314 



SCHREINEMAKERS 



ART. H 



T(c) a critical solution temperature. This temperature may be 

 higher or lower than T{X). 



16. The line zu2' and the curves hz, zcu and uT{X) divide 

 Fig. 12 into fields, the meaning of which follows from the 

 preceding considerations. At the same time it is apparent 

 that the field zcu, i.e., the heterogeneous two-liquid phase field, 

 does not end at the line zu but extends farther downwards, 

 although in a metastable condition. As the liquids saturated 



Fig. 12 



with respect to X are represented by the curves hz and uT(X), 

 the solubihty of X at T(s) does not change continuously but 

 jumps from z to u. If, however, we also consider metastable 

 and unstable states, then a continuous transition from z to u 

 exists. The saturation curve of X consists, as we shall presently 

 show, of a curve hzgekuT{X) having a maximum temperature 

 in g and a minimum temperature in k. 



In order to prove this, we at first imagine T = T(s), so that 

 (X) in Fig. 11 coincides with s. Besides the two coincident 



