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MODERN DEVELOPERS

431

Dissolve the ingredients in the order named. For the development of instantaneous exposures, add acetone, xU ounces, or one-third this quantity of sodium tribasic phosphate, or one-sixth the quantity of caustic lithia. This is Lumiere's formula. This, a condensation product of Pyramidol hydroquinone and paramidophenol, introduced by Hauberrisser a few years ago, is not now in the market. It had the formula C.H.OHNH-CeH. (OH2) H2SOt. In use it resembled paramidophenol, but offered special advantages for the correction of gross overexposure by its behavior with potassium bromide, yielding good negatives in overexposure ranging from sixteen to forty times normal. Adurol In the brief survey of the origins of -QH our modem developers already made., 'the reader has observed the changes or ( 1-Cl or Br modifications in developing properties effected by the introduction or substitution of such groups as OH and NHa ~H in various developer nuclei. The formation of para-dioxy-benzene or hydroquinone, seen in Fig. 8, page 421, is an illustration of such a change. In 1898 Hauff and Liippe Cramer independently investigated the possibilities of modifying hydroquinone by substituting a halogen (chlorine, bromine, etc.) for one of the hydrogen atoms in the hydroquinone nucleus. Their investigation resulted in the commercial introduction (1899) of two halogen derivatives of hydroquinone, both of which we know as the developer Adurol. As made by Hauff, Adurol is monochlor-hydroquinone, CeHa(OH)!Cl; as made by Schering it is monobrom-hydroquinone, C,H,(OHh Br. They are identical in general characteristics and behavior, although Lumiere and Seyewetz, in a later investigation (1914), found that the monobrom product wa.s more energetic than the monochlor form. Commercially Adurol is made by How Made passing bromine or chlorine into a solution of hydroquinone in benzene and evaporating to crystallization. It comes as a white, crystalline powder, readily soluble in water.

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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