Investigations on the Influence of Gelatin on the Recrystallization of Silver Bromide Suspensions

Paper to be presented at a symposium on “Photographic Gelatin” being organized by the Science Committee of the Royal Photographic Society on 19-22 September 1967 in Cambridge.

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* During the printing of this issue we have learned with regret of the sudden death of Prof. W. Römer. Ed.

Abstract

The recrystallization rate of unprotected and gelatin protected AgBr suspensions was investigated in a wide range of KBr and NH₃ as well as AgNO₃ and NH₃ concentrations. The turbidimetric method was employed. The time required to attain a constant specular density in the initial part of the turbidimetric curve was adopted for describing the recrystallization rate. The ratio of the rates in gelatin and in water was called the recrystallization restraining factor. This factor is very much influenced by the concentration of ions present. It is highest at Ag—Br equilibrium and decreases considerably in the presence of Br or [AgfNH₃)₃]⁺ ions in excess. In the former case with non-restraining gelatins it approaches unity at the Br concentration of 3×10^–2 showing that gelatin molecules do not affect the recrystallization rate, and in these conditions recrystallization restraining action is due to the microcomponents only. Near the Ag—Br equilibrium the gelatin molecules probably affect considerably the recrystallization rate. Examination of the recrystallization curves shows that in case of restraining activity the recrystallization rate is slowed down with the progress of time.

Notes

Paper to be presented at a symposium on “Photographic Gelatin” being organized by the Science Committee of the Royal Photographic Society on 19-22 September 1967 in Cambridge.

* During the printing of this issue we have learned with regret of the sudden death of Prof. W. Römer. Ed.