840 



points of maximumpressin'e. It is evident, that in tliis case we mnst 

 imagine in tig. 2 the side Ba of the three phase triangle Baa^ 

 between Ba^ and BC. 



When we consider in a similar way as above also the cases 

 snb 2" and 3", we find: 



the satnrationcnrves under their own vapourpressure have a 

 terminating point on BC and one on BA (curve hn in fig. 2j. On 

 this curve either a point of maximum or of minimum pressure occurs 

 or there occurs none. Tlie cor-responding vapourcurve is situated with 

 respect to hn in the case sub 1" as /i,?z,, in the case sub 2" as h^n^ 

 and in the case sub 3" as h^n^ (or h^n^). 



Previousl}- we have seen, that the saturationcurves under their own 

 vapourpressure of a ternary and a binary substance F become 

 exphased at temperatures above the minimum melting point of 

 F. At the deduction of these curves for the binary compound F 

 we have seen, that the point of maximum temperature of the binary 

 system F-\-L-\-G takes a prominent position and that these curves 

 occur in the vicinity of this point [point H in fig. 4—6 (XI)]. 

 The same applies also to the saturation curves under their own 

 vapourpressure of the component B\ we shall not discuss these 

 here more in detail as similar appearances occur in the case of the 

 boilingpoint curve. 



Let us now consider the boilingpoint curves of the component B; 

 firstly we take these curves under pressures lower than the pressure 

 in the minimum meltingpoint of B; we then find: the boilingpoint 

 curves have a terminating point on BC and one on BA (curve 

 hn in fig. 2); on this curve, either a point of maximum- or minimum 

 temperature occurs or there is none. The corresponding vapourcurve is 

 situated with respect to hn, in the case sub 1" as h^n^, in the case 

 2" as li^n^ and in the case sub 3° as h^n^ (or h^n^). If it is desired 

 that in fig. 2 the three phase triangles Baa^ and Bbb^ retain their 

 position, the arrows must indicate in opposite direction and the 

 temperature increases, therefore, from h towards n. 



It follows from the previous deductions, in what direction the 

 threephase triangles solid-liquid-gas turn on change of pressure 

 (at constant T), or on change of temperature (under constant P). 

 From this also follows the intluence of a third substance on the 

 pressure (at constant T) or on the temperature (under constant P) 

 of the binary equilibrium B -\- L -\- G. 



We may also deduce these results in the following way. We 



