IMPROVEMENTS IN PROCESSES FOR COFYING OR REPRODUCING BY THE AGENCY OF LIGHT DRAWINGS ENGRAVINGS, LITHOGRAPHS, AND PHOTOGRAPHS, AND WRITTEN AND PRINTED DOCUMENTS
Year: 1864

page_text: LETTERS PATENT to William Willis, of Birmingham, in the County of
Warwick, Engraver, for the Invention of "IMPROVEMENTS IN PROCESSES
FOR COFYING OR REPRODUCING BY THE AGENCY OF LIGHT DRAWINGS
ENGRAVINGS, LITHOGRAPHS, AND PHOTOGRAPHS, AND WRITTEN AND PRINTED
DOCUMENTS."
Sealed the 4th April 1865, and dated the 11th November 1864.
PROVISIONAL SPECIFICATION left by the said William Willis at the
Office of the Commissioners of Patents, with his Petition, on the 11th
November 1864.
I, WILLIAM WILLIS, of Birmingham, in the County of Warwick, Engraver,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
PROCESSES FOR COPYING OR REPRODUCING BY THE AGENCY OF LIGHT, DRAWINGS.
ENGRAVINGS, LITHOGRAPHS AND PHOTOGRAPHS, AND WRITTEN AND PRINTED DOCU-
MENTS," to be as follows:-
My Invention consists of the improved process or processes herein-after
described, by which process or processes a drawing, engraving, or other
impression may be copied at one operation, that is to say, a copy may be
produced in which the light and dark parts in the original are directly
reproduced in the copy, and are not reversed as in the ordinary methods of
photographic printing.
I will describe my Invention as applied to the copying of a mechanical
Drawing. Upon the paper collodion or other surface on which the copy is to

page_text: be produced I spread a solution of bichromate of ammonia or other soluble
chromate, mixed with sulphuric acid or other acid capable of combining with
oxide of chromium. The surface is coated and dried in the dark. The
drawing to be copied is placed upon the prepared surface,and exposed under
glass to the action of light similar to the way in which positive photographs
are ordinarily printed. The-length of exposure to light.depends upon the
intensity of the light and the transparency of the paper on which the drawing
is made, and varies ordinarily from four minutes to half an hour. A faint
image is produced by the light, the parts on which light has acted being
bleached, and the parts not acted upon. retaining their original colour. The
impression so obtained is exposed to the action of a solution of a salt of aniline
or to the vapour of aniline, by which treatment it is darkened and made
nearly black. By washing with water the paper or other surface on which
the copy is made, the chemicals employed are sufficiently removed from the
said paper or other material. The copy thus produced is finally dried.
Although I prefer to use aniline for the purpose of darkening the impression
produced by the action of light, yet other substances having analogous
properties may be employed, such, for example, as toluidine, pyrrol, and
furfurol and salts of these bases.
The essence of my Invention consists in obtaining copies or reproductions
by the action of light by preparing a surface with a solution containing a
soluble chromate mixed with an acid, which will combine and form a
compound with the oxide of chromium formed by the action of light, and
darkening the impression produced by the unaltered chromate by means of
aniline or other organic substance capable of forming a dark and insoluble
compound with the said unaltered chromate.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Willis in the Great Seal Patent Office on the
6th May 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME," I, WILLIAM
WILLIS, of Birmingham, in the County of Warwick, Engraver, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of November, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-eighth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the

page_text: said William Willis, Her special licence that I, the said William Willis, my
executors, administrators, and assigns, or such others as I, the said William
Willis, 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 and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man,' an Invention for "IMPROVEMENTS IN PROCESSES FOR
COPYING OR REPRODUCING BY THE AGENCY OF LIGHT, DRAWINGS, ENGRAVINGS, LITHO
GRAPHS, AND PHOTOGRAPHS, AND WRITTEN AND PRINTED DOCUMENTS," upon the
condition (amongst others) that I, the said William Willis, my executors or
administrators, 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 William Willis, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:-
My Invention consists of the improved process or processes herein-after
described, by which process or processes a drawing, engraving. or other
impression may be copied at one operation, that is to say, a copy may be
produced in which the light and dark parts in the original are directly
reproduced in the copy,.and are not reversed, as in the ordinary methods of
photographic printing.
'
I will describe my Invention as applied to the copying of a mechanical
drawing. Upon the paper, collodion, or other surface on which the copy is
to be produced, I spread a solution of bich romate of ammonia or other soluble
chromate mixed with sulphuric acid or other acid capable of combining.with
oxide of chromium. The surface is coated and dried in the dark. The
drawing to be copied is placed upon the prepared surface, and exposed under
glass to the action of light similar to the way in which positive photographs
are ordinarily printed. The length of exposure to light depends upon the
intensity of the light and the transparency of the paper on which the drawing
is made, and varies ordinarily from four minutes to half an hour. A faint
image is produced by the light, the parts on which the light has acted being
bleached, and the parts not acted upon retaining their'original colour. The
impression soobtained is exposed to the action of a solution of a salt of aniline

page_text: or to the vapour of aniline, by which treatment it is darkened and made
nearly black. By washing with water the paper or other surface on which
the copy is made the chemicals employed are sufficiently removed from the
said paper or other material. The copy thus produced is finally dried.
Although I prefer to use aniline for the purpose of darkening the impression
produced by the action of light, yet other substances having analogous
properties may be employed, such, for example, as toluidine, pyrrol, and salts
of these bases. The essence of my Invention consists in obtaining copies or
reproductions by the action of light by preparing a surface with a solution
containing a soluble chromate mixed with an acid, which will combine and
form a compound with the oxide of chromium formed by the action of light.
and darkening the impression produced by the unaltered chromate by means
of aniline or other organic substance capable of forming a dark and insoluble
compound with the said unaltered chromate.
Having explained the nature of my Invention, I will proceed to describe
the manner in which the same is to be performed.
I will describe my Invention as applied to the copying of a drawing in ink,
such as a mechanical drawing on paper.
I first prepare a solution of thirty grains of bichromate of ammonia in one
ounce of water, to which is added about two drams of dilute phosphoric acid
of commerce. The adjustment of this acid in proper proportion to the
chromate is a matter of great importance, and can only be accomplished by
trial on each occasion of making a solution from fresh materials. When too
little acid is used, the picture developes slowly, and is of a reddish brown
colour; when an excess of acid is present, the picture developes quickly, and
is of a blue or green colour. When the proper quantity is present, the picture
developes of a black colour. Sulphuric acid may be used instead of phosphoric
acid, and bichromate of potash instead of bichromate of ammonia. I cover
the sheet of paper on which the drawing is to be reproduced with this solution
either by floating it on the solution contained in a flat dish or spreading the
liquid over it by means of a sponge. The paper thus coated or covered with
the solution is then hung up to dry in the dark. Paper thus prepared will
keep several days without injury. When it is to be used it is placed in an
ordinary photographic printing frame in contact with the drawing, and is then
exposed to light precisely as in the well known process of printing positive
photographs. The time of this exposure will vary from two minutes to half
an hour, according to the intensity of the light. The impressed paper is then
removed from the printing frame, and laid on the bottom of a wooden box,
which is as long and as wide as the sheet of paper, but not more than twọ

page_text: inches deep. To the under side of the cover of this box two or three layers
of bibulous paper are fastened by nails, and a dilute solution of aniline in.
benzole is poured thereon from a dropping bottle in rows of drops, the rows
being about two inches apart. This cover is then laid on the broad and flatly,
planed sides of the box, and the vapour of aniline falls therefrom to the surface
of the impressed paper, and blackens all those parts which have not been
exposed to the action of light. The time required for this development of.
the picture will vary from-ten minutes to half an hour: After the picture has.
been thus developed it is washed for a few minutes in plain water, or first in
water,
then in very dilute sulphuric or other acid, and again in plain water.
The picture is thus fixed or rendered unchangeable by light. The strength
of the solution of aniline in benzole is not material, but a solution of one.
ounce of aniline in sixteen ounces of benzole answers very well.
I vary the different stages of the operation occasionally to suit certain
peculiar requirements. Thus instead of the sensitising liquid previously
mentioned, I sometimes employ thirty grains of chromate of copper dissolved
in one ounce of water and fifteen drops of sulphuric acid, to which one dram.
of the dilute phosphoric acid is also added. Or, again, I sometimes employ.
thirty grains of phosphate of copper dissolved in one ounce of water by the
aid of sufficient sulphuric acid to make a clear solution, and then add fifteen
drops of a saturated solution of chromic acid, but the process first described,
I believe to be on the whole the best.
Instead of aniline for developing, I occasionally employ toluidine, or such
other volatile organic bases as possess the property of striking a black or dark
colour with chromic acid or chromates unacted upon by light. Of these
I prefer at present the series known as the pyrrol bases. When these are
prepared by the distillation of feathers, bones, and other animal substances,
they give a great variety of red, brown, and black tints. They may be used
by dilution with benzole like aniline. That mixture, however, of pyrrol bases
with other organic substances which is obtained by the distillation of the
mucate or bimucate of ammonia is still better, and gives rise to fine blacks.
This last-named mixture is strongly alkaline, and will not develope until it
has been neutralized with sulphuric acid. Lastly, a mixture of aniline, pyrrol,
and other organic products usually produced with these bases, may be used
with good result.
Although I prefer applying the aniline or other organic developer in the
form of vapour, yet the same may be applied in the state of' a dilute solution
with nearly the same effect.
Akhach Thawe only described my Invention as applied to the conving on

page_text: paper of a mechanical drawing made on paper, by which description I believe
the manner of carrying my Invention into effect will be fully understood, yet
my said Invention is applicable to the copying of drawings, engravings, litho-
graphs, photographs, written and printed documents made on any transparent
or semi-transparent material.
My Invention may be employed to take impressions on silk or other fabric,
also on wood blocks for wood engravings, and generally on such materials as
may be used for receiving photographic impressions by the ordinary photo-
graphic processes.
Having now described the nature of my Invention, and the mannerin which
the same is to be performed, I wish it to be understood that I do not limit
myself to the precise details herein described, as the same may be varied
without departing from the nature of my Invention; but I claim as my
Invention the improvements in processes for copying or reproducing by the
agency of light, drawings, engravings, lithographs, and photographs, and
written and printed documents, herein described, that is, preparing the
sensitive surface to be acted upon by light by the use of a solution containing
a 'chromate 'mixed with an acid, which will combine with the oxide of
chromium formed by the action of light, and with the organic base used for
developement, and developing the picture by means of aniline, pyrrol, and
other organic bases, which when applied either in the state of vapour or liquid,
are oxidized by the chromic acid, and form therewith a dark coloured
compound.
In witness whereof, I, the said William Willis, have hereunto set my
hand and seal, this Fifth day of May, in the year of our Lord One
thousand eight hundred and sixth fire
Witness,
GEORGE 'SHAW.
WILLIAM WILLIS. (LS..)