The tax, indeed, of the King of Portugal upon the gold of the Brazils is the same with the ancient tax of the King of Spain upon the silver of Mexico and Peru; or one-fifth part of the standard metal. It may, therefore, be uncertain whether to the general market of Europe the whole mass of American gold comes at a price nearer to the lowest for which it is possible to bring it thither, than the whole mass of American silver.
The price of diamonds and other precious stones may, perhaps, be still nearer to the lowest price at which it is possible to bring them to market, than even the price of gold.
Though it is not very probable that any part of a tax which is not only imposed upon one of the most proper subjects of taxation, a mere luxury and superfluity, but which affords so very important a revenue, as the tax upon silver, will ever be given up as long as it is possible to pay it; yet the same impossibility of paying it, which in 1736 made it necessary to reduce it from one-fifth to one-tenth, may in time make it necessary to reduce it still further; in the same manner as it made it necessary to reduce the tax upon gold to one-twentieth. That the silver mines of Spanish America, like all other mines, become gradually more expensive in the working, on account of the greater depths at which it is necessary to carry on the works, and of the greater expense of drawing out the water, and of supplying them with fresh air at those depths, is acknowledged by everybody who has inquired into the state of those mines.
These causes, which are equivalent to a growing scarcity of silver (for a commodity may be said to grow scarcer when it becomes more difficult and expensive to collect a certain
