646 



Fi'orn Tino-j^=<S) then follows : ') 



v = 1.53.10-1* 

 and using this value one obtains from (6) for the moment of the 

 ((uadrnplet ; 



fi, n=2,03.10--'G [electrostatic nnits X c.m^]. 



If the quadruplet is assumed to consist of two positive charges e 

 at a distance d from each other, and midway between tliem a charge 

 — 2(', so that ii^:=hi'd\ and if further <? = the charge of an electron 

 r= 4.77.10-10 (Mii.LiKAN), 0116 finds 



d^ 0,92.10-8 cm., 

 a value whose order of magnitude agrees properly with what the 

 distance of the positive nuclei of tlie two hydrogen atoms within 

 the molecule ^J may be expected to Ite. It is to be kept in view, 

 however, that, properly speaking, with this distance of the cliarges 

 it would not be allowable to assume the charges to be situated 

 intinilely near lo one and the same point, as is done in this paper. 

 By taking account of this circumstance one would presumably tind 

 a smaller vahie of d. 



§ 6. Résumé. 



J. For a system of rigid spherical molecules, whose mutual 

 attraction is equivalent to that of a quadruplet situated at their 

 centres the second virial coeflicient is developed in a series of 

 ascending powers of 7'"'. 



2. Above 0.75 7',„,.f: = o) the dependence of B on the temperature 

 for spherical molecules carrying a quadruplet nearly coincides with 

 that for molecules carrying a doublet and for both ditfers but little 

 from the relation 2? = i? (l V t^"^ ' 



3. The values of B for hydrogen from —100° to +100° C. may 

 be represented with sufficient accuracy by the equation derived for 

 spherical molecules carrying a quadruplet. 



meter of the molecule the value mentioned in the text. For the meaning of the 

 indices N, a and M, of. H. Kamerlingh Onnes and W. H. Keesom. 'Die 

 Zustandsgleichung", Math. Enz. V 10, Leiden Gomm. Suppl. N". 23, Einheiten h. 



1) Calculated from r/«r(,^=0) = 194.5, /^i-;,,,- = 0.576 (§ 4), equation (4), and A;= 

 = 1,37.10-16. 



-) Accoi-ding to P. Debije, Miinchen Sitz. Ber. 1915, p. 1, that distance amounts 

 to 0.604.10—8 cm. Debije's hydrogen molecule is, however, strongly paramagnetic 

 (its magnetic moment corresponds to 10 Weiss magnetons) so that the magnetic 

 properties of hydrogen are not represented accurately by this model, unless one 

 would assume with Sommerfeld, Elster- and Geitel jubilee volume 1915, 

 p. 549, that the electrons in the hydrogen molecule in circulating in circular 

 orbits do not exert a magnetic action, and hence behave quite differently from 

 the electrons which in the experiment of Einstein and de Haas cause the 

 magnetic moment of the iron molecules. 



