The examining the bottoms of rivers and the gullies of torrents, and the washing the gold found therein from the sand and dirt with which it is always mixed, are works performed by slaves, who are principally negroes, kept in great numbers by the Portuguese for these purposes. The regulation of the duty of these slaves is singular, for they are each of them obliged to furnish their master with the eighth part of an ounce of gold per diem; and if they are either so fortunate or industrious as to collect a greater quantity, the surplus is considered as their own property, and they have the liberty of disposing of it as they think fit. So that it is said, some negroes who have accidentally fallen upon rich washing places have themselves purchased slaves, and have lived afterwards in great splendour, their original master having no other demand on them than the daily supply of the forementioned eighth, which, as the Portuguese ounce is somewhat lighter than our troy ounce, may amount to about nine shillings sterling. The quantity of gold thus collected in the Brazils, and returned annually to Lisbon, may be in some degree estimated from the amount of the king's fifth. This hath of late been esteemed, one year with another, to be one hundred and fifty arroves of 32 lb. Portuguese weight each, which at £4 the troy ounce, makes very near £300,000 sterling, and consequently the capital, of which this is the fifth, is about a million and a half sterling. It is obvious that the annual return of gold to Lisbon cannot be less than this, though it be difficult to determine how much it exceeds it; perhaps we may not be very much mistaken in our conjecture, if we suppose the gold exchanged for silver with the Spaniards at Buenos Ayres, and what is brought privily to Europe and escapes the duty, amounts to near half a million more, which will make the whole annual produce of the Brazilian gold near two millions sterling, a prodigious sum to be found in a country which a few years since was not known to furnish a single grain.