QUASSIA, the generic name given by Linneeus to a small tree of Surinam in honour of the negro Quassi or Coissi, who employed the intensely bitter bark of the tree as a remedy for fever. This bark was introduced into European medicine about the middle of the last century, and was officially recognized in the London Pharmacopaia of 1788. In 1809 it was replaced by the bitter wood or bitter ash of Jamaica, Picrana excelsa, Lindl., which was found to possess similar properties and could be obtained in pieces of much larger size. Since that date this wood has continued in use in Britain under the name of quassia to the exclusion of the Surinam quassia, which, however, is still employed in France and Germany. Picrxna excelsa, Lindl. (Quassia excelsa, Swartz) is a tree 50 to 60 feet in height, and resembles the common ash in appearance. It has imparipinnate leaves composed of four or five pairs of short-stalked, oblong, blunt, leathery leaflets, and inconspicuous green flowers. The fruit consists of shining drupes about the size of a pea. It is found also in Antigua and St Vincent. Quassia amara, L., is a shrub or small tree belonging to the same natural order as Picrxna, viz., Simarubacex, but is readily distinguished by its large handsome red flowers arranged in terminal clusters. It is a native of Panama, Venezuela, Guiana, and northern Brazil. Jamaica quassia is imported into England in logs several feet in length and often nearly one foot in thickness, consisting of pieces of the trunk and larger branches. The thin greyish bark is usually removed. The wood is nearly white, or of a yellowish tint, but sometimes exhibits blackish markings due to the mycelium of a fungus. The wood has a pure bitter taste, and is without odour or aroma. It is usually to be met with in the form of turnings or raspings, the former being obtained in the manufacture of the "bitter cups" which are made of this wood. The medicinal properties are due to the presence of quassiin (first obtained by Winckler in 1835), which exists in the wood to the extent of Muth per cent. It is a neutral crystalline substance, soluble in hot dilute alcohol and chloroform and in 200 parts of water. It is also readily soluble in alkalies, and is reprecipitated by acids. It is almost insoluble in ether, and forms an insoluble compound with tannin.
Quassia is used in medicine in the form of infusion and tincture as a pure bitter tonic and febrifuge, and in consequence of containing no tannin is often prescribed in combination with iron. An infusion of the wood sweetened with sugar is also used as a fly poison, and forms an effectual injection for destroying thread worms. Quassia also forms a principal ingredient of several "hop substitutes," for which use it was employed as long ago as 1791, when John Lindsay, a medical practitioner in Jamaica, wrote that the bark was exported to England " in considerable quantities for the purposes of brewers of ale and porter."