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XV. On Double Refraction, produced by Electrical Influence, in 

 Glass and Bisulphide of Carbon. By H. Brongersma*. 



[Plate IV. fig. 5 «-/<.] 



I. 



THE phenomena first observed by Kerrf, and described in 

 his papers entitled " A new Eelation between Electricity 

 and Light/' I have submitted to a reexamination. The im- 

 portance of the subject, and the failure of the attempts of 

 various physicists to repeat Kerr's experiments, so far as these 

 relate to solid bodies, have induced me to undertake this inves- 

 tigation. 



The willing readiness of the Directors of the " Teyler's 

 Stichting " at Harlem to place an apartment and the necessary 

 instruments at my disposal has made it possible for me to 

 accomplish this labour, which, as I hope, has resulted in pro- 

 ving that the doubt of the correctness of Kerr's results was 

 not well founded. 



If I mistake not, Gordon was the first who repeated Kerr's 

 experiments, and, indeed, in spite of all his carefulness, with 

 a negative result J. In a work published subsecmently§, he 

 returns to the subject. After describing the phenomena which 

 he had once observed when the glass was perforated by the 

 spark, he says : — " A fresh glass plate was at once drilled, in 

 hopes of repeating the experiment in the lecture next day ; 

 but, owing to sparks springing round, we did not succeed in 

 perforating the glass, and therefore saw only the faint return 

 of light described by Dr. Kerr." The words which I have 

 italicized make it in some degree doubtful if the phenomenon 

 observed by Gordon must not be attributed to accidental 

 causes. I have found that a piece of ordinary plate glass is 

 rendered doubly refracting only by the electric spark passing 

 in proximity to it, or when a heated wire is brought near the 

 plate. 



Mackenzie || also did not succeed in obtaining Kerr's pheno- 

 menon. He thought it was produced by heat only. 



An investigation by RontgenH likewise gave negative 

 results. He also believes that some accidental influences were 

 at work in those experiments. 



* Translated from Wiedemann's Annalen, 1882, no. 6, pp. 222-233. 

 t Phil. Mag. [4] vol. 1. p. 337 (1875). 

 X Phil. Mag. [5] vol. ii. p. 203 (1870). 



§ A Physical Treatise on Electricity and Magnetism, by J. E. H. Gor- 

 don, vol. ii. p. 247. 



|| Wiedemann's Annalen, ii. p. 350 (1877). U Ibid, x. p. 77 (1880). 



