845 



fig. 1 continue to intersect one another only in one point, under a 

 pressure 1\ the points .s' and d of fig. J coincide in a point n of 

 fig. 2; curve ed is then situated coniplctelj within tlie sector B r s. 

 Now the saturationcurve under its own vapourpressure is represented 

 in fig. 2 by hn and tlie corresponding vapourcurve by Ii^n\ ; the presBuro 

 increases in the direction of the arrows, therefore from n towards 

 h. Consequently Ph is tiie highest and P,, the lowest pressure, under 

 which the equilibrium F -\- L -\- G occurs, h not being however a 

 point of maximum- and n a point of minimum pressure of the curve. 

 Further we see, that on change of pressure, the turning of the 

 threephase triangles Baa^ and Bhh^ is in accordance with the 

 rules formerly deduced. 



We have assumed when deducing the above, that the curves ed 

 and rs of fig. 1 intersect one another only in one point under every 

 pressure. It is also possible, however, to imagine that after the forma- 

 tion of the first point of intersection, a second arises by the 

 coincidence of d and .s' (fig. 1). The li'quidcurve of the region L(r 

 proceeds then in fig. 1 from .s- firstly outside and afterwards within 

 the sector Brs.On further decrease of pressure the two points of 

 intersection shift towards one another and coincide under a pressure 

 P,n in a point iii not drawn in the figure ; the corresponding vapour- 

 point ?7?i is then situated on a straight line with m and B. The 

 pressure P„j is the lowest pressure under which the equilibrium 

 B -\- L -{- G may yet occur; m and m^ are points of minimum 

 pressure of the curves hn and h^n.^. 



It is evident from the manner in w^hich arises the threephase 

 triangle Bbb^ in the vicinity oï BA. that this now must have another 

 position than in fig. 2 ; its conjugation line solid-gas therefore Bb^ 

 must be situated between Bb and BA. Two three-phase triangles 

 situated on both sides of the point of minimum pressure turn there- 

 fore towards one another their sides solid-liquid. 



Tn the two previous cases we have assumed, that the first common 

 point of ed and rs arises by the coincidence of ^ and r. We now 

 assume, that both the curves touch one another in a point M 

 situated within the triangle; the corresponding vapour point M^ is 

 then situated on a straight line with M and /)'. The pressure Pm'is 

 the lowest pressure under which the equilibrium B -\- L -\- G occurs. 



On decrease of pressure two points of intersection of ed and ?'.s" 

 now arise; the one disappears, when r and e, the other when d 

 and s coincide. We then obtain again a saturationcurve under 

 its own vapourpressure as hn and a corresponding vapourcurve as 

 hji^ in tig. 2 ; the points, M and M^ , which are not drawn, are 



