295 



wtance F and tlie liquids L, and L, tlien proceed alon^ the curves 

 Fqr, L^q^)\ and L^q^)\. When we add o\\\y li(tle of the new 

 substance, then the 3 phases are represented by the points qq^SiuA 

 (7, which we must imagine in the immediate vicinitj- of the side YZ. 



When we put t = .v {i/^^y,)—{j/ — ,V,)-''i + (,'/ — //,)•'', ii»d when we 

 consider x and ?/ as running coordinates, then / = represents tiie 

 equation of the straight line which goes in (ig. 5 and 6 through 

 (/, and q,. 



When tlie point (/ is situated on the line q^q, then ^ = 0; the 

 sign of {(lT)x is then deterniinetl by the terms which have been 

 neglected in (40). 



When q is situated at the right side of the line q^q^ (viz. when 

 we go from </, towards ^,) as in fig. 5, then t^O; when q is 

 situated at the left side of the line (/,(/,, as in (ig. 6, then t<^0. 

 Hence it follows, therefore, that in fig. 5 the temperature iiicieases 

 and in fig. 6 the temperature decreases, as is also indicated in both 

 (igures. 



yr<ö 



Fig. 5. Fig. 6. 



Consequently we find the following: 



when we add to the invariant binary equilibrium ^ (.r = 0) = 

 = F -\~ L^ -\- L.^ -\- (x a substance which is not volatile and which 

 forms mixed crystals with the solid substance F, then 



the temperature rises, when the threephases-triangle solid-liquid 

 liquid turns its concentrated liquid towards the side of the com- 

 ponents-triangle (fig. 5) 



the temperature falls when the threephases-triangle turns its con- 

 centrated solution away from this side (fig. 6). 



Comparing fig. 1 with fig. 5 and tig. 2 with fig. 6, the reader 

 will see that for the change of temperature the same rules are true, 

 independent of the fact whether the new substance forms mixed 

 crystals with F or not. 



