IMPROVEMENTS IN PHOTO-CHEMICAL PRINTING
Year: 1873

page_text: LETTERS PATENT to William Willis, junior, of Bromley, in the County
of Kent, for the Invention of "IMPROVEMENTS IN PHOTO-CHEMICAL
PRINTING."
Sealed the 2nd December 1873, and dated the 5th June 1873.
PROVISIONAL SPECIFICATION. left by the said William Willis at the
Office of the Commissioners of Patents, with his Petition, on the
5th June 1873.
I, WILLIAM WILLIS, junior, of Bromley, in the County of Kent,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
PHOTO-CHEMICAL PRINTING," to be as follows:-
This Invention has for its object improvements in the chemical treat-
ment of the surfaces of paper, wood, and other suitable materials
employed for receiving images from photographic negatives or from any
other object that may be interposed between the light and such prepared
paper or other surface. For this purpose I apply to surfaces of paper,
wood, and other suitable materials (by either one or more coatings)
solutions of simple or compound salts of platinum, iridium, or gold, or a

page_text: mixture of such salts.
After this has dried I sometimes apply another
coating of a solution of a salt or salts of other metals. I then coat
the material again, using a solution of ferric oxalate, or tartrate, or a
combination of these salts with others, and again dry. I then expose
the coated surface under a photographic negative till a faint brown
image appears. After this I apply to the coated surface a solution of
the ncutral oxalate of potassium or other suitable oxalate, which speedily
changes the brown tints to black ones; I then wash the surface for a
short time in a dilute acid, afterwards immerse in a solution of hypo-
sulphite of soda, and finally wash in water.
The following are several examples of the operations and manner in
which I employ some of the chemicals above referred to in carrying my
Invention into practice:
-
First Operation.-For the first coating I prefer a solution of the
chloro-platinate or chloro-platinite of sodium; strength of this solution.
8 to 12 grains of the salt to one ounce of water, which I apply to the
surfaces or material to be treated by either floating or brushing.
Second Operation.-After the paper or other material has thus becn
coated and dried I coat it a second time, using a solution of a salt of
silver, of lead, of mercury, or of some other metal, preferring the nitrate
of silver; strength of the solution from 5 to 7 grains of the salt to one
ounce of water.
Third Operation.-When the last coating has dried I apply a third one
consisting of a solution of ferric oxalate, or tartrate, or or of any of the
compounds of those salts. I prefer a solution of ferric oxalate in as little
oxalic acid as is sufficient to dissolve it; strength of this solution 50
to 100 grains of the salt to one ounce of water.
Fourth and Fifth Operations. When the material has been coated with
the ferric oxalate or other salt, and dried, it is ready for exposure to
light, which I usually do under a photographio negative. On removing
it from the negative I apply to the surface, either by floating or other-
wise, a strong solution of potassic oxalate, or of ammonic oxalate, or of
any acid oxalite of those bases, or other salt capable of dissolving ferrous
oxalate without decomposition. I prefer to use a warm solution of
potassic oxalate commonly called the neutral oxalate of potassium.
Sixth Operation.-I remove the picture from the last solution and
wash it for a few minutes in a dilute solution of an acid, preferring the

page_text: citric or tartaric acid. I then give it a slight wash in water, and
immerse it in a solution of hyposulphite of soda; strength about one
ounce of the salt to four ounces of water. After remaining in this
solution from 10 minutes to half an hour I wash the surface of the
material thus treated for about 10 minutes, and dry. It is then
finished.
immerse it in a solution of hyposulphite of soda; strength about one
ounce of the salt to four ounces of water. After remaining in this
solution from 10 minutes to half an hour I wash the surface of the
material thus treated for about 10 minutes, and dry. It is then
finished.
I occasionally vary the preceding operations, or invert their order, or
omit one or more of them,
The following are some of the variations I find desirable for some.
purposes:-
1
1st. I sometimes mix one or more of the substances mentioned in the
first and second operations (previously described) with ferric oxalate.
By this means one coating of the material to be treated before exposure
to light will suffice.
2nd. I sometimes combine the 2nd and 3rd operations (previously,
described) by adding the silver salt to the ferric salt, by which means
two coatings of the material to be treated only are required.
3rd. In the second operation previously described, viz., the coating
of the material to be treated with a silver or other salt, I sometimes
apply this before applying the platinum or other salt, so as to make it
the first operation, or I omit its application altogether.
SPECIFICATION in pursuance of the conditions of the Letters Patent,,
filed by the said William Willis in the Great Seal Patent Office
on the 5th December 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
WILLIS, junior, of Bromley, in the County of Kent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her.
Letters Patent, bearing date the Fifth day of June, in the year of,
our Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give,
and grant unto me, the said William Willis, junior, Her special license.
that I, the said William Willis, junior, my executors, administrators,
'

page_text: The following are several examples of the operations and manner in
which I employ some of the chemicals above referred to in carrying my
Invention into practice.
First Method. I coat paper with a solution of chloro-platinite of
potassium containing 10 grains of the salt to 1 oz. of water. After drying
the paper I coat it again with a solution of the nitrate of lead, 40 grains
of the salt to 1 oz. of water, and dry it again. I then coat it a third
time with a solution composed of ferric oxalate, 60 grains to 1 oz. of
water, with as little oxalic acid as is sufficient to render the fabric
oxalate soluble. I then dry the paper and expose it to light under a
negative. On removing it from the negative I float it face downwards
on a hot solution of potassic oxalate. I then wash it in a weak solution
of oxalic acid, then in plain water, and finish by immersing it in a
solution of hyposulphite of soda followed by a slight wash in plain
water.
Second Method. In this method I proceed as in the first, but sub-
stitute an 8 grain solution of nitrate of silver for the nitrate of lead, and
after removing the prints from the weak solution of oxalic acid I finish
them by an immersion in either a strong solution of chloride of sodium,
or in a weak solution of that salt, followed by a weak solution of
ammonia, supplemented in both cases by a slight wash in plain water.
Third Method. I coat paper with a solution of platinic bromide,
12 grains to 1 oz. of water, and dry. I then coat it with a strong solution
of ferric tartrate, and dry. I next expose this paper to light under a
negative, and afterwards float it face downwards on a hot solution of
potassic oxalate. I then immerse it in a weak solution of oxalic acid,
and finish by washing it in plain water.
I occasionally vary the preceding operations, or invert their order, or
omit one or more of them.
I would remark that I do not 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.
I sometimes mix two or more of the salts used for coating the paper
or other surface before application.
Having thus fully described the nature of my improvements, and the
manner of carrying the same into practice, what I claim for the pro-

page_text: duction (on suitable surfaces) of photographic pictures in platinum,
iridium, and other metals is, the application of solutions of potassio,
ammonic, or other suitable oxalate to such surfaces after they have been
exposed to light under a negative or other suitable object, and which
surfaces have been coated previous to such insolation with ferric and
with other salts, substantially in the manner herein-before described.
In witness whereof, I, the said William Willis, junior, have here-
unto set my hand and seal, this Fourth day of December, in
the year of our Lord One thousand eight hundred and seventy-
three.
Witness,
J. G. TONGUE,
Patent Agent,
34, Southampton Buildings,
Chancery Lane,
W.C.
W. WILLIS, JUN'. (L.S.)