<h2><SPAN name="CHAPTER_V" id="CHAPTER_V"></SPAN>CHAPTER V.</h2>
<h3>THEORY OF ELECTRICITY.</h3>
<p>In the series of chapters on Heat (Vol. II)
and in the chapter on Magnetism the word
molecule was frequently used synonymously
with atom. In chemistry a distinction is
made, and as we can better explain the theory,
at least, of electricity by keeping this distinction
in mind we will refer to it here.</p>
<p>It has been stated that there are between
sixty and seventy elementary substances. An
elementary substance cannot be destroyed as
such. It can be united with other elements
and form chemical compounds of almost endless
variety. The smallest particle of an elementary
substance is called in chemistry an
atom. The smallest particle of a compound
substance is called a molecule. The atom is
the unit of the element, and the molecule is
the unit of the compound as such. It follows,
then, that there are as many different kinds of
atoms as there are elements, and as many
different kinds of molecules as there are compounds.
If the elements have a molecular
Structure then two or more atoms of the same<span class="pagenum"><SPAN name="Page_40" id="Page_40"></SPAN></span>
kind must combine to make a molecule of an
elementary substance. Two atoms of hydrogen
combine with one of oxygen to form one
molecule of water. It cannot exist as water in
any smaller quantity. If we subdivide it, it no
longer exists as water, but as the original gases
from which it was compounded.</p>
<p>We have shown in the series on Sound, Heat
and Light that they are all modes of motion.
Sound is transmitted in longitudinal waves
through air and other material substance as
vibration. Heat is a motion of the ultimate
particles or atoms of matter, and Light is a
motion of the luminiferous ether transmitted
in waves that are transverse. Electricity is
also undoubtedly a mode of motion related in
a peculiar way to the atoms of the conductor.</p>
<p>Notice that there is a difference between conduction
and radiation. The former transmits
energy by a transference of motion from atom
to atom or molecule to molecule within the
body, while the latter does it by a vibration
of the ether outside—as light, radiant heat,
and electromagnetic lines of force.</p>
<p>For the benefit of those persons who have
not read Vol. II, where the nature of ether
is discussed somewhat, let us refer to it
here, as it plays an important part in the explanation
of electrical phenomena. Ether is a
tenuous and highly elastic substance that fills
all interstellar and interatomic space. It has<span class="pagenum"><SPAN name="Page_41" id="Page_41"></SPAN></span>
few of the qualities of ordinary matter. It is
continuous and has no molecular structure. It
offers no perceptible resistance, and the closest-grained
substances of ordinary matter are
more open to the ether than a coarse sieve is
to the finest flour. It fills all space, and, like
eternity, it has no limits. Some physicists
suppose—and there is much plausibility in the
supposition—that the ether is the one substance
out of which all forms of matter come.
That the atoms of matter are vortices or little
whirlpools in the ether; and that rigidity and
other qualities of matter all arise in the ether
from different degrees or kinds of motion.</p>
<p>Electricity is not a fluid, or any form of material
substance, but a form of energy. Energy
is expressed in different ways, and, while as
energy it is one and the same, we call it by
different names—as heat energy, chemical
energy, electrical energy, and so on. They will
all do work, and in that respect are alike. One
difficulty in explaining electrical phenomena is
the nomenclature that the science is loaded
down with. All the old names were adopted
when electricity was regarded as a fluid, hence
the word "current." It is spoken of as "flowing"
when it does not flow any more than light
flows.</p>
<p>If a man wants to write a treatise on electricity—outside
of the mere phenomena and
applications—and wants to make a large book<span class="pagenum"><SPAN name="Page_42" id="Page_42"></SPAN></span>
of it, he would better tell what he does not
know about it, for in that way he can make a
volume of almost any size. But if he wants
to tell what it really is, and what he really
knows it is, a primer will be large enough.
This much we know—that it is one of many
expressions of energy.</p>
<p>Chemistry teaches that heat is directly related
to the atoms of matter. Atoms of different
substances differ greatly in weight. For
instance, the hydrogen atom is the unit of
atomic weight, because it is the lightest of all
of them. Taking the hydrogen atom as the
unit, in round numbers the iron atom weighs
as much as 56 atoms of hydrogen, copper a
little over 63, silver 108, gold 197. Heat acts
upon matter according to the number of atoms
in a given space, and not as its weight. Knowing
the relative weights of the atoms of the
different metals named, it would be possible
to determine by weight the dimensions of
different pieces of metal so that they will contain
an equal number of atoms. If we take
pieces of iron, copper, silver and gold, each of
such weight as that all the pieces will contain
the same number of atoms, and subject them
to heat till all are raised to the same temperature,
it will be found that they have all absorbed
practically the same quantity of heat
without regard to the different weights of matter.
It will be observed that the piece of sil<span class="pagenum"><SPAN name="Page_43" id="Page_43"></SPAN></span>ver,
for instance, will have to weigh nearly
twice as much as the iron in order to contain
the same number of atoms, but it will absorb
the same amount of heat as the piece of iron
containing the same number of atoms, if both
are raised to the same temperature. In view
of the above fact it seems that heat acts especially
upon the atoms of matter and is a
peculiar form of atomic motion. Heat is one
kind of motion of the atoms, while electricity
may be another form of motion of the same.
The two motions may be carried on together.
The earth has a compound motion. It revolves
upon its axis once in twenty-four hours,
and it also revolves around the sun once each
year. So you see that there are different kinds
of motion that may be communicated to the
same body—all producing different results.</p>
<p>The motion of the individual atom as heat
may be, and is, as rapid as light itself when
the temperature is sufficiently high, but it does
not travel along a conductor rapidly as the
electro-atomic motion will. If we apply heat
to the end of a metal rod it will travel slowly
along the rod. But if we make the rod a conductor
of electricity it travels from atom to
atom with a speed nearer that of the light ray
through the ether. Some modern writers have
attempted to explain all the phenomena of
electricity as having their origin in a certain
play of forces upon the ether, and there is no<span class="pagenum"><SPAN name="Page_44" id="Page_44"></SPAN></span>
doubt but that the ether plays an important
part in all electrical phenomena as a medium
through which energy is transferred; but
ether-waves that are set in motion by the electrical
excitation of ordinary matter are no
more electricity than the ether-waves set up
by the sun in the cold regions of space are heat.
They become heat only when they strike matter.
Heat, <i>as such</i>, begins and ends in matter;—so
(I believe) does electricity.</p>
<p>Do not be discouraged with these feeble attempts
to explain the theory of electricity. All
I even hope to do is to establish in your minds
this fundamental thought, to wit, that there is
really but one Energy, and that it is always
expressed by some form of motion or the ability
to create motion. Motions differ, and
hence are called by different names.</p>
<p>If I should set an emery-wheel to revolving
and hold a piece of steel against it the piece
of steel would become heated and incandescent
particles would fly off, making a brilliant display
of fireworks. The heat that has been developed
is the measure of the mechanical
energy that I have used against the emery-wheel.
Now, let us substitute for the emery-wheel
another wheel of the same size made of
vulcanized rubber, glass or resin. I set it to
revolving at the same speed, and instead of
the piece of steel, I now hold a silk handkerchief
or a catskin against the wheel with the<span class="pagenum"><SPAN name="Page_45" id="Page_45"></SPAN></span>
same force that I did the steel. If now I
provide a Leyden jar and some points to
gather up the electricity that will be produced
(instead of the heat generated in the other
case), it would be found that the energy developed
in the one case would exactly balance
that of the other, if it were all gathered up and
put into work. The electricity stored in the
jar is in a state of strain, like a bent bow, and
will recoil, when it has a chance, with a power
commensurate with the time it has been storing
and the amount of energy used in pressing
against the wheel.</p>
<p>If now I connect my two hands, one with the
inside and the other with the outside of the
jar, this stored energy will strike me with a
force equal to all the energy I have previously
expended in pressing against the wheel, minus
the loss in heat. If I did it for a long enough
time this electrical spring would be wound up
to such a tension that the recoil would destroy
life if one put himself in the path of its discharge.
If all the heat in the first case were
gathered up and made to bend a stiff spring,
and one should put himself in its way when
released, this mechanical spring would strike
with the same power that the electrical spring
did when the Leyden jar was discharged.
This statement assumes that all the energy in
the second experiment was stored as electricity
in the jar. You will be able to see<span class="pagenum"><SPAN name="Page_46" id="Page_46"></SPAN></span>
from the above illustration that heat, electrical
energy, and mechanical energy are really
the same. Then you ask, how do they differ?
Simply in their phenomena—their outward
manifestations.</p>
<p>While there is much that we cannot know
about any of the phenomena of nature, it is
a great step in advance if we can establish a
close relationship between them. It helps to
free electricity from many vagaries that exist
in the minds of most people regarding it;
vagaries that in ignorant minds amount to
superstition. While it possesses wonderful
powers, they give it attributes that it does not
possess. Not long ago a favorite headline of
the medical electrician's advertisement was
"Electricity Is Life," and it was a common
thing to see street-venders dealing out this
"life" in shocking quantities to the innocent
multitudes—ten cents' worth in as many
seconds.</p>
<p>Science divides electricity into two kinds—static
and dynamic. Static comes from a
Greek word, meaning to stand, and refers to
electricity as a stationary charge. Dynamic is
from the Greek word meaning power, and refers
to electricity in motion. When Franklin made
his celebrated kite experiment, the electricity
came down the string, and from the key on
the end of the string he stored it in a Leyden
jar. While the electricity was moving down<span class="pagenum"><SPAN name="Page_47" id="Page_47"></SPAN></span>
the string it was dynamic, but as soon as it
was stored in the Leyden jar it became static.
Current electricity is dynamic. A closed telegraphic
circuit is charged dynamically, while
the prime conductor of a frictional electric machine
is charged statically. The distinction
is arbitrary and in a sense a misnomer. When
we rub a piece of hard rubber with a catskin
it is statically charged because the substances
are what are called non-conductors,
and the charge cannot be conducted readily
away. All substances are divided into two
classes, to wit, conductors or non-electrics, and
non-conductors or electrics, more commonly
called dielectrics. These, however, are relative
terms, as no substance is either a perfect conductor
or a perfect non-conductor.</p>
<p>The metals, beginning with silver as the
best, are conductors. Ebonite, paraffine, shellac,
etc., are insulators, or very poor conductors.
The best conductors offer some resistance to
the passage of the current and the best insulators
conduct to some extent. If we make a
comparison of electric conductors we find that
the metals that conduct heat best also conduct
electricity best. This, it seems to me, is a confirmation
of the atomic theory of electricity
so far as it means anything. If a good conductor,
as silver, is subjected to intense cold
by putting it into liquid air, its conductivity
is greatly increased. It is well known that<span class="pagenum"><SPAN name="Page_48" id="Page_48"></SPAN></span>
heating a conductor ordinarily diminishes its
power to conduct electricity. This shows that,
in order that electrical motion of the atom
may have free play, the heat motion must be
suppressed.</p>
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