| Water | 4 | ounces. |
| Protosulphite of iron | 400 | grains. |
Put this into a bottle, and when the crystals are dissolved, it is ready for use. It should be kept filtered, and can be used only once. Now in another bottle put
| Water | 4 | ounces. |
| Nitrate of silver | 48 | grains. |
Remarks.—The impression is to be well washed after the developing solution has been poured off, and then the re-developing solution (that portion containing the protosulphate of iron) can be poured on—the plate being held perfectly level: the surface is completely covered; the water containing the nitrate of silver should then be poured rapidly on, to mix with the iron, when the surface of the impression will instantly commence to blacken; and if the action be allowed to continue for a lengthened period, say one minute, the impression will be ruined.
It is a matter worthy of notice, that there is no perceptible action when the iron solution is poured over the glass; but the action is very energetic the instant the nitrate of silver solution comes in contact with the iron salt and the silver.
As soon as any change can be observed, after the re-developer has been poured over the plate, it should be quickly and copiously washed off with clean water, and then it is ready for the fixing process.
I would dissuade novices in the art from practising with the re-developing solution, until they have first thoroughly mastered the entire process of taking negatives. The developing solution is the only one used by operators generally, and will, with proper care, produce satisfactory results.
Fixing the Image.
| Water | 8 | ounces. |
| Hyposulphite of soda | 4 | ounces. |
Remarks.—This is nearly a saturated solution. The glass can be put in a dish and the solution poured over, or held in the hand, in the same way as the plate in the daguerreotype process. It can readily be seen when a sufficient action has been attained, as the unaltered bromo-iodide of silver will be dissolved, leaving only the reduced surface holding the image.