Ernst Julius Cohen, 1869-1944

Abstract

Amongst the distinguished Dutch men of science of the generation that is now passing, or has already passed, away, a very high place must, by universal consent, be assigned to the subject of this memoir. It would be no exaggeration to say that the name, and very often the personality, of Ernst Cohen have been known to students of chemistry and physics throughout the world for nearly fifty years. His famous researches in the fields of polymorphism, electrochemistry, thermochemistry and piezochemistry, the excellent books he wrote, his many visits to other countries and the lectures he gave therein, and—last, but not least—the important part he played in the national and international organization and development of chemical science made Ernst Cohen one of the most outstanding and well beloved men of science of his day and generation. He was the devoted pupil and disciple of the great van’t Hoff, and belonged to that famous Dutch school of physico-chemical science associated with the names of van’t Hoff, Roozeboom, Cohen and Schreinemakers. Although van’t Hoff is, perhaps, best known to students of chemistry for his pioneer work on optical activity and the ‘tetrahedral carbon atom’, the laws of osmotic pressure and the application of thermodynamics to the study of chemical equilibria and ‘chemical dynamics’, he became interested in the conditions of formation and decomposition of double salts before he left Amsterdam, and during his Berlin period (from 1895 onwards) devoted himself to the study of the formation of oceanic salt denosits. The famous work of Roozeboom on ‘Heterogene Gleichgewichte’ is well known to physical chemists and metallurgists, whilst Schreinemakers, the mathematician and geometer, became the great investigator and exponent of ‘geometrical’ thermodynamics as applied to the transformation and equilibria of heterogeneous multicomponent systems.