398 Mr. Davy’s Account of Galvanic Combinations , 
acids, or other fluids capable of oxidating one only of the metals 
of the series. Thus, double plates, composed of silver and gold, 
(metals which have been supposed to differ very little in their 
powers of conducting electricity,) produced Galvanic action, 
when placed in contact, in the common order, with cloths 
moistened in diluted nitric acid. And copper and silver acted 
powerfully with nitrate of mercury. 
These facts induced me to suppose, that the alternation of 
two metallic bodies with fluids, was essential to the production 
of accumulated Galvanic influence, only so far as it furnished 
two conducting surfaces of different degrees of oxidability ; and 
that this production would take place, if single metallic plates 
could be connected together by different fluids, in such a man- 
ner that one of their surfaces only should undergo oxidation, 
the arrangement being regular. 
On this supposition, I made a number of experiments on dif- 
ferent arrangements of single metals and fluids ; and, after many 
various processes, I was enabled to ascertain, that many of these 
arrangements could be made active, not only when oxidations, 
but likewise when other chemical changes were going on in 
some of their parts. 
In describing the different Galvanic combinations formed by 
single metallic plates and fluids, I shall divide them into three 
classes, following, in the arrangement, the order of time with 
regard to discovery. 
II. The first and most feeble class is composed, whenever 
single metallic plates, or arcs, are arranged in such a manner 
that two of their surfaces, or ends opposite to each other, are in 
contact with different fluids, one capable, and the other inca- 
pable, of oxidating the metal. In this case, if the series are 
