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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.

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 splashing, 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 manufacture¹.

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.

Indian Factory Peon

Indigo Planter's House