IMPROVEMENTS IN PHOTOGRAPHIC AND OTHER CHEMICAL PRINTING
Year: 1881

page_text: "
LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of IMPROVEMENTS
IN PHOTOGRAPHIC AND OTHER CHEMICAL PRINTING." A communication
from abroad by Louis Corbassière dit Christian, and Alphonse Liébert, both
of Paris, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 1st January 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. " IMPROVEMENTS IN PHOTOGRAPHIC AND OTHER
CHEMICAL PRINTING." [A communication from abroad by Louis Corbassière dit
Christian, and Alphonse Liébert, both of Paris, France.]
This Invention relates, 1st, to a process of photographic and other chemical
printing, yielding the same warm tints as are obtained by the photographic papers
in ordinary use, capable of being worked without the aid of light, and enabling a
very great number of prints to be obtained in a practical, rapid, and certain way
from a photographic or other negative, and upon any surface, whatever may be the
substance employed.
Since the art of photographing on paper was first introduced it has been a
desideratum to be able to rapidly produce the prints with the warmth of tint in
vogue, and the albumenized paper generally used gives the best results, but slowly,
and its cost is considerable.
The carbon process is complicated, involves delicate manipulation, and the image
is with difficulty brought to the desired sharpness.
Prints in salts of iron, uranium, palladium, platinum, &c., are cold and disagreeable
in tone, and as to the mode of printing by transfer of collodion or other films it is
very expensive, and has been practically abandoned.
This improved process is designed to combine economy, rapidity, simplicity,
beauty of tint, and permanence of result.

page_text: The process can be carried out in practice in different ways, and I will describe
two examples of its mode of application to paper.
1st Method. The process gives as final result an image formed of metallic
oxides enclosed in an impermeable substance, the method of procedure being as
follows:-
(1st.) A mixture of a suitable binary or tertiary compound of silver, which must
be insoluble in water, is added in very small quantity to the paper pulp by any
suitable mechanical or chemical means; or (2nd) this compound may be applied
to the surface of the paper, but in this case it would be incorporated in vehicles,
such as fermentable, starchy, nitrogenized matters, which may even contain
sulphur in a latent form, or organic or organized matters, hydrocarbons or their
derivatives, fatty matters, with or without metallic oxides. The resulting mixture
may be applied either by immersion, with the brush, by rollers, or in any other.
suitable way; or (3rd) a thick layer may be prepared, as hereafter explained.
The process of producing the image is the same whichever of the above ways of
obtaining the sensitive surface or layer may be employed.
This process consists in the apposition upon this surface or layer of the negative.
with the varnished side downwards; the fermentation, which sets up or has been
caused to set up in the mass, determines the greater or less rapidity of the printing
when the whole is exposed to the most feeble light. It is therefore necessary that
all the preceding operations should be performed in the dark room.
•
In certain cases the simple addition of ammonia is sufficient to develop the image.
In most cases it is better to employ. reducing agents which develop the image
slowly, so that the development may be arrested when the desired strength is
attained, as in any case it will remain as it was developed when all the operations
are terminated.
To obtain the photographic tint in vogue it is necessary after washing to immerse
the print a short time in a bath composed of sulphuric acid, sulpho-cyanide of
potassium, protochloride of tin, and fermented albumen. The protochloride of tin
may be replaced by numerous other metallic salts, which alone or in conjunction
with the composition before described produce the same result. On leaving this
bath the print is washed, and passed through a second bath composed of a suitable
base, which gives according to its nature the tint desired, black, warm black,
brownish red, green, blue, yellow, &c., &c. Another washing completes the
process. A metallic oxide is thus chemically produced, which is unalterable by
the air.
2nd Method. A layer or surface of sensitive material prepared as in the
preceding method is exposed beneath the negative, varnished side downwards, to
the most feeble light, and the image appears as above described, but the subsequent
operations are different.
By this 2nd method a number of prints may be in fact obtained without again
having recourse to even the most feeble light. The image when finished, as herein-
before directed, is covered with a sheet of paper impregnated with a substance
capable of rendering soluble the metallic substance contained in the mass, nitric
acid, for example.
This paper may be of any suitable composition, or woven fabric may be used
instead. After a few moments it is removed, and replaced by other sheets of paper
or fabric, coated or impregnated with proto-chloride of tin or other substance
producing the same result. It is only necessary to apply a slight pressure to each
of the several sheets to obtain as many prints.
These sheets of paper or fabric are immersed together in a bath composed of a
base, which differs according to the tint to be obtained, washed, dried, albumenized,
or varnished, according as the prints are to be dead or glazed.
The process may be applied upon wood, cloth, silk, or other fibrous fabrics or
tissues, in the same way as above described for paper.
In certain cases when desired to produce the impression upon metals inferior to
silver, marble, or other analogous substances, the surface of the material must first

page_text: be coated with a varnish not attacked by acids, such as found ordinarily in
commerce; the other operations are performed as above described.
Lastly. If it be desired to obtain white prints on colored substances an inert
matter (sulphate of baryta, for example) is added mechanically or chemically to the
sensitive material, which gives a white ground that may be tinted rose color if
desired with an inert rose colored substance. The subsequent operations are the
same as above described.
In the case of enlargements the layer or surface is prepared in the usual way, as
herein before described, and an enlarging camera of the most simple kind is used,
illuminated by feeble light, and the print and the tint are obtained as above
described.
The Invention thus consists, first, in the process of photographic and other
chemical printing, producing the warm tints obtained by the photographic papers
in ordinary use, and capable of being performed with or without the use of light by
means of the substances and methods above described, whereby a very great
number of prints may be obtained in a practical, rapid, and certain manner, from a
photographic or other negative, upon any suitable surface, as above set forth.
I have described the different means of producing photographic prints from a
negative, but the sensitive material of this Invention enables the direct production
(in the camera, and without having recourse to a negative) of white prints upon a
black ground.
To this end I prepare, as above described, a substance composed of a salt of silver
absolutely insoluble in water, and of a suitable organic or organized matter, and
apply it to paper colored according to the tint which it is desired to obtain.
The paper is placed in a moist or dry state upon a glass plate, and then exposed
in the camera for a very short period. I then develop the image by one of the
known reducing agents, and then fix by hyposulphite of soda or other solvent for
salts of silver. After washing for a few minutes the print is immersed in a bath
composed of a salt of mercury soluble in water (per salt of mercury), with the
addition of a few drops of hydrochloric acid. The image is immediately developed
white on a colored ground. The print thus obtained is reversed; to set it right the
mode of double transfer may be adopted as ordinarily practised in the carbon
process.
The print when dry is trimmed, sized with paste slightly acidulated with
hydrochloric acid, and varnished. It may also be enamelled in the ordinary way.
The Invention therefore comprises, secondly, the application of the sensitive
substance herein described to the direct production, without the use of a negative,
of white prints on black or colored grounds, as above specified. .

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
1st July 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN PHOTOGRAPHIC AND OTHER
CHEMICAL PRINTING." A communication from abroad by Louis Corbassière dit
.Christian and Alphonse Liébert, both of Paris, France.
This Invention relates, 1st, to a process of photographic and other chemical
printing, yielding the same warm tints as are obtained by the photographic
papers in ordinary use, capable of being worked without the aid of light, and
enabling a very great number of prints to be obtained in a practical, rapid, and
certain way from a photographic or other negative, and upon any surface whatever
may be the substance employed.
Since the art of photographing on paper was first introduced, it has been a
desideratum to be able to rapidly produce the prints with the warmth of tint in
vogue, and the albumenised paper generally used gives the best results, but
slowly, and its cost is considerable. The carbon process is complicated, involves
delicate manipulation, and the image is with difficulty brought to the desired
sharpness. Prints in salts of iron, uranium, palladium, platinum, &c., are cold and
disagreeable in tone, and as to the mode of printing by transfer of collodion or
other films, it is very expensive and has been practically abandoned.
This improved process is designed to combine economy, rapidity, simplicity,
beauty of tint, and permanence of result. The process can be carried out in
practice in different ways, and I will describe two examples of its mode of
application to paper.
1st Method. The process gives as final result an image formed of metallic oxides
enclosed in an impermeable substance, the method of procedure being as follows:-
(1st.) A mixture of a suitable binary or tertiary compound of silver, which must
be insoluble in water, is added in very small quantity to the paper pulp by any
suitable mechanical or chemical means.
(2nd.) This compound may be applied to the surface of the paper, and the
following is the composition of the emulsion to be employed to sensitize the paper
or other substance :-
Gelatine (dialysed)
Water (undistilled)
-
-
135 grammes.
1 litre.
The gelatine is allowed to soak for 24 hours and then heated to 30° C. to melt
the same.
To one half of this solution is added albumen which has fermented for
•
3 days in
Albumen which has fermented for 3 days in 30 grammes of water
Antimoniate of potash
I also dissolve anant
-
Grammes.
2.5
0.65.

page_text: brush, or by means of rollers. If it be desired that the film should have a glossy
surface, a suitable quantity of varnish insoluble in water may be added to the
emulsion, or the paper used may have been previously coated with albumen
rendered insoluble, or any kind of paper with a glossy surface may be used.
Or (3rd) a thick layer of this emulsion may be prepared, as hereafter explained.
The process of producing the image is the same whichever of the above ways of
obtaining the sensitive surface or layer may be employed.
This process consists in the apposition upon this surface or layer of the negative
with the varnished side downwards; the fermentation which sets up or has been
caused to set up in the mass determines the greater or less rapidity of the printing
when the whole is exposed to the most feeble light. It is therefore necessary that
all the preceding operations should be performed in the dark room.
The development of the image after printing is preferably obtained by the
employment of a mixture of acidulated sulphate of iron and neutral oxalate of
potassa; in any case it will remain as it was developed after all the operations are
terminated.
The photographic tint which ranges from red to blue-black is most readily
obtained by causing the primitive image, which is of a greenish color, to disappear
by dipping it for a few moments in a bath composed of bichloride of mercury,
bichloride of tin, and sulphuric acid, in varying proportions according to the tint
required, and then reviving the image by placing it in an aqueous solution of soda.
lime, to which is added, if desired, and according to the color required, a small
quantity of ammonia, borax, and chloride of gold or platinum, or other metallic
salts.
2nd Method. A layer or surface of sensitive material, prepared as in the
preceding method, is exposed beneath the negative, varnished side downwards, to
the most feeble light, and the image appears as above described, but the subsequent
operations are different.
By this second method a number of prints may be in fact obtained without
again having recourse to even the most feeble light. The image when finished, as
herein before directed, is covered with a sheet of paper impregnated with a substance
capable of rendering soluble the metallic substance contained in the mass, nitric
acid, for example. This paper may be of any suitable composition, or woven fabric
may be used instead. After a few moments it is removed and replaced by other
sheets of paper or fabric coated or impregnated with protochloride of tin or other
substance producing the same result. It is only necessary to apply a slight
pressure to each of the several sheets to obtain as many prints. These sheets of
paper or fabric are immersed together in a bath composed of a base which differs
according to the tint to be obtained, washed, dried, albumenised, or varnished,
according as the prints are to be matt or glazed.
The process may be applied upon wood, cloth, silk, or other fibrous fabrics or
tissues in the same way as above described for paper. In certain cases when
desired to produce the impression upon metals inferior to silver, marble, or other
analogous substances, the surface of the material must first be coated with a
varnish not attacked by acids, such as found ordinarily in commerce; the other
operations are performed as above described.
Lastly. If it be desired to obtain white prints on colored substances an inert
matter (sulphate of baryta, for example) is added mechanically or chemically to the
sensitive material, which gives a white ground that may be tinted rose color, if
desired, with an inert rose colored substance. The subsequent operations are the
same as above described.
In the case of enlargements the layer or surface is prepared in the usual way as
herein before described, and an enlarging camera of the most simple kind is used,
illuminated by feeble light, and the print and the tint are obtained as above
described.
I have described the different means of producing photographic prints from a
negative, but the sensitive material of this Invention enables the direct production

page_text: (in the camera and without having recourse to a negative) of white prints upon a
black ground. To this end I prepare an emulsion for sensitizing the paper, as
above described, and apply it to paper colored according to the tint which it is
desired to obtain. The paper is placed in a moist or dry state upon a glass plate
and then exposed in the camera for a very short period. I then develop the image
by one of the known reducing agents and fix by hyposulphite of soda or other
solvent for salts of silver. After washing for a few minutes the print is immersed
in a bath composed of a salt of mercury, soluble in water (per salt of mercury), with
the addition of a few drops of hydrochloric acid. The image is immediately
developed white on a colored ground. The print thus obtained is reversed; to set
it right the mode of double transfer may be adopted, as ordinarily practised in the
carbon process.
The print when dry is trimmed, sized with paste slightly acidulated with
hydrochloric acid, and varnished. It may also be enamelled in the ordinary
way.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is,―
1st. The herein described processes for the preparation of paper or other
surfaces, either matt or glazed, of extreme sensitiveness and capable of receiving
images of great sharpness; and for the transformation of the greenish black tint of
the said image to a color varying from red to blue-black, similar to those produced
on albuminised paper.
2nd. The application of the improved sensitive composition herein described to
the direct production, without the use of a negative, of white prints upon a black
or colored ground, as specified.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this First day of July, A.D. 1881.