556 
NATURE : 
[April 13, 1882 
It would seem almost too late for the Government of 
India itself to undertake the manufacture of iron. Per- 
haps had it done so, prior to the opening up of its fine 
system of railways it might have done good, keeping 
money in the country and employing labour, but there were 
many and serious objections to such government esta- 
blishments. In the meanwhile, here and there through- 
out India iron is still manufactured. 
The earthy varieties of the heematites, or red and 
yellow ochres, are abundant in India. They are used by 
the natives as mineral pigments under the collective term 
of givn, for the adornment of the walls of houses and 
huts, and sometimes to make the caste marks on the 
foreheads of the Hindus. 
In the Gabalpur district a paint is manufactured by 
grinding the ore to an impalpable powder by means of 
grindstones worked by small water-wheels. The powder 
is packed in bags, and sells retail at a price so high as 
13/.aton. It has proved to be the cheapest paint in the 
Indian market. It lies smoothly on wood or iron, and 
has been successfully used against damp or porous tiles, 
bricks, and plaster. It has already stood a good practical 
test on the metal work of the principal bridges in India. 
So far as the cealand iron products of this great depen- 
dency of ours are concerned, they would seem more than 
sufficient for all her needs, but at prices that were alone 
remunerative when the country remained isolated from 
the rest of the world. By competition the native produc- 
tion has been almost starved out, but the native con- 
sumers get as good an article, and at a far cheaper rate 
now than of old. 
Salt is the mineral product of all others, the most im- 
portant to the revenue of India, the gross annual re- 
ceipts from the salt-tax being now about seven millions of 
pounds sterling. While the native supply is practically 
inexhaustible, there is still a steady import trade from 
foreign countries. Within the last ten or twelve years, a 
great deal has been done in the way of equalising the 
salt-tax in the different districts of India, and the Go- 
vernment monopoly is now fairly complete. In Madras 
the indigenous sources of supply have been the salt- 
pans on the coastal districts, where salt is obtained by 
the evaporation of sea water. It was also obtained at 
one time by the lixiviation of saline earth. The salt 
manufacture begins in January, as soon as the rains are 
over and the weather begins to get warm. Before the 
evaporation at the pans begins, there is a preliminary 
evaporation, lasting over some twenty-five days, in pits, 
by which the brine is reduced 50 or 75 per cent. in bulk. 
‘The manufacture in the pans continues for about twenty- 
nine days, when the salt is taken out and stored on the 
bauks to dry. The brine is not evaporated to dryness in 
the pans, in order that the magnesium sulphate may, as 
much as possible, remain in solution. In Rajputana, 
there are four sources of salt. The most extensive are 
the salt lakes, such as Sambhar and Didwana; next 
come the brine-pits, then some salt is obtained from 
saline efflorescence from earthwork, and some from de- 
posits in old river-pits. A brine-pit in Bhartpur, exa- 
mined in 1865, contained 20 to 30 feet of brine at a depth 
of 20 feet from the surface, and was reported to have 
shown no diminution of supply during the preceding 
twenty-eight years. 
The Punjab is distinguished from all the other districts 
of India, in possessing enormous deposits of rock-salt, 
and it is very remarkable that these deposits do not all 
belong to the one geological age, but are referable to very 
distinct periods which are widely separated in time. 
During the year ending March 31,1880, inland customs duty 
was paid on 55,000 tons of salt from the rock-salt mines of 
the Punjab. The rock-salt of the Kohet district would 
seem to be of Eocene age; it is overlaid conformably by 
gypsum, which is again overlaid by rocks of Nummulitic 
age. Here the salt is obtained by open quarrying. The 
quarries at Malgin have been worked from time imme- 
morial ; those at Bhadur Khel were opened some twelve 
centuries ago. The total available quantity of salt in 
these quarries has been estimated to afford a supply, 
which, allowing a liberal margin for waste, would, at the 
rate of the present demand, last for 4000 years. 
The Salt-range deposit is the oldest-known deposit in 
the world. It underlies beds containing Silurian deposits, 
and is therefore of a period at least not younger than the 
Silurian age. The rock-salt in this range is worked un- 
derground. The largest mines of the range are the Mayo 
mines at Khewra, on the eastern side of the Indus. These 
and the neighbouring mines had been worked most of 
all, and generally on a most dangerous system. Thus, in 
one of the Mayo mines the old Sikh workmen having 
worked out the salt in one vast chamber, the roof of which 
which was supported by two immense pillars, commenced 
and worked outa second chamber under the first one, and 
beneath the pillar supporting its roof, with the result that 
on a Sunday, in June, 1870, one of these pillars broke 
through, carrying with it a large part of the roof, and 
forming a crater on the hill where the mine is situated. 
Since then, these mines have been worked in accordance 
with modern principles, and the appearance of their tun- 
nels, drifts, and tramways is most imposing. There is 
even a wire-rope tramway to the nearest village from the 
mouth of the mines. The annual average receipts from 
the Salt-range Mines is 388,1447. 
In connection with salt, the subject of Reh is a highly 
important one. ef is the native term applied to efflor- 
escent salts which have accumulated in the soil or in the 
subsoil waters of large tracts in India, and this, in some 
places, to such an extent that cultivation has become im- 
possible, and fertile fields have become barren spaces. 
The origin of this Reh is now fully understood ; the rivers 
carry in solution saline particles washed out of the rocks 
over which they flow; as well asa fine silt or alluvium, 
which also, on its decomposition, yields further salts; in 
a region of intense evaporation, and where the surface of 
the ground is constantly irrigated, if there be no free 
drainage outlet for the waters, the salts contained in 
them are accumulated in the soil, or still further surcharge 
the subsoil waters ; while over and above all this, during 
the rainy reason the rain-water, charged with carbonic 
acid, falling on the porous soil, has the effect of decom- 
posing its mineral constituents and of carrying down to 
the subsoil the salts then formed. This being the state 
of things, when the surface of the ground becomes dried, 
the water, charged with salts, rises up and evaporates, 
leaving a salt efflorescence, the ve, which at length so 
permeates the superficial layer of soil as to leave it little 
better than a salt marsh. Contrary to what might on 
first sight be expected, irrigation by even pure canal 
water seems to increase the evil; for, as Mr. Medlicott 
has so well pointed out, the table of salt subsoil water is, 
by the addition of the canal water, raised to a height that 
brings it within the reach of evaporation; and so the 
efflorescence is increased. The only remedies for this 
state of things would seem to be good, deep subsoil 
drainage, with thorough washing of the surface soil, and 
protecting the latter as much as possible from evaporation. 
India at one time enjoyed almost a monopoly of the 
saltpetre trade, and even still, from the port of Calcutta, 
in the year 1879-80, the export of this commodity was 
nearly 432,000/. The peculiar habits of the people and 
the fact that in the saltpetre- roducing districts there is a 
long period of drought after a long period of rain, 
accounts for the soil in the vicinity of the Indian villages 
being impregnated with this salt. More than two-thirds 
of the total quantity of the saltpetre which is exported 
from Calcutta at present comes from the districts of 
Tirhut, Saran. and Champaran in Behar. ; 
The Building Stones of India form a wonderfully inter- 
esting subject. Among the most abiding records of any 
