248 Mr. S. S. Richardson on Magnetic Rotary 



Benzene. 



In the case of benzene and the liquids following, the 

 electromagnet was employed in order to reduce absorption 

 by the use of a short column of liquid. The values of n are 

 deduced from the observations of Simon. The values of 8 

 are here all obtained from the photographs, the analyser 

 settings being varied from each line until equality of illumi- 

 nation was obtained. £ = 20° C. The absolute rotations 

 are obtained by using Perkin's water-ratio for the D line 

 <2-3053). 



Obs. 



XX 10*. 



3X10 6 . 



M 2t . 



0X1O 14 . 



Ref.... 



a 



b 



c 



d 



e 



•5893 

 •4529 

 •4046 

 •3631 

 •3306 

 •3100 



8-778 

 16-49 

 2221 

 30-32 

 40-95 

 5151 



1-5004 

 1-5187 

 1-5311 

 1-5475 

 1-5670 

 1-5850 



4-574 

 5-137 

 5-567 

 6-186 

 7-014 

 7-846 



ac = -1681 

 bd = -1716 

 ce = -1747 



Calculating the values of X x from equation (9) we find 

 progressive values, namely : — 



ah = -1662 



be = -1694 



cd = -1734 



de = '1762. 



As the amount of increase is here considerable, at least 

 two free-periods probably widely separated may be expected. 

 Using equation (10) to obtain a closer approximation to the 

 longer period, we obtain : — 



from bee, X 1= = -19071 



ace, \ = -1903 I Mean - '1902/i. \^ ='03618. 

 bde, X 1 = -1897J 



h Y = 2-468, k 2 = 1-498. 



Thus 10** = 2-468 (^^f + 1-498. 



The differences between the values of <j> calculated from 

 this and the observed values are given below. 



