643 
- of germination of spores to that of disinfection. Three species were 
examined. With two of them development took place in accordance 
with the formula of the unimolecular reactions. 
The reaction-(germinating) velocity of the third species however was 
‘not constant, but decreased progressively. 
For the same species the orderly progress of disinfection and 
germination do not always agree as to their types (fig. 12). 
Physics. — “On the second virial coefficient for monatomic gases, 
and for hydrogen below the Boyir-point’. By W. H. Kersom. 
Supplement N°. 26 to the Communications from the Physical 
Laboratory at Leiden. (Communicated by Prof. H. KAMERLINGH 
ONNES). 
§ 1. Introduction. In Suppl. N°. 25 (Sept. 12) a comparison was 
made between the experimental data at present available concerning 
the second viriai coefficient, 4, for monatomic gases, and the relations 
for the variation of 5 with temperature deduced in Suppl. N°. 24 
(June °12) from certain definite assumptions concerning the structure 
and the mode of action of the molecules. In continuation of that 
investigation the present paper supplies a similar comparison for the 
monatomic gases, and also, in view of the correspondence obtained in 
$ 3¢ of Suppl. No. 25 between these gases and hydrogen below 
the Boyue-point, for hydrogen, too, in that region of temperature. 
‘Until such time as the theories introduced by Nernst and EINSTEIN 
concerning the application of the quantum hypothesis to the rotations 
of the molecules have been further developed, only the suppositions 
made in Suppl. No. 240 § 5 are of any account as simplified 
assumptions if the specific heats of those gases are taken into 
account; according to those assumptions the molecules behave as 
if they were smooth rigid spheres of central structure, attracting 
one another with a force which is a- function of the distance 
between their centres and is directed along the line joining their 
centres. As was done towards the end of $5 of Suppl. No. 244, 
this function is more closely specified by assuming that the attraction 
potential may be put equal to —r7 where q is a constant’). It 
1) For the present comparison is postponed with the assumption made by 
Tanner, Diss. Basel 1912, in which, for simplicity, the action of the attractive 
force is supposed to be completely localised in a thin concentric spherical shell 
surrounding the molecule supposed spherical. 
42° 
