5ri9 



fact pleads in favour of lliis supposition, hut that on the contmiy 

 the observed phenomena make this supposition highly improbable. 

 Nevertlieless it is iiere of some importance to consider also this case, 

 in vidiich the curve PQR then would indicate in what way the 

 temperature of the transformation homogeneous mixed crystals -^ 

 mixed crystal phase + compound varies with the concentration. 



To arrive at perfect certainty about the interpretation of the 

 phenomenon, the ternary system H.,0 — NaCl — KCl was studied 

 at 25° and atmospheric pressure, for so far as this was necessary 

 with a view to the question under investigation. 



C^Cf 



Aa 



Fig. 2. 



If no compound is found, and if D and E in Fig. 2 are the 

 mixed crystal phases coexisting at 25°, we shall have to do with 

 two solubility-isotherms PQ and QR, so that Q is the solution that 

 coexists with the two solid phases D and E. If we start from two 

 concentrations a and h, on the lefthand and the righthand of the 

 top Q, (see Fig. 1), it is clear thai these two mixtures, which are 

 homogeneous at temperatures above 407°, will consist of the two- 

 phase complex D -\- E 2^. 25°, but in different ratio. 



