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IX. On the Composition of certain Essential Oils. By Robert Kane, M.D., 

 M.R.I. A., Professor of Natural Philosophy to the Royal Dublin Society 

 and of Chemistry to the Apothecaries' Hall of Ireland, Corresponding 

 Member of the Society of Pharmacy and of the Society of Medical Che- 

 mistry of Paris, Honorary Member of the Society of Apothecaries of the 

 North of Germany, ^c. 



Read 12th June, 1837. 



1 HE analyses, which constitute the material of this paper, were undertaken as 

 the first step in a train of research, which had for its object the solution of two 

 problems in organic chemistry, the importance of which will be at once recog- 

 nized ; namely, first, whether there exists a law connecting the composition of 

 the oils derived from the same natural family of plants ? and secondly, what is 

 the chemical nature of the essential oils as a class ? is the oil of bitter almonds a 

 type for all ? Towards a decision of these questions some materials have been 

 collected ; but the investigation embraces a field so wide, that considerable time 

 must elapse, before even such general results, as have been already obtained, can 

 be worked into a form fit for publication. In the meantime I am induced to 

 lay before chemists those conclusions with respect to the composition of some of 

 the oils, which may serve as data in a solution of the first question, and as 

 initiatory to the more abstract considerations on their composition as a class. 



I. COMPOSITION OF OIL OF ROSEMARY. 



The oil of rosemary, obtained in its purest commercial form, is colourless, 

 and possesses strongly the odour of the fresh plant. Its specific gravity is given 

 by Brande 0.9118. 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, 



VOL. xviii. u 



