed of a definite number of atoms of
elements, and each atom has a definite weight, it neces-
sarily follows that a molecule has a definite weight. In
the case of water, the formula H^O represents one mole-
cule of water, composed of two atoms of hydrogen and
one of oxygen. As the atoms have definite weights, the
weight of the molecule H^O is the sum of the weights of
the atoms in the molecule. Since hydrogen is taken as
the standard and weighs i , and there are two atoms of
hydrogen, and one atom of oxygen weighing 16, the
weight of the molecule will be 2 + 16 or 18 ; that is, the
molecule of water, H^O, is 18 times heavier than one
atom of hydrogen.

Exercise. — Compute the molecular weights of the compounds
given in the exercise following the formulas of the compounds,
Section 16.

ELEMENTS AND COMPOUNDS 1 5

19. Law of Definite Proportion. — A study of the com-
biuation of elements has shown that always when elements
unite to form compounds, a definite weight ot" each ele^
jiient enters into the composition. This is known as the
law of definite proportion . Chemical combination always
takes place between definite weights of the elements, and
a chemical compound always contains the same elements
in exactly the same proportion by weight. The law of
definite proportion is one of the foundation principles of
modern chemistry, and has enabled the chemist to deter-
mine the composition of bodies. This law is founded
upon facts independent of any hypothesis, and the accu-
racy of the law has been demonstrated by many investi-
gators.

The theories relating to the composition of matter, par-
ticularly to atoms and molecules, are in harmony with
this law of definite proportion. It is believed, since
chemical combination takes place between definite masses
of elements, it must also take place between the smallest
particles of the substances. Since the smallest particles
which enter into chemical composition are the atoms,
chemical combination must take place between the atoms.
The atoms all possess definite weights. Hence it can
readily be understood why chemical combination takes
place between definite weights of the elements. The
next step in the study of the composition of matter is the
way in which the elements combine, or the power of com-
bination ; this is known as valence.

20. Valence. — The valence._of , elements is the power
which an atom of one. element has of holding in chem-

1 6 AGRICULTURAL CHEMISTRY

ical combination a definite number of atoms of other ele-
ments. Carbon, for example, has the power of uniting"
with or holding in chemical combination four hydrogen
atoms ; carbon is said, therefore, to have a valence of 4.
Elements which have power to hold only one atom of hy-
drogen in combination are called monovalent. Hydro
gen is a monovalent element. Bivalent, trivalent, tetra-
valent, and pentavalent elements are those whose atoms
have the power of uniting with 2, 3, 4, and 5 atoms
of hydrogen or other monovalent elements. The valence
of an element is spoken of as its combining power. Some
of the elements have more than one valence. The va-
lences of some of the more common elements are given
on page 1 1 .

21. Combination of Elements. — The combination of
two elements to form compounds is always governed by
the valence of the elements. When calcium and chlorin
combine, the combination takes place in a definite way ;
calcium has a valence of 2 ; chlorin has a valence of i ;
hence, in order to make a chemical combination, it will
take one atom of Ca, having a valence of 2, to combine
with two atoms of CI, each CI atom having a valence of
I. CaClj is the formula. Calcium could not combine
with three atoms of chlorin, because compounds com-
posed of two elements are always formed according to the^
valence of the elements. The valence of calcium, 2, lim-
its the number of atoms of chlorin with which it can com-
bine. If one of the elements, as oxygen, has a valence
of 2, and the other element, as carbon, has a valence of
4, 2 atoms of oxygen, each atom having a valence of 2,

ELEMKNTS AND COMPOUNDS l7

will be required to combine with i atom of carbon, hav-
ing a valence of 4. The formula is COj. In the for-
mulas of compounds, the valences of the atoms uniting
are always balanced or satisfied.

When two elements combine, and one of them has an
odd valence, as phosphorus, which has a valence of 3,
two atoms of the element with the odd valence are always
required for combination. For example, two phosphorus
atoms, each having a valence of 3, making a total valence
of 6, require, in order to combine with O, whose valence
is 2, three atoms of O, which make the valence of 6. The
two atoms of phosphorus combine with the three atoms
of oxygen, making a balanced compound, and the va-
lences of the phosphorus and oxygen are satisfied. The
compound is P2O3.

Combine according to the lowest valence, the following
elements, and give the formulas of the compounds pro-
duced.

Zinc and oxygen ■C' V\ 0 Sulfur and oxygen S ^ k

Calcium and oxygen^^*^ Sodium and chlorin ^vJ^^t^n"
Tin and oxygen ^ViO Potassium and chlorin Y^^^

Iron and oxygen -f a, ^ Carbon and oxygen (/yO

Potassium and oxygen^ ^0 Phosphorus and oxygen ^
Silicon and oxygen <5 Vj 0 v Iron and sulfur , »,'^^
Potassium and sulfur \V iJ~~>
Manganese and sulfur \i .-■' ~^
Phosphorus and hydrogen^ \Sb
Calcium and chlorin ^io-^l^
Aluminum and oxygen uX'*'^
Phosphorus and oxygen \«vO
PrObletn i. — How much hydrogen is required to combine with 20
grams of O to form H^O ? When hydrogen and oxygen unite to
form water, the combination takes place according to valence, as

1 8 AGRICULTURAL CHEMISTRY

follows : 2 atoms of H + i atom of O equal i molecule of water,
or 2H + O =: HjO. An atom of O weighs i6 times as much as
an atom of H. Two atoms of H and i atom of O weigh i8 times as
much as an atom of H. The molecular weight of water is i8.
Sixteen of these i8 parts, by weight, are O, or 16/18 are oxygen,
which is 88.88 per cent.; 2/18, or 11. 12 per cent, being H. In the
production of water, H and O always unite in this proportion. If,
for example, 20 grams of O and 2 grams of H were brought to-
gether, only 16 grams of O would enter into chemical combination
with the 2 grams of H, and 4 grams of O would be left uncombined.
The amount of H required to combine with 20 grams of O would
be obtained from the following proportion, — 2 : 16 : : .ar : 20, or
x^ 2.5 grams of H.

Problem 2. — (i) Calculate the per cent, by weight of C and O in
CO3. (2) Calculate the per cent, of Fe and O in Fe-Ps. (3)
Calculate the per cent, of O in KClOj.

>t"^'J^/V

-v

Z

>,^

V

CHAPTER III
Laboratory Manipulation

22. Importance of Laboratory Practice. — Laboratory
practice is au essential part of the study of chemistry.
Many of the important facts and laws of chemistry are
capable of being demonstrated by the student, and the
laboratory practice assists in developing more perfect
ideas in regard to the composition of substances. The
hand, the eye, the nose, and, to a less extent, the ear,
are all called into use in the laboratory, and this results
in a balanced education of the senses. Neatness is abso-
lutely necessary for success in laboratory work. An ex-
periment performed in a slovenly way, with dirty and
poorly connected apparatus, and poor mechanical manip-
ulation, fails to give the right impression or results.

When laboratory work is in progress it should receive
the student's entire attention. The directions for the
experiments should be carefully followed. The appara-
tus should always be put together as directed, and be-
cause of the danger of accident, the student should never
take the risk of connecting apparatus in an original way,
or of using for the experiment, materials other than those
directed. The student should never attempt to experi-
ment for himself in combining chemicals.

23. Names and Uses of Apparatus. — The various
pieces of apparatus used in the experiments are shown in
Plates I and II. Number 23 shows the common Bunsen
burner, and at the right, the wing-top attachment, used

20 AGRICUIvTURAL CHEMISTRY

in bending glass tubes. Number 24, Plate II, is an iron
ring-stand with three rings, and No. 25 is a single clamp.
The iron stand with rings is used for supporting appara-
tus, particularly the sand-bath (19) in which is a thin
layer of sand. The evaporating dish (5), beaker (12),
and flask (26) are all supported in the various experi-
ments upon the sand-bath and iron ring-stand. In the
cutting of glass tubes and the perforation of corks, the
two files (i and 2) are employed. Test-tube (13) is used
extensively in the laboratory, and when heated it is sup-
ported in the test-tube clamp (18). This test-tube clamp
is held in the hand. The test tube is cleaned with the
test-tube brush (17) and when not in use is placed in the
test tube rack (14). When solutions are filtered, the
funnel (15) is used, and is supported in the wooden
stand (21). Substances are pulverized or mixed in the
mortar (16) which is supplied with a pestle. The vari-
ous gases, as oxygen, hydrogen, and nitrogen, are col-
lected in the small cylinder (10), and in some of the ex-
periments, the large cylinder (11) is used. The iron
spoon (8) is used for the ignition of substances. The
crucible tongs (3) are for handling pieces of apparatus
when hot. The other pieces of apparatus, Woulff bottle
(7), water-bath (4), tripod (22), Hessian crucible (20),
wide-mouthed bottle, (9), and the ground glass plate
with a hole, are used in various ways in the different ex-
periments. Glass rods, a thi.stle-tube, a pneumatic trough,
and small squares of plain glass complete the set of appa-
ratus. A few pieces, used only occasionally, are obtained
from the instructor at the time the experiments are per-
formed.

LABORATORY MANIPULATION

21

The student should take an inventory of his apparatus
as soon as assigned a place in the laboratory. In case
any of the pieces are broken or missing, the attention of
the instructor should be called to them. Always, at the
close of each day's work, the apparatus should be
cleaned, placed in the desk, and the desk locked. The
apparatus and desk should always be kept in a neat and
orderly condition. Untidiness is a frequent cause of
failure in laboratory work ; neatness and careful atten-
tion to details are necessary to success.

24. Cutting Glass Tubing.— Lay the glass tube on the
top of the desk or any flat surface. Draw a sharp three-
cornered file across it two or three times, always on the
same place at which it is to be broken, until a scratch .s
made through the annealed surface of the tubing. Take

Fig. I. — Breaking glass tubing.

the tube in the hands with fingers and a thumb on each
side of the scratch (see Fig. i). The scratch should be
nearly between and on the side opposite the thumbs.
Pull the hands tow^ard the body as if bending the tube,

22

AGRICULTURAL CHEMISTRY

and at the same time press outward with the thumbs.
This causes a square break of the tube. The cut ends of
the tubing should then be held in the outer portion of the
flame until the rough edges are annealed.

25. Bending Glass Tubing.— Place the wing-top at-
tachment on the burner. Hold the tube in the upper
part of the flame as shown in the illustration (Fig. 2),

Fig. 2.— Bending glass tubing.

and rotate so that all parts are heated alike. When the
tubing becomes red and readily yields, it can be bent in
almost any form desired, but if overheated it becomes too

soft and collapses. It is always
best to bend without removing
from the flame. A little prac-
tice with pieces of old tubing will
soon give the necessary experi-
ence. Avoid twisting or rapid bending of the tube.
Make all bends on the same plane and aim to make well
rounded joints as shown in Fig. 3.

26. Perforating Works. — Select a cork of suitable size
for the test-tube or flask used. New corks should always

Fig. 3.— Bent tube.

LABORATORY MANIPULATION 23

be rolled in the cork press. With the small pointed end
of the round file make a hole through the center of the
cork, or a little to one side if directed to do so. This
hole should be perpendicular to the surface of the cork.
In making a hole, the cork should be held in the left hand,
and the larger end should be placed against the edge of
the desk. The file should be held in the right hand, and
only enough pressure exerted to perforate the cork. By
means of the round end of the file, the opening thus made
is enlarged until the desired size is obtained. The hole
should be a suggestion smaller than
the tube it is to receive, which can be
inserted easily if well annealed and
wet. When inserting a tube in a
cork, never push the tubing toward
the palm of the hand, or use too much
pressure ; otherwise severe cuts may
be received from breaking of the glass.

Fig. 4.— Inserting glass

Hold the cork in the left hand as tube into cork,

shown in Fig. 4, and then with the right hand carefully
insert the tube.

27. Weighing. — In this work, the metric system of
weights and measures is employed, and it is taken for
granted that the student is familiar with the system ; if
he is not, he should review the subject as given in any
ordinary arithmetic.

Note. — I kilo =2.2046 lbs. (avoirdupois).
I oz. = 28.35 gms.
I lb. = 453.59 gms.
I liter = 1.05708 U. S. quart.
I inch = 2.54 centimeters.
I meter = 39.3808 inches.

24

AGRICULTURAL CHEMISTRY

The small balance used for weighing materials in these
experiments is shown in Fig. 5. In case 5 grams of a
material are to be weighed, prepare counterpoised papers,
about 3 by 4 inches in size ; that
is, tvA'o pieces of paper of exactly
the same size to be placed on op-
posite sides of the balance. If
they do not weigh alike, remove
small pieces of paper from the
heavier pan, until the needle
moves nearly as many divisions
on one side of the scale as on the
other. Then place, with the for-
ceps, the 5 gram weight on the
Fig. 5— Balance. right-hand pan of the balance.

Do not handle the weights with the fingers. By means of
the scoop or spoon provided for the purpose, add to the
paper in the left-hand pan of the balance, enough of the
material that is to be weighed to counterpoise the 5-gram
weight. If any of the substance has been spilled it should
be cleaned up at once. The weight should be replaced in
the tveight box and the forceps returned to their proper place.
If the weights are lost, a charge is made to cover the ex-
pense of their replacement. No substance except a piece
of metal, as copper or lead, should ever be placed in direct
contact with the balance pan. Liquids are never weighed,
but always measured. Too much care and neatness can-
not be exercised in weighing.

28. rieasuring Liquids. — For purposes of measuring,
cylinders or graduates are employed (Fig. 6). A large

LABORATORY MANIPULATION

25

n

i'-

test-tube, when filled with water, holds from 60 to 65 cc.
Take a measuring cylinder or graduate (Fig. 6), measure
out 5 cc. of water, and transfer to a large test-
tube. Note the quantity, and then pour it
out. Now draw water directly into the test-
tube until you have approximately the same
amount, then measure it. Repeat this opera-
tion until you can judge with a fair degree of
accuracy the part of a test-tube filled by 5 cc.
Then repeat the operation, using 10, 15, 20,
and 25 cc. portions, until the eye has become
reasonably familiar with these approximate
and relative amounts ; so that, if at any time
a graduate is not at hand, the amounts can be
estimated with the eye accurately enough for practical
purposes.

29. Obtaining Reagents from Bottles. — Take the bot-
tle from the shelf, remove
the stopper, holding it be-
tween the first and second
fingers of the right or left
hand (Fig. 7). Hold the
test-tube or vessel that is
to receive the reagent in
the other hand. Pour out
the liquid slowly until the
desired amount is obtained.

Because of danger of con-
Fig. 7. -Pouring liquid from bottle, taminating the reagents, it
is always better to pour the liquid slowly and secure the

26

AGRICULTURAL CHEMISTRY

right amount at first rather than to pour back from the
receiving vessel. Replace the test-tube in the stand or
receiver on the desk ; then, before inserting the stopper,
touch it to the neck of the bottle to catch the few drops
on the edge, to prevent them from streaking down the
sides of the bottle, and on to the shelf. Be sure to 7-eplace
the bottle on the shelf in its proper place. Much an-
noyance and delay is caused by not returning the bottles
to their proper places.

30. Filtering.— Place the funnel on the arm of the
wooden stand. Fold a filter-paper so as to make a semi-

Fig. 8.

Fig. 9.
Folding filter-paper.

Fig. 10.

circle (see Figs. 8 and 9). Fold the paper again,
forming a quadrant (Fig. 10). Then
open it as shown in Fig. 11.
Place the filter-paper in the funnel,
using a little water to make it ad-
here to the sides. Place a beaker
or cylinder under the funnel so as
to collect the filtrate, or liquid which
passes through the filter-paper (Fig.

12). Pour the material to be filtered into the filter-

Fig. II. — Folded filter-
paper.

LABORATORY MANIPULATION

27

paper in the funnel. Do not fill the filter too full. An
eighth of an inch or so should always be left between the
surface of the liquid and the edge
of the paper. The stem of the
funnel should always be left against
the side of the beaker or cylinder so
as to avoid spattering. The ma-
terial left on the filter-paper is
called the precipitate or residue.

31. Laboratory Note=book. —
Each student should keep a careful
record of his laboratory work. The
note-book should be complete and
should represent the student's in-
dividual work. With each experi-
ment a number of questions are
asked, and the record of the experi-
ment should embody the answers
to these questions. Do not make
short answers, as "yes" and "no,"
but make a complete statement,
giving an intelligent answ^er to the
question. Do not copy the laboratory directions into
your note-book, but state briefly and concisely, (i) what
the experiment is about, (2) the materials used, (3) the
apparatus employed, (4) what you have observed in ma-
king the experiment, (5) the chemical and other changes
that have taken place, and finally what the experiment
proves. In writing up the note-book, it is not necessary
to separate the topics, but all the questions should be

Fig. 12. — Filtering.

28 AGRICULTURAL CHEMISTRY

numbered and answered in the order asked. Write out
each experiment at the time it is performed ; and while
the work is in progress, watch it and think about it. Do
not leave or neglect an experiment. When the experi-
ments are performed as called for from day to day, the
labor of preparing the daily recitation is considerably
lessened, and less effort is required to obtain a clear idea
of the subject. The note-book should be kept in a neat
and orderly way. Careful attention should be given to
spelling, English, and punctuation. Always have the
note-book in condition for examination if the books are
called for without notice. The instructor will mark all
errors, and the student should correct these errors. A
note-book with errors that have been corrected, represent-
ing the student's individual work, is much to be preferred
to a note-book, copied from some other student, and hav-
ing but few^ errors. Each student has an individuality
which al\\ays marks his w'ork, and whenever copying of
experiments is resorted to, it is detected by the in-
structor. The student who copies from some one else
only cheats himself, and usually fails to pass his exam-
inations.

32. Breaking of Apparatus. — If due care is taken in
performing the experiments, there will be but little break-
age of apparatus. In case an accident occurs, clean up
the broken pieces at once and place them in the waste jar.
If a liquid is spilled, wipe it up with a sponge, using
plenty of water. If a strong acid is spilled, a little dilute
ammonia should be used in the final washing. No com-
bustible materials should be placed in the desk, and the

LABORATORY MANIPULATION 29

student should throw burned matches and splinters into
the receptacles provided for the purpose.

33. Care of Sinks and Plumbing.— Do not throw waste
matter of any description, as paper, glass, matches, etc.,
into the sinks. L,arge waste jars, for such materials, are
provided under every sink and elsewhere. Everything
liable to clog the drains must be thrown into these jars.
Liquids containing acids may be safely thrown into the
sinks, provided a stream of water is kept running at the
same time to dilute and wash out the acids. When acids
are poured into the sinks, care should be taken to prevent
spattering of the liquid, as severe burns are sometimes
received when the liquid is not properly poured from the
vessel. If directions are followed no accidents can occur.
Do not fill the sinks too full. The water should never be
allowed to come to within 2 inches of the top of the
sinks. If the sinks overflow they cause much damage to
the rooms below. Students who disregard the regula-
tions in regard to plumbing and the use of sinks, will be
held responsible and must pay for any damage caused by
carelessness or negligence.

34. How to Accomplishi the Best Results in tlie Lab-
oratory.— In order to accomplish the best results, the
student, while in the laboratory, should endeavor to use
his time profitably and economically. He should obtain
a clear idea of what he is to do, and then do it to the best
of his ability. If the experiment is not a success, repeat
the work. Never pass over an experiment ^that offers
difficulties in performing. Much valuable time can be
saved by a brief study of the day's work before going

30 AGRICULTURAL CHEMISTRY

into the laboratory. While the work is in progress, the
student should give it undivided attention, and make an
effort to learn as much as possible from the experiments
performed.

CHAPTER IV
Oxygen

35. Occurrence. —Oxygen is the most abundant element
in nature. About one-fourth of the air, by weight, is
free or uncombined oxygen. It enters into the composi-
tion of water, rocks, and minerals, and plant and animal
bodies. Seven-eighths of water and
one-half of the solid crust of the
earth are oxygen in combination with
other elements. Oxygen is also
present in all animal and plant tis-
sue, making up a large portion of
the weight of these bodies.

36. Preparation. — Oxygen can
be prepared from a number of ma-
terials, as oxid of mercury, oxid of
iron, and potassium chlorate. When
made in small amounts in the lab-
oratory, it is usually prepared by
heating potassium chlorate, a com-
pound composed of the elements
potassium, chlorin, and oxygen.
The oxygen is separated by means
of heat, the process being as follows:

Experiment i. — Anneal the end of a
piece of glass tubing, 2 1/2 or 3 feet long.
Make a bend nearly at right angles to the Fig- 13-
tube, about 3 inches from one end. Then make a
of 2 1/2 or 3 inches on the opposite end of the tube nearly at right

Delivery tube,
second bend

32

AGRICULTURAI. CHEMISTRY

angles, and in an opposite direction from the first bend (Fig. 13).
Fit to the test-tube a cork, perforated as directed in Section 26, and
insert the delivery tube. Fill the pneumatic trough nearly full of
water, and place in it the free end of the delivery tube (Fig. 14).
Weigh out 5 grams each of potassium chlorate (KCIO3) and man-

Fig. 14.— Preparation of oxygen. Pneumatic trough.

ganesedioxid (MnOj). Mix on a sheet of paper, and place the
mixture in a test-tube. See that the test-tube is perfectly dry, both
inside and out. Fill the cylinders with water, cover with glass
plates and place them inverted on the shelf of the pneumatic trough.
With a medium-sized flame, apply heat cautiously to the test-tube.
The flame should be moved from time to time, and not allowed to
strike just one part of the test-tube, otherwise the glass will melt,
and the test-tube collapse. As soon as bubbles of gas are given oflE
freely from the water, place the end of the delivery tube so that
the gas is collected in one of the cylinders. When a cylinder
is filled, cover it with one of the glass plates, while the mouth of
the cylinder is still under water. It can then be placed upright
upon the desk, and another cylinder filled with O. After collect-
ing three or four cylinders of gas, remove the end of the delivery
tube from the water, and then remove the flame. Do not remove
the flame while the end of the delivery tube is under water, or a
vacuum will be formed, and the water will rush back into the test-
tube. Tests should be made with the O as follows :

(i) Light a splinter and place it for a moment in one of the cyl-
inders of oxygen (see Fig. 15) ; remove it ; extinguish the flame,

OXYGEN

33

and while the splinter is still glowing, thrust it into the cylinder
again. Observe the result in each case. (2) Put a small piece of
sulfur, a little larger than a grain of wheat, into the iron or defla-
gration spoon ; ignite in the flame, and
then thrust into another cylinder of O.
Observe the result. (3) Take a piece of
bright fine iron wire or watch-spring, and
make it into a spiral with a loop at one
end. Warm the wire by holding it near
the flame, then hold the loop for an in-
stant in the flame and dip it into some
sulfur which has been placed on a piece
of paper. Hold again in the flame for a
moment and then place at once in the
third cylinder of O. In order to insure
the success of this experiment, the wire
should be very fine, free from rust, and
held in the flame only long enough to
start ignition, and then placed in the
cylinder.

Questions, (i) Where does the O in the cylinder come from ?
(2) What caused it to separate from the compound ? (3) What is
the appearance of O ? (4) Compared with air, is it a light or heavy
gas ? (5) What caused the splinter to burn and to rekindle ? (6)
What product was formed when the splinter was burned? (7)
What caused the sulfur to burn ? (8) What product was formed
when the S was burned ? (9) Why do these materials burn differ-
ently in O than in air? (10) What caused the iron to burn, and
what was formed ? ( 1 1 ) Is O combustible ? ( 12 ) Is O a supporter
of combustion ? (13) What compounds are always formed by the
union of O with an element? (14) Give the properties and char-
acteristics of O as observed from this experiment.

The oxygen in potassium chlorate is not held in firm chemical
combination, and when the substance is heated, first a portion, and
finally all of the oxygen is given off. The manganese dioxid is
used because of its physical action upon the potassium chlorate,

Fig. 15. — Testing oxygen
with burning splinter.

34

AGRICULTURAL CHEMISTRY

enabling the oxygen to be given off more easily. The change
which takes place is exj^ressed by the equation : KCIO3 = KCl + 3O.
The products of the reaction are potassium chlorid and oxygen.

Fig. 16. — Preparation of oxygen, using sink in place of pneumatic trough.
The oxygen is collected in the cylinders, while the potassium chlo-
rid remains with the manganese dioxid in the test-tube.

37. Properties of Oxygen. — Physically considered,
oxygen is a colorless, odorless, and tasteless gas, about
16 times as heavy as hydrogen. It is slightly soluble in
water, and, when subjected to a low temperature and a
high pressure, it is liquefied. Chemically, oxygen unites
with all common elements to form oxids. It is not com-
bustible, but is a supporter of combustion. When the
burning splinter was thrust into the cylinder of oxygen,
the carbon and hydrogen of the wood united with the
oxygen in the cylinder, forming carbon dioxid and water.
When substances unite with oxygen they are oxidized,
that is, oxygen is added to the material. An oxid is a
compound of oxygen and any other element. When sul-
fur is burned, it unites with oxygen, forming sulfur di-

OXYGEN 35

oxid, SOj. Other elements, as phosphorus and iron also
unite with oxygen, forming oxids. Different elements
unite with oxygen at different temperatures. Phosphorus
and sulfur combine with oxygen at a comparatively low
temperature, while carbon and iron require a higher tem-
perature. The sulfur and the splinter of w^ood burned
more brilliantly in the oxygen than in the air because air
is diluted with other gases and elements and is not pure
oxygen. Oxygen is more active at a high than at a low
temperature.

The oxidation of some of the elements and compounds
results in the production of light and heat ; this is com-
monly called combustion. Oxygen forms stable com-
pounds with many of the elements. It has such affinity
for some elements, as aluminum and carbon, that it is
separated from them with difficulty. With other ele-
ments it forms less stable compounds. When a substance
contains oxygen, it does not necessarily follow that it is
combustible, because it may be the product of combus-
tion as carbon dioxid or sulfur dioxid. When an ele-
ment, as oxygen, enters into chemical combination, it
loses its identity or individuality as an element. The
oxygen that is present in the minerals forming the crust
of the earth, and in plant and animal tissues, is not free
but combined with other elements.

38. Importance. — Oxygen takes an important part in
life affairs, and is necessary to the existence of plant and
animal bodies. The combustion of wood, coal, and other
fuel is due to the oxygen of the air. The production of
heat in the body is due to the oxidation of food, and many

36 AGRICULTURAL CHEMISTRY

of the chemical changes which take place in the soil are
dependent upon this element. Because of its wide distri-
bution in nature, it is not given such economic considera-
tion as are other elements, but it is one of the most im-
portant, and is as necessary for life as other food.

Problem i. — How many pounds of oxygen are required to com-
bine with 25 pounds of pure carbon ? When carbon is burned, i
part of C (called an atom) unites with 2 parts of O (2 atoms of O)
to form the compound CO,. This is expressed by the equation
C + 2O = CO2. The atomic or least combining weight of carbon is
12 and of O is 16; one part by weight of C weighing 12 unites with
2 parts by weight of O, each part weighing 16 ; or 12 parts by
weight of C unite with 32 parts by weight of O. If the parts are
designated pounds then 25 pounds of C will require proportionally
as much O asdo 12 pounds of C. This amount can be determined
by a simple proportion.

C : O : : C :0
12 : 32 : : 25 : .r.
By solving this proportion, x, or the required amount of O to com-
bine with 25 pounds of C, is found to be 66 23.

In the solving of chemical problems some of the most
common errors are : ( i ) Failure to write properly the
formulas of the compounds used, or the equation repre-
senting the chemical reaction that takes place. This
error causes the wrong number of parts of elements or
compounds to be taken in the proportion. (2) Failure
to make proper use of the combining weights of the ele-
ments. (3) Failure to combine properly the weights so
as to form a true proportion. It should be remembered
that after the writing of the equation and weights, the
problem becomes simply one of arithmetic.

Problem 2. — How many pounds of CO^ are produced when 25
pounds of carbon are burned ?

Problem j. — How many pounds of carbon are necessary to com-
bine with 25 pounds of O in forming COj ?

CHAPTER V
Hydrogen

39. Occurrence. — Hydrogen is found in nature in com-
bination with other elements, entering into the composi-
tion of water, animal and plant tissues, and some min-
erals. It is never found in a free state, except as given
off in traces with volcanic gases. Hydrogen is also found
in all acids and many other compounds.

40. Preparation. — In the laboratory, hydrogen is usu-
ally prepared by treating a metal with an acid, which
contains hydrogen ; the metal replaces the hydrogen of
the acid and the hydrogen is then liberated as a free gas.
"When zinc and hydrochloric acid are employed, the re-
action which takes place is as follows : Zn + 2HCI =
ZnClj + 2H. Two molecules of hydrochloric acid are
required in the reaction because zinc has a valence of 2,
and whenever zinc enters into chemical combination, it
must take the place of two monovalent atoms. The
compound, ZnClj, zinc chlorid, contains one atom of zinc
and two atoms of chloriu.

Experiment 2. — Arrange the apparatus as shown in Fig.
17. Use the small two-necked Woulff bottle, and in one of the
necks insert a tight-fitting cork with a thistle tube. In the
other neck insert a cork carrying a delivery tube. Place about
20 grams of zinc, Zn, and 25 cc. of water in the Woulff bottle.
The thistle tube should pass below the surface of the water to
prevent the escape of gas. Fill two or three cylinders with
water for collecting the gas. The corks carrying the delivery
tube and the thistle tube should fit tightly, otherwise the H is

38

AGRICULTURAL CHEMISTRY

easily lost. When all is ready, add, through the thistle tube,
about 15 CO. concentrated hydrochloric acid (HCl), and then
sufficient water to carry the acid out of the trap of the thistle
tube. Do not apply any heat whatever. Do not collect any gas
until the generator has been going for about two minutes, and do

Fig. 17. — Apparatus for preparation of hj-drogen.
not attempt to light the gas as it issues from the generator. Col-
lect one or two cylinders of gas, adding more acid if necessary,
always keeping the cylinders covered, mouth downward, because
H is a light gas, and will readily escape if the cylinders are
placed right side up.

When working with hydrogen in the laboratory, the
student should always exercise care, because mixtures of
hydrogen and oxygen are very explosive. Only a spark
or a near-by flame is necessary to bring about an explo-
sion.

Make the following test with hydrogen: Thrust a burn-
ing splinter into the mouth of the cylinder of hydrogen,
as shown in Fig. 18.

Questions, (i) What is the color ofH? (2) Odor? (3) Is
it a light or heavy gas? (4) Does it support combustion ? (5)

HYDROGEN

39

Is it combustible? (6) What is formed when H is burned?
(7) How do you know that this product is formed ? (8) From
what compound was the H obtained ? (9) What caused the H
to be liberated from this compound ? (10) Why are mixtures of

Fig. 18. — Thrusting burning splinter into hydrogen.

H and O very explosive? (11) What other acids could be used
in the preparation of H ? (12) What other metals could be used
in the preparation of H ? (13) Give the equation for the reac-
tion of the Zn and HCl. (14) What do these tests prove in re-
gard to the character and properties of the element H ?

41. Properties. — Physically, hydrogen is characterized
as a colorless, odorless, and tasteless gas. It is the
lightest in weight of any of the elements, and for that
reason is taken as the standard for the atomic weights.
At a low temperature, and under pressure, hydrogen can

40

AGRICULTURAL CHEMISTRY

be liquefied; with greater difficulty, however, than any
other element. Hydrogen is 14.43 times lighter than air.
A liter of hydrogen, under standard conditions of tempera-
ture and pressure, weighs 0.08961 gram. Chemically,
hydrogen is characterized as combustible, but not a sup-
porter of combustion. It readily combines
with many other elements, particularly oxy-
gen, with which it forms water. When
hydrogen and oxygen unite to form water,
a reaction takes place which causes a
contraction in volume.
Two volumes of hy-
drogen and one vol-
ume of oxygen unite
to produce tw\o vol-
umes of water-vapor or
steam. When hydro-
gen and oxygen unite,
there is always an ex-
plosion, due to coutrac-

Fig. 19.— Preparation of hydrogen, using a tioU in VOlumC. That
wide-mouthed bottle and sink in place of
a Woulff bottle and pneumatic trough, water IS produCCd whcU

hydrogen is burned, can be demonstrated by placing a dry
test-tube over a flame of hydrogen. The interior of the
test-tube will become covered with moisture. Hj^drogen
does not unite with all elements as readily as does ox5'gen.
When hydrogen is burned, the flame is nearly colorless be-
cause the combustion is complete, and there are in the
flame no solid particles heated to incandescence. Hydro-
gen produces an exceedingly hot flame, and, when mixed

HYDROGEN 4I

with oxygen in the right proportion, as in the oxyhydro-
gen blowpipe, a high temperature is secured.

42. Importance. — Hydrogen is one of the essential ele-
ments for the formation of compounds present in plant
and animal tissues, but because of its extreme lightness
it never makes up a large portion by weight of a mate-
rial. As a free element, it takes no part in life processes,
but when combined with water, and in other forms, as in
food materials where it is united with carbon and oxy-
gen, it forms an essential part of compounds which are
of much importance for animal and plant life.

Problem i. — How many pounds of H will 100 pounds of Zn
liberate when it is acted upon by HjSO^?

Problem 2. — How much ZnClj is formed when 100 pounds of
Zu are acted upon by HCl ?

CHAPTER VI
Nitrogen

43. Occurrence. — Nitrogen occurs abundantly in a free

state in the air, nearly four- fifths by weight being uncom-
bined nitrogen. It also forms a part of some of the com-
pounds which make up animal and plant tissues, where
it is in chemical combination with carbon, hydrogen, and
oxygen. Nitrogen is present also in the soil, forming a
part of the decaying organic matter ; it is one of the ele-
ments of ammonia gas and ammonium compounds, and is
present in combination with other elements, as in nitrates.

44. Preparation. — Nitrogen is usually prepared from
air by removing the oxygen with which it forms a me-
chanical mixture. Since air is composed of both oxygen
and nitrogen, if the oxygen in a given volume of air, as
in a cylinder, is chemically united with phosphorus or
carbon, forming soluble products, there is a residue of
nitrogen left in the cylinder. Nitrogen produced in this
way is not pure, but contains traces of other elements and
compounds. For experimental purposes, it may, how-
ever, be considered as nitrogen. Nitrogen can also be
produced from its compounds, as by the removal of the
hydrogen from ammonia gas. The method of prepara-
tion in the laboratory is as follows :

Experiment j. — Insert a long pin through the center of a
large flat cork. Fasten a short piece of caudle to the cork by
means of the pin. Nearly fill the pneumatic trough with water.
Light the candle and float it upon the surface of the water. In-
vert the large cylinder over the candle, having the mouth of the

NITROGEN

43

cylinder just below tlie surface of the water as shown in Fig.
20. After the candle is extinguished , remove it by thrusting the
hand through the water into the cylinder without admittingany

Fig. 20, — Preparation of nitrogen.
air. While still under water, cover the cylinder with a glass plate
and remove from the trough. Then make the following tests :

(i) Insert a burning splinter into the cylinder of N. Observe
the result. (2) Place a little sulfur in the deflagration spoon,
ignite, and insert in the cylinder of N. Observe the result.
(3) With a ruler, measure the height of the cylinder and the
amount of water left in the cylinder.

Questions, (i) What is the color of N? (2)Odor? (3) Com-
pared with air is it a heavy or light gas? (4) Is it combustible?
(5) Does N support combustion ? (6) Is N an active element ?
(7) What portion of the cylinder is filled with water in the
preparation of N ? (8) What portion of the cylinder is filled
with N ? (9) What portion of the cylinder did the O occupy ?
(10) What becomes of the products of the combustion of the
candle? (11) What do these experiments prove in regard to
the element N ? (12) Complete the following table :

Name of Combin- Com bus- Supporter of Where

element. Symbol, ing wt. Color. Taste. Odor, tible. combustion, found.

Oxygen

Nitrogen

Hydrogen

When the candle is burned, the oxygen of the air in the cyl-

44 AGRICULTURAL CHEMISTRY

inder unites with the carbon and hydrogen from the candle and
forms carbon dioxid and water. The COj is soluble in water,
and the gas that is left is mainly nitrogen. The com-
bination of the oxygen with the carbon causes a partial vacuum
to form, and this results in the water rising in the cylinder. If
great care is taken in performing the experiment, it will be found
that the water will fill about one-fifth of the volume of the cylin-
der, occupying the space of the oxygen which has been com-
bined with carbon. When all of the oxygen in the cylinder is
combined with the carbon, the candle is extinguished because of
lack of oxygen for combustion.

45. Properties of Nitrogen. — In general, the physical
properties of nitrogen, except weight, are somewhat like
those of hydrogen and oxygen, inasmuch as when pure,
it is colorless, tasteless, and odorless. It is about 14
times as heavy as hydrogen, and only slightly soluble in
water. At a low temperature and under pressure, it is
liquefied, and at a still lower temperature and under higher
pressure, it is solidified.

Chemically, nitrogen is unlike either hydrogen or oxy-
gen. It is an inactive gas; it is neither combustible nor
a supporter of combustion. When in the free state, it is
one of the most inactive of all the elements, and will com-
bine directly with only a few. When nitrogen enters into
combination with other elements, particularly with car-
bon and hydrogen, forming the organic compounds, it
has a tendency to make a weak link in the combination,
and will readily split off and form simpler products. In
the air, it .serves the purpose of diluting the oxygen. No
other element could perform this function as well as ni-
trogen. If the air were composed of pure oxygen, all
combustion would be carried on in a rapid and wasteful

NITROGEN 45

way. Nitrogen is not a poisonous gas, but if an animal
were compelled to breathe pure nitrogen, it would die
because of the lack of oxygen. Some of the compounds
of nitrogen decompose with violence, causing explosions.
Nearly all of the explosives, as gunpowder, nitroglycerin,
and guncotton, are compounds of nitrogen.

46. Importance. — The compounds of nitrogen take an
important part in animal and plant life. In combination
with carbon, hydrogen, and other elements, it forms the
nitrogenous compounds present in plant and animal bod-
ies. These compounds are called the organic nitrogenous
compounds because they are capable of undergoing com-
bustion, and produce volatile and gaseous products when
burned.

In the study of the chemistry of foods, and of soils and
fertilizers, the element nitrogen is given a prominent
place. This is because it is one of the most expensive
elements in commercial fertilizers, and foods which
contain the nitrogenous compounds are the most ex-
pensive. Although nitrogen is found abundantly in the
air, it is made use of as a plant food in an indirect way by
only a limited number of plants. Nitrogen forms a large
number of important compounds, as ammonia, nitrates,
nitrites, amids, and the complex organic compounds, pro-
teids. Some of these compounds will be studied more in
detail in future chapters. To the agricultural student,
nitrogen is one of the most important elements because of
the role which it plays in plant and animal economy.

problem i. — Calculate the per cent, of N in NaNO-.
Problem. 2. — Calculate the per cent, of N in NH;,.
Problem j. — Calculate the per cent, of N in (NH4),^S04.

CHAPTER VII
Carbon

47. Occurrence. — Carbon is found in the free state
only in limited amounts, but is present in nature mainly
in combination with other elements. With the mineral
elements and oxygen, it forms carbonates, such as calcium
carbonate or limestone. With hydrogen and oxygen, and a
few other elements, it forms a large number of compounds
of which plant and animal tissues are composed. All sub-
stances which char or blacken when burned contain this
element in combination. Diamonds, coal, and graphite
are forms of carbon in various degrees of purity. With
oxygen, it is present in the air in small amounts as carbon
dioxid. About half of the dry substance of wood and
animal tissue is carbon. It occurs in nature in a great
variety of forms.

48. Preparation. — In the form of charcoal, it can be
prepared from wood, by the application of heat in the ab-
sence of air or oxygen, when a change known as destruc-
tive distillation takes place. The hydrogen, oxygen, and
nitrogen are expelled, while the black mass of impure car-
bon and mineral matter is left. In the preparation of
charcoal, the wood is piled and burned in suitable pits,
which, after the combustion is well started, are covered
with turf to protect the burning mass from the air. Char-
coal can be produced on a small scale in the laboratory
in the following manner :

Experiment 4. — Place two or three small pieces of wood in a

CARBON

47

Hessian crucible, and cover with sand. Heat the crucible until
smoking ceases (see Fig. 21). Remove and examine the charcoal.

Qtiestiotis. ( I ) What are the principal elements present in wood?
(2) What becomes of these various elements when the material is
heated? (3) Why was the sand used in this ex-
periment ? (4) What becomes of the ash or mineral
matter in the process of charcoal-making? (5)
What is charcoal, and of what element is it prin-
cipally composed? (6) Does charcoal have a crys-
talline structure ? (7) What would be the result if
sand were not used in the experiment ? (8) Give
the equation for the combustion of carbon. (9)
How can charcoal be made on a large scale ?

Particles of carbon can also be obtained from a
gas, candle, or lamp flame, by holding a piece of
cold porcelain a little above the flame. Carbon, in
the form of soot, is deposited in chimneys when
fuel is burned with a poor draft. When combus-
tion is complete, the carbon is oxidized, forming

carbon dioxid. If a fire gives off a large amount Fig. 21.— Prepara-

<• ^ -u! 1 1 ii t^ • , tion of charcoal.

01 dense black smoke, the carbon is not com-
pletely oxidized, and consequently a loss of fuel value occurs.

49. Properties. — Carbon is foitnd in three forms in na-
ture : as diamond, graphite, and amorphous carbon.
The diamond is a pure form of crystalHzed carbon. It is
capable of being burned the same as any other form of
the element, and produces carbon dioxid. Diamonds of
small size can be produced artificially by the cooling of
graphite from molten iron. Graphite is also a crystalline
form of carbon, but the crystals are of different shape and
color from diamonds. It is soft, and is used quite exten-
sively as a lubricant. As it does not burn as readily as other
forms of carbon, it is used frequently for making cruci-

48 AGRICULTURAL CHEMISTRY

bles and for the linings of furnaces. It is a natural prod'
uct and is also produced artificially b}- dissolving carbon
in iron. There are a great many uncrystallized or amor-
phous forms of carbon, as lignite and soft coal, lampblack,
and charcoal.

50. Coal. — All of the conditions under which coal has
been produced are not known. It is supposed to be the
result of the joint action of heat and pressure upon pre-
historic forms of vegetation. Hard or anthracite coal is
the purest form known, and yields the smallest amount
of ash and unoxidized volatile products. Bituminous or
soft coal is less pure as a larger amount of the carbon is
present in chemical combination with the other elements,
and when burned, the carbon is not as completely oxi-
dized under ordinary conditions as is that of hard coal.
Coal may contain a number of impurities, as sulfur and
mineral matter. Cannel coal is a variety which contains
a large amount of mineral oils.

Lignite is vegetable matter which has only partially
undergone the coal-forming process. It is less pure than
soft coal, and is supposed to be an intermediate stage
in the formation. Peat is vegetable matter which has
undergone chemical changes under water. It is less pure
than lignite.

51. Allotropism. — An element which has the power to
take on so many different physical forms as has carbon
is called an allotropic element. Only a few elements have
the properties of allotropism,

52. Carbon as a Reducing Agent. — Carbon is used
extensively for the reduction of minerals. The action of

CARBON 49

carbon as a reducing agent may be observed from the fol-
lowing experiment ;

Experiment j. — Mix thoroughly 2 or 3 grams of copper
oxid (CuO) and an equal bulk of charcoal (animal charcoal).
Place the mixture in a small test-tube and apply heat. Observe the
result.

Questiojis. ( I ) What is the bright red material produced in the
test-tube? (2) What was the source of this material? (3) What
caused the O to be separated from this compound ? (4) What did
it unite with? (5) W^hat was formed as the product ? (6) Write
the reaction. (7) Why is carbon called a reducing agent? (8)
What kind of an agent would CuO be called? (9) Why is carbon
useful in separating minerals from their ores ?

When carbon acts as a reducing agent, it unites with or abstracts
the oxygen from the material reduced, forming COj. The process
is called reduction because the oxygen is abstracted. When oxy-
gen is added to a material, the process is just reversed, and is called
oxidation. When reduction takes place, oxygen is abstracted from
a material. When oxidation takes place, oxygen is added.

53. Combustion. — From the facts given in regard to
oxygen and carbon, it is evident that combustion, in the
ordinary sense, is simply the union of carbon with oxy-
gen, and, as a result, light and heat are given off. If the
process is a slow one, and heat without light is evolved,
slow oxidation takes place. An example of slow oxida-
tion is the rusting of metals. In slow oxidation, the total
amount of heat evolved is the same as if the material un-
derwent direct combustion. The regulation of drafts
in stoves to influence the combustion of fuel so as to ob-
tain the largest amount of heat, is based upon the simple
laws of the combustion of carbon.

A candle or gas flame well illustrates the laws of com-

50

AGRICULTURAI. CHEMISTRY

^:^^SaHc.^§Ssi-<

bustion. The outer portion of the flame is a non-lumi-
nous envelope of gases undergoing perfect combustion;
within this is a layer of gases undergoing partial combus-
tion, and constituting the light-giving part of the flame ;
while in the center is a zone which is more perfectly cut
off from the supply of air, and little or no combustion is
taking place. The combustion of a gas or candle flame
can be studied from the following experiment :

Experiment 6. — Structure of the flame. Unscrew the top
of a Bunsen burner and make a drawing showing how the burner

works, and the workings
of the orifices at the bot-
tom of the burner. Re-
place the parts of the
burner, open the air-holes
at the base, and light the
gas. Hold a sheet of paper
back of the flame and try
to distinguish the three
parts : { I ) the outer non -
luminous envelope of per-
fect combustion ; (2) the
inner luminous zone of
partial combustion ; (3)
the central blue cone of
unburned gas. Make a drawing of the flame. Press a piece of card-
board or paper down upon the flame for an instant and remove it
before it takes fire. Observe the result. Hold a piece of wire close
to the burner and observe that at first the wire does not become red
at the center of the flame. Thrust the head of a match into the
center of the flame for an instant and then remove it. If this is
done quickly, the match can be removed before combustion takes
place. Place a piece of wire gauze above the flame as shown in Fig.
23.' Observe the result. Extinguish the gas. Hold the wire gauze

Fig. 22. — Combustion.

CARBON

51

Fig. 23.— Combus-
tion.

about an inch above the burner, then light the gas above the gauze
(Fig. 22).

Questions. ( i ) Why was a charred circle formed when the piece
of paper was pressed down upon the flame ? (2) Why did the wire

. first redden near the outer

,4^^^^^3^^-~ '^ ' portions of the flame and not

\l'] at the center? (3) Why did

the flame refuse to burn
above the wire gauze, when
the gauze was pressed down upon the flame?
(4) When the gas was lighted above the gauze,
why did it refuse to burn below ? (5) What is
kindling temperature ? (6) What are the three
conditions necessary for combustion? (7) What
condition was lacking when the gauze was
placed in the flame ? (8) Why does a flame give
light when the air is excluded from the burner,
and give but little light when the air vent is open ? (9) Does the
amount of light which a flame produces indicate the amount of heat
produced? Why ? (10) What causes a flame to give light ? (11)
Why do some materials, when burned, produce more flame than
others? (12) What is spontaneous combustion? (13 ) Explain how
it is possible for clover or fodder to undergo spontaneous combus-
tion in a barn. (14) Wliat can be done to prevent spontaneous
combustion? (15) Carbon, when burned, produces heat; limestone,
CaCOg, contains carbon ; why is it not possible to use limestone for
fuel?

54. Spontaneous Combustion. — In order for a sub-
stance to undergo combustion, it is not necessary for a
match or flame to be applied to the material. As soon as
a substance is heated to its kindling temperature, that is,
the temperature at which it unites with oxygen, if in the
presence of air, combustion takes place, called spontaneous
combustion. Clover, when stored in the mow in a damp

52 AGRICULTURAL CHEMISTRY

condition, may undergo spontaneous combustion. The
fermentation which takes place produces combustible
gases which, at suitable temperature, ignite;
the burning gases, in turn, ignite the carbon
of the material. Substances containing a
great deal of oil and materials of low kindling
temperature, as carbon bisulfid, phosphorus
and sulfur, under suitable conditions of tem-
perature and air, readily undergo spontaneous

Fi?. 24— Candle COmbuStioU.
flame. 3. Non-
luminous cone. In case of fire, the laws governmg combus-

4. lyUminous

line. 5,6. Outer tiou should bc taken advantage of. If the

non-luinin ou s rr 1 1 r •

envelope. fire is a Small one, cut off the supply of air,

and the fire is extinguished. This can be accomplished
by the use of sand, wet blankets, or any material that
will cut off the supply of air. In order for spontaneous
combustion to take place, there must be (i) a combusti-
ble substance, which (2) is heated to a suitable tempera-
ture, and (3) in the presence of air.

55. Carbon a Decolorizer and Deodorizer. — Wood and
animal charcoal have the power of absorbing gases and
some coloring materials from solutions. In the manu-
facture of sugar, some of the impurities are removed by
bone-black or animal charcoal filters, and in purifying
water, charcoal filters are often used. The power of car-
bon to abstract gases and coloring-matter is largely a
physical property. In the soil, the carbon compounds de-
cay and produce humus, which has some of the physical
properties of charcoal to absorb gases and soluble bod-
ies.

CARBON

53

Experiment j. — Place iu a cylinder two grams of auimal
charcoal, and about i cc. cochineal solution diluted with lo cc.
water. Cover the cylinder with a glass plate and shake ; then
pour the contents of the cylinder into a filter. If the first por-
tion which filters, the filtrate, is not clear, pass it through the
filter a second time.

Repeat the experiment, using 2 cc. potassium sulfid solution,
2 cc. hydrochloric acid, and 10 cc. water in place of the dilute
cochineal solution.

Questions. ( i) What effect did the animal charcoal have upon
the color of the solution? (2) What property does this show
auimal charcoal to possess ? (3) What was the result of filter-
ing the potassium sulfid solution ? (4) What property does this
show animal charcoal to possess ?

56, Products of Combustion.— The carbon dioxid gas
given off from either a caudle or a gas flame can be col-
lected bj' arranging an apparatus like that shown in Fig.
25. A metal funnel is connected with a
delivery tube which passes into a solution
of lime water, Ca(0H)2, in a test-tube.
The carbon dioxid given off from the
flame passes into the lime water and by
forming calcium carbonate causes it to
become cloudy. Ca(OH), + CO^ =
CaCOj -|- H^O. The carbon comes from
the gas which undergoes combustion, and
is combined with hydrogen as hydrocar-
bons. That a candle produces its own
combustible gases can be proved by col-
lecting some of the gas with a glass ttibe Fig- 25.— collecting

. carbon dioxid from

and rubber bulb as shown in Fig. 26. caudie.

This gas can then be burned as indicated in Fig. 27. The

54

AGRICULTURAL CHEMISTRY

Fig. 26. — Obtaining unburned gas
from candle.

The car-
present iu
tissues are

hydrogen of a gas or candle forms H^O during combus-
tion, and can be collected by passing the products of

combustion through suitable
absorbents. If a dry test-tube
is held above the flame, a little
moisture will collect on the
sides of the test-tube.

57. Compounds of Carbon.
— Chemicall}', carbon forms a
very large number of com-
pounds, more, in fact, than
any other element
bon compounds
plant and animal
studied in a separate division
of chemistry known as organic chemistry, while those
compounds of carbon which are in com-
binati<?n with the mineral elements, as
calcium, sodium, and potassium, are
studied in inorganic chemistry. No well-
defined boundary line, however, can be
established between these two divisions
of chemistry.

58. Importance of Carbon. — The com-
pounds found in plant and animal bodies
contain carbon in larger amounts than
any other element ; consequently the
carbon compounds take a very import-
ant part in animal and plant growth.

Carbon is the element essential for the production of heat

Fig. 27. — Combus-
tion of gas from
candle.

CARBON 55

when fuels and foods are oxidized. Commercially, the
compounds of carbon are of great importance as they
are found in foods, fuels, and in all animal and plant
products.

Carbon is found in the air in the form of carbon dioxid
in sufficient amounts for the production of crops. It is
also found in large amounts in human and animal foods;
but because of its abundant presence, and its distribution
in balanced form, it has not been considered to take such
an important part economically in the production of plants
as the element nitrogen. It is, however, equally impor-
tant, although its natural distribution is such that it does
not require as much effort, on the part of man, to obtain
it as other forms of food materials. Nevertheless, the
carbon compounds, particularly in food materials, should
not be disregarded or considered of little or no importance
because of their abundance. In the study of foods and
the study of soils and fertilizers, some of the compounds
of carbon are considered more in detail.

CHAPTER VIII
Water
59. Chemical Composition. — That water is composed
of hydrogen and oxygen in approximately the proportion
of 2 volumes of H to i of O can be demonstrated bypass-
ing a current of electricity through water and collecting
the escaping gases. Oxj'gen will be
liberated at the positive electrode,
while hydrogen will be liberated at the
negative electrode. That water is
composed of i6 parts, by weight, of
oxygen, to 2 parts, by weight, of
hydrogen, can be demonstrated by
passing hydrogen gas over copper
oxid heated in a tube. The reaction
which takes place is CuO + 2H :=
H.^0 + Cu. If suitable provisions are
made for weighing the oxid of copper
used, and the water produced, it will
be found that the weight of the
water bears a definite relation to the oxid of copper
reduced. For every loss of 16 grams of oxygen
from the copper oxid, 18 grams of water are produced,
showing that water is eight- ninths, by weight, oxygen.

Experiment 8. — Distillation of water. Connect flask A (Fig.
29) with the bent tube B to the condensing apparatus issued
for this experiment. Place the distilling flask upon the sand-
bath and in position as shown in Fig. 29. Fill the tank of the
distilling apparatus, and half fill the flask, with water. Apply

Fig. 28.— Electrolysis
of water.

WATER

57

iieat to the flask, and reject the first portion of water that is dis-
tilled. Distil about 25 or 30 cc. of water.

Tests, (i) Thoroughly clean out your porcelain evaporating
dish, if necessary using a little white sand for scouring, rinse
■svith distilled water, and
then by placing the evap-
orator upon a sand-bath,
evaporate some of the
distilled water to dry-
ness. Carefully regulate
the heat so that as the
water evaporates there
will be less and less heat.
This is to prevent the
breaking of the evapo-
rating dish by too much
heat at the close. Ex-
amine the evaporating
dish. See if there is
any residue. (2) Evapo- Fig. 29.— Distillation of water,

rate to dryness a similar amount of ordinary water, and observe
the residue.

Questions, (i) Why do the contents of flask A. become cloudy
after boiling and cooling ? (2) Why was the residue obtained by
one test and not by the other ? (3) What became of the residue
when the water was distilled? (4) How could you distil water
on a larger scale for drinking purposes, if necessary to do so?

60. Physical Properties. — When water cools, it
reaches its maximum density at 4° C ; below this point,
it expands, and hence ice has a lower specific gravity
than water. All natural waters contain more or less im-
purities in the form of mineral and vegetable matter and
gases. Pure water can be prepared only by distillation.
When a substance, as salt, is dissolved in water, a solu-

58 AGRICULTURAL CHKMISTRY

tion is obtained. The particles of the material are sepa-
rated in the process of solution, and every part of the so-
lution, even though dilute, contains some of the dissolved
substance. When a substance is dissolved, ions are pro-
duced. They are small masses of the material that have
undergone changes due to the action of the solvent. The
ions possess definite electrical properties. When a sub-
stance goes- into solution, the process is both physical and
chemical. In some cases a change of temperature occurs,
as when ammonium nitrate solution is made.

i6. Water of Crystallization. — Many substances con-
tain, in chemical combination, water necessary for the
formation of crystals. This is what is meant by water
of crystallization. Without this water, crystals could
not be formed. The amount of water required bears a
definite relation to the composition of the crystals. When
copper sulfate crystallizes, 7 molecules of water of crys-
tallization are added to the substance. In purchasing
some substances, as sulfate of soda, a large amount of
water is obtained, as this compound contains 10 molecules
of water of crystallization. When the substance is heated
in an oven, to a sufiiciently high temperature, usually
above 100° C, the water of crystallization is expelled and
the anhydrous substance is obtained. Water of crystal-
lization is entirely different from hydroscopic moisture or
moisture which is absorbed from the air. Some chem-
ical compounds, when exposed to the air, give up their
water of crystallization. Such substances are called
efflorescent. Other compounds, as KOH and CaCl^, ab-

WATER 59

sorb moisture from the air. Such substances are called
deliquescent. Water takes an important part in chem-
ical reactions ; in fact, many of the reactions expressed
in the form of equations could not take place without the
presence of water.

62. Natural Waters.— Rain, spring, lake, river, and
sea waters are some of the principal forms in which water
is found in nature. Some waters contain a sufficient
amount of dissolved salts to give them
definite characteristics. Such are
known as mineral waters. The most
common impurities in water are lime,
magnesia, potash, soda, and iron com-
pounds. These substances give prop-
erties to the water which cause them
to be characterized as hard or soft, Typhoid baciuus.
according to the nature and amount of minerals dis-
solved. All natural waters are liable to contamination,
and the organic impurities of water serve as food for dis-
ease-producing organisms. The sanitary condition of
the water supply has an important bearing upon health.
Typhoid fever, cholera, and other bacterial diseases are
frequently caused by poor drinking water. The spores
of the organisms present in the water are taken into the
body where they rapidly multiply. Surface wells, par-
ticularly when near barns and dwellings, and in thickly
settled regions, are frequently in an unsanitary condition.

63. Impurities in Water. — The nature of the impuri-
ties in the soil through which water flows determines the
kinds of impurities in the water. If a soil is polluted

6o AGRICUIvTURAL CHEMISTRY

with decaying animal and vegetable refuse matters, the
soluble parts of these materials along with the countless
organisms which they contain, become a part of the
drinking water. The impurities in well waters are (i)
organic matter, and (2) mineral salts. When waters are
charged with excessive amounts of organic matter, the
solids obtained by evaporating the water to dryness
blacken when ignited. The carbon compounds in a liter
of some water will require 20 mgs. or more of oxygen for
oxidation. The organic matter may decompose and be-
come harmless, but it is liable, in times of epidemics, to
furnish food for disease germs.

A water that is comparatively free from organic matter
is not nearly so apt to be a source of trouble by conveying
disease germs as one that contains a large amount of
organic refuse, as this is the best kind of food for the
development of germs which cause man}^ of the most fatal
diseases. Vegetable matter, as a rule, is not as harmful
in a water as is animal matter. The organic matter that is
dissolved in waters is constantly decaying ; this decom-
position is the result of the workings of minute organisms
known as bacteria, and the disease-producing bacteria may
be present as well as the harmless kinds. The history of
the water supply of large cities has shown that a water
which is comparatively free from organic matter is the
best for household purposes. The reasons are obvious.
Excessive amounts of nitrogenous organic matter in
drinking waters are particularly objectionable, as the
source of this material is often sewage or surface drain-
age, as from a swamp.

WATER

6l

Deep well waters are less liable to be contaminated with
organic impurities than surface wells, but a deep well is
not above suspicion because the layers of soil are subject
':o changes in slope, and the water from a deep well may

Fig. 31 — Well contaminated with drainage from swamp.

receive surface drainage from some distant place, as indi-
cated in the illustration (Fig. 31). Although the soil
would remove a portion of the impurities and the organic
matter would be partially oxidized, the water would not
be entirely free from contamination.

64. Location of Wells. — The well should be remote
from barns and cesspools. Large trees about wells are
objectionable because the water is fouled by waste matter
thrown off by the roots. The top of the well for 6 or 8
feet should be laid with cement. The well platform
should be tight so that small animals are kept out.
Drain water from the spout should be carried away from
the well platform and the watering trough should not be
directly over the well. The land should slope away from
the well and the surfacing should be of clay. The well
should have ventilation, and should occasionally receive
a cleaning.

65. Mineral Impurities.— Calcium carbonate, calcium

62

AGRICULTURAL CHEMISTRY

sulfate, sodium chlorid, and sodium sulfate are the most
common minerals present in water. In alkali waters the

Fig. 32.— Construction of well.

mineral impurities consist of large amounts of sodium or
potassium compounds, and there is no way of improving

WATER

63

such waters except by distillation. Different kinds of
mineral matter, if present in excessive amounts, may im-
part medicinal properties ; magnesium sulfate (Epsom
salts) acts as a purgative,
while calcium sulfate causes
costiveness. Strong alkaline
waters can generally be de-
tected by their salty tasje.

The presence of a large
amount of limestone in waters
is not so serious as the pres-
ence of other minerals. Waters
sometimes contain limestone
to such an extent that when
boiled they become cloudy,
which is because of the re-
moval of the carbonic acid Fig. ss.-Charcoal water filter.

gas ; this caused the limestone to remain in solution.

Waters that contain limestone are not generally consid-
ered injurious to health although they
are not so satisfactory for cleaning pur-
poses on account of the lime acting upon
the soap and forming a scum of insoluble
lime soap. A large amount of lime-
stone, gypsum, etc., is what causes waters
to be hard. Some waters contain iron
compounds, as carbonate of iron which,
upon contact with the air, forms hydrate

of iron, and is deposited as a brownish red sediment.

Some waters contain so much mineral matter that when

Fig- 34 — Unglazed
porcelain filter.

64

AGRICULTURAL CHEMISTRY

used for generating steam they produce a large amount of
boiler scale. This can be partially prevented by the use
of materials containing tannic acid.

66. Methods of Improving Drinking Waters. — (i)

By boiling, which destroys disease-producing organisms.

Boiled or sterilized water, however, is not free from the

poisonous compounds
which many organisms
produce. In cases of
pestilential diseases,
water should always be
boiled.

(2) By filtering
through charcoal or
through disks of un-
glazed porcelain-like
material, which results
in removing a large pait
of the organic matter.
Special care, however,
should be taken to keep
the filter clean, other-
wise it will be a source
of contamination. Boil-
— : ing the water before fil-

Fig. 35.-Pasteur water filter. tcriug alsO imprOVCS itS

sanitary condition. One of the most effectual forms of
water filters is the Pasteur filter, in which the water
passes through a series of tubes which present a large sur-
face area for filtering.

WATER 65

(3) By distilling, which removes all mineral impurities,
and the water is also purified from organic matter. It is
the most effectual way of removing all kinds of impurities
and rendering the water free from organisms, and safe for
use.

CHAPTER IX
Air

67. Air a flechanicai flixture. — Air is a mechanical
mixture composed of a number of gases and compounds
in about the following proportions : (i) nitrogen, 79 per
cent.; (2) oxygen, 20 per cent.; (3) carbon dioxid, 0.04
per cent.; (4) ammonium compounds in small amounts;
(5) moisture; (6) ozone; (7) hydrogen peroxid ; (8)
argon ; (9) dust : organic matter, and micro-organisms.
That air is a mechanical mixture is shown by its not hav-
ing a constant chemical composition, which is necessary
for all compounds, and when nitrogen and oxj'gen are
mixed, in the same proportion as in air, there is no evi-
dence of a chemical reaction, as change of volume or
temperature. The air that is dissolved in water is of
different composition from atmospheric air, due to the fact
that oxygen is more soluble in water than is nitrogen.
The occurrence of nitrogen and oxygen in the air, and
the chemical and physical properties of these gases have
been discussed in Chapters IV and V.

68. Carbon Dioxid. — The amount of carbon dioxid in
the air is small, about 0.04 per cent., and it is supposed
to remain fairly constant in amount. It is produced
from : (i) combustion of carbon-containing materials, as
fuels ; (2) decaying of organic matter ; and (3) respira-
tion of animals. The carbon dioxid of the air serves as
food for plants and is used for the construction of plant
tissue. The amount produced and that used by vegeta-

AIR 67

tion nearly balance each other, so that the carbon dioxid
in the air remains fairly constant. While the percentage
amount in the air i3 small, the total amount is quite
large ; it is estimated that over each acre of the earth's
surface, there are about 30 tons of carbon dioxid at the
disposal of plant bodies. Carbon dioxid itself is not
such a poisonous gas, but it is usually associated in

Fig. 36. — Ventilating board in window for obtaining fresh air.

respired air with noxious and poisonous products thrown
off by the lungs. Hence the amount in a room is taken
as the index of the completeness of ventilation. When-
ever the carbon dioxid in a room exceeds o.i per
cent., the poisonous products associated with it are

68 AGRICUI.TURAL CHEMISTRY

considered to be too large in amount for perfect sanitary
conditions. While carbon dioxid is a product of respira-
tion, and is of no direct economic importance to animals,
it is indirectly of great importance because of its serving
as food for plant bodies. It is a heavy gas, but in a room
it diffuses and is quite evenly distributed. Its presence
in pure and in respired air can be shown by the following
experiment :

Experiment g. — Pour lo cc. of lime water (calcium hydrate)
into a test-tube, and blow through it, using for the purpose a clean
glass tube. Observe the precipitate of calcium carbonate. Expose
about ID cc. of lime water in a beaker for twenty-four hours, and
observe the result. The reaction which takes place between the
lime water and the carbon dioxid of the aiir is as follows :
Ca(0H)2 + CO2 = CaCOs + H^O.

Questions, (i ) What caused the precipitate to form? (2) What
was produced? (3) Is CaCOs soluble in water? (4) How do you
determine whether or not a gas is CO2? (5) How does the product
from this experiment compare with that from the burning candle?

In the ventilation of dwellings, barns and stables, it is necessary
that the products of respiration be removed as completely as possi-
ble and not allowed to accumulate and endanger health. Pure air
is as important as pure food or water. Impure air is frequently the
cause of disease and indirectly it may, by lowering the vitality of
the individual, prepare the way for disease. When gasoline or
kerosene is used as fuel, more thorough ventilation is necessary
than when wood or coal is used, because the products of combus-
tion from the gasoline and kerosene are given off into the room
instead of being carried out through the chimney. The subject of
ventilation, which forms a part of sanitary chemistry, is, as a rule,
given too little attention.

69. Ammonium Compounds — When nitrogenous or-
ganic compounds decay, ammonia gas, NH3, is given off.

AIR.

69

Since nitrogenous animal and vegetable matters are con-
stantly undergoing decay, some ammonia is always pres-
ent in the air. The ammonia gas unites with the carbon
dioxid and forms ammonium carbonate. In barns and
stables, where the ventilation
is poor, abnormal amounts of
carbon dioxid and ammonia
are formed from the respiration
and waste products of animals.
When carbon dioxid forms to
such an extent that it produces
a white coating upon stones
and boards, it shows enough
ammonium carbonate to be in-
jurious to animals. Nitrogen,
in traces, in the form of ammo-
nium nitrate and nitrite, is
also present in the air. The
amount of combined nitroge-
nous compounds in the air is
small and is not sufficient to
furnish food for plants.

70. rioisture. — The amount
of moisture in the air ranges

between widelimits, fromcom- ^^^^^eVforTemSg'fouiair!^'"'
plete saturation to desert conditions. When the air con-
tains all the moisture it can hold, it is said to be saturated.
Under ordinary conditions, the humidity, or per cent, of
saturation ranges between 60 and 85. The amount of
moisture in the air has an influence upon plant growth,

70 AGRICULTURAL CHEMISTRY

rather because it modifies the conditions of the at-
mosphere than because it furnishes moisture directly for
plant growth. The humidity of the air also influences
many farm operations, as the curing of cheese, which is
best effected ' in an atmosphere containing about 85 per
cent, of moisture.

71. Ozone and Hydrogen Peroxid. — ^These are oxidi-
zing agents, present in the air only in traces. Ozone is
a modified or allotropic form of oxygen. It is more
active than ordinary oxygen. Hydrogen peroxid (H2O2)
readily gives up one of its atoms of oxygen for oxidation
purposes. H^Oj = H^O + O.

72. Argon and Helium are elements which are present
in the air in small amounts. Argon makes up about i
per cent, of the volume of the air, and is like nitro-
gen in many of its chemical characteristics, but is even
more inactive and inert than nitrogen ; it is the most in-
active element known. Argon is not supposed to take
any direct part in animal or plant life.

73. Organic Impurities.— The amount of dust, dirt,
and impurities in the air varies with the conditions, as
rainfall, local influences, and sources of contamination.
Fine particles of dust, containing decaying vegetable mat-
ter, are carried long distances by the wind. This decay-
ing vegetable matter often contains spores of disease
germs. The dust and impurities in the air can be ob-
served when a beam of sunlight finds its way into a room;
then the particles of dust will be seen floating in the air.
When the air in a room is not in motion, the dust parti-

AIR 71

cles separate and settle very much as fine clay separates
from water which is not disturbed. There are many
different kinds of organic impurities present in the air.
The most objectionable of these are decayed refuse mat-
ters, particularly of animal origin. The air which passes
over swampy, undrained land, is contaminated with im-
purities.

74. Air as a Source of Food. — In both animal and
plant life, air plays an important role. It contains oxy-
gen necessary for the existence of animals and carbon
dioxid essential as food for plants. Over 90 per cent, of
the total food of our agricultural and useful plants is ob-
tained from the air as carbon dioxid, or from rain which
finds its way into the soil. Food which is oxidized in
the body requires oxygen for combustion. Hence it will
be seen that the air is the source of the larger portion of
the total food of both plants and animals.

CHAPTER X
Acids, Bases, Salts, and Neutralization

75. Classification of Elements. — Elements are divided
into two classes: (i) Acid-forming elements and (2)
base-forming elements. This -division is made according
to the properties of the elements.

The basic elements are commonly called metals : iron,
copper, silver, and lead are examples. The basic elements
form, with H and O, bases or hydroxids, as KOH and
NaOH. A base is a compound composed of a metal in
combination with OH, the hydroxyl radical. This radical
can be replaced by an acid-forming element.

An acid is a compound containing hydrogen which
can be replaced by a metal. In the preparation of hydro-
gen, the H of HCl was replaced with zinc. The acid- form-
ing elements, with hydrogen, and with H and O, form
acids.

Bases and acids are opposite in character and proper-
ties. Acids color blue litmus red, bases color red litmus
blue. For purposes of study, the different acid- and base-
forming elements are subdivided into families and groups
which have definite relationships and common character-
istics.

76. Salts. — When an acid and a base are brought to-
gether, a chemical reaction takes place known as neu-
tralization. The product formed by the reaction is a
salt. A salt is a compound formed by the union of acid-

ACIDS, BASES, SALTS, AND NEUTRALIZATION 73

and base-forming elements. Salts are neutral compounds.
In the study of acids, bases, and salts, the character of
the compound can always be determined from the formula
as Ca(0H)2. Calcium hydrate is a base because it Con-
tains the hydroxy 1 radical OH. CaCl^ is a salt because
it is composed of the acid- forming element CI and the
base-forming element Ca. HCl is an acid because it is
composed of hydrogen and the acid-forming element CI
and the H can be replaced by a metal. Acids and bases
do not exist as such to any appreciable extent in nature.
Salts are neutral compounds and the materials most ex-
tensively found. In the table, Section 15, the character-
istic properties of some of the elements as acid- or base-
forming, are given. A few elements, as will be discussed
later, have both acid and basic characteristics.

77. Radicals — A radical is a group of elements which
enters into chemical combination like a single element.
When three elements combine to form a compound the
combination is made in the following way : Two of the
elements first form a radical, and then this radical com-
bines with the third element. Every radical has its own
valence which is independent of that of its separate atoms.
A radical can exist only in chemical combination ; it can-
not be separated. Its individuality as a radical exists
only when in combination. The elements which unite
to form a radical do not do so according to the law of
valence. There are only a few of the more common
radicals which require special study at this stage of the
work. Example : When H, S, andO combine, the S and
O first form a radical, SO^, which has a valence of 2. Two

74 AGRICULTURAI, CHEMISTRY

atoms of H combine with one SO^ radical and form HjSO^.
Some of the more common radicals are :

Radi-
cal.

CO3

CIO3

NO3

Valence.
2

I
I

Compounds formed
with H.

Carbonic acid

Chloric acid

Nitric acid

Compounds formed
with metals.

Carbonates

Chlorates

Nitrates

NH,

3
I

I
2
I
2
2

Phosphoric acid

Phosphates

Ammonium compounds

Hydroxids

Silicates

Nitrites

Sulfites

Sulfates

OH

SiOs

NO2

SO3

SO4

Water
Silicic acid
Nitrous acid
Sulfurous acid
Sulfuric acid

78. Naming of Acids. — Acids are named according to
the characteristic acid element or radical present, as sul-
furic acid, H2SO4, in which S is the characteristic acid
element. The most common acids have the ending ic.
Some acids have an ous ending, as H.^S03, sulfurous
acid. The acid which has the smaller amount of oxygen
has the ending ous, while the acid which has the larger
amount of oxygen has the ending ic.

Name the following acids : HNO3, HNO^, H,SO„
H,S03, H3PO,, H3PO3, H3ASO,, H3ASO3.

79. Naming of Bases. — Bases are named according to
the characteristic base element which they contain. All
bases are called hydroxids, as calcium hydroxid, Ca(0H)2,
and potassium hydroxid, KOH.

The rule in regard to the endings ic and ous applies in
the case of bases as well as in that of acids; that is, when
an element forms two hydroxids, the ending ic is applied

ACIDS, BASES, SALTS, AND NEUTRALIZATION 75

to the one with the larger amount of hydroxyl, and the
ending ous to the one with the smaller amount.

Name the following bases: Mg(OH),, NH.OH, NaOH,
Fe(OH)„ Fe(0H)3, A1(0H)3, CuOH, Cu(OH),.

80. Naming of Salts. — Salts are named according to
the acid and base elements which they contain, as K.^SO^,
potassium sulfate, composed of potassium, K, and the
sulfate radical, SO^. Most salts have an ending ate.
A few have an ending ite. The salts derived from the
acids with the ic ending always have the ate ending, as
sulfuric acid, which always produces sulfates, phos-
phoric acid, phosphates, and nitric acid, nitrates. The
acids ending with ous produce salts which end in
ite, as nitrous acid always produces nitrites, and sul-
furous acid, sulfites. Salts that are composed of only
two elements always have an ending of id, as .sodium
chlorid, NaCl, and sodium sulfid, Na^S.

81. Double Salts. — A double salt is one that is com-
posed of two base elements in combination with one acid
radical, as NaKSO^, sodium potassium sulfate. Double
salts are formed from acids which contain two replaceable
hydrogen atoms, as H^SO^, by replacing one of the H
atoms with one base element and the remaining H atom
with another base element. This is represented graphi-
cally as follows :

H\ Na.

h/ ' K

H,SO, = >S0, = >SOi-

82. Acid Salts. — An acid salt is one in which only a
part of the H of the acid has been replaced. An acid

76 AGRICULTURAL CHEMISTRY ' ■

salt always contains H, a metal, and a radical. HNaSO^
is acid sodium sulfate, as only one H atom has been
replaced with Na. A normal salt contains no replace-
able H.

83. Basicity of Acids. — Acids with one replaceable H
atom are called monobasic acids, as HCl and HNO3.
Acids with two H atoms are dibasic, as HjSO^, H^SiOg,
and H2CO3. When an acid contains three replaceable H
atoms, it is tribasic, as H3PO4.

84. Two Series of Salts. — When a base element has
more than one valence, it forms two series of salts. For
example, Fe has a valence of 2 and 3. The first series
of salts is known by the ending ous. The second series
has an ic ending. The one ending means that the com-
pound is formed from the lower valence of the element,
as FeClj, ferrous chlorid, while FeCl3 is called ferric
chlorid. There are two series of copper salts ; CuCl is
called cuprous chlorid, and CuCl^, cupric chlorid.

Name the following salts : FeClj, FeClj, FeSO^,
Fe,(S0,)3, Fe(N03)„ Fe(N03)3, Fe(OH)„ Fe(0H)3,
HgCl, HgCl,, SnCl^, SnCl,, MnCl,, MnCl,.

Experiment 10. — Neutralization and preparation of salts.
Obtain two burettes from the instructor for these experiments.
Measure out 5 cc. of concentrated HCl and 95 cc. of water ;
after mixing, fill one of the burettes with this diluted HCl (Fig.
38). Use your funnel for filling the burette, and then carefully
wash the funnel. Prepare a dilute solution of NH4OH, using 90
cc. of water and 10 cc. of the shelf NH4OH. After mixing, fill the
second burette with this preparation of diluted NH^OH. Before
using the solution in the burette, it should be lowered to the zero-
point by carefully opening the pinch-cock. Always allow the tip

ACIDS, BASEJS, SAINTS, AND NEUTRAI^IZATION

77

from the burette exactly 20

of the burette to be filled with the solution before beginning the
experiment.

Into a small beaker, measure
cc. NH4OH, with 10 or 12 drops
of cochineal solution, which is
changed to a deep purplish color
by the alkali ; then slowly add HCl
from the other burette, constantly
stirring the solution in the beaker
until a decided change in color is
observed. When all of the NH^OH
has been neutralized, the solution
has a yellowish red color. Note the
number of cubic centimeters of
HCl used for neutralizing the 20 cc.
of NH^OH solution. Add a drop
or two from the NH^OH burette
and note if there is a change of
color. When the solution is neu-
tralized, one or two drops of HCl
or NH^OH should give a decided
change of color. If too much acid
has been used, add a measured
amount from the NH4OH burette
until the solution is neutralized.
Finally note the total quantity of
HCl and NH^OH used. Repeat this
experiment, using 20 cc. of the
HCl solution .

Questions. ( i ) What was formed
when the HCl neutralized the
NH^OH solution? (2) Write the
reaction. (3) What would be the
result if the neutralized solutions ^'^^ 38.-Burette.

were evaporated to dryness ? (4) Calculate the amount of HCl re-
quired to neutralize i cc. of NH4OH.

78 AGRICULTURAI. CHEMISTRY

Experiment ii. — Neutralization. Repeat Experiment lo, using
dilute HjSO^ and NaOH solutions that have been prepared for this
experiment. After completing the experiment, clean the burettes
thoroughly and return them to the instructor.

Questions, (i) What was formed when HjSO^ neutralized
NaOH? (2) Write the chemical reaction. (3) What was formed
as the products of this reaction? (4) How can the salt product be
obtained? (5) In writing the reaction, why do we vise 2NaOH in-
stead of NaOH? (6) How does the product of Experiment 10
differ from the product of Experiment it? (7) What other
acids could be used for neutralizing NaOH and NH4OH ? (8) What
other bases could be used for neutralizing HCl and HjSO^?
(9) What is an acid? (10) What is a base ? (11) What Is a salt?
(12) Which do we find most abundantly in nature, acids, bases, or
salts ? Why ?

Experiment 12. — Preparation of a salt. Put 10 cc. dilute
HCl and 10 cc. water into the evaporator. Measure out 10 cc. of
NaOH into a beaker and add 50 cc. water. Add this diluted NaOH
to the evaporator a little at a time until the solution is neutral to
litmus paper. Do not dip the paper into the solution, but transfer
a drop by means of a glass rod from the evap-
orator to the paper. In case too much NaOH
has been used, add a drop or two of the acid.
Bases or alkalies turn red litmus paper blue,
while acids turn blue litmus paper red. When
Fig. 39.-Sodium chlorid the solution is neutral, it has no perceptible
crystals (common salt), action upon litmus paper. Place the evap-
orating dish upon the sand-bath, and apply heat until the solution
is evaporated to dryness. Carefully regulate the flame so as to
avoid excessive heating. This will prevent spattering when the
solution becomes concentrated.

Questions. ( i ) What is left in the evaporator ? (2) From what
was it produced? (3) Write the chemical reaction. (4) Taste
some of the material in the evaporating dish. How is it possible for
this material to be formed from two such unlike compounds as HCl

ACIDS, BASES, SAINTS, AND NEUTRALIZATION 79

andNaOH? (5) What is neutralization ? (6j Are definite amounts
by weight of HCl and NaOH required for neutralization? (7) How
many molecules of HCl are required to neutralize one of NaOH?
(8) How much does a molecule of HCl weigh? (9) Of NaOH?
(10) How many parts by weight of each must be taken for neu-
tralization ? (11) How does this illustrate the law of definite pro-
portion ?

CHAPTER XI
Hydrochloric Acid, Chlorin, and Chlorids

85. Occurrence. — The element chlorin is never found
in a free state in nature, but is always in combination
with other elements, as with sodium, forming sodium
chlorid. With hydrogen, chlorin forms hydrochloric
acid.

86. Preparation. — Hydrochloric acid is produced by
the action of HjSO^ on NaCl, the reaction being
2 NaCl + H,SO, = Na^SO, + 2HCI. Heat is applied
and the hydrochloric acid gas is expelled and col-
lected in water. In the preparation of hydrochloric acid,
the CI part of the compound is supplied by the NaCl, while
the sulfuric acid furnishes the hydrogen. Hydrochloric
acid can also be made by direct union of the elements
hydrogen and chlorin. It is prepared in the laboratory
in the following way :

Experiment 13. — Preparation of hydrochloric acid. Arrange
the apparatus as shown in Fig. 40. A sand-bath, containing
sand, is placed upon either the tripod or the large ring of the iron
ring-stand. Tube B connects flask A with WoulfF bottle C, which
contains 100 cc. of water. The tube is made from a piece of glass
tubing 22 to 24 inches long, with one right-angled bend about 3
inches from the end, and another, parallel and about 6 inches from
the first bend. This tube is connected with both flask A and the
Woulff bottle by means of tight-fitting corks. Tube B passes into
the bottle but 7iot below the surface of the liquid. Through a tight-
fitting cork in the middle neck of Woulff bottle C passes a safety
tube so adjusted that it dips just below the surface of the water in
C. This safety-tube is a straight piece of glass tubing, 9 or 10

HYDROCHLORIC ACID, CHLORIN, AND CHLORIDS 8 1

inches long. Woulff bottle C is connected with a second Woulff
bottle by means of a bent tube which passes below the water in the
second bottle but is above
the water in the first bot-
tle. The apparatus, as
constructed, allows the
gas which is generated in
flask A to pass through
into C and saturate the
water. Some of the acid
passes over into the sec-
ond Woulif bottle. Since
the delivery tubes in C do
not pass below the surface
of the liquid, and the
pressure is equalized, no
liquid can be drawn back
into flask A.

Place 15 grams sodium
chlorid (NaCl, common
salt) and 30 cc. of concen-
trated H2SO4 in flask A.
Apply heat to the flask,
and after ten minutes re-
move the burner and test Fig- 40— Preparation of hydrochloric acid,
the liquid in both Woulff bottles with litmus paper. Then make
the following tests :

( I ) Disconnect the delivery tube and test the escaping gas with
wet litmus paper. (2) Collect a little of the gas in a test-tube, and
test it with a burning splinter. (3) Put 2 or 3 cc. of silver nitrate
(AgNOa) into a test-tube and then a like amount of HCl from the
first Woulff bottle. Observe the result. (4) Leave the test-tube and
contents exposed to strong sunlight for a few minutes. (5) Put a
small piece of zinc into a test-tube and cover it with some of the
acid from the first Woulff bottle. Observe the result.

Questions. ( r ) What chemical reaction took place when HjSO^

82 AGRICULTURAL CHEMISTRY

and NaCl were brought together? (2) Is HCl a solid, liquid, or
gas? Why? (3) Color? (4) Is it soluble in water ? Why? (5)
What was formed when the HCl was added to the test-tube con-
taining AgNOj ? Give the reaction. (6) Is HCl combustible or a
supporter of combustion? (7) What is a chlorid ? (8) What
effect would HCl gas have upon plants ?

87. Properties. — Hydrochloric acid is a colorless gas,
soluble in water. When exposed to the air, it combines
with the moisture of the air. The concentrated acid
used in the laboratory is a solution of about 40 per cent.
HCl. Chemically, HCl is an active acid, and is neither
combustible nor a supporter of combustion. When it
neutralizes bases, chlorids are always formed. Hydro-
chloric acid is distinguished from other acids by its reac-
tion with silver nitrate, a white precipitate of silver
chlorid being produced which is soluble in ammonia and
is blackened in sunlight. Hydrochloric acid is used
extensively in the laboratory in the preparation of vari-
ous compounds, and for the production of chlorin.

88. Preparation of Clilorin. — Chlorin is prepared by
the action of an oxidizing agent, as manganese dioxid,
upon hydrochloric acid, manganese chlorid, water, and
chlorin gas being formed as products. The reaction is
MnO^ + 4HCI = MnCl^ + 2H,0 + 2CI. In this reaction
the valence of manganese is changed from 4 to 2, and as
a result free chlorin gas is liberated. The method of
preparation in the laboratory is as follows :

Experiment 14. — Preparation of chlorin. It is preferable
to set up the apparatus for generating chlorin under one of the
hoods. Arrange the apparatus as shown in Fig. 41. Place 10
grams of MnOj and 15 or 20 cc. of HCl in flask A. By means of

HYDROCHLORIC ACID, CHLORIN, AND CHLORIDS 83

the delivery tube B, and a tight-fitting cork, the CI gas, when

generated, passes into the large cylinder, in which has been placed

a green leaf, a piece of colored cloth, and paper upon which is

some writing. The delivery tube passes through the hole in the

ground-glass plate, without any cork. To generate the chlorin

apply gentle heat to the flask, and

as soon as the cylinder is nearly

filled with the CI gas, which can be

observed by its color, remove the

flame so as to prevent any of the

gas from escaping into the room.

Do not inhale any of the fumes, as

they are irritating to the throat and

lungs. Make the following tests :

( I ) Observe the effect which the
chlorin gas has upon the cloth,
paper, and leaf. (2) To the cylin-
der, add 5 cc. water containing two
or three drops of indigo solution.
Observe the result.

Questions. ( i ) Give the physical
properties of CI gas, odor, weight,
and color. (2) What caused the
liberation of the CI gas from the
HCl? (3) Write the reaction. (4)
What are some of the chemical
properties of chlorin as observed F»&- 4i-— Preparation of chlorin.
from the changes which have taken place in the materials in the
cylinder? (5) What is a chlorid ? (6) Name five compounds con-
taining chlorin. (7) Why is CI gas employed as a disinfectant?
Explain its action as a disinfectant. (8) What is bleaching-powder,
and how is it used as a disinfectant? (9) NaCl is necessary for
animal life ; CI is one of the elements of the compound ; CI is de-
structive to animal life ; why can you not conclude that NaCl con
taining CI is destructive to animal life ?

84 AGRICUIvTURAI, CHEMISTRY

89. Properties. — Physically considered, chlorin is a
heavy, greenish yellow gas, with a penetrating, suffo-
cating odor. Chlorin gas is poisonous. Chemically, it
is an active element and has strong affinity for nearly all
other elements. It readily combines with metals, form-
ing chlorids, and light and heat are evolved during the
reaction. Chlorin is an active bleaching reagent, as it
changes the composition of vegetable dyes, thus destroy-
ing their color. Bleaching-powder is a mixture of cal-
cium hypochlorite and calcium chlorid, and when used
chlorin is liberated, Chlorin is also used as a disinfectant
and as a germicide, for it is destructive to life, particu-
larly to the lower forms. It is used extensively for both
bleaching and disinfecting purposes. Chlorin takes no
part directly in life processes, although its compounds,
particularly sodium chlorid, are necessary as mineral food
for animals.

90. The Chlorin Group of Elements. — Fluorin, chlo-
rin, bromin, and iodin form a natural group of elements,
known as the chlorin family. These elements are all
closely related. They form similar acids with H, and
similar salts with the metals. Some of the most im-
portant relationships and points of difference between
members of the chlorin family will be observed from the
following table :

Physical
Element. At. wt. conditions. H compound. Na compound.

Fluorin 19 Light gas HFl NaFl

Chlorin 35.45 Heavy gas HCl NaCl

Bromin 79-95 Liquid HBr NaBr

Iodin 126.85 Solid HI Nal

HYDROCHLORIC ACID, CHLORIN, AND CHLORIDS 85

91. Chlorids. — Combined with the metals, chlorin forms
chlorids. As a class, the chlorids are quite stable com-
pounds, inasmuch as chlorin has strong affinity for nearly-
all of the metals. The properties of the different chlorids
vary with the metal with which the chlorin is combined.
The chlorids do not take such a direct part in plant as in
animal nutrition. When present in either soil or water
in any appreciable amount, the soil is sterile and the
water is not suitable for either drinking or irrigation
purposes. Sodium chlorid is found in nature most
abundantly of any of the chlorids.

Problein i. — How much H.,S04 is required to combine with 2000
pounds NaCl in making HCl ?

Problem 2. — How much HCl can be made from 2000 pounds of
NaCl?

Problems. — How much Na^SO^ is produced when 2000 pounds
NaCl are used for making HCl ?

CHAPTER XII
Nitric Acid and Nitrogen Compounds

92. Occurrence. — Nitric acid does not occur in nature
in a free state, but nitrates or salts of nitric acid are found
as natural products. Since all normal nitrates are soluble
in water, the}' are never found in great abundance in
soils. In regions of scant rainfall, where climatic con-
ditions have been favorable for the formation of nitrates,
deposits of nitrate of soda are occasionally found. The
nitrifying organisms of the soil, when supplied with
food, moisture, suitable temperature, and other requisite
conditions, produce nitrates which are utilized as food
by plants. The process of nitrification which takes place
in the soil, results in changing the inert and unavailable
nitrogen to a soluble and available condition,

93. Preparation. — The same principle is applied in the
preparation of nitric acid as in the preparation of hydro-
chloric acid. It is produced by the action of H^SO^ upon
a salt ; when a chlorid is used, hydrochloric acid is the
product, and when a nitrate is used nitric acid is the
product. The reaction when sodium nitrate is used is :
2NaN03 + H,SO, = Na,SO, + 2HNO3.

Experiment 15. — Preparation of nitric acid. Special care
shonld be exercised by the student in the preparation of nitric acid,
because if any is spilled on the hands it causes painful burns and
wounds that are difficult to heal. Provided the student is careful
and follows the directions given, there is no danger whatever in
the preparation of this material. Arrange the apparatus as shown
in Fig. 42. The delivery tube used in the preparation of NHj may

NITRIC ACID AND NITROGEN COMPOUNDS

87

be used for this experiment. If necessary, a brick or block may
be placed under the cylinder. The delivery tube should pass into
and nearly to the bottom of a test-tube which is immersed in cold
water in the cylinder. Put 15 cc. concen-
trated sulfuric acid (H^SO^) and 10
grams of either sodium nitrate (NaNOj)
or potassium nitrate (KNO3) into the
flask and apply heat until about 4 or 5 cc.
of HNO3 is distilled and collected in the
test-tube. Do not remove the flame un-
less the end of the delivery tube is above
the liquid in the test-tube, otherwise the
liquid will be drawn back into the flask.

Make the following tests with HNO3.
(i) Remove a drop of the acid by means
of a glass tube, and apply it to either a
piece of woolen cloth or silk. Observe
the result. ( 2 ) Place a few" drops of indigo
solution in a test-tube containing 5 cc. of
water, then add about 2 cc. of HNO3. Ob-
serve the result. (3) Place a small piece
of copper in the test-tube containing the
remainder of the acid. Observe the result.
If no reaction takes place, add a little
water. Do not pour the contents of the
flask into the sink or waste jars until
cool, otherwise the hot acid coming in contact with cold water
may cause spattering of the acid.

Questions. ( i ) Why was H2SO4 used in the preparation of this
compound? (2) What material supplied the NO3 radical? (3)
Write the reaction which took place in the flask after heat was ap-
plied. (4) Is HNO3 a solid, liquid, or gas? Why ? (5) What caused
the red fumes to be given ofE when the copper was added to the
test-tube? (6) Does HNO3 give off H when a metal is added to it?
Why? (7) Why did the HNO3 bleach the indigo solution? (8)
Why is ordinary HNO3 colored yellow? (9) Is HNO3 ^^ active or
inert chemical ? (10) What is a nitrate?

Fig. 42. — Preparation of
nitric acid.

88 AGRICULTURAL CHEMISTRY

94. Properties. — When pure, nitric acid is a colorless
liquid; the commercial acid has a yellow color because
of the presence of oxids of nitrogen. Nitric acid is an
active oxidizing reagent, and when metals, as copper and
iron, are dissolved in it, brown fumes of NO2 are given
off because the hydrogen, as soon as liberated, is oxidized
by the excess of acid and NO2 is formed. H + HNO3 =
HjO + NOj. Nitric acid imparts a permanent yellow
color to wool, silk, and all albuminous matter.

95. Importance. — In the laboratory, nitric acid is used
as an oxidizing agent. It is used commercially in the
dyeing of cloth, although it has a tendency to weaken the
wool fibers. Salts of nitric acid are important because
they are of so much value as plant food, and particularly
in the manufacture of commercial fertilizer, where it sup-
plies nitrogen. Potassium nitrate is used in the manu-
facture of gunpowder. Nitrates are of great importance
in agriculture.

Ammonia

96. Occurrence. — Ammonium compounds are present
in small amounts in the air, rain water, and in the soil,
and are produced from decaying nitrogenous organic
matter. The chief source of the ammonia which serves
as the basis for the preparation of ammonium salts is
the ammonia water obtained in the process of purifying
illuminating gas made from soft coal. The nitrogen
compounds of the coal form ammonia gas, NH3, during
the destructive distillation process.

97. Preparation. — In the laboratory, ammonia is usu

AMMONIA 89

ally prepared from ammonium chlorid by treatment with
a strong base, as Ca(0H)2. The reaction is :

2NH,C1 + Ca(OH), = CaCl, + 2NH,0H.

Experiment 16. — Preparation of ammonia. Arrange appa-
ratus as directed for the preparation of HCl (see Fig. 40). Into
flask A, place 10 grams each of dry ammonium chlorid, NH4CI, and
powdered calcium hydroxid, Ca(0H)2, and 25 cc. water. Barium
hydroxid, Ba(0H)2, may be used in place of the Ca(OH).2. When
properly connected, apply heat to the sand-bath from eight to
twelve minutes.

Tests for Ammonia, (i) Test the gas with wet litmus paper.
Note the result. (2) Test the water in both Woulff bottles with
litmus paper, and note the result. (3) In an evaporator place 5 cc.
HCl and 10 cc. water. Disconnect the delivery tube from Woulff
bottle C, and pass some of the fumes of the escaping gas over the
acid in the evaporator. Avoid inhaling any of the gas. (4) Col-
lect some of the gas in a test-tube and then place the test-tube in-
verted in a cylinder about one-third full of water. (5) Adds cc.
of the NHj solution from either of the Woulff bottles to 5 cc. of a
solution of alum. Note the result.

Questions, (i) What material supplied the NH^ part of the
NH^OH ? (2) What caused the gas to be liberated from these ma-
terials? (3) What chemical reaction took place in flask A after
the heat was applied ? (4) Why was water used in the Woulff
bottle? (5) What did the water and the NH3 gas form? (6)
What reaction did the NH3 gas and the NH^OH give with the lit-
mus paper ? (7) Why was not this gas given off into the room?

(8) Why was not NH3 collected over water, like H, N, and O?

(9) What caused the water to rise in the test-tube? (10) Why
have you reason to believe that the NH^OH caused a chemical re-
action when added to the solution of alum ?

98. Properties. — Ammonia is a colorless non-combus-
tible pungent gas, which unites with water to form am-
monium hydroxid, NH^OH, a basic compound. It is

90 AGRICULTURAL CHEMISTRY

completely soluble in water, from which it is easily liber-
ated b)' heat. The gas can be reduced to liquid form by
cold and pressure. Liquefied ammonia passes back to the
gaseous condition wdth removal of the pressure, and in so
doing, heat is absorbed from surrounding bodies. If this
heat is absorbed from water, the temperature of the water
is lowered sufficiently to produce ice. This property of
liquefied ammonia is taken advantage of for the artificial
production of ice, and for refrigerating purposes. The
transportation of perishable food materials has been ren-
dered possible by this method of refrigeration,

99. Uses. — In the laboratory, ammonium hydroxid is
used extensively as a reagent for neutralizing acid solu-
tions and precipitating insoluble hydroxids. Ammo-
nium salts, w^hen present in any appreciable amounts, are
destructive to plants, (NHJ^SO^ being less injurious than
either NH.Cl or (NHJ^COg. Hence (NHJ.SO, can be
used in limited amounts as a fertilizer. Because of its
being a volatile alkali, ammonia is valuable as a reagent
for softening water.

In small amounts, so as to form very dilute solutions,
the ammonium compounds serve as food for plants, sup-
plying them with nitrogen which is used for producing,
within the plant cells, complex nitrogenous compounds,
as proteids. Ammonium compounds supply only one
form of nitrogenous plant food.

100. Oxids of Nitrogen. — Nitrogen forms five com-
pounds with oxygen :

NjO nitrogen monoxid or nitrous oxid.

NjO^ nitrogen dioxid or nitric oxid.

AMMONIA 91

N2O3 nitrogen trioxid or nitrous anhydrid.

N20^ nitrogen tetroxid.

N2O5 nitrogen pentoxid or nitric anhydrid.

While the oxids of nitrogen do not serve as either plant
or animal food, they are nevertheless important, and a
study of these compounds is necessary in order to under-
stand the subject of nitrogen.

loi. Anhydrids. — An anhydrid is an oxid of an acid
element, or the product which is left after the elements
which form water are abstracted from an acid. SO3 is
sulfuric anhydrid, and is the product formed by ab-
stracting H.,0 from H,SO,. H,SO, = H^O + SO3. 'N,0,
is nitric anhydrid, derived from two molecules of-HNOj.
2HNO3 == H^O + N2O5.

Derive and name the anhydrids of the following acids:
2H3PO,, H2CO3, H^SiOj, 2HNO2, H2SO3.

102. Law of riultiple Proportion. — When nitrogen
and oxygen combine, the number of parts of nitrogen in
the various compounds is constant, namely : 2, or 28
parts by weight in each compound. The number of
parts of O is always a multiple of the first combination,
N2O ; that is, it is either 2, 3, 4, or 5 times as much in
the other compounds as in the first one. This is an ex-
ample of the law of multiple proportion. When two
elements combine in more than one way, the amount by
weight of one of the elements remains constant in all the
combinations, while the amount of the other element is
always a multiple of the first combination.

The law of definite proportion holds true for each in-
dividual compound, while the law of multiple proportion

92 AGRICULTURAL CHEMISTRY

applies to the entire series, and is a broader application
of the law of definite proportion.

103. Importance of the Nitrogen Compounds. — The

compounds of nitrogen, particularly nitrates and ammo-
nium compounds, are of importance in agriculture as they
serve as food for plants. They are difficult to retain in
soils because of their solubility and the volatility of
ammonia. In human and animal foods, the nitrogenous
compounds are of importance in many ways ; hence, in
economic agriculture the compounds of nitrogen receive
special consideration.

Problefn i. — How many pounds of HNO3 can be produced from
100 pounds NaNOs?

Problem 2. — How much HjSOi is required when 100 pounds
HNO3 are made ?

Problem J.— Ho-w much NH^OH can be produced from 10 pounds
of NH.Cl?
.- Problem ^.— What per cent, of NH^OH is NH3?

CHAPTER XIII
Phosphorus and Its Compounds

104. Occurrence. — Phosphorus is found in nature in
combination with oxygen and other elements, forming
phosphates, as CagCPOJa. It is never found in a free or un-
combined condition. In soils, it is found in small amounts,
and in many rocks and minerals, as apatite or phosphate
rock, it is present in large amounts ; it is also found in the
ash of plants, and in animal bodies, particularly as a con-
stituent of bones.

105. Preparation. — It is prepared from bones, which
are first freed from organic matter by burning. The
bone ash is treated with sulfuric acid, producing acid
phosphates, which, when roasted with charcoal, liberate
free phosphorus.

106. Properties. — There are two forms of phosphorus:
the yellow and the red. Yellow phosphorus is a solid
which ignites at a low temperature. Red phosphorus is
an allotropic form of the element produced by heating the
yellow variety in a sealed tube. Yellow phosphorus
more readily combines with oxygen than does the red,
and is kept under water to prevent contact with air,

107. Oxids of Phosphorus. — When phosphorus is
burned in a current of oxygen or dry air, phosphorus
pentoxid, PjOg, is obtained. This material is a white
flocculent mass -which readily dissolves in water, forming
metaphosphoric acid. When phosphorus is burned in a

94 AGRICULTURAIv CHEMISTRY

limited amount of air, it forms phosphorus trioxid, P2O3,
which after long standing dissolves in water, forming
phosphorous acid. In fertilizer, soil, and food analysis,
the amount of phosphorus is expressed in terms of P2O5.

108. Phosphoric Acid and Phosphates. — Ordinary
phosphoric acid is produced by the action of H^SO^ upon
bone ash.

3H2SO, + Ca,iFO,), = 2H3PO, + 3CaS0,.

Salts of ortho or ordinary phosphoric acid are the most
common forms of the acid derivatives. Since this acid
contains three replaceable H atoms, three salts are formed,
as : NajPO^, normal sodium phosphate ; Na^HPO^, di-
sodium phosphate ; and NaH^PO^, monosodium phos-
phate. The three calcium salts of phosphoric acid are :

CaH^(P0j2, monocalcium phosphate.

Ca^HjCPOJa, dicalcium phosphate.

CagCPOJa, tricalcium phosphate.

In addition to the ordinary phosphoric acid, there are
other derivatives, as :

H3PO, = H20 + HP03 (metaphosphoric acid).

2H3PO, = H,,0 + H,P,0, (pyrophosphoric acid).

109. Phosphate Fertilizers. — In deposits of phosphate
rock, the phosphoric acid is mainly in combination with
calcium as Ca3(PO^)2, and is of little value as plant
food until it is treated with H^SO^ and converted into
monocalcium phosphate, which is soluble and available
as plant food. Ca3(PO,)2 + 2H2SO, = CaH,(PO,), +
2CaSO^. Large amounts of phosphates undergo this
treatment in the manufacture of commercial fertilizers.

PHOSPHORUS AND ITS COMPOUNDS 95

Experiment ij. — In a beaker on a sand-bath, dissolve V2 gram
of bone-ash in 10 cc. dil. HNO3 + 20 cc. H._,0 ; filter, and to the fil-
trate, while still warm, add 5 cc. ammonium molybdate, and then
stir. Observe the precipitate, which is a compound of phosphoric
acid, ammonium, and molybdenum.

Questions, (i) What was the solvent of the phosphoric acid?
(2) Why was the solution boiled and filtered ? (3) Describe the
color and properties of the precipitate.

Experiment 18. — Dissolve V2 gram of sodium phosphate in
10 cc. distilled water, then add 10 cc. of a solution containing V2
gram CaClj. Observe the result. Write the reaction. Repeat this
experiment, using AICI3 or alum in place of CaClj.

iio. Compounds of Phosphorus. — Phosphorus forms
a large number of compounds, as phosphates, metaphos-
phates, and pyrophosphates. It also combines with H,
CI, and I. With H it forms PH3, phosphine, an analo-
gous compound of NH3. Phosphorus also enters into
combination with C, H, N, O, and S, forming complex
organic compounds, as nucleated proteids and lecithin.
It is an element which has a wide range of combinations.

HI. Importance of Phosphorus and Its Compounds.

— The compounds of phosphorus, particularly the phos-
phates, are important in plant development, being essen-
tial forms of mineral food required for crop growth.
Agriculturally considered, phosphorus is one of the most
important of the elements. It is stored up in the seeds of
grains, and in combination with the elements which form
the organic compounds of plants, it takes an important
part in animal nutrition. Compounds of phosphorus are
used in the manufacture of matches, and as poison for in-
sects. Phosphorus forms a large number of compounds

96 AGRICULTURAL CHEMISTRY

both with the metals and with the elements which enter
into the organic compounds of plant and animal bodies.

Problem i. — How much P2O5 in a ton of bones, 80 per cent.
Ca3(PO,),?

Problem 2. — How much would the P2O5 in a ton of Ca2H2(P04)3
be worth at 5 cents per pound for the PjOj ?

Ca2H2(POj2 = PA + 2CaO f H^O.

CHAPTER XIV
Sulfur and Its Compounds

112. Occurrence. — Sulfur is found free, and in combina-
tion with other elements ; sulfids and sulfates are the
compounds which occur the mo?t abundantly. Sulfur is
also found in small amounts, in combination with carbon,
hydrogen, oxygen, and nitrogen, forming the organic
compounds of plant and animal bodies.

113. Preparation.— When taken from the mines, sulfur
is mixed with impurities, as sand and clay, which are
partially removed by
heating the sulfur, out
of contact with the air,
much in the same way
that charcoal is pro-
duced. The crude sulfur ^'^- 43-Crystals of sulfur.

is refined by vaporizing and condensing the volatile sulfur
upon the surfaces of brick chambers, the product being
known as flowers of sulfur. By drawing off the molten
sulfur into wooden molds, roll sulfur, or brimstone, is
formed.

114. Properties. — I^ike carbon and a few other ele-
ments, sulfur has a number of allotropic forms. It may
assume either an amorphous or several crystalline forms.
It melts at a low temperature, and when molten sulfur is
poured into water, a rubber-like, amorphous mass is
obtained. Sulfur combines with oxygen ; and with the
metals it forms sulfids.

98 AGRICULTURAL CHEMISTRY

115. Uses. — Sulfur is used in the preparation of sulfuric
acid, in the production of vulcanized rubber, in the
manufacture of matches and gunpowder, and for bleach-
ing and disinfecting purposes. A small amount in the
form of sulfates is necessary as plant food.

Experiment ig. — Properties of sulfur. Place 15 grams of
sulfur in a test-tube and heat slowly until it is a thin, amber-colored
liquid. As the heat increases, notice that it becomes darker until
black, and so thick and viscid that it cannot be poured from the
test-tube. Continue to apply heat until slightly lighter in color
and again a liquid. Then pour the sulfur into an evaporating dish
containing water, and, when cold, examine it and describe its proper-
ties. Examine the sulfur product or crystals left in the test-tube,
and compare with the original sulfur, using a lens for the purpose.

Questions, (i) Are the crystals of sulfur formed by fusion like
those of the original powdered form ? (2) How is it possible for
sulfur to assume different ph3-sical forms ? (3) Is sulfur soluble iu
water? (4) What is a sulfate ? Give the formula for one. (5) What
is a sulfite ? Give the formula for one. (6) What is a sulfid ?

116. Sulfur Dioxid. — When sulfur is burned either in
air or oxygen, SO,, a colorless, suffocating, non-combusti-
ble gas is produced. SO^ combines with water, forming
H2SO3, sulfurous acid. Sulfur dioxid is used in bleach-
ing and for disinfecting purposes, as it is alike destruc-
tive to organic coloring- matter and to germ life.

Experiment 20. — Sulfur dioxid. Fill the deflagration spoon
half full of sulfur ; ignite, and then lower into a small cylinder con-
taining a piece of wet colored cloth and a piece of wet blue litmus
paper. As soon as the sulfur ceases to burn, remove the spoon and
cover the cylinder with a glass plate.

Questions. ( i ) What reaction does the SO2 give with the litmus
paper? (2) What effect does it have upon the cloth? (3) What
does the SO2 form with H^O ? (4) Is SO^ a heavy or light gas ? (5)

SULFUR AND ITS COMPOUNDS 99

Is it a chemically active substance? (6) Why does it act as a
bleaching agent ? (7) Why is it valuable as a disinfectant ?

117. Sulfuric Acid.— Sulfuric acid can not be produced
from sulfates as H CI and HNO3 were produced from their
salts, because there is no acid or other material that can
be used economically for the purpose. H^SO^ is made
from its elements by the use of an oxidizing agent. The
different steps in its production are :

(i) Burning of sulfur, or roasting of some ore, as
pyrites, which contains sulfur. The S forms with O, SOg.

(2) Union of SOj and HjO, forming sulfurous acid,
H,S03.

(3) Oxidation of H^SOj to form H.^SO^. This is accom-
plished by the use of NO^ reduced to NO, which in turn
is capable of uniting with the oxygen of the air, re-
forming NOj. NO is used as a carrier of O ; hence the
oxygen of the air is used indirectly for the oxidation
of H2SO3. The different reactions take place simulta-
neously in lead-lined chambers :

SO2 + H,0 + NO, = U,SO, + NO.
NO + O = N

Other and more complicated reactions also take place.

The crude acid is then concentrated and purified. Sul-
furic acid is extensively used in industrial operations.
There is scarcely a chemical product in the preparation of
which HjSO^ has not been used either directly or in-
directly. H2SO4 takes an important part in the manufac-
ture of soda, which, in turn, is used for making glass; in
the preparation of commercial fertilizers, and of many
food products. The amount of sulfuric acid which a

lOO AGRICULTURAI, CHEMISTRY

country consumes is a fair index of the extent of its
manufacturing industries.

ii8. Properties of H^SO^.— When pure it is a colorless,
heavy, oily liquid. It has a strong afl&nity for water,
with which it combines with evolution of heat. It will
decompose organic materials containing C, H, and O,
liberating the H.fi as water, with which it combines,
while the carbon, which is partially oxidized, separates
and blackens the acid. When sugar is acted upon by
concentrated sulfuric acid, this change takes place.
HjSO^ is used in the laboratory for drying gases, for
drying the air in desiccators, and for oxidizing purposes,
as in the determination of organic nitrogen in food mate-
rials. It is one of the most useful and extensivel used
of any of the reagents in the laboratory.

Experiment 21. — Make the followiug tests with some of the
sulfuric acid from the reagent bottles : (i) Put 2 or 3 cc. H^SO^
into a test-tube ; thrust a splinter of wood into it and leave it there
for a few minutes. Then remove the splinter from the test-tube.
Wash off the acid and examine the splinter. (2) Place in an
evaporating dish 5 cc. water and 15 cc. H2SO4. Stir it with a small
test-tube containing i or 2 cc. NH^OH. Observe that the heat
generated by the action of the H2SO4 and water, volatilizes some of
the NH3. (3) Put 10 cc. of water and i cc. of H.,S04 into a test-
tube. Then add 2 or 3 cc. of barium chlorid, BaClj. Observe the
result.

Questions, (i) Why is not H^SO^ made from sulfates? (2)
Why is heat produced when water and H2SO4 are mixed? (3)
What use was made of this heat in test No. 2? (4) What caused
the precipitate when BaCl.^ was added? (5) Write the reaction.
(6) What is the name of the product formed ? (7) What are some
of the uses of H2SO4 ? (8) How many kinds of salts does H2SO4

SULFUR AND ITS COMPOUNDS lOI

form ? (9) Why is nitric oxid used in the manufacture of H2SO4 ?
(10) What are the physical properties of H.^SO^? (11) Of what
agricultural value is H.^SO^ ? (12) Does HjSOj dissolve lead ? (13)
Why does commercial HjSO^ often appear dark-colored or deposit
a fine white sediment ?

119. Sulfates. — Sulfuric acid is a dibasic acid, and
hence may form two series of salts, as NaHSO^, primary
sodium sulfate (acid sodium sulfate), and NajSO^, second-
ary sodium sulfate (normal sodium sulfate). The sul-
fates of the metals form a large class of compounds which
vary in chemical and physical properties according to the
metal that is present. The sulfates as a class are fairly
stable compounds ; some, as sodium and potassium sul-
fates, are soluble ; others, as calcium sulfate, are sparingly
so while barium sulfate is one of the most insoluble sub-
stances in nature. Many of the sulfates contain water of
crystallization. Some, as calcium and potassium sulfates,
are valuable as fertilizers, while others, as copper sulfate,
are used as fungicides.

120/ Sulfids. — Sulfids are compounds of. the metals
with sulfur, as K^S, FeS, and CuS. When a sulfid, as
FeS, is treated with a dilute acid, H2S, hydrogen sulfid,
is liberated. FeS -f 2HCI = FeCl, + H,S.

The differences in solubility and other properties of the
sulfids are taken advantage of in the separation and
identification of the metals. H^S is formed when albu-
minous matter, as the white of an egg, decays. It is also
present as one of the gases given off from sewers. It is a
poisonous, suffocating gas.

Experiment 22. — Hydrogen sulfid. (This experiment should

I02

AGRICULTURAL CHEMISTRY

be performed under the hood). Arrange the apparatus as
shown in Fig 44. The delivery tube and cork should fit tightly,
and the deliveiy tube should pass into a test-tube containing 10 cc.
of Pb(N03)2 solution. Test-tubes containing 10 cc.
respectively of NaCl, and CUSO4 solutions should
be conveniently at hand. Place 5 grams of pul-
verized FeS in the generating test-tube, add 10 cc.
dilute HCl, and immediately connect with the de-
livery tube. After the gas has passed through the
lead nitrate solution, for a couple of minutes, pass
it through the sodium chlorid and copper sulfate
solutions ; then allow a little of the gas to escape
into a cylinder containing water. Do not allow
the free gas to escape in the room. With NaCl no
insoluble sulfid is formed.

Questions. ( i) What is the odor of the gas ? (2)
Write the equation for its production. (3) What
was formed when the gas was passed into PbCNOj).^?
Write the reaction. (4) What was formed when
the gas was passed through Cu(N03)2? Write the
Is HjS soluble in water? (6) When albumin decays,
(7) Why was no precipitate

Fig. 44. — Hydro
gen sulfid gen
erator.

reaction. (5)

from what is the H2S produced ?

formed when the gas was passed through NaCl ?

Problem /.—How much HjSO^ can be made from one ton of sul-
fur?

Problem 2. — What per cent, of H^SO^ is SO3 ?

Problem j.— How much H2SO4 is required to neutralize 500
pounds NaOH ?

CHAPTER XV
Silicon and Its Compounds
121 Occurrence. — Silicon is found in nature in com-
bination with oxygen as silica, Si02; and with oxygen
and the metals as silicates. It is never found free but al-
ways in combination with other elements. Next to
oxygen it is the most abundant element found in nature.
In the form of silicates it is the basis of the composition
of nearly all rocks, and in the soil SiO.^ is found to the
extent of from 60 to 90 per cent. It is present in the
ash of plants and, to a slight extent, in animal bodies.

122. Preparation and Properties. — Silicon is separated
from its compounds with difficulty. By treatment in an
electric furnace, quartz or SiOj is reduced.
Like carbon, silicon has crystalline and
amorphous forms. Pure quartz, SiO^,
and other forms of silicon, are insoluble
in nitric, hydrochloric, and sulfuric acids.
When acted upon by hydrofluoric acid,
silicon tetrafluorid, a gas is formed.

Fig- 45-
SiO^ + 4HF = SiF, + 2H,0. HF is Quartz crystal.

used extensively for the decomposition of silicates.

123. Silicic Acid. — When SiO^ is fused with the hy-
droxids or carbonates of potassium or sodium, potassium
or sodium silicate is obtained :

SiO, -H K,C03 r= K,Si03 + CO,.
SiO, + 4KOH = K.SiO, + 2H,0.
The silicates of potassium and sodium are soluble in

I04

AGRICULTURAL CHEMISTRY

water, and are commonly called water-glass. Some of
the silicates are soluble in acids, but most of them are
insoluble complex compounds which are difi&cult to de-
compose.

When K^SiO^ is treated with HCl, a gelatinous mass
containing silicic acid is obtained : K^SiO^ + 4HCI =
H.SiO, + 4KCI.

H^SiO^ is normal silicic acid. Upon exposure to the
air it loses a molecule of water and forms ordinary silicic
acid, H2Si03, which is decomposed by heat and in the
presence of acids forms H^O and SiO^.

In addition to the two silicic acids, H^SiOg and H^SiO^,
there are other forms known as polysilicic acids as :
HjSi^O^, H^SigOg, and H^SiaOg, obtained by removing
water from the normal and ordinary silicic acid.
2H,Si03 = H.Si.Oj + H,0.
3H,SiO, = H.SigOs + 4H,0.
124. Dialysis. — In the preparation of silicic acid, the
process known as dialysis is employed for dissolving and
removing the impurities. Some sub-
stances, as NaCl and HCl, dissolve
and readily pass through animal mem-
brane ; such substances are called
crystalloids, while bodies like silicic
acid, which do not penetrate animal
membrane, or do so very slowly, are
called colloids. The removal of the
HCl from the solution containing the
gelatinous silicic acid is accomplished by means of the
dialyzer. Fig. 46. This property of materials, readily or

Fig. 46.— Dialyzer.

SILICON AND ITS COMPOUNDS I05

slowly to diffuse through animal membrane, is a physical
characteristic, and is occasionally made use of for wash-
ing and separating compounds.

125. Silicates. — Since silicon forms such a variety of
acids, the number of silicates found in nature is very
large. The hydrogen atoms of silicic acid can be re-
placed with different metals, forming double salts, as
AlKSigOg, which is feldspar, or the double salt of trisilicic
acid, H^SijOg. This renders the composition of the sili-
cates exceedingly complex. Many of the silicates con-
tain also water of hydration as part of the molecule ; as
aluminum silicate or pure clay, Al^(SiO^)3.H20. Since
rocks are composed mainly of silicates, and soils are
formed from the decay of rocks, it follows that soils are
practically a mechanical mixture of silicates with small
amounts of other compounds. Hence, the importance of
the subject of silicic acid and the silicates. Unfortunately
the structure and composition of the silicates have not
been determined as completely as of other salts and
acids. Pure clay is aluminum silicate, formed from the
disintegration of feldspar rock, a double silicate of potas-
sium and aluminum. Mica, hornblende, and zeolites
are all complex forms of silicates.

126. Importance of Compounds of Silicon. — The com-
pounds of silicon, as silicon dioxid, SiO^, and of the sili-
cates, are used in the manufacture of glass, porcelain and
brick. The element itself takes no direct part in animal
or plant life, but indirectly is important, for it is in
combination with many elements which serve as plant
food. Some of the simpler and more soluble silicates are

Io6 AGRICULTURAL CHEMISTRY

capable of being acted upon by decaying animal and
vegetable matter and undergoing chemical changes which
prepare them for plant food. Since silicon forms the
principal acid element which enters into the composition
of rocks, soils, building stones, glass, brick, and porcelain,
and is associated with the elements in the soil which serve
as plant food, it follows that it is an important element in
industrial operations and in agriculture.

Experiment 2j. — To about 5 cc. of sodium silicate in a test-tube
add a few drops of HCl and observe the result. Then add NaOH
and observe the result. Add more HCl, and evaporate the ma-
terial to dryness in the evaporating dish. When cool, test the
solubility of the residue in water.

Questions, (i) What was formed when HCl was added to
sodium silicate ? Write the reaction. (2) What was the appearance
of the above product ? (3) What effect did the NaOH have, and
what was formed ? (4) What was formed when the material was
evaporated to dryness? (5) What can you say as to the solubility
of the product ?

Problem /.—What per cent, of SiO, in clay, Al4(SiOj3.H20?

Problem 2. — How nmch silicic acid is formed when 10 grams of
HCl act upon K^SiO^ ?

CHAPTER XVI
Oxids of Carbon, Carbonates, and Carbon Com-
pounds

127. Carbon Dioxid. — Carbon dioxid is obtained from
the combustion of carbon and also from the treatment of
a carbonate v/ith an acid. A carbonate is a salt of car-
bonic acid, M2CO3, in which M represents any mono-
valent metal, as K or Na. Calcium carbonate, CaCOs, is
the most abundant carbonate found in nature. When a
carbonate is treated with an acid COj is liberated, and a
salt is formed, as

CaCOs + 2HCI = CaCl^ + CO, + H,0.

Experiment 2^. — Preparation of carbon dioxid. Arrange the
apparatus as for the preparation of hydrogen. Put 10 grams of
marble, CaCOg, into the Woulff bottle, and sufficient water to
cover the end of the thistle tube. Fill 2 or 3 cylinders with water
for collecting the gas, which is only slightly soluble in water, then
add slowly, through the thistle tube, about 20 cc. concentrated
HCl. Allow a little of the first gas generated to escape into the
room and then collect 2 or 3 cylinders of CO,. Remove the cylinders
from the pneumatic trough and place them on the desk, right side
up. Now remove the delivery tube from the pneumatic trough
and allow the gas to pass into a test-tube containing about 10 cc. of
clear lime water, Ca(0H)2. If necessary, add through the thistle
tube a little more acid to the generator. Observe the white precipi-
tate formed in the test-tube. Let the gas pass through the lime
water for several minutes, until the solution becomes clear. Now
boil the solution and observe the reappearance of the white precipi-
tate. Test some of the escaping gas with a burning splinter.
Pour a receiver of the gas over a candle or a low gas flame, and
observe the result. Thrust a burning splinter into a cylinder of

I08 AGRICULTURAL CHEMISTRY

COj. Observe the result. Add 5 cc. water to the cylinder in which
the splinter was placed, and then a little lime water ; shake, and
observe the result.

Questions, (i) Write the reaction for the preparation of CO2.
(2) What is a carbonate? (3) Is CaCOg soluble in pure water?
(4) Is it soluble in water containing CO.,? (5) What caused the
precipitate to form when the CO2 gas was passed through the lime
water? (6) What is this precipitate? Write the reaction. (7)
What caused this precipitate to disappear when more gas was
passed through the solution? (8) What caused it to reappear
when the solution was boiled? (9) What caused the candle to be
extinguished when a receiver of COj was poured over the flame?
(10) O is a supporter of combustion ; CO2 contains O ; why does
CO2 not support combustion ? (11) Is COj a heavy or a light gas,
and what tests indicate that it is heavy or light? (12) What other
carbonate could be used for making CO2? (13) What other acid
could be used for making COj ?

128. Carbon Monoxid.— Carbon monoxid is formed
when carbon is only partially oxidized because of an in-
sufficient supply of air. In a coal stove, for example,
there is not a perfect supply of air in the interior of the
burning mass ; carbon monoxid is formed there and passes
to the surface where it burns as a blue flame. If the
draft is imperfect, a large amount of carbon monoxid is
formed. When a coal stove gives off gas, the carbon
monoxid is not oxidized, but is thrown off into the room.
Carbon monoxid is a light, colorless, combustible, poison-
ous gas, and can be produced by subjecting highly heated
carbon to the action of steam. The reaction is
C + H2O = CO + 2H. Both CO and H are combustible,
and when they are enriched by some of the hydrocarbons,
so as to introduce materials for producing light, when
burned, they may be used for illuminating purposes, and

OXIDS OF CARBON, CARBONATES, ETC. I09

the product is called water-gas. Carbon monoxid is pro-
duced in furnaces from the coke, which is mixed with ore,
and in the smelting and refining of ores, carbon monoxid
is an important reducing agent ; in fact, it is the main
reducing agent of the blast-furnace.

129. Marsh Gas (Methane, CHJ. — When vegetable
matter decays under water, where the supply of air is
incomplete, methane, CH^, is one of the products formed.
It is given off in bubbles from the surface of stagnant
pools. It often collects in coal mines, and is there called
fire-damp. CH^ can be prepared in the laboratory in a
number of ways, and is a colorless, combustible gas,
which with air forms an explosive mixture.

130. Hydrocarbons. — A compound, as methane, com-
posed of hydrogen and carbon, is called a hydrocarbon.
There are a large number of such compounds, forming
series in which the members differ from one another
in composition by a definite number of C and H atoms,
as methane, CH^, and ethane, QHg. The next mem-
ber is propane, CjHg; CHg being the common difference
between the members of this series. By oxidation, re-
duction, and substitution, in which a part of the H is re-
placed with equivalent radicals, a large number of de-
rivatives, as alcohols, aldehydes, ethers and organic
acids, are formed.

131. Petroleum. — Petroleum is an oily liquid obtained
in some parts of the world by boring wells into the rock
strata in which it is found as a natural product. It is
a mechanical mixture of various liquid and solid hydro-

no

AGRICUI.TURAL CHEMISTRY

carbons, often accompanied with gaseous hj'drocarbons.

The hydrocarbons distilled off at a low temperature, rang-
ing from 8° to 68° C, form
the gasoline and benzine prod-
ucts, while those which distil
between 175° and 215° C. form
the various grades of kerosene.
In the preparation of gasoline,
benzine, and kerosene, the sep-
aration of the various grades
of hydrocarbons is not com-
plete ; kerosene, for example,
maj' contain traces of either
gasoline or paraffin products.
Kerosene should have a flash-
ing-point not below 44° C.
(111° F.), in order to render
*©it safe for illuminating pur-
poses. The flashing-point of
kerosene may be approxi-
mately determined in the fol-
lowing way :

Experiment 25. — Testing kero-
sene. Pour into a small porcelain
crucible some kerosene ; place the
crucible upon a water -bath, and sus-
pend a thermometer in the kerosene.
Do not allow the water in the bath
to come in contact with the cruci-
Fig. 47.— Testing kerosene. ^^-^^ qj. ^jjg thermometer to touch the

bottom. Cautiously heat the water until the thermometer registers
40° C, then remove the lamp and draw a lighted match across the

OXIDS OF CARBON, CARBONATES, ETC, III

surface of the kerosene. If it flashes, note its temperature ; do not
let it burn ; should this occur, remove the thermometer and cover
the crucible. If the kerosene does not flash, repeat the test and if
necessary apply more heat until the flashing-point is reached. Cal-
culate the corresponding temperature on the Fahrenheit scale.

132. Use of Gasoline. — Gasoline is perfectly safe for
use as a fuel, provided a few simple precautions are ob-
served : (i) Never u.se a gasoline stove when there is
but little gasoline in the tank, because the last gas gen-
erated is mixed with air, and is liable to form an explo-
sive mixture. (2) All joints and connections about the
stove should be tight to prevent escape of gasoline into
the air. I^ack of care in this respect is the most frequent
cause of fires. (3) The gasoline can should be well
corked and stored in a cool place. (4) The stove should be
kept clean, and no deposit of carbon should be allowed to
collect upon the burners.

133. Illuminating Gas. — Illuminating gas is made from
soft coal and petroleum by destructive distillation. The
gases formed are washed and separated from ammonia
and coal-tar, and consist of various hydrocarbons which
are used for illuminating purposes. The coal, after being
deprived of its gaseous products, is converted into coke,
which bears the same relation to coal which charcoal bears
to wood. The ammonia and coal-tar are recovered as by-
products. Various coloring-matters are made from coal-
tar.

If air is forced through gasoline in a confined chamber,
or if gasoline is vaporized, it will burn like ordinary coal
gas. Gasoline can be vaporized on a small scale, and

112

AGRICULTURAL CHEMISTRY

machines suitable for the purpose are made for illuminat-
ing dwellings. Five gallons of gasoline will produce about
looo feet of gas or vapor. The illuminating power of
gas, and of flames in general, is expressed in terms of
candle-power. A sixteen candle-power light is one that
gives sixteen times as much light as a standard candle,

Fig. 48. — Illuminating gas plant for producing gas from gasoline. A, weight
to air-pump B. D, carburetter or generating tank into which air is forced.

composed of spermaceti, and burned at the rate of 120
grains per hour, the comparison being made by means of
a photometer. In some localities, hydrocarbons, due to
decomposition of organic matter, are given off from the
earth as natural gas in amounts sufficient to be used for
illuminating and fuel purposes.

134. Mineral Oils. — The heavier products obtained in

OXIDS OF CARBON, CARBONATES, ETC. II3

the distillation of petroleum, after the removal of the
gasoline, benzine, and kerosene, are used for lubricating
purposes, and are called mineral oils. They have a boil-
ing-point from 250° to 350° C.

135. Oil of Turpentine (CioHjg). — Oil of turpentine is
obtained by distilling the resinous material which exudes
from incisions in certain species of pines. Resin is ob-
tained in the retorts. Oil of turpentine is inflammable,
and dissolves readily in ether, alcohol, and naphtha. It
is a valuable solvent, extensively used in the preparation
of varnishes and paints, and as a solvent for caoutchouc.
Turpentine belongs to the class of compounds known as
essential oils.

136. Creosote. — When wood tar is distilled, various
products are obtained which, after treatment with chemi-
cals for purification, are called wood-tar creosote. This
is a yellowish liquid with a smoky odor. It is a power-
ful antiseptic, and is the preservative employed in the
preparation of " smoked meats," as haras and fish. It
has no marked action on albuminous matter and in small
amounts is not poisonous. Because of its antiseptic powers,
wood creosote is used extensively for the preservation of
wood, as it prevents decay. When some kinds of wood,
as beech wood, are burned, the wood-tar condenses in
the chimney.

137. Benzine or Benzol (CgHJ. — When coal tar, ob-
tained in the manufacture of illuminating gas, is sub-
jected to fractional distillation, commercial products are
obtained known as coal tar, naphtha, middle oil, heavy

114 AGRICULTURAL CHEMISTRY

oil, anthracene oil, and pitch or artificial asphaltum. The
naphtha or light oil consists of a mixture of hydrocar-
bons, benzine being among the number. Benzine is ex-
tensively used as a solvent for fatty bodies. It is a very
inflammable liquid.

i38. Aliphatic and Aromatic Series of Compounds. —
In organic chemistry benzine occupies an important posi-
tion, as the direct treatment of benzine and its deriva-
tives, produces the aromatic series of compounds, which
form one of the two main divisions of the subject. The
other is obtained from methane and its derivatives,
and constitutes the aliphatic series. The alcohols, ethers,
glycerides, fatty acids, organic acids, carbohydrates, and
amids, are members of the aliphatic series, while essen-
tial oils, coloring- matters, and mixed nitrogenous com-
pounds, are members of the aromatic series. In or-
ganic chemistry, a study is made of the formation,
relationship, structure, and properties of all these com-
pounds. Hence the importance of this branch of chem-
istry.

139. Carbon Disulfid. — With sulfur, carbon forms car-
bon disulfid, CS2, a clear liquid with a characteristic odor.
It readily burns and is easily vaporized. It is a solvent
for fats, resins, sulfur, and iodin, and is used for the de-
struction of insects, particularly those infesting grains,
and for killing small burrowing animals, as gophers.

140. Cyanids. — In the presence of metals carbon unites
indirectly with nitrogen, forming cyanids as KCN. When
mercuric cyanid is heated, cyanogen gas and metallic
mercury are formed : HgCCN)^ = Hg -f- 2CN. Cyano-

OXIDS OF CARBON, CARBONATES, ETC. II5

gen and the cyanids are very poisonous. With H, cyano-
gen forms hydrocyanic acid, which is used for the destruc-
tion of scale insects and in the preparation of pigments.

141. Carbids. — With some of the metals, notably cal-
cium, carbon forms carbids, as CaC,, which is produced
by the fusion of coke and limestone in electric furnaces.
In the presence of water CaC^ is decomposed, forming
acetylene gas, C^Hj, and calcium hydroxid.

CaC, + 2H.X) =- C,H, -\- Ca(OH),.
Acetylene generators are prepared for illuminating
dwellings. Acetylene, like all gaseous hydrocarbons, as
methane and benzine, forms explosive mixtures with oxy-
gen. All illuminating gases should be dealt with as
highly combustible and explosive materials.

142. Fuels. — There are three forms of fuel : ( i ) gas,
(2) liquid, and (3) solid. Natural gas, coal gas, and gas
generated from gasoline and naphtha, are the principal
forms of gas fuel ; kerosene, gasoline, and crude petro-
leum are liquid fuels, while coal, coke, lignite, peat, and
wood are the chief forms of solid fuel. The composition
of coal, coke, lignite, and peat, is discussed in Chapter V.
Wood is composed largely of cellulose, and contains, when
dry, about 50 per cent, carbon, 6 per cent, hydrogen, and
43 to 44 per cent, oxygen. Air-dried wood contains from
10 to 15 per cent, moisture. Different kinds of wood
vary in density between quite wide limits ; for example,
a cord of dry pine weighs about 3000 pounds, while a
cord of dry maple or other hard wood weighs from 4500
to 5000 pounds, or more. Hence the same volume (as a
cord) of soft wood yields less total heat than a cord of

Il6 AGRICULTURAL CHEMISTRY

hard wood, but a pound of the different kinds of wood
gives nearly the same amount of heat. The amount of
heat which a material produces when burned is measured
in the calorimeter, and is given in terms of calories or
heat units. The presence of water in fuels lowers their
caloric value, because it requires a definite amount of
heat to evaporate and expel as steam the moisture before
combustion can take place.

143. Caloric Value of Fuels (Comparison made on
basis of equivalent weights).

Calories. Calories.

Perfectly With Per cent, of

dry. water. water.

Hard coal 9160 8690 2.63

Soft coal 7664 7128 5.02

Pine (red) 5997 5155 13.83

Cedar 5974 5031 14.09

Maple 5978 5117 12.49

Birch 5978 4758 21.70

144. Foods. — The materials used as human and animal
foods are mechanical mixtures of various organic com-
pounds, as starch, sugar, fat, albumin, etc., together
with various mineral salts. The composition of the or-
ganic compounds of foods forms a part of the study of
organic chemistry , while their economic value and the uses
made of them by the body, are studied in physiological
chemistry. Knowledge in regard to the composition and
uses of foods, particularly of human foods, is somewhat
limited, although along this line, many facts and laws of
economic and sanitary importance have been discovered.
The subject of foods is treated more fully in the chap-
ters relating to the chemistry of foods.

OXIDS OF CARBON, CARBONATES, ETC.

117

Vegetable foods and fuels are alike in chemcal com-
position, and serve somewhat the same functions,
but in different ways. Food is used as fuel by the body,
and also for the renewal of old and the production of new
tissues. The heat produced from food is transformed
into muscular and other forms of energy ; the heat from
the combustion of fuel is converted into chemical energy,
which is utilized for mechanical purposes.

145. Production of Organic Compounds in Plants. —
The carbon dioxid of the air is the source of the carbon
used by plants
for the produc-
tion of the
various organic
compounds
found in vegeta-
ble substances,
and since about
50 per cent, of
the ash-free tis-
sue of plants is
carbon, it fol-
lows that the
carbon dioxid
of the air is an
important fac-
tor in plant
growth. Hydrogen and oxygen are obtained from
the water of the soil which is received from the
air. The production of the various organic corn-

Fig. 49. — Production of organic compounds in plants,
showing sources of plant food.

Il8 AGRICULTURAI, CHEMISTRY

pounds of plants takes place in the cells of the
leaves, and is the result of chemical changes induced by
life processes. In order to promote cell activity, sun-
light and a suitable temperature are necessary. The
sun's rays take an important part in promoting chemical
changes in the leaves of plants. In addition to carbon
dioxid, water, heat, and sunlight, various mineral ele-
ments in the form of compounds of potassium, calcium,
phosphorus, nitrogen, iron, magnesia, sulfur, and pos-
sibly of a iew others are required as plant food. Without
these essential elements and requisite conditions, the
growth of crops cannot take place. It often happens that
soils are unproductive because of the absence, in available
form, of some of the elements essential for plant life.
The production in the leaves of plants of the various or-
ganic compounds, as cellulose, starch, sugar, fat, albu-
min, etc., and a few of the complex chemical changes
which take place, have been studied.

146. Decay of Organic Compounds. — All organic com-
pounds, particularly those found in the tissues of plants
and used as food, are subject to chemical change com-
monly called decay. Such change is nearly always pro-
duced as the result either of the action of organized fer-
ments, or of the chemical products known as chemical
or soluble ferments. Fermentation changes and decay
take place whenever cell activity becomes feeble or
ceases ; then the material becomes food for micro-organ-
isms. Many chemical changes take place as the result of
fermentation ; some of these are necessary in plant and
animal nutrition. If the chemical changes, coordinate

OXIDS OF CARBON, CARBONATES, ETC.

119

^

■^

I

^

"

■!

'

-.

,

;

;t

-

t

r ft

j :;

( ••

:0,

• ft

• c

',

:

-

>T."«y:'-

\/

with fermentation, are uninterrupted, the organic mate-
rials are decomposed until carbon dioxid, water, ammonia
gas, and hydrogen sulfid are ob-
tained as the final products.
When such changes take place,
the mineral matter combined and
associated with the organic mat-
ter is left as non-volatile products.
In economic agriculture, it is the
aim to conserve and return to the
soil these essential elements, as
nitrogen, potassium, phosphorus,
and calcium, which are fre-
quently unavailable or present in
scant amounts in soils, so that • t. vl.. -.\ •.•-■... •»..'•■
the fertility will not be impaired. ^^s- so-oecay of wood.
The elements present in plant and animal bodies pass
through a cycle of chemical changes ; they are never lost
to nature, but appear in different chemical compounds, as
exemplified by the law of indestructibility of matter.
A. Elements of plant growth in soil and air.

B. Elements from soil and air elab-
orated into plant tissue.

C. Elements in plant tissue elab-
orated into animal tissue.

The elements in either plant or ani-
mal bodies may pass back to A, and
then pass again through the same
cycle of chemical changes.

CHAPTER XVII
Writing Equations

147. Importance. — A chemical equation expresses con-
cisely the changes which take place when two or more
compounds are brought together so as to react, or when
a material is acted upon by any agent which causes a
chemical change. When chemical equations are under-
stood by the student, they are of great assistance, as they
necessitate a knowledge of the laws of valence, of the
power of replacement, and of the properties of the ele-
ments and their compounds.

148. Common Errors in Writing Equations. — Some
of the more common errors in writing equations are :

(i). Failure to use correct formulas.

(2). Failure to use the correct number of parts of com-
pounds, radicals, or elements.

{3). Failure properly to balance the equation.

(4) . Failure to form reasonable compounds or products.

If the correct formula, or the right number of mole-
cules is not used, the equation is incorrect, it cannot be
balanced, and the principle represented by the sign of
equality is violated. There should be as many atoms of an
element on one side of an equation as on the other. In
order properly to balance an equation, as many mole-
cules of the compounds on the left of the equation should
be taken as are needed to satisfy the valences of the re-
acting elements and radicals. In the equation
AgNOs + HCl = AgCl + HNO3,

WRITING EQUATIONS

121

only one molecule each of AgNOg and HCl is necessary,
because all of these elements and radicals are monova-
lent. A simple exchange takes place in which the H of
the acid is replaced by the metal Ag. If the elements H
and Ag were to exchange places, they would occupy,
after the exchange, the positions shown on the right-hand
side of the equation. This exchange is represented
graphically in Fig. 52 ; A represents the order before,
and B after the reac-
tion. Blocks of ,.

^

H'

CI'

^<^~^

/

A£'

no:

A^'

CI'

V

H'

no;

wood marked to rep- ■*
resent the elements
and radicals can be
used, the block marked B

^ i^ •' Pig. 52. — Graphic illustration of a chemical

the equivalent block reaction.

marked Ag. When diflSculty is experienced in writing
chemical equations, this method of illustration will be
found helpful.
In an equation as

2NaCl + H,SO, = Na,SO, + 2HCI,
where both monovalent and bivalent elements and rad-
icals are present, it is necessary to take two molecules
of NaCl because there are two H atoms to be replaced.
H and Na have the same valence, viz. , i , and SO^ has a
valence of 2. In order to obtain two atoms of Na, it is
necessary to take 2NaCl ; then two atoms of Na replace
two of H. The products are Na.SO, and 2HCI. SO, is
a radical with a valence of 2 and requires 2Na atoms in
order to form a compound. A similar reaction is repre-

122

AGRICULTURAL CHEMISTRY

sented graphically by the use of blocks in Fig. 53. A
represents the arrangement before, and B the arrange-
ment after the reac- ___-=

K'

K'

no:

no!

B

K'

so:

K'

-f'

H'

no;

H'

no;

tion. Observe that in 1 p —

this equation there is H'

the same number of A I 1 SO!'

atoms of each element H

on each side of the v.

equation. After writ- y~

ing an equation the
student should always
observe whether or
not it is properly bal-
anced, and that rea- Fig. 53.
sonable products are
formed. The valences of the elements and radicals are
given in Sections 15 and 77.

There are always as many parts by weight of the ele-
ments on one side of an equation as on the other. That
is, the sum of the weights of the atoms and molecules on
one side is equal to the sum of those on the other, as :

-Graphic illustration of a chemical
reaction.

2NaCl +
2Na ^ 46
2CI =71

117
117 +

H3SO,

2H= 2

S =32
4O =64

: 2HCI
2H -= 2
2CI =71

73

+

Na.,SO,.
2Na = 46
S = 32
4O = 64

215-

142
73 + 142 = 215.
In the case of trivalent and bivalent elements ind radi-
cals, as in the reaction between HgPO^ and Ca(^0H)2, it

WRITING EQUATIONS 1 23

is necessary to take 2H3PO4 and 3Ca(OH)2, in order to
make the equation balance. The Ca and H atoms ex-
change places ; there are three H atoms to be replaced.
Ca has a valence of 2 ; i Ca cannot replace 3H, but
6H(2H3) can be replaced by 3Ca, because 2H3 has a total
valence of 6 and so has 3Ca.

2H3PO, + 3Ca(0H), = Ca3(P0J, + 6H,0.

3Ca atoms replace the 2H3 and form Ca3(PO^)2, a bal-
anced compound, because PO^ is a radical having a valence
of 3, and if taken twice its total valence is 6, with which
3 Ca atoms can combine. The remaining H and O atoms
form 6H2O.

149. Impossible Reactions. — Not all chemical com-
pounds when brought together give a chemical reaction.
Whether or not a reaction takes place can be determined
only after a careful study of the elements and their prop-
erties ; this often involves a more exhaustive knowledge
of chemistry than can be obtained from an elementary
study of the subject.

In the case of BaSO^ + 2HCI, no reaction can take
place, although an apparently correct reaction can be
written :

BaSO, + 2HCI = BaCl^ + H^SO,.
This is because BaSO^ and HCl are the products of the
reaction

BaCl^ + H^SO, = BaSO, + 2HCI.
In the equations given at the end of this chapter a reac-
tion takes place in each case.

124 AGRICULTURAI, CHEMISTRY

150. A Knowledge of Reacting Compounds and Prod-
ucts Necessary. — In order that the writing of chemical
equations may become more than a mere mechanical op-
eration, the student should study the character and prop-
erties of the compounds used and of the products formed.
If one of the compounds is an acid and the other a base,
the subject of neutralization is illustrated. If one of the
compounds is an acid and the other a metal, the re-
placement of the H of the acid occurs. Should one of
the compounds be an acid and the other a salt, an equiva-
lent amount of the H is replaced by the metal or basic
element of the salt. Other principles and laws should
be observed by the student in writing equations. The
character of the compounds, as acid, base, or salt, with
their names, forms a part of equation work, which is an
essential feature of elementary chemistry.

151. Equations for Class Room Work. — The student
should write the following equations :

1. CaCl, + Na.COa =

2. CaCl^ + Na.SO, =

3. Ca(OH), + H,SO,=

4. CaC03-f HC1 =

5. MgC03 + HCl =

6. KN03 + H,S0,=

7. CaCl, + Na3(P0,) =

8. PbCNOj)^ + 2HCI =

9. AICI3 + NH.OH =

10. Ba(OH), + H,SO,=

11. BaCl, + H,SO,=

12. Pb(N03), + H,S0,--

WRITING EQUATIONS 1 25

13. Na,C03 + H,S0,=

14. NajPO, + H^SO, =

15. Ca(OH\ + Na,SO,=

16. Fe(0H)3+H,S0,=

17. (NHJ,SO,+ Ca(OH),=

18. NH,N03 + H,SO, =

19. (NH,),C03 + HC1 =

20. NH.Cl + H,SO, =

21. NH,Cl + Ca(OH),=^

22. NH.Cl + NaOH =

23. NH,Cl + Ba(OH),=

24. NH,N03 + Ca(0H),=

25. NH,0H+HC1 =

26. NH,N03 + K0H =

27. FeCl, + NaOH =

28. FeCl, + NH,OH =

29. AgCl + NaOH =

30. NaX03 + Ba(0H),=:

31. Na,C03 + HCl =

32. NaOH + FeCl,=

33. AgN03 + NaCl =

34. AgN03+HCl =

35. Ca3(PO,), + 3H,SO,=-

36. CaCOg + heat =

37. CaO + CO,=

38. Ca(OH), + CO,=

39. K + H,0 =

40. A1K(S0,), + 3KOH =

41. A1NH,(S0,), + NH.OH

42. CaCl,+ (NHJ,C03-

126 AGRICULTURAL CHEMISTRY

43. CaCl, + H,SO,=

44. Na,Si03 + HCl =

45. CaSi03 + Na,C03 =

46. C + CuO =

47. 3Cu + 8HN03 =

48. C,H,A+i20 =

49. AlCl3 + H3PO,=

50. AICI3 + NH.OH =

CHAPTER XVIII
Potassium, Sodium, and Their Compounds

153. Occurrence of Potassium. — Potassium is found in
nature largely in combination with silicon and other ele-
ments, forming silicates, which undergo slow disintegra-
tion with liberation of potassium salts which become food
for plants. Potassium is present in the ash of all plants
and food materials and is one of the elements required by-
crops. In some " alkali" soils, small amounts are found
in the form of potassium salts. Deposits of various
double salts of potassium, supposed to have been formed
by crystallization from sea-water, are found at Stassfurt in
Prussia, and are commonly known as Stassfurt salts. These
are the chief source of the potassium compounds, some of
which are extensively used in the preparation of fertilizer.

The element potassium is most typical of all the base
elements as a class. It is never found in nature in
a free state, but always in combination with other ele-
ments from which it is separated with difficulty. It is a
light substance with a metallic luster, and in the labora-
tory is kept out of contact with air and water, with which
it readily reacts.

153- Potassium Hydroxid. — This is a strong basic
compound extensively used in the laboratory and in
manufacturing operations. It is prepared by treating
K.COj with Ca(OH)„ the reaction being K^COj +
Ca(OH), = CaC03+ 2KOH. CaCOj is insoluble and
can be separated by filtering from KOH which is soluble.

128

AGRICULTURAL CHEMISTRY

KOH, commonly called caustic potash, is a white, brittle
substance which readily absorbs moisture and carbon
dioxid from the air.

Experiment 26. — Preparation of KOH. Dissolve 5 grams potas-
sium carbonate, K2CO3, in an evaporating dish containing 15 cc. of
water. Add a mixture of 3 grams Ba(0H)2
and 10 cc. of water. Heat on the sand-bath
for five minutes. Filter off the solution. Ob-
serve the precipitate. Evaporate some of the
solution to dryness in the evaporator.

Questions. ( i ) Write the reaction which takes
place between K2CO3 and Ba(0H)2. (2) What
is the insoluble white material left on the filter-
paper? (3) Is the KOH soluble or insoluble?
(•4) What other material could be used in place
C of Ba(0H)2? (5) If NajCOs were used instead
Fig. 54. —Preparation of KjCOj, what product would be formed ? Write
of KOH. ^j^g reaction. (6) What reaction does K2CO3

give with litmus paper? (7) What reaction does NaOH give?
(8) What are some of the uses made of KOH? (9) What would
result if the KOH in the evaporator were left exposed to the air
for a day or so ?

154. Potassium Nitrate. — This salt is found in small
amounts in fertile soils where conditions have been favor-
able for nitrification processes (see Section 92). It is
extensively used in the arts, and is prepared from
sodium nitrate deposits which occur as natural products
known as Chile saltpeter. It is an oxidizing agent and
is one of the ingredients of gunpowder which is a mix-
ture of sulfur, carbon and potassium nitrate. Potas-
sium nitrate, in small amounts, is occasionally used for
the preservation of meats.

POTASSIUM, SODIUM, ETC. I29

155- Potassium Carbonate. — When wood ashes are
leached, potassium carbonate is the chief alkaline salt
extracted, and this product is called potash which, by
the removal of impurities, furnishes pure K.CO^. Potas-
sium carbonate is prepared from the chlorid in the same
way that sodium carbonate is prepared from its chlorid as
explained in Section 162.

156. Potassium Chlorate is prepared by the action of
chlorin gas upon potassium hydrate. It is used in the
laboratory as an oxidizing agent, and for the preparation
of oxygen. It is one of the ingredients of safety matches.

157. Potassium Sulfate is found in nature in the form
of double salts, in the Stassfurt deposits and elsewhere.
It is employed in the preparation of alum and other com-
pounds. There are two sulfates of potassium : primary on
acid potassium sulfate, KHSO^, and secondary or normal
potassium sulfate, K^SO^.

158. Miscellaneous Potassium Salts. — Potassium
forms a large number of salts, as KCl, KBr, KF, KI,
KCN, Kfi, KjS, KNOa, many of which are very valuable
in medicine, in the arts as photography, and in the labora-
tory for the preparation of other compounds. The salts
of potassium vary in chemical and physical properties
according to the acid elements or radicals with which the
potassium is combined. All of the common salts of
potassium, except the double silicates, are soluble in
water.

159. Occurrence of Sodium. — Sodium and potassium
are very much alike in general properties, and form analo-

I3O AGRICULTURAL CHEJMISTRY

gous salts and compounds. Sodium is not as strong a
type of basic element as is potassium and can be sepa-
rated from its compounds more readily, although it is not
easily replaced by other elements or by simple chemical
forces. Sodium and its compounds are less expensive
than potassium and its compounds. In industrial opera-
tions, sodium salts are more extensively used, but to the
agricultural student, potassium is of greater importance
because sodium takes little or no part in plant nutrition.
In animal life, however, sodium chlorid plays an import-
ant r61e. Sodium is never found in nature in a free state,
sodium chlorid being one of the most abundant of its
salts. Sodium is also found as silicates and in small
amounts in other forms.

160. Sodium Chlorid. — Extensive deposits of this salt
are found in nature ; in some places it is mined, the prod-
uct being known as rock salt. It is present in sea-water
in large amounts from which it is occasionally obtained
in an impure form along with a large number of other
salts. When pure, sodium chlorid forms colorless, trans-
parent cubes. A large amount of commercial salt is ob-
tained by the evaporation of water from salt springs. In
some localities, water is forced into and through deposits
of salt which it dissolves and is then pumped out and
evaporated to dryness. Sodium chlorid is extensively
used for the preparation of sodium and other compounds
as hydrochloric acid. It is not found to any appreciable
extent in ordinary agricultural plants, but in some alkali
plants there are quite large amounts. When sodium
chlorid contains impurities, as calcilim chlorid and lime

POTASSIUM, SODIUM, ETC. I3I

salts, the material readily absorbs moisture from the air
while other compounds cause it to form lumps and hard
cakes. Hence a salt which readily absorbs moisture or
forms hard lumps is not a pure one. Sodium chlorid
takes but little or no part in plant life but is necessary
for animal life.

161. Sodium Nitrate. — Extensive deposits of sodium
nitrate are found in Peru, Chile, and other South Ameri-
can countries. It is commonly called Chile saltpeter.
As stated in Section 154, it is extensively used for the
preparation of potassium nitrate and in the manufacture
of nitric acid and commercial fertilizers. Sodium nitrate
is commercially and agriculturally an important product.
The value of nitrogen in fertilizers is usually based upon
its selling price. Small amounts of this salt formed by
the process of nitrification are found in soils of high fer-
tility. Because of its solubility, however, sodium nitrate
never accumulates in soils.

162. Sodium Carbonate. — Commercially, this salt is
known as soda and is one of the most useful chemicals
manufactured. It is extensively used in the making O'f
soap and glass, and in other commercial operations. It
is prepared by two processes, one known as the L,e Blanc
process, and the other as the ammonia or Solvay process.
By the I^e Blanc process, it is prepared from sodium
chlorid treated with sulfuric acid which produces Na^SO^.

2NaCl + H,SO, = Na,SO, + 2HCI.
The sodium sulfate is heated with charcoal which pro-
duces sodium sulfid.

Na^SO, + 2C = Na^S + 2CO,.

132 AGRICULTURAL CHEMISTRY

When heated with calcium carbonate, sodium sulfid forms
sodium carbonate and calcium sulfid, the latter product
being insoluble in water while sodium carbonate is solu-
ble in water, and hence is readily separated by filtration.
The process of manufacture usually consists in mixing
coal and calcium carbonate with sodium sulfate, the prod-
uct being known as crude soda which is refined and from
which calcined and crystallized soda are obtained.

In the Solvay process, (NHj^COj is employed, which
forms, with sodium chlorid, HNaCOj which when heated
yields Na^COs, CO^ and H,0.

163. Sodium Hydroxid. — This base is prepared in the
same way as KOH ; Na^COj being used in place of
K2CO3. NaOH is extensively used in the manufacture
of soaps.

164. Sodium Phosphates. — Sodium forms three phos-
phates : primary sodium phosphate, secondary sodium
phosphate, NagHPO^, and tertiary or normal sodium phos-
phate, Na3P04. Phosphates of soda are not found to any
appreciable extent in soils because phosphoric acid forms,
with iron, alumina and calcium which are always present,
insoluble compounds.

165. niscellaneous Sodium Salts. — Like potassium,
sodium forms a large number of salts as Na^SO^, NaHSO^,
NaBr, NaCN, Na^S and Na^O. Sodium compounds are
all soluble except the silicates and a few of the more com-
plex salts.

As previously stated, salts of sodium are similar to the
corresponding salts of potassium. The sodium com-

POTASSIUM, SODIUM, ETC.

133

pounds are amoug the most useful aud important com-
pounds found in nature.

Experiment 2j. — Fill a cylinder about two-thirds full of water,
and place upon the surface of the water a piece of Na about half as
large as a pea, using forceps for the
purpose. If there is no small piece
of Na in the bottle, one may be cut
by means of a knife without re-
moving the Na from the naphtha
which surrounds it. Observe the
result when the Na is placed upon
the water. The apparatus can be
arranged and the escaping hydro-
gen collected as shown in Fig. 55.
(The test-tube should be filled with
water and the Na wrapped in a
piece of filter- paper. )

Questions, (i) Give the reaction
which takes place between the Na
and the H2O. ( 2 ) "What gas is lib-
erated? (3) What becomes of the
Na in the experiment? (4) Is this
product soluble or insoluble? (5)
Test the liquid in the cylinder with
litmus paper and observe the result.
(6) Is Na a light or heavy metal ?1^^
Why? (7) Is it active or inert? (8)
Why is Na always kept in a bottle
containing naphtha or kerosene ? (9) Since Na is found in nature
and its compounds are present largely in sea-water, why does not
this element, Na, decompose sea-water as it did the water in this
experiment.

Fig- 55- — Decomposition of water
by the use of sodium.

CHAPTER XIX
Calcium, Magnesium, and Their Compounds
i66. Occurrence of Calcium. — This element is found
widely distributed in nature in the form of calcium car-
bonate, CaCOg, calcium phosphate, Ca^i^FOJ.^, and calcium
sulfate, CaSO^, and is a 5^ellowish metal which readily
oxidizes and decomposes water. It enters into the com-
position of both plant and animal bodies and takes an
important part in life processes. Its compounds are use-
ful in the industries, lime, cement, and mortar being some
of the forms in which it is employed. Calcium is not
easily separated from its compounds.

167. Calcium Carbonate. — This compound, in the form

of limestone
and marble, is
found quite
extensively.
It is soluble to
a slight ex-
tent in water
charged with
carbon dioxid,
and hence
many waters,
as stated in

Fig. 56. Section of lime kiln. ScctlOU 65,

owe their hardness to its presence. Calcium carbonate is
used principally for the preparation of quicklime, in the

CALCIUM, MAGNESIUM, ETC.

135

manufacture of glass and in the refining of some of the
metals where it is employed as a flux.

168. Calcium Oxid. — When calcium carbonate is sub-
jected to heat, as in lime kilns or specially constructed
furnaces, the carbon dioxid is separated and the oxid ob-
tained. Layers of limestone and wood are placed alter-
nately in the lime kiln, as shown in Fig. 56; the combus-
tion of the wood furnishes the necessary heat for the de-
composition of the carbonate. Calcium oxid or quick-
lime readily combines with both the carbon dioxid and
moisture of the air, forming air-slaked lime. During this
process of slaking, there is a material increase in volume
often resulting in the bursting of the barrels in which the
lime is stored. Calcium oxid is used for the preparation
of calcium hydroxid and mortar.

169. Calcium Hydroxid. — When water is added to cal-
cium oxid or quicklime, the material
undergoes the slaking process and cal-
cium hydroxid, CaCOH)^, is produced.

CaO + H,0 = Ca(OH),.
Calcium hydroxid or slaked lime
readily absorbs carbon dioxid from / -.i-j^^-Q
the air and forms calcium carbonate. ^1
Ca(0H)2 is somewhat soluble in \\^
water, forming what is commonly /
called lime water. When carbon
dioxid is passed into lime water, the
solution becomes turbid, due to the Fig. 57.

formation of CaCO,. This reaction furnishes a means

136

AGRICULTURAI, CHEMISTRY

of testing for carbon dioxid. If a small amount of
any material supposed to contain carbonates is placed
in a test-tube along with a little water, and then a small
glass tube or loop-tube containing a few drops of lime
water is inserted in the test-tube, after the gas is liberated
by hydrochloric acid, the drop of lime water becomes
turbid, due to the formation of CaC03 (see Fig. 57).

170. Calcium Sulfate. — Deposits of this salt known as
gypsum, CaS04.2H20, are found abundantly in some lo-
calities. Gypsum or land plaster is used as a fertilizer
and also for the preparation of plaster of Paris. The
"setting" of plaster of Paris is due to the fact that when
the water of crystallization is expelled, the substance is
again capable of taking up water, expanding, and form-
ing a hard mass.

171. Calcium Chlorid. — This salt is not found in nature
to any appreciable extent. It is employed in the labora-
tory in desiccators and for the drying of gases.

172. Bleaching=Powder. — This mate-
rial is made by passing chlorin into a
solution of lime water. The chlorin is
held in chemical combination, forming
calcium hypochlorite, Ca(C10)2, which
readily gives up its chlorin and is exten-
sively used for bleaching and disinfect-
ing purposes as explained in Section 89.

173. Calcium Phosphate. — Deposits
Fig. 58. Apatite rock, of this material are found in nature in
various physical forms as soft phosphate, and in crystalline

CALCIUM, MAGNESIUM, ETC. 137

form, as apatite rock, see Fig. 58. Calcium phosphate is
extensively used for the preparation of commercial fer-
tilizers as explained in Section 109.

174. Mortar. — When quicklime is slaked and mixed
with sand, it forms at first a mechanical mixture. When
it is placed upon the walls of buildings, a chemical change,
known as the hardening or setting process, takes place.
When this change occurs, the moisture is expelled and
the carbon dioxid of the air changes the calcium hydroxid
to calcium carbonate. In the slaking of lime and setting
of mortar, the following reactions take place :
(i) CaO +H,0 = Ca(OH),.
(2) Ca(0H), + C0,:=CaC03.
When magnesium carbonate and aluminum silicate are
present, forming a part of the composition of the original
lime rock, hydraulic cement is produced which has the
property of setting under water.

Experiment 28. — Testing quality of lime. Place about 40
grams of lime, CaO, in an evaporating dish and moisten with water
warmed to about 35° C. Note the reaction. Good lime readily
undergoes the slaking process. Place some of the slaked lime in
a bottle, add about 100 cc. of distilled water, shake vigorously and
leave the lime in contact with the water for four hours or longer,
then filter some of the solution of lime water, and test it by
forcing respired air through it as explained in Experiment 24.

Place about one-half gram of the slaked lime in a test-tube, add
10 cc. of water and then a few drops of HCl. When action ceases,
add more HCl, a little at a time, and heat. The material which
fails to dissolve usually consists of insoluble silica and clay. Lime
of a high degree of purity contains less than 10 per cent, of acid-in-
soluble impurities.

Questions, (i) Was any heat evolved when the lime was

138 AGRICULTURAL CHEMISTRY

slaked? Why? (2) Did any noticeable change take place in vol-
ume during slaking ? (3) What is lime water? (4) What is the
object of forcing respired air through the lime water of the test-
tube? (5) Write the reaction which took place. (6) Write the
reaction when HCl was added to Ca(0H)2.

175. Glass. — Glass is a double silicate of calcium and
sodium, produced by fusing pure sand, sodium carbonate
and lime. When potassium carbonate is substituted for
the sodium salt, Bohemian or hard glass is prepared.
Other kinds and varieties of glass are made by intro-
ducing other substances and giving different mechanical
treatment to the material during its preparation.

i76. Occurrence of Magnesia. — This element does not
occur as extensively in nature as calcium which it resem-
bles in many respects. It is found associated mainly
with calcium in the mineral dolomite, a double carbonate
of calcium and magnesium. Magnesium is separated
from its compounds more readily than calcium. It is
found in both plant and animal substances as is calcium.
In some plants and in some parts of the plant, as in the
seeds of grains, it is found more abundantly than calcium.
It is generally considered one of the essential elements of
plant food. The compounds of magnesium resemble
those of calcium in many respects, but differ materially
from the calcium salts in both chemical and physical
properties.

177. riagnesium Salts. — Magnesium carbonate and
magnesium sulfate (Epsom's salt) are among the most
common of the magnesium compounds. Magnesium
chlorid, MgCl^, and MgSO^ are found as double salts in

CALCIUM, MAGNESIUM, ETC. I39

the Stassfurt deposits. Magnesium oxid is obtained by
the combustion of magnesium. Magnesium also forms
other compounds as nitrates, phosphates, silicates, etc.

Experiment 2g. — Hold a piece of magnesium ribbon about an
inch long in the forceps and apply a lighted match to the ribbon.
Examine the product.

Questions, (i) What are some of the chemical properties of
the element as observed from this experiment ? (2) What product
was formed? Write the reaction. (3) Which would weigh more,
the original magnesium ribbon or the white powder obtained from
its combustion ? Why? (4) Why does magnesium produce such
an intense light ?

CHAPTER XX
Iron, Aluminum, and Their Compounds

178. Occurrence of Iron. — Iron is found in nature
mainly in the form of its oxids, hematite, FejOg, and
magnetite, FegO^. It also occurs in the form of carbonate,
FeCOg, pyrite, FeS^, and brown iron ore or basic hydroxid.
It is found in the soil in combination with silicon and
other elements, forming double silicates. It enters into
the composition of all plant and animal bodies and takes
an essential part in plant growth and animal life. Some
waters contain carbonate of iron which, like calcium
carbonate, is soluble in the presence of carbon dioxid ;
upon exposure to the air, the iron is precipitated as hy-
droxid, forming a brown deposit. Iron takes an im-
portant part in industrial operations and its chemistry
has been more extensively studied than that of any other
element.

179. Reduction of Iron Ores. — Only iron ores of a high
degree of purity are ready, as mined, for the blast-furnace.
Magnetic iron ore is concentrated and separated from its
impurities by magnetic concentrators. The blast-fur-
nace used for the production of cast iron is constructed
of brick and is shown in Fig. 59. Ore, coke, and flux,
usually limestone, are mixed in the right proportion and
introduced into the top of the furnace. The flux is used
to separate the impurities, forming a fusible slag which
is largely calcium silicate. Hot air is forced into the
furnace by means of blowing engines, through tuyeres.

IRON, ALUMINUM, ETC.

141

Fig. 59. Blast-furnace (after Hart).

142 AGRICULTURAL CHEMISTRY

The carbon dioxid produced first is reduced to carbon
monoxid which passes over the heated ore in the upper
part of the furnace, and is the main reducing agent of the
blast-furnace. The carbon monoxid given off at the top
of the furnace is collected and used for heating the blast.
The furnace is constructed so as to utilize the heat to the
best advantage and so that the blast can act efficiently.
The slag which carries a large portion of the impurities
of the ore, being lighter than the molten iron, collects on
the surface and is removed from time to time. The
molten iron is run off from the bottom of the furnace
into molds ; iron that is produced in this way is known
as pig iron. It contains a number of impurities as phos-
phorus, carbon, silicon and sulfur.

i8o. Wrought Iron, — Wrought iron is produced from
cast iron by two ' processes : ( i ) the puddling process
which consists of oxidizing the impurities by means of a
blast of hot air which is passed over or blown through
the iron, this is known as the Bessemer process ;
and (2) the cementation process by which the cast
iron is mixed with iron ores reasonably pure and heated
to a high temperature so that the oxygen of the ores may
oxidize the carbon, phosphorus and sulfur of the cast
iron. Wrought iron is the purest commercial form of
iron. It usually contains about 0.5 per cent, of carbon,
and melts at about 2000° C. The nature of the
impurities determines the character of both wrought iron
and steel, as any increase in the amount of carbon de-
creases its malleability and other desirable properties.
181. Steel. — This form of iron contains less carbon

IRON, ALUMINUM, ETC.

143

144 AGRICULTURAL CHEMISTRY

than cast iron, but more than wrought iron. It is pre-
pared by oxidizing the impurities of iron by means of a
blast of hot air. This is accomplished by heating the
cast iron in converters and then forcing through it a blast
of hot air which oxidizes the larger portion of the im-
purities. By adding cast iron, steel containing almost
any desired amount of carbon can be obtained. Iron and
steel wire are made by drawing rods through hardened
steel plates, the material being properly tempered during
the operation. The thin coat of oxid formed on the sur-
face is removed by dipping the wire into a bath of dilute
sulfuric acid.

182. Rusting of Iron. — Iron in all" of its forms readily
undergoes oxidation and rusting, due to the joint action
of oxygen and water which results in the production of
a basic oxid of iron. When the surface of iron is pro-
tected, as by painting, oxidation and rusting are pre-
vented. When iron is heated to its kindling temperature,
it readily oxidizes as in Experiment i. In the wielding
of iron, oxidation is prevented as far as possible by ma-
nipulation and occasionally by the use of materials, as
borax, to remove the thin coating of oxid. Iron is read-
ily acted upon by all acids, forming a large number of
salts.

183. Iron Compounds. — Iron forms two series of salts :
ferrous and ferric. Ferrous sulfate, FeSO^, commonly
called copperas, is used most extensively of any of the
iron salts especially for the dyeing of cloth, and to some
extent as a disinfectant.

Experiment ^o. — Dissolve 0.5 gram of ferrous sulfate in 20 cc. of

IRON, ALUMINUM, ETC. I45

water. Filter if the solution is not clear, and divide the filtrate
into two portions. To the first portion, add a few drops of ammo-
nium hydroxid until a precipitate is obtained. To the second portion,
add about 5 drops of strong nitric acid. Heat to boiling ; when
cool, add ammonia to neutralize the acid and precipitate the iron.
The nitric acid oxidizes the iron and changes it from the ferrous
to the ferric condition. Compare the two precipitates.

Questions, (i) What was formed when NH^OH was added to
FeSO^? Write the reaction. (2) Give the color and other physical
properties. (3) What change did the HNO3 produce ? (4) What
change did you observe in the color of the solution during the
boiling? (5) What was produced when NH4OH was added to
Fe(0H)3? Write the reaction. (6) Give the color and some of
the physical properties. (7) How does this last precipitate differ
from the first one obtained?

Experiment ji. — Dissolve i gram tannic acid in 25 cc. of hot
water. Dip a piece of cotton cloth into this solution. Dry the
cloth and then dip it into a solution of ferrous sulfate (i gram per
25 cc. of water). After the cloth has dried, see if the color can be
removed by washing. Add 5 cc. of ferrous sulfate solution to 5 cc.
of tannic acid solution. Observe the result. The FeSO^ forms,
with the tannic acid, iron tannate.

Questions, (i) Would the FeSO^ alone give the same color
to the cloth? Why? (2) Was the color produced a permanent
one? (3) Tea contains tannic acid ; why does tea prepared in an
iron kettle give a black infusion ? (4) What was produced when
the solution of FeSO^ was added to the tannic acid ?

184. Occurrence of Aluminum. — Aluminum is a gray-
ish white metal much lighter than iron and of greater
tensile strength and is found mainly as one of the constitu-
ents of clay that is formed from the disintegration of
feldspar, a double silicate of potassium and aluminum.
It is also found in other combinations, as in mica and
cryolite, and is present in nearly all soils and in small

146 AGRICULTURAL CHEMISTRY

amounts is found in plant substances although it takes no
part as plant food. Aluminum is not easily isolated from
its compounds. It can be produced bj' treatment of its
chlorid with sodium but is now quite extensively pre-
pared by electrolysis. When pure, it is not as readily
oxidized or acted upon by acids as is iron. Aluminum
forms a large number of compounds and also alloys with
many of the metals.

185. Alums. — In industrial operations, alum is used
the most extensively of any of the compounds of alumi-
num. An alum is a double sulfate of aluminum. It has
the general composition of MAl(SOj2i2H20 in which M
represents any bivalent metal as potassium. The Al can
also be replaced by a trivalent element. Alum is exten-
sively used in the tanning of leather, manufacture of
paper, and in the coloring of cloth as the basis of the
mordant or material for making the dye permanent.
Alum is also used occasionally in the preparation of
baking-powders.

Experiment 32. — Add a few drops of alum solution to a test-tube
containing 5 cc. of water, and then add a few drops of tincture of
logwood and 2 cc. (NH4)2C03. Observe the result. Mix about
2 grams of flour in a dish with water containing a few drops of
alum. Add a few drops of logwood and the same amount of am-
monium carbonate solution ; mix well, and observe the result. Re-
peat the test, using a bakipg-powder, and test for the presence or
absence of alum. In the presence of alum, a blue color is always
obtained with tincture of logwood and ammonium carbonate solu-
tion.

Experiment 3^. — To a solution of ^^^ albumin, add a few drops
of alum solution and observe the result.

IRON, ALUMINUM, ETC. I47

Questions, (i) Does the alum cause a precipitate ? (2) Of what
is the precipitate composed ? (3) How would alum act in the di-
gestive tract in the presence of soluble albuminous compounds?
(4) Why is alum an undesirable ingredient in baking-powders and
foods.

186. Pottery. — Pure clay or kaolin is used for the
manufacture of the best grades of porcelain and pottery.
The plastic clay is modeled into the desired form and
then dipped into a bath containing feldspar and other
materials which, when fused, form the glaze. Ordinary
earthenware is made from impure clay which contains
compounds of iron and other elements. Brick and tile
are also made from clay, the physical properties, as color,
hardness, weathering properties, etc., depending upon
the amounts of iron, lime, magnesia, and alkalies present.
As ordinarily found in the soil, clay is mechanically asso-
ciated with a large number of other substances, many of
which contain the elements essential to plant life as po-
tassium and calcium. Pure clay itself contains no plant
food, but clay soils are usually among the most fertile
because, along with the disintegration of feldspar and
other rocks, various minerals that impart fertility are
made available and are associated with the clay.

CHAPTER XXI

Copper, Zinc, Lead, Tin, Arsenic, Mercury, and

Their Compounds and Alloys.

187. Commercial Importance. — The compounds of
copper, ziuc, lead, tin, and arsenic, while they do not
enter into the composition of either plant or animal
bodies, are of value in agriculture because of their pres-
ence in many useful materials.

188. Occurrence of Copper and Its fletallurgy. — This
element is found in the free state and also in combination
with oxygen as CuO and CU2O, with sulfur as CUjS, and
with iron and sulfur as copper pyrite, CUjS.FcjSj. The
ores of copper are first roasted, and if iron is present in
large amounts, it is removed as a silicate. The "matte,"
as it is called, thus produced is subjected to further re-
fining. Copper is also produced by electrolysis.

189. Copper Sulfate. — This salt is used the most ex
tensively of any of the copper compounds and is produced
by the action of sulfuric acid upon either metallic copper
or its sulfid. It crystallizes with 5 molecules of water of
crystallization. It is commonly called blue vitriol, and
is extensively used in the preparation of pigments, for the
preservation of wood, for copper-plating and for the
treatment of fungus diseases in plants as in the Bordeaux
mixture where it is the principal ingredient.

Experiment j4. — Dissolve 6.2 grams of copper sulfate and 3.50
grams of sodium potassium tartrate in 100 cc. of water. Dissolve
a small amount of glucose (o. i gram ) in 5 cc. of water, add 5 cc.

COPPER, ZINC, LEAD, ETC. 149

of alkaline copper sulfate solution and heat to boiling. Observe
the brown precipitate of Cu.,0. The amount of Cu.^O produced is
proportional to the amount of glucose present and when the work
is carefully done and the copper weighed or determined by other
means, the percentage amount of glucose in a material can be de-
termined. A hot alkaline solution of copper sulfate is reduced to
CU2O in the presence of glucose, and a few other organic com-
pounds.

190. Bordeaux Mixture. — In this preparation, the
copper is present as an insoluble hydroxid. To prepare
the Bordeaux mixture 12.5 pounds of copper sulfate
are dissolved in about 2 gallons of ho-t water ; 3.5 pounds
of lime are slaked in about 2 gallons of water, and
strained into a barrel through a coarse cloth to remove
any large pieces. The solution of copper sulfate is then
poured into the barrel and well stirred. The reaction
which takes place is

Ca(OH), + CuSO, = Cu(0H)3 + CaSO,.
In the preparation of Bordeaux mixture, it is the aim
to use just a sufficient amount of lime to combine with
all of the copper.

191. Occurrence of Zinc. — This metal is found in nature
mainly as zinc carbonate, ZnCOg, and to a less extent as
the sulfid. Small amounts are found in other forms.
Zinc is separated from its ores by roasting with char-
coal which, volatilizes and it is then collected as zinc
dust. It is then purified and prepared for various pur-
poses.

192. Compounds of Zinc. — Zinc forms a large number
of compounds as ZnCl^, Zn(OH),, ZnS, and ZnSO,.

150 AGRICULTURAL CHEMISTRY

Some of the zinc salts are used in the preparation of
paints, while the metal itself is used in many ways as in
the preparation of alloys, solder, and galvanized iron.

193. Galvanized Iron. — Iron is galvanized by being cov-
ered with a layer of zinc. Galvanized iron is extensively
used for water pipes because it does not rust so readily as
ordinary iron. When heated, however, the zinc coating
of the galvanized iron is removed.

194. .Occurrence of Tin.— Tin is found in nature largely
in the form of the oxid. SnO,, and, to a less extent, in
combination with other metals. The oxid is heated in a
furnace with charcoal, and the molten tin cast into bars.

195. Tin Salts. — Tin forms two series of salts, stan-
nous and stannic. In the former, the element is bivalent,
and in the latter, it is tetravalent. Stannous and stannic
chlorid, the sulfid, oxid and hydroxid are among the
more common tin salts. They are used in the arts in
various ways as pigments and as mordants in the coloring
of cloth. Tin forms a number of alloys and is extensively
used for roofing and other purposes. Ordinary tinware
is simply iron-coated with a layer of tin.

196. Occurrence of Lead. — Lead is found principally
in the form of sulfid (galena). It is also found in combi-
nation with silver and other metals, and, in the process
of refining of silver, is separated as a by-product.

197. Oxids of Lead — There are four oxids of lead,
namely : lead monoxid, PbO, lead peroxid, Pb02, lead
suboxid, Pb^O, and lead sesquioxid, Pb^O,. The sub-

COPPER, ZINC, LEAD, ETC. 15I

oxid, PbjO, is produced when lead is exposed to the air;
in a pure condition, it is a black powder. Lead oxid,
PbO, is a yellow powder which, if heated, produces
litharge, a yellowish red material. This substance is ob-
tained largely in the separation of lead from silver. Lead
peroxid, PbOj, is an oxidizing agent, and in some respects
resembles manganese dioxid. Red led or minium, Pb^O^,
is produced by heating lead oxid, and is used as a pig-
ment.

198. Lead Carbonates. — The normal carbonate, PbCOj,
is occasionally found in nature. The basic carbonate,
Pb(OH)3.3PbC03, is common white lead, which is exten-
sively used as a pigment. It is produced by different
methods from litharge and other compounds of lead, as
well as by treatment of the metal itself.

199. Lead Salts. — Lead nitrate, Pb(N03)2, is produced
by the action of nitric acid on lead ; and lead sulfate, by
the action of a sulfate upon a soluble lead salt. Lead
chlorid, PbCl^, is precipitated whenever a chlorid or hy-
drochloric acid is added to a solution containing a lead
salt. The salts of lead are more insoluble than those of
many other metals.

200. Uses of Lead. — Lead is used for making water
pipes, for lining tanks, particularly those in which sul-
furic acid is stored, in the preparation of solder, and in
many alloys. Lead is insoluble in most waters although
the salts and organic matter in some waters may cause a
sufficient amount to dissolve to render the use of lead
pipes objectionable from a sanitary point of view.

152 AGRICULTURAL CHEMISTRY

201. Occurrence of Arsenic. — This element occurs in
the free state to a limited extent, but usually in combina-
tion with other elements, as oxygen, iron, and sulfur.
In some of its properties, arsenic resembles phosphorus,
and forms similar compounds, although arsenic has
weaker acid properties than phosphorus. It forms a large
number of compounds, among which are the arsenates,
and arsenites which are salts of arsenic and arsenious
acids. In the presence of a strong base element, arsenic
deports itself as an acid while, in the presence of a strong
acid element, it exhibits basic properties. Other ele-
ments, particularly antimony and bismuth, and to a less
extent aluminum, have this same property of acting both
as an acid- and base-forming element. Some of the com-
pounds of arsenic are extensively used as pigments and
insecticides.

202. Paris Green. — Pare Paris green is an aceto-arse-
nite of copper and has the following composition : Cop-
per oxid, 31.29 per cent., arsenious oxid, 58.65 per cent.,
acetic acid, 10.06 per cent. Some of the commercial
grades of Paris green contain soluble forms of arsenic,
while others are adulterated with lime and insoluble sili-
cates. The arsenic should be insoluble and have
no injurious effect upon vegetation. In case soluble
arsenic is present, the foliage is destroyed. Pure Paris
green should completely dissolve in hydrochloric acid.
In case silica is present, an insoluble residue appears
when the material is treated with hydrochloric acid,
lyondon purple and various arsenates and arsenites are
occasionally used for insecticides. lyOndon purple con-

COPPER, ZINC, LEAD, ETC.

153

tains soluble arsenic. In case of accidental poisoning
with Paris green, hydroxid of iron is usually employed
as an antidote.

203. Occurrence of flercury. — Mercury is found in
nature mainly in the form of the sulfid, HgS, commonly
called vermilion which, when roasted, yields SOj and Hg.
Mercury is extensively used in the preparation of alloys
and amalgams.

204. Compounds of Hercury. — I^ike copper, tin and
many other elements, mercury forms two series of salts,
the mercurous and mercuric compounds. Mercurous and
mercuric oxids, Hg^O and HgO, mercurous and mercuric
chlorids, HgCl and HgCl.^, and the nitrates and sulfids
are among the more important compounds of mercury.
Mercuric chlorid is employed as an insecticide and also
as a germicide. It is very poisonous and is very destruc-
tive to all forms of animal and plant life ; it is frequently
used for the treatment of fungus diseases of plants.

Experiment 55. — Replacement of metals. Place, in separate
test-tubes, ( i) 5 cc. of silver nitrate, (2) a piece of copper, and (3)
5 cc. of lead nitrate. To
the first test-tube, add a
piece of copper foil, to the
second a small piece of
lead, and to the third,
a piece of zinc. After
a few minutes, examine
the contents of the vari-
ous test-tubes and observe
the results. Copper has
the power of replacing silver in solution, lead has the power of re-
placing copper, and zinc has the power of replacing lead.

Mt t PKOtUG*

<»0.J 8 PRODUCT

u

Fig. 61.

U

154 AGRICULTURAI, CHEMISTRY

The more electro-positive elements replace those which are less
electro-positive. Observe in these experiments that the copper is
coated with silver, the lead with copper, and the zinc with lead.
Write the following reactions which have taken place :
(i) AgN03-fCu =

(2) Cu(N03)2 + Pb =

(3) PbCNOs)^ + Zn =

Questions, (i) Which element is the most positive? (2) What
elements can zinc replace ? (3) Why does copper replace silver?
(4) Why does lead replace copper? (5) What does this experi-
ment show as to the relative properties of the three elements, cop-
per, silver and lead ?

CHAPTER XXII
Water Content and Ash of Plants
205. Water. — Water is present in all food materials,
and in many cases makes up a very large portion of the
weight of a substance. In vegetables, in milk, and in
the juices of meat, water is present to such an extent as
to be perceptible to the senses. Substances like flour,
meal and starch, which appear perfectly dry, are not free

Fig. 62. — Water-oven.

from water, but contain from 9 to 12 per cent. This
hydroscopic water, as it is called, is held mechanically by
the particles of which the material is composed, and the

156

AGRICULTURAL CHEMISTRY

amount thus held depends upon the extent of the pre-
vious drying of the material and the hj-droscopic condi-
tion of the air. Inasmuch as air always contains some

Fig. 63. Analytical balance.

water, it necessaril}' follows that all substances exposed
to the air must likewise contain some water.

In order to remove the last traces of water from a sub-
stance, it is dried in either a water- or a hot-air oven at a

WATER CONTENT AND ASH OF PLANTS 1 57

temperature of 100° C, — the boiling-point of water. This
converts all of the water in the material into steam,
which is then expelled. A water-oven, shown in Fig.
62, has double walls, the space between the walls being
partially filled with water, which is kept boiling by means
of a gas burner placed below the oven. The substance is
weighed in a suitable dish and then dried in the water-
oven until the weight is reasonably constant, the loss of
weight being considered water.

The determination of water in foods, although appar-
ently simple, is a difiicult and troublesome chemical pro-
cess because many foods, when heated to 100° C, suffer
changes, and give off volatile organic compounds along
with the water ; or the organic matter may undergo a
change in composition, as oxidation. For determining
the absolute moisture content of foods, the chemist em-
ploys a drying bath of different pattern from that shown,
and the material is dried in a current of some neutral gas,
as hydrogen, to prevent oxidation of the
substance. All of the dishes in which
the substances are placed, during anal-
ysis, are dried and cooled in desiccators
out of contact with air, so as to remove
all traces of hydroscopic moisture. The
weighings are made on analytical bal- Fig. 64. Desiccator,
ances which are scales of extreme accuracy (see Fig. 63).
The determination of water is one of the most difficult
parts of the analysis of plant or animal substances.

206. Dry flatter. — The dry matter of a material is the
portion which is left after all the water has been re-

158

AGRICULTURAL CHEMISTRY

moved. Dry matter, as the term implies, is the dr>^ ma-
terial free from all traces of h3'droscopic moisture, and
the amount is determined by subtracting the per cent, of
water from loo. For example, if flour contains 1 2 per cent,
water there will be 88 per cent, of dry matter. The amount
of dry matter in substances ranges between wide limits as 7
per cent, and less in some fruits to 99 per cent, in sugar.
Experiment 36. — Determination of water in potato. Carefully
weigh an aluminum dish (Fig. 65). Cut
thin slices from different parts of a
potato and reduce them to i/8-inch
cubes. Weigh in the dish, some of
these pieces, forming a layer not more
than two deep. Record the weight,
place in the dish a small piece of paper with your initials,
then set the dish in the water-oven
(Fig. 62), and allow it to remain
twenty-four hours, or until the next
exercise. After drying, weigh again,
and from the loss of weight calculate
the per cent, of water in the potato.
(Weight of potato and dish before drj'-
ing, minus weight of potato and dish
after dr)'ing, equals weight of water
lost. Weight of water divided by weight
of potato taken, multiplied by 100,
equals the per cent, of water in the
potato. )

Experiment j/. — Water in flour.
In the same manner, determine the
per cent, of water in flour, using about
Fig- 66. 2 grams of flour, and noting the ex-

act weight before and after drying.

Experiment jS. — Water in milk. Weigh a watch-glass and place
it on the water-bath (see Fig. 66). Measure with a pipette 3 cc. of
milk into the watch-glass. Evaporate to dr3-ness on the water-bath,

WATER CONTENT AND ASH OF PLANTS 1 59

completing the process in the water-oven. When dry, weigh, and
from the loss of weight, calculate the per cent, of solids. Sp. gr. of
milk, 1.032. I cc. H^O = i gram, i cc. milk = 1.032 grams. If
skim milk is used, the sp. gr. is 1.035.

Experiment J-). — Water in clover. "Weigh an aluminum dish.
Take three or four large clover plants and cut fine with shears or
knife. Weigh a portion in the dish ; dry, and weigh again as in
Experiment 36. Determine the per cent, of water in clover.

Questions, (i) How did the potato, after drying, compare in
appearance and volume with the material before drying? (2) How
does the percentage amount of water which you have obtained,
compare with the figures given in the tables of analysis. (3) In
the determination of water in milk, what was the appearance of the
milk solids? (4) What classes of compounds are present in milk
solids. (5) How does the amount of water obtained in Experi-
ment 37 compare with the amount given in the tables of analysis?
(6) What would be the shrinkage in weight of a barrel of flour if
2 per cent, of moisture were removed, and what w^ould be the in-
crease in weight if 2 per cent, of moisture were absorbed from the
air ? ( 7 ) How does the amount of water obtained in Experiment 39
compare with that obtained from the other materials? (8) How
much water is present in a ton of green clover?

207. Plant Ash. — The ash of a plant, or of any ma-
terial, is that portion which remains after the substance
is burned at the lowest temperature necessary for com-
plete, combustion. It is sometimes spoken of as the min-
eral or inorganic part, also as the non-volatile part, and
includes all of the materials, with the exception of water
and nitrogen, which the plant takes from the soil during
growth. The term ash as used in chemistry differs from
the term as ordinarily used in that the chemical a.sli is
pure ash, free from unburned particles of carbon, and also
contains elements, as sodium, chlorin, sulfur and phos-
phorus, traces of which are volatile at a high tempera-

i6o

AGRICULTURAL CHEMISTRY

ture.

Crude ash is obtained by burning a substance
until all of the carbon is
oxidized.

Experiment 40. — Determina-
tion of ash. Weigh to the
second decimal place in grams,
a dish given out for this experi-
ment. Then weigh into the dish
about 2 grams of dry clover or
other hay, place in the muffle
furnace, and let it remain until
there is no charred material left.
Cool on an asbestos mat. Weigh
again and determine the per
cent, of ash from the material
taken and the weight of the ash
obtained. Calculate the per
cent, of organic matter. Save
the ash for future experiments.
[The 500, 200, and 100 mg.
weights are to be recorded as
0.5, 0.2, and 0.1 gram; the 50,

Fig. 67. — MufHe furnace used for
determination of ash.

20, and 10 mg. weights as
0.05, 0.02, and o.oi gram.
If one used a lo-gram
weight, a 500-mg. weight,
and a 20-mg. weight, it
would be written 10.52
grams.]

208. Form of the
Ash Elements. —

None of the elements
present in the ash of
plants ever exist there

Fig. 68.— Weights for balance.

WATER CONTEN'T AND ASH OE PLANTS l6l

in the elementary or free state, as free sodium or free
silicon, but they are always in chemical combination,
forming salts, or are combined with the elements
which constitute the organic part of the plant. The
ash elements are never present in the form of free acids or
free bases, although, in chemical analyses, they are ex-
pressed as acid or basic oxides. Phosphorus, for exam-
ple, never exists in the plant as free phosphorus or as
phosphoric acid, but either as a phosphate or combined
with some of the elements which constitute the organic
part.

209. Amount of Ash in Plants. — While the amount
of ash in plants is fairly constant, it will be found to vary
with the stage of growth, climatic conditions, and na-
ture of the soil. In mature agricultural plants, the amount
rarely exceeds 10 per cent, of the dry weight of the ma-
terial. Clover grown in different localities is found to
contain from 6 to 8.5 per cent, ash; other crops also
show limited variations. The ash is not evenly dis-
tributed throughout all parts of a plant ; the leaves, for
example, contain a larger amount than the seed. In the
case of corn, the amount of ash in different parts is as
follows :

Per cent.

Mature plant 5.8

Roots 3.5

Leaves 8.1

Stems entire 6.6

Grain 1.4

As previously stated, the ash elements of a plant, to-
gether with the nitrogen and water, represent all of the

1 62 AGRICULTURAL CHEMISTRY

material which is taken from the soil. In loo parts of
the dry material of any crop, from 5 to lo parts are
derived from the soil while 90 to 95 parts are supplied
either directly or indirectly from atmospheric sources,

210. Importance of Ash Elements. — Plant ash is com-
posed of potassium, sodium, calcium, magnesium, iron,
phosphorus, sulfur, silicon, and chlorin compounds.
These elements, with a few others present in small
amounts, as aluminum and occasionally manganese, boron,
etc. , are the elements which make up the mineral matter
of plants. Some of the ash elements, as potassium and
phosphorus, are absolutely necessary for the life of the
plant, while others, as aluminum and silicon, are, so far
as known, unnecessary. The essential ash elements are
potassium, calcium, magnesium, iron, phosphorus and
sulfur. The non-essential elements are sodium, silicon,
chlorin, and aluminum. But in some alkali and sea
plants, sodium, chlorin, and other elements are essential
for growth.

Chemically considered, the elements found in the ash
of plants are divided into two classes :

(i) Metals or base-forming (2) Non-metals or acid-forming

elements. elements.

Potassium K Phosphorus P

Sodium Na Sulfur S

Calcium Ca Silicon Si

Magnesium Mg Chlorin CI

Iron Fe

Aluminum Al

To the above list must be added small amounts of
other elements occasionally found in the ash of plants,

WATER CONTENT AND ASH OF PI.ANTS

163

and also oxygen, which is in chemical combination with
all of the above elements.

The essential ash elements are absolutely necessary
for the normal growth and development of plants. They
take a direct part in the production of plant tissue. The
part which each ash element takes in plant growth
has been known only for a comparatively short time. At
one time, it was believed that the ash elements were
largely accidental that the plants in taking up water from
the soil could not well keep out the soluble earthy mat-
ters, but the methods of sand and water culture have
demonstrated the necessity and the functions of the
various ash elements.

211. Water Culture. — In water-culture experiments,
the seed is germinated and then the roots
are suspended in water containing small
amounts of the different ash elements. The
roots are protected from the light, and the
solution is frequently changed. In case it
is desired to learn what effect the absence
of an element has upon the growth and de-
velopment of the plant, all of the elements
are supplied in known amounts except the
one in question which is withheld alto-
gether. The development of the plant is
observed, and if it reaches maturity and
produces fertile seeds, it is concluded that

1 1 • 1 1 -r 1 • 1 P'g- 69 —Water

the element withheld is not necessary to plant culture.
growth, while on the other hand, if the plant does not de-
velop naturally, the element withheld is considered a nee-

164 AGRICULTURAL CHEMISTRY

essary one. By eliminating the ash elements in order, a
conclusion may be drawn as to the part which each separate
element takes in plant nutrition. After repeated experi-
ments with various modifications, aided by chemical and
microscopic examinations of the plant, the functions of an
element are determined. When a plant develops under
normal conditions, there is a definite part which every es-
sential element performs during growth. In fact, a plant
may be fed, and the effects of the food be observed
as accurately as in the case of the feeding of men or
animals.

212. Sand Culture is essentially the same in principle
as water culture. Pure sand (SiOj) is treated with strong
acids, washed with distilled water, and ignited. When
properly prepared, this leaves a perfectly sterile medium
to which is added, as desired, known amounts of the
various ash elements.

Occurrence and Function of Ash Elements

213. Potassium. — Potassium is one of the most im-
portant and least variable of all the elements found in
the ash of plants. It is quite evenly distributed through-
out the growing plant and generally occurs in the entire
plant in the largest proportion of any of the essential ash
elements. It is taken up in the early stages of plant
growth and is always present to the greatest extent in the
active and growing parts, as in the leaves where the pro-
duction of plant tissue occurs. Potassium is one of the
elements most essential for the plant's development.

The function of potassium is apparently to aid in the

WATER CONTENT AND ASH OF PI^ANTS

165

production and transportation of the carbohydrate com-
pounds, as starch and sugar, and thus indirectly in the
formation of all organic matter. In sugar-
and starch-producing crops, as sugar-beets
and potatoes, it takes an important part in
the growth and development. Potassium
doubtless has much to do in the way of
regulating the acidity of the sap by forming
organic salts such as potassium bitartrate in
grapes. At the time of seed formation
there is a slight retrograde movement
of the potash, in some cases a small
part being returned to the soil. The
supply of available potash in the soil has
great influence upon the vigor of plant
growth. Weak and sickly plants are always
deficient in potash. Some crops require
more for growth than do others and some
experience difficulty in obtaining it. Some
plants contain such large amounts of potash
that they are called ' ' potash plants. ' '

Experiment 41. — Alkalinity of ashes. Weigh 2
grams hard wood ashes into a beaker containing 100 cc. HjO
over a sand-bath until it boils ; filter. To one-half of filtrate, add
10 drops of cochineal solution ; from the burette (see Fig. 38), add
dilute (i cc. acid, 40 cc. HjO) HCl until the solution is neutral.
The alkali in wood ashes is mainly KjCOg which is neutralized
with HCl. Write the reaction. Test both leached and unleached
ashes. Note number of cubic centimeters HCl used in each case.
What do the results indicate ?

Fig. 70.— Plants
grown with and
without potash.

Heat

314. Sodium. — This element, which resembles potas-

1 66 AGRICULTURAL CHEMISTRY

sium in its chemical deportment, is not absolutely neces-
sary for agricultural plants and does not occur in the ash
in such large amounts as potassium. Nearly all agricul-
tural plants are brought to maturity without its aid
except for the small amount in the seed. The amount,
if any, which plants require is very small, not sufficient
to take into consideration. It is supposed to be present
as an accidental ingredient, because sodium chlorid is
universally present in the soil, in water, and occasionally
traces of it are in the air ; hence plants could not very
well exclude it. Some alkali plants require and store up
large amounts of sodium compounds. Unlike potassium,
sodium is not so evenly distributed through the plant.
It has no special mov^ement, but is found mostly in the
lower parts of the plant. Seeds contain but little of it,
more being present in the straw and stems.

215. Calcium. — This element is always present in the
ash of plants. None of the higher plants can reach
maturity without a normal supply. Some, like clover,
beans, peas, and lucern, require so much for their develop-
ment that they are called " lime plants." Accumula-
tions of lime are found in many leafy plants, particularly
clover, where crystals of calcium oxalate may be
observed. In leaves, it appears to have the special func-
tion of aiding in the construction of the cell walls.
No new plant cells can be produced without the aid of
calcium.

From the culture experiments of various investigators,
the element calcium appears to take a prominent part in
the production of new tissues. Whenever it is withheld.

WATKR CONTENT AND ASH OF PLANTS 1 67

the growth of the plaut is restricted. Some plants, after
their growth has been checked by withholding calcium,
will show increased vigor within a few hours after
it is supplied. Calcium is assimilated in the early
stages of plant development. In wheat, for example,
80 per cent, is assimilated before the plant heads
out. Calcium assists in imparting hardiness to crops.
It does not accumulate in the seeds to such a great extent
as do other elements. Only about a tenth of the total
amount removed in grain crops is in the seeds, the re-
maining nine-tenths being present in the straw. Crops
grown on lime soils are usually well nourished, and are
more capable of withstanding unfavorable climatic condi-
tions as drought and early frosts than are crops not so
liberally supplied with lime.

Experiment 42. — Lime, CaO, in plant ash. Transfer the ash
from Experiment 40 to a beaker containing 5 cc. HCl and 50 cc.
H2O ; heat ten minutes, filter, and divide into two portions. Save
portion for Experiment 44. Make one portion neutral with am-
monia, NH4OH. Add 5 cc. NH4CI solution. To the solution,
add 5 cc. ammonium oxalate, (NH4)2C204 ; note the precipitate
which is calcium oxalate, CaCjO^.

Into a separate test-tube put o.i gram CaClj, add 5 cc. HjO and
a little HCl until acid ; then nearly neutralize with NH^OH and
add NH^Cl and (NH4)2C204. Compare this precipitate with that
from the clover ash. Observe, in this second test, that you
have taken a pure calcium salt, and that the same precipitate was
given as by the plant ash. Write the following reactions which
have taken place : CaCaO^ + Heat =? CaCOs + HCl =? CaClj -\-
(NHJ.C^O, =?

216. Magnesium is also an essential element. It occurs
in all plants and farm crops in somewhat smaller amounts

1 68 AGRICUI.TURAL CHEMISTRY

than calcium but in the seeds of grains it is stored up
three times more Hberally. Magnesium is assimilated
more slowly than calcium ; in fact it is assimilated, as a
rule, more slowly than any other ash element. The
plant does not require magnesium until the approach of
seed formation, although a small amount is necessary for
perfect leaf action as it enters into the chemical compo-
sition of the chlorophyl. When plants are grown with an
incomplete supply of magnesium, the seeds are frequently
sterile. In culture experiments, the absence of magne-
sium is not observed so much in the first stages of growth
as when the time of seed formation approaches when its
absence is followed by restricted development.

217. Aluminum is found in the ash of many plants, as
wheat, peas, beans, and rice, although it occurs in very
small amounts and, so far as known, is not essential for
plant growth. Most soils contain traces of soluble sili-
cates of aluminum, and hence plants cannot well be free
from it.

218. Iron in small amounts is necessary for plant growth.
It occurs in about the smallest amount of any of the ash
elements, but is always present in plants. When plants
are unable to obtain their requisite supply of iron, the
production of chlorophyl does not take place and they
fail to develop a normal green color.

The function of the iron is to assist in the formation of
chloroph5'l, the coloring-matter of plants. It is not known
whether iron enters into the chemical composition of the
chlorophyl, or is simply organically associated with it.

WATER CONTENT AND ASH OF PLANTS

169

219. Phosphorus, in the form of phosphates, is found
in all parts of plants. It is one of the essential elements
for plant growth. Its function is to aid in the produc-
tion and transportation of the proteid bodies. The phos-
phorus and nitrogen compounds are closely associated in
the work of producing proteids which can take place only
in the plant cells. The proteid compounds produced in
the leaves of plants are finally transported to the seed.
Many proteids which are insoluble in water are soluble
in the presence of phosphate compounds. The phos-
phates are essential in the early stages
of the plant's development. In the case
of wheat, 80 per cent, is assimilated in
the first fifty days, and in other crops,
the assimilation is equally rapid. The
phosphates accumulate to a greater extent
in the seeds of grains than in the leaves
and stems. From 60 to 75 per cent, of
the total phosphates is removed in the
seeds. The loss of phosphates from the
farm is one of the reasons why soils de-
cline in fertility.

Experiment 43. — Phosphoric acid in seeds.

Crush 25 kernels of wheat in a mortar. Place

the crushed wheat in a small Hessian crucible

and ignite; when cool, transfer the charred

mass to a small beaker. Add 10 cc. HNO3 and

50 cc. H.,0, and boil ten minutes. Break up the

, J " . • 1 -^i ^. . . , . Fig. 71.— Plants grown

charred particles with a stirring rod during with and without

the boiling. If the beaker shows signs of be- Phosphoric acid,
coming dry, add a little hot water. Filter. To half the filtrate,

lyo AGRICULTURAL CHEMISTRY

add 3 cc. ammonium molybdate. The yellow precipitate is am-
monium phosphomolybdate. See Experiments 17 and 18.

220. Sulfur also is an essential element of plant and
animal bodies, but occurs in plant tissue in comparatively
small amounts. It enters into the composition of albu-
min and other proteids. Sulfur is used by plants only
in the form of sulfates. The part which it takes in plant
life is to supply the sulfur for the proteid compounds
which always contain this element in chemical combi-
nation. Culture experiments have shown that in its
absence no growth results.

Experiment 44. — Sulfur as sulfates in plant ash. To the second
portion of the filtrate from Experiment 40 add 2 cc. barium chlorid
(BaClj), observe the result, and write the reaction, assuming SO3
to be in the form of KaSO^. In a second test-tube, add a few
crystals of NajSOi or KjSO^ to 10 cc. H2O containing a few drops
HCl. When dissolved add BaClj and compare with precipitate
obtained in first part of experiment (see Experiment 21).

221. Chlorin is not an essential ash element. It accu-
mulates mainly in the lower part of the plant, and its pres-
ence appears to be accidental, it having no decided func-
tions to perform. The statements made about sodium,
its occurrence, distribution, and importance apply also
to chlorin with which it is combined forming sodium
chlorid.

222. Silicon occurs in all plants. It is found in largest
amounts in the dense and older parts, as in the stalk and
straw, where there is less activity. In some of the lower
plants, as diatoms, there is so much silica that when the
organic matter is removed by burning, a skeleton of silica

WATER CONTENT AND ASH OF PI^ANTS 171

is left. It was formerly supposed that silica gave the
stems of grains and grasses their stiffness. Perfect wheat,
however, with normal strength of straw has been grown
in the absence of silica, except for the small amount
originally present in the seed. Lawes and Gilbert have
shown that the lack of silica is not the cause of grain
lodging. Some authorities claim that silica takes a part
in plant economy and is necessary in seed formation.
Whatever its function, it is not an important element as
plant food, and there is always an abundance in the soil
for crop purposes.

In the living plant, the mineral elements are not pres-
ent in the same form or combination as in the plant ash.
During growth, many of the ash elements are combined
with the organic compounds, for example phosphorus,
which forms phosphorized proteids and fats. The ash forms
a part of the plant tissue. When the plant is burned, the
organic compounds are volatilized, while the ash elements,
which are non-volatile, are left. The essential ash ele-
ments are absolutely necessary, as food, for the growth
and development of all crops, and plant growth is fre-
quently arrested because of the lack of a sufficient supply
for purposes of nutrition. The food requirements of in-
dividual farm crops are discussed in the "Chemistry of
Soils and Fertilizers.'-

172

AGRICULTURAL CHEMISTRY

Metals.

Summary TabIvE.
Plant ash elements.

+ 1

Occurrence.

Function.

Potassium

K2O

+

Sodium

Na^O

—

Calcium

CaO

+

Magnesium

MgO

+

Iron

Fe.Oa

1

Aluminum

Al,03

—

Manganese

MUjOg

—

Non-metals.

Phosphorus

P205

+

Sulfur

S03

+

Silicon
Chlorin

SiOj

—

Mainly in the ac-
tive growing parts
of plant leaves and
stems.

Stems and roots.

Leaves and stems.

Seeds and leaves.
Leaves and stems.

Lower parts
plants.

Lower parts
plants.

Seeds.

of
of

Assists in formation
of starch, carbohy-
drates and in plant
growth in general,
and makes plants
vigorous.

No function.

Assists in formation
of plant cells, and
makes plants hardy.

Aids in seed forma-
tion.

Aids in chlorophyl
formation.

No function.
No function.

Leaf action and for-
mation and move-
ment of proteids.

Production of pro-
teids.

No apparent function

No apparent function

Stems and leaves.
Lower parts.

Problem i. — How many pounds of potash are removed from an
acre of soil yielding 150 bushels of potatoes?

The potatoes weigh 60 pounds per bushel. 150 X 60 ^ 9,000
pounds, total yield of potatoes. The potatoes contain 24 per cent,
dry matter (see Table). This dry matter contains 3.8 per cent.
ash. Hence 2,160 pounds dry matter contain (216 X 0.038 ;= 81.9)
81.9 pounds ash. 60 per cent, of this ash is potash ; or (81.9 X
0.60) 49.1 pounds are potash. Therefore, 150 bushels of potatoes

WATER CONTENT AND ASH OF PLANTS

173

air dry, approximately 87
per cent.

approximately 90
per cent.

OOoj ^ 01 ^1 Cn 0\.P>. OS K5 CO as 0^^ OJW-t^OowNJKJOJK)

b bo op
0 0 0

oj U oj M bo w CO

C/« ^J ~J 0 0 C/i 0^

•--I 61 bo b

M C/1 10 (0

as-<I Cn Os4^ 0 OS i-i 0

n
p

K

Cn Oi 0

M K) i-H t>j K) .p^ W
Oj OsOj m m as4^

to M Ck) 10
^4 ^j 4^ -^

.p>..t^Ch> 10 loOJ to wC/j
h-H Oj Cn OssD to 0 ^) 0

?l1

000

10 4^ a\-~-t -P- 0^ 0
OS to Cfl 0 0 0 ^4

i-i OS OS to
COCn \0 (j\

4». "Oj to COi-ivDvD to
OOOC/i^ Ot0O4^

p

\o 00 fJ

C/J Oi i-i COC/1 W 4^

0 0 " 0

wOOtOMPHtOWO

P

Cn W 0>J ^J ^J M Ck»

-p' sc 00 0 0 0 ^

00 00 CO OD
Cn sC OJ 0

>- \D ^ to h-i.ti.C^ ChOs
0 COCn to 0 *-J ^ OsCn

0 OS W

10 Oj i-i w
^J OsC/1 Cn 00 00-P<.

Cn ^ OOsD

-K ■t' OsvO to to to OJ OJ

n

^ OOJ^ OS M vD OS O^Cn [a

OJ-~J-t^ tOOoto^I^JC/JCn M.PiOJ00

•<J_ ^J to Cn Cn w CC^J Oj g

■-< o sb oocln U) 00 b to J''

CnvOOOstOtoCMOJM O

OOwi-iOi-iMi-iO ?i

lotoOs .p^.^4i.^j^ji-iO\ ^CnMO

c.jajOJ4i'4^-t^OJ to.p>. ^

OOCn -^ toC/i^JCnCn^J ,!"

oovb sb -t- os^j w bsii P

OsOOJO0i-i4i'O-f^to-

4iOS OjC»j ••to* OoOJto^OMMM

>-i M to i-H Os^J CnCnCnOS O-t»t0OS

Cn 4^ Cn> Oj 4^

0

^

0

f-+.

O"

n

P
C
p

(X

0

V!

0

cn

M

l-t

P

B

0

u>

a^

-1

0

rt>

3

'Tl

cr

Hf

0

0

B

^

?

0

35

>

H

c

U)

W

t3*

*

0

0

0

>

%

s

n

Ti

cr

>

^ ,

fn

l«

R

u

g

•d

>

0

hrt

2; w

174 AGRICULTURAL CHEMISTRY

remove from the soil 49.1 pounds of potash. In the same way, the
amount of each separate element removed from the soil can be
calculated.

Problem 2. — Calculate the pounds of total ash, KgO, CaO, MgO,
and P2O5 removed in 25 bushels of wheat.

Problem j. — Calculate the same ingredients removed in 1,500
pounds of wheat straw. Compare these amounts with the corre-
sponding elements removed in the grain (Problem 2).

Problem 7.— Calculate the CaO, MgO, KoO, and P2O5 removed
in 50 bushels of oats weighing 32 pounds per bushel.

Problem 5. — Calculate the same for 40 bushels of barley weigh-
ing 48 pounds per bushel. In what respects does the mineral food
of barley differ from the mineral food of wheat?

Problem 6. — How much PO5 is removed in 15 bushels of flax?

CHAPTER XXIII
The Non-Nitrogenous Organic Compounds of Plants

223. Organic flatter.— The organic matter of a plant
or material of any kind is that portion which can be
converted into volatile or gaseous products ; it is
the combustible part, and is simply a mechanical mix-
ture of the various organic compounds, as starch, sugar,
and fat, of which the material is composed. The term
organic compounds was originally applied to those bodies
which it was believed could be produced only as the re-
sult of life processes, but it is no longer used in that sense
because many of the organic compounds are now produced
in the laboratory by synthetic methods independent of
life processes. The organic matter of a substance is ob-
tained by subtracting the ash from the dry matter. The
dry matter of wheat, for example, contains 2. 10 per cent,
ash and 97.90 per cent, organic matter. The organic
matter of plant and animal bodies includes a number of
classes and types of compounds.

224. Non-Nitrogenous and Nitrogenous Organic Com-
pounds.— For purposes of study, the organic compounds
of animal and plant bodies are divided into two large
classes : (i) nitrogenous, and (2) non-nitrogenous. This
division is made on the presence or absence of the element
nitrogen. The nitrogenous or nitrogen-containing com-
pounds are those in which the element nitrogen is in
combination with carbon, hydrogen, oxygen, and small
amounts of other elements, while the non-nitrogenous

176

AGRICUIvTURAL CHEMISTRY

compounds are those which contain no nitrogen but are
composed of carbon, hydrogen, and oxygen. Starch,
sugar, and fat are tj'pes of non-nitrogenous compounds,
while albumin, casein, and fibrin are types of the nitroge-
nous.

225. Classification of Non=Nitrogenous Compounds. —
There are six large divisions of the non-nitrogenous com-
pounds : (i) carbohydrates, (2) pectose substances, (3)
fats, (4) organic acids, (5) volatile or essential oils, and
(6) mixed compounds. Each division is, in turn, di-
vided into various subdivisions and groups :

f I . Carbohydrates,
Cellulose,
Starch,
Sugar,
Pentosans,
Gums.
Pectose substances (jellies).

{I. Olein,
2. Stearin,
3. Palmitin, etc.

!i. Tartaric,
2. Oxalic,
3. Malic, etc.
Volatile or essential oils.
Mixed compounds.

Carbohydrates

226. General Characteristics. — The carbohydrates are
the first subdivision of the non-nitrogenous compounds,-
and include the starches, sugars, gums, and cellulose and
pentosan bodies. They form the largest group of or-
ganic compounds in plants, and in many plants and food

Organic non-nitrogenous
compounds.

ORGANIC COMPOUNDS OF PLANTS 1 77

materials, are present largely as starch. The carbohy-
drates occur in plants in three physical forms : ( i ) As
the framework of the plant cells, as cellulose, (2) in
solution in the plant sap, as sugar, and (3) deposited as
solid substances within the plant cells like starch. In
coarse fodders, as hay, they are largely in the form of
cellulose and pentosan bodies. While the various carbo-
hydrates differ chemically and physically, they all possess
a few common characteristics : ( i ) they are all neutral
bodies, and (2) they all contain twice as many hydrogen
as oxygen atoms in their molecules. The H and O are
present in the same proportion as found in water, viz.,
2 atoms of H and i of O. In starch, CgHj^O^, the H and
O would form 5H2O.

Cellulose

227. Occurrence.— Cellulose is found most abundantly
in the stems, roots and leaves of plants, particularly at ma-
turity . Cellulose is the structural
basis of the vegetable world, and
forms the framework of every
plant cell. In some plants it is
the most abundant material pres-
ent ; in hay and coarse fodders
it makes up from 30 to 40 per

, r -v J , , o Fig- 72.— CeU structure of

cent, of the dry matter. Crops piaut tissue.

like cotton, flax and hemp contain large amounts, and

are cultivated mainly for the cellulo.se which they yield.

228. Physical Properties. — Pure cellulose is a colorless,
in.soluble material, differing in texture according to its

178

AGRICULTURAI, CHEMISTRY

Fiff- 73.— Flax fiber.

-ource. In hemp, it is flexible and tenacious, while in
wood, it is hard and compact, in
the pith of the elder, it is elastic,
in the potato, porous, and in ger-
minating seeds, loose and spongy.
Cotton and filter-paper are ex-
amples of nearly pure cellulose.
The proportion and properties
of cellulose in a food influence
its digestibility. Some foods are
less valuable because of the
tenacious character of the cellu-
lose, which prevents the cells

from undergoing disintegration and digestion.

229. Chemical Properties. — Cellulose is composed of
carbon, hydrogen and oxygen. Its formula is CgHjuOs.
Cellulose from one source may contain a different multiple
of CgHioOj than that from another source. In young and
growing plants, the cellulose is in a hydrated condition ;
that is, water is chemically united with the cellulose
molecule, as (C5Hi„05.H20)n. Hydrated cellulose is more
readily acted upon by chemicals than are other forms.
As the plant develops, the cellulose is gradually dehy-
drated and this is one reason why cellulose, at different
stages of growth, has a different food value. Ligno-
cellulose is found in wood and many mature plants. It
contains a larger per cent, of carbon than cellulose.

230. Function and Value. — In the plant, the function
of cellulose is to form the structural part of the cell walls.
It constitutes the main part of the walls of every plant cell.

ORGANIC COMPOUNDS OF PLANTS 1 79

In seeds, it is a reserve material, finally used as food by
the young plant. Commercially, cellulose is used for
making paper, cloth, guncotton and other explosives, and
is extensively used in the arts.

231. Food Value. — The food value of cellulose depends
upon its degree of hydration. Hydrated cellulose, when
digested, has practically the same food value as starch,
lyignocellulose is indigestible, and has no food value.
Indirectly, a minimum amount of cellulose imparts a
mechanical value to a food by acting as an absorbent for
concentrated waste products. When crops are cut and
cured while some of the cellulose is in a hydrated condi-
tion and but little has passed into the ligno form, the
cellulose is valuable as food.

232. Amount of Cellulose in Plants. — Cellulose is
found more abundantly in the stems and leaves of plants
than in the seeds. In the straw of wheat, oats, rye, and
barley, it makes up from 35 to 45 per cent, of the dry
material. It also constitutes a large portion of the roots
of plants. In seeds, the amount of cellulose is small, and
usually ranges from 2 to 5 per cent., while in wood, the
amount is large, and ranges from 50 to 80 per cent. In
tables of analyses, the cellulose is usually included with
other bodies under the head of crude fiber.

233. Crude Fiber. — Crude fiber includes the cellulose,
lignin and other bodies which make up the framework of
vegetable substances. In vegetable foods, as flour and
the cereal products, the amount of crude fiber is small
compared with that in many other plant bodies. Crude

l8o AGRICULTURAL CHEMISTRY

fiber and cellulose are not identical terms. In the chem-
ical analysis of plants, the crude fiber is determined b)^
first digesting the material in dilute sulfuric acid to
dissolve all soluble bodies as sugar, hydrolyzed starch,
some of the proteids and related bodies. The substance
is then digested with dilute sodium hydroxid to remove
all compounds which have failed to dissolve in the acid.
Crude fiber and insoluble mineral matter are about the
only substances which are insoluble in the dilute acid and
alkali, hence the fiber is obtained by dissolving all other
compounds and deducting the insoluble mineral matter
left. For the determination of cellulose more exact
methods have been devised. The crude fiber determina-
tion, however, is valuable because it shows the amount
of fibrous material contained in plants.

Experiment 45. — Preparation of cellulose. Place in a beaker
about I gram of ground straw or hay ; add 200 cc. of water, and
20 drops of H2SO4. Boil on the sand-bath twenty minutes, and
after the material settles, pour off the liquid, then add 100 cc. water,
and wash thoroughly by decantation. Add 200 cc. water and 4 cc.
NaOH solution, boil twenty minutes, and wash the fibrous material
as before. Place some of the crude fiber in a test-tube, add 5 cc.
HCl, 10 cc. HjO, and a crystal of KCIO3 ; heat, and then wash the
cellulose product.

Questions, (i) What element was liberated by the action of
HCl upon the KCIO3 ? (2) What effect did this element have in the
bleaching and purification of the crude fiber? (3) In what other
experiment has this element been used as a bleaching reagent?

(4) When examined with a lens, how did the cellulose appear ?

(5) Is cellulose soluble in dilute acids? (6) Why were the dilute
acid and alkali solutions used in this experiment? (7) What be-
comes of the ash or mineral matter in the material used in this ex-

ORGANIC COMPOUNDS OF PLANTS l8l

periment? (8) What does this experiment show in regard to the
properties of cellulose ?

Starch
234. Occurrence. — Starch is found most abundantly in
the seeds, roots, and tubers of plants, being stored up in
those parts which are concerned with new growth.
During growth, starch is produced in the leaves of all
green plants ; at maturity, it is stored in the seed or tuber.
It is present in the plant cells as granules which have
regular organized forms.

235- Physical Properties. — The starch granules from
a given cereal are always constant in form and physical
properties. Each grain is composed of overlapping layers
which can be observed under the microscope. The walls
of the layers are composed of a material called ' ' starch
cellulose ' ' ; between the walls is the pure starch known
as granulose. All starch grains have a somewhat similar
general structure. Starch is insoluble in cold water, be-
cause the walls of starch cellulose prevent the water from
dissolving the pure starch. In hot water some of the
granulose is dissolved and a paste is formed. Pure dry
starch is tasteless and odorless. Starch is exceedingly
hydroscopic, and commercial starch always contains from
10 to 12 per cent., or more, of water. A food which
contains a large amount of starch will vary in moisture
content and weight according to the hydroscopicity of the
air. The starch grains obtained from different cereals
and food products vary in form according to the source
from which they are obtained. Wheat starch is circular

l82

AGRICULTURAL CHEMISTRY

in outline, and has a slightly concave center. There are

but few markings or
rings (see Fig. 74).
The granules vary
in size from 0.05 to
o.oi millimeter in
diameter. Corn-
starch is somewhat
smaller (0.02 to 0.03
millimeter), more
angular than wheat
starch, and has a
Fig. 74.— Wheat starch. star-sliapcd Center

or helium (see Fig. 75). Oat starch is composed of

a number of small

segments forming a

compound grain, or

mass, each segment

in itself a complete

structure. Barley

and rye starch

grains are somewhat

similar to wheat.

In some vegetables,

as the parsnip, the

starch grains are

minute.

Fig- 75-— Cornstarch.

236. Chemical Properties. — Starch is composed of car-
bon, 44.44 per cent. ; hydrogen, 6.17 per cent. ; and
oxygen, 49.39 per cent. Its formula is (C5Hio05)n. The

ORGANIC COMPOUNDS OP PI.ANTS 1 83

value of n has been variously estimated from 2 to 200.
The different starch grains, as of wheat, corn and oats,
are all composed of the same elements, C, H, and O, and
differ in form because these elements are put together in
a different way in each. When acted upon by heat, as in
the popping of corn, the starch grains are ruptured. At a
temperature above 120° C, starch is changed to dextrin.
In the presence of water and dilute acids, starch gradually
undergoes hydration ; that is, water is chemically added
to the molecule. By the joint action of heat, ferments,
and various chemicals, starch is converted into a number
of products, as soluble starch and dextrose. In the
presence of iodin, starch is colored blue, different kinds
of starch giving different shades and tints. The nature
and mechanical form of the starch granules in a food,
determine, to a slight extent, its rapidity and ease of di-
gestion. Some starches are more easily digested than
others, and all undergo important chemical and physical
changes in the cooking and preparation of food. Since
starch makes up such a large portion of many human and
animal foods, its composition, properties, and food value
are of prime importance.

237. Function and Value. — In the seed, starch is a
reserve form of food for the use of the young plant before
it is able to obtain its own food ; in roots and tubers also,
it is' stored up for that purpose. Many crops, as pota-
toes, corn, and sago, contain so much starch that they
are often cultivated for starch-making purposes. Starch
is obtained mechanically from potatoes by first pulping
to break the cells, and then washing the pulped mass

1 84 AGRICULTURAL CHEMISTRY

with water from which the starch slowly settles. In the
arts, starch is used in many ways. As a food, it is used
mainl}^ in its original form associated with the other or-
ganic compounds with which it is found in plants.

238. Food Value of Starch. — Starch is a valuable nu-
trient, and when digested produces heat and energy.
When burned in the bomb calorimeter i pound of
digestible starch produces i860 calories. A calorie
is the unit employed for measuring heat, and is
the amount of heat required to raise i kilo of water 1° C,
or approximately i pound of water 4° F. One gram
of starch yields 4.2 calories. Pure starch alone is inca-
pable of sustaining life because it contains eo combined
nitrogen, and does not supply any material for repairing
the tissues of the body or for the construction of new
nitrogenous tissue. When associated with nitrogenous
compounds, starch can be used by the body for the pro-
duction of fat as well as for the production of heat
and energy.

239. Amount of Starch in Plants. — In grains, the
amount of pure starch ranges from 50 to 75 per cent, of
the dry weight of the material ; in hay and forage crops,
it is small, usually less than 2 per cent. The amount of
pure starch in some of the cereals and farm crops is ap-
proximately as follows :

Pure starch.
Per cent.

Wheat 68

Wheat flour 72

Oats 55

Corn 75

ORGANIC COMPOUNDS OF PLANTS 1 85

Pure starch.
Per cent.

Rice 78

Potatoes 80

Wheat bran 8

Straw less than i

Hay I to 3

Experiment 46. — Preparation of potato starch. Reduce one or
two clean potatoes to pulp on the grater. Tie the pulp in a clean
cloth and squeeze into a large cylinder filled with water, occa-
sionally dipping the bag into the water. Allow the cylinder to

Fig. 76. — Obtaining starch from potato.

stand for twenty minutes, or until the starch has all settled ; pour
off" the water. If the starch is not clean, wash by adding more
water, and allow it to settle again ; then pour off the water. Leave
the cylinder in the desk until the starch is dry. Save this starch
for the following tests: Tests for starch. Place 0.5 gram of starch
in a test-tube, about one-half full of water. Shake the test-tube, boil,
and filter ; then to this filtrate add a few drops of iodin. Treat a
second portion of starch with cold water and then add iodin.

Questions, (i) What was the difference in the action of hot and

l86 AGRICULTURAI^ CHEMISTRY

cold water upon starch ? (2) How did this difference show itself
in the tests? (3) Why in the one test-tube were there a blue mass
and a clear liquid, and in the other opposite results ?

240. Dextrin is a carbohydrate which has the same
general formula as starch from which it differs in struc-
tural composition. Dextrin is produced from starch by
the action of heat. At a temperature of 163° C. moist
starch is changed to dextrin. When this change takes
place, nothing is added to or taken from the starch mole-
cule. The three elements, C, H and O, are simply rear-
ranged in a different way in the new molecule. Dextrin
is not found naturally in food products to any apprecia-
ble extent, but is present in starch-containing foods which
have been subjected to the action of heat. The brown
crust of bread is composed mainly of dextrin. Dextrin
is soluble in water, and is more readily digested than
starch, but has the same general fuel and energy-produ-
cing value.

Experiment 47. — Preparation of dextrin. Place about 2 grams
of flour in a porcelain dish ; heat cautiously on a sand-bath for five
minutes constantly stirring, so that it will not burn. When cool,
add three times its bulk of water and heat nearly to boiling ; ob-
serve the appearance of the solution ; then filter. The filtrate con-
tains dextrin. To a portion, add twice its bulk of alcohol; the
dextrin is precipitated. To another portion, add a few drops of
iodin solution ; blue color indicates soluble but unaltered starch.

Questions. ( i ) What agent was employed to change the starch
to dextrin ? (2) How does dextrin differ from starch in solubility?
(3) Is dextrin soluble in alcohol ? (4) In what ways does dextrin
differ from starch?

241. Structural Formulas. -Cellulose, starch, dextrin
and iuulin have the same general formula (CgH^oO^jn, but

ORGANIC COMPOUNDS OP PLANTS 1 87

all differ in both physical and chemical properties. This
is because the elements, C, H and O, are put together in
different ways in the three compounds. For example, a
pile of bricks may be put together to form one structure,
and then again in different ways to form other structures;
in each structure there are the same number and kinds
of bricks. So in the molecules of starch, dextrin, inulin
and cellulose, there are the same number and kinds of
atoms, but in each they are combined in a different way.
In the study of the composition of plants, organic com-
pounds are frequently met with which have the same
general composition, but different chemical and physical
properties. Whenever two compounds have the same
general formula and percentage composition, but differ-
ent chemical and physical properties, the difference is
said to be one of structural composition.

Sugar

242. Classification of Sugars — As commonly used,
the term sugar is applied to the product obtained from
sugar-cane or sugar-beets. As used in chemistry, it in-
cludes a large class of compounds of which maple-, cane-,
and beet- sugar are examples of only one division. The
two main classes of sugars present in plant bodies are
sucrose and dextrose; occasionally, other sugars are found.

The sucrose group includes cane-, beet-, maple-, milk-,
and malt-sugar. These sugars have the general formula
C12H22O11, and are characterized by the molecule contain-
ing 12 atoms of carbon. The dextrose group includes
glucose, levulose, galactose, and all sugars having the
general formula CgHjjOg. This group is characterized by

1 88 AGRICULTURAI, CHEMISTRY

the molecule containing 6 atoms of carbon. The term
monosaccharide is applied to the dextrose group, and
disaccharide to the sucrose group.

243. Occurrence of Sucrose. — Sucrose is found in plants
in largest amounts of any of the sugars. Juices from the
sugar-cane and sugar-beet contain from 12 to 18 per cent.
It is also present in small amounts in seeds and cereal
products. From 1.5 to 2 per cent, is found in sweet corn
and about 0.50 per cent, in wheat flour. In some fruits,
as apples, sucrose is present to the extent of 5 per cent,
or more.

244. Physical and Chemical Properties of Sucrose. —

The chemical and physical properties of sucrose obtained
from the sugar-cane or sugar-beet are alike in all respects.
When the two sugars have been subjected to the same
degree of refining, they are identical. When examined
under the microscope, sucrose is in the form of regular
crystals, as shown in the illustration (see Fig.
77). At 160° C. sucrose crystals melt, and
when cool form a colorless, glassy mass. A
_,. „ concentrated solution boils at a little above

Fig. 77.— Su-

crosecrystai. joo° C. At i6o° C. a browu product known
as barley sugar is formed. At 200° C. sucrose is decom-
posed, and gases, as carbon monoxid, carbon dioxid and
methane, are given off. In concentrated solutions, a tem-
perature of 100° C. causes an inversion ; that is, the su-
crose molecule is split up and two new sugars are formed,
namely : dextrose and levulose. Hence, in the refining
of sugar, the concentration must be carried on in vacuum

ORGANIC COMPOUNDS OF PI.ANTS 1 89

pans. In the presence of all acids, even dilute organic
acids, hydrolysis or inversion of sucrose takes place.

245. Milk-Sugar (lactose) is found in cow's milk to
the extent of 4.5 to 5 per cent., and is present in the
milk of all mammals. It has the same general but a dif-
ferent structural composition from sucrose.

246. rialtose is a sugar produced in the malting of
barley and other grains by the action of ferments upon
starch, the reaction being

2 CfiHioOs + HoO =- CioHoaOn.
Maltose is not found to any extent in plant bodies, but is
present in prepared foods which have undergone the malt-
ing process.

247. Inversion of Sucrose. — When sucrose is acted
upon by heat and dilute acids, as well as other chemicals,
inversion takes place. One molecule of water is chemi-
cally united to one molecule of sucrose which splits up
and forms the two sugars, levulose and dextrose.

Sucrose. l,evulose. Dextrose.

C,H,,0,, + H,0 = C,H,,Oe + C,-R,fi,.
This process takes place in the ripening of fruits and in
the curing of many fodders, as well as in the cooking and
preparation of human foods.

Experiment 48. — Inversion of cane-sugar. Place 2 grams
sugar, 30 cc. HjO, and 2 cc. HjSO^ in an evaporator. Heat
fifteen minutes on a sand-bath, replacing the water lost by
evaporation. Neutralize with CaCOj and filter, adding more
water if necessary for filtration. Test 5 cc. of the filtrate with
an alkaline solution of copper sulfate (Fehling's solution)
as directed in Experiment 34. Take o.i gram of sugar, dis-

190 AGRICULTURAI, CHEMISTRY

solve in 10 cc. cold water, add 2 cc. alkaline copper sulfate solution,
and heat cautiously for about a minute. Cane-sugar, unless in-
verted, gives no reaction with copper sulfate solution. Compare
this result with the first test. Observe that in the first test the same
precipitate is obtained as in Experiment 34.

Questions, (i) What is meant by inversion of cane-sugar? (2)
Why was hot sulfuric acid used? Write the reaction. (3) Why
was CaCOj used? (4) What becomes of the calcium salt when the
solution is filtered ? (5) What was the result when the filtrate was
heated with alkaline copper sulfate solution (Fehlings' solution)?
(6) Did the sucrose, when tested, give any reaction with this
reagent? (7) Under what condition in nature does this process of
inversion take place ? (8) What are invert sugars?

248. Refining of Sugar. — At the present time, the
larger portion of commercial sugar is obtained from sugar-
beets. In the diffusion process of manufacture, the beets,
after cleaning and slicing, are passed into large tanks,
where they are subjected to water under pressure which
removes the sugar by liquid diffusion. The impurities
associated with the sucrose are precipitated with lime
water, Ca(0H)2, the excess of lime being removed by
carbon dioxid gas which converts the calcium hydroxid
into insoluble calcium carbonate. For the purpose of pro-
ducing the pure lime and the carbon dioxid gas, lime-
stone is burned in specially constructed kilns at the sugar
factory. After the removal of the impurities and
lime, the solution containing the sugar is concentrated in
a large vacuum pan and allowed to crystallize ; the crys-
tals are then washed in centrifugal washing machines
and granulated. Commercial sugar is ordinarily about
99 per cent, pure sucrose.

249. Occurrence of Dextrose. — Dextrose occurs widely

ORGANIC COMPOUNDS OF PLANTS I9I

distributed in nature. It is found in small amounts in
the sap of saccharine plants, in seeds, ripe fruit, honey,
animal tissues, and all food products in which the
sucrose has undergone inversion.

250. Chemical and Physical Properties. — Dextrose is a
solid, white substance which gives off water from its mole-
cule when heated to 170° C. At 200° C, volatile gases
and acid products are formed. Acids and alkalies act
.upon dextrose and produce a large number of compounds.
Dextrose is capable of undergoing a number of different
kinds of fermentation, alcohol, succinic acid, lactic acid,
and glycerol being some of the products formed. When-
ever foods which contain dextrose are exposed to favor-
able conditions, fermentation takes place. Dextrose is
produced commercially by the action of dilute acids upon
starch. The acid causes a molecule of water to unite
chemically with a molecule of starch.

CgHioOs + H^ = CgHigOg.
The thick syrup that is formed after the acid is neu-
tralized is called glucose syrup. If a solid mass is pro-
duced, it is called grape-sugar.

Experiment 49. — Preparation of glucose. Add 20 drops HjSO^
to about 70 cc. water in an evaporator. Heat on the sand-bath
until the boiling-point is reached. Then add 2 grams of pulver-
ized starch. Observe the appearance of the starch immediately
after adding. Heat twenty-five minutes, stirring occasionally, and
replacing the water should too much evaporate. Add CaCOs to
neutralize the H2S0.j ; when neutral to test paper, filter, washing
the contents of the filter with 25 cc. of water. Take a few drops of
the filtrate and test with iodin for starch. Then evaporate the rest
of the filtrate to about 20 cc. and observe its appearance.

192 AGRICULTURAI, CHEMISTRY

Tests for glucose. Place about 3 cc. of glucose solution in a test-
tube, add 3 cc. alkaline solution of copper sulfate, called Fehling's
solution ( see Experiment 34 ) , and heat. Then take about o. i gram
of glucose from the shelf bottle, dissolve it in 5 cc. water, add 3 cc.
Fehling's solution. Heat, and compare with the first test.

Questions, (i) Why was sulfuric acid used in this experiment?
(2) What chemical change did the starch undergo? Write the
reaction. (3) Why was CaCOg used? Write the reaction. (4)
Was any reaction obtained with iodin for starch? (5) What was
the result when the glucose solution was added to the hot alkaline
solution of copper sulfate ? (6) How did this precipitate compare
with that obtained when glucose from the shelf bottle was used ?

251. Levulose, commonly called fruit-sugar, is formed
along with dextrose whenever sucrose undergoes inver-
sion. It has the same formula as dextrose, CgH^jOg, but
different chemical and physical properties, due to a differ-
ent structural composition. Levulose is very sweet, and
is found in many ripe fruits and vegetables. Its proper-
ties are somewhat similar to those of dextrose, but it is
more susceptible to the action of heat, acids, and alkalies,
and less to the action of ferments.

Experiment 50. — Levulose and reducing sugars from carrots.
Reduce a small clean carrot to a pulp. Place the pulp in a beaker
and add 200 cc. water. After half an hour, filter, heat the filtrate
for fifteen minutes and then filter a second time. Evaporate 50 cc.
of the filtrate nearly to dryness. Test a portion with Fehling's
solution as in Experiment 49.

Questions, (i) How was sugar separated from the carrots?
(2) What was the result when the filtrate was heated, and what
compounds were precipitated ? (3) Describe the appearance of the
concentrated filtrate. (4) What reaction was obtained with
Fehling's solution? (5) How does levulose differ in composition
and properties from dextrose ?

ORGANIC COMPOUNDS OF PI^ANTS

193

252. fliscellaneous Sugars. — A number of sugars that
do not belong to either the dextrose or sucrose group
are found in plants. Raffinose, for example, is a sugar
found in small amounts in beets and other vegetables.
It is capable of being converted into dextrose sugars by
treatment with dilute acids.

253- Optical Properties of Sugar. — Sugars are charac-
terized as optically active or inactive. Those which
have the power of turning a ray of polarized light to the
right are called dextrorotatory while those which turn the
ray to the left are called levorotatory. Polarized light
has no action upon the inactive sugars. This principle
is taken advantage of in the commercial testing of sugar
by means of the polariscope which is a piece of apparatus
so constructed that the number of degrees which a ray of

Fig. 78. — Polariscope.

polarized light is diverted in passing through a solution
of sugar can be accurately measured, and the purity of

194 AGRICULTURAL CHEMISTRY

the sugar determined. A given weight of pure sucrose
dissolved in a definite amount of water alwaj-s turns a ray
of polarized light a definite number of degrees which are
accurately measured by the polariscope. Any decrease
in purity influences proportionally the angle of diver-
gence of the polarized light. Hence, if the angle of
divergence of a commercial sugar is determined, its purity
is likewise determined.

254. Sug-ar-Beets are usually paid for on the basis
of their content of sugar and the purity of the juice.
For sugar-making purposes, the higher the content of
sugar and the purer the juice, the more valuable the
beets. Ordinaril}^ sugar-beets contain from 12 to 16 per
cent, sugar ; occasionally as low as 8 and as high as 20
per cent. In addition to sugar, the beet juice contains
other solids, as small amounts of organic acids, albumin
and pectin . When the content of solid matter is 20 per
cent, and 16 of the 20 parts are sugar, the juice has a
purity coefficient of 80 ('"/ao X 100).

255. Food Value of 5ugar. — When properly combined
and used with other foods, sugar is a valuable nutrient
for the production of heat and energy. L,ike starch, it
is incapable of sustaining life unless associated with nitroge-
nous compounds. * One pound of sugar, when burned,
yields 1.5 pounds of carbon dioxid and 0.58 pound of
water.

Ci,H,,Ai + 24O = 12CO, + H,0.
In a ration, sugar is considered as having the same
caloric value as starch, viz., i pound yields i860
calories.

ORGANIC COMPOUNDS OF PLANTS I95

256. Gums. — Closelj' related to the sugars are the
gums, like gum arabic, and those which exude from
peach and cherry trees. In the seeds of many grains,
there are also gum-like bodies. When treated with di-
lute acids, the gums are converted into dextrose sugars
and acid products. Bassorin, or mucilage, as flaxseed
mucilage, is found in a few seeds and fruits. The for-
mula for some of the gums is the same as for sucrose sugars
and dextrose.

357. Pentosans. — The pentosans are a class of carbo-
hydrates present in liberal amounts in many plants. They
are insoluble, and aid the cellulose in giving form and
structure to plant tissues. When acted upon by dilute
acids, the pentosans are rendered soluble, while true cel-
lulose is insoluble. They are called pentosans because
they yield a sugar which contains five atoms of carbon
in the molecule. When acted upon by the digestive
fluids they are rendered soluble and available as nutrients.
In some fodders they form a large part of the nitrogen-
free extract. The digestible pentosans are considered as
having the same food value as other digestible carbohy-
drates. The amount of pentosans in some common foods
is approximately as follows :

Per cent.

Hay, timothy 20

Linseed meal 12 to 15

Wheat bran 1 7 to 22

Wheat 4 to 6

Oats 12

Corn 5

Barley 5 to 7

Flour trace

258. Pectin Bodies are present in many ripe fruits and

196 AGRICULTURAL CHEMISTRY

vegetables. They are jelly-like substances, which are
soluble in hot water, and are commonly known as fruit
jellies. When treated with dilute acids, digestive fluids,
and other reagents, the pectin bodies are converted into
dextrose sugars and other products. Potatoes, turnips,
beets, and all fruits contain pectin. In unripe fruits, and
in some uncooked vegetables, the pectin is in the form of
acid bodies which are insoluble and indigestible. In the
last stages of ripening, the pectin of fruits and vegetables
undergoes a change to soluble forms. Soluble pectin is
considered to have the same food value as the soluble
carbohydrates.

EA'periment 5/. — Pectose from potatoes. Reduce a small clean
potato to a pulp. Squeeze the pulp through a clean cloth into a
beaker, add 10 cc. H2O, and heat on a sand-bath to coagulate the
albumin. Filter, add a little hot water if necessary. To the filtrate
add a little alcohol. The precipitate is the pectose material.

Questions, (i) Is the pectose from the potato soluble? (2)
Is pectose coagulated by heat? (3) Is it soluble in alcohol? (4)
In what ways does pectose differ from sugar? (5) In what ways
does it resemble sugar ?

259. Nitrogen=Free Extract. — In the processes of chem-
ical analysis of plants and foods, the chemist determines the
water, ash, crude protein, ether extract, and crude fiber,
and classes the remainder in one group or division called
nitrogen-free extract. Wheat, for example, contains :

Per cent.

Water 9.25

Ash 2.95

Crude protein 13-25

Ether extract 2.20

Crude fiber 2. 25

Total 29.90

100 — 29.90 ^= 70.10 per cent, nitrogen-free extract.

ORGANIC COMPOUNDS OF PLANTS I97

The term nitrogen-free extract means that the bodies
contain no nitrogen ; they are nitrogen-free or non-nitroge-
nous, and are soluble in dilute acids and alkalies. The
nitrogen-free extract of wheat is composed mainly of
starch ; in some foods, as carrots, it is largely sugar. In
human foods, the nitrogen-free extract is composed
mainly of carbohydrates as starch and sugar, while in
animal foods, it consists of pentoses and a large number
of compounds dissimilar in character and food value. In
plant bodies, the nitrogen-free extract usually constitutes
the largest of any of the groups of compounds. Meats
and animal products, except milk, contain only very
small amounts.

Fats

260. Presence in Plants — Fats and oils form one of
the subdivisions of the non-nitrogenous compounds of
plants. Fat is present in nearly all plants, but in smaller
amounts than the carbohydrates. The fat in plants is
produced from starch. For example, in flax, there is
more starch than fat when the plant is growing, but in
the mature plant, there is more fat than starch, due to the
.starch being converted into fat. This change of starch
to fat can take place only in the plant cells ; fat, as yet,
cannot be made synthetically. During the process of
germination, the fat of seeds is changed back to starch.
While fat is present in nearly all parts of plants, it is
found most abundantly in the seeds, as of flax, rape and
cotton, which are often called oil seeds. Fat occurs in
the form of minute oil globules within the plant cell, and
is removed mechanically by the aid of heat and pressure,

198 AGRICULTURAL CHEMISTRY

as in the manufacture of linseed, rape, cottonseed and
other oils. It is also extracted by means of solvents as
benzine and carbon disulfid. In roots and stems, fat is
found only in traces. In leaves, it is often present in the
form of a waxy coating, while in nuts it is frequently
stored up in large amounts in the kernel.

261. Physical Properties. — Fats are all characterized
physically by being insoluble and of a lower specific
gravity than water. There are a great many separate
fats, and each has its own specific gravity and melting-
point. As commonly found, they are not simple bodies,
but mechanical mixtures of various separate fats, as
stearin, palmitin, and olein. The fats are all soluble in
ether, chloroform and turpentine, and differ in physical
properties according to the proportion and kind of fats
present. When examined under the microscope, some
have optical properties and definite crystalline forms.

262. Chemical Composition. — Fats are all characterized
by having a high per cent, of carbon and a low per cent,
of oxygen. For example, in stearin Cj^HugOg, there are
in the molecule 57 atoms of carbon, and 6 atoms of
oxygen. In starch and carbohydrates in general, the per
cent, of oxygen is greater, and of carbon, less than in
fats.

Ui^TiMATE Composition of Fats.

stearin. Palmitin. Olein. Starch.

Per cent. Per cent. Per cent. Per cent.

Carbon 77.6 75.9 77.4 44.44

Hydrogen 12.4 12.2 11. 8 6.17

Oxygen lo.o 11. 9 10.8 49-39

ORGANIC COMPOUNDS OF PLANTS IQ^

Fats are organic salts, the basic part consisting of the
glycerol radical C3H5 which is combined with a fatty acid.
Glycerin is the basic constituent common to all fats.
One fat, as stearin, differs from another, as olein, by
containing a different fatty acid in combination with the
glycerol radical. When the simple fats are separated into
their component parts, the acids formed are : stearic,
palmitic, oleic and butyric.

Some of the fatty acids, as stearic and palmitic, are
solids, while others, as butyric, are volatile. Those fatty
acids which distil with boiling water are called volatile
fatty acids. Butter, for example, contains nearly 5 per
cent, of volatile fatty acids, present mainly in the form of
butyric acid. Some of the fats undergo fermentation and
become rancid, as butterin in butter, while others slowly
take up oxygen from the air and undergo oxidation.
The chemical and physical properties of the fats in plants
and foods are determined by the kinds and amounts of
the separate fats present. Olein, stearin and palmitin
are always present in larger amounts than are other fats.

263. Stearin (Cj^HugOg) is a solid fat with a high melt-
ing-point, 69.4° C. Beef and mutton tallow and animal
fats in general are composed mainly of stearin. When
pure, it is a white and tasteless body, and has a defi-
nite crystalline structure. Stearin predominates in all
hard fats.

264. Palmitin (CgiHggOg) is a white, solid fat obtained
from butter, palm oil and human fat. When chemically
pure, it is tasteless, and crystallizes in the form of tufts
and needles. It has a melting-point of 63° C. Its

200 AGRICULTURAL CHEMISTRY

general properties are somewhat similar to those of
stearin.

265. Olein (CjjHio^Og) at moderate temperatures is a
liquid. It solidifies at 4° C. Olein predominates in the
oil of fish, as sperm oil and cod-liver oil. It is also present
to a great extent in many vegetable oils, as olive oil.
Whenever olein predominates, the fat is a liquid.

266. Miscellaneous Fats.— In addition to the three
fats mentioned, there are others, as butj^rin, the charac-
teristic fat of butter, and linolein, the characteristic fat of
flaxseed.

267. Saponification is a chemical change brought about
by the action of an alkali, as potash or soda, upon a fat.
An exchange takes place between the glycerol of the fat
and the metal of the alkali. Glycerine is a base, but
potash is a stronger base ; hence the potash replaces the
glycerol and forms salts, as potassium stearate or palmitate,
according to the fat used.

Experiment ^2. — Saponification. Weigh about 20 grams of lard
into an evaporator. Melt the lard, but do not heat above 50° C.
Dissolve 10 grams NaOH in about 40 cc. tpater in a beaker. (Do
not let the NaOH come in contact with the scale pan.) Add this
solution to the evaporator, stirring constantly, and leave the evapo-
rator on the vrarm sand-bath, with a low flame underneath, for
40 to 50 minutes. Then place on the sand-bath in the desk until the
following day when a good soap should have formed. Dissolve a
little of the soap thus produced in a test-tube with 20 cc. water.
Divide the solution into two parts ; to one add a little salt, and to
the other a few drops of HCl.

Questions, (i) Why was NaOH used in this experiment, and
what portion of the fat did it replace ? ( 2 ) What other materials

ORGANIC COMPOUNDS OF PLANTS 20I

could be used in place of NaOH? (3) What influence did the salt
have upon the soap solution? (4) What was the result when
HCl was added to the soap solution? (5) Why is it neces-
sary to weigh both the lard and the NaOH ? (6) What would be
the result if the fat and alkali were taken in different proportions
from those used in this experiment? (7) Why does soap form an
insoluble mass with hard waters ?

268. Fatty Acids. — Formic acid, found in pine needles
and in red ants, has the formula H2CO2 which is also
written HCOgH. Acetic acid has the formula H.CH^.
CO2H, and differs from formic acid simply in containing
CH2 more than found in formic acid. If CH^ were added
to acetic acid, H.CjH^.CO — H, propionic acid would be
produced. This is present in some plants. In like
manner, butyric acid can be produced from propionic
acid. By the addition of CH^, about twenty acids can be
formed in the way described. This list includes palmitic,
stearic and other acids found in fatty bodies and named
fatty acids ; various of these are present in nearly all
foods. When a series of compounds, like the fatty acids,
show^s a uniform difference between two adjacent members
the term homologous series is employed.

269. Waxes. — Wax is similar in composition to fat,
but contains an ethyl radical in place of the glycerol
radical. Beeswax, for example, is composed of palmitic
acid and ethyl radicals. Waxes, like fats, undergo saponi-
fication and are considered as having the same food
value.

270. Food Value of Fat.— Fat is the most concentrated
non-nitrogenous nutrient of foods. On account of con-

202 AGRICULTURAL CHEMISTRY

taining such a large amount of carbon and small amount
of oxj^gen, fat, when either burned or oxidized as food,
produces 2.25 times more heat than the same weight of
starch or sugar. One gram of fat j'ields 9.2 calories, and
I pound, 4225 calories. The fact that so much more
heat is produced from the oxidation of fat is apparent
when the "products of oxidation of starch and fat are
compared.

stearin.
C57H„oOe + 163 O - 57CO, + 55H2O

890 2508 990

I pound of fat produces 2.8 pounds
CO2 + I.I pounds of water.

starch.

CfiHioOs + 120 = 6CO2 + 5H2O

162 264 90

I pound of starch produces 1.6

pounds CO2 + 0.56 pound HjO.

890 parts, by weight, of fat produce, when burned, 2508
parts, by weight, of carbon dioxid and 990 parts
of water. 162 parts, by weight, of starch produce
264 parts, by weight, of carbon dioxid and 90 parts of
water. One pound of fat yields 2.8 pounds of carbon
dioxid and 1. 1 pounds of water, while one of starch yields
1.6 of carbon dioxid and 0.56 of water. Fat produces
approximately 2.25 times more heat than starch.

271. Amount of Fat in Plants and Foods.- -The

amount of fat in various plant substances ranges from a
few hundredths of a per cent, in tubers to 35 per cent,
and more in flaxseed. Of ordinary grains, oats and corn
are the richest in fat and contain from 3.5 to 5 per cent. ,
while wheat and rye have about 2 per cent. each. In
hay, the amount of pure fat is less than 2 per cent., and

ORGANIC COMPOUNDS OF PLANTS 203

in straw it is less than i per cent. In nearly all food
products, the per cent, of pure fat is included with the
ether extract.

Experime7it 53. — Fat from wheat germ. Place 2 grams wheat
germ in a test-tube, and add gasoline until the test-tube is about
one-third full. Cork and shake at intervals of three or four min-
utes. Do not let the gasoline come near the gas flame. Filter into
a clean porcelain dish, and place the dish in an open window until
the gasoline is evaporated. Observe the residue of fat.

Experhnent §4. — Fat from yolk of egg. Repeat the preceding
experiment, using one-fourth of the yolk of a hard boiled egg, and
5 cc. ether instead of gasoline.

Questions. ( t ) What was the solvent used for separating the
fat from the wheat germ ? ( 2 ) From the yolk of the egg ? ( 3 )
Describe the fat obtained from the wheat germ. (4) From the
yolk of the &^%. (5) How were the solvents removed in these
experiments? (6) Are fats volatile bodies ? (7) Why do fats ob-
tained from different sources vary in appearance and properties ?

272. Ether Extract. — The term ether extract is applied
to that class of compounds which is soluble in ether. In
the case of human foods, the ether extract consists largely
of fats and oils with variable amounts of waxes, resins,
chlorophyl, vegetable coloring-matters and nitrogenous
and phosphorized bodies as lecithin. The value of the
ether extract depends entirely upon its source ; in milk,
meats, and cereals and their products, the ether extract
is nearly pure fat, while in many vegetables it is less
than half fat. Methods of chemical analysis have not,
as 5'et, been sufficiently perfected to allow the separation
and determination of the pure fat of all materials. The
ether extract is obtained by placing a small weighed
amount of the dry material in a tube, 3, (Fig. 79) which

204

AGRICULTURAL CHEMISTRY

is then placed in a glass extractor connected with a small
weighed flask containing ether. The flask is immersed
in a water-bath heated by a gas
burner, the ether is volatilized,
and the vapor passes through
openings 2 and 4 into the con-
denser where it is cooled and
falls back in drops from point 4
on the substance at 5. The
ether percolates through the sub-
stance and returns to the flask.
The fats and ether-soluble mat-
ters are not volatilized but remain
in the flask while the ether is
vaporized and condensed again
and again. After the extraction
is completed, the ether is distilled
from the flask, the ether extract
dried and weighed, and the per-
centage amount calculated. While
the process appears to be simple,
it is a difficult operation to con-
trol, because even after many-
days' extraction, some materials
will continue to give up ether
extract, and unless unusual care
Fig. 79.— Ether extractor. is taken somc of the fats are
oxidized. Then, too, the ether extract is liable to be
contaminated with impurities if ether of a high degree
of purity is not used. When the determinations are made

ORGANIC COMPOUNDS OP PLANTS 205

under uniform conditions, the results are comparable and
are of value when properly interpreted.

Organic Acids
273. Occurrence in Plants.— In all plants and vege-
table foods, there are present bodies known as organic
acids. An organic acid, like all acids, contains hydrogen
which can be replaced by a metal (see Section 75). The
negative radical of the acid contains carbon, hydrogen,
and oxygen. For example, in tartaric acid, H^C^H^Og,
the H2 can be replaced by a metal ; C^HjOg is the tartaric
acid radical. Organic acids, like mineral acids, are
neutralized by bases.

Tartaric Potassium

3,010 trirtr3.t&

2KOH + H^QH^Og = K,C,H A -f 2H,0.
As a rule, the organic acids are not present in a free
state, but are combined with base-forming elements, as
potassium and calcium, forming organic and acid salts.
In plants, the organic acids are found mainly in solution,
as in the sap. When the plant matures, they are used
either for the construction of other organic compounds,
or are neutralized by bases to form insoluble salts, as
calcium oxalate, and deposited as crystals in the leaves.
A small amount of acid is found in all mature seeds, and
during germination, some of the carbohydrates are con-
verted into acids. In green vegetables and small fruits,
the organic acids are found more liberally than in the
seeds of grains ; in the leaves and stems of matured
plants, but little acid is found. Some of the organic
acids from fruits are of commercial value, as crude tar-

2o6 AGRICULTURAL CHEMISTRY

taric acid or argol found in grapes, and from which cream
of tartar is prepared. There are a large number of or-
ganic acids found in plants and food materials, and in the
study of organic chemistry; these acids constitute an im-
portant part. In this work, only a few of the more
common organic acids are considered.

274. Tartaric Acid is the characteristic acid of grapes.
It is also found in small amounts in pineapples, cucum-
bers and potatoes. It can be produced in the laboratory
by the oxidation of milk-sugar and other carbohydrates.
Crude tartar or argol, from which commercial cream of
tartar is made, is deposited when grape juice ferments.
When tartaric acid is neutralized with bases, tartrates
are formed. Sodium potassium tartrate (Rochelle salt)
is one of the most important salts of tartaric acid.

275. Malic Acid occurs in many vegetables and small
fruits, as tomatoes, currants and strawberries. It is the
organic acid which occurs most abundantly in small
fruits. Malic acid can be produced from tartaric acid
by the action of hydrochloric acid.

276. Succinic Acid is found in many plants, and also
in animal tissues. Small amounts of this acid are formed
when dextrose undergoes alcoholic fermentation. Suc-
cinic acid occurs also in soils, particularly those of a
peaty character. It can be produced from malic acid by
the action of hydrochloric acid. Chemically, the three
acids, tartaric, malic and succinic, are closely related.

277. Oxalic Acid is found in small amounts in nearly
all plants, particularly those of the oxalis variety. In

ORGANIC COMPOUNDS OP PI^ANTS 207

some plants, it is present in sufiicient amounts to be
poisonous. Oxalic acid can be produced, in the labo-
rator}^ by the action of nitric acid upon sugar and other
carbohj'drates.

278. Citric Acid is present in lemons and many small
fruits. It is found in small amounts in peas, beans,
vetches, and lupines, and with malic acid in cherries,
strawberries and currants.

Experiment §5. — Citric acid from lemons. Measure out with
the pipette 10 cc. of the prepared lemon juice solution. Dilute
with about 25 cc. distilled water, and add 5 to 7 drops phenolphthal-
ein indicator. Then add standard KOH from the burette until a
faint pink tinge remains permanent. One cc. KOH will neutralize
0.004 gram citric acid. How much citric acid is present ? The
lemon juice solution is prepared by diluting the clear lemon juice
with ten times its bulk of distilled water and filtering.

Questions (i) Why was KOH used in this experiment? (2)
What chemical change took place when KOH was added to the
diluted lemon juice? (3) What change in color was observed?
(4) What was the final product formed in this experiment ? (5)
How does this experiment compare in principle with Experiment 10?

279. Tannic Acid. — In many seeds and leaves of
plants, bitter astringent compounds, as tannin and tannic
acid, are found. They may lessen the value of a food
because they retard the natural process of digestion.
Tannic acid is not present in food plants in any appre-
ciable amounts. Commercially, the tannins are valuable
for the tanning of leather and for other purposes. Tannin-
yielding plants are occasionally grown as marketable
crops.

280. Function and Food Value of the Organic Acids.

208 AGRICULTURAL CHEMISTRY

—The organic acids of plants are valuable mainly because
they impart palatability to foods and exert a favorable
influence upon digestion by stimulating the secretion and
flow of the digestive fluids. Many of the organic acids
have medicinal properties, and some, as oxalic acid, are
poisonous. The organic acids cannot be considered as
heat- or flesh- producing nutrients, but simply as food
adjuncts. In plants, they take an important part in the
assimilation of the mineral elements of plant food, and
the production of new tissue. The acid sap comes in
contact with the soil particles, dissolving the plant food
which is then absorbed by osmosis.

Essential Oils

281. General Properties.— The essential or volatile
oils are the compounds which impart characteristic taste
and odor to plants. They differ from the fixed oils or
fats by completely volatilizing when heated, and leaving
no permanent residue on cloth or paper. They also have
an entirely different chemical composition from the fats.

282. Occurrence. — Volatile or essential soils are found,
in some form, in nearly all plants, particularly during
growth. In some fruits, and seeds, they impart the
characteristic flavor and give individuality to the mate-
rial. Oil of lemon, oil of cedar, and oil of nutmeg are ex-
amples of essential oils. In nearly every plant, one or
more of the essential oils is present at some period of
growth.

283. Chemical Composition and Properties. — The

essential oils are mixed bodies, many of tliem belonging

ORGANIC COMPOUNDS OF PLANTS 209

to the aromatic series of compounds (see Section 138).
According to chemical composition, they may be divided
into four groups, and each group in turn into a number
of subdivisions.

Groups. Examples.

1. Terpenes, CioHjg Oil of lemon, oil of turpentine.

2. Cedrenes, CijH^^ Oil of cedar, oil of cubeb.

3. Aromatic aldehydes. . • Oil of cinnamon, oil of almond.

4. Etherical salts Pineapple and fruit flavors.

The essential oils are separated frortf plants by distil-
lation. At ordinary temperatures, most of them are
liquids, insoluble in water, but soluble in alcohol. When
the terpenes and cedrenes oxidize, they produce resinous
deposits from which turpentine is obtained (see Section
135). The aromatic aldehydes form a homologous .series
beginning with benzoic aldehyde, CgHj.CHO, and are
present in many plants and fruits, imparting flavor.
Ethyl formate, C2H5.HCO2, peach flavor, ethyl butyrate,
CaHj.C^H^O^, pineapple flavor, and amyl valerate found
in apples, are some of the common etherical salts.

284. Essential Oils of Agricultural Crops. — When
hay is cut, the odor produced is due to a volatile oil.
This material is lost when the hay is overcured or ex-
posed to leaching rains. The characteristic odor of
clover, particularly pronounced in sweet clover, is due
to an aromatic body. The odors of all fodder crops are
imparted by characteristic essential oils. In the prepa-
ration of hay and fodder crops, it should be the aim to
prevent, as far as possible, any loss of essential oils.
This can be accomplished by cutting the fodder before it

2IO AGRICULTURAL CHEMISTRY

is overripe, and then avoiding bleaching and leaching.
Rape, turnips, cabbage, parsley and onions contain essen-
tial oils.

285. Synthetic Production of Essential Oils. —

Nearly all of the essential oils found in fruits, as pine-
apple flavor, peach flavor, and vanilla, are capable of
being produced synthetically in the laboratory. They
are definite chemical compounds, and it is only necessary
to bring together, under the right conditions, the radicals
or component parts for them to unite and form these
compounds. Pineapple flavor is ethyl butyrate. The
acid constituent of this salt, butyric acid, is found in stale
butter, while the basic part of the radical is present in
ether and alcohol. The chemical union of butyric
acid and the ethyl radical gives ethyl butyrate or pineapple
flavor. In fact, nearly all of the commercial fruit flavors
are laboratory products. When properly made, they are
identical with the same flavors as found in fruits, but
frequently they contain traces of acid or alkaline products
used in their preparation.

286. Amount of Essential Oils in Plants. — The

amount of essential oils in plants and foods is small, less
than I per cent, and usually only a fraction of a percent.
This small amount is, however, sufficient to give a char-
acteristic taste.

287. Food Value. — Some of the essential oils of fod-
ders, like the organic acids, exert a favorable influence
upon digestion by i^mparting palatability and stimulating
the secretion and flow of the digestive fluids. They are

ORGANIC COMPOUNDS OP PLANTS

211

not heat- or muscle-forming nutrients, but simply food
adjuncts. Some of the essential oils have medicinal
properties, while others, as oil of bitter almonds, are
poisonous. •

Experiment 56. — Essential oil from tea. Place 0.5 gram tea into

Fig. 80. — Preparation of essential oils,
a small flask, and add 50 cc. water. Connect the flask with a
delivery tube, one end of which leads into a test-tube containing

212 AGRICULTURAL CHEMISTRY

water. Arrange apparatus as shown in Fig. So. Apply heat and
distil 3 to 5 cc. Observe odor of distillate which is the volatile oil
of tea. Repeat this experiment, using sweet or red clover.

288. Miscellaneous Compounds of Plants. — Not all

of the non-nitrogenous compounds present in plants are
included in the subdivisions : carbohydrates, fats, organic
acids and essential oils. The most important and more
common ones are, however, included in the above list.
There are a great many others which, for convenience of
classification, are called miscellaneous or mixed com-
pounds.

289. Relationship of Non-Nitrogenous Compounds
of Plants. — A marked general relationship exists between
many of the non-nitrogenous compounds. For example,
the various carbohydrates are capable of undergoing
chemical changes in which one form is changed to
another. Starch can be converted into cellulose, sucrose,
maltose or any other carbohydrate, and conversely cellu-
lose can be converted into starch or other similar com-
pounds. These changes take place during plant growth,
particularly in the germination of the seed, and are
brought about by the action of ferment bodies which
cause either the addition or elimination of water from the
molecule, as

2C,H,A+H,0 = C,,H,Ai-
Not all of these reactions can take place in the laboratory.
Starch may be changed to glucose or maltose, and sucrose
may undergo inversion and form invert sugars, but
sucrose cannot be made in the laboratory ; neither can
starch or cellulose be made from glucose. During

ORGANIC COMPOUNDS OF PLANTS 213

germination, some of the carbohydrates are converted
into organic acids.

The fatty acids are the characteristic constituents of
fats. In germinating seeds, fat is formed from starch by
the addition of oxygen. The pectose substances are
capable of being separated in the laboratory into glucose
and acid products. Likewise the glucosides may be split
up into glucose and acid bodies. In fact, the various non-
nitrogenous compounds of plants, considered as a whole,
are more or less related in chemical composition.

290. Food Value of the Non-Nitrogenous Com=
pounds. — As a class, the non-nitrogenous compounds
are valuable as heat- and energy-producing nutrients.
They do not all have the same caloric or fuel value ; for
example, a gram of starch yields 4.2 calories while a gram
of fat yields 9.2. As a rule, the more concentrated the
compound is in carbon, the greater is its fuel value. When
properly associated and combined with the nitrogenous
compounds, the non-nitrogenous nutrients of plants may
produce fat in the animal body. A few of the non-
nitrogenous compounds, as the essential oils, have but
little direct value as nutrients. Others, as some bitter
principles and tannic compounds, may lessen the value of
foods or impart a negative value. The carbohydrates,
fats, and related non-nitrogenous compounds take an im-
portant part in the nutrition of man and animals, and
many foods owe their value entirely to the fats and car-
bohydrates which they contain.

CHAPTER XXIV
Nitrogenous Organic Compounds of Plants

291. Amount of Nitrogenous Matter in Plants

As a rule, less than 15 per cent, of the dry matter of
plants is nitrogenous material. In the seeds of legumes,
as beans and peas, this amounts to about 22 per cent. In
nearly all plants, the non-nitrogenous compounds are
from six to ten times more abundant than the nitrogenous.

292. Different Terms Applied to Nitrogenous Com-
pounds.— Unfortunately, the various terms used to desig-
nate the nitrogenous compounds have not been uniformly
applied. The terms nitrogenous compounds, proteids,
crude protein, and albuminoids have been used synony-
mously, but each applies to a different class of bodies.
The terms organic nitrogenous compounds and crude
protein are the most satisfactory when applied to the
entire group ; proteids and albuminoids are subdivisions
of the nitrogenous compounds.

293. Complexity of Composition. — The nitrogenous
compounds are more complex in composition than the
non-nitrogenous. The percentage composition and for-
mulas of nearly all of the non-nitrogenous compounds of
plants have been determined, and while the percentage
composition and the physical and chemical properties of
the more important nitrogenous compounds are known
no definite formulas have, as j'et, been applied because of
the complexity of their molecular structure. The nitroge-

NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 215

nous compounds are composed of carbon, hydrogen,
nitrogen, and oxygen, and many contain in addition to
these, phosphorus, sulphur and other elements.

. 294. Classification of Nitrogenous Compounds. —

For food purposes, the nitrogenous compounds of plant
and animal bodies may be divided into four groups : ( i )
Proteids, (2) albuminoids, (3) amides, and (4) alka-
loids. There are a few nitrogenous compounds in plants
that do not find a place in any of the above subdivisions.

Proteids

295. General Composition.— Proteids are complex
nitrogenous compounds that contain about 16 per cent, of
nitrogen and less than 2 per cent, of sulfur. The per
cent, of the different elements in protein compounds from
various sources ranges as follows :

Per cent.

Carbon 51.2-54.7

Hydrogen 6. 7-7.6

Nitrogen 15. 2-18.0

Oxygen 20. 2-23.5

Sulfur 0.3-2.0

It was believed, at one time, that all of the various
compounds called proteids had, in common, a nitrogenous
radical in their molecule to which the name protein was
given, but this hypothesis has not been found correct.
The term protein has been retained but without reference
to the supposed protein radical.

296. Occurrence. — Proteids are found more abun-
dantly in the seeds of plants than in the leaves or other
parts, and are always present in the active living cells of

2l6 AGRICULTURAL CHEMISTRY

both plants and animals. The proteids take an important
part in life processes, protoplasm being largely of a
proteid nature. In the growing plant, the proteids are
found most abundantly in the leaves ; at maturity, they
are stored up in the seed for the future use of the embryo.
The proteids occur either in a soluble form in the liquids
of plant and animal tissues or in a semisolid, insoluble
condition as a part of the tissues. The proteids from
animal and plant sources are closely related, but are not
in every respect identical. For food purposes, however,
they may be jointly considered.

297. Physical Properties. — While the members of
the proteid group differ materially, they all have certain
physical properties in common. All are optically active
and turn polarized light to the left. The soluble proteids,
with the exception of peptones and proteoses, are coagu-
lated by heat. The proteids show a wide range in solu-
bility, but all are soluble in either acid or alkaline solu-
tions. As a class, they do not crystallize, and are
diffusible with the exception of the peptones and pro-
teoses.

298. Chemical Properties. — In structure the proteid
molecule is an exceedingly complex and unstable bod3\ It
is readily acted upon by ferments and chemicals. Nitro-
gen seems to form a weak link in the chain of elements.
Proteids unite with acids and alkalies to form acid and
alkali proteids. In plants, the proteids are generally united
with small amounts of organic acids and mineral com-
pounds, particularly phosphorus and potassium. They
all respond to certain reactions : ( i ) Nitric acid gives a

NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 217

permanent yellow color ; (2) a solution of mercury and
nitric acid, known as Millon's reagent, gives a brick-red
color with the acid if heated ; (3) a solution of copper
sulfate and potassium hydrate gives a violet-colored solu-
tion. The proteids, found in living cells, have different
properties from those in dead tissue. Proteids readily
undergo oxidation, and are chemically altered in the
preparation of many foods. When the protein molecule
is acted upon by heat, a large number of products are
formed, as fatty acids, amides, aromatic bodies, ammonia,
and carbohydrate-like bodies. The most common change
which the proteids undergo is the rearrangement of the
atoms and radicals in the molecule. The coagulation
of albumin by heat is a chemical reaction in which the
atoms and radicals in the albumin molecule are sim-
ply rearranged structurally. The fact that it is possi-
ble for such a large class of compounds as the proteids
to be composed of only a few common elements, and
for the various members to have different properties,
is accounted for by differences instructural composi-
tion.

Experiment ^y . — Testing for nitrogenous organic compounds.
Mix 0.5 gram dry clover with enough soda lime to half fill a test-
tube. Connect the test-tube with a delivery tube, one end of
which leads into another test-tube containing water. Apply heat
for from five to seven minutes. Test the distillate with test paper.
(Soda lime has the power to decompose proteid material and
liberate the N as NH3. The C and O of the proteid unite and form
COjandH^O.)

Questions. ( i ) What reaction was obtained when the distillate
was tested with litmus ? (2) What compound was produced which

2l8 AGRICULTURAL CHEMISTRY

gave this reaction? (3) What does this indicate that clover con-
tains? (4) Why was this compound liberated?

299. Classification of Proteids. — For purposes of
study, the proteids may be divided into five classes : (i)
Albumins, (2) globulins, (3) albuminates (casein), (4)
peptones and proteoses, and (5) insoluble proteids.

There are some proteids that do not belong to any of
the above divisions. The albumin, albuminate (casein),
and the insoluble proteids are those found most abun-
dantly in plant and animal bodies.

300. Albumins. — The albumins are proteids soluble
in water and easily coagulated by heat. Egg albumin,
serum albumin and lactalbumin, are examples of animal
albumins. Wheat, oats, rye and nearly all vegetables,
when extracted with water, yield some albumin which
can be coagulated by heat or precipitation with chemicals.
In many vegetables, the albumin is lost when the mate-
rial is soaked in water for any length of time. Potatoes,
for example, lose a large amount of their albumin if
soaked in cold water before boiling.

Experiment 58. — Tests for albumin . In each of four separate test-
tubes, place a 3 cc. portion of a solution of egg albumin. To No. i
add 3 cc. strong alcohol. To No. 2, add 2 cc. HNO3 and heat ;
when cool, add NH^OH. To No. 3, apply heat. To No. 4, add a
few drops of lead acetate.

Questions, (i) What change occurred when the solution was
heated? (2) When alcohol was added? (3) When HNO3 was
used and heat applied ? (4) What did the Pb(C2H302)2 do? (5)
What do these tests show in regard to the properties of albumin.

Experiment sg. — Albumin and allied proteids from oats. Place
in a flask 10 grams of ground oats and 50 cc. of water. Cork and

NITROGKNOUS ORGANIC COMPOUNDS OF PI.ANTS 219

shake vigorously ; let stand for half an hour or until the next day.
Filter (if not clear refilter) and make the following tests with
separate portions of the filtrate. ( i ) To 5 cc. add a few drops of
tannic acid. (2) To 5 cc. add a few drops of lead acetate.

Questions. ( i ) What were the results when tannic acid and lead
acetate were added ? ( 2 ) Do the tests indicate any large amount
of albumin ? (3) How do these tests compare with those of the
preceding experiment ?

301. Globulins form a group of proteids insoluble in
water, but soluble in dilute salt solution. When animal
or vegetable substances, as meat, eggs, wheat, rye or oats,
are treated with dilute salt solutions (NaCl), after re-
moval of the albumins, soluble proteid substances called
globulins are obtained which are coagulated by heat.
There are a large number of vegetable globulins. The
chief globulin of meat is myosin. When meat is soaked
in a dilute salt solution, and then cooked as food, the
myosin is extracted and lost. In strong salt solution,
myosin and other globulins are insoluble ; hence the use
of strong brine in the curing of meats. In the blood,
there are globulins present, and in the yolk of an egg, a
globulin-like body, vitellin is found. As a rule, globulins
do not make up a very large proportion of the proteids of
foods.

Experiment 60. — Obtaining globulin from oats. To the residue
left in the flask from Experiment 59, add 2 grams of salt and 50 cc.
water. Shake vigorously and, after one hour, filter and make the
same tests as in Experiment 59. Save the residue in the flask for
Experiment 65.

Questions. ( i ) What results were obtained when the solution
was tested with lead acetate and tannic acid,? (2) What do these
results indicate ? (3) What are globulins ?

2 20 AGRICULTURAL CHEMISTRY

Experiment 6i . — Separation of meat globulin or myosin. Test
as follows four 3 cc. portionsof myosin solution, prepared by soaking
fresh meat in a 5 per cent, salt solution. To the first, add a few
drops of alum solution. To the second, add a few drops of lead
acetate. To the third, add salt until the solution is saturated.
To the fourth, apply heat.

Questions. ( i ) What result was obtained with the alum solution
and what does this indicate ? (2) What did the lead acetate and
the salt solutions do? (3) What was used as the solvent for the
myosin? (4) What is myosin? (5) What are the properties of
myosin ?

302. Albuminates. — The albuminates are a group of
proteids widely distributed in both animals and plants.
They may be produced by the action of either dilute acids
or alkalies upon albumins or globulins. The albuminates
are insoluble in water, and when an acid albumin is
netitralized with an alkali, the albuminate is precipitated.
In like manner, an acid precipitates an alkali albumin.
Casein is an albuminate present in milk, and is in a semi-
soluble form combined with some of the mineral matter.
Casein is soluble in dilute alkalies, but is precipitated by
acids. In plants the albuminates are sometimes called
vegetable casein. From peas, a casein-like body can be
extracted.

E'^periment 62. — Separation of meat albuminate or syntonin. To

3 cc. portionsof prepared syntonin soh;ti on, add: To the first, Na^COj
until neutral, avoiding excess as it dissolves the precipitate ; to the
second, add NaOH a drop at a time until neutral ; to the third, add
a few drops of lead acetate. Syntonin solution is prepared by cutting
fresh meat into small pieces, and extracting it for four hours, in
water containing a few drops of HCl.

Questions, (i) What result was obtained when each reagent

NITROGENOUS ORGANIC COMPOUNDS OF PI ANTS 221

was added to the syntonin solution? (2) What was used in the
preparation and what as the solvent for syntonin. (3) What is
syntonin ? (4) What are the properties of syntonin?

Experiment dj. — Preparation of vegetable casein from peas.
Place in an evaporator, i gram of pea meal, 100 cc. H2O, and 3 cc.
NaOH. Heat on the sand-bath, occasionally stirring. Filter. If
the filtration is slow, pour off and use some of the clear solution.
Neutralize with HCl and observe.

Questions. — ( i ) To what class of proteids does vegetable casein be-
long? (2) What was used as the solvent for extracting the vegetable
casein? (3) What effect had HCl? (4) How does vegetable
casein resemble that from milk in solubility and other properties ?

303. Peptones and Proteoses are closely related
groups of proteids present in animal and vegetable bodies.
When any proteid material is acted upon by the peptic
and tryptic ferments, peptones are formed. These are
soluble in water, and are not coagulated by heat or
precipitated by acids or alkalies. They are derived from
other proteids by ferment action, and are the first prod-
ucts formed when the proteids of the food undergo diges-
tion. In prepared or peptonized foods, the peptonizing
process is carried on artificially. When meat undergoes
the curing or ripening process, a small amount of peptones
is produced. Peptones are naturally present in milk and
also in traces in nearly all cereal products. When seeds
germinate, proteoses are formed. These compounds are
never present in ordinary foods in any appreciable amount.

Experiment 6^. — Tests with peptones. Measure into separate
test-tubes, three 5 cc. portions of peptone solution. To the first,
apply heat and, when cool, add a few drops of tannic acid. To the
second, add a few drops of alum solution. To the third, add 5 cc.
alcohol. The peptone solution is prepared by treating coagulated

22 2 AGRICULTURAL CHEMISTRY

egg albumin with pepsin. 5 grams of commercial pepsin are dis-
solved in I liter of water containing 5 drops HCl. This artificial
pepsin solution represents the solvent power of gastric juice upon
proteid substances. The white of a hard boiled egg is put into a
flask, and 250 cc. pepsin solution added ; the flask is then placed in
a water-bath which is kept at a temperature of 38° C. for four or
five hours.

Questions, (i) What action did the pepsin have on the egg
albumin and what was produced ? (2) What was the result, when
heat was applied in test No. i, and how does this compare with the
result when egg albumin was similarly treated ? (3) What effect
did tannic acid and alum have upon the pepsin solution and what
did they produce? (4) What was the result when alcohol was
added? (5) What are peptones? (6) What does this experiment
show in regard to some of the properties of peptones ?

304. Insoluble Proteids. — The in.soluble proteids are
present in plant and animal bodies in larger amounts
than are any of the other proteids, and include a large
number of similar though chemically distinct bodies.
Muscular tissue is composed largely of insoluble proteids.
In seeds, the term gluten is frequently applied to this
class of compounds which is a mixture of two or more
insoluble proteids. Wheat gluten for example is com-
posed of gliadin and glutenin. Gliadin is a glue-like body
which binds together the flour particles, and in bread-
making, enables the gas to be retained in the dough.
Glutenin is a fine, gray material which unites mechanically
with the gliadin to form gluten. An excess of gliadin
produces a soft gluten.

As a class, the insoluble proteids are not soluble in
water or dilute salt solutions, but are soluble in dilute
acids and alkalies. They all undergo the peptonizing

NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 223

process and yield proteoses and peptones. The insoluble
proteids are the most common form of proteids in foods.

Experiment 6j. — Obtaining insoluble proteids from oats. To
the residue left in the flask from Experiment 60, add 2 cc. NaOH
and 50 cc. water. After shaking and allowing half an hour (or
until the next day) for the extraction of the proteids, filter off the
solution and make the following tests: (i) Neutralize 5 cc. with
HCl, and if no precipitate appears, add a few drops of lead acetate;

(2) neutralize 5 cc. with HCl and evaporate to dryness on the
water-bath.

Questions, (i) Why was NaOH used? (2) What effect did the
HCl and lead acetate have when added to the solution, and what
was formed? (3) How did this precipitate of insoluble proteids
from oats compare in amount with the globulin and albumin
precipitation in Experiments 59 and 60 ? (4) What is an insoluble
proteid ?

305. Food Value of Proteids.— The proteid com-
pounds of plant and animal bodies serve three purposes
as nutrients : ( i ) To produce new muscular tissue and
vital fluids in the body, and supply material for repairing
broken-down tissue ; (2) to produce heat and energy;

(3) to assist in the production of fat.

The main function of the proteids is to produce new
proteid tissue in the body, and to furnish a material for
the repair of old or worn-out proteid matter. The vital
fluids of the body, as blood, chjane, milk, and the diges-
tive fluids, all contain proteids, and the animal body is
incapable of producing any from either non-nitrogenous
or amide compounds. When the food fails to supply a
sufficient amount of protein, the body uses its reserve
supply as long as it lasts, and then starvation results.
When there is an excess of proteids in the food, it is

224 AGRICULTURAL CHEMISTRY

used for producing heat or is stored up in the body as
fat. Either an excessive or a scant amount of proteidsin
a human or animal ration is not desirable or economical.
As stated under chemical properties of proteids, Section
298, the proteid molecule, when broken up, forms a large
number of simpler bodies, as fatty acids and carbohydrate
radicals ; hence, it is poor economy to feed proteids in
excess and have part perform the functions of fats and
carbohydrates. Protein is present in many foods in defi-
cient amounts, and when such foods are used, they should
be combined with those rich in proteids. There are a
few proteids which are poisonous bodies. Some of the
toxins produced during disease are proteids.

306. The Amount of Proteids in Plants varies accord-
ing to the kind, stage of growth, and part of the plant
considered. Seeds always contain the largest amount,
while roots and stalks contain the least. In wheat, oats,
barley and rye, the amount ranges from 10 to 15 per cent. ,
while in corn, it ranges from 9 to 12 percent. Beans
and peas contain about 25 per cent. Clover hay contains
from II to 14 per cent. ; timothy hay and corn fodder,
6 to 9 per cent. ; while in straw there is usually less than
4 per cent. During the early stages of growth, the dry
matter in all plants is relatively richer in proteids than at
maturity. This is because the proteids are formed mainty
in the early stages, while the carbohydrates are produced
more abundantly in the later stages of growth.

307. Crude Protein.— This term is applied to the nitroge-
nous compounds of foods, taken collectively, as a group.
The word crude is used to distinguish this group because

NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 225

it contains various nitrogenous bodies, not proteids.
Pure protein is a simple chemical compound, while crude
protein consists of a group of compounds of which pure
protein is one. The albumin of eggs and milk and the
gluten of grains are types of
pure proteids. In many foods,
as potatoes, roots, and fruits,
less than half of the crude pro-
tein is pure protein. Crude pro-
tein, from different sources, is
unlike in character, composition,
and, to a certain extent, in food
value. Less is known of its
composition and food value than
of any other class of nutrients
in foods.

In the analysis of plant and
animal substances, the chemist
first determines the per cent, of
total organic nitrogen and then
multiplies this by 6.25 to obtain
the equivalent amount of crude
protein. This is because the
proteids contain, on the average, nitrogen.
about 16 per cent, nitrogen, or there is about one part of
nitrogen to every 6.25 of protein (100 h- 16 ^ 6.25).
The nitrogen can be determined with accuracy ; in fact,
the method for its determination is one of the most accu-
rate in chemistry. In brief, the method consists in first
digesting a small weighed amount of material in a flask

15

Fig. 81. — Digestion apparatus
used in the determination of

226

AGRICULTURAI, CHEMISTRY

with sulfuric acid to oxidize the organic matter and con-
vert the nitrogen into ammonium sulfate (see Fig. 8i).

Fig. 82. — Distillation apparatus used in the determination of nitrogen.

The nitrogen, in the form of ammonium sulfate, is then
liberated as free ammonia, distilled and its amount deter-
mined (see Fig. 82).

Albuminoids

308. Composition of Albuminoids. — This term is
applied to a class of bodies resembling proteids, but
differing from them in composition and food value.
Albuminoids are found in both animal and plant bodies,
but more abundantly in animal tissues. Some albumi-
noids are composed of carbon, hydrogen, nitrogen, and
oxygen, while others contain, in addition, phosphorus,
sulfur and other elements.

309. Nuclein is an albuminoid found in both plant
and animal bodies ; it is the material of which the nuclei
of cells are composed, and has been separated from milk,
the yolk of egg, and white blood corpuscles, as well as

NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 227

from plant substances. This albuminoid contains phos-
phorus, and has been assigned the formula CjoH^gNgPjO^a.
Nuclein takes an important part in the growth and life
processes of both plant and animal cells. From different
sources it has slightly different chemical properties. It
is probably a mixture of several bodies, and not a dis-
tinct chemical compound.

310. Gelatin is an albuminoid obtai-ned from connec-
tive tissue and bones by the action of either boiling
water or dilute acids upon an albuminoid called collagen.
Commercial gelatin or glue is the crude product obtained
from animal refuse. The formula CioaHi^jN^^Ogg has been
assigned to gelatin. Gelatin contains no sulfur, and has
a different proportion of nitrogen from that found in
proteid bodies.

311. Mucin is an albuminoid present in connective
tissue. It is the chief constituent of mucus, and imparts
sliminess to the secretions of the mucous membrane.
Mucin is present in the saliva from the submaxillary
glands, and in the bile and other fluids of the body, par-
ticularly those of an alkaline nature.

312. Elastin is an insoluble albumoid found in connec-
tive tissue. Keratin is the hard, horny material found
in nails, hoofs and horns, while chondrin is obtained from
cartilage. A number of other albuminoids also are pres-
ent in both animal and plant bodies.

313. Food Value of Albuminoids. — Gelatin and
most of the animal albuminoids undergo digestion, but
cannot take the place of protein in a ration. An animal

228 AGRICULTURAIv CHEMISTRY

would soon die if its nitrogenous food were entirely in
the form of gelatin. Gelatin, when combined with other
nutrients, may, however, prevent the rapid conversion of
the tissue proteids into circulatory proteids, and thus
aids in establishing a proteid equilibrium in the body.
Nuclein and some of the nucleated albuminoids have a
higher food value than gelatin, and are considered as
having the same value as the true proteids. As a
nutrient, the gelatin albuminoids conserve the proteids
of the body, but do not take the place of proteids in the
repair of worn-out tissues.

Amides and Amines
314. Composition and Properties. — The amides and
amines are heterogeneous compounds found in both
animal and plant bodies. They are less complex in com-
position than either the proteids or albuminoids; and are
produced by replacing one or more of the hydrogen atoms
of ammonia with an organic radical. If the radical is
acid in character, an amide is formed ; if alcoholic or
basic, an amine is produced. Amides and amines are re-
lated to ammonia as will be observed from the following
formulas :

yH yCjH^Oj /CH3

N— H X— H N— H

Ammonia. Amide. Amine.

(Amidoacetic acid. ) (Methylamine. )

When the methyl group or radical replaces one of the
h3^drogen atoms of NH3, the product is methylamine.
When the acetic acid radical replaces one of the hydrogen

NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 229

atoms of NH3, the product is amidoacetic acid. The
amides and amines are sometimes called compound am-
monias, and are produced in plants from ammonia during
growth, and in animals during the digestion of proteids.

315. Formation and Occurrence in Plants. — The
amide and amine compounds in plants are present mainly
in the early stages of growth. The young plant takes
up from the soil simple nitrogenous compounds, as am-
monia, then a chemical change occurs in the tissues of
the plant, and as a result, a part or all of the hydrogen
of the ammonia is replaced, and an amide is formed. In
the study of the composition of proteids (see Section 295)
it was stated that the proteid molecule when decomposed
yields amide and amine products; consequently it would
appear that these compounds are intermediate products
in the production of proteids. In the early stages of
plant growth, amides are present in greatest abun-
dance, but as the plant approaches maturity, they are
used for the production of proteids. In clover, for
example, 35 per cent, of .the total nitrogen is in the form
of amides before bloom, while only 12 per cent, is in the
same form after bloom.

316. Formation and Occurrence of Amides in Ani=
mats. — In the animal body, amides and amines are not
formed from ammonium compounds, as in plants, but
from proteids. When the proteid molecule is broken up,
as in digestion, amides and amines are produced. Urea,
an amide, is one of the final products in the digestion of
protein, and is excreted from the body in the liquid ex-
crements, while amidoacetic acid is excreted with the

230 AGRICULTURAL CHEMISTRY

solid excrements. The animal body cannot produce
proteids from amides, or amides from ammonia. This
elaboration or construction process can take place onlj^ in
the plant. The animal body can simply make over into
other forms, the proteids supplied in the food, or decom-
pose them and form amides and other products.

In animal tissues, many amides are produced during
fermentation and decay, as methylamine, the base which
gives the characteristic odor of fish. Methylamine is also
found in rye fodder when the plant is at the heading-out
stage, and imparts a fishy taste to the milk of cows fed
upon such fodder. In meats, these compounds are
associated with other bodies, as ptomaines, w^hich are of
a poisonous nature. Amides are also produced during
the digestion of food, and if the intermediate products
between proteids and amides are not completely oxidized,
poisonous substances are formed.

317. Food Value of Amides. — The amides do not
have a high food value compared with the proteids, and
cannot replace proteids in a ration. The amides possess
only a secondary food value, and, like the gelatin albu-
minoids, may to a limited extent prevent a rapid waste of
body tissue. Some give taste and character to foods, as
asparagin in asparagus, and in meats they are the bodies
which give flavor. Some of the amides have medicinal
properties, while others are poisonous.

318. Amount of Amides in Foods. — In matured
grains, less than 5 per cent, of the total nitrogenous
matter is in the form of amides, and in meats there is
less than i per cent. In some foods, notably roots and

NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 23 1

tubers, the amides constitute a third or more of the nitroge-
nous matter. In fodders, the amount depends upon
the stage of growth at which the crop is cut. "When
mature, from 10 to 15 per cent, of the nitrogenous matter
is in the form of amides, while in the early stages of
growth, there are two or three times as much. The
amides and amines form a part of crude protein (see
Section 307). In comparing the crude protein content
of food, the amount of amide nitrogen should be con-
sidered, because the amides are of less food value than
the proteids.

319. Protein Production and Disintegration. — The

following cycle of changes takes place in the production
of proteids in plants :

(i) Ammonia is taken from the soil.

(2) An amide is produced from ammonia.

(3) A proteid is finally formed from the amide.
When plants are used as food, the reverse order of

changes takes place in the animal body :

(i) The proteid of the food undergoes digestion, and
is made over into proteid tissue in the body. This pro-
teid tissue is finally broken up into amides.

(2) The amide is expelled from the body as waste
matter.

(3) In the soil, the amides are changed to ammonia,
and are then ready to begin anew this cycle of changes.

Alkaloids

320. General Composition. — The alkaloids are nitroge-
nous organic compounds present in many animal and

232 AGRICUI^TURAI^ CHEMISTRY

plant bodies, but not found in any appreciable amount in
food plants. They are basic in character and unite with
acids to form salts, just as ammonia unites with acids
to form salts. Quinin, for example, in an alkaloid, and
with sulfuric acid yields quinin sulfate. Animal alka-
loids are sometimes called ptomaines and leucomaines.
The vegetable alkaloids are generally named from the
species of plant or source from which they are obtained,
as Peruvian bark alkaloids, lupine alkaloids, and opium
alkaloids.

321. Plant Alkaloids. — No alkaloids are found in
cereals or ordinary food plants, though at one time it
was supposed that oats contained such a stimulating
body to which the name avenin was given; later investi-
gations have shown that there is no avenin or alkaloidal
body in oats. The alkaloids chemically are closel}^
related to the amines, and are produced by the action of
amido compounds upon other bodies. They are also
produced by the action of fungus bodies, as eargotin, the
alkaloid from eargot or grain smut. While found most
abundantly in the leaves and seeds, they are found in all
parts of plants. Some are cultivated for these bodies
which possess medicinal properties. Many poisonous
weeds contain alkaloids as the water hemlock and
monk's hood. Large numbers of alkaloids are known,
and since they possess medicinal rather than food value,
they are of more importance to the medical and pharma-
ceutical than,- to the agricultural student. A few of the
more common alkaloids and their sources are :

Piperine, from seeds of black pepper.

NITROGENOUS ORGANIC COMPOUNDS OF PIvANTS 233

Sinapore, from seeds of mustard.
Vicine, from seeds of vetch.
Nicotin, from leaves of tobacco.
Quinin, from peruvian bark.
Strychnin, from strychnos bean.
Brucine, from strychnos bean.
Morphin, from opium (seeds of poppy).
Lupinin, from lupin seeds.

323. Animal Alkaloids. — In the animal body alka-
loids are produced by ferment action. During disease,
and when the proteids of the food fail too undergo the
natural chemical changes of digestion, alkaloids, or
ptomaines, are produced which are active poisons or toxic
bodies. When animal tissue undergoes decay, ptomaines
are produced as the result of ferment action. In stale
meat, fish, and cheese, there are a number of such bodies.

323. Food Value and Production. — The alkaloids
cannot be regarded as nutrients as they possess no direct
food value. Medicinally, many are valuable because of
their action upon certain nerve centers. Some alkaloids
lessen the value of foods because they prevent the nor-
mal process of digestion. A few alkaloids have been
produced in the laboratory by synthetic methods, and it
is believed that in a short time all of the more important
ones will be produced in this way.

324. Mixed Nitrogenous Compounds. — There are a
few nitrogenous organic compounds present in foods
which do not belong to any of the four divisions : Proteids,
albuminoids, amides, and alkaloids. Such bodies are called

234 AGRICULTURAL CHEMISTRY

mixed nitrogenous compounds, and are closely related to
both the nitrogenous and non-nitrogenous groups.

325. Lecithin is a nitrogenous fat. It is soluble in
ether, and has many of the characteristics of fats. It
contains fatt)^ acids in combination with nitrogenous bases
and other bodies. It is present in milk, egg-yolk, and in
small amounts in all of the cereals.

326. Nitrogenous Qlucosides. — There are a number
of glucosides which contain nitrogenous radicals. These
glucosides, when treated with acids, yield glucose and
nitrogenous acid products. The nitrogenous glucosides
and lecithin may be regarded as compounds which are
intermediate in the classification of the organic com-
pounds into nitrogenous and non-nitrogenous groups.

327. General Relationship of the Nitrogenous Or-
ganic Compounds. — A general relationship exists among
the nitrogenous compounds similar to that among
the non-nitrogenous (see Section 289). The amides and
amines are the simplest in chemical structure of the
nitrogenous compounds, while the proteids are the most
complex. In plants, the amides are intermediate com-
pounds formed in the production of proteids. The proteid
molecule contains, with other bodies, amide and fatty acid
radicals. Amide products are also obtained from the
albuminoids. Thus it appears that the amides and amines
form the basal structure of the nitrogenous part of the
molecules of proteids, albuminoids, and alkaloids, and
these compounds differ from each other chemically,
according to the nature and kind of radicals in combi-
nation with the different amide and amine compounds.

CHAPTER XXV
Chemistry of Plant Growth

328. Seeds. — A seed is an embryo plant surrounded
by reserve food materials in the form of mineral matter
and nitrogenous and non-nitrogenous compounds.

329. Ash of Seeds. — The proportion of ash in seeds is
small compared with that in other parts of plants. For
example, the wheat kernel contains 2 per cent, and
the straw 7 per cent.; corn contains 1.75 per cent, and
the stalks 7 per cent. While seeds contain comparatively
little ash, this ash is more concentrated in the essential
elements than that of the other parts of plants. In the
seeds are stored large amounts of phosphorus pentoxid,
magnesia and potash ( ash elements which are of most im-
portance for the nutrition of the young plant), while in
the straw are found the largest amounts of the non-
essential mineral elements, as silicon, sodium and chlorin.
The per cent, of the various ash elements in cereals and
other seeds is given in Section 209. The amount of ash
in seeds is quite constant, more so than in the stems,
leaves or other parts of plants. In mature wheat, there
is rarely more than 2. 10 per cent, or less than 1.80 per
cent. , while in the straw, the amount may range from 5 to
9 per cent. Constancy of composition is a characteristic
of the ash of seeds.

330. Non-Nitrogenous Compounds of Seeds. — Starch,
cellulose, and fat are usually the most abundant non-
nitrogenous compounds in seeds. Small amounts of

236 AGRICULTURAL CHEMISTRY

other non-nitrogenous bodies, as sugar, gums, pentosans
and organic acids, are also present. There is no regular
law as to the way in which the reser\^e food is stored up
in seeds. Even in the same family of plants, the nature
of this reserve food may vary between wide limits.
Starch forms the largest proportion of the reserve food of
the cereals. In oil seeds, as flax, rape and mustard, fat
is the main form of non- nitrogenous food. Since fat is
about 2.25 times more concentrated in fuel value than
starch, it follows that in oil seeds, a large amount of re-
serve material is stored up in a small space. Oil seeds
are, as a rule, small in size, but concentrated in both non-
nitrogenous and nitrogenous food. The cellular tissue of
seeds is composed of cellulose and pentosan materials.
The amount of pure cellulose is generally small.

331. Nitrogenous Compounds of Seeds. — The nitroge-
nous compounds of seeds are present mainly in the
form of insoluble proteids, as the glutens of the cereals.
Small amounts of other proteids, as albumin, globulin and
proteose, are also present, as well as some of the albumi-
noids, as nuclein, and a small amount of amide com-
pounds. In studying the carbohydrates, it was found
that starch was present in regular organized forms called
starch granules. In many seeds, particularly cereals, the
proteids also are present in organized forms called
aleurone grains. Under the microscope, the aleurone
grains look like crystals. They are not true crystals
because they are not built on a definite plan. An
aleurone grain consists mostl}^ of proteid matter enclosed
in a nitrogenous envelope. The nitrogenous compounds

CHKMISTRY OF PLANT GROWTH 237

of seeds are stored up mainly in the germ or portion adja-
cent to the embryo. The amount of nitrogenous mate-
rial in seeds is, like the ash, quite constant in form and
amount.

332. Chemical Changes during Germination. — All
of the food materials in seeds undergo chemical
changes during the process of germination. The chief
agents in bringing about these changes are the various
kinds of soluble ferments hich are always present win
seeds. The more important changes can be summarized
as follows : Cellulose is changed to soluble carbohydrates;
starch is changed to soluble forms and then into dextrose
bodies ; fat is changed to starch ; insoluble proteids are
changed to proteoses and a small amount to amides.
Organic acids are produced from both nitrogenous and
non-nitrogenous compounds during germination.

333. Change of Starch to Soluble Forms. — When
seeds germinate, the starch is changed to soluble forms
before it is utilized by the plantlet. During conversion
of starch into soluble forms, the diastase ferment be-
comes active, rendering the granulose soluble, and finally
leaving nothing but a pitted cellulose skeleton which is
also rendered soluble. The change of starch into soluble
forms and dextrose bodies is brought about by the action
of ferments, particularly diastase which is found in all
seeds. During the process of germination, some of the
starch is oxidized, and heat is produced. Not only
starch, but other carbohydrates, as pentose and cellulose,
likewise undergo similar change during germination.

Experiment 66. — Reaction of germinating seeds. Fill a cylin-

238

AGRICULTURAL CHEMISTRY

Fig. 83.

der with moist sawdust; then place upon
the sawdust between two blue litmus papers
a few wheat seeds. Cover with a little of
the moist sawdust. After germination, ex-
amine the litmus paper.

Questions. ( i ) What was the reaction of
the rootlets upon the litmus paper? (2)
How was the material which caused the re-
action produced? (3) What does this sug-
gest as to the solvent action of plant roots?
(4) How would the dry matter of the ger-
minated seeds compare with that of the origi-
nal seeds ?

334. Change of Fats to Starch. —

In germination, the fats are first broken
up into fatty acids and then con-
verted into starch, soluble carbohydrates as dextrin and
invert sugars. It is estimated that 887 parts of fat will
produce 1700 parts of starch by the simple addition of
oxygen from the air. Ferment action causes this change
to take place. In the oil seeds, about twice the amount
of reserve food is stored in the same space in the form of
fat as in other seeds in the form of starch.

335. Change of Insoluble Proteids to Soluble Forms.

— The proteid compounds of seeds, present mainly in
insoluble forms, are converted by ferment action into
soluble forms as proteoses. Some of the soluble pro-
teids are broken down into amides which are then in con-
dition to be transported through the plant tissues and
used as building material. After passing through the cell
walls, these compounds are reconstructed into proteids.

CHKMISTRY OP PI^ANT GROWTH 239

There is always a slight loss of nitrogen in the germina-
tion of seeds.

336. Germination of Seeds and Digestion of Food
Compared. — The chemical changes which take place in
the germination of seeds are similar to those which take
place in the digestion of food. In the germination pro-
cess, starch, fat, . and proteids are changed by ferment
action to soluble forms. The diastase and peptonizing
ferments are among the most active in producing
the chemical changes in both the germination and diges-
tion processes. Seed germination is, in part, a digestion
process.

337. The Necessary Conditions for Germination

are: (i) Moisture, (2) heat, and (3) oxygen. The
same conditions which produce decay are necessary for
germination. The temperature required for germination
ranges between comparatively narrow limits :

Wheat 35° F. to 104° F.

Barley 38° F. to 104° F.

Peas 44.5° F. to 102° F.

Corn 48° F. toii5°F.

The necessity of oxygen for germination is shown by
the following experiment : When seeds are put into
water those that float are generally the only ones that
germinate. A few of those that sink may germinate,
getting their oxygen from that dissolved in water. If a
current of air is passed through the water all of the seeds
will germinate. Oxygen is necessary during germination
in order to oxidize some of the reserve material and pro-
duce heat. Seeds, in germinating, always lose weight.

240 AGRICULTURAL CHEMISTRY

Malted or germinated seeds weigh less than the original
seeds.

338. Heavy= and Light=Weight Seeds.— While seeds
are quite constant in chemical composition, there is,
however, a slightly greater amount of total plant food in
heavy- than in light-weight seeds. In the case of wheat,
experiments have shown that the additonal reser\'e food
in heavy-weight seeds favorably influences the growth of
the crop, particularly when the soil is slightly deficient
in available plant food. The additional reserve food in
heavy-weight seeds enables the young plant to reach a
higher stage of growth before being compelled to collect
and assimilate food from the soil. When the soil is in a
high state of fertility the difference in results between
light- and heavy-weight seeds is less noticeable.

Experiment 6j. — Calculation of plant food in seeds. Weigh
100 phimp, well-formed wheat kernels. Then from this weight
and the following data compute the grams of nitrogen, phosphoric
acid and potash per 1,000 wheat kernels. Wheat contains about
2 per cent, nitrogen, and 90 per cent, dry matter. The dry matter
contains about 2 per cent, ash, approximately 50 per cent, of the
ash being P.2O5, and 33 per cent. KjO. Repeat the experiment,
using 100 shrunken wheat kernels. Tabulate and compare the
results.

Questions. — (i) How much more reserve plant food is there as
N, P2O5 and KjO in heavy- than in light-weight seeds?

Movement of Plant Juices

339. Joint Action of Cliemical and Piiysical Agents.

— The compounds produced in the leaves of plants are
transported and stored in other parts, as the seeds or
roots ; this is brought about by the joint action of

CHEMISTRY OF PLANT GROWTH 24I

physical and chemical agents. This action can best be
understood by first considering a few of the properties
of plant tissues, as porosity, capillarity, and osmosis.

340. Porosity of Tissues is a property common to all
forms'of matter, and one possessed particularly by vege-
table substances. The living plant not only admits the
passage of water through its tissues, but absorbs it until
the pores are filled. Animal and vegetable tissues always
possess the power to take up and tenaciously hold
water within their fibers. This is, in part, due to capil-
lary action (see Section 20, Chemistry of Soils and Fer-
tilizers). Capillarity, assisted by evaporation, explains
onl}^ in part the movement of the plant juices. Com-
pounds formed within the leaf must be transported in an
opposite direction to that taken by the sap in moving
from the roots to the leaves. This movement is effected
by osmosis, and chemical reaction within the cells.

341. Osmosis. — When a bottle filled with a solution of
salt, colored with litmus, is placed in a large vessel of
water, the bottle will discharge its contents into the
water and the movement of the solutions can be followed
with the eye. If sugar and salt solutions are separated
by a membrane, there is a gradual interchange between
the two solutions. Some of the sugar finds its way into
the salt solution, and some of the salt finds its way into
the sugar solution. This action or interchange is still
further increased when the solutions are of different
densities and when chemical action is taking place on
both sides of the membrane. Such an action takes place
in plant tissues, which are composed of a large number

242 AGRICULTURAL CHEMISTRY

of small cells, the walls of which serve in part, as mem-
branes, and offer but little resistance to diffusion. The
cells are filled with sap, which is acid in nature and con-
tains numerous solid substances in solution. Between
the cells are intercellular spaces filled with sap of differ-
ent density from that within the cells and charged
with numerous alkaline matters taken from the soil.
Here, then, are nearly the same conditions as when the
salt and sugar were separated, and the result, osmosis, is
the same in each case. Within the cell walls active chem-
ical changes are taking place which aid in this inter-
change. It cannot be said that there is a constant flow of
sap in any one direction, as blood flows in the animal body.
It was formerly believed that there were two courses of sap
in the plant, upward and downward. The movement of
the plant juices is now considered as due to (i) capillary
action, aided by evaporation which disturbs the equilib-
rium of the plant juices, together with (2) osmosis aided
by chemical action within the cells. These factors are, to
a certain extent, mutually dependent upon each other.
By their joint action, aided by the chemical changes
within the plant, the water from the soil is taken into
the plant through the roots with the mineral matter in
solution, which serves as food, and finds its waj^ all
through the plant, finally returning to the roots charged
with the material that can be made only in the leaf and by
the aid of light and sunshine.

Chlorophyl and Protoplasm
342. Chemical Action in Leaves of Plants. — All of
the organic compounds of plants are produced within the

CHEMISTRY OF PLANT GROWTH 243

cells of the leaves. The mineral food and nitrogen taken
from the soil and the carbon dioxid from the air are
chemically united in the cells of the leaves to form the
various non-nitrogenous and nitrogenous compounds of
plants. Chlorophyl and protoplasm are the two substances
which take the most active part in the production of the
organic matter.

343. Chlorophyl is the name applied to the material
which imparts the green color to plants. It is not a
simple compound, but is composed of a number of closely
related organic compounds. The chlorophyl body con-
tains both organic and mineral matter. Chlorophyllan is
one of the compounds obtained from chlorophyl. Iron,
phosphorus and magnesium are among the more im-
portant mineral elements necessary for the functional
activity of the chlorophyl body. This mineral matter is
combined with the organic compounds which form a part
of the chlorophyl grain. Chlorophyl is contained in the
active livmg cells of plants, but makes up only a small
part of the contents of the cell.

344. Protoplasm.— The chlorophyl body is suspended
in a gelatinous, colorless liquid called protoplasm which is
composed mostly of proteid and albuminoid materials.
It is the living substance of the plant organism, and is
the part which gives life and activity. In chemical com-
position, it is exceedingly complex, and is composed of a
number of proteids, albuminoids and other organic com-
pounds. The protoplasm, aided by the chlorophyl, has
the power of combining the food elements and producing

244 AGRICULTURAL CHEMISTRY

all of the organic compounds of the plant. Protoplasm
is the living part of both plant and animal cells.

345. Production of Chloropbyl. — When the plant cell
is first formed, the protoplasm contains no green grains.
Small, colorless grains first appear, and then the green-
ing of these grains takes place. The chlorophyl body
may make its appearance in the absence of light, but the
last stage of its development can take place only under
the influence of light and at a higher temperature than
is required for the first stage of the process. With a cool
temperature, there is plant growth, but the vegetation
looks yellow because there is not sufficient heat for the
completion of the second part of the process of chlorophyl
development. Chlorophyl is destroyed by intense light
as well as by the absence of light. It is soluble in
ether and alcohol and is one of the constituents of
ether extract. The green color is easily destroyed,
but the chlorophyl body is quite stable and resists the
action of dilute acids and alkalies. Chlorophyl loses its
activity, and undergoes a decided change in composition
as the plant matures. Some of the elements which com-
pose the chlorophyl, as nitrogen and phosphorus, are
used for seed formation. At the time of the greatest
amount of color in plants, there is the greatest cell
activity and the largest amount of plant tissue is being
produced. When a plant ripens, the decline of activity
of the cells can be observed by the change in the color of
the plant. When corn, for example, ripens, the lower
joints of the stalk turn yellow first, indicating that
growth and activity have ceased in those parts. Then

CHEMISTRY OP PLANT GROWTH 245

the upper leaves become yellow, and finally the husk be-
comes yellow and inactive. Chlorophyl is one of the
principal agents which takes an active part in plant growth,
and whenever chlorophyl is destroyed, plant growth is
checked.

Experiment 68. — Extracting chlorophyl from leaves. Place in
a test-tube, 0.5 gram of dry, green leaves. Add 10 cc. alcohol, shake
vigorously and, after the alcohol is colored green, filter off the
solution, and evaporate to dryness at a low temperature on the
water-bath.

Questions. — (i) Describe the appearance of the chlorophyl
residue. (2) What is chlorophyl ? (3) Of what is it composed?
(4) What other solvents could be used in place of alcohol.

346.. Function of Chlorophyl. — The chief function of
chlorophyl, aided by protoplasm, is the production of
starch and other organic compounds in the cells of plant
leaves. Chlorophyl alone cannot perform this function,
but must be associated with, and aided by, protoplasm,
Minute starch grains are sometimes found within the
chlorophyl grains. The actual growth of starch within
the chlorophyl body can be observed with the microscope.
No other compounds have been found so organically con-
nected with the chlorophyl grains as starch. If a plant
is placed in darkness, both the starch and the coloring-
matter in the plant cells disappear. The plant cell is the
chemical laboratory in which the various organic com-
pounds, as starch, sugar and proteids, are elaborated.
From the cells in the leaves, they are transported to other
parts of the plant as the seeds, roots or tubers, where they
are stored up and serve as reserve food.

347. Production of Organic Hatter. — By the joint

246 AGRICULTURAIv CHEMISTRY

action of the protoplasm and chlorophyl within the plant
cells, starch and all other organic compounds are pro-
duced from the carbon dioxid of the air and from the
water, mineral matter, and nitrogen of the soil. All of
the carbohydrates can be produced from starch as was
stated in Section 289, which discusses the general rela-
tionship existing between the various non-nitrogenous
compounds. Fat, as well as other non-nitrogenous com-
pounds, is produced from starch. Proteids are produced
from amides. By a succession of chemical changes, the
amide molecule takes on fatty acid and carbohydrate
radicals, and as a result, complex proteids are produced.
All of these chemical changes take place within the plant
cell ; and, for the production of the various compounds
which constitute the dry matter of plants, the essential
mineral elements, nitrogen in combination, carbon dioxid
and water, are required.

CHAPTER XXVI
Composition of Plants at Different Stages of Growth

348. Composition and Stage of Growth. — Plants do
not have the same chemical composition at different
stages of growth. The chlorophyl and protoplasm are
most active in the early stages and produce the nitrogenous
compounds more rapidly than the non-nitrogenous ones.
The later stages of growth are utilized mainly for the
production of carbohydrates and for the various chemical
and physical changes incident to ripening and the transfer
of the organic compounds from the leaves to the seeds.
Plants have a different food value at their different
stages of growth as well as a different chemical composi-
tion,

349. Assimilation of flineral Food by the Wheat
Plant. — The various elements of plant food utilized by
spring wheat are assimilated quite rapidly in the early
stages of growth. The mineral matter being essential for
the production of the organic compounds is taken from
the soil in advance of their formation. Before the crop
has completed the first half of its growth, over 75 per
cent, of the total mineral matter has been taken from the
soil. Of the mineral elements, phosphoric acid, potash
and lime are assimilated most rapidly.

350. Assimilation of Nitrogen by the Wheat Plant.

— The nitrogen utilized by the spring wheat crop is
taken from the soil in advance of the mineral matter.

248 AGRICULTURAL CHEMISTRY

Nitrogen is assimilated by the plant more rapidly than
any of the elements which form a part of the organic
compounds. When the plant has completed half its
growth, under normal conditions about 85 per cent, of
the total nitrogen required by the crop has been taken
from the soil. This is one reason why nitrogen and the
essential ash elements should be present in the soil in
available and liberal amounts for a wheat crop. When
the largest amount of any element or compound is taken
as 100, the corresponding amounts present during the
different stages of growth of the wheat plant are as
follows :

Wheat, 50 Wheat, 65 Wheat, 80 Wheat,

days, before days, headed days, milk harvest
heading out. out. state. time.

Total dry matter 46 59 95 100

Organic matter 44 57 90 100

Total nitrogen 86 89 96 100

Potassium oxid 45 88 100 94

Calcium oxid 67 91 100 96

Magnesium oxid 57 68 99 100

Phosplioric anhydrid 80 83 98 100

351. Clover; Rapidity of Growth. — In clover, the same
general order of changes occurs at the different stages of
growth as in wheat, but as the two plants are so unlike,
clover being a biennial and a legume, and wheat an
annual and a grain, the rapidity of growth and formation
of organic compounds in the two plants are naturally
dissimilar. The largest amount of the dry matter in
clover is produced between early and full bloom. During
this period about 60 per cent, of the organic compounds
are formed. As in the case of wheat, the nitrogenous

PLANT GROWTH AT DIFFERENT STAGES 249

compounds are formed more rapidly and in advance of
the non-nitrogenous ones. At the time of early bloom,
about 37 per cent, of the total nitrogenous compounds
have been formed, but the crop at this stage of develop-
ment has only 31 per cent, of the total organic com-
pounds produced during growth. When clover is very
young, before the flower head is visible, only about 10
per cent, of the organic compounds have been produced,
but this organic matter is rich in nitrogenous compounds
as it contains about 15 per cent, of the total amount
assimilated by the crop; a large share of this nitrogen,
however, is in the form of amide compounds. The com-
position of the leaves and stems, at the different stages
of growth, show that, at first, the leaves contain about
2.5 times as much nitrogenous matter as the stems,
while at maturity, there is less than twice as much.
At the time of full bloom, the largest amount of nitroge-
nous matter is present, and it is then in the form of pro-
teids to the extent of about 88 per cent. In the last
stages of growth, there is also a notable increase in the
content of crude fiber. The differences in composition
and feeding value between clover, cut and cured in full
bloom, and at maturity are as follows:

Clover at full bloom.

1. The crop contains less fiber 4. The nutrients in the crop are

than when mature. more evenly distributed.

2. The crop contains its maxi- 5. The crop contains its maxi-

mum amount of proteids. mum amount of essential

3. A smaller yield per acre is oils, which impart palata-

secured than at maturity, bility.

but the crop is more con- 6. The nutrients in the clover

centrated in protein. are more digestible.

250 AGRICULTURAL CHEMISTRY

Clover when ripe.

1. The crop contains a larger 4. Some of the nutrients in the

amount of fiber. crop are transferred to the

2. The crop contains a smaller ^^^<^^' ^^^^'^^S less in the

per cent, of protein than

stems,
when in full bloom. 5- At maturity, there are less

of the essential oils than at
3. A larger yield per acre is any other period.

secured, and the crop is 5. At maturity, the crop is less
more concentrated in car- digestible than at full

bohydrates. bloom.

Composition of Clover at Different Stages of Growth.

Flower head Early Full End of

invisible. bloom. bloom. flowering. Ripe.

Per cent. Per cent. Per cent. Per cent. Per cent

Water 86.00 85.59 74.96 71.65 33.47

Dry matter 14.00 i4-4i 25.04 28.35 66.53

Composition of the Dry Matter.

Ash 10.57 10.22 6.85 7.02 6.21

Ether extract.... 5.35 4.70 5.73 4.26 3.92

Crude protein .. . 23.61 17.19 14.81 14.40 14.06

" fiber 13-37 20.08 24.62 25.28 26.60

Nitrogen-free ex-
tract 47.10 47.81 47-99 49-04 49-21

Composition of the Dry Matter of the Leaves and Stems

Flower head invisible. Early bloom. Third period.

Leaves. Steins. Leaves. Stems. Leaves. Stems.

Per cent. Per cent. Per cent. Per cent. Per cent. Per cent.

Ash 10.02 11.02 10.07 11.30 9.19 4.87

Crude protein . 30.68 1344 27.38 11.25 19-37 11-26

" fiber... 10.48 18.46 10.51 26.32 15-36 35-27

When the largest amount of anj^ compound in the crop
is taken as 100, the percentage amounts at the different
periods of growth are as follows :

PLANT GROWTH AT DIFFERENT STAGES 25 1

Flower head Early Full End of

invisible. bloom. bloom. flowering. Ripe.

Percent. Percent. Percent. Percent. Percent.

Dry matter 9 31 97 100 97

Total ash 14 46 98 100 95

Total nitrogen 15 37 100 96 94

Proteid nitrogen 67 70 88 85 83

Fiber 5 24 92 96 loo

Potassium oxid 15 50 100 94 86

Calcium oxid 15 37 97 100 97

Magnesium oxid 8 35 100 92 91

Phosphoric anhydrid. 14 34 98 100 98

(These tables are from Minn. Expt. Sta. Bull. 34.)

352. Flax; Rapidity of Growth. — The flax plant has a
short growing period, about seventy days, and the plant food
is assimilated at a rapid rate. Before the time of bloom,
the nitrogenous material and mineral matters hav^e been
absorbed in quite large amounts. When 40 per cent, of
the nitrogenous matter has been produced, the flax plant
contains 55 and 60 per cent., respectively, of its total
nitrogen and mineral matter. At the time the flax is in
full bloom, 75 per cent, of the organic compounds have
been formed. After seed formation begins, there is no
nitrogen or mineral matter taken from the soil. Flax is
very rich in nitrogen, containing even more than clover.
This is one of the few crops in which the ash in the seed
exceeds that in the straw; the seed contains about 3.75
per cent, ash, while the straw contains less than 3 per
cent. The oil in the seed is produced mainly from starch
in the later stages of growth. Between full bloom and
maturity, less than 25 per cent, organic matter is pro-
duced. The rate of formation of the organic matter and

252 AGRICULTURAL CHEMISTRY

assimilation of the elements from the soil are given
in the following table :

Before In full Seeds well

bloom. bloom. formed. Ripe.

Percent. Percent. Percent. Percent.

Total organic matter 40 75 95 ico

Ash 60 88 100 98

Total nitrogen 55 80 100 98

Calcium oxid 32 64 98 100

Potassium oxid 55 90 100 95

Phosphoric anhydrid 35 70 98 100

Minn. Expt. vSta. Bull. 47.

Maize (Corn)
353. Importance. — Since Indian corn or maize is grown
over such a wide range of territory, and is used alike as
animal and human food, and as animal food may serve as
either grain or forage, a knowledge of the chemical changes
which take place during its growth, and the composition
of the plant at maturity, will enable the student to utilize
this crop more economically in the feeding of farm
animals. Some of the facts relating to the composition
of corn at different stages of growth and the analyses
given in this chapter are taken largely from Bulletin No.
9, Mo. Agr, Expt. Station.

353- Roots. — The function of the roots is to collect
and assimilate and transport to other parts the nitrogen
and mineral food from the soil. In mature corn, but a
small amount of the essential elements of plant food are
present in the roots, only sufficient for the structure of the
root tissues. During growth, there is always some being
transported to the parts above ground. At maturity, the
dry matter in the roots constitutes about 5 per cent, of

PLANT GROWTH AT DIFFERENT STAGES 253

the dry matter of the plant. The roots contain the
largest amount of fiber and the smallest amount of fat of
any part of the plant. Of the ash elements, soda is
present in greater amounts than in parts above the ground.
In the early stages of growth, the roots are very rich in
iron, which decreases as the plant matures, because of its
being given over to other parts. The nitrogen in the
roots never, at any stage of growth, exceeds 1.25 per
cent, of the dry matter. It is transported to the parts
above ground more rapidly than any other element.
During the last fifteen days of growth, there is but little
mineral food, except magnesia, taken up, and there is a
loss of about 12 per cent, of potash from the roots which
indicates that the retrograde movement of potash at
maturity may extend from the roots back to the soil. In
the later stages of growth, there is a great influx of mag-
nesia. Silica and the non-essential ash elements make
up the larger portion of the ash elements in the mature
plant.

355. Stalk. — The stalk, during growth, undergoes a
decided change in composition ; there is a gradual in-
crease in the content of fiber and a decrease in proteids.
The outside of the stalk has a different chemical com-
position from the pith. The largest per cent, of dry
matter is found in the stalks from two to three weeks
before maturity. As the plant matures, the proteid and
circulatory carbohydrates are transferred to the seed.
When mature, both the pith and stalk have a low protein,
fat and digestible carbohydrate content, and hence a low
feeding value. The pith is somewhat richer in nitroge-

254 AGRICULTURAL CHEMISTRY

nous matter than the stalk. The ash of the stalk is
characteristically rich in silica.

356. Leaves. — Since all of the chemical compounds of
the plant are first produced in the leaves, and then trans-
ported to other parts, it follows that the leaves at different
stages of growth have a variable composition. Since the
cells .of the young leaves contain more protoplasm than
mature leaves, the largest amount of nitrogenous matter
is present there in the earl}^ stages of growth. As the
plant matures, this nitrogenous matter is given up for the
formation of other parts, and then there is a decline in the
percentage amount of nitrogen in the leaves. The largest
amount of dry matter in the leaves is found about six
weeks before maturity. The plant as a whole, however,
increases even more rapidly in dry matter after this
time, but no additional organic matter accumulates in the
leaves but is used for seed formation. As the plant
matures, the total ash in the leaves steadily increases, due
to silica, which is deposited there as inert material, while
that in the stems declines. As the plant matures, the
phosphorus content of the leaves declines, the phosphorus,
like the nitrogen, being stored up in the seeds. The
largest amount of potash in the leaves is at the time of
the largest amount of dry matter, about six weeks before
maturity. Next to the seed, the leaves contain the
largest amounts of protein, fat, and digestible carbohy-
drates of any part of the plant. When green, the leaves
have a higher nitrogen content than when yellow. The
feeding value of corn fodder depends to a great extent
upon the condition of the leaves.

PLANT GROWTH AT DIFFERENT STAGES 255

357. Tassel. — The tassel has some of the chemical
characteristics of the seed ; it is concentrated in nitrogen,
has less fiber, and an ash rich in phosphates. The flower
stalks and anthers yield an ash in composition like that of
the stems, while the ash of the pollen is nearly identical
with that of the matured grain. The pollen is par-
ticularly rich in nitrogen. One of the claims made for
detasseling corn, is to prevent loss of nitrogen and phos-
phoric acid through the pollen. It is estimated that the
nitrogen removed in the pollen amounts to from 5 to
10 pounds per acre. The fresh and dried silk (stigmas)
shows a decline in both nitrogen and phosphoric acid
after fertilization.

358. Husk. — The husk when first formed has all of the
materials for the development of the seed, and its compo-
sition at different stages of growth shows a gradual trans,
fer of its constituents to the ripening grain. When fully
mature, the husks are much poorer in ash and nitrogen
than the leaves or stems, but are not so poor as the cob.
The cob remains functionally active longer than any other
part of the plant, and is composed largely of cellulose and
pentose compounds, and contains but little protein or fat.

359. Ripening Period.— The corn plant, at first, absorbs
its mineral food and nitrogen at a very rapid rate. In fact,
there is but little mineral matter or nitrogen assimilated
during the last few weeks of growth. The last stage of
development is a period of rearrangement and transporta-
tion of the compounds from the leaves to the seed. The
composition of the different parts of the corn plant when
mature and of the ash is given in the following table :

256

AGRICULTURAL CHEMISTRY

M

^'

ro

10

ON

10 On

d

^,"

•4

_■

d "

•pua3;H CN

l-H CO

•qoo ^

"?

*-<

CO

1— i t-H

CO d

•-'

10

<N

00

CO

't °^

■^snH ^

^ 0

M3

d

CO
CO

'saaiiiuv If?

vO

CO

CO

■5)- ^O

10

•I3SSB.T d

HI 0

CO •

P4 10

0

0

CO

N

CO 0

CO

cs

0

CO
CO

M CO

CO

»o

N

00

- 0

(-.

10

c

M

CO CO t^ "^
t-l d oi NO

t^ i-i On On ■^
C^ 6 O (S 6

CO <^

d o

2 ° M

M CO r^ O ts
(N On t^ CO On

CO ^.
d 00

•nsnod

•S3AB31 ^

•spisino

■RIH

0

>*

«

CO

q

M

NO

«

Cm (D
0

fi

•""

d

•^
t^

NO

w

I- <J

M

r^

'^t

CO

CO

u

co'

d

00'

NO

S

CO

S

*- ti

NO

in

00

0^

CO

<

ON

^

0 C

M

d

■^

^ 06

to

c

t^

0

CO

10

0

M

Q

2;

oo_

to

M

0

1-1

NO

►-;

0

10

0

<N

m'

ON

CO

^

'a-

^

CI

CO

VO

tfi

0

p

NO

"?

CO

CO

00

«S

lO

0, u

CN

NO

•^

10

rt

0^

t/5
0

Ph

'^ 0

tN

NO

0

'"'

0

tN

g

1> s

ON

10

ON

■^

cs

'T

0

Ph U

m'

d

J,

NO

co'

0

0

■*

'^

•a

p. s «j --

A .A s^ O
< W ^1 o,

t>^ CO CO On On
d r^ <^' no' d

O "0 NO CO lO

CTN d f^ f^ t^

CO CO '-'

M CO
CO ^

O nJn
►m' CO

NO 00 ^ O n CO

w NO fN* co' "o d

rO CO O i-i
OD «' 06 >-<'

►M T ►-; i-i •-; 10 q

r^ CO d w CO d ^

M t^ ■^ NO q c< '=*■

m' t^ '^ 10 •* d ■*

ro CO *^

n

, -^ '-^ i-* m

.^ O O "- tS

C/3 P-( C/2 h-I ^

C3 -t; ^ Ij

CHAPTER XXVII

Factors Which Influence the Composition and

Feeding Value of Crops

The main factors which influence the composition and
feeding vakie of crops are: (i) Seed, (2) soil, (3) cli-
mate, (4) stage of maturity, (5) method of preparation
as food, and (6) combination with other foods.

360. Seed. — The composition and individuality of the
seed influence the composition and feeding value of the
forage crop produced. Heavy-weight seeds are usually
more mature and contain a larger amount of reserve plant
food than those of light weight (see Section 338). Ex-
periments by Heilreigel show that the heavier the seed,
the more vigorous the young plant. Where there was
not an overabundance of plant food in the soil, the differ-
ence in vigor of plants was discernible even up to the time
of harvest. Experiments at the Illinois Station (Bull.
Nos. 53 and 55) show that by careful selection of seed
corn, the percentage amount of nitrogenous matter in the
grain may be increased from 0.5 to 1.25 per cent. Not
all of the cereals respond as does corn to the influence of
seed selection to produce variations in chemical compo-
sition.

The care and storage which the seed receives prior to
planting also influences its vitality. When seed corn is
stored in a damp or poorly ventilated place, the excessive
amount of moisture results in injuring the vigor of the
germ. Seed wheat is often injured by being stored in

258 AGRICULTURAL CHEMISTRY

elevators where bin-burning caused by fermentation takes
place. Sound heavy seeds of full maturity always give
the best crop returns. Forage crops are more susceptible
to seed influences than are grain crops, because the leaves
and stems of plants are less constant in composition than
is the seed.

361. Soil. — The condition of the soil as to available
plant food has a material influence upon composition, and
in promoting a balanced crop growth. Experiments
conducted at the Connecticut Experiment Station (Storr's
Annual Reports, 1 898, 1 899) show that fodder crops grown
with a liberal supply of nitrogen have a tendency to con-
tain more of the nitrogenous compounds than similar
crops grown wdth a scant supply. The nitrogen and
available mineral matter increase the activity of the pro-
toplasm and chlorophyl in the production of all of the
organic compounds. With a larger amount of available
plant food, particularly nitrogen, a larger amount of
foilage is produced. All foliage crops, grown upon rich
soils, have larger leaves and a higher nitrogen content
than those grown on poor soils.

The condition of the soil influences the composition of
leaves and stems to a greater extent than it does the com-
position and character of the seeds because they are more
constant in composition. The selection of seed corn has
a greater influence upon the composition and feeding
value of corn fodder than it has upon the grain. Fodder
crops, produced upon fertile soils and under favorable
climatic conditions have the highest feeding value. The

FEEDING VAIvUE OF CROPS 259

condition of the soil, as to acidity or alkalinity, also in-
fluences the character and composition of crops. Crops
produced upon acid soils hav^e a different appearance from
those grown upon mildly alkaline soils. An unbalanced
condition of plant food in the soil produces an unbalanced
crop growth. It is not possible, however, by the use of
manures or the selection of seeds, to entirely change the
composition of crops. In the extensive experiments by
Lawes and Gilbert (Rothamsted Memoirs, Vol. Ill), the
continued use of nitrogen and mineral manures for a
period of twenty years showed no material increase in the
amount of nitrogenous matter in the wheat. In similar
experiments with potatoes, in which nitrogenous ma-
nures alone were used, there was an increase of 0.05 per
cent, of nitrogenous matter. The sugar-beet has been
extensively changed in composition by cultivation. The
content of sugar has been increased from 8 to 16 per
cent. Wheat and other grains show material differences
in weight and composition when grown upon different
types of soil. Experiments have been made where wheat
grown from one lot of seed under different climatic and
soil conditions showed a difference of 18 bushels per acre
in yield, and 8 pounds per bushel in weight (Minn.
Expt. Sta. Bull. No. 23). Forage crops produced upon
soils of high fertility have a higher feeding value than
crops grown upon poor soils. At the Minnesota Experi-
ment Station, timothy and corn fodder grown on land
that had been manured and rotated, and similar crops
grown on unmanured land showed the following amounts
of protein :

26o AGRICULTURAL CHEMISTRY

Timothy hay grown on Corn fodder grown on

manured unmanured manured unmanured

land. land. land. land.

Per cent. Per cent. Per cent. Per cent.

Crude protein (dry

matter basis) ... 8.75 6.45 8.85 6.32

362. Climate. — In the early stages of plant growth, the
nitrogenous compounds are produced more abundantly
than are the non-nitrogenous (Section 351). If the
growing season is in any way cut short, the crop has a
slightly larger amount of nitrogenous matter than if
normal conditions prevail. Any shortening of the grow-
ing period or forcing of the crop to maturity lessens the
per cent, of dry matter, increases the nitrogenous com-
pounds, and decreases the carbohydrates. The composi-
tion of grains is influenced by climatic conditions, particu-
larly at the time of seed formation when growth is
often checked before all of the compounds have been
transferred from the leaves to the seeds ; shrunken or
immature grain is the result. Such grain contains less
starch and more nitrogenous compounds than that which
has fully matured. Experiments with potatoes by Lawes
and Gilbert show that they too are, to a slight extent,
influenced in composition and starch content by climatic
conditions ; the longer the growing period, the larger the
amount of starch. A short and forcing growing season,
together with a fertile soil, has a tendency to produce
crops of high nitrogen content.

363. Stage of riaturity. — Since all crops at first pro-
duce nitrogenous compounds in larger amounts than" at
later stages, it follows that early cut crops contain pro-
portionally more nitrogen than those cut later. This in-

FEEDING VALUE OF CROPS 261

crease in nitrogenous matter is, however, at the expense
of the total dry matter in the crop. If crops are cut too
early, that is, before early bloom, too much of the nitro-
gen is in the form of amides, some of which are changed
to proteids at a later stage. Early cutting results in
securing a smaller yield per acre of dry matter more con-
centrated in nitrogenous compounds. When fodder crops
are cut at early or full bloom, the nutrients are more
evenly distributed than at maturity when some of the
proteids and carbohydrates have been transferred from
the leaves to the seeds, leaving stems and leaves with a
larger amount of fiber and less protein. The composi-
tion and comparative feeding value of clover cut at
different stages of growth are given in Section 351.

364. Hethod of Preparation as Food. — The method of
curing and preparing a fodder affects its food value.
Overdrying causes a mechanical loss of leaves which
gives the fodder a different composition and feeding
value from that when the leaves are all secured. Bleach-
ing results in partial destruction of the chlorophyl and a
loss of the essential oils that impart palatability. Other
chemical changes which have a tendency to make the
fodder less digestible also take place. A mechanical
loss of leaves and exposure to leaching rains result in a
loss of nutritive value. The materials extracted are the
most soluble and digestible. A heavy, leaching rain may
extract 10 per cent, or more of the nutrients, making the
leached fodder less available and less palatable.

The method of storing and the mechanical condition of
a fodder also influence, to a limited extent, the avail-

262 AGRICULTURAL CHEMISTRY

ability of the nutrients. The influence which the com-
bination of fodders has upon digestibility and food value
is discussed in Chapter XXXV.

365. Improving the Feeding Value of ForageCrops. —

The main factors, as seed, fertility of soil, stage of
maturity, and care which the fodder receives, are all
under the control of the farmer, climate being the only
factor that is not directly controllable. Lack of moisture
in dry seasons can, however, in part, be overcome by
shallow cultivation. By careful selection of seed, con-
serving the fertility of the soil, and suitable methods of
cultivation and storage, it is possible not only to increase
the yield but also to change the chemical composition and
feeding value of forage crops. As yet, experiments have
not demonstrated the extent to which all crops are sus-
ceptible to these influences.

CHAPTER XXVIII
Composition of Coarse Fodders

366. The Term Coarse Fodders is applied to animal
foods which usually contain large amounts of crude fiber,
and, while bulky in nature, are essential foods, many of
them having a high nutritive value. A coarse fodder
may be either green or field-cured ; pasture grass, timothy
hay, and corn fodder are all examples of coarse fodders.
The proteid content of coarse fodders ranges from 4 per
cent, and less, in straw, to 12 per cent, and more, in
clover and legumes.

367. Straw. — The straw from wheat, oats, barley, and
rye contains from 36 to 38 per cent, of crude fiber, and
less than 4 per cent, of crude protein, oat straw being the
richest. The amount of fat in straw is small, rarely exceed-
ing 1.5 per cent. Straw contains from 6 to 9 per cent.
of water. The pentose compounds make up a large por-
tion of the nitrogen- ^

free extract. Straw
is a food poor in pro-
tein, fat and digestible
carbohydrates, and
contains a high per
cent, of ligno-cellu-
lose, pentose, and ash
materials. Straw may

NITROGEN FREE EXT

WHEAT STRAW

Fig. 84. — Composition of a bale of
wheat straw.

produce some heat in a ration, but for the production of
muscle or the repair of proteid matter, it occupies about

264

AGRICULTURAL CHEMISTRY

the lowest place in the list of animal foods. The various
factors which influence the composition of plants (see
Chapter XXVII) affect the composition of the straw.
That from grain immaturely ripened has higher feeding
value than from grain fully ripened, because in the unripe
state less of the nutrients have been removed for seed
formation. The greener the straw, the higher its food
value.

368. Timothy Hay. — Timothy hay has more protein,
but in many respects the same general characteristics as
straw. The per cent, of fiber usually ranges from 28 to
32 per cent, or more, which is from 6 to 10 per cent, less

than in straw. The

amount of crude pro-
tein ranges from 5.5 to
9 per cent, according
to the conditions under
which the crop was
grown. Average tim-
othy hay contains 7.5
per cent, which is
about twice as much
as found in straw . The amount of ether extract is about
2.25 per cent. , of which a large portion is non-fatty mate-
rial. As in the case of straw, the nitrogen-free extract of
timothy consists largely of pentose bodies ; there is also a
small amount of soluble carbohydrates. While timothy
hay is not rich in protein, it is a valuable fodder, particu-
larly when one of fair energy-producing power is desired,
as for feeding work horses.

TIMOTHY HAT
Fig. 85.-

-Cotnposition of a bale of
timothy hay.

COMPOSITION OF COARSE FODDERS 265

369. Hay, Similar to Timotliy. — Millet, blue grass
hay, and the numerous varieties of native prairie hay, have
about the same general composition and feeding value as
timothy hay. Each, however, differs from timothy to a
slight extent both in chemical composition and structure
of parts, some being preferable to others for feeding
certain kinds of animals. These hays, particularly native
prairie hays, vary in protein content from 6 to 11 per cent,
according to the conditions under which they are grown
and other factors which affect their composition. Tim-
othy, blue grass and the numerous varieties of prairie
hay, are classed as coarse fodders containing a low to
a medium amount of crude protein.

370. Oat Hay.— When oats are cut at the heading-out
stage and cured as hay, they make a valuable fodder
which compares favorably with the best grades of timothy
hay, and usually contains slightly more protein than
timothy or hays of similar character. Oat hay should be
cured for fodder while the nutrients are evenly dis-
tributed, and before they are transported and stored up
in the grain.

371. Hay, Similar to Oat Hay — Wheat and other
cereals, cut at the right stage, have a similar composi-
tion and feeding value to oat hay. In localities where
the climatic conditions do not admit of the growth of
perennial grasses, these forage crops are grown in their
stead.

372. Bromus Inermis varies in composition and feed-
ing value according to the stage when cut. When over-

266

AGRICULTURAL CHEMISTRY

ripe, its protein content is between that of straw and
timothy hay. If cut or pastured while young, it has a
high feeding value. In this crop, the non-nitrogenous
compounds, particularly fiber, are formed at a rapid rate
in the last stages of growth.

373. Clover Hay is characteristically rich in crude pro-
tein, containing nearly twice as much as poor grades of
timoth5^ It also contains less crude fiber and more ether
extract. The large amount of crude protein and other
nutrients makes it one of the most valuable fodders that
can be produced for growing, fattening, or milk-giving ani-
mals. There is no coarse fodder except alfalfa that has so
high a protein content as clover when grown and cured un-
der the best conditions.
Clover ash is of differ-
ent composition from
that of timothy. It
contains a small
amount of silica and a
CLOVER HAY large amount of lime,

Fig. 86.— Composition of a bale of clover haj'. while timothy asll

contains a large amount of silica and a relatively small
amount of lime. The nitrogen-free extract of clover is
largely pentose materials. The composition and com-
parative feeding value of early- and late-cut clover are
given in Section 351. In curing clover hay, it should be
the aim to prevent mechanical losses of leaves during the
handling of the crop. When clover hay is fed to stock,
less grain and milled products are required than when
hays of lower crude protein content are used. There are a

COMPOSITION OF COARSE FODDERS 267

number of varieties of clover ; alsike, crimson, scarlet
and white clovers, all having about the same general
composition. Each, however, has characteristic habits of
growth which makes it peculiarly adapted to certain soil
and climatic conditions.

374. Alfalfa and Fodders Similar to Clover. — Alfalfa
has somewhat the same general composition and feeding
value as clover, but its physical composition, as density
of tissue and proportion of leaves to stems is different.
It can be grown under different and more adverse climatic
conditions. All members of the leguminous or pulse
family, to which clover, alfalfa, peas, cow peas and vetch
belong, are characteristically rich in protein, and are
among the most valuable forage crops that can be pro-
duced. The discovery, by Heilreigel, of the unique
value of clover and other legumes in assimilating the free
nitrogen of the air by means of the action of micro-organ-
isms associated with the roots of these plants, and of the
use of leguminous crops in increasing the supply of nitro-
gen in the soil, is one of the greatest achievements of
agricultural chemistry. In Plate III, the arrow indicates
one of the nodules which contain the nitrogen-assimi-
lating organisms.

375. Rape. — The rape plant contains nearly as much
crude protein as clover hay. Because of the presence of
certain volatile oils, it cannot be fed to milk-cows with-
out imparting an unpleasant taste to the milk. Rape,
however, is valuable for the feeding of all growing and
fattening animals.

268 AGRICULTURAL CHEMISTRY

376. Pasture Grass.— In the study of the composition
of plants at different stages of growth, it was stated that
the nitrogenous compounds are produced more rapidly
than the non-nitrogenous (Section 351). The dry matter
of pasture grass is more nitrogenous in character than
that of the matured crop. The dry matter of all kinds
of pasture grass is rich in crude protein ; the various
nutrients, however, range between wide limits, accord-
ing to the species of grass, and the conditions affecting
its growth. When a piece of land is grazed, a smaller
amount of total nutrients is secured than if a forage
crop were harvested and fed. In pasturing, the results
are similar to a series of early cuttings, before bloom,
rather than one later cutting as in harvesting a crop.

377. Corn Fodder and Stover. — By corn fodder is
meant the entire corn plant with or without ears, accord-
ing to the conditions under which it has been grown,
while corn stover is the plant after the grain has been re-
moved. Corn fodder is one of the most valuable, pala-
table, and largest yielding crops that can be procured.
When sown so that no ears, or very small ones, are de-
veloped, the leaves and stalks contain all of the nutrients
which would otherwise be stored up in the seed. When
grown under favorable conditions, corn fodder contains
about the same per cent, of crude protein and is equal in
value to the best quality of timothy hay. When field-
cured, it contains from 15 to 30 per cent, of water, from
12 to 25 per cent, of crude fiber, and from 2.5 to 4 per
cent, of ash. In the study of the composition of the corn
plant (Chapter XXVI), the content of crude protein and

COMPOSITION OF COARSK FODDERS

269

other nutrients in the various parts of the plant was con-
sidered. In the production of corn fodder, it should be the
aim to produce a large number of me-
diumly small plants with large leaves,
small or no ears and small stalks. By
so doing, the largest amounts of nutri-
ents most evenly distributed, palata-
ble, and digestible are secured. Corn
stover has more of the characteristics
of a straw crop, and is not as valuable
as corn fodder. When ears are pro-
duced, the protein is stored up in the
grain, and hence less is found in
stalks and leaves. The physical con-
dition and chemical form of the cellu-
lose, as hydrated or lignose, also in-
fluence the feeding value of corn
stover. Corn fodder can be fed to

CORN FODDER

Fig. 87.— Composition of
a shock of corn fodder.

fodder and corn
all kinds of farm
animals, and is one of the cheapest forage crops that can
be grown. It is valuable alike for horses, sheep, and
dairy and beef cattle.

378. Silage, — When silage is prepared, the green ma-
terial is placed in a nearly air-tight compartment. Corn,
clover, or any green crop may be cured as silage. Corn,
however, is the crop most generally given this treatment
and unless otherwise designated, silage usually has refer-
ence to corn fodder prepared in this way.

The chemical changes that take place in the silo are
caused mainly by ferments. Carbon dioxid, hydrocar-
bons, and ammonia in small amounts are among the vola-

270 AGRICULTURAL CHEMISTRY

tile products formed. There is always a loss of dry
matter in curing silage. This is greatest in the top layer
and least in the bottom. The losses in the different
sections of a large silo may range from 5 to 25 per
cent. In a large silo the losses are less than in a small
one, and they need not exceed 5 per cent, of the dry
matter.

The average of a number of trials shows that when
corn fodder is prepared as silage, there is a loss of from
5 to 25 per cent, of dry matter, of which a proportional
amount is protein. Including mechanical losses, there is
nearly the same loss in the field curing of corn fodder as
in its preparation as silage.

The temperature of the silage, when undergoing fer-
mentation, ranges from 35° to 75° C. The lower tem-
peratures generally produce poor silage, while the higher
produce a better quality. In order to produce sweet
silage, the conditions should be such that the temperature
during fermentation is kept above 43° C, so as to render
the acid spore that produces the sour silage less active and
to allow other ferments to act. No appreciable amount of
alcoholic fermentation takes place in the silo. In the
production of silage, the corn should be cut in a green
condition rather than when overripe, and evenly packed
in the silo so that all parts will ferment alike. Compara-
tively short fermentation at a high temperature is prefer-
able to slow fermentation at a low temperature.

COMPOSITION OF COARSE FODDERS

271

Average Composition of American Fodders.
(Jenkins and Winton.)

Field-Cured Fodders.

Corn fodder, average

" " minimum

" " maximum

" leaves, average

" " minimum

*' " maximum

" stalks, average

" " minimum

'* " maximum

" stover, average

" " minimum

" " maximum

Redtop

Timothy:

All analyses

Cut in full bloom

Cut soon after bloom

Cut when nearly ripe

Red clover

Alsike clover

White clover

Alfalfa

Cow pea

Wheat straw

Oat straw

Green Fodders.

Corn fodder (Flint) average . ••
" " " minimum •

*' " " maximum.

Pet.
42.2

22.^
60.2
30.0
14.8
44.0
68.4

51-3
78.5
40.1

15-4

57-4
8.9

13.2

15.0

14.2

14.1

15-3

9-7

9-7

8.4

10.7

9.6

9.2

<
Pet.

2.
I

5

Pet.

4-5
2.7
6.8
6.0
4-5
8.3
1-9
1.2

30
3-8
1.8

8.3
7-9

5-9
6.0

5-7
5.0
12.3
12.8
15-7
14-3
16.6

3-4
4.0

Pet.
14-3
7-5
24.7
21.4
17.4
27.4

II.O

6.9
16.8
19.7
14.1
32.2
28.6

29.0
29.6
28.1

3I-I
24.8
25.6
24.1
25.0
20.1
38.1
37-0

r; 1)
.1: v

Pet.

34-7
20.6
47.8
35-7
27-3
44.1
17.0
II. 2
26.0
31-9
23-3
53-3
47-4

45-0
41.9
44.6

43-7
38.1
40.7

39-3
42.7
42.2

43-4
42.4

W D

Pet.
1.6
0.6
2.5
1.4
0.8

2.2
0.5
0.3
I.O
I.I
0.7
2.2
1-9

25
30

3-0

2.2

3-3

2.9
2.9

2.2
2.9

1-3

2.3

79-8 I.I
51.5 0.7
90.8 1.8

2.0 4.3 12. 1 0.7
0.6 2.1 4.3 0.3
4.0 II. 4 36.3 1.3

272 AGRICULTURAL CHEMISTRY

Green Fodders {continued^. Pct.

Corn fodder (Dent) average . .. 79.0

" " " minimum . 59.5

" " " maximum. 93.6

" " ( Sweet varieties ). .. 79.1

" " (All varieties) 79.3

Redtop in bloom 64.8

Timothy 61.6

Kentucky blue grass 65. i

Legumes :

Red clover 70.8

Alfalfa 71.8

Cowpea 83.6

Soja bean 74.8

Silage :

Corn 79.1 1.4 1.7 6.0 II. I 0.8

<

V .

-a 1-

Pct.

Pct.

Pct.

Pct.

Pct.

1.2

17

5-6

12.0

0.5

0.6

0.5

2.0

3.0

o.i

2-5

3.8

II. 0

27.0

1.6

1-3

1-9

12.8

0.5

1.2

1.8

50

12.2

0-5

2.3

3-3

9-4

19. 1

1.2

2.1

3-1

II. 8

20.2

1.2

2.8

4.1

9-1

17.6

1-3

2.1

4.4

8.1

135

I.I

2.7

4.8

7-4

12.3

I.O

1-7

2.4

4.8

7.1

0.4

2.4

3-0

7-3

11-5

1.0

CHAPTER XXIX
Wheat
379. Structure of Kernel. — The wheat kernel has three
distinct coverings (see Fig. 88): (i) The outer cuticle or
pericarp which is a hard tough coat, composed largely of
ligno cellulose; this is the seed pod in which the seed is
enclosed, and constitutes the main part of the bran. (2)
An inner double cuticle of cellular tissue which is called
the episperm and consists of two hard coats called respec-
tively the inner and outer integument ; this double skin
or layer may be considered one coat and forms a part of

Fig. 88. — Structure of wheat kernel : i, Floury portion; 2, aleurone

layer; 3, the bran composed of three laj'ers; 4, germ

(adapted from Bull. 32, Neb. Station).

the bran. (3) A third, hard, thin skin or layer called the
perisperm. The three bran coats constitute about 5 per
cent, of the weight of the grain. Within these three
bran laj^ers is a single layer of large cells called the
aleurone layer. This is sometimes erroneously called the

274 AGRICULTURAL CHEMISTRY

gluten layer. The germ or embryo plant is present in
the lower part of the kernel and opposite the rounded
end. The germ constitutes about 6 per cent, of the
weight of the kernel. The main part of the seed is the
endosperm which is the floury portion, sometimes incor-
rectly spoken of as the starch cells, in reality composed of
starch, gluten, mineral matter, and other compounds in
small amounts. Additional information in regard to the
structure of the wheat kernel is given in Bulletin No. 32
of the Nebraska Experiment Station.

380. Proteids of Wheat. — Wheat contains the largest
amount of proteids of any of the cereals, and also proteids
of an entirely different character. There are five sepa-
rate proteids in wheat : (i) An albumin (leucosin), (2)
a globulin (edestin), (3) a proteose, and two insoluble
proteids called (4) gliadin, and (5) glutenin, which to-
gether constitute the gluten. Wheat gluten can be ob-
tained by washing a sample of dough from wheat meal or
flour with water to remove the starch and other non -glu-
ten compounds. The gluten mass from hard wheat is
usually elastic and tenacious, varying in quality according
to the nature of the wheat from which it was obtained.
The milling qualities of wheat, and the baking qualities
of flour are determined largely by the composition of the
gluten.

Wheat gluten is composed of two proteids, gliadin and
glutenin ; these form about 85 per cent, of the proteids
of wheat. The gliadin may be extracted from either
gluten or flour with a 70 per cent, solution of alcohol,
and is obtained, after evaporating the alcohol, in the form

WHEAT 275

of thin, transparent flakes which resemble gelatin. In
fact, gliadin was called by the earlier investigators, plant
gelatin. When moistened, the gliadin expands and forms
a mucilagenous mass. When more water is added, a
small amount is dissolved. Gliadin is soluble in dilute
acid and alkali solutions ; in many wheats, particularly
those which have undergone slight fermentation, there is
sufficient acid developed to combine with and render solu-
ble appreciable amounts. Gliadin, like all of the wheat
proteids, is characterized by a high per cent, of nitrogen.
Gliadin takes a very important part in bread-making, and
is the material which binds together the flour to form
dough and enables the mass to expand, retaining the gas
generated by the yeast. Wheat gluten contains from 60
to 70 per cent, of gliadin and from 30 to 40 per cent, of
glutenin.

Glutenin is the proteid which remains after extracting
the gliadin from the gluten. When dry and pure, it
forms a light gray mass which may be reduced to a fine
powder. Glutenin is insoluble in dilute alcohol and salt
solutions and is only sparingly soluble in water, but is
readily soluble in dilute acid and alkali solutions. This
proteid also takes an important part in bread- making. It
combines mechanically with the gliadin and, "serving as
a nucleus to which the gliadin adheres," prevents the
dough from becoming too soft and sticky. When these
two proteids are present in the proportion of about 65 per
cent, of gliadin to 35 per cent, of glutenin, a much better
quality of bread can be produced than from flour contain-
ing the same amount of total proteids but of which 75 per

276 AGRICULTURAL CHEMISTRY

cent, is gliadin and 25 per cent, glutenin. Two samples
of wheat may contain the same amount of gluten, and
the flour from one produce good bread, while that from
the other is of very poor qualit3^ The most valuable
wheats for bread-making purposes are those in which 80
to 85 per cent, of the protein is gluten, and the gluten is
composed of from 60 to 65 per cent, gliadin and 35 to 40
per cent, glutenin. A wheat may produce a good quality
of bread and at the same time contain a low per cent, of
protein, while, on the other hand, poor bread-making
qualities can be associated with a high per cent, of pro-
tein. Glutens w^hich are usually considered the most
valuable for bread-making purposes are hard, elastic, and
of a light yellowish tinge. Poor gluten is dark in color,
has an uneven surface, possesses but little power to re-
coil, and is very sticky.

Experiment 6g. — Gluten from wheat flour. To about 30 grams
of flour made from hard spring wheat, add sufficient water to form
a stiff dough and allow it to stand for half an hour, in order that
the physical properties of the gluten may develop. Place the dough
in a cloth and work it gently with the fingers, while a stream of
water is allowed to flow over it. Continue the washing until
the water that runs away is clear, which indicates that all starch
y as been washed out of the dough. The washing may be completed
with the mass in the hand. Leave this gluten in water until
the gluten from flour made from soft winter wheat has been pre-
pared. Compare the two samples of gluten.

Questions. (i) What is wheat gluten? (2) Describe hard
wheat gluten. (3) How does it differ from soft wheat glut'^n ?
(4) How do the two moist glutens compare as to weight? (5)
Which gluten contains the larger amount of gliadin ? (6) Which
is the better quality of gluten fur bread-making purposes?

•WHKAl*

277

Experiment 70. — Gliadin from flour. Place in a flask 10 grams
of flour, 30 cc. of alcohol, and 20 cc. of water. Cork the flask and
shake, and after a few minutes shake again. Allow the alcohol to
act on the flour for an hour or until the next day. Then filter off
the alcohol solution and evaporate the filtrate to dryness over the
water-bath. Examine the residue. To a portion add a little water.
Burn a little. Treat a little in a test-tube with water containing a
few drops of HCl.

Questions, (i) Describe the appearance of the gliadin. (2)
What was the result when water was added? (3) When burned,
what was the odor of the gliadin, and what does this indicate ? (4)
What effect did the dilute HCl have upon the gliadin? (5) What
is gliadin ?

Composition of Wheat Gluten

1. Scotch fife 14-76

2. Wellman's fife 12.60

3. Red winter wheat 10.73

4. Early Genesee winter 7.98

5. Ladoga 9.54

6. Blue stem 14.20

7. Crimean 11.08

8. Frosted spring wheat . • • • 12.88

9. Calcutta (India) 8.13

10. No. I Chili 7.01

11. La Plata (Argentine Rep. ) 13.38

12. Nicolaeff Azima (Russia). 10.28

13. Oregon white winter 9.23

14. No. 2 red winter wheat. . . 7.01

15. No. 2 hard winter wheat. 8.83

Cm

12.46

10.18

8.68

6.31

8.25

11-75

9-49

6-39

6.70

5.62

11.84

8-74

7-65

556

7-31

Per cent, of

gluten in

form of

O
7.26
6.14
5.60
3-71
5-64
7.84
5-77
4-25
4.90
2.92

4-99
5 70
5-42
3-77
3-99

o
5.20
4.04
3.08

2.60
2.61

3-91

3-72
2. 14
1.80
2.70
6.85

3-04
2-23

1-79
3-32

Glia-
din.

58.3
60.3

64-5
58.8
68.5
66.7
60.8
66.5

73-1
52.0

42.1
65.2

70.8
67.8
54-6

Glute-

uiii.

381. Relation of Nitrogen in Wheat to Nitrogen Con-
tent of Flour. — Medium-sized, well-formed wheat kernels

278 AGRICULTURAL CHEMISTRY

usually contain more nitrogen and gluten than large,
rotund kernels. The size of the germ, the proportion of
aleurone to endosperm, and the nitrogen content of the
endosperm or floury portion are the three factors which
determine the relation of the nitrogen in the wheat to the
nitrogen in the flour. Ordinarily, the germ makes up
about 7 per cent, of the weight of the kernel, and the
endosperm from 82 to 86 per cent. When the amount of
endosperm is increased, there is proportionally less germ,
and aleurone, and a larger amount of flour is secured.
The size of the wheat kernel together with the size of the
indentation marking the germ area indicate approxi-
mately the amount of germ in the kernel. The larger
the amount of germ and aleurone, the smaller the amount
of flour recovered when the wheat is milled. As a general
rule, wheats which contain the largest amount of nitro-
gen produce the most nitrogenous flours, but the total
nitrogen in the wheat cannot always be taken as an index
of that in the flour. Two wheats frequently contain
about the same total nitrogen but the nitrogen is distrib-
uted differently in each ; in one a larger portion is present in
the germ and aleurone, and in the other a larger amount
is in the endosperm and hence recovered as flour. In the
following table, the per cent, of protein in the grain and
that in the patent flour recovered by the modern roller
process of milling are given. These tests were made
under the supervision of the author in two of the large
flour mills of Minneapolis, Minn. The percentage
amounts of wheat recovered as patent flour were about
the same in all of the tests.

WHEAT

2/9

Per Cent, of Protein.

Mill B
Wheat. Flour.

1519

14.60

15

44

14.13

15

75

Mill C

14.00

i5
15
14

50
33

13.90
14.65
13.88

15

51

14.44

15
15

00
15

13-94
14.06

15

33

12.50

15

00

12.56

15

19

14.19

382. Influence of Fertilizers upon Composition of
Wheat. — Experiments by Lawes and Gilbert (Rotham-
sted Memoirs, Vol. Ill) show that the different kinds of
manure, as nitrogenous, mixed and mineral, influence
the yield but not materially the composition of the grain.
During the time of the experiment, covering a period of
twenty years, the nitrogen, phosphoric acid, and potash
in the dry matter of the grain were fairly constant, and
when different manures were used, there w^ere no greater
variations in the composition of the grain than were
observed between crops upon the same plots similarly
manured during different seasons. Climatic conditions
influenced the composition of the kernel to a greater
extent than did fertilizers.

383. Variations in Composition of Wheat. — In Jen-
kins'and Winton's "Average Composition of American
Feeding Stuffs," spring wheat is given as containing 12.5

28o AGRICUIvTURAL CHEMISTRY

per cent, protein and winter wheat 1 1.8 per cent. In
both spring and winter wheat, variations in protein from
8 to 16 percent, are noticeable. While average wheat
contains 12.5 per cent., some samples contain as low as 8
and others as high as 18 per cent.

The greatest differences in composition are noticeable
when wheat grown at different seasons is compared.
Five samples of the 1891 crop of wheat analyzed by the
Minnesota Experiment Station contained 12.01 percent,
of protein. The wheat was of unusually high milling
and baking value. In 1892, six samples from the same
localities showed 13.22 per cent, of protein, and in 1901,
14 samples contained 15.21 per cent.

Some of the effects of climate and soil upon the phys-
ical and chemical properties of wheat are noted in Bulletin
No. 18, Part 9, Division of Chemistry, U. S. Department
of Agriculture, from which the following paragraphs are
taken :

' ' The inherent tendency to change which is found in
all grains is most prominent in wheat ; it may be fostered
by selection and by modifying such of the conditions of
environment as it is in the power of man to effect. The
most powerful element to contend with is the character
of the season or unfavorable climatic conditions. The
injury done in this way is well illustrated in Colorado,
and it would seem advisable in such cases to seek seed
from a source where everything has been favorable, and
begin selection again. It must be borne in mind that
selection must be kept up continuously, and that rever-
sion takes place more easily than improvement. It took

WHEAT 281

but one season to seriously injure Professor Blount's
wheats, but it will be two or more years before they have
recovered from that injury. Hallett, in England, was
able to make his celebrated pedigree wheat by selection,
carried on through many years, but the same wheat
grown by the ordinary farmer under unfavorable con-
ditions for a few years without care has reverted to an
ordinary sort of grain.

' ' The effect of climate is well illustrated by four speci-
mens of wheat which are to be seen in the collection of
the Chemical Division. Two of these were from Oregon
and Dakota some years ago, and present the most ex-
treme contrast which can be found in this variable grain.
One is light yellow, plump and starchy, and shows on
analysis a very small per cent, of albuminoids ; the other
is one of the small, hard, and dark- colored spring wheats
of Dakota, which are rich in albuminoids. Between these
stand two specimens from Colorado, which have been
raised from seed similar to the Oregon and Dakota wheat.
They are scarcely distinguishable except by a slight dif-
ference in color. The Colorado climate is such as to have
modified these two seed wheats, until after a few years
growth they are hardly distinguishable in the kernel.
All localities having widely different climates, soils, or
other conditions produce their peculiar varieties and
modify those brought to them. The result of these ten-
dencies to change and reversion from lack of care in seed
selection or other cause has led to the practice of change
of seed among farmers. A source is sought where either
through greater care or more favorable conditions the

282 AGRICULTURAI, CHEMISTRY

desired variety has been able to hold its own. Some-
times this change is rendered necessary by conditions
which are beyond the power of man to modify. As an
example, No. lo of Professor Blount's wheats, known as
" Oregon Club," a white variety from Oregon, has been
deteriorating every 3'ear since it has been grown in Colo-
rado, w^hereas if the seed had been supplied every season
directly from Oregon, the quality would probably have
remained the same. In extension of this illustration the
fact may be mentioned that the annual renewal of the
seed from a desirable and favorable source often makes it
possible to raise cereals where otherwise climatic con-
ditions would render their cultivation impossible through
rapid reversion. This is particular!}" the case with
extremes in latitude, the effect of which is not founded
so much upon the composition of the crop as on the yield
and size of the grain."

384. Storage of Wheat in Elevators. — When new
wheat is stored in elevators, a fermentation change takes
place known as "sweating." This affects, to a slight
extent, the chemical composition and milling qualities of
the grain. When wheat is not fully matured oris damp,
the fermentation which takes place causes the tempera-
ture to rise to 140° or more and occasionally high enough
to cause spontaneous combustion. Thoroughly sound
wheat undergoes but little change in temperature even
when stored in large elevators where 120,000 bushels are
placed in one compartment. The changes which take
place during storage are brought about b)^ the enzymes
or soluble ferments in the grain, and the organized fer-

WHEAT 283

ments and moulds that are present on the surface of the
grain. When wheat has been thoroughly cleaned, it
does not readily undergo fermentation, while uncleaned,
damp and unsound wheats deteriorate.

385. Grading of Wheat. — Wheat is graded entirely
upon the basis of its physical properties, as : Weight per
bushel, size and appearance of the kernels, freedom from
foreign seeds, soundness of the kernel and absence of
blemishes caused by frost, bleaching, sun scalding or
sprouting. The spring and winter wheat grades estab-
lished for the 1902 crop by the Minnesota Railroad and
Warehouse Commission, are as follows :

No. I hard spring wheat must be sound, bright and well cleaned,
and must be composed mostly of hard Scotch fife, and weigh not less
than 58 pounds to the measured bushel.

No. I northern spring wheat must be sound and well cleaned, and
must be composed equally of the hard and soft varieties of spring
wheat, and weigh not less than 57 pounds to the measured bushel.

No. 2 northern spring wheat must be sound and reasonably clean,
this grade to include all wheat not suitable for the higher grades
on account of smut, barley, or too much king heads, cockle and
oats, or any other defects, and to weigh not less than 56 pounds to
the measured bushel.

No. 3 spring wheat shall comprise all inferior shrunken spring
wheat weighing not less than 54 pounds to the measured bushel.

Note. Hard, flinty wheat, of good color, containing no appreci-
able admixture of soft wheat, may be admitted into the grade of
No. 2 northern spring and No. 3 spring wheat, provided the test
weight of the same is not more than one pound less than the mini-
mum test weight required by the existing rules for said grades, and
provided further that such wheat is in all other respects qualified
for admission into such grades.

284 AGRICULTURAL CHEMISTRY

Rejected spring wheat shall include all spring wheat grown badly
bleached, or for any other cause unfit for No. 3 wheat.

Note. Wheat containing admixture of "rice" or "goose" wheat
will in no case grade better than rejected.

" No grade" wheat. All spring wheat that is in a heating condi-
tion, too musty or too damp to be safe for warehousing, or that is
badly bin-burnt, badly damaged, exceedinglj' dirt)-, or otherwise
unfit for storage shall be classed as "no grade' ' with inspector's nota-
tion as to quality and condition.

Note. The amount of dirt in all wheat shall be determined by
the inspectors.

No. I white winter shall be sound, well cleaned, reasonably
plump, and composed of the white varieties.

No. I winter to be sound, well cleaned, reasonably plump, and
composed of the mixed white and red winter.

No. 2 winter to be sound, reasonably clean, and composed of the
mixed white and red winter.

No. 3 winter shall comprise all winter wheat fit for warehousing,
weighing not less than 54 pounds to the measured bushel, not sound
enough or otherwise unfit for No. 2 of the other grades.

Rejected winter, fit for warehousing but otherwise unfit for No. 3.

386. Composition of Unsound Wheat. — When wheat
fails to fully mature or is affected by frost, fungus dis-
ease, as rust or smut, or excessive heat causing bleach-
ing, the composition of the kernel is affected. Such
wheats usually contain a larger percentage of soluble car-
bohydrates, organic acids, and soluble proteids than fully
matured wheat. Generally, the percentage amount of
protein is higher although sometimes it is lower than in
normal wheat. Wheat which has been damaged by
bleaching, frost or fungus disease gives a lower yield of
flour with poorer keeping mnd bread-making qualities.

WHEAT 285

Sound wheat of high- milling qualities usually contains
not more than 0.25 per cent, of acid bodies, less than 2
per cent, of soluble carbohydrates, and i per cent, sol-
uble proteids.

387. Composition of Different Varieties of Wheat. —
The different varieties of wheat, as spelt and durum, are
similar in composition to ordinary wheat with minor vari-
ations in protein and fiber content. Spelt has a chaffy
covering which gives it somewhat the same proximate
composition as barley, but when the chaff is removed
the seed has about the same general composition as
wheat. In durum, the percentage of protein varies with
the conditions under which the grain is grown. In the
table given at the close of this chapter, it will be seen
that durum has about the same content of proteid matter
and other nutrients as hard spring wheat grown under
similar conditions.

Experiment 71. — Grading wheat. Make the following tests with
three samples of wheat, (i) Obtain the weight per quart (dry
measure), and then calculate the weight per bushel of each. (2)
Weigh 100 kernels of each sample. (3) Place ten representative
kernels (of each) end to end and measure the length in millimeters
and inches. (4) Note the color and appearance of each sample.
(5) Observe if the kernels are " well filled ;" (6) free from weed
seeds and if there are any indications of smut, frosting, or bleach-
ing. (7) Assign a grade to each sample (see Section 3S5).

388. American and Foreign Wheats. — A compilation
of analyses of wheats and other cereals grown in different
countries has been made by Konig. Absolute compari-
sons as to composition cannot be made because of numer-
ous local factors which affect the wheat, as climate and

286 AGRICULTURAL CHEMISTRY

soil. As great a difference is found in the composition
of wheats raised in various parts of the United States, as
between wheats of different countries where there exist
"imilar varieties of climate and soil. In the case of
American wheats, the tables given were compiled before
any large number of Northwestern wheats were analj-zed,
hence the protein content is low because so small a number
of wheats of highest protein content are included in the
averages. In general, the tables of analyses show that
wheat grown in tropical climates is less nitrogenous than
that grown in more northern latitudes on equally fertile
soils. In making use of the figures given in the follow-
ing tables, it should be remembered that the comparisons
are only relative as some of the samples contain a much
larger amount of moisture than others, and an equal num-
ber, or samples proportional to the wheat-growing regions,
are not included in the averages.

389. Wheat as Animal Food. — Wheat is not generally
used for fattening farm animals because of its high value
as human food. Occasionally, however, it is more
economical to use it in preference to other grains for the
feeding of stock. Experiments have shown that it has a
high feeding value. As a food for growing pigs, it is
somewhat preferable to corn ; for fattening pigs, there is
but little difference between wheat and corn. The best
results, however, are obtained when wheat is ground and
fed with other grains. A mixture of equal parts of
ground wheat and corn gives better results than when
either wheat or corn is fed alone. When the price of
wheat is low and it can be purchased for the same

WHEAT 287

or less per pound than corn, it will pay to use wheat for
feeding farm animals. As a food for dairy animals,
ground wheat is fully equal to either corn or a mixture
of corn and barley, and when fed to fattening steers,
ground wheat produces about the same results as ground
corn.

390. Wheat as Human Food. — Wheat is used as human
food more extensively than any other cereal. This is
due largely to its being produced over wider ranges of
latitude and its containing proteids specially adapted to
bread-making. With the exception of rye, wheat is the
only grain which contains gliadin, the proteid which
forms the dough and with the gas causes expan-
sion of the mass during the process of bread-making.

Composition of Wheat

(Mainly from Jenkins & Winton, Bull. II, U. S. Dept. Agr., Office
of Expt. Sta. )

I 22 5 1^ g^ ^

p- Oft w ^i a« <i

Pet. Pet. Pet. Pet. Pet. Pet.

Wheat, spring 10.4 12.5 2.2 71.2 1.8 1.9

Wheat, spring (max.) 13.4 15.4 2.6 78.7 2.3 2.6

Wheat, spring (min.) 8.1 8.1 1.8 66.1 1.3 1.5

Wheat, winter 10.5 11. 8 2.1 72.0 1.8 1.8

+ Wheat, spelt' lo.o 11. 3 2.3 63.9 9.2 3.3

+ Wheat, durum"'' 10.7 15.0 2.4 ( 69.9 ) 2.0

+ Wheat, No. 163' 11. 2 15.8 2.3 ( 68.8 ) 1.9

1 Minn, analyses.

2 Average of thirteen northern grown samples.

3 Spring wheat grown under similar conditions as durum.

288

AGRICULTURAI. CHEMISTRY

■c 5 Cm Ji 00 d CO lA r^ m5 lo <i\ oi CO i-^ I do' I ctn r-^
f J >^

-■u-mOn ^4^^lOO^lOvO^^LO\OTtOvO^D•0^\0

v. i^gt^ 0^lOOO M t^vOvO lOvO tr)CO t-^-* • t^CO

<1 '^ o i-i" 1-,' cj m' fi (-«■ M ►-■ _■ W M M M M 'mm

'rti^i.-S'^D ovDm -Cn-O •00^•<N-^•0^^

pUliSio mCNCO •ro•c^•0— •coc^•r^^..

Otc <-' c~i ci 01 <N ■ <^ * pi ■ C) cJ ' i-> i-i 1-^ w

hOi,-i-!0 iOfO>-'vOONOOvOrO'-iT)-MroOOt^lO

ttt^'^^" wN'-iw'-iwi-lMMMMl-.cil-'clcJ

i,.-u,^'i-i rorOa\to>OlOONCOT)-\DlOcOO'OOM

O^JJgU-j ONCSCNCT^M3vOaN'OVDrO'^i-iO'-;^Cr>

fLi 'S '^ o m" d '-' pj "^ f^' i~~- d d t^' a^ r^ >-<' I-' o I-.' cN

.SiU5"5rO o t^ — CO l^vO -D-rOOl O^ ^ CO io<~90nc<1

gsPH^jrO ri-'^rOr0^tNrO>->ioro<~^J>-<t''^OCf\

^ 00

S.s a

8 -n

§ -3 g

(J s

.^"s i

bo

a « a'i: "!n

o a

Pi

<^ 'C " 'C 5 ;^ N vo

>. en

S

o o

(^ u

03 tfi en tn

^ 'T^.'o. fl "o. "o. "o. 7^ "rl rt rt cj n

S3 SBSHS^

o cs ?. rt C .2

•2 <J
tn u

CHAPTER XXX
Maize (Indian corn)

391. Structure of the Kernel.— Corn has somewhat
the same general structure as wheat. The seed coat, how-
ever, is composed of two instead of three layers (see Fig-.
89). Within the seed coat or hull (i) there is a hard
aleurone layer (2) which
is thicker at the sides
than at the crown. The
floury portion (4) which
is usually hard and flinty,
makes uj) the larger
part of the kernel while
the germ (3) constitutes
about 10 per cent, of the
weight. The propor-
tional amounts of germ,
floury portion, and aleu-
rone layer, differ with
individual samples. The
hulls make up about 5.5
to 6 per cent, of the
kernel, while about 85
per cent, is present in
the floury portion and aleurone layer. In the milling of
corn, as in the milling of wheat, a mechanical separation
of the different parts is effected.

392. Composition of Corn.— Corn is fairly constant in

Fig. 89.— Structure of corn kernel: i,
Seed coat; 2, aleurone layer; 3, germ;
4, floury portion (adapted from n! J. Expt.
Station Bull. J.

290 AGRICULTURAL CHEMISTRY

composition. As the result of a large number of analyses
made by the Department of Agriculture, the following
conclusion is drawn : "A study of all the analyses which
have been made reveals the fact that maize is one of the
most unvariable of the cereals, maintaining under the
most different climatic conditions, a most remarkable uni-
formity of composition, varying chiefly in the size, color,
and general physical characteristics of its kernels rather
than in their composition."

From the figures given at the close of the next chapter
it will be observed that corn contains a much larger
amount of fat than wheat, also a somewhat smaller
amount of protein ; the nitrogen-free extract, which is
mainly starch, is about the same in amount in both. In-
vestigations at the Illinois Experiment Station show that
all of the kernels upon the same ear are fairly constant
in composition, although the kernels on the tip of the ear
have a tendency to contain slightly less protein than those
either in the middle or at the base; the differences in both
protein and carbohydrates in a few extreme cases was about
I per cent. The composition of the kernel is slightly in-
fluenced also by the stage of maturity. If, for any rea-
son, corn fails to reach full maturity, there is usually a
somewhat larger amount of protein and smaller amount
of carbohydrates in the dry matter.

393. Proteids of Corn. — The proteids of corn are quite
different in character from those of wheat. Small
amounts of albumin and globulin are present but the
larger portion of the corn proteids is in insoluble forms
called zeius, one of which is soluble and the other insol-

MAIZE

291

uble iu alcohol. The zeius differ in both physical and
chemical composition from wheat gliadin. The corn
proteids contain about i part nitrogen to every 6.23
parts proteid material, while in wheat there is about i
part nitrogen to 5.7 of proteids.

394. Nitrogenous and Non- Nitrogenous Corn The

germ and aleurone layers ar? more nitrogenous in char-
acter than the interior or floury portion of the kernel.
Since the proportion of germ and aleurone in corn, as in
wheat, ivaries with individual samples, the nitrogenous
matter, being greater in these parts, also varies. Taking
advantage of this knowl-
edge, it is possible, by
mechanical means, to
distinguish corn samples
of high from those of low
proteid content. Hop-
kins, of the Illinois
Experiment Station, was
the first to direct atten-
tion to this fact (Bulle-
tin 55, Illinois Expt.
Station).

"By making cross sec-
tions and longitudinal
sections of several kernels
from an ear of corn, one

can judge, with a very pig. 9o.-Nitrogenous and non-nitroge-
"iflti^fnntnr-vT- rl<:io-rfi<=. r^f cr- nous corn; i, Corn with 14.92 per cent, pro-
SatlSiaClOry aegree Ot aC- tein; 2, com with 7.76 per cent, protein.

curacy, whether the corn is rich or poor in protein. The

292 AGRICULTURAL CHEMISTRY

illustration (Fig. 90) here shown was made from a photo-
graph taken of the corn kernels and sections with a mag-
nification of three diameters. At the left are two sections
and a whole kernel from corn containing 14.92 per cent, of
protein. The sections and kernel at the right are from corn
containing 7.76 per cent, of protein. About one-fourth
of the kernel was cut off from the tip end in making the
cross sections. In the longitudinal sections the tip end
of the kernel points upward to the right. It will be
seen that in the cross sections the white starchy ln3'er
nearly disappears in the high-protein corn, but becomes
very prominent in the low-protein corn. In the longi-
tudinal sections this difference is also apparent, the white
starch in the high-protein corn being confined almost en-
tirel}^ to the crown end of the kernel, while in the low-
protein corn it extends into the tip end in considerable
amount. The germ in the high- protein corn is somewhat
larger. This is also indicated by the depressions in the
whole kernels."

Exceptions are, however, occasionally observed in the
relation of the form to the protein content of corn, but
in making comparisons in the manner indicated, the few
errors which are liable to occur are in assigning too low
rather than too high a protein value to the sample. In
the selection of seed corn a knowledge of the character-
istic of the kernels as nitrogenous or non-nitrogenous will
be found of value.

Experiment j2. — Select, from a sample of corn, kernels of high-
and kernels of low-protein content. Make longitudinal and cross
sections of some of the kernels, and note the proportion of germ,

MAIZE) 293

aleurone, and floury parts in each. Make a drawing of a repre-
sentative kernel of each kind of corn. Observe hovi^ your rating of
the corn compares with the chemical analysis. Determine the
weight per bushel and assign a grade to the sample.

395. Varieties of Corn — The numerous analyses, which
have been made of the different varieties of corn as dent
or flint, do not show any wide variations in composition
when they are grown under similar conditions. The
main differences are in the amount of coloring-matter and
in the physical characteristics rather than in chemical
composition. Yellow corn contains no more nutrients
than white corn ; there is coloring-matter present in one
and not in the other. Sweet corn contains more sucrose
than other varieties but otherwise it has about the same
general composition as the dent and flint varieties.

396. Grading of Corn.— Corn is graded entirely upon
the basis of its physical properties and soundness rather
than on the basis of chemical composition. The rules
governing the grading of corn adopted by the Minnesota
Railroad and Warehouse Commission in 1902 are as
follows :

No. I yellow corn shall be sound, yellow, dry, plump, and well
cleaned.

No. 2 yellow corn shall be three-fourths yellow, dry, reasonably
clean, but not plump enough for No. i.

No. 3 yellow corn shall be three-fourths yellow, reasonably dry,
reasonably clean, but not sufficiently sound for No. 2.

No. I white corn shall be sound, dry, plump, and well cleaned.

No. 2 white corn shall be seven-eighths white, dry and reason-
ably clean, but not plump enough for No. i.

294 AGRICULTURAL CHEMISTRY

No. 3 white corn shall be seven-eighths white, reasonably dry and
reasonably clean, but not sufficiently sound for No. 2.

No. I corn shall be mixed corn of choice quality, sound, dr}^, and
well cleaned.

No. 2 corn shall be mixed corn, drj', reasonably clean, but not
good enough for No. i.

No. 3 corn shall be mixed corn, reasonably dry and reasonably
clean, but not sufficiently sound for No. 2.

No. 4 corn shall include all corn not wet and not in heating con-
dition that is unfit to grade No. 3.

No grade corn : All corn that is in a heating condition, too
musty or too damp to be safe for warehousing, or that is badly
damaged, exceedingly dirty, shall be classed as no grade.

(These rules are subject to change from year to year.)

397. Corn Products. — When the entire kernel is
ground, coarse cornmeal is the produce. When a part
of the corn bran is removed, fine cornmeal is obtained.
When the bran and germ are removed and the interior
portion of the kernel is reduced as in flour-making, the
product is corn flour. By mechanical means, as in the
manufacture of starch, the proteid matter can be re-
moved. Cornstarch is sold either as a commercial prod-
uct, or is used in the preparation of glucose (see Experi-
ment 49). The germ, bran and glutinous matter are by-
products which form the basis of a number of commercial
feeds. The larger portion of the fat or oil of corn is
present in the germ and is recovered as corn oil. A num-
ber of other products are also obtained from corn.

398. Corn as a Food. — Corn is extensively used both
as human and animal food. Its proteids, however, do
not render it as valuable for bread -making purposes as

MAIZS 295

wheat, and on this account, in some countries, it is not as
generally used for human food. It is, however, one of
the cheapest foods that can be procured, and the preju-
dice against its use as human food because of its being
fed to animals is gradually being overcome. Its value
as animal food is too well known to require further dis-
cussion.

CHAPTER XXXI
Oats, Barley, Rye, Buckwheat, Rice, and Miscel-
laneous Seeds

399. Structure of the Oat Kernel.— Oats are composed
of two parts, the kernel and the hull. The hulls have
the same general composition as straw, and make up
about 30 per cent, of the weight. The different parts of
the oat kernal are : (i) Seed pod, (2) aleurone layer, (3)
germ, and (4) floury portion. The weight per bushel of
oats depends largely upon the amount of hulls ; in some
samples these make up 25 per cent., and in others 35 per
cent, of the weight.

400. Composition of Oats. — When the hulls are in-
cluded, oats have a larger amount of fiber and ash than
any other cereal. The per cent, of fat is higher than in
wheat, barley or rye, and as high as in corn. Hulled
oats have about the same general composition as wheat,
with a tendency to a higher protein content. They are
also characterized by a high per cent, of fat. Variations
in the composition of oats are, to a limited extent,
noticeable. The ratio of hull to kernel influences the
composition more than any other factor. There is not a
great difference in the chemical composition of heavy- and
light-weight oats. Experiments at the Maine Experi-
ment Station show that the differences are mainly in the
amount of nutrients in a given volume of the grain, as a
bushel, rather than in percentage composition. This em-

OATS, BARI^EY, RYE, ETC. 297

phasizes the importance of feeding oats by weight rather
than by measure.

401. Oats as Human and Animal Food. — Oats are used
more extensively as an animal food than as human food.
When the hulls are removed and the oats are prepared
as human food, they have a high value because of
the large amount of available protein, fat and other
nutrients which they contain. As an animal food oats
are especially well adapted for the feeding of horses, be-
cause of their mechanical condition and the com-
paratively large amount of available nutrients. Ex-
periments at the Wisconsin Experiment Station show
that when fed to dairy animals under similar conditions,
oats produce 10 per cent, more milk and butter fat than
the same weight of bran.

402. Barley is used largely for brewing and for animal-
feeding purposes rather than as a human food. There is
less fat, fiber, and ash than in oats, but more protein and
carbohydrates. Barley contains less protein than wheat.
For brewing purposes, perfectly sound and fully matured
barley is necessary, while that which has been slightly
damaged in any way, as by rain, frost or hot winds, is not
suitable for this purpose. Such barley, however, can be
used for feeding purposes and is frequently the cheapest
grain that can be fed by western farmers. Barley is
suitable for the feeding of all kinds of farm animals. The
hulless varieties contain less fiber and more protein and
available carbohydrates. A study of the proteids of bar-
ley shows that there is about i part of nitrogen to

298 AGRICULTURAL CHEMISTRY

every 5.7 parts of protein, which is about the same in
amount as is found in wheat proteids.

403. Rye. — Rye contains proteids similar to wheat,
rendering it suitable for bread- making purposes. How-
ever, rye is more extensively used in this country for the
manufacture of alcoholic beverages than for bread. Rye
resembles wheat in chemical composition more than any
other cereal, although when grown under similar condi-
tions it contains somewhat less protein than wheat. In
the feeding of farm animals, rye must be used with more
caution than wheat. If used in a dairy ration in too
large amounts, it is believed to have a tendency to pro-
duce a slightly inferior quality of milk and butter, but
when fed in small amounts no difficulty is experienced.
In a mixed ration, rye has been found equal to barley and
other cereals for meat production.

404. Rice. — Rice is characterized by a low-protein and
fat content, and a high per cent of carbohydrates. It is
not used to any extent for the feeding of stock, although
a number of its by-products are employed for this pur-
pose.

405. Buckwheat. — The entire kernel contains quite
an appreciable amount of fiber, which is removed in the
preparation of buckwheat flour. The amount of protein
is somewhat less than in wheat and other cereals.
Buckwheat is not extensively used for the feeding of ani-
mals, although some of its by-products are valuable for
this purpose.

406. Flax is a type of oil seed, small in size but with a

OATS, BARLEY, RYE, ETC. 299

large amount of nutrients in the form of fat. Average
flax contains about 38 per cent, of fat which is largely
removed in the manufacture of linseed oil. A bushel of
flax will yield about 19 pounds of oil and 40 pounds of
oil cake. Flax is too concentrated and usually too valu-
able a market crop to be used for animal-feeding pur-
poses. Should the price warrant, it can be used, but it
should be combined with other grains, although 8 pounds
a day have been fed in a dairy ration without apparent ill
results. Unripe and immature flaxseed are often used for
feeding purposes. Other oil seeds, as cotton seed and
rape, are valuable for the oil which they contain, and the
oil cake which is used for feeding purposes.

407. nillet Seed has somewhat the same general com-
position as oats. When fed, however, it should be ground
and combined with other grains.

408. Peas and Beans. — Peas and beans, as well as other
leguminous seeds, are characterized by containing large
amounts of protein and variable amounts of fat. Peas
and beans are alike valuable as human and animal food.
When used as animal food, they should form a part
of a grain ration. They are particularly valuable for
pork production as well as for meat and milk, but their
high price usually prevents their extensive use in ani-
mal-feeding. When they can be produced cheaply and
abundantly, they are among the most valuable foods that
can be used. The proteid of leguminous seeds is largely
in the form of legumin, a casein-like body.

409. Grading of Grains. — Oats, barley, rye and flax

300 AGRICULTURAL CHEMISTRY

are all graded commercially on the basis of their physical
properties, as weight per bushel, maturity, amount of
foreign weed seed, and any fungus disease, or injury
caused by rust or excessive heat. The rules adopted
by the Minnesota Railroad and Warehouse Commis-
sion in 1902, for the grading of barley and rye, are as
follows :

OATS

No. I white oats shall be white, sound, clean, and free from other
grain.

No. 2 white oats shall be seven-eighths white, sweet, reasonably
clean and reasonably free from other grain.

No. 3 white oats shall be seven-eighths white, but not sufficiently
sound and clean for No. 2.

No. 4 white oats shall be seven-eighths white, but not sufficiently
sound and clean for No. 3.

No. I oats shall be mixed oats, sound, clean, and reasonably free
from other grain.

No. 2 oats shall be sweet, reasonably clean, and reasonably free
from other grain.

No. 3 oats shall be all oats that are merchantable and warehous-
able, reasonably clean, not fit for higher grades.

No grade oats : All oats that are in a heating condition, too
musty or too damp to be safe for warehousing, or that are badly
damaged, and exceedingly dirty, shall be classed as no grade.

RYE

No. I rye shall be sound, plump, and well cleaned.

No. 2 rye shall be sound, reasonably clean, and reasonably free
from other grain.

No. 3 rye, all rye slightly damaged, slightly musty, or from any
other cause unfit for No. 2 shall be graded as No. 3.

No grade rye : All rye that is in a heating condition, too
musty or too damp to be safe for warehousing, or that is badly
damaged and exceedingly dirty, shall be classed as no grade.

OATS, BARLEY, RYE, ETC. 30I

BARLEY

No. I barley shall be plump, bright, clean, and free from other
grain.

No. 2 barley shall be sound, of healthy color, not plump enough
for No. I, reasonably clean and reasonably free from other grain.

No. 3 barley shall include all slightly shrunken and otherwise
slightly damaged barley, not good enough for No. 2.

No. 4 barley shall include all barley fit for malting purposes, not
good enough for No 3.

No. 5 barley shall include all barley which is badly damaged or
for any cause unfit for malting purposes, except that barley which
has been chemically treated shall not be graded at all.

No grade barley : All barley that is in a heating condition,
too musty or too damp to be safe for warehousing, or that is badly
damaged and exceedingly dirty, shall be classed as no grade
barley.

FLAXSEED

No. I northwestern flaxseed shall be mature, sound, dry, and
sweet. It shall be northern grown. The maximum quantity of
field, stack, storage, or other damaged seed intermixed shall not
exceed 12.5 per cent. The minimum weight shall be 51 pounds to
the measured bushel of commercially pure seed.

No. I flaxseed shall be northern grown; sound, dry, and free from
mustiness, and carrying not more than 25 per cent, of immature or
field, stack, storage, or other damaged flaxseed, and weighing not
less than 50 pounds to the measured bushel of commercially pure
seed.

Rejected flaxseed : That which is bin-burnt, immature, field-
damaged or musty, and yet not to degree to be unfit for storage,
and having a test weight of not less than 47 pounds to the meas-
ured bushel of commercially pure seed shall be rejected.

No grade flaxseed : That which is damp, warm, moldy, very
musty, or otherwise unfit for storage, or having a weight of less
than 47 pounds to the measured bushel of commercially pure seed
shall be no grade.

(These rules are subject to change from year to year.)

302 AGRICULTURAI. CHEMISTRY

Composition of Grains and Seeds.

(From Jenkins and Winton.)

Nitrogen-
Crude Ether free ex-
Water, protein. extract. tract.
Per cent. Per cent. Per cent. Per cent.

Corn, dent 10.6 10.3 5.0 70.4

" (max.). 19.4 12.8 7.5 75.7

" (min.). 6.2 7.5 3.1 65.4

" flint II. 3 10.5 5.0 70.1

" sweet 8.8 11.6 8.1 66.8

Oats ii.o II. 8 5.0 59.7

Barley 10.9 12.4 18 69.8

Rye II. 6 10.6 1.7 72.5

Rice 12.4 7.4 0.4 79.2

Buckwheat 10.9 10.5 5.4 69.6

Peas' lo.i 21.6 i.o 58.2

Flaxseed' 5.1 27.5 38.6 17.9

Millet seed' 12.5 10.6 3.9 61. i

Navy beans 12.4 22.2 1.4 53.1

1 Minnesota analyses.

Crude
fiber.
Per cent.

Ash.

2.2

1-5

4.8

2.6

0.9

1.0

1-7

1.4

2.8

1-9

9-5

3-0

2.7

2.4

1-7

1-9

0.2

0.4

2.1

1-5

5-7

3-4

7-4

3-5

8.1

3-8

7.2

3-7

CHAPTER XXXII
Mill and By-Products

410. Sources. — In the milling of wheat, the preparation
of cereal foods, the malting of grains, the extracting of
oil from seeds and the manufacture of starch and glucose,
various by-products are obtained which are used for the
feeding of animals.

411. Wheat By-Products. — In the milling of wheat,
about 72 per cent, of the grain is returned as straight and
patent grade flours, 2.5 to 3 per. cent, as low-grade and
red-dog, and 25 per cent, as wheat-offal — bran, shorts and
germ. The separation of the wheat kernel into these
various products is a mechanical operation effected by
rolls for the reduction of the grain, and sieves and bolting-
cloths for the separation of the various products. The
standard grades of flour and the percentage amounts of
each recovered in milling are approximately as follows :

Per cent, of

cleaned wheat

recovered.

1. First patent 56.0

2. Second patent 60.8

3. Straight or standard patent 72.1

4. First clear or first bakers 11. 8

5. Second clear or low-grade 0.5

6. Red-dog • 1.9

7. Shorts middlings 11. 6

8. Bran 13.4

(Straight grade flour is composed of first and second patents and
first clear grade. )

304 AGRICULTURAL CHEMISTRY

412. Wheat Bran is composed mainly of the outer
layers of the wheat kernel separated in the process of
milling (see Fig. 88). Along with the outer layers, some
of the floury portion and aleurone cells are removed, and
find their way into the bran and fine bran or shorts. Wheat
bran varies in chemical composition and feeding value
according to the composition and character of the wheat
used and the process of milling employed. Wheat bran
may contain as low as 14 and as high as 18 per cent, of
crude protein ; average bran contains about 16 per cent.
Two samples of bran may contain the same percentage
amount of protein and not have the same feeding value.
For example, one wheat containing 13 per cent, protein
can be exhaustively milled and 5'ield a bran of 16 per
cent, protein while another wheat with 14 per cent,
imperfectly milled may yield a bran with 16 per cent,
protein. While both brans contain the same amount
of crude protein, 16 per cent., the second sample would
contain the larger amount of available non-nitrogenous
nutrients and with the same per cent, of crude protein
would produce better results in feeding than the first
sample. The lower grades of flour are frequently left in
the bran, imparting a high nutritive value. Spring wheat
bran usually contains more protein than winter wheat
bran. This is due largely to the more nitrogenous char-
acter of the spring wheat. Pure bran should be free from
weed seeds and all foreign matter. Bran occupies a high
position among animal food-stuffs. It is bulky in nature
and can be fed in comparatively large amounts without
injury to animals. Director Henry in " Feeds and Feed-

MILL AND BY-PRODUCTS 305

ing" states : " Next to corn, wheat bran is the great cow
feed of this country. Rich in ash and protein, carrying a
fair amount of starchy matter, its Hght chaffy character
renders it the natural complement of heavy cornmeal.
Though its nutritive constituents approximate those of
cottonseed meal, it mixes well with that feed, causing it
to lie more lightly in the stomach.

' ' The large amount of mineral matter in bran is another
factor of much importance in milk production. In milk
there is much mineral matter, placed there for the frame-
work of the calf, and bran supplies this more abundantly
than most feeding-stuffs.

"Middlings, like bran, are extensively fed to dairy
cows. Being themselves heavy in character, they do not
mix well with heavy feeds like cottonseed-meal and corn-
meal. Dairymen will find middlings much relished by
cows and yielding satisfactory returns. Bran and mid-
dlings are conceded by all who have fed them to favorably
affect the flow of milk. Cows may be fed as much as 6
to 8 pounds of bran daily and from 4 to 6 pounds of mid-
dlings. Bran was at first regarded with favor only by
dairymen. Gradually the steer feeder is learning its
value in connection with other grain in the feed box.
Because of its bulky character and its cooling, slightly
laxative properties, bran is a most excellent diluent for
cornmeal, cottonseed-meal and other heavy food sub-
stances. Where it can be obtained at a reasonable price,
the stockman will find much satisfaction in mixing one-
third its weight of bran with cornmeal."

In commenting upon the feeding value of bran, Jordan,

3o6 AGRICULTURAL CHEMISTRY

in the "Feeding of Animals," states: "No commercial
feeding-stuffs are regarded with greater favor, or are more
widely and largely purchased by American feeders than
the by-products from milling wheat. Wheat bran and
middlings are cattle foods of standard excellence, whether
we consider composition, palatableness or their relation
to the quality of dairy products. ' '

413. Wheat Shorts consist of those outer portions of
the wheat kernel which contain less crude fiber, protein,
and ash than the parts which make up the bran. This
product is practically the fine bran subjected to more com-
plete pulverization and mixed with some low-grade flour.
It is more variable in composition than bran, but for
some purposes, as pig-feeding, is more valuable. When
the wheat germ is added to the shorts, the product is
called middlings or shorts middlings. When used in this
connection, the term middlings means an entirely differ-
ent product from the middlings obtained by the stone
process of flour production ; such middlings are now re-
duced and recovered in the patent grades of flour. Shorts
middlings are richer in protein and fat than ordinary
shorts. When the weed seeds, and the screenings and
scourings of the wheat are mixed with the shorts, a prod-
uct known as shorts feed is obtained. This practice,
however, is not generally followed.

414. Wheat Germ is exceedingly rich in both protein
and fat. About 8 per cent, of the wheat kernel is re-
moved as germ in the process of milling, because if added
to the patent flour, it imparts poor keeping qualities and

MILIv AND BY-PRODUCTS 307

its proteid is not suitable for bread making purposes.
Wheat germ contains a number of nitrogenous and phos-
phorized compounds which can be extracted along with
the oil, and which are laxative in character. On this
account, pure wheat germ cannot be fed alone or in large
amounts in a ration, but when combined with other foods,
It is valuable.

415. Wheat Screenings are a mixture of various seeds
with occasionally the broken and shrunken wheat kernels,
and vary in composition and food value with the different
kinds of weed seeds present. When fed, they should be
finely ground so as to prevent the introduction of foul
weeds on the farm. During recent years, mustard seeds
have been removed from wheat screenings and sold as a
separate product, the oil which they contain being ex-
tracted and used commercially.

416. Linseed Meal. — When the oil is extracted from
flaxseed, linseed cake is obtained which, when ground,
forms linseed meal. Pure linseed meal should contain
36 per cent, crude protein. The darker-colored meals are
those which contain moist oil. Linseed meal is a con-
centrated nitrogenous animal food and is valuable for the
feeding of all kinds of farm animals. When used, it
should be combined with other foods. Linseed meal is
occasionally adulterated with flax screenings. Hence, in
its purchase, if adulteration is suspected, preference
should be given to the nut rather than to the fine ground
meal. The cake itself is not adulterated because weed
seeds and impurities must be removed in order to produce

308 AGRICUI.TURAL CHEMISTRY

a good quality of oil. When the oil is removed from the
flaxseed by naphtha and other chemicals, the product is
called ' ' new process linseed meal ' ' which differs from
pressure process meal by having the oil more thoroughly
extracted and by containing a larger amount of crude
protein.

417. Cottonseed Cake and Meal obtained from cotton-
seed after the removal of hulls and the extraction of the
oil, are concentrated nitrogenous foods. The meal is
lemon-yellow in color and is characteristically rich in
crude protein and ether extract. It contains somewhat
more crude protein than linseed meal. Cottonseed meal
is a concentrated nitrogenous food and can be fed, when
properly combined with other foods, to sheep and beef
and dairy animals. It cannot safely be fed in large
amounts nor for a long period to swine. When used in
a dairy ration as the principal food, it influences the char-
acter of the butter-fat, producing butter with a high melt-
ing-point.

418. Oat Feed is a product obtained in the manufacture
of oatmeal. It is variable in composition and consists of
light-weight oats mixed with oat hulls. Oat hulls have
about the same composition and feeding value as oat
straw and are frequently used for the adulteration of ani-
mal foods. In the purchase and use of oat feeds, par-
ticular attention should be given to their composition.
High-grade oat feed is valuable, but when consisting of
any appreciable amount of oat hulls, the food value is
proportionally lessened.

MILL AND BY-PRODUCTS 309

419. Gluten Meal is a by-product obtained in the manu-
facture of glucose. The soaked corn is broken open
and the germ is liberated and floated off with water.
The oil from the germ is extracted and the germ cake
sold as a commercial product or used for mixing with
other foods. The starch and gluten of the corn are sepa-
rated by mechanical means. The starch being heavier
separates and settles, while the gluten is floated off with
water. The gluten product is dried, ground and sold as
gluten meal which usually contains about 35 per cent, of
protein and 3 per cent, of fat. Gluten feed contains the
corn hulls or bran along with the gluten meal. The
hulls reduce the proportion of protein. Gluten feed
usually contains about 25 per cent, of crude protein but
is quite variable in composition.

420. Malt Sprouts. — When barley is subjected to the
malting process, germination takes place, which results
in changing the starch of the grain to maltose. The
plantlets or sprouts are removed, dried and sold as malt
sprouts. They are nitrogenous in character and contain
about 22 per cent, of crude protein, the larger portion of
which is present in soluble form. Malt sprouts are valu-
able for feeding sheep and beef and dairy stock.

421. Miscellaneous By- Products. — There are a large
number of miscellaneous by-products used for the feeding
of animals, as rye bran, buckwheat middlings, palm-nut
meal, hominy chops, etc. Their composition and general
feeding value can be determined from the table of anal-
yses at the close of the chapter.

3IO

AGRICULTURAL CHEMISTRY

422. Inspection of Feeding-Stuffs. — During recent
years, many of the states have passed laws regulating the
inspection and sale of animal feeding-stuffs. The object
of such laws is to prevent adulteration of animal foods by
requiring manufacturers and dealers to guarantee the per-
centage amounts of crude protein and fat. Many of the
European countries have had such laws in force for a
number of years. It is noticeable that in those countries
and states where feeding-stuffs are subjected to in-
spection, the quality is better than where they are not
inspected.

Experiment 7J. — Graphic composition of foods. Make a draw-
ing of some human or animal food material and indicate graphically,
the percentage amount of the different nutrients. If a hundred

(M-

•;-WAT|R^^\

[ ;-r-.;-7' ■■ ','^-:'-

Fig. 91. — Graphic composition of foods.

millimeter rule is used in the construction of the drawing, each
linear millimeter will correspond to i per cent. If a food contains
12 per cent, water, 12 millimeters are measured ofif to represent the
water in the material, and so for each class of nutrients, an area
corresponding to its percentage amount.

MII.L AND BY-PRODUCTS 3II

Composition of Mill and By-Products

Per
cent.

I^inseed meal (old process). 9.20

" " (new process) 10.10

Cottonseed-meal 8. 20

Malt sprouts 10. 20

Corn and cob meal 15.10

Gluten meal 9.60

" feed 7.80

Oat feed 7. 70

" hulls 7.30

Sugar-beet pulp^ 88.53

Rye bran 11.60

Buckwheat middlings 13.20

Palm-nut meal 8.30

Hominy chops 11. 10

Apple pomace 76. 70

Wheat bran, winter 12.30

" " spring 11.50

" shorts 11.80

" screenings 11.60

Meat scrap 1.33

Wheat flour (Minn.) 11.90

Cornmeal 15.10

Cornflour 12.57

Buckwheat flour 14.60

Oatmeal 7.90

1 Dry matter basis.

<

0
p4

'0 u

fa

Per

Per

Per

Per

Per

cent.

cent.

cent.

cent.

cent.

5.70

32.90

8.90

35.40

7.90

5.80

33-20

9-50

38.40

3-00

7.20

42.30

5.60

23.60

13.10

■5.70

23.20

10.70

48.50

1.70

1.50

8.50

6.60

64.80

3-50

0.70

29.40

1.60

52.40

6.30

1. 10

24.00

5.30

51.20

10.60

3.70

16.00

6.10

59-40

7.10

6.70

3-30

29.70

52.10

1. 00

4.85

9-45

22.40

62.62

0.68

3.60

14.70

3-50

63.80

2.80

4.80

28.90

4.10

41.90

7.10

3-70

14.40

21.40

38.90

13-30

2.50

9.80

3.80

64.50

8.30

0.50

1.40

3-90

16.20

1.30

590

16.00

8.10

53-70

4.00

5- 40

16.10

8.00

54-50

4-50

4.60

14.90

7.40

56.80

4-50

2.90

12.50

4.90

65.10

3.00

8.03

57-69

32.95

0.40

12.60

74-30

0.80

1.40

9.20

1.90

68.70

3.80

0.61

7-13

0.87

78.36

1-33

1. 00

6.90

0.30

75.80

1.40

2.00

14.70

0.90

67.40

7.10

CHAPTER XXXIII
Roots, Tubers, and Fruits

423. General Composition. — Roots, tubers, and fruits
contain a large amount of water and a small amount of
dry matter. The dry matter is composed mainly of non-
nitrogenous compounds as starch and sugar. These foods
all contain small amounts of nitrogenous compounds of
which the larger portion is in amide and non-proteid
forms. Organic acids in small amounts and essential
oils are characteristic features.

424. Potatoes contain about 75 per cent, of water.
The dry matter is largely starch. About half of the
nitrogen is present as proteids of which the larger portion

(^Protein. UFat. ■ Indigestible.

Fig. 92. — Composition of potatoes.

is in the form of soluble albumin. The amount of fat is
small, less than a tenth of i per cent. Potatoes contain
but little cellulose. Tartaric and other organic acids,

ROOTS, TUBERS, AND FRUITS

313

pectose substances, and other compounds are present in
small amounts. When potatoes are stored for any length
of time and fermentation takes place, a portion of the
starch is converted into glucose. In storing them, a low-
temperature and good ventilation are necessary to pre-
vent fermentation. Potatoes are a concentrated non-
nitrogenous food.

425. Carrots contain about half as much dry matter as
potatoes. There is approximately the
same amount of water as in milk, viz., 87
per cent. The 12 per cent, of dry matter
is nearly half sugar, 3 per cent, being
fruit sugar and 3 per cent, other
sugars. Carrots contain 1.20 percent, of
total nitrogenous compounds given as
crude protein in tables of analyses, of
which 40 per cent, is protein. There is
more fat in carrots than in potatoes.

426. Parsnips contain more dry mat-
ter than carrots and have nearly the same
amounts of nitrogenous compounds, fat
and fiber, but less sugar and more starch.
They have about the same general food
value as carrots.

I.FIBER, STARCH.

FAT ETC.
2. SUGAR
0. PROTEIN -t-NI-

TROGENOUS MAT

TER.
4. ASH,

427. Mangel wurzels contain more
water and less dry matter than carrots.
The dry matter, however, is richer in
nitrogenous compounds than that of car-
rots, parsnips, potatoes or beets, which makes the mangels

Fig. 93. — Composi-
tion of carrots.

314 AGRICUI.TURAI, CHEMISTRY

a better balanced food. The 10 per cent, of dry matter
in mangels is a little more than half starch and contains
about 1.40 per cent, of crude protein of which half is pro-
tein. Mangels also contain about i per cent, each of ash
and fiber and a small amount of fat.

428. Apples vary in composition with the variety and
ph^-sical characteristics. They contain from 10 to 16 per
cent, solids, of which 75 per cent, is sugar or allied carbo-
hydrates, and about half a per cent, each is fat and protein.
Among the organic acids, malic predominates. The
flavor and special characteristics depend upon the relative
amounts of the different sugars, as sucrose, levulose and
dextrose, and the organic acids and essential oils which
the apples contain. It is these compounds which give
individuality to apples,

429. Oranges contain from 10 to 15 per cent, of solid
matter, the larger portion (80 per cent.) being sugar.
The citric acid content ranges from i to 2.5 per cent, in
different varieties. The amount of protein, fat and fiber
is small. The ash or mineral matter averages about one-
half per cent, and is composed mainly of potash and lime
with smaller amounts of other compounds. The iron and
sulfur content in some kinds of oranges is larger than is
ordinarily found in other fruits. In average oranges,
the physical composition is as follows : Rind, 20 to 30
per cent. ; pulp, 25 to 35 per cent. ; and juice, 35 to 50
per cent.

430. Lemons differ from oranges in containing larger
amounts of citric acid and smaller amounts of sucrose.

ROOTS, TUBERS, AND FRUITS 315

!evulose and dextrose. The average composition of
lemons is as follows :

Physical composition. Chemical composition.

Per cent. Per cent.

Rind 251035 Solids 10 to 12

Pulp 25 to 35 Sugar 2 to 4

Juice 40 to 55 Citric acid 6 to 9

The ash of the lemon is somewhat similar in composition
to the ash of the orange but is present in larger amount.

431. Strawberries are characterized by containing a
high per cent, of water (90 to 92 per cent.). Sugar and
malic acid are the materials present in largest amounts
while protein, fat, ash and fiber form but a small part of
the composition. Coloring materials and essential oils
are also present in small amounts. While strawberries
are valuable as a food adjunct, they do not supply any
appreciable amount of nutrients. It has been estimated
that it would require 13 pounds of strawberries to supply
the carbohydrates needed for a daily ration to say nothing
of the protein which would require 65 pounds additional.
The malic and other acids present are valuable because
of their antiseptic properties which, added to the appear-
ance and palatability, make strawberries a valuable food
adjunct.

432. Grapes vary in composition according to variety.
They contain from 15 to 20 per cent, of solid matter.
The juice contains from 10 to 15 per cent, or more of
sugar in the form of sucrose, levulose and glucose. The
tartaric acid, which is found in grapes in larger amount
than in other fruits, ranges from i to 1.5 per cent.
Grapes do not contain any appreciable amount of protein

3l6 AGRICULTURAL CHEMISTRY

or fat and while they add some nutrients, as sugar, to a
ration, they do not contribute any large amounts. There
is some food value but it is not as high as is occasionally
claimed for them. Their value, as is the case with other
fruits, is in palatability and indirectly aiding in digestion
and adding value to other foods.

433' Olives, when fully matured and fresh, contain about
15 per cent, of oil. When preserved green, there is
considerably less. Olives also contain small amounts ol
other compounds and essential oils. Pure olive oil is a
valuable food, but is frequently adulterated with refined
cottonseed and other vegetable oils. Olive oil is slightly
laxative in character and assists mechanically in the
digestion of foods by preventing compaction of feces in the
intestines.

434. Dried Fruits. — In preparation for the market,
many fruits are preserved by drying. The dried fruit
has a somewhat different composition from the fresh
fruit because of chemical changes which take place dur-
ing the drying process and the slight loss of volatile and
essential oils. Dried fruits, when free from preservative
agents, are valuable, and can be used to advantage if
fresh fruits are not obtainable.

435. niscellaneous Fruits. — Since the list of fruits
that could be discussed is so large, onl}^ a few examples
have been considered. For additional information upon
the subject, or for data upon fruits not given, the student
is referred to the bulletins of the California Experiment
Station.

ROOTS, TUBERS, AND FRUITS 317

436. Food Value. — When judged only on the basis of
the nutrients present, many vegetables and fruits would
be assigned a low place in the list of foods as they con-
tain only comparatively small amounts. Most fruits are
used in the dietary, not so much with the view of sup-
plying nutrients as for other purposes. The organic
acids, essential oils, and soluble mineral compounds, to-
gether with the digestible form in which the nutrients
are present are the factors which give fruits their unique
value. The organic acids and essential oils impart pala-
tability and assist functionally in the digestive process.
Some fruits, as figs and prunes, contain chemical com-
pounds which are laxative in character. In the human
ration, fresh fruits are as essential and occupy the same
position as do roots and vegetables in animal rations.

CHAPTER XXXIV
Fermentation

437. Insoluble Ferments.— Fermentation is a chemical
change produced by a class of bodies called ferments. Insol-
uble or organized ferments are single celled, microscopic
plants which have a definite structure. Many of them
are bacteria while others are low forms of plant life.
Nearly all secrete definite chemical products capable of
producing fermentation. The insoluble or organized fer-
ments are composed mainly of nitrogenous compounds
but also contain non-nitrogenous and mineral matter.
Some, as the tubercular organism, contain cellulose.

438. Soluble Ferments or Enzymes. — Enzymes are
organic compounds, secreted by cells, and have the
property of producing chemical changes. They are also
called soluble ferments, chemical ferments, and diastases.
There are a great manj' different kinds of soluble ferments
some of which, as diastase and maltase, are capable of
acting upon carbohydrates, while others, as pepsin and
pancreatin, act upon proteid bodies. Enzymes produce
chemical change without entering into the composition
of the substance or giving up any of their own material
to the reactiug compounds. A small amount of diastase
will change a large amount of starch to soluble forms
without losing its power of action. The enzymes are all
soluble in water and are precipitated with strong alcohol.
Their action is not generally retarded by antiseptics and
chemicals which are capable of destroying organized fer-

FERMENTATION 319

ments. When seeds are soaked in water, the diastase
and proteose enzymes are extracted and if precipitated
with alcohol and recovered, they appear as a light gray
powder. An organized ferment is a low form of plant,
while a soluble ferment is a chemical compound.

439. Aerobic and Anaerobic Ferments. — Ferments
which require oxygen for their existence are aerobic
while those which are capable of working in the absence
of oxygen are anaerobic. The aerobic ferments produce
carbon dioxid, water, ammonia and hydrogen sulfid as
final products, while the anaerobic ferments usually pro-
duce intermediate products as organic acids.

440. Conditions Necessary for Fermentation. — The

conditions necessary for fermentation are : ( i ) Moisture,
(2) favorable temperature, (3) a ferment body, and (4)
a fermentable substance. Moisture is necessary in order
that the chemical changes may take place. During
fermentation water frequently enters into the chemical
reaction, as in hydration changes, and is also neces-
sary as a medium of exchange for the chemical products
during the reaction. The most favorable temperatures
for fermentation are between 15° and 60° C. Below
zero and above the boiling-point of water, ferments are
inactive. Some ferments require a different temperature
for activity than others. A ferment body is always neces-
sary in order to start the fermentation change, and in the
absence of a ferment either organized or unorganized, no
fermentation can take place. A fermentable substance,
with the right kind of ferment to act upon it, is also req-

320 AGRlCULTURAI. CHEMISTRY

uisite, as a ferment which acts upon one class of bodies is
incapable, unaided, of acting upon others ; for example,
the peptic ferment is incapable of changing starch to
soluble forms. When a substance is freed from all fer-
ments and is protected from outside sources of contami-
nation, it is in a sterile condition. Many forms of fer-
mentation are produced by the spores of organized fer-
ments gaining access to a material along with dust particles
carried in the air. In the preservation of food, a knowl-
edge of the conditions requisite for fermentation is made
use of. The products formed by ferments are numerous,
as there are ferment bodies capable of acting upon all forms
of organic matter. Some of the ferments assist in the
digestion of food and in the preparation of food products,
while others take an important part in every-day life
affairs, and in agriculture as in the liberation of plant
food. The growth of plants, the preparation of foods,
and their digestion, and the manufacture of food products
all depend largely upon fermentation.

441. Soil Ferments. — In the growth of plants, fer-
ments take an important part, both in the preparation of
the plant food and in the chemical changes which take
place within the plant. Disintegration of the mineral
food of the soil is assisted by ferment action. The nitroge-
nous food of the plant is all prepared in the soil by fer-
ments. The subject of soil ferments is briefly considered
in the ' ' Chemistry of Soils and Fertilizers. ' '

442. Ferments in Seeds. — In the seeds of plants, par-
ticularly matured grains, there are a number of ferments
which take an important part in the process of germina-

FKRMENTATION 32 1

tion. These ferments change the insoluble nitrogenous
and non-nitrogenous compounds to soluble forms, which
are utilized by the young plant as food. If a seed were
deprived of all of its soluble ferments, it would fail to
germinate.

Experiment 7^. — Action of malt on starch. Crush in a mortar
twenty malted barley kernels, transfer to a test-tube, and add
15 cc. water. After twenty-four hours, filter off the solution, and
add it to a flask containing 2 grams of flour and 100 cc. water.
Place the flask in the desk for twenty-four hours ; then filter off
the solution and test a portion for starch with iodin, as in Experi-
ment 45. Test another portion for glucose with Fehling's so-
lution, as in Experiment 48.

Questions. ( i ) What is malted barley ? ( 2 ) What did the water
extract from the barley contain? (3) What effect did this extract
have upon the flour? (4) What did the tests with iodin and Feh-
ling's solution show? (5) Would flour treated with water instead
of malt extract give the same result?

443. Ferments in Bread-flaking. — The yeast plant
employed in bread-making secretes a number of soluble
ferments which produce the desired chemical changes.
The diastase ferment changes the starch to soluble forms,
the alcoholic ferment produces alcohol and carbon dioxid
gas, which expand the dough and make the bread light,
and acid ferments produce acids, which combine with the
gluten proteids and modify their character. In short,
bread-making is simply a series of chemical changes in-
duced by soluble ferments.

Experiment j^. — Alcoholic fermentation. Weigh 10 grams
of flour into a flask, add 50 cc. water and a small piece of 3'east
(one-tenth of a cake). Connect the flask by means of a delivery
tube with the Woulff bottle containing enough clear lime water to

322 AGRICULTURAL CHEMISTRY

cover the end of the tube. Place the flask on a warm sand-bath,
below 85° F., for half an hour. Observe the bubbles of gas given
off and the precipitate formed in the lime water. Do not overheat
the sand-bath.

Questions, (i) What is yeast and what does it contain? (2)
What caused the gas to be given oif ? (3) From what was the gas
formed? (4) Write the reaction with Ca(0H)2. (5) What be-
comes of the alcohol ?

444. Ferment Action and Food Digestion. — The di-
gestion of food is carried on largely by the action of solu-
ble ferments. The digestive tract secretes a number of
these, which act upon the insoluble nutrients and change
them to soluble forms. In fact, the digestion of food is
dependent upon the action of the different ferments in the
digestive tract, as ptyalin in the saliva, pepsin in the
stomach, pancreatin in the duodenum, and diastase and
other ferments in the intestines.

445. Ferments and Food Preservation. — Preservation
of food is dependent upon prevention of ferment action.
The low temperature of cold storage is unfavorable to
the development of ferments. Sterilization is likewise
unfavorable. By means of heat, cold storage, chemicals,
and protection from the spores in the air, perishable food
products are preserved. Some ferments, however, are
not destroyed either by high or low temperatures.

446. Ferments in Butter- and Cheese-flaking. — The

process of butter- and cheese-making is carried on with
the aid of ferments. Milk itself contains enzymes or
soluble ferments and, to a limited extent, is itself capable
of acting as a digestive fluid. Tlie ripening of cream is

FERMENTATION 323

the result of the action of the lactic acid ferment which
changes the lactose (milk-sugar) into lactic acid. In
cheese-making, the rennet used for coagulating the milk
contains a number of ferments which take an important
part in the process. The flavor and odor of butter as
well as of cheese are the results of ferment action. In
butter- and cheese-making, it is the object to control the
action of the desirable ferments and to prevent the unde-
sirable ones from developing. Ropy milk, red spots in
cheese, and floating curds in cheese-making, are all
caused by fermentation. Butyric acid, one of the pro-
ducts found in foul milk and butter, is caused by the
butyric acid ferment. Milk is exceedingly susceptible to
the action of ferments.

Experiment j6. — Lactic fermentation. Place 5 grams milk-sugar,
100 cc. water, 5 cc. skim milk, and two or three crystals of sodium
phosphate in a flask. Leave the flask uncorked in the desk for
twenty-four hours. Then add a few drops of phenol phthale in in-
dicator, and determine the amount of lactic acid, i cc. alkali =
0.009 gram acid.

Questions, (i) Why was milk used in this experiment? (2)
What was produced from the milk-sugar? (3) Why was sodium
phosphate used ? (4) How much acid was produced?

447. Disease-Producing Organisms. — Many diseases
are caused by the action of micro-organisms. The dis-
ease-producing organisms or bacteria invade the body
and rapidly multiply, living upon the fluids and tissues
of the body and producing poisonous products. Typhoid
fever, smallpox, diphtheria, tuberculosis, cholera, and
many other diseases are caused by specific bacteria. The
products produced by the action of the organism are

324 AGRICULTURAL CHEMISTRY

poisonous, and death is often caused by these toxic
bodies. Modern methods of sanitation are based upon
the destruction of disease-producing organisms.

448. Beneficial Organisms. — While many diseases are
caused by micro-organisms, not all micro organisms or
bacteria are injurious. In nearly all foods, there are
large numbers of bacteria which are of a harmless nature.
Some are valuable and beneficial to man, particularly
those which assist in plant nutrition and in the prepara-
tion and digestion of foods.

CHAPTER XXXV
Chemistry of Digestion and Nutrition

449. Digestion, a Biochemical Process. — In the diges-
tion of food, the enzymes or soluble ferments take an im-
portant part. Although digestion is not well understood
it is known to be largely a chemical process brought about
by ferment action, and hence is called a biochemical pro-
cess. The cells in the different parts of the digestive
tract secrete chemical products which produce chemical
changes in the food, rendering it soluble so that the vari-
ous nutrients can be absorbed and used by the body. Any
compound which is capable of undergoing digestion and
being utilized for food purposes is called a nutrient. The
value of any food depends upon the kinds and amounts
of nutrients present. During the process of digestion, a
complex series of chemical changes take place, and as a
result of this process and the assimilation of the food by
the body, heat and energy are produced.

450. Digestion Experiments.— The digestibility of a
food is determined by a digestion experiment. The per-
centage amount of a nutrient which is digested is called
the coefficient of digestibility. Not all of the nutrients
in foods are alike digestible. In clover hay, for example,
65 per cent, of the organic matter is digested, while
only 30 per cent, of the crude fiber and 70 per cent, of
the nitrogen- free extract compounds are digested. Each
compound has its own digestion coefficient. In order to
determine the digestibility of a food, an animal is fed, for

326 AGRICULTURAL CHEMISTRY

a number of da3'S, a weighed amount of food which is
anal3-zed. All of the feces or solid excrements produced
during the experimental period are collected, weighed
and analyzed. After undergoing the process of digestion,
the undigested portions of the food along with a small
amount of digested products are excreted as feces, while
the liquid w^astes of the body contain the products of the
digested food. From the weight of the food consumed
and its analj'sis, the amount of each class of nutrients con-
sumed is determined. From the dry matter of the feces,
the undigested nutrients are likewise determined. The
undigested nutrients subtracted from the total nutrients
in the food consumed give the amounts digested which
are calculated on a percentage basis. In the case of clover
hay, an animal may consume 28 pounds per day containing
12 per cent, protein ; this is equivalent to 3.36 pounds of
protein (28 X 0.12 = 3.36). An account is opened with
the animal in which a charge for 3.3 pounds of protein is
entered. From the 28 pounds of food, 40 pounds of feces
or excrements are obtained, as a large amount of water
is added during the process of digestion. The feces
which are composed largely of the indigestible portions
of the food are analyzed and found to contain 20 per cent,
of dry matter; this is equivalent to 8 pounds of indigesti-
ble matter yielded by the 28 pounds of clover (40 X 0.20
= 8). The dry matter is analyzed and found to contain
15 per cent, of protein ; this is equivalent to 1.2 pounds
of protein (8 X 0.15 = 1.2). The animal was charged
with 3.36 pounds of total protein ; 1.2 pounds are found
to be indigestible, leaving a balance of 2.16 pounds of

DIGESTION AND NUTRITION 327

digestible protein, equivalent to 64 per cent, of the total.
(2.16 -^ 3.36 X 100 = 64). 64 is the digestion coeffi-
cient of the crude protein in this clover hay. In like
manner, the digestion coefficients of all of the nutrients
are determined.

Example. — From the following figures, calculate the digestion
coefficients of the organic matter, ether extract, crude fiber and
nitrogen-free extract of the clover hay. The figures for the com-
position of clover hay are on the basis of the food as fed, while
those for the feces are on the basis of the dry matter.

Composition of clover. Composition of feces
Hay as fed. (Dry matter.)

Water 10.00 ....

Ash 6.90 9.50

Ether extract 3.10 2.10

Crude protein 12.00 15.00

Crude fiber 26.00 30.00

Nitrogen-free extract 42.00 43-40

451. Caloric Value of Foods.— During the process of
digestion, heat is produced in proportion to the calories
contained in the food and the nutrients digested. By
the caloric value of a food is meant the amount of heat
measured in calories which the food yields. A calorie is
the amount of heat required to raise i kilogram of water
1° C. or I pound of water about 4° F. The caloric
value of a food is determined by means of the calorimeter
(Fig. 94). The calorimeter consists of a steel bomb
that is placed in a metal cylinder (Q) (Fig. 95). The
bomb is surrounded by water as indicated in the illus-
tration, and the cylinder containing the bomb and water
is placed within a double-walled fiber receptacle ( T
and U). The bomb itself consists of three parts : The

328

AGRICULTURAL CHEMISTRY

cylinder, which is lined with platinum, the cover, and a

collar to hold the
cover in place
and tightly seal
the bomb. These
three parts of
the apparatus
are shown in
Fig. 96.

The principle
involved in de-
termining the
caloric value of
a food is simple.
A weighed
amount of the
substance is
burned in the
calorimeter and
the rise in tem-
perature of the
water that sur-
rounds the bomb
is noted. The
combustion i s
carried on in
oxygen so as to
be complete, and all means possible are employed to
secure accuracy of results. The substance to be burned,
if it is a material like flour, is made into a pellet by

Fig. 94.— Bomb calorimeter used for determining
the caloric or heat-producing value of foods.

Fig, 95. — Bomb calorimeter, showing interior structure and working parts,
Atwater, Conn. (Storrs) Agr. Expt. Station, annual report, 1897.

330 AGRICULTURAI, CHEMISTRY

means of a press. The object of making the material
into a pellet is that it may form a compact mass and
burn evenly and not be scattered about in the calorim-
eter cylinder and be only partially burned. The pellet
is placed in the small platinum crucible O (Fig. 95).
This crucible is supported by platinum wires attached
to the cover of the calorimeter. Above the crucible a
small coil of fine iron wire is stretched from the
platinum wires. The cover is screwed tightly upon the
cylinder of the bomb and oxygen is admitted from
an oxygen tank under pressure through valve G of
the cover until a pressure of twenty atmospheres is
secured, when the valve is securely closed. The bomb
with the substance to be burned, and charged with
oxygen is placed in the metal cylinder Q, which con-
tains a definite amount of water, the temperature of
which is carefully determined by means of a thermom-
eter that reads to 0.005° C. The water is kept at an
even temperature by means of the metal stirrer SS,
operated by a water motor. A connection is made
with a storage battery which ignites the small iron wire
that is suspended above the substance. The burning
wire falls upon and ignites the material in the platinum
crucible O. The heat from the combustion of the mate-
rial raises the temperature of the water in the calorim-
eter cylinder. A number of readings are taken so as
to secure the actual rise in temperature, caused by the
combustion of the substance. Due allowances are
made for the heat contributed by the combustion
of the iron wire, the heat absorbed by the steel bomb

DIGESTION AND NUTRITION

331

and for other factors that are known and under
control.

The approximate amount of energy which a food will
yield can be determined by the use of the following fac-
tors : Ether extract 4225, and fiber, nitrogen-free ex-
tract, and crude protein i860. These are the numbers of
calories which a pound of each of the nutrients yields.

452. Available Energy of Foods. — Since only a por-
tion of the nutrients of foods is digesti-
ble, not all of the total caloric value
is rendered available to the body.
The digestion process is more com-
plete with non-nitrogenous compounds
than with the proteids. The final
products of oxidation in the case of
starch, sugar and digestible carbohy-
drates are carbon dioxid and water.
These compounds undergo complete
combustion. The final products of di-
gestion of the proteids are amides, the
larger portion of which is excreted as
urea in the liquid waste. This com-
pound, urea, CH^N^O, does not un-
dergo complete oxidation in the body.
If burned in the calorimeter, it would
yield an additional amount of heat.
The term available energy of a food
means simply the total energy avail- Fig- 97-

able to the body and measured in calories,
available energy is obtained by deducting from

The

the

332 AGRICULTURAL CHEMISTRY

total digestible energy, the calories contained in the
products, as urea, which are not completely oxidized. In
the determination of the available energy of foods, the
principle is the same as that explained in the section re-
lating to the digestibility of nutrients. The total number
of calories in a food is determined by the calorimeter ;
the number of calories in the feces is likewise deter-
mined and deducted from the total, as well as the caloric
value of the liquid excrements containing urea. This
gives the energy of the food available to the animal.

453- Net Energy of Foods.— In the process of diges-
tion, particularly of coarse fodders containing much
crude fiber, energy varying with the density of the tissue
is required to render the food available to the body. Of
the total available energy, a portion, and in some cases,
a large amount is used up in rendering the food available,
that is, in carrying on the process of digestion. Means
have been devised whereby the approximate amount of
work required on the part of the animal to render the
food available can be determined. When the energy
used in this way is deducted, it leaves the net energy.
In the case of coarse fodders, a considerable portion of
the energy is used up in the digestion of the food leav-
ing, in some cases, only comparatively little net energy
while less force is required to digest the grains, and a
larger amount of energy is available to the bod5^ The
total, available, and net energy which foods produce are
important factors because one of the objects of food is to
supply nutrients for the production of energy.

454. Digestion of Proteids. — The insoluble proteids

DIGESTION AND NUTRITION 333

are acted upon by the pepsin ferment which is present in
the stomach of animals. Peptones are produced by this
action. Proteids which escape the action of the peptic
ferment are later brought into contact with the tryptic
ferment which is present in the pancreas and lower parts
of the digestive tract. This ferment acts in an alkaline
solution while pepsin requires a slightly acid condition.
The proteids which fail to be digested by either the
peptic or tryptic ferments are usually expelled as indi-
gestible proteids. In normal digestion, the fluids of the
stomach are slightly acid while those of the pancreas and
intestines are alkaline. For the formation of acids and
alkalies, sodium chlorid is essential. From this com-
pound, hydrochloric acid, present in the gastric juice, is
formed, also the alkaline products in the biliary and other
fluids. Sodium chlorid is a normal constituent of the
blood and of many of the vital fluids of the body.

After serving the various purposes in the body, as noted
in Section 305, the proteids are expelled as amides in
either the solid or liquid excrements, the larger portion
being in the form of urea. From the time the proteids
are acted upon by the soluble ferments in the digestive
tract until their products are expelled from the body as
amides, a large number of intermediate substances are
formed. Should the proteids fail to undergo normal
digestion, poisonous products called ptomaines are pro-
duced.

455- Digestion of the Carbohydrates. — Digestion of
the carbohydrates begins with the ptyalin ferment of
the saliva. Carbohydrate digestion takes place mainly

334 AGRICULTURAL CHEMISTRY

in the lower part of the digestive tract where diastase
and other ferment bodies are secreted which change the
insoluble carbohydrates to soluble forms. When com-
pletely digested, carbon dioxid and water are the final
products. Between the soluble carbohydrates formed by
the diastase and other ferments and the final products of
oxidation, carbon dioxid and water, a large number of
intermediate products are formed. Glycogen is one of
these bodies and is a carbohydrate present in small
amounts in the blood but stored up largely in the liver.
The process of carbohydrate digestion is one in which the
soluble ferments take an important part, changing the in-
soluble compounds to soluble and assimilable forms.

456. Digestion of Fats. — Bile and the intestinal fluids
are the main factors which assist in the digestion of fats.
After emulsion or separation into fine particles, the fats
are changed to glycerin and fatty acids by the action of
a ferment body. They are then absorbed and undergo
slow oxidation whereby carbohydrate-like bodies are pro-
duced. These products then undergo the same general
changes as the carbohydrates.

457. Oxygen Necessary for Digestion. — In order that
digestion may proceed in a normal way, a liberal supply
of air is necessary to oxidize the nutrients and to prevent
the formation of poisonous waste products in the body.
In the absence of a liberal supply of air, normal digestion
fails to take place. Oxygen is equally as important as
protein, fat, carbohydrates or water.

458. Factors Influencing Digestion. — There are a

DIGESTION AND NUTRITION 335

number of factors which influence the completeness of
the process of digestion. Some of these factors are :
(i) Mechanical condition of the food, (2) combination
of foods, (3) amount of food consumed, (4) palatability
of the food, and (5) individuality of the animal. A di-
gestion coefficient is a variable factor capable of being in-
fluenced by these and other conditions.

459. riechanical Condition. — The mechanical condi-
tion of a food, as lineness of division and density of par-
ticles, materially influences digestion. As a general rule,
the finer the division the more complete is the digestion.
For example, experiments with pigs have shown that
wheat meal is lo per cent, more digestible than whole
wheat. Experiments with other animals, recorded in
Bulletin No. 77, U. S. Department of Agriculture, Office
of Experiment Stations, giving the digestibility of Ameri-
can feeding-stuffs, show equally large differences. The
finer the division of the particles, the larger is the sur-
face exposed to the action of the digestive fluids. The
density of a material also influences its digestibility. Many
foods contain a fair amount of nutrients, but their me-
chanical condition is such that the nutrients are not easily
rendered available because of the presence of a large
amount of cellulose enclosing and protecting the nutri-
ents, and as a result, digestion and assimilation fail to
take place. This is particularly true of many coarse fod-
ders, as timothy hay and clover when allowed to become
overripe and fibrous. Digestion experiments with such
forage, and with that cut in early bloom, show that when
cut in early bloom, it is more digestible than when over-

336 AGRICULTURAL CHEMISTRY

ripe and woody. In the case of human foods also, fine-
ness of division of the particles favorably affects the com-
pleteness of the digestion process. Graham or coarsely
granulated flour, although it contains more nutrients, is
less digestible and furnishes less total available nutrients
than finely granulated flour. The advisability of grind-
ing animal foods depends entirely upon the cost of the
grinding. Where it can be done on the farm at slight
expense, it invariabl}^ pays to grind grains, particularly
wheat, barley, millet and others which have a hard seed
coat. In the feeding of coarse fodders, their mechanical
condition is an important factor. When shredded corn
fodder is fed, less energy is required on the part of the
animal to render the nutrients available. This results in
the return of a larger amount of net energy from the
food.

460. Combination of Foods.— The way in which a
food is combined and fed in a ration influences its digesti-
bility. When foods are fed singly, they are not as com-
pletely digested as when fed in a well-balanced ration.
For example, experiments have shown that corn alone
when fed to pigs, is not as completely digested as when
combined with shorts and other foods. Some foods as-
sist in the digestion of other foods. W^henever milk is
added to the ration for pigs, a larger amount of pork is
secured than when the same amount of nutrients in other
form is added. The milk assists in the digestion of the
grains with which it is combined. Exact experiments to
show the full extent to which one food influences the
digestibility of another have not as yet been made. In

DIGESTION AND NUTRITION 337

the feeding of farm animals, however, the practical results
which'have been obtained show that this is an important
factor.

461. Amount of Food Consumed. — In the case of
human digestion experiments, results have shown that a
large amount of food is not as completely digested as
a smaller amount. With farm animals, the experiments
have not been so decisive. In some cases, large rations
have been digested as completely as smaller ones. This
is undoubtedly due to individual differences of animals.
Excessive amounts of foods, however, have a tendency
to interfere with normal digestion and the results are not
as satisfactory as when medium rations are fed.

462. Palatability. — In order to have the best results,
the food should be relished by the animals. Palatability
exerts a favorable influence upon digestibility and also
upon the returns in animal products. Overripe and
fibrous fodders are generally lacking in palatability be-
cause in the later stages of growth, there is a smaller
amount of the essential oils and other products that im-
part palatability. The mechanical condition and the
palatability of coarse fodders are closely associated, and
the highest degree of digestibility of grains and fodders
generally accompanies the best mechanical condition.

463. Individuality. — When a number of animals are
fed the same ration, individual differences are observed.
Some animals are capable of digesting all foods more
completely than are others, and some are capable of
digesting one food more completely than another food.

338 AGRICULTURAIv CHEMISTRY

This is due to individuality in digestive power and is
particularly noticeable in experiments with sheep w^here
it has been found that all do not digest the different
foods equally well. Digestion coefficients obtained in ex-
periments with one kind of animal, as sheep, are not al-
ways applicable to other animals. Experiments with
swine have shown that fiber is not as completely digested
as with sheep or cows.

464. niscellaneous Factors Influencing Digestibility.
— Experiments in the cooking of foods show that cooked
foods are no more completely digested by farm animals
than uncooked foods. Cooking, however, is sometimes de-
sirable in order to encourage animals to consume a larger
amount of food. The wetting of food, causing fermenta-
tion, has been found to be slightly beneficial. How-
ever, if wetting is practiced, great care should be exer-
cised to prevent excessive fermentation or the action of
undesirable ferments. The drying and curing of fodders
do not appear to exert any unfavorable influence upon
digestibility provided leaching or excessive bleaching is
avoided. Green fodders, however, appear to be slightly
more digestible than cured fodders. In some cases, the
laxative nature of a food prevents complete absorption of
the nutrients before the material is expelled from the
body.

465. Application of Digestion Coefficients. — Too close
application of digestion coefficients cannot be made, but
general comparisons where the experiments have been
performed under similar conditions are allowable and give
valuable results. The methods used for the determi-

DIGESTION AND NUTRITION 339

nation of digestion coeflScients have not been perfected
and a number of sources of minor error are introduced in
digestion experiments. In the case of the feces, the
ether extract contains bile, nitrogen, cleavage products,
and a number of other non-fatty compounds. Hence the
figures for the digestibility of the ether extract are in-
variably too low. Not all of the nitrogen of the feces is
in indigestible forms, hence there is a tendency for the
digestibility of the crude protein to be too low, then too,
it is difficult to assign an absolute nitrogen factor for the
determination of the crude protein. Notwithstanding
these known imperfections in determining the digestibility
of the food, the general results are of great value to the
farmer as they indicate ways by which the largest re-
turns, due to the highest degree of digestibility, can be
secured. Some of the digestion coefficients of the more
common food materials are given in the following table
which is taken from Bulletin No. 77, U. S. Department
of Agriculture, Office of Experiment Stations :
Digestion Coefficients

oa Cn < UP. (jw ^i wS5
Green Fodders.

Timothy 63.5 65.6 32.2 48.1 55.6 65.7 53.1

i^ent corn r 67.8 69.8 35.6 59.7 60.2 73.7 74.1

Oats 59.5 60.9 53.4 71.8 52.8 62.6 69.2

Red clover 66.1 68.1 55.0 67.0 52.6 77.6 64.5

Silage.

Dent corn silage 65.1 67.1 32.2 49.3 66.7 68.6 80.0

Flint " " 73.1 76.1 32.9 62.8 75.1 76.9 81.8

340

AGRICULTURAL CHEMISTRY

u

*— ^-

■u .

t- y

o ™

0 S

o a

in

22

o5

Uc 0..

65.6 67.4 34.3 51.3 70.6 67.4 80.2

Dent corn silage (imma-
ture )

Cured Fodders.

Timothy (average) 56.6

" before bloom ... 60.7

" past bloom 53.4

Dent corn fodder 64.3

Flint " " 68.6

Dent and flint (immature) 63.9

Dent and flint (mature). 68.2

Corn stover 57.2

Red clover 57.4

Grains and Seeds.

Cornmeal 89.4

Gluten feed 86.3

" meal 89.7

Malt sprouts 67. i

Wheat bran 62.3

Oil- Bearing Seeds.

Cottonseed-meal 73. 7

Linseed meal (old process) 78.7

Roots.

Mangels 78.5

Potatoes (raw) 75.7

Some of the most noticeable facts observed in the table
are as follows : The highest degree of digestibility of a
nutrient is usually obtained with foods which contain the
largest amount of that nutrient. For example, clover
hay contains more crude protein than timothy hay, and
in general, the protein of clover is more completely
digested than that of timothy. In the case of potatoes,

57-9

32.8

46.9

52.5

62.3

52.2

61.5

44.2

56.8

58.8

643

58.4

54-5

30-3

45-1

47.1

60.4

51-9

66.1

30.7

50.4

62.2

68.0

73-6

71.7

42.6

60.0

74-9

70.3

71.4

65-7

37-2

51-7

66.0

66.2

72.2

70.7

30.6

56.7

65.8

72.2

73-9

59-1

32.6

359

64.2

57-9

70.4

59-7

29.1

58.0

54-2

64.4

55-2

89.6

67.9

94-7

92.1

87.3

85.6

78.0

89.2

84.4

90.4

88.2

89.8

94-4

67.2

80.2

32.9

68.1

65.7

77-8

28r.6

69.4

68.0

76.1

23-7

88.4

55-5

60.6

93-3

81.2

88.8

57-0

77-6

88.6

84.8

16.4

74-7

42.8

913

77.0

44-7

.,.

90.4

13.0

DIGESTION AND NUTRITION 34I

there is a large amount of nitrogen-free extract compounds
(starch), and in the table it will be observed that they are
more completely digested than the crude protein which is
present in small amounts. Whenever a food contains
nutrients in small amounts they are in dilute forms, and
are not as completely extracted as when present in larger
amounts. The coarse fodders are not as completely di-
gested as the grains and milled products. In the coarse
fodders, the digestion coefficients range from 30 to 65,
while in grains and milled products, the same nutrient
ranges in digestibility from 70 to 95.

466. Digestible Nutrients of Foods. — When the total
amounts of nutrients in a food are multiplied by the
digestion coefficients, the available nutrients are secured.
For example, clover hay contains 12 per cent, crude pro-
tein which is 60 per cent, digestible. The available or
digestible crude protein of the clover hay is 7.2 (12 X
0.6 = 7.2). In like manner, all of the digestible nutri-
ents of foods are ascertained. The total amount of each
nutrient is multiplied by its digestion coefficient, which
gives the total available or digestible nutrients. When
the average composition of American feeding stuffs and
the average digestion coefficients are used, the average
digestible or available nutrients are obtained. Such a
table is given at the end of the chapter. In the use of
this table, it should be remembered that the figures apply
simply to average conditions, and are susceptible to any
of the influences which affect either the composition or
the digestibility of foods, and while the amounts of
nutrients given are fairly constant, they nevertheless

342 AGRICULTURAL CHEMISTRY

vary. It is possible by giving due care to the production
of crops to secure those containing the largest amounts
of nutrients, and then to feed the crops so as to secure
the highest degree of digestibility, and more nutrients
than are given in the tables at the close of the chapter.
For example, timothy hay may contain from 5 to 9 per
cent, protein. That which contains 5 per cent, is less
completely digested than that containing 9 per cent.
From the timothy with the highest degree of digestibil-
ity, there is about 7 per cent, of the protein digestible
and available, while from that with 5 per cent, of crude
protein, there is from 2.5 to 3 per cent, available. The
availability of the other nutrients also is in favor of the
timothy hay with the larger amount of protein. In the
feeding of farm animals, particular attention should be
given to the production of foods which contain the
largest amounts of nutrients and to combining and using
them so as to secure the highest degree of digestibility.
Digestion experiments have pointed out many ways in
which these objects may be accomplished, and the ex-
periments are valuable because they indicate ways in
which the largest returns can be secured from the fodders
and grains raised and fed upon the farm.

Experiment jj. — Digestible nutrients of foods. Take the di-
mensions of one of the measures given out for the experiment and
calculate its capacity in quarts, dry measure (i quart = 67.2 cubic
inches). Weigh the measure, fill it with oats and weigh again.
From the tables, calculate the pounds of digestible fat, protein and
carbohydrates in one quart of each of the foodstuffs. Tabulate
the results as follows :

DIGESTION AND NUTRITION
DiGESTiBr<K Nutrients in Foods.

343

Name of food.

Net weight of meas-
sure.

Digestible pounds per quart.

Grams.

Pounds.

Fat.

Protein.

C'bhydr'ts.

Oats

Bran

Corn

Oil meal

Flour

Shorts

CHAPTER XXXVI
Rational Feeding of Animals

467. Balanced Rations. — A balanced ration is one
which contains a sufficient amount of nutrients from a
variety of foods to meet the requirements of the animal.
Since the different classes of nutrients serve different pur-
poses in the body, it is the object of rational feeding to
combine foods so as to supply the nutrients in the right
proportion for growth and work or production of milk,
meat or wool. Rational feeding is based upon ( i ) the
food requirements of animals, and (2) the amount of di-
gestible nutrients in foods. The food requirements of
animals are determined by experiments.

468. A riaintenance Ration is one which furnishes all
of the nutrients required for maintaining the weight' of
the body and for performing all of its functions without
allowing any nutrients for growth, work or other pur-
poses. A maintenance ration simply sustains the animal
without making allowance for growth or work. When
an animal is fed a maintenance ration, it neither gains nor
loses in weight ; an equilibrium is established between
the income and outgo of the food. The nitrogen in
the proteids of the food consumed is all returned in
the various waste products of the body. The element
nitrogen is taken as the index for determining the main-
tenance requirements of animals. When the nitrogen in
the waste products equals that in the food consumed, and
no work has been performed, a maintenance ration has

RATIONAL FEEDING OF ANIMALS 345

been fed. Growth, work and animal products are all
produced from the excess of nutrients over those required
for maintenance purposes. For example, a pig weighing
200 pounds requires about five pounds of grain per day
for maintenance. If 5.5 pounds per day are fed, an in-
crease in weight is secured only from the half pound in
excess of the maintenance ration.

469. Standard Rations. — For feeding purposes stand-
ard rations have been proposed, giving the amounts of
nutrients required by different classes of animals for dif-
ferent purposes. These tables have been prepared largely
as the result of digestion experiments and feeding trials.
The table in most common use is that prepared by Woulff
and modified from time to time by various investigators.
This table is given at the close of the chapter.

470. Food Requirements of Animals. — In the feeding
of balanced rations, tables of feeding standards should be
used largely as guides. It is not necessary that the
rations should, in all particulars, absolutely conform to
the standards given. On the other hand, it is not advi-
sable to have the amounts of nutrients in the rations vary
in any large degree from the standards. It is difficult to
specify the amounts of nutrients which, under all con-
ditions, will meet the food requirements of all classes of
animals. In previous chapters, it has been shown that
the composition of forage crops is subject to variation as
is also their digestibility. Hence, tables giving the
amounts of digestible nutrients are only approximately
correct, and if assumed for all fodders and conditions, the
calculated amounts of nutrients would, in some cases,

346 AGRICULTURAI, CHEMISTRY

exceed and in others fall short of the standards given.
On this account, it is not possible to adhere too closely to
fixed rules in the rational feeding of farm animals.
When foods containing the largest amounts of nutrients
are produced and so fed as to secure the highest degree
of digestibility, smaller amounts are required than when
foods low in available nutrients are used and injudiciously
fed.

471. Food Supply at Different Stages of Growth. —
The amount and nature of the food consumed should vary
with the period of growth. Rations for young and grow-
ing animals should contain a larger amount of protein
and a smaller amount of non-nitrogenous compounds
than rations for mature animals. This is because more
food is required for building purposes in the early stages
of growth, than in later stages when more is required
for heat and energy. These facts may be observed from
the table of feeding standards. For example, a calf
three mouths old and weighing 150 pounds requires per
day 0.6 pound digestible protein and 2.4 pounds diges-
tible non-nitrogenous compounds, "When the animal is
a year old and weighs 500 pounds, it requires 1.3 pounds
of digestible protein and 6.9 pounds of digestible non-
nitrogenous compounds. The animal has increased in
weight more than three times while the increased demand
for digestible protein is only about twice as great, but
for the non-nitrogenous compounds four and one-half
times as great.

When an excessive amount of starchy and non-nitro-
genous foods is fed to a young and growing animal,

RATIONAL FEEDING OF ANIMALS 347

there is a tendency toward the production of a poor mus-
cular and bony framework and premature fattening. To
produce balanced growth in young animals, careful
attention should be given to the amount and nature of
the nutrients supplied in the food.

473. Food Requirements of Horses. — In feeding work
horses, the object is to provide available nutrients for the
production of energy because it is the energy from the
food which enables the horse to do his work. Experi-
ments have shown that for maintenance purposes, a
1 000-pound horse requires about 17.5 pounds of hay per
day containing a half pound of digestible protein and 7
to 7.5 pounds of digestible non-nitrogenous compounds.
Such a ration does not provide any nutrients for work.
In the table at the close of the chapter are given the
amounts of nutrients required for average w^ork. Any
increase in work should be followed by a corresponding
increase of food. Average work is best accomplished
with a ration containing 22 to 24 pounds of dry matter
per day of which about i . 8 pounds are digestible protein
and II to 1 1 . 5 pounds are digestible nitrogen-free extract.
It is estimated that about one-third of the energy derived
from the food is utilized as useful energy in the perform-
ance of work. The best results are obtained when an
even draft is made upon an animal, as experiments have
shown that less energy is required for average work con-
tinuously than for severe work for a short time fol-
lowed by rest.

473. Selection of Food for Horses. — For light work, 5
to 7 pounds per day of mixed grains are usually sufficient

348 AGRICULTURAL CHEMISTRY

if combined with 12 to 15 pounds of coarse fodder as
timothy hay. For average work, however, more food is
required, and the amount of grain should be about equal
in weight to the coarse fodder. For heaviest work, the
grain should exceed the fodder in weight. Pure clover
hay, on account of its mechanical condition, is not suita-
ble for the feeding of horses. Timothy hay, blue grass
and the different varieties of prairie haj^ are all. suitable,
if cut and cured when mediuml}' ripe. Early cut
fodders are not as satisfactory for the feeding of horses
as for the feeding of other kinds of animals. There
is a tendency to confine the ration of horses too largely
to one grain, oats, which usually makes an expensive
ration. Experiments have shown that a larger variety
of foods is desirable. Corn, barley, ground wheat, bran
and other milled products are all suitable for fonning part
of the ration for work horses. For purposes of variety,
carrots or potatoes in small amounts may be fed. Oil
meal to the extent of about one-fourth pound per day is
also valuable. For average work, the grinding of grains
is not necessary; for hard work, coarse grinding results
in a return of a larger amount of the net energy of the
foods. ,

474. Foods Required for Beef Production. — Accord-
ing to the table of feeding standards from 25 to 30
pounds dry matter containing 2.5 to 3 pounds digestible
protein, and about 15 pounds digestible carbohydrates are
required for a 1000-pound animal. As pointed out by
Jordan, in the "Feeding of Farm Animals," these stand-
ards are too high for economic feeding. As the result of

RATIONAL FEEDING OF ANIMALS 349

feeding trials, 15 pounds digestible organic matter per
day for a 1000-pound animal have been found sufficient.
A ration containing 15 pounds digestible dry matter,
about 1.80 pounds digestible protein, 13 pounds digestible
nitrogen-free extract compounds and 0.7 pound digestible
ether extract was found satisfactory. When too scant an
amount of protein is supplied in a ration, the meat is of
poorer quality than when more is available so as to pro-
duce a normal amount of circulatory proteids in the
system. In beef production, the aim should be to supply
sufficient available protein for maintenance purposes, and
a small amount for the other needs of the body, the fat
being produced from the less expensive nutrients as car-
bohydrates and ether extract. When the fat is produced
from an excess of protein in the food, the cost of produc-
tion is unnecessarily large. The protein supply in beef
production should vary with the stage of fattening. Ex-
periments at the Pennsylvania Station show that o. 42 pound
digestible protein, 6.77 pounds digestible non-nitrogenous
compounds and 0.13 pound digestible ether extract are
required for maintenance purposes. At different stages
of growth, different amounts of food are required to pro-
duce a pound of gain. This fact is particularly notice-
able in experiments at the Kansas Station from which the
following data are taken :

Grain required for
I pound gain.

After 56 days 7.30

After 84 days 8.07

After 122 days 8.40

After 140 days 9.01

After 168 days 9.27

After 182 days 10.00

35° AGRICULTURAI, CHEMISTRY

In the production of beef, palatability of the ration is
an important factor ; this is best secured by combining a
number of grains and coarse fodders.

475. Selection of Foods for Beef Production. — Foods
which are valuable for milk production are likewise valu-
able for beef production ; bran, oil meal, cottonseed meal,
corn, barley, shorts, middlings and screenings are among
the best grain and milled products for beef production.
Pasture grass, clover hay , alfalfa, corn silage, corn fodder
and mixed hays are all valuable coarse fodders. Roots
and tubers, to the extent of 10 Jo 15 pounds per day, may
also be added to a beef ration. The aVnount of grain
should range from 10 to 18 pounds per day with from 12
to 18 pounds of coarse fodder. Occasionally heavy grain
feeding is resorted to in the fattening of steers. When
grains and milled products are cheap, this practice is
often economical as it converts a cheap grain into a more
valuable marketable product. Ordinarily the cost of pro-
duction is greater with a heavy grain ration than with a
light or medium one, and when more than 12 pounds of
grain per day is fed, the additional amount is fed at a loss.
When grains and feeding-stuffs are high in price, heavy
grain feeding is not economical. In the production of
beef, it should be the aim to secure the larger portion of
growth, as well as the larger portion of the increase dur-
ing the fattening, from high-grade coarse fodders, and
supplement them with medium amounts of grain and
milled products. The amount of grain that can be fed
economically is regulated by its cost and the market price
of the beef product.

RATIONAI^ FEEDING OF ANIMALS 35 1

476. Food Requirements of Dairy Cows. — For the

production of milk, a more liberal supply of digestible
protein is required than for beef production. From 0.4
to 0.5 pound of digestible protein and from 7 to 7.5
pounds of digestible carbohydrates are required for main-
tenance. A ration should contain, in addition, 1.4 to 1.8
pounds digestible protein and 4 to 6 pounds digestible
carbohydrates, because milk cannot be produced econom-
ically on too scant an amount of nutrients. According
to the standard feeding tables, a ration for a cow giving
a heavy yield of milk should contain 32 pounds dry mat-
ter, 3.3 pounds digestible protein and 13 pounds carbohy-
drates. For economic production of milk, this is a larger
amount of protein than is necessary. Under average
conditions, a ration containing about 27 pounds dry mat-
ter, 1.8 to 2 pounds digestible protein, and 11 to 13
pounds digestible carbohydrates will prove more econom-
ical than one containing larger amounts of protein. In a
milk ration, proteids must be furnished for the produc-
tion of the albumin and casein in the milk. In 15 pounds
of milk, there is about one-half pound of proteids, as
albumin and casein, and this must be supplied from the
food. For the production of milk, about as much more
protein is necessary to supply the energy to produce the
milk as is required for maintenance and the milk pro-
teids. In an ordinary dairy ration, about one-fourth of
the proteids is recovered in the milk as casein and
albumin, one-fourth is indigestible, while one-half is
present in the liquid waste and represents the protein re-
quired for maintenance and the production of milk. The

352 AGRICULTURAL CHEMISTRY

amount of nutrients in a dairy ration should vary with
the milk yield, as given in the table of feeding standards,
but it is not necessary to adhere too closely to the figures.

In the calculation of a dairy ration, it will be found
that when ordinary foods are combined, the amount of
ether extract or crude fat will exceed the figures given
in the table. Provided the ration contains the requisite
amount of digestible protein, and does not yield more
than 32,000 calories, there is no objection to the crude
fat amounting to 0.6 pound per day. It should not,
however, in an average ration, exceed 0.75 pound.

477. Selection of Foods for Dairy Cows. — The amount
of grain which a dairy cow should receive varies from 7
to 12 pounds per day. Occasionally 15 pounds can be
fed economically, but, as a rule, medium grain rations of
from 7 to 1 2 pounds produce milk and butter more eco-
nomically than either light or heavy rations. As in beef-
feeding, when more than 12 pounds per day of grain are
fed, the additional amount is not used economically and
is generally a loss. The coarse fodder in a dairy ration
may vary from iS to 50 pounds perdaj', according to the
amount of water present in the foods. The ration should
contain from 25 to 30 pounds of dry matter. When
silage is fed, 20 to 40 pounds may be used because of the
large amount of water present. In the feeding of roots,
from 15 to 20 pounds per day will be found economical.
In feeding dairy cows, it is not desirable to restrict the
ration to one grain or milled product. Better results are
secured from a mixture of two or three grains. No
great differences have been observed in the milk-producing

RATIONAL FEEDING OE ANIMALS 353

value of the different grains and milled products. A
pound of one grain in a mixed ration will produce about
as good results as a pound of another grain. For exam-
ple, wheat has been found to have practically the same
feeding value as corn, oats, or barley. Common farm
grains will give. the same yield of milk and butter- fats as
bran or shorts, and, on the whole, have a tendency to
produce slightly better results. Oil meal in medium
amounts in a ration, produces from 20 to 25 per cent,
better results than bran. Oil meal, cottonseed meal, and
gluten meal all have about the same general milk-pro-
ducing value.

Clover hay, corn silage, corn fodder, alfalfa and oat
hay are among the most valuable coarse fodders for milk
production, preference being usually given to clover hay
when cut in early or full bloom. When silage is not
fed, roots should always form a part of a dairy ration.
Roots are valuable largely because of their palatability
and the favorable influence which they exert upon diges-
tion rather than for any large amount of nutrients.

478. Food Requirements of Swine. — The nutrients
required by swine vary with the stage of growth
more than in the case of other animals. In the earlier
stages of growth, particular attention should be given to
furnishing a liberal supply of available protein and min-
eral matter. A ration for a 100- pound animal should
contain about 0.5 pound digestible protein and 2.5 pounds
digestible carbohydrates while that for a 200-pound ani-
mal should contain about 0.6 pound digestible protein
and nearly 4 pounds digestible caj-bohydrates. For grow-

354 AGRICULTURAI. CHEMISTRY

ing pigs, a mixture of shorts and corn or shorts and
barley with skim milk will be found preferable to any
single grain. Skim milk should not be used in greater
amounts than 3 pounds for each pound of grain. Five
pounds of skim milk will produce as much gain in weight
as one pound of grain. For fattening pigs the grain mix-
ture should contain more corn than shorts. Coarse
ground barley is a valuable food and produces a good
quality of pork. Peas may form about one-third of
the grain mixture. For fattening purposes, foods with
a large amount of digestible protein are not as essential
as for growing animals because the excess of protein is
used for the production of fat which can be produced
from less expensive nutrients as carbohydrates. The
food should not be too concentrated in character. Many
of the grains are so highly digestible that there is present
in the digestive tract only a limited amount of insoluble
matter to dilute the waste products. This is particularly
true of peas and corn. Charcoal and a small amount of
corn- and cob-meal are found useful to correct such de-
ficiencies. A small amount of some forage crop as chopped,
steamed or soaked clover should be at the disposal of the
animal. Wheat, barley and rye, if fed, should be coarsely
ground, but in the case of corn, grinding is not so essen-
tial. Bone-meal, dried blood, and meat scrap are valuable
in a ration for pigs, particularly if corn is the principal
grain used. Among the forage crops, rape, clover, alfalfa,
sorghum and corn will be found most valuable for pork
production.

479. Food Requirements of Sheep. — In the case of

RATIONAL FEEDING OF ANIMALS 355

sheep, the standard rations, as given in the tables, can be
adhered to more closely than for any other class of farm
animals. This is because a large number of feeding trials
and experiments have been made with sheep. More nutri-
ents are required for sheep than for beef animals, and they
are capable of making equally good returns from the food
consumed. Experiments by Lawes and Gilbert have
shovi^n that during the process of fattening only a slight
increase in nitrogen takes place ; the gain in weight is
largely an increase in fat. During the growing period,
a more liberal allowance of available protein is required
than for fattening. Farm foods need but little reinforce-
ment with mill and other products for the production of
mutton. Henry, in "Feeds and Feeding, ' ' states that about
500 pounds of corn and 400 pounds of clover will produce
100 pounds of gain in live weight of lambs, and he gives
these figures for calculating the cost of production. The
grinding of grains is not so necessary in sheep- feeding as
in dairy feeding. Among the grains, corn, barley, wheat
and oats have all been found valuable. Oil meal and
other milled products are also suitable, provided their
cost is not too high. Among the coarse fodders, clover
hay, alfalfa, corn fodder and silage are particularly valu-
able. Roots should also form a part of the ration. Vari-
ety and palatability should be considered.

480. Calculation of Balanced Rations. — In calculating
a balanced ration, the food requirements of the animal,
as given in the table of feeding standards, are first noted.
A reasonable variety of coarse fodders, grains and roots
is selected on the basis of cost, as explained in Section

356 AGRICULTURAL CHEMISTRY

483. A trial ration is then calculated, using the approxi-
mate amounts of foods as given in the various sections
relating to the food requirements of animals. The
amounts of digestible nutrients in the foods selected are
then calculated and the total amounts of the different
nutrients determined. If these correspond with the
figures given in the table, a reasonably well-balanced
ration is secured. In case the nutrients are present in
the right proportion but deficient in amounts, the weights
of foods used are increased; if excessive, they are reduced.
Should the ration be deficient in digestible protein, a
small amount of some food containing a liberal supply of
this nutrient may be added. Finally, when the require-
ment as to amounts of nutrients is satisfied, the various
other factors as bulk, suitable combinations, cost, and
labor involved in preparation are to be considered.

Example. — Calculate a ration for a dairy cow. The standard
ration calls for 1.8 to 2 pounds digestible protein and from 10 to
12.5 pounds digestible carbohydrates. It is necessary to combine
the coarse fodders and grains so as to secure approximately these
amounts of nutrients. A trial ration is calculated, composed of 10
pounds each of clover-hay and corn fodder, 20 pounds of mangels,
5 of bran and 3 of oats. The digestible nutrients in these materials,
as given at the close of the chapter, are as follows :
Digestible Nutrients.

Carbohy-
Protein. Fat. drates. etc.

Wheat bran 12.9 3.4 40.1

Mangel beets i.i o.i 5.4

Clover hay 6.8 1.7 35.8

Corn fodder 2.5 1.2 34.8

Oats 9.2 4.2 47.3

These figures are on the basis of 100 pounds. The

RATIONAL FEEDING OF ANIMALS 357

amounts of nutrients in one pound are found by moving
the decimal point two places to the left. Multiplying
the pounds of food by the per cent, of digestible nutri-
ents, the pounds of digestible nutrients will be found to
be as follows :

Pounds of Digestible Nutrients.

Pounds. Protein. Fat. Carbohydrates, etc.

loCloverhay 0.68 0.17 3.58

10 Corn fodder 0.25 0.12 3.48

20 Mangel-wurzels . 0.22 0.02 1.08

5 Bran 0.64 0.16 2.00

3 Oats 0.28 0.13 1.42

2.07 0.60 11.56

Compared with the standard ration, it will be observed
that the amounts of nutrients are approximately as given
in the table, suggesting that as far as total nutrients are
concerned, the ration is a reasonable one. The coarse
fodder, grain, and roots are about in the proportions
given in Section 477, As to the effects of the various
foods, the bran, mangels, and clover hay might possibly
prove somewhat laxative in character, and while the
ration supplies all of the requisites, as dry matter and
amount of nutrients, it would be necessary to note the
effect upon the animal, before concluding that it was sat-
isfactory in all respects.

481. Nutritive Ratio. — The nutritive ratio is the ratio
which exists between the digestible protein and the di-
gestible non-nitrogenous compounds. A nutritive ratio
of I to 6.7 means that for every i pound of crude pro-
tein there are 6.7 pounds of digestible non-nitrogenous
compounds. A wide nutritive ratio means a large

358 AGRICULTURAL CHEMISTRY

amount of non-nitrogenous to nitrogenous compounds,
while a narrow nutritive ratio means a small amount of
non-nitrogenous to nitrogenous compounds.

To calculate the nutritive ratio, first determine the
pounds of digestible protein in the food used, then the
pounds of digestible carboh5'drates, etc. Multiply the
pounds of digestible ether extract by 2.2 because the fat
produces 2.2 times as much heat, consequently is con-
sidered 2.2 times more concentrated than the nitrogen-
free extract compounds. Add the digestible fiber, nitro-
gen-free extract and corrected ether extract and divide
the sum by the digestible protein; the result is the nutri-
tive ratio. The nutritive ratio of the ration given is 6.57
(0.6 X 2.2 = 1,32) (1.32 + 11.56 = 12.88) (12.88^2.07
= 6.02).

482. Caloric Value of Rations. — The caloric value of
a ration is determined by multiplying the pounds of
digestible ether extract by the factor 4225 and adding this
to the number secured by multiplying the sum of the di-
gestible protein and carbohydrates by i860. As used in
the calculation of rations, the carbohydrates include the
nitrogen-free extract compounds and the digestible fiber.
The term carbohydrates is used in the broad rather than
the restricted sense.

Problem /.—Calculate a ration for a 1200-pound horse at light
work. Use any foods desired.

Problem 2. — Calculate a ration for a 1200-pound horse at heavy
farm labor.

Problem 3. — Calculate a ration for a pig weighing 100 pounds.

Problon 4. — Calculate a ration for a pig weighing 250 pounds.

RATIONAI, FEEDING OF ANIMALS 359

Problem 5— Calculate a ration for a dairy cow giving a full flow
of milk.

Problem 6. — Calculate a dairy ration for av-erage milk yield.

Problem 7. — Calculate a ration for a sheep weighing 100 pounds.

Problem 8. — Calculate a ration for a growing steer weighing 500
J)Ounds.

Problem g. — Calculate a ration for a 1200-pound steer, fattening
period.

483. Comparative Cost and Value of Grains. — The

market value of grains frequently differs from their actual
food value. That is, a given sum of money if invested
in one food article will often procure a larger amount of
digestible protein and other nutrients than if invested in
other foods. To illustrate : If corn is 50 cents and oats
30 cents per bushel, $1.00 will purchase either- 11 2 pounds
of corn or 107 pounds of oats. Which is the cheaper and
more valuable for feeding purposes ? The digestible
nutrients in 100 pounds of corn and oats are as follows :

Digestive nutrients. Pounds per hundred.

Protein. Fat. Carbohydrates, etc.

Corn 7.9 4.3 66.7

Oats 9.2 4.2 47.3

The amounts of digestible nutrients in 112 pounds of
corn and 107 pounds of oats obtained by multiplying by
the per cent, of digestible nutrients are :

Pounds. Protein. Fat.

Carbohy-
drates. Calories.

Corn ..

112 8.85 4.82

74.7 175,684

Oats-..

107 9.84 4.50

50.6 13^,407

There is

a difference of about

I pound of digestible

protein in favor of the oats and 24 pounds of digestible
carbohydrates in favor of the corn; the dollar's worth of

360 AGRICUI.TURAI, CHEMISTRY

corn would also contain about 44,000 more calories. At
the prices given, corn rather than oats would more eco-
nomically form the larger portion of a grain ration for
work-horses, beef and dairy animals, and swine and sheep.
For growing animals, however, a large amount of corn
is not desirable.

In deciding the comparative value of foods on the basis
of their nutrient content, preference should usually be
given to the protein, but when the difference in digestible
protein is small, the preference should be given to the
food containing the largest amount of available carbo-
hydrates and number of calories. Comparisons between
foods which are too unlike in character of nutrients can-
not safely be made. It is not possible to assign an abso-
lute value to any food upon the basis of any one or all
of its digestible nutrients, because the comparative value
of the different nutrients has not, as yet, been definitely
ascertained. In the selection of foods, it will frequently
be found that a given sum of money can best be invested
in the purchase of two foods, one nitrogenous and the
other non-nitrogenous, rather than in the purchase of
one. The results of actual feeding standards should also
be considered before definitely selecting foods. When
both the available nutrients and the results of feeding ex-
periments are considered, an accurate idea of the compara-
tive cost and value of grains and milled products can be
formed.

Problem. — Complete the followiug table and calculate the avial-
able nutrients and calories that can be procured for f i when the
various foods are at different prices. In making the calculations.

RATIONAL FEEDING OF ANIMALS

361

use the prices of your local or home market. Select three of the
cheapest and three of the most expensive foods from the list.

Price

per

bushel

or ton.

Pounds

forfi.oo.

Nutrients procurable for $1.00.
Pounds digestible nutrients.

Protein.

Carbohy-
drates.

Ether
extract.

Calories.

Corn

Oats -

Barley

Wheat

" bran

" shorts ..

Oil meal

Linseed meal . . .

Cottonseed meal

Gluten meal

484. Sanitary Conditions.— Satisfactory results in the
feeding of animals can be secured only under the best
sanitary conditions. When animals are kept in crowded
quarters, deprived of pure air and sunlight, they fail to
make the best use of the food consumed. Carbon dioxid
thrown off from the lungs and ammonia produced from
decaying manure form ammonium carbonate, a volatile
and irritating compound. Sunlight is an important fac-
tor for promoting animal growth. Experiments with
growing calves have shown that under the same condi-
tions of feed and management, animals reared with an
abundance of sunlight make better gains in weight, and
are more vigorous than those confined in dark quarters.
The best results are obtained in the feeding of animals

362 AGRICUI^TURAIv CHEMISTRY

when their surroundings are most sanitary. A large
amount of available energy is often lost in warming up
cold, wet bedding. Pure water, pure air, sunlight, clean
quarters and dry bedding are as necessary to animals as is
a well-balanced ration.

Table of Feeding Standards.

Per 1000 lbs. live weight, daily.
Digestible organic substances.

Dry Car-
sub- Pro- bohy- Nutri-
stance. tein. drates. Fat. Total. tive
Kind of animal. lbs. lbs. lbs. lbs. lbs. ratio i:

Fattening bovities 30 2.5 15. 0.5 18. 6.5

Milk cows :

Daily milk yield, II lbs .. . 25 1.6 10. 0.3 11. 9 6.7

Daily milk yield, 16 V2 lbs . 27 2. 11. 0.4 13.4 6.

Daily milk yield, 22 lbs .. . 29 2.5 13. 0.5 16. 5.7

Daily milk yield, 27V2 lbs . 32 3.3 13. 0.8 17. i 4.5

Sheep 22 1.3 II. 0.3 13.5

Fattening sheep, first period 30 3. 15. 0.5 18.5 5.4

Horses :

Light work 20 1.5 9.5 04 11. 4 7.

Moderate work 24 2. 11. 0.6" 13.6 6.2

Severe work 26 2.5 13.3 0.8 16.6 6.

Fattening swine :

First period 36 4.5 25. 0.7 30.2 5.9

Second period 32 4. 24. 0.5 28.5 6.3

Third period 25 2.7 18. 0.4 21. i 7.

Growing cattle (dairy breeds).

Age in I,ive weight
months, per head, lbs.

2- 3 150 23 4. 13. 2. 21. 4.5

3- 6 300 24 3. 12.8 I. 16.8 5.1
6-12 500 27 2. 12.5 0.5 15. 6.8

12-18 700 26 1.8 12.5 0.4 14.7 7.5

18-24 900 26 1.5 12. 0.3 13.8 8.5

RATIONAL, FEEDING OF ANIMALS

363

Per 1000 lbs. live weight, daily.
Digestible organic substances.

Kind of animal.
Age in
months.

Beef breeds :

2- 3

3-6

6-12

12-18

18-24

Sheep :

lyive weight
per head, lbs.

Dry-
sub- Pro-
stance, tein.
lbs. lbs.

Swine :

4- 6
8-1 1

2- 3

3- 5
5-6

65
100

45
no

150

23
24
25
24

24

26
24

44
35
33

4.2

3-5

2.5

2.

1.8

4.4
3-0

7.6
5-0

4-3

Car-
bohy-
drates.

lbs.

13-

12.8

13.2

12.5

12.

15-5
14-3

2S.0
23.1
22.3

Fat.
lbs.

0.9
0.5

i.o
0.8
0.6

Total.

lbs.

19.2
17.8
16.4

15-
14.2

20.8
17.8

35-7
28.9
27.2

Nutri-
tive
ratio i:

4.2

4-7
6.
6.8
7.2

4-
5-2

4.0
5-0
5-5

DiGESTiBi,E Nutrients in Fodders.

Digestible nutrients in 100 lbs.

Dry matter Carbohy- Ether

Name of feed. in 100 lbs. Protein. drates. extract.

Corn (all analyses) 89.1 7.9 66.7 4.3

Dent corn 89.4 7 8 66.7 4.3

Flint corn 88.7 8.0 66.2 4.3

Sweet corn 91.2 8.8 63.7 7.0

Corn cob 89.3 0.4 52.5 0.3

Corn and cob meal 84.9 4.4 60.0 2.9

Corn bran 90.9 7.4 59.8 4.6

Gluten meal 91.8 25.8 43.3 11. o

Germ meal 89.6 9.0 61.2 6.2

Hominy chops 88.9 7.5 55.2 6.8

Wheat 89.5 10.2 69.2 1.7

Wheat bran 88.1 12.2 39.2 2.7

Wheat bran (spring wheat) . 88.5 12.9 40.1 3.4

Wheat bran (winter wheat) . 87.7 12.3 37.1 2.6

364

AGRICUI.TURAL CHEMISTRY

Dry matter
Name of feed. in 'loo lbs.

Wheat shorts 88.2

Wheat middlings 87.9

Wheat screenings 88.4

Rye 88.4

Rye bran 88.4

Rye shorts 90.7

Barley 89. i

Malt sprouts 89.8

Brewers' grains ( wet) 24.3

Brewers' grains (dried) 91.8

Oats 89.0

Oat feed or shorts 92.3

Oat hulls 90-6

Buckwheat 87.4

Buckwheat bran 89.5

Flax seed 90-8

Linseed meal (old process). 90.8

Linseed meal (new process). 89.9

Cottonseed meal 91.8

Coarse Fodders.

Fodder corn (green) 20.7

Fodder corn (field-cured) • . . 57.8
Corn stover (field-cured) 59.5

Fresh Grass.

Pasture grasses (mixed) 20.0

Kentucky blue grass 34.9

Timothy, different stages--. 38.4

Oat fodder 37-8

Peas and oats 16.0

Hay.

Timothy 86.8

Redtop 91. 1

Kentucky blue grass 78.8

Digestible

nutrients in

100 lbs.

Protein.

Carbohy-
drates.

Ether
extract

12.2

50.0

3-8

12.8

53-0

3-4

9.8

51.0

2.2

9-9

67.6

I.I

II-5

50.3

2.0

II. 9

45-1

1.6

8.7

65.6

1.6

18.6

37-1

1-7

3-9

9-3

1.4

15-7

36.3

5-1

9.2

47-3

4.2

12.5

46.9

2.8

1-3

40.1

0.6

7-7

49-2

1.8

74

30-4

1-9

20.6

17.1

29.0

293

32.7

7.0

28.2

40.1

2.8

37-2

16.9

12.2

i.o

II. 6

0.4

2.5

34-6

1.2

1-7

32.4

0.7

2.5

10.2

0-5

30

19.8

0.8

1.2

19.1

0.6

2.6

18.9

1.0

1.8

7-1

0.2

2.8

43-4

1.4

4.8

46.9

1.0

4.8

37-3

2.0

RATIONAL FEEDING OP ANIMALS

365

Digestible nutrients in 100 lbs.

Dry matter
Name of feed. in 100 lbs.

Hay (continued).

Hungarian grass 92.3

Mixed grasses 87.1

Rowen (mixed) 83.4

Oat hay 91.1

Straw.

Wheat 90.4

Oat 90.8

Fresh Legumes.

Red clover, diff. stages 29.2

Alsike, bloom 25.2

Crimson clover 19. i

Legume, Hay and Straw.

Red clover, medium 84.7

Red clover, mammoth 78.8

Alsike clover 90.3

Alfalfa 91.6

Cow pea 89.3

Silage.

Corn o 20.9

Roots and Tubers.

Potato 21. 1

Sugar-beet 13,5

Mangel beet 9. i

Rutabaga 1 1 .4

Carrot 11.4

Miscellaneous.

Pumpkin ( field ) 9.1

Beet-pulp 10.2

Cow's milk 12.8

Skim milk (gravity) 9.6

Skim milk (centrifugal) 9.4

Buttermilk 9.9

Whey 6.6

Protein.

Carbohy-
drates.

Ether
extract.

4-5

51-7

1-3

5-9

40.9

1.2

7-9

40.1

1-5

4-3

46.4

1-5

0.4

36.3

0.4

1.2

38.6

0.8

2.9

14.8

0.7

2.7

I3-I

0.6

2.4

13-9

0.5

6.8

35.8

1-7

5-7

32.0

1-9

8.4

42.5

1-5

II. 0

39-6

1.2

16.8

38.6

I.I

0.9

II-3

0.7

0.9

16.3

0.1

I.I

10.2

0.1

I.I

5-4

0.1

I.O

8.1

0.2

0.8

7.8

0.2

I.O

5-8

0-3

0.6

7-3

3-6

4.9

3-7

3-1

4-7

0.8

2.9

5-2

0.3

3-9

4.0

I.I

0.8

4-7

0-3

CHAPTER XXXVII
Composition of Animal Bodies

485. Water and Dry Matter.— About half of the live
weight of an animal is water. In fat animals, the pro-
portion of water is less than in lean animals. The same
general classes of organic compounds present in plants,
as non-nitrogenous and nitrogenous, are also present in
animal bodies ; the animal forms, however, are usually
somewhat more complex than the plant forms. Animal
bodies are characterized by containing a high per cent, of
fat and proteid materials and a low per cent, of non-
nitrogenous compounds other than fat.

486. Mineral Matter. — The ash elements in the animal
body are the same as those found in plants, and are
nearly all furnished from vegetable sources. The body
of an animal, live weight basis, contains from 2 to 4 per
cent, of mineral matter, from a half to three-fourths of
which is present in the bones, while the remainder is pres-
ent both in solution in the various fluids, as the blood,
chyle, etc., and deposited and combined with the solid
and fleshy tissues of the body. Silicon in animal bodies
is found mainly in the hair, wool and feathers. Sodium
and chlorin, while unnecessary to plants, are absolutely
necessary to animals. A thousand parts of blood yield
about 4 parts of mineral matter, of which 1.2 are
sodium chlorid. In the blood, salt is necessary as a sol-
vent for the proteids.

The per cent, of ash in the carcasses of different ani-

COMPOSITION OF ANIMAL BODIES 367

mals varies, being greatest in the half-fatsteer or ox, and
least in the fat pig. In the process of fattening, the per-
centage amount of ash is decreased.

As in the case of the plant, the mineral matter of the
animal body must be secured and assimilated in the early
stages of growth. Young pigs, or other young animals,
fed exclusively on a food which like corn is poor in digesti-
ble mineral matter, have bones which are weak and do
not furnish a framework strong enough for the perfect
development of the body in its last stages of growth.
The same elements which are essential for plant growth
are also essential for animal growth.

487. Fat. — The per cent, of fat in the carcass of ani-
mals ranges from 14 to 45 per cent, of the live weight.
The carcasses of fattened steers of good quality consist
of about one-third fat ; in moderately fat sheep there is
somewhat more, while the
largest amount is present in
the body of the very fat pig,
with the very fat sheep as a
close competitor. " It is thus
seen that animal food of re-
puted high quality as sold by
the butcher, and to v/hich beef- •
such a highly nitrogenous -i^ound-
character is usually attributed, ^'^- 99.-composition of meat,
will consist of fat to the extent of one-third to one-half
of its total weight." (I^awes & Gilbert.)

488. Nitrogenous Matter is present to the extent of
10 to 18 per cent, in the live animal, being least in the very

368 AGRICULTURAL CHEMISTRY

fat pig and most in the half-fat ox. The offal parts, as
the head, feet, tail, hair, wool, and horns, are quite rich
in nitrogen but not so rich as the flesh. Beef-yielding
animals, on the whole, contain rather more nitrogenous
compounds than sheep, which in turn contain more than
pigs. A large amount of the nitrogenous compounds of
sheep and lambs is present in the wool (50 to 55 per
cent). About 75 per cent, of the carcass of the sheep is
consumed as food ; thus it will be seen that much less
than half of the total nitrogen is really made use of as
human food. Of the fattened pig, about three-fourths of
the nitrogenous compounds are in the edible carcass.
From 6 to 7 parts are in the bone, and about one- quarter
is in the offal. About 8 per cent, of the nitrogenous
compounds of the offal and a little over three- fourths of
the total nitrogenous compounds of the pig are consumed
as food. About two-thirds of the entire nitrogen of the
calf and steer are in the butcher's carcass, and about
12 per cent, is in the bones. From 5 to 7 per cent, of
the nitrogen of the offal parts and about 60 per cent, of
the total nitrogen of the steer are utilized as human food.
In the table of relative composition of animal bodies,
it will be noted that the mineral matter increases and de-
creases with the nitrogenous matter. In the carcasses of
all animals, it will be observed that the amount of fat al-
ways exceeds the amount of nitrogenous matter, except
in the case of the lean calf. In the bodies of animals in
good condition, there is usually twice as much fat as dry
protein. The following table is from the extensive work
of lyawes and Gilbert.

COMPOSITION O^ ANIMAI^ BODIES

369

^^'^W^K'^'^^W^

o ^ S- PL o

•t3 n>

p tf

►- o

rtl J* 1^

f- > 1

W KJ K) OJ -fi -t^ Ck)

ii.ai*-J4i^ mO-" 0\ Cn 'j^ -i-^ ^

O i-t in \D 0\ \D

■>" f^ o ^'

CO as S o

On M M^OJ CO^O OOONOsr*

(J\ ^ CTs On Cn
11 ^ -^ O O
^ -^l O '

-P>- Cn Cn

N) n -f^ Os OJ PJ

n-<

BO

00 o> ^J +>. -P. o -^

po Cn
C7\ b^

M

K>

M

w

OJ

OJ

K3

00

-P^

00

>

ON
01

0\

^

00

M
^

ON -t-

10

S^

00

0

a
0

t.

0

Oj

0

w

■f^

-P-

(0

-t^

0\ Cn

3

^D

^

^

w

0

00 oj

Cn

ON

M

0

*>
10

to

Cn

00

Cn Oj

a\ cn

M

CO

00
Cn

P

M

M

00

Cn
Cn

1-1

Cn
lo

4^

Cn

P

Is}

Cn

4^
00

Cn

Cn
Cn

OS

b

to

►1

0

»

3

3

C/i

ON

Cn ^

p p

ON -^I

ON Oj

4^
00
Cn

P
00

00

B
n

0

24

370 AGRICULTURAL CHEMISTRY

489. Proteids of Meat.— I,ean meat, fat-free, is a con-
centrated nitrogenous material composed mainly of pro-
teids but containing also small amounts of amides, albu-
minoids and in some cases, alkaloidal bodies. The pro-
teids are present mainly, in insoluble forms ; a small
amount, however, is soluble. The principal soluble meat
proteids are albumin and syntonin.

490. Albumin. — The formula C^HugNigSO^j has been
tentatively assigned to albumin. The amount of albu-
min in meats ranges from 0.6 to 5 per cent. Liebig gives
as a mean 2.96 per cent. The lean meat of the pig as
well as that of poultry contains a relatively large amount.
Albumin is soluble in cold water, and is coagulated at a
temperature of 157° to 163° F. and of 69° to 75° C.
Dilute acids convert albumins into acid albuminates while
alkalies produce alkali .albuminates. The albuminates
are proteids derived from albumins and other proteids
by the action of acids or alkalies.

491. riyosin. — Myosin is obtained from meat by extrac-
tion with a weak solution of common salt. The myosin
dissolves in the salt solution and is precipitated by heat
and chemicals (see Experiments 60 and 61). Myosin is
a globulin and in the living animal is present largely in
soluble forms.

492. Syntonin has the same general relationship to
myosin as dextrin has to starch. Dextrin is derived
from starch and syntonin is derived from myosin. Syn-
tonin is an acid albuminate formed by the action of dilute
acids*. The amount of syntonin and myosin in meats is

COMPOSITION OF ANIMAI. BODIES 37 1

small, never exceeding, according to Hoffman, 2 or 3 per
cent.

493. Hemoglobin. — When fresh meat is soaked in cold
water, the solution becomes red in color on account of the
hemoglobin which is extracted. Hemoglobin is a pro-
teid which imparts the red color to the blood and is coag-
ulated by heat at a temperature of 128° to 132° F.
There is a sufficient amount of various salts in the
blood to dissolve some of the fibrin proteids which are
precipitated at a temperature of about 140° F. or 60° C.

494. Insoluble Proteids — The larger portion of the
nitrogenous material of the muscles is in the form of in-
soluble muscular fiber. From 90 to 95 per cent, of the
total nitrogenous matter of fat-free lean meat is present
in soluble forms. In the grains, various insoluble pro-
teids are found and in the different meats different kinds
of insoluble proteids are present. Meats differ both as
to the kinds and proportional amounts of the several
proteids which they contain.

495. Peptones. — When muscular fiber is acted upon
by some ferments, peptones are produced. Only a small
amount of peptones is present in meat. When meat is in
cold storage to undergo the curing process before it is
placed upon the market, the peptonizing process takes
place to a slight extent. If the process is too long con-
tinued, ptomains, which are poisonous compounds, may
develop. When meat of the best quality is produced,
long curing is unnecessary,

496. Keratin is an amide compound present in meat

372 AGRICULTURAL CHEMISTRY

juices in small amounts; loo pounds of meat contain from
0.07 to 0.32 of a pound. Like other amides, it pos-
sesses less food value than protein. Keratin, sarkin
and allied bodies are not coagulated by heat, but
are gradually decomposed and give off characteristic
odors when meat is being cooked. Keratin and sarkin
are present in large amounts in beef extracts and although
they possess no direct food value, they impart palatabil-
ity and are mainly valuable on this account.

497. Albuminoids, Gelatin. — When bone or muscular
tissue is subjected to the action of boiling water,
gelatin separates upon cooling and standing. Gelatin
is quite different in chemical composition from albumin,
muscular fiber and other proteids. Hoff meister gives the
formula as Cio^Hj.jOjg. It contains no sulfur, while pro-
teids contain from i to 2 per cent. Gelatin may prevent
the rapid depletion of the protein of the body but cannot
take its place as a nutrient. The approximate amounts
of the nitrogenous compounds in lean meat are given in
the following table from which it will be observed that
only a small part is present in the meat juices.
The Nitrogenous Compounds oe Meat.

Per cent.

f Muscular fiber 12 to 18

1 Albumin 0.5 to 2.0

^- P'-^teids iMyosin 0.4 to 0.6

{ Syntonin

2. Albuminoids Gelatin, etc 2.0 to 5.0

f Keratin 0.07 to 0.34

3. Amides I Sarkin o.oi to 0.03

lurea

4. Alkaloids (ptomaines) Occasionally traces.

COMPOSITION OF ANIMAL BODIES 373

498. Influence of Food upon the Composition of Ani-
mal Bodies. — The nature of the food consumed has a
noticeable effect upon the composition of the animal body.
The food affects both the amount of meat produced and
its composition. As a general rule, an unbalanced ration,
particularly one with a large amount of non-nitrogenous
compounds, produces flesh that is poor in circulatory pro-
teids. But few systematic experiments have been made
to study the influence of food upon the composition of
animal bodies.

499. Composition of the Human Body. — Halliburton
States that the human body contains 58.5 per cent, water.
The amount at different stages of life varies; in later life,
the body contains less than during youth. Water is
present in all parts of the body ; enamel contains 2 per
cent., the gray matter of the brain 85 to 86 per cent.,
bone about 50 per cent., and muscle 75 per cent. The
amount of fat varies between quite wide limits; normally,
Moleschott states that it makes up from 4 to 5 per cent,
of the weight of the body. Adipose tissue contains about
85, marrow 96, and nerves 22 per cent. fat. Twenty-
five percent, of the muscle is solid matter, of which 21
per cent, is proteid and albuminoid material, and 4 per
cent, is fat and nitrogenous extractive bodies. Mineral
matter is present in small amounts combined with the
muscular and other tissues and in solution in the various
fluids and secretions.

CHAPTER XXXVIII
Rational Feeding of Men

500. Similarity in the Principles of Human and Ani-
mal Feeding. —The rational feeding of men is founded
upon the same principles as the rational feeding of ani-
mals. It is the object in each case to supply the body
with the right kinds and amounts of nutrients to meet
all of its demands. It is not possible in either human or
animal feeding to establish inflexible standards.

501. Dietary Standards. — The standard rations which
have been proposed by Atwater, Voit and others call for
about one- fourth of a pound each of fat and protein and
a pound of carbohydrates in the ration of a man at aver-
age muscular labor. Such a ration should yield about
3,200 calories. The actual amount of nutrients consumed
by laborers does not always conform to this standard.
For example, studies have shown that the negro laborer
in the South often, by choice, consumes less than o.i
pound per day of protein, while a well-fed mechanic fre-
quently consumes over 0.5 pound per day. While only
tentative standards are proposed, experiments and
dietary studies have shown that the best results are ob-
tained in the feeding of men, as in the feeding of ani-
mals, when the ration conforms within reasonable limits
to the standard. By a dietary standard is meant the
approximate amount of nutrients which the dail}^ ration
should contain. Such a standard as proposed by Atwater
is as follows :

RATIONAL FEEDING OF MEN 375

Carbohy- Fuel Nutri-

Protein. Fat. diates. value. live

lb. lb. lbs. calories, ratio.

Man with little physical exercise. 0.20 0.20 0.66 2450 5.5

Man with light muscular work •• 0.22 0.22 0.77 2800 5.7

Man with moderate muscular work 0.28 0.28 0.99 3520 5.8

Man with active muscular work. . 0.33 0.33 i.io 4060 5.6

Man with hard muscular work .. 0.39 0.55 1.43 5700 6.9

502. Amount of Foods Consumed per Day. — In com-
bining foods to form human rations, there should be, as
in animal rations, a variety of foods and no food article
should be used in excessive amounts. The approximate
amounts of food consumed per day by a man at average
labor, are as follows :

Range. Average.

Ounces. Pound.

Bread 6 to 14 0.50

Butter 2 to 5 0.12

Potatoes 8 to 16 0.75

Cheese i to 4 0.12

Beans i to 4 0.12

Milk 8 to 32

Sugar 2 to 5 0.20

Meat 4 to 12 0.25

Oatmeal ito 4 0.12

In a balanced ration, it is the aim to obtain from all of
the foods approximately 0.25 pound each of fat and pro-
tein and a pound of carbohydrates. In case of severe
work, larger amounts of nutrients, as indicated in the
table, are necessary. The composition of human foods
is given in the tables at the close of the chapter.

In calculating the amounts of nutrients in fractions of
a pound, the percentage composition of the food is mul-
tiplied by the weight used, as in calculating animal ra-
tions (see Section 480).

376 AGRICULTURAL CHEMISTRY

503. Calculating a Balanced Ration. — The various
articles of food should be selected according to cost,
nutritive value, purposes for which they are desired,
amount and kind of work to be performed, and individual
preferences. When bread, butter, milk, potatoes, sugar,
oatmeal, cornmeal, beef, ham and eggs, are to be com-
bined to form a ration, such amounts are taken as will
yield approximately 0.25 pound each of protein and fat,
and a pound of carbohydrates. Such a combination
would be as follows :

Nutrients.

Amount Carbohy-

per day. Protein. Fat. drates.

Foods. Ounces. Pound. Pound. Pound. Calories.

Ham 4 0.04 0.09 480

Eggs (2) 0.03 0.02 136

Bread • . • '. 8 0.05 o.oi o. 28 650

Butter 2 o.ir 450

Potatoes 12 0.02 0.14 285

Milk 16 0.04 0.04 0.05 325

Sugar 2 0.12 200

Oatmeal 2 0.02 o.oi 0.09 230

Beef (stew) 4 0.04 0.05 250

Cornmeal 4 0.02 o.oi 0.18 420

0.26 0.34 0.86 3426

This ration contains 0.26 pound protein, 0.34 pound
fat, 0.86 pound carbohydrates and yields 3,426 calories.
While it contains somewhat more fat and slightly less
carbohj'drates than the standard, it is suflSciently near
the standard for all practical purposes. Some vegetables
and fruits should be added to the ration not so much
with the object of increasing the nutrients as for the pur-
pose of greater variety and palatabUity. In this ration,

RATIONAL FEEDING OF MEN

377

the nutrients are secured from a variety of sources, the
largest amount of protein coming from the bread.
About one-third of the protein is supplied in the form of
meat, one- fourth by the eggs and milk, while the balance
is secured from the vegetable foods. Bread, potatoes,
cornmeal and sugar supply most of the carbohydrates,
the two ounces of sugar supplying nearly 14 per cent.

In combining foods to form balanced rations, meats,
beans, cheese, milk, bread and oatmeal supply protein,
while pork, ham, bacon and other fat meats, butter,
cheese and milk supply the f£.ts. Carbohydrates are
supplied more liberally from bread, rice, cornmeal,
cereals, potatoes, sugar and vegetables.

504. Comparative Cost and Value of Foods. — With
human as with animal foods, the market price does not,
as a rule, correspond with their nutritive value. When
foods differ widely in cost, their relative values can be

f\T.13

MILK t^*T CHEESE

Fig. 100. — Comparative composition of milk, cheese, and butter.

approximateb' determined by comparing the amounts of

378 AGRICULTURAL CHEMISTRY

nutrients which a given sum of money will procure in
each case. The principle is the same as in the compari-
son of cost and value of animal foods, Section 483.

In making comparisons, preference cannot be given to
any single nutrient. In general, however, foods which
supply the largest amount of protein for a given sum of
money are cheapest and most economical provided there
is no great difference in the amounts of fat and carbohy-
drates. When there is but little difference in protein
content, preference should be given to foods yielding the
largest number of calories.

In order to calculate the nutrients which can be pro-
cured for a given sum of money, first determine the
pounds of food, then multiply the weight by the percent-
age composition, using the figures in the tables.

When round steak is 15 cents per pound and milk 5
cents per quart, the amounts of nutrients which can be
purchased for 1 5 cents are as follows :

15 cents will buy

Carbo-
Protein. Fat. hydrates,
lbs. lb. lb. lb. Calories.

Round steak i 0.18 0.12 870

Milk 6 0.21 0.24 0.30 1950

Three quarts of milk or six pounds contain 0.03 pound
more protein and 0.12 pound more fat and yield over
1,000 calories more than a pound of round steak costing
the same. Milk at 5 cents per quart should be used lib-
erally in the ration when steak is 15 cents or more per
pound. It does not follow that meat should be entirely
excluded from the ration in favor of milk but the

RATIONAL FEEDING OF MEN 379

nutrients indicate that milk should be used in liberal
amounts.

Problem i. — Calculate a balanced ration for a man at hard mus-
cular labor and give the cost of the food articles required.

Problem 2. — Calculate a ration for a man with little physical ex-
ercise, giving cost of ration.

Problem j. — Calculate the amounts of food and the nutrients re-
quired for a family of seven for ten days, three of the family to be
considered as consuming each 0.8 as much as an adult. Calculate
the cost of the food. Then calculate, on the same basis, the prob-
able amounts of food for one year with cost, adding 20 per cent,
additional for fluctuations in market prices and foods not included
in the ten-day list.

Problem 4. — How do beef and mutton compare as to nutrients
when they are the same price per pound ?

Problem 5. — Calculate the comparative amounts of nutrients that
can be procured when cheese is 16 cents and loin steak 20 cents
per pound, and also when cheese is 20 cents and loin steak is 16 cents.

Problerii 6. — How do the nutrients in chicken at 12 cents per
pound compare with those in round steak at 14 cents per pound?

Problem 7. — How does flour at 2 cents per pound compare in
nutritive value with a cereal breakfast food at 10 cents per pound,
and having the same composition as whole wheat?

505. Factors Influencing Digestibility. — The factors,
discussed in Chapter XXXV, which influence the digesti-
bility of animal foods also influence the digestibility of hu-
man foods. The mechanical condition of the food and the
method of preparation have a more pronounced effect in
a human than in an animal ration. The term digesti-
bility has, by some physiologists, been used to designate
ease of digestion rather than completeness of the process,
foods which are easily digested and require but little

380 AGRICULTURAI, CHEMISTRY

work of the digestive tract being termed digestible, while
those which require a larger amount of work are said to
be indigestible. Some confusion has arisen from this use
of the term digestible. For example, rice is frequently
called a digestible food and cheese an indigestible food.
Digestion experiments have shown that cheese is more
completely digested than rice. A food which is easily
digested is not necessarily completely digested.

Individuality influences the digestibility of foods to a
marked extent. For example, digestion experiments
have shown a difference of over 14 per cent, in diges-
tibility of the protein in a mixed ration composed of
bread, milk and beans. There is a greater difference
between individuals as to the ease of digestion than as to
the completeness. Since digestion is largely a biochemical
process, its completeness is necessarily influenced by
the activity of the cells in the digestive tract. The com-
bining of foods influences digestibility. For example,
milk in a ration exerts a favorable influence upon the di-
gestibility of the other foods with which it is combined.
This is because of the presence in milk of' enzymes or
soluble ferments. Experiments have shown that 12.5
per cent, of the protein in a sterile food, as toast, is capa-
ble of being digested by the soluble ferments of milk.
■ The method of cooking and preparing foods also exerts
an influence upon their digestibilitj'. Cooking changes
both the physical and chemical composition of foods.
The cell walls of vegetables and cereals are broken and
the starch granules ruptured, thus exposing them to
more thorough action of the digestive fluids. Cooking

RATlONAIy FEEDING OF MEN 38 1

influences the ease or rapidity of digestion to a greater
extent than it does the completeness of the process. The
carbohydrates are favorably influenced by the action of
heat while, in some cases, prolonged heat may make the
proteids less digestible. In pasteurized milk, for example,
the proteids are slightly less digestible than in pure fresh
milk, while in sterilized milk, the digestibility is notice-
ably lessened. As in the case of animals, the mechanical
condition of a food influences both the ease and the
completeness of the process. With persons of sedentary
habits, the best results are secured when a small amount
of some coarsely granulated food is present. A large
amount of such foods, however, is not suitable in the
ration of a hard working man because of lack of avail-
ability of the nutrients.

506. Requisites of a Ration.— Reasonable combina-
tions should be made in forming balanced rations. A
number of foods which are slow of digestion or require
much intestinal work should not be combined. Neither
should a number of foods which are easily digested and
leave but little indigestible residue. Two foods which
are either laxative or costive should not be combined.
After formulating a ration, it should be critically ex-
amined to see if it satisfies the following conditions : (i)
Foods economical and suitable to the work to be per-
formed, (2) foods combined so as to secure balanced work
of the digestive tract, (3) foods not too laxative or too cos-
tive in effect, (4) requisite bulk, (5) sufficient amount of
indigestible residue to dilute the waste products in the
intestinal tract.

3^2 AGRICULTURAL CHEMISTRY

507. Dietary Studies. —A dietary study considers the
cost and amount of nutrients consumed by individuals
and families. It is an investigation in which men are
used and human foods are studied instead of farm ani-
mals and animal foods. Dietary studies have shown that
frequently money is injudiciously spent in the purchase
of high-priced foods which contains but a small amount
of nutrients. In a dietary study, the amounts of nutri-
ents in the foods exclusive of the refuse parts are deter-
mined. From the weight of the foods, the nutrients
contained are calculated using the tables, or thej' are
determined by chemical analysis.

The purchasing of food is frequently done without re-
gard to nutritive value. Erroneous ideas as to the
value of foods are often the cause of extravagance in
their purchase and use. As for example, it has been
claimed that the banana is as valuable as beef, and mush-
rooms have been erroneously called vegetable beefsteak.
Many other foods are assigned fictitious values. Too
frequently, choice is made on the basis of palatability, but
cost of nutrients and kind of work to be performed should
be considered as well as palatability. Dietary studies of
•the United States Department of Agriculture have shown
that lack of knowledge in regard to the value of foods
has frequently resulted in whole families being underfed,
not from necessity but from lack of judgment in the se-
lection of foods. While it is not practicable or desirable
to confine the ration to an absolute standard, dietary
studies have shown that for long periods the best results
are obtained when foods are combined so as to secure nu-

RATIONAL FEEDING OF MEN

383

trients in approximately the amounts given. By means
of a careful study of the dietary, it is possible to reduce
the cost of food without impairing its nutritive value,
and in many cases, as the cost is decreased, the nutritive
value is increased.

508. Chemical Changes in the Cooking of Foods. — The
chemical changes which take place in cooking are brought
about by the joint action of heat, water and ferments and
occasionally by the use of chemicals. The various com-
pounds of which foods are composed, namely, carbohy-
drates, proteids and fats, are all susceptible to the action of
these agencies and the chemical changes which they un-
dergo are briefly discussed in Chapters XXIII and XXIV,
treating of the composition of the nitrogenous and non-
nitrogenous compounds. Some of the changes are phys-
ical rather than chemical in character. All of the differ-
ent nutrients of foods are influenced by the action of heat.

Fig. loi. — Comparative composition of raw and baked beans.

Starch, in the presence of water and heat,, undergoes
partial hydration, so that the material is in a condition

384 AGRICULTURAI, CHEMISTRY

both chemically and mechanically to undergo readily in-
version changes. In the cooking and preparation of foods,
starch rarely undergoes more than the hydration
change. In bread-making, for example, only a small
portion of the original starch is converted into soluble
forms.

The action of heat upon cellulose and cellular tissue
is mechanical rather than chemical. The mass is partially
disintegrated and in the case of some of the cellulose,
hydration takes place to a limited extent. Human foods,
however, contain comparatively little of the cellulose
group of compounds. The sugars are partially caromel-
ized by heat, provided it is sufficiently intense, but in
ordinary cooking operations, they undergo little or no
chemical change unless associated with acids, alkalies
or ferment bodies, in which case they may be converted
into a number of chemical products.

In the cooking of fruits, as the baking of apples, a por-
tion of the levulose of the fruit-sugar is partially carbon-
ized. In case the fruit is not fully matured, the pectose
substances or jellies are converted into a more soluble
condition by the action of heat. When heat is sufficiently
intense, the essential or volatile oils are expelled.

Fats, as a class, undergo slight oxidation changes by
the action of heat. In the process of bread-making, for
example, the fat extracted from the bread is different in
character from that in the original flour. It is darker in
color, and chemical tests show that it is slightly oxidized.
Heat causes the proteids to undergo more complex
changes than any other class of nutrients. The soluble

RATIONAL FEEDING OF MEN 385

albumins are coagulated, the globulins also are coagulated,
and if the heat is sufficiently intense, molecular changes
take place, in which the elements composing the proteid
molecule are rearranged in a different way forming, prac-
tically, a new molecule with different chemical and phys-
ical properties. Since the proteid compounds contain
fatty acid radicals, carbohydrate-like bodies, amides and
radicals of other compounds, a number of chemical
changes may take place, varying with the degree of heat
employed.

The chemical changes which take place in the process
of cooking influence, to a limited extent, the digestibility
of the foods. As a rule, the total digestibility of the
carbohydrate nutrients is changed but little by the action
of heat. For example, experiments have shown that the
carbohydrates in toast are no more completely digested
than the carbohydrates in bread, but the action of heat
in the preparation of toast produces chemical and phys-
ical changes which render the nutrients more susceptible
to the action of the digestive fluids, and while toast is no
more completely digested than bread, it is more readily
acted upon by the digestive fluids. Experiments show
that prolonged heat has a tendency to decrease the di-
gestibility of the proteid compounds as a class. In toast,
the proteid nutrients are slightly less digestible than in
bread.

In general, it can be said that cooking effects ease of
digestion rather than completeness of the process, that
the carbohydrates are practically as digestible before the
action of heat as after and that the proteids are slightly

386 AGRICULTURAL CHEMISTRY

less digestible after the action of prolonged heat. Ex-
periments in the feeding of animals have shown that when
foods are cooked, the total digestibility of the nutrients
is not increased, and in some cases, a smaller amount of
nutrients was absorbed after cooking than before. This
does not mean that the cooking of foods is undesirable
because ease of digestion is equally as important as com-
pleteness of digestion. Also cooking sterilizes the food,
which is desirable. Many foods, if consumed uncooked,
would be unwholesome because of the presence of ferment
bodies or poisonous compounds as ptomains. When
acted upon by heat, the ferment bodies are destroyed and
the ptomain compounds decomposed.

When salt, soda and other chemicals are used, chem-
ical changes, to a limited extent, take place. Soda, for
example, combines with the proteid compounds, forming
alkali proteids and the acids form acid proteids. In
cooking and preparing foods, many of the physical
changes which take place precede and are necessary to the
chemical changes. In the boiling of potatoes, for exam-
ple, heat changes the physical character of the cells but
does not alter the solubility of the starch. The albumin
is coagulated and small amounts of the mineral com-
pounds and other bodies are extracted. In the cooking
of some of the cereals, as oatmeal, if the process is con-
tinued for only a few minutes, the starch is not acted
upon to any appreciable extent because of the relatively
large amount of gelatinous proteids which protect the
starch particles. If the cooking is continued for three
or four hours, the material is disintegrated, the starch

RATIONAL FEEDING OF MEN

387

cells are ruptured, and instead of masses of starch, small
particles of disintegrated starch may be observed. This
starch is partially hydrated. Oatmeal cooked in the two
ways, for a few minutes, and for four hours, contains
practically the same percentage amount of total starch.
In the one case, however, the starch is in large masses,
unruptured and unaltered, while in the other, the starch
masses have been ruptured, the particles are in a finer
state of division and are partially hydrated. Oatmeal
which has been cooked for only a few minutes does not
readily undergo digestion, but the four hours' cooking
produces physical and intermediate chemical changes
that cause the starch to
yield readily to the action
of the diastase ferment.
In the cooking of
meats, the heat liquefies
a portion of the fat and
oxidizes a portion of that
which is exposed to the
air, while the proteids
undergo complex molec-
ular changes. In the
cooking and preparation
of foods, it should be the
object to bring about

physical rather than Fig. 102— composition of bread.

chemical changes. Cooking influences the ease rather
than the completeness of digestion.

509. Refuse and Waste Matters.— Nearly all foods

388 AGRICULTURAL CHKMISTRY

contain some refuse material which cannot be consumed
as food. In average meat, as purchased in the market,
from 7 to 56 per cent, is bone and trimmings. Round
steak has least waste while shank has most. Tables
showing the average amounts of refuse in meats are given
at the close of the chapter. The amount of refuse and
waste which a food contains is frequently large enough
to make the nutrients of the edible portion quite expen-
sive even in apparently cheap foods. In vegetables, the
refuse ranges from 15 to 50 per cent. About 15 per
cent, of the weight of potatoes is lost as parings ; of fresh
peas, one-half of the weight is pods, and of squash, one-
half the weight is rind and seeds. In calculating the
nutrients of foods, the refuse and waste parts are to be
considered, as there is nearly always a smaller percentage
amount of nutrients in the food as purchased than in the
edible portion.

510. Loss of Nutrients in the Preparation of Foods. —
In the cooking of vegetables, as potatoes, carrots and
cabbage, some of the soluble nutrients, as albumin, sugar
and mineral matter are extracted and lost in the water.
In the case of potatoes, experiments have shown that
over 57 per cent, of the total nitrogenous matter is ex-
tracted and lost when the potatoes are cut in small pieces
and soaked in cold water. When the cleaned, unpeeled
potatoes were placed directly into hot water, the losses
amounted to only i per cent. In the case of carrots and
cabbage, the losses are large if the pieces are small and
much water is used. The losses from meats incident to
cooking need not necessarily be large provided mechani-

RATIONAL FEEDING OF MEN 389

cal losses are avoided. In the boiling of meat, there is a
decrease in weight of about 30 per cent, due largely to
loss of water. About 5 per cent, of proteid matter is
extracted, also 13 to 15 per cent, of fat and 51 per cent.
of mineral matter. With small pieces of meat, the total
loss of weight may be over 50 per cent. The amount
of nutrients dissolved varies with the size of the
pieces. From experiments made at the University of
Illinois, there does not appear to be any great difference
in the amount of nutrients extracted from meats by hot
or cold water. If the broth is utilized for soup, the nu-
trients extracted during cooking are not lost.

511. Mineral Matter in a Ration. — In the calculation
of human as well as animal rations, the mineral content
of the food is not considered along with the other nutri-
ents. This is not because the mineral nutrients are of
insignificant value but because nearly all combinations of
food contain sufficient, both in amount and variety, for
food purposes. Phosphates, compounds of iron, potas-
sium and magnesium are required only in comparatively
small amounts. It is estimated that with a man at hard
labor from 2 to 3.5 grams per day of phosphoric acid are
eliminated through the kidneys. Since this includes all
of the soluble mineral phosphates of the food, and not all
of those are used for functional purposes, it is not neces-
sary that the food should contain even 2 to 3.5 grams
of available phosphates per day. A ration consisting en-
tirely of white bread contains enough phosphates to sup-
ply the body and establish a phosphate equilibrium. An
average daily ration of mixed foods contains from 5 to 8

390 AGRICULTURAL CHEMISTRY

grams or more. Meats and nearly all animal foods con-
tain about one per cent, of mineral matter of which about
half is phosphoric acid. Milk and eggs contain phos-
phates and mineral matter in liberal amounts. In a
mixed ration of three or more food articles, there is al-
ways enough phosphates and mineral matter for purposes
of nutrition. A part of the excess of phosphates in a
ration is eliminated through the kidneys. The feces also
contain phosphoric acid. Inability of the organs to as-
similate phosphates, due to malnutrition and lack of
available forms of other nutrients, is more frequently a
source of trouble than lack of phosphates in the food.

It is estimated that in the ration of an adult, about 20
grams per day of sodium chlorid are necessary. This
compound takes an important part in nutrition and is a
normal constituent of all the fluids of the body.

512. Digestibility of Foods.— The digestibility of
foods is a subject which belongs for investigation alike
to the chemist, the physiologist, and the bacteriologist.
The physiologist considers the structure of the digestive
tract and the functions of the various organs ; the chem-
ist studies the chemical changes which occur while the
food is undergoing digestion, the completeness of the
digestion process, and the extent to which the nutrients
of the food are made available to the body ; the bacteri-
ologist deals with the ferment bodies which assist in the
process of digestion.

513. Digestibility of fleats.-^The nutrients of meats,
particularly the fats and proteids, are more completely

RATIONAI. FEEDING OF MEN 39I

digested than the same classes of natrients in vege-
tables. From 93 to 95 per cent, or more of the pro-
teids and fats from foods of animal origin are completely
digested, while of vegetables not more than 85 per cent.
of the proteids are completely digested except in the case
of finely ground flour. Meats are concentrated foods as
they furnish large amounts of nutrients in digestible forms.
There is less difference in the completeness with which
the various meats are digested than in the ease of diges-
tion. Some meats, as pork, veal and mutton, which are
called indigestible, are slow of digestion but are quite com-
pletely digested. The nutrients of meats can, for all
practical purposes, be considered entirely digestible.

514. Digestibility of Vegetable Foods Vegetable

foods are less completely digestible than animal foods.
The larger the amount of cellulose or fiber, the less com-
pletely digested is the food. Only a very small amount
of the cellulose, even hydrated cellulose, of human
foods is available to the body. In many vegetables
the nutrients are enclosed in cellular tissue and
thus, to a certain extent, are protected from the solvent
action of the digestive fluids. The starches and carbo-
hydrates of vegetables are more completely digested than
the proteids. Frequently, 95 per cent, of the starch,
while only 80 per cent, or less of the proteids, is digested.
There is quite a wide range in the digestibility of the
nutrients of vegetable foods. The nutrients of fruits are,
as a rule, more completely digested than those from other
vegetable sources, but fruits contain only comparatively
small amounts of nutrients.

392 AGRICULTURAL CHEMISTRY

515. Relation of Food to Health. — Since the function
of food is to supply the body with nourishment, the sub-
jects of food and health are necessarily closely related.
If too long continued, either an abnormal or too scant an
amount of food affects the health. Not only is the
amount important to health but also the quality of the
food as nature of nutrients and sanitary condition. Many
diseases result from malnutrition, while many others are
caused by the use of foods in an unsanitary condition.
Food may cause disease either on account of its unsani-
tary condition or because of an excessive or deficient
amount of nutrients, or because of an unbalanced con-
dition of the nutrients.

RATIONAL FEJEDING OF MEN

393

Composition of Human Foods.

(From Bulletins Nos. 28 and 34, Office of Experiment Stations.)

Kind of food.

Beef — Chuck ribs :

Edible portion

As purchased

Loin :

Edible portion

As purchased

Neck :

Edible portion

• As purchased

Ribs:

Edible portion . .

As purchased

Round :

Edible portion

As purchased

Rump :

Edible portion

As purchased

Shank, fore :

Edible portion

As purchased

Shank, hind :

Edible portion

As purchased

Fore quarter :

Edible portion

As purchased

Hind quarter :

Edible portion

As purchased

Cooked, corn'd & can'd:
As purchased

Dried and smoked :
As purchased

va

13-8

13.0
27.6
20.8

7-7
21.4

36.9
53-9
19.4

I's-s

57-3
49-3

60.5
52.6

63.4
45-9

55-4
43-8

65.8
60.7

56.7

44-5

67.9
42.9

67.8
31-3

61.4
49-5

61.0
51-3

53-1
50.8

01 a Jr,

42.7
36.9

39-5

34-4

36.6
26.5

44.6
35-4

34-2
31.6

43-3
34-1

32.1
20.2

32.2
14.8

38.6
3I-I

39-0
32.9

46.9
49.2

da

Fat.
Per cent.

17.4

24.4

I5-0

21.1

18.3

20.2

15-9

17.6

19.2

16.5

139

II.9

16.9

26.8

13-4

21.3

19.7
18.1

13-5
12.6

16.8

25.6

13.2

20.2

19.6

II. 6

12.3

7-3

19.8

II-5

91

5-3

17-5

20.2

14. 1

16.3

18.0

20.1

15-2

17.0

28.5

14.0

31.8

6.8

fc.il

V a
fa 0

0.9
0.8

i.o
0.9

0.9
0.7

0.9
0.7

I.O

0.9

0.9

0.7

0.9
0.6

0.9

0.4

0.9

0.7

0.9

0.7

4.4

1355

II70

II90
1040

1055

760

1445
1 150

935
870

1395
1095

855
535

855
395

1 180
950

1 185
1000

1 120

84s

394

AGRICULTURAL CHEMISTRY

Composition of Human Foods — {Cofitinued).

Kind of food.

Veal — Leg, whole :

Edible portion

As purchased

Rump :

Edible portion

As purchased

Fore quarter :

Edible portion

As purchased

Hind quarter :

Edible portion

As purchased

Lamb — Leg, hind :

Edible portion

As purchased

Loin :

Edible portion •• .

As purchased

Neck ;

Edible portion

As purchased

Shoulder :

Edible portion

i^ :^ purchased

MuTTON^Leg, hind :

Edible portion

As purchased

Lo'n :

Edible portion

As purchased

Neck :

Edible portion . . ^

As purchased -..>-....

Shoulder :

Edible portion = .

As purchased

15-6

30.2

24-5

20.7

17.4

14.8

17.7

20.3

15-3

28.4
21.7

"J 2 I.

70.4

59-4

62.6

43-7

71.7
54-2

70.9
56.2

63-9
52.9

53-1
45-3

56. 'y

46.7

51.8
41-3

62.8

51-4

50.1
42.2

58.2
41.6

61.9

485

29.6
25.0

37-4
26.1

28.3
21.3

29.1
23.1

36.1
29.7

46.9
39-9

43-2
35.6

38.4

37-2
50 5

49-9
42.5

41.8
30.0

38.1
29.8

5 c

20.1

6.9

20.1

4.0

9-4
4.6

9.8
5.7

8.5

5-2

7.6

7-5

4.4

7-5
4.0

8,2
4-9

5-9
3-2

6.3

1-7

7-3
3-5

. n

en u
ft. u

8.4
7.2

16.2

II-3

8.0
6.0

8.3
6.6

16.5
13-6

28.3
24.1

24.8
20.4

29.7
23.6

18,0
14.9

33-2
28.6

24-5
17.6

19.9
15-6

< ^

I.I
0.9

I.I

0.8

0.9

0.7

I.O
0.8

I.I
0.9

0.8

i-o L375
0.8

1.0

0.8

1.0

0.8

0.8

0.7

1.0

0.7 I 960

0.9 j 1160
0.7 I 910

RATIONAL FEEDING OF MEN

395

Composition of Human Foods — {Continued) .

Kind of food.

Mutton — (Contin'd).

Fore quarter :

Edible portion

As purchased

Hind quarter :

Edible portion

As purchased

Side, without tallow :

Edible portion

As purchased

Pork — Flank :

Edible portion

As purchased

Ham, smoked :

Edible portion

As purchased

Shoulder, fresh :

Edible portion

As purchased

Salt, clear fat :
As purchased

Salt, lean ends :

Edible portion

As purchased

Bacon, smoked :

Edible portion

As purchased

Side:

Edible portion

As purchased

Poultry — Chicken :

Edible portion

As purchased

Turkey :

Edible portion

As purchased

16.7
19.2
71.2
14.4
46.6

8.0

34.8

t

,22.7

51-7

40.6

54-8
45-6

53-1
42.9

59-0
17.0

40.7
34-9

57-5
30-4

7-3

19.9
17.6

18.2
16.8

29.4
26.1

74.2
48.5

55-5
42.4

u * o

48.3
38-3

45-2

37-7

46.9
37-9

41.0
II. 8

59-3
50.7

42.5
23.0

92.7

80.1
71.2

81.8
75-2

70.6
62.7

25.8
16.7

44.5
34-9

15.0

II. 9

16.2
13-5

15-4
12.5

17.8
5-1

15-5
13-3

15-6
8.3

7-3
6.5

lo.o
9.2

8.5
7-5

22.8
14.8

20.6
15-7

(I, u

32.4

25-7

28.2
23-5

30-7
24.7

22.2
6.4

39-1
33-4

26.1

14-3

87.2

67.1
59-6

67.2
61.8

61.7
54.8

1.8
i.i

22.9
18.4

^ V

P4

0.9
0.7

0.8
0.7

0.7
0.7

I.O
0.3

4-7
4.0

0.8
0.4

3-7

5-7
5-1

4.6

4.2

0.4
0.4

1.2
0.8

1.0
0.8

1645
1305

1490
1245

1580
1275

1265
365

1940
1655

1390
760

3715

2965
2635

3020
2780

2760
2455

500
325

1350
1070

396

AGRICULTURAL CHEMISTRY

Composition of Human Foods — {Continued).

Kind of food.

56.3

Fish , fresh — Cod .dried

Edible portion

As purchased : 29.9

Mackerel, entrails rem'd: I

Edible portion ]

As purchased 140.7

Salmon, Cal., sections:

Edible portion * * " "

As purchased 10.3

Salmon trout, whole:

Edible portion

As purchased

Trout, brook, whole:

Edible portion

As purchased 48. i

Fish, pres'd, cod, salt:

Edible portion

As purchased

Mackerel, salt:

Edible portion

As purchased

Salmon, canned, as purc'd
Sardines, can'd, as purc'd

Shellfish, clams, round:

Edible portion !

As purchased 67.5

Oysters, "solids," as pur' d

Dairy Products :

Cheese — Cheddar

Butter

*Milk

*Cream

Eggs :

In shell

Edible portion

24.9

22.9

13-7

^g-

82.6
58.5

73-4
43-7

63.6
57-9

69.1
30.0

77.8
40.4

53-6
40-3

42.2
32-5
64-5
56.4

86.2
28.0
88.3

33- 00
13.00
87.00

63.1

73-8

17.4
11.6

26.6
15-6

36.4
31-8

30.9
13-7

22.2

46.4
34-8

.57-8
44.6

35-5
43-6

13-8

4-5

11.7

67.00
87.00
13.00

23.2
26.2

15-8
10.6

18.2
11.4

175
16. 1

18.2
7-7

18.9
9.8

21.4
16.0

22.0
17.0
20.1
25-3

6.5
2.1
6.1

28.00
0.50
3-5
2.5

12. 1
14.9

0.4
0.2

7-1
3-5

17.9
14.8

11.4
5-4

2.1
I.I

0.4
0.4

0.4
0.1
1.4

1.2
0.8

1-3

0.7

I.O

0.9

1-3
0.6

T.2
0.6
I

24.6
18.4

22.6 '13.2

17.4 ilO.2

11. 6 ! 2.4

12.7 I 5.6

2.7
0.9
0.9

35. OO; 4.0

85.00! 1.5

4.OOJ 0.7

20.0 0.5

10.2
10.5

0.9
0.8

* Milk also contains 4.8 per cent, carbohydrates,
ranges from 10 to 30 per cent.

The fat content of cream

RATIONAL FEEDIKG OF MJ5N

397

Composition oi^ Human Foods — {Continued^.

Kind of food.

Wheat flours, meals, etc.

*Roller process flour

Spring wheat flour

Winter wheat flour

Buckwheat flour

Cornmeal, bolted

Oatmeal

Rice

Rice, boiled

* White bread

*Graham bread

Crackers

Sugar, granulated

Sugar, maple

Vegetables — Asparagus
As purchased

Beans, dried.
As purchased

Beets :

Edible portion

As purchased

Cabbage :

Edible portion

As purchased ■

Carrots :

Edible portion

As purchased .

Parsnips :

Edible portion

As purchased . — - • . . . •

Peas, dried :
As purchased

Peas, green :

Edible portion

As purchased

ir.9
II. 6

12.5
14-3
12.9

7-2
12.4

52-7

31.0

32.2

8.2

■5-q

50.0

94.0

13.2

87.6
70.0

90-3
76.8

88.2
70-5

79-9
63-9

10.8

78.1
39-0

s ^

And,

12.6

II.8

10.4
6.1
8.9

15-6
7.8
5-0
9-9
9-5

10.7

1.8

22.3

1.6
1-3

2.1
1.8

I.I
0.9

1-7
1-3

24.1

4.4
2.2

0.8
I.I
i.o
i.o
2.2

7-3
0.4
o.i
1.4
2.5
9-9

0.2

1.8

0.1
0.1

0.4
0-3

0.4
0-3

0.6
0.5

0.5
0.3

74-3
75-0
75-6
77.2

75-1
68.0
79.0
41.9
57-1
54-7
68.8
98.0
82.8

3-3

59-1

9.6

7-7

58

4.9

9.2
7-4

16.1
12.9

61.5

16.1
8.0

0.4
0.5
0-5
1.4
0.9

1-9

0.4

0.3
0.6
I.I

2.4

'* 9

1650
1660
1640
1590
1655
i860
1630

875
1306

1895
1600

1540

0.7 I 105
3-6 j 1590

I.I

0.9

1.4
1.2

I.I
0.9

1-7
1.4

2-5

0.9
0.5

210
170

165

140

210
170

355
285

1640

400
200

* From Minnesota analyses.

398

AGRICULTURAI, CHEMISTRY

Composition of Human Foods — {Co7itinued).

Kind of food.

Potatoes, raw :
Edible portion . • .
As purchased . • . .

Potatoes, sweet
Edible portion . . .
As purchased • • . •

Squash :
Edible portion . . .
As purchased • . . •

Turnips :
Edible portion . . .
As purchased . • .

Tomatoes :
Edible portion . . •

Green corn

Cucumber

Spinach

Sauer kraut

I5-0

50.0

30.0

at

.0

<^ V

2 ^

^ u

Ph

t^fu

Oc

78.9

2.1

O.I

67.1

1.8

O.I

6q.3

1.8

0.7

58.9

1-5

0.6

86.5

1.6

0.6

433

0.8

0.3

88. q

1.4

0.2

62.2

I.O

O.I

96.0

0.8

0.4

81. s

2.8

I.I

96.0

0.8

0.2

92.4

2.1

0.5

86.3

1-5

0.8

O <u

18.0

15-3

27.1
23.1

10.4
5-2

8.7

6.1

2.5
14. 1

2.5
3-1
4.4

0.9
0.7

I.I
0.9

0.9
0.4

0.8
0.6

0-3
0.7

0.5
1-9
7.0

<u a
3 3
fe 0

380
325

565
480

245
125

195
135

80
360

70
120
145

INDEX

Acid, citric • » 207

hydrochloric 80-82

malic 206

oxalic 206

phosphoric 94

salts 75

sulfuric 99

tannic 207

tartaric 206

Acids 37, 72

basicity of 76

fatty 199, 2or

naming of 74

organic 205

Aerobic ferments 319

Air ,. 66-71

a mechanical mixture 66

ammonium compounds of • . .68

as plant food 71

carbon dioxid of 66, 68

impurities in 70

moisture in 69

Albumin in meat 370

Albumins 218

Albuminates 220

Albuminoids 226-228

food value of 227

Alfalfa • 267

Aliphatic series 114

Alkaloids 231

Allotropism 48

Aluminum 145

in plants 168

Alums 146

Amides 228-231

food value 230

occurrence in animals ..229

plants .. .229

Ammonia 88

Ammonia, properties of ... 89

uses of 90

Ammonium compounds in air. ..68

Anaerobic ferments 319

Anhydrids 91

Animal bodies, composition of-

366-369

fat in 367

mineral matter

in 366

nitrogenous mat-
ter of 368

Animal life, chemical change 2

Apatite 93

Apparatus, names of 19-21

Apples 134

Argon 70

Aromatic series 114

Arsenic, occurrence 152

poisoning 153

Ash determination 160

Ash elements, essential 162

of animal bodies 366

of plants 159-174

composition of 173

Atomic weight 13

table of II

Atoms 4

Bacteria, disease-producing 323

Balanced rations 344

calculation of -355

Barley 297, 302

grading of 301

Bases 72

naming of 74

Beans 299

Beef production, foods for .348-351
Benzine 113

400

INDEX

Bessemer process 142

Blast-furnace 141

Bleaching-powder 136

Bordeaux mixture 149

Brick 147

Bromus Inermis 265

Buckwheat 298

Burette 77

Calcium 134

carbonate 134

chlorid 136

compounds 134-139

hydroxid 135

hypochlorite 136

in plants 168

oxid 135

phosphate 136

sulfate 1 36

Caloric value of rations 358

Calorie 184, 327

Calorimeter 327-331

Candle, chemistry of 52-54

power 112

Capillarity of plant tissue 241

Carbids 115

Carbohydrates 176-196

digestibility of ••333

Carbon 46-55

a reducing agent 48

compounds 54

a decolorizer 52

deodorizer 52

dioxid 107

in air 66-68

test for 135

disulfid 114

monoxid 108

occurrence 46

oxids of 107

preparation of 46

properties of 47

role in plant and animal

life 54-55

Carbonates 107

Carrots 313

Cellulose 177-181

chemical properties of 1 78

food value of 179

function of 178

physical properties of . 177

Chemical affinity 5

analysis 6

changes 2

properties defined ..9-10

Chemistry 2

Chlorids.' 85

Chlorin 82

family 84

preparation 83

properties 84

Chlorophyl 242-246

function of 245

production 243

Clay 105

Cleaning apparatus 28-29

Climate and plant growth 260

Clover, composition of * 250

early and late cut 249

hay 266, 271

rapidity of growth 248

Coal 48

Combination of elements- 12, 16, 17

Combustion 49

products of 53

spontaneous 51

Composition of matter 1-7

Compounds 5

Cooking of foods, changes during

carbohydrates 384

fats 385

proteids 385

losses during 388

Copper 148

compounds 148-149

sulfate 1 48

Corks, perforation of 22

Corn (see maize).

flour 294

fodder 268

INDEX

401

Cottonseed cake and meal 308

Creosote 113

Crop growth and soils 258

Crops, improvement of 262

Crude fiber 179

protein 224

Crystallization, water of 58

Dairy cows, food for 352

requirements of. 35 1

Definite proportion, law of 15

Dextrin 186

Dextrose 190

chemical and physical

properties of 191

Dialysis 104

Dietary standards 374

studies 382

Digestible nutrients 341

in fodders and
grains... 363-365
Digestion, a bio-chemical pro-
cess 325

chemistry of . . .325-344

coefficients 339

not con-
stant... 339

experiments 325

factors influencing. 334
Digestibility, factors influencing

379-381

influence of cook-
ing vpon....338, 385

Disease, air 70

and water supply. ..59-60

Double salts 75

Dry matter 157

Elastin 227

Elements and compounds, prop-
erties 8-18

classification of 72

combination of. 12, 16, 17
cycle of 119

Energy, available, of food? ... .331

Energy, net, of foods 332

Epsom salt 138

Equations 120-126

for classroom . . .124-126

Essential oils 208-21 1

food value 210

synthetic produc-
tion of 210

Ether extract 203-204

Fat in animal bodies 367

Fats 197-205

amounts of, in foods 203

chemical properties 198

digestion of 334

food value of 201

formation in plants 197

heat from 201

physical properties 198

Feeding of animals 344-356

and sanitary conditions 361

standards 362

stuffs, inspection of .. .310

Feldspar 105

Fermentation 318-324

conditions neces-
sary for 320

Ferments, aerobic 319

anaerobic 319

and bread-making . .321
in butter- and cheese-
making 321

disease-producing. . -323

and food digestion. .322

preservation 322

in seeds 320

soils 320

insoluble 318

soluble .318

Fertilizers, phosphate 94

Fiber, crude 1 79

Filter-paper, folding of 26

Flame, structure of 52

Flax, rapidity of growth 251

Flaxseed, grading of 301

402

INDEX

Fodders, composition of . . .263-272

cutting of 260

Foods, caloric value of 327

combination and digesti-
bility of 336

cost and value of 359

factors influencing di-
gestibility 379-381

influence of cooking

upon digestibility . . . .338
mechanical condition of,

and digestion 335

palatability of 337

refuse and waste matters

of 387

Food, relation of, to health . . • • 392
requirements of animals. 345
supply and stage of

growth 346

Formula 12

Formulas, structural 186

Fruits 314-316

dried 316

food value 317

Fuels 115

Galvanized iron 150

Gasoline, use of no

Gelatin 227, 372

Germination of seeds 237-239

conditions nec-
essary for . . . 239

Glass 1 38

tubing, bending 22

cutting 21

Gliadin 275

Globulins 219

Glucose, test for 149

Gluten 277

meal 309

Glutenin 275

Grains, composition of 302

cost and value of 359

grading of 299

Grapes 315

Grass, pasture 268

Gypsum 136

Helium 70

Hemoglobin 371

Horses, foods for 348

food requirements of • -347
Human and animal feeding com-
pared 374

body, composition of ••373

food problems 379

foods, composition of. .

393-398

cost and value of 377

rations 376

calculation of. . .376
requisites of .... 38 r

Hydrated cellulose 178

Hydrocarbons 109

Hydrochloric acid 80-82

preparation • .80
properties. . . .82

Hydrogen 37-41

importance 41

occurrence 37

preparation 37-38

properties 39

peroxid 70

sulfid 102

Hydroxyl 72, 74

Illuminating gas in

Indestructibility of matter 3

Insecticides 152

Insoluble proteids 222

Invert sugars 189

Iron 140

compounds 140-144

Iron, galvanized 150

in plants 168

ores, reduction 140

rusting of 144

wrought 142

Keratin 371

INDEX

403

Kerosene oil , testing of no

Laboratory manipulation .... 19-30
practice, important • 19

Lactose 1 89

Law of definite proportion 15

multiple proportion 91

Lead 150

carbonates 151

compounds 150, 151

oxids 150

uses of 151

Lecithin 234

Lemons 314

Levulose 192

Ligno-cellulose 178

Lime kiln 134

Lime, slaking of 137

Limestone 134

Linseed meal 307

Magnesium, occurrence 138

in plants 167

salts 138

Maintenance ration 344

Maize as food 294

as forage 252

composition of 252-256

kernel- • .289

grading of 293

liusk 255

leaves 254

nitrogenous and non-
nitrogenous 291

products 294

proteids of 290

roots 252

stalk 253

structure of kernel 289

varieties of 293

Malt sprouts 309

Maltose 189

Mangels 313

Marsh gas 109

Matter, indestructibility of 3

Measuring liquids 24

Meats, albumin of 370

albuminoids of 372

composition of 393-396

digestibility of 390

proteins of 370

Mechanical mixtures 6

Mercury 153

compounds 153

Metric equivalents 23

Mica 105

Milk solids 158

sugar 189

Mill and by-products 303-311

Millet 299

Mineral food, assimilation of, by

plants 247

matter of crops . . . 159-174

oils 112

in a ration 389

Minium 151

Molecules 3

Molecular weights 11-14

Mortar 137

Mucin 227

Multiple proportion, law of 91

Myosin 370

Naming of acids 74

bases 74

salts 75> 76

Neutralization 72, 76

Nitrates 86

Nitric acid 86-88

importance 88

preparation 86

properties 88

Nitrogen 42-46

assimil a t i o n of, by

plants 247

compounds, impor-
tance of 45, 92

determination of 225

Nitrogen-free extract 196

Nitrogen, occurrence 42

404

INDEX

Nitrogen, oxids of 90

preparation 42-43

properties 44

role in plant and ani-
mal life 45

Nitrogenous compounds- . .214-235
matter, animal bod-
ies 368

Non-nitrogenous compo u n d s,

food value 213

Non-nitrogenous compo u n d s,

general relationship 212

Note-book, laboratory 27

Nuclein 226

Nutrients, digestible, of foods.. 341

Nutrition 325-366

Nutritive ratio 357

Oat feed 308

hay 265

Oats, composition of 296

as food 297

grading of 300

structure of kernel 296

Olein 200

Olives 316

Oranges 314

Organic compounds in plants . . 117

matter 175

decay of 118

production of • • 245

Osmosis 241

Oxidation 35

Oxids 34

Oxygen 31-37

importance 35

occurrence 31

preparation 31

properties 34

Ozone 70

Palmitin 199

Paris green 153

Parsnips 313

Pectin bodies 196

Pentosans 195

Peptic ferments 322, 333

Peptones 221

Petroleum 109

Phosphates 94

fertilizers 94

in human foods . • .389

Phosphoric acid 94

Phosphorus 93

compounds 95

importance 95

oxids 93

in plants 169

properties 93

Physical change 2

properties defined • . .8-18

Physics 2

Pigs (see swine).

Plant ash 155-174

growth 235-246

juices, movement of 240

life, chemical change 2

physical change 2

Plaster of Paris 136

Plumbing 29

Polariscope 194

Porcelain 147

Potassium 127

carbonate 129

chlorate 129

compounds ....127-130

hydroxid 127

nitrate 128

in plants 164

sulfate 1 29

Potatoes 312

Pottery 147

Prairie hay 265

Properties, chemical 9-10

of elements and com-
pounds 8-18

physical 8-9

Proportion, law of definite 16

Protein, crude 224

Proteids 215

INDEX

405

Proteids, amount in plants . . . • 224
chemical properties ..217

classification 218

digestibility of ^,3^,

food value 223

insoluble 222

of meat 370

physical properties. . .216

of wheat 274

Proteoses 221

Protoplasm 243

Quartz 103

Radicals 73

naming of 74

Rape 267

Rational feeding of animals . 344-366

men. -..374-398

Rations, balanced 344

caloric value of 358

maintenance 344

standard 345

Reactions 120-126

illustrated 121, 122

impossible 123

Reagent bottles, handling of . ... 25

Reduction 48

Rice 298

Roots 312, 313

Rye 298, 302

grading of 300

Salts 75

acid 75

double 75

naming of 75, 76

Sand culture 164

Sanitary conditions and feed-
ing .•••• •. 361

Saponification 200

Seeds 235-239

ash of 235

and crop growth 257

nitrogenous compounds of 236

Sheep, food requirements of . . .354

Silage 269

SiHca 103

Silicates 105

Silicic acid 103

Silicon 103

compounds, importance

of 105

Silo, losses in 270

Sodium 1 29

carbonate 131

chlorid 130

hydroxid 132

nitrate 131

phosphate 132

in plants 1 68

salts 130-133

Soils 105

Spontaneous combustion 51

Starch 181-186

chemical properties i8r

food value 184

function 1 83

physical properties 182

in seeds 237

Stearin 199

Steel 142

Steer-feeding 348-351

Stover 268

Straw 263

Strawberries 315

Sucrose 1 88

chemical properties • • . 188
physical properties. ... 188

Sugar ..., 1S7-195

beets 194

Sulfates loi

Sulfids loi

Sulfur 97

dioxid 98

preparation 97

properties 97

uses 98

in plants 170

Sulfuric acid 99

4o6

INDEX

Sulfuric acid properties loo

Swine, food requirements of . . .353

Symbols 10

Syntonin 370

Timothy hay 264, 274

Tin 150

salts 150

Tubing, glass, bending 22

cutting 21

Turpentine 113

Typhoid bacillus 59

Trypsin 333

Valence 15

table of II

Vegetable foods 397-398

digestibility of 391
Ventilation of rooms 67-69

Water 56-65

borne diseases 59

contamination of 61, 62

culture 163

of crystallization 58

distillation of 57

electrolysis 56

filters 63, 64

mineral matter of 61

natural 59

organic matter in 60

oven. 155

physical properties 57

in plants 155, 157

purification of 64, 65

Waxes 201

Weighing 23, 160

Weights, atomic i, 13

molecular 14

Wheat 273-288

American and foreign . 288

as animal food 286

as human food 287

bran 304

bread-making properties

of 277

by-products 303

composition of varieties. 285

flour, grades of 303

germ 306

gluten of 277

grading of 283

influence of climate npon28i
f e r t i 1 izers

upon 279

middlings 305

nitrogen content of, and

flour 278

proteids of 274

rapidity of growth 247

screenings 307

shorts 306

storage of 282

structure of kernel 273

unsound 284

variations in composition279
White lead 151

Zeolites 105

Zinc compounds 149

occurrence 149

CORRECTIONS

Page 23, in last line, read " SO^," not " SOj."
Page 94, line 21, read " H^PjO;,'' not " HjPjOy.'
Page 125, Equation 40, read " 3KOH."
Page 132, line 18, read " Na^HPO^."

OUTLINES OF INDUSTRIAL CHEMISTRY

A TEXT-^OOK FOR STUDENTS
By FRANK HALL THORP, Ph.D.

Massachusetts Institute of Technology
New Edition, Fully Revised. Cloth. 8vo. $3.50

"I have examined it carefully and think it a most excellent
book, meeting a want I have long felt in my higher classes. I
have introduced it in this year's classes."

— Professor Charles E. Coaxes, Louisiana State University.

" I feel no hesitation in saying that it is the best book for the
purpose intended that it has been my good fortune to examine.
It fills a very great need for a compact text-book in Technological
Chemistry, and I am sure its use will be extensive. It reaches
the standard of Dr. Thorp's usual excellent work in chemistry."

— Professor Charles Baskerville, Univ, of North Carolina.

" Teachers may congratulate themselves upon the appearance
of this book, for it contains, expressed in a concise manner, much
that would otherwise (with perhaps less happy results) require the
consultation of many books.

" In a work so thorough it is difficult to select any one subject
more carefully treated than the others ; therefore, chemists can
well feel grateful to Professor Thorp for his contribution, and
doubtless few libraries will be without a copy thereof."

— Journal of American Chemical Society.

THE MACMILLAN COMPANY

66 FIFTH AVENUE, NEW YORK

By HARRT C. JONES, Ph.D.

Associate Professor of Physical Chemistry, Johns Hopkins University, authoi
of " Elements of Physical Chemistry" and " Electrolytic Dissociation."

Principles of Inorganic Chemistry

Illustrated Cloth 8vo $4.00 net (postage 23c.)

" The student whose training in general chemistry has lacked illumination by modern
views, whether on account of the ignorance, conservatism, or deliberate preference of his
first instructor, will find in this book abundant opportunity for bringing his conceptions up to
date and getting in touch with the science as it is. To such a student the book will be most
suggestive and stimulating. Dr. Jones is to be congratulated on having produced one of the
best of the recent attempts to apply physicochemical conceptions to undergraduate instruc-
tion."— Alexander Smith in Jourtial of Ajiierican Chemical Society, Easton, Pa.

" The book must be considered the most notable contribution to didactic chemistry pro-
duced by an American since the appearance of the Remsen series of text-books."

— James Lewis Howe in Science.

The Elements of Physical Chemistry

Cloth 8vo $4.00 net (postage 23c.)

Julius Stieglitz lurites: —

" The brief, but carefully prepared, historical sketches introducing many of the chapters,
as, for instance, the one on ' Chemical Dynamics and Equilibrium,' and the great number
of references to original papers form excellent features of the book. The marked enthusiasm
with which the author writes as a worker in the field is bound to interest the student in the
subject as a living one, with many vital problems yet to be solved." — The Journal of
American Chemical Society.

W. R. in Nature describes it as: —

" A fairly comprehensive and reasonably exact sketch of the modern aspects of physical
chemistry in a comparatively small number of pages. The book gives a better bird's-eye
view of the whole subject than most recent works, and it has the great advantage that copious
references make it possible for the student to consult the literature of the subject."

The Theory of Electrolytic Dissociation
and Some of Its Applications

Cloth 8vo xii + 289pp. %\.(iQ net

" Aims only to treat of a single, though the most important, theory of physical chemistry
of to-day — brief, clear, and readable." — Science.

THE MACMILLAN COMPANY

66 Fifth Avenue, New York

•^University of British Columbia Library

•x DUE DATE

FORM 310

AbKICULIUKb

FORESTRY
■ LIBRARY^

L... 1

<■■'.■

TURE

iiiiiiiiiltiiiii itiiiiiiiiitlillitil iiilMliilHiililf iiiltilll

illlllllllllliHIIIIIi