IMPROVEMENTS INC OBTAINING! 5 PICTURES; OR REPRESENTATIONS OF OBJECTS
Year: 1841

page_text: C..
*
Photographic Pictures.
12
Is . "
TALBOTS SPECIFICATION AND DISCLAIMER.
J TO ALL TO WHOM THESE PRÉSENTS SHALL COME, Ï, WILLIAM
HENRY FOX TALBOT, of Lacock Abbey, in the County of Wilts, Esquire, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria; by Her
5 Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster; the Eighth day of February, in the fourth year of Her reign, did, for
Herself; Her heirs, and successors, give and grant-unto me, the said William
Henry Fox Talbot, Her especial licence, full power, sole privilege and authority,
that I, the said William Henry Fox Talbot, my exors, admiors, and assigns, or
0 such others as I, the said William Henry Fox Talbot; my exors, admiors; or
assigns, should at any time agree with; and no others, from time to time and
at all-times during the term of years therein expressed should' and' lawfully
might make, use, exercise, and vend, within England, Wales, and the; Town'
of Berwick-upon-Tweed; my Invention of "IMPROVEMENTS INC OBTAINING!
5 PICTURES; OR REPRESENTATIONS OF OBJECTS;" in which said Letters Patent' is
contained a proviso, that F, the said William Henry-Fox Talbot, shall causo al
particular description of the nature of my said Invention; and' in what manner
the same is to be performed; to be inrolled in Her said Majesty's High Court
of Chancery, within six' calendar months.next and immediately after the date
0 of the said in part recited Letters Patent, as in and by the same, reference
being thereunto-had, will inore fully and at large appear.
NOW KNOW YE; that in compliance with the said proviso; I, the said.
William Henry Fox Talbot, do' hereby declare the nature of my said'Invention,

page_text: and the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof (that is to say) :-
The first part of my Invention is a method of making paper extremely
sensitive to the rays of light. For this purpose I select the best writing paper,
having a smooth surface and a close and even texture.
First Part of the Preparation the Paper. I dissolve one hundred grains
of crystallised nitrate of silver in six ounces of distilled water, I wash one side
of the paper with this solution with a soft camel hair brush, and place a mark
upon that side by which to know it again. I dry the paper cautiously at a
distant fire, or else I leave it to dry spontaneously in a dark place. Next, I
dip the paper in a solution of iodide of potassium, containing five hundred
grains of that salt dissolved in one pint of water, I leave the paper a minute
or two in this solution, I then take it out and dip it in water, I then dry it
lightly with blotting paper and finish drying it at a fire; or else I leave it to
dry spontaneously; all this process is best done in the evening by candle light.
The paper thus far prepared may be called, for the sake of distinction, "iodized
paper." This iodized paper is scarcely sensitive to light, but, nevertheless, it
should be kept in a portfolio or some dark place till wanted for use; it does
not spoil by keeping any length of time provided it is kept in a portfolio, and
not exposed to the light.
4
Second Part of the Preparation of the Paper.-This second part is best
deferred until the paper is wanted for use; when that time is arrived, I tako
a sheet of the iodized paper, and wash it with a liquid prepared in the following
manner: Dissolve one hundred grains of crystallised nitrate of silver in two
ounces of distilled water, to this solution add one-sixth of its volume of strong
acetic acid; let this mixture be called A. Dissolve crystallized gallic acid in
distilled water as much as it will dissolve (which is a very small quantity); let
this solution be called B. When you wish to prepare a sheet of paper for use,
mix together the liquids A and B in equal volumes. This mixture I shall call
by the name of gallo-nitrate of silver. Let no more be mixed than is intended
to be used at one time, because the mixture will not keep good for a long
period. Then take a sheet of iodized paper and wash it over with this gallo-
nitrate of silver with a soft camel hair brush, taking care to wash it on the
the side which has been previously marked. This operation should be per-
formed by candle light. Let the paper rest half a minute, and then dip it
into water, then dry it lightly with blotting paper, and lastly, dry it cautiously
at a fire, holding it a considerable distance therefrom. When dry the paper is
fit for use, but it is advisable to use it within a few hours after its preparation.
(Note, that if it is used immediately the last drying may be dispensed with,,
.

page_text: and the paper may be use moist). (Note 2nd, instead of using a solution of
gallic acid for the liquid B, the tincture of galls diluted with water may be
used, but it is not so advisable.
Use of the Paper.-The paper thus prepared, and which I name "calotype
paper," is placed in a camera obscura, so as to receive the image formed in
the focus of the lens, of course the paper must be screened or defended from
the light during the time it is being put into the camera. When the camera
is properly pointed at the object, this screen is withdrawn, or a pair of internal
folding doors are opened, so as to expose the paper for the reception of the
image. If the object is very bright, or the time employed is sufficiently long,
a. sensible image is perceived upon the paper when it is withdrawn from the
camera. But when the time is short, or the objects dim, no image whatever
is visible upon the paper, which appears entirely blank. Nevertheless, it is
impressed with an invisible image; and I have discovered the means of causing
this image to become visible. This is performed as follows:-I take some
gallo-nitrate of silver, prepared in the manner before directed, and with this
liquid I wash the paper all over with a soft camel hair brush, I then hold it
before a gentle fire, and in short time (varying from a few seconds to a minuto
or two), the image begins to appear upon the paper. Those parts of the
paper upon which light has acted the most strongly become brown or black,
while those parts on which light has not acted remain white. The image
continues to strengthen and grow more and more visible during some time.
When it appears strong enough, the operation should be terminated and the
picture fixed.
The Fixing Process.-In order to fix the picture thus obtained, I first dip it
into water, I then partly dry it with blotting paper, and then wash it with a
solution of bromide of potassium, containing one hundred grains of that salt
dissolved in eight or ten ounces of water. The picture is then washed with
water, and then finally dried. Instead of bromide of potassium, a strong
solution of common salt may be used, but it is less advisable. The picture
thus obtained will have its lights and shades reversed with respect to the
natural objects; videlicet, the lights of the objects are represented by shades,
and vice versa. But it is easy from this picture to obtain another, which shall
be conformable to nature; videlicet, in which the lights shall be represented by
lights, and the shades by shades: It is only necessary for this purpose to take a.
second sheet of sensitive calotype-paper, and place it in close contact with the
first, upon which the picture has been formed.. A board is put beneath them,
and a sheet of glass above, and the whole is pressed into close contact by
screws. Being then placed in sunshine, or daylight, for a short time, an image

page_text: or copy is formed upon the second sheet of paper. This image or copy-is-
often invisible at first, but the image may be made to appear in the same way
that has been already stated. But, I do not recommend that the should
copy
be taken on calotype paper, on the contrary, I would advise that it should be
taken on common photographic paper. This paper is made by: washing, good
writing paper first with a weak solution of common salt, and next with a
solution of nitrate of silver, since it is well known, having been freely com-
municated to the public by myself, in the year One thousand eight hundred
and thirty-nine, and that it forms no part of the present Invention, I need not
describe it here more particularly; although it takes a much longer time to
obtain a copy upon this paper than upon calotype paper,. yet the tints of the
copy are generally more harmonious and agreeable. On whatever paper the
copy is taken, it should be. fixed in the way already described. After a
calotype picture has furnished a good many copies, it sometimes grows faint;
and the subsequent copics are inferior. This may be prevented by means of a
process which revives the strength of the calotype pictures. In order to this,
it is only necessary to wash them by candle light with gallo-nitrate of silver;
and then warm them. This causes. all the shades of the picture to darken
considerably, while the white parts are unaffected. After this the picture is,
of course, to be fixed a second time. The picture will then yield a second
series of copies, and a great number of them may frequently be made.
(Note. In the same way in which I have just explained that a faded
calotype picture may be revived and restored, it is possible to strengthen and
revive photographs which have been made on other descriptious of sensitive
potographic paper; but these are inferior in beauty, and, moreover, the result
is less to be depended upon; I therefore do not recommend them.
The next part of my Invention consists in a mode of obtaining positive
photographic pictures, that is to say, photographs in which the lights of
the object are represented by lights, and the shades by shades. I have already
described how this may be done by a double process; but I shall now describe
the means of doing it by a single process. I take a sheet of sensitive calotype
paper, and expose it to daylight until I perceive a slight but visible dis-
coloration or browning of its surface. This generally occurs in a few seconds
I then dip the paper into a solution of iodide of potassium, of the same
strength as before, videlicet, five hundred grains to one pint of water: This
immersion apparently removes the visible impression caused by the ligh
(nevertheless, it does not really remove it, for if the paper were to be now
washed with gallo-nitrate of silver it would speedily blacken all over). The
paper when taken out of the iodide of potassium is dipped in water, and thon

page_text: lightly dried with blotting paper, it is then placed in the focus of a camera
obscura which is pointed at an object; after five or ten minutes the paper is
withdrawn and washed with gallo-nitrate of silver, and warmed as before
directed; an image will then appear of a positive kind, namely, representing
the lights of the object by lights, and the shades by shades. Engravings may
be very well copied in the same way, and positive copies of them obtained at
once (reversed, however, from right to left). For this purpose a sheet of
calotype paper is taken and held in daylight to darken it as before mentioned,
but for the present purpose it should be more darkened than if it were
intended to be used in the. camera obscura. The rest of the process is the
same. The engraving and the sensitive paper should be pressed into close
contact with screws, or otherwise, and placed in the sunshine, which generally
effects the copy in a minute or two; this copy, if it is not sufficiently distinct;
must be rendered visible, or strengthened with the gallo-nitrate of silver, as
before described.
I am aware that the use of iodide of potassium for obtaining positive photo-
graphs has been recommended by others, and I do not claim it here by itself as a
new Invention, but only when used in conjunction with the gallo-nitrate of silver;
or when the pictures obtained aro rendered visible or strengthened subsequently
to their first formation: In order to take portraits from the life, I prefer to use
for the object glass of the camera a lens whose focal length is only three or
four times greater than the diameter of the aperture. The person whose
portrait is to be taken should be so placed that the head may be as steady as
possible, and the camera being then pointed at it, an image is received on the
sensitive calotype paper. I prefer to conduct the process in the open air;
under a serene sky, but without sunshine; the image is generally obtained in
half a minute or a minute. If sunshine is employed, a sheet of blue glass
should be used as a screen to defend the eyes from too much glare, because
this glass does not materially weaken the power of the chemical rays to affect
the paper. The portrait thus obtained on the calotype paper is a negative
one, and from this a positive copy may be obtained in the way already
described.
I claim, first, the employing gallic acid or tincture of galls, in conjunction
with a solution of silver, to render paper which has received a previous pre-
paration more sensitive to the action of light.
Secondly, the making visible photographic images upon paper, and the
strengthening such images when already faintly or imperfectly visible by
washing them with liquids which act upon those parts of the paper which
have been previously acted upon by light.

page_text: Thirdly, the obtaining portraits from the life by photographic means upon
paper.
Fourthly, the employing bromide of potassium, or some other soluble
bromide, for fixing the images obtained.
The next part of my Invention is a method of obtaining photogenic images
upon copper. For this purpose I take a plate of polished copper, and expose
it to the vapour of iodine or bromine, or of these two substances united, or of
either of them, in union with chlorine; or else I dip the plate of copper into
a solution of some of the above-mentioned substances in alcohol, ether, or
otlier convenient solvent. By this means the copper surface becomes sensitive
to light; a photogenic image is then to be formed upon it in the usual manner.
The plate is then to be exposed to the vapour of sulphuretted hydrogen, or of
one of the liquid hydro-sulphurets. This vapour produces various colors upon
the surface of the copper, but it acts differently or produces a different color
on those parts of the surface which have been exposed to light, and on those
which have not been so exposed, consequently a colored photogenic image is
obtained, and as this image is not destroyed by a subsequent exposure to light;
no further fixing process is requisite. Instead of the vapour of sulphuretted
hydrogen, other vapours or liquid solutions which color the surface of copper
(as, for instance, iodine, bromine, and chlorine) may be employed, but with
less advantage.
With respect to this branch of my Invention, I claim the above-mentioned
methods of rendering a surface of copper sensitive to light, and the method of
rendering the photogenic image colored and permanent by subsequent exposure
to vapours or liquids, which act differently on those parts of the surface that
have been exposed and those not exposed to light.
The next part of my Invention is as follows:-A smooth surface of steel,
platina, or other suitable metal, is coated with an extremely thin layer of silver;
the silver is then made sensitive to light by the methods now well known, and
a photogenic image is received upon it; the plate, with the image, is then
placed in a horizontal position, and a solution of acetate of lead in water
is poured upon it; a galvanic current is then made to pass through the
plate and the solution, which causes a colored film to precipitate upon the
plate.
With respect to this branch of my Invention, I claim tho application of the
eolored films produced by a solution of lead when acted on by galvanism to
the purpose of obtaining photogenic images, which are colored or otherwise
diversified.
The next part of my Invention is a method of obtaining very thin silver

page_text: plates or surfaces, for the purpose of economy in the processes of photography
in which such are used, and also for the greater convenience of transport in
travelling. For this purpose, I precipitate on a polished metal plate a thin
layer of copper, by the galvanic process now well known by the name of
electrotype; I then cement or glue a sheet of paper or card to the back of
this layer of copper, and when it is dry I remove the paper with the layer
of copper adhering; this copper is then silvered by dipping it into any suitable
solution of silver.
The last part of my Invention consists in transferring photogenic images
from paper to metal. In order to this the metallic surface is made sensitive
to light; the paper photograph is then placed on.it with a sheet of glass in
front, and the whole is pressed into firm contact by screws, or otherwise, and
exposed to sunshine. A photograph on metal is thus obtained, which is after-
wards to be fixed, and to be otherwise treated according to the effect intended
to be obtained.
I have already described the means of transferring the image on one descrip-
tion of sensitive paper to another description of sensitive paper; and with
respect to this branch of my Invention, I claim the transferring photogenic'
pictures obtained upon sensitive paper to a metallic surface, or to a different.
kind or quality of sensitive paper; I do not confine myself to the precise*
weights and measure of the substances employed in these processes which I-
have mentioned, since they may be varied according te circumstances; but I:
have mentioned those which I have found on the whole to be the most
convenient.
In witness whereof, I, the said William Henry Fox Talbot, have here-
unto set my hand and seal, this Twenty-ninth day of July, One thousand
cight hundred and forty-one.
WILLIAM HENRY (L.S.) FOX TALBOT.
AND BE IT REMEMBERED, that on the Twenty-ninth day of July, in
the year of our Lord 1841, the aforesaid William Henry Fox Talbot came
before our said Lady the Queen in Her Chancery, and acknowledged the
Specification aforesaid, and all and every thing therein contained and specified,
in form above written. And also the Specification aforesaid was stamped
according to the tenor of the Statute made for that purpose.
Inrolled the Seventh day of August, in the year of our Lord One thousand
eight hundred and forty-one.

page_text: En the Matter of a Patent granted to William Henry Fox Talbot, of
Lacock Abbey, in the County of Wilts, Esquire,, for his Invention
of "IMPROVEMENTS IN OBTAINING PICTURES, OR REPRESENTATIONS OF
OBJECTS," bearing date at Westminster, the Eighth February, One
thousand eight hundred and forty-one, to which a Specification was
duly enrolled.
DISCLAIMER proposed to be filed by the said William Henry Fox Talbot,
pursuant to the provisions of the Statutes in that behalf, that is to
'say:
I, the said William Henry Fox Talbot, do hereby disclaim the following
part of the said Specification, that is to say, the part thereof commencing with.
the words, "The next part of my Invention is a method of obtaining photo-
genic images upon copper," and extending from those words and including the
same continuously to the end of the said Specification. My reasons for such
Disclaimer are, that the parts of my said Invention so disclaimed being of a
separate character, and independant of the first and principal parts of my said
Invention, as described in the said Specification, and more of a scientific than.
a practical nature. I am advised that in any action brought for an imfringe-
ment of the said Patent objections may be raised, which would require evidence
to be adduced in support respectively of those parts of my said Invention
which I disclaim, thereby adding to the expense and difficulty of such action;
and therefore, although I still fully believe that I am the first and truo
Inventor of the said parts of the said Invention, yet I consider it advisable to
disclaim them, as aforesaid.
In witness whereof, I, the said William Henry Fox Talbot, have here-
unto set my hand and seal, this Sixth day of March, in the year of
our Lord One thousand eight hundred and fifty-four
W. H. F. TALBOT. (L.S.)
To the Clerk of the Patents of England.
This is to certify, That William Henry Fox Talbot, of Lacock Abbey, in the
County of Wilts, Esquire, has applied to me for leave to file with you tho
above written Disclaimer of a certain Invention for which Letters Patent were

page_text: duly granted to him under the Great Seal of the United Kingdom, dated the
8th day of February 1841, a Specification to which was duly enrolled; and
having considered the said application, and no caveat having been entered
against the same, I have accordingly granted leave to the said William Henry
Fox Talbot to file his said Disclaimer, pursuant to the Statute in such case.
made and provided.
And I hereby also certify that any action may be brought in respect of any
infringement committed prior to the filing of this Disclaimer, notwithstanding
the entry or filing of the same, and pursuant to the Statute in that case made.
and provided.
AND BE IT REMEMBERED, that on the Sixth day of March, in the year
of our Lord 1854, the aforesaid William Henry Fox Talbot came before our
said Lady the Queen in Her Chancery, and acknowledged the Disclaimer
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Disclaimer aforesaid was stamped according to
the tenor of the Statute made for that purpose.

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HENRY FOX TALBOT, of Lacock Abbey; in the County of Wilts, Esquire, send
greeting..
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
Ininster, the Eighth day of February, in the fourth year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto me, the said William
Henry Fox Talbot, Her especial licence, full power, sole privilege and authority,
that I,, the said William Henry Fox Talbot, my exors, adññors, and assigns, or
such others as I, the said William Henry Fox Talbot, my exors, adiñors, or
assigns, should at any time agree with, and no others, from time to time and
at all times during the term of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town
of Berwick-upon-Tweed, my Invention of "IMPROVEMENTS IN OBTAINING
PICTURES, OR REPRESENTATIONS OF OBJECTS;" in which said Letters Patent is
contained a proviso, that I, the said William Henry Fox Talbot, shall cause a
particular description of the nature of my said Invention, and in what manner
the same is to be performed, to be inrolled in Her said Majesty's High Court
of Chancery, within six calendar months next and immediately after the date
of the said in part recited Letters Patent, as in and by the same, reference
being thereunto bar, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Henry Fox Talbot, do hereby declare the nature of my said Invention,

page_text: and the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof (that is to say):-
The first part of my Invention is a method of making paper extremely
sensitive to the rays of light. For this purpose I select the best writing paper,
having a smooth surface and a close and even texture..
First Part of the Preparation of the Paper.-I dissolve one hundred grains
of crystallised nitrate of silver in six ounces of distilled water, I wash one side
of the paper with this solution with a soft camel hair brush, and place a mark
upon that sido by which to know it again. I dry the paper cautiously at a
distant fire, or else I leave it to dry spontaneously in a dark place. Next, I
dip the paper in a solution of iodide of potassium, containing five hundred
grains of that salt dissolved in one pint of water, I leave the paper a minute
or two in this solution, I then take it out and dip it in water, I then dry it
lightly with blotting paper and finish drying it at a fire; or else I leave it to
dry spontaneously; all this process is best done in the evening by candle light.
The paper thus far prepared may be called, for the sake of distinction, " iodized
paper." This iodized paper is scarcely sensitive to light, but, nevertheless, it
should be kept in a portfolio or some dark place till wanted for use; it does
not spoil by keeping any length of time provided it is kept in a portfolio, and
not exposed to the light.
Second Part of the Preparation of the Paper.-This second part is best
deferred until the paper is wanted for use; when that time is arrived, I take
a sheet of the iodized paper, and wash it with a liquid prepared in the following
manner-Dissolve one hundred grains of crystallised uitrate of silver in two
ounces of distilled water, to this solution add one-sixth of its volume of strong
acetic acid; let this mixture be called A. Dissolve crystallized gallic acid in
distilled water as much as it will dissolve (which is a very small quantity); let
this solution be called B. When you wish to prepare a sheet of paper for use,
mix together the liquids A and B in equal volumes. This mixture I shall call
by the name of gallo-nitrate of silver. Let no more be mixed than is intended
to be used at one time, because the mixture will not keep good for a long
period. Then take a sheet of iodized paper and wash it over with this gallo-
nitrate of silver with a soft camel hair brush, taking care to wash it on the
the side which has been previously marked. This operation should be per-
formed by candle light. Let the paper rest half a minute, and then dip it
into water, then dry it lightly with blotting paper, and lastly, dry it cautiously
at a fire, holding it a considerable distance therefrom. When dry the paper is
fit for use, but it is advisable to use it within a few hours after its preparation.
(Note, that if it is used immediately the last drying may be dispensed with,

page_text: and the paper may be use moist). (Note 2nd, instead of using a solution of
gallic acid for the liquid B, the tincture of galls diluted with water may be
used, but it is not so advisable.
Use of the Paper. The paper thus prepared, and which I name "calotypo
paper," is placed in a camera obscura, so as to receive the image formed in
the focus of the lens, of course the paper must be screened or defended from
the light during the time it is being put into the camera. When the camera
is properly pointed at the object, this screen is withdrawn, or a pair of internal
folding doors are opened, so as to expose the paper for the reception of the
image. If the object is very bright, or the time employed is sufficiently long,
a sensible image is perceived upon the paper when it is withdrawn from the
camera. But when the time is short, or the objects dim, no image whatever
is visible upon the paper, which appears entirely blank. Nevertheless, it is
impressed with an invisible image; and I have discovered the means of causing
this image to become visible. This is perforined as follows:-I take some.
gallo-nitrate of silver; prepared in the manner before directed, and with this
liquid I wash the paper all over with a soft camel hair brush, I then hold it
before a gentle fire, and in short time (varying from a few seconds to a minute
or two), the image begins to appear upon the paper. Those parts of the
paper upon which light has acted the most strongly become brown or black,
while those parts on which light has not acted remain white. The imago
continues to strengthen and grow more and more visible during some time.
When it appears strong enough, the operation should be terminated and the
picture fixed.
.
The Fixing Process.-In order to fix the picture thus obtained, I-first dip it
into water, I then partly dry it with blotting paper, and then wash it with a
solution of bromide of potassium, containing one hundred grains of that salt
dissolved in eight or ten ounces of water. The picture is then washed with
water, and then finally dried. Instead of bromide of potassium, a strong
solution of common salt may be used, but it is less advisable. The picture
thus obtained will have its lights and shades reversed with respect to the
natural objects; videlicet, the lights of the objects are represented by shades,
and vice versa. But it is easy from this picture to obtain another, which shall
be conformable to nature; videlicet, in which the lights shall be represented by
lights, and the shades by shades. It is only necessary for this purpose to take a
second sheet of sensitive calotype paper, and place it in close contact with the
first, upon which the picture has been formed. A board is put beneath them,
and a sheet of glass above, and the whole is pressed into close contact by
screws. Being then placed in sunshine, or daylight, for a short time, an image

page_text: or copy is formed upon the second sheet of paper. This image or copy is
often invisible at first, but the image may be made to appear in the same way
that has been already stated.. But, I do not recommend that the copy should
be taken on calotype paper, on the contrary, I would advise that it should be
taken on common photographic paper. This paper is made by washing good
writing paper first with a weak solution of common salt, and next with a
solution of nitrate of silver, since it is well known, having been freely com-
municated to the public by myself, in the year One thousand eight hundred
and thirty-nine, and that it forms no part of the present Invention, I need not
describe it here more particularly; although it takes a much longer time to
obtain a copy upon this paper than upon calotype paper, yet the tints of the
copy are generally more harmonious and agreeable. On whatever paper the
copy is taken, it should be fixed in the way already described. After a
calotype picture has furnished a good many copies, it sometimes grows faint,
and the subsequent copies are inferior. This may be prevented by means of a
process which revives the strength of the calotype pictures. In order to this,
it is only necessary to wash them by candle light with gallo-nitrate of silver,
and then warm them. This causes all the shades of the picture to darken
considerably, while the white parts are unaffected. After this the picture is,
of course, to be fixed a second time. The picture will then yield a second
series of copies, and a great number of them may frequently be made.
(Note. In the same way in which I have just explained that a faded
calotype picture may be revived and restored, it is possible to strengthen and
revive photographs which have been made on other descriptious of sensitive
potographic paper; but these are inferior in beauty, and, moreover, the result
is less to be depended upon; I therefore do not recommend them.
The next part of my Invention consists in a mode of obtaining positive
photographic pictures, that is to say, photographs in which the lights of
the object are represented by lights, and the shades by shades. I have already
described how this may be done by a double process; but I shall now describe
the means of doing it by a single process. I take a sheet of sensitive calotype
paper, and expose it to daylight until I perceive a slight but visible dis-
coloration or browning of its surface. This generally occurs in a few seconds.
I then dip the paper into a solution of iodide of potassium, of the same
strength as before, videlicet, five hundred grains to one pint of water. This
immersion apparently removes the visible impression caused by the light
(nevertheless, it does not really remove it, for if the paper were to be now.
washed with gallo-nitrate of silver it would speedily blacken all over). The
paper when taken out of the iodide of potassium is dipped in water, and then

page_text: lightly dried with blotting paper, it is then placed in the focus of a camera
obscura which is pointed at an object; after five or ten minutes the paper is
withdrawn and washed with gallo-nitrate of silver, and warmed as before
directed; an image will then appear of a positive kind, namely, representing
the lights of the object by lights, and the shades by shades. Engravings may
be very well copied in the same way, and positive copies of them obtained at
once (reversed, however, from right to left). For this purpose a sheet of
calotype paper is taken and held in daylight to darken it as before mentioned,
but for the present purpose it should be more darkened than if it were
intended to be used in the camera obscura. The rest of the process is the
same. The engraving and the sensitive paper should be pressed into closo
contact with screws, or otherwise, and placed in the sunshine, which generally
effects the copy in a minute or two; this copy, if it is not sufficiently distinct,
must be rendered visible, or strengthened with the gallo-nitrate of silver, as
before described.
I am aware that the use of iodide of potassium for obtaining positive photo-
graphs has been recommended by others, and I do not claim it here by itself as a
new Invention, but only when used in conjunction with the gallo-nitrate of silver,
or when the pictures obtained are rendered visible or strengthened subsequently
to their first formation. In order to take portraits from the life, I prefer to use
for the object glass of the camera a lens whose focal length is only three or
four times greater than the diameter of the aperture. The person whose
portrait is to be taken should be so placed that the head may be as steady as
possible, and the camera being then pointed at it, an image is received on the
sensitive calotype paper. I prefer to conduct the process in the open air,
under a serene sky, but without sunshine; the image is generally obtained in
half a minute or a minute. If sunshine is employed, a sheet of blue glass
should be used as a screen to defend the eyes from too much glare, because
this glass does not materially weaken the power of the chemical rays to affect
the paper.
The portrait thus obtained on the calotype paper is a negative
one, and from this a positive copy may be obtained in the way already
described.
I claim, first, the employing gallic acid or tincture of galls, in conjunction
with a solution of silver, to render paper which has received a previous pre-
paration more sensitive to the action of light.
Secondly, the making visible photographic images upon paper, and the
strengthening such images when already faintly or imperfectly visible by
washing them with liquids which act upon those parts of the paper which
have been previously acted upon by light.

page_text: Thirdly, the obtaining portraits from the life by photographic means upon
paper.
Fourthly, the employing bromide of potassium, or some other soluble
bromide, for fixing the images obtained.
The next part of my Invention is a method of obtaining photogenic images
upon copper. For this purpose I take a plate of polished copper, and expose
it to the vapour of iodine or bromine, or of these two substances united, or of
either of them, in union with chlorine; or else I dip the plate of copper into
a solution of some of the above-mentioned substances in alcohol, ether, or
other convenient solvent. By this means the copper surface becomes sensitive
to light; a photogenic image is then to be formed upon it in the usual manner.
The plate is then to be exposed to the vapour of sulphuretted hydrogen, or of
one of the liquid hydro-sulphurets. This vapour produces various colors upon
the surface of the copper, but it acts differently or produces a different color
on those parts of the surface which have been exposed to light, and on those
which have not been so exposed, consequently a colored photogenic image is
obtained, and as this image is not destroyed by a subsequent exposure to light,
no further fixing process is requisite. Instead of the vapour of sulphuretted
hydrogen, other vapours or liquid solutions which color the surface of copper
(as, for instance, iodine, bromine, and chlorine) may be employed, but with
less advantage.
With respect to this branch of my Invention, I claim the above-mentioned
methods of rendering a surface of copper sensitive to light, and the method of
rendering the photogenic image colored and permanent by subsequent exposure
to vapours or liquids, which act differently on those parts of the surface that
have been exposed and those not exposed to light.
The next part of my Invention is as follows:-A sinooth surface of steel,
platina, or other suitable metal, is coated with an extremely thin layer of silver;
the silver is then made sensitive to light by the methods now well known, and
a photogenic image is received upon it; the plate, with the image, is then
placed in a horizontal position, and a solution of acetate of lead in water
is poured upon it; a galvanic current is then made to pass through tho
plate and the solution, which causes a colored film to precipitate upon the
plate.
With respect to this branch of my Invention, I claim the application of the
colored films produced by a solution of lead when acted on by galvanism to
purpose of obtaining photogenic images, which are colored or otherwise
diversified.
the
The next part of my Invention is a method of obtaining very thin silver

page_text: plates or surfaces, for the purpose of economy in the processes of photography
in which such are used, and also for the greater convenience of transport in
travelling. For this purpose, I precipitate on a polished metal plate a thin
layer of copper, by the galvanic process now well known by the name of
electrotype; I then cement or glue a sheet of paper or card to the back of
this layer of copper, and when it is dry I remove the paper with the layer
of copper adhering; this copper is then silvered by dipping it into any suitable
solution of silver.
The last part of my Invention consists in transferring photogenic images
from paper to metal. In order to this the metallic surface is made sensitivo
to light; the paper photograph is then placed on it with a sheet of glass in
front, and the whole is pressed into firm contact by screws, or otherwise, and
exposed to sunshine. A photograph on metal is thus obtained, which is after-
wards to be fixed, and to be otherwise treated according to the effect intended
to be obtained.
I have already described the means of transferring the image on one descrip-
tion of sensitive paper to another description of sensitive paper; and with
respect to this branch of my Invention, I claim the transferring photogenic
pictures obtained upon sensitive paper to a metallic surface, or to a different
kind or quality of sensitive paper; I do not confine myself to the precise
weights and measure of the substances employed in these processes which I
have mentioned, since they may be varied according te circumstances; but I
have mentioned those which I have found on the whole to be the most
convenient.
In witness whereof, I, the said William Henry Fox Talbot, have here-
unto set my hand and seal, this Twenty-ninth day of July, One thousand
icht hundred and forty-one !.
WILLIAM HENRY (L.s.) FOX TALBOT.
AND BE IT REMEMBERED, that on the Twenty-ninth day of July, in
the year of our Lord 1841, the aforesaid William Henry Fox Talbot came
before our said Lady the Queen in Her Chancery, and acknowledged the
Specification aforesaid, and all and every thing therein contained and specified,
in form above written. And also the Specification aforesaid was stamped
according to the tenor of the Statute made for that purpose.
Inrolled the Seventh day of August, in the year of our Lord One thousand
eight hundred and forty-one.

page_text: DISCLAIMER proposed to be filed by the said William Henry Fox Talbot,
pursuant to the provisions of the Statutes in that behalf, that is to
say:-
I, the said William Henry Fox Talbot, do hereby disclaim the following
part of the said Specification, that is to say, the part thereof commencing with
the words, "The next part of my Invention is a method of obtaining photo-
genic images upon copper," and extending from those words and including the
same continuously to the end of the said Specification. My reasons for such
Disclaimer are, that the parts of my said Invention so disclaimed being of a
separate character, and independant of the first aud principal parts of my said
Invention, as described in the said Specification, and more of a scientific than
a practical nature. I am advised that in any action brought for an imfringe-
ment of the said Patent objections may be raised, which would require evidence
to be adduced in support respectively of those parts of my said Invention
which I disclaim, thereby adding to the expense and difficulty of such action;
and therefore, although I still fully believe that I am the first and true
Inventor of the said parts of the said Invention, yet I consider it advisable to
disclaim them, as.aforesaid.
In witness whereof, I, the said William Henry Fox Talbot, have here-
unto set my hand and seal, this Sixth day of March, in the year of
our Lord One thousand eight hundred and fifty-four

page_text: duly granted to him under the Great Seal of the United Kingdom, dated the
Sth day of February 1841, a Specification to which was duly enrolled; and
having considered the said application, and no caveat having been entered
against the same, I have accordingly granted leave to the said William Henry
Fox Talbot to file his said Disclaimer, pursuant to the Statute in such case
made and provided.
And I hereby also certify that any action may be brought in respect of any
infringement committed prior to the filing of this Disclaimer, notwithstanding
the entry or filing of the same, and pursuant to the Statute in that case made
and provided.
5 AND BE IT REMEMBERED, that on the Sixth day of March, in the year
of our Lord 1854, the aforesaid William Henry Fox Talbot came before our
said Lady the Queen in Her Chancery, and acknowledged the Disclaimer
aforesaid, and all and every thing therein contained and specified, in form,
above written. And also the Disclaimer aforesaid was stamped according to
o the tenor of the Statute made for that purpose.