A Process for Developing Photographic Images.
Year: 1892

page_text: Date of Application, 7th Mar., 1892
Complete Specification Left, 29th Oct., 1892-Accepted, 3rd Dec., 1892
PROVISIONAL SPECIFICATION.
A Process for Developing Photographic Images.
I JULIUS HAUFF of Feuerbach, near Stuttgart, Germany, Manufacturer do
bereby declare the nature of this invention to be as follows:-
In the course of my experiments on substances which may be utilized for the
development of photographic images I have made the discovery that the
o-p-diamidophenol surpasses by far all other substances capable of developing
photographs.
Whereas with the developing organic substances hitherto used it was always
necessary to add thereto caustic or carbonated alkalies, in order to effect the
thorough reduction of the halogen silver which had been exposed to the light, the
diamidophenol develops without carbonated or caustic alkalies, with the aid of
the sulphite of the alkalies in a quite sufficient manner so that the use of carbonated
or caustic alkalies may be entirely dispensed with. If only a very small quantity
of carbonate of soda is added to a solution of muriate of diamidophenol, the
solution acts upon exposed plates with such an energy that the unexposed halogen
silver is likewise reduced and thus the appearance of an extraordinarily powerful
veil or shroud is caused. Further I have discovered that the development can be
delayed by the addition of diluted acids, whereas hitherto bromide of potassium
had to be used under the same circumstances. It is obvious that the use of the
bromides or chlorides of the alkalies is not excluded in this case for if the
proper doses are used the desired results can be successfully obtained with those
substances.
I am well aware that diamidophenol has been already often mentioned and
introduced for the development of photographic images but it has not yet been
properly taken into consideration and appreciated, probably because the product
used did not possess the purity with which I am able to prepare it, or because
experiments with diamidophenol were not made in this direction.
The properties of diamidophenol are thoroughly misapprehended, especially there
is no information as to its extraordinarily great solubility which alone is sufficient
to allow of its being used in the manner before stated.
The particular advantages of this substance are its extraordinary developing
power, its practically unlimited durability and utility, its absolute immunity of
action on the fingers, as well as on the gelatine films, and the fact that ordinary
water can be used therewith.
The developing process is carried on as follows:-A salt of the o-p-diamidophenol
is dissolved in a sufficient quantity of water with a sulphite of the alkalies in the
proportion of 1 of the former to 10 of the latter, and the exposed plate is developed
therewith, further quantities of a sulphite solution being added when a powerful
development is required, and diluted acids or bromide and chloride of potassium
for a weak development.
For ordinary portraits the following recipe will be found to answer the purpose:
0-15 grammes of hydrochlorate of diamidophenol; 45 gr. of sulphite of soda and
60 cub. cent. of water. The action is slowed either with a few drops of a
ten per cent. solution of bromide of potassium or a few cub. cent. of a ten per
ceat. solution of sulphuric acid, strengthened with a sulphite of one of the alkalies.
Concentrated solution may be obviously prepared beforehand and diluted
according to requirements, for instance 5 gr. of hydrochlorate of diamidophenol
and 50 gr. of sulphite of soda may be dissolved in 100 gr. of water and diluted to
the extent of 30 times its volume. A solution of 05 gr. of hydrochlorate of

page_text: diamidophenol,, and 0.5 gr. of sulphite of soda in 100 cub. cent. of water will
properly develop plates which have been too long exposed.
F
Diamidophenol develops according to the above given directions without any
veil or shroud being formed and without colouring the gelatinous film after weeks
of exposure in the light and air the solution with sulphites of the alkalies takes
scarcely a somewhat reddish colour while the solution when mixed with small
quantities of carbonated or caustic alkalies takes a brown colour after about
half an hour.
The feature of novelty is :-
:-
A process for the development of photographic images in layers containing
halogen silver consisting in the use of ten per cent. aqueous solutions of the salts of
pure o-p-diamidophenol and sulphite of the alkalies without the simultaneous
presence of carbonated or caustic alkalies, the action being intensified by a further
addition of sulphite and weakened by an addition of diluted acids or diluted
solutions of bromide or chloride of potassium.
Dated this 7th day of Mauch 1000
H.
GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said J. Hauff.
COMPLETE SPECIFICATION.
A Process for Developing Photographic Images.
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:-
In the course of my experiments on substances which may be utilized for the
development of photographic images I have made the discovery that the o-p-diamido-
phenol surpasses by far all other substances capable of developing photographs.
Whereas with the developing organic substances hitherto used it was always
necessary to add thereto caustic or carbonated alkalies in order to effect the thorough
reductions of the halogen silver which had been exposed to the light, the diamido-
phenol develops without carbónated or caustic alkalies with the aid of the sulphite
of the alkalies in a quite sufficient manner so that the use of carbonated or caustic
alkalies may be entirely dispensed with. If only a very small quantity of carbonate
of soda is added to a solution of muriate of diamidophenol, the solution acts upon
exposed plates with such an energy that the unexposed halogen silver is likewise
reduced and thus the appearance of an extraordinarily powerful veil or shroud is
caused. Further I have discovered that the development can be delayed by the
addition of diluted acids whereas hitherto bromide of potassium had to be used under
the same circumstances. It is obvious that the use of the bromides or chlorides of
the alkalies is not excluded in this case for if the proper doses are used the desired
results can be successfully obtained with those substances.
I am well aware that diamidophenol has been already often mentioned and
introduced for the development of photographic images but it has not yet been
properly taken into consideration and appreciated probably because the product
used did not possess the purity with which I am able to prepare it, or because
experiments with diamidophenol were not made in this direction.
The properties of diamidophenol are thoroughly misapprehended, especially there
is no information as to its extraordinarily great solubility which alone is sufficient to
allow of its being used in the manner before stated.
The particular advantages of this substance are its extraordinary developing
power, its practically unlimited durability and utility its absolute immunity of
action on the fingers, as well as on the gelatine films, and the fact that ordinary
water can be used therewith.

page_text: The developing process is carried on as follows: -A salt of the o-p-diamidophenol
with a sulphite of the alkalies in the proportion of 1 of the former to 10 of the
latter is dissolved in a sufficient quantity of water and the exposed plate is developed
therewith, further quantities of a sulphite solution being added when a powerful
development is required and diluted acids or bromide and chloride of potassium for
a weak development.
For ordinary portraits the following recipe will be found to answer the purpose:
0-45 grammes of hydrochlorate of diamidophenol, 4-5 gr. of sulphite of soda and
60 cub. cent. of water. The action is slowed either with a few drops of a ten per cent.
solution of bromide of potassium or a few cub. cent. of a ten per cent. solution of
sulphuric acid strengthened with a sulphite of one of the alkalies.
Concentrated solution may be obviously prepared beforehand and diluted
according to requirements, for instance 5 gr. of hydrochlorate of diamidophenol
and 50 gr. of sulphite of soda may be dissolved in 100 gr. of water and diluted to
the extent of 30 times its volume. A solution of 0.5 gr. of hydrochlorate of
diamidophenol and 5 gr. of sulphite of soda in 100 cub. cent. of water will properly
develop plates which have been too long exposed.
Diamidophenol develops according to the above given directions without any
veil or shroud being formed and without colouring the gelatinous film; after weeks
of exposure in the light and air the solution with sulphites of the alkalies takes
scarcely a somewhat reddish colour while the solution when mixed with small
quantities of carbonated or caustic alkalies takes a brown colour after about half
an hour.
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 1
claim is :-
A process for the development of photographic images in layers containing halogen
silver consisting in the use of aqueous solutions of a salt of the pure o-p-diamido-
phenol and a sulphite of the alkalies in the proportion of 1 of the former to 10 of
the latter without the simultaneous presence of carbonated or caustic alkalies, the
action being intensified by a further addition of sulphite and weakened by an
addition of diluted acids or diluted solutions of bromide or chloride of alkalies.
Lato1 $1519 VALIDAT
H.
GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said J. Hauff.
Loto 21 VA
H. GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said J. Hauff.