86 MR. A. E. OXLEY ON THE INFLUENCE OF MOLECULAR 



The electrons which give rise to diamagnetism also give rise to the Zeeman effect, 

 a slight alteration of their periods accounting for both phenomena.* The order of 

 magnitude of the local molecular field H c will not be effected by assuming that the 

 electrons in a molecule have a mean natural period T,, when the substance is in the 

 liquid state, which becomes modified to r c = T,($T, when crystallization sets in. The 

 change of period Sr indicates the order of magnitude of the displacement of an 

 absorption band owing to the transition from the liquid to the crystalline state. 

 Now 



Xc = ^j. . AM C) Xl = ^ . AM,, 8 X = Xc - x , = |p (AM C - AM,), 



where n is the number of electrons per molecule and N the number of molecules 

 per gram. Therefore 



c|x _ AM C -AM, r,L - -. H \ 

 X ! AM, %A' 



TI/ 

 The change of period ST is produced by the local molecular field H c , and therefore 



Hence 



^i, (12) 



This equation gives us a value of the local molecular field H c when we know the 

 extent to which x is modified on crystallization. With all the substances investigated 

 in Part I. and with many of the elements examined by HONDA and OWEN, 9x/X 

 amounts to a few per cent. Hence either 



j ._ 6 3 . T; 2 . H/ 1 ^_ 6 . T, . H c 



TOW -,c 2 2 r TOT) n ' 



IOTT??! 2-n-m 



Taking T ,=== 10~ 15 sec., e/m = 2 x 10 7 , we get either 



H c = 6 x 10 7 gauss or H c = 3 x 10" gauss, 



and in either case H,. is of the order 10 7 gauss. 



We have no experimental evidence at present as to how far an absorption line is 

 displaced when a substance passes from the liquid to the crystalline state, but such 



* LANGEVIN, 'Ann. de Chim. et de Phys.,' vol. 5, p. 97, 1905. 



