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Abstract
Several derivatives of 7, 8-dihydroxybenzopyrylium chloride and of 7, 8-dihydroxycoumarin (daphne- tin) were synthesized and investigated as developing agents. They function best in the pH range 10-11, and possess similar photographic properties to pyrogallol, but show better keeping properties in solution. The best compounds are daphnetin, its 3-methyl derivative and its 3, 4-dimethyl derivative. These give higher speed for the same contrast than do catechol or metol.