Year: 1897

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Date of Application, 3rd Dec., 1897 Accepted, 12th Feb., 1898
SRAZ
Hotographic Developers.
I, Julius HauffF, 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:-
The paraphenylenediamines have hitherto only been capable of consideration as
photographic developers in the sense of possessing a theoretical interest, inasmuch
as they represent a type of developing material, the capacity of which for develop-
ing purposes depends upon the presence of two of the amido groups which are în
para position to one another; they do not however possess any practical importance
as even with the use of caustic alkalies they have not sufficient developing power
for practical purposes and moreover produce a green veil.
The paraphenylenediamines have only been made of practical importance by
the conversion of the same into alkyl derivatives which even with the alkaline
sulphites powerfully develops photographic pictures securing a fine grain without
green veil.
For the attainment of the necessary power for ordinary copying purposes the
alkylised paraphenylenediamines, notwithstanding the great initial rapidity with
which they act still require a rather long time for the developing.
The solutions do not possess the desired degree of durability and a sensible skin
is very easily injuriously affected.
The carbo-oxylised alkyl derivatives of the paraphenylenediamines (glycines)
act otherwise; they effect a rapid development of the photographic picture with
alkaline sulphites without any colouring of the gelatine and with quite as fine a
grain as the alkylised paraphenylenediamines but with greater density of the silver
precipitate. The alkylic developing solutions can be made in a highly concen-
trated form and possess a degree of durability which has never been attained by
any of the developers in use hitherto.
The advantages presented by the glycines of the alkylised paraphenylenedia-
mines are as follows:-
Greater durability of the solutions rapid developing action even in solutions with
alkaline sulphites and with strong density of the lights high sensibility in relation
to bromide of potassium as a restrainer. The negatives are without any colouring
of the gelatine also by the use of carbonates or caustic alkalies and show a very
fine grain similar to that of wet collodion plates.
The best for use are the alkylparaphenylendiaminglycines of the following
composition

page_text: The following is a good developing solution
1 gr. Dimethyl-p-Amidophenylglycine
5 gr. Sulphite of Sodium
5 gr. Potash
100 gr. Water.
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:
-
The employment of the dialkylglycines of the p-phenylenediamine, p-toluy-
lendiamine, p-xylylendiamine a- naphtylendiamine and a--a naphtylendia-
mine on the development of photographic pictures.
Dated thin Onl
1007
H. GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said Julius Hauff.