on the Elearophorus, 1041 
near a prime conductor, will receive no electricity, or al- 
moft none, at the fame diltance as that at which a piece of 
metal or another conducting fubftance will have received 
a confiderable degree of electricity, or even a full fpark. 
The fecond part of this inherent quality may be thus 
demonftrated : a piece of metal infulated, as, for inftance, 
the metal plate of an ele&rophore, placed upon the cake 
of relin excited with a confiderable degree of electricity, 
will not receive any electricity at all, or only a faint one, 
when it is feparated from the cake without having been 
touched when it was in contact with the cake, or in the 
Iphere of aCtion of the cake, though it was really in a 
ftate of aCtual electricity all the time it was upon the 
plate. Now, if the cake of refin did part as eafily with 
its ftate of electricity as the metal plate, it would leave 
a confiderable degree of electricity upon the metal plate; 
the more as it is well known that the metal does not 
at all refill the receiving of it. 
Though it would be perhaps in vain to attempt a far- 
ther explanation of this inherent quality of non-con- 
duCting bodies, yet it will be eafy to illuftrate this law of 
nature by an example of another inherent quality in all 
matter, which Sir Isaac newton calls the vis inertia ; 
and is a vis injit a, by which matter refills being put in mo- 
tion, and when it is once put in motion requires as much 
Vol. LXV 1 IL 6 O force 
