246 



Mr. S. S. Richardson on Magnetic Rotary 



Water. 



Pure conductivity water only was used and the rotation 

 was measured ^ith the solenoid. For the ultraviolet the 

 values were deduced from the photographs by the second 

 method described above, and these were converted into 

 absolute rotations by the use of Rodger and Watson's value 

 for the D line. The refractive indices n given in the table 

 are those of Gifford * corrected for the temperature difference 

 20°-15° 0. The change of magnetic potential on reversal 

 was 42,238 cm.-gauss, giving a doubled rotation of over 9° 

 for X=='58d3 and nearly 43° for the line '"3034. 



For convenience of reference in this and the following- 

 tables the observations for different wave-lengths are distin- 

 guished by the letters a, b, c, etc. 



Obs. 

 a 



AXHK 



dxlO 6 . 



W 20- 



0X10" (obs.). 



<p X 10" (calc). 



A<f>. 



•5893 (Na) 



3-808 



1-3330 



1-763 



1-764 



+ 1 



b 



•4958 (Fe) 



5-529 



1-3366 



1-816 



1-816 







c 



•4678 (Ccl) 



6-276 



1-3381 



1-838 



1-839 



+ 1 



d 



•4341 (H) 



7-431 



1-3403 



1-877 



1-875 



-2 



e 



•3962 (Al) 



9-159 



1-3435 



1-931 



1-929 



—2 



/ 



•3611 (Cd) 



11-389 



1-3475 



2-002 



2001 



-1 



9 



•3303 (Zm 



14-218 



1-3523 



2-098 



2-091 



— 7 



h 



•3034 (Sn) 



17-620 



1-3580 



2-203 



2-206 



+3 



The values of X : calculated from equation (9) are 



ab = -109 



bd = -111 ad = -110 



df= '112 ^ = '114 



fh = '114. 



The values of X chosen for the calculation must be as widely 

 separated as possible, as the effect of a small experimental 

 error becomes greatly magnified when \ : is calculated from 

 two points on the dispersion curve which lie too close 

 together. 



Lowryt has determined the dispersion ratio of the magnetic 

 rotations for the two mercury lines *5461 and *4359 for 

 water and a number of aliphatic compounds, using a very 

 powerful magnet. In the case of water, 



|« ==1-645. 



0(5461) 



* Proc. Roy. Soc. Ser. A, lxxviii. 

 f Jour. Chera. Soc, Jan. 1914. 



