Examination for determining whether a writing has been done at one time,
or added to later, necessitates some acquaintance with the nature and
qualities of ink. In the ordinary case the assistance of a chemist is
necessary, but an enlarged photograph shows up minute differences with
In the majority of instances alterations are made some time after the
original has been written, in which case a difference in the shade of
the ink will be perceptible, even to the unassisted eye. This is
particularly true when the now almost universal blue-black ink is used.
The period required for an addition to become as black as the older
writing depends very much upon the character of the paper. If this be
smooth and hard, and the writing has not been dried with blotting paper,
but allowed to dry naturally and slowly, it will become black much
quicker than if the paper be rough and of an absorbent nature.
A fairly reliable test is to touch a thick stroke of the suspected
addition with a drop of diluted muriatic acid--as much as will cling to
the point of a pin. Apply the drop to the suspected addition and to the
older writing at the same moment, and carefully watch the result. The
newer writing will become faint and watery, with a bluish tinge almost
instantly, but the change will be slower in the case of the older
writing, taking ten or even twenty seconds. The longer the period
required for the change, the older the writing.
This same acid test is applied to prove whether a writing is in ordinary
ink, or has been lithographed or photographed. If the two latter, the
acid will have no effect.
On more than one occasion collectors have purchased as original
autographs of celebrities which proved to have been lithographed or
photographed, but the persons so deceived have generally been
When the difference between a written and printed signature has been
once noticed it is hardly likely that an observant person will be
deceived. It is, however, as well to be carefully on guard against this
contingency, for modern photography and process printing have been
brought to such a degree of imitative perfection that it is easy for a
not too keen-eyed person to experience great difficulty in forming an
opinion in the absence of the acid test. Fortunately that is infallible.
It must, however, be admitted that up to the present no great success
has attended efforts to determine how long an interval has passed
between the writing of the original and the suspected addition. Broadly
speaking, the most that the expert can hope to gain from an examination
of ink under these circumstances are hints, clues and suggestions rather
than definite, reliable facts. Fortunately it often occurs that a
suggestion so obtained proves of immense value to the trained or careful
observer, though it might convey no conviction to others.
As in the case of nearly all deductive reasoning the handwriting expert
becomes sensitive to slight suggestions. If called upon, as he sometimes
is, to explain to others how and why one of these slight and almost
imperceptible signs fit in with his theory, he fails. Therefore the
cautious expert, like a good judge, is careful in giving reasons for his
judgment only to cite those which are self-evident.
Many an expert has made a poor exhibition in the witness-box by failing
to convey to a jury the impression produced on his own mind by a slight
piece of evidence, the proper understanding and interpretation of which
can only be grasped by those who have learned how to recognize faint
The process of chemically testing inks for the purpose of ascertaining
the points mentioned is quite simple, and is distinctly interesting. In
a very important case the services of a qualified chemist will probably
be requisitioned, but the cost of the necessary material and the time
required to make oneself proficient as a capable tester are so slight
that even the small fee that would be charged by a chemist is scarcely
The materials necessary are a few test tubes, some bottles of lime
water, diluted muriatic acid, a solution of nitrate of silver in
distilled water, in the proportion of ten grains to the ounce, some
camel hair pencils, and clean white blotting and litmus paper. The whole
need not cost more than half-a-crown.
The method of using these materials is best illustrated by describing a
test often needed by autograph collectors.
A very common method employed by forgers to give an appearance of age to
the ink used in spurious old documents is to mix with ordinary ink,
muriatic acid, oxalic acid, or binoxalate of potash. The presence of
these colouring agents can be detected in the following manner.
In the first place, washing the letter with cold water will make the ink
become darker if acid has been used to brown the ink, but the following
test will settle the point beyond dispute:
With a camel's-hair brush wash the letter over with warm water. If, as
sometimes happens, a sort of paint or coloured indian ink has been used,
this will be immediately washed away and disappear, leaving a rusty
smudge. If not, apply the litmus paper to the wetted ink, and the
presence of acid will be shown in the usual way by the litmus paper
changing colour. If genuine, wetting makes no difference.
Next, pour a drop or two of the water from the writing into a test tube
from off the letter, add a little distilled water and one or two drops
of the nitrate of silver solution.
If muriatic acid has been used to colour the ink, a thick white
precipitate will be seen in the tube immediately.
If not, pour a few more drops of the water which has been washed over
the writing into a second test tube, add a little distilled water and a
few drops of lime water. A white precipitate will be seen in the tube if
either oxalic acid or binoxalate of potash has been employed.
In many cases it will be sufficient to place the tip of the tongue to a
thick stroke. An unmistakable acid taste will be noticed.
Further and fuller particulars of the methods resorted to by forgers to
simulate ancient documents will be given in the chapter on Autographs.
It is sometimes important to know whether a stroke has been made over
another, as in the famous case in which the real issue turned on the
question whether an apparent alteration in a signature was really a
pen-mark made to indicate where the signatory should sign. It was
obvious that if the mark was made first the signature would be over it;
if, as was suggested, the mark was added in an attempt to alter or touch
up the signature, it must have been written over the signature.
In cases of this kind an enlarged photograph leaves no room for doubt.
The ink is seen lying over the lower stroke as plainly as a layer of
paint in a picture can be seen overlying the stroke beneath.
This is one of those apparently difficult points which become
marvellously simple when dealt with in a practical manner.
Pages might be needed to explain what a very simple experiment will
reveal at a glance.
Take a word which has been written long enough for the ink to have
become dry, and make a stroke across it. For example, make a letter _t_
without the bar, then, after a lapse of an hour or two, add the cross
bar. When this is quite dry and has become as dark as the first mark,
examine it with a good glass. The ink of the added bar will be seen
plainly overlaying the vertical stroke, but any doubt can be promptly
removed by taking an enlarged photograph.
Even when the second stroke is added while the ink on the first is still
wet the upper stroke can be distinguished, though not so clearly as if
the first stroke had been allowed to dry first.
By practising and examining such strokes, the student will soon learn to
distinguish important signs which leave no doubt as to which stroke was
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