246 ODOROGRAPHIA. 



alcoholic solution is cautiously oxidised with permanganate of 

 potash, furnish the most reliable chemical tests for cineoL* 



An elaborate investigation of the physical properties of 

 eucalyptol was made in 1892 by Davies and Pearmain, and read at 

 a meeting of the British Pharmaceutical Conference at Edinburgh, 

 23rd Aug., 1892. The eucalyptol examined was prepared in a 

 state of great purity by " the freezing-out process " : The 

 temperature produced by a mixture of two parts of snow with 

 one of salt was — 20-5^ C. (= — 5^ P.), and working in the open air 

 (February), the atmospheric temperature being at the freezing 

 point or a few degrees below, " it was easy to keep quantities of 

 between one and two lbs. at or just below — 18^ C. (zero P.) for an 

 hour or more." (A lower temperature is obtainable by using 

 snow than crushed ice, owing to its finer state of division.) 



At this low temperature it was found that without any previous 

 fractionation, three samples of oil gave abundance of crystals. 

 These samples were the oils of " Eucnhjphis oleosa " so-called, (now 

 known as the product of E. cneorifolia, D.C.), E. dumosa, and one 

 stated by the importers as from E. globulus. After allowing time 

 for crystallisation, the whole was transferred to a small hand-press 

 capable of holding a quart, which was previously cooled, and 

 after the oil had drained off, the crystals were submitted to 

 strong pressure, a firm white cake of eucalyptol being obtained. 

 This was subsequently mixed with a similar product from two 

 further supplies of oil, and the whole re-frozen and pressed twice. 

 This constituted the bulk of the eucalyptol obtained. Some of 

 it was very carefully distilled, using a " Bell Henninger's " 

 fractionating tube, and it was found that on this distillation, out 

 of 75 c. c. taken, 69 c. c. distilled at 174°-o C. Of this 69 c.c, on 

 redistillation, 67 c.c. distilled at 175^0 by another thermometer; 

 and on this 67 c. c. being again distilled, it entirely came over 

 between 174^ and 175°, using a third thermometer. The boiling 

 point of eucalyptol may therefore 1)e assumed to be 174°-5 

 (uncorrected). 



The thrice distilled product was examined as to action on 

 polarised light, using a column of 220 m. m. The rotation, 

 judging from three closely concordant observations, was — 10'-7 

 from which the rotation of 100 m. m., would be — 4'-8. The 



* British and Colonial Druggist, xxii., p. 534. 



