64 VoUa on Animal EL'Siricifj', 



are held alfo by thcfe perfoils, and A, A, two pieces of filvcf, 

 which are held by a third perfon, denoted alfo by p. It mull 

 not be forgotten that the hands fhculd be very moitl:, -as the 

 dry Ikin is not a condnclor fufiiciently flrong. As in this 

 chain the a6lions of the electric exciters are oppofed to each 

 other and in exacit equilibrium, as may be readily perceived, 

 no convulfion or agitation in the frog will take place. 



Now, let one of the metallic pieces A, Z, which ftand be- 

 tween the two perfons p, p, or between anyother nioiil: con- 

 dutlors, be left In combination as it is; and let the polition 

 of the two other metallic pieces A, Z, be reverfcd, by convert- 

 ing fig. 13 into fig. 13 (fo that the aftions, inftead of being 

 contrary, will acl together to impel the eleftric fluid to one 

 fide or to produce the fame current) ; or introduce between 

 A and Z anolher perfon, or any other conduftor of the fc- 

 cond clafs, fo that the chain be formed as in fig. 14 ; or take 

 away one of the pieces A, Z, in fig. la, and make the chain 

 like thofe of fig. 15 and 17 ; or, in the lad place, remove the 

 whole two pieces A, Z, either in the one or the other fide, as 

 rcprefcnted fig. 17 (by which means it will correfpond with 

 fig. I, as the whole chain p, g, p, p, may bo confidered as a 

 fingle moill conduftor of the fecond clafs); in all thefe com- 

 binations, which are rcprcfented by fig. 13, 14, i^, 16, and 

 17, the atSlior.s arifing from the metallic contacts are no 

 Ipnger contrary to each other, or in equilibrium, as they were 

 in fig. 13 ; confequcntly an cleftric lircam is produced, and 

 tile frog g, which I fuppofe to be properly prepared, and 

 vihich fonns a part of the chain, will be violently agitated as 

 often as the circle, when broken at any one place, particu- 

 larly between metal and metal, is again reftored. 



In regard to the experiment where a moift condLiftor, or 

 one of the fecond clafs, is to be introduced between the two 

 pieces A, Z (fig. 14), that is, between two different metals, a 

 drop of water, or a fmall bit of moiitened fpcnj^c, or a thin 

 ftratum of any fluid, foap, or any other vifcous matter, will 

 be quite fufficienf, as I have already obferved refpe^ling fig. 9. 



Tins 



