322 Prof. Rutherford and Mr. Grier on De viable 



The results for both thorium- and radium-excited radiation 

 show that the deviable rays decay at nearly the same rate as 



Fi°r. 2. 



the non-deviable. This result shows that there is a very 

 close connexion between the production of these two types of 

 radiation. 



§ 6. Active Products Separated from Thorium and Uranium. 



In a previous paper (Rutherford and Soddy, Proc. ('hem. 

 Soc, Jan., and Trans. Chem. Soc, April 1902) it has been 

 shown that a very active product can be separated from 

 thorium as a result of the precipitation of thorium nitrate by 

 ammonium hydroxide. If the filtrate, free from thorium, is 

 evaporated down to dryness and the ammonium salts driven 

 off by ignition, a very small residue is obtained intensely 

 active, possessing in some cases 1000 times the activity of 

 thoria. This radioactive fraction has been termed Thorium X. 

 At the same time the radioactivity of the precipitated thoria 

 is diminished in most cases to about -36 of its original 

 value. 



The investigation on the radioactivity of thoria has been 

 continued by E. Rutherford and F. Soddy, and at the same 

 time parallel experiments have been made on the partial 



