234 A TEXT-BOOK OF BOTANY. 



in the oils of valerian and serpentaria, the acetate of this alcohol 

 being found in many oils of the Pinaceae. 



ALDEHYDES. The simplest of the aliphatic aldehydes, for- 

 maldehyde, has been found in apopin oil, the latter being derived 

 from an unknown plant growing in Japan. Acetaldehyde is com- 

 monly present in the distillates of seeds. Citral is found in 

 lemon oil, giving it its characteristic odor. It is also found in the 

 oils distilled from the leaves and twigs of the lemon tree, sweet 

 orange tree, sassafras, etc. Benzaldehyde is formed upon the 

 hydrolysis of amygdalin. 



KETONES. Of the aliphatic ketones, acetone has been ob- 

 served, together with hydrocyanic acid, in the distillation of a 

 number of leaf oils. Carvone occurs in the oil of caraway^ 

 Pulegone occurs in large amounts in European pennyroyal 

 oil and the oils of other members of the Labiatae. Japanese or 

 laurel camphor is obtained by the distillation of the wood of 

 Cinnamomum Camphora. Irone, a cyclic ketone, occurs in orris 

 root. 



PHENOLS AND PHENOL ETHERS are found in a number of 

 volatile oils. Thymol constitutes the larger part of the oil of 

 ajowan (Ptychotis coptica). Carvacol is a constituent in many 

 Labiate oils. Anethol is the principal constituent of the oils 

 of Pimpinella Anisum and Illicium verum and is an important 

 constituent in the oil of fennel. Eugenol occurs in the oils 

 of the Myrtacea and Lauracecc. Apiol is a constituent of the 

 fruit of parsley, and safrol is the principal constituent of 

 sassafras oil. 



ACIDS. Quite a number of acids are obtained as a by-product 

 in the aqueous distillation of volatile oils. Among these may be 

 mentioned formic acid, acetic acid, isovaleric acid, benzoic acid, 

 cinnamic acid, salicylic acid, etc. 



ESTERS give the fragrance to most volatile oils. Some oils 

 consist almost entirely of esters, as wintergreen oil and birch 

 oil, which contain methyl salicylate. The latter is probably one 

 of the most widely distributed of the esters. Linalyl acetate is 

 the characteristic constituent of bergamot and lavender oils. 

 Geranyl acetate is found in the oils of lemon grass, neroli, 



