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Scientific American Supplement, No. 286, June 25, 1881 by Various
page 44 of 115 (38%)
photography is advancing with vast strides toward a position that has
the possibility of a marvelous future. In England, especially, great
advances are being made. The recent experiments of our accomplished
colleague, Mr. Warnerke, on gelatine rendered insoluble by light, after
it has been sensitized by silver bromide and developed by pyrogallic
acid, have revealed to us a number of new facts whose valuable results
it is impossible at present to foretell. It seems, however, certain that
we shall thus be able to accomplish very nearly the same effects as
those obtained by bichromatized gelatine, but with the additional
advantage of a much greater rapidity in all the operations. In my own
experiments with the new process of phototypie, I hit upon the plan of
plunging the carbon image, from which all soluble gelatine had been
removed, into a bath of pyrogallic acid, in order to still further
render impermeable the substance forming the printing surface. I also
conceived the idea of afterward saturating this carbon image with a
solution of nitrate of silver, and of subsequently treating it with
pyrogallic acid, in order to still further render impermeable the
substance forming the printing surface. But the process described by Mr.
Warnerke is quite different; by means of it we shall be able to fix
the image taken in the camera, in the same way as we develop carbon
pictures, and afterward to employ them in any manner that may be
desirable. Thus the positive process of carbon printing would be
modified in such a manner that the mixtures containing the permanent
pigment should be sensitized with silver bromide in place of potassium
bichromate. In this way impressions could be very rapidly taken of
positive proofs, and enlargements made, which might be developed in hot
water, just as in the ordinary carbon process, and at least we should
have permanent images. Mr. Warnerke's highly interesting experiments
will no doubt open the way to many valuable applications, and will
realize a marked progress in the art of photography.
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