Abstract: There is described a particle size distribution analysis apparatus comprising an oscillatory assembly, the oscillatory assembly comprising a receptacle for receiving a powder sample and having an opening through which powder may be discharged, the opening being variable in size, and support means allowing the receptacle to reciprocate along an arcuate path, entry means for introducing the sample into the receptacle, adjusting means for varying the size of the opening, bias means to urge the oscillatory assembly towards a datum position, and drive means to induce oscillations of the oscillatory assembly. Detector means may be provided to determine a characteristic of the oscillations of the oscillatory assembly and hence determine the mass of powder remaining in the receptacle.