82 PLANT COMPOUNDS 



76. Some Common Volatile Oils. — (a) Oil of Bitter 

 Almonds. — This oil is benzaldehyde, CeHsCHO, occurring in 

 the almond kernel as a glucoside of hydrocyanic acid and ben- 

 zaldehyde, called amygdalin. The fixed oil is first expressed, 

 and the cake is crushed, soaked in water until the enzyme, 

 emulsin, hydrolyzes the glucoside to benzaldehyde, hydro- 

 cyanic acid, and dextrose. The mixture is then distilled. 

 Hydrocyanic acid is a very powerful poison and care must 

 be taken in the distillation. Moreover, the distillate must 

 be carefully freed from hydrocyanic acid before use. Apricot 

 and peach seeds also contain amygdalin and most of the 

 commercial oil of bitter almonds is obtained from the former. 

 It is a white liquid when pure, heavier than water, and is 

 used in making dyes and for flavoring purposes. 



(b) Oil of Cinnamon. — This oil consists mostly of 



cinnamic aldehyde and eugenol, represented below, 

 /\ CH 2 .CH:CH 2 



\ CH:CH.CHO 



\/ \ / 



O.CH3 



OH 



with some other compounds. It is obtained by distillation 

 from the bark of the cinnamon tree, and is a yellow oil, 

 heavier than water, and is used in flavoring, for perfumes, 

 and in pharmacy. 



(c) Oil of Cloves. — This oil is practically all eugenol 

 with a little sesquiterpene. It is obtained from the dried, 

 unopened flower buds of the clove tree, growing in the East 

 and West Indies. It is a yellow oil, heavier than water, and 

 is used in pharmacy, perfumery, and for flavoring. 



(d) Oil of Lemon. — This is mostly a terpene, limonene, 

 C10H16, with less than 10 per cent, of citral, 



CH3\ 



>C:CH.CH 2 .CH 2 .C:CH.CHO 

 CH 3 / I 



CH S 



