German naturalist, banker, and writer; born in Berlin Sept. 29, 1867; educated at the universities of Berlin (M. D. 1889) and Strasburg. In 1891 he entered as scientific assistant the service of a joint-stock company in the aluminum industry at Neuhausen, Switzerland. There he worked out, together with the director Kiliani, a method for the electrolytic production of chlorin and alkalis. To turn this invention to account he founded the electrochemical works at Bitterfeld in 1893, the first German undertaking in connection with electrochemical processes exclusively. While he was director of this company and of the electrochemical works established two years later at Rheinfeld, he devised electrolytic and electrothermic methods for producing natrium, magnesium, carbid, ferrosilicium, etc., details of which may be found in the corresponding patentwrits.
In 1899 Rathenau entered the board of directors of the Allgemeine Elektricitäts-Geseilschaft, which position he resigned in 1902 to become manager of the Berlin Handels-Gesellschaft, one of the oldest banking-houses in Germany. In 1902 he published a collection of essays under the title "Impressionen."