(1) Tectoquinone, the volatile crystalline ingredient of the teak wood, which was isolated by R. Romanis in 1887, represents β-methyl-anthraquinone. (2) Tectoquinone, on oxidation, gives tectonic acid, which is identical with anthraquinone-β-carboxylic acid. (3) Tectoquinone, on reduction, gives a hydrocarbon ‘tectonene’, which, on examination, was proved to be β-methyl-anthracene. (4) Tectoquinone, on treatment with zinc and acetic anhydride, gives β-methyl-anthra-hydroquinone diacetate melting at 216–217°C., which is very easy to purify and thus may be used for the purpose of identifying tectoquinone. (5) β-Methyl-anthra-hydroquinone diacetate, on treatment with alcoholic potash and subsequent exposure to the air, regenerates tectoquinone of highest purity, melting at 176–177°C.