ON ELECTRICAL CHARGES AND DISCHARGES. 



«S5 



coatings will give signs of an electricity of the same kind as 

 that of the interior face corresponding to each plate. 



The phenomena exhibited by a compact, charged, inati- Oneof theim- 

 lating plate, one of the uncoated faces of which is brought ^u electrified" 

 into contact with a conducting body, depend on the same "onconducior 

 principles ; but they would also require a minute detail to be contact with a 

 treated fully. To this class of phenomena belong the well conductor. 

 known effects of Volta's electrophorus: and the same gen- The electro- 

 tleman has fi-eed them to a certain degree from the compli- ^ ^"|,^!' 

 cation respecting the charge of the insulating body, in his 

 semiconducting plate doubler, the effect of which appears to 

 me, to belong essentially to the phenomenon of quiescent 

 and revivified electricity, exhibited between a perfectly con- 

 ducting substance, and a substance of sufficient conducting 

 power to exhibit this phenomenon in its simplicity, as inca- 

 pable of being charged, and yet so bad a conductor as to af- 

 ford a charge; while, as we have seen, it cannot take place 

 between two perfectly conducting bodies. But I cannot 

 here enter into the particulars, on which the theory of these 

 two instruments depend. I shall only say, that what Volta 

 himself, and since Haiiy, have said of it, appears to me es- 

 sentially to require the principles in question; but as thi# 

 theory could not be completely developed by these gentle- 

 men, because they had no farther object than to explain the 

 effects of these instruments, they have not generalized it 

 sufficiently. In the course of this paper however, I. shall 

 have occasion to touch on some points relating to this sub- 

 ject. 



Sect. IV. Let us now return to the point in question, Clnr<;etl noM- 

 and apply what has been said of the particular case of the conductor. 

 two plates, at which we had stopped, to the inquiry we had 

 in view respecting the state of a charged insulating stra- 

 tum, ©r that interposed between the opposite electricities. 



For this we want only one more fact,which is equally well es- Two plates 



tablished. It is that if, after having charged the pair of plates ^'^''g^f^^ ""' 



joined together by their uncoated faces, as if they were a charged ,is a 



single one, thev be discharged in the usual way, and we after- f'/'S'^ p"^< ^^• 

 ^, ' ^ *' , 1 . i_ , hibit the same 



■ward endeavour to separate the two plates, we observe the appearances, 



phenomena of the revivification of the electricities, similar to as whencharg- 



those obta,ined from two plates charged separately, afterward *' ^^^'^'^* *■' ^ • 



joined 



