and lo c.c. of the ether gave 0-026 gram of a soft aromatic resin =1-62 per cent. 

 A determination with alcohol gave tlie following result:— Two grams of the 

 air-dried gum, dissolved in water, were precipitated by excess of alcohol ; the 

 clear filtrate was evaporated to drvness, treated with ether to remove a small 

 amount of gum, and the ether evaporated. The amount of soft resin thus 

 obtained was 0^044 gram, equal to 22 per-cent. of oleo-resin. One might thus 

 suppose that the manganese in the exudation of A . Cunninghamii was utilised 

 more largely in the formation of the resins. When the air-dried exudation was 

 ignited it gave 2-02 per cent, of a perfectly white ash, wliich consisted almost 

 entirely of the carbonates of lime and magnesia: — CaCO, =49-7 per cent, 

 MgCO; = 49-9 per cent., ^In..= ooig per cent. 



The moisture in the air-dried material was 15-12 per cent, and this was 

 almost entirelv taken up again on standing in the air. 



The mucic acid was determined in the usual way, and 2 grams of air-dried 

 material gave 0-351 gram mucic acid = 17-55 per cent. This is a little less than 

 was obtained with the gum of .4. Cunninghamii. 



The gum after treatment with ether was quite insoluble e^•en in l^oiling 

 water, and ga\-e a bright vellow colour with iodine. 



There was an absence of reducing sugars in this exudation, ard Fehling's 

 solution was not reduced. 



For the determination of the sugar formed by hydrolysis, the gum was 

 boiled for some hours with a dilute solution of sulphuric acid. The acid was 

 remo\'ed by bariinn carbonate, the filtrate evaporated down, and the unaltered 

 gum removed by alcohol. On evaporation, a syrup was obtained which eventually 

 became somewhat crystalline. The sugar formed was dextrorotatory, and it 

 strongly reduced Fehling's solution. The indications, howe\'er, for either arabinose 

 or xylose were not convincing, and its identity remains in abeyance. 



It is, perhaps, remarkable that a soluble gum giving mucic acid on 

 oxidation, should be rendered insoluble and changed into a jelly by the simple 

 agitation with ether. The reaction is of interest and worthy of further study. 

 On keeping the gum of A. Bidwilli for many years, it did not entirely lose this 

 property, although it became modified somewhat, and less distinctive. No jelly 

 of an insoluble nature could be obtained witli the gum of A . Cunninghamii by 

 this reaction, thus indicating a different molecular arrangement of the carbo 

 hydrates in the two trees. 



