We use the equations of the Fuoss-Onsager theory, which are solved by a Green's function technique that yields explicit expressions in tems of the equilibrium pair correlation functions. The pair correlations needed to obtain these expressions are derived from either the hypernetted chain (HNC) or mean spherical (MSA) approximations. It is found that both yield rather good agreement with available experimental data for monovalent ions. The MSA has the advantage of yielding explicit expressions. In our treatment, the excluded volume of the ions is included in the corrections.