I will now describe some typical methods of practicing my invention, whereby lithopone of any desired grade may be produced. One of the known grades of lithopone as prepared and mixed for the trade contains sev- 6o enteen per cent. of zinc sullid. To produce this grade and a by-product of hydrosulfid of sodium, for example, I proceed as follows: The usual precautions, it will be understood, mustbe taken in preparing or for insuring the purity of the several ingredients used; but these preliminaries do not require description here. Separate aqueous solutions of the following ingredients in the proportions named are prepared: zinc sulfate, one x hundred and sixty-one pounds; barium sulfid, three hundred and thirty-eight pounds, and sodium bisulfate one hundred and twenty pounds. These ingredients, it will be recognized, are readily soluble in water. The separate solutions are then mixed and the following chemical reaction at once takes place:
