ON ELECTRICAL CHARGES AND DiSCHAnOES. <Jgg| 



phials, panes of glass, &c., have so much the greater capa* 

 city for a charge, otlier circvinistances being equal, in pro- 

 portion as their thickness is less. 



This admitted, let us suppose, that the surfaces of cur Caseef twja 

 two ribands, endued with opposite electricities, are gradu- P^^^l"^^^^^* 

 ally brought nearer to each othc*, keeping them parallel. 

 The repulsive force of each of these two electricities will 

 render itself so much the more perceptible, and they will 

 have so much the less tendency to be conveyed away by the 

 surrounding bodies, as their distance is diminished ; because 

 the attraction between the two electricities will become so 

 much the greater: and when at length the surfaces are 

 brought into contact, th^ attraction having become as it 

 were infinite, these electricities will no longer tend to fly 

 off, but will remain as if they did not exist with respect to 

 other bodies, whatever intensity they had before, since this 

 intensity was limited, and the repulsion ai'ising from it was 

 also limited. 



Thi^ may be exhibited in another point of view. When Charged pliOa 

 we charge a plate of glass, the electricity produced on the °^g^*s*- 

 interior face of the coating opposite that which is electrified 

 directly has no tendency to fly off, because it is perfectly re- 

 tained by the attraction of the electricity of the latter coat- 

 ing; an electricity which, according to the principles of 

 Coulomb and Haiiy, to produce this effect must be con- 

 ceived somewhat greater, than that which is produced on 

 the opposite face gf the plate, The electricity of the face 

 electrified dii-ectly is on the other hand perfectly retained by 

 that of the opposite face, with respect to the portion equal 

 to it : and it is only its excess that has a tendency to be dis- 

 sipated, and requires the resistance of the air to retain it. 

 Now Hai'iy has already observed, that this excess, according 

 to the theory, must be so much the less, in proportion to the 

 thinness of the plate; and that it would be nothing, if the 

 plate were infinitely thin, or in other words nought. Nei- 

 ther of the two electricities then, that compose the charge, 

 would any longer tend to fly off; they woxild become insen- 

 sible, This is precisely the case of the electricities of our 

 pvo ribands, considered as coatings of the stratum of air at 



first 



