renders their edges less well defined.

Even on well-sized papers this class of inks usually exhibits only a
stained line of no appreciable thickness where the fluid has touched
the paper.

The copying and glossy inks, which often contain a considerable
quantity of gum, do not "run" or blot even on partially sized paper,
and show under the glass a convexity on the surface of the line and an
appreciable thickness of the film.

It does not always follow when an ink has made a blur on one part of
the paper and not on another that the paper has been tampered with. A
drop of water accidentally let fall on the blank page will frequently
affect the sizing in that place, and, besides, all papers are not
evenly sized in every part.

The inks rich in gum, or those concentrated by evaporation from
standing in an open inkstand, give a more lustrous and thicker stroke.
Some inks penetrate deeper into the paper than others, and some
produce chemical effects upon the sizing and even upon the paper
itself, so that the characters can easily be recognized on the
underside of the sheet. In some old documents the ink has been known
to so far destroy the fiber of the paper that a slight agitation of
the sheet would shake out as dust much of the part which it covered,
thus leaving an imperfect stencil plate of the original writing.

Distilled water is very useful in many cases to ascertain whether
paper has been scratched and partially sized or treated with resin. If
it has not been altered by chemical agents, the partial sizing and the