BENZOIN GUM, or Gum Benjamin (supposed to be from Arab. luban, frankincense, the first syllable being dropped in Romanic as if it were the article), a balsamic resin obtained from Styrax benzoin, a tree of considerable size, native to Sumatra and Java, and from other species of Styrax. It is obtained by making incisions in the bark of the trees, and appears to be formed as the result of the wound, not to be secreted normally. There are several varieties of benzoin in commerce: (1) Siam benzoin, which apparently does not come from Styrax benzoin, is the finest and most aromatic, and occurs in the form of small "tears," rarely exceeding 2 in. in length by in. in thickness, and of "blocks" made up of these tears agglomerated by a clear reddish-brown resin. The odour of Siam benzoin is partly due to the presence of vanillin, and the substance contains as much as 38% of benzoic acid but no cinnamic acid. (2) Sumatra benzoin occurs only in masses formed of dull red resin enclosing white tears. It contains about 20% of cinnamic acid in addition to 18 or even more of benzoic. (3) Palembang benzoin, an inferior variety, said to be obtained from Styrax benzoin in Sumatra, consists of greyish translucent resinous masses, containing small white opaque tears. It does not appear to contain cinnamic acid. Large quantities of benzoin are used as incense. Its medicinal uses depend on the contained benzoic acid (q.v.).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)