OfJO ANALYSIS OF THE GALVANIC PILE. ■ 



handle, into contact with the condenser. It is commonly 

 supposed, that the latter must be touched while it lies on 

 the other; but this, assimilating; the process to that of the 

 electrophorus, changes the nature of the phenomenon, and 

 may lead into erronr. I shall therefore first relate the ex- 

 periments which I have made, with disks of the two metals 

 about 4 inches diameter, from which the difference between 

 these effects will be seen. But 1 must premise, that in 

 these experiments, the results are very various, at different 

 times, with respect to the quantity of effect ; I shall there- 

 fore relate first such experiments as I set clown in a certain 

 part of one day : then mention the differences. 



Exp. .'30. fix]). 30. I held the copper plate on my hand, and laid 



upon it the zinc plate, which I touched with my finger in 

 this situation, and then carried to the condenser: after 20 

 repetitions or these alternate contacts, the divergence, then 

 positive, of the gold leaves of the latter, was about half an 

 inch. 



gip^Sl, Exp. 31. I made the same experiment without touching 



the sine plate: the gold leaves struck the sides. J repeated 

 the same process with only 10 alternate contacts, and the 

 same quantity of effect was produced as with 20, when 

 touching the zinc plate. 



I must now mention, that at other times I have found 

 no ' difference of effect from either touching or not touching 

 the zinc disk while lying on the copper disk ; and that at 

 different times the quantity of effect in both operations was 

 smaller; a point to which I shall return: but these first 

 experiments prove directly, that when zinc is in communi- 

 cation with copper, the former takes from the latter some 

 electric fluid, making other bodies, on its opposite side, 

 share Its exce&f. Thus, after a certain number of repeti- 

 tions of the alternate contacts, when the npper plate of the 

 condenser is removed, the Jlvid accumulated on the receiv- 

 ing plate is manifested by the electroscope: and instead of 

 having increased the effect by touching the zinc on the cop- 

 per, the finger has sometimes, even during that contact, 

 taken off a part of the accumulated Jinid. 1 come to the 

 reverse experiment, made also at a certain part of one day. 



Exp 98. Exp. 3 J. I took the zinc disk ou my hand, and, placing 



the copper disk on it, I touched the latter before carrying it 



to 



