438 Dr. Kane on the Composition of certain Essentiil Oils. 



fresh plant Its specific gravity is given by Brande 0*9 11 8. 

 I found the oil of commerce to be 0*897 ; but like all these 

 oils it differs according to seasons, from the variable quantity 

 of stearopten it may hold dissolved. When submitted to 

 rectification it distils over, the boiling point rising, but not 

 rapidly ; and the last portion in the retort becomes brown, 

 and of a thick consistence. By repeated distillations it can 

 be rendered completely pure. 



Its specific gravity is then from 0*8854< toO'8875.' Berzelius 

 states the specific gravity of the pure oil to be 0"889. It boils 

 at a temperature from 332° to 334° Fahr. Its boiling point is 

 almost absolutely constant, — indeed much more constant than 

 that of any other oil I have examined. It was analysed in 

 the ordinary way by combustion with oxide of copper, and 

 the carbonic acid collected, by potash, in Liebig's apparatus. 



A. Material = 0*300 gramme, gave 



Water = 0-315 



Carbonic acid = 0*907 



B. Material = 0*247 gramme, gave 



Water = 0*261 



Carbonic acid = 0*744 

 Hence follows 



A. B. 



Carbon = 83*49 83*31 



Hydrogen = 11-66 11*66 



Oxygen = 4*85 5*03 



These analyses, having been made with quantities of oil 

 distilled at different times, and coinciding so completely, ren- 

 dered it unnecessary to increase the number. 



The above result is fully expressed by the formula C45 Hgg 



330*3 100-00 



Evidently C45 Hgg O^ = 9 (C5 H4) + 2 HO; that is, we 

 may consider oil of rosemary as a hydrate of one of those 

 numerous oils, agreeing in per cent, composition with oil of 

 turpentine. This relation induced me to make some experi- 

 ments on the action of various bodies on it, the results of 

 which belong properly to a future memoir, but of which I 

 shall transcribe one here. 



When mixed with sulphuric acid, oil of rosemary becomes 

 black, and neutralized by lime gives a soluble salt, which 

 contains an acid belonging to the class composed of oxygen, 



