On the Properties of Fog

Abstract

The kinetics of development observed in our laboratory showed that under the normal condition of chemical sensitization the emulsion: grains fall into two distinguishable classes according to their activity in initiating development. Fog centres are assumed to be catalytic centres which initiate direct development of the grains immediately. In the absence of catalytic centres the stiver nuclealion in developer occurs to form catalytic centres by solution physical development. A longer lime, therefore, is required to Inltlllie development of thiS kind of grains. The action of the oxidizing solution on the kinetics of fog development is investigated. The retardation of development of the grains carrying fog centres is attributed to the destruction of fog centres by oxidation. The reason for the acceleration of development of grains carrying sensitivity centres is supposed to be the weakening of the protection of gelatin by oxidation, after the sensitivity centres being destructed.