IMPROVED PHOTOGRAPHIC PRINTING
Year: 1855

page_text: LETTERS PATENT to Alphonse Louis Poitevin, Civil Engineer, of Paris;
in the French Empire, for the Invention of "IMPROVED PHOTOGRAPHIC
PRINTING."
Sealed the 25th April 1856, and dated the 13th December 1855.
PROVISIONAL SPECIFICATION left by the said Alphonse Louis Poitevin
at the Office of the Commissioners of Patents, with his Petition, on the
13th December 1855.
I, ALPHONSE LOUIS POITEVIN, do hereby declare the nature of the said
Invention for IMPROVED PHOTOGRAPHIC PRINTING, to be as follows:
I print photographically with ink of a greasy nature on paper, lithographic
stone, metal, glass, wood, or other suitable material, in the following manner: -
I apply upon the surface which is to receive the design one or more layers
or films of a mixture of equal parts of a concentrated solution of albumen,
fibrine, gum arabic, gelatine, or similar organic substance, and a concentrated
solution of a chromate or bichromate of potash, or of any base which does not
precipitate the organic matter of the first solution. This single or compound
layer or film is then dried if the photographic impression is to be produced by
contact; or it may be used in a moist state when the photographic impression
is to be produced in the camera obscura. In producing the impression by
contact, the surface is covered with a photographic negative picture, or an
engraving, or other transparent or partially transparent object, or screen, and

page_text: then exposed to light, as in the ordinary photographic process. After a sufficient
exposure, the greasy ink or matter is applied to the surface by a ball or dabber,
or by a roller or press, or otherwise, and it will be found to adhere to those
parts only which have been affected by the light. Thus, if the screen employed
be a negative, having the lights and darks reversed, the print will be a positive,
with the lights and darks correct; and, if the screen be a positive, the print
will be a negative. The print may be retained on the surface on which it is
first produced, or it may be transferred or printed upon paper, or other suitable
material, and the operation repeated. I apply various liquid and solid colours
upon paper, cloth, glass, and other surfaces by mixing such colours with the
aforesaid mixture of a chromate or bichromate with organic matter, and apply-
ing this new mixture or combination to the paper, or other fabric, or surface.
The photographic impression is produced upon this prepared surface or mate-
rial by the action of light, as before, and it is then washed with a sponge and
a large quantity of water. The albumen or other organic matter is rendered
insoluble at the parts where it has been acted upon by the light, and the design
is thus produced in the colour which has been employed. Mixtures containing
different colours may be applied to different parts of the surface, corresponding
to different parts of the negative or screen employed to produce the photo-
graphic impression. A design in several colours may thus be produced. The
proportions of the materials may be varied.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alphonse Louis Poitevin in the Great Seal Patent Office
on the 7th June 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALPHONSE
LOUIS POITEVIN, Civil Engineer, of Paris, in the French Empire, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of December, in the year of our
Lord One thousand eight hundred and fifty-five, in the nineteenth year of
ller reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Alphonse Louis Poitevin, Her special licence that I, the said
Alphonse Louis Poitevin, my executors, administrators, and assigns, or such
others as I, the said Alphonse Louis Poitevin, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed, should

page_text: and lawfully might make, use, exercise, and vend, within the United King-
dom of Great Britain and Ireland, the Channel Islands, and Isle of Man
an Invention for IMPROVED PHOTOGRAPHIC PRINTING upon the condition,
(amongst others) that I, the said Alphonse Louis Poitevin, my executors or
adininistrators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of-the
said Invention, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Alphonse Louis Poitevin, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say:-
I print photographically with ink of a greasy nature ou paper; lithographic
stone, metal, glass, wood, or other suitable material, in the following manner.:-
I apply upon the surface which is to receive the design one or more layers
or films of a mixture, of equal parts of a concentrated solution of albumen,
fibrine, gum arabic, gelatine, or similar organic substance, and a concentrated
solution of a chromate or bichromate of potash, or of any base which does not
precipitate the organic matter of the first solution. This single or compound
layer or film is then dried if the photographic impression is to be produced by
contact; or it may be used in a moist state when the photographic impression
is to be produced in the camera obscura. In producing the impression by
contact, the surface is covered with a photographic negative picture, or an
engraving, or other transparent or partially transparent object, or screen, and
then exposed to light, as in the ordinary photographic process. After a sufficient
exposure, if the surface has become dry or has been used in a dry state, it is
moistened with water by means of a sponge, and, while moist, the greasy ink
or matter is applied to the surface by a ball or dabber, or by a roller or press,
or otherwise, and it will be found to adhere to those parts only which have been
affected by the light. Thus, if the screen employed he a negative, having the
lights and darks reversed, the print will be a positive, with the lights and darks
correct; and, if the screen be a positive, the print will be a negative. The
print may be retained on the surface on which it is first produced, or it
may be
transferred or printed upon paper or other suitable material, and the operation
repeated. I thus obtain a design upon lithographic stone, or other suitable
material, from which I am enabled to multiply impressions by the method of
lithographic printing by inking the moistened surface with a greasy ink.
1 apply various liquid and solid colours upon paper, cloth, glass, and other

page_text: surfaces, by mixing, such colours with the aforesaid mixture of a chromate or
bichromate with organic matter, and applying this new mixture, or combina
tion to the paper or other fabric or surface.
The photographic impression is produced, upon this prepared. surface by
the action of light passing through a negative photographic picture,, or an
engraving, or other, suitable object, or screen, or, in the camera obscura, and it
is then washed with a sponge and a large quantity. of water. The albumen or
other organic matter is rendered insoluble at the parts where it has been acted
upon by the light, and the design is thus produced in the colour which has
been employed. Mixtures, containing, different colours, may be applied. to
different parts of the surface, corresponding to different parts of the negative
or screen employed, to produce the photographic impression. A design in
several colours may thus be produced. The proportions of the materials may
be varied.
Having now described the nature of my said Invention, and in what
manner, the, same. is to be performed, I wish it to be understood that what I
claim; is,
.First, the mode, of printing in the manner of lithography, by moistening and
inking with a greasy ink a lithographic stone, or other suitable surface, pre-
pared with chromatized albumen, fibrine, gum, gelatine,. or similar organic
substance, and on which a photographic impression or effect has been produced
in manner, herein before described.
Second, the mode of printing upon paper, cloth, glass, or other suitable
surfaces, by applying to them a mixture of liquid or solid colours with the
aforesaid chromatized. albumen or other organic matter, and exposing to light,
as herein-before mentioned, and afterwards washing away those. portions of
the mixture which have not been acted upon by the light, as..herein-before
described.
In witness whereof, I, the said Alphonse Louis Poitevin, have hereunto
set my hand and seal, this Second day of June, in the year of our 3
Lord One thousand eight hundred and fifty-six.
Witness,
CH. ARMENGAUD, Ing" Civil,
6, Rue Filles du Calvaire, à Paris.
A. L. POITEVIN. (L.S.)