10 



Proceedings of the Royal Irish Academy. 



The Area of the Ionic Circuits. 



The ionic circuits can, on an average, be regarded as circular. We 

 have then q = 7rr^, where r is the radius of the circuit : and inserting 

 the value for the periodic time deduced above, we get 



.en 



q 2m e 



^ " ~W2^ " 4 m 



For the ions in the ultra-violet absorption-bands of carbon di- 

 sulphide and creosote, the following values were obtained for the 

 radii of the ionic circuits in cm. 







e 









m 





Carbon disulphide, . 



3-9 



1-8 X 10' 



2-9 X 10-6 



Creosote, . 



4-3 



1-8 X 10" 



3-1 X 10-6 



The kinetic theory of gases gives us as an upper limit for the radius 

 of the sphere of influence the value 2x10"^ cm. 



The values for the radius of the ionic orbits are then 100 times the 

 molecular diameter, and their area 10,000 times the molecular section. 

 This is of coui'se an impossible result, and it can also be shown that 

 a result of similar character holds good in general for diamagnetie 

 substances, though satisfactory dispersion-formulae have only been 

 obtained in a few cases. 



It will now be shown that is, in general, of the same order 



as has been already found for carbon disulphide and creosote. 

 We have from (1) 



