262 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



The pressure had become constant, so nitrogen was pumped out. 



The average temperature was 1372°C and pressures obtained from 

 opposite directions were 386 and 389, the mean of which is 387.5 

 millimeters. 



Experiment 17. 



The charge consisted of 23.7 grams of carbide. 



Aug. 5. 



The pressure was rising slowly when the experiment was stopped. 

 The equilibrium is therefore nearer 380 than 370. However, the mean 

 of these two, 375, is taken as the result of this run. The average 

 temperature was 1385° C. The charge had become hard on the top 

 but less so below the surface. 



Experiment 18. 



The disadvantage of the Arsem vacuum furnace for experiments of 

 this kind is that the volume is so great that it takes quite a long time 

 for the solid substance to absorb or evolve enough gas to reach equi- 



