AND SCHONBEIN 19 



not been altogether without results. I have observed 

 certain new phenomena which can hardly fail, 

 especially from an electro-chemical point of view, to 

 attract the attention of scientific chemists. They are 

 essentially as follows: If the end of an ordinary 

 iron wire of any size is heated in a spirit lamp until 

 its surface has become blue, and is then put in nitric 

 acid of specific gravity about 1/35, neither the heated 

 nor the other end of the wire is attacked. Indeed, 

 the acid can be heated almost to its boiling point 

 before it acts on the metal, although it attacks 

 ordinary iron even when cold. A similar behaviour 

 is shown by iron filings which have been heated only 

 for a few seconds, that is, until they have assumed a 

 blue colour. Now it is remarkable that the protec- 

 tive power of the heated end seems to extend through 

 any length of wire, however great. I took a wire 

 50 feet long and a line thick, heated one end for a 

 distance of not more than a few lines, and put first 

 this end and then the other into acid of the above- 

 mentioned strength. Under these circumstances no 

 part of the wire was attacked, even when its whole 

 length was allowed to lie in the acid. In order to 

 obtain a reaction it was necessary to heat the liquid 

 at least to 70. I performed similar experiments 

 with iron rods of a considerable size, and always 

 obtained the same result. Another remarkable fact 

 is this : An iron wire which has thus been protected 

 against the action of nitric acid can bring another 

 iron wire into the same neutral condition merely by 

 contact (which need only last for a moment, below 



