SPECIFIC HEAT OF AMMONIA. 395 



The specific volume of the vapor, Vi, was obtained by solving Keyes' 

 equation of state for ammonia, simultaneously with the equation for 

 the vapor pressure as a function of the temperature. The equation 

 of state is:^^ 



RkT a , . 



V = J- - -f ^ (32) 



o no 



i?A- = 4.8177 logio^^. = 0.9S130 ■ — 



V 



a = 34610.1 / = - 1.173 



p in atmos. T in degrees absolute on Centigrade scale. 



V in ccs./gram. 



The vapor pressure equation '^^ is: 



logio/J = -1969.65 r-i + 16.19785 - 0.0323858 J + 5.4131-10-5 r 



-3.2715-10-8 P (33) 



where p is pressure in mm. of mercury, and T temperature on the 

 absolute scale in degrees centigrade. 



The method of solving these two equations is to substitute values of 



V in (32) thus reducing (32) to an equation giving ^ as a linear function 

 of T for any given volume. Equation 33 was solved for p for each 5° C. 

 and these values plotted to a large scale. The straight lines connect- 

 ing p and T were then drawn on the same diagram, and from the point 

 of intersection of each line with the curve, the values of T were read off. 

 Since each straight line corresponds to a value of v, this process gives vi 

 as a function of T and therefore as a function of 9. 



The following tables give the computed values of 2> and Vi as a func- 

 tion of 6. 6 is in °C., p in atmos. and vi in ccs./gm. 



e p 



75 36.697 



80 40.937 



85 45.567 



90 50.553 



95 55.973 



100 61 . 797 



105 68.053 



18 Reference (3) p. 20. Eq. 33. 



19 Reference (3) p. 13. Eq. 30. 



