Abstract
The derivation of formulae to express the isotropic, as well as the anisotropic, part of the Rayleigh factor of pure liquids in the characteristics of the polarizability tensor of the free molecules is reviewed. The effect of the internal electric field on each of the two types of scattering is indicated. The formulae obtained have been applied to experimental results. For anisotropic scattering, additional effects, such as orientation correlation of the molecules, or anisotropy of the internal field, may be taken into account.