| Saturated solution of alum | 20 ounces |
| Hydrochloric acid | 1 ounce |
Immerse negative after fixing and washing. Wash well after removal.
Reducer For Gelatin Dry-plate Negatives.—
| I.— | Saturated solution of ferricyanide of potassium | 1 part |
|---|
| Hyposulphite of sodium solution (1 in 10) | 10 parts |
| II.— | Perchloride of iron | 30 grains |
|---|
| Citric acid | 60 grains |
| Water | 1 pint |
Belitski’s Acid Ferric-Oxalate Reducer for Gelatin Plates.—
| Water | 7 ounces |
| Potassium ferric oxalate | 2 1/2 drachms |
| Crystallized neutral sulphite of sodium | 2 drachms |
| Powdered oxalic acid, from | 30 to 45 grains |
| Hyposulphite of soda | 1 1/2 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 {536} ferrous, the preparation must be kept in subdued light, in non-actinic glass bottles.
Orthochromatic Dry Plates—erythrosine Bath (Mallman And Scolik).
| Water | 200 cubic centimeters |
| Stronger ammonia | 2 cubic centimeters |
Soak a plate for 2 minutes.