Improvements in the Process of Making Photographic Films.
Year: 1893

page_text: Date of Application, 28th Sept., 1893
Complete Specification Left, 7th June, 1894-Accepted, 14th July, 1894
PROVISIONAL SPECIFICATION.
Improvements in the Process of Making Photographic Films.
A communication to me from RICHARD REISSNER, Doctor of Medicine, and
GUSTAV CHRISTIAN FÜRCHTEGOTT HAUSER, Doctor of Philosophy and
Medicine, and Professor, both of Erlangen, Bavaria, in the Empire of
Germany.
I, EDMUND EDWARDS, of the Firm of Edwards and Co., Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of
Middlesex, do hereby declare the nature of this invention to be as follows:-
--
This invention relates to improvements in the process of making films or
dryplates for photographic purposes and especially that kind of films which are
made from gelatine containing bromide of silver.
The object of the improvement which forms the subject of the present invention
is to so treat the films that they can neither be liquefied by immersing them in
warm water after having been dried, nor can they be caused to do so by drying
them in a warm room after they have been wetted. The gelatine films which have
been used until now are imperfect inasmuch as they frequently liquefy during the
developing, fixing, washing, and drying, in cases where these manipulations are
carried on during warm weather or in southern countries. It is obvious that the
film must be rendered useless when this takes place.
According to the present invention the gelatine to be used in the manufacture of
films is rendered insoluble by the action of formylaldehyd (CH₂O) to such a degree
that the film may be immersed in water of 122° F., or may be dried in a room the
temperature of which is the same, without any danger of its liquefying.
It has been found in practice that a satisfactory result is obtained if the film is
immersed in a solution of one per cent. of formylaldehyd in water, and it is
preferable to treat in this manner the usual films of gelatine containing bromate of
silver.
The films are afterwards washed carefully, dried, and then treated in the usual
manner.
COMPLETE SPECIFICATION.
Improvements in the Process of Making Photographic Films.
A communication to me from RICHARD REISSNER, Doctor of Medicine, and
GUSTAV CHRISTIAN FÜRCHTEGOTT HAUSER, Doctor of Philosophy and
Medicine, and Professor, both of Erlangen, Bavaria, in the Empire of
Germany.
I, EDMUND EDWARDS, of the Firm of Edwards and Co., Patent Agents and
Engineers, of 65 and 66, Chancery Lane, in the County of Middlesex, 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, that is to say :-
This invention relates to improvements in the making of films or dry plates for

page_text: photographic purposes, and especially the kind of films which are made from
gelatine containing bromide of silver.
The object of the improvement which forms the subject of the present invention
is to so treat the films that they can neither be liquefied by immersing them in
warm water, after having been dried, nor can they be caused to do so by drying
them in a warm room after they have been wetted. The gelatine films which have
been used until now are imperfect inasmuch as they frequently liquefy during the
processes of developing, fixing, washing, and drying, in cases where these
manipulations are carried on during warm weather or in hot southern countries.
It is obvious that the films must be rendered useless when this occurs.
According to the present invention, the gelatine to be used in the manufacture of
films is rendered insoluble by the action of formaldehyd, (CH₂O) to such a degree,
that the film may be immersed in water of 122° Fahrenheit, or may he dried in a
room having the same temperature, without any danger of its liquefying.
It is obvious that in some cases it may be useful to treat in the same manner
films or sheets of gelatine used for other technical purposes as well as photographic
ones.
The improved process is as follows:-
It
The formaldehyd is dissolved in water, that is to say, preferably 0-2 parts of
gelatine in 100 parts of water. The gelatine is then added to this solution.
may be mentioned that 0.2 parts of formaldehyd are able to render insoluble
10 part of gelatine. The gelatine may remain in the solution for one or two
hours. Films of less thickness will be permeated sooner. The gelatine may be
added to the solution in a dry state, or it may be added after it has been
liquefied.
The gelatine is then formed into sheets or films if this had not been previously
done, and it is dried in the air. The forming into films is preferably done by
spreading the gelatine upon plates of glass or metal, the surface of which has been
polished.
As the rendering insoluble of the films is effected during the drying process, it
may be mentioned, that the gelatine must not be washed after having been taken
from the solution.
It is obvious that instead of making use of the formaldehyd itself, the component
parts by the mutual influence of which such formaldehyd is composed and
produced may themselves be used.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is :-
1. A process for rendering insoluble in hot water films consisting of gelatine, by
treating them with a solution of formaldehyd, substantially as described.
2. A process for rendering insoluble in hot water, films consisting of gelatine by
treating them with a solution of the component parts by the mutual influence of
which upon each other formaldehyd is generated.
Dated this 7th day of June 1894.
EDWARDS & Co.,
65 & 66, Chancery Lane, London, Agents for the Applicant.