CONTEMPORARY ADVANCES IN PHYSICS 157 



sorbed into the fragments — "disintegration with capture" — and even 

 to estimate {Tx — To), which turns out to be usually if not always 

 negative. There are some difficulties here, since in certain cases the 

 process which is observed seems to be the converse of one of the well- 

 known processes of generating neutrons, and yet (Ti — To) does not 

 appear to have values equal in magnitude and opposite in sign for the 

 two. The most startling feature of transmutation by neutrons is, 

 that it occurs with nuclei which seem to be immune to other transmut- 

 ing agents, notably carbon and oxygen. Other elements with which it 

 occurs are nitrogen, fluorine, neon, chlorine and argon. 



Acknowledgments 



I am greatly indebted to Monsieur F. Joliot, Professor E. O. Law- 

 rence, Dr. J. R. Dunning and Dr. P. I. Dee for providing me with 

 prints of several of the photographs which appear in this article (Figs. 

 1, 4, 5, 6, 14, 15); and to Dr. Dunning for criticism and advice in 

 respect to several sections of the text. 



References 



Transmutation by Protons and Deutons 

 Cavendish school: 



J. Cockcroft & E. T. S. Walton: Proc. Rov. Soc. A129, 477-489 (1930); 136, 



619-630 (1932); 137, 229-242 (1932). 

 P. I. Dee: Nature 132, 818-819 (25 Nov. 1933). 

 P. I. Dee & E. T. S. Walton: Proc. Roy. Soc. A141, 733-742 (1933). 

 M. L. E. Oliphant & E. Rutherford: Proc. Roy. Soc. A141, 259-281 (1933). 



The same with R. B. Kinsey: ibid. 722-733. 



Berkeley school: 



M. C. Henderson: Phys. Rev. (2) 43, 98-102 (1933). 



E. O. Lawrence & M. S. Livingston: Phys. Rev. (2) 40, 19-35 (1932). 



Letters and abstracts by E. O. Lawrence, M. S. Livingston, M. G. White, 

 G. N. Lewis, M. C. Henderson: Phys. Rev. (2) 42, 150-151, 441-442 (1932); 

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 783 (1933). 



Other schools: 



H. R. Crane, C. C. Lauritsen & A. Soltan, Phys. Rev. (2) 44, 514 (1933) (effect 



of He+ ions); ibid. 692-693; Crane & Lauritsen, ibid. 783-784; 45, 63-64 



(1934). 

 C. Gerthsen: Naturwiss. 20, 743-744 (1932). 



F. Kirchner: Phys. ZS. 33, 777 (1932); 34, 777-786 (1933); with H. Neuert, 



34, 897-898 (1933). Sitzungsber. d. kgl. Bdyrischen Akad. 129-134 (1933). 

 Naturwiss. 21, 473-478, 676 (1933). 

 H. Rausch v. Traubenberg, R. Gebauer, A. Eckart: Naturwiss. 21, 26 (1933); 

 ibid. 694. 



Transmutation by Alpha-Particles 

 Transmutation with emission of protons: 



P. M. S. Blackett: Proc. Roy. Soc. A107, 349-360 (1925). 



W. Bothe: ZS. f. Phys. 63, 381-395 (1930); Atti del convegno di fisica nucleare, 



Roma, 1932. 

 W. Bothe & H. Franz: ZS.f. Phys. 43, 456-465 (1927); 49, 1-26 (1928). 



