ORTOL (Pr. and Ger., Ortol) Hauff's developer, containing orthomethylami dophenol, OH and hydroquinoni introduced from Germany in 1897 ; in charac ter, intermediate between metol and pyro-soda. It is a yellowish-white crystalline powder, very soluble in water, with which it forms a colourless solution which gives a blackish image. It will not work alone ; combined with sodium sulphite it works very slowly, some hours being required to produce an image ; but in conjunction with sodium or potassium carbonate it forms a steady working developer, with a factor of io. It is suitable for all dry plates, lantern plates, and bromide and gaslight papers. When properly used, it does not stain the negative, but when ammonia or acetone is used, or sulphite is added to the ortol solution, a reddish stain sometimes appears. The use of metabisulphite and of a carbonate, however, tends to prevent staining, but should it appear it may often be removed with methylated spirit.
Ortol may be used in a one- or, preferably, two-solution form : One-solution Ortol . . . 8o grs. g g.
Potass. metabisulphite 20 „ 2•25 „ Sodium sulphite . 2 OZ. I IO „ Potassium carbonate . 64o grs. 73 „ Potassium bromide . 4 „ •5 If Water . . . 20 oz. 1,00o ccs.
This is best made up as required, the ortol and metabisulphite being dissolved in one half of the water, the remainder of the chemicals in the other half, and the two solutions mixed together.
Two-solution A. Ortol . . 14o grs. 16 g. Potassium meta bisulphite . 7o „ 8 „Cold water . 20 OZ. 1,000 ccs.
B. Sodium carbonate 21 oz. 138 g.
Sodium sulphite . 21 „ ,, Water . . zo „ r,000 ccs.
Or B. Potass. carbonate 1 oz. 55 g.
Sodium sulphite . 21 „ ,, Water . . 20 „ 1,00o ccs.
Use equal parts of A and B.
If a restrainer is needed, add a few drops of a io per cent. solution of potassium bromide, or embody the bromide in the developer when making it by adding to either of the B solutions from 8 to 16 grs. per zo oz. (i to z g. per i,000 ccs.). A weak solution of " hypo " has been recom mended as a restrainer, but it needs to be used with great caution. A io per cent. solution of a caustic alkali may be used as an accelerator in cases of under-exposure. By increasing the proportion of A, harder negatives will be pro duced; and the converse also holds good. A lower temperature than 66° F. (19° C.) will retard development, and during very cold weather the potassium bromide may with advantage be omitted. The high lights of the image appear normally in from zo to 3o seconds, and then the half-tones and shadows, the density being added at the same time ; develop ment is usually complete in from four to five minutes.