PROGRESS OF ELECTRICAL THEORY. 211 



the hypothesis of two fluids lias been spoken of as a reform of the 

 theory of JEpinus ; it would probably have been more safe to have 

 called his labors an advance in the calculation, and in the comparison 

 of hypothesis with experiment, than to have used language which im- 

 plied that the question, between the rival hypotheses of one or two 

 fluids, could be treated as settled. For, in reality, if we assume, as 

 ^Epinus does, the mutual repulsion of all the particles of matter, in 

 addition to the repiilsion of the particles of the electric fluid for one 

 another and their attraction for the particles of matter, the one fluid 

 of JEpinus will give exactly the same results as the two fluids of Cou- 

 lomb. The mathematical formulas of Coulomb and of Poisson ex- 

 press the conditions of the one case as well as of the other ; the 

 interpretation only being somewhat different. The place of the forces 

 of the resinous fluid is supplied by the excess of the forces ascribed to 

 the matter above the forces of the fluid, in the parts where the electric 

 fluid is deficient. 



The obvious argument against this hypothesis is, that we ascribe to 

 the particles of matter a mutual repulsion, in addition to the mutual 

 attraction of universal gravitation, and that this appears incongruous. 

 Accordingly, ^Epinus says, that when he was first driven to this pro- 

 position it horrified him. 15 But we may answer it in this way very 

 satisfactorily : If we suppose the mutual repulsion of matter to be 

 somewhat less than the mutual attraction of matter and electric fluid, 

 it will follow, as a consequence of the hypothesis, that besides all 

 obvious electrical action, the particles of matter would attract each 

 other with forces varying inversely as the square of the distance. 

 Thus gravitation itself becomes an electrical phenomenon, arising from 

 the residual excess of attraction over repulsion ; and the fact which is 

 urged against the hypothesis becomes a confirmation of it. By this 

 consideration the prerogative of simplicity passes over to the side of 

 the hypothesis of one fluid ; and the rival view appears to lose at least 

 all its superiority. 



Very recently, M. Mosotti 10 has calculated the results of the .'Epinian 

 theory in a far more complete manner than had previously been per- 

 formed ; using Laplace's coefficients, as Poisson had done for the Cou- 



15 Xeque diffiteor curu ipsa se milii offerret . . . . meadipsam quoJammodc 

 exhorruisse. Tentamen Theor. Elect, p. SO. 



16 Sur Ics Forces qul rtyixseiit la Constitution Intiricitre dcs Corps. Turin. 

 1836. 



