HISTORY OF GALVANISM. 7 



water, the filver end emitted from the water a brum of fire, at Jercnt kinds of 

 the fame time that the zinc end produced only a denfe fpark» 

 Thiscircumftance induced him tofuppofe that the filver was in 

 the plus and the zinc in the minus ftate of electricity, which in- 

 deed agrees with Bennetts original experiments, though it dif- 

 fers from the account given by Mr. Nicholfon in his firft paper, 

 and alfo from the experiments of Dr. Wollafton, Dr. Van 

 Marum, and others, as we (hall lee below. 



Dr. Wollafton read a judicious paper to the Royal Society, Dr. Worafton. 

 which appeared in the Tranfadions for the year 1801. He Oxidation difen- 



rr J gages electneity> 



remarks, as Mr. Davy had previoufly done, that the energy ot 



the pile feems proportionate to thedifpofition which one of the 



plates has to be oxidated or acted upon by the interpofed fluid. 



If a piece of filver and a piece of zinc be immerfed in diluted 



fulphuric acid, the zinc immediately begins to decompofe the 



water and to evolve hidrogen ; the filver is not acted upon, 



but if we bring them into contact, the filver alfo begins to pro-, 



duce hidrogen. He therefore concludes, that in the folution 



of a metal by an acid, electricity is always difengaged. In from the amal- 



order that the eledrical machine mould act ftrongly, it is ne- gam , of theel * 



° J machine j 



ceflary that the amalgam upon the cumion mould be compofed 

 of a metal which is eafily oxidated ; the Doctor alfo found that which will not 

 an electrical machine plunged into carbonic acid gas is incapable ^-J* Car ° n ' C 

 of being excited. He concludes by the opinion which was fug- 

 gefted by Mr. Nicholfon, that electricity andgalvanifm are the 

 fame principle, but that in the latter it is generally met with 

 in large quantity, but in a ftate of low intenlity. Dr. Wollafton He firft pro- 

 coated two filver wires, leaving the ends only of them expofed /""IS f alva * 

 thefe wires were connected with the two conductors of an elec- water by com- 

 trical machine, and the fpark was taken from one to the other mon electricity, 

 through a folution of copper : he found that the end of the wire 

 connected with the negative conductor was covered with re- 

 duced copper; no change had taken place in the other end. 

 The negative conductor appears therefore, from thefe experi- 

 ments, to correfpond with the filver end of the pile. 



Mr. Davy's very curious difcovery, that a galvanic pile Mr. Davy's pile 

 might be conftructed by one metal alone, provided its different witn °nc fingle 

 furfaces were expofed to the action of different fluids, has been a * 

 already announced: In addition to thefe facts the fame intelli- 

 gent experimenter informs us, in the firft vol. of Nichpifon's 

 Journal, N. S. that he has conftructed a galvanic apparatus 



which 



