Materials and Sensitive Surfaces for Photographic Purposes.
Year: 1887

page_text: Date of Application, 16th Nov., 1887
Complete Specification Left, 15th Aug., 1888
Complete Specification Accepted, 5th Oct., 1888
Materials and Sensitive Surfaces for Photographic Purposes.
We, ERNEST HOWARD FARMER of 309 and 311 Regent Street in the County
of Middlesex, Professor of photography and HARRY KNEEBONE TOMPKINS B.SC.,
F.I., F.C.S., of the Laboratory, 43 Museum Street in the County of Middlesex,
Consulting Chemist, do hereby declare the nature of this invention to be as follows:-
Our invention relates to the preparation and use of photographic materials as
follows that is to say -The said invention comprises the making of a sensitizing
mixture by the preparation of sensitive silver compounds in albumen according to the
emulsion process, for the production of either negatives or positives; also the manu-
facture of sensitive paper or other material by the application of the sensitive mixture
to its surface. It also comprises an improved process whereby we obtain many
important advantages as hereinafter specified.
We are aware that sensitive surfaces have heretofore been prepared by floating
paper coated with albumen and a haloid salt upon a solution of a salt of silver,
also that sensitive emulsions for producing negative and positive, images have been
prepared in gelatine or collodion, but these methods do not afford results such as
those we seek to produce by our invention.
In practising the said invention we make an emulsion by mixing a silver compound
with a solution of albumen that is to say, we mix a silver salt with the solution of
albumen and then add the haloid compound or salt or other suitable salt; or we bring
together a haloid compound and a silver compound in a solution of albumen. In
some cases we add to the mixture a small quantity of ammonia or carbonate of
ammonia.
We sometimes apply the haloid salt after first coating the surface with the emulsion
of the silver salt in albumen. The mixture or emulsion is washed by dialysis or
other means and then employed for coating glass, paper, or other suitable material the
film being rendered insoluble by the addition of chrome-alum or other suitable
substance to the emulsion or by steaming.

page_text: Our improved process consists in the preparation of the paper or other material
by the application, to its surface, of the aforesaid sensitive mixture and in then, (after
exposure of the sensitized surface to light) developing the image or picture by the use
of a suitable developing solution; or we can, when desirable, print the image entirely
by the exposure to light of the paper or other surface made sensitive as above
set forth.
Our invention affords the following important advantages viz.:-We can obtain
surfaces more sensitive for printing "right out" (that is to say by the action of light
alone) than any now in use. We can obtain, by developement, prints equal to those
obtained by printing by the action of light alone, thereby greatly reducing the
requisite time of exposure to light. We can obtain reduced or enlarged prints more
advantageously than has heretofore been practicable; We can obtain a hard brilliant
surface instead of the soft dull surface obtained with gelatine films. We can intensify
the image with acid silver solutions; We can wash the prints in hot water and thereby
greatly facilitate this operation, and we avoid staining or "frilling" of the film.
Dated this 16th day of November 1887.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements relating to the Preparation and Use of Sensitizing
Materials and Sensitive Surfaces for Photographic Purposes.
We ERNEST HOWARD FARMER, Professor of Photography in the Polytechnic
Institute Regent Street W. and HARRY KNEEBONE TOMPKINS of 43 Museum Street,
London W.C. Chemical Expert 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 :-
Our invention consists in the use of albumen as a medium for emulsifying instead of
gelatin, collodion gum or other colloid used for this purpose in the ordinary processes;
and the application of the said emulsion to the production of albumen prints and
images by development or printing out.
In the preparation of an ordinary gelatin emulsion for producing positives or
negatives a solution of gelatin is taken and solutions of a haloid salt and of silver
nitrate are added alternately to the gelatin with the result that the precipitated
silver haloid is formed in the presence of gelatin; our invention consists in the
precipitation or production of silver salts by the emulsion process in the presence of
pure albumen.
In carrying out our process we take albumen and dissolve it in a soluble haloid salt,
to this is then added a solution of a silver salt, or we dissolve the haloid and silver salt
in separate portions of water and then add them alternately to the albumen.
If the emulsion is intended for the production of paper for printing out the silver
salt may be in excess but if the paper is intended for development the albumen must
be in excess.
The following are good praportions
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page_text: 24
"
20
"
Ammonium Carbonate
Potassium Chloride
20 oz. Water
If the paper is intended for printing out it is sensitized upon a bath of 8-12"/
silver Citrate or other organic salt of silver.
A good sensitizing bath is as follows :-
48 grains Silver Nitrate
20
10
دو
"
Citric Acid
Ammonium Nitrate
1 oz. Water (distilled)
Or sometimes we precipitate Silver Citrate or other sparingly soluble salt of Silver
along with the silver haloid and by this means prepare a paper suitable for printing
out at one operation.
The precipitation is carried out as before.
Sometimes we mix the finished emulsion whether for development or printing out
with a solution of hard gelatin. In this case the chrome alum or coagulation by
alcohol is not necessary.
The emulsion may be used for coating opals or glass as well as paper the film being
rendered insoluble by immersion in alcohol.
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed we declare that what we claim is:
1. The application and employment of pure albumen as a medium in which to
prepare photographic emulsions instead of gelatin, collodion, gum or other colloid
usually employed.
2. The application of the albumen emulsions obtained as described in the foregoing
specification to the production of sensitive surfaces on paper, glass or other material
to be used for the production of photographic images either by development or
printing out.
Dated this 15th day of August 1888.