( 865 ) 
has proved that the modulus @ corresponds in all respecis with the 
temperature. The mean value of kinetical energy in an ensemble is 
u 
— O and this average value is equal to the corresponding value for 
92 = 
most frequently occurring and ‘stationary system, © can therefore 
be used to define the temperature of a stationary system. 
Groningen, Dec. 1910. 
Physics. — “On vapour-pressures in binary systems with partial 
miscibility of the liquids.” “Vax per Waars-fonds” researches 
N°. 2. By Prof. Pa. Konnsramm and Dr. J. Timmermans. 
(Communicated by Prof. J. D. VAN per Waats). 
(Communicated in the meeting of January 28, 19J1). 
In these Proceedings Vol. 9—11') van DER Waars derived a series 
of conclusions concerning systems of not completely miscible liquids. 
In this communication we shall compare three of these conclusions 
with the experimental data which are to be found on this subject 
in the literature, and with the results of some new determinations, 
which follow here. 
We shall discuss the three following points: 
1. The shape of the p,7-projection of the three-phase curve L,L,G. 
2. The connection between the shape of the plaitpointline and the 
existence of a maximum in the p‚r-section of the surface of saturation. 
3. The occurrence of points of inflection in the p,z-section of the 
surface of saturation specially in the neighbourhood of a eritical 
end-point. 
§ 1. Van per Waats has tried to demonstrate that the p, 7-projection 
of the three-phase line does not intersect the plaitpoint line in a 
critical end-point, but touches it. From this very remarkable results 
would follow. 
a. In the case of splitting-up of the plaitpoint line the three-phase 
pressure would ascend regularly with rise of temperature. As, however, 
. iJ dp . . 
one of us’) remarked already before, EF has a very high value for 
: 
’ 
MEDE SE eV : PER Sat dl 
this line in the case of splitting up of the plaitpoint line é never 
ap 
becomes higher than 0,04 degree per atmosphere ) and so the three- 
1) See also Archives Néerl. (2) XIII p. 249—283 (1908). 
*) J. Timmermans. Handelingen van het 13e Vlaamsche Congres 1909 p. 120, 
