126 MR, H. WILDE ON THE 



and mercury are more nearly allied to those of silver than 

 to metals of other groups, and recent investigations have 

 shown that silver may^ like copper, be regarded as biva- 

 lent, since many of its compounds can be represented by 

 formulae exactly analogous to those of cuprous compounds 

 with which they are isomorphous ■^. The position of Hg, 

 Ag, and Cu, as alternate members of the series Jin, indi- 

 cate their relationship with sodium, and are thereby 

 brought into still closer connexion with Li, K, Rb^ and 

 Cs. That a relationship exists between sodium and silver 

 by the isomorphism of their anhydrous sulphates and 

 in other ways, has already been pointed out by Odling. 

 The greater specific gravity of sodium, while possessing a 

 lower atomic weight than potassium, its passivity in the 

 liquid state to the action of chlorine f, and its inferior 

 volatility and oxidability to K, confirm the relationship of 

 Na to the heavy metals of the series. 



From what cause elements possessing physical proper- 

 ties so widely different should be associated alternately in 

 regular order in the same series, can only, in the present 

 state of knowledge, be a subject of speculation ; but, if 

 the views which I have enunciated on the formation of the 

 types Hn — Hyn be correct, it may be conceived that after 

 the transition of the cosmical vapours from the spiral to 

 the annular form, the gaseous material of each pair of 

 members might rotate in concentric zones, separate from 

 each other by an interval of space. It may be further 

 conceived that the rotating zones of elementary matter 

 were of sufficient thickness to cause a difference of density 

 between their upper and lower regions. That the zones 

 were in a highly electrical condition, and that their mu- 



* " Quantivalence of Silver, — Wislicenus," Watts , Die. Cbem., 2nd Suppl. 

 1088. 

 t Watts, Die. Chein., Suppl. 1030. 



