Adsorption of Gases by Charcoal—Heat Effect.—The first part of this paper comprises a study of the heat effect on the adsorption of hydrogen and nitrogen by charcoal, and is a continuation of the work of Dr. Harvey B. Lemon1 in which air was used. The charcoal is heated for periods varying from one hour to twenty hours at temperatures from 400° C. to 1000° C., and at the same time the gases given off are pumped out with a mercury condensation pump. The activity of the charcoal is tested after each treatment by its adsorption of gas at liquid air temperature, and the results are shown by curves where logarithm of time in minutes, is plotted against logarithm of pressure in centimeters. The agreement with predictions from the hydrocarbon theory of adsorption are pointed out. That activation takes place by slow oxidation at room temperature is also shown.