1 1 1 



on rectification 80 per cent, came over below igo. This fraction appeared to 

 consist very largely of cineol, suggesting an increase of cineol in the oil during 

 the nineteen years it had been kept. The crude oil and the large fraction gave 

 the following results : 



Crude oil, sp. gr. at 15 . = 0-9690; rotation + 4-8; refractive index 



at 20 = 1-470. 

 Large fraction ,, ,, =0-9290; rotation a D + 3-4; refractive index 



at 20 = 1-4610. 



The cineol was determined by the resorcinol method in the portion 

 distilling below 190; when calculated for the crude oil, the result was 76 per 

 cent. By the rapid phosphoric acid method it was 58 per cent, when calculated 

 for the crude oil. 



56. Eucalyptus rOStrata, var. borealis. 



(R.T.B. & H.G.S., in Euc. and their Ess. Oils, ist Edit., 1902.) 

 River Red Gum. 



Systematic. It has long been known by stockmen that cattle will eat the 

 leaves of only one kind of " River Gum " (E. rostrata, Schl.), but which kind 

 it does not seem possible to differentiate in the herbarium. Morphologically, 

 no variations could be detected between the Murray River specimens and those 

 received from Broken Hill and Nyngan, but they differed, however, in chemical 

 constituents, and this probably partly accounts for this choice of trees by stock. 

 After our experience with E. apiculata, we have little doubt but that morphological 

 differences do exist between these two Eucalypts, and will yet be found, so that 

 a systematic description can be given for each species. On chemical grounds, 

 we have decided to separate the Northern " River Gum " from the Southern 

 "River Gum" under the varietal name of borealis. 



For the data in reference to the type E. rostrata, see under that species. 



ESSENTIAL OIL. Leaves and terminal branchlets for distillation were 

 obtained from Nyngan, New South Wales, in December, 1899. The yield of 

 oil was 0-8 per cent. Pinene was found, but phellandrene was quite absent. 

 Constituents having a high-boiling point were present only in small amount. 



The oil of this tree is rich in cineol, and the leaves might be distilled 

 commercially, but oil could not be profitably extracted from the leaves of the 

 type E. rostrata. 



The crude oil had specific gravity at 15 C. == 0-9109 ; rotation a D + 5-46; 

 refractive index at 20 - 1-4654, and was soluble in if volumes 70 per cent, 

 alcohol. The saponification number for the esters and free acid was 4-8. 



On rectification 2 per cent, distilled below 170 C. (corr.). Between 170-183, 

 85 per cent, distilled; between 183-250, 5 per cent, distilled. 



The specific gravity of the first fraction at 15 C. = 0-909, of the second 

 fraction = 0-9142. The rotation of the first fraction a D + 6-37. 



The cineol determined by the phosphoric acid method in the first fraction 

 was 52 per cent. . (O.M.), indicating about 45 per cent in the crude oil. 



