Vol. 6, 1920 
PHYSICS: H. H. SHELDON 
179 
charcoal was itself modified by heat alone or that the air was the agent 
causing these modifications. On this latter view a very complete theory, 
the hydrocarbon theory, has since been worked out by the Chemical 
Warfare Service. 
The theory as published was not, however, substantiated by the ap- 
pearance of any data in the journals, and accordingly certain experiments 
were begun here to satisfy ourselves regarding the conclusions arrived 
at. The apparatus and method were identical with those used by Dr. 
Lemon, and 25.7 gram of the same sample of charcoal. No. 16, was used. 
A similar sample to the one recorded was used as a check on all the work. 
The constant end pressure after heat treatments up to 600° C. both in 
the hydrogen curves, figure 1, and in the nitrogen curves, figure 2, show 
that the activation recorded by Dr. Lemon for these temperatures, must 
have been due to oxidation. At temperatures between 600 ° C. and 900 ° C. 
activation takes place, accounted for by assuming that inactive hydro- 
carbons, stabilized by adsorption, are, however, being boiled away at this 
