[ 3 68 ] 
Upon admitting a very fmall quantity of air into the 
tube, thefe phenomena difappeared ; not fo much from 
the fmall quantity of air admitted, as from the vapours, 
which infinuated themfelves therewith. Thefe lined the 
frdes of the glafs, and conduced the electricity imper- 
ceptibly from one end of the tube to the other. And 
to illuflrate farther, that the vapours, and not the air, 
in the fmall quantity admitted, occalion’d this total 
difappearing of thefe phenomena ; upon experiment 
they have been vifible, though in a lefs perfedt de- 
gree, when a much larger quantity of air was omit- 
ted to be exhauffed from the tube. 
Thefe experiments feem to evince, that however 
great the vacuum could be made, the electrical co- 
rufcations would pervade it through its whole length. 
From hence it appears, that our atmofphere, when 
dry, is the agent, by which we are enabled to accu- 
mulate electricity upon non-eledtrics ; as in the expe- 
riment before us, upon the removal of it, the elec- 
tricity palled off into the door through a vacuum , 
of the greatelt lengrh we have hitherto been able 
to make, became vifible in this vacuum , and ma- 
tt ifefted itfelf by its effeCts upon the air-pump, 
being the non-eledtric fubftance, which terminated 
that vacuum : whereas, when the air is not taken 
away, the diflipation of the electricity is from every 
part of the prime conductor. We fee here alfo, con- 
trary to what we have found hitherto, that an ori- 
ginally-electric body, viz. a dry glafs tube, puts 
on the appearance of a non-electric, by becoming 
itfelf the conductor of electricity, that is, by its keep- 
ing out the air, and fuffering the electricity to per- 
vade the vacuum . 
Flow 
