498 Wellisch and Bronson — Active Deposit of Radium. 



for by the formation of neutrons and ions in different propor- 

 tions along the entire range of the a-particle. 



8. Summary. 



(1) The distribution in an electric field of the activity result- 

 ing from a long exposure to the emanation of radium has been 

 determined for various conditions of pressure, potential, etc. 



(2) There appear to be no negatively charged carriers, 

 all the so-called anode activity being due to the diffusion of 

 uncharged carriers. 



(3) The effect on the distribution obtained by causing Ront- 

 gen rays to pass through the gas during the exposure has been 

 investigated ; this effect was appreciable only when the activity 

 and ionization were far from saturation. 



(4) The difficulty of obtaining saturation both for the cath- 

 ode activity and for the a -ray ionization currents has been 

 explained as being due to the formation by the a-particle of 

 neutrons, some of which are subsequently resolved into ions, 

 probably by collision with ions already established in the 

 columns. 



