Barium carbonate as a flux, a matting and crystallizing agent and combines with certain colouring oxides to produce unique colours not easily attainable by other means. Its use is somewhat controversial since some claim that it can leach from glazes into food and drink. To provide a safe means of use, BaO is often used in fritted form. In the brick, tile, earthenware and pottery industries barium carbonate is added to clays to precipitate soluble salts (calcium sulfate and magnesium sulfate) that cause efflorescence. Barium carbonate Barium carbonate (BaCO), also known as witherite, is a chemical compound used in rat poison, bricks,
Brass percentages of nickel, lead and iron. During the later part of first millennium BC the use of brass spread across a wide geographical area from Britain and Spain in the west to Iran, and India in the east. This seems to have been encouraged by exports and influence from the Middle East and eastern Mediterranean where deliberate production of brass from metallic copper and zinc ores had been introduced. The 4th century BC writer Theopompus, quoted by Strabo, describes how heating earth from Andeira in Turkey produced "droplets of false silver", probably metallic zinc, which could be used to turn