And I glued it in this manner to a previously-warmed plate of glass, avoiding, of course, all air-bubbles. After having left it for drying, I removed the paper with benzine, and the picture remained perfect on the glass.
It is advantageous to cover the paper on the back, after drying, with a solution of—
| Chromate of Alum, | 1 part. |
| Water, | 300 parts. |
Dissolve off, as usual, with benzine. Should there be any difficulty in removing the picture, it is advisable to place it in benzine in the manner described above.
The transfer to porcelain (opal glass), is performed in the same manner. This gives very pretty effects, but great care must be exercised in dissolving them off.
It is self-evident, that this process is of great importance for the email and porcelain photographs.
If, to the pigment of the first gelatine sheet, an email color has been mixed, a picture will be obtained which can be burnt in.
Another interesting circumstance, I only wish to indicate. In the pictures on glass, we evidently have a carbon (pigment) positive. From this, it will be easy, by repeating the process, to produce a carbon negative.
We would thus be enabled to multiply our negatives, and to produce, instead of the perishable silver negatives, permanent ones by the carbon or pigment process.
FAILURES, FAULTS, AND REMEDIES.
Before proceeding further, a brief recapitulation of the causes of failure in Mr. Swan's process, and the remedies, may not be out of place.
Spontaneous Insolubility of the Tissue.—This, as has been said, arises chiefly from slow drying, or, long
