Rotational Optical Activity in Isotropic Media. 1003 

 are in fact simplified by writing 



/" = x x n i and d = a/, 



and neglecting the term xn r2 in comparison with the term 

 x\*n l2 3 which always accompanies it. We have then 



?1 2 =L + M, ^=L-M, 



e 1 e x 



where L 2 = 1 + 2a 2 -2a sin 26+ 2k 2 cos 26 



M = l-asin20, 



-that eV=6i4 (M!) =aVcos4 , 



e 2 -tc 2 = e 1 2 'M. = e 1 2 (l-asin26). 



We have therefore 



2 — = | (ex 2 - 1) - *e x 2 sin 2<A -fafe 2 - 1) + 1 - aue{ 2 sin 2*"} 

 -4«Vcos 4 ^ 



9/-2 



CID 



i _ {2a(€x 2 - 1) + 1W sin 20 



Bn 2 



h - aex 4 a 2 (l + 2 cos 26 + cos 4(9), 



( 6l 2_l){a( 6l 2_l) + l! 



Also ^.' =: 2«e 1 2 cos 2 6>[(a + l)6 1 2 -a-(a+l)ae 1 2 sm2^. 



These formulae for co and a>' are suitable for the estimation 

 of the disturbance in the otherwise uniform course of the 

 rotatory dispersion due to the presence of absorption bands of 

 varying intensity. In order to illustrate the general nature 

 of the effects in a particular case, I have plotted on diagrams 



the values of the functions p(to-fl)i) and -^— r, against 



^( = n 2_^2) for the va i ues o-l (fig. 1), 1 (fig. 2), and 10 



(fig. 3) of the constant oc, which depends essentially on the 



