A photographic print, however, on either albumenised or "Matt" paper will certainly disappear utterly if subjected to the following bath, for which formula I am indebted to Mr. E.J. Wall:—
| Iodine | 1 grain |
| Iodide of Potassium | 10 grains |
| Cyanide of Potassium | 20 " |
| Water | 102 " |
This is a similar solution as is used to remove ink-stains from linen, &c.
The print may also be bleached by sponging over with the following preparation, recommended by W. Ethelbert Henry:—
| Saturated Solution Iodine in Alcohol | 1 part |
| "" Cyanide of Potassium in Water | 2 parts |
| Water | 2 " |
After which the print is to be washed well for a few minutes.
Of course the reason for using a "fixed" ink in such processes is obvious.
Yet another method on similar lines, but even simpler in operation. A certain photographic printing paper called "Ferro-prussiate" paper gives, on exposure to light, a blue image, and only requires washing in water to "fix" or make it permanent. This blue print can now be used for drawing upon, as in the previous instance, only that the photographic image, being blue, does not need to be bleached, and will not interfere with the reproduction of the black lines drawn upon it.
If for any reason it be desired to get rid of the blue print, this can be bleached by immersion in water containing a little common washing soda.