The Titre or title, as the French call it, or the standard of their silver coin, is 11 parts fine to 1 part alloy. At this rate we shall find in this Marc of coin, consisting of 4572 grains standard silver, 4191 grains of fine silver, and 381 grains of alloy.
But the workmen have also an allowance of 3 grains upon the fineness, which introduces a new equation.
The mass of silver in the French mint (when we speak of the fineness) is supposed to be divided into 12 deniers, and every denier into 24 grains; which, in this acceptation, are both denominations of proportion, not of weight.
Any mass of silver, therefore, of whatever weight, must be supposed to contain 12 × 24 = 288 grains of proportion; consequently, were the standard exactly 11 deniers fine, the proportion would be marked thus, 264 grains fine, to 24 alloy; but since there is an allowance of 3 grains of proportion, called le remede d’alloy, this brings the proportion to be as 261 is to 27. This is the exact standard of French silver coin, and answers to 10 deniers and 21 grains fine, which is the term used in the mint.
To find, therefore, the number of grains of fine silver in a marc of the French silver coin, we must state this proportion, 288 : 261 :: 4572 : 4143.38.
Quantity of fine silver in a marc, as delivered at the mint.
The marc, therefore, of coined silver, after all deductions for alloy, and for remede de poids, contains of fine silver 4143.38 grains poids de marc.
This marc is coined into 8 great crowns and 3⁄10 of a crown, value in the coin 49 livres, 16 sols.