128 PHOTOGRAPHIC FACTS AND FORMULAS 
A. Alum 10 per cent solution, or 
B. Chrome alum 2 per cent solution, or 
C. Formaldehyde 10 per cent solution 
With the last bath, freedom from hypo is not so essential. 
Practically, the use of these baths has been rendered obsolete 
by the use of the chrome alum fixing baths. 
CLEARING Batus.—These baths are not much used at the 
present day when the use of sulphite and the newer developers 
prevents the staining of the gelatine, which was so prone to 
occur in the early days of the gelatine plate, when plain 
pyrogallol developer was used. The well-washed negatives 
may be immersed in: 
Potassium permanganate lg Ai eu 
Water 1000 ccm 16 oz. 
for 5 minutes, then rinsed in water and immersed in a 1 per 
cent solution of potassium metabisulphite, or sodium bisul- 
phite, or in: 
Alum 200 g 3 Oz: 
Citric acid 65 g 1 oz 
Water 1000 ccm 16 oz 
Or: 
Alum 50 g 34 Oz 
Citric acid 50 g 34 OZ 
Ferrous sulphate 150 ¢g 214 oz 
Water 1000 ccm 16 oz 
Or: 
Chrome alum 25g 192 gr 
Sodium bisulphite 100 g 770 gr 
Water 1000 ccm 16 oz 
(Dr: 
Thiocarbamide 20 g 154 gr 
Citric acid 10g 77 gr 
Water 1000 ccm 16 oz 
