THE EVOLUTION OF MATTER 209 



result of a process of condensation or aggregation due to 

 the steady action of Force of Attraction. 

 Several possibilities suggest themselves. 



I. That no element evolved from a preceding one in 

 the table, but that each case came from some primitive 

 element-type which has disappeared. That the known 

 elements are fixed species at the ends of side-paths. 



II. That each element did actually evolve from some 

 preceding one in the list. 



III. That each group (vertical series in the table) indicates, 

 or is a special line of, past evolution. 



IV. That in the ascending order of their atomic weights 

 the elements represent links in a past evolutionary line. 



It may be noted with respect to the third possibility that 

 Lithium can be obtained from Copper in group 1 ; and 

 Thorium and Zirconium can be made to produce Carbon 

 in group 4. But, on the other hand, Radium can give rise 

 to Helium, and Thorium to Helium, in both cases to an 

 element of a different group. 



It is not unreasonable to conclude that the recurring 

 similarity of characters in every eighth element is based on 

 some recurring similarity of atomic internal plan or arrange- 

 ment. There is, so to speak, a repeating cycle of general 

 characters. This is indicated in the matter of the hydrides, 

 for in a given series of eight elements the difference in 

 hydrogen combination increases to its highest in the fourth 

 element, and then decreases by regular steps till the eighth 

 is reached, whose highest hydride is the same as that of the 

 first element of the series. In a different way the oxides 

 also indicate a character cycle which may well be based on 

 a repetition of internal atomic plan. Experiments which 

 have been made with floating magnets of various numbers, 

 and all of similar polarity, give distinct colour to the supposi- 

 tion. For when controlled by a bar magnet of opposite 

 polarity, held above the water, the floating magnets take 

 most interesting arrangements according to their numbers ; 

 and if the numbers are steadily increased, past arrangements 

 reappear on a larger scale. 



The Periodic Law would certainly seem to indicate that 

 the elements have evolved, and that a feature of this 

 evolution has been the larger and larger aggregation of 



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