electric Charge and D if charge. 1 23 
thrown in, which lie could not do if an equal quantity had 
already gone from the outfide of the jar *. 
When the quantity already fpoken of has been taken from 
the outfide of the jar (the equilibrium being nearly reftored) 
another quantity like the firft may again be added to the inner 
furface : after which a fimilar quantity may again be taken 
from the outfide : thus, by the fucceffion of a fufficient num- 
ber of the quantities allowed by the before-mentioned law, the 
jar may, at length, be completely charged. 
There are other ways of charging coated glafs ; but if it be 
allowed, that the charge, in the foregoing inftance, is produced 
in the manner I have fuppofed, it will not, I think, be dif- 
puted, that all other charges are produced by a fimilar alterna- 
tion of fmall quantities. This, however, will appear more 
clear from the obfervations I (hall now make on the manner in 
which the difcharge is produced. 
When the aftonifhing velocity with which the charge of a 
jar or battery moves through a confiderable fpace is conlidered, 
it may at firft appear impofiible, that the difcharge fhould be 
made by the alternate giving and receiving fuch fmall quantities 
as thofe by which the charge was produced ; yet a more ample 
confideration of the matter will, I think, fhew that it cannot 
1 
poffibly be brought about any other way. 
I prefume it will be granted, that the charge of a jar (in 
difcharging) either leaves it all at once, or goes out by the fame 
fmall quantities by which it went in. To fuppofe any inter- 
* Much difpute has arifen among electricians refpedting the degree of charge 
which may be given to an infulated jar ; but no one, that I know of, has taken 
notice of a deception which will happen, if care be not taken that the fame fide, 
by which the jar is attempted to be charged, be firft touched in trying whether it be 
charged or not; whereas it is clear, from what has been faid, that, if the con- 
trary furface be firft touched, a lmall charge will, from that very circumftance, 
be produced. 
R 2 mediate 
