If, by the exportation of all the heavy coin of London, bills must be paid in a worn out currency, the rise in the price of gold in their market, above mint price, will mark pretty nearly how far it is light.
If, on the other hand, the wars of France, or an unfavourable balance upon her trade, shall oblige her to export her coin, that operation will sink the value of it, or raise the price of bullion, which ever way you choose to express it.
It is not here a proper place to resume the question, which of the two expressions is the most proper: we are here considering the value of the bullion as what is fixed, because it answers the purpose. But whether we say that bullion rises in the markets of Paris and London; or that the value of their currencies sink, though from very different causes, the calculation of the real par will proceed with equal accuracy. An example will illustrate this.
When fine gold is at the lowest price to which it can ever fall at Paris, that is to say, at the mint price, it is worth 740 livres 9 sols, or 740.45 livres per mark, in decimals, for the ease of calculation. The mark contains eight ounces Paris weight.
Were the ounces of Paris equal to those of troy weight, ⅛ of this sum, or 92.5562 livres, would be the value of that ounce by which gold is sold at London.
But the Paris ounce is about 1½ per cent. lighter than the troy ounce; and the exact proportion between them is unknown, from the confusion of weights, and the want of a fixed standard in England.
By the best calculation I have been able to make, a Paris ounce should contain 473 grains troy, which makes the proportion between the two ounces to be as 473 is to 480, which is the number of grains in the troy ounce.
Gold bullion at Paris is regulated by the mark fine, at London by the ounce standard.
When standard gold bullion is at the lowest price it can be at London, it is worth the mint price, or 3l. 17s. 10½d. per troy ounce, which, expressed in decimals, is 3.8937l. sterling. Standard is to fine, as 11 is to 12; consequently, the ounce fine is 4.2476l. sterling: and if the Paris ounce of fine bullion be worth, as has been said, 92.5562 livres, the ounce troy, according to the above proportion, will be worth 93.926 livres. Divide then the livres by the sterling money, and the quotient will give you the real par of exchange of the pound sterling, while bullion remains at that value in Paris and in London, viz. 4.2476⁄93.926 = 22.112 livres for the pound, or 32.56d. sterling for the French crown of 3 livres.
Gold bullion never can rise in the Paris market, at least all the last war it never did rise, above the value of the coin; that is, to 801.6 livres the mark fine, or 100.2 livres per ounce Paris, and 101.7 livres the troy ounce.