nL, and (hat of the mixed crystal series BB^, represented by the 

 cnrve hL, for a deiinite temperature, so that the point of intersection 

 L indicates the saturate solution coexisting with the mixed crystal 

 phases A^ and i>,. 



We imagine the solutions hei'e also in equilibrium with their 

 vapour, in consequence of which the pressure is therefore not constant. 



The vapour isotherm belonging to the solubility isotherm aL is 

 the line u^G, that which belongs to the solubility isotherm liL is 

 denoted by h^G, so that G represents the vapour phase coexisting 

 with the saturate liquid L and the two solid phases A^ and _B, at 

 the four phase equilibrium. 



If now CL^L^ represents the isotherm of the internal equilibrium 

 in the liquid phase, i. e. the line that indicates how the internal 

 equilibrium between A and B in the liquid phase shifts through 

 change of the concentration of the solvent 6', we see immediately 

 that as this line cuts the solubility isotherm of the mixed crystal 

 series AA^ (point L^), in case of internal equilibrium between A 

 and B of all the saturated solutions only the saturate solution Z„ 

 is stable, which then of course will coexist with a mixed crystal 

 phase which is like\\ise in internal equilibrium, and is denoted here 



by A,. 



Besides these also the isotherm of the internal equilibrium in the 

 vapour CG„G^ is indicated. This line cuts the vapour isotherm 

 iiiG in Ga, so that it immediately follows from this that in case of 

 internal equilibrium of all the saturated vapours only the vapour 

 G^ is stable, so that the phases J„, L^, and (t^ coexist in the stable 

 three [)hase equdibrium solid-liquid-vapour. 



It is known that the concentration of an arbitrary i)liase can 

 immediately be given. Thus the concentration of the liquid phase 

 L„ is found by a line being drawn in this point parallel to the side 

 CB, and another parallel to the side CA. as this has been done 

 in fig. 1. One line meets the side AB in h, and the other in k. 

 The number of gr. mol. A to 1 gr. mol. total or ,r is now given 

 by Bh, the number of gr. raol. J3 or y by Ak, and the number of 

 gr. mol. solvent C or 1— .r — i/ by A/.. 



I may further assume as known that if our end in view is oidy 

 the ratio of the concentrations ^1 and H, e.g. in the same point L, 

 this is also directly found when a straight line is drawn through 

 the points C and L. This line meets the side AB in the point (/. 

 The ratio of the concentrations of A and B is the same in every 

 point of the line Cd, hence it is in (/ also the same as in L. lu 

 (/ this ratio is : 



