QUEENSLAND NATIVE ASTRINGENT MEDICINES. 
30a 
gum benzoin. During the rain the gum softens and whitens, and has 
a remarkable appearance on the trees. When dry the colour again 
becomes brown. Cold water dissolves only a small amount of this 
gum, and the percentage of soluble tannates is not higher than 10, as 
already Grimwade has stated in the “ Pharmaceutical Journal,” 17th 
June, 1886. 
After long standing a watery solution of U. maculata gum makes 
a sediment of ellagic acid without any admixture of Eucalypto-arabin. 
An old watery solution reads as follows : — 
KOH makes a yellow colouration, turning blood-red inside, green 
outside (on an opal plate). 
Eerric acetate gives a beautiful blue colouration, 
Cupric acetate makes a light-brown precipitate ; cupric sulphate, 
a light precipitate, browner by addition of liq. ammon. 
Lime water makes a yellowish precipitate, turning purple-brown. 
Sulphide of sodium gives a deep yellow colouration ; lead nitrate 
makes a yellow precipitate; uran. acet. gives a red-brown mixture; 
and ammon. molybd. in nitric acid, a yellow-brown precipitate. 
Antimon. tartar, no change. 
A clear watery solution, boiled with dilute II Cl, makes a precipitate, 
which, on addition of alcohol, is partly dissolved. The soluble part — 
phlobaphene of eucalypto-tannic acid — is stained beautifully pink by 
addition of KOH. The grey insoluble part consists of ellagic acid,, 
and dissolves with intense yellow colouration in KHO. {Sometimes a 
fresh cold solution gives a sediment entirely dissolved in alcohol, and 
consisting of phlobaphene only, after boiling with hydrochloric acid. 
The soluble tannins are — (1) Ellago-tannic acid, always present in 
old solutions; (2) eucalypto-tannic acid, coming near to querci-tannic 
acid, as Grimwade already observed. 
The residue which is left in cold water dissolves partly in alcohol. 
A remnant of 25 per cent, of the whole gum is left undissolved. It 
consists of pure ellagic acid. The alcoholic solution consists now — (1) 
of two tannates ; (2) of a resin ; (3) benzoic acid ; (4) a very small 
amount of cinnamene derived from the benzoic acid, and not present 
in all gums. Of the tannates we have already spoken. The resin was 
thought by Mr. Staiger to be identical with sheliac, to which it bears 
some superficial resemblance, not being dissolved in benzene ; but it 
lias nothing to do with shellac at all. It softens very much in water, 
and really a part of it is dissolved and stained blue by ferric salts, and 
pink by KOH. It dissolves freely in ether, where the Alpha-and 
Beta-resin of shellac are quite insoluble. It dissolves in acetic ether,, 
which does not affect shellac. Finally it is dissolved by weak KOH 
solution, with deep yellow* colouration; and on neutralisation with an 
acid it gets stained blue-black by ferric salts. 
Moreover, if the solution of the resin is watched under the 
microscope only for a few minutes, crystals of glaucomelanate of 
potassium are seen separating quickly. All this shows plainly that in 
the resin of metadata we must recognise a resinous body derived 
from a tannate (tan resin) — uamely, from ellagi-tannic acid — as 
similar resins have been found by Schlagdenhauffen (“ Pharmaceutical 
Journal,” 1892, page 4, and 1893, page 5). 
