Introduction: From Rutherford to Hahn

Abstract

When Otto Hahn went abroad to work with Ernest Rutherford at McGill University in Montreal in the autumn of 1905 he was already twenty-six years old and had been a doctor of chemistry since 1901. The organic chemist Theodor Zincke had supervised his research at Marburg, and after Hahn returned from military service in 1902, he had offered him an appointment as his laboratory assistant, to give him sufficient experience to qualify for employment in one of Germany’s large chemical firms. In 1904, the head of Kalle and Company mentioned to Zincke that they would like to hire a young chemist but that the candidate would have to be familiar with a foreign country and be fluent in a second language. Zincke suggested to Hahn that he go to England to learn English and to work under Sir William Ramsay, the famous discoverer of the inert gases, with whom Zincke entertained friendly relations. Hahn arrived at the Chemical Institute of University College in London in the autumn of 1904, and Ramsay immediately asked him whether he wanted to work with radium. When Hahn replied that he did not know anything about radium, Ramsay said that this would do no harm since it would enable him to approach the project with an open mind. He handed Hahn a 100-gram specimen of barium chloride and told him to use Marie Curie’s method for extracting radium. She had found that radium is slightly more difficult to dissolve than barium, but when recrystallized it precipitates more abundantly, although always with barium. If the process is interrupted and then restarted, a noticeable enrichment of radium can be obtained after several repetitions. This technique, known as fractional crystallization, was the one that Hahn rapidly mastered.