COHEN, ERNST JULIUS (1869— ), Dutch chemist, was born at Amsterdam on March 7, 1869. He studied chemistry under Arrhenius at Stockholm, Moissan at Paris, and Van t'Hoff at Amsterdam; he became assistant to the latter in the university chemical laboratories at Amsterdam in 1893 and in 1902 he was appointed professor of physical chemistry at the University of Utrecht.
Cohen's most important work is on the allotropy of metals, and particularly of tin; this was published mainly in the periods 1900-02 and 1911-12. He is the author of a large number of papers on physical and electrochemistry, and his piezo-chemical studies are important. His papers are published chiefly in the Dutch and German scientific journals.
Cohen has also written Studies in Chemical Dynamics after Van t'Hoff (1896), Physical Chemistry for Biologists, Inorganic Chemistry for Medical Students (1907), and Jacobus, Henricus Van t'Hoff, his Life and Work (1912) . Cohen is a foreign member of the Royal Society of London.