INTRA-ATOMIC ENERGY. 273 



that the products of dissociation .showed no trace of sodium. If, 

 then, the effluvia of radio-active bodies are matter, such matter pos- 

 sesses none of the properties of that from which it was derived. 



Max A]>i'aham and Kaufman n proved that the dissociated atoms of 

 radio-active phenomena are transformed into something- extremely dif- 

 ferent from matter, and which the}" consider to be composed exchisivel}' 

 of atoms of electricity; that is to say, of what one to-day calls electrons, 

 bodies without weight, which differ essentiall}^ from ordinary matter, 

 having no character in common with it except a certain amount of 

 inertia. 



Inertia is, as is well known, the resistance, whose cause is unknown, 

 that bodies oppose to movement or change of movement. It can be 

 measured and its measure is defined by the term "mass." Mass,' 

 then, is the measure of the inertia of matter, its coefficient of resist- 

 ance to movement. It has an invariable value for every material bod}', 

 one which remains invarial)le throughout all the transformations to 

 which that body may be sul)jected. Constancy of mass is, as I inen- 

 tioned above, one of the fundamental principles of mechani(%s and of 

 chemistry. 



Now, this property possessed by the material atom is also possessed 

 by the electric atom to a certain degree. For some years it has been 

 admitted that electricity is endowed with inertia. It is, indeed, by 

 means of this property that we explain the phenomena of induction 

 and of oscillating discharges. We are ignorant whether that inertia 

 has the same unit of measure as the inertia of matter. Some physi- 

 cists suppose, without, indeed, being able to offer any proof, that the 

 inertia of matter is due to the electrons and is entirely of electro- 

 magnetic origin. 



It does not seem, however, that we can identify the inertia of mat- 

 ter with that of the electric atom whose mass is, in reality, only an 

 apparent mass, resulting simply from its state of an electrified body 

 in movement. The electric corpuscle seems to have a longitudinal 

 mass (measured l)y opposition to acceleration in the direction of 

 motion) different from its transversal mass (perpendicular to the direc- 

 tion of motion). It is clear that the properties of an electi-ic atom 

 differ considerably from those of a material atom. 



What, then, is the constitution of these h3'pothetical electric atoms 

 emitted by all ])odies during radio-activity^ 



The answer to that cpiestion will fui'nish us with exactly the link 

 between the pondtu'able and th(» ini])oiiderable, for which we are 

 searching. 



It is evidently impossible, in the present state of our knowledge, to 

 define an electric atom, but we can at least characterize it thus: A 

 substance that is neither a solid, a liquid, nor a gas, that has no 

 weight, that traverses obstacles without difficulty, and that has no 



