C 3 l8 ] 
{lone into boiling water, and continued it there near 
one minute. On taking it out, and prefenting the 
convex Tide thereof near the pith balls, they immedi- 
ately receded from it, but not very drongly. 
On turning the plain fide towards the balls, it 
caufed them to accede to it, but rather at a greater di- 
dance in this cafe, than they receded from it in the 
lad. When the flow was colder, thefe appearances 
were confiderably dronger ; but, on cooling dill 
more, they were lefs and lefs. 
Exp. 2. I repeated this lad experiment, with the 
difference only of having the balls electrified minus 
indead of plus *. And in this cafe (as might be ex- 
pected) the effeCts were reverfed; the balls acceding 
towards the convex fide, and receding from the plain 
fide. 
Thefe appearances in the two experiments agree- 
ing with one another, diffidently prove, that when the 
flone has been heated by water , one fide is eledlrified 
minus, and the other fide is ele ft rifled plus ; which is 
the fird lav/ laid down by JEpinus. This date has 
not improperly been called its natural [late j becaufe 
the beat , which difpofed the Tourmalin to adord thefe 
appearances, was uniform in every part of its furface, 
and the water itfelf an uniform conductor. 
Exp. 3. I prefented the convex fide to the flame of 
a candle, but not fo near as to touch the flame, and 
held it there about one minute, during which time 
the done acquired a plus electricity on both tides, for 
* I did the fame thing in every experiment where there was oc- 
cafton to ufe thefe balls, to be more certain of the conclufions. 
the 
