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Scientific American Supplement, No. 492, June 6, 1885 by Various
page 52 of 133 (39%)
represent the blue of the original, in another the yellow, and in another
the red, in such a manner that transparent pigment prints from these
negatives--blue, yellow, and red--would, when superimposed on a white
surface, represent not only the lights and shadows, but also the colors
of the object. This had already been attempted by others, who failed
because their plates were not sufficiently sensitive to red and yellow.

Having succeeded perfectly in my undertakings, I published my discovery
in 1879,[1] explaining how to prepare and use the chlorophyl plates, in
connection with the yellow screen, for the purpose of securing correct
photographs of colored objects.[2]

[Footnote 1: _Philadelphia Photographer_, December, 1879, p. 365.]

[Footnote 2: I intended this publication to be a very full and explicit
one, and it was sufficiently so to be perfectly understood by most who
saw it; but some may think I did not sufficiently emphasize the
importance of using the particular kind of chlorophyl which I mentioned.
In a brief communication to the editor of the _Photo. News_, in 1883, I
described some experiments with eosine as a color sensitizer, and then
called attention to the superiority of blue-myrtle chlorophyl for this
purpose, stating that I had not been able to secure such results with any
other kind of chlorophyl, and that a fresh solution from fresh leaves
must be used to secure the greatest possible degree of sensitiveness. See
_Photo. News_, Nov. 1883, p. 747.]

So far as I know, nobody tried the process. Nearly five years later Dr.
Vogel announced that, after eleven years of investigation, he had at last
realized a successful process of this character, and that this new
process of his was the "solution of a problem that had long been
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