Particle Size Analysis by Sedimentation.

Two methods of determining the size distribution of very fine powders by sedimentation in liquids are presented. Both methods result in a descriptive measure called the Stokesian diameter of the particles which is based on the terminal velocity of particles in fluids as predicted by Stokes law. One of the methods, gravity sedimentation using a recording balance, is useful in the nominal range of particle size of 5-100 microns. The second, photosedimentation, utilizes centrifugation to extend the range down to the area of 0.1 to 10 microns. Techniques of experimentation and methods of data reduction are discussed in detail for both methods. Complete computer programs for data analysis and sample outputs are included as appendices. Author