Voltaic Condition of Iron, 277 



iron ; but when the foil was slipped off from the iron the gas 

 then rose from the iron and continued to do so, but the metal 

 was not thrown into action. 



When two glasses were filled with acid and connected by 

 a compound platina and iron wire, the platina or inactive iron 

 in one glass exerted a protecting influence on the iron in the 

 other, provided the communication was first made through 

 the galvanometer : a touch, however, with a common iron wire 

 threw the metal into action, producing a strong electrical cur- 

 rent. The same was the case when three or four glasses con- 

 nected by a compound platina and iron wire were employed. 



But the most curious fact that I observed was this: the 

 nitric acid was diluted with water till it had a sp. gr. of 1'204«. 

 In this acid iron was not protected by platina even when coiled 

 thickly round it ; on the contrary, it appeared to me that ox- 

 idation took place with increased rapidity when the platina 

 was in connection. Neither was the iron protected when the 

 connection between the metals was made through the medium 

 of the galvanometer, provided that the iron was dipped into the 

 acid^rs^ ; but if the metal was f?^st connected with the galva- 

 nometer and then put into the acid, no action whatever ensued 

 in any length of time, even after the platina was removed : but 

 once touching it with another piece of iron always threw it 

 into action, it becoming instantly covered with a brown nitrate 

 of iron ; the wire thus made inactive did not possess the power 

 of rendering other wire so, but was always thrown itself into 

 action when common iron wire was substituted for the platina, 

 whether it was connected with the galvanometer frst or not. 

 The first wire in this case acted as platina and the second as 

 zinc with regard to the electrical effect that was for the 

 moment produced. 



When two cups were used in this experiment and the con- 

 nection between them made by a bent common iron wire the 

 result was the same, the platina in one cup protecting the iron in 

 the second. The conditions before mentioned being observed, 

 if now the inactive wire was made active, electrical action 

 was produced, the current being conveyed across the connect- 

 ing wire. Things being in this state, if the connecting wire 

 was removed electrical action ceased ; and if a fresh wire was 

 bent, and one endijlrst dipped into the cup containing the ac- 

 tive wire, and then the other end put into the cup containing 

 the platina, that end was immediately in the 2^eculiar state. 

 Now here there was no metallic connection whatever between 

 this wire and platina, still it was preserved inactive, and there 

 was also no passage for the electrical current, for the needle 

 of the galvanometer was quite still ; but when by touching with 



