18 LIFE: ITS NATURE AND ORIGIN 



Then Dr. Niels Bohr (Nobel prize, 1922) developed his quan- 

 tum theory of spectra, referred to by Rutherford as one of the 

 greatest triumphs of the human mind. Within ten years all the 

 main features of optical spectra were understood, largely helped 

 by the application of wave mechanics by Werner Heisenberg 

 (Nobel prize, 1932), Erwin Schrodinger (Nobel prize, 1933), and 

 P. A. M. Dirac (Nobel prize, 1933). 



Rutherford and Atomic Transmutation 



In 1919 Rutherford made the astounding discovery that when 

 light atoms are bombarded by alpha particles shot out at very high 

 speeds from radioactive substances, scintillations could be detected 

 in a device called a "cloud chamber." When nitrogen was the 

 gas bombarded, these scintillations struck out 40 centimeters or 

 more. By subjecting these new "rays" to the action of a magnetic 

 field and observing their deflection, Rutherford found that they 

 had the mass and charge of protons — that is, they were hydrogen 

 nuclei. His explanation was that when the helium nucleus (alpha 

 particle) enters the nucleus of a nitrogen atom, the nitrogen 

 nucleus is forced to eject a proton. The final result is a nucleus 

 with a positive charge of 8 and a mass of 17 — one of the isotopes 

 of oxygen. 



Professor Harvey E. White writes: 7 "The discovery of the dis- 

 integration and transmutation of stable elements by controlled 

 experiments is attributed to the great experimental genius, Sir 

 Ernest Rutherford. Outsiders might say the discovery was an 

 accident, but to those who knew him well it was the result of a 

 long series of well-planned experiments. True, he did not pre- 

 dict the phenomenon and then discover it, but his long experi- 

 ence with radioactivity and his keen insight enabled him to 

 recognize the meaning and importance of the phenomenon when 

 it was first observed. Due credit must also be given to the admir- 

 able work of his collaborators and to experimenters in other 

 laboratories who have since carried the work much further." 



And I cannot refrain from repeating here what some scientific 

 wag wrote of Rutherford: 



He made plain the invisible; 

 He broke up the indivisible; 

 He changed the immutable; 

 And he unscrewed the inscrutable. 



