440 ON GRASS-TREE GUM, 



It softens in boiling water, but does not appear to dissolve to 

 any extent. It almost entirely dissolves in rectified spirit, forming 

 a rich port wine-coloured liquid. 



Petroleum spirit digested on the resin extracts '3 per cent of a 

 yellowish resin destitute of odour. If the residue be digested in 

 alcohol, 94*2 per cent, is dissolved out. This consists almost 

 entirely of a deep orange-brown resin. An evaporation proceeds, 

 a few minute needles of benzoic acid are observed to crystallize 

 out, while the concentrated alcoholic liquid smells slightly of the 

 same substance. But in no instance was the benzoic acid in any- 

 thing like the comparative abundance in which it was obtained in 

 the case of X. hastilis. Therefore, when only these two resins are 

 in question, they may readily be distinguished (1) by their colour, 

 (2) by the difference in quantity of benzoic acid. 



The accidental impurity amounted to 5*5 per cent. 



Neither of this nor of any other Xanthorrhoia resins did time 

 permit me to make a qualitative examination of the resin ; nor 

 were the products of distillation inquired into. 



Sample from Oatley's Grant, George's River, near Sydney. 



Petroleum spii'it extracts "3 per cent. 



The effect of alcohol is the same as on the preceding sample. 

 It extracted 89*8 per cent. The residue (9'9 per cent.) consisted 

 of debris from the bases of the leaves, and no trace of free carbon 

 could be detected by means of a lens. This observation is inter- 

 esting in view of the statement I have made above (p. 430) to the 

 effect that the darkening of Xanthorrhea resin may be due to the 

 presence of carbon after bush-tires. This particular sample was 

 gathered by me from the midst of a freshly-extinguished bush-fire, 

 where everything was black and charred, and the resin, dug up 

 almost from the surface of the ground, was black likewise. The 

 resin is a little darker in tint than the other samples of X. arborea, 

 both before and after treatment with alcohol, an effect which seems 

 simply due to the heat alone, without admixture of carbon. 

 Numerous other samples will require to be collected and examined 

 before this point is settled. 



