THE 



LONDON, EDINBURGH, akd DUBLIN 



PHILOSOPHICAL MAGAZINE 

 JOURNAL OP SCIENCE. 



[FIFTH SERIES.] 



MARCH 1882. 



XTIII. Electro-opAic Experiments on -carious Liquids. By 

 Johx Keee, LL.L>.,Free Church Training College, Glasgow*. 



THE following notes of experiments are intended as a 

 sequel to two of my former papers on Electro-optics, 

 which appeared in the Philosophical Magazine for August and 

 September 1879. In those papers I gave an account of me- 

 thods and results in connexion with twenty-seven liquid dielec- 

 trics; thirteen of them belonging to the class of fixed oils, and 

 all clearly active as nonconductors, with the one exception of 

 nitrobenzol. Shortly afterwards, Professor Piontgen repeated 

 and varied my experiments, and produced a very interesting 

 investigation on the subject ; and, in particular, he extended 

 the list of electro-optically active dielectrics by the important 

 addition of three bodies — water, sulphuric ether, and glyce- 

 rinet. To the list already published I have now to add more 

 than a hundred new liquids, with specification of their actions 

 as positive or negative, strong or weak, pure or impure. I 

 shall give first a condensed account of the experiments, and 

 then a summary of results (art. 29). 



Apparatus and Methods. 

 1. The small plate cell is the principal instrument used in 

 the present experiments. As I gave a fall description of this 



* Communicated "by the Author. 



t There is a good account of Professor Rontgen's paper in Mr. Gordon's 

 Treatise on Electricity. 

 Phil. Mag. S. 5. Vol. 13. No. 80. March 1882. 



