Chapter II molecular and ionic interaction in dielectrics

No fundamental changes in dielectric theory have occurred during the past year although certain advances in detail and generalization have been made. An investigation of the influence of molecular shape (1) on the dielectric constant of polar liquids has led to a modification of Onsager´s equation. Dipole moment values deduced from the new equation agree rather better with the gas values. The remaining discrepancy of some 5–15% is thought to reflect the limit of accuracy possible with a purely electrostatic theory. A somewhat similar problem has been treated by Frood and Dekkar (2) who have extended the simple Onsager theory of the dielectric constant of polar materials to the case in which the dipole is not a mathematical point dipole at the center of the cavity. This involves, in particular, a somewhat more detailed consideration of the reaction field but does not lead to any change in the formula for the dielectric constant.