BENJAMIN FRANKLIN. 41 



are the interior and exterior coatings, which, before the pro- 

 cess of charging has commenced, are of course in their 

 natural state, each having exactly that quantity of electricity 

 which its matter is able to balance, and neither therefore 

 exerting any effect whatever upon the other. But no sooner 

 has the interior coating received an additional portion of 

 electricity from the prime conductor, with which the reader 

 will remember it is in communication, than, being now 

 positively electrified, it repels a corresponding portion of its 

 electricity from the exterior coating, which therefore becomes 

 negatively electrified. As the operation goes on, both these 

 effects increase, till at last the superabundance of electricity 

 in the one surface, and its deficiency in the other, reach 

 the hmit to which it is wished to carry them. All this 

 while, it will be remarked, the former is prevented from 

 giving out its superfluity to the latter by the interposition 

 of the glass, which is a non-conductor, and the uncovered 

 space which had been left on both sides around the lip of 

 the vessel. If the charge were made too high, however, 

 even these obstacles would be overcome, and the unbalanced 

 electricity of the interior coating, finding no easier vent, would 

 at last rush through the glass to the unsaturated matter on 

 its opposite surface, probably shattering it to pieces in its 

 progress. But, to effect a discharge in the usual manner, 

 a communication must be established by means of a good 

 conductor between the two surfaces, before this extreme 

 limit be reached. If either a rod of metal, for example, or 

 the human body, be employed for this purpose, the fluid 

 from the interior coating will instantly rush along the road 

 made for it, occasioning a pretty loud report, and, in the 

 latter case, a severe shock, by the rapidity of its passage. 



