20 MR. CLIVE CUTHBERTOON AND MAUDE CUTHBERTSON ON THE 



TABLE XI. Dispersion of Mixtures of Ozone and Oxygen. 



Adding together all the values of the refractivities for each wave-length separately, 

 and dividing by the number of experiments, we obtain the refractivities for the 

 average mixture of ozone and oxygen, which are given as "means." Assuming 

 [MM^I"!!), = '000520 the percentage of ozone in this mixture is found as follows : 



52Qx+(lOO-z) 2717 = lOOx 287*03, whence x = 6'1764. 



To find the refractivities for the other seven wave-lengths we have only to use this 

 value and the refractivity for the corresponding wave-length of oxygen which we 

 take from our previous determinations, vide loc. cit. supra p. 2. Thus 



U-1JO.X6-1764 + 93-8236XU-1],, = [ Mx - 1] 



mixture . 



Tin- numbers obtained in this way are shown in the next line. 



It is at once noticeable that the dispersive power of ozone is much greater than 

 that of oxygen. And here again, as in the case of chlorine, we find that the curvature 

 of the experimental curve is greater than that calculated. Using M(J708 - 1 and M4800 - 1 



we obtain the formula M -l = 2 0414x 1Q! " whence we find , 



4221'3 x 10* 7 ?t*' /*6 



whereas the experimental value is 52000. 



As in the case of chlorine, the inference is that a second term is required. 



