Magnetic double refraction

Abstract

The action of a strong magnetic field in causing a liquid to become birefringent for light rays transverse to the field was first observed by Cotton and Mouton in nitrobenzene, and was later detected and measured by the same authors in many other carbon compounds of the aromatic series and in some inorganic liquids (Annales de Physique, 28, 209-243 1913). In a recent paper (C. V. Raman and K. S. Krishnan,Proc. Roy. Soc., A, Jan. 1927) it has been shown that the large value of the Cotton-Mouton constant in aromatic compounds indicates that the benzene ring, which is known from observations on light-scattering to be optically anisotropic, has also a very pronounced magnetic anisotropy. Observations on light-scattering in carbon compounds of the aliphatic series indicate that the molecules of these substances are optically anisotropic to an extent which, though smaller than in the aromatic series, is yet very marked (K. S. Krishnan, Phil. May., 50, 697; 1925). It accordingly seemed very probable that the compounds of the aliphatic series should also exhibit magnetic anisotropy and give a measurable double-refraction in strong magnetic fields.