IN the previous communication (Trans,, 1905, 87, 1412), it was shown that ellagic acid is formed when gallic acid dissolved in a mixture of acetic and sulphuric acids is oxidised by means of potassium persulphate. Experiments carried out in a similar way with protocatechuic, p-hydroxybenzoic, and m-hydroxybenzoic acids gave only minute traces of oxidation products insoluble in water, but, on the other hand, when concentrated sulphuric ...