Siam Benzoin

#### Benzoin Siam. **Siam**** ****Benzoin**** **is a natural gum-resin or, more correctly, a "balsamic resin" (see **Gum**** ****Resin**** **and definitions, Part One of this book). The resin is obtained from the small tree, **Styrax**** ****Tonkinensis**, a native of Indochina (Laos and Tonkin). Other species are known to yield similar gum-resins called Siam benzoin. The balsamic latex flows from wounds in the bark and outer wood where incisions are made deliberately. **Benzoin**** **is thus a pathologic product (it does not occur in healthy, unwounded trees). It is furthermore characteristic that not all of the benzoin trees will yield a latex after incisions. The milky latex solidifies by oxidation and exposure to air and sunlight. When the benzoin is collected, it is already semi-solid, and it soon becomes hard and brittle, yellow-reddish or orange colored to pale brown, often translucent (thus differing from **Sumatra **types of benzoin). The name **Siam**** **is attached to this type of benzoin merely because of the fact, that the merchandise is often exported via Siam (Thailand) in transit. **Benzoin Siam **comes in variable sizes of pebble- like, often tear-shaped pieces, hard and brittle, rarely agglutinated. The individual pieces are yellow-orange or yellowish-brown, and a characteristic feature is the almost white or cream-colored fracture. The odor is pleasant, sweet-balsamic with a distinct note of vanillin. When chewed, **Siam**** ****Benzoin**** **becomes plastic. Its taste is aromatic but somewhat acrid-bitter and biting. There are several grades commercially available of **Benzoin Siam**. "Selected tears" or "tears No. 1" are considered superior for perfumery purposes. Lower grades of "tears" are somewhat darker, and they may have more insoluble matter. "Almonds" or "Amygdaloid" forms of Siam Benzoin give a very pale tincture or extract, but these grades are less aromatic than "selected tears". The best grades of Siam **Benzoin **contain 95% or even more alcohol-soluble matter. (See monograph on **Benzoin Resinoid **and **Tincture**).