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XXVII. The Production of Cathode Particles by Homogeneous 

 Rontgen Radiations, and their Absorption by Hydrogen and 

 Air. By R. T. Beatty, M.A, B.E., 1851 Exhibition 

 Scholar, Emmanuel College, Cambridge *. 

 [Plate V.] 



THE properties of the cathode particles produced when 

 Rontgen radiations fall upon various substances have 

 been investigated by several physicists. The work of 

 Cooksey f and Innes % has shown that the velocities of these 

 cathode particles are independent of variations in the in- 

 tensity of the Rontgen radiations used, and also independent 

 of the nature of the substance struck by these radiations, 

 but that the velocities increase with an increase in the 

 penetrating power of: the exciting Rontgen radiations. 



The work of Barkla and Sadler upon homogeneous radia- 

 tions enables one to use beams of definite quality and differing 

 widely in penetrating power, and it seemed that by using 

 such beams more precise information might be gained about 

 the cathode particles emitted from metals placed in the path 

 of such beams. 



In view of the anomalous behaviour of hydrogen with 

 regard to ionization phenomena, it was determined to in- 

 vestigate the coefficients of absorption by hydrogen and air 

 of the cathode particles emitted from a sheet of silver leaf 

 which was placed in the path of the homogeneous radiations 

 described above. 



The homogeneous radiations from the 

 Zn, As, Sn, were excited by suitable 

 Rontgen bulb. 



metals Fe, Ni, Ou, 

 radiations from a 



A homogeneous radiation so produced entered the cylin- 

 drical ionization chamber A (fig. 1) through a thin parch- 

 ment window. It then passed through a silver leaf, and 



* Communicated by Prof. Sir J. J. Thomson. 



t C. D. Cooksev, Amer. Jour. Sci. [4 J xxiv. 1907, p. 285. 



\ P. D. Innes, Roy. Soc. Proa, ser. A. lxxix. pp. 442-462, Aug. 2, 1907. 



