CONSTITUTION AND TEMPERATURE ON MAGNETIC SUSCEPTIBILITY. '289 



(XI.) It is considered that the above conclusions when conjoined with those 

 obtained in Parts I., II., III., which bring the theory into line with the magnetic atom 

 fields of RITZ and probably suggest an origin of spectral series, amply justify the 

 importance of the magnetic forcive in crystalline and vitreous media. The magnitude 

 of this local magnetic forcive, first calculated to interpret the change of diamagnetic 

 susceptibility observed on crystallization of a large number of organic compounds 

 experimented upon in Parts I. and III.; has been found capable of correlating a 

 number of additional physical phenomena of wide difference of origin. It is hoped to 

 continue these applications to other branches of optics including spectral series and 

 optical activity. 



(XII.) [Added February 28, 1920. It has been established that the intermolecular 

 field, in all crystalline media, is of the order 10 7 gauss. The electrons, within the free 

 atom, are controlled by electrostatic, and possibly also by magnetic, forces, whose 

 origin lies in the core. When the atoms are grouped into a definite space lattice, the 

 cohesive force between them is of a magnetic nature, and the rigidity of such media 

 is due to the localised mechanical stress, exerted at definite points across the atomic 

 "surface" ; the electrons revolving in small circles in adjacent atoms (p. 274). This 

 mechanical stress, due to the local magnetic forces, is responsible for the change of 

 specific susceptibility, and other properties, on crystallization ; and is balanced by the 

 stress due to the distortion of the internal electrostatic configuration of the atoms. 

 In this way, a balance is secured between the electrostatic and magnetic stresses ; 

 these stresses predominating alternately, as we pass through the crystalline structure, 

 thus giving rise to a system in equilibrium. 



The rotation of electrons in small circles, at definite points near the atomic 

 " surface," is suggestive in connexion with the theory of directed valencies required 

 .to explain stereo-chemical phenomena (p. 274, footnote).] 



