Manufacture of Indigo.--Loading the vats.--Beating.--Boiling,
straining, and pressing.--Scene in the Factory.--Fluctuation of
produce.--Chemistry of Indigo.
Indigo is manufactured solely from the leaf. When arrangements have
been made for cutting and carting the plant from the fields, the vats
and machinery are all made ready, and a day is appointed to begin
'Mahye' or manufacture. The apparatus consists of, first, a strong
serviceable pump for pumping up water into the vats: this is now mostly
done by machinery, but many small factories still use the old Persian
wheel, which may be shortly described as simply an endless chain of
buckets, working on a revolving wheel or drum. The machine is worked by
bullocks, and as the buckets ascend full from the well, they are
emptied during their revolution into a small trough at the top, and the
water is conveyed into a huge masonry reservoir or tank, situated high
up above the vats, which forms a splendid open air bath for the planter
when he feels inclined for a swim. Many of these tanks, called
_Kajhana_, are capable of containing 40,000 cubic feet of water or
more.
Below, and in a line with this reservoir, are the steeping vats, each
capable of containing about 2000 cubic feet of water when full. Of
course the vats vary in size, but what is called a _pucca_ vat is of
the above capacity. When the fresh green plant is brought in, the carts
with their loads are ranged in line, opposite these loading vats. The
loading coolies, 'Bojhunneas'--so called from '_Bojh_,' a bundle--jump
into the vats, and receive the plant from the cart-men, stacking it up
in perpendicular layers, till the vat is full: a horizontal layer is
put on top to make the surface look even. Bamboo battens are then
placed over the plant, and these are pressed down, and held in their
place by horizontal beams, working in upright posts. The uprights have
holes at intervals of six inches. An iron pin is put in one of the
holes; a lever is put under this pin, and the beam pressed down, till
the next hole is reached and a fresh pin inserted, which keeps the beam
down in its place. When sufficient pressure has been applied, the
sluice in the reservoir is opened, and the water runs by a channel into
the vat till it is full. Vat after vat is thus filled till all are
finished, and the plant is allowed to steep from ten to thirteen or
fourteen hours, according to the state of the weather, the temperature
of the water, and other conditions and circumstances which have all to
be carefully noted.
At first a greenish yellow tinge appears in the water, gradually
deepening to an intense blue. As the fermentation goes on, froth forms
on the surface of the vat, the water swells up, bubbles of gas arise to
the surface, and the whole range of vats presents a frothing, bubbling,
sweltering appearance, indicative of the chemical action going on in
the interior. If a torch be applied to the surface of a vat, the
accumulated gas ignites with a loud report, and a blue lambent flame
travels with amazing rapidity over the effervescent liquid. In very hot
weather I have seen the water swell up over the mid walls of the vats,
till the whole range would be one uniform surface of frothing liquid,
and on applying a light, the report has been as loud as that of a small
cannon, and the flame has leapt from vat to vat like the flitting
will-o'-the-wisp on the surface of some miasmatic marsh.
When fermentation has proceeded sufficiently, the temperature of the
vat lowers somewhat, and the water, which has been globular and convex
on the surface and at the sides, now becomes distinctly convex and
recedes a very little. This is a sign that the plant has been steeped
long enough, and that it is now time to open the vat. A pin is knocked
out from the bottom, and the pent-up liquor rushes out in a golden
yellow stream tinted with blue and green into the beating vat, which
lies parallel to, but at a lower level than the loading vat.
Of course as the vats are loaded at different hours, and the steeping
varies with circumstances, they must be ready to open also at different
intervals. There are two men specially engaged to look after the
opening. The time of loading each one is carefully noted; the time it
will take to steep is guessed at, and an hour for opening written down.
When this hour arrives, the _Gunta parree_, or time-keeper, looks at
the vat, and if it appears ready he gets the pinmen to knock out the
pin and let the steeped liquor run into the beating vat.
Where there are many vats, this goes on all night, and by the morning
the beating vats are all full of steeped liquor, and ready to be
beaten.
The beating now is mostly done by machinery; but the old style was very
different. A gang of coolies (generally Dangurs) were put into the
vats, having long sticks with a disc at the end, with which, standing
in two rows, they threw up the liquor into the air. The quantity forced
up by the one coolie encounters in mid air that sent up by the man
standing immediately opposite to him, and the two jets meeting and
mixing confusedly together, tumble down in broken frothy masses into
the vat. Beginning with a slow steady stroke the coolies gradually
increase the pace, shouting out a hoarse wild song at intervals; till,
what with the swish and splash of the falling water, the measured beat
of the _furrovahs_ or beating rods, and the yells and cries with which
they excite each other, the noise is almost deafening. The water, which
at first is of a yellowish green, is now beginning to assume an intense
blue tint; this is the result of the oxygenation going on. As the blue
deepens, the exertions of the coolie increase, till with every muscle
straining, head thrown back, chest expanded, his long black hair
dripping with white foam, and his bronzed naked body glistening with
blue liquor, he yells and shouts and twists and contorts his body till
he looks like a true 'blue devil.' To see eight or ten vats full of
yelling howling blue creatures, the water splashing high in mid air,
the foam flecking the walls, and the measured beat of the _furrovahs_
rising weird-like into the morning air, is almost enough to shake the
nerve of a stranger, but it is music in the planter's ear, and he can
scarce refrain from yelling out in sympathy with his coolies, and
sharing in their frantic excitement. Indeed it is often necessary to
encourage them if a vat proves obstinate, and the colour refuses to
come--an event which occasionally does happen. It is very hard work
beating, and when this constant violent exercise is kept up for about
three hours (which is the time generally taken), the coolies are pretty
well exhausted, and require a rest.
[Illustration: INDIGO BEATERS AT WORK IN THE VATS.]
During the beating, two processes are going on simultaneously. One is
chemical--oxygenation--turning the yellowish green dye into a deep
intense blue: the other is mechanical--a separation of the particles of
dye from the water in which it is held in solution. The beating seems
to do this, causing the dye to granulate in larger particles.
When the vat has been beaten, the coolies remove the froth and scum
from the surface of the water, and then leave the contents to settle.
The fecula or dye, or _mall_, as it is technically called, now settles
at the bottom of the vat in a soft pulpy sediment, and the waste liquor
left on the top is let off through graduated holes in the front. Pin
after pin is gradually removed, and the clear sherry-coloured waste
allowed to run out till the last hole in the series is reached, and
nothing but dye remains in the vat. By this time the coolies have had a
rest and food, and now they return to the works, and either lift up the
_mall_ in earthen jars and take it to the mall tank, or--as is now more
commonly done--they run it along a channel to the tank, and then wash
out and clean the vat to be ready for the renewed beating on the
morrow. When all the _mall_ has been collected in the mall tank, it is
next pumped up into the straining room. It is here strained through
successive layers of wire gauze and cloth, till, free from dirt, sand
and impurity, it is run into the large iron boilers, to be subjected to
the next process. This is the boiling. This operation usually takes two
or three hours, after which it is run off along narrow channels, till
it reaches the straining-table. It is a very important part of the
manufacture, and has to be carefully done. The straining-table is an
oblong shallow wooden frame, in the shape of a trough, but all composed
of open woodwork. It is covered by a large straining-sheet, on which
the mall settles; while the waste water trickles through and is carried
away by a drain. When the mall has stood on the table all night, it is
next morning lifted up by scoops and buckets and put into the presses.
These are square boxes of iron or wood, with perforated sides and
bottom and a removeable perforated lid. The insides of the boxes are
lined with press cloths, and when filled these cloths are carefully
folded over the _mall_, which is now of the consistence of starch; and
a heavy beam, worked on two upright three-inch screws, is let down on
the lid of the press. A long lever is now put on the screws, and the
nut worked slowly round. The pressure is enormous, and all the water
remaining in the _mall_ is pressed through the cloth and perforations
in the press-box till nothing but the pure indigo remains behind.
The presses are now opened, and a square slab of dark moist indigo,
about three or three and a half inches thick, is carried off on the
bottom of the press (the top and sides having been removed), and
carefully placed on the cutting frame. This frame corresponds in size
to the bottom of the press, and is grooved in lines somewhat after the
manner of a chess-board. A stiff iron rod with a brass wire attached is
put through the groove under the slab, the wire is brought over the
slab, and the rod being pulled smartly through brings the wire with it,
cutting the indigo much in the same way as you would cut a bar of soap.
When all the slab has been cut into bars, the wire and rod are next put
into the grooves at right angles to the bars and again pulled through,
thus dividing the bars into cubical cakes. Each cake is then stamped
with the factory mark and number, and all are noted down in the books.
They are then taken to the drying house; this is a large airy building,
with strong shelves of bamboo reaching to the roof, and having narrow
passages between the tiers of shelves. On these shelves or _mychans_,
as they are called, the cakes are ranged to dry. The drying takes two
or three months, and the cakes are turned and moved at frequent
intervals, till thoroughly ready for packing. All the little pieces and
corners and chips are carefully put by on separate shelves, and packed
separately. Even the sweepings and refuse from the sheets and floor are
all carefully collected, mixed with water, boiled separately, and made
into cakes, which are called 'washings.'
During the drying a thick mould forms on the cakes. This is carefully
brushed off before packing, and, mixed with sweepings and tiny chips is
all ground up in a hand-mill, packed in separate chests, and sold as
dust. In October, when _mahye_ is over, and the preparation of the land
going on again, the packing begins. The cakes, each of separate date,
are carefully scrutinised, and placed in order of quality. The finest
qualities are packed first, in layers, in mango-wood boxes; the boxes
are first weighed empty, re-weighed when full, and the difference gives
the nett weight of the indigo. The tare, gross, and nett weights are
printed legibly on the chests, along with the factory mark and number
of the chest, and when all are ready, they are sent down to the brokers
in Calcutta for sale. Such shortly is the system of manufacture.
During _mahye_ the factory is a busy scene. Long before break of day
the ryots and coolies are busy cutting the plant, leaving it in green
little heaps for the cartmen to load. In the early morning the carts
are seen converging to the factory on every road, crawling along like
huge green beetles. Here a cavalcade of twenty or thirty carts, there
in clusters of twos or threes. When they reach the factory the loaders
have several vats ready for the reception of the plant, while others
are taking out the already steeped plant of yesterday; staggering under
its weight, as, dripping with water, they toss it on the vast
accumulating heap of refuse material.
Down in the vats below, the beating coolies are plashing, and shouting,
and yelling, or the revolving wheel (where machinery is used) is
scattering clouds of spray and foam in the blinding sunshine. The
firemen stripped to the waist, are feeding the furnaces with the dried
stems of last year's crop, which forms our only fuel. The smoke hovers
in volumes over the boiling-house. The pinmen are busy sorting their
pins, rolling hemp round them to make them fit the holes more exactly.
Inside the boiling-house, dimly discernible through the clouds of
stifling steam, the boilermen are seen with long rods, stirring slowly
the boiling mass of bubbling blue. The clank of the levers resounds
through the pressing-house, or the hoarse guttural 'hah, hah!' as the
huge lever is strained and pulled at by the press-house coolies. The
straining-table is being cleaned by the table 'mate' and his coolies,
while the washerman stamps on his sheets and press-cloths to extract
all the colour from them, and the cake-house boys run to and fro
between the cutting-table and the cake-house with batches of cakes on
their heads, borne on boards, like a baker taking his hot rolls from
the oven, or like a busy swarm of ants taking the spoil of the granary
to their forest haunt. Everywhere there is a confused jumble of sounds.
The plash of water, the clank of machinery, the creaking of wheels, the
roaring of the furnaces, mingle with the shouts, cries, and yells of
the excited coolies; the vituperations of the drivers as some terrified
or obstinate bullock plunges madly about; the objurgations of the
'mates' as some lazy fellow eases his stroke in the beating vats; the
cracking of whips as the bullocks tear round the circle where the
Persian wheel creaks and rumbles in the damp, dilapidated wheel-house;
the-dripping buckets revolving clumsily on the drum, the arriving and
departing carts; the clang of the anvil, as the blacksmith and his men
hammer away at some huge screw which has been bent; the hurrying crowds
of cartmen and loaders with their burdens of fresh green plant or
dripping refuse;--form such a medley of sights and sounds as I have
never seen equalled in any other industry.
The planter has to be here, there, and everywhere. He sends carts to
this village or to that, according as the crop ripens. Coolies must be
counted and paid daily. The stubble must be ploughed to give the plant
a start for the second growth whenever the weather will admit of it.
Reports have to be sent to the agents and owners. The boiling must be
narrowly watched, as also the beating and the straining. He has a large
staff of native assistants, but if his _mahye_ is to be successful, his
eye must be over all. It is an anxious time, but the constant work is
grateful, and when the produce is good, and everything working
smoothly, it is perhaps the most enjoyable time of the whole year. Is
it nothing to see the crop, on which so much care has been expended,
which you have watched day by day through all the vicissitudes of the
season, through drought, and flood, and blight; is it nothing to see it
safely harvested, and your shelves filling day by day with fine sound
cakes, the representatives of wealth, that will fill your pockets with
commission, and build up your name as a careful and painstaking
planter?
'What's your produce?' is now the first query at this season, when
planters meet. Calculations are made daily, nay hourly, to see how much
is being got per beegah, or how much per vat. The presses are calculated
to weigh so much. Some days you will get a press a vat, some days it
will mount up to two presses a vat, and at other times it will recede
to half a press a vat, or even less. Cold wet weather reduces the
produce. Warm sunny weather will send it up again. Short stunted plant
from poor lands will often reduce your average per acre, to be again
sent up as fresh, hardy, leafy plant comes in from some favourite
village, where you have new and fertile lands, or where the plant from
the rich zeraats laden with broad strong leaf is tumbled into the
loading vat.
So far as I know, there seems to be no law of produce. It is the most
erratic and incomprehensible thing about planting. One day your presses
are full to straining, next day half of them lie empty. No doubt the
state of the weather, the quality of your plant, the temperature of the
water, the length of time steeping, and other things have an influence;
but I know of no planter who can entirely and satisfactorily account
for the sudden and incomprehensible fluctuations and variations which
undoubtedly take place in the produce or yield of the plant. It is a
matter of more interest to the planter than to the general public, but
all I can say is, that if the circumstances attendant on any sudden
change in the yielding powers of the plant were more accurately noted;
if the chemical conditions of the water, the air, and the raw material
itself, more especially in reference to the soil on which it grows, the
time it takes in transit from the field to the vat, and other points,
which will at once suggest themselves to a practical planter, were more
carefully, methodically, and scientifically observed, some coherent
theory resulting in plain practical results might be evolved.
Planters should attend more to this. I believe the chemical history of
indigo has yet to be written. The whole manufacture, so far as
chemistry is concerned, is yet crude and ill-digested. I know that by
careful experiment, and close scientific investigation and observation,
the preparation of indigo could be much improved. So far as the
mechanical appliances for the manufacture go, the last ten years have
witnessed amazing and rapid improvements. What is now wanted, is, that
what has been done for the mere mechanical appliances, should be done
for the proper understanding of the chemical changes and conditions in
the constitution of the plant, and in the various processes of its
manufacture[1].
[1] Since the above chapter was written Mons. P.I. Michea, a French
chemist of some experience in Indigo matters, has patented
an invention (the result of much study, experiment, and
investigation), by the application of which an immense increase in
the produce of the plant has been obtained during the last season,
in several factories where it has been worked in Jessore, Purneah,
Kishnaghur, and other places. This increase, varying according to
circumstances, has in some instances reached the amazing extent
of 30 to 47 per cent., and so far from being attended with a
deterioration of quality the dye produced is said to be finer than
that obtained under the old crude process described in the above
chapter. This shows what a waste must have been going on, and what
may yet be done, by properly organised scientific investigation.
I firmly believe that with an intelligent application of the
principles of chemistry and agricultural science, not only to the
manufacture but to growth, cultivation, nature of the soil,
application of manures, and other such departments of the
business, quite a revolution will set in, and a new era in the
history of this great industry will be inaugurated. Less area for
crop will be required, working expenses will be reduced, a greater
out-turn, and a more certain crop secured, and all classes,
planter and ryot alike, will be benefited.
[Illustration: INDIAN FACTORY PEON.]
[Illustration: INDIGO PLANTER'S HOUSE.]