850 



lil the case sub a the pressure of the binarj equilibrium ^-|"^~l~^^ 

 increases from C along CB and from A along AB up to B (fig. 2). 

 On increase of pressure the points /i and n shift therefore towards 

 B -. under Pb (the pressure of the minimum meltingpoint of B) the 

 boilingpointcurve disappears in B. 



In the case snb h one of the binary equilibria B-{-L-\-G has a 

 maximum pressure^ represented in fig. 3 by the point Q. Consequently 

 the pressure increases from C along BC up to Q and from A firstly 

 along AB and afterwards along BC up to Q. Under pressures lower 

 tlian P/j the boilingpointcurves have therefore one extremity on AB 



and one on BC between C and Q; 

 under pressures between Pjj and 

 pQ the one terminating point is situ- 

 ated 'on BQ and the other on CQ. 

 In the vicinity of the point Q the 

 boilingpointcurves may have two 

 kinds of form. In fig. 3 we have 

 assumed that they disappear in Q 

 on increase of pressure. In the other 

 case, which the reader may draw 

 easily himself, there is one touching 

 the side BC in Q and they disappear in a point within the triangle. 

 A part of these curves has then necessaiily a point of maximum- 

 and one of minimum temperature. 



From the position of the boiling point curves in the vicinity of 

 the point Q it follows that S^S, and therefore also y^:ij^x,'.x 

 is assumed or in words : if we add to the binary equilibrium B-\-L-\-G 

 situated on the side B C {x — o) the substance A, its perspective 

 concentration is greater in the liquid than in the vapour. If we consider 

 that A Wy is positive between Q and C, and negative between 

 Q and W, then it follows from (5) or (7), that on the boiling point 

 curves in the vicinity of Q the temperature must increase in the 

 direction of the arrows. 



In the case sub c both the binary equilibria B -{■ L -\- G have a 

 point of maximum pressure, represented in fig. 4 — 6 by the points 

 (I and Q' . We distinguish three types : 



1. in the vicinity of the one point of maximum pressure [Q fig- 4] 

 SyS,; in the vicinity of the other [Q'fig^] S<CS,. 



2. in the vicinity of both the points Q and Q' , S <i S, (fig. 5). 



3. in the vicinity of both the points Q and Q' S > S, (fig. 6). 

 In each of these diagrams the pressure increases therefore along 



BC from B and C to Q and along BA from B and A to Q' 



