22 LETTEES OF BEEZELIUS 



the circuit is not closed exactly in the order I have 

 described, the nitric acid acts on the wire in the 

 usual chemical manner. If an iron wire which has 

 in any way been made indifferent is connected with 

 the negative pole of a battery, it is instantly attacked 

 by the acid with violence. But the most remarkable 

 fact of all, a fact which no one, so far as I know, has 

 ever observed, is this. The positive iron wire is not 

 only not- acted on~ky the acid, but it is not even 

 oxidized by the oxygen which is set free at its surface 

 by the decomposition of the water, which should 

 occur according to the accepted theory. The oxygen 

 appears as a gas on the iron just as it does on a wire 

 of silver or platinum, and the metallic surface is not 

 altered in the smallest degree. This liberation of 

 oxygen on the iron wire occurs in the most dilute as 

 well as in concentrated nitric acid, if, as I must once 

 more repeat, the circuit is closed exactly in the order 

 I have described. If you employ an acid of specific 

 gravity 1*36 diluted with ten times its volume of 

 water, and close the circuit, for example, with the 

 negative pole, not the smallest bubble of oxygen 

 appears on the iron wire forming the positive pole ; 

 on the contrary an iron salt is produced which sinks 

 down in yellowish-brown streams. The same occurs 

 even in acid diluted with 400 times its volume of 

 water. But if the end of the iron wire which has 

 been plunged in the acid is held only for a few 

 seconds in the air, and then the circuit is closed with 

 it, the oxygen again appears on its surface in the 

 gaseous form. If the iron terminal from which 



