The fineness is reckoned by carats (not a weight, but a denomination of proportion) for the gold, as the denier is for the silver. Fine gold is said to be, as in England, of 24 carats. The carat is divided into 32 parts, so 32 × 24 = 768, are the parts into which any given mass of gold is supposed to be divided, when we speak of the standard fineness.
The remedy of alloy upon gold.
The standard of French gold is the same with that of silver, to wit, 11⁄12, or 22 carats fine. Upon this the workmen are allowed 12⁄32 parts of a carat, for the Remede d’alloy; which reduces the standard to 210⁄32 carats fine, to 12⁄32 carats alloy. This expressed according to the division above mentioned, stands thus, 692 parts fine to 76 alloy.
To find, therefore, the number of grains of fine gold in a marc of the coin, we must state the following analogy.
768 : 692 :: 4593 : 4138.48.
The marc of gold coin therefore contains, after all deductions, 4138.48 grains of fine gold.
This marc is coined into 30 louis d’ors of 24 livres each, value in all 720 livres.
If therefore 4138.48 grains of fine gold be worth in the coin 720 livres, the marc of fine gold, or 4608 grains, will be worth 801 livres 12 sols.