Aug. 2, 1897.] 
THE TROPICAL AGRICULTURIST. 
acid is destroyed. The plant can be easily moved from 
place to place. It does not pay to cart the trash 
far, but a few square miles of wattle country will 
keep a factory going. The utilisation of thinnings allows 
the cultivation of the tree thickly on waste ground, 
and to begin cutting the third year. European tan- 
ners are quite accustomed to the use of such extracts, 
but it is said that it will be very hard to introduce 
it into the colonial tranneries .” — (Chemist and Druggist, 
188'J.; . 
These words are still in succc-sful operation, al- 
though mucilage still gives some trouble. V/attle 
twigs are rich in gun and mu. :;age, and some cheap 
process, which will get rid of these substances and 
leave the tannic acid uninjured, is a desideratum. 
I have received many inquires as to whether the 
difficulty ha.s been overcome, but I have had to reply 
in the negative, as far as a commercial process is 
concerned. There is very little gum in clean-grown 
bark, but far more in chapped twigs; extract v/ill 
not be made from the former except in almost in- 
accessible districts. Of course, the extract in all 
stages of its manufacture must be preserved from 
contact with iron. Wooden vats are employed, and 
the heat for evaporation is obtained from hot water 
or steam. The waste bark, chips, &c., used in the 
preparation of the extract are first digested in cold 
water, and by having a serious of vats, with com- 
municating tubes or siphons, a charge of bark can 
be transferred from one to another it is ex- 
hausted to such an extent that the small remaining 
percentage of a tannic acid can only be removed by 
hot water. The vats are constructed so as to expose 
a maximum of evaporating surface to the atmosphere, 
and if the evaporation can be carried on wholly or 
in part by means of the heat of the sun, so much 
the better, firstly, because the consumption of fuel 
will be minimised, and secondly, because the pro- 
cess should be conducted at as low a temperature 
as convenient. 
The preparation of wattle bark extract has been 
attempted in all of the colonies, but in only one has 
it passed the experimental stage, so far as I know. 
The process is analogous to “ concentration ” in 
metallurgical operations, for the tannic acid in bulky, 
unsaleable material can be highly concentrated, and 
barks weak in tannic acid can be utilized for the 
same reason. The industry of eztract-making is 
tempting, and I am confident that there is much 
money in it for some of our country district whose 
circumstances are favourable. I trust, therefore, that 
it will soon be the means of affording profitable 
occupation to many people. 
The dark colour of extracts is an objection, and 
many experiments have been undertaken with the 
view to minimise the evil, with no very satisfactory 
results up to the present. Nothing is easier than 
to decolorise extract, but the difficulty is not to 
destroy the tannic acid at the same time. 
The following notes relating to the making of 
extract of hemlock bark are taken from Proctor’s 
“ Text-book of Tanning,” and may be suggestive 
“ The bark, in pieces |-1 in. thick and several inches 
long, is soaked for about fifteen minutes in water at 
200 deg. F. (93 deg. C.) ; it is then fed into a hop- 
per, which condricts it to a 3-roller machine, some- 
thing like a sugar-cane mill, through which it passes, 
coming out lacerated and compressed ; it next falls 
into a vat of hot water, where it is agitated by a 
wheel that the tannin from the crushed cells may 
be dissolved in the water ; hence it is raised by a 
series of buckets on an endless chain, somewhat in 
the manner of a, grain elevator to another hopper, 
whence it is fed to another 3-roller mill ; here it 
receives its final compression, and comes out in 
flakes or sheets, like coarse paper, and almost free 
from tannin. The buckets are made of coare wire 
that the water may drip through during elevation. 
In order to avoid the blackening action of iron, 
whenever this metal will come into contact with the 
solutions it is thickly coated n ith zinc. The solution 
is evaporated to a solid considteucy, generally by 
vacuum-pans. About 2 tons of bark are represented 
103 
by _1 barrel (of less than 300 lb.) of extract,” And 
again,—" It is one of the great attractions of ex- 
tracts that they avoid almost all the expense and 
labour inseparable from the exh lustion of other 
tanning materials. I is usually necessary to dissolve 
the fluid extracts in water or liquor of as high a 
temperature as has been employed in their pre- 
paration, as otherwise, from some unexplained 
chemical change, a large portion of the tannin is 
precipitated, probably as an anhydride of tannin.” 
It i.s of very little use, however, looking to the 
local demand for tanning material to take off 
more than a limited quantity of the Acacia de- 
currens bark or extract. It is the market in 
Europe that must he considered and last month’s 
London quotations for “ Australian cliopiied 
bark” (catalogued as Mimosa) was from £6 to 
£10 10s. per ton. ^Ve suppose this holds good 
as well for “ A. decurrens’’ hark, but we are 
unable to say how the extract sells, although, 
judging by the Australian trade, it must '’be 
satisfactory. Unfortunately, Mr. Maiden’s pam- 
])hlet was issued in 1891 and the statistics are 
only up to 1889. In that year, 21,625 tons 
of bark were exported from ail the Colonies 
t!ie value being entered at about £200,000. Nov.q 
in reference to Mr. Kellow’s pioposa! lliat a 
Company should be formed to take up land— a 
free grant (?) from Goveiniuent fora new industry 
—between Nanuoya and Ambawela, we must 
remember that the timber (as well as the 
bark) should be utilized, at least as firew'ood 
now in so much demand for tea factories in 
Dimbula. The return from firewood, perhaps, 
could not be put dowm at much ; but Mr. 
Maiden’s Estimate of Keceipts from a wattle 
Plantation of 100 acres (400 trees to the acre) 
for bark alone aggregates £4,852 for 1,215 tons 
of bark gathered between the 5th and 8tli years 
inclusive; while the total expenditure is given at 
£2,215, leaving a profit of £2,637. It may be 
said that these figures are not applicable to 
Ceylon, but it is very probable that with our 
cheaper labour and free land (if a grant were 
obtained) the outlay here w'ould be less. At 
any rate, for the present we may leave these 
facts and figures ’ for the consideration 
of any in our midst wlio are on the lookout 
for a new industry to no luomoted by a 
Limited Company or by individuals. 
It is rather interesting to note that of the three 
new industries now pressed on the attention 
of our Planting and Agricultural community, 
that in “ Wattles and Wattle Bark ” should 
be the only one suited for a high eleva- 
tion. The cultivation of “Rhea” and, in- 
deed, tliat of Para Rubber” are more parti- 
cularly adapted for the lowcountry or the 
lower valleys in our liill-country. We are, of 
course, aware that a good deal of Rubber has 
already been planted one way or another, and, 
no doubt, there are fields of Eliea in certaiii 
directions of which not much is said. It now 
lemains that a fair trial should be giv'en to 
W^SifctlGS Siiicl JJiirivs in tli6 direction 
recommended by Mr. Kellow under tlie guidance 
afforded in his valuable pamphlet by the scientific 
expert, Mr. Maiden of New South Wale.s. 
AGRICULTURE AND SCIENCE. 
Following on_ Mr. Green’s appointment we may 
take the following amiouncement (appearing in the 
Governimnt Gazette) to be a further step towards the 
goal of a fully constituted Agricultural-Scientific 
Board to work in the direct interests of the Euro- 
pean and Native planters and cultivators of all 
