194 SUPER-ORGANIC EVOLUTION 



eighth group in Mendeleef s system 1 are situated 

 around three of the ten nodal points. 



" This group is divided into three ternary series : 

 iron, nickel, and cobalt; rhodium, rutenium, and 

 palladium ; iridium, osmium, and platinum. 



"These bodies are interperiodical, for their 

 atomic weights exclude them from the short periods 

 in which the other elements are included, and 

 their relations with some of the neighbouring 

 groups show that they are probably interperiodical 

 on account of this transition state." 



This diagram of Crookes is very explanatory, and 

 discloses the regularity and real function of matter, 

 which is highly curious and instructive. 



Following the course of the screw, starting from 

 hydrogen, it is surprising to see how the bodies 

 succeed one another, not only according to the order 

 which their atomic weight marks out for them, 

 which is seen in the axis of the screw, but at the 

 same time keep appearing according to their 

 atomic values. Thus proceed in order the mon- 

 atomics ; then the diatomics, triatomics, and tetra- 

 tomics ; following the curve of the screw, their 

 atomic values increase, and the triatomics, diatomics, 

 and monatomics appear, so as to stop, in this flux 



1 This group is outside of the said table, and includes Fe, Co, Ni, Ru, 

 Rh, Pd, Os, Ir, Pt, forming three groups that answer to the second, third, 

 and fifth horizontal columns, 



