CHEMICAL THEORY OF SOLUTIONS. PART I. 77 



dy _ ^ ^ fix 



.(61) 



9C 

 liave seen by equation (39) that 



hence 



We have seen by equation (39) that ~~^ is always positive, 



4^<0. 

 ax 



Only at x = 0, -g^ = 0, hence 



(^).-«' 



while at the other end where 

 z = 0, 



ÈL = (^-1)^1 < 0. 



dx 6'« (v-1)' 



v6ß V 



Fis. 18. 



The equifractional curve for 61 must, therefore, have a form 

 shown in Fig. 18, being coucave to the axis of x at least for 

 the smaller values of x. 



(b) The JEquilibriiim between Gaseous and 

 Liquid Phases. 



As the form of the surfaces of the partial vapour pressures 

 at a constant temperature can be readily deduced from the 

 surfaces of the molar fractious we need not describe them in 

 this place. As to the surface of the total pressure it is re- 

 presented by the equation 



which may be written 



