Estimation of Specific Surface of developed Silver by Thiosulphate Adsorption^*

* Communication No, 2029H from the Kodak Research Laboratories.

Abstract

By tracer methods it was demonstrated that thiosulphate is most tenaciously adsorbed to developed silver or silver foil. A limiting amount was held by any surface: one thiosulphate ion being estimated for every three silver atoms in the surface. On bleaching developed silver with acid dichromate, no decrease in radioactivity occurred, demonstrating quantitative formation of silver sulphide from adsorbed thiosulphate. On the basis of these observations, the silver sulphide content of bleached photographic images can be used to estimate the specific surface of the silver. Reasonable estimates were obtained of the particle size of a Carey-Lea silver sol. In agreement with earlier X-ray determinations, the mean filament diameters of developed silver from a series of emulsions did not increase much with increased undeveloped grain size.

Notes

* Communication No, 2029H from the Kodak Research Laboratories.