Very recent measurements of the electrical conductivity of solid systems AgX–CdX 2 (where X≡Cl, Br) that form large areas of solid solutions, have shown that maximum conductivity occurs for a concentration around 20mol% of the cadmium halide. Here, we suggest a quantitative explanation of this phenomenon based on a model that was recently suggested (J. Appl. Phys. 103, 083552, (2008)) for estimating the compressibility of multiphased mixed crystals. In addition, explicit conditions are obtained which predict when such a conductivity maximum is expected to occur.