125. It must, however, be admitted that the principle of
copying itself furnishes an expedient for imitating any engraving
or printed pattern, however complicated; and thus presents a
difficulty which none of the schemes devised for the prevention
of forgery appear to have yet effectually obviated. In attempting
to imitate the most perfect banknote, the first process would be
to place it with the printed side downwards upon a stone or other
substance, on which, by passing it through a rolling-press, it
might be firmly fixed. The next object would be to discover some
solvent which should dissolve the paper, but neither affect the
printing-ink, nor injure the stone or substance to which it is
attached. Water does not seem to do this effectually, and perhaps
weak alkaline or acid solutions would be tried. If, however, this
could be fully accomplished, and if the stone or other substance,
used to retain the impression, had those properties which enable
us to print from it, innumerable facsimiles of the note might
obviously be made, and the imitation would be complete. Porcelain
biscuit, which has recently been used with a black lead pencil
for memorandum books, seems in some measure adapted for such
trials, since its porosity may be diminished to any required
extent by regulating the dilution of the glazing.
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