WORK ON RADIUM 165 



gestion that the elementary atoms of copper and lead 

 undergo a process of degradation, the former into 

 sodium and lithium, the latter into products not finally 

 identified. Thorium nitrate submitted to the same 

 action continually produces carbon dioxide. At the 

 same time the helium which is evolved when emanation 

 is left alone or in admixture with oxygen and hydrogen 

 gases is replaced by argon when a copper salt is simul- 

 taneously present in solution. Other suggestions are 

 made in this important paper, and letters to his friend 

 Worthington give evidence of the fermentation which 

 this interesting subject set up in his mind. Thus, the 

 following passage occurs (21st Nov., 1906) : 



" I have the first proof that lead nitrate plus emanation gives 

 C0 2 . I am, of course, repeating. Other things don't, so far as 

 I have tried them, except thorium nitrate. . . . The order of 

 events appears to be : radium emanation, which is obviously 

 an argon gas, gives, when it disintegrates besides Rutherford's 

 A, B, C, etc., about 7'5 p.c. of its weight of He. CuS0 4 . Aq 

 plus emanation gives LigSC^, and now Pb(N0 3 ) 2 and Th(N0 3 ) 4 

 give C0 2 . I think that the pouring of such thundering amounts 

 of energy as come off the Ra emanation into these atoms (counting 

 these 7' 5 p.c. of the Ra emanation as also affected by the energy 

 given off by the odd 92*5 p.c. which disintegrates) brings them 

 down to their lowest members. 



Thus Li is the lowest member of the Cu group. 

 j? .tie ,, ,, ,, A. ,, 



C Pb and Th groups. 



Other members may be formed simultaneously. I think that 

 Na is also formed from Cu. I can't tell whether A or Kr are 

 formed from Em n , or whether Si, Ti, etc., are formed from Pb 



