388 
the observations given in figure 2 and table I of pure ether of the three- 
phase pressure determined with a mixture of about equal quantities by 
weight, and of some ten mixtures of the concentration given in the 
table, that not a single end-condensation of the ether layer can be 
realized which took place at higher pressure than the three-phase 
pressure. This shows us in an indirect way, what we also see directly 
from the locus of the plaitpoints, that there is no intersection between 
plaitpoint line and three-phase line. The relative position of the two 
lines is, however, snch that we are here quite in the neighbourhood 
of the above-mentioned transition case. The inclination of the two 
lines in the critical end-point differs so little that we may practically 
speak of contact here. In the P,7 projection the lines of the initial 
and final condensation of the ether layer have been indicated by 
the same numbers as the corresponding mixtures in the adjoined 
table.*) It is clear that the mixtures 6, 7, 8, 9, and 10 in the neigh- 
bourhood of 160° have yielded the three-phase line as end-condensation. 
In ascending order this was the case up to higher and higher 
temperature. For the mixtures 1 to 5 the end-condensation pressure 
was lower than the three-phase pressure over the whole range of 
temperature; hence there was no question of the occurrence of 
three-phase equilibria with these mixtures. The intersection of the 
line of the end-condensations and the three-phase line must be looked 
for here at lower temperature. 
It is, moreover, clear, from figure 2 that the critical line at the 
critical point A of the ether rapidly proceeds to higher pressure, as 
Prof. van DER WAALS anticipated. Whether the inclination is infinitely 
great or very great in the direct neighbourhood of 7%, of ether, could 
not be ascertained. Also in this respect we may again speak of a 
transition case for this system. For we cannot state with certainty 
whether the minimum critical temperature lies in the figure or on 
the axis, or whether it would lie just outside the figure. The last 
seems, however, the most probable from the given observations. 
When the plaitpoint line is considered in its other projections, it 
appears that in the 7,x-projection the inclination on the ether side 
is very slight, almost zero, and that it continually increases up to 
the critical end-point on increasing concentration. In the graphical 
representation the P,r-projection appears to deviate very little from 
a straight line. 
1) In the table the critical data have been given in bold type, above them we 
find the values of the end-, below them those of the begin-condensations of the 
ether layer. 
