recoinage it is: Withdraw the worn coins as rapidly (in equal numbers)
as you put new coins into circulation.

The continued circulation of "bad" money along side of "good" money
(light-weight along side of full-weight coins), so long as the total
number of coins is not in excess of the money demand for full-weight
coins, is explained thus on just the same principle as is the
circulation at parity of a light-weight fractional coinage, in the
preceding section.

§ 6. #A general seigniorage charge on standard money.# The fiduciary
coinage problem presents itself under a some-what different guise in
case a seigniorage charge is made on all coinage, even of that metal
used as the standard unit. In this case coinage is free but not
gratuitous. In this case no bullion is brought to the mint unless the
coined pieces the owners receive have a value equal to the bullion
value plus the seigniorage charge. The power to impose a seigniorage
charge is a monopoly power. Artificial limitation is present.
Evidently, the number of coins that can be issued without depreciation
is limited to that number which would circulate if they were made
full weight without a seigniorage charge.[7] This number of pieces of
full-weight metal is the saturation point of the money demand of the
country. If more than that could in any way be put into circulation it
would become worth less as money than as bullion, and would be melted
or exported.

Assume that this full supply of money at a given moment is 100,000
pieces or dollars; then consider the effect of imposing a seigniorage
charge of ten per cent on further coinage. The government alone having
the right of coinage, the need of money would give the circulating