395 



TABLES 603-505. 

 RADIOACTIVITY. 



TABLE 503. Stopping Powers of Various Substances for a Rays. 



s, the stopping power of a substance for the a rays is approximately proportional to the square 



root of the atomic weight, w. 



Bragg, Philosophical Magazine, n, p. 617, 1906. 



TABLE 504,- Absorption of Rays by Various Substances. 



/*, the coefficient of absorption for ft rays is approximately proportional to the density, D. 



Table 506 for n for Al. 



See 



For the above data the rays from Uranium were used. 

 Crowther, Philosophical Magazine, 12, p. 379, 1906. 



TABLE 506^- Absorption of 7 Rays by Various Substances. 



In determining the above values the rays were first passed through one cm. of 

 Russell and Soddy, Philosophical Magazine, 21, p. 130, 1911. 



SMITHSONIAN TABLES. 



