The ducat has no legal denomination.
The ducat is what they call a negotie pfenning, that is, a coin struck under the authority of the state, in all the mints, and of a determinate weight and fineness; but not a legal money in payments, because it has no legal denomination.
Ducats are delivered by the marc weight as the silver; but there is a remedy of weight deducted of one engle per marc. So the marc of ducats, as delivered by the mint, weighs but 5088 aces.
The fineness 23 carats 8 grains.
The fineness of the ducats is (as in the empire) of 23 carats 8 grains; but in Holland they allow one grain of remedy.
The standard of the gold is reckoned by carats and grains: 24 carats are called fine gold, and every carat is divided into 12 grains; so let the mass of gold be of what weight soever, it is always supposed to contain 288 parts, that is, 12 × 24: at this rate the fineness of ducats is 283 parts fine gold, and 5 parts alloy.
Fineness of the ducats of the empire.
The imperial ducats ought to be 284 parts fine, 3 parts silver, and one part copper, without any remedy; but in Holland the assayers bring the gold to the fineness of 23 carats and 8 grains; then they suppose that what remains is all silver, and they take their remedy by adding one grain of copper. Dutch ducats are therefore something in the fineness, though nothing in the weight below the regulations of the empire.
Exact quantity of fine gold in a marc weight of Dutch ducats as they come from the mint.