284 TNTKA- ATOMIC ENERGY. 



plio.sphoresccnt when pure. Augnieiited l)y traces of certain foreign 

 substances and submitted to the action of an elevated temperature 

 wliich produces dissociation of matter in all bodies, as I have shown 

 in a preceding' paper, these same sulphides soon become capable of 

 producing phosphorescence. These examples might l)e uudtiplied. 



We must not, then, ask chemistry to inform us as to the transforma- 

 tions that matter undergoes when it begins to become dissociated. It 

 is also evident that the only means possessed by that science are some- 

 times altogether too gross for the differentiation of bodies, and some- 

 times do not succeed in differentiating them at all. Nearly a quarter 

 of the elementary bodies already known — that is to say, about fifteen — 

 so ]'eseml)le each other in their chemical characters that without cer- 

 tain physical properties (spectroscopic lines, electric condiictibility, 

 specific heat, etc.) they would never have been separated. These bodies 

 are the metals whose oxides form what are called the rare earths. 

 "They are distinguished from each other," say Messrs. Wyrouboff 

 and Vernouil, " with some two or three exceptions, only l)v their 

 ph^'sical properties, and are found to be chemically identical. They 

 are so much so that by no reaction hitherto devised can they be sepa- 

 rated, and we are reduced to obtaining them in a more or less pure 

 state by the empirical and gross process of fractional distillation." 

 In no other manner, indeed, can we obtain radimn. 



If we marshal the facts cited we arrive at this conclusion — incon- 

 testable in the case of barium and radium, incontestable in the case of 

 certain phosphorescent bodies, almost incontestable in the case of 

 metals in a colloidal state — that reactions having- :for their probable 

 origin beginnings of atomic dissociation suffice to give to bodies abso- 

 lutely novel properties which none of our chemical reagents can 

 detect, and which were revealed only when now means of physical 

 investigation were discovered. Ordinar}' chemistry touches only, I 

 repeat, the structures formed b}" atoms and modifies them at its will. 

 If, however, it disposes at will of the stones of the structures, it does 

 not yet know how to affect the constitution of those stones. The 

 intra-atomic chemistry of the future will attempt the study of the 

 phenomena which take place within the atoms. In this new science, 

 of Avhich we ])arely discern the dawn, the old paraphernalia of the 

 chemists — their balances and their reagents — will probably remain 

 unemployed. 



Section K), — P/iasr's o^ existence erf ■/natter — Genesis and evolution of 



atoms. 



BirtJt a/td evolution of atoms. — It is hardly thirty ,vears since it 

 would have been impossible to write on this subject a single w^ord 

 deduced from any scientific observation whatever, and one might have 

 supposed that the history of aioms would always be enveloped in 



