W. C a r e w H a z l i t t Coinage of the European Continent

64 The Coins of Europe
more particularly where gold and silver are concerned ;
but
billon and copper coins have to be treated with great
tenderness, and while ammonia and other chemical appliances
to restore to their
may be employed by proficient persons
original state specimens in the more precious metals, their
use in other cases is
apt to produce unsatisfactory results, if
not positive disaster. Where the dirt, accumulated by time
on old gold or silver money, is loose, its disappearance is
certainly advantageous and agreeable to the eye, and the
injury to the tone of the surface or to the patina is temporary.
But there is a very broad distinction between tone and
discoloration by soil ;
and where a coin of early date has
acquired genuine patination,
it should on no account be
disturbed, unless it be, perhaps, by the softest possible brush,
where particles of dust have filled up the characters of the
legend or the details of the type.
One word more in the way of caveat is requisite under
this head. Old coins frequently present themselves in a
more or less worn condition with bright fields or surfaces,
which to an experienced eye offer a rather painful contrast
to the remainder. These pieces have been tooled and
burnished by modern hands, and are materially impaired in
value by the process. Their purity has been irretrievably
destroyed.
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The reader will observe that the work in his hands
divides itself into four portions
: the Introduction ;
the Two
Catalogues ;
the Descriptive Text. In the first an endeavour
has been made to survey the whole field, and to assist the
student, before he proceeds farther, in forming as accurate a
notion as possible of its extent, its character, and its claims.
The Catalogues, which are taken to be infinitely more
complete than anything of the same kind hitherto procurable
in English and in one corpus, embrace a very considerable
amount of information, calculated to be serviceable and
interesting, upon many matters of technical and even of