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This paper reports, for solutions of 0.001 M uranyl sulfate and 0.005 M oxalic acid, a 10-degree temperature coefficient, up to 85°C (using a base temperature of 25°) of 1.02±0.01 at 254 m/x. Measurements in more dilute solutions show a decrease to approximately unity at 0.00025 M uranyl sulfate—0.00125 M oxalic acid, with indication that it may become less than unity on further dilution. Quantum yields measured (using uranyl oxalate as standard), by students under a National Science Foundation "pilot" undergraduate participation project, on actinometers at 254 rn.fi, were for (1) malachite green leucocyanide, 0.9; (2) monochloroacetic acid, 0.3; and (3) potassium ferrioxalate, 1.24 moles per einstein.