142 Dr. Kane on the Composition of certain Essential Oils. 



royal has the same composition as camphor, and as the new substance described 

 by me in the memoir on Acetone, and which I have termed Dumasine* A 

 very interesting problem, which I hope soon to be able to solve, will be, to 

 determine the relative changes which dumasine and oil of pennyroyal undergo, 

 in the circumstances under which common camphor yields camphoric acid. 



Oil of pennyroyal is more frequently adulterated with oil of turpentine, and 

 to a greater extent, than any other oil that I know of. I have found specimens^ 

 which delivered four-fifths of their volume of pure oil of turpentine on rectification. 

 Thus, in the commencement of these experiments, I isolated and analyzed 

 quantities of the product of rectification of commercial oil of penny-royal, and 

 stated verbally at a meeting of the Academy, that I could not find any difference 

 between rectified oil of pennyroyal and oil of turpentine. I shall detail a couple 

 of the analyses, made under those circumstances, because the result may be used 

 as a test for the closeness of the other experimental results, and for the legitimacy 

 of the formula deduced from them. 



Fluid obtained by rectifying impure oil of pennyroyal, specific gravity = 

 0.8673 ; boils constant at 315°. 



A. Material = 0.2183 gramme gave 



Water = 0.232 



Carbonic acid ^ 0.697 



B. Material =: 0.2433 gramme gave 



Water = 0.260 



Carbonic acid = 0.779 

 Hence 



A. B. Theory. 



Carbon = 88.29 88.56 88.45 



Hydrogen = 11.78 11.87 11.55 



Its formula c^ H4. It was oil of turpentine. 



* It had been my intention to insert the account of the composition and properties of Dumasine 

 as an appendix to the memoir on Pyroacetic Spirit, but it has been withheld in order, when further 

 studied, to form the subject of an independent paper. A notice of its discovery and composition 

 was pubhshed in the Proceedings of the Royal Irish Academy, No. IV. page 61, and copied from 

 thence into the Philosophical Magazine for 1837, 



