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of A , bring the excited glafs tube ; and holding it a 
fhort time, at the diftance of a few inches, each pair 
of balls will be obferved to feparate : withdraw the 
tube, and the balls of A will come together, and 
then repel each other again ; but thofe of B will 
hardly be affected. By the approach of the excited 
glafs tube, held under the balls of A, their repulfion 
will be increafed : but if the tube be brought, in the 
fame manner, towards the balls of B , their repulfion 
will be diminished. 
In the fifth experiment, the common flock of 
electrical matter in the tin tube, is fuppofed to be 
attenuated about the middle, and to be condenfed at 
the ends, by the repelling power of the atmofphere 
of the excited glafs tube, when held near it. And 
perhaps the tin tube may lofe fome of its natural 
quantity of the electrical fluid, before it receives any 
from the glafs 5 as that fluid will more readily run 
off from the ends or edges of it, than enter at the 
middle : and accordingly, when the glafs tube is with- 
drawn, and the fluid is again equally diffufed through 
the apparatus, it is found to be electrified negatively: 
For excited glafs brought under the balls will increafe 
their repulfion. 
In the fixth experiment, part of the fluid driven 
out of one tin tube enters the other ; which is found 
to be electrified pofitively, by the decreafing of the re- 
pulfion of its balls, at the approach of excited glafs. 
Experinicnt 7. 
Let the tin tube, with a pair of balls at one end, 
be placed three feet at lead from any part of the 
room, and the air render’d very dry by means of a 
fire : 
