Like the fusible anilid it dissolves in dilute alkali, but on acidifying the solution it does not immediately reappear. After standing for some time, however, it gradually separates in perfectly pure form. In this particular my observation differs from that of Gray,[27] who states that this anilid is decomposed by solution in alkali. [27] Inaug. Diss. J. H. Unis. 1895. A specimen that had been repeatedly precipitated gave the following results on analysis. I. 0.1607 gram gave 13.88 C.C.N. (standard). II. 0.2195 gram gave 0.1285 gram BaSO₄. III. 0.1357 gram gave 0.0807 gram BaSO₄. C[NH.C₆H₅]₂ / \ / O / / Cal. for C₆H₃——SO₂ \ NO₂ Found. I. II. III. N = 10.58 10.85 —— —— S = 8.06 —— 8.00 8.16 By this series of transformations it is possible to pass from one anilid to the other, the steps being: CO.NH.C₆H₅ C=N.C₆H₅ C[NH.C₆H₅]₂ / / \ / \ / / N.C₆H₅ / O / / / / / C₆H₃——SO₂NH.C₆H₅ ➡ C₆H₃——SO₂ ➡ C₆H₃——SO₂ \ \ \ NO₂ NO₂ NO₂ This is of special interest as affording a means of passing from a derivative of one of the chlorides, to a substance derived from the other, by steps that can be clearly followed. Conclusions. In the course of this investigation several facts have been established. 1. By the methods described, the symmetrical chloride of paranitroorthosulphobenzoic acid can be obtained in fine crystalline form, perfectly free from its isomer, with an average yield of forty percent. 2. By treatment of the chloride with benzene and aluminium chloride, only one chlorine atom can be replaced by a phenyl group. 3. The barium salt of paranitroorthobenzoyl benzenesulphonic acid, when perfectly pure, crystallizes constantly with seven molecules of water of crystallization. 4. With alcohols, the symmetrical chloride yields directly the acid etherial salt of paranitroorthosulphobenzoic acid, no evidence having been obtained of an intermediate chloro-etherial salt. The unsymmetrical chloride on the other hand yields the intermediate product. 5. With phenols, two series of derivatives are obtained. (1) With monohydroxy phenols, both etherial salts and sulphonphthaleïns are formed, the former predominating. (2) With polyhydroxy phenols no etherial salts were obtained, but compounds of the unsymmetrical type, usually containing more than two phenol residues. 6. With aniline an anil and an anilid of symmetrical constitution are formed. 7. With phosphorus oxychloride, the anilid, by loss of water, forms a dianil.