The Employment of Diamidodioxybenzol in Combination with Sulphites of the Alkalies for Developing the Latent Image in Layers containing Halogen Silver for Photographic Purposes.
Year: 1892

page_text: Date of Application, 8th Dec., 1892
Complete Specification Left, 14th June, 1893-Accepted, 22nd July, 1893
PROVISIONAL SPECIFICATION.
The Employment of Diamidodioxybenzol in Combination with
Sulphites of the Alkalies for Developing the Latent Image in
Layers containing Halogen Silver for Photographic Purposes.
I JULIUS HAUFF of Feuerbach, near Stuttgart, Germany, Manufacturer do
hereby declare the nature of this invention to be as follows:-
This invention relates to the employment of diamidodioxybenzol for developing
the latent image in layers containing halogen silver for photographic purposes
consisting in dissolving in suitable proportions in water diamidodioxybenzol with
soluble sulphites or with soluble acid sulphites and with the addition of the quantity
of soluble bases or carbonates required for the purpose of neutralization, so as to
obtain solutions ready for developing purposes, the action of these solutions being
intensified by the addition of a few drops of preferably a 5% solution of a
carbonate of the alkalies and enfeebled like other photographic developing
substances by the addition of a few drops of an acid solution or of a few drops of
a solution of bromide of potassium.
The ortho-amido compounds of phenol and cresol have not yet been utilized for
photographic purposes, nor have they been as yet included in patents referring to
such purposes.
Without the use of caustic or carbonated alkalies they are too.
weak bodies for covering purposes in order to bring out the latent image, while if:
such chemicals are used they are too energetic as reducing means and impart a black.
colour to the whole image.
As a result of my experiments on the preparation of such developing substances:
which develop the image in weak acid or neutral solutions I have discovered that
by introducing another amido group in amido phenols which only operate in alkaline
solutions, these amido-phenols will be able to develop with sulphites only and that.
my views were capable of the most extensive generalisation. The chief
representative of this new group of developing substances is the already patented
diamidophenol which gave me, since the short time that it has made its appearance
in the market, the most conclusive proof of its sterling properties for developing
purposes. The theoretical testing of other substances under consideration led me
to the thought that by doubling the OH, NH, = 1:2 group in the benzol kernel,.
I may be able to likewise double the developing power, which is not very great, of
the above mentioned orthoamido compounds for developing with carbonates of the
alkalies so that the said orthoamido compounds may be able to develop the image.
with sulphites only. In testing these orthoamido compounds substances of the
following constitution presented themselves in the first place.
5 that is to say diamidodioxybenzol with two hydroxylamido groups existing together
in the ortho arrangement. As a matter of fact this compound is a very advantageous
developing means which without the use of caustic or carbonated alkalies slowly
develops the latent image in from 3 to 4 minutes with a deep coating and fine
details or outlines. It develops much more slowly than the diamidophenol
0 developing agent a fact which may be already expected from the other grouping of
the developing radicals; for many purposes however this is a distinct advantage over

page_text: the diamidophenol developing agents to which I have given in commerce the name of
amidol. Moreover the new developing means unite the advantage of the dihydrooxyl
developing means i.e. a deep black colour and covering with the advantage of the
hydroxylamido developing means that is to say clear work sharply outlined in all
its details and entirely free from mist or haze without requiring the use of caustic 5
or carbonated alkalies which are injurious at many points of view.
EXAMPLE.
In 100 parts of water I dissolve 0.5 parts of diamidodihydroxybenzol and 8 parts
of crystallized sulphite of soda. With this solution several successive developments
may be effected. To intensify this development I may use a concentrated solution 1
of a sulphite or a few drops of a 5% solution of bromide of potassium may be used.
To obtain greater durability for the solution I may use instead of a neutral
sulphite an acid sulphite of soda, only it would be necessary in such a case to add
before developing the required quantity of a base or of a carbonate to neutralize
the double sulphite of soda.
Dal 01 1
2003
1
H. GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said J. Hauff.
COMPLETE SPECIFICATION.
The Employment of Diamidodioxybenzol in Combination with
Sulphites of the Alkalies for Developing the Latent Image in
Layers Containing Halogen Silver for Photographic Purposes.
I, JULIUS HAUFF, of Feuerbach, near Stuttgart, Germany, Manufacturer, 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 employment of diamidodioxybenzol for developing
the latent image in layers containing halogen silver for photographic purposes
consisting in dissolving in suitable proportions in water diamidodioxybenzol with
soluble sulphites, or with soluble acid sulphites to which latter is added the quantity
of soluble bases or carbonates required for the purpose of neutralization, so as to
obtain solutions ready for developing purposes, the action of these solutions being
intensified by the addition of a few drops of preferably a 5% solution of a
carbonate of the alkalies and enfeebled by the addition of a few drops of an acid
solution, or of a few drops of a solution of bromide of potassium.
The ortho-amido compounds of the phenols and cresols have not yet been
utilized as developing substances for photographic purposes, nor have they been as
yet included in patents referring to such purposes.
Without the use of caustic or carbonated alkalies they are too weak bodies for
reduction purposes in order to bring out the latent image, while if such chemicals
are used they are too energetic as reducing means, and impart a black colour to
the whole image.
As a result of my experiments on the preparation of such developing substances
which develop the image in weak acid or neutral solution, I have discovered that
by introducing a further amido group in amido phenols which only operate in
alkaline solutions, these amido-phenols will be able to develop with sulphites only,
and that my opinion is capable of the most extensive generalisation. The chief
representative of this new group of developing substances is the already patented
diamidophenol which gave me since the short time that it has made its appearance
in the market, the most conclusive proof of its sterling properties for developing
purposes. The theoretical testing of other substances under consideration led me
to the thought that by doubling the OH: NH2 = 1:2 group in the benzol kernel
I may be able to likewise double the developing power which is not very great, if
==

page_text: the above mentioned orthoamido compounds are employed for developing without
carbonates of the alkalies, so that the said orthoamido compounds may be able to
develop the image with sulphites only. In testing these orthoamido compounds,
the substance of the following constitution presented themselves in the first
that is to say a diamidodioxybenzol with two hydroxylamido groups existing
together in the ortho arrangement. As a matter of fact, this compound is a very
advantageous developing means which without the use of caustic or carbonated
alkalies slowly develops the latent image in from 3 to 4 minutes with a deep coating
and fine details or outlines. It develops much more slowly than the diamidophenol
developing agent, a fact which may be already expected from the other grouping
of the developing radicals: for many purposes however this is a distinct advantage
over the diamidophenol developing agent to which I have given in commerce the
name of amidol. Moreover the new developing means unites the advantage of the
dihydroxyl developing means i.e. a deep black colour and covering with
the advantage of the hydroxylamido developing means, that is to say, clear work
sharply outlined in all its details and entirely free from mist or haze without
requiring the use of caustic or carbonated alkalies which are injurious at many
points of view.
EXAMPLE.
In 100 parts of water I dissolve 0.5 parts of diamidodihydroxybenzol and 8 parts
of crystallized sulphite of soda. With this solution, several successive developments
may be effected. To intensify this development, I may use a concentrated solution
of a sulphite, or a few drops of a 5% solution of potash in water, whereas to retard
the development, a few drops of an acid, or of a 5% solution of bromide of
potassium may be used.
To obtain greater durability for the solution, I may use instead of a neutral
sulphite, an acid sulphite of soda, only it would be necessary in such a case to add
before developing the required quantity of a base, or of a soluble carbonate to
neutralize the double sulphite of soda.
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 employment of diamidodioxybenzol for developing the latent image in layers
containing halogen silver for photographic purposes consisting in dissolving in
suitable proportions in water diamidodioxybenzol with soluble sulphites, or with
soluble acid sulphites, to which latter is added the quantity of soluble bases or
carbonates required for the purpose of neutralization, so as to obtain solutions ready
for developing purposes, the action of these solutions being intensified by the
addition of a few drops of preferably a 5% solution of a carbonate of the alkalies,
and enfeebled by the addition of a few drops of an acid solution, or of a few drops
of a solution of bromide of potassium.
The 14+1 der of Lune 1893
H. GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said Julius Hauff.