ON THE PILE OF VOLTA. . 201 . 



to. the filver end of the pile gave inflammable air, while, in rrcena ceafed, 

 all of them, the other leg of the fame wire was diflblvcd. j£« ^ ^ 

 When I covered one of thefe veflels with oil, the production vered with oil. 

 of air and the folution of the wires ceafed in them all." 



Though, as I have obferved, there was a flight appearance No arid found 

 of acidity in the water when dephlogifticatcd air was given ^fly^ 

 out at the wire communicating with the zinc end of the pile, 

 there never was the fmalleft appearance of it when the metal 

 was diflblved. When filver was diflblved in water tinged 

 with the juice of litmus, and there was a copious production 

 of inflammable air from the oppoflte wire, I could not per- 

 ceive the leaft change of colour in the water. 



I examined the water in which the procefs was made, efpe- The air in the 

 cially when filver was diflblved in it, but was fo far from than common 

 finding the air contained in it more pure than before, that it air. 

 was evidently Iefs fo. Before the procefs, the ftandard of this 

 air, with an equal quantity of nitrous air, was 1.1 ; with the 

 water made turbid and white with the folution of filver, it was 

 1.2 ; and after ftanding till it became black, it was 1.3. 



The black matter from this folution of filver did not contain The black pow- 

 any oxigen, but was evidently the metal fuperfaturated with t ^ r n ° hidrogen " 

 phlogifton ; for wdien it was heated in dephlogifticatcd air, &c. 

 it diminiflied it, and converted part of it into phlogifticated 

 air ; and when it w r as heated in inflammable air, it added to 

 the quantity of it, and this appeared, by its explofion with 

 dephlogifticated air, to be as pure as other inflammable air ; 

 fo that this black powder of filver is fimilar to the black pow- 

 der of mercury made by agitation in water, which I have 

 fhewn to be mercury fuperfaturated with phlogifton. Where, 

 then, is the oxigen that ought to be produced in great quantity, 

 if the inflammable air from the wire connected with the filver 

 end of the pile came from the decompofition of the water? 



The glafs veflels in which filver has been diflblved in thefe The glafs veflels 

 proportions are tinged of a dark colour, which no acid, nor ar « Slackened, as 

 any other inenftrnuin that I have applied, will take out. This 

 is fimilar to the cafe of ijint glafs becoming black by heating 

 inflammable air in it, the calx of lead in the glafs uniting with 

 the phlogifton of the air. In this cafe, therefore, it is natural 

 to infer that this calx of filver imparts phlogifton to the glafs, 

 and that there was nothing of oxigen in it. The furface of 

 djis black powder of filver Igrg expofed to the air while it is 



moifl 



