To determine the age of writing by applying bleaching acids and
watching results and counting the seconds is a dangerous method. Thick
inks will respond to the acids slower than thin, and the time
comparisons are misleading.

Safety inks, so-called, designed to resist the action of acids and
alkalies have been repeatedly put upon the market, but no such ink has
ever successfully challenged the world and proved its title of safety.

Many chemicals are recommended as restorations for faded writing, but
these should be avoided as far as possible, as they are liable to
stain, disfigure the paper, and in the end make matters materially
worse. Familiarity with particular handwritings after some practice
will enable the reader to make out otherwise unintelligible words
without any other assistant than a powerful magnifying glass.

If the ink is very faint, the simplest and most harmless restorative
is sulphate of ammonia, but its loathsome smell once encountered is
not easily forgotten. The experiment in consequence is very seldom
repeated for the result is scarcely good enough to risk a repetition
of so horrible a smell.

The writing on old and faded documents may be restored, by chemical
treatment, turning the iron salt still remaining into ferrous sulphate.
A process which will restore the writing temporarily is as follows: A
box four or five inches deep and long and broad enough to hold the
document, with a glass, is needed. A net of fine white silk or cotton
threads is stretched across the box at about one half the depth. Two
saucers containing yellow ammonium hydrosulphide are placed in the
bottom of the box. By means of a clean sponge or brush, moisten the