( 599 ) 
direction of channel rays which he led through it, he photographed 
at the same time 1. the normal lines of the hydrogen at rest and 
2. the strongly shifted lines of the hydrogen-ions in motion. *) 
And so finally it appears that the relative tranquillity of the sun, 
never disturbed by terrible eruptions, as has been proved so clearly 
by numerous important solar phenomena and has been demonstrated 
especially also in the last year by the rotation-investigations of ADAMs, 
Hare and Fox, *) is not even in contradiction with a Dorrie shifting 
of the spectral lines of the Protuberances. 
Delft, the 18* of January, 1909. 
Physics. — “On the course of the isobars of binary mixtures.” 
By Prof. Pu. Konnstamm. Communicated by Prof. J. D. van 
DER WAALS. 
1. In these Proceedings of June 27th 1908 van DeR WAALS 
ais dp dp 
showed that only if a’,,< a, a, the curves ae = 0 and ae Q can 
touch for volumes larger than 30, the critical volume of the mixture 
taken as homogeneous. On the supposition a,a, —=a’,, the point of 
contact lies at a value v = 6. Now at higher temperature the well-known 
diagram of isobars (These Proc. IX p. 630) leads to the intersection 
d D 
of the two branches of Ree on the line Dadian = 0, which takes 
dv dv du 
place at the minimum critical temperature of the system under dis- 
; ee dl ses 
cussion. Then the line aa = 0 divides into two branches, which we 
av 
can now denote as the lefthand branch and the righthand branch. 
5 dp 
The lefthand branch necessarily intersects the line —-—=0 in two 
At 
; 4 dp 
points, and as it contracts more and more, while the line — = 0 
wv 
moves towards the right with increase of temperature — tbe asymp- 
p 8 : k da ‚dd 
tote of this locus being given by 7 MEI — contact must 
av Ak 
take place, and that for a volume larger than that for which the line 
1) StarRK: Astroph. Journ. Dec. 1906, p. 362. 
2) Apams: Astroph. J. November 1907, April 1908. — Hare: ibid. April 1908. — 
Fox: ibid. Sept. 1908. : 
