Electron microscopic studies on the coloration by X-rays (1), the additive colouration, and also the bleaching process (2) of some alkali-halide crystals were made only at room temperature until now. We also successively observed colouring and bleaching processes of the definite position of the same KCl crystal by using two-stage replicas (3). The same kind of observations at liquid air temperature, however, is more important physically and practicable, after the replica technique at liquid air temperature has been studied in the meantime (4).
Unable to display preview. Download preview PDF.