Size Distribution Analysis of Needle-Shaped Crystals

Two methods of measurement of the crystal size distribution of needle-shaped carystals are compared: direct measurement of a number of crystals on a microphotograph, which is rather tedious and time consuming, and the photosedimetric method which is quicker, easy to perform but not so suitable for not isometric crystals. A methods is described that brings results of both of these methods into agreement. The method has been verified on strongly anisometric particles of calcium sulphate.