Copyright
Rufus Phillips Williams.

An Introduction to Chemical Science online

. (page 1 of 5)
Online LibraryRufus Phillips WilliamsAn Introduction to Chemical Science → online text (page 1 of 5)
Font size
QR-code for this ebook


An Introduction to Chemical Science

by R.P. Williams, A.M.,


CONTENTS


PREFACE, BY R.P. WILLIAMS
TABLE OF CONTENTS
AN INTRODUCTION TO CHEMICAL SCIENCE
APPENDIX
TEXTBOOK ADVERTISEMENTS THAT APPEARED IN THE ORIGINAL EDITION
INFO ABOUT THIS E-TEXT EDITION


PREFACE, BY R.P. WILLIAMS


The object held constantly in view in writing this book has been to
prepare a suitable text-book in Chemistry for the average High
School, - one that shall be simple, practical, experimental, and
inductive, rather than a cyclopaedia of chemical information.

For the accomplishment of this purpose the author has endeavored
to omit superfluous matter, and give only the most useful and
interesting experiments, facts and theories.

In calling attention, by questions, and otherwise, to the more
important phenomena to be observed and facts to be learned, the
best features of the inductive system have been utilized.
Especially is the writing of equations, which constitute the
multum in parvo of chemical knowledge, insisted upon. As soon as
the pupil has become imbued with the spirit and meaning of
chemical equations, he need have little fear of failing to
understand the rest. To this end Chapters IX., XI., and XVI.
should be studied with great care.

In the early stages of the work the equations may with advantage
be memorized, but this can soon be discontinued. Whenever symbols
are employed, pupils should be required to give the corresponding
chemical names, or, better, both names and symbols.

The classification of chemical substances into acids, bases and
salts, and the distinctions and analogies between each of these
classes, have been brought into especial prominence. The general
relationship between the three classes, and the general
principles prevailing in the preparation of each, must be fully
understood before aught but the merest smattering of chemical
science can be known.

Chapters XV.-XXI. should be mastered as a key to the subsequent
parts of the book.

The mathematical and theoretical parts of Chemistry it has been
thought best to intersperse throughout the book, placing each
where it seemed to be especially needed; in this way, it is hoped
that the tedium which pupils find in studying consecutively many
chapters of theories will be avoided, and that the arrangement
will give an occasional change from the discussion of facts and
experiments to that of principles. In these chapters additional
questions should be given, and the pupil should be particularly
encouraged to make new problems of his own, and to solve theta.

It is needless to say that this treatise is primarily designed to
be used in connection with a laboratory. Like all other text-
books on the subject, it can be studied without such an
accessory; but the author attaches very little value to the study
of Chemistry without experimental work. The required apparatus
and chemicals involve but little expense, and the directions for
experimentation are the result of several years' experience with
classes as large as are to be found in the laboratory of any
school or college in the country.

During the present year the author personally supervises the work
of more than 180 different pupils in chemistry. This enables him
not only to assure himself that the experiments of the book are
practical, but that the directions for performing them are ample.
It is found advisable to perform most of the experiments, with
full explanation, in presence of the class, before requiring the
pupils either to do the work or to recite the lesson. In the
laboratory each pupil has a locker under his table, furnished
with apparatus, as specified in the Appendix. Each has also the
author's "Laboratory Manual," which contains on every left-hand
page full directions for an experiment, with observations to be
made, etc. The right-hand page is blank, and on that the pupil
makes a record of his work. These notes are examined at the time,
or subsequently, by the teacher, and the pupil is not allowed to
take the book from the laboratory; nor can he use any other book
on Chemistry while experimenting. By this means he learns to make
his own observations and inferences.

For the benefit of the science and the added interest in the
study, it is earnestly recommended that teachers encourage pupils
to fit up laboratories of their own at home. This need not at
first entail a large outlay. A small attic room with running
water, a very few chemicals, and a little apparatus, are enough
to begin with; these can be added to from time to time, as new
material is wanted. In this way the student will find his love
for science growing apace.

While endeavoring, by securing an able corps of critics, and in
all other ways possible, to reduce errors to a minimum, the
author disclaims any pretensions to a work entirely free from
mistakes, holding himself alone responsible for any shortcomings,
and trusting to the leniency of teachers and critics.

The manuscript has been read by Prof. Henry Carmichael, Ph.D., of
Boston, and to his broad and accurate scholarship, as well as to
his deep personal interest in the work, the author is indebted
for much valuable and original matter. The following persons have
generously read the proof, as a whole or in part, and made
suggestions regarding it, and to them the author would return his
thanks, as well as acknowledge his obligation: Prof. E. J.
Bartlett, Dartmouth College, N.H.; Prof. F. C. Robinson, Bowdoin
College, Me.; Prof. H. S. Carhart, Michigan University; Prof. B.
D. Halsted, Iowa Agricultural College; Prof. W. T. Sedgwick,
Institute of Technology, Boston; Pres. M. E. Wadsworth, Michigan
Mining School; Prof. George Huntington, Carleton College, Minn.;
Prof. Joseph Torrey, Iowa College; Mr. C. J. Lincoln, East Boston
High.School; Mr. W. H. Sylvester, English High School, Boston;
Mr. F. W. Gilley, Chelsea, Mass., High School; the late D. S.
Lewis, Chemist of the Boston Gas Works, and others.

R. P. W.

BOSTON, January 3, 1888.


TABLE OF CONTENTS


CHAPTER I.

THE METRIC SYSTEM.

Length. - Volume. - Weight

CHAPTER II.

DIVISIBILITY OF MATTER.

Mass.-Molecule. - Atom. - Element. - Compound. - Mixture. -
Analysis. - Synthesis. - Metathesis. - Chemism

CHAPTER III.

MOLECULES AND ATOMS.

Synthesis

CHAPTER IV.

ELEMENTS AND BINARIES.

Symbols. - Names. - Coefficients. - Exponents. - Table of elements

CHAPTER V.

MANIPULATION.

To prepare and cut glass, etc.

CHAPTER VI.

OXYGEN.

Preparation. - Properties. - Combustion of carbon; sulphur;
phosphorus; iron.

Chapter VII

NITROGEN

Separation - Properties

CHAPTER VIII

HYDROGEN

Preparation - Properties - Combustion - Oxy-hydrogen blowpipe

CHAPTER IX

UNION BY WEIGHT

Meaning of equations - Problems

CHAPTER X

CARBON

Preparation - Allotropic forms: diamond, graphite, amorphous
carbon, coke, mineral coal. - Carbon a reducing agent, a
decolorizer, disinfectant, absorber of gases

CHAPTER XI

VALENCE

Poles of attraction - Radicals

CHAPTER XII

ELECTRO-CHEMICAL RELATION OF ELEMENTS

Deposition of silver; copper; lead - Table of metals and non-
metals, and discussion of their differences

CHAPTER XIII.

ELECTROLYSIS.

Decomposition of water and of salts - Conclusions CHAPTER XIV.

UNION BY VOLUME.

Avogadro's law and its applications.

CHAPTER XV.

ACIDS AND BASES.

Characteristics of acids and bases. - Anhydrides. - Naming of
acids. - Alkalies

CHAPTER XVI.

SALTS.

Preparation from acids and bases. - Naming of salts. - Occurrence

CHAPTER XVII

CHLORHYDRIC ACID.

Preparation and tests. - Bromhydric, iodhiydric, and fluorhydric
acids. - Etching glass

CHAPTER XVIII.

NITRIC ACID.

Preparation, properties, tests, and uses. - Aqua regia:
preparation and action

CHAPTER XIX.

SULPHURIC ACID.

Preparation, tests, manufacture, and importance.-Fuming sulphuric
acid

CHAPTER XX.

AMMONIUM HYDRATE.

Preparation of bases. - Formation, preparation, tests, and uses of
ammonia.

Chapter XXI.

SODIUM HYDRATE.

Preparation and properties. - Potassium hydrate and calcium
hydrate

CHAPTER XXII

OXIDES OF NITROGEN.

Nitrogen monoxide, dioxide, trioxide, tetroaide, pentoxide.

CHAPTER XXIII.

LAWS OF DEFINITE AND OF MULTIPLE PROPORTION, and their
application

CHAPTER XXIV.

CARBON PROTOXIDE and water gas.

CHAPTER XXV.

CARBON DIOXIDE.

Preparation and tests. - Oxidation in the human system. - Oxidation
in water. - Deoxidation in plants

CHAPTER XXVI.

OZONE.

Description, preparation, and test

CHAPTER XXVII

CHEMISTRY OF THE ATMOSPHERE.

Constituents of the air. - Air a mixture. - Water, carbon dioxide,
and other ingredients of the atmosphere

CHAPTER XXVIII.

THE CHEMISTRY OF WATER.

Distillation of water. - Three states. - Pure water, sea-water,
river-water, spring-water CHAPTER XXIX.

THE CHEMISTRY OF FLAME.

Candle flame. - Bunsen flame. - Light and heat. - Temperature of
combustion. - Oxidizing and reducing flames. - Combustible and
supporter. - Explosive mixture of gases. - Generalizations

CHAPTER XXX.

CHLORINE.

Preparation. - Chlorine water. - Bleaching properties. -
Disinfecting power. - A supporter of combustion. - Sources and uses

CHAPTER XXXI.

BROMINE.

Preparation. - Tests. - Description. - Uses

CHAPTER XXXII.

IODINE.

Preparation. - Tests. - Iodo-starch paper. - Occurrence. - Uses. -
Fluorine

CHAPTER XXXIII.

THE HALOGENS.

Comparison. - Acids, oxides, and salts

CHAPTER XXXIV.

VAPOR DENSITY AND MOLECULAR WEIGHT.

Gaseous weights and volumes. - Vapor density defined. - Vapor
density of oxygen

CHAPTER XXXV.

ATOMIC WEIGHT.

Definition. - Atomic weight of oxygen. - Molecular symbols. -
Molecular and atomic volumes CHAPTER XXXVI.

DIFFUSION AND CONDENSATION OF GASES.

Diffusion of gases. - Law of diffusion. - Cause. - Liquefaction and
solidification of gases

CHAPTER XXXVIL

SULPHUR.

Separation. - Crystals from fusion. - Allotropy. - Solution. -
Theory of Allotropy. - Occurrence and purification. - Uses. - -
Sulphur dioxide

CHAPTER XXXVIII.

HYDROGEN SULPHIDE.

Preparation. - Tests. - Combustion. - Uses. - An analyzer of metals.-
-Occurrence and properties

CHAPTER XXXIX.

PHOSPHORUS.

Solution and combustion. - Combustion under water. - Occurrence. -
Sources. - Preparation of phosphates and phosphorus. - -
Properties. - Uses. - Matches. - Red phosphorus. - -Phosphene

CHAPTER XL.

ARSENIC.

Separation. - Tests. - Expert analysis. - Properties and
occurrence. - Atomic volume. - Uses of arsenic trioxide

CHAPTER XLI.

SILICON, SILICA, AND SILICATES.

Comparison of silicon and carbon. - Silica. - Silicates. - Formation
of silica.

Chapter XLII

GLASS AND POTTERY.

Glass an artificial silicate. - Manufacture. - Importance. -
Porcelain and pottery.

CHAPTER XLIII.

METALS AND THEIR ALLOYS.

Comparison of metals and non-metals. - Alloys. - Low fusibility. -
Amalgams

CHAPTER XLIV.

SODIUM AND ITS COMPOUNDS.

Order of derivation. - Occurrence and preparation of sodium
chloride; uses. - Sodium sulphate: manufacture and uses. - Sodium
carbonate: occurrence, manufacture, and uses. - Sodium:
preparation and uses. - Sodium hydrate: preparation and use. -
Hydrogen sodium carbonate. - Sodium nitrate

CHAPTER XLV.

POTASSIUM AND AMMONIUM.

Occurrence and preparation of potassium. - Potassium chlorate and
cyanide. - Gunpowder. - Ammonium compounds

CHAPTER XLVI.

CALCIUM COMPOUNDS.

Calcium carbonate. - Lime and its uses. - Hard water. - Formation of
caves. - Calcium sulphate

CHAPTER XLVII.

MAGNESIUM, ALUMINIUM, AND ZINC.

Occurrence and preparation of magnesium. - Compounds of aluminium:
reduction; properties, and uses. - Compounds, uses, and reduction
of zinc CHAPTER XLVIII.

IRON AND ITS COMPOUNDS.

Ores of iron. - Pig-iron. - Steel. - Wrought-iron. - Properties. -
Salts of iron. - Change of valence and of color

CHAPTER XLIX.

LEAD AND TIN.

Distribution of lead. - Poisonous properties. - Some lead
compounds. - Tin

CHAPTER L.

COPPER, MERCURY, AND SILVER.

Occurrence and uses of copper. - Compounds and uses of mercury. -
Occurrence, reduction, and salts of silver

CHAPTER LI.

PHOTOGRAPHY.

Description.

CHAPTER LII.

PLATINUM AND GOLD.

Methods of obtaining, and uses

CHAPTER LIII.

CHEMISTRY OF ROCKS.

Classification. - Composition. - Importance of siliceous rocks. -
Soils. - Minerals. - The earth's interior. - Percentage of elements

CHAPTER LIV.

ORGANIC CHEMISTRY.

Comparison of organic and inorganic compounds. - Molecular
differences. - Synthesis of organic compounds. - Marsh-gas.
series. - -Alcohols. - Ethers. - Other substitution products. -
Olefines and other series.

CHAPTER LV.

ILLUMINATING GAS.

Source, preparation, purification, and composition. - Natural gas

CHAPTER LVI.

ALCOHOL.

Fermented and distilled liquors. - Effect on the system. - Affinity
for water. - Purity

CHAPTER LVII

OILS, FATS, AND SOAPS.

Sources and kinds of oils and fats. - Saponification. - Manufacture
and action of soap. - Glycerin, nitro-glycerin, and dynamite. -
Butter and oleomargarine.

CHAPTER LVIII

CARBO-HYDRATES.

Sugars. - Glucose. - Starch. - Cellulose. - Gun-cotton. - Dextrin. -
Zylonite

CHAPTER LIX.

CHEMISTRY OF FERMENTATION.

Ferments. - Alcoholic, acetic, and lactic fermentation. -
Putrefaction. - Infectious diseases

CHAPTER LX.

CHEMISTRY OF LIFE.

Growth of minerals and of organic life. - Food of plants and of
man. - Conservation of energy and of matter

CHAPTER LXI.

THEORIES.

The La Place theory - Theory of evolution - New theory of chemistry

CHAPTER LXII

GAS VOLUMES AND WEIGHTS.

Quantitative experiments with oxygen and hydrogen - Problems


AN INTRODUCTION TO CHEMICAL SCIENCE


CHAPTER I.

THE METRIC SYSTEM.

1. The Metric System is the one here employed. A sufficient
knowledge of it for use in the study of this book may be gained
by means of the following experiments, which should be performed
at the outset by each pupil.

2. Length.

Experiment 1. - Note the length of 10 cm. (centimeters) on a
metric ruler, as shown in Figure 1. Estimate by the eye alone
this distance on the cover of a book, and then verify the result.
Do the same on a t.t. (test-tube). Try this several times on
different objects till you can carry in mind a tolerably accurate
idea of 10 cm. About how many inches is it?

In the same way estimate the length of 1 cm, verifying each
result. How does this compare with the distance between two blue
lines of foolscap? Measure the diameter of the old nickel five-
cent piece.

Next, try in the same way 5 cm. Carry each result in mind, taking
such notes as may be necessary.

(Fig. 1)

3. Capacity.

Experiment 2. - Into a graduate, shown in Figure 2, holding 25 or
50 cc. (cubic centimeters) put 10 cc. of water; then pour this into
a t.t. Note, without marking, what proportion of the latter is
filled; pour out the water, and again put into the t.t. the same
quantity as nearly as can be estimated by the eye. Verify the
result by pouring the water back into the graduate. Repeat
several times until your estimate is quite accurate with a t.t.
of given size. If you wish, try it with other sizes. Now estimate
1 cc. of a liquid in a similar way. Do the same with 5 cc.

A cubic basin 10 cm on a side holds a liter. A liter contains
1,000 cc. If filled with water, it weighs, under standard
conditions, 1,000 grams. Verify by measurement.

4. Weight.

Experiment 3. - Put a small piece of paper on each pan of a pair
of scales. On one place a 10 g. (gram) weight. Balance this by
placing fine salt on the other pan. Note the quantity as nearly
as possible with the eye, then remove. Now put on the paper what
you think is 10 g. of salt. Verify by weighing. Repeat, as before,
several times. Weigh 1 g., and estimate as before. Can 1 g. of
salt be piled on a one-cent coin? Experiment with 5 g.

5. Resume - Lengths are measured in centimeters, liquids in cubic
centimeters, solids in grams. In cases where it is not convenient
to measure a liquid or weigh a solid, the estimates above will be
near enough for most experiments herein given. Different solids
of the same bulk of course differ in weight, but for one gram
what can be piled on a one-cent piece may be called a
sufficiently close estimate. The distance between two lines of
foolscap is very nearly a centimeter. A cubic centimeter is seen
in Figure 1. Temperatures are recorded in the centigrade scale.

CHAPTER II.

WHAT CHEMISTRY IS.

6. Divisibility of Matter.

Experiment 4. - Examine a few crystals of sugar, and crush them
with the fingers. Grind them as fine as convenient, and examine
with a lens. They are still capable of division. Put 3 g. of
sugar into a t.t., pour over it 5 cc. of water, shake well, boil
for a minute, holding the t.t. obliquely in the flame, using for
the purpose a pair of wooden nippers (Fig. 3). If the sugar does
not disappear, add more water. When cool, touch a drop of the
liquid to the tongue. Evidently the sugar remains, though in a
state too finely divided to be seen. This is called a solution,
the sugar is said to be soluble in water, and water to be a
solvent of sugar.

(Fig 3.)

Now fold a filter paper, as in Figure 4, arrange it in a funnel
(Fig. 5), and pour the solution upon it, catching what passes
through, which is called the filtrate, in another t.t. that rests
in a receiver (Fig. 5). After filtering, notice whether any
residue is left on the filter paper. Taste a drop of the
filtrate. Has sugar gone through the filter? If so, what do you
infer of substances in solution passing through a filter? Save
half the filtrate for Experiment 5, and dilute the other half
with two or three times its own volume of water. Shake well, and
taste.

(Fig 4.)

(Fig 5.) We might have diluted the sugar solution many times
more, and still the sweet taste would have remained. Thus the
small quantity of sugar would be distributed through the whole
mass, and be very finely divided.

By other experiments a much finer subdivision can be made. A
solution of.00000002 g. of the red coloring matter, fuchsine, in
1 cc. of alcohol gives a distinct color.

Such experiments would seem to indicate that there is no limit to
the divisibility of matter. But considerations which we cannot
discuss here lead to the belief that such a limit does exist;
that there are particles of sugar, and of all substances, which
are incapable of further division without entirely changing the
nature of the substance. To these smallest particles the name
molecules is given.

A mass is any portion of a substance larger than a molecule; it
is an aggregation of molecules.

A molecule is the smallest particle of a substance that can exist
alone.

A substance in solution may be in a more finely divided state
than otherwise, but it is not necessarily in its ultimate state
of division.

7. A Chemical Change. - Cannot this smallest particle of sugar,
the molecule, be separated into still smaller particles of
something else? May it not be a compound body, and will not some
force separate it into two or more substances? The next
experiment will answer the question.

Experiment 5. - Take the sugar solution saved from Experiment 4,
and add slowly 4 cc.of strong sulphuric acid. Note any change of
color, also the heat of the t.t. Add more acid if needed.

A substance entirely different in color and properties has been
formed. Now either the sugar, the acid, or the water has
undergone a chemical change. It is, in fact, the sugar. But the
molecule is the smallest particle of sugar possible. The acid
must have either added something to the sugar molecules, or
subtracted something from them. It was the latter. Here, then, is
a force entirely different from the one which tends to reduce
masses to molecules. The molecule has the same properties as the
mass. Only a physical force was used in dissolving the sugar, and
no heat was liberated. The acid has changed the sugar into a
black mass, in fact into charcoal or carbon, and water; and heat
has been produced. A chemical change has been brought about.

From this we see that molecules are not the ultimate divisions of
matter. The smallest sugar particles are made up of still smaller
particles of other things which do not resemble sugar, as a word
is composed of letters which alone do not resemble the word. But
can the charcoal itself be resolved into other substances, and
these into still others, and so on? Carbon is one of the
substances from which nothing else has been obtained. There are
about seventy others which have not been resolved. These are
called elements; and out of them are built all the compounds -
mineral, vegetable, and animal - which we know.

8. An element is a chemically indivisible substance, or one from
which nothing else can be extracted.

A compound is a substance which is made up of elements united in
exact proportions by a force called chemism, or chemical
affinity.

A mixture is composed of two or more elements or compounds
blended together, but not held by any chemical attraction.

To which of these three classes does sugar belong? Carbon? The
solution of sugar in water?

Carbon is an element; we call its smallest particle an atom.

An atom is the smallest particle of an element that can enter
into combination. Atoms are indivisible and usually do not exist
alone. Both elements and compounds have molecules.

The molecule of an element usually contains two atoms; that of a
compound may have two, or it may have hundreds. For a given
compound the number is always definite.

Chemism is the force that binds atoms together to form molecules.
The sugar molecule contains atoms, forty-five in all, of three
different elements: carbon, hydrogen, and oxygen. That of salt
has two atoms: one of sodium, one of chlorine. Should we say "an
atom of sugar"? Why? Of what is a mass of sugar made up? A
molecule? A mass of carbon? A molecule? Did the chemical affinity
of the acid break up masses or molecules? In this respect it is a
type of all chemical action. The distinction between physics and
chemistry is here well shown. The molecule is the unit of the
physicist, the atom that of the chemist. However large the masses
changed by chemical action, that action is always on the
individual molecule, the atoms of which are separated. If the
molecule were an indivisible particle, no science of chemistry
would be possible. The physicist finds the properties of masses
of matter and resolves them into molecules, the chemist breaks up
the molecule and from its atoms builds up other compounds.

Analysis is the separation of compounds into their elements.

Synthesis is the building up of compounds from their elements.

Of which is the sugar experiment an example? Metathesis is an
exchange of atoms in two different compounds; it gives rise to
still other compounds.

A chemical change may add something to a substance, or subtract
something from it, or it may both subtract and add, making a new
substance with entirely different properties. Sulphur and carbon
are two stable solids. The chemical union of the two forms a
volatile liquid. A substance may be at one time a solid, at
another a liquid, at another a gas, and yet not undergo any
chemical change, because in each case the chemical composition is
identical.

State which of these are chemical changes: rusting of iron,
falling of rain, radiation of heat, souring of milk, evaporation
of water, decay of vegetation, burning of wood, breaking of iron,
bleaching of cloth. Give any other illustrations that occur to
you.

Chemistry treats of matter in its simplest forms, and of the
various combinations of those simplest forms.

CHAPTER III.

MOLECULES AND ATOMS.

9. Molecules are Extremely Small. - It has been estimated that a
liter of any gas at 0 degrees and 760 mm. pressure contains 10^24
molecules, i.e. one with twenty-four ciphers.

Thomson estimates that if a drop of water were magnified to the
size of the earth, and its molecules increased in the same
proportion, they would be larger than fine shot, but not so large
as cricket balls.

A German has recently obtained a deposit of silver two-millionths
of a millimeter thick, and visible to the naked eye. The computed
diameter of the molecule is only one and a half millionths of a
millimeter.

By a law of chemistry there is the same number of molecules in a
given volume of every gas, if the temperature and pressure are
the same. Hence, all gaseous molecules are of the same size,
including, of course, the surrounding space. They are in rapid
motion, and the lighter the gas the more rapid the motion. This


1 3 4 5

Online LibraryRufus Phillips WilliamsAn Introduction to Chemical Science → online text (page 1 of 5)