123 ANALYSIS OF THft GALVANIC PILE, 



discovered by connecting with a condenser the three pointj 

 «, r, b, in fig. 1. I tried a condenser, the plates of which 

 were separated by a piece of silk; butsin these very delicate 

 experiments, it produced deception ; the silk retaining some 

 electrisation from one experiment to the other, 1 was there- 

 Condenser of fore obliged to use a condenser acting by the mere distance 



awpfan. °" a °^ ^ ie l^ ates > anc * * constructed one on a new plan, which 

 answers many purposes. The under, or receiving plate is 

 horizontally fixed on an insulating pillar. By means of a 

 brass wire with an insulating handle, I connect successively, 

 each time during 20 seconds, the above three points with 

 the under plate of the condenser, with which is connected 

 a gold-leaf electroscope. During the time only that the 

 tipper plate is concentrically situate over the former, it is in 

 connection with the ground ; after which, by a proper me- 

 chanism, this upper plate is made to retire, by revolving 

 on an insulating axis, and I observe the divergence then 

 produced in the electroscope. 



Indications of I must still mention another circumstance concerning this 



the electro- class of experiments. When the extremities of the insu- 

 ■scope differs , , ., , , . , , • , , 



according to lated pile are only connected with their electroscopes, the 



circumstances, indications of the latter differ according to external circum- 





o 



stances, which I shall not introduce here, saying only, that 

 sometimes there are indications on both sides, positive at A 

 and negative at B, at various correspondent degrees; some- 

 times also there is only an indication at A, then positive; 

 and at other times, as in the above case, the divergence is 

 only at B, and negative. But if A be placed in communi- 

 cation with the ground, the whole electric difference be- 

 tween the extremities is expressed at B with the negative. 

 sign; and on the contrary, if B communicates with the 

 ground, the whole difference is expressed at A with the po- 

 sitive sign. I must also remark here, that there are two 

 different standards, very distinctly and judiciously defined 

 in Sig. Volta's system, to which these comparative expres- 

 Twi» different sions refer. The two standards frequently agree, but often 

 standards. ;i ] so t j )e y differ, from a cause which I shall explain on' ano* 

 ther occasion. When the divergence of balls or gold leaves 

 in the electroscopes is considered alone, the standard of 

 plus and minus is only the actual electric stale of, the ambient 



air; 



