IIackett — The Ionic T/icories of Mayncto-optic Rotatioit. 17 



CllEOSOTE. 



X,' = 0-0340, a" = - 0-070, //' = + 0-380. 



Spectr. Line. 



5 calc. 



5 obs. 



C 



0-573 



0-573 



B 



0-744 



0-758 



E 



0-987 



1-000 



F 



1-222 



1-241 



G 



1-723 



1-723 



From the constant h" obtained by Drude, it is possible to calculate 



D'. Therefore we can deduce the value of — for the ions of the 



Ml 



ultra-violet absorption-band in carbon disulphide and creosote. The 

 calculation is given in Note B. "We get 



— = -53 X 10' for carbon disulphide, 

 nil 



— = -77 X 10" for creosote. 



Ml 



The theory of the Hull-effect leads to a proper value of — in the 



case of carbon disulphide and creosote. It is possible by the same 

 kind of approximation as before to show that in general the value 



of - deduced from the magnetic rotation on this theory is of the 

 m 



proper order. The dispersion formula in general has to take account 

 of absorption-bands in the infra-red also ; and if k be the dielectric 

 constant, we have the following relations : — 



, ^ . <^2V <iiiK^ 



=. A + — 4- — + 



K.I. A. PKOC, VOL. XXVI., SKCT. A.j Ji 



