To find the number of grains of fine gold in the marc weight, as it is delivered from the mint, we must state this proportion,
288 : 283 :: 5088 : 4999.6.
The marc, therefore, of gold coined into ducats, after all deductions for alloy, and for the remedies of weight and fineness, contains 4999.6 aces of fine gold. This marc is ordered to be coined into 70 ducats.
If, therefore, 4999.6 aces of fine gold, be worth 70 ducats, then the full marc of 5120 aces of fine gold will be worth 71.687 ducats, by this proportion, 4999.6 : 70 :: 5120 : 71.687.
But the mint price of the marc of fine gold is 71 ducats.
The difference, therefore, between the value of a marc of fine gold in ducats, and the price given by the mint for the same quantity of fine gold bullion, shews the expence of coinage. State thus,
| Price of the marc of fine gold in ducats | 71.687 | ducats |
| Mint price of the marc ditto | 71 | |
| Price of coinage | 0.687 |
To know how much this makes per cent. state thus,
71 : 71.687 :: 100 : 100.96.