304 lirpori to the French National Injlitufe 



vhich that liquid, as an imperfeft condii6lor of eleftricltv, 

 can oppofe to tlie communication. The apparatus being in- 

 fulated, the excels of the upper part can be acquired only at 

 the expenfe of the piece of copper which is below : the re- 

 fpeftive dates of thefe pieces will be 110 longer the fame as in 

 the preceding experiment, and will become. 



In the lower piece, which is of copper, — tj '^ ^^^ ^^" 

 cond, which touches it, and which is of zinc, — y + x, or y- 



The third, which is of copper, and which is feparated from 

 the preceding bv a piece of moill card, will have the fame 

 quantity of eleftricity, that is to fay, + 1 ; and the fum of 

 the quantities of electricity Ibft bv the firft piece and acquired 

 by the other two^ will be ilill equal to zero, as in the cafe 

 or the two pieces. 



If we add a fourth piece, which will be of zinc, it muft 

 have ail unit more than that of the copper over which it is 

 immediately placed : as this excefs can be acquired only at 

 the expenfe of tlir inferior pieces, fincc the pile is infulated, 

 we fliall have : 



For the lower piece, which i? of copper, — i : for the fe- 

 cond piece, which touches it, and which is of zinc, 05 that 

 is to fay, it will be in its natural Italc; 



For the third piece, which is of copper, and which is fe- 

 parated from the former by a piece of moid card, oj it will 

 be alio in its natural Itate ; 



Laftlv, for the upper piece, which is of zinc, and which 

 is in contaft with the preceding, — • i. 



Purfuin<i the lame realbning, the eleftric ftate of each 

 piece of the pile will be found bv fuppofing it infulated, and 

 formed of anv number of elements ; the quantities of clec- 

 trieiiv will increale for each of them, from the bafe to the 

 fumniil of the column, according to an arithmetical progref- 

 lion, the fum of which will be equal to zero. 



For the orcater fimplicity, if we fuppofe that the number 

 cf the elements is even,' it will be eafy to afcertain, by a very 

 iimple calculation, 



That the lower piece which is of copper, and tlie upper 

 piece which is of zinc, mull be equally elei^^rified, one more 

 and the other lefs ; and the cafe will be the fame in regard to 

 the pieces taken at an equal diftance from the extremities of 

 the pile. 



The eleftricitv, before it pafles from pofitive to negative, 

 will become null ; and there will ahvavs be two pieces, one 

 of zinc and the other of cop.per, whicli will be m the natural 

 Itate. They will be in the middle of the pile: this is what 

 has been iecn in the cafe of four pieces, for example. 



6 Let 



