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 1/4 minutes.
Paper-sensitizing Processes:
Blueprint Paper.
| A.— | Potassium ferricyanide | 10 drachms |
|---|---|---|
| Distilled water | 4 ounces | |
| B.— | Iron ammonia citrate | 15 drachms |
| Distilled water | 4 ounces |
Mix when wanted for use, filter, and apply to the surface of the paper.
With this mixture no developer is required. The paper after exposure is simply washed in water to remove the unaltered iron salts. The print is improved by immersion in dilute hydrochloric acid, after which it must be again well washed in water.
II.—The following process, credited to Captain Abney, yields a photographic paper giving blue lines on a white ground:
| Common salt | 3 ounces |
| Ferric chloride | 8 ounces |
| Tartaric acid | 3 1/4 ounces |
| Acacia | 25 ounces |
| Water | 100 ounces |