Abstract
Previous theories advanced to account for the differences between the moments of polar molecules, as measured in dilute solution (in non-polar solvents) and from gas measurements, are discussed on the basis of an internal field function ξ, determining the field inside an ellipsoidal obstacle in a polarized uniform medium. Contours of ξ as a function of the axial ratios of the ellipsoid have been calculated. Onsager's theory of the static dielectric constant is extended to account for the solvent effect in ellipsoidal solute molecules of uniform polarizability, in which the dipole is parallel to one of the axes of the ellipsoid; the new equation thus obtained gives results in better agreement with experimental data than previous theoretical treatments.
The rule that the sign of the solvent effect of a substance should be opposite to that of its Kerr constant is shown not to be of general applicability.