VOLATILE OILS. 43 



It is characteristic of the oils of geranium, lemongrass, 

 citronella, lavender, sassafras leaf. 



Aromatic alcohols are few, but of practical interest. 

 Benzyl alcohol, as benzoates and cinnamates, is of im- 

 portance in the balsams of tolu and Peru. Other im- 

 portant members of this group are terpineol, borneol, 

 and menthol. The two latter are camphor-like bodies, 

 the former prevalent in Bomeol camphor, and in the 

 oils of spike, rosemary, sage, thyme, etc. ; menthol is 

 a characteristic ingredient of the peppermint oils. It- 

 is a saturated secondary alcohol, as follows: 



CH, CH, 



\ / 

 C— H 



I 

 C— H 



H.,C CHOH 



I I 

 H,C CH, 



CH 



I 



CH, 



Aldehydes are frequent and impart characteristic odors. 

 Citral, citronellal, benzaldehyde, and cinnamic aldehyde are 

 the most important. 



Ketones are few in number. Carvone, camphor, thu- 

 yone, and pulegone are ketones. Ordinary camphor, or 

 Japan camphor, C^^^fi, distinguished from Borneol 

 camphor, is the most important of this group. 



Within recent years a number of phenols have been 

 obtained from the volatile oils and prepared on a large 

 scale. The most important of these are thymol (C^HjCHj, 

 C3H7OH) (methyl propyl phenol), from thyme; car- 

 vacrol, from origanum oil; anethol, from anise; etigenol, 

 from the oil of cloves. Closely related to these phenols 

 is apiol, which is found in the oil of parsley. 



Of less frequent occurrence and yet of interest are 

 the nitrogen and sulphur compounds found in the mustard 



