278 E. L. Nichols — Chemical Behavior of Iron 



effervescence, and a cloud of red nitrous fumes was given off. 

 The removal of the solution from the field of the magnet re- 

 stored the passivity of the iron, and. the action, in a few 

 seconds, ceased entirely. All attempts to destroy the passivity 

 by further stirring failed, until the beaker was brought back 

 into the neighborhood of the magnet, when, at the merest touch 

 with the thermometer, or any glass rod, the reaction would 

 begin again and continue until the beaker was removed from 

 the field. It was found possible to render the iron passive and 

 to destroy that passivity at will by the above process; and 

 after the solution had become warm the reaction was found to 

 begin spontaneously whenever the beaker was brought into the 

 field. 



HN0 3 2. 



The temperature at which the reaction begins spontaneously 

 in the field was 60°, a point which probably varies with the 

 strength of the acid and the character of the iron. 



The further study of this curious phenomenon, which seems 

 to be akin to the influence of the voltaic current upon the pas- 

 sivity of iron, described by Schonn* and by Renard,f was laid 

 aside until a more powerful magnet could be procured. 



*L. Schonn: Poggendorffs Annalen, Erganzungs Bd. v, No. 2. 

 t A. Eenard: Comptes Rendus, t. 79, Nos. 3, 5 and 7. 



