THE 



t 



LONDON, EDINBURGH, ani> DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES.] fV* 



DEC 1719U 



DECEMBER 1914. \ , 



PA 



LXXXIII. The Distribution of the Active Deposit of Actinium 

 in an Electric Field. By A. N. LuciAN, Ph.D.' ( Yale) *. 



I. Introduction. 



THE observation first made by Rutherford, that the active 

 deposit of radium is to a large extent concentracted on 

 the cathode in an electric field, led naturally to the suppo- 

 sition that the deposit consisted of positively charged particles, 

 and that under suitable conditions the concentration could 

 be made complete. The results obtained by Wellisch and 

 Bronsonf and by Wellisch J separately showed that this 

 supposition is not justifiable. In the second paper cited, it 

 has been shown that the radium deposit atoms consist of 

 neutral and positively charged particles ; that even under 

 the most favourable conditions only a definite proportion 

 (about 90 per cent.) of the particles is deposited on the 

 cathode ; that there is distinct evidence of columnar or initial 

 as well as volume recombination, and that in general both 

 effects are much more pronounced for the case of deposit 

 particles and gas ions than for the gas ions among them- 

 selves. 



The work on the actinium active deposit had been quite 

 inconsistent from the beginning, and had given rise to various 

 views in regard to the origin and the sign of the charges 



* Communicated by Prof. E. M. Wellisch. 

 t Wellisch and Branson, Phil. Mag. vol. xxiii., May 1912. 

 1 Wellisch, American Journal of Science, vol. xxxvi., Oct. 1913 ; 

 Phil. Mag. vol. xxvi., Oct. 1913. 



Phil. Mag. S. 6. Vol. 28. No. 168. Dec. 1914. 3 D 



