On the “Colloidal Retentivity“ of Gelatin against Silver Halide

The term colloidal retentivity is introduced as a measure of the ripening characteristics of photographic gelatins and for describing the progress of the ripening of photographic emulsions. A diluted emulsion is allowed to sediment in a cell for a few minutes. The cell is then alternately illuminated from above and below the cell. The intensity of the light scattered in a horizontal plane when the cell is illuminated from above is defined as the colloidal retentivity. It is influenced by the more rapidly setting grains which attenuate the beam from below.