SUMMARYA new method for rapid determination of moisture‐adsorption isotherms is a modification of the method suggested by Wilson and Fuwa in 1922. Air at a certain constant relative humidity is recirculated in a closed system through a tube loosely packed with a sample of solid particles, as a result of which the moisture in the sample equilibrates to the environmental relative humidity. This method is indirect but gives results in relatively short periods. A peristaltic pump, designed in this laboratory, circulated air through 12 independent closed systems. Thus, moisture‐adsorption isotherms in a wide range of relative humidities can be obtained in 24–36 hr. Moisture‐adsorption isotherms of flour obtained with this method agree very closely with those obtained with the constant‐relative‐humidity desiccator technique and with results reported by researchers who used a high‐vacuum technique in conjunction with a McBain‐Bakr sorption balance. The one limitation of this method is that it can be successfully applied only to solid particles whose physical state does not cause excessive resistance to flow of a
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