152 THE NEW KNOWLEDGE. 



number of corpuscles constituting it, while it would be 

 opaque to other atoms. In other words, the absorbing 

 power of a substance must, therefore, on the basis of our 

 theory, be simply proportional to its density; and as 

 we find it so in fact, it makes our theory just so much the 

 stronger. Reinforced by this independent fact we can there- 

 fore go forward with good courage. 



In the preceding chapter we found that the element 

 uranium became continuously transmuted into a totally dif- 

 ferent element, uranium X, and that the same transmuta- 

 tion was true of other elements. Any given mass of the 

 element uranium consists simply of x or y atoms of that 

 element, and, hence, if there is a transmutation into any other 

 element, it must consist, simply, in the transmutation of the 

 atom of the first into the atom of the second. The trans- 

 mutation is entirely atomic. But this leads us to think 

 that the atom of any given element consists not only of 

 corpuscles but of systems of corpuscles. Take, for example, 

 the case of thorium. The atom of thorium breaks down 

 into the atom of thorium X with the evolution of material 

 particles that we call the alpha-rays. The atom of thorium 

 X, in its turn, breaks down into the atom of the thorium 

 emanation with the evolution of still more alpha-ray par- 

 ticles. The atom of the thorium emanation follows the ex- 

 ample of its predecessors in breaking down into the atom of 

 the thorium emanation X again with the evolution of alpha 

 particles; and the atom of the thorium emanation X itself 

 breaks down into some atom of an unknown type with 

 an evolution not only of the material particles of the alpha- 

 rays but of beta- and gamma-rays as well. The original 

 thorium must, therefore, be an exceedingly complex sys- 

 tem of corpuscles, system within system for it has within 

 itself the potentiality of at least five different atoms. This 





