258 PROCEEDINGS OF THE AMERICAN ACADEMY. 



In these last data the absorption took place to 162 millimeters. 

 Combining this with the expansion to 160, the mean is 161 millimeters. 



With the same charge the following data were then taken at a higher 

 temperature, after admitting some nitrogen. 



June 27 



Here the pressure had nearly reached the equilibrium value, as it 

 was decreasing very slowly. In order to get equilibrium from the 

 other side, some nitrogen was pumped out. 



The equilibrium therefore lies between 274 and 271, the mean of 

 which is 273 millimeters. The mean temperature was 1278° C. 



There was a great 'deal of white powder on the walls of the furnace 

 after this long heating. 



The following run was made using a heating spiral of twice the 

 cross- section and half the length, heated by a direct current. 



The equilibrium was approached only from one side, when the ex- 

 periment was stopped on account of poor regulation of the tempera- 

 ture by this arrangement. The equilibrium found was 283 millimeters 

 at a mean temperature of 1308° C. 



Experiment 12. 



The object of the following experiment was to measure an equilib- 

 rium between 1000° and 1100°. Since equilibrium could not be ob- 



