THOMPSON AND LOMBARD. — NITROGEN IN CALCIUM CYANAMIDE. 2G5 



dp 



'di 



Q 



T{v- \\y 



in which T is the absohite temperature, V is the vohime of the carbide 



and nitrogen and \\ is that of calcium cyanamide and carbon on the 



dp 

 other side of the equation, and -— is the pressure gradient at the tem- 



1000 



1100 



1200 1300 1400 



Temperature 



1500 



Figure 5. Plot showing pressures and temperatures at which equihbrium 

 exists. Pressures are in centimeters of mercury; temperatures in centigrade 

 degrees. 



perature 7", Q is found to have the values given in Table IV. The 

 volume Fi is negligible in comparison with V. Omitting Vx the 

 equation may be put in the following form : 



Q = 



rn^dp 



p dt' 



The value of R is 1.99 calories, and the unit in which p is expressed 

 cancels out. 



