Ein einfaches Experiment zum Nachweis der Ampèreschen Molekularströme. Offprint

Einstein, Albert (1879-1955). Ein einfaches Experiment zum Nachweis der Ampèreschen Molekularströme. Offprint from Verhandlung der Deutschen Physikalischen Gesellschaft 18 (1916). 173-177pp. 230 x 157 mm. Original printed wrappers. Fine copy.

First Edition, Offprint Issue. In 1915 Einstein and Dutch physicist Wander Johannes de Haas conducted gyromagnetic experiments leading to the discovery of the Einstein-de Haas effect, which corresponds to the mechanical rotation induced in a ferromagnetic cylinder suspended inside a coil when an impulse of electric current is sent through the coil. Einstein was very enthusiastic about the experimental results, stating that he and de Haas had "given firm proof of the existence of Ampère's molecular currents" (quoted in Pais, Subtle is the Lord, pp. 245-246). After his collaboration with de Haas ended, Einstein published the present paper on the Einstein-de Haas effect, proposing a new experimental method for determining gyromagnetism. The Einstein-de Haas effect is now known to reveal a relationship between magnetism, angular momentum and electron spin; however, this was not understood at the time, as electron spin was not discovered until the 1920s. Weil, Albert Einstein Bibliography, 82.