| Silver nitrate | 50 | grains |
| Citric acid | 20 | " |
| Water | 1 | ounce |
The paper is floated for the ordinary length of time, when it is dried thoroughly and placed between sheets of pure blotting-paper. It will keep in its pristine state for months, if excluded from the air. It is better to fume this paper strongly before use, or the toning becomes a difficult matter.
Ordinary sensitized paper may be preserved for a considerable time if, when dry, it is placed between sheets of blotting-paper saturated with a solution of carbonate of soda, and dried.
Washed sensitized paper is also improved in sensitiveness by floating it for a few seconds on—
| Citric acid | 20 | grains |
| Potassium nitrite | 10 | " |
| Water | 1 | ounce |
It can be fumed, when dried, in the usual manner.
In the Year-Book of Photography for 1880 Mr. A. Borland recommends the following modification:—
He floats the paper on nitrate of silver, as usual, and after it has drained surface dry, blots off any drops that may remain at the edges, and then floats the back of the paper for about three minutes on the following bath:—
| Nitrate of soda | 1 | ounce |
| Distilled water | 16 | ounces |
This is rendered slightly acid by a little solution of freshly prepared citric acid in water. The degree of acidity is regulated by litmus paper (the blue specimen), which should be slightly reddened by it. After this solution has been mixed about ten minutes, it is filtered, and the paper floated. Mr. Borland says the paper keeps well, and prints the same as ordinary paper, and any tone may be produced.