GMELIN, the name of a family of German scientists. First of any consequence was Johann Georg Gmelin (1674-1728), apothecary and chemist of distinction. Of greater fame was Leo pold Gmelin (1788-1855) great-grandson of Johann Georg. Leo pold studied medicine and chemistry at Gottingen, Tubingen, and Vienna, and in 1813 began to lecture on chemistry at Heidelberg, where he subsequently became a professor in chemistry and medi cine. He is remembered for his discovery of potassium ferrocya nide in 1822 and for his important Handbuch der Chemie (1st ed. 1817-19, 4th ed. 1843-55). He resigned his chair in 1852 and died the following year. His father's cousin, Christian Gottlob Gmelin (1792--186o), was one of the first to devise a process for the artificial manufacture of ultramarine (1828) ; he also observed the red colouration given to a flame by lithium salts.