Sir Francis Simon (2 July 1893 – 31 October 1956), was a German and later British physical chemist and physicist who devised the gaseous diffusion method, and confirmed its feasibility, of separating the isotope Uranium-235 and thus made a major contribution to the creation of the atomic bomb. Early life Born Franz Eugen Simon to a Jewish family in Berlin, Franz was the son of Ernst Simon and Anna Mendelssohn, daughter of the mathematician Philibert Mendelssohn. Two of his cousins, Kurt Mendelssohn and Heinrich Mendelssohn, were also scientists. He won the Iron Cross First Class during World War I. He received his doctoral degree from the University of Berlin, working in the research group of Walther Nernst on low-temperature physics related to the Nernst Heat Theorem (Third law of thermodynamics). In 1931 he was appointed Professor of Physical Chemistry at the University of Breslau. Emigration The rise of anti-Semitic fascism in Germany in the 1930s caused him and his wife to consider emigrating. Aware of his concerns Frederick Lindemann, 1st Viscount Cherwell met him in Walther Nernst's laboratory during Easter 1933, and invited him to join the Clarendon Laboratory at the University of Oxford. He was also able to offer him a two-year grant research from Imperial Chemical Industries (ICI) of £800. Simon resigned on 1 July 1933, but before he could leave an official demanded that he and his wife surrender their passports. Simon then flung his Iron Cross and other medals onto the table. Their passports were later returned, for reasons unknown. Using the services of a corrupt customs official Simon was able to take his research equipment with him. His wife and children followed him two months later. Upon arrival in the UK, he started using the Anglicised name "Francis". Work in England Using the equipment he had brought with him from Germany he performed pioneering work in low temperature physics. In 1936 he was able to produce the first liquid helium by using magnetic cooling at a laboratory at Bellevue near Paris. His ICI grant was extended to 1938 which allowed him to turn down an offer of a 10-year contract as Professor of Physical Chemistry at Istanbul. In 1936 despite being supported by Einstein, Nernst, Planck and Rutherford he was unsuccessful in beating Mark Oliphant for the Chair of Physics at Birmingham University. His job security in Oxford improved in 1936 when he was appointed