German Ivanovich Gess

(Hess, Germaine Henri). Born July 26 (Aug. 7), 1802, in Geneva; died Nov. 30 (Dec. 12), 1850, in St. Petersburg. Russian chemist. Academician of the St. Petersburg Academy of Sciences (1830).

Gess was a professor at the St. Petersburg Mining Institute from 1832 to 1849. In 1840 he discovered the law of constant heat summation (Hess’ law). In 1842 he established the rule of thermoneutrality, according to which there is no loss of heat when mixing salt solutions. He also investigated (1831) the ability of finely crushed platinum to catalyze the reaction of oxygen with hydrogen and to adsorb hydrogen. He discovered several new minerals. Gess also studied the action of hot air blasts when smelting pig iron in blast furnaces.