32 REPORT — 1839. 



First fact. 



A piece of iron was voltaically associated with a piece of zinc, and 

 each of these metals put into a separate vessel filled with common water. 

 The vessels did not communicate with each other. Only a few hours 

 after the immersion of the iron had been effected, light flakes of oxide 

 of iron made their appearance round the metal ; and, after a couple of 

 days, the latter was corroded to a considerable degree. The same re- 

 sult was obtained when I plunged the iron piece into water, and made 

 the zinc rise above the level of the fluid, so as to prevent the latter metal 

 from being in the least contact with water. According to the judge- 

 ment of my eye, a piece of iron, being immersed into water without 

 any voltaic association, was no more corroded than that metal appeared 

 to be under the circumstances just stated. 



Second fact. 



Two pieces of iron wire were made, one of them the positive, the 

 other the negative pole of a voltaic pile, which consisted of ten pairs 

 of copper and zinc, and was charged with water holding 5 per cent, of 

 common salt dissolved. Each of the polar wires was put into a sepa- 

 rate vessel filled with common water, so as to leave the pile unclosed. 

 Under these circumstances, both wires were equally attacked and cor- 

 roded, in the same manner as if a single piece of iron had been put 

 into water ; for, after the lapse of a couple of hours, the polar wires 

 were seen to be surrounded by light flakes of oxide of iron. 



Third fact. 



A piece of iron being voltaically associated with zinc, was exposed 

 to the action of the atmosphere. Having left this voltaic pair for some 

 time to itself, the iron part of it appeared to be covered with a thin 

 layer of rust ; and on comparing it with a piece of iron which had also 

 been placed within the atmosphere during the same space of time, I 

 could not see any notable difference between the states of the surfaces 

 of both pieces. 



Fourth fact. 



A piece of iron wire was connected with each of the poles of a vol- 

 taic pile, without making the wires touch each other. Being exposed 

 to the action of the atmosphere, under these circumstances, both polar 

 wires appeared, after some time, equally aff'ected by rust, and just so 

 as another piece of iron did which was not connected with a pile. 



Fifth fact. 



A piece of iron, being voltaically associated with zinc, was put into 

 common water, so that both metals took up their place within the same 

 vessel. Though I have kept that voltaic pair within water these last 

 twelve months, the iron part of it does not appear to be in the least 

 oxidized, its surface being perfectly brilliant. 



