300 



SCHREINEMAKERS 



ART. H 



or phase-complexes (systems) contains the same amounts of the 

 components W and X. As we have taken ee' < ee" < ee'", 

 and consequently Ei has the smallest f , Ei is the most stable, 

 according to the theorem of Gibbs mentioned above. Therefore 

 Es and E2 may change into Ei, but the opposite transformation, 

 i.e., of El into E2 or Es, is not possible. So in general we may 

 say: of all phases and systems, the f-points of which are situated 

 perpendicularly above one another in the (f, a;)-diagram at 

 constant temperature and pressure, that one is the most stable 



l¥ z 



Fig. 4 



which possesses the lowest ^-point. In the following con- 

 siderations we shall make frequent use of this principle. 



5. We now assume that the curve W'X' of Figs. 4 and 5 

 represents the f-curve of a series of liquids. This curve may be, 

 as in Fig. 4, at all points convex towards the composition axis, 

 or, as in Fig. 5, partly convex and partly concave. A point e 

 of Fig. 4 may represent not only the single liquid phase e but 

 also an infinite number of systems of two liquids, e.g., of the 

 Hquids a and 6, or of z and u, etc. We call these the systems 

 L(a) + L{b), or L(z) + L(u), etc. The ^point of liquid e is 

 represented by the point e' of the ^--curve, that of L(a) + L(6) 

 by the point e" of the hne a'b\ and that of L(z) + L{u) by the 



