SOSMAN AND HOSTETTER: REDUCTION OF IRON OXIDES 299 



Nearly twice as much iron was deposited in the same way in a 

 similar crucible, which was similarly treated and tested. In 

 this case the iron was deposited chiefly on the inside of the cruci- 

 ble near the bottom, whereas the iron of Table IV was distributed 

 uniformly over inside and outside. The results of the second 

 test are given in Table V. 



TABLE V 



TREATMENT 



Crucible tested alone 



Iron deposited electrolytically 



Heated at 1400° and 0.001 mm, 

 for 5 min 



Heated at 1400° and 0.001 mm 

 for 5 min 



Cleaned in HCl, dried 



Heated at 1400° and 0.001 mm 



for 10 min 



Heated at 1400° and 0.0005 mm 



for 10 min 



Heated at 1400° and 0.0007 mm 

 f(5r 10 min 



TOTAL 

 WEIGHT 



mg. 



3235.6 

 3285.9 



WEIGHT OF 

 IRON IN 

 CRUCIBLE 



3280.4 



3280.3 

 3278.8 

 3279.2 

 3279.55 



3279. 6^ 



mg. 





 44.8 



44.8 



44.7 



43.2 54 



MAGNETIC 

 PULL, 



43.2 

 43.2 



43.2 



mg. 



0.0 



1110. 



80. 



60. 



2.56 

 1.57 



1.46 



REMARKS 



Deposit weighs 

 50.3 mg. but con- 

 tains hydfogen, 

 carbon, and 

 moisture. 



Unabsorbed iron 

 near bottom. 



Thin unabsorbed 



film remains. 

 Film removed. 



Crucible stuck to 

 furnace tube. 



Crucible stuck to 

 furnace tube. 



Figure 2 shows that the magnetic effect is very nearly pro- 

 portional to the weight of the deposit of iron, before heating has 

 driven it into the platinum. (The first point of the curve 

 represents a preliminary plating of crucible No. 3) . 



The immediate drop in the magnetic effect as soon as the iron 

 diffuses into the platinum is very evident from Tables IV and V, 



'" The crucible stuck to the furnace tube ; the gain in weight is probably due 

 to rhodium absorbed. 



