Red Lead
When metallic lead is exposed at a red heat to a current of air, the lead rapidly combines with oxygen, and the oxide so produced fuses. It forms, on cooling, crystalline masses of a greenish-yellow color; this constitutes the litharge of commerce. Red lead is produced when the lead is oxidized so that the oxide formed shall not be fused, and when the metal is all converted into the yellow powder, increasing the heat to incipient redness. Oxygen continues to be absorbed until one third of the metal is converted into peroxide; this is the pure red lead. See LEAD; LITHARGE.