274 E. L. Nichols — Chemical Behavior of Iron 



The open tube was attached to a water vacuum-pump and 

 after an elapse of five minutes the temperature of the acid was 

 noted. The bell jar was then raised, two grams of iron 

 were thrown into the acid and the bell jar replaced. The 

 vacuum-pump removed all fumes as soon as formed. The 

 temperature of the rapidly effervescing solution was noted at 

 intervals of thirty seconds until the reaction was complete. 

 The violent character of the reaction made all stirring of the 

 solution unnecessary. In order to detect the influence of the 

 magnet a, series of these experiments were made in which, as 

 already stated, all other conditions were maintained unaltered 

 and the magnet was alternately active and inactive. 



HNO3 + HCI 



When iron is dissolved in aqua-regia the character of the re- 

 action varies greatly with the strength and temperature of the 

 acid. At low temperatures and in weak acid, hydrogen is given 

 off' and the solution at the completion of the reaction is green- 

 ish, containing for the most part ferrous chloride. 



At higher temperatures the reaction is more violent, red 

 nitrous fumes are evolved and the resulting solution is yellow 



