Erasures in parchments produce prominences on the opposite side of the
sheet. The ink placed upon such erasures has a peculiar bluish tinge.
It happens at times that a whole page is taken out, either by
scratching or rubbing with pumice (which was the practice in the
eleventh century, when a parchment became so valuable that it was
common to keep up the supply by erasing the writing on old parchments)
or by washing.

When the latter method was used, the writing as in palimpsests can be
made to reappear by warming. The parchment can be either laid on a hot
plate or pressed with a hot flatiron between two sheets of paper.

Where the supposed writer of a document was a bad or careless penman
the interlineations or additions are generally distinguished from his
handwriting, which they simulate, by greater clearness and precision,
as has been said above; for when a man will risk being sent to jail
for forgery it is not likely that he is willing to lose any
prospective advantage which his felony will bring him by lack of
distinctness in the characters by means of which it is perpetrated.

Considering the number of fraudulent additions or interlineations
which are constantly made, the number of mistakes in spelling or in
following the method employed by the supposed writer in forming the
same words is surprisingly great. Several instances are recalled where
the name of the supposed writer was not only mispelled but spelled in
two different ways in the same instrument. It occasionally seems as if
the forger's attention is so earnestly directed to overcoming the
difficult parts of his task that he neglects the simpler and more
obvious parts. A forger generally leaves some telltale marks to make