On evaporating the aqueous extract from the original melt almost to dryness on the water-bath, there was a deposit on the sides of thedish of scales possessing a beautiful bronze-green metallic lustre They formed a deep purple solution in alkalis, or magenta, if the solution was very dilute, and orange-yellow in acids. On acidifying the alkaline extract with hydrochloric acid, this same substance was precipitated as a brownish flocculent precipitate. It was, however, found to be impossible to obtain this substance in pure condition. The amount formed in the reaction is small, and its properties were such as to render work with it very difficult. The method of precipitation is not satisfactory because, owing to the fact that the substance is soluble in acid solutions to an unusual extent for substances of this class, the solution had to be concentrated to such a degree as to render the precipitated substance very impure from acids and alkali salts. These could not be removed by washing, obviously, without again dissolving the substance. From its properties however, and its color reactions, there can be little doubt that the substance is a sulphonphthaleïn, and that it is always formed in considerable quantities in the reaction of phenol upon the symmetrical chloride. It was noticed that the aqueous extract of the mass left after fusion was almost always decidedly acid in reaction, and it was thought that this might be due to the formation of an acid etherial salt, whose formation would be expressed by the equations: COCl COOC₆H₅ / / C₆H₃——SO₂Cl + C₆H₅OH = C₆H₃——SO₂Cl + HCl. \ \ NO₂ NO₂ COOC₆H₅ COOC₆H₅ / / C₆H₃——SO₂Cl + H₂O = C₆H₃——SO₂OH + HCl. \ \ NO₂ NO₂ Accordingly, the solution was saturated with barium carbonate, the excess of carbonate removed by filtration, the filtrate concentrated, and allowed to cool. Crystals in the form of pearly scales separated, which upon analysis proved to be the neutral barium salt of paranitroorthosulphobenzoic acid. 0.2291 gram anhydrous salt gave 0.1386 gram BaSO₄. COO / \ / Ba / / Cal. for C₆H₃——SO₂O \ NO₂ Found Ba = 35.85 35.57 This would seen to indicate that the reaction is an incomplete one even in the presence of excess of phenol. No indications of the formation of an acid etherial salt was observed. 2. The Action of Orthocresol upon the Symmetrical Chloride of Paranitroorthosulphobenzoic Acid.