The dielectric constant of water to high temperatures and pressures from the mean spherical model in the Wertheim solution

General expressions for the static dielectric constant of a fluid of hard cores with embedded point dipoles have been presented by Wertheim [1], on the basis of a Mean Spherical Model (MSM) treatment. Numerical results are derived for water from these expressions, with the additional inclusion of polarizability effects, using only the dipole moment strength, polarizability coefficient and diameter of water‐molecules. These results are compared with new experimental data for water extending to 800 K and 5 kbar. The calculated values compare satisfactorily with measured data at temperatures between 500 and 800 K, for all densities up to 1 g/cm3. In the lower temperature region, at high densities, the predicted values are systematically too high.