"^1 



Lim r =: — , while t and s remain unite, it tollows, when we 



.V 



re])lace also A and C bj their values: 



^.ET.dw = \iy -^)V, ^ ^3V-yv\dP. . . . (10) 



Representing' by A V^ the change of volnme, when one (inantit}' 

 of vapour arises at the reaction l)etween (ho three phases (F', L 

 and G), (10) passes into : 



[)RT . d.G = (7/ — /i) Al\.dP (11) 



For solutions between 6' and F' is // — /^ -^ 0, between F' and 

 B is V — 1^ ^ 0. Imagining a /^, 7'-diagram of the binary system 

 F' -\- L -\- (t, H' is the [)oint of maximum lcm|)era(uro ; h Ci is 

 conseqnently negative between H' and F' , positive in the other 

 points of CI). From this it follows: {>/ — /?) A F, is negative in points 

 between C and H', therefore, for the solutions rich in water; (?/ — /i) 

 A F] is positive in points between //' and B, therefore for the 

 solutions of F' poor in water. 



From (11) it now follows: dP is negati\e for liquids on CH', 

 positive for liquids on H' B. In accordance with our former resnlts 

 conseqnently we lind : along the saturationcurve of a binary hydrate 

 the jU'essure increases from the pure solution poor in water towards 

 the |)ure solution rich in water. 



When P' is one of the components, which are not volatile, e.g. 

 B in fig. 2, then « = and /•?;=1. From (11) then follows: 



RT . dx = (_v — 1 ) A F, . rfP {V2) 



We now imagine a 7^7kliagram of the binary system B-\-L-\-(t; 

 this may have either a point of maximnmtemperature H' in the 

 vicinity of the point B or not. When a similar point does not exist, 

 A Fj is always positive; when a similar point does exist, A F, is 

 positis'e between C and H' , negative between H' and B. As we 

 leave, however, here ont of account points, situated in the vicinity 

 of B, A Fi is positive. As // — I is always negative, it follows 

 from (12) that dP is negative. In accordance with our former results 

 we find therefore: along the saturationcurve of a component the 

 pressure decreases from the pure solution towaitls the solntion free 

 from water. 



When F is the volatile component, as for instance in the e(piili- 

 brinm ice -\~ L-\- G, then « = and /? = 0. The second of the con- 

 ditions of equilibi-inm {]) passes now into: Z^=K. This means that 

 not a whole series of pressnres belongs to a given tempci-atni-e, but 

 oidy one definite pressure, viz. the pressnre of sublimation of the 

 ice. Therefore we find again : along an icecurve under its own 



