896 ESSENTIAL OILS. 



leuca leucadendron of the Moluccas. In the crude state it is 

 green, but becomes colourless by rectification. 



Oil of caraways, extracted from the seeds of the Carum carui, 

 contains two different oils, one of which is probably a hydro- 

 carbon (Voelkel). These are different from the oils of the Cu- 

 minum cymimum, although the two plants befbng to the same 

 family. 



Oil of cummin is extracted from the seeds of the Cumihum 

 cymimum. The Roman oil was found by M.M. Gerhardt and 

 Cahours* to consist of two oils. One of these oils they have 

 distinguished as cymene ; it is a hydrocarbon C 20 H 14 , and boils 

 at 329. The other contains oxygen, and appears to be the 

 hydruret of a compound radical like benzoyl, which may be 

 named cumyl. Cymene is separated by dropping the essence 

 into hydrate of potash in a state of fusion, the hydrocarbon 

 distils over, and the hydruret of cumyl is retained by the 

 alkali as cuminic acid. The known compounds of cumyl are as 

 follows : 



Hydruret of cumyl, or cuminol . C 20 H n O 2 

 Cuminic acid .... C 20 H n O 2 4-O 

 Chloride of cumyl or chloro- cumin ol C 20 H n O 2 + Cl 

 Bromide of cumyl or bromo-cuminol C 20 H U O 2 + Br 

 Hydrated cuminic acid . . C 20 H n O 2 + O + HO. 



Hydruret of cumyl or -cuminol is a colourless or yellowish 

 liquid of a strong odour, easily altered by the contact of oxygen 

 when heated. Its boiling point is 428 ; density of its vapour 

 by experiment 5240, by calculation 5094, its combining mea- 

 sure being supposed four volumes. Cuminol is capable of 

 uniting with hydrate of potash at the ordinary temperature 

 without the evolution of hydrogen. It is oxidated and con- 

 verted into cuminic acid by direct oxidation, or when treated 

 with caustic alkali in which case hydrogen is evolved, or by the 

 action of sulphuric acid and chromate of potash. This acid, 

 which corresponds with benzoic acid, is colourless, crystallizes 



* Recherchea chimiques sur les huiles essentielles. An. de Chim. 3me Srie> 

 t. i. p. 60. 



