﻿402 Scientific Intelligence. 



original cooling, we should have a nearer approach to the state 

 of the elemental family such as we know it at present. In this 

 way, it is conceivable that the succession of events which gave us 

 such groups as platinum, osmium and iridium — palladium, ruthe- 

 nium and rhodium — iron, nickel and cobalt — if the operation of 

 genesis had been greatly more prolonged would have resulted in 

 the birth of only one element of these groups. It is also proba- 

 ble that by a much more rapid rate of cooling elements would 

 originate even more closely related than are nickel and cobalt and 

 thus we should have formed the nearly allied elements of the 

 cerium, yttrium and similar groups; in fact the minerals of the 

 class of samarskite and gadolinite may be regarded as the cosmi- 

 cal lumber-room where the elements in a state of arrested devel- 

 opment — the unconnected missing links of inorganic Darwinism 

 — are finally aggregated." The author then goes on to draw 

 from the assumption already made that the original protyle con- 

 tained within itself the potentiality of all possible atomic weights, 

 the conclusion that our atomic weights represent merely a mean 

 value around which the actual atomic weights of the atoms vary 

 within certain narrow limits and hence that " each well-defined 

 element represents a platform of stability connected by ladders of 

 unstable bodies. In the first accreting together of the primitive 

 stuff the smallest atoms would form, then these would join together 

 to form larger groups, the gulf across from one stage to another 

 would be gradually bridged over, and the stable element appro- 

 priate to that stage would absorb as it were the unstable rungs 

 of the ladder which lead up to it. I conceive, therefore, that 

 when we say the atomic weight of, for instance, calcium, is 40, 

 we merely express the iact that w T hile the majority of calcium 

 atoms have an actual atomic weight of 40, there are not a few 

 which are represented by 39 or 41, a less number by 38 or 42 and 

 so on." If so, then might not these heavier and lighter atoms be 

 sorted out by a process resembling chemical fractionation ? In 

 answer to this question, Mr. Crookes gives the results of experi- 

 ments which he has carried on for several years on the separation 

 by fractional precipitation of the earths of samarskite and gado- 

 linite. "Down to a date comparatively recent," he says, "noth- 

 ing was more firmly fixed in my mind than the notion that yttria 

 was the oxide of a simple body ; and that its phosphorescent 

 spectrum gave a definite system of colored bands. Broadly 

 speaking there is a deep red band, a red band, a very luminous 

 citron-colored band, a pair of greenish-blue bands, and a blue 



band That the whole system of bands spelled yttria and 



nothing but yttria, I was firmly convinced. During the later 

 fractionation of the yttria earths and the continued observations 

 of their spectra, certain suspicions which had troubled me for 

 some time assumed consistent form. The bands which hitherto I 

 had thought belonged to yttria began to vary in intensity among 

 themselves and continued fractionation increased the differences 

 first observed. Whilst I was in this state of doubt and uncer- 



