The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

Home | About | Photography | Contact






Bromide Paper
Heat to the boiling point, and add
Ferrous oxalate............500 grs.
Stir till dissolved, and bottle whilst warm. Some ferrous oxalate may precipitate out, but this will have but little effect upon the action of the developer, which is a saturated solution of ferrous oxalate. But the two latter methods were those first used, and have been gradually supplanted by the two-solution formula.
Ferrous Citro-Oxalate Developer. This modification of the oxalate developer was suggested by Abney in 1881, his original formula being: -
Neutral potassium citrate ... ...... 100 grs.
Ferrous oxalate ... ... ... ... 22 ,,
Distilled water         ...... ...... 1 oz.
The citrate of potassium is dissolved in the water by the aid of heat and the ferrous oxalate added, and the whole allowed to cool. A more convenient method, however, which Abney suggested in 1882 is to make two solutions as follows: -
No. i.
Potassium citrate Potassium oxalate Distilled water
No. 2
Ferrous sulphate Distilled water
The solutions are mixed in equal proportions just before using. The citro-oxalate developer does not require any addition of bromide as restrainer, its action not being quite so energetic as the ordinary oxalate, but it gives a fine velvety black deposit with most papers. Further notes on modifications and additions to the oxalate developer will be found in the Appendix.
Pyrogallol Developers. Alkaline pyrogallol, having a great tendency to the production of unpleasant brown tones, and also to give rise to stains, has never yet found much favour for enlarging purposes, and therefore no formula will be given for this, although a few workers have advised its use.
Quinol Developers. Hydroquinone, or quinol, has been used
90