VOLATILE OILS AND RESINS 79 



from the leaves of a certain kind of palm tree in Brazil by 

 scraping the surface of the leaves, melting and collecting it 

 in boiling water. It is an ester of so-called myricyl alcohol, 

 C30H61OH and cerotic acid, (VJI51COOII and some other 

 similar esters. It is used in making candles, polishing pastes, 

 and phonograph cylinders. 



71. Lecithin. — While this compound is not a wax or fat, 

 it is allied to them in chemical composition. It is an ester 

 of glycerine and choline with a fatty acid and phosphoric- 

 acid. Its formula may be as follows: 



H 



I 

 H— C— O— O— C . H 35 Ci7 



I 

 H— C— O— O— C . HsiCu 

 O 



H— C— O— P— O.CH2.CH2.N • (CH 3 ) 3 



I I I 



H OH OH 



This would be called a stearo-palmito-phosphate of glycerine 

 and choline. Other fatty acids may replace the two given. 

 It is a yellowish-white, waxy substance, soluble in alco- 

 hol, and other organic solvents. In water it forms an 

 opalescent emulsion or solution. Since it contains certain 

 fat radicles, a reduced nitrogen group, and phosphoric acid, 

 it may be useful in the formation of fats or of proteins. It 

 is found in cereal grains, peas, and beans, to a larger extent 

 than in other plants, although present in most plant cells. 



m. VOLATILE OILS AND RESINS 



72. General Definition. — The name oil signifies a liquid 

 having certain characteristic properties as noted in Section 

 63, but the volatile oils, also called essential or ethereal oils, 

 are less greasy in character than the fixed oils, and are 

 volatile on exposure to the air; so that the spot they leave 

 on paper will disappear in time. Chemically they are of 

 several different kinds of compounds, to be noted later 

 (Section 75). They are to be found free or as glucosides 



