44-8 Dr* Kane on the Composition of certain Essential Oils. 



up into other bodies with which we can get more definite re- 

 sults; and 3rd, their combinations with other bodies have 

 not been as yet developed. Towards the application of these 

 methods I have made some progress in the cases of oils of 

 rosemary, lavender, and oil of turpentine, which all give with 

 sulphuric acid and a base, soluble salts, of which that from 

 turpentine alone has been completely analysed. The atomic 

 weight of turpentine from the salt of lime is found to be 

 C20 Hjg; the same as from artificial camphor; and the salt 

 has the composition SO3 . CaO . + CggHjg, belonging to a 

 series distinct from the sulpho-vinates on the one hand, and 

 the sulpho-naphthalates upon the other, and being probably an 

 analogue to the sulpho-mesitylic acid described in my memoir 

 upon Acetone. I mention these results, although they pro- 

 perly belong to a different paper, in order to point out the 

 probable means of applying the methods of control to the 

 essential oils in future investigations. I attempted very often 

 to determine the densities of the vapours of the essential oils 

 with a bath of chloride of zinc, but I never obtained a result 

 on which I could with satisfaction rely. The residual oil was 

 evidently altered in its nature and appearance, and there al- 

 ways remained in the globe a certain quantity of permanent 

 gas. I attribute the imperfect success of these attempts, to 

 the mutual action of the oil and air of the globe at the high 

 temperature necessary for the experiment ; but by a modifi- 

 cation of the apparatus I may possibly at a future period suc- 

 ceed. 



A circumstance connected with the purification of the oils 

 employed in the analyses detailed in this paper requires some 

 notice here, as it has not been adverted to under the special 

 heads ; namely, the means used to secure the perfect freedom 

 of the oils from water. This is the more important, as parti- 

 cularly in the results obtained with the oils of marjoram and 

 spearmint, the small quantity of oxygen might be conceived 

 as being derivable from this source, unless proper precaution 

 had been taken. The oils, previous to rectification, were in 

 all cases digested for several days on recently fused chloride 

 of calcium; then poured off, and distilled; and the portions 

 selected for analysis allowed to remain in contact for about 

 twelve hours with a few pure fragments of chloride of calcium, 

 before being used. In no case did the oil appear to act on, 

 or dissolve any of the fused salt ; and hence it was only ne- 

 cessary to pour the oil off from the chloride, and not to again 

 distil it, in order to obtain it pure. 



