Comparative Study of the Sensitivity Specks Formed During the Ripening of Silver Chloride Relative to Silver Bromide with Gold-198 and Gold-198 Plus Sulphur-35*†

Abstract

AbstractBy means of radioactive tracers 35S and 198Au a comparative study of the composition of the sensitivity specks formed during the ripening of silver chloride and silver bromide emulsions with equal grain size (a = 0.2 //m) was made and related to their photographic response. The sensitizers used were gold chloride (198Au) and gold chloride combined with sodium thiosulphate (35Sext).A washing technique was required to differentiate between gold in a more or less soluble state adsorbed on the emulsion grains during ripening. A 10-4 M sodium sulphite solution was found to be useful. This gold-complexing solution was able to desorb gold ions from the grain surface, leaving undesorbed the presumed gold sulphide, silver gold sulphide, gold or gold oxide specks.The following conclusions could be drawn:(1) The ripening of silver chloride and silver bromide emulsions with gold chloride results in the formation of identical amounts of non-desorbable gold, but corresponding with higher fog values for the AgCI...