18 Mr. Noad on the Action of Nitric Acid on Cymol. 

 Preparation of Cymol. 



The experiments of Gerhardt and Cahours have shown that 

 cumin oil {oleum cmnini) is a mixture of two distinct oils, — 

 cuminol (C^oHigOj), a body corresponding closely to oil of 

 bitter almonds, and cymol (Coq H14) ; by treatment with 

 potash, the oxygen oil is converted into cuminic acid, while the 

 carbo-hydrogen distils over unaltered. As, for the experi- 

 ments about to be detailed, it was the latter of these two oils 

 that was required, the mode of separation which I found it 

 most convenient to adopt was the following : — The oil was 

 first submitted to distillation alone, and about two-thirds of 

 it drawn over ; this portion was then repeatedly distilled with 

 sticks of caustic potash, until the alkali remained unaltered ; 

 fresh potash was introduced after every third or fourth di- 

 stillation, and the oil was regarded as pure when it ceased to 

 lose anything after two or three distillations ; latterly I found 

 it advantageous to employ a retort of copper in this operation, 

 the heated alkali proving exceedingly destructive to vessels of 

 glass. The quantity of cymol obtained averaged about 7 oz. 

 for every pound of cumin oil; and here I must be allowed to 

 express my thanks to my friend Mr. Warington for having 

 kindly undertaken to furnish me with a supply of oil obtained 

 directly from the seeds by distillation : without his assistance 

 I should scarcely have been able to have followed out my in- 

 vestigation, on account of the high price and varying quality 

 of the oil obtained in commerce ; from three-quarters of a 

 hundred weight of seed Mr. Warington obtained at four di- 

 stillations 2 lbs. 12 oz. of oil, which yielded me 18 oz. of beau- 

 tiful and pure cymol. 



To render cymol perfectly anhydrous, it was left for some 

 time in contact with pieces of fused chloride of calcium and 

 again distilled; in this state it is a limpid, colourless, highly 

 refracting oil, of a very agreeable odour ; its specific gravity 

 I found to be 0'S576 at 16°, and its boihng-point, as a mean 

 of two determinations with two specimens of the oil obtained 

 at different periods, and which agreed closely with each other, 

 l7l°-5 C. 



Cymol has been identified with camphogene, a substance 

 previously obtained by Dumas*, by the action of anhydrous 

 phosphoric acid on camjihor, and lately studied by Dela- 

 landef. At the commencement of my experiments I thought 

 that this might probably be a useful practical method of pro- 

 curing the carbo-hydrogen ; from the difficulty however of 

 obtaining anhydrous phosphoric acid in sufficient quantities, 



* Liebig's Jnnalen, vi. 249. f ll^id. xxxviii. 343. 



