CHAPTER XII.

OF WHITE LEAD, VERDIGREASE, AND RED LEAD.

It will be proper to explain in what manner white leadis made, and also verdigrease, which we call seruca.The Rhodians place, in the bottoms of large vessels, alayer of twigs, over which they pour vinegar, and on thetwigs they lay masses of lead. The vessels are covered,to prevent evaporation; and when, after a certain time,they are opened, the masses are found changed into whitelead. In the same way they make verdigrease, which iscalled aeruca, by means of plates of copper. The whitelead is roasted in a furnace, and, by the action of thefire, becomes red lead. This invention was the result ofobservation in the case of an accidental fire ; and, by theprocess, a much better material is obtained than thatwhich is procured from mines.