抄録
An automatic apparatus for the direct indication of the average particle size of powder has been designed and subjected to practical tests. It consists of a device for determining the average particle size of powder from air-permeability as deduced through Kozeny-Carman's equation when the sample is formed into a compact bed, The design for the apparatus here described is based on the author's previous method, but with the addition of the automatic calculating circuit, so that the particle size of the sample as to surface average diameter may be indicated on the meter directly, in microns. The measuring range of particle size is from 50 microns to 0.5 micron. The measurement is rapid, simple and reproducible. The results obtained by this apparatus was compared with that measured by other methods.