A NEW METHOD OF PRE- PARING WRITING PAPER FROM WHICH WRITING INK CANNOT BE EXPUNGED OR ABSTRACTED WITHOUT DETECTION
Year: 1837

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DAVID
STEVENSON, of Bath Place; New Road, in the County of Middlesex, Gentleman,
send greeting.
WHEREAS I did, by petition, humbly represent unto His late most
Excellent Majesty King William the Fourth, that "A NEW METHOD OF PRE-
PARING WRITING PAPER FROM WHICH WRITING INK CANNOT BE EXPUNGED OR
ABSTRACTED WITHOUT DETECTION," had been partly communicated to me by a'
Foreigner residing abroad and partly found out by myself, and His said'
Majesty, being willing to give encouragement to all arts and inventions' which'
may be for the public good, was graciously pleased, by His Royal Letters
Patent, and under the Great Seal of the United Kingdom of Great Britain'
and Ireland, bearing date at Westminster, the Second day of March last,
(One thousand eight hundred and thirty-seven) in the seventh year of His
reign, for Himself,. His heirs and successors, to give and grant unto me, the
said David Stevenson; my exors, admors, and assigns, His especial licence;
full power, sole privilege and authority, that I or they, by myself' or them-
selves, or by my or their deputies, servants or agents, or such others as
I or they should agree with (and no others), during the term of fourteen'
years from the date of the said Letters Patent, should and lawfully' might
make, use, exercise, and vend my said Invention within that part of His Ma-
jesty's United Kingdom of Great Britain and Ireland called. England, His
Dominion of Wales, and the Town of Berwick-upon-Tweed, and also in all His
Colonies and Plantations abroad, in such manner as to me, my exors, admors,
and assigns, shall seem meet, and as that I or they shall enjoy the whole.

page_text: profit and advantage arising by reason of the said Invention during the said
term of fourteen years; and for that end His said Majesty requires and strictly
commands all His subjects whatsoever within England, Wales, and the Town
of Berwick, and in the Colonies and Plantations abroad, that they shall not,
neither directly nor indirectly make, use, or put in practice my said Invention,
or any part thereof, nor in anywise counterfeit, imitate, or resemble the same,
nor make any addition thereto or subtraction therefrom, whereby to pretend
himself or themselves to be the Inventor or Inventors thereof. And whereas the
said Letters Patent contain a proviso obliging me, the said David Stevenson,
particularly to describe and ascertain the nature of the said Invention, and in
what manner the same is to be performed, by an instrument in writing,
under my hand and seal, and cause the same to be inrolled in His Majesty's
High Court of Chancery within six calendar months next and immediately
after the date of the said Letters Patent, as in and by the same, (reference
being thereunto had), will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
David Stevenson, do hereby declare that the said Invention is described and
ascertained in manner following, that is to say:-
The new method of preparing writing paper consists in incorporating a che-
mical preparation of suitable ingredients into the substance of the writing
paper so as not to cause any material difference between the appearance
thereof and that of ordinary writing paper; or in case any tint of colour
should be given to the paper by the said preparation, so as that it shall be a
uniform even tint, without clouds or variation of colour; in either case the said
chemical preparation, which is incorporated into the substance of the writing
paper, being in such state of existence therein as to cause the paper to assume
a decided and obvious change of appearance at any part of its surface to which
any chemical agents capable of expunging or abstracting writing ink from
writing paper may have been applied, such change of appearance. being a
visible stain, which will be evidence of the application of some such chemical
agents having been made. Wherefore writing paper prepared according to
the new Invention being used as ordinary writing paper would be for writing
letters, agreements, bills of exchange, receipts, promissory notes, wills, accounts,
or any other instruments in writing, or for account books, the writing thereon
being made with ordinary writing ink, (or any other kind of ink which may be
preferred for writing), then if any attempt is afterwards made to expunge or
abstract any words or portion of the writing from such paper by application
thereto of any chemical agents which are known to be capable of expunging or
abstracting writing ink from paper, the said paper so prepared according to the

page_text: new method will become visibly stained at every part of its surface to which
such chemical agents may have been so applied, and such stains will be produced
(but more or less obviously, and visibly) whether the writing ink has been effec-
tually expunged or abstracted by the said application, or only partially and im-
perfectly, or not at all, expunged or abstracted; and by such visible stains the
attempt which has been made to expunge or abstract, or the expunging or
abstraction which has been made, will be certainly detected, because the
chemical preparation which is incorporated into the paper, as aforesaid, will not
endure the action of such chemical agents as have the power to expunge or
abstract writing ink without undergoing an obvious change of colour on one or
both sides of the paper. And the chemical preparation which I have used with
success for preparing writing paper, and giving to it the property aforesaid, is
a solution of manganese 'prepared with a solution of prussiate of potass in
a liquid form, and mixed with the pulp whereof the writing paper is to
be made, so as that the metallic preparation cannot fail to become incorporated
with or equally diffused throughout the substance of the writing paper. I take
any convenient quantity of the manganese of commerce, such as is commonly
used by bleachers or paper makers for making their bleaching gas (say fifty
pounds weight), and put the same into the usual leaden vessel or retort, which
is commonly used for the aforesaid purpose, together with about four times as
much as the weight of manganese, or about two hundred pounds weight of the
muriatic acid of commerce, keeping the mixture continually stirred in the
retort, and applying gentle heat to the retort by surrounding it with hot water
or steam, according to the usual. and well-known treatment of manganese for
obtaining bleaching gas from it, and which gas will be evolved from the afore-
said mixture, and may be made use of in any manner that is desirable or
advantageous; but the gas is of no use for my purpose, and might be wasted
in the open air without any detriment thereto; but when the mixture ceases
to give out more gas I then draw off the residum remaining in the retort into
a vessel of wood, or other suitable material not subject to corrision from the
said residum, which being left to settle therein, I draw off the clear liquor for
use, leaving the deposit which has subsided as being useless for my purpose;
and to the said clear liquor I add fine powdered chalk or whiting dissolved in
water to the consistency of cream, pouring in small quantities thereof from
time to time, and stirring the mixture until no further effervescence will take
place. After this the mixture is to be heated until it just begins to shew
signs of boiling, and then being left to cool and settle, I draw off the clear
liquor for use, leaving the deposit which has subsided as being useless for my
purpose. The said liquor contains manganese in solution, and about, three

page_text: quarts thereof will be nearly a sufficient quantity to impregnate as much pulp
of rags as is usually contained in a paper maker's beating engine, and which is
commonly reckoned as one hundred weight of rags. I also dissolve one pound
of. prussiate of potass in five or six quarts of water, which may be previously
made warm to assist the solution, and then I mix the aforesaid solution of
manganese, with the solution of prussiate of potass; the mixture so obtained
forms a suitable metallic preparation for introducing into the substance of
writing paper to give it the property herein-before explained. But note, in
order to determine the relative quantities of the solutions of manganese and
of prussiate of potass which should be mixed together as aforesaid, I first
pour into the said quantity of five or six quarts of water, which contains one
pound of prussiate of potass in solution, only a part of the said three quarts of
solution of manganese, perhaps two quarts thereof, and then taking a small
sample of the mixture or milky-coloured liquor which is so produced, and
by filtering the same through blotting paper, a small quantity of transparent
liquid is obtained, into which I pour a few drops of the solution of manganese,
and if the same renders the transparent liquor milky again, that is a sign that
a further portion of the three quarts of solution of manganese should be added
to the mixture, which, being done, another sample is taken and filtered, and a
few drops of solution of manganese being put therein, if the filtered sample is
rendered milky thereby it shews that still more manganese may be added to
the mixture, but if the filtered sample is not rendered milky at the aforesaid
trial, or at another succeeding like trial which may be made for the purpose,
then it shews that the proper quantity of manganese has been introduced in
proportion to the quantity of prussiate of potass, in order to give the mixture
of the two solutions the intended quality; and the quantity of the said solution
of manganese, which is determined by the result of repeated trials, as aforesaid,
may be more or less than the three quarts herein-before mentioned, that being
only an approximation towards the proper quantity, which depends upon the
strength of the solution; but whatever quantity of the solution of manganese is
determined by the result of a series of the said trials to be proportionable for
one pound of prussiate of potass dissolved in five or six quarts or other conve-
nient quantity of water, the liquid mixture so obtained will be about a proper
quantity of metallic preparation to put ino an engine full of pulp for making
paper. And it will be best to pour the said liquid mixture or metallic prepa-
ration into the pulp whilst the same still remains in the beating engine, and
when it has arrived nearly at the last stage of its preparation, thereby so as
that the conclusion of the usual operation of the beating engine which remains
to be performed may produce a perfect mixture or incorporation of the metallic

page_text: preparation with the pulp. But note, in case the sizing for the writing paper
is to be applied to the pulp whilst it is in the engine, it will be better to pour
in and mix or incorporate the said metallic solution with the pulp, as aforesaid,
previously to mixing the size with the pulp, because the size might, if applied
first, have a tendency to impede the perfect mixture and incorporation of the
metallic preparation with the pulp, hence it will be better to introduce the
sizing after that incorporation has been effected. And the pulp having the
metallic preparation perfectly incorporated with it in manner aforesaid, is then
to be made into writing paper, according to the usual routine of paper-making
business, and the writing paper, when finished, will have been prepared
according to the new method, and will possess the quality herein-before
explained of becoming visibly stained by application of such chemical agents
as have sufficient, power to be used for expunging or abstracting writing ink
from paper.
::
Having now described the said new Method of Preparing Writing Paper from
which Writing Ink cannot be expunged or abstracted without Detection, I, the
said David Stevensou, do hereby declare that the said new Invention, whereof
the exclusive use is granted by the said Letters Patent, consists in preparing
writing paper by incorporationg into its substance a chemical preparation con-
taining some metallic or other base of a white or a pale colour, accompanied
by some chemical compound which will remain in the paper in a passive or
neutralized state, without exerting any chemical action on its accompanying
metallic or other base to produce colour or change of colour thereof; but,
nevertheless, when other chemical agents, capable of acting on writing ink, are
applied to paper having the said chemical preparation so incorporated into its
substance, as aforesaid, such chemical agents, by bringing the said passive or
neutralized compound into chemical activity upon its accompanying metallic or
other base, will produce visible colour, or change of colour, at those parts of the
paper to which the said chemical agents have been applied.. Wherefore, by
such method of preparing writing paper it will become visibly stained by appli-
cation of such chemical agents as have power to expunge or abstract writing
ink from paper; and in consequence of such stains being left after such appli-
cation, writing ink cannot be expunged or abstracted from writing paper
so prepared without detection. And although I have herein-before directed
manganese to be used as a metallic base, and prussiate of potass to be used as
a chemical compound, suitable for accompanying that base in the said
chemical preparation, which is to be incorporated into the writing paper for
the purpose aforesaid, nevertheless the Invention is not confined to the use of
those ingredients, but extends to such others as may be capable of giving to