Litharge, or Lead Monoxide, a yellow or buff-colored compound of lead and oxygen. It is also known as massicot. Litharge is used as a paint pigment, as a drying agent in oils and varnishes, and in the manufacture of flint glass, lenses, red lead, insecticides, and match heads. The compound is also used to glaze pottery and, in assaying, as a flux, a substance that combines with impurities.

Chemical formula: PbO. Melting point: 1,630 F. (888 C).