The journals Ruiz produced for his exploration of South America during these years are remarkable for their breadth of ethnobotanical and natural history knowledge. Of particular interest at the time was pharmacological knowledge of New World plants such as Chinchona, the source of the anti-malarial, quinine. In addition to detailed descriptions and paintings of the flora and fauna of Peru and Chile, Ruiz observed the geology and weather of the area, and included cultural information about the life of the Indians and the colonists of the area. The result of these observations was the publication of Quinología o tratado del árbol de la quina in Madrid, 1792, that was promptly translated into Italian in 1792, German in 1794 and English in 1800.
