Improvements in and in connection with Photographic Printing.
Year: 1889

page_text: Date of Application, 29th Mar., 1889
Complete Specification Left, 23rd Dec., 1889-Accepted, 15th Feb.,
1890
PROVISIONAL SPECIFICATION.
Improvements in and in connection with Photographic Printing.
I, WILLIAM WALKER JAMES NICOL of Mason College Birmingham in the County
of Warwick Doctor of Science, Lecturer on Chemistry do hereby declare the nature
of this invention to bo as follows:-
PREPARATION OF THE PAPER.
Suitable paper, such as Rives or Saxe, either previously sized or not, with gelatine,
starch, or arrowroot, is coated in any convenient way with a solution of one or other,
or a mixture of the following salts-Ferric Citrate-Ferric Tartrate-Ferric Ammonic
Citrate, or Tartrate-Ferric Sodic Citrate, or Tartrate-Ferric potassic Citrate, or
Tartrate or with other salts of Ferric Iron, the solutions of which are not precipi-
tated by ammonia.
Instead of these, solutions of other Ferric Salts may be used to which has been
added a sufficient quantity of ammonic, sodic, or potassic citrate, or of ammonic,
sodic, or potassic Tartrate, or of the corresponding salts of other acids, so that the
precipitation of the Iron by Ammonia is prevented. To any, or all of these solutions,
thickening material, such as gum, may be added before application to the paper.
PRINTING AND DEVELOPMENT OF THE PAPER.
The paper thus prepared is exposed dry, under the negative, tracing, or plan, to be
copied, until a more or less distinctly visible image is produced.
The paper is then floated on, immorsed in, or in other ways brought in contact with,
a developing solution. This consists of a salt of silver dissolved in a solution of
ammonia, to which have been added suitable quantities of one, or other, or all, of the
following salts Ammonic, sodic, or potassic Citrates, or the oxalates of the above
metals, or the tartrates of these metals, or the corresponding salts of other organic
acids, whose Ferric salts are not precipitated by ammonia, or mixtures of these with
other salts which may be found to alter the tone, or relative light and shade, of the
photographic print.
WASHING OF THE PRINT.
The paper is then immersed in a highly dilute solution of ammonia, to which may
or may not be added one or more of the Ammonic, Sodic, or Potassic Salts of Citric,
Tartaric, or other organic Acid, the Ferric Salts of which are not precipitated by
Ammonia. After the whole of the Silver and Iron Salts has been removed from the
paper by the above solutions the print is washed in water dried and mounted in the
usual manner.
11
1. 1000

page_text: :
COMPLETE SPECIFICATION.
Improvements in and'in connection with Photographic Printing.
I WILLIAM WALKER JAMES NICOL of Mason College Birmingham in the County
of Warwick Doctor of Science Lecturer on Chemistry do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :--
My invention has for its object the production of photographic pictures or images
in silver on paper, wood, or other surfaces.
For this purpose I apply to paper or other suitable material, a coating of a Ferric
Salt, alone or mixed with the other salts hereinafter specially mentioned, the surface thus
prepared is sensitive to light. The Ferric Salt used may be that of any of the Organic
Acids afterwards mentioned, which prevent the precipitation of Iron by ammonia; or
may be any other Ferric Salt sensitive to light, and the precipitation of the iron, is
in this case, prevented by the addition of a Sodium, Ammonium, or Potassium Salt
of one of the Organic Acids, which prevent the precipitation of Iron by ammonia,
and this may be employed either in the solution with which the paper or other
material is coated, or it may be added to one or other of the solutions subsequently
.it
used.
The surface sensitive to light is then exposed to the action of light under a negative
or other screen of similar character when after some time a faint image becomes
visible it is then brought in contact with a solution containing silver, nitrate or
the other salts of silver (subsequently mentioned) dissolved in ammonia to which has
been added potassium oxalate, or the other salts mentioned later which may tend to
increase the rapidity and vigour of the development, alter the tone of the finished
picture, or prevent the precipitation of the iron by the ammonia. The print is then
washed in water, to which has been added ammonia, and a salt of one of the organic acids,
which prevent the precipitation of iron by ammonia. A subsequent washing in water,
followed by drying completes the operation.
Hitherto no means have been known by which, when using Ferric Salts, as sensi-
tisers (i.e. for coating the paper) and developing with solutions containing silver salts,
a print could be obtained, the tone of which was such that toning, with gold or other
metals followed by the use of Sodium-Thio-sulphate could be dispensed with, I
therefore greatly simplify the operations involved, and add to the permanency of the
⚫ finished print.
According to my invention, I use paper, wood, glass, woven or other material, the
surface of which I prepare and render sensitive, by applying to it in any convenient
manner, a solution prepared in one of the following ways:
1. I make a solution of normal Ferric Sodium Citrate (Fe Na, (C, H, O₂) 2)
containing twenty per cent. of the salt as expressed by the above formula, and add to
it five per cent. of normal potassium oxalate (K, C, O₁) but I do not confine myself
to these exact proportions, they may be altered according to the vigour and tone
desired in the resulting picture.
In place of the Ferric Sodium Citrate mentioned above sometimes use other salts
as follows;-Ferric Ammonium Citrate or Ferric Potassium Citrate or the corre
sponding salts of Tartaric Acid also Ferric Tartrate and Ferric Citrate, and I some-
times use a mixture of these Ferric salts with Citric or Tartaric or Oxalic Acid or the
salts of these acids with Potassium Sodium or Ammonium.
I have also been very successful with solutions of Ferric Salts which are precipitated
by Ammonia either alone or with one or other of the above salts and acids. Thus I
have obtained excellent results with the following
II. I make a solution containing five per cent. of normal Ferric Oxalate
(Fе, (C, O₁) 3) and five per cent. normal Ferric Tartrate (Fe, (C. H₁, O₂) 3)—
and one per cent. of Tartaric or Oxalic Acid, in this case the precipitation of the iron
is prevented by modifying the developer or subsequent solutions as stated below. I
3

page_text: Potassium or Ammonium, Citrate, or Potassium, Sodium or Ammonium, Tartrate,
or-Sodium, Potassium Tartrate, may be used in place of the Sodium Citrate in the
above.
The prints are then washed in water and dried.
Having now particularly described and ascertained the nature of my said
invention, I wish it understood that I do not confine myself to the mixtures mentioned
or to the exact proportions of the ingredients given therein but employ on occasion
other mixtures and proportions of the salts particularly mentioned as suitable for my
purpose, nor do I confine myself to aqueous solutions of the said salts, but may for
the purposes of preparing the sensitising and developing solutions use other solvents
where these are permitted by the chemical nature of the salts employed and I therefore
claim as my invention as follows:-
First. The use of paper or other surfaces coated with ferric salts as described
above, to be used for the production of photographic images in silver, along with the
class of developing solutions already given and particularly referred to in my second
claim.
Secondly. The use of solutions of silver salts dissolved in Ammonia in conjunction
with salts of the Alkalies or Ammonium with Oxalic Acetic Boric Citric or Tartaric
Acids, for the purpose of producing on paper or other surfaces previously coated with
Ferric Salts sensitive to light, images in silver which are of such a colour as not to
require toning with gold or other metals.
Thirdly. The combined use of Ammonia and a Potassium Sodium or Ammonium
Salt of Citric or Tartaric Acid in a solution used for washing prints obtained on
surfaces coated with Ferric Salts and developed with solutions of Silver Salts in
Ammonia.
Fourthly. The use of the Solutions
Sensitising Solutions I and II.
Developing Solutions I a. b. and c.
Clearing Solution
Washing Solution
II a. b. and c.
in the way and manner substantially as described and set forth in the foregoing.
Fifthly. The use of an oxydising agent such as Chromic Acid or any of its salts
in a developer prepared as described and set forth.
WILLIAM WALKER JAMES NICOL.
By Henry Skerrett,
Agent for Applicant.
WILLIAM WALKER JAMES NICOL.
By Henry Skerrett,
Agent for Applicant.