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 numl)er of organic compounds 
experimented upon in Parts I. and III., has been found capable of correlating a 
number of additional physical phenomena of wide difierence of origin. It is hoped to 
continue these applications to other Ijranches of optics including spectral series and 
optical activity. 
(XII.) [Added Fehruariy 28,1920 .—It has been established that the intermolecular 
field, in all crystalline media, is of the order 10^ 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 Imlanced 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).] 
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