IMPROVEMENTS IN THE MANUFACTURE, PRODUCTION, OR PREPARATION OF BANKERS' CHEQUES AND OTHER MONETARY INSTRUMENTS OR DOCUMENTS TO PREVENT FRAUDULENT ALTERATIONS THEREIN.
Year: 1881

page_text: LETTERS PATENT to August Dupré, of Westminster Hospital, Broad
Sanctuary, in the County of Middlesex, Professor of Chemistry, and Otto
Hehner, of 54, Holborn Viaduct, in the City of London, Analytical Chemist,
for an Invention of "IMPROVEMENTS IN THE MANUFACTURE, PRODUCTION, OR
PREPARATION OF BANKERS' CHEQUES AND OTHER MONETARY INSTRUMENTS
OR DOCUMENTS TO PREVENT FRAUDULENT ALTERATIONS THEREIN.'
"
PROVISIONAL SPECIFICATION left by the said August Dupré and Otto
Hehner at the Office of the Commissioners of Patents on the 27th January
1881.
"
AUGUST DUPRÉ, of Westminster Hospital, Broad Sanctuary, in the County of
Middlesex, Professor of Chemistry, and OTTO HEHNER, of 54, Holborn Viaduct, in
the City of London, Analytical Chemist. "IMPROVEMENTS IN THE MANUFACTURE,
PRODUCTION, OR PREPARATION OF BANKERS' CHEQUES AND OTHER MONETARY
INSTRUMENTS OR DOCUMENTS TO PREVENT FRAUDULENT ALTERATIONS THEREIN,'
This Invention has for its object improvements in the manufacture or production
of bankers' cheques and other monetary instruments or documents to prevent
fraudulent alterations therein, for which purpose in the manufacture or production
of such instruments we use a metallic sulphide or sulphides insoluble in water but
soluble in or acted upon by dilute or weak acid (preferring sulphide of zinc) in
admixture with a salt or salts of a heavy metal or metals (preferring carbonate of
lead or salts of bismuth) forming black or dark coloured sulphides not soluble either
in dilute acids or in alkaline sulphides. Such a mixture when brought into contact
with chemicals such as an acid, an alkali, or cyanide of an alkali, which may be
and are used to erase writing ink from paper, will immediately yield a sulphide
whose intense black or dark colour will render apparent the attempted alteration
of the cheque or other document.

page_text: In carrying out our Invention we prefer the use of ingredients that are white or
colourless, for instance, sulphide of zinc and carbonate of lead.
The mixture may be applied by incorporating it with the paper in process of
manufacture, or by incorporating it with the colouring paste now employed in the
printing of cheques, or by printing upon coloured cheques, such as the "Secure
Cheques" ordinarily supplied by Messrs. Charles Skipper and East, of London,
with a paste containing the protective mixture a pattern, or marks, or words either
identical with or different from those which form the visible printing upon the
cheque, or by printing upon the back of the document a pattern with a coloured
or colourless paste containing the mixture, or by a combination of two or more of
the above described methods.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said August Dupré and Otto Hehner in the Great Seal Patent Office on
the 23rd July 1881.
AUGUST DUPRÉ, of Westminster Hospital, Broad Sanctuary, in the County of
Middlesex, Professor of Chemistry, and Orro HEHNER, of 54, Holborn Viaduct, in
the City of London, Analytical Chemist. "IMPROVEMENTS IN THE MANUFACTURE,
PRODUCTION, OR PREPARATION OF BANKERS' CHEQUES AND OTHER MONETARY
INSTRUMENTS OR DOCUMENTS TO PREVENT FRAUDULENT ALTERATIONS THEREIN.'
This Invention has for its object improvements in the manufacture or production
of bankers' cheques and other monetary instruments or documents to prevent
fraudulent alterations therein.
"3
For this purpose in the manufacture or production of such instruments we use a
metallic sulphide or sulphides (insoluble in water but soluble in or acted upon by
dilute or weak acid) in admixture with a salt or salts of a heavy metal or metals,
which mixture will form (when acted upon by dilute or weak acid) black or dark
coloured sulphides not soluble either in dilute acids or in alkaline sulphides. Such
a mixture when brought into contact with chemicals such as an acid, an alkali, or
cyanide of an alkali, which may be (and frequently are) used to erase writing ink
from paper, will immediately yield a sulphide whose intense black or dark colour
will render apparent the attempted alteration of the cheque or other document.
In carrying out our Invention we prefer the use of ingredients that are white or
colourless, for instance, sulphide of zinc, and carbonate of lead, or salts of
bismuth.
The mixture may be applied by incorporating it with the paper in process of
manufacture, or by incorporating it with the colouring paste now employed in the
printing of cheques, or by printing upon ordinary coloured cheques (such for
instance as the "Secure Cheques ".ordinarily supplied by Messrs. Charles Skipper
and East, of London) with a paste containing the protective mixture above
described a pattern, or marks, or words either identical with or different from
those which form the visible printing upon the cheque, or by printing upon the
back of the document a pattern with a coloured or colourless paste containing the
mixture, or by a combination of two or more of the above described methods.
The method of preparing and applying the protective mixture we consider most
advantageous is as follows:-We mix thoroughly one part of pure precipitated
sulphide of zinc with two parts of carbonate of lead or its equivalent of the other
metallic salt previously mentioned. To this we add pure glycerine and treacle and
solution of gum-arabic in order to and we work the whole into a perfectly smooth
stiff paste of the consistency of ordinary printer's ink, or we may work the whole
into a perfectly smooth stiff paste of the consistency of ordinary printer's ink with
any liquid material free from alum or acid, alkali, or cyanide of an alkali, and
suitable for printing.
The white paste produced as just described is used for printing or otherwise
imparting an invisible pattern or words or marks over the face or back of the
cheque or other document. This may be effected by printing with our protective
mixture in the same manner as ordinary surface printing is done with ordinary
coloured paste.
Or the Invention may be carried out by adding to the ordinary coloured paste
used in cheque printing a suitable amount of the mixture of sulphide of zinc
and carbonate of lead (or its equivalent of the other metallic salt previously
mentioned in the proportions of 1:2, and conducting the printing operation in the
ordinary manner. The greater the proportion of protective mixture in the paste
the better will be the result. An addition of 25 per cent. of protective mixture
.

page_text: yields a very sensitive paste. This paste must be free from alum, acid, alkali, or
cyanide of an alkali.
If the protective mixture is to be incorporated with the paper itself it is mixed
with the paper pulp (which must be free from alum, acid, alkali, and cyanide of an
alkali, and from excess of hyposulphite) either in the pulp beating, machines or
after the pulp is properly beaten in the vats or boxes which feed the paper
machine. The paper pulp thus becomes equally mixed with the protective mixture.
The size used in sizing the paper must be free from falum, acid, alkali, or cyanide
of an alkali. The proportion of metallic mixture added to the paper pulp is a
matter of little importance, but paper containing 10 per cent. of the same fully
answers the intended purpose.
Having described the nature of the said Invention, and the manner of carrying
it into practical effect, we would have it understood that what we consider to be
new and claim as secured to us under the hereinbefore in part recited Letters
Patent is,-
In the manufacture, production, or preparation of bankers' cheques and other
monetary instruments or documents, the use of sulphide of zinc or other metallic
sulphide or sulphides insoluble in water but soluble in or acted upon by dilute
or weak acid in admixture with carbonate of lead or other salt or salts of a heavy
metal or metals in such manner that if weak acid, or alkali, or cyanide of an alkali,
be applied to alter such a cheque or other document, the said mixture being acted
upon by such weak acid, alkali, or cyanide of an alkali, will form in or on the
said cheque or other document a dark stain or stains, substantially as above
described for the purposes set forth.
•
In witness whereof, we, the said August Dupré and Otto Hehner, have hereunto
set our hands and seals, this Twenty second day of July, in the year of our
Lord One thousand eight hundred and eighty one.