Molecules of Hydrogen, Oxygen, and Nitrogen. 22 1 



Oxygen. 

 Determining the coefficients h, g from the observed 

 refractivites //< — 1 of oxygen gas for the lines H a , H y , 

 which, at normal temperature and pressure, are 2*697 and 

 2-747 . 10" 4 , I find, with lf=32 and d = 1-4294 . 10" 3 , 



6 = 3'967; ^ = 2-50. 10" 10 , . . . (0 2 ) 

 whence k=b 2 /g = Q'297 . 10 10 , 



i.e. P = 3-149. 10 10 . Thus the smallest integer fulfilling 

 the condition (13) is, in the present case, k = 2 (which 

 happens to coincide with the "valency" of oxygen). Con- 

 sequently we shall attribute two dispersive electrons to each 

 oxygen atom, 



£ = 2e=3-66.10 10 (0) 



Substituting these values of h and k in (12), we have 



< 7 & = 0-5446, (19) 



again satisfying amply the condition of stability (14). This 

 value, together with the above b, g for 2 , substituted in (8) 

 gives, for the atomic coefficients of oxygen, 



& =1-413; <7o = 0-549 7 .10- 10 , . . . (20) 



and for the free wave-length belonging to an oxygen atom 



\ = 6-226. 1()- 6 cm. = 622-6 A.U. . . (21) 



From (19) and the first or! (20) we have o- = 0'3840, 



whence, the distance of the two atoms in a molecule of 



oxygen, 



11=1-265. 10" 8 cm {22) 



This again coincides with the semidiameter of the oxygen 

 molecule *, as found by the methods of the kinetic theory of 

 gases, viz. : 



Viscosity. Heat-conduction. Diffusion. 



1-405 1-29 1-35. 10" 8 cm. 



In this case the distance R differs from the heat-conduction 

 value even much less than this does from the viscosity and 

 the diffusion value of the semidiameter. 



Nitrogen. 

 The observed refractivities for nitrogen gas (N 2 ) at normal 

 conditions are 2982 and 3'020.10~ 4 for the lines H a and 

 H Y respectively ; J/=28-02, d = 1*2507 . 10~ 3 . Proceeding 

 as in the former case, 1 find from these data 



6 = 4-409; 0=1-91. lO" 10 ; * = - =10'20. 10 10 , (N s ) 



i. e. ^ = 5*10 . 10 10 . The smallest integer, therefore, 



* As it should do if, say, the spherical atoms are in contact with one 

 another. It will be remembered that R is the mutual distance of the 

 " centres " of the atoms. 



