200 



ON THE PILE OF VOLTA, 



Cold; 



Charcoal not 

 diffolved, &c. 



Iron; sine} 

 copper. 



In four vcffels of 

 water, with wires 

 forming the cir- 

 «uit, the pheno- 



diflblved. Iron and zinc were the means of" diflblving eacli 

 other. But the fureft method of producing this folution ©f 

 metal was by connecting charcoal with the filver end of the 

 pile. I once diflblved pure gold in this manner, and I pre- 

 fer ve the folution as an evidence of it ; but I could never do 

 it a fecond time, though I tried charcoal in feveral ftates, 

 perfect and imperfect, &c. nor could I by this procefs dilTolve 

 platina. 



Charcoal itfelf is not fenfibly diffolved in this procefs, and 

 air comes from the pieces connected with both ends of the 

 pile. Sufpecling that this air might be that which always 

 comes from charcoal when it is plunged in water, I rilled the 

 pores of two pieces of it with water, by means of the air 

 pump, leaving them a long time in vacuo. Being then tried > 

 they gave no air of fome hours, but from the piece that was 

 connected with the zinc end of the pile there proceeded a 

 white cloud, which filled part of the veffel of water. This, 

 however, foon difappeared, the water becoming tranfparent 

 again ; and after fome hours both the pieces of charcoal gave 

 air as copioufly as any of the metals had done, and continued 

 to do fo as long. 



When iron was connected with the filver end of the pile, 

 and copper with the zinc end, the latter was diffolved, but 

 not till after two or three hours. Zinc being connected with 

 the filver end, and copper with the zinc end, the former gave 

 air copioufly from the beginning, but it was near two hours 

 before the copper began to diflblve, which (being a flat piece) 

 it did at the corners and edges only, and never from any part 

 of the flat furface. When I added more copper, it began to 

 give air without diflblving, and alfo fome of the green preci- 

 pitate, which had been formed before, gave out air, and, the 

 bubbles adhering to it, it rofe from the bottom of the veffel to 

 the top. This precipitate from the copper* which at firfl was 

 green, became afterwards of a dark brown, as if the metal 

 had been revived. This too was the cafe with one veffel in 

 which a folution of filver had continued fome time. It has 

 given a coating to the glafs that is perfectly white and bril- 

 liant. 



Having introduced four veffels of water between the two 

 ends of the pile, and having connected each two with filver 

 wires, that leg of the wire, in all the ve/Tels, which was next 



to 



