293 



Our |)ievious considerations are all valid in tlie snpposition thai 

 the fonr phases F L^L^ and G are silnated with respect to one 

 another as is indicated in tlie figs 1 — 4. When the four |)hases are 

 situated otiierwise with respect to one another, the reader my deduce 

 all in similar way. 



We now shall assume tiiat the new substance is volatile, so (hat 

 it occurs in the phases L^L^ and G with the concentrations 

 x,.r, and .t',. 



We find with the aid of (7) and (19): 

 M (dT):, = — (1 f a) A V'x, + [aA F, — ( 1 f 6) A V] .r, + ft A F. .r, (36) 

 and with the aid of (8) and (20) : 

 M.{dP):, = — {l+a)AH'x^ + [aLH'~il+b)AH].v,-{ bLH-x, (37) 



wherein 



Mz=i{LH .LV' — LH' .L V):RT 



so that the direction of temperature and pressure of curve E are 

 defined by (36) and (37). 



As A V is very small in comparison with A V' we may neglect 

 in (36) the terms with A V as long as .f, is not very large, then 

 it follows with approximation : 



(dT)x>Q voor '^>yZïl, (38) 



Only for very great values of x, in comparison with .t, and x, 



the term b L.V . x^ in (36) will be of great importance and will be 



approximately 



RT LV RT fdT\ 



^. ' LH .LV' ' AV' \,dPjo ' ^ ' 



In (37) LH is not small in comparison with A//' and tiie term 

 b h H . X, will assert its influence already with values of x, which 

 are not too small. 



Consequently, in general the influence of the new substance on 

 (dl'jx and idP)x will be larger in proportion as the new substance 

 is more volatile and it will assert its influence sooner on idP)x 

 than on {dT)x. 



We may also deduce anything about the position of curve E 

 with the aid of the general considerations at the beginning of this 

 communication. Hence it follows viz that curve El must be situated 

 either between the curves (£,) and (L,) or between {L■^) and (6-') or 

 between (L,) and {G). As in the figs 3 and 4 the prolongation of 

 each of those curves is situated between both the other curves, 

 curve E may go, therefore, starting from point I in every direction. 



