616 Mr. Bernard Cavanagh on 



which is easily seen to be the " Perfect Gas Law " of van't 

 Hoff, as obtained of course in Planck's simple treatment, but 

 only, as already pointed out, for a simple non-associated 

 "solvent "such as is considered in this section. 



(2) Concerning the dependence of ~~ on Concentrations — 



Solute- Separation- Data. 



For each solute-molecular species we have from (24) 



M =<£>,. — jaTioo- --loir (1 + £*W2r*»'Ml 



On s 



ogd + ScO-S^j 



We have two main types of data to deal with : (a) Partition 

 data which includes solubility data ; (&) E.M.F. data in 

 the special case of Electrolytes. 



(a) For partition data to be of much use the condition 

 and behaviour of the solute considered must be simple (or 

 accurately known) in the second phase. 



Thus it may be alone in the second phase as in solubility 

 data, or it may form a " perfect solute " in the second 

 phase, L e., 



^ "a pi Cs « 



=0 — ii lOD-- = 



as for a constituent of a mixture of perfect gases. 



This is the case to a close approximation in the gaseous 

 phase, in dilute solutions of non-electrolytes, and in non- 

 conducting dilute solutions of electrolytes. Then for the 

 equilibrium partition, 



i. e., at constant temperature and pressure 

 "dfx i c-s 



Thus 



^g=^i^-^i+k +CaB,,fc 



: ~dc s 



=^'Ag, • (36) 

 So that %(f) x ' ^ can only be obtained after extrapolation to 



OCs 



zero concentration unless A — - etc. are already known. 



OCs 



