AbstractMixed crystals of AgBr with a few % of PbBr2and of AgCl with a few % of CdCl2were prepared, partly by co‐precipitation and partly from the melt. Debije‐Scherrer photographs showed no change in lattice parameter compared with the pure silver halides. That actually mixed crystals were formed was concluded from the marked decrease in photosensitivity (colouring on exposure to ultraviolet light) as compared to that of the pure hali