The Chinese frequently adulterate the oil of cassia with colophony, which may be easily detected, as it has a greater specific gravity. Extra pale colophony has a specific gravity of 1.070 and the pale colophony has a specific gravity of 1.110. Any oil heavier than 1.070 should be handled with suspicion. The darker the sample and the higher the specific gravity, the greater the adulteration. The tips of the branches and the other trimming which collects are carefully dried and distilled and sold as cinnamon oil.
Oil of cinnamon or cassia depends entirely upon the amount of cinnamyl aldehyde it contains. Oil of the true cinnamon bark (cinnamomum Zeylonicum) is the finest essential oil to be had. It is worth $5 per pound, while common cassia is worth only about seventy cents. True cinnamon oil is obtained in Ceylon and is of a golden color when fresh, with an aromatic odor, and is very pungent, being powerful enough to blister the tongue, but varies by age from cherry to yellow-red, the paler varieties being the most esteemed. Cinnamon leaf is redistilled in London to obtain the desired color, although at a loss of about 10 per cent. (formula C10H14), with a small quantity of benzoic acid. Fine cinnamon oil has a taste of intense sweetness, far sweeter than sugar, and a clove-like taste is at first developed. It is largely used in perfumery and medicine. Ceylon ships about 15,000 to 40,000 ounces annually. China exports as much. After a time it loses its sweetness and is no better than cassia oil. The tree yields essential oils from the leaves, bark, and root, each oil differing in composition and value, which accounts for the many different grades or prices for cinnamon oil found on the market. Cinnamon and cassia oils are of the same chemical compositions, their value being estimated by the amount of cinnamyl aldehyde they contain. That obtained from the roots is light, while that obtained from the leaves is so heavy as to sink in water.
There is but a small amount of oil in the bark, the yield being but 1 to 1.5 per cent.; six and one-half ounces of heavy oil and two and one-half ounces of light oil to eighty pounds of bark. It consists chiefly of cinnamyl aldehyde or the hydride of cinnamyl and a variable quantity of hydrocarbon. The oil derived from the coarser bark is a dark-brownish color. The oil distilled from the true bark is worth about eighteen times as much as the oil distilled from the leaves or leaf stalk or flower stalk. The latter oil is chiefly of eugenol, a hydrocarbon having an odor of cymene, a little benzoic acid and cinnamyl aldehyde. When mixed with the young twigs and cassia buds of cassia shrubs, this oil becomes a beautiful bright oil of excellent taste—characteristics which denote a higher percentage of aldehyde. Twigs show a familiar sweet cinnamon taste, but they yield a smaller percentage of essential oil than is distilled from the leaves, and has a specific gravity of 1.45 at 15 degrees C., showing 90 per cent. of aldehyde. The leaves yield sweet oil at 15 degrees C., specific gravity 1.056, aldehyde 93. Cassia buds yield essential oil 1.550 per cent., specific gravity 1.026, aldehyde 80.4 per cent. Stalk of cassia leaves, leaf stalk, and young twigs mixed yield essential oil 0.77 per cent., gravity 1.055, aldehyde 93 per cent.
The oil from the root contains cinnamyl aldehyde, hydrocarbon and ordinary camphor, and is lighter than water, both the oil of the bark and of the leaves being heavier. Oil from cinnamon bark and shoots is seldom exported. The oil is obtained in Ceylon by macerating the powdered bark or roots with a saturated solution of common salt for two days, after which the whole is distilled.
Cinnamyl aldehyde, which is a very pleasant smelling colorless liquid, may be separated from hydrocarbon, which is also found in the oil, by bringing the oil in contact with concentrated nitric acid. The crystals, which separate in long rhombic prisms or small plates, are decomposed by water into nitric acid. Free cinnamyl aldehyde may be prepared by allowing a mixture of ten parts benzolaldehyde, fifteen parts acetaldehyde, 900 parts of water, and ten parts of a 10 per cent. solution of caustic soda to stand eight or ten days, at a temperature of 30 degrees, the whole being frequently agitated. Finally the aldehyde is extracted by means of ether.
The pure Chinese cassia lignea bark, essential oil 1.5 per cent., has a specific gravity of about 1.035 to 1.060; aldehyde, 89.9 per cent., and at 15 C. should have a specific gravity of 1.050 to 1.070. On distilling, about 90 per cent. of pure cassia oil should pass over, and the balance, 10 per cent. residue, must not become solid in cooling, must not be brittle but must be in a semifluid state. If the oil contains less than 70 per cent. of cinnamyl aldehydes it may be considered adulterated, and at 75 per cent. should be handled with suspicion.
| 14 to 9 years old, | 79 per cent. Cinnamyl aldehyde |
| 15 years old, | 70 per cent. Cinnamyl aldehyde |
| 16 years old, | 73 per cent. Cinnamyl aldehyde |
Cinnamic acid occurs in the flowers of cinnamon and forms in small quantities by oxidation of the cinnamyl aldehyde when it comes in contact with the open air. It will dissolve in 3,500 parts of water at 17 degrees and is more readily soluble in boiling water and crystallizes from it in lustrous plates. From the cassia buds, refuse bark, young shoots and roots a fragrant volatile substance is obtained which floats on water, and when removed and allowed to cool, it becomes a suet, giving a delicious odor in burning, called a cinnamon suet, or wax, which is used largely by the Catholics and Buddhists in worship and at high native weddings. It was formerly used in Ceylon for making candles.
When true ground cinnamon and cassias are examined microscopically with polarized light, differences are revealed at once which are characteristic enough to distinguish the specimens, as shown in [Figs. 41 and 23], Chap. III. But of the proximate chemical composition of any of the barks but little is known. Numerous determinations and analyses of the ash have been made with a view to detecting peculiarities or the addition of mineral matter. The percentage of ash is extremely variable, depending on the age and quality of the bark. Saigon chips have been known to have 8.23 per cent., while unknown cassia bark has been found with but 1.75 per cent. Cinnamon bark will be likely to average less than cassia. Fiber-like ash is very variable, Saigon yielding 26.29 per cent., true cinnamon 33.08 per cent., while unknown cassia gives 14.20; that containing the least fiber contains the smallest amount of lime.
The albuminoids are also variable; the Batavia and Saigon barks appear to contain the most. The presence of over 4 per cent. is an indication of an inferior quality.