egi On the Pk(snomencL of the Electrophonis. 



of attraction and repulsion, while they are in contact with 

 conductiiig substances ; which is the reason why the upper 

 plale, i. e. the cover, exhibits no sign^ of electricity while 

 it remains in contact with the under one, though they be- 

 come sensible the instant it is removed from it." 



If any one can understand or apply this confusion of 

 ideas to elucidate the point in quebtion, he must possess a 

 larger portion of skill than I can pretend to claim. M. 

 Cavalio observes, (Complete Treaiisc, vol. ii. p. 35.) that 

 if the cake be accurately insulated, ;he cover acquires so 

 little electricity that it can only be detected bv the electro- 

 meter. This, however, as the editor of the Enctjclopcedia 

 Bntanvica observes, is manifestly untrue ; and it is diffi- 

 cult to imagine how so great a mistake should have oc- 

 curred. 



Other experiments mentioned by M. Cavalio accord 

 with No. I, 4, and 5, in imposing the cover, the sole 

 electrometer before diverging with negative electricity closes, 

 but again becomes negative. Comparing this with No. 9, 

 it will appear to be correct, but not to represent the whole 

 truth. In the results of No. 12 and 13, I am also con- 

 firnjed by Cavalio. The theory of this author is comprised 

 in a short compass, and, I believe, is not tar wide fro^i the 

 truth : it does not, however, include the whole of the phse- 

 iiomena, and requires a more detailed application. He says, 

 *' the action of these places depends upon a principle long 

 ago discovered, viz. the power of an excited electric to 

 induce a contrary electricity in a body brought within its 

 sphere of action. The metal plate therefore, when set upon 

 the excited electric, acquires a contrary electricity by giving 

 its electric fluid to the hand or other conductor, which 

 touches it when set upon a plate electrified positive, or ac- 

 quiring an additional quantity from the hand when upon a 

 plate electrified negative." It is not, however, true, that a 

 conductor in contact with an excited electric exhibits, while 

 in contact, signs of the opposite electricity. The general 

 appearances are thus recited and arranged in the Supplement 

 to the Encydopced'ui BriUinnica, article Electricity. 



*•' 1. IF the sole has been insulated during the congela- 

 tion of the c^lectric [i. e. where the cake is melted into the 

 sole and permanently annexed to it,) till all is cold and 

 hard, the whole is found negatively electric, and the finger 

 draws a spark from it, especially from the sole. If allowed 

 to remain in this situation its electric; .v grows gradually 

 weaker, and at last disappears; but ii may be again excited 

 by friction. If the cover be now imposed by its insulating 



handle. 



