Cinchona in the year 1851. Mr. [Thaddäus] Haenke mentioned the existence of cinchona bark on his visit to Yuracares in 1796". (Source: Exploration of the Valley of the Amazon, by Lieut. Lardner Gibbon, USN. Vol.II, Ch.6, pp. 146-47.) The cultivation of cinchona led from the 1890s to a decline in the price of quinine but the quality and production of raw bark by the Dutch in Indonesia led them to dominate world markets. The producers of processed drugs in Europe (especially Germany) however bargained and caused fluctuations in prices which led to a Dutch-led Cinchona Agreement in 1913 that ensured a
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