PHYSICAL RETARDATION BY MODIFIED GELATIN

The effect of the isoionic point of gelatin on physical ripening prope rties was studied by the physical retardance test using modified gelat ins. Carboxylic groups were blocked by the amidation reaction and amin o groups were blocked by the acylation reaction. Physical ripening spe ed decreased in relation to the ratio of blocked carboxylic groups and increased when the ratio of carboxylic groups increased due to acyl s ubstitution. However we found that the final particle size of silver h alide did not depend on the isoionic point of the gelatin. It was assu med that the charge shift in the gelatin molecules affected the physic al ripening speed and did not affect the final particle size.