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.
Cassia bark is obtained from Cinnamomum Cassia, Blume (N.O. Laurineoe), a medium-sized tree, probably a native of Cochin China, but cultivated now in the south-eastern provinces of the Chinese Empire (Kwang-si and Kwang-Tung). This tree yields the bark known in English commerce as cassia bark or Chinese cassia lignea. Other species of Cinnamomum growing in the country between these provinces of China and north-eastern India yield barks to which the name of Cassia vera (or sometimes also Cassia lignea) is given; they are exported from Calcutta and Saigon. The cassia vera of the London market is a firm, rather thick bark with a very mucilaginous taste; it is said to be the bark of C, Burmanni, de Candolle.
The bark is collected entirely from cultivated trees. When about six years old the branches are cut and all the small twigs and leaves are stripped off; two longitudinal slits are then made, and three or four transverse incisions are cut round the circumference through the bark at intervals of about 40 cm. The bark is then removed in pieces about 40 cm. long and half the circumference of the branch. These are next laid with the concave surface downwards and a small plane passed over them, by which the cork and part of the cortex are more or less completely removed. The bark is then tied up into bundles and exported in boxes resembling tea chests, which are sometimes wrapped in bast-mats.
Description - Cassia bark is imported in bundles about 30 or 40 cm. long and weighing about 500 grammes. The pieces of which the bundle is composed vary from 5 or 6 to 40 cm. in length and average from 1 to 2 cm. in width and 3 to 5 mm. in thickness. They are either channelled pieces or single (but not double) quills, of a dark, earthy brown colour and smooth, but with patches of the thin greyish cork still adhering to the outer surface, indicating a want of care in trimming them.
The fracture is short, the section of the thicker pieces showing a faint white line (sclerenchymatous cells) sometimes near the centre, sometimes near the outer margin and parallel to it. In odour and taste cassia bark resembles cinnamon, but it is less delicate in aroma and more mucilaginous and astringent.
Cassia bark occurs in much larger and thicker pieces than cinnamon, seldom in double quills, and never packed into sticks. It is darker in colour, and frequently exhibits patches of cork on the outer surface.
The student should observe
(a) The thickness of the bark and its dark colour,
(b) The patches of cork,
(c) The characteristic odour and taste.
The constituents of cassia bark are similar to those of cinnamon. It yields from 1 to 2 per cent. of volatile oil, resembling that of cinnamon but having a higher specific gravity (1.050 to 1.070) and containing more cinnamic aldehyde (75 per cent.) but no eugenol.