120 AURANTIACEiE. 



the ^C'lielle a inqiier are mobile liquids of a faint yellow colour, of ex- 

 quisite fragrance and bitterish aromatic taste. 



The different specimens which we have examined are readily mis- 

 cible with bisulphide of carbon, but dissolve sparingly in spirit of wine 

 (0"830). An equal weight of the oil and of spirit of wine forms a 

 turbid mixture. No peculiar coloration is produced by mixture with 

 perchloride of iron. 



The oils are dextrogjTe, but differ in their rotatory power, as may be 

 illustrated by the following results, which we obtained by examin- 

 ing them in a column 50 millimetres long in the polaristrobometer of 

 Wild. The oil of Signori Panuccio, due to the sponge-process (p. 

 118, note 2), deviated 20*9°, that of Monsieur Medecin {Essence de 

 Citron au zeste) obtained by the 4cuelle a piquer deviated 83"4'' and 

 his distilled oil 28-3°. 



Chemical Composition — The prevailing portion of most essential 

 oils of the AurantiacecG agrees with the formula C^^ff® ; the differ- 

 ences which they exhibit chiefly concern their optical properties, 

 odour, and colour. The boiling point mostly varies from about 170° 

 to 180° C, the sp. gr. between 0'83 and 0'88. These oils are a 

 mixture of isomeric hydrocarbons, and also contain a small amount 

 of cymene, C^^'H", and of oxygenated oils, not yet well known ; 

 of these we may infer the presence either from analytical results 

 or simply from the fact that the crude oils are altered by metallic 

 sodium. If they are purified by repeated rectification over that 

 metal, they are finally no longer altered by it. Oils thus purified 

 cease to possess their original fragrance, and often resemble oil of 

 turpentine, with which they agree in composition and general 

 chemical behaviour. 



As to essential oil of lemons, its chief constituent is the terpene, C^"H^®, 

 which, like oil of turpentine, easily yields crystals of terpin, C'ff^SOH". 

 There is further present, according to Tilden (1879) another hydro- 

 carbon, C^°H^®, which already boils at 160° C, whereas the foregoing 

 boils at 176° 0. Lastly a small amount of cymene and of a compound 

 acetic ether, C^H?'0(C^"ff"0), would appear to occur also in oil of 

 lemons. The crude oil of lemons already yields the crystalline com- 

 pound C^H^*' 4- 2HC1, when saturated with anhydrous hydrochloric gas, 

 whereas by the same treatment oil of turpentine affords the solid com- 

 pound C"Hi6 + HCl. 



Essential oil of lemons (not the distilled) when long kept deposits 

 a greasy mass, from which we have obtained small crystals apparently 

 of Bergaptene (p. 123). 



Commerce — Essence of lemons is shipped chiefly from Messina 

 and Palermo, packed in copper bottles called in Italian rcmiiere and by 

 English druggists "jars," holding 25 to 50 kilo, or more ; sometimes in 

 tin bottles of smaller size. The quantity of essences of lemon, orange 

 and bergamot exported from Sicily in 1871 was 368,800 lb., valued at 

 £144,520, of which about two-thirds were shipped to England.^ In 



their establishment at Reggio. We have ^ Consul Dennis, On the Covimerce, <kc. of 



also had a small quantity prepared by the Sicily in 1869, 1870, 1871. (Reports from 



iciielle by one of ourselves near Mentone, H.M. Consuls. No. 4. 1873. 

 15th June 1872.— D. H. 



