LIBRARY
OF THE
UNIVERSITY OF CALIFORNIA.
Class
PRINCIPLES
OF
CHEMISTRY;
EMBRACING THK MOST
RECENT DISCOVERIES IN THE SCIENCE,
AND
THE OUTLINES OF ITS APPLICATION TO AGRICULTURE
AND THE ARTS.
X
ILLUSTRATED BY NUMEROUS EXPERIMENTS,
NWWLY ADAPTED TO THE SIMPLEST APPARATUS.
BY JOHN A. PORTER, M.A., M.D.
PROFESSOR OF AGRICULTURAL AND ORGANIC CHEMISTRY IN YALE COLLEGE.
NEW YORK:
A. S. BARNES & CO., 51 & 53 JOHN-STREET,
I860.
*
Entered according to Act of Congress in the year 1856, by
JOHN A. PORTER,
in the Clerk's Office of the District Court for the District of Con-
necticut.
IN the preparation of this text-book on Chemistry, it has
been the design of the author to disencumber the subject
of much detail, which is only of interest to the professional
chemist, and at the same time to bring the illustration of the
more important phenomena of the science within the reach
of every school and every individual student.
The most distinguished philosophers have not deemed it
beneath their dignity to employ the simplest means of inves-
tigation. The teacher will not be loth to take advantage of
similar means in illustrating their discoveries. An important
design of this work is to show how this object may be ac-
complished, by the simple addition of a few test-tubes and a
spirit lamp, to a list of chemical apparatus which may be
found in every house.
Among the other distinctive features of the work, are a
more complete classification than usual according to chemi-
cal analogies, the explanation of chemical phenomena in
ordinary language, as well as symbols, and the addition of
a complete set of formulae in the Appendix. A number of
recent and important discoveries are introduced, and the
relations of Chemistry to the Arts and Agriculture, are es-
pecially considered.
The method adopted for the explanation of chemical phe-
nomena, while it is believed to be more effectual in imparting
the leading idea of all chemical reactions, leaves to the
1
11 PREFACE.
student the useful exercise of constructing formulae. He
is at the same time supplied in the Appendix with a com-
plete control of his results. This part of the work contains
in addition, numerous tables, and other supplementary mat-
ter for the use of the more advanced student
The language of the atomic theory has been rigorously
adhered to throughout the work, as the best expression
of our present knowledge of the constitution of matter.
While it is liable to no objection which does not hold against
the language of every department of Physics, its uniform
employment has the great advantage of accustoming the mind
to a conception which furnishes a probable explanation of the
most obscure portions of the science.
Several topics introduced in the chapters on Physics, are
designed simply as introductory to other subjects, and are
very briefly treated, in accordance with this design.
Among the numerous authorities consulted in the prepa-
ration of this work, the author would especially mention the
works of Berzelius, Liebig, Gmelin, Gregory, Regnault,
Payen, Graham, Silliman and Stockhardt. He would also
take this opportunity of acknowledging the important aid
extended by his able professional assistant, DR. ROBERT A.
FISHER, both in the execution of his design for a simplified
course of experiment, and for valuable information in rela-
tion to several processes of applied chemistry.
Boxes containing apparatus and materials neatly put up to accom-
pany this work, may be ordered of J. R LTJHME, & Co., dealers in
Chemical Apparatus and Pure Chemicals, No. 556 Broadway, New
York. Price $6.00.
The list embraces all the articles named on the last page of the work,
with the exception of those marked with an asterisk, which may be
procured of any druggist.
TABLE OF CONTENTS.
PART I.
PHYSICS.
PAGE
ATOMS AND ATTRACTION, ... 11
LIGHT. — Chemical action of
Light, 15
Theories, 15
Laws, ...... 17
Analysis of Light, . . 22
HEAT. — Nature and Sources, 25
Communication of Heat, 30
Changes effected by Heat, 48
HEAT. — Expansion,
PAGE
.... 50
.... 61
Vaporization, .... 66
Boiling, ...... 77
ELECTRICITY AND MAGNETISM, . 99
Galvanism, ..... 103
Batteries, ...... 114
Galvanic Decomposition, 117
Magnetic Telegraph, . .124
PART II.
CHEMICAL PHILOSOPHY.
ELEMENTS, .
MIC CONSTITUTION, .
EXPLANATION OF SYMBOLS,
LAWS OF COMBINATION, . ,
PAGE
. 129
129
. 132
134
PAGE
PROPERTIES OF ACIDS AND BASES, 137
EFFECT OF SOLUTION, . . . 138
ELECTRICAL CONDITION OF THE
ELEMENTS, 138
IV
CONTENTS.
PART III.
INORGANIC CHEMISTRY.
FAQE
METALLOIDS.
Oxygen, 141
^.Ghlorine, 149
/Modine, 156
Bromine, 158
-^'.--Fluorine, 158
/ Sulphur, 159
Nitrogen, 169
Phosphorus, . . . .176
Arsenic, 179
Carbon, 185
Boron, 197
METALS. — Classification, . .231
CLASS I. — Potassium, &c. 233
CLASS II. — Barium, <fec. . 237
PAGE
METALS.
CLASS III— Iron, &c. . 240
CLASS IV. — Tin, &c. . 243
CLASS V.— Bismuth, &c. 259
CLASS VI. — Mercury, <fec. 258
SOLUTION AND CEYSTALIZATION, 274
Precipitation, .... 275
Variety of Crystals, . 279
Forms of Crystals, . . 280
Isomorphism, .... 284
OXIDES, 285
CHLORIDES, 294
SALTS, 300
THE DAGUERREOTYPE, . . .327
CHEMICAL ANALYSIS, . . .332
PART IV.
ORGANIC CHEMISTRY.
GENERAL VIEWS 335
VEGETABLE CHEMISTRY, . . 345
Wood, 349
Starch, 357
Sugar, 359
Alcohol, 362
Organic Acids, . . 372
Essential Oils, . . . 379
Artificial Essences, . .382
Resins, .... , 383
PAGE
VEGETABLE CHEMISTRY.
Protein Bodies, .... 388
Organic Bases, . . . 395
Coloring Matters, . . . 3*96 <
Dyeing, 397
Calico Printing, . . . 400
AGRICULTURAL CHEMISTRY, . 402
ANIMAL CHEMISTRY, . . . .413
ORGANIC ANALYSIS, . . . . 430
CIRCULATION OF MATTER, . 433
IISTTRODUOTION.
ACCORDING to the most ancient view of the constitu-
tion of matter, the earth and all material things are but
modifications of one and the same original substance.
Fire, water, and air, were each in turn asserted to be
the primitive element, according to the arbitrary con-
jecture of philosophers who were bold enough to spec-
ulate upon the subject. At a later date, the views of
all seemed to be harmonized in ascribing the same
dignity to the three contending elements, and including
earth among the original varieties of matter. Earth,
Air, Fire, and Water, were assumed to be the original
materials out of which all forms of matter are produced.
Modern chemistry has dethroned each of these ele-
mental monarchs of the world, and distributed their
prerogatives among a larger number. Earth, air, and
water, are all excluded from the list of elements, and
6 INTRODUCTION.
fire appears in the modern view as only the transient
attendant of chemical combination.
Each one of the acknowledged elements has its own
specific properties, affinities, and capacity of combina-
tion. These peculiarities, and all resulting phenomena,
it is the province of chemistry to investigate and ex-
plain. Light, heat, and electricity, stand in intimate
relation to all chemical action, either as cause or effect,
or unfailing attendant, and are therefore briefly consid-
ered in the earlier part of the present work.
The study of science has not for its object the mere
gratification of an idle curiosity. Looking at the sub-
ject from a material point of view alone, chemistry is
one of the great agents in the transformation of nature,
and its subjugation to the wants of man. The earth
yields her treasure to its skillfully conducted processes,
and even the trodden clay becomes converted in its
crucible into shining metal. The arts draw from it,
with every succeeding year, increased advantage, and
the condition of mankind is elevated, and the world
advanced by its progressive triumphs. Agriculture
also is indebted to its discoveries. It opens to us mines
of agricultural wealth in what would otherwise have
passed for worthless refuse. It clothes exhausted fields
with new fertility, by the addition of some failing con-
stituent whose absence its subtle processes have de-
tected. It carefully investigates the laws and condi-
INTRODUCTION. 7
tions of vegetable growth, by which earth and air are
converted into food for man and beast, and thus places
us on the highway of sure and rapid improvement.
These practical results, which are the "basis of that
material prosperity in which taste, and literature, and
the graces of life find their natural growth, are "by no
means to be disregarded. But this is not all. The
study of chemical science reveals to the mind a beauty
and harmony in the material world, to which the unin-
structed eye is blind. It shows us all of the kingdoms
of nature contributing to the growth of the tiniest plant,
and feeding the germ, as it were, by the inter-revolution
of their separate spheres. It shows us how through
fire; or analogous decay, all forms of life are returned
again to the kingdoms of nature, from which they were
derived. Without encroaching upon the domains of
the astronomer, it reveals to us still more wonderful
relations of distant orbs, which affect not only the out-
ward sense, but supply the very forces which we em-
ploy in our contest with the powers of nature. It un-
veils to us a thousand mysteries of cloud and rain, of
frost and dew, of growth and decay, and unfolds the
operation of those silent yet irresistible forces which
are the life of the world we inhabit.
But the study of nature is worthy of being pursued
with a still nobler aim. The glory of the Deity shines
in every crystal and blooms in every flower. Every
8 INTRODUCTION.
atom is instinct with a life which the Creator has im-
parted. The laws that govern minutest particles, as
well as the grander revolutions of the heavenly spheres,
are but the expression of His will. The reverent study
of nature is therefore a contemplation of Deity. Vague
and unsatisfactory without the aid of another, and
written revelation, it unfolds to the mind thus enlight-
ened, new and exalting evidences of the infinite wis-
dom and beneficence of the Creator of the world.
1. THE Science of Chemistry is of the
rrnstry tell us .
of Earth, Air, widest range. Air, Earth, Fire, and Water,
Fire, and Wa- all belong to its domain.
It informs us of the composition of the rocks which
make up the mass of the Earth, and of the soil
which forms its surface. It tells us of what Air is
made, and how it supplies the wants of animal and
vegetable life. It separates Water into gases, and re-
produces it again by uniting them. It informs us of
the nature of Fire, and of the changes which take
place in combustion.
2. It tells us of what plants are formed,
What of met-
als,piants,and and what becomes of them when they
decay and disappear. It tells us how to
produce metals from ores, wines from fruit, liquors
from grain, and shows us the changes which take place
in the formation of all these substances. Almost all
transformations which occur in the materials around
us, as, for example, of iron into rust, of wood or coal
into gas, of food into flesh, it belongs to Chemistry to
describe and explain.
3. As all of these changes result from
Wliy does it *'«'"• • , /.
treat of at- the action oi the minute particles 01 mat-
ter on each other, it is necessary first to
consider the subject of Atoms.
1*
10 INTRODUCTION.
Why of Heat 4. As the most of them depend on changes
and light? _ . .
of temperature, it is necessary in the first
part of the work to consider the laws and effects of
Heat. As these laws are best understood from their
analogy to the laws of Light, and as Light has an import-
ant influence in many chemical processes, a brief chapter
on Light precedes the chapter on Heat and its various
effects.
5. As many, and perhaps all chemical
Why is Elec- . . t ,
tricity intro- changes, are accompanied by electrical
duced? phenomena, it is also important to dwell
briefly on the subject of Electricity before proceeding
to what is more strictly the science of Chemistry.
The first part of this work is, therefore, devoted to the
consideration of these subjects ; or, in other words, to
the Science of Physics.
I.-FHYSICS.
CHAPTER I,
ATOMS AND ATTRACTION.
Of what is 1* ATOMS. — All matter is supposed to be
matter compo- composed of exceedingly minute spherical
sed? What , •
is said of or spheroidal particles, which are held to-
gether by their mutual attraction, and are
never themselves subdivided. These particles are com-
monly called atoms. There is reason to believe that
the atoms of different substances differ from each other
in weight and perhaps in size. The belief that they
are never subdivided is not based on their extreme
minuteness, but on other grounds, to be mentioned
hereafter.
2. MINUTENESS OF ATOMS. — Their mi-
How is the mi-
nutcnessofat- nuteness is shown by the fact that a sin-
oms shown? glg gmin Qf mugk wm fiu ft rOQm with
its fragrant particles for years, without suffering any
considerable loss of weight. The number of atoms it
gives off during that time is beyond computation.
4. ELEMENTS. — There are at least sixty
Define and il- W ;" ,
lustrate an ele- different kinds of matter. Each kind which
cannot be separated into other kinds is called
an elementary substance, or simply an element. Iron
12 ATOMS.
and carbon or charcoal are elements. Iron rust, on the
other hand, is a compound. There are, of course, as
many different kinds of atoms as there are of elements.
5. COHESION. — The force which binds
What is Coke- r . , . -. . i, j
sion? lllus- together atoms of the same kind is called
trate the sub- fae attraction of cohesion, or simply co-
hesion. In the more tenacious substances?
such as iron or copper, the force of cohesion is im-
mense. The strength of a horse is insufficient, for ex-
ample, to break an iron wire one-fourth of an inch in
thickness. It is because in every section of the wire
the atoms attract each other with a superior force. And,
as we may easily imagine a thousand sections in every
inch of the wire, we may see that there is in every inch
a force of attraction constantly exerted superior to the
strength of a thousand horses. Attraction between un-
like atoms in contact with each other, as between glue
and the wood to which it is applied, is called adhesion.
6. GRAVITATION. — Unlike the force of
Station™™' attraction mentioned in the preceding para-
graph, gravitation acts at all distances. It
is the reason of the weight of bodies, one body weigh-
ing twice or three times as much as another, because it
has twice or three times the quantity of matter to at-
tract and be attracted by the earth.
7. CHEMICAL ATTRACTION OR AFFINITY.
What ^s Che-
mical Attrac- The force which unites unlike atoms into
twn or Affim- compOUn(is possessing new properties is
called chemical attraction or affinity.
Thus iron and oxygen unite by chemical attraction to
form iron rust, a substance different from either. So
ATOMS. 13
the gas chlorine ana the metal sodium unite, as will be
hereafter seen, to form common salt. When substances
become thus united by chemical affinity, the resulting
compound is not a mere mixture, with properties of
both constituents, as when salt and sugar are mixed ;
it is, on the contrary, a new substance with properties
of its own.
8. DISTANCE OF ATTRACTION. — The forces
Do the forces , , , . ., t
of Cohesion P* attraction above mentioned, with the ex-
and Chemical ception of gravitation, act only at immeasu-
Affimty act at J
great dlstan- rably small distances. Two plates of glass
an inch apart do not attract each other ; even
when brought close together they will not remain at-
tached. But if powerfully pressed, the atoms are brought
within the range of the force of cohesion, and cannot
again be separated. So iron and oxygen will not at-
tract each other from a distance, but when brought to-
gether, unite in consequence of their chemical attraction.
9. ILLUSTRATION. — The action of the three
Illustrate the .
three different is illustrated in a falling drop of water. Al-
ktractSionf "^ ^n^y nolds togetner tne atoms of oxygen
and hydrogen which make up each particle
of water. Cohesion unites the particles of water thus
formed, to make the drop, and gravitation causes the
coherent drop to fall.
10. THREE STATES OF MATTER. — There
What are the f
three states of are three distinct states or conditions 01
matter? matter — the solid, the liquid, and the gas-
eous, and almost all substances may be made to assume
each of these states. Thus, a piece of solid sulphur,
if heated up to a eertain point, melts and becomes
14 ATOMS.
liquid. If the liquid sulphur be exposed to a still higher
temperature, it passes off in the form of a vapor or gas.
11. CONTACT OF ATOMS. — The atoms
Are atoms in of matter are not supposed to be in ab-
contact ?
What is the solute contact in either solids, liquids,
of or gaseS" This is lnferred fr°m the fact
cohesion in bo- that all substances may be diminished in
bulk by pressure. But in solid bodies the
attraction of cohesion between the atoms is strongest,
and they are more nearly and firmly bound together.
In liquids, cohesion is less than in solids, and the atoms
are farther separated. In gases, cohesion is entirely
overcome, and but for gravity, the atoms would sepa-
rate themselves indefinitely.
Heat is the main cause of this difference in cohesion.
This subject will be more fully considered in the chap-
ter on Heat or Caloric.*
* The subject of crystalization belongs to Physics, and in a strictly
scientific arrangement, would be considered at this point. The student
will find the most accessible illustrations of the subject in the Salts,
which are considered later in the work, and it has therefore been in-
troduced in the chapter which treats of these compounds. It is to be
borne in mind that what is there stated, relates to other compounds
and to elementary substances, as well as to salts.
LIGHT. 15
CHAPTER II.
LIGHT.
12. CHEMICAL ACTION OF LIGHT. — Da-
Jn what cases
does light act guerreotype pictures are produced by the
chemically? chemical action of light< So Hght actg
chemically in converting water and irhe carbonic acid
of the air into vegetable matter. The action of light
in these cases will be explained hereafter. The present
chapter is devoted to the consideration of its nature and
more important laws.
13. LIGHT is WITHOUT WEIGHT. — While
wefht? Uffki the effects of tight* and the laws according
to which they take place are well under-
stood, philosophers differ with respect to its nature. It
is, however, agreed that light is imponderable, or without
weight, this being inferred from the fact that an illu-
mined object weighs no more than the same object
when unillumined.
14. NEWTON'S THEORY. — Newton main-
What is New- . . /i • i i •
ton's theory ? tamed that light is a fluid thinner or more
Nation of sTglt Sllbtle than ^ OT **? ^ but Composed
produced?- like these of minute particles, constantly
given off from the sun and all luminous objects. He
supposed that it is this substance passing into the eye
that produces the sensation of sight, as the fine particles
of fragrant matter, passing off from flowers, produces
the sensation of smell.
16 LIGHT.
15. THEORY OF VIBRATION. — Another
What is the view is that the fluid above described does
other view of
the nature of not pass from the sun and other luminous
objects to the eye, but fills the space be-
tween them and serves as a medium for producing the
sensation of light, as the air does for producing sound.
TJ, . .,. 16. When a bell is struck its vibrations
Illustrate this
view ? are communicated to the air, and so to the
ear, producing the effect of sound. So, according to the
view of light last mentioned, vibrations are caused by
some means in the sun and certain other bodies, which
being rapidly transmitted through the fluid above men-
tioned, produce, when they fall on the eye, the sensa-
tion of light.
17. EXISTENCE OF THE SUPPOSED FLUID.
How is this
fluid known to Such a fluid as this theory requires is known
to exist in the spaces between the heav-
enly bodies, by the influence which it exerts on their
motions, and is supposed to pervade all substances, whe-
ther solid, liquid or gaseous, occupying the spaces be-
tween their pores. It is called ether, but has no rela-
tion to the chemical and medicinal liquid of the same
name.
18. BOTH VIEWS EXPLAIN THE FACTS. —
ther view ex- For tne explanation of most of the facts
^rac~ and laws of light it; matters little which
view is taken. Thus, it is certainly true
that light is reflected from mirrors, whether we suppose
it a subtle fluid, and that its reflection is the glancing
off of its particles from the polished surface, as a ball
thrown obliquely against the side of a house glances
/ OF THE \
f UNIVERSITY )
LIGHT. 17
off from it, or whether we suppose it to consist of vi-
brations, which are made to glance off as the vibrations
of the air in the case of echoes.
19. The first, or Newtonian theory, ena-
advantagl of ^es us to explain the leading facts more
the Newtonian simply and clearly, and is therefore em-
theory ? . .
ployed in this work for this purpose. The
definitions and laws of light are stated in the language
of that theory.
What is a ray 20. RAY AND MEDIUM DEFINED. A ray
°lustrate ? the °^ ^§nt *S a ^me °^ Partic^S of light. In
subject. such rays or lines of particles, light is con-
stantly passing off from all visible objects. From every
part of the book before the student, for example, it
passes into the eye, enabling him to know the nature
of the object. If the book be taken into a dark room
it is no longer visible, because it obtains no light which
it may afterward reflect to the eye.
W1 , . A medium is any space or substance
w liat is a me-
dium? through which light passes.
n. .-, , 21. LAWS OF LIGHT. — The more im-
Give the laws
of light ? portant laws of the radiation of light are
the following :
1. Rays of light proceed from ev-
ery point of luminous objects in every
direction. They proceed, for exam-
ple, from every point of the sun's sur-
face.
2. They proceed in straight lines. Light, for example,
comes to us in straight lines from the sun.
3. They diverge as they proceed. This is illustrated
18 LIGHT.
in the figure, the central point being supposed to be
a star or other source of light.
22. DIVERGENCE OF
Explain the
divergence of LIGHT. By the diver-
rays of light. gence of rayg Qf Hght
is meant that they spread them-
selves over more space, the further they proceed from
their source. This is illustrated in the figure, where
the light of a candle is represented as passing through
a window, and illumining a larger space on the opposite
wall.
23. LAW or DIVERGENCE. — When the dis-
Give the law of .
divergence,and tance is doubled, the surface that light
illustrations. win coyer ig quadrUpled. This is also
illustrated in the figure. The wall being twice as far
from the candle as the window, the light covers four
times the surface. If the distance of the wall were
three times that of the window, the surface covered
would be nine times as large as the window ; if four
times, the surface covered would be sixteen times as
large. It is evident from these figures that the surfaces
covered, increase as the squares of the distances. The
light, of course, diminishes in intensity in the same
proportion, as it is thus spread over greater surface. At
four times the distance, it has only one-sixteenth the
intensity, and so on.
24. REFLECTION OF LIGHT. — If a ball of
Explain the .
reflection of ivory or other material be thrown perpen-
dicularly against any hard plane surface, it
will return in the same line ; if it be thrown obliquely,
LIGHT. 19
it will glance off with the same degree of ob-
liqueness in the other direction. Light is re-
flected from plane surfaces in the same manner.
This reflection is illustrated in the figure,
which represents a mirror, and a ray of light
falling upon it and again re-fleeted.
25. APPARENT PLACE CHANGED BY RE-
Explam the FLECTION. — As we always seem to see an
change of ap-
parent place object in the direction from which its rays
by reflection. . , . . .
enter the eye, a mirror which changes the
direction of the rays will change the apparent place
of the object. Thus, if the rays of the sun fall oblique-
ly upon a mirror, and are reflected to the eye, we shall
seem to see the sun in the mirror, in the direction
which the rays have acquired after reflection.
26. CONCAVE MIRRORS. —
Tf tirZl On considering that rays are
converge rays reflected from plane surfaces
with the same degree of ob-
liquity with which they fall upon them,
we shall be able to comprehend how it is
that concave mirrors have the property of converging
rays of light, or bringing them together in a point.
A number of small plane mirrors, situated obliquely
toward each other, as represented in the figure, and as
they might be arranged in a bowl or saucer, would
evidently have this effect. As a concave mirror may
be regarded as made up of innumerable plane mirrors,
similarly arranged, it would obviously be productive of
the same effect.
20 LIGHT.
27. REFRACTION. — Re-
fc£ion?Re~ fraction is the change of
direction which a ray expe-
riences in passing obliquely from a rarer
into a denser medium, or the reverse.
28. The figure represents a block of glass,
£r^am the ftnd shows tne direction which a ray -of
light would take on entering and emerging
from it. On entering, it makes a bend, and passes on
through the glass less obliquely ; that is, more nearly in
the direction of a line drawn perpendicularly to the sur-
face of the glass, and continued through it. On passing
out again it would be bent away from such an imagina-
ry perpendicular line, and re-assume its previous course.
29. ANOTHER STATEMENT OF THE LAW.- —
Give another
statement of As the perpendicular has only an imagina-
YY existence? ^ ig perhaps easier to fix in
the mind the changes of direction of rays
passing in and out at regular surfaces thus : A ray, on
entering a denser medium pursues within it a course fur-
ther from the nearest portion of the surface than its origi-
nal course would be if continued. And a ray entering a
rarer medium takes a course nearer the nearest portion of
the surface than its original course would be if continued.
These statements are true for all plane or uniformly
curved surfaces.
30. ILLUSTRATION. — A
Illustrate by a com placed m ft tea_cnpj ag
represented in the figure,
so as to be barely concealed from the
eye, will be rendered visible by filling the cup with water.
LIGHT. 21
The surface of the water furnishes a point of transi-
tion from a denser to a rarer medium, and the direction
of the ray is thereby changed in accordance with the
law above stated. It is thereby enabled to turn a cor-
ner, as it were, and come to the eye.
31. TRIANGULAR PRISM. — Bearing the
What effect ^
has a prism on rules last given in mind, it will be readily
arayof light?
ing through a prism must be such as is
represented in the figure. The ray may
be supposed to start from below or above
the prism. The line of its passage through
the glass will be the same in either case.
32. Let us suppose it to pass upward
Mustrate the from a bit Qf white paper Qr other object to
the eye of an observer above. The appa-
rent place of the object will be changed. It will be seen
still beneath the prism, not where it actually is, but in
the direction in which the ray points as it enters the
eye. This experiment may be made equally well
with the water prism described in the next paragraph.
33. CONSTRUCTION or A PRISM.
How may a
prism be con- The prism commonly used in
optical experiments is of solid
glass. In lack of this, its place may be rea-
dily supplied by the water prism represented in the fig-
ure. A strip of window glass is to be scratched with a
file and broken into three pieces of equal length. These
are set up, as represented in the figure upon another bit
of glass previously warmed, and thickly covered with
sealing wax. When the wax is cooled, and the bits
22 LIGHT.
of glass which it holds will stand alone, the corners
where they meet are also closed with sealing wax.
The prism is then filled with water, taking care not to
moisten the upper edges, and a glass top is afterward
attached by wax.
34. ACTION OF THE
Explain the LENS — The property
action of the A
convex lens. which a COI1V6X lens pOS-
sesses of converging rays
of light and heat, and bringing them
together in a point, is also a consequence of refraction.
All of the rays which fall upon its surface are bent, as
shown in the case of the prism ; but, owing to its shape,
they are bent in diiferent degrees and directions, so that
they all meet in a point. This point is intensely
bright if brought on a dark object, and is called the
focus.
35. There is another law of refraction
Explain ano- . •»'•*••»•
ther law of which has not been stated, which is essen-
tial to a full understanding of the convex
lens. According to this law, the more obliquely a ray
falls upon any surface the more it is refracted or bent out
of its course. And it is a consequence of the shape of the
lens, and its greater steepness toward the edge, that of
all the parallel rays which fall upon its surface, those
which fall furthest from the center fall most obliquely,
and enter the air again more obliquely. In proportion,
therefore, as they need to be bent to be brought to the
focus, they are thus bent by the action of the lens.
36. ANALYSIS OF LIGHT. — It has, up to
cometed i- ^is point, been assumed that light is sim-
LIGHT. 23
pie in its nature, but it may be proved by experiment
that every beam of white light such as we receive from
the sun is made up of rays of different colors.
37. This maybe done by holding a prism
How is- its .
composition in the sun and al-
Proved? lowing the light
to pass through it and fall
upon an opposite wall or
screen. A beautiful parti-colored spot will be produced,
called the solar spectrum. The beam of light which
enters the prism is separated by it into rays of seven dif-
ferent colors. The experiment, if performed in a dark
room, into which light is admitted through a very small
opening, is extremely beautiful.
38. The rays, before entering the prism,
How does re- ° . r
fraction de- passing along together parallel with each
compose light? other? form white H ht . but on entering
the glass and emerging from it, each of them is
refracted or bent out of its course in a different degree,
and they are thus separated, and made to appear with
their own colors. Why one ray is refracted more than
another is not known. The above experiment proves
it to be a fact, and this is all our knowledge on the
subject.
Do lenses de- 39. LENSES DECOMPOSE WHITE LIGHT
compose light? AND RECOMBINE THE RAYS. — This separation
of white light into colored rays occurs always when
light passes through a prism ; but, for the sake of sim-
plicity, this fact was left out of consideration in para-
graph 29, the object in that place being simply to
show the general direction of the light as it passes
24 LIGHT.
through the prism. Such separation also occurs when
light passes through a lens, but the different colored
rays on emerging again from different points of the
lens overlap each other, and are in great part united
again to form white light.
NATURE OF HEAT. 25
CHAPTER III.
HEAT.
Section 1. — Nature and Sources of Heat.
Has heat 4Q. NATURE OF HEAT. — It was remarked
weiqht? Give . ,
an Illustration in the commencement 01 the chapter on
light, that philosophers, although acquainted with its
facts and laws, differed in opinion as to its nature. The
same is true of heat. It is agreed, however, that heat,
like light, is imponderable, or without appreciable
weight ; this being known from the fact that a heated
body weighs no more than a cold one.
41. If the end of a bar of iron is heated, the
other end soon becomes hot. There is no doubt
as to the effect, and it would seem that something
must have passed from the fire, along through the
rod to produce it. But we do not certainly know
that any substance has been thus transmitted. It may
be that heat is analogous to sound, and produced by
vibrations. Being thus in doubt, we say that the na-
ture of heat is not understood.
42. MECHANICAL THEORY. — One view is
State the me- . • r- ^
chemical theo- that a very subtle fluid coming from the
ry' fire has actually passed along through the
mass of metal, and from that into the hand, and so
caused the sensation of warmth or heat. And this
supposed substance is called heat, or caloric.
2
26 HEAT.
What is the 43. THEORY OF VIBRATION. — Another
bration? view, corresponding to the second view ol
light, is, that heat is not a fluid, but, like light, the result
of vibration in the ether which is every where present.
The vibrations which produce the sensation of heat
are, of course, different from those which produce that
of light, as the movements of the air which produce
heavy and sharp sounds are different. We must sup-
pose, indeed, in the former case, that a much greater
difference exists. But it is assumed that both are the
result of vibrations of some kind.
44. ILLUSTRATION. — When a bell is struck
Give the illus- ^s vibrations are communicated to the air,
tration.
and so to the ear, producing the effect of
sound. So, according to this view, vibrations of a pe-
culiar kind are caused by some means in the sun, and
all sources of heat, and, being rapidly transmitted
through the ether, produce, when they fall upon our
bodies, the sensation of heat. So the bar heated at
one end becomes hot at the other, because certain vi-
brations, originated in the fire, are gradually transmit-
ted through the ether, and the iron which it pervades,
to the other end.
45. THE FACTS ARE DEFINITELY KNOWN.
What is the
limit of our It may seem strange to the reader that
Cct?° there should be this doubt in relation to so
common a subject as heat. But there is a
similar limit to our knowledge in most of the sciences.
In physiology, for example, we know that muscle, and
bone, and other parts of the body, are produced from
the blood, and that life, or vital force, is essential to
SOURCES OF HEAT. 27
their production ; but how the vital force operates we
do not know. But, as in physiology this ignorance
does not prevent us from comprehending the structure
of the human body and the uses of its different organs,
so ignorance in relation to the nature of heat does not
interfere with the acquisition of the most perfect knowl-
edge of its effects, and the laws according to which
they happen.
46. THE MECHANICAL THEORY HERE
What theory T ,, , ~
is adopted in ADOPTED. — In the present volume the for-
mer Of the views which have been men-
Explain it.
tioned is adopted, and heat, like light, is
assumed to be an exceedingly subtle imponderable fluid.
And, to return to the example of the heated bar, it grows
hot at the end farthest from the fire because the fluid
actually passes through its solid substance, and is so
communicated to the hand.
47. DEFINITION OF COLD. — Cold is a
what is meant
by the term relative term signifying the comparative
absence of heat. But the coldest bodies
which we know of, as ice, for example, contain heat,
and may be made colder by its withdrawal.
48. SOURCES OF HEAT. — The principal
State the prin-
cipal sources sources or heat are the sun and fixed stars,
of hmt. chemical action, electricity, and friction.
It is by no means certain that these should be distin-
guished as different sources ; for the heat of the sun
may be due to chemical action, and electricity is, as
we know, excited both by chemical action, and by
friction.
28 HEAT.
Hmmuchheat 49. Q.UANTITY OF HEAT THE SUN SENDS
does the. sun ,
send to the TO THE EARTH. — The sun sends enough
earth? jieat to tne eartn every year to melt a shell
of ice enveloping the earth a hundred feet thick. This
may be ascertained by observing what thickness the
average heat of the sun will melt per minute, and then
calculating the quantity for a year. The method ac-
tually pursued is slightly different from this, but the
same in principle. The sun, in fact, sends a larger
amount of heat to the earth than is above stated, but
40 per cent, of it is absorbed by the atmosphere. The
quantity above given is the remaining 60 per cent.
50. TOTAL QUANTITY OF HEAT THE SUN
Howmuchheat .
is given out by GIVES OUT. KllOWlllg flOW much COniCS
the sun audits t th th d it atmosphere, it is easy
atmosphere ? *
to calculate how much starts from the sun.
It is just in proportion to the extent of the whole visi-
ble heavens, as seen from the sun, compared to the space
occupied by the earth, as seen from the same point.
By making the calculation it is ascertained that a
quantity of heat is given out from the sun in a year
which, if it all came to the earth, would melt a crust
of ice nearly 4000 miles thick, or a quantity which
would melt every minute a crust nearly thirty-seven
feet in thickness. But the heat of a blast-furnace,
if kept up constantly to the highest point, would melt
'but a little over the thickness of five feet of ice per min-
ute. The sun's surface is, therefore, more than seven
times as hot as the glowing surface of the fire of a
blast-furnace.
SOURCES OF HEAT. 29
What is said 51. HEAT OF THE FIXED STARS. The
of the heat of
fixed stars? fixed stars are suns of other systems, and
sources of heat, like our own sun. And their number
is so great, that notwithstanding their distance, they
exert a very important eifect on the temperature of
the earth. It is estimated that they give us nearly as
much heat as the sun, and that without this addition to
the sun's heat, neither animal nor vegetable life could
exist upon the earth.
52. HEAT OF CHEMICAL ACTION AND
Give examples
of heat pro- ELECTRICITY. — We shall see hereafter that
mic'al ^action heat ls evolved in almost al* Cases of che-
and by elcc.tri- mical action. Indeed, the heat of our fires
has this origin, as will be explained in an-
other chapter. The heat of the lightning is devel-
oped by electricity.
Give examples 53. HEAT FROM FRICTION. The heat
°f jj*j* P££ produced by slight rubbing is sufficient to
tion. set on fire a phosphorus match. Sir
Humphrey Davy produced heat by friction between
two pieces of ice. It is said that Indians produce fire
by rubbing two sticks of wood together. Count Rum-
ford caused water to boil by boring a cannon beneath its
surface. These are all cases of the production of heat
by friction.
30 HEAT.
Section 2. — Communication of Heat.
54. Heat is communicated by conduction, convection,
and radiation. These three modes of communication
will be considered in the order in which they are
named.
CONDUCTION.
Explain the 55. Conduction is the passage of heat
%£*uction f through a body by communication from
particle to particle. An iron wire, one
end of which is held '
o o o o o o ^
in aflame, soon grows Q
hotter at the other, by conduction of the heat of the
flame. The progress of heat along a wire may be
shown by fastening marbles to it with wax, as rep-
resented in the figure, and then heating one end by a
lamp. The marbles drop off successively, as the heat
in its progress melts one bit of wax after the other.
The communication of heat from one body to another
in contact with it is also a case of conduction.
56. WHEN CONDUCTION CEASES. — Con-
When docs
conduction duction proceeds toward the cooler por-
tions of a body until all its particles be-
come equally hot, just as the absorption of water by a
sponge continues until all its pores are filled. This
point being reached, there is no tendency to further
motion in the case of the heat more than in water.
57. THE METALS ARE THE BEST CON-
W hat substan-
ces are the best DUCTORS. — -The earths and wood conduct
very slowly; fine fibrous substances, like
CONDUCTION. 31
wool, cotton, fur, and feathers, slowest of all. Liquids
and gases, as will be hereafter seen, are non-conduct-
ors of heat. The superior conducting power of metals
is shown in the rapidity with which an iron wire, one;
end of which is held in the flame of a lamp, grows hot
at the other end. A splinter of wood, or a pipe-stem,
is heated from end to end much less rapidly, while
scarcely any heat would be communicated along a roll
of cotton cloth, one end of which was inflamed.
58. ILLUSTRATION. — The difference of
How may the - m
conducting conducting power in metals and earths may
al™L°fbeieii- be illustrated by fastening
lustrated? together by a wire, as repre-
sented in the figure, an iron nail and a
bit of pipe-stem of equal length, and
heating them over a spirit lamp. The end of a match
having been fastened with thread to each, it is found
that the heat will travel along the nail and inflame
the match at its end long before the other match is ig-
nited.
59. PROTECTION FROM THE CENTRAL FIRE
How are we
protected from OF THE EARTH. — We are protected from the
the central heat centrai neat of the earth by the non-con-
of the earth ? *
ducting power of the rocks and soil which
form its outer crust. So a crust forms after a time over
the streams of lava which flow from volcanoes ; but,
owing to its non-conducting power, the lava below re-
mains liquid for years.
60. CONDUCTION FROM ONE BODY TO AN-
Wh en does con- mi • i • Ji
duction take °THER- — This takes place most rapidly
place most ra- the more perfect the contact between the
pidly ?
two. Conduction from air or a gas to a
32 HEAT.
solid is slow, because the gas contains comparatively
few atoms, and therefore furnishes few points of con-
tact. Between a liquid and a solid it is more rapid, be-
cause there are more. A cannon ball would grow hot
much more rapidly in boiling water than in air of the
same temperature. Between solid and solid, again, con-
duction is less rapid, because the surfaces cannot so
adapt themselves to each other, like liquid and solid, so
as to bring all their atoms together. This paragraph
refers solely to the passage of heat from the atoms of
one surface into those of the other. Th§ further con-
duction of heat depends on the substance into which
it has passed.
61. HEATING WATER. — Water is sooner
Why is water . .. .
heated sooner heated m an iron pot, or other metallic
™ianin°a vessel, than in one of porcelain, glass, or
glass vessel? earthen- ware, because the metal conducts
the heat through from the fire more rapidly. Cooling,
or the passage of heat outward when the vessel is re-
moved from the fire, goes on more rapidly in the case
of the metallic vessel for the same reason. These
statements have reference only to vessels which are not
polished. In the case of bright surfaces, another prin-
ciple is involved to be considered hereafter.
62. CLOTHING. — Fibrous substances, like
Exn am the ,
subject of do- wool, cotton, and furs are best adapted for
l clothi«g> because they are such poor con-
ductors, and beside, because they contain
air shut in between their fibres, which is a non-con-
ductor. as will be hereafter shown. The object of
clothing is not to impart heat, but to prevent its escape
CONDUCTION.
33
from the body. It -escapes more or less through all
substances, but less rapidly through the fibrous materi-
als just mentioned, and therefore their superiority for
winter clothing. If we lived in an atmosphere hotter
than our bodies, the object of clothing would be to ex-
clude heat, and the same non-conducting materials now
used would be best adapted for this purpose also.
Sometimes it is actually the object of clothing to keep
out heat ; as, when workmen enter hot furnaces in cer-
tain manufacturing processes. Thick clothing, of non-
conducting materials, is obviously best in this case also.
In summer, coarser fibre of linen, which is a better
conductor than cotton or wool, is more used, because
it conveys away the heat of the body more rapidly, as
is desirable in the warmer season.
63. FURS OF ANIMALS. — We see, in
Why has the , . , , .
Deity varied what has been stated, the reason why the
ninuffl9* Deity has clothed animals inhabiting cold
climates with fine furs. While the elephant
of the torrid zone has but a few straggling hairs, the
polar bear has a thick coat of fine fur to keep in his vi-
tal heat, and enable him to endure the extreme rigor
of a northern climate. So the sea-fowl has a thick
covering of soft down to protect him from the cold of
the ocean, while the ostrich has an open coat of scanty
feathers.
,,r, , • 64. WARMTH OF SNOW. — Snow keeps
Why does snow r
tend to keep the earth warmer in winter than it would
otherwise be, not because of any heat it
imparts, but because, by reason of its low
conducting power, and that of the air which it con-
2*
34 HEAT.
tains, it prevents the escape of the heat which is stored
in the earth from the previous summer. But for this
indirect warming effect of the snow, the cold of a sin-
gle winter would be sufficient to kill whole races of
plants. Thus, the cold of the winter weaves a garment
to protect the earth from its own influence.
How do the ^' BUILDING. — In building, the same
principles of principles apply as in the case of clothing.
Cpiyinthtcas~e Bad conductors, when suitable in other
of buildings? respects, are the best materials for walls,
making a house cooler in summer and warmer in
winter. Wood and brick, for example, are in this
respect better than iron. They keep out the heat
in summer, and, though they have the same effect
to exclude the heat of the sun's rays in winter, they
more than make up for this by preventing the escape
of the larger quantity of heat produced by the fires in-
side. The inhabitants of the Arctic regions build their
winter huts of snow, and thus make practical use of
its low conducting power. Double doors and windows
have more than a double effect in preventing the escape
of heat in winter, because of the non-conducting wall
of air between them.
,,„ . . , 66. REFRIGERATORS. — These are double-
What is the
principle in- walled wooden box-
es> «sed to
refrigerators ? articles of food from
the heat of the summer. The
space between the double walls
and top is filled with pulverized
charcoal, which has in itself very little conducting
CONDUCTION.
35
power, and again is non-conducting because of the air
between the particles.
67. FIRE-PROOF SAFES. — These are constructed on the
same principle, the space be-
tween the double walls being
filled with gypsum, or some
other non-conducting material.
They are used as repositories
of valuable papers and other
property, for greater security in
case of fire.
68. WHY BODIES FEEL COLD OR HOT. —
Why do bodies .
feel cold or A metallic door-knob feels colder than the
kot ? wood to which it is fastened, although it
cannot actually be so. It is because the metal is the
best conductor, and carries off the heat of the hand
more rapidly. If a piece of metal and wood be placed
in a hot oven till both become equally hot, as they must
by long exposure to the same heat, the metal will feel
hotter than the wood. It is because the metal, by its
greater conducting power, supplies heat more rapidly
to its own surface to be taken away by the hand.
69. SIMPLE TEST OF CONDUCTING POWER.
Give a simple
test for deter- Among bodies equally hot, the colder a
Inducting6 body feelsjthe better conductor it is. That
power of 'a body this is generally the case is evident from
the last paragraph. On applying this test, we find the
metallic lamp-stand, cooler, and therefore a better con-
ductor than the table cover on which it stands. In
an oven, or other place where the heat is greater than
that of our bodies, the test would be reversed. For
36 HEAT.
the flow of heat would be in this case into the hand,
from this highly heated object, and the body that
brought it fastest, or felt hottest, would be thereby
proved to be the best conductor.
70. LIQUIDS NON-CONDUCTORS. — Water
it in a test-tube may be boiled at the top
'quids are non- wh jje jce frozen into the bottom will re-
conditctors ? _
main unmelted. If a
bar of metal with a cavity at the
bottom for the ice were heated in
the same way, the heat would be
conducted downward so rapidly
that the ice would soon disappear.
Explain the ?!. FlRE ON WATER. — Fire may be
experiment kindled on water by pouring a little ether
with ether to /•
prove that li- upon its surface and inflaming
the flame will be found
heat. t0 have slight effect on the
temperature of the water. And, what lit-
tle effect it has, is principally due to the
fact that the glass or metal of the containing vessel
carries the heat downward and distributes it to the
liquid. When water is heated by a fire beneath it, it
is not by conduction, but by another process, explained
in a subsequent paragraph. The above experiment
may be made in a tin cup very nearly filled with water.
A tea-spoonful of ether having been poured on the water,
the bottle is to be corked and set away, for fear of ex-
plosion, from the kindling of the ether which it con-
tains. The experiment, as described, is not in the
least degree dangerous.
CONVECTION. 37
CONVECTION.
72. It has been already shown that
Explain how
liquids become liquids and gases are non-conductors.
This implies that they cannot be heated,
like a mass of metal or other solid, by communi-
cation of heat from particle to particle. Each parti-
cle, on the contrary, receives its heat directly from the
source of heat, and conveys it away, making room for
others. Hence the term convection. In the process of
boiling water, for example, the first effect of the fire is
to heat the lower layer of liquid, and thereby to expand
and make it lighter. It then rises as a cork would in
water, and gives place to another portion, which be-
comes heated and rises in. its turn. Thus a circula-
tion is commenced, the warmer portions ascending and
the cooler descending, which continues until the water
boils. Before this happens, each particle will have
made many circuits, accumulating heat with each re-
turn, but not communicating it to others. Air and
gases become heated in the same way.
73. CONVECTION MADE VISIBLE. — The
How can the ., , ,
circulation in circulation above described may be ren-
dered visible b addins a little of the " flow~
berenderedvis- erS of Slllphlir" to Water ,
iblc? . .
and then heating it in
a test-tube over a spirit lamp. The
suspended particles will be found
to move in the direction indicated
by the arrows, showing that the
water has the same motion. The
38 HEAT.
upward current is not, it is to be remembered, because
of any tendency of heat to rise. Heat, on the con-
trary, travels in one direction as well as another.
But it is, -as before explained, because hot water is
lighter than cold. Dust of bituminous c.oal answers
the purpose in this experiment still better than " flowers
of sulphur." It is necessary to have something that
will neither sink or swim, but remain suspended in
the water.
74. HEATING ROOMS. — A room becomes
How does a .
room become heated by a stove in the same manner.
heated? rpne ^T ^R imme(jiate contact with the
hot surface becomes heated and rises. Cooler air comes
in from all sides to take its place, and be heated and
less in turn. A circulation is thus established pre-
cisely similar to that which occurs in the flask, as rep-
resented in the figure. Any light object, as a feather,
or a flock of cotton-wool, held over a stove or an open
flame, will prove by its ascent the existence of the up-
ward current. How rapidly heat thus passes upward by
convection, may be proved by holding the finger above
the flame of a lamp, and then at an equal distance at its
side, and comparing the effect.
How is the at- ^' CONVECTION IN THE HEATING OF THE
mosphere heat- ATMOSPHERE. — Heat is distributed through
the earth's atmosphere in the same manner.
At the equator, where the surface is hottest, the air
heated by contact with it rises and flows off toward the
poles, while colder air from the polar regions flows in
to take its place, to be heated and rise in turn, contin-
uing the circulation. But for this arrangement, the
RADIATION. 39
equatorial regions, which are constantly receiving ex-
cess of heat from the sun, would soon become unin-
habitable by reason of its accumulation, and the polar
regions, from extreme cold. The currents or winds
thus produced are subject to great irregularities, which
are considered in works on natural philosophy.
RADIATIOK
76. The general laws of radiation
What are the °
laws of the are the same for heat as for light. Rays
™eat?i0n °f of heat divei'ge constantly from all points
of the surface of all bodies, in straight
lines and in every direction ; and the intensity of heat
varies inversely as the square of the distance. The
latter point is explained in the chapter on light.
77. HEAT is RADIATED FROM ALL BODIES.
Illustrate the . .
fact that heat It is to be observed that while light pro-
in alWradiatl~d cee(*s onlv ^roni certain bodies, heat pro-
from bodies, ceeds from all points of all bodies without
exception. If the mercury in a thermometer were fro-
zen by extreme cold, and then hung in a cavity made
for the purpose in a block of ice, radiation of heat from
the ice would melt it, even if there were no air in the
cavity to help melt it by conduction.
78. PROPORTION OF RADIATION TO TEM-
What can be
said of the pro- PERATURE. — The hotter a stove is the more
heat il Slves Ollt' This is obvious, and we
might naturally suppose that a stove twice
as hot as another stove, compared with other objects
about it, would give out heat just twice as fast. It
40 HEAT.
gives out heat,- in fact, more than twice as fast, the ra-
pidity of radiation being more than in proportion to the
temperature.
79. POLISH is UNFAVORABLE TO RADIA-
What are the .
effects of rough TioN. — A coffee-pot oi well brightened
metal will keep its contents hot much bet-.
diation? ter than a dingy, blackened one, thus re-
warding the housewife for her pains. The brightness
is not the cause of this effect. It is owing to the fact
that polished surfaces are more dense, and dense sur-
faces do not allow heat to pass readily. But if the pol-
ished coffee-pot be covered with muslin so as to give it
a less dense surface, radiation and consequent cooling
will proceed more rapidly again. One would think
that the polished surface beneath the cloth would have
the same effect in retaining the heat as before, and that
the cloth would still further retard its escape ; but ex-
periment proves that this is not the case. Radiation
depends on the surface, without regard to what is be-
neath it, and the superiority of the cloth as a radiator
is more than sufficient to make up for its non-conduct-
ing influence. Rough uncompact surfaces, generally,
radiate well. High polish being unfavorable to radia-
tion, stoves should not be too highly polished. The
high polish of soldiers' helmets makes them much
cooler than if they were made of dull metal.
,.r, . 80. COLOR DOES NOT AFFECT RADIATION.-^
What effect
has color on A black coat wastes no more of the heat
of the body by radiation than a white one.
Except in the direct rays of the sun, one is just as
warm as the other. But the former absorbs and imparts
REFLECTION. 41
to the body more of the heat which comes to it asso-
ciated with intense light, as is the case with the heat
of the sun, and therefore its advantage as an article of
winter clothing.
Tir, . . 81. TRANSMISSION OF HEAT. — The heat
What is
said of the of the sun passes with its light through
transmission ,, , -r» i /•
of heat thro' aU transparent substances. But heat from
bodies ? jess mtense sources is absorbed, and in large
part stopped by many substances which allow light to
pass : such are water, and alum, and glass to a less extent.
A glass plate held between one's face and the sun will not
protect it, but held before the fire will intercept a large
part of the heat. So a glass lens or burning-glass will
stop the heat of a fire, instead of transmitting and con-
centrating its raysj as it does those of the sun. It is a
singular fact, on the other hand, that many substances
which allow heat to pass, effectually stop the light.
Such are black glass and smoked quartz crystal. Rock
salt allows heat to pass so perfectly that it has been
called the glass of heat.
82. REFLECTION OF HEAT. — Polished
What bodies
are the best re- metallic surfaces are the best reflectors.
S53***gJ Coffee takes lonser to boil in a brisht cof-
subject. fee-pot, because the heat is reflected from
the bright surface and does not enter the liquid. If it
were desired to heat a liquid as rapidly as possible, and
keep it hot as long as possible in the same vessel, it
would be wise to take a dingy one for the rapid heat-
ing of the liquid, and then to polish it in order to fasten
the heat in. Glass mirrors do not reflect heat so well
as those of uncovered metal, because of the absorbing
42 HEAT.
power of the glass, mentioned in the last paragraph.
But this absorbing power is very slight for heat which
comes from an intense source like the sun, so that such
mirrors reflect the solar heat quite perfectly.
82. ABSORPTION OF HEAT. — Surfaces are
What bodies
absorb heat good absorbers, in proportion as they are
poor reflectors. All the heat that falls on
any surface, must be either reflected or absorbed. In
proportion, therefore, as little is reflected much is ab-
sorbed.
83. ABSORPTION CONTINUED. — Dark cloth-
What effect /•-,••, •> r
has color on ing is warmer than that of light color, for
the warmth of ^ reason tfrat heat associated with light
clothing ?
seems to follow the laws of the latter and
undergo absorption or reflection with it. Now we know
that dark objects owe their dark color to the fact that they
absorb much light, and reflect but little to the eye. Ex-
periment shows that they absorb much heat also, if the
heat be associated with light. The absorbed light must
show the way, as it were, for the entrance of the heat.
Dr. Franklin proved what has been stated, by the ob-
servation that when different colored cloths are spread
upon snow, it melts most rapidly under those which are
darkest.
84. EQUILIBRIUM OF TEMPERATURE. —
How is equili-
brium of tem- It has before been stated that heat is con-
^11™^ Stantl7 radiated from all bodies. Absorp-
tion of heat, is also universal. If any num-
ber of bodies are equally hot, they remain so, each ac-
cording to its surface, imparting to the rest and receiv-
ing from all the rest, taken together, the same quantity
RADIATION. 43
of heat. If one is hotter than the rest, it gives faster
than it receives, until the equilibrium is reached. And
if, while they are thus coming to the same temperature,
one is a good reflector, and therefore slow to receive
the heat which comes to it, it is also slow to part with
what it gets ; thus the difference of reflecting power
is without influence.
85. COOLING OF THE EARTH. — Were it
slid** of the not f°r the SU11> tne heat °f tne earth wollld
cooling of the waste away very rapidly into space. It is,
in fact, radiated into space now, as truly
as if there were no sun or stars, but these make tip for
the loss. At night, when the sun is below the horizon,
the waste by radiation takes place very rapidly, and
the earth and air grow colder in consequence. It
is not simply because of the absence of the direct
heat of the sun, for this is removed at once when the
sun sets, while the cooling proceeds until morning.
As the earth, being solid, is a better radiator than
the air, it cools most rapidly, sending out its heat
through the air into space. In this way the earth often
becomes cooled from ten to twenty degrees lower than
the air above it.
86. ICE IN THE TROPICS. — Advantage
How is ice pro- ...
duccd in the is taken of the cooling which occurs by ra-
trojncs? diation, to produce ice, in countries where
the temperature of the air does not fall to the freezing
point. Water contained in shallow vessels, placed in
trenches dug in the ground, to protect it from currents
of warm air, becomes covered with ice by a night's ex-
44 HEAT.
posure. That the water is not frozen by evaporation, is
evident from the fact that it does not freeze in windy
nights, when evaporation is greatest.
87. THE FORMATION OF DEW. — Dew
formation of does not "fall." Its deposition is an-
other consequence of the cooling of the
earth by radiation. The air, however transparent, al-
ways contains moisture, absorbed and invisible. Cold,
causes the air, like every thing else, to contract, and
presses out of it, as it were, the water which it con-
tains. Now, when at night the earth has become
cooled by radiation, the warmer air which comes in
contact with it is cooled, and thus made to deposit its
moisture in the form of dew. When the temperature
is sufficiently low, the dew takes the form of frost.
88. WHY CLOUDS PREVENT DEW. — Clouds
prevent0 ™he send back the heat radiated from the earth,
formation of -fry a new radiation, and thus prevent the
cooling which is essential to the produc-
tion of dew. No dew is found therefore, on cloudy
nights, ' when, if it came from above, like rain and
snow, we should expect most.
89. ARTIFICIAL PREVENTION OF DEW
How can the .
formation of AND FROST. — It is only necessary to sub-
stitute for clouds the artificial canopy of a
muslin handkerchief, or any other cover-
ing, at a little distance from the earth, to prevent the
deposition of dew and frost. Gardeners practised this
method of protecting their tender plants from frost,
long before philosophers explained it.
RADIATION. 45
90. ABSENCE OF DEW ON POLISHED SUR-
"Why is dew
not ' deposited FACES. — Dew does not form on polished
surfaces because they are poor radiators, or,
in other words, do not allow their heat to
escap'e, and thereby produce the degree of cold which
is required to form dew. Leaves and grass receive
most dew, because they are the best radiators.
91. SUPPOSED RADIATION OF COLD. —
Why does the .
thermometer li a piece oi ice be held before a ther-
broucht "near mometer> ^ wn"l cause the mercury to sink.
ice? It is not because cold has been radiated
from the ice, but because the thermometer, in common
with all other bodies, is constantly giving out heat,
and when the ice is near, it does not get its due portion
in return. The ice cuts off the heat that would have
come to it from other objects behind it, and gives it but
little in its place.
92. REFRACTION OF HEAT. — Rays of
How arc rays
of heat re- heat from the sun and other objects, are
refracted or bent out of their course, on
passing from one medium to
another, similarly to rays of
light. By ordinary glass
prisms most of the heat rays
are refracted in a less degree.
93. HEAT RAYS AND CHEMICAL RAYS. —
The light which proceeds from the sun, is
rays and che- accompanied by rays of heat and others
mical rays ? .
called chemical or actinic rays. In the
analysis of light by a prism, the chemical rays accu-
mulate principally in the region of the violet color of
46 HEAT.
the spectrum, while the most of the heat rays are
thrown into the region of the red, and below it. Nei-
ther the place of the heat rays nor the chemical rays
is visible to the eye, but a delicate thermometer proves
that there is most heat just below the red, and a piece
of paper covered with chloride of silver, (a substance
very sensitive to the chemical rays of light,) grows
black most rapidly in the region of the violet. The
place of the chemical and heat rays is thus shown, al-
though neither can be seen. It is not to be understood
that they are confined to the points indicated, but only
that they are accumulated there in largest proportion.
94. BURNING GLASSES. — The collection
action™ thof of raYs of heat from the sun by ordinary
burning glass- burning glasses, depends on the fact that
they are refracted, or bent out of their
course on passing from one medium to another, pre-
cisely as in the case of light. A lens made of two
watch-glasses, filled with water, answers for heat as
well as light, and may be used as a burning glass.
95. DIFFERENT HEAT RAYS. — There are
ray* of heat different kinds of heat rays, as there are of
light rays ; some will pass through one
substance best, and some through another. Thus, a
piece of smoked rock salt allows the blue heat ray of
the spectrum to pass, while alum lets the lower or
red heat ray pass.
96. ANALYSIS OF HEAT. — The analysis
How is the
analysis of ot neat is enected. by the same means as
keate/eeteJf are
through a prism just as if light were to be analyzed,
RADIATION. 47
but a dark colored glass is previously placed before the
prism, to absorb the light and allow the heat only to
pass. Emerging from the prism, it forms an invisible
spectrum of rays beyond. These rays correspond to
the different colored rays of light, and have different
capacities of passing through different substances, as
before stated. But, strictly speaking, they have no
color ; they were called blue and red, simply to de-
signate their relative position. Heat from very intense
sources is mostly violet, and violet heat passes more
readily than the other rays through most substances.
This accounts for the fact that the heat of the sun is
not stopped by glass, and many other substances
which stop the heat of a fire.
97. EFFECT OF DIFFERENT HEAT RATS
xrid of™ the IN MELTING SNOW. — Snow melts compara-
meiting of tively slowly in the heat of the sun, for
snow? J J
the reason mentioned in the last paragraph.
Being from a highly heated source, it passes through
the snow instead of stopping to melt it. But near a
fallen tree melting proceeds more rapidly, because the
heat absorbed as violet, is radiated again from the mod-
erately heated source as red heat, which, falling on the
snow in- its vicinity, is readily absorbed, instead of be-
ing transmitted.
98. BURNING GLASS OF ICE. — A lens
How can gun-
powder be iff- sufficiently powerful to ignite gunpowder
may even be made of ice. In using any
lens, it is first to be placed near the object to be ignited,
and then withdrawn till the spot of light which it
casts is round and very small. The focus to which
48 HEAT.
all the rays of light converge is thus found. The heat
focus is a little beyond, but so near that the difference
need not be taken into account.
Section 3. — Changes effected by Heat.
99. EXPANSION, MELTING, AND VAPORIZA-
TION are the principal changes effected by
heat? heat, while contraction, freezing, and con-
densation of vapor are produced by its withdrawal.
But before these changes are explained, it will be well
to consider certain remarkable differences in the heat-
ing effects of heat, in the case of different substances.
100. THE HEATING EFFECT OF HEAT IS
Are the effects DIFFERENT FOR DIFFERENT SUBSTANCES.
of neat equal
in different It might naturally be supposed that the
same quantity of heat actually imparted
to different substances would make them equally hot ;
but this is not the case. If two cannon balls of the
same size, and at the same temperature, are quenched,
the one in mercury and the other in water, the mer-
cury will be made much hotter than the water, by
the reception of the same amount of heat. It does
not simply feel hotter, as it might do if it were not
really so, from the superior conducting power of the
mercury, but it is actually so, as may be ascertained
by testing the temperature by the thermometer.
What is sped- 101- SPECIFIC HEAT. — If the above ex-
fic heat ? periment were varied, by quenching in
mercury a bullet of one-thirtieth the size of that used
SPECIFIC HEAT. 49
for the water, the two would be brought to the same
temperature. In other words, mercury requires but
one-thirtieth as much heating as water, to make it
equally hot. It fills up, as it were, with heat, more
rapidly. The comparative quantity required by each
substance is called its specific heat.
102. Taking water as the standard, and
calling its specific heat one, that of mer-
mercury? Of Cury is about one-thirtieth. That of iron
is about one-tenth. The specific heat of
other substances is given in decimals in a table con-
tained in the appendix.
What is capa- 103. CAPACITY FOR HEAT. - If We COm-
dty for heat ? pare equai {mlks of water and' mercury,
instead of equal weights, AVC make out the specific
heat of mercury to be one-half instead of one-thirtieth.
The comparison is sometimes made in this way, but
the term capacity for heat, instead of specific heat is
always employed in such cases. Thus, we say that
water has twice the capacity of mercury for heat.
,„, . . .. 104. RELATION OF HEAT AND DENSITY.
W liat relation
exists between If water were suddenly converted into
density and , , -i -i -i
capacity for niercury, much heat would be given out,
heat? as js evident from what has already been
stated. So when a metal is hammered, the capacity
of the denser metal for heat being less, the surplus
goes to make it sensibly hotter. In other words, in
proportion as density is increased in any substance, its
capacity for heat is diminished, and vice versa. It is
not, however, to be understood that the comparative
capacity for heat in different substances is always in
3
50
HEAT.
proportion to their density ; this is by no means uni-
versally the case.
105. THE OCEAN A RESERVOIR AND
How does the
ocean serve as REGULATOR OF HEAT. In hot Weather the
a reservoir -L -L >i i c ±-\ • if •
and regulator ocean absorbs the heat of the air. If it
of heat? were an ocean of mercury, it would soon
grow as hot as the air, and therefore cease absorbing •
but its capacity for heat is so much greater that this
does not occur. Again, in cold weather, it is con-
stantly giving out the large quantity it has absorbed,
but at the same time itself grows cool, though very
slowly. It is thus a reservoir of heat and a regulator
of climate.
106. FIRE BY COMPRESSION. — The fire
principle of svringe> represented in the figure, is an
the Fire Sy- instrument designed to produce fire
by the compression of air. On forcing
the piston suddenly down, the tinder below it is
ignited. This takes place on the principle already
explained. The specific heat of compressed air
is less than that of air uncompressed. When the com-
pression takes place, the surplus elevates the tempera-
ture and inflames the tinder.
EXPANSION.
107. EXPANSION UNIVERSAL. — All bodies,
ha* athea/eon solid> liquid, and gaseous, expand by heat,
dun"?* °^ b°~ and contract to tneir original dimensions on
cooling. An iron wire lengthens by heat :
the mercury in a thermometer expands and rises by
EXPANSION. 51
heating ; air partially filling a bladder expands and fills
it by the operation of the same cause.
108. HOW HEAT EXPANDS BODIES. - Heat
How does heat
operate to ex- operates to produce expansion, by insinua-
pand bodies? tmg itself between the particles of Sllb-
stances and increasing their distance from one another.
The cooling process is simply a removal of heat,
which allows the particles to assume their original dis-
tances from one another, in obedience to the attraction
of cohesion.
109. EXPANSION OF SOLIDS. — The ex-
Among solids, . . •
which expand pansion of solids by heat is comparatively
the most? smalL Among Solids, the metals expand
the most ; but an iron wire increases only ^^2 in
length on being heated from zero up to 212°. Ex-
pansion in general bulk is about three times as great
as in length. Thus, a cannon ball heated to 212°
would occupy about zj-o niore space than when cooled
down to zero.
110. ILLUSTRATION. — The expansio-n of
metals be U- "be lllustra-
lustrated ? ,
ted by ar-
ranging a brick, a knit-
tirig-needle. and a shin-
gle, as in the figure. On
heating the needle with a spirit lamp, the shingle, if
before carefully poised, will be overturned.
What appli- 11L WHEEL-TIRES, RIVETS, ETC —
cation of this Important application of even this small
expansion ts . .
made in the degree of expansion is made in the arts.
t|reg Q£ carrjage wheels, for example,
52 HEAT.
are made originally too small for the frames they are
to surround.. They are' then heated red hot and ap-
plied in a state of expansion. The contraction which
afterward takes place, on sudden cooling hy cold wa-
ter, binds the wooden frame-work together with the
greatest firmness. So in making steam-boilers, the
rivets are fastened while hot, that they may by subse-
quent contraction unite the plates more firmly.
112. HOT-WATER PIPES. — In certain
What disad- . . . ^
vantages arise uses to which iron is applied, the conse-
^ansion.6 o/*~ (luences °^ expansion have to be carefully
metals? guarded against. A cast-iron pipe for the
conveyance of steam or hot water, must not be so laid
that its ends touch two opposite walls, lest by its ex-
pansion when heated, the walls should be overturned.
113. CLAMPS IN WALLS. — If the two
ends of a Piece of metal are fixed so that
clamps in they cannot move, and contraction takes
walls ?
place by cold, the metal must break. Cast-
iron clamps in walls are frequently thus broken. If
they are of wrought iron, they often crush the stone,
and thus loosen themselves in their sockets.
114. LIFTING WALLS. — Walls of build-
Mow are walls
straightened ings in danger of falling, have been restored
b<Ld€XPcontr™- to tnen* perpendicular position by taking
tion? indirect advantage of expansion. This
is eifected, by connecting the walls to be lifted into
place, by an iron rod, fixed firmly into one wall, and
passing loosely through a hole in the other. The
whole length of the rod is then heated by lamps,
whereby expansion is occasioned, and the rod made to
EXPANSION. 53
project beyond the building. The nut with which it
is provided is then screwed up on the projecting rod,
until it touches the outside of the wall. The lamps
being then removed, the rod cools, and, by its con-
traction, draws up the walls with it.
115. FRACTURE OF GLASS VESSELS. —
fracture of Glass expands less than iron by heat, yet
glass vessels sufficiently, when expansion is unequal on
by heat? '' H
opposite surfaces, to occasion its fracture.
Thus if hot water be poured on a thick glass plate, it
cracks. The first effect is to expand the upper surface,
while the under one is but slightly affected. The ob-
vious tendency of this unequal expansion, is to warp
the plate, and curve it inward toward the under side.
But, as the glass cannot bend, it breaks.
116. HOW TO CUT GLASS BY HOT WIRE.
How can heat
be used to cut In consequence of the same unequal expan-
sion, a crack once commenced in glass may
be made to follow the heated end of a rod of iron or pipe-
stem drawn over its surface. Broken vessels of glass
may be thus cut into useful shapes. A glass vial may
be cut evenly in two, by encircling it with a ring of
iron heated to redness, and afterward plunging it into
cold water. The glass beneath the ring becomes ex-
panded through and through, and the subsequent im-
mersion in water, causes a sudden contraction in the
exterior, and consequent fracture, on the principle above
stated.
117. WOOD AND MARBLE EXPAND LIT-
TLE.^-Wood and marble expand but little
used for pen- "by heat, and are therefore sometimes used
dulum rods ? '
for pendulum rods, where careful provision
54
HEAT.
must be made against change of length by change of
weather.
118. LIQUIDS EXPAND MORE THAN SOL-
IDS.— A column of water inclosed in a glass
sion of water tube, will expand aV in length on being
heated from freezing to the boiling point
of water, while a column of iron will expand only ^l^.
119. ILLUSTRATION. — The overflow of
Illustrate the
expansion of water from full vessels before boiling
liquids by heat. commenceSj so often observed in the
kitchen, is in consequence of expansion by heat. To
illustrate the expansion of liquids, a
test-tube full of water may be heated
over a spirit lamp, as indicated in the
figure. The water will be found to
heap itself into a convex surface over
the mouth of the tube, and even to run
over, long before boiling commences.
120. COLD WATER EX-
What effect
PANDS BY COLD. - There is
an important exception to the general law
of expansion of liquids by heat and contraction by cold,
or withdrawal of heat. Very cold water (39 F. ) expands
by further cold before it freezes. Again, on conver-
sion into ice, it undergoes still further expansion.
12 1 . ILLUSTRATION. — Expansio n by these
How may ex-
pansionbycoid combined causes may be shown by bury-
be illustrated? ing ft tegt.tube full of water m a mixtllre of
snow and salt. Before the water is completely frozen,
it will rise at least a quarter of an inch, and fill the
tube..
has cold on
'
EXPANSION. 55
The greaterpart of this expansion is owing to
the latter of the causes above mentioned. The
freezing mixture employed is made of two
parts snow to one part salt, brought into
the cup alternately, in small portions. It
is well to wrap the cup in flannel, or other
cloth, to prevent loss of heat. From ten to fifteen
minutes are required for the experiment. If the water
is perfectly frozen, the tube will be cracked by its ex-
pansion.
122. COLD WATER FLOATS ON WARMER
coldwaterfoat WATER AN» PROTECTS IT.— It Was shown
on warmer wa- in the last paragraph that very cold water
(below 39°) is in an expanded condition,
and occupies more space than warmer water. It fol-
lows that it is lighter, arid will float on warmer water.
As the weather grows colder each winter, and the time
approaches for the formation of ice, in rivers and lakes
the cold water does actually float on the warmer, on a
grand scale, and protect it from the cold. The body
of water being thus protected, ice never forms many
feet thick. The case would be very different if water
grew constantly heavier by cold. The surface water
would then constantly sink, until all were reduced to
the freezing point. Cooling does, in fact, proceed in
this way until the temperature sinks to 39° ; then the
exception comes in play, and the surface water, as
before stated, retains its place and exerts its protecting
influence. When ice is subsequently formed it has the
same effect.
56 HEAT.
123. CONSEQUENCES OF THE LIGHTNESS
WJtat conse- r> ,,
qucnces remit OF VERY COLD WATER. But lOI the 16-
from the ex- markable fact that more cold makes very
pansion of wa-
ter by cold ? cold water lighter, and not heavier, and
thus enables it to exert the protecting influence just
explained, the cold of a single winter would be suffi-
cient to kill all the fishes inhabiting our lakes and
rivers. Another consequence would be change of cli-
mate, as a necessary result of the formation of im-
mense masses of ice, which the heat of the summer
would be insufficient to melt. The temperate regions
of the earth would thus become uninhabitable. Such
are the consequences which are obviated by this
remarkable exception to a general law of expansion.
The whole realm of nature furnishes no more remark-
able evidence of design on the part of the CREATOR.
124. SOME LIQUIDS EXPAND MORE THAN
In what pro-
portion do spi- OTHERS. — Some liquids expand more by
Toil,ald water heat than others. Spirits of wine, on be-
expand? jng heated from 32° to 212°, increases one-
ninth in bulk ; oil expands about one-twelfth, and wa-
ter, as has before been stated, one-twenty-third. It is
much to the advantage of the dealer in spirits to buy
in winter and sell in summer. Twenty gallons
bought in January, will have become, by expansion,
twenty-one in July. The difference between the cold-
est and warmest weather of the year, is sufficient to
make about this difference in bulk.
How do gases 125' GASES EXPAND M°RE THAN EITHER
compare with SOLIDS OR LIQUIDS. — Gases expand more
solids and li- , . ,
quids in ex. tnan either solids or liquids by heat. The
t reason is, that in gases there is no co-
EXPANSION. 57
hesion to overcome, as in the two other states of
matter. While iron increases in general bulk ^y^th.
and water about ^Vd, on being heated from the freez-
ing to the boiling point of the latter, air expands more
than Jd by the same increase of temperature.
126. LAW OF EXPANSION FOR GASES.
State the law
of expansion Gases expand ^oth of the bulk which they
for gases. possess at 32°, for every degree above that
point, and contract in the same proportion for every de-
gree below it. Thus, 490 cubic inches at 32° would
so expand as to occupy an inch more space at 3-3°,
still another inch at 34°, and at the same rate for
higher temperatures. And the same quantity would
contract by cold, or withdrawal of heat, so as to oo
cupy an inch less space at 31°, and two inches less at
30°, and so on for lower temperatures. The law is
the same for steam and other vapors.
What is a 127. THE THERMOMETER. — The ther-
thermometer ? niometer is an instrument in which ex-
pansion is made use of to show changes of tem-
perature. A straight wire, which would grow regu-
larly and perceptibly longer in proportion to the
increase of temperature, would form the most conve-
nient thermometer. But solids do not expand enough,
or with sufficient regularity, for this purpose. The
liquid metal mercury, is therefore employed instead,
being inclosed in a glass tube and bulb.
128. MANUFACTURE OF THERMOME-
How are ther-
mometcrsman- TERs. — In making thermometers, the
mercury being first introduced into the
bulb, is boiled, so as to expel all air and moisture,
3*
58 HEAT.
and fill the tube with its own vapor. As the metal
cools, it contracts and collects in the "bulb and lower
part of the tube, leaving a vacuum above. The
end of the tube being then closed by fusion, the
instrument is complete, with the exception of grad-
uation. Used in this condition, the mercury would
be observed to rise and fall with changes of tempe-
perature, but we should not be able to say how much
or how little.
129. GRADUATION OF THERMOMETERS. —
thermometers To obtain a fixed point from which to
graduated/ count, the instrument is immersed in melt-
ing ice, and the point to which the mercury sinks
scratched on the glass. This point is called zero.
Another fixed point is obtained by immersing the
thermometer in boiling water, and when the
mercury has risen, noting this height also on
the glass, and marking it 100°. The space be-
tween the two points is next divided into one
hundred equal parts, by scratches on the glass,
and numbered from one up to a hundred. The
upper and lower portions of the tube are marked
off into divisions of the same length, for very
high and low temperatures.
CENTIGRADE THERMOMETER.
Describe the
Centigrade A thermometer graduated as above
is called a centigrade thermometer,
from th e fact that the space between < ' boiling ' ' and ^
" freezing" is divided into one hundred degrees. This
is by far the most rational method of graduating,
and these thermometers are in general use on the
THE THERMOMETER.
59
continent of Europe, and by scientific men all over
the world.
131. FAHRENHEIT THERMOMETER. — This
Describe the .
Fahrenheit is the thermometer in common use in this
thermometer. country. The iristrument itself is pre-
cisely the same as the centigrade. The difference is
only in the graduation. In graduating it, the space
between the freezing and boiling points having been
marked on the glass, is divided into one hundred and
eighty parts, and the rest of the tube, above and below,
into similar spaces. The zero, or starting point, is
fixed lower down than in the centigrade,
where nothing especial happens, instead of
where water freezes. The consequence is,
that in counting up and affixing the numbers?
the freezing point comes at 32°, and the
boiling point at 212°. There is no good rea-
son for placing the zero there, or for qhoosing
such a number as 180 for the number of de-
grees between freezing and boiling. The
centigrade graduation is, therefore, much to
be preferred. If a thermometer of each
kind were immersed in boiling water, the
mercury would rise in the centigrade to the
point marked 100, and in the Fahrenheit *^ ^^
to the point marked 212. In the same way,^ero cen-
tigrade corresponds to 32° Fahrenheit. The two ther-
mometers are compared in the figure.
ff oio is extreme 132. EXTREME COLD, HOW MEASURED.
coidmeasurcd? AS the temperature is lowered, the mer-
cury of the Fahrenheit thermometer sinks, until by
60 HEAT.
sufficient cold it reaches 39 degrees below zero.
There, intense cold has no effect upon it, for at this
point the mercury freezes. How much colder it is
than 39° cannot be told, therefore, by the mercurial
thermometer. Thermometers containing alcohol in-
stead of mercury are used for this purpose, because al-
cohol never freezes, and will continue to sink further
and further in the tube the colder it grows.
133. EXTREME HEAT, HOW MEASURED.
How is extreme
heat meas- If a Fahrenheit thermometer is heated,
the mercury in it rises, till it reaches 662°,
and then begins to boil. A little more heat forms suf-
ficient vapor of mercury to burst the tube. For this
reason, a mercurial thermometer cannot be used to
measure extreme heat. A platinum bar inclosed in a
black lead tube shut at the bottom, is common-
ly employed for this purpose. Tube and bar are
placed on the fire, or in the melted metal, whose
heat it is desired to measure, one end being left
out, so that it can be seen. The consequence is
that the platinum bar expands, and projects
from the earthen tube. The tube itself expands but
little. The further the bar projects, the greater is the
heat. As it pushes out, it is made to move an index
hand, and point to the number indicating the tempera-
ture, on a graduated arc. This arc is first graduated by
repeated trials, observing how much the bar projects
and moves the hand by the same heat which raises
the mercury one degree in the Fahrenheit thermometer.
n ., ., 134. THE AIR THERMOMETER. — A col-
Describe the ,
air thermome.- umn of air confined in a glass tube over
***' colored water, was the first thermometer
LIQUEFACTION. 61
used. Heat expands the air and lengthens the column
downward, pushing the water before it, while cold has
the contrary effect. The temperature is thus indicated
by the height at which the water stands.
135. ILLUSTRATION. — The principle of
^incTll *o/ the air thermometer may be illustrated as
the air ther- represented in the figure. A
mometer. ^ , . , ,,, -.„ , ,
test-tube is half filled, and
then inverted in a glass of water without
allowing the water which it contains to
flow out. Heat applied to the tube will lengthen the
column of air by expansion.
LIQUEFACTION.
136. SOLIDS BECOME LIQUIDS BY HEAT.
flow do sohds
become li- m On being heated up to a certain point, solids
quids? are jilted, or converted into liquids.
Thus, at all temperatures below 32°, water is solid
ice, but the moment it is warmed up to this point,
by change of weather or other means, it begins to
melt. The temperature at which this change occurs
is called the melting point. 32° is therefore the melt-
ing point of ice. The melting point of sulphur is
226°, and of lead, 612°.
137. ALL SUBSTANCES ARE FUSIBLE. —
Are all sub-
stances fusi- All substances are fusible, or, in other
words, may be melted ; but the melting
point of all is not definitely known. Thus carbon has
been fused by the heat of the galvanic battery, but it
is impossible to state the melting point in degrees.
62 HEAT.
Under great pressure, increased heat is required to ef-
fect fusion. Thus the melting point of sulphur is
raised from 226° to 285°, by a pressure of 11,880 Ibs.
to the square inch.
nrj . 138. DISAPPEARANCE OF HEAT IN MELT-
Wtiat remark-
able drcum- TNG. — Melting or fusing is effected by heat,
stance attends
the melting of and a remarkable circumstance attending
it, is the disappearance of the heat which
has effected the change. Thus, if a thermometer be
applied to ice or snow which has just begun to melt,
it will be found to stand at 32°. Let the ice be then
introduced into a tumbler, and placed on a stove, and
the temperature again tested at the moment when the
conversion into water is completed. The thermometer
will be found again to stand at 32°. The water produced
is no hotter than the original ice, yet heat has been pour-
ing into it, through the bottom of the ves-
sel,during the whole process of melting.
If a piece of glass of the same size had
been subjected to the same heat, it would
have grown constantly hotter. It fol-
lows that in the case of the ice there
has been a disappearance of heat. This
disappearance always occurs whenever
a solid is converted into a liquid.
What other ^9. ANALOGOUS DISAPPEARANCE OF
{£appTarance ACIDITY-— Chemistry furnishes other in-
does chemistry stances of disappearance, which may help
us in understanding this one. If vinegar
be poured upon chalk it loses its sourness. It is be-
cause a combination has taken place between the acid
FREEZING POINT. 63
vinegar and the lime which the chalk contains, and a
new substance, called a salt, has been formed out of
both. So in the present case, we may suppose that
heat and the solid have combined to form a liquid, and
the property of heat to effect the senses and the ther-
mometer, has at the same time disappeared. Any liquid
may therefore be regarded as a compound of solid and
heat. The heat which thus disappears is called com-
bined, or latent heat.
Mention some 140. FREEZING MIXTURES. - When Solids
feezing mix- take a liquid form by other means, as. for
tures. How do ** ;.
they produce example, when salt dissolves in water, the
temperature is generally much reduced.
Nitre, for example, reduces the temperature of water in
which it is dissolved from 15 to 18 degrees, and is there-
fore much used in the East, where it is abundant, for
cooling wines. Mixed nitre and sal-ammoniac have a
still greater effect. Sulphate of soda drenched with
strong muriatic acid, will reduce the temperature from
50° to zero.
141. When two solids, on being mixed,
Mention other . .
freezing mix- become both liquid, still greater cold is
often roduced- Tnis is the case witn a
duce greater mixture of snow with common salt, or with
chloride of calcium. By the former mix-
ture, used as shown in paragraph 121, ice cream is
frozen. By the latter mixture, a cold sufficient to freeze
mercury may readily be produced. For this purpose,
three parts of the salt are to be mixed with two of dry
snow.
64 HEAT.
142. THE MELTING OF SNOW COOLS THE
How docs the — Whenever ice is converted into wa-
inelting of
snoiv affect the ter, whether rapidly by fire or slowly
by change of weather, the disappearance
of heat, above mentioned, occurs. Thus, when the
snow melts in spring, heat is drawn off from the air
and made latent, or combined in the water which re-
sults from the melting. This makes the weather
cooler than it would otherwise be, and retards in a
measure the advance of spring.
How do liquids 143. FREEZING. — Liquids become solids
become solids? ^y t}ie removal of their combined heat.
Thus, if molten lead be allowed to stand awhile, the
heat which it contains passes away into other objects,
warming them ; and the metal itself, having lost its
heat, becomes solid. So in winter, the combined heat
which is contained in water, is conveyed away by the
colder air, and the water, having lost its heat, is con-
verted into ice.
144. FREEZING POINT. — The tempera-
What is the L
freezing point ture at which a substance passes from the
of a liquid? liquid into the golid gtate ig called the
freezing point. Thus, 32° is the freezing point of wa-
ter. The freezing point of any substance is, as might
be supposed, the same as the melting point. Water, for
example, becomes ice in process of cooling, at the
same temperature that ice becomes water in process of
heating.
145. ALL LIQUIDS HAVE THEIR FREEZ-
Can .all liquids
be frozen? ING POINTS. — There is good reason to be-
Give examples. ^Q ^ ^ ^.^ without exception>
L AT E NT U R AT. 65
have their freezing points, but the reduction of tem-
perature requisite has not in the case of all been at-
tained. Alcohol and ether, for example, have never
been frozen.
146. IN FREEZING, LATENT HEAT BE-
whatfrbecomes COMES SENSIBLE HEAT.— If Water, in Sllffi-
of the latent cient quantity, be taken into an apartment
whose temperature is several degrees be-
low the freezing point, and then allowed to become
ice, it will be found that the freezing process has ac-
tually warmed the apartment several degrees. The
latent heat has been drawn off by the colder air of
the room, raising its own temperature, and leaving the
water in the condition of ice.
147. CELLARS WARMED BY ICE. — In ac-
How can cel-
lars be warmed cordance with the principle above stated,
tubs of water are sometimes set to freeze
in cellars, thereby to prevent excessive cold. And
even in the coldest climates a sufficient supply of wa-
ter might thus be made to secure an apartment against
extreme cold.
148. EFFECT ON CLIMATE. — The milder
ha%afhe free*- climate of the vicinity of lakes which are
ing of water accustomed to freeze in winter, and the
on climate ? ~ . , .
moderation of the weather during a snow
storm, are accounted for on the same principle. As the
melting of snow retards in a certain degree the ad-
vance of spring by the heat it abstracts from the at-
mosphere, so the formation of ice tends to make the
advance of winter less rapid, by the heat which it
evolves.
66 HEAT.
CHAPTER VII.
VAPORIZATION.
149. FORMATION OF VAPORS. — While
Do vapors . .
form at all melting, or the conversion of a solid into
temperatures? a liquid) occurs only when the solid is
heated up to a certain fixed point, the conversion of a
liquid into a vapor takes place at all temperatures.
Thus water is always passing off into vapor from the
surface of the ocean, and from the moist earth.
150. VAPORS TRANSPARENT. — All vapors
What is the
appearance of are perfectly transparent, like the atmo-
sphere. If water be boiled in a flask, it
will be found that the steam within the flask is as
transparent as air. The steam thrown from a locomo-
tive would be invisible if it remained steam We
should hear its roar, but see nothing.
151. DENSITY OF VAPORS. — Vapors are
/« the density
of vapors uni- of all degrees of density. The vapor of
water may be as thin as air, or, again, al-
most as dense as water itself.
152. ELASTICITY OF VAPORS. — All va-
lllustrate the
elasticity of pors are elastic, like air. Steam, like air,
vapors. ft compressed in a cylinder, with a close
fitting piston, by a heavy weight, would expand again,
and force the piston out, as soon as the weight were
removed. The force with which a vapor expands, or
strives to expand supposing the weight not removed,
is called its elastic force or tension.
VAPOR. 67
153. DENSITY DEPENDS ON TEMPERA-
How does tern-
perature a/ect TURE. — If water is boiled in a flask, the
density? latter Decomes filled with steam> But?
although full, more steam can be crowded into the
same space. On corking the flask and continuing the
heat, the temperature of the water will be raised.
Then, forced as it were, by the additional heat, its par-
ticles have the power of crowding into the steam be-
fore produced, and making it more dense. But after
a time, no more can be forced in until the temperature
is still further increased. In other words, there is a
maximum density corresponding to every temperature.
And what is here said of steam, is true of vapor of
water produced at lower temperature, and also of other
vapors. The higher the temperature, the greater is
the density of all vapors, provided a surplus of material
is present. But if this is not the case, heat has
simply the effect of expanding the vapor as it would
an equal quantity of air. In the case of a partial
supply of water, the vapor grows more dense, but
does not reach the highest density which it would
have at the same temperature with a full supply.
TI™ , , 154. DISAPPEARANCE OF HEAT IN VA-
What remark-
able drcum- TORS. — The same disappearance of heat
stance attends , . . 1-1- j
the formation which occurs when a solid is converted
oj- vapors? ^Q a jjquj^ occurs also when a liquid is
converted into a vapor or gas. Thus, if we wish to
cool a room in summer, we sprinkle the floor. As the
water evaporates, much of the heat of the room dis-
appears. It has entered into combination with water
to produce vapor, and has no longer the power of af-
68 HEAT.
fecting the senses and the thermometer. In the same
manner, our bodies are cooled in summer by perspira-
tion, and the evaporation which accompanies it. All
vapors may, indeed, be regarded as combinations of
heat with the liquids from which they are formed.
And in this case, also, the heat which becomes latent
in thus combining, is called latent heat.
155. FREEZING BY EVAPORATION. — The
How can ether
be made to more rapidly a substance evaporates, the
^Explain* ^its niore heat does it require for the evapora-
action. tioii. This it obtains from objects in con-
tact with it. Ether may be made to evaporate so
rapidly as to freeze water, even in summer. This is
best accomplished by covering the bottom of a test-
tube with a cotton rag, or several layers of porous f p
paper, as represented in the figure, dipping it into
ether, and then waving it to and fro in the
air, or spinning it between the palms of the hands.
By repeating this process several times, a few
drops of water, previously placed in the tube, may
be frozen. A mixture of liquefied carbonic acid and
nitrous oxide gases, previously liquefied, produce on
evaporation a temperature of 220 degrees below zero.
156. PROTECTION FROM HEAT BY EVA-
How does eva-
poration pro- PORATION. — By previously moistening the
tect from heat? fingerS; they m&y bu dipped unharmedj for
an instant, into molten lead, or passed through a stream
of white-hot iron as it flows from the furnace. A
cloak of comparatively cool vapor is formed from the
moisture upon the fingers, and keeps them from con-
tact with the molten metal.
VAPOR. 69
pp>
157. RELATIONS OF AIR AND VAPOR. —
•Does vapor rp^Q earth is surrounded by air to the
displace air ?
depth of fifty miles. It is also surrounded
by vapor occupying the same space which the air oc-
cupies. But they are independent of each other.
Each contracts for itself, and expands for itself, accord-
ing to the temperature. When more vapor is produced
by evaporation from the sea, or other sources, it rises
into the air without displacing it or pushing it aside,
only rendering the vapor which it before contained
more dense.
158. QUANTITY OF VAPOR IN THE AT-
^ vapor M°SPHERE- — The air is always full of va-
in the por ; that is, where there is a cubic inch
of air, there is a cubic inch of vapor with
it, occupying the same space.
Upon what 159' QUANTITY OF WATER THE AIR MAY
does the quan- CONTAIN AS VAPOR. — The quantity of wa-
tity of water . , * . .
in the air de- ter present in the air, in the form of trans-
Pend? parent vapor, depends on the density of the
vapor, and this differs, as has been shown, according to
heat and the abundance of water. In summer, and
over the sea, it is commonly most dense. At a me-
dium summer temperature of 75 degrees, the vapor in
the air is sometimes so dense that every cubic yard of
air contains a cubic inch of water, in this form. But
it can never at this temperature contain more. It is
then said to be " saturated," and also that its capacity
for water is filled.
70 HEAT.
CAPACITY OF THE AIR FOR WA-
What effect
has heat upon TER INCREASED BY HEAT. - But, as the
the quantity of
vapor present weather grows warmer, the capacity of
the air for moisture is increased, so that at
100°, it can contain twice as much as at 75°, or
two cubic inches. On the other hand, as the weather
grows cooler, its capacity is diminished, so that at 50°
it can hold scarcely more than half a cubic inch, and is
saturated by this comparatively small quantity. And,
in general, the capacity of the air for moisture is in-
creased by the elevation of its temperature.
161. EFFECT OF WIND. — Wind causes
evaporation to proceed more rapidly, not
tity of vapor because the air in motion has any greater
in the air ? r . , •.
capacity for moisture, but because new
portions of air are brought successively into contact
with the wet surface. As fast as one portion has im-
bibed a certain amount of moisture, another portion of
drier and more thirsty air takes its place.
162. DEPOSITION OF MOISTURE. — It fol-
Explain the
deposition of lows that air that is saturated, or, in other
words, has its full portion of moisture in
the form of vapor, must deposit a portion of it in the
form of water in cooling. Thus a cubic yard of sat-
urated air at 75°, on being cooled down to 50°, would
yield half a cubic inch of water, or half of the whole
quantity which it originally contained. If we sup-
pose the experiment to be performed in a glass vessel
where the eifect of cooling could be observed, we
should first see a mist or dew within the box, consist-
ing of the particles of water which the colder air can
VAPOR. 71
no longer retain. This mist would gradually deposit
and collect in the form of water, and if measured,
would be found to make more than half a cubic inch.
Something less than half a cubic inch would remain
as invisible vapor in the cooled air. If the air were
cooled further, part of this would be condensed to
water.
What is 163. UNSATURATED AIR. — Air that does
said of unsat- not contain its complement of water will
urated air and
its moisture ? not yield any by slight cooling. It would
be like slightly compressing a half-filled sponge. But
as the cooling proceeds, the vapor becomes so dense
that further cooling will cause a deposition of moisture.
A cubic yard of air at 75°, containing only half a cubic
inch of water in the form of vapor, would yield none
on being cooled down to 50°. At this point the formation
would commence. If it contained originally less than
half a cubic inch, it would have to be cooled still lower
before any moisture made its appearance. The less
the moisture, in short, the more cold it would require
to wring it out.
Is the quantity 164. QUANTITY OF VAPOR IN THE AT-
MOSPHERE— As has been already stated,
ways propor- the capacity of air for vapor is in propor-
tioned to its . m,r . -
warmth? tion to its warmth. The air of summer
can therefore contain more than that of winter ; and
it frequently does so. But this is not necessarily the
case, for the capacity for moisture is not always filled.
Hot air over a desert, for example, contains less mois-
ture than cold air over the sea. And in the same lo-
cality, and during the same season, the quantity of
72 HEAT.
moisture in the air will differ from day to day, and
from hour to hour. This will depend a good deal on
the wind, whether it blows from the land or from the
sea. Sometimes it contains a cubic inch of water in
the form of vapor in every square yard, but generally
less.
165. MIST AND FOG. — These are
What is the 1 .
cause of mists aqueous vapor, rendered visible by the
and fogs? cooling of the air, as before explained.
When the air is saturated, the least cooling will pro-
duce a fog, as in the case supposed in paragraph 129.
When it is not saturated, more cooling will be required,
as in the case supposed in the subsequent paragraph.
The beautiful veil of mist, which forms in summer
nights over low places, is owing to the cooling of the
air below its point of saturation, which takes place
after sunset.
166. MIXED CURRENTS OF AIR. — The
££*»" phenomena of mist> f°g' clouds> and con-
fogs by mixed sequently of rain, are more commonly
currents of air . . . ., , , ,
owing to the mixture of cold and warm
winds or currents of air. When this admixture takes
place, the warm air becomes colder, and tends to de-
posit its moisture, and the cold air warmer ; and it
might be at first supposed that those two influences
would counteract each other. For example, if a cubic
yard of air at 100° mixes with a cubic yard at 50°, they
both become 75°, and it might be thought, that the
warming of the colder cubic yard would increase its
capacity for moisture, as much as the cooling of the
warmer cubic yard would diminish its capacity, and
FOG. 73
that consequently no mist would be produced. But,
as before stated, it has been ascertained by experiment
that hot air at 100° will contain about two cubic inches,
and air at 50°, about half a cubic inch of water. The
two would therefore contain two and a half cubic
inches. But air at 75° can hold but one cubic inch,
and consequently the two cubic yards would hold but
two cubic inches. The surplus half inch would con-
sequently take the form of visible moisture, called
cloud, fog, or mist, according to circumstances. It is
not to be understood, from what is above stated, that
half a cubic inch of water is always yielded by every
two cubic yards of air at 50° and 100° which come to-
gether ; if they are not totally saturated, the quantity
will be less.
167. FOGS ON THE SEA COAST. — The
Why are fogs
produced on sea is cooler than the land in summer, and
the sea coast? warmer m winter. As a consequence, the
air above the sea is cooler in summer and warmer in
winter, than that above the land. The admixture of
these bodies of air, which takes place along the coast,
produces fogs on the principle above stated.
168. FOGS ON RTVERS. — When land and
Why do fogs
form on riv- water have the same temperature, as may
be the case with small lakes and rivers,
the difference of radiation during a single night often
produces fogs. The land cools more rapidly than the
water. As a consequence, the air above the land is
cooler than that above the water. As the two bodies
of air mingle, fog is produced, and is seen following
4
74 HEAT.
the devious course of the river, or brooding over the
lake in the morning.
169. NEWFOUNDLAND FOGS. — The fogs
What causes __ ,, ,
the Newfound- on the banks of Newfoundland are owing
land fogs? ^Q ^ mixture of cold winds from the
north, with the warm air of the gulf stream, which
passes along that part of the ocean.
170. CLOUD-CAPPED MOUNTAINS. — The
402? °ro- temperature of the air at high elevations
duced on high is always lower than at the general level
mountains?
of the earth. As the warm breeze comes
up from the warmer valleys, the two currents min-
gling, produce clouds. A clear atmosphere through-
out a whole day is rare, on high mountains.
171. DEW POINT. — It has been already
What is the geen ^^ ajr ^as to be cooled more or less
dew point ?
before it yields moisture, according to the
amount which it contains. If it contains about one
cubic inch to the cubic yard, or, in other words, is satu-
rated, the least cooling will cause the appearance of
visible moisture. If it contains half as much, it must
be cooled down to 50° P. If it contains less than half
as much, still more refrigeration is required. The
temperature at which the deposition be-
gins in any case is called the dew point.
172. HOW TO FIND THE
How can the
dew point be DEW POINT. - It is Common-
ly found by adding ice, lit-
tle by little, to a glass of water con-
taining a thermometer. As the water
grows cool, the glass cools also, and as a
DEW. 75
consequence, the exterior air immediately in contact
with it. After a time, moisture begins to deposit. The
temperature at which this occurs is noted, and is the
dew point.
173. DEW. — The earth cools, as has
Explain the .
formation of been before stated, every clear night, by
radiation. The air in immediate contact
with it, becomes thereby so much cooler, that it cannot
retain all its water in the form of invisible vapor, and
the deposition of the surplus in the form of dew is the
consequence.
174. Grass and foliage receive most dew
because they are good radiators, and losing
the most their own heat most rapidly, cool down
the air sufficiently to cause a deposition of
its moisture. The soil itself, and stones, receive less,
or none at all, because they do not, by their own ra-
diation, become sufficiently cool to produce the same
effect. Dew does not form on a cloudy night, because
the clouds radiate heat to the earth and thus prevent
the requisite cooling.
175. CAPACITY FOR VAPOR : EXPANSION
How is it -r. . -, -i
known thatthe NOT THE CAUSE. It must not be Supposed
increased ca- that the increased capacity of air for va-
pacity of air .
for moisture por, which results from heating, is owing
*° to its exPansion. Air does indeed expand
about one-twentieth between 50° and 100°,
but its capacity for moisture is quadrupled by the same
rise of temperature.
76 HEAT.
176. ABSORPTION NOT THE CAUSE. — It
MM* allorp- is not uncommonly supposed that the air
tion is not, the acts to absorb vapor as a sponge does to
draw up water. The term " saturated"
used for convenience in scientific works is calculated
to give this impression. But vapor rises just as well,
and even more rapidly, into a vacuum, or space from
which all the air has been removed.
WJiat then is 177. INCREASED DENSITY OF VAPOR THE
the cause? CAUSE. — The air absorbs any vapor that
may be formed, whether more or less dense. At higher
temperatures, denser vapor is produced. It follows that
the air will contain more water, in proportion to the
elevation of its temperature.
178. REMOVAL OF AIR DOES NOT IN-
Does the remo- .
val of air in- CREASE THE QUANTITY. It might be SUD-
"formation *o/ Pose(^ tnat more water would rise into a
vapor ? vacuum in the form of vapor, than into a
space filled with air, on the ground that the removal
of the air would make more room for something else.
But this is not the fact. The presence or absence of
air makes no difference.
179. SEVERAL GASES AND VAPORS MAY
Do vapors and _ ., 1 , ,,
gases exclude OCCUPY THE SAME SPACE. It follows from
each other ? the lagt paragraph that vapors do not dis-
place the air ; they penetrate it instead. And it is a
remarkable fact, that a number of vapors may occupy
the same space without interfering with one another ;
and each in the same quantity as if the rest were ab-
sent.
VAPOR. 77
Give the exam- 180. Thus, as much water will rise in
Ples- vapor into a jar of air as if it were a va-
cuum. And, in addition to this, as much alcohol and
ether successively, as if the jar were entirely empty.
The tension or pressure from within, outward, is, of
course, increased by each additional vapor.
181. MOIST AIR LIGHTER THAN DRY.
Why is moist
air lighter It would naturally be supposed that air
than dry air ? contajnjng moisture, would be heavier than
air containing none. And it would be so, but for the
fact that the presence of vapor causes the air to ex-
pand slightly, and grow lighter, and this to an extent
more than sufficient to compensate for the increase of
weight.
BOILING.
182. WEIGHT OF THE ATMOSPHERE. —
lt As an introduction to the subject of boil-
atmosphere ing^ jt will be necessary to consider the
has weight ? -
pressure of the atmosphere. The earth is
surrounded by an atmosphere, estimated to be fifty miles
high. It is very light compared with the earth itself, or
with water. But it has weight, as may be proved by
weighing a bottle full of air, and then pumping out
the air and weighing it again. The empty bottle will
be found to weigh less than the bottle full of air.
183. ANOTHER PROOF OF THE WEIGHT
Give another
proof that air OF THE AIR. — That the air has weight, is
has weight. again proved by tying a piece of bladder
78 HEAT.
over a glass cylinder, open at both ends, placing the
open end air-tight on the plate of an air pump, and
then exhausting the air. The pressure of the column
of air that stands on the bladder is sufficient to break
it, and the air settles in, as effectually as if it were a col-
umn of iron. The atmosphere exerts such pressure,
amounting to about fifteen pounds to every square inch,
on all parts of the surface of the earth.
184. A SIMPLE MEANS OF PROOF. -
Describe a
simple means Wind a stick with cotton and press
°that°airl * has it; to the bottom of a test-tube, con-
wight. taining enough water thoroughly to
moisten it. It will be found difficult to withdraw
the piston. The difficulty arises from the fact that
the column of air which rests upon it, must be
lifted at the same time. Having raised it a little way
and released it, the piston flies with force to the bot-
tom, owing to the weight of the same column of air.
185. ELASTIC FORCE OF THE ATMOSPHERE.
Every cubic inch of air at the surface of
its elastic the earth, may be likened to a piece of in-
dia-rubber, which has been compressed into
the space of a cubic inch, by a heavy weight placed on
it. If we suppose a piece of rubber, while thus com-
pressed, to be confined in a strong metallic box, it would
evidently exert an elastic force in all directions, equal
to the force which compressed it. So the lower por-
tions of air, which are kept compressed by the air
above, exert elastic force. And it is better to regard
the pressure of fifteen pounds on every square inch of
PRESSURE OF THE ATMOSPHERE. 79
the surface of the earth, as a consequence of the elastic
force of the lower portions of air, rather than the direct
effect of the weight of the whole air. The weight of
the whole atmosphere produces the elastic force of the
lower portions by compressing them, and the elastic
force of the lower portions exerts the pressure.
Why are we 186. WHY THE PRESSURE OF THE AIR
notcrushedby DOES NOT CRUSH US. If a thin glaSS V6S-
the pressure of '- . -, -, -, . ,
the atmo- sel were turned upside down, and air-tight,
sphere? upon a table, it would collapse but for the
fact that it is filled with air, which, according to the last
paragraph, has elastic force equal to that of the air
without. So our bodies would collapse, but for the fact
that our lungs, and all of the cavities of the body, are
filled with air, possessing the same elastic force as the
external air ; a force which it had acquired by compres-
sion, before it was taken into our bodies.
187. QUANTITY OF WATER THE PRES-
What sustains
the water in SURE OF THE AIR WILL SUSTAIN. If a
^uM^rfre- tumD^er be filled under water, and then
sentcd in the lifted OUt bottom Up-
figure ? 1
ward, as shown in the
figure, it is well known that the wa-
ter will not run out. The pressure
of the atmosphere on the surface of
the water outside, keeps the water forced up on the in-
side.
188. The effect would be the same if
What quanti- ,
tu of water the tumbler were twice as tall, or if we
• * i *^ . i
suppose it lengthened into a tube thirty-
three feet long. If a still longer tube
80 HEAT.
were used, it would be found that the level
of the water inside, would never be more than
thirty- three feet above the level outside. The
remainder of the tube wonld be empty, as re-
presented in the figure. In other words, the
pressure of the atmosphere will sustain a col-
umn of water thirty-three feet high. Water
rises in a pump from this cause.
189. QUANTITY OF MERCURY THE
incheTofnier- PRESSURE OF THE AIR CAN SUSTAIN.
cury will the in performing the experiment of
air sustain?
the last paragraph with mercury, it
will be found that the level within the tube, will
be thirty inches above the external level. In other
words, the pressure of the atmosphere will sustain a
column of mercury thirty inches high.
190. If a long tube is used, there is, of
Explain the __ . .
Toricdlian course, an empty space above. This is
vacuum. caiied the Toricellian vacuum, from the
fact that a vacuum was first produced in this manner by
an Italian philosopher, named Toricelli. It is not an
absolute vacuum, a small portion of mercury being al-
ways present in the space in the form of transparent
vapor.
191. BOILING. — Thus far we have con-
Whatismeant ••,-,,,,,, . /, f
by the term sidered solely the formation of vapors from
boiling? the surfaces of liquids< But where any
liquid is heated up to a certain point, vapor forms in
bubbles below its surface. The production of vapor
with ebullition is called boiling.
BOILING.
81
192. Water begins to boil when it is
What is the
boiling point heated up to 212° ; alcohol, at 173° ; and
OfWethcr ' ? ether, at 96°. As the proper temperature is
Of alcohol ? first reached at the bottom of the vessel,
near the fire, the formation of bubbles begins there ;
and as the surplus heat comes in below, they continue
to be formed at this point.
Every liquid has its own boil-
ing point.
How much 193. EXPAN-
stcam do cubic SION m BOILING.
inches of wa-
ter, alcohol, A cubic inch of
and ether re- , ., -, .
spcctiveiy pro- water boiled in
dnce? an Open vessel,
produces 1696 cubic inches
of steam. A drop one-tenth of an inch in diameter,
would make enough to fill a vessel of the diameter
of one and a fifth inches. A cubic inch of alcohol
produces about 500 cubic inches of alcohol vapor ; one
of ether about 250. The ether vapor is most dense,
that of alcohol next, and the steam
least so.
194. DISAPPEARANCE OF
HEAT IN BOILING. If a
thermometer be held in
boiling water, it indicates
a temperature of 212° F. Continue
the fire, and although heat constantly
passes up into the water through the
bottom of the vessel, it grows no hot-
ter. The steam which is produced has
4*
What is said
of the disap-
pearance of
heat in boiling?
82 HEAT.
also precisely the same temperature. Neither water
or steam are hotter, although both have been con-
stantly taking in heat. But the heat has not been
without effect, any more than in the conversion of a
solid into a liquid. It has combined with the liquid
to form the steam. In this case, also, the heat which
disappears is called latent heat.
195. RELATION OF PRESSURE TO BOIL-
Howdoespres- ING. — In order that a bubble of steam may
sure oppose f . .
boiling ? form, it is necessary that a small portion
of water, shall expand into a comparatively
large portion of steam to form it. But the atmosphere
is constantly pressing on the surface of the water, and
acting through the water, in all parts of the vessel, to
prevent any separation of particles or expansion. The
case is similar to that of a piece of india-rubber com-
pressed beneath a mass of iron : it cannot expand ow-
ing to the weight of the iron.
196. HEAT OVERCOMES PRESSURE. — But
Explain how
heat overcomes if we could by some means increase the
pressure. elasticity of the india-rubber, it would ex-
pand and lift the iron. So, if we can in any way in-
crease the tendency of the particles of water to sepa-
rate, it will finally be strong enough to overcome the
pressure of the atmosphere above arid affect separation.
Heat has this effect. As the water becomes hotter,
the tendency of its particles to fly apart becomes
greater and greater, till, at last, it is sufficient to over-
come the pressure which has before crowded them to-
gether, and a bubble of steam is formed. Others im-
mediately follow, and boiling thus commences. This
BOILING. 83
takes place at 212° Fahrenheit, which is therefore called
the boiling point of water.
197. EFFECT OF HEIGHT ON BOILING.
What effect . ...
has height on At great elevations, the atmosphere is, m
boiling? factj lighterj and there is iess of jt above
us, and the consequence is that water boils on moun-
tains, at a lower temperature than in the valleys below.
It is found, by careful observation, that an elevation of five
hundred and fifty feet above the level of the sea, makes
the difference of one degree in the boiling point.
198. MEASUREMENT OF ALTITUDES. —
the This fact once established, a tea-kettle and
mountains be a thermometer are the only requisites for
determined? . . . . r . mi
taking the height of a mountain. The
summit being reached, the tea-kettle is boiled, and
the heat of the water tested by the thermometer.
If the mercury stands at 211°, it is known that the
height is 550 feet ; if at 210°, the height is 1100 feet ;
and at whatever point it stands, it is only necessary to
multiply 550 by the number of degrees depression of
the mercury below 212°, to ascertain the elevation. On
the top of Mont Blanc, water was observed by Saus-
sure to boil at 184°. This gives us the means of calcu-
lating very closely the height of that mountain.
199. EFFECT OF DEPTH ON BOILING. —
What effect
kas depth on In mines the atmosphere is heavier, and
oihng? there is, beside, more of it above us, than
at the surface of the earth. Water must, in consequence,
be more highly heated before it will boil. 550 feet
makes, as before, a difference of one degree. We are
thus provided with a simple means of determining the
84 HEAT.
depth of mines. Owing to various causes, the atmo-
sphere at the same elevation is a little heavier some
days than others, so that the height of a mountain or
the depth of a mine, as thus measured, would not be
always precisely correct.
200. ARTIFICIAL CHANGE OF BOILING
POINT- — I* is obvious, from what has already
of liquids be been stated, that all it is necessary to do to
changed? , ...
change the boiling point, is to change the
pressure of the atmosphere, on the surface of the water
to be boiled. To produce this change of pressure, it is
not necessary to ascend mountains, or to descend into
mines ; it may be done by removing the atmosphere
by artificial means. This would be done by attaching
a tube, air-tight, to the mouth of a test-tube or
flask and drawing off the air by means of an J^
air pump. Cold water may thus be caused to
boil. So by pumping more air into the flask, the
pressure would be increased, and the boiling point
elevated ; and by this means boiling water
would be prevented from further boiling. This
subject is further considered in paragraph 204.
201. CULINARY PARADOX. — Boil some wa-
Descnbe the , . .
culinary par- ter m a test-tube, and then cork it tightly,
while steam is still issuing from its
mouth. Though removed from the fire, the wa-
ter will still continue to boil. This will behest
observed by inverting the tube, as the bubbles of
steam form more rapidly from the cork surface
than from the glass. A few drops of cold water
sprinkled on the tube will occasion a more violent
STEAM. 85
ebullition ; while on the other hand, boiling water,
or the application of flame, will cause the boiling to
cease.
202. EXPLANATION.— The principle is
e^ tne same as m tne experiment of the last
the culinary paragraph. As the steam condenses, by
paradox. r . . .J
the cooling influence of the air, a partial
vacuum is produced, and a diminished pressure, which
enables the water to boil with less heat. Cold water,
by condensing the steam and removing the pressure
more perfectly, increases the ebullition, while boiling
water or flame renews the steam, and consequent pres-
sure, and therefore checks boiling.
203. WATER HAMMER. — The test-tube
" Water Ham- prepared as above, is a simple form of the
" water hammer." If very thoroughly
cooled, and then sjiaken with the kind of motion which
would be required to make a bullet rise half way in
the tube and fall again, the water will strike like lead
on the bottom. It is because there is no air and but
little vapor present to break its fall.
204. SUGAR BOILING. — When syrup
Now may sy- .,.,,, , ,.
rup be boiled is boiled down under the ordinary pres-
z. gure Qf tne atmosphere, it is apt to be
browned or injured in flavor. By boiling it in a pan
with an air-tight lid, and pumping off the air, and the
vapor as fast as formed, boiling may be easily effected
at a temperature as low as 150°. This method is put
in practice by sugar boilers, and the disadvantages above
mentioned are thus avoided.
86 HEAT.
205. In cooking, this method could
Can food be
cooked by the not be employed. The water might, in-
same method ? ^^ be made tQ boil ftt lgOOj bm the boiling
water, owing to its less heat, would not have the effect
of water boiling at 212°. Many vegetable juices and
infusions which are used for medicines, and would be
injured by a high temperature, are boiled down, like
sugar syrup, under diminished pressure.
206. SlNQING OF THE TEA-KETTLE.
ringing of the The singing sound which precedes boiling ,
tea-kettle. ^ owing to the collapse of the first bubbles
of steam, as they rise into the colder water above.
The very first bubbles that form are not steam, but air
which the heat expels. Steam bubbles are then formed,
which rise a little way, and, being reconverted into water,
contract, and finally collapse. If the heat is continued
and the water made hotter, the next are able to rise
further. Finally, when the water becomes as hot as
the bubbles, they make their way through, and boiling
is thus commenced.
What is a 207. STEAM BOILERS. — The boiler is the
steam boiler? vessel in which steam is formed. From
the boiler it passes to other parts of the apparatus to
move the machinery. Steam boilers
are of various forms, but are always
made of great strength, to resist the
internal pressure to which they are
subjected.
Explain the 208. The figure repre-
sents an or(jinary steam boiler, with
STEAM. 87
the pipe which conveys the steam to the engine. A
safety-valve is also represented, which will be more
fully explained in another paragraph.
209. ELASTIC FORCE OF STEAM. — Under
How great is .
the elastic ordinary circumstances, the elastic force of
force of steam? steam is obviously equal to the elastic force
or pressure of the atmosphere. A man who rises from
a chair with a fifty-six pound weight on his shoulder,
must exert an extra muscular force, equivalent to fifty-
six pounds, in rising ; and he must continue to exert it
while he stands. So every bubble of steam must have
an elastic force equal to that of the air which it lifts, or
it cannot be formed under the pressure of the atmo-
sphere, or continue to exist when once formed.
210. ELASTIC FORCE, HOW INCREASED.
As lonS as the vessel> in which steam is
steam 'incrcas- made, is open, the pressure is as stated in
the last paragraph. But if the boiler be
closed steam-tight, and the heat continued, more steam
forms, and, crowding into the same space above the
water increases the pressure. In other words, the space
becomes filled with denser steam, of greater elastic
force ; and the force is finally sufficient to burst the
boiler, unless it can find some vent.
211. INCREASED TEMPERATURE ACCOM-
panies in™™ PONIES INCREASED PRESSURE. - Steam of
creased pres- high elastic force can only be made in a
sure of steam ?
close vessel. But in proportion to the
increase of elastic force, is the increase of pressure on
the surface of the water. Therefore, the boiling point
becomes higher and higher, or, in other words, the wa-
88
HEAT.
ter has to grow constantly hotter, in order that steam
may form ; and as steam always has the temperature
of the water with which it is in contact, the steam
grows constantly hotter also.
212. THE EXACT RELATION OF TEMPE-
How can the
exact relations RATURE TO PRESSURE. It is desirable to
iLr^STpre*- know tne increase of pressure for each ele-
sure be deter- vation of temperature. A steam boiler sup-
mined? ,. . . . _r
plied with a barometer guage and a thermo-
meter affords the means of ascertaining this rela-
tion. Or it may be done by a very small boiler, made for
the purpose. The barometer guage is nothing more than
a bent tube fitted into the boiler, open to the air at the top,
and containing quicksilver in the lower part of the bend.
We will suppose all the air to have
been expelled from the boiler, the stop-
cock through which it made its escape
closed, and the whole interior to be
filled with steam. As more steam is
produced, pressure is increased, and
the temperature of both water and steam rise, as before
explained.
What pressure 213. Where the temperature has
has steam at reached 250°, it is found that the pres-
2oO . at <zti o ?
at 294 ? How sure of the steam, acting through the water
on the quicksilver, is sufficient to force and
hold the latter thirty inches higher in one arm of
the tube than in the other. But the steam with which
the globe was filled when the stop-cock was turned, ex-
erted a pressure of fifteen pounds per square inch, just
sufficient to balance the pressure of the external air, and
STEAM. 89
prevent its forcing the quicksilver before it and crowding
into the boiler through the tube. As before stated, when
the thermometer reaches 250°, it is found that the denser
steam will not only balance the atmosphere, but has
force enough to lift the mercury thirty inches, which is
equivalent to another atmosphere. Steam at 250°, and
in contact with water, is therefore said to exert a pres-
sure of two atmospheres, or thirty pounds to the square
inch. At 275° it has a pressure of three atmospheres j
and at 294°, of four.
What is said 214. ALL VAPOR HAS ELASTIC FORCE.
%rcfofvaStors The aPParatlls Just described shows the
at low tem- pressure of steam at and above 212 degrees.
per But vapor of water has elastic force at all
temperatures. This is best shown by passing a little
water up into a Toricellian vacuum, and observing the
effect. The water is introduced by blowing it
through a glass tube, one end of which is brought
under the mouth of the inverted tube. The
drop rises and floats on the mercury, and as
vapor forms at all temperatures, a portion of
it is immediately converted into vapor. At
the same time the level of the mercury is de-
pressed. It is crowded down in opposition to
the pressure of the air outside, by the elastic
force of the vapor formed. For the sake of
simplicity, the space above the mercury was
supposed to be a vacuum, but the effect is the
same as if it is filled with air. For, as has
been already shown, vapor is produced as well in
air as a vacuum, and with the same elastic force. If
the top of the tube is warmed, denser vapor is formed
90 HEAT.
possessing greater elastic force, and the mercury sinks
lower, till at 212° the elastic force within, is equi-
valent to the pressure of the atmosphere without, and
the mercury is pressed down to the external level.
Explain the 215. BAROMETER-GUAGE. — The princi-
construction ^tle of the barometer-guage has already
and use of . &
the barometer- been explained. A few words will be
guage. added here as to its use and construc-
tion. It is always desirable to know the pressure
in a steam boiler, as an evidence of safety, and in
order that the fires may be regulated accordingly,
and no more fuel be consumed than is necessary.
Sometimes the tube containing the quicksilver is of
glass, and then the height of the mercury can be seen.
In other cases it is made of iron, and the change of
level of the quicksilver is indicated by a float.
216. OTHER STEAM GUAGES. — A ther-
Explain the
thermometer- mometer may be made to answer, perfectly,
guage. ^Q purpose of a steam guage, as is evi-
dent from what has been said in paragraph 213. The
advantage of such a guage is, that it takes but little
room ; its disadvantage, that it is liable to be broken.
217. There is still another kind of guage,
Explain the .
prfndpie of m which the force of the steam operates
another guage. on a metallic spring, which moves an index
more or less, according to the pressure. The spring
guage is commonly used in locomotive boilers.
Explain the ^18. ACTUAL PRESSURE IN DIFFERENT
di/erence be- ENGINES. — The actual pressure of steam,
twefn high and .
low pressure used in different forms of the steam en-
gine, varies very widely. There are low
THE STEAM ENGINE. 91
and high pressure engines. In the former, steam of
ten to thirty pounds effective pressure is used ; in the
latter, the pressure often reaches, and sometimes ex-
ceeds, seventy-five pounds. To measure the pressure,
the steam guage described in paragraph 215 would have
to be five or six feet long. It is on account of this in-
convenient length, that other guages are often substi-
tuted.
Whatismeant 219' EV effective pressure, is meant the
by e/ective surplus over and above that which is neces-
pre sary to counterbalance the pressure of the
atmosphere, or that of the uncondensed steam, on the
opposite side of the piston.
„ , . , 220. SAFETY-VALVE. — The safety-valve
Hixplam ana
illustrate the is a contrivance, by means of which the
PthTsafetij steam finds vent through a hole in the
valve. boiler, whenever its force becomes too great
for safety. A piece of metal shaped
somewhat like a decanter stopper, fits
into the hole above mentioned, and is
loaded by a weight, which can be made ,
greater or less at pleasure. As long as the steam has
not too great pressure, the stopper continues in its
place, and the boiler is as tight as if it had no such
opening. When this pressure is exceeded, the valve is
lifted, and stearn escapes. The stopper, being loaded,
falls back again, as soon as the pressure is relieved.
221. THE STEAM ENGINE. — The power
Explain the . . , . .
principle of applied in the steam engine is the elastic
ttetteamen- force of steam. The figure represents a
cylinder and close fitting piston, and tubes
92 HEAT.
through which steam maybe admitted at pleasure, either
above or below. When the valve in the
lower tube is opened, the steam under pres-
sure in the boiler, expands and enters the cyl-
inder, lifting the piston. If the steam is next
admitted above, it drives the piston back
again, and the latter may thus be kept in con-
stant motion, and made to move wheels,
shafts, or other machinery. It is only necessary, that
whenever steam enters, that which is on the other side
of the piston shall find its way out, into the air. Valves
are provided for this purpose, which are opened and
closed, at the right time, by the machinery which the
piston itself moves.
222. HIGH PRESSURE ENGINE. — The en-
Whatisahigh
pressure en- gine, here described, is called the high pres-
sure engine. The steam which moves it,
must evidently have elastic force greater than that of
the atmosphere, or it cannot expand and drive out the
waste steam, in opposition to the elastic force of the
air. Steam of much higher pressure is used in such
engines, than in those to be next described, and hence
their name.
223. Low PRESSURE ENGINE. — The
same fiSure wil1 answer to illustrate the
\ow pressure engine. The difference is,
sure engne. , ., .
that the steam which has been used is
not driven out. but disposed of, on the spot, by con-
verting it into water. The advantage of this will
be readily perceived. Suppose the space above the
piston to be full of steam. A jet of water is made to
THE STEAM ENGINE. 93
play into it and condense the steam, and thereby pro-
duce a vacuum. When, immediately afterward, steam
is admitted below the piston, the latter has nothing on
the other side to drive out, and consequently rises more
easily. As less force is required, steam of lower pres-
sure may be used, with a corresponding economy of
heat and the fuel required in its producton.
224. THE CONDENSER. — In steam en-
we'and' Object ginesj as now made, the water used to con-
ey the con- dense the steam, does not come into the
cylinder itself, but into a side vessel, called
the condenser. The steam expands into this vessel, and
is condensed, producing a vacuum in the cylinder
itself, as effectually as if the water were there intro-
duced. The object of the modification is to avoid
cooling the cylinder, and thereby diminish the ef-
fect of the steam subsequently entering from the
boiler. This engine is called the low pressure engine,
from the fact that steam of lower pressure may be em-
ployed to move it than is the case with the engine pre-
viously described. It may, indeed, be made to run
with vapor formed below 212°, instead of steam. But
in practice, steam of from ten to thirty pounds effective
pressure is employed.
225. ORIGINAL STEAM ENGINE. — In the
original low original form of the steam engine, the pres-
presmrecn- sure of the atmosphere, instead of steam,
was applied on one side of the piston, and
it therefore received the name of the atmospheric engine.
Suppose the cylinder in the last figure to be open at
the top, and the piston at its full height. On condens-
94 HEAT.
ing the steam below it, the piston would evidently sink,
in consequence of the pressure of the atmosphere. By
thus employing steam pressure on one side, and atmo-
spheric pressure on the other, a constant motion would
be realized. But the effective power would evidently
be less than in the low pressure engine, because part
it would have to be expended each time in lifting
the piston, in opposition to the pressure of the atmo-
sphere.
226. A test-tube provided with a pis-
Tfrrtlfiin the
. f ton made of cork, or better of w^ood w^ound
figure.
with cotton, suffices perfectly to illus-
trate the source of power in the steam engine. On
boiling a little water in the tube, the
piston rises. On dipping it into cool
water, and thus condensing the steam,
the piston is forced down to the bot-
tom, as in the original form of the
low pressure engine. In the ascent
of the piston, the analogy is not
perfect ; for it is, in this case, the
production of new steam, and not, as in the steam en-
gine, the expansion of steam already produced, that
causes the piston to ascend.
227. STEAM USED EXPANSIVELY. — It is
Explain the
action of steam not necessary in the steam engine, that
steam be made to flow from the boiler du-
ring the whole movement of the piston,
from one end of the cylinder to the other. When the
cylinder is partly filled, the supply is cut off, and the
steam already introduced forces the piston through the
STEAM. 95
remainder of the distance, by its own expansive force.
By this arrangement, instead of using a cylinder full
of steam at each movement of the piston, only one-
fourth, or even less, according to its density, suf-
fices. Steam employed in this manner is said to be
used expansively. The term is applied especially to
this case, although it is a fact that steam always acts
expansively.
228. CONVERSION OF VAPORS INTO LI-
pors convened QUIDS.— If a vapor, in any way, loses its
into liquids? latent heat, it at once becomes liquid. If,
for example, steam be led into a cool pipe,
the metal abstracts the latent heat, and the steam be-
comes water. At the same time, the heated pipe im-
parts warmth to the air around it.
229. HEATING HOUSES BY STEAM.—
How are
houses heated Houses are thus heated, by steam pipes
passing through the various apartments.
The pipes abstract the heat, and give it out again to the
air of the house. The steam thus converted into wa-
ter, runs back into the boiler to be reheated, and to start
again on its journey. And as long as heat is supplied,
the water continues its service as a carrier of heat.
230. WATER HEATED BY STEAM. — When
How is water
heated by steam is led into water, the effect is the
same as on leading it into a cold pipe.
The water abstracts its latent heat, and becomes hot,
while the steam itself becomes additional hot water.
Water in different parts of a room, or even of a large
manufacturing establishment, may thus be made to
96
HEAT.
boil by one fire ; steam being led into it, by long pipes,
from a single boiler.
Prove that 231. PROOF THAT BOILING IS EFFECT-
boihng tsef- ED BY LATENT HEAT.— No amount of boiling
fected by la-
etnt heat. water, if poured into cold water, will make
it boil. But steam no hotter than the boiling water, if
led into cold water, will have this effect. Now, as both
the hot water and the steam were the same in respect to
sensible heat, if the steam effects what the water does
not, it is evident that it must do it by hidden, or latent
heat. It is only latent heat which the steam loses, for
it becomes itself converted into equally hot water.
232. QUANTITY OF LATENT HEAT. - A
How much la- .
tent heat does pint of water will make enough steam
steam contain? t() fiu ft globe ^^ f()ur feet m diameter<
If this amount of steam could suddenly become a pint
of water, and be prevented from flying off into steam
again, it would become red hot. The latent heat of the
steam would have raised the temperature from 212° to
1212° — a thousand degrees. Steam is therefore said to
contain 1000 degrees of latent heat. Vide App.
233. SUM OF SENSIBLE AND LATENT
HEAT ALWAYS THE SAME- — Vapor formed
sensible to la- by the heat of summer, occupies more space,
tent heat? 7, ,.
and contains more heat, in a latent condi-
tion, than is contained in steam. And it is found to be
a universal fact that, just in proportion as vapor or
steam feels cool, or indicates a lower temperature to
the thermometer, it contains more latent heat to the
same quantity of water. The sum of the sensible and
latent heat is always the same -about 1200° degrees.
DISTILLATION. 97
Why is there ECONOMY IN EVAPORATION. It fol-
no economy in lows that evaporation at low temperatures.
evaporating at .
low tempera- such as is practiced sometimes in sugar-
houses, has no advantage of economy.
The vapor that passes off, carries with it less sensible
heat, but enough more latent heat in proportion, to make
up the difference.
235. DISTILLATION. — Distillation con-
Descnoe the
process <>/ dis- sists in converting a liquid into vapor, and
recondensing the vapor. The apparatus
represented in the figure,
suffices for illustration.
Water being boiled in the
test-tube, the steam con-
denses in the cooler vial.
If the latter be covered
with wet paper, the con- "~
densation is more perfect. The apparatus commonly
used in distillation, consisting of retort and receiver, is
represented in the appendix.
236. OBJECT OF DISTILLATION. — The ob-
object*} *&%> Ject °f distillation is commonly to purify,
tiilationf Or, in other words, to separate the liquid
distilled, from other substances with which
it may be mixed. Thus, sea water is distilled to sepa-
rate the pure water from salt. The water becomes
steam, and is condensed as pure water, while the salt
remains behind. So alcohol is distilled, or converted
into vapor, and recondensed, to separate it from water,
and the various refuse matters which are mixed with
it after fermentation. But the separation is not per-
5
HEAT.
feet, for, althougn alcohol is more volatile, and distils
more rapidly, a portion of water always distils with it.
Distilled liquors, therefore, always contain a certain
proportion of water.
MAGNETISM. 99
CHAPTER IV.
ELECTRICITY AND MAGXETISM.
237. NATIVE MAGNETS. — The native mag-
What proper-
ties has the na- net, or loadstone, is a mineral which has
tive magnet? the remarjcable property of attracting me-
tallic iron to itself, and of taking north and south di-
rection, when suspended and free to move. Particles
of iron brought near, rush toward it, and remain at-
tached to its surface, without any visible cause. It ex-
erts this attractive force just as well through wood,
stone, or any other material, as through the air.
23$. ARTIFICIAL MAGNET. — The same
Describe an . 1-1 •
artificial mag- properties may be imparted to a piece of
steel, by a process to be hereafter described.
Such a piece of steel thereby becomes itself
a magnet. Magnets are often made of a shape
approaching that of a horse-shoe, the two
poles being brought near to each other. A
piece of soft iron, called an armature, is placed across
the end to prevent the loss of magnetic power, which is
found otherwise to occur.
239. MAGNETIC NEEDLE. — If a steel bar
What is the
magnetic nee- be made into a magnet, and then balanced
on a pivot, it will turn, until one end points
north and the other south. That which ^
moves toward the north is called the north
pole, and the other end the south pole.
A small bar thus balanced is called a mag-
too
MAGNETISM.
netic needle, and is the essential part of the mariner's
compass.
240. ATTRACTION OF MAGNETS FOR EACH
How do the .
poles of mag- OTHER. — The law of attraction between
'each^tter? magnets is, that unlike poles attract, and
like poles repel. The north pole of one
magnet, therefore, attracts, and is attracted by the south
pole of another.
241. WHY THE MAGNETIC NEEDLE POINTS
In^gneriT nee- N°RTH. — In accordance with the law stated
die point in the last paragraph, the tendency of the
noTth ?
magnetic needle to point north, may be ac-
counted for by supposing the south pole of an enor-
mous magnet, to exist somewhere near the north pole
of the earth. If we call the end of the needle which
points north its north pole, it is evident that the sup-
posed pole at the north must be a south pole. For the
same reason, xve might suppose the north pole of an
enormous magnet to exist near the south pole of the
earth. Connecting these poles, we should accordingly
have an immense magnet running through the earth
from north to south. This supposition will account
for many of the phenomena of magnetism ; but it is
not supposed to be the true one. Another theory is
presented in a subsequent paragraph.
242. INDUCED MAGNETISM. — When a
Sio;To/~ Piece °f *ron is brought near to a magnet,
magnetism, in the iron receives magnetism, by induction,
soft iron. ., . . ., .,
and becomes itself, temporarily, a magnet.
If approached to the south pole, its adjacent end ac-
MAGNETISM. 101
quires north, and the remote one south polarity, and
mutual attraction results. By virtue of its ac-
quired or induced magnetism, it will attract an-
other piece of iron, as is represented in the figure,
and affect it in all respects similarly. From the
second key, another smaller one may be sus-
pended, and from this another, and so on. It is
only necessary, that each successive object shall be
smaller than the one to which it is attached. The
magnetism thus acquired is only temporary in the case
of iron, but in the case of steel it is, in some degree
permanent, and may, by the proper means, be rendered
entirely so.
243. DIAMAGNETISM. — If a needle of
What is said jron be hung, by a thread, between the
of diamagnet- J
ism? poles of a horse-shoe magnet, it immedi-
ately turns, so that one of its ends points
to the north pole, and the other to the south. This
is also a consequence of induced magnetism, as ex-
plained in the preceding paragraph. The metal nickel,
oxygen gas, and many other substances, both solid,
liquid, and gaseous, are similarly attracted by the
poles of a magnet, though in a much less degree. All
bodies which are not attracted are repelled, and if sus-
pended between the poles, turn so as to bring their ex-
tremities as far away from the poles as is possible.
The former class are called magnetic, and the latter
diamagnetic bodies. To show the phenomena of at-
traction and repulsion with gases and liquids, the mate-
rials are inclosed in tubes or bulbs. In the case of most
substances, excepting iron, these effects can only be at-
102 ELECTRICITY.
tained by means of powerful magnets and delicate ap-
paratus.
ELECTRICITY.
244. FRICTIONAL ELECTRICITY. — If a
tional dectri- glass tube be rubbed with silk, it will after-
city? ward attract to itself filaments of the silk,
as a magnet attracts iron. Or, if the knuckle be ap-
proached to the tube, a spark may be drawn from it.
These phenomena are called electrical. Both glass and
silk are said to be electrically excited. The same ex-
periment may be made with a stick of sealing-wax.
State the theory 245. THEORY OF ELECTRICITY. AcCOrd-
of electricity. jDg to fae vjew COmmonly entertained of
these phenomena, both glass and silk contain two electri-
cal fluids in a state of combination, which are so sepa-
rated by friction, that the positive fluid of both ac-
cumulates in the glass, and the negative in the silk.
The positive sustains the same relation to the negative,
that the north polarity of a magnet does to the south ;
and, in consequence of the difference of the separated
fluids, the two bodies containing them attract like op-
posite poles of a magnet. It is also true, that similarly
electrified bodies repel like similar poles of magnets.
As in the case of heat and light, we know nothing of
the electrical fluid, save by its effects.
Illustrate by ^46. The human body may also be elec-
examples. tricially excited, so as to yield a spark, by
rapid sliding over a carpet. Gas may be lighted by the
spark. The gas in certain manufactories is instantane-
GALVANIC ELECTRICITY. 103
ously lighted throughout the whole establishment by
electricity developed by the friction of the machinery.
247. CONDUCTION OF ELECTRICITY. — Like
Explain the . .
conduction of heat or caloric, electricity may be conducted
electricity. ^Qm Qne body tQ another< ThuSj if ft piece
of metal be electrically excited, or, in other words,
charged with a quantity of either the positive or nega-
tive fluid, another piece of metal will immediately be-
come so on connecting it with the first by a metallic
wire. The connection being formed, it will attract or
repel filaments of silk or other material, precisely as the
first one does. The fluid is supposed to flow from one
piece of metal to the other, through the wire, and we
therefore speak of a current of electricity. But it is
not certain that any thing actually passes, any more
than in the case of light and heat before considered;
248. GALVANIC ELECTRICITY. — It is also
What is gal-
vanic electri- found that electricity is developed when
Clty ? two metals are placed in contact with each
other, and with an acid at the same time, < ««
as is represented in the figure. This is
called galvanic electricity, from the name
of an early experimenter in the science.
The acid acts on the zinc, arid the cur-
rent flows continuously in the direction
indicated by the arrows. This apparatus is the sim-
plest form of the galvanic battery.
,„, . . 249. ELECTRODES. — For convenience in
What is an
electrode ? certain experiments, it is customary to at-
tach platinum wires, to the exterior portions of the me-
tallic slips. These are called electrodes. The wire con-
104 GALVANIC ELECTRICITY.
nected with the copper forms the positive electrode, and
the one attached to the zinc, the negative.
250. Platinum wire is chosen, because
Why is plati-
num used for there is frequent occasion to immerse the
electrodes ? electrodes in corrosive liquids, and this me-
tal, for the most part, withstands their action. For
many experiments, it is found best to flatten the ends
of the wires forming the electrodes, so as to produce
a larger surface. The same object may also be effected
by terminating them with strips of platinum.
251. ELECTRICAL CONDITION OF ATOMS.
What is the ,, .. , . .
electrical con- All atoms of matter are regarded as origi-
datoms°^ nally charged with either positive or nega-
tive electricity. Hydrogen and the metals
are electro-positive ; oxygen, chlorine, and cyanogen,
and other substances, to be described hereafter, are ne-
gative. A molecule of water is made up of a positive
atom of hydrogen, and a negative atom of oxygen ;
hydrochloric acid, of positive hydrogen and negative
chlorine ; oxide of silver, of positive silver and nega-
tive oxygen. The figure, in which +' represents
positive and — negative, may represent a mole-
cule of either of the compounds named.
252. QUANTITY OF ELECTRICITY. — The
What quanti- .
ty of electrid- quantity of electricity thus combined or
Ziwa™rt?ned neutralized, in almost all kinds of matter,
is enormous. Faraday has shown that
a drop of water, contains more than is discharged in
the most violent flash of lightning.
The terms atomt and molecule, .ire synonymous. But "molecule" is
limited, in the present work, to the'particle of a compound.
GALVANIC ELECTRICITY.
105
253. DECOMPOSITION OF WATER. — If the
Describe the .. .
decomposition electrodes are immersed in water, as repre-
of water. ^^ in the figur^ the
water is decomposed, and separated
into its elements. Bubbles of hydro-
gen collect on the negative electrode,
and bubbles of oxygen on the posi-
tive, and finally disengage themselves,
and rise through the water.
254. It is to be observed that positive
Why does hy- . , -1-1
drogen appear hydrogen is liberated at the negative pole,
as if the latter had a Power analogous to
that of the magnet for iron, to draw the
hydrogen out of the water, in which it exists combined.
On the other hand, negative oxygen is liberated at the
positive pole, as though the latter had the same attrac-
tive power for oxygen. The above figure is given
solely for the purpose of illustration. The actual form
of apparatus for decomposing water, by the galvanic
current, is described in a subsequent paragraph.
255. THEORY OF THE DECOMPOSITION OF
Give the theo- .
ry of the de- WATER. — It is a remarkable circumstance,
™™%!sition °f in the decomposition just described, that it
continues to occur even when the elec-
trodes are quite widely separated from each other. Now,
a molecule of water is extremely
small, and cannot occupy the space
between the electrodes, if they are
separated to any considerable ex-
tent. The space must be occu-
pied by many such particles, which,
5*
106 GALVANIC ELECTRICITY.
for the sake of definiteness, we will conceive of as ar-
ranged in straight lines, between the two electrodes.
The circles iiUhe figure, inscribed H and O, represent
one of these lines of molecules. The difficulty now
arises, to account for the fact, that when the hydrogen is
liberated at the negative pole, the oxygen, combined
with it a moment before, is not also liberated at the same
point. The view to be taken of it is as follows : that as
soon as the atom of oxygen loses its hydrogen, it combines
with the hydrogen of the next molecule of water.
The oxygen of this second one being thereby liberated,
combines with the hydrogen of the next ; and this
decomposition and recomposition continues throughout
the series. The end of the series being reached, the
last oxygen atom escapes in the form of gas. The action
being simultaneous throughout the series, this evolution
occurs at the instant that the hydrogen is set at
liberty at the negative electrode. It is, therefore,
quite as proper to give the explanation of the diffi-
culty first stated, by beginning with the liberation of
oxygen at the positive electrode, and supposing the
hydrogen to combine with the oxygen of the next
molecule of water in the series, and so on to the nega-
tive electrode, where hydrogen is evolved. The ac-
tion is, in fact, as before stated, simultaneous.
256. DEPOSITION OF METALS. — The me-
Explain the . . .
deposition of tals are electro-positive. Oxygen, chlorine,
™niLbygal' &c'' on the other hand> are negative. If,
therefore, oxides, chlorides, or cyanides
of the metals are subjected to the action of the
electrodes, they are decomposed, while the metal
ELECTRO-PLATING. 107
goes to the negative, and the oxygen, chlorine, or
cyanogen, to the positive. But the metals, when sepa-
rated from their combinations, being solid bodies, can-
not escape. They collect on the negative electrode, in-
stead. If this be attached to a brass spoon or fork, or
any other object it is desired to plate, the spoon be-
comes itself the electrode, and the metal is deposited
upon it as long as the action of the battery continues.
At the same time, the oxygen, or other negative ele-
ment, goes to the positive electrode, generally cor-
roding it, instead of passing off as gas.
257 . SILVERING APPARATUS. — The re-
W hat appara- .
tue is required quirements for electro-silvering or gilding,
are first> a batterY of somewhat different
form from that already described, though
precisely the same in principle ; second, an acid to ex-
cite it ; and third, a solution containing gold or silver.
These will be described in turn.
258. A convenient form of the
apparatus is represented in the fig'i
are, and may be prepared from
sheet zinc and copper in a few mo- -^
ments. It consists of a bent strip
of the former metal, with a strip of copper
thc fastened between the two portions. The
metals should be within an eighth of an
inch of each other, but without contact. To secure
this, they are tied together with thread, bits of wood or
cotton cloth being previously interposed. Copper
wires being attached to the zinc and copper, as rep-
resented in the figure, the apparatus is placed in a com-
mon tumbler, and the battery is complete.
108 GALVANIC ELECTRICITY.
259. Before combining the battery as
How and why ......
is the zinc above described, it is best to wash the
zinc with soaP and water> and afterward
with dilute sulphuric acid, and then to
immerse it for half a minute or so in a solution of ni-
trate of mercury. By this process, the zinc acquires
a thin film of quicksilver, which afterward protects it
from the action of the acid used to excite the battery,
excepting when the current is completed. When the
battery is in operation, it also has the effect of making
the action, more equal and constant. It is then to
be again washed, and newly immersed in the acid solu-
tion. This solution is prepared by dissolving quicksil-
ver, of the bulk of two peas, in nitric acid, and pouring
the clear liquid into a tumbler of water.
260. THE EXCITING ACID. — The exci-
How is the ex- . .
citing acid ting liquid is dilute sulphuric acid, consist-
preparc . .^ ^ Qne part Q.J ^ vitriol, to ten parts of
water. The acid is poured into the proper quantity of
water, and set aside to cool.
261. THE SILVERING SOLUTION. — To
How is the sil- . .
vering solution make a half pint of the solution, a dime is
prepared? placed in a test-tube and dissolved in ni-
tric acid, the solution being diluted with water. Muri-
atic acid is then added, which precipitates the silver, in
the form of a white curd. This is allowed to settle, and
the green liquid, which contains the copper of the coin,
is poured off. Water is again added, and the curd al-
lowed to settle ; this cleansing process is several
times repeated. The test-tube is then half filled with
water, and heated, and bits of cyanide of potassium ad-
ded, until a transparent solution is obtained.
ELECTRO-PLATING. 109
262. A solution for gilding, is prepared
How is the so- " _
lutionfor , by drying a solution of gold, at a moderate
heat> and dissolving it in cyanide of po-
tassium, as above described. The process
for gilding, is in all respects the same as that for the
deposition of silver.
263. THE PROCESS. — The battery and
How is the sil- ....
veriny process silvering solution being prepared, the cop-
conducted? ^ CQ^ or ^j^ object to be silvered, is
cleansed with potash, rubbed with chalk or rotten-
stone, and then attached to the wire proceeding from
the zinc. A silver coin is fastened to the other wire,
and immersed in the silvering solution ; acid is then
added to excite the battery, and the object to be silvered
is lastly immersed. It should be hung face to face with
the silver coin, and quite near to it, the two being kept
in their places by blocks placed across the tumbler, as
represented in the figure. The coin will receive a per-
ceptible coatingwithin a few minutes, and will be more
thickly covered, according to the time of immersion.
The deposit is hastened by keeping the solution mode-
rately warm. This is especially advantageous in the
commencement of the process. The newly plated sur-
face is without lustre, and requires burnishing after re-
moval from the solution.
264. OBJECT OF THE SILVER COIN. — The
What is the
object of the piece of silver is attached to the positive
wire, to maintain the strength of the solu-
tion. It is eaten away, and dissolved as fast as silver
is deposited on the objects connected with the negative
wire. The reason of this is, that the cyanogen of the
110 GALVANIC ELECTRICITY.
solution, when it goes to the positive pole, as before ex-
plained, combines with silver, forming new cyanide of
silver, which dissolves and mixes with the rest. Thus,
the strength of the solution is always maintained. The
coin is attached to the negative wire, by flattening the
latter, laying it on the back of the coin, and covering
the whole with sealing wax ; the coin and wire should
be previously slightly warmed, and the wax used at a
moderate heat, so that it shall not run between the wire
and the coin, and prevent their perfect contact.
How are med- 265. COPYING OF MEDALS. If it IS de-
ais copied? sired to copy the face of a medal or a coin,
the same apparatus suffices. The reverse and edges of
the coin are very slightly oiled, to prevent the adhesion
of the copy about to be made. It is then placed in the
solution. The metal deposits upon it, copying perfectly
every elevation and depression. When the crust is suffi-
ciently thick, which will be after the lapse of twelve
hours, the coin, with its shell of metal, is removed, and
the whole process repeated with the mould. The de-
posit which now forms in the shell, is an exact copy of
the face of the original coin. Moulds are also made by
stamping the coin into soft metal, and using the impres-
sion thus produced instead of the copper shell. Copper
plates, for engravings, may be copied so perfectly by
this method, as to be fully equal to the original.
How are wood 266. COPYING OF WOOD CUTS. — The diffi-
cuts copied? culty of copying other than metallic ob-
jects, by the processes, that they are not generally good
conductors. Thus, when a wood cut is attached to
the negative wire, it does not itself receive a nega-
ELECTRIC LIGHT. Ill
live character from the wire, and will not, therefore,
take positive metal from the solution. This is obvia-
ted by covering the block with a fine powder of plum-
bago or black lead, which has high conducting power.
267. This process is very extensively
It what cases r /
is the process practised. Where a large number of cuts
pra of the same kind are wanted, as for exam-
ple, to print labels for dry goods, only one engraving
on wood is made, and numerous copies are taken by
the above process, which is much less costly.
268. HEATING EFFECTS OF THE CUR-
Descrtbe the
heating e/ect RENT. — If the electrodes are connected
of Recurrent? while the battery js jn actlOn, the wire be-
comes heated more or less strongly, according to the
size of the plates. If the plates are very large, the
wire melts, even though it be of platinum, the most
infusible of metals. Gold may even be converted in-
to vapor by the same means. Carbon, supposed a few
years since to be entirely infusible may be also super-
ficially fused, and even volatalized between the electro-
des. It condenses again at a little distance, in the form
of microscopic crystals. Imperfect diamonds have been
thus artificially produced. With such a battery as
has been described the elevation of temperature would
be scarcely perceptible.
269. THE ELECTRIC LIGHT. — If the current
How is the .
electric light be allowed to pass between two points of
produced ? prepared charcoal, an exceedingly intense
light is produced, accompanied by great heat. Char-
coal is employed because it is a comparatively infu-
sible, and inferior in conducting power. A metallic
112 GAI VANIC ELECTRICITY.
wire, under the same circumstances, would melt, or if
too large to undergo fusion, would allow the current to
flow readily through it, without that detention which is
essential to the production of the above effects, in their
highest degree.
270. If the charcoal points be with-
How ts the ' , , . -,
electric flame drawn from each other, a splendid electric
produced? flame is produced between them. This
flame is not the result of combustion, for the char-
coal is extremely dense, and wastes away but slow-
ly. It is purely electric. Metals melt in it, and are
dissipated in vapor. A much larger battery than that
here described, is requisite fox the production of ei-
ther the light or flame. In experimenting with the
compound battery, hereafter described, a slight spark
will be observed, on separating the electrodes.
271. DECOMPOSITION IN THE BATTERY.
A decomposition, similar to that of wa-
in the battery ter and metallic compounds, as above de-
scribed, takes place in the battery itself,
and seems to be the source of its power. Suppose, for
example, the acid with which the zinc and copper are
in contact, to be hydrochloric, each molecule of
which is composed of an atom of hydrogen and
an atom of chlorine. The zinc becomes positive
where it is in contact with the acid, and negative at
the other end, the extremities assuming different states,
as in the case of a piece of soft iron suspended from a
magnet. The outer portion of the copper being in con-
tact with the negative end of the zinc, is, itself, nega-
tive, while the end immersed is positive. The atoms
GALVANIC ELECTRICITY. 113
composing the acid, are supposed to be arranged as rep-
resented in the figure. The alternation of positive and
negative, in copper, zinc, and the line of acid molecules
is analogous to the case of the sus-
pended keys. As long as the metals
are immersed, and made to touch, an
atom of zinc constantly combines
with an adjacent atom of chlorine.
It follows, that no chlorine is set at
liberty. As fast as each atom unites
with the zinc, its hydrogen combines
with the next chlorine, the hydrogen of this, with
the next, and so on, as before explained, in the de-
composition of water. Hydrogen is therefore con-
stantly given off at the surface of the copper. But
when the two metals are not in contact above the li-
quid, and the circuit is, consequently, not completed,
there is no negative influence exerted at the extremity
of the copper, and the series of decompositions, before
described, does not occur.
272. A SALT EMPLOYED AS EXCITANT
Explain how . •-,, -iini
a battery can It is not essential, that an acid shall be used
bamit?ed by as tlie excitmg liquid iii the galvanic bat-
tery. A metallic salt is sometimes em-
ployed. This may be best illustrated, by supposing
chloride of copper to be employed instead of hydrochlo-
ric acid, which is chloride of hydrogen. The chlo-
rine goes to the zinc, as in the previous case, and the
copper of the salt, to the strip of copper, placed in the
solution. Being a solid, it remains there, and en-
crusts the copper, instead of being evolved, as in the
case of hydrogen.
114
GALVANIC ELECTRICITY.
273. DIFFERENT KINDS OF BATTERIES.—
What is said . .. .
o/ the differ- There are different kinds 01 galvanic bat-
britertef teries, but the principle in all is the same.
Two of the forms in most common use
are described in the Appendix. Smee's battery is
especially recommended to the student, for its cheap-
ness, simplicity, and efficiency. It is very similar, as
will be seen, to the simple one which has been already
described.
274. COMPOUND CIRCUIT. — For the sake
What is said f . ,. . „ . f
of the com- ot simplicity, all the foregoing decomposi-
pound circuit? tions have been described, as a result of the
action of a simple voltaic circle, consisting of an acid,
and two metals. But, it is found that in many decom-
positions, the power of such a battery is insufficient.
The efficiency is increased by employing several single
batteries together, and bringing them all to bear upon
the same electrode.
How are heat- 275. The heating and magnetic effects
ing and mag- f fa battery are very ^cft increased by
netic effects J J J
produced? uniting the plates, as in the preceding fig-
ure, where all the zinc plates are joined together, so as
virtually to form one. The quantity of the current is
thus increased. Power of decomposition, and to give
shocks, such as are taken from an electrical machine,
GALVANIC ELECTRICITY.
115
are increased by uniting them as in the figure which
follows. The intensity of the current is thus increased.
What is the
meaning of in-
tensity ? Of
quantity ?
276. MEANING OF INTENSITY AND QUAN-
TiTY. — The terms intensity and quantity
are rather vaguely used, and do not de-
scribe as definitely as may be desired, the
different properties of the current. The student must
associate the term quantity with increased heating and
magnetic effects, and the term intensity, with power
of decomposition.
277. DECOMPOSITION BY THE COMPOUND
Explain the ...
apparatus for CIRCUIT. — Jb or the decomposition oi water,
a S6rieS °f Slx CUPS> Sllch aS haVG beetl al-
ready described for use in plating, will suf-
fice. They are to be united according to the second ar-
rangement. The zinc of each cup is to be connected with
the copper of the next in order, by a copper wire, forming
a good metallic contact. This being done, another long
wire is fastened to the first copper plate, and one, also, to
the last zinc, and bits of platinum wire or foil are attached
to their ends. A small test-tube is then filled
with acidulated water, and inverted in a cup,
also containing water and acid. The wires
are bent upward into the cup, as represented
in the figure. The battery being now set in
operation, by dilute acid, as before described,
116 GALVANIC ELECTRICITY.
the evolution of gas immediately commences from the
the platinum wires. This compound battery will be
found rather slow in its operation, and has been de-
scribed only for the purpose of illustrating the use of
the more powerful galvanic batteries of similar con-
struction. The student is advised to substitute for it
the Voltaic pile, as hereafter described.
278. AN EXPLOSIVE MIXTURE. — A mix-
What proper- „ , ,
ty has the ture of hydrogen and oxygen gases, in the
US proportion m which they are here evolved,
is explosive. This property is the evi-
dence that the gases are really oxygen and hydrogen,
in due proportion. A sufficient quantity being col-
lected, the mouth of the tube is covered with the finger,
the tube inverted, and a match applied at the mouth.
A slight puff is all the evidence that will be obtained
from a small quantity of the mixture. A test-tube full
will give a sharp report.
279. SEPARATE COLLECTION OF THE
How may the , . ,
gate* be col- GASES. — By using two test-tubes, instead
lected*cpa- of before described, and introduc-
rately ?
ing an electrode into each, the gases may
be separately collected and tested by the methods give
in the section which treats of those gases.
280. The water is acidulated in the ex-
Wky is the .
water to be de- penment, to make it a better conductor of
"dilated? the mmience which must pass through it,
from one electrode to the other, in order
that the decomposition may take place. The reason
for using platinum electrodes has already been given.
In the present case, if the copper wires themselves
GALVANIC ELECTRICITY. 117
were introduced, the negative electrode would appro-
priate all the oxygen to itself, thereby becoming grad-
ually converted into oxide of copper, and nothing but
hydrogen gas would be obtained.
281. DECOMPOSITION OF A SALT. — The
Describe the decomposition effected by the galvanic
decomposition * °
of a salt. current, may be more strikingly illustrated
by introducing the electrodes into a dilute
solution of sal-ammoniac, previously
colored by litmus, or red cabbage.
Chlorine is liberated at the positive
pole, and bleaches the solution in its
vicinity, while ammonia is evolved
with hydrogen, at the negative pole,
and changes the color of the solution from blue to red.
That of the cabbage is changed by the same means,
from red to green. By employing a glass box with two
compartments, such as is represented in the figure, the
two portions of the liquid may be kept distinct. It is
essential, for reasons that will be understood from the
preceding paragraph, that there be an unbroken chain
of molecules of the electrolyte, or substance to be de-
composed, between the electrodes. This is effected by
making the partition quite loose, and keeping it in its
place by strips of paper, placed along the edge. All the
communication that is essential, then takes place through
the pores of the paper, while the partition at the same
time prevents the mixing of the contents of the sepa-
rate cells. The same object may be accomplished by
the employment of two tea-cups, holding the liquids,
and connected by moistened lamp-wick ; a larger pile,
118 GALVANIC ELECTRICITY.
and a longer time, is in this case required to effect the
decomposition. The glass box may be made according
to the directions given in paragraph 33 for making a
prism.
Describe the 282. THE VOLTAIC PILE. — The first
Voltaic pile, form of galvanic battery ever produced is
represented in the figure, and is called the
Voltaic pile, from the name of its inventor.
It consists of a succession of discs of zinc,
copper, and cloth, moistened with acid, al-
ternating with each other, as represented
in the figure. Each series forms a simple
battery, and the whole pile is a compound
battery, essentially the same as that before
described. Wires to serve as electrodes are to be at-
tached to the extreme copper and zinc.
283. The enlarged form of the Voltaic
What is said ., „ ....
of the en- pile represented in the next figure will be
Voltaic found a mogt efficient apparatus for ef-
fecting decomposition. It is composed of
sixteen plates of each metal, each having a surface
of twelve square inches. The zinc should be amalga.-
mated, as before explained. Flannel, or any similar
material may be employed to separate the plates. With
this piece of apparatus, the spark is readily obtained, and
slight shocks may be taken by bringing the two hands
into contact at the same moment
with the top and bottom of the pile.
On terminating the electrodes with
fine iron wire, and frequently uni-
ting and separating them, scintil-
ELECTRO-MAGNETISM. 119
lations of the burning metal may also be readily pro-
duced. By increasing the number of the plates still
more striking effects are obtained. With a pile con-
sisting of six or eight plates a foot square, platinum
wire connecting the electrodes may be readily fused.
Such a battery is also more effectual in the electro-
magnetic experiments which follow.
Describe the 284. MAGNETIC PROPERTIES OF THE CUR-
magnetic pro- RENT> — jf the wire connecting the zinc
perties of the
galvanic cur- and copper of the galvanic battery be wound
in a spiral, as represented in the figure, the
coil, or helix, as it is termed, be-
comes possessed of magnetic
properties. Like a magnet, it attracts iron, and other
magnets, and according to the same laws.
How may a 285. THE SUSPENDED BAR. — A rod of iron
^ °endedlne Drougnt near one °f tne extremities of the
the air ? coil, is not only attracted, but actually
lifted up into the centre of the coil, where it re-
mains suspended without contact, or visible sup-
port, as long as the battery continues in action.
Science has thus realized the fable of Mahomet's
coffin, which was said to have been miraculously
suspended in the air. The helix, for this and
similar experiments, is wound closer than is rep-
resented in the figure, and is composed of several
layers of wire. A powerful battery is also essential to
success in this experiment.
286. POLARITY OF THE COIL. — That
What is the •'•••, i •
action of a such a coil has polarity, may be proved,
precisely as with a magnet. One end of
it attracts the north pole of a magnet, and
120
GALVANIC ELECTRICITY.
is therefore a south pole. The other end
attracts the south pole of a magnetic nee-
dle, and is therefore, itself, a north pole-
But the direction in which the current
moves round in the helix, determines
which shall be north, and which south..
As the current is represented to move
in the first of the two coils in the figure, the up-
per end of the coil is north, and the lower end south.
If it is made to move in the other direction, as in
the second figure, the poles are reversed.
287. CONSEQUENT MOTION or A sus-
Hoio may we
obtain motion FENDED COIL. — To obtain motion of the
°/eifke C°d li~ coil itself> as a consequence of its magne-
tism, it is necessary to suspend it ; and in
order to suspend it with perfect freedom of motion, it is
necessary to suspend the battery
with it. Such a suspended coil
and battery is represented in the
figure. In preparing it, the wire
is wound forty or fifty times
round a test-tube, (which is afterward removed,) and
copper and zinc plates then attached to the ends.
The plates are tied together with several layers of paper
between them, then dipped in acid, and the apparatus
carefully suspended by an untwisted silk fibre. The
acid absorbed by the paper, suffices to maintain for
some time the action of the battery. On approaching
a magnet to either pole of the suspended coil, it is at-
tracted or repelled precisely as if it were a magnet. In-
stead of suspending the apparatus by a thread, it may
ELECTRO-MAGNETISM. 121
be floated on acidulated water, by means of a cork,
and submitted to the same experiment. In this con-
struction, the wires proceeding from the end of the
coil, pass through the cork, before connecting with the
•metallic plates. The first described method of suspen-
sion is regarded as the best.
288. THE COIL A MAGNETIC NEEDLE.—
How may the
coil be conver- On floating a coil with extreme deli-
<=acy upon water, and protecting it from
all currents of air and water, it assumes
north and south direction, and becomes, in fact, a mag-
netic needle. This can only be accomplished by
means of a light glass cup, blown for the especial pur-
pose, and prolonged into a cone below, to give it stead-
iness in the water. This cup is filled with dilute acid,
in which the plates are immersed, and is then floated
in a larger vessel.
289. MUTUAL ACTION OF COILS. — Two
Describe the .
mutual action helices, or coils, such as are described in
the last paragraph, floating near each other,
attract or repel, precisely as if they were
magnets, according as like or unlike poles are brought
together. They finally attach themselves to each
other in the position represented in
the figure, lying parallel and with
opposite poles in contact. In this
position, it will be observed, that at thepoint of con-
tact, the currents are moving in the same direction.
The attraction of the unlike poles, may be regarded,
then, as a consequence of the attraction of like cur-
rents. For it is found to be universally true, that
6
122 GALVANIC ELECTRICITY.
currents moving in the same general direction, attract
each other, while those moving in opposite directions,
repel.
What is the 290. MUTUAL ACTION OF COIL AND MAG-
mutual action NET — jf a floating magnet be substituted
of a coil and
magnet? for one of the coils, in the above ex-
periment, the result is not in the least affected.
They act toward each other precisely as if both
were magnets, or both, coils.
291. ACTION OF A SINGLE WIRE ON
What is the . ,
action of sin- A COIL.— A single wire, carrying a cur-
yle wire on a rent actg Qn & floatmcr coil in the same
magnetic coil r
manner. Stretched above it, as in-
dicated in the figure, the north pole of the coil
will move to the right. The motion is such as to bring
adjacent currents, in the wire, and in the coil, to co-
incide in direction.
292. POLARITY OF THE COIL IMPARTED
What effect f
has the mag- TO IRON. — A bar of soft iron placed in
neticcoil upon tk Q-i becornes itself a magnet, and re-
metals ?
ceives the name of electro-magnet. Great-
er power is acquired if the metal is, closely
wound with copper wire, covered with cotton3
to prevent any lateral passage of the current.
The horse-shoe shape, in which the poles are
brought round near to each other, is the more
common. The power of such magnets contin-'
tinues only while the current is passing. Electro- p
magnets have been constructed capable of lifting a ton,
or even more. They are sometimes employed in dress-
ing iron ores, to separate, by their attraction, the work-
ELECTRO-MAGNETISM. 123
able ore from the refuse earth with which it is mixed.
A steel bar introduced into the helix while the current
is passing, becomes permanently magnetic. Permanent
magnets, are now commonly made in this manner.
293. PERMANENT MAGNETISM OF STEEL.
What effect
has the mag- It appears, from the last paragraph, that
"ted I™11™1*™ a bar °f S°ft ir011 1S a magnet> as long aS
an electrical current circulates around it.
But the steel, if once magnetic, remains so permanent-
ly. This is accounted for, by supposing that the cur-
rent, in the wire, excites a current in the surface of the
steel itself, which continues to flow, without interrup-
tion, after the wire is removed.
294. ACTION OF A SINGLE WIRE ON
What is the
action of a A MAGNET. ^-A wire, carrying a cur-
t magnet? °* rent in the direction shown in the
figure, acts on a magnet, precisely as
on a floating coil. The north pole of the mag-
net is made to deviate to the east. The mo-
tion is such as to bring adjacent currents in wire
and magnet to coincide.
295. ELECTRICAL THEORY OF MAG-
Explain the .
electrical theo- NETisM. — According to this theory, all mag-
Ttlm?magne' netism? including that of the load-stone,
the magnetic needle, and that of the earth
itself, is a consequence of the circulation of electrical
currents. In the earth, such currents are known to be
excited, and kept in motion, by the sun, heating in turn
successive portions of its surface. They flow from
east to west, making of the earth, as it were, an im-
mense coil, or helix. In magnets they are also in con-
124
GALVANIC ELECTRICITY.
Explain the
figure.
stant circulation, the direction being dependent on the
position in which the magnet is held. In the case of
a magnet whose north pole is directed north, the di-
rection is from west to east across the upper surface,
and of course, in the contrary direction on the under
side. The earth acts on a magnet, or a floating coil,
as one helix acts on another. The north and south
direction of the magnetic needle is a consequence of
this action.
296. THE THEORY ILLUSTRATED. — In
illustration of this theory, let a globe be
coiled with a wire, carrying a current, as indicated in
the figure. Let the current flow from east to west
through the coil. A small magnetic needle placed at
different points on the surface
of the globe, however the po-
sition of the latter may be
changed, will always point to
"its north pole. It is under-
stood, in this experiment, that
the current is strong enough
to overcome the influence of
the earth itself on the mag-
net. A freely movable coil through which a current
was passing, would, in this case also, act precisely like
a magnet.
297. MAGNETIC TELEGRAPH. — The ex-
Explain the . .
principle of planation of the mechanism of the mag-
netic teleg,raPh belongs to Natural Philoso-
phy. The principle of its operation may
MAGNETIC TELEGRAPH. 125
be here given. It has already been stated, that a piece
of soft iron becomes a magnet, when a current of elec-
tricity circulates in a coil surrounding it. Now, sup-
pose the two ends of such a coil, situated in a distant
city, to be made long enough to reach a battery in
the place where the reader resides, and to be stretched
along over posts, and connected with the poles of the
battery. The current occupies no perceptible time in
its passage. Therefore, as soon as the battery is set
in operation, it circulates through the whole extent
of the wire, and, of course, through the coil in the
distant city. The piece of iron which it incloses
is made a magnet, and will immdiately lift its arma-
ture. If the current is stopped, the piece of iron ceases
to be a magnet, and drops its armature. But the
operator at the battery can send or stop the current at
will, by simply disconnecting one of the wires, and
thereby lift or let fall the armature a hundred or a thou-
sand miles off, as often as he pleases. He can have
an understanding, also, with the person in the distant
city, who sees the motion of the armature, as to what
it shall mean. One lift may indicate the letter A ; two
lifts, the letter B ; and so on. So any thing may be
spelled out, and it thus becomes possible to commu-
nicate ideas by electricity. If these lifts of the arma-
ture can be made to record themselves on a slip of
paper, the further advantage of writing at the distant
station is gained. And this is precisely what is realized
in Morse's telegraph, and more particularly described in
all recent works on Natural Philosophy.
126 GALVANIC ELECTRICITY.
298. THE EARTH, USED AS A CONDUCTOR.
What ^s said
of the earth It would seem requisite to extend both ends
as^conduc- of the wire forming the coil through all
the intervening distance, and then to con-
nect them with the opposite poles of the battery ; but
it is found, in practice, that one is sufficient, and that
all the middle portion of the second wire may be dis-
pensed with. The remaining ends, one connected
with the helix, and the other with the battery, being
made to terminate in large plates, and buried in the
ground, the earth between them is found to take the
place of the second wire, and complete the circuit.
Mention some 299. APPLICATIONS OF THE TELEGRAPH.
remarkable There are many applications of the tele-
applications t
of the tele- graph beside the one of transmitting intel-
graph. ligence to distant places. In the city of
Boston, an alarm of fire is instantaneously communi-
cated throughout the city, and the bells rung by tele-
graphic apparatus.
In Marseilles, France, a single clock is made by sim-
ilar means to indicate the time on dials, placed in the
street lamps of the city. Electro-magnetic apparatus
has also been employed with the most remarkable suc-
cess in increasing the dispatch and accuracy of astro-
nomical observations ; making it possible to accomplish
during a single night in the study of the heavens, what
formerly cost a month of labor.
300. PHYSIOLOGICAL EFFECTS OF GAL-
Describe the
physiological VANisM. — The nerves of animals are ex-
fanismf? ff<a' tremel7 susceptible to the galvanic influ-
ence. The apparatus represented in the
PHYSIOLOGICAL EFFECTS. 127
figure, which consists of strips of zinc and copper,
three inches in length, separated by a cork, is sufficient
to produce convulsive twitchings
in the legs of a frog or toad. A
larger apparatus produces more decided effects. The
legs are to be employed, with a portion of the back
bone attached, which is grasped by the sharpened ex-
tremities of the galvanic tweezers. As often as the
circuit is completed, by bringing the other extremeties
into contact, by the pressure of the fingers, the legs
are observed to twitch, as if they were still possessed
of life. The leg of a grasshopper, grasped in its
thickest part, may also be employed in the experiment.
In both these cases, the moisture of the flesh or skin
is the exciting fluid of the galvanic pair. In view of
the destruction of life which they involve, these expe-
riments should be confined to the lecture room, or only
made where many persons are to be instructed by their
exhibition.
301. DISCOVERY OF GALVANISM. — In the
discovery of words of Arago, " this immortal discovery
galvanism g^osQ in the most immediate and direct
made ?
manner, from an indisposition with which
a Bolognese lady was affected, in 1790, for which her
medical adviser prescribed frog broth." The frogs had
been killed and skinned, and were lying on the table
of her husband's laboratory. Experiments were in
progress with an electrical machine, which stood near
tli em, when it was observed that the frogs' legs were
convulsed, as the spark passed. This was not a new
fact, but Galvani was not acquainted with it, and un-
128 GALVANIC ELECTRICITY.
dertook to find out the cause. In preparing for the in-
vestigation, he chanced to hang the hind legs of seve-
ral frogs, by copper hooks, from the iron railing of the
balcony of his window. As often as the wind, or any
accidental cause, brought the muscles into contact with
the iron bar, the legs were convulsively agitated. The
astonishment of the experimenter can scarcely be con-
ceived. In undertaking to account for an old fact, he
had stumbled upon a most important discovery. The
theory which he proposed was not correct, but the re-
sults to which the observation have since led are as-
tounding. The telegraph, the electrotype, and many
metals discovered by galvanic means, may all be re-
garded as its offspring.
302. EXPLANATION. — The convulsion
Explain the
above experi- produced in this case, is entirely analagous,
in its course, to that described in the last
paragraph. The two metals, the moist muscle, and
the wind, to produce contact, and so complete the cir-
cuit, are all the conditions essential to the production
of a current, and consequent contraction of the nerves.
INFLUENCE OF HEAT. 137
magnesia come together, they unite and form sulphate
of magnesia, or epsom salt. But the stimulus of heat
is often required, particularly when the acid, as well
as the oxide, is a solid substance. The affinity be-
tween acids and bases, is in accordance .with the gene-
ral law, that chemical attraction between substances is
strongest, in proportion as they are most unlike, or op-
pos3cl to each other, in their properties.
324. PROPERTIES OF ACIDS AND BASES.
What are the ,
properties of I he properties of these two classes of
acids and ba- compOun(jSj are opposite, and when brought
together, they neutralize each other. Thus,
when acid and soda are brought together, the acid taste
of the former and the alkaline taste of the latter, both
disappear. Acids change certain vegetable blues to
red. Bases restore the color. The experiment may
be made with an infusion of litmus* in water. A leaf
of purple cabbage answers the same purpose. Acids
color it red, while potash, and the alkalies, change
the red to green.
325. EFFECT OF HEAT TO PRODUCE COM-
What is the .
effect of heat BINATION. It IS 86611 from the foregoing,
on chemical ^^ h t j ft essential to chemical
combination ?
combination. This is almost always the
case where both substances are solid. Beside height-
ening their chemical affinity, heat has the effect of
bringing the particles into closer and more general con-
tact, and, within the range of affinity, by the melting
*Litmus is a blue vegetable pigment much used by chemists, for the
purpose mentioned in the text.
138 LAWS OF COMBINATION.
or fusion which it accomplishes. Sulphur and iron, for
example, require the aid of heat to bring about their
union. The sulphur melts, and then combines with
the iron.
326. Further heating, has often just the
Mention an- ~, , ,
other effect of contrary enect. it causes substances al-
heat. ready combined, to separate from each other
again. This is especially the case, when one of
them is a gas. Thus, if oxide of silver or gold is
heated, the oxygen passes off in the gaseous form, and
leaves the metal behind.
327. Heat owes its decomposing effect,
Why does heat . , . _ . ..
have this ef- m this and similar cases, to the tendency
which it imparts to certain substances, to
assume the gaseous form. And as all bodies would,
probably, be gaseous, at a sufficiently high tempera-
ture, sufficient heat would probably decompose all
chemical compounds.
328. EFFECT OF SOLUTION. — The solu-
What is the
effect of solu- tion of one or both of two substances to be
combined, has, in a multitude of cases,
the same effect, in promoting chemical combination,
as that produced by heat. The reason is also the
same. It brings them into more general and thorough
contact. This is illustrated in the case of ordinary soda
powders, the two constituents of which, will not act
on each other, unless one, at least, is dissolved.
329. ELECTRICAL RELATIONS OF ELE-
What are the
electrical rela- MENTs. — 1 he metals are sometimes spoken
°^ as electro~P°sitive an(l tne metalloids as
electro-negative, for reasons given in the
ELECTRICAL RELATIONS. 139
chapter on galvanism. Electricity also resolves salts
into the bases and acids which compose them. The
acid goes to the positive pole, and is, therefore, elec-
tro-negative. The base goes to the negative pole, and
is, therefore, electro-positive.*
* The laws of combination, and other subjects which belong to
chemical philosophy, are further considered in the chapter on Salts,
in the introduction to Organic Chemistry, and in the Appendix. Ad-
ditional remarks on the atomic theory adopted in the text, are also
given in the Appendix.
141
III.
INORGANIC CHEMISTRY.
CHAPTER I.
What is oxy-
gen
METALLOIDS.
OXYGEN.
329. DESCRIPTION. — Oxygen is a trans-
parent and colorless gas, a little heavier than
the atmosphere. It is much the most
abundant substance in nature. One fourth
of the air, one-ninth of the ocean, and, probably, half
of the solid earth, is oxygen.
330 . PREPAR-
ATION. — Gase-
ous oxygen is expelled from
many substances, which
contain it, by the simple
agency of heat, Chlorate
of potassa, and black oxide
of manganese, are such
substances.
Give the com- 331. Mix equal quantities of these ma-
phte process, terials, and heat half a tea-spoonful of the
How is oxygen
prepared ?
142 METALLOIDS.
dry mixture in a test-tube, connected, air-tight, with two
clay pipes, as represented in the figure. The connec-
tions are made by winding the pipe-stems with strips
of wet paper, folded in such a manner that the stopper
thus formed tapers slightly toward the end. The first
portions of gas, which contain an admixture of the air of
the tube, are allowed to bubble through the water, and
escape. The rest is made to rise into a half-pint vial,
which it gradually fills, by displacing the water. The
vial has previously been filled with water, then
covered with a bit of glass, inverted in the wa-
ter. If it is desired to hang it on the side of the
bowl, a hook is then introduced, made of strong,
doubled wire, the two parts being kept about half
an inch apart, and the vial is then hung, by its help, on
the side of the bowl ; or this may be dispensed with,
and the vial held by the hand in its proper place, while
the gas is collected. When the process is completed,
vial and hook, if the latter has been used, are to be low-
ered into the bowl, the mouth being carefully kept
below the surface ; the hook is then removed, the mouth
covered with a bit of glass, and the vial then inverted
upon a plate containing a little water, and so kept until
it is wanted for an experiment. All other gases, that
are not absorbed by water, may be collected in the
same manner.
Explain the 332. EXPLANATION. — Although black
process. oxide of manganese may be employed as
a source of oxygen, it does not yield this gas at the
temperature employed in the above experiment. But,
OXYGEN. 143
for reasons not well understood, the admixture of this
or any other infusible powder, facilitates the evolution
of this gas from the chlorate. At a red heat, part of
the double portion of oxygen which the black oxide
contains is expelled in a gaseous form.
332. A SIMPLER METHOD. — The above
Give a, simpler
method of pre- method, for preparing oxygen, is here
paring oxygen ^^ becauge it iUustrates the mode of
collection of gases in large
quantities, and makes its
accumulation visible to the
eye. The oxygen needed
for the following experi-
ments will be more con-
veniently prepared by pla-
cing the mouth of the test-tube, containing the proper
materials, in a wide-mouthed vial, and heating, as be-
fore. As the gas is evolved, it will expel the air, and
soon fill the vial.
333. IRON BURNED IN OXYGEN. — Make
How cm iron
be burned in a coil of very fine iron wire, by winding
the latter around a pencil ; fasten one end
into the middle of a cork, by slitting the lat-
ter, and attach a fine splinter to the other end.
Light the splinter, and introduce it into a vial
of oxygen. The wire itself will take fire,
and burn with brilliant scintillations. In this
and the following experiments, the cork is to
be placed loosely over the mouth of the vial, to pre-
vent its violent expulsion by the heated gas.
144 METALLOIDS.
334. EXPLANATION.— In this experiment
What takes . , . . . -
place in the the oxygen in the vial unites with the
"nenir^™' *r°n °^ tn6 WirG' and becomes soli(i, in
the form of oxide of iron. The oxide
fuses into a small globule on the end of the wire, and
occasionally falls, and melts its way into the glass.
This is apt to be the case, even when water is left in
the bottom, so that a vial is likely to be destroyed by
this experiment. The process is exactly the reverse of
that which takes place when binoxide of manganese is
heated, to produce oxygen. In the one case, oxygen
was driven from the metal ; in the other, it is drawn
to it, though not in the same proportion.
335. TAPER REKINDLED IN OXYGEN. —
Describe the
taper experi- Introduce a newly extinguished taper, or
shaving, which has a little fire on the wick,
into a vial of oxygen. It will be immediately rekin-
dled. This experiment may be many times repeated
without a new supply of gas.
336. Combustion is more vivid in
Explain t/te
last experi- pure oxygen, than in air, because the latter
is diluted with other gases, which do not
take part in the combustion.
337. COMBUSTION OF PHOSPHORUS. —
Describe the .
experiment Place a piece of phosphorus, of the
with phosphor gize of a pea? on a piece of chdkj
slightly hollowed out for the pur-
pose, and connected with a cork by a fine
wire. Ignite the phosphorus, and introduce
it immediately into a bottle of oxygen. It
OXYGEN. 145
will burn with the utmost brilliancy, producing a light
which the eye can scarcely bear.
338. The white fumes which fill the
VFha t acid re-
sults from this bottle in this experiment, are composed of
experiment? particies of phosphoric acid, which are
produced by the union of the phosphorus and oxy-
gen. They collect on the sides of the vial, and soon
dissolve in water, which they absorb from the air.
The water will be found to possess a sour taste, and
to redden blue litmus paper, which is a characteristic
of acids.
339. COMBUSTION OF CHARCOAL. — At-
Descnbe the
experiment tach a small piece of charcoal to
with charcoal? & fine wire, ignite Qne end of ^
thoroughly, and introduce it into a vial of ox-
ygen, having a cork at the other end, as
before. It burns with brilliant sparks. A piece
of charcoal bark is best adapted to this pur-
pose.
340. Carbonic acid is formed in the
What is pro-
duced in this above experiment, from the union of
experiment ? carbon with oxygen. It is a gaseous acid,
and cannot be seen. Neither can it be detected by
its taste. But a piece of moistened litmus paper, held
for some time in the bottle, will be reddened by it, and
proof of the presence of an acid may be thus obtained.
When wood burns, it also yields carbonic acid.
341. DEFINITION OF COMBUSTION. — All
Dciine com- /. ,, , . /.
bustion. °f tne above experiments are cases of
combustion, and combustion may be den-
ned as combination of any two substances, attended by
7
146 METALLOIDS.
light and heat. Metals which will not burn in the
air, because it is diluted oxygen, burn brilliantly, as
has been seen, in pure oxygen.
342. PREVIOUS HEAT REQUIRED. — In or-
Why is heat _ _
required to der that most substances may burn, they
Uon/°mbHS' must first be heated> to increase their affin-
ity for oxygen. Take carbon, as an exam-
ple. Before heating, its affinity for oxygen is not suf-
ficient to bring about the requisite combustion. In this
condition it may, therefore, lie for any length of time,
in the air, or oxygen gas, without uniting with it.
But heat stimulates the tendency to combination, and
the bit of charcoal previously ignited, goes on burning,
until it is consumed. The first particles obtain the
necessary stimulus of heat, from the previous igni-
tion, the next from the burning of the first, and so on.
343. UNCOMBINED OXYGEN REQUISITE. — •
What kind of __ '.
oxygen is re- Mere presence of oxygen is not sufficient
amlnrtion? for. combustion. It must be free, or un-
combined oxygen. After burning char-
choal in oxygen gas, the vial contains just as much
oxygen as before, but being already combined, it has
no affinity, or appetite, for more carbon, and there-
fore will not produce a new combustion.
344. EACH PARTICLE IN TURN MUST BE,
If each parti-
cle is not heat- HEATED. — If the first particles that com-
bme' do llot communicate sufficient heat
to the next, then the combustion stops.
This may be illustrated by lighting a tightly wound
roll of paper, and holding the flame upward. It is
soon extinguished, because the heat that is produced
OXYGEN. 147
by the combustion of one portion of the paper, is not
communicated to the next, but passes off into the air.
But if the taper be held with the flame downward,
each particle in turn receives the stimulus of heat ne-
cessary to combination, and the whole is consumed.
345. DECAY OF LEAVES AND WOOD. —
What causes
the decay of The decay of leaves and wood, is a sort
of slow combustion, but not sufficiently
vigorous to produce light and heat. In this case, as in
the ordinary combustion of wood or coal, the particles
which have combined with oxygen, pass off into the
air, in an invisible form.
346. BLEACHING. — Bleaching may also
How may . *
bleaching be be regarded as a kind of slow combustion.
On exposing cloth to sun and air, its color-
ing matter is gradually burned up, by the atmospheric
oxygen.
347. OXYGEN A PURVEYOR TOR PLANTS.
oxygen\» a° ^ nas been seen that both in combustion
purveyor for an(j decaVj the oxygen of the air combines
with the particles of leaves, and wood, and
coal, and passes off with them in an invisible form. It
flies off with them into the air, and yields them again
to living plants, to produce new leaves and flowers, and
fruits. Indeed, they are entirely dependent, for their
support, on what they thus obtain from the death and
decay of their predecessors, through the agency of this
ever active purveyor, the oxygen of the air. But for
the fact that the particles of vegetable and animal mat-
ter, can thus be used again and again, the supply would
148 METALLOIDS.
soon be exhausted, and vegetation cease upon the face
of the earth.
348. OZONE. — By passing an electrical
How is °*°ne current, continually, through oxygen gas,
for some time, it becomes mysteriously
changed in its proportions. In this changed condition
it is called ozone. It is, as it were, intensified in its affin-
ities by the current, so that like chlorine, it will attack
silver, and exhibit many other of the properties of the
latter gas. The electricity of the air has similar effects
on the oxygen which it contains, and, in consequence of
its varying electrical condition, the proportion of ozone
is, also, from time to time, extremely varied. There is
reason to believe that this substance has important influ-
ence upon health, and that either its deficiency or excess,
is injurious. In cholera seasons, it has been observed
to be present in comparatively small quantity, while,
during the prevalence of a species of influenza called
" grippe," it is said to be more abundant. These obser-
vations need confirmation, by further experiments, before
the facts can be regarded as fully established. The pres-
ence of ozone, is indicated by the discoloration, through
the influence of a current of air, of a test paper, de-
scribed in the section on chlorides.
Tir, 349. RELATIONS TO LIFE. — Oxygen is
What relation
to life does ox- as essential to life, as it is to combustion.
ygen sustain! The ^^ oxygen of the ^ ig better
adapted to breathing, than pure air, but that which con-
tains much less than its due proportion, is no longer
fitted to support life. Respiration consumes oxygen, so
that the air of a close room is constantly being depri-
CHLORINE. 149
ved of this essential constituent, without obtaining any
new supply. As a consequence, it soon becomes unfit
to breathe. The case is similar to that of a taper
burned in a bottle. The oxygen of the air in the bot-
tle, is gradually consumed, and the flame grows grad-
ually more and more dim, till it goes out. So life grows
fainter and fainter, in a close, unventilated room.
What is said 350. Oxygen has been used, with great
of oxygen as success, as a means of resuscitation, in cases
a means of '
resuscitation ? of suffocatio.ii and drowning, when similar
use of air was without effect. In such cases, it is forced
into the lungs through a tube, from a jar or bladder.
CHLORINE.
What is chlo- 351. DESCRIPTION. — Chlorine is a yel-
TwLreisit lowish green gas, of peculiar odor, about
found"! %\ times as heavy as the air. More than
one half of common salt is chlorine. Salt mines and
the ocean, therefore, contain it in immense quantities.
352. PREPARATION. — Chlo-
How is chlo-
rineprepar- nne is prepared from muriat-
ic acid, which is composed of,
chlorine and hydrogen, by using some
agent to retain the latter, and liberate the
former. Black oxide of manganese is1
such a substance.
Give the com- 353. The oxide is well covered with mu-
picte proceeds. rjatic acid, and kept warm, as the evolution
of the gas proceeds. This is best effected by a cup of
hot water, as represented in the figure. Chlorine gas
soon displaces the air in the second vial. It should be
corked as soon as filled.
150 METALLOIDS.
Explain the 354. It will be remembered that black
process. oxide of manganese, is a substance con-
taining a double portion of oxygen, part of which
is feebly held, and very willing to go. Its use in
making chlorine, depends on this fact. The loosely
held oxygen, seizes upon the hydrogen of the muri-
atic acid, remaining with it as water, and at the same
time setting its chlorine at liberty.
355. A SIMPLER METHOD. — Acids expel
Describe an- . - , , . , ,
other method chlorine from many bases which have
of preparing previously been made to absorb it.
chlorine f
Lime is one of these bases. Bring
into a wide-mouthed, half-pint vial, a table
spoonful of dilute sulphuric acid, and add
rather more than the same bulk of chlo-
ride of lime, or bleaching powder. It is best
to add it in small portions, covering the vial
with a cork or bit of glass, after each addition.
The vial will soon be filled with faintly green chlorine
gas. More of the materials will be required, if the
chloride of lime is deteriorated by exposure to the air,
as is often the case. The gas thus produced, may be
used for most of the experiments which follow, with-
out transferring it to another vessel.
356. CHLORINE, HEAVIER THAN
that chlorine AIR. — This is already imperfectly
lhan *a£f Proved; in the first method of col-
lecting chlorine, but the follow-
ing proof is more satisfactory. The gas pro-
duced in the last experiment, may be slowly
poured 'from the vessel containing it, into
CHLORINE. 151
another wide-mouthed vial. The second vial, if
the smaller of the two, may be thus filled without re-
ceiving any acid from the first. In small quantities
the gas cannot be seen to flow, but will actually pass
from one vessel into the other. Its presence may be
proved by the methods given in the following experi-
ments.
357. CHLORINE DISSOLVES IN WATER. —
that chlorine Having filled a vial with chlorine, by the
"
first of the methods above described, cork it,
and open it under water, contained in a
bowl. As the gas dissolves in the water,
the latter will rise to take its place. When
it has risen a little way, cork, and shake
the vial, and open it again below the
surface. The water will then rise and
dissolve still more of this gas. The so-
lution is to be set aside for a subsequent experiment.
Gas produced by the second method above described,
may also be used in this experiment, if previously
transferred to another vial.
358. ACTION OF CHLORINE ON METALS.
Describe the
action of chlo- Chlorine gas combines with many metals,
rine on metals. convertmg tnem into chlorides. Their ac-
tion may be illustrated by sprinkling, finely pulverized
antimony, into a bottle of chlorine. Each particle of
metal ignites as it falls through the gas, and a minia-
ture shower of fire is thus produced. The white smoke
which is produced in this experiment, is composed of
minute particles of chloride of antimony.
152 METALLOIDS.
359. NASCENT CHLORINE. — Nascent chlo-
What ts the .
action of nas- rme, in its action on the metals, is the most
cent chlorine* powerful agent known. Even the noble
metals yield to its power, and waste away in the liquid
which contains it. The term nascent signifies being
born, or in the act of formation.
What is the 360< A11 §ases are most energetic, in
general fact their action at the first moment of their
in relation to .
nascent bo- separation from compounds which contain
them, and while they may be regarded as
still retaining the solid form themselves. The subse-
quent expansion into the gaseous form, diminishes their
energy.
36.1. Nascent chlorine is best obtained
How is nas- .. , * i • • i • i i i /» .
cent chlorine by mixing hydrochloric acid with half its
best obtained? bujk of strong nitr[c aci(j. guch a mix_
ture is called aqua regia. The latter acid compels the
former to yield a constant supply of its own chlorine in
the nascent condition. It does this, by means of its oxy-
gen, which seizes upon the hydrogen of the hydrochlo-
rine acid, forming water, and sets its chlorine at liberty.
The remnant of the nitric acid escapes, as in the case
of its action on metals hereafter described.
362. CHLORINE DECOMPOSES WATER. —
Does chlorine .
decompose wa- 11 chlorine water be exposed to the sun
for some days, it loses its green color.
The chlorine combines with the hy-
drogen of the water, forming hydro-
chloric acid, and sets its oxygen at
liberty. If the experiment be made in
a bottle, inverted in water, so that the
CHLORINE. 153
oxygen may collect, bubbles of this gas will be found
above the liquid. This experiment proves the pow-
erful affinity of chlorine for hydrogen.
363. BLEACHING BY CHLORINE. — Intro-
How is calico _
bleached by duce bits of calico into the solution 01
chlorine ? chlorine before obtained. Most colors will
soon disappear. If the solution is weak, the bleaching
effect will be better shown, with infusion of litmus or
red cabbage. Color may also be removed from cloth
or paper by hanging the article to be bleached, pre-
viously moistened with water, in a vial of gaseous
chlorine.
364. Chlorine water may be prepared
How ts chlo-
rine water best in larger quantity, by leading the gas di-
preparcd? rectiy jnto water. The first of the two
methods before described, will be found the most ad-
vantageous.
365. OXYGEN THE REAL BLEACHING
Explain how
chlorine AGENT. — The real bleaching agent in this
bleaches. method of bleaching, is the same as that
mentioned in paragraph 346. It is oxygen, always
present during the process, as an element of the water
which moistens the material. The chlorine simply
acts to bring nascent oxygen into activity. It does
this by depriving it of the hydrogen with which
it is combined. The oxygen having thus lost its com-
panion, looks about, as it were, for something else
with which to combine. The coloring matter of the
cloth being the first thing at hand, is destroyed by the
extreme energy of its affinity.
7*
METALLOIDS.
366. ACTION OF NASCENT OXYGEN. — The
Show the ad-
vantage of superior force of an element in its nascent
nascent oxy- con(jition js strikingly shewn in the above
experiment. A piece of calico, hung
in a bottle of oxygen gas, would not lose its color.
But the nascent oxygen which chlorine liberates, be-
gins to destroy the coloring matter on the first instant
of its liberation.
367. CHLORINE AND TURPENTINE. — Im-
JJescnoe the
inflaming of merse a rag wet with camphene or spirits
of turpentine in a vial of chlorine
gas. It is immediately inflamed,
with the production of dense black smoke.
Spirits of turpentine is composed of hydro-
gen and carbon. The former combines
energetically with chlorine, as to produce
flame in the above experiment, while the latter
is separated in the form of black particles, which con-
stitute the smoke.
368. USE AS A DISINFECTANT. — As chlo-
Is chlorine a
disinfectant ? rine destroys color, when used as a bleach-
ing agent, so it destroys noxious vapors in
the air. Its minute atoms fly forth like birds of prey,
seizing on the impurities of the atmosphere, and de-
vouring them. Chloride of lime is commonly substi-
tuted for chlorine for this use. A little of this salt is
placed in a saucer, and moistened, when it gradually
yields chlorine through the action of the carbonic acid
of the air. Stronger acids evolve it abundantly.
CHLORINE. 155
369. CHLORINE A DESTRUCTIVE AGENT.
What is said . .
of chlorine as Chlorine, as has been seen, is one of the
a destructive mogt destructive of all substances. It not
agent £
only destroys colors and odors, but any
kind of vegetable or animal matter, long submitted to
its action, wastes away, and is destroyed. It does this
partly by its own direct action, and partly by letting
loose the atoms of nascent oxygen, as before described.
370. IN WHAT SENSE DESTRUCTIVE. It
In what sense
is it destruct- is always to be borne in mind that the
term destruction is used in chemistry in an
entirely figurative sense. Thus, neither oxygen nor
chlorine, strictly speaking, destroy. They only com-
bine with the particles of the substances they seem to
destroy, forming new, and often invisible compounds.
Many of these will be hereafter mentioned.
371. RELATIONS TO ANIMAL LIFE. — Chlo-
G-ive the rcla- . .
tions of Mo- rine is a poisonous gas. No danger, how-
rmcto animal ever? ig to be apprehended from the escape
of small portions into the air, during the
preceding experiments. The diluted gas, however, is
apt to produce irritation of the throat, and consequent
coughing,
In what re- 372. RESEMBLANCE TO OXYGEN. In
chTorinTre many respects chlorine is similar to oxy-
semble oxy- gen, as has already been shown. It com-
bines with almost all of the elements, and
with many compounds. This combination is often
attended with light and heat, and is therefore com-
bustion. The metal antimony, for example, as has
166 METTALLOIDS.
already been shown, will burn, in chlorine gas, even
without kindling.
Mention some 373. COMPOUNDS OF CHLORINE AND OXY-
compounds of GEN — Chlorine combines with five atoms
chlorine and
oxygen- of oxygen to form chloric acid. This acid
is of importance, principally, as a constituent of the
chlorate of potash, to be hereafter mentioned in con-
nection with Nitrates. Hypoclorous acid a constitu-
ent of bleaching powders is another compound of chlo-
rine with oxygen. It is again mentioned in the section
on Chlorides.
IODINE.
v/
374. DESCRIPTION. — Iodine is commonly
dine? WJiere seen in the form of brilliant blue-black
is it found? scales, somewhat similar to plumbago in
appearance. In odor it resembles chlorine. It is found
in the water of the ocean, in sea-weeds, sponges, &c.,
but always in combination with sodium, or some
other metal. Minute traces of it are found to exist in
the atmosphere, and thence are transferred to the bodies
of animals.
375. PREPARATION. — For the preparation
Explain the . .
manufacture oi iodine, a lye
of iodine? made fj.om the
ashes of certain sea-weeds,
is heated with oil of vitriol
and black oxide of manga-
nese. The liberated oxy-
gen of the latter expels va-
IODINE. 157
pors of iodine from the mixture. These being led into
a receiver, crystallize in brilliant scales. A retort and
receiver are commonly used in the process. The ashes
of sea- weed, employed for the purpose, are called kelp,
and are prepared in great quantities on the coast of
Scotland.
VIOLET VAPORS or IODINE.
violetlapors Introduce a few scales of iodine into
of iodine pro- a test-tube or vial, and heat it for
duced?
a moment over the spirit lamp. The
solid iodine is immediately converted into a
beautiful violet vapor, which fills the vial. As
the latter cools, the iodine becomes again solid,
in the form of minute crystals. On warming
these crystals, thejeolbr re-appears.
^^077. COLORING EFFECT ON STARCH. -
Describe the jjeat a |juie iO(Jme in a ^ive
effect produ-
ced by iodine stem, and as soon as vapors ap-
°paste?C pear, blow them against a sheet
of paper, covered with figures
made with thin starch paste. The iodine vapor imme-
diately colors them blue. The paste may be made in
a test-tube, over a spirit lamp.
378. ENGRAVINGS COPIED BY IODINE.- —
How are en-
gravings copi- A transient copy of an engraving, or other
ed by iodine ? prmtecj matter, may be made, by exposing
it to faint fumes of iodine, and then pressing it down
upon paper moistened with vinegar, or dilute nitric
acid. The vapors, adhere to the ink only, and are
transferred by pressure ; producing, with the starch
contained in ordinary letter paper, a blue impression.
158 METTALLOIDS.
BROMIDE.
379. Bromine is a dense reddish-brown
of bromine? fluid, exhaling at ordinary temperatures, a
deep orange-colored vapor. It is similar, in
its chemical properties, to chlorine, but the latter is
the stronger of the two, and expels bromine from its
compounds. Thus, if chlorine be passed into one end
of a heated tube containing bromide of silver, the va-
pors of bromine will be seen to pass out at the other
end, and escape, while the chlorine remains, and takes
possession of the metal. Bromine, like chlorine, is
found in sea- water, and in the water of mineral springs,
combined with sodium, or some other metal. The
power of chlorine to expel it from its compounds, is
made use of in manufacturing bromine. This sub-
stance is used in photography, but is otherwise of little
general interest. Although widely distributed, it ex-
ists in nature, in comparatively small quantities. Bro-
mine vapors have the effect of imparting to starch a
beautiful orange color.
FLUORINE.
'^What is said 380. Fluorine is yellowish-brown gas,
of fluorine? Of strong odor, somewhat similar to that of
chlorine. It is one of the elements of the beautiful
mineral, fluor spar. It is prepared from the fluoride of
potassium, by means of the galvanic current. Its isola-
tion has been attended with great difficulties, and the
SULPHUR. 159
gas is therefore imperfectly known. Its principal com-
pounds, are hydrofluoric acid, and fluor spar, to be here-
after described.*
S.ULPHUR.
381. DESCRIPTION. — Sulphur is a brittle
W/iatissul-
phur? Where yellow solid, burning with a peculiar odor,
it occur? ma(je familiar in the ignition of common
friction matches. With the metals, it forms sulphides
or sulphurets. In Sicily, and certain other volcanic
regions, it occurs in beautiful, yellow crystals. Gyp-
sum, and iron pyrites, or fools gold, represent the two
principal classes of minerals that contain it. It also
enters in small proportion into the composition of all
animal and vegetable substances. It is the sulphur in
eggs that blackens the silver spoon with which they are
eaten.
382. PREPARATION. — In preparing com-
Describe the
manufacture mercial sulphur, the impure material of
of suphur ? voicanic regions, is highly heated, and thus
made to fly off as vapor, leaving its earthy impurities
behind. The vapors are condensed as flowers of
sulphur. The process by which a solid is thus vap-
orized, and re-converted into a solid, is called sublima-
tion. Native sulphur may also be partially purified by
simple fusion. Its earthy impurities having settled,
it is poured off into moulds, and thus converted into
roll brimstone.
* Many compounds of chlorine, bromine, iodine and fluorine, with
each other and with oxygen, are known to the chemist,/but they are
without interest to the general student
V
160 METTALLOIDS.
383. SUBLIMATION OF SULPHUR. —
SlZlf The sublimation of sulphur may be
of sulphur be shown by heating a small bit of the \
shown ?
substance in a test-tube. Flowers
of sulphur will deposit in the upper portion of
the tube.
384. COMBUSTION OF SULPHUR.-
What is said ,__ . .
of the com- Melt some flowers of sulphur upon
^afphur°{ the 6nd °f a wire wound with
thread, and hang them after ignition in a
vial of oxygen gas. The oxygen gas com-
bines with the sulphur, forming a new com-
pound gas, called sulphurous acid. A bril-
liant blue flame accompanies the combina-
tion. It thus appears that acids may be gase-
ous, as well as liquid. The acidity may be
proved, as usual, by blue litmus paper.
385. BLEACHING BY SULPHUR. — Intro-
Descnbe the
process of duce a red rose, or other flower, into a vial
mTansnofbL. filled with sulphurous acid. It will soon
phur ? lose its color. Wash it with dilute sulphu-
ric acid, and the color re-appears This experiment
may also be made in a bottle, in which sulphur has
been burned in common air.
386. EXPLANATION. — Sulphurous acid
Why docs sul- -, • , , , ,
phurous acid lorms a white compound with the red color-
bieach? -ng matter Of the rose ft mav seem incom-
prehensible, that a colorless gas, and red coloring
matter should unite to form white, and it would be
so, were the case one of mere mixture. But it is an
SULPHUR. 161
instance of chemical combination, in which as is often
the case the properties of the constituents entirely /dis-
appear. When sulphuric acid is afterward used, the co-
lor re-appears, because the stronger acid has expelled
the weaker, and has itself no inclination to form with
the coloring matter a similar combination.
387. STRAW BLEACHING. — The bleach-
proccL If ie m£ °f straw goods is always effected by
straw bleach- sulphurous acid. They are first moistened,
and then exposed to the fumes of burning
sulphur. An inverted barrel is often made to serve
the purpose of a bleaching chamber. Articles thus
bleached by sulphurous acid, after a time, regain their
color. This is not the case in chlorine bleaching, be-
cause the coloring matter is not merely changed, but
destroyed. The agent is not applicable to straw, on
account of a faint brown tinge which it imparts to the
material.
388. COPYING MEDAL-
? LIONS. — Sulphur melts,
medallions by readily, by application of
sulphur? *\ , :*.
heat. At a higher temper-
ature, it thickens again. Still further
heating, makes it again fluid. In
this second period of fluidity, it has the remarkable
property of assuming a waxy consistence, on being
poured into water. In this condition, it is used for
copying seals, coins, and medals. The copy acquires,
in a few hours, the original hardness of sulphur. The
plastic material may be obtained in the form of elastic
162 METTALLOIDS.
strings, by pouring molten sulphur from a test-tube,
into cold water.
389. SULPHUR CRYSTALS. — Sulphur may
How may crys-
talsof sul- be obtained in a crystalline form, by melt-
*tained?° *n£ ^ *n a P^P6 bowl, at a gentle heat, and
then allowing it to cool. A crust
soon forms on the top, which is broken, and a
portion of the liquid sulphur below, poured out.
On breaking the pipe, it. is found filled with crystals,
shooting across the interior, from the encrusted walls.
SULPHURIC ACID.
Describe sul- 390. DESCRIPTION. — Sulphuric acid is a
phuric acid. colorless, oily fluid, of intensely acid taste,
known in commerce as oil of vitriol. It is composed
of sulphur and oxygen, in the proportion of one atom
of the former, to three of the latter. It also contains
Water, with which it is chemically combined. As
it is among the most important of all chemical
products, the process of its manufacture will be given
with some detail.
391. PREPARATION. — Sulphuric acid may
How may sul- . .
phuric acid be be made directly, from its elements, by ig-
prepai nithig a mixture of air and vapor of sul-
phur, with a red-hot 'iron. In quantity, it is always
made from sulphurous acid, by imparting to the latter
additional oxygen. Take a bottle in which sulphur
has been burned, and which, therefore, contains sulphur-
ous acid, and hold in it, for a short time, a rod or stick
,„.
SULPHURIC ACID. 163
moistened with nitric acid. The gaseous sulphurous
acid obtains oxygen from the nitric acid, which is rich
in this element, and very liberal of it, and thereby be-
comes sulphuric acid. A little water, previously placed
in the bottom of the vial, absorbs the acid
thus formed. To acidify the water to any
considerable extent, it will be necessary to
burn sulphur, and introduce the moistened rod
repeatedly. That the acid is not the sulphu-
rous or the nitric acid, employed in the pro-
cess, may be proved by using it to make hy-
drogen gas.
392. REMARK. — The red fumes which
What causes .
the red fumes nil the vial m the last experiment, consist
of the changed nitric acid, (nitric oxide,)
which has just given up part of its oxy-
gen, and is now resuming part of it from the air. It
thereby becomes a third substance, of a red color, to
be again mentioned in the section on nitric acid.
393. MANUFACTURE OF OIL OF VITRIOL.
Explain how .
sulphuric acid — The method of the production of oil
lurcd™^™ °^ vitri°l on a large scale, is essentially the
same as that above given. Fumes of
burning sulphur, and vapor of nitric acid, with air and
steam, are introduced into a leaden chamber, when the
process proceeds, as before described.
394. Comparatively little nitric acid is
Why is but
little nitric needed in the process, for it is found that
acid required wnjje ft y^ids oxygen to the sulphurous
fumes, the changed acid greedily seizes oxygen from
the air of the chamber, arid imparts it again, to keep up
164 METALLOIDS.
the process. The air is, therefore, the real oxidizer,
while the changed nitric acid only acts to transfer it
to the sulphurous fumes.
Describe the 395. DESCRIPTION OF ACID CHAMBERS.
acid chambers, rpne fjgure represents one form of the
leaden chambers
employed in the
above manufac-
ture. Connect-
ed with them
are a steam boiler and two furnaces, in one of which
sulphur is burned, and converted into sulphurous acid.
Over the sulphur is another vessel, containing the
materials for making nitric acid, the formation of which
commences as soon as the sulphur flame has imparted
the requisite heat. The vapors thus produced, are
mingled with air and steam in the leaden chamber.
How they act together to produce sulphuric acid, has
been already explained. The space is divided by a
partition, in order that all the materials may be more
thoroughly mixed, as they pass through the narrow
opening below it. The acid, as it forms, dissolves in
water which covers the bottom of the chamber, and is
thus collected. Lead is used as a lining for the cham-
bers, because the acid woul-d destroy almost any other
material that might be employed.
396. The dilute acid obtained from the
How is the
chamber acid chambers, is concentrated first in leaden
concentrated? vessels? and afterward) when it hag become
strong enough to corrode the lead, in retorts of platinum.
The metal platinum, being of about half the value of
SULPHURIC ACID. 165
gold, the vessels in which the evaporation is carried
on, are extremely expensive. Some manufactories de-
liver tens of thousands of pounds of sulphuric acid per
day.
397. COMPARATIVE STRENGTH OF SUL-
Hov) is the
strength of PHURIC ACID. — SulphUHC acid JS the
Sshmvn?iC °cid strongest of a11 acids- This ma7 be shown
by bringing it to a direct 'trial of strength
with other strong acids. If poured, for example, on
nitrate of potassa, which is, as its name implies, a com-
pound of nitric acid and potassa, it takes sole possession
of the base, and expels the nitric acid in the form of
vapor. It expels muriatic acid from its compounds in
the same manner. This is the method by which nitric
and muriatic acids are always obtained. Whatever
they can accomplish when free, may therefore be
traced back to the power of sulphuric acid, which gave
them their liberty. The latter is the king among the
acids, who accomplishes indirectly, what he cannot ef-
fect in person. The solution of the noble metals by
aqua regia is one among these indirect results.
398. Sulphuric acid is volatile at high
Is it strongest
at high tenipe- temperatures. Phosphoric, and other non-
volatile acids, are, therefore, under certain
circumstances, superior to it. This is illustrated in cer-
tain crucible operations, where compounds containing
sulphuric acid are heated with such acids. The sul-
phuric acid is then easily dispossessed, and compelled
to take refuge in flight.
What is the 399. ACTION OF SULPHURIC ACID ON
action of sul- METALS.— Sulphuric acid attacks all metals,
jjliunc acid
on metals. with the exception of platinum and gold.
166 METALLOIDS.
Even the dilute acid acts on all the metals hereafter
named, as far as manganese.
400. The action of the dilute acid may
Illustrate the . .
action of the be illustrated, by placing a few bits of zinc
dilute acid. in a tumbler? with a iittie waterj and ad-
ding a small portion of oil of vitriol. The metal dis-
solves with the evolution of hydrogen gas. The rea-
son of the evolution of this gas has been already
given.
401. The action of the strong acid may
Illustrate the J
action of the be illustrated, by heating a little copper,
strong acid. w{ih Q[{ of vitriol> in a test-tube. The
metal dissolves with the evolution of sulphurous acid
fumes. The reason of the appearance of sulphurous
acid will be given in the next section.
402. AFFINITY FOR WATER. — The affin-
liffinlt °*ofwl- ity °f sulphuric acid for water is so strong
phurtc add that it lays hold on every particle of the
for water? . / f ,
invisible aqueous vapor of the atmosphere.
It finds it, in what seems the driest air ; and every par-
ticle which it catches, it retains. It grows in bulk
by what it thus drinks, as will be seen if a little oil of
vitriol is left exposed to the air, for a few days, in an
open vessel. It is sometimes necessary, in chemical
operations, to free gases from all the aqueous vapor
which is mixed with them. This is done completely,
by causing them to bubble through oil of vitriol, and
again collecting them.
403. HEAT BY DILUTION. — When sul-
What takes .
place whensui- phuric acid and water are mixed, conden-
U sati°n ta^es place, accompanied by eleva-
tion of temperature. Fiftv cubic inches of
SULPHUROUS ACID. 167
sulphuric acid, and fifty cubic inches of water, when
mixed, do not fill a vessel of the capacity of one hun-
dred cubic inches, but fall about three inches short.
Condensation has, therefore, taken place to the amount
of three inches. Heat is, as it were, pressed out in
such cases, as explained in the early part of this work.
404. WOOD CHARRED BY SULPHURIC
Why does sul-
phuric acid ACID. — Wood dipped in oil of vitriol is
soon charred. Wood is composed of car-
bon, hydrogen, and oxygen. The last two together
form water. The affinity of sulphuric acid for water has
been mentioned above. The acid and the wood being
in contact, it would seem that the hydrogen and the
oxygen of the latter agree to combine and satisfy this
demand. The carbon being at the same time isolated,
appears in its natural black color. Sulphuric acid ex-
erts a similar action on other vegetable substances.
405. IMPORTANT USES. — Sulphuric acid
What are the .
uses of sul- is largely employed for dissolving indigo,
pkuric add? for use in dyeing and calico printing . aiso?
for converting common salt into sulphate of soda, as a
preparatory step to the manufacture of carbonate of
soda. It is also essential in the manufacture of super-
phosphate of lime, an article now so extensively used
in agriculture. Nitric and muriatic acids are pro-
duced through its agency from nitre and common
salt.
SULPHUROUS ACID.
What is sul- 406. DESCRIPTION. — Sulphurous acid is
phurous acid? a gaSj having the smell of a burning match.
168
METALLOIDS.
It is composed of sulphur and oxygen, in the proportion
of one atom of the former to two of the latter. The ter-
mination " ous" indicates, as in other cases, a smaller
proportion of oxygen than is contained in some other
acid composed of the same elements.
407. PREPARATION. — It has already been
How is sul-
phurous acid shown that this acid may be prepared, by
prepared? burning sulphur in oxygen. Another, and
better method, is to heat, oil of vitriol, with bits of cop-
per. The oil of vitriol is thus
deprived of part of its oxygen,
and converted into sulphurous
acid. The process may be con-
ducted in a test-tube. By lead-
ing the gas through a smaller
tube, into a vial partly filled with
water, a solution of sulphurous
acid may be obtained, possessed of the same bleaching
and other properties as the gas itself. When the evolu-
tion of the gas commences, the heat of the lamp is no
longer required.
Explain the 408. EXPLANATION. — Copper has a very
process. strong affinity for oxygen, and takes it
from the oil of vitriol, which possesses it in large pro-
portion. The oil of vitriol, thus deprived of part of
its oxygen, is converted into sulphurous acid gas.
409. USE IN PRESERVING WINES. Slll-
W ny ^.? sul-
phurous acid phurous acid, in small quantities, is some-
7eTtowlnesd? times added to wine> to prevent its sour-
ing. This change is owing to the absorp-
tion of oxygen from the air. Sulphurous acid is a
NITROGEN. 169
substance possessed of an excessive appetite, or affinity,
for oxygen. A small portion of it in a wine cask, will
seize on what little oxygen finds admission, and so
prevent the deterioration of the wine. It destroys it-
self in this act of protection, and is converted into sul-
puric acid.
How is sul- ^®' ^SE 1N SUGAR MANUFACTURING.
phurous acid The oxygen of the air so modifies the
employed in . . ~ ,, .. . . , ,
manufactur- juice of the sugar-cane, that it cannot be
ing sugar ? made to yield its due proportion of sugar.
Sulphurous acid, by appropriating the oxygen to itself,
prevents this effect, and is said to double the product.
It is generally used in the form of its lime compound,
called sulphite of lime. The objection to its use con-
sists in the slight sulphurous taste which it imparts to
the sugar. But this is said to be removed by clarifi-
cation, at a loss of ten per cent., leaving still a large
gain from the employment of the process. The bleach-
ing effects of sulphurous acid have already been illus-
trated.
NITROGEN.
411. DESCRIPTION. — Nitrogen is a trans-
trogen ? parent gas, without taste or odor. It forms
Where is it about four_fifths of the air we breathe. It
found ?
occurs also in combination with other ele-
ments in a solid form. One-fifth of the weight of the
dried flesh of animals is nitrogen. It also enters into
the composition of nitre and other salts.
170 METALLOIDS.
Howisnitro- ^- PREPARATION.— Nitrogen is pre-
gen prepared? pared from ordinary air by removing its
oxygen. For this purpose a small portion of phospho-
rus is floated on a slice of cork upon water, and then
kindled, and a vial inverted over it.
As it burns, it abstracts the oxygen ;
the water rises to take its place, and
what is left of the air is nitrogen.
The cork should be a little hol-
lowed out, and chalk scraped into
the cavity. Water must be poured into the saucer as
the first portion rises into the bottle. The bottle is
then cooled, either by water or long standing, and
co-rked while yet inverted It is then shaken, to wash
the gas. A piece of phosphorus, of the size of a large
pea, is sufficient for the preparation of half a pint of
gas.
Explain the 413. EXPLANATION. — The burning phos-
process. phorus selects all of the oxygen atoms in
the air, and, by combining with them, converts them
into solid particles of a certain oxide of phosphorus,
called phosphoric acid. These particles at first ap-
pear as a white smoke, and are afterward dissolved in
the water.
414. NITROGEN EXTINGUISHES FLAME. — If
Does nitrogen
extinguish a burning taper be lowered into the bottle of
flame? y. njtrOgenj as above prepared, it will be im-
mediately extinguished. Flame is the brightness which
accompanies active chemical combination, but here is
nothing to combine. Nitrogen is a sloth among the
elements, possessing no degree of chemical activity.
THE ATMOSPHERE. 171
415. PRINCIPAL OFFICE OF NITROGEN.—-
What is the
principal of- The principal office of the nitrogen of the
ficeofnitro- air is to dilute its oxygen. The latter, if
pure, would soon consume our bodies, as
it hastens the combustion of a taper, or other combus-
tible.
416. THE ATMOSPHERE. — The air we
What is the
composition breathe, and which, to the depth of fifty
of the air? miles or more; forms the crystal shell, or
envelope of the globe we inhabit, is a mixture of nitro-
gen and oxygen gases, with aqueous vapor. It also
contains small and varying proportions of carbonic acid,
and ammonia.
417. PROOF THAT AIR is A MIXTURE. —
How is it
proved to be a That it is a mixture, and not a chemical
compound, is sufficiently evident from the
fact that it possesses no new and peculiar properties
different from those of its constituents. It is further
proved to be a mixture, from the fact that heat, which
is the usual attendant on chemical combination, is never
occasioned when air is artificially produced by the ad-
mixture of its constituents.
yse 418. USE OF CARBONIC ACID AND AMMONIA
served by IN THE AIR — Carbonic acid and ammonia.
its carbonic
acid and aw although present in the air in extremely
small quantity, subserve the most impor-
tant purposes in administering to the growth of plants.
They constitute the gaseous food of all forms of vege-
table life, as will be more fully explained in succeeding
chapters of this work.
172 METALLOIDS.
419. ANALYSIS OF THE AIR. — The me-
proportion of thod bY which the relative amount of ox-
nitrogen deter- ygen and nitrogen in the air is determined
has been already given. On burning phos-
phorus under a glass jar, as there described, the water
is found to rise and fill a
little more than one-fifth of
the vessel, thereby indica-
ting that one-fifth of the
air which it contained was
oxygen gas. The remaining fths is nearly all nitro-
gen. In accurate experiments, a graduated tube is
employed, instead of a jar or tumbler. It is not es-
sential that the phosphorus should be ignited. With-
out ignition, it will gradually combine with all the
oxygen, and remove it from the air contained in the
tube.
420. In order to determine the amount
How is the . .
amount of car- of aqueous vapor and carbonic acid in the
atmosphere, a gallon, or other measured
nia deter- quantity of air, is drawn through tubes
containing materials to absorb these sub-
stances. This quantity is known by the increased
weight of the tubes after the experiment is completed.
421. THE APPARATUS DESCRIBED. — The
Describe the . f.
apparatus apparatus used in the experiment is repre-
wfedinthis sented in the last figure. It consists of a
analysis. °
bottle, or small cask, filled with water, and
provided with a cock below. The cock is turned, and
as the water no ws out, air flows in through the tube to
take its place. The quantity of air that has passed
NITRIC ACID. 173
through the tubes is known by the quantity of water
that has flowed out from the cask. The materials em-
ployed in the tubes are pumice stone drenched with oil
of vitriol, in the first, to absorb the water ; and caus-
tic potassa, in the second, to retain the carbonic acid.
The method for determining the amount of ammonia
in the atmosphere is essentially the same, muriatic acid
being used as the absorbant.
422. PROPORTIONAL COMPOSITION OF
What are the
proportions of THE AIR. — The proportions of the four
fousfttwnteof constituents of the air above mentioned,
the atmo- as obtained by the method just described,
are, about 21 per cent, of oxygen, 79 of
nitrogen, arWth of carbonic acid, and t?4fofc¥rvtb of
ammonia. The proportion of aqueous vapor is ex-
tremely variable. That of carbonic acid and ammo-
nia is also variable to a considerable extent.
NITRIC ACID.
What is nitric 423. DESCRIPTION. — Nitric acid is a thin.
acid? colorless, and intensely acid fluid. It cor-
rodes metals instantaneously, with the evolution of deep
red vapor. It is composed of nitrogen and oxygen, in
the proportion of one atom of the former to five of the
latter. It contains, in addition, water, with which it
is chemically combined. It is possible to make it an-
hydrous, or free from water, but such an acid is never
used.
How is nitric 424. PREPARATION. — Nitric acid exists
add prepared? m a dormant state in ordinary saltpetre.
174 METALLOIDS.
Its affinities being entirely satisfied by the potassa with
which it is combined in that substance, it lies there per-
fectly inactive. Sulphuric acid being stronger, has the
power of taking its base,
and expelling the acid in
the form of vapor. In or-
der to collect and condense
the acid fumes, the mixture
may be made in a test-tube,
the mouth of which opens
into a vial or flask. It is necessary to keep the vial
covered with porous paper or cloth, and to moisten it
frequently in order to maintain its coolness. Wher e
larger quantities are prepared, a retort and well-cooled
receiver are employed, as represented in the Appendix.
425. OXIDATION OF METALS. — If a little
What effect
has nitric acid nitric acid is poured upon a copper coin,
placed in a capsule or saucer, the coin will
immediately begin to dissolve. It is not, strictly
speaking, the metal which dissolves. One portion
of the acid first converts the metal into oxide, by giving
it part of its own oxygen. It thereby destroys itself,
while another portion of undecomposed acid dissolves
the oxide which is formed. One portion, in reality,
sacrifices itself to satisfy the appetite of the other. Most
other metals are similarly acted on by nitric acid.
What is nitric 426. NITRIC OXIDE.* — The vapors which
oxide? are gjven off m the jast experiment are
* It will be observed that the term oxide is sometimes applied to
compounds of the metalloids with oxygen. (See chap, iii., Inorg.
Chem.)
NITRIC ACID. 175
nitric oxide, changed by the air into which they rise.
The nitric oxide is, so to speak, the fragment of nitric
acid, which is left after three atoms of its oxygen are
abstracted. Rising into the air, it combines with oxy-
gen enough partly to supply the place of that it has
just lost, and is thus converted into red fumes of per-
oxide of nitrogen, containing four atoms of oxygen.
This compound is also called hyponitric acid. Still
another compound of nitrogen with oxygen is de-
scribed in the section on nitrates.
427. Repeat the experiment of the last
JJeecrioe ano- . •>--,•
ther method of paragraph, placing the coin and acid in a
rlddfum/s Ule sma11 vial or test-tube> instead of a saucer,
and collect the nitric oxide produced, as
shown in the figure. The collec-
tion should not be commenced
until a colorless gas is produced.
It will be best to fill the vial
to only two-thirds of its capa-
city. Then lift it from the
bowl, and let the remaining water run out. The air
will immediately rush in, and change the colorless ni-
tric oxide to red vapors of the peroxide of nitrogen.
How does ni- 428. OXIDATION WITHOUT SOLUTION.
tnc acid act Nitric acid oxidizes tin and antimony, but
on tin { J '
does not dissolve them. The experiment
will be best made with tin-foil. After the action of
the acid, it will be found converted into a white pow-
der. Gold and platinum are neither dissolved nor ox-
idized by nitric acid.
176
METALLOIDS.
429. COMBUSTION BY NITRIC ACID. — As
How may com-
bustion be nitric acid contains much oxygen, combus-
effectedby ni- j. jon ^y fa means would seem to be a
probable result. To
prove that it has this effect, boil
strong nitric acid in a test-tube,
the mouth of which is filled with
hair. As the vapors pass through
they will cause it to smoke, and,
if the acid is sufficiently strong,
produce ignition.
430. COMBUSTION OF
Describe the .
experiment Phosphorus is readily
withphospho- ignited by throwing it
upon nitric acid. If
the acid is not very strong, it must be previously
heated. Particles of phosphorus, scarcely larger than
mustard seed, should be used in this experiment.
PHOSPHORUS.-
Whatisphos
phorus ?
Where does i
occur?
phosphate
portion.
flow is it pre-
pared ?
PHOSPHORUS.
431. DESCRIPTION. — Phosphorus is a
wax-like, and nearly colorless, solid, read-
t ily ignited by heat or friction.*1 It forms
part of the mineral apatite, which is a
of lime. Bones also contain it in large pro-
It is never found umcombined.
432. PREPARATION. — Phosphorus is
made from bones. These are composed,
* When phosphorus is cut, it should always be under water, and
every particle not used should be immediately returned to a bottle
containing water.
PHOSPHORUS. 177
principally, of gelatine and phosphate of lime. The
individual constituents are gelatine, lime, oxygen, and
phosphorus. To obtain the phosphorus, all the rest
are to be first removed. Fire removes the gelatine,
oil of vitriol the lime, and charcoal, the oxygen.
Give the com- 433. The bones, having been previously
piete process, burned, the ground ash is mixed with di-
lute sulphuric acid and water, and, after several hours,
filtered. Sulphuric acid unites with the lime, forming
an insoluble sulphate, and at the same time sets the
phosphoric acid at liberty, The solution containing
phosphoric acid is then mixed with
charcoal, and heated in an earthen
or iron retort. The carbon takes the
oxygen, and passes out of the retort with it,
as gaseous carbonic oxide. The phosphorus which is
left, being vaporized by the heat, is also expelled, but
is reconverted into solid phosphorus by the cold water
into which it passes. The figure will give some idea
of the arrangement. The neck of the earthen retort
passes into a copper tube, which leads into water. The
gas produced by the process bubbles through the water
and escapes, while the phosphorus is hardened by it,
and remains. The mass thus obtained is melted under
water, and run into moulds.
434. PHOSPHORESCENCE. — This term is
phorescence°?~ applied to the luminous appearance of sea-
water when agitated, and to other faint
light, unaccompanied by perceptible heat. It is ob-
served when an ordinary friction match is rubbed upon
the hand in the dark. The light is owing to a slow
8*
178 METALLOIDS.
combustion of phosphorous, which takes place without
kindling. The product of the combustion, is a white
powder, called phosphorous acid, which soon becomes
liquid, by absorbing moisture from the air.
435. A HARMLESS FIRE. — By agitating
How may a .
harmless fire phosphorus with ether, a small portion of
be produced 9 the former substance is dissolved. This
solution, if rubbed upon the face and hands, makes
them luminous, in the dark. This is another case of
phosphorescence. A piece of phosphorous of the
size of a pea is amply sufficient for the experiment.
436. COMBUSTION UNDER WATER. — Phos-
How may
phosphorus be phorus may be burned under water, by the
^te??™*** helP of substances ricn in oxygen. Chlo-
rate of potassa is such a substance. Place
a few scales of this salt, and a bit of phospho-
rous of the size of a pea, at the bottom of a
wine glass previously filled with water. Par-
tially fill the bowl of a pipe with oil of vitriol,
and drop it in small portions on the mixture,
bringing the pipe stem, each time, close to the bottom
of the glass. As soon as the stronger acid is applied,
chloric acid, containing much oxygen, is liberated and
decomposed, and the phosphorus inflamed. A similar
combustion of phosphorus, by means of nitric acid,
has already been described.
437. FRICTION MATCHES. — Ordinary
What is said
of friction phosphorus is too inflammable to be em-
ployed in the manufacture of friction match-
es. By heating it under carbonic acid for a long time, it
becomes changed in color, and also less fusible and in-
ARSENIC. 179
flammable. In this form of red phosphorus, it is used
in the manufacture of friction matches.
ARSENIC.
438. DESCRIPTION. — Arsenic is a grey
Why is arsen- /• • .
ic introduced substance, of metallic lustre, and for this
metalloids? reason, commonly classed among the met-
als. On the other hand, in view of the
compounds which it forms, and especially in view of
the fact that its oxygen compounds are acids, and not
oxides, it is more properly classed among the metal-
loids. Its analogies to phosphorus are most striking,
and it is for this reason here introduced, in immediate
connection with that element.
In what re • 439. ANALOGIES TO PHOSPHORUS. Ar-
spccts do pkos- sem'c unites with oxygen in the same pro-
phorus and . J ...
arsenic resem- portions as phosphorus, forming similar
acids. These in turn form salts resembling
each other most perfectly, in external appearance and
in crystalline form. It also combines with three atoms
of hydrogen, to form arseniuretted hydrogen, a gas
analogous to phosphuretted hydrogen, to be hereafter
described. Of the two principal oxygen compounds of
phosphorus, the higher, or phosphoric acid, is the more
important, and was therefore more particularly consid-
ered. On the other hand, the lower orarsenious acid, is
the more important of the acids of arsenic.
How is arsenic 440. PREPARATION. — Metallic arsenic is
prepared ? found native. It may also be prepared
180 METALLOIDS.
from arsenious acid, by heating with a
large proportion of carbon, as in the
Case of phosphorus, before described.
Beside mixing with carbon, it is best,
also, to cover with the same material,
and heat from above, downwards. The metal passes
off as vapor, and condenses in the cooler part of the
tube, or other vessel in which the experiment is per-
formed, as a steel grey incrustation.
ARSENIOUS ACID.
441. RATSBANE. — The ordinary white
What are the , J
properties of arsenic of the shops, also known as rats-
arscnious bane, is a white and nearly insoluble sub-
stance, possessed of a slightly sweetish
taste. It is not properly arsenic, but arsenious acid. It
contains three atoms of oxygen, to one of metal. Al-
though sweet, it is called an acid, because it possesses
the chemical characteristic of an acid, viz : the ca-
pacity of uniting with bases to form salts.
Howisitpre- 442. PREPARATION. — Arsenious acid is
pared? prepared from metallic sulphurets, many of
which contain a certain proportion of arsenic, by
roasting in the air, and thus burning out their arsenic, in
the form of arsenious acid. The fumes are condensed
in high chimneys, from which the incrustation of the
solid acid is afterward removed. Mispickel, which is
a double sulphuret of iron and arsenic, and certain
ores of nickel and cobalt, are much employed for the
production of arsenious acid.
ARSENIC. 181
„„ 443. POISONOUS PROPERTIES OF ARSENIC.
What is said
of arsenic as White arsenic or arsenious acid is a fearful
a poison? poison, and more frequently employed than
any other substance, for the destruction of life. But
its detection, and the entire demonstration of its pres-
ence in the body, after death, or in materials which
have previously been ejected from the stomach, is cer-
tain.
444. No one but a professional chemist
What is said
of its detec- should undertake such an investigation,
tijon ? involving, as it does, the issues of life and
death. No one else, indeed, can, be qualified to guard,
with certainty, against the presence of arsenic in the
chemicals which are used in the process, or in other res-
pects, to bring the inquiry to that point of absolute de-
monstration, which is always required in judicial inves-
tigations. But the methods of detection, being simple,
and a subject of interesting and instructive experiment
to the student, will be briefly described in the paragraphs
which follow. Many other compounds of arsenic, be-
side arsenious acid, are highly poisonous.
How arsenic i* ^45. DETECTION OF ARSENIC. If a few
detected? drops of a solution of chloride of arsenic*
be added to the liquid from which hydrogen is being
evolved from a vial, by the ordinary process, the
nascent hydrogen decomposes the chloride of arsenic
and carries off the metal, in the form of a gas. On sub-
sequently kindling the hydrogen jet, and bringing
* Such a solution is prepared, by dissolving white arsenic in hydro-
chloric acid.
182 METALLOIDS.
down upon it a cold white surface, like that of
a plate or saucer, the metal is again given up,
and reveals itself as a brownish black and high-
ly lustrous stain. The process may be con-
ducted in an ordinary vial, to which a pipe
stem, or glass tube has been fitted, by the
method before described. The above method
of detection is called Marsh's test. In a case of
suspected murder by poison, the moment of the in-
troduction of the pure porcelain into the flame, be-
comes one of the most intense interest. The gather-
ing stain, is at once the emblem of guilt and sentence
of ignominious death.
446. EXPLANATION. — The decomposi-
Sxplainthe tjon Of arsenious ac{d by hydrogen, in the
above process. J J
above experiment, and the reason of the
deposition of the metallic mirror, still remains to be ex-
plained. The nascent hydrogen affects the decompo-
sition of the acid, by a double action ; on the one hand
uniting with the metal to form arseniuretted hydrogen,
which escapes, and on the other hand, with its chlorine
to form hydrochloric acid, which remains behind. The
mirror of metal is deposited upon the plate or saucer,
because the introduction of the cold body into the
flame, so lowers its temperature that the metal itself can-
not burn. If the jet of gas is left to burn without in-
terference, both of its constituents are consumed to-
gether, and the flame assumes a blue color, from the
presence of the arsenic.
ARSENIC. 183
How are ar- ' DISTINCTION BETWEEN ARSENIC AND
tenicandan- ANTIMONY STAINS. — If in testing for arsen-
Smguish™ ic> by the method above described, a metallic
cd- spot is obtained, the evidence of the pres-
ence of arsenic is not entirely conclusive. A solution
of antimony, if substituted for arsenic in the experi-
ment, will give rise to the production of somewhat sim-
ilar stains. But the experimenter will find, on com-
paring the two kinds of spots, that they are of quite
different appearance. Those of antimony are of deep-
er black, and fainter lustre. Again, those of arsenic
are much more readily removed by heat. " Chloride of
soda," is a still more conclusive means of distinguish-
ing them. A solution of this substance will dissolve
the arsenic stains, while it leaves those of antimony
unaffected. The " chloride of soda," to be used in
the experiment, is prepared by adding an excess of car-
bonate of soda, to a solution of " chloride of lime,"
and then filtering the liquid.
448. ADDITIONAL TESTS FOR ARSENIC. —
Mention some . .. ,
additional A second test has already been given in
l^tcs/or arse' the paragraph on the preparation of me-
tallic arsenic, to which the student is re-
ferred. The formation of a yellow precipitate, on the
addition of hydro-sulphuric acid to a solution, also
renders it highly probable that arsenic is present.
If on drying the precipitate, and heating it with a
mixture of cyanide of potassium and carbonate of soda,
a metallic mirror is obtained, the inference of the pres-
ence of arsenic is confirmed. The process is to be
conducted as directed in paragraph 440. In this exper-
184
METALLOIDS.
iment, the cyanide of potassium has the effect of retain-
ing the sulphur, while it allows the volatile arsenic to
pass and deposit above.
449. Still another evidence of the pres-
What is said
of the garlic ence of arsenic, is afforded in the charac-
teristic garlic odor which is emitted by the
flame produced by burning arsenic, in the experi-
ment previously described, called Marsh's test. The
same odor is also obtained on sprinkling a little ar-
senious acid upon burning charcoal.
Mention the 450. PREPARATIONS FOR THE ARSENIC
preparations TEST> — Before proceeding with the che-
for the ar-
senic test? mical experiments for the detection of ar-
senic, some preliminary labor is com-
monly required, to bring the material to
be tested into proper form. It com-
monly consists of matters which have
been ejected from the stomach, or of the
contents of the stomach itself. If the
student wishes to begin at this point, in his experi-
ments, he may add a small portion of arsenic to
some bread and water, and proceed with this paste, in
his investigation. This mixture is to be diluted with
water, and saturated with chlorine, as in the process for
preparing a solution of this gas. Chlorine has the effect
of destroying a certain portion of the organic matter,
and rendering the rest floculent, so that the liquid may
be easily separated from it by filtration. It also brings
the arsenic perfectly into solution, as a chloride. This
solution is then filtered, and treated as directed in the
preceding paragraphs.
CARBON. 185
What is the ^^* ANTIDOTE TO ARSENIC. The hy-
antidotefor drated sesquoxide of iron is regarded as
the best antidote to arsenic. (See Oxides.)
Its action depends on the formation of a compound,
with the poison in the stomach, which is insoluble,
and therefore inactive. Milk, sugar, and white of eggs,
are also given with advantage, as in most other cases
of poisoning.
452. ARSENIC EATERS OF AUSTRIA. —
What is said _ . . ., .
of the arsenic In the mountainous portions of Austria,
triar?°^AuS~ bordering on Hungary, the peasantry are
„ given to the strange habit of eating arse-
nic. It is said to impart a fresh, healthy appearance to
the skin, and also to make respiration freer when as-
cending mountains. Those who indulge in its use
commence with half a grain, and gradually increase
the dose to four grains. If this habit is regularly in-
dulged, its injurious effects are said to be long retarded.
But as soon as the dose is suspended, the symptoms of
poisoning by arsenic immediately manifest themselves.
CARBON.
453. DESCRIPTION. — Carbon in the form
Describe the .
different of coal, is a black, brittle, solid. As
forms of car- piumDago, and coke, it is grey, with me-
tallic lustre ; as the diamond, it is trans-
parent, and the hardest of known substan-
ces. Plumbago is commonly called black
lead, but it contains no lead whatever. The
figure in the margin represents the more
common crystalline form of the diamond.
186 METALLOIDS.
454. OCCURRENCE. — In the form of bi-
carbon occur? tuminous and anthracite coals, carbon ex-
ists in immense quantities, buried in the
earth, in various countries ; as graphite, or plumbago,
it is also quite a common mineral ; as the diamond, it
is the rarest of all gems. It is one of the elements in
limestones, marbles and chalk, which are all carbonate
of lime. It forms nearly one half of all dried veget-
able matter, and more than half of all dried animal
matter. One two-thousandth of the air, also, is car-
bonic acid, of which carbon is a constituent.
455. CHARCOAL.— The
Illustrate the
preparation preparation of charcoal, one
of charcoal. Qf the forms Qf carboilj may
be illustrated by heating a small por-
tion of wood or cork, in a test-tube.
The other constituents of the wood,
and part of the carbon, are converted
into water, gases, and tan, and the larg-
est part of the carbon ramains behind, in the form of
charcoal.
456. PREPARATION. — In quantity, it is
coal made? commonly made by burning wood in large
heaps, previously covered with earth and
sod. It is necessary to admit a little air, through open-
ings in the heap, to maintain a partial combustion.
If too much air is admitted, the wood is entirely
consumed, and no charcoal is produced. Coke is
made from bituminous coal, by a similar process, and
is also obtained as a residue in the manufacture of
coal gas.
CARBON. 187
457. LAMP BLACK. — Lamp black, still an-
other form of carbon, is made by conducting
the smoke of rosiri into chambers, construct-
ed for the purpose. It consists of unburned particles of
carbon. It is used, extensively, in making paint.
Bone black is made by heating bones in closed vessels.
It is a sort of charcoal produced from the gelatine of
the bones.
458. PURIFYING PROPERTIES OF CHAR-
Dcscribe the
purifying COAL. — Charcoal absorbs gases, and retains
ZtoalS°f them iri its Pores' in lar§e qualities.
Tainted meat, and musty grain, intimately
mixed with it, become sweet. The charcoal has re-
moved the unpleasant gases, proceeding from them.
The absorbent power of charcoal may be illustrated,
by holding a paper moistened with ammonia, in a vial,
until the air within it has acquired a strong ammo-
niacal odor. On afterward introducing some pow-
dered charcoal, and shaking the vial, the odor will be
removed.
459. PRESERVATIVE PROPERTIES OF
Illustrate the , ,
preservative CHARCOAL. — Charcoal may be used as a
properties of preventive, as well as a corrective of de-
charcoal f
cay. Posts, if charred at the bottom, be-
fore they are set, are rendered more durable. Water
will keep longer in charred vessels than in those which
have not thus been prepared. The decay of meats and
vegetables is retarded by packing them in charcoal.
Charcoal is itself, one of the most unchangeable of sub-
stances. Wheat and rye charred at Herculaneum 1800
years ago, still retain their perfect shape.
188 METALLOIDS.
460. DECOLORIZING EFFECTS OF CHAR-
Describe its
decolorizing COAL. — Charcoal has, also, the effect of
power. removing coloring matters, and
bitter and astringent flavors from liquids.
Thus, ale and porter lose both color and fla-
vor by being filtered through sugar. Sugar
refiners take advantage of this property, in
decolorizing their brown syrups. Animal
charcoal, or bone black, is best adapted to these uses.
As an illustration of the decolorizing effect of char-
coal, let water colored with a few drops of ink, be
filtered through bone black. The color will be found to
disappear, in the process.
461. COMBUSTION OF CARBON. — All of
of the <y**- tne forms of Carbon are combustible. The
bustionof combustion of charcoal, in air, is a famil-
carbon ?
iar fact. Its combustion in oxygen has
has been already shown. The diamond, and
plumbago, will also burn in a vial of oxygen
gas, if first intensely heated. The product of
their combustion, is precisely the same as that
of charcoal. From the carbonic acid, which
is produced in the combustion, the carbon
may be obtained in the form of lamp black. The
nature of the diamond is thus conclusively established.
462. REDUCTION OF ORES BY CHARCOAL.
How does
charcoal re- The affinity of carbon for oxygen, at a
duce metals? high temperature, is very intense. It de-
prives most ores of their oxygen, and converts them
into metals. An agent which thus produces metals
from their compounds, is called a reducing agent, and
CARBONIC ACID. 189
the process is called reduction. Gaseous carbonic ox-
ide, has the same effect as carbon, because the affinity
of its carbon for oxygen, is only partially satisfied. In
the process of reduction, these reducing agents are them-
selves converted into carbonic acid, by the oxygen with
which they combine. Hydrogen gas, in consequence of
its strong affinity for oxygen, is also a powerful reducing
agent. The reducing power of carbon may be illus-
trated by sprinkling a little litharge on ignited charcoal,
and blowing upon it at the same time, to maintain its
heat. The litharge, or oxide of lead, will thus be par-
tially converted into globules of metal.
CARBONIC ACID.
463. DESCRIPTION. — Carbonic acid is a
What ts car-
bonic acid? colorless gas, without much taste or smell,
eS l an(^ ab°ut one and a nalf times as heavy as
air. Other properties are illustrated in the
experiments which follow. This gas is found in many
mineral waters, and frequently escapes from fissures in
the earth. It is a constituent of all limestones and
and shells, forms ^^Vo- part of the atmosphere. It is
exhaled from the lungs of all animals, and is a product
of the combustion of coal and wood.
464. PREPARATION. — Carbonic acid may
How is carbo-
nic addpre- be prepared by burning charcoal in oxygen
pa1 gas, as directed in paragraph 461. Or it
may be made by hanging a lighted candle, as long as it
will burn, in a bottle filled with ordinary air. In this
190 METALLOIDS.
case, the carbon of the candle is converted into car-
bonic acid, by the oxygen of the air. But neither
of these methods give the unmixed gas, and that which
follows is therefore to be preferred.
465. ANOTHER METHOD. — Pour a tea-
Give the sec- • . .
ond method of spoonful of muriatic acid into a large-
prfpanng it, mouthed half-pint vial, and then
ad i bits of marble, chalk, or carbonate of
soda, until effervescence ceases. The vial
will then be filled with carbonic acid.
Explain the 466. EXPLANATION. Chalk
above process. an(j marble are both carbonate of lime.
As soon as they are dropped into muriatic acid, this
stronger acid combines with the lime, and retains it,
setting the carbonic acid at liberty in the form of a gas.
The gas as it accumulates, expels the air from the vial,
and completely fills it. It is obvious that in this method
we do not make carbonic acid, but use that which na-
ture has already made for us, and imprisoned in the
marble.
467. For most of the experiments that
Describe ano-
ther method of follow, the second simple method of col-
preparation. \eci{on js sufficient, and the gas need not
be transferred to another vessel. When
it is desired to obtain it separate from the
materials from which it is produced, the
apparatus represented in the figure may
be employed.
468. CARBONATED WATERS.
How are car-
bonatcd waters Water absorbs its own volume of carbonic
made l acid, and thereby acquires an acid taste.
CARBONIC ACID. 191
The so called " soda water," or " mineral water," is
prepared by confining water in a strong metallic ves-
sel, and forcing into it gaseous carbonic acid, by means
of a forcing-pump. The increased quantity which it
is thus made to absorb is in precise proportion to the
pressure employed. Neither of the above names give
a correct notion of the nature of the ef-
fervescent drink referred to. It is sim-
ply carbonated water, to which soda is
sometimes added.
469. The absorption of carbonic acid
by water may be shown, like that of
chlorine, by the method illustrated in
the figure. It may also be shown by pouring a gill
of water into a half-pint vial of carbonic acid, and
then shaking it. The palm of the hand being pressed
closely upon the mouth of the vial, the flesh will be
more or less drawn in, to take the place of the gas ab-
sorbed. The vial maybe supported by this attach-
ment.
470. EFFERVESCENT DRINKS. — Cham-
What is said
of effervescing pagne, sparkling beer, and mead, congress
water, and similar drinks, owe their effer-
vescent qualities to this gas held in solution. On expo-
sure to the air, the gas gradually escapes, and the liquids
become insipid to the taste. The air enters and takes
its place, expelling sixty or seventy times its own vol-
ume of gas. This effect may be hastened by striking,
with the hollowed palm of the hand, upon the top of
a glass partly filled with one of these liquids ; there-
by compressing the air, and forcing it to enter rapidly.
192
METALLOIDS.
The carbonic acid immediately escapes with renewed
and rapid effervescence.
471. FLAME EXTINGUISHED
What effect
lias carbonic BY CARBONIC ACID. - Lower a
acid onflame? lighted taperj candle, or splinter
of wood into a vial of carbonic acid, pre-
pared as before directed. The flame will
be immediately extinguished, as if it had
been dipped in water.
Give another ^^' ®* ^ Sam<3 6XPermient mav
method of per- performed by pouring the
££M §as into a vial- at the bot-
torn of which is a bit of
lighted candle. Nothing will be seen
to flow from one vessel into the other,
but the effect will be the same as before.
473. CARBONIC ACID is
Of what use
to plants is FOOD FOR PLANTS. — Carbonic
carbonic acid? ^^ ig Qne Q£ the principal
elements of the food of plants. The leaves absorb
it from the air, and the roots from the earth, and
convert it into wood and fruit. The subject is fur-
ther considered in the latter part of this work.
474. IT is POISON FOR ANIMALS. — Wa-
ter impregnated with carbonic acid is a
healthful drink ; but the same gas, when
taken into the lungs, produces death. It
operates negatively, by excluding the air, and also
positively, as a poison. Being heavier than the air,
lakes of this gas sometimes collect in the bottom of
caverns. There is a grotto of this kind in Italy, called
What is the
effect of car-
b
CARBONIC ACID. 193
the Grotto del Cane, or dog's grotto. A man walking
into it, is safe, but his dog, whose head is below the
surface of the gaseous lake, is immediately suffocated.
Baths of carbonic acid have recently been employed,
with advantage, in the treatment of rheumatism, and
other similar affections, and in cases of enfeebled
vision.
475. How REMOVED FROM WELLS. — Car-
bonicacid re- bonic acid often collects in the bottom of
we^s; an(l occasions danger, and some-
times death, to workmen employed in
cleaning them. A candle previously lowered into the
well will, indicate the danger, if it exist. The flame
will burn less brilliantly, or be entirely extinguished,
if much of the gas is present. By repeatedly lower-
ing pans of recently heated charcoal into the well, and
drawing them up again, the gas will be absorbed and
removed. The charcoal is first heated, to increase its
absorbing power. In this condition it absorbs thirty-
five times its own bulk of gas.
476. CHARCOAL FIRES IN CLOSE ROOMS.
now does
burning char- Fatal accidents not unfrequently occur
To? accidents? from innalmg the fumes of charcoal, burned
in close unventilated rooms. These fumes
consist of mingled carbonic acid and carbonic oxide.
The latter gas will be hereafter described.
477. SOLIDIFICATION OF CARBONIC ACID.
How may car- r^ f •> . .
bonic acid be One oi the most interesting of all chemical
solidified? experiments, is the solidification of car-
bonic acid. By combined cold and pres'sure, this trans-
parent gas, which, under ordinary circumstances, is so
9
194 METALLOIDS.
thin that the hand, passed through it, does not recog-
nize its presence, can be converted into a solid snow.
This is done by bringing into a strong iron cylinder,
connected by a tube with a second similar receptacle,
the material for making more of the gas than there is
room for in the two vessels. The cylinders being
closed, and the gas produced by the agitation of the
materials, it is evident -that they must burst, or the
gas must pack itself away in some more condensed
form. The second vessel is surrounded by ice, and
kept extremely cold, during the process. In this colder
vessel, the gas assumes a liquid form. Being removed
in this condition, one portion of the liquid evaporates
so rapidly as to freeze the rest. An explosive expan-
sion of the liquid into gas would naturally be antici-
pated, but this does not occur. The materials used
in the process are sulphuric acid and carbonate of soda.
478. CARBONIC OXIDE. — When carbonic
How is car- • -i • •
bonic oxide acid is passed through hot coals, it loses
half of its oxygen, and becomes carbonic
oxide. This takes place in coal fires. The coal in
the lower part of the grate, where air is plenty,
receives its full supply of oxygen, and becomes car-
bonic acid. The hot coals above, where the supply
of air is limited, take half of the oxygen from the
carbonic acid, and reduce it to this oxide, convert-
ing themselves partially into carbonic oxide at the
same time. The new gas passes on to the top of the
fire, and there, where air is again abundant, it burns
with a blue flame, and reconverts itself into carbonic
acid. This gas is much more poisonous than carbonic
CARBONIC OXIDE. 195
acid, and is one source of the danger which arises from
open fires in close rooms. One-two-hundredth of it
makes the air, if inhaled for any considerable time, a
fatal poison.
479. COMBUSTION OF CARBONIC OXIDE.
How is car-
ionic oxide For small experiments, the gas is best pre-
best prepared? ^^ by coyermg ft half tea-spOOnful of
oxalic acid* with oil of vitriol, and heating them to-
gether in a test-tube. The gas, on
being kindled at the mouth of the
tube, burns with a beautiful blue
flame. The experiment is re-ndered
more striking, by producing a jet, as
represented in the figure. The gas
thus obtained is really a mixture of
carbonic oxide with carbonic acid,
but the admixture does not mate-
rially affect the experiment.
480. EXPLANATION. — Each molecule of
Explain the .
formation of oxalic acid contains carbon, oxygen, and
carbonic oxide. hydrogerij in the proportion to form one
molecule each, of water, carbonic oxide, and carbonic
acid. Through the agency of sulphuric acid, this de-
composition is accomplished. The water remains with
the acid while the gases are evolved.
481. IT PRODUCES METALS FROM OXIDES.
effect on me- With the help of a high temperature, car-
talhc oxides? bonjc ox[^e takes oxygen from oxides,
and converts them into metals. It contains oxygen
* This acid has the appearance of a salt, and is poisonous.
196 METALLOIDS.
already, but its chemical appetite is only half satisfied
with that element. It is this gas, produced in the fire,
as before described, which converts iron ores into metal,
in the smelting furnace. It is itself converted into car-
bonic acid at the same time.
SILICON.
What is sili- 482. DESCRIPTION. — Silicon is a dark
con ? gray substance, possessed of metallic lustre,
but classed with the metalloids, because it resembles
them in its compounds. It is also called silicium.
It is prepared from silica, by the method hereafter de-
scribed for the production of calcium from lime.
483. SILICIC ACID OR SILICA. — Quartz
*icaf ^ Sll~ or roc^ crvstalj is nearly pure silica. Sea-
sand, opal, jasper, agate, cornelian, and
chalcedony, are other forms of the same substance.
It forms also part of a very abundant class of rocks, called
silicates, and probably forms one-sixth of the mass of
the earth.
484. SOLUBLE SILICA. — Silica may be
How can silica
be made solu- • dissolved in water, by first fusing it with
a large proportion of potash. On then ad-
ding acid, to neutralize the potash, the silica precipitates
in the form a jelly. By this circuitous process, the
most gritty sand is converted into a soft jelly. A sin-
gular application of this rock-jelly, in the adulteration
of butter, has recently been detected in England. Dis-
solved silica also occurs in nature, and hardens into
agates, onyx, and other precious stones.
BORON. 197
485. PETRIFACTIONS. — As wood wastes
What is the
cause of pet- away in certain sihcious waters, the par-
rifaction?
of the departing atoms, and thus copy the wood in
stone. Such copies are called petrifactions.
BORON.
What is 60- 486. DESCRIPTION. — Boron is a brown
ron ? powder, never seen except in the chemists
laboratory, and of no practical value. It occurs in
nature, combined with other elements, as borax arid
boracic acid.
487. BORACIC ACID. — This acid is com-
Hoio 'is bora-
cic acid form- monly seen in the form of white pearly
scales. It exhales with volcanic vapors
which issue from the earth in Tuscany. These va-
pors are condensed in water, and the solid acid is
obtained by evaporating the solution. The acid is used
like borax, as a flux. It is bitter, rather than sour, to
the taste, but is called an acid because it forms salts.
HYDROGEN.
488. DESCRIPTION AND OCCURRENCE. —
What is hy- • i i AS
drogen? Hydrogen is a colorless gas, about one fif-
occurl dOCS U teenth aS heaVy aS the air' li 1S °f SUch
extreme tenuity, that it may be blown
through gold leaf, and kindled on the opposite side.
One-ninth part of the ocean, and the same proportion
of all water in existence, is hydrogen gas. It enters,
198 HYDROGEN.
also, largely into the composition of all animal and
vegetable matter, and forms the basis of most liquids.
489. PREPARATION. — Introduce a few
Describe the
method of pre- bits of iron or zinc
paring iff ^ ft yial one_third
filled with water. Add a tea-
spoon-full or more of common
sulphuric acid, and attach to the
vial a bent tube or a clay pipe,
as represented in the figure. The evolution of the gas
immediately commences. The first portions, which
contain an admixture of air, are allowed to escape ; the
pipe-stem is then brought under the mouth of the vial,
and the gas collected.*
590. EXPLANATION. — Water is compos-
Explain the
formation of ed of oxygen and hydrogen gases. Each
hydrogen? WQuld be & ag but for
holds it in the liquid form. In the above process for
preparing hydrogen, the zinc is, as it were, the ransom
paid for its liberation. The oxygen combines with
the zinc and the hydrogen escapes.
491. Pure water will not suffice in the
What purpose
is served by process. It must contain acid, to unite
the acid? with the Qxide of zinc? as fagt ag formecl>
The presence of an acid, for which the oxide has great
affinity, seems to stimulate its formation. It may,
* When a taper can be applied at the mouth of the pipe-stem without
explosion, it may be certainly known that an unmixed gas is in pro-
cess of evolution. A cloth should be thrown over the vial and this test
made before commencing the collection. The connection of the ap-
paratus in the above experiment is made with a paper stopper, formed
on a bit of pipe-stem or glass tube.
HYDROGEN. 199
indeed, be regarded as a general law, that the pres-
ence of acids promotes the formation of oxides, and
vice versa.
492. ANOTHER METHOD. — Hydrogen
Give another J
method ofpre- may also be made, by passing steam through
a heated gun-barrel, containing bits of
iron. Bundles of knitting needles are commonly em-
ployed for the purpose. The steam leaves its oxygen,
combined with the iron, and escapes as hydrogen gas.
493. COMBUSTION OF HYDROGEN. — Bring
What i* pro- , ,
duced by the a dry, cold tumbler, over a burning jet of
combustion of hydrogen. The vessel will soon become
hydrogen f
moistened on the interior. The water
thus produced, is a result of the combination of hydro-
gen with oxygen of the air. But for the cold surface,
with which it is brought into contact, it would have
escaped into the air as vapor. The composition of
water was shown in Part 1., (•§> 277,) by galvanic de-
composition. It is here demonstrated by combining
its elements, and thus reproducing it. Water is also
formed in the combustion of any substance containing
hydrogen as one of its constituents. The above expe-
riment may therefore be made with a lighted lamp or
candle, as well as with the jet of pure hydrogen.
494. EXPLOSION OF MIXED OXYGEN AND
How is an ex-
plosive mix- HYDROGEN. — Allow oxygen to flow into an
turcprepared? inverte(i ^ as directed in para-
graph 330, until it is one-third full. Fill it up
with hydrogen, collected as shown in Par. 489.
Cork the vial under water. It is now filled with
an explosive mixture, which may be fired by the
200 METALLOIDS.
application of a taper. To secure against accident, the
precaution should invariably be observed, of winding
the vial with a towel, before the discharge.
495. EXPLANATION. — The explosion re-
Why does this
mixture ex- suits from the fact that all of the hydrogen
plode? ^n tjie v-aj kurns at oncej causing great
heat, and sudden expansion of vapor. The combus-
tion is thus simultaneous, because oxygen, the sup-
porter of combustion, is present at every point. When,
on the other hand, a jet of hydrogen is kindled, no
explosion occurs, because the combination is gradual.
Combustible hydrogen meets with oxygen in this case,
only on the surface of the jet.
n , -i th 496. THE HYDROGEN GUN. — The expe-
hydrogen gun, riment for the explosion of mixed hydro-
and the me- -, . -, -,
thodofcharg- gen and oxygen gases, may be made in a
ing it. strong tin tube, provided with a vent near
the closed end. Such a tube, about an inch in diame
ter, and eight inches in length, is called the hydrogen
gun. In loading it, the vent is stopped with wax,
the tube filled with water, and the gases, previ-
ously mixed in the right proportion, poured upward
into it, as indicated in the figure. The
gun, being thus loaded, is tightly
corked, under water, and afterward
fired at the vent. The explosion is
sufficient to expel the cork with vio-
lence, accompanied by a loud report.
The vial from which the tube is loaded
must not be too large, or it will not be practicable to
turn it and pour upward, as desired. This difficulty
HYDROGEN. 201
may also be obviated, by the substitution of a water-
pail, for the bowl represented in the figure.
497. CHARGE OF AIR AND HYDROGEN.
Describe an-
other explosive As air contains uncombmed oxygen, a
mixture of air and hydrogen also forms an
explosive mixture. But, as air is only one-fifth oxy-
gen, five times as much of it must be used ; in other
words, five parts of air are required, for every two
parts of hydrogen. To make the mixture, hydrogen
may be led, as before, into an inverted vial, a little
more than two-thirds full of air. The exact propor-
tion is not essential in this, or any similar case of ex-
plosive mixture.
498. A SIMPLER METHOD. — A simpler
Give a sim- ,-•/.,
pier method method of loading the gun, or charging
°^adin9the the vial with the explosive mixture, is to
invert it over a jet of hydrogen, as repre-
sented in the figure. The pipe-stem, or tube,
which conveys the gas, is previously wound
with paper, till it occupies about two-thirds of the
inner space of the gun. Escaping hydrogen fills
the remainder. On withdrawing the tube, air
enters to take its place, and the gun is thus
charged with mixed air and hydrogen, in the right
proportions. It is then corked and fired. This
experiment may also be made with a test-tube,
discharging it at the mouth. Explosions with mixed
air and hydrogen, are, of course, less violent than
where pure oxygen is used instead of the diluted oxy-
gen of the air.
Docs hydrogen 499. HYDROGEN WILL NOT SUPPORT COM-
support com- ' % . J .: ;
bustion? BTTSTION. — Flame is extinguished in hy-
9*
202 METALLOIDS.
drogen, as it would be in water. Re-charge the gas
bottle, if necessary, and hang a second large-mouthed
vial above it, as represented in the figure. Af-
ter a few minutes, it may be presumed that
the tipper vial is filled with hydrogen. Apply
a lighted match to its mouth, and the gas will
inflame, and continue to burn with a faint
light. Introduce a second taper, as represent-
ed in the figure. It will be kindled at the
mouth of the bottle, and again extinguished
above. The match is extinguished, because, a little
abo've the mouth of the vial, there is no oxygen to sup-
port the combustion of the carbon and hydrogen, of
which it is composed.
500. HYDROGEN MADE BY THE METAL
Describe the ./*,-,
preparation SODIUM. — Another very beautiful, but more
expensive method of making hydrogen
gas, is as follows. Fasten a piece of me-
tallic sodium, of the size of a pep-
per-corn, upon the end of a wire, and
thrust it suddenly under the end of
a test-tube filled with water, and held
very near the surface, as represented
in the figure. The metal melts as soon as it touches
• the water, and rises to the top of the tube. Hydrogen
is immediately formed, and displaces the water, fill-
ing the tube rapidly with the liberated gas.
Explain the 501. EXPLANATION. — Sufficient heat is
process. evolved by the action of sodium on water
to fuse it at once. The metal is lighter than water,
and therefore rises to the top of the tuba. At this
WATER. 203
point the chemical process begins. Sodium has the
most intense affinity for oxygen, and therefore com-
bines with this element of the water, setting its hydro-
gen at liberty. No acid is required as in the case of
zinc. Metallic potassium may also be used in this
experiment. To avoid its ignition by contact with
the water, it is to be wrapped in paper, and the twisted
end of the wrapper used as a holder, with which to
thrust it under the mouth of the tube.
WATER.
502. COMPOSITION. — Many important
Of what is , J _
water com- properties of water have already been il-
posed lustrated in the chapter on Vaporization.
Others will be mentioned below. It is composed of
oxygen and hydrogen, as has already been proved both
by analysis and synthesis. These gases are condensed
in combination to about a^Vo- of their original volume.
It remains to show how the exact proportion in
which they enter into the composition of water is as-
certained.
503. FIRST METHOD OF PROOF. — One
Describe the .
method by gal- method is to decompose water by the gal-
vanic Process> and collect and weigh the
gases obtained. The oxygen is found to
weigh eight times as much as the hydrogen. Water
is thus shown to be composed of eight parts of oxygen,
by weight, to one part of hydrogen. In other words,
nine pounds of water contain eight pounds of oxygen
and one pound of hydrogen.
204 METALLOIDS.
504. SECOND METHOD. — Another method
Show how com- . -,•->->
.position by is to measure the gases obtained by the
7al9culatedy ^ same method of decomposition. Two
from measure, measures of hydrogen are thus obtained for
every single measure of oxygen. The chemist then pro-
ceeds to calculate the relative weight. Knowing before-
hand that hydrogen is the lighter gas, weighing but
one-sixteenth as much as the same quantity of oxygen,
he infers that the double volume obtained in the above
experiment, weighs but one-eighth as much as the
oxygen obtained in the same decomposition. The
result of this indirect process is the same as that stated
at the conclusion of the last paragraph.
Describe the °Q5- THIRD METHOD. — A third method
third method, consists in the reproduction of water from
mixed hydrogen and oxygen, observing at the same
time the quantities in which they combine. This may
be readily effected in a test-tube. The gases being
introduced into the tube in about the right proportion,
and in small quantity, its extremity is
then intensely heated. A slight explo-
sion and combination of the gases is the
result, and the water rises to take their
place, mingling with the small quantity
of water produced in the experiment. Any excess of
either gas remains uncombined. Whether this surplus
is oxygen or hydrogen, may be readily proved by
methods previously given. This excess being sub-
tracted from the quantity of the same gas originally
used, shows the proportion in which the combina-
tion has occurred.
WATER. 205
506. The explosion may be avoided,
How may the . '
explosion be and a gradual combination of the gases ef-
fected, by evaporating a few drops of pla-
tinum solution in the test-tube, and igniting the residue
previous to the commencement of the above experi-
ment. A ball of fine iron wire is then crowded into
the end of the tube. The mixture of gases being
finally introduced, the least touch of flame upon the
end of the tube is sufficient to effect a gradual combi-
nation. For an explanation of the agency of plati-
num in the above experiment, the student is referred
to the chapter on metals. The iron wire serves to
prevent ignition, and consequent explosion, by appro-
priating part of the heat produced by the combination
of the gases. The form of the experiment last de-
scribed, is the only one that can be recommended to
the student. With the security against explosion
which it affords, a test-tube filled with the mixed gases
may be submitted to experiment. Where very accu-
rate results are sought, the process must be conducted
in a carefully graduated tube. By employing mercury
instead of water, the water produced in the experiment
may be seen.
507. FOURTH METHOD. — Still another
Give the meth- . .
od by oxide of method is illustrated in the figure. It con-
essential-
ly, in the production of
water from its elements as
before ; furnishing, at the
same time, the means of as-
certaining the proportional weight of the gases, which
have taken part in its formation. The tube most
206 METALLOIDS.
distant from the aspirator* is first filled with oxide of
copper, and then heated while a current of hydrogen
gas is drawn over its surface. The heated hydrogen
carries with it the oxygen of the copper, and passes
into the second tube, as vapor of water. Here it is re-
tained by potassa, or some substance of similar proper-
ties. Both tubes are afterward weighed, and their gain
or loss determined, by comparison with their weight
before the commencement of the process.
508. The loss of weight in the one tube.
How are the
results calcu- expresses the weight of the oxygen which
it has furnished for the formation of water ;
the gain in the second tube, gives the weight of the water
thus formed. The difference of the two, gives the
weight of the hydrogen which has been appropriated
in its passage, and now makes part of the newly formed
water. For every nine grains of water thus produced,
it is found that eight grains of oxygen, and one of hy-
drogen have been consumed. Its precise composition
is thus demonstated, by another and quite distinct pro-
cess.
What is said 5®$> SOLUTION. — Water is a very gene-
of solution ? rai soivent. The disappearance of salt, or
sugar, in water, is an example.f Transparency is es-
sential to a solution. Where the particles of a solid
are distributed throughout a liquid, as when chalk is
* A vessel employed, as in the present instance, to produce a current
of air or gas, is called an aspirator.
t Water also di-solves many gases. The ammonia of the shops is
prepared by passing gaseous ammonia in water.
WATER. 207
stirred with water, it is said to be diffused, instead of
dissolved. The solvent action of water plays a most
important part in nature, as will be seen in the conclu-
ding chapter of this work. The subjects of solution,
and precipitation, are more fully considered in the
chapter on Salts.
Wkatispre- ^10. PRECIPITATION. — Where a substance
dpitation ? which has been dissolved, is re-converted
into a solid form, it is said to be precipitated.
Thus, when air from the lungs is blown
through a quill or pipe-stem into water, the
lime combines with the carbonic acid from the
lungs, and falls to the bottom of the vessel, in
the form of solid particles of chalk. The
solid thus produced, is called a precipitate.
511. FILTRATION. — Filtration is
What is filtra-
tion, and hoio the separation of a precipitate
is it effected? from the Uquid m which it jg con-
tained. This is effected by throwing the mix-
ture into a paper cone, which retains the
solid, while the liquid passes through its pores.
Such a filter is prepared by folding unsized paper into
the shape of a quadrant, which is then opened, so as
to form a cone, commonly supported in a glass funnel.
It is possible, in small experiments to dispense with the
funnel, as is done in the figure, and even to use ordi-
nary newspaper, in the place of that especially pre-
pared for the purpose.
208 METALLOIDS.
5 12. CRYSTALLIZATION. — Dissolve
Howmaycrys- ir i r i • • ^
ta^s of alum be hall a pound oi alum in a pint of
obtained? boiling water, and hang a cotton cord
in the vial. As the water cools, crystals will form
on the thread. Bonnet wire may be bent into the
shape of baskets, miniature ships, &c., and cov-
ered, by this means, with a beautiful crystalliza-
tion.
Explain the 513. EXPLANATION. — Hot water has for
process. most substances greater solvent power
than cold water. In the case of alum, for example, water
slightly warmed, will dissolve twice as much as cold
water. It follows, that as the hot water becomes cold,
part of the alum must become solid again. In so
doing, the particles, in obedience to their mutual at-
traction, arrange themselves in crystals, as described
in the first Chapter III.
514. SNOW CRYSTALS. — Snow flakes are
What is said 1-1
of snow crys- always either grouped or single crystals,
and their form may often be distinctly seen
with the naked eye. They
are best observed by catching
them upon a hat, or other
dark object, and inspecting them in the open air.
515. CHEMICAL COMBINATIONS. — Water
What is said
of the combi- unites with both bases and acids, to form
nations of wa- hydrate^ Thus? ^^ lim^ ^ formg hy_
drate of lime ; with sulphuric acid, hy-
drated sulphuric acid. Most of. the oxygen acids, in
the form in which we employ them, contain water in
a state of combination, and are therefore hydrated
WATER. 209
acids. They may also be regarded as salts, of which
oxide of hydrogen or water is the base.
What is said 516. RELATIONS TO LIFE. Water forms,
feiatioLfo US by far' the Sreater Part of a11 animal and
life? vegetable matter, as will be more fully
seen in the portion of this work which treats of or-
ganic chemistry. To water, the leaf of the vegetable
and the muscle of the animal, owe, in a great degree,
their pliancy and freedom of motion. In view of these
and other relations to life, the negative properties of
water are not the least important. Had it taste, 01
odor, however exquisite, we should soon weary of them.
And but for its mild and neutral character, it would
irritate the delicate nerves and fibres which it bathes.
517. At very high temperatures the va-
Whnt is the J
effect of water por of water decomposes many minerals,
ratureksfmp€' and exPels strong acids from their com-
pounds. Under the stimulating influence
of heat, this neutral liquid becomes a chemical agent
of extreme energy. Such decompositions as are here
referred to, are without doubt, constantly going on be-
neath the surface of the earth.
COMPOUNDS OF HYDROGEN, WITH CHLORINE, BROMINE,
IODINE, FLUORINE, AND SULPHUR.
Under this head are to be described a new series of
acids, distinguished by the absence of oxygen from all
which have hitherto been mentioned The molecules
of each, like those of water, are composed of single
atoms of their constituents.
210 METALLOIDS.
They are all gaseous, and are sometimes called hy-
dracids, from the hydrogen which enters into their com-
position. Their salts are described in Chap. III.
HYDROCHLORIC ACID.
518. DESCRIPTION. — Hydrochloric acid
*s a c°l°rless gasj fuming, by contact with
add? What the air. It sometimes issues from volca-
is said of its , . ,, . . ,, . ,
occurrence? noes, but is, tor the most part, an artificial
product. Its solution in water is known
as muriatic acid.
519. PREPARATION. — Gaseous hydro-
prepa'ratlon. chloric acid, may be produced, like water,
by the direct combination of its elements.
For this purpose, equal volumes of the two gases are
mixed by candle-light, or in carefully covered bottles,
and then exposed to the direct rays of the sun. The
action of the light is so intense, that on throwing a
bottle, thus filled, from shadow into sunlight, it imme-
diately explodes. The explosion is a consequence of
the energetic union of the two gases, under the influ-
ence of the chemical rays of the sun. The acid pro-
duced is at once dissipated in the air. Great caution
should be used in this experiment, for even the diffused
light of day has been known, in some instances, to
occasion explosion.
520. ANOTHER METHOD. — Hydrochloric
Describe an-
other mode of acid may also be made from common salt,
preparing it ? which fumishes the chlorine, and ordinary
hydrated sulphuric acid , which furnishes the hydrogen.
HYDROCHLORIC ACID.
211
A tea-spoonfull of common salt is introduced into a
test-tube, with about the same
bulk of water. Half as much
acid is added, then the mixture
gently heated, and the acid gas
led into water, as shown in the
figure. Water absorbs, at ordi-
nary temperatures, 480 times
its own volume, of the gas.
There is no occasion, for the
purpose of experiment, to carry on the process till it is
thus saturated. A few minutes will suffice to make an
acid strong enough to dissolve zinc.
Explain the 52 1. EXPLANATION. — Hydrated sulphu-
process. rjc %(,[& fras always a strong tendency to
form metallic salts. In this case it takes the metal,
sodium, from the common salt, and thereby converts
itself into sulphate of soda. At the same time it gives
back hydrogen to the salt, in place of its lost sodium,
converting it, by the exchange, into hydrochloric acid.
The process just described, is the one always employed
in the manufacture of hydrochloric acid.
522. ACTION OF HYDROCHLORIC ACID ON
What metals ,, , . , -IT i
does hydro- METALS. — Hydrochloric acid dissolves tm>
chloric dis- an(j a]j of fae meta|s which precede it in
solve ?
the chapter upon metals. For tin, a hot
and concentrated acid must be employed.
523. The solution depends on the fact
On what does
the solution that the metals take chlorine, from the
depend? hydrochloric acid, thereby converting
themselves into soluble chlorides. The hydrogen then
212 METALLOIDS.
assumes the gaseous form, and escapes with lively ef-
fervescence. An experiment may best be made with
zinc, to which a little dilute acid is added.
What is aqua 524. AQUA REGiA. — On mixing muriatic
regia? ac{^ with half of its bulk of strong hydro-
chloric acid, aqua regia is produced ; so called, from its
regal power over the noble metals. Gold and platinum,
which are not effected by either acid alone, dissolve
readily in aqua regia. The solvent power of aqua re-
gia depends, as before explained, on the nascent chlo-
rine which it supplies.
525. HYDROBROMIC AND HYDRIODTC ACIDS.
^lobromicand These acids are of interest to the chemist
hydriodie only. They resemble hydrochloric acid,
acids ? . .
in being colorless gases, strongly acid,
soluble in water, and capable of dissolving many
metals.
HYDROFLUORIC ACID.
526. DESCRIPTION. — Hydrofluoric acid
What is hy-
drofluoric is a colorless, corrosive gas, acting on glass,
and many minerals which other acids do
not affect. It condenses into a liquid, at the freezing
point of water. It is not known to occur ready formed
in nature.
527. PREPARATION. — Hydrofluoric acid
How is hydro-
fluoric acid is made Irom a mineral called fluor spar,
prtpar by ttie game meai)S employed to make hy-
dochloric acid. On account of its corrosive action on
glass, vessels of lead or platinum are employed in the
HYDROFLUORIC ACID. 213
process. This gas is so poisonous, when inhaled, and
its solution so corrosive to the skin, that its prepara-
tion, in any considerable quantity, should be left to the
experienced chemist.
Explain the ^28. EXPLANATION. In the above pro-
process ? cess, the fluor spar, which is a fluoride of
calcium, furnishes the fluorine, and hydrated sulphuric
acid, the hydrogen. The remaining constituents unite
to form sulphate of lime, which remains in solution.
529. ETCHING ON GLASS. — It has already
cess for etch- been stated that hydrofluoric acid attacks
wg glass. glass, and many minerals. By covering
with wax, they may be protected against the corrosion.
Advantage is taken of these two facts in etching
upon glass. The surface is first slight-
ly warmed and rubbed with beeswax,
and then warmed again, to produce an
even coating. Figures, or letters, are
then drawn upon the glass, through the wax, with
a pen-knife, or other pointed instrument. The plate,
being now exposed for a few minutes, to the fumes
of hydrofluoric acid, and the wax subsequently re-
moved, is found to be deeply etched. Fumes of hy-
drofluoric acid, for the purpose, are best obtained by
placing a half tea-spoonful of pulverized fluor spar,
in a warm tea-cup, and covering the powder with oil
of vitriol. A little ether, or potash, will be found of
use in removing the last portions of wax from the
plate.
Explain the 530. EXPLANATION. As OXygeil COm-
above process, bines with carbon to form carbonic acid, so
214 METALLOIDS.
the hydrofluoric acid eats out the silicon of the glass,
where it is exposed, and passes off with it, in the form
of a new and more complex gas. A solution of the
gas may be prepared by the process employed for hy-
drochloric acid. Bottles of vulcanized India rubber,
or gutta purcha, may be used in keeping the solution.
HYDROSULPHURIC ACID.
531. DESCRIPTION — Hydrosulphuric acid
What is hy- .
dromlphuric is a colorless gas, also known as sulphu-
retted hydrogen. It has a putrid odor and
feeble acid properties. Like the rest of the series, it
is soluble in water. It occurs in many natural waters,
called sulphur springs. It is one of the products of
the decomposition of animal matter, and the source of
much of the disgusting odor which they emit during
putrefaction.
Howisitpre- ^32. PREPARATION. — It is made from
pared? sulphuret of iron, as hydrochloric acid
is made from common salt ; and hydrofluoric acid
from fluor spar. In the above process, sulphuret
of iron furnishes the sulphur, and hydrated sul-
phuric acid, the hydrogen. The remaining elements
unite to form sulphate of iron, which remains in solu-
tion. On account of the disgusting smell of the gas,
it is best to prepare it only in small quantities.
533. DISCOLORATION OF METALS AND
What effect
has it on met- PAINTS. — The blackening of silver watches
als, &c. ? an(j coingj in tjae vicinity Of Sulphur
HYDROSULPHURIC ACID. 215
springs, is an effect of hydro-sulphuric acid gas. Its
discoloring effect may be illustrated, by pouring a little
dilute sulphuric acid upon a few grains of sulphuret of
iron, in a tea-cup, and holding a bright moist coin in the
fumes. Its effect on paints may be shown by exposing
a piece of paper, moistened with solution of sugar of
lead, in the same manner. The white paper immedi-
ately assumes a dark metallic stain. Paper moistened
with a solution of tartar emetic, takes a deep orange hue.
This experiment is often varied, by drawing amusing
figures on paper, with lead solution, and bringing them
out by exposure to the gas.
534. EXPLANATION. — The change of
Explain the ,
cause of the color in each case, is owing to the forma-
toior9e°f tion of a metallic sulphide, having a diffe-
rent, and generally a darker color. Zinc
is not blackened, because its sulphide happens to be
white. For this reason, chemical laboratories, and other
places where hydrosulphuric acid is likely to be evolved,
should be painted with zinc paints, instead of those
containing lead.
535. RELATIONS TO LIFE. — Sulphuretted
What is the
effect of ml- hydrogen, if inhaled in any considerable
?f on ow- quantity, acts as a poison. Caution should
therefore be observed, in experiments with
this gas. The mixture of gases which is given off
from recently ignited coal, contains sulphuretted hy-
drogen acid, in large proportion, and owes its deleterious
qualities, in considerable part, to this admixture.
216 METALLOIDS.
AMMONIA.
536. DESCRIPTION. — Ammonia is a col-
WTiat is am-
monia? orless gas, of pungent smell, and alkaline
Pr°Perties-. It is exhaled from vdlcanoes,
and is a product of the decomposition of
all vegetable and animal matter. Its molecule contains
one atom of nitrogen to three of hydrogen.
mi . . .j 537. PRODUCTION FROM ITS ELEMENTS.
What ^s said
of its produc- Although nitrogen and hydrogen gases are
trogen°andhy- the sole elements of ammonia, they cannot,
drogent under ordinary circumstances, be made to
unite directly, and form it. Heat does not stimulate
their affinities sufficiently to bring about this result.
Electrical sparks passed, for a long time, through a
mixture of the gases, cause them to combine to a lim-
ited extent.
538. PRODUCTION FROM NASCENT ELE-
Production
from its nas- MENTs. — Iron, at a high temperature, ex-
cent elements. pelg hydrogen from ordinary hydrate of
potassa, and nitrogen from nitre. If heated with both
together, it expels both nitrogen and hydrogen, and the
two nascent elements unite, to form ammonia. The
experiment may be performed by covering bits of potash
and nitre with iron filings, and heating them in a test-
tube. Another method of producing ammonia, through
the agency of platinum sponge, is described under the
head of Platinum.
How is ammo- 539t PREPARATION.— Ammonia is com-
ma common- monly made from salts that contain it, by
ly prepared ?
using some strong base to retain the acid,
AMMONIA.
217
and set the gas at liberty. Potash or lime may be
used for this purpose. Introduce into a test-
tube about half an inch of a stick of fused potash,
and covered it with powdered sal-ammoniac.
On the addition of water to dissolve them, am-
monia will be immediately evolved. Rest the
tube on the table, and place a wide-mouthed
vial over it to collect the gas.
540. SOLUTION IN WATER. — AQUA AMVIO-
How is its so-
lubility in wa- NIA. Bring the mouth of the vial filled with
ter proved? ammoniacal gas, quickly, into a bowl of
water. The water will swallow up the gas so rapidly as
to rise and fill the vial, producing a weak solution of
ammonia, or hartshorn. If only a small portion of
water be allowed to enter, and the vial be then re-
moved from the bowl and shaken, the hartshorn ob-
tained will be comparatively strong. For the prepira-
tion of the solution in large quantity, the method given
in the section on Chlorine is to be preferred. The
vial should be previously warmed. Newly slaked lime
may be substituted for potash.
How ma,, the 54L A MINIATURE FOUNTAIN.— Fill a
ammonia be pint vial with ammonia, by
employed to
produce a jet the method above given, and
of water ? immediately introduce, air-
tight, into its mouth, a moist paper
stopper, with a bit of pipe-stem run
through it. Then invert the bottle into
O
a bowl of water. The absorption by
the first portions of water that enter will be so com-
10
21$ METTALLOIPS.
plete as to produce a vacuum, into which more wa-
ter will rise, in a jet, as represented in' the. figure.
542. ALKALINE PROPERTIES. — Bring the
Explain its
action on material for making ammonia into a tea-
acids' cup, or similar open vessel. Hold a strip
of litmus paper, previously reddened by an acid, in the
gas, as it is evolved. The acid will be neutralized by
the ammonia, and the paper restored to its original color.
Any substance which is very soluble, and neutralizes
strong acids, is called an alkali. As ammonia has this
property, arid is also volatile, it is therefore called a vol-
atile alkali. The same experiment with litmus paper,
may be also made with the hartshorn obtained in the
last experiment.
543. JT FUMES WITH ACID VAPORS.—
Describe its . ,
effect on acid Moisten a piece of paper with strong mu-
vapors. riatic acid, and wave it to and fro through
the gas. White fumes are produced, by the
union of the muriatic acid and the ammonia.
In uniting, they produce small particles of mu-
riate of ammonia, or sal-ammoniac, in the air.
It is of these that the fumes consist. It will
be observed, that in this experiment the ma- j||
terial from which the ammonia was originally pre-
pared is reproduced. The same fumes are formed,
on waving a paper moistened with muriatic acid through
the atmosphere of a stable. Ammonia is constantly
evolved in such places, from the decomposition of ani-
mal matter.
PHOSPHURETTED HYDROGEN. 219
PHOSPHURETTED HYDROGEN".
544. DESCRIPTION. — Phosphuretted hy-
Whatisphos- . r J
pkurettedky- drogen is a colorless gas, of an odor that
drogen? hag been compare(i to that Qf putrid fish.
It is spontaneously inflammable by contact with the
air. In the relative proportion of its elements, it cor-
responds with ammonia. This gas is sometimes pro-
duced in the decay of vegetable and animal matters.
The jack-o-lantern, or will-o-t he-wisp, sometimes seen
in swamps and grave-yards, is supposed to have its
origin in the spontaneous production and combustion
of this gas.
How is it pre- 545. PREPARATION. — Phosphuretted hy-
pared? drogen is made from phosphorus, with the
help of water and an alkali. Water furnishes the requi-
site hydrogen, if lime or potash is at the same time
present. Introduce into a small vial two-thirds full of
water, a stick of ordinary fused potash, broken in pieces,
and a bit of phosphorus of the size of a pea. On the
application of heat, this gas is evolved. It is carried
through a pipe-stem, and al-
lowed to bubble up through
water contained in a tea-cup
or bowl, as represented in the
figure. If the atmosphere is
still, the bubbles, as they burst
and inflame, form beautiful
white rings, which rise in succession into the air.
These rings consist of particles of phosphoric acid,
produced by the combustion of the phosphorus which
220
METTALLOIDS.
is contained in the gas. In order that the gas may be
safely evolved, it is best to heat the vial in a tea-cup
containing salt, dissolved in three times its bulk of
water. The addition of salt has the effect of raising
the boiling point. The comparatively high tempera-
ture required, may thus be obtained without exposure
of the vial to the direct flame of a lamp.
Explain the 546. EXPLANATION. — In the action which
above process, occurs in making phosphuretted hydrogen
from potash, water, and phosphorus, the latter plays
the part of an extremely rapacious element. It makes
no distinction in the objects of its appetite, but seizes
upon both oxygen and hydrogen of the water, two
substances as widely different from each other as pos-
sible. It forms with the one, phosphuretted hydrogen,
and with the other, what might be called phosphuret-
ted oxygen, but is, in fact, an acid. Potash is em-
ployed in the process, to promote the formation of this
acid. In its absence, water resists the affinities of the
phosphorus, and neither acid or phosphuretted hydro-
gen are obtained.
COMPOUNDS OF HYDROGEN WITH CARBON.
547. Most of the compounds of carbon and hydro-
gen belong to the vegetable world, and will therefore
be more properly considered in the chapter on organic
chemistry. Only two of them, which exist ready
formed in nature, will be here mentioned.
CARBURETTED HYDROGEN.
LIGHT CARBURETTED HYDROGEN.
What is u kt ' ^ESCRIPTION- — Light carburetted
carburctted hydrogen is a colorless, inodorous, in-
Whcre does it flammable gas, about half as heavy as
occur? ajr jts moiecule contains two atoms of
carbon to four of hydrogen. It is produced in ponds and
marshes, by the decomposition of vegetable matter under
water, as will be more fully explained in Part III. From
this circumstance it is also called marsh gas. Mixed
with other gases, it issues from fissures in coal mines,
forming the fire damp, formerly so much dreaded, on ac-
count of its explosive properties. As coal is of vegeta-
ble origin, the gas of the mines which proceeds from
it is also traceable to the vegetable world. In some
districts, and more particularly in regions where
borings are made for salt, it issues from the earth in
sufficient quantity to form the fuel which is required
to boil down the brine, or even to illuminate villages.
How is it pre- 549. PREPARATION. - An
pared? impure, light, carburetted hy-
drogen, is obtained from wood, by simple
heating. For this purpose, saw-dust, or
bits of shavings are heated in a test-tube.
The gas may be burned in a jet as fast as
formed. The product thus obtained is
not pure, but mixed with olefiant, and
other gases, which make the flame more
luminous. The pure gas, may be made
from strong vinegar, (acetic acid,) by the agency of
heat and potash, as will be explained in the latter part
of this work.
222 METTALLOIDS.
550. EXPLOSIONS IN MINES. — Marsh gas
Explain the . , .
cause of explo- forms, with air, an explosive mixture be-
*ion in mines? fore alluded ^ which is often the occa-
sion of fearful accidents in mines. The experiment
may be made with olefiant gas, which has the same
explosive property. This property belongs, indeed, to
most gases and vapors which contain hydrogen ; as for
example, to the vapors of ether, alcohol, camphene,
and " burning fluid/'
551. DAVY'S SAFETY LAMP. — The dis-
Descnbe Da- . . « •» -.-i »• t i • r-v -i • i
vy's safety tinguished English chemist, Davy, devised
lamp. a method Of security against these explo-
sions. It consists in surrounding the
miners' lamp with wire gauze, which
will admit air through its insterstices,
but will not let out flame to ignite the
explosive atmosphere of the mine.
This effect may be illustrated, by
holding down a piece of wire gauze upon the flame of
a candle. If the gauze is fine, the flame will not
pass through it. This effect is owing to the reduc-
tion of temperature which the wire occasions. The
subject will be better understood by reference to the
paragraphs which follow, on the nature of flame.
HEAVY CARBURETTED HYDROGEN.
552. DESCRIPTION. — Heavy carburetted
What are the {
properties of hydrogen is a colorless gas, of peculiar
defiant gas? ^ezl\$\\ odor, also known as olefiant gas.
CARBURETTED HYDROGEN. 223
It is nearly twice as heavy as the light carburetted hy-
drogen just described, and contains twice the quantity
of carbon. It forms a small proportion of the Jire
damp, of mines, and salt borings, before described.
How is it pre- 553. PREPARATION. — Heavy carburetted
pared? hydrogen is made from alcohol, by the de-
composing action of sulphuric acid. Bring into a test-
tube a tea-spoonful of alcohol, with a little sand, and
add four times as much oil of vitriol. On heating over
a spirit lamp, the gas is evolved, and may be burned
like the gas just described, at the mouth of the tube.
The acid employed, has the effect of retaining part of
the elements of the alcohol, and allows the rest, to
escape as olefiant gas. The reaction* is more fully ex-
plained under the head of organic chemistry.
554. ILLUMINATING GAS. — Gas for illu-
How is illu-
minating gas mination, is commonly prepared from bitu-
minous coal. Such coal is principally
composed of carbon and hydrogen. A portion of
these elements, pass off under the influence of a high
temperature, in the form of gas. The product, is
rather, a mixture of gases, among which light and
heavy carburetted hydrogen are the principal. The
process may be illustrated, by heating a little pulver-
ized bituminous coal in a test-tube. If the heat is in-
tense, coal tar will be produced at the same time. The
illuminating power of gas is principally derived from
heavy carburetted hydrogen. Its quality, within cer-
tain limits, depends on the relative proportion of this
constituent.
* The term reaction, signifies, in chemistry, the mutual action ot
chemical
224 METALLOIDS.
How is it pu- 555. PURIFICATION. — The gas as it rises,
rifled f contains ammonia and sulphuretted hydro-
gen, two impurities which it is desirable
to remove. The first may be stopped
in its passage, by a loose wad of moist-
ened paper ; the last, by a similar wad,
moistened with solution of sugar of lead.
The papers having been introduced, the
pipe-stem is fitted to the tube with a pa-
per stopper, and the tube heated over the
alcohol flame, with the help of a blow-pipe. When
the coal has become red hot, the gas will pass off in
sufficient quantity to be ignited, at the extremity of
the tube.
How ore the ' ^ ^ conclusion of the process,
impurities the upper wad contained in the tube, will
be found blackened by the sulphuretted
hydrogen which it has retained. On removing the
second one, it will be found to smell of ammonia. The
presence of this body may also be shown, by the fumes
which it yields with muriatic acid.
557. ARRANGEMENTS IN GAS WORKS.—
Describe the
process in gas The process in gas works is essentially the
same, as that above described. The coal
is heated in iron retorts. The tar collects in pipes lead-
ing from it. Carbonate of ammonia is washed out by
a jet of water, which plays in an enlargement of the
pipe. Lastly, sulphuretted hydrogen is removed by
the retentive power of a metallic base, lime being gen-
erally substituted for lead.
FLAME. 225
558. COLLECTION AND DISTRIBUTION. —
After purification, the gas is collected in
lectedand dis- }™e n.on holders, called easrmeters.
tributed ?
Tiiese may be represented by the inverted
tumbler of the figure. Gas pouring
in from below would lift and fill it. <^TS^
If an orifice were made in the top,
the tumbler would immediately set-
tle into the water. The air would,
at the same time, escape through the
orifice. The distribution of illumina-
ting gas, from public gas works, is effected on the
same principle. The weight of the sinking gas-
ometer, is sufficient to press it through pipes, to all parts
of a large city.
559. GAS FROM WOOD. — Gas may be
How may gas
be made from made from wood, by the same means
above given. Only a moderate heat is re-
quired, in this case, to produce tar at the same time.
Gas of higher illuminating power than that prepared
from wood or coal may also be made from oil fat or
rosin. Even refuse vegetable substance may be em-
ployed. A pound of dried grape skins have been found
to yield 350 quarts of excellent illuminating gas. The
dried flesh of animals has sometimes been employed
for its manufacture.
FLAME.
What is said 560. FLAME. — Nothing in nature is, to
of flame ? tjie uninstrilcted eye, more mysterious than
flame. It is, seemingly, body without substance, and
10*
226
METALLOIDS.
shape, without coherence. It is created by a spark,
and annihilated by a breath. Invulnerable itself, it
destroys whatever it touches. Divided and subdivided,
it is still the same, yet endowed with the power of re-
solving other materials into their elements. Chemistry
resolves this mystery, and gives us the satisfaction of
definite knowledge in its place. But, as in all similar
case, while satisfying the understanding, it opens new
fields to the imagination. The subject of combustion,
as involved in flame, introduces us, for example, to a
knowledge of the grand system of circulation of mat-
ter as set forth in the last chapter of this work.
561. STRUCTURE OF FLAME. — EXPLANA-
J5sfa«in the
nifitdnre of TioN. — Every lamp or candle, is
a gas factory, in which gas is k
first produced out of oil or fat, by the fire
which kindles it, and afterward by heat the
of its own flame. A flame, if carefully ob-
served, will be found to consist of three
distinct parts ; a dark centre, a luminous
body, and a faint blue envelop. The dark
centre, is unburned gas. The body of the
flame consists of particles of carbon or lamp-
black, heated white hot, by the combustion
of hydrogen. In the exterior blue envelop,
the carbon particles are consumed as they
are crowded outwards, by the flow of newly-formed
gas.
562. EFFECT OF FLAME ON METALS. —
What is the
effect of flame If a tarnished penny be held perpendicu-
larly in the flame of a lamp or candle, the
on metals ?
FLAME. 227
portion within the flame will lose its coating of oxide,
while the exterior portions at the same time become
more deeply oxidized, and consequently, darker colored.
It is because there is an excess of carbon arid hydro-
gen in the interior of the flame, to take oxygen from
the metal, by their superior affinity, and pass off with
it as gas or vapor. In the outside, on the other hand,
there is an abundant supply of air to impart oxygen,
or, in other words, to oxidize. By moving the coin to
and fro after it is once thoroughly heated, the instanta-
neous conversion of metal into oxide, and oxide into
metal, may be readily observed. A beautiful play of
colors, like those upon a soap bubble, will be found to
attend the transformation. The flame of a spirit lamp
is, in some respects, preferable for this experiment.
563. OXIDIZING FLAME. — The blue en-
What is the
oxidizing velop of the flame, which, with the hot
air adjacent, has the property of oxidizing
metals, is called the oxidizing flame.
564. REDUCING FLAME. — The body of
What ift the _J
reducing the flame, which, with the heated gas
flame ? within it, has deoxidizing effects, and re-
duces oxides again to the metallic form, is called the
reducing flame. The process of deoxidizing is called
reduction.
565. THE BLOW-PIPE. — The peculiar
effects of both the oxidizing and reducing
simple con- flame, may be still better obtained, by help
ftructton.
of the simple mouth blow-pipe. In want
of a metallic tube, a common tobacco-pipe, to the bowl
228 METALLOIDS.
of which a piece of a second stem is fitted,
as represented in the figure, may be made
to answer the purpose. With its aid, a
lamp or candle flame is converted into a
miniature blast furnace. The mouth is ap-
plied at the end of the long stem, while
the shorter one carries the blast to the flame. The
orifice of the latter should be extremely small. It
may be so rendered, by filling with clay, and then
piercing it with a needle.
566. OXIDIZING BLOW-PIPE FLAME. — To
d oxidize with the blow-pipe, the flame,
for oxidation? mixed with a large proportion of oxygen,
Give an ex- . _ . . ..
ample. is blown forward upon the metal, or other
material, subjected to experiment. This is
effected by introducing the extremityof the blow-pipe,
a little within the flame.
The air of the lungs be-
comes thus mixed with
the rising gases. The
result is, a slender, blue
flame, at the point of
which, within its fainter blue envelop, the metal is
to be held. A piece of lead, of the size of a grain of
wheat, placed on charcoal, hollowed out for the purpose,
and exposed to the flame, will soon bo converted into
litharge. The oxide will be recognized by the yellow
incrustation which it forms upon the charcoal support
567. REDUCING BLOW-PIPE FLAME. — To
How is the
blow-pipe used convert oxides into metals, or in other
blow-pipe, the gases of the flames are
FLAME.
229
blown forward, upon the substance, mixed with little
air. The extremity of
the blow-pipe is placed
against the outer wall of
the flame, a little higher
than in the previous case.
The flame thus produced
is yellow, and of the shape represented in the figure.
The oxide to be reduced, is to be placed within the
yellow body of the flame, but near its termination.
The litharge produced in the last experiment, may
be re-converted, by this means, into metallic lead.
568. OXYHYDHOGEN BLOW-PIPE. — The
Describe the compound or oxhydrogen blow-pipe, as
oxyhydrogc*
blow-pipe. commonly constructed, consists of two
gasometers, containing, the one, oxygen,
and the other hy-
drogen gas. Tubes
leading from these,
are brought together
at their extremity,
and the two gases are
burned in a single jet.
The heat thus pro-
duced, is the most in-
tense that has ever
been realized except
by galvanic means. Iron, copper, zinc, and other metals,
melt and bum in it readily ; the former, with beau-
tiful scintillations, and the latter, with characteristic
colored flames. With a sufficiently constant flame
10*
230
METALLOIDS.
platinum also may be readily fused. The apparatus
represented in the figure, furnishes a simpler means of
obtaining similar results/ An abundant flow of hy-
drogen is required, and a pint bottle should, therefore,
be employed in its preparation. To retain it free from
water, which would tend to reduce the heat of the
flame, a little cotton may be introduced into the bowl
of the pipe through which it passes. In evolving the
oxygen, only a part of the tube should be heated at a
time, lest the gas should be too rapidly evolved.
FLAME CONTINUED. — The student will
ture of flame already have found abundant evidence that
{rai«rf£ UlU8~ air or oxygen *s essential to combustion.
A still more striking illustration of the sub-
ject remains to be given. A phosphorus
match, if suddenly introduced into the
interior of a flame, notwithstanding the
high temperature in its vicinity, is not
ignited. The wood burns off, but the
phosphorus of the match does not un-
dergo combustion. The same principle
may be illustrated by holding a match
for a moment through the body of the
flame. It is consumed at the sides,
while the centre remains unburned.
CLASSIFICATION OF METAI-3. 231
CHAPTER II.
METALS.
569. CLASSIFICATION. — The metals may
How may the
metals be das- be arranged in groups, or classes, according
to their affinity for oxygen. Those which
tarnish, or rust most readily, come first in order, while
the last group is made up of the noble metals, which
retain their brilliancy, unimpaired.
570. CLASS i. POTASSIUM AND SODIUM.
Describe the
metal* of These two metals combine with oxygen so
eagerly, as to tarnish instantaneously, on
exposure to the air. They even seize on that which
is contained in water and expel its hydrogen. The
hypothetical metal, ammonium, is described in connec-
tion with this group, because of the similar properties
of its compounds.
Describe Class 571. CLASS II. BARIUM, STRONTIUM, CALCI-
IL UM, MAGNESIUM. — The metals of this class
show their affinity for oxygen, in the same manner as
those of Class I. But they are inferior, in this respect, to
both potassium and sodium. Either of these metals
can deprive them of the oxygen with which they may
have combined.
Describe Class 572. CLASS III. MANGANESE, ALUMINIUM,
IIL IRON, CHROMIUM, COBALT, NICKEL. The
metals of this class tarnish less rapidly than the fore-
going, by exposure to the air. In order that they may
decompose water, and appropriate its oxygen, they re-
232 METALS.
quire the stimulus of an acid, or of heat. Except in
the case of manganese, the heat must be sufficient to
convert the water into steam. Strictly speaking, there-
fore, they do not decompose water, but steam.
Describe Class 5?3. CLASS IV. TlN AND ANTIMONY.—-
IV- Tin and antimony tarnish less readily than
the metals of the previous class. To enable them to
decompose water, and appropriate its oxygen, they re-
quire the stimulus of a red heat. An acid, or mode-
rate heat will not suffice.
Describe Class ^74. CLASS V. COPPER, BISMUTH, AND
LEAD. — Although copper and lead become
tarnished, or covered with a thin film of oxide, rather
more readily than the metals of the last two groups,
their affinity for oxygen under other circumstances is
less. This is evident in the fact that a red heat ena-
bles them to decompose water and appropriate its oxy-
gen, but feebly. Acids will not suffice. Bismuth
does not tarnish so readily as copper or lead.
Describe Class 5?5. CLASS VI. MERCURY, SILVER, PLA-
VL TINUM, AND GOLD. — The metals of this
class do not tarnish, and do not decompose water under
any circumstances. Even if made to combine with
oxygen by other means, they yield it again very readily,
and return to the condition of metals. They are called
the noble metals.
POTASSIUM. 233
CLASS I.
POTASSIUM.
576. DESCRIPTION. — Potassium is a
bluish White metal> Hghter than Water>
solvents; and soft, like bees-wax. Like wax. it is
occurrence?
also converted by the heat of an ordinary
fire into vapor. Water and acids dissolve it readily.
The metals of this and the folloAving groups, were dis-
covered by Sir Humphrey Davy, early in the present
century. They were first produced by the galvanic
process. Potassium is a constituent of many rocks,
of all fertile soils, and of the ashes of plants. The
more important minerals which contain it, are men-
tioned in Chapter III.
577. PREPARATION. — Potassium is made
flow is potas-
sium pre- from carbonate of potassa, by removing
pared? jtg carbolu'c acid and ox-
ygen. This is accomplished by
heating intensely with charcoal, which
removes both in the form of carbonic oxide.
The metal which accompanies the gas, in the form
of vapor, is condensed by naptha, instead of water.
The process is essentially the same as that for preparing
phosphorus, but requires apparatus beyond the reach of
the ordinary experimenter. Cream of tartar, if heated,
is converted into a nearly suitable mixture of carbonate
of potassa, and pure carbon, for this purpose. A small
quantity of charcoal, in fragments, is added, and the
whole heated intensely in an iron retort.
234
METALS.
Explain the 578. COMBUSTION ON WATER. PotaS-
actionofpo- gmm jf thrown UDOll
tassium on r
water. water, is immediately
ignited and burns with a beautiful
violet flame. Strictly speaking, it is not potassium
which burns, but the hydrogen which it sets at liberty,
Owing to its strong affinity for oxygen, it takes this
element from water, liberating, and at the same time
kindling, the hydrogen with which it was before
combined. The color of the flame is due to a small
portion of vaporized potassium which burns with
this gas, as it is evolved. The globule of metal used
in this experiment, gradually disappears, because the
potassa which it forms by uniting with oxygen, is
soluble in water.
579. USES OF POTASSIUM. — Potassium
State the uses
of potassi- has not been applied to important uses in
the arts, but is a valuable agent in the
hands of the chemist. It is a key which unlocks
many substances from the prison in which nature has
confined them. Through its agency, brilliant metals
may be obtained from lime, magnesia, and common
clay.
580. This effect depends on the supe-
On what does
its action dc- nor affinities of potassium, which enable
pcnd? -t to appr0pr{ate oxygen, chlorine, and
other substances, with which the above, and several
other metals are combined in nature, and to isolate the
metals themselves. The potassium is, at the same
time, converted into oxide, or chloride of potassium,
SODIUM. 235
which is soluble in water, and may be washed away
from the metal which has been produced.
SODIUM.
581. PROPERTIES. — The metal sodium is
Sodium — de-
scription, similar in its properties to potassium. It
^dvni^and *s PrePared by similar means, from carbo-
occurrcnce? nate of soda, and may be employed by the
chemist, for the same purpose. It occurs, principally,
in nature, in the form of common salt. Thrown upon
water, it decomposes it, without however igniting the
hydrogen which is evolved.* Sodium is readily sol-
uble either in water or acids.
582. USES OF SODIUM. — Sodium is now
.For K'hat pur- .
pose is it prepared in large quantities, in France,
as a material to be used in the manu-
acture of the metal aluminiu n. Its cost, a few years
since, was ten dollars an ounce. It can now be pro-
cured for less than a dollar per pound.
AMMONIUM.
583. Ammonium is a compound of ni-
Wkat is said . .
of ammoni- trogen and hydrogen, which is presumed
um' to be a metal. Its molecule contains one
atom of nitrogen, to four of hydrogen. If a metal, it
differs from all others, in being a compound, and not a
simple element. There are, however, good grounds
* If sodium is wrapped in paper, to prevent waste of heat, it burns
with flame, like potassium, upon water.
236 METALS*
for believing in the existence of such a compound
gaseous metal. The chloride of ammonium is named
in accordance with this view. Judging from the prop-
erties of the salt, we might reasonably expect, by re-
moval of its chlorine, to obtain from it a substance
with metallic properties, as well as from chloride of
sodium or common salt. But the experiment does not
justify the expectation. As soon as the chlorine is re-
moved, the metal also decomposes, and a mixture of
gases is the result. The principal ground for attribu-
ting a metallic character to the combination of nitrogen
and hydrogen gases, in the preparations above stated,
has been already indicated. They supply, in certain
salts, the place which known metals fill in the other
and similar compounds. A confirmatory experiment
is described in the succeeding paragraphs.
584. AMMONIUM AMALGAM. — Another
Slate another ...., . ~
reason for be- ground for believing in the existence of
lexScelofea ammonium, with true metallic properties,
metal ammo- is found in the following experiment : If
nium. „ . • i • i
chloride of ammonium be mixed with an
amalgam of sodium and mercury, a double
decomposition ensues. The chlorine and
sodium unite to form common salt, while the
mercury combines with the ammonium with-
out losing its metallic lustre. But there is no
instance of this retention of metallic properties in the
combination of mercury or any other metal with any
non-metallic substance. The inference is that ammo-
nium is a metal. But any attempt to isolate it by re-
BARIUM.
237
moval of the mercury from the amalgam, is ineffectual.
As soon as this is done the ammonium is resolved into
gaseous ammonia and hydrogen. This change takes
place, indeed, spontaneously.
585. In performing the above experiment,
How is the
amalgam ex- a small globule of potassium or sodium is
formldl peT~ heated with a thimble full of mercury in a
test-tube, and a strong solution of sal am-
moniac added. The mercury increases in bulk without
losing its lustre, and continues to expand till it fills the
tube or glass with a light pasty amalgam.
CLASS II.
BARIUM, STRONTIUM, CALCIUM, MAGNESIUM.
586. BARIUM. — Barium is a soft silvery
pro- metal, easily tarnished in the air. It is
ami made from baryta, by the process already
described under the head of potassium.
Its compounds, including baryta, from which it is pre-
pared, are hereafter described. Barium is soluble in
water and most acids.
587. STRONTIUM. — Strontium is very
Strontium — „ .
description, similar to barium, but darker in color. It is
absolvents? Produced from strontia by a similar process.
Its solvents are also the same.
588. CALCIUM. — The metal calcium is
Calcium — de- . .
pro- similar to barium, and is made from lime
b>" the use of Potassium, as before de-
scribed. Its solvents are the same as those
of the metals above-named.
238
METALS.
Magnesium- 589' MAGNESIUM.— Magnesium is a Soft
description, white metal, prepared from its chloride
preparation, , . .
solvents and instead oi the oxide, by similar means.
None of the metals of this class have as yet
been applied to any useful purpose in the arts. Water
oxidizes magnesium as it does the other metals of the
class, but converts it into an insoluble white powder.
Most acids dissolve it.
CLASS III.
ALUMINIUM
590. DESCRIPTION. — Aluminium is a
bluish white metal, made from common
currence, and cjay. It is about one-third as heavy as
solvents ? * y
iron. It fuses at the same temperature
as silver, and preserves an untarnished surface in the
air. It does not decompose water, even with the aid
of boiling heat. Alloyed with iron, it protects the
latter from the action of the air. This metal is a con-
stituent of common clay, and therefore a part of all fer-
tile soils and the rocks that produce them. It is also
a constituent of numerous minerals. By its discovery
every clay bank is converted into a mine of precious
metal.
How is it pre- 591. PREPARATION. — Aluminium is pre-
pared? pared like magnesium, from its chloride,
by fusion with potassium or sodium. The latter rnetal
is commonly employed. The fluoride may also be
used in the process, or the mineral cryolite, which
MANGANESE. 239
is a compound of fluoride of aluminium with fluoride of
potassium. The latter constituent interferes in no wise
with the process. The method of preparing the chlo-
ride, as a material for the production of the metal, is
given in the section on Chlorides.
592. ACTION OF ACIDS. — Muriatic acid
What is the .
action of acids is its proper solvent, and forms with it a
colorless solution. Nitric acid whitens it,
if previously dipped into strong potash or soda. Dilute
sulphuric acid is without action. Aluminium may be
poured from one vessel to another in a fused condition
without oxidation. Like silver it may be deposited by
the galvanic process.
593. It is highly sonorous, and therefore
other proper- adapted to manufacture of bells. This
metal is now prepared in France at less
than three dollars per pound. The French government
propose to use it for helmets and cuirasses, for which
it is especially fitted by its lightness and tenacity.
594. MANGANESE. — Manganese is a
description, grey brittle metal, produced from its oxide
production, b heatnig wjth charcoal. It is found in
occurrence,
solvents and nature as black oxide of manganese and as
a constituent of many other minerals. It
enters also in small proportions into the composition of
soils. Diluted sulphuric or muriatic acid are its proper
solvents, forming with it pale rose-colored solutions.
The black oxide serves as a source of oxygen, and is
also employed in the preparation of chlorine gas. It is
also used in the production of artificial amethysts, and
also to impart to glass the same violet tint.
240 METALS.
CLASS III.
IRON.
595. DESCRIPTION. — Pare iron is nearly
Mention some
properties of white, quite soft, exceedingly malleable
and highly tenacious. It may be rolled
into leaves so thin that a bound book containing forty-
four such leaves shall be only one-fifteenth part of an
inch in thicknesss. In the condition of perfect purity
it is never seen except in the chemist's laboratory.
Even the purest iron of commerce contains traces
of other substances. Dilute sulphuric or
muriatic acids are its proper solvents, form-
ing with it green solutions. The addition
of nitric acid, or chlorine, changes the color
to red. Iron may be readily burned, as has al-
ready been shown in the section on Oxygen.
596. OCCURRENCE. — Iron is a most
Does metallic .
iron occur in abundant metal, but is rarely or never
nature? found in the metallic form, excepting as
meteoric iron. In this condition it is always alloyed
with nickel. The latter metal being uniformly com-
bined with it in masses known to have fallen to the
earth as meteors, its presence in similar masses dis-
covered on the surface of the earth, is regarded as evi-
dence of their meteoric origin. Iron is a constituent
of a great variety of minerals, of all soils and plants,
and even of the blood of animals. The peroxide of
iron, the magnetic oxide, and clay iron stone, are its
principal ores. Whole mountains of the magnetic oxide
exist in Missouri, and in Sweden.
IRON.
241
How is iron
produced ?
597. PRODUCTION. — Iron is produced
from its ores, which are impure oxides, by
heating with lime, to remove
the impurity ; and at the
same time with coal, and
the gases proceeding from it,
to remove the oxygen. A
smelting furnace, such as is
represented in the figure,
being previously heated, is
charged with the material in
layers, and the heat main-
tained by the coal of the
mixture. In the upper part
of the furnace the materials
are thoroughly dried. As
they gradually settle, they
become more thoroughly heated, and meet carbonic
oxide from the coal below, which robs the iron of its
oxygen, and converts it into particles of metal. Still
lower down, the lime combines with the earthy por-
tions of the ore, forming a liquid glass. The re-
duced iron thus liberated, collects, fuses, arid sinks to
the bottom of the furnace. Prom this point it is run
off into channels of sand, where it hardens into pig
iron.
How is the 598. EXPLANATION. — The ordinary im-
slag formed? purities of the ore- are clay and quartz, or
For what uses r j T. ?
may it be em- silica. Lime has the property of forming,
p oye with both of these, a fusible glass, or slag,
which floats upon the melted iron. This material is
11
242
METALS.
of a light green color. But it may be otherwise col-
ored to suit the taste, and cast into slabs, columns, ar-
chitectural and parlor ornaments of great beauty.
The process by which its brittleness is removed, and
the slag adapted to the above uses, has not been made
public.
599. CAST IRON — The pig or cast iron,
Give the com- . .
position and as it is called, which is thus obtained from
PcraTiron°f the furnace> is not Pure iron> but a con>
pound of iron with carbon. It has ob-
tained four or five per cent, of this element from the
coal with which it was reduced. The addition of
carbon to its composition causes iron to melt more
readily. But for its absorption, the metal would not
have become sufficiently soft to flow from the fur-
nace. Carbon has also the opposite property of mak-
ing iron harder and more brittle when cold. Castings
of agricultural implements and other objects, are made
by remelting the pig iron, and pouring it into moulds
of the required shape.
600. WROUGHT IRON. — Wrought iron is
How is
wrought iron made from cast iron, by burning out its
made? carbon. This done in what is called a
reverberatory furnace, such
as is represented in the fig-
ure. The carbon is burned
out by the surplus air of the
flame, which is made to play
upon the molten iron. Prom
the constant stirring which is essential, such a furnace
for refining iron is called a puddling furnace. The
IRON. 243
metal becomes stiffer as it loses carbon, and is then
hammered and rolled into bars.
601. IRON WIRE. — The bar. or wrought
Mention an
important iron thus produced, is highly malleable and
wrought iL. ductile> aild ma7 be rolled into sheets, or
How i$ iron drawn into the finest wire. Wire is made
wire made ?
by drawing a wrought iron bar, by ma-
chinery, through a hole of less than its own diameter,
and repeating the process until the required degree of
fineness is attained. Wrought iron loses its tenacity,
and becomes granular and brittle, like cast iron, by long
jarring. This effect sometimes occurs in the wheels
and axles of railway carriages, and is the occasion of
serious accidents.
602. WELDING. — Wrought iron becomes
How is
wrought iron soft at a certain heat, without melting.
This property, which adds greatly to its
usefulness, belongs to no other metal excepting plati-
num. In the soft state, two pieces may be united by
hammering. This process is called welding. The
surfaces to be welded are sprinkled with borax, to pro-
tect them from the air, which would form a crust of
oxide of iron, and prevent a perfect contact. Its fur-
ther action is explained in the chapter on Salts. Beside
borax, other materials having a similar effect are fre-
quently employed.
How is steel 603. STEEL. — Steel may be made from
made ? cast iron by burning out half its carbon.
Or it may be made from wrought iron, by return-
ing half of the carbon which was removed in its
preparation. The latter is the process generally pur-
244
METALS.
sued. It consists in burying the wrought metal in
iron boxes containing charcoal, and heating it for
several days, till combination with a certain portion
of the carbon is effected.
604. ANNEALING. — The hardness of
How is steel . .....
made soft or steel depends upon the rate at which it is
cooled. By heating it to redness, and
cooling it slowly, it is rendered as soft and malleable as
wrought iron. This process is called annealing. By
cooling it very suddenly, it becomes as hard and brittle
as cast iron. Steel instruments are commonly ham-
mered out of the soft steel, and subsequently hardened.
How is steel 605. TEMPERING STEEL. — Steel hardened
tempered? as above described is too hard and brittle
for most uses. Any portion of its original softness and
tenacity may be returned to it, by reheating and slow
cooling. To restore the whole, a red heat would be
required. To give back part, and make a steel so
tough as not to break readily, yet sufficiently hard for
cutting, a lower temperature is employed. This process
is called tempering. The sort of temper imparted de-
pends upon the degree of heat which has been em-
ployed.
606. The proper temperature is ascertained
How is the , . , , ,
proper heat by the color which the steel assumes when
ascertained? heated< Toolg for cutting metal are heated
till they become a pale yellow ; planes and knives, to
a darker yellow ; chisels and hatchets, to a purplish
yellow ; springs, till they become purple, or blue. In
each case they are afterward slowly cooled. These
colors are owing to a film of oxide of iron, which is
CHROMIUM.
245
formed upon the steel under the influence of heat. The
tint is different, according to the thickness of the
film. All these colors may be seen by heating a knit-
ting-needle in the flame of a spirit lamp. Where it is
hottest it becomes blue, and this color shades off into
pale yellow on either side, like the colors of the solar
spectrum.
Chromium —
CHROMIUM.
607. DESCRIPTION. — Chromium is a grey
. *
description, metal, not readily tarnished, and so hard
Po™f"so!™nts, aS t0 SCratch glass' Jt is of no use in the
and uses? arts in the metallic form. It is found in
combination with iron, as chromic iron, and also in
beautiful Crystals, as red chromate of lead. It may be
prepared from its oxide, like iron, by heating with
charcoal. Its compounds are much used as paints.
Chrome green and chrome yellow are among the
number. Its proper solvents are the same as those of
iron. The solutions of this metal are green.
COBALT
608. DESCRIPTION. — Cobalt is another
grey metal, tarnishing but slightly in the
air. It is somewhat malleable. It is found
combined with arsenic, as arsenical cobalt,
and in some other minerals. As metal,
it is without useful application in the arts. It may
be produced like iron, by heating with charcoal,
Cobalt— de-
scription, pro-
duction, oc-
currence, sol-
vents, and
uses ?
246 METALS.
but is more readily reduced by hydrogen. A cur-
rent of this gas being made to pass through a hot
tube containing the oxide, it combines with oxygen,
and passes off with it as water, leaving the metal in the
form of a fine powder. Its proper solvents are the
same as those of iron and chromium. The solutions
of cobalt are pink. The oxide is employed for im-
parting a blue color to glass.
NICKEL.
Nickel— 609. Nickel is still another grey metal,
' l[8hiQ* in color and more malleable than
ores, solvents, cobalt, and not much affected by the air.
and uses? •* • * i • i • • • « "
It is round in combination with copper, in
the mineral called copper nickel. It may be prepared
by either of the methods used for cobalt. Its proper sol-
vents are the same as those of the last four metals. The
solutions of this metal are green. Nickel is principally
used in the preparation of the alloy called German sil-
ver. This imitation of silver is brass rendered white
by the proportion of nickel which it contains. The
alloy is composed of one hundred parts of copper, six-
ty of zinc, and forty of nickel.
ZINC.
610. DESCRIPTION. — Zinc is a bluish-
— de-
scription, white metal, readily tarnished in the air.
Jt is brittle at ordinary temperatures, and
converted into vapor at a red heat. If
ZINC. 247
heated somewhat above the temperature of boiling wa-
ter, it can be rolled into sheets. At a higher tempera-
ture it again becomes brittle. Sulphuric and muriatic
acids dissolve it readily, forming colorless solutions.
It is not found native. The red oxide, and the carbon-
ate, called calamine, are among its more important ores.
611. PRODUCTION. — Zinc is produced
produced? from its oxide by heating with charcoal to
remove tne oxygen? or> m other words, to
reduce it. When made from the carbonate,
the ore is previously roasted, to expel
its carbonic acid and bring it to the
state of oxide. As the metal is volatile
at the heat required in its reduction, an
ordinary furnace, such as is used for making iron, can-
not be employed in the process : the metal would be
lost in vapor. A clay retort, or muffle, such as is re-
presented in the figure, is used instead. The zinc va-
por condenses in the cool neck, and falls, in drops of
melted metaLinto a vessel of water placed to receive
it. The carbonic oxide produced in the process at the
same time, escapes into the air. It will be observed,
that the process is essentially the same as that for pro-
ducing potassium and phosphorus, as before described.
Acids dissolve zinc, forming colorless solutions.
612. ACTION OF HEAT AND AIR. — Zinc
How may zinc -:-
be burned? may be burned by heating it on charcoal,
in the blow-pipe flame. It melts, and con-
verts itself rapidly in the process into
white oxide of zinc. If an intense
heat is employed, the vapors of the
metal burst through the crust and burn
248 METALS.
to oxide, with a brilliant greenish flame. When zinc
is burned in considerable quantity, in a highly heated
crucible, the oxide forms flakes in the air, to which the
name of lana philosophica, or philosophers' wool, was
given by the alchemists. The metal may be melted
over a spirit lamp, in an iron spoon.
Mention the 613. USES OF ZINC. — Zinc is principal-
uscs of zinc. \y employed in the form of sheet zinc, for
roofing and similar purposes. It is also used, like tin,
as a coating to protect iron chains and other objects
from rust. The coating is effected by plunging the
iron into molten zinc, which forms an alloy upon its
surface. The iron thus coated is sometimes called gal-
van' zed iron, though without reason, as is evident from
the above process. Solutions of zinc are sometimes
used to prevent the decay of wood, and to render it
less combustible. It has also been employed with
success, as a substitute for copper, in sheathing vessels.
CLASS IV.
TIN.
x
614. DESCRIPTION. — Tin is a brilliant
Describe the . .. „ .. . _
metal Tin. white metal, very soft and malleable, and
From what t easily tarnished. When a bar of tin
ore is it made? *
is bent, it gives a peculiar grating sound,
fancifully called the cry of tin. This is a consequence
of the friction of the minute crystals of tin of which
it is composed. Its only ore is an oxide, called tin
TIN. 249
stone, of which Cornwall, England, is the principal
locality.
How is tin 615. PRODUCTION. — Tin is produced,
produced ? \fae jron an(j most other metals, by heating
its oxide with carbon. The materials are heated in a
small blast furnace. The carbonic oxide produced in
the fire, as before explained, is the reducing agent. It
takes the oxygen from the ore, and passes off with it
as carbonic acid, while the metal fuses, and runs to the
bottom of the furnace. By heating tin before the
blow-pipe, it is rapidly converted into white oxide.
How do adds 616. ACTION OF ACIDS. — Tin resists
act on tin ? weak acids remarkably. Dilute muria-
tic and sulphuric acids, which dissolve most of the
metals before described, act upon it but feebly. The
concentrated acids dissolve it with comparative ease.
Its solution, although less poisonous than those of
lead, are still injurious to health. Acid food should,
therefore, never be allowed to stand for a long time in
tin vessels. The solutions of tin are colorless.
617. Nitric acid acts upon tin with en-
Whatisthe
action of ni- ergy ; but, like a ferocious animal that de-
tnc acid? stroys without devouring its prey, leaves
it undissolved. It converts it into a white
insoluble powder of oxide of tin, with the
evolution of the usual red fumes. This case
is an exception to the usual action of nitric
acid. One portion of the acid commonly
acts to produce oxide, while another portion dissolves
the oxide formed. The experiment for the solution
11*
250 METALS.
of tin may be made with tin-foil, in a tea-cup or test-
tube.
618. Aqua-regia,) it will be remembered.
What is the °
action of aqua- is a mixture of nitric and muriatic acids.
regia on tin ? Jn most caseg they ^ &g before degcribedj
in concert, to dissolve metals that neither can dissolve
alone. They act thus, also, upon tin, in small por-
tions. But if larger quantities are employed, the mix-
ture grows warm, and the nitric acid, as if stimulated
beyond restraint, attacks the metal for itself, and con-
verts it, as when it acts alone, into a white powder.
619. COATING PINS. — Common brass pins
How are pins
coated with are coated, by boiling with cream of tartar
tin? and tin-foil, or bits of tin. The acid of
the tartar acts as solvent. Tin is then deposited on
the mere electro-positive brass, as in cases of galvanic
decomposition. At every point where brass, tin, and
the liquid are in contact, a small galvanic battery is, in
fact, produced.
How is tin 620. TIN WARE. — Tin is cast in va-
plate made ? rious forms, for culinary and chemical uten-
sils. A little lead is added to give it greater tough-
ness. Common tin ware is made of sheet-iron, coated
with tin. The coating of the metal is effected by
dipping well cleaned sheet-iron into molten tin.
621. CRYSTALLINE TIN. — Tin has a great
How may the "
crystalline tendency to assume a crystalline form.
*tinCbele.en? The stmcture may be observed on wash-
ing the surface of ordinary tin plate with
aqua-regia, to remove the thin coating of oxide. It
may be still better seen if a tin plate is heated over a
ANTIMONY. 251
lamp till the coating melts, then suddenly cooled, and
afterward cleaned as above directed. The whole sur-
face is then found to be covered with beautiful crys-
talline forms.
AOTIMONY.
Describe the 622. DESCRIPTION. — Antimony is a blu-
ish white and hi§hly crystalline metal
what ore is it which does not tarnish in the air. It is
obtained? 1-11
so brittle that it may be readily reduced to
powder. The ore from which the metal is produced is
the grey sulphuret, or antimony glance.
623. PRODUCTION. — Antimony may be
How is anti- . .
monypro- obtained from its oxide, by the usual pro-
cess of reduction. The sulphuret is first
partially converted into oxide by roasting, and still fur-
ther by carbonate of soda, which is added in the sub-
sequent process. It is then mixed with charcoal, and
intensely heated in crucibles. At a white heat the
metal fuses, and sinks to the bottom. The soda added
in the process exchanges its oxygen for the remaining
sulphur of the ore.
624. ACTION OF HEAT AND AIR. — If heated
How may an- ... , •,«» 4
timony be before the blow-pipe, antimony soon melts,
and burns with a white flame. It is at the
same time converted into oxide. A portion of the oxide
escapes into the air, while the rest forms
a white coating upon the charcoal sup-
port. At the high temperature which
is here produced, the affinity of the
252 METALS.
metal for oxygen is so stimulated, that the molten
globule will continue to burn, even if removed from
the flame. By directing a stream of air upon it,
from a pipe-stem, the combustion may be maintained
till the globule is entirely consumed.
625. If the molten globule be allowed
Describe an P ,, ,, n •••
experiment to fall upon the floor, it im- .
with the mol- mediately divides into hun- x
ten globule? '"^ >• •
dreds of smaller globules, which —jjjs&Z...
radiate in all directions, leaving each a dis- - '//', I V\\
tinct track of white oxide behind it.
What is the 626. ACTION OF CHLORINE. — A shower
rinelnanti-' of fire may be Produced ^Y sprinkling fine
many ? powder of antimony into a vial containing
chlorine gas. The metal is hereby converted into a
white smoke of chloride of antimony. In its rela-
tions to the principal acids, antimony resembles tin.
Its solutions are colorless.
627. USES OF ANTIMONY. — The principal
What are the f . .
principal uses use of antimony is in the preparation of
of antimony? alloySj io ^Q hereafter described. Among
these, type metal is the most important. Many of the
compounds of antimony, like other poisonous sub-
stances, are used with advantage in medicine. Tartar
emetic is one of these medicinal compounds contain-
ing antimony.
BISMUTH 253
CLASS V.
BISMUTH.
Bismuth— -de- ^^' DESCRIPTION. — Bismuth is a brittle,
script-fan, sol- crystalline metal, of a reddish white color.
vents, and oc- . .
currence in It is used in making certain alloys. Like
antimony, it can be readily ground to pow-
der. Crystals of bismuth may be obtained by
the method described in the section on sulphur,
as represented in the figure. Nitric acid is its
proper solvent, and forms with it a colorless solution.
Bismuth is found native, forming threads of metal in
quartz rock. Its most productive localities are in
S axony.
629. PRODUCTION. — The metal is pro-
How is bis- .
muthprodu- cured from the rock which contains it, by
simple heating, in inclined tubes. At a
comparatively moderate temperature the bismuth fuses
and runs down into vessels placed to receive it.
630. EFFECT OF HEAT AND AIR. — The
What is its
action before same experiments before the blow-pipe,
thcbloiv-pipc? and with moiten globules, which were
described in the case of antimony,
may be made with bismuth. The
only difference is, that the metal does
not burn with flame, and that the coat-
ing of oxide on the charcoal is yellow, instead of white.
631. USES OF BISMUTH. — Its principal
What are the
uses of bis- use is in the preparation of alloys, to be
muth? described hereafter. One of them has the
254
METALS.
remarkable property of fusing in boiling water. Seve-
ral compounds of bismuth are used in medicine ; the
sub-nitrate, is also employed as a cosmetic. This
use of it is quite hazardous, as certain gases which are
often present in the air., have the effect, as will be here-
after seen, of changing its color to a deep brown or black.
Copper — de-
scription,
ores, solvents?
COPPER.
632. DESCRIPTION. — Copper is a red,
malleable, and highly tenacious metal. It
tamishes in the ^ but ig ]ess injure(} fty
rust than iron, and therefore more durable. Nitric acid
is its proper solvent, and forms with it a green solution.
Copper is found in abundance, in the metallic condi-
tion, on the southern shore of Lake Superior. It is
chiseled out, in masses, from the rocks which contain
it. The metal is more commonly obtained from a
mineral, called copper pyrites, which is a double sul-
phuret of iron and copper. It is also found as pure
sulphuret, red oxide, and carbonate. Minute traces of
copper are found in human blood.
633. PRODUCTION. — Copper is prepared
State briefly
the mode of from the impure
production. sulphuretj by
first burning out the sulphur,
in the air ; and secondly,
heating with charcoal, to
remove the oxygen which
has taken its place. Sand
is at the same time added, to form a floating slag with
the oxide of iron, and thus remove it from the molten
copper.
COPPER. 255
The oxide of iron thus removed, is derived from the
sulphuret of iron, which is a usual constituent of cop-
per ores.
634. Both of the above processes of
State further
particulars of roasting and heating with charcoal, and
epro sand, must be several times repeated
before pure metallic copper is obtained. It is to be
remarked that the formation of a slag, which shall
remove this iron, depends on the fact that its oxide is
by no means so easily reduced as copper. Being once
brought into the state of oxide, it remains in this con-
dition and unites with the silicic acid of the sand.
635. ACTION OF HEAT AND AIR. — Copper
What is the , .,..,.
effect of heat is readily oxidized m the air, at a high
temperature. Its oxidation may be ob-
served, by holding a copper coin in the flame of a spirit
lamp, as described in the section on Flame. The iri-
descent hues observed in the experiment, are owing to
the varying depth of oxide on different portions of
the coin. By long continuation of the process, the
whole surface is converted into black oxide. If it be
sooner suspended, and the coin plunged into cold
water, a coating of red oxide containing less oxygen
is obtained.
636. USES OF COPPER. — Copper is used
Mention some . . . , .
of the uses of ior a variety of purposes, for which iron
copper. would be less suitable, on account of its
rapid oxidation. Its employment in sheathing ships, is
an example. It is also a constituent of various alloys,
to be hereafter described. Among these, all gold and
silver coins, and the metal of gold and silver plate, are
included.
256
METALS.
LEAD.
637. DESCRIPTION. — Lead is a bluish
scription, ores grey metal, extremely malleable, and read-
and solvents? ^ tarnished in the air. It is heavier than
any other of the metals mentioned in this work, except
mercury, gold, and platinum. Nitric acid is its proper
solvent, forming with it, a colorless solution. The
principal ore of this metal, is galena, or sulphuret of
lead. Lead is also found as carbonate, sulphate, and
phosphate of lead.
How is lead 638. PRODUCTION. — Lead is obtained
obtained? from the sulphuret, by heating it with
iron, to remove the sulphur. A mixture of metallic
lead and sulphuret of iron are
thus produced, from which
the lead separates by its
greater specific gravity. If
the oxide of lead could be
readily obtained, the reduc-
tion by charcoal would be
as applicable here, as in the case of other metals.
639. A SECOND METHOD. — Another
method, is to heat the sulphuret with a
portion of sulphate. The sulphate has a large supply
of oxygen, while the sulphuret is destitute of this ele-
ment. The two may be mixed in such proportions
that they will together contain just enough oxygen to
carry off all the sulphur, as sulphurous acid. This
result having been accomplished by heat, the pure
metal of both remains behind. As a preparation for
JSxplain an-
other method.
LEAD. 257
this process, a portion of sulphuret is converted into
sulphate, by heating in a reverbaratory furnace. Both
parts of the process are in practice united ; a moderate
heat with abundant air being first supplied, a portion
of sulphate is produced. This is afterwards more
highly heated, with the undecomposed sulphuret which
remains.
640. ACTION OF AIR AND HEAT. — If
What occurs i-i-i i i c .1-11 • .1
when lead is ^ea(i is heated before the blow-pipe, in the
heated before oxidizing flame, it melts and disappears.
the blow-pipe ?
The charcoal support becomes at the same
time covered with yellow oxide of
lead or litharge. The grey coating
which at first forms upon the lead, is
an oxide containing less oxgen. If,
on the other hand, litharge is heated in the reducing
flame, it is converted into metal.
641. ACTION OF WATER. — Water, with
Wh,at is the r . .
action of water the help of the air which it always con-
on lead. tains, acts sensibly upon lead and becomes
in consequence poisonous. This action of water is
most decided when it contains no foreign matter. On
being conducted through leaden pipes it becomes
therefore more impure as a consequence of its very
purity.
Whatprevents 642. The presence of sulphates and cer-
this action? tanl otner salts, such as are usually con-
tained in spring water, prevents this effect. The very
substances, whose presence in water we are accustomed
to regret as impurities, thus become our most efficient
protectors against the poisonous effects of lead.
258 METALS.
643. But this rule is not without ex-
Do impurities
always pro- ception. Certain substances seem to in-
crease the action. It is therefore always
prudent where it is proposed to conduct water through
leaden pipes, to ascertain by direct experiment, whether
the particular water in question acts upon the lead or
not.
644. ILLUSTRATION. — The difference in
Describe the .
experiment the action of pure water upon lead, and
™ithlead and that which contains foreign substances in
distil Lea water.
solution, may be readily proved by exper-
iment. For this purpose, bright slips of lead may be
placed in two tumblers, the one containing rain water,
and the other well or spring water. The former will
soon become turbid while the latter remains unaffected.
645. The presence of lead in the former
How may the
presence of case may be still more strikingly shown,
•fawn*/ ^eUeT ky adding to the water a few drops of a
solution of hydrosulpluric acid. The for-
mation of a dark cloud will show the presence of lead,
and indicate the danger to be apprehended.
646. LEAD TREE. — Dissolve some crys-
Describe the
lead tree and tals of sugar of lead, in thirty or forty
Us" production. timeS theif bulk °f Wat6r> and fil1 a vial
with the solution. A strip of zinc, hung
in the vial, will branch out in a beautiful ar-
borescence of metallic lead. It may be neces-
sary to clarify the solution by the addition of
a little clear vinegar or acetic acid. A day or
two will be required for the completion of
the experiment. The effect depends on the
MERCURY. 259
superior affinities of zinc for acetic acid. The zinc
takes away acid and oxygen from successive portions
of the sugar of lead, and leaves the particles of lead
subject to the laws of crystallization. At the same
time, the zinc having acquired possession of the acid
and oxygen, comes into solution as acetate of zinc. A
similar arborescence is produced in a solution of silver
by metallic mercury.
How are shot ^47. MANUFACTURE OF SHOT. Shot are
made? prepared by pouring melted lead through
perforated iron vessels. The drops are made to fall
from a great height that they may become cooled and
solidified in their descent. They are caught in water
that their shape may not be impaired. Having been
assorted by means of seives, they are" polished in
revolving casks, containing a small portion of black lead
or plumbago.
Mention other ^48. OTHER USES OF LEAD.— In the
uses of lead. form of sheet lead this metal is applied
to a variety of familiar uses. It is also largely em-
ployed in the manufacture of lead tubing. It is a
constituent of various alloys, among which pewter
and type metal are the more important.
CLASS VI.
MERCURY.
649. DESCRIPTION. — Mercury is a white
Mercury — de- - . , i /• i • i i
scription, sol- fluid metal of high lustre and beauty. It
"discover™? retains the fluid condition at all ordinary
temperatures,and is only rendered solid by
260 METALS.
extreme cold. Nitric acid is its proper solvent. Mer-
cury is sometimes found in the metallic form, but more
commonly as the sulphuret or cinnabar, which is its
principal ore. It is said that the mines in Mexico were
accidentally discovered by a native hunting among the
mountains. Laying hold of a shrub to assist him in
his ascent, he tore it up by the roots, and a stream of
what he supposed to be liquid silver flowed from the
broken ground.
How is mer- 650. PRODUCTION. — Mercury is prepared
cury obtained ? from the sulphuret, by simple roasting in a
current of heated air. This metal yields its sulphur so
readily to the oxygen of the air that no other agent is
essential in its production. The mercurial vapors pass
along with the gas, into tubes or chambers where the
temperature is lower, and are there condensed to the
liquid form.
Mention other 651. Mercury may also be produced from
methods. fae sulphuret by the employment of iron
filings to remove the sulphur, as in the case of lead.
Burned lime may also be used. Its calcium combines
with the sulphur and uses its own oxygen for the
partial conversion of the sulphuret thus formed into
sulphate of lime.
652. ACTION OF HEAT AND AIR. — Mercury,
What is the J7
action of heat like water, may be boiled away and con-
verted into vapor, by the application of
heat. At 39° below zero it freezes. It is
always to be borne in mind in experiments with this
metal arid its compounds, that its fumes as well as its
salts, are extremely poisonous. By free access of air and
MERCURY. 261
moderate heat, mercury may be gradually converted into
red oxide, but a higher temperature expels the oxygen
thus absorbed, and the oxide is again converted into
metal. This production of a metal from an oxide, by
heat alone, is characteristic of the noble metals. They
are loth to obscure their splendor in rust ; if it is forced
upon them, they need but little assistance of heat to
throw it off and re-assume their original beauty.
653. AMALGAMS — GLASS MIRRORS. —
What are
amalgams? Mercury combines with many metals form-
n?rs sUvered? *n& comPounds which are called amalgams.
When the mercury is in large proportion
they are fluid. Gold, silver, and lead, for example,
may be dissolved in mercury. This solvent power of
mercury is usefully applied in extracting gold from the
rocks which contain it. The beautiful silvering of
mirrors consist of an alloy of tin and mercury. Tin
foil is applied to the glass, and being afterward drenched
with mercury, the excess is removed by pressure. The
tin has thus absorbed about one-fourth of its own
weight of mercury.
654. A copper coin may be similarly
co°ppercoin be silvered, by rubbing with metallic mer-
curY> or keeping it well moistened for some
time with a solution of mercury in nitric
acid. If the solution is quite acid, it must first be
nearly neutralized by ammonia. The coin is to be af-
terward polished. The chemical action which takes
place in this case is similar to that explained in the
case of the lead tree. By drawing a line across a thin
brass plate, with a pen dipped in solution of mercury,
METALS.
the plate will be so weakened that it may afterward
be readily broken.
655. OTHER USES OF MERCURY. — The
Mention^ some compounds of mercury are extensively
mercury. used in medicine. Corrosive sublimate, a
poisonous chloride of mercury, is employed
for the destruction of vermin. It is also used in what
is called the kyanizing process, to impregnate wood
and other vegetable and animal substance, and thus
prevent their decay. Another important use of mer-
cury is found in the manufacture of barometers and
thermometers. It is especially adapted to the measure-
ment of heat, by its fluidity at low temperatures, and
its ready and equable expansion.
SILVER.
656. DESCRIPTION. — Silver is a lustrous
scription, ores white metal of perfect ductility and malle-
and solvents? abiljtVi Itg 1QSS Qf ]ustre QJ1 exposure, is
owing to the presence of a small proportion of sulphur-
etted hydrogen in the air. Nitric acid is its proper sol-
vent, though for certain purposes oil of vitriol is pre-
ferred. Silver is often found native, but moro fre-
quently combined with sulphur as silver glance.
Galena or sulphuret of lead always contains it in small
proportion, and sometimes to the amount of one or
two per cent.
How is silver && • PRODUCTION. — Silver is prepared
obtained? from the sulphuret, by first roasting the ore
SILVER.
263
with common salt, in order to convert it into chloride.
Iron is subsequently employed to remove the chlorine,
and isolate the metallic silver.
Give the com- 658. Mercury is added with the iron, in
piete process. orcjer ^^ jt may djssoive the silver from
the mass of roasted ore and iron, as fast as it is formed'
The materials are agitated with water for many hours
together. At the end of the process the mercury, with
its load of silver, is drawn off from the bottom of the
cask. The solution of silver in mercury is afterward
filtered through buckskin or closely woven cloth, which
allows a large part of the liquid metal to pass, while
the silver with a small portion of mercury is detained.
The silver is then freed of its remaining mercury by
heat. The above process is called amalgamation.
659. SILVER OBTAINED FROM LEAD. —
Describe the
process for Almost all lead, as produced from galena
and its other ores' contains a certain pro-
portion of silver. The latter metal may
be freed from a large part of the lead by melting the
alloy and then allowing it to cool slowly. Most of
the lead solidifies in small crystals, and may be skim-
med out with an iron cullender. An alloy containing
silver in large proportion remains in the liquid condi-
tion. It is afterwards solidified by further cooling.
The above is called Pattinson's process.
660. CUPELLATION. — The remainder of
How is the re- jeac[ js separated from the silver by con-
maimng lead
separated? verting it into oxide, in a current of heated
air. The silver does not oxidize under
these circumstances, but retains the metallic form.
264 METALS.
The mass of metal grows smaller as the process pro-
ceeds, till finally pure silver remains. The moment
of its production is indicated by a beautiful play of
colors and a sudden brightening of the metal. The
above process is carried on upon a hollowed and com-
pacted mass of bone-ash, called a cupel. The object of
the cupel is not alone to support the metal, but to ab-
sorb the hot and fused oxide of lead as fast as it is
formed. If a. little copper is present, it is also absorbed
with the lead. The process is called cupellation.
661. It may be illustrated on a small
How mcf/ the
process be u~ scale, by making an excavation in a piece
lustrated? Qf c[iarcoa]) an(j pressing into it a lining
of well burned and moistened bone
ash. A globule of lead, to which a little
silver has been added, is to be heated,
on the support, in the oxidizing flame.
For separating a small quantity of lead from silver,
the bone ash is not essential. The process may be
conducted before the blowpipe, upon the naked char-
coal. A small portion of silver may often be obtained
from the lead of commerce by this means.
What is said 662. SILVER COIN. — The standard sil-
of silver coins? ver of the United States is an alloy con-
taining ten per cent, of copper. Silver plate should
have the same composition. The object of alloying
with copper, is to impart greater hardness to the metal,
and secure against the gradual loss from attrition, which
would otherwise occur. Spanish silver often contains
a small proportion of gold. The gold is left as a black
SILVER. 265
powder, in dissolving such coins in nitric acid. Its
color and lustre may be brought out by rubbing.
663. THE SILVER ASSAY. — Assaying is
What is as- , n ,, . »
laying, and tne process by which the proportion of met-
why necessa- ais jn an a}}oy js ascertained. In all estab-
lishments where money is coined, assaying
is an important part of the work of the establishment.
The precious metals, as received at the mint, commonly
contain a certain proportion of other metals. But it
may be too much or too little. It is the business of the
assayer to ascertain its precise composition, that the
metal may be rendered purer, if necessary, or be fur-
ther alloyed, if found purer than the standard.
664. As a preparation for the silver as-
Descmbc the
process of as- say, a sample, containing an ounce, or other
definite weight of the impure metal, is dis-
solved in nitric acid. The dissolved silver has the pro-
perty of becoming solid again, and sinking
to the bottom of the clear solution as a white
curd, just in proportion as common salt is fur-
nished to it. But the other metals which
may be present, as impurities, have no such
effect. It follows, that the amount of silver
present, is just in proportion to the amount of
salt it is necessary to supply, before the pre-
cipitation, or formation of the curd, ceases. Now, the
assayer knows beforehand, how much salt he must
supply to the solution of an ounce of metal, if it be all
silver. If he finds that an ounce of the sample, re-
quires to be supplied with the same quantity, before the
precipitation ceases, he knows that the metal is all silver ;
12
266 METALS.
if but half as much is required, he knows that it is
but half silver. Having ascertained the true proportion,
the assay is completed. The salt required in the pro-
cess is employed in the form of a solution, and the
quantity used is known by pouring it from a graduated
vessel.
665. EXPLANATION. — The curd, which
Explain the
chemical ac- forms in the above process, is insoluble
abovTprocess. chloride of silver, formed from the silver of
* the solution, and the chlorine of the salt.
The nitric acid and oxygen, which were combined
with the silver, at the same time unite with the sodium,
forming nitrate of soda, which remains in solution.
666. SILVER SEPARATED FROM COPPER.
Describe the ,•••/.
method of ex- Copper, obtained from certain ores, con-
tams so mucn silver as to make their separa-
tion an object of importance. The method
pursued is, to fuse the copper with lead. As the lead
flows out again by subsequent fusion, it brings with it
all the silver, and the copper remains behind as a spongy
mass. This process is called liquation. The silver is
then freed from lead by the process of cupellation al-
ready described.
Mention some ^67. IfsES OF SILVER. Most US6S of
uses of silver, silver are so familiar that they need not be
here mentioned. Its employment for daguerreotype
plates depends on the fact that the color of many of
its compounds is readily changed by light. This sub-
ject is more fully considered in the section on chlo-
rides. The nitrate of silver, or lunar caustic, is used
in surgical operations, to burn or cauterize the flesh.
GOLD. 267
In solution, it is also employed as a hair dye, and in
the production of indelible ink.
GOLD.
Mention some 668. DESCRIPTION. — Gold is a yellow
properties of metai of brilliant and permanent lustre.
gold? Its sol- ±
vent? and Its extreme malleability is strikingly illus-
occurrence?
into a leaf but little more than ¥^J¥¥¥ of an inch in
thickness. As the fact may be otherwise stated, a cube
of gold, five inches on a side, could be so extended as
to cover more than an acre of ground. Such gold leaf
is permeable to hydrogen. A jet of this gas may be
blown through it and kindled on the opposite side.
Gold is proof against all ordinary acids, excepting aqua-
regia. It is found only in the metallic state, and com-
monly either in quartz rock or in the sands of rivers.
Native gold contains from five to fifteen per cent, of
silver.
How is pure ^69. PRODUCTION. - THE REFINING PRO-
goid produced? CESS. — Native gold may be freed from the
silver which it contains, by the agency of concentrated
sulphuric, or nitric acid. A difficulty in accomplishing
this result arises from the fact that every particle of silver
is so perfectly surrounded by gold, that the acid does
not readily reach it. This difficulty is overcome by
fusing more silver into the gold, and thus opening a
passage for the solvent. This being done, both the
original silver and that which has been added, are read-
ily removed. The above is the process at present pur-
sued in France for refining gold.
268 METALS.
Describe an- 670. ANOTHER METHOD. The SGCOIld
other method. method is essentially the same as that al-
ready described, with the substitution of nitric for sul-
phuric acid. The addition of silver, as a preliminary
step, is found necessary in this process also. So much
silver is added, that the gold forms but a quarter of the
mass exposed to the action of the acid. The method
is hence called quartation. * The process involves a
previous knowledge of the approximate composition
of the mixed metal. This may be obtained by the
touchstone, as hereafter described.
Whatisamal- 671. AMALGAMATION. — Gold may be ob-
gamation? tained from any material which contains
it, even in small proportion, by the process of amalga-
mation. This process consists in agitating the finely
divided material with mercury, until the latter has ex-
tracted all of the precious metal. It is then obtained
from its solution in mercury, by the same means em-
ployed in the case of silver. This method is employed
in the case of the gold-bearing quartz of California.
The dust of jewelers shops is similarly treated, in order
to save the small proportions of gold which it contains.
672. GOLD FROM LEAD AND COPPER. —
How is gold .
separated Certain ores of lead and copper contain so
much §old that it; is Profitable to extract it
from the metal which they yield. This
is done by the processes of liquation and cupellation be-
fore described.
* In the practice of the United States Mint, the addition of less
silver has been found sufficient. The proportion of gold is there
reduced to one-third. Nitric acid is then employed in the refining
process.
GOLD. 269
673. GOLD FROM STJLPHURETS OF IRON,
How is qold ci i i f • e
obtained from &c.— Sulphurets of iron, copper, dec.,
certain ml- sometimes contain gold, in small quantity,
and so completely disseminated that it can-
not be readily extracted by mercury. It has been found
advantageous to heat such ores with nitrate of soda,
previous to amalgamation. The sulphurets are thus
partially converted into sulphates, which can be washed
out. What remains of the pulverized material is at
the same time thoroughly opened to the action of mer-
cury.
Describe the 674. THE GOLD ASSAY. — Gold to be as-
method of 'as- saye(j contains commonly, only silver and
saying gold ? . . . ' ' /
Why is siher copper, as impurities. By msing the sam-
ple with lead, and then removing this
metal by cupel! ation, it carries with it the copper, into
the cupel. A globule, containing only gold and silver,
remains. The silver is then dissolved out by nitric
acid. The remaining sponge of pure gold being
weighed, and its weight compared with that of the orig-
inal sample, the assay is completed. More silver is
added in the process, for reasons stated in a. previous
paragraph.
What is the 675. ASSAY OF GOLD BY THE TOUCH-
touckstone? STONE. — Any hard and somewhat gritty
and how ts it J J
used in assay- stone, of a dark color, which is not acted
on by acids answers the purpose of a touch-
stone. The assay consists in marking upon the stone
with the alloy, and judging of the purity of the metal
from the color of the mark, and the degree in which
it is affected by an acid. Nitric acid, to which a very
270 METALS.
small quantity of muriatic acid has been added, is em-
ployed in this test. Gold alone is proof against its
action. In proportion to the permanence of the mark,
is the purity of the gold which has been submitted to
the assay.
What is said 676. GOLD COIN. — The gold employed
of gold coin ? for CQ^ plate and je weiry js a] ways alloyed
with a certain portion of copper or silver, to give it
greater hardness. The standard gold of the United
States is nine-tenths pure gold, the remaining tenth
being an alloy of copper and silver.
677. PURITY OF GOLD. — The purity of
How is the de- .
gree of purity gold is expressed in carats •, a carat signify-
mwMdr ing' Practicall7> one twenty-fourth. Thus,
when gold is said to be sixteen carats fine,
it is meant, that two-thirds of it is pure gold. Gold
eighteen carats fine is three-fourths pure gold, and one-
fourth alloy.
678. GILDING. — Gilding by the galvanic
How is copper
jewelry gild- battery has been already described. This
method is, in most cases, preferable to all
others. Copper jewelry is thinly gilded by boiling in
a solution of gold in carbonate of soda or potash. The
solution is prepared by first dissolving the gold in aqua
regia, and afterward precipitating and re-dissolving it,
by means of the carbonate above named.
679. Gildine may also be effected by an
Describe the ° J
method of gild- amalgam of gold and mercury. The amal-
omof am/ £am ^em§ applied, the mercury is expelled
by heat and the gold remains. This me-
thod is very frequently employed. A coating of pure
PLATINUM. 271
gold is produced upon articles of jewelry, made of im-
pure metal, by first heating them, and then dissolving
out the copper by means of nitric acid.
PLATLNTJM.
680. DESCRIPTION. — Platinum is the
Platinum —
Description, last of the noble metals. It resembles
^sofoentsT' Stee^ m c°l°r> anc^ possesses a high degree
of malleability. It is the heaviest and the
most infusible of all metals. At a white heat it may
be welded, like iron. Like gold, it resists the action
of any single acid, but may be dissolved in aqua-regia.
It is commonly found, like gold, in small flattened
grains, in the sand of certain rivers. Its pecuniary
value is about half that of the more precious metal.
681. PLATINUM CONDENSES GASES. — The
Mention a re-
markable ef- metal platinum has the remarkable pro-
PeriY of condensing gases upon its surface,
and thereby increasing their affinities.
This effect is in proportion to the surface
exposed. It may be prepared for this experi-
ment by burning paper, previously moistened
with a solution of this metal. Such an ash,
by simple exposure to the air, condenses and
retains a large quantity of oxygen within its
pores. On holding it in a jet of hydrogen,
the condensed oxygen immediately unites with the
latter gas so energetically as to inflame it.
682. Platinum is employed for similar
Give another
illustration of purposes, in the form of a sponge, and as a
this effect. powder, called p latinum black. A mixture
272 METALS.
of nitric oxide and hydrogen, passed through a tube con-
taining heated platinum black, issues from the tube as
ammonia and water. The hydrogen has entered into
combination with both of the elements of the nitric
oxide, producing two new compounds.
Why isplati- 683. OTHER USES OF PLATINUM. — The
num. superior m0st important use to which platinum is
to ot her metals _ .
for chemical applied in the arts, is in the manufacture
apparatus? o^ ^Q^^I apparatus. Its extreme in-
fusibility and resistance to acids, adapt it especially to
this purpose. In the manufacture of oil of vitriol, for
example, no other material excepting gold could well
take the place of the platinum vessels, in which con-
centration is effected. Platinum crucibles are also in-
valuable, as they may be exposed to the fire of a blast
furnace without injury. Nothing less than the most
intense heat of the oxyhydrogen blow-pipe, or galvanic
battery, is sufficient to fuse this metal.
ALLOYS.
. 684. The compounds of metals with
alloy? Give metals are called alloys. The following
fiontfPb°rasS are among the more important.
and other al- Brass is copper, lightened in color by
the addition of one-fourth its weight of
zinc.
German silver is a kind of brass, still further whitened
by nickel. Its exact composition has been given in
another place. An alloy of 30 parts silver, 25 of nickel,
and 55 of copper forms a nearly perfect substitute for
silver for all ornamental purposes.
ALLOYS. 273
Bronze is copper, containing ten per cent, of tin.
Bell metal is a kind of bronze, containing tin in larger
proportion.
Pewter is an alloy of tin with variable proportions
of antimony or lead. Britannia ware, so called, is a
sort of pewter.
Type metal is an alloy of lead, containing twenty-
five per cent, of copper. By the use of tin, instead of
lead, a better, but more expensive type metal may be
produced. Zinc, with a few per cent, of copper, lead,
and tin, has also been recently employed.
Fine and coarse solders are alloys of tin and lead
the former being two-thirds, and the latter one-fourth,
tin. Hard solder is a variety of brass.
Newton's fusible metal, which has the remarkable
property of melting in boiling water, is composed of
8 parts of bismuth, 5 of lead, and 3 of tin.
Many of the above alloys are slightly varied in
their character by the addition of other metals in small
quantity.
274
SALTS.
CHAPTER III.
SALTS.
SOLUTION AND CRYSTALLIZATION.
„„ , 685. DEFINITION. — Under the general
What com-
pounds are head of salts, are included all compounds
of acids and bases, and beside these, the
compounds of chlorine, bromine, iodine, sulphur, &c.
with the metals. Sulphate of soda, or blue vitriol, is
an example of the first class, and chloride of sodium,
a common salt, of the latter.
686. PREPARATION or SALTS. — The salts
Mention some
methodsofpre- of most acids may be produced, by sim-
paring salts ? ^ brmgmg tne acid and oxide together.
Sulphate of potassa is thus produced, from sulphuric
acid and potassa. Heat is sometimes required, to bring
about the combination. They may also be prepared
from the carbonates. Thus acetate of lime, is pro-
duced by pouring strong vinegar on chalk, or carbo-
nate of lime. Carbonic acid is, in such cases, expelled
by the stronger acid which is employed. Other meth-
ods of preparing individual salts, will be hereafter
given.
Explain solu- 687. SOLUTION. — The particles of all
tion. bodies are held together, as before ex-
plained, by the attraction of cohesion. But water has
SOLUTION. 275
also an attraction for these particles. In the case of
many substances, it overcomes the force of cohesion
and distributes them throughout its own volume.
Such a distribution, in which the solid form of the
solid is entirely lost, is called solution. Different
liquids are employed, as solvents for different sub-
stances. A solution is said to be saturated when no
more of the solid will dissolve in it.
688. PRECIPITATION. — In solution, the
Have the par-
ticles lost their particles of bodies have not lost their
TractionThoio property of cohesive attraction. It is only
may they be overcome by a superior force. As soon as
precipitated ?
this is weakened, they unite again to form
a solid. The solvent power of alcohol for camphor, is
thus diminished when water is added to the solution.
As a consequence, the camphor immediately re-
assumes the solid form. When a solid is thus
re-produced as a liquid, it is called a precipit-
ate. The above experiment is made, by ad-
ding water to an ordinary solution of camphor.
689. One case of precipitation is men-
Mention two . i • i T
general mcth- tioned m the preceding paragraph. But it
ods of precip- mav ^e effected by various methods. All
ttation f *
of these may be arranged under two heads ;
precipitation by changing the character or quantity of
the solvent, and precipitation by changing the sub-
stance dissolved.
Mention three 690. CHANGE OF SOLVENT. The three
'b' cases in which precipitation is effected by
ye of sol- changes in the solvent, are, mixing, cooling,
and evaporation. The first has just been
276 SALTS.
described. The second is illustrated in the production
of alum crystals, by cooling a hot solution. The third
consists in dissolving a solid in some liquid, and then
boiling away the latter. The experiment may be tried
with a saturated solution of salt and water. As fast as
the water is boiled away, the portion which has lost its
solvent, re-assumes the solid form.
691. CHANGE OF SUBSTANCE DISSOLVED.
Describe two , . , , .
cases by The change in the substance dissolved, is
Stance' °^ mb' effected? in some cases> by addition, and in
others by subtraction. Carbonic acid,
blown through lime water, precipitates it, by addition.
The precipitate is chalk, or carbonate of lime. Pot-
ash, added to a solution of sulphate of copper, precip-
itates it by subtraction ; the precipitate is oxide of
copper, deprived of its acid by the potash.
692. EXPLANATION. — The above cases
State the cause f . . , ~
of predpita- of precipitation, demand some further ex-
hon. m the planation. As fast as carbonic acid is blown
above cases.
into the lime water, in the first case, the
new substance, chalk, or carbonate of lime, is produced
throughout the liquid. We may suppose that innume-
rable particles are first formed, before they unite to
form a precipitate. But the cohesive attraction put
forth by the particles of this new compound is so great
that the opposing attraction of the water is overcome,
they rush together, and assume the solid form of a pre-
cipitate. This did not happen in the case of lime alone,
because the cohesive attraction between its particles is
inferior to the opposing attraction of the water. The
second case is to be similarly explained.
COHESION. 277
693. RELATION OF COHESION AND AFFIN-
What is said
of the relation iTY. — The chemical affinity of potassa for
"/ndaffinit ? carbonic acicl, is evidently greater than that
of lime. The former base retains the acid
so firmly, that no degree of heat can effect it, while
the latter gives up its acid with readiness, under the
influence of a high temperature. Notwithstanding the
superior affinity of potassa, lime will take from it, its
carbonic acid, if added to a solution of carbonate of
potassa, in water. The mixture being made, the par-
ticles in this and in all similar cases, tend to re-arrange
themselves in the solid form. They seem to do this
without reference to their chemical affinities, in such a
manner as best to resist the solvent action of the water,
or other liquid. Carbonate of lime resists such action
better than carbonate of potassa. The former is there-
fore produced. The cohesion of carbonate of lime,
using the term, in the sense of capacity to resist the
separating power of water, has therefore determined
the production of this substance, in opposition to or-
dinary chemical affinities,
694. The above case illustrates a gene-
Statc and il-
lustrate the ral law. Two substances, which when
general law? Qnite(j form an insoluble compound, gen-
erally unite and produce it, when they meet in so-
lution. To illustrate by another example : phos-
phate of lime, or bone ash, is insoluble. Then
we may be sure that phosphoric acid and lime, if
brought together by mixing two solutions, will de-
sert any substances with which they were before
combined, and unite to form insoluble phosphate of
12*
278 SALTS.
lime. This rule is not without exceptions, but it
enables the chemist to determine beforehand innume-
rable cases of precipitation.
695. SOLUTION AND CHEMICAL COMBINA-
tion differ TioN. — Solution differs from chemical com-
bination in tne varying proportions in
which it occurs according to tempera-
ture, and in the absence of any change of chemical
properties. Nitre, for example, dissolves in water, at
100°, in nearly double the quantity which will dis-
solve at 70°. At the same time, it forms a solution to
which it has imparted its own chemical properties
unchanged.
596. Another important distinction is
State another ,
important found in the following fact. While chem-
twn' ical combination is most active between
bodies whose properties are most opposed, such as fat
and resins, solution occurs most readily in the case
of similar substances. The metals dissolve in mer-
cury. Salts dissolve in water. Fats and resins dissolve
in alcohol and ether, which, like themselves, contain
much hydrogen.
697. CRYSTALLIZATION. — In passing from
What is said ,r
o/ crystalline the liquid to the solid condition, the par-
arrangement? ^^ Qf mogt bodieg assume a crystalline
arrangement. Their mutual attraction is more than
a mere force which draws and binds them together.
It groups them in regular forms. The crystals thus
produced are often too small to be separately seen. But
even where this is the case, the crystalline structure is
readily observed. Surfaces of zinc, or cast iron, ex-
CRYSTALS.
279
How may
'
posed by recent fracture, are familiar examples. But
where the circumstances are favorable for the forma-
tion of individual and separate crystals, the most beau-
tiful and symmetrical forms are often the result.
698. PRODUCTION OF CRYSTALS. — Most
.
of the salts to be described in this cnap-
produced? ter may be 0^^ jn tne form of crys-
tals, by evaporating or cooling their saturated
solutions. The method by cooling, has already
been described, in the Chapter on Water. In
obtaining crystals by evaporation, the solution
is to be moderately heated, in a saucer or other
vessel. The crystals formed by either method,
commonly contain water, which becomes part of
the solid crystal, and is called water of crystalliza-
tion.
699. VARIETY OF CRYSTALS. — The forms
of leaves and flowers are scarcely more va-
rious than those of crystals. The latter are,
as it were, the flowers of the mineral world,
as distinctly characterized in their peculiar beauty as
the flowers that bloom in the air above them. Even
where color fails, the eye of science distinguishes pe-
culiar features which often enable it to determine the
nature of a substance, from the external crystalline form
which it assumes.
1234 5
How may the
variety of
crystals be il-
lustrated ?
280 SALTS.
What is said 700' FoRMS OF CRYSTALS.—AS every
of the variety flower has its own distinctive form of
of forms in a . , .
single sub- leaves and petals, so every substance has
its own form or set of forms from which it
never essentially varies. Among these, or its combi-
nations, it is, as it were, left free to choose in every
crystal which it builds. The mineral quartz, which
caps its prismatic palace with a hexagonal pyramid, is
an example. Its common form represented in Fig. 4,
is a combination of the prism and double six-sided py-
ramid, which commence the series.
701. A form similar to the double six-
D escribe some
forms of a sided pyramid, with faces corresponding to
single set. -^ twejve converging edges, belongs to the
same set. Double pyramids similar to each of these, but
of one-half or one-third their relative height, or differing
from them by some other simple ratio, also belong to
the same set of forms. Fig. 3 represents a form com-
posed of two of these pyramids. Fig. 5 represents
another form in which one of them is modified by two
faces of a prism. To all of these and certain other in-
timately related forms, the imaginary privilege of se-
lection and combination, above referred to, extends.
But most substances, like quartz, as above described,
affect some particular shape or combination in which
they usually appear.
702. MODIFICATIONS OF CRYSTALS. —
What modifi- _ ...
cations of the Whatever the form or combination may be,
may occur? ^ *s su806?^6 of variation, in any degree,
so long as its angles correspond to those of
the perfect shape. Thus the mineral quartz, in its
CRYSTALS. 281
commonly occurring combination, is not restricted to a
perfectly symmetrical shape, like that above presented.
It may develop one surface and diminish the others to
any extent. Forms such as
are represented in the margin
result. Different as they seem,
it will be observed that they
agree precisely with the per-
fect shape in the angles be-
tween the surfaces of the prism and pyramid, and the
different surfaces of each. In this their identity
as crystalline forms consists. It would thus seem that
nature pays exclusive attention to the corners and an-
gles in her various systems of crystalline architecture.
703. The least variation of the relative
What consti- ..... ,
tutes a new length of the vertical axis that is not by
some simple ratio, constitutes a new and
distinct form. This has its related forms as before,
the whole making a new and distinct set, to which the
choice of any substance that enters it, is limited.
704. SYSTEMS OF CRYSTAL FORMS. — It
Define ano-
ther system of will be obvious to the student that the sub-
CformsliUe stitution of an octahedron, such as is re-
presented in the accompanying figure, for
the double six-sided pyramid, would be the
starting point, of an entirely distinct system of
forms. Within its limits there might be in-
numerable sets as before. It would be, as it
were, the type of a new order of crystalline architec-
ture, susceptible of variations consistent with the ge-
neral style.
282
SALTS.
Define the 705. A third system is characterized by
fourth^ inequality in three principal dimensions.
systems. The axis or lines connecting the solid an-
gles in the octahedron, and joining the faces in the
prism, are all unequal. As each axes may be indefi-
nitely varied in this system, there is room wthin its
limits for still greater variety than before. The fourth
system differs from the third in an oblique position of
some one of the unequal axes. The student will
readily imagine certain oblique forms which it in-
cludes. The fifth system is characterized by an ob-
lique position of three unequal axes.*
706. The regular system, which is pro-
What are the f
characteristics perly the first, has all its axes equal, and all
°/ystkemTUlar its angles right angles.f The figures
which precede this paragraph, represent
some of its simpler forms. Those which follow, are
among its most interesting combinations. In the
last, the student will be able to select three distinct
kinds of surfaces. One of these sets, if enlarged to
the exclusion of the others, would produce a cube,
* The variations of length and inclination of axis which correspond
to the different systems, may be beautifully illustrated to the eye by a
wooden frame work movable at the centre with threads connecting
the arms.
f The first and sixth systems are made to change places in the above
ai'rangement, for the convenience of illustration, from the quartz crystal.
CRYSTALS. 283
another a regular octahedron, and a third a dodecahe-
dron ; forms corresponding to those of the preceding line.
In view of its simplicity, the regular system may be
regarded as a sort of primitive architecture, yielding,
however, to no other system in the beauty of its forms.
Under one or the other of these systems all forms of
crystals are included. To each of them, with the ex-
ception of the last, belong innumerable sets of forms
according to the degree of inequality or inclination of
the axes. Equality and rectangular position of the axes
being characteristic of the first system, it is not suscep-
tible of the sort of variation which is essential to pro-
duce different sets of figures. But in this, as in other
systems, the modification of surfaces may occur to any
extent.
„, , ,, 707. As the architect is able, from some
bn.ow now trie
formofacrys- relic of a broken column, to build up in
ferr^ifrom, imagination the temple of which it formed
its angles. a part . as the comparative anatomist knows
how, from the fragment of a single bone to reconstruct
in imagination the perfect animal which possessed it ;
so, from the merest point of a crystal, its complete form
may often be readily inferred. In proportion as a dou-
ble pyramid is lengthened out, the angles above arid
below are rendered more acute. Prom an accurate
admeasurement of this angle its whole shape may there-
fore be inferred. Such admeasurement of various an-
284
SALTS.
gles is employed not alone as a means of inference of
perfect from imperfect shapes, but as the simplest means
of accurate description. For, as before stated, it is the
size of the corresponding angles of a crystal which
form its characteristic.
Have different 70S. ISOMORPHISM. — Many substances
substances ever whi(jh are aljke in ^ ,mmber and arrange.
Iflv SGL-iflv CTlj&m ^
tallineform? ment of their atoms, although these atoms
are different in kind, have the same crystalline form.
This is the case with common alum, and other alums
to be hereafter mentioned. The similar arrangement
of atoms will be best seen by inspecting the formulas
which represent them. These are given in the appendix.
The term expresses their likeness in form. Besides
this series there are many other isomorphous groups.
Give the pro- 709. It is to be regarded as probable,
babie reason. that faQ snape and size of the molecules
thus similarly composed, is exactly the same, and that
it is for this reason that they may be used in building
up crystals of the same form. The different alums will
even unite when they crystallize, in building up one
and the same crystal. Substances which are thus si-
milar in composition, and crystallize in the same form,
are called isomorphous. There are many cases of simi-
lar crystalline form in substances which are not thus
related in other respects. Such bodies are not called
isomorphous, notwithstanding their identity of crys-
talline form. Certain substances crystallize in forms
belonging to two or even three different systems, ac-
cording to the temperature, or other circumstances
under which their crystallization occurs. Such sub-
stances are called dimorphous or trimorphous.
OXIDES. 285
OXIDES.
Define an ox- 710. The compounds of the metals with
terms ere- oxygenj with tne exception of those which
ferent oxides have decided Iv acid properties, are called
distinguished? _„ J
oxides. When a metal unites with oxy-
gen in several different proportions, forming different
oxides, these a"re distinguished as protoxide, deutoxide
or binoxide, tritoxidc or teroxide : terms signifying
first, second, and third ^oxides. The highest oxide is
also called peroxide. An oxide containing three atoms
of oxygen to two atoms of metal, is called a sesquiox-
ide. The names of chlorides, sulphurets, &c. are simi-
larly modified, to indicate the proportion of chlorine,
sulphur, &c. which they respectively contain. Com-
pounds of non-metallic substances with oxygen which
do not possess acid properties, are also called oxides.
There are, for example, oxides of nitrogen and phos-
phorus.
711. PROPERTIES OF OXIDES. — The
What is said
of add and lower oxides are generally strong bases,
basic proper- w^{\e tne higher oxides exhibit basic or
tics in oxides ?
acid properties, according to circumstances.
Binoxide of tin, for example, described in a previous
chapter, acts as a base in combining with sulphuric
acid to form 'a sulphate, while, if fused with potassa, it
acts as an acid, and forms a stannate. On account of
its acid property, the binoxide of tin is also called stan-
nic acid. The name is derived from Stannum, which
is the Latin word for Tin.
286 OXIDES.
712. FORMATION OF OXIDES. — Oxides
How are ox-
ides formed? may be formed directly by the union of
Give exam- oxygen and metal, or, indirectly, by sepa-
rating them from some salts which con-
tain them. Thus oxide of copper may be produced
by simply heating copper in the air ; or, by precipita-
tion from the nitrate, through the agency of potassa,
or, thirdly, by simply heating the nitrate till all the
acid is expelled. The oxides of tin and antimony are
also directly produced, by the action of nitric acid on
the metals.
What is a hy- 713. HYDRATES, OR HYDRATED OXIDES.
drated oxide? Oxides commonly combine in the act of
precipitation with a certain proportion of water. The
compound thus formed, are called hydrated oxides, or
simply hydrates. The water may, in most cases, be
separated from them by heat, and the uncombined
oxide thus obtained.
714. CONVERSION OF OXIDES. — When
What is said .
of the conver- oxides are converted into chlorides, sul-
sionof oxides? phuretgj ^ by double decompositions, to
be hereafter described, the chlorides, sulphurets, &c.,
correspond to the oxides from which they are formed.
Thus, protoxide of iron yields protochloride, while ses-
quioxide yields sesquichloride.
715. THE ALKALIES. — The oxides of po-
Give some .
properties of tassmm and sodium are called alkalies.
the alkalies. They are known as potassa and soda,
and are commonly obtained as hydrates. They are
white infusible substances, from which the water
cannot be expelled by heat. They are soluble in water,
POTASSA. 287
and are the strongest of all bases. From their destruc-
tive action on animal matter, they are called caustic
alkalies, and are often distinguished, by this term,
from the carbonates of potassa and soda.
POTASSA.
716. Potassa is prepared from wood
What is the
source of po- ashes. The ley obtained from these be-
ing evaporated to dryness, the mass which
remains is the crude potash of commerce. This, when
purified, becomes pearlash.
How is potassa 717. CAUSTIC POTASSA. — Commercial
prepared? potash and pearlash are both carbonates
of potash, from which the carbonic acid must be
removed, in order to produce potassa itself. This is
done by a milk of slaked lime. A solution of potash,
in at least ten parts of hot water, or a hot ley, made
directly from wood ashes, should be employed in the
experiment. To this, the milk of lime is added, little
by little, the solution boiled up after each addition,
and then allowed to settle. If, after settling, a por-
tion of the clear liquid is found no longer to effervesce
on the addition of an acid, it is sufficient evidence
that all the carbonic acid has been removed by the
lime, and the process is completed. This must be as-
certained by trial. About half as much lime as pot-
ash will be required in the process. Caustic soda is
similarly made from the carbonate of soda.
718. The boiling in the above process
Give a modi-
fication of the may be omitted, if the mixture be fre-
above method. quent]y shaken up, during several days.
288 OXIDES.
This modification of the method is much the most
convenient for the production of caustic al-
kalies in small quantities. Solutions, useful
for a variety of chemical purposes, are thus
obtained, and should be preserved for use.
They may be converted into solids, by
evaporation, and the solid thus obtained fused
and run into moulds. The commercial caustic
potassa, occurring in slender sticks of white
or grey color, is thus produced.
719. AFFINITY OF POTASSA FOR WATER.
How can the
affinity of po- Ordinary potassa, as before stated,
is a hydrate- But its affinity for
water, is by no means yet satis-
fied in this form. If exposed in an open
vessel, it rapidly attracts moisture from the
air. It often dissolves, in the course of a few days, in
the water thus obtained.
720. DECOMPOSITION BY POTASSA. — Po-
What is said .
of the decom- tassa added to the solution of almost
Ps°aitsTypfo- any salt> occasions a precipitate. The
tassa? potassa takes the acid, and precipitates the
insoluble base. If the experiment be made with an
ammonia salt, the base being volatile, passes off into
the air. Experiments may also be made with green,
blue, and white vitriols, which are, respectively, sul-
phates of iron, copper, and zinc. ,
721. CLEANSING AND CAUSTIC PROPER-
«EB OF PoxAssA.-If soiled rags be boiled
perties of po- with a dilute solution of potassa, they will
be thoroughly cleansed by the process.
POTASSA. 289
The potassa unites with the acid of the grease con-
tained in the cloth, and thus makes it soluble in water.
722. ACTION OF POTASSA ON ANIMAL
What is the
action of po- MATTER. — Potassa is extremely destructive
^al matter />" of animal matter. It readily dissolves the
skin, as may be proved by rubbing a little
between the fingers. If applied in sufficient quantity.
it destroys the vitality of the flesh. It is often used
for this purpose by surgeons.
723. EFFECT ON VEGETABLE COLORS. —
How does po-
tassa affect vc- Vegetable blues which have been pre-
getabie colors? viously reddened by acid, are restored to
their original color by the action of potash and other
alkalies. The blue pigment called litmus is the one
most readily obtained. In preparation for the exper-
iment it is infused in hot water The transformation
from blue to red, and vice versa, may be repeated as
often as desired, by the alternate addition of acid and
alkali. Paper soaked in the red and blue liquids
forms the test-paper of the chemist. It is used to in-
dicate the presence of smaller quantities of acid and
alkali than could be recognized by the taste. An extract
of purple cabbage leaves, or the leaf itself, may be
used in the above experiment. In this case, the change
of color by alkalies is from red to green.
724. PROPERTIES OF SODA. — The prop-
of erties of soda, are very similar to those of
potassa, as above described.
13
290 OXIDES.
OXIDE OF AMMONIUM.
725. FORMATION. — When hydrated
WJiatissaid . .
of oxide of sulphuric acid combines with ammonia,
ammonium? tne water which it contains is regarded
as converting the ammonia into oxide of ammonium,
with which the acid then combines. The action of
other hydrated acids is the same. In naming the cor-
responding salts, the oxide of ammonium is called
ammonia. Thus, the compound with sulphuric acid,
is called sulphate of ammonia. It is to be borne in
mind, that oxide of ammonium of such salts, contains
an atom of water, in addition to the constituents of
ammoniacal gas.
OXIDE OF CALCIUM.
How is lime 726. LIME. — Lime or oxide of calcium
obtained? is best obtained by heating chalk, marble
or limestone. These are all carbonates of lime. Under
the influence of a high temperature, the tendency of
the carbonic acid to assume the gaseous form is so
increased, that the chemical affinities of the base are
overcome. The carbonic acid escapes, leaving the caus-
tic lime behind. This is the process of the ordinary lime
kiln. The superior strength of potassa and soda, as
bases, is illustrated by the fact that the carbonic acid
cannot be removed from them through the agency of
heat.
TO* , • , ^27. HYDRATE OF LIME. — SLAKED LIME.
What is hy-
drate of * When water is added to lime, one equiva-
^^me? jent jmme(jiate]y combines with it, and
LIME. 291
forms a hydrate. The hydrate, like that of potassa, is
dry, although it contains a large portion of combined
water. As the water thus becomes solid in the com-
pound, its latent heat is given off to the air or sur-
rounding objects. The employment of heat thus pro-
duced for culinary operations has been recently sug-
gested. If the process of slaking be conducted
under a tumbler, with a slight surplus of water, steam
will be produced. On lifting the tumbler, it will be-
come visible by its condensation into vapor.
728. IGNITION BY LIME. — The heat
How may gun-
powder be iff- thus produced, is often sufficient to ignite
Ik^en^of gun-powder. It should be sprinkled on
lime? the mass, and kept dry while the slaking
proceeds. Warm water and well-burned lime should
be employed in the experiment.
729. ACTION OF THE AIR. — If lime is
What is the
action of the exposed to the action of the air, it gradu-
aironlime? cart)Onic acid and
water, and becomes converted into a mixture of hydrate
and carbonate. It is then called air-slaked lime. By
sufficiently long exposure the conversion into carbo-
nate is complete.
730. LIME IN MORTAR. — Ordinary mortar
mortar har- is a mixture of sand and lime. It hardens
not simply by drying, but by the absorp-
tion of carbonic acid from the air. A compound of
hydrate and carbonate of lime, possessed of great hard-
ness, is thus produced. A gradual combination, also
takes place between the silica and the lime, which
binds the two constituents still more firmly together.
292 OXIDES.
731. HYDRAULIC CEMENT. — If, in the
WJiat is liy-
drauic ce- preparation of lime, a limestone is used
which contains a certain proportion of
clay, a double silicate of alumina and lime is produced.
The compound has not alone the property of combi-
ning with water, like ordinary lime, but of becoming
extremely hard and insoluble in the process. Such a
lime is called hydraulic cement, and is used for building
under water. Silica, magnesia, and some other sub-
stances impart the same property to lime.
ALUMINA, MAGNESIA, (fee.
Whatisalu- 732. ALUMINA, &c. — Alumina, so named
mina' from the corresponding metal, is insoluble,
and is called an earth. It is, like the peroxide of iron,
a sesquoxide, containing three atoms of oxygen to two
of metal. Natural alumina, colored blue, is called sap-
phire. Colored red, it forms the oriental ruby. The
topaz and the emerald are also compounds containing
the same oxide. Baryta, strontia, lime and magnesia,
are regarded as standing midway between the earth
alumina and the alkalies, and are called alkaline earths.
They are more or less soluble, and possess the general
properties of the alkalies, in a diminished degree.
Magnesia is sometimes classed as an earth.
733. OTHER METALLIC OXIDES. — The
What are the
properties of remaining metallic oxides are powders of
lalh°foxiL% different colors. Most of them are insol-
uble. The more important have been
already noticed, in the Chapter on Metals. Their
OXIDES. 293
hydrates may be obtained by precipitating solutions
of their salts with potassa, soda, or ammonia. The hy-
drate of the oxide of copper, and peroxide of iron,
may serve as examples. The former is blue and the
latter a reddish brown.
734. The hydrated oxides of nickel, co-
ted oxid™ dis- bait, tin and copper, produced from soliu
soiveinam- tion of these metais by the addition of
moma ? J
ammonia, are again re-dissolved in an
excess of ammonia. That of copper dissolves with a
beautiful blue color, which is conclusive evidence that
the liquid with which the experiment is made contains
copper in solution.
735. USES. — Oxide of magnesium or
Give the uses
of some of the magnesia, and mercury, among others, are
oxide* ? used in medicine, and white oxide of zinc,
as a paint. Litharge or protoxide of lead is employed
in making flint-glass and varnishes. Red lead is used
as a paint. Oxide of bismuth is employed as a cos-
metic.
736. Oxide of manganese is used to
C°lor laSS U1'le aild Vi°let Oxide °f
glass by the cobalt, to color it blue : oxides of copper,
oxide of man-
ganese, cobalt, and chromium, to impart a green color to
CdxpC&c 7°n' £lass and Porcelaitl j peroxide of iron,
to give it a yellowish red, and protoxide, a
bottle-green. Sub-oxide of copper gives to glass a
beautiful ruby red. Silver and antimony are employed
to produce different shades of yellow and orange. Vi-
olet and rose color, are obtained by means of the purple
of cassius, a beautiful purple precipitate, containing
294 CHLORIDES.
tin and gold, and obtained by adding protochloride of
tin to a gold solution.
737. GLASS STAINING. — The effect of
effects be illua- oxides, above mentioned, in coloring glass,
trated? mav ^Q jnustrated by fusing them into a
borax bead. The bead is to be formed with the
aid of the blow-pipe, in a loop of platinum wire.
In the absence of such wire, the borax glass
may be made upon the surface of a pipe bowl. In-
stead of employing the oxide, it is generally more
convenient to moisten the bead with a very small
quantity of a solution of the metal. In order to obtain
good colors, the quantity of coloring material employed
must be very small.
738. For staining glass and porcelain su-
and porcelain perficialiy, a colored and easily fusible
SlaSS 1S fil>St PrePared with borax Or S0me
analogous material. This being ground
up and applied as a paint, is afterward baked into
the surface. Several of the oxides mentioned in a pre-
ceding paragraph are thus employed.
CHLORIDES.
739. DESCRIPTION. — The chlorides are,
Describe some
of the proper- for the most part, soluble salts, of colors
corresponding to the solutions of the metals
from which they are produced. Common
salt may stand as a type of the class. The
chloride of silver, subchloride of mercury or
calomel, are insoluble, and the chloride of lead
but slightly soluble in water.
CHLORIDES. 295
740. PREPARATION. — Chlorides may be
How are chlo- , , . . ., , , . ,
rides made made by the action of chlorine or hydro-
chloric acid on the metals. The combus-
tion of antimony in chlorine gas, the solu-
tion of gold in aqua regia, and that of zinc in hydro-
chloric acid are examples. The chemical action in each
of these cases has been explained in previous chapters.
The solutions being evaporated, the chlorides are ob-
tained in the solid form. The solution of zinc in hy-
drochloric acid is a case of single elective affinity:
the metal elects or chooses the chlorine.
741. Chlorides may also be formed by
How are chlo-
rides produced the action of hydrochloric acid on oxides.
from oxide*? Thug common salt or chloride of sodium
may be made by mixing hydrochloric acid and soda.
The hydrogen of the acid and the oxygen of the soda
unite to form water, while the chlorine of the acid and
the metal sodium unite, to form the chloride. This is
a case of double decomposition, resulting from double
elective affinity. The chloride commonly corresponds
to the oxide from which it is produced. Thus soda,
which is a protoxide, yields common salt, which is a
protochloride. Again, sesquioxide of iron, containing
three atoms of oxygen to one of metal, yields susqui-
chloride of iron containing the same proportion of chlo-
rine.
How are the ^2. The insoluble chlorides may be ob-
insolubie chlo- tained directly in a solid form by a similar
rides obtained „
directly in a, double decomposition. Thus, chloride of
solid form? sodium and oxide of silver in solution,
296 CHLORIDES.
yield, when mixed, a precipitate of chloride
of silver ; newly-formed oxide of sodium or
soda remains in solution. The latter unites
with the acid originally employed to dissolve
the oxide of silver. This is commonly nitric
acid.
743. CHLORIDE OF SODIUM. — COMMON
From what _. i • /• i •
sources is com- SALT. — Common salt is found in great
Obtained? abundance in Poland and other countries,
as Rock salt, which is regularly mined like
coal. It is also obtained by evaporating the water of
the sea or salt springs, in the sun or by artificial heat.
When the salt water is boiled down, the salt separates
in crystals, while the impurities remain in the small
portion of liquid which is not evaporated. These con-
sist principally of chloride of magnesium and other
salts. Contrary to the general rule, salt is equally solu-
ble in cold and hot water.
744. When salt is to be made from
How is salt , . . .
produced from water which contains it in very small pro-
portion, it is a frequent practice in Europe,
to pump the weak brine to the top of large
heaps of brush, and allow it to trickle through them.
The object of the method is to produce a large evapo-
rating surface. The air, as it passes through the heaps,
carries away a large part of the water, and leaves the
salt behind. The strong brine which is collected below,
is then boiled down, as before described. The annual
produce of the salt spring at Syracuse, New York, ex-
ceeds 5,000,000 bushels.
CHLORINE. 297
745. Beautiful crystals of common salt
How may crys- . . .. ' , ..
tals of salt be may be obtained by gradually evaporating
obtained? a saturale(j solution. This will be accom-
plished by keeping it for some time moderately warm,
on a stove or in the sun. The crys-
tals are shaped as represented in the
figure, and are made of innumerable
smaller cubes, which build them-
selves regularly upon the edges as the larger crystals
sinks little by little into the solution.
746. USES OF COMMON SALT. — The use
How does salt
act to preserve of common salt in preserving the flesh of
flesh? animals from decay, depends in part on
the fact that it extracts from the flesh a large propor-
tion of water. It thus, to a certain extent, dries them.
This action will be immediately observed if a little
salt be sprinkled upon flesh. It will speedily draw
out the juices of the meat, and itself disappear, by dis-
solving in them.
ffowmucksait 747' SEA WATER.— Every pound of sea
is contained in water contains from one-half to five-
sea water ? in
the water of eighths of an ounce of salt. The greater
theDeadSea? part of thig is chloride of sodium or com-
mon salt. The water of the Dead Sea contains a
much larger proportion, and is more than an eighth
part heavier than pure water. Owing to its greater
density, a muscular man floats breast high in it without
the least exertion. Fresh eggs, which sink in sea
water, float in that of the Dead Sea, with one-third of
their length above the surface.
13*
298 CHLORIDES.
748. CHLORIDE OF LIME. — BLEACHING
On what does
the value of POWDER. — The commercial article of this
? name is PrePared bY passing chlorine gas
over lirne. It is a white powder, with an
odor similar to that of .chlorine gas. Its value depends
on the fact that the gas is thus brought into a solid
form, and made capable of transportation. It may be
released again by the simplest means, to be used as a
bleaching and disaffecting agent. The addition of an
acid, as has been seen in the chapter on chlorine, is all
that is necessary to effect this object. It occurs, in-
deed, spontaneously in the moistened powder, through
the action of the carbonic acid of the air.
749. ILLUSTRATION. — To illustrate its
How may its
properties be bleaching power, a strip of calico may be
illustrated? soaked in a solution of the chloride, and
then in acid water. Nascent chlorine is thus liberated in
the fibre of the cloth, and is more effectual than if
otherwise applied.
750. FORM OF COMBINATION. — The che-
How are its ... i • -,
elements com- mical action which occurs in the formation
lined? of chloride of lime is as follows. The
chlorine combines with both constituents of the lime
forming with its metal chloride of calcium, and with its
oxygen, hypochlorous acid. This acid combines as it
is produced, with another portion of lime, forming a salt.
Bleaching powder is therefore a mixture of chloride of
calcium and hypochlorite of lime, with a certain pro-
portion of lime still uncombined. The name chloride
of lime has no chemical propriety. The mixture is,
practically, chlorine and lime, for as soon as an acid is
CHLORIDE OF ALUMINIUM. 299
added, all of the original lime is re-formed and chlorine
is evolved.
751. CHLORIDE OF ALUMINIUM. — This
How is chlo-
ride of alumi- salt is of peculiar interest and importance,
"pared*? *' *n v*ew °^ *ts employment in the prepara-
tion of the new metal aluminium. It is
prepared by heating alumina at the same time with car-
bon and chlorine. The alumina is torn asunder, as it
were, by the affinities which are thus brought into play.
The carbon takes its oxygen and passes off with it as car-
bonic oxide, while the chlorine takes the metal and es-
capes with it as volatile chloride of aluminium. The
carbon in the process is supplied by coal tar. The
process is conducted in iron retorts, the materials hav-
ing been previously ignited together before their intro-
duction.
How is it pu- 75%- The chloride is impure, from the
rifted? presence of volatile sesquichloride of iron.
This is separated by leading the uncondensed vapors
over highly heated points of iron. The iron has the
effect of removing part of the chlorine from the ses-
quichloride of iron and reducing it to a non-volatile
protochloride. It is thus stopped in its course, while
the chloride of aluminium passes on unaffected. It con-
denses in the cooler part of the apparatus, in the
form of colorless transparent crystals.
753. COLORED FLAMES. — A series of
What is said .
of colored beautiful name experiments may be made
flames?
assumes different colors according to the chloride em-
ployed. Chloride of sodium or common salt, gives
300 SALTS.
a yellow ; chloride of potassium, violet ;
chloride of calcium, orange ; chloride of
barium, yellow ; chloride of copper, blue.
Instead of the chlorides, other soluble
salts may be employed with the addition of a little hy-
drochloric acid. £, beautiful green may be obtained
from a copper coin moistened with strong nitric acid,
with the use of alcohol as before. The colors of fire-
works are similarly produced by the addition of the
above and certain other salts.
754. OTHER CHLORIDES. — The other
What is said i i • j /•
of other ckio- chlorides are not of sufficient general in-
terest to be here particularly described. Cor-
rosive sublimate, the uses of which are mentioned in
the chapter on Mercury, is a chloride of this metal.
Calomel is a subchloride of the same metal.
IODIDES, BROMIDES AND FLUORIDES.
755. The iodides and bromides are
What is said
of the iodides classes of salts analogous to the chlorides.
andbromides? Those of potassium, used in medicine and
in photography, are the most important.
756. DETECTION OF T<roioo<r IODINE. —
JTowistheblue -r' i 1.1 • i -, -, -,-
iodide of A beautiful blue is prepared by adding a
pared r6' little cnlorme water and starch paste to a
solution of iodide of potassium. The
chloride sets iodine at liberty, which then combines
with starch to form the blue compound. By this test
iodine can be detected in a liquid which contains but a
IODIDES AND BROMIDES. 301
millionth part of this element. By the substitution of
bromide of potassium in the experiment, an orange
color is produced.
How is this 757. TEST FOR CHLORINE AND IODINE. —
experiment rp^e experiment may also be made by
employed as a . ' .
test for chlo- moistening a slip of paper with starch and
iodide of potassium, and holding it in an
atmosphere containing a little chlorine gas.
An extremely small quantity of chlorine is
thus indicated, and the prepared paper thus
becomes a test for chlorine. Such paper is
also used to show the presence of ozone in
the air.
758. CHANGE OF COLOR BY HEAT. — By
What is said . . . '
of the iodide of mixing solutions of iodides of potassium
and corrosive sublimate or chloride of mer-
cury, a beautiful scarlet iodide of mercury is produced.
On heating the dried precipitate it becomes yellow.
The experiment is best made with two watch glasses.
The iodide is heated in the lower one and collects by
sublimation, with changed color, in the upper.
What effect is 759. CHANGE OF COLOR BY TOUCH.
produced by On touching the yellow incrustation with
touching the . . ,. ,, , . ,
yellow incrus- the point of a needle, it is immediately
tation? stained scarlet at the point of contact. The
color gradually spreads, as if it were a contagious dis-
ease, through the whole mass, until every particle has
regained its original scarlet. This experiment fur-
nishes a very remarkable instance of change of an im-
portant property without change of composition. As
302
SALTS.
the change of color proceeds, the small scales of which
the yellow iodide is composed break up into octa-
hedrons. The change of color is regarded as a conse-
quence of the re-arrangement of atoms, which produces
the change of form.
FLUORIDES.
What is said 760. FLUOR-SPAR. — The fluorides, with
of 'fluor-spar ? fae exception of those of the alkalies, are
for the most part, white insoluble compounds. The
only one of especial interest, is the beautiful mineral
knoivn as fluor-spar. This mineral is a fluoride of
calcium. It is found of white, green, purple
and rose color, crystallized in regular cubes
or octahedrons. Hydrofluoric acid, which has
the remarkable property of etching glass, as
before described, is prepared from it.
SULPHURETS.
Define a sul- ?^- The compounds of the metals with
phuret. sulphur are called sulphides or sulphur ets.
They are of various colors, and, for the
most part, insoluble. Iron pyrites, and ga-
lena or sulphuret of lead, are examples.
The figure represents a crystal of magnetic pyrites,
which is one of the sulphurets of iron. The form be-
longs to the sixth or hexagonal system.
762. PREPARATION. — Most of the sul-
How are sul-
phurets gene- phurets may be produced by adding hydro-
paaredT~ sulphuric acid to solutions of the different
metals or their salts. Sulphur and metal
SULPHURETS. 303
unite and precipitate, while the hydrogen and oxygen,
previously combined with them, form water.
Mention the 763. The sulphuret of zinc is white ;
colors of some tnat of arsenic yellow ; and that of anti-
of the sulphu- ' J
rets. mony, orange. The remainder of the in-
soluble sulphurets are black. Solutions of
white vitriol, arsenious acid, and tartar emetic
may be used, as above directed, to produce sul-
phurets of zinc, arsenic and antimony. If
the zinc precipitate should be colored, it is
owing to the presence of iron in the salt, as
impurity. Blue vitriol may be employed to produce
black sulphuret of copper.
764. The sulphurets of ammonium, po-
What is said
of the sulphu- tassmm and sodium, cannot be precipitated
raika/ielh?e by this Process- Being soluble, they re-
main in the liquid. Solutions of the caus-
tic alkalies are to be used in preparing them. The so-
lutions of these sulphurets are useful, as they may, in
many cases, be substituted with advantage for hydro-
sulphuric acid, in precipitating sulphurets from solutions
of other metals. Certain other sulphurets are soluble,
and do not precipitate, as will be seen from the table
in the Appendix.
765. LIVER OF SULPHUR. — There are a
What is liver f . f
of sulphur? number of sulphurets of potassium, con-
jj u pre" taining each a different proportion of sul-
phur. That which contains five atoms of
sulphur, to one of metal, is called, from its peculiar
color, liver of sulphur. It is prepared by boiling flowers
of sulphur in a strong solution of potash. It may also
304 SALTS.
be made by fusion of the same materials. The proto-
sulphuret can be made from the sulphate, by reduction
with hot carbon. Certain other soluble sulphurets may
be prepared in the same manner.
766. MILK OF SULPHUR. — This form of
How is milk of , . . .
sulphur pre- sulphur, like that just mentioned, is used
pared? ^ me(jicine. It may be prepared from a
solution of the liver of sulphur, by the addition of an
acid. The latter combining with the potassa, the sul-
phur is precipitated in a state of the finest division,
giving to the liquid the appearance of milk.
767. OTHER SULPHURETS. — The natu-
of the other ral sulphurets have colors different from
sulphurets? ^Q similar compounds when produced, as
above, by precipitation. Thus, the natural sulphuret
of lead, or galena, has the color of the metal ; that of
mercury is red, and is called cinnabar ; that of zinc,
called zinc blende, and by miners, black jack, is of dif-
ferent shades — brown, yellow and black. The precipi-
tated sulphuret of mercury turns red by sublimation,
and in this state forms the familiar pigment called ver-
milion. Sulphuret of iron, which is employed in
making hydrosulphuric acid, may be prepared by hold-
ing a roll of sulphur against a rod of iron previously
heated to whiteness. This may be readily done in any
blacksmith's shop. The fused sulphuret falls in glo-
bules from the surface of the iron.
SULPHATES. 305
SULPHATES.
768. The sulphates, with the ex-
What is said
of the color ception of those of the alkaline
are f°r the mOSt
ble salts, of colors corresponding to
the solutions of the corresponding metals. The
figure represents a crystal of gypsum. The form
longs to the fourth system.
769. PREPARATION. — The sulphates are
How are the .,,,., , , ,.
sulphates produced either by the direct combination
of sulphuric acid with the proper oxide, or
by its action on the metals. The latter has been already
particularly described in the section on sulphuric acid.
They are also sometimes formed in nature, by the
action of the air on sulphurets. In this action, the
metal is converted into oxide, and the sulphur into acid,
which together form the sulphate. Green vitriol is
sometimes thus formed in soils, from sulphuret of iron
ox fool's gold.
What ix gyp- ?70. SULPHATE OF LIME. - GYPSUM. -
sum? This is a white, soft mineral, occurring
abundantly in nature. The finer kinds are known as
alabaster. Finely ground, it is employed extensively
as a fertilizer of the soil under the name of plaster.
Plaster of Paris is produced by heating gypsum until
its water is expelled. The plaster, when pulverized,
has the property of setting with water, or, in other
words, forming a hard coherent mass.
771. PLASTER CASTS. — These are pro-
How are plas- .
ter casts pro- duced by reducing the burned or powdered
duced? gypsum to the consistence of cream, with
306 SALTS.
water, and then pouring it into moulds. A coin may
be copied by pouring such a paste into a small paper box
containing the coin. Two parts of ordinary ground
gypsum, heated moderately until vapor ceases to escape,
and then mixed with one part of water, form a good
proportion. The heat should not be carried very far
beyond that of boiling water, or the plaster refuses to
set.
772. The hardening of the plaster part
ter casts hard- takes place very rapidly. It is owing to
the re-combination of the material with
water. The water thus absorbed exists in a solid form
in the compound, as in other salts.
773. ALUMINATED PLASTER. — Harder and
What is alu-
minatedplas- better casts, more nearly resembling mar-
ble, are made by steeping the burned gyp-
sum for six hours in strong alum water, and then re-
heating it at a higher temperature. After being again
pulverized, it may be used like ordinary plaster, but
requires more time to harden.
774. SULPHATE OF SODA. — GLAUBER'S
Describe sul- .-.,, . , . •> r
pkateof soda, SALT. — This is a white salt, forming crys-
and itsprcpa- ta}s belonging to the third system, such as
ration. J
are represented in the fig-
ure. It is used to some extent in medi-
cine, and in large quantities for the pro-
duction of carbonate of soda. It is prepared by pour-
ing oil of vitriol upon common salt. A double decom-
position takes place between the salt and the water of
the acid ; hydrochloric acid is formed, which passes off,
and soda, which remains combined with the sulphuric
SULPHATES. 307
acid. It is to be understood that this reaction between
water and common salt, takes place only when sulphuric
acid is present. The method of making the experi-
ment is given in the paragraph on the preparation of
hydrochloric acid.
What is said 115. Sulphate of soda may be obtained
of its crystals? m crystals, by evaporation. These crys-
tals, like those of many other salts, lose their combined
water, on exposure to the air, and become converted
into a white powder. This change is called efflores-
cence, and the salt which experiences it is called efflo-
rescent. In preparing the salt on a large scale, for
conversion into carbonate of soda, large quantities of
hydrochloric or muriatic acid are incidentally pro-
duced.
Whatissul- 77^' SULPHATE OF BARYTA. — The sul-
pkate of ba- phate of baryta is a white insoluble sub-
ryta? How . /
prepared? stance, which may be obtained, as a pre-
cipitate, by double decomposition of any
soluble baryta salt with a soluble sulphate. It is a
mineral of frequent occurrence, known as heavy spar.
It is used for the adulteration of white lead, in which
it may be easily detected as a residue, on dissolving
the white lead in dilute nitric acid. The sulphate of
lead is another of the few insoluble sulphates.
777. ALUM. — Ordinary alum is a double
Describe \
alum, and its sulphate of alumina and potassa. Solu-
prcparation. ^^ of the tWQ ^^ when mixed? CQm_
bine to form the double salt. The sulphate of alu-
mina required in the process may be obtained by dis-
solving alumina from common clay by sulphuric acid.
308 SALTS.
Or it may be produced by exposing cer-
tain clays or slates, which contain sul-
phuret of iron to the action of the air.
Under these circumstances, the sulphur
becomes converted into sulphuric acid,
which unites with both oxide of iron and alumina.
From this mixture the protosulphate of iron is sepa-
rated by crystallization, leaving a solution of sulphate
of alumina to be used in the preparation of alum.
What is burnt ^8. On heating alum in a crucible or
alum ? pipe-bowl, it swells up into a light porous
mass, and is converted into burnt alum. At
the same time it loses its water of crystalliza-
tion, of which it contains twenty-four molecules
to each molecule of the double sulphate.
779. OTHER ALUMS. — The name, alum,
What is said
of other is appplied to a number of salts of analo-
gous composition to the common alum al-
ready described. In one of these, sesquioxide of chro-
mium, and in another, sesquioxide of iron, takes the
place of the alumina or sesquioxide of alumina. In
a third kind of alum, oxide of ammonium replaces the
potassa. All of these alums contain the same number
of molecules of water of crystallization. They have
all the same crystalline form, and. if mixed in solu-
tion will crystallize together. They are, therefore,
isomorphous salts. Their perfect analogy of composi-
tion will be best seen by the inspection of their formu'
Ise, given in the Appendix.
What is said 780. OTHER SULPHATES. VlTRIOLS.
of vitriols? Several of the sulphates have received the
NITRATES. 309
common name of vitriols. Sulphates of zinc, copper,
and iron are called respectively white, blue, and green
vitriol. Green vitriol readily absorbs oxygen from the
air, and becomes brown, from the accumula-
tion of peroxide of iron upon its surface. A
solution of it is changed to a yellowish-red
color, by the oxidizing action of either nitric
acid or chlorine. A crystal of blue vitriol is
represented in the figure. The form belongs to the
fifth system.
NITRATES.
How are ni- 781. The nitrates are formed by
transformed? fa^ action of nitric acid on metals,
as already explained, and also by the action of
the acid on oxides previously formed. In the
latter case, the metallic oxide takes the place of
the water of hydration, which always belongs
to the acid. They are also produced by double
decomposition. The figure represents a crystal of salt-
petre. The form belongs to third system. This latter
method is illustrated below, in the preparation of nitrate
of potassa from the nitrate of lime.
782. NITRATE OF LIME. — This salt is
How is nitrate .
of lime, pro- of considerable interest, from the fact that
it is employed in the production of salt-
petre or nitre. It is formed in the so called, nitre beds,
by mixing together refuse animal matter with earth and
lime. In the gradual putrefaction of the animal mat-
ter which follows, its nitrogen takes oxygen from the
310 SALTS.
air, and is converted into nitric acid. The acid then
combines with the lime to form the nitrate. The salt
is afterward extracted by water. The formation of
nitric acid, above mentioned, takes place only in the pre-
sence of alkaline substances. In their absence the ni-
trogen passes off, combined with hydrogen, as am-
monia. Even in the presence of lime, there is reason
to believe that ammonia is first formed, and its consti-
tuents afterwards converted into nitric acid and water.
783. NITRATE OF POTASSA. — NITRE, OR
Explain the
formation of SALTPETRE. — This salt is a constituent of
certain soils, especially in warm climates.
These soils always contain lime, and are said to be
never entirely destitute of vegetable or animal matter.
It is obvious, therefore, that nitrate of potassa may be
formed in them, as the same salt of lime is formed in
the nitre beds just described. A small proportion of
nitric acid exists in the atmosphere, combined with am-
monia. This, also, may be a source of part of the
nitric acid of the nitrous soils. Again, it is probable
that nitric acid is slowly formed from the atmosphere
by the direct combination of its elements in the porous
soil. Nitre, on being highly heated, yields a third of
its oxygen in the form of gas.
784. Nitre is obtained from nitrous soils
Hew ^s nitre
obtained from, by lixiviation with water, and subsequent
nitron soils? crystallizatioiL From nitrate of Iim6j
it is produced by double decomposition with carbonate
of potassa. Carbonate of lime precipitates, while nitrate
of lime remains in solution. This may be afterward
poured off, evaporated, and crystallized.
NITRATES. 311
785. USES OF NITRE. — Nitre is exten-
Mention some
of the uses sively employed by the chemist and in the
arts, as an oxidizing agent. A few grains
of it introduced into a solution of green vitriol, or sul-
phate of iron, to which some free sulphuric acid has
been added, will immediately change its color. The
sulphuric acid sets nitric acid at liberty, to which the
oxidation and change of color are to be attributed.
Nitre, when heated, yields part of its oxygen, as before
stated. If heated with metals, it converts them into
oxides. The principal use of nitre, is in the manufac-
ture of gun-powder.
Howareni- - NlTRATE OF AMMONIA. - LAUGHING
trate of am- GAS. — Nitrate of ammonia may be prepared
monia and ,,
laughing gas irom the carbonate, by evaporation with
produced? nitric acid When heatedj the hydrogen
of the ammonia, and an equivalent quantity of the ox-
ygen of the nitric acid, unite to form water, and the
residue of both passes off as protoxide of nitrogen, or
nitrous oxide. The compound is also called laughing
gas, from the exhilarating effects which it occasions,
when breathed in considerable quantity. Impurity
of material or excess of heat occasion the production
of an impure and deleterious gas. In view of these
facts, the preparation, and inhalation of laughing gas
is not to be recommended to the student.
Ex lain the ^^ ' GUN-POWDER. — Gun-powder is a
action of the mixture of nitre, charcoal, and sulphur.
°o/ When ignited, the carbon burns instanta-
neOusly, by help of the oxygen of the nitre,
thus producing a large volume of carbonic acid gas. To
312 SALTS.
this gas, together with the nitrogen which is also set at
liberty at the same moment, the force of the explosion
is due. The sulphur, at the same time, combines with
the potassium of the nitre, and remains with it as a
sulphuret of potassium. Three equivalents of carbon
to one of nitre, and one of sulphur, expresses very
nearly the composition of gun-powder. It varies, how-
ever, according to the uses for which it is intended,
and the country in which it is manufactured. From
the proportion, by equivalents, the relative weight of
the constituents can readily be calculated.
788. COLLECTION OF THE GASES. — For
How arc the . -in- /•
gases col- the production and collection of the gases
evolved in the combustion of gun-powder,
the fuses of ordinary "firecrack-
ers" may be employed. Several
of them are to be ignited at the
same time, in an ordinary test-
tube. The mouth of the latter
being then brought under a filled
and inverted vial, the gases are
collected as fast as they are evolved.
789. NITRATE OF SILVER. — Nitrate of
Describe ni- ., . i j •
trate of silver, silver, or Lunar caustic, is employed, in
What are its surgerVj for cauterizing wounds. A solu-
tion of the salt in which the oxide has
been precipitated by ammonia, and re-dissolved by a
slight excess, is extensively employed as an indelible
ink. The black color comes from oxide of silver, and
finely divided metal, precipitated in the cloth. It
may be removed by soaking in solution of common
CARBONATES. 313
salt, and thus converting the silver of the mark into
chloride of silver. This is soluble in ammonia, and
may be afterward extracted by that agent. Nitrate
of silver is also the basis of most dyes for the hair.
Describe the 790. OTHER NITRATES. — Nitrate of soda
other nitrates. js a wnite salt, found native in South
America. It is used in the manufacture of nitric acid,
and, to some extent, as a fertilizer of the soil. The
remaining nitrates are soluble salts, of colors corres-
ponding to the solutions of the metals, as already de-
scribed. The uses of the nitrates of silver and bismuth
have already been mentioned.
CARBONATES.
Describe the 791. CARBONATES. — The carbonates are,
carbonates. for tne most part) wnite or light colored
salts, of which chalk may serve as an example. The
carbonate of copper is found native, both as blue and
green malachite. All of the carbonates,
excepting those of the alkalies, may be
decomposed by heat. The latter are sol-
uble, and retain their acid at the highest temperatures.
The figure represents a crystal of carbonate of lime or
calc spar.
792. PREPARATION. — The insoluble car-
How are the ...
insoluble car- boiiates may be produced by precipitating
solutions of the metals or their salts, by
carbonic acid or solutions of the alkaline
carbonates. In the latter case, a double decomposition
occurs, with exchange of acids and bases.
14*
314
SALTS.
What is said
of carbonate
of potassa ?
Describe car-
bonate of
soda.
793. CARBONATE OF POTASSA. — POTASH.
The method of preparing potash and
pearlash, from wood ashes, has already
been considered in the paragraph on Potassa. Saleratus
is a carbonate containing a large proportion of carbonic
acid. Its use, for u raising" bread and cake, is familiar.
The acid employed with it, sets the carbonic acid gas
at liberty and thus puffs up the " sponge."
794. CARBONATE or SODA. — SODA. —
Carbonate of soda is commonly known
under the name of soda. It is a white
soluble salt, familiar from its use in Seidlitz and soda
powders. Its carbonic acid is the source of the effer-
vescence in these preparations.
795. Carbonate of soda is prepared from
flow i.s carbo- . .
note of soda the sulphate of soda. 1 his salt being
prepared? heated with charcoal is converted into
sulphide of sodium. On heating the latter with car-
bonate of lime, a double de-
composition occurs, and car-
bonate of soda is produced,
with sulphide of calcium as
an incidental product. Both
parts of the process are com-
bined in practice. Sulphate
of soda, chalk, and coal, are heated together in a rever-
beratory furnace, the carbonate of soda is then dissolved
out from the fused mass, dried, purified, and subse-
quently crystallized. The sulphide of calcium would
dissolve at the same time, and thus defeat the process,
were it not rendered insoluble by combination with a
certain quantity of lime.
CARBONATES. 315
Describe an- 796. Another method of manufacturing
other method, carbonate of soda, consists, essentially,
in separating sulphur from the sulphate, by means of
oxide of iron, and substituting carbon in its place. In
this process also, the materials are heated with charcoal,
in a reverberatory furnace, and the carbonate afterward
extracted by water. The impure uncrystallized carbo-
nate of soda, is known in commerce, as soda ash, and
is largely employed in the manufacture of hard soap,
and in other processes.
What is sal 797. CARBONATE OF AMMONIA. SAL VOL-
volatile? ATILE. — The ordinary sal volatile of the
shops, used as smelling salts, is a carbonate containing
three equivalents of acid to two of base. It wastes away
gradually in the air, and passes off in a gaseous form.
798. PREPARATION. — Sal volatile is pre-
How is sal .
volatile pre- pared by heating together carbonate of
pared \ime and chloride of ammonium. Carbo-
nate of ammonia immediately passes off', while chloride
of calcium remains behind. The carbonate is led into
a cold pipe or chamber, where it takes the solid form.
The mixture of chalk and sal ammoniac is sometimes
used as smelling salts. The production of sal volatile
from the mixture is very gradual if heat is not applied.
799. The property from which
How is it
proved to be the salt receives its name, may
volatile f be illustratedj by holding in its
vicinity a rod or roll of paper, moistened with
strong muriatic acid. A dense cloud of sal
ammoniac is immediately produced in the
air, from the union of the two vapors. The
316
SALTS.
experiment is more striking, if the sal volatile is warmed
in a cup or other vessel. This salt is sometimes
used by bakers for making bread and cakes light and
spongy.
800. CARBONATE OF LIME. — Carbonate
of carbonate of lime, in the form of chalk, marble, arid
of ime? ordinary limestone, is a most abundant
mineral. Whole mountain chains consist of the latter
rock. The shells of shell-fish are principally carbon-
ate of lime. There is good reason, indeed, to believe
that all limestones have their origin in accumulations
of such shells, which have been consolidated in the
course of ages.
801. SOLUBILITY IN CARBONIC ACID.—
The solubility of carbonate of lime in
carbonic acid is readily shown, by passing
a current of the gas through
water clouded with pulver-
ized chalk or marble. Other mineral
substances which form the food of plants
are dissolved by the same means, and
then find their way into the roots, to 5
subserve the purposes of vegetable life.
802. INCRUSTATIONS IN BOILERS. — Car-
What is said
of incrusta- bonate of lime dissolved in carbonated
twns m boil- water js again precipitated on boiling the
solution. This is owing to the escape of
the acid. Incrustations in tea-kettles and steam-boilers,
in limestone districts, owe their origin to the same cause.
In some cases, the crust is formed of gypsum, or other
earthy matters contained in the water. One method
of avoiding this inconvenience in steam-boilers, is by
How is the
solubility of
carbonate of
lime in car-
bonic acid
shown ?
PHOSPHATES. 3l7
the addition of a smaller boiler, in which the water is
first heated, arid its sediment deposited.
Give the sta- 803. STALACTITES. — The masses of car-
lactites. bonate of lime which hang like mineral
icicles from the roofs of caverns are called stalactites.
The water that penetrates the soil is the architect of
these curious forms. Impregnated with carbonic acid,
derived from decaying vegetation, it takes up its load
of carbonate of lime as it settles through the rock, and
deposits it again on exposure to the air of the cavern,
in various and often fantastic shapes. Another portion
of water, dripping to the floor of trje cavern, builds up
similar forms, called stalagmites, from below.
804. ARTIFICIAL MARBLE. — The surface
How ts artifi-
rial marble of wood or stone may be marbled by cov-
produccd? ering it with successive coats milk of lime,
and allowing each in turn to dry before the next is ap-
plied. The surface is then smoothed and polished, and
carbonic acid finally applied, by which it is converted
into marble. The milk of lime is simply a mixture
of slaked lime and water, and may be so colored as to
produce a variegated surface.
PHOSPHATES
Describe the 805. PHOSPHATES. The phosphates,
phosphates. wjth the exception of those of the alka-
lies, are, for the most part, white insoluble salts.
Phosphate of lime may be taken as an ex-
ample. The white residue which is obtained
on heating the bones of animals, until all the
animal matter is destroyed and expelled, is principally
phosphate of lime.
318 SALTS.
806. Ordinary phosphoric acid has the
Why is ordi- ,, , . .
naryphospho- property of combining with and neutrah-
edtrTba ticT~ zing tnree e(luivalents °f Dasej instead of
one, as is the case with most other acids.
It is therefore called a tribasic acid. The hyd rated
acid contains, also, three equivalents of water, and may
be regarded as a salt in which the water acts the part
of base. Arsenic acid is similar in this respect, as well
as in the amount of oxygen which it contains, and in
the salts which it forms with bases. Two other kinds
of phosphoric acid may be prepared from that above
mentioned ; the first combines with one, and the second
with two equivalents of base.
807. PREPARATION. — The phosphates of
How are the . f J
phosphates the alkalies may be produced by the ac-
preparcd? tion of phosphoric acid on the proper car-
bonates. The remaining phosphates may be precipi-
tated by solution of phosphate of soda, from solutions
of the metals or their salts. As in other cases of pre-
cipitation, there is here a double decomposition, with
exchange of acids and bases.
808. SUPERPHOSPHATE OF LIME. — A
Describe the . •»•-»•
preparation mixture bearing this name, formed by the
action of dilute sulphuric acid on burned
bones, is extensively used as a fertilizer of
the soil. The sulphuric acid, when added, appropri-
ates part of the lime of the bones, forming with it
gypsum ; at the same time, it leaves the phosphoric
acid which it displaces, free to combine with another
portion of phosphate of lime and thereby to render it
soluble. The commercial article is a mixture of this
SILICATES. 319
soluble substance with the gypsum and animal char-
coal produced in its formation. Other materials are
often added, increasing or diminishing, according to
their nature, its agricultural value. The basis of the
manufacture, is commonly the refuse bone black of
the sugar refineries employed in the process.
809. OTHER PHOSPHATES. — The phos-
Whatis mid .
of other phos- phate of soda is used in medicine
phates? and j^ tne cnemistj to produce
other phosphates. The phosphate of silver is
a beautiful yellow precipitate, obtained by pre-
cipitating salts of silver with phosphate of
soda or any other salt containing phosphoric acid.
SILICATES
What is said 810. The silicates form an exceedingly
of silicates? iarge c|ass of salts. They are, for the
most part, insoluble, and are variously colored.
Mica and feldspar, two of the constituents
of granite, may serve as examples. As com-
ponents of this and other rocks, the silicates
make up a very considerable portion of the
mass of the earth.
811. PREPARATION. — Most silicates may
How are sili- . f _
catespre- be artificially formed by fusing together
pared? quartz sand, with the proper oxide. This
is done in the manufacture of glass, to be hereafter
described. Silicates may also be formed by precipita-
ting solutions of metals or their salts by the solution
of an alkaline silicate.
320 SALTS.
.812. CLAY. — Clay is a silicate of alu-
composition mina, commonly containing silicate of po-
tassa and other materials in small pro-
portion. The best kaolin or porcelain clay is perfectly
white, and is nearly pure silicate of alumina.
How is soluble 813. SOLUBLE GLASS.— Soluble glass is
glass made? made by fusing sand with potassa or soda.
Its production may be illustrated in a soda bead, by
subsequently re-fusing it, with addition of sand. As
the silicic acid combines with the soda, carbonic
acid is expelled, as will be evident from an efferves-
cence on the surface of the bead. Soluble glass is
sometimes used as a sort of varnish for rendering wood
fire proof.
814. WINDOW GLASS. — Common window
•manufacture glass is a silicate of lime and soda. To
°flaWssnd°W f°rm il> Chalk> S°da> quartz salld and °ld
glass are fused together until the mass be-
comes fluid. The molten glass is then blown, by
means of an iron tube, as soap bubbles are blown
with a pipe. The first form of the bubble is
that represented in the figure. The glass blower
next contrives to lengthen out the bubble, as he
blows it, to a larger size, and finally to blow out
the end by a strong blast from his lungs. It
is then trimmed with a pair of shears, and the
other end cracked off by winding round it a thread
of red hot glass. Such a thread is readily produced
by cfipping an iron rod into the pot of molten glass, and
then withdrawing it. The bubble of glass is thus
GLASS.
321
brought to the form of a cylinder, such as is
represented in the figure. The cylinder is
then cracked longitudinally, by letting a drop
of water run down its length, and following it
by a hot iron. It is subsequently reheated,
opened, and flattened out into a sheet, which
is then cut into paries of smaller size, if required.
How are glass 815. GLASS TUBES.— To make a glass
tubes made? tube, a bulb is first blown, such as is repre-
sented on the previous page. An assistant then at-
taches his tube to the hot bulb at the opposite side,
and moves backward. The glass is thus drawn out,
as if it were wax, and the cavity within it is elongated
to a smooth and perfect bore.
816. GLASS BOTTLES — Bottles and a
Glass bottles? . f .
great variety of other objects of glass, are
made by the enlargement of similar bulbs within a
mould of the required shape. Bottle glass is usually
made of cheaper and less pure materials than window
glass, and contains, in addition to the materials before
mentioned, alumina and oxides of iron and manganese.
It owes its green color to the protoxide of iron.
Glass mir- 817. GLASS MIRRORS. — Plate glass, such
rors? as is used for mirrors, instead of being
blown, is cast in metallic tables of the required shape,
and then rolled out and polished.
Wha.n*crys~ 818. CRYSTAL GLASS. — This name is
tal glass ? given to a highly brilliant glass, contain-
ing potassa and litharge as bases. It is used for prisms,
lenses, lustres, and the finer qualities of cut glass ware.
14*
SALTS.
With the addition of borax, it is also employed for im-
itations of precious stones.
What is ena- 819. ENAMEL. — Enamel is an opaque
md? glass, produced by the addition of some
material which does not dissolve in the fused mass.
Binoxide of tin is the material commonly employed.
Various tints may be imparted to enamel, as to ordi-
nary glass, by the addition of small quantities of me-
tallic oxides. A thin surface of enamel is often baked
on to a metallic surface, as in the case of watch dials,
and various objects of jewelry.
How is glass 820. COLORED GLASS. — Glass is colored
colored? an(j stained by the addition of various me-
tallic oxides. The peculiar coloring effects of these
substances have already been mentioned, in the sec-
tion on Oxides.
EARTHENWARE.
What is the 821. Clay is the basis of all earthenware,
basis of all from the finest porcelain to the coarsest
earthenware?
How is porce- brick. Being first fashioned by moulds or
lain made? ^_ means jnto the
proper form, it is dried, baked, and
subsequently glazed, to render it
impervious to water. In the man-
ufacture of porcelain, glazing is not
essential. Sand and chalk are ad-
ded to the original material, and
the heat is carried so high as to
bring the whole mass into a semi-
vitreous condition. This is also
the case in certain kinds of stone-
BORATES. 323
ware. Porcelain is, however, commonly glazed to add
to its beauty.
822. GLAZING. — Earthenware after its
Describe tlie
process of first baking is porous, and therefore unfit
glazing. ^ mogt useg ^or Wj1'cj1 ^ js intended. It
is subsequently covered with a thin paste formed of
the constituents of glass. Being then subjcted a
second time to the heat of the furnace, a thin glass
or glaze is formed upon the surface. The glazing
of certain wares is effected by exposure at a high
temperature to vapors of common salt. A double de-
composition ensues with the oxide of iron which the
ware contains, by which soda is formed. This imme-
diately fuses with the silica and other materials to form
the glaze. The chloride of iron which is formed at
the same time passes off as vapor. A paste of pounded
feldspar and quartz, to which borax is sometimes added,
is employed in glazing porcelain.
823. PORCELAIN PAINTING. — Metallic
of 'porcdTin oxides form the basis of the pigments used
painting? «n pajntmg upon porcelain. The color-
ing effect of the different pigments is mentioned in the
chapter on metallic oxides. The patterns on ordinary
.earthenware are first printed on paper, and then trans-
ferred, by pressure, to the unglazed ware. The paper
is afterwards removed by a wet sponge.
BORATES.
What is 824. BORAX. — Borax is the only impor-
lorax? tant salt among the compounds of boracic
324 SALTS.
acid. The salt contains two atoms of acid to
one of base, and is therefore a biborate. It is a
white soluble salt, which swells up when heat-
ed, in consequence of the escape of its water
of crystallization.
How is borax 825. PREPARATION. — Borax is found in
prepared? solution in the water of certain shallow
lakes in India. It remains as an incrustation in the
beds of these lakes when they dry up in summer. It
is also prepared by the action of a solution of boracic
acid on carbonate of soda.
What is said 826. BORAX GLASS. — The light spongy
of borax glass? mass which is produced on heating borax,
may be melted down by greater heat and converted into
borax glass. This glass has the property of dissolving
metallic oxides, and receiving from them peculiar colors,
as described in a former paragraph. The chemist often
determines the metal which a salt or oxide contains,
by the color which it thus imparts to glass. The
method of making the experiment has already been
given.
827. SOLDERING, WELDING, ETC. — Borax
Why is borax . . \ .
employed in is employed in soldering metals, to keep
soldering? ^ metallic surfaces clean. It does this
by dissolving the coating of oxide which forms upon
them, and forming with it a glass which is fluid at a
high temperature, and easily pushed aside by the
melted solder. Its use in welding iron depends on the
same property. Borax is employed, to some extent, in
medicine. It is also a constituent of the glass called
CHROMATES. 325
jewellers paste, which is used in producing imitations
of precious stones.
CHROMATES.
828. CHROME YELLOW. — To prepare this
How is chrome . ., . ,
yellow pre- pigment, a solution of the commercial
pared? bichromate of potassa is added to a solution
of sugar of lead. A double decomposition ensues ; the
result of which is the production of a beautiful
yellow precipitate, known as chrome yellow.
The precipitate is a chromate of lead. The
bichromate of potassa used in the experiment, is
made from the mineral chrome iron, which has
been mentioned in a previous chapter. The acid itself,
which is without practical applications, may be made
from the salt. It contains, like sulphuric acid, three
atoms of oxygen.
How is chrome ^^' CHROME ORANGE. — Chrome yellow
yellow con- may be converted into chrome orange, by
verted into . . , , .
chrome digestion with carbonate of potassa. Cloth
dyed yellow by dipping it alternately into
a solution of bichromate of potassa and sugar of lead, is
instantaneously changed to orange by immersion in
boiling milk of lime. This action of the lime, as well
as that of carbonate of potassa, depends upon its ab-
stracting a. certain portion of the chromic acid, leav-
ing thereby a chromate of lead of different composi-
tion and color.
326 SALTS.
830. CHROME GREEN. — On adding sul-
Dcscribe the . . °
preparation phuric acid and a few drops of alcohol to a
solution of bichromate of potassa, the solu-
tion is immediately changed from red to
green. The alcohol has taken oxygen from the chro-
mic acid, and converted it into oxide, which remains
in solution, as a soluble sulphate. Part of the sulphu-
ric acid has at the same time combined with the potassa,
to form sulphate of potassa. It is to the presence of
the sulphate of chromium in solution that the color of
the liquid is due. By adding an alkali to the solution,
a green precipitate of the hydrated oxide is produced.
This oxide forms a kind of " chrome green." App. 830.
MAKGANATES.
831. CHAMELEON MINERAL. — By fusion
What is cha- ... ,
meleon miner- with nitre, the black oxide of manganese
may be still further oxidized, and converted
into an acid. The new acid at the same time com-
bines with the potassa of the nitre to form manga nate
of potassa. This salt has been called chameleon min-
eral, from the spontaneous change of color which
takes place in its solutions.
832. PREPARATION. — The experiment
How is chame-
leon mineral may be made by filling a pipe stem with
prepare . a mjxture of tne materials, and thrusting it
into burning coals. It may be made on a still smaller
scale before the blow-pipe, using a broken pipe-bowl to
support the materials. The compound dissolves in
water, forming a green solution, which on standing
is gradually changed to a beautiful red.
THE DAGUERREOTYPE. 327
833. EXPLANATION. — The addition of a
Explain the
action of sul- few drops of sulphuric acid, produces the
above-mentioned change instantaneously.
This acid combines with the potassa,
setting the manganic acid at liberty. One portion of
manganic acid then appropriates part of the oxygen of
the other part, and converts itself into hypermanganic
acid, which still remains combined with potassa, im-
parting the red color to the solution. The deoxydized
portion of the acid precipitates, at the same time, as bin-
per oxide. The remaining manganates are not of especial
interest or importance.
THE DAGUERREOTYPE.
834. THE DAGUERREOTYPE. — The da-
Explain the
guerreotype may be regarded as a painting
in mercury, upon a silver surface. The
employment of mercury is preceded by what may be
called an invisible painting upon the silver. This is ac-
complished, like the production of an image in a mirror,
by mere presentation of the picture, or other object
to be copied, before the prepared plate. The mercury,
afterward used in the form of vapor, adheres to the
plate, and forms its white amalgam, just in proportion
to the lights and shades of the previous image thrown
upon the plate.
Describe the 835. THE DAGUERREOTYPE PROCESS.— -
process of ta- jn or(jer to prepare the plate for what has
King daguer-
reotypes. above been called the invisible painting, it
is exposed to vapors of iodine, and thereby covered
328 SALTS.
with a coating of iodide of silver.* A picture or face
to be copied being presented before the prepared plate,
the light which proceeds from it acts chemically
upon the iodide of silver. It decomposes it, to a
certain extent, and separates the iodine, thus open-
ing the way for the mercurial vapor, which is afterward
to be employed. The light has this effect, just in pro-
portion to its intensity. That which proceeds from the
lighter portions of the face, or dress, has most effect ;
that from the black portions, none at all, and that from
the intermediate shades, an effect in exact proportion
to their brightness. When the plate is afterward ex-
posed to the action of the mercurial vapors, they find
their way to the silver surface and paint it white, just
in proportion as this chemical effect upon the iodine
has been produced, and the way has been opened for
their admission. The darker portions of the plate are
pure silver. They appear dark in contrast with the
white amalgam.!
836. USE OF THE LENS. — In taking da-
What is the
object of the guerreotypes, a lens is placed between the
object to be copied and the plate, in order
that the light which proceeds from the former may be
concentrated, and its effect thus increased.
* Bromide and chloride of iodine, are employed to give additional
sensitiveness to the plate. The iodide is thus made to contain a por-
tion of bromide and chloride of silver.
f The art of taking portraits from the life by the Daguerreotpe pro-
cess, was invented by Dr. J. W. Draper, of the University of New
York.
PHOTOGRAPHS. 329
837. CHEMICAL ACTION OF LIGHT. — The
What is said . . . .
of theckemi- chemical action or light, on which the
t production of daguerreotypes depends, is
rays possess one of tne mOst interesting and remarkable
this power ?
of chemical phenomena. The rays of
the sun are so subtle, that they pass through solid crys-
tal and leave no trace of their passage. Yet with them
comes a power that can overcome the strongest chemical
affinities, and resolve the compounds which it has pro-
duced into their original elements. This power resides
in what are called the chemical, act wic, or tit/ionic rays.
These are mingled, under ordinary circumstances, with
those of light, but are capable of separation by certain
media.
What are pho- $38. PHOTOGRAPHS. - Pictures produced
tographs ? through the agency of light, whether upon
silver, or paper, are, properly, photographs, or light pic-
tares ; the name, however, is especially appropriated
to the latter. For the purpose of illustration, a method
of producing negative pictures, as they are called, will
be here given.
H™ is scnsi- 839- The sensitive paper required in
tive paper the process, is prepared by floating a slip of
letter-paper, for two or three minutes, upon
salt water ; and then for double the time, with the same
side down, on a solution of nitrate of silver. Chlo-
ride of silver forms within the fibres, and renders the
paper sensitive to light. After each immersion, the slip
should be dried off by blotting paper. When finished, it
should be immediately laid away between the leaves
of a book, for protection against the light.
330 SALTS.
840. Such paper, if placed in direct
What effect
has direct sun- sun light, becomes violet, and then dark
ls?n*itive°pa- brown, in the course of a few minutes.
per? The change is owing to the partial decom-
position of the chloride of silver. A new substance,
of darker color, is then produced ; whether a lower
chloride of different shade, or a mixture of metal and
chloride, or a compound of oxide and chloride, is not
very certainly known.
841. If a cross or other device cut
How may cop-
be pro- irom dark paper, be pressed down upon
of sen- sensitive paper, by means of a glass plate,
sitive paper ? and be left to cover it during the exposure
to light, the paper will be pro-
tected beneath it, and an exact
copy of the device thus ob-
tained. The most delicate lace
may be copied hy the same method. In reproducing
engravings by this means, they must be previously
rendered translucent, so that the imprinted portions will
allow the light to pass. This may he accomplished by
waxing them, with the help of a hot iron, or by simple
oiling. The dark parts of the engraving appear light,
and the light portions dark, in the picture. By copying
the copy, a true representation of the original device,
called a " positive picture," is obtained. Both the " pos-
itive" and " negative" are soon destroyed by the action
of light upon the whole sensitive surface. But the
means exist for rendering them entirely permanent in
any exposure.
H X Y
COUNTERFEITING. 331
842. THE SILVER SOLUTIONS. — To prepare
How is the sil-
ver solution the silver solution, above required, put a
prepai three cent piece into a test-tube, having a
diameter a little larger than the coin itself. Then fill the
tube to the depth of an inch, with a mixture of equal
parts of nitric acid and water. The solution of the coin
commences immediately. When it is completed, fill
up the tube with water, mix well by shaking, and the
solution is ready for use. For the same quantity of
salt solution, enough common salt to fill about two-
thirds of an inch of the tube, may be used.
843. ANASTATIC PRINTING. — This name
Describe
briefly the is given to a process by which any kind
astatic print- °^ Panted matter, may itself be converted
illO ? into a plate, from which new copies may be
printed. It consists, essentially, in the transfer of the
letters, or other design, to zinc, by pressure, the paper
having been previously moistened by dilute acid.
The oil of the ink remains, and the paper is re-
moved. The zinc plate is then used, like an ordi-
nary lithographic stone. When the inked roller is
passed over it, the ink only adheres to the design, from
which an impression may then be taken by the ordi-
nary process.
What is said of 844 COUNTERFEITING. — Bank notes may
counterfeiting fa counterfeited by either of the above
by the above
process? processes. Great apprehension has been
felt, test they should render the use of paper money en-
tirely insecure. An effectual means of protection
against such counterfeiting, has recently been devised.*
* Serop van's patent.
332 SALTS.
Copying by the anastatic process, obviously depends
upon the absence of oil from the back ground of the
picture. The employment of an oil tint, instead of
blank paper, for the back ground, is therefore a perfect
security against it. Counterfeiting by the photographic
process depends on the fact, that the light which falls
on a picture is intercepted by the dark letters. If they
are printed in a transparent blue, the chemical rays
are permitted to pass through the printed as well as the
imprinted portions. A copy with the contrasts of the
original picture is thereby rendered impossible. By
printing with blue ink, on a back ground of some other
color, both of the securities against counterfeiting
above mentioned, are combined.
CHEMICAL ANALYSIS.
845. DIRECT METHOD. — In the process
Describe anal-
ysis by sol- of analysis, advantage is taken of the dis-
tinguishing properties of different sub-
stances, to effect their detection and separation. They
may sometimes be separated by the employment of a
solvent which acts upon one, and leaves the other mi-
dissolved. The separation of silver from gold in the
process of assaying, is a case in point.
Describe di- 846. A more common method is to bring
rect analysis tne wnole substance into solution, and
oy precipita-
tion, afterward separately to precipitate its sev-
eral constituents, by agents which have no effect upon
the rest. The separation of alumina from lime may
serve as an example. A mixture of the two being dis-
CHEMICAL ANALYSIS. 333
solved in acid, the former may be precipitated by am-
monia. The latter remains in solution and may be
afterward removed by some other agent.
847. INDIRECT METHODS. — Indirect me-
II lust rate the , , -
indirect mcth- thods of analysis are much more frequently
od- employed than either of the above. The
detection of silver in a copper alloy may serve as an
example. The alloy being first dissolved, hydrochloric
acid is added to the solution, as a test. The appearance
of a white insoluble curd, is taken as conclusive evi-
dence of the presence of silver. No other metal of an
alloy ever combines with the chlorine of hydrochloric
acid to form such a precipitate. The evidence is quite
as satisfactory to the chemist as that which would be
obtained by the separation of the silver in the metallic
form.
848. Neither is separation necessary, in
How is the .
weight calcu- order to ascertain the exact weight of the
lated? metal which has been precipitated. Ad-
vantage is here taken of the well-established law of
combination by definite proportions. The chloride of
silver produced in the experiment, is invariably of the
same proportional composition. It is made up of an
atom of silver, to every atom of chlorine. Its weight
being ascertained by the balance, the amount of silver
which it contains may be calculated with absolute pre-
cision, by help of the table of atomic weights. This
weight being compared with that of the original alloy,
gives, by a simple calculation, the per centage propor-
tion of silver which the alloy contains. The nature and
quantity of other constituents, whether of compounds
334 CHEMICAL ANALYSIS.
r
or mixtures, is determined by processes analogous to
these which have above been described.
849. SEPARATION INTO GROUPS. — In the
Nation into1 analysis of substances containing many con-
groups effect- stituents, a separation into groups, precedes
the isolation of the individual constituents.
This is effected by the use of certain agents, in suc-
cession, which have the property of precipitating whole
groups. These being again dissolved, are commonly
subdivided into smaller groups by similar means. The
detection and separation of the individual constituents
is finally accomplished by means already described.
Some general idea of the process of inorganic analysis
may be obtained from the foregoing. Particulars upon
this subject must be sought in works on analytical
chemistry.
335
TV.
ORGANIC CHEMISTRY.
CHAPTER I.
GENERAL VIEWS.
850. DEFINITION. — Organic chemistry is
Of what does . . .
organic chem- that division of the science which treats
istry treat ? Qf substances of animal or vegetable ori-
gin. Starch, wood, gums, and resins ; the juices, colo-
ring matters, and fragrant principles of plants; the
blood and flesh of animals ; all come under its conside-
ration. The process of germination, in which the
plant first comes to be a living thing ; the processes of
decay and putrefaction, in which it returns again to the
earth and atmosphere, are also to be treated under this
division of the subject. Most organic forms of matter
experience peculiar changes, and are converted into
new substances by chemical means. The products of
such transformations belong also to organic chemistry.*
851. VARIETY OF ORGANIC MATTER. —
Illustrate the . f .
variety of or- The variety of organic matter is almost
garde matter. wjthout limit. Every color of every dye,
every flavor of every sweet or bitter herb, every gum,
* Carbonic acid, water, bone ash, and some other substances, are ex-
ceptions to the above rule, and are commonly treated under the head
of inorganic chemistry. Though often produced from animal and
vegetable substances, they also exist, ready formed, in nature, or may
be readily made from organic or mineral matter.
336 ORGANIC CHEMISTRY.
and every resin, is a distinct organic substance. In
the animal body, also, there is scarcely less variety.
The fluids which dissolve the food, the blood which
distributes it throughout the body, the color which tints
the skin aiid hair, and the milk "which nourishes the
young, are a few of the substances which it includes.
852. MATERIALS OF VEGETABLE GROWTH.
What arc the „-..,' - .
materials of With the exception of the small proportion
°^ mmeral matter which is derived from
the earth, the materials out of which all
animal and vegetable matter is formed, are but few in
number. Carbonic acid, ammonia, and water, are all.
These are partly obtained from the air, and partly from
the earth. Carbon, hydrogen, oxygen, and nitrogen,
are the four elements which enter into their compo-
sition.
What is re.- 853. CONVERSION OF THE MATERIALS. -
workable in A vital force slumbers within the seed,
the new pro- , . ,,
parties which which in germination wakes to life. Call-
result ? jng to -tg aj^ faQ ijgjlt an(j Warmtl1 Of the
sun, it weaves, as it were, out of the scanty mate-
rials which have been mentioned, all of the varied
forms of vegetable matter. Among the materials, one
is a tasteless solid ; the rest are tasteless gases. Yet
sweet, sour and bitter flavors result from their combi-
nation, with all the other boundless variety of the or-
ganic world.
854. SIMILARITY OF COMPOSITION. — Yet
Give some in- ,
stances of aim- more remarkable than the limited number
il^olidth of elemeilts> fr°m which so great a variety
di/f rent pro- of organic substances is formed, is the
per similarity of composition in many sub-
GENERAL VIEWS. 337
stances, which are yet so widely different in their pro-
perties. Vinegar differs from alcohol, for example, in
containing a little more oxygen and a little less hydro-
gen, while the proportion of carbon in each is the same.
Ether, also, contains the same amount of carbon as the
alcohol from which it is formed, with a little less hydro-
gen and oxygen. Yet these substances are all widely
different in their properties.
Mention some 855. IDENTITY OF COMPOSITION. Most
™hich™r*difi remarkaole °f all> and at first view incred-
ferent in pro- ible, is the fact that many organic sub-
tdenticaHn stances which are as widely different in
composition. properties as any which have been named,
are still precisely the same in their composition ; not
alone containing the same elements, but containing
them in precisely the same proportion. The most careful
chemical investigation finds no difference of composition
in wood, gum, and starch. The sugar which sweet
milk furnishes, arid the acid which exists in the sour,
contain identically the same proportions of the same
constituents. The oils of turpentine, lemon and pepper,
so different in their taste, contain an equal quantity of
carbon and hydrogen, without the addition of any
third substance to either, to account for the difference.
Truly, organic chemistry has brought us to results as
strange as the dream of the alchemist, who believed
that lead might be converted into silver, and copper
into gold. All such substances, possessing the same
composition with different properties, are called iso-
meric bodies — a term signifying their similarity of com-
position.
15
338 ORGANIC CHEMISTRY.
856. ARRANGEMENT OF ATOMS. — At a loss
How are the
above facts ac- for any other way of accounting for such
counted for? difference of properties, we are compelled
to believe that it is because of difference of atomic
arrangement. We have seen, in the case of iodide
of mercury, mentioned in a former chapter, that a
mere touch, which produces motion and re-arrange-
ment of its atoms in smaller groups, at the same time
changes the color of the compound from yellow to red.
Now the molecule of lactic acid, although containing
the same relative proportion of all of its constituents,
is smaller than the molecule of sugar of milk. It con-
tains six atoms of carbon, six of hydrogen, and six of
oxygen. The molecule of sugar of milk contains
twelve of each, and can therefore furnish material to
make two of acid, as it does in the souring of milk.
And we may suppose that the change from sweet to
sour is owing to this subdivision of the molecules.
857. There are other cases of identical
How is diver- . , . -, • -, • T rr
sity of prop- composition, in which there is no difference
€countedfor whatever in the size of the molecule, or the
when there is number of atoms which enter into its corn-
no difference . . . ., .,
of compost- position. This is the case with the oils of
tionor size? turpentine, lemon, and pepper, and perhaps
with wood, starch, and sugar. The molecules of each
are composed, not alone of the same proportion of the
elements which enter into its composition, but, as there
is reason to believe, of the same number of atoms of
each. We are therefore compelled to look for the differ-
ence which shall account for their peculiar property, in
a different arrangement of atoms, inside of the mole-
GENERAL VIEWS. 339
cules themselves. A more satisfactory idea of this sub-
ject can be obtained after reading what follows, on the
subject of organic radicals.
Give an in- 858. SUBSTITUTION. — A still more re-
stance of sub- markable evidence of the influence of ar-
stitution titat
does not affect rangement or grouping of atoms, remains
P10PC^ to be mentioned. The internal arrange-
ment of a molecule remaining the same, it seems to
matter little, in many cases, of what it is composed.
Hydrogen may even be replaced by chlorine, a body
as widely different from it as anything which nature
affords. By this means, ordinary acetic acid is con-
verted into chloracetic acid, a body remarkably anal-
ogous in its properties to the acid from which it is
formed. From this, again, by withdrawing the chlo-
rine and restoring the hydrogen, the original acetic acid
is reproduced.
859 TYPES. — The last example will
What in said . •,
of the doctrine serve as an illustration of the doctrine of
cnemical types and substitution, which cer-
tain chemists have endeavored to extend to
all organic bodies. It has been maintained that the
properties of these bodies depend solely upon arrange-
ment, without any reference to the nature of the ele-
ments combined. The fact is, that while there are
many cases of such substitution without essential
change of properties, it is always attended by more or
less modification of the original substance. The
properties of a compound are therefore to be regarded
as depending neither upon the nature or arrangement
of atoms alone, but upon both causes combined. The
340 ORGANIC CHEMISTRY.
type, is the group which remains permanent, while the
individual atoms which compose it are changed.
860. COMPOUND RADICALS. — Many or-
Ilhistrate the '
subject of com- game bodies, although compounds, com-
Pcahd Tadl' Port themselves as if they were elementary
substances. Some of these are, as it were,
metals ; forming oxides, chlorides, and salts, like the
true metals, which have already been considered.
Others correspond more nearly to the metalloids. Each
being organic, and like a metalloid, the root of a whole
series of compounds, is called an organic radical. The
term radical is sometimes applied, for similar reasons, to
chlorine, bromine, and other elementary substances.
As the organic substances above referred to, are com-
posed of different elements, they are called compound
radicals.
861. ILLUSTRATION. — A molecule of or-
ple of acom- dinary ether is composed of four atoms of
poundradical carborij five of hydrogen, and one of oxy-
gen. But the carbon and hydrogen atoms are grouped
together, forming a compound radical called ethyle,
with which the oxygen is then com-
bined to form ether or oxide of ethyle.
Alcohol, as illustrated in the figure, is
the hydrated oxide of this radical. Al-
dehyde, a substance to be hereafter more particularly
described, has the same composition as alcohol, with
the exception that two atoms of hydrogen have been
removed from the radical. Acetic acid is formed from
aldehyde by the re-placement of the removed hydrogen
by the same number of atoms of oxygen. Ethyle itself
may be prepared indirectly from the oxide, as potassium
HOMOLOGOUS SERIES. 341
is obtained from potassa or oxide of potassium, although
by a different process.
What were the 862. It is but a few years since the
grounds of be- metf10(i of producing ethyle was discovered,
hef vn the ex- & J
of but chemists believed in its existence al-
most as confidently before, as now. They
co-eery? reasoned that ether, which possesses the
properties of an oxide, must have its radical, as Sir
Humphrey Davy reasoned that potassa, soda and lime,
must each contain its metal.
863. HOMOLOGOUS SERIES. — Certain of
What are ho- «.<>'•'•«
moiogous these compound radicals sustain to each
other a curious numerical relation. They
form a series in arithmetical progression, differing from
each other in composition, by a common difference.
Two atoms of carbon with two of hydrogen forms the
common difference of the series referred to. Methyl,
the radical of wood spirit, begins the list with two atoms
of carbon and three of hydrogen. Ethyle follows — its
composition being expressed by the addition of the
common difference to the last. Margaryl, a radical
contained in certain fats, is the seventeenth member of
the series. Each of these radicals has, like ethyle, its
own oxide or ether, its hydrated oxide or alcohol ; also
its aldehyde and its acid. A series of radicals, ethers,
alcohols, aldehydes and acids, each in arithmetical pro-
gression, is thus produced. Such series are called ho-
mologous.
864. PRODUCTION. — There are many saps
How are the * *-
different mem- in most of the series, but the law of their
bersproduccd? progression is so we]1 established, that no
342 ORGANIC CHEMISTRY.
doubt can exist as to the probable production of the
missing members. The most complete of the series is
given in the Appendix. Several of its more simple
members may be produced by the action of nitric acid
upon those higher in the scale. The acid has the effect
of burning out part of their carbon and hydrogen, and
thus reducing the relative proportion of their constitu-
ents.
865. PROGRESSION OF PROPERTIES. —
What is said
of the relation There is also a similar progression of pro-
°~ PertieS in the SerieS' The earlier menl-
bers of the alcohol series are highly vol-
atile liquids; the later are solids at ordinary tempera-
tures. Each increase of the relative properties of car-
bon and hydrogen produces a substance which is more
fixed. In other words, the boiling point is higher for
each successive member. The difference for each is
about 34° F. The density of the vapors increases by
a similar law. It is thus possible to predict, with accu-
racy, the boiling point and density of vapor in members
of the series which have not yet been discovered.
866. RADICALS NOT ISOLATED. — The
Have all or- .
ganic radicals larger part of the organic radicals have not
been isolated? yet ^een isolated. They are only known
in their compounds, and the belief in their existence
rests on the reasoning which has been given in a previ-
ous paragraph. This is regarded by chemists as abun-
dantly sufficient for giving them names and places
among chemical compounds. It is still, however, to
be borne in mind, that the reasoning is not of the nature
of absolute demonstration.
SUBSTITUTIONS. 343
Mention some > SUBSTITUTION COMPOUNDS. It Was
instances of stated, in a previous paragraph, that there
the substitu- ., , ,, . . -
tionofradi- are many cases of substitution of the ele-
cals' ments for each other, without material
change of properties. Certain cases of substitution of
organic radicals for the elements remain to be men-
tioned. Theoretically considered, they form, perhaps,
the most important discoveries which have for years
been made in organic chemistry. Ammonia, as the
student is already informed, is a volatile base whose
molecules consists of one atom of nitrogen and three
atoms of hydrogen. For one of these atoms of hydro-
gen, a molecule of the radical ethyle may be substituted,
without very materially affecting its properties. The
new ammonia thus formed is, like the first, a volatile
base resembling the first so nearly in odor that it must
have been repeatedly mistaken for it when accidentally
produced. It is, however, a liquid at ordinary temper-
atures. This body has received the name of etliyla-
mine. Methylamine is another body of the same series,
produced by the replacement of two of the atoms of am-
monia by the radical ethyl. Triethylamine is a third.
By a similar substitution of hydrogen in ammonia by
the radical methyl, another series is produced. Other
radicals yield other series.
868. OTHER SUBSTITUTIONS. — There are
Mention other
cases of sub- other bodies which result from the substi-
stitution. tution of different radicals or the metal pla-
tinum, for the different atoms of hydrogen. Substitu-
tions may even exist in the substituting radicals. All
of these bodies retain the type of ammonia, and all of
344 ORGANIC CHEMISTY.
them have basic properties. Many of them are strikingly
similar to ammonia in odor and other properties. These
substitution compounds afford still further evidence of
the influence of arrangement of atoms and molecules
in determining the character of chemical compounds.
Many of these bodies differ very widely in their com-
position, and are yet closely allied in their properties.
The methods of producing the substitutions above
mentioned, are not of interest to the general student.
A general notion of substitutions may be obtained from
the double decompositions with which the student is
already familiar.
ORGANIC CHEMISTRY.
345
CHAPTER II.
VEGETABLE CHEMISTRY.
What is mid 869. GERMINATION. — Before the process-
of germination es of transformation of the materials of the
and the chan- ...
ges which at- earth and atmosphere into the innume-
rable products of the vegetable world can
commence, a rudimental plant must be developed from
the seed. The seed itself contains the
materials for its production. These are
principally starch, and gluten,* or the other
substances analogous to each, which have
already been described. The first stage in
the process is the absorption of moisture
and oxygen from the air, and the conse-
quent production of diastase^ This sub-
stance has the remarkable property of con-
verting starch into sugar, and rendering soluble all of
the remaining gluten of the seed. By the appropria-
tion of these materials, which have been stored up for
it in the seed, the germ is developed into a perfect
plant. It lets down its root into the soil in search of
* Gluten is the stringy substance which remains on removing the
starch from dough by long continued kneading. It is further described
in a subsequent paragraph.
f Diastase is an oxydized gluten, which is always produced from
gluten in germination.
15*
346 ORGANIC CHEMISTRY.
mineral food, and lifts its leaves into the atmosphere,
from which it is to derive its principal nourishment. At
this point, the true vegetative process commences.
870. VEGETABLE NUTRITION. — Every
What is the
office of leaves leaf is a net to catch the fertilizing con-
°^ p a stituents of the air, and appropriate them
to the uses of the plant. It drinks them in through its
countless pores, while the root supplies the remaining
material and sends it upward in the rising sap. All of
these materials meet in the leaf, which is the labora-
tory in which their conversion into vegetable matter is
to be accomplished. The light and heat of the sun
co-operate with the vital forces of the plant, in the
transformation which succeeds.
871. Whatever proportion of carbonic
evohed from acid and water may be employed as the
plants? raw material, it is obvious, by comparison
of their composition with that of vegetable substances,
as hereafter given, that the oxygen is furnished in
larger quantity than is required. Water alone supplies
a sufficient quantity of this element, and more than
enough for most substances that are to be formed. As
the process of transformation proceeds, this gas is there-
fore constantly thrown off into the air. It is the refuse
of the manufacture. Inasmuch as the evolution takes
place from the leaf and other green parts of the plant,
it is reasonable to suppose that this is the point where
the process of transformation is principally conducted.
The gum, sugar, or other materials produced, are dis-
solved in the descending sap, and transformed into
other products, in the course of their circulation.
OFFICE OF THE ROOT. 347
872. The agency of the leaves of
the ,
of plants in absorbing and decomposing car-
ro- bonic acid> may be illustrated by the simple
ved by experi- means represented in the figure. A glass
funnel being filled with leaves, and slightly
carbonated water, is exposed to the sun.
Oxygen gas is gradually evolved from
the absorption and decomposition of the
carbonic acid, and collects in the tube
of the funnel. The oxygen may be
tested by the usual means. The inversion of the fun-
nel without loss of its contents, is easily effected, by
covering it with a saucer and turning it in a pail of
water.
873. For certain transformations of ma-
What trans- . . .
formations oc- terial in plants, the evidence is entirely con-
purin plant*? clusiye> The sugar beet and tumip are
sweetest in the earlier stages of their growth. Later
in the year they become hard and fibrous. This change
is undoubtedly owing to the conversion of the sugar,
contained in the sap, into woody fibre. In the ripening
of grain, the sweet and milky juice of the young plant
is converted into starch. Both hay and grain, which
are harvested too late, are deteriorated by the conver-
sion of a portion of their starch and sugar into wood.
In the ripening of fruits a portion of their acid is con-
verted into sugar, as is evident from their change of flavor.
874. OFFICE OF THE ROOT. — The agency
How w the ac- of fae roots m supplying the plant with its
tion of the
roots'illus- mineral food, may be illustrated by the
apparatus represented in the figure. In
preparation for the experiment, a glass fun-
348 ORGANIC CHEMISTRY.
nel is tightly covered with a piece of blad-
der, and then filled with a solution of sugar
or salt. A tube is then fitted, air tight, to
its extremity. A glass vial, from which
the bottom has been removed, may be sub-
stituted for the funnel in this experiment.
On placing the apparatus, thus arranged, in a
vessel of water, the latter penetrates the ani-
mal membrane, and adds itself to the con-
tents of the funnel. The flow of the water
is called endosmose, and is made apprecia-
ble to the eye by the rise of liquid in the tube. An
cxosmose, or flow of a small portion of the contents of
the funnel outward, takes place at the same time.
875. The phenomenon exhibited in the
Explain the .
phenomenon above experiment, is to be accounted for
of endosmose. by the difference of capil]ary attraction in
the bladder for the two liquids. The spongioles, with
which the extremities of the roots are provided, being
filled with solutions of gum and sugar, act similarly
upon the liquids of the soil. The endosmotic action,
above described, is not confined to the roots of plants,
but occurs in all their organs, through the walls of the
minute cells of which they are composed. In connec-
tion with the transpiration of water from the leaves,
it is probably the principal cause of the circulation of
the sap. The relation of the plant and soil is further
considered in a subsequent chapter.
876. CONSTITUENTS OF PLANTS. — Amoner
Mention some
of the more the more important of vegetable substances
ffSea^Ve' are wood, starch, sugar and gluten. Woody
stances. fibre forms the mass of the plant ; starch
WOOD. 349
and gluten collect in the seed j while sugar and gum
exist principally in the sap and fruit, or exude from
the bark.
WOOD.
Mention dif- S77' W°ODY FIBRE.— Woody fibre, of
ferent forms which the fibrous threads of cotton or flax
of ivoody fibre , j /r
^-its com- maY serve as an example, is composed of
position. carbon, hydrogen and oxygen. Its mole-
cule contains twelve atoms of carbon, to ten of hydro-
gen and ten of oxygen. It constitutes the solid mass
of all vegetable organs, whether hard and firm, like
the fibre of the oak ; soft, like the pulp of fruits ; or
fibrous, like cotton and flax. In one or the other of
its forms it therefore serves us for shelter, clothing and
food. It forms in plants the cells in which the vege-
table juices are contained, and the veins or pores
through which they circulate ; and has thence received
its name of cellulose. In wood, these cells are often
lined or filled with a substance of similar composition,
to which the name of lignin has been given.
878. CHANGE BY HEAT — GAS, CHAR-
changed by COAL, ETC. — Under the influence of
heat? a high temperature, without access
of air, wood is converted into charcoal, water,
gases, wood vinegar, and tar. It is to be observed
that this change is the simple result of a re-ar-
rangement of the atoms of the wood itself, with-
out the help of additional oxygen or other ele-
ments. It is a most remarkable instance of va-
350
ORGANIC CHEMISTRY.
riety as produced by varied arrangement. The new
substances are, as it were, different patterns, woven
from the same colored threads. The gases, of which
carbonic acid, light and heavy carburetted hydrogen
are the principal, have been already described. Wood
vinegar and wood tar form the subjects of subsequent
paragraphs. An excess of carbon remains behind as
charcoal. The process is called dry distillation. The
decomposition may be illustrated with saw-dust, in a
test tube, as previously described.
879. SIMILAR CHANGE IN NATURE — PEAT.
Mention a si- .
milar change Peat is formed by the decay of vegeta-
tn nature. j}je matter un(}er water. The green slime
which forms, in the summer, upon stagnant water, is
composed of minute plants. These die, each season,
and sink to the bottom, until, in the course of years or
ages, vast accumulations of vegetable matter are the
result. By their partial decay or putrefaction under
water, they are converted into peat. The process is
analogous to that of dry distillation, and the products
similar. Carbonic acid and carburetted hydrogen gases
are evolved, while a solid residue of peat remains be-
hind. It may be regarded as a half-formed charcoal.
Peat contains, in addition to its carbon, a little hydro-
gen and a still smaller proportion of oxygen. The
carbonic acid evolved in the above process, often makes
its way to the surface, at some neighboring locality,
in the form of mineral springs.
880. BITUMINOUS COAL. — The formation
How is bitutm- . , . , .
nous coal 01 bituminous and anthracite coal is a con-
formed? sequence of a similar decay of vast accu-
WOOD. 351
mulations of vegetable matter, which have been buried
in the earth during previous ages of its existence. As
a consequence of pressure, the material takes a different
form from that already described, and is found, after
ages have elapsed, as bituminous coal.
Howisanthra- 881. ANTHRACITE COAL. — Where bitu-
dte formed? mous coai has been subjected to great heat,
more carbon and hydrogen are expelled, and anthracite
coal remains. A similar change takes place where bi-
tuminous coal is heated by artificial means. The coke
which remains, is, like anthracite coal, nearly pure car-
bon.
882. PRODUCTION OF HUMUS. — Humus,
What is hu-
mus? How is or the vegetable mould of forests, is formed
it produced? by the decay of wood Qr yegetable matter
in the air. Such decay is a species of slow combus-
tion. The carbon is more slowly consumed than the
other constituents. The vegetable mould or humus
which remains after the partial decay, is, therefore, like
peat, much richer in carbon than the material from
which it was produced. It is variable in composition,
according to the progress of the decay. The access
of oxygen from without being unlimited, it is found to
remain in equal atomic proportion with the hydrogen.
What is the 883. WHITE ROTTEN WOOD. White
composition of roUen wood, which forms in stumps and
wliite rotten
wood? the interior of trees where there is abun-
dant moisture and deficient access of air, has a different
composition. The water present becomes chemically
combined, and the product may be regarded as differ-
ing from the former, somewhat as a hydrated oxide
differs from the oxide itself.
352 ORGANIC CHEMISTRY.
8$4. PREVENTIVES OF DECAY. — The ten-
How may the
decay of wood dency of wood to decay is checked by
be prevented? ^ and ^Q b certain salts> por
this purpose, corrosive sublimate and chloride of
zinc have been chiefly used. The process of impreg-
nation with metallic salts is called kyanizing.
885. INCOMBUSTIBLE CLOTH. — Cotton
How is cloth IT- • T • ^ i
rendered in- cloth immersed in a solution or phosphate
combustible? Qf magnesia js thereby rendered incombus-
tible. Silicate of potassa is also used on wood for the
same purpose.
886. EFFECT OF SULPHURIC ACID ON
What is the
effect of sul- WOOD. — Sulphuric acid chars or blackens
Pwood?aCid°n wood by abstracting a portion of the
dxygen and hydrogen which it contains.
The carbon is then left in excess, with its characteris-
tic color. This action of sulphuric acid is a conse-
quence of its strong affinity for water, the elements
of which it appropriates from most organic substances.
Dilute sulphuric acid has another remarkable effect, to
be hereafter mentioned.
887. EFFECT OF NITRIC ACID. — Nitric
What is the -11,,
effect of nitric ac id gradually consumes wood and other
add on wood? organic matter> as effectually as if they
were burned by fire. The final products of its action
are also the same as those of ordinary combustion.
This action is accompanied with the evolution of orange
fumes, as when the same acid acts on metals. The
first effect of nitric acid is to stain wood yellow ; for
which purpose it is sometimes employed. Nitric acid
may also be made to combine with woody fibre, form-
ing gun cotton.
WOOD. 353
What is the 888. EFFECT OF MURIATIC ACID. — This
acid aci^ has no very striking effect on wood
on wood? or other organic substances. But chlorine
decomposes and destroys them ; principally, in conse-
quence of its affinity for hydrogen, as before explained.
What effect ^89. EFFECT OF ALKALIES. - Alkalies
have alkalies have the effect of hastening the decompo-
on wood and . .
similar sub- sition of organic substances. This effect
is, in part, due to the fact that they promote
the absorption of oxygen from the air. Paper or cloth
in contact with lime or potash, is found to lose its
strength speedily, and finally to crumble away. The
theory of this action has already been given in the
paragraph on nitrate of lime. Where the atmosphere
is excluded, it would seem, from certain experiments,
that lime has an opposite effect, and rather retards than
promotes the decomposition of organic matter.
What differ- 890. W°OD VINEGAR. — The acid pro-
cnt substances duct, as obtained in the dry distillation
are contained . , . , . . , ,
in wood vine- of wood, contains, beside acetic acid and
gar? water, a sort of alcohol, called wood-
spirit, and an oily, colorless fluid called kreosote. The
latter has the odor of smoke, and has the same
effect in preventing the putrefaction of animal sub-
stances. The effect of smoke is owing, indeed, to the
kreosote which it contains. A dilute solution of this
oil in water, is used in medicine and for curing meats.
891. WOOD TAR. — Wood tar is a mix-
cl?areSlconan' ture of various oils, and volatile crystalline
tained in wood solids composed principally of carbon and
hydrogen. Kreosote, which is also ob-
354
ORGANIC CHEMISTRY.
tained from wood vinegar, is one of the oils. Another
of them, called eupion, has a pleasant odor, somewhat
similar to that of the flower called narcissus. Pittacal,
a beautiful blue coloring matter, resembling indigo, and
paraffine, resembling spermacetti, are also obtained from
tar.
892. COAL TAR. — Coal tar
Jances^r'e is produced from bituminous
contained in coal, in the process of mak-
coal tar ? ... .
ing illuminating gas. It con-
sists of numerous liquid and solid hydro-
carbons, produced by the decomposition
of the coal from which it was formed.
Among them is napthaline, like camphor
in appearance, and dissipated, like this sub-
stance, by exposure to the air. Others are
mentioned in the next paragraph. Coal tar, mixed
with chalk, or other material, is used as a cement, and
also as a material for covering roofs.
893. USEFUL PRODUCTS FROM COAL
useful pro- ' TAR- — The first product of its distillation,
ducts of coal is a light oil, commonly known as benzole.
This may be substituted for spirits of tur-
pentine, for a great variety of uses. Another heavier
oil, which is obtained from it, is used as a solvent of
india-rubber, and also for lubrication and illumination.
In Europe, the pitchy mass, which remains on dis-
tillation, is employed in moulding refuse coal dust
into cakes, to be used as fuel. The light oil is also con-
verted by the action of nitric acid, into an artificial es-
sence, similar to that of bitter almonds, used exten-
WOOD. 355
sively for scenting soap. -Its vapor, mixed with air, is
also burned as gas. The heavy oil may be converted
by a different action of the same acid, into beautiful
lemon-colored crystals of carbazotic acid, a substance
now used in France as a yellow dye for silks and wool.
894. OILS FROM COAL. — The oils may
How are oils ,,';"",
produced from be directly produced from bituminous coal
itself, and in much larger quantities than
from tar, by avoiding the high temperature to which
coal is subjected in the production of tar and gas.
The production of oils by this means promises to
be a very important branch of industry.
895. GUN-COTTON. — This material, so
How is gun-
cotton pre- entirely harmless in appearance, has an
pared? explosive energy superior to that of gun-
powder. It may be prepared by immersing ordinary
cotton, for the space of five minutes, in the strongest
nitric acid. It is then to be washed thoroughly, and
dried at a moderate heat, for fear of explosion. The
material is found to have lost a certain portion of its
oxygen and hydrogen, in the form of water, and to
have assumed nitric acid, in its place. It is not how-
ever changed in its appearance. A mixture of nitric
acid with two-thirds of its volume of oil of vitriol, is
found to be preferable to pure nitric acid, in the above
experiment. The oil of vitriol assists in abstracting
from the cotton the water which it is desired to replace
by nitric acid. Gun-gotton is also called pyroxyline.
Similar compounds, which are less explosive, may be
prepared from sugar and starch.
356 ORGANIC CHEMISTRY.
896. USE OP GUN-COTTON, — Gun-cotton.
What is said
of Us proper- is not likely, for several reasons, to super-
cede gun-powder, for use in fire-arms. It
is much more expensive, and so suddenly explosive as
often to burst the barrels in which it is fired. Its ex-
plosive force depends, like that of gun-powder, on a
sudden combustion throughout its whole substance,
and consequent evolution of a large volume of mixed
gases and vapor. Of these, carbonic acid, nitrogen, and
aqueous vapor are the principal.
897. GUN-COTTON SOLUTION — COLLODI-
What in collo-
dion ? How is ON. — Gun-cotton dissolves in ether, form-
ing a syrupy liquid, which, on evapora-
tion, leaves behind a transparent, tenacious film. It is
used, to some extent, in place of ordinary court-plaster,
for covering wounds and protecting them from the air.
HowmayWood 898' W°°D CONVERTED INTO SUGAR.—
be converted Wood may be converted into sugar, by caus-
ing it to combine, chemically, with four ad-
ditional molecules of water. This addition gives it the
precise composition and properties of grape sugar, and,
in fact, converts it into that substance. Poplar wood is
found best suited for the purpose, and can be made to
yield four-fifths its weight. To effect the conversion,
the wood is first reduced to saw-dust, then moistened
with somewhat more than its own weight of oil of vit-
riol, and left to stand for twelve hours. Being subse-
quently pounded in a mortar, the nearly dry material
becomes liquid. It is then boiled with addition of
water, and the transformation is completed. It only
remains to remove the sulphuric acid, and evaporate
STARCH. 357
the syrup. The former object is effected by the addi-
tion of chalk and subsequent nitration, and the latter,
as usual, by boiling
TT 899. WOOD CONVERTED INTO GUM.
How is wood
converted into If the boiling be omitted in the above pro-
cess, the woody film takes the form of a
gum, called dextrine, of the same composition as the.
wood itself, but soluble in water. Linen, or cotton
rags, or paper, may be converted into sugar, or gum,
by the same process. The sugar obtained is the same
as that contained in grapes, and is therefore called
grape sugar, and also glucose. It differs, somewhat,
from ordinary cane sugar, as will be hereafter explained.
STARCH.
WJiatissaid ^00. DESCRIPTION. — Starch is identical
of the compo- in composition with wood and gum. It
sitlon and i -i •
structure of consists of minute enveloped grains, which
burst and discharge their contents when
swollen by warm water.
Where is 901. — OCCURRENCE. — Starch isfoiuid
starch found? jn abundance in most grains and other
seeds ; in the tubers of the potatoe plant ; in many
fruits, and in the pith of certain trees. In greater or
less quantity, it is contained in all substances of vege-
table origin which are used as food. Horse chestnuts
contain 12 per cent, of starch, and have been used in
Europe for the production of flour.
902. STARCH FROM POTATOES. — Starch
How is starch .
prepared from is prepared from rasped potatoes, by wash-
potass/ ing them Qn a seiye> Th£ water becomes
358 ORGANIC CHEMISTRY.
%
milky, as it passes through, from the fine starch grains
which it carries with it. These are allowed to settle,
and being collected and dried, are brought into com-
merce as potatoe starch. A cotton-cloth may be sub-
stituted for the seive in this experiment.
903. STARCH FROM WHEAT. — If wheat
How is starch
made from, flour is moistened with water, and exposed
to the air, it enters into a putrefaction which
destroys, in the course of a few days, the
other constituents, and leaves the starch un-
affected. The residue being then washed
and dried, the manufacture is completed. Io-
dine may be used as a test for starch, as described under
the head of iodides. Gums and woody fibre, although
of the same composition, are not similarly affected.
904. CONVERSION OF STARCH INTO
How is starch ... 1
converted into SUGAR. — Starch, like woody fibre, may be
converted into sugar through the agency
of sulphuric acid. A dilute acid containing only j\ of
its volume of oil of vitriol, is brought to the boiling
point, and the starch then added by degrees while the
boiling continues. A half hour or a little more suffices
for the conversion. An infusion of brewer's malt has
the same effect as the dilute acid. The sulphuric acid
is then to be removed, and the syrup concentrated as
before described. The sugar in this case also is grape,
and not cane sugar. Such sugar is manufactured largely
in Europe for adulterating cane sugar. In England
its manufacture is prohibited by law.
905. CONVERSION OF STARCH INTO GUM.
How is starch ,-»,--. , , •
transformed By keeping the liquid near to the boiling
into gum? point, without actual boiling, the gum
SUGAR. 359
called dextrine, is obtained in the above process, instead
of sugar. It may also be prepared by roasting starch,
carefully, with constant stirring, until it acquires a
brownish yellow color. This gum is used largely in
calico printing, for thickening colors. It is also used in
making the so-called " fig-paste," and certain other
kinds of confectionery. The composition of starch
and gum is precisely the same.
906. GUM. — Gum arabic. and the sum
What is said . . . . .
of natural of fruit trees generally, is identical in com-
gum*l position with woody fibre and starch.
They are either soluble, like gum arable, in water, or
swell up with it to form a thick paste, like gum traga-
canth. The substance called pectine, which causes
the juice of currants, and other fruits to stiffen with
sugar into a jelly, is also similar to the above sub-
stances in composition. All of these bodies, like wood
and starch, are convertible into sugar by the action of
sulphuric acid.
SUGAR.
GRAPE SUGAR- — The production
grape sugar of this substance from wood and starch has
already been described. It does not exist
in the juice of grapes, as its name would imply. The
sugar of the grape and other acid fruits, contains two
molecules less of water. It is spontaneously converted
into true grape sugar or glucose, and found in incrus*
tat.ons upon the surface of the dried fruit. Those
fruits and trees which have but little acid in their
360 ORGANIC CHEMISTRY.
juice or sap, commonly contain cane sugar. The
sweetness of honey is due to grape sugar. This va-
riety is much Jess valuable than that of the cane, from
the fact that it has but little more than one-third of its
sweetening effect.
908. CANE SUGAR. — The sugar in com-
Whot is said . . . . ' ,
of the compo- nion use is principally derived from the
sugar cane> an(l thence receives its distinc-
trndMt
artifidal pro- tive name. It differs in its composition
duction f f -i -i •
from starch, wood, and gum, in containing
a single additional molecule of water, while grape sugar
contains four. It would seem from this com-
position, that it would be more easily produced
by artificial means, from starch and similar
substances. But this is not the fact. No
modification of the process above described,
has as yet been devised by which starch and wood can
be induced to take one additional atom of water, in-
stead of four. Such a process would be a discovery
of the greatest importance, as it would enable us to con-
vert our potatoe and grain fields at will, into sugar
plantations, and make us independent of foreign sup-
plies. The figure represents a crystal of cane sugar.
The form belongs to the fourth system.
909. OCCURRENCE. — Cane sugar is
What are the . .
principal principally produced from the sugar cane,
from beets' and the American maple. But
it is contained in smaller quantity in the
sap of most plants, and in all fruits and vegetables
which are not acid to the taste. The production of
beet sugar in Europe, in 1850, was estimated at 190,000
SUGAR. 361
tons. That of cane sugar in cane growing countries
is incomparably greater.
910. PRODUCTION. — In manufacturing
How is cane , .
sugar pro- sugar from the cane, the juice is first pressed
out, between heavy iron rollers ; then clar-
ified, and finally boiled down until it will crystalize on
cooling. The granular crystals form the raw sugar ;
the drainings, molasses. Lime is the principal agent in
clarification. Its first effect is to neutralize the acid of
the juice, which, as before seen, would gradually con-
vert the cane sugar into grape sugar, and thus injure
its quality. It also precipitates, with other impurities,
the gluten, which, as will be hereafter seen, tends to
produce more acid. The methods of producing sugar
from the beet and maple are essentially the same. The
final purification of sugar by bone black has already
been described.
911. MOLASSES. — A large portion of
How may mo- . .
lasses be con- sugar is ordinarily lost in the form of mo-
vertedinto lasses, from which it cannot be made to
sugar f
separate by crystallization. This is owing
to the presence of impurities not separated by clarifica-
tion, which interfere with the process, in a way not per-
fectly understood. A method has recently been con-
trived of avoiding the loss, and thus largely increasing
the product of the beet and cane. Baryta added to the
syrup, combines with the sugar, and takes it to the
bottom of the vessel, as a solid compound of sugar and
baryta, while the impurities remain behind. This pre-
cipitate is then removed and diffused in water. Car-
bonic acid being added, combines with the baryta, and
16
362
ORGANIC CHEMISTRY.
leaves the sugar to form a pure and crystallizable syrup.
Another method of increasing the product of sugar has
been described in the section on sulphurous acid.
How is alcohol
produced from
ALCOHOL.
912. PRODUCTION FROM SUGAR. — By
i -• • •
the addition of brewers' yeast or some si-
milar ferment to sugar, it is gradually con-
verted into alcohol. Two molecules of water are sepa-
rated in the process. One-third of the carbon and two-
thirds of the oxygen which remain, pass off as carbonic
acid gas, while alcohol remains. The yeast enters into
no combination, and furnishes no material in the pro-
cess. It acts merely by its presence to effect the de-
composition, as will be hereafter explained.
Explain the 913. In this process of conversion, each
diagram. molecule of sugar makes two of alcohol, and
four of the acid. The figure repre-
sents a molecule of grape sugar, after
the removal of two molecules of
water. An arbitrary arrangement is
given to the atoms for convenience
of illustration. On striking off
enough carbon and oxygen from the
corners to make the required amount
of carbonic acid, the residue may be supposed to fall
apart into two molecules of alcohol. Alcohol is also
produced from cane sugar by fermentation. The first
stage in the process is its conversion, by yeast, into
ALCOHOL. 363
grape sugar. The latter is then changed into alcohol
and carbonic acid, as above described.
914. COMPOSITION. — The composition
What is the
composition of of alcohol appears sufficiently from the mid-
dle groups of the preceding figure. Accord-
ing to the theory of compound radicals
it is a hydrated oxide of ethyle. The
principal group of the annexed cut,
represents a molecule of the radical ;
the remaining circles stand for the oxygen and water
with which it is combined in alcohol.
915. PRODUCTION FROM POTATOES AND
How is aico/iol
made from po- GRAIN. Wliei'6 molasSCS Or Solution of
sugar is the material used, alcohol is pro-
duced as already shown. But when potatoes and grain
are employed as the material, a previous process is
necessary by which the starch is converted into sugar.
This consists in the addition of bruised malt to the
mashed potatoes or grain. The diastase of the malt,
has the effect of gradually transforming starch into
sugar by its presence, as yeast converts sugar into
alcohol. The mixture being kept at a temperature
of about 140°, in a few hours the transformation is
complete. The starchy mixture has become sweet,
and receives the name of wort. Brewers' yeast and
water being then added to the wort, the conversion into
alcohol commences. This is afterward separated from
the water and refuse fibre of the potatoe or grain by
the process of distillation, described in a subsequent
paragraph.
364 ORGANIC CHEMISTRY.
What is said 916. PRODUCTION FROM ILLUMINATING
of the produc- GAS — Alcohol may also be produced from
tion of alcohol
from olefiant heavy carburetted hydrogen, one of the con-
gas' stituents of ordinary illuminating gas. This
is one of the most remarkable results of modern science.
Most of the processes of organic chemistry consist in
taking apart the complex molecules of organic matter and
reducing them to a simpler form, as was illustrated in the
production of alcohol and carbonic acid from sugar. Na-
ture, for the most part, jealously withholds from man
the power so to direct her forces as to build up arid
produce more complex organic substances by the com-
bination of those of simpler nature. This takes place
as a general rule only under the influence of the vital
forces of vegetable and animal existence, as when the
plant produces sugar from the elements of the atmos-
phere. The case is an exception to the general rule.
Explain its 917. By reference to the central group
production. of tne figure which represents a molecule
of heavy carburetted hydrogen, it will be seen that all
that is necessary to effect its conver-
sion into alcohol, is the addition of
two molecules of water. By long
agitation of the gas with strong sul-
phuric acid, the transference of part of the water which
it holds combined is effected. On subsequent dilution
and distillation, alcohol is obtained from the mixture.
Carbonate of potassa is added in the process of distil-
lation, to diminish the proportion of water which would
otherwise pass off with the alcohol. After repeated dis-
tillation, strong alcohol is thus obtained.
ALCOHOL. 365
918. DISTILLATION OF ALCOHOL. — The
What ^,<< said
of fae presence process of distillation may be illustrated
of distillation? with the simple appals ^presented in
the figure. On heating wine, cider or beer in the test-
tube, its alcohol will be ex-
pelled as vapor and re-con-
densed as a colorless liquid.
The cooler the vial is kept
the more perfect is the condensation. The apparatus
commonly employed in the distillation of alcohol, con-
sists of a large copper vessel in which the fermented
wort is heated, and a long tube called the worm, in
which the vapors are condensed. The worm is made
to wind in a spiral, through a tub of cold water, that
the condensation may be more completely effected.
The spirit pours out at the lower end of the worm,
where it emerges from the tub. It may be strength-
ened by repeated distillation. In order to obtain it
entirely free from water, a highly rectified spirit is
mixed with lime, or chloride of calcium, and re-dis-
tilled. These substances have such affinity for water,
that they prevent its escape as vapor, while they in
no wise effect the distillation of the alcohol. By
this means pure alcohol, or absolute alcohol, is ob-
tained.
Wimtis spir- ^19. USES OF ALCOHOL. — Ordinary
it* of wine? spirits of wine is a dilute alcohol contain-
Mention some .
uses of aico- ing but about seventy per cent. 01 absolute
hol? alcohol. The taste and odor of alcohol
its combustible character, and action as a stimulus, are
too familiar to need further mention. Its density, and
366 ORGANIC CHEMISTRY.
boiling point, are given in the Appendix. It is largely
used in medicine, and as a solvent of oils and resins,
and many other substances which water does not dis-
solve. Medicinal extracts of many roots and herbs,
"cologne," and other perfumed liquids are thus pro-
duced.
What is the ^20. SPIRITUOUS LIQUORS. - SpiritUOUS
source of the liquors contain alcohol in large but varying
different spir- J
ituousli- proportion. They differ in their flavor
according to the material from which they
are produced. Brandy is distilled from wine, rum
from molasses, and whiskey from malt liquors. The
latter name is also given, in this country, to the liquor
made from potatoes, corn, and rye. In Europe, the
latter are more commonly called brandies.
How are wines 921. WINES.— Wines are produced by
produced? the fermentation of the juice of the grape.
On exposure to the air, the gluten of the juice becomes a
ferment, and causes the conversion of the sugar into
alcohol. The addition of yeast is therefore unneces-
sary. This is also true of the juice of the apple, pear,
and other fruits from which fermented liquors are sim-
ilarly prepared.
How is cham- 922. CHAMPAGNE. — Champagne and
pagnemade? other sparkling wines owe their peculiar-
ity to the presence of carbonic acid, in large propor-
tion. This is secured by allowing the last stages of
fermentation to proceed in firmly corked bottles, so
that all the gas which is evolved is retained. Or an or-
nary wine is first produced by the usual process, and
sugar and yeast are then added, to excite a new fer-
mentation in the bottled liquid.
MALT LIQUORS. 367
What is said ^23. ALCOHOL IN WINES. — Wines differ
of the pro- in the amount of alcohol which they
portion of al- .
coholin tain; from five per cent., in the weakest
champagne, to twenty-five, in the strongest
sherry. Those of southern climates are strongest, be-
cause the grapes of those regions contain more sugar
to undergo conversion into alcohol. Most wines also
contain more or less acid and urifermented sugar.
What is said 924. TARTAR. — The acid of wine is
of acid in . ., , . . . ^ . .
\tines? tartanc acid, which exists in combina-
tion with potash in the juice of the grape. It grad-
ually deposits in wine casks in the form of acid tar-
tra'te of potash or cream of tartar. This separaton
of tartar is one source of the improvement of wines,
and more particularly of the rhenish wines, by age.
925. FLAVOR OF WINES. — The wine
What is said .
of the flavors flavor which belongs to all wines, is
owing to the presence, in extremely small
portion, of an etherial liquid called aenanthic ether.
Tliis substance does not exist ready formed in the
grape, but is produced in the re-arrangement of atoms
which takes place in fermentation. Its vinous odor,
when separated from the wine, is most intense. It is
prepared in Europe from grain spirit or cheap wines,
and is used in this and other countries for producing imi-
tations of wines of higher price. Potatoe whiskey is
commonly the basis of these manufactured wines.
Beside the general vinous flavor, different wines, like
flowers, have an aroma, or bouquet, peculiar to them-
selves. These are owing, to other and different flavor-
ing substances, present in still smaller proportion, than
the aenanthic ether.
368 ORGANIC CHEMISTRY.
926. BEER AND ALE. — Beer is the fer-
tfow are malt
liquors pre- merited extract of malted grain. The malt
pare ' is prepared by softening barley in water,
and then allowing it to sprout or germinate. Diastase,
which is formed in the process of germination, con-
verts the starch of the grain into sugar, and thus pre-
pares it for the subsequent process of fermentation.
Yeast and hops are added to the extract of malt, which
is called the wort, to bring about fermentation and
help to give the product flavor. Ale is a similar malt
liquor of different color. Porter is a darker variety of
beer, made from malt which has been browned by
roasting.
927. CONVERSION OF ALCOHOL INTO
How is alcohol . , , , . , .
converted into ETHER. — Alcohol is converted into ether
ether ? ky heating witn o{\ of vitriol. To illus-
trate its preparation, equal
volumes of strong alcohol
and oil of vitriol may be
thoroughly mixed in a test-
tube, and the vapors con-
densed in a cool vial, as J
represented in the figure.
A little sand may be added to the mixture with advant-
age. The vial should be kept cool by means of paper
repeatedly moistened, during the process. The space
between the tube and the neck of the vial should also
be loosely closed with wet paper.
928. EXPLANATION. — Alcohol is, as
Explain the -,*••/•
above re-ac- above stated, the hydrate of the oxide of
tl011' ethyl. Sulphuric acid combines with tho
ETHYL. 369
oxide itself, on heating, forming a bi-
sulphate, and at a little higher tem-
perature, yields it up again, as gaseous
ether or oxide of ethyl. The change
in the alcohol consists, simply, in the loss of an atom
of water. The whole figure represents a molecule of
alcohol ; the lower portion one of ether.
929. PRODUCTION OF ETHYL. — The
How is the -i • i 11
radical ethyl radical ethyl cannot, like many metals, be
procured? directly produced from its oxide. Heat,
or other means, applied to accomplish this object,
destroys the radical itself. But the end may be
reached by a circuitous process. This consists in first
producing from the oxide, an iodide
of ethyl, and then removing the iodine
by a metal. A colorless gas, of the
composition indicated by the hydrogen and carbon at-
oms of the figure, is thus evolved.
930. CONVERSION OF ALCOHOL INTO
How is alcohol
convertedinto OLEFIANT GAS. The production of alcO-
olefiantgas? ^ fr()m olefiant gag hag been described
in the section on hydrogen. The subject is again in-
troduced, for the purpose of illustrating the change, by
reference to the atomic composition of the two sub-
stances. Representing the atom of
alcohol as before, it is converted by
the removal of two atoms of oxy-
gen, and two of hydrogen, into olefi-
ant gas. The composition of this gas is indicated by
the central group of the annexed figure. The ab-
straction of oxygen and hydrogen is effected through
16*
370 ORGANIC CHEMISTRY.
the agency of the sulphuric acid used in the process.
It will be observed that the radical ethyl, which has re-
mained permanent in the changes before described, is
here destroyed, by the abstraction of a part of its hy-
drogen.
What is aide- 931. CONVERSION OF ALCOHOL INTO ALDE-
hyde? HYDE. — Aldehyde is a clear colorless liquid
of a peculiar ethereal odor, produced by the action of
the air or oxygen on alcohol. It is the product of a
partial, slow combustion, or ereme-
causis of the alcohol, and forms the
middle point in the conversion of
alcohol into vinegar. It is for this
reason that it is here introduced.
932. The two atoms of hydrogen,
How is alcohol , . .. , , .
converted into which are burned out m the process, are
aldehyde ? indicated in the figure by smaller inscribed
letters. By the removal, the radical ethyl is converted
into the radical acetyl. Aldehyde is therefore a hy-
drated oxide of acetyl. The characteristic odor of the
substance is often perceived, in the process for making
vinegar. It may also be produced by depressing a wire
gauze upon an alcohol flame, and thereby making the
combustion incomplete.
933. CONVERSION OF ALCOHOL INTO VIN-
ZSZZ&f »»«— If dll«te alcoho1 ;s exposed to the
alcohol into air? it is converted, by oxidation, into ace-
tic acid. Part of its hydrogen having been
burned out to form aldehyde, the oxy-
gen acts further to oxidize the alde-
hyde which has been produced. The
composition of each molecule is such
VINEGAR. 371
as is represented in the preceding figure. It will be ob-
served that the oxygen added is just sufficient to sup-
ply the place of the hydrogen removed in the formation
of aldehyde. The latter substance being a hydrate of
the protoxide of acetyl, acetic acid is a hydrated terox-
ide of the same radical. The presence of yeast or
some other similar ferment, is essential in the produc-
tion of vinegar, as well as in that of alcohol.
Describe the 934. PROCESS OF MANUFACTURE. A
process. few years since, vinegar was exclusively
produced by the souring of .wine or cider. At pres-
ent, large quantities are made from alcohol, by diluting
it with water, adding a little yeast, and then exposing
it to the action of the air. This is best accomplished
by allowing the diluted alcohol to trickle through shav-
ings, packed in well ventilated casks. A few passages
through the cask suffices to convert the liquid into
vinegar. The addition of yeast is unnecessary in pro-
ducing vinegar from cider or wine, as these liquids con-
tain a substance which acts as a ferment. The vapor
of alcohol may be readily converted into acetic acid
by contact with platinum black. The property of pla-
tinum to produce oxidation in similar cases, has been
already explained.
935. CHLOROFORM. — Chloroform is best
Howischloro- . ......
formprepar- obtained by distilling pure alcohol with
water and bleaching powder. Its mole-
cule consists of two atoms of carbon, and
one of hydrogen, combined with three of chlorine. The
carbon and hydrogen atoms are regarded as more inti-
mately combined to form the radical formyl. Chloro-
372 ORGANIC CHEMISTRY.
form is therefore a terchloride of this radical. It is
a colorless and volatile liquid, of a peculiar, sweetish
smell. The inhalation of its vapor, produces insensi-
bility to pain, and is much employed in surgical ope-
rations, for this purpose. Ether has the same effect,
in a less degree. A mixture of the two, is more com-
monly employed in this country.
936. FUSEL OIL. — Fusel oil is a peculiar
What is fusel ,.,-.,, f .
oil? Mention kind of alcohol, of extremely nauseous
its properties. Q^ an(j pOjsonous properties, which ac-
companies ordinary alcohol in its production from
potatoes and grain. It may he separated by nitration
through charcoal. But this process of purification is
often neglected, and the fusel oil left to add its poison
to the deleterious effects of the alcohol itself. It is
this doubly poisonous alcohol which forms the basis
of numerous manufactured liquors, wines, and cordials.
Fusel oil is the hydrated oxide of amyl. This radical
contains ten atoms of carbon, to eleven of hydrogen.
It belongs to the series of alcohols mentioned in the
first chapter of organic chemistry.
ORGANIC ACIDS.
mat is said 937- ACETIC ACID.— Ordinary vinegar
of theproduc- js a dilute acetic acid. It cannot be con-
tion and prop-
erties of acetic centrated by evaporation, as the acid is
volatile, as well as the water which dilutes
it. To obtain the strong acid, recourse is had to the
salts of acetic acid, from which it is prepared by the
method used for nitric and muriatic acids. The pure
TANN1C ACID. 373
acid is a solid. It mixes with water at low tempera-
ture, in all proportions, and is commonly seen in its dis-
solved state. Its compounds with metallic oxides are
called acetates. The sugar of lead, so called, is an
acetate, formed by dissolving litharge in acetic acid.
938. TANNIC ACID. — Tannin, or tannic
e acid> exists in nut-galls and in the bark
properties of and leaves of many trees. It is the prin-
tannic acid ? . . .... . , .
ciple which imparts to them their astrin-
gent taste, and gives to the tan liquor the property of
converting hides into leather. When separated from
the other substances with which it is combined in
nature, it is a yellowish, gummy mass. It is soluble in
water, and possesses the property of precipitating glue
or gelatin, and many other metallic oxides.
939. WRITING INK. — Common writing
What is the .
coloring mat- ink is prepared from nut-galls and proto-
ter^of writing sulphate of iron> When first made, it is
principally a tannate of the protoxide of
iron, and forms a very pale solution. Before
it is fit for use, it must be exposed for a time
to the air, and thereby converted, partially, into
tannate of the peroxide. This is a bluish black
precipitate, and imparts to it the requisite color.
It is essential to the permanence of ink, that
the change should take place, in part, in the fibre of
the paper itself. Too long exposure should, therefore,
be avoided in the manufacture. The pale ink thus
produced, which blackens further in using, is much more
permanent than a thicker, darker ink, produced when
this caution is not observed.
374 ORGANIC CHEMISTRY.
940. Six parts of nut-galls to four of
Give the pro-
cess of its copperas, are found to be the best propor-
preparation. tiong for prO(}Ucing a permanent ink. The
galls are to be boiled with water, the decoction strained,
and mixed with copperas solution. Gum and cloves
are added, the former to keep the coloring matter of the
ink from settling, and the latter to prevent its moulding.
After a ripening of a month or more the liquid is
strained. The coloring matter of ink is immediately
produced in a solution of copperas, as a bulky precipi-
tate, by the addition of tincture of galls, and a little
nitric acid.
HYDROCYANIC ACID.
941. CYANOGEN. — Before proceeding
Mention the . .
composition with the description of hydrocyanic, or
Pmssic acid> the production of cyanogen,
which enters into its
composition, will be briefly consid-
ered. Cyanogen is a colorless gas,
with a peculiar odor, resembling
that of peach pits. It is nearly twice
as heavy as atmospheric air. It
burns with a beautiful purple flame.
Cyanogen is a compound radical,
posssessed of important analogies to
chlorine, and the other electro-neg-
ative elements. Its molecule contains one atom of ni-
trogen and two of carbon.
How is cyano- 942. PRODUCTION. — Cyanogen may be
gen prepared? expelled from the cyanide of mercury, by
CYANIDES. 375
the agency of heat. This metal retains cyanogen as
it does oxygen, but feebly. A method more commonly
employed is to produce and decompose the cyanide of
mercury at the same moment. This is effected by
mixing chloride of mercury, to furnish the metal, with
the double cyanide of iron and potassium, which fur-
nishes the cyanogen. The other elements unite to
form chlorides of iron and potassium, while the cyanide
of mercury is decomposed as fast as it is formed. The
double cyanide of iron and potassium, above referred to,
is the commercial yellow prussiate of potash. Two parts
of this salt are to be heated with one of bi-chloride of
mercury, in the above process. The prussiate cannot
be used alone for the production of cyanogen, on ac-
count of the firm retention of this radical by the
highly electro-positive metals which enter into the com-
position of the salt.
How isc a- ^^* CYANIDE OF POTASSIUM. — Cyanide
nide of potas- of potassium is a white substance, resem-
siumprepar- , .. ... ,
ed? Mention bling porcelain m appearance, and quite
soluble in water arid Alcohol. It is largely
employed in preparing solutions of the precious metals,
for galvanic gilding and silvering. It is produced on a
large scale, by fusing together carbonate of potash and
refuse animal matter. The latter furnishes the carbon
and nitrogen required for the production of cyangen,
while the carbonic acid and oxygen of the salt, are
principally evolved as oxide of carbon. The cyanide
of potassium is best extracted from this residue by alco-
hol, which leaves the other material undissolved.
ORGANIC CHEMISTRY.
376
How is yellow 944 P^ssiATE OF POTASH.— Cyanide
prussiate of of iron is always incidentally formed from
potash pre- .
pared? Men- the iron of the vessel in the above process.
tion its uses, jf Wftter ig added t() th
cyanides dissolve ; although the latter, when alone, is
entirely insoluble. From the solution, the double cy-
anide of potassium and iron, mentioned in a preceding
paragraph, is obtained, by evaporation, in splendid yel-
low crystals. It is known in commerce as yellow
prussiate of potash, and is largely used in the arts for
the production of prussian blue and cyanide of potas-
sium. Prussian blue is obtained by adding its solution
to a salt of the peroxide of iron. As any solution of
iron is readily peroxydized by the addition of a little
nitric acid, the yellow prussiate may be employed as a
test for this metal.
945. FERROCYANIDES. — The yellow
What is said 3
of ferrocya.no- prussiate of potash, produced as above de-
scribed, is not properly a double cyanide
of iron and potassium. There is reason to believe
that the cyanogen is more intimately combined with
the iron than such a name would imply. It seems to
have lost its ordinary properties, in the compound.
Neither the alkalies, or sulphide of ammonium, which
usually precipitate iron from its solutions, have any
power to precipitate it from this salt. The three mole-
cules of cyanogen, which enter into its composition,
seem to have hidden and absorbed it. They have
formed with it, indeed, a new compound radical, called
ferrocyanogen. The double salt above mentioned is
therefore more properly a ferrocyanide of potassium.
PRUSSIC ACID. 377
Ferrocyanogen, like all other compound radicals, con-
ducts itself, under ordinary circumstances, as an ele-
mentary substance.
WJiatisfcrri- 946. On tne removal of one atom of
cyanogen? potassium from two molecules of this salt,
a coalescence of the ferrocyanogen of the two mole-
cules seems to be the result, and a new compound radi-
cal is formed. This radical is called ferricyanogen.
It combines with the three remaining atoms of potas-
sium, to form ferricyanide of potassium.
Give the ro - ^^ ' PRUSSIC ACID. — Hydrocyanic acid
erties of prus- is made from cyanide of potassium, by the
its mode of same method employed for producing hy-
preparation. drochloric acid from common salt. The
ferrocyanide of potassium is more commonly employed
in the process. Prussic acid is intensely poisonous. A
drop or two of the concentrated liquid, placed upon the
tongue of a dog, produces immediate death. On ac-
count of its extremely dangerous properties, the prepa-
ration of the acid should never be attempted except
by a professional chemist. The odor of the acid is
somewhat similar to that of cyanogen, and may be fre-
quently detected in the vicinity of establishments where
galvanic gilding is conducted. Ferrocyanogen and fer-
ricyanogen, like simple cyanogen, have their hydrogen
acids and series of salts. The acid of the former is
bibasic, and that of the latter tribasic, as already shown
by the composition of their potassium compounds.
What is said ^48. OTHER ORGANIC ACIDS. — Tartaric
of citric, ma- acid, before mentioned, is found in the
lie, lactic, ox-
alic, and for- grape. The acid tartrate of potassa or
mie acids ? cream of tartar, which deposits in wine
378 ORGANIC CHEMISTRY.
casks, is one of its most important salts. Another has
been mentioned under the head of antimony. Oxalic
acid is found in wood sorrel and in certain lichens. It
is also prepared by the action of nitric acid on wood,
sugar, and starch. When these substances are burned
in the air, their carbon is converted into carbonic acid.
Oxalic acid contains half the proportional quantity of
oxygen, and may be regarded as the product of a less
perfect combustion by the oxygen of nitric acid. It is
a white crystalline solid and a most dangerous poison.
The effect of heat on oxalic acid, with its precise com-
position, is given in the section on carbonic oxide.
Citric acid is the acid of lemons, malic acid, that of
the apple, and formic acid that of the red ant. The
latter may also be formed from wood spirit, by oxida-
tion, through the agency of platinum black, as acetic
acid is formed from ordinary spirit or alcohol. Lactic
acid will be again mentioned under the head of animal
chemistry.
949. THEIR COMPOSITION. — All of these
What is the
composition of acids differ in taste and in various chem-
*acids?Ve *ca^ Pr°Perties? as do those of inorganic
chemistry. Yet all of them contain the
same three elements which are also contained in wood,
gum, and starch. They contain these elements in
various proportion, but their peculiarities are not to be
ascribed to this cause alone. They may be regarded
as in part, at least, the consequence of a difference of
arrangement of the atoms, as has already been ex-
plained
ESSENTIAL OILS. 379
ESSENTIAL OILS.
What is said ^50. V°LATILE, OR ESSENTIAL OILS. •
of the compa- Oils of turpentine and lemon, and otto of
rative compo-
sition of es- roses, are examples of essential oils. They
sential oils ? are aimost as various as plants themselves.
Yet the composition of those that differ most widely
is often the same. This is the case with the oils of
orange, lemon, pepper, turpentine, juniper, parsley,
citron and bergamot. They contain carbon and hy-
drogen alone, and in the same proportion; twenty
atoms of the former to eight of the latter. Those of
bitter almonds, cinnamon, cloves, and anise-seed, con-
tain oxygen beside. Those of mustard, and onions,
contain oxygen, and sulphur, in addition, and are char-
acterized, like all sulphuretted oils, by a peculiar, pun-
gent smell, and acrid, burning taste.
951. OCCURRENCE AND PREPARATION. —
How are the .
essential oils Essentials oils are oftenest found in the
prepared? flowers, seeds, and fruits of plants, but
sometimes in the stalks and roots. From these they
are obtained by distillation with water. The volatile
oil passes over with the steam, and floats upon the con-
densed liquid in the receiver. Oil of turpentine is thus
made, from the common turpentine, or pitch as it is
sometimes called, which exudes from the pine ; ordi-
nary rosin remains behind. The delicate perfume of
violets, and other flowers which contain but a small
portion of essential oil, is extracted by mingling the
flowers with lard. This substance has the property of
absorbing the oil, and yielding it again by distillation.
co
380 ORGANIC CHEMISTRY.
952. USE OF THE ESSENTIAL OILS. -
What are the . .
uses of the es- 1 he essential oils are extensively em-
senttal oils ? ployed in the manufacture of essences, per-
fumes, and cordials. All of these liquids are solutions
of the oils in alcohol, with the addition, in the case of
cordials, of a portion of sugar. The oil of turpentine
is used in the manufacture of varnishes and burning
fluid, to be hereafter described.
953. BURNING FLUID. — " Burning fluid,"
What is the
position of so called, is a solution of camphene or
rectified turpentine in alcohol. The sole
object of the camphene is to increase the
proportion of carbon, and thus render the flame more
luminous. Unmixed camphene may also be burned in
lamps provided with tall chimneys. The effect of the
chimney is to make a strong draft, and thus provide a
liberal supply of oxygen in proportion to the large
amount of carbon which the liquid contains. With-
out this provision, camphene burns like camphor, with
much smoke, depositing a large part of its carbon in
the form of soot or lamp-black.
What is said 954 BURNING FLUID, "EXPLOSIVE."—
of the expio- The mixture of alcohol and camphene,
sibility of ./,.-,• i
" burning- known as burning fluid, is commonly
spoken of as explosive. That this is not
the fact, may be readily shown by pouring a little in a
saucer, and inflaming it. It burns, under these
circumstances, as quietly as from the wick of a
lamp. But if a can, containing burning fluid, be
shaken up and then emptied of its liquid con-
tents, it is found to contain an explosive atmos-
phere. To prove this, it may be tightly corked
BURNING FLUID. 381
and fired through a small hole punched in the side. On
applying a lighted taper to the opening, the can explodes
with a loud report, and is torn to pieces by the force
of the escaping gases. The small proportion of fluid
remaining in the can, after every drop that can be
poured out is removed, is sufficient to produce this
effect.
955. EXPLANATION. — The principle of
What is the
cause of the the explosion is precisely the same as that
explosion? involved in the same experiment with hy-
drogen and air. The only variation consists in the sub-
stitution of the combustible vapor of alcohol and cam-
phene, for hydrogen gas. It is the mixture of alcohol
vapor, and air, to which the effect is to be principally
ascribed ; the experiment may be made, indeed, as
well with unmixed alcohol, or ether, as with burning-
fluid. It may also be made with camphene, but in this
case the vessel must be warmed, in order to vaporize
the liquid in sufficient quantity.
956. The above experiment may be
Describe an- /. j •.-, c , • i -u
other form of performed with safety, in an open vial, by
the expert- vaporizing a drop or two of either of the
above liquids within it, and then apply-
ing a lighted taper to the mouth. In this case, the ap-
pearance of flame at the mouth of the vial, and a
rushing noise, is all that is observed. This experiment
will enable the student to disprove the alleged unex-
plosive character of certain fluids in use for purposes
of illumination. In moderately warm weather it is
sufficient to fill the vial, and then to empty it, in order
to form the explosive atmosphere.
382 ORGANIC CHEMISTRY.
957. ARTIFICIAL ESSENCES. — Many of
What «* naid
of artificial the essentials oils are compounds of organic
acids and bases. Several of them may be
artificially produced. Pine apple oil is a compound
butyric acid with ether or oxide of ethyl. The bu-
tyric acid of the compound may be prepared from
rancid butter or by fermenting sugar with putrid
cheese. Bergamit pear oil is an alcoholic solution of
acetates of the oxide of ethyl, with acetate of oxide
of amyl. The latter is the ether of the nauseous and
poisonous fusel oil, which has before been mentioned.
What is arti- 958. Apple oil is a compound of vale-
fdal apple rianic acid with the same ether. The
oil? Artifi-
cial oil of bit- valenanic acid of the compound is also
ter almonds? ^^ from fugel Q^ Oil of grapes, and
oil of cognac, used to impart the flavor of French
brandy to common alcohol, come from the same source.
Oil of winter-green may be prepared from willow bark
and wood vinegar. Oil of bitter almonds is prepared
from coal tar. These artifical essences, although pro-
duced in several cases from poisonous substances, may
be used as flavors with perfect safety. It is highly
probable and in many cases certain, that the flavor of
the fruits themselves, is owing to the presence of these
precise compounds, in small quantities.
,jr, , 959. EMPYREUMATIC OILS. — The vola-
What are em-
pyreumatic tile oils which are produced by the de-
structive distillation of vegetable and ani-
mal substances receive this general name. The oils
of wood and coal tar are examples. Another em-
pyreumatic oil is produced in the combustion of to-
RESINS. 383
bacco in ordinary pipes. This oil is extremely poison-
ous. It is to be understood that these oils do not exist
ready formed in the substances from which they are
obtained, but are produced in the re-arrangement of
atoms, which takes place when organic bodies are sub-
jected to a high temperature.
960. CAMPHORS. — Several of the oxy-
What is the . J
origin of the genated essential oils deposit white crystal-
wnphonf line solids by cold These are frequently
isomeric with the oils themselves, and are called cam-
phors. Ordinary gum camphor is obtained like the es-
sential oils, by the distillation of the leaves of the Lau-
rus Camphor i with water. Its volatile character is the
occasion of a singular appearance, when small bits of
the substance are thrown upon warm water. The par-
ticles are seen to sail about as if they were possessed
of life, owing to the propelling effect of the vapor
which escapes beneath them. ,/A—
How are re- 961. RESINS. — The resins, of which
sins formed? ordinary pine rosin may serve as an exam-
ple, are formed by the action of oxygen upon the essen-
tial oils. Oil of turpentine may be thus partially con-
verted into resin, by long exposure to the air. On sub-
sequently heating it, only a portion is found to be vola-
tile, while a resinous mass remains behind. Turpen-
tine, or pitch of pine trees, is thus formed in nature,
from the oil of turpentine, as it exudes from the
trees. But the conversion is only partial, so that the
turpentine yields, on distillation, a portion of oil, while
rosin remains behind. Resins are easily distinguished
from gums by their insolubility in water ; they are, on
384 ORGANIC CHEMISTRY.
the other hand, readily soluble in alcohol or ether.
They are not liable to decay, like most other substan-
ces of vegetable origin. Copal, shellac, mastic, and
amber, are all resins. The latter is found in certain
coal mines, and at the bottom of the sea, and has
probably had its origin in the forests of some primeval
age.
962. EXPLANATION. — The action of
Explain the ~ , ... ,
above trans- the oxygen of the air, m the above case,
formation? ^ similar to that which occurs in the con-
version of alcohol into vinegar. A portion of the hy-
drogen is burned out, as it were, and removed in the
form of water, while another portion of oxygen takes
its place.
963. USE OF THE RESIN VARNISHES.
what use is
made of the The resins are principally employed for the
TarT varnishes production of varnishes. These are simply
made? solutions of resins in alcohol, ether, or
spirits of turpentine ; or an intimate mixture of the
latter with fused resin and oil. In preparing copal var-
nish, which is the most brilliant and durable, the resin
is first fused, then incorporated with heated oil, and
afterward diluted with spirits of turpentine. A com-
mon varnish for maps, engravings, and similar objects,
is made by dissolving mastic with a little Venice tur-
pentine and camphor, in spirits of turpentine. Pounded
glass is added to the pulverized material during the
process of solution. The object is covered with a so-
lution of isinglass before using this varnish, to prevent
its absorption. Shellac, in alcohol, is employed to
impart to wood or other material a resinous coating^
RESINS. 385
which is afterward polished with rotten stone. Copal
varnish is also similarly used. Shellac, dissolved in
soda or potash, is sometimes used to give body to
paints, as a substitute for part of the more expensive
material.
What i« rosin 964. ROSIN SOAP. — The resins possess
soap? an acid character, and like fats, form soap
with the alkalies. Common rosin is largely consumed,
with fat and potash, in the manufacture of common
brown soap. The greater hardness which it imparts
depends on the formation of a certain portion of rosin
soap, in the mixture.
965. SIZING. — The soap which is
How is rosin
used in sizing formed on boiling rosin with strong potash
paper? -g uge(j m sjznig paper. Being mixed with
the material from which paper is to be made, a solution
of alum is afterward added to the pulp, and a compound
of rosin and alumina thus produced in every portion of
the mass. The pores of paper made from this mate-
rial are thus completely filled, and the spreading of
the ink prevented. A surface sizing which is less ef-
fectual, is also given to paper by a solution of glue,
applied after the paper is formed. When this is de-
stroyed by erasure, its place may be supplied, and the
spreading of ink prevented, by rubbing powdered rosin
upon the spot from which the sizing has been removed.
966. SEALING-WAX. — Sealing-wax con-
What is the
tionof sists, principally, of shellac. Venice tur-
pentine is added to make it more inflam-
mable and fusible, and vermilion or lamp-black to color
it. Ship pitch is resin changed and partially decom-
17
cotnposi
sealing-icax ?
386 ORGANIC CHEMISTRY.
posed by heat. Shoemakers wax is made by a similar
process.
What are the ^67. ROSIN OIL AND GAS. Rosin is
products of partially converted by dry distilla-
te dry distil- \ . . . , .
lation of tion into an oil, which is largely
used for adulterating other oils, and
also for purposes of illumination. A black pitch
remains in the retort. The oil has the advan-
tage of extreme cheapness, but owing to its
large proportion of carbon, can only be burned
in lamps furnished with tall chimneys. At a
still higher temperature rosin is converted into
gas, with a residue of carbon.
What is as- 968. AspHALTUM. — Asphaltuni or bi-
phaltum? tumen is a mineral resin, similar to the
black pitch which remains from the distillation of coal
tar. This material is found on the shores of the Dead
Sea, in the island of Trinidad, and in several European
localities. It is extensively employed for hydraulic
cements, roofing, and pavements.
969. PETROLEUM. — Petroleum is a liquid
What is said .
of the source, hydrocarbon, also known as rock oil. It is
often found uPon standing water, in bitu-
ofpetrole- minous coal districts. Pits are also dug
for the purpose of collecting it. These
become filled with water, upon which the oil rises, more
or less abundantly. The rectified petroleum is called
naptha, and is a nearly colorless and highly volatile
fluid. The entire absence of oxygen in its composi-
tion, adapts it perfectly to the preservation of the metals
potassium, and sodium, in their metallic condition.
CAOUTCHOUC. 387
It is also used as a solvent of sulphur, phosphorus, fats,
resins, and caoutchouc. Both asphaltum and petroleum
have been, probably, produced by the action of vol-
canic fires upon bituminous coal.
970. GUM RESINS. — The dried juices
what is said . ,
of gum re- of certain plants consist of mixtures of
gum and resin. These mixtures are called
gum resins. Water dissolves the gum, and holds the
resin in suspension, thus forming what is called an
emulsion. Alcohol, on the other hand extracts the re-
sin from their mixtures. Assafoetida, gamboge, and
opium, are a few examples of gum resins.
971. CAOUTCHOUC. GUM ELASTIC. —
Mention the • i i ' « •
sources and Caoutchouc is a hydrocarbon, obtained from
™outchouc°{ tne milky Juice °f certain trees in Asia,
Africa, and South America. This constit-
uent of the juice hardens, on exposure to the air, while
the remainder is removed by evaporation. By the ad-
dition of a little ammonia, the milk may be retained in
its liquid condition. Caoutchouc is soluble in ether,
spirits of turpentine, oil of coal tar, and many other
hydrocarbons. Sulphuret of carbon, a volatile liquid
obtained by passing sulphur vapors over ignited char-
coal, is also a complete solvent of India-rubber and
gutta percha.
972. VULCANIZED RUBBER. — Heated for
How is caout-
chouc vulcani- a snort time with sulphur, at 280°, or
Zave the^rl - somewnat above this point, caoutchouc
ertiesof mil- becomes remarkably changed in its nature,
canized " rub- -, • . ~ , . , , ,,
ber?» and is no longer stiffened by cold, or soft-
ened by heat. It is then called vulcanized
388 ORGANIC CHEMISTRY.
rubber, and constitutes the material out - of which
most India-rubber goods are now made. The hard
rubber which is extensively employed for the manu-
facture of cornbs, knife-handles, pencil-cases, &c., is
composed of pitch, India-rubber, sulphur, and mag-
nesia. The mixture is softened at about 270°, then
pressed into moulds to give it the required shape. It
is afterward wrought like ivory.
Whatisgutta 973' GUTTA PERCHA.— Gutta percha is
percha? identical in composition with gum elastic,
Mention some , , _.„
of its proper- but possessed of quite different properties.
ties and uses, ^mong them is its extreme toughness, and
comparatively slight elasticity. It is rendered soft and
plastic by immersion in boiling water, and in this pasty
condition may be moulded into any required shape. It
can be vulcanized, like caoutchouc, and is then proof
against elevation of temperature. It is employed as a
substitute for caoutchouc where great elasticity is not
required. Both of the above substances approach more
nearly in their composition to the essential oils, than to
any other class of compounds.
PROTEIN BODIES— PUTREFACTION".
Stated com- 974' VEGETABLE FIBRIN.— The glutin-
position and ous mass which remains when dough is
properties of . .
vegetable kneaded in water until all the starch is
fibnn. removed, is called gluten or vegetable
fibrin. It diners from all the organic matter hitherto
described, in containing nitrogen, with small quantities
VEGETABLE ALBUMEN. 389
of sulphur, and phosphorus. Its exact composition is
given in the Appendix. It is a grey substance, and is
the material which gives its cohesion to bread.
975. VEGETABLE ALBUMEN AND CASEIN. —
What is said . • -i r.
of vegetable Vegetable albumen is a similar substance,
contained, ni smaller quantity, in the juices
of fruits and vegetables. It is coagulated
by heat, like the white of egg, when the juices are
boiled. Vegetable casein is another substance of very
similar composition and properties, found principally
in the seeds of leguminous plants. It precipitates like
the curd in sour milk, when a little acid is added to
an aqueous extract of the seeds. These substances
derive their names from their resemblance to animal
fibrin, albumen, and casein. Vegetable casein is also
called legumine. All of these substances were at one
time supposed to be compounds of a single substance,
called protein, itself free from both sulphur and phos-
phorus. Later experimenters have not succeeded in
isolating such a substance, and the theory is therefore
abandoned. The name is retained in this work as a
convenient designation of the class of substances here
considered.
976. OCCURRENCE. — One or more of
Where are the
above subxtan- these substances is present in greater or
cesfuund? legs quantity in au parts of piants. They
are found accumulated with starch, in the fruit and
seed. The seeds of cereals, such as wheat and rye,
and those of leguminous plants, such as peas and beans,
contain them in large proportion.
390 ORGANIC CHEMISTRY.
,r , 977. CHARACTERISTICS. — If a bit of
Mention a pe-
culiarity of gluten be placed on the end of a wire and
burned, a very different odor is produced
pounds. from that of burning starch or wood.
The smell approaches that of burning wool, and is a
means of distinguishing organic matter which contains
nitrogen. If boiled with potassa, the sulphur of gluten
is extracted, and the solution will blacken paper moist-
ened with sugar of lead. This reaction furnishes an-
other means of detecting nitrogenous substances.
978. PUTREFACTION. — A still more im-
Describethe . *.'••. i_
process of pu- portant distinction of nitrogenous substan-
trefaction. ceg from those which contain no nitrogen,
is their spontaneous putrefaction. Left to themselves,
they are resolved, like blood and flesh to which they
are allied in composition, into a variety of other pro-
ducts. It is not strictly correct to say that this decom-
position is spontaneous. The substance must first
have been exposed to the air. An oxidation or slow
combustion is then commenced, which, although en-
tirely imperceptible in its effects, and checked at once
by exclusion of air, ensures the subsequent putrefac-
tion. It burns out a small portion of carbon and hy-
drogen, and thus removes, as it were, the key-stone of
the arch in every molecule. The atoms may then be
supposed to fall together and re-arrange themselves as
is required by the known products of their decompo-
sition.
979. PRODUCTS OF PUTREFACTION. — The
Mention some ^. 'L-%> ' r
products of re-arrangement which occurs m putrefac-
ef action. consistSj essentially, in the combustion
FERMENTATION. 391
of the carbon of the substance with oxygen, while the
hydrogen divides itself between the nitrogen, phospho-
rus, and sulphur, forming ammonia, phosphuretted and
sulphuretted hydrogen. It is to these gases that the
offensive smell which is given off in putrefaction is
principally to be ascribed.
980. FERMENTATION. — Any one of the
What substan- . ,
ce* are capable nitrogenous substances above mentioned,
of producing hij undergoing the change which is
jermentation ? D
called putrefaction, is capable, by its mere
presence, of acting as a ferment. A little putrefying
gluten, for example, added to a solution of sugar, will
convert it into alcohol and carbonic acid. Here again
the key-stone of the molecule is removed, or rather in
this case moved. The motion of the atoms of the
putrefying substance would seem to be the cause.
The effect is analogous to that of heat, through whose
agency, also, complex organic bodies are resolved into
others of simpler constitution.
981. YEAST. — The first stage in the
What is the
first stage in formation of yeast is the production of a
the process? microscopic vegetation, which consumes
all the protein, converting it in.to the substance of a
microscopic plant. Ordinary brewers' yeast is such a mi-
croscopic vegetation. Being produced, it passes imme-
diately into the putrefaction above described, effecting,
at the same time, the conversion of any sugar which
may be present into alcohol and carbonic acid. By
some, the growth of the microscopic plant itself, instead
of its subsequent change, is supposed to be the cause
of fermentation.
392 ORGANIC CHEMISTRY.
Holds yeast 982. PRODUCTION OF YEAST. - Yeast has
produced? not onjy fae pOwer of converting sugar
into alcohol, but it at the same time occasions the
production of more yeast from dissolved protein. In
the ordinary process of beer brewing, the newly formed
yeast collects on the surface of the fermenting vats.
It is thence removed, to serve as the excitant of a new
fermentation, or to be employed in the production of
bread, which is, chemically considered, an analogous
process.
983. DIFFERENT KINDS OF FERMENTA-
Mention seve-
ral kinds of TioN. — The products of fermentation are
fermentation. Different, according to temperature and
other circumstances. Thus the same sugar which at
40°, to 86°, with cheese used as a ferment, yields car-
bonic acid and alcohol, at a temperature of 86°, to 95°
is converted into lactic acid. The latter, by the further
action of the curd, with slight elevation of tempera-
ture, is converted into butyric and carbonic acids. By
the same ferment, at a still higher temperature, a portion
of gum is produced with the lactic acid. These diffe-
rent processes of transformation have received, respec-
tively, the names of the vinous, lactic, butyric, and
viscous fermentations. The conversion of starch into
sugar by diastase may be regarded as a species of fer-
mentation. This substance is a slightly changed glu-
ten. It is always produced in germination, and may
be precipitated by alcohol in the form of white flakes,
from a concentrated infusion of malt. One part of it
is sufficient to convert two thousand parts of starch
into sugar.
BREAD. 393
What is said 984 FLOUR.— Fine flour makes less
of the nutri- nutritious bread than the coarser varieties.
tious proper- .!*•*>*
ties of fine because it contains a smaller proportion of
gluten. Gluten being tougher than the
starch, is not reduced to so fine a powder, and is par-
tially separated in the process of bolting. All grains
contain sugar in small proportion. Sugar is therefore
one of the constituents of flour.
Whatchemi- ^85. BREAD. — The " raising" of bread
cat principles is a process of fermentation. The yeast
are involved
in making employed in the process converts a portion
of the starch of the flour into sugar, and
subsequently into alcohol and carbonic acid. The
sponge is made light and porous, by the gas bubbles
which become entangled within it. A large part of
the alcohol produced in the process escapes into the
oven, and thence into the exterior air. It may be
condensed and converted into spirits by the proper
apparatus. This has been successfully done in large
bakeries in Europe, but the process has not been found
to be of any considerable economical importance. In
the process of baking a portion of starch is converted
into gum. By moistening the baked loaf with water
the gum is dissolved, and by a new heating, hardens
into the shining surface which is often observed on
bakers' bread.
What materi- 986- YEAST POWDERS.— The gas which
ais are some- is needed to make bread lia:ht, may be
times substi-
tuted for produced by other means than the process
yeast / of fermentation. If carbonate of soda, for
example, is kneaded into the dough, and tartaric acid
17*
394 ORGANIC CHEMISTRY.
subsequently added in proper proportion, the weaker
carbonic acid is expelled. A light sponge is produced
by its escape, without the loss of the starch and sugar
which are consumed in the process of fermentation.
Soda and tartaric acid prepared for this purpose are
known under the name of yeast powders. Carbonate
of ammonia being entirely volatile by heat, may be
employed alone for the same purpose. A portion of
the salt probably remains in the bread, and is more or
less injurious, on account of its alkaline character.
987. TEST FOR YEAST POWDERS. — The
What is the . . f ,
objection to great objection to the use of these pow-
*faUinlfreadf ^GYS *u the PreParation °f bread, consists
in their liability to contain soda or acid in
undue proportion. Whether this is the case, may be
ascertained by dissolving the powders in water, and
mixing the solutions. If the product is neutral to the
taste and does not effervesce on the addition of
either soda or acid, this fact will be evidence of their
proper preparation. If otherwise, more or less injury
is to be anticipated from their use. Excess of the al-
kalies especially interferes with the process of diges-
tion, by neutralizing the acids which accomplish it.
The use of soda and saleratus with sour milk is liable
to the same objections.
What is said, ^88. THEIR EFFECT ON HEALTH. It
Ihe^rfffe^'on ma^ wel1 be <lliestioned whether bread
the health ? prepared by this process, is ever as healthy
as that made with yeast. For even the neutral tar-
trate, formed when the materials are used in proper pro-
portion, will tend to neutralize certain stronger acids,
ALKALOIDS. 395
which are constituents of the gastric juice. It may
thus interfere, in a measure, with the process of diges-
tion. If pure muriatic acid were substituted for the
tartaric acid or cream of tartar, this objection would be
removed. The product of its action on soda is com-
mon salt.
ORGANIC BASES.
989. ALKALOIDS. — Morphine and strych-
namesofsome nine, the former a useful medicine, and
fold™ alWh the latter> tlie most dreadful of poisons, are
are they so examples of the alkaloids. They are
white crystalline bodies, but slightly solu-
ble in water. Most of them, like the protein bodies
above mentioned, contain the four organic elements ;
but they differ widely from these substances, in possess-
ing a positive chemical character. They are called
alkaloids from their resemblance, in certain properties,
to the alkalies of inorganic chemistry. Their action
upon vegetable colors is the same ; like the alkalies,
they also form salts with both organic and inorganic
acids. They are, in fact, true alkalies. Their alkaline
property does not, however, seem to depend on the
oxygen which they contain. Some of them, indeed,
do riot contain this element. It is highly probable that
certain of the alkaloids belong to the class of compound
ammonias mentioned in the first chapter of Organic
Chemistry.
What is their 990. Their action on the human body
action on the does not depend upon their alkaline char-
human body ?
Thdr anti- acter, but on other and peculiar properties
***' belonging to each. The salts of the alka-
396 ORGANIC CHEMISTRY.
loids are generally preferred in medicine, in view of
their ready solubility. In large doses they are all
poisonous. The tincture of nut-galls is employed as
an antidote, because of the property of the tannic acid
which it contains, to form with most of the alkaloids
insoluble precipitates.
991. OCCURRENCE. — Morphine is con-
Wfiat is the . r
source of the tamed in opium, qmmne is extracted from
alkaloids ? Peruvian bark, and strychnine, from the nux
vomica. The latter is also the poison of the celebrated
upas. Theine and nicotine are other alkaloids, the
former of which is found in tea and coffee, and the latter
in tobacco. Theine may be obtained, as a sublimate
of silky crystals, by moderately heating tea in an iron
pot covered with a paper cone.
992. PREPARATION. — Most of the alka-
How are the
alkaloids ex- loids may be extracted from the material
which contains them by means of acidu-
lated water. A salt of the alkaloid is thus obtained in
solution. From this salt the alkaloid may be precipi-
tated, like oxide of iron or any other base, by. am-
monia. Nicotine is a most energetic poison, falling
scarcely below prussic acid in its destructive properties.
COLORING MATTERS.
What is said 993. INDIGO. — The vegetable dye-stuffs
of indigo? are extremely numerous. Indigo, madder,
and logwood are among the more important. Indigo
is deposited from the colorless juice of certain plants
by simple exposure to the air. It may be sublimed in
DYEING. 397
purple crystals, by rapid heating. By removing the
oxygen absorbed in its production, the original color-
less juice may be, as it were, reproduced from commer-
cial indigo. This object is effected by the use of pro-
tosulphate of iron, which is converted into sulphate of
the peroxide in the process. Caustic lime is at the
same time added to dissolve the deoxidized indigo.
The colorless solution is employed in dyeing ; cloth im-
pregnated with it becomes blue on exposure to the
air. A solution of indigo in concentrated sulphuric
acid is also employed in dyeing.
Wh,at is mad- 994. MADDER. — Madder is the ground
der? root Of t^ rulia tinctoriutn. This plant
is cultivated extensively in India and Europe. It con-
tains a red dye, produced by the action of the 'air or
certain chemical agents, upon the juices of the recent
plant. This body is called alizarine, and may be ob-
tained in beautiful crystals. An infusion of the root in
hot water contains a portion of this substance in solution.
What is log- 995. LOGWOOD. — This is a red wood,
wood? obtained from Spanish America and much
employed in dyeing. Its coloring matter is called he-
matoxyline. By evaporating a decoction of the wood
and re-dissolving in alcohol, this substance may be ob-
tained, on a second evaporation, in the form of yellow
crystals.
DYEING.
996. DYEING. — Few dves can be per-
Explain the *
theory of dye- manently imparted to cloth without the in-
ing fast colors. tervention Qf some third substance, which
398 ORGANIC CHEMISTRY.
shall, as it were, hold them together. Such a substance,
with strong affinity for the coloring matter of the dye,
and also for the fibre of the cloth, is called a mor-
dant. The fabric to be dyed being first impregnated
with the mordant, is then introduced into the dyer's
vat to receive its permanent color.
What is said 997. MORDANTS.— Alumina and oxide of
of mordants? jron are fae principai mordants employed.
They may be " fixed " in the cloth by immersion in the
acetates of these oxides. A subsequent exposure for
several days to the air is essential, in order that the
acetic acid may in part be expelled. A portion of it,
however, remains, so that the oxides are, strictly speak-
ing, in the condition of basic acetates. After this ex-
posure, and subsequent washing in hot water, the fabric
may be immersed in the dye. An ounce of madder
heated with a pint of water will be sufficient for an
experiment. The fabric is to be boiled for an hour or
more with the unstrained decoction.
998. PREPARATION OF THE MORDANT. —
How is the alu- .
minous mor- The solution of acetate of alumina is
most conveniently prepared from alum, by
the substitution of acetic for its sulphuric
acid. This is accomplished by the addition of acetate
of lead. Sulphate of lead is at the same time precipi-
tated, and may be filtered off from the acetate which is
formed. Three pounds of alum and two of sugar of
lead, to three gallons of water, are the proportions to
be employed. This mordant produces a red color.
How are vari- 999. VARIOUS COLORS BY THE SAME
ous colors pro- DYE — gy faQ use of different mordants.
ducedfrom one
dye? various colors may be produced from the
MINERAL DYES. 399
same dye. Substitute four pounds of green vitriol for
the alum used in. the previous case, and the madder
gives a deep black. Add four ounces of arsenic with
the green vitriol, and a mordant is produced with which
the dye will yield a beautiful purple. In the latter
case, the solution must be reduced to one-tenth of its
original strength by the addition of water.
1000. DYEING WITH LOGWOOD. — By the
briefly the pro- employment of the last two mordants,
with °lo dwood9? mixed m equal proportions and diluted with
an equal quantity of water, a mordant for
dyeing black with logwood is obtained. For dyeing
purple with the same material, a tin mordant is used.
It may be prepared by dissolving tin in muriatic acid,
with the gradual addition of nitric acid, then precipi-
tating and re-dissolving with potassa. The cloth being
impregnated with this mordant and thoroughly dried,
is passed through dilute sulphuric acid, to remove the
potassa and leave the oxide of tin. After subsequent
drying and exposure to the air, the fabric is ready for
the dye.
What are 1001. MINERAL DYES. The dyes de-
minerai dyes? scriDed in the following paragraphs, are
distinguished from those before mentioned, by contain-
ing no organic matter. They consist of colored salts or
oxides, precipitated in the fibre of the cloth. Although
these substances belong, strictly speaking, to inorganic
chemistry, they are here introduced to complete the
survey of the subject of dyeing and calico printing.
1002. PRUSSIAN BLUE. — A mineral blue
How is a min-
eral blue ob- may be produced by impregnating cloth
tamed? ^^ ^ soiution of acetate of iron, before
400 ORGANIC CHEMISTRY.
described as a mordant, and then immersing it in an
acidified solution of prussiate of potash. Prussian blue
is thus precipitated in the cloth. This blue is found to
be brightened by passing it through a solution of sugar
of lead.
1003. MINERAL GREEN. — A mineral green
How is a min- .*-..,
eraigreenpro- is produced in the same manner by the em-
duced? ployment of sesquichloride of chromium,
and subsequent immersion in potassa. The color con-
sists of sesquioxide of chromium, precipitated from the
chromium salt by the action of the alkali. The so-
lution of sesquioxide of chromium is prepared by the
addition of sugar to a solution of bichromate of potassa
in dilute sulphuric acid. A part of the oxygen of the
chromic acid being abstracted by the organic matter, it
is converted into an oxide, which remains in solution.
1004. CHROME YELLOW. — To produce a
How is a min- . .
eral yellow mineral yellow, the cloth may be impreg-
produced? nated with acetate or nitrate of lead, then
dried and passed through sulphate of soda, to fix the
lead as sulphate in the cloth. On finally immersing
it in bichromate of potassa, the cloth becomes dyed
with yellow chromate of lead. The above process
modified by printing instead of saturating with acetate
of lead, gives yellow figures on a white ground.
CALICO PRINTING.
How is a white 1005. WHITE FIGURES. — If it is desired
^oods °rodyed t0 obtain a design in white, on goods dyed
duced? with either of the above madder colors,
CALICO PRINTING. 401
HXY
the design is printed with a
paste of tartaric acid upon the
colored cloth. On subsequently
immersing the goods in a bath
of chloride of lime, chlorine is evolved in the tissue,
and the color discharged only where the acid is printed.
The white thus produced is of course in exact cor-
respondence with the printed design.
Howareyellow 1006- PANTED YELLOW AND BLUE.— To
and blue de- produce yellows on madder red and purple
signs obtained '
on dyed grounds, before described, tartaric acid is
grounds t printed with the nitrate of lead, and the
cloth immersed in bleaching liquid. The color of the
printed portions is discharged by the combined action
of the acid and bleaching liquor ; the lead is at the
same time fixed in the cloth, as chloride of lead. On
subsequent immersion in bichromate of potassa, the
yellow figures of ehromate of lead are produced as be-
fore. For blues on the same colored grounds, a mix-
ture of Prussian blue, dissolved in bichloride of tin,
with tartaric acid, is printed on the cloth. The dis-
charge of the ground color beneath the figure, is
effected, as before, by chloride of lime.
1007. VARIEGATED PATTERNS. — All of
How are varie- •.•«_•
gated patterns the madder colors which have been men-
produccd ? tioned, may be produced upon a single piece
of white goods, by printing the different figures of the
pattern with different mordants. This is accomplished
by passing the fabric between different sets of rollers,
each of which is supplied with a paste of the proper
mordant, and so engraved that it yields the desired im-
402 ORGANIC CHEMISTRY.
pression. On subsequently introducing the goods into
the madder bath, the various colors are developed. The
whole piece is at the same time transiently colored ;
but the dye may be readily removed from the imprinted
portion by thorough washing. A white ground for the
colors is thus obtained.
RELATION OF PLANTS TO THE SOIL.
AGRICULTURAL CHEMISTRY.
1008. The mineral substances which
What mineral , , _, . ,. . ., , ,
substances do plants obtain from the soil, are known by
plants obtain anaiysis of the ashes which they yield on
from the soil ? J J
combustion. They consist of acids and
bases, which enter into the composition of all fertile
soils. The bases are potassa, lime, magnesia, and
oxides of manganese and iron. These are found com-
bined in the ashes with silicic, sulphuric and phosphoric
acids, and are accompanied by small proportions of
common salt. The carbonic acid which is found in
certain ashes is produced in the combustion of the
plant. The ashes of all cultivated plants contain the
above substances ; but in different proportions accord-
ing to the nature of the plant. The phosphates pre-
dominate in grains ; lime exists in large proportion in
grasses ; potash in edible roots ; and silica in straw. The
approximate composition of the ash of different plants
is given in a table in the Appendix. In estimating the
relative proportions of the different constituents which
are abstracted from the soil by different crops, the quan-
tity of the crop, as well as the composition of its ash,
is of course to be brought into this account.
CONSTITUENTS OF SOILS. 403
1009. COMPOSITION OF SOILS. — Many of
Of what are J
soils com- the above substances are contained in the
pose ' soil in extremely small proportion. Soils
are principally composed of vegetable matter in a state
of decay, with clay, sand, and carbonate of lime. The
vegetable matter consists of the remains of plants of
previous years, and the clay, lime, and sand, are the
product of the gradual crumbling and decomposition
of rocky crust of the earth.
1010. USE OF VEGETABLE MATTER IN
State the uses
of vegetable SOILS. — The wood, leaves, and twigs of
™oihT m which vegetable matter is composed, fur-
nish, in their gradual decay, the potash,
silica, and other constituents of their own skeletons to
form the framework of new plants. The organic mat-
ter is, at the same time, converted into ammonia and
carbonic acid ; these constitute the gaseous food on
which all vegetable life is sustained.
1011. ADDITION OF VEGETABLE AND ANI-
K$Zd -AL MATTER._The addition of more of
by the addi- this material to the soil, in the form of peat
tion of vegeta- - • /•
bh and animal or muck from swamps, is of great advan-
taSe? because it increases the supply of the
two important classes of materials which
have been mentioned. Animal matter of all kinds,
whether decomposed, as in stable manure and guano,
or in its original condition in the form of flesh, wool,
and bones, is a still more valuable addition to the soil.
The reason of its higher value, consists in the fact
that while it yields most of the other substances which
decaying vegetable matter supplies, it furnishes ammo-
404 ORGANIC CHEMISTRY.
nia, which is the rarest and most expensive one, in
much larger proportion.
1012. USE OF THE CLAY. — The clay in
What purpose .
does day sub- soils serves to retain the ammonia and
e certam otner valuable materials, which
would, otherwise, be washed away by
descending rains. It seizes not only upon that which
comes from the decaying humus, but finds particles in
the drops of every shower, which it stores safely away
for the future use of the plant. It serves also to retain
moisture in the soil, and to impart to it the tenacity
by which the roots are enabled to gain a firm hold upon
the earth. Soils which contain but a small proportion
of clay are for these reasons improved by its addition.
1013. USES OF THE SAND. — Sand, where
What is the
office of sand it exists in due proportion, gives the proper
tn wist degree of porosity to the soil, and thus
ensures the entrance of the air and fertilizing liquids,
and the draining away of all excess of water. Access
of air is important, because it brings with it fertilizing
ammonia and carbonic acid, and by accelerating the
decay of vegetable matter, produces more of these
valuable substances.
1014. USES OF THE LIME. — The lime in
What is the -, . , , -, -, •
office of lime soils, beside serving directly as building
on the soil? material for all forms of vegetation, is the
key which unlocks other treasures of the soil and sup-
plies them, also, to the growing plant. The building
material which is furnished, as before explained, by
the decay of previous plants, is not sufficient. A por-
tion of it never reaches the fields from which it was
ACTION OF LIME. 405
originally derived. Exported in the form of grain, or
milk, or beef, it returns to the soil in some distant re-
gion or is poured into the rivers and the sea through
the drains of populous cities. New supplies of potash
and other material, are, therefore, demanded by the
vegetation of every successive year.
1015. A large part of the materials re-
How docs it .
accomplish the ferred to are locked up in hard grains of
object ? granite, or other silicates which are found
in the soils. Being insoluble in water and the other
solvents of the soil, they are inaccessible to the plant.
Lime has the property of forcing itself into the rocky
prison of every such insoluble grain, and setting part
of its inmates at liberty. At the same time it opens
the door to the action of other agencies which liberate
the rest. They are then floated away in the water
which penetrates the soil, and being in due season ab-
sorbed, are built into the substance of the plant.
1016. ACTION OF LIME ON MINERAL MATTER
Give the chem- ......,, , ... .
ical explana- EXPLAINED. The actlOll of lime, Which
tfon US a°~ nas Just been mentioned, is a simple conse-
quence of its basic properties. It takes
possession of part of the silicic acid of the alkaline
silicate in the rocky grains. Their potassa and soda
being now combined with this acid in small proportion,
are soluble in the water which penetrates the soil.
10 17. The water of the soil always con-
What other . . •/--.•• j
decomposing tains a certain proportion 01 carbonic acid.
as%™st/xist'sin This acid being itself material for vege-
table nutrition, has also the property of
dissolving those mineral substances which the plant
--P •
406 ORGANIC CHEMISTRY.
needs for its support. By the joint action of carbonic
acid and water, this transfer is constantly going on
even without the aid of lime. But the latter substance
very much accelerates the action, arid thus adds greatly
to the fertility of the soil.
1018. ACTION OF LIME ON ORGANIC MAT-
Mention an- . .
other use of TER. — Lime has another important enect
lsoil°nihe on so^s' m hastening the decomposition
of their organic matter, and thus, indi-
rectly, supplying in large quantity, valuable materials,
before mentioned, which these are adapted to furnish.
As this decomposition proceeds in the presence of lime,
part of the nitrogen of the organic matter takes the form
of ammonia, and part is converted into nitrates, as will
be remembered from the chapter on Salts. But the
proportion of either is practically immaterial, as both
are found to subserve a similar purpose in building up
the plant.
1019. All of the effects which have
* been mentioned, may be regarded as grad-
tioned effects ually produced in every soil which contains
increased ?
Mention an- carbonate of lime as a constituent. When
° it; is deficient in quantity, they are, of
course, increased by its addition in the
form of chalk or marl, or limestone. These substances
have also the effect of sweetening peaty and marshy
soils, which are rendered sour from the presence of too
large a proportion of vegetable matter, and thus ren-
dering them fit for cultivation.
1020. BURNED LIME. — Burned or caustic
In what form
has lime the lime has all these effects in a much greater
degree, and therefore its extensive use as
a fertilizer of the soil. It should be used
GUANO. 407
cautiously on soils which contain but a small propor-
tion of vegetable matter, for fear that in the more rapid
decomposition which it stimulates, it may entirely
exhaust the soil of this material. If employed in such
cases it should be with admixture of vegetable matter,
that the loss which it occasions may be completely
replaced.
1021. EFFECT OF ASHES ON SOILS. —
What other _ . .
substances act Potassa or soda applied in the caustic state,
similarly? Qr ag carbonates have entirely analogous
What caution
is to be observ- effects on the soil. They render the in-
edin their use? , , , .'
soluble silicates soluble, by increasing in
them the proportion of base, and also hasten the decay
and conversion of vegetable matter. The admixture
of lime or ashes with guano or decomposed manure, is
to be avoided, because of their effect to expel the
ammonia which these substances contain. This may
be avoided by previously incorporating the material
with a large proportion of clay or vegetable mould,
which shall serve as an absorbent of the liberated
gas.
What is said 1022. COMPOSTS. CompOStS COllsist of
of composts? vegetable and other matter, heaped to-
gether for fermentation and partial decay, in order to
prepare them for application to the soil. In such mix-
tures, all alkaline materials, including lime, have an
effect similar to that which they produce upon the
organic matter of the soil.
Whatisgua- 1023. GUANO. — Guano consists of the
no? accumulated droppings of birds, and is
principally obtained from certain rocky islands on the
408 ORGANIC CHEMISTRY.
coast of South America. In these haunts of the heron
flamandj and other sea-fowl, it is accumulated, in some
instances, to the depth of a hundred feet. The de-
posit is usually in smaller quantity, but amounts in the
aggregate to millions of tons. The material was em-
ployed as a fertilizer by the natives of Peru and Chili,
long before its introduction into England or the United
States for the same purpose.
1024. DIFFERENT VARiETiES.-The qual-
Whatiisaid ... ...
of different ity of guano differs materially, according
to tlie source fr°m which it is derived.
The ammoniacal salts, on which its agency
as a fertilizer principally depends, being soluble in
water, the product of moist climates is of comparatively
little value. The best is obtained from the coast of
Peru, where rain seldom or never falls. The African,
Patagonian and other varieties, are much inferior.
In what does 1025' AGRICULTURAL VALUE.— The ag-
theagricui- ricultural value of guano lies principally
tural value . .
of guana m the ammonia and phosphate of lime
depend? which it is capable of yielding to plants.
These constitute, in the best varieties, about one-third
of the whole weight. Part of the ammonia is ready
formed, and part is produced in the subsequent change
which the nitrogenous matter of the guano experiences
in the soil. The latter may be produced immediately
by a chemical process, and its quantity accurately
determined. In estimating the value of guano, it is
customary to record the quantity of this potential am-
monia, as if it were an existing constituent.
SOILS. 409
What is said 1026. ARTIFICIAL AMMONIA. The COI1-
of the artifi- stituents of the ammonia which we pur-
cial produc- .. ~
tionofammo- chase, in the form of guano, at so great
expense and bring from distant regions of
the earth, exist in unbounded quantity at our very
doors. Four-fifths of the atmosphere are nitrogen gas,
and the ocean is an exhaustless reservoir of hydrogen.
But, strange to say, the chemist with all his skill,
cannot, except by circuitous and expensive methods,
effect their combination. The discovery of some cheap
and ready means of accomplishing this object, would
transform the face of the earth, by the unlimited quan-
tity of fertilizing material which it would supply. This
result may, perhaps, be reached by patient investiga-
tion. But no sudden triumph over nature need be
anticipated. Improvements in Agriculture will, as a
general thing, be only realized by the earnest co-opera-
tion of scientific and practical men, in laborious and
oft-repeated experiment.
1027. EXHAUSTION OF SOILS. — When
What is said i * « ,
of the exhaus- soils become exhausted 01 those substances
tion of soils? which form the mineral food of plants, the
growth of vegetation ceases. It is never absolute,
but consists in a great reduction of that portion of
their material which is in a condition to be appropri-
ated by the growing plant. Such soils are gradually
restored by rest. A gradual decomposition of their
insoluble material occurs by means of agencies which
have before been mentioned, and the soil is thus re-
stored to its original condition. These effects are very
much hastened by plowing in such a growth as can
18
410
ORGANIC CHEMISTRY.
be obtained. Rye, buckwheat, and clover are among
the plants best adapted to the purpose. Vegetable mat-
ter is thus added to the soil, which, in its decay, hastens
the decomposition of the soil itself.
What is said 1028. DEFICIENCY OF ONE OR MORE CON-
of defitien- sTiTUENTs. — The comparative exhaustion
ties in partic-
ular constitu- of some one or more of the constituents
of the soil, is a much more frequent oc-
currence. It is commonly the result of the cultiva-
tion of the same crop during many successive seasons,
and the consequent reduction of those materials which
the particular plant requires in largest proportion. De-
terioration of soils from this cause, is repaired by an
artificial supply of the failing ingredients. It is more
wisely guarded against by such a rotation of crops as
shall make different demands upon the soil in succes-
sive years.
What is said 1029. MAINTENANCE OF FERTILITY. -
°f the e/ect °f The effect of decomposing animal matters
decomposing
animal matter on the soil, has been already considered.
the soil ? return the very material which was
abstracted from the soil, with the addition of nitro-
genous matter, originally derived from the air by the
growing plant. In an enlightened system of rural
economy, the production of these materials in large
quantity and their careful preservation, is therefore an
object of paramount importance. The addition of
gypsum or dilute sulphuric acid to fermenting ma-
nures, is of great advantage in retaining their ammonia
in the form of sulphate, and preventing its escape into
the air. When additional ammonia is required, it is
411
most cheaply obtained in the form of guano. The
phosphates, whose quantity may be often increased
with advantage, are best supplied in the form of " super-
phosphate of lime." Other materials are less frequently
required. For further information on the subject of
the present section, the student is referred to works
which treat especially of Agricultural Chemistry.
1030. " SUPERPHOSPHATE OF LIME." —
What is said
of superphos- 1 he method employed in the manufacture
phateofiime? of « superphosphate of lime," has been al-
ready given in the chapter on Salts. As in the case
of guano, its agricultural value depends on actual or
potential ammonia, and phosphate of lime. In propor-
tion as the phosphoric acid is in a soluble form, the
value is much increased. Additional information on
this subject is given in the Appendix.
ANIMAL NUTRITION. 41.3
.'. ••--^-. •«,.-!-, ..'».
CHAPTER III.
ANIMAL CHEMISTRY.
ANIMAL NUTRITION.
1031. RELATIONS OF ANIMAL AND VEGE-
How is the
life of am- TABLE LIFE. — The life of animals is sus-
mah sustain. tained by the consumption of material
compounded and prepared by the plant,
and converted into its own substance, out of the mate-
rials of the earth and air. This is virtually true even
of the carniverous species, for the animals on which
they feed have derived their support from the vege-
table world. When they yield their own flesh as food,
it is only a changed vegetable matter which they thus
supply. All animal matter may therefore be regarded
as vegetable matter, more or less modified, or entirely
transformed by the processes of the animal body.
1032. FORMATION OF BLOOD. — The blood
tion of the material required for animal growth is
blood? - , . * . mi • • V
floated to its destination. This complex
fluid will therefore first engage our attention. The
food having been ground up by the teeth, and moist-
ened by the saliva, is conveyed to the stomach, and
414
ORGANIC CHEMISTRY.
submitted to the action of the gastric juice. Here it is
converted into a uniform greyish semi-fluid mass, called
chyme. The chyme is pushed forward by sponta-
neous contraction of the stomach. It yields its nutri-
tious matter, in the form of a milky liquid called
chyle, to minute absorbent vessels, distributed upon
the surface of the intestines. Through these absorb-
ent vessels it passes into the general circulation, and
is converted into blood.
What are the 1033. TRANSFORMATION OF THE FOOD.
offices of the The transformation of the nutritious por-
qastricand . ,, . . . , T . ~, 1
pancreatic tion of the chyme into chyle, is effected,
juices? jn partj j^ the gastric juice, and in part by
the secretion of the pancreas. The latter organ lies
back of the right end of the stomach, and pours its
secretions into the duodenum, or first of the small in-
testines. The gastric juice dissolves the protein com-
pounds of the food, while the secretion of the pan-
creas transforms the sugar and starch of the food into
grape sugar. The chyle is thus perfected, and pre-
pared to be drawn off from the refuse portions of the
food. As sugar forms no part of healthy blood, we
must suppose that it undergoes immediate transforma-
tion with fat or other material, as soon as it enters the
circulation. The office of the bile which is secreted
by the liver, and poured into the intestines, is not tho-
roughly understood.
1034. THE GASTRIC JUICE. — The saliva
To what is the ..... ..... -11 * * •
solvent agency which is mingled with the loocl in masti-
of the gastric cation has an effect similar to that of the
juice due ?
secretion of the pancreas. Another of its
THE BLOOD. 415
probable agencies is to introduce air into the stomach, to
act upon its lining membrane and produce from it one
of the constituents of the gastric juice. The solvent
agency of this fluid is in part owing to the ferment
thus formed, and in part to the free acids which it con-
tains in solution. The latter are phosphoric, hydro-
chloric, butyric, and lactic acids, in part free, and partly
in the form of salts.
1035. COMPOSITION OF THE BLOOD. —
Give the com-
position of the If fresh blood is beaten with a branched
blood' stick, it is separated into a slightly alka-
line liquid, called the serum, a fibrous material called
fibrine, and red globules, which sink, after a time, to
the bottom of the vessel. The fibrine adheres in threads
to the stick with which the operation is performed. It
is analogous, in composition and properties, to the vege-
table gluten from which it is formed. The serum con-
tains albumen, and resembles the white of egg. The
globules are also principally albumen, with a small
proportion of a red coloring matter called hematosine.
Albumen and fibrine both contain phosphate of lime or
bone earth. The serum contains, also, certain salts,
and a small proportion of fat. All of these substances
together form but about one-fifth of the blood ; the
remaining four-fifths are water. When blood is left to
stand, after being drawn from the body, the fibrine coag-
ulates spontaneously, entangling and taking with it the
red globules, and thus separating them from the serum.
1036. ANIMAL NUTRITION. — It is evident
What niateri- /. , -, . 1,1 -u
ah arc. found irom the preceding paragraph that much
ready formed Of the materjai required to build up the
in the blood ? r
body, is found ready formed in the blood.
416 ORGANIC CHEMISTRY.
It has been transferred to it from the vegetable world
without material change in composition. Thus the
fibre which is required for muscle and fat to fill out the
tissues, require only to be built into their places in the
animal frame, as a mason lays up a wall from materials
provided to his hand. For the production of other
animal substances, essential changes are required. The
power of selection and appropriation of the proper ma-
terials for every organ and every secretion, is found to
reside in innumerable minute cells, which are distributed
in every part of the body, and are endowed with pecu-
liar powers, according to the offices they are designed
to fulfill.
BONES, FLESH, &c.
1037. BONES. — Bones consist of earthy
What is the J
composition of matter, and a cartilagenous material com-
itThLnr iS monly known as gelatine. The bone
earth, or mineral matter, is principally
phosphate of lime, arid forms in mammiferous animals
about two-thirds of the whole weight. The remaining
third is cartilage. Either of these constituents may
be removed from the bone without effecting its shape.
By removal of the cartilage, a brittle, earthy frame-
work remains. By removal of the earthy material, a
perfectly flexible mass is obtained, of a form entirely
similar to that of the original bone. The first change
may be effected by long digestion in dilute muriatic acid,
and the latter by fire. If in the second process the car-
tilaginous matter is not entirely consumed, bone black
FLESH. 417
or animal charcoal is produced, the uses of which
have been already described.
Of what does 1038. FLESH. — Lean flesh or animal
flesh consist ? muscle is composed of fibrine, penetrated
by a liquid which forms four-fifths of the whole, and is
called flesh fluid, or juice of the flesh. It contains a
peculiar organic acid, possessing the flavor of broth,
crystalline substances called creatine and creatinine,
and certain salts. Being extracted by cold water and
then heated, it forms a nourishing and highly flavored
soup. Hot water coagulates its albumen, and prevents
its escape from the flesh. Gradual heating is on this
ground to be recommended in the preparation of soups,
while sudden exposure to a high temperature, both in
boiling and roasting, yield more nutritious and highly
flavored meats. The salts of potash prevail in the flesh
fluid, while those of soda are more abundant in the
blood. Unlike the blood, this fluid is acid in its re-
action.
1039. SKIN, TENDONS, LIGAMENTS. — The
What is said
of tendons and cartilaginous material above mentioned as
ligaments ? a const jtuent of bones, is transformed by
boiling water, without change of composition, into
gelatine or glue. The skin, cellular membrane, tendons
and ligaments of the body undergo the same change, and
yield the same product. Gelatine may even be prepared
from refuse leather, by first extracting the tannin, and
thus reducing it to the condition of the original hide.
The tannin obtained in the process may also be em-
ployed for tanning new hides. Hoofs, hair, horn, and
feathers, although very similar substances, are not thus
affected by boiling.
18*
418 ORGANIC CHEMISTY.
Wliat isgela- 1040. GELATINE. — Gelatine is soluble in
tine? water, and yields a stiff jelly on cooling
from a hot solution. On this property is based its use
in the preparation of jellies for the table. The com-
mercial article employed for this purpose and ordinary
glue are essentially the same.
1041. The substance known as isin-
Crive the com- 7 ., -I--I--II-IT <•
position and glass, is the dried air bladder of a species
°^ sturoeon5 au& forms m its natural con-
dition, a soluble gelatine. Gelatine contains
the four principal organic elements ; nitrogen and oxy-
gen being in somewhat larger proportion than in the
protein bodies. Hoofs, hair, and the other substances
above mentioned, contain sulphur in addition. Gelatine
is susceptible, like the protein bodies, of putrefaction,
and also of exciting fermentation. As starch is changed
into sugar by the action of dilute sulphuric acid, so by
the action of oil of vitriol, gelatine may be converted
into a sweet crystalline substance, called glycocoll or
sugar of gelatine.
1042. HIDES, TANNING. — A solution of
What chemical
combination gelatin forms, with tannin or tanmc acid,
tan~ a tenacious insoluble precipitate. The
tanning of leather depends on the forma-
tion of this insoluble compound in the hides which
are submitted to the process. They are im-
mersed for this purpose in an infusion of oak
and hemlock bark, until the combination has
taken place throughout the whole thickness.
They are thus secured against putrefaction
and converted into firm, elastic leather. Hides may
FATS. 419
also be preserved by soaking them in alum and after-
ward in oil. Soft chamois' leather is prepared by
working the skin with fat alone.
FATS.
1043. COMPOSITION. — We have already
What is said *
of the consti- seen that there are both acids and bases of
tutton of fats? pureiy organic origin, and that these may
combine like the similar compounds of inorganic chem-
istry, to form salts. The animal fats and oils are mix-
tures of such compounds in different proportions. The
principal of these organic salts are stearine, margarine,
and oleine. Stearine is solid, oleine fluid, and marga-
rine occupies a middle position between the two. The
difference of consistence in butter, lard, and tallow,
is owing to varied proportions of these three substances
which enter into their composition. Beside the fats
contained in other parts of the body, the brain and
nerves of animals contain, with albumen and water,
certain peculiar acids and fats.
1044. SEPARATION OF FATS IN OIL. —
How may the . IT- /•
constituents of The steariiie and oleine of whale oil sep-
°rated?Cpa' arate spontaneously in cold weather. The
cold which i£ sufficient to harden the for-
mer, leaves the latter in a fluid condition. This effect
is often observed in lamps during winter weather. The
case is quite analogous to the separation of cider into
alcohol and water, by freezing. The water congeals,
and leaves the alcohol fluid. Both separations are im-
perfect. As the alcohol produced by the above process
420 ORGANIC CHEMISTRY.
is diluted to a large extent with water, so the oleine
retains a considerable portion of stearine in solution.
1045. SEPARATION OF FATS IN TALLOW
How may the . . , . , f . ,
different fats AND LARD. — Stearuie is obtained from lard
and tallow on a similar principle. It har-
dens on partially cooling the melted fat,
forming a mass from which the fluid oleine may be sep-
arated by pressure. Stearine thus obtained is used in
the manufacture of candles, while the oleine forms
lard or tallow oil. The former has, of late years, given
place to stearic acid, procured from the same sources,
by means to be hereafter described. Margarine may be
separated from butter by similar heating and slow
cooling. It is regarded by some chemists as a simple
mixture of stearine and oleine. and not a distinct sub-
stance.
1046. GLYCERINE. — Glycerine is the base
cer'me? How of all the fatty salts which have been
is it made? mentioned. It is a viscid, sweetish liquid
containing the same elements as grape sugar, and in
nearly the same proportion. On removing the stearic,
and oleic acids from melted stearine, or oleine, it re-
mains in the liquid form. This removal may be ef-
fected by lime. The white lime compound floats
upon the water which is used in the process while
glycerine is dissolved.
How is stearic 1047. STEARIC ACID. — The compound
acid made? formed by lime, as described in the last
paragraph, if tallow has been used in the process, is a
mixture of oleate and stcrate of lime. From these,
stearic and oleic acids are liberated by the agency of
SOAPS. 421
diluted oil of vitriol. The material floats on the dilute
acid, gradually losing lime, and becoming transparent
by its action. Sulphate of lime or gypsum is formed
at the same time and sinks to the bottom of the vessel.
The stearic and oleic acids are drawn off while yet
warm, and run into cubical moulds. The latter is sub-
sequently removed from the mixture by gentle heat
and pressure. The remaining stearic acid is then re-
melted and allowed to cool slowly. It is thus ob-
tained in a brilliant white mass, of crystalline texture,
with the lustre of mother of pearl. This material is
principally employed in the manufacture of candles.
Its superiority to stearine for this purpose, consists in
the fact that it is less softened by heat. The two sub-
stances differ in their melting point about ten degrees.
1048. SOAPS. — Soaps are compounds of
How are pot- . ' .
ash and soda stearic and oleic acids with caustic potash
~ or soda'* They are Produced by boiling
fats with either of the alkalies, till the
mixture becomes nearly or quite transparent. The
glycerine which is expelled from the fats in the process,
remains mixed with the soap which is produced. Pot-
ash soaps are soft. Soda soaps may be converted into
a floating coagulum, and separated from the water used
in their preparation by means of common salt. This
method is employed to give them their hardness. The
action depends on the insolubility of the soap in salt
water. Salt added to potash soap seems to have the
* In the ordinary preparation for soap making, the lye is made to
pass through lime in the leach tub, that its carbonic acid may be par-
tially removed.
422 ORGANIC CHEMISTRY.
same effect. But its action in this case is due to a
double decomposition, in which a floating soda soap is
formed, chloride of potassium remaining in solution.
Soaps may be also made without the use of water, by
combining oil or fat with melted potash.
1049. LINIMENTS, &c. — Soaps are soluble
How are trans-
parent soaps in alcohol, forming the tincture of soap
which is used for bruises. With the ad-
dition of camphor, this tincture forms opo-
deldoc. Transparency is imparted to soap by the evap-
oration of an alcoholic solution of the well dried mate-
rial. Liniments are soaps prepared from ammonia and
oil by the simple agitation of the materials.
1050. PROPERTIES OF SOAPS. — Soaps
Explain the
cleansing ac- which are prepared, as above seen, from
tion of soap. ^ &nd ^ haye the property Qf dissol-
ving more of the same material. On this property
their cleansing effect principally depends. When they
are dissolved, a portion of the alkali becomes free by
the substitution of water as base. This free alkali
adds to the cleansing effect, by its own affinity for the
oils and other organic matter. Alkalies alone are not
equally effectual ; they tend to shrink the fibre of cloth,
and thus protect it against a perfect purification. The
strength of the tissue is at the same time gradually im-
paired.
MILK, BUTTER, &c.
1051. MILK. — Milk is analogous to
What is the . • T i • ,
composition of blood in compositon, as is implied in the
milk? office which it fulfills in the nutriment of
423
the young animal. But casein takes the place of the
fibrin of the blood, and fat is also found in milk, in
much larger proportion. This fluid also contains sugar?
which is peculiar in its character and has therefore
received the name of sugar of milk. Butter is pro-
duced by the coalescence of the small particles of oil
which are suspended in milk, and partially separated in
the cream. Chemically considered, it is a mixture of
oleine and margarine. On partially cooling melted
butter, the latter collects at the bottom of the liquid
oleine, which forms the other constituent ; a portion
at the same time remains in solution. Beside the
above substance, butter contains phosphates and other
salts, with certain neutral fats, from which it derives
its flavor.
1052. CHEESE. — On exposure to the air
Why is the . • . ,
curd separated for a considerable time, the sugar contained
by exposure? ^R mjjj£. -g partiaiiy converted in lactic acid,
and the casein is precipitated. One reason of this pre-
cipitation is to be found in the neutralization of the
free alkali of the milk. The casein having thus lost
its solvent, assumes the solid form. The coagulation
of milk may also be effected by rennet, which con-
sists of an infusion of the lining membrane of the
stomach of the calf. Its mode of action is not well
understood.
1053. SOLID MILK. — Milk may be
brought into the solid form by careful
pared? evaporation, with a moderate heat. It
must be constantly stirred during the process. A ma-
chine has been recently patented which secures all of
424 ORGANIC CHEMISTRY.
these objects. With the addition of a little soda and
gum, milk may be thus kept sweet in the solid condition
for many months. The addition of water is all that
is necessary to reproduce it in its original form.
CHEMICAL CHANGES IN THE ANIMAL BODY.
1054. Certain important changes which
What is said
of changes in are constantly occurring in the animal body
^animal remain to be considered. The body is
not the same in any two successive mo-
ments of its existence. Every breath exhales a por-
tion of its substance into the atmosphere, and every
effort, whether of brain or muscle, is accompanied by
some transformation in the material of which it is
composed.
1055. CHANGES IN THE BLOOD. — By com-
Mention cer-
tain changes paring the blood of animals with their
in the blood? foodj it win be evident that certain mate-
rials have been not only modified, but entirely trans-
formed in its production. Starch and sugar are impor-
tant constituents of the food, but. they form no part of
healthy blood. They are transformed into fat or other
material as soon as they enter the circulation, and in
this new form constitute the fuel from which the heat
of the animal body is derived. Other changes which
occur in the blood will be mentioned in subsecuient
paragraphs.
1056. ANIMAL HEAT. — The oxygen
What is the
source of an- which is necessary for the slow combustion
imalheat? Qf ^ materiai aDove mentioned, is taken
into the blood in the course of its passage through
RESPIRATION. 425
the lungs. It passes on with them, through the ar-
teries, into the minute capillary vessels which are
distributed throughout the body. In these vessels
their combination takes place, with the same produc-
tion of carbonic acid and evolution of heat, as if
the material were burnt in air or oxygen gas. The
carbonic acid thus formed is carried back to the lungs
in the venous blood, and there exhaled, through the
thin membrane of the air cells, and exchanged for a
new supply of oxygen gas. In view of the relations
of starch and sugar to the process of respiration, as
above shown, they have been termed the respiratory
constituents of the food.
1057. RESPIRATION. — In cold weather
What is said . .
further of res- a larger amount of oxygen is inhaled with
piratwn ? every breath, in consequence of the greater
density of the air. Respiration is also involuntarily
hastened, and the blood, from the two causes combined,
becomes more thoroughly impregnated with oxygen
gas. The transformation or combustion of the respi-
ratory constituents of the blood, proceeds more rap-
idly in consequence, and more internal heat is pro-
duced to oppose the external cold. This is one of the
provisions of nature by which the animal body is ena-
bled to resist the influence of the seasons and of cli-
mate. Labor has the same effect as cold in hastening
respiration and necessitating a larger supply of food.
What change 1058. CHANGE IN COLOR OF THE BLOOD.
of color does FrOm the fact that the globules of the
the blood ex- °
perience in the blood undergo a change of color in the
lunss- lungs, where oxygen is absorbed, it is pre-
sumed that they serve, by absorption of the gas, as the
426 ORGANIC CHEMISTRY.
medium for its conveyance through the body. As
a consequence of the changed color of the globules,
arterial blood is of a bright scarlet, while venous
blood is dark red. The same change of color which
takes place in the lungs, may be readily produced by
agitating blood drawn from the veins with air or ox-
ygen gas.
What is said 1059. RELATIONS OF FOOD AND TEM-
of therein- PERATURE. — In proportion as the draft of
tions of food „ . . n „ .
and tempera- & furnace is increased, more fuel must be
tore? supplied for its combustion. For the same
reason more respiratory food must be taken into the
system, in proportion as more atmospheric oxygen is
inhaled. The fact that a larger quantity is required in
northern climates thus receives a scientific explanation.
The preference entertained in arctic regions for cer-
tain kinds of food, is also accounted for by the same
necessity for increased resistance to the external cold.
The train oil and fat which the Greenlander con-
sumes with avidity, are a better fuel in the animal
body than the starch which form a principal part of
the food consumed in warmer climates. The chemical
reason of this difference is found in the fact, that
starch and allied substances contains oxygen in larger
proportion. They are, as it were, in their natural con-
dition, partially burned or oxidized substances.
1060. CHANGE OF THE ANIMAL TISSUES.
What change
takes place in In proportion to the muscular or nervous
lhlbodyTf activity of the animal, the substance of
the body is disorganized and returned to
the blood from which it was produced. From the
UREA. 427
blood it is finally removed by the kidneys, principally in
the form of urea and uric acid, and thrown off as waste
material from the system. These substances, although
organic, may be figuratively regarded as the ashes of
the consumed muscle and other nitrogenous constitu-
ents of the body. A portion of the carbon and hy-
drogen of the animal organs has at the same time dis-
appeared, like the elements of respiratory food, in the
form of water and carbonic acid.
What is 1061. UREA. — Urea, when " separated
said of Urea ? frOm its solution, is obtained as a white
crystalline solid. Its molecule contains four atoms of
hydrogen, to two each of carbon, nitrogen, and oxygen.
When left in contact with the mucus with which
it is accompanied in the secretion of the kidneys,
it is speedily converted, by combination with four
molecules of water, into carbonate of ammonia. Urea
may also be artificially produced from cyanic acid arid
ammonia. This cyanate is identical with urea in
composition, and is converted into urea by solution in
water and evaporation. It was among the first of
organic bodies artificially produced. Uric acid con-
tains the same elements with a larger proportion of
oxygen, and also yields ammonia by its decomposition.
Besides the above substances, the secretion of the kid-
neys contains various soluble salts, which have formed
part of the body. The insoluble salts are removed
from the system by other means.
1062. DISAPPEARANCE OF FAT. — STARVA-
What is said
of the disap- TioN. — Vv hen the supply oi respiratory
P™™nce °f food is deficient, nature avails herself of
the fat previously stored in the animal
428 ORGANIC CHEMISTRY.
body, as fuel to sustain tjhe animal heat. It is taken
up by the blood, and burned in the capillary vessels,
as before described. This happens in the case of the
bear and other hybernating animals. Lying dormant
during the winter season, their fat is consumed, and
they emerge lean from their dens in the spring. Where
food is deficient and there is no accumulation of fat to
supply its place, the muscle and other portions of the
body are consumed, and death by starvation is the con-
sequence.
1063. REPAIR OF THE TISSUES. — As fast
How are the
tissues repair- as the worn out matter of the muscles
and other organs is removed, its place is
supplied in the healthy body by new material from the
blood. Through it, also, the phosphates of the soil
and the vegetable world are transferred to the skeleton
of the animal, and in smaller proportion to other parts
of the frame. The blood is itself renewed by the
materials of the food.
1064. VARIETIES OF FOOD. — It is implied
Mention two
classes of in the foregoing, that the two classes of
food' substances which enter into the compo-
sition of the food of animals, subserve very diiferent
purposes in the animal economy. The first class, of
which starch and sugar are the principal, serve, by their
gradual combustion, to sustain the animal heat. They
are included, as above stated, under the general name
of respiratory food. The protein bodies, on the other
hand, all of which contain nitrogen, are appropriated
in the formation of blood and muscle ; they make up
the sanguineous or plastic food. In view of the fact
FOOD. 429
that the respiratory food enters also, in a changed form,
into the composition of the blood, the former term
can scarcely be regarded- as distinctive. The latter,
which designates the office of the protein bodies in
furnishing material to build up the organs of the body,
is much to be preferred.
1065. PROPORTIONS OF FOOD. — For the
What is said . ,,.,..,,
of the import- economical sustenance of animals, it is of
Proportion of imP°rtance tnat a proper relation of quanti-
thetwo kinds ty should be maintained between these two
varieties of food. Respiratory food alone,
provides no material for supplying the waste of the or-
ganized tissues. Plastic food, on the other hand, is es-
pecially adapted to this end, but is poor fuel for sus-
taining the heat of the body. Yet in lack of other
material, it is diverted from its natural use, and thus
appropriated at great economical disadvantage.
1066. Nature teaches us something on
What does na-
ture teach on this subject, in the composition of milk
this subject? amj tnose grains which constitute the
principal food of man. It will be found by reference
to the table in the Appendix, that the quantity of
respiratory matter in these substances, is from three to
six times greater than that of the plastic material.
When the object is to fatten an animal, the proportion
of respiratory matter may be considerably increased
by the use of potatoes, rice, and other farinaceous food.
Being furnished in excess, it accumulates in the body
in the form of fat. Working animals, on the other
hand, must be supplied with nitrogenous or plastic
430 ORGANIC CHEMISTRY.
food in large proportion. The use of bacon, with
peas, beans, and eggs, and many other popular mix-
tures of food, are accounted for on the principle above
stated. For the development of most of the views
presented in this chapter, the world is indebted to the
distinguished Liebig.
ORGANIC ANALYSIS
1067. ULTIMATE ANALYSIS. CARBON AND
How are car-
bon and hy- HYDROGEN. — The proportions of carbon
'mined ?deter~ an(^ hydrogen in organic substances, is
ascertained from the quantity of carbonic
acid and water which they yield on combustion. The
combustion is effected in a glass tube, by means of
oxide of copper, and the products are collected by
means similar to those described in the process for an-
alyzing the air.
1068. NITROGEN AND OXYGEN. — Thepro-
How are nitro- .... . ,
gen and oxy- portion of nitrogen m an organic substance
gendetermin- is usuany determined by the quantity of
ammonia it will yield by combination
with hydrogen. This combination is effected by
heating the organic substance with hydrate of potassa
or soda. The quantity of the ammonia produced in
the process is estimated by the amount of acid it will
neutralize. From the weight of this compound, that
of the nitrogen it contains is readily calculated. The
amount of oxygen in an organic substance is ascer-
tained by subtracting the total weight of all the other
constituents.
PROXIMATE ANALYSIS. 431
How are or- 1069. PROXIMATE ANALYSIS. When it
ganic bodies js desired to separate organic bodies from
fromlach each other, and determine their relative
other? proportion without reference to their ele-
mentary composition, the methods are analogous to
those of inorganic chemistry. Distillation, and the
analysis of the fats, which have been already described,
may be taken as examples.
CIRCULATION OF MATTER.
433
CHAPTER III.
CIRCULATION OF MATTER.
1070. The relations of the three king-
What proves ,.."*' . , .
the relation doms of nature have been already mciden-
tally considered in former parts of this
nature? work. It remains to present the subject
in a single view. It is obvious, at a glance, that the soil
does not furnish all the material which is required for the
wants of vegetable life. The level of our meadows
is not lowered by removal of successive crops, nor
does the forest dig its own grave at its roots as it lifts
its ponderous trunks into the air. The atmosphere,
as well as the soil, contributes to the increase of mass,
whether of wood or grain, and indirectly feeds all
races of animal existence. The relation of the three
kingdoms of nature is thus established.
1071. Water is one of the principal
How does wa- .
ter serve in agents in the system of circulation of
a/matte?/™ matter> which constitutes the life of the
globe we inhabit. In the fulfillment of its
office, it passes incessantly from sky to earth, now
mingling with the currents of the atmosphere, and
anon with those which form the arteries and veins
of the great world of waters. Lifted into the atmos-
19
434 ORGANIC CHEMISTRY.
phere by the sun, it descends again in dew and rain,
corroding and dissolving the rocks on which it falls,
and distributing them widely over land and sea.
1072. It settles through the stony crust
What distinct , . . . , , ,
office does it of the earth, into the dark recesses of the
fulfil? rocks where crystals blossom out of the
formless stone, and supplies them with the material
for their wonderful architecture. It penetrates the
soil, and supplies the same material to the roots of
plants for the still more wonderful creations of leaf,
and fruit, and flower. Again it hastens through
brooks and rivers on its course, and pours its burden
into the sea, for the use of the innumerable forms of
vegetable and animal life which inhabit its waters.
The coral insect builds up solid islands out of the mat-
ter it provides. Countless shell-fish clothe themselves
in the same rocky garments, and finally cast them aside,
to be buried under the slime of the sea and harden, in
the course of ages, into stone. The water which has
served these various offices, climbs anew into the
heavens upon the solar rays, and again descends in
the rain, repeating forever its round of service to the
earth.
1073. The further relations of the three
How may the n L , .
further reia- kingdoms of nature may be presented in
fhrll °king- a smgle picture. Imagine a giant tree, the
doms be i'llus- representative of all the vegetation of the
earth, spreading wide its branches as a shel-
ter for man and beast. Let us suppose them to subsist
entirely upon its fruit, and to warm themselves by fires
made from its branches. The tree, through its leaves,
CIRCULATION OF MATTER. 435
draws its supply of gaseous food from the atmosphere,
and through its roots, its mineral sustenance from the
soil. It has purified the air in the process, of gases
which would become noxious by accumulation, and
returned to it the oxygen which is the vitalizing breath
of the animal world. The mingled material of its
food, worse than worthless to animals, has, at the same
time, been transformed into wood and fruit, and other
forms of vegetable matter.
1074. At this point, without interruption
Explain the .
return of mat- m the circuit, commences the return of
mros°here "*' material to tne atmosphere from which it
was derived. Animals that feed upon the
fruit of the tree, already breathe much of it back
again to the air, while they live, and the rest is re-
stored by their death and subsequent decay. Leaves
that fall and moulder, and branches that are burned as
fuel, make the same return of the elements of which
they are composed, to the great reservoirs of the at-
mosphere and earth. And what happens thus to leaf
and fruit, happens also at last to the parent tree itself.
One by one its giant branches fall and moulder, and
melting again into the air, add to its inexhaustible
stores of fertility, and provide the material for a new
round in the grand system of circulation.
1075. — What happens beneath the single
Illustrate the
extent of these tree, occurs also in every flower that lifts
relations. ^ petals to the sun, and is a thousand
times repeated in every forest upon the face of the earth.
No limits of distance or of size, restrict the mutual rela-
tions and dependencies of nature. The exhaled carbon
436 ORGANIC CHEMISTRY.
of the polar bear feeds the lotus of Egyptian plains,
and the breath of the southern lion is redistilled in the
fragrance of the Norwegian pine. The particle of mat-
ter that once burned in the fire of the poet's brain, and
floated with his song upon the air, now blooms in the
mountain flower and anon lies buried in its mould.
1076. According to the view thus pre-
What is the
material sour- sented, it will be seen that the sun is the
If the ^orlf? §reat material source of the life of the world.
He wings the vapors that rise from the sea,
and fall again to make their ministering circuit in
the earth. The solar rays are the agents also, in the
transformation of matter, which takes place in every
leaf and blossom, and provide the animal kingdom with
its food.
1077. No less is the sun the source of
Show how it is , ., , , t • i • -,
the source of all the mechanical power which is known
UP°n the earth' The falling fl°°d °f N1~
agara is but the recoil of the spring which
is bent in evaporation from the sea and earth. All
force which is derived from the fall of water, is
thus traceable to the sun, which lifted it in the form of
cloud and vapor. The energies of fire and steam, are
only other forms of the force inherent in the solar rays,
originally exercised in the organization of the vegetable
matter which serves as fuel. Immediately produced
by oxidation, and the heat which it evolves, they find
their ultimate source, as well as their precise equivalent,
in the deoxidizing influence of the solar rays. The
forces of the human body are fed by consumption of
similar materials, and may therefore be traced to the
same source.
CIRCULATION OF MATTER. 437
1078. Every planet that surrounds with
What further
influence has its orbit the great centre of our system, is
equally dependent upon his influence.
Held in their courses by his attraction, and encircling
him in ceaseless revolution, they draw from the parent
orb the strength and beauty which clothes their
lesser spheres. What wonder, that in vague acknowl-
edgement of his influence, heathen have acknowledged
the sun as their God, and worshipped at his shrine.
How natural that Christian nations should find in his
life-giving power, a fitting emblem of the glory and
beneficence of the great Father of the Universe, by
whom all suns and systems, are, and were created.
APPENDIX. 439
APPENDIX,
IN this Appendix are included formulae descriptive of chem-
ical reactions of the text, and other matter no less important,
whose introduction into the text would have interfered in a
measure with the plan of the work.
The formulae constitute a precise statement, in the lan-
guage of the symbolical nomenclature, of the reactions al-
ready described in more general terms. It is not to be
understood from the formulae that the materials concerned
in any process must always be brought together in the pre-
cise proportions indicated in the first member of the equation.
One or the other may be in excess ; if so, the excess is null, and
not considered in the formula. The latter regards and indi-
cates only the relative quantities which are actually concerned
in each reaction — the first member having reference to the
materials employed, and the latter to the products.
Interpreted according to the atomic theory, each formula
gives on the one side of the equation, the nature and rela-
tive number of the atoms or molecules which take part in
any reaction, and on the other, the nature and relative num-
ber of those which result.
The student will do well, as an occasional exercise, to cal-
culate from the formulae the relative quantities of materi-
als required in a reaction, and of products resulting from it
in pounds and ounces. A T in the tables stand respectively
for acetic and tartaric acids.
440 APPENDIX.
§160.
The numbers given in the text are only approximations.
The exact quantities may be readily calculated by the law
of expansion and contraction of gases, and vapors previously
given, taking the volume of steam at 212° (§ 232,) as a start-
ing point.
§ 232.
According to the most recent determination, by Regnault,
the latent heat of steam is 966'6°. According to the same
experimenter the sum of the latent and sensible heat is not
rigorously constant.
§ 235.
The apparatus commonly employed in the laboratory for
distillation, consists of
a retort and receiver,
as represented in the
figure. In Liebig's ap-
paratus, for the same
purpose, the vapors are
made to pass from the
retort or flask through
a long inclined tube. The latter is enclosed in a second tube,
which is constantly supplied with cold water. A more per-
fect condensation is thus effected.
§248.
ACTIVE FORCE or THE GALVANIC CURRENT. — The active
force of the galvanic current, is directly as the whole electro-
motive force in operation, and inversely as the sum of all the
APPENDIX. 441
impediments to conduction. The above is Ohm's law. By
the electro-motive force, is to be understood the whole force
generated by the chemical action in the battery. The im-
pediments are found in the imperfect conducting power of
the bodies, whether liquid or solid, which enter into the cir-
cuit, and the resistance which the current encounters in
passing from one to another.
§ 273. (1.)
SMEE'S BATTERY. — Of all the batteries in common use,
Smee's, which is represented in the figure,
is the simplest. It consists of a plate of
silver, with plates of zinc hanging near it
on either side. The two zinc plates com-
municate with each other by a metallic
connection, and are, therefore, but one
plate. It is found best to roughen the
silver with platinum black. Smees' bat-j
teries are commonly sold in this condition.
The clamp and bar are simply to keep the
plates in place. Water acidulated with
from one-seventh to one-sixteenth of its bulk of oil of vitriol,
is employed in this battery. It is generally used in plating,
and is recommended to the student on account of its cheap-
ness, simplicity, and efficiency.
§ 273. (2.)
GROVES' BATTERY. — In Groves' battery the metal plati-
num is used, instead of copper or silver. It is placed by
itself, in a porous earthern cup containing nitric acid. The
vessel is placed in a larger one, containing zinc and sulphuric
acid. The two acids mix to some extent through the pores
of the inner cup, so as to complete the circuit by their con-
19*
442 APPENDIX.
tact. Without this the battery could not ope-
rate. The figure represents Groves' battery,
with the thumb screws by which the wires
are connected with the platinum and zinc.
The outer dark portion within the cup is the
zinc, divided from top to bottom, that the acid
may flow freely, and come into contact with
both sides.
§ 307.
THE ATOMIC THEORY. — That combination takes place in
definite and multiple proportions, is directly proved by exper-
iment. Oxygen, for example, unites with hydrogen in the
proportion of 8, 16, 32 and 40, to one of the latter element,
and refuses to combine in any other proportion. If matter
were infinitely divisible, no reason can be assigned for this
fact. Each infinitesimal portion of oxygen possessing the
same affinities, we should expect to find combination in exact
proportion to the quantity supplied.
Dalton's atomic theory, the truth of which is assumed in the
text, affords a luminous explanation of the facts under consid-
eration. According to this theory, oxygen combines with hy-
drogen in no smaller proportion than that of 8 to 1, because
this is the ratio of weight in the least existent particles of the
two substances. It combines in the proportion of 16, 24, 32
and 40, by uniting 2, 3, 4 or 5 of its atoms to one of Hydro-
gen. It refuses to combine in any intermediate ratio, be-
cause its atoms are indivisible. The same view of the con-
stitution of matter is essential to the explanation of innumer-
able facts in organic chemistry.
The value of a table of atomic weights does not depend in
the least degree upon the reception of the atomic theory.
It is a list of combining proportions, determined by careful
APPENDIX. 443
analysis, and reduced to a simple standard of comparison.
Its truth is independent of all theory.
RELATIONS OF ATOMIC WEIGHT AND DENSITY. — The com-
parative weight of equal measures or masses of different sub-
stances is not necessarily the same as the comparative weight
of their atoms. The mass of iron, for example, is heavier,
while the atom of iron is lighter than that of potassium. To
account for the fact, we must suppose the lighter atoms of
iron so closely arranged that they thus more than make up
by their larger number, for their inferior weight. In solids
generally, there is no correspondence between atomic weight
and specific gravity ; but in the case of many elements which
exist in the gaseous state, or are capable of assuming it, the
correspondence is complete, as shown in the following para-
graph.
COMBINING MEASURES OR EQUIVALENT VOLUMES. — A cubic
foot of nitrogen, weighs just fourteen times as much as the
same measure of hydrogen, and the relation of the atomic
weight is the same. In combining by atomic weights or
equivalents, they therefore combine in equal measures.
Chlorine, and the vapors of bromine, and iodine, belong
to the same class. Taking hydrogen 1 as the standard,
their combining measures are all 1. In the case of oxygen
the correspondence referred to does not exist. It is sixteen
times as Iieavy as hydrogen, while its atom weighs but eight
times as much ; here again we are under the necessity of
supposing a closer arrangement of the atoms. Those of
oxygen are not only heavier, but twice as closely approxi-
mated. Taking hydrogen as the standard, the combining
measure of oxygen is therefore £. That of phosphorus arid
arsenic is the same, and that of sulphur^-. In the case of
most other substances the ratio is not so simple.
In the comparison of combining measures it is more
customary to adopt oxygen as the standard of unity. The
444 APPENDIX.
combining measure of hydrogen, chlorine, etc., becomes
2, as a consequence, and that of other gases or vapors is
proportionally changed. In the production of compound
gases, the elements either suffer no condensation or experi-
ence a very simple change of volume. Thus hydrochloric
acid gas, formed by the combustion of hydrogen and chlo-
rine, possesses the united volumes of its constituents.
EQUIVALENT VOLUMES OF COMPOUND GASES. — As the
equivalent, or combining proportion of a compound, is
equal to the sum of the equivalents of its constituents, it
follows that the combining measure of hydrochloric acid,
is equal to the sum of the combining measures of hydro-
gen and chlorine, 2+2 = 4. Ammonia is formed by the
union of three volumes of hydrogen, and one of nitrogen.
Condensation takes place to the amount of £ of the whole
volume of their mixed gases. The combining measure is
therefore equal to the sum of the combining measures of the
constituents divided by 2. The sum of the combining
measures is 8. 8-7-2=4. Steam is composed of one com-
bining measure (two volumes) of hydrogen, united with
one combining measure or volume of oxygen, and condensed
to two volumes in combination. Its combining measure is
therefore 2. The above instances may serve as examples
of the interesting relations of atomic weights, specific quan-
tity, and combining measures.
CALCULATION OP SPECIFIC GRAVITY. — The density or spe-
cific gravity of a compound vapor or gas of known propor-
tional composition, may be readily calculated from that of
its constituents, supposing the amount of condensation which
takes place in their combination to be known. The results
thus obtained, are more accurate than any results of experi-
ment. In like manner the proportional composition of a
compound may be calculated from a knowledge of its ele-
ments and density. The density of the vapor of carbon and
APPENDIX. 445
other solids which are not known in the gaseous form, may
be calculated from the density of their compounds with ele-
mentary gases of known density. That of carbon, for ex-
ample, may be deduced from that of carbonic acid. The
calculation involves an assumption as to the equivalent vol-
ume of carbon. Assuming it to be the same as that of hy-
drogen, the density of carbon vapor is 423 '4. If its equiva-
lent volume is the same as that of oxygen or £ that of hydro-
gen, the density is doubled.
ATOMIC VOLUMES. — It is obvious that the number of atoms
of a given weight in any mass, must be in proportion to the
density of the mass. The size of the same atoms must be
less in the same proportion. The atomic volume of any
substance is therefore obtained by dividing the atomic
weight by the density or specific gravity of the body. The
subject of atomic volumes has important relations to the
science of crystallography. In comparing atomic volumes
it is assumed that the space which a body occupies is com-
pletely filled by the atoms, without intervening space.
ATOMIC HEAT. — The numbers 28, 32, 103, represent, in
the order in which they are given, the atomic weights of
iron, copper, and lead. It is a remarkable fact that if the
three metals be taken in these relative proportions, it will
require the same expenditure of heat to make them equally
hot. 103 pounds pounds of lead can be heated up to 212,°
for example, by burning the same amount of alcohol which
will heat 32 pounds of copper, or 28 Ibs. of iron, to the same
degree. Most other metals, and the non-metallic element,
sulphur, come into the same class, or in other words,
have the same atomic heat. The atomic heat of arse-
nic and silver is double that of the elements above men-
tioned. Other elements are different in this respect, but
commonly by some simple ratio of difference. The cor-
respondence is never absolute, but so close as to have lead
446
AXPENDIX.
many chemists to attribute the variations to errors of exper-
iment, and to regard the law of correspondence of atomic
weights as universal.
§ 313.
CALCULATION OF FORMULAE. — The student interested in
the subject will readily devise for himself the reverse pro-
cess of calculating formulae from the per centage results of
analysis. The formulae obtained must obviously be such,
that if reconverted into per cents, the numbers obtained will
agree very nearly with the results of analysis. There may
sometimes be a doubt whether the simplest formula which
will express the composition, or some multiple of it is the
true one. This can only be decided by the analysis of one
of the compounds of the substance in which the formula of
the second constituent is established.
The reasoning will be best illustrated by an example. It
being assumed that neutral salts contain one equivalent of
base to one of acid, the analysis of the neutral sulphate of
potassa would establish the formula for sulphuric acid, SO,
instead of SaOe. KO,SO3 would express correctly the com-
position of the salt, while the substitution of SsOe for SsOa
in the same formula, would give a double proportion of acid.
§ 323.
When the same element unites with oxygen in different
proportions to form different acids, these are distinguished
by prefixes and terminations, which indicate the order in
which they stand to each other, with respect to the quantity
of oxygen.
The first acid of such a series discovered, generally receives
the termination " ic." Chloric acid may serve as an exam-
pie. Another acid compound of chlorine since discovered,
" IlvS'l^'
^*
APPENDIX. 447
and containing more oxygen, is called hyperchloric, signify-
ing higher than chloric. The other names of the list indi-
cate, by their prefixes and terminations, the order of oxy-
geriation of the several acids. The same means of distinc-
tion are employed in other series.
Hypochlorous acid, - - -»Vv CIO.
Chlorous acid, ''•" - :V - - ClOa.
Hypochloric acid, (peroxide of chlorine,) C1O4.
Chloric acid, 'lTi-;H ClOs.
Hyperchloric acid, ... • *vr < ClOr.
§332. KO,C1O5=KC1+6O.
§334.
§338.
§340. C+2O=CO2.
§354. 2HCl+MnOa=2HO+MnCl+Cl.
§355. (CaCl+CaO,ClO)+2SO3=2(CaO,SO3)+2Cl.
§358. Sb+5Cl=SbCls.
§ 362.
It will be observed, on comparing § 362 with those which
precede, that chlorine sometimes expels oxygen, and is
sometimes expelled by it. In relation to the apparent in-
consistency of these facts, litrle more can be said than that
chemical affinities are modified by circumstances, the action
of which is not perfectly understood.
§365. HO+C1-HC1+O.
I 375. NaI+2SO3+MnO2=NaO3SO3+MnO,SO3+I
§384. S+2O=SOa.
§400. Zn+HO,SO3 = ZnO, SOs+H.
§408. Cu+2SO3=CuO, SOa
448 APPENDIX.
§ 411.
IODIDE OP NITROGEN. — Iodide of Nitrogen, a very explo-
sive compound, is formed when an alcoholic solution of iodine
is added to aqua ammonia. It precipitates in the form of a
black powder. The precipitate should be thrown upon a
filter, washed, and while still moist, divided into small por-
tions for the purpose of experiment. When dry it explodes
violently by simple touch, and sometimes even spontaneously.
CHLORIDE OF NITROGEN. — Chloride of nitrogen is a still
more dangerous compound than the above. To prepare it
ajar filled with chlorine gas is suspended over a solution of
sal ammoniac, contained in a leaden saucer. After the lapse
of a few hours, an oily liquid forms and falls to the bottom
of the solution. This is the chloride of nitrogen. Mere
contact with a combustible material, such as fat, oil, phos-
phorus, &c., is sufficient to cause its explosion. • A single
drop of the liquid explodes so violently as to shatter to pieces
any earthen or glass vessel upon which the explosion takes
place. The preparation of this compound cannot be recom-
mended ; in the hands of the ablest experimenters it has
been the occasion of the most dangerous accidents.
§413. P+5O=POs.
§ 424. KO, N05 +HO, S03=KO, SCh+HO, NO5.
§425. 3Cu+4N05=3(CuO, NO5)+NO2.
§426. NO2+2O=NO4.
§428. 3Sn+2NO5=3SnO3+2NO3.
§430. 3P+5NO5=3PO5+5NO2.
§433. 5C+PO5=5CO+P.
§ 446. AsCls +6Zn + 6(HO, SQ3) = 6(ZnO, SOs +
3HCl+AsH3.
§464. C+2O=CO2.
§465. HCl+CaO,CO2:=HO+CaCl+CO2.
APPENDIX. 449
§478. C
§480. CaOs, HO+SO3=HOSO3+CO2+CO.
§490. Zn-{-SO3+HO2=ZnO, SO3+H.
§492. 3Fe+4HO=Fe3O4+4H.
§496. H+O=HO.
§501. Na+HO=NaO+H.
§519. H+C1=HC1.
§521. HO,SOa+NaCl=NaO, SOs+HCl.
§530. SiO3+3HF=3HO+SiF3.
§537. N+3H=NH3.
§539. CaO+NH4Cl=HO+CaCl+NH3.
§543. NH3+HC1=NH4C1.
§546. KO+3HO+2P=KO,PO3+PH3.
§ 553. 2SO3+C4H5O2=2(HO, SO3)+C4H4.
§577. 2C+KO,CO2=3CO+K.
§585. Na+NH4Cl + Hg
§626. Sb+5Cl=SbCl5.
§ 680.
The other elements not mentioned in the text are glucinum,
cadmium, cerium, colnmbium or tantalum, didymium, erbi-
um, indium, lanthanum, molybdenum, niobium, norium,
osmium, palladium, pelopium, rhodinm, ruthenium, seleni-
um. tellurium, terbium, thorium, titanium, tungsten or wol-
framium, vanadium, ytrium, and zirconium. With the ex-
ception of selenium and tellurium, which are analogous in
their properties to sulphur, they may be classed with the
metals. They are of rare occurrence, and may be regarded
as sustaining the same relation to the other elements as do
the asteroids and satellites to the more important members
of the solar system.
§646. Zn+PbO, A=ZnO, A+Pb.
§665. NaCl+AgO, NO5=NaO,
450 APPENDIX.
§685.
NEUTRAL, ACID, AND BASIC SALTS. — In general, salts con-
taining an equivalent of base to an equivalent of acid are
called neutral. The composition fixes the name, whether ex-
actly neutral to the taste and in their action or vegetable
colors, or not. Salts containing more acid in proportion
are called super-salts or acid salts, and those containing
mere base, sub-salts or basic salts.
There are two exceptions to the above rules. The first
is that of certain classes of acids which have double and
treble neutralizing power, and require, therefore, the first two
atoms, and the latter three atoms of base, to make them
neutral salts. Such acids are bibasic and tribasic, in contra.
distinction from the mono-basic or ordinary salts. Phospho-
ric acid is one of the latter class of tribasic acids, and the
neutral phosphates have therefore three atoms of base and
is called a tribasic phosphate. Phosphates containing more
acid or base than their proportion, are acid or basic accord-
ing1 y-
The second exception is that of salts or bases which con-
tain more than one atom of oxygen to an atom of metal.
In proportion as they contain more, they neutralize more acid.
Alumina or oxide of aluminium, for example, contains three
atoms of oxygen. Its neutral sulphate, therefore, is a salt
containining 3 atoms of acid. A salt of aluminium containing
more or less than their proportion, is acid or basic accord.
DOUBLE SALTS. — There are also double salts or compounds
of salts with each other. They are generally of the same
acid. Thus alum is a double sulphate of potassa and alu-
mina and the bisulphate of potassa may be regared as a
double sulphate of potassa and water. Such double salts
APPENDIX. 451
are not mere mixtures. They have their own crystalline
form, and each particle of their crystals contanis all the ele-
ments of both.
BINARY THEORY OP SALTS. — Sulphate of potassa, and
other similar salts, are commonly regarded as ternary com-
pounds. But many chemists are of the opinion that they
are constituted after the plan of the binary salts, and their
acids on the plan of a hydrogen acid. They would write
sulphuric acid, SO4,H, instead of HO,SOs, thus indicating
that the hydrated acid is composed of the radical, S(X (a
compound playing the part of an element,) with hydrogen.
Sulphate of potassa would, according to this view, be writ-
ten K,SO4, instead of KO,SO3. The acid and salt are thus
represented as analogous in constitution to a hydracid and
a binary salt; thus, (SO4)H corresponds with C1H, and
K(SO4) with KC1. The advantage of this view is that it
makes but one great class of acids, and one of salts, associ-
ating substances which are analogous in their properties.
Hydrogen thus becomes characteristic of an acid. This view
also simplifies the subject of the production of salts from
acids, making it to consist simply in the replacement of the
hydrogen of the acid by a metal. Thus in the action of sul-
phuric acid (HO.SOa) on zinc, sulphate of zinc (ZnO,SOs) is
formed by the simple replacement of the hydrogen of the
acid by the metal zinc. As will be seen more clearly in
the introduction to Organic Chemistry, it is no conclusive
objection against the view, that the radical SO4 has not been
isolated. There is the best reason for believing in the exist-
ence of many such hypothetical radicals. A similar objection
has indeed been urged against the ordinary view, according
to which SOs neutralizes potassa in the sulphate of this base.
The objection lies in the fact that anhydrous sulphuric acid
is not possessed of acid properties, and can therefore be
scarcely regarded as an acid, in its anhydrous condition.
452
APPENDIX.
§717. CaO, HO+KO, CO2=CaO, COa+KOHO.
§725. NH3+HO,SO3=NH4O, SOs.
§726. CaO, CO2=CO2+CaO.
§ 727. CaO+HO=CaO, HO.
§741. HCl+NaO=HO+NaCL
§742. NaCl+AgO, NO5=NaO, NO^+AgCl.
§748. (CaCl+CaO,ClO)+2CO2=2(CaO, CO«)+2C1.
§750. 2CaO+2Cl=(CaCl+CaO, CIO).
§751. 3C+3Cl-fAl2O3=3CO+Al2Cl3.
§760. HO, SO3+CaF=CaO, SOs+HF.
§762. PbO, A+HS=HO, A+PbS.
§ 769. NaO+SO3=NaO, SO. Vide §400.
§770. (CaO, SO3+2HO)=2HO-fCaO, SOs.
§772. 2HO+CuO, SOs = (CaO, SOs+2HO).
§774. HO, SO3+NaCl=HCl+NaO, 80s.
§775. Glauber's Salt=(NaO, SOs + lOHO).
§777. Alum=(KO, SOa+AlaOa, 3SO+24HO).
§778. (KO, SOa + AlaOs, 3SOs+24HO)=24HO +
(KO, SOs+AhOs, 3SOs).
c77Q (ChromeAlum=(KO,SO3+Cr2O3,3SO3+24HO.
'< Ammonia Alum=(NH40, SOa+AlaOs, 3S03+24HO).
f Sulphate of Zinc =(ZnO, SOa+7HO).
§780.-! Sulphate of Copper^ (CuO, SOs+5HO).
[Sulphate of Iron=(FeO, SO3+7HO).
§783. Nitrate of Potash (Nitre) =KO, NO5.
§784. CaO,NO5+KO,CO2=CaO,CO2+KO, NO5.
§786. NH40, N05=4HO+2NO.
§787. S+KO, NO7+3C=KS + N+3CO2.
§789. Nitrate of Silver (Lunar Caustic)=AgO, NO*.
§ 790. Nitrate of Soda^NaO, NO*.
§792. KO, CO2+CaO, NO5=KO, NO5+CaO,CO2.
§795. CaO, CO3+NaS=CaS+NaO, C02.
§ 797. Sesqui-carbonate of Ammoma=2NH40, 3CO2.
APPENDIX. 453
§804. CaO+C02=CaO, CO*.
§ 809. (2NaO, HO, P05 + 24HO) + 3(AgO, NO 5 =
2(NaO,NO5) + HO,NO5+24HO+3AgO,PO5.
§ 824. Biborate of Soda=(NaO, 2BO3 + 10HO).
§ 828. Chromate of Lead (Chrome yellow) = PbO, CrO 3 .
§829. KO, C02 + 2(PbO, Cr03)=KO, Cr03+CO2 +
2PbO, CrOs.
§ 830.
Commercial chrome green is a mixture of Prussian blue
and chrome yellow.
§833. 3(KO, MnO3)+2S03=2(KO, S03)+MnO2-f
KO, Mn2O7.
§ 845. 4NO5+3Ag+Au=3(AgO, NOs)+NO2+Au.
§ 846. 3NH4O + CaO, NO5 + A12Q3, 3NO5 =
3(NH4O, NO5)+CaO,NO5+Al2O3.
§ 847. CuO, NO 5 + AgO, NO5 + HC1 = CuO, NO 5 +
HO, NO«+AgCl.
§877. Woody Fibre = CiaHioOio.
§890. Kreosote==Ci4H802.
Carbazotic
§894. Gun Cotton (Pyroxalme)=Ci2H808, 4NOs. ?
§898. CJ2HioOio+4HO=Ci2Hi
§900. Starch=Ci2HioOio.
§904. Ci2HioOio+4HO=Ci2Hi
§907. Grape Sugar=Ci2Hi4Oi4.
§908. Cane Sugar=CiaHnOii.
§913. (Ci2Hi2
4CO2.
§914. Alcohol=C4HeOa.
§917. C4
454
APPENDIX.
§ 919.
FULMINATES. — This name has been given to a class of
highly explosive salts, obtained by the action of alcohol
upon certain nitrates. The most important are the fulmi-
nates of mercury and silver. Fulminating mercury is pre-
pared by dissolving 1 part of mercury in 12 parts of nitric
acid, sp. grav. 1.36, and subsequently adding 11 parts of 80
per cent, alcohol. Upon warming the mixture a compli-
cated reaction takes place, dense white vapors are given off,
and the fulminate is thrown down as a crystalline powder.
This is to be washed with cold water and afterwards dried
at a moderate temperature. This salt explodes violently by
heat, friction, or percussion, and sometimes even without
any apparent cause. It is largely employed in the manufac-
ture of percussion caps, torpedoes, &c., &c. Fulminating
silver detonates still more violently than the mercury salt.
By friction with a hard body, it explodes even under water.
It is prepared as above, using 10 parts of nitric acid and
20 parts of alcohol. Too much caution cannot be observed
in manipulating with these highly dangerous compounds.
They should be prepared only in quantities of a few grains.
Fulminate of Silver=2AgO, CyaOa.
§927. Ether=C4H5O.
Alcohol =C 4 HeO2 or (C4H5O+HO).
§928.
§929.
§930. C4H6O2+2S03=2(HO,
§931.
§932.
§933.
§935. Chloroform- C 2 HCFs.
§938. Tannic Acid=Ci 8H5O9, 3HO=Qt, 3HO.
APPENDIX. 455
§941. Cyanogen=C2N=Cy. An arbitrary symbol.
§942. FeCy, 2KCy+HgCl2=FeCy,2KCl + Hg+2Cy.
§943. Cyanide of Potassium==KC2N=KCy.
§944. Prussian Blue = Ci 8N9Fe7 = Fe4Cfy3.
fFerrocyanogen=3Cy, Fe=Cfy.
§945.j Ferrocyanide of Potassium = (3Cy, Fe+2K) =
I Cfy,2K.
§ 946. 2(3Cy, Fe + 2K) - K = (2(3Cy, Fe) + 3K) =
2Cfy, 3K.
§947. KCy+HO, SO3=KO, SOs+HCy.
fTartaric Acid=CsH4Oi o, 2HO=T, 2HO.
Oxalic Acid=C2O3, HO=O, HO.^
.Citric Acid^CisHsOn, 3HO=Ci, 3HO.
49>1 Malic Acid=C8H408, 2HO-M, 2HO.
Formic Acid =C 2 HO 3, HO.
LLactic Acid=C6H5O5, HO.
§ 975.
In the present state of our knowledge in respect to the
protein bodies, we must abandon every formula by which
their atomic constitution is said to be expressed. Generally,
they contain in 100 parts : 55.16 carbon, 7.05 hydrogen,
21.81 oxygen, 16.96 nitrogen, with £ to 1 per cent, sulphur
and phosphorus in an unknown form.
Morphine^CssHaoNOe.
C44H23N2O8 or
|Quinine=C2oHi2N02.
[Theine and Caffeine=Ci aHi oN40.
§993. Indigo=Ci6H5NO2.
§ 994. Alizarine = C 2 o H i o O i o .
§995. Hematoxyline — C4oHi ?0i s.
§1002. Vide §994.
456 APPENDIX.
§ 1003. (KO, SOs + Cr2O3, 3S03) + 3KO = 4(KO;
SO3)+Cr2O3.
§ 1025.
MODE OF ESTIMATING THE VALUE OP GUANO, &C. In
estimating the money value of guano for agricultural pur-
poses, ammonia may be set down at 16 cents per pound,
potash at 4 cents, and phosphoric acid at 1£ to 2 cents. As
far as the latter exists in a soluble form, its value is doubled.
Other substances are of so little comparative value that they
need not be taken into the account. These valuations are
based, not alone on their relative value as fertilizers, but on
the cost of the different substances when obtained from other
sources. They are somewhat arbitrary, but may serve as a
means of approximate estimation of the value of guano and
other fertilizers.
As an average of the composition of thirteen samples of
Peruvian guano, Prof. Way obtained the following results :
ammonia, 17*41 pgr cent.; phosphoric acid, 11-13; potash,
3*50. This would seem to be considerably above the or-
dinary average. The pecuniary value of such an article,
according to the above valuation, would be $63.00 per ton,
of which 855.60 would lie in the ammonia. No distinc-
tion is made in the potential and actual ammonia of guano,
because the conversion of the former into actual ammonia,
takes place so rapidly in the soil. But the potential ammo-
nia of most nitrogenous substances, as of clippings of hides
and other similar refuse, is to be estimated at least 25 per
cent, lower, in view of their comparatively slow conversion.
In all analyses of concentrated fertilizers excepting guano,
in which the first distinction may be neglected, the amount
of actual and potential ammonia, of soluble and insoluble
phosphoric acid, and of potassa, should be separately stated.
APPENDIX. 457
The latter constituent is, however, of comparatively little
importance. The farmer who purchases his artificial fer-
tilizers without a skillful and well attested analysis, is at the
mercy of the ignorant or unscrupulous dealer.
§ 1 046. Glycerine = C 6 H e O c .
fStearic Acid^CesHeeOe, 2HO=St, 2HO.
§1047.<{Margaric Acid^Cs^ssOs, HO.
[Oleic Acid^CseHssOa, HO.
$Urea=C2N2H403.
I Uric Acid=CioN4H305+HO.
APPENDIX.
459
TABLE L
TABLE OF THB DISCOVERY OF OKRTAEf ELEMENTS.
Authors of the discovery.
Dates.
Known to the ancients.
Names of Elements.
Gold, .
Silver, .
Iron,
Copper, .
Mercury,
Lead, .
Tin,. .
Sulphur,
Carbon,
Antimony, . . . Described by Basil "Valentine, 1490
Bismuth, . . . Described by Agricola, 1530
Zinc, ..... First noted by Paracelsus, .... 16th centur}r.
Phosphorus, . . Brand, , 1660
Arsenic, . . . ) grant 1733
Hydrogen, . . Cavendish, 1766
Chlorine, . . , Scheele, 1774
Oxygen, . . . Priestly, 1774
Manganese, . . Gahn and Scheele, 1774
Chromium,. . . Vauquelin, 1797
Potassium,
Sodium, .
Sir Humphrey Davy, 1807
Calcium,
Boron, .
Iodine, .... Courtois, 1811
Silicon, .... Berzelius, 1823
Bromine, . . . Ballard, 1826
Aluminium, . . "Wohler, . 1828
Magnesium, . . Bussy, 1829
460
APPENDIX.
TABLE IL
ATOMIC WEIGHTS.*
Hydrogen=1.00.
Aluminium
Al
13.63
Lead
Pb
103.57
Antimony
Sb
129.00
Lithium
Li
6.64
Arsenic
As
75.00
Magnesium
Mg
12.00
Barium.
Ba
68.59
Manganese
Mn
27.57
Bismuth
Bi
208.00
Mercury
Hg
100.05
Boron
B
11.04
Nickel
Ni
29.55
Bromine
Br
79.97
Nitrogen
N
14.00
Calcium
Ca
20.00
Oxygen
O
8.00
Carbon
C
6.00
Phosphorus
P
31.36
Chlorine
Cl
35.46
Platinum
Pt
98.94
Chromium
Cr
26.78
Potassium
K
39.11
Cobalt
Co
29.49
Silicon
Si
14,81
Copper
Cu
31.68
Silver
Ag .
107.97
Fluorine
Fl
19.00
Sodium
Na
23.00
Gold
An
196.67
Strontium
Sr
43.67
Hydrogen
H
1.00
Sulphur
S
16.00
Iodine
I
126.88
Tin
Sw
58.82
Iron
Fe
28.00
Zine
Zn
32.53
* These atomic weights are calculated fro-ni the best and most pre-
cise investigations; some of them have not yet been established by
recent experiment, but are calculated from others eo determined.
FRESEMUS.
APPENDIX.
461
TABLE III.
SPECIFIC GRAVITY OF SOLIDS,
Pure water at 60° F=1.000
Platinum •>"'••'••
20 98
Tin
. . . 7 29
Gold
19 26
Zinc
7 03
13 60
Antimony .
. . 6 70
Lead
, . 11 45
. . 6.65
Silver . . .
. . . 10.50
. . . 6.00
Bismuth. .
9 80
. . 5.80
8 87
Iodine . .
495
Cobalt
8 54
. . . 2 60
Nickel . .
. . . 8.28
. . . 1.86
8 00
Sodum ...
. . . 0 97
Iron .
. -. . 7.80
. . . 0.86
TABLE IV.
SPECIFIC GRAVITY OF LIQUIDS,
Pure water at 60° F=1.000
Mercury 13.596
Bromine . . . 2.79 to 3.19
Sulphuric Acid . . . . 1.800
Nitric Acid 1.515
Ammonia .
Turpentine
Alcohol . .
Ether . .
0.870
0.865
0.800
0.720
TABLE V.
SPECIFIC GRAVITY OF GASES.
Dry air at 60° F=1.000
Chlorine
454
Oxygen
1 109
Nitrous Oxide ....
Carbonic Acid .
.525
525
Carbonic Oxide
Nitrogen .
. . . 0.970
. . . 0 970
Fluorine
296
. . . 0.069
Hydrochloric Ac. gas . .
.261
Ammoniacal gas
. . . 0.589
462
APPENDIX.
TABLE VI.
LINEAR EXPANSION OF SOLIDS ON BEING HEATED FROM 32° TO 212° F.
Zinc (cast)
expands ~z%~%
Iron expands
_,_
Zinc (sheet)
3¥0
Steel (tempered)
a!*
Lead
« sir
Steel (untempered) "
J~2j
Silver
" *i*
Platinum "
TiVT
Copper
" yir
Flint Glass
T2T¥
Gold
***
Black Marble
2"83"1T
TABLE VIL
SPECIFIC HEAT.
Water=1.000
Alcohol 0.660
Ether 0.520
Nitric Acid 0.442
Oil of Turpentine . . . 0.425
Sulphuric Acid .... 0.833
Carbon 0.241
Common Salt 0.225
Lime 0.205
Sulphur 0.202
Glass . ,0.197
Phosphorus 0.187
Iron 0.113
Zinc 0.099
Arsenic 0.081
Tin 0.056
Iodine 0.054
Silver 0.050
Mercury 0.033
Platinum 0.032
Gold , . 0.032
TABLE VIII.
MELTING POINTS OF SOLIDS.
Cast Iron »ne/^ at 3479°
Potassium melts at 154°
Cobalt
2800°
Wax
142°
Silver
2283°
Spermaceti
112°
Gold
2016°
Phosphorus
108°
Copper
Lead
1996°
612°
Tallow
Olive Oil
92°
8G°
Bismuth
497°
Ice
32°
Tin
442°
Oil of Turpentine
—14°
Sulphur
226°
Mercury
— 39°
Newton's Alloy
208°
Liquid Ammonia,
—40°
Sodium
194°
Ether
i
—47°
APPENDIX.
463
TABLE IX.
BOILING POINTS OF LIQUIDS.
Mercury
boils
at
662°
Nitric Acid
boils at
248°
Whale Oil
"
it
630°
Water
' '
212°
Sulphuric Acid
"
««
620°
Alcohol
' '
173°
Sulphur
"
tt
600°
Bromine
< <
116°
Phosphorus
Oil of Turpentine
M
it
tt
551°
312°
Ether
Sulphurous Acid
' '
96°
14°
TABLE X.
COMPOSITION OF HUMAN BLOOD ACCORDING TO LfiCANU.
Water
78.015
Fibrin . . . .
. . 0 210
6509
13.300
Crystallizable fat
0.243
Oily fat
0.131
Salts of the alldlies
0 837
0.210
0 545
100.000
TABLE XL
COMPOSITION OF COW'S MILK.
Water 873.0
Casein, and a little albumen 48.2
Butter 30.0
Sugar of milk 43.9
Phosphate of lime with a little chloride of calcium .... 2.3
Phosphate of iron and magnesia, and a little soda .... 0.9
Chlorides of sodium and potassium 1.7
1000.00
464 APPENDIX.
TABLE XII.
RELATIVE PROPORTIONS OF THE SANGUIGENOUS TO THE RESPIRATORY CONSTI-
TUENTS IN DIFFERENT KINDS OF FOOD.
Sanguigenous.
Respiratory.
Cow's milk contains, for 10
30= -S 8'8 fat and
( 10.4 milk sugar
Human milk
10
40
Horse beans "
10
22
Peas
10
23
Fat mutton "
10
27=11.25 fat
Fat pork
10
30=12.5 "
Beef
10
17=7.08 "
Veal
10
1=0.41 "
Wheat flour "
10
46
Oatmeal
10
50
Rye flour "
10
57
Barley
10
57
Potatoes (white) "
10
86
Potatoes (blue) "
10
115
Rice
10
123
Buckwheat "
10
130
Starch is the principal constituent of respiratory food in the sub-
stances mentioned in the table. When sugar and fat take its place, the
fact is separately indicated, while their equivalent in starch is given
in the principal column for convenience of comparison. The above
table is taken from Liebig's Letters on Chemistry.
TABLE XIIL
PER CENT BY MEASURE OF ALCOHOL IN SPIRITOUS LIQUORS AT 62° F.
Rum contains
72 to 77 per cent.
Cognac "
Whiskey
50 " 54
59
Geneva
50
Port wine "
21 to 23
Sherry
15 " 25
Madeira " "
18 " 22
Malmsey " "
16
Claret " "
9 to 15
Burgundy " "
7 " 13
Rhenish
8 " 13
Moselle
8 " 9
Tokay
9
Champagne "
5 to 15 "
APPENDIX.
465
TABLE XIV.
HOMOLOGOUS SERIES OF ORGANIC ACIDS.
1. Formic ....
CaHaCM 16. Ethalic .
. . . C32H3204
2. Acetic ....
CiHiOi
17. Stearic .
. . . C34H34O4
3. Propiouic . . .
CSH604
18. Bassic .
. . . C3SH3&O4
4. Butyric ....
CsHsOi
19.
5. Valeric ....
CicHicCM
20.
6. Caproic ....
Cl2Hl204
21.
7. Enanthylic . . .
Cl4Hl404
22. Behenic
. . . C44H4404
8. Caprylic ....
CieHieO4
23.
9. Pelargonic . . .
CisHisCh
24.
10. Capric ....
CsoHsoCh
25.
11. Margaritic . . .
C22H2204
26.
12. Laurie ....
C24H2104
27. Cerotic .
. . . C54H3404
13. Cocinic ....
C26H2S04
28.
14. Myristic ....
GssHttOl
29.
15. Benic ....
C3oHscO4
30. Melissic .
. . . CsoHsi04
TABLE XV.
COMPOSITION OF THE ASHES OF COMMON CROPS.
ndian
Corn.
Wheat
Wheat
Straw.
Rye.
Oats.
Pota-
toes.
Tur-
nips.
Hay.
Carbonic acid,
trace.
10-4
Sulphuric acid,
0-5
i-o
i-o
1-5
10-5
7-1
13.6
2-7
Phosphoric acid,
49-2
47-0
31
47-3
43-8
11-3
7-6
6-0
Chlorine, . .
0-3
:race.
0-6
0-3
2-7
3-5
2-6
0-1
2'9
85
2-9
4-9
1*8
13-6
22 -9
Magnesia, . .
17-5
15'9
5-0
10-1
9-9
5-4
5-3
5-7
Potash, . . .
Soda, ....
23-2
3-8
29-5
trace.
7'2
0-3
32-8
4-4
j- 27-2
51-5
trace.
42-0
5-2
18-2
2-3
Silica, ....
0-8
1-3
67-6
0-2
2-7
8-6
7-9
37-9
Iron, ....
0.1
trace.
1-0
0-8
0-4
0-5
1-3
1-7
Charcoal in ash, )
and loss, . )
4'5
2'4
5-7
0-3
0-7
lOO'O
100-0
lOO'O
lOO'O
lOO'O
100-0
100-0
100-0
Lbs. of material }
6000
12500
1000
requir'd to yield >
100 Ibs. of ashes. j
10000
5000
2000
5000
2500
to
13000
to
20000
to
2000
20'
466
APPENDIX.
TABLE XVI.
SOLUBILITY OF SUBSTANCES
KG
NaO
NH40
BaO
SrC
CaO
MgC
AbO
MnO
FeO
NIC
1
1
1
1
1
12
2
2
2
2
2
s
1
1
1
1
1
i2
2
2
2
Cl
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
SO3
1
1
1
3
3
1*8
1
1
1
1
1
NOo
I
1
1
1
1
1
1
1
1
1
1
POs
1
1
1
2
2
2
2
2
2
2
COa
1
1
1
2
2
2
2
2
2
2
CaOs
1
1
1
2
2
2
2
2
2
i 2
BOa
1
1
1
2
2
2
2
2
2
2
2
A
1
1
1
1
1
1
1
1
1
1
1
"T
1
1
1
2
2
2
12
1
i2
i2
AsOs
1
1
1
2
2
2
2
2
2
2
2
AsOa
1
1
1
2
2
2
2
2
CrOs
1
1
1
2
2
2
1
2
1
2
EXPLANATION OF THE TABLE.
To ascertain the solubility or insolubility of a salt from
tbe above table, its acid is sought in the left hand column,
and its base in the upper line. The square, which is in line
APPENDIX.
467
TABLE XVI.— (CONTINUED.)
IN WATER AM) ACIDS.
ZnO
PbO
SnO
SnO
BiOa
CuO
Hg20
HgO
AgC
PtO
SbO
2
2
2
23
2
2
2
2
2
2
s
2
2
2
3
3
2
Cl
1
11
1
1
1
1
2
1
3
1
I
1
2
2
1
2
2
3
SO3
1
2
1
1
1
i2
1
1 2
1
2
NOo
1
1
1
1
1
1
1
1
POs
2
2
2
2
2
2
CO2
2
2
2
2
2
2
2
CaOs
2
2
2
1
2
2
2
2
2
12
BOs
2
2
2
2
2
1
A
1
1
1
1
1
1
12
1
1
1
f
2
2
12
2
1
i2
2
2
1
AsOs
2
2
2
2
2
2
2
AsOs
2
2
2
2
2
2
CrOa
1
2
2
2
2
2
i2
2
2
with both, contains the desired information. The numeral
1, indicates solubility in water ; 2, solubility in either nitric
or hydrochloric acid, and 3, insolubility in either. The
smaller numerals indicate a low degree of solubility.
INDEX.
Acetic Acid, 372.
Acid, Arsenious, 180.
Antidote to, 185.
Marsh's Test for, 181.
Poisonous properties
of, 181.
Boracic, 197.
Carbonic, 189.
Hydrochloric, 210.
Action of, on Metals,
211.
Hydrocyanic, 374.
Hydrofluoric, 212.
Hydrosulphuric, 214.
Muriatic, 210.
Nitric, 173.
Oxalic, 378.
Prussic, 377.
Stearic, 420.
Sulphuric, 162.
Sulphurous, 167.
Stannic, 285.
Tannic, 373.
Acids. Formation of, 136.
Organic, 372.
Properties of, 137.
Affinity, Relation of cohesion and,
277.
Air, Analysis of the, 172
Proportional Composition of
the, 173.
TJnsaturated, 71.
Albumen, Vegetable, 389.
Alcohol, 362.
Aldehyde, Conversion of Alcohol
into, 370.
Alkali, Volatile, 218.
Alkalies, The, 286.
Effects of, on Wood, 353.
Vegetable, 395,
Alkaloids,
Alloys, 272
Alum, 307.
Different kinds of, 308.
Alumina, 292.
Aluminium, 238.
Amalgams, 261.
Ammonia, 216.
Carbonate of, 815.
Nitrate of, 311.
Ammonium, 235.
Oxide of, 290.
Analysis, Chemical, 332.
Organic, 430.
Anastatic printing, 331.
Animal Body, Chemical changes in
the, 424.
Heat, 424.
Tissues, Changes of, 426.
Antimony, 251.
Apparatus for silvering and gild-
ing, 107.
Aqua Regia, 212.
Arsenic, 179.
INDEX.
469
Arsenic, Eaters of Austria, 185.
Marsh's Test for, 181.
Artificial Essences, 382.
Ashes, Effect of, on Soils, 407.
Asphaltum, 386.
Assay of Gold, 269.
Silver, 265.
Atmosphere, Elastic Force of the,
78.
Quantity of vapor in the, 71.
Weight of the, 77.
Atomic Weights, Table of, App.
Atoms and Attraction, 1 1.
Attraction, Chemical, 12.
Distance of, 13.
of Cohesion, 12.
of Gravitation, 12.
B.
Barium, 237.
Barometer Guage. 90.
Baryta, Sulphate of, 307.
Bases, Organic, 395.
Properties of, 137.
Batteries, Different kinds of, 114.
Batten7, Decomposition in the, 112.
Bismuth, 253.
Bleaching, by Oxygen, 147.
Sulphur, 160.
Powder, 298.
Blood, Composition of the, 415.
Changes in the, 424.
Color of the, 425.
Table of the Composition of
the, App.
Transformation of the, 414.
Blowpipe, 227.
Oxhydrogen, 229.
Boiling, 77-80!
Disappearance of Heat in, 81.
Effect of Depth on, 83.
Height on, 83.
Expansion in, 81.
Point, Artificial Change of, 84.
Height measured by, 83.
Bones, 416.
Boracic Acid, 197.
Borates, 323.
Boron, 197.
Bread, Raising of, 393.
Bromine, 158.
Burning Fluid, 380.
46.
of Ice, 47.
C.
Calcium, 237.
Oxide of, 290.
Camphors, 383.
Caoutchouc, 387.
Carbon, 185.
Combustion of, 188.
Carbonates, 313.
Carbonic Acid, 189.
Oxide, 194.
Carburetted Hydrogen, Heavy,222.
Light, 221.
Casein, 389.
Cellars warmed by Ice, 65.
Cement, Hydraulic, 292.
Chamelion Mineral, 326.
Charcoal, Combustion of, in Oxy-
gen, 145.
Decoloring effects of, 188.
Preparation of, 186-349.
Preservative properties of, 187.
Purifying properties of, 187.
Reduction of Ores by, 188.
Cheese, 423.
Chemical Analysis, 332.
Chemistry, Organic, General views
of, 335.
Chloride of Lime, 298.
Sodium, 296.
Chlorides, 294.
Chlorine, 149.
a Disinfectant, 154.
Bleaching by, 153.
Compounds of, with Oxygen,
156.
Relations to Animal Life, 155.
Resemblance to Oxygen, 155
Test for, 301.
Chloroform, 371.
Chromates, 325.
Chromium, 245.
Circulation of Matter, 433.
Clay, 320.
470
INDEX.
Cloth, Incombustible, 352.
Coal, Anthracite, 851.
Oils from, 355.
Cobalt, 245.
Cohesion, 12.
Relation of, and Affinity, 277.
Cold, Definition of, 27.
Extreme, how measured, 59.
Supposed Radiation of, 45.
Water, Lightness of, 55.
Collodion, 356.
Color, Change of, by Touch, 301.
Coloring Matters, 396.
Combustion, Definition of, 145.
under Water, 178.
Composts, 407.
Compound Blowpipe, 229.
Circuit, Decomposition by the,
115.
Galvanic Circuit, 114.
Radicals, 340.
Concave Lens, Action of, 22.
Mirrors, Theory of, 19.
Conducting Power, Simple Test
of, 35.
Copper, 254.
Counterfeiting, Prevention of, 331.
Crystal Forms, Systems of, 281.
Glass, 321.
Crystallization, 208.
Culinary Paradox, 84.
Cupellation, 263.
Cyanides, 374.
Cyanogen, 374.
D.
Daguerreotype, The, 327.
Davy's Safety Lamp, 222.
Decay, Preventives of, 352.
Definite Proportions, Law of, 134.
Dew, 75.
Absence of, on Polished Sur-
faces, 45.
Artificial prevention of, 44.
Formation of, 44.
Point, 74.
how to find the, 74.
Distillation, 97.
Dyeing, 397.
Dyes, Mineral, 399.
E.
Earth, Cooling of the, 43.
Earthen-ware, 322.
Effervescent Drinks, 191.
Elastic Force of Vapors, 89
Electric Light, 111.
Electricity and Magnetism, 99.
Conduction of, 103.
Decomposition of water by.
105.
Frictional, 102.
Galvanic, 103.
Quantity of, in Matter, 104.
Theory of, 102.
Electrodes, 103.
Elements, Electrical Relations"of
138.
Number of, 11.
Table of, App.
Empyreumatic Oils, 382.
Enamel, 322.
Engine, The Steam, 91.
Equivalents, Chemical, 134
Table of, App.
Essences, Artificial, 382.
Essentials Oils, 379.
Etching on Glass, 213.
Ether, Conversion of Alcohol into,
368.
Ethyl, Production of, 369.
Evaporation, Economy in, 97.
Effect of Wind on, 70.
Freezing by, 68.
Protection from Heat by, 68.
Expansion, 50.
Fracture of Glass Vessels by,
53.
Law of, for Gases, 57.
Lifting Walls by, 52.
of Cold Water by Cold, 54.
Gases, 56.
Liquids, 54-56.
Solids, 51.
Wood and Marble, 53.
INfJEX.
471
F.
Fats, Composition of, 419.
Separation of, in Oil, 419.
Tallow and
Lard, 420.
Fermentation, 391.
Ferrocyanides, 376.
Fibre, Woody, 349.
Filtration, 207.
Fire by Compression, 50.
on Water, 36.
Proof Safes, 35.
Flame, 225.
Effect of, on Metals, 226.
Flesh, 417.
Fluorides, 302.
Fluorine, 158.
Fogs, 72.
Food and Temperature, Kelations
of, 426.
Proportions of, 429.
Transformation of the, 414.
Varieties of, 428.
Freezing, 64.
by Evaporation, 68.
Mixtures, 63.
Fusel Oil, 372.
O.
Galvanic Coil, Motion of a sus-
pended, 120.
Polarity of, imparted to
Metals. 122.
Polarity of the, 119.
The, a magnetic needle,
121.
Coils, Mutual Action of, 121.
Current, Heating Effects of
the, 111.
Magnetic Effects of the,
119.
Galvanism, Discovery of, 127.
Physiological Effects of, 126.
Gas from Wood, 225.
Illuminating, 223-349.
Gastric Juice, The, 414.
Gelatine, 418.
ermination, 345.
Gilding, 270.
Galvanic, 107.
lass, Colored, 322.
Crystal, 321.
cut by Hot Wire, 53.
Etching on, 213.
Soluble, 320.
Staining, 294.
Window, 320.
Glauber's Salt, 306.
Glycerine, 420.
Gold, 267.
Gravitation, 12.
Green, Chrome, 326.
Mineral, 400.
Guano, 407.
Gum from Wood, 357.
Resins, 387.
Gun Cotton, 355.
Gunpowder, 311.
Gutta Percha, 388.
Gypsum, 305.
II.
Heat, Absorption of, 42.
Analysis of, 46.
Animal, 424.
Capacity for, 49.
Changes effected by, 48.
Communication of, 30.
Conduction of, 30.
Convection of, 37.
Disappearance of, in Boiling,
81.
Melting, 62.
Vapors, 67.
Extreme, how measured, 60.
Latent, 65.
Nature of, 25.
of Chemical Action and Elec-
tricity, 29.
the Fixed Stars, 29.
Protection from, by evapora-
tion, 68.
Quantity of, given out by tha
Sun, 28.
Radiation of, 39.
472
INDEX.
Heat, Rays of, 45.
Effect of different, 47.
Reflection of, 41.
Refraction of, 45.
Relation of, to Density, 49.
Specific, 48.
the Ocean a Reservoir of, 50.
Theories of, 25.
Transmission of, 41.
Heavy Carburetted Hydrogen,
222.
Hides, Tanning, 418.
Homologous Series, 341.
Table of the, of
Organic Acids,
App.
Humus, Production of, 351.
Hydrates, 286.
Hydraulic Cement, 292.
Hydrochloric Acid, 210.
Hydrocyanic Acid, 374.
Hydrofluoric Acid, 212.
Hydrogen, 197.
Phosphuretted, 219.
Sulphuretted, 214.
I.
Ice in the Tropics, 43.
Ignition by Lime, 291.
Illuminating Gas, 223.
Incrustations in Boilers, 316.
Indigo, 396.
Induction, Magnetic, without Con-
tact, 101.
Ink, Writing, 373.
Intensity of Electricity, Meaning
of, 115
Iodine, 156.
Iron, 240.
Combustion of, in Oxygen, 143.
Isomorphism, 284.
EN
Lamp Black, Preparation of, 187.
Latent Heat, Proof that Boiling is
effected by, 96.
Latent Heat, Quantity of, in Steam,
96.
Sum of, and Sensible Heat
always the same, 96.
Laughing Gas, 311.
Lead, 256.
Chromate of, 325.
Light, 15.
Analysis of, 22.
Chemical Action of, 15-329.
Laws of, 17.
Medium, Definition of, 17.
Ray, Definition of, 17.
Reflection of, 18.
Refraction of, 20.
Theories of, 15.
Light Carburetted Hydrogen, 221.
Lime, Action of, in Soils, 405.
Ignition by, 291.
Nitrate of, 309.
Sulphate of, 305.
Liniments, 422.
Liquefaction, 61.
Liquids, Conversion of vapors into,
95.
Nonconductors of Heat, 36.
Logwood, 397.
Dyeing with, 399.
Lunar Caustic, 312.
Madder, 397.
Magnesium, 237.
Magnet, Artificial, 99.
Magnetic Induction without Con-
tact, 101.
Needle, 99.
Telegraph, 124.
Magnets, Attraction of, for each
other, 100.
Native, 99.
Magnetism, Electrical Theory of,
126.
Induced, 100.
Mahomet's Coffin, 119.
Manganates, 326.
Manganese, 239.
Marble, Artificial, 317.
Marsh's Test for Arsenic, 181.
INDEX.
473
Matches, Friction, 178.
Mercury, 259.
Quantity of, the Air can Sus
tain, 80.
Metals, 231.
Classification of, 231.
Deposition of, by Electricity,
106.
Effect of flame on, 106.
Milk, 422.
Solid, 423.
Table of the Composition of,
Cow's, A pp.
Human, App.
Mineral Dyes, 399.
Moisture, Deposition of, 70.
Molasses, 361.
Mordants, 398.
Multiple Proportions, Laws of, 134.
Muriatic Acid, 210.
Effect of, on Wood, 354.
Nickel, 246.
Nitrate of Silver, 312.
Nitrates, 309.
Nitre, 310.
Nitric Acid, 173.
Effects of, on Wood, 352.
Nitrogen, 169.
Nutrition, Vegetable, 346.
O.
Oil of Vitriol, Manufacture of, 163.
Oils, Empyreumatic, 382.
Essential, 379.
from Coal, 355.
Olefiant Gas, Conversion of Alco-
hol into, 369.
Organic Acids, 372.
Analysis, 430.
Bases, 395.
Chemistry, General Views of,
335.
Oxalic Acid, 378.
Oxides, 285
Oxides, Formation of, 136.
Names of, 135.
reduced by Carbonic Oxide,
195.
Uses of, 293.
Oxygen, 141.
a Purveyor for Plants, 147.
Bleaching by, 147.
Compounds of, with Chlorine,
156.
Oxhydrogen Blowpipe, 229.
Ozone, 148.
P.
Peat, 350.
Petroleum, 386.
Phosphates, 317.
Phosphorescence, 177.
Phosphorus, 176.
Combustion of, by Nitric Acid,
176.
Combustion of, in Oxygen, 144.
Phosphuretted Hydrogen, 219.
Photographs, 329.
Plants, Constituents of, 348.
Relation of, to the Soil, 402.
Plaster, Aluminated, 306.
of Paris, 305.
Platinum, 271.
Porcelain Painting, 323.
Potassa, 287.
Carbonate of, 314.
Nitrate of, 310.
Potassium, 233.
Cyanide of, 375.
Precipitation, 207-275.
Pressure, Actual, in different En-
gines, 90.
of the Atmosphere, 79.
The Exact Relation of Temper-
ature to, 88.
Printing, Anastatic, 331.
Calico, 400.
Prism, construction of, 21.
Effect of, on Rays, 21.
Prussic Acid, 377.
Putrefaction, 390.
474
INDEX.
Quantity of Electricity, Meaning
of, 115.
R.
Radiation of Heat, 39.
Color not effected by, 40.
Polish unfavorable to, 40.
Proportion of, to Temperature;
39.
Radicals, Compound, 340.
Rays, Heat and Chemical, 45.
Refraction of Heat, 45.
Light, 20. ^
Refrigerators, Construction of, 34.
Resins, 383.
Gum, 387.
Respiration, 425.
Roots, Office of the, 347.
Rosin Oil, 386.
Soap, 385.
S.
Safety Lamp, Davy's, 222.
Sal- Ammoniac, 218.
Volatile, 315.
Salt, Common, 296.
Decomposition of a, by Gal-
vanism, 117.
Glauber's, 306.
Saltpetre, 310.
Salts, 274.
Formation of, 136.
Names of, 135.
Sealing Wax, 385.
Shot, Manufacture of, 259.
Silicates, 319.
Silicon, 196.
Silver, 262.
Assay, 265.
Nitrate of, 312.
obtained from Lead, 263.
Silvering, Galvanic, 107.
Sizing for Paper, 875.
Skin," Tendons and Ligiments, 417.
Soaps, 421.
Properties of, 422.
Soda, Carbonate of, 314.
Sulphate of, 306.
Sodium, 235.
Chloride of, 296.
Soils, 402.
Soldering, 324.
Soluble Glass, 320.
Solution, 206-274.
Effect of, on Chemical Affinity,
138.
Spirituous Liquors, 366.
Stalactites, 317.
Stalagmites, 317.
Starch, 357.
Starvation, 427.
Steam Boilers, 86.
Elastic Force of, 87.
Engine, 91.
Guages, 90.
Heating Houses by, 95.
• Safety Valve, 91.
Water Heated by, 95.
Stearic Acid. 420.
Steel, 243.
Permanent Magnetism of, 123.
Tempering, 244.
Strontium, 237.
Substitution, Equivalent, 339.
Substitutions, 343.
Sugar, Boiling in Vacuo, 85.
Cane, 360.
Grape, 359.
from Starch, 358.
Wood, 356.
Manufacturing, Use of Sul-
phurous Acid
in, 159.
Sulphates, 305.
Sulphur, 159.
Liver of, 303.
Milk of, 304.
Sulphurets, 302.
Sulphuretted Hydrogen, 214.
Sulphuric Acid, 16.2.
Effect of, on Wood, 352.
Sulphurous Acid, 167.
Superphosphate of lime, 318-411.
INDEX.
475
Symbols, Calculation of Weights
from, 133.
Explanation of, 132.
T.
Tannic Acid, 373.
Tanning, Hides, 418.
Tar, Wood, 353.
Tartar, 367.
Tea Kettle, Singing of the, 86.
Temperature and Food, Relations
of, 426.
Equilibrium of, 42.
The exact Relation of Pres-
sure to, 88.
Thermometers, Graduation of, 58.
Manufacture of, 57.
The Air, 60.
Tin, 248.
Tissues, Repair of the, 428.
Types, Chemical, 339.
T.
Vaporization, 66.
Vapor, Capacity of the Air for, 75.
Quantity of, in the Atmos-
phere, 69.
Quantity of water the Air
may contain as, 69.
Relations of Air and, 69.
Vapors, Conversion of Liquids in-
to, 95.
Density of, 66.
depends on Tem-
perature, 67.
Elasticity of, 66.
Formation of, 66.
Transparent, 66.
Varnishes, 384.
Vegetable Chemistry, 345.
Vinegar, Conversion of Alcohol
into, 370.
Process of Manufacture, 371.
Wood, 353.
Voltaic Pile, 118.
Vulcanized Rubber, 387.
W.
"Water, Action of, on Lead, 257.
Affinity of Potassa for, 288.
Capacity of Air for, increased
by Heat, 70.
Chemical Combinations of,
208.
Decomposition of, by Electri-
city, 105-115.
Hammer, 85.
heated by Steam, 95.
Proof of the Composition of,
203-204.
Quantity of, the Air may con-
tain as Vapor, 69.
Quantity of, the Pressure of
the Air will Sustain,
79.
Sea, 297.
Theory of the Decomposition
of, 105. \
Welding Iron, 243.
White Rotten Wood, 351.
Window Glass, 320.
Wines, 366.
Wood, 349.
Charred by Sulphuric Acid,
167.
Conversion into Gum, 357.
Sugar, 356.
Y.
Yeast, 391,
Powders, 393.
Yellow, Chrome, 325-400.
Z.
Zinc, 246.
476 APPARATUS AND MATERIALS.
LIST OP CHEMICALS AND APPARATUS REQUIRED FOR THE EX-
PERIMENTS DESCRIBED IN THIS WORK.
1 lb. Black Oxide of Manganese
J " Bleaching Powders.
£ " Chlorate of Potassa.
J « Alum.
£ " Sulphur.
J " Common Caustic Potash, in Sticks.
I " Acetate of Lead, (Sugar of Lead.)
1 " Sulphate of Copper, (Blue Vitriol.)
J " Carbonate of Ammonia, (Sal Volatile.)
2 oz. Bichromate of Potash.
2 " Bone Black.
2 " Sulphuret of Iron.
2 " Nitrate of Potash, (Salt Petre.)
" Chloride of Ammonium, (Sal Ammoniac.)
" Yellow Prussiate of Potash.
" Cyanide of Potassium.
14 Oxalic Acid.
" Ground Nut Galls.
1 " Phosphorus.
1 " Fluor Spar.
1 " Borax.
1 " Chloride of Barium.
1 " Chloride of Strontium.
1 " Chloride of Mercury, (Corrosive Sublimate.)
1 " Beeswax.
1 " Metallic Antimony
1 " Block Tin.
1 " Bismuth.
2 «« Mercury, (Quicksilver.)
1 " Arsenious Acid, (Ratsbane.)
APPARATUS AND MATERIALS. 477
\ oz. Tartar Emetic.
\ " Iodide of Potassium.
J " Iodine.
£ " Potassium.
J " Solution of Chloride of Platinum.
1 Glass, (4 oz.) Spirit Lamp.
Fine platinum foil and wire.
1 doz. assorted test-tubes.
^ sheet blue Litmus Paper.
\ " red Litmus Paper.
Fine Iron Wire.
* Sheet Zinc.
* Sheet Copper.
* Sulphuric Acid, (Oil of Vitriol.)
* Hydrochloric Acid, (Muriatic Acid.)
* Nitric Acid, (aqua fortis.)
* Alcohol.
* Ether.
* Clay Pipes and Vials.
* Bowls, Tumblers, &c.
* Not contained in the box of apparatus and materials put up to
accompany this work.
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