new Experiments in Ele&ricity , Sic. 17 
words, the powder of rofin will be attracted by thofe 
parts only of the eleCtrophorus, which are electrified 
pofitively. 
When I firit obferved thefe phenomena, I thought 
that there was no apparent reafon why the powder of 
rofin fliould be attracted by thofe parts of the eleCtro- 
phorus, which are in a pofitive ftate of electricity, and 
not by thofe, which are negative. The two electri- 
cities are certainly contrary to one another; but 
either of them attracts a non-eleCtrified body. On this 
confideration I thought, that the experiment could be 
explained only upon the fuppofition, that the powder of 
rofin, on its falling from the linnen bag, was actually 
eledtrified negatively; in which cafe it would have been 
eafy to account for the phenomena upon the well known 
principle of bodies attracting each other when they are 
contrarily electrified; and repelling one another when 
they are poffeffed of the fame kind of electricity. 
In order to try the reality of my fuppofition by expe- 
riments, I infulated a brafs plate upon a glafs Hand, and 
connected a very fenfible electrometer with it ; and then 
began fhaking the powder of rofin upon it, in the fame 
manner as I had done upon the eleCtrophorus, and in a 
few feconds of time had the pleafure to fee the eleCtro- 
Vol. LXX. D meter 
