Contemporary Advances in Physics, XXII 



Transmutation 



By KARL K. DARROW 



In this paper are described experiments made at the Cavendish Labora- 

 tory, in Vienna, in Chicago and elsewhere during the last fifteen years in 

 which atom nuclei have been disrupted by swiftly moving alpha particles 

 ejected by radioactive materials. Whether an atom is an atom of gold, or 

 of tin, or of praesodymium, or one of some other of the ninety-two varieties 

 is determined solely by the magnitude of its nuclear charge. 



When the disruption of atom nuclei occurs spontaneously, as it does 

 among atoms of the radioactive elements, the fragments are nuclei of 

 charge different from that of the exploded atom. When disruption is 

 brought about by design, as it is in the experiments described in this article, 

 we have again the disappearance of atoms of one species and the appearance 

 of atoms of other species. The cases differ in that in the first the action goes 

 on without let or hindrance, while in the second it is, to a certain extent, 

 under the control of the experimenter. The experimenter may, if he 

 chooses, congratulate himself on having solved the age old problem of the 

 transmutation of elements. However, transmutation as such is not the 

 object of these investigations. If it were their success would have to be 

 rated as altogether negligible, for the quantities of material transmuted are 

 much less than can be detected chemically. 



The real object of the work, as is made abundantly clear, has been to verify 

 and to extend our knowledge of the constitution of the nucleus. This is a 

 subject about which a great deal is yet to be learned, but one on which the 

 physicist has already many strong convictions based on a considerable array 

 of interrelated and consistent data. The various conclusions regarding the 

 constitution of atom nuclei which had been reached before any of these ex- 

 periments on artificial disintegration were made, are discussed. The results 

 of the investigations described confirm and extend our knowledge of the 

 constitution of the nucleus. 



IT is often said that the conversion of the elements into each other has 

 been the dream of the human race for many centuries, nay even for 

 millennia. In special and practical cases, this is probably true; I 

 suppose that from the dawn of history most men possessed of stores of 

 lead or silver have tantalized themselves by dreaming of these being 

 changed to gold. But in the general sense it must be false. One can- 

 not aspire to transform element into element, if one does not know what 

 elements are; and no one had such knowledge centuries ago. Surely 

 many of the chemical reactions which we consider commonplace, 

 many of the compounds old and new which the modern chemist makes 

 in his routine, would have seemed to ancient or to mediaeval no less 

 wonderful than any "transmutation" which he could possibly imagine. 

 Could the Florentine or the Greek have been much more amazed by a 

 change of silver into copper, than by the synthesis of a dye out of tar 

 or coal, the growth of a diamond out of black carbon in a furnace? 



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