AN IMPROVED MANUFACTURE OF SAFETY PAPER FOR CHEQUES AND SIMILAR PURPOSES
Year: 1885

page_text: UHIDIONAL
SPECIFICATION.
I, CHARLES DENTON ABEL, of No 28 Southampton Buildings, Chancery Lane
in the county of Middlesex, Consulting Engineer and Patent Agent do hereby
declare the nature of my invention for "AN IMPROVED MANUFACTURE OF SAFETY
PAPER FOR CHEQUES AND SIMILAR PURPOSES "
to be as follows:-
This invention relates to the manufacture of paper that shall at once indicate
any alteration effected by chemical means of writing or other marks made thereon.
The known methods for the production of such safety paper either do not offer
perfect security for the purpose required, on account of the chemical reagents
employed therein, or they are of such a complicated nature as not to be practically
available.
According to the present invention the purpose aimed at is attained by
manufacturing a colored paper of such a nature that the chemicals employed
for removing writing or other marks in ink from the same, such as acids, chlorine
&c, will destroy or alter the color, the paper thus affording the required safety, as
any attempt to remove or alter the writing will at once become visible thereon.
The requisite operations for the preparation of such paper are at the same time
very simple and do not affect or complicate the ordinary process of manufacturing
paper, as the requisite chemicals need either only be added to the paper material
in the rag engine, or the finished paper may be impregnated therewith. The
method of practically carrying out the invention is as follows:
The prepared paper material is first slightly mordanted with the salt of an iron
oxide (preferably acetate of iron) and is then intimately mixed in the rag engine
with such a quantity of ferrocyanide of lead or other insoluble ferrocyanide
(preferably in a freshly precipitated condition) as will produce the required tint
when the paper is treated with an acid.
If the paper pulp be not entirely free from acid, as is generally the case with
papers having a resinous size, a blue tint will be produced by the formation of
prussian blue.

page_text: This blue tint should be only very slight, in consequence whereof it is expedient
to previously neutralize the acid to a great extent by the addition of carbonate of
soda or other alkali. If, on the other hand, no blue coloration should occur, it
must be produced up to a certain strength, by the addition of sodium ferrocyanide.
The slightly blue coloration can be produced by indigo, either formed on the
paper fibre itself, or used as indigo carmine, or by tinting either with bluish or
redish hues by means of acid fuchsin.
The blue tinting with indigo must not be too strong.
In place of the ferric salt employed for the mordanting, may be substituted,
either partially or entirely, an insoluble iron oxide salt, such as ferric phosphate.
In place of ferrocyanide of lead or of other insoluble ferrocyanide, a soluble
ferrocyanide may be used, in which case the ferric oxide salt must be a ferric
oxide saccharate.
The paper thus prepared will assume a strong blue color on treating it with
acid, prussian blue being formed. On treating it with chlorine and chloride of
lime solutions the color will be partly removed by the destruction of the organic
coloring matter, and on treating it with alkalis or alkali cyanides, a bleaching or
removal of the blue ground color will be effected.
The strength of the blue coloration on acting upon the finished paper with acids
depends upon the amount of the addition of ferrocyanide, which can be determined,
for every case according to the strength of the coloration or the required
sensitiveness of the paper.
Instead of adding the above described substances to the paper material, the
desired result may also be obtained by impregnating the finished paper therewith,
or with the chemicals that serve to produce those substances, applied in proper
sequence, although this would involve greater trouble.

page_text: COMPLETE SPECIFICATION.
I, CHARLES DENTON ABEL, of No 28 Southampton Buildings, Chancery Lane
in the County of Middlesex Consulting Engineer and Patent Agent do hereby
declare the nature of my said invention for "AN IMPROVED MANUFACTURE OF
SAFETY PAPER FOR CHEQUES AND SIMILAR PURPOSES" and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
This invention relates to the manufacture of paper that shall at once indicate
any alteration, effected by chemical means, of writing or other marks made
thereon. The known methods for the production of such safety paper either do
not offer perfect security for the purpose required, on account of the chemical
reagents employed therein, or they are of such a complicated nature as not to be
practically available.
According to the present invention the purpose aimed at is attained by
manufacturing a colored paper of such a nature that the chemicals employed for
removing writing or other marks in ink from the same, such as acids, chlorine &c,
will destroy or alter the color, the paper thus affording the required safety, as any
attempt. to remove or alter the writing will at once become visible thereon.
The requisite operations for the preparation of such paper are at the same time
very simple and do not affect or complicate the ordinary process of manufacturing
paper, as the requisite chemicals need either only be added to the paper material
in the rag-engine, or the finished paper may be impregnated therewith. The
method of practically carrying out the invention is as follows:-
The prepared paper material is first slightly mordanted with the salt of an iron
oxide (preferably acetate of iron) and is then intimately mixed in the rag-engine
with such a quantity of ferrocyanide of lead or other insoluble ferrocyanide
(preferably in a freshly precipitated condition) as will produce the required tint
when the paper is treated with an acid.
If the paper pulp be not entirely free from acid, as is generally the case with
papers having a resinous size, a blue tint will be produced by the formation of
prussian blue.
This blue tint should be only very slight, in consequence whereof it is expedient
to previously neutralize the acid to a great extent by the addition of carbonate of
soda or other alkali. If, on the other hand, no blue coloration should occur, it
must be produced up to a certain strength, by the addition of sodium ferrocyanide.
The slightly blue coloration can be produced by indigo, either formed on the
paper fibre itself, or used as indigo carmine or by tinting either with blueish or
reddish hues by means of acid fuchsin.
The blue tinting with indigo must not be too strong.
In place of the ferric salt employed for the mordanting, may be substituted,
either partially or entirely an insoluble iron oxide salt, such as ferric phosphate.
In place of ferrocyanide of lead, or of other insoluble ferrocyanide, a soluble
ferrocyanide may be used, in which case the ferric oxide salt must be a ferric
oxide saccharate.

page_text: The paper thus prepared will assume a strong blue color on treating it with
acid, prussian blue being formed. On treating it with chlorine and chloride of
lime solutions, the color will be partly removed by the destruction of the organic
coloring matter, and on treating it with alkalis or alkali cyanides, a bleaching or
removal of the blue ground color will be effected.
The strength of the blue coloration on acting upon the finished paper with acids
depends upon the amount of the addition of ferrocyanide, which can be determined
for every case according to the strength of the coloration, or the required
sensitiveness of the paper.
Instead of adding the above described substances to the paper material, the
desired result may also be obtained by impregnating the finished paper therewith,
or with the chemicals that serve to produce those substances, applied in proper
sequence, although this would involve greater trouble.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1, The process of producing safety paper wherein the paper material or the
finished paper is treated with ferric oxide salts and with ferrocyanides insoluble
in water but soluble in acids, such as ferrocyanide of lead or the like on the one
hand, or ferric oxide saccharate and ferrocyanides soluble in water on the other
hand, the paper being afterwards treated with indigo or acid fuchsin.
2, An improved manufacture of safety paper prepared as herein set forth
whereby it has a blue or red color imparted to it of such a nature as to be
altered or destroyed on treatment with chlorine, acids or alkalis.
Dated this 22nd day of T LOOK