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148 THE PHOTOGRAPHIC NEWS. [February 20, 1891. PHOTOGRAPHY IN AUSTRIA. Professor LAINER on Developers. Some years ago Professor Dr. Eder delivered some inte resting lectures at the Vienna Photographic Society. In one of them that excellent scientist, speaking on the future of photography, remarked that the next important im provements were probably to be expected in the dis covery of new developers. And, indeed, in a short time followed the hydroxylamine developer, suitable, however, only for developing silver bromide and gelatine papers, especially for enlargements. But after this came the hydro quinone and the eikonogen developers, which to-day have been brought to an incredible degree of perfection. One of the professors at the Governmental Lehr-und Versuchs- anstalt, named Alexander Lainer, has now published very far-reaching investigations, which I give here at length (after the Photographischen Correspondenz). Comparative studies of the developers at present known have shown that their final effect is pretty much the same, and that the chief difference is to be sought only in the duration of the development. For instantaneous photo graphs it is particularly important to possess quick-working developers, in order to register feeble impressions of light, with a sufficient thickness of reduction of silver. For portraits, it is desirable to carry out all chemical operations quickly, and in general one wishes also the dark parts to be rich in detail. To obtain these ends, different materials have been used, but without such a marked success being obtained with any one as to lead to the ex clusive introduction of one developer. Two years ago I called attention to the beneficial influence of ferrocyanide of potassium in the pyrogallol developer, and emphasised the fact that its addition is to be recommended particu larly for short exposures, and that dense negatives, full of contrasts, can be obtained with it. Captain llimly studied the effect of ferrocyanide of potassium on the hydroquinone developer, and came to the conclusion that the addition of some drops of a 30 per cent, solution of ferrocyanide of potassium is to be recommended in order to obtain more contrast. With it one achieves more than by an addition of potassium bromide, but yet without a restraining of the development such as takes place with the latter. Lately I have occupied myself much with the hydro quinone developer, with the addition of hydroxide of potassium and sodium hydroxide, instead of carbonates, and after many experiments obtained proportions which reduce very powerfully without the addition of ferro cyanide of potassium. In rapidity it surpasses all other hydroquinone developers. Recipe I. Solution A. Hydroquinone ... ... 10 grammes Neutral sulphite of sodium.. 25 ,, Water ... 60 cubic centimetres (cm. 3 ) Solution B. Caustic potash ... ... 50 grammes Water 100 cm. 3 Mix per cabinet plate— A (Recipe I) ... ... 60 cm. 3 B (Caustic potash) ... 3 cm. 3 This developer brought out a sensitomer image in 3 -minute to 24°, the negative quite clear. The image appears after about three seconds. It is not every kind of plate which allows the use of this developer, for in many sorts it pro duces a grey fog, an observation made by Eder and Lenhard with their potash hydroquinone developer. To the foregoing developer I added about 12 per cent, of ferrocyanide of potassium, and therewith achieved sharp ness with those kinds of plates which, without the ferro cyanide of potassium, showed fog ; yet the negatives were hard comparatively, the lights very dense. Changes in the proportions of the mixture led to a developer which is unequalled in its action. This developer, in rapidity of effect, surpasses also the French developer “ cristallos.” Recipe II. Solution A. Water ... ... ... ... ... 900 cm. 3 Sodium sulphite 40 grammes Ferrocyanide of potassium ... ... 120 „ Hydroquinone ... ... ... ... 10 ,, Solution B remains the same, namely, potassic hydrate 142. For use mix per cabinet plate. A (Recipe I) ... ... ... ... 60 cm. 3 B (Caustic potash 1 • 2)... ... ... 6 cm. 3 The image appears in about three seconds, and the development is finished in thirty to forty-five seconds, but then the fifth batch of sensitometer plates shows a vigour otherwise often exhibited only by the fourth; No. 25 was still recognisable with certainty. The fourth batch was surprisingly vigorous, and the first numbers showed a good density, without being opaque; the gradation was excellent. This developer distinguished itself by permitting the exposure to be shortened, by yielding details excellently clear in the shadows, and by allowing very rapid development. Of course plates considerably over-exposed must not be treated with any rapid developer. If one adds a larger quantity of caustic potash, the density of the negatives is diminished by the same length of exposure. A diminution of the hydro quinone, and an increase of the sodium sulphite, have a similar effect, which exactly determines the manner in which the ingredients act. A good recipe is that of using less ferrocyanide of potassium, and substituting sodium hydrate for caustic potash. Recipe III. Solution A. Water ... ... ... 950 c.m. 3 Sodium sulphite ... ... 30 grammes Ferrocyanide of potassium ... 90 23 Hydroquinone Solution B. 10 33 Sodium hydrate ... ••• ••• 30 grammes Water ... ... ••• ... 90 c.m. 3 If one mixes 60 cm. 3 A and 6 cm. 3 B (caustic potash 1-5-2), one obtains similar results as with Recipe 2; but if one mixes— A. (Recipe III) ... 60 c.m. 3 (1.) Natrium hydric, depur. B 1 . (Caustic soda 1:3) 12 c.m. 3 one has a modification of the rapid hydroquinone deve loper, which gives the negatives a softer character, and has a beautiful effect with many sorts of plates, while it produces quite clear negatives. Both Recipe II. and Recipe HL give quite rapid deve lopers, which, perhaps, bring out portraits too quickly for some practitioners. Tn that case I recommend Recipe IV., which admits of a somewhat slower, though still quite rapid development.