Haber’s father was a dye manufacturer and so he studied organic chemistry to prepare him for the family firm. However, physical chemistry interested him more, and he worked on flames and on electrochemistry. By 1911 he was well known and was made director of the new Kaiser Wilhelm Institute for Physical Chemistry at Berlin–Dahlem. From about 1900 he worked on the problem of ammonia synthesis. Crookes had shown that, if the world continued to rely on Chilean nitrate deposits to provide nitrogenous fertilizer for agriculture, famine was inevitable. Haber solved the problem by 1908, showing that nitrogen from air could be used to make ammonia; the reaction N2 + 3H2⇔2NH3 could be used at c. 400°C under pressure with a modified iron catalyst. With C Bosch (1874 - 1940) to develop the process to an industrial scale, production was established by 1913; the Haber–Bosch process made about 108 tonnes of ammonia annually by the 1980s. About 80% of this is used to make fertilizers. In the First World War it also solved the problem of making explosives for Germany, since nitric acid (essential for their production) can be made by oxidizing ammonia. Haber was also in scientific control of Germany’s chemical warfare and devised gas masks and other defence against the Allies’ gas warfare. A Nobel Prize was awarded to him in 1918 for the ammonia synthesis.