MrETLE. 67 



the length of the leaves. The pedicels bear t\yo linear bracteoles 

 under the flowers. The calyx is 5-cleft. The seeds are reniform. 

 The embryo is arched, with a long radicle, and small equal 

 cotyledons.* 



The essential oil of myrtle was first examined by Gladstone, 

 1867,t with the result that three-quarters of the specimen 

 operated on distilled over between 160^ and 176^ C, leaving 

 a reddish brown residue, which evolved sulphuretted hydrogen. 

 The rectified distillate proved to be a hydrocarbon of rather high 

 sp. gr., with an odour resembling that of the hydrocarbon from 

 Bay. Messrs. Schimmel record the sp. gr. to be 0"89 to 0*92 at 

 15^ C, and that it is composed of Pinene, Cineol and Dipentene. 

 Under the name of " niyrtol," an oil described as the portion 

 boiling between 160^ and 170*^ C. has been introduced into 

 commerce as preferable for medicinal purposes to the crude oil, 

 an assertion which induced Herr E. Jahns, of Gottino'en, to 

 investigate both the essential oil and this " myrtol," with a view 

 of ascertaining to which constituent the medicinal properties are 

 referable.:|: The sample of oil used, described as " Spanish," was 

 pale yellow, of sp. gr. 0-910 at 16° C, and strongly dextrorotatory. 

 This oil began to boil at 160° C, and about 80 per cent, distilled 

 between that point and 2-10° C. Upon fractionation there were 

 obtained : — 



lo_A turpene, C^^H^^, boiling at 158-160° C, corres- 

 ponding to a right-handed pinene. 



2"_Cineol, C.oH.^O, boiling at 176° C. 



3° — A very small quantity of a camphor, probably corres- 

 ponding to the formula Cj ^ H^ g O. 



Considering the compound nature of this " myrtol," it would be 

 better described as " rectified oil of myrtle." Herr Jahns is of 

 opinion that the reputed medicinal value of myrtle oil and myrtol 

 depends upon their strength in cineol, which body has been shown 

 to be identical with cajeputol and eucalyptol, and he suggests that 

 instead of such a mixture (dextrogyre pinene, cineol, and dipentene), 

 pure eucalyptol should be prescribed, or if the presence of terpene 

 is thought desirable, a mixture of eucalyptol with rectified 



* G.iertn. Fruct., i. p. 184, t. 38; Lam. 111. t. 410. 



+ Journ. Chem. Soc, xvii. 11. 



X Archiv. der Pharni., 1889, p. 174. 



