AUSTRALIAN MELALEUCAS AND THEIR ESSENTIAL OILS. 373 



Melaleuca examined, and what might be expected, more 

 so in the channel of the midrib. Bundles occur through 

 the median line of the spongy parenchyma, the central 

 vascular bundle, — the midrib, of course, being the largest. 

 It is normally orientated and entirely surrounded by a thin 

 layer of sclerenchyma fibres. The medullary rays being 

 well defined, the cells increasing outwards in size. 



Essential Oil.— The oil of this species is another instance 

 of the differences in the characters and constituents of 

 those obtainable from the various species of Melaleuca, as 

 it has little resemblance to that of ordinary "cajuput." 

 There appears to be an entire absence of pinene in this oil, 

 the terpene present being limonene and probably dipentene. 

 The principal constituent is a high boiling one, and no less 

 than 67 per cent, of the total oil came over between 260 — 

 276° (corr.)» This high boiling fraction consisted principally 

 of a sesquiterpene, and as it occurs in the oil of this species 

 in such large quantity it should be possible to work out its 

 chemical characteristics and combinations, and so deter- 

 mine whether it is new to science. It is dextro-rotatory, 

 and the optical rotation of the purest sample so far obtained, 

 was Oro = + 8*5°. Its specific gravity is somewhat high 

 = 0*9364 at 15° 0., and its refractive index at 21° O. = 

 1*5004. It boils between 260 - 270° O. It has marked 

 colour reactions when two drops of oil are dissolved in 10 cc. 

 solvent, and shaken with one or two drops of sulphuric acid. 



(a) If the solvent is glacial acetic acid the colour is pink 

 at once, soon changing to crimson, and then to pur- 

 plish-brown on long standing. 



(o) If the solvent is acetic anhydride the colour is bright 

 green at once, soon becoming darker green, and deep 

 blue on long standing. 



(c) If the vapours of bromine are passed over a film of 

 the oil on a watch glass, the colour is bright blue 

 and violet at once, changing to green on standing. 



