[ 321 3 
have flowed y.^n it towards the iron. That this was 
really the fa£t will appear prefently. 
Exp. 8. When I heated the convex lide in the 
fame manner as I did the plain one, the balls were 
not moved towards the 1 Tourmalin , but from it, and 
continued in that date. In this experiment they were 
electrified plus, and the done alfo was plus on both 
lides. 
I gathered from this experiment that the plus elec- 
tricity in the done did not flow from the balls, be- 
caufe they lod none of their virtue but it mud be 
from the iron it } elf. 
It was now neceflary to examine the iron : but I 
found it very difficult to do this for many reafons, 
and fuch as might perhaps be thought too tedious if 
I mentioned them. 
I therefore had recourfe to another expedient, 
where there was a probability of meeting with better 
fuccefs. This was to make ufe of a tube of glafs 
about two feet long, one end of which I heated red 
hot and tried the experiments again: obferving at the 
fame time the date of the glafs after each experi- 
ment. 
Exp. p. When the plain fide of the 'Tourmalin was 
expofed to the heated end of the glafs, in like man- 
ner as it was to the knob of iron in the feventh ex- 
periment, I obferved that about three inches of the 
heated part of the glafs was eleSlrified minus , and be- 
yond that didance it was electrified plus , and conti- 
nued fo even when the glafs was very near cold. 
This plus and minus date in the glafs, mud be 
caufed from the aCtion of the fluid flowing from the 
V ol. LI. T t balls 
