_Speculation touching Electric Conduction and the nature of Matter. By
Farraday._
Having expressed my objections to Farraday’s inferences respecting
matter, &c., I feel that justice requires that I should submit the
article which drew forth my strictures. At this time, when electricity
and matter are scrutinized with a view to understand the analogous, but
different, entities of the spirit world, the ideas of an experimental
investigator so eminently successful, must be of interest to readers:
Light and electricity are two great and searching investigators of
the molecular structure of bodies, and it was, while considering
the probable nature of conduction and insulation in bodies not
decomposable by the electricity to which they were subject, and the
relation of electricity to space contemplated as void of that which,
by the anatomist, is called matter, that considerations, something
like those which follow, were presented to my mind.
If the view of the constitution of matter, already referred to, be
assumed to be correct, and I may be allowed to speak of the particles
of matter and of the space between them (in water, or in the vapour
of water, for instance) as two different things, then space must be
taken as the only continuous part, for the particles are considered as
separated by space from each other. Space will permeate all masses of
matter in every direction like a net, except that, in place of meshes,
it will form cells, isolating each atom from its neighbours, and
itself only being continuous.
Then take the case of a piece of shellac, a non-conductor, and it
would appear at once, from such a view of its constitution, that
space is an insulator, for if it were a conductor, the shellac could
not insulate, whatever might be the relation as to conducting power
of its material atoms; the space would be like a fine metallic web
penetrating it in every direction, just as we may imagine of a heap
of siliceous sand having all its pores filled with water, or as we
may consider of a stick of black wax, which, though it contains an
infinity of particles of conducting charcoal diffused through every
part of it, cannot conduct, because a non-conducting body (a resin)
intervenes and separates them one from another like the supposed space
in the lac.
Next take the case of a metal, platinum or potassium, constituted,
according to the atomic theory, in the same manner. The metal is a
conductor; but how can this be, except space be a conductor, for it
is the only continuous part of the metal, and the atoms not only do
not touch, (by the theory,) but, as we shall see presently, must be
assumed to be a considerable way apart. Space, therefore, must be a
conductor, or else the metals could not conduct, but would be in the
situation of the black sealing-wax referred to a little while ago.
But if space be a conductor, how then can shellac, sulphur, &c.
insulate? for space permeates them in every direction. Or, if space be
an insulator, how can a metal or other similar body conduct?
It would seem, therefore, that in accepting the ordinary atomic
theory, space may be proved to be a non-conductor in non-conducting
bodies, and a conductor in conducting bodies; but the reasoning
ends in this, a subversion of that theory altogether, for if space
be an insulator, it cannot exist in conducting bodies, and if it be
a conductor, it cannot exist in insulating bodies. Any ground of
reasoning which tends to such conclusions must in itself be false.
In connection with such conclusions, we may consider shortly what
are the probabilities that present themselves to the mind, if the
extension of the atomic theory which chemists have imagined be applied
in conjunction with the conducting powers of metals. If the specific
gravity of the metals be divided by the atomic numbers, it gives
us the number of atoms, upon the hypothesis, in equal bulks of the
metals. In the following table the first column of figures expresses
nearly the numbers of atoms in, and the second column of figures the
conducting power of, equal volumes of the metals named:
Atoms. Conducting power.
1·00 gold 6·00
1·00 silver 4·66
1·12 lead 0·52
1·30 tin 1·00
2·20 platinum 1·04
2·27 zinc 1·80
2·87 copper 6·33
2·90 iron 1·00
So here iron, which contains the greatest number of atoms in a given
bulk, is the worst conductor excepting one. Gold, which contains the
fewest, is nearly the best conductor; not that these conditions are in
inverse proportions, for copper, which contains nearly as many atoms
as iron, conducts better still than gold, and with above six times the
power of iron. Lead, which contains more atoms than gold, has only
about one-twelfth of its conducting power; lead, which is much heavier
than tin and much lighter than platina, has only half the conducting
power of either of these metals. And all this happens among substances
which we are bound to consider at present as elementary or simple.
Whichever way we consider the particles of matter and the space
between them, and examine the assumed constitution of matter by this
table, the results are full of perplexity.
Now let us take the case of potassium, a compact metallic substance
with excellent conducting powers—its oxide or hydrate a non-conductor;
it will supply us with some facts having very important bearings on
the assumed atomic construction of matter.
When potassium is oxidized, an atom of it combines with an atom of
oxygen to form an atom of potassa, and an atom of potassa combines
with an atom of water, consisting of two atoms of oxygen and hydrogen,
to form an atom of hydrate of potassa, so that an atom of hydrate
of potassa contains four elementary atoms. The specific gravity of
potassium is 0·865, and its atomic weight 40·; the specific gravity
of cast hydrate of potassa, in such a state of purity as I could
obtain it, I found to be nearly 2; its atomic weight, 57. From these,
which may be taken as facts, the following strange conclusions flow:
A piece of potassium contains less potassium than an equal piece of
the potash formed by it and oxygen. We may cast into potassium oxygen,
atom for atom, and then again both oxygen and hydrogen in a twofold
number of atoms, and with all these additions the matter shall become
less and less, until it is not two-thirds of its original volume. If
a given bulk of potassium contains 45 atoms, the same bulk of hydrate
of potassa contains 70 atoms nearly _of the metal potassium_, and,
besides that, 210 atoms more of oxygen and hydrogen. In dealing with
assumptions, I must assume a little more for the sake of making any
kind of statement; let me therefore assume that in the hydrate of
potassa the atoms are all of one size and nearly touching each other,
and that in a cubic inch of that substance there are 2800 elementary
atoms of potassium, oxygen, and hydrogen; take 2100 atoms of oxygen
and hydrogen, and the 700 atoms of potassium remaining will swell
into more than a cubic inch and a half; and if we diminish the number
until only those containable in a cubic inch remain, we shall have
430, or thereabout. So a space which can contain 2800 atoms, and
among them 700 of potassium itself, is found to be entirely filled by
430 atoms of potassium, as they exist in the ordinary state of that
metal. Surely, then, under the suppositions of the atomic theory, the
atoms of potassium must be very far apart in the metal, _i. e._ there
must be much more of space than of matter in that body; yet it is an
excellent conductor; and so space must be a conductor, but then what
becomes of shellac, sulphur, and all the insulators? for space must
also, by the theory, exist in them.
Again, the volume which will contain 430 atoms of potassium, and
nothing else while in the state of metal, will, when that potassium
is converted into nitre, contain very nearly the same number of atoms
of potassium, _i. e._ 416, and also then seven times as many, or 2912
atoms, of nitrogen and oxygen beside. In carbonate of potassa, the
space which will contain only the 430 atoms of potassium as metal,
being entirely filled by it, will, after the conversion, contain
256 atoms more of potassium, making 686 atoms of that metal, and in
addition 2744 atoms of oxygen and carbon.
These and similar considerations might be extended through compounds
of sodium and other bodies, with results equally striking, and indeed
more so, when the relations of one substance, as oxygen and sulphur,
with different bodies are brought into comparison.
I am not ignorant that the mind is most powerfully drawn by the
phenomena of crystallization, chemistry, and physics generally to the
acknowledgment of centres of force. I feel myself constrained, for the
present, hypothetically to admit them, and cannot do without them; but
I feel great difficulty in the conception of atoms of matter which in
solids, fluids, and vapours are supposed to be more or less apart from
each other, with intervening space not occupied by atoms, and perceive
great contradictions in the conclusions which flow from such a view.
If we must assume at all, as indeed in a branch of knowledge like
the present we can hardly help it, then the safest course appears to
be to assume as little as possible; and in that respect the atoms of
Boscovich appear to me to have a great advantage over the more usual
notion. His atoms, if I understand aright, are mere centres of forces
or powers, not particles of matter in which the powers themselves
reside. If in the ordinary view of atoms, we call the particle of
matter away from the powers _a_, and the system of powers or forces in
and around it _m_, then in Boscovich’s theory _a_ disappears, and is
a mere mathematical point, while in the usual notion it is a little,
unchangeable, impenetrable piece of matter, and _m_ is an atmosphere
of force grouped around it.
In many of the hypothetical uses made of atoms, as in crystallography,
chemistry, magnetism, &c., this difference in the assumption makes
little or no alteration in the results; but in other cases, as of
electric conductors, the nature of light, the manner in which bodies
combine to produce compounds, the effect of forces, as heat or
electricity, upon matter, the difference will be very great.
Thus, referring back to potassium, in which as a metal the atoms must,
as we have seen, be, according to the usual view, very far apart
from each other, how can we for a moment imagine that its conducting
property belongs to it any otherwise than as a consequence of the
properties of the space, or, as I have called it above, the _m_?
So also its other properties in regard to light, or magnetism, or
solidity, or hardness, or specific gravity, must belong to it, in
consequence of the properties or forces of the _m_, not those of the
_a_, which, without the forces, is conceived of as having no powers.
But then, surely, the _m_ is the _matter_ of the potassium, for
where is there the least ground (except in a gratuitous assumption)
for imagining a difference in kind between the nature of that space
midway between the centres of two contiguous atoms, and any other spot
between these centres? A difference in degree or even in the nature
of the power consistent with the laws of continuity I can admit, but
the difference between a supposed little hard particle and the powers
around it, I cannot imagine.
To my mind, therefore, the _a_ or nucleus vanishes, and the substance
consist of the powers or _m_; and indeed what notion can we form
of the nucleus independent of its powers? All our perception and
knowledge of the atom, and even our fancy, is limited to ideas of its
powers; what thought remains on which to hang the imagination of an
_a_ independent of the acknowledged forces? As mind just entering on
the subject may consider it difficult to think of the powers of matter
independent of a separate something to be called _the matter_, but it
is certainly far more difficult, and indeed impossible to think of or
imagine that _matter_ independent of the powers. Now, the powers we
know and recognise in every phenomena of the creation, the abstract
matter in one; why, then, assume the existence of that of which we
are ignorant, which we cannot conceive, and for which there is no
philosophical necessity?
Before concluding these speculations, I will refer to a few of the
important differences between the assumption of atoms consisting
merely of centres of force like those of Boscovich, and that other
assumption of molecules of something specially material, having powers
attached in and around them.
With the latter atoms a mass of matter consists of atoms and
intervening space; with the former atoms matter is everywhere present,
and there is no intervening space unoccupied by it. In gases the atoms
touch each other just as truly as in solids. In this respect the atoms
of water touch each other, whether that substance be in the form of
ice, water, or steam; no mere intervening space is present. Doubtless,
the centres of force vary in their distance one from another, but
that which is truly the matter of one atom touches the matter of its
neighbours.
Hence matter will be _continuous_ throughout, and in considering
we have not to suppose a distinction between its atoms and any
intervening space. The powers around the centres give these centres
the properties of atoms of matter; and these powers again, when many
centres by their conjoint forces are grouped into a mass, give to
every part of that mass the properties of matter. In such a view
all the contradiction resulting from the consideration of electric
insulation and conduction disappears.
The atoms may be conceived of as highly _elastic_, instead of
being supposed excessively hard and unalterable in form; the mere
compression of a bladder of air between the hands can alter their size
a little, and the experiments of Cagniard la Tour carry on this change
in size until the difference in bulk at one time and another may be
made several hundred times. Such is also the case when a solid or a
fluid body is converted into vapour.
With regard also to the _shape_ of the atoms, and, according to the
ordinary assumption, its definite and unalterable character, another
view must now be taken of it. An atom by itself might be conceived
of as spherical or spheroidal, or where many were touching in all
directions, the form might be thought of as a dodecahedron, for
any one would be surrounded by and bear against twelve others, on
different sides. But if an atom be conceived to be a centre of power,
that which is ordinarily referred to under the term _shape_, would
now be referred to the disposition and relative intensity of the
forces. The power arranged in and around a centre might be uniform in
arrangement and intensity in every direction outward from that centre,
and then a section of equal intensity of force through the radii would
be a sphere; or the law of decrease of force from the centre outward
might vary in different directions, and then the section of equal
intensity might be an oblate or oblong spheroid, or have other forms;
or the forces might be disposed so as to make the atom polar; or they
might circulate around it equatorially or otherwise, after the manner
of imagined magnetic atoms. In fact, nothing can be supposed of the
disposition of forces in or about a solid nucleus of matter, which
cannot be equally conceived with respect to a centre.
In the view of matter now sustained as the lesser assumption, matter
and the atoms of matter would be mutually penetrable. As regards
the mutual penetrability of matter, one would think that the facts
respecting potassium and its compounds, already described, would
be enough to prove that point to a mind which accepts a fact for a
fact, and is not obstructed in its judgment by preconceived notions.
With respect to the mutual penetrability of the atoms, it seems to
me to present in many points of view a more beautiful, yet equally
probable and philosophic, idea of the constitution of bodies than the
other hypotheses, especially in the case of chemical combination.
If we suppose an atom of oxygen and an atom of potassium about to
combine and produce potash, the hypothesis of solid, unchangeable,
impenetrable atoms places these two particles side by side in a
position easily, because mechanically, imagined, and not unfrequently
represented; but if these two atoms be centres of power, they will
mutually penetrate to the very centres, thus forming one atom or
molecule, with powers either uniformly around it or arranged as the
resultant of the powers of the two constituent atoms; and the manner
in which two or many centres of force may in this way combine, and
afterward, under the dominion of stronger forces, separate, may in
some degree be illustrated by the beautiful case of the conjunction
of two sea waves of different velocities into one, their perfect
union for a time, and final separation into the constituent waves,
considered, I think, at the meeting of the British Association at
Liverpool. It does not, of course, follow from this view that the
centres shall always coincide; that will depend upon the relative
disposition of the powers of each atom.
The view now stated of the constitution of matter would seem to
involve necessarily the conclusion that matter fills all space, or,
at least, all space to which gravitation extends, (including the sun
and its system,) for gravitation is a property of matter dependent on
a certain force, and it is this force which constitutes the matter.
In that view matter is not merely mutually penetrable, but each
atom extends, so to say, throughout the whole of the solar system,
yet always retaining its own centre of force. This, at first sight,
seems to fall in very harmoniously with Massotti’s mathematical
investigations and reference of the phenomena of electricity,
cohesion, gravitation, &c. to one force in matter, and also again with
the old adage “matter cannot act where it is not.” But it is no part
of my intention to enter into such considerations as these, or what
the bearings of this hypothesis would be on the theory of light and
the supposed ether. My desire has been rather to bring certain facts
from electrical conduction and chemical combination to bear strongly
upon our views regarding the nature of atoms and matter, and so to
assist in distinguishing in natural philosophy our real knowledge—_i.
e._ the knowledge of facts and laws—from that, which, though it has
the form of knowledge, may, from its including so much that is mere
assumption, be the very reverse.
It is to be regretted that the memoir of the Rev. Mr. Whewell could not
be quoted, being long and obscure. His opinions, it is conceived, have
been stated fairly, (1796.)
_Motives for republishing my Memoirs on Electrical Theory._
The principal motive, without which the other motives would not have
prevailed, is, that having had an interview with the spirit of Franklin
expressly to have his advice, it was given decidedly in favour of
publication.
There is no door in the temple of science which is so easy of access as
that which leads to the department of electricity. The illustrations
usually given at a popular lecture may, at the same time, amuse an
infant, instruct a student, and yet perplex a profound philosopher.
As associated with the phenomena of thunder and lightning, at one
time attributed to the bolt of omnipotent Jove, no consequences of
scientific research are so awful and sublime: coupled with the magnetic
electric telegraph, no other result so miraculous. While _vis inertiæ_
would keep all nature in _statu quo_, whether at rest, or like our
planet in motion with a velocity fifty times as great as that of a
cannon ball: while gravitation tends like the clock weight to produce a
definite action and, _per se_, never to act again: electricity, with a
protean diversity of power, appears to be the great instrument of all
those changes by which the quiescent influence of the properties above
mentioned, is modified in the mundane sphere of chemistry and of life.
Every tyro is aware of the wonderful property imparted to electrics by
friction—to the tourmaline by heat; and that the same process, on a
large scale, will produce sparks, ignition, combustion, deflagration,
and destroy animal life by an instantaneous shock. It is notorious that
these wonderful powers may all be imparted to a naked pane of glass,
while the charge thus imparted is really only two opposite and equal
affections, capable of neutralizing each other by due communication.
Known also is it, that properties, to a certain extent similar, may be
found in a pile of pairs of heterogeneous metals, with the additional
power of electrolysis, or, in other words, of resolving chemical
compounds into their ingredients, (1376.) It is well known that, by
these means, water, long and almost religiously considered as one of
the four elements of the universe, can be decomposed into two kinds of
air; that the earths and alkalies have been resolved into metals and
oxygen; and that there is scarcely any chemical compound consisting
of two elements, which may not, when in aqueous solution or in fusion
by heat, be directly or indirectly decomposed by electrolysis, as
explained in the note to page 384.
These multifarious feats of electricity have caused it to be
contemplated as the source of every thing mysterious in nature. It is
not surprising, therefore, that those who, through the accessibility of
electricity, had become partially acquainted with electrical phenomena,
should view it as the source of spiritual manifestations; while those
who have a more extensive knowledge of the nature and extent of
electrical jurisdiction should perceive at once that the phenomena in
question do not fall within its sphere.
After the discovery, by Oersted, of the previously unsuspected reaction
between galvanized wire and a magnetic needle, those who had resorted
to either one or two fluids to explain electrical phenomena, found
themselves completely at fault. Yet the language originated by Franklin
has been still employed conventionally. This, though not misleading
adepts, introduces confusion in the minds of those who have merely
reached the ante-chamber of the electrical department.
Under these circumstances, I deem it expedient to republish the
exposition of electrical theory which I first laid before the
scientific world in 1848.
I hope that those who endeavour to refer spiritual manifestations or
animal magnetism to electricity, in any of its modifications, will
study this exposition of my views.
Though, as already stated, there appears to be, for the spirit world,
appropriate elements, distinct from those of this mundane world,
there is, nevertheless, a correspondence. We mortals can best prepare
ourselves to understand the elements of that world by understanding our
own. From an idea of _our_ light and _our_ vital air, we may by analogy
conceive of theirs as a preliminary to any further knowledge.
The following theory has been submitted to the spirit of Franklin, who
fully approved of it, and fully admitted the validity of the reasons
assigned by me for substituting this new exposition of electricity for
that which goes under his celebrated name.
_Objections to the Theories severally of Franklin, Dufay, and Ampere,
with an effort to explain Electrical Phenomena, by Statical or
Undulatory Polarization.[58] By Robert Hare, M.D., Emeritus Professor
of Chemistry in the University of Pennsylvania._
1. It appears, from the experiments of Wheatstone, that the discharge
of a Leyden jar, by means of a copper wire, takes place within a time
so small, that were the transfer of a fluid from the positive to the
negative surface requisite for its accomplishment, a current having
a velocity exceeding two hundred thousand miles in a second would be
necessary.
2. The only causes for the velocity of an electric current, according
to Franklin, are the repulsion between the particles of the electric
fluid of which it has been assumed to consist, and the attraction
between those particles and other matter. These forces are alleged to
concur in distributing the supposed fluid throughout space, whether
otherwise void, or partially occupied by conducting solids or fluids.
Hence, when between two or more spaces, surfaces, or conducting
masses, there is an unequal distribution of the electric fluid, the
equilibrium is restored whenever a communication is opened by means
of a sufficiently conducting medium. Agreeably to this view of the
subject, there seems to be a resemblance between the supposed effort of
the electrical fluid to attain a state of equable diffusion, and that
which would exist in the case of a gas confined in adjoining receivers,
so as to be more dense within one than within the other; for, however
the subtilty of the supposed electric fluid may exceed that of any gas,
there seems to be an analogy as respects the processes of diffusion
which must prevail. But on opening a communication between cavities in
which any aeriform fluid exists, in different degrees of condensation,
the density must lessen in one cavity and augment in the other, with a
rapidity which must diminish gradually, and become evanescent with the
difference of pressure by which it is induced. Far from taking place in
an analogous manner, electrical discharges are effected with an extreme
suddenness, the whole of the redundancy being discharged at once,
in a mode more like the flight of a bullet, projected with infinite
velocity, than that of a jet gradually varying in celerity from a
maximum to a minimum.
3. So far, in fact, is an electrical discharge from displaying the
features which belong to the reaction of a condensed elastic fluid,
that agreeably to the observations of our distinguished countryman
Henry, the result is more like the vibrations of a spring, which, in
striving to regain its normal position, goes beyond it. The first
discharge between the surfaces of a Leyden jar is not productive of a
perfect equilibrium. The transfer of different polarities goes beyond
the point of reciprocal neutralization, producing a state, to a small
extent, the opposite of that at first existing; and hence a refluent
discharge ensues, opposite in direction to the primary one. But even
this does not produce an equilibrium, so that a third effort is made.
These alternate discharges were detected by means of the magnetism
imparted to needles exposed in coils of copper wire.[59]
4. Supposing one or more rows of electrical particles, forming such a
filament of electricity as must occupy the space within a wire of great
length, to be made the medium of discharge to a Leyden jar; agreeably
to the hypothesis of one fluid, the electrical filament must be
attracted at one end of the wire and repelled at the other, as soon as
its terminations are brought into due communication with the coatings
of the jar. Yet the influence of the oppositely-charged surfaces of the
jar cannot be conceived to extend to those portions of the electricity
which are remote from the points of contact, until they be reached
by a succession of vibrations. Hence, it is inconceivable that every
particle in the filament of electric matter can be made at the same
time to move, so as to constitute a current having the necessary
velocity and volume to transfer, instantaneously, the electricity
requisite to constitute a charge. Even the transmission of the
impulses, in such an infinitesimal of time, seems to be inconceivable.
5. In reply to these objections, it has been urged by the Franklinians
that a conductor being replete with electricity, as soon as this fluid
should be removed at one end, it ought to move at the other. This might
be true of a fluid if incompressible, but could not hold good were it
elastic. A bell wire moves at both ends when pulled only at one; but
this would not ensue were a cord of gum-elastic substituted for the
wire.
6. But if the flow of one fluid, with the enormous velocity inferred,
be difficult to conceive, still more must it be incomprehensible that
two fluids can rush with similar celerity, from each surface of the
jar, in opposite directions, through the narrow channel afforded by a
wire; especially as they are alleged to exercise an intense affinity;
so that it is only by a series of decompositions and recompositions
that they can pass each other.
7. That agreeably to the theory of Dufay, equivalent portions of the
resinous and vitreous fluids must exchange places during an electrical
discharge, will appear evident from the following considerations: One
surface being redundant with vitreous and deficient commensurately of
resinous electricity, and the other redundant with the resinous and
deficient of the vitreous fluid, it is inevitable that, to restore the
equilibrium, there must be a simultaneous transfer of each redundancy
to the surfaces wherein there is a deficiency of it to be supplied. If,
after decomposing a large portion of the neutral compound previously
existing on the surface of the jar, and transferring the ingredients
severally in opposite directions, so as to cause each to exist in
excess upon the surface assigned to it, should the redundancies, thus
originated, be neutralized by meeting in the discharging rod, neither
surface could recover its quota of the electrical ingredient of which
it must have been deprived agreeably to the premises.
8. This calls to mind the fact that no evidence has been adduced of the
existence of any _tertium quid_, arising from the union of the supposed
electricities, founded on any property displayed by their resulting
combination in the neutral state. It must, if it exist, constitute an
anomalous matter, destitute of all properties, and of the existence of
which we have no evidence, besides that founded on the appearance and
disappearance of its alleged ingredients.
9. But however plausibly the discharges consequent to making a
conducting communication from one electrified mass or surface to
another mass or surface in an opposite state, may be ascribed to
accumulations either of one or of two fluids, neither, according to
one theory nor the other, is it possible to account satisfactorily
for the stationary magnetism with which steel may be endowed, nor the
transitory magnetism, or power of dynamic induction, acquired by wires
transmitting galvanic discharges.
10. For the most plausible effort which has been made for the purpose
of reconciling the phenomena of electro-magnetism with the theory of
two fluids, or with that of one fluid so far as these theories are
convertible, we are indebted to Ampere.
11. According to the hypothesis advanced by this eminent philosopher,
the difference between a magnetized and an electrified body is not
attributable to any diversity in the imponderable matter to which
their properties are respectively due, but to a difference in the
actual state or distribution of that matter. Statical polarity is
the consequence of the unequal distribution of the two electric
fluids whose existence he assumes; while magnetical polarity is the
consequence merely of the motion of those fluids, which, in magnets,
are supposed to gyrate in opposite directions about each particle of
the mass. These gyrations are conceived to take place only in planes at
right angles to the axis of the magnet; so that, in a straight magnet,
the planes of the orbits must be parallel to each other.[60]
12. The aggregate effect of all the minute vortices of the electrical
fluids, in any one plane, bounded by the lateral surfaces of the
magnet, is equivalent externally to one vortex, since, in either
case, every electric particle on that surface will so move as to
describe tangents to a circle drawn about the axis of the magnet. When
the electrical vortices of the pole of one magnet conflict in their
direction with those of another, as when similar magnetic poles are
approximated, repulsion ensues; but if the vortices are coincident in
direction, as when dissimilar poles are near, attraction takes place.
When a current through a galvanized wire[61] concurs in direction with
the magnetic vortices, as above described, attraction ensues; repulsion
resulting when it does not so concur. Hence, the magnet, if movable,
will strive to assume a position in which its electrical currents
will not conflict with those of the wire on one side more than on the
other; also the wire, if movable, will strive so to arrange itself so
as to produce the same result, which can arrive only when the needle
is at right angles to the wire, and its sides consequently equidistant
therefrom.
13. Electric currents will produce magnetic vortices, and,
reciprocally, magnetic vortices will produce electric currents. Hence
the magnetism imparted to iron by galvanic spirals, and the Farradian
currents produced by magnetized iron within spirals not galvanized.
14. Ampere’s theory has, in a high degree, the usual fault of
substituting one mystery for another; but, on the other hand, it has,
in an equally high extent, the only merit to which any theory can make
an indisputable claim: I mean that of associating facts so as to make
them more easy to comprehend and to remember, enabling us, by analogy,
to foresee results, and thus affording a clue in our investigations.
Evidently, the author of this theory was guided by it in his highly
interesting and instructive contrivances; and Professor Henry ascribes
his success in improving the electro-magnet to the theoretic clue which
he had received from Ampere.
15. Nevertheless, the postulates on which this Amperean hypothesis
is founded appear to me unreasonable. They require us to concede
that about every atom of a permanent magnet a process is going on
analogous to that generally admitted to exist in a galvanic circuit,
where two fluids pass each other in a common channel by a series
of decompositions and recompositions, (7.) In the galvanic circuit
this process is sustained by chemical reaction; but without any
coenduring cause, how is it to be sustained permanently in a magnet?
Is it reasonable to assume that the heterogeneous constituents of an
imaginary _tertium quid_ are perpetually separating only to reunite?
(8.)[62]
16. In cases of complex affinity, where four particles, A B C D are
united into two compounds A B, C D, it is easy to conceive that, in
obedience to a stronger affinity, A shall combine with C, and B with
D: but, without any extraneous agency, wherefore, in any one compound,
should a particle A quit a particle B, in order to unite with another
particle of the same kind; or wherefore should any one B quit one A, in
order to combine with another A?
17. That such a process should take place in consequence of the
inductive agency of a similar process already established in a magnet
or galvanized wire were difficult to believe; but it would seem utterly
incredible that the most _transient_ influence of such induction should
be productive of such permanent electrolytic gyration as has been above
specified. Moreover, it is inconceivable that the particles of any
matter should, as required by this hypothesis, _merely by being put
into motion_, acquire a power of reciprocal repulsion or attraction of
which it were otherwise destitute.
18. The vortices being assumed to take place about each atom, cannot
severally occupy an area of greater diameter than can exist between the
centres of any two atoms. Of course, the gyratory force exercised about
the surface of a magnet by the aggregate movements of the vortices
cannot extend beyond the surface more than half the diameter of one
of the minute areas of gyration alluded to. Wherefore, then, do these
gyrations, when similar in direction, from their concurrence approach
each other; when dissimilar in direction, from contrariety move away,
even when situated comparatively at a great distance?
19. I should consider Ampere’s theory as more reasonable were it
founded upon the existence of one fluid; since, in that case, vortices
might be imagined without the necessity of supposing an endless and
unaccountable separation and reunion of two sets of particles; not only
devoid of any property capable of sustaining their alleged opposite
gyrations, but actually endowed with an intense reciprocal attraction
which must render such gyrations impossible. But even if grounded on
the idea of one fluid, this celebrated hypothesis does not seem to
me to account for the phenomena which it was intended to explain.
If distinct portions of any fluid do not attract or repel each other
when at rest, wherefore should they either attract or repel each other
when in motion? Evidently mere motion can generate neither attraction
nor repulsion. Bodies projected horizontally gravitate with the same
intensity, and consequently, in any given time, fall to the earth
through the same perpendicular distance, whether moving with the
celerity of a cannon ball, or undergoing no impulse excepting those
arising from their own unresisted weights.
20. The objections which are thus shown to be applicable in the case
of liquids, of which the neighbouring particles are destitute of the
reaction requisite to produce the phenomena requiring explanation,
must operate with still greater force where ethereal fluids are in
question, of which the properties are positively irreconcilable with
the phenomena. According both to Franklin and Dufay, bodies, when
similarly electrified, should repel each other; yet in point of fact,
collateral wires, when subjected to similar voltaic discharges, and of
course similarly electrified, become reciprocally attractive, while
such wires, when dissimilarly electrified by currents which are not
analogous, become reciprocally repulsive.
21. Agreeably to Ampere, an iron bar, situated within a coil of wire
subjected to a galvanic current, is magnetized, because the current in
the wire is productive of an electrical whirlpool about every particle
of the metal. When the iron is soft, the magnetism, and of course
the gyrations of which its magnetism consists by the premises, cease
for the most part as soon as the circuit through the coil is broken;
but when the iron is in the more rigid state of hardened steel, the
gyrations continue for any length of time after the exciting cause has
ceased.
22. This theory does not explain wherefore the hardening of the
steel should cause the gyration to be more difficult to induce, yet
more lasting when its induction is effected. Evidently the metallic
particles must take some part in the process; since it is dependent for
its existence and endurance upon their nature and their state. Yet no
function is assigned to these particles. In fact, it is inconceivable
either that they can participate in, or contribute to, the supposed
gyration.
23. The electrical fluid in an iron bar cannot form a vortex about
each particle, all the vortices turning in one direction, without a
conflict between those which are contiguous. In order not to conflict
with each other, the alternate vortices would have to turn in different
directions, like interlocking cog-wheels in machinery. But in that
case, if magnetism be due to currents, the magneto-inductive influence
of one set would neutralize that of the other. Again, how can a
current, excited by a battery in one circuitous conductor, cause, by
dynamic induction, a current in the _opposite direction_, through
another conductor parallel to the first, but insulated therefrom? How
can a current of quantity in a ribbon coil[63] give rise to one of
intensity in a coil of fine wire, rushing of course with a velocity
commensurate with the intensity thus imparted?
24. From the preceding considerations, and others which will be
stated, it follows that it has been erroneously inferred that the only
difference between galvanic and frictional electricity is dependent on
quantity and intensity. It must be evident that there is a diversity in
the nature of these affections of matter, sufficient to create a line
of demarcation between them.
25. Having stated my objections to the electrical theories heretofore
advanced, it may be proper that I should suggest any hypothetical
views which may appear to me of a character to amend or to supersede
those to which I have objected. But however I may have been emboldened
to point out defects which have appeared to me to be inherent in the
theories heretofore accredited, I am far from presuming to devise any
substitute which will be unobjectionable. I am fully aware that there
is an obscurity as respects the nature and mutual influence of chemical
affinity, heat, light, electricity, magnetism, and vitality, which
science can only to a minute extent dispel.
26. The hypothesis which I now deem preferable is so much indebted
to the researches and suggestions of Farraday and others, that, were
it true, I could claim for myself but a small share of the merit of
its origination. That sagacious electrician employs the following
language: “_In the long-continued course of experimental inquiry, in
which I have been engaged, this general result has pressed upon me
constantly—namely, the necessity of admitting two forces or directions
of force, combined with the impossibility of separating these two
forces or electricities from each other._” (_Experimental Researches_,
1163.)[64]
27. Subsequently, (1244,) after citing another proof of the
inseparability of the two electric forces, he alleges _it to be_
“_another argument in favour of the view that induction and its
concomitant phenomena depend upon_ a polarity of the particles of
matter!”
_Supposed grounds for a Theory._