389 
If we finally consider the relative situation of the phases on the 
three-phase line, it appears from what precedes that the vapour phase 
lies between the coexisting liquids up to the highest temperature, 
that the vapour branch, however, closely approaches the branch of 
the liquid rich in ether already before the critical end-point. It is 
in agreement with this that a Pz-seetion brought through the P,7'‚x- 
surface e.g. for the critical temperature of ether yields two curves 
which show decreasing values of — starting from the critical pressure 
& 
of ether, that tbe intersection with the three-phase line, however, 
appears just before the maximum pressure is reached, at which the 
concentrations of liquid and vapour would become the same. 
So in the system ether-water the minimum critical temperature 
predicted by Prof. vaN per Waats lies in the immediate neighbour- 
hood of the axis, and the remarkable point of intersection at the 
critical end-point. 
I intend to repeat this investigation for another system hoping that 
I shall be able to demonstrate both peculiarities experimentally when 
the situation is a less one-sided one. 
Anorg. Chem. Laboratory of the University. 
Amsterdam, Sept. 13 1912. 
Chemistry. — “On quadruple points and the continuities of the 
three-phase lines.” By Dr. F. B. C. Scuerrer. (Communicated 
by Prof. J. D. vaN DER WAALS). 
1, In a previous paper’) I examined the continuous connection of 
the three-phase lines, which occur in BaKuvis RoozEBoom’s spacial 
figure on the most simple suppositions. It then appeared that the 
three-phase lines Sa +Sg +L and Sa + SB + G pass continuously 
into each other, and that in the P,7-projeetion this transition takes 
place by means of a partly metastable, partly unstable curve with 
two cusps, in both of which two three-phase branches touch. I have 
now extended this investigation to the other quadruple points which 
can occur in binary systems; I have, however, postponed the publi- 
cation of it for a long time, because the phenomena which present 
themselves in the most interesting case, are much more complicated 
than in the above mentioned ease, and a full deseription would 
require a great many intricate figures. Without treating the cases 
1) These Proc. 1910, p. 158. 
