A chloro-bromide emulsion contains a mixture of silver bromide and silver chloride. Papers coated with this (called chloro-bromide or C.B. papers) are slower than bromide but more rapid than gaslight papers, and are among the most beautiful media for the production of warm tones, giving a range of colours from warm or brownish black to rich brown. This range is obtained by adjusting the exposure time and developer, and such fine gradations result from individual adjustments that probably no two workers could produce identically the same results. The mastery of chloro-bromide printing is thus a fine art, and depends mainly on the tastes and capabilities of the individual.