Paper developers brown-tone

Many toning processes in photography involve the use of selenium compounds.6 One such process recently recommended consists in treating the print or lantern slide, after developing, fixing and washing, with a solution containing about 1 per cent, of crystalline sodium sulphide and 1 per cent, of sodium selenite or selenious acid after twenty minutes or so in such a bath intense brown tones are obtained with chlorobromide papers, or brown-violet tones with pure bromide papers.7... 

Without dilution this developer will produce brown-black tones on papers in about 2 minutes. Diluted 1 2, this developer produces brown tones in 4-8 minutes. Diluting 1 4, and developing 8 to 15 minutes, produces a red-brown tone. Diluting 1 6, and developing from 15 to 25 minutes, will produce a red tone. For still warmer tones, add 10.0 grams of sodium bicarbonate to each liter of the diluted developer. 

This developer will produce a variety of brown to warm black tones on various papers, depending on dilution and exposure time. 

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