a liz a rio acid

[PHTHALIC-ACID.] al-iz-ar-in, s. [From alizari, the name given to madder in the Levant.] Chem.: C14H8O4=C12H6(CO.OH)2. The chief colouring matter of madder ( Rubia tinct or i a ), It crystallises in red prisms, slightly soluble in water or alcohol, but di olving in concentrated sulphuric acid, also in alkaline liquids. It is a feeble dibasic acid. Heated with zinc dust, it is converted into anthracene. Nitric acid oxidises it into oxalic and phthalic acids. Alizarin has been produced artificially by oxidising anthracene to anthraquinone, converting the latter into dibromanthraqui 151 none, and heating this with caustic potash, the two atoms of Br are replaced by (OH)2 al-iz-ite, s. [ALIPITE.]