62 ETHEREAL OILS, TERPENES 



as of flowers, is due to the presence of so-called volatile or ethereal 

 oils, which are composed of mixtures of hydrocarbons (i.e. 

 compounds containing carbon and hydrogen only), known as 

 terpenes, and of their oxygen derivatives. Examples are : 

 lavender oil from the flowers of the Lavender (Lavendula) ; 

 peppermint oil, which contains the antiseptic menthol, from the 

 Peppermint (Mentha piperita) ; bergamot oil, used in the manu- 



FIG. 26. Photograph of part of the shoot, including two fruits, of the 

 Thornapple (Datura stramonium), which contains the alkaloids atro- 

 pine and hyoscyamine. [Photo E. J. S.] 



facture of Eau de Cologne and other perfumes, from the 

 Bergamot Orange (Citrus aurantium var. bergamia), a variety of 

 the ordinary Orange ; oil of aniseed from the Aniseed (Pimpinella 

 anisum) ; and the numerous oils from the many species of Euca- 

 lyptus (Myrtaceae). Many of these are used commercially in the 

 preparation of perfumes. Similar oils are the essential principles 

 of such spices as Cloves (the flower-buds of Eugenia caryophyllata) 



