The Elon–Hydroquinone Developer–IV. Development by Elon and by Hydroquinone*

Elon and hydroquinone developers have been studied under conditions of varying concentration and pH. It was found that the rate of development by both agents varies as the first, or less, power of the concentration, thus indicating that the super-additivity of the Elon-hydroquinone developer is not a function of increasing developing agent concentration. The combined data for changing concentration and pH indicate that both the single and double charged hydroquinone ions are active.