PROSANTEHERA AND ITS ESSENTIAL OIL. 107 



thymol was obtained. The crude oil gave the following 

 results: — Specific gravity at 15° 0. = 0*9204. Refractive 

 index at 22° 0. = 1*4711. Soluble in 1*7 volumes 70 per 

 cent, alcohol (by weight). The colour of the oil was too 

 dark to allow the light to pass, and as phenols were present 

 the ester determinations and the rotation were made with 

 the oil from which these, and the aldehyde, had been 

 removed. This cleared oil had the following characters : — 

 Specific gravity at 15° C. = 0*9199. Rotation a D = +4°*1. 

 Refractive index at 22 3 = 1*4706. Saponification number 

 of ester + free acid = 9*9 by boiling, and 8*5 by cold 

 saponification with two hours contact. 



Esterised oil. — A quantity of the cleared oil was boiled 

 with acetic anhydride and anhydrous acetate of soda in the 

 usual way, separated, and washed until neutral. The oil 

 had altered little in appearance, but was more aromatic, 

 reminding one strongly of geranyl-acetate. The saponifica- 

 tion number of the esterised oil by boiling had increased to 

 34*2 and by cold saponification to 18*3. It is thus probable 

 that the principal ester in the oil of this plant is geranyl- 

 acetate, and that a portion of free geraniol is also present. 

 This was indicated by the marked odour of geranyl-acetate 

 in the esterised oil, the secondary odour of geraniol in the 

 saponified oil, and the results of cold saponification. It was 

 not feasible to separate the pure geraniol, as it was only 

 present in small amount, and the oil available was not 

 sufficient for the purpose, but we have now separated 

 geraniol from so many Australian essential oils in a pure 

 condition, (even from the pine-needle oils of the Oallitris), 

 that we have little doubt that the principal ester in this 

 Prostanthera oil is geranyl-acetate. The amount of this 

 ester in the esterised oil was equal to 6*4 per cent., and as 

 the whole ester formed was only 11*9 per cent., taking the 

 molecule as O 10 H 17 OH, more than half was geranyl- 



