118 PHOTOGRAPHIC FACTS AND FORMULAS 
Pyrogallol 28 g 1 oz. 
Oxalic acid 0.5¢ 8 gr. 
Water 225 ccm 8 oz. 
For use make the following solutions, Nos. 1 and 2 and mix 
equal parts: 
1. Pyro solution as above 56 ccm 2 oz. 
Water 500 ccm 18 oz. 
2. Sodium sulphite, dry 28g 1 oz. 
Sodium carbonate, dry l4g YZ 02. 
Water 560 ccm 20 oz. 
Tank developer: 
No. 1 solution 56 ccm 2 oz. 
No. 2 solution 56 ccm 2 oz. 
For 15 minute development add 225 ccm (8 oz.) of water at 
(57) Fe 
For 30 minute development add 560 ccm (20 oz.) of water at 
650 i, 
For Wratten Panchromatic Plates.— 
A. Sodium or potassium bisulphite 6g 90 gr. 
Pyrogallol 30 g 1 oz. 
Water 500 ccm 16 oz. 
B. Sodium sulphite, dry 45¢ LY, oz. 
Water 500 ccm 16 oz. 
C. Sodium carbonate, dry 37.5 g 1% oz. 
Water 500 ccm 16 oz. 
For tray development, mix 1 part A, 1 part B, 1 part C, and 
7 parts water. 
For tank development, mix 1 part A, 1 part B, 1 part C, and 
25 parts water, to which add for every 500 parts, 2 parts of 
1 per cent solution of potassium bromide. 
The times for development for the above tray and tank de- 
velopers are: © 
