A new apparatus for recording particle size distribution

A manometer and sensitive capacitance transducer follow the drop in hydrostatic pressure at a point near the bottom of a column of soil suspension during sedimentation. Current from the transducer is fed to a recorder which traces an accumulation curve. The first derivative (slope of the curve) gives a summation curve of the particle size distributions. Results on four soils with different particle size distributions agree with those obtained by a standard pipette-sampling/sieving procedure over the range 20-200 microns effective settling diameter.