( 234 ) 
Physics. — “On the influence of the pressure on the miscibility of 
two liquids .” By Dr. J. Timmermans and Prof. Ph. Kohnstamm. 
(Communicated by Prof. J. D. van der Waals). 
1. Survey of earlier experimental investigations. 
A survey of the experiments on the influence of the pressure on 
the miscibility of two liquids, has often been given ’); so we shall 
confine ourselves here to some short remarks. 
If we leave Alexejeff’s experiments which were unsuccessful, 
out of consideration, Klobbie and de Kowalski are to be considered 
as the first that have worked in this department; they succeeded in 
showing qualitatively the influence of the pressure on the miscibility. 
Further Kcenen has carried out a systematic series of investigations, 
which has remained up to now the most important contribution to 
our knowledge on this subject. And lastly van der Lee and BOchnkb 
have subjected two systems of particular importance to a closer 
quantitative investigation, while Buchner found at the same time a 
great number of new systems. 
It appears from all these investigations that the influence of the 
pressure on the miscibility is slight on the whole, as it is, indeed, 
almost always the case in condensed systems, in which no vapour 
phase is present. 
The theory of these phenomena comprises also the study of the 
different possible forms of the saturation curve of a binary mixture, 
on which two liquid phases are in equilibrium. We confine ourselves 
to calling attention first to Rothmund’s supposition *), according to 
which all these saturation curves might finally be reduced to t e 
type of a closed curve, as it is realized in the system nicotine and 
water; then to that of Timmermans 3 '), on the possibility of “negative 
e doctorate, Amsterdam, 1898, and Zeitschrift 
1 ) N. J. van der Lee, Thesis for I 
fir physikalische Ghemie. 33, 622, 1898. . ... , 
Buchner. Thesis for the doctorate, Amsterdam, 1905, and Zeitschrift fur p y 
ische Ghemie. 56, 257, 1906. . in( i 
J. P. Kuenen, Philosophical Magazine (6), 6, 637, 1903, and Verdampfung^ 
Gasgemischen (Bredigs Handbuch der angewandten pnysu^ 
' 2) V. Rothmund, Thesis for the doctorate, Munchen, 1898, and Zeitschufl f 
physikalische Ghemie, 26, 438, 1898. ua 1907 and Bulletin 
3) J. Timmermans, Zeitschrift fur physikalische Ghemie, 58,144,190 , 
de la Soeiete chimique de Belgique, 23, 129, 1909. 
