Abstract
Radiotracer studies of the decomposition of thiosulphate during chemical sensitization show that only a minor proportion of the sensitizer has decomposed at optimum sensitivity, and yet more than this minimum quantity of sensitizer is required to be present in order to obtain the highest sensitivity. Moreover, the presence of stabilizers during the decomposition does not radically change the kinetics. Evidence for the displacement of thiosulphate from grains by addition of stabilizers is given.