A New Coulter Counter* for Particle Size Analysis in the Sieve Range

The Coulter Counter@, recognized in 1956 as a valuable instrument for accurate fast blood cell counting Cl], was almost immediately put to use for industrial particle counting applications [2 41. It proved itself to be fast and precise for measuring particle concentrations and particle size distributions. The fields of use increased as improvements appeared. In most applications the useful size range was from 0.4 200 WI-I diameter. Data accumulation is so fast that dynamic particulate systems such as crystal growth or dissolving rates of particles can be studied with a minimum of effect. The major improvements contributing to the instrument value are: