( 638 ) 
To the considered type also belongs SO, + H,O, C,H, + H,0, 
and equally ether and water. This latter mixture only with this diffe- 
rence, that the composition of the vapour-phase is here continually 
between that of the two liquid phases (see. fig. 3%). Kuenen *) found, 
that at 201° the vapour-phase coincides with that liquid phase, which 
consists for the greater part of ether. The threephase-pressure is then 
52 atm. (At C, we have 7, =195°, p, = 38 atm.). 
The p, z-diagrams would now show a maximum-vapourpressure, 
if the two liquid phases 1 and 2 could become identical. In 
connexion with this the threephase-pressure will be higher (here only 
some mM) than the vapourpressures of each of the components, and 
it follows immediately from fig. 1, that the critical curve C,C,, or 
rather CM, will at first run back from C;, that is to say will present 
a minimum critical temperature. In the ease of C,H, + CH,OH, where 
the composition of the vapour-phase is without that of the liquid 
layers, the threephase-pressure will always be between the vapour- 
pressures of the components. 
3. Now, as to the representation of the so-called transversal- and 
longitudinal plait on the y-surface at different temperatures (in its 
projection on the v, z-surface) in the case of C,H, + CH,OH, it will 
be obvious, that the critical point Q, considered above, of the longi- 
tudinal plait always lies at the side of the small volumes. For 
increase of pressure finally favours (see above) the mixing. 
The successive transformations of the transversal- and of the longi- 
tudinal plaits are further represented schematically, in agreement with 
the p,-sections, in fig.6. The longitudinal plait, occurring here, 
is regarded by van per WAALS *) and this equally in the ease to 
as a transformed transversal plait. Many 
be considered presently 
questions however, connected with these plaits, lose — as has been 
remarked already by van pur Waars ®) — much of their weight, and 
become of secondary interest, as soon as we succeed im connecting with 
other properties of the components of the mixture the often so com- 
plicated transformations, which may occur at the different plaits. 
And to do this an attempt is made in my preceding communication. 
There I showed, that the ordinary theory of the association is capable 
of representing the different possible forms of the boundary-curves quali- 
tatively, and in many cases even quantitatively. 
4. We will now consider the second of the three principal types, 
1) Z. f. Ph. Ch. 28, 342—365, specially p. 352 (1899). 
2) These Proceedings 7, p. 467 (1899). 
8) Id. 25 Oct. 1902, p. 399. 
