The principal results relating to s.fluoresceÏn which have been reached in this work may be briefly summarized as follows. Orthosulphobenzoic acid acts on resorcin at a temperature of about 180° giving off water and forming a substance analogous to fluoresceÏn but having the CO group replaced by SO₂. This substance sulphonfluoresceÏn crystallizes from water in light yellow monoclinic crystals having the composition C₁₉H₁₂O₆S + 2H₂O. It is very soluble in alcohol and water and with difficulty in ether. It does not melt under 250° but above 300° melts with decomposition. It shows in alkaline solution a clear green fluorescence. It acts as an acid, decomposing carbonates and forming salts, the Ba salt having the composition C₁₉H₁₃O₇SBa. It forms an acetyl compound when boiled with acetic anhydride. It forms substitution products with Br, probably the dibrom-product most easily. It forms a compound with H₂SO₄, probably a substitution product, whose composition was not determined. It is reduced by zinc dust and KOH to a colorless substance analogous to fluoresceÏn.

Finally in terms of the prevalent theory the substance itself may be represented thus—