318 



Professor Arthur W. Crossley 



[Feb. 



sulphur), it is rather more active ; whereas, when obtained from the 

 highly purified hydroxide, it is extremely active. 



The following example, also taken from evidence handed into 

 court in the case already referred to, may be cited in further exempli- 

 fication of this point. The iodine value of an oil was decreased 

 from 108*4 to 72 '1 by treatment with hydrogen in presence of 

 nickel obtained by igniting nickel carbonate at 400-450% and 

 reducing the resulting oxide with hydrogen at 400°. A specimen of 

 the same oil liad its iodine value lowered to lo'2 when treated in 



Cc.Hz absorbed 



. P 1 p- 



LiNSEED Oil N T.P Curves 



Effect of Various Proportions of Ni 



FROM Hydroxide 



'S'/o 



Fig. 3. 



presence of nickel prepared from the carbonate by roasting at 300° 

 for 5-6 minutes, and reducing the resulting oxide with hydrogen at 

 300° for 4-5 minutes. 



In other words, it is not only necessary to make a selection from 

 the chemical methods for preparing the nickel, but it is also of 

 importance to produce the metal in a certain physical condition, 

 obtainable by reducing the oxide for a certain length of time at a 

 definite temperature. 



A further very important point is raised by the above curves — 

 namely, the question of temperature, which is not the same for all 

 oils, and which requires to be carefully selected after many trial 

 experiments. 



