MATERIALS AND PROCESSES FOR PHOTO-CHEMICAL PRINTING
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by the said William Willis at the
Office of the Commissioners of Patents on the 15th March 1880.
WILLIAM WILLIS, junior, of Bromley, in the County of Kent.
MATERIALS AND PROCESSES FOR PHOTO-CHEMICAL PRINTING."
"IMPROVED
My present Invention is based partly upon the process of photo chemical printing
described in the Specification of my former Letters Patent, dated June 5, A.D. 1873,
No. 2011. According to the said process the paper or other surface was coated
with a solution of platinum, iridium, or gold, or a mixture of these salts, and
sometimes other salts, and then with ferric oxalate or tartrate. In practising the
said Invention it was found necessary to use a salt of lead or of silver, and after
exposure to light the said surface was treated with a solution of potassic or other
suitable oxalate; but I have now discovered that I can dispense with the lead
and silver salts, and by avoiding their use can obtain greatly superior results. By
this improvement all danger of discolouration of the white portions of the prints
arising from the use of metals other than iron or platinum is completely avoided.
Moreover, this improved process will be simpler than the said former process, and
will obviate all liability to failure otherwise than from improper exposure or
carelessness.
My present Invention comprises the improved paper or other surfaces or materials
prepared and rendered sensitive for photographic purposes by the application of a
coating solution containing platinous and ferric salts in such proportions or
quantities as hereinafter specified.
-
The said Invention also comprises an improved process consisting in first
preparing the paper or other surface by the use of the platinous coating hereinafter
specified, the exposing it to light under or behind a negative, and then developing
the picture by means of any suitable solution.
The said Invention also comprises the application of improved developing
solutions to paper or other surfaces which have been coated with platinous and
ferric salts.
One distinguishing feature of my present Invention is the comparatively large
quantity of the platinous salt used in coating the paper or other material, that is to say,
in my present improved process I do not employ less than one and seven tenths (1·7) of
Prins 1

page_text: a grain of the platinous salt for each square foot of surface to be coated, and I prefer to
use a much larger quantity, that is to say, as much as four (4) grains of such salts,
and sometimes more for each square foot of coated surface. In the practise of the
Invention described in the said former Specification the quantity of platinous salt
used did not exceed two thirds (3) of a grain for each square foot of surface
coated.
By the use of such a greatly increased quantity of the platinous salt in the
coating I obviate the necessity for the addition of this salt to the developing
solution as described in the Specification of my Patent, dated 12th June, A.D. 1878,
No. 2800, thus simplifying the process while obtaining the superior result, which
is one of the objects of this Invention.
The aforesaid improved developing solutions may be applied to the paper or other
material which previous to its exposure to light has been coated with iron and
platinous salts mixed in the proportions hereinafter specified, or in different
proportions and with or without the addition of a salt of lead or of mercury.
In practising my Invention I form a sensitive surface by applying to paper or
other suitable surfaces a coating containing a platinous salt and oxalate of iron.
The platinous salt I prefer to employ is the potassic-chloro-platinite. I use this
salt in such proportion or quantity that each square foot of the surface will receive
when coated not less than one and seven tenths (17) of a grain of it, but usually a
much greater quantity, that is to say, about four (4) grains of the salt and sometimes
more. The iron salt I prefer is the ferric oxalate.
The platinous salt and the iron salt may be mixed in the desired proportions and
dissolved in a suitable quantity of water and then may be applied to the paper or
other surface, or solutions of these salts may be applied separately. I prefer to use
for ordinary purposes an aqueous solution containing in each fluid ounce sixty (60)
grains of potassic-chloro-platinite and sixty (60) grains of ferric oxalate for application
to paper and to other suitable surfaces.
The paper thus coated, after being dried, is ready for use, and after its exposure
to light or under or bebind a negative I apply to it a developing solution containing
potassic oxalate or either of my improved developing solutions. I prepare an
improved developing solution as follows, that is to say :-I use for the solution the
tartrate or the citrate of soda, of potash, or of ammonia, or any compound of these
salts, or any of them with each other. Or I use the acetate of soda, or the
monammonic or diammonic, orthophosphates, and other salts of tartaric, citric,
acetic, and phosphoric acids. I prefer, however, to use the citrate of soda; I use
one or more of the above named salts, or mixtures of these salts, which will serve
the same purpose alone or mixed with other salts of platinum or of iridium, as
described in the Specification of my said former Letters Patent, No. 2800.
I apply developing solution thus prepared to the paper or other surface coated
according to the first part of my present Invention with platinous and iron salts,
or to surfaces that have been coated with platinous and iron salts used in proportions
different from those specified in the said first part of my Invention; I also apply
the said developing solution to paper or other surfaces that have been previously
coated with platinous salts, ferric oxalate, and salts of lead or mercury, as described
in the Specifications of my said former Patents.
I prepare this developing solution as follows, that is to say:-I make a solution
containing 120 grains of citrate of soda in one ounce of water, or a sufficiently
strong solution of either or any of the other salts above specified. This solution
may be applied to the prepared paper or other surface by pouring it over the same,
or by immersing the paper therein. It may be applied cold, warm, or hot, but
preferably hot. The strength of the solution may be varied, but the best results
will usually be obtained by a strong solution. To this solution of citrate of soda,
or of any or either of the other salts I may, as above specified, add a salt of platinum
or iridium, as specified in the Specification of my said former Patent. I prefer the
potassic chloro-platinite.

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 15th September
1880.
WILLIAM WILLIS, junior, of Bromley, in the County of Kent. "IMPROVED
MATERIALS AND PROCESSES FOR PHOTO-CHEMICAL PRINTING."
My present Invention is based partly upon the proccess of photo-chemical
printing described in the Specification of my former Letters Patent, dated June
5th, A.D. 1873, No. 2011. By the said process the paper or other surface was
coated with a solution of platinum, iridium, or gold, or a mixture of these salts, and
sometimes other salts, and then with ferric oxalate or tartrate. In practising the
said process it was found necessary to use a salt of lead or of silver, and after
exposure to light the said surface was treated with a solution of potassic or other
suitable oxalate, but I have now discovered that I can dispense with the lead and
silver salts, and by avoiding their use can obtain greatly superior results. By this
improvement all danger of discolouration of the white portions of the prints
arising from the use of metals other than iron and platinum is completely avoided.
Moreover this improved process will be simpler than the said former process, and
will obviate all liability to failure otherwise than from improper exposure or
carelessness.
My present Invention comprises paper or other material with its surface prepared
and rendered sensitive for photographic purposes by the application of a coating
solution containing platinous and ferric salts in such proportions or quantities as
are hereinafter specified. The term platinous is used in this Specification in its
chemical sense to distinguish the salts designated by it from those known as
platinic salts.
0
The said Invention also comprises an improved process consisting in first pre-
paring the paper or other surface by the use of the coating containing platinous
and ferric salts as hereinafter specified, then exposing it to light under or behind a
negative, and then developing the picture by means of any of my improved
solutions or other suitable developers.
The said Invention also comprises improved developing solutions to be applied
to paper or other surfaces which have been coated with platinous and ferric salts.
These improved developing solutions may be applied to the paper or other
material which previous to its exposure to light has been coated with ferric and
platinous salts mixed in the proportions hereinafter specified or in different pro-
portions and with or without the addition of a salt of lead or of mercury.
One distinguishing feature of my present Invention is the comparatively large
quantity of the platinous salt used in coating the paper or other material, that is to
Bay, in my present improved process I do not employ less than one and seven
tenths (17) of a grain of the platinous salt for each square foot of surface to bo
coated, and I prefer to use a much larger quantity, usually as much as four (4) grains
of such salt, and sometimes more, for each square foot of coated surface, whereas in
the practice of the Invention described in the said former Specification the quantity
of platinous salt used did not exceed two thirds (3/3) of a grain for each square foot
of the surface coated.
By the use of such a greatly increased quantity of platinous salt in the coating I
obtain results greatly superior to those obtained by the process described in my
said former Specification. I also obtain results superior to those obtained by the
improved process described in the Specification of my Patent dated 12th July,
A.D. 1878, No. 2800, while obviating the necessity for the addition of a platinous
alt to the developing solution as described therein, and thus simplifying the
process.
The platinous salt I prefer to employ is the potassic chloro-platinite. I use this

page_text: salt in such proportion or quantity that each square foot of the surface will receive,
when coated, not less than one and seven tenths (17) of a grain thereof, but usually
a much greater quantity, that is to say, about four (4) grains of the salt, and
sometimes more. The iron salt I prefer is the ferric oxalato.
The platinous salt and the iron salt may be mixed in the desired proportions, and
dissolved in a suitable quantity of water, and then applied to the paper or other
surface, or solutions of these salts may be applied separately. I prefer to use for
ordinary purposes an aqueous solution containing in each fluid ounce sixty (60)
grains of potassic chloro-platinite and sixty (60) grains of ferric oxalate for
application to the paper or other suitable surface. I do not confine myself to this
proportion of ferric oxalate, but may use less or more, according to the result desired
to be obtained. This solution is applied to the paper or other surface by means of
a pad of cotton wool or flannel, or the paper may be coated with it by any of the
means known to photographers.
The paper thus coated is after being dried ready for use, and after its exposure
to light under or behind a negative I apply to it a developing solution containing
potassic oxalate or either of my improved developing solutions. The developing
solution of potassic oxalate is made by dissolving one hundred and twenty (120)
grains or more of the salt in one fluid ounce of water. As soon as the print has
been developed by means of this solution I wash it, first in a weak solution of acid,
preferably citric acid, and afterwards in water.
I prepare an improved developing solution as follows, that is to say:-I use for
this solution the tartrate or the citrate of soda, of potash, or of ammonia, or any
compound of any of these salts with each other. Or I use the acetate of soda, of
potash, or of ammonia or the monammonic, the diammonic or the monosodic ortho-
phosphates; I prefer however to use the citrate of soda. I use one or more of the above
named salts or mixtures of these salts, or other salts which will serve the same
purpose, alone or mixed with the salts of platinum or of iridium, as described in the
Specification of my said former Letters Patent, No. 2800.
I apply the developing solution thus prepared to the paper or other surface
coated according to the first part of my present Invention with platinous and iron
salts or to surfaces that have been coated with platinous and iron salts used in
proportions different from those specified in the said first part of my Invention; I
also apply the said developing solution to paper or other surfaces that have been
previously coated with platinous salts, ferric oxalate, and salts of lead or mercury,
as described in the Specifications of my said former Patents.
I prepare this developing solution as follows, that is to say I make a solution.
containing one hundred and twenty (120) grains of citrate of soda in one ounce of
water, of a sufficiently strong solution of either or any of the other salts above
specified. This solution may be applied to the prepared paper or other surface by
pouring it over the same, or by immersing the paper therein, or by floating the
paper thereon. It may be applied cold, warm, or hot, but preferably hot. The
strength of the solution may be varied, but the best results will usually be obtained
by a strong or saturated solution. To this solution of citrate of soda or of any or
either of the other salts I may, as above specified, add a salt of platinum or of
iridium, as specified in the Specification of my said former Patent. I prefer the
potassic-chloro-platinite for this purpose.
In witness whereof, I, the said William Willis, junior, have hereunto set
my hand and seal, this First day of September, in the year of our Lord One
thousand eight hundred and eighty.
W. WILLIS, JUNR. (L.S.)