Pleochroism and Crystal Structure

Abstract

IN a very important paper (Phil. Mag., vol. 33, p. 521; 1917), Silberstein developed a theory of molecular refractivity based on the idea that the electric doublets induced by the field of the light wave in the atoms composing the molecule influence each other, the result of such atomic interaction largely depending on their relative distances and the geometric form of the molecule. One important consequence of Silberstein's theory, namely, that gaseous molecules should in general be optically anisotropic, is supported by observation, and has been worked out in detail by Ramanathan, Havelock, and others; it also forms the basis of W. L. Bragg's well-known and successful attempt to compute theoretically the birefringence of the solid carbonates and nitrates from their known crystal structure.