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THE PHOTO-MINIATURE Also, paramidophenol-sulphate precipitates paramidophenol (base) in sodium sulphite and carbonate solutions, which robs the solution of developing power and so "slows up" its action. This is clearly seen iQ. the repeated or long-continued use of such a developer. But by the addition of a small amount of sodium hydrate (caustic soda) the "speed" of the developer can be readily brought up to the metol standard, and by the occasional further addition of sodium hydrate in small amounts, this speed and developing power can be so completely maintained that, with this modification, paramidophenol-sulphate will develop as rapidly and go as far as metol, and probably farther than paramidophenol-hydrochloride. This point was given special emphasis in the literature introducing Kathol-a paramidophenol-sulphate developer of the best sort. Photographers, however, cling to an old-time prejudice against the use of caustic alkalies, and prejudice-is prejudice I It is now known that the peculiar advantages sought to be gained by the use of caustic soda with paramidophenol-sulphate are equally well secured by methylating the paramidophenol during its manufacture, so that the use of caustic soda can be eliminated and an energetic, speedy, and lasting developer made up with alkaline carbonates. For which reason it is probable that paramidophenol-sulphate will soon be generally replaced (commercially) by methylated paramidophenol-sulphate. In use paramidophenol-sulphate is C~cteristics invariably combined with hydroquinone mUse whether for plates, films, 路or papers. It' is a clean, rapid-working developer, giving detail quickly and building up density more slowly. With some brands the use of sodium hydrate is suggested as a means of controlling the speed of or reenergizing the developing solution when it seems to "slow down," but other makes claim that "no caustic soda is required" in their use. In the latter case one may surmise that they are either "methylated" products, or the hydrochloride salt in disguise, or simply high-grade paramidophenol-sulphate with its characteristic virtues and shortcomings. Given a well-balanced formula and

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...

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