.172 ) 



problem of tlie fourse of the solubilitj curve of a solid in the region 

 (»f critical temperatures was now capable of solution. 



It follows namely from the combination of the two conceptions 

 mentioned above, that the course of the solubilitj curve cannot show 

 anything- remarkable, unless the least \'olatile substance {B) occurs 

 as a solid phase and its melting- point lies higher than the critical 

 temperature of the more volatile substance {A), \\liich for the sake 

 of brevity we shall call sohent. 



We will now consider only the case when the two substances in 

 the liquid state are miscible in all proportions. Then there is in the 

 y>, /, ,?'-diagram a continued critical curve, connecting the critii-al points 

 of the two com})onents. Three ditferent ca^^es may now occur. 



Fis. 1 



Fig. ± 



A — Giis. 



7^= Unsaturafcd sdlutions. 

 t =Su|)i'rsaturatt>(l solutions or 

 solid II -\- vapour. 



B = Uiii-alurated solutions. 

 C = Supersaturated solutions or 

 solid i; -{- ^'^PO"""- 



Fig. 1 and 2 are y>, ^|n-qjections of the representation in space, 

 a is "the critical point of .1, J> of B, while d represents the melting 

 point of solid B. The line ah is the critical curve and C(/ the ^>, Mine 

 for the three-phases equilibrium: solid /^-j-solution+vapour. Further 

 ea is the vapour-tension line of liquid A, fh that of liquid B. 



Now the case of fig. 1 will occur when the solubility of solid B 

 in .4 is comparatively great. In this case the vapour-tensions of the 

 saturated solutions are rather small and so the curve cd lies totally 

 below the critical curve. 



The line cd runs on uninterruptedly as far as the melting point 

 of j5; the series of the saturated solutions of B is not interriq^ted 

 by the critical phenomena of the solution ; the solubility ciu-ve shows 

 nothing remarkable. On the other hand the critical curve also goes 

 on nninterruptedly, the critical phenomena being only those of 

 solutions which are unmtumted of solid B. 



