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Kino is the name of the plant gum produced by various plants and trees, particularly Eucalyptus, in reaction to mechanical damage, and which can be tapped by incisions made in the trunk or stalk. Its red colour, together with the tendency of some species to ooze large amounts of it from wounds, is the source of the common names "red gum" and "bloodwood". The word “kino” is of West African origin.
Composition
Astringent tannin compounds are a major active component of kinos. The chief constituent of kino is kinotannic acid, of which it contains 70 to 80 per cent. It also contains kino red, a phlobaphene produced from kinotannic acid by oxidation. Kino also yields kinoin, a crystalline neutral principle.
In cold water it is only partially dissolved, leaving a pale flocculent residue which is soluble in boiling water but deposited again upon cooling. It is soluble in alcohol and caustic alkalis, but not in ether.
When exuding from the tree, it resembles red-currant jelly, but hardens in a few hours after exposure to the air and sun. Kinos typically dry to an amber-like material. It consists of dark red angular fragments, rarely larger than a pea. Of the small angular glistening fragments, the smaller are reddish, and the larger are almost black; thin pieces are ruby red. It is brittle and easily powdered. It has no smell, but a very astringent taste.