Where during the progress of a trial a document purporting to be years
old is introduced in evidence, and it can be shown that it is but a
few days old, having been prepared for the occasion, ordinarily the
age of the writing will be comparatively easy of demonstration by the
expert. Oxidization will not have set in to any extent, if the ink is
very fresh, and this, with a careful watching of the color for any
darkening, will determine whether or not the ink is fresh. This ink
study should be a question of the utmost interest to bankers and bank
employes.

A ten-per-cent solution of ammonia applied to two inks in question
will show which is the fresher. The older ink will resist the action
of the ammonia longer and give up less soluble matter than the newer
writing. Nutgall, and logwood inks, of course, should not be tested
comparatively by this method, as the logwood ink will respond to the
ammonia sooner than the nutgall ink.

F. Carré also gives another method for determining, approximately, the
age of ink-writings. If the writing is in iron ink, and is moistened
with a solution of one part of hydrochloric acid to eleven parts of
water and put in letter-copying press and copy transferred to copy
paper it should give a strong copy, if but ten years old; a hardly
legible copy, if thirty years old; and if sixty years old, a few marks
will be copied, but they will not be legible.

If the same solution be used in place of water, as in the ordinary
letter-copying process and the copying paper be saturated with it, the
result will be the same.