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Free Books / Reference / 20th Century Formulas Recipes Processes Vol3 / |  |
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Reducer for Gelatin Dry-Plate Negatives |
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This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
Saturated solution of ferricyanide of potassium ........... 1 part
Hyposulphite of sodium solution (1 in 10) 10 parts
Perchloride of iron .. 30 grains
Citric acid.......... 60 grains
Water.............. 1 pint
Water.............. 7 ounces
Potassium ferric oxalate............... 2.5 drachms
Crystallized neutral sulphite of sodium. 2 drachms
Powdered oxalic acid, from.........30 to 45 grains
Hyposulphite of soda. 1.5 ounces
The solution must be made in this order, filtered, and be kept in tightly closed bottles; and as under the influence of light the ferric salt is reduced to ferrous, the preparation must be kept in subdued light, in non-actinic glass bottles.
Preliminary bath:
Water...... 200 cubic centimeters
Stronger ammonia. ... 2 cubic centimeters Soak a plate for 2 minutes.
Color bath: Erythrosine solution (1 in 1,000) . 25 cubic centimeters
Stronger ammonia (0.900)... 4 cubic centimeters
Water...... 175 cubic centimeters
The plate should not remain longer in the bath than 1.25 minutes.
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