DEVELOPERS 95 
Stock solution for Hammer Plates: 
Sodium sulphite 125 ¢ 24 02. 
Edinol 10g 96 gr. 
Sodium carbonate 50 g hoz! 
Water 1000 ccm 20 oz. 
For use mix with an equal volume of water. 
EIKONOGEN.—-A slow acting soft developer: 
A. Sodium sulphite, dry 67 g 514 gr. 
Eikonogen 16.6 g 128 gr. 
Water 1000 ccm 16 oz. 
B. Sodium carbonate, dry 75g 576 gr. 
Water 1000 ccm 16 oz. 
Mix 3 parts A with 1 part B. A more rapid acting developer 
can be made by replacing the soda by an equivalent weight of 
potassium carbonate, namely 98 g (752 gr.). 
One solution: 
Sodium sulphite, dry 60 g 460 er. 
Potassium carbonate 50 g 384 gr. 
Eikonogen 30 g 230 gr. 
Boiling water 1000 ccm 16 oz. 
Keeps well. For use mix with an equal volume of water. 
ErLon.—Another name for Metol, under which heading the 
Eastman Elon formulas may be found. 
FERROUS OXALATE.—The use of this developer has been 
completely abandoned, mainly because plates are actually 
slower when developed with it than with the organic devel- 
opers, and also because of the deposition of calcium oxalate 
and basic iron salts in the gelatine film. On the other hand, 
it has the great advantage of giving an image composed of 
nothing but pure silver which is a neutral colour, that is, 
without selective absorption, and is, therefore, valuable in 
certain photochemical investigations. Ferrous oxalate is a 
yellow stable powder, insoluble in water, which can be pre- 
