Calculated for C_{19}H_{10}Br_{2}O_{6}S = 30·42% Br. These results, though not conclusive, indicate that under the given conditions it is the di-bromsulphonfluoresceïn which is formed. Whether this is due to the presence in the compound of the SO_{2} group or simply to the greater insolubility of the di-than of the tetra-brom product cannot be definitely stated. When the original acetic acid mother liquor was evaporated to dryness, a red non-crystalline substance remained which more closely resembled rosin than the crystals. The concentrated alkaline solution had a deep red color without fluorescence and acted as a red dye stuff. The dilute alkaline solution showed the characteristic delicate pink of rosin. Action of H_{2}SO_{4} on S.fluoresceïn. A test tube in which S.fluoresceïn was being made just at the end of the reaction broke and allowed the contents to run out into the sulphuric acid bath, which had a temperature of 175°. On standing several days the solution deposited a heavy precipitate which was separated by filtering through glass wool. When dry it formed a light yellow powder extremely soluble in water, alcohol and ether. The alkaline solution had an intense green fluorescence with delicate shades of pink by transmitted light. On account of its great solubility it was impossible to purify it by crystallization, hence the Ba salt was made. The substance decomposed BaCO_{3} with great ease forming an easily soluble salt. When it was attempted to evaporate the solution of this salt to crystallization the latter came out in a hard insoluble granular form and on continuous boiling of the solution turned brown. To avoid this undesirable form it was converted into the Ca. salt by treatment with H_{2}SO_{4} and then CaCO_{3}. This also formed a hard granular insoluble mass on boiling but did not change in color. As there was no guarantee as to its purity and only a small quantity was obtained it was not analyzed. Action of HCl on S.fluoresceïn. Hydrochloric acid does not dissolve S.fluoresceïn but converts it into a light yellow granular powder. When recrystallized from water in which it is quite easily soluble it melts partially at 130° apparently with some decomposition. This compound was not further studied. Reduction of S.fluoresceïn. When treated with zinc dust in a strong alkaline solution sulphonfluoresceïn is reduced to a colorless substance probably analogous to fluoresceïn which is formed in the same manner. On account of its great solubility it could not be obtained in the free state. It is quickly oxidized to s.fluoresceïn by oxidizing agents as KMnO_{4} and HNO_{3} and passes back spontaneously on standing in the air. The latter action is however much slower than in case of fluoresceïn. Conclusion.