( 879 ) 
kind we have comparatively few data as yet: we have collected 
what is known of it, in table VII. The second column (7') gives 
the temperatures of the critical end-point, the third that at which the 
point of inflection is observed. 
It is seen that the existence of points of inflection in these lines in 
the neighbourhood of critical end-points is of general occurrence, also 
when the two components are normal non-associating substances. 
In the system aniline + cyclohexane it even exists up to 50° above 
the critical end-point. If we wished to insert all the known cases of 
points of inflection into the table, also when the measurement was 
made far from the critical end-point, a great number might probably 
be added to the list. It is indeed difficult to see how one should 
conceive the course of these p,c-lines without points of inflection. 
Already in 1901 one of us') drew attention to the existence of 
points of inflection in the p,v-tines of ether’) with little volatile 
substances in opposition to a thesis of Osrwarp, who denies the 
possibility of such points of inflection for the general case, so even 
for components which associate in the liquid phase or act chemically 
upon each other’). The systems mentioned here are new proofs 
which refute this thesis. 
3ut they prove more. As one of us derived lately from the theory 
of Van per Waats, p‚v-lines with fwo points of inflection are to be 
expected under certain circumstances. There he only showed under 
what circumstances a p‚z-line will occur which is convex downward 
on the two sides, concave in the middle, and adds to this: “Den 
umgekehrten Fall, eines konvexen Teiles zwischen zwei konkaven, 
den man erhaiten wird wenn /, << /,, habe ich bis jetzt noch 
nicht gefunden, doch es ist kein Grund mehr vorhanden, ihn als 
unmöglich zu betrachten.” The measurements published here about 
the system hexane and aniline confirm the rule found theoretically. 
For if we try to draw up a p,a-line for e.g. 73.°30 from the data 
of table IV, we can hardly give it another shape than the one just 
described, Direct experimental determination of the p,«-line itself, 
however, remains desirable. 
At any rate there is now one reason more for the warning given 
loc. eit, that from the somewhat divergent course of the p,r-lines 
from the prevailing type we are not yet justified in coneluding to 
the existence of a dissociating compound, as is often done. In the 
1) Pa. Kounstamm. Z. phys. Ch. 36 p. 41 (1901). 
*) Raoutt, Z. phys. Ch. 2 p 353 (1888). 
3) Lehrbuch der allgemeinen Ch. Il 2 p. 642. 
) Po. Konnsramm. Z. phys. Ch. 75 p. 550 (1910). 
