C 3*7 3 
pith of older, and fufpended by two linnen threads 
of the fined: kind : the ends of thefe threads I fatten 
to a flip of wood about three inches long, and half an 
inch broad : then upon a ttick of dealing wax nine 
inches long, fixed upright on a table, or any other 
convenient place, I fatten the flip of wood, from one 
end of which the threads &c. hang down five inches, 
fo that the pith balls are about four inches from the 
table. Thefe balls are always fuppofed to be electri- 
fied plus, except where the contrary is mentioned : but 
with no greater power, than to make them recede 
from each other about one inch in every experiment. 
I prefer the wax ftand to a glafs one, as the latter 
when cold acquires moifture very foon, and therefore 
becomes a conductor: whereas wax, when it is once 
in good order, will continue a non-conduCtor for a 
long time. 
Before I fet down my experiments, I mutt mention 
three truths that are commonly known, and which, 
for the prefent, I fhall call 
General Laws. 
Two bodies equally electrified plus recede from 
each other, or are repelled. 
Two bodies electrified minus recede alfo from each 
other, or are repelled. 
One body electrified plus and another body electri- 
fied minus , to an equal degree, accede, or move to- 
wards each other, or, as it is generally exprefled, are 
attracted. 
Experiments upon the Tourmalin. 
Exp. i. One edge of the Tourmalin being properly 
fattened to a long ttick of fealing wax, I dipped the 
8 ttone 
