An optical method for mechanical analysis of soils, etc

The sedimentation method for the mechanical analysis of poly-disperse systems such as a suspension of soil in water is now in its various modifications a well-established technique of analysis(1). Unfortunately, they all, with one exception, involve interference of some kind with the process of sedimentation itself; either by the introduction of pipettes and hydrometers, or the opening of drain-cocks, and the one exception, viz. the sedimentation balance, is subject to a considerable error of a different kind (2). The present paper describes the results of attempts to use the transmission of a beam of light through a glass cell, as a measure of the sedimentation process taking place within it, the transmitted light being received on a photo-electric cell.