Note 1 — Letter from Felipe III to Silva

The reduction of silver ore by amalgamation with mercury was discovered (although mercury had been used long before for obtaining gold) by a Spanish miner in Mexico, Bartholomé de Medina, in 1557. From that time, enormous quantities of mercury have been continually required for the mining operations in the silver-producing districts of Spanish America. Efforts were occasionally made by the Mexican viceroys to procure it in China; but “the Chinese mercury obtained from Canton and Manilla was impure, and contained a great deal of lead; and its price [1782] amounted to 80 piastres the quintal.” See Humboldt’s account, descriptive and historical, of this use of mercury, in his New Spain (Black’s trans.), iii, pp. 250–288.