1098 
The type, to which this system belongs has been theoretically 
developed by Bicuner') in his study on systems with limited 
miscibility, in which together with the equilibrium of fluid phases 
a solid phase occurs. It has in common with the system ether- 
anthraquinone, that the melting-point of the less volatile component 
B lies above the critical point of the more volatile A and that the 
solubility of solid B in liquid A is small. The three-phase curve, 
on which solid B coexists with its solution in liquid A and with 
a vapour-phase, intersects the critical curve starting from the critical 
point 1 = G of the first component, giving rise to the first critical 
end-point p. As however the component B has not only in the 
solid state a small solubility in liquid A, but’ also molten B is only 
partially miscible with A, the second critical end-point may arise in 
a way different from that in the system ether-anthraquinone. 
From the triple point of B a second three-phase curve starts, 
giving the equilibrium of-solid B with the solution of A in liquid B and 
with a vapour phase. As the melting-point of B lies above the critical 
point of A the vapour of this three-phase line at high pressures will have 
densities corresponding to a liquid; therefore the line will rise steeply. 
The point of intersection of this curve and the critical line L, = G 
or L, = L, is the second critical end-point. Here two liquid phases 
Fig. 2 
become identical in presence of a solid phase. Figure 2 represents 
the P-7 projection of the space figure of this case. BicHNner has 
found the first experimental instance of this type in the system 
diphenylamine-carbonic acid. The critical end-point q could not be 
determined because the critical pressure was not attainable or did 
not exist. 
1) loc, cit. 
