GIFT OF
//if.
ELECTRICITY AND ITS SOURCE
ELECTRICITY
AND ITS SOURCE
BY
COLONEL W. F. BADGLEY
INDIAN STAFF CORPS, SURVEY OF INDIA, RETIRED
A.I.C.E., F.R.G.S., F.R.M.S.
MEMBER ASTRONOMICAL SOCIETY OF FRANCE
GUILDFORD
BILLING^& SONS, LTD.
LONDON PRINTING WORKS
1916
All rights reserved
CONTENTS
CHAPTER PAGE
I. OBJECT OF THE BOOK 1
H. THE VOLTAIC CELL: VOLTAIC ELECTRICITY 3
IH. CHEMICAL ACTION IN THE CELL: VOLTAIC ELECTRICITY - 11
IV. THEORIES OF ELECTROLYSIS, AND ACTION AT THE ANODE'.
VOLTAIC ELECTRICITY ------ 20
V. THE CURRENT AND ITS EFFECTS: VOLTAIC ELECTRICITY- 31
VI. THE VOLTAIC PILE AND ELECTRODEPOSITION: VOLTAIC
ELECTRICITY - - - - - --39
VII. THE ELECTRICAL MACHINE: STATIC ELECTRICITY - - 46
VIII. THE CHEMICAL ACTION: STATIC ELECTRICITY 54
IX. ACTION OF HEAT AND CURRENT ON JUNCTIONS: THERMO-
ELECTRICITY ------- 62
x. CHEMICAL ACTION: THERMOELECTRICITY 69
XI. CONDUCTION THROUGH GASES ----- 77
XH. CONDUCTION BY LIQUIDS AND SOLIDS - - - 87
XIII. ELECTROLYTIC SURFACE CONDUCTION 94
XIV. NONCONDUCTORS - 102
XV. ELECTRICAL RESISTANCE IS THE OPPOSITION BY CON-
DUCTORS TO THE ELECTRIC CURRENT - - - 110
XVI. ELECTRIC WIND AND GLOW DISCHARGE - - - 119
XVII. BRUSH AND SPARK DISCHARGES ----- 128
XVUI. CHEMICAL ACTION OF DISCHARGE - 135
XIX. ACTION OF INFLUENCE ____-- 144
XX. INFLUENCE IS AN JETHER WAVE ----- 151
XXI. INFLUENCE AND INDUCTION - - 15(5
XXII. THE ACTION OF INDUCTION 162
XXIII. THE PRODUCTION OF INDUCTION ----- 171
XXIV. ELECTROLYSIS NOT STORAGE 179
C STORAGE
337738
vi CONTENTS
CHAPTER PAOB
XXV. CONVECTION AN INTERRUPTED CONDUCTION - - 187
XXVI. ELECTRICITY CAUSES A MOTION OF MATERIAL - - 193
XXVII. FLUID IS THE CONDUCTOR ON SOLID CONDUCTORS I
ELECTRICITY - 206
XXVIH. INFLUENCE: ELECTRICITY - - - - - -212
XXIX. TWO ELECTRICITIES ------- 220
XXX. THE RAY DESCRIBED ------- 230
XXXI. HERTZIAN RAYS 239
XXXII. RONTGEN AND OTHER RAYS - - 246
XXXIH. ATMOSPHERIC ELECTRICITY - 256
xxxiv. DESCRIPTIVE: THE AURORA - 264
xxxv. DEDUCTIONS: THE AURORA - - - - - 275
XXXVI. NATURAL GLOW DISCHARGE: ST. ELMO'S FIRE - - 281
XXX VII. NATURAL GLOW DISCHARGE: FIREBALLS - 287
xxxvin. PRODUCTION: LIGHTNING ------ 296
xxxix. EFFECT: LIGHTNING ------- 395
XL. INSTANCES AND DEDUCTIONS: ANIMAL ELECTRICITY - 311
XLI. COMETS: COMETS' TAILS - - - - 317
XLII. COMETS' TAILS- ----- 325
XLIII. APPENDIX - -- 336
INTRODUCTORY
CHAPTER I
OBJECT OF THE BOOK
A WHAT is electricity ? The object of the book is to answer
J ' this question if we can.
One or two books have already been written with this
avowed object, but have got no further than to dogmatize
on a pet theory supported by some effects produced by
electricity.
As electricity is only known by its effects, it is right to
describe its actions, and the mistake made by the authors
of those books was, the working from an uncertain top of
theory downwards, instead of from a secure base of facts
upwards.
It is only by allowing ourselves to be led by facts that
we can come to a true decision, and we are certainly more
likely to do so if we enter on the subject with our minds
quite free from any prejudices, and judge entirely by the
-evidence given by experiment. We must, in fact, act in
the manner in which juries are supposed to act, and look
upon theories as special pleadings tending to divert our
minds from the true verdict. " Enter if you can without
preconceived notions, listen to nothing that the facts cannot
establish, and deny yourself the luxury of any theory at all.
Then you may succeed where authority fails/' This was
written with reference to investigation of crime, but it is
equally applicable to any investigation. Charles Darwin
is usually supposed to have begun his work with his theory,
1
2 J ;/> ; I NTROPVCTOR Y
but it was not so, for he himself says that he started " with-
out any theory and collected facts in a wholesale way/'
and we cannot do better than follow his very notable ex-
ample.
For clearness of examination we must group the actions of
electricity, so we will divide the subject into sections to
be studied separately, and we will not come to any decision
on the main question till we have gone through all the
sections. In one or two places the writer has forgotten
this good intention, and has made deductions that further
consideration has shown to be wrong : they have been left
to show the unwisdom of premature conclusion, and must
not be taken as the final word.
Confirmatory extracts from the works of scientists are
given to show that the author is supported in what he says
by well-known men, and these extracts are marked " thus/'
The author begs his readers to read the text as though
it was a series oi lectures to an experimenting class in which
he and they are co-students. This will allow of a little
more freedom and simplicity of speech, with less of that
dry-as-dustiness and stilted tone so constantly found in
scientific works.
Neither magnetism nor electrodynamics will form any
part of our study ; therefore, as these are used in nearly all
practical work, the book is not likely to interest the man
whose interest in science is merely pecuniary.
Current is only a part of electricity, but current is so
commonly used for electricity that probably it will be often
found used in that sense in this book.
VOLTAIC ELECTRICITY
CHAPTER II
THE VOLTAIC CELL
WE will begin our study of electricity by examining the
phenomenon of its production in the voltaic cell. When
we have finished with this, we will go on to other modes of
production, and we will keep each branch of the subject
separate, and pick out from each its reliable results, and
when we have finished with all, we will assemble our results
and see whether they may form a basis for a sensible and
incontrovertible explanation.
To understand the principle of the voltaic cell it will be
best to take it, to begin with, in its simplest form, which is
a vessel, three-fourths full of acidulated water, in which
two metal plates are suspended separately and facing one
another: each plate has a wire soldered to its upper end,
and the junctions of the wires and plates, and the wires for
an inch or two above the junctions, are coated with shellac
varnish to protect them from the action of the acid in the
water.
The plates must be of dissimilar metals, for the action of
the cell depends on the chemical activity of the one metal,
and the resistance to change of the other, and the greater
the difference the stronger the cell. This difference is
named difference of potential, and the more potent or power-
ful metal is the one that more weakly dissolves away.
It is easy to show that two dissimilar metals are required,
for two similar pieces say of zinc arranged in the cell, in
place of the usual pieces of zinc and copper, will be equally
corroded, but will give no current: and neither will two
3
4 VOLTAIC ELECTRICITY
pieces of any metal that is not acted on such as platinum
give any current.
When a piece of common commercial zinc is put in water,
mixed with some sulphuric acid, we see that the zinc be-
comes corroded and that bubbles of gas are set free at its
surfaces; and this gas, if collected and examined, is found
to be hydrogen. This hydrogen must come from the water,
as that is the only substance present in which there is any
of it. Chemically, the substances we have used are zinc,
sulphuric acid, which is composed of one part of sulphur and
three of oxygen, and water composed of two parts of
hydrogen and one of oxygen. Or in chemical symbols,
Zn + S0 3 + H 2 O. The sulphuric acid and the oxygen of the
water attack the zinc and produce sulphate of zinc, and the
hydrogen goes free. Or in symbols the result is ZnS0 4 +
H 2 . It is a somewhat slow process, and some chemists
say that the zinc is attacked by the acid because of an
electrical action set up by minute bits of impurities, mostly
iron, scattered through it, and that perfectly pure zinc
would not be corroded, in which case there would be no
change and no hydrogen set free.
However this may be, as perfectly pure zinc is difficult
to get, it is the general practice to prevent this local action
by amalgamating the zinc, which is done in the following
way. After washing the zinc with dilute sulphuric acid,
a few drops of mercury are rubbed on its surfaces with a
bit of rag tied to a stick : the mercury dissolves the surfaces:
and if the amalgamated zinc is now put into the acid and
water, there is no action until the wires from the zinc and
copper are joined: the zinc is then again corroded, and as
fast as it is dissolved away in the amalgamated surface,
the mercury dissolves a fresh layer of the plate. The im-
purities either dissolve or fall to the bottom.
The reason why the zinc is preserved by the amalgamation
in one instance and not in the other, is that the chemical
VOLTAIC ELECTRICITY 5
union of the zinc and mercury of the amalgamated plate
is strong enough to resist the action of the sulphuric acid
and oxygen of the water, until these are assisted by some
force that begins to act on joining the circuit of the wires.
To show better the effect of completing the circuit by
joining the wires, we will use ordinary unamalgamated zinc.
Putting the zinc in the cell, we see the hydrogen bubbles
rising from its surface. Now if we put in a copper plate
and join the wire from the zinc to the wire from the copper,
we see that there is some immediate change: that the zinc
is more quickly corroded, and that the hydrogen instead
of coming from its surface, comes from the surface of the
copper. We remove the plates and examine them: the
zinc is corroded and the copper unchanged.
It is quite clear from this, that in addition to the chemical
union of the zinc, acid, and oxygen, and the consequent
decomposition of the water, which would ordinarily occur,
that the joining of the wires produces a movement that
traverses the water between the plates, and that by this move-
ment the hydrogen of the water is liberated at the copper.
When we bring the two wires together, we see a small
bright spark at the point of junction, and if instead of bring-
ing the two wires directly together we join them with a
short bit of fine platinum wire, the wire will become hot,
and if very fine may become white hot and consume away.
Evidently the action in the cell causes some power to
traverse the wires as well as the water.
This power has been found to be electricity.
In the voltaic cell it is an electricity which in its action
resembles a broad and placid river whose current is ample
but mild: in fact, so different from the electricity of the
lightning, or of the electrical machine, that at first it was
thought to be a different power: but their only difference
is in what is called their electromotive force. The current
of the electrical machine has little volume but much of this
6 VOLTAIC ELECTRICITY
force, and a rapid succession of long sparks can be kept
up by working the machine: while the current of the cell
has volume but little force, and Mr. DelaRue, with a battery
of eleven thousand cells, could only obtain from it a spark
somewhat less than two-thirds of an inch long.
The current of electricity circulates through the cell and
the wires, and it has, until lately, been accepted that it
flows from the zinc, through the fluid in the cell to the copper,
and thence by the wires to the zinc again. At present
there is an idea that the current flows in the opposite
direction: and also it has been supposed that there is a
double current, positive in the direction zinc to copper,
and negative in the other direction, and the reason for this
supposition is because the components of the fluid in the
cell (which is called the electrolyte) are deposited, some on
one plate of the cell and some on the other: but as these
theories introduce unnecessary complications where practi-
cal work is concerned, and the explanations of most of the
electrical phenomena of the voltaic cell are satisfactorily
given on the zinc-to-copper positive current theory, we need
not discuss these matters further at present.
The electrolyte is the acidified water, or other fluid, in
the cell. The zinc is positive in the cell, according to the
theory we are using, and is called the " anode," or entering
road : and the copper is negative and is called the " kathode,"
or leaving road of the current.
If the ends of the wires from the copper and zinc be put
in a liquid in a tube, or other vessel, the end of the wire
from the copper kathode of the cell becomes the anode in
the new arrangement, and the end of 4 the wire from the zinc
anode becomes the new kathode. The point of entry of
the positive current is the anode, and of its exit the kathode >
in every case.
Whichever way the current may go it passes through
the cell, so let us examine a working cell carefully. We
VOLTAIC ELECTRICITY 7
replace the plates joined by their wires: the action starts
again and hydrogen bubbles gather on the copper: but in
whatever way we may look through the water of the cell,
in sunlight, or by artificial light, with magnifiers or without,
our eyes can detect no movement except the up and down
currents caused by the rise of the hydrogen bubbles and the
fall of the dissolved sulphate of zinc.
Let us now try as an experiment the decomposition of
water. For this we require the electricity of more than
one cell, because the resistance of water to decomposition
by electricity is greater than the force furnished by one cell
can overcome. Until there is enough force to decompose
the water it acts as a non-conductor and will not allow the
current to pass. Measured by electrical notation the
resistance of the water is T47 volts, while the force supplied
by a DanielFs cell is 1-1 volts. One cell therefore is not
strong enough, two are enough, but five will show the action
more strongly: we connect them together by joining the
wire from the copper of one cell to the wire from the zinc
of the next, by which arrangement the force is increased
just as many times as there are cells joined together in this
way. Taking then some pure water and placing in it two
platinum plates an inch apart, one of which we connect
with the free copper wire of our battery, and the other with
the free zinc wire, we see an action start at once, and from
the plate joined to the wire of the copper electrode bubbles
of oxygen are given off, and from that joined to the zinc
electrode wire come bubbles of hydrogen. And if we collect
these gases we find that there are about two parts by
measure of hydrogen to one of oxygen, which we know is the
proportion in which they are combined to form water;
and they can be tested by burning the hydrogen, and by
putting a smouldering match into the oxygen, when the
match will burst into flame.
There is no commotion in the water nor any sign of any
VOLTAIC ELECTRICITY
bubbles anywhere except at the surfaces of the plates, and
yet one constituent of the water is appearing free at one 1
plate and the other at the other plate. There can be only
one reasonable interpretation of what is happening, and
that is, that the molecules of hydrogen and oxygen are
separating at the surfaces of the plates and that in the
water between they are merely changing partners: the
hydrogen going one way, the oxygen the other, each trans-
ferred but never wholly free till they arrive at the ends
of the lines. This in the main was the theory propounded
by Grotthuss a hundred years ago, and which has since
been mishandled in various ways. The only mistake
Grotthuss made was in supposing that the molecules required
arrangement before they could interchange components.
The molecule of water is compounded of two molecules
of hydrogen and one of oxygen, and the weight of the
oxygen molecule is eight times that of the two hydrogen
molecules : the three are not mixed together to form a water
molecule but are joined as bubbles are joined, and the heavy
oxygen component always hangs below the lighter hydrogen.
So these liquid molecules require no arranging to bring
them into the proper position for work, as they are always
in position. " Chemical combination is not so much a
fusion or intermingling of the combining atomic structures,
as rather an arrangement of them alongside one another
under steady cohesive affinity/'
The length of the diameter of the water molecule is
perhaps a hundred millionth of an inch : so in every cubic
inch of the water that we are experimenting with, there are
a billion billions arranged in lines of a hundred millions,
with the first and last molecule of each line touching the
platinum plates: and all the molecules in each line are
simultaneously interchanging components with a steady
flow of oxygen towards the anode, and of hydrogen to the
kathode.
VOLTAIC ELECTRICITY 9
It has been found that a few drops of sulphuric acid assist
the decomposition of the water : but as none of the acid has
been found decomposed by the current, it probably acts as
what is called a catalyst, which is a substance, that by inter-
fering in some way, helps other substances to part or combine
without itself undergoing any change, or to put it more
correctly, that it can, at the end of the action, be recovered
quite unchanged, and that no metamorphosis is known to
have happened to it. As these are points that have no
material bearing on electricity, we may, for the purpose of
explanation, accept the reasonable theory which supposes
that in this case the acid and water molecules temporarily
combine : H 2 + S0 3 become H^SO^ : and in this form the
electromotive force can more easily disengage the hydrogen
and oxygen of the compound molecules.
The platinum plates wiien taken out and examined are
found to be quite unchanged. In the cell we found that
a chemical change must occur on one of the plates to pro-
duce a current, and here we find that the current, when once
it is established, can reproduce chemical change w r hen it
passes through water. Further, it has been found that
when the amounts of the changes in each action are
measured they are found to be equal in amount. This
is one of Faraday's discoveries.
If we could see what is taking place in the pure water
when a current is passing through it, we should see an action
going on in which there are no distracting complications,
and Mr. Whetham has almost enabled us to do this: he
placed a coloured and a colourless solution so that they met
in a narrow part of a tube arrangement, and on sending
a current of electricity through the liquids, the colour crept
along the tube, though at the very slow rate of about an
inch in three hours. This is extremely slow, but we must
remember that these things that are moving are molecules:
particles so small that a mass of a thousand of them together
10 VOLTAIC ELECTRICITY
could not be detected by the strongest microscope. The
impulses of the current move every one of the millions of
molecules in the line between the electrodes, but each im-
pulse only moves each molecule one molecule's breadth, so
though the succession of impulses may be quick, the rate
of travel they produce must be slow.
From what we have learnt in this chapter we may deduce
two facts. First, that it is plain that whatever may be
happening in a working cell, the happening is due entirely
and absolutely to action in the cell and has nothing to do
with external influences: that in fact the apparatus is
making electricity in itself. And secondly, that whether
the corrosion of the zinc before joining the wires produces
electricity or does not, we are not cognizant of any electric
current in the apparatus until the wires are joined: that
in fact the current depends on a particular arrangement
of the apparatus.
Do not let us forget these facts.
VOLTAIC ELECTRICITY
CHAPTER III
CHEMICAL ACTION IN THE CELL
WE found when we began this enquiry that electrodes of
similar metals did not produce a current, but we must add
as a rider to this rule, that they must be under exactly
similar conditions. For if we can increase the corrosion
of one of two similar electrodes, or prevent or lessen the
action on the other similar one, we can produce a current,
because we have produced a difference of potential. A
couple of examples will be sufficient to show this.
Get a U-shaped tube and nearly fill it with dilute nitric
acid. Put the ends of a silver wire, one end into each end
of the tube, and dip them one inch each into the fluid:
there is no current, though the silver is being acted on,
because the action is equal at both ends of the wire. Push
one end of the wire three inches into the liquid, and im-
mediately a current is established, and the less submerged
wire is no longer acted on.
Take out the wire and pour a little more nitric acid into
one end of the tube, and put in the wire ends to an equal
depth at each end : a current is set up because of the greater
action by the stronger liquid on one end of the wire.
So long as there is a difference of potential, that is a
difference of chemical action, no matter how it is produced
by the electrolyte, there is a current between the electrodes.
To detect the current, place the conducting wire on the
glass of a pocket compass so that the wire is in line with
the needle, and when a current passes the needle will be
deflected. The compass acts better if the glass is removed.
11
12 VOLTAIC ELECTRICITY
The Emperor Napoleon III. invented a one metal cell:
both electrodes were of copper, one in a solution of cyanide
of potassium, the other in dilute sulphuric acid, and separ-
ated by a porous partition. There have been several other
cells of this sort made, but as they are neither powerful nor
economical, they can only be looked on as curiosities and
are not of practical value.
We find in all elementary books on electricity lists of
electropositive and electronegative elements, but except
in the matter of cell construction, there is no need to con-
sider their differences of potential further than to under-
stand that their position on the list depends on the greater
or less susceptibility to chemical change in association with
oxygen which each one bears to the next on the list. An-
other list might be made of the elements in their chemical
relation to chlorine, and so on: and every one of the sub-
stances can be made, as shown above in the case of silver,
at once electropositive and electronegative to itself.
Both the zinc and the copper are acted on by the acid
in the cell when the wires are not joined; but when the
circuit is completed, the corrosion of the copper is suppressed,
because the acid and oxygen move towards the zinc and
only the hydrogen can reach the copper, on which it has
no action.
In this common cell that we have been using, the hydrogen
forms in little bubbles on the copper and coats it. The
action of the cell is very much and very quickly weakened
through this, and it is then said to be polarized. The gas,
being an undecomposable element, is a nonconductor of
electricity, and it prevents some of the current from reach-
ing the copper: also the gas, immediately after its decom-
position from water, is more oxidizable than the zinc, and
sets up a current in opposition to the zinc current. Thus.
the hydrogen acts injuriously in two ways; and the electro-
motive force may be so lowered that the polarization current
VOLTAIC ELECTRICITY 13
may become as strong as the direct current and stop it.
Various remedies have been devised to overcome this : such
as sweeping the copper surface, or blowing the gas away
with air: taking up the hydrogen by some combining sub-
stance in the electrolyte, such as chlorine or chromate of
potash : or, which is much the best, preventing the gas from
getting to the copper by putting a porous partition between
the electrodes.
Something, however, must be deposited on the copper:
some chemical action must run through the electrolyte
the whole way from the anode to the kathode, or the cell
does not work. The copper need not be acted on in any
way chemically : the hydrogen bubbles have no such action
on the copper and no affinity with it, and merely adhere
to it consequent on the impulse of the current in that
direction, and their own feeble attraction of cohesion:
but action in the electrolyte must extend the whole way
across between the electrodes. A plate of heated zinc and
a plate of platinum joined by a wire and put in a jar of oxy-
gen, give no current, although the zinc combines with the gas,
because there is no action in the medium between the metals :
the intervening gas is an element and is not decomposable,
and therefore carries no current. If the plates were placed
in a mixture of gases, the action of the gases on the zinc
would probably set up a current combining them (perhaps
with explosion) in the space between the plates, and the
arrangement would then act like an ordinary cell. But
without compoundable substances between the plates no
electricity can be produced in a cell.
The fact that there is no current between the electrodal
plates in oxygen in the experiment mentioned above, has
been spoken of as a proof that chemical decomposition as
well as chemical composition must occur in the working
cell : but this does not follow, for electricity can be carried
by chemical combination acting alone. An electric spark
14 VOLTAIC ELECTRICITY
will pass through a mixture of hydrogen and oxgyen, and
is able to do so because of their combination into water.
In air, the lightning flash passes because it compounds the
mixed oxygen and nitrogen of the air. And the flash
discharge can be forced through oxygen, which is an ele-
ment and is not decomposable, but is compounded, with the
help of the electromotive force, into its triad ozone. There-
fore we may conclude that chemical composition is necessary
to carry the current, and also that composition alone is
necessary.
It follows as a corollary to the theory of Grotthuss, that
no substance can pass from one electrode to the other unless
it is combined with some other substance which passes in
the opposite direction : and if we mix any powdered element
in the electrolyte, whether the powder be metallic or other-
wise, such as " pulverized charcoal, sublimed sulphur,
spongy platinum, or precipitated gold, though they are
in such small particles that they remain suspended in the
fluid for hours and are perfectly free to move if impelled
to either pole, they show no tendency unless they are
brought into relation by chemical affinity with some other
substance present in the fluid/' This is true except that an
elementary molecule can, in some few instances, combine
with others of its own sort, as in the case of oxygen, which
combines in threes to form ozone.
Molecules that are already combined travel by separation
and recombination to the electrodes, t but either or both of
their components may be stopped by secondary combina-
tion, provided always, that they transfer their action to
another set of molecules so that it may be carried forward
by them. The working of a cell with a porous partition
depends on this, and a description of a DanielFs cell will
explain this better than any mere theoretic talk.
The outer cell of the Daniell, which acts as kathode,
is a little copper pail, and is filled with saturated solution
VOLTAIC ELECTRICITY 15
of sulphate of copper, which is kept at full strength by
crystals of the salt placed in a perforated trough round the
cell inside near the top. The inner cell is of porous earthen-
ware, and has in it a dilute acidified solution of sulphate
of zinc, and an anode of amalgamated zinc, and the only
precaution needed for this part is to see that the solution
does not become saturated. The acid of the sulphate of
zinc solution with the oxygen of the water together attack
the zinc, and produce sulphate of zinc which is dissolved as
fast as it is made, and the hydrogen from the water is
deposited on the porous cell. The current produced on the
zinc by the chemical action passes to the porous partition,
where it meets the sulphate of copper solution, and prefer-
ring to work on the copper salt to working on the water
it is dissolved in, it separates the copper from its oxygen
and acid and deposits the metal on the kathode : the oxygen
from the copper passes through the porous partition with
the free acid and removes the hydrogen as fast as it collects
there. The copper deposited on the copper cell can of
course do it no harm, and the Daniell is therefore very
constant, being free from any resistance except that of the
working of the electrolytes in themselves.
The reason why the current should prefer the copper
salt, as a carrier, to the water it is dissolved in, has not
apparently, so far, been explained: but it has been found
that, in a mixture of substances, those elements that are
least prone to oxidation are those that the current chooses
to separate and deposit first. Free copper is found in.
many parts of the world, so we may consider that it is not
easily oxidized, and as it is easily extracted from its ores,
that it is also easily dissociated from oxygen: free iron has
been found in a thin vein in America, and associated with
other minerals in meteorites, but it may be said to be very
rare ; it is very prone to oxidation, and is difficult of separa-
tion from oxygen: and hydrogen, though it is everywhere
16 VOLTAIC ELECTRICITY
present with us in its oxidized form as water, is conspicuous
by its absence in a free state from our entire system, ex-
cepting the atmosphere of the sun. We judge from this
that the elements vary in their hold on oxygen: that the
cohesion between the molecules in some compounds is
weaker than in others: that fewer impulses of the current
are needed to free the copper than the hydrogen from
oxygen: and we might add, that the current evidently
takes the easier way, and that if the easier way substance
is not sufficient for its wants, that it will fill up the gaps in
the chains of molecules by using those of the next easier
substance.
The presence of hydrogen in the atmosphere of the sun
is a proof, if any is wanted, that no chemical action occurs
in the sun, and as a consequence that there is no electricity
in the sun. The sun cannot send out electricity because,
as we are apparently beginning to find out, combination of
material is necessary to its production. Therefore as this
hydrogen, which with us is a most obstinately associating
material, is found in the sun free, it is most unlikely that
any other substances should be chemically combined there,
and that therefore, so far as we know, that no electricity
can be produced there.
A certain author writes as follows: " The light of the
electric furnace is due to the combustion of carbon. There
is carbon in the sun. Therefore the sun is an electric
furnace/' But it does not do to jump to conclusions quite
so rapidly. We might with equal plausibility say the
light of a tallow candle is due to the combustion of carbon,
therefore the sun is a tallow candle. There is no carbon,
but only carbon vapour in the sun. Carbon sublimes with
out melting at about 3500 C., and is therefore a gas at a
temperature much below that of the sun. All the sun's con-
stituents are excited far beyond chemical combination; so
there is neither burning of carbon nor electricity in the sun.
VOLTAIC ELECTRICITY 17
Sir Humphry Davy proposed to use the action of pref-
erence for the protection of the copper sheathing of ships :
using small pieces of iron, distributed at intervals, to take
up the corrosion due to the chlorine in sea water, and so
save the copper. So far as the preservation of the copper
went, it was a success : the iron was corroded and the copper
saved: but it was a failure commercially. The barnacles
and seaweeds collected on the clean copper of the pro-
tected ships and lessened their speed of sailing, while the
oxychloride on the unprotected copper of the other ships
kept them comparatively clean: and the loss of time was
more expensive than the loss of copper.
It is perhaps unnecessary to give any further explanation
of the action in a cell with a porous partition, but it is well
that it should be very clearly understood, and the descrip-
tion should be studied carefully.
The only use of the original sulphate of zinc in the
solution is to prevent the copper solution from passing
through the porous cell by osmosis.
As the electrolytic action must pass over the whole dis-
tance between the electrodes, and do the same amount of
chemical action in each solution that it passes through,
the energy of a cell is not increased by preventing polariza-
tion, it is merely prevented from decreasing. By keeping
the kathode clean, the whole of the electrolyte between that
surface and the anode is filled with lines of current: but if
any part of the anode or kathode is covered, the action
opposite that part is stopped. The only advantage there-
fore of oxidizing the hydrogen in Daniell's cell is that the
cell suffers no loss of activity.
What is called osmosis, is the passage of fluids, with or
without salts in solution, through the pores of substances
such as unglazed earthenware, skin, parchment-paper,
and such like. In the herring-curing places, when there
was a tax on salt, they used osmosis to save salt, and perhaps
2
18 VOLTAIC ELECTRICITY
they do so still. Liquids with salts in solution will pass
through the porous material, but not any of the substances
that preponderate in animals and which from their likeness
to glue are called colloids, not even when they are in
solution. The dirty salt used for curing the herrings and
the offal mixed with it were put, with a little water, in a
parchment bag, and the bag into a tub of water, and in
a short time the water in the tub acquired most of the salt,
and then this water only needed boiling to recover the salt
clean.
The following is a pretty experiment that anyone, even
a non-smoker, can do if he has a little gold to spare. Break
the stem off a new clay pipe, and plug the hole in the bowl :
then fill the bowl with nitric acid and put it in a wine-glass
in which are some hydrochloric acid and a piece of gold
leaf. The leaf will be immediately consumed if touched
with the end of a loop of gold wire, the other end of which
is in the nitric acid. Now gold is not soluble in either of
these acids alone but is so in the two mixed, and the result
is not nitrohydrochloride of gold but simply chloride of
gold. Nitric acid, hydrochloric acid, and gold, HN0 3 +
3HC1 + Au, become nitric acid, hydrogen, and chloride of
gold, HNO 3 + 3H + AuCl 3 . Th'e nitric acid acts as a catalyst
and is found unchanged at the last. Probably by its
superior attraction for hydrogen it loosens the cohesion
of the hydrogen and chlorine in the hydrochloric acid and
leaves the chlorine more free to attack the gold. In this
experiment the porousness of the bowl is necessary, for
without it there is no action. The action is started by some
of the nitric acid creeping by osmosis through the bowl,
or perhaps by some that oozed through when we filled it,
and a few of its molecules have set up a very slight chemical
combination with the gold leaf before the wire comes into
play. Once the current is started, the chlorine pours upon
the gold leaf and soon consumes it, because the excess of
VOLTAIC ELECTRICITY 19
potential is all on the hydrochloric acid side as the nitric
acid has no action on the other end of the gold wire.
" Solutions of electrolytes exhibit chemical activity in
the highest degree, because they are of the substances
whose molecules are most easily discombined by either
force (electrical or chemical). Also electrical force can
assist chemical force to results that by itself it cannot
attain/' Nevertheless the two forces are in opposition
to one another in electrolysis. If we examine the electro-
lyte for change produced in it by the current, we find none
except perhaps the addition of some salt by the chemical
corrosion of the anode. In the case of pure water we find
that there is merely less water : and in saline solutions that
there is a weakening of the solution : but otherwise there is
absolutely no change of composition. The element that
can combine with the anode goes towards it, and that which
cannot goes the other way: there is interchange between
the molecules in the liquid, but no sign that chemical action
has set any of them free: and yet there may have been
violent electrolytic action. Electricity discombines the
components of the molecules of the electrolyte, and chemi-
cal activity combines them again. The action and reaction
in the body of the electrolyte are equal and they are opposing
actions.
Chemical action is always an action of combination.
Even when it seems to separate the elements of compound
molecules it does so merely because of the superior cohesive
attraction of the elements in some new arrangement. It
is always an attractive force, never a repulsive force, and
can only make combinations. And the electric force is
always a repulsive force and can only make dissociations.
There is in the cell, chemical combination on the zinc,
and chemical combination and electrical dissociation in the
electrolyte.
VOLTAIC ELECTRICITY
CHAPTER IV
THEORIES OF ELECTROLYSIS, AND ACTION AT THE ANODE
WE have only as yet mentioned one theory of electrolysis,
and what we have accepted in it is really only that part of
the theory of Grotthuss which explains the mode of passage
of the electricity between the electrodes; but besides the
theory of Grotthuss there are several others, and it is only
fair that we should consider them with a view to deciding
whether any of them gives an explanation that agrees better
with the facts of electrolysis than that we have so far used.
It is a pity that our instruments are not fine enough to reveal
the action going on in the space between the electrodes, and
until they do so, we must accept some interpretation of the
facts due to that action, and naturally we will choose that
theory which best explains them to us.
Faraday, perceiving that the molecules of the electrolyte
were employed in some way on this transfer work, supposed
that they carried packs of electricity, and gave them the
name of ions (travellers), which was a reasonable enough
name, though they would have been thought to be ver}^ slow
travellers, even in those days of stage coaches, if their rate
had then been known. Since then we have learnt that
electricity travels with extreme rapidity, and that the
actual movement of the molecules is somewhat slower
than the pace of a snail, so any such pack-carriage idea
is impossible as the transfer is made instantaneously over
great distances.
Grotthuss supposed that the constituents of the com-
pound molecules were severally electropositive and
20
VOLTAIC ELECTRICITY 21
electronegative. That in water, for instance, the hydrogen
is positive and the oxygen negative, and that they are at-
tracted by the electrodes: and that when a current of
electricity passes, that they change partners all along the
line, and the liberated hydrogen and oxygen molecules at
each end give up their charges to the electrodes. Here
again we have impossible pack-carriage. If a momentary
current is sent through the cell, it is instantly and entirely
carried across and there is no electricity remaining in the
electrolyte as would be the case if the action were as above.
Clausius tried to improve upon Grotthuss' theory by
adding the separation of elements in solution. His theory
is, that when a salt is dissolved it breaks up into its con-
stituents, which wander free till by chance they find other
temporary partners : the electromotive force of the current
is supposed to control the direction of these chance wan-
derings, urging one set of wanderers one way, and the other
set the other way, and so shepherding them to t the two
electrodes if lucky enough to have prevented an escapade
on the way. This theory supposes, for instance, that a
solution of common salt sodium chloride and water
contains wandering elementary molecules of sodium and
chlorine. But this condition is not possible, as there is no
sign of colour from free chlorine, nor of combination of
s odium with the oxygen of the water which is a very violent
action. And besides if these molecules of the salt had the
power given them to burst the bonds of cohesion which are
weakened in proportion to the square of the distance of the
particles asunder, what earthly force could bring them to-
gether again ? And in what conceivable way does this help
the current ?
Since Clausius published his theory, enthusiasts have
added to it and now the conductivity of the electrolyte is
supposed to be in " proportion to the number of free ions
multiplied by their velocity/' That in an extremely dilute
22 VOLTAIC ELECTRICITY
solution all the ions are free, and by strengthening the
solution, although it increases the number of ions, it does
not increase the number that are free, and the conductivity
of the solution is not therefore proportionate to the strength.
Also the velocity of the ions is supposed to depend on the
frictional resistance, or viscosity of the electrolyte: and
their number depends upon the solvent, water having more
than benzene or alcohol.
If one starts to explain a myth, it is easy enough to find
reasonable explanations for all its fancies, and to string
them in support of one another. Ovid could give us some
instances of this sort. There is no possible use for free ions,
and any snail-like velocity they could have would be of
no help to electricity. The conductivity of an electrolyte
probably increases with its strength, but not the action
at the anode, because the interaction between the oxygen
and zinc must be limited by the amount of zinc surface.
Any thing 'added to thicken the electrolyte, such as gum,
sand, sawdust, should, one would suppose, certainly ob-
struct the action: and alcoholic and other solvents would
resist the electromotive force more than water, because
these fluids are more resistant to chemical change, and not
because they have solutes in them. Pure water can be used
as an electrolyte, but do its ions wander about free ?
One modern theory is that a compound molecule is com-
posed of two parts: one of these, the metal kathion, has a
positive charge of electricity bound in it, and tries to get to
the copper : and the other, the acid radical or anion, has a
negative charge and makes for the zinc. All of them to-
gether, whether anions or kathions, carry equal charges,
and when they give them up at the electrodes they receive
an opposite charge. This is a plentifully complicated rein-
carnation of Faraday's idea. Here we have molecules
whose preference for a particular charge is so great that
they hold it regardless of the opposite charges held by their
VOLTAIC ELECTRICITY 23
partners, giving up these charges they love, to take on
-charges they do not want, and receiving these obnoxious
charges from a body that must have a store of both sorts
mixed together. It is too complicated altogether and is
merely another specimen of pack-carriage.
The pack-carriage theory dies hard. It is so simple, so
evident, so undemanding of thought. Each ion takes up
its load and darts across with the speed of light and the
thing is done. Each molecule holds some of both elec-
tricities and pours them out, either, or neither, or both
together as occasion demands.
The discovery of the slow movement of ions has upset
the package idea, though obstinate enthusiasts still insist
upon carriage by ions and corpuscular charges and measure
the velocity of matter in exhausted tubes by the effect of
the rays it produces. Hydrogen is said to be the fastest
of the ions. With " one volt per centimetre force " to
drive it, it takes an hour to travel four inches, under the
best of circumstances: and this is " ten times as fast " as
most ions move. The electric current travels with a velocity
comparable to the speed of light, and if any component of
an electrolyte were to travel with but a small part of that
speed, the fluid would disappear in a moment in a flash
of ardent heat.
Sir Oliver Lodge says that " the energy of one milli-
gramme rushing along with the speed of light, is not less
than fifteen million foot tons/' Which is conclusive
proof that none of the material driven by electricity, or in
any other way, goes any way near the speed of light, for
no vessel could hold it.
The latest theory is the electron theory, or rather two
theories. One of these supposes these electrons to be
" small aggregates of electricity " that thread their way
between the ions: and the other, that the electron forms
part of the ion and is shot out of it. They are both
24 VOLTAIC ELECTRICITY
variations of the pack system with the definitely added
declaration that the electricities are material.
The swiftest motion of material is a snail's pace compared
with that of electricity, so electricity can be nothing but
motion: and there can be no aggregation of anything that
is not material. Every modern theorist is convinced that
electricity is motion, and yet they cannot get themselves
to abandon the favourite old idea that it is part of matter
like the raisins in a pudding. Electricity is a motion that
can act on matter, and matter has no motion till motion
is given to it. There is no electricity, no heat, no light, no
sound, no motion of any sort in a molecule until a motion
is transferred to it ; as Soddy says, " there are no permanent
resident forces in matter/' and its sole inherent quality is
inertia or opposition.
If the electricities were substances residing in the mole-
cules, their loss would cause loss of weight, and also the
completion of the circuit by joining the wires would not be
necessary. The oxygen will corrode the zinc whether the
wires are joined or not, and if any material electricity could
be poured upon, or shot at the zinc, by the oxygen, it should
be found there whether there were an outside arrangement
of wires or an absence of such mechanism. But the junction
of the wires is necessary, and it is so because the electricity
is not a substance but a motion that requires a circuit to
travel on.
Electricity, whatever particular motion it may be, is
evidently a motion produced by the chemical action on the
zinc : it is due to the combination of oxygen with the zinc,
or other material of the anode: and there is none of the
motion of electricity anywhere in the electrolyte, or in the
wires of the circuit, till this chemical combination sends it
forth. The oxygen is drawn, by the cohesive powers of
zinc and oxygen, away from the cohesion of oxygen and
hydrogen, to join the zinc and leave the hydrogen: and this
VOLTAIC ELECTRICITY 25
act of junction produces a motion: and this motion passes
through the electrolyte reproducing in every molecule the
action that produced it, causing every molecule of oxygen
to separate from its hydrogen and to combine with the
hydrogen of the molecule nearer the zinc : and the last of
the hydrogen molecules at the copper is set free. A voltaic
cell can be made of zinc, copper, and pure water, and the
above is a description of the uncomplicated action in such
a cell.
It has been said that " electric decomposition is the pre-
ponderance of one set of chemical affinities over another
set less powerful: so chemical affinity and electricity are
the same/' But this is quite wrong. What difference
of chemical affinity is there between two molecules of water ?
Electricity is an impulse that tends to separation, and
chemical affinity is a cohesive force: by acting together
they produce electrolysis, but they are different forces.
It is much more correct to say that " in every case of
chemical change there is a coincident electrical change, an
electric flux every case of electrical change is accompanied
by chemical change : the force of chemical affinity is in some
way disturbed by a momentary displacement of the mole-
cules when a current passes through a conductor/'
" Difference of potential produces electromotive force,
which produces a current as soon as a circuit is completed/'
The chemical cohesion on the zinc sends out an impulse that
decomposes the electrolyte, and this decomposition, in its
turn, necessitates fresh chemical composition. The two
impulses electrical and chemical are not quite equal,
the electrical being the stronger, and they represent the
swell and hollow of the wave of current, and the action goes
on in every molecule used by the current. The material
and the movement are, the one a thing moved, and the
other forces that move the thing, and we must see that we
do not get them mixed. The entire electric current is
26 VOLTAIC ELECTRICITY
made up of the thing moved, and the two forces, electrical
and chemical, that move it.
To produce any particular sort of energy a greater
amount of energy must generally be expended: and in every
case the prime mover is gravitation under one or other of
its several names, and the origin of this force we do not
know/ but it is a force that seems to be constantly renewed.
" Electrical attraction ceases on contact, but this cessation
of attraction does not seem to occur among atoms/'
The Falls of Niagara have plainly a great force of gravi-
tation, and some part of the falling water is used to work
machinery to produce electricity, and yet but a small part
of -the force so used is found available when the current is
turned to domestic use. In other places steam-engines
are used to work the electric generators, and here again
there is a great loss of power, for only an eleventh of the
cohesive power developed by the carbon and oxygen in
uniting to form carbonic gases is found available at the
last, the rest, more than ninety per cent., is lost for working
purposes. Of course this lost energy is not dissipated at
this enormous rate, but is used to heat the engine, elevate
the smoke, and so forth, but so far as the resulting electricity
is concerned it is a dead loss. The waste of energy in the
voltaic cell does not seem to have been measured, but it
is certainly very much less in proportion to electric out-
turn than with any other method, and this mode of producing
current would be the best we know of, if zinc were as cheap as
coal: its price being what it is, it is a most expensive method
and so is unsuited for commercial use.
" No pile or battery can generate a sensible current, except
by a sensible consumption of its materials in the shape of
chemical action/' and "every disturbance of electric
1 Since discovered by the author.
VOLTAIC ELECTRICITY 27
equilibrium is inseparably connected with an equivalent
disturbance of the molecules of matter/' and " the intensity
of the current is in proportion to the intensity of the chemi-
cal affinity of the zinc for the oxygen/'
The zinc must be consumed or we get no current. Noad
says that the electrodes have no attracting power, though
acid inclines to the one, and bases to the other. The
hydrogen that accumulates on the kathode does not cohere
to it but leaves it quite free and unchanged/' Other
authorities, on the contrary, say that the action is entirely
due to attraction. Perhaps Noad meant to say, that there
is no increase of attraction of cohesion and attraction of
chemical affinity due to electricity, for all bodies have the
first and many the second attraction: and without the
action of both these forces at the anode there is no current.
But most persons would say that the chemical attraction
is increased by the current in the cell : certainly the action
is immediately increased by closing the circuit . The current
must circulate many million times in a second, and with
each circuit pushes some oxygen molecules against the zinc,
which without this stimulus would not have moved. So
though strictly speaking the force of chemical attraction
has not increased, the amount of chemical action has.
" It is the union of the zinc with the oxygen of the water,
that determines the current in a common voltaic battery:
and the quantity of electricity is dependent on the quantity
of zinc oxidized/' This is certainly true, and we have now
to go into the details of the operation.
'A solid molecule of zinc combines with a liquid molecule
of oxygen to make a solid molecule of oxide of zinc. Before
they join the zinc molecule is a small crystalline solid of
some compact form, and the oxygen molecule is a liquid
sphere. They come together and form a solid crystalline
molecule, and they do this with contraction and, perhaps,
the discharge of heat : the oxygen molecule becomes smaller
28 VOLTAIC ELECTRICITY
as solid than it was as liquid, and the zinc and oxygen con-
tract in joining owing to the cohesive force of their mutual
embrace: so there should be heat because of the double
contraction. Yet as this solid oxide of zinc molecule is
immediately changed by solution to liquid and therefore
expanded after joining the acid molecule, there is no heat
to be found in the cell because the expansion absorbs as
much heat as was discharged by the contraction.
Now, in coming together, the zinc and oxygen molecules
approach each other with constantly increasing velocity
till they actually strike, not as solid and liquid, but as two
solids, producing as they do so a concussion, which sets up
a motion a vibration and this vibration is the electro-
motive force, and it is a vibration of aether, for no other
material could convey it so fast, and the aether set in motion
is that of the materials of the cell.
Let us carefully consider the conclusion that we have
now arrived at. It is not one due to any theory invented
for the occasion: nor to any mathematical equation bol-
stered with changeable constants to produce a suitable
answer: but depends entirely on well-known facts, and
these facts are in detail as follows.
In a solid compound of which one component is a gas>
the gas is solid.
In chemical combination the different molecules attract
one another.
In attraction the force increases with decrease of distance
in proportion to the inverse square of the distance.
In chemical combination some form of aether disturbance
is always evident: either actinic, light, heat, or electric:
and the disturbance is produced by the impact of the mole-
cules that are combining.
In the case we are considering, the aether disturbance is
produced in the apparatus we are using, and therefore in
the aether in the apparatus.
VOLTAIC ELECTRICITY 29
No material, solid, liquid, or gaseous, can move with a
velocity at all comparable with an aether vibration.
Based on these facts, which are plain enough, it appears
that the electric current in the cell is a form of aether wave
emanating from the combination of the zinc and oxygen,
for it is unlikely that the union of the liquid acid and oxide
molecules should produce concussion, and as the current can
be produced in plain water without any acid, we may con-
clude that only the alliance of the zinc and oxygen is acting
to produce the vibration. And here we find confirmation
that force must be expended to produce force. The mutual
energy of gravitation, or, as it is called in this case, chemical
affinity, between the zinc and oxygen, produces an impulse
which we call the electromotive force, which force, as it
passes through any liquid, produces in it a change equivalent
to the change that produced itself : it produces one equiv-
alent of chemical change no more, no less whatever
the fluid may be composed of. In an inch of water between
the zinc and copper, the molecules are arranged in lines
of a hundred millions in a line : the combination of one mole-
cule of oxygen from the water with one molecule of the zinc
produces a vibration of associated aether that separates
the oxygen and hydrogen in every molecule of the water
in a line of a hundred millions, and the vibration having
travelled to the end of the line there liberates one molecule
of hydrogen from the water no more, no less.
In this, as in all cases of transmission of energy, a part of
the electric force must be used up in its passage; but we
must not suppose that when a current finds the distance to
be travelled too long for its powers, that it gives up in con-
sequence of the aether wave being reduced in amplitude
and at last failing to do more work after going a certain
distance. The force puts a strain on the conducting
material throughout the whole distance at once, and if it is
strong enough to complete the separation of all the mole-
30 VOLTAIC ELECTRICITY
cules in that line, the current passes, and not otherwise.
This is shown to be the case by the effect of a storm cloud
on the earth : the negative on the earth is drawn under the
cloud and there is a strain established in the air between
it and the cloud before there is any possibility of the passage
of the current : when the distance is so reduced that the force
can overcome the resistance to electrolysis of the air through
the whole distance, the flash falls, and not before.
We have in this chapter discovered that the source of
electricity in the voltaic cell is chemical combination:
what we have now to find out is, what produces electricity
in other forms of apparatus and in nature. If you will look
back you will agree that none but simple well-known facts
have been used in our examination. There has been no
invocation of any of these extraordinary and mysterious
agencies so dear to modern science: " which show more
ingenuity than intellect in creation": " whose multitude
shows their futility " : and which containing imaginary
mechanisms inconsistent with the laws of motion are only
comparable to ancient vain attempts to manufacture per-
petual motion machines and on account of this ver}<
simplicity on our part, you must be prepared to see your
conclusions ignored, or condemned and smothered in
nebulous inanity: but hold fast; truth will conquer in the
end, and perhaps before we finish our work we may have
converts to our new credo.
VOLTAIC ELECTRICITY
CHAPTER V
THE CURRENT AND ITS EFFECTS
THE motion of electricity acts like any other motion. You
strike a ball : it rolls along and hits another ball : the first
stops and the other rolls away. The vibrations of radiant
heat act upon a body : which in turn sends out reproduced
vibrations to act on another body. The zinc draws the
oxygen molecule towards it : they join and send out a move-
ment to act upon another oxygen molecule and cause it
to separate from its hydrogen and move in the same direc-
tion. And this movement is the product of two distinct
forces, electrical impulse, and the chemical cohesion that
caused it : and this causes the separation and recombination
of the molecules of the electrolyte. In fact this vibration
produces the same series of actions as those by which itself
was produced. In all wave actions this is the case. The
expanded molecules of the sun contract and produce radiant
vibrations : these expand the molecules of earth's substances,
which in their turn contract and reproduce vibrations to act
on other molecules, and so on continually. The separate
zinc and oxygen molecules come together and produce
vibrations: these separate other molecules which come to-
gether and reproduce vibrations.
So far as we can discover, then, electricity in the cell is an
aether wave originating in the conjunction of solid molecules.
And apparently there are two movements in the wave.
First a movement caused by the chemical attraction, and
second the movement that this originates to send the basic
molecule to the kathode. And this duplex electric wave
31
32 VOLTAIC ELECTRICITY
formed by chemical combination and electromotive separa-
tion is the current, and it passes with great speed through
electrolytes and on conductors. However we agreed when
we began that we would put off our final decision till we had
gone through every phase of the subject, so we will leave it
for the present, and go on with our examination of voltaic
action, only bearing in mind particularly to notice whether
we come across, in any future study, any action that does
not fit in with this deduction.
*****
Let us now consider the arrangement of cells in a battery.
As may naturally be inferred, two cells, or more, produce
more effect than one : but it has been found that the sort of
effect that they produce depends on the way in which we
arrange them.
If we join the positive (copper) wire of one cell to the
negative (zinc) wire of the next, and so on in rotation, the
cells are said 'to be in series, and the electromotive force
is multiplied according to the number of cells, but the
quantity of current is but little more than can be produced
by a single cell. The force from each cell passes through
and reinforces every other cell, but the amount of current
is restrained by the size of the plates in the cells. It is like
water in a pipe when the pressure is increased : the gauge of
the pipe prevents the jet from becoming any thicker, but
it comes with greater force. The electromotive force
generated in a cell by the composition of its oxygen and
zinc can only decompose an equivalent amount of water in
that or any other cell, and the quantity of electricity is not
therefore much increased by addition of cells in series, but
its intensity, that is the amplitude of its waves, is increased :
the action of cohesion is somewhat assisted but the strength
of its produced vibrations greatly increased. Poggendorf
came near this solution in 1840.
If we join all the copper wires together, and all the zinc
VOLTAIC ELECTRICITY 33
wires together, the battery is in parallel, and it gives more
current, but the electromotive force is only equal to that of
one cell. The rate of production of the force in each cell
is the same as when acting separately. It is like the dis-
charge of a number of water pipes of equal gauge and under
equal pressure into a common conduit: the quantity of
water depends on the number of pipes, but the velocity is
no greater from the increased number.
" The strength or intensity of the current depends on the
resistance and the electromotive force of the cells/' The
electromotive force in the cells is the impulse produced by
the concussion of the zinc and oxygen molecules : it may be
feeble or strong according to circumstances, but always
produces the same length and velocity of wave: the only
difference in the produced waves is in their amplitude: a
feeble electromotive force can only produce a shallow wave,
and can push its effect, that is the current, but a short way :
the stronger the force, the deeper the wave': the less the
resistance, the further any wave goes. When the molecules
of the conveying material are strongly combined together,
the electromotive force must be stronger to separate them,
or no current passes. But this resistance of conductors we
will consider in another chapter.
The current is the dissociation and recombination of the
molecules resulting from the impulse of the chemical action
at the anode : it is a wave movement acting on the molecules
of the electrolyte: the impulse passes very swiftly and the
movement of the molecules is instantaneous with it, but
their progressive movement is very slow. The action is
like that of the great tidal waves which move across the
ocean at near a thousand miles an hour and scarcely displace
the position of any of the drops of water.
*****
The voltaic current, as compared with electricity other-
wise engendered, is a broad and shallow stream which
3
34 VOLTAIC ELECTRICITY
requires an ample conductor, or it will be interrupted and
then many 'of its impulses will produce heat vibrations.
" It has a great heating effect owing to its quantity, but
it has little violence of electric shock and sparks are difficult
to obtain/' Or, as Noad says, "The intensity of voltaic
electricity as compared with statical is extremely low, but
the quantity extremely high/' The electricity produced
by a statical machine depends on the action of materials
very much excited by friction, with a resulting intense,
but slender current. The voltaic electricity depends on the
gentle chemical activity of the anode, with the result of a
mild current, and " the quantity of electricity in a voltaic
battery depends on the size of the plates, the intensity
on the number of cells/'
This naturally makes a great difference in the physio-
logical effects of this current as compared with that which
comes from statical electricity. That gives one a racking
shock, with painful contraction of the muscles. This gives
a disagreeable aching at the joints and sometimes an itching
of the skin, but no muscular distortion or agonizing spasms
of pain, except, by the way, that " if the slightest excoriation
or cut happens to be in the path of the current, the pain
is severe/' The writer from whom the above extract is
taken does not explain why : but we know that it is because
the electricity acts electrolytically on the moisture at the
place and bathes one side of the cut with fresh acid and the
other with fresh alkali, neither of which can be pleasant
to exposed nerves.
According to Berzelius, " the taste of the positive current
directed on the tongue is acid, and that of the negative
current caustic and alkaline." If you will put a piece
of zinc under your tongue, and a half-crown above it, and
let the edges of the metals join in front of the tongue, you
will feel a curious tingling sensation, and have a taste like
potash : if you put the silver below and the zinc above the
VOLTAIC ELECTRICITY 35
sensation is the same, but the taste is acid. We have here
a small voltaic battery in which the saliva acts on the zinc,
and with the blood and nerves forms the electrolyte between
the metals.
All the senses, seeing, hearing, smelling, besides tasting
and feeling as we saw above, can be excited by similar
arrangements. This action on nerve was in its day a great
discovery and led to the construction of the voltaic pile,
but such experiments are to-day merely tricks for the
curious and tell us no more than that the blood and other
fluids of the body are made up of substances that are de-
composable by electric currents.
The body is not a good conductor and the resistance it
gives to the voltaic current prevents all but a small part
from passing, and for the same reason the current passes
through or over every part of the body that is any way near
the line between the conductors. Statical electricity
might send even less current through, but it would send it
in one nearly straight line, and with great force overcoming
all resistance : hence its destructive effect.
" In the human body the blood is the best conductor,
then the nerve substance." The blood is coagulated by
strong currents, so it is not advisable for funny persons to
play tricks with electricity: a certain amount of current
means death, so let no one treat a friend to a shock till he
has tried it on himself : the friend might be a sensible person
and a loss to society. " Electricity in the first place acts
upon the nerves causing spasms, secondly it destroys the
tissue either by burning or electrolysis, the blood becoming
coagulated. To restore a person who has been rendered
insensible by electric shock, all the same restoratives should
be used as for a person drowned. Electric currents should
not be used at all except with great care and under the
direction of a regularly trained surgeon. In the few cases
where some fancied good has accrued (from advertised
36 VOLTAIC ELECTRICITY
magnetic and galvanic appliances) the curative agent is
probably not magnetism but flannel." This is from Silvanus
Thompson's lessons in electricity and magnetism, and is
very good advice.
Without going into particulars of experiments with legs
of unfortunate frogs, or horrible descriptions of the effects
of electricity on dead criminals, there are one or two points
worth considering with respect to the action of the current
on the animal system. Some scientists say that our entire
nervous system is worked by electricity : that the nerves are
a mere set of voltaic batteries and that their action is simply
due to a creation of difference of potential between the two
ends of the nerve: that if you heat one end, presto, the
current carries the news to the other end and the appropriate
muscles respond. But this theory is founded on vague
generalities and not confirmed by experiment.
There are two points to be borne in mind. One is that
there must be a complete circuit for a current to traverse :
and the other is that the voltaic current must travel along
a nerve to produce contractions in a muscle, for it has been
found that muscle by itself is a nonconductor and is not
acted on by this sort of electricity.
It seems rather against the idea that the nerves work by
their own electricity, that contraction of muscular fibre
cannot be effected by electricity directly applied to muscle,
but is easily set up when the nerves are used as conductors
and the current sent to the muscle through them. And
the following also is against the idea namely, that though
the nerves are constantly in connection with muscle, they
are not constantly acting, which they should do if they
formed a circuit and were electricity producers.
Another strange thing is, that other substances contain-
ing contractile filaments, such as protoplasm and plants
with sensitive leaves, both of which have these filaments,
are contracted by a current through their substance though
VOLTAIC ELECTRICITY 37
in them no nerves have been found. It certainly seems as
though the electrochemical changes produced by the
current in those substances irritate the filaments and so
make them contract : and if so, we should think that a similar
cause occasions the contraction of muscle : that in fact the
nerves set up chemical change in the substance outside the
filaments of the muscle and thus cause their contraction by
the action of the changed substance on the muscle. It is
quite certain that no filament is lost through exercise,
and if not, then the loss must be in the interfilamentous
substance, and on this supposition we can understand
fatigue coming on when all the change possible in
this substance has been done by the nerve action and
there is no more left to be changed to do work on the
filaments. The worn-out stuff that is left is not poison,
as some say, except that it occupies the place of fresh un-
changed material and must be carried off to make way for
it, and now is the time that stimulants to the circulation
are useful to induce nature's commissariat to hurry up a
fresh supply of what is needed, and which by its action will
give, what is called by runners, second wind.
The muscle is only contracted by electricity when the
current through the nerve is made or broken : a continuous
current has no effect. The direct current, that is the current
that is in the direction of the ordinary nerve current away
from the brain, affects the motor nerves most on making
the circuit, and the sensory nerves most on breaking it : and
vice versa with an oppositely directed current. The sensa-
tion felt by the sensitive parts of the body is greater towards
that part that is nearer to the negative side of the battery.
If the current travels along the motor nerve away from the
brain, that is with the negative wire on the muscle and the
positive on the nerve, there is strong contraction : with the
positions of the wires reversed the contraction is feeble.
It would appear from all this that when a voltaic current
38 VOLTAIC ELECTRICITY
is sent through nerve and muscle, action in the nerve de-
pends on a change in the position of its component mole-
cules: that the change is in one direction only: and that
the current takes oxygen from the muscle. But in ordinary
nerve action though the two first probably occur, the oxygen
does not leave the muscle, but is consumed in it, and in its
new combination is carried away by the blood, and there is
apparently no electrolysis : and also in nerve action there is
no sign of return current. We should judge from this,
that ordinary nerve action is not electrical: for though
similar results are produced by natural nerve action and
electricity, they are produced dissimilarly.
VOLTAIC ELECTRICITY
CHAPTER VI
THE VOLTAIC PILE AND ELECTRODEPOSITION
THE first contrivance in the way of a battery was the voltaic
pile. It is a thing now quite gone out of use and not seen
except as a curiosity, but it exemplifies the principle of the
cell so clearly that it is well worth examining. We have
seen, or say tasted, how a piece of zinc and a piece of silver
with a damp tongue between them produced a current.
It is not necessary to use the tongue as the intermediary,
for any substance, that being porous can be made damp
throughout, does quite as well. So if we put a piece of
blotting paper wetted with salt water on a piece of zinc,
and a piece of silver on the paper, and join the metals with
a loop of wire, we have a voltaic cell perfect in the essentials
but not very strong. Volta's first instrument was a pile of
plates about four inches square of silver and zinc with moist
flannel above, placed in series one over the other and ending
with a zinc plate. In constructing these things thickness
does not signify : moistened paper with gold leaf on one side
and zinc foil on the other acts as well and strongly as thick
plates would do. In fact thinness is an advantage, as the
thinner the plates the more compact the arrangement and
the less the cost .
In the Clarendon laboratory at Oxford, there is a dry pile
made sixty odd years ago, and the terminals of it are attached
to two small bells, between which is hung a brass ball to
swing between them and ring them alternately, and it is
no doubt doing so still. Zamboni devised a pile in which
several thousand round bits of paper, with zinc foil on one
39
40 VOLTAIC ELECTRICITY
side and binoxide of manganese on the other, are placed
on one another in a glass tube : the resistance is very great
as the paper gets its moisture from the air, but the enormous
number of cells for each zinc, paper, manganese, forms a
cell gives it great electromotive force, so that it will give
small sparks.
Volta considered that the action of his pile was due to
the contact of the metals, hence his arrangement of two
metals at the ends. In the cell, as we have seen, the wire
from the copper is positive and that from the zinc negative,
while in Volta's pile the terminal zinc is positive and the
terminal silver negative: this seems an upsetting of rules:
but there is no such inversion, because the end pieces are
not parts of the battery, but merely conductors like the
wires of the common cell, and the plates that are really
the terminal electrodes are the zinc below and the silver
above and which are inside the terminal plates.
Volta in pursuit of his theory examined many metals and
arranged them in a list according to their apparent inter-
actions: but in fact the differences that he ascribed to
mutual electrical potential were due to chemical potential :
sodium the easiest to oxidize being at one end of the series,
and graphite the most resistant at the other. As no two
metals are alike in this chemical reaction, any two brought
together with moisture between them will show electric
action, and they will do this in air when they seemingly
have no intervening moisture, which may have led Volta
to form his opinion, but they act because of the electrolytic
action of the layer of condensed air between 1 them, and it is
not on account of their contact that they can act, for there
is no such " result if they are brought together in vacuo,
in dry hydrogen, or nitrogen." And this very action is a
source of weakness in the pile as it tends to produce a re-
verse current polarization in fact. If any two metals are
cleaned, and heated to drive off condensed gas or vapour,
VOLTAIC ELECTRICITY 41
and are then placed in contact in any simple gas, there is no
action : and if they are so prepared and placed in air, there
is for a time no action until they have recondensed on them
a fresh film of liquid air.
In investigations connected with heat there is an instru-
ment used a heat detector called the thermopile, which
is made of small rods of bismuth and antimony placed in
a bundle with their alternate ends soldered together : a very
slight change of temperature, such for instance as would be
made by moving to stand in front of the instrument at six
feet away from it, will send a current of electricity through
it: but though the metals have great potential differences
and their ends constantly touch, there is never a sign that
any action takes place on that account. So we may reject
the contact theory and stick to the chemical, which is, that
one metal has more potential than another because it is more
easily acted on chemically.
The examination of the action of electricity in electro-
deposition will not give us much increase of information,
but the processes are of some interest and we may as well
glance at them to make sure that there is nothing in them
contradictory to our deduction that electricity is a wave
in the electrolyte.
There are three definite processes, which are all of com-
mercial value and require care in application, with know-
ledge of appropriate solutions and of the strength of the
currents to be employed electroplating, electrotypiiig,
and electrorefining. In all of them the principle of the
process is the same: a plate of the metal to be deposited
is connected to the copper wire of the battery, and is im-
mersed, as the anode, in a bath of solution of some salt of
the metal: and in the same bath, as kathode, the objects
to receive the deposit are placed and connected by wire with
42 VOLTAIC ELECTRICITY
the zinc of the battery. The current acts on the salt mole-
cules, separating their metal and acid components, and
deposits the metal molecules on the objects put to receive
them, and drives the acid to the metal plate which is con-
sumed away by it as fast as the deposit is made.
In electroplating what is desired is a thin and hard cover-
ing and the operation is therefore slowly conducted.
Gold, silver, copper, and nickel are the metals employed
to coat some baser metal, and of these, for merely ex-
perimental purposes of observation, copper is to be pre-
ferred, as it is at once the easiest to work with and the
cheapest.
Eight ounces of copper sulphate, two and a half ounces
of sulphuric acid, and a quart of water make a good bath :
and one cell is sufficient for the working. The object on
which the deposit is to be made must be cleaned thoroughly,
for the touch of a finger or the least tarnish will spoil the
coat. The thing should be washed in hot potash solution
and, if tarnished, 'passed through solution of potassium
cyanide : then rinsed and hung in the bath.
Only brass and the less oxidizable metals can be coated
in this way. For iron, tin, and zinc a first coating must
be given in an alkaline solution. This is made by dissolving
four ounces of copper sulphate in a pint of w r ater and adding
strong liquid ammonia till the sediment first thrown down
is dissolved : the liquid is then of a lovely dark blue : then
add solution of potassium cyanide until the colour has gone^
and then add as much more of this solution of cyanide as
amounts to about a quarter of what has been used : add water
to make the whole equal to a quart. Warm this to 140 F.
not more and use two cells in series to work it. As soon
as the articles are well covered, take them out, wash them in
water, and finish the plating in the other bath. In the
alkaline (ammonia) bath, there is a double displacement
of molecules which is so easily effected by the current that
VOLTAIC ELECTRICITY 43
the iron or other metal is preserved from corrosion, which
would certainly happen were it put unprotected in the acid
bath.
*****
In electro typing the object to be attained is the copy of
some medal, wood-block, or sheet of set up printing type,
and in every case the process is the same. Clean the face
of the article to be copied with potash water or benzine,
taking care to remove any ink or dirt that would interfere
with the sharpness of an impression (but not troubling to
remove tarnish or bronzing), and black lead it. Melt some
beeswax with sixteen per cent, of Venice turpentine and
three of plumbago: and keep this as hot as boiling water
for a quarter of an hour so that no water may remain
in it, for the least moisture would be sure to cause it to
crack : then spread it in a sheet larger than the article every
way : when cold press a copper wire into the edge all round
and twist the two ends together that they may be joined
presently to the copper wire of the battery : then blacklead
the upper surface of the wax and the wires : press the article
on the wax till it has given a perfect mould this will re-
quire a hydraulic press for large sheets. Now remove the
article and pass a hot iron over the back of the wax and over
such places round the edge as are not to be deposited on,
and again blacklead the face, and when dry pour a stream
of water over it to remove superfluous blacklead and hang
it in the bath.
The bath should be as strong as possible to begin with
and the current high, and the solution should be gently
stirred with a feather: afterwards the current should be
less. This insures a uniform first deposit followed by a
hard one. When thick enough (a hundredth to a thirtieth
of an inch) remove the wire, pour warm water on the copper
and the wax will come away : any that does happen to stick
wash off with boiling potash water : dry and lay face down-
44 VOLTAIC ELECTRICITY
wards, and cover the back with tin-lead foil sprinkled with
sal ammoniac, and heat the foil till it is melted : then pour in
the backing metal made of lead with five per cent, each of
antimony and tin added: and when cool trim as required.
For small objects the mould may be made of plaster of Paris
or of sulphur, but for large things these cannot be used as
they shrink too much: hot guttapercha may also be used.
In whatever way it may be done it is a troublesome business,
but very beautiful copies may be made in this way of very
precious articles, which also may be considerably damaged
in the process. Verb. sap.
In electrorefining the object is to get the pure metal as
quickly as possible. A plate of the common commercial
metal is used as anode and is consumed, its impurities fall
to the bottom of the bath, and the pure metal is deposited
on a plate of the pure metal used as kathode. A strong
current is used as it does not matter in what state the deposit
is made, whether spongy or hard.
For every sort of electrodepositing done on a large scale,
electricity is now supplied by steam motors which are much
cheaper than zinc batteries.
Copper as it is extracted from the ore is pure enough
for general use, but for a particular purpose, when a high
standard of purity is needed, the metal is usually got
electrolytically, when the arsenic and other impurities are
left in the solution.
The action in liquid is what is most often seen and studied
and it is supposed by some to be the sole method of electro-
lysis, but it may sometimes be forced on compound solids
which are conductors, and it decomposes them by means
of their water of crystallization in the same way as it does
the liquid electrolytes. Sir Humphry Davy discovered
VOLTAIC ELECTRICITY 45
potassium and other metals by this method. By placing
solid potash as the electrolyte, between a plate of platinum
as kathode, and a copper wire as anode, and sending a
current through the arrangement, the metal was disengaged
in little globules on the platinum, while the oxygen acted on
the copper.
It is electrolytic action also that causes the separation of
minerals in furnaces worked by heat and electricity com-
bined. Aluminium is extracted in this way. The oxide
that is clay is put in a brick furnace lined with carbon, and
between two bars of carbon through which a strong current
of electricity is sent : the heat is intense : the clay gives up
its oxygen to the carbon to be changed to gases, and the
aluminium separates pure. There are other electrical
methods of reducing aluminium and other metals, but all
are as evidently electrolytic and chemical as the above-
described method.
STATIC ELECTRICITY
CHAPTER VII
THE ELECTRICAL MACHINE
" WHEN two dissimilar substances are rubbed together
they produce electricity/' This was in a way known to
the ancients, who however lookedbn it merely as a curiosity,
and it was not till about 1650 that the first electrical machine
was invented by Otto von Guericke, who used a globe of
sulphur which was turned while pressed by bare hands, and
with which he was able to produce sparks. This was more
than a hundred years before Galvani had his first inklings
of what we call voltaic or galvanic electricity. The sulphur
was soon replaced by glass, and the form changed gradually
till it became a flat wheel of glass a disc of plate glass of
uniform thickness. Use was made of rubbers instead of
hands, and they also were improved till now they are leather
or silk cushions stuffed with hair and covered with an
amalgam of tin, zinc, and mercury, mixed with grease.
The plate pattern electrical machine is a circular piece
of thick glass, pivoted at its centre, and placed upright be-
tween two wooden supports rising from a broad base. The
pivot passes through the supports; and the cushions, which
are on both sides of the glass, are fastened to the supports,
a pair above and a pair below the pivot ; and at one end of
the pivot is the handle for turning the glass. On the oppo-
site side of the glass to the handle is an arrangement of
brass bars, or rather tubes, supported at the height of the
pivot on glass pillars fixed in the base : the principal parts
are two bars, parallel to each other, which are .called the
prime conductors, and they are placed so that one end of
46
STATIC ELECTRICITY 47
each is close to one edge of the glass ; and each of these ends
has fastened to it a bar which is bent so as to pass round
the edge of the glass and enclose it in a long U ; and the inner
sides of these bent bars have a number of sharp points
directed towards the glass but not touching it. The other
ends of the prime conductors which are furthest from the
glass are joined by a cross bar.
There are several precautions which must be observed
in using an electrical machine if we wish to produce anything
but perspiration and vituperation by working it. There
must be no dust on it. The insulating pillars, even if made
of glass, are better for being varnished with a thin coat of
shellac varnish. If the machine has been for long out of use,
it should be cleaned and have a fresh coating of amalgam.
The whole machine is better for being warmed to drive off
any moisture that may have condensed on it. And when
you have done all these things you may find that it will
not work because the weather is damp. It is indeed a
very uncertain machine and has been given up in favour of
influence machines which are much more reliable. We,
however, must not give it up until we have mastered what
we can of its mode and effect of action, a clear under-
standing of which will profit us much in our study of Static
or frictional electricity.
The following is the action of the machine. The glass
plate is turned by means of the handle and rubbing against
the amalgam on the cushions, positive electricity is developed
on the surface of the glass, and negative on the surface of the
cushions, in exactly the same way as these electricities are
developed when a glass rod is rubbed with a piece of silk.
The glass rod and its silk rubber are in fact a feeble electrical
machine, the glass carrying the positive and the silk the
negative charge.
If the whole machine, plate, rubbers, and conductors, are
well insulated, we can, by working the handle, create and
48 STATIC ELECTRICITY
store up, as we may say, a certain amount of electricity in
the machine, but however much we may labour there is a
limit to this amount, and we can store up just so much and
no more : but if we put the rubbers in connection with the
earth, a very much stronger electrification is at once given
out and continues to be produced as long as the plate is
turned.
The electricities produced by the machine are the same
as we had from the voltaic battery : the one, the positive,
accumulates in the conductors, and the other, the negative,
is stored in the insulated rubbers. When the rubbers are
connected with the earth, a great quantity of electricity
is stored in the conductors and gives strong sparks in escap-
ing from them. And if both rubbers and conductors are
connected with the earth, all the electricity we may produce
passes away and our labour is wasted.
In some works on electricity it is very explicitly stated
that the positive charge on the glass is carried by it till it
is opposite the collecting combs of the prime conductor,
and that then the points of the combs discharge on to the
glass plate the negative electricity of the conductor, and
so neutralize its coat of positive electricity, after which the
plate goes on towards the rubbers free to accept a new charge :
meantime the positive electricity of the prime conductor
is repelled to the end furthest from the glass.
There seems to be something wanting in this explanation,
and when it is added, as it sometimes is, that the current of
positive electricity flows from the ground for the charging
of the disc, it only adds to the incomprehensibility of the
whole story.
No one can doubt that electricity is produced by the
rubbing of the glass disc, for it is produced in considerable
quantity even when the whole machine is insulated from the
ground. Also it is certain that positive and negative elec-
tricities are produced as we can collect the one from the
STATIC ELECTRICITY 49
conductor and the other from the rubbers. And also it is
certain, that when the rubbers are connected with the
ground, positive electricity can be continually drawn from
the conductors, and the negative electricity continually
flows into the ground, as any galvanoscope will show us.
No doubt at starting, the positive electricity of the prime
conductor is driven to its furthest part, and the negative
attracted towards the glass, but the whole of this negative
electricity must be used up at the first turn of the machine,
and no more can be got off the conductor to neutralize the
positive charges produced by succeeding turns. And as
to the wire carrying positive electricity from the earth, the
disc does not want any from the earth, as it is -making it for
itself, and " positive and negative electricities are generated
in equal quantities by friction/' and the earth wire is merely
a means of getting rid of the negative electricity which has
been produced by the machine.
The old idea that the points of the collecting combs absorb
the positive electricity from the glass plate seems more
reasonable, for sharp points both collect and discharge elec-
tricity. It is certain that if you ornament the knob of your
electroscope with a needle, it is completely discharged in
a few seconds ; but also, if you electrify a glass rod, and pass
its length over the needle point at about half an inch from
it, the rod will be more thoroughly discharged into the
electroscope than it would be by contact at any one point
with the needle. This experiment must be done slowly
or the gold leaves will be broken.
As our inquiry is more particularly directed to the dis-
covery of what electricity is, it does not perhaps very greatly
signify to us in which of the two ways the conductor gains
its electricity, but still one does not like to leave a point
doubtful, and when one sees a brush discharge coming from
a point fixed on the prime conductor, and notes the vehe-
mence of it, and the time of its continuance, which is as long
4
50 STATIC ELECTRICITY
as the machine is worked, it does not appear possible that
all this discharge can come from the conductor alone and
that none of it comes from the glass disc : on the contrary,
one is convinced that the opinion of the majority is the right
one, which is, that it is produced by the working of the
machine and does certainly come from the glass, and must
be collected by the combs.
We will agree then that the electricity is produced by
the rubbing of the glass and rubbers, just as certainly as it
is by the rubbing of the glass rod by the silk handkerchief.
The amalgam rubbing the face of the glass produces positive
and negative electricities which are separated, the one to
be carried away by the glass and the other by the amalgam,
and that on the glass is taken up by the collecting points
and is driven on to the conductor with such violence that
it breaks into long sparks and brushes to get free. It is
plain from this, whatever else may happen, that some-
violent action is taking -place where the rubbers touch the
glass, and as " friction exerts a chemical influence, even
silicious minerals such as mesotype, basalt, and feldspar,
becoming partly decomposed and giving off a portion of
their alkali in a free state/' we will try to find out whether
any sort of chemical action can occur.
Whatever action occurs, is plainly brought on by friction,
and friction produces heat (they say) by the violent mechani-
cal motion of the molecules causing vibration in the sether.
This is a very easy explanation, but the production of both
heat and electricity may be explained in another way, and
that is, that the mechanical motion forces the surface mole-
cules into chemical combination with the condensed oxygen
on the surfaces, and that this combination produces the
heat and electricity.
Considered thus, we see that the rubbers have taken the
place of the zinc in the voltaic cell, and the glass that of the
copper. The amalgam is acted on and to it the negative
STATIC ELECTRICITY 51
current goes, the glass is not acted on and carries away
the positive electricity. It is by the oxidation of the amal-
gam that the electricity is produced, and the oxygen is pro-
vided by the condensed gases of air on the surface of the
glass. It is as much a chemical action as is the action in
the voltaic cell. The amalgam is the oxidized anode, the
condensed air the decomposed electrolyte, and the glass
the kathode unacted on. The electromotive force of the
voltaic cell depended on the weak unaided force of chemical
affinity to produce it, and it was weak accordingly: in the
machine, muscular force assists chemical affinity by driving
the units violently together, and the consequence is a violent
electromotive force. It is like the increased action pro-
duced by bellows on a fire, or by a rod in stirring a solution.
Still, though we may be convinced on these subjects, there
are others who seem to think that the electricity is not
produced by the friction of the rubber on the glass, but
that it is, as it were, pumped out of the ground and merely
divided into positive and negative by the machine: and
these would say, in support of their theory, that the fric-
tional electricity is not in proportion to the friction: for
two pieces of the same material, smoothness, and tempera-
ture may be rubbed together to all eternity and yield no
electricity. If friction produced electricity alone, this
would be a serious objection: but, as everyone knows,
heat is plentifully produced by such rubbing : and the more
alike the objects rubbed together are, the more the heat
and the less the electricity. We must also remember that
any motion can only reproduce an equal amount of motion,
and if it produces the motion heat it cannot produce
that other motion electricity: and also that metals of
similar potential are similarly acted on, and therefore if they
produce any electricity it is mutually cancelled as fast as
it is made.
When we bring these facts into consideration they show
52 STATIC ELECTRICITY
that the want of proportion between friction and electricity
gives us an additional argument in favour of the chemical
theory rather than one against it, and confirms the idea that
the action between the surfaces is electrolytic . And apparent
exceptions are not difficult to answer, for if two good unlike
conductors rubbed together give apparently little heat
or electricity, it is because the heat flows through the
material and is lost to us and the electricity flows away over
the surface, and even if we take the trouble to insulate the
objects it escapes at every point and angle. And if two
unlike nonconductors rubbed together show ardent heat at
the surfaces rubbed, it is because the heat cannot escape by
conduction, and if they show little electricity it is because
their material is not oxidized easily, and wanting chemical
action electricity is also wanting. Certain unlike bodies
rubbed together produce as we see with our glass rod and
silk electricity, and in this case the silk has, after the
rubbing, a peculiar smell: some part of the silk, or some-
thing associated with it, has been oxidized by the condensed
gas on the rod : pass the rod through a clean frame to drive
off the gas coating and no electricity is produced however
much you may rub it.
The above makes it plain why one of the bodies in the
machine is a conductor and the other a nonconductor, that
the one must be oxidized and the other unchanged. Being
very different in potential they produce more electricity
than heat : the negative electricity is not wanted and flows
over the conducting earth wire to the earth: the positive
remains on the face of the nonconducting glass till it is
picked up by the collecting combs. The further apart the
two materials are in conductivity and the further apart
they are in oxidability, the more the electricity and the
less the heat produced. So proportion of friction to
quantity of electricity has no bearing on the subject.
The reason for using a nonconductor as the material for
STATIC ELECTRICITY 53
the plate of an electrical machine is that the electricity
may not escape as it would do from a conductor, or spread
itself all over the surface as it would do on an insulated
conductor, in either of which cases all the action would be
annulled. The charge on the glass remains on the spot on
which it was placed, and does not move from it till it is
picked up by the collecting combs.
STATIC ELECTRICITY
CHAPTER VIII
THE CHEMICAL ACTION
THE oxidation of the amalgam, or some other chemical
action, is absolutely necessary to the production of elec-
tricity by friction. Wollaston found that the machine
would give no electricity when worked in atmospheres of
hydrogen, nitrogen, or carbonic acid. There is plenty of
oxygen in carbonic acid, but its attachment to carbon is
evidently greater than its affinity to amalgam, and, if you
care to try the experiment, you will find that neither mer-
cury, zinc, nor tin, shows any trace of oxidation if covered
with carbonic acid gas. We might try experiments with
other gases, to the damage of the machine probably, but
we do not need them, sufficient has been done to give us
enough evidence for what we want to prove. We see that
the machine produces electricity when the amalgam is
chemically acted on, and will produce none when the supply
of chemically acting material is cut off, so we may conclude
that chemical action is a necessary part of the process, and
that it is no theory but a fact that is borne out by every
experiment.
" In electrical machines the oxidation of the amalgam
by the friction is essential: the development of electricity
falls off when amalgams of difficultly oxidizable metals are
used: and no electricity can be obtained from a machine
worked in pure carbonic acid gas/'
To produce the oxidation of the amalgam it is necessary
also that there should be some action in the film of liquid air
which is on the glass, and which is acting as electrolyte.
54
STATIC ELECTRICITY 55
We cannot suppose that this is a chemical process, because
the oxygen and nitrogen that make up our air are not com-
pounded in any way but merely mixed, and this is no doubt
their state whether they are gaseous or reduced to liquid.
Still the molecules, touching one another, must have some
attraction of cohesion towards each other, making them
cling together, in the same way as we see that the molecules
that form a drop of water must, with some force, cling
together to be able to keep the form of a drop: indeed
" molecular cohesion between neutral molecules at very
minute distances may be very great, almost indistinguish-
able from chemical combination/' and as the average liquid-
air molecules are two and a half times heavier than the
three molecules that form a compound molecule of water,
they must cling together with one hundred and fifty per
cent, more force than the water molecules do. It is on
account of this greater cohesive force that we find so much
difficulty in removing the film of condensed air from surfaces
in comparison to the removal of a film of water, so we may
conclude that the molecules of the liquid air cling together
with such force as to give the electromotive force something
to do some body with opposition to react with and produce
an electrolytic movement some allied molecules to be
separated so as to make new alliances.
The meeting of the molecules of oxygen and amalgam,
forced together, produces strong vibrations of electromotive
force, which travelling through the liquid air compel, with
each throb, the oxygen molecules one step towards
the amalgam, and the nitrogen one step towards the
What happens when the nitrogen arrives at the glass ?
Is it given off into the common air ? Nobody seems to
know or to have given this item any thought, probably
because the thought of such action occurring has not
occurred to them, though it is plain that it must happen.
56 STATIC ELECTRICITY
Then again what happens when the electromotive force
reaches the glass ? Nobody knows, but for certain it is not
changed to heat, nor dispersed, nor annulled, for it remains
active in some way on the surface of the glass for some
time, and can be transferred to the conductors by th&
collecting combs.
Having arrived at this impasse let us retire and consider
something else. Let us consider the other various methods
in which this sort of electricity is generated.
" In forcing liquid through a porous substance a current
is produced/' We might say, if we were disbelievers in
the necessity of chemical action for the production of
electricity, that there is none of it here : the stuff comes out
just the same stuff as it went in. " Forcing water through
sulphur with a pressure of an atmosphere (15 Ibs. to the
square inch) produced a potential difference of over nine
volts. When forced through porcelain, the difference was
about a twenty-seventh part as much; and when through
bladder only about one nine hundredth/' The pressure
would of course drive the water but slowly through the
apparently solid impervious sulphur, faster through the
porcelain, which we know is pervious to moisture when
unglazed, and fastest of all through the bladder : and owing
to the pressure being unchanged and the resistances and the
velocities due to them different but equal in aggregate, the
friction in all the cases would amount to the same. It is
then something else than friction that occasions the great
difference in electrical out-turn: and as it is not mechanical
friction it must be molecular disturbance.
The porous passages of the sulphur are much smaller
than those of the porcelain and bladder, and we must assign
the greater action to the greater constriction of these
passages. The oxygen and the hydrogen of the water mole-
cules are severed and recombined as they are forced through
these narrow ways, and this is all that is needed for the
STATIC ELECTRICITY 57
production of a current. Recombination, as we have seen,
is what produces electromotive force.
A jet of steam issuing from a boiler produces electricity
by the friction, it is said, of the steam against the orifice.
This action of steam was discovered by accident. An
engine-man happened to put one hand on the lever of the
safety-valve of his engine, while his other hand was in a jet
of steam that came through a crack in the cement fastening
the valve to the boiler, and he received a severe shock. Sir
W. Armstrong followed up the investigation from this initia-
tive, and for the purpose of his experiments had a boiler
made, which, with its furnace, was supported on glass legs.
With a pressure of a hundred pounds to the square inch,
a plentiful supply of electricity was produced when the
steam was allowed to escape from a jet.
" The body of the boiler gave negative, and the jet of
steam positive electricity/'
" After working for some time the conditions changed:
the boiler became positive and the steam negative."
" Washing the boiler out with water made no change after
this, but washing with potash and water restored the first
state, and with a little potash in the water in the boiler the
quantity of electricity was very much increased."
" By the addition of a little nitric acid, or of nitrate of
copper, to the water in the boiler, the steam became negative
and the boiler positive, and washing out the boiler with
dilute nitric acid had the same effect."
" Oil of turpentine changes the electricity of the steam
whatever it may be, and so also with olive oil."
" When the electricity of the steam is carried to the earth,
the production of electricity is much increased and the
discharge from the boiler much stronger: sparks fifteen
inches long being produced."
" When the steam was negative through the addition of
nitric acid to the water, the putting of a wooden tube inside
58 STATIC ELECTRICITY
the copper jet changed the steam to positive and the boiler
to negative/'
" With moist compressed air substituted for steam, the
jet of air was positive and the container negative, as with
the steam and boiler/'
" With dry air or dry steam no electricity was produced."
It is plain that the action is between the moisture and
the metal jet, and it is easy to see the likeness of this steam
electric machine to the ordinary frictional machine and
to the voltaic cell. As it was first constructed and used,
the copper jet was the anode, and represented the amalgam
of the frictional machine and the zinc of the cell : the steam
was the kathode and stood for the glass and the copper : and
the water, condensed from the steam on the jet, was the
electrolyte the same as in the cell and stood for the con-
densed air on the machine.
While the steam jet was positive, the boiler represented
the earth in the electrical machine: when the jet turned
negative it became the prime conductor.
The water molecules brought into violent contact with the
metal of the copper jet combined with its surface molecules,
and by this combination produced the waves of electro-
motive force which passed from the copper anode through
the water electrolyte to the steam kathode. The oxygen
of the water combines with the metal to oxidize it and the
hydrogen goes free in the steam. It would be interesting
to confirm this by practical experiment, but it would be an
expensive business as these steam machines are not made
now.
Water is a necessity as Faraday discovered, and neither
dry air nor dry steam has any electrical effect though they
produce heat in quantity by friction. "-If the jets were
allowed to become so hot that they condensed none of the
steam as it passed through them, there was no electricity
produced until they were cooled down again/'
STATIC ELECTRICITY 59
When the whole steam machine was insulated, the steam
could only get rid of its electricity by means of the steam
jet in a sort of brush discharge, and the boiler discharged
its electricity by " sparks and coruscating trails/' and no
doubt much electricity was wasted and turned to heat
working against the resistances. But when the steam was
put in connection with the earth, by letting it blow against
a collecting comb with earthed wire, and its electricity
had found a free road of escape, the whole effect was greatly
increased, and long dense sparks were given off from the
conductor of the boiler. This reminds us of the similar
conduct of the glass electrical machine before and after
its rubbers were connected with the ground.
It is not at all necessary to insulate the boiler of these '
machines: connected with the ground, like the amalgam
in the other machines, it would certainly act better : positive
electricity in large quantity can be drawn from the escape
steam of railway engines which are in no way insulated,
and which act the part of anode: but it was found to be
much more convenient to take the electricity from the
boiler, and in order to do this it must be insulated.
The addition of potash to the water increases the effect,
because the potash solution makes a better electrolyte than
the pure water, giving up its oxygen to the copper more
freely than the water does.
The action of the nitric acid was to reverse the action,
probably because its vapour had more affinity to the steam
than to the copper, and in this way changed the steam into
anode.
Oils cannot be said, when hot, to have any chemical
action on metals which they preserve from oxidation; and
certainly they are not prone to alliance with water, but
their vapours may have some interaction with steam,
and if so would cause the steam jet to become the active
terminal, that is, the anode. Faraday thought that the
60 STATIC ELECTRICITY
change caused by the addition of oils was owing to the
globules of water having a film of oil upon their surfaces,
which coating received the friction and so prevented the
water from having any. But this conveys no explanation
to us who consider that friction is of no account in this
matter except as an excitant to chemical action, and in this
case the chemical action was not suppressed but changed.
After working for some time the action of the machine
is reversed and the steam becomes negatively electrified.
As the water boils away the impurities that it has in itself
and that it has derived from the boiler would, perhaps by
long heating, be dissociated into their component molecules,
and the vapours of their acids would be carried up with
the steam to act in the same way as the vapour of the nitric
acid acts.
It was found that the form and substance of the jet had
a considerable effect on the results. In the case of the
wooden tube inserted in the copper jet, it is not difficult
to find the reason for the increase of activity, for now the
steam is no longer kathode but merely a conductor, and the
working parts consist of copper anode, water electrolyte,
and wood kathode: and the wood being so much more
intimately in contact with the water than the steam was,
is the cause of the improvement.
The steam electrical machine was found to be very
powerful, but it was distractingly noisy, and covered every-
thing near it with the moisture of condensed steam; but
even if it had not had these disadvantages it would not be
used now, as all electrical machines are shelved in favour
of electromagnetic motors.
" In a volcanic eruption, electricity is generated by the
friction of the steam against the walls of the vent; this
produces the thunder storms that accompany eruptions.
The steam condensing in the higher cold air falls as heavy
rain." In volcanic eruptions Nature assumes a position
STATIC ELECTRICITY 61
sufficiently strong to prevent even the most inquisitive
from poking their noses into her business, and what happens
in these cases will no doubt always be matter for conjecture,
but so far as we are concerned we have gained sufficient
knowledge to assume that there is always plenty of chemi-
cal action going on in the eruptions, and more than enough
to provide for all the electrical phenomena that have been
found to occur, and to produce mephitic vapours for the
suffocation of hundreds of unfortunates as well. We can
only theorize about these cases, but probably it is not the
friction that directly produces the electricity, but the inter-
action of the chemical affinities of the substances ejected and
forced into combination by friction that is produced by the
eruptive force: and the electrical force so produced is prob-
ably much of it dissipated in the earth: and the thunder
storms are probably produced by the electrified diist which
is carried up with the steam.
Apparently friction has just the same effect as the stirring
up together of chemically interactive substances would
have : it brings the different molecules more quickly together
and so hastens their chemical union. And the cause and
course of production of the electric force in statical elec-
tricity is evidently the same in every respect as in voltaic
electricity. It is a joint action of chemical combination
with electrolytic conduction. The electricity is due to the
action of the machine, and has nothing to do with external
influences, and the action of the machine is due to oxidation
of the amalgam. Do not let us forget this, and also that
the production of. the electricity is made possible by the
use of particular substances and by the particular arrange-
ment of the machines.
THERMO ELECTRICITY
CHAPTER IX
ACTION OF HEAT AND CURRENT ON JUNCTIONS]
THERMOELECTRICITY is the most difficult part of our sub-
ject: difficult to understand and very difficult to explain
clearly: we must therefore attack it carefully and with
patience.
If two metals form a circuit and one of their junctions
is heated, an electric current is set up. This was discovered
by Sebeck in 1821, and great hopes were raised of the
application of it to some useful purpose, but the amount of
electromotive force produced is so very small that no
economical use can be made of it.
There is, however, a small instrument made on this
principle, named the thermopile, which is very useful to
heat investigators when observing very small changes of
temperature. It is made of small bars of bismuth and
antimony joined at their ends but separated everywhere
else by some nonconducting substance: they are packed
in a cubical case which is open at opposite sides where the
joined ends are exposed. The bars are so arranged that,
if they were stretched out in one long line, they would form
a continuous conductor of alternate pieces of bismuth and
antimony; any effect, therefore, that is produced by the
difference of heat of one set of junctions to that of the other
is cumulative like the electromotive force in a series of
voltaic cells. Wires from the first bismuth and the last
antimony complete the circuit and show any electromotive
force produced by its action on a galvanometer which is
placed in the wire circuit.
62
THERMOELECTRICITY 63
This last instrument (the galvanometer) is a couple of
equally magnetized needles reversed in direction to each
other (North above South) and suspended by a fibre in
such a manner that the lower one is within a coil of wire
which passes over and under it and parallel to it while it
is at rest. When a current passes through the coil, the
ends of this needle are driven out from the coil, in one
direction or the other, according to the direction of the
current.
The thermopile, when in use, is turned with one face to-
wards, or touched with, the object of which the temperature
is to be tested, and if there is any difference of heat made
by doing this between the two faces of the pile, the instru-
ment records it by its effect on the galvanometer. Very
small and very quick variations of temperature are detected
by this instrument, that would pass quite unnoticeable in
observation with a thermometer. Passing the hand, for
instance, in front of one face of the instrument, and an
inch away from it, will usually send the galvanometer
needles at right angles to the wire coil.
Another application of this effect of heat on junctions
of dissimilar metals was proposed, but whether found
efficient or not is not known to the writer. It was an in-
vention to find the temperature of borings or other inacces-
sible places, by lowering into them one of the joined ends
of two wires of copper and iron covered with insulating
material, whose other joined ends were in a bucket of water
in which was a thermometer: a galvanometer was also in
the circuit on one of the wires. The water in the bucket
was to have its temperature changed until the current
ceased to affect the galvanometer, when the temperature
of the hole would be the same as that of the water as shown
by a thermometer.
There have been other thermoelectric machines made
that we need not describe, as they soon became inefficient,
64 THERMOELECTRICITY
but one of them used materials which we should notice : they
were iron and galena. Now iron and lead make a weak
couple of less than a sixth of the activity of a bismuth and
antimony couple, while a couple of iron and galena (which
is sulphide of lead) is much stronger than one of bismuth
and antimony. We should remember this when we
come to inquire into the causes of production of this
force.
If the heat at one junction of a couple circuit is constantly
increased, the current is increased up to a certain point:
then decreases till it comes to nothing : and with still higher
heat is reversed, flowing in the contrary direction to that
which it had before. Thus, in an iron and zinc couple, with
one junction kept at 50 C., and the other increasingly
heated, the current runs from iron to zinc and increases
up to 200, after which it decreases till the temperature
at the hot junction is 400, and then the current reverses
and passes from zinc to iron.
If a current is sent through a conductor made of two
dissimilar wires joined end to end, the junction is heated
or cooled according to the direction of the current and the
material of the wires. For instance if they are bismuth and
antimony, and the current is sent from bismuth to antimony,
the junction is chilled: if sent the other way it is heated.
This is called the Peltier effect. If a wire is hotter at one
end than at the other, it will be more heated by a current
sent through it in one direction than if sent in the other.
This is called the Thomson effect.
With some metals, increase of heat causes the difference
of heat produced by the current to be increased, while with
others the difference decreases. Thus copper the hotter
one end is made than the other, the greater is the thermo-
electric effect, that is the greater the difference of electrical
heat for each degree of added combustion heat: while in
iron the electrical heating effect decreases the hotter the
THERMOELECTRICITY 65
end is made, the more the fire heat applied the less the current
heats the iron in proportion.
The measure of heat generated in a wire by any electric
current is current squared multiplied by resistance = C 2 R :
and when one end of the wire is made hotter by fire than
the other end, there is an additional heat added or subtracted
according to the direction of the current, the measure of
which is current multiplied by a force S = CS, in which S is a
variable, increasing or decreasing according to the metal used :
increasing with increase of heat in copper, and decreasing
with increase of heat in iron, and of different energy in every
other metal. The total heat, then, of any wire heated at one
end and heated also by electricity is, fire heat +C 2 R + CS.
So long as the fire heat continues to increase, the CS heat
continually increases in one case and decreases in another.
" In iron a current flowing from a hot to a cold part ab-
sorbs heat, in copper a current flowing from a hot to a cold
part evolves heat." These two metals show well the
different production and different energy of S, which differ-
ence must be due principally to the different powers that
these and other metals have of absorbing heat, and of
radiating and conducting it. Iron absorbs heat and radiates
it better than copper, while copper conducts heat more
than six times as well as iron. For all these reasons the
surface of a longer part of the wire is acted on in the copper
than in the iron: and it is this surface action that produces
the force S. So in copper more and more of the force S is
produced as the heat is increased, owing specially to the
quick conduction : while in the iron, due probably specially
to the greater radiation, a continual less addition of surface
is brought into action and the force S shows a less increase
in proportion to the increase of heat.
The line representing the force S is straight in most metals,
but sometimes it takes unexpected curves in the higher
temperatures.
5
66 THERMOELECTRICITY
The following is a list of some metals giving their thermo-
electric powers when coupled with lead which is put as
neutral, because the heating of a lead wire produces no S
effect. Those metals in the list that are above lead are said
to be positive in action to it, and those below negative, and
each is positive to the one below it. The numbers represent
microvolts per degree centigrade for each metal compared
with lead.
Bismuth, 89 to 97 Platinum, 0-9
Nickel, 22 Copper, 1-36
German Silver, 11-75 Zinc, 2-3
Lead, Iron, 17-5
Antimony, 22-6
" A very little impurity makes a great difference in the
thermoelectric power of metal, and some of the metallic
sulphides, such as galena, exhibit extreme thermoelectric
power/'
When a current is sent from bismuth to antimony cold is
produced: and conversely, when it flows from antimony to
bismuth heat is produced. Silvanus Thompson says:
" It is clear that if bismuth is positive with respect to anti-
mony, any current that may be caused to flow from bismuth
to antimony is aided by the electromotive force of the
junction: whilst any current flowing from antimony to
bismuth will meet with an opposing electromotive force.
In the latter case the current will do work and heat this
junction: in the former the current will receive energy at
the expense of the junction which will give up heat."
Our object is to discover what causes one metal to be
positive to another and what produces the electromotive
force S.
We must always remember that heat means the contrac-
tion of molecules. In the oxyhydrogen flame, nothing
happens but the combination of two volumes of hydrogen
with one volume of oxygen to produce, not three, but only
THERMOELECTRICITY 67
two volumes of water vapour: and it is this 33-3 per cent,
contraction that produces the tremendous heat. In the arc
light it is not the electricity that gives the heat : the vibra-
tions of electricity are not heat vibrations: the work that
the electricity does is to detach the molecules of carbon as
carbon gas: they combine with the oxygen of the air, one
volume of carbon gas to two volumes of oxygen, to make,
not three, but only two volumes of carbonic acid gas, and
it is this 33-3 per cent, contraction that gives the tremendous
heat. The light is due to carbon gas molecules that have
failed to meet with oxygen, and contracting become incan-
descent charcoal.
. If there is heat in a junction of two metals from a current
passing through it, it is because the current has assisted
in the association of molecules, which, by the cohesive
power of their mutual embrace, have contracted and given
out heat. And if the current has produced cold, it is be-
cause the current has assisted the dissociation of molecules,
which released from mutual cohesion expand and require
heat to do so.
The following is an explanation that holds good for
several couples, such as bismuth, copper, or silver, with
zinc, or iron, or antimony; and zinc, or iron, with antimony;
but does not explain bismuth with either copper or silver.
There are, however, a number of incidental actions which
complicate this matter. Similarity in oxidating power:
difference of specific gravity which would make a difference
in the amount of air condensed on the surfaces and in its
density and activity : difference of conductivity which would
cause less heat to be produced on one of the surfaces : heat,
however produced, which would make a difference according
as one substance was more absorbent of heat than another :
molecular arrangement would no doubt also make a differ-
ence ; crystallized selenium, for instance, is about a thousand
million times more resistant to the electric current than iron,
68 THERMOELECTRICITY
and about forty-five times more active in thermoelectric
action. The subject needs further investigation, and the
explanation given further on is a tentative one, but probably
points to the main cause of the action. It is founded on the
difference of oxidizability of metals, which was, as we
learned, the principal cause of difference among them in their
power to produce voltaic electricity and static electricity,
and hitherto we have not found any production or transfer
of electricity that does not depend on chemical action.
This explanation we will consider in the next chapter.
With regard to the force S, it appears to depend in the
first place on the effusion of the metals: those metals that
have little effusion showing no force S : and in the second
place, for its varying action, on the conduction, radiation,
and other properties of the metals.
THERMOELECTRICITY
CHAPTER X
CHEMICAL ACTION
WHEN a current is sent from bismuth to antimony, it pro-
duces heat, and sent in the opposite direction, cold. The
faces of the metals are covered with liquid condensed air
with which their surface molecules combine slowly as oxides.
The current hastens this action, and besides sets up an
electrolytic tide of decomposition and recomposition in
which the oxygen molecules are carried across the junctions.
Now the bismuth oxide, Bi 2 O 2 , has two molecules of oxygen,
and the antimony oxide, Sb 2 O 3 , has three. When there-
fore the current flows from the antimony to the bismuth, a
slow counter current of molecular exchange flows across the
junction, and the two oxygen molecules from the bismuth
pass back across the border to combine with the antimony
which has just released its three: they do not satisfy the
antimony, which takes an additional molecule from the air,
and by the contraction of this molecule when it enters into
combination, heat is produced. When the current comes
from the other direction, three oxygen molecules pass across
from the antimony to the bismuth, which requires but
two, arid one of the three, being released, expands, and
requiring heat to do so, the junction is chilled.
It is plain that the above action may be complicated
by differences of specific gravity, of conduction, heat action,
and molecular arrangement, but besides all these there is
another action which has probably much to do with the
production of thermoelectric force: and that is the separa-
tion of the surface molecules from solids in the same way
69
70 THERMOELECTRICITY
as the water surface molecules separate in evaporation.
No name seems to have been given to this action of solid
surfaces, but M. le Bon has called their vaporous emanations
effluves, and to distinguish this evaporation of solids from
evaporation of liquids, and to save repeated explanation,
we will, in these chapters, call it effusion, which according
to the dictionary means dispersion as well as a pouring out.
Nobody knows anything about this effusion beyond this,
that it must be very slow and difficult in some substances,
and rather quick, easy, and plentiful in others. Copper and
brass seem to be very durable when exposed to ordinary
influences, but if you rub either of them with a finger you
will produce an odour, and you can say with certainty that,
whatever else may have happened, some of the surface
molecules of the metal have left it and combined with some
extraneous substance to form a vapour. On. one occasion
somebody collected some tadpoles to experiment with, and
to avoid crowding them they w r ere put into water in two
basins, one of which happened to be made of brass: the
next morning those in the brass basin were dead, those in
the other basin lived for several days: the effluves of the
brass had made the water poisonous for the tadpoles, but
no smallest trace of the metal could be found in the water.
It has also been found that bacteria are destroyed in water
kept in a silver or brass jug.
It is probably entirely owing to effusion that metals con-
duct at all after their condensed air coverings have been
driven away by heat. The effluves, combining with
oxygen as they expand on the surface, provide a feeble,
chemically active coating that allows of the passage of
some current. And it is probable also that this effusion
provides the molecules that combine with the condensed
air on the surfaces of cold conductors, and which cause
resistance by taking from the current the work needed for
their combination. For resistance is the conversion of
THERMOELECTRICITY 71
electrical motion to some other motion, such as heat,
light, or chemical change. Heat and electricity both hasten
effusion.
Looking at the list of metals given, with their thermo-
electric powers, we see platinum, lead, and copper close
together, and gold and silver should follow platinum.
These are all very lasting metals. Even lead, though it is
so soft, lasts for many years; the oxide which so quickly
forms on it appears to have a preservative effect. It
would seem as if these metals held their neutral position
with regard to the thermoelectric force because of their
want of activity in effusion : and as if their want of effusion
was due in some of them to their slowness of oxidation, and
in others to their quickness and their protection by their
coats of oxide. As regards the oxide forming a protection,
Messrs. Bone and Wheeler, in a series of experiments,
found that " with metals that do not oxidize, and with
materials already oxidized, excess of oxygen produces no
action . . . with clean copper the composition of water
from the gases H 2 is six times as fast as when it is oxidized
on the surface."
There are some examples of the thermoelectric power
which are produced by modifications of the process that we
described in the last chapter, which we will now examine
and in which we will find that chemical action is evidently
the cause of the result.
" A warm body is negatively electrified when rubbed
against a cold body of the same material/' The surface
particles, that is the effluves of the warm body, assisted
by their heat, are more ready to combine with the condensed
air skin than those of the cold body are, and the moderately
heated air skin is also more ready to act : and therefore the
warm body being the more active member, with higher
72 THERMOELECTRICITY
potential, becomes the anode: the condensed air is the
electrolyte, and the cold body the kathode. The friction
brings the combining molecules together quickly and
forcibly, but any heat produced by the friction is a waste
of power so far as the electricity is concerned.
: ' The interruption of circuit between the ends of two
bars brings them to a white heat. The heat is entirely
local and disappears when the bars are joined. The heat
is caused by something that happens in the air or aether
between the ends/' The aether may be left out of the
question, as electricity does not here produce heat directly
through action with it: it is the interruption in the con-
ductors that causes the heat. The current flows to the gap
and finds, instead of the good conductor it has used so far,
a layer of gases with enormously greater resistance. It
throws its waves on to this resisting medium, the molecules
of which transform many of these electrical waves to heat
waves, which, by expanding the molecules, bring them to a
condition to combine chemically, with a further production
of heat on account of the combination. It is a violent
combustion of the air as in the lightning flash. This mode
of producing local heat is now constantly used for " electric
welding/' and also for removing the temper from a spot
in a mass of steel where a hole has to be bored. It is very
useful for this sort of work, as the heat is confined to the
spot where the conductor and the steel meet, and is not
spread as it would be by a fire. Steel plates for armour-
clads have sometimes to be heated in this way for a bolt
to be inserted, or a bar can be added by merely sending
a current through the bar and the plate, and also pieces
can be cut out of metal slabs in this way. There are some
slight objections to the process, and it will probably be
superseded by a new acetylene-oxygen apparatus, or an
improved oxyhydrogen blowpipe lately brought out, both
of which blow away all oxide and leave a very clean cut.
THERMOELECTRICITY 73
" If the ends from the positive and negative wires from
the terminals of a voltaic battery are put across one
another, the end of the positive wire beyond the contact
becomes red hot: the negative wire remains cool/' From
this it is clear that the electric wave in the condensed air
coating exercises some propulsive force along the positive
wire, and that the propulsion is carried beyond the point
where the wires meet, which can only be at a small spot on
one side of each wire : and the heating of the wire is due to
resistance to the electric force on this part of the wire
beyond the contact: that is to say, that the electromotive
force of the current that has come to this part is expended
in causing chemical combination between the condensed
air and the surface molecules of the wire. This experiment
would also appear to confirm the idea that negative elec-
tricity is a want of electricity, for if there were a negative
force, it should heat the other wire : but this we will consider
further on.
" If the ends of two copper wires be bent into hooks, and
one of them be heated, on placing them in contact, a
current will be produced due to the presence of a thin film
of oxide on the heated wire. With two platinum wires
no such effect is obtained." Platinum is neutral like lead,
and in some lists the one is put above, and in other lists is
put below the other : the want of oxidation of the platinum,
and probably the dense oxide of the lead, make them both
equally inactive. The action on the heated wire resembles
the action at the anode in the voltaic cell: the acid assists
the oxygen to attack the zinc of the cell: the heat assists
the oxygen to attack the copper of the wire: and the current
increases the effect in both cases. Without the chemical
action there would be no electric action.
" If we tie a knot in a piece of copper wire and pull it
tight, and hammer it if need be, and heat the wire to one
side of the knot, a current will be sent through the wire
74 THERMOELECTRICITY
when the ends are joined to form a circuit/' This is some-
times put down to molecular disarrangement caused by the
knot, but it is due merely to the knot having more body
for absorption of heat, and less surface for thermoelectric
action than the same quantity of wire on the other side
of the heating lamp. The effect happens equally well if,
instead of the knot, the wire is left straight but held in a
pair of pliers on one side of the lamp. The pliers take the
heat from the wire and keep the further part cool, and so
prevent the extension of acting surface on that side, thus
giving unequal chemical action in the two directions which
is all that is needed to cause a current in a circuit.
" When tourmaline is being heated, one end is positively
electrified and the other negatively: while cooling the
reverse: and all action ceases if the crystal is heated to
150 C." Tourmaline is a solid which has a peculiar action
on light, being more transparent to light vibrations with
one orientation than to those at right angles* to them, but
we have no authorization for supposing that any but the
surface molecules of solids are acted on by electricity, or
are concerned in producing it. The electricity must be
produced in this case by the chemical interaction of the
surface molecules with the condensed air on the surface,
for when the latter is driven off by the increase of tem-
perature to 150 the action ceases. It would seem as though
the surface molecules, when they are expanding with heat,
send electric waves through the condensed air in one direc-
tion, and when contracting through loss of heat send the
waves in the opposite direction, but what causes this action
is not known. The composition of tourmaline is very
complicated, as it may contain a dozen or more of the
elementary substances, and we can only guess that the
temperatures at which heat causes the substances of the
mineral to react with oxygen are various, and that the
place of the potential unit changes in consequence.
THERMOELECTRICITY 75
Selenium is a substance that has a very strong thermo-
electric action, about forty-five times as strong as iron :
and a very strong resistance to the passage of the current,
about a thousand million times that of iron: and a very
remarkable quickness and amplitude in its conduction
changes when acted on by light. Its resistance to electric
conduction is lessened by light, and the action of the light
is instantaneous. Professor Adams found that the light
from a taper, at six inches distance, reduced the resistance
by about an eighth.
If two copper wires are wound on a plate of nonconducting
material so that they cover the surfaces in an arrangement
parallel, alternate, and close to but not touching one
another ; and melted selenium is poured over one face so as
to fill the interstices between the wires, and is allowed to
cool slowly so that it may crystallize; the arrangement
forms what is called a selenium cell, and if the ends of the
two wires be joined to the terminals of the battery, the
selenium is interposed in the circuit and will conduct the
current, with more or less resistance according to the action
of light falling on it. If a succession of strong lights and
shadows, such as would be caused by sunlight passing
between, and interrupted by, the cogs of a rotating toothed
wheel, be allowed to fall on the prepared face, the current
will produce a tone in a telephone. This sort of arrangement
forms the basis of the telephotographs and photophones
lately invented.
Selenium is a material like sulphur, but darker: light
affects its surface, and the effect increases somewhat for
some time and perhaps passes a little inward, but the first
incidence of the light affects the surface molecules only
and instantly. Selenium has a strong chemical attraction
for oxygen, and the resistance it gives to the current must
be, its perversion of the electromotive force from electro-
lytic action in the condensed air, to the promotion of the
76 THERMOELECTRICITY
chemical union of the selenium with the oxygen. Anything
therefore that assists the selenium to combine gives more of
the electromotive force to the production of the current,
whether this be through the new selenium compound or
through the condensed air. It would appear that in this
case the current passes through the selenium compound,
for though the actinic rays have been found to affect con-
duction in other cases, the change has been but slight in
comparison with this. A particular point to be noticed
is that the molecules must be in their closest relations with
one another : the selenium must be left to crystallize slowly :
the molecules must be naturally arranged and not in a
heterogeneous mixture.
The increased action of galena as compared with lead,
which has no action, is probably due to the sulphur which
has a strong chemical attraction for oxygen and acts like the
selenium, and would show that the force which is indicated
by the letter S is due to this combination of surface mole-
cules w r ith oxygen.
In all the examples that we have been considering, except
that of tourmaline, the voltaic arrangement is plain to seer
the condensed air being the electrolyte, and the metals, or
single metal with two potentials, being the nodes. The
tourmaline experiment is particularly interesting. It
reminds one of the working of the statical machine: the
heat causes the separation of the positive and negative
electricities to the two ends of the crystal, just as in the
machine they are driven into the conductor and the cushions.
Meantime we see that the production of electricity by
heat is due to chemical action and electrolysis. The differ-
ence of chemical action due to difference of heat produces
the electricity and the particular arrangement of the wires
allows the formation of a current.
CONDUCTION
CHAPTER XI
CONDUCTION THROUGH GASES
WHY are some materials conductors and others not ?
" Perfect vacuum is a perfect insulator/' therefore we
may leave the aether out of consideration, and go on to
more substantial mediums.
Let us then inquire into the activity of gases.
Schuster has found that " the discharge through gas is
electrolytic/' and J. J. Thomson says that " chemical
decomposition is essential to gaseous discharge/'
" Ultra-violet light increases the conductivity of air/'
the reason being that its vibrations act to produce a ten-
dency in the gases of air, or what they carry with them,
to chemical change, and the electricity finds the air there-
after more easily acted on.
Flames conduct because they are gases in the act of
chemical change, and heat improves the conductivity of air
because heat acts in much the same way as ultra-violet
light in making the material more ready to change. Smoke
also discharges electricity slowly, but surely and thoroughly,
as it is largely composed of heavy gases and vapours that
are slowly changing, and being sluggish in their change can
only aid the electricity sluggishly. " Radiant heat from
red-hot iron conducts/' partly because the vibrations of
its radiant heat act on the air, and partly because the iron
sends into the air a gaseous emanation of iron and oxygen
that electricity can act upon. " An electroscope is dis-
charged by a flame brought near it," because the flame
and the air about it are filled with active chemical particles :
77
78 CONDUCTION
as Silvanus Thompson says, " Flames and hot air from red-
hot iron are good conductors on account of the chemical
change going on in them/'
Under ordinary circumstances gases are indifferent to
electricity, and are unaffected by it, hence they are good
insulators. If this were not so, telegraphy, as it is now
carried on by wires in the air, would be impossible. There
is, however, always a slight leakage of electricity from the
telegraph vrires through influence, and through convection
by the impurities floating in the air, and this leakage is
falsely attributed to what is called ionization of the mole-
cules of air, while as a fact the air has nothing to do with it,
for air can only be brought into action by the expense of a
much greater amount of electrical force than the wire has
to dispose of such a force as that which acts in the light-
ning flash.
The air always carries with it some water vapour, dust,
microbe germs, and the molecules which many solids and
most liquids are constantly discharging from their surfaces
and which mix with the air in the form of gas or vapour.
Many things can facilitate and hasten this effusion of the
molecules and increase their number in the air, such as
electricity, Rontgen rays, the sun's actinic rays, and heat
rays: and there are other things which can of themselves
load the air with wandering particles, as flames, incandes-
cent metals, radium, corrupting refuse, etc.: and these
floating materials, when chemically combined and aggre-
gated into particles, are capable of accepting small charges
of electricity and then would help, by this convection, to
discharge any electric accumulation, and it is even possible
that if they were numerous enough they might, as it were,
form a bridge that would effect the discharge by electro-
lytic interchange that is, conduction among themselves.
But in none of these cases could the air itself be used in the
convection, and could not be used in conduction, as it can be
CONDUCTION 79
brought into chemical combination only by the action of
great electromotive force.
Mixed or compound gases are poor conductors at any
time, in fact they are classed as insulators, and it is only
when great electromotive force is applied that they can
be made to conduct, and even then, if by some means their
resistance is increased, they will not conduct at all. A
great increase of pressure on air makes it a perfect insulator,
for the simple mechanical reason that the pressure has made
it more difficult for the molecules to be moved.
Pure gases are nonconductors. As an instance, hydrogen,
even when a mere skin on the copper in the voltaic
cell, quickly stops the action by its nonconductiveness,
which is due to its being an element and therefore not
chemically composable with itself. But " those gases
which when heated are decomposed, or molecularly dis-
sociated, so that free atoms are present, are good con-
ductors " because they can recombine chemically.
It is said that " gases (including steam) are perfect non-
conductors, except when so rarefied as to allow of discharge
by convection through them/' But there is no convection
through gases at any time, as the passage of electricity
through them can only occur by electrolytic conduction:
and rarefaction makes this easier by making the molecules
easier to move. We must not, however, accept even this
as a conclusive rule except for compound gases, for no simple
elementary gas molecule can act in conduction. Before it
can conduct it must become a part of a compound gas mole-
cule, and no rarefaction or force of current can make it
conduct when single: and if the current is made so strong
as to force a passage through any compound gas, it
does so with electrochemical conduction and not by
convection.
Those who advocate ionization of gases consider their
theory as proven when they succeed in forcing a current
80 CONDUCTION
through a gas and breaking down its resistance : or rather,
apparently breaking it down, for the discharge takes place
in the usual electrolytic way owing to the great force of the
current detaching vapour molecules from the electrodes,
which mix and combine with the gas. Very little has been
done to clear up this question, but hydrides have been
found in the tubes when hydrogen has been used in these
experiments, and it is extremely unlikely, when further
investigation has been made, that any exception will be
found to the rule that a current is carried electrolytically
in gases.
The amount of electricity passing in these experiments
is so small, on account of the small quantity of additional
vapours discharged into the tube, that an ordinary galvano-
meter is useless to measure it, and either an electrometer
or an electroscope must be employed.
The electrometer consists of a thin slip of aluminium hung
by a quartz fibre and surrounded by quadrants of brass.
It is kept charged with electricity, and shows, by the move-
ments of the slip, any addition of charge, or any increase
or decrease in the force of the charge. In the electroscope
a charge makes the leaf stand out, and the rate at which
it sinks shows how the charge leaks away: and these move-
ments of the leaf are, in delicate cases, observed through
a microscope.
The idea of ionization is, that because a simple gas cannot
conduct electrochemically, and yet has been found to carry
the current in some way after it has been acted on by some
particular ray, that it must do so by convection owing to
some change in the molecules that enables them to take
little charges of electricity from one electrode with which
they dart to the other electrode. This idea has been en-
couraged by the fact that a strong current in a vacuum tube
appears to have some effect in discharging the oxygen of the
rarefied air with some force away from the kathode, but this
CONDUCTION si
is <|uite outside the subject, as the oxygen in that case
carries no charge at all.
After ionizatioii " 1 he conduct ivily of 1 he gases appeared
lo lc entirely <luc lo loose detached chained particles: the
conducting power did not last long, the particles clinging
to tin sides of the vessel: it lasted longer if there was no
dusi present/' Tho loose detached particles certainly
carry a charge, and would, if they reached the other olec-
irode. deliver it there, but very few, if any, do this: they
are convecting not conducting and go to the nearest solid
body and stick there. I )ust, whether it is metallic or other-
wiso, attracts gaseous molecules, and when these gaseous
molecules are thus removed they can no longer combine
with the air or gas in the tube, and the current is stopped.
It is supposed by the believers in ionization -that the
ioni/ing agent converts the indifferent gas molecules into
eager carriers of elect ricity : thai they a. re enveloped in
electricity: and being discharged from one electric terminal
they strike the other and unload: they move, under ordinary
experimental conditions, according to the statements of
even I he most enthusiastic observers, at the very nneleet rieal
rate of less than half an inch in a second, as their fastest.
Tin- cessation of the current leaves many in the field, and
though they must still be charged, and must still retain
their original projecting force, they abandon movement.
Left to themselves they simply disappear. It is variously
explained, that oppositely charged ions combine and
neutralize each other: or that they give up their charges
to neighbouring objects and resume wandering on their
own account: or that the electric force drives them to an
elect. rode to be discharged: but this last cannot be, as then?
is no slow dying away of the conduction when the current is
cut off, but an instant cessation, and before they disappear
they are found scattered throughout the tube and not
eolleeted at the electrodes.
82 CONDUCTION
What truly happens is this. There must always be a
chemical change to accompany the conduction of electricity,
and there can be none in pure simple gases: but with im-
purities forced upon them the action in these gases is in no
way different to the action in the electrolytic cell. The
molecules of the substances that are disseminated through
the gas, and which may be called ions or any other name,
are present in a state of vapour (except those collected in
particles of measurable dust which does not act chemically),
and when actinic rays of any sort are passed through the
mixture, the components are encouraged to combine and
thus form an electrolytic bridge for the electromotive force
to dash across with its light-like swiftness, and the com-
ponents move in two slow streams in opposite directions
towards the electrodes. So it happens that when the
current is cut off the last of it reaches the opposite electrode
instantly, and there is none left for the molecules to get rid
of. The ions disappear after a time, either through chemi-
cal change or by adhering to the glass of the tube : or they
can be quickly washed away or removed in various ways,
simply because they are compound molecules of vapour
mixed with the air, from which they can be cleared away
like any other vapour.
" Professor Thomson has measured the electric charge on
the ions of gas, and finds that it is the same as that carried
by the ions in solution/' This is quite as it should be if we
may change the wording a little and say "has measured
the conducting power of the components of gas, and finds
that it is the same as the conducting power of the com-
ponents in solution." For the ion, or molecule, whether
solid, liquid, or gas, has the same atomic combining value,
and it does the same (amount of chemical change in which-
ever condition it may be.
A dust particle, wherever (it may be, collects upon itself
the condensed molecules of the vapours round it, and in our
CONDUCTION 83
air it condenses on it the floating water vapour, and when
the collection is heavy enough it falls, combined with other
loaded dust particles, as a raindrop, and it is said that no
raindrops are formed without these disagreeable nuclei.
Mr. C. T. R. Wilson has made an apparatus to show that
" ionized air " acts in the same way that the dust in air does.
The following is a description of the apparatus and of what
was done with it. There is a domed bell glass that can be
suddenly exhausted : this is practically all that is necessary
to know about the machine, its pressure gauges and the rest
of it are detail. The bell is filled with ordinary air and
exhausted repeatedly, and the chilled water vapour, collect-
ing on the dust particles, forms a fog which falls^to the stand
of the bell, and by this means all the dust that is in the air
is got rid of: after this, although the condensed water has
again evaporated and mingled with the air in the bell, ex-
haustion can produce no more fog, as there is no more dust
to serve as nuclei to the water-drops. If now Rb'ntgen rays,
or rays from radium, or ultra-violet rays, are directed on the
bell, fog is again formed when it is suddenly exhausted.
This is supposed to prove that the gases have become
ionized that is to say, that their molecules have been
changed to travelling carriers charged with electricity and
to have become the nuclei of the water-drops.
The latter part of this supposition is patent enough.
Something is doing the same work as the dust particles
previously did. And if by ionized is merely meant that
the molecules of the gases have been acted on by the actinic
rays, and have combined to form nitrogenous or other com-
pound molecules on which vapour can condense as it did on
the dust motes, the whole supposition is right: but if it
means that they have become coated or filled with electri-
city, it means the metaphysical introduction of an utterly
unnecessary and impossible complication.
" No one doubts the material nature of the carriers in a
84 CONDUCTION
Crookes' tube from which all the gas has been exhausted
as completely as possible/' These certainly are the only
carriers in the tube, but it is not at all apparent that these
bits of metal are torn away from the electrode by the force
of the current for the express object of being discharged
against the opposite pole each with its load of electricity,
for very few of them get so far, and the electric current does
not use them but is transferred electrolytically by the com-
bination of the invisible molecules of metallic and other
vapours mixed with the residual air: and that this is the
case is shown by the colours of the discharges in these
vacuum tubes, their colours being due to radiation from
gases and metallic vapours and not to any action of solid
particles. Also, when the tubes are exhausted as com-
pletely as possible, the current cannot pass although the
particles remain.
It is, however, very difficult to prevent electric com-
munication, even in the most highly exhausted tubes, when
large electrodes are used, but the effect is not due to con-
duction in the air, but to conduction on the surface of the
glass, and perhaps also to influence waves, the action of
which will be one of our next subjects of study.
There is an experiment devised by Hittorf which is
supposed to show that electromotive force prefers to strike
across a long gap rather than a short one in highly rarefied
gas. " Two glass bulbs are joined at their nearer sides by
a short wide tube ; and two electrodes, which are sealed into
their further sides, reach into this tube and have their
points a twenty-fifth of an inch apart: the bulbs are also
connected by a spirally arranged narrow glass tube twelve
feet long. When the pressure of the air in the apparatus
is reduced to a very low value, the discharge takes place
through the long tube and not across the space between the
points of the electrodes/'
In apparatus of this sort the bulbs and the sealing patches
CONDUCTION 85
and the long tube are made of soda glass : and what happens
when a strong current is applied and its passage is denied
by the highly rarefied air inside, is that it forces a passage
on the outside surface between the insertions of the elec-
trodes, and it finds there comparatively easy conduction.
Even if the machine were made of flint glass there would
be no security against outside conduction, as the surface
might easily be contaminated by dust or handling. The
contained air in this machine had nothing to do with the
action.
John Hopkinson, who was a careful experimenter, was
once taken in, in much the same way. Making experiments
to show that electrolytic conduction passed through glass,
he put a test tube containing an electrolyte in a jar contain-
ing another electrolyte and completed the circuit with a
loop of wire : there was a slight current that was much in-
creased by boiling the liquid in the jar. But he found,
or rather Lord Kelvin showed him, that the current did
not pass through the glass, but over its surface. This
shows how careful we should be in interpreting experi-
ments.
" Workers are justified in using hypotheses for extending
inquiry, but they need not be taken as facts/' and very
often " opinions are not specifications of fact but of fancies,
and the more sensational they are, the better they please
the mob and the more the exponent is applauded/' It is
most likely that the wonder -inspiring ideas of the day will
by another generation be detected as absurd and futile, and
their places filled by facts of pure simplicity.
It almost seems as if it were for such sensational reasons
that the impossible electrical pack -carry ing ion, which is so
charmingly active and incomprehensible, is so constantly
reincarnated: but certainly it is by no means generally
accepted by men of science, as the following extracts from
the address of Professor H. E. Armstrong, the president of
86 CONDUCTION
the chemical section of the British Association at Winnipeg,
will show.
" The ionic dissociation hypothesis is a beautiful mare's
nest which fails apparently to fit the facts whenever it is
examined/' and " the dissociation hypothesis is incom-
patible with facts/' We shall therefore be in good com-
pany if we reject the ionization theory and pin our faith on
believing what all the facts point to that " every case of
electrical change is accompanied by chemical change."
CONDUCTION
CHAPTER XII
CONDUCTION BY LIQUIDS AND SOLIDS
WE have already studied the manner of the passage of the
current through the fluid in the voltaic cell, and through
fluids in separate vessels in the circuit, and have found that
its action is always the same when it passes through liquid,
it can only do so by electrolysis : it decomposes and recom-
poses the molecules of the liquid.
Electricity seems to have a partiality for fluid as a con-
ductor. We bury our earth wires where it is hoped the soil
may remain damp : so also the ground ends of our lightning
conductors. In the lightning stroke the current passes
through the body in preference to going over the dry skin,
and it does this because the blood and other fluids of the flesh
are suited to its need for chemical change. The proneness
to putrefaction of animal bodies after the stroke shows the
electrolytic manner in which the current has been enabled
to traverse the body: there is a small burnt mark at the
point of entry and another at the exit, where interference
has produced heat, but in the body there is no burning but
only signs of chemical change.
In some cases where men have been in the rain sufficiently
long to get well wetted before gaining shelter, and who have
after this wetting been struck with lightning, the clothes
have been torn off and there have been marks on the skin,
and this has happened because the current found its pref-
erable way through the wet clothes and over the warm wet
skin.
A pine tree when struck with lightning is very much
87
88 CONDUCTION
damaged, and its bark is stripped off it. Its branches
stand out square from the trunk and convey no rain to it,
and the bark is rough and keeps any water that may be
driven on to it in unconnected patches, and its resinous sap
is a bad conductor: so it is ruined: while the beech with its
more upright branches, which drain the rain on to its smooth
bark that is soon wetted all over, sustains no damage
because the water on the bark gives a fair channel for the
discharge.
It has been considered that the wet clothes and the fir-tree
bark are driven off by the formation of steam, but this is a
very doubtful explanation, and we can perform an experi-
ment that will prove to us that the force that does these
things can cause action in this way without the production
of any steam. " When a current is sent through a closed
glass tube entirely filled with water, the glass is shattered."
Because, you might say, as these others have done, that
the electricity has changed the water to steam; or because,
as some physicist might say, you have forced in a quantity
of material electrons. But .neither has been done. The
resistance to the electricity does give a small amount of heat
to the water, but it is so little that a thermometer is not
delicate enough to distinguish it, and certainly the glass
would have withstood a small pressure of steam. What
exploded the tube was, that the electromotive force decom-
posed the water into separate liquid molecules of hydrogen
and oxygen, and so for a brief instant allowed of their ex-
pansion in bulk to fifty per cent, more than their bulk when
combined as water. They recombined almost in the same
instant, but the mischief was done and the glass shattered
by the first part of the electrolytic action of the current in
passing through the water.
Water is not a very good conductor : a single DanielFs cell
has not enough electromotive force to overcome the cohesion
of the components of the water molecules, still two cells, or
CONDUCTION 89
any sufficiently strong current of any sort can always make it
act, and it acts thus whether it is in the form of vapour or of
fluid : but ice is a nonconductor, because, as one may easily
guess, the resistance to change in the water is enormously
increased by its solidification.
" Threads of silk are nonconductors, but wetted with
salt water they conduct well " : but it is the electrolyzed
water that conducts and not the unchangeable silk.
The best fluid conductors are the solutions of the metallic
salts, not because of any attraction of their metallic mole-
cules for electricity, but because the liquid components of
these salts are easily separated chemically, and for that
reason are easily electrolyzed.
There are some liquids that are nonconductors, such as
oils and liquid resins: their molecules are compounded of
many elemental ones, so their nonconduction is not due to
elemental singleness, nor is it because they are not decom-
posable, for a little heat can do this: but it is because the
electric wave is either not strong enough for the work, or
else lacks that particular vibration that can act on them
and that the heat wave possesses.
Elemental fluids are nonconductors, except oxygen,
which is changed into ozone by the current. Hydrogen,
which is perhaps unchangeable, does not accept electricity
whether it is fluid or gas.
It has now apparently been generally accepted that the
conduction of electricity through fluid is effected by the
method of electrolysis, but the idea was bitterly opposed at
first by those who argued in favour of travelling ions with
their packs of electricity and lightning speed of travel, and
there are still some who are loth to discard so simple an
explanation, and have modified the old ion idea, saying that
the electricity forms part of the molecule which it leaves
to dart through the fluid. Such a theory gives no explana-
tion of the separation of acid and basic molecules at the
90 CONDUCTION
electrodes: and the motion that this ionic darting would
produce in the fluid would be most tempestuous, far more
violent than the most furious boiling, so, contemplating our
apparently unmoved electrolytes, we may reject any such
theories as false.
Those fluids only that are decomposable by the electro-
motive force are conductors. The electromotive force
reproduces in its course through the fluid the same movement
that produced itself. It impels the acid component mole-
cule to move in one direction, and the next basic molecule
takes it up and combines with it, and in this way, step by
step, each wave is transmitted with great speed through the
fluid conductor without the least appreciable movement of
the fluid, for the movement in the material caused by each
wave is only the inappreciable distance of one molecule's
breadth.
The conduction of solids depends on several conditions,,
and among, these their material counts most. Metals, in-
cluding carbon, are the best; copper conducts about a
million times better than the average electrolyte. Stones
are generally bad conductors, but soap-stone is good com-
pared with other stones.
Among metals proper, silver heads the list as a conductor,
and on this account used to be taken as the standard of
comparison for conduction with a nominal power of 100.
Compared with it copper has a conduction of 94, iron 16,
mercury 1-5, carbon one three-thousandth. The other
solid elements are indifferent conductors, selenium, for in-
stance, having only a forty thousand-millionth part of the
conductivity of silver. Alloys are worse conductors than
either of the metals composing them.
The conduction of metals does not appear to depend on
their atomic weights, for silver being 100, aluminium is
CONDUCTION 91
registered at 55, and lead is only 7. Nor does it seem to be
due to their oxidizability, for iron is only 16 against plati-
num 13. It is probable, however, that both these the
weight and the oxidability have something to do with
their conducting powers, but that more than either, the
molecular condition of the surface tells. Silver is of all
metals the most smooth of surface, while if one goes down
the list, copper, gold, aluminium, platinum, iron, lead
each shows a decrease in smoothness, though mercury, which
comes after lead, seems to give a contradiction to this idea.
Evans found that the carbon filament in an incandescent
lamp gave a better light when bright polished than when
dull, and that the temperature to which a dull filament has
to be raised to give a definite light is higher than that of
a bright one, therefore this lesser resistance of the bright
filament we may put down to its smoothness. Also, ex-
perimenting with two platinum wires in vacuum tubes, one
bright and the other smoked, he found the resistance of the
smoked wire nearly double that of the bright one, at a dull
red heat: and the tube of the " bright wire was not un-
pleasantly warm to the hand, while that containing the
other was hot enough to blister the skin/' The waves of
electricity passing over the wire, in one case produced light
and in the other heat. The resultant of motion was the
same in both cases, but in one there was more light motion
produced and in the other more heat motion. In what
possible manner could corpuscular electrical ions produce
these different effects ?
Taking smoothness as the reason for conductivity, one
could understand the falling off in this respect of the alloys,
which with mixtures of molecules of different shapes for
surfaces could not be expected to have great smoothness.
Lead, tin, zinc, and cadmium, which are somewhat alike,
have a conductivity in their alloys more or less correspond-
ing to what may be calculated from the percentage of the
92 CONDUCTION
metals in their composition, but all other metals, either
alloyed together or with these, show a much lower conductive
power. Silver 98 parts alloyed with tin 2 parts has a conduc-
tance of 23 instead of 98-2, as it should have by calcula-
tion : and silver 10 parts with tin 90 has 11-5 instead of 20-1.
But there is this also to be said, that besides wanting in
smoothness, the metals in alloys may react on one another
and produce currents which would be equivalent to the
polarization in the voltaic cell, and the greater the potential
difference between the metals mixed together, the greater
the resistance, and this difference we see above where silver
and tin, which occupy places the one at the top and the other
near the foot of the scale, show a great falling off in con-
duction in their alloys, while alloys of the other metals
which are near each other in conducting power have better
preserved it in the mixture. " A very slight impurity in
copper wire increases its resistance/' A very small quan-
tity of impurity could have very little effect on the evenness
of the surface, but would have some amount of action on an
active electrolytic metal like copper. Still this does not ex-
plain the great falling off in power of alloys of the noble metals,
and in them probably it is the surface change that tells.
On account of their power of conduction and their
ductility, metals are the only substances used for con-
ductors of electrical machines. Iron rusts, and other metals
are too expensive or otherwise unsuitable, so copper is used
almost exclusively, and on this account has lately been
taken as the standard for comparison at 100 : the numeration
for silver and the others being proportionately increased.
Iron being very cheap is used for land telegraphs, as the
distances are not so long as to make its resistance an objec-
tion, but for deep sea cables it cannot be used, as any possible
electromotive force applied would be worn out before the
terminus was reached : so the more expensive copper which
conducts six times as well is used.
CONDUCTION 93
Among non-metallic solid conductors hemp thread is about
the best, while silk thread is a useful nonconductor. The
nonconductors are not however entirely nonconducting,
but have so little power of conduction that it is very difficult
to measure it less than a billionth of that of silver, and
the more so because it is next to impossible to get rid of
the interference of vapour and other matters in the air and
clinging to the articles used. Water vapour conducts as well
as water, and though its power is less than a millionth of
that of silver, still it is, on account of such power as it has,
one of the most obtrusive substances in electrical experi-
ments, discharging machines in damp weather almost as
fast as they are charged.
All solids, unless they are permeated with fluid, conduct
on their surfaces only : so also do mercury and molten metals,
but this is because these latter are elements and chemically
unchangeable in themselves.
Bjerknes, when experimenting with resonators of different
metals, plated (by electrolysis) an iron resonator with copper
and a copper resonator with iron, and found that their
actions were those of their skins and not of the contained
metals. The surfaces only were used for conduction, and
this points also to the condition of the surfaces as the cause
of the difference in conduction.
Heat changes many solid nonconductors of compound
material to conductors, and when they melt, or when any
chemical change is brought about in them through the
action of heat, they may become electrolytes to the current,
and often good conductors. With metals, however, it is
quite the contrary: they lose their power of conduction
nearly always when melted, and if in a few cases some small
power is left, it is still by their surfaces only that they con-
duct : for no chemical change can be made in their elemental
substances by electricity , and without this there is no electro-
lytic conduction.
CONDUCTION
CHAPTER XIII
ELECTROLYTIC SURFACE CONDUCTION
ONE might suppose from what we learnt in the last chapter
that we had exhausted the subject of conduction by solids,
but the fact is that our examination so far has been merely
introductory : we have still much to learn.
The first theory about the conduction of electricity by
solid conductors was, naturally enough, that it used them
as a sort of pipes. But it was very soon discovered that
hollow bodies have no electricity inside them whether they
are conducting or not, and that the thinnest metal tube
conducts almost quite as well as a bar of the same diameter
does. So till very lately the surface has been considered
as the place of electric transmission, though there have been
individuals who, harking back to old fancies, have made
measurements of the depth to which the electricity soaks
inward. But latterly a theory has been brought forward
that the electric current is transmitted through the medium
surrounding the wires, and does not use the wire in any way
except as a sort of clue to give it direction.
It is a pity that statements should not be made with as
great clearness as possible, instead of being given to us
disguised in words which may have several meanings.
There is nothing definite about the word medium. If in this
case it means the aether, then the idea is wrong, for a vacuum
which contains aether and nothing else is an absolute non-
conductor : and a wire heated red hot and cooled in hydrogen
is a nonconductor, though there is plenty of aether with the
hydrogen. It is idle to suppose that the air is meant as the
94
CONDUCTION 95
medium, for if the current acted on the air the electricity
would be dissipated at once: and the same objection applies
to anything conceivable mixed with the air. And it does
not appear possible to explain on these terms conduction
through a surrounding medium. How is it that the wire,
if too thin, becomes heated, and may be entirely burnt away ?
Or why is one sort of wire a better clue than another ? So
we will not pursue this new theory, but study the arguments
for and against surface conduction.
The fact that copper wires used for carrying electric
currents are made brittle is quoted as a proof that the
current passes through the body of the wire. But the mere
heating and cooling of this wire will make it brittle without
any help from electricity. It may be that absolutely pure
copper would not be affected either by temperature or by
electricity, and that the effect shown is due to the heat
caused by the current aiding the impurities to separate from
the copper: a very little impurity greatly increases the re-
sistance in copper wire. Brass wire, if kept for any time,
whether used or unused, becomes brittle and useless. In
some experiments which were made to observe the effect of
heat on cast iron, although the heat was not pressed above
a dull red, it was found that the carbon inclined to aggregate,
and it is quite comprehensible that if a body is made up of
a mixture of two or more sets of crystalline molecules of
different shapes and unlike facets, that when expansions
and contractions occur in the mixed mass, the adhesion of
the unlikes would be shaken if one of the material molecules
should expand or contract more or sooner than the other,
and that the likes should collect together with a bad effect
on the solidity of the mass. There is an alloy which is called
invar, from its remaining unexpanded by heat ; in it we must
suppose that there is a constant struggle going on between
the different sets of molecules, and it is to be anticipated
that it will fail through this. However this may be, it
96 CONDUCTION
would seem that the brittleness of the copper wire is not
necessarily a consequence of its use as a conductor, but
rather is due to its want of purity.
" Heat increases the resistance of pure metals/' Take a
piece of thin wire of pure silver for the conductor between
the zinc and copper of a cell, and roll the middle of it into
a spiral just big enough for a round iron bar a poker, for
instance to go through easily : heat the end of the poker
red hot and pass it into the spiral while the cell is working,
or heat the spiral with a spirit lamp: the current is stopped.
Remove the bar or lamp and the spiral cools very quickly,
but not for some time after the wire has become cold is
the current re-established. The wire lost something because
of the heating, and it does not seem as if the surrounding
medium had anything to do with this : for allowing that heat
could drive the medium away, there could be nothing to
prevent its acting again immediately the wire is cold.
Solids conduct on their surfaces only. Take a rod of
common soda glass and twist the positive and negative wires
of a battery round its ends so that it forms part of the
circuit : it acts as a conductor, though not well ; wetted with
water it conducts better. Now dry it and pass a spirit
lamp flame several times along it, and though it is not hot,
it is a nonconductor and remains so for hours. It will not
do to use any sort of flame for passing over the rod, it must
be a clean flame, for soot is a conductor and is difficult to
wash off.
Try the same experiment with a flint glass rod. At no
time is it a conductor, not even when wetted with water.
Examine the wet surface with a magnifying glass and you
will see that the water has collected in separate little
patches they have no continuance. But none of this
could interfere with the conduction in a surrounding
medium. There was something on the common glass that
conducted, and a skin of water made it conduct better:
CONDUCTION 97
and whatever was on the surface was driven away by heat,
and afterwards the glass would not conduct, though its
substance was in no way changed. Then again the water
on the soda glass had a continuous surface and conducted
well, and on the flint glass, having no continuity, did not
conduct at all. And the medium round the rods had no
influence or connection with the conduction.
It is a pity to spoil a good flint glass rod, but you can try
the following experiment if you will not accept it without
personal experience. Make the surface rough in some way ;
scrub it with emery cloth and you will see plainly that it is
rough : or soak it in strong solution of washing soda and you
\vill not know that the surface is changed till you come to
use it. Whichever you have done, rub* the rod with fur
and you will find that it gives negative electricity instead
of positive. Wash it, dry it, and clear off the electricity
with the flame of a spirit lamp, and try it in an electric
circuit: it is a nonconductor. Wait for a few hours and
try again: now it conducts, poorly certainly, a good deal
worse than water, but just as well as the soda glass rod,
and when wetted it conducts better, and the magnifier
shows us that the water is not in separate patches, but
forms a continuous skin. Dry it again, and pass the flame
along it and its conductivity is gone. This glass has not
been changed in any way except as to its surface, and the
surrounding medium has not been interfered with: so we
may say that the inner substance of the glass has certainly
had nothing to do with the carrying of the current: nor
surely had the body of the silver wire: nor the body of the
other glass rod: nor the air or other medium round any of
them.
When this spoilt flint glass rod was recovered from its
loss caused by the flame, it picked up something on its
surface similar to that which the other rod had : most likely
the same that the silver wire had. What could they all
7
98 CONDUCTION
pick up under the same conditions but the same thing ?
Something that they got from the air, for nothing else
touched them. Something that formed a continuous skin
on their surfaces and which alone carried the current.
For without it, neither the surrounding medium, nor the
surface of the conductor, nor the material body of the con-
ductor, had any power to conduct the electric current.
If a conducting wire is cleaned, heated, and allowed to
cool in hydrogen or carbonic acid gas, it remains a non-
conductor. Messrs. Bone and Wheeler, by experiments
described in one of the transactions of the Royal Society,
lately published, have shown very clearly that hydrogen
is plentifully condensed on the surface of metals immersed
in the gas, and such is also the case with other gases : so it
is not because it has not received a coating of condensed gas
that the wire refuses to conduct, but, either because none
of these gases can combine with the metal surface to form
an electrolytic conductor: or because (the metal having
no action) the gases are themselves nonconductors, which
is truly the case.
" When a wire is allowed to cool in pure dry air, the wire
becomes a conductor/' Thus eliminating moisture, which
we know is a conductor, we are obliged to come to the con-
clusion that condensed air, either of itself or by combination
with the effluves from the metal or other surfaces, is the
conducting agent on the wire or other surfaces.
Selenium is a very poor conductor, but light falling on it
makes great changes in its powers in proportion to the
changes of the light. The change is instant and has been
used to give a varying cifrrent in telegraphy .that reproduces
pictures, such as photographs, at the receiving station:
they are not, to be sure, such as one would use to decorate
one's room with, or to remind one of beloved ones, but
recognizable and worth keeping as curiosities. Now this
change of current could not come to pass if it was the sur-
CONDUCTION 99
rounding medium that was acted on, for the change is
plainly due to the material or what it has on its surface,
and the medium, whatever it may be supposed to be, is
present whatever substance may be used, but no such action
occurs with any other material so far as we know : and again,
light does not penetrate below T the surface of opaque
material: so here we are again brought back to our old
landing-place, the surface of the conductor, and here we have
it plainly indicated that the surface material and the air
condensed on the surface are both accessory to the action
on selenium. But are they both necessary in other cases ?
That is now the question.
We should say that both are not necessary so long as the
air skin is sufficient for the work. " When a conducting
wire of an alloy is placed between the poles of an electrolyte,
none of the constituents of the wire are found at either pole."
This happens because the wire is not the conductor, nor ever
could be so long as there is an electrolyte surrounding it,
for this is not only more easily acted on than the metal
surface, but is ample to carry the current. And so it would
be if a wire of sufficiently ample surface were used as a con-
ductor in air : the wire would not be the conductor, nor be
acted on by the electricity, but only the ample skin of air
that the wire carried. When, however, the wire is thin and
not sufficiently ample in surface, we see it heated and con-
sumed, because its surface is then called into action, and
it is acted on both chemically and by the heat due to the
chemical action induced by the current.
The conductance of selenium is very small : -00,000,000,025
compared with silver's 100. Silver has no appreciable in-
teraction with pure air and gives little resistance : iron has
some interaction, lead more, and selenium apparently a
great deal : and in proportion to their interactions so do the
resistances seemingly increase. So evidently if a free path
is wanted for the current it is best to avoid any interaction
100 CONDUCTION
between the metal and the air : that is to say that oxidation
of the conductor is a disadvantage because it gives the
electricity more work to do, and that it is more to the
current's advantage to leave the work of conduction to the
condensed air only.
We see, then, that what concerns conduction on solid
material is its surface and its oxidizability. Smoothness
of surface is an advantage : there is nothing to prevent the
continuity of the liquid air covering, or obstructing the
propagation of the wave. Oxidizability is a disadvantage :
it sets up local action and causes resistance and waste of
power.. Cold reduces resistance: it binds the molecules
more strongly together and so makes them more secure from
oxidation or any other separating force, and it probably
increases the quantity of the condensed air on the surface.
The less the air skin is interfered with the better the con-
duction: and when the condensed air is ample for the pur-
pose it is through it alone that the transmission is made.
Skins of other simple gases will not act : a simple gas like
hydrogen condenses fast enough, but it refuses to transmit
because it cannot change chemically. What, then, is the
action of the air skin ? The condensed hydrogen refuses to
transmit because it cannot combine with itself: the con-
densed air is a fluid made up 'of a mixture of oxygen and
nitrogen, of which the first can combine with itself, and
the two can combine together. Can anyone doubt that
the action is electrolytic ? It is by the combination of the
oxygen with itself as ozone, and by its combination with
nitrogen, that the current finds its road, and if you want
confirmation of this, you will find it whenever the spark
forces its way through air, when you will find that these
substances are produced in such quantity as to be strongly
perceptible to smell. The liquid particles of air on the
conductor are acted on by the electromotive force in the
same manner as the liquid in the voltaic cell is acted on:
CONDUCTION \ \ f-'OR^ ; J<'1
they are dissociated and combined by every wave of the
force, and so transmit the current.
Electrolysis is in this, as in all other cases that we have
examined,, the road of electricity. Without chemical com-
bination we have found no conduction: without fluid there
has been none : fluid, or its vapour, appears to be the electric
medium, and chemical action in the fluid or vapour its
means of transmission. There is no conduction of electricity
in solid substances whether metallic or otherwise.
;x M :-*': **;: 5 : / '
*:,,*/
"CONDUCTION
CHAPTER XIV
NONCONDUCTORS
WE have settled our ideas about conductors , but have hardly
mentioned nonconductors, and so far as we can gather from
books on electricity and what we have ourselves seen, there
seems to be little to be said about them : at any rate little
has been said, and they seem to have excited scarce any
interest. Still they form a part of our subject, and we ought
to know what we can concerning them and their want of
conduction, and we may perhaps stumble on something
worth knowing in v the search.
The following is a list of nonconductors taken from
Professor Silvanus Thompson's well-known book. Vitreous,
such as glass and slags. Stony, as slate, marble, stoneware,
steatite, porcelain, mica, asbestos. Resinous, as shellac,
resin, beeswax, pitch, gums, bitumen, ozokerit. Elastic,
as india-rubber, gutta-percha, ebonite. Oily, as oils, fats,
paraffin, paraffin oil. Cellulose, as dry wood, paper, fibre,
cellulose.
"It is the nonconductors on which electricity does not
spread that can be charged with electricity/' Quite so,
but why does it not spread ?
The first thing that strikes one is that the substances
named in the above list are all compound bodies: bodies
in which the surfaces are made up of particles of different
shapes and powers of cohesive attraction: surfaces on
which one set of molecules of superior attraction might
draw to themselves all the condensed air or deposited
vapour, leaving the other molecules wanting, and so
102
CONDUCTION 103
producing a discontinuity of conducting surface. " Flint-
glass when polished is not hygroscopic, and is a very perfect
insulator: with the surface roughened its insulating power
is lost. Common glass is slightly hygroscopic, and not
nearly so good an insulator/' This is probably a hasty
explanation, made to explain a fact which was of small
interest to the writer of the extract, and made without
sufficient examination.
Bacon says, "Argumentum non sufficit sed experientia,"
and Messrs. Bone and Wheeler by some experiments re-
garding the combination of hydrogen and oxygen condensed
on metal and other surfaces, the details of which were
published in the transactions of the Royal Society, have
given us some " experientise " which are instructive on
certain points connected with our subject.
They say, that " whatever may be the mechanism of
the surface action, the gas actually lying in the surface is
in a different condition from the main body of the gas,
and that this condition is more favourable to chemical
interchanges. A spiral of platinum will ignite electrolytic
gas (hydrogen and oxygen) at 90 F. It is made more
active by having its air skin removed before introduction
to the gases. Finely divided silver will combine the gases
at 270 F., and gold at 470. Other substances, as charcoal,
pumice stone, porcelain, rock crystal, and glass, require
temperatures approaching 630." It is plain that cohesion
is the active power in these cases . The solid wire has more
attraction of cohesion than the silver grains, these more
than the filmy gold, and the gold more than the other
substances on account of their inferior density. Surface
probably only acts according to the quantity of cohesive
attracting power of the substance it covers, and not accord-
ing to its own extent, otherwise charcoal and pumice would
surety be the most active.
The dense platinum puts so much pressure by its cohesive
104 CONDUCTION
force on the condensed hydrogen and oxygen, that with the
assistance of a heat such as we sometimes have on a summer's
day, it compels them to unite : while the light-bodied char-
coal has to be assisted by almost a red-hot temperature.
This draws our attention to another particularity of the
nonconductors, and that is that they are none of them
very heavy substances, all except the stony and vitreous
being lighter than water. Consequently they attract a
smaller quantity of air to condense on their surfaces than
the heavier metals do, and should therefore be on this
account inferior conductors.
" Platinum foil, rendered active by any of Faraday's
methods, will absorb oxygen but not hydrogen/' There
is no difference of surface to account for this, but what does
account for it is the difference in atomic weights of the
materials, and as a consequence, in their combined powers
of cohesion. From its greater density, the oxygen has
sixteen times the cohesive attraction for the platinum that
the hydrogen has: the combination of the attractions of
oxygen and platinum is sufficient to condense the oxygen
to liquid, but the combined attractions of hydrogen and
platinum cannot reduce the hydrogen : and except as liquid
the gases cannot become attached to any surface. So we
may conclude that want of cohesive force tends to produce
nonconduction by lessening the amount of condensed air
on the surf aces.
All metals probably all substances constantly dis-
charge their surface molecules as vapour, and this effusion
is increased by heat and electricity. It may appear strange
that the metals are not observed to diminish on this account ;
but they of all substances have the greatest density and
therefore the greatest cohesion, and this would restrain their
effusion, and molecules are very small things, and even
radium, which owing to its composition is very active in
this respect, lasts, so the scientists say, for several hundred
CONDUCTION 105
years, although to start with it may be a piece 110 bigger
than a mustard seed. The effluve of silver is greatly in-
creased by heat: also its combination with gases. Hy-
drogen is absorbed at a red heat, 650 F., by solid silver,
and a hydride of silver is formed, and it may be that the
increase in effluve action is due to this chemical com-
pound becoming volatilized. This would explain the pas-
sage of the spark in tubes containing hydrogen, the gas
combining with the metal of the electrode would enable
the conduction to be electrolytic in this case as in all others.
In all of Geissler's tubes the colouring of the light given off
depends on the gases, and on the metals used for electrodes,
which shows that in these tubes the contents do not remain
pure gas, but have become a chemical compound in which
electrolytic conduction can act. It also shows that the
effluves of the metals have become gas.
Now the combination of the hydrogen and metal is a
combination of but two elements, and their electrolytic
movement of conduction has been forced on them by the
current. But an ordinary current cannot make the oils
conduct: and from this we might argue, that the oil mole
cule is preserved from the dissociating action of the electro-
motive force because it is composed of a great number of
various molecules, the combined cohesive power of which
is too strong for the force to break down; and that the
reason why the oils are nonconductors has nothing to do
with their surfaces, but only with their inactivity as electro-
lytes.
To return to the glass rods. There seems to be no reason
for supposing that the condensation of air on the glass rods
(temperature being left out of consideration) is due to any-
thing but the cohesive attraction between the glass and the
molecules of air : or that one glass condenses more than the
other : or that the roughening of the glass makes any differ-
ence in this respect. So we may safely work on the
106 CONDUCTION
supposition that the rods condense equal quantities on their
surfaces, or if there is any difference at all, that it is in
favour of the heavier glass, which is the flint, and which is the
much surer nonconductor of the two. The only cause of
difference in their actions seems to be, as we noticed before,
that there is a different treatment of the condensed fluid
by the different surfaces.
When we examined the wetted flint glass with a magnifier,
we saw the little separate blobs of water scattered over the
surface : and we expect that this glass acts in the same way
with the particles of air or other vapours condensed on its
surface. Flint glass is a mixture, not a compound, of the
silicates of lead and potassium: the atomic weight of lead
is 206-9, and of potassium 39-15, which means that the lead
ingredient would have five and a quarter times more co-
hesive attractive power than the potassium ingredient.
Soda glass is a mixture principally of silicates of sodium,
calcium, and iron, of which the atomic weights are 23-05,
40-1, and 55-9 : so that the difference of the attractive powers
of the most differing ingredients is only about two and a
half, and there is an intermediate attraction to act both
ways and so help to an even distribution and a somewhat
continuous air skin, and this is that which no doubt gives
the soda glass its slight power of conduction.
We have been taught two things by that little instrument
used in wireless telegraphy the coherer one is that a very
small interval will destro3 r conduction, and the other is,
that the air skin condensed on the surfaces of metals must
itself possess a skin. When the coherer is tapped, we can
see no difference in the contents of the tube: it is just an
inch of glass tube filled with filings: but since the tap the
current has ceased to pass, though we could declare that the
filings touch each other just as closely as they did before.
It is the invisible and ultra-tenuous skins of their air cover-
ings that touch, and, remaining unbroken, prevent the air
CONDUCTION 107
coverings from mingling and making a continuous conductor.
When the commotion of an induction wave shivers these
skins, the condensed air coverings join and the current is then
conducted through the continuous condensed air conductor.
The filings have nothing to do with the conduction beyond
attracting a covering of the gases of air which is condensed
and spread with its skin over each piece. It is this con-
densed air only that conducts, and being on metal, it is
probably a thick coating because of the great cohesive
attraction of the metal. If, then, a little tap can separate
these coatings and isolate them, does it not seem as though
the thinner coating on the flint glass might very easily be
broken up and drawn away from the less attractive particles
to form drops, each enclosed in its insulating skin and
attached to the denser particles ?
If we examine what is known about other fluid, in this
connection, we may be able to form some idea as to the
formation of the skin, and we will take water as our sample
liquid, because in fact it is practically the only liquid that
has been experimented with, and because several very
charming experiments have proved beyond any doubt that
it possesses a comparatively tough skin, about the forma-
tion of which however, curiously enough, no one seems to
have made any attempt to theorize. This lack of energy
was probably due to the theory, held a short time ago, of
the condition of matter as being composed of molecules
that were isolated quivering points, an impossible con-
ception that would choke off the boldest investigator:
but this idea has died out, and we may assume, what must
really be the truth, that the molecules of all liquids are
minute globes in close contact. In the interior of the liquid
every molecule, by cohesion, attracts and is attracted by
every molecule touching it: but at the surface, where the
water is in contact with the air, the water molecule must
find that practically all its cohesive attraction is towards
108 CONDUCTION
the water below and alongside of it, because the air mole-
cule, which is seven hundred times its size, has only a four-
hundredth as much cohesive attraction towards it as the
water molecules each have to each other, and we may con-
ceive that the surface molecule is flattened out by this force
into a hexagonal scale, and that these scales form the surface
skin. Now, if this is fact and it is surely reasonable
enough the condensed air forms its skin in the same way :
and when the air condenses on metal surfaces, the strong
cohesive attraction of the metal draws down all the liquid
air molecules equally towards it, so that there is an even
deposit and no gaps in the skin: but on a surface made up
of particles some of which have more than five times the
attraction of the others, the air would first condense on the
more attractive particles and there form a drop with its skin,
and afterwards, though the drop could increase by taking
in more condensed air molecules, it could not join with its
neighbours, and there would be no continuity in the coating,
and it would be a nonconductor.
There is, however, no way of proving this, but we can
surely agree that it was because of a partly continuous skin
on the soda glass, and a skin in separate beads on the flint
glass, that the one conducted and the other did not : and that
this is the difference between any conductor and any non-
conductor, that the one has a continuous skin of air con-
densed on its surface, and the other a similar quantity,
perhaps, but broken into discontinuous patches.
The popular conception of the conduction of electricity is,
that the electric fluid pours through the conductor in the
same way as water is discharged in a gutter or a pipe ; but
examination shows that nothing of the sort occurs, and that
we must come to these conclusions: that conduction on
conductors is due to the electrochemical action, called
electrolysis, of their air skins, and that any action of the
metal is not only unnecessary but detrimental; that the
CONDUCTION 109
difference between solid conductors and nonconductors
is the continuity of the air skin on the one and its dis-
continuity on the other; and that fluids or vapours alone
conduct, and conduct by electrolysis alone.
Conduction is not a rush of material, corpuscular, elec-
tronic, or other, through a conductor, but an instantaneous
transfer of vibrations over possibly great distances, with
molecular electrolytic interchange through infinitely small
spaces in response to each vibration.
RESISTANCE
CHAPTER XV
ELECTRICAL RESISTANCE IS THE OPPOSITION BY CON-
DUCTORS TO THE ELECTRIC CURRENT
" WHEN a current does work it is at the expense of the
current/'
Since the current, wherever it passes, is carried electro -
lytically, it must do this electrochemical work whether it is
in a cell, or on a machine, or on the wires beyond them, but
in commercial installations the work lost in the generator
is small and no separate count is kept of it, and resistance
means to the electrical engineer the resistance on the con-
ducting wires outside the generating-house, and however
good the conducting power of the wires may be, there is,
even in the best of solid metallic conductors, a good deal of
action of the material of the conductor beside the necessary
electrolytic work in its air skin, and to overcome this inter-
ference of the material the current must do work and lose
force which, with a perfect conductor and no interference,
would have carried the current much further. What we
have to examine is the resistance made up of all the work
done by the current.
The stronger the electromotive force, the further the
current will go : the greater the resistance, the sooner will
the force fail to act. We must remember that the strength
of the electric wave does not depend on its quantity, but
on the vigour with which its impulses were originated: a
great wave of electricity without vigour would not travel
any way near so far as a smaller, violently produced wave.
" Doubling the length or halving the cross sectional area,
. no
RESISTANCE 111
doubles the resistance and halves the current." This is
true both of the resistance in a cell and on a conducting wire,
and because the doubling of the cross section of the wire does
not double the surface area of the wire, while it doubles
the possible current, it is brought forward as an argument
to prove that the current must pass through the substance
of the wire, which as they say is the only thing doubled.
But it is not so. There is certainly twice as much metal
in the same length of wire by doubling its sectional area,
but this doubling of the material brings the material into a
relatively nearer position to the axis of the wire, than the
material of the smaller wire, and it is therefore able, on
account of its better position added to its double quantity,
to exert fully twice the cohesive attraction of the smaller
wire, and to collect on its surface fully twice the amount of
condensed air, and to convey by this means fully twice the
amount of current. So instead of being an argument in
favour of the idea that the material of the wire conducts,
it is a proof of skin conduction on solid conductors.
If a conductor has not sufficient surface or is too long, its
resistance is increased and only a feeble current passes. A
part of the current that might have been generated in the
cell, or the machine, and sent over an ample conductor,
is not developed, and a part of that sent is changed to heat :
and " the greater the resistance the greater the heat/' and
the waste consequent to it. To increase the electromotive
force without increasing the capacity of the conductor
will certainly cause some increase of current delivered,
but at the same time it will waste a much increased quantity
of current in producing heat.
If a current is sent on a wire which is so long that its re-
sistance prevents more than a half of it from passing, there
will be some heat in the wire : but if the wire is halved, al-
though the resistance is also halved, the heat will be much
greater, " because the current runs so much the stronger,
112 RESISTANCE
and the heating of a conductor is quadrupled by doubling
the strength of the current/' The heat is not measured by
current multiplied by resistance, but by current squared:
C 2 R is the measure of the heat. So unless the conductor
is ample to conduct all the current possible, shortening it
will induce more current to be produced and to pass, but
because of this will increase the waste by heat.
Resistance depends on the material. If a piece of fine
silver wire and a piece of platinum wire of the same gauge
be put consecutively in a circuit, the silver wire remains
cool while the platinum becjomes heated : for it has not more
than an eighth part of the conducting power of silver, that
is it resists the current nearly eight times as much. And
if the current is made stronger, this metal, so difficult to
melt or oxidize, may be burnt away: the current has found
the path offered by the condensed air on the platinum
obstructed in some way.
Lord Rayleigh found that in the case of a mixture of
metals there is a source of something, which he says cannot
be distinguished by experiments from resistance, which is
absent in pure metals. It is in reality resistance, and there
is resistance always in conductors whatever their material,
and it varies according to the material of the conductors:
and as the conduction is on the surface, and in the air skin
on the surface, it is there that we must look for the cause
of the resistance.
Nonconduction we may call absolute resistance, and it
is due to a discontinuity of the air skin on the noncon-
ductors: and there is no difficulty in supposing that the
more continuous the skin the better a conductor would
conduct.
The resistances of pure metals to conduction as compared
with one another say platinum with silver must be due to
difference of smoothness of surface, because the denser pla-
tinum attracts a deeper air skin and should therefore be a
RESISTANCE 113
better conductor; but because its covering is spread over
peaks and furrows, and because the current, with its impetus
to go straight, dashes from peak to peak through the more
resistant intervening medium of uncondensed air, rather
than dip into the hollows of the rough surface, the resistance
is increased, and heat results as a consequence of the com-
bustion of the air: this is the cause of the heating of a
platinum wire on which the air skin is continuous but
uneven, while a silver wire, which offers a conductor
of condensed air both continuous and even on its
smooth surface, remains cool though carrying the same
current.
In mixed metals, neither would the surface be smooth,
nor would the air skin lie evenly, and also would accumulate
in denser patches on the denser material, both tending to
unevenness of conduction and to resistance.
" Narrowing the conductor increases the resistance and
causes heat/' The condensed air on the narrowed con-
ductor is not sufficient for the current, and the superfluous
current compels some of the metal surface molecules to com-
bine with oxygen or other material, and by their contraction
in combining they produce heat.
Heat increases the resistance of pure metals : it first drives
off their condensed air coverings, and then makes it more
difficult for the oxygen of the air to get near and combine
with them. Generally speaking, the resistance of metals
above red heat is increased about forty per cent, for every
rise of a hundred degrees centigrade: and advantage has
been taken of this for the construction of instruments for
measuring the heat of furnaces : the heat is calculated from
the resistance: the greater the resistance to the passage of
a current of a known strength, the greater the heat. Also,
strangely enough, the same principle is applied to instru-
ments for measuring those heats that are almost impercept-
ible, such as that of the moon, which, except with Professor
8
114 RESISTANCE
Langley's bolometer, is not discoverable. But then the bolo-
meter can measure the heat of a candle two miles away !
" When metals are cooled in liquid oxygen their resist-
ances diminish greatly. Dewar and Fleming find all pure
metals to lower their resistance as though at the absolute
zero of temperature they would become perfect conductors.
Alloys, however, show much less change/' The cold in-
creases the solidity, as we may call it, of the metals. Just
as ice at freezing evaporates from its surface and does so
less and less as it becomes colder till, at a certain low
temperature, it can give off no vapour because the attraction
of cohesion of its molecules to one another is too strong for
the heat, at that temperature, to overcome and separate
them: so the cohesion of the metal molecules is increased
by the increase of density given to them by contraction due
to loss of heat, and they are no longer free to mingle and
combine with the condensed air and obstruct the current
by setting up unnecessary action. Also the molecules of
the condensed air are perhaps made to be more ready to
combine and to relieve the current of some work. That the
resistances of alloys are less changed is a proof that they re-
tain their interaction with the current. Their mixed mole-
cules of different shapes must be less controlled collectively
by cohesion, as their want of fit prevents anycloser touch
being brought about by their contraction due to cold, so
their individual freedom is less interfered with, and they
continue liable to be moved by and to obstruct the current,
" The resistance of carbon, on the contrary, diminishes
on heating. The carbon filament in the incandescent lamp
has five times the resistance when cold that it has at a
white heat/' This substance holds the happy position
of having a moderate resistance to conduction of electricity
about three-thousandths that of silver and almost an
indestructibility in the absence of oxygen, which together
fit it specially for use in electric glow lamps. Most metals
RESISTANCE 115
in the same position would melt, but carbon, though it can
so easily be turned to vapour and to liquid when combined
with oxygen, has never yet been melted. We cannot speak
with certainty about the way in which it gives light in the
incandescent lamps, but one of the experiments tried with
the voltaic arc gives one an idea. " The light of the voltaic
arc is due to the incandescence of the carbon particles thrown
off by the poles. The heated air is dark/' The carbon
combines as gas with the oxygen of the air to become car-
bonic acid gas and is used to electrolytically convey the
current. But " the negative carbon point instead of
diminishing grows in length when burning in coal gas/'
Here the carbon gas is not combined with the oxygen and
yet gives light. The current finds it easier to promote
the combination of the hydrogen and oxygen, than that
of the carbon and oxygen, and as the combustion of the
hydrogen and oxygen gives no light, it is plain that the
carbon which was gas becomes solid carbon, and in con-
tracting to do so becomes incandescent that is, produces
vibrations of light. So we may say that the surface mole-
cules of the carbon filament are changed to gas by the action
of the electromotive force, and that immediately on their
liberation they contract to solid incandescent carbon
molecules.
Regarding the light and the conduction of the filament,
we have the following facts to consider and to base an
opinion on. Carbon occludes air in large quantities: the
effluves of substances leave their surfaces as gas: carbon
gas immediately condenses to solid even at our highest
producible temperatures: if we examine the bulb of a
burnt out glow-lamp, we find the carbon that had formed
the filament spread over the lower part of .the bulb it has
not been changed to carbonic acid gas : heat encourages the
effusion of surface molecules. From these facts we may
draw the following conclusions.
116 RESISTANCE
The occluded liquid gases in the carbon filament furnish
the electrolyte for the transmission of the current: the
liquid gases are forced into combination, and contracting
in doing so produce part of the heat of the filament: the
rest of the heat is due to surface resistance : all the heat is
used to expand the surface molecules to carbon gas: these
effused carbon gas molecules immediately contract to solid
carbon molecules, in doing which they produce an amount
of light vibrations almost equivalent to the amount of heat
vibrations expended on their expansion: there is little
difference in these amounts, so there is little heat manifested
under ordinary circumstances, and the bulb is not much
heated.
" Solid insulators decrease their resistance enormously
on heating, and when they begin to melt, or when any
chemical change occurs in them through the action of heat,
they generally are made to act as electrolytes by the electro-
motive force, and they become good conductors/' This
refers, not to metals, but to compound solids, and we must
make no mistake about this, as neither metals nor their
alloys conduct electrolytically either when solid or when
melted. The compound non-metallic substances become
liquid electrolytes when melted, and their resistance to the
current depends on the strength of the chemical cohesion
of the substances composing them, and whether the electro-
motive force employed is sufficient to separate their com-
ponent molecules. But elementary non-metallic solids,
like quartz for instance, do not come under this rule : fused
quartz is an absolute nonconductor.
" A current divides among various paths according to
their easiness/' The current may prefer to spark across
a gap rather than go the round of a long loop, or force its
way along a fine wire. It finds it easier to produce electro-
lysis in the air gases in the gap, than to overcome the
resistance to the same action in the fluid air on the longer or
RESISTANCE 117
too narrow track. When the spark leaps across, all the
electromotive force available is used to produce the effect,
and there is no current left. And when several conductors
are available and are together sufficient to carry the whole
current, it divides among them, the more of it going where
there is the lesser resistance.
Liquids have different resistances according to their
composition, and at the best are only moderately good
conductors. Water offers a good deal of resistance when
pure ; indeed it has been stated that pure water is an absolute
nonconductor, but probably every compound fluid can be
forced into conduction if enough electromotive force is
applied. When the water holds salts in solution there is
much less resistance, and it is due to the greater ease with
which the chemical interchanges can be effected in the
dissolved salts than in the water which has dissolved them.
But in the best of electrolytes as compared with copper that
is to say, with the fluid air on copper the resistance is
very great, and it is greater where there is no mineral in the
solution: in nitric or sulphuric acids, it is at the least a
million times that of copper.
; Fluids are bad conductors of electricity. As all cells
are worked with fluids separating their plates, there must
be some internal resistance. Therefore in considering the
resistance, the internal resistance of the cell must be added
to the external resistance of the conductor/' Seeing that
the resistance of the machine cannot be avoided, the only
occasion for measuring its resistance is when comparing
different machines : beyond this the external resistances of
the circuit are all that practically call for attention, and
these only in long circuits such as those used for tramways
and electric lighting : for the short circuits on ordinary wires
of domestic use and laboratory experiments, there is practi-
cally no resistance.
Mixed gases convey by electrolysis in the same way as
118 RESISTANCE
fluids, only they give much greater resistance. When an
electrical machine is worked, the current does not pass
in a continuous stream between the electrodes, but in
separate sparks: a sufficient electrical force has to be pro-
vided each time a spark passes, before the resistance of the
air can be broken down, for the air gases have to combine
before the current can use them, and it is very much more
difficult to make their molecules combine as gas than when
they are condensed as fluid on a conductor; indeed it is
probably as fluid that the gases combine when the spark
passes, though they immediately afterwards become vapour,
being vaporized by the heat that they have themselves
produced by their contraction on combining. The electro-
motive force puts a strain on them that brings them into
a condition to combine: they join contracting to fluid
dimensions, and also contracting from chemical inter-
cohesion on combining: and the heat produced by these
contractions expands them again to vapour. The first
contraction, which is the more violent, produces the heat,
light, and actinic vibrations of the spark; the subsequent
expansion is nearly equal to it, so but little heat is made
sensible: the contraction on chemical combination is the
part of the process used by the current.
The resistance of the elemental gases and vapours should
be absolute, as they should not combine with themselves,
and no conduction can occur without combination : but
oxygen does combine with itself, and it is not certain that
other of these substances do not do this also. Whatever
may be the case, all gases and vapours offer great resistance.
Resistance, then, may be occasioned in several ways, but
in every case it is due to a diverted action of electrolysis.
DISCHARGE
CHAPTER XVI
ELECTRIC WIND AND GLOW DISCHARGE
IF we electrify an insulated body and leave it to itself, after
a, time the charge disappears, it is dissipated, and the body
is discharged.
Some of the charge always manages to leak by conduction
over the surface of the support, which, whatever its material
may be, is not in itself an absolute nonconductor, and also
the support collects on its surface dust and damp both of
which conduct, and it may have been carelessly cleaned and
scratched, and the scratches form conducting channels.
Some of the charge is conveyed away through the air.
Perfectly dry and clean air does no convection, nor any
conduction except under pressure from exceptional electro-
motive force. But the atmosphere is never naturally
perfectly dry or clean, and its dust particles, and perhaps
its vapour, take little charges which they convey away from
the electrified surface.
If there is any point or angularity on the body, it will
discharge the electricity quickly. The electricity seems
to be driven from the point as a wind : and this wind draws
the vapour and dust-laden air over the electrified surface,
and the floating particles take their small charges and fiy
away to discharge elsewhere. If the body has no points,
the main part of the charge is lost through induction, which
is a phenomenon which we will consider separately in
another chapter.
In whatever way the charge may be dissipated, its loss
is from quick to slow like heat: the more nearly the body is
119
120 DISCHARGE
exhausted, the more slowly it gives up the last remnant.
But this is almost the only resemblance that there is between
electricity and heat, and it is only in the case of insulated
bodies that there is this resemblance : and the cause of the
resemblance is that in both cases the molecules have been
put under a strain from which they recover vigorously at
first, and after that more and more slowly. It is only in
this effect, however, that there is resemblance, for the strains
are quite unlike. Heat expands the molecules and their
cohesion of composition contracts them: electricity puts
an electrolytic strain of separation upon the components
of the molecules which their cohesion of composition opposes.
There is probably never any conduction of electricity
from a small insulated charged body in air except over the
support: it is only where there is a large densely charged
body, like a mass of cloud, that the atmosphere can be forced
to become an electrolyte and to provide a conducting route
for the discharge. The air then conducts in the same
manner as the fluid in a voltaic cell : it is composed and
decomposed along the track of the current, and the result
of the burning of the air is left in the current's track. It is
the same also with the spark from a machine: it leaps
across the gap, forcing the air into that chemical combina-
tion without which conduction is impossible, and the
contraction of the combining molecules produces the
vibrations of the light and heat of the spark. It is these
violent passages and those more silent ones from points
that are what are generally meant when discharges are
spoken of.
It is not necessary to say more about the silent electro-
lytic leakage on the supports, or convection by dust and
damp, so we will go on to examine the other modes of dis-
charge, beginning with that from points, which varies from
what may be called a quiet leak to a bright fizzing brush.
If we fasten a needle, by its head, to the conductor of a
DISCHARGE 121
working electrical machine, or a charged Ley den jar, or
electroscope, or in fact any charged body, and place it in
the ray of light coming through a chink into a dark and
dusty room, we will see the dust motes flying from the
needle as if it were a tube through which wind was blowing :
or if we blow some smoke gently about the needle, the same
appearance of wind driving the smoke away from the point
will be seen : and a lighted candle held in front of a point on
the conductor of a machine in full work, is strongly blown
away from it. In whatever way the experiment is tried,
it is easy to see that there is certainly a wind.
There is a scientific toy that shows this action of the
" electric " wind very prettily. It is called the electric
whirl, and is made of six or eight light wire spokes, pivoted
on an upright conducting wire, and with all the spokes
pointed, and similarly bent at right angles near their ends
in the plane of their rotation. They revolve in the opposite
direction to that in which their ends point.
The follo\ving are some extracts giving the opinions of
the several writers regarding this wind.
' The electric charge produces a wind, and the electric
wind produces a charge."
" Electricity itself flows away through the point/'
" When electricity of a high potential discharges itself
on a pointed conductor by accumulating there with so great
density as to electrify the neighbouring particles of air,
these particles, then flying by repulsion, convey away part
of the discharge with them: such discharges are best seen
in air or gases exhausted by the air pump/'
" The electric density at a point is very great, and the
particles of dust and moisture are repelled and bear away
with them the neighbouring air/'
Something is happening on the surface of the electrified
body. There is a strain acting on the molecules of its con-
densed air coat which gives them a tendency to electrolysis.
122 DISCHARGE
Upon the body of the conductor the cohesion of its mass
holds down the molecules of the air coat and resists the
electrolytic action, but at the needle point there can be but
little attraction of cohesion towards the metal to interfere
with the electrolytic action : and at the point it is therefore
more vigorous, and molecules are set free : and the molecules
that are set free by the point expand sixteen hundred times
in changing from liquid to gas, and so make a wind from the
point, and the wind is continuous because other molecules
of condensed air are continually drawn away from the body
and towards the point. It is impossible to condense the
explanation into an anagram, as one of the writers above
quoted has tried to do, but is there need of more than is here
given, or may we say " rem acu " ?
There is no difference in the electric strain, or density,
as it is called, on any part of a conductor, but only a differ-
ence in cohesive attraction of the material of the conductor
due to its shape : and there is no electricity in the electric
wind of itself, because the electromotive force that caused
it was expended on the work of separating the molecules:
but the wind draws the dust of the air into contact with the
conductor, when each dust mote receives a charge and flies
away in the wind with it to get rid of it elsewhere. The
action on the conductor, produced by these dust motes,
no doubt greatly encourages the electrolytic movement, so
that the dustier the air the brisker should be the wind.
If the electric whirl, which was mentioned on the previous
page, " be enclosed in a well insulating glass case, the
rotation soon ceases, because, in these circumstances, the
enclosed air quickly attains a state of permanent electri-
fication." Bodies are said to be electrified when the mole-
cules of their liquid air coverings are put under an electro-
lytic strain, and without such covering they cannot carry
electricity, therefore as the molecules of air cannot be in
a condition to have electrolytic coverings air cannot be
DISCHARGE 123
electrified. The cause of the stopping of the whirl is twofold :
the restriction of the expansion to gas of the air coat mole-
cules, and the loss of the stimulating dust, all of which has
become attached to the sides or fallen to the bottom of the
case. Relief of pressure increases the wind action and in-
crease of pressure lessens it: lacking the dust the discharge
and the movement cease, as may be proved by filling the
case alternately with pure dry air and with air from the
room. With the room air the motion is renewed, with the
clean air there is no renewal of motion.
There is no electricity given to the expanding gas mole-
cules, nor to the air that they carry with them, and it is not
to them that the wind owes its power of giving a charge to
any object that it strikes against, but only to the convection
done by the impurities carried in the air which take their
charges from the electrified body: that is, that take on a
strain in their coatings which they get rid of elsewhere as
soon as they can. The wind is a true wind caused by the
successive expansion of the liquid gas molecules to gas, but
it is not an electric wind as it has no electricity in itself,
but only on the motes that it carries with it.
When the amount of electricity on the body is increased,
the discharge becomes visible in addition to causing a wind,
and what is called a glow discharge will then come from
the point and will extend from it a little way into the air.
The glow is due to the action of the electric current in
causing the combination of molecules of condensed air from
the conductor amongst themselves, and of these with mole-
cules from the metal of the conductor: the air gas and
metallic gas molecules are driven to the end of the needle
by the current, and losing cohesion to the point through its
want of mass, they fly away as gas and some of them com-
bine chemically. The glow is therefore always coloured
124 DISCHARGE
by the vapour of the metal of the conductor. As these
molecules are few in number and are in the double act of
expansion to gas and contraction through conjunction,
they can give but a pale light from their contraction, and
are cold on account of their expansion. The expansion of
molecules always requires heat, and their contraction
always produces it, but in this case the heat required is more
than the heat given, so all the aether vibrations produced
by the contraction are used up in the expansion from liquid
to gas (except some few light vibrations which are of no use
for producing expansion) and the glow discharge is cold
because it wants more heat than has been given to it.
This is a point to be particularly noticed, because spark
discharges arc commonly accompanied by heat.
" When the positive and negative glow discharges come
from fine points, there is a glow on each, and if the points
are in air, there is hardly any difference between them:
but if the discharges are from rounded terminals, the
negative glow is quite poor and small compared with the
positive/'
" If an earthed point be brought near a large positively
charged ball, a star forms on the point and becomes brighter
the nearer it is brought, but otherwise does not change until
it almost touches the ball." The discharge from this point
is negative.
" If the ball is charged negatively, the point has at first
a star, which changes to a brush, and to a spark when
close." This discharge is positive and is, as one can see,
very different from the negative discharge.
' The negative glow often has a dark space at the con-
ductor, especially in rarefied gases in vacuum tubes/'
And from this kathode oxygen molecules appear to be
discharged in vacuum tubes.
All these differences of the two glow discharges point to
their being made up of materials acting differently. We
DISCHARGE 125
must entirely free our minds from the common idea that
electricity has any heat or light of itself: all the light and
all the heat in any discharge is due to chemical action on
material. " The discharge through gas resembles electro-
lysis/' and the light and heat are due to the combining
of the material, just as is the case with any other light or
heat that ever occurs. Now, if the difference between
the positive and negative discharges in air is the action of
" driving the negative electrolytically in one direction and
the positive in the other/' as it surely is, then for negative
and positive we may substitute oxygen and nitrogen in
the above sentence and say, that the difference between
positive and negative discharge in air is the action of
driving oxygen electrolytically in one direction and the
nitrogen in the other. The glow at the positive point
would therefore be a combination of oxygen with metallic
surface molecules, and with nitrogen with the oxygen
continually added: and the glow at the negative point
would be combination of oxygen and nitrogen, with nitrogen
continually added. The dark space in the vacuum tube
at the kathode is a space from which the oxygen has been
rejected, and is a collection of nitrogen which remains dark
because it has little to combine with to produce contraction
and light.
Rarefaction, for three reasons, greatly aids the production
of the glow discharge. First, because the gaseous state is
more easily attained by the discharged molecules; second,
because the surface molecules separate more easily; and
third, because electrolytic movement is made easier.
Faraday, in his investigation of this subject, made some
curious experiments with charged conductors in rarefied
air. He charged a brass ball positively, by induction, when
it was in the beii of an air pump and under an eighth of an
atmosphere pressure, and it became covered with a patch
of glow over an area of two inches in diameter: he next
126 DISCHARGE
succeeded in covering the whole ball with the glow: and
with a smaller ball the glow at once covered the whole and
became brighter and " stood up like a low flame half an inch
or more in height/' On touching the sides of the bell, this
lambent flame took the shape of a ring like a crown to the
ball, appeared flexible, and revolved slowly, the light being
stronger opposite the finger touching the bell. The light
was stronger opposite the finger owing to induction, and
all the rest is explained by what rarefaction does to help
the discharge, except a slow motion of revolution which he
mentions : it is not clear why the bright part should go round
" four or five times in a second/' unless he moved his finger
round the bell.
Induction is an endeavour by the two different electricities
to approach and cancel one another. The St. Elmos' fire,
seen occasionally on the mastheads of ships, and the various
electric glow phenomena observed on the rocks, and on the
heads and fingers of climbers on mountain tops, are all in-
duced discharges of electricity from points that are too far
away from the oppositely charged cloud masses to allow
of a connecting spark discharge. The water on the wet
masts, or on the rocks, and the moisture on the body,
serve as conductors till the air is reached, when some mole-
cular action of combination is set up which produces a glow :
the electricity, having changed to this work, is lost.
When the electric discharge becomes stronger the glow
changes to a brush, which will be part of the subject of the
next chapter.
All the actions of discharge from points the wind, the
glow, and the brush have been ascribed to the repulsion
of electrified floating particles by the similarly electrified
point. But the number of floating particles in the air is
much too small to have any wind-raising effect, and besides,
DISCHARGE 127
whatever it is that repels like electrified bodies, the action
is at right angles to their surfaces, and the more strongly
electrified body more strongly controls the direction : so that,
except in repelling a niote from the very apex of the needle
point, repulsion does not appear to have much to do with
these discharges in which most of the action is in the same
direction as the point. Still the direction of the flight of the
motes may be first started by repulsion arid afterwards
changed by the action of the wind.
In all the discharges of this sort that have been analyzed,
there have been found combinations of oxygen with nitrogen,
and the colours of the discharges denote combination of
oxygen with gas molecules of the metals of the points.
DISCHARGE
CHAPTER XVII
BRUSH AND SPARK DISCHARGES
WHEN a stronger charge of electricity is given to the con*
due tor,, the glow gives place to the brush. Brush discharges
can be made from both electrodes, the positive being longer,
and the negative more easily formed. The positive brush
begins at the conductor as a short bright stalk, which divides
into short branches, and there is a crackling sound, and a
wind in the same direction as the brush. The negative
brush is smaller, less bright, and generally attached to the
conductor without a stalk, and more like a star.
When the brushes are examined with Wheatstone's
revolving mirror, they are seen to be dotted with a succes-
sion of minute sparks. The brush is best seen when it cornes
from a round-ended conductor, and the same charge that
will produce a glow from a point will often produce a brush
from a knob.
Whatever may be the shape of the conductor, it is
damaged by the brush, spark, or flame discharge, and
blunt conductors suffer most: small particles of the metal,
ranging from molecular size to palpable dust, are torn off,
and the conductor is left rough and pitted. Each of the
larger particles carries away with it a coating of condensed
air, and the molecular ones become gaseous and unite with
the gases of the air coating, and in flash discharges are dis-
persed between the electrodes and assist the air molecules
in the transfer of electricity. The light of the brush is
coloured by the incandescence of these metallic vapour
molecules. These are the little sparks seen with the re-
128
DISCHARGE 129
volving mirror, and the glow of the brush, in which they
are mixed up, is from the feebler light produced by the
compounding air molecules.
The light in these, and in all cases, is from chemical
combination. One or other (or both) of the gases, oxygen
or nitrogen, is thrown off from the conductor mixed with
metallic vapours, and these combine together, or with the
air, to produce the light of the brush: its crackle is also
due to this combination: and there is no electricity in the
brush itself, though there may be in what it carries with it,
because the electromotive force is expended in moving
these gases and is thereafter lost as electricity. There is
.no such remainder after any action as work plus result : the
work is expended and the result alone remains.
Whenever the excitation is strong enough a spark passes
between conducting bodies. It may be of any length, from
the lightning flash of several miles to the minute crackle you
get from a cat's back and which you can only see indistinctly
in the dark. It is a chemical combination produced by
reaction from the electromotive force, or electrical potential,
as it is sometimes called.
The voltaic current has little electromotive force, and
Mr. DelaRue, with eleven thousand cells in battery, could
only obtain a spark two -thirds of an inch long, and with
this sort of electricity, to produce a spark a mile long, would
require, it has been calculated, a thousand million DanielFs
cells : while with a single statical machine turned by a small
boy, a spark of a foot long can be obtained, because of the
greater force developed. It is evident, then, that the pro-
duction of the spark and the distance it can cross, both
depend, other things being unchanged, on the electromotive
force. It is the electromotive force that compels the gases
and vapours of the air to separate and recombine and carry
9
130 DISCHARGE
on the electric current: and unless it is strong enough to
produce this electrolytic effect in the air for the whole dis-
tance between the conductors, no spark passes.
When a conductor is discharged by another conductor
at a certain distance from it, the spark lasts for a very short
time one twenty-four thousandth of a second and then
in place of it we have a brush. But if we decrease the dis-
tance between the conductors, we can get a fresh spark but
smaller than the first, and we can repeat this, getting less
and less discharge each time, till by contact the last of the
charge is freed. Apparently the strain in the condensed
air covering of the charged body does not find the time
allowed by the spark sufficient for complete relief.
" When a spark has passed it is easier for a second spark
to follow in its track: probably the first spark produced
chemical changes in its path that do not immediately pass
away/' It is not however the chemical changes, but the
effect of the chemical changes that help on the second spark.
Every spark produces chemical changes giving light and
heat ; an increase of heat makes chemical change easier : so
the next spark passes more easily along the heated track : not
because of any compounded material left by the first flash,
but because of the less resistance to chemical action making
the way easier. Some photographs of lightning flashes
have lately been published by " Knowledge/' and one of
them shows what looks like a ribbon of twenty or more
bright threads the storm has carried the track of the
lightning across the face of the camera, and the lightning
has used this one moving track for these discharges, which
have been consecutive because the cloud has not had time
to send all its electricity at once to the discharging point.
" Perfect vacuum is perfect insulation/' because there
is no material in it for chemical action, and such chemically
acting material alone conducts: but it conducts better for
being made more ready to act.
DISCHARGE 131
" An increase of pressure increases the resistance of air/'
Here again we see the condition of the air determining the
passage of the spark. The electric force has to produce
a certain condition of the molecules before they can unite
and propagate the current, and pressure, by increasing their
density, increases their resistance to change.
Sparks are more easily formed under relief of pressure,
and " sparks are longer and straighter in hot air than in
cold: and when a compound gas is heated to its point of
dissociation, the discharge occurs more easily/' We can
easily understand this: the electromotive force that was
not strong enough to affect the unprepared molecules
has now so little to do that it easily makes its electrolytic
way: the train of molecular conductors is more easily
formed and acted on.
The length of the spark then depends firstly on its force,
and secondly on the reduction of the resistance of the
medium. But its brightness has much less to do with
these than with the quantity of electricity in the discharge.
A strong potential can force a passage for a small quantity
of electricity, but its course will resemble a thread: while
if there is just sufficient force to secure a passage and an
ample current, the display may become a fine flame. On
account of its amplitude of current the voltaic spark is
always brilliant, and even under distilled water, when its
electromotive force must be much reduced, it is still
brilliant. But do not let us forget that the brilliance is
not electrical, but depends on the chemical combination
of oxygen with some other material: it depends in fact
on combustion. " If a powerful current is passed through
two iron bars touching in water, the kathode becomes
covered with a luminous layer and becomes red hot " :
the iron is combining with the oxygen of the water, and
the combustion produces light and heat.
" Discharges in gases have specific character according
132 DISCHARGE
to the gas. They are obtained in nitrogen more easily
than in any other gas/' This is odd, as we do not know of
any combination of nitrogen with itself resembling ozone,
and experiments should be made to find out whether
argon, or any of that class of gases, is produced. If no
oxygen or metallic vapour is present, then some composi-
tion of the gas itself must take place, otherwise there could
be no conduction.
" If the spark passes in dry hydrogen, nitrogen, or in
vacuo, there is no difference between the heat and light
produced whether the metals are oxidizable or not or which
is used for anode or kathode." The vacuum here spoken
of is rarefied gas: if it were perfect there could be no gas
and consequently no discharge. The rarefied hydrogen,
nitrogen, and air conduct the spark by electrolysis in some
way, and that they do so must depend on one or more of
three methods : either the gases combine in themselves :
or the gases combine with the metallic vapour of the elec-
trodes; or the apparatus was not cleaned of its coating of
condensed air and this supplies the electrolyte. In some
way the electricity is provided with an electrolytic bridge,
without which its passage is impossible. From what is
said, in the above quotation, about metals, one might be
led to suppose that the electrodes are not acted on by the
current, but in general in these cases the light is coloured
in such a way as to show that there is vapour of their
metals mixed with the gas. In the case of hydrogen a
hydride is formed, and perhaps the chemists will tell us
whether nitrogen can act on metallic vapours without
oxygen.
" Iron in air or oxygen gives a brilliant arc, but in
hydrogen or a vacuum, with the same power, only a feeble
spark at the moment of disruption. Mercury in like case
gives a spark more nearly approaching what it gives in
air/' The iron, when it had to depend on its condensed
DISCHARGE 133
air covering for effecting a passage for the current, could
make but a feeble and momentary spark from want of
material, as it is not a dense metal and can attract but a
thin coating of air: while the mercury, which is one of the
heaviest of metals, nearly fpur times as dense as iron, must
have a thick covering and would besides help with its
vapour which is easily produced.
" The more near to points in shape the contiguous ends
of the conductors are, the more easily is the spark dis-
charged/' The molecules at the point are cast loose as
vapour by loss of cohesion, and assist the conduction
through the air, and the potential is increased by finding
less resistance. Thus in two ways a point helps the electro-
motive force in breaking down the resistance of the air,
while neither of these actions can occur to any similar
extent on a rounded conductor, on which the condensed
air is pretty evenly tied down by cohesion.
" Actinic waves falling on a point assist it to discharge /'
They make the molecules of air and other materials at the
point more ready for chemical change, and so causing them
to offer less resistance, the electromotive force finds less to do.
" If a wire be attached to a charged body, and the other
end of it put in a flame, the body is discharged and cannot
be charged so long as the end of the wire is in the flame/'
The moment that anything that can conduct and is un-
charged touches a charged body, it shares the charge if
insulated, and if not insulated carries it away. The con-
densed air coat on the charged body is under a strain, and
relieves itself, on contact with another uncharged insulated
body, by transferring to its air coat a part of its strain,
and when the wire, in this case, which has taken on the
electric strain is put in the flame, its electricity finds there
many molecules in the act of combination, and to them
it can pass on its action, and by so doing drain the charge
from the body.
134 DISCHARGE
A point that we must constantly keep in mind is, that
chemical combination is essential to the production and
conduction of electricity and not decomposition or dis-
sociation. Decomposition may precede combination, but
combination, or some movement equivalent to it, is the
action that produces and carries on the electromotive
force. It is often stated that the air, or a wire, or some
other thing, acts as a conductor, with the inference that
the electricity uses them as though they were tubes quite
inactive and quite unaffected by the current. This is a
deduction from a confusion of ideas and quite wrong. Elec-
tricity must in every case have a chemically active con-
ductor, whether it be fluid, or gas, or condensed air on a
solid, and even the surface itself of a metallic conductor
is usually chemically acted on, and without chemical action
there is no current. So if ever we are puzzled for a moment
by some specious explanation, let us think of this and use
it as a touchstone, and if it gives no confirmation, then we
may reject the idea.
DISCHARGE
CHAPTER XVIII
CHEMICAL ACTION OF DISCHARGE
" THE spark discharge, when more than half an inch in
length, is a main unbroken line of light between the con-
ductors,, with forked branches which terminate in the air
between. The main line follows the main stream of par-
ticles and the branches exhaust their energy in the more
thinly scattered particles at the sides and so disappear/'
From this one would suppose that the conduction of the
spark between the conductors was entirely due to the bits
of metal torn off from their ends : but beyond helping the
air somewhat these particles do no good: rather they do
harm, for it is through them that the branches break away
and electricity is wasted. They are small charged bodies
and some of the electricity is enticed away to follow lines
of these wanderers, and after it has caught them, the
branch can only waste its force in the air and disappear
in change to heat. The main line uses the air as its prin-
cipal electrolyte, and always, when there is a disruptive
discharge, the fact that the air is acted on is made sensibly
plain by the smell of ozone and nitrogen compounds, the
taint that these give having long been known as the
electric smell. The electromotive force acts to combine
the mineral vapour molecules and to use them also, for
the spark is tinged with the colours of their incandescence;
but the main carrier is the air, and the measure of the
volume of its oxygen absorbed is the same as would be
liberated by the current in an electrolyte in the circuit*
The branches always point to the negative electrode,
135
136 DISCHARGE
and this is one of a few apparently unexplainawayable
circumstances that seem to prove that there is one current
only, and that it passes from the positive to the negative
pole from the anode to the kathode. It is not as if the
branches took a devious way but eventually reached the
whole way across: they start towards the kathode and
wandering from the way are lost without having any sort
of connection with it. There can have been only positive
electricity in these branches, and no reverse current
possible, nor any chance of negative electrical action in
them.
The positive end of the spark is both brighter and hotter
than the negative, and also it has been found that the
consumption of metal is almost entirely at the anode, and
that the length and brilliancy of a spark, in an oxidating
medium, depends on the oxidability of the anode, while
the kathode may be made of platinum, or carbon, or any
unchangeable metal, without dulling the spark. In fact
the oxygen of the air in contact with the anode assisted
by its air coating and metallic vapours forms the starting-
point of the track of the spark.
" With the kathode cooled and the anode heated no
current passes/' By cooling the kathode the condensed
air on it is certainly made to attach itself more strongly
and so to resist action, but it is by the heating of the
anode, which dissipates the air attached to it, that the
action is stopped. It is almost equivalent to putting the
anode in a vacuum: nothing can come into touch with it:
no chemical change can occur on its surface, so no current
can pass from it.
" The negative discharge in air is seven or eight times
more frequent than the positive, but with far less electric
force. The negative discharges with a lower tension/'
The oxygen is combining with the anode to produce the
electromotive force, and there all the resistance originates:
DISCHARGE 137
while at the kathode there is no action nor resistance but
what is due to the slight cohesion of the liquid gases to
the metal.
Electric discharges in tubes are merely ordinary dis-
charges complicated by using particular gases or vapours,
particular electrodes, and much relief of air pressure, and
magnetism is occasionally thrown in to increase the com-
plexity. The tubes are called vacuum tubes, but should
be called rarefied tubes as a vacuum is unattainable. In
a true vacuum no electric phenomena would be seen as
no current could pass. Some of the colour effects in
Geissler's tubes are remarkably pretty, and they teach us
that some of the metallic molecules have been forced by
the electricity to unite as vapour with the gas in the tube,
giving out by their contraction in doing so the vibrations
that produce the characteristic colours of their rays.
" In a vacuum tube the colour of the light differs according
to the metal of the electrodes, proving that the separated
molecules are gaseous/' The colour also depends on the
gases used. " The conduction in gas is electrolytic/' and
it is this combination that allows of conduction through
the tubes and that produces the light and colours.
But this is not the opinion of all scientists: here is another
explanation. ' The luminosity of rarefied tubes is due to
dissociation and impact of molecules in addition to oscilla-
tion of electric waves/'
Dissociation is separation, and separation gives relief
from cohesion, with expansion and cold. Impact might
produce light if it forced the molecules to combine, because
they would then contract and produce aether vibrations
in doing so; but evidently this is not the meaning as
separation is spoken of. And the electromotive force has
110 light of itself, because its waves even though they can
affect the aether are very much too large to produce
light vibrations in it.
138 DISCHARGE
What may be called electric waves, that is the aether
vibrations of the electromotive force, in their encounter
with material can only act mechanically on the molecules:
their peculiar action, so far as we have seen, is to electro-
lytically drive them apart: and if the molecules respond
very vigorously in recombination, they produce light or
higher vibrations: if with less vigour heat: and if with
less vigour still, they reproduce electric waves. The
luminosity of the tube is a modification of the spark in
air: the difference is that in the tube the molecules are
much more expanded, and their contraction in compound-
ing is consequently so much more violent that they can
only produce for the most part those higher vibrations
that are light-producing or actinic: and because they are
few in number, their united light is feeble.
" The discharge in the Torricellian vacuum has a feeble
light which is increased by heat/' If a six-foot glass tube,
of the gauge of a barometer tube, be bent in the middle
so as to form a long loop with parallel sides joined by a
semicircular head: and if it be filled with mercury and
then inverted with the two ends in cups of mercury: the
bent part will contain a Torricellian vacuum: and if a
discharge is sent through it from wires dipping into the
cups, the vacuous space will give a white glow. This light
is from the vapour of mercury and a small quantity of
air drawn from the surface of the glass which are acted on
electrolytically by the current. If the bend is warmed
the brightness of the glow increases, because both the
amount of mercury vapour is increased and also the amount
of air liberated by the glass.
Many curious effects are produced by varying the
action and the shape of vacuum tubes, most of which
would require a separate explanation with much repetition
that would tell us nothing that we have not heard already,
so we will only notice two effects. One of these is the
DISCHARGE 139
production of striae. With a certain amount of exhaustion
the luminosity is divided by dull bands throughout nearly
the whole length of the tube even when it is several feet
long : the bands nicker about or pass slowly to the kathode,
and they are almost perfect examples of stationary waves,
the length of the wave being the distance between two
bands. The negative discharges occur oftener than the
positive, and their comparative rate is apparently con-
trollable by the relief of pressure, and when a particular
limit is reached, the negative by giving two discharges to
one of the positive, produces an alternate combination and
interference between the waves of the electrolytic current
in the tube: the combination produces the bright bands
where the electromotive force is more active and where
much of it is wasted changed to light and heat : the darker
bands being the interferences where all the force that is
left is used in causing electrolytic action with which to-
carry on the current. Examined by Wheatstone's re-
volving mirror the striae show a succession of minute
sparks which are due to the violent recombination of the
molecules.
The other effect can be seen in another form of these
tubes, which is pear-shaped. The anode is placed at one
side, and the kathode, which is a slightly concave disc,
at the small end. With a strong current and very high
exhaustion the oxygen molecules appear to be shot, from
the surface of the kathode to the broad end of the tube,
where, on striking the glass, they produce phosphorescent
light. In some of this sort of tube there is a little Maltese
cross of mica which intercepts the action and, by shielding
the glass, produces on it an apparent shadow. And some-
times there is a little paddle wheel to show by its move-
ments the force of projection of the molecules.
W T hen more moderate exhaustion is used, and with a
saucer-shaped kathode, the discharge of oxygen in these
140 DISCHARGE
tubes can be concentrated at a point and will produce
enough heat to make a platinum wire placed there red
hot.
We must bear in mind that the current flows through
both wires, and that all electrical movement is effected
by electrolysis : and considering these facts the explanation
of the above phenomena will not be found so simple as
the effects would lead one to suppose.
The oxygen molecules, being material, have certainly
acquired inertia of motion, but there is nothing to show
that they have traversed the distance between the kathode
and the glass as independent projectiles. They have
moved in the usual electrolytic way, and being few in
number, from the high exhaustion, they have moved
comparatively quickly, perhaps as much as a quarter of
an inch in a second. Their inertia, and the particular
shape of the kathode, have caused them to move in a
parallel stream at right angles to the face of the kathode.
When these molecules reach the glass, they condense to
liquid upon it, but immediately become gaseous again,
as they are in excess of the condensed coating that the
glass can retain: and they then pursue their electrolytic
way towards the anode.
Because in these tubes there is this negative oxygen
discharge and no apparent equivalent nitrogen bombard-
ment on the kathode, some physicists say that there is
negative electricity only, and no positive. But because
it is not perceptible is no proof that there is no movement
in the nitrogen. The nitrogen molecules are four times as
numerous as the oxygen and are lighter, so they must receive
much less impetus: and more recent experiment has shown
that there is a faint light made by the condensation of
the nitrogen molecules on the kathode disc, and when a
hole is cut in the middle of the disc, it is seen that the
nitrogen molecules stream a little way behind it owing
DISCHARGE 141
to their inertia. The feebler light they give is due to their
feebler action and lack of material to combine with.
In the body of the tube there is no movement perceptible
either way, but only at the terminations of the stream of
molecules, and as the movement of the oxygen is deduced
from the light given off on the glass, so also we must
conclude that the nitrogen moves because it also gives
light though more feebly for the reasons given and both
gases move electrolytically.
In every case where light and heat are produced they
come from contraction of molecules, but the contraction
may come about in various ways. When a current meets
with resistance in passing over a conductor, or through air,
or an electrolyte, we find that the electricity and the
contraction must be nearly related. The electricity acts
on the molecules and forces them to assume a position
in which their natural power of cohesion is able to recom-
bine them, and the contraction due to this combination
produces the light and heat. The light is brilliant, but
in the case of the spark in air the heat does not appear to
be very great: an inflammable substance like ether may
be set alight by it, but it will not fire gunpowder, which
is blown about by the spark. Evidently there must be
many light vibrations in the spark and few vibrations of
heat. " The spark from a Ley den jar will scatter gun-
powder without firing it unless it is passed through a wet
thread or other resistance/' The undamped force has
so violent an action on the conducting molecules that
their recovery is also violent, and they only produce those
short vibrations in the aether which occasion light but
are devoid of heat-producing power : while with the damp-
ing string included in the circuit the force is reduced,
and some of the reproduced vibrations are then those
longer ones that cause heat.
The discharge of frictional electricity is always confined
142 DISCHARGE
to as narrow a line as possible, for there is but little current,
and to spread it into a thick column of air would exhaust
the electromotive force unnecessarily. This electricity
finds its way by acting on as small a quantity of material
as it possibly can, and it goes far along a narrow track.
With voltaic electricity broad flames can be produced,
for there is abundance of current, but they do not carry
far because the electromotive force is wanting.
The noise made by the discharge is the wave of disturb-
ance of the air by the expansion that accompanies the
discharge.
There is a scientific toy that shows this expansion of air
very well. It is a small glass mortar, shaped like the
military cannon of that name, and in it are two wires
ending in small knobs. When a spark is passed between
the knobs, a ball, resting on the mouth of the mortar, is
shot up by the expansion of the air. We say here by ex-
pansion of the air, but we need not take it for granted that
the molecules of the air are expanded in the same manner
as they are by heat, or through any heat of the spark.
Heat can expand a compound molecule without in any
way dissociating its chemical components, but the current
can only act by dissociating the components with every
wave. Now the components of the compound molecule
are bound together and contracted by their mutual cohesion,
and when separated they every one of them expand, and
it is this expansion that drives the ball off the mortar.
In expanding they require heat, and in contracting again
give up as much, so there is neither cold nor heat displayed.
This expansion of material by electrolytic action may
be shown in other ways. For instance, the bursting of
a glass tube filled with water by -a discharge sent through
it, and if a card is put between two points and a spark is
DISCHARGE 143
passed, a hole, with ragged edges that project on both
sides, is made in the card by the expansion of the air in
the track of the spark through the card. Glass may also
be perforated in the same way, but the discharge must be
a strong one. The glass in the electric track is reduced to
powder, because the composition of its molecules has been
broken up and the cohesive force of the separated atoms
is not sufficient to bind them together again. This ex-
periment sometimes fails from the electricity passing
round the edge of the glass plate, and if it has once done
so, it is useless to try again with the same piece of glass,
as the current will always follow the same line that it
first took: it has had some effect on the surface molecules
that changes their relation to the condensed air coating.
From what we have learnt in these chapters, it appears
that the electricity on electrodes sets up a strain in the
medium between them, and the spark passes if the electro-
motive force is strong enough to complete electrolytic
movement throughout the whole of the intervening dis-
tance. And the only difference between a discharge in
gas and conduction in a voltaic cell is, that the first needs
more electromotive force, is noisier, and is generally
discontinuous: both are electrolytic.
INFLUENCE
CHAPTER XIX
ACTION OF INFLUENCE
INDUCTION was the name originally used, and still often
used, for the action we are about to study, but it has
since been particularly applied to the induction of currents,
so, to avoid confusion, we will use the word influence
which is being generally substituted for it, and which is
understood to mean the induction or production of charges
by charges. This then is influence. If we give an insu-
lated body a charge of electricity, it will electrify all the
near-at-hand surrounding bodies to a more or less appreci-
able degree.
Influence does not in its action resemble heat, excepting
that its effect diminishes quickly with distance. In heat-
there is exchange between differently heated bodies with
gradual loss and gain: here no part of the original charge
appears to be dissipated by the influence which produces
change elsewhere: and the change in the influenced bodies
is instantaneous. This is unnatural and contrary to our
ideas of work. If the charged body acting through the
intervening medium can disturb other separate bodies,
whether by rods of force, or ejected electrons, or radiant
vibrations, or in any other way, there should be something
working on the charged conductor to produce this transfer
of force, and there should be a continued relative loss and
gain of power. No satisfactory explanation and no exami-
nation of this part of the subject seems to have been under-
taken as yet, though theories have been conceived in plenty :
144
INFLUENCE 145
and yet the discovery of an action on the receiving body
having been made, the description of the method of that
action is surety the first point we ought to know when
studying influence.
If an insulated conductor is charged with electricity in
any way, it induces a charge of the opposite electricity in
all neighbouring uninsulated bodies. If the charge given
to the conductor is positive, the charges produced by its
influence are negative, and vice versa. And these charges
disappear when the bodies are removed beyond the range
of the influence.
If the influenced body is an insulated body, unlike
electricity accumulates on the side of it nearer the charged
conductor, and the like electricity is repelled away as far
as it can go. If now we put this influenced body in con-
nection with the earth by touching it for a moment with
a finger: all its like electricity leaves it and it becomes
charged with electricity unlike that on the conductor.
We can now take this insulated body with its charge of
electricity to a distant part of the room, .and transfer its
charge to a Leyden jar, or dispose of it in any other way,
and then replacing it near the conductor, and touching it
again with a finger, we have it recharged, and we can do
this as often as we wish without apparently lessening the
original charge on the influencing conductor.
Two insulated charged bodies placed near together
react upon each other. If they are similarly charged, their
charges are repelled and accumulate in greater density
on their further sides : and if they are charged with unlike
electricities, these accumulate on their adjacent sides:
and in both cases the nearer they are the stronger the
interaction. With contact dissimilar charges neutralize
one another, and the action ceases if the quantities have
been exactly equal: if any excess remains, this remainder
is spread over both bodies, and when they are separated
10
146 INFLUENCE
they again influence one another, though of course in an
opposite manner and in a lesser 'degree.
The action is similar if one of the insulated bodies is
uncharged, and is put in contact with the charged con-
ductor. The dissimilar electricity, accumulated towards
the point of contact, is neutralized by a part of the charge,
and the two bodies are charged with similar electricity
equal in amount to the original influencing charge: there
has been no loss or gain.
If a charged body is introduced into a hollow conductor,
it induces an opposite and equal charge on the inside of
the conductor, and an equal charge similar to its own
outside. If for instance the influencing charge is positive,
it induces equal negative inside and equal positive outside.
If now the introduced body is put in contact with the
conductor, its positive and the inner influenced negative
charges cancel, and the conductor is left with a positive
charge outside, exactly equal to what would have been
given to it by immediate contact inside or outside.
If two bodies with dissimilar charges of equal intensity
are introduced together, but not touching one another,
into a hollow conductor, they produce no effect as their
effects cancel one another.
When the surfaces of insulated bodies which are under
influence are tested by means of the proof plane, it is found
that they have a coating of electricity which is denser
towards extremities and projections and which is positive
or negative according to the position of the part in relation
to the charged conductor, ' and to the sort of influencing
charge on the conductor ; and the coating of the electricity
on the charged conductor has a similarly arranged dis-
tribution. If we were to draw the outline of this electric
coating on such a conductor as is commonly used for these
experiments, and which has a short sausage shape, we
should find that this outline resembled a light dumb-bell :
INFLUENCE 147
all projections have an accumulation and points draw
the electricity towards them and discharge it as in other
cases. The coating of electricity on the influenced body
entirely disappears on its removal to a distance from the
charged conductor. There has been a separation produced
on the surface of the influenced body by the action of the
influence : and the separated matters resume their ordinary
admixture, or conjunction, or composition, or whatever
it was that was disturbed and driven apart by the influence.
" The passing of a charged rod over an electroscope
causes the waves to flap to and fro but does not charge
the electroscope but if a metal point is added to the bulb,
the rod passed at twice the distance will charge the electro-
scope." What happens when the electroscope is thus
charged is not that the electricity from the rod is poured
into the electroscope through the point, for the rod ap-
parently loses none of its charge, but that by the influence
of the charge of the rod there has been a separation in the
electroscope; the unlike electricity has been drawn by
the influence towards the point which has been unable to
retain it, and it has, as we suppose, been dissipated upon
the dust and vapour of the air and in producing a wind,
while the like electricity appertaining to the electroscope
has remained to charge it. The same result happens if
the glass rod is put in contact with the point: the electro-
scope in both instances is charged with positive electricity:
but the influenced charge is produced by taking something
away, and the conduction charge by adding something.
This is rather puzzling.
We must not, if we wish to charge an electroscope by
influence, bring the charged rod too close to the instrument,
for the rod would certainly empty itself by discharge into
the bulb or point, and the electroscope would then have
a positive charge very much stronger than the charge it
could have got by influence. A well-electrified rod will
148 INFLUENCE -
show all the influencing effect if held nine inches or a foot
from the electrometer, which is a delicate instrument likely
to be damaged by rough shocks.
There are some electrical machines, called influence
machines, which have some outside resemblance to the
plate frictional machines, and which are made to work on
this principle of influence. They require a small charge,
such as may be got by rubbing a glass rod, to start them,
but once in full action they are more powerful than the
static machine, and much more reliable. You have no
doubt seen descriptions of these machines in elementary
works on electricity.
By the influence of a charged body both electricities
are generated in equal quantities, that is to say that the
positive and negative electricities separated on an insulated
body, the one attracted towards the charged conductor,
and the other repelled from it, will be equal in amount.
The amount produced however will in no case be equal
to the influencing charge. For instance, half a dozen
equal-sized bodies surrounding at equal distances a posi-
tively charged globe, could not each of them have more
than a sixth part of a negative charge equal to the positive
charge on the globe, and would in fact have much less,
for, like all radiating influences, distance decreases the
effect in proportion to the square of the distance. Increase
of strength only increases the induced charge in equal
ratio. So the repulsion between two bodies will be the
product of their two electric charges divided by the square
f* X f*^
of the distance between their centres: or -\. 2 - And
this also gives the measure of their attraction if they are
differently charged.
Influence induced by powerful charges is reinforced in
enclosed spaces by reflection from the enclosing walls.
" The alternating charge is distributed upon the opposite
INFLUENCE 149
coatings of the walls, the air between taking the place of
the glass in a Leyden jar. Electric waves fill the air
giving to-and-fro motion to it." The last sentence is
Avrong. The glass in a Leyden jar has no to-and-fro motion
and neither has the air from the influence waves. So long
as the electromotive force on the insulated charged con-
ductor is acting, so long will sether waves be produced
which will no doubt pass to and fro in the room by reflection
from the walls: and they will necessarily act on every-
thing in the room, and in so acting will be destroyed, or
we should say, converted to other work by producing
action on the Avails or other bodies they encounter. But
jt is neither the glass of the Leyden jar nor the air of the
room that is the medium of the induction rays, but the
aether that traverses the air or glass. The stress of the
electromotive force sets up an electrochemical motion in
the liquid condensed air coat of the charged conductor
or surface of the Leyden jar: and this motion produces
radiant induction waves in the sether in the air of the room
or in the glass of the jar: and these aether waves set up
electrochemical motion in the condensed air coatings that
they encounter, and this produced electrical motion on
the surfaces is in the direction of the rays of influence,
that is away from the influencing body, but of the same
electrical denomination, and the reverse electricity is left
to accumulate on the nearer sides of the influenced
bodies.
The charge on a conductor produces in this way opposite
charges on all the objects in its neighbourhood: so when
the conductor is discharged, all the objects that have
received counter charges by its influence are also dis-
charged. This relief of tension is what is called return
shock. It can never be equal in strength to the influencing
charge, nor can it act far, but in lightning stroke it is
often felt a hundred yards or more from the point where
150 INFLUENCE
the lightning strikes, though even when very much nearer
it is seldom fatal.
Influence does not act to any great distance. A cloud
will induce electricity in the earth a mile below it, and
a conductor the size of one's head, charged and placed in
a small room, will induce a small amount of electricity
on any object in the room, but a furlong away from the
land covered by the cloud, or on the walls of a large room
there would be no appreciable effect. It is evident from
this that influence is not of the same nature as the radiant-
Marconi wave which travels to very great distances. The
two Marconi and influence waves are constantly mixed
up in explanations of electrical experiments and actions,
and as no doubt there are many occasions when both sorts
of waves are produced at once, we must analyze descrip-
tions of results very carefully that we may avoid being
led astray.
INFLUENCE
CHAPTER XX
INFLUENCE IS AN JETHER WAVEJ
INFLUENCE waves are produced by local action. Of this
there cannot possibly be any doubt, for no movement
can originate itself, though present-day theorists try to
make out the contrary as regards electricity.
When a body is charged and owing to insulation the
electromotive force cannot escape, influence vibrations
are produced: and we also find that they are produced
when a current is sent along a conducting wire: and as
they are produced by the electrolytic movement on the
wire, we may judge that they must also be produced by
some electrolytic movement on the insulated body.
No mere strain could produce vibrations in the sur-
rounding aether: they could only come from completed
movement: so we are compelled to believe that the mole-
cules of the surface under strain on the insulated body
do complete some slow electrolytic movement from which
the influence waves result.
A glass surface such as the inside of a Leyden jar can
be charged where it is covered with foil, and the electro-
chemical action so set up produces aether waves that
radiate in every direction. Those that radiate inside the
j ar are cancelled : those passing through the glass influence
a similar electrochemical action on the outer surface, the
like part of the charge escaping to the earth and the unlike
remaining. The glass between is sometimes pierced if
too thin: and this has been ascribed to disruptive action
between the charge and the induced electricity on the
151
152 INFLUENCE
outside of the jar: or to the violence of the vibrations set
up in the glass through its being the intermedium between
the inside and outside charges. Such ideas, though they
have a shade of truth in them, lead us quite away from the
real cause of rupture, which is, that the electromotive
force has had sufficient energy to force the glass at its
weakest point into electrochemical action: the glass has
been forced to become electrolytic: its molecules have
been dissociated, and, if they could, would have recom-
bined in just the same manner as any other electrolyte.
Had the glass been a better electrolyte the hole would have
been repaired with slight loss.
It is also said that " the charge strains the surface/'
with the idea more or less definitely expressed that the
strain is electricity. The strain is resistance to electricity:
the molecular resistance of the glass against decomposition
by the dissociating stress of the electromotive force: and
the resistance is not of the surface, but of the substance
of the glass.
The thinner the glass the greater the capacity of the
Ley den jar, because the energy of the influence increases
inversely as the Square of the thickness, but the thinner
^the glass the more care must be taken in discharging, for
thin jars are often spoilt by careless discharge. If the jar
is discharged by a wire touching the knob and the outside
coating at one point, the jar may be broken through there
because the electromotive force must accumulate at that
point, even though it may be but for a twenty-four
thousandth part of a second, and it causes an accumula-
tion on the other side at the same point, and the two
electromotive forces of these two electrodes may find that
they have sufficient accumulated power to overcome the
cohesion of the components of the molecules of the glass,
and take this shorter route. It is to prevent this that
the jars are sometimes filled with crumpled foil, or have
INFLUENCE 153
other devices by which the electricity is drawn from many
points of the inside at once, and they would be made safer
still if some arrangement, acting in the same way, were,
applied outside. But the jars would not be made any
more powerful by these means, for they could not take
a larger charge since it is not the foil that receives the charge,
but the surface of the glass.
" A slab of glass three inches thick has been pierced by
the discharge of a powerful induction coil. A layer of oil
resists being pierced as much as a layer of air five or six
times as thick would be. Toughened glass is less easily
pierced." It is the molecular resistance of the substance
against electrolysis that is the " strain/' and not electricity.
When we charge a Ley den jar, we charge the glass, not
the foil. Experimenting to find out where the electrifica-
tion of the jar lay, Benjamin Franklin made a jar with
movable coatings, and on removing them from the glass
after the jar had been charged no electricity was to be
found on either of the coatings: but on putting them, back
again on the glass, the arrangement was found to be
charged as before. The electricity had been left on the
surface of the glass.
When we charge a Leyden jar, we hold it with our hand
touching the outer coating: the outside must be in connec-
tion with the earth, for no charge can be given to an in-
sulated jar: we present the knob to the prime conductor
of an electrical machine, keeping the two about half an
inch apart, and sparks pass for some time : when the sparks
have ceased the jar is charged, and we can keep the charge
stored, though not for very long.
A very much larger charge can be given to such a jar
than can be given to an ordinary conductor, because with
every addition to the surface we are charging, an equal
addition of unlike electricity is made to the other surface
by the electrolytic action on the conductor from the earth,
and the two electricities have a mutual influence that
154 INFLUENCE
holds them bound to the two surfaces. The action on
either surface is to produce aether influence waves which
give the glass molecules between them an inclination to
move their components electrolytically towards the
surfaces, and it is the cohesion of the glass that resists
the completion of this movement and the conduction of
the electricity. The forces therefore that bind the two
electricities must reside in the condensed air coatings of
the two surfaces. And we find that they act so strongly
that we may touch either surface, and remove no electricity
from it so long as we do not touch both surfaces at once
which we should be very careful not to do as it is dangerous
with a large jar, for you give your body as an active electro-
lytic path by which the electricities escape and cancel one
another.
Influence acts through aether, air, glass, in fact through
any substance unless it is a conductor, or to put it con-
cisely, the worse conductor the better inductor. Charged
bodies repel or attract more through a vacuum than any-
where else : more through glass than ebonite : more through
ebonite than air.
Many experiments have been made with screens set up
between electrified bodies, which, except in the com-
parison of the action of various conducting substances,
are not of much use, for influence can get round a screen
most easily. M. le Bon found that it was extremely
difficult to exclude influence and other electrically pro-
duced aether waves even with metal screens, because they
made their way through the narrowest crevices. So the
placing of a plate of glass in plain air between two excited
conductors does not teach us much.
However some very pleasing and convincing experiments,
which were invented by Vanderfliet, can be made with
wire gauze as a screen, and the apparatus can be easily
made. All that is wanted is a piece of wire gauze eighteen
inches by six, with three pieces of strong wire twelve
INFLUENCE 155
inches long, fastened to it at the middle and ends, so as
to project all of them six inches from one side: fasten the
free end of the middle wire into a piece of glass tube 'on a
wooden foot, and encase the other end ones in glass tubes
which will serve as insulating handles: attach a number
of slips of paper, two inches long, by loops of cotton thread
through their upper ends, along the middle of the gauze
on each side, and the machine is complete.
Electrify a glass rod and scrape its whole length upon
the top of the wire gauze so as to transfer all its electricity
to the wire, arid the paper slips will stand out on both sides
of the gauze: bend the gauze into a ring and the inner
slips fall, while the outer slips stand out further: reverse
the bend of the ring, turning it inside out, and the action
of the papers is reversed: form the gauze into the shape
of the letter S, and the papers stand out from the bulged
sides and droop on the inner sides of the bends. Now
straighten out the gauze, and having electrified a con-
ductor with the glass rod, bring it- near one side of the
gauze: all the near paper slips are flattened against the
wire, and those on the further side stand out: and with
a negatively electrified conductor, the slips point towards
it on the near side and cling to the gauze on the far side.
Anyone who has seen these experiments will not fail to
perceive that the electricity is something belonging to the
wire, and that the influence is something acting in the
medium between the charged bodies.
It is plain that influence must be an action taking place
in the aether, as it acts through a vacuum as well or better
than through anything else: and as the only action that
can go on in aether is vibration, we may safely say that
influence is an aether vibration that has nothing to do
with molecules beyond that it is originated by them and
reacts on them: and being a motion it is only by its effect
on matter that it is sensible to us : and if it is sensible to us,
that it is through the motion of molecules that it is so.
INFLUENCE
CHAPTER XXI
INFLUENCE AND INDUCTION
POSITIVE electricity is produced by the coming together of
molecules: is negative electricity due to the separation of
molecules ? Not likely. There must be a sequence of
alternate molecular action and aether vibration: an act
of vibration between every two molecular actions, and
here there would be no vibration between the conjunction
and separation of the molecules. Negative influence is
as" much a vibration as positive and the separation of
molecules could not produce a vibration. It is not ex-
pansion, or more extensive range of movement that pro-
duces the vibrations that cause light, heat, and electricity
though this was the old idea it is the conjunction and
contraction of molecules that produces these effective
vibrations: and the influence vibrations can only be pro-
duced by the corning together of molecules.
Are positive and negative vibrations two sets, or only
one set divided so that we see one part reversed ? The
positive drawing the acid molecule to combine with the
basic : and the negative pushing the basic to combine with
the acid. Meeting they would act like other waves passing
through without destroying one another: both producing
the same action in the molecules, and merely producing
them from reverse directions.
Following up this idea, it would appear then, that the
coining together of an acid and a basic molecule in a voltaic
cell, or elsewhere, produces a vibration, which the mere
chance of position of the zinc or other compounding
156
INFLUENCE 157
material causes to be propagated, one half through the
acid molecules to the kathode as positive, and the other
half through the basic molecules in the opposite direction
as negative. Practically making them two electromotive
forces, one, the positive driving the basic molecules before
it, and the other, the negative, driving the acid molecules :
and both producing the same chemical action though in
contrary order: and both renewing their force with every
combination of the molecules: and either of these electro-
chemical combinations conveyed to an insulated conductor,
or passed along a connected conductor, producing waves
in the aether which, acting on neighbouring bodies, in-
fluence in them electrochemical action. It seems rather
haphazard. However we will consider this further on
when we have reviewed all the workings of electricity: OUE
present work is with influence only after it has been pro-
duced and is acting.
There is this great difference between influence and
conduction. Conduction is only possible with palpable
material, and depends on the molecules and their electro-
chemical action, and on the electromotive force which sets
up the electrochemical action of the molecules: and it
transfers the electric current, whether positive or negative,
without change. While it seems that influence changes
the electricity, that it depends on the aether for its trans-
mission, and has nothing to do with electricity or material
beyond this, that it is produced by them and can reproduce
electricity in material. Or as Tait says: "The electrical
conduction of matter is entirely different from any action
the molecules may produce in aether. In the aether they
are aether waves no more no less. They are a radiant
energy that the molecules of matter can transform into
electricity/' This could not be put better or more clearly.
What we have found out concerning the action of charged
bodies on their surroundings must prevent our accepting
158 INFLUENCE
all that is given in the following extract from another
author. " The space surrounding an electrified body is
electrified in proportion to the distance from the body,
and through this the electricity is discharged by a flame
which is a number of points. But the magnesium flame
discharges negative influence only/' Air is very resistant
to electricity, and if it could be electrified would conduct
the electricity to the surrounding bodies and produce in
them similar electricity, and not an opposite charge, which
is what influence does. Influence acts across a vacuum
which electricity cannot do, and it is plain that it is a
particular vibration of aether with which the air has
nothing to do.
Conductors of any sort absorb conducted electricity or
the influence vibrations for their own electrochemical use,
and if a point absorbs the vibrations more freely than a
knob, it is because the molecules of the condensed air on
it are more easily acted on, owing to lack of cohesion to
the point, than the molecules of the coating of the knob.
Points, flames, wire -gratings, and any conducting material
in any form, absorb the influence vibrations and are acted
on by them, and as they prevent them from passing any
further they appear to discharge the air of electricity, but
at no time were the vibrations a part of the air.
The influence vibration if produced by positive action
produces a negative action on the influenced body, and
vice versa if the vibration has a negative origin. Hence
ordinary flames, which do not act because they are points,
but because they have several chemical actions going on
in them, can act like any ordinary conductor and accept
either positive or negative influence: but when the action
of the flame is confined to a single composition, such as the
oxidation of magnesium, which may be called a positive
action, it can accept no negative motion such as would
be given to it by positive influence, but only positive
INFLUENCE 159
motion. The ordinary hydrocarbon flame has at least
two coatings or shells, an inner shell in which hydro-
carbon gas is decomposed and its carbon constituent
combined with oxygen, and an outer shell in which the
hydrogen constituent is combined with oxygen to form
water vapour, and between these two it has been found
that there is a slight electrical action: any vibration that
helped this action either positively or negatively would
therefore be absorbed. But in the magnesium flame
oxidation is the whole process: the oxygen molecules are
driven or drawn towards the magnesium, and only those
vibrations that aided this action would be accepted. The
action is one of conduction in the flame and is electrolytic
as in every conduction.
" If a strip of aluminium or gold leaf, cut to a point, is
placed., point up, between a ball kept charged with positive
electricity, and a point in connection with the earth,
three inches below the ball, it will remain suspended at a
certain spot motionless in space, and emit small sparks
from its pointed end towards the ball." This is a very
instructive experiment in which conduction and influence
are both at work. The author regrets that when making
a note of it, he omitted to add the inventor's name, which
should have been given here, with congratulations for having
discovered so excellent an example.
The negative electricity is conveyed by influence from
the earthed point to the strip, and from the point of the
strip by spark discharge to the ball. Being negatively
electrified, the strip is repelled by influence from the
earthed point and attracted to the ball: but if it goes too
near the ball it receives less electricity from the point and
its attraction to the ball lessens and it falls ; and if it falls
too near the point it gains more electricity and is more
repelled from the point by influence: and as the negative
electricity always travels from the more receptive base
160 INFLUENCE
of the strip to the less retentive point, the point does not
change its direction: so the strip retains both its position
and direction in space.
" If the ball is charged negatively, the strip will attach
itself to the ball and will not remain in any position in
space/' The result in this second case would have been
exactly the same as in the first case but for the greater
force of the positive discharge from the earthed point.
The positive discharge is so strong that it breaks down all
the opposition of the influence. In the first case there
were two nearly equal forces pushing against one another
with a strength which decreased with the square of the
distance, and which were therefore capable of having a
balancing point; while in the second case, there can be
no such point, because one of the forces is everywhere
stronger than the other is, even at its place of origin.
When at the beginning of this study we said that the
charged conductor influenced surrounding bodies without
loss to itself, we were repeating what we had been taught,
and which is still taught, but which certainly has not been
sufficiently thought out by the teachers. The charged
conductor is losing electricity all the time, and this loss
has been put down to convection from it by the air, and it
is no doubt for the most part due, not to the air, but to
the impurities of the air conveying it away : but it is an
impossibility that motion should be produced without the
expenditure of work to produce it, and a part of the loss
from the conductor must therefore be due to the work of
production of influence waves. It is impossible to measure
the amount of the influence action on a conductor in air,
but it should be easy so to arrange that a body with earth
connection should be charged by influence in vacuo and
then disengaged and insulated. The vacuum would
INFLUENCE 1(51
prevent conduction, and the body therefore could only
lose its charge by its influence on its surroundings, and the
time occupied in this loss compared with the time in air
would give the amount of loss due to influence.
In trying this experiment, the body to be put in vacuo
must not have its condensed air coat burnt off. But the
same experiment should be tried with a body heated in
a hydrogen flame and cooled in hydrogen before being
placed in the tube, and the tube should be cleansed of
condensed air by having a hydrogen flame driven through
it. With these precautions it will be found impossible to
charge the body by influence because there is no electro-
lytic coating to the body.
From what we have learnt, influence is a vibration of
a3ther produced by the molecules on the surface of charged
bodies; and is due to the action of electricity on the mole-
cules : and the action that electricity forces on the molecules
of an insulated body may be called delayed electrolysis.
Also, it is plain that in every instance it is influence
that puts the strain on molecules to induce them to conduct.
That influence, in fact, is identical with electromotive
force. That the force is named influence while it sets up
a strain in an electrolyte, and electromotive force when it
has produced a current. There is only this difference,
that influence waves radiate in the surrounding aether,
and electromotive waves, having taken a definite direction
through the aether associated with molecules, retain that
direction.
11
INDUCTION
CHAPTER XXII
THE ACTION OF INDUCTION
INDUCTION is perhaps the most interesting part of our
study.
In the last chapters we examined the effect produced
by influence from a charge of electricity placed upon an
insulated conductor. Let us now examine the influence
or induction as it is called in the cases where it is set
up by currents in conducting wires. We shall find that it
has several particulars of detail which make it advisable
to separate it from influence, though the two are in reality
identical.
" If two wires are close together, one carrying a current,
an induced current is set up in the other/' When influence
acted on an insulated body, we found that a strain was
set up; here where the acted-on wire is not insulated
electrolytic action is produced, which sufficiently proves
that the strain in the case of influence was also electrolytic,
and that the charge that was produced by influence on
an uninsulated body must also have been electrolytic.
" Any change in the current of a wire, any pulsation,
causes instantly a similar pulsation in a neighbouring wire
not connected with it." This shows us that change of
strength in currents produces change of amplitude in the
influence waves.
" If the primary current is increasing the induced current
is opposite, if decreasing the secondary is in the same
direction."
This is very significant. No form of wave that we
16'2
INDUCTION 163
can think of could produce this double effect, but only
stationary waves, advancing with increasing power and
retracting with decreasing.
It is not by any means a general consensus, but opinion
appears to incline to the conclusion, that the aether waves
of induction circulate round the conducting wire in widen-
ing rings or spirals, and that with positive and negative
the directions of the circulation round the wire are opposite.
That the induction vibrations sent out from the wire,
and radiant equally in every direction, should by some
manner of interference set up stationary wave rings, does
not seem at all out of the way : but it is difficult to believe
that a current running along a wire can possibly make
those radiant vibrations move in circles round it. We will
therefore leave out this complication but adopt the idea
of rings. The rings, or rather cylinders, are superposed
at equal distances beyond one another, and when the
current increases they widen out, and when it decreases
they close in upon the conductor. If a picture were drawn
upon a plane in line with the wires, a series of waves would
be represented in the space between the two wires where
the plane intersected the successive rings: and though,
if they were spirals, this would not be correct as a whole,
it would correctly show what was actual at any direct
line between the wires.
Now if we suppose these rings of waves to separate more
from each other and from the conducting wire when the
current gets stronger, and to draw in towards this wire
when it becomes weaker, we see that they pass across the
other wire from two directions. Is this sufficient to
produce two directions in the induced currents on that
other wire ? ' The idea seems reasonable, but requires much
consideration and search for facts to confirm it.
We came to the conclusion that the only apparent reason
for the flow of electricity in any direction in a circuit was
164 INDUCTION
the position of the acid and basic molecules in relation to
one another. This being so, if the advancing waves of
induction act to induce these molecules to place themselves
in a certain position, and the retiring waves bring about
a reversal of the position, then we can understand the
reversal of the induced currents as well as their production.
This does not and must not be supposed to advocate
polarity, which is the idea that the solid crystalline mole-
cules in a piece of metal execute a somersault with each
change in the direction of a current, and which is an idea
not reasonably acceptable. The reversal that we refer to
occurs in the liquid air on the wire, and only amounts to
an inducement to molecular interchange in one direction
or the other as occasioned by the changes in the direction
of the aether wave forces acting upon the liquid, and
therefore easily movable, molecules.
" If two coils of wire be placed near and parallel to one
another, a momentary reverse current will be produced in
the one coil whenever a current is sent through the other:
or whenever the current is increased: or when the coils are
suddenly brought nearer while the current is running in
one of them. And a momentary direct current will be
produced in the uncharged coil whenever the coils are
suddenly separated: or when the current is diminished in
strength: or when it is broken oft'. So long as the coils
are kept still and the current steady in one of them, there
will be no induced current/' The same effects are produced
between parallel wires but not so strongly. All these
actions add confirmation to the idea that the induction
waves of aether form stationary circles round the wire.
When widening out, or when pushed nearer the acted-on
wire, their movement is one of advance towards it; and
the results are the same, a reverse current: when closing
in, or drawn away, their movement is a retiring, and the
result a direct current.
INDUCTION 165
The only difficulty is to explain why the wave remains
idle when not advancing or retiring, for " so long as there
is no change in the current, there is no effect from in-
duction/' The induction must be a continuous produc-
tion, for we cannot suppose that it is a mere temporary
movement set up by changing the position of a wire, or
increasing or decreasing the current in it: the induction
waves must be there always while a current is passing on
the wire, and the only reason for their not acting like
ordinary waves must be that they are these extraordinary
stationary waves, and that they are of such dimensions
that the inactive wire may remain in the hollow of a wave,
and that its molecules may remain unaffected so far as to
produce a current, or if they did produce any different
action in the molecules on the wire, it could only be on
those at opposite sides of it, which could only produce a
current across the wire and not along it. But if the current
in the influencing wire is started, or increased, or decreased,
or stopped, although the charge may pass along it with
the speed of light, it begins and acts on one end of the wire
before it arrives to act on the other end, and the induction
waves would not be all drawn across the responding wire
at the same moment, but would cross it in succession and,
as it were, obliquely from one end to the other, and so
cause an electrolytic action to run along that wire.
With a strong current in the influencing wire, the in-
duced action is so strong, when the primary current is
broken, that a sharp shock or discharge is produced in the
influenced wire: but it is only very strong currents that
can do this, because induction is really a very weak force.
" A variable current produces self-induction in the
primary wire; opposing if increasing and augmenting if
decreasing. To set a current in motion reaction must be
overcome, once in motion it continues of itself. Self-
induction is a sort of inertia/' This idea of inertia is
166 INDUCTION
borne out by the fact that in a vacuum tube many of the
oxygen molecules continue their course regardless of the
position of the anode if it does not face the kathode: and
we have seen the same thing occur in air when two wires
joined to complete a circuit were crossed near their ends,
and the oxygen propelled beyond the crossing combined
with and heated one of the ends : and we have the same
action in a Ley den jar, or an oscillator, where the oscilla-
tion of the spark is due to the alternate surging surcharges
of the moving molecules of the condensed air coats.
Wherever we have motion and material we must have
inertia. In a coil of wire, each turn has . an inductive
action on every other turn in the coil, and the effect is
magnified according to the number of turns, and the result
in a coil with many turns is so forcible that it has been
found that this self-induction must be taken into account
in electromagnetic machinery.
" When the electric circuit is broken, the current con-
tinues to flow across the break for a short time, producing
an electric spark, and the intensity of this spark is a rough
indication of the amount of kinetic energy possessed by
the current/'
Inertia is the only inherent property resembling force
that is possessed by material, and if the inertia is that
due to received motion, the material expends the inertia
in reproducing the motion in some form. The motion of
the electric aether wave has no inertia, being immaterial,
and its motion when given to material is reproduced by
the material as electric, or heat, or light, or actinic vibra-
tions, all of which are found in the spark: and it is the
inertia of the electrolytically moving material that bridges
the gap and reproduces the vibrations.
This kinetic energy depends on the amount of surface
brought into action by the current. In a short loop there
is only enough to produce a small spark, but if the circuit
INDUCTION 167
is made into a coil round a bundle of iron wires, " a spark
several inches in length may be produced by suddenly
breaking the circuit/' It is due to the collective inertia
of the molecules of the air skin on the wire, which have
been moving electrolytically, and which convey their
electrolytic motion to the intervening air of the
gap-
Some scientists say that " the energy of the waves is
stored in the medium/' This is a reversion to an old idea
that has been found untenable, as in the case of latent
heat. There has not seemed to be any need or possibility
of storing either induction, or self-induction waves, and
very much reason for deciding that the medium, meaning
by that term the material gases, or other substances,
surrounding the wires, is not used in any way by the
induction waves. The energy of induction waves does
not spread beyond a few feet from the exciting wire,
because their force decreases quickly with distance and is
but feeble to begin with, and may possibly be all used up
by the impurities in air: and no instances of air storing
can be cited, nor does it seem reasonable to suppose that
sether ever does any storing.
When both wires carry currents there is a double effect.
" Electric currents that flow in the same direction attract
each other: in opposite repel/' Or as another author
says: "Wires attract each other if the currents in them
are going in the same direction: repel if opposite/' It is
convenient to speak of wires or currents attracting or
repelling each other, but we must clearly understand that
there is no such thing as attraction or repulsion of wires
or currents. The induction vibrations produce some
movement of the molecules of the air skins on the wires,
and this causes an equal and opposite movement of the
wire to which the moving molecules are attached: the wire
appears to be attracted or repelled, but in reality is pushed
168 INDUCTION
towards, or pushed away from, the other wire by the
molecules on its own surface.
Induction vibrations produced by currents running the
same way produce identical movements in the molecules
on both wires. The currents, we will say, are moving from
left to right, and the induction waves therefore expand
from left to right, and their action would be to hasten the
current and to cause the molecules to move diagonally
towards the further sides of the wires, which would push
the wires together. With counter currents the induced
action of the molecules would arrest the molecular current
motion, thus producing accumulation on the near sides of
the wires which would push them apart. It is not the
induction waves that do this pushing, but the molecular
action induced by the waves. Induction waves are aether
waves and have neither attraction nor repulsion such as
waves of substantial material have, but they cause indirect
actions of this sort.
" Similarly electrified stationary particles repel, but
similarly electrified currents attract, therefore similarly
electrified moving particles should attract." Maxwell's
theory is, " that with their velocities equal to light, the
electrostatic repulsion of electrified particles will just
balance their electromagnetic attraction."
The movement of material with the speed of light is a
fallacious idea. The movement of the current on copper
wires has been found to be twenty-four thousand feet in
a second, and that of the material molecules infinitely
small.
Still, you might say, that if the vibrations pass with
this speed, and if molecules acted on by waves of that
velocity attract: and if when acted on by waves of double
the velocity as they would be with contrary currents
they repel; then the whole question is answered.
But how ? It is no answer to a question to repeat the
INDUCTION 169
words that prompted the question, though the trick is
common enough. What is electricity ? you ask. Elec-
tricity, you are told, is a property of electrons. What is
life ? A property of animated matter. What is shoe-
leather ? A leather they make shoes of. Such shallower
than ditchwater answers are often accounted as splendid
discoveries, but they do not satisfy all even ordinary
inquirers. If we ask why currents running with great
speed attract one another, and why when running with
double that speed they repel, it is no answer to say, because
of their speed. And besides this, one cannot conceive
why the speed, whether it be a snail's pace or a lightning's
pace, can have anything to do with the business : and what
we really want to know is, why do currents running in the
same direction cause attraction, and in the contrary
direction repulsion or rather, why are the carrying wires
variously pushed by the actions caused by the currents ?
The current running along the wires cannot push them
sideways: nor can the vibrations of aether, or the sether
itself, in the space between the wires, push or pull them:
the whole effect of the induction wave is to set up molecular
action in the air skin on the wires, and it must be the
effect of this action alone that gives movement to the
wires.
" Two circles of wire in which flow like currents turn
their planes parallel to one another in the endeavour to
embrace the greatest number of lines of induction, and are
attracted. They act like magnets. With opposite currents
they repel that is endeavour to turn round so as to be in
accord and embrace the lines/' But it is no action of the
aether waves, as waves, that moves the one wire into
agreement with the other: nor are there such things as
lines of force in sether, sweetly simple of conception and
saving of trouble as such things would be.
If we place one of the wire circles so turned towards a
170 INDUCTION
second circle that it is at right angles to it like the down-
stroke of a T, then the current in one part of this first
circle is towards, and in another part away from the second
circle. Now it is reasonable to suppose that the induction
waves from the second circle should act differently on
these approaching and retiring currents of the first circle:
that in meeting or overtaking the currents they should
oppose or assist the currents: and that the effect of the
meeting wave should push aw r ay the part of the wire
carrying the advancing current, and the effect of the over-
taking wave should pull away the part carrying the re-
treating current, and the double action being in one
direction, the near side of the sideways circle would be
moved away until it came to be at the same distance
from the second circle as the other side, after which only
ordinary induction by parallel currents would act.
" Conductor circuits in which currents are flowing, turn
so as to coincide in direction of current. But a single
conductor, if movable, when excited turns east and west/'
The single circuit turns east and west to place itself parallel
to the electric current produced on the earth by the heat
of the sun, and which circulates with the sun. It is a
thermo-electric current quite similar to those that we have
studied in our examination of thermoelectric action.
INDUCTION
CHAPTER XXIII
THE PRODUCTION OF INDUCTION
THE action that produces induction is the electrolytic
movement of the molecules of the condensed air upon the
surface of the producing wire, and this sends out aether
waves of induction which seem to be different from the
waves of influence. Those influence waves acted con-
tinually without pause or change, and any movement of
the bodies employed only intensified or lessened the
influence according to the decrease or increase of the
distance between them. These induction waves are dis-
continuous, and only act in response to movements that
have nothing to do with electricity, or in response to
increase or decrease of current, and in both cases only
during the time spent in these actions.
Influence produces an electromotive force on the in-
fluenced body, and a strain against the force. Induction
produces a much stronger action, a current generally, even
on an insulated body: that is an electromotive force and
an electrolytic movement of the molecules of the con-
densed air on the responding wire. Influence waves acted
as ordinary waves would do, radiating from the point of
origin and passing away into space without return. The
induction wave acts in such a way as can only be explained
by supposing them to be those peculiar combinations of
vibrations that are called stationary waves.
What then are stationary waves ? If you throw two
stones into a pond, they will make circular waves that
171
172 INDUCTION
spread out from the points struck by the stones, and where
the circles meet there will be formed stationary waves:
you can see the circular waves pass into and reappear
beyond these stationary waves, but these latter keep their
position. -You walk beside a brook and see the water-
strike against the posts of a fence pushed into the stream
from both sides, and from where it strikes the posts there
are two series of ripples sent out into the stream and
spread like the feathers of a bird's open wing, and where
these ripples meet you see a strong stationary chequer of
small waves that is not carried down by the stream. You
try your hand at tuning your piano a stupid thing to do
unless you are a practical musician and you make a
discord between two notes, and produce a series of semi-
stationary beats. And Newton's rings are stationary
waves of interference of light waves.
What is it that in each of these cases causes the station-
ary wave ? Interference. The waves in the water are
stationary because the waves from the points of origin
interfere. The waves of sound are not of the same length
and through interference make beats. And we know that
there can be interference in aether waves of light. What
then does this point to in induction except interfering
vibrations between the two wires ?
The striae seen in some of Geissler's tubes are no doubt
beautiful examples of stationary electric aether waves.
The current can do little by conduction in the rarefied
gases, but the mutual induction vibrations are conveyed
by the aether between the nodes, and these aether waves,
positive and negative, being of unequal length, on meeting
interfere and form stationary waves of augmentation and
cancellation: and in the augmentation they act on the
small quantity of gases remaining, and by encouraging
the combination of the gaseous molecules they produce
light and heat: in the cancellation bands no such increase
INDUCTION 173
of action occurs as the effects produced by the vibrations
cancel one another.
The induction interference aether wave in air is probably
much smaller than those in the tubes, but it appears wide
enough to allow of a wire to rest in the cancellation part
unacted upon: and the wire would be driven to that part
by the action of either of the augmentation parts on either
side of it.
Interference then must produce the stationary waves
of induction. In Geissler's tubes they are produced
because the negative influence wave is longer than the
positive: the distance between two striae showing the
space in which the one series has differed one beat from
the other. In what way can we account for the same effect
in influence from the current on a wire ? In the tube the
positive and negative influences were separated, one at
each end of the tube, and met: but an equal effect would
have been produced had they both started from one node
and gone in the same direction: and this is what occurs
on the excited wire. Both currents, positive and negative,
pass on the excited wire, and both send out, on the sur-
rounding sether, series of waves, which, being different in
length, interfere and produce stationary waves. There
could of course be none of this interference with influence
vibrations because they are produced by positive or
negative charges acting alone: and this is probably the
only difference between influence and induction.
There is nothing to support an aerial wave theory.
And there is another point that we may say that we have
arrived at, and that is, that the idea that " electric lines
of force are produced by induction " is a delusion utterly
incompetent to explain the effects produced by advance
or retreat of wires, or even of increase or decrease of
current: and that aether rods, induction lines, and tubes
of force, are mere fanciful examples of obscurum per ob-
174 INDUCTION
scurius delusions and snares. Influence and induction,
though they form the basis of electromagnetism which is
occupying so much scientific attention at present, have
not had the thorough investigation that they deserve, and
no attempt has been made to examine their origin, or
explain their action, except by these mythical polar forces,
rods of force, and such-like extravagances. As one writer
puts it, " Men are now more interested in the pecuniary
gain that new scientific inventions may bring, than in the
science of the inventions " : and they have invented for
the furtherance of their object a very elaborate nomen-
clature and method of measurement which includes quite
puzzling mathematical formulae interwoven with ohms,
and farads, and other mystic terms, without which, as a
shibboleth, the uninitiated are accounted but philosophic
Midianites, and unworthy of scientific existence. Modern
books are crammed with mathematical formulae, but they
are not worth much as they will prove anything one
chooses to put into them.
But with this mechanical, or with the commercial side of
the question we have no desire to meddle : our aim is the elu-
cidation of those points that have been neglected, and is a
mere search for knowledge and not a yearning for lucre.
Judging from what is published, it strikes one that the
mathematical forms employed by the invention seekers
are not always based on correct theories, as the following
will show.
Electric influence = inductive power, and "its effect in
dry air is taken as the standard of comparison at 1. Gases
have nearly the same power as air. The property varies
according to the substance and to the time it has been in
use: it increases in the case of glass to nearly double,
between instantaneous application and a minute's con-
tinuance of current. It is plain that the substance acts
in conveying the influence, and that some substances
INDUCTION 175
allow influence to act through them better than others.
Sulphur, an elemental substance, acts two and a half times
as well as air which is a mixture of elemental substances,
and gutta-percha, a compound, acts as well as sulphur:
glass, also a compound, acts three or four times as well as
air. Oil is a better insulator than air: but the influence
through it is greater than through air. Air and glass are
better nonconductors than ebonite or paraffin; but in-
fluence acts more strongly across glass than across ebonite
or paraffin, and across these more strongly than air/'
Here is a nice set of riddles set up through misunderstanding.
One would think after reading the above that there must
be some inductive capacity in material, and there is nothing
of the sort : this supposititious quality is merely a muddle
of induction, conduction, and electric action in the con-
densed air on solids.
An entirely wrong point of view has been taken up for
considering the " inductive action " imagined in the above.
It is not material to our inquiry and we might pass it
over and leave it to its believers, were it not that the
investigation of it may help us to find out what we want
to know, and we must omit no point that shows any chance
of benefit.
If we consider the items given in the above quotation,
we see that the better nonconductor a substance is, the
better it conducts the influence through it: or to put it
in another way; the more resistant the substance is to
electrolytic action, the less it can be acted on by the aether
vibrations of influence: and the less a substance acts by
reason of the influence vibrations, the less it obstructs
them and the better they pass through. A metal plate
entirely obstructs influence because its condensed air
coating absorbs the vibrations and becomes electrolytically
active, and continues to absorb because the electricity
produced is conducted away as fast as it is induced. A
176 INDUCTION
plate of glass also has its liquid air covering influenced,
but, as there is no conduction, the coat can only absorb
the vibrations until it is saturated, and then the aether
vibrations pursue their course without any more obstruc-
tion, and this is why glass seems to increase in conduction
of induction by use.
When it is said that one substance conveys influence
better than another, it conveys to us quite the opposite
impression to what really should be given to us by the
correct description of what happens; for the reality is
that the one substance acts less than the other, and thus
allows the influence waves to pass through it with less
hindrance. There is no conduction of influence: the
substances do no conveying of the vibrations which are
dependent on the aether alone: if a substance acts it is
to absorb flie influence waves, and it is only when it cannot
act that the waves pass through unobstructed, unabsorbed
and unconveyed by the material.
Some substances have been found to obstruct the
influence vibrations two, three, or four times less than
air, and this appears to us at first sight to be a great
difference, and assumes an aspect of importance till we
consider that air acts several million times less than copper,
when we become reassured, and can willingly admit that
the vibrations may have some very slight action on the
air and on these other materials that may ordinarily chance
to come between the inciting and receiving conductors,
but the action is so slight that its counteracting conduction
effect on the conductors is utterly inappreciable. If clean
air has any action at all it is due probably to the carbonic
acid gas in it.
'The energy of self -induction = coefficient of indue -
C 2
tion x current squared -f- two : or 2~ m : and it is supposed
to be stored in the medium round the conductor. Change
INDUCTION 177
in the value of current produces change in amount of this
energy." The latter part of this quotation we can accept
as palpably true, but not the idea of storage. We have
seen that the air is scarcely or perhaps not at all acted on
by induction, and there is no method resembling electric
storage, that we know of, except chemical action or some-
thing equivalent, and which reacts strongly, often violently,
and always unmistakably ; the storing therefore cannot
be in the air. The aether does no storage, and there is
no other medium but the condensed air on the wires: this
is the substance in which on the acting wire a current runs
that originates the induction, and 011 the receiving wire
in which the influence works to produce a current, so there
is no possibility of storage in either of these. We may
therefore safely reject the idea of storage of induction.
We will now gather together our facts and see what we
have to go upon. A current in a wire produces induction.
Induction is a vibration of aether produced by electrolysis.
It reproduces electrolysis on other wire circuits. Not
acting continuously but accompanying transverse move-
ment of conductors and change of current. Acting on a
length of wire directed towards its source, but not on a
breadth when not moving. Stationary waves are some
width apart. Interference produces stationary waves,
and when a current passes on a wire there is a cause for
interference in the induction waves sent out. We have
seen what we believe to be actual cases of stationary
induction waves, and all other wave motions produce
stationary waves where there is interference. There are
no connecting lines or rods to push or pull conductors.
With these for a basis we can only come to these con-
clusions, which are, that the electric action on the excited
wire sends out two sets of radiant aether vibrations which
by interference set up stationary aether waves which are
broader than the conducting wires, and that when the
12
178 INDUCTION
wires are not acted on it is because they are driven to that
part of the wave where the effects of the vibrations cancel.
And second that the electrolytic motion of the molecules
set up by the induction on the responding wire, pushes
that wire towards or away from the excited wire, and that
the movement is not one of attraction or repulsion as
commonly understood though it resembles what is meant
by those terms. And we might add a third conclusion,
which is that there is no such thing as attraction or repul-
sion as commonly understood, either in electricity,
magnetism, or gravitation.
There is another point to be noticed. Two vibrating
forces meeting pass one another unchanged: any inter-
ference that occurs is between the material waves that
they have produced: when the forces emerge from the
interference area, we can see that they produce again
waves similar to those before the interference, only becom-
ing weaker as they extend through loss of energy of the
force. It is convenient to talk of vibrations acting on
one another, but a vibration cannot be cancelled or changed
or reinforced by a different vibration and only their effects
on material may cancel, or change, or reinforce. Let us
remember this.
STORAGE
CHAPTER XXIV
ELECTROLYSIS NOT STORAGE
ELECTRIC motor carriages for use on ordinary roads are
supplied with electric power to drive them by " stored
accumulators " carried on the car. The weight of these
accumulators is a chief objection to the use of electric
cars: but this will probably be rectified as there seems to
be no apparent objection to the use of aluminium and a
light chemical instead of lead as at present.
Such terms as storage and accumulator give one the
idea that electricity can be collected and kept in receptacles
from which it can be drawn off like water through the tap
of a cistern. There is no electricity however in an accumu-
lator. Accumulators are merely a sort of voltaic batteries,
in which the metal used for both anode and kathode is
lead. When they were first thought of they were made
of solid lead plates, and they were brought to act as bat-
teries by having a strong current passed through them
for some time, and for several times reversed, until the
surfaces of the plates, by the action of the acid in which
they were dipped, were brought to a highly sensitive
chemical condition. They are now more effectively and
cheaply made. Two sets of perforated lead plates have
their perforations filled with a paste made of red lead
and dilute sulphuric acid: and they are arranged in an
acid bath, so that the plates of one set alternate between
those of the other set, but not touching : each set is joined
up by a cross bar, and from these are wires to conduct
the electricity to the driving machinery of the car. Either
179
180 STORAGE
set of plates may be taken as positive or negative to begin
with: and according to the direction of the current sent
through the apparatus to prepare it, the current reduces
the paste on one plate and peroxidizes that on the other.
When the accumulator is used, the conducting wires
are attached to the motor, and the reverse chemical action
that is set up in the accumulator produces a current which
continues with diminishing effect until the plates are
.brought to an equal condition, when they become inactive.
; ' The accumulator current is of shorter duration than
the charging current, but at the beginning of greater
intensity." This we can quite understand and it would
be a great improvement to the apparatus if by some device
the chemical action and the current it produces could be
regulated.
It will be seen from this description of the accumulator
and its preparation for work, that there is no storage in it
of electricity, but merely that chemical changes -are pro-
duced by the electric charging, which, when they are
allowed to react, cause a strong electrolytic action between
the plates and consequently a strong current of electricity.
The charging current is used, not because it leaves any of
its charge in the cell, but because it prepares the plates
better than can at present be done by hand. All the
energy of the charging current is changed to work to
perform this preparation, and the prepared accumulator
w r orks entirely by its own chemical action.
The nearest approach to storage of electricity is when a
condenser or Leyden jar is charged. It really seems as
if we had poured the charge into the jar and that it cannot
get out again unless we give it a channel for escape. The
outside, which must be in connection with the earth if
we wish to give a strong charge, is charged oppositely as
strongly as the inside, and the two charges hold one another
by "mutual influence. The surfaces bind each other's
STORAGE 181
electricities so strongly that there is no free electricity
inside or outside; and if the plates of a condenser are
separated they are found to be charged over both their
surfaces and very much more strongly than they could
have been without the aid of their mutual influence.
Now influence is produced by electrolytic movement.
So we must conclude that this mutual influence between
the charges on the two surfaces is caused by electrolytic
movements in the liquid air coatings on the surfaces of the
nonconductor intervening between the plates of the con-
denser, or, in the case of the Leyden jar, on the surfaces
of the glass of the jar: and that the effect of the charging
has merely been to put the molecules of the liquid air in
electrolytic motion, or at any rate, to give them a tendency
to such motion, and that the action is very similar to that
in the motor-car accumulator. We will consider this
more carefully further 011, and will now examine some cases
of apparent storage.
One of the great obstacles to fast signalling through
submarine cables is that they act as condensers. Various
expedients have been tried to better the condition, such
as throwing an opposite charge into the cable with each
signal to cancel the induction, or using very delicate
instruments with a very light charge so as to produce as
little induction as possible, but none of them has done
more than slightly lessen the condition. What happens
is, that a quantity of electricity is wasted in putting the
inner surface of the rubber sheathing of the wire into an
electrolytic positive condition, and helping it to put the
outer water skin into an equal condition negatively, and
in keeping up these two conditions. Perhaps enclosing
the wire loose in a tube, so as to be surrounded with air,
would cure it. Manufactured as the cable is, the wire has
but a very small coating of liquid air, and the current has
to force much of its way by electrolysis of the rubber?
182 STORAGE
which is several times more resistant than gaseous air
and probably many thousand times more so than liquid
air: so, even supposing this last to be over-estimated, the
facility of carriage would be decidedly in favour of an air
surrounded wire.
All condensers on being discharged by sparking between
knobs at the ends of short, stout wires tend to overdo
the work and to send a surplus to the opposite plate : this
surplus is at once returned, with some small loss, as a
reverse spark, and an oscillation of sparks goes on till
equilibrium is established. The charge on the condenser,
either sets the molecules of the condensed air coating in
electrolytic motion, or it gives them a tendency to move
in certain directions: whichever is the case, when the
spark discharge takes place the molecules by relief are
enabled to spring back towards the position of rest, and
their unchecked impetus in doing so causes them to over-
shoot the mark and to move or incline beyond the position
of stability, and in this way to leave themselves in a feebler
condition than the molecules of the other plate which
now have an excess of motion or strain, and in turn get
rid of it by a discharge which is more forceful than neces-
sary, and thus the oscillation of the molecules in decreasing
amplitude in the two plates produce to-and-fro sparks
till the plates have come to equal charges. This must
be the manner of the oscillation, for by no possibility can
an aether vibration be made to oscillate backwards and
forwards, but a molecule or any other lump of attached
material can be made to do so.
The above is the orthodox way of explaining the pro-
duction of oscillating sparks, and it leads us to suppose
that the molecules of an insulated surface are not merely
under a strain when they are electrified, but that they are
actually in slow motion, and the following are some facts
which confirm that idea.
STORAGE 183
" Increase of the capacity of the condenser decreases
the speed of the oscillation." With mere relief of strain,
increase of area should make no difference, but with move-
ment over a space we might expect a retardation when
there was more ground to cover, and that it would cause
a damping off of the more remote movement, the inertia
of the molecules nearer the conductor influencing those
further away, in the same manner that the prevention of
oscillation by a wet thread or other damping conductor
must be due to the obstruction in the conductor which
reacts on the action of the molecules on the condenser.
However carefully conductors, condensers, jars, and such-
like things may be insulated, they lose their charges after
a time, and the loss is greater at first and gradually lessens.
Now the condensed air coating on a body is " electrified "
by absorbing influence sether vibrations which produce
some change in the molecules, and this change wears away
as the liquid air molecules recover their previous condition,
and in recovery they produce sether waves similar to those
that they received: but to be able to do this the molecules
must have electrolytic movement.
It might seem as though we were getting away from
the subject of storage, which in truth we are in a way;
for what these examples are leading us to, is, that there
is no storage of electricity at all, but merely an electro-
chemical change produced by electricity, which in recovery,
as exemplified by the materials in the accumulator, pro-
duces electricity which is entirely new. In fact that the
motion that we call electricity when it has produced an
effect ceases to be electricity or anything else, and any
result from the effect, whether electric or otherwise, is a
new production. One cannot bottle up a motion, nor is
any of it left after it has been expended on work.
Air is often said to be stored with electricity, but it is
not the air that is charged but the dust in it. The earth
184 STORAGE
is constantly producing electricity, most of which, owing
to want of arrangement for separating the positive and
negative, is at once cancelled. It is the damper and more
active parts of the earth's surface that act as the anode
in the system of production, and the drier and less active
parts as kathode, and if the drier parts can be raised by
the winds as dust before losing their positive charge, the
equal negative charge is left on the earth uncancelled.
In time the two electricities of the earth and air cancel 1
one another by a lightning flash.
Flame is also said to occasion the storage of electricity.
If we put the end of a conducting wire from a charged
body into a flame, the body is discharged. The body,
instead of getting rid of its electricity in the usual slow way
by influence, finds an easier way and takes advantage of it .
This means, according to the theories of the moment
and there are several that the molecules of the gases of
the flame carry away with them each a small store of
electricity, either as a coating, or as an electron, or in some
other way. The gases are in an active state of chemical
change and are ready to accept any sort of vibrations
offered to them, so they absorb the vibrations conveyed
along the wire from the body: but the molecules in the
flame are in too active a condition to receive them as
slow electrical vibrations and take them to help the quicker
vibrations of heat. There is no carrying away and no
storage.
After a Ley den jar has been discharged, a residual
charge remains in it, and the discharge of this can be
hastened by tapping.
The amount remaining depends on the length of time
the jar has been charged, and the sort of glass it is made
of. " The residual charge is supposed by Maxwell to be
d\ie to heterogeneous substances having unequal con-
ducting powers or the molecules are subject to a strain
STORAGE 185
from Avhich they do not at once recover/' The first of
these ideas does not appeal much to us: every electrolyte
is made up of materials having unequal powers of con-
duction, but never is there any residue of electricity left
in an electrolyte. The electricity in the case of the Ley den
jar is on the two surfaces of the glass and is straining the
glass in the endeavour to change it into an electrolyte to
conduct the current: and on this account it is that time
and the sort of glass count. But besides this there is a
layer of some nonconducting substance between the foil
and the glass which has been used for sticking the foil to
the glass: and there are probably small patches where the
glass is unconnected with the foil which patches would
be charged by induction, and lose their charge by induction :
and what effect the nonconducting material might have
it is difficult to say but this instance has not been brought
forward as a proof of any fact or theory, as to show how
careful we must be in experimenting and in interpreting
our experiments.
The longer the jar is kept charged, the stronger is the
residual charge, and the longer it lasts, because the glass
takes on more strain and takes longer to recover.
Thickness makes no difference in the time of recovery,
as the relief does not soak in from the surface but is simul-
taneous everywhere regardless of depth.
The amount of strain that can be produced by charging
increases with the temperature, and the relief of strain is
also assisted by heat, but in both cases only up to a certain
limit above which the molecules become set in a new
arrangement and there is no return. At 250 C. for soda
glass the whole of the strain vanishes.
When the heat of a compound under strain is increased
to the liquidity of the substance, conduction by electrolysis
begins, proving that this sort of strain is incomplete
electrolysis.
186 STORAGE
Now in the whole of this we can find no reason for sup-
posing that there has been any storing of electricity in the
glass, but merely that the electromotive force, or influence
as it is named in these cases, has been used up in making
and maintaining a strain in the glass, and that the glass
molecules have reproduced a similar force in recovery
from the strain, just in the same way as was done by the
material in the accumulators, except that in their case
there was complete action both in charging and in recovery,
and in this case of the glass merely recovery from incom-
plete action.
There is no storage in a solid body charged with elec-
tricity, but merely a pseudo-chemical change in the mole-
cules of its liquid air coating. These recover their former
state either slowly by discharge of influence vibrations, or
quickly by discharge of electromotive force. The charging
force produces a condition: reversion from the condition
produces an equivalent amount of force : but this is a new
force and not the old one that was expended in work.
It is convenient to use such expressions as " charging
with electricity/' but there is no storing in any case but
only a production of chemical or pseudo-chemical change:
there is a movement towards electrolysis.
CONVECTION
CHAPTER XXV
CONVECTION AN INTERRUPTED CONDUCTION
WE have not considered convection as a separate pheno-
menon in these chapters, but seem to have accepted it as
most people do, as a self -sufficing fact : believing that any
piece of material that happens to come into touch with an
electrified body receives some of its electricity and carries
it away with it. This is so plainly true that nobody
seems to have thought that it wants any explanation or
to have cared to know more than that it is so.
There were some small experiments which were shown
us on our first introduction to electricity, which you will
find at the beginning of most books which teach the sub-
ject, and by which we were supposed to learn what elec-
tricity is. No explanation was given of them beyond
saying that the reason why some small thing was attracted
and repelled from a charged body was, because the body
that did these things was electrified, and that the small
thing acted on was carrying away some of the electricity
of the charged body. Teacher and students all seemed
satisfied, and if questions have ever been asked, no one
apparently has cared to record them, or their answers, or
probably to know whether there were any answers at all,
but to have taken the results as sufficient explanation.
We however want to know the why of the whole business.
If a stick of sealing-wax is rubbed with a bit of fur, each
of them, the wax and the fur, will be found to have acquired
some property that they had not before, and this property
we know as electricity, and that it is produced on the wax
- 187
188 CONVECTION
and fur in the same manner as it is produced in the electrical
machine, that is, by electrochemical action in the con-
densed air coating of one or other, or of both substances,
and that if we test them we find that the wax is negatively
and the fur positively electrified.
If now an elder pith ball (which acts better if it is gilded)
or a small feather, hung by a silk thread, is put between
the sealing-wax and fur, it will fly backwards and forwards
between the two and continue to do so till their electricity
is exhausted. The ball or feather is convecting. It flies,
say, to the wax, receives from it a small charge of its nega-
tive electricity, carries this to the fur and with it cancels
some of the fur's positive electricity, gets from the fur a
small positive charge which it carries to the wax, and so
continues to act till all the electricity in the wax and fur
is cancelled, and they have become ordinary unelectrified
bodies.
In a future chapter we will go more fully into the reasons
for the attraction and repulsion which we see acting on
the small objects, but just now we will inquire more
particularly how the convecting of the electricity that these
little bodies transfer is done. We will however first try
a few more of these simple experiments.
If after rubbing the two together, the wax alone, or the
fur alone, is brought near the pith ball, the ball will fly
to meet it, cling to it for a moment, and then fly away
and constantly afterwards avoid its approach. Here the
ball has been attracted, has received a small charge of
electricity, and because this charge is of the same sort as
that on the charging body, the ball is repelled. Evidently
the ball has suffered a change in some way, for the excited
body first attracted it and since contact now repels it.
If, instead of the wax, a warm, dry flint glass rod be
rubbed with a silk handkerchief and brought near the
suspended pith ball, it will fly to the rod, leave it, and
CONVECTION 189
elude its approach just in the same manner as it did the
excited wax after touching it : and it will oscillate between
the glass and silk in the same way as it did between the
wax and fur. Evidently the sort of electricity used to
act on the pith ball makes no difference in its actions.
Now if a glass rod excited by rubbing with silk, and a
sealing-wax rod excited by rubbing with fur, are placed
near and on opposite sides of the pith ball, it will oscillate
between them till their excitation is lost: and the same
will happen if the silk and fur are used instead of the glass
and wax. There can be no doubt therefore that the ball
carries small charges between the excited bodies, and that
the charges are alternately of positive and negative elec-
tricities.
If either the excited glass rod or excited wax be brought
near two pith balls which are suspended on different silk
threads but touching one another, they will both fly to
the excited body, leave it, and separate from one another,
and will afterwards elude both the rod and each other.
If the hand or any other earth-connected and conducting
object be brought near the pith balls, they will fly to it
and drop away uncharged, for it is only through insulation
that they retain any charge.
If the two balls are suspended so as to hang a couple of
inches apart, and they are approached by the positively
excited glass on one side, and the negatively excited wax
on the other, they will fly outwards one to the glass and
one to the wax, then fly together, then return to the rods;
and so continue till the excitement of the rods is gone.
And if the rods, used as in the last experiment, are
instantly taken away on the balls touching them, the two
balls will fly together, cling for a moment, and then fall
apart quite indifferent to one another, all electricity having
left them.
If conduction with the earth were allowed by using a
190 CONVECTION
fine wire, instead of the silk thread, for their suspension,
the electricity would escape instantly because the balls
would then form part of a conductor. From this and the
other experiments we may safely conclude that the material
of which the balls are made has no significance so long as
it is a material that conducts, and therefore that the action
of the charges that they receive is confined to the con-
densed air on their surfaces as we have found to be the
case in all the investigations that we have made hitherto.
It would appear then that the electrified body transfers
a sort of strain to the molecules of the condensed air
coatings on the balls or other small bodies, and that this
strain is either positive or negative according to the elec-
tricity of the charging bodies, and that it is cancelled by
the addition of an equal portion of the opposite strain.
That if the positive strain is a surplus of electricity, it is
not merely the addition of an inactive fluid to the surface
coatings of the bodies, but an active motion, or incentive
to motion, or as we call it a strain: and that the negative
charge also produces a strain: and that both of these act
so as to cause a particular motion on the bodies such as
will produce influence vibrations in the aether between
the bodies, which vibrations so act on the molecules of
the condensed air coatings that the excited molecules push
the bodies together or push them apart, the motion of the
aether being converted to motion of the molecules.
The old statement that similar electricities repelled and
dissimilar electricities attracted through space because they
were electric, belongs to the unmeaning explanations of
old myths. No counteraction can occur between separated
bodies unless motion is carried by material through the
intervening space, including in this term the material
aether: there is no such thing as action at a distance.
The charges on the bodies, if they are not allowed to
touch, gradually disappear because they produce that
CONVECTION 191
motion in the surrounding aether that is called influence.
If the strain did not produce a certain amount of motion
of the molecules coating the charged body, that is, if it
remained an inelastic resistance and nothing more, it could
not produce any motion in the aether. We must conclude
therefore from this and other instances that the strain
produces some motion of the molecules.
Part of the influence motion of the one body acts on the
other, and produces a new movement of the molecules of
the air coat, and that movement causes the body to move
one way or the other. The direction of the movement of
the body depends on what sort of electricity sent out the
influence waves, but beyond this electricity has nothing
to do with the action, but only the mechanical movement
of material on the body moved.
If a pointed wire is added to the conductor of an electrical
machine, the electricity produces a wind in the direction
of the point of the wire. Now if we stir up the dust of the
room with a broom, and arrange the wire so that its point
is illuminated by a ray of light that makes the dust motes
visible, they will be seen going leisurely towards the wire
and then darting away from it. They go to it unelectrified,
receive a charge, and dart away repelled, the repulsion
being much aided by the electric wind. They are con-
vecting. The molecules of condensed air on the surfaces
of these dust particles have received an electrical impulse
from the molecules on the wire. Had the dust particles
been arranged in a continuous string, they would have
formed a conductor, and the impulse would have sped
away : as it is, the motes being insulated bodies the impulse
remains on each as a strain.
The strain is an impulse to electrolysis received by the
condensed air molecules, which can get no further than
the limits of the insulated convecting body, and we may
therefore call convection an interrupted conduction: an
192 CONVECTION
incipient electrolysis which is produced by any charge,
positive or negative.
The convecting body must be a compound body in which
electrolysis can act: no elementary body can convey
electricity. When a ball of elementary metal conveys, it
is not the metal that is doing the work, but the condensed
air on it, or the product of some chemical action that is
going on, on its surface. It is the same with dust; and
moisture, if it conveys, does so because it acts electro-
lytically. Clean air, such as we commonly call dry,
neither conducts nor convects, because the moisture in it
is in the form of molecules, which, though they are com-
pound, cannot move their components electrolyticall}-
but in damp air the moisture is in minute water drops,
in which drops electrolysis can act as easily as in a bucket
full: and the only cause for doubt about electrolytic con-
vection by the water in air is that an ordinary charged
body would probably not have enough force to overcome
the resistance of water to electrolysis.
What we have now learnt is that convection is the trans-
fer of an electrolytic strain; and that the convecting body
is driven away from the charging body by influence
vibrations.
In performing the little experiments mentioned in this
chapter, it is advisable not to handle the fur or silk too
freely, or their charges will be conducted away. To
prevent this tie them to glass rods or pieces of dry stick.
ELECTRICITY
CHAPTER XXVI
ELECTRICITY CAUSES A MOTION OF MATERIAL
WE have now studied the production and action of elec-
tricity in many ways and should be ready to answer the
question. What is electricity ?
Our usual practice has been to collect data and to deduce
our statement from them, but we have already done this
and studied electricity from every point with all the data
available, so now we will assemble our deductions, recalling
the principal facts, and on these deductions will base a con-
clusive judgment.
One deduction that will be found as the last word in our
study of every separate subject is, that electricity depended
on electrolysis, and that being so, electrolysis should ex-
plain what electricity is, therefore we will closely examine
its action.
To prevent any mistake as to the meaning of the terms
we employ in the inquiry we are now about to make, we
will suppose that we are examining and speaking of a
voltaic cell, with zinc and copper electrodes, and with
water acidulated with sulphuric acid as the electrolyte.
In such a cell the action is as follows. The acid molecules
of the electrolyte, that is the oxygen of the water, and the
sulphuric acid in the water, that are touching the zinc,
combine with it, and this sets free basic hydrogen mole-
cules from the water; and the acid molecules next to these
basic molecules so set free combine with them, leaving
their companion basic molecules: and so at each combina-
tion at the zinc an interchange and combination is made
193 13
194 ELECTRICITY
all through the liquid to the copper, where basic molecules
of hydrogen, deprived of their acid companions, are set
free. This interchange is the electric current and it passes
through the liquid with great speed, while the molecules,
at each interchange, move one molecule's breadth, what-
ever that distance may be, say a hundred millionth of an
inch : and the entire movement, though actually progressive,
may be called simultaneous for such short distances as
we can observe in our experiments.
It was for long supposed that electricity travelled
through electrolytes and along conductors at the same
speed as light, but this has been found to be an over-
estimate. The experiments to find the velocity of the
current have hitherto been made with wires, that is with
the liquid air coatings of wires, and the rate of conduction
has been found to be at the rate of about twelve hundred
miles in a second. If a compound substance with less
density and less cohesive inter-attraction of molecules
could be found, the rate would doubtless be greater, for
obviously the rate must depend on the molecular resistance
to change, but probably there is no more easily acted on
substance than liquid air. The density of water is less
by more than a half, but its molecules are very strongly
chemically combined and must therefore offer much more
resistance to separation and a slower transmission of
current than the molecules of liquid air held together by
contact alone without chemical combination.
The molecular interchange in the electrolyte is not pro-
duced by any wave of the liquid. The fastest vibration of
water is that of sound, which travels through it at the rate
of four thousand feet, or about three-quarters of a mile,
in a second, while the vibration that causes this electrolytic
interchange travels perhaps twelve hundred miles in a
second. It is a vibration of the aether that is associated
with the molecules of the electrolyte, and is produced by
ELECTRICITY 195
the shock of the coming together .of the acid and basic
molecules at the anode .
Each molecule as it joins its new partner, whether at
the zinc or in the fluid, is drawn to it by cohesion with
constantly accelerated motion, so that they meet with
a little clash : this sets the aether vibrating and this vibra-
tion is the electromotive force, and it is through its pro-
pagation as a vibration that the molecules separate. Each
vibration produces one molecular change, and each com-
bination one vibration.
The molecules are separated by the aether vibrations
and they reunite by chemical attraction, and the double
action of the molecules is the current movement, and this
electrolysis and the electromotive force, together are
electricity. Electricity is due to the conjunction of acid
and basic molecules and every phenomenon of electricity
can be shown to be produced by this.
Electricity must not however be confounded with
influence, induction, or Hertzian waves, which are pro-
duced by electricity and are forms of electromotive force
as has been explained in the chapters on these subjects.
Neither chemical action of itself, nor electromotive force
of itself, is electricity. Nor is electricity the same as
magnetism so far as we know.
There is a general agreement that electricity is not
material. Its speed of translation is very great, and no
material has been found in any situation with speed at
all approaching it. A meteor entering our atmosphere
with a speed of twelve miles in a second is consumed at
once, and as we have no authority for assuming that
material in any condition is not subject to the ordinary
laws of nature, we must conclude that it is impossible that
molecules should travel a hundred times as fast with no
sign of disturbance of any kind, and we may reject any
idea that assumes any faster movement of these particles
196 ELECTRICITY
than the very slow movement of them that has been
discovered in electrolysis.
Electric force has an attachment for material: it is,
inseparable from material: but it uses it as a path, or as
we say, as a conductor, and not as a crutch or vehicle.
The following will illustrate the meaning of this. When
we strike the end of an iron rail with a hammer, any light
weight, suspended by a string and touching the other end
of the rail, flies away from it at the instant, apparently,
that we strike: and although we have seen no motion in
the rail, there certainly has been a minute movement of
all the particles of iron in succession from the point struck
to the other end: and while the movement has passed
through in an instant, no particle has moved sufficiently
for us to detect movement. The force of electricity acts
like this force of percussion: it uses the material to conduct
it but is no part of the material. It is a force dependent
on and inseparable from material, but no more material
than any other force is. Electricity is a swift force of
electromotive vibrations combined with slow electrolytic
material movement: and these two movements are inter-
dependent on one another: electricity cannot pass beyond
material and there is no electricity in space: there can be
none in the aether because it is not electrolytic.
Some persons write about force or movement in a loose
way as if these things could exist without matter and we
must beware of ill-considered wording. For instance, one
might carelessly say, that a point having little mass, has
little attraction of gravitation, or cohesion, and that
therefore " electricity escapes from it." Which sentence
as it stands might be taken as a statement intended to
convey the idea that electricity is material: for material
is subject to gravitation while motion is not. There are
several sentences which should occupy the place of the
word " therefore/' What escapes from the point is
ELECTRICITY 197
material oxygen or nitrogen, and their movement produces
a wind, which carries the dust of the air with it, and this
discharges the electricity by convection.
The electric force that decomposes and that which is
evolved by the recomposition of a certain quantity of
material are alike. Faraday found that " the chemical
action on one equivalent of amalgamated zinc by dilute
sulphuric acid, produced that quantity of electricity which
passed through water decomposed one equivalent of it."
This shows that electric force is an extraneous force and
not any inherent property of material.
There has of late been a return to the emission theory
for all those phenomena that we have been taught to
consider as the products of vibration: there is even a
much advertised book on the materiality of sound; and
electricity being a somewhat misunderstood phenomenon
comes in for much theorizing in that direction. Matter is
made, some scientists say, of molecules, these of atoms,
these of corpuscles, these of centres of electricity which
are not matter at all, but motion. Others suppose elec-
tricity to be a " resident property of the molecules of sub-
stances, the positive and negative together in a combined
state of neutrality, but with mutual antagonism/' A
motion antagonistic to itself is not an easily intelligible
motion. And what is a resident motion ? Motion must
be given to any object, or it is motionless; and we cannot
credit the inert molecule with any power either to produce,
or to renew, or to bottle up motion. Latent force is a
myth; the force that raises a weight is not bottled up in
the weight, and there is no sunshine in either coals or
cucumbers.
In all our examination of our subject we have seen no
faintest sign that material has any electricity of itself,
198 ELECTRICITY
but always found that it has to be manufactured for it:
and always electricity has appeared as a motion and has
had to be produced by motion, and according to the motion
supplied has been the out-turn of electric motion. Ask
an electric light company to produce current without an
engine ! The force put in produces the force given out.
In electricity the force put in is always chemical attrac-
tion which gives out a force that separates the components
of the molecules of the compounds on the whole circuit,
and they must separate in such a way that they take
opposite roads, and as the only material conducting on
wires is liquid air, the oxygen and nitrogen must move in
opposite directions, and if occasion demands be discharged
as separate materials.
Many examples can be given to prove this true, that
oxygen moves along and is given off from a negative con-
ductor, and nitrogen from a positive. We have already
had one instance where the crossed wires from the terminals
of a voltaic battery became, beyond their crossing, the one
red hot from combination with the oxygen moved on to it*
while the other on which the nitrogen was projected
remained cool. How could this be explained with " aggre-
gates of electricity " ? If electricity had any heating
power it would make the whole conductor hotter than the
part of wire where only a portion of it could be supposed
to travel, and would heat both projecting pieces and not
that alone on which the oxygen moves. The heat is pro-
duced by the chemical union of the oxj^gen with the material
of the wire.
Then there is the separation of oxygen and nitrogen in
a Crookes' tube : the oxygen is discharged from the kathode
and a dark space which is nearly pure nitrogen surrounds it .
Another proof is the action in the air space between
the carbons of an arc lamp: the " positive carbon becomes
much the hotter and burns away twice as fast as the
ELECTRICITY 199
negative one/' because by electrolysis the oxygen is moved
towards and combines with the positive carbon. With
alternating currents both burn equally.
When a Leyden jar is discharged through a resistance
that quenches oscillation " the positive terminal is more
heated than the negative/' because the oxygen is moved
to the positive terminal and combines with it. With
oscillating discharge both terminals are heated.
The knobs of an oscillator oxidize rapidly in air, because
the oxygen is separated from the nitrogen at the faces of
the knobs, and combines with the metal. Ity passing the
sparks in oil, this is avoided, because the substances
that compose oil do not act on the metal of the
knobs.
Professor Nipher has lately made some experiments with
zigzag wires, connected with the ground, through which
strong interrupted currents were sent from an eight-plate
static machine worked by a motor. Photographic plates
in hard rubber covers were put at the angles of the wire,
some on the ground side and some on the machine side
of the angles.
W T ith the negative discharge from the machine " the
plates on the ground side of the angles are much more
strongly fogged than those on the machine side/' The
particles that produced this effect could pass through
f\ inch rubber, but not through glass however thin: thus
proving that they are material and not motion. They
were molecules of oxygen and they passed through pores
in the rubber but found no pores in the glass.
With the positive current and a rubber cover only y 1 ,-
of an inch thick " 9,000 spark discharges produce about
the same intensity of image, as a single spark in the nega-
tive line. And here the effect is vastly stronger on the
machine side than on the ground side/' showing that there
was some very slight reverse current due to polarization.
200 ELECTRICITY
These effects were attributed to the electron, and Pro-
fessor Nipher calls attention to the " fact " that the
electromagnetic action of these electrons on each other
" in a nonoscillating discharge is sufficient to account for
the thinning out of the spark towards the positive end of
the spark ." It is a fact that the spark thins out towards
the positive end, but to say that electromagnetism (of
which there is no proof) acting on electrons (which have
no existence) is a fact, is mere fancy. If there were any
action of this sort, the effects produced on the zigzag
wires by negative and positive discharges should be equal,
for we cannot suppose the electrons could be less active
in one case than in the other.
The fogging of the plates is caused by molecules of oxygen
whose momentum carries them off the wires at the angles.
And the nitrogen molecules, whatever their number may
be that are shot off, can produce no effect on the photo-
graphic materials.
The following is a particular problem, which we have
already noticed, in discharge by flames. " A magnesium
flame discharges negative electricity but not positive
electricity." We can answer this if electricity involves
the movement of oxygen and nitrogen on the conducting
wire, but not otherwise. The burning magnesium is com-
bining with oxygen and nothing else, and its flame en-
courages the negative current by taking up the oxygen
brought by it: but it has no use for the nitrogen sent by
a positively electrified body, and the electrolytic action
being checked, the positive current is stopped and the
positively charged body left undischarged. An ordinary
flame, in which there is some electrolytic movement can
encourage either current, positive or negative.
The following are three cases exemplifying these actions .
" Violet light falling on a metal in air electrified negatively
discharges it." Because it accelerates the separation of
ELECTRICITY 201
effluves from the metal surface, which unite with the
oxygen that collects on negatively electrified surfaces.
" But it does not discharge the metal if positively
electrified/' Because the associated nitrogen and the
metallic vapour cannot combine.
" However violet light falling on peroxide of lead
positively electrified in hydrogen discharges it." It
reduces the lead oxide and then the oxygen and hydrogen
can combine.
In two of these cases material is emitted which, by
electrolytic movement, can exhaust the electromotive force :
in the second instance there is no action because only
elementary uncombinable substances are present.
We cannot find discharge without the movement of
electrolysis. " A red-hot cannon ball cannot be positively
electrified, but may be negatively white hot it retains
neither/' The nitrogen driven by the positive current
cannot compound with the hot iron emanation, but the
oxygen of the negative current can, and renders it electro-
lytic. The actinic vibrations of white heat prevent
chemical combination and therefore prevent the acceptance
of electricity.
There is one point that you will have noticed in our
experiments, and that is that the molecules of condensed
air, or of any other electrolyte, when once set in motion,
have some persistence of motion, by which they may be
carried even beyond the influence of the electrolytic
movement.
If a very strong static current is passed through water,
certain currents are set up which can be seen if the water
has some insoluble powder mixed with it and if proper
arrangements are used. The electrolytic action in the
water is for the hydrogen to pass towards the positive and
202 ELECTRICITY
the oxygen towards the negative anode, and when this
movement is pushed very vigorously, it can carry the
water with it in two slow, but visible, streams. It requires
a great electromotive force to do this, and Mr. Armstrong
succeeded in doing this with his powerful steam electrical
machine, as recorded in the following description of his
experiments.
With two wine glasses, four-tenths of an inch apart,
filled to the edge with pure water, and connected by a
wet silk thread the ends of which were coiled in each
glass; when a negative current was sent into one glass
and the water in the other glass was connected with the
ground, " a slender column of water enclosing the silk
in its centre was instantly formed between the glasses:
and the silk was quickly all drawn over into the positive
glass " that is to say it went propelled by the hydrogen
movement.
' The column of water persisted for a few seconds
without the silk: and when it broke sparks passed."
" When one end of the silk was made fast in the negative
glass, the water diminished in the positive and increased
in the negative glass/'
" By scattering dust on the water surfaces it was found
that there were two concentric currents, the inner flowing
from negative to positive and the other positive to
negative/'
Mr. Armstrong succeeded in " causing the water to
pass between the glasses without the silk for several
minutes and at the end could see no difference in the
quantity of water in each glass. The two currents, when
the inner one was not retarded by the silk, were therefore
nearly, if not exactly, equal/' The two hydrogen mole-
cules have only the same bulk in combination as the
single oxygen molecule and can do no more work
than it.
ELECTRICITY 203
We have seen also the actions of inertia and separation
by electrolysis in the discharge in a Crookes' tube. The
gas molecules travel by electrolysis, but are thrown out
of the current when they condense for a moment on the
glass. The oxygen molecules begin their course in a
straight flight and keep that line through inertia.
The aggregate motion of the molecules in electrolysis is
certainly very slow, but each of them probably moves in
its tiny course with comparatively great rapidity, and
therefore acquires some motion of inertia. It is this
inertia probably that gives an alternating current its
power of conduction. " The continuous current loses
energy if conveyed to a distance. An alternating current
changing direction 60 to 100 times in a second can be
sent on ordinary wires ten times as far with half the loss.
The low electric pressure (voltage) of the direct current
is changed to an enormously high pressure in the alternat-
ing current, which can overcome the resistance of the
wire/'
The last paragraph seems as though it was intended to
convey an explanation, but it gives us no why or wherefore
for increase of action or of pressure, nor is there any proof
that there is increase of pressure. Pressure comes from
force used, and there is no more force used in sending the
one current than in sending the other. But conceive now
that the first impulse of the alternating current has put
a strain, beyond the point that its complete electrolytic
action can reach, on all the molecules as far as its influence
can reach, and that all these influenced molecules are
inclined in a forward direction, then when the current is
reversed they swing back, through release of strain and
through inertia, to nearly as far as they had gone forward.
Now, when the current again goes forward, it finds nearly
all its work done for it by the next forward swing of the
molecules, and it can push on for another length along
204 ELECTRICITY
the line. So with less resistance in front the voltage is
made to seem to increase.
A great deal of mathematics, including the application
of Bessels' functions, is used by scientific electricians to
assist the understanding of this fact, that an alternating
current goes farther than a direct current on a wire, but
the whole of the difference in plain words is, that in one
case a rhythmical force is applied and in the other a plain
push. And as the whole of the current is on the surface
of the wire, Bessels' functions which refer to the whole
depth of the metal surely add a superfluous inaccuracy.
From what we have learnt from the study of the numer-
ous and very varied examples that we have been able to
see or hear of, we must conclude that electricity is a
motion that has to be produced by the work of chemical
combination: and that it is no part or property of
matter.
The movement of chemical attraction of itself, or assisted
by mechanical force, produces a shock in the oxidized
molecule : this causes a vibration of the associated aether :
and this produces electrolysis which passes as a wave
through the circuit. Without these movements and an
electrolytic circuit to carry on the movements, no current
of electricity can be produced.
The word vibration is used for the movement induced
in the aether in electrolysis because there is no other word
that is convenient. If we have a ball suspended by a
string or fixed at the end of a spring, and we strike the
ball, it will move backwards and forwards and make what
is called vibrations: but the same stroke given to a ball
lying unconnected will cause no such vibrations of it. It
is this latter form of movement that has here been called
vibration in the case of the aether action in electrolysis
ELECTRICITY 205
there is a forward movement and no return, and each
movement produces just so much effect as the effect that
produced it the movement on one molecule produces a
similar movement in the next molecule and goes no farther,
because its force is used up in the reproduction of
movement!
ELECTRICITY
CHAPTER XXVII
FLUID IS THE CONDUCTOR ON SOLID CONDUCTORS
THERE is no need for us to go over again the old story
and show proofs that substances have coatings of liquid
air upon their surfaces, and that when these coatings are
dissipated by heat, that the substances refuse to accept
electricity, and are useless as conductors: so we will,
without more words, consider the manner in which elec-
tricity is carried along a wire by the electrolytic action of
the molecules of the liquid air on the wire.
From all the experiments that we examined in the study
of conduction and elsewhere, we came to the conclusion
that electricity is conducted along wires by electrolysis in
their condensed air coats, in the same manner as it is
conveyed through the electrolyte in a voltaic cell, and that
any action on the metal of the wire, resulting from the
passage of the current, is due to the interaction of the metal
surface molecules with the condensed air coating.
If we work an electrical machine and connect the chief
conductor as well as the amalgam with the earth, thus
making a complete circuit, all the electricity we choose
to make goes into the earth along the wires and is cancelled,
and there is no result except that the conductor wire is
somewhat heated. This does not result from any electrical
heat, but from the electrical action, which entangles or
brings in some way some of the surface molecules of the
metal into combination with the liquid air upon the wire :
their combination produces contraction, and their con-
traction evolves the heat which is transferred to the wire.
206
ELECTRICITY 207
The more easily the surface molecules are detached, the
greater the waste of electricity and the greater the heat.
The finer the wire, that is the smaller the condensed air
channel of conduction, the more the metal is called upon
to act and the greater the waste of metal and electricity,
and the greater the heat. The wire if very fine is quickly
burnt away : it is not melted but is destroyed by chemical
combination of the metal with its fluid coating.
" None of the heat of the wire appears in the cell/'
Because all the heat produced in the wire is local and soon
dissipated into the air: and there is no heat from the
action in the cell, because the aether vibrations produced
by the clashing of the combining molecules are not heat
vibrations but impulses of much greater length than the
longest heat vibrations. Electricity can give no .heat
directly, but makes it by the chemical action that it helps
to bring about on the wire or other conductor. The heat
of the spark or of the lightning flash is not electrical but
chemical from the burning of the conducting air. The
heat of the arc light is chemical from the burning of carbon
and air. There is little heat on a good conductor as there
is little chemical action of the metal, and all the light and
heat of electric circuits is due to chemical change of the
conductors, and almost certainly to that alone, for friction,
which is sometimes quoted as a cause, is also an inciter of
chemical combination.
Wires that are used to convey electricity become what is
called rotten after a time, because the cohesion of their
particles is reduced, and this is sometimes ascribed to the
current, and quoted as a proof that the substance of the
wire carries the current, though how it is supposed to act
is not told. It is much more probable that the weakening
of the wire is owing to alternate heating and cooling.
A piece of iron alternately heated and cooled many times
can be made to grow forty-five per cent, in bulk: and its
208 ELECTRICITY
loss of cohesion and consequent rottenness is certainly
proportionate.
There is always some loss of electricity on the conducting
wires. Even if we had a perfect conductor the current
could not pass along it without some loss. Each impulse
of the electromotive force exhausts itself in the work of
dividing a compound molecule,, and though each recon-
struction of a molecule should revive the force, we cannot
but think that the overcoming of inertia must dissipate
some of it; and besides, all along the conductor some of
the force is used in setting up induction waves and is thus
radiated away. But for these we might have perpetual
motion if we could find a perfect conductor, as it is our
materials act very imperfectly and variously and some
resist the strongest impulse that can be brought to bear
on them, still on a good conducting wire electricity will
go far.
In what way can an electron act to carry the current
or to resist carrying it ? It is supposed to be a little pellet
shot out of a molecule, or else wandering between the
molecules. In an inch of electrolyte there are a hundred
million molecules to obstruct the shot: can you suppose
that this little cannon has force to drive its shot through
this inch, not to mention a thousand miles ! Or, looking
at our calm electrolytes, can you believe that material is
rushing through it at the rate of twelve hundred miles in
a second. Only with aether vibration can such velocity
be obtained.
If the molecule can fire its electron to even the smallest
distance, then why should it require many hundred times
more force to send it through gaseous air, than through
the sixteen hundred times denser liquid air ? And how
is it that a little silk thread wound round a wire, or the
thinnest sheet of paper, is able to stop conduction ? These
things stop the electricity, not by entangling electrons,
ELECTRICITY 209
but because the condensed air on their fibres does not form
a continuous liquid conductor.
In no direction do we find any indication that electricity
is material in the remotest degree, while all we learn about
it points to its being motion only.
The rate at which a current passes along a conducting
wire has almost nothing to do with its material, or its
length, or its thickness. "If an oscillating discharge is
sent over a bifurcating wire the ends of which are set
close together, there will be a spark between them if the^
two branches are of different lengths, but if they are equal,
there will be no spark, whether the two are of the same or
different metals/' The rate at which the vibrations travel
through the liquid air on the conductors is unchangeable.
All that the material has to do with the conduction of
electricity is the distance that it will conduct before its
resistance changes the impulses to other work. When
they say that the rate of the current through deep sea
cables varies from -932 to -292 of a second for a thousand
nautical miles, these measures really represent the time it
takes to charge the covering sheath of the wire inductively
in successive lengths by the diversion of the electromotive
force. The rate of the impulse, while it remains an im-
pulse and unconverted to other work, remains unchanged.
According to some theorists " the medium round the
wire is the conductor of electricity, and the wire is merely
a guide to the current flowing outside it " : and when there
is resistance and waste of energy by change into heat, it
is said to be due to " the energy flowing laterally from the
medium into the wire/' As aether is a perfect noncon-
ductor, the medium referred to must be air, though how^
this can be imagined it is difficult to understand, for we
know that air is one of the worst of conductors, and requires
an intense force to compel it to act, and does so with
intense heat, and light, and noise, whereas a good conductor
14
210 ELECTRICITY
requires no coaxing, but at once conveys away enormous
charges with scarce a sign to show for it.
In those interesting experiments, with electrified wire
gauze, invented by Vanderfliet, we saw that the force
acted on the outside curves and was wanting in the hollows.
If any extraneous medium had the regulation of the
electricity about the gauze, it should act indifferently
everywhere. One can understand that if the electricity
is an affair of the gauze, that it should by its mutual
repulsion leave the inside of the loops ; but if it is extraneous,
why should it be ruled by the gauze, why should it not
by its repulsion leave the gauze altogether ? The elec-
tricity acts as an appendage of the gauze and not as if it
worked in any separate medium.
And then about resistance. What would make the air,
or for that matter any conceivable outside medium, round
an iron wire, resist the current six times more than the
same medium when round a copper wire: and why should
electricity flying in one direction, take the trouble to turn
its direction at right angles merely because of a change
in the metal of the wire conductor ? And why should
heating a metal conductor prevent its acting not only
when hot but for some time after it is cold, if anything
but the liquid air coat on it does the conducting ?
The molecules of air are mixed, not compounded, but
conduction on metallic or other conductors requires that
they should be joined in groups in some way, in order that
a dissociation and recombination similar to .electrolysis
should occur to enable the current to travel, and this
collection in groups appears to be what must actually be
the arrangement, for if the gases of our air were not asso-
ciated somehow, they would as surely separate as oil and
water, the heavy oxygen would settle below and the lighter
ELECTRICITY 211
nitrogen would rise; but air, whether taken from heights
or depths, has been found everywhere to have the same
invariable percentages of these gases. Professor Lodge
says that the " molecules of air contain approximately
25 to 28 corpuscles/' That is to say, putting it into the
language that we have been using, and substituting
molecules for corpuscles, the air is probably composed of
groups of five oxygen and twenty nitrogen molecules,
held together as a compound molecule by mutual cohesion,
but not chemically combined: and this combination is not
changed when the air condenses to a liquid; the com-
pound molecules are then merely liquid groups instead of
gaseous, but being some sixteen hundred times denser as
liquid, they hold together with so much the more cohesion.
Chemical attraction no doubt causes deformation and
extended contact of the molecular surfaces pressed together,
and a spark in air produces this actual chemical combina-
tion as is shown by the nitrous products resulting: but in
liquid air the cohesion of the groups is probably due to
mere contact without deformation, and this accounts for
the ease with which electric force separates the members
of the groups and also shows why liquid air is the favourite
conductor of electricity, which is simply because all other
compound liquids have chemically compounded molecules
which are less easily acted on.
All the evidence shows that electricity is conducted
electrolytically in the condensed air on wire conductors:
and in no case can there be such conduction unless this
fluid or some other is present. Doubtless other fluids
would act similarly and more or less effectively if they
were on the wire, but they are generally absent and the
condensed air present.
Fluid is the conductor on solid conductors.
ELECTRICITY
CHAPTER XXVIII
INFLUENCE
FORCE cannot act without the assistance of material, and
the only way in which force can act at a distance is by
movement of the intervening medium: and where the
force acts without movement of sensible material, it acts
by vibration of the insensible aether. To suppose that
the action of influence at a distance is caused by such
objects as ejected electrons, or other emitted material,
is to return to old and exploded emission theories which
present knowledge has made impossible of acceptance:
and as it is equally futile to suppose that a perfect fluid
like the aether should have any translational power, we
must look for the cause of attraction and repulsion of
electrified bodies elsewhere than in any mechanical trans-
mission, except only in that of vibration of aether.
Some people seem to think that the attractions and
repulsions between electrified objects are due to lines of
force, and speak of these lines in such a way as to suggest
that they are material rods which can act in the same
way as an oar or boat-hook when used to stave off or draw
a boat to a ship's side: but Faraday when he invented
these terms surely meant direction and nothing more.
The force of influence is a vibration of the aether, and
neither the aether nor its vibration has power to push or
pull material. Still these rays of force produce vigorous
and immediate movement of material along their lines of
direction: so it is plain that some action must be set up
on the material which causes the material to move: and
212
ELECTRICITY 213
as there is no pull or push in the medium, the pull or push
must be an action of the material acted on: and as aether
vibrations can only act on molecules the action of the
material must be due to a molecular movement on its
surface. You may liken it to the working of the wind on
the sails of a ship : they are attached to the ship and move
the ship one way or another according to their arrange-
ment: the wind acts on the sails and they push the ship.
The vibrations act on some part of the material and that
pushes the whole material.
The first lesson we learnt in electricity was, to rub a
stick of sealing wax on our coat sleeve and hold it over
small scraps of paper to see them fly up to the wax and
then fly off again: and next we attracted a little feather
hanging by a silk thread, which after it had left the wax
could not be caught by it again. We read of these little
experiments in every book on electricity, and are told,
that it is because of the attraction and repulsion of elec-
tricity that these things happen and nothing more.
There is no attempt at any explanation: and yet in the
explanation of these anciently discovered facts lies the
whole explanation of electrical influence and induction:
attraction and repulsion.
Before we seek an explanation of these facts it is necessary
that we must know what the action is that is going on
upon the surface of an electrified body and that is pro-
ducing the movements of attraction and repulsion of the
body.
A body can be charged with only one sort of electricity.
On every charged body there must be some movement
going on to produce influence vibrations: the movement
is over the whole body, because the influence radiates
from all parts, and in all directions : it is a slow movement,
for a charge will last for hours though it is dissipated in
an instant by conduction; all movement is reciprocal, if
214 ELECTRICITY
you push or pull, you push or pull yourself with equal
forqe and in the opposite direction to the movement you
give : the proof plane shows us that the action on electrified
bodies is more intense at the ends of elongate bodies and
on the edge of a plate than at its middle: therefore the
molecular movement is outward from the middle and
being equal on opposite sides it cannot move the body:
but if the movement at any part could be increased it
would move the body in the opposite direction to that in
which the movement itself moves.
Remembering these generalities let us now consider the
particular cases.
The negatively electrified wax that we are using, sends
out negative influence waves that cause an electrolytic
movement with separation of the positive and negative
electricities on the feather, and by increasing the negative
movement away from the wax the feather is pushed towards
the wax.
On touching the wax, the positive electricity on the
feather is cancelled by some of the negative on the wax,
and the whole feather is then negatively charged. Any
influence vibrations sent out by the wax to act on the feather,
will now incite the negative molecular movement on the
nearer part of the feather more strongly than it can that
on the further side, and the feather will be pushed away
from the wax.
The common saying that like charges repel and unlike
attract, is quite wrong: the charges have nothing to do
with it except the providing the influence waves that
produce the apparent attraction and repulsion. The
charges on two bodies similarly electrified send out in-
fluence vibrations that incite the molecular movement
more on the nearer sides than on the further sides of the
charged bodies and the bodies are pushed apart: while the
influences of unlike charges incite each a molecular move-
ELECTRICITY 215
ment away from the exciting body and the bodies are
pushed together.
In fact there is no such action going on as attraction,
for what seems to be attraction, and repulsion as well, is
a pushing about of material, and all that we see might be
called propulsion.
We can now understand why a charged bubble expands ;
it is not by any expansion of the air in it, nor by push of
rods by force, but because the influence waves in the
interior mutually intensify the molecular movement
towards the interior and thus push the material out-
wards.
The following is an extract made from a report on
atmospheric electricity in America, and refers to the
stream issuing from a Kelvin collector during a storm.
" Previous to the lightning the stream from the collector
was twisted and split into many fine threads and sprays,
but instantly with the flash it became a single jet, and
remained so for a few seconds, then gradually becoming
more distorted until another flash occurred: there was also
cessation of sparking between the collector and the ground
wire at each flash/' The stream was highly charged
between the flashes, but it carried no electricity when the
flashes had for a time restored electric equilibrium. The
reason for the distortion and separation of the water jet,
was the action of the influence waves, which acting on
every irregular depression on the surface of the jet forced
it to divide.
It is by the driving away produced by unlike charges
that dissimilarly electrified bodies are pushed together and
their electricities cancelled, but whenever by the inter-
position of a nonconductor the cancelling is prevented,
the different electricities are held, pressed as it were,
against the two sides of the nonconductor, and charges
so placed are said to be bound: they interact mutually by
216 ELECTRICITY
means of their influence vibrations which pass through
the nonconductor and in this way they will accumulate
on the faces of it in much greater strength than they can
be made to do as single charges.
The positive charge in a Ley den jar sends out waves of
influence, which, carried by the aether, pass through the
glass and influence and carry away the positive charge on
the other side of the glass, and leaves the negative on
which they have no action upon the glass, and mutual
influence thus pushes the unlike charges together as near
as possible.
If two Ley den jars are charged, the one positively and
the other negatively, and they are placed with their outer
coatings, which are negatively and positively charged,
touching one another, they do not discharge one another.
The outer charges have been collected by the influence
vibrations sent out by the inner charges, and are only
sufficient to satisfy the mutual action of their rays of
influence, and none can be spared to act elsewhere.
When a conductor that is insulated is charged by in-
fluence, an electrolytic action is set up in the molecules
of the liquid air upon its surface, and according to whether
the influence is positive or negative, so is the direction
and position of the negative and positive action produced.
If the influencing body is positively charged, its influence .
waves cause a positive movement on the influenced con-
ductor away from the body, and a negative movement
towards it, and vice versa with a negative charge.
If the conductor is isolated there can be no current:
there is a division, or inclination of positive and negative
molecules towards the ends of the conductor and as they
can get no further the current is stopped : but the tendency
remains and may be called a strain or any other like name.
Electricity moves swiftly, but the strain is immovable
except for the slight way that it makes to fill up losses by
ELECTRICITY 217
induction: it may be strengthened by additional influence,
or it may fade away through loss by the influence itself
sends out. For it is plain that there must be a certain
amount of slow work going on upon the insulated con*
ductor to produce the influence waves emitted, and the
work must be done by the strain, and the strain must lose.
" Even if the conducting wires of a cell are not joined,
the wire of the zinc is negative and of the copper positive,
there being a tendency for the zinc to oxidize and drive
electricity through the cell/' Here what we call a strain
is called a tendency, and the same tendency is found in
all isolated bodies charged with electricity, or arranged to
produce it. The ends of a voltaic pile are differently
electrified : the zinc end positive and the gold end negative ;
and this charging of the ends could not have happened
unless there had been a tendency to movement in those
directions. " The action of the voltaic pile is cumulative
and nearly disappears on discharge/' This accumulation
and charging of the ends has happened, although there
has been no current, because there has been a strain and
gradual movement due to it.
The eye can detect no movement in the electrolyte in
a voltaic cell, but the fluid is found to be doubly refracting
from the strain produced by the electromotive force. And
" glass when subjected to a severe electrostatic stress
undergoes an actual strain which can be observed by the
aid of a beam of polarized light/' This change in refrac-
tion takes about half a minute to attain its maximum
in solids, from which it gradually dies away when the
electromotive force is removed, but in liquids both effects
are instantaneous.
What then is it on which these strains act, and what are
positive and negative molecules ? They are certainly
substantial or they could not push or pull, and they are
substances that by intermixture become some ordinary
218 ELECTRICITY
unexcited fluid. There can be no doubt that in the case
of influence the materials acted on in liquid air are nitrogen
and oxygen, and in water that they are hydrogen and
oxygen; and if we go over this chapter again and substitute
these names where necessary, we will arrive at a very clear
understanding of the subject.
According to our ideas, the water molecule is made up
of one oxygen and two hydrogen molecules combined into
a nearly spherical globule, which, when unacted on, always
floats with the hydrogen uppermost. There is no difference
in the sizes of the oxygen and hydrogen molecules before
they combine, but when they combine and the three
molecules are compressed to the volume of two by the
force of chemical attraction, the hydrogen suffers most
because the oxygen has sixteen times its specific gravity,
so that the water globule should be represented as a
hemisphere of oxygen with two quarter spheres of hydrogen
above it. The effect then of an electrolytic strain would
"be to push the hydrogen molecules one way and the oxygen
the opposite and to change the water from a fluid in which
all the molecules stood perpendicularly to one in which
they leant diagonally : and this is what gives the distortion
which produces double refraction in the water electrolyte.
The refraction change in glass under " severe stress " is
due to a similar change, but owing to the greater cohesion
of the solid molecules is much more difficult to bring about
than in water, and the relief for the same reason is slow.
No doubt repetition of the stress and its relief would soon
make the glass rotten.
A great deal is made of the Zeeman effect as confirming
the electron theory. But it is only a strain produced by
a strong current with distortion of molecules and conse-
quent polarization of light : and it is of no more significance
than the same effect in the liquid electrolyte. In fact it
is another philosopher's mare's nest.
ELECTRICITY 219
Influence, then, is a vibration of the sether: produced
by the electromotion of molecules: producing electricity
in molecules : producing it of the same sort as the electricity
that sent out the influence vibrations: and therefore there
are two sether waves of influence, a positive electricity
producing wave, and a negative electricity producing wave.
ELECTRICITY
CHAPTER XXIX
TWO ELECTRICITIES
ELECTROMOTIVE force is a vibration acting on the molecules
of compound liquids and gases, and reproduced by their
reversion to the state from which its action changed them.
It cannot therefore be a vibration of material and must
be a vibration of the aether associated with the material.
The vibration changes the material: the reversion of the
material reproduces the vibration. It is the aether that
vibrates: not the material. The material is fastened to
its place; the aether vibration radiates free.
When an ocean wave, half a mile long and thirty feet
high, approaches a motionless ship/ it first draws the ship
towards it, tilting it at the same time in the direction in
which the wave is going; then it drops it back almost to
the same place as at first it occupied, at the same time
tilting it away from the departing wave; and if two or
more ships were side by side and broadside on to the wave,
they would be considerably jostled together. Now the
molecules of liquid air, which we suppose are assembled
in groups, assume a position with respect to each other
similar to that of the ships at rest, because in all of them
the heavier oxygen must hold the lower place: so, though
we do not know how the induction or electromotive aether
waves act on the molecules, it appears probable that the}'
act in a manner comparable to that of the ocean wave on
the ships. And compared with the molecule these waves
are immensely greater than the sea wave compared with
the ships, and also immensely more swift and frequent.
220
ELECTRICITY 221
And if the oxygen molecules are violently tilted against
and entangled with the nitrogen of the next group, and
this happens all along any ordinary conducting line practi-
cally at the same instant owing to the extreme velocity
of the wave motion, and recurs with every wave : then we
can understand how a current of electricity is established*
with a continued movement of oxygen molecules in one
direction and of nitrogen in the other.
Now what is called influence produces a separation of
the particles of molecular groups, the force acting in every
way the same as the electromotive aether wave. For we
find that there is the production of strain and of action
by both, and they neither of them do more than this. We
have seen the effect of influence on conductors, though not
as yet any special examples which we can say are parallel
to the effect of the spark in air, and in fact influence only
begins that action and has not the power to finish it. Still
so far as it goes the action is similar. The electromotive
force puts a strain on the electrolyte and if it is strong
enough, causes complete electrolytic movement and con-
duction; the influence wave causes a strain in the electro-
lyte, but can do no more.
With a small voltaic battery we cannot produce but a
tiny spark in air, but if a spark discharge is being made
near at hand, the battery can discharge a spark half an
inch or more in length. Plainly the electrolytically
inclined air is put under a further strain to electrolysis by
the influence waves from the spark discharge, and this
helps the discharge of the battery. And again, when a
body is charged, the electricity it receives is certainly
given by the action of the electromotive force, and as
certainly that body then sends out influence waves that give
electricity to other electrolytes, thus again indicating that
the electromotive force and the influence wave are identical.
" Electromotive force is that which moves electricity."
222 ELECTRICITY
It is often difficult to follow up the meaning of anagram -
matic sentences such as this, they may mean what we
mean, and again they may not. Most scientists seem to
include both current and electromotive force under the
term electricity, and as we have done so up to this, we
will continue to use electricity as meaning the whole effect :
current as specially meaning the action of the electrolyte
whether gas, solution, or liquid air coating: and electro-
motive force as the wave of motion that propagates the
excitation started at the place of manufacture of the
electricity.
Whatever the electromotive force may be, it is not a
wave of the material of the electrolyte, whether that be
gas, the fluid in a cell, or the fluid on a wire. It is no
vibration of molecules, and has as little to do with them
as the sound of a bell has to do with tne bell and bell-
clapper that produced it, or the air it moves, or the ears
and nerves it acts on. A force is movement, and move-
ment is not material. However much the bell may waver
after the blow of the clapper, it is not because the clapper
has put some fresh material into it, but because it has
transferred motion to the bell. Experiment has shown
that the electromotive force can pass through material at
the rate of twenty-four thousand miles in a second, and
experience has also shown that any movement of molecules
to even a two thousandth part of the distance in the same
time will dissipate them by heat in a moment. So we
may safely believe that the electromotive force is an aether
wave, and that it is carried by the aether associated with
the molecules of its vehicle.
Why the wave of electromotive force prefers to keep
to the aether associated with fluids, is because they are
compound substances, and because in them electrolysis is
more easily started than in gases or solids. Other waves
also have their preferences: the sound wave prefers to use
ELECTRICITY 223
the air, and heat waves prefer solids : and all for the same
reason, that they can act on them more easily than 011
other substances.
Electricity is often said to be like heat and they are
alike in some things, but in others utterly different. Both
of them are an interaction between vibrating aether and
molecules. The aether waves of radiant heat, acting in
some way on the molecule, cause it to change, and so also
the electromotive aether wave produces a change in the
molecule. The molecule in reaction from heat may repro-
duce heat waves or others of higher rate of vibration, and
the molecule in reaction from electricity may reproduce
electromotive or other waves.
Between bodies equally heated no heat can pass, and
" between places of the same potential no current will
flow/' When a substance is acted on by heat, its molecules
expand, and so long as it is in contact with no colder
substance, they remain expanded although they must be
under a strain to get rid of the expansion. When a substance
is acted on by electricity something happens to its mole-
cules which puts them under a strain, and so long as they
are out of connection with differently strained bodies they
retain the strain or lose it very slowly by influence.
Beyond this there is no comparison between heat and
electricity. Heat results from the contraction of molecules,
electricity from their percussion. The conduction of heat
is slow, while that of electricity is instantaneous. Induc-
tion of heat is slow, of electricity quick. Heat will invade
solids easily and liquids with difficulty, electricity uses
liquids but can make no use of solids. Heat generally
produces chemical union, the electric wave causes disunion.
What is chemical union ? The cohesion of molecules.
The junction of the outer surfaces of molecules according
to some particular shapings of the molecules: a conjunction
in which the molecules are not destroyed by intermixture,
224 ELECTRICITY
but merely associated by contact. A meeting of exterior
surfaces only. Heat we believe to be an expansion of the
molecule caused by vibrations of sether acting from within :
electricity is evidently an action of the vibrations of sether
acting outside the molecules and caused by the coming
together of their surfaces.
Are there two electricities or only one ?
In induction there must be two sorts of vibrations as
there are two effects: whether the induction wave is posi-
tive or negative it can be polarized: they act differently,
the one wave acting to carry the nitrogen molecules with
it, and the other to carry the oxygen : the one acts on the
basic molecule only and the other on the acid: the one to
act on the molecule occupying the upper place in the
compound molecule and the other to act on those below.
In the voltaic cell there are plainly two effects: the
oxygen molecules go to the anode and the hydrogen to
the kathode,, and to do this there should be two causes.
When the oxygen and zinc combine they produce vibra-
tions of electromotive force. Now it is not easy to believe
that these vibrations radiate in one direction only: they
will if they have a limited channel to work in, such as a
conducting wire, be obliged to confine themselves to the
channel, but they will radiate in two directions from the
point of origin, and if they produce different effects, as
is the case, they must be different vibrations : one produced
by the zinc, and the other by the oxygen.
If we have an electrical machine placed in front of us
so that the earth wire from the cushions is to our left
hand and a wire from the conductors to the earth on our
right: and if we interrupt the currents in these wires by
making them pass through vessels filled with an electrolyte
say solution of sulphate of copper the effect in both
ELECTRICITY 225
cases is that the copper is deposited on the right hand
electrode in each vessel, precisely as though these repre-
sented the anode due to a single current in one direction:
or as it might be argued, that the negative and positive
vibrations are identical. But the acid in the electrolyte
also moves though we may not see it: and the inquiries
that we have made oblige us to conclude that there are
two opposite currents in the circuit, the one pushing the
copper in one direction and the other pushing the oxygen
and acid.
If we isolate the machine and put the ends of the wires
from the cushions and conductors in Ley den jars, we get
the jars charged with two different strains negative and
positive which can only be due to two different current
actions. And here the action is entirely confined to the
machine and there are no earth currents to explain away
the difference in the charging of the jars.
We can divide the charge in either jar with an empty
jar with sparking between the knobs, proving that either
strain can produce the full electric effect.
If we put one of our sausage-shaped conductors between
the wires of a battery, the current uses it as part of the
channel of conduction. If now we remove the negative
wire and after that the positive, we find that the conductor
has a small charge of positive electricity: and we can give
it a small negative charge by removing the positive wire
first : no doubt also we would leave it uncharged if we could
remove the wires at the same moment, only we can never
do this, and we always find one or the other charge on the
conductor. The charging of the conductor in any case is
due to strain, and it shows that there are two strains, and
consequently two movements of electromotive force.
The ends of a voltaic pile are differently electrified, but
the middle is neutral. This could not happen if there were
not two electricities.
15
226 ELECTRICITY
There are stationary waves produced by the interaction
of positive and negative induction waves, which confirms
the conclusion that the positive and negative electricities
are one production, but different motions.
Bruno Kolbe found that a loop of wire, carrying the
current between the prime conductors of an influence
machine, when tested with a proof electroscope, showed
strong excitation near both conductors, positive or negative,
and that when the electroscope was pushed further along
the wires away from the conductors, the leaves declined
until, at a point about halfway, they fell completely
together. Professor Trowbridge discovered that " when
a long wire is charged, a point in it may be found where a
peculiar crackling sound is loudest, and where an exhausted
tube lights up, and there are also spaces where the parallel
wires, in a long loop, may be connected without impairing
the brilliancy of the light in the tube." In both these
cases the want of effect was due to the want of electrifica-
tion on the wire at those points. This, is hardly to be
explained with one electric wave in one direction, but
with two sets of vibrations, not quite in harmony, we should
be certain to find that just this interference must happen.
The points where the electricity is wanting are the nodes
of no action from the effects of the two sets of waves
cancelling one another.
Still even with this before him, Kolbe will not allow
himself to be moved from the old groove, and says, " there
need not necessarily be two electricities. One set of
substances may cause right hand spiral currents of electro-
lysis and another left hand, which coming together would
cancel one another." It seems rather an unnecessary
complication to introduce supposititious spiral currents,
but this is certain, that whatever may be the form of the
electromotive waves and the currents that they produce,
there is no set of substances which, in electrolysis, produces
ELECTRICITY 227
only a positive action or a negative, but they all produce
both positive and negative, and continue to do so from
start to finish, and produce both electricities in equal
quantity.
Kolbe also adds, " Therefore both sorts of electricity
reside in an uncharged body, and positive electricity is
a superfluity and negative a want of electricity in com-
parison to surroundings. A and B rubbed together, an
excess is produced in A and a want in B. Therefore as
we can by influence or friction produce an unlimited
amount of electricity, we must suppose that some im-
ponderable substance exists in space that makes good the
loss in one body and this can be nothing but aether,
which acts as in the case of heat, which continually supplies
a body which by conduction loses temperature." He has
quite lost himself here. Heat is produced by aether waves :
and no body loses heat by conduction unless it is hotter
than its neighbours, nor gains heat except from heat
vibrations. And the substance by which the loss through
electric production is made good is the air: no body can
be charged if cleared of its air skin and placed in aether,
or hydrogen, or even if heated in air: nor will two such
cleaned bodies produce any electricity by friction or
otherwise.
The aether heat wave, or the aether induction wave, acts
upon the molecule, and it, in recovering itself, produces
a heat wave, or light wave, or electric wave, as the case
may be: there was nothing in the molecule to begin with,
and what it produces is a new creation. The molecule
cannot create a force: it can only receive a force and be
changed by it, and in recovery reproduce an equal force
either similar or different from that it received. Electricity
is not a residential property but is a product of force,
and it does not exist before it is made.
" The oscillations found on discharging a Ley den jar
228 ELECTRICITY
with a short wire, seem to confirm Franklin's idea that
there is but one electricity: + being an excess, and a
deficit of it." We might however equally well say,
nullify Franklin's idea, because the excess of motion of
the molecules at each swing causes an inversion of the
two electricities of the two electromotive forces.
Fill a glass jar to two-thirds of its height with acidulated
water, and put it to the same depth in a bowl of acidulated
water to which add an earthed wire. Charge the jar
positively for an hour : discharge it and charge it negatively
for ten minutes: remove the earthed wire and discharge
it again, and then, at short intervals, measure the force
and direction of the current produced by the residuary
strain left in the glass of the jar. It will be at first negative,
then declining in force it will disappear and change to
positive. There have evidently been two strains pro-
duced in the glass. Now two similarly consecutively
recovering strains can be produced in material by
mechanical force: but it needs to be done by two
different forces.
Most persons say that there is only one sort of electricity,
and every one speaks of two, but surely we have now
assembled sufficient facts upon which to base an opinion
as to whether one or other or neither are right.
What then is electricity ? What is the impression that
the studies we have undertaken has made upon you ?
The following is surely your united decision.
Electricity is vibration of the aether that is associated
with the surfaces of conjoining molecules. Produced by
conjunction of molecules : transmitted with conjunction of
molecules: and consisting of two currents, the directions
of which depend on the position and relation to one
another of the conjoining molecules. And as there are
two vibrations and two currents, there are two electricities.
(Conjunction of molecules, that is the drawing together
ELECTRICITY 229
of molecules by gravitation, produces electricity, but
only under certain conditions. The force of the gravitation
must be comparatively feeble. Chemical conjunction
produces electricity only when it acts mildly: violent
chemical union produces not electricity, but the more
rapid vibrations of heat, light, and actinism.)
RAYS
CHAPTER XXX
THE RAY DESCRIBED
Is it necessary to explain what is meant by a ray ? When
we see a picture of a saint with beams streaming from his
head, we understand that they represent, not fixed
material ornaments or puffs of vapour, but light which is
constantly produced and sent forth by some property of
the saintly one's head, from which it streams away in
straight lines never to return. The painted streaks are
intended to be taken for beams of light, and beams of
light are radiant lines of aether vibrations that illumine
material.
But besides these light rays there are other rays which
have no light-giving power. " The carbon arc light
when unshaded scorches and blisters the skin and pro-
duces active inflammation of the eyes even when protected
by double thick grey glasses which remove all the dazzling
effects of light." The harm is done by the actinic set her
rays which cause chemical decomposition, and which
cannot be cut off by grey glass, but can be cut off, that
is changed, by other mediums.
The rays produced by heated bodies are another set of
aether vibrations and are not streams of material.
And the rays of influence produced by electrochemical
means are also lines of radiant aether vibrations, and it is
about them that we are now inquiring, and some are
made visible and others not.
A ray, however it may have been produced or whatever
effect it may produce, is a wave motion in the aether and
230
RAYS 231
not any movement of material more substantial than the
aether.
Rays are aether vibrations that flow in straight unbend-
ing lines, and physically we know nothing of a light ray
unless it directly enters our eyes. We see none of the rays
of the sun unless we foolishly look straight at it, but only
their reflection or reproduction by material substances:
the course of a ray of light is only revealed to us by its
action on substantial material such as dust or vapour : it is
not reflected by the gases of the air. It would be easy to
arrange to send a beam from a brilliant lamp through a
darkened room, in such a way that the beam should not
play on any part of the walls of the room, and that beam
would be invisible to any one in the room which would
appear to him to be absolutely dark : and if a puff of smoke
were sent into that beam, the room would be immediately
lighted up by the reflected rays from the particles of the
smoke.
But because actinic rays can act on the gases of air
a photographic film could be darkened in that dark room
by invisible reflected actinic rays.
No particles enter our eyes or act on the photographic
plate, but only vibrations of aether. The ray is not the
material acted on, but the aether vibrations that act.
Action and production are reciprocal: a ray acts on a
molecule of matter which in recovery produces a ray to
act elsewhere.
According to the theory of the conservation of energy,
the ray cannot be lost : but against this we have the action
of inertia : the ray must lose some energy in every encounter
with inertia which is a non-reproductive force, so the ray
should at last be worn out and the energy lost.
Very many ray -producing experiments have been made,
but most of them with the idea of finding new varieties
of rays, rather than for any examination of the rays
232 RAYS
themselves, or of their mode of action. The experiments
have therefore been made in as complicated a manner
as possible by varying intermixtures of chemical,
mechanical, electrical and magnetic devices, all worked
together like the mess in a conjurer's hat, with the result,
that this region of what is called electrical rays is a true
country of the coquecigrues, in which every thing is made
to appear something that it truly is not. The language
in which most of these experiments is described is what
to an ordinary outsider is a stumbling-block and foolish-
ness: some have been very carelessly described, and some
are contradictory: but we must look away when Jove
nods. They are the material we have to examine, and we
must do the best we can with them.
What we have to do then is to puzzle out the interpreta-
tion of these experiments, and it must be the true one.
For want of the true interpretation of a Hebrew text,
Moses has been represented as wearing horns instead of
rays on his forehead, and so is made to appear more in
what we have been brought up to consider a likeness to
Satan, than what we should expect to be that of the great
Israelitish high priest and leader. Misrepresentation of
the ray experiments has in like manner led to an indis-
crimination of matter and motion similar to that of Moses'
head ornaments. We must therefore take great pains
in interpreting the effect of the manipulations that produce
the rays, and the causes that lead to the production of the
rays, and the action of the rays after their production:
but in this last it will not be necessary to push inquiry
further than to show whether, what are called rays, are
in reality aether vibrations, or in reality moving material,
for the mistaking of one for the other is a common occur-
rence. One thing we must always bear in mind, and that-
is that a real ray is a set of vibrations of aether, and not
any movement of material, and we must reject any
RAYS 233
interpretation, however pretty and plausible, that
violates this rule. No puff of air, or squirt of water,
or rush of particles however small they may be, is
a ray.
Every aether ray has its definite rate of vibrations
which remains unchanged in length and frequency how-
ever strong or weak they may be: and because the aether
has no friction the rays remain unchanged however far
they may go, at any rate for such short distances as our
sun's more force would be felt near the sun because more
waves would be encountered there, but not more force in
each wave.
The sun's material sends out impulses that produce
radiant vibrations in the aether: each contraction of a
molecule on the sun sends out one impulse through the
aether: and a number of such vibrations following one
another is a ray.
The effect of an aether heat vibration on a molecule is
to expand it, and the force of vibration being changed to
work of expansion, the vibration ceases and the aether
is at rest. The molecule being under pressure from
gravitation is restored to its former size, and in being so
restored reproduces an equivalent vibration in the aether
to that which expanded it.
The effect produced upon the molecule by the vibration
rests in part with the rate of the vibration and in part
with the material and the work it allows the vibration to
do in it: and when the molecule subsequently produces
a wave in the aether, it entirely depends on the material
what sort this new vibration may be.
We call those rays that include a certain octave of
vibrations, rays of light, because we see them produce
light by acting on material, but it is certain that material
acted on by other rays beyond the light octave, does, on
occasion, produce rays of a frequency belonging to the
234 RAYS
light rays, and the new ray is due entirely to the action of
the material.
Each set of rays has been named from the principal
effect that it produces on material, and we name those
electrical that have been produced by and reproduce
electricity: but just as all the others have no heat, or light,
or actinism in themselves, but merely produce effects in
substances that they excite by their vibrations, and that
these excited substances in their turn may generally
reproduce the same sort of rays : so the electrical rays have
no electricity in them, but merely a very distinct set of
aether vibrations, which are very long, and slow in recur-
rence compared with the other aether vibrations, and which
principally produce electricity on the substances on which
they act: and the substances acted on may principally
produce these long vibrations, but may also produce in
reaction the vibrations associated with heat, light, or
actinism.
When an electric spark is made in air, it is the result
of the electromotive force breaking down the resistance
of the air to electrolysis : and except for accidents it follows
a direct line between the electrodes. Examination of the
spark with the revolving mirror shows that it is not a
continuous flame but a multitude of small sparks. The
little groups of oxygen and nitrogen are shaken apart by
the electromotive wave, and then combining chemically
burn violently. They are drawn together by cohesion
and combine with concussion, thus reproducing the electro-
motive waves which follow the line of the spark, but they
also produce some electromotive waves radiating at right
angles to the spark line and these are induction rays.
The heat, and light, and actinic rays of the spark have
nothing to do with the electric induction rays: they occur
because the compound gas resulting from the combination
of the gases of air is a third more dense than air, and because
RAYS 235
the contraction of its molecules throws the aether associated
with them into vibrations that produce these various
rays. Among all the rays produced it is the induction
rays only that can be called electric rays emitted by the
spark.
Like all other rays of aether vibrations, these influence
rays have no more than a mechanical effect, but the effect
is in the main such as is sufficient to give the molecule
acted on a tendency to reproduce the same action that
started the wave : and that action is chemical combination.
The following are some examples.
A spark gap breaks down more easily when a spark
is discharged in its neighbourhood because of the action
of the induction aether waves on the air in the gap : which
air is affected in precisely the same way when it is exposed
to rays of ultra-violet light, or of X rays, or any other
actinic rays, because in all these cases, inductive or other-
wise, the molecules are given a tendency to chemical
combination.
If the ends of the wires from a Leyden jar are put near
each other, but not so close as to discharge the jar, and
another jar, near at hand, is discharged with a spark,
the first jar will also be discharged because the aether
vibrations set up by the discharge of the other jar, have
brought the air to a state in which it is more easily forced
into electrolytic action than it was before.
In that small arrangement called a coherer, which is a
glass tube with some loose filings in it, and which is used
in aerial telegraphy, the " heap of filings scarcely conducts
at all for want of cohesion among their coatings of con-
densed air. But conducts instantly if a spark occurs
within a few yards. The resisting films of air are broken
down by minute internal discharges in the powder. A tap
restores its nonconductiveness." Each filing has its coat
of condensed air, and each coat has its covering film which
236 RAYS
prevents the coats from mingling : and the films are broken
down by the ray of aether vibrations sent out by the spark,
and not by " minute internal discharges," and the coats
then mingle and form a continuous conductor with un-
interrupted electrolytic action.
We have had several times in other chapters besides
this to refer to the liquid air coating which probably is
adherent to all exposed surfaces ; in fact in our study this
coating has bulked largely; but it may be that the fact,
that the air coating has a containing skin, requires some
confirmation in the minds of those who have not had its
reality made clear to them by experiment. There is
probably no scientist who does not recognize the exist-
ence of both the liquid air coating and its skin, but these
have by most of them been persistently ignored, as they
are stumbling-blocks to advanced ideas and have a rudely
toxic effect on electrons and such like metaphysic nonenti-
ties. And because the scientist ignores them, the reviewer
knows them not, and we see nothing about their
beauties in the magazine articles written to instruct the
public.
Both the condensed air coat and its skin are beyond
microscopic examination, but condensed air is a liquid,
and we can easily show that another liquid, that is water,
has a skin.
There is a beautiful experiment that shows the existence
of the skin on water. The experiment is this. Put two
straight taps in the side of a cistern, one directly below the
other : the jets of water flowing from these taps will fall
in two different curves, and because the lower jet goes
further in a horizontal direction, the upper jet impinges
on it: it does not however join the lower jet but bounds
off it: their skins have prevented their joining. Now if
a stick of sealing-wax is electrified by rubbing even at
five feet away, the jets immediately join: because the rays
RAYS 237
of influence sent out by the wax have broken up the
cohesion of the molecules of the water-skins.
We can see the skin on water. If we pour some water
into a tumbler and put a spoon in it, and look up from
one side into the water, we shall see the under surface
of the water-skin shining like the brightest silver, and it is
perfectly opaque to sight : and the reflection of the immersed
part of the spoon is on this underside, and the part of the
spoon out of the water we cannot see. It is plain that
this points to a difference of shape of the surface molecules
to those which are under them. The surface molecule
has the same quantity of cohesive attraction towards its
own centre and towards its fellow molecules as any others
have, but while those in the body of the water are sur-
rounded on all sides by equally dense molecules, the surface
molecule has only air above it, which has little attraction
for it, and from losing attraction above it has some of
its own central attraction to spare, and for both of these
reasons its upper side is flattened. The water surface
therefore is composed, probably, of flattened molecules
approaching a platino -convex shape with hexagonal
outline, which cling together more strongly than those of
the rest of the water and so form a slightly toughened
skin.
It is this skin, assisted by intercohesion of the molecules,
that keeps raindrops and other drops in their spherical
form. Without the skin the drops in falling would at
once break up. Chemists, when they wish to add a liquid
drop by drop, use a tube with one end drawn out to a
fine point and with a hole in it, and if water be dropped
from such a tube it forms in globes round the point: now
if a stick of sealing-wax be excited near at hand its influ-
ence vibrations shatter the skin of the drop, and the water
then falls in a tiny thread the size of the aperture in the
glass the molecules are now only kept together by cohesion
238 RAYS
and the thread of water is soon broken up by its accelera-
tion of fall due to gravity.
It is reasonable to suppose that all fluid surface molecules
are flattened by their own cohesion when they are in con-
tact with less dense surfaces, and that the same distortion
happens when they meet denser surfaces on account of
the increased mutual cohesive force which the contact
occasions, and that it is on this account that they so
obstinately adhere to such surfaces and cannot be separated
from them except by heat or substitution, and in some
cases perhaps not entirely by these.
RAYS
CHAPTER XXXI
HERTZIAN RAYS
WE will now consider the Hertzian ray, which is composed
of induction waves intensified by oscillation. These rays
have been mixed up with light rays, magnetic attraction,
X rays, and electrolysis in gases, into a huge mountain of
puzzle, and it has brought forth that " ridiculus mus "
electron, a puny reversion to the emission of the ancients.
The Hertzian wave is not a wave of electricity. Mr.
Larmor says " the transmission of Hertzian waves through
pipes is a proof that they are not in any way electrical,"
and " they stand in the same relation to electricity that
radiant heat does to heat contained in matter." Both
the radiant heat ray and the radiant Hertzian ray are
vibrations of aether and nothing more.
The Hertzian wave is produced by the electric spark,
and for a continuance of the ray the spark must be con-
tinuously renewed. This may be done, as Hertz did it,
with an oscillating spark, or by blowing across a gap, or
in other ways, and that seemingly preferred for wireless
telegraphy is the ball oscillator of Righi, the more intense
action of which has made it possible to produce induction
vibrations sufficiently ample to carry across the Atlantic
under favourable circumstances.
The Hertzian ray owing to the oscillation of the spark
is much more penetrating than the ordinary induction
ray which can be stopped by a plate of metal, or even by
a sheet of wire-netting, and any object surrounded with
wire gauze is quite beyond their influence : but the Hertzian
239
240 RAYS
waves are with great difficulty prevented from access, as
they pass through the smallest crevice.
Hertz produced these waves in quantity and continu-
ously by sending the discharge of an induction coil through
an apparatus that he invented. This consists of two
conductors with a spark gap between. A convenient
form is two sheets of metal plate, fifteen inches square,
about a foot apart, upright and in a line with one another,
and each with a six -inch wire attached to the near side,
and ending in polished brass balls that nearly touch. This
Hertz called an oscillator from its action on the spark.
When the plates are sufficiently charged, the electricity
breaks down the air gap, and leaping across surcharges
the other plate: from this it is sent back again, and so by
continued crossing and recrossing a succession of sparks
is kept up with a rapidity of many millions in a second.
These sparks produce induction waves in the aether:
and the length of the wave produced depends on the
number of sparks in a second: and this number depends
on the size of the apparatus. In such an apparatus as
that here described, there would be about a hundred
million sparks in a second, and the length of the induced
wave would be about ten feet. As their rate of transmission
through the aether is the same as that of every other
gather wave, that is to say about 186,000 miles in a second,
if either their length is known, or their number in a second,
the other measure can be found by dividing the equivalent
of 186,000 miles in feet by the known number.
To detect the waves Hertz used a wire bent into a ring
with the ends nearly touching, and he named it a resonator.
When of the right . size and held in the proper position,
electricity is produced on the ring by the induction waves,
and sparks pass between the wire ends. Hertz had a
large sheet of metal set up at the end of his room to reflect
the waves, and by exploring with the resonator found
RAYS 241
nodal points of no vibration caused by the interference of
the direct and reflected waves: and the distance between
these nodes was half a wave length.
The waves can only be detected by the resonator when
it is held horizontally in the plane that passes at right
angles through the surfaces of the plates and through
their spark gap: and if held vertically to this plane it is
not acted on by the vibrations as they are polarized in this
plane. Wood has been found to have a selective absorption
for the vibrations according to the direction of its grain,
and they can be refracted by a prism of pitch. So we see
that these rays can be reflected, and refracted, and
diffracted, and in fact acted on in every way like other
aether rays, and that they therefore differ in no way from
the others except in their scales of length and frequency.
They are not electricity, but produce it on suitable material,
and in this action also they resemble other rays in that
some of their energy is always wasted even when the
material is the most suitable.
The Hertzian wave, like all other waves, radiates in
straight lines from its point of origin, but it differs from
most other aether waves in this, that the others spread in
every direction, while these are polarized in the plane
that was before mentioned, and spread in rings more or
less confined to that plane. And probably it is this
difference between them and ordinary induction waves
which are not polarized that makes the latter so very much
weaker. That the rays are thus polarized is sufficiently
proved by Hertz's experiments, but this point has been
the subject of special examination which has confirmed
the statement.
These rays, owing to the great length of the vibrations
have great penetrative power in the case of material on
which they have no action, but they act on metals, that is,
in their air skins and are stopped by them: and like all
16
242 RAYS
rays the further they go the weaker they become: and
those passing through air no doubt encounter material
on which they can act and waste their vibrations. So
the rays produced by Hertz's oscillator, not being originated
by any very strong force, do not carry far, about a hundred
feet being the limit so far obtained, and that with the aid
of a reflector.
Those rays which also are called Hertzian though not
produced directly by the electric spark and which are
used by Marconi in wireless telegraphy, are the longest
aether waves known, those preferred for use being about
s ix hundred feet long, but they can be made much longer
by retarding the oscillations and much shorter by hasten-
ing them, and the smallest yet produced have been made
with Righi's machine, in which the central spark acts in
oil, and from which waves a quarter of an inch long can
be sent out.
The Marconi waves, being produced by a very much
larger instrument than the Hertz oscillator, have an
amplitude that carries them much further. You will
find published descriptions of the instrument if you wish
to study them, but it would be much better to see the
instrument. The author has not seen an instrument
and does not care to describe what he has not seen : and
as for the descriptions that he has read, they do not appear
to him to err on the side of lucidity.
Apparently the main principle that is relied on, by the
manufacturers of the machines, to give success in aerial
telegraphy, is, that the more means you employ for doing
anything the more will be the result : oscillating discharges
are sent through many long wires arranged on frames at
the station, and their combined energy produces induction
waves of great amplitude and therefore of great carrying
power : and attempts at increase of power seem to take the
line of increase in the number of wires, though one would
RAYS 243
think that several other expedients might be tried, and
one might make some conjectural remarks about
this.
We know that induction waves are projected at right
angles to the surfaces producing them ; and that the Marconi
waves being induction waves, they are not made by the
alternating currents running along the wires, but by the
chemical combination of the molecules on the surfaces
of the wires which is set up by the electrolytic action of
the currents: and that the vibrations thus produced in
the aether are sent out by the wires, in consequence of the
shape of their surfaces, in all directions in the plane at
right angles to the wires. Now one would suppose there-
fore, that if a sheet of metal were used, and had the currents
run on to it from a multitude of points, so that the whole
surface was brought into action, that the effect would not
only be very much stronger than with the wires, but that
also the direction of the radiation could be controlled, in
the same way that the direction of the current is controlled,
by a disc-shaped anode in electrical experiments.
These long waves from the wires can be refracted and
reflected like the waves of heat and light, but with more
difficulty, as they have more penetrative power than the
shorter waves owing to their much greater size in compari-
son with the molecule, which they can pass without being
broken up, that is absorbed or reflected. Just in the same
way that a great sea wave will pass a boat, while ripples
that encounter it are broken up or reflected. " Sulphur
is opaque to light because it is composed of minute separate
crystals whose facets reflect light like powdered glass, but is
transparent to Hertzian waves as the crystals are very
small to the wave of that length. So the substance as
regards these radiations may be considered homogeneous."
This is Maxwell's explanation and it appears to be univers-
ally accepted.
244 RAYS
But the elementary molecules are all less than a twenty-
five millionth of an inch in diameter, and the average
wave of light is about a twenty-five thousandth of an inch
long. Why then do not the rays of light penetrate all
elementary substances ? Surely a thousand times the
breadth of the molecule should suffice if length of wave
is the only necessity. And yet the light rays penetrate
glass which is a mixture of large compound molecules,
and will not pass through iron with its small, simple
molecules. Cast-iron is decidedly crystalline, and so are
many transparent and opaque crystals of elements and of
compound salts: so the crystalline formation does not
seem to be the bar to transparency that Maxwell assumes
it to be, nor is length of wave the only reason for penetra-
tion of rays.
" Marconi signals could be read at 3,800 kilometres by
night, but only 1,300 by day." There is evidently a
lessening of propulsive force by day, that is a decrease
in the amplitude of the waves, so it is probable that the
falling off occurs at the wires. They might through the
heat of .the day become less tense: would this affect the
emission of waves of aether ? But this is guessing: and
Marconi has suggested that " the sunlight disperses the
negative charge on the antennae," that is dries off some of
the liquid air on the wires.
It is somewhat the fashion now in England, though not
on the Continent, to call all sorts of rays light rays. There
is no reason nor advantage so far as one can see in doing
this any more than there would be in calling them all
actinic, or heat, or electrical rays. A wolf met a -pig
and would have killed it, but the pig said, " This is Friday,
and flesh is forbidden on Friday." So the wolf drew back
and said, " Ah yes, well goodbye, Mr. Whatsyourname,"
RAYS 245
and all would have been well but for the silly vanity of
the pig, who would go 011 talking. " I am called," said
he, " by many names: swine, pig, grunter, and the Latins
call me porcus." " Porpoise !" said the wolf; " why that
is as good as fish !" So he fell on him and ate him. We
will not worry about the moral of this, but it is surely better
not to use words that do not apply. Most wheels have
radiant spokes, but because cart-wheels have wooden
spokes is no reason for calling the spokes of iron wheels,
wood spokes: and similarly it seems silly to couple the
terms, light and optics, with rays which give ho light and
do not affect our optics.
RAYS
CHAPTER XXXII
RONTGEN AND OTHER RAYS
WE will now consider some other rays.
When electricity is sent through a glass tube from which
air is being exhausted, it at first passes in sparks: then
when the molecules are brought by further relief of pressure
into a condition in which they are more ready to combine,
the electrolytic track of the current is shown along the
axis of the tube by a thin flexible red line : and with more
exhaustion and fewer molecules, the whole tube between
the electrodes is in action and filled with a glow. So far
as this the exhaustion has aided the combination of the
molecules, and the light produced by the red line and the
glow has been that of the longer red rays because of the
less amount of energy required for the combination: but
beyond this point the rays given off incline to blue, and
this is on account of the more violent contraction that the
expanded molecules suffer in combining and the sharper
vibrations thus imparted to the set her.
The waves called electrical, that is the conduction and
induction aether waves, when acting on material can produce
no other ray than the electrical, unless the material changes
the waves through changes in itself: it is not these waves
that give the light to the spark, or the effect on a photo-
graphic plate, or heat, but the reaction of the molecules
after being acted on by these waves. In his chart of vibra-
tions Professor Lebedeff shows an unexplored interval
between the shortest of the electrical waves and the longest
of the heat waves: and if, as we suppose, the electrical
246
RAYS 247
waves are due to molecular action on the aether outside
the molecules, and the waves of heat, light, and actinism,
to action on the aether within the molecules, it is probable
that the region will always remain a blank.
" When the termini of an excited Ruhmkorff coil are
in an exhausted tube, the tube is filled with luminosity,
and rays can be seen streaming from the kathode. The
rays do not seek the anode. Professor Crookes believes
that the impact of the molecules of the remaining gas,
on the phosphorescent substance, produces light."
There are in this instance emissions of rays from two
sources: one the stream from the kathode, and the other
from the surface of the glass tube.
The molecular stream of electrolytic conduction from
the kathode need not directly seek the anode, and by vary-
ing the shape of the kathode it may be projected in
different directions. When the kathode is made in the
shape of a flat plate, the stream is projected at right
angles from the face of the plate, and does not swerve
from that line. Lenard, hearing from Hertz that this
stream could pass through aluminium foil, put a small
window of aluminium a ten thousandth of an inch thick
in the end of a tube, and found that the kathode stream
passed through it and into the air outside for a distance
of nearly an inch. The phenomena inside the tube is
called kathode rays, and that outside Lenard rays : they
can both be deflected by a magnet: both excite lumin-
escence: affect a photographic plate: pass through
aluminium a hundredth of an inch thick and through
very thin copper: and discharge an electroscope. They
are both one and the same not rays at all, but moving
oxygen molecules.
This stream of oxygen molecules is more noticable
than that of the nitrogen molecules which moves in the
opposite direction, because the four nitrogen units receive
248 RAYS
among them only the same amount of impetus as is given
to one oxygen ; but nevertheless they do produce, by their
condensation on the kathode, a feeble light as we shall
presently see.
It is on account of this difference of impetus that a
similar action has been noticed when a flame is placed
between two oppositely electrified conductors. They set
up an electrolytic action in the flame which distorts it
into two wings inclined towards the electrodes, one round
and full but not much advanced towards the kathode,
and the other longer and pointed towards the anode: the
first caused by the ample flow of nitrogen and the other
by the stronger rush of oxygen.
This sort of thing can also be made to occur in electro-
lytic solutions, where with a strong discharge through
good conducting fluid, the liquid creeps from the kathode
to the anode, that is to say the dense oxygen has received
enough impetus to carry the fluid with it against the
opposite movement of the hydrogen, although this has
twice as many molecules. This is an effect that is not
seen in badly conducting liquids in which most of the
energy of the current is wasted in overcoming resistance
to change.
The mechanical movement of this material oxygen
stream has been shown by Professor Crookes by means
of a tube in which a paddle-wheel is made to run along
rails by the impact of the oxygen molecules on those of
its paddles that are uppermost and in the stream.
The oxygen molecules in tubes always leave the surface
of the kathode at a right angle to it, so they can be
focussed as though they were a ray by a saucer-shaped
kathode, and a scrap of platinum placed at their point
of meeting in the focus of the saucer may be made red-hot :
the crowding together of the molecules causes their action
to be much slower and more like ordinary open air
RAYS 249
condensation, and consequently when they are thus
crowded there are more heat vibrations sent out and fewer
light vibrations.
The kathode stream is no ray but a stream of material,
and the pale rays of light that come from this stream in
the tube are due to the electrolytic combination of molecules
of oxygen with nitrogen and metallic vapours.
When the oxygen molecules are discharged against
Lenard's little window, they condense to liquid on impact
with the aluminium,' pass through, and expand to gas on
the other side: and they are probably assisted in their
forward movement by the impetus of successive batches
of molecules. The stream passes through the aluminium
because it is porous : it leaks through between the aluminium
molecules and does not pass through them as rays do.
The much thinner film of a soap bubble stops the stream
because the bubble is not porous : and the stream is quickly
lost in air with which its molecules mix, restored to their
natural gaseous state. Lenard let the stream " from the
aluminium window pass into a tube five feet long which
was exhausted as much as possible. It passed in straight
lines along the tube and could be detected at the end.
He says therefore that the aether is their medium." If
a little tobacco smoke had been shot into the tube it would
have behaved in the same way: but would the aether have
been the medium of the tobacco smoke ?
The other rays that come from Crookes' tube have always
been confounded with the kathode stream of oxygen
molecules, but they are true rays and are due to the con-
densation of the oxygen molecules on the glass of the tube.
The kathode stream that produces this light can be turned
about by a magnet because it is a stream of molecules of
oxygen, but the light rays that leave the glass are not
250 RAYS
thus acted on, being aether waves. The molecules of the
oxygen stream are expanded by the rarefaction of the tube
and contract so violently on becoming liquid when they
condense on the glass, that they can produce only those
vibrations that belong to the ultra-violet and luminous
rays: they can therefore strongly excite phosphorescence
in suitable substances and do not excite much heat.
These are true rays, but they come neither from kathode
nor anode, but from the surface of the glass of the tube.
There is a limit of exhaustion beyond which conduction
ceases, and we might almost be inclined to say that it
was because of the separation of the molecules, but this
probably never happens, the molecules expand and fill
all the space as bubbles would do, and the reason for their
no longer conducting by electrolysis is that the electro-
motive wave is too weak to impel the enlarged molecules
across the increased distances occupied by them. The
cessation is certainly not due to want of gas, for just before
conduction stops there is still a considerable stream of
oxygen molecules impinging on the glass, and the removal
of a few more atmospheres pressure could not empty
the tube; and as to any of the theories of separation of
molecules, they are all based upon mechanically impossible
forces, and on movements that could not effect the separa-
tion, there is therefore no explanation that satisfies the
conditions except that given above.
When the exhaustion is pushed almost to the point of
nonconduction a ray is given out that was discovered by
Professor Rontgen and named by him the X ray. These
rays penetrate substances that are opaque to ordinary
light, the depth to which they can go depending principally
on the density of the substance, for which reason metals
are very opaque to them, and uranium the densest of metals,
RAYS 251
the most opaque: they penetrate below the surface into
all substances, and on account of this penetration they
cannot be reflected or refracted but are diffused. Neither
can they be polarized which is obvious, but also no sign
of interference has been discovered, the reason for which
is not at all so obvious. Being thus prevented from acting
like ordinary light, the measure of their vibrations has not
yet been found, but from the manner in which they are
produced by the exaggerated force of condensation of
the molecules, it is certain that their vibrations are smaller
than those of the ultra-violet found in the solar spectrum.
All this points to some peculiarity in the production of
these waves, and their subsequent action would in every
way be accounted for if the following theory were allowed:
which is that the rays are produced by single molecules
condensing separately on the glass and each producing
a single light vibration.
It is only when the tube is about to become noncon-
ductive that the X rays can be formed, which, according
to our ideas, is when the molecules are moved with difficulty
in electrolysis: when the oxygen molecules are at such a
distance from one another that they must condense
separately on the glass and produce single vibrations: and
when on contracting in condensation they must, owing
to their liberty from much of their intercohesion, produce
the greatest effect on the aether by their simultaneous
concussion of impact and condensation on the glass. The
want of interference and impossibility of polarization of
X rays directly point to such a single wave.
" Goldhammer says that they are very small waves of
ultra-violet light," and " waves very small in comparison
with surface particles would refuse reflection or polariza-
tion," but it is their penetration owing to their smallness
that occasions this refusal. " Jaumann thinks that they
are longitudinal light-rays," but this is pure guesswork
252 RAYS
unsupported by any faci, and it is difficult to understand
how an exciting particle can produce any but an ordinary
vibration.
Rontgen rays are actinic but not at all luminous. They
act on photographic plates, and all of us have probably
seen photographs of our own or some one else's hands,
with a light shadow for the flesh, dark shadows for the bones,
and perhaps an image of a ring like an ink spot: showing
how the density determines the transparency. And this
is the usual rule, but the rays in some instances behave
in quite an unexpected manner. They will go through
" several inches of wood, but are cut off by an ordinary
pane of glass," and yet diamond is perfectly transparent
to them. We are so accustomed some of us at any rate
to consider density and hardness as synonymous, that we
would at once say that diamond was denser than glass;
but density depends on atomic weight and glass is about
three times as dense as diamond, and in consequence is
more obstructive to these rays, though this does not
account for all the difference in their action. Wood
being, for the most part, a compound of water and carbon,
is but a little more than half as dense as diamond.
The quick diffusion of the Rontgen rays is shown by a
precaution that has to be taken in using them for photog-
raphy. The object must be put close to the photographic
plate: even then a ring or other such opaque object, shows
t<he diffusion of the rays by the haziness of the edges of
its picture. High electromotive force is always needed for
good work because without strong force the action does
not reach the point at which these particular rays are
propagated.
The density of the glass and the transparency of the
diamond teach us one or two things. That transparency
to a ray depends on the action of the molecules: that the
rays pass through the molecules and do not wriggle through
RAYS 253
between them: also that the molecules are all and always
in touch except under very extraordinary circumstances,
for if this were not the case, all substances would be equally
transparent to all rays.
In the discharge in tubes, the rays made by the kathode
stream of oxygen molecules are easily seen even when a
small force is employed, but the anode stream of nitrogen,
on account of its feebler action, makes hardly any dis-
tinguishable ray, and this has led to the belief that there
are no positive ions, as they are called. But with certain
devices they can be made sufficiently visible, although for
the reasons stated, they are always much less noticeable
than those of the negatively produced stream.
If a plate with a hole in it is used as kathode, in a moder-
ately exhausted tube, the impetus of the nitrogen molecules
from the anode makes them pass backwards through the
kathode aperture and they mark their course by sending
out a blue ray. If the ordinary imperf orate kathode
plate is examined it will be seen that the same blue glow
of nitrogen radiates from its edges on every side. And the
same colour effect is produced if the oxygen stream is
directed on a negatively electrified spiral or piece of wire
gauze: the oxygen molecules cannot pass through as they
are taken up by the wire, but the nitrogen molecules
leave the wire and they are recognized by their blue ray.
But besides this, if these nitrogen molecules reach th&
surface of the glass, they produce by their condensation
on it, a fluorescence that is weaker than that caused by
the oxygen molecules, and which therefore gives a ray
with colour tint lower in the spectral scale and easily
distinguishable from that made by the condensing oxygen :
thus with soda glass, their condensation gives the lower
vibrations of a dull orange instead of the higher brilliant
254 RAYS
green given by the oxygen. These nitrogen -produced
rays are called dia-kathodic, or Goldstein's rays.
Wiedmann's rays are not sufficiently understood to be
categorically placed, but they are produced by alternating
discharge in a Crookes' tube, and seem to be vagrant
Crookes' rays.
Flammarion says in his book " Thunder and Lightning,"
that pictures have been imprinted on the skin by some sort
of rays emitted by the lightning flash. If these pictures
had been printed on the outer dress they would have been
somewhat convincing of the idea, but when it comes to
a print under a woman's stays or petticoats, it seems more
probable that it is due to contusion and not to rays. A
wound or a hard blow will often cut off some of the small
surface veins from the circulation, and they quickly become
black from congealed blood in them and show on the skin
like pictures of trees with ramifying branches, and an
ordinary bruise may colour the skin, so as to make a patch
which a lively imagination might convert into the image
of a cow or anything else. Very few persons would have
the chance of seeing the mark if it was on a woman's
breast or elsewhere, and those who did would make the
most of it, and like the story of the three crows, the de-
scription would grow from branching lines to a full branched
tree, or from a brown patch to a brown cow.
This finishes our examination of the rays that are called
electric, and in no case has it seemed necessary to invent
any fresh movements, or any weird phrases, or any words
more difficult of understanding than electrolysis and
contraction: and as these have sufficed to explain every
other phase of electricity we ought to be satisfied. Many
other rays, which are not our care just now, are originated
in various ways, but no doubt have the same proximate
RAYS 255
cause as the so-called electric rays, that is to say contrac
tion: for what can radiant light or heat do if it falls on a
diamond or some luminous paint, more than by its vibra-
tions expand the molecules in some manner, while their
recovery from this excited condition is what causes the
set her vibrations, that the substance afterwards gives out:
and the same must be the answer in every case, radium
inclusive: not necessarily a return of the molecules to a
former state, but a contraction from some cause.
There is no such thing as a self -illuminating ray. Every
ray, every vibration, every movement, is produced through
material and reacts on material, and can have no existence
without material. Scientists are constantly saying this
in one form or another, and as constantly seem to affirm
the contrary.
ATMOSPHERIC ELECTRICITY
CHAPTER XXXIII
ATMOSPHERIC ELECTRICITY
WE have so far studied electricity in the laboratory, let
us now study its action in nature and see if any of its
natural phenomena show any points that disagree with the
conclusions that we have arrived at.
They say that there is generally some electricity in the
air. ' The atmosphere is positively electrified under a
clear sky to as much as 1,400 volts per yard in height/'
The amount given is certainly a maximum, for generally
observations show, at the height at which they are usually
taken, an amount averaging about four volts positive.
Still fourteen hundred have apparently been found and it
seems a great deal, but as it requires twenty thousand
volts to produce a spark half an inch long, it is nothing
compared with the pressure, or tension, or potential,
which must be contained in a thunder-cloud: and the
tension in the air must at times be even greater than the
amount named, so much so that though very rarely
a flash has come from a blue sky, and an occurrence of this
has lately been reported.
The potential increases with height, but less rapidly
in the higher air than near the ground, and probably there
is none above the limit of cloud.
Not much attention has been given to this subject of
atmospheric electricity, and what has been done, has
mostly been done with the desire to find out whether such
observation would be of use in weather forecasting, it
having been supposed that falls of hail, rain, or snow were
preceded by negative electrification. But for this purpose
256
ATMOSPHERIC ELECTRICITY 257
it has been found that the observations are of no value,
as forty-five per cent, of the falls come with positive
electrification, and in the fifty-five negative cases, the
change to negative often comes with the storm, and in
both cases, positive and negative, the indications are
often remarkable for their want of indication. Besides
the changes and intensities are quite local: one place may
have a high potential, while another place three miles off
may have scarce any : on one side of a town there may be
enormous changes of potential from hour to hour and
even from minute to minute, while on the other side the
record may be a nearly straight line. The utmost, there-
fore, that can be said is, that " during fine weather the
upper air is almost always positive, but during broken
weather and after rain it fluctuates, and is more often
negative than positive," and that " before and after the
passage of a storm-cloud, the air is remarkably free from
electricity."
In storm}- weather the ordinary induction of the measur-
ing machine is entirely effaced by the action produced by
the strongly opposed inductions of the earth and clouds,
and the machine usually at such times shows negative
electricity, as much as two hundred negative having been
recorded: but this cannot be called the electricity of the
air, but is the induced electricity of the machine by the
influence of the earth or clouds, and the air when tested
after the clouds have passed away may be quite free
from electricity. During the continuance of a storm the
fluctuations are great, sudden, and continuous, and a
lightning flash, or a fall of rain often changes the sign,
and may for a few moments remove absolutely all sign
of electrification.
Observations for electricity in the air must be made in
the open: "there is none to be found under trees, in
houses, or even in enclosed places such as courts." There
17
258 ATMOSPHERIC ELECTRICITY
have been many modes used for collecting, such as kites,
flags, poles horizontal and upright, pointed rods with a
flame or smouldering substance at top, water dropping,
and so forth. A simple plan has been described by Mr.
C. E. Benham: a calico flag, with hemmed edges, two feet
by two and a half, is fastened to a flag pole, the end carry-
ing the flag being separated from the larger piece forming
the handle by a rod of vulcanite eight inches long. The
flag is put out of an upper window : touched with an earth
conductor: and rolled up by means of the handle: then
when brought in its electric charge can be measured by
an electroscope. The charge on the flag is produced by
induced conduction from the earth and not by conduction
from the air, and is of the opposite sign to that of the
electricity of the air. By rolling up the flag the charge
is prevented from escaping, which it otherwise would do
from the edges: and as it collects on the outside of the
roll, it is much intensified, and its action on the electroscope
is so much the stronger, and this must be allowed for if
the electricity in the air is to be estimated.
Only a small quantity of electricity can be collected
with such small means, but with apparatus sufficiently
large, great quantities may be gathered even at ordinary
times, and Mr. Crosse, in 1840, had some miles of insulated
wire exposed in the air, supported by poles from the tops
of the highest trees in his grounds, and with the electricity
collected from the air, could produce great sparks twenty
times in a minute that exploded with the report of a cannon.
When this sort of thing is done the business requires the
extremest precautions. Even with a kite and a single
wire line " flashes ten feet long and an inch in diameter
have been given off from a charged conductor ' ' : and
Professor Richmann, at St. Petersburgh, was killed in
1753, through going too near his apparatus: the room
was wrecked, the doors blown away, and the house
ATMOSPHERIC ELECTRICITY 259
shaken with the discharge. This, however, was a case in
which the apparatus was charged by a cloud, as a most
terrific peal of thunder preceded the flash from the
apparatus.
The various methods employed show the electrification
at the moment of observation, and as the potential often
changes very quickly, may give a quite wrong estimate of
the state of the air. To obtain a continuous record
Franklin set up an insulated metallic rod at one end of
his roof and attached a chime of bells to it which gave
notice of the state of the atmospheric electricity, but if
a lasting record is wanted, photography must be coupled
with some such instrument as the Kelvin water dropper.
This instrument is the most approved, but it is clumsy, and
where portability is wanted the burning fuse is to be
preferred. In either case the original charge carried by
the point is carried off by the smoke or dropping water
and the electricity of the air substituted, and the deflections
of the electrometer needle, connected with the apparatus,
measure the potentials at the smoking or dropping point
from moment to moment.
It is a pity that observations should have been made
only at low altitudes at least accepted observations
those made on mountain-tops have their own particular
conditions, and those made with kites do not seem to be
acceptable because they do not show enough electricity
in the upper air, and their deficit from what is estimated
theoretically is laid down to loss on the way from want
of insulation. It is very desirable to find whether there
is any electricity in the air above the limit of water vapour,
for if there is it can only be due to dust.
There have been one or two theories evolved regarding
atmospheric electricity, and all the old books are unani-
mously agreed in giving evaporation as the cause, and
this theory appears to have been proposed and accepted
260 ATMOSPHERIC ELECTRICITY
without any thought of experimental proof. But " atmo-
spheric electricity is not caused by evaporation," for many
and exhaustive experiments have since been made to try
to prove that evaporation is in some way the cause, because
it would so simply explain the presence of electricity in
the air and clouds, but every result has only been an
added proof that evaporation and electricity have nothing
to do with one another. However, it is very probable
that " increase of potential is caused by the condensation
of water vapour rising from the sea " or from anywhere
else. Evaporation is expansion and separation of molecules,
neither of which motions can tend to conduction, or
convection, or increase of potential, while condensation
would certainly increase the potential of acquired electricity.
" Atmospheric electricity is due to condensation of
water and to influence of ultra-violet rays ": and " atmo-
spheric electricity is not caused by evaporation. But
the friction of particles of water, and of dust, cause it."
Our present-day philosophers are chary of giving an opinion
about this matter, which indeed cannot interest them
much: they are not outdoor students, but laboratory
essayists, and simple science gives them no pleasure. So
we can gain but few ideas regarding the origin of this
electricity from books, and the extracts given are all that
have been found after some search. Nevertheless, atmo-
spheric electricity is an interesting subject, as it is not an
isolated phenomenon, but appears to be the main source
of the electricity of the clouds and of all the meteorological
occurrences that are connected with them.
Everyone seems agreed that water in some way or other
has to do with the electricity in the air, but there are facts
that decidedly oppose this idea. Conduction from the
atmosphere charges the explorer, but there is always
more electricity shown by the instrument when the air
is dry, and it appears that moisture is against electrical
ATMOSPHERIC ELECTRICITY 261
intensity, for if we examine the records, we find that the
dry and dusty times are the most favourable and that
the water only comes into play when it is condensing on
the dust to form raindrops.
Haze and fog lower the potential because they prevent
the dust from rising: clouds lower the potential because
they collect the dust to form their charges.
There can be no doubt that the electricity in the air is
carried by the dust in the air: there is nothing else in the
air that can be charged with electricity.
The earth is constantly at work chemically combining its
molecules of materials, and consequently constantly produc-
ing electricity. Most of this disappears at once owing to the
mutual cancellation of the two unseparated electricities:
but on the surface nature may provide means to separate
them. The damper parts are the more active chemically,
and are the anode in the arrangement, and the dryer
parts are the kathode: and the winds can separate the
dryer parts and with the buoyant assistance of the water-
vapour carry up this positively charged dust, and so leave
the earth with an equal negative charge which cannot
be cancelled except by a lightning flash, or by rain charged
with electricity. ' The atmosphere is almost always
positive," indeed, the negative electrification of the air in
fine weather has been so seldom observed, that we may
question whether it may not have been due to some un-
observed circumstance other than the natural state of the
air that on these few occasions made it so. In stormy
weather the fluctuations of the two electricities are plainly
due to the counter inductions of earth and cloud, and have
no relation to any charges in the air.
At Ithaca, in the United States, there were two observing
stations less than a mile apart, at which the records on
a fine day were repeatedly found to differ greatly both in
potential and in variation. At the lower station the record
262 ATMOSPHERIC ELECTRICITY
would be, for instance, a nearly straight line at 250 volts:
while at the upper station it varied between 1,000 and
1,700 volts, with great changes at short intervals. There
is no way in which we can account for this, except by
supposing that the one station was in a sheltered place
where the air was quiet,while the other had stronger winds,
from height and exposure, and gusts of dust and smoke.
And there are other instances from which it is evident
that it is the dust that carries the electricity, for, inde-
pendent of any locality, it has been found that strong
winds produce strong atmospheric charging, which can
only be by raising the dust: that there is less electricity
with height because there is less dust: that the air is clear
of electricity before and after a storm because the dust
has been gathered to the clouds along with the water
vapour: and there are no thunderstorms in wet winter
but only in dusty summer.
The dust is carried up from the earth by the winds
of course, but the upward streams of water -vapour also
do some of the work of raising it, and also in some cases,
when the vapour is changed to water in globules, some of
the work of preventing it from rising, as our fogs dis-
agreeably teach us. According to Quetelet, the air in
fine weather is about thirteen times as strongly electrified
in winter as it is in summer. This is due, besides the in-
crease of smoke, to the condensation of the water vapour
so much more quickly and so much nearer the earth in
winter, so that the dust and smoke from winter fires are
thus prevented from rising and have to form a denser
stratum near the earth. It is the smoke, without doubt>
however, that for the most part occasions the increase of
electrification recorded in winter, for the observations
on which the record is based have been made in populous
places and at no great height above the ground : so probably
observations made in open country or on a clear hilltop would
show that naturally dusty summer had the greater potential.
ATMOSPHERIC ELECTRICITY 263
There are two daily maxima in some places where
observations have been made, the first about two hours
after sunrise and the other after sunset, the latter being
the more marked. Possibly the first represents the
warming into activity in dust production of the town
fires, and the other the depression of the active dust zone
by vapour condensation due to evening cold. In other
places there is a single maximum at night.
We see in all the instances we have collected and they
have been made as diverse as possible to illustrate the
subject thoroughly that the electricity is connected with
the dust, and not with' the water in the air; and that the
air has nothing to do with it except as regards a possible
action of the ultra-violet sun rays, about which we have
no evidence as yet. And with regard to these rays, it
is not plain how any action that they could set up, could
charge the air with one sort of electricity only : for positive
is never produced without an equal quantity of negative,
and as there is no apparatus for parting them in the air,
they would immediately cancel one another if produced:
and also their production is, so far as we know, impossible,
as there is no known chemical combination of the air
due to these rays. Besides this, there seems to be no other
plausible idea as to any available source for atmospheric
electricity but " induction from the earth," but how the
earth should become negatively electrified, whereby alone
it could positively induct the air, is a puzzle for which no
explanation is offered. In fact, both these theories are
merely guesswork, and can stand no examination.
It appears, therefore, that in atmospheric electricity
neither the air is charged, nor the water -vapour mixed
with the air, but that the excited condition depends on
the dust carried by the air and which has become charged
by electrolytic action on the surface of the earth.
THE AURORA
CHAPTER XXXIV
DESCRIPTIVE
THERE have been many theories brought forth regarding
the origin of the aurora, and the most distinctly different
are given below with the principal objections to them.
The zodiacal light. This at its nearest is two million
miles away from the earth, and it is on the daylight side,
while auroras occur on the night side.
Ferruginous cosmic dust taking fire as it falls into the
atmosphere. Absence of the aurora at the equator is
against this.
Light reflected from ice-fields, or from ice particles in
the air. As the greater part of the auroral light is not
polarized this is impossible.
Phosphorescence or fluorescence of some substance
part of the ice particles in the air, the spectrum of the
aurora having a bright greenish-yellow line which is not
known to belong to any known substance. Neither has
such a substance been found in ice.
Electricity, because the auroral light resembles the
luminosity produced in rarefied air by the electric current
in tubes. Electricity probably has some connection with
the aurora, but as the aurora is seen close to the earth the
rarefied air of tubes has nothing to do with it.
Streams of positive electricity from the equator, flowing
in the upper air like Sowerby's wind currents, and dipping
towards the earth at the maximum auroral zone, and
creating disturbances with the earth's negative electricity.
There are no electrical disturbances associated with the
aurora at that zone.
264
THE AURORA 265
Pressure of the aether. " The sun and the planets are
hastening towards Hercules, and the earth describes a
spiral ellipse, or to put it better, an elliptic spiral, in which
the northern hemisphere always takes the lead: the aether
is supposed, therefore, to be compressed at this part and
rarefied at the southern hemisphere: and if the condensed
aether has positive electrical potential to the rarefied
aether, then the north pole will be negatively electrified
and the south pole positively, with maximum in September
and minimum in March." This is in no way in agreement
with the times of the auroras, which have in mean latitudes
two maxima, in spring and autumn, verging into one
midwinter maximum in high latitudes. And observations
of the moon show no sign of condensation or rarefaction
of the aether, though her course is at times faster than ours.
Also the hastening towards Hercules is mythical and
negatived by the spectroscope.
Sun spots, the physicists' universal providers, have, of
course, many votaries, and the latest ideas are that the
variolated sun either shoots out electrons or a rain of
electrified carbon -dust to produce the aurora. These
small things surely have not backs broad enough to bear
all that is put on them. ' The photosphere of the sun
contains large quantities of glowing carbon," and " this
carbon will emit corpuscles until the resultant charge left
on the sun exerts an electrostatic force great enough to
prevent further emission: any local elevation of tempera-
ture would then cause a stream of corpuscles to leave the
sun. When corpuscles pass through gas with high velocity
they make it luminous, and Arrhenius has explained many
of the periodic peculiarities of the Aurora borealis by the
supposition that corpuscles from the sun . . . stream
through the upper regions of the atmosphere." He might
have added that this also accounts for the dark colour
of the Africans who must, near the equator, receive more
266 THE AURORA
pelting from the sooty atoms than we who live further
north. But how then would he account for there being
no Aurora equatorialis ? And as for glowing carbon
in the sun, there is none, for carbon is vaporized at half
the heat of the sun.
Besides, how could carbon reach us from the sun ?
The earth could not attract it away from the much more
strongly attracting sun, and to suppose that material can
be shot clear of the sun's attraction is contrary to evidence.
The solar prominences are projected from the sun with
such violence that they have been seen to rise with a
speed of a hundred and twenty miles in a second, and yet
they can get no further from his surface than a few thousand
miles, and they are dragged back at the rate of nearly
two miles in a second, so strong is the sun's gravitational
attraction. It took three years for the earth to draw back
to it the dust from Krakatoa, but the sun would clear its
atmosphere after the most stupendous eruption in two
days at the most. If the sun cannot drive away its lightest
material, hydrogen, it certainly cannot drive off its twelve
times heavier carbon vapour. Our little earth has sufficient
force of gravitation to prevent the escape of our atmosphere,
or of anything else leaving us, to far beyond the moon, and
we cannot believe that the sun, with many times stronger
force, which can control the earth at so many million
miles distance, can allow any atom of its substance to
leave it.
We will not consider these wild theories, but will gather
what evidence we can and try to decide from it, and not
make our statement viva voce from imagination as those
who have formulated the ideas above quoted seem to have
done: but the subject is a very difficult one, and we must
not be surprised if, after we have finished our search, we
are obliged to agree with the final word of the examiner,
who asked one of the most stupid of a lot of scholars up
THE AURORA 267
for examination, to explain the aurora. " I knew it
yesterday," said the scholar, " but the excitement of the
examination has put it out of my head, and I cannot
remember it to-day." " That is a pity," said the examiner,
" as no one else knows it."
The Royal Society has published the observations made
by the officers of the Discovery: and M. Angot has written
a volume on the Aurora for the International Scientific
Series, in which all the latest investigations are mentioned :
and from these, and out-of-door personal experiences,
which probably many of you have had, we should be able
to gather most of the instances that are known about the
phenomena. We must go through the details of the whole
subject without any omissions, though we may find at the
end that some of our notes are not pertinent to what we
are looking for, so we will begin with the light, and then go
on to the sound, shape, action, and so on of the aurora,
and lastly, collecting the salient points, happily we may
light upon what we want to know.
The light of the aurora is seldom strong enough to cast
a shadow, and, unless very brilliant, is overpowered by
that of the full moon. It is not polarized so long as it is
uncoloured, and is therefore not a reflected light but comes
from luminous material. " It is rich in ultra-violet rays,
and has a spectrum of a hundred lines ": it is therefore
gaseous. Seven of the lines agree, or nearly agree, with
the lines of burning air produced by lightning, so it is
probably due to a change in the material atmosphere.
People in the Orkneys, the Lapps, Finns, Greenlanders,
Indians of Hudson's Bay, several scientists, and personal
experience, are all in agreement as to there being a rustling
sound made by the aurora: and those scientists who have
not succeeded in hearing it, have failed to do so probably
through not being in a proper position, for it can only be
heard when the aurora passes overhead.
268 THE AURORA
The production of sound would also point to the material
origin of the aurora, but ice spiculae are generally associated
with the aurora in high latitudes, and they may make
the sound.
The aurora is presented in many forms. Sometimes
as a faint universal haze, or a few cloudy patches, and
illuminated cirrus are often mistaken for these : in fact, it
seems doubtful whether the so-called faint auroral lights
are not always thin cirrus. In temperate latitudes the
aurora usually shows as a glow on the horizon, and it may
be low and motionless, or it may be slightly pulsing so as
closely to resemble the light of a distant town on fire.
But in the far north it is more often seen as an arc, which
is not the segment of a circle like the rainbow, but depressed
in the middle, which has caused it to be described as
part of an ellipse, a mistake due to perspective: what we
see is one side of a ring such as could be cut from a cylinder,
which is suspended at but a small height and seen side
on, the remainder of the ring being below the horizon.
The ring does not surround the magnetic pole but appears
in places towards the interior of the auroral zone.
The arch may be an even band of light, or it may send
up streamers like a fiery crown: and the streamers seldom
continue long in one place, but dart up and down, now
here now there.
When the aurora shows this arch, the space enclosed
between it and the horizon is abnormally black. It was
called the gulf, or chasm, by the Greeks and Romans,
and what it is nobody seems to know, but it is not confined
to the aurora, as it is an optical phenomenon apparently
due to light, and it may be seen on the horizon under the
sun or a high full moon, showing as a dusky segment of
a disc, and if the sea gives the horizon, the segment caps
the band of reflected sunlight or moonlight. It has nothing
to do with aurora or electricity. In Lieutenant Shackleton's
THE AURORA 269
" Heart of the Antarctic," Vol. I., page 204, is a photo-
graphic illustration in which the dark space is plain to see.
Often in these colder regions the aurora passes overhead
in huge wavy ribbons, draped auroras as they are called,
which have bright and somewhat denned lower edges
which seem to send up streams of light whose fading ends
form the upper border without definition. Sometimes the
streamers radiate in a tent-like form from a dark central
patch near the zenith, but this is an effect of perspective,
and they are in reality quite parallel to each other. When
this is seen the observer is probably under the middle of a
coronal aurora that would appear as an arc to observers
outside it.
North of 60 in Western Europe, and of 45 in
Eastern America, auroras are, in their season, of
almost nightly occurrence: and they are not seen
in the equatorial zone between Southern Europe and the
equivalent latitude in the southern hemisphere. There
is a zone on which, in the north, they appear in maximum
frequency: its centre, or pole, is north of Greenland, and
its periphery roughly follows the arctic coastlines of
Siberia and North America, and dipping south of Greenland
and low over the Atlantic it touches the North Cape in
Norway. South of this line the general direction in which
auroras are seen is towards the auroral pole: but inside
the line the direction varies greatly.
The aurora is often associated with halos, cirrus cloud
bands, and with mist, and on several occasions a curious
hazy patch has been noticed where the aurora has dis-
appeared. Now these and the dipping of the maximum
line over the Atlantic, and its avoidance of continental
land, would lead one to suppose that water vapour, or
frozen water vapour had something to do with the aurora.
From the Discovery, most of the auroras were seen to
the east, from which point the prevailing winds blew.
270 THE AURORA
The light of the aurora is generally white, except when
it is draped, when it is usually coloured prismatically,
with the tints arranged red uppermost as in the rainbow?
though much fainter; and often there is no colour band
except the red. This would indicate that the action of
the ice spiculse with the aurora is 'merely prismatic, and
that it is through their feeble refraction that the colour
is produced, for " the colours of the aurora are paler in
pure air and stronger when it becomes foggy, and draperies
are only seen over open seas." This last may be true of
polar manifestations, but draped auroras are seen inland
in Canada.
The length of the streamers continually varies, shooting
up to twice the height at one time that they do at another.
Not shooting up as a flame does, but as a moving illumin-
ated vapour would do. The rays usually dart upwards,
but may go downwards, and they may, without change of
length, both rise and fall, and these go by the name of
the "merry dancers " in the Orkneys. In the stationary
lights the light waxes and wanes gently, and never faster
than twice in a second, looking exactly like a distant fire:
and in the arcs it passes in pulses here and there, or to and
fro along the arc.
The great auroral displays seen in Europe and elsewhere
in temperate regions, and which on occasions seem to have
had simultaneous action in the southern hemisphere, are
visible at the same time over immense areas of land, but
curiously no records are forthcoming of any of these
medium latitude displays as having been seen at sea:
and this is the more curious, as with the constant watch
kept on shipboard, they could not have been unnoticed,
and we should expect to have heard more about them
from sailors than from land observers.
The auroras of the north are essentially local: and if it
does so happen that one can be traced as seen successively
THE AURORA 271
at several places along an east and west line, it is found
that the time at which it appears is the same local time
at each place, though several hours of actual difference of
time has occurred: the aurora has passed along attached
as it were to that part of the heavens in which it is seen,
and yet it is not seen rising or setting: it comes, lasts for
a time, and fades away. These smaller auroras are those
seen at sea.
The night everywhere, and spring and autumn in the
temperate zones are times of maximum appearances,
but in high latitudes the season of the maximum is mid-
winter : as spring comes on the auroras are higher, and there
are none in summer anywhere.
The supposition that the height of the aurora is between
fifty and two million miles above the earth, is a scholastic
deduction which has nothing to do with fact, for they have
been seen and their light tested and its yellow line found
often enough when they have been plainly below the
clouds and occasionally when not more than fifty feet
above the ground: indeed, Lemstroem once found himself
in the midst of an aurora, with the yellow line showing
in his spectroscope from all directions round him . In
the Discovery record we find, " a band of stratus cloud
in south, altitude 10, with aurora streamers behind
it," and " auroras are torn by storms," and both
storms and stratus clouds are very lowly things. Every
observation in which comparison with material objects
has been possible, confirms personal experience to show
that the aurora is lower in the atmosphere than cloud.
Anyone who is accustomed to study nature out of doors
artist, naturalist, sportsman, sailor and who has happened
to have been in the Gulf of St. Lawrence in the late autumn,
will probably have seen the draped aurora, and if he has
given the matter a thought would say, that the lower
margin of the rays was not more than twice the height of
272 THE AURORA
the ship's mast above him. Their advance from the
distance has the aspect of movement along a low level,
and the very excellent pictures in the Discovery report
give this same idea of want of height very distinctly.
Why then should such enormous distances be given
as the heights of the auroras seen in England and on the
Continent ?
At sunset we are sometimes charmed with a fine glow of
colour, and occasionally rosy rays rise above the point
on the horizon behind which the sun has set: and faintly
similar to these is the appearance of the auroras that are
seen in these latitudes. But in what way is it possible
to measure the heights of these displays ?
And, besides, there is no certainty that two persons,
even when standing near one another, see the same aurora
any more than they see the same rainbow. The rays ?
when they are coloured, are produced by refraction, and
then certainly every man sees them according to his
standing place. On one occasion two parties were stationed
three miles apart to take the angular height of the aurora :
one party signalled to the other to take the green ray:
but the other party saw no green ray. But even the
uncoloured light is perhaps seen in different positions
by different observers: and in the case of the uncoloured
aurora appearing on an east and west line at the same
local time at every place, this must have been so, and no
angular measurement taken at any two of these places
as it passed would have been of any use in determining
its height. Also lately, some photographs have been taken
on a north and south line, at identical times, of passing
auroras, and they differ in a way that does not seem to
be accounted for by mere perspective. Altogether it
would seem that every man sees his own aurora, and that
the only way of finding the height is by comparison with
material objects.
THE AURORA 273
The grand auroras in mean latitudes are accompanied
by great electrical and magnetical disturbances on the
earth. " Telluric currents which are produced by electro-
lytic action in the earth and which, when strong, disturb
magnetic and electrical arrangements, stopping telegraph
work by currents through the wires, and setting compasses
vibrating have been found to occur with great auroras."
This quotation seems to include more personal opinion
than description of fact. Chemical action produces
electrolysis, and it is difficult to understand how a sudden
outburst of chemical activity, lasting but an hour or two,
can be confined to a particular latitudinal zone of a
Continent without any of the action happening north or
south of the zone. However this may be, the disturbance
is not simultaneous with, but precedent to the aurora,
which seems to be produced by the disturbance, not the
disturbance by the aurora. If this compels us to ascribe
these auroras to electricity in the earth, it still leaves
vis free to choose how the auroras result from the
electricity.
The magnetic storms on the earth have recently been
ascribed to electrons discharged from the sun, which, for
some unexplained reason, do not continue their course
to the earth, but turn off through the upper air in currents
towards the poles, setting up as they travel, currents of
opposite electricity in the " same direction " in the earth's
crust. Such disturbances would increase the atmospheric
potential gradient, between the upper air and the earth,
enormously, but nothing of the sort has ever been observed,
though carefully looked for during these magnetic storms:
and if such an overhead current of electricity were set up,
the current produced in the earth would run in the opposite
direction to it, not with it.
No observer in polar regions has been able to find any
connection between magnetism and the aurora, although
18
274 THE AURORA
the magnetic perturbations in those regions are extra-
ordinarily frequent and intense. What is called a magnetic
storm in mean latitudes deviates the needle three degrees
at the very most: while in "American arctic regions
eight or ten degrees are not uncommon, and 20 40'
has been observed " with no aurora.
Neither has there been any manifestation of electricity
on the earth ever observed during arctic or antarctic
auroral displays.
The light of the aurora may be produced in any one of
three ways by the various action of cohesion, but one or
other of these it must be, whatever the primary originating
cause may have been.
By gaseous molecules combining as in lightning or the
will-o ' -the- wisp .
By gaseous and solid molecules combining as in phos-
phorescence.
By change in solid molecules as in fluorescence.
These are our notes, and we have to discover from them,
if we can, what produces the aurora. What force acts,
and what it acts on.
THE AURORA
CHAPTER XXXV
DEDUCTIONS
LET us now condense our notes and see what we have.
The light is self-luminous, therefore produced by material.
It is rich in ultra-violet rays, with a spectrum of a hundred
lines, and is therefore a gaseous production. And as there
are no other gases present, it must come from a combina-
tion or change in the gases of air, and perhaps of water
vapour. Three of the lines are identical with those of
burning air, and four almost: and concerning this last,
pressure change in the material through which the spectrum
is seen, may cause divergence of the lines, and very small
traces of impurity in a gas may cause considerable changes
in its spectrum, whether the impurity is chemically active
or not.
The greenish-yellow line, which is the strongest and
most, distinctive, is found to be due to krypton, and is not
found elsewhere except in the spectrum of the zodiacal
light. As krypton is more than five times as heavy as
oxygen it is not likely to form a stratum above our atmo-
sphere, and that is only a hundred and twenty miles thick,
so this forms a very decided objection to the assumed
enormous height of the aurora.
The air of the stones of the zodiacal nebula must be
frozen on their surfaces, and the change in the sun's rays
from actinic, with no light or colour, to rays of yellow
light, must be due to absorption of the rays by the frozen
air and its fluorescence in recovery from whatever change
the actinic rays may have produced in it. So, also, the
275
276 THE AURORA
yellow auroral light may be due to the fluorescence of
frozen krypton.
Auroras are not seen in the tropics, nor in summer
anywhere : they are higher in spring : and if seen on consecu-
tive nights, appear at the same time each night. Therefore
we may judge that a certain amount of cold is needed
to produce them. And cold produces contraction, that
is some change in the arrangement of the molecules, and
such changes produce the light of fluorescence.
We might conclude then that the aurora is produced by
the condensation of the gases of air in combination, and
that the curious hazy patches seen after the aurora has
passed away are, perhaps, clouds of vapour of condensed
gas: and that it is this condensation that produces the
yellow line.
The aurora has no constructural connection with water
vapour that can be traced, and yet water vapour seems
to favour the aurora. Therefore it may be that the
condensation and freezing of the water vapour may assist
an action in the air favourable to the production of the
aurora, and this is all that we can say on this point.
What force is it then that causes this action ? Is it
merely cohesion taking advantage of the loss of heat; or
is electricity also acting; or magnetism; or is it wind ?
In all regions cold is obviously a necessity, and is found
near the ground in the polar regions and higher in the
temperate. Electricity and magnetism are not connected
with the polar auroras. They appear more often in the
direction of prevailing winds. The aurora is torn by
storms: it is material, and its material is moved by the
wind: the auroral light waxes and. wanes as though some
pulsating force influenced it: no winds are steady and
unchanging, always they pulsate from moment to moment
and the lighter the wind the slower the pulsation: the
draped auroras sweep along as though they were carried
THE AURORA 277
by light winds, and they are local as though carried by
local wind currents: and the coronal auroras may be in
the position of descending Sower by wind currents.
So we will assume that the wind causes a disturbance
that assists some action of the molecules of the gases that
have been brought by loss of heat into a condition ready
for combination. Either a combination and consequent
contraction producing light due to chemical change, or
a recovery from some strain imposed by the cold and pro-
ducing fluorescent light due to molecular change. Further
than this we cannot go now.
So far we have been specially considering polar auroras
in which electricity has no hand : now let us pass to auroras
in temperate regions which are said to be due to electricity.
In the opinion of some, the electrical induction acting
on the rarefied air in a Geissler's tube exactly reproduces
the appearances seen in the great auroras, and they quote
this as a proof that all auroras are produced by electricity,
or are " a form of electricity " (a very loose expression)
and nothing else. But we can see plenty of lights produced
without electricity, and unless the yellow line has been
seen in the Geissler's tube, which is not so far as we know
the case, the discussion of the action in the tubes hardly
seems to apply.
There is certainly no rarefaction of air acting in polar
auroras, and there cannot be much in temperate zone
auroras : there is electrical disturbance along with the latter,
but entirely wanting in the former : so we will not change
our assumption as regards polar auroras on account of
appearances in the tubes.
But our deduction must be different as regards the
grand auroras from that regarding the polar, because the
premises are different. These stretch over vast areas,
and their light is steady, or slowly changing : not such as
would be occasioned by a gusty wind, but just what a
278 THE AURORA
continuous current of electrical induction should cause.
They are seen over land where electrical induction is
possible, and not over sea where there can be none: and
they follow electrical storms in calm weather. The only
conclusion that appears consequent on our data, is that
the induction vibrations induce, in the cold upper air,
that change that the wind assists in the polar auroras.
It is a pity that we cannot make a certain deduction
in either of these cases, but the above is all that the avail-
able evidence points to. When we know more and
there is certainly more to be discovered a more decided
judgment may be given. Hitherto, there has been a
great lack of system in the investigations that have been
made, with too much hard and fast adhesion to some
particular theory, and in the majority of records a careless
disregard which has confined the observations to " a fine
show to-night," or some such small talk. Let some of
the fine fellows who go to the dangerous polar regions
set down every detail that they can observe about these
beautiful phenomena, and then we may be able to decide
without theorizing that is guessing.
As to the colours of the light, their prismatic sequence
proves their optical causation. The white light has been
found to be unpolarized light produced by the aurora
itself: but the coloured light is this white light, or part
of it, refracted by ice crystals.
Before we leave this lecture let us consider a little more
fully the idea of tne emission of particles from the sun.
This is said to be possible owing to the minute division
of material, and electrons and corpuscles are names that
are given to these ultimate particles that are supposed
to be emitted. It is held, that the more divided material
becomes, the less action the natural forces have upon the
THE AURORA 279
particles, and that they have none at all on these infinitesi-
mal forms. That, in fact, the forces act less on the two
halves than on the whole piece.
However small the ultimate particles may be, our earth
is made of them and should therefore weigh nothing if the
above is true.
The idea of loss of action of gravitation on the more
minute particles seems to have arisen from an apparent
difference of its action on bodies in a medium: but this is
through misconception of two actions that of gravitation
which acts on the mass, and resistance in a medium which
acts on the surface of the mass.
A solid iron ball will sink fast in water, while a hollow iron
ball of the same outward size weighing but slightly more
than the water it displaces will sink slowly: the action
of gravitation on every atom of iron in either ball is the
same; and the pressure of the water on the two surfaces
is the same ; it is the difference of surface in proportion to
mass that makes the difference in the results. The dust
of Krakatoa took three years to settle, while the larger
pieces of the mountain fell, at once, into the sea close by:
the action of gravitation on every atom, in either case,
was the same, but the dust particles were composed of
so few atoms and had so -much more surface in proportion
to mass to oppose to the pressure of the air, that gravitation
took a longer time to overcome the resistance of the air.
In absolute vacuo, where there would be no opposing
medium, the two balls, and the dust, and the rocks, would
all fall together : a molecule would fall as fast as a mountain
because the action of gravity on every molecule in either
case would be identical and there would be no opposition
to its action.
Our material cannot leave the earth, because at our
distance from the sun, our gravitation is stronger than the
sun's: nor can the sun lose any material for a similar
280 THE AURORA
reason. A lighter material will rise above a heavier
because pressure being equal on equal surfaces there is
less gravitation of mass to be overcome in one case than
in the other: and nothing can escape into space because
there is no attraction in space of itself. To far beyond
the moon the force of gravitation towards the earth is
greater than any force of any member of our solar system
away from the earth, and therefore we hold our own:
but if it was not for our motion round the sun we should
be drawn into it is it possible then that the sun with
such tremendous power of attraction could send one
corpuscle towards us.
Another name that has been found for the ultimate
particle is prolith, which is considered to be the origin of
mineral substance.
Protoplasm we have, and we can see it, and handle it,
and consider it, if we can, as the origin of animal matter:
so why not undiscovered prolith as the origin of the
mineral. Prolith is called THE discovery of the age,
and is supposed to explain to us the origination of the uni-
verse. But neither real protoplasm, nor mythical prolith,
take us any further in the search for origination than that
old blank wall beyond which there must be nothing or
eternity.
No part of the infinitesimal idea is probable, provable,
or needful for real research, so why worry with useless
fancies while there is plenty of real work to be done ?
Give them a little time and all these fanciful ideas will be
put on the shelf along with phlogiston, latent heat, and
other follies of the past.
ST. ELMO'S FIRE
CHAPTER XXXVI
NATURAL GLOW DISCHARGE
AN electric glow discharge is sometimes produced by nature
unaided by science. St. Elmo's fire is an instance, and
the following description of it is an extract from the
" Memoirs of Admiral Forbin of the French Navy." " The
night suddenly became profoundly dark with terrible
thunder and lightning. We saw about the vessel more
than thirty St. Elmo's fires. Among them was one at
the top of the vane of the mainmast, more than a foot
and a half high. I sent a sailor to fetch it down. He
called out when he was at the top that it was hissing
like wet powder in burning. I told him to take off the
vane and bring it down, but when he lifted off the vane
the fire moved to the top of the mast and could not possibly
be removed. After remaining for some time it gradually
disappeared."
The most notable instance of St. Elmo's fire seen by
the author was in 1851. Near Cape Clear, the foremast
of the steamship was struck by lightning and carried
overboard, in a storm, leaving a jagged stump about five
feet high. This appeared to be blazing with blue flames
which the pouring rain could not put out, nor the stormy
wind drive away, and which did not burn the wood, but
which rose and fell with the fall and rise of the bows of the
vessel. How long it lasted he did not see as another
subject diverted his attention: one of the sailors had his
hand smashed and went to the doctor to have it seen to.
Two other poor fellows had lost their lives with the fall
of the mast.
281
282 ST. ELMO'S FIRE
Darnpier writes, " July, 1687, near Macao. An awful
gale from N.E., and dreadful thunder and lightning;
about four the storm abated and we saw a corpus-sant
at our main-topmast head, on the very top of the truck
of the spindle. This sight rejoiced our men exceedingly,
for the height of the storm is commonly over when the
corpus-sant is seen aloft, but when they are seen lying
on the deck, and creeping about the scuppers, it is generally
accounted a bad sign." It was a mistake on Dampier's
part to call those lights creeping about the deck corpus -
sants, for these only appear at the ultimate points nearest
the influencing clouds, and those creeping lights must have
been electric fire-balls.
The presence of St. Elmo's fire on the mastheads is
not, however, always a sign of danger past. " 1794.
January 9th, the East India ship Dover, in latitude 47
north, and longitude 22 west; a gale of wind with light-
ning and thunder. Sundry very large corpus-sants
appeared overhead, and settled on the spindles and seemed
like large torches. A flash of lightning struck the ship,
dismasted her, and stoved the deck, reversed the compasses
from north to south, and they wavered about and became
of no use."
The appearance of corpus-sants is not confined to ship-
board. Csesar saw it in the African War during " a
frightful storm with hail of uncommon size; the points
of the javelins of the fifth legion appeared all in a flame,
and shone with a spontaneous light."
Transactions of the Royal Society, 1774. " 1st March,
6 p.m., Mr. Nicholson, returning to Wakefield, saw
a storm approaching from N.W. ' I made haste homeward,
but observed a flame of light dancing on the ears of my
horse, and several others much brighter on the brass
ferrule of my stick. Five or six graziers overtook me.
They all had the same appearance, and one in particular,
ST. ELMO'S FIRE 283
who, when he arrived at an inn, called for a candle to
examine his horse's head, as it had been all on fire, and he
thought it must certainly be singed. In twenty minutes
it abated, and the clouds divided ... a light was said
to have appeared on Wakefield steeple.' '
The same sort of thing occurs sometimes to the mountain-
climber. Mr. Church in " Science " gives a description
of a display on Mount Rose in California. There is an
observatory on the hilltop, and in it a party of visitors
took shelter from a storm of snow and hail. When they
left the building, " every artificial projection on the summit
was giving forth a brush discharge of electricity. The
corners of the eaves of the observatory, the arrow of the
wind vane, the clips of the anemometer, each sent forth
his jet, while the high intake pipe of the precipitation
tank on the apex of the summit was outlined with dull
electric fire. Whenever our hands arose in the air, every
finger sent forth a vigorous flame, while an apple, partially
eaten, in the hand of Captain Brambila, sent forth two
jets where the bite left crescent points. This latter
phenomenon occurred, however, only when the apple was
raised above the head, and ceased when it was lowered,
so that the eating of the apple involved no visible eating
of flame."
Darwin, speaking of the effect of induced electricity
when in the Andes, says: "My flannel waistcoat when
rubbed in the dark appeared as if it had been washed
in phosphorus." Sometimes the feeling produced by
the escape of the electricity through the skin is disagreeable
and even painful: Saussure felt as if wasps were creeping
up his back and stinging him: and other travellers have
complained of more or less painful irritation.
St. Elmo's fire sometimes appears as a flame the size
of a man's head, but more often it is much smaller as
a flame, and most commonly it is merely a glow with
284 ST. ELMO'S FIRE
scarcely any extension into the air. Captain Fitzroy
says of it, in his book on the surveying cruise of the
Adventure and Beagle, that it resembles the light made by
" a piece of phosphorus or a glowworm, and not quite so
large as the flame of a candle."
It is usuaDy stated, in explanation of this phenomenon,
that a lightning flash is imminent, and that the electrical
stress is only prevented from violent rupture by the quiet
discharge thus given by the conductor. Certainly, so
far as experience goes, lightning seldom follows this display :
it may go before it, but when St. Elmo shows his light the
danger may be said to be over. Sailors have looked upon
it as a safeguard for ages: Jason on the Argo took it as
a sure sign of a prosperous voyage.
What it means is, that the air for some reason is more
than usually averse to electrolytic action, and refuses to
carry on the effect: the induced electricity on the earth
is trying to escape, but has to be content with getting
away in this slow manner, by changing its force to the work
of driving of the condensed air gases from the point, and
causing a chemical combination of some of the oxygen
and nitrogen. St. Elmo's fire is a brush discharge, and
it has been found in all brush discharges that have been
examined, that there are products of the combination of
oxygen and nitrogen in the discharge, and that it is these
chemical combinations that, for the most part, give the
light of the discharge.
The advance of a denser cloud may increase the force
of the glow, but there will be no flash unless the cloud
nearly touches or at any rate comes close: and the cloud
is emptying itself in the same manner from all its points.
The air will not act as conductor and neither the earth
nor the cloud can make it act, because most of the chemic-
ally active dust and the moisture particles, which alone
can convect electricity in the air and which would have
ST. ELMO'S FIRE 285
helped the action of the air, have gone to the clouds,
" Before and after the passage of a storm-cloud the air
is remarkably free from electricity," and if the air could
be examined during the passage of a storm, it would be
found to be just as free as it was before and after, but its
state at that time cannot be ascertained instrumentally,
as the instrument is charged by induction of the earth
and clouds. An increase in the distance between the clouds
and the earth would naturally act in the same way to
prevent conduction.
This fire, from all accounts, is specially associated with
strong winds and hail. Now, so far as personal observa-
tion goes, hail comes from high clouds, and wind drives
clouds away and raises them, and in both cases there is
distance between the influencing bodies which must
increase their difficulty of discharge by electrolytic conduc-
tion. But the charge in the cloud being considerable, its
influence is great, and causes a corresponding exertion
of influence on the earth beneath it, and in consequence
these brush discharges, which are called St. Elmo's fire,
are given off, from available points.
The apparition called ignis fatuus, will-o'-the-wisp, and
other names, though it very much resembles St. Elmo's
fire as it is usually seen, has nothing to do with electricity,
but it is a strange sight, so the following description,
taken from notes of one seen by the author in the Lushai
Hills in India, is worth recording.
The day after we stormed Koongnoong we occupied
the village, which was of nice clean and large houses
built on raised bamboo platforms, and that night I took
the rounds to relieve the man on duty. The sentry at
one end of the village had his post near by the cliff at
the edge of a pit about forty feet deep, with walls of
286 ST. ELMO'S FIRE
perpendicular rocks enclosing it in more than a semicircle :
there were shrubs and long grass growing on the ground
below which sloped gently to the open hillside, and the
place was no doubt a depositing place for cast-off rubbish
from the village. For a moment I thought that there
were people with lights below, and I said to the sentry,
who are those ? God knows, Sir, they are not men,
said he, and then I knew that they were Jack-o'-lanterns.
It was as though invisible ghosts waved ghosts of torches.
The lights had the shape of flames, broad not high, of a pale
blue and giving little light. They moved with every breath
of air, floating away and returning to their places again,
some on the grass and others on the tops of the bushes ; or
seeming to be blown out and to start somewhere else.
It is the bad air of that dirty place burning itself away,
said I to the sentry, and it seemed to cheer him up a bit,
but he was a Ghoorkha and I dare say had seen such things
before in his own hills. There were twenty or more of
the lights flickering about. This was written by the light
of a splendid full moon by which the smallest print might
have been read. We were at a height of over 5,500 feet.
FIREBALLS
CHAPTER XXXVII
NATURAL GLOW DISCHARGE
THE name fireball is given to several objects, including
meteors, an artillery shell, and an incendiary missile,
none of which have any connection with electricity, but
the phenomenon so named which we are now considering is
electric, and probably is produced in somewhat the same
manner as St. Elmo's fire. It is, however, of much rarer
occurrence: few persons have seen St. Elmo's fire, and
fewer have even heard of electric fireballs: and the author
thinks himself peculiarly favoured in that he has seen
two. To arrive at a decided opinion as to what they are
is not to be done even with the help of other descriptions,
for they have been so seldom seen, and then have passed
so quickly, that there has been no examination possible
of them, and as for conjectured theories based on mere
descriptions, any one person who knows anything about
electricity can make them pretty nearly as well as any
other. So far then as instruction in electricity goes, one
might pass them over, but they are such splendid objects
that it would be a pity not to record what one knows
about them, so we will therefore give them a chapter.
About the year 1844, a fireball was seen at Montreal,
Canada. The situation was as follows. The author was
in the open verandah, facing south, of a country house,
in front of which was a lawn about twenty-five yards
across, with large trees beyond. The fireball came from
the north-west and passed obliquely towards the south-
east : it bounded lightly across the lawn touching the grass
in two places, and striking the ground at the foot of one
287
288 FIREBALLS
of the trees, sank in, tearing open the turf and throwing
up a little earth as it did so : there was a slight dull sound
from the ground where the ball disappeared, but none before
that, either during its flight or on striking, and the grass
was not damaged where the ball touched the lawn. The
distance was not more than thirty yards from where the
ball came in sight to where it sank. The ball was glowing
white, the size of a large round football, its glow prevented
it from having any determinate outline. It seemed light
as a bubble and went no faster than a man would go when
taking a quiet walk. It was unfortunate that the origin
of this fireball could not be seen, but a greenhouse closed
the end of the verandah in the direction from which it
came. There was no rain, and it was a clear and quiet
summer afternoon.
The author saw another fireball in 1877 at Shillong in
the Khassia Hills in India. Its appearance was like that
above described except that it was decidedly yellowish
in colour. It appeared near the top of a small pine-tree
at about twelve feet above the ground: it came down the
side of the tree quite slowly taking full three seconds
to do so : it then entered the ground at the foot of the tree
and opened a furrow about fourteen feet long in a straight
line away from the tree. Its origin was apparently where
it was first seen on the tree, there was no previous sign
of it. The furrow in the ground was of an even depth
and breadth of about fifteen inches nearly to its end.
No sound was heard, but there was a strong wind blowing
which would no doubt have deadened slight sounds.
The soil at that place was peaty leaf mould about eighteen
inches deep, overlying a very hard red clay: the earth
was very wet, but not the clay except where its surface
touched the earth. The wind, which was blowing very
strongly, did not disturb the fireball in the least, but it
came down the lea-side of the tree. There was no rain.
FIREBALLS 289
These two fireballs were surrounded with a dazzling
glow such as we see round masses of white-hot metal, and
very much recalled such glowing masses except in the
sense of weight and heat that the metal conveys. These
seemed cold and as light as air, as if they could be blown
away like feathers, which was certainly not the case with
the second. Both of them appeared in the daylight
between four and five in the afternoon.
The following are some extracts from books:
" M. Colon, Vice-President of the Parisian Geological
Society, saw one of these singular meteors leisurely gliding
downwards along the bark of a poplar. It took at least
five or six minutes to reach the base of the tree, as if un-
able to overcome the resistance of the air : but on touching
the ground it rebounded with a wonderful rapidity, and
disappeared without exploding."
Royal Meteorological Society's Journal. Referring to
the line squall of February 8th, 1906. " Two well authen-
ticated cases of globe lightning occurred during the storm.
One occurred at Haver hill in Suffolk. Mr. R. Ruffer
supplied the following description. A ball of fire as
large as a cocoanut, leaving a trail behind it, struck the
mill about forty feet up, and ran down the bell-wire and
chain, melting the former and sending it on the white-
washed wall like electroplating. It set the links of the
chain together, so that great force was required to separate
them. I saw the fireball about the size of a large orange
on the chain about forty feet up the mill, about one and
a half yards from me. It stood still for a short time,
and then went down to the bottom floor and exploded
like a cannon when it came in contact with the ground.
This happened at 2.30 p.m. on February 8th. I was
surprised to find after the explosion that very little damage
had been done."
" December 7th, 1848. H.M.S. Rodney, seventy-four
19
290 FIREBALLS
guns, was struck with lightning in the Mediterranean:
the iron hoops of the masts were all broken and magnetized.
Fireballs, or corpus-sants, rolled about the deck, and the
men ran after them to throw them overboard. Four
men were killed/' These men, however, were killed by
the lightning and not by the fireballs.
A picnic party took refuge in a barn from a storm.
This was in June, 1826, in the Malvern Hills. " The
electric discharge appeared as a mass of fire rolling along
the hill towards the building in which the party had taken
shelter, and two young ladies were struck dead." This
may have been a fireball, or it may have been a streak of
lightning seen end on.
Fireballs often have the name but should not be con-
founded with globe lightning, or ball lightning as it is
variously called, that is, lightning discharged as a ball
from a cloud, and which is a thing that probably never
occurs, though every year we read descriptions of it.
Here is an instance. A professor was standing at a door
watching the approach of a storm: he saw a ball of fire
start from a cloud and strike the ground about fifteen
feet in front of him. Speaking of it afterwards to some
of his friends he described it as ball lightning. Some of
them who had seen the flash assured him that it had been
an ordinary streak of lightning. He had seen it end on.
In the extract from the Meteorological Society's Journal,
already given, it said that two cases of globe lightning
occurred in the storm of February the 8th, 1906. The
second was as described below by the Rev. Allan Coates
of Barsham Rectory near Beccles. "Between 2.15 and
2.30 p.m. I was sitting in my study, which faces west,
with my back to the window. I heard some rumbles
of thunder, and then a very brilliant flash of lightning
caused me to turn round and look out of the window.
Between this flash and the thunder I counted twelve or
FIREBALLS 291
thirteen. In about a minute it began to rain hard, and
I saw a very vivid flash of zigzag lightning from west-
north-west passing to north, and in the limited field of
vision between a tall cedar and a large clump of yew-trees
it seemed to be almost horizontal, slightly inclining down-
wards towards the north. The wind was then blowing
from the north-west, and it began to hail. I counted
five or six before the thunder came. Then almost immedi-
ately, in the north-west, there appeared a huge circle of
light, giving the impression of the heavens being opened,
most vivid, and in size, as far as one could judge, two or
three times the diameter of a setting sun. It appeared
just above the cedar in height, but not near it in distance
from me. At the same moment an appalling crash came
like the bursting of a big shell immediately overhead.
This was, I suppose, the moment at which the east end of
our church, a hundred yards from this house, was wrecked.
The circle of light was visible for some appreciable time.
The hail turned to snow and there was no more lightning."
His wife and daughter saw the flash like a great sun
which " seemed to travel over the house. If so, it would
also pass over the church, and coming from the north-
west .would naturally disappear in the south-east as the
gardener says."
'' My gardener, looking out of the stable-door facing
south-east, uses the same expression as I have just done,
viz., that the heavens seemed opened above him, and two
huge arms of yellow light seemed to come together and
joining strike the earth to the south-east. This might
have been what set on fire the farm at Brampton some
four miles south-east of this."
This was evidently a flash seen end on. The first flash
seen was nearly horizontal and so also was this one. It
divided into three branches after passing over the house,
one striking the church, and the other two converging
292 FIREBALLS
and perhaps striking the farm. The really curious thing
about these flashes is their avoidance of the ground directly
under the storm-cloud, and their running long horizontal
courses. It was raining hard so that it was not from want
of moisture of the earth underneath that the currents did
not go to it. The only conceivable reason is that they
followed the track of dust particles closing in to join the
cloud, such track offering a better conducting medium
than the air cleared of dust below the cloud.
The Times of 17th February, 1909, reprints the following
from its issue of the same date in 1809. "We have been
favoured with the perusal of a letter from on board the
Warren Hastings, recently launched at Portsmouth, and
now moored at the Mother bank, which states a singular
occurrence that took place on board that ship on the
14th instant, for the truth of which we can vouch ":
" The morning being fine, it was deemed necessary to
get up the topgallant masts, which occupied some hours.
About three o'clock in the afternoon the atmosphere was
overcast to the westward, and every appearance indicated
the approach of a violent storm. Several alert sailors
were sent aloft to strike the topgallant masts as speedily
as possible, but while lowering them the wind blew tre-
mendously, and the rain fell in torrents, accompanied by
heavy claps of thunder. In the midst of the confusion
occasioned by the storm, three distinct balls of fire were
emitted from the heavens; one of them fell into the main-
topmast cross-trees, killed a man on the spot, and set the
main-mast on fire, which continued to blaze for about
five minutes, and then went out. The seamen both aloft
and below were almost petrified with fear. At the first
moment of returning recollection, a few of the hands ran
up the shrouds to bring down their dead companion,
when the second ball struck one of them, and he fell, as
if shot by a camion, upon the guardiron in the top, from
FIREBALLS ' 293
which he bounded off into the cross- jack braces. Finding
that he still survived, he was relieved from his perilous
situation, and brought upon the deck with his amis much
shattered and burnt. This poor fellow was expected to
undergo immediate amputation, as the only means of
saving his life. The third ball came in contact with a
Chinese, killed him, and wounded the main-mast in several
places; the force of the air, from the velocity of the ball,
knocked down Mr. Lucas the chief mate, who fell below,
but was not much hurt. For some time after the storm
subsided, a nauseous, sulphureous smell continued on
board the ship."
This is plainly a case of ordinary lightning seen end on:
three flashes following each other on the same track to the
same mast. It is curious how these old-time people
likened all strange smells to sulphur fumes. King James
in his counterblast says that tobacco and that pit that is
bottomless have a similar sulphureous, horrible, stygian
smell: and here we have the same savour attributed to
ozone.
Many more instances could be given of so-called ball
lightning, but they would not illustrate the question more
clearly than those given: and anyone who desires further
information should read M. Flammarion's very interesting
book in which all sorts of lightning and effects occasioned
by and attributed to lightning are given, and he can exert
his ingenuity of mind in discriminating how much in the
stories is due to electricity, how much to other circum-
stances, and how much to lively imagination.
Mr. Alfred Hands believes that both fireballs and ball
lightning are due to imagination or delusion, and has
written to say so in the English Mechanic of the 13th
August, 1909, in which he gives five instances, two of
which are due to reflection from metal plates and one to
a small waterspout. He is, no doubt, right as to all
294 FIREBALLS
instances of globe lightning, but not to all instances of
fireballs. Some of these may have been instances of St.
Elmo's fire followed by lightning, but some have very
certainly been moving globes of light detached from solid
material.
It will be understood, from what has been described,
that there will always be some difficulty in arriving at a
precise knowledge of the constitution of fireballs, but this
much we assuredly know regarding them, and that is
that their light must be due to chemical combination, and
we may also say with certainty that it is a combination
of gases, and that the combining gases are the gases of
the air. And this points to what may prove to be the
explanation of the phenomenon: and, in fact, Professor
Righi has performed an experiment which appears to
confirm this idea. He passed a strong current of positive
electricity through a tube containing highly rarefied
nitrogen, and instead of the luminous glow that ordinarily
appears, he produced a patch of light that moved slowly
along the tube, one way or the other, according to the
strength of the current used.
This patch of light was certainly due to the combination
of gases in the tube at a point that marked the crest of
a wave of augmentation of chemical combination due to
the interference of electric influence aether vibrations.
Whether such an action can occur in the open air is a
question, but theoretically it would answer perfectly for
the production of fireballs. There is in these two pheno-
mena of the tube and the air, nothing that we know to
be in common except their lights the radiant vibrations
of aether that they project which can only be produced
in one and the same way: that is by the contraction of
molecules in combination: so beyond this we can only
theorize as to the identity of the causes that produce these
contractions.
FIREBALLS 295
Since writing the above the following has been published
in the Royal Meteorological Society's Journal for October,
1912, among descriptions of thunderstorms in July
and August of that year, by Spencer C. Russell. " 13th
July. Thunderstorm at 2.6 p.m. . . . During this storm
at 2.31 p.m. there was a vivid flash of fork lightning from
cloud to cloud immediately followed by the formation
of a round incandescent globular ball, about the size of
the full moon, bright white in colour, due south, which
remained visible about fifty-five seconds, and travelled
slowly at a considerable elevation, becoming lost in heavy
rain and cloud."
Also in the Bulletin of the Astronomical Society of France
ior October, 1911, there is an article on the caprices of
lightning, in which four instances of the occurrence of
fireballs are mentioned.
LIGHTNING
CHAPTER XXXVIII
PRODUCTION
WE will now try with the help of facts that we have
learned in the laboratory, and that we have seen in nature
to find out the history of lightning. And first as to its
production. To make the study thorough we must begin
with weather conditions.
When there is a change to rain coming on it happens in
two ways, which the gardener distinguishes as weather,
and thundery weather. There are lots of modifications,
but only these two fundamental courses. The first is
when we have rainy weather. There are cirrus clouds
in a pale sky: a draught of intermediate air blows under
them, and its vapour, being shaded from sunshine, con-
denses to cirrostratus : another layer forms under this
from a cross current, and as many as five or six layers
may be thus spread out, each augmented by vapour from
below, and rain may be falling from three of them before
the lowest is complete. This is how a rainy day originates,
and it may come with much wind or little, and end in a
simple downpour, or a cyclone, or a straight blow : but there
is no lightning. There seems to be no electricity in these
clouds, and if there is any it must be bound in each layer
by the influence of that which is in the layers above and
below. Of this sort are our winter storms. They are
bred from Atlantic vapours and exhibit no electricity.
Why?
The other way of change is when there is thundery
weather. To begin with, there have been several hot
296
LIGHTNING 297
days and the last is oppressive with a dull sky: in the
afternoon, when the sun's power lessens, the restraint
gives way: dusky patches gather in mid air and hurry to
join together from all sides, and a great heap of cloud is
formed, flat and dark below, and with a rounded brilliant
white top. It is several miles in area and perhaps a mile
high: and the sky above it is of a beautiful pure dark
blue, because all the vapour and the dust that was in the
air have gone to make the cloud. There is no wind with
this clout 1 except just below, for wind prevents its formation,
and if the wind below has any strength, it is only because
of the small gap between the cloud and the earth that
it has to pass through. Rosy lights of small discharges
may sometimes illumine the cloud momentarily as it
nears completion: then there is a dazzling flash, a terrific
peal of thunder, and a deluge of rain: but the rain was
formed before the flash. This is the type of our summer
storms, they are bred over the land and are full of electricity.
Again, why \
When we come to think over the processes that can
possibly lead to the formation of clouds and to their
charging with electricity, and try to pick out a material
and a process by which these things can be accomplished,
we at once say that it must be by water vapour and its
condensation: the cloud is most certainly formed of con-
densed water vapour, and the vapour, no doubt, rises
from the sea already charged with electricity, and the
cold in the higher regions of the air condenses the vapour
to cloud and the business is done. It is so simple an ex-
planation, so self-evideiit, and so little requiring of thought,
that we accept it at once without question or experimental
proof, just as the old scientists did, and on their authority
this explanation has ever since been taught in our schools,
and it is absolutely wrong.
Evaporated water has been proved by many careful
298 LIGHTNING
experiments to have no electricity, and the reason is that
when it rises in evaporation, it is an invisible gas made
up of separate molecules, and in this state it cannot be
electrified. Each vapour molecule consists of two atoms
of hydrogen and one of oxygen and the electric action
requires the interchange of the oxygen atom with a like
atom from another molecule, and this cannot be done as
long as the molecules are separate: but when the vapour
becomes in its second state visible through partly con-
densing, and we see it as cloud, it then can take on the
electric action, so that there is no difficulty about the
charging of the cloud after it has formed, provided the
electricity is somehow conveyed to it.
It is plain that the separate molecules of water vapour
can have no skins, so that in that condition they can join
together; but while floating in air they are kept separate
and single, by the restraint of heat, until they have gained
a height where the cold of the air reduces the effect of the
sun's rays so much that they can come together and con-
dense into the minute globes of water that form the clouds.
As these little globes are visible with the help of an ordinary
magnifying glass, they must contain millions of molecules :
and as they can remain in this state unchanged for a long
time, it is evident that they have arrived at a size when
their water skins are fully developed and capable of prevent-
ing any further joining together: and that therefore they
cannot after this form raindrops unless they have some
assistance.
Now, after eliminating evaporation, we have nothing to
fall back upon to electrify the cloud except the electrified
dust in the air, and which is carried with the water vapour
into the cloud. No action of friction of particles, or any
other means of electrical production, in the cloud, or in
the air, can make any change as there is no machinery
there for separating the two electricities that would be
LIGHTNING 299
thus produced: so it is the dust that charges the cloud
with the electricity that it has brought from the earth.
Besides electrifying the cloud, the dust also helps in
the formation of the raindrops, and the concentration of
the electricity. Lord Rayleigh discovered that " electrifi-
cation of water particles causes them to unite into larger
drops." The positive electricity on the surface of the
dust grains sends out influence vibrations that break up
the water skins of the globules: and they fly to the dust
grains, where they cohere, and thus drops too heavy for
the air to support are gradually formed, and they fall
together and join together till they make raindrops.
While this last combination is going on, the larger the
drop becomes the less surface it has in proportion for
the electricity to occupy, and, given an opportunity, the
charges will dart away. There is also on this account a
great accumulation of electricity in the lower part of the
cloud: it is all positive and it draws the equal quantity
of negative electricity that it left on the earth towards
that part of the earth's surface that is under the nearest
part of the cloud: and the positive being the easier to
move, as soon as it is strong enough to force its passage,
it seeks the earth in a flash.
Electric conduction, whether positive or negative, con-
sists of a force and an action caused by the force. In
order for the force to pass from one point to another it
must be strong enough to cause a change all along the line
between the two points. The change is caused by the
force, but the force cannot get across without the help of
the change. It is like a man running up a ladder; he does
all the work, but he could not get along without the rungs.
When, therefore, the electric force in a cloud has accumu-
lated to such an amount that its influence vibrations can
strain the air to chemical action along a slender track
to the earth, it passes down and its track is shown by a
300 LIGHTNING
streak of light. We call it an 'electric flash, and quite
wrongly, for what we see is the chemical combination of
the oxygen and nitrogen of the air which burn uvidly
together. Electricity has neither light nor heat of itself:
it is the chemical action of the materials that it u^os that
makes the light and heat.
Some things are known as good conductors of el octricity
copper for instance and a good-sized copper lightning
rod will carry off any charge of electricity that nature can
produce without giving any indication that it has done
so: because condensed air is apparently the very best of
conductors, and copper interferes hardly at all with its
work: but if the rod is broken, though the gap may be
of the narrowest, the badly conducting air in it would
offer so much resistance that enough luv; would be
developed by its combustion to fuse the ends of the rod,
the chemical action producing both heat and Ught.
Writers have declared that it is an inexplicable mystery
how a flash a mile long can be produced by a cloud. The
way for the flash is helped, no doubt, by the water vapour
in the air, water being a very much better conductor than
air, but for the greater part it is the air that conducts
the force, and the resistance of air to conduction is strong.
Still all the electricity of the cloud tends towards its lower
part, either carried there by raindrops, or drawn by the
attraction of the earth's opposite charge, and there are
several cubic miles of cloud to gather from, and that surely
ought to supply enough to force the passage : at any rate
it is enough to produce the long sparks we see.
It has been found that the stronger the charge of electric-
ity, the more easily it breaks do\yn the opposition of the
air. A force of ten thousand volts will make a spark in
air an eighth of an inch long: but a force of twenty
LIGHTNING 301
thousand volts will make a spark half an inch long. That
is to say, that with twice the power the spark is made four
times as long. So probably the force needed for a lightning
stroke is much less than is generally calculated.
The volt is a measure of electricity that represents about
five-sevenths of the force of a standard cell in which is
a zinc plate about half an inch long by a quarter inch
broad. The volt is five-sevenths of the force produced
in a second by the chemical action on this plate. Let us
suppose that one volt of the force that this little plate
produces can electrify some measure of dust in the cloud:
nobody knows how much, but let us be liberal and say
that it is the dust in ten thousand cubic feet of cloud.
Then from a block of cloud twenty thousand times as big
we should get a spark half an inch long: and as there are
736 such blocks in a cubic mile, each cubic mile of cloud
would give us, according to the geometrical proportion of
four times as long for twice the voltage, a flash more than
three miles long.
The discharge of a cloud may happen in other ways
besides through a flash of lightning. Rain would do it if
the whole cloud changed to rain: each drop would carry a
small charge. " Smoke discharges atmospheric electricity
slowly but surely and thoroughly. The German peasants
have a traditionary saying, that when a storm comes, as
much smoke as possible should be made in the stove.
Professor Schuster, quoting from statistics, shows that
in 1,000 cases of lightning stroke, '3 are factory chimneys,
and 14*8 are churches, and mills with no fires burning."
The smoke-dust evidently forms a channel for discharge,
probably by convection. Smoke would thus prevent
lightning stroke in a storm, but under a clear sky it helps
with other dust to electrify the atmosphere.
302 LIGHTNING
Perhaps, also, smoke acts sometimes as a conductor
by assisting the conduction of the air, for there have been
cases where the smoke certainly appears to have induced
the lightning to pass down the chimney into a house.
In the Himalayas the people will not burn rhododendron
wood, as they say it brings thunder and lightning. This
tree, stunted and crooked, is often the only one to be seen
on the grass-covered tops of the hills, and former hunters
and herdsmen using such places would have used the
wood for their fires, and the smoke from them might have
brought down a flash, which not finding earth easily in
the fire, destroyed the men near it, and one or two such
incidents would send the men to lower parts to camp
where they would find other fuel, and there the smoke
would bring them no harm, and so by deduction they
would get their idea about rhododendron wood. On the
side of the hill the stress of the electric charges would be
much less than at the top where the different charges of
the earth and cloud are drawn to approach and cancel
each other. In the Andes, as Darwin tells us, almost
everything that was touched gave off sparks, and the hair
of his dog's back stood up and crackled. Cats, they say,
cannot live in those places, it would be difficult to say
why, but this, fortunately, is not our immediate concern.
One can understand that the tops of the hills should
often be struck on account of the stress between the
charges of the earth and cloud, but besides, there are
particular localities which are constantly struck, either
on account of their position, or apparently because of
some mineral contained in them.
There was once a house whose situation brought it
ruin. It was built on the spur of a hill because from thence
it commanded a magnificent view. Surrounded by high
hills on three sides, the spur was between two valleys
which joined into one below it, and this pointed in the
LIGHTNING 303
direction from which storms usually came. This house
was twice struck and twice repaired : it was struck a third
time while it was occupied, on account of its remoteness,
by a man with another man's wife: they were killed and
the house burnt down: and then it was left to ruin. This
is a case of what Pliny would have called judicial lightning.
The presence of minerals certainly appears to attract
lightning, and several instances might be given of hills,
which were known to hold iron ore, being often struck:
they are, however, in places that are not generally known,
and naming them would make few persons any the wiser,
but the following are three good examples of the attraction
due to iron in use.
A company of Ghoorkhas was sent to help in quelling
a petty disturbance. The locality was a plateau about six
thousand feet above the sea, and the men were housed in
a long hut of bamboos and thatch, and their rifles were
ranged along the back of the hut: they were struck with
lightning and fourteen men (if memory serves) were killed.
A flash came down a chimney, assisted apparently by
the smoke as conductor to the iron grate, and from thence
it darted to an iron bedstead, killing the son of the woman
who lay sick in it on its way: it then passed down one of
the further legs of the bedstead through the floor to metal
in the ground floor, and so away. The woman felt
nothing.
There were three clerks working in a temporary office
in India, the walls of the office were of wattle and dab
(reeds, bamboo, and mud) and the roof of corrugated
iron. A storm came on, and before any rain fell the place
was struck with lightning. After the flash the iron sheets
rattled in such a peculiar way, that the men were frightened
and one of them ran out through the door and was killed
as he passed under the eaves. Probably when the roof
was struck a great part of the electricity passed on from
304 LIGHTNING
one of the corners into the ground, but enough was left
to charge it heavily, and the sheets of iron shook in trying
to repel each other, and as there was no rain there were
no trickles of water to carry away the charge, and the walls
were too dry to do so: so when the man passed out with
his head within four inches of the eaves, the electricity
used his body as a conductor and killed him. When the
other two men ran to pick him up they felt nothing, and
the rattling had ceased.
LIGHTNING
CHAPTER XXXIX
EFFECT
WHEN a series of oscillating surges is set up between two
conductors, we may conclude that they give alternate
positive and negative sparks, and that with each oscillation
the conveying molecules on and between the conductors
are moved one step in electrolysis: that is, that there is
one molecular exchange and no more with each spark:
and that the interchange is always in the same direction
as regards the molecules of oxygen and nitrogen relatively.
And we may also conclude that in a simple discharge,
where the receiving body is in free connection with the
earth, that there is no oscillation and that the spark has
merely a single action on the molecules. It is not meant
by this that a spark uses only one single string of molecules
in its passage between the electrodes, for a spark of per-
ceptible size probably uses thousands of strings, but that
there is only one interchange of components along every
one of the strings, and that there is no further electrolytic
movement. That, in fact, in the case of lightning, the
tension on the earth being instantly relieved by the flash,
that there is no surge of negative electricity towards the
cloud. If we make the discharge between the coatings
of a Leyden jar difficult by interposing some resistance,
we prevent oscillation. The discharge through the air
between the cloud and the earth is very difficult, so there
is no oscillation, and no emission of negative electricity
from the earth. Certainly every flash in a multiple
stroke, no matter how fast they follow the first flash from
305 20
306 LIGHTNING
the cloud, is of the same sort as the first flash and there is
no observable alternation: and multiple flashes could
scarcely occur if the electricity in the cloud were cancelled
by a counter charge from the earth.
In the laboratory we have seen that the spark in every
case starts from the positive terminal, except, perhaps,
when a negatively charged and insulated body is dis-
charged into an uncharged insulated body, and similarly
in nature the spark always leaves the positive body. A
few cases have been cited of negatively charged clouds,
but there have been no authentic cases of lightning from
earth to cloud, and though photographs have been pub-
lished which are supposed to show such flashes, they have
been (so far as those seen by the author) evidently flashes
between clouds in which the emitting cloud is further
away and perspective makes the horizontal flash seem to
rise to the receiving cloud more nearly overhead. There-
fore we will take it that the cloud from which lightning
comes to earth is positively charged, and its flashes are
simple and without oscillating return.
Negative clouds, however, may very naturally occur,
because the smaller clouds would be charged negatively
by induction from the larger ones, and their electricity
would be cancelled by flashes from the large clouds, and
this is what occurs in some thunderstorms when there is
much lightning but none that comes to the earth. These
storms generally occur at night and they move slowly in
a cyclonic spiral and are accompanied by little wind.
When a lightning flash uses the material of a man, or
animal, or plant, to convey it, the molecules of the object
struck are simply moved one minute step in electrolysis:
but as that means the momentary disorganization of every
particle in the track of the current, it means death, and
LIGHTNING 307
there is never recovery from such a stroke. The after
condition of the body through which lightning has passed
confirms this. There is a very small mark of burning
on the skin at the point of entry, but after that the current
has spread and used the softer tissues and the blood for
its conduction, and these are so disorganized that putre-
faction soon sets in. The harder parts have been avoided
as being bad -conductors, so that the ligaments and harder
muscles have only suffered from return shock and have
by this been violently contracted, and remaining so the
body is at once rigid.
We constantly hear of persons who have been struck
by lightning and who have recovered, but they have
suffered from return shock and not from the lightning.
The whole of the ground under a storm-cloud is strained
with opposite electricity to that of the cloud, especially
towards that point which is under the nearest part of the
cloud, and any person or thing standing in the strained
area shares the strain: every molecule is electrolytically
strained to meet the discharge, and when the discharge
takes place and the strain ceases, the sudden relief gives
a severe shock which may be fatal. So persons to whom
this occurs say that they have been struck with lightning
though they have been away from the spot where the
lightning fell.
The sudden cessation of the strain in a person who is
near enough to the centre to be seriously affected, nearly
always produces insensibility, with temporary loss of the
use of the limbs, or of some of the senses, or some other
affections which pass away after a time. The name counter-
stroke has also been given to this shock which is merely
the release from strain and return to natural action of
the molecules.
When the wet clothes are used by the current as con-
ductors, the sudden expansion caused by electrolysis
308 LIGHTNING
often throws them in fragments from the body. These
cases are mostly fatal : not from the passage of the electricity
through the clothes, but because of the strong counter-
stroke in the body. The following, though it was a case
of shock from an electric wire, will serve as an example.
A stoker got on the coal in his tender (contrary to regula-
tions in the electrification area) and so brought his head
near the contact wire, and received a shock which made
him unconscious for several hours, and put him out of
working order for many days. The day was wet and so
were his clothes: a hole was burnt in his cap, his hair and
eyebrows were singed and his face slightly burnt, a large
hole was burnt in his sock, and a hole in his boot. The
electricity passed through his wet hair, his collar which
was turned up, and his wet clothes and did him little
outward damage, but it affected the whole of his body
with responsive return shock, and moderately disorganized
the whole. Had the current gone through him it would
have produced the same amount of return shock, and one
direct line of absolute destruction which would have killed
him.
The surface of the skin sometimes seems to be used as
the conductor, and seems to be variously acted on by the
current, depilation being one of its freaks, but it is curious
that in the cases recorded of skin actibn there are fewer
fatal cases than in any other kind of stroke : but the records
are very imperfect owing to want of discrimination, and
probably these are not cases of lightning stroke, but of
return shock where the strain has not only been strong
enough to raise the hairs, but also to dislodge them.
There has lately been a case of lightning stroke in this
neighbourhood when four persons took shelter beside a
heap of hurdles from an exceptionally heavy burst of rain :
they were all thrown down and three of them were struck
with the lightning which divided into three branches and
LIGHTNING 309
used their very wet clothes and skins as conductors.
One of them was killed: his face was scorched, his clothes
torn, and his boots and gaiters burst, and one of the gaiters
was thrown to some distance: two others, a woman and
a girl, were more or less scorched about the legs and their
clothes torn and burnt : the fourth, a man, was only thrown
down and recovered quickly. The flash that did this work
must have been a very small one from a cloud trailing near the
ground, otherwise the return shock must have killed all four.
Being under any sort of shelter seems to be a protection
from return shock, and the very slightest interposition
of nonconducting material will prevent the passage of
electricity provided it has a better alternative route, so
that a person would be quite safe who lifted a live wire
with a folded newspaper or the crook of his walking-stick
if dry: and bedclothes are a protection judging from the
case mentioned of the woman in bed whose son was killed.
*****
The thunder comes from the sudden expansion produced
by the combustion of the air in the track of the flash: the
rumbling is due to echoes between earth and cloud and
between cloud and cloud. When next you have an
opportunity of hearing the thunder from a near at hand
flash, listen to it attentively. The noise comes crash,
crash : that is the sound from the air where the bolt struck
near us, followed closely by the sound from the air where
the lightning left the cloud: then after a pause you will
hear the rumble of the echoes.
The light of the flash does not come from the " electric
fluid " as is the common idea, but from the combustion
of the air in the track of the flash. The molecules of air
combine so violently in return from the action of the
enormous electromotive force that has been used in forcing
the passage, that they produce intense vibrations of every
sort from ultra-violet to induction, and consequently the
310 LIGHTNING
light, which is fortunately all that we are sensible of, is
very intense and acts accordingly.
When we look at a stained -glass window we see all its
divisions and its leaden tracery quite distinctly, and if
we look at the clear sky at night we see the stars as distinct
spots of light; but if we photograph either the stars or
the window, we get blurred outlines because of the diffused
action of the light on the plate. It is the reverse of this
however with the effect of the lightning flash, for in this
case the eye is the more defective instrument and takes
the worse picture, for the flash appears to us when distant
as a broad luminous stripe, and if it is near, the action is
spread over so great a part of the- retina, that a blaze is
seen " as if the heavens were opened." The photqgraph
owing to the instantaneous duration of the flash gives
sharply margined lines, but even these are too broad,
for probably no spark of lightning is of more than the
thickness of a telegraph-wire, for whenever the point of
entry of a flash into a human body has been examined,
it has been found to have made but a small mark that
would be covered by a threepenny-bit, and that mark
represents the area over which the action is spread by the
resistance of the skin.
The cross sectional area of the condensed air covering
on the largest lightning rod, which conveys the flash to
earth without the slightest sign of disturbance, is certainly
very much smaller than the cross sectional area of the air
space which we have given as that occupied by the flash
in coming from the clouds, but the condensed air-coat
contains fourteen hundred times the amount of material
that an equal measure of air does: and the air offers enor-
mously more resistance to electrolysis than the liquid
air does: both of which show why the electricity' prefers a
conductor, even though it is a long one, to pushing its
way through air or any other resisting medium.
ANIMAL ELECTRICITY
CHAPTER XL
INSTANCES AND DEDUCTIONS
THERE are a few instances in nature of animal electricity
with what may be called a definite purpose, as in the
torpedo and gymnotus, which are provided with galvanic
apparatus for defence and attack. The explanation of
the working of the powers of these creatures has not yet
been satisfactorily given, and how it is that they manage
not to shock themselves is simply a marvel.
In the gymnotus the apparatus is fourfold. There
are two pairs of long bodies : one pair along the back of the
tail, and the other pair along the anal fin, all just under
the skin : each of the bodies is divided by long partitions
and with very numerous small cross divisions so close
as to almost touch, and making about two hundred and
forty little cells in every inch, the little spaces between
the divisions being filled with a jelly-like fluid: the exterior
surface of all these bodies that next the skin is positive.
They very much remind one of voltaic piles, but are
different in their working, as in these the electrolytic
movement is from side to side and not in the direction of
the length as in the voltaic pile.
The eel can produce a positive current which is projected
through the water to a distance of two or three feet in
every direction. Water is necessary for the full communi-
cation of the shock, which in air is very feeble. The follow-
ing little tales will illustrate this. Some one somewhere
in South America caught a gymnotus with the intention
of sending it to England, but it was killed in the water in
which it was kept by a water-rat. Those who have seen
311
312 ANIMAL ELECTRICITY
this latter interesting and disagreeable creature swimming
under water, will have seen that it appears to be clothed
with silver. It is the air which remains entangled in the
creature's hair that gives it this shiny look, and this
air-coat acted as armour of proof against the electrical
shocks of the gymnotus. The second story is about a
torpedo, but the electricity of both creatures travels in
the same way. One day a small Hindoo went fishing:
he had no rod, being clever enough to play his line with
his fingers after the manner of his forefathers: almost as
soon as he threw in his hook he had a fish on and after a
little play drew out a small torpedo: the moment the fish
landed on the sand the little boy fell on his back with a
cry: the fish, which had been hooked in the back, had
sent him a shock along the wetted line.
It has been stated that the eel's electricity is an outcome
of " vitality." This is an explanation of the lucus a non
lucendo order. We require vitality to eat and digest our
food, but the grinding could be better done by machinery
and the digesting equally well done in a chemical labora-
tory: and similarly the eel can certainly at its will cause
or cease the action of its batteries, but this is probably
all that vitality has to do with it and the apparatus could
very possibly be made and worked by us if we knew what
materials were needed for its construction and excitation.
What the materials are and how they are worked is what
we want to know.
Now if one end of a piece of raw flesh is heated, its ends
give a feeble electric current : they have different potentials
because a greater chemical action is going on at one end
than at the other, and there is electrolytic action in the
juices between the ends. It is, we suppose, some similar
action that produces the electricity in the gymnotus.
There is an air-bladder extending the whole length of the
fish : it has been found that the air in the bladders of other
ANIMAL ELECTRICITY 313
fishes that have been examined contains a large quantity
of oxygen which has been occluded in some way by the
bladders, sometimes to as much as eighty per cent.: by
compressing the bladder the inner sides of the batteries
of the gymnotus would be excited by transfused oxygen
and an outward positive current established at once.
This is reasoning by sorites and may or may not be true.
Themistocles said: "My little son rules his mother, his
mother rules me, I rule the Athenians, the Athenians
rule Greece, Greece rules Europe, and Europe rules the
world, therefore my little son rules the world." This
according to argument should be true, but like many
arguments soritic, mat hematic, or metaphysic, its end is
plainly wrong, and so may ours be, but we will continue
to believe in it till we hear of a better. The jelly-like
fluid of the cells, like all animal fluids, no doubt can act
as an electrolyte, but it would add to our confidence in
our theory if, on examination, it proved to be a good
electrolyte.
The arrangement of the batteries in the torpedo is
different from that of the gymnotus. They are two masses
of hexagonal cells, one on each side of the head and touch-
ing the skin above and below: the interior of these cells
is divided by numerous partitions piled over one another
from bottom to top, and with liquid jelly between them.
There is no air bladder in this case to supply oxygen,
but there is an enormous nerve and blood supply. Those
who believe in the electrical action of the nerves cite this
as a proof of their theory, but in reality the office of the
nerves is to incite the capillaries to increased transmission
of oxygenated blood, and this, if it excites the upper
surfaces of the small partitions to action on the jelly-like
fluid, must create a current which would give positive
electricity from the upper side of the battery and negative
from the lower, which is in fact what is observed. " The
314 ANIMAL ELECTRICITY
upper surface gives positive and the under surface negative
electricity."
It is curious that the torpedo can electrify the water to
a distance of two or three feet round it. One would
suppose that a circuit would be formed in the water close
to the fish, and that beyond this there would be no action.
Cavendish made an imitation torpedo to experiment with
and was astonished to find that the water gave him a
shock. He charged his torpedo with positive electricity
and the current passed to the ground through the water
and the legs of the table on which his tank rested until
he put in his hand, when his body gave an easier and there -
fore preferable route. His apparatus was in this essenti-
ally different from the living fish which makes its own
electricity and therefore must send out both positive
and negative currents.
There is a family of fishes named Malepterurus, found
in the Nile and other African rivers, which is electrical.
It grows to four feet and has a soft skin. The electric
organ " covers the whole body but is thickest on the
abdomen and consists of rhomboidal cells which contain
a rather firm gelatinous substance. The electric nerve
is a single enormously strong primitive fibre branched
in the electric organ." When excited by the fish the organ
produces a succession of small shocks sixty to a hundred
and twenty in a minute. Du Bois Raymond found that
Malepterurus was but very slightly affected by induction
currents passed through the waters of its tub though they
were strong enough to stun and even kill other fishes.
Further experiment should be made with this easily
obtainable fish.
Humboldt has left us a lively description of the method
that was employed to catch some of the gymnoti for his
examination. How a lot of broken-down mules and
rozinantes were collected from the farms and driven into
ANIMAL ELECTRICITY 315
the marsh: and how the fish laid themselves out to shock
the beasts, two of which fell in the water and were drowned :
and how the fishes having presently become exhausted of
their power, were some of them safely speared and brought
to shore. Since then no traveller in Surinam has ever
seen such a hunt, nor been able to find out that it has ever
been the practice, and relying on this negative evidence
detractors have said that Humboldt is relating a made-up
story that was told him to impose upon him, thereby
making him out to be at once a prodigious liar and a
gullible fool. Those persons cannot have read the original
description or else they are very wanting in discernment,
otherwise they would certainly see that he is telling of
what he saw, and besides this, that this mode of capture
was not in use and probably had never been used before,
but that it was the result of a happy thought on the part
of Humboldt's host, who had been fruitlessly engaged for
a week in trying to get him the fish. There are some
persons who take pleasure in adverse criticism, adopting
it seemingly as the mission of their lives and delighting
in the chance of bespattering great reputations. Theirs
" is one easy artifice, that seldom has been known to
miss to snarl at all things right or wrong."
The lights of the glowworm, firefly, and other insects,
have sometimes been attributed to electricity though
no sort of apparatus for electric action has been discovered.
The light is a phosphorescent light, quite cold, and is
probably produced by the combination of oxygen with
some emission from the insect, in the same manner as
the glow of phosphorus is produced by the combination
of oxygen with the vapour from the surface of the phos-
phorus. For some reason the vapour and oxygen have
a very strong chemical attraction for one another, which
causes them to combine so violently that they produce
only the shorter vibrations of light towards the blue end
316 ANIMAL ELECTRICITY
of the spectrum, and among them are none of the long
vibrations of heat.
Animal electricity has been credited with a power that
controls the spirits of the dead, and induces them to rap
out answers to credulous questioners: and also with power
to give movement to inanimate objects, causing tables to
gyrate and tambourines to fly and play on themselves:
but these manifestations and the interpretation of them
we will leave to their believers. After all they are no
more incredible than electrons and carbonaceous emissions
from the sun.
COMETS' TAILS
CHAPTER XLI
COMETS.
THERE is one set of rays that have lately been ascribed to
electricity and which we are therefore justified in examining,
and these are comets' tails, but before we tackle them it
will be as well to see what we know about comets as a whole
and to form some clear conception concerning them.
It is certain that a comet is a cluster of stones surrounded
by what appears to be an atmosphere.
Comets vary in size, but in a good specimen the cluster,
which is called the nucleus, is probably larger than most
of the minor planets, and the atmosphere, which is called
the head, extends to an enormous distance round it. The
cluster may have a sectional area equal say to something
between Russia and Wales, and its globe of atmosphere
may be five times the diameter of the earth, and though
the dimensions of the head and its nucleus change, getting
larger, as they enter within our orbit, their relative
dimensions do not differ much, and, so long as the comet
is visible, it is plain that its atmosphere does not approach
to the form of a mere skin such as our atmosphere of a
hundred and twenty miles does to our earth, but that it
is always many times the diameter of the nucleus. The
measurement of the head of the comet is of course easily
made, but that of the nucleus appears to be more difficult
and astronomers seem to be shy of committing to paper
their ideas on the subject. Halley's comet, which has
lately come and gone, has, through careful watching,
added a good deal to our knowledge, and some of the
317
318 COMETS' TAILS
points discovered we will particularly discuss, but all the
information regarding it that has been given to the public
seems to have come from outsiders and not from
astronomers.
We do not yet know all that is to be known about
comets, therefore if we try to fill in the gaps it must be
with ideas, and the more commonsense the ideas are,
the more likely they are to be found to be facts hereafter.
In the description that follows facts are supplemented
with ideas.
The nucleus of the comet is a cluster of loose stones
held together by mutual attraction of cohesion, and the
light they show when distant from the sun is reflected
sunlight only. Whatever may have caused them to come
together, they were cold before they did so, and though
they may now grind together they certainly do not do so
with sufficient effect to produce any light or even any
material amount of heat, and they are still practically of
the same temperature as space. As a body the nucleus
is of much too small a bulk to retain heat and there is no
conceivable force to produce heat in it while it is far from
the sun.
Photographs of Halley's comet taken before it reached
the confines of the earth's circuit show that the atmosphere
was illuminated as well as the nucleus and therefore that
it cannot consist of a mere mixture of gases such as is
our atmosphere, for pure, dry air does not reflect light
the aether light vibrations pass through it and there is
no return although there is some slight refraction, so we
may be certain that the material that forms the head is
not gas so long as the comet is beyond our orbit. It is
a mixture of substances in the form of dust which is kept
in place by gravitation towards the nucleus, and which,
being dust of solid material, can reflect sunlight though
not so strongly as the more solid nucleus.
COMETS' TAILS 31
No part of the comet when away from the proximity
of the sun is self-luminous: there is nothing to make it so,
and everything to prevent its being so: but it is different
when the comet is within our orbit, for then the nucleus
gives out self -produced light, and the atmosphere a mixture
of that and of reflected light. This fact of the luminosity
of the nucleus enables the spectroscope to show that
there are several substances now present in the gaseous
form in the atmosphere, and this change, there is no doubt,
has been brought about by the same agency that has
inflamed the nucleus.
It was discovered while Halley's comet was lately within
our limit, and no doubt will be found to be a condition
of every comet when near the sun, that there was a great
eruptive discharge of material from the nucleus in the
direction in which the comet was moving: not, you must
clearly understand, in the direction of. the tail which is
in a line away from the sun, but at right angles to that line
and flying out before the nucleus: some of the projected
material being shot straight forward, and other parts
obliquely and to the sides. All this effect is produced by the
impact of the comet with the stones of our zodiacal nebula.
It will not be necessary for us to study deeply the subject
of our solar nebula, called the zodiacal light, which extends
in the plane of the sun's equator to within about two
million miles of us, and has a depth at the sun's poles
of about eleven million miles. It is a great cloud of
stones of various sizes, some perhaps the size of a house,
but none large enough to show by reflected sunlight as
a separate body. It is circulating round the sun probably
faster than the earth and at that part which is nearest to
us has a velocity of more than fifteen miles in a second
contra clockwise in the same direction as ourselves: and
a comet when it comes among these stones is as often as
not moving in the contrary direction at about forty-five
320 COMETS' TAILS
miles in a second : so the stones may crash into the nucleus
with a rate of about sixty miles a second.
It happened a short time ago that a very splendid
meteor was observed with great accuracy from two places
and was found to be flying through the air at a height of
forty-seven miles, and with a velocity of twelve miles in
a second: and it was changed by the encounter with the
thin air at that height, though going at that comparatively
slow rate, to an incandescent mass that was consumed in
a few moments: how enormously greater must be the
intensity of the conflagration when solid meets solid with
five times the velocity. On one occasion a comet was
observed to be broken in two by this bombardment of
the zodiacal pellets, and Halley's comet has suffered
so badly that it will probably not be able to endure more
than a few more encounters.
The material of the comet's atmosphere when near the
sun is the result of this action and is a mixture of dust and
gases while it goes on, but when far from the sun the gases
would freeze and remain mixed with the solid dust, and,
owing to the small size of the nucleus, there would be little
diminution of the atmosphere by any sort of sedimentation
of the dust even in a century.
During the bombardment the nucleus has a bright spot
which is not central because the explosions on its advanced
side cause that side to expand and the head also is bulged
by them in that direction, but it was observed that none
of the streaks of light caused by the rebounding meteors
passed beyond the limits of the comet's atmosphere.
The material no doubt went further but, at the moment
that it left the atmosphere and its gases, it lost gaseous
material with which to combine and its combustion was
stopped.
On previous occasions when other comets have passed
in the space between our orbit and the sun, temporary
COMETS' TAILS 321
protrusions have been noticed pointing towards the sun,
or sideways, and they have been called advanced tails >
but they were no doubt caused by more stupendous
explosions than usual following . the encounter with some
of the larger pellets of the nebula and carrying the atmo-
sphere outwards with them.
The head of the comet has always been observed to
increase in size and the nucleus to become brighter as it
approaches the sun, and this used to be put down to the
fervent action of the sun's rays, which is an idea that has
very little foundation of likelihood. Halley's comet
showed both these actions though it was but little nearer
the sun at any time than Venus, and Venus has always
been supposed to enjoy much the same conditions of
temperature as ourselves, and certainly shows no signs
of combustion: and besides, with such an enormous depth
of cometary atmosphere to work on, those of the solar
vibrations that were reduced to heat rays would be entirely
exhausted before they reached the nucleus: so we may
with all confidence attribute the expansion and the in-
creased brightness of the comet to its encounters with
the stones of the zodiacal nebula, and to the actual con-
flagration in the comet caused by them.
There is only one more point to be noticed regarding
the head of the comet, and that is that its dusty atmosphere
must not be considered as dense as a London fog. The
dust is probably composed of pieces of all sizes up to
moderately-sized pebbles, and they need not be very
thinly scattered, for although the stars are seen through
the whole depth of the head, diffraction helps to allow
this, and the individual particles slip so quickly past that
no interruption of the stars' rays is appreciable. We
know that there is an immensely greater thickness of dust-
laden space surrounding the sun, and that it passes between
us and many of the stars, and yet no trace of diminished
322 COMETS' TAILS
light has been observed in them on that account. The
only reason for supposing that the dust of the comets'
atmosphere is thinly scattered is, that if the whole of the
nucleus were broken up and dispersed it could not give
more than a thin powdering : for if the globe of atmosphere
is fifty times the diameter of the nucleus, which appears
to be about the case, then the head has just a quarter of
a million times the cubic capacity of the nucleus, and each
piece of the broken-up nucleus whatever its size would be
surrounded by an empty space two hundred and forty-
nine thousand nine hundred and ninety-nine times as big
as itself. But the comets' atmosphere, judging from
its power of reflection, is certainly more crowded than this,
and we may reasonably suppose that when the comet
was made it was a collection of material of all sizes, and
that the bigger pieces collected together to form the
nucleus while the smaller remained scattered in the
atmosphere.
The nucleus of a comet if it is big enough will at all times
occlude a star, but it is only when the comet is within our
orbit and has gases in its atmosphere, due to the violent
combustion of the zodiacal stones, that there can be any
change in the aspect of a star owing to the interposition
of the comet's head: then the light of the star would be
diminished and its position would appear altered by
refraction through the gases of the head.
The path of a comet is a parabola for those that come
once and never return and an ellipse for those that are
periodic, but in no case does the path of the comet fall in
the plane of the ecliptic. If you will imagine our orbit
as a solid ring with a sheet of thin material stretched on
it like the parchment of a tambourine, then you have an illus-
tration of the plane of the ecliptic, and the sun is stuck near
the middle of it with half its body protruding from either
surface. Now the path that a comet would take to pass
COMETS' TAILS 323
round the sun would approach this plane at some angle
and would pass through dipping below the other surface
and rising again towards it and passing up through the
plane again at a point on the opposite side of the sun.
It is therefore only at those two points where the comet
passes through the plane that a comet can come in line
between the earth and the sun, and it is believed that
Halley's comet did this at its last visit, and that then the
sun's light came to us through the comet.
The ecliptics of all the planets coincide more or less
closely to the extension of the plane of our ecliptic, and
the divergence of the comets' paths from this plane very
much lessens the small chance of collision between a
comet and a planet, but such a collision would not only be
disastrous to the planet struck, but would upset the
working of the whole of the solar system, and as all the
planets, by their attraction, disturb the courses of comets
and make them irregular, it is not impossible that this
action of the planets may bring about their own destruction.
However we appear to have evaded this possibility for
a few million years at the least.
There is (besides this attraction) a disturbing element in
the courses of comets as has been proved by a long series
of observations of Encke's comet. This comet has a
period of about 1,210 days, and every return of it is two
and a half hours shorter than the previous one. This,
as we can easily understand from what we have already
learnt, is accounted for by the battering of the stones
of the zodiacal nebula, which would in time reduce the
comet's ellipse to a circle. Encke's comet is a very small
one and only to be seen through a powerful telescope,
and, on account of its small size, and its circling with
the stones of the nebula, gets little bombardment, but it
may come to sudden destruction by meeting a monster
pellet, and probably all periodic comets are at last
324 COMETS' TAILS
destroyed by, and their material scattered among, the
stones of the nebula.
Iron, carbon, and some other substances, have been
discovered by the spectroscope as being part of the material
of the comet, and the composition of its solids is probably
in no way different from that of the meteorites that fall
through our air.
COMETS' TAILS
CHAPTER XLII
COMETS' TAILS
WHEN a comet first comes into sight as it journeys towards
the sun, it is seen to be like a small disc, palely lighted,
with a brighter spot at its centre, and with no sign of a
tail: the tail only begins to appear when the comet has
come within ninety million miles of the sun, that is to say
when it has entered among the stones of the zodiacal
nebula : and it disappears again when it leaves the nebula.
The tails of comets vary, but in what may be called a
typical comet, the tail is a continuation of the head,
passing back smoothly without any contraction in the
way of a neck, and gradually widening out till it terminates
either square-cut, or tapered like the end of a dry water-
colour brush. The tail is less bright than the head, and
what appears to be the shadow of the nucleus divides it
into two great rays and this separation is especially marked
just behind the head.
The length of the tail mainly depends on the position
of the comet in the nebula: those that pass close to the
sun's equator have long tails approximating to the ninety
million miles' depth of the nebula in the sun's equatorial
plane: and those that pass otherwhere or further from
the sun have shorter tails. Also some small comets,
though well situated as regards the nebula, have small
tails because there is little light passing out of them from
the sun, but the photographic plate can trace the reflection
of the continuation of the actinic aether vibrations much
beyond the end of the visible tail and until they reach
325
326 COMETS' TAILS
the verge of the nebula. This is a point that we must
particularly remember that the tail does not extend
beyond the nebula.
Occasionally we see photographs of comets' tails show-
ing a wavy appearance of alternate light and dull patches.
This, if true to nature, is not due to any material shot out
of the comet possessing the property of blazing up at one
part of its course, then losing energy, and then blazing
up again further on : but is due to the irregular distribution
of the stones of the nebula which are no doubt more
densely aggregated in some parts than in others; a condi-
tion that is known to be common to other nebulae. How-
ever, a good deal of the abnormal variation shown in
photographs is plainly due to touching up.
Short temporary tails have been occasionally seen as
was the case with this Halley's comet weeks before the
comet came within the zone of the nebula, and this is
because our nebula, like other nebulae, probably has spiral
trails projecting beyond its general outline and supplying
us with our shooting stars, and one of these trails showed
the passage of the comet through it by reflecting the light
flowing from the comet. For light is always flowing from
the comet although we can see none of it until it falls on
something to reflect it: just as when the sunshine coming
through a window marks its course in the air of a dusty
room, but has no visible track if the air is pure and free
from dust to reflect its light.
" The light from the comet's tail is reflected light."
The comet's tail is the reflection from the stones of the
zodiacal nebula of the sun's rays that have passed through
the head of the comet and that have been changed by that
atmosphere to light rays. Before they entered the comet
they were actinic rays incapable of giving light, after they
had passed through most of them were changed to light-
giving rays. Philosophers are agreed that the rays emitted
COMETS' TAILS 327
by the sun have neither heat nor light until they encounter
our atmosphere, and of course they include, in this property
of producing vibration change, the atmospheres of the
other planets and also the atmospheres of comets which
are immensely more extended than ours.
The sun is in far too excited a condition to produce any
vibrations but those of the ultra-violet, which have no
light-producing power until they have been reduced to
the longer and slower vibrations that cause light. Before
they are thus reduced by the atmospheres, any of them
falling on the stones of the nebula would be reflected
unchanged, and a part of those reflected to us would be
reduced by our atmosphere to heat and light rays, and we
should see a faint zodiacal light. But those that have
passed through the great depth of the comet's atmosphere
are no longer actinic but have become light -producing,
and they illumine the stones, and that luminosity is re-
flected to us as actual light the comet's tail.
The form that the tail shows us depends on its position
and on perspective. All comets' tails are wider than the
comets they come from: a tail forty-five million miles
long would be actually twice as broad at its end as the
head it started from, because it would be twice as far
away from the sun: but if it was projected towards us, it
would appear many times broader at this end, and the
outlines of its sides instead of being straight lines, as they
really are, would appear curved : while if the tail happened
to point away from us, it would seem to be narrowed to
nearly a point at the end. In most positions the tail
seems to sweep in a great curve, and this is due to celestial
perspective which causes all lines, except those that
point to the zenith, to appear curved. Therefore if the
comet happens to be on any part of the circle that passes
through the sun and the zenith its tail will be seen as
straight, and if away from that line it will appear to be
328 COMETS' TAILS
curved. Halley's comet at its late visit showed these
diversities of appearance: its tail was curved till it came
near the direction of the sun and earth and then became
straight. This appearance of curvature is a deception
as comets' tails are straight.
Comets have occasionally been reported as having minor
divergent tails like separate threads of light, and it is not
impossible that rays may be reflected from some part of
the nucleus by which these lines of light could be produced,
but the illustration of these lines as straight beside a curved
tail is wrong: and either the lines are drawn badly, or
they are the result of reflection in the telescope lenses or
in the spectacles of the observer. Also comets have been
seen with nearly as many tails as the ship's cat, and this
also is possible if we can suppose that some grand ex-
plosion has temporarily broken up the nucleus and that
each part casts its shadow.
These, and the irregular and ragged appearances that
are sometimes presented owing to the irregular distribution
of the stones of the nebula, are all the chief variations to
be seen in comets' tails and they can all be explained by
familiar causes and require no call for faith in vague and
far-fetched fancies, but there are popular representations
of comets which have been published lately that none but
a metaphysician could account for.
Descriptions and pictures (even photographs) all agree
in exaggerating the luminosity and the size of comets
and some of both these sorts of productions have been
published which it is impossible to make any sense of
because they are inaccurate through invention, exaggera-
tion, want of perception, and want of artistic ability.
Those who missed seeing comet 1910a and have seen these
fancy flights of pen and pencil must have felt that they
had lost an amazing great sight, for a meteor such as was
represented would have greatly rivalled the sun in
COMETS' TAILS 329
splendour, whereas in truth the nucleus appeared of the
size of a small star both pale and hazy, and neither the
head nor tail was visible at all if there was even a slight
mist in the air. Also in these drawings this comet was
placed at every angle to the horizon but the right one
which was perpendicular nearly, and many uncouth and
fantastic illustrations have been given of the heads and
tails of this, and of Halley's comet. In fact hand drawings
of comets are often atrociously bad and grossly exaggerate
every peculiarity. Photographs greatly exaggerate the
light but the other details are given for the most part
correctly.
A short time ago the most commonly received idea as
to the production of the comet's tail was, that it is the
material of the comet shot out of it either by the comet's
own force or by the driving power of the sun's rays. You
will agree that it is hardly necessary to take the trouble
to explain that if the comet had any driving power of its
own it could not use it in one direction only, but must
employ it in a general all-round explosive form, so that
the driving power, if there is any, must reside in the sun's
rays, which taken in conjunction with solid material or
even with gases is an idea that seems rather incredible.
We feel none of it here at any rate; we see none of our
atmosphere streaming away to space; and neither Venus
nor Mercury show any signs of tails.
In fact the material theory of comets' tails does not
appear a plausible one; still we are bound to examine all
theories ; but before doing so there is a point that we must
notice. The tail of the comet is pointed nearly directly
away from the sun, and in order to keep that direction
it must be projected with a rapidity equal to that of
light. For instance, if a comet at forty-five million miles
from the sun is moving in its course at forty-five miles
in a second, and its tail is forty-five million miles long and
330 COMETS' TAILS
is projected at the rate of light, then the end of the tail
of that comet will be just a little more than twenty-one
thousand miles behind the straight line from the sun
passing through the comet: and this discrepancy is always
seen and increases the faster the comet travels and the
nearer it passes to the sun: but it amounts to no more
than the loss that is due to the tail being projected with
the speed of light, and therefore, if it is material, whatever
the material of the tail may be, it must travel at that rate,
as any slower rate of projection would leave the end too
far behind. Any idea therefore that depends on the
projection of material from the comet must account for
the material having this projectile velocity of 186,000
miles in a second.
A comet moves fast but it would have taken Halley's
comet about a month to have come the distance that the
sun's light passes over in eight minutes. The sun is
exceedingly powerful and can drive clouds of luminous
material from its surface with the amazing velocity of
one hundred and twenty miles in a second and there is
no faster movement of material known, and yet with all
its power it cannot project them into space. Halley's
comet passed no nearer to the sun than sixty million
miles and to project its material into space the sun must
at that great distance have exerted a force six hundred
times as great as that which it has at its own surface.
It is of no use arguing against this that the restraining
force of gravitation is greater at the sun's surface than at
the distance of the comet, because the sun's force of projec-
tion, if any of it passes into space, must lose energy with
distance in exactly the same ratio as its gravitation loses
it. And besides, on the sun's surface, it is nowhere
apparent that the sun's rays have any projecting force
at all, for the solar prominences are due to purely local
eruptive action of the sun's material: so that as regards
COMETS' TAILS 331
the dispersive action of the sun's rays we have no proof
either on the sun or here, and the idea seems to be a meta-
physical conception with no basis of fact and invented for
the occasion.
Halley's comet took nearly two months and a half to
cross from the other border of the ecliptic, and during
that time had a tail that averaged say twenty million
miles in length: and it was about half as luminous as the
head that is, if it was material, it had about half as much
material in a cubic mile of it as the head had: so that the
tail must have contained in it, at the very least, two hundred
and fifty times as much luminous material as the head of
the comet omitting the nucleus : and this amount of material
must have been renewed every two minutes throughout
these two and a half months and must have measured
altogether, thirteen million times the bulk of the head !
A comet does not exhibit a tail till it is within ninety
million miles of the sun. Are we to suppose that beyond
this exact distance the sun's rays lose their power to drive
the material of the comet ?
The outer layer of the sun's atmosphere is hydrogen
which is the lightest substance known, and yet the sun's
rays cannot drive it away. Why should the rays act so
much more violently on the comet's more distant and
heavier atmosphere ?
Why should the material of a comet's tail at one time
retain its luminosity over a distance of ninety million miles
and at another time not over one million ?
The earth was enveloped in the tail of the comet of 1861.
There was an " auroral glare " which is what one would
expect, but there was not the least trace of any material
added to our atmosphere. How was it that we were
enveloped in the light but not in the substance ?
In every part of its course the material comes with the
speed of light, so even if it has lost its luminescence at
332 COMETS' TAILS
the limiting distance, it cannot have lost its speed. Sir
Oliver Lodge says that " the energy of one milligramme
rushing along with the speed of light is not less than
fifteen million foot tons." The comet's material entering
our atmosphere with that speed and energy would certainly
destroy us.
And besides all this the light from the comet's tail is
reflected light and not the light of luminous material.
Is it necessary to pile up further objections to the
emission theory ? The folly of it has become so apparent
that it has now been ostensibly abandoned and electricity
has been substituted.
But electricity has no light of its own, and this every
scientist knows although they so constantly talk of the
heat and light of the " electric fluid." The light produced
by electricity, whether it is that of the lightning flash or
the glow from a tube in the laboratory, is the light from
contracting material: and any vibrations that the action
of electricity may give to the aether are not vibrations of
light, but are very much longer and more slowly recurring
and incapable of producing light.
And there is no electricity in the sun to send to the
comet. Electricity requires chemical combination to
produce it and to conduct it, and the sun is composed of
gaseous uncombined elements, and therefore neither has
nor can produce electricity.
To say that comets' tails are not produced by luminous
material driven from the comet by the sun's rays but of
material made luminous by electricity is the substitution
of obscurum per obscurius. There can be no material
from the comet to supply the tail whether luminous or not
and there is no electricity to act upon it: and the light
from the tail is reflected light and not radiation from
luminous material.
There seems to be a good deal of misconception as to
COMETS' TAILS 333
what is meant by self-luminous material. The general
idea appears to be that it is a material that produces
light without any action on the atoms of the material
there is no such material. To produce any effect there
must always be a producing action. The luminosity of
luminous paint or of the diamond is not simply the pouring
out of light that has been poured into them, but is due to
the recovery from some crystalline change that was pro-
duced by received light, and the luminosity is consequently
lost by use. The luminosity of phosphorescence and of
combustion is due to the combination of the materials
with oxygen, and lasts only while the combination is
going on, and the materials once combined are useless
for the purpose again.
The '' electric fluid " has 110 light. The examination
of the electric flash shows that it consists of millions of
tiny sparks, which show the combination, or as it is com-
monly called, the burning together of the molecules of
air: and their light in the whole of a lightning flash lasts
for perhaps the twenty thousandth part of a second.
There is no electricity without combination which is
sometimes violent combination giving light, and some-
times easy combination giving none: the current that
produces light in the violently combining air could pass
down a lightning conductor without showing a trace of
light, because of the easier conduction: but in no case
is there any light from the electricity.
To send out a comet's tail worked by electricity, there
would be required a constant emission of material from
the comet to supply the substances for combination,
and a constant emission of electricity from the sun to
work upon the substances, both of which are impossible:
and as there is no material in the space between us and the
sun except the stones of the nebula, there can be no
possible supply of materials for combination in that
334 COMETS' TAILS
region, and there can be no light but what the stones
reflect to us.
Much has been written about electricity in the sun and
all of it based on a supposed connection between sun-spots
and the meteorology of the earth and especially with regard
to the aurora. Coincidence is the most that can be claimed,
for many sun-spots are formed without any sign of meteoro-
logical change here, and meteorological changes here occur
during periods one of which lasted for sixty years
when there were never two sets of spots on the sun and
what there were were very small. Repeated attempts
have been made to find electricity in the sun and a short
time ago the cohere, which is a very sensitive detector of
electric vibrations, was used to discover whether such
vibrations are emitted by the sun, but entirely without
result. There is absolutely no proof of electricity in the
sun and every attempt to find any has failed. Any theory
that includes electric solar emission is therefore baseless.
Ideas that are wonderful and incomprehensible, although
impossible and useless, are more attractive to, and more
believed in by the general mind than simple statements
based on facts: witness table-turning; the gyration of
solid magnetic molecules ; the powers of radium. And in
many cases these wonderful ideas are difficult to disprove.
You dream that you have fallen through infinite space.
A theosophical friend tells you that your astral body,
while separated in sleep from your material body, did
actually fall through space. What can you say ? His
affirmation is as good as your negation. Your doctor
tells you that you are anaemic and that your dreadful
dream was due to inferiority of arterial supply to the brain.
You prefer the theosophist's fancy to the doctor's more
probable fact, because the first gives you a wonderful
and incomprehensible and glorious (and utterly useless)
extension of your being.
COMETS' TAILS 335
" As a rule men freely believe what they wish," and now,
after our study of the subject, you have your choice of
believing in one or another of the prevailing theories, or of
concluding that the comet's tail is a true ray a ray of
reflected sunlight and that it has nothing to do with
electricity.
APPENDIX
CHAPTER XLIII
APPENDIX
'* HAVE you ever thought it worth while," said Socrates to
Alcibiades, " to try to find out, or learn, what you believe
you already understand ?" And the answer was, " No
certainly."
Said Socrates to Theages: " If you wish to become an
expert in a science, do you not address yourself to those
who profess to teach it ?"
This book was undertaken as an endeavour to find out
whether what we understood that we had learned about
electricity is true : and the result like the end of the marriage
service, has been amazement.
Before this book was thought of, the writer was engaged
in the search for the cause of gravitation,* and as some
scientists said that it was due to electricity he turned to
examine the idea, and, although he had been taught
electricity, and had attended lectures, and had seen and
done many experiments, he found, much to his astonish-
ment, that he did not know what electricity is so he
bought books on the subject nearly all of them started
with the experiment, familiar to our childhood, of rubbing
a stick of sealing-wax on our coat- sleeve and attracting
bits of paper with it, and this was supposed to explain
what electricity is, and to the writer's still greater
astonishment no scientist had got any sensible idea beyond
this: they knew what electricity could do, but not what it
* The cause of gravitation has since been discovered by the writer,
and electricity though it is due to gravitation has nothing to do with
its production.
336
APPENDIX 337
is, and in explaining its effects they did not agree and
apparently it was a case of every man his own electricity,
so the search for clear and indisputable teaching was
disappointing, and the want of agreement of opinions made
one inclined to think that another extract from Plato was
applicable. k " For one certain sign that they do not know
it, and that they do not know how to teach it, is^ that they
cannot agree about it among themselves." The con-
firmatory extracts that have been used in this book are
therefore restricted for the most part to those about which
there is a general agreement, or that describe some fact,
and may be relied on, while other extracts which have been
given as showing diverse views, must be taken as the
reader chooses.
There is one cardinal point on which all the latest
writers on electricity seem agreed, and that is the emission
theory, and the author of the " New Physics and Whispers
from an Old Pine," who says that sound is material,
consequent^ claims them as cobelievers. When we were
young we were told that emission was knocked on the
head because it could not explain the polarization of light :
how then does it explain the polarization of what are called
electric waves ?
In planning the arrangement of this book, the sealing-
wax and paper business seemed so utterly void of anything
from which a plain deduction could be made, that it was
rejected as a starting-point and the voltaic experiment
examined, and in this the chemical action in the cell gave
so good a promise of relative meaning and need for explana-
tion, that it was chosen as the subject for the first article
of the book, and most happily, for without the lessons
learned from the cell it is unlikely that any sensible
conclusion could have been arrived at.
The study of this book has no doubt led its readers to
conclude that electricity is a vibration of the aether associated
338 APPENDIX
with the outside of the molecules of compound fluids,
but the inconsistent opinions of the scientists of to-day
as regards vibrations leave one somewhat dubious as to
what vibrations really are and is one of the most puzzling
things in scientific teaching. A sound from somewhere
sets the air in motion and one of your lamp-shades rings
a responsive note. An obliging scientist tells you that
the air enclosed by the glass is of exactly that depth that
is a measure or multiple of the wave-lengths of air that have
come from the distant vibrating object, and that the glass
responds in consequence: that the glass itself could of
course produce no sound unless some force 'were spent upon
it. And, he continues, this lovely December rose of yours
is in the same way dependent for its colour on extraneous
force: its molecules react with the light falling on it, some
of it is absorbed by them and some of it is rejected, and the
rosy hue you see is the rejected light mixed with light
reflected from the surface. Then the flower does not
produce its own colour ? you ask. He looks at you with
pitying superiority and says, It must receive light
vibrations or remain unseen in form or colour. "There
is no colour generated by any natural body whatever."
And yet he will tell you that these bodies produce
vibrations of heat and electricity. That instead of being
the inert things that their want of initiative as regards
sound and light would lead you to suppose, that the
molecules are all brimming over with self -created force,
and that " a single pennyweight of hydrogen has in itself
more energy than could be produced by burning fourteen
chaldren of Wallsend cobbles": and that every molecule
of every substance is composed of two equal antagonistic
electricities which would immediately cancel each other
anywhere else, but here are harmoniously blended till
excited to emission in some way, and that the rest of the
molecule is heat: and that this astonishing solid made of
APPENDIX 339
motion, that cannot produce a single vibration of light,
can for a thousand years produce vibrations of heat and
electricity.
You murmur something not for publication, and wonder
why that flower that is half hydrogen should smell so
sweetly cool: and why, when we have been flooded with
hydrogen in the form of rain, we should have had so
abominably cold a summer: and why this particular
scientist, a third of whose portly person must be hydrogen,
should, when occupying the hearthrug, absorb heat instead
of radiating it as scientific theory would lead one to suppose
he ought to do.
Modern scientists do not seem to have gone in for the
analysis of the elementary forces, and it is difficult to get
any ideas for the purpose from modern scientific works.
They are so much taken up with explaining complicated
experiments to suit some dubious theory, and the experi-
ments are done with such complicated contrivances in
which mixed gases are worked on by refraction, reflection,
rarefaction, electricity, magnetism, rays, radium, corpus-
cles, electrons, and nuclei, all mixed together and measured
with artificial constants, that to ordinary intellects the
result arrived at is about as convincing as the patter of
a conjuror who smashes up a watch, puts it into a hat,
and pulls out a white rabbit.
It is by the study of simple experiments that we can best
hope to learn the origin of nature's forces: experiments
in which that force alone is engaged which we want to
study: and the author has tried to do this in this work,
and the conclusion that the evidence has forced upon him
has banished emission, and the immaterial electron, and
the effusive corpuscle, to their sure natural abiding-place
in the " equinoctial of Quebus, 91 from the poles." But
he neither expects to make converts or friends by this,
nor yet to stop the belief of others in mystical impossibilities.
340 APPENDIX
Why should his disbelief in emission avail while it is still
advocated by well-known authorities although the absurd-
ity of it was clearly shown by Lord Kelvin.
There is a story told of Alexander the Great. He was
encamped on the edge of a desert, and wishing to think
alone, he wandered far into it : he came upon a skull which
seemed to him such a remarkable skull that, taking it up
and intending to show it to a philosopher who was in
camp with him, he turned and went back. And as he
went the skull became heavier and heavier till he could
carry it no longer: so going to the camp he brought out
the philosopher to see the skull, and pointed out to him
how wonderful it was, and told him how astonishingly
heavy it had become. "It is astonishing," said the philo-
sopher, "but if you will put a little earth on the skull, it
will become as an ordinary skull."
" Man goeth down to the pit and all his thoughts
perish,"
No thoughtful man, scientist or other, wishes to think,
that when earth to earth is dropped over his skull and it
remains to become " no more than foul mould," that all
the splendid thoughts that once filled it are not even
dissipated in space but are nowhere: so to preserve the
thoughts collected in this work and to give them a chance
of continuance, the author has decided on printing a
hundred copies which he will give to those scientists whom
he hopes may take an interest in his deductions: and if
they would in kindness point out any clear experimental
proof that disproves his deductions, he will be thankful,
and if they will send him a word of encouragement he
will be eternally grateful.
His principal reason for so restricting the publication
is reviewers. No book, except the indecent novel, sells
APPENDIX 341
if the reviewers do not praise it, and they praise nothing
that is new unless it is by some one notorious. Reviewers
have always been the bane of independent thought. If
there had been reviewers in Adam's time we might have
been going about in his fig leaves now. " A reviewer kept
back the advancement of science, as advocated by Young,
for half a century or more." What ! says the reader, is
he comparing himself to Young ? Not a bit, neither is
he comparing the modern reviewer with Brougham. He
was an exceedingly clever lawyer, quick to see a weak
point and to make full use of it, bitterly sarcastic and over
bearing, and a clever writer, but, although he was a
President of the Royal Society, he knew nothing in science
except what was told him, and could not see into that
beyond the end of his peculiarly flexible nose. In science
he was an exemplification of echo vox et prceteria nihil
and modern reviewers are exact copies of him in that
respect: they are superficial copyists who only echo the
last most startling cry, and the amount of original know
ledge that they possess is like King Shrovetide's robes
" nothing before and nothing behind with sleeves of the
same."
The writer has guarded his statements in most cases
by opinions of famous scientists, and these would be as
stumbling-blocks to the reviewers in any attempt at par-
ticular criticism, so they would fall back upon unguarded
expressions, or misspelled words, or ill-arranged sentences,
and would condemn on generalities, for " on any argument
they can many times by a slight, laugh over what they
could never seriously confute." But the author wants
none of such criticism and would say, " But if by error
led astray, I chance to wander from the way, let no blind
guide observe in spite I m wrong who cannot set me right."
Investigation went pari passu, when necessary and
possible, with the writing of this book, and the writer
342 APPENDIX
tried to present his mind as a tabula rasa for the collection
of facts, and each chapter was completed separately and
without thought of what was to follow : but it is difficult
to obliterate first impressions, and few people have an
individual basis of knowledge ; most learn by rote and few
by reason : they were taught, and accepted what they were
taught, and never try to verify their teaching: they follow
the flock with a blind belief in authorities. Imagine an
Irishman, brought up to believe that green is the purest
of pigments, being told that it is a mixture of orange and
blue : it will require much proof to convince him, and then
compelled against his will, he will be of the same opinion
still. Early teaching tinges our ideas, and in several
places in this book has led the writer to the expression of
premature conclusions: they have been allowed to remain
and no change has been made in the original manuscript
except the smoothing of a rough phrase, or the better word-
ing of a paragraph to make explanation clearer, therefore
these expressions (which the student should obliterate)
are to be taken in the same way as the opinions of a
witness, which the judge tells the jury, are not evidence:
they are left as showing the tend and change of thought,
and must not be quoted as being the present opinion of
the writer, or in any way as confuting the final deductions.
The bias that the early teaching of disputatious subjects
must produce, should make teachers very careful in their
choice of subjects with which to store young minds.
Childhood is very receptive and very retentive of ideas,
and has little reasoning faculty: and there is perhaps
nothing which helps more to success in life than a good
memory which is never so well acquired as in childhood.
The aim of education therefore should be to teach a child
morality, and such subjects as require memory history,
geography, grammar, Latin, and foreign languages: and
subjects that in addition to memory teach consequent
APPENDIX 343
reason and facts about which there is no possibility of
error arithmetic, geometry, and music: while law,
medicine, chemistry, engineering, and physics, should not
be approached till youth has put off childish credulity
and can consider with a discriminating mind what is told
him. This is especially needful as to physics, for what
chance would a youth have of sanity if he took as gospel
in childhood many of those ideas which are now advanced
by scientists and which must indubitably perish: such as,
that because two bodies cannot occupy the same place,
they must therefore repel each other when close together:
that the aether is cogwheeled or vorticate: that atoms
possess perpetual motion: or the planetary system of
atoms: or the bombardment of gases: and many other
vain fancies that it would be tedious to mention?
" When people are content to remain mere echoes of
other men's opinions, or purveyors of ready-made politics
or philosophy why, they are afraid to think and inquire
lest they should find truth unsettling."
This book took two years to write, and the printing
of it has been further delayed by Albertus Magnus' worst
demon, therefore any topical references must be under-
stood as referring to the years 1908-10, in which years
it was written.
INDEX
ACCUMULATOK, 179
Adams 75
J&ther, 224, 227, 233, 246
Air, conduction by, 135, 209
constitution of, 55, 210
Alloys, 90, 95, 114
Alternating currents, 199, 203
Amalgamation, 4
Angot, 267
Animal electricity, xl
Anions, 22
Anode, 6, 20, 27
Appendix, xliii
Arc light, 67, 114, 198, 230
Armstrong, 57, 85, 202
Arrhenius, 265
Atmospheric electricity, 183, xxxiii
Atomic weights, 90, 106
Attraction and repulsion, 148, 167,
169, 177, 190, 212
Aurora, xxxiv, xxxv
connection with electricity and
magnetism, 264, 273,
276, 277
with water vapour, 269, 276
- height of, 268, 271
light, colour, and spectrum of,
267, 270, 272, 275, 278
locality of, 269
movement of, 270
shape of, 268
sound of, 267
- the gulf, 268
- theories regarding, 264, 273, 277
time of, 270, 276
B
Benham, 258
Berzelius, 34
Bjerkness, 93
Bolometer, 113
Bone and Wheeler, 71, 98, 103
Brush discharges, xvii
Carbon, 114
Catalysis, 9
Cavendish, 314
Chemical change in conduction, 77,
84, 93, 100, 134
combination, 8, 13, 19, 82, 211,
223
Clausins, 21
Clouds, 296, 300, 305
Coherer, 106, 235
Cohesion, 103, 122
Comets' tails, xli, xlii
Condensation, 260
Condensed air, 40, 97, 106, 111,
112, 161, 190, 192, 194, 201, 206,
210, 220, 235, 241, 244, 310
Condenser, 253, 180, 182, 216
Conduction, xi, xii, xiii, xiv, 157,
184, 192, 200, 204
by air, vapour and gas, 77, 79,
117, 120, 131, 135, 192
by condensed air, 98, 106, 112.
191
by flames and .heat, 77, 93, 96,
113, 158
-by fluids, 22, 87, 117
by solids, 90, 111
copper as standard, 92
on surfaces, 91, 94, 103, 105
theories of, 94
Conductors, 92, 111, 128, 300, 302
non-metallic, 93
surfaces of, 90, 96, 98, 104
Conservation of energy, 231
Contraction, 66, 249, 254
Convection, xxv, 78, 119, 122
Crookes, 84, 203, 247, 248, 249
Crosse, 258
Current, 2, 6, 9, 20, 25, 32, 83, 110,
116, 135,209,221,246
action of, 7, 29, 142, 218
on junctions, 64, 69
on wires, 94, 206
344
INDEX
345
Current, alternating, 198, 203
direction of, 6, 140, 163, 168
inertia of, 72, 165, 182
movement by, 193, 195, 198,
217, 223, 234, 247, 253, 305
physical effect of, 34
production of, 5, 10, 76
requires a circuit, 5, 24, 204
- velocity of, 20, 194, 208
Dampier, 282
Daniell's cell, 14, 88, 129
Darwin, 1, 283
Davy, 17, 44
Decomposition of water, 7 -
De la Rue, 129
Dewar and Fleming, 114
Diacathodic rays, 253
Discharge, xvi, xvii, xviii, 234
by flame, 133, 158, 184
by smoke and gases, 132, 301
chemical action in, 129, 131,
133, 235
colour of, 83, 123, 127, 135, 137
from clouds, 299, 301
from points, 120, 126
in vacuum tubes, 82, 137, 246
light of, 123, 128, 141
noise of, 142
positive and negative, 124, 128,
135, 140
track of, 130
Dissociation, 19, 21, 25, 86, 137
Double refraction, 218
Dry Pile, 39
Du Bois-Raymond, 314
Dust, 82, 120, 122, 183, 191, 259,
284, 298, 3pl
E
Earth currents, 170, 183, 261, 273
Effusion, 70, 78, 104, 200
Electric dissociation, 19, 25
mortar, 142
- motion, 23, 31, 137, 246
preference, 15, 17, 87, 222
smell, 135
spark, 129, 135
striae, 138
- whirl, 120, 122
wind, 119-123
Electrical machine, 46, 54, 224
Electricity, xxvi, xxvii, xxviii,xxix
and friction, 46, 50, 58, 81
compared with heat, 119, 223
dissipation of, 119, 208
is motion, 24, 31, 138, 195, 197,
246
positive and negative, 138, 156,
199, 225, 299, 307
production of, 10, 27, 47, 62, 261
requires fluid or vapour for
conduction, 58, 100, 108, 116
residual, 184
single or double, 135, 140, xxix
- speed of, 20, 194, 209
Electrochemical action, 3, 9-17,
24, 53, 61, 72, 82, 123, 129, 132,
134, 179, 195, 198, 204, 207,
235
Electrodeposition, 41
Electrodes, action at, 11, 27, 128,
133, 135, 143
of heat on, 136
- shape of, 128, 133, 139, 247
Electrolysis, 6, 19, 24, 40, 76, 87,
89, 100, 105, 108, 141, 143,
151, 156, 161, 163, 185, 198,
201, 210, 216, 224, 305, 312
and effluves, 69, 78, 104
in air and gases, 77, 117, 135
theories of, 8, 20
Electrometer, 80
Electromotive force, 25, 88, 90, 1 10,
116, 122, 129, 137, 143, 151, 156,
161, 195, 220, 234
Electrons, 200, 208, 212
Electroscope, 77, 147
Elements, 12, 40, 89, 93
Emission, 197
Encke's comet, 323
Energy, 23, 26
Evans, 91
Evaporation, 259, 297
Exhaustion, 250
Expansion by electrolysis, 88, 142,
307, 309
Experiments connected with air
skin, 51, 97, 105, 236
atmospheric electricity, 257
conduction, 84, 91, 96, 258
convection, 187
discharge, 49, 120, 130, 136,
184, 199
346
INDEX
Experiments, electrolysis, 142,
217, 224, 246
electromotive force, 224, 228
- heat, 103, 113, 136
induction, 162
influence, 145, 158, 213, 216,
221, 235, 237
ions, 82
molecules, 56, 70, 95, 104, 249,
252
static electricity, 47, 54
thermoelectricity, 62, 71
ultra-violet light, 200
- vacuum tubes, 137, 172, 253
- voltaic electricity, 3, 18, 34, 76
water skin, 107, 236
Faraday, 20, 58, 104, 125, 197, 212
Fireballs, xxxvii
Fitzroy, 284
Flammarion, 254, 203
Forbin, 281
Force, S>, 65
Franklin, 153, 228, 259
Friction, 46, 50, 58, 61
G
Galena, 64, 76
Galvani, 46
Galvanometer, 63
Gases, electric action in, 78, 100
Geissler's tubes, 137, 172, 277
Globe lightning, 290
Glow discharge, 123
Goldhammer, 251
Goldstein, 254
Gravitation, 26, 29, 279
Grotthuss, 8, 20, 21
Gymnotus, 311
H
Halley, 317, 319, 323, 326, 329, 330
Heat, action on electrodes, 136
and discharge in air, 131, 138
compared with electricity, 144,
223
effect on solids, 95, 98, 185, 207
from current, 34, 206
from resistance, 111, 113
in circuit, 5, 64, 99, 112,206
and conduction, 77, 93
Heat of discharge, 141
of metallic junction, 62, 64, 66,
69
production of, 50, 66, 72
Hertz, 240
Hertzian waves, 150, 239, 243
Hittorf, 84
Hopkinson, 85
Humboldt, 314
Ignis fatuus, 285
Incandescent lamp, 91
Induced currents, 162, 165, 169
Induction, 125, xxii, xxiii
coefficient of, 176
of materials, 174, 176
storage by, 177
- waves, 167, 171, 224, 235, 239
Inertia, 24, 72, 140, 165, 182, 201,
208
Influence, xix, xx, xxi, xxviii
action of, 158, 160, 212, 218,
221, 239
and atmospheric electricity, 263
charge by, 145
compared with heat, 144
conveyed by aether, 148, 157,
235
machine, 148
the same as electromotive force,
161,220
vibrations, 148, 151, 154, 235
Insects, light of, 315
Insulation by gases, 78
Interference waves, 171, 294
Invar, 95
Ions and ionization, 20, 78, 80, 86,
89, 91
J
Jaumann, 251
Junctions, action of current on, 62
K
Kathions, 22
Kathode, 6
stream and rays, 247
Kelvin, 85, 215, 259, 340
Kinetic energy, 166
Kolbe, 226
Krypton, 275
INDEX
347
Langley, 114
Larmor, 239
Lebedeff's wave chart, 246
Le Bon, 70, 154
Lemstroem, 271
Lenard, 247, 249
Leydenjar, 149, 180, 184,199,216
225, 227, 235
Light, 233
effect of, 75
of discharge, 130, 141
in vacuo 138
of incandescent lamp, 114
Lightning, xlviii, xlix, 87
attracted by metal, 303
conductors, 300, 302
depilation by, 308
light of, 300, 309
physiological effect of, 87, 306
protection from, 309
return shock, 307
Lines of force, 173, 212
Liquid air, 54
Lodge, 23, 211
Luminous material, 332
M
Magnesium flame, 158, 200
Malepterurus, 314
Marconi, 242, 243, 244
Maxwell, 168, 184, 243
Medium round conducting wires,
94, 167, 209
Metals, action of heat on, 64
of impurities in, 66
as conductors, 90
Molecular action in discharges
120, 128, 137, 140
Molecules, 8, 14, 55, 107, 157, 185
218, 227, 237, 244, 252, 298,
306
action of current on, 88, 195
218, 227
and heat, 66, 233
effect of exhaustion on, 250
Motion and matter, 197, 222
conduction of, 196
N
Napoleon, one metal cell, 12
Nerve action, 36
Nipher, 199
Nonconductors, xiv
O
Oscillation of spark, 166, 182, 239,
305
Oscillator, 199, 240
Osmosis, 17
Otto von Guerick, 46
Oxyhydrogen flame, 66
Pettier effect, 64
Physiological effect of current, 37
Poggendorf, 32
Polarization, 12
Polarity, 164
Porous partitions, 14, 17
substances and electricity, 56
Potential, 11, 18, 25, 40, 52, 71, 256,
261
Pressure, action of, 79, 131
Prolith, 280
Protoplasm, 280
Quetelet, 262
Q
Rain, 298
Rarefaction, action of, 125, 131
139, 246
Rayleigh, 112, 299
Rays, xxx, xxxi, xxxii, 83, 201
Residual charge, 184
Resistance, xv, 7, 33, 72, 79
and heat, 72, 111
increased by alloy, 92, 114
of fluids, 117
of gases, 117
-of solids, 112,114
of wire conductors, 110, 112
Resonator, 240
Return shock, 149, 307
Richmann, 258
Righi,239,242,294
Rontgen, 246, 250, 252
Saussure, 283
Schuster, 77, 301
Sebeck, 62
348
INDEX
Selenium, 67, 75, 98
S. force, 65
Shackleton, 268
Smoke, conduction by, 77, 302
Spark discharge positive and nega-
tive, 135
oscillating, 166. 182, 239. 305
size of, 131, 141, 310
Static electricity, vii, viii, 34, 141
Stationary waves, 138, 162, 171,
226
Steam electric engine, 57, 202
St. Elmo's fire, xxxvi, 125
Storage, xxiv, 167, 176
Strain, 29, 153, 182, 190, 216, 225,
307
Striae, 138
Submarine cables, 181
Sun, 265, 278, 326, 330, 332
and electricity, 16
rays, 321, 326, 329
Surfaces of fluids, 107
of solid conductors, 90, 98, 104
Tait, 157
Thermoelectric force S., 64
potential, 71
welding, 72
Thermoelectricity, ix, x
Thermopile, 41, 62
Thompson, Silvanus, 36, 66, 78
Thomson effect, 64
Thunder, 309
Torpedo, 312
Torricellian vacuum, 138
Tourmaline, 74, 76
Transparency, 244, 252
Trowbridge, 226
Two electricities, 224, 228
U
Ultra-violet light, 77, 200, 235
Vacuum, 77, 130
tubes, 105, 137, 246, 249, 277
chemical action in, 82
conduct on surface, 84
Vanderfliet, 154, 210
Volcanic electricity, 60
Volt, 301
Voltaic action in thermoelectricity,
76
cell, 3, 6, 9, 17, 19, 24, 193, 217,
224
of one metal, 12
cells, arrangement of, 32
electricity, ii, iii, iv, v, vi, 142
- pile, 39, 217, 225
Volta's theory, 39
W
Water as conductor, 88
composition of, 8, 29, 218
decomposition of, 7
drops and electricity, 237, 299
skin, 107, 236, 298
vapour, 192, 297
Weather, 256, 296
Wheatstone's revolving mirror,
128, 139
Whetham, 9
Wiedman's rays, 254
Wilson, 83
Wire screens, 154
Wollaston, 54
X rays, 250
Zamboni, 39
Zeeman effect, 218
Zodiacal nebula, 319, 321, 325,
326
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