112 PHOTOGRAPHIC FACTS AND FORMULAS 
P yro-Soda.— 
A. Sodium sulphite, dry 50 g 1 oz. 
Sulphuric acid 6 ccm 3 drops 
Pyrogallol l4g 122 gr. 
Water 500 ccm 10 oz. 
B. Sodium carbonate, cryst. 50 g 1 oz. 
Water 500 ccm 10 oz. 
For use mix in equal volumes. 
The “B. J”? Pyro-Soda.—Specially recommended by the 
British Journal of Photography. It keeps well and does not 
stain: 
A. Pyrogallol 16.6 g 1 oz. 
Sodium sulphite, dry 66g 4 oz. 
Potassium metabisulphite 16.6 g 1 oz. 
Hot water 1000 ccm 60 oz. 
Mix the sulphite and metabisulphite dry, and add to half the 
water ; boil for one minute, add the pyro, then the remainder 
of the water, and cool. 
B. Sodium carbonate, cryst. 200 g 12'oz. 
Water 1000 ccm 60 oz. 
For use mix 1 part A, 1 part B and 2 parts water. 
Hurter & Driffield Standard Developer Recommended 
for plate testing: 
Pyrogallol 8 parts 
Sodium carbonate, cryst. 40 parts 
Sodium sulphite, cryst. 40 parts 
Water 1000 parts 
Pyro-Caustic (Valenta) —A very rapid stainless developer, 
acting very much like metol: 
A. Sodium sulphite, dry 80 g 615 gr. 
Pyrogallol 25¢ 192 gr. 
Water 1000 ccm 16 oz. 
