The influence of molecular form and anisotropy on the refractivity and dielectric behaviour of liquids

Abstract

Recent investigations on the diffraction of X-rays by liquids throw considerable light on their molecular structure. One conspicuous result that emerges out of these investigations is that when the molecules are asymmetric in shape, as in general they are, their average distribution around any given molecule in the liquid is far from being spherically symmetrical with respect to it. When the medium is under the influence of an electric field, the well-known Lorentz polarisation field acting on any given molecule, arising from the polarisation of the surrounding ones, will then naturally vary width the orientation of the exciting field with respect to the molecule. Independent evidence for such an “anisotropy” of the polarisation field is forthcoming when we correlate the measurements on electric double-refraction and on light-scattering in the liquid state with the corresponding values for the same substance in the state of vapour, The general mathematical theory of refraction by dense media takes into account this anisotropy of the polarisation field, has been developed in a recent paper. It is proposed in the present communication to discuss the theory outlined in that paper in its relation to actual experimental results, confining ourselves mainly to one typical case, viz., benzene, for which accurate measurements are available for the various physical quantities appearing in the expressions.