THE condensation of osalic acid and resorcinol has been studied by various chemists, interaction being induced either at high temperatures or by the use of a condensing agent, Apparently, the first to study the reaction was A. von Baeyer (Bey., 1871,4,662), who stated that, on heating with sulphuric acid, a yellow substance was obtained which does not exhibit fluorescence in solution, and is apparently similar to euxanthone, with the exception that i t cannot be sublimed. Von Baeyer,

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... s, thought i t probable that the substance was a mixture in which euxanthone was present, The next work on tEie subject was that of Claw and Andreae (Ber., 1877, 10, 1305), who heated a mixture of resorcinol (1 mol.) with dehydrated oxalic acid (2 mols.) in sealed tubes for 2 to 3 hours at 2 0 0 O ; the product mas mixed with alcohol and poured into water, a substance being thrown down which was purified by soliltion in alcohol and reprecipitation by water. When dissolved in alkalis, i t shows a moss-green fluorescence, which is always exhibited, no matter how many times the substance has been taken up by alcohol. The