Karl Gnstav Bischof, a German chemist and geologist, born at Word, a suburb of Nuremberg, Jan. 18, 1792, died in Bonn, Nov. 30, 1870. He studied at Erlangen, devoting himself at first to mathematics and astronomy, but soon turned his whole attention to chemistry and the physical sciences. In 1822 he became professor of chemistry at Bonn, and remained such for almost half a century. His principal works are: Lehrbuch der Chemie (1816); Lehrbuch der Stochiometrie (1819); Entwickelung der Pflanzensubstanz (1819); Lehrbuch der rei-nen Chemie (1824); Die rullcanischen Mineral-quellen Deutschlands iind Frankreichs (1826); Die Wdrmelehre des Innern imsers Erdkorpers (1837); "Physical, Chemical, and Geological Researches on the Internal Heat of the Globe," written in English (Londjon, 1841). His great work, however, is the Lehrbuch der chemischen und physilalischen Geologie (2 vols., 1847-'54, enlarged and revised in 1863; English translation by Paul and Drummond, 1854-'9). His essay Des moyens de soustraire l'exploitation des mines de houille aux dangers d' explosions (1840) gained the prize among 14 competitors, offered by the academy at Brussels.