Thusfive hundred and sixty-three pounds of a seventeen-per-ccnt. grade of lithopone will be precipitated, from which the soda liquor may be filtered and then washed out. Fifty six pounds of sodium hydrosulfid may then be recovered from the solution, if no further treatment thereof is contemplated, by any suitable evaporating process. By employing sodium sulfate and suitably altering the reaction I have also produced lithopone and sogo dium sulfid. The products of these reactions will be found to be of unusual purity and require no subsequent treatment for placing them upon the market.