A modification of Mr. Talbot's process, to which the name of Chrysotype
was given by its discoverer, Sir John Herschel, was communicated in
June 1843 to the Royal Society, by that distinguished philosopher.
This modification would appear to unite the simplicity of photography
with all the distinctness and clearness of calotype. This preparation
is as follows.
The paper is to be washed in a solution of ammonio-citrate of iron; it
must then be dried, and subsequently brushed over with a solution of
the ferro-sesquicyanuret of potassium. This paper, when dried in a
perfectly dark room, is ready for use in the same manner as if
otherwise prepared, the image being subsequently brought out by any
neutral solution of gold. Such was the first declaration of his
discovery, but he has since found that a neutral solution of silver is
equally useful in bringing out the picture. Photographic pictures
taken on this paper are distinguished by a clearness of outline foreign
to all other methods.