We present a novel microfield approach for studying the dependence of theorientational polarization of the water in aqueous electrolyte solutions uponthe salt concentration and temperature. The model takes into account theorientation of the solvent dipoles due to the electric field created by ions,and the effect of thermal fluctuations. The model predicts a dielectricfunctional dependence of the form $\varepsilon(c)=\varepsilon_w-\beta L(3\alphac/\beta),\quad\beta=\varepsilon_w-\varepsilon_{\rm ms}$, where $L$ is theLangevin function, $c$ is the salt concentration, $\varepsilon_w$ is thedielectric of pure water, $\varepsilon_{\rm ms}$ is the dielectric of theelectrolyte solution at the molten salt limit, and $\alpha$ is the total excesspolarization of the ions. The functional form gives a remarkably accuratedescription of the dielectric constant for a variety of salts and a wide rangeof concentrations.
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