^4* Account offoine Calvaiilc Combiiintloiis, 



It appeared, in feveral experiments, that feries of double metallic plates, incapable of 

 aftlng as Galvanic combinations, when arranged in the proper order, with portions of 

 water, were readily made to produce Galvanic effefts, by being alternated with acids, or 

 other fluids capable of oxidating one only of the metals of the feries. Thus, double plates, 

 compofed of filver and gold, (metals which have been fuppofed to differ very little in their 

 powers of conducing eledlrity,) produced Galvanic aftion, when placed in contaiSt, in the 

 common order, with cloths moiftened in diluted nitric acid. And copper and filver a£ted 

 powerfully with nitrate of mercury. 



Thefe facSs induced me to fuppofe, that the alternation of two metallic bodies with 

 fluids, was effential to the produdlion of accumulated Galvanic influence, only fo far as if 

 furnilhed two condufling furfaces of different degrees of oxidability ; and that this pro- 

 duction would take place, if fingle metallic plates could be conne£led together by different 

 fluids, in fuch a manner that one of their furfaces only fliould undergo oxidation, the ar- 

 rangement being regular. 



On this fuppofition, I made a number of experiments on different arrangements of fingle 

 metals and fluids; and, after many various proceffes, I was enabled to afcertain, that many 

 of thefe arrangements could be made aftive, not only when oxidations, but likewifc when 

 other chemical changes were going on in fome of their parts. 



In defcribing the different Galvanic combinations formed by fingle metallic plates and 

 fluids, I (hall divide them into three claffes, following, in the arrangement, the order of 

 time with regard to difcovery. 



II. The firft and mod feeble clafs is compofed, whenever fingle metallic plates, or arcs, 

 are arranged in fuch a manner that two of their furfaces, or ends oppofite to each other, 

 are in contaft with different fluids, one capable, and the other incapable, of oxidating the 

 metal. In this cafe, if the feries are numerous, and in regular alternation. Galvanic in- 

 fluence will be accumulated, analogous, in all its effects, to the influence of the common 

 pile. 



Tin, zinc, and fome other cafily oxidable metals, acl moft powerfully in this clafs of 

 combinations. 



If pieces of polifhed tin, about an inch fquare, and ^"5 of an inch thick, be conne£led 

 with woollen cloths of the fame fize, (moiftened, fome in water, and fome in diluted ni- 

 trous acid,) in the following order, tin, acid, water, and fo on, till twenty feries are put 

 together, a feeble Galvanic battery will be formed, capable of acting weakly on the organs 

 of fenfe, and of flowly producing the common appearances in water ; the wire from the 

 oxidating furface of the plates evolving hidrogen ; and the wire from the non-oxidating 

 furface (when of filver) depofiting oxide. 



In 'ill cafes, when the batteries of the firft clafs are erefted perpendicularly, the cloth 

 moiftened in acid muft be placed under the cloth moiftened in water ; and, in this arrange- 

 ment, as the acid is fpecifically heavier than water, little or no mixture of the fluids will 

 take place. 



When 



