tion of the precipitate, the mass is filter pressed, dried, muflled and processed in the on the market, in that the {covering capacity of the pigment is greatly increased, as well The titanium oxide is peptized or held in as its fastness to light, and ease of working in oils. It is also superior to the so called double strength lithopone made by doubling the zinc sulphide conent, in that it is very neutral to acid vehicles. It is also far superior to other titanium compounds on the market, inasmuch as greater opacities are obtained with a relatively small amount of titanium oxide, than has heretofore been obtained with far greater proportions of titanium oxide, thereby effecting a considerable economy over that of other similar products containing'titanium oxide.

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: