Hare on Electricity. 103 



PHYSICS, CHEMISTRY, &c. 



Art. XII. — ^n Essay on the Question, whether there be 

 two Electrical Fluids, according to Du Faye, or one, ac- 

 cording to Franklin. By Robert Hare, M. D. Profes- 

 sor of Chemistry in the University of Pennsylvania. 



By those who allege the existence of two electrical fluids, 

 much stress has been laid on the fact, that light bodies, 

 when negatively electrified, separate from each other no lesSj 

 than when in the opposite state. The absence and pres- 

 ence of a fluid, cannot, it is said, have the same effect of 

 producing repulsion. To this, it has been answered, that 

 the separation of such light bodies is not the effect of repul- 

 sion, but of an attraction between them and the surround- 

 ing medium ; which must equally ensue, whether they be 

 electrified minus or plus ; since, in either case, that diver- 

 sity of electrical excitement between them and the sur- 

 rounding medium, arises, which is always productive of at- 

 traction. 



In support of this view of the question, I propose to make 

 a few observations. In an electroscope with moveable 

 coatings, like the galvanometer of Mr. Pepys,* the diver- 

 gence of the leaves is facilitated, in proportion as the coat- 

 ings are approximated to them. In this case, it must be 

 admitted, that there is an attraction between the coatings 

 and the leaves ; for, were repulsion between the leaves the 

 cause of their divergence, the approach of the coatings 

 would not increase it. 



It may, however, be supposed, that the repulsion be- 

 tween the similarly excited leaves, being counterbalanced, 

 more or less, in all cases, by the electric tension of the sur- 

 rounding medium, the coatings may permit the electric fluid 

 to recede through them with greater facility ; and thus les- 

 sen the electric tension, in the direction in which they are 

 situated. 



Were this supposition to avail in the case of an electro- 

 meter with two leaves, it cannot apply in the case of an in- 



* free Tilloch's Philosophical Magazine, vol. x. p. 38. 



