Improvements in Photographic Developing Solutions.
Year: 1892

page_text: Date of Application, 5th Oct., 1892
Complete Specification Left, 4th July, 1893-Accepted, 5th Aug., 1893
PROVISIONAL SPECIFICATION.
Improvements in Photographic Developing Solutions.
I, RUPERT GREVILLE WILLIAMS, of Greenfield House, Heywood, Manchester,
Lancashire, Manufacturing Chemist, do hereby declare the nature of this invention
to be as follows:-
My invention relates to improvements in photographic developing solutions, the
object of such improvements being (by the addition of certain hereinafterwards
described bodies to the developer) the elimination of actinic rays from the plate
under development when such development is carried out in dark rooms (or other
places) that are not sufficiently "light tight," and would by such reason become
fogged" if the usual developers were employed without the addition of such
bodies.
In carrying the invention into effect, I mix the sodium, potassium or ammonium
compounds of rosolic acid with the developing solution in about the proportion of
25 parts of a one per cent. solution of the compound of rosolic acid to 250 parts
of the developing solution.
By the use of developers which have had the above compounds added to them,
the development may be carried out in an ordinary room by gas light. While the
plate is being removed from the dark-slide to the developing tray, the gas should
be lowered, but as soon as the plate is submerged, it can be raised again and the
progress of the operation observed without injury to the negative from "fogging."
The developing case described in an application for Letters Patent of an even
date herewith is one in which the present invention can be used even in broad
daylight with especially advantageous results.
When a plate which has been developed by means of my improved developing
solution is removed from the hyposulphite bath, it will be found that the gelatine
film is stained red by reason of the adhesion of a portion of the rosolic acid alkaline
salt to it. The treatment of the plate with the usual alum solution, to harden the
film, has the effect of causing the red stain to disappear. Free rosolic acid,
however, is still present on the film, but this can (after the plate has been a sufficient
length of time in the alum bath) be easily and safely removed by soaking the plate
for a few minutes in water made slightly alkaline by the addition of a little sodium
carbonate, ammonium carbonate, potassium carbonate or ammonia solution. The
film will turn pink or red again as soon as it enters this alkaline bath, but the
latter will soon dissolve out the rosolic acid, leaving the plate clean. It is advisable,
however, to again pass it through a solution of alum before the final washing.
Phenol-phthaleine or any other suitable yellow to red colouring matter which is
soluble in alkalies may be used instead of rosolic acid.
These compounds should be added to the developing solution immediately before
use, and should not be added to any of the separate ingredients forming the
developer.
Dated this 4th day of October 1892.
PHILLIPS & LEIGH,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Photographic Developing Solutions.
I, RUPERT GREVILLE WILLIAMS, of Greenfield House, Heywood, Manchester,
Lancashire, Manufacturing 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:-
My invention relates to improvements in photographic developing solutions, the
object of such improvement being (by the addition of certain herein-afterwards
described bodies to the developer). the elimination of actinic rays from the plate
under development when such development is carried out in dark rooms (or other
places) that are not sufficiently "light-tight" and which plate would by such
reason become "fogged" if the usual developers were employed without the
addition of such bodies.
In carrying the invention into effect, I mix the sodium, potassium or ammonium
compounds of rosolic acid with the developing solution in about the proportion of
25 parts of a one per cent. solution of the compound of rosolic acid to 250 parts of
the developing solution.
By the use of the developers which have had the above compounds added to
them, the development may be carried out in an ordinary room by gaslight. While
the plate is being removed from the dark slide to the developing tray, the gas
should be lowered as far as possible, but as soon as the plate is submerged, it can
be raised again and the progress of the operation observed without injury to the
negative from "fogging."
When a plate which has been developed by means of my improved developing
solution, is removed from the hyposulphite fixing bath, it will be found that the
gelatine film is stained red by reason of the adhesion of a portion of the rosolic
acid alkaline salt to it. The treatment of the plate with the usual alum solution
to harden the film, has the effect of causing the red stain to disappear. Free
rosolic acid, however, is still present on the film, but this can (after the plate has.
been a sufficient length of time in the alum bath) be easily and safely removed by
soaking the plate for a few minutes in water made slightly alkaline by the addition
of a little sodium carbonate, ammonium carbonate, potassium carbonate or ammonia
solution. The film will turn pink or red again as soon as it enters this alkaline
bath, but the latter will soon dissolve out the rosolic acid, leaving the plate clean.
It is advisable however, to again pass it through a solution of alum before the
final washing.
Phenol-phthaleine or any other suitable yellow to red colouring matter which is
soluble in alkalies, and does not dye the film, may be used instead of rosolic acid.
These compounds should be added to the developing solution immediately before
use, and should not be added to any of the separate ingredients forming the
developer.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
elain is :-
1. The herein before described process for the elimination of actinic light rays
from photographic plates during the process of development.
2. The combination of rosolic acid salts with a developing, solution as set forth.
3. The combination with a developing solution of any of the hereinbefore
mentioned substances for the purpose specified.
of 1002
PHILLIPS & LEIGH,
22, Southampton Buildings, Chancery Lane, W.C.,
Agents for the Applicant.
PHILLIPS & LEIGH,
22, Southampton Buildings, Chancery Lane, W.C.,
Agents for the Applicant.