the Thermo-dynamiccd Properties of Superheated Steam, 85 



Since the variation (cKp) = 0, it is possible to integrate at once 



for the case of superheated steam Thomson's formula for the cooling 

 effect c, which may be written 



cIt _ dv 

 T ~ y + cKp ' 



the resulting equation being 



V + cKp _ 



T 



when A may be a function of the pressure. This equation has been 

 used to find the specific volumes of superheated steam under various 

 conditions of pressure and temperature, the value of A being deduced 

 from known data in the saturated condition of the steam. 



The calculated specific volumes, the accuracy of which depends solely 

 on the experimental results obtained in the research, are compared 

 with those obtained experimentally by Hirii, the results in general 

 agreeing very well. 



It is also of interest to notice that in any gas in which does not 

 vary with the pressiu'e, the product cK^^ must also be independent of 

 the temperature in that particular gas, since the equation 



|(K,)=-|(cK,) 



must be satisfied identically, and hence the equation 



V 4- cKp _ dv 



must be immediately integrable for the gas in the form 



v + cKp _ 



— ^ — - f{p)- 



