On the History of the Franck & Hertz Experiments

A look at Franck and Hertz's famous experiments, conducted between 1912 and 1914, will be taken. Also, the different reactions of other physicists (including Niels Bohr) who extended the experiments during the First World War will be described. The interpretational shift that Franck and Hertz needed to cope with is analyzed as well. In the end, it will be shown the experiments together comprise one extended argument about the ionization properties of gases. Although Franck and Hertz's interpretation was wrong, their experimental skills were impressive. The experiments can be seen as an example that experimentation cannot be done without the presence of an interpretation.