November i, iS8g.] THE TROPICAL 
AGRICULTURIST. 
313 
BLACK WATTLE BARK AND OTHER 
TAN BARKS. 
On this subject we have received the following 
interesting letter :— 
To the Editor " Ceylon Observer." 
The Technological Museum, Sydney, 
August 3rd, 1389. 
Dear Sib,— With reference to the correspon- 
dence on the subject in the July issue of the 
Tropical Agriculturist, I beg to give you the 
following information, having made a speci- 
alty of Australian tan-barks during the last few 
years. 
In the first place, a word as to botanical and 
local nomenclature : — Acacia decurrens Willd. is the 
principal species called " Black Wattle "; it also 
goes by the name of " Green Wattle.'' The variety 
mollis (not mollissima), has been properly restored 
to specific raok, and is now as formerly A. mollis- 
sima Willd. Its commonest names are "Black" 
and " Silver Wattle." 
With reference to memo, by " J. D. V." the 
timber of neither species is thought much of 
here ; it is occasionally used for staves and 
only occasionally for fuel, eucalyptus timber 
being our great wood-fuel. In Australia the wood 
of acacias is exceedingly liable to attacks by the 
larvte of certain lepidoptera,* and ofcen for miles 
it is difficult to get a sound log. 
In regard to Mr. Tringham's letter, 34-35 per 
cent of tannic acid is excellent, and the 40 per 
oent quoted lower down and also 47 per cent for 
A. pycnahtha probably refer to extractive, and not 
to tannic acid. I challenge any man to produce 
a sample of either bark, which will give such 
results with a standard process such as Lowenthal's. 
There is frequently much quackery in so-called 
tan-analyses, and some flagrant instances of 
bogus analyses have come under my notice at the 
Museum. The analyses in the report of the Victo- 
rian Wattle Bark Commission, from which all the 
information on the subject in Spon is derived, refer 
only to extracts and not to tannic acid, a distinc- 
tion with a very important difference. 
Ere this letter reaches you, you will have 
received through Messrs. Trubner & Co. a 
copy of my " Useful Native Plants of Aus- 
tralia," which gives the fullest information 
upon our tan-barks yet published. All the 
analyses there given are of barks from trees 
botauically determined for the purpose. Since the 
work was published I have read part V. of " Some 
New South Wales Tan Substances " before the 
Royal Society of New South Wales (a copy of which I 
beg to send you), and there record the percentage 
of tannic acid in A. decurrens bark at 36-297 per 
cent, the highest I have ever come across in all 
my experience. 
Mr. Tringham mentions that from A. decurrens 
he gets a soluble office gum. This is not our ex- 
perience in Australia, as the gum of A. decurrens 
is all but insoluble in water, simply forming a 
jelly in that liquid. I send a specimen of botani- 
cally correct Australian A. decurrens gum to 
illustrate my remarks.f If Mr. Tringham is not 
mistaken in his species, the occurrence of a 
soluble gum on this species in Ceylon is most 
remarkable ; and if he has any doubt, I hope he 
* Wo have not observed auy snch tendency iu Cey- 
lon and of course our correspondent did not mean to 
include that source of Hue timber, A. mclauoxylon, 
the " blackwood " of Australia.— Ed. 
t Not received.— Ed. 
•10 
will submit flowering and fruiting specimens to 
some competent botanist.* — Yours faithfully, 
J. H. MAIDEN, Curator and Secretary. 
Mr. Maiden is correct in supposing that, in 
addition to a series of valuable papers on 
objects in the Museum of which he is the 
very efficient Curator, sent to us from Sydney, 
we have received from the London pub- 
lishers a copy of his interesting work on the 
Useful Native Plants of Australia, which we value 
very highly and to which we shall frequently 
have to make reference as the qualities and pro- 
ducts of Australian trees are discussed, whether as 
yielders of timber, or foods, drugs, oils, gums, 
dyes, tans, fibres, &e. We strongly recommend this 
book, published by Triibner & Co., to readers inte- 
rested in the culture of Australian trees. At 
present, we turn to the information contained in 
the pamphlet forwarded with Mr. Maiden's letter, 
and we find the following details: — Lowenthal's 
process of analyses of tanning substances is fully 
described, and various tanning barks are noticed. 
First comes that of 
Cupania semiglauca, F. v. M., N. O. Sapindaeeaa, 
B. Fl., i., 457. 
Of this bai-k Mr. Maiden writes : — 
Externally this bark might perhaps be mistaken by 
an expert for Black Wattle bark (A. decurrens) . Cer- 
tainly it would require more than a casual observation 
to detect its substitution if admixed with Wattle bark 
in the bundles as ordinarily sent to market. 
But there are important differences, the character- 
istics of the bark of A. decurrens being thus 
stated : — 
1. May be considered perfectly smooth. 
2. Slight longitudinal flutes on the outside. 
3. The inside is usually nearly as smooth as dressed 
timber. 
4. Inside bark dark reddish brown. 
The results of analyses of the bark which resembles 
that of A. decurrens so closely are thus given : — 
Extract. — 28 62 per cent. Colour, rich orange brown 
slightly darker than that of Gallicoma serratifolia ; of 
moist residue, ochrey brown. 
Tannic acid. — 14-933 per cent. Non-tannin and im- 
purities — "914 per cent. 
Passing over a couple of acacias we come to A. sali 
cina, which gave 
Extract.— 35 28 per- cent. Colour, bright ruby ; of 
moist residue, dark pure brown. 
Tannic acid — 13-200 per cent. (The blacks are aware 
of the value of this tan-bark, as they use it for tanning 
wallaby and otner skins.) Non-tannin and impurities 
— 1-524 per cent. 
Next we have A. prominens with extract 39 - 98 
per cent and tannic acid 14-425. A. elata gave 
36-2 p. c. extract and 20-11 tannic acid. And 
now come the extraordinary results obtained from 
A. decurrens bark, from\a high tabic land : — 
Extract — 62 54 per cent. Colour, iich ruby ; of moist 
residue, very dark sienna-brown. 
Tannic acid — 36-297 per cent. Non-tannin and im- 
purities — 2'438 per cent. The percentage of tannic 
acid is extraordinary, and in order to avoid all possible 
error, the above is the mean of three separate analyses 
(not of three samples of the same liquor but of three 
separate liquors), which gave closely agreeing results. 
Mr. Thomas Shepherd, an enterprising tanner of 
Cambewarra, N. S. W., has kindly furnished me with 
* We hope that Mr. Tringham will act on this hint ; 
and if Mr. Maiden would kindly make up specimens 
of A. decurrens, A. pyenantha and A. dealbaia and 
send them to us by an officer of ore of the P. & O. 
steamers, wa shall feel much obliged, and we may 
thus be able to settle doubt as to the ideutity of 
some of the acacias naturalized in Ceylon. Some 
seeds of A, binervata would also be welcome, and 
we should gladly remit the cost, — Ed. 
