320 Prof. Rutherford and Mr. Grier on Deviable 



give out both deviable aud non-deviable rays, due to the 

 excited radioactivity produced on it. 



The amount of deviable rays for equal weights of different 

 thorium compounds was found to vary considerably, as the 

 following table shows : — 



Compound. Amount of Deviable Bays. 



Oxide 1 



Deemanated oxide 1*35 



Nitrate '94 



Sulphate -83 



Oxalate *76 



Uranium oxide 6'7 



In the above table the amount of deviable rays from 

 ordinary thorium oxide is taken as unity, and the others 

 expressed in terms of it. For the purpose of comparison the 

 amount of deviable rays from an equal weight of black 

 uranium oxide is added. 



The comparisons in the above table were not made directly 

 by noting the effect of a magnetic field, but by an indirect 

 method, explained in § 9, which is based on the observed fact 

 that the penetrating rays from thorium as well as uranium 

 are chiefly deviable rays. 



Four grammes of the compound in the form of powder 

 were uniformly spread in a lead vessel of area 22 sq. cms. 

 A layer of aluminium, thickness *006 cm., was waxed down 

 over the top. This absorbed all the non-deviable rays, but 

 allowed most of the deviable rays to pass through. The 

 ionization-current due to these penetrating rays was deter- 

 mined in the usual way, and was taken as a measure of 

 their intensity. 



The deemanated oxide, i e. the oxide which had been 

 largely deprived of its power of giving off a radioactive 

 emanation by raising it to a white heat, gives more deviable 

 rays than the ordinary oxide ; while the nitrate is nearly as 

 active as the ordinary oxide, although containing only about 

 half the amount of thorium. 



It was also found that the increase of deviable rays with 

 time, when the thorium was kept in a closed vessel for 

 24 hours, varied very considerably for different compounds. 

 The increase was much greater for the ordinary oxide than for 

 the deemanated sample, while thorium carbonate, which gives 

 out five times as much emanation as the oxide, show r ed still 

 greater differences. 



This increase of deviable rays with time in a closed vessel 



