419 
second virial coefficient when the empirical equation of state is written 
in the form: 
By Cn Dr . En — Fy 
PUN — AN oe ar Fo ain ee (1) 
UN UN EN uN° vn® 
while the subscript y indicates that the volume is expressed in terms 
of the normal volume as unit (ef. Suppl. N°. 23, Chapter on “Units’’). 
Values of Ly were taken from the corresponding individual values 
of B which were given in previous communications by KAMERLINGH 
Onnes, and by him in collaboration with BRAAK, with CROMMELIN, and 
with W. J. pr Haas. As we must remember that the latter coefficients 
Bs, belong to the empirical equation when written in the form of 
equation (II) of Comm. N°. 71 (June ’01), and that the subseript 
a has there a meaning quite different from that attached to it in 
Suppl. N°. 23, they will be in the sequel distinguished as AGT 
The reduction is then made by means of the relationship 
Ban) 
/ 
Aar) 
BN = (2) 
It was first examined for each of the different gases if the tempe- 
rature variation of 6 is in agreement with that deduced on the 
assumption of rigid molecules (ef. Suppl. N°. 24a § 3 for spheres of 
central structure, § 4 for ellipsoids, ef. also p. 255 note 1 of that 
Suppl.) and van per Waats attractive forces. This assumption gives 
| awn | 
Poh 3 
| ay es ig (eat alt 6 Ke 
(ef. Suppl. N°. 24a $3 equation (14), where ayy, bwy and Fy are 
constants. For this investigation /’, = log (J—r), in which t= = 
bywnRxT 
is now plotted as a function of logt on transparent squared paper 
to the same scale as before. But log r is now taken as increasing 
in the opposite direction to that in which log 7 inereases in the 
previous diagrams. 
For comparison with the assumption that the molecules of a gas 
behave as if they were rigid molecules of central structure each 
with an electric doublet of constant moment at its centre, equation 
(59) of Suppl. N°. 244 $ 6 was written in the form: 
By = bwn. Nl -— (Av)? — , (Avy) - seer et (4) 
i? eased a 75 DEN ar Pa 
Here / and v have the same significance as in Suppl. N°. 24/ $ 6, 
and hwy. is the factor which, for the units now employed, must 
1 4 9 
id xo* of Suppl. N°. 246 $ 6. 
replace the factor 7 
