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chloride； orange； tartar…emetic； red； and if the
marks are faded ones； solutions of sulphate of iron
or bichromate of potash will restore them respectively
to a violet or blue…black color。
Prussian blue； aniline blue and indigo blue are to
be tested as follows： Solution of chloride of lime； no
change of color for prussian blue； decoloration or
faint yellow for aniline blue or indigo。 To discriminate
between the two latter； test with solution of
caustic soda； when decoloration or change of color
will indicate aniline blue and permanence will indicate
presence of indigo blue。
In the manufacture of the blue…black inks； a variety
of violets have been and are still employed。 Among
them are aniline violet； iodine violet； madder； alkanet；
orchil and logwood。
（a） Apply chloride of lime solution： 1。 No change
of color indicates alkanet。 2。 Any change； one of
the other five。
（b） Apply lemon juice： 1。 The violet becomes
brighter if it is one of the aniline violets； to be
distinguished from each other by applying one part of
hydrochloric acid to three parts of water； when it will
become violet…blue； changing to red if it is common
aniline…violet； but blue changing to a green hue and
upon adding plain water to a lilac or pearl gray if it
is iodine…violet （Hoffman's）。 It will also turn from
red to yellow in lemon juice。 To test for the other
three violets： （a） Apply chloride of lime； to be followed
by a solution of yellow prussiate of potash：
absence of a blue coloration leaves orchil and logwood
to be considered。 To distinguish between them apply
solution of hydrate of lime； whereby a change to
gray； followed by complete decoloration indicates logwood；
and a change to violet…blue； orchil。
The substances utilized with but few exceptions for
red ink are the 〃eosins；〃 possessing different names
like erythrosine； as well as different hues。 Antecedent
to about thirty…five years ago； cochineal （known
as 〃carmine〃）； madder； Brazil wood and saffron formed
the basis of most of the red inks。
Make a soap solution adding a small quantity of
ammonia； lemon juice； muriate of tin； all in water：
1。 No change upon application indicates madder。
2。 Any change； the presence of one of the three other
reds： （a） thus a complete decoloration with a return
of the color indicates saffron； （b） reappearance of the
red color though weaker； aniline…red： （c） production
of a yellowish red or light yellow color； cochineal or
Brazil wood； to be distinguished from each other by
the application of concentrated sulphuric acid； when
Brazil wood will at once give a bright cherry…red； and
cochineal a yellowish orange。
No yellow inks are in commercial use。 Documents
do； however； often contain yellow marks about which
information is required as to their origin。 As a rule
they are iron rust； picric acid； turmeric； fustic； weld；
Persian berries or quercitron。 In order to recognize
the different colors； the presence or absence of iron
rust and picric acid must first be determined。
Apply a warm sample of a slightly acid solution of
yellow prussiate of potash； iron rust will be indicated
by a blue coloration。
Apply a weak solution of cyanide of potassium； picric
acid will yield a blood…red coloration。
If picric acid and iron rust are both absent； apply a
bit of ordinary wetted soap： 1。 It turns reddish…brown
and becomes yellow again with hydrochloric acid
turmeric； 2。 It turns quite darkfustic； 3。 It is
unaffectedweld； Persian berries or quercitron。 To
distinguish between these three； apply sulphuric acid；
the color of weld will disappear； and of the others
remaining apply tin…salt solution； when a change to
orange indicates Persian berries； and no change or a
very slight one； quercitron。
Inks containing also logwood； fustic； Brazil wood；
or madder； were all of them more or less employed
some years ago。 Their color phenomena； following
long periods of time； is much the same。 Tests as prescribed
in the accompanying table for such inks will
serve to classify them preliminary to subsequent and
more certain ones。
LOGWOOD。 FUSTIC。
Concentrated Hydrochloric Acid Red…yellow Red
Dilute 〃 〃 Reddish Yellow…Brown
Concentrated and dilute Nitric Acid Red Red…Yellow
〃 Sulphuric Acid 。 。 Black Dark Purple
Dilute 〃 〃 Red Brown Purple
Potassium Chromate 。 。 。 。 Black
Stannous Chloride Violet Yellow
Tartaric Acid 。 。 。 。 。 Gray…Brown Yellow
Sulphate of Copper 。 。 。 。 Dark Gray
Tannin 。 。 。 。 。 。 Yellow…Red Yellow
Potash Dark Red Yellow
Potassium Permanganate Light…Brown Yellow
〃 Iodide 。 。 。 。 。 Red…Yellow
Pyrogallic Acid 。 。 。 。 Yellow…Brown Yellow
Chrome…yellow 。 。 。 。 。 Dark Violet
Sodium （Salt） Violet Red
Sulphate of Iron Gray to Black
Alum 。 。 。 。 。 。 。 Violet Red；Brown。 Faint Red
BRAZIL WOOD。 MADDER。
Concentrated Hydrochloric Acid Light Red Pale Yellow
Dilute 〃 〃 Light Red Pale Yellow
Concentrated and dilute Nitric Acid Dark Purple Pale Yellow
〃 Sulphuric Acid 。 。 Red Pale Yellow
Dilute 〃 〃 Purple Pale Yellow
Potassium Chromate 。 。 。 。 … …
Stannous Chloride Light Red Light Red
Tartaric Acid 。 。 。 。 。 Red Yellow Pale Yellow
Sulphate of Copper 。 。 。 。 … …
Tannin 。 。 。 。 。 。 No Change Pale Yellow
Potash Crimson Light Red
Potassium Permanganate … …
Iodide 。 。 。 。 。 … …
Pyrogallic Acid 。 。 。 。 … …
Chrome…yellow 。 。 。 。 。 … …
Sodium （Salt） … Red
Sulphate of Iron Dark Violet …
Alum 。 。 。 。 。 。 。 … Faint Red
CHAPTER XIX。
FRAUDULENT INK BACK GROUNDS。
DETECTION OF ALTERATIONS IN DOCUMENTS BY CHEMICAL
TESTS WHICH APPLY SOLELY TO THE PAPERACCURACY
OF RESULTS OBTAINED BY USE OF IODINE
EXCELS THAT OF ALL OTHER CHEMICALSIT APPLIES
BEST TO LINEN PAPERMODERN HARD PAPER DOES
NOT GIVE COMPLETE INFORMATIONEFFECT OF IODINE
ON MARKS MADE BY A STYLUS OR GLASS PEN。
FIFTY years ago and long before the employment of
the fugitive 〃anilines〃 for ink uses； and 〃wood
pulp〃 as a material for paper； two French chemists；
Chevallier and Lassiagne； published in the Journal de
Chimie Medical； an article 〃On the Means to be
Employed for Detecting and Rendering Perceptible
Fraudulent Alterations in Public and Private Documents；〃
which as translated is valuable enough to
quote in full：
〃The numerous experiments which have been
already tried at various times； have made known
the processes which may frequently be put in practice
for causing the reappearance of traces of writing
effaced by chemical reactions； and for throwing
light on the work of the guilty。 But there are
cases in which all the means proposed for this purpose
fail； and then the criminal may escape justice
from the want of conclusive material proofs。 If；
as has already been proved； it is not always possible
to cause the reappearance of the effaced writing；
for which written words have with a fraudulent
intent been substituted； at least； as our
experiments demonstrates； we may recognize； by
some effects which are manifest on the surface of
the altered paper； the places where the criminal act
has been performed； circumscribe them by a simple
chemical reaction visible to the least practiced eye；
and even measure their extent。 In a word； the
visible alterations produced on a deed are susceptible；
owing to the partial modifications which the
surface of the paper has undergone； of being differently
affected by certain chemical actions； and
of being rendered visible。 The following experiments；
made in a judicial investigation； furnish us
with the following facts：
〃1st。 The surface of paper sized in the ordinary
way； or letter paper； no longer presents with certain
reactions； the same uniformity where it has
been either accidently moistened in several places
by various liquids； or left in contact for a certain
time with agents capable of removing or destroying
the characters which have been traced on it with
ink。
〃2d。 The application of a thin layer of gum； of
starch； or farina； of ge