Improvements in Photographic Developers.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
:
Improvements in Photographic Developers.
I, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Buildings,
Chancery Lane, in the County of London, Consulting Engineer and Chartered Patent
Agent, do hereby declare the nature of this invention (as communicated to me from
abroad by The Actien Gesellschaft für Anilin Fabrikation, of Berlin, in the Empire of
Germany, Chemical Manufacturers,) to be as follows:-
In the Specifications No. 5207 of 1889 and No. 25002 of 1893 are described methods
of developing photographic pictures by means of certain naphthalene derivatives.
The best known representative of this class of developers is the a-amido-s-naph
thol-8-sulphonic acid, the so called Eikonogen of commerce.
Since the introduction of these developers derived from the naphthalene series and
of the developers derived from the benzene series, such as rodinal, amidol, metol and
others described in the Specifications of No. 1736 of 1891, No. 4498 of 1892, and
No. 15434 of 1891 it has been repeatedly attempted by several investigators to
discover the relations existing between the developing capability and the chemical
constitution of such developors.
Amongst others A. & E. Lumière tried to establish certain views as to the connec-
tion between the developing properties of aromatic substances and their chemical
constitution (see Eder's. Jahrbuch 1892, page 89; les développateurs organiques par
A. & E. Lumière Paris 1893).
These views however were based much more on presumptions than on precise
experimental results; in fact it was afterwards shewn by several authors that these
views were erroneous and A. & E. Lumière themselves modified their views after-
wards in many cases. (See Eder, Photographische Correspondenz 1893, page 118;
Andresen, Photographische Mittheilungen, Vol. 28, page 286 and 296; Photo-
graphische Correspondenz 1894, page 505 and Bulletin de la Société Française de
Photographie 1898, page 158).
For instance, the diamidonaphthol obtained by reducing martius yellow, which
diamidonaphthol according to Lumière's views ought to be a developer, was found
totally unfit for practical use on account of its great instability and its tendency to
produce fogged plates.
This proves that it is not possible to foresee by means of Lumière's views whether
or not a certain compound could be practically used as a developer.
With regard to such aromatic compounds as contain two or more connected
benzene nuclei as for example, the derivatives of the naphthalene series, A. & E.
Lumière had stated (see Eder's Jahrbuch loc. cit.) that their aforementioned
views are only applicable when the hydroxyl- and amido-groups are contained in the
same nucleus. Nothing however is yet known concerning the developing qualities
of such naphthalene derivatives as possess more than two of the groups mentioned,
distributed in different benzene-nuclei.
My foreign correspondents have now discovered that naphthalene derivatives con-
taining in one nucleus the amido- and hydroxy-group in the same position which
these groups occupy in the Eikonogen (a, amido-s-hydroxyl-s-sulphonic acid)

page_text: and containing also another active group in the second nucleus, are developers like
Eikonogen itself, but are distinguished from it by certain valuable properties.
The somewhat slow action and want of density shown by the developers described
in the Specifications No. 5207 of 1889 and No. 25002 of 1893 when used with sodium
sulphite alone, can thus be much improved by introducing into their second nucleus
another amido-group. Compounds of such constitution are the diamidonaphthol-
sulphonic acids obtained by reducing the azo-dyestuffs derived from a₁-amido-a-
naphthol-8, B-disulphonic acid (acid H), a,-amido-a-naphthol-a, B-disulphonic acid
(acid K) or a-amido-a-naphthol-a-monosulphonic acid (acid $).
These new diamidonaphtholsulphonic acids are represented by the following 1
To further illustrate the process the following examples are given :-
1). 12 gramines of diamidonaphtholdisulphonic acid derived from acid H are
dissolved in 1000 c.cm. of distilled water with addition of 24 grammes of crystallized 1
sodium sulphite.
This solution is used as a developer.
2). 15 grammes of diamidonaphtholdisulphonic acid derived from acid K are
dissolved in 1000 c.cm. of water with addition of 50 grainmes of crystallized sodium
sulphite.
3). 10 grammes diamidonaphtholmonosulphonic acid derived from acid S are.
dissolved in 1000 c.cm. of water with addition of 40 grammes of crystallized
sodium sulphite.
2
ABEL & IMRAY,
Agents for the Applicant.
Improvements in Photographic Developers.
I, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Buildings,
Chancery Lane, in the County of London, Consulting Engineer and Chartered Patent
Agent, do hereby declare the nature of this invention (as communicated to me from
abroad by The Actien Gesellschaft für Anilin Fabrikation, of Berlin, in the Empire
of Germany, Chemical Manufacturers) and in what. manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement: —
In the Specifications No. 5207 of 1889 and No. 25002 of 1893 are described
methods of developing photographic pictures by means of certain naphthalene
derivatives. The best known representative of this class of developers is the
a-amido--naphthol 8-sulphonic acid, the so called Eikonogen of commerce,

page_text: Since the introduction of these developers derived from the naphthalene series and
of the developers derived from the benzene series, such as rodinal, amidol, metol and
others described in the Specifications No. 1736 of 1891, No. 4498 of 1892,
and No. 15434 of 1891 it has been repeatedly attempted by several investigators to
discover the relations existing between the developing capability and the chemical
constitution of such developers.
Amongst others, A. & E. Lumière tried to establish certain views as to the connec
tion between the developing properties of aromatic substances and their chemical
constitution (see Eder's Jahrbuch 1892, page 89, les developpateurs organiques par
A. & E. Lumière Paris 1893).
These views however were based much more on presumptions than on precise
experimental results; in fact it was afterwards shewn by several authors that these
views were erroneous and A. & E. Lumière themselves modified their views afterwards
in many cases. (See Eder, Photographische Correspondenz 1893, page 118;
Andresen, Photographische Mittheilungen, Vol. 28, page 286 and 296; Photo-
graphische Correspondenz 1894, page 505 and Bulletin de la Société Française de
Photographie 1898, page 158).
For instance, the diamidonaphthol obtained by reducing martius yellow, which
diamidonaphthol according to Lumières views ought to be a developer, was found
totally unfit for practical use on account of its great instability and its tendency
to produce fogged plates.
This proves that it is not possible to foresee by means of Lumière's views whether
or not a certain compound could be practically used as a developer.
With regard to such aromatic compounds as contain two or more connected benzene
nuclei as for example, the derivatives of the naphthalene series, A. and E. Lumière
had stated (see Eders Jahrbuch loc. cit.) that their aforementioned views are only
applicable when the hydroxyl- and amilo- groups are contained in the same nucleus.
Nothing however is yet known concerning the developing qualities of such
naphthalene derivatives as possess more than two of the groups mentioned,
distributed in different benzene-nuclei.
My foreign correspondents have now discovered that naphthalene derivatives
containing in one nucleus the amido- and hydroxyl-groups in the same position which
these groups occupy in the Eikonogen (a,-amido- 8₁-hydroxyl- 8-sulphonic acid), and
containing also another active group in the second nucleus, are developers like
Eikonogen itself, but are distinguished from it by certain valuable properties.
The somewhat slow action and want of density shown by the developers described
in the Specifications No. 5207 of 1889 and No. 25002 of 1893 when used with
sodium sulphite alone, can thus be much improved by introducing into their second
nucleus another amido-group.
Compounds of such constitution are the diamido-naphtholsulphonic acids obtained
by reducing the azo-dyestuffs derived from a₁-amido-a-naphthol- B2 B3-disulphonic
(acid H), a-amido-a-naphthol-a₂- 8-disulphonic acid (acid K) or 4-amido-a-naphthol-
a-monosulphonic acid (acid S).
These diamidonaphtholsulphonic acids are represented by the following formule :-

page_text: 1.) 12 grammes of diamidonaphtholdisulphonic acid derived from acid H are
dissolved in 1000 c.cm. of distilled water with addition of 24 grammes of crystallised
sodium sulphite.
This solution is used as a developer.
2) 15 grammes of diamidonaphtholdisulphonic acid derived from acid K are
dissolved in 1000 c.cm. of water with addition of 50 grammes of crystallized sodium
sulphite.
3) 10 grammes diamidonaphtholmonosulphonic acid derived from acid S are
dissolved in 1000 c.em. of water with addition of 40 grammes of crystallized sodium
sulphite.
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:
The herein described process for developing photographic pictures on coatings of
silverchloride, bromide or iodide or any mixtures thereof by treating these coatings in
a developing bath containing any of the diamidonaphtholsulphonic or disulphonic
acids obtained by reducing the azo-dyestuffs derived from a-amido-a-naphthol- By B
disulphonic acid (acid H), a₁-amido-a-naphthol-a-83-disulphonic acid (acid K), or
a-amido-a-naphthol-a-monosulphonic acid (acid Sj.
Dated this 10th day of July 1899.
ABEL & IMRAY,
Agents for the Applicant.