Habit Changes in Mixed Crystals of Phenazine and N-Oxyphenazine

Abstract

WE recently measured and plotted against composition¹ the refractive indices of a complete mixed crystal series of phenazine and N-oxyphenazine, crystallized from methyl ethyl ketone. We originally thought that the crystals, which were tabular, showed the same habit, the best-developed faces being (&2bar;01), but we have since found this to be a mistake. A more careful study of the morphology, using X-ray oscillation photographs, has shown that the {hol} habit does actually change across the series (Fig. 1). Although the relative sizes of the crystal faces vary in the series, the tabular appearance is obtained at all concentrations, except in a region of poor development.