| Benzoin is a balsamic resin. Normally the trees do not produce it or any
substance analogous to it, but the infliction of a wound sufficiently severe
to injure the cambium results in the formation of numerous oleoresin ducts in
which the secretion is produced, it is, therefore, a pathological product. The
trunk of the tree is hacked with an axe, and after a time the liquid Benzoin
either accumulates beneath the bark or exudes from the incisions. When it has
sufficiently hardened it is collected and exported, either in the form of
loose pieces (tears) or in masses packed in oblong boxes or in tins; several
varieties are known, but Siam and Sumatra Benzoins are the most important. The
incisions are made when the tree is seven years old, and in Sumatra each tree
yields about 3 lb. annually for ten or twelve years. The first three years'
collections give the finest Benzoin; after that the runnings are known as the
'belly,' and finally the tree is cut down and the resin scraped out, this
being termed the 'foot.' Siam Benzoin externally is reddish yellow, internally
milky white, has an agreeable odour, recalling vanilla, contains benzoic acid
but not cinnamic acid. Sumatra Benzoin is always in blocks of a dull reddish
or greyish-brown colour. Fine qualities have a strong storax-like odour, quite
distinct from the vanilla odour of the Siamese variety. Sumatra Benzoin
contains cinnamic acid.
The chief constituent of Siam Benzoin is benzoic acid (up to 38 per cent.),
partly free and partly combined with benzoresinol and siaresinotannol; it also
contains vanillin and an oily aromatic liquid. When quite pure it should be
entirely soluble in alcohol and yield only traces of ash. Sumatra benzoin
contains 18 per cent. or more of benzoic acid and about 20 per cent. of
cinnamic acid the latter partly free and partly combined with benzoresinol and
sumarisinotannol; it also contains 1 per cent. of vanillin, styrol, styracin,
phenyl-prophyl cinnamate and benzaldehyde, all of which combine to produce its
characteristic odour.
Medicinal Action and Uses. It is used externally in the form of a tincture,
diluted with water as a mild stimulant and antiseptic in irritable conditions
of the skin. It acts as a carminative when taken internally is rapidly
absorbed, and mildly expectorant diuretic and antiseptic to the urinary
passages. In the form of Compound Tincture of Benzoin, it is used as an
inhalant with steam in laryngitis and bronchitis. It is a preservative of
fats, and is used for that purpose in Adips Benzoatus. |
