Page 32

THE PHOTo-MINIATURE one hydrogen atom of the amido (NHt) group by a methyl (CHa) group, and is supplied commercially as a sulphate salt. From this it would seem to be a simple matter to make metol by taking paramidophenol, "methylating" it by the introduction of the methyl (CHa) group by any of the several chemical methods, and then sulphonating it. But in fact the process is not as simple as it seems, and the resulting methylatedparamidophenol-sulphate is not metol. Paul, stating that metol cannot be made by direct methylation, suggests an indirect method, viz., by heating parahydroglycine (of which the d~veloper glycin is the hydrochloric salt) up to its melting point (247°C.), when it decomposes into carbonic acid and metol (base) which, after sulphonation, yields the metol of commerce. Be this as it may, the only actual J~~!n•s reproduction of German metol which has as yet appeared is the product introduced by Johnson and Sons, London, in August, 1917, as a "British-made, pure metol (monomethylparamidophenol-sulphate). This, it is claimed, is absolutely identical with German metol in chemical composition, constitution, and behavior. It is now obtainable, in limited quantities, in this country. In everyday practical tests it is indistinguishable from German metol, although in appearance it is not as white, and oxidizes more readily than the German product. Inasmuch as the makers of Metol-Johnsons advise the use of their product in exactly the same proportions as are given in all standard and published metol formulas, where it is used alone, or in combination with hydroquinone or pyro, for plates, films, bromide and development papers, it is unnecessary to publish any specific formulas here. With this exception, we have had Swill occasional supplies of a developer said Metol to be "veritable metol" and not a substitute, imported from Switzerland during the past year or two. This was sold here as "Swiss Metol" and as Monomethyl-Paramidophenol-Sulphate, "guaranteed to be the same chemically as the best German metol." It had the appearance of German metol 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...

Advertisement