During the reaction, which is complete at 125°, the mixture becomes almost perfectly solid, and when cool, it is quite brittle. It was reduced to a reddish powder in a mortar and dissolved in sodium hydroxide, there being no insoluble residue. By the addition of hydrochloric acid, the sulphonfluoresceïn was thrown down as a chocolate-brown precipitate, which was filtered off, washed to neutral reaction on a filter, and dried on paper. In this condition it is a light chocolate-brown powder. In dilute alkaline solution it possesses a slight fluorescence being pink by transmitted and yellow be reflected light, suggesting eosin in a general way. It is interesting to note that the sulphonfluoresceïn of orthosulphobenzoic acid possesses a fluorescence that can hardly be distinguished from ordinary fluoresceïn and that the introduction of a nitro group into the acid residue produces much of the same effect as do the four bromine atoms in eosin. In acid solution the color is reddish-orange. Analysis of the compound, prepared as above described, gave the following results. I. 0.1745 gram gave 0.3339 gram of CO₂ and 0.059 gram H₂O. II. 0.1467 gram gave 0.2820 gram CO₂ and 0.0432 gram H₂O. III. 0.1732 gram gave 0.3345 gram CO₂ and 0.0571 gram H₂O. IV. 0.2000 gram gave 0.1104 gram BaSO₄. V. 0.1505 gram gave 0.0820 gram BaSO₄. OH ] / ] C[C₆H₃ ] / \ \ ] / O OH ]2 / / Cal. for C₆H₃——SO₂ \ NO₂ Found I II III IV V C = 52.66 52.18 52.42 52.67 —— —— H = 3.46 3.76 3.27 3.66 —— —— S = 7.39 —— —— —— 7.57 7.48 An effort to obtain the anhydride was unsuccessful. Some loss of weight was observed, but the compound underwent decomposition before this loss amounted to much. 6. The Action of Pyrogallol upon the Symmetrical Chloride of Paranitroorthosulphobenzoic Acid. The product of this action dissolves readily in dilute sodium hydroxide without residue, producing a very deep purple-black color when concentrated, passing to grayish-violet as the solution is diluted. On adding hydrochloric acid, precipitation occurs, as in most of these reactions. On attempting to filter off this precipitate, it forms a sticky, black mass on the filter with which little can be done. It is best to evaporate to dryness before filtration and powder the residue. This powder can then be washed fairly clean from alkali salts and acid. Nothing to suggest the formation of an etherial salt was observed.