1.1 ,This test method covers the determination of the particle size distribution of catalyst, catalyst carrier, and catalytic raw material particles and is one of several found valuable for the measurement of particle size. The range of average particle sizes investigated was from 1 to 300 μ,m equivalent spherical diameter. The technique is capable of measuring particles above and below this range. The angle and intensity of laser light scattered by the particles are selectively measured to permit calculation of a volume distribution using light-scattering techniques.