This article contains information on Einstein's experimental work. It pays main attention to three of his studies (1915--1916) aimed at experimental demonstration of Ampere molecular currents. It treats the content of these studies, their prehistory, and the peculiar revaluation of their results after the discovery of the spin of the electron. It traces the effect of these studies on Einstein's attitude toward the Stern--Gerlach experiments and the studies of Uhlenbeck and Goudsmit, and also points out their genetic tie with the well-known work of Einstein and Ehrenfest.