f unequal thickness, the writing paper of the
period being much smoother and finer than the printing paper, while in
parts it is almost certain the ink has run, as it does on a coarse,
absorbent paper. This is a sure sign that the paper is printing and not
writing.

Further, such paper is certain to show signs of wear at the bottom edges
where they have been handled and exposed, while that part of the page
which has been closest to the inside edge of the cover is generally
cleaner, and shows less sign of wear. In many cases the impression of
the book binding is plainly visible.

A careful examination and comparison of a few sheets of genuine letter
paper of the seventeenth and eighteenth centuries with the blank leaves
found in printed books will reveal differences so marked that mistake is
scarcely possible afterwards.

It often occurs that grease marks interrupt the forger. Knowing that he
cannot write over them, and that they are hardly likely to have existed
on the paper when it was new, and when the letter was supposed to be
written, he avoids them. The result becomes apparent in unequal spacing
of words and even letters.

On one occasion a really excellent forgery, which had successfully
withstood all the tests we had applied, had its real character revealed
by a curious oversight on the part of the forger.

It was an early seventeenth century document, and our attention was
arrested by a peculiar uniform smudgy appearance, such as results from
blotting with a hard, unabsorbent, much-worn sheet of blotting paper. At
the period of the presumed date of this document blotting paper was
unknown, writings being dried by means of a specially prepared fine
powder called pounce, sand, or a powder containing fine crystals of
metal intended to give an ornamental gloss to the ink. Close examination
under the microscope revealed the truth. There were no signs of pounce
or any other drying powder, the crystals of which are usually plain to
the unassisted eye, but there were distinct signs of the fibre of the
blotting paper left in the ink.

Another forgery we discovered through the presence in the centre of the
sheet of paper of a very faint square outline which enclosed a slight
discolouration. The sheet had, as usual, been removed from a book, and
the square outline was a faint impression of a book-plate which had been
affixed to the opposite page. The discolouration was caused by the ink
on the book-plate.

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