878 
| Tr Vn iten foun 
Helium 5:2 | 228° | 0, 0806.4" 907543 + 0.56 
Hydrogen 32.3 5.68 | 0.2158 | 0.608 0.604 
Argon 150.65 | 12.27) “Ov4 763" Je DES 0.745 
Xenon 289.7 | 17.02 | 0.6468 | 0.823 0.813 
Acetylene 308.5 | 17.56 | 0.6673 | 0.834 0.858 
Isopentane | 460.9 21.47 0.8159 0.908 0.914 
Fluorbenzene) 559.6 | 23.66 0.8991 0.950 0.933 
We have already repeatedly pointed out, that both the form of 
the function D= fw), and the form of the temperature function 
b= f(T) suggest that the change cf 5 chiefly, probably even exclusively, 
corresponds to a real volume change of the molecules, and that an 
apparent change in consequence of the partial overlapping of the 
so-called distance spheres must be rejected. (See among others IV, 
p. 464). 
That such an apparent change loses all foundation in consequence 
of the non-existence of the relation 6=4m, has been conclusively 
proved by me in my opinion in a later article (These Proceedings 
of Nov. 7, 1914). We found there namely (see p. 611), that in con- 
sequence of the influence of the (infinitely slight) quasi-association 
at v=o the quantity 5 must be diminished by the finite quantity 
R:C. (C= the “constant” of the quasi-association). Considerations 
of another nature made it probable that 4 must, indeed, be identified 
in all cases with the real molecular volume m, at most increased 
by a certain influence sphere. 
2. We have already seen that the found temperature relation 
agrees perfectly with that given by a formuia drawn up by van 
DER Waals already much earlier for the variability of 6, viz. 
[p Hofs + ABI 0=),)\=fRE, Nn SOANEN 
in which A represents the (spacial) constant of the quasi-elastic 
atomic forces, which atomic forces were put proportional to the 
increase of volume b—b,. The quantity f is a coefficient which 
depends on the number of degrees of freedom. 
After substitution of 27’: (Vv — 6) for p+ 4/2, and eliminination 
of A and 7, formula (3) appeared, however, not to satisfy the 
relation 6= /(v) found by us. (See particularly IL, p. 930 in con- 
