539 



may express tlie results combined sub 1°, in the following way. 



There exist three types of P, 7'-diagrams ; the five phases form 

 the anglepoints of: 



a) a convex quintangle (fig. 1) ; then in the P. T'-diagram the 

 live curves form five "onecurvical" bundles (fig. 2). 



/;) a monoconcave qviintangle (fig. 3) ; then in the P, 7-diagram 

 the five curves form two "twocurvical" and one "onecurvical" 

 bundle (fig. 4j. 



c) a biconcave quintangle (fig. 5); then in the /*, 7^-diagram the 

 five curves form one "threecurvical" and two "onecurvical" bundles. 

 We can apply the obtained results also in the following way. 



When we know the position of the five curves of a P, T-diagr^ra, 

 then we can easily determine to which of the types 2, 4 or 6 this 

 diagram belongs. Hence follows at once the position of the five 

 phases wiih respect to one another, \iz. whether they form the 

 anglepoints of a convex, monoconcave or biconcave quintangle. 



We shall discuss now an example of tlie partition of the curves, 

 starting from a quiutuplepoint as is found experimentally in the 

 system: water, CuCl^ and KCl. In this system occur as solid phases : 

 AXV, ChCI,.2HJ) and the doublesalts : CuCI,.2KCI.1Hj) and 

 CuCI^-KCI. We use the following abbreviations: CuCl,-2H,0:^Cii,; 

 CuCl,.2Ka.2H,0 — Bi.o am] CuCh.KCl= Dx.x- We represent by 

 G the vapour, which consists in this system of wafer only. 



In fig. 7 the equilibria, experimentally defined, are represented ; 

 for the sake of clearness this figure is strongly schematized, otherwise 

 it would have to be much larger e.g. the point Cu^ is situated far 

 too close to the point CuCI.,, the point Z)|.2.2 far too close to the 

 side CuCI^ — AT//, etc. Yet we ha\e taken into consideration that 

 the different points which we have to consider, form together in 

 fig. 7 the same quintangles as this is really the case. 

 At the temperature T :=56.1° occurs the equilibrium: 

 rx+ A.2.2 + A.i + Lj^G 

 at Tij = 93.3° occurs the equilibrium : 



AXY+ i), ,.., + /Ji.i + U + G 

 As the vajjour G consists of water only, in fig. 7 the points IF 

 and G coincide. 



Of' course five curves start from the point/, they are: 

 {Cu,)f = D,o. + fii.i + A +G 

 [ü,.,:.2)f=Q,, +A>,.i +A +6^ 

 {Dr.,) f = Cu, + A.Q .2 -i-L + Ö 



(A);-' =6X + A.2.2 + A.i + (? 

 {G)f := CU, + A.2.2 + A»! 1 + A 



35 



Proceedings Royal Acad. Amsterdam. Vol. XVI If. 



