1879.] 



Examination of Essential Oils. 



291 



Cedrat hydrocarbon. 



Cubebs. 



Elder. 



Hesperidene, from oil of orange-peel. 



Indian G-eranium. 



Juniper. 



Lavender. 



Lign- Aloes. 



Melaleuca Ericifolia. 



Menthol, from oil of mint. 



Nutmeg hydrocarbon. 



Patchouli, oil of, Nos. 1 and 2. 



Bose, otto of. 



Eosewood. 



Eosemary. 



Santal wood. 



Terebene. 



Terebenthene. 



Vitivert. 



Hydrocarbons showing the absorption bands of cymene. 



Thyme. Nutmeg. 



Lemon. Carraway (No. 1). 



Substances showing strong bands of absorption in the spectrum transmitted 

 by dilute solutions. 



Oils of Aniseed. Carrol, oxidised derivative of carraway oil.. 



Bay. Myristicol, the same from nutmeg oil. 



,, Eergamot. Patchouli, blue oil of. 



Bitter Almonds. Oils of Peppermint. 

 Cassia. „ Pimento. 



Cloves. „ Thyme. 



For the most part these latter substances are known to contain the 

 aromatic nucleus as an essential part of their constitution. Thus the 

 oils of bay, pimento, and cloves, contain the substance eugenol, or 

 C 6 H 3 .OH.OCH 3 .C 3 H 5 ; oil of cassia consists of cinnamic aldehyde, 

 C 6 H 5 .C 2 H 2 .COH; oil of aniseed of anethol, C 6 H 4 .OCH 3 .C 3 H 5 ; and 

 oil of thyme contains thymol, C 6 H 3 .OH.CH 3 .C 3 H 7 , as well as much 

 cymene, C 6 H 4 .CH 3 .C 3 H 7 . 



Some other oils, such as bergamot and oil of peppermint, as likewise 

 the bodies menthol, carvol, and myristicol, have an unknown con- 

 stitution. Tbe three latter substances are known to be isomeric 

 (" Journal of the Chemical Society," vol. xxv, p. 1). 



Great interest is attached to our examination of these bodies, since 

 we consider it to be proved from the character of the spectra they 

 transmit that the nucleus of menthol is a terpene, while the benzene 

 ring is the inner basis of carvol and myristicol. Bergamot appears to 

 be a terpene mixed with some derivative of the aromatic series, but the 

 oil of peppermint on the other hand is essentially a substance belonging 

 to this latter class. The refraction equivalents of carvol and myris- 

 ticol are abnormal, like those of benzene derivatives, a fact which 

 confirms our conclusions regarding the constitution of these sub- 

 stances. 



The following is a summary of our observations with regard to the 

 terpenes : — 



1. The terpenes with the composition C 10 H 16 possess, in a high 



