592 Mr. Clive Cathbertson on the 



C 2 = 0, that the complete solution is given by 



V x =— { {s — a)e- n ^ t cosfat + oL 1 )+(s — &>- n2 'cos(a> 2 £ + a 2 ) j, 

 Y 2 =p 2 a® | <?-^cos («!« + ft) -«-"»* cos fat + 2 ) J , 

 q i== _5*5 |ft, 1 (5-a)^-^sm(a) 1 f + 7 1 ) + a) 2 (5-5)^- J ^sin(a) 2 ^H-72)| J 

 C 2 =|> 2 a^ | -co^-^ sin fat + SO + cD 2 e- n ^ sin (© 2 * + &) j , 



where » 9 = 1 ^ 1 T -=&K 1 M as before, and 

 K 2 Li 2 



7i = 4:^ — f, 72=- 4 72 — b» 



-6 



in which f=a\ 2 — foVx 



C*©! " C"G> 2 





Wi 7l 2 



and «i=7i— TT^ a 2 = 72~ — » 



©i © 2 



'A=*i-jJS ft=S 2 -^ 







LX. On the Refraction and Dispersion of Gaseous Com- 

 pounds, and the Cause of the Divergence from Additive 

 Relations. By Clive Cuthbektson *, 



IT is well known that the refractivities of simple gaseous 

 compounds do not follow an additive rule so closely as 

 those of solids or liquids. The refraction equivalents of 

 Gladstone and Dale and their followers were found to be 

 fairly constant, at any rate for the same class of compound. 

 But, in gases, the discrepancies observed are much wider ; 

 and this appears the more surprising since, in other fields of 

 research, the gaseous state has proved peculiarly favourable 

 for the discovery of simple relations. 



With the object of investigating the cause of these ap- 

 parent anomalies the writer has, with the help of others, 

 measured the refraction and dispersion of a number of 



* Communicated by Prof. A. W. Porter, F.K.S. 



