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]