216 REPORT— 1873. 



lional distillation, and their optical properties were determined by Dr. 

 Gladstone ; their corrected boiling-points were accurately detei-mined ; com- 

 bustions were made of them ; and the products of their oxidation by chromic 

 acid were carefully studied. Other cymenes from the undermentioned sources 

 were also submitted to the same treatment, 



A. Cymene from Myristicol by the action of Zinc Chloride. — When myristicol 

 is treated with solid zinc chloride in a small retort, a powerful action takes 

 place before the boiling-point is reached, water and cymene distil over, and 

 a non-volatile resinous mass is left in the retort. This resinous mass appears 

 to be formed by the reaction 



2n(C,AeO)=nH,0 + (C,„H3„0)„. 



After purification by shaking up with sulphuric acid and distillation over 

 sodium, the distillate yields tolerably pure cymene. 



B. From Myristicol by the action of Phosphorus PentncMoride.- — As stated 

 in last year's Report, myristicol, when treated with phosphorus pentachloride, 

 undergoes the reaction 



PCL + C,„H,,0 = POCI3 + HCl -h C,„H,,C1 ; 



the resulting body, Cj^H^jCl, breaks up on heating into hydrochloric acid and 

 tolerably pure cymene. 



C. From Camphor by Phosphorus Pentachloride. — Louguinine and Lippmann 

 have shown that the chlorinated body, Cj^H^jCl, obtained by Gerhardt and by 

 Pfaundler by the action of phosphorus pentachloride on camphor, breaks up 

 readily on continued distillation, forming hydrochloric acid and apparently 

 pure cymene ; their experiments were repeated, and their results confirmed in 

 every respect. 



D. Cymene from Hydrocarbons of Nutmey-oil (preexisting). — As stated in 

 last year's Eeport (Appendix), by treating the lowest-boiling fraction (163°- 

 ] 64°) of nutmeg hydrocarbon with strong sulphuric acid, the terpene is poly- 

 merized ; the resulting mass, when diluted with water and distilled, furnished 

 a crude cymene, which may be purified by repetition of the process and frac- 

 tional distillation over sodium. 



E. Cymene preexisting in Turpentine. — Turpentine-oil was distilled over 

 sodium, and found to boil at 156°-159°; on treatment with sulphuric acid 

 &c., about 3 per cent, of cymene was isolated. 



Recently Eiban has published some experiments almost identical in their 

 result with the foregoing observations (made in September and October 1872); 

 he, however, concludes that the cymene is derived from the terpene through 

 the oxidation of H^ by the sulphuric acid. The author dissents from this con- 

 clusion for various reasons, the two chief ones of which are that hesperidene 

 yields no cymene whatever by this treatment (although it does by bromine 

 and heat), and that cymene may be obtained from nutmeg hydrocarbons or 

 from oil of turpentine without evolution of sulphur dioxide, if very great care 

 be taken. 



Kekule, also, has recently obtained cymene from oil of turpentine by con- 

 tinued distillation along with iodine ; he considers that a diiodide is formed 

 and split up into hydriodic acid and cymene by the heat employed : this is by 

 no means improbable ; but it is not impossible that the iodine simjily poly- 

 merizes the terpene present, leaving the cymene originally present imaltered. 



P. Cymene from Cummin-oil. — Cummin-oil was distilled, a non-volatile 

 resin of empirical formula Cj^Hj^O being left in the retort ; the distillate was 

 shaken with sodium bisulphite and the uncombined cymene purified by treats 

 ment with sulphiiric acid and distillation over sodium. 



