AbstractThe disintegration of silver halide crystals by irradiation with ultraviolet light manifests itself in Debije‐Scherrer photographs ofpowdered preparationsin various ways: by diminishing the discontinuous appearance of the interference lines of the non‐irradiated crystallites and by a broadening of the lines of the Kα1α2‐doublet, as shown by high‐order reflections. Also the formation of silver in a finely divided form is clearly visible.On irradiation ofsingle crystalsof silver chloride, the X‐ray photographs show the presence of silver crystallites with preferential orientations, as evident from the appearance of Debije‐interference lines with intensity maxima. This points to a formation of individual small silver crystallites with partly coinciding orientations. The exact crystallographic character of the preferred orientation and its possible connection with that of the irradiated AgCl‐crystal, has not be