This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
The dried bark of Acacia arabica, Willdenow, or of A. decurrens, Willdenow (N.O. Leguminosoe). Both of these species are large trees, the former indigenous to India, Arabia, and Africa, the latter to Australia. Both are largely cultivated for their bark which is much used in the tanning industries. The bark should be obtained from trees at least seven years old and be kept for one year before use.
Acacia arabica (babul bark) occurs in rather large pieces, hard and woody, rusty brown, readily dividing into several layers. Periderm thick, blackish, rugged, fissured longitudinally and transversely. Inner surface red, longitudinally striated and fibrous; taste astringent and mucilaginous.
Acacia decurrens occurs usually in curved or channelled pieces 1.5 to 3.0 mm. thick, externally greyish brown, becoming darker when kept, often with irregular longitudinal ridges and transverse cracks; inner surface reddish brown, longitudinally striated; fracture coarsely fibrous; freshly fractured surface pale.
Both barks contain tannin (about 22 per cent.) and gallic acid.
As an astringent.