f= Sele (3) 
Vet Di + 147 u ’ 
hence 
, Y 
ali = ey e a ol . (y) 
For the verification of the possible constancy of the ratio (v,— 4,): 2, 
at the triple point we shall try to determine in what follows the 
value of _f, Xu, for every group of homologous elements. It will 
then appear at the same time what law the ratio u, = 7%: 7, obeys, 
about which ratio we now only know that it can vary between 
Di and. 33/5. 
Let us now proceed to examine the different groups of the periodic 
system separately. 
II. The Hydrogen-Helium group. 
a. Hydrogen. 
If d,’ may be neglected at the triple point, it follows from 
tlm derd == Di De, thats: 
d,—2 Tr. D,— 2D 
ES A ned, 
Wath 17 == ol Die 003020 Are dS DS OOF 709 we 
find : 
27 
2y = 1056 X —___ = 0,9734, accordingly y = 0,487, 
18,00 
so that we have according to (a) with m, = 0,437 : 
wanes 0,487 
Speen in i by ee 
1,487 © 
As wv, (expressed in normal units) is = 58,3 X 105 according 
to the subjoined table A, it would follow from this that 4; — 58,3 >< 
POLO Se 08E 480 A05. 
The value 48,5 10-5 has been found directly from 77, and pj (see I). 
We find 2,29 for uw; = 7;: 7,,; hence we have here: 
SiOx By = ee 2,29 1,91. 
x 0447 = 0,973 (1 — 0,143) = 0,834. 
b. Helium. 
As the value of y cannot be calculated here yet with certainty 
from the few data concerning d, and d, (from them a theoretically 
impossible value of y would namely follow, much smaller than 0,5), 
I have calculated the theoretical value from (2). We find 2y = 1 + 
+ 0,038 1/5,2 = 1 + 0,038 X 2,28 — 1,0866, hence y = 0,543. 
„afg 
Proceedings Royal Acad. Amsterdam, Vol. XIX. 
