SCIENCE AND INDUSTRY. 
Tannins fom Wattle Bark. 
Results of Investigations in New South Wales. 
The leather industry is one of the most important secondary industries in 
Australia, and there is little doubt that it will become even more important when 
tanning is placed on a more scientific basis, One essential is the supply of tan 
bark. For many years the bark used in Australian tanneries has been obtained 
mainly from two species of wattle—the golden wattle (Acacia pycnantha) of 
South Australia, and the black or green wattle (Acacia decurrens) and its varic- 
ties. As a fesult of the gradual destruction of wattle trees the Australian supply 
has become inadequate, and has been largely supplemented by wattle bark im- 
ported from Natal, where plantations haye been formed by the utilization of 
Australian seed. In addition to the wattles, a valuable tan bark is yielded by 
the mallet (Hucalyptus occidentalis) of Western Australia, but though the useful 
properties of this bark were only discovered in 1903, its exploitation was so 
rapid that only comparatively small quantities now remain. 
It is obviously a matter of great importance to insure a local supply of tannin 
for the future, and four possible means of doing this have been suggested, viz.:— 
(a) Regulation of bark collecting to prevent the destruction of young 
~ trees—Regulations on this matter are in existence in most of the 
States, but are difficult to enforce owing to the large areas and the 
small staff of the Forestry Departments. 
(b) Plantation of wattles for the production of bark.—Many such planta- 
: tions were established over 30 years ago, when estimates of prospec- 
tive returns were published which made the industry look attractive. 
but experience has shown that owing to the slow growth of the trees 
and the danger from bush fires, wattle plantations are not generally 
successful in Australia from the industrial point of view. 
(c) Discovery of new sources of tannin.—The Institute has collected infor- 
mation as to analyses of barks of Australian trees. The barks of 
about 150 species have been analyzed as to their tannin content, and 
15 of them been found to average over 20 per cent. of tannin. Of 
these, nine are wattles; but except for the two species already men- 
tioned, they are not-very abundant. ‘Two are Cypress pines, and one 
of these (Callitris calearata) is a plentiful tree in the eastern parts 
of Australia, and is utilized to some extent. Three are mangroves, 
but the bark from these trees has hitherto not been utilized to any 
extent in Australia, owing to the fact that it imparts an undesirable 
! red colour to the leather. -This problem is being investigated in 
i Queensland by the Institute, and a method of decolourization has 
been devised. The remaining species is the mallet referred to above. 
In addition, the kino (gum) produced by the redgum of Western 
Australia (Hucalyptus calophylla) contains a high percentage of 
tannin; but, as in the case of the mangrove, the leather tanned with 
this kino is stained a red colour. The redgum is very abundant 
in Western Australia, and has the peculiar advantage that the kino 
can be scraped off and collected without injuring the tree. The 
Institute is investigating the problem of its decolourization. 
(d) Manufacture of tannin extracts—This is another promising solution of 
the shortage of tanning materials, as it allows of the utilization of 
leaves, twigs, &c., as well as of barks containing too little tannin 
to be used directly. It would avoid the great amount of waste 
involved in the present methods of collecting wattle bark, in which 
the tree is cut down and the bark stripped from the trunk whilst the 
smaller branches and twigs are not utilized. Extracts have been 
prepared from wattle twigs, &¢c., by several Australian firms, but 
one of the difficulties is that gums and dyes are also extracted in the 
process, and the extracts have to be decolourized, whilst the presence 
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