( 192 ) 



water, alcohol and suecinonitrilo, two liquid layers only appearing' 

 in the binary systems water-siiccinonitrile, and alcohol-succinonitrile 

 but not in the system water-alcohol. A second example, which Dr. 

 SCHKEINEMAKERS has now Subjected to an investigation is the system : 

 water, phenol and aniline ; in the system phenol-aniline there do not 

 appear two liquid layers, in the systems water- phenol and water- 

 aniline there do. Yet the isotherms acquired in both systems are 

 entirely different as shown in figures 1 and 2. In fig. 1 the letters 

 W, A, N indicate the components water, 

 alcohol, succinonitrile ; in fig. 2 the com- 

 ponents are water, aniline and phenol, 

 indicated by the letters W, An and Ph. 

 In both systems we shall only consider 

 part of the appearing equilibriums viz the 

 appearing liquid phases that can be in 

 e(iuilibrium with each other ; the equili- 

 briums in which solid phases appear are 

 not considered here. 



Let us begin with the system : water, 

 alcohol, succinonitrile ; at temperatures 

 above 5G°5 only homogeneous liquids are 

 possible and no separation into two layers 

 can appear. The ^-surface in fig. 1 above 

 the triangle W A A^ is consequently in 

 every point convex-convex downwards. 

 Here and in future we only consider the 

 sheet of the ^-surface that belongs to the liquid phase ^). When 

 the temperature falls there appears at 56°5 a plaitpoint and at 

 lower temperatures a plait is developed ending on the plane W N ^ 

 and continually extending in case of a fall in the temperature. In 

 fig. 1 d is the projection of the plaitpoint at 56°5 ; the different 

 lines drawn, each of them ending in two points of the line W N 

 are the connodal lines at the different temj)eratures ; they are all 

 situated in such a way, that those belonging to lower temperatures 

 lie outside those of higher temperatures. In case of a fall in the 

 temperature the plait from the side W N extends more and more. 

 At ± 32° there appears however a second plait on the ^-sufrace, origi- 

 nating in the plane A N ^^ iu a point, the projection of which is 

 indicated by e ; consequently we now get at a lower temperature 



') Vid. J. D. VAN DEii Waals, Proceedings of the lioyal Ac.idemy of Amsterdam 

 1897, 209. 



