DOCUMENT 139 APRIL 1902 337 "On the Thermodynamic Theory of the Difference in Potentials between Metals and Fully Dissociated Solutions of Their Salts and on an Electrical Method for Investigating Molecular Forces" [April 1902. Text in Volume 2] 139. To Conrad Habicht [Bern, April? 1902][1] Lieber Habicht! Ehrat[2] jammert mich per Postkarte an, daß er von Ihnen "Archimedis opera" nicht zurückkriegen kann. Er muß es unbedingt Montag abgeben, ansonst er von seinem Meister und Herrn R[udio][3] hochdeutsch ange- brummt wird. Also gleich zur Post! Auf vergnügliches W. Ihr E. AKS (Prof. Walter Habicht, Rodersdorf). The verso is addressed "Herrn Conrad Habicht Wieylerstr. Bern Breitenrain." [1] Dated by the references to Archimedes' works and to Rudio (see note 3). [2] Jakob Ehrat was Assistent to Professor Ferdinand Rudio (1856-1929) of the ETH. [3] Rudio offered a course, "Geschichte des Problems von der Quadratur des Zirkels," which began 14 April (see ETH Programm 1902, pp. [3], 20). "Kinetic Theory of Thermal Equilibrium and of the Second Law of Thermodynamics" [June 1902. Text in Volume 2]