614 Mr. Bernard Cavanagh on 



Thus by (8) 



L — T-iAj&a _<£o 



/9oa_*o\ (3() 



3T vm 0fl 



(ii.) The three Specific volumes of the three phases of the 

 pure solvent 



1 _ Vo 



p m ' 



By (7) 



And similarly 



I = _ T |/M (31) 



Po dp \m J 



I— i^ - 8 - 

 W Pot" m o 



Now for the virtual change {$n 0a + $n } as we have seen 



— 8nn : Sn = — : — • 



m o a m o 



And by (21) we have for equilibrium between solution in the 

 first phase and pure " solvent" in the second 



*5.-_*o -* jlog (l + ^ + ^/.-^l } -0 (33) 

 m 0a m ra e (. & ' Lr d<iJ -> 



— at temperature T and pressure j». 



Making 2^ vanish we get pure " solvent " m &o£/i phases, 

 and the condition for equilibrium at temperature T and 

 pressure p reduces to 



Clearly therefore (T — T ) and (p—po) being small *, 



* When they are not snmll the right-hand side of (34) has to be 

 treated as a differential and integrated "by means of known equations 

 expressing the physical behaviour of the pure "solvent." Similarly 

 with (35). 



