Kinetic ProcedureAn accurately weighedamount of aspirin was dissolved in aqueous bufferor buffered cetomacrogol solution maintained a t37 * 0.1" in a thermostatically controlled waterbath. Duplicate samples were withdrawn a t zerotime and then at suitable time intervals. Onesample was assayed immediately for salicylic acidand the other for salicylic acid after completchydrolysis. The concentration of aspirin remaininga t each sampling time was calculated.