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See also:MARIGNAC, See also:JEAN See also:CHARLES GALISSARD DE (1817-1894) , Swiss chemist, was See also:born at See also:Geneva on the 24th of See also:April 1817.
When sixteen years old he began to attend the Ecole Poly_ technique in See also:Paris, and from 1837 to 1839 studied at the Ecole See also:des Mines. Then, after a See also:short See also:- TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
- TIME, MEASUREMENT OF
- TIME, STANDARD
time in See also:Liebig's laboratory at See also:Giessen, and in the Sevres See also:porcelain factory, he became in 1841 See also:professor of See also:chemistry in the See also:academy of Geneva. In 1845 he was appointed professor of See also:mineralogy also, and held both chairs till 1878, when See also:ill-See also:health obliged him to resign. He died at Geneva on the 15th of April 1894. Marignac's name is well known for the careful and exact determinations of atomic weights which he carried out for twenty-eight of the elements. In undertaking this See also:work he had, like J. S. See also:Stas, the purpose of testing See also:Prout's See also:hypothesis, but he remained more disposed than the Belgian chemist to consider the possibility that it may have some degree of validity. Throughout his See also:life he paid See also:great See also:attention to the " rare earths " and the problem of separating and distinguishing them; in 1878 he extracted ytterbia from what was supposed to be pure erbia, and two years later found gadolinia and See also:samaria in the samarskite earths. In 1858 he pointed out the isomorphism of the fluostannates and the fluosilicates, thus settling the then vexed question of the See also:composition of silicic See also:acid; and subsequently he studied the fluosalts of See also:zirconium, See also:boron, See also:tungsten, &c., and prepared silicotungstic acid, one of the first examples of the complex inorganic acids. In See also:physical chemistry he carried out many researches on the nature and See also:process of See also:solution, investigating in particular the thermal effects produced by the dilution of saline solutions, the variation of the specific See also:heat of saline solutions with temperature and concentration, and the phenomena of liquid See also:diffusion.
A memorial lecture by P. T. Cleve, printed in the See also:Journal of the See also:London Chemical Society for 1895, contains a See also:list of Marignac's papers.
End of Article: MARIGNAC, JEAN CHARLES GALISSARD DE (1817-1894)
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