. . . . "Salts which can be added to increase the electrical conductivity of the electrolyte include soluble alkali metal, and alkaline earth metal sulfates, sulfides, chromates, phosphates and carbonates, such as sodium sulfate, potassium sulfate, lithium sulfate, calcium sulfate, sodium sulfide, potassium sulfide, lithium sulfide, sodium nitrate, calcium nitrate, potassium nitrate, lithium nitrate, sodiu" . . .