MODERN ALCHEMY. 141 



must have faith in their " facts." Such are the men upon 

 whose ipse dixit the facts of the science of radio-activity 

 mainly rest. They are distinctly men of credibility. Hav- 

 ing confidence, then, in their statements of fact let us ex- 

 amine into them. 



We discover that there exists in nature a certain well- 

 known " element/' uranium. This element is radio-active; 

 that is, it has the power of continuously emitting rays. 

 These rays are of two kinds: one, the positively electrified 

 and slightly penetrating alpha-rays, and the other the highly 

 penetrating and negatively electrified beta-rays. 



By methods of chemical fractionation somewhat similar 

 to that by which radium is isolated from pitchblende, 

 it has been found possible to separate from this uranium 

 another substance altogether; and, furthermore, it turns 

 out that this separated substance is entirely responsible for 

 the beta-rays of the original uranium, the substance from 

 which it was extracted giving rise only to the alpha-rays. 

 The extracted substance is known as uranium X. This fact 

 is followed by another. The extracted uranium X gradually 

 but completely loses its power of emitting the beta-rays, 

 and at such a rate that half of it has disappeared in about 

 22 days; while, on the contrary, the uranium from which it 

 has been extracted regains this power at the very same 

 rate, and eventually becomes as potent as ever. After it 

 has been restored you may, if you like, extract a second 

 quantity of uranium X, and a third, and a fourth, and so 

 on, so far as is known, ad infinitum. This is a matter of 

 fact into which no theory enters. On the basis of this 

 fact, then, we seem compelled to conclude that the uranium 

 is continuously manufacturing from itself another substance, 

 uranium X, which has only a transitory existence; and 

 that the power of emitting these penetrating rays, which an 



