July 1, 1903. J THE TROPICAL AaRICULTURIST. 3 
Alders, birches, and willows in Northern Indiu are 
used, the willow being used in ilussia in conjnnction 
with Birch oil to form Russian leather. Of Conifers 
the Hemlock sprnce is considerably used in America, 
and produces a very strong reddish brown leather ; 
the Larch and Scotch Pine are used in limited 
quantities in Europe, two Pines and two Ephedras 
in Northern India. 
(2) Fruits. — Valonia is the acorucup of the 
Turkey oak which "is imported into Great Britain 
to the extent of some 30,000 tons. Myrabolans are 
the fruits of Terminalia, very abundant on the 
west coast and in the southern districts of Madras, 
but almost exterminated in other parts of the Presi- 
dency, as in former years the tree was cut to 
collect the traits. Some 34 lakhs of rupees worth 
an exported annually, chiefly from Bombay and 
mostly to Gsrmauy, as they contain from 31 to 44 
pet cent of tannin, and are one of the cheapest 
forms in ' which tannin can be bought, the principle 
being gallo-tannic acid ; they produce a yellowish 
green leather, which is both improved by, and improves 
the colour of. Oak, Hemlock and Babul (or wattle) 
barks. The best kind are the Chebulio myrabolan, 
which should be golden yellow in colour, pointed 
at both ends, and heavy, and should be collected 
just before they ripen. Another kind are Beleric 
myrabolans, whilst Emblic myrabolans belong to 
the Indian Gooseberry tree of a different family, 
e,nd when immature contain 35 per cent, but only 
traces of tannin when ripe. Divi divi is the twisted 
pod of a Csesalpinia, but is not much appreciated 
as the mucilage in the pod ferments easily, draws 
damp, causes rot, and in a dry atmosphere produces 
a dark horny leather. Two other species of Caasal- 
pinia. Babul and Wagaten produce somewhat better 
tan-pods. Other fruits producing tannin are : Man- 
gosteen, Mesua, Bael, Valeria, Jujube tree, Mango, 
Pomegranate. 
(3) Leaves. — The most important leaf-tan is 
Sumach, derived from species of Rhus belonging to 
the mango family, especially used for tanning light 
skins and making morocco leather, and containing 
ellagic and gallic aeids. Other similar leaves are : 
Pistacio, Mango, Tamarisk, Coriavia, Tamarind, 
Calycopteris, Indian almond, Careya, Guava, Wood- 
fordia, and Phyllanthns Emblica, the latter espe- 
cially is supposed to be an excellent substitute for 
Sumach. 
(4) Galls. — These are excrescences formed by 
insects on vegetable organs, usually containing some 
70 per cent of ellagic and gallic acid ; the principal 
are Aleppo galls on an oak, Chinese galls on a 
Rhus, but they are also found in abundance on 
many Indian trees, especially Tamarisk, Garuga, 
Pistacio, Acacias, Pongamia, Prosopis, Terminaliaa 
and other kinds. 
(5) Exti-acts.—lhe principal extracts are Cutch, 
Gambier and Kino. Catch and Gambler are both 
known in commerce as Terra Japonica, and are 
practically the same thing except that the former 
comes from the chips of Indian Acacias, the latter 
from the leaves of a Straits Settlements climber 
(TJncaria) of the coffee family, For cutch, trees of 
from 25 to 30 years of age with a diameter of 
12 inches are billetted into lengtha of 2 or 3 feet, 
the bark and sapwood removed, chipped into chips 
of about one inch square ; chatties holding 3 or 4 
gallons are filled as full as possible with these 
chips, and filled up with water, boiled for about 
12 hours till the water is reduced to half, the 
liquor poured into other chatties and boiled for 
about 4 hours, perpetually stirring to prevent burning, 
until it becomes the consistency of syrup, when it 
is taken otf the fire, allowed to cool, taken out and 
spread on leaves in a wooden frame, and left till 
the morning when it is dry enough to cut into 
pieces. About one ton of wood gives from 250 to 300 
pounds, the value being about 30 to 35 shillings per 
cwt. About 24 lakha of rupees worth are exported 
annually, chiefly from Burmah, but the trade ought 
to be greatly developed iu iUadras. It is used not 
so much as a tan in itself for leather, as for 
softening .'eather, and principally foe tanning fishing 
lines and canvas for trunks, etc.. Kino is the red 
juice of Pterocarpus, B /tea, Spatholobus, Ougeinia, 
Hardwickia, and other leguminous trees, and can 
also be obtained from Eucalyptus and some of the 
Blue-Plums ; it ia used for softening leather and 
also for medicine. 
♦ 
THE UTILITY OP ALKALINE PHOS- 
PHYTIC MANURES. 
By John Hughej, P.I.O. 
Before considering the subject included undtr the 
title of this paper, it will be desirable to briefly 
refer to the origin and progressive use of 
ACID PHOSPHATIC MANURES. 
The mannfaoture of superphosphate in this country 
may be said to have commenced in 1842, when the 
late Sir John Bennett Iiiwes, F R.S., obtained a 
patent for treating flnelyground mineral phosphates, 
such as Cambridge coprolites, with commercial 
sulphuric acid. The chemical theory then put forth 
maintained that the agricultural value of phosphatic 
manures depended upon the extent to which the 
phosphates they contained were rendered soluble in 
water through the aid of acid. It was contended 
that this solubility in water effected the most com- 
plete diffusion through the soil that could possibly 
be obtained, and the theory in itself is still correct 
though its application should be restricted to soils con- 
taining plenty of lime, so that the acidity of the 
manure may be immediately absorbed by the alkali 
in the soil. Indeed, at first, sulphuric acid being 
expensive, it was only used in small proportion, and 
great caution was observed in the mixing arrange- 
ments. Only a portion of the phosphates in the 
coprolites was rendered soluble in water, amounting 
perhaps to 20 per cent, in the manure produced, and 
frequently as much as 8 to 10 per cent, was left in 
the form of insoluble or undissolved phosphate of 
lime. Consequently, in those days, superphosphate 
was sent out in an excellent dry condition, and this 
in itself contributed very materially to increase 
the sale and render the new manure popular among 
farmers, for there were never any complaints about 
the damp acid condition of the manure. 
When acid, however, became cheaper as the result 
of improved mannfaoture from less costly materials, 
and as competition increased on the expiration 
of the original patent rights, sulphuric acid was 
added in greater quantity, and the utmost possible 
amount of soluble phosphate was obtained, so that 
only 2 or 3 per cent, of phosphate of lime was left in 
a condition insoluble in water. Superphosphate then 
became damper and more acid, so that complaints 
respecting its bad condition were of frequent occur- 
rence. Supherphosphato when first introduced was 
chiefly applied as a manure for turnips and swedes 
raised on good arable land containing sufficient lime, 
yet there appears to have been some doubt raised 
in the mind of so kaen an observer and experi- 
mentalist as the late Dr. Augustus Voeloker, F.R.S., 
as to whether aoid manures were not conducive to 
disease in these roots. 
At any rate, as early as 18G3 wo find him writing in 
the "Journal of the Royal Agricultural Society " upon 
'■ Phosphatic Manures for Root Ciops " as follows: — 
"Superphosphate of lime applied to root crops 
has a different practical effect on different soils. 
Purely mineral superpho sphtes f lil to produce gojd 
turnip crops on light sandy soil^. It has indeed been 
observed that the exclusive use of superphosphate, 
