Improvements relating to the Development of Photographic Pictures.
Year: 1889

page_text: Date of Application, 26th Mar., 1889
Complete Specification Left, 12th Dec., 1889-Accepted, 25th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements relating to the Development of Photographic
Pictures.
I, MOMME ANDRESEN, of 44 Melchiorstrasse, Berlin, in the Empire, of Germany,
Chemist, do hereby declare the nature of this invention to be as follows:
My invention relates to the development of photographic pictures by means of
diamidonaphthaline, amidonaphthol and dioxynaphthaline as well as their sulpho-
acids.
As is well known in photography it is the practice to treat the sensitive plates
(prepared with chloride, bromide or iodide of silver or with two or all of these salts)
after exposure with a developing solution in order to bring to view the image
produced on the sensitive plate. The developing solution hitherto employed for this
purpose has usually consisted of a solution of oxalate of iron, sulphate of iron or
pyrogallic acid.
Now I have found by experiment that diamidonaphthaline, amidonaphthol and
dioxynaphthaline, as well as their sulpho-acids are exceptionally suitable for developing
photographic pictures produced on the said sensitive plates and give better results
than can be obtained with an alkaline pyrogallol developer and excel the latter by
giving the plates a blue black tint similar to that produced when developing in a bath
of oxalate of iron without in the least colouring the sensitive plate. Moreover my
new developers are more durable in an aqueous alkaline solution than the pyrogallol
developer. I thus obtain the advantages possessed by known developing baths without
their disadvantages.
A developing bath prepared with my naphthol developer in which it is intended to
immerse the sensitive plate after having been exposed for the purpose of producing
a visible picture is, for instantaneous photography, advantageously composed of the
following ingredients:-
-
5 grammes of the herein before described naphthol developer.
15 grammes of sulphite of soda.
250 grammes of distilled water, and
Improvements relating to the Development of Photographic
Pictures.
I, MOMME ANDRESEN, of 44, Melchiorstrasse, Berlin, in the Empire of Germany,
Chemist, 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
C
My invention relates to the development of photographic pictures by means of

page_text: when diamidonaphthaline or its sulphonic acids are used. In the same proportion the
quantity of sulphide of soda can be advantageously increased where alphanaphthol
derivatives, (such as amidoalphanaphthol) or their sulpho-acids as mentioned above,
are used.
The before mentioned 5 grammes "naphthol developer" may be used with any
of the above combinations.
As any one of the "naphthol developers" is suitable for the present purpose, I find
it is not absolutely necessary to restrict myself to the use of only one of the
naphthol developers" for the bath, so that the quantity of "naphthol developer'
to be used refers also to mixtures of the above named "naphthol developers."
After having immersed the photographic plate in this bath till the picture becomes
completely developed it is then fixed in the usual way.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is :-
The process herein described of developing photographic pictures on coatings of
chloride of silver, bromide of silver or iodide of silver or of any two or of all three
of them in combination, such process consisting in treating such coatings in a
developing bath containing diamidonaphthaline, amidonaphthol or dioxynaphthaline
or their sulpho-acids.
Date L 10th
1094.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.