Johann Georg Forchhammer, a Danish geologist and chemist, born at Husum, Schleswig, July 26, 1794, died in Copenhagen, Dec. 13, 1865. He became secretary of Oersted, ac-companied him on a mineralogical expedition to the island of Bornholm (1818-'19), and subsequently made several journeys in Great Britain, France, and Denmark at the expense of the Danish government. He was professor of geology at Copenhagen, and in 1851 succeeded Oersted as secretary of the academy of sciences. His principal works are Dane-marks geognostiske Forhold (1835), and Skan-dinariens geognostiske Natur (1843). He also excelled as a lecturer on chemistry and mineralogy, and wrote a manual of universal chemistry {Laerebog i Stoffernes almindelige C/iemie, 1834-'5). '