TONING BROMIDE PRINTS Zot 
ferricyanide with the addition of a little potassium oxalate, 
wash well, and treat with a 2 per cent solution of iron 
ammonium oxalate. This salt is the best to use for all iron 
toning baths, as it is stable and of uniform composition. 
Sedlaczek’s formulas are as follows, and all the quantities 
apply to 10 per cent solutions of the salts, unless otherwise 
stated : 
Ammonia iron alum 25 ccm 175 min. 
Potassium citrate 20 ccm 140 min. 
Ammonia alum, sat. sol. 100 ccm 700 min. 
Hydrochloric acid 5 ccm 35 min. 
Potassium ferricyanide 20 ccm 140 min. 
Water 1000 ccm 16 oz. 
This gives a deep blue tone. 
Ammonia iron alum 25 ccm 175 min. 
Potassium oxalate 60 ccm 440 min. 
Ammonia alum, sat. sol. 100 ccm 700 min. 
Hydrochloric acid 5 ccm 35 min. 
Potassium ferricyanide 20 ccm 240 min. 
Water 1000 ccm 16 oz. 
This gives a cold blue. If the hydrochloric acid and alum be 
omitted, and 10ccm (70 min.) of 10 per cent solution of 
tartaric acid be used, a grey blue colour is given. 
Ammonia iron alum 100 ccm 700 min. 
Potassium bromide 60 ccm 420 min. 
Hydrochloric acid 10 ccm 70 min. 
Water 1000 ccm 16 oz. 
This gives a bright blue. 
The following was specially recommended by Pfenninger 
for the blue constituent image in three-colour work. Im- 
merse the print or transparency in the following solution, 
made by weight: 
Potassium ferricyanide 30 g 230 gr. 
