> 
( 477.) 
v,,¢m diameters of the rings in m.m. 
x, mean of 2 diameters on plates taken before and after ain. 
First ring: 
# = 9.662 @> 245.410 
0.160 
ty, — 3.640 On == 13.200 
Second ring: 0.171 
en 4608 Pe == 6.802 
0.182 
an BAS Ws a 6/620 
0.171A, A 
A 14, = ——— = 0.0086 A. E. 
ee i 
In the case of the triplet of the mercury line 5770 no displacement 
of the central line could be found. In a field of 28250 the following 
values of the diameters were obtained with the 5 m.m. étalon: 
First ring Second ring 
2.199 3.409 field off. 
2.193 3.408 field on. 
2.199 3.394 field off. 
Kr 
Hence the central line of 5770 remains within the limits of experi- 
mental error exactly in the position of the unmodified one. 
Physics. — “Contribution to the theory of binary mixtures,’ XII. 
(Continued). By Prof. J. D. vaN per WAALS. 
In the discussion in the preceding contribution on the question 
whether there is any possibility that values of v >>b, might occur 
in the case that the locus of the points of intersection of the curves 
dy dp 
—- == 0 and =O is a closed curve, we have also discussed 
dx? dv? 
(p. 433) the case that (g") or: 
dA dA 
n—1—nyY {\A—a@—( s=YVy jA4+(1—2)—| = 0 
dz da 
would be imaginary over the full width from #=0 to e=1. We 
have reduced this equation there to the following form: 
n—1—ne pe ee mn = (1 — 2) pa oe 0 
a a a a 
and shown that if „>> 2, the value of a,—cx* may become 
negative for the high values of rv. The limiting value of x is then 
32 
Proceedings Royal Acad. Amsterdam. Vol. XI. 
