﻿714 Profs. Wellisch and Bronson on the Distribution of 



properties of mercury vapour, the first being upon the fluor- 

 escence, etc. of the vapour (this journal, vol. xviii. p. 240), and 

 the second, on the selective reflexion of monochromatic light 

 by mercury vapour (torn. cit. p. 187). The investigation has 

 been made possible through a grant from the Rumlbrd fund 

 of the American Academy of Arts and Sciences, and my 

 thanks are due to the members of the Rumlbrd committee 

 for their generous aid. 



LXVUL The Distribution of the Active Deposit of Radium in 

 an Electric Field. By E. M. Wellisch, Assistant Professor 

 of Physics in Yale College, and H. L. Bronson, Professor 

 of Physics in Dalhousie College, Halifax*. 



1. Introductory. 



THE present paper contains the results of a series of 

 experiments which were carried out at the Sloane 

 Physical Laboratory of Yale College, and which were under- 

 taken with a view of throwing light on the mechanism 

 involved in the transmission of the active deposit of radium 

 to the electrodes in an electric field or to the exposed solid 

 surfaces in the absence of such field. .In order to account 

 for this transport of activity one of us f had already suggested 

 a theory in which the view was taken that the transmission 

 was effected as a result of the interaction between the active 

 deposit particles (or restatoms) and the ions formed in the 

 gas by the radiation accompanying the radioactive disinte- 

 gration ; in particular, an attempt was made to explain on 

 this theory the experimental result obtained by Ruther- 

 ford { and Franck § that the restatoms moved through the 

 gas with the same velocity as the positive ions. 



The original object proposed in the present experiment 

 was to ascertain whether the distribution of activity on the 

 electrodes could be affected in any way by the application 

 of an extraneous source of ionization such, for instance, as 

 that produced by causing intense Rbntgen rays to pass 

 through the gas. 



We might be permitted to anticipate here the results of 

 the present experimental investigation and to state that, 

 although the application of such extraneous source of ioni- 

 zation has so far been found to produce little or no effect on 



* Communicated bv the Authors. 



t Wellisch, Verh. Dents. Phys. Ges. xiii. p. 159 (191 1 ). 



X Rutherford, Phii. Maj>\ sfcr. 6, v. p. 95 (1903). 



I Franck. Verh, fiettts. P/ws. Ges. xi. p. 397 (1909). 



