IN connexion with the recent development of the theory of activation of adsorption processes by H. S. Taylor (J.A.C.S., 53, 578 ; 1931), it may be interesting to note that a ‘Norite’ charcoal, which adsorbed practically no hydrogen at room temperatures, adsorbs hydrogen at increasing rates as the temperature is raised. Thus, when 1.17 c.c. hydrogen were admitted to the charcoal at 395° C., the pressure fell from 0.514 cm. to 0.076 cm. after 9 hours, about 1 c.c. of gas being adsorbed. At 340° C., with an admission of 1.19 c.c, the pressure only fell from 0.572 cm. to 0.251 cm. in a similar period, showing a much smaller and slower adsorption of hydrogen than at 395° C. At temperatures below 200° C. the rate of adsorption is too slow to be measurable.