Intensification.—It sometimes happens (especially when too little light has been used to properly judge development) that one acquires a collection of prints that, owing to under or over-development, are useless; let us see how they may be rendered serviceable.
An under-developed print, though weakly looking and "washed out," simply needs intensification to give it the requisite pluck. The foregoing uranium bath acts as an intensifier while conferring a ruddy tone on the deposit. A black deposit can be obtained by intensifying the well-washed print with mercury. The print must first be immersed in a saturated solution of mercuric chloride until the image disappears; it must then be again thoroughly washed to remove all traces of free mercury and may then be redeveloped by flowing over it an old ferrous-oxalate developer. If ferrous oxalate is not at hand, an old metol developer may be substituted, but the former is the more reliable.
When the image is sufficiently intense, the print must once more be thoroughly washed. All the toning and intensifying operations may be conducted by daylight.
Reduction of Density.—Over dense prints can be made fit for many purposes by means of a "reducer" capable of dissolving part of the deposit. The best for the purpose and the one least liable to cause stains is know as the Belitzski's; it is prepared thus:—
| Water | 60 | ounces. |
| Potassium ferric oxalate | 3 | " |
| Sodium sulphite | 3 | " |
Dissolve and add to the red solution so obtained.
| Oxalic acid | 1 | ounce. |
Shake until the solution turns green and then immediately pour off the solution from any crystals remaining undissolved. To this solution add
| Hyposulphite of soda | 15 | ounces. |
and shake until dissolved, when it is ready for use.