120 MR. H. WILDE ON THE 



II. 



0.0.7 Li 7 



1 X 23 ■ o = Na = 23 



2 X 23 - 7 = Ka = 39 



3 X 23 — 7 — Cu = 62 



4 X 23 — 7 = Rb = 85 



5 X 23 — 7 = ^g = J°^ 

 6x23 — 7= Cs =131 



7 X 23 - 7 = — = 154 



8 X 23 - 7 = — =177 



9 X 23 - 7 = Hg = 200 



Again, by multiplying in like manner the atomic weight 

 of the second member of the alkaline-earth and cadmium 

 group of metals, the products, minus the atomic weight 

 of the first member (Gl = 8), are the atomic weights of all 

 the elements of this group. 



III. 



0.0 . 8 := G\ = 8 



1 X 24 — o = Mg — 24 



2 X 24 — 8 = Ca = 40 



3 X 24 — 8 = Zu = 64 



4 X 24 - 8 = Sr = 88 



5 X 24 — 8 — Cd = 112 



6 X 24 - 8 = Ba = 136 



7 X 24 - 



160 



8 X 24 - 8 = — = 184 



9 X 24 — 8 = Pb = 208 



The further relations observable between interplanetary 

 voids and atomic condensations of the natural groups of 

 elements in Tables II., III., are as follows : — 



1. The regular geometric series of the planetary dis- 

 tances commences at the second member of the system^ 

 and the regular arithmetical series of atomic weights 

 commences at the second and corresponding member of 

 each group. 



2. As the atomic weight of the second element in each 

 group is half the sum of the atomic weights of the first 

 and third elements, so is the distance of the second 



