New or Improved Developers for Photographic.
Year: 1891

page_text: Date of Application, 30th Jan., 1891
Complete Specification Lelt, 5th Oct., 1891-Accepted, 7th Nov., 1891
PROVISIONAL SPECIFICATION.
[Communicated from abroad by THE ACTIEN GESELLSCHAFT FÜR
ANILIN FABRIKATION, of Berlin, in the Empire of Germany, Chemical
Manufacturers.]
•
New or Improved Developers for Photographic. Pictures.
1, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Fellow of the Institute of Patent Agents, do hereby declare
the nature of this invention to be as follows:
-
This invention relates to the development of photographic pictures by means of
para-amido-phenol and para-amido-cresol or their chlorine, bromine, iodine, oxy-
and amido-derivatives, or the carbonic and sulphonic acids of para-amido phenol
and para-amido cresol.
As is well known, it is the practice in photography to treat the sensitive plates
(prepared with chloride, bromide, or indide of silver or with mixtures of these)
after their exposure, with developing solutions in order to bring out the images
produced on the plates.
Now my foreign correspondents have found by experiment that the substances
mentioned above are exceptionally suitable for developing photographic pictures,
excelling the developing substances hitherto known by effecting an exceedingly
rapid and energetic development, and consequently these substances are especially
applicable for developing plates after short exposures. The negatives obtained are
clear and well detailed, and have a bluish black colour, which ensures rapid
printing.
The following is an example of the preparation of a stock solution which is not
to be diluted with water until just before its use for development.
30 grammes of metabisulphite of potash and 10 grammes of hydrochloride of
para-amido phenol are dissolved in 100 grammes of distilled water. To this
solution concentrated caustic alkali is slowly added until the precipitate which is
at first formed has just become dissolved again.
The above proportions may however be varied, and for the metabisulphite of
potash may be substituted bisulphite of soda or sulphite of soda.
On immersing a photographic plate in this stock solution diluted, the picture
becomes completely developed and can afterwards be fixed in the usual way.
Dated this 30th day of January 1891.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
New or Improved Developers for Photographic Pictures.
I, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Fellow of the Institute of Patent Agents, 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 :-
This invention relates to the development of photographic pictures by means of
para-amido-phenol and para-amido-cresol or their chlorine, bromine, iodine oxy-
and amido-derivatives, or the carbonic and sulphonic acids of para-amido phenol
and para-amido cresol. As is well known, it is the practice in photography to treat
the sensitive plates (prepared with chloride, bromide or iodide of silver or with

page_text: mixtures of these) after their exposure, with developing solutions, in order to bring
out the images produced on the plates.
My foreign correspondents have found by experiment that the substances
mentioned above are exceptionally suitable for developing photographic pictures,
excelling the developing substances hitherto known by effecting an exceedingly
rapid and energetic development, and consequently these substances are especially
applicable for developing plates after short exposures. The negatives obtained are
clear and well detailed, and have a bluish black colour which ensures rapid
printing.
The new developers can be prepared as developing solutions of two classes,
containing the para-amido-phenol or its equivalents, either in the form of the free
base or as an alkali salt. One such solution consists of 5 parts hydrochloric para-
amido-phenol 50 parts sulphite of soda in crystals 25 parts carbonate of potash, in
1000 parts water.
Another consists of 30 parts meta-bisulphite of potash and 10 parts hydrochloric
para-amido-phenol dissolved in 100 parts of boiling water, to which solution is
slowly added whilst stirring, concentrated caustic soda until the precipitated para-
amido-phenol is just re-dissolved.
For practical use, the solution thus obtained of the sodium para-amido phenol
has to be diluted by adding 5 to 50 parts of water, according as the developer is
required to be strong or weak.
The proportions stated above may be varied; for the meta-bisulphite of potash
may be substituted bisulphite of soda or sulphite of soda, and for the carbonate of
potash may be substituted carbonate of soda or lithium.
On immersing a photographic plate in the solutions prepared as above described
the picture becomes completely developed and can afterwards be fixed in the
usual way.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
A photographic developing solution produced from para-amido-phenol or para
amido-cresol or their derivatives, substantially as set forth.
ABEL & IMRAY,
Agents for the Applicant.