Alizarine

a substance contained In the madder root, and largely used in dyeing reds of various shades, Formerly madder root was largely employed as a dye-stuff, but the use a the root has been almost superseded by the employment of alizarine, prepared artificially from one of the constituents of coal-tar. {It forms yellowish-red prismatic crystals, nearly insoluble in cold, but di olved to a small extent by boiling water, and readily soluble fn alcohol and ether. It po e es exceedingly strong tinctorial powers.