294 SOSMAN AND HOSTETTER.* REDUCTION OF IRON OXIDES 



of the first series of heatings is given in Table I. The furnace 

 was then cooled, and the residual gas pumped out. The charge 

 was again heated as recorded in the second part of Table I. 

 The results are shown graphically in figure 1. 



TABLE I 

 First Series 



First Series 



Second Series 



It is evident from the figures of Table I that a reaction is going 

 on at 1000° and higher which is supplying gas at a fairly steady 

 rate, and that this rate is greater, the higher the temperature. 

 The changes in weight of charge and crucible, given in Table II, 

 indicate that this reaction consists in the liberation of oxygen 

 and the solution of metallic iron in the platinum. When heated 

 in air after cleaning, the crucible showed on the inside the char- 

 acteristic reddish black color which appears on heating platinum 

 contaminated with iron. 



It is also evident that a small amount of gas absorption takes 

 place as the temperature is lowered, since the pressure decreases 

 more than can be accounted for by the cooling of the furnace 



