any of the photographic preparations consisting of substances suspended in colloidal binders. Emulsions are coated on supporting plates and dried; during processing, they swell when immersed in cold water but do not dissolve. Photosensitive emulsions contain microcrystals of silver halides (except AgF) and such other substances as diazo compounds and chromium salts. These compounds are uniformly dispersed, primarily in gelatin, but to a lesser extent in cellulose nitrates, albumin, polyvinyl alcohol, and other colloids. In addition to the dispersed compounds, photosensitive emulsions contain small quantities of such additives as optical sensitizers, hardeners, and stabilizers.