抄録
Crystal morphology and crystal habit of phenytoin crystals were studied by the immersion method using a polarizing microscope. Several kinds of phenytoin materials, which had been confirmed to be lying on the same orientation by measuring key refractive indices, were photographed under crossed polars. The relationship between the patterns of retardation colors and the shapes of the phenytoin crystals were analyzed quantitatively using the chart indicating the relation of thickness to retardation colors, and concurrently several necessary facial angles were measured. On the basis of these results as well as edge angles measured under a microscope a stereographic projection was drawn finally, and an orthorhombic symmetry, an axial ratio and some facial angles were determined. Several kinds of crystal habits observed from the photographs were drawn by the classic crystallographic habit drawing method using the stereographic projection.
