Photographic Emulsion Grains with Cores: Part I. Evidence for the Presence of Cores*

Neutral iodobromide emulsions made by the addition of silver nitrate to alkali halides in gelatin may, under certain conditions, contain a proportion of grains with cores of iodobromide phases. The maximum iodide contents (i) of these cores are related to the precipitation temperature (T) by the empirical equation i= 34.5+0.165(T–25). Grains containing such cores show very regular print-out distribution.