It does not melt at 250° but if held at a lower temperature for a long time becomes red undergoing some decomposition. If quickly heated somewhat above 300° it melts to a deep red liquid and then solidifies. If the mass is treated with water it partly dissolves leaving a dark brown flocculent precipitate which dissolves on the addition of an alkali, the solution having an intense fluorescence, nearly if not quite equaling that of fluoresceïn. This change produced by heating was not further studied. The crystals are very thin blades, apparently monoclinic, showing the clinopinacoid αΡὰ and a very narrow prism αΡ and clinodome Ρὰ. The angle β = 75° and the extinction angle against the ϲ axis = 20°. The axial ratio could not be accurately determined. Salts of sulphonfluoresceïn. The influence of the SO_{2} group is shown by the fact that the substance acts as an acid decomposing carbonates and forming salts which is not the case with fluoresceïn. Barium salt. The substance was boiled with an excess of carefully purified BaCO_{3} for two hours. The filtrate from the BaCO_{3} evaporated to a small volume deposited yellow crystals resembling the original substance but in shorter and thicker prisms. These were twice recrystallized and had then a light straw yellow color. A determination of the Ba gave the following results. The salt was dried in the air. [Transcriber’s Note: The following table was crossed out on the original. A note on the previous page beside the table was: All these calculations are wrong. J.R.] I ·1078 gr salt gave ·0304 gr BaSO_{4} = 15·73% Ba. II ·1641 ” ” ” ·0457 ” ” = 15·53” ” III ·2425 ” ” ” ·0680 ” ” = 15·65” ” IV ·2860 ” ” ” ·0798 ” ” = 15·54” ” V ·1843 ” ” ” ·0498 ” ” = 15·08” ” VI ·2620 ” ” ” ·0708 ” ” = 15·08” ” VII ·3230 ” ” ” ·0906 ” ” = 15·65” ” VIII ·2875 ” ” ” ·0807 ” ” = 15·66” ” Calculated for C_{19}H_{13}O_{7}SBa = 15·10% Ba. In the above determinations the salt analysed was taken from specimens made at three different times and purified in slightly different ways, Nos 1, 2, & 3 being washed with absolute alcohol. Nos V and V were made by precipitating the Ba with H_{2}SO_{4} from a solution of the salt. The water was determined by heating at 110° till constant weight was reached. Part only of the weight lost was regained on standing in the air. ·3943 gr salt lost at 110° ·0286 gr = 7.25% Water calculated for C_{19}H_{13}O_{7}SBa+2H_{2}O = 7.35%