Marignac, Jean Charles Galissard de

Born Apr. 24, 1817, in Geneva; died there Apr. 16, 1894. Swiss chemist. Member of the Paris Academy of Sciences (1886).

Marignac graduated from the School of Mines in Paris in 1839. He held a professorship at the University of Geneva from 1841 to 1878. Between 1842 and 1883, Marignac determined the atomic weights of 29 elements, thereby verifying Prout’s hypothesis. In 1866 he developed a method of separating niobium and tantalum. He discovered ytterbium oxide in 1878, and in 1880, the oxide of an unknown rare-earth element (named gadolinium oxide in 1886).