feLECTRiC EFFECT? OF FEfCTiOM, J^ 



Complete solution of all the difficulties, which occurred in 

 the system of plus and minus, given by Sjg* Volta, in fixing 

 the real point to which ihesa po»itive and negative quantities 

 are to be referred, namely, the actual, but different at dif* 

 ferent times, electric state of the ambient air. 



According therefore to this system, all the electric phe- Only one elw 

 nomena are produced by one Jluid, the modifications of ^''ic ^"id. 

 which in terrestrial phenomena deserve the most attentive 

 and assiduous study of all experimental philosophers: but 

 oo agreement among them, either on the importance of 

 this study, or on the mode of its pursuit, can be expected^ 

 as long as they shall be so far divided in their opinions pn 

 the nature of this agent, as to leave a doubt whether it con- 

 sists of one and the same, or two distinct Jluids, or even of 

 some properties of bodies. 



Friction between bodies being the only method, hitherto txperiments 



known, by which can be produced at will the two kinds of °"/^^.^^^" 



,./,,,,, ,. , offnction. 



electric signs, 1 thought tijat the most direct and sure me- 

 thod of coming to a better knowledge of their meaning was 

 to study them at the origin of the two distinct phenomena ; 

 and I undertook a series of experiments on the effects of 

 ^ric/io« between various kinds of bodies; insulating those 

 which are more or less conductors, and Qpp\y\i\^ electroscopes 

 to both the bodies which exercised friction on each other; 

 in order to observe the modifications thus produced, not 

 only on the nonconducting, but on the conducting bodies, 

 I made these experiments with large apparatusses, by which 

 the reciprocal effects o^ friction between various bodies were 

 manifested by the motions of pairs of balls ; and from them 

 1 derived, without exception, the theory which I shall first 

 explain, and then prove by an account of some of the prin- 

 cipal experiments* 



I; The electric fluid resides on all terrestrial bodies, ever^"^ Theory. 



particle of air included; beino- retained upon them bv a ^°P'^"'^*'"^ 

 , i/v. • and noncoa* 



mutual attraction, which however differs in degree, accord- duciors. 



ing to the bodies : some attract the e/fc/nc^Hirf only when 



it comes into contact with them, but then it adheres strongly 



to the parts wliich receive it, moving very slowly along the 



surface of these bodies,* which therefore are nonconductors: 



others receive it at more or less distance, and it is propa- 



