741 



along the satnrationeurve under its own vapour-pressure increases 

 from h and decreases from n. Further we find Ihat lliis curve must 

 have in tlie vicinity of n and Ji a direction as in fig. (XI). As 

 further tiie pressure in k is greater than in n, tlierefore on this 

 curve as well a point of maximum- as a point of niiniinumpressure 

 must be situated. Consequently, we obtain a curve A ?ï, as in fig. 6 (XI), 

 this does not disappear at tlie tempeiature 7//, hut it forms a curve, 

 touching tlie side BC in H. 



2. F melts with decrease of volume {V <iv). Now the points 

 H and H^ are no more situated, as in the previous case, between 

 F and C. From the binary equiUbrium F -\- L -\- G it follows that 

 H is situated between F and B, the point H^ may be imagined as 

 well between F and C as between F and 7i. In the last case //j 

 should be situated between F and H and tlierefore very close to H; 

 the region L — G should then be very narrow in the vicinity of the 

 side BC, which is only possible in very exceptional cases. Therefore 

 we consider only the first case: /^ is situated between 7'^ and B, 

 and H^ between F and C. 



If we take two points n and h close to H and the corre- 

 sponding points ?ii and li^ close to H^ then we see that /S and S^ 

 have an opposite sign. If further we keep in mind that A F is 

 negative between F and H and positive in the other points of BC, 

 then it follows, in a similar way as above, tliat curve nh must have 

 a form as in fig. 5 (XI). Therefore, it disappears at Tu in the i)oint H. 

 Consequently, we obtain a diagram as in fig. 5 (XI), but with this 

 difference, that H is situated now between F and B. 



Contemplating the boilingpointcurves of ?^, we obtain diagrams 

 as fig. 5 and 6 (XI), the arrows must then however, indicate in 

 opposite direction. Further we must imagine the point of maximum 

 temperature H to be replaced by the point of maximum pressure 

 Q of the binary equilibrium F -{- L -\- G. A IF is negative between 

 F and Q, positive in the other points of BC. From the position of 

 Q and Q^ with respect to F, it follows that S and S^ are both 

 positive. We distinguish two cases. 



a. S^ S^. We find that the boilingpointcurve hii has a form as 

 in fig. 5 (XI) ; the arrows must, howexer, indicate in opposite direction. 

 Therefore, this curve disappears under the pressure 7^q in the point (2' 



/;. S<^S^. The boilingpointcurve hu has a form as in fig. 6 (XI) ; 

 the arrows must, however, indicate in opposite direction. Therefore 

 the curve does not disappear in Q under the pressure P^. 



If we sum together the results obtained above, we have : 



