98' Agricultural Chemistry. 



as choline. Lecithin is sometimes referred to as a " phosphorized 

 fat." It occurs in the seeds of cereals and to a gr3ater extent 

 in the seeds of legumes. 



Waxes have some properties in common with the fats and are 

 frequently associated with them in the plant and separated with 

 them by methods of extraction. They differ from fats in that 

 they contain an alcohol of higher weight in place of glycerine, 

 this alcohol being combined with the fatty acid in equal parts. 

 Chinese wax and the carnauba wax obtained from the leaves of 

 a South American palm are single compounds, while the waxes 

 found in the seeds of the palm, flax, cotton and other plants are 

 mixtures. The "bloom" of leaves and fruits, which serves as 

 a protective coating, is composed of waxes. These compounds 

 can be converted to soaps in the same manner as fats, but they 

 yield, of course, other alcohols in place of glycerine. 



Terpenes, essential oils, camphors and resins form another 

 group of closely related plant compounds. The terpenes belong 

 to a class of chemical compounds known as hydro-carbons, which 

 are composed of the elements carbon and hydrogen only. They 

 are partly liquids, such as spirits of turpentine, and partly solids, 

 such as rubber and gutta-percha. As in the case of carbohy- 

 drates, a classification of these bodies in order of complexity is 

 in use which separates them into mono-, di- and poly-terpenes. 

 Terpenes are products of pitch yielding trees. Turpentine is a 

 terpene of special value in the paint industry as a "thinner" 

 or solvent for fats and oils. 



The essential oils to which the characteristic odors of flowers 

 and flavors of fruits are due are partly hydro-carbons, as in the 

 case of oil of turpentine and oil of lavender. Others, such as oil 

 of wintergreen and almond oil, contain some oxygen. Heliotro- 

 pin of the heliotrope and the compounds to which the aroma of 

 the banana, orange and other fruits is due, are essential oils. The 

 pleasing smell of new mown hay is due to the essential oil, cou- 

 marin. These compounds are of value in the compounding of 

 perfumes, cordials and medicines. They are of special signific- 

 ance in foods because of their probable effect on palatability. 



