on the Experiments of Volta. 305 



Let ns now fuppofe that the communication is eftabliflied 

 betuetn the lower part of the pile and the common refervoir: 

 it is evident that in this cafe the lower piece of copper, which 

 is neaativelv ek-6lrified, will tend to refume from the ground 

 whatsit has loft; but its electric ftate cannot be changed 

 without that of the upper pieces varying, fince the elettric 

 difference of the one from the other muft always be the fame 

 in the Itate of equilibrium. It is neceflary, then, that all the 

 negative quantities of the lower half of the pile (hould be 

 neutralized at the expenfe of the common refervoir; and then 

 it will refull : 



That the lower piece, which is of copper, will have the 

 fame degree of eleilricity as the ground, which fliall be re - 

 prefented by o ; 



The fecond piece, which is of zinc, and which immedi- 

 alelv touches the preceding,will have + i ; 



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

 the lower one of zinc by a piece of moid pafteboard, will 

 have, like it, + i ; 



The fourth, which is of zinc, and which touches the pre- 

 ceding, will have + 2 ; 



And the quantities of the eleftricity of the different ele- 

 ments will increaie in this maimer according; to an arithme- 

 ticul progrellion. 



if the fummit of the pile be then touched with one hand, 

 and its bafe with the other, thefe exceffes of eleftricity will 

 be diicharged through the organs into the common refervoir; 

 and will give a fliock the more fenfible, as, this lofs being 

 repaired at the expenfe of the ground, there muft thcn.cc 

 refuU an eleclric current, the rapidity of which, greater iu 

 the interior of the pile than in the organs, which are im- 

 perfect condiitlors, permits the interior part of the pile to 

 refume a decree c)f tenfion approaching that which it had iu 

 the ftate of equilibrium. 



The communication being ftill cftabiiflied with the com- 

 mon refervoir, if tlie fumnnt of the pile be brought into con- 

 \-iS( with the upper plate of a condenfer, the lower one of 

 which touches the ground, the cle6lricity, which at that ex- 

 ircmiiy was in a verv weak degree ofteuiion, will pafs into 

 the condenfer, where the tenfion may he confidercd as nuUj 

 but the pile being infulated only at the expenfe of the com- 

 mon refervoir, the new quantities of cletlricity, recovered 

 by the u[)per plate, will pafs into the condenfer like the pre- 

 ceding, and will be there, at lent.lh, accunuiUited in fuch 

 a manner, that, bv fcparating the cc l;ei!"liiig plate, ^-ery fen- 

 fible elettromeiric fians, and even fparks, may be extracted. 



V01-. xr. " U la 



