\ Q ADVENTURES IN RADIOISOTOPE RESEARCH 



nium, which many years earher was in the center of interest of Paneth 

 and myself. Also, Irene Curie worked in the laboratory of her mother. 

 WhenI saw her in 1938, she mentioned that by neutron bombardment 

 of thorium she had obtained a lanthanum-like radioactive body. I asked 

 her if she was sure that this substance was not actinium. She answered 

 that she was pretty sure she was dealing with an element much lighter 

 than one of the radioactive disintegration series. 



A few months later Otto Hahn and Strassman made their fundamental 

 discovery of nuclear fission. I first met Hahn in Vienna in 1913. Already 

 at that date he had made such important discoveries as the existence 

 of radiothorium and mesothorium and the separation of radioelements 

 by making use of the recoil phenomenon. The years to come, brought 

 new discoveries of great importance, many of them in collaboration with 

 Lise Meitner. When I asked Rutherford in 1912 whom of his students 

 he considered to be the most merited one, he answered without hesitation 



"Otto Hahn". 



On my way to Manchester I usually stopped in London. On such an 

 occasion I had the opportunity of being present in the House of Commons 

 at the introduction of the much discussed budget by Lloyd George, then 

 Chancellor of the Exchequer, who characterized his introduction of heavy 

 death duties and other taxes as "bringing rare and refreshing fruit"! 



I was also present when J. J. Thomson in April, 1913, delivered his 

 Bakerian Lecture in the Royal Society on the two neon parabolas ob- 

 tained in his positive ray studies. He did not make any allusion to the 

 analogy between the two neons and the isotopes in the field of radioacti- 

 vity. This omission induced me to write to him drawing his attention 

 to the analogy between the two kinds of neon, on one hand, and radium 

 D and lead, on the other. He stated in his answer that he did not share 

 my view. While not adopting the view that the heavier constituent of 

 neon was a compound NeHg, which could have given the observed ato- 

 mic weight within the limits of experimental error, Thomson was not 

 convinced that this explanation was absolutely excluded. As Lord Ray- 

 leigh remarks in The Life of Sir J. J. Thomson, he had always been 

 haunted by this suspicion about hydrogen compounds and, for that rea- 

 son, hesitated for a time to accept Aston's later results about isotopes 

 of other elements. When we were on a ski-trip at Finse in Norway, Aston 

 related that when he first succeeded in getting two lines on a mass 

 spectrum photograph - one indicating ^^C\, the other ^^C\ - Thomson 

 refused to look at the photograph, which, Aston added, was the most 

 beautiful one he ever obtained. Aston was an ingenious and most merited 

 experimenter, who was the first one to prove the complexity of the com- 

 mon elements. 



In 1914 Moseley moved to Oxford and, being much interested in 

 X-ray spectroscopy, 1 intended to work with him. We wanted to study 



