Oil of Pennyroyal. 44,3 



These analyses give the formula Cjo Hg O, or 

 Carbon = 61-4 79-30 



Hydrogen = 8-0 10-35 



Oxygen = 8-0 10-35 



77*4 100-00 



This result is exceedingly remarkable, as from it follows 

 that oil of pennyroyal 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 in- 

 teresting 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 analysed quantities of the product of rectification of com- 

 merqial oil of pennyroyal, and stated verbally at a meeting 

 of the [Royal Irish] Academy, that I could not find any dif- 

 ference between rectified oil of pennyroyal and oil of turpen- 

 tine. 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 formulae deduced from them. 



Fluid obtained by rectifying impure oil of pennyroyal, spe- 

 cific 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 



Its formula C5 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 com- 

 position was published in the Proceedings of the Royal Irish Academy, 

 No. IV. page 61, and copied from thence into the Philosophical Magazine 

 for 1838. (Load, and Ed. PhU. Mag. vol. xii. p. 108.) 



