96 
be possible to characterize anthropologically the different races of men 
by indicating the differences in the character and the intensity of 
the processes of transformation. 
And if the vertebral column should be chosen for such an inves- 
tigation, an opinion about the degree of organisation attained would 
certainly not rest on too narrow a basis, as the vertebral column is 
in contact with many organs that surround it, and actively or 
passively participate in its transformation. 
Physics. — “On vapour-pressure lines of binary systems with widely 
divergent values of the vapour-pressures of the components.” 
(In connection with experiments of Mr. Karz). By Prof. Pu. 
KOHNSTAMM. (Communicated by Prof. vaN DER WAALS). 
§ 1. General character of the vapour-pressure lines derived from 
the differential quotients. The theory of the p‚z-lines of binary mixtures 
was developed by van per Waats in Verslagen Kon. Ak. v. Wet. 
(3) 8 p. 409 and These Proc. III p. 163 (See also Cont. II p. 120 
et seq.) on the supposition that the quantity u 
2, occurring there may 
Ay 
ad — 
x . Ene 
be represented by een and so is only dependent on the critical 
at 
temperature of the mixture taken as homogeneous. VAN DER WAALS 
showed later on that a further approximation may be obtained by 
the introduction of the quantity pe, the vapour-pressure of the 
mixture taken as homogeneous. Then: 
dlp. 
3 Wea 
— (je ail ii). 
Pk ft 
In a recently published paper*) I showed that a number of 
particularities of the vapour-pressure lines follow from these equations. 
Since then Mr. Katz’s investigations *) and the results communicated 
while : 
obtained was */, R. It was mentioned during the discussion at the Conseil Sotvay, 
Nov. 1911 that Professor KAMERLINGH Onnes and myself had undertaken an inves- 
tigation of y,,, by Kunpy’s method for hydrogen at temperatures down to that of 
liquid hydrogen, but this investigation has not yet been completed. 
1) Zschr. f phys. Ch. 75 p. 527. 
2) These Proc. Vol. XIII p. 958. 
