274 ON GALVANIC PHENOMENA. 



servation on the galvanic pile, related in p. 132 of your 

 Journal for June 1810; for the extremity of this pile actu- 

 ally terminated by silver produced the positive divergence 

 in the gold leaves connected with it ; and the other, actually 

 terminated by zinc, made them diverge as negative', which 

 was the reverse of what Mr. Haiiy had found in his experi- 

 ments. I had discovered the cause of my illusion, as ex- 

 plained in the same paper; but this being an important 

 point in galvanism, and wishing to ascertain it for my own 

 conviction (not in view of Dr. Maycock's experiments, 

 since 1 did not know them), I repeated the original experi- 

 ments with the plates above mentioned. 



Repented con- These experiments showed me first the certainty of the 

 tacts of the « , , . , . , . , . , 



plates neces- fundamental point, that, in their contact, the zinc plate 



saty to produce became positive, and the silver plate negative. But the 

 any sensible «.•-'- L c *i • • .. e 



effect. most important part ot this experiment tor my present pur- 



pose relates to the small effect, which one single operation 

 produces on the gold leaves. Mr. Haiiy having used plates 

 as large as those with which Dr. May cock has made his 

 experiments, ten repetitions of the operation on his condenser 

 were sufficient to produce a sensible divergence of the gold 

 leaves; whereas my plates being only 4 inches in diameter, it 

 required twenty repetitions of the alternate contacts with my 

 condenser, to produce a sensible divergence of very narrow 

 and long gold leaves. But besides, the experiments which 

 follow that in my paper prove also, that a certain number 

 of those contacts produce the same electrical effect, as the 

 same number of groupes of the two metals remaining in con- 

 tact with each other; to which object I shall return here- 

 after. 

 Dr. Maycock The opinion, however, that one single operation with the 

 '"^"fncttl b y two plates was sufficient to produce a sensible electrical effect 

 opinion. seems to have influenced Dr. Maycock's galvunic system; 



for, in continuation of the above quoted part of his theory, 

 he thus continues, p. 26: " The experiments, to which I 

 '* have just alluded, appear to be perfectly sufficient to 

 " point out the fallacy of the explanation, which is very 

 «* generally received, of the excitement of the galvanic pile ; 

 «' the whole of which rests on the assumption, that dissimilar 

 <* metals, while in contact, are in different electrical states, 



the 



