AN IMPROVEMENT IN THE MANUFACTURE AND TREATMENT OF PAPER, WITH THE VIEW TO THE PREVENTION OF FORGERY
Year: 1858

page_text: LETTERS PATENT to William Herapath, of the City of Bristol, Analytical
Chemist, for the Invention of "AN IMPROVEMENT IN THE MANUFACTURE
AND TREATMENT OF PAPER, WITH THE VIEW TO THE PREVENTION OF FORGERY."
Sealed the 18th January 1859, and dated the 19th July 1858.
PROVISIONAL SPECIFICATION left by the said William Herapath at the
Office of the Commissioners of Patents, with his Petition, on the
19th July 1858.
I, WILLIAM HERAPATH, of the City of Bristol, Analytical Chemist, do hereby
declare the nature of the said Invention for "AN IMPROVEMENT IN THE
MANUFACTURE AND TREATMENT OF PAPER, WITH THE VIEW TO THE PREVENTION OF
FORGERY," to be as follows:-
I imbue paper, either during its manufacture or afterwards, with a solution
of some ferrocyanide, ferridcyanide, or sulphocyanide, either with or without a
colouring tint, so that upon applying any of the known agents for removing
writing ink a discolouration of the paper and a change of colour of the writing
ink shall occur without the ink being removed, and thus the attempt at
removal will be palpable. I prefer for this purpose the ferrocyanide, ferrid-
cyanide and sulphocyanide of potassium.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Herapath in the Great Seal Patent Office on the
19th January 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HERAPATH, of the City of Bristol, Analytical Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Nineteenth day of July, in the year of our Lord One
thousand eight hundred and fifty-eight, in the twenty-second year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said William Herapath, Her special licence that I, the said William
Herapath, my exccutors, administrators, and assigns, or such others as I, the
said William Herapath my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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 "AN IMPROVEMENT IN
THE MANUFACTURE AND TREATMENT OF PAPER, WITH THE VIEW TO THE PREVENTION
OF FORGERY," upon the condition (amongst others) that I, the said William
Herapath, 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 immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said William Herapath, 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 thereof, that is to say :-
My Invention consists in imbuing paper during the process of manufacture,
or in steeping it after it has been sized and pressed with a solution of a ferro-
cyanide, a ferrideyanide, or a sulphocyanide of potassium, sodium, or ammo-
nium; these salts, with the alum or alum cake used with size, produce a tint
which may be varied by the addition of small quantities of such metallic salts
as will produce the required tint. The color of common ink written upon
paper prepared with an excess of the ferrocyanide, ferrideyanide, or sulpho-
cyanide will, upon being exposed to the action of acids and elements of an
electro-negative character, be changed conspicuously from black to blue, or
red, according to the salt used, and with alkalies or electro-positives the ink

page_text: will be changed to a brown red, and will be partly obliterated, while the tint
and texture of the paper will render the attempt to extract the ink perfectly
visible. Experiments lead me to believe that it will be almost impossible to
commit forgery by extraction of the ink from paper so treated. I prefer the use
of the ferrocyanide and ferridcyanide of potassium for the purpose of my
Invention, as being cheap and readily obtained in commerce.
The pro-
portions to be used will vary according as alum or alum cake is used in
the size, and also according to the thickness of the paper and the solidity of
the size.
And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I claim impregnating
paper with the ferrocyanides, ferridcyanides, and sulphocyanides of potassium,
sodium, or ammonium in solution, in order that any attempt to remove
common ink from it shall be rendered evident.
In witness whereof, I, the said William Herapath, have hereunto set my
hand and seal, this Seventeenth day of January, One thousand eight
hundred and fifty-nine.
WILLIAM HERAPATH. (L.S.)