1004 



Mr. Gr. H. Livens on a Theory of the 



density of the electrons exciting- the band under considera- 

 tion. The particular case chosen is that for which e x 2 = 2 



6c 2 (o' 

 and a = 1/3; the dotted lines represent the curves for -p % i 



and the continuous ones the other function. In figures 2 

 and 3 the maxima of ^ 2 , which are not exhibited, are 



Bn? 



respectively 28 and 2800. 













Fig 



'.1. 



































\ 













/ 



'' 





\ 

 \ 



. 









-=^^ 



^ 



X 





"-. 







"5 



r -<? 



f 



~'J 



\ 



"I 



J 



\ 



\ 



i 



y i 



f 





<*=7U 





















c 



_2 



























The lowest point of the continuous curve always occurs for 

 a positive value of #< \/3/, and the maximum point of the 

 dotted curve for a negative value of x between and 



These diagrams illustrate very vividly the important 

 characteristics of the phenomena. The presence of the 

 absorption band in general causes an increase in the rotation 

 on its more refrangible side and a decrease on the other side, 

 even to a reversal in sign. The decrease is in general much 



