Quinine the Quechua, who are indigenous to Peru, Bolivia and Ecuador, to halt shivering due to low temperatures. The Quechuas would mix the ground bark of cinchona trees with sweetened water to offset the bark's bitter taste, thus producing tonic water. The Jesuits were the first to bring cinchona to Europe. The Spanish were aware of the medicinal properties of cinchona bark by the 1570s or earlier: Nicolás Monardes (1571) and Juan Fragoso (1572) both described a tree that was subsequently identified as the cinchona tree and whose bark was used to produce a drink to treat diarrhea. Quinine has been
Bark pocket indicator of air pollutants during which the time they formed. They can be used to monitor heavy metals such as lead and copper, as dust or other matter deposited on the bark at the time of formation is still present. One study analysed the amount of polycyclic aromatic hydrocarbons (PAHs) present in bark pockets as a historical record of air quality, possible due to the interaction between PAHs and lipids in the bark. Bark pocket Bark pockets can be formed by inosculation, formation of a tree fork, encapsulation of a branch, joining together of an uneven trunk, or encapsulation of