M. Eppley,1studying the relation between the degree of saturation and the emf, and the temperature coefficient of emf on acid unsaturated standard cells acidified to 0.012 mol per litre of sulphuric acid, has concluded that the acid unsaturated cells with cadmium sulphate concentration of 42.93 percent have negligible temperature coefficients between 15° and 35°C, and that the solutions of these cells might have been saturated at about 4°C.The present authors2measured, in the first place, the solubility of cadmium sulphate into dilute sulphuric acid at different concentrations, and based on the obtained results, with electrolytes of various concentrations from dilute to nearly saturated solutions of cadmium sulphate. They attempted to find out the optimum concentration of cadmium sulphate and acidity of electrolyte, estimated from every point of view, and concluded that cells of concentration of cadmium sulphate 43.0 percent and of acidity 0.05N are most suitable.