178 
PHYSICS: H. H. SHELDON 
Proc. N. a. S. 
1 Contribution from the Ballistic Institute, Clark University, No. 7. 
2 Webster, A. G., "On A Means of Producing a Constant Angular Velocity," Amer. 
Jour. Sci., 3, May, 1897 (383-386). 
3 Webster, A. G., "An Experimental Determination of the Period of Electrical Oscil- 
lations," Physic. Rev., 6, 1898 (297-314) ; Hubbard, J. C, "An Experimental Determina- 
tion of the Period of Electrical Oscillations," Physic. Rev., 2, 1, 1913 (247-249). 
^ Webster, A. G., Proc. Nat. Acad. Sci., 5, May 1919 (163-166). 
^ Webster, A. G. Thompson, L. T. E- "A New Instrument for Measuring Pressures 
in a Gun," Proc. Nat. Acad. Sci., 5, p. 258-263. 
6 Webster, A. G., "Some Considerations on the Ballistics of a Gun of Seventy-five- 
Mile Range," Proc. Amer. Phil. Soc, 58, p. 373-381. (Note by A. G. W. It should 
be stated that the linear law is not now considered exact. M. Lugot, of the Com- 
mission de Gavre, informed the writer that the curves should rise a little above the 
straight lines, but the error is small.) 
7 Experiments to measure the compression are now in progress. — A. G. W. 
CHARCOAL ACTIVATION 
By H. H. Sheldon 
RyErson Physical Laboratory, University of Chicago 
Communicated by R. A. Millikan, February 20, 1920 
The results obtained by Dr. Harvey B. Lemon on the variations due 
to heat treatment in the adsorption of gases by charcoal/ although pub- 
lished but recently, were obtained some time ago. There seemed two 
possible explanations of these results— either that the structure of the 
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LOG. TIME 
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