Abstract
We have measured the low frequency dielectric constant and its change with hydrostatic pressure of a variety of ionic solids of varying purity. Dielectric constants have been measured using a geometrical technique in association with a three-terminal transformer bridge system, a similar system also being used for the measurement of changes with pressure. It is shown that trace impurities do not give rise to greatly disproportionate effects. Some comparisons are made with and some conclusions are drawn from the Clausius-Mossotti equation, the Szigeti relations, and the model of Dick and Overhauser.