Oil of Ylang-Ylang (Oleum Unonæ odoratissimæ)
is imported from Manilla. It is colorless or yellowish, and has a most delightful characteristic odor, which is rather fugitive if not made resistant by other substances. It forms an important constituent of several of the most favorite and expensive essences.
Oil of Hyssop (Oleum Hyssopi)
is colorless, but rapidly becomes yellow in the air. It is used in some very cheap perfumes and in the manufacture of liqueurs.
Oils of Cinnamon (Oleum Cinnamomi).
Commercially we find chiefly three varieties of essential oils which are designated as: oil of Ceylon cinnamon, oil of Chinese cinnamon or oil of cassia, and oil of cinnamon leaves. Oil of Ceylon cinnamon, sometimes called “true oil of cinnamon,” made from the bark of the twigs of the cinnamon laurel and formerly imported mainly from Ceylon but now distilled in large amounts in Germany from imported cinnamon “chips,” is rather viscid, golden yellow to reddish-brown in color, of a burning though sweet taste. In the air it gradually absorbs oxygen, when it becomes dark red, thicker, and of weaker flavor. Oil of Ceylon cinnamon, which should always be used in perfumes or liqueurs when simply “oil of cinnamon” is directed, has a specific gravity of 1·030 to 1·035 at 15° C. (59° F.) and boils at about 240° C. (464° F.). Its chief constituent upon which its aroma depends is cinnamyl aldehyde.
Oil of Chinese cinnamon, or oil of cassia, has for a very long time, up to within a few years, always reached the market in a more or less adulterated state, a regular practice of the Chinese exporters being to dissolve ordinary resin in it (claiming afterward that the “resin” was caused by the oxidation of the oil through age) and often also to add petroleum to it. These frauds have been well shown up by Schimmel & Co., of Leipsic; and in consequence thereof, the quality of oil of cassia exported from China has been greatly improved. Oil of cassia when pure has a specific gravity of 1·060 to 1·065, and should contain not less than seventy-five per cent of cinnamyl aldehyde.
Oil of cinnamon leaves is an inferior product, often used for adulterating oil of Ceylon cinnamon. It does not deserve notice by the perfumer.
As an appendix we may add in this connection a description of the