Fritz Haber

Fritz Haber was a German chemist who on 2 July 1909 demonstrated a laboratory process for synthesizing liquid ammonia directly from nitrogen and hydrogen gas under high pressure over a metal catalyst, solving the nitrogen-fixation problem that had limited how much fertilizer could be produced from mined or manufactured nitrogen compounds. Carl Bosch led the engineering effort that scaled the reaction to industrial production at BASF, and the combined Haber-Bosch process is credited by common estimates with sustaining roughly half of current world population through fertilizer nitrogen that natural sources could not have supplied. Haber received the 1918 Nobel Prize in Chemistry for the ammonia synthesis, awarded in 1919 amid protest from Allied scientists over his separate wartime role: as head of Germany's chemical warfare effort he personally directed the first large-scale chlorine gas attack of the First World War, at the Second Battle of Ypres on 22 April 1915, and continued to direct German gas-weapons research afterward. His first wife Clara Immerwahr, also a chemist, died on 2 May 1915 of a gunshot wound, days after he returned from directing the Ypres attack; the documented facts of her death and the historians' dispute over her reasons are recorded on her own entry. Haber left Germany in 1933 after Nazi civil service laws forced the dismissal of Jewish employees, including scientists he had personally recruited to his own institute, and died in Switzerland in January 1934.