i8o PHYSICS: H. H. SHELDON Proc. N. A. S. 
temperature. Above this we find deactivation, due to the breaking up 
of hydrocarbons at this high temperature which form an inactive carbon 
deposit on the active base. 
In the case of U. S. Government 600 minute charcoal, no such deactiva- 
tion at this high temperature was observed, but in this charcoal the hydro- 
carbons are supposedly all removed. It offers no contradiction therefore. 
The outgassings were as indicated on the next page. 
1. 
8. 
+ 
-r 
-t 
-4- 
--4- 
10.1915. 
1. Julv 
10.1919. 
2. 
OOX. 
9.0 0.0 1.0 3.0 
LOG. tim 
Figure 3 shows how charcoal may be activated by slow oxidation at 
room temperature. Curve 1 was taken July 10, 1915, and the sample was 
then put away and left undisturbed until Oct. 10, 1919, when curve 2 was 
taken. 
The ease with which the charcoal could be deactivated for nitrogen 
compared to deactivation for hydrogen, suggested that a sample might 
be put into such a condition that it would adsorb hydrogen more readily 
than nitrogen. Results of this sort are shown in figure 4; curves 1 and 2 
are nitrogen and hydrogen, respectively, before treatment, and curves 
