A philosophical and practical essay on the gold and silver mines of Mexico and Peru : Containing the nature of the ore, and the manner of working the mines; the qualities and use of quicksilver; the cleansing and refining these metals: With many useful observations concerning the assay of metals, the manner of conveying them to Europe; and remarks on the gold mines in Hungary, and those of Asia and Africa. Translated from a letter wrote in Spanish, by Father James Hernandez of the Society of Jesus; employed by His Catholic Majesty to write the natural history of the West Indies.