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THE PHOID-MINIATURE

temperature and has no tendency to fog. It is made up with either carbonate or caustic alkalies. A reliable formula is as follows: No. r A Formula -Water, IO ounces; pyrocatechin, 8o grains. No. 2-Water, IO ounces; tribasic sodium phosphate, I ounce; sodium sulphite (cryst.), 3 drams. For normal exposures take one part each of No. I and No. 2 and add one part water. (For a more vigorous, quick-working developer for normal exposures, increase the sodium salt in No. 2 by from so to IOO per cent.) For slight overexposure, take 2 parts No. I, I part No.2; for marked overexposure add to the above one-tenth part of IO per cent potass. bromide solution. For underexposure, take I part No. I, 2 parts No. 2 and add 3 parts of water, following, if necessary, by more of No. I to gain density. The restraining power of potass. bromide is small when carbonate alkalies are used, but increases when caustic alkalies or the tribasic sodium salt is employed. Pyrocatechin is the only developer E~~: which retains its normal developing power in the presence of "hypo," hence, in its modified forms of Elconal F and Kachin it was exploited for simultaneous development and fixing, but general experience failed to support the claims made for it in this particular. The most extravagant claims were made in behalf of Kachin as a developer when it was introduced in Britain, many experimentors averring that it possessed all the virtues and none of the defects of other developers, but it seems to have vanished so far from human ken that it is no longer "formularized" in the "B. J. Almanac," wherein it held place from I899 to I916. . A chemical combination of metol MQ~=~~e {base) and hydroquinone (CaRe ORNH) (CRah + CeRe (ORh, introduced by Lumii;re in I903 as an energetic developer used with or without an alkali. Sold in Britain as Quinomet. It is a fine, white powder, sparingly soluble in cold water, but freely soluble in hot water. A typical formula for time exposures is: Water (hot), 20 ounces; metoquinone, 86 grains; sodium sulphite (cryst.), 2U ounces.

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...

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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