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THE PHOTO-MINIATURE greater rapidity and softer contrasts. Sodium sulphite has a marked influence in hydroquinone development; the greater the proportion of sulphite employed in a given formula, the stronger will be the contrasts in the negative. Potassium bromide acts as a powerful restrainer with hydroquinone, and is therefore sparingly used, e. g. 3 to s drops of a IO per cent solution in 4 ounces of developer for normal exposures; IO to 30 drops in cases of overexposure or with soft working plates. Citric acid and yellow prussiate of potash are alternate restrainers. . . A satisfactory single-solution hydroSmgle-Solution quinone developer may be made up as Formula follows: Water (hot), IS ounces; hydroquinone, Uounce; sodium sulphite (cryst.), 4 ounces; potassium carbonate, 6 ounces; potassium bromide, I8 grains. Dilute with from 4 to 6 times its bulk of water for normal use. . Cramer's two-solution developer is Tw;~~~on as follows: No. r-Distilled water (hot), 2S ounces; sodium sulphite (cryst.) 3 ounces; hydroquinone (Hauff), Uou11ce; potassium bromide, 7(ounce. No. 2-Water, 25 ounces; sodium carbonate (cryst.), 6 ounces. For use, take equal parts of No. I and No. 2 at 6S째 Fahr. A typical two-solution formula for ForsJire!em lantern slide plates is as follows: No. I -Water (hot), 2oounces; hydroquinone, ISO grains; potass. metabisulphite, Io grains; potass. bromide, so grains. No. 2-Water, 20 ounces; sodium sulphite (cryst.), 2 ounces; sodium hydrate, IOO grains. For use take equal parts No. x and No. 2. For copies of line drawings, sketches, In Copying maps, etc., where extreme density combined with clear lines is required, the following formula will be found reliable: No. IWater (hot), 20 ounces; hydroquinone, x6o grains; sodium sulphite (cryst.), 4 ounces; citric acid, 6o grains; potass. bromide,. x6o grains. No. 2-Water, 20 ounces; potass. hydrate, 320 grains. For use take equal parts of No. I and No. 2, or, where overexposure is indicated. 2 parts No. t to 1 part No. 2. -

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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...