Decembkr, 1912. 



KNOW 



;i)(^.i- 



widely distributed coinpoiiiuls 

 found in the essential oils, and 

 form the subject of extended 

 scientific research. The hydro- 

 carbons possess the general 

 molecular formula C,,, Hj,;. and 

 are often accompanied in nature 

 by other unsaturated ones of 

 higher molecular weight, having 

 the same empirical formula, 

 C,, Hg. Those expressed by 

 C-io H04 have been named 

 sesquiter[)enes, whilst the more 

 comple.x ones still have been termed polyterpenes 

 (C,-,Hg)„. Although the constitution of the terpenes 

 has not been definitely ascertained, they are known 

 to be derivatives of benzene, and the accompanying 

 formulae are those generally accepted as expressing 

 the relations of the hydrocarbon camphene, the 

 alcohol borneol, and the ketone camphor to hexa- 

 hydrocymene, the hexahydrogen derivative of 

 methylisopropyl benzene. 



(2) Although many naturally occurring alcohols 

 (e.g., borneol, terpineol, and so on) in essential oils are 

 derivatives of the terpenes, it is convenient to 

 mention them separately. They are usually asso- 

 ciated in Nature with their esters (compounds of 

 the alcohols with acids — in this case, of the fatty 

 series) ; for instance, linalol (C,q Hjg O) is accom- 

 panied by linalyl acetate (Cjo Hj, O-COCH,,) in 

 lavender oil, and geraniol (Cm Hjg O) by geranyl 



Table 50. 



