ce of evidence, the proper understanding and interpretation of which
can only be grasped by those who have learned how to recognize faint
signs.

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
worth paying.

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