No\ 



( 128 ) 



p (iy-iy) — I p dv = — ?(*!—«,) — j q dx 



ipdvz=— ?(*-.!!,)- j 5 



e 2 



| p dv — ;> (l> c — V e ) = — J \ qdx — q (a l — ,v t ) . 

 e 2 



For the loop-g-line a\ and ,r, coincide, and for a (/-line but little 

 lower \qdx is larger than q(t\ — a?,). As #, always lies on the left 



2 



of the value of x for which q has minimum value, j q dx ^> q [x l — x t ) 



2 



always holds. From this follows that for the lowest pair of coexisting 

 phases of fig. 21 the straight line must be drawn in such a way 

 that the area of the hatched part above this line, to which the area 

 of the hatched part of fig. 22 is added, is equal to the hatched pari 

 of fig 2J which would lie below this line. So the pressure of the 

 lowest pair of coexisting phases foi I his (/-line is greater than would 

 follow from the application of the rule if the point of intersection 

 of c, g and d,f was an identical point, or rather represented one 

 and the same phase. But we shall not pursue this course any further. 



Now that we are obliged to include the quantity I x dq in our con- 

 siderations, we can find the coexisting phases for the liquid volumes 

 in a simpler way by the aid of this quantity. For such volumes lie 

 on a /(-line which can be followed without interruption when we 

 proceed from one point of the pair of' coexisting phases to the second 

 point. And when we proceed along a /j-line dM 1 (i 1 z= — x dq, and 



so (A/, fi,) 3 — (M, (i l ) 1 = — I as dq. Hence we need only choose two 

 points on the chosen /(-line, satisfying the requirement that — I .cdq = 0, 



?(*!— «l)=J 'I'',,-. 



Then we have to cany out the same construction on the (/-line 



