“There are in the suburbs of Rome,” says _Cosmos_, “two
farms where antique medals are made in large quantities. This
would seem to be a singular agricultural product, yet nothing
is more exact. The people who devote themselves to this odd
industry cause to be swallowed by turkeys coins or medals
roughly struck with the effigy of Tiberius or Caligula. After
remaining for some time in the bodies of the fowls, the little
disks of metal become coated with a remarkable ‘patina.’ If this
coating were only the result of the gastro-intestinal voyage,
it would be easy to secure it by treating the coins to be aged
with dilute hydrochloric acid, for instance. But the mechanical
action of the tiny stones contained in the gizzard is added
to the purely chemical action of the gastric juice, partially
effacing the figures and toning down the hardness of the
features. It is to be feared that some of the specimens in our
public collections have been obtained by this curious process.”
(47)