22 AET. 10. — K. IKEDA I STUDIES ON THE 



or taking the logarithm 



'"^'' = ir{^~T) ^'-'^ 



This equation is inaj^plicable to cases in Nvhich Ci is very small, 

 because then Pi will be very large and cannot be well expressed 

 by the simple equation {A). But in other cases Ci can be 

 calculated from the boiling point by equation (12). 



If we express the sum of molar fractions of all the involatile 

 components by C, then Q = 1—C, and we get 



-ln{l-C) = ^^(2-^i) (13) 



T— Ti is what is called the elevation of the boiling point, and 

 increases with increasing C. Equation (13) might well be employed 

 for the determination of the molecular w^eight, etc. in the cases 

 where the solution is not dilute but approximately ideal. When 

 the solution is very dilute, C is very small in comparison with 

 unity and we may write C instead of —In (1— 6'), and Ti instead 

 of TT^, and equation (13) passes into 



which is the well known equation of van t'Hoff. 



§ 3. Equilibrium between Ideal Solutions and 

 Pure Solids. 



The problems of the equilibrium between solid and liquid 

 phases are full of interest. Yet the treatment of them has hitherto 

 been almost exclusively qualitative, the exceptions being those 

 cases which could be solved by the theory of dilute solutions, 



