Oleum Cassiae. Oil of Cassia.
Synonym.—Oil of Chinese Cinnamon.
Oil of cassia is obtained by distillation from Cinnamomum Cassia, Blume (N.O. Laurineae), cultivated in Southern China. It is official in the U.S.P. as Oleum Cinnamomi. It occurs as a mobile, yellowish or brownish, strongly refractive liquid, having an odour and taste resembling those of oil of cinnamon, but the odour is less fragrant and more pungent, and the taste—sweetish, spicy, and burning—is harsher than that of the cinnamon oil. It is optically inactive, or has only a slight rotatory power either to the right or left. The alcoholic solution is slightly acid to litmus. Specific gravity, 1.055 to 1.070 (1.045 to 1.065 at 25°). Boiling-point from 240° to 260°, with partial decomposition. On exposure to the air the oil becomes darker in colour and thicker. On cooling the oil to 0°, and then shaking it with an equal volume of nitric acid, a crystalline mass is formed (this serves as an identification test). Two decimils (0.2 milliliters) of the oil, dissolved in 10 mils of alcohol, should produce a brown, but not a green or blue, colouration, on the addition of a drop of ferric chloride solution (absence of oil of cloves or carbolic acid). Resin is frequently added and may be detected by the formation of a precipitate on adding a solution of lead acetate in alcohol (70 per cent.) to a solution of 1 mil of the oil in 3 mils of alcohol (70 per cent.).
Soluble in 2 parts of alcohol (80 per cent.); it generally yields a clear solution with 3 parts of alcohol (70 per cent.); soluble in its own weight of glacial acetic acid or of alcohol.
Constituents.—This oil is almost identical in composition with oil of cinnamon, but it is richer in cinnamic aldehyde, of which it may contain 75 to 90 per cent. (U.S.P., not less than 75 per cent. by volume). It also contains cinnamic acid, cinnamyl acetate, and a terpene. The free cinnamic acid, which is present to the extent of about 1 per cent., has the property of dissolving lead, which it may take up from the lead canisters in which the oil is shipped, and hence should be tested for lead by shaking with solution of hydrogen sulphide, when it should not assume a dark colour. Cinnamic aldehyde, when shaken with a saturated solution of sodium bisulphite, forms a crystalline mass of an addition compound, and the reaction is made use of for its assay as follows:—5 mils of the oil is shaken in a flask with a long, narrow, graduated neck (Hirschsohn or cassia flask), with 10 mils of a 30 per cent. solution of sodium bisulphite, and heated on a water-bath until the contents are liquefied; successive portions of the bisulphite solution are then added, shaking well after each addition, until the flask is three-fourths full. The heating is continued until the odour of cinnamic aldehyde disappears, the solution cooled, and sufficient bisulphite solution added to bring the lower layer of the supernatant oily liquid to zero mark on the graduated neck of the flask. This layer should measure not more than 1.25 mils, indicating at least 75 per cent. of cinnamic aldehyde. The specific gravity of cinnamic aldehyde and the other constituents of the oil being almost the same, differences in the aldehydic content are not apparent in the specific gravity.
Action and Uses.—Oil of cassia has properties resembling those of oil of cinnamon. It is employed as a flavouring agent and in place of true cinnamon oil.
Dose.—¼ to 2 decimils (0.025 to 0.2 milliliters) (½ to 3 minims).
- Aqua Cinnamomi, U.S.P.—CINNAMON WATER, U.S.P.
- Oil of cassia, 0.2; purified tale, 1.5; distilled water, to 100. Average dose.—16 mils (4 fluid drachms).
- Spiritus Cinnamomi, U.S.P.—SPIRIT OF CINNAMON, U.S.P.
- Oil of cassia, 10; alcohol (95 per cent.), 90. Average dose.—2 mils (30 minims).