FUNDAMENTAL EQUATIONS OF IDEAL GASES 353 



capable of a considerably more detailed treatment along the lines 

 laid down by Gibbs. Thus it would be easy to include in the dis- 

 cussion the effect of the dissolved gas, and the gas in the gas 

 phase, on the vapor concentration of the vapor emitted by the 

 solvent. For this purpose use would be made of the italicized 

 statement (Gibbs, I, top of page 155) together with an equation 

 for the gas and vapor, such, for example, as (Vila). 



14. Effect of the Presence of a Neutral Gas on Vapor Pressure. 

 The paragraph beginning on p. 154 discusses the old obser- 

 vation that, for example, the vapor pressure of a mixture of 

 water and benzene is about the sum of the vapor pressures of 

 each pure liquid at the temperature of the mixture. Since, 

 however, the pressure on the liquid phase is greater than if 

 either were alone present the liquids must be compressed. The 

 nature of the effect of a pressure applied to the hquid phase and 

 its magnitude may be obtained by applying the equation [272] 

 obtained from equation [92] (Gibbs, I, 87). Taking the tem- 

 perature constant and assuming equilibrium conditions there 

 results 



d^ = {vdp + nidmi)t. (31) 



But 



dt = (Pj dp + (f^) dm,, (32) 



and, since p and Wi are independent variables, 



(33) 





Comparing equations (31) and (32) the latter may be written 

 (f^) =Cf) . (34) (2721 



Similarly it may be shown from [88] that 



/a^A ^_(^) . (35) 



