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XL VI. On Double-Refraction in Moving Viscous Liquids. By 

 Ladislas Natanson, Professor of Natural Philosophy 

 at the University of Cracow*. 



ACCIDENTAL double-refraction is produced in a tran- 

 sparent substance by distorting the latter, the double- 

 refraction disappearing as soon as the distorting cause ceases 

 to act. Observed for well-nigh a century in the case of 

 solids, it was discovered, in 1873, by E. Mach t in plastic 

 bodies, and — almost simultaneously — by Clerk-Maxwell % in 

 the case of certain highly viscous liquids. In 1881 A. 

 Kundt§ attacked the problem of double-refraction in liquids, 

 and considerably advanced the subject. This physicist sub- 

 jected the liquids under study to constantly re-applied and 

 hence permanent distortions ; in this way he was able to 

 establish the phenomenon of double-refraction (also per- 

 manent) for a considerable number of liquids. In the same 

 paper Kundt, starting from certain hydrodynamical theorems 

 established by Sir G. G. Stokes ||, has attempted to develop 

 the theory of the experimental method adopted by him. 

 The merit of having carried out the first quantitative 

 measurements in connexion with accidental double-refraction 

 in liquids rests with G. de Metz^f, who in his experi- 

 ments made use of the principle employed by Kundt. The same 

 method has been used by K. Umlaut**, J. E. A] my ft* and 

 Bruce V. Hill i J, and has enabled them to obtain relatively 

 accurate results, in spite of the many difficulties inherent in 

 this kind of research. Finally, in a recent paper by R. 

 Reiger§§ will be found an account of some very interesting 

 experiments on accidental double-refraction in certain plastic 

 substances ; the method adopted by Reiger approaches more 

 nearly that which enabled Mach and Maxwell to demonstrate 

 the reality of the phenomenon in question. 



In the present communication we propose to discuss the 

 theory of accidental double-refraction in liquids ; we shall, 



* Translated from the Bulletin de VAcademie des Sciences de Cracovie, 

 March 1901. Communicated by the Author. 



t Optisch-akustische Versuche, Prag 1873. 



t Proceedings of the Royal Society, No. 148 (1873) ; Scientific Papers, 

 vol. ii. p. 379 (1890). 



§ Wiedemann's Annalen, Bd. xiii. p. 110 (1881). 



|| Transactions of the Cambridge Philosophical Society, vol. viii. 

 184o ; Mathematical and Physical Papers, vol. i. p. 102 (1880). 



T\ Wiedemann's Annalen, Bd. xxxv. p. 497 (1888). 



** Ibid. Bd. xlv.p.304(1892). 



tt Philosophical Magazine (o) vol. xliv. p. 499 (1897). 



XX Ibid. vol. xlviii. p. 485 (1899). 



§§ Fhrjsikalische Zeitschrift, Jahrg. ii. no. 14, p. 213 (1901). 



Phil. Mag. S. 6. Vol. 2. No. 11. Nov. 1901. 2 I 



