222 PHOTOGRAPHIC FACTS AND FORMULAS 
Sodium carbonate, cryst. 10g 77 gr. 
Ammonium nitrate 10g 77 gr. 
Salt 10g 77 gr. 
Water 1000 ccm 16 oz. 
The image bleaches to a bright greyish brown, and should be 
then well washed, and immersed in: 
Potassium bromide 5.5 2 42 gr. 
Glacial acetic acid 16.5 ccm 127 min. 
Ammonium iron alum 5.5 ¢ 42 gr. 
Water 1000 ccm 16 oz. 
As soon as the prints have assumed a steel blue colour, they 
should be well washed, fixed in a 5 per cent solution of hypo, 
again well washed, and immersed for 2 minutes in a 1 per 
cent solution of sulphuric acid. The prints should be rather 
darker than usual, as this process reduces the density slightly. 
VANADIUM ToniInGc.—This gives green tones which vary 
according to the ratio of iron to the vanadium salt and the 
duration of the washing. The colour is dependent on the 
deposition of vanadium ferrocyanide, which is yellow-orange, 
in combination with Prussian blue; with prolonged washing 
some of the latter dissolves; therefore, the green becomes 
brighter. Namias recommended separate baths: 
Potassium ferricyanide 50 g 384 gr. 
Water 1000 ccm 16 oz. 
Ammonia q. Ss. q. S. 
Add enough ammonia to make the solution smell distinctly 
after shaking well. Immerse the bleached and well washed 
prints in a bath compounded of the following stock solutions: 
A. Vanadium chloride, 2 per cent solution 
B. Ferric chloride, 2 per cent solution 
For use take: 
A solution 125 ccm 2 oz. 
B solution 125 coma), 34° 2 oz. 
