of Hydrogen and some other Gases. 319 



But since X2 is here not very small as compared with g>, 

 we cannot use Bohr's values for co and r, and consequently 

 n o will acquire a somewhat different value from that above 

 given . 



Thus Bohr's models for hydrogen and helium atoms give 

 by magnetization a diamagnetic polarization, whose values 

 are of a right order of magnitude, provided that there is a 

 definite rotation about an axis perpendicular to the line 

 joining two positive nuclei, the velocity of which is very 

 small compared with the velocity of revolving electrons. 



According to the above results, monatomic and diatomic 

 gases are all diamagnetic, and their susceptibilities can be 

 calculated, provided the models of the molecules are known ; 

 this conclusion generally agrees with the observed facts. 



One important exception is the case of oxygen, which is a 

 diatomic gas. Bat if we assume that in virtue of the form 

 and nature of oxygen molecules, the characteristic rotation 

 is completely absent and the rotational energy of revolving 

 electrons is relatively small, then in place of the expression 

 for susceptibility above given, we have * 



% = 

 3 



gxiW + KT)' 



where &> is the angular velocity of revolving electrons, 

 K the moment of inertia of the electron about its axis, and 

 RT the rotational kinetic energy corresponding to Langevin's 

 paramagnetism. Hence % is positive and varies hyper- 

 bolically with temperature. Thus by assuming particular 

 conditions, the paramagnetism of oxygen gas may be 

 explained. 



In the case of polyatomic gases, the resultant magnetic 

 axis of the molecules is not generally perpendicular to the 

 axis of the characteristic rotation, as in the case of the 

 diatomic gases. In this case, if we resolve the magnetic 

 moment into two components parallel and perpendicular to 

 the axis of the characteristic rotation, the former produces a 

 paramagnetic effect and the latter a diamagnetic ; the 

 observed polarization is the sum of these two effects, which 

 may be positive or negative. Thus the polyatomic gases are 

 paramagnetic or diamagnetic according to their natures. 



^ In the above discussion the molecules are assumed to be 

 rigid and no account is taken of the Langevin diamagnetism. 

 If the small term of this diamagnetism be introduced, the 

 above conclusions do not materially change. 



* K. Honda and J. Gkubo, he. cit. 



