256 ° 
pe in the equation for the constant energy; hence we shall also 
take no account of p, in the determination of the macro-complexion. 
The group macro-complexion is then specified thus: 
n‚‚, unspecified molecules are present in dv, dw, (dq, dry), 
ON 5 . 5 5 in zt ATB 
in which (dq, dr), represents one of the different elements (supposed 
equal) of the space involving the coordinates g, and7,. The equation 
for given energy then becomes | 7 
DS (a) £3 ar) C2 1 B a al > dwn,” ' 
Ent eS, Heh EE) a BGs tld —_ 7 = const. 
dy n'dv, 
As far as the thermal equation of state is concerned the result is 
the same as that obtained for rough ellipsoids, but the specifie heat 
ve 
at constant volume is different, viz. Dn hk, for smooth ellipsoids. 
Physics. —- On the deduction from BourzMann’s entropy principle 
of the second virial-coefjicient for material particles (in the 
limit rigid spheres of central symmetry) which exert central 
forces upon each other dnd for rigid spheres of central sym- 
metry containing an electric doublet at their centre. By Dr. W. H. 
Kersom. Supplement N°. 24° to the Communications from the 
Physical Laboratory at Leiden. (Communicated by Prof. H. 
KAMERLINGH ONNEs). 
(Communicated in the meeting of April 26, 1912). 
§ 5) The deduction of the second virial-coefyicient, B, for material 
points (in the limit rigid spheres of central symmetry) which exert 
central forces upon each other. 
In this section we shall deduce the eqnation of state, as far 
as the second virial-coefficient, B, is concerned (ef. § 15, for a 
system of molecules which act upon each other as if they were 
material particles (in the position of the centres, which are also the 
centres of gravity of those molecules) and with forces which are 
given invariable functions of the distance. All mutual actions other 
than that just described will be excluded. The case in which the 
spheres can be regarded as rigid spheres of central symmetry (§ 3) 
exerting central attractive or repulsive forces upon each other which 
are a function of the distances between their centres, will be treated 
as a limiting case. 
1) To facilitate reference to Suppl. N'. 24a sections, equations and diagrams 
in the present paper are numbered as continuations of those in Suppl. N°. 24a. 
