2 VVlLDE, Points of Chemical PJiilosophy. 



propose 258 as its atomic weight, as against 225 the 

 value assigned to it by Mme. Curie. 



Now, there is good reason to believe that neither of 

 these numbers is the atomic weight of radium. An 

 examination of the following table will show that, as a 

 consequence of the law of multiple proportions by which 

 the atomic weights of the series Hn and H2n are deter- 

 mined, there is a common difference of 23 between the 

 atomic weights of the series Hn, commencing with Ka, 

 to the final member Hg. In like manner there is a com- 

 mon difference of 24 in the strictly parallel series H2n. 



Hn 



H2n 



H = 



T Diff. 



He = 



2 Diff. 





- 6 





- 6 



. 0.7 Li = 



7 



. . 8 = G1 = 



8 





-16 





-16 



1 x 23 . o = Na = 



23 



1 x 24 — 0= Mg = 



24 





-16 





-16 



2 x 23 — 7 = Ka = 



39 



2 x 24 — 8 = Ca = 



40 



3x23-7 = 011 = 



-23 

 62 



3 x 24 — 8 = Zn = 



-24 

 64 



4 X23-7 = Rb = 



-23 

 35 



4x24— 8 = Sr = 



-24 

 88 



5X23-7 = Ag = 



-23 

 108 



5 X 24 — 8 = Cd = 



-24 

 1 12 



6x 23 — 7 = Cs = 



-23 

 131 



6x 24-8 = Ba = 



-24 

 136 



7x23-7= — = 



-23 

 154 



7 x 24 — 8 = — = 



-24 

 160 



8x23-7= — = 



-23 



177 



8x24-8 = Ra = 



-24 

 184 



9X23-7 = Hg = 



-23 

 200 



9x24- 8 = Pb = 



-24 

 208 



I have already discussed the remarkable alternation 

 of light and heavy metals in regular order observable in 



