The best rule is to print the lightest shade on the positive very decidedly darker than it would be wished that it should remain permanently.
To fix the Positive.—On removing it from the pressure frame, place it in a bath made as follows:
| Water | 6 oz. |
| Hyposulphite of soda | 1 oz. |
| Nitrate of silver solution, 50 grs. to oz. | 15 minims. |
| Iodide of silver, dissolved in a saturated solution of hypo. | 10 minims. |
| Chloride of gold | 2 grains. |
| Chloride of silver (blackened by light) | 5 grains. |
| Acetic acid | 2 drops. |
Mix these: let them stand some hours; and filter before use. If the chloride of silver is omitted, the bath will do very well, but will very much improve with age, as it will acquire chloride of silver from the positives placed in it.
The time to leave the positive in the fixing bath varies from one hour to twelve. To get good black and white tints, the average time is five or six hours. When the desired tint is obtained, remove it into a bath composed of
Water 6 oz.
Hypo. 1 oz.
Leave in this for half an hour, and then keep it in running water for several hours. If the water is hot, the time of soaking may be lessened: boiling water is objectionable. Nearly dry the positive between sheets of clean blotting-paper, and finish it by passing a very hot iron over it.
General Remarks.—The albumenised paper will keep any length of time in a dry place.