Chromic acid oxidation of teloschistin triacetate yields 4:5-diacetyl-7-O-methylemodic acid. The identity of this acid has been established by comparison with a sample obtained from physcion diacetate by oxidation and by its conversion into 7-O-methylemodic acid and its methyl ester on treatment with methyl alcoholic potash and methyl alcoholic sulphuric acid respectively. The location of the methoxyl group in teloschistin at position 7 has thus been rigidly established. The reduction of teloschistin to its anthranol and its regeneration from this compound are described.