IJLE6TRICAL EFFECTS PRODUCED BY FRICTION. ^OJ 



was made poskive. ^nt in Exper. 6, the same brass rubber 

 being applied to a revolving cylinder of sealing wax, the iatier 

 was made negative, and the Orass became positive. Thus, 

 therefore, brass, though the best conductor as a metal, when it 

 isinsulated, and thus retains the effect produced on it by /nc- 

 tion, shows, that it is rendered either positive or negative, 

 according to the body which exercises friction upon it. 



15. With respect to seali?ig wax, which is our common test Sealing was 



to discover whether our electroscopes indicate the positive or rendered posi- 



tive DV fric* 

 negative state by their divergence ; because staling wax, when tlon with cer- 



rubbed with the hand, or some cloth, becomes negative; ^a'" bodies. 



exper. 7 proves, that sealing wax itself is made positive by 



friction with certain bodies. In this experiment, the same 



revolving cylinder of sealing wax, which before was become 



negative by a Irass rubber, was made strongly positive by the 



India-rubber. 



16. Exper. 8 is farther illustrative of these differences of Other experi- 

 electrical effects produced by friction on the same bodies, ac- "^^nts show- 

 cording to those which exercise friction on them. The object effects on the 

 of that experiment is one of the India-beads, the size and *^™* bodies, 

 colour of a cherry, used by Indian women in necklaces or 



other ornaments, which consist of an inspissated vegetable oil. 

 One of these beads I made to revolve by a glass axis, and 

 applied to it successively a brass rubber, and a sealing wax one : 

 the brass rubber rendered it negative, and became itself posi- 

 tive ; but the sealing wax rubber made the same bead positive, 

 becoming itself negative. 



iQ. All these experiments prove, first, that the distinction Deductions 

 between electric and anelectric bodies was illusory j that none, 1°^^^^^^ **' 

 in their natural state, are either positive or negative. With 

 respect to friction, these experiments demonstrate, that this 

 operation has no other effect than that of disturbing the equili- 

 Irium of the electric fluid on their surface, one of which, 

 according to circumstances, retains more and the other less of 

 that fluid. 



17. If Dr. Maycock happens to see this abstract of the ex- 

 periments contained in my former papers in your Journal, I 

 think he may find, that every thing belonging to electrical 

 phanomena is much clearer than he had imagined : he, however, 

 encouraged natural philosophers to collect all the known facts 



under 



