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the formula CsH.(OH)t + CsH.OHNHCH.-- H,:o, Roylon is a similar mixture, used as an equivalent and giving identical results. Ortol comes as a coarse, yellowish, Characteristic:a crystalline powder, very soluble in water. As a developer it stands between pyro and the familiar metol-hydroquinone combination. In its dry state it oxidizes readily, but may be kept unchanged for years in well-stoppered, orangecolored bottles. In solution with potassium metabisulphite it retains its power and keeps well, colorless, for many months. It gains in developing power in combination with alkaline sulphites and sodium carbonate, and is very sensitive to the retarding action of potassium bromide, which makes it readily controllable for plates which have been overexposed. It has no injurious action on the hands, and gives a brown-black image of fine grain. It can be used as a universal developer, by modification, for plates, films and papers or for lantern slides, and can be combined with hydroquinone. A favorite two-solution developer for Formulas plates or films is: No. x-Water, 20 ounces; potass. metabisulphite, so grains; ortol, 100 grains. No. 2--Water, 20 ounces; sodium carbonate (cryst.), 2 ounces; sodium sulphite {cryst.), 2 ounces. For use, take equal parts Nos. I and 2 and water, with 2 to s drops of a 10 per cent solution of potass. bromide for each ounce of mixed developer. Single A good sin~e solution developer for Solution plates o.r films 1s: 'Yater, 8 to 12 ounces (according to subJect and exposure); ortol, 12 grains; potass. metabisulphite, 6 grains; sodium sulphite {cryst.), 120 grains; potass. carbonate (cryst.), so grains; potass. ferrocyanide (cryst.), 20 grains. Potassium bromide is not needed with this formula, the ferrocyanide retarding development slightly, giving clearness and vigor. T For tank development {plates) where Devel~ent widely ÂŤ?fferent exposures have to be dealt With, take: Water, 20 ounces; potass. metabisulphite, 5 grains; ortol, 10 grains;

Modern Photographic Developers  

A Practical Handbook to the New Developers Telling What They Are and How to Use Them with Reliable Formulae by The Photo Miniature, January...