Experimental investigation of the spirit manifestations, [electronic ...

APPENDIX. 439Ohjcctions to the Theories severally of Frnnldinj Dufai/j and Ampere,with an effort to cjphiiii Eleetrieal Phenomena, hij Sfatieal or Undnlatori/Pofarir.ation.* Bij llohert JTare, M.D., Emeritus Professor ofChanisfry in the University of Pennsylvania.1. Tt appears, from the experiments of Whcatstone, that the dischargeof a Leydcn jar, by means of a copper wire, takes place witliin a lime sosmall, that were the transfer of a iluid from the positive to the negativesurface requisite for its accomi3lishment, a current having a velocity exceedingtwo hundred thousand miles in a second would be necessary.2. The only causes for the velocity of an electric current, according toFranklin, are the repulsion between the particles of the electric fluid ofwhich it has been assumed to consist, and the attraction between those particlesand other matter. These forces are alleged to concur in distributingthe supposed fluid throughout space, whether otherwise void, or partiallyoccupied by conducting solids or fluids. Hence, when between two ormore spaces, surfaces, or conducting masses, there is an unequal distributionof the electric fluid, the equilibrium is restored whenever a communicationis opened by means of a sufficiently conducting medium. Agreeablyto this view of the subject, there seems to be a resemblance between thesupposed eftbrt 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 anygas, there seems to be an analogy as respects the processes of diflusionwhich must prevail. But on opening a communication between cavitiesin which any aeriform fluid exists, in different degrees of condensation,the density must lessen in one cavity and augment in the other, with arapidity which must diminish gradually, and become evanescent with thedifference of pressure by which it is induced. Far from taking place inan analogous manner, electrical discharges are effected with an extremesuddenness, the whole of the redundancy being discharged at once, ina 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 aminimum.3. So far, in fact, is an electrical discharge from displaying the featureswhich belong to the reaction of a condensed elastic fluid, that agreeably tothe observations of our distinguished countryman Henry, the result is morelike the vibrations of a spring, which, in striving to regain its normal position,goes beyond it. The first discharge between the surfaces of aLeyden jar is not productive of a perfect cc^uilibrium. The transfer of•••According to Farraday's researches and general experience, we have reason to believethat all particles of matter are endowed with one or the other of two species of polarity.This word polarity conveys the idea that two terminations in each particle are respectivelyendowed with forces which are analogous, hut contrary in their nature; so that of any twohomogeneous particles, the similar poles repel each other, while the dissimilar attract;likewise, when freely suspended, they take a certain position relatively to each other, andon due proximity-, the opposite polar forces, counteracting each other, appear to be extinct.When deranged from this natural state of reciprocal neutralization, their liberated polesreact with the particles of adjacent bodies, or those in the surrounding medium. Underthese circumstances, any body Avhich may be constituted of the particles thus reacting issaid to be polarized, or in a state of polarization.Statical implies stationary; undulatory, wave-like.