Wellisch and Bronson — Active Deposit of Radium. 483 



Art. XLII. — The Distribution of the Active Deposit of 

 Radium in an Electric Field ; by E. M. Wellisch and 

 J3. L. Bronson. 



1. Introductory. 



The present paper contains the results of a series of experi- 

 ments which were carried out at the Sloane Physical Labor- 

 atory of Yale College, and which were undertaken with a view 

 of throwing light on the mechanism involved in the transmis- 

 sion 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* 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 radio-active disintegration ; in particular, an attempt was 

 made to explain on this theory the experimental result 

 obtained by Rutherfordf 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 elec- 

 trodes could be affected in any way by the application of an 

 extraneous source of ionization such, for instance, as that pro- 

 duced by causing intense Kontgen 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 ionization has so 

 far been found to produce little or no effect on the distribution 

 of activity, nevertheless a decided interaction has been found 

 to take place between the restatoms and the ions produced by 

 the radiations which accompany the formation of these 

 particles. 



The results of previous experimenters with regard to the 

 distribution of the active deposit under various conditions have 

 shown a lack of agreement which in our present experiments 

 has been traced to the fact that the potentials employed were 

 often far from sufficient to saturate even approximately the 

 radio-active ions. 



* Wellisch, Verh. Deutseh. Phys. Ges., xiii, p. 159, 1911. 

 f Kutherford, Phil. Mag. (6), v, p. 95, 1903. 

 tFranck, Verh. Deutsch. Phys. Ges., xi, p. 397, 1909. 



