AN IMPROVED PROCESS OF PHOTO-CHEMICAL PRINTING
Year: 1878

page_text: LETTERS PATENT to William Willis, junior, of Bromley, in the County of
Kent, for the Invention of "AN IMPROVED PROCESS OF PHOTO-CHEMICAL
PRINTING."
Sealed the 1st November 1878, and dated the 12th July 1878.
PROVISIONAL SPECIFICATION left by the said William Willis at the Offic
of the Commissioners of Patents on the 12th July 1878.
WILLIAM WILLIS, junior, of Bromley, in the County of Kent. "AN IMPROVED
PROCESS OF PHOTO-CHEMICAL PRINTING,"
This Invention is based upon the process described in the Specification of my
former Letters Patent, dated June 5, A.D. 1873, No. 2011, which process consists
in the production on suitable surfaces, such as paper, wood, silk, prepared canvas,
and others, of photographic pictures in platinum, iridium, and other metals by the
application of solutions of potassic, aminonic, or other suitable oxalate to such
surfaces after they have been exposed to light or insolated under a negative or other
suitable object, and which surfaces have been coated previous to such insolation
with ferric and other salts, one of which is a salt of the metal in which the picture
is to be produced.
But although good effects are produced by the process above set forth, I have
discovered means which I employ in my present Invention and thereby obtain
greatly superior results in a more simple, economical, and expeditious manner than
heretofore.
The said Invention consists in the addition of a salt of platinum, or of iridium,
or of mercury to the solution of potassic, ammonic, or other oxalate, used as
described in the said former Specification.
According to this Invention I proceed as follows, that is to say:-I coat paper
with an aqueous solution, each fluid ounce of which contains 15 grs. potassic chloro-
platinite, 70 grs. ferric oxalate (with enough oxalic acid to render this ferric oxalate
soluble), and 4 grs, of lead chloride. I then dry the paper and expose it to light

page_text: under the negative or other object from which the picture or image is to be produced
on this prepared paper. On removing the paper from this negative or other object
I float the said paper face downwards on a hot aqueous solution, each fluid ounce of
which contains 100 grs. potassic oxalate and 6 grs. potassic chloro-platinite. This
solution quickly deepens or intensifies the picture or image produced of the coated
paper by the action of light. I then wash the paper in a weak solution of acid
(preferably oxalic acid), then in plain water, and finish by immersing it for a short
time in a solution of hypo-sulphite of soda, followed by a slight wash in plain
water.
I vary the composition of the coating solution or solutions as follows:-
I sometimes substitute 15 grains of iridium chloride for the potassic chloro-
platinite used as above specified; all other operations the same.
In some instances I omit the chloride of lead in the coating compound or solution,
and in this case I dispense with the final treatment with hypo-sulphite of soda.
In other cases I proceed as in the first-described method, but substitute for the
4 grs. chloride of lead, 10 grs. perchloride of mercury, the treatment being otherwise
conducted as in the first-described method.
For coating the paper or other surface previous to its insolation or exposure to
light I may use salts of other metals than those above named, such as salts of gold
or palladium, or mixtures of these with other salts; but it is essential in all cases
that ferric oxalate shall form one of the ingredients or constituents of the coating
or coatings applied to the said surfaces.
Instead of effecting the coating of the paper or other surface with the aforesaid
salts by using the same all in one solution, I may in some instances find it desirable
to apply such salts in different and successive solutions.
I wish it understood that I do not intend to confine myself to the use of aqueous
solutions of the chemicals herein-before specified, as the salts may be dissolved
and used with any suitable solvent.
Neither do I restrict myself to the exact proportions of the chemicals used in the
above-described process as herein-before stated, as these proportions may be varied
within certain limits, according to the results desired to be obtained or other
conditions.
Nor do I confine myself to the use of the potassic chloro-platinite as an addition
to the potassic oxalate in the solution which I apply to the insolated surfaces, but
may use other salts of platinum, iridium, or mercury, such as platinic chloride,
potassic chloro-platinate, or sodic, ammonic, or baric, chloro-platinite, chloride of
iridium, or bichloride of mercury. But although these and other salts of the above-
named metals (namely, platinum, iridium, and mercury) when added to or mixed
with the potassic oxalate will produce good results, I prefer to employ the potassic
chloro-platinite for the purpose of my Invention, as above set forth.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Willis in the Great Seal Patent Office on the 11th
January 1879.
"
WILLIAM WILLIS, junior, of Bromley, in the County of Kent. AN IMPROVED
PROCESS OF PHOTO-CHEMICAL PRINTING."
This Invention is based upon the process described in the Specification of my
former Letters Patent, dated June 5th, A.D. 1873, No. 2011, which process consists
in the production on suitable surfaces, such as paper, wood, silk, prepared canvas,
and others, of photographic pictures in platinum, iridium, or other metal by the
application of solutions of potassic or ammonic oxalate to such surfaces after they
have been exposed to light or insolated under or behind a negative or other object,
and which surfaces have been coated previous to such insolation with ferric and
other salts, one of which is a salt of the metal in which the picture is to be
produced.
But although good results are produced by the process above set forth, I have
discovered means whereby I obtain greatly superior results in photo-chemical
printing and produce pictures or images characterized by great permanence, and am
enabled to effect such printing in a more simple and certain manner, and with
greater uniformity in the results than heretofore; and these improved means form
the subject of my present Invention.
The said Invention consists in an improved process of photo-chemical printing,
whose essential feature is the addition of a salt of platinum, or of iridium, or of
mercury to the solution of potassic or ammonic oxalate used as described in the
said former Specification, and which improved process is as follows, that is to say :-
The application to paper or other surfaces of a solution consisting of potassic or
ammonic oxalate mixed with a salt of platinum, of iridium, or of mercury after
such paper or other surface has been exposed to light under or behind a negative or
other object, and which paper or surface has previously to such exposure to light
received a coating of or has been treated with ferric oxalate and with other salts,
one of which is a salt of the metal in which the picture or image is to be produced
on the said paper or other surface.
According to the said Invention I proceed as follows, that is to say:-If paper is
used I coat the same with an aqueous solution which I term the coating solution,
and which must contain as one of its ingredients a salt of the metal in which the--
picture or-image is to be produced. For instance, when I desire to produce the
picture in metallic platinum each fluid ounce of this solution will contain about
15 grains of potassic chloro-platinite, 70 grains of ferric oxalate (with enough oxalic
acid to render this ferric oxalate freely soluble), and preferably two grains of
plumbic chloride. I then dry the paper and expose it to light under or behind the
negative or other object from which the picture or image is to be produced on the
prepared paper for a sufficient time, which will usually be indicated by the image
or picture becoming faintly visible. I then float the said paper with its face or
coated surface downwards on or immerse it in an aqueous solution, preferably hot,
which I term the developing solution, and whose use in the process constitutes the
novel and essential feature of my Invention. Each fluid ounce of this developing
solution contains about 120 grains of potassic oxalate and 7 grains of potassic
chloro-platinite, or other salt of the kind herein-after specified. This solution
quickly deepens in color or blackens the picture or image produced on the coated
paper by the action of light. I then wash the paper in a weak solution of some
acid (preferably oxalic acid), and finish by washing it in plain water.
The coating solution or solutions for treating the paper or other surface previous
to its insolation or exposure to light constitutes no part of my Invention irrespective
of the subsequent treatment of the coated surfaces by the developing solution; and
I may use other salts of platinum in this coating solution, or salts of other metals

page_text: than those above named, such as salts of gold, of iridium, or of palladium; but it
is essential in all cases that ferric oxalate should form one of the ingredients or
constituents of the coating or coatings applied to the said surfaces.
The following are examples of the manner in which I vary the composition of
the said coating solution or solutions :-
I sometimes substitute 15 grains of iridium chloride for the potassic chloro-
platinite used as above specified; or I substitute for the two grains of plumbic
chloride 4 grains of mercuric chloride. In other cases I omit the plumbic chloride
in the coating compound or solution.
Instead of effecting the coating of the paper or other surface with the aforesaid
salts by using the same all in one solution, I may in some instances find it desirable
to apply such salts in different successive solutions, and dry the paper, if necessary,
between the successive coatings.
I do not confine myself to the use of the potassic chloro-platinite as an addition
to the aforesaid developing solution, that is to say, the solution of potassic oxalate,
which I apply to the insolated surfaces, but may use other salts of platinum or salts
of iridium or mercury, such as platinic chloride, potassic chloro-platinate, or sodic,
ammonic, or baric chloro-platinite, iridic chloride, or mercuric chloride. But although
these and other salts of the above-named metals (namely, platinum, iridium, and
mercury) when added to or mixed with the potassic oxalate will produce good
results, I prefer to employ the potassic chloro-platinite for the purpose of my
Invention, as above set forth.
Nor do I intend to confine myself to the use of aqueous solutions of the chemicals
herein-before referred to, as the salts may be dissolved and used with any suitable
solvent.
Neither do I restrict myself to the exact proportions of the chemicals used in the
above-described process, as above stated, as these proportions may be varied within
certain limits, according to the results desired to be obtained or other conditions.
In the final treatment of the paper or other material I do not confine myself to
the use of acids, but may employ a solution of any other suitable substance capable
of dissolving out the salts or chemicals which may be left in the paper.
Having thus fully described the said Invention, and the manner of performing
the same, I wish it understood that I claim the improved process of photo-chemical
printing, wherein I employ the aforesaid developing solution consisting of a salt of
platinum, of iridium, or of mercury mixed with potassic or ammonic oxalate, as
and for the purposes specified.
In witness whereof, I, the said William Willis, junior, have hereunto set
my hand and seal, this Tenth day of January, in the year of our Lord One
thousand eight hundred and seventy-nine.
W. WILLIS, JUN*. (L.S.)