773 



S^^t\. Ay A Ki is positive in //, it follows IVoiii (16) that the 

 pressure must decrease on addition of ii tiiinl substance. We see 

 that this is in accordance with the direction of the arrow in the 

 vicinity of h. 



In the vicinity of point h of tig. 3 is d\ "> <S' as follows from the 

 position of triangle Faa^. As ^ T^i is positive, it follows from (16) 

 that the pressure must increase on addition of a third substance. 

 This is in accordance with the direction of the arrow in the vicinity 

 of h. 



In the vicinity of point n of the tigs. 2 and 3 S is negative (we 

 imagine for instance in tig. 2 triangle Fb^i in the vicinity of side 

 BC); as A Pj is positive, it follows from (16) that in both figures 

 the pressure must ino-ease, starting from n. 



Consequently we find : in a terminatingpoint of a saturationcurve 

 under its own vapourpressure, situated between 6' and i/, the pressure 

 decreases on addition of a third substance, when the threephase- 

 triangle turns ils side solid-gas towards BC (tig. 2) and the pressure 

 increases when the threephasetriangle turns its side solid-liquid 

 towards BC. 



As, therefore, at temperatures lower than 7V (ügs. 2 and 3) the 

 pressure always increases, starting from n, and increases or decreases 

 starting from h, we tind the following. When we trace curve nh, 

 the pressure increases continually starting from n towards h (fig. 2), 

 or we come starting from n first in a point of maximumpressure, 

 after which the pressure decreases as far as in h (fig. 3) or we come, 

 starting from n first in a point of maximum- and afterwards in a 

 point of minimumpressure. after which the pressure increases up to /^ 



As in point h of fig. 5 (XI) the pressure decreases starting from 

 h, consequent it is assumed here, that the threephasetriangle turns 

 its 'side solid-gas towards BC. (Cf. fig. 2 and fig. 4 (XI); in this 

 last figure vve imagine however curve h^n^ on side CA). In the point 

 h of fig. 6 (XI) is assumed that the threephasetriangle turns its side 

 solid-liquid towards BC. 



Let us consider now the terminatingpoint /? of the saturationcurve 

 in fig. 5 (XI) and fig. 6 (XI). iVs /i is situated between F and H. 

 L Fj is negative, when the threephasetriangle turns its side solid- 

 gas towards BC, then is ,S > .'\ and it follows from (16) that the 

 pressure increases on addition of a third substance. We then have 

 the case of fig. 5 (XI). When, however, the threephasetriangle turns 

 its side solid-liquid towards BC, then 6'<.t'i and it follows from 

 (16) that the pressure decreases on addition of a third substance. 

 We then have the case represented in fig. 6 (XI). 



