ORIGIN OF ELEMENTARY SUBSTANCES. 143 



and is only arrived at after much research^ the septivalency 

 of ^manganese indicates a much higher quantivalence for 

 the other members of the series Hjn than has up to this 

 time been accorded to them. 



I have hesitated to introduce hypothetical elements 

 alternating with the iron, palladium, and platinum groups, 

 as the regular sequence of elementary forms is broken by 

 varieties, and from the density of the typical molecule 

 H7, it may be that the members of this series are limited 

 to those shown in the table. The density of the typical 

 molecule Hbn may also explain the absence of members 

 alternating with Cr, Mo, and W, and I have therefore 

 only introduced one hypothetical element in this series, 

 the analogue of Cr, with the atomic weight=i44. 



Considering how nearly the numbers representing the 

 molecular constitution and atomic weights of the members 

 in homologous positions in the higher groups approximate, 

 the idea occurs that the subsequent condensations of these 

 higher groups are in some way influenced or determined 

 by the antecedent condensations of homologous members 

 of the lower groups, and may be the cause of the departure 

 in the higher groups from the simple ratios and multiple 

 relations observed amongst the elements of the series Hn 

 and Hin. Such perturbations would appear to be similar 

 to those which the planetary bodies exercise on each other 

 to produce modifications in the forms of their orbits, but 

 I leave this question to the further consideration of physi- 

 cists and astronomers. 



The complete parallelism of the halogens and oxygens to 

 each other, and their intensely electro-negative character, 

 point irresistibly to the conclusion that at one period of 

 their history these elements existed in a state of isolation 

 from all the others. How, and under what conditions, 

 they acquired their electro-negative properties can in the 



