Improvements in Preparing Safety Paper for Cheques or other Documents.
Year: 1887

page_text: Date of Application, 18th May, 1887
Complete Left, 16th Feb., 1888
Complete Accepted, 16th Mar., 1888
Improvements in Preparing Safety Paper for Cheques or other
Documents.
We, ROBERT CHARLES MENZIES, of Inveresk Mills, Musselburgh, in the County of
Mid Lothian, North Britain, Paper Manufacturer, and CHARLES MILLARD KING of
4 New Court, Lincoln's Inn, London, in the County of Middlesex, Analytical Chemist,
do hereby declare the nature of this Invention to be as follows, that is to say :-
This Invention has for its object to prepare paper in an improved manner so as to
form a safety paper for cheques or other documents, the improved preparation being
such that writing on the paper cannot be obliterated by chemical means without
leaving stains.
Our Invention consist in incorporating with or applying to the paper compounds
which, on the application of an acid or alkaline solution (such as would be used for
obliterating writing) will cause the formation of ferrocyanides of copper and of
manganese, separately or jointly, and will cause the paper to be stained.
For this purpose we add to or intimately mix with the paper preferably whilst in
the state of pulp, compounds of copper and manganese easily decomposable by weak
acid solutions, such for example as the phosphates of those metals; together with a
ferrocyanide which is insoluble in water such for example as the ferrocyanide of zinc.
Or the manganese may be added to the paper in a soluble form, such as the sulphate,
by passing the web of paper through a solution of a soluble salt of manganeso.
Dated this Seventeenth day of May 1887
EDMUND HUNT,
Applicants' Agent.

page_text: We, ROBERT CHARLES MENZIES, of Inveresk Mills, Musselburgh, in the County of
Mid Lothian, North Britain, Paper Manufacturer, and CHARLES MILLARD KING of
4 New Court, Lincoln's Inn, London, in the County of Middlesex, Analytical Chemist,
do hereby declare the nature of this 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 say :-
This Invention has for its object to prepare paper in an improved manner so as to
form a safety paper for cheques or other documents, the improved preparation being
such that writing on the paper cannot be obliterated by chemical means without
leaving stains.
Our Invention consists in incorporating with or applying to the paper chemical
agents or compounds, which on the application of any acid or alkaline solution that
may be used in attempting to obliterate writing will cause the paper to be stained,
an acid causing the formation of ferrocyanide of copper, and an alkali causing the
formation of ferrocyanide of copper and oxide of manganese.
In carrying out our Invention we make the pulp in the beater so as to give a
neutral reaction with litmus which may be done by carefully adding solution of alum
after the size has been added in the usual way. The pulp being neutral we add to it
in the beater phosphate of copper, ferrocyanide of zinc, and phosphate of manganese,
one after the other, a short time being allowed to elapse between the additions of the
three salts. The porportions used may be varied in different cases, but the following
have been found to give good results, namely, 4 parts phosphate of copper, 2 parts
ferrocyanide of zinc, and 2 parts phosphate of manganese to the quantity of pulp
corresponding to one hundred parts by weight of dry pulp. The paper is then
finished in the ordinary way.
Instead of adding the phosphate of manganese to the pulp there may be applied to
the paper a solution containing about 2 parts of the sulphate or other soluble salt of
manganese to one hundred parts water, the web of paper being passed through the
solution.
For the phosphates of copper and of manganese any salts of those metals easily
decomposable by weak acid or alkaline solutions may be substituted, and for the
ferrocyanide of zinc there may be substituted any ferrocyanide which is insoluble in
water.
When the chemical agents or compounds are added to the pulp in an insoluble
form they must be in a state of fine division obtained by grinding or precipitation.

page_text: Having now particularly described and ascertained the nature of our said Invention
and in what manner the same is to be performed, we declare that what we
claim is :-
Safety paper for cheques and other documents prepared with phosphates or other
easily decomposable salts of copper and of manganese and with an insoluble ferro-
cyanide and thereby put in a condition to become stained on being moistened with an
acid or alkaline solution, such solution causing the formation in the paper of ferro-
cyanide of copper or of oxide of manganese or of both substantially as herein before
described.
TA
EDMUND HUNT,
Applicants' Agent.