Justus von Liebig. Portrait of Baron Justus von Liebig (1803-1873), German organic chemist. After receiving his doctorate, he became an assistant to the French chemist Gay-Lussac. In 1825 he became professor at the Giessen University, Germany, where he founded an influential teaching labora- tory and gained a reputation for his bitter argu- ments with other scientists. By 1830 he had devel- oped an accurate method of analysing organic compounds by examining the products generated when they were burnt in pure oxygen. Liebig recognised that carbohydrates and fat are the fuel" of the animal body. He suggested using potassium and phosphorus as fertilizers in agriculture."