274 INTRA-ATOMIC ENERGY. 



property in common with matter, except a certain inertia, and, what 

 i.s more, an inertia \ar3'ing' with the velocity, that is more like ether 

 than matter and forms a transition between them. 



The formation of effluvia is an incontestable testimony to the trans- 

 formation of the ponderable into the imponderal)le. 



This transformation, so contrary to all the precepts laid down by 

 science, is nevertheless one of the most frequent phenomena in natui'e. 

 It is dail}" effected under our eyes, l)ut as we formerly possessed no 

 reagent for testing it it w^as unoi^served. 



Section 6. — The current conception as to atoms. 



Orir/h) of current ideas concerning the structure of atoms. — Those 

 scientists who follow in foreign journals the experiments and discus- 

 sions of the most eminent physicists of the present day, such as Lord 

 Kelvin, J. J. Thomson, Crookes, Larmor, Lorentz, and many others, 

 have before them a curious spectacle. They see melting away before 

 them, da}" ]>y day, fundamental scientific conceptions that seemed estab- 

 lished solidly enough to remain forever. 



Being unal)le to give, in detail, the steps of this evolution, I will 

 confine myself to stating summarily the researches of which the present 

 theories seem the necessary consequence. 



Five fundamental discoveries were the origin of the transformation 

 of ideas concerning matter and electricity. These were, first, facts 

 revealed by the study of electrolytic dissociation; second, the discov- 

 ery of the cathodic rays; third, that of the X-rays; fourth, that of the 

 so-called radio-active bodies, such as uranium and* radium; fifth, the 

 demonstration that radio-activity is not a peculiar property of certain 

 bodies, but is a general property of matter. 



The oldest of these discoveries, since, indeed, it goes V)ack to Davy — 

 that is to say, to the commencement of the last century — is that of the 

 dissociation of chemical compounds by an electrical current. Its study 

 was completed later by various ph3\sicists, notably l)y Faraday, and, 

 in our time, by Arrhenius. It led on toward the theory of atomic 

 electricity and the preponderating influence which electric atoms or 

 electrons have in chemical reactions and the properties of ])odies. 



It seemed formerly that electric dissociation could only be obtained 

 from compound l)odies, never witli simple ones. Yet, as soon as the 

 cathodic rays and radio-activity Avere discovered, the theory of electric 

 dissociation seemed to explain them very well on the simple condition 

 of admitting that the atoms of a simple body contain, like those of a 

 compound body, electric atoms having contrary signs and susceptible, 

 like them, of separation. 



The second of these discoveries, that of the cathodic raj's, suggested 

 the idea that there might be a state of matter different from any 

 hitherto known; but this idea remained without infiueuce up to the 



