1894.] 



of Gases at Constant Volume. 



393 



calorific capacity of the gas between the initial temperature and 

 100 C. 



! The following empirical equation expresses the line /> = (H24 cal- 

 \ cnlated into a line of variation of specific-heat with temperature : 



C v = a + 26 (100 )+3c(lOO ) 2 , 



where t is the initial temperature of the experiment in centigrade 

 i degrees; 



a = 0-19020000. 

 6 = 0-00006750. 

 C = 0-00000182. 



Theoretical considerations led Bankine and others to predict a 

 deci-ement of the specific, heat of a gas at constant volume with rise 

 of temperature. The characteristic-equation of carbon dioxide does 

 not seem to have been given as yet in a satisfactory form for ap- 

 plication to the higher pressures. Probably on this account only an 

 approximate agreement is found to exist between the numerical 

 amount of the decrement predicted and that observed experimentally 

 at the higher densities. At the lower densities the sensible 

 absence of variation with temperature over the range of the observa- 

 tions is in perfect agreement with the theoretical numbers. 



* Liquid present up to 21, q. p. 

 t ,, 1&, q- P- 



