Sedimentation of solid discs in viscous medium

Free sedimentation velocities of thin discs have been measured in castor oil and liquid paraffin at constant temperature. Wall and end corrections have been applied to the measured velocities and the corrected values have been compared with those calculated fromOverbeck andGans' equations. Sedimentation velocities have been measured in both edgewise and broadsideon positions. Good agreements have been obtained with the theory in both types of sedimentation. The broadsideon position has been found to be the preferred orientation and all particles deviating even slightly from the edgewise position take the preferred orientation quickly. Results of other investigators have been discussed in the light of the present findings.Based on a dissertation submitted by (1) in partial fulfilment of the requirements for M. Sc. degree of the Dacca University in 1961.