18 ADVENTURES IN RADIOISOTOPE RESEARCH 



had to decide on a name for the new institute, he hesitated between 

 "Theoretical Physics" and "Atomic Physics". His choice fell on the first 

 one ; he felt that the latter might be too exacting and possibly too special 

 as well. In front of the Technological Institute there is a statue of Olaus 

 Romer, the first physicist to measure the velocity of light. I once pointed 

 out when passing this monument that space is available for a future 

 monument of Niels Bohr. My companion smiled at this remark. Today 

 he would not smile any more. 



It was settled with Bohr that I should be back in Copenhagen in the 

 spring 1920, to start activities at the new institute which was to be opened 

 by that date. I spent the remaining six months with my friend Zech- 

 meister in Budapest carrying out exchange studies by the application 

 of radioactive indicators. When dissolving in water both 1 mol of labelled 

 lead nitrate and 1 mol of non-radioactive lead chloride, or labelled lead 

 chloride and non-radioactive lead nitrate, after separation of the two 

 compounds, we found the radioactivity equally distributed between 

 PbCla and PbNOg. When dissolving non-radioactive tetraphenyl lead 

 and radioactive lead nitrate, after separation all radioactivity was con- 

 served in the nitrate sample, as the lead atoms of tetraphenyl lead are 

 not exchangeable. When I met Svante Arrhenius in 1922 he told me 

 about his interest in the above-mentioned work. The experiments with 

 labelled lead chloride and non-labelled lead nitrate, or vice versa, are 

 the most direct proof of the correctness of the theory of electrolytic 

 dissociation. 



After the war, I was anxious to go to England as soon as possible. The 

 atmosphere at that time, however, radically differed from the one that 

 prevailed after the second World War. When in 1921 I wrote from Copen- 

 hagen to Rutherford, a very liberal man, that I wished to visit England, 

 he answered that it was still too early for a former enemy to come to 

 England. In 1923, however, when he was elected president of the British 

 Association meeting which was to take place in Liverpool, he invited 

 me to address that meeting on the discovery of hafnium. I recall a lunch 

 party at Liverpool in which Lord and Lady Rutherford, Niels Bohr, 

 Millikan, Aston, Coster, and myself took part. Lady Rutherford remarked 

 that this party included four Nobel Laureates. Rutherford added, 

 "And some embryos". 



Rudolf Schoe nheimer 



During my stay in Liverpool I was told about the work of Blair- 

 Bell who claimed a successful cancer therapy through administration 

 of lead compounds. These results induced me, when I worked at the 

 University of Freiburg some time later, to study the distribution of 

 labelled lead compounds between cancerous and normal tissue. A study 



