Thermody mimical Theory of Ternary Mixtures: 949 



From equations (9), (10), (11), and (28) we can deduce 

 immediately the following equations 



Y o <n o ,0)^ +s l Yjn 1 ,8)^ + S2 v 2 (n 2 , 0)^=0, (29> 



O s \ OS\ 0*i 



v (n„, e) ^» + nVxCn,, 0) W± + . 2 v 2 (n 2) *>|5.» =o, (30j> 



5 2 0^2 05 2 



v,(n 1 ,tf)|5t = v,(n»fl)^. i . . (3i> 



If we assume that the vapours behave as ideal gases, i. e.. 

 that 



n l v*Cn*,^)=^...(i=o,i,2) J . . (32> 



nil 



where R is the gas constant and m t - the molecular weight of 

 the vapour of d; and if we write 



c i — 



_ s 2 m 

 m 2 



where c x and c 2 are the molecular concentrations of C a and; 

 C 2 respectively, then equations (29), (30), and (31) become J 



aj^n. + ci Bi^n, + ^ 5 log n 2 =Q _ _ 



()Cl Bc x ^C 2 



5 log I 



C^2 



5 log IIx a logjlg 



3Jf. +ei W + « = 0. . . ( 34> 

 0C 2 (K 2 0C 2 v ' 



*> DcT (35) 



These three equations correspond to the single Duhem- 

 Margules equation for a binary mixture. 



If the component C 2 is involatile equation (30) contains 

 an indeterminate term, and equations (29) and (31) give 



v (n , e)^ + Sl v,(n 1 , e)^.+ tt Y 1 [n u 6) ^ =o. (36) 



Similarly equations (33), (34), and (35) reduce to 



ocj dci dc 2 v J 



We shall return to the consideration of vapour pressure in the 

 next section. It may be remarked here that the three general 

 Phil. Mag. S. 6. Vol. 27. No. 162. June 1914. 3 R 



