An Improved Self-acting Toning-paper.
Year: 1899

page_text: Date of Application, 30th Sept., 1899
Complete Specification Left, 11th June, 1900-Accepted, 25th Aug.,
1900
PROVISIONAL SPECIFICATION.
An Improved Self-acting Toning-paper.
I, OSCAR RAETHEL, of 26, Adolf Street, Berlin, in the Kingdom of Prussia,
Germany, Photographer, do hereby declare the nature of this invention to be
as follows:-
In self-acting toning papers the soluble salt of gold effected the toning in
the fixing bath. Hitherto chloride has been added to the emulsions partly for
converting the silver salt and partly to influence the tone of the ready picture.
In all cases the gold merely has been employed for the purpose to accomplish
the toning of the picture.
The object of the present application is to provide a paper in which the gold
not only forms the toning ingredient but in which it also carries the picture,
that is to say, the gold assists the manufacture of the picture already before
the toning.
The manufacture of my paper is based upon the knowledge that salt of gold
in conjunction with or in presence of chloride of barium is very sensible to
the action of light, whilst chloride of gold (AnCl) alone is insensible to the
same. My process is executed in the following manner:-
1. I produce two solutions or emulsions sensible to the action of light, the com-
position of both being the following:
1. The emulsion of silver sensible to the light for instance, consists of
400 gr. collodion (3%).
16 gr. nitrate of silver dissolved in 20 gr. of distillated water and 30 gr.
of alcohol,
3 gr. of a chloric salt, f.i. chloride of calcium, lithium, strontium or mag-
nesium dissolved in 20 gr. of water.
3 gr. of an organic acid, as f.i. citric acid dissolved in 20 gr. of alcohol.
2. The gold emulsion sensible to the action of light is produced in the fol-
lowing manner:-
To a solution of 0.1 gr. of chloride of gold (AnCl) dissolved in 100' parts
of ether-alcohol about 5 drops of a solution of 1 gr. chloride of barium in 40 gr.
of alcohol (40%) are added, the whole being thoroughly mixed with about
200 gr. of collodion (3%).
I beg to state that chloride of barium in presence of chloride of gold is easily
and completely soluble in the mixture of ether-alcohol and pure alcohol (40%).
Both solutions remain inactive during about 12 hours and then 80 gr. of the
gold solution are added to the above quantity of ready silver emulsion, the
whole being shaken thoroughly.
The emulsion thus produced and mixed can be employed now and the pictures
after drying are ready for printing.
The pictures copied upon this paper are of redish brown colour and for the
purpose of taking off the silver are placed into water. In this bath that quantity
of the chloride of gold which has not yet been attacked by the light, accom-

page_text: plishes the toning. A repetition of the fixation and of the water bath suffices
to obtain reliable pictures of an intense purple colour.
The before described process with respect to known processes shows the
difference that I produce a gold solution sensible to the action of light by com-
bining the sodium chloride of gold with chloride of barium.
Dated this 30th day of September 1899.
An Improved Self-acting Toning-paper.
I, OSCAR RAETHEL, of 26, Adolf Street, Berlin, in the Kingdom of Prussia,
Germany, Photographer, 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 self-acting toning papers the soluble salt of gold effected the toning in
the fixing bath. Hitherto chloride has been added to the emulsions partly for
chloridating the silver salt and partly to influence the tone of the prepared
picture. In all cases the gold merely has been employed for the purpose to
accomplish the toning of the picture.
The object of the present application is to provide a paper in which the gold
not only forms the toning ingredient but in which it also assists the production
of the picture already before the toning.
The manufacture of my paper is based upon the knowledge that salt of gold
in conjunction with or in presence of chloride of barium is very sensible to
the action of light, whilst chloride of gold (AuCl) alone is insensible to the
same. My process is carried out in the following manner: —
I produce two solutions or emulsions sensible to the action of light, the com-
position of both being the following:
1. The emulsion of silver sensible to the light, for instance, consists of
400 gr. collodion (3%).
16 gr. nitrate of silver dissolved in
20 gr. of distilled water and
30 gr. of alcohol,
5-8 gr. of a chloric salt, for instance chloride of calcium, lithium, stron-
tium or magnesium dissolved in 20 gr. of water,
3 gr. of an organic acid, as for instance, citric acid, dissolved in 20 gr. of
alcohol.
2. The gold emulsion sensible to the action of light is produced in the fol-
lowing manner :-
To a solution of 0.1 gr. of chloride of gold (AuCl) dissolved in 100 parts
of ether-alcohol about 5 drops of a solution of 1 gr. chloride of barium in 40 gr.
of alcohol (40%) are added, and then the whole is thoroughly mixed with about
200 gr. of collodion (3%).
I beg to state that chloride of barium in presence of chloride of gold is easily
and completely soluble in the mixture of ether-alcohol with pure alcohol (40%).
Both solutions remain inactive for about 12 hours and then 80 gr. of the gold
solution are added to the above quantity of prepared silver emulsion, the whole
being shaken thoroughly.

page_text: The emulsion thus produced and mixed can now be employed and the pic-
tures after having been dryed are ready for printing.
The pictures copied upon this paper are of redish brown colour and for the
purpose of toning are placed into water whereby that quantity of the chloride
of gold which has not yet been attacked by the light, acts as a toning medium. A
repetition of the fixation and of the water bath suffices to obtain reliable pic-
tures of an intense purple colour.
The before described process with respect to known processes shows the differ-
ence that I produce a gold solution sensible to the action of light by combining
the salt of gold with chloride of barium.
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:
Process for producing a self-toning photographic emulsion containing gold
consisting of adding the chloride of gold in conjunction with chloride of barium
to the prepared silver emulsion containing no soluble silver salt, substantially
as described.