the Galvanic Cuneni through Chareeal, 327 



elapfed, before any gas was produced from the zinc fide ; the gas that was produced ad- 

 hered to the charcoal in large globules, and did not pafs through the water. As long as 

 the communication was kept up, the filver charcoal gave out gas very rapidly. 



2. Reafoning from the common phenomena of the a£lion of red-hot charcoal on water, 

 and on the analogous galvanic fafts, it was rcafonable to conclude that the gas evolved 

 from the charcoal on the filver fide of the apparatus was hydrocarbonate ; and that car- 

 bonic acid had been produced on the zinc fide, which had been chiefly abforbed by 

 the water. 



To afcertain if this conclufion was true, two fmall open tubes, about one-fourth of an 

 inch in diameter, and three inches long, were provided. Into one end of each of them a thin 

 piece of hard and polifhed charcoal was introduced, and faftened by cement. They were 

 then filled with diftilled water, and inverted in a glafs containing that fluid ; the tops of 

 the pieces of charcoal being made to communicate with the ends of a pile. 



The procefs was carried on for more than fourteen hours ; at the end of which time 

 the quantity of gas produced from the charcoal on the filver fide was at leaft fifty times 

 greater than that produced on the zinc fide. The tube from the zinc fide, with its water 

 and gas, was introduced into a vefl'el of lime water. On agitation the water became 

 clouded, but the gas was not perceptibly diminiflied : mingled with twice its bulk of 

 nitrous gas, it gave fuch an abforption, as denoted that it contained nearly the fame quan- 

 tity of oxygen as common air. 



The gas produced from the filver fide of the pile did not at all diminifli with nitrous 

 gas ', twelve meafures of it, mingled with eight meafures of oxygen, in a detonating tube, 

 and a£ted on by the eledric fpark, inflamed and left a refiduum equal to rather more than 

 three meafures. Lime water introduced to thefe became a little clouded, and a flight 

 abforption took place. After this abforption, at leaft two meafures and a quarter of gas 

 remained, which, mingled with nitrous gas, gave red fumes and diminution. Hence 

 they evidently contained oxygen. 



3. Surprifed at thefe refults, from which it appeared that the gas from the filver fide 

 of the apparatus held very little charcoal in folution, and required nearly the fame quantity 

 of oxygen to deftroy it as the inflammable air from the metals, I repeated the experiment, 

 making ufe of water that had been long boiled, and was yet warm. In this cafe no gas 

 was given out from the zinc fide during the whole of the procefs, and more than half an 

 hour elapfed before any was produced from the filver fide. What was produced, however, 

 gave nearly the fame diminution, when fired with oxygen, as common inflammable ^ir, 

 and the refiduum produced but a flight precipitate admitted to lime water. 



It was eafy to account for the deficiency of gas on the zinc fide in this procefs, by fup- 

 pofing that the gas produced in the former experiment was air previoufly diflfolved by the 

 diftilled water, and liberated in confequence of the ftronger attra£l;ion of carbonic acid 

 for that fluid ; but as I had before found that in the common galvanic procefs with the 

 metals, the hydrogen was immediately evolved, even in boiled water, it was difficult to 



concei\Ee 



