Silver Developing Solution.
| Nitrate of silver | 1 | drachm. |
| Acetic acid | 2 | drachms. |
| Distilled water | 7 | ounces. |
Dissolve the nitrate of silver in the distilled water, and then add the acetic acid.
Fixing Solution.
| Hyposulphite of soda | 2 | ounces. |
| Water | 1 | pint—dissolve. |
Varnish.
The varnish best adapted for this purpose is that supplied by Home & Thornthwaite, and termed negative varnish.[H]
[H] In this country, Humphrey's Collodion Gilding is the article in almost universal use.
Cleaning the Plate.
The plates must be cleaned in the usual way, merely premising that extra care must be observed to remove every impurity, as cleanliness in photography is an absolute necessity.