Of the hard resins, benzoin alone is used in perfumery; of the balsams, Peru balsam, Tolu balsam, and storax balsam; and of the gum-resins, the myrrh.
_Benzoin_ is exclusively obtained from _Styrax benzoïn, Dryand_ (_Benzoïne officinale, Hayne_), a tree which grows in Java, Sumatra, and Siam. The bark of the tree is slit to allow a fluid to flow out, which concretes on the trunk in the form of grains, or is collected in vessels in which it congeals and assumes the form of lumps ("tampangs"). Older trees which have been frequently tapped for resin yield a product of a lower quality; the grains ("tears") forming, as a rule, the better varieties. When the benzoin collects in large masses it always shows an amygdaloid structure, the grains ("almonds") of a roundish form, smooth termination, homogeneous structure, and paler color, appearing imbedded in a dark, porous, or resiniform mass.
According to the appearance of the product three varieties are distinguished: Benzoin in tears (_B. in lacrimis_), _amygdaloid benzoin_ (_B. amygdaloides_), and lump benzoin (_B. in sortis_, _B. in massis_). The _benzoin in tears_ forms loose, smoothly terminated, longish, homogeneously appearing masses of an opal-like lustre, and first of a whitish, and later on, of a yellowish, reddish, or brownish color. The separate pieces are up to 3 millimeters in diameter, though the Siam benzoin in tears frequently consists of still larger and generally decidedly flattened pieces.
_Amygdaloid benzoin_ consists chiefly of white pieces, becoming, later on, brownish, of a waxy lustre and imbedded in a lustrous brown-red resinous mass. The _lump benzoin_ or _ordinary benzoin_ has also an amygdaloid structure but is not so rich in almonds as the preceding variety and possesses either a fine granular or colophony-like ground-mass and is frequently contaminated by parts of plants. The exterior of the variety occurring in commerce in large lumps shows, according to the mode of packing, the imprint of leaves or of coarse pack-cloth.
Benzoin generally consists of cinnamic and benzoic acids which occur in a crystalline state in the grains as well as the ground-mass; further, of several amorphous resins soluble in alcohol, and coloring matter. The content of cinnamic and benzoic acids amounts to from 12 to 20 per cent. The best varieties from Sumatra and Singapore contain no benzoic acid, and those from Siam no cinnamic acid.