Two kinds of 

 electricity. 



This new 

 agent. 



Franklin's 

 thi^ory. 



exposed to 

 strong objec- 



till TemovfcJ 

 hy Volta. 



ELECTRIC EFFECTS OF FRICTION* 



The greatest effect o^ friction before observed baviiij^ 

 been produced by resinous hodiest globes were made of 

 them, especially of sulphur, for electric machines, at the 

 same time us globes of g/aw, and they both produced the 

 divergence of pairs of balls ; but it was soon observed, that 

 the divergence produced by one kind of globe was destroyed 

 by the other kind : whence arose the system of two kinds 

 o? electricity, wh\ch were supposed to neutralize each other 

 when united, and to be manifested only when separated, 

 producing then their peculiar etftcts; one of them was called 

 vitreous and the other resinous. 



This new object of study engrossed the attention of all 

 natural philosophers, not only on its own account, but be- 

 cause of the deficiency of known agents in a great nutnber 

 of natural phenomena ; and thisr interest having been in- 

 creased, when the analogy between lightning and some of 

 the effects produced by the electric machine was discovered, 

 no wonder that many hasty systems were formed for ap- 

 plying this new, but undetermined agent, to various phe- 

 nomena not yet satisfactorily explained, even to the motions 

 of celestial bodies. 



The idea of two different electricities continued predo- 

 minant among natural philosophers, till Dr. Franklin ex- 

 plained the difference Vjetween the electric phenomena at- 

 tributed to this double cause by only more or less {plus or 

 mims) of the same fluid : but as this ingenious experimental 

 philosopher assigned the intermediate state between p/w* and 

 minus to a certain quantity/ of electric Jiuid belonging to 

 bodies, his theory, though adopted by the majority of elec- 

 tricians, remained subject to insuperable (jbjections under 

 this form ; which objections nobody more forcibly urged 

 than Dr. Peart, to whom no solid answer has been niatJe, 

 nor could be made, as long as the theory remained on the 

 haine foundation. Thus many experimental philosophers 

 have retained the idea of two distinct ^wif/*, as producing 

 thei-e two effects which destroy each other: but different 

 hypotheses have been framed on the nature of these fluids, 

 which have been even transformed into certain properties 

 belonging to bodies. However the duration of this variety 

 of systemii proceeds only from a want of attei>tion to the 



complete 



