280 E. L. Nichols — Chemical Behavior of Iron 



regia and nitric acid, the speed of reaction within the magnetic 

 field differed very little from that occurring under ordinary cir- 

 cumstances and the character of the reaction in the two cases was 

 almost identical. The rise of temperature under the influence 

 of the magnet, however, was found to be slightly in excess of 

 that produced when the magnet was not in action. In order to 

 bring out the magnetic influence more clearly than could be 

 done with the magnet described in the first paragraph of this 

 paper a larger one was constructed. The core of the new 

 magnet was 25 mm in diameter, and each arm was wound with 

 840 turns of No. 18 copper wire. This magnet afforded a 

 field many times as strong as that of the small one. With it 

 the reactions of hydrochloric acid upon iron were repeated and 

 all the remaining experiments of the investigation were made. 

 Considerable difficulty was found in obtaining concordant 

 results with hydrochloric acid, owing to the frequently incom- 

 plete solution of the iron. The desired rapidity and complete- 

 ness of action were however finally secured by using 50 c.c. 

 of the undiluted acid upon two grams of iron at an initial tem- 

 perature of 40°. Measurements under these conditions and with 

 the larger magnet corroborated the results of the first series, 

 and were free from the irregularities which had vitiated those 

 determinations. 



HCl 



HoS0 4 



Table IY and curves "j " and " k," figure 3, show the range 

 of temperature during these reactions. 



