A Latvian-born German physical chemist noted for his work on chemical reactions and electrolytes. Having studied chemistry and physics in Riga, he was appointed professor of chemistry at Riga in 1881. Six years later he accepted the then only chair in physical chemistry in Germany at the University of Leipzig. He retired in 1906 having been appointed as the first German exchange professor to Harvard. He was awarded the Nobel Prize for Chemistry in 1909 for his work on catalysis, chemical equilibria, and reaction velocities.