Direct observation of secondary nuclei production

Abstract

Production of secondary nuclei by low energy contacts between a crystal and a solid rod was investigated by direct microscopic observation. Crystal attrition occurred very easily and produced many secondary nuclei. Using both potash alum and magnesium sulphate heptahydrate growing in aqueous solution, large numbers of particles in the size range 1–10 μm were produced in both super- and undersaturated solutions. In addition larger pieces of crystalline material up to 50 μm in size were removed from the crystal under growing conditions. Many of the smaller particles grew very slowly in supersaturated solutions whereas the larger particles appeared to grow at rates characteristic of large crystals.