Dry powdered white lead is chiefly made for and used by grinders and mixers, who combine with it a variety of other cheaper materials--chalk, clay, sulphate of lime, and sulphate of baryta, but principal use is made of chalk and barytes. These are mixed with the white lead, and then the mixture is ground with oil and formed into paint, sold under various names according to quality: thus--guaranteed white lead, firsts, seconds, thirds, and fourths, the proportion of white lead diminishing, and that of the adulterant increasing, as we descend from the pure material. Guaranteed and best white lead is not pure, and does not mean pure white lead. Pure white lead can be purchased at some makers, but its price, if pure, can never fall below 19_l._ or 20_l._ per ton. To sophisticate white lead, and produce the various inferiors named, dry powdered white lead is needed as a starting point, and for this purpose principally arises the necessity for its production. If ground in oil the adulterants cannot be properly incorporated with it. Dry white lead is used for nothing else that could ever give rise to any great demand for it. We have already observed that the production of this dry and powdered white lead is the most dangerous proceeding connected with this industry. Grinding in oil is unattended with any important consequence to the health and comfort of those employed. A serious drawback to the “stack” production, the china-like incrustation to which reference has already been made, is that it requires crushing, grinding, washing, and drying, and a second course of dry grinding after it is dried--the most objectionable step in its preparation. Could the corrosion of the blue lead be effected in such a way as to prevent any discoloration of the material by the tan and wood--could the corrosion be so produced as to be easily separated from the buckle or grating on which it has formed--could this separation be so effected as to prevent the breaking up of the lead skeleton, and the presence of small pieces of metal in the detached crust of white lead, two principal reasons for washing and drying are removed. There is yet another consideration, that is, the presence of acetate of lead, always found in varying quantities in the incrustation produced, and remaining at the close of the operation and conversion. To remove this, careful washing, and after-stoving and drying must be accomplished. The amount of this salt present is found to differ with each operation, and in various portions of the same make. The washing out of the acetate is never perfect, and it involves a large amount of labour.