IMPROVEMENTS IN PRODUCING CARBON PHOTOGRAPHS
Year: 1874

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN PRODUCING CARBON PHOTOGRAPHS."-A communication
from abroad by Claude Léon Lambert, of Paris, France.
Sealed the 6th April 1875, and dated the 21st October 1874.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 21st October 1874.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County
of Middlesex, Patent Agent, do hereby declare the nature of the said
Invention for “IMPROVEMENTS IN PRODUCING CARBON PHOTOGRAPHS," to be as
follows:
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This Invention relates to the production of carbon photographs with
salts of chromium and therefore permanent, involving less than half
the labor necessary when salts of silver are used, the picture being non-.
reversed and gelatinized at the same operation., I take a glass plate and
apply a greasy coating, and upon this a film of normal collodion, and

page_text: then immerse the plate in cold water. I then remove from their presses
the prepared papers and apply one on the glass coated as described,
while it is still in the bath and remove both together and subject them
to slight pressure for some minutes. I then immerse in warm water and
I devalope the positive picture, which according to the length of exposure
may be seen either by transmitted or reflected light, and it is on this latter
feature that the Invention is based. The positive proof thus developed,
there then only remains to immerse it in a bath containing from
10 to 15 per cent. of gelatine in solution, and to apply the paper upon
which the photo is to be mounted, and which is also passed through the
bath. The picture is now allowed to dry and the image is detached
from the glass, remaining as glossy as the glass itself. This glaze is not
produced by a layer of gelatine, but by the image itself which is
completely insoluble and will consequently bear considerable friction
whilo even water will not affect its appearance and durability.
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By means of the above described process I thus obtain an image
which is in fact unalterable, and which is itself preserved by an almost.
inattackable body, viz., (insoluble bi-chromated gelatine, i.c., the picture
itself), the image being obtained in the true position, that is to say, not
reversed, so that two poses will not be required to produce a pendant,
that is to say, two portraits of persons face to face. I may also obtain
the same result without transferring or detaching the picture and protect
the same by means of a material proof against the action of acids or heat,
viz., mica, which can be cleaned in the same manner as glass and also
withstand rubbing. The picture obtained in carbon is developed on this
permanent support (mica), it being then simply necessary to paste
thercon a sheet of white or colored paper of the tint desired, and to
attach the same by pasto or gelatine to the card mount. In this manner
the usual protecting glass of passe partouts are rendered unnecessary, the
mica itself affording the required protection while remaining as flexible
as the card itself.
If it is desired to have an ornamental groundwork or border of any
kind in imitation of marbling, leather, or otherwise, it is simply necessary
to copy the design and obtain from the negative a number of prints with a
salts of silver for subsequent use, care being taken to cover with a mask,
the space upon which the carbon picture is to be obtained. By thus
operating the desirod tint may be harmonized by toning with the tint of

page_text: the prepared paper, which is effected at one and the same operation after,
development.
The gradual strengthening which I apply to the salts of chromium®
consists of a solution of 300 grammes of water, one drop of liquid
ammonia, and 1 gramme of sugar, further adding according to the
desired intensity of the negative a few drops of saturated solution of'
permanganate of potassa. The negative is placed in a bath containing
this solution, and if desired to obtain still greater intensity some more
permanganate of potassa is added. The negativo thus strengthened will
produce proofs of the same quality as the primary one.
I also obtain proofs with salts of chromium on ordinary albumenized
paper with borders of different tints to that of the picture. For this.
purpose I take ordinary albumenized paper of any quality and expose it'
to the light after sensitising, I then place it in the press, taking care to
preserve a blank for the picture, with a black or yellow mask, and in this
manner I obtain an impression of the border from the negative. I then
precipitate it with hyposulphite and fix as in ordinary, obtaining in this
manner two tints, one for the picture and the other for the border. The
groundwork or border may however be printed on fine paper by the aid
of lithography of any tint or pattern desired, a blank being left for the
picture as before.
Further, in order to give a fleshy appearance to portraits I apply
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5 SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Scal Patent
Office on the 20th April 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lanc, in the County of Middlesex,
0 Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of October, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty-

page_text: eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Melville Clark, Her special
licence, that I, the said Alexander Melville Clark, my executors,
administrators, and assigns, or such others as I, the said Alexander
Melville Clark, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN PRODUCING CARBON PHOTOGRAPHS," a communication
to me from abroad by Claude Léon Lambert, of Paris, France,
upon the condition (amongst others) that I, the said Alexander
Melville Clark, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Scal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Alexander Melville Clark, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement, that is to say:-
This Invention relates to the production of carbon photographs (viz.,
with salts of chromium) which are permanent, involve less than half the
manipulation necessary for salts of silver pictures, and are produced
returned in their true aspect, and gelatinized at the same operation. To
this end I take a glass plate of suitable dimensions, upon which I first
apply a greasy coating, and then a layer of normal collodion, after which
I immerse it in cold water. I then remove from their printing frames the
pigmented papers and apply one on the coated glass plate whilst it is
still in the bath. I then remove both together, glass and paper, and
subject the same to slight pressure for a few minutes, after which I
immerse in warm water to develop the positive print, which according to
the length of exposure will serve either as a transparency, that is to say,
a picture seen by transmitted light, or one seen by reflected light; it is
upon this latter feature (the picture seen by reflected light) that the
Invention is based.. The positive print having been thus developed it is

page_text: only necessary to immerse it in a bath of gelatine solution (containing
from 10 to 15 per cent. of gelatine), and to apply the card mount which
is also passed through this bath. The picture is then allowed to dry
thoroughly, after which it is detached from the glass and remains as
brilliant and glossy as the surface with which it was in contact. This
brilliancy is not produced by the layer of gelatine, but by the image
itself which is completely insoluble, and will consequently bear
considerable friction and might even be wetted without its appearance or
durability being affected.
By the above process a permanent image is obtained which is itself
preserved by an almost unattackable substance (insoluble bi-chromated
gelatine, i.e., the picture itself), and which is obtained in its true aspect,
that is to say, non-reversed. Thus in practice it will not be necessary to
have two poses to produce a pendant, that is to say, two portraits of
persons face to face. The same result may also be obtained without
transfer or detachment, and the picture be at the same time protected by
means of a material not liable to be acted on by acids or heat, viz., mica,
which can be cleaned in the same manner as glass and will withstand
rubbing. The picture obtained in carbon is developed on this definitive
support (mica), it being simply necessary to paste at the back thereof a
sheet of white or colored paper of the tint desired, and then to attach it
with paste or gelatine to the card mount. In this manner the usual
protecting glass of passe partouts is rendered unnecessary, the mica
which is as flexible as the card itself affording the necessary protection.
If it is desired to have an ornamental ground or border of any kind in
imitation of marbling, leather, or otherwise, it is simply necessary to
copy these designs and obtain from the negative a number of prints in
salts of silver for subsequent use, care being taken to cover the place for
the carbon picture with an oval, square, or round cornered mask, which
part will thus remain white. By thus operating the tint which it is
desired to obtain may be harmonized by toning with the tint of the
pigmented paper, which is effected at one and the same operation after
development.
The gradual strengthening which I apply to the salts of chromium
consists of a solution of 300 grammes of water, one drop of liquid
ammonia, and 1 gramme of ordinary sugar of commerce, in addition to
which according to the desired intensity of the negative I add a few
drops of saturated solution of permanganate of potash. The negative

page_text: obtained from a positive by transmitted light is then placed in this bath,
and if it is desired to obtain still greater intensity some more of the
saturated solution of permanganate of potash is added. The negative
thus strengthened will produce prints which are exact repetitions of the
original. In this manner also the transparent positive may be intensified
in order to impart greater brilliancy to the negative to be obtained from
it. I therefore claim this means of intensifying "clichés" obtained in
salts of chromium.
I also claim obtaining prints in salts of chromium on ordinary
albumernized paper with borders in a scale of different tints which
contrast with that of the picture. For this purpose I take ordinary
albumenized paper of any quality and expose it to light after sensitizing,
then place it in the press, taking care to preserve a blank for the picture
with a black or yellow mask, and in this manner I obtain an impression
from a negative of any ornamental border with a blank space reserved
for the picture. I then precipitate with hyposulphite and fix as in
ordinary, and if desired apply it to the oval or square photograph. By
this means I obtain on the same sheet two tints which harmonize
perfectly, one for the picture and the other for the border. If however
it is not desired to have recourse to this photographic process, I may
lithograph on fine paper of varied or graduated tint, any desired
impression such as a plain or ornamental ground; an oval or round
cornered blank being left for the picture as before.
Further, in order to give a fleshy appearance to bust portraits I apply.
either by hand or by lithography before the application of the portrait a
graduated flesh tint over about two-thirds of the oval, whereby a most
harmonious effect is obtained.
:
The following relates to an infallible method of retouching and
intensifying the positive print obtained by the transferring processes
hercin-before described. By its aid any photographer without possessing
the least artistic skill, may in the space of a few minutes completely
transform the appearance of the picture. The image in salts of chromium
being obtained and developed as before described, after being alumed is
allowed to dry thoroughly. I then take a stump of suitable size,
according to the effect which it is desired to produce, and charge it with
powder composed of the tint required, and rub it over the surface, more
or less, whereby a wonderful optical effect is obtained. The insoluble

page_text: gelatine composing the image, after the repeated washings to which it
has been subjected presents a matt and imperceptibly granular surface,
and it is upon this dull surface composed of myriads of invisible grains,
that I apply broadly at the back of the picture the new powder to
impart opacity to those parts which require either modelling or darkening.
No fixing agent is required, as the gelatine upon the mask being applied
will serve to retain the powder and render perfectly invisible the retouch
which serves to harmonize the parts and improve the picture.