PROGRESS OF ELECTRICAL THEORY. 25 



the Huid in B and repels the matter in B with equal 

 energy, we have the resulting mutual inactivity of 

 the two bodies explained ; but without the latter 

 supposition, there would be a mutual attraction : 

 or we may put the proof more simply thus ; two 

 negatively electrized bodies repel each other; if 

 negative electrization were merely the abstraction 

 of the fluid which is the repulsive element, this 

 result could not follow except there were a repul- 

 sion in the bodies themselves, independent of the 

 fluid. And thus ^Epinus found himself compelled 

 to assume this mutual repulsion of material par- 

 ticles ; he had, in fact, the alternative of this sup- 

 position, or that of two fluids, to choose between, 

 for the mathematical results of both hypotheses are 

 the same. Wilcke, a Swede, who had at first as- 

 serted and worked out the ^Epinian theory in its 

 original form, afterwards inclined to the opinion 

 of Symmer ; and Coulomb, when, at a later period, 

 he confirmed the theory by his experiments and 

 determined the law of force, did not hesitate to 

 prefer 6 the theory of two fluids, "because," he says, 

 "it appears to me contradictory to admit at the 

 same time, in the particles of bodies, an attractive 

 force in the inverse ratio of the squares of the dis- 

 tances, which is demonstrated by universal gravi- 

 tation, and a repulsive force in the same inverse 

 ratio of the squares of the distances ; a force which 

 would necessarily be infinitely great relatively to 

 6 Mem. Ac. P. 178, p. 071. 



