IMPROVE- MENTS IN PREPARING AND OBTAINING PHOTOGENIC PICTURES OR REPEE- SENTATIONS
Year: 1863

page_text: LETTERS PATENT to William Clark, of 58, Chancery Lane, in the County
of Middlesex, Engineer and Patent Agent, for the Invention of "IMPROVE-
MENTS IN PREPARING AND OBTAINING PHOTOGENIC PICTURES OR REPEE-
SENTATIONS."-A communication from abroad by Adolphe Teissonnière,
of 29, Boulevart St. Martin, Paris, Merchant.
Sealed the 14th July 1863, and dated the 21st January 1863.
PROVISIONAL SPECIFICATION left by the said William Clark at the
Office of the Commissioners of Patents, with his Petition, on the 21st.
January 1863.
I, WILLIAM CLARK, of 58, Chancery Lane, in the County of Middlesex,.
Engineer and Patent Agent, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN PREPARING AND OBTAINING PHOTOGENIC PICTURES OR
REPRESENTATIONS," to be as follows:-
This Invention relates to obtaining in common black ink a positive impression
directly from a positive.
1st, I take a sheet of paper albumenized with chloride of sodium or
hydrochlorate of ammonia, such as is generally used in photography, and
having cut the paper to the desired size, I place it on a smooth surface, the
presence of the above salts in the paper will tend at a later period to form
peroxide of iron.
2ndly, I take a concentrated solution of an ammoniacal salt, by preference

page_text: bichromate of potash or bichromate of ammonia, with which I slightly damp
a fine sponge, and then apply a coat to the albumenized face of the paper
with as much regularity as possible and without leaving any streaks. This
operation should be effected by candlelight.
3rdly, I take the object to be reproduced and place it in direct contact!
with the sensative sheet, and fix the whole in a frame used for that purpose,
which is then exposed in the sun for a time varying according to the intensity
of its rays.
4thly, the image being obtained I plunge it in water, when the soluble
parts will dissolve and leave the paper bare in its original condition. I then
place the proof on a smooth surface, and by the aid of a brush spread all over
the surface of the paper a solution of crystallized tannic acid or nut gall, and
after allowing three or four minutes for absorption I plunge the proof in a
weak bath of water in order to prevent the image from being injured by a
strong solution of sulphate of iron which is to be added to the bath by small
quantities and the mixture agitated.
5thly, the positive image will appear instantaneously, and I allow it to
remain in the bath for some minutes, afterwards withdrawing and washing it
in pure water in order to remove any precipitate of the peroxide with which
it may be stained; I then develop it in a fresh bath of iron where the outlines
become very distinct.
6thly, I take an alkalined bath weakened with water (at about 20 degrees
Beaumé) in which I plunge the proof, the organic matter protecting the
whites then dissolves and allows the paper to regain its original whiteness.
Under the action of the alkali the blacks become of a brown tint, they a
.however regain all their vigour by placing them in a weak bath of sulphate of
iron.
7thly, the proof when perfectly dry is protected from the oxygen by varnish-
ing or gumming, or by the application of any suitable caustic, it may be after-
wards pasted on a Bristol board. "Photogenic chemistry or the principle on
which rests the phenomenon of obtaining with black ink (tannate or gallate
of iron) a positive image direct from a positive."
It is well known that light acts chemically on certain bodies and com-
municates new properties thereto. The greater number of ammoniacal salts
(especially bichromate of potash) or bichromate of ammonia, under the action
of a luminous fluid solidify and become insoluble when previously combined
with an organic matter. Thus if a positive image be exposed to the light in
direct contact with an albumenized sheet of paper, on which is a layer of an
ammoniacal solution, the following is the result-1st, the ammoniacal solution

page_text: combines with the organic matter, and forms a solution which is sensitive to
the luminous fluid. 2ndly, the luminous rays traversing the diaphanous
parts of the image act on the sensitive substance and solidify and render it
insoluble. The black parts on the contrary intercept the rays and leave
soluble the parts unacted on, which, on being afterwards washed, give up the
substance and leave the paper exposed in its primitive condition. A negative
reproduction of the image is thus obtained. This process is generally known,
with this exception, that in the composition of the sensitive substance by the
ordinary process a given quantity of ammoniacal salt is intimately mixed .in
certain proportions with the organic matter, while, according to this Invention
it is simply necessary to apply the solution directly on the sheet of paper
previously albumenized with chloride of sodium or hydrochlorate of ammonia;
the presence of these salts in the paper acts at a later period as a mordant
on the formation of peroxide of iron only. The impressionable or white parts
being insoluble allow of the black parts absorbing a solution of tannin or
crystallized tannic or gallic acid, which in a bath of sulphate of iron forms a
new salt, tannate or gallate of iron, viz., the base of common black ink. The
impressionable protecting parts of the whites are dissolved by means of an
alkali weakened in water which abandons the paper and allows it to return to
its original whiteness. A positive proof is thus obtained in ordinary black ink
which may be protected from oxygen by any suitable varnish or by a caustic
composed of virgin wax and essence of turpentine dissolved in a warm
bath.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Clark in the Great Seal Patent Office on the 17th
July 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CLARK, of 53, Chancery Lane, London, in the County of Middlesex, Engineer
and Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of January, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-sixth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said William Clark, Her special licence, that I, the said William Clark,
my executors, administrators, and assigns, or such others as I, the said William
Clark, my executors, administrators, and assigns, should at any time agree

page_text: 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
PREPARING AND OBTAINING PHOTOGENIC PICTURES OR REPRESENTATIONS," a com"
to me from abroad by Adolphe Teissonnière, of 29, Boulevart St. Martin,
Paris, Merchant, upon the condition (amongst others) that I, the said
William 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 Seal Patent Office within six calendar months next and im-
mediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said William 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 a photogenic process whereby a positive image
may be obtained direct from a positive by the employment of ammoniacal
salts combined with the organic matter, and also by the precipitation of
the following metallic solutions, viz., salts of silver, copper, iron, nickel,
mercury, gold, palladium, platina, lead, or tellurium, which are precipitated by
means of hydrosulphates of ammonia, potash, or soda. The salts of silver,
bismuth, or lead, are precipitated by means of bydrosulphuric acid, and the
salts of mercury by hydrochlorate of tin. The salts of bismuth may also be
precipitated by means of nut galls, gallic or tannic acids, and the salts of
iron, by means of the same agents last mentioned. I take for example the
sulphate of iron precipitated by means of tannic acid.
OPERATIONS.

page_text: then exposed to the sun for a time varying according to the intensity of the
rays and the thickness of the proof.
4thly, the image being obtained I plunge it in water for about an hour,
when the soluble parts will dissolve, while the parts corresponding to the
whites of the image remain insoluble, being solidified by the action of the.
light, the parts which are left bare thus become absorbent.
5thly, I place the proof on a flat surface, and by the aid of a brush spread.
over the entire surface of the image a few drops of a solution of tannic acid,
nut gall, gallic acid, or other of the substances herein-before enumerated, which
are capable of being precipitated in black by means of agents also above.
stated.
6thly, immediately this is effected I run a quantity of water over the proof
in order to remove the excess of the above solution, and then plunge it in a
bath of water saturated with sulphate of iron. The image then appears
instantaneously by the formation of tannate or sulphate of iron. When this
has acquired a certain distinctness I wash the proof with pure water in order
to deprive it of the sulphate of iron, it is then left to dry and afterwards coated
with white varnish dissolved in alcohol. Photogenic chemistry or principle on-
which is based the phenomenon of obtaining with black ink (tannate or
gallate of iron) a positive image direct from a positive.
It is well known that light acts chemically on certain bodies and com-
municates new properties thereto. The greater number of ammoniacal
salts (especially bichromate of potash or bichromate of ammonia) under the
action of a luminous fluid solidify and become insoluble when previously
combined with an organic matter. Thus if a positive image be exposed to the
light in direct contact with an albumenized sheet of paper, on which is a layer
of an ammoniacal solution, the following is the result:-1st, the ammoniacal
solution combines with the organic matters, and forms a solution which is
sensitive to the luminous fluid. 2ndly, the luminous rays traversing the
diaphanous parts of the image act on the sensitive substance and solidify and
render it insoluble. The black parts on the contrary intercept the rays and
leave soluble the parts unacted on, which on being afterwards washed, give
up the substance and leave the paper exposed in its primitive condition.
A negative reproduction of the image is thus obtained.
This process is
generally known, with this exception, that in the composition of the sensitive
substance by the ordinary process a given quantity of ammoniacal salt is
intimately mixed in certain proportions with the organic matter, while
according to this Invention it is simply necessary to apply the solution directly
on the sheet of paper previously albumenized with chloride of sodium or

page_text: hydrochlorate of ammonia; the presence of these salts on the paper acts at a
later period as a mordant in the formation of peroxide of iron. The impres-
sionable or white parts being insoluble only allow of the black parts absorbing
a solution of tannin or crystallized tannic or gallic acid, which in a bath of
sulphate of iron forms a new salt, tannate of gallate of iron, viz., the base of
common black ink.. The impressionable protecting parts of the whites are
dissolved by means of an alkali weakened in water, which abandons the
paper, and allows it to return to its original whiteness. A positive proof is thus
obtained in ordinary black ink, which may be protected from oxygen by any
suitable varnish, or by a caustic composed of virgin wax and essence of
turpentine dissolved in a warm bath.
Having described the nature of, this Invention, and the manner of per-
forming the same, I declare that what I claim as the Invention to be
protected by the herein-before in part recited Letters Patent is, the application
of the above described photogenic process for obtaining a positive image
direct from a positive by the use of ammoniacal salts combined with the
organic matter, and by the precipitation of the metallic solutions, all as herein
described,
In witness whereof, I, the said William Clark, have hereunto set
my hand and seal, this Seventeenth day of July, in the year of our
Lord, One thousand eight hundred and sixty-three.
Witness,
W. G. E. SWINNOCK,
53, Chancery Lane,
London.
W. CLARK,
(L.B.)