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Iron in Ancient India c8.s1: Ores and Mines of Iron in Ancient India

Iron in Ancient India c8.s1

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Ores and Mines of Iron in Ancient India

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From the enormous deposits of iron slag and cinder in many parts of India it is evident that iron was extensively manufactured from its ores in various places throughout India. The ores of iron described in the Arthashāstra of Kautilya, as mentioned before, are evidently hæmatites. Hæmatites were known in Hindu medico-chemical literature as gairik, and the bright red variety or red hæmatite was called subarna gairik (golden gairik).¹ Gairik is mentioned in the Amarkosha. It was also used as a dye for dyeing clothes. Iron pyrites was known in Aurvedic literature as tāpya or rauppa-mākhika (silver pyrites). Two varieties of tāpya are mentioned in Charaka and Sushruta (third century B.C.) and latterly copper and iron pyrites were designated as swarna-mākhika (golden pyrites) and rauppa-mākhika.

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¹ सुवर्णगैरिकं तु धान्यतनो रक्ततरं हि तत् । भावप्रकाश ।

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In the Ayeen Akbari we find that during Akbar's time there were iron mines in Bajuha, subah Bengal, in Keroh, subah Kashmir, and in Kumāun within the Delhi subah, also at Nirmul and Indore to the north of Golconda where excellent iron and steel were obtained. Tavernier in his "Travels" mentions that there were gold, silver, steel, lead and iron mines in Assam² and that iron manufactured at Haidrabad was pure.³ Manucci wrote that iron was abundant in Golconda which was principally celebrated for diamond mines. The Dhātukriyā, a work of the sixteenth century mentions that iron ores were plentiful in Lohādri, Gayādri, Gautamādri, Vindya Hills, Nalādri, Trymbaka and seaside places. It must be understood that these references are merely casual and they do not give any systematic information regarding the existence of iron mines in ancient India.

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² Tavernier's "Travels in India," Vol. II, pp. 281, 284.

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³ Tavernier, ibid., Vol. I, p. 157.

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"DIRECT" PROCESS OF MANUFACTURING WROUGHT IRON.

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The ancient method of manufacturing iron still prevails in various parts of the country, notably in Orissa, Chota Nagpur, Central Provinces, Baroda, the Deccan and Carnate, and North-Western Provinces. It has mainly passed into the hands of ignorant and in many places aboriginal tribes, but it is certain that in early times the Delhi and the Dhar pillars and the Orissan beams must have been forged by skilled metallurgists (लोहमालवित्) and engineers. Any one who studies the growth and decay of the intellectual and scientific activities of the Hindoos will see clearly that scientific industries were declining from a long time, and owing to a lack of initiative the old processes struggled on on a continuously diminutive scale until almost all industries passed into the hands of the least advanced sections of the Hindu community. It has already been stated that the iron beams of the temples in Orissa, which was famous for her iron in all ages, may have been prepared from iron manufactured in the Talchir districts where iron-smelting is still carried on by the Kols. Mr. H. F. Blandford of the Geological Survey of India says, "The iron smelters of Talchir and neighbouring districts belong to the large tribe of Cols . . . lumps of slag are frequently found in jungly districts where no iron manufacture has been carried on within the memory of the inhabitants." The author also guesses that the iron of the Delhi and Mount Abu pillars was probably obtained from Rajputana, as large hillocks of iron-slag are found in Khetri and other places in Rajputana, which is now being utilised as a flux by the native copper smelters. The iron of the Dhar pillar evidently has come from Southern India which was famous, until recently, for iron and steel.

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It is a matter for regret that Sanskrit literature, as far as is known to the author, contains little or no information regarding the actual method of the manufacture of iron or the furnaces employed in smelting the ores or in forging iron, though we can easily conceive that the furnaces, which forged the Delhi and other pillars even piece by piece, must have been of great dimensions. There existed undoubtedly *lohasāstras* or "sciences of iron (or metals)", the author of one of which was Patanjali, who flourished in the second century B.C. and was the commentator of the celebrated grammarian Pānini. These unfortunately have all perished. Ball speaks only what is half true when he says, " The rude smelting-furnaces of the natives . . . are probably to a great extent the lineal descendants of a system of iron manufacture, which, in the earliest times of which we have any record, must have been on a scale of considerable magnitude."¹ We may, however, readily admit that the principle followed in the existing indigenous method of manufacturing iron was probably the same in ancient times, though iron must have been produced in India on a very large scale and in much bigger furnaces by intelligent Hindu workers.

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¹ Ball's "Geology of India," Part III, p. 340.

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Fortunately we have got accounts of the manufacture of iron in India left by Dr. Buchanan who visited India in 1800, and by Heyne whose "Tracts on India" was published in 1814 embodying the results of his observations from 1794. In the accounts of these travellers we find descriptions of the process of manufacturing iron as it existed more than a hundred years ago. The process described in these books as well as that which exists even now may be called the "direct process" of manufacturing wrought iron or malleable iron—a process which does not require the previous preparation of cast-iron. The modern European process of making wrought iron may be called the "indirect process" in which wrought iron is obtained by the almost total removal of carbon from cast iron which is first directly obtained from the ores. This direct process of manufacturing wrought iron, which has existed in India from very ancient times, is still carried on not only in India but also in "Borneo and Africa; nor indeed is it yet extinct in Europe: it is stated, moreover, to be still extensively employed in Vermont and New Jersy, U.S."[²] We may safely conclude that the iron of the Delhi and Dhar pillars and of the Orissan beams was prepared from iron ores by this direct process.

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² Percy's "Metallurgy," Vol. II, p. 254.

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The rationale of the process is as follows:—Only the richest ores of iron are employed, and the fuel as well as the reducing agent is charcoal. The blast furnace consists of a hearth with a circular shaft or chimney from 2 to 6 feet high and 2 to 3 feet broad, and the blast is admitted with a hand-bellows through a hole. As charcoal is a much purer form of carbon than coal the iron produced by heating the ores with charcoal is exceedingly pure. No flux seems to have been used as only pure ores were employed, though Dr. Verchere testifies that in Wariristan a flux of limestone is added even at the present day. The malleable iron thus obtained directly from the ores is hammered in the hot condition in order to make the iron solid and homogeneous. The iron slag during the process of heating is tapped off from time to time through another hole or tuyere, and the adhering portion of it is squeezed out during the hammering. The iron seems to have been obtained as lumps and not in the molten condition.

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Heyne in his "Tracts" gives an account of iron manufacture as he saw in the Northern Circars which he visited in 1794, also at Yeragutty near Satgur and at Ramanakapetta near Nuzid.¹ At the first place the ores employed were a kind of iron-stone having the appearance of yellow and brown ochre. At the second place the ores were a kind of "fine black sand found in small rivulets or nullahs that derive their source from the neighbouring mountains"—a "sub-species of micaceous iron ore" very rich in iron and attracted powerfully by the magnet. In the third place the ores used were hæmatites.

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¹ Heyne's "Tracts on India." pp. 189, 218, 224.

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Heyne gives a drawing of an iron-furnace used at Yeragutty which is reproduced here. "The furnaces are made of red loam mixed with sand and consists of two parts. The lower and larger is about three spaces high and a foot in diameter; quite cylindrical, and erected over a hole in the ground, about four inches deep; its sides are everywhere about two inches thick. The upper part is conical, with the higher portion of the cone reversed. It is about eighteen inches high, and at the opening not quite a foot in diameter. The bellows are of a kind used by the iron smiths, and made of sheep's skin: a hole is left near the bottom of the cylindrical part of the furnace to receive their nozzle." When smelting iron the two parts of the furnace are cemented with some loam and the bottom is filled with charcoal which is then ignited. One part of ore and four parts of charcoal are added at a time at the interval of about fifteen minutes, and the bellows are worked. This produces sufficient heat, if not to melt the iron, at least to [Figure: Iron Furnace. (Heyne's Tracts on India, 1814, page 190)]

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soften it, and at the end of the operation the iron is found in a solid mass at the bottom of the furnace which is put a second time into the fire and subjected to the action of the hammer.

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At the Northern Circars and at Ramanakapetta the furnaces, described by Heyne, are bigger in size and semicircular in shape " very much resembling in shape the half a hen's egg divided longitudinally with the largest end uppermost." The wall is built of clay and the height 4½ feet and breadth 3 feet 9 inches. The external and convex surface has one of its sides, at the bottom, an excavation serving to receive the slag which is let out through a hole in the bottom. The mode of the construction of the inner part of the furnace is somewhat different. The ore and charcoal are used in the proportion of one to two. The iron obtained is also in the solid condition.

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Buchanan who visited Southern India in 1800 saw in Malabar iron manufacture from black iron sand in which the greater part of the Malabar Hills abounds. He also saw the same method of manufacturing iron from black iron sand on his way from Serangapatam to Bangalore and from both stone-ore and sand-ore in the districts of Madhugiri, Chin-nārāyan-durga, Hagalawadi, and Devaraya-durga. The methods and furnaces used are much the same as described by Heyne, the iron being obtained in the solid condition showing that the heat in the furnaces was sufficient only for softening the metal.¹ The reason for the comparative lowness of the temperature is the want of powerful bellows.

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¹ For details the reader is referred to Buchanan's "Travels from Madras through Mysore, Canara and Malabar," Vol. I, pp. 118 and 306, Vol. II, 118, in which sketches and sections of the furnaces used in making iron and steel are given.

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Dr. Percy in his "Metallurgy" gives an elaborate description of the furnaces used and processes employed from the reports of the Geological Survey of India, from which we can learn how iron was manufactured in the middle of the nineteenth century as Percy's work was published in 1864. He writes: "The ores employed are magnetic oxide and rich red and brown hæmatites. Captain Campbell states he has seen specular iron ore used by the Konds of Goomsoor. The process of smelting varies somewhat in different districts; and this variation is due partly to local custom and partly to the fact that the art has most advanced where the population is most dense and civilized. The furnaces may be divided into three typical kinds. The first kind is employed on the west coast of India, in the Western Ghats and usually through the Deccan and Carnatic and is the rudest form of furnace in use in the less civilized districts and among the Hill tribes. The *second* and *third* are employed in Central India and the North-Western Provinces and resemble the simplest forms of the Catalan forge and the German Stückofen respectively: they are greatly in advance of the first and are capable of producing wrought-iron in considerable quantity as well as natural steel." (For details and diagrams consult the book).¹

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¹ Percy's Metallurgy, Vol. II, p. 253 *et seq.*

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WHY WROUGHT IRON AND NOT CAST IRON IS PRODUCED BY THE INDIAN PROCESS.

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It will be seen that the iron produced in the first place by the Indian method is always wrought iron and not cast-iron which is produced as the first product in modern blast furnaces. The reason is not far to seek. It will appear from the accounts of manufacture given above that the temperature in the furnaces is only sufficient to soften the iron so that small particles might agglutinate to each other but not sufficient to melt it, while the temperature at the hottest zone of a modern blast furnace is 1400° or more. The result is that in a modern blast furnace the iron begins to take up carbon at 1000° and becomes saturated with the latter as it descends to the zone in which the temperature is 1400°, thus becoming converted into cast iron. It must however be admitted that at the lower temperature of the Indian furnaces a large portion of the iron ores escapes reduction to metallic iron.

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