pected
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
inexperienced amateurs.

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
pie