Hackett — TJic Ionic Theories of Magnet o-optic Rot nf ion. 2'4 



Comparing 

 but from (5) 



27rW 



c 



ka ' 



where B^ is a constant in the dispersion formuhi 



^1 



71^ = A + 



In practice B^ and h' are expressed in the units corresponding to 

 wave-lengths in 10"^ cm. This does not change their ratio. Ai in the 

 above expression is in cm. AVriting = x lO""*, and assuming 

 that By and h' are expressed in their ordinary form, the results can bo 

 exhibited in tabular form thus : — 



X 

 tH 



tv,-h' 150 

 "^7 ^"^a 



Substance. 







V 



5i for 

 L line. 



Am for 

 Z> line. 





Carbon Bisulphide, . 



•0433 



•045 



•153 



•762 



•042 



3-9 



Creosote, 



•0277 



•0433 



•314 



•745 



•024 



4^3 



k = 3437-75. 



II. 



Calculation of 



Si 



The formula for the rotation on the hypothesis of the Hall-effect 

 can be put in the following form (9) in the case of certain substances : 



. 1 rC B'X' -|_ 



and the experimental constants give a general expression in the form 

 nka \_X' ^ (A'^ - A,2)-J 



