Eilhard Mitsciierlich, a German chemist, born at Keuende, near Jever, grand duchy of Oldenburg, Jan. 7, 1794, died in Berlin, Aug. 28,1863. He was the son of a clergyman, and studied at the gymnasium of Jever, where Schlosser instructed him in oriental history and philology. He pursued his studies especially in this department at Paris, Heidelberg, and Gottingen, where he published Mirchondi Historia Thalicridarum (1815); and in 1818 he went to Berlin to study chemistry. He discovered the law of isomorphism, for which he received the medal of the royal society of London. At the invitation of Berzelius he accompanied him to Stockholm in 1819, and passed two years in his laboratory. On his return to Berlin, he succeeded Klaproth in the academy of sciences and in the chair of chemistry. His first results in the discovery of isomorphism were presented to the Berlin academy in 1819, and next year they were generally accepted. Its doctrine was developed by him in a long series of observations. In 1823 he completed the theory by the discovery that some substances, as sulphur and carbon, under different circumstances, crystallize in two dissimilar forms. Such bodies are termed dimorphous.
The reports of his investigations and discoveries are chiefly con-tained in a large number of papers in the journals of the Berlin academy and in the Annalen of Poggendorff. He also published Lehrbuch der Chemie (Berlin, 1829-40; 5th ed., 1853 et seq) He perfected the instruments for measuring the angles of crystals, and extended bis researches to the influence of heat on crystallization. Many instruments of his invention have been adopted in Germany and other countries, lie was one of the few foreign associates of the French institute. His posthumous work Ueber die mtlkanischen Er-scheinungen in der Elf el und -liber die Meta-morphie der Gesteine durch erhuhte Tempera-tur. edited by J. Roth, was published in Berlin in 1865. See Rose's Geduchtnissrede (Berlin, 1864). - His brother, Karl Gustav (born Nov. 9, 1805, died March 16, 1871), was professor of medicine at the university of Berlin. His principal work is Lehrbuch der Arzneimittel-MreiS vols., Berlin, 1847-'61).