Mucic Acid, C6H1008 or Hooc. (Choh) 4. Cooh, is obtained by the oxidation of milk, sugar, dulcite, galactose, quercite and most varieties of gum by nitric acid. It forms a crystalline powder which melts at 213° C. It is insoluble in alcohol, and nearly insoluble in cold water. When heated with pyridine to 140° C., it is converted into allomucic acid. When digested with fuming hydrochloric acid for some time it is converted into ad furfurane dicarboxylic acid (see Furfurane); while on heating with barium sulphide it is transformed into a - thiophene carboxylic acid (see Thiophene). The ammonium salt yields on dry distillation carbon dioxide, ammonia, pyrrol and other substances. The acid when fused with caustic alkalies yields oxalic acid.