Theory of Gases to the Properties of Diatomic Gases. 395 



In A the two atoms revolve in continuous contact under their 

 mutual electric attraction; in B and C they are separated by the 

 centrifugal tendency. In B the two atoms are describing elliptic 

 orbits about their common centre of inertia, while in C they describe 

 hyperbolic or parabolic orbits. In the set C the atoms may thus bo 

 regarded as practically free. We may also contemplate the possibility 

 of multiple molecules. 



The individuals of the three fundamental sets may change from 

 time to time ; but we may suppose that a permanent average distribu- 

 tion will finally obtain. 



The proportions of molecules in the three classes must be deter- 

 mined by the consideration that the velocities satisfy the conditions 

 appropriate to the specified class. There is no discontinuity in the 

 case of B and C, and the limits of integration for these have been 

 determined. I have not obtained a satisfactory estimate of the pro- 

 portion of A to B, as a sort of discontinuity occurs. Inasmuch as the 

 electrical energy of the two atoms when close together is very great 

 compared with the mean kinetic energy at ordinary temperatures, the 

 molecules are mainly of the class A. 



It has thus been established that a small proportion of molecules 

 are always dissociated, a point which has recently been established 

 experimentally. I also find that although on the whole the numbers 

 of B and C together diminish as the pressure decreases, yet the pro- 

 portion of C to B increases as the pressure decreases. This would 

 account for the increased ease with which electrical discharge takes 

 place through a gas under reduced pressure. 



Passing next to the magnetic properties it is shown from a former 

 paper* that diamagnetic effects are produced by the free atoms on 

 establishing a magnetic field, and that the effect disappears very soon. 

 It is also shown that the molecules contribute positive magnetic 

 susceptibility ; and the formula obtained, which is complicated, agrees 

 well with Quincke's experiments on the subject. 



Turning to the dielectric constant, it is found that 



K = l+kp/d 2 , 



where p is the pressure, the absolute temper \ cure, and h is a 

 constant depending on the gas. This differs essentially from other 

 theories which have been proposed, as regards the temperature varia- 

 tion, the usual result being 



K = l+kpjO. 



We may see without analysis how this arises. The electrical field is 

 capable of affecting the rotational energy of the molecule, and thus the 



* " On the Phillips Phenomenon," ' Electrician," August, 1899. 



