110 PHOTOGRAPHIC FACTS AND FORMULAS 
images, suitable for transparencies. The developer can only 
be used once, as it spoils rapidly. 
Pyrocatechin-Potash._— 
A. Pyrocatechin 200g 302z., 224 gr. 
Sodium sulphite, dry 400 g 7 OZ. 
Water 1000 ccm 16 oz. 
B. Potassium carbonate 120 g 922 gr. 
Water 1000 ccm 16 oz. 
For use mix in equal parts. 
One solution: 
Potassium metabisulphite 100 g 2 Oz. 
Potassium carbonate 150 g 3 0z. 
Water 400 ccm 8 oz. 
Mix in a mortar and add: 
Pyrocatechin 350 g 7 Oz. 
This forms a thick cream which must be stored in well-corked 
bottles. Mix 1 part with 20 parts of water. 
Rapid one-solution developer (Ellon) — 
Sodium sulphite, dry 250 g 4 oz. 
Caustic soda 35 g 269 gr. 
Pyrocatechin 50 ¢ 384 er. 
Water 1000 ccm 16 oz. 
Mix 1 part with 15 parts of water. 
Two-solution (V ogel) — 
A. Sodium sulphite, dry 50 g 384 gr. 
Pyrocatechin 20 g 154 gr. 
Water 1000 ccm 16 oz. 
B. Caustic soda l4¢ 108 gr. 
Water 1000 ccm 16 oz. 
Mix 1 part A, 1 part B with 4 parts water. 
Pyrocatechin-acetone (Hanneke).— 
Pyrocatechin 10g 77 gr. 
