The Influence of Silver Halide Solvents In the Developer on the Characteristic Curve In Negative and Reversal Development

When a negative is developed in the presence of silver halide solvents, certain properties of the reversal blackening curve are found, all of which can be explained by a mechanism taking into account a physical development on already chemically developed silver. It is proved experimentally that such physical development takes place, and that the covering power of the already chemically developed silver does not increase in practice. Thiocyanate ions have a catalytic accelerating effect on the complex solution of silver halide which is necessary for physical development. Theoretical treatment of the kinetics of physical development on chemically developed silver leads to a differential equation, the solution of which is in agreement with the experiments. Under certain conditions the negative and reversal characteristic curves can be calculated theoretically from a given grain size distribution, taking into account physical development. The theoretical results are in complete agreement with the experimentally known phenomena.