IMPROVEMENTS IN PHOTOGRAPHY
Year: 1864

page_text: LETTERS PATENT to Joseph Wilson Swan, of Gateshead, in the County of
Durham, Chemist, for the Invention of "IMPROVEMENTS IN PHOTOGRAPHY."
Sealed the 14th June 1864, and dated the 29th February 1864.
PROVISIONAL SPECIFICATION left by the said Joseph Wilson Swan at
the Office of the Commissioners of Patents, with his Petition, on the
29th February 1864.
I, JOSEPH WILSON SWAN, of Gateshead, in the County of Durham, Chemist,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
PHOTOGRAPHY," to be as follows:-
My Invention relates to improved modes of producing photographic prints,
first, by means of a gelatinous photographic tissue, and second, by means of
prepared paper.
In carrying out the first part of my Invention, I prepare a tissue consisting
of a film of gelatinous matter united to a supporting film of collodion or other
suitable substance or combination of substances. The gelatinous film is
combined with carboniferous or other suitable colouring matter, and also with
such chemical substance or substances (for instance a salt or salts of
chromium) as when acted upon by light renders the gelatinous film insoluble
in water.
My mode of operation is as follows:-I apply to a surface of glass, metal, or
other suitable substance, a coating of collodion or other suitable film-producing

page_text: substance, or alternate coatings of collodion and other suitable film-producing
substance; and upon the film formed I apply a photographically sensitive
gelatinous solution containing coloring matter, which, when dry, forms in
conjunction with the collodion film a tissue separable from the surface on
which it was formed. Or I reverse the operation, and first produce the
gelatinous film and afterwards form the collodion or other supporting film in
the gelatinous film. As the tissue is sensitive to light, its preparation must
be carried on in a room suitably lighted for the purpose. The photographic
tissue formed as described is to be used in the manner of ordinary photo-
graphic paper, that is to say, it is to be placed behind the negative and
exposed to light which passes through the negative, the collodion or supporting
film being put in contact with the negative. After exposure to light, the
tissue is to be mounted, with the exposed face downward, either on a temporary
support during developing, with a view to future transfer to another basis, or
it is to be mounted upon the paper, card, glass, earthenware, or other surface on
which the picture is to remain. After mounting, the tissue is to be treated with
warm water so as to obtain the development of the photographic impression
by the solution and removal of those parts of the gelatinous film which have
not been acted upon by the light. In those cases where the tissue is mounted
before development on the surface to which it is to remain permanently
attached the process as described is complete after development; and where
the tissue was only temporarily mounted during the development of the print
with a view to subsequent transfer to a new surface the operation will be
complete after such transfer is effected.
The second part of my Invention relates to the preparation of paper intended
to be used in photographic printing. In preparing the paper I proceed as
follows I take paper or card and coat it with collodion or other suitable
substance so as to render it impervious to the gelatinous, albumenous, or
gummy solution to be afterwards applied to it, I then coat the paper in a
suitably lighted room with a gelatinous, albuminous, or gummy solution con-
taining carbon or other suitable coloring matter, and such chemical substance
or substances (for instance a salt or salts of chromium) as when acted upon
by light renders the colored film insoluble in water. The photographic paper
prepared in the manner described is to be used to print upon by means of
negatives as in ordinary photographic printing, the effect of light being made
apparent by treating the print with water after exposure.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Wilson Swan in the Great Seal Patent Office on
the 29th August 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
WILSON SWAN, of Gateshead, in the County of Durham, Chemist, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of February, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-seventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Joseph Wilson Swan, Her special license that I, the said
Joseph Wilson Swan, my executors, administrators, and assigns, or such
others as I, the said Joseph Wilson Swan, 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 PHOTOGRAPHY," upon the condition (amongst others) that I,
the said Joseph Wilson Swan, by an instrument in writing under my hand
and seal, 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 Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Joseph Wilson Swan, do hereby
declare the nature of my 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):-
My Invention relates to that manner or style of photographic printing
known as carbon or pigment printing. In this style of printing carbon or
other coloring matter is fixed by the action of light passing through a negative,
and impinging upon a surface composed of gelatine or other like substance
colored with carbon or other coloring matter, and made sensitive to light
by means of bichromate of potash or bichromate of ammonia or other
chemical substance having like photographic property. Those portions of th
colored and sensitive gelatinous surface which are protected from the lip. by
the opaque or semi-opaque portions of the negative being afterward washed
away by means of water, while the parts made insoluble by light emain and
form a print. This kind of photographic printing, although possessing the

page_text: advantage of permanency and affording the means of ensuring any required
tone or color for the print, has not come into general use because of the
difficulties hitherto experienced in obtaining by it delicacy of detail and
complete gradation of light and shade.
The difficulties referred to were more particularly experienced in attempts
to employ paper coated with the colored gelatinous materials, and arose from
the fact that in order to obtain half-tone certain portions of the colored coating
lying behind or at the back of the photographically impressed portions require
to be washed away, and the employment of paper in the way it has been
employed hitherto, not only as a means of supporting the colored coating,
but also to form ultimately the basis or groundwork of the print, obstructed
the removal of the inner or back portions of the colored coating and prevented
the obtaining of half-tone.
Now my Invention consists in the formation of tissues adapted to the
manner of printing referred to, and composed of or prepared with colored
gelatinous matter, and so constructed that while they allow in the act of
printing free access of light to one surface of the colored gelatinous matter,
they also allow free access of water, and the unobstructed removal of the non-
affected portions of the colored matter from the opposite surface or back in
the act of developing, and I obtain this result either by the disuse of paper
altogether, or by the use of it merely as a backing or temporary support of
the colored gelatinous matter, the paper so used becoming entirely detached
from the colored gelatinous matter in the act of developing, and forming no
part of the print ultimately.
My Invention consists, furthermore, in the special mode of using the said
tissues, whereby superior half-tone and definition in the print are obtained as
aforesaid, and also of a mode of transferring the print after developing from a
temporary to a permanent support, so as to obtain a correction in the position
of the print in respect of right and left. In producing the photographic
tissues referred to I form a solution of gelatine, and for the purpose of im-
parting pliancy to the resultant tissue I have found it advisable to add to the
gelatine solution, sugar, or other saccharine matter or glycerine. To the said
gelatinous solution I add carbonaceous or other coloring matter, either in a
fine state of division, such as is used in water colour painting, or in the state
of a solution or dye, or partly in a fine state of division and partly in solution.
With this colored gelatinous solution I form sheets or films as hereafter
described, and I render such sheets or films sensitive to light either at the time
of their formation by introducing into the gelatinous compound bichromate of
ammonia, or other photographic agent of like photographic properties, or by

page_text: applying to such non-sensitive sheets or films after their formation a solu-
tion of the bichromate or other substance of like photographic property. This
latter method I adopt when the sheet or film is not required for use imme-
diately after its formation. I will in my future references to the bichromate
of ammonia, or the bichromate of potash, or to other chemicals possessing
analogous photographic properties, denominate them "the sensitiser," and in
referring to the colored gelatinous solution I will denominate this mixture
"the tissue compound." When the tissue to be produced is required for im-
mediate use I add the sensitiser to the tissue compound, but where the tissue is
required to be preserved for some time before using I prefer to omit the sen-
sitiser from the tissue compound with a view to the tissue being made sensitive
to light subsequently by the application of a solution of the sensitiser. With
respect to the composition of the tissue compound it will be understood by
chemists that it may be varied without materially affecting the result by the
addition or substitution of other organic matters similarly acted upon by light,
when combined with a salt of chromium, such as I have referred to. Such
other organic matters are gum arabic, albumen, dextrine, and one or more of
these may be employed occasionally to modify the character of the tissue
compound, but I generally prefer to make it as follows:-I dissolve by the
aid of heat two parts of gelatine in eight parts of water, and to this solution
I add one part of sugar, and as much coloring matter in a finely divided
state, or in a state of solution, or both, as may be required for the production
of a photographic print with a proper gradation of light and shade. The
quantity required for this purpose must be regulated by the nature of the
coloring matter employed, and also by the character of the negative to be used
in the printing operation. Where it is desired that the coloring matter of the
print should consist entirely or chiefly of carbon I prefer to use lamp black
finely ground and prepared as for water color painting, or I use Indian ink;
and where it is desired to modify the black I add other coloring matter to
produce the color desired. For instance, I obtain a purple black by adding
to the carbon indigo and crimson lake, or I add to the carbon an aniline dye
of a suitable color. Where the coloring matter used is not a solution or dye,
but solid matter in a fine state of division, such as Indian ink or lampblack,
I diffuse such coloring matter through water or other inert liquid capable of
5 holding it in suspension, and after allowing the coarser particles to subside I
add of that portion which is held in suspension as much as is required to the
gelatine solution. In preparing tissue to be used in printing from negatives
technically known as "weak," I increase the proportion of coloring matter
relatively to that of the tissue compound, and I diminish it for tissue or paper

page_text: to be used in printing from negatives of an opposite character. Having pre-
pared the tissue compound, as before described, I proceed to use it as
follows: For preparing sensitive tissue I add to the tissue compound more
or less of the sensitiser, varying the quantity added according to the nature of
the sensitiser, and to the degree of sensitiveness to be conferred on the tissue
to be produced from it. For ordinary purposes, and where the tissue com-
pound is made according to the formula before given, I add about one part of
a saturated solution of bichromate of ammonia to ten parts of the tissue com-
pound, and I make this addition immediately previous to the preparation of
the tissue, and I maintain the tissue compound in the fluid state by means of
heat during the preparation of the tissue, avoiding the use of an unnecessary
degree of heat. I also filter it through fine muslin or flannel, or other
suitable filtering medium, previous to use, and I perform all the operations
with the tissue compound subsequent to the introduction of the sensitiser in
a place suitably illuminated with yellow or non-actinic light. In forming
tissue upon a surface of glass I first prepare the glass, so as to facilitate the
separation of the tissue from it. For this purpose I apply ox gall to the
surface of the glass (by means of a brush or by immersion,) and allow it to dry.
The glass is then ready for coating with the tissue compound. Or I apply to
the glass a coating of collodion previous to the application of the coating of
tissue compound. In this case the preparation with ox gall is unnecessary.
When collodion is used the collodion may consist of about ten grains of
pyroxyline in one ounce of a mixture of equal parts of sulphuric ether and
alcohol. I apply the collodion by pouring it on the surface to be coated and
draining off the excess, and I allow the coating of collodion to become dry
before applying the coating of tissue compound. I generally use a plain
surface on which to form the tissue, but surfaces of a cylindrical or other
form may sometimes be used advantageously. In preparing sheets of
sensitive tissue on a plane surface of glass I prefer to use the kind of glass
known as plate or patent plate. Before applying the sensitive tissue com-
pound I set the plate to be coated, so that its upper surface lies in a
horizontal position, and I heat the plate to about the same temperature as the
tissue compound, that is generally to about 100° Fahrenheit. The quantity
of the tissue compound that I apply to the glass varies with circumstances,
but is generally about two ounces to each square foot of surface coated.
After pouring the requisite quantity of the tissue compound upon the surface
of the plate, I spread or lead the fluid by means of a glass rod or soft brush
over the entire surface, taking care to avoid the formation of air bubbles, and
I keep the surface in the horizontal position until the solidification of the

page_text: tissue compound. In coating other than plane surfaces I vary in a suitable
manner the mode of applying the tissue compound to such surfaces. In
coating a cylindrical surface I rotate the cylinder in a trough containing the
tissue compound, and after having produced a uniform coating I remove the
trough, and keep up a slow and regular rotation of the cylinder until the
coating has solidified. After coating the surface of glass or other substance
as described, I place it in a suitable position for rapid drying, and I accelerate
this process by artificial means, such as causing a current of dry air to pass
over the surface coated; or I use heat in addition to the current of air; or I
place it in a chamber containing quicklime, chloride of calcium, or other
substance of analogous desiccating property. When the tissue is dry I sepa-
rate it from the surface on which it was formed by making an incision
through the coating to the glass around the margin of the sheet, or I cut
through the cylindrical coating near the ends of the cylinder, and also cut the
coating across parallel with the axis of the cylinder, when by lifting one
corner the whole will easily separate in a sheet. Where the tissue compound
is applied over a coating of collodion the film produced by the collodion and
that produced by the tissue compound cohere, and the two films form one
sheet. Sometimes before the separation of the coating from the glass I
attach to the coating a sheet of paper for the purpose of strengthening the
tissue and making it more easy to manipulate; I generally apply the paper in
a wet state to the dry gelatinous surface, and having attached the paper
thereto in this manner I allow it to dry, and I then detach the film and
adherent paper from the glass by cutting around the margin of the sheet and
lifting it off as before described. When extreme smoothness of surface, such as
is produced by moulding the tissue on glass as described, is not of importance,
and where greater facility of operation is desired, I apply a thick coating of the
tissue compound to the surface of a sheet of paper. In this case the paper is
merely used as a means of forming and supporting temporarily the film pro-
duced from the tissue compound, and such paper separates from the gelatinous
coating in a subsequent stage of my process. In coating a surface of paper
with the sensitive tissue compound I apply the sheet sometimes of con-
siderable length to the surface of the tissue compound contained in a trough,
and kept fluid by means of beat, and I draw or raise the sheet or length of
paper off the surface with a regular motion, and I sometimes apply more than
one coating to the same sheet in this manner. After such coating I place the
coated paper where it will quickly dry, and seclude it from injurious light.
The sensitive tissue, prepared as before described, is when dry ready to receive

page_text: the photographic impression by exposure under a negative in the usual
manner, or by exposure in a camera obscura to light transmitted through a
negative in the manner usual in printing by means of a camera. I prefer to
use the sensitive tissue within two days of the time of its preparation.
Where the tissue is not required for immediate use I omit the sensitiser from
the tissue compound, as before mentioned, and with this non-sensitive tissue
compound I coat paper, glass, or other surface as described in the preparation
of the sensitive tissue or paper. In preparing sheets of non-sensitive tissue
by means of glass, as described, I use no preliminary coating of collodion. I
dry the non-sensitive tissue in the same manner as the sensitive, except that
in the case of the non-sensitive tissue seclusion from daylight is not necessary.
The non-sensitive tissue is made sensitive when required for use by floating
the gelatinous surface upon a solution of the sensitiser, and the sensitiser that
I prefer to use for this purpose is an aqueous solution of the bichromate of
potash, containing about two and a half per cent. of this salt. I apply the
sensitiser by floating or otherwise to the gelatinous surface of the tissue, and
after this I place it in a suitable position for drying, and seclude it from
injurious light.
In applying to photographic printing the various modifications of the
sensitive tissue prepared as before described, I place the sensitive tissue upon
a negative in an ordinary photographic printing frame, and expose to light in
the manner usual in photographic printing. Or I place it in a camera
obscura in the manner usual in printing by means of a camera obscura. When
the tissue employed is coated with a film of collodion on one side, I place the
collodionized side in contact with the negative, or where it is used in the
camera I place the collodionised side towards the light passing through the
camera lens. Where the tissue is not coated with collodion, and where paper
forms one of the surfaces of the tissue, the other surface being formed of a
coating or film of the tissue compound, I place this last-named surface in
contact with the negative, or when using it in the camera I present this
surface towards the light transmitted by the lens. After exposure for the
requisite time, I take the tissue from the printing frame or camera, and mount
it in the manner herein-after described, (that is to say), I cement the tissue
with its exposed surface, or, in other words, with that surface which has
received the photographic impression, downward upon some surface (usually
of paper) to serve temporarily as a support during the subsequent operation
of developing, and with a view to the transfer of the print after development
to another surface; or I cement it (also with the exposed or photographically

page_text: be
impressed surface downward) upon the surface to which it is to remain per-
manently attached. The surface on which it is so mounted may paper,
card, glass, porcelain, enamel, &c. Where the tissue has not been coated with
collodion previous to exposure to light, I prefer to coat it with collodion on the
exposed or photographically impressed side before mounting it for develop-
ment; but this is not absolutely necessary, and I sometimes omit the coating
with collodion, more particularly where the print is intended to be colored
subsequently. Or where I employ collodion with a view to connect the
minute and isolated points of the print firmly together during development,
I sometimes ultimately remove the film it forms by means of a mixture of
ether and alcohol after the picture has been finally mounted and the support
of the film of collodion is no longer required. In mounting the exposed tissue
or paper (previous to development) in the temporary manner with a view to
subsequent transfer to another surface, I employ in the mounting a cement
that is insoluble in the water used in the developing operation, but that can
bo dissolved afterwards by the application of a suitable solvent, or one that
possesses so little tenacity that the paper or other support attached temporarily
to the tissue or paper by its means may be subsequently detached without the
use of a solvent.
The cements that may be used for temporary mounting are very various,
but I generally prefer to use a solution of india-rubber in benzole or other
solvent containing about six grains of india-rubber in each ounce of the solvent,
and I sometimes add to the india-rubber solution a small proportion of
dammar-gum or gutta percha. In using this cement I float the photo-
graphically impressed surface of the tissue upon it, and I treat in a similar
manner the paper or other surface intended to be used as the temporary mount
or support during development, and after allowing the benzole or other solvent
to evaporate, and while the surfaces coated with the cement are still tacky,
them strongly together in such a manner as to cause them to cohere.
When the photographically impressed, but still undeveloped tissue, is to be
cemented to a surface that not only serves to support the picture during its
development, but also constitutes permanently the basis of the picture, I prefer
to use albumen or starch paste as the cementing medium, and where I employ
albumen I coagulate or render it insoluble in water (by means of heat, by
alcohol, or by other means) after performing the cementing operation, and
previous to developing. In the permanent, as in the temporary mode of
mounting, I cement the tissue with its photographically impressed surface
downward upon the surface to which it is to be permanently attached.
I
press

page_text: After mounting the tissue as before described, and allowing the cement used
time to dry, where it is of such a nature as to require it, I then submit the
mounted tissue to the action of water sufficiently heated to cause the solution
and removal of those portions of the colored gelatinous matter of the tissue
which have not been rendered insoluble by the action of light during exposure
in the printing frame or camera. Where paper has been used as a part of
the original tissue, this paper soon becomes detached by the action of the
warm water, which then has free access to the under stratum or back of the
colored gelatinous coating, and the soluble portions of it are therefore readily
removed by the action of the water, and by this means the impression is
developed that was produced by the action of light during the exposure of the
tissue in the printing frame or camera, and the picture remains attached to
the mount cemented to the photographically impressed surface previous to
development. I allow the water to act upon the prints during several hours,
so as to dissolve out the decomposed bichromate as far as possible. I then
remove them from the water and allow them to dry, and those not intended
for transfer, but that have been permanently attached to paper previous to
development, I finish by pressing and trimming in the usual manner. Those
which have been temporarily mounted I transfer to paper, card, or other
surface. In transferring to paper or card, I coat the surface of the print with
gelatine, gum arabic, or other cement of similar character, and allow it to dry;
I then trim the print to the proper shape and size, and place its surface in
contact with the piece of paper or card to which the transfer is to be effected,
such piece of paper or card having been previously moistened with water, and
I press the print and mount strongly together; and after the paper or card
has become perfectly dry, I remove the paper or other supporting material
temporarily attached previous to development, either by simply tearing it off
where the cement used in the temporary mounting is of a nature to allow of
this without injury to the print, or I apply to the temporary mount benzole or
turpentine or other solvent of the cement employed; or I immerse the print
in such solvent, and then detach the temporary mount, and so expose the
reverse surface of the print, and after removing from the surface of the print
by means of a suitable solvent any remains of the cement used in the
temporary mounting, I finish the print by pressing in the usual manner. If,
however, the print be collodionized, and be required to be tinted with water
colors, I prefer to remove the collodion film from the surface of the print, and
this I do by the application of ether and alcohol.
Having now set forth the nature of my Invention of improvements in

page_text: photography, and explained the manner of carrying the same into effect, I
wish it to be understood that under the above in part recited Letters Patent
I claim,
First, the preparation and use of colored gelatinous tissues in the manner
and for the purpose above described.
Secondly, the mounting of undeveloped prints obtained by the use of
colored gelatinous tissues in the manner and for the purpose above described.
Thirdly, the remounting or transference of developed prints produced as
above described from a temporary to a permanent support.
In witness whereof, I, the said Joseph Wilson Swan, have hereunto
set my hand and seal, the Twenty-seventh day of August, in the year
of our Lord One thousand eight hundred and sixty-four.
JOSEPH WILSON SWAN. (L.S.)