Martin Klaproth was a German chemist noted for his pioneering work in chemical analysis. He discovered the elements zirconium (1789) and uranium (in fact, uranium oxide: 1789), and rediscovered and named titanium (1795), tellurium (1798), and cerium (1803), some of which had already been isolated, although left unnamed, by other scientists. Klaproth began as an apothecary's assistant and became the first professor of chemistry at Berlin University.