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MODERN DEVELOPERS

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for tank development, films and papers, and to be much more energetic than most metol substitutes. This is an American product of unWhartol known composition but said to possess "the forcing power of metol, is easier to control and does not fog as quickly." It is used in equivalent amount to replace metol in any metol formula, with the caution that Whartol needs only onethird the amount of potassium bromide generally used with metol. These claims indicate that it is either paramidophenol-hydrochloride or paramidophenolsulphate-plain or methylated. A developer of the same general Tarcole class as the above, i.e. either the sulphate or hydrochloride form of paramidophenol, is offered by a Cleveland, Ohio, firm as possessing good qualities. It is an American product and is said to be equally suitable for all classes of photographic work. I have not had an opportunity to test its working qualities, and the only announcement of it which has appeared tells nothing of its chemical composition or of formulas for use. Under this name Johnson & Sons, a Scalol few years ago, introduced a developer intended to replace metol, used in combination with hydroquinone or pyro. Its chemical composition was not divulged, but from its characteristic behavior and results it was probably either the hydrochloride or sulphate salt of paramidophenol. It would seem to have been superseded by the same makers' Metol-Johnsons. By replacing two hydrogen (H) atoms D . "d h 1 1llDI1 op eno-路 th 路 路 路 p henol hydrochloride m e orth o andpara positions m [Amidol] (Fig. 5, page 420) by two amido (NHt) -oH groups, Hauff, in 1892, obtained di/ ) -NII, amidophenol, the hydrochloride salt of which, CeHaOH(NHt)r-2HCl, was -2HCI later introduced commercially by Hauff 'and Andresen under the trade name -NH Amidol. Dianol (Lumiere), Nerol ' (Schering), Amidol-Johnson, and Acrol (Eastman) are chemically identical products. It is

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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...

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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