436 ON GRASS-TREE GUM, 



the moutli, but crunches readily, tinging the saliva yellow, and 

 tasting of benzoic acid to a far greater extent than X. arhorea. 



In boiling water the resin melts, the water becoming slightly 

 turbid and of a lightish yellow colour. 



Petroleum spirit extracts 1 per cent, of a fragrant body, but 

 apparently containing no benzoic acid. 



Alcohol digested on the residue dissolves 94'6 per cent., forming 

 a beautiful yellow liquid. As evaporation proceeds, benzoic acid 

 in beautiful feathery crystals separates out, and the resin collects 

 at the bottom of the vessel, the whole smelling strongly of benzoic 

 acid. This resin melts at 97 "7° C. Beyond applying the usual 

 tests for that substance,* nothing further was done in regard to 

 it, for lack of time. 



The accidental impurity was 5*3 per cent, (vegetable debris and 

 sand). 



A second sample purchased in Sydney is in small pieces 

 admixed with a little ligneous matter. The description already 

 given of this resin will apply here, except that it has a lower 

 melting point, the heat of a Sydney summer fusing it and causing 

 it to run together in the bottles. It is very strongly and deli- 

 ciously aromatic. Petroleum spirit extracts 2 per cent, of a pale- 

 coloured sticky substance, which is probably a mixture of essential 

 oil and resin. 



A third sample from Shoalhaven, N.S. W., collected 14th August, 

 1886, was then examined. 



Petroleum spirit dissolves out 2 per cent. The general effect of 

 cold alcohol and subsequent slow evaporation is the same in this 

 sample as in that already described. The alcohol dissolves out 

 91 '7 per cent, of resin and benzoic acid combined. 



The residue (accidental impurity) amounts to 8-1 per cent. 



* Stenhouse obtained a quantity of cinnamic acid, in far greater abundance 

 than the benzoic acid, from a sample of X. hastilis resin examined by him. 

 But, although I carefully examined the groups of crystals obtained, with 

 regard to physical appearance, and also mixed both them and samples of 

 the original resin with binoxide of manganese and sulphuric acid, I failed 

 to obtain indications of cinnamic acid. I hope some time, however, to give 

 the resin a more thorough examination. 



