( 641 ) 
(see fig. 95). It is a matter of course, that in fig. 7 the critical curve 
C.C, or rather C,J/", again turns back in that case, consequently 
presents a minimum; equally the critical curve M'C, will not 
seemingly eut CC, between C, and M" in this case, but remain on 
the left of C,. This case occurs e.g. with mixtures of water and 
triethylamine, where in consequence of the almost complete unmis- 
cibility of the iwo components above the lower critical point the 
threephase-pressure will be but very little smaller than the sum of 
the vapourpressures of the two components. So KurreEN found, that 
at 93° C. the threephase-pressure was 142,6 cm., whereas the vapour- 
pressures of triethylamine and water were resp. nearly 86 c.m. and 
58,6 em., consequently together 144,6 em. 
5. It is worth remarking, that the region of the threephase- 
pressure continually shrinks the more we ascend to higher alcohols 
(Kurnen). In the case of C,H,-+C,H,OH the temperatures in 
M' and M" were resp. 31°,9 (46 atm.) and 40°,7 (55 atm); 
in that of C,H, + C,H,OH these are 38°,7 and 41°,7; in that of 
C,H, + isopropylalcohol ? and + 44°; in that of #-butylalcohol 
38°,1 and 39°,8 (55 atm.). Finally with isoamylaleohol three phases 
were no longer realisable, so that the critical points Q coincide 
there with the critical points P, one continuous critical curve being 
formed from C, to C, (General type III). 
In agreement with this is the fact, that the anomaly of the 
alcohols decreases, as these are higher. In fact, we approach then 
more and more the ease of mixtures of normal substances, where 
only at very low temperatures (see my preceding communication) 
a formation of two liquid layers can present itself. KurreN found 
indeed, that C,H, + ether mix in all proportions, whereas C,H,-++H,O 
again present a threephase-equilibrium. 
The influence of the fact that the alcohol is higher is also sensible 
in the case of mixtures of CS, and different aleohols. So we find for 
the upper critical points of CS, with CH,OH, C,H,OH, C,H,OH and 
C,H,OH successively +40°,5 (Rorumonp), —10°,6 (Kuenen) —52° (K.) 
and —80° (K.). : 
Equally the influence of the hydrocarbon was examined by Kuenen. 
While, as we saw above, the separation between type I and II in 
the case of C,H, + different alcohols was between CH,OH and 
(equilibrium between two solid phases and one liquid phase). This will obviously 
also be the case with an upper critical point, as appeared from the experiments 
of Scureinemakers with water and phenol. We will return to this question 
in § 8. 
