J 54 EleBrlcify and Galvanlfm, 



it nmft be allowed to contribute fomethlng to the effetSl, does 

 not exclude the cooperation of fome other property which 

 may refide in the ammoniac. This opinion i'eemed to the 

 authors to receive fupport from a fubfequent experiment, in 

 which a faturaled folution of potafli exhibited a decided fu- 

 periority over water when both were fuccenively ufed in the 

 fame pile, although it did not at all tarnilh the metals. 



'.Still further to elucidate this point, the authors proceeded 

 to examine the comparative aftion of a pile in vacuo m oxy- 

 gen and in other gaies. 



Having placed 60 pairs of zinc and filver, with a proper 

 metallic communication, under the receiver of an air-pump, 

 and exhauftcd the latter to a preffiire of five lines, they found 

 the aftion of the pile in no way changed. Air was admitted, 

 and again exhaulled, and the pile left in vacuo for an hour, 

 the efteft ftill continuing the fame. Carbonated hydrogen 

 was now admitted into the receiver, and, being afterwards 

 exhaurted, was replaced by azote, without any perceptible 

 variation, in either cafe, from the ufual appearances. Laftly, 

 having again exhaufted the receiver, it was filled with oxygen 

 gas from manganefe. The fliocks now became ftronger, and 

 the fparks much larger, brighter, and eafier to obtain. On 

 exhaufting the oxygen they were furprifed to find the pile 

 now really afiefted by the vacuum, and afting with much 

 lefs force than in either of the preceding cafes. The atmo- 

 fphere of oxygen, and the vacuum after it, being once mord 

 repeated, left no doubt as to the reality of this increafe and 

 diminution of eft'eft; the pile alfo returning nearly to its or- 

 dinary ftrength on being reftored to the atmofpheric air. 



The letter concludes with ftating the effeA of increafing 

 the 5-inch fquare pile to 200 pairs; the difcharge of which 

 melted 23 inches of wire, and entirely reddened 33 inches: 

 alfo three other experiments, which prove that, in order to 

 augment the power of Volta's pile, it is neeelTary to increafe 

 the numberjbut not the furface, of the plates it is compofed of. 



of tlie cffeft of ammoniac, p.operly fpeaking. -It is not extrao'diuHry that 

 fuch iliverfity IhoukI be found among liijiiids as among folids iu their 

 poweis of couduiiMig cltdtriciiy. — H. 



XXX. Cofy 



