Brownian Movement and Molecular Reality

Abstract

THIS small volume of ninety-three pages is a translation by Mr. F. Soddy, F.R.S., of a memoir published by Prof. J. Perrin in the Annales de Chimie et de Physique in September, 1909. In this paper, Prof. Perrin gave a detailed account of his work upon the distribution in fluids of small particles, which show the Brownian movement, and the bearing of these results on the kinetic theory of matter. An interesting survey is first given of the historical development cf this subject. The English naturalist, Brown, directed attention in 1827 to the fact that small particles suspended in liquids were always in a state of rapid but irregular movement. Comparatively little notice was paid to this observation until 1889, when Gouy showed that the Brownian movement could not be ascribed to temperature differences,but was a persistent effect which was probably a necessary consequence of the kinetic theory of matter. Since that time a large amount of interesting work has been done, especially by Continental workers, to throw further light on the magnitude and nature of the Brownian movement.