Fritz Haber

Fritz Haber fed the world and invented chemical warfare. Born in Breslau in 1868 into a Jewish family, he converted to Lutheranism as a young man, which was the ordinary price of an academic career in imperial Germany, and became a professor at Karlsruhe. The problem he solved was nitrogen. Plants need fixed nitrogen and the supply came from Chilean nitrate deposits and guano, both finite; the chemist William Crookes had warned in 1898 that the world faced famine. The atmosphere is four-fifths nitrogen, but the molecule is almost inert. Between 1905 and 1909 Haber found conditions — around 200 atmospheres, 400 to 500 degrees, an osmium and later iron catalyst — under which nitrogen and hydrogen combine into ammonia. Carl Bosch scaled it at BASF, and the Haber-Bosch process now supports something close to half the population alive. It also gave Germany explosives after the British blockade cut off Chilean nitrate, and extended the First World War by years. He then directed Germany's chemical weapons programme, personally supervising the first chlorine release at Ypres in April 1915 and arguing that gas would shorten the war. His wife Clara, herself a chemist, shot herself with his service pistol days later. He received the 1918 Nobel Prize amid international protest. He spent the 1920s trying to extract gold from seawater to pay reparations, and failed. The Nazis forced him out in 1933 despite his conversion and his service. He died in Basel in 1934. Zyklon B was developed from work done in his institute.

• Lived: 1868 CE – 1934 CE
• Nationality: German
• Roles: chemist, scientist