Metol- Adurol.

435. With advantage sometimes adurol takes the place of hydroquinone in combination with metol, and it has the advantage of working more clearly, and dissolving more easily, while its keeping properties are still greater. Concentrated solutions can therefore be made which are especially adapted for amateurs. Meto l -adurol works in a similar manner to metol - hydroquinone, and is very economical. It is equally as good a developer for paper as for plates, and is especially good for lantern plates. Metol - adurol in the combination given, in spite of its rapidity, can be easily controlled with bromide of potassium, and especially the used developer can be applied as advantageously for over-exposures. Metol - adurol is a good developer, which above all others best combines the advantages of a rapid developer with variation, and may therefore be recommended as a universal developer for studio work for those who do not care to use pyro.

Formula No. i. Metol - Adurol Two - Solution Developer.

436. The metol and adurol must be dissolved before the sulphite is added. For use prepare as follows : For rapid development take one part A, one part B. Duration of development two to three minutes. For slow development take one part A, one part B, one part of water, and add from five to ten drops bromide of potassium. Duration of development from three to four minutes. The temperature of the developer should not exceed sixty-eight degrees Fahr. Previously used developer can be repeatedly employed.

Formula No. 2. Metol - Adurol One - Solution Developer.

437. The metol and adurol must be dissolved before the sulphite is added. For use prepare as follows: For rapid development take one part solution to five parts water. Duration of development from two to three minutes. For slow development take one part solution, and fifteen parts water. Duration of development about five minutes.

438. Metol - adurol developer, on account of its small contents of metol and larger contents of adurol, is very easily variable. A few drops of bromide of potassium suffices to retard development. Where you have a plate of strong overexposure take a previously used developer with the further addition of bromide of potassium. A still better plan is to take less potash for the developer, in which case the influence of the bromide of potassium is strong. Take, for instance, for formula No. 1, forty parts A to ten parts B, fifty parts water, five parts bromide of potassium. For Formula No. 2, fifteen parts solution, eighty parts water, five parts bromide of potassium. Where over-exposure has not been so great the used developer suffices for development. For unknown exposure always commence with the used developer, and correct according to requirements.

For fixing use the acid-fixing bath, prepared as follows : -

WAVE ACTION Study No. 9, See Page 345 Hung at Third American Solon J. R. Peterson, Portland, Oregon.