TJR'GANTC COMPOUNDS OF PXANTS 2C9 



to the aromatic series of compounds (see Section 138). 

 According to chemical composition, they may be divided 

 into four groups, and each group in turn into a number 

 of subdivisions. 



Groups. Examples. 



1. Terpenes, C^H^.. Oil of lemon, oil of turpentine, 



2. Cedrenes, C 15 H 24 Oil of cedar, oil of cubeb. 



3. Aromatic aldehydes. . . 'Oil of cinnamon, oil of almond. 



4. Etherical salts ... Pineapple and fruit flavors. 



The essential oils are separated from plants by distil- 

 lation. At ordinary temperatures, most of them are 

 liquids, insoluble in water, but soluble in alcohol. When 

 the terpenes and cedreties oxidize, they produce resinous 

 deposits from which turpentine is obtained (see Section 

 135). The aromatic aldehydes form a homologous series 

 beginning with benzoic aldehyde, C 6 H 5 .CHO, and are 

 present in many plants and fruits, imparting flavor. 

 Ethyl formate, C 2 H 5 .HCO 2 , peach flavor, ethyl butyrate, 

 C 2 H 5 .C 4 H 7 O 2 , pineapple flavor, and amyl valerate found 

 in apples, are some of the common etherical salts. 



284. Essential Oils of Agricultural Crops.^-When 

 hay is cut, the odor produced is due to a volatile oil. 

 This material is lost when the hay is overcured or ex- 

 posed to leaching rains. The characteristic odor of 

 clover, particularly pronounced in sweet clover, is due 

 to an aromatic body. The odors of all fodder crops are 

 imparted by characteristic essential oils. In the prepa- 

 ration of hay and fodder crops, it should be the aim to 

 prevent, as far as possible, any loss of essential oils. 

 This can be accomplished by cutting the fodder before it 



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