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A Concise History of Science in India c9.s3: The Post-Vedic Period and the Classical Age

A Concise History of Science in India c9.s3

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English

Contents

The Post-Vedic Period and the Classical Age

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The post-Vedic period and later the Classical Age of India (*c.* 600 B.C.–A.D. 740) afford substantial evidence which testifies to the Indian chemical knowledge and practices of far greater import. Discernibly the chemical knowledge became refined and practices culminated in notable feats of excellence during this period. They include the production of glass and pottery, fermentation methods and dyeing techniques. Recent archaeological evidence sheds fresh light on the new achievements in glass and ceramic ware as well as metallurgical operation. There are a number of literary sources belonging to this period giving information of value on various chemical practices. Of them, particular mention may be made of the *Arthaśāstra* by Kauṭilya, the two Āyurvedic classics, the *Caraka* and the *Suśruta Saṃhitās* (original compositions may belong to the early centuries before the Christian era though the extant ones are later), and the *Bṛhatsaṃhitā* by Varāhamihira. What follows is but a brief account, based on the archaeological and literary evidence, of some of the well-known chemical practices.

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a *RV.*, X. 72.2; Banerjee (M. N.), pp. 432 ff.

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b Forbes, p. 239.

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c Warmington, pp. 257–58.

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d Forbes, p. 239.

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e Op. cit., pp. 239–40.

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*Glass*

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The term glass covers a wide range of substances which may differ in chemical composition and some physical properties but which possess the essential characteristics of having cooled from a state of fusion to a solid state without crystallization (under-cooling). Chemically glass is regarded as a mixture of silicates.

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Though it is not clear when and where the invention of glass occurred first in the old world either in Mesopotamia or Egypt, it is now recognized that the specimens of blue glass found at Tell Asmar (in Mesopotamia) are attributable to a period *c.* 2700–2600 B.C. The cemeteries of Ur III (*c.* 2100 B.C.) and also at Assur under the Ziggurat (*c.* 1800 B.C.) in Mesopotamia have yielded glass beads. It would appear that not only glass was known in Egypt by about 2000 B.C. at the time of the XII Dynasty but even there were real glass factories there by about the fifteenth century B.C. at the time of the XVIII Dynasty in the reign of Amenhotep II (1448–1420 B.C.). Remains of a glass house and fragments of glass in several stages of manufacture have been found at the city of Tell el Amarna (1450–1400 B.C.).a, b

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In India the Mohenjo-daro and Harappan sites have not given clues to the effect that the use of glass was known there; only glazedc beads of steatite or faience have been largely found. A few early objects of glass in the form of beads have been noticed at Maski, a chalcolithic site in the southern Deccan, pointing to the fact that glass was known in India at least at the beginning of the first millennium B.C.d But in the succeeding centuries, the glass industry steadily gained momentum and began to show signs of technical excellence which seemed to have manifested itself to a remarkable degree in the early centuries of the Christian era, as evidenced by the archaeological finds in over 30 sites. The glass objects (beads, bangles, ear-reels, eye-beads, etc.) unearthed at these sites are in various colours such as blue, green, red, white, yellow, orange and purple. In a few places some tiles and broken parts of vessels have also been found.

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Of the most important sites, mention may be made here of Hastinapur, Taxila, Ujjain, Maheswar, Nasik, Bhita, Ahicchatra, Kopia, Nalanda, Nevasa, Ter, Kolhapur, Kondapur, Prakash, Brahmagiri and Arikamedu.e At Hastinapura have been found beads of black and brownish colour (hardness: 5–6; sp. gr.: 2·55; probably belonging to *c.* 800 B.C.). They are mainly of soda-lime-silicate composition with traces of phosphates and potassium, and their colour is due to the varying amounts of iron compounds in them. At Taxila,b the Bhir Mound has yielded at the sixth–fourth centuries B.C. levels a number of glass beads of several shapes and colours (blue, green, red, orange, amber and black), ear-reel (dark green) with a floral design on it, ‘eye-beads’, glass bangles and seal. As one of the outposts of the north-western frontier of the Mauryan Empire then, Taxila was prone to receive and assimilate foreign influences in the technique of glass production. That this was so has been illustrated amply by the glass objects found later (first century B.C.–first century A.D.) at the new city of Sirkap at Taxila. The foreign glass found at this place has been recognized as lace glass, ribbed ware, swirled glass, blue and white cameo, mosaic and millefiori glass.c The last, it may be noted, which is known for its floral and cellular structure, was commonly produced by the Roman glass technologists, particularly those at Venice. Three glass flasks (sea- and jade-green in colour) and an upper portion of a glass bottle which have been found at Sirkap seem to be Mediterranean in origin, while the glass objects of local manufacture comprise sealings, beads of composite glass, rings, intaglios, discs, lense-like objects and large tiles. Certain specimensd from Taxila have been analysed chemically and, as a result, it has been noticed that the red opaque glass and strips of haematinum contain a very large percentage of lead, while the white opaque and the turquoise blue samples have significant amounts of antimony. The green-blue tiles have a high percentage of silica which confers on them the necessary hardness, and also an appreciable percentage of potash which gives them the desired durability.

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a Forbes, pp. 120 ff.

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b Dikshit (M. G.), pp. 1–2.

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c Glass and glaze, though produced and used differently, are similar from the chemical point of view in the sense they contain soda or some other alkali as a constituent. Glaze is applied generally to the base of some other material. Both glaze and glass are isotropic, e.g., they do not change the colour of light when tested in a polariscope.

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d Thapar (1), pp. 107–109.

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e For a comprehensive treatment of the subject see *History of Glass* by Dikshit, M. G., Bombay, 1969.

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Excavations at Ujjaine have brought to light some beads, ear-reels and bangles in stratum II (*c.* 500–200 B.C.), and those at Maheswar,f an annealed black glass seal which depicts an elephant in a lively posture (*c.* 400 B.C.) and ear-reels of amber colour. At Nasikg have been found ear-reels (*c.* 200 B.C.), gold-foil beads and rings. Bhita and Ahicchatra are the other places where gold-foil beads have also been found along with a number of beads of different colours. Particular mention should be made of the fact that some sites like Kaundinyapura, Ahicchatra, Ujjain, Sravasti and Sirkap have also yielded what are known as ‘stratified eye-beads’,h the technical know-how of which seems to have been borrowed from outside.

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A large number of glass objects which seem to be indicative of the remains of an ancient glass factory (*c.* third century B.C.–third century A.D.) have been observed at Kopiai on the bank of the river Anoma in the Basti district of Uttar Pradesh. They are generally of soda-lime glass (sp. gr.:

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a Lal (Dr. B. B.), pp. 13–23.

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b Beck, pp. 24–28; Ghosh (A.), (1), pp. 41–80.

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c Dikshit (M. G.), pp. 29–31; Marshall, pp. 688–89.

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d Sana Ullah, p. 125.

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e *IAR*, 1956–57, p. 27.

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f Sankalia, Subbarao and Deo, pp. 218–20.

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g Sankalia and Deo, pp. 96–101.

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h Dikshit (M. G.), pp. 17–22.

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i Dikshit (M. G.), p. 39.

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2·33–2·68) with rather a high percentage of aluminium oxide (7–8%) and some iron oxide. Blocks of glass, some of which weigh as much as 120 pounds and measure 18″×12″×9″, have also been discovered

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FIG. 5.6. Sketches of some ancient glass specimens.*a* 1, ear-reel from Taxila; 2–4, seals (Taxila, Maheswar and Patna respectively); 5–6, eye-beads (Bhir Mound, Taxila); 7, bead (Sirkap, Taxila); 8, bead (Ahicchatra); 9, fragment of a blue finger-ring (Ter); 10, wine flask (Taxila); 11, flask in branded agate style (Ter); 12, Roman glass bowls (Arikamedu); 13, bangle piece (Taxila); 14, spirally wound glass bangle (Nevasa); 15, millefiori glass (Arikamedu); and 16, blue glass amulet made in imitation of the *triratna* symbol (Ter).

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at Kopia. Nalanda, an important seat of Buddhist learning in the ancient period, has yielded opaque, blue and green glass objects.

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a Dikshit (M. G.), pp. 4, 11, 19, 30, 35, 42, 45, 50 and 51.

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In the site at Nevasa have been observed beads of different colours including the gold-foil ones as well as small glass vessels in green and blue colours. At Ter have been found beads, finger-ring and a flask of agate-banded type which seems to be of Mediterranean origin. From the excavations at Brahmapuri on the outskirts of the city of Kolhapur have been reported a number of oblate beads of green, blue and yellow colour, and from Kondapur, beads of blue or blue-green glass with copper or cobalt as the colouring agent. The finds at Prakash include opaque as well as polychrome glass bangles and beads.a

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Brahmagirib in the southern Deccan has yielded a number of glass bangles, some of which are black while the others have yellow strips over a grey-coloured base (first–fourth centuries A.D.). At Arikamedu,c an early historical site on the eastern coast south of Madras, have been noticed a number of glass objects both locally produced and imported. The former comprises a number of beads in blue, green and copper-red colour. Of the latter, the noteworthy are the fragments of glass bracelets, beads (sp. gr.: 2·51–2·91; hardness: 5.7) and bowl of whitish iridescent glass and a bluish glass bowl full of bubbles and striae which indicate their Roman origin. It may be noted that there was extensive commercial contact between this region and the Roman world in the early centuries of the Christian era.

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In the Sanskrit texts the term used for glass is *kāca*. Among the well-known literary works which contain references to *kāca* are *Śatapatha Brāhmaṇa*,d *Kauṭilīya Arthaśāstra*,e *Caraka Saṃhitā*,f *Hitopadeśa*g and *Bṛhatsaṃhitā*.h Notwithstanding the fact that both the literary works and the archaeological finds shed light on the use of glass in India over a long time, the origin of glass production in India has not been established beyond doubt. Even so there does not seem to be any doubt that the glass industry in India had made headway in the first quarters of the first millennium B.C., and that the glassmakers were skilful in controlling the temperature of fusion, moulding, annealing, blotching and gold-foiling. The different glass objects found in some 17 sites have been analysed chemically.i The following tables (5.1–5-4) give an insight into the chemical compositions of glass objects found at Taxila, Kopia, Nalanda and Arikamedu.

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*Ceramics*

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Mention has already been made of the Northern Black Polished ware. Bowls, dishes, lids and *handis* (carinated jars) are the general shapes of the N.B.P. ware, sometimes with decoration, which have been found in different

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a Dikshit (M. G.), pp. 43 ff.

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b Wheeler (1), pp. 263–67.

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c Wheeler, Ghosh and Krishna Deva, pp. 96 ff.

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d *Śat. Br.*, XIII, 2.6.8.

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e *Aś.*, 2, 11.35, 13.41, 14.44, 14.60; 3, 3.8; 5, 2.23, etc.

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f *CS. Ci.*, 17, 125.

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g *Hitopadeśa*, 42, 68.

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h *Brh. S.*, 42, 8 and 10.

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i Lal (Dr. B. B.), pp. 17–27.

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TABLE 5.1

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*Chemical analysis of glass specimens (in percentage) from Taxila*a

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| Specimen | SiO₂ | Fe₂O₃ | Al₂O₃ | PbO | SnO₂ | Sb₂O₃ | MnO | Cu | CuO | Cu₂O | CaO | MgO | Na₂O | K₂O | H₂O |
| Red opaque glass .. | 37·09 | 3·16 | | 34·85 | — | Nil | 0·11 | — | — | 7·20 | 6·46 | 0·70 | 10·33 | 0·87 | — |
| White opaque glass .. | 61·32 | 1·70 | | Nil | — | 5·08 | 0·26 | — | — | Nil | 9·74 | 1·64 | 20·26b | | — |
| Thin drawn strips of haematinum | 39·79 | 2·45 | | 38·93 | 0·22 | — | ? | 5·31 | — | — | 2·81 | ? | 10·02 | 0·57 | — |
| Green blue glass tile .. | 70·57 | 1·60 | 2·46 | — | — | — | 0·05 | — | 0·55 | | 4·60 | 2·68 | 14·99 | 2·65 | — |
| Turquoise blue powder of decomposed glass .. | 67·48 | 3·64 | — | — | 2·42 | — | — | — | 3·63 | | 4·92 | 1·80 | 2·48 | 0·55 | 14·15 |
| Fragments of a light green flask .. | 68·34 | 1·20 | 1·67 | — | — | — | 0·34 | — | — | | 8·44 | 1·44 | 17·76 | 0·94 | 0·43 |
| Green blue glass tile .. | 71·01 | 1·84 | 3·74 | — | — | — | 0·05 | — | 0·24 | | 3·73 | 2·32 | 14·99 | 2·65 | — |
| Amethyst glass .. | 58·12 | 1·74 | 8·75 | — | — | — | 0·17 | — | — | | 8·85 | 4·01 | 16·74 | 4·83 | — |
| Brown glass fragments .. | 53·81 | 8·47 | 1·51 | — | — | — | 0·08 | — | — | | 6·27 | 4·50 | 23·52 | 2·35 | — |
| Thin curved fragments of light blue glass .. | 70·69 | 0·81 | 2·88 | — | — | — | 0·01 | — | — | | 7·05 | 0·50 | 12·86 | 4·85 | — |
| Blue glass bangle .. | 68·11 | 2·27 | 2·22 | — | — | — | — | — | 0·44 | | 4·91 | 3·74 | 19·10 | — | — |

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a *AR*, 1921–22, p. 125; 1922–23, p. 158.

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b K₂O 1 per cent.

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TABLE 5.2

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*Chemical analysis of glass specimen (in percentage) from Arikamedu*a

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| Specimen | SiO₂ | Al₂O₃ | Fe₂O₃ | MnO | CaO | MgO | Na₂O | K₂O | FeO |
| Dull blue opaque beads .. | 73·6 | 1·9 | 1·1 | 0·4 | 3·9 | 1·4 | 2·1 | 13·4 | 2·00 |

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a Subrahmanian, pp. 19–20.

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TABLE 5.3

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*Chemical analysis of glass specimens (in percentage) from Kopia*a

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| Specimen | SiO₂ | Sb₂O₃ | PbO | Cr₂O₃ | Al₂O₃ | Fe₂O₃ | MnO | CaO | MgO | CuO | Na₂O | K₂O | H₂O | TiO₂ |
| Small black perforated beads .. | 62·24 | — | — | — | 8·46 | 7·20 | 0·02 | 3·13 | 1·55 | — | 16·70 | — | — | 0·51 |
| Pale yellow beads .. | 70·30 | — | — | — | 5·30 | 1·20 | 0·08 | 2·38 | 1·20 | — | 19·31 | — | — | Tr. |
| Strips of dark blue to black glass .. | 64·80 | — | — | Tr. | 4·90 | 2·95 | 0·06 | 3·71 | 2·10 | Tr. | 21·03 | — | — | 0·45 |
| Green bead with black and coral red decoration .. | 67·13 | — | — | Tr. | 6·70 | 1·50 | 0·03 | 3·03 | 1·60 | — | 19·61 | — | — | 0·40 |
| Fragment of black bangle .. | 66·13 | — | — | — | 7·26 | 0·86 | 0·07 | 2·24 | 1·33 | Tr. | 21·70 | — | — | 0·41 |
| Unperforated spherical beads of clear glass .. | 63·30 | — | — | — | 7·09 | 2·50 | 0·10 | 3·64 | 1·85 | — | 20·52 | — | — | 1·01 |
| Broken pieces of pale yellow-green glass | 66·60 | — | — | — | 6·98 | 1·62 | 0·03 | 2·49 | Tr. | — | 21·70 | — | — | 0·51 |
| Deteriorated glass .. | 60·72 | — | — | — | 10·80 | 0·20 | — | 8·85 | 1·12 | — | 18·30 | — | — | — |

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a Roy and Varshneya, pp. 366–68, 392.

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TABLE 5.4

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*Chemical analysis of glass specimens (in percentage) from Nalanda*a

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| | SiO₂ | Al₂O₃ | Fe₂O₃ | MnO | CaO | MgO | Na₂O | K₂O | FeO | CuO | Cu₂O |
| 1. | 62·61 | 2·05 | 1·61 | 0·06 | 6·95 | 4·17 | 17·85 | 5·04 | — | 0·57 | — |
| 2. | 61·21 | 1·81 | 1·60 | — | 8·15 | 3·83 | 18·25 | 4·98 | — | 0·75 | — |
| 3. | 70·74 | 2·22 | 1·54 | Tr. | 2·11 | 0·26 | 15·80 | 4·98 | — | — | — |
| 4. | 61·50 | 6·13 | 9·82 | — | 5·20 | 0·06 | — | 15·92 | 7·01 | — | 0·49 |

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a *AR*, 1922–23, p. 158; 1930–34, p. 300.

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parts of north India (hence its name)a and also at some places in central as well as southern India. Possibly the N.B.P. ware which, as stated already, appeared first in the region of modern Bihar and eastern Uttar Pradesh might have spread in course of time to some other parts of northern, central and southern India. In north India, they have been found in large numbers in Uttar Pradesh (Ahicchatra, Mathura, Hastinapura, Kausambi, Sarnath, Bhita, Jhusi, Masaon, Sravasti and Atranjikhera); Bihar (Patna, Rajgir, Giriak and Vaisali); Rajasthan (Bairat); Madhya Pradesh (Sanchi, Nagda, Ujjain, Eran, Maheswar and Tripuri); Bengal (Bangarh and Chandraketugarh); Orissa (Sisupalgarh); Maharashtra (Prakash, Bahal, Nasik, Nevasa, Ter and Kaundanyapur); and Andhra Pradesh (Amaravati and Chebrolu). The probable date of the N.B.P. ware spread may be about the sixth century B.C. to second century B.C.

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The N.B.P. ware seems to have been made on a fast-spinning wheel, using fine clay and firing to a high temperature in kilns. It is possible, as

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[Figure: DISTRIBUTION OF PAINTED GREY WARE & NORTHERN BLACK POLISHED WARE 100 0 100 300 500 Km. UDEGRAM TAXILA CHARSADA R. CHENAB R. BEAS R. JHELUM R. RAVI R. SUTLEJ RUPAR HASTINAPUR AHICHCHHATRA TILAURA-KOT R. INDUS PANIPAT DELHI BAIRAT SRAVASTI BANGARH R. BRAHMAPUTRA KANAUJ R. GANGA VAISALI NOH R. CHAMBAL R. YAMUNA RAJGHAT RAJGHIR CHANDRAKETUGARH KARACHI AWRA NAGDA ERAN UJJAIN R. MAHANADI TAMLUK R. IRRAWADDY TRIPURI PRABHASPATAN R. NARMADA MAHESWAR R. TAPTI PRAKASH NAGPUR KAUNDANPUR SISUPALGARH NASIK BAHAL BOMBAY NEVASA TER HYDERABAD R. GODAVARI BAY OF BENGAL BRAHMAPURI R. KRISHNA AMARAVATI CHEBROLU R. PENNAR MADRAS ANDAMAN & NICOBAR ISLANDS R. CAVERY CEYLON ARABIAN SEA NORTHERN BLACK POLISHED WARE } — • PAINTED GREY WARE — △ SITE WITH BOTH TYPES — ▲]

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FIG. 5.7. Map showing the distribution of the Painted Grey and Northern Black Polished wares.

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suggested by some archaeologists, that some of the N.B.P. wares were dressed with haematite before firing, and that the process of firing might be responsible not only for the production of colour ranging from jet black to glossy-grey but also metallic sound, which are the characteristics of this ceramic. The black colour of the ware has been attributed to the presence of ferrous oxide (about 13%)a which would develop (by the action of reducing gases formed in the kiln) on the original highly ferruginous slip which used to be applied to the surface of the ceramic body consisting of a levigated mixture of clay and red ochre. The polishing might have been done before or after the firing. The black polished film of some samples, on chemical analysis, has been found to contain silica 46·55%, ferrous oxide 25·20%, alumina 15·53%, lime 4·74% and magnesia 3·43%. The formation of ferrous silicate may be causative of colouring the body black; and it is not unlikely that the deposition of carbon in the pores of the pottery as a result of the smoky atmosphere of the kiln also plays its role in the black coloration of the pot. There are divergent views on the chemical aspects of the N.B.P. ware. According to the analysis of the archaeological chemist in India, ‘the lustre on the surface of the ware appears to be composed of some easily fusible material, possibly of organic origin, which undergoes incipient fusion at a low heat’.b

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a It is indeed a misnomer to call this ware Northern Black Polished ware, although the archaeologists have been maintaining this nomenclature.

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The chemical analysis carried out at the British Museum Laboratory shows that the unfired pots were dipped in a suspension of ferruginous inorganic material probably resembling a red earth; and that, after firing to a temperature of *c.* 800°C, the kiln was sealed so that the pots cooled in a reducing atmosphere. According to yet another analysis conducted at the Laboratory of the M.S. University of Baroda, the shining black slip might have been produced by an application of a carefully selected liquid clay, ‘peptized’ by the addition of an alkaline material (like *sajji-matti*, *rhe* or *khari*, which is available abundantly in the plains of the Ganga), which interacts chemically with alumina and silica of the clay. On firing, the ware is said to acquire the necessary strength as well as the glaze-like gloss on the surface.c

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The N.B.P. ware specimens found at Taxila, probably belonging to the first or second century A.D., reveal an advanced state of workmanship and sophistication. Well-finished ware with painted lips, handles, spouts, etc., have been discovered. Decorated pottery, though rare, comprises those having painted or neatly impressed designs which include triangles, loops, festoons, common flowers, cocks or peacocks.

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Ceramic ware with utilitarian devices continued to show signs of excellence in the Classical Age as evidenced by terracotta seals, plaques, figurines, bricks and tiles. Apart from the wheel-thrown pottery, the mould-made pots also came into use. Special types of glossy pottery too were produced using mica dust, besides those with graceful and appealing designs which included among others lotuses, certain geometrical forms, spirals and ornate pendants. At Ahicchatra have been observed cylindrical pits of large dimensions which possibly were the special types of kilns for the baking of ornamental pottery and turning of tiles.

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a *AI*, 1946, pp. 55–58.

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b *IAR*, 1955–56, pp. 56–57.

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c Thapar (2), pp. 73–74.

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Copper Statue of Buddha, Sultanganj. (Courtesy, Archaeological Survey of India, New Delhi.) *See p. 299*

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The Iron Pillar at Delhi. (Courtesy, Archaeological Survey of India, New Delhi.) See p. 299

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*Metal-working*

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In the working of metals too India of this period had to its credit spectacular achievements of excellence, particularly in the Classical Age. The metal-workers skilfully worked on copper, bronze, brass and iron. The art of jewellery using precious metals and stones was in a flourishing state. A significant find connected with the jewellery craft has been reported from Ahicchatra. A solid copper bolt (24½" in length and a circumference of 14" at the centre and 12" at the ends), found in the Rampurva Asoka Pillar near Nepal border, reveals an advanced workmanship.a

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In the Classical Age, there were centres well known for the metal industry. Vātsyāyana in his *Kāmasūtra* includes *dhātuvāda* (metal-working) in the list of 64 *kalās*. The Chinese piligrim, Hiuen Tsang, has given a description of how brass was being extensively used in India at the time of his visit, and spoken of a huge copper image of the Buddha (80 ft. in height) and a brass temple being built (height expected to reach 100 ft. or more) by Harsha.b

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A remarkable sculpture of the Classical Age, which sheds light on the copper metal-working of the time, is the huge statue of the Buddha (7 ft. 6 in. in height and nearly a ton in weight), probably belonging to the fifth century a.d. Discovered in the ruins of a Buddhist monastery at Sultanganj (in Bihar) by an engineer of the East India Company in 1864 and now housed in the Museum and Art Gallery of Birmingham, this huge statue appears to have been cast in two layers, the outer layer by the *cire perdue* technique. The inner layer seems to have been cast in segments on a mould composed of sand, clay, charcoal and paddy husks, using iron bands for holding the segments together.c Some Sanskrit texts of this period, viz. *Mānasāra*, *Śilparatna* and *Viṣṇudharmottara*, give an account of the *cire perdue* process.

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Another historic vestige which gives an insight into the admirably qualitative as well as quantitative workmanship of the artisans of the Classical Age is the famous Iron Pillar now located in Meharauli (Delhi) near Qutub Minar.d It has a height of 24 ft. 3 in. (with 1 ft. 8 in. below ground); its diameter diminishes from 16·4″ below to 12·05″ above. The specific gravity of the metal is over 7·5 and the pillar weighs more than six tons. Essentially made of wrought iron, its chemical composition is: iron 99·72%, carbon 0·08%, silicon 0·046%, sulphur 0·006%, phosphorus 0·114% and manganese nil. 'It is not many years since the production of such a pillar would have been an impossibility in the largest foundries of the world, and even now there are comparatively few places where a similar mass of metal could be turned out.’a The probable date of this pillar is about a.d. 400, and since then it has been existing without any rust or signs of decay. The reason for this may be that a thin protective film of magnetic oxide (Fe₃O₄) might have been formed on the surface as a result of treatments given to the surface of the pillar, such as painting with a mixture of different salts, heating and quenching. It is very likely that the rather high phosphorus and the negligible sulphur or manganese content might be the factors causative of the high corrosion resistance of the pillar. In addition to this famed pillar of iron, a colossal iron pillar of bigger dimensions in two pieces and of a later date (about twelfth century a.d.) has been found at Dhar in the Malwa region as will be seen later. These examples illustrate that copper and iron metallurgical practices touched new heights during this period.

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a Neogi (2), p. 18.

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b Majumdar (R. C.), III, p. 588.

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c Neogi (2), pp. 20–21.

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d Neogi (1), pp. 15–21.

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*Copper Metallurgy*

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There has been some recent evidence which gives a glimpse of the possible techniques employed by the early metal-workers for extracting copper from its ores. Obviously the process of winning the metal from

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Fig. 5.8. Schematic representation of a native copper-smelting furnace at Singhara near Khetri in Rajasthan (1831).[^b] (*a*) *Kothi* of three separate annular parts made of fire-clay and placed one upon the other firmly; exterior diam. of each part, 15″; height, 9″-10″; thickness, 3″; quantity of the charge: 2½ maunds (100 lb.) of the ore balls (*piṇḍi*) and 3 maunds (240 lb.) of charcoal along with some iron-bearing material to act as flux; (*b*) chamber for burning some quantity of charcoal to drive out the moisture from the newly-moulded furnace; (*c*) openings for poking the fire from time to time, being closed with moist clay after the poking operation.

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the ore must have been a simple one. A process in vogue even in the last century has been described as follows.c The ore is crushed to a powder on an anvil of stone with a hammer. It is then mixed with cow-dung, made into balls (*piṇḍi*) and roasted. The charge consists of roasted ore, charcoal and iron slag, the last acting as flux smelted for 9–10 hours in a blast furnace made of clay and sand. The slag is first drawn off and the smelted copper which would accumulate at the bottom of the furnace is removed the following day. The mass is again melted, refined in an open furnace using a strong blast from below, and finally cast into bars. By this method the yield of the metal is said to be 2½–7½%. It is very likely that, in ancient times also, a process not altogether different from the above was employed for the extraction of copper from its ores.

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a Ball, III, p. 338.

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b *Gleanings in Science*, **3**, 36, 1831, pp. 380–84, Pl. xxiii.

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c Neogi (2), pp. 63–64; Ball, pp. 239–280.

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*Iron Metallurgy*

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Recent archaeological excavations, especially at Ujjain, have given some clues to the ancient practices concerning iron metallurgy. Probably the smelting operations consisted in heating alternate layers of the ore and charcoal. There is evidence to indicate that calcium compounds were

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FIG. 5.9. Sketch of the remains of a furnace for forging iron objects at Ujjain (period II).ᵃ

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also used in the metallurgical operation possibly as a flux. The charge might have been enclosed with a thick coating of clay so as to form a sort of kiln with passages for blowing in air from below, escape of gases from above and flow of molten mass from the bottom. The molten mass, after cooling, might have been subjected to hammering to drive in carbon and eliminate the slag. The remains of a forge, including the anvil and some iron implements, have also been found in this region.a

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a ᵃ *IAR*, 1957–58, Pl. XLI B.

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Even now in Madhya Pradesh, Bihar and Maharashtra, the primitive methods of smelting the iron ore and forging are in vogue, practised by the *Agarias* and *Khuntia Chokhs*, *Marias* and *Murias* (the tribals of Madhya Pradesh), *Birs*, *Birjhia*, *Agaria Asurs*, etc. (of Bihar), *Gonds*, *Telis* and *Mannewars* (of Maharashtra). The smelting operations are conducted generally in a vertical or slightly tilted cylindrical shaft made of clay about 3 ft. high and 3·8 ft. wide. ‘The shaft tapers to the top and has three openings, a large one at the top, and two (one large and the other small) at the base. The opening at the top is for the introduction of charcoal and iron ores. Often a bamboo platform, called the *machan*, resting on poles and plastered with clay is erected on level with a top of the furnace. This platform is also provided with 3 in. dwarf walls as protective parapets and is sloped towards the opening of the furnace for sliding into it charcoal and iron ore, thus acting as an open hopper. The openings of the bottom are for maintaining the blast and for receiving the bloom and slag respectively. The aperture for receiving the bloom is significantly called the *hagan* or *loha hagora* (aperture for excretion). The wrought iron obtained by hammering the bloom is in the form of lumps or cakes. Bellows are employed for maintaining the flow of air to keep the furnance alive.’ b

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Slight variations have been noticed in different regions in the matter of using the flux and the type of furnace. While the Agarias do not use any flux, the smelters in Naziri Hills (North-West Frontier Provinces) first roast the ore and use limestone in the form of coral reefs as flux. In the Kathiawar area the furnaces are rectangular in cross-section and oblong on plan.

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In south India, the furnaces appeared to be circular on plan and conical in shape. Even as late as in the nineteenth century A.D.,c it was noticed that small furnaces made of red-potter's clay mixed with sand were being used in large numbers by the ironsmiths (in the Salem region) for the production of bar iron. The height of the conically shaped furnaces (diagrammatically shown in figure) was slightly under four feet, the diameter shaping from thirteen inches from below to seven inches at top. The charge, which consisted principally of the common magnetic iron ore and the requisite quantity of charcoal, was introduced from the top. There were two openings at the bottom; one for letting in the blast and the other for taking out the slag. Bellows of goatskin supplied the blast for heating. In about two and half hours the operation would be over yielding lumps of about 50 per cent iron. The lumps, on forging, gave the bar iron of high quality containing a considerable proportion of steel. It is on record that, as regards their quality, the worst of them was as good as the best English iron. The price was still less than that of the market price of the cheapest English bar iron then sold in India. Indian iron was preferred by the British

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a *IAR*, 1957–58, p. 36.

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b Banerjee (N. R.), pp. 182–87.

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c *Public Cousultations* (Campbell), pp. 4160–184.

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[Figure: FIG. 5.10. Possible form of the furnace used by the ironsmiths of south India. (Reproduced from *IJHS*, 1, p. 159)]

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for producing steel of good quality. It is very likely that the crude smelting furnances of the tribals are, probably to a great extent, the direct descendants of the ancient methods of iron manufacture in India.a

Literary Evidence

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As stated earlier, some literary works belonging to this period throw ample light on the chemical practices which were flourishing then. Kauṭilya's *Arthaśāstra*b is indeed a mine of information from the point of view of the history of chemical practices in India. Even though the text does not contain accounts of analysis which would bear scrutiny from the point of view of modern chemical analysis, the observational approach and also the methods of purification, as recorded in the text, are worth noting. There is in this text a section on the examination of precious articles to be received into the treasury. Details are given of the characteristics of pearls and pearl strings, ruby, beryl and other precious substances. ‘Hexagonal, square or round, of pleasant colour, having a suitable form, clear, smooth, heavy and lustrous’ are the characteristics of gems while ‘dull colour, with grains, with a hole in the bottom, broken, badly bored (and) covered with scratches’ are their blemishes as stated in this section.

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a Ball, p. 340.

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b Kangle, pp. 111–50, 176–80.

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In the *Arthaśāstra*, the section on mines and factories deals elaborately with the occurrence and nature of the ores of gold, silver, copper, lead, tin and iron. It is stated that in the case of all ores, when there is increase in heaviness there is increase in metal content. ‘Ore from rocks or a region of the earth, which is heavy, unctuous and soft (and which is) tawny, green, reddish or red (in colour) is copper ore.’ Lead ore is ‘crow-black or of the colour of the dove or yellow pigment or studded with white lines (and) smelling like raw flesh’. Iron ore is ‘grey like saline earth or of the colour of a baked lump of earth’. Obviously, the physical characteristics of the ores were well known. The director of mines was expected to be an expert in the science of metallic veins, exploration of ores, metallurgy and the art of colouring gems. Among the duties of the director of mines was that he should ‘establish factories for copper, lead, tin, *vaikrānta*, brass, steel, bronze, bell metal and iron, and also (establish) trade in metal ware’. Factories and commerce relating to conch-shells, diamonds, gems, pearls, corals and caustics were also contemplated.

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The text also describes in detail the qualities of gold and silver. Gold which is of the colour of ‘lotus filament, soft, lustrous and not producing any type of sound’ is stated to be the best, the reddish yellow-coloured metal of middle quality, and the red-coloured one, of the lowest quality’. If the gold produced from the mines becomes brittle when admixed with lead, it is to be turned into leaves by heating and pounding on wooden anvils. Alternatively it could be processed by infusion with the pulp of the bulbous roots of *kadalī* (*Musa sapientum*) and *vajrā* (*Euphorbia antiquorum*). As regards silver, the text says: ‘that which is white, smooth or soft is the best and the impure silver should be purified with one-fourth part of lead, and (on purification) that in which a crest has appeared at the top, which is clear, lustrous and of the colour of the curd is pure’.

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The artisans of Kauṭilya's time must have been not only skilled in setting (*kṣepaṇa*), stringing (*guṇa*) and making solid or hollow articles of gold but also in the art of mixing the metals in the molten state in correct proportions. In the work of setting jewels in gold, the artisan, according to the text, should use five parts of pure gold, and two parts of gold alloyed with four parts of copper or silver. Silver with a quarter part copper, and gold with a quarter part silver were not considered to be good metals to work with. For the preparation of silver articles, solid or hollow silver could be mixed with half the amount of gold. The *Arthaśāstra* also gives a description of different methods employed for shaping gold and silver articles. As regards minting, the text says that silver coins should be made of four parts of copper, eleven parts of silver and one part of either iron, tin or lead, while copper coins could be made of four parts of silver, eleven parts of copper and one part of iron or any other metal. Undoubtedly, these compositions must have been arrived at by the technicians after a good deal of experimentation, though the text does not contain details in this respect.

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In the *Arthaśāstra* is found an account of fermented juices. 'Sugar-cane juice, jaggery, honey, treacle, the juice of *jambu* (*Eugenia jambolana*) and the juice of jackfruit infused with a decoction of *meṣaśṛṅgi* (*Gymnema sylvestra*) and long pepper, kept for one month, six months or a year and then mixed with *cidbhiṭa* (a kind of melon), *urvāruka* (*Cucumis usitatissimus*), sugar-cane stalk, mango fruit and myrobalan or unmixed (with these) constitute the group of fermented juices.' For purposes of fermentation depending upon the composition of the fermenting mixture, a ferment (*kiṇva*) was also employed. Such a ferment generally consisted of one *droṇa* of the pulp of *māṣa* beans (*Phaseolus radiatus*) raw or cooked, with one-third part of rice grains, *moraṭa* (*Alangium salvifolium*) and the like. The brewers of Kauṭilya's time seem to be well versed in the preparation of several types of intoxicating liquors such as *medaka* (prepared from rice grains), *prasanna* (flour, bark and the fruits of *kramuka*), *āsava* (wood-apple fruit, treacle and honey), *maireya* (jaggery mixed with black pepper powder and decoction of the bark of *meṣaśṛṅgi*) and *madhu* (grape juice). Yet another liquor was *mahāsurā* which was prepared from mango juice with certain essences.

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The *Arthaśāstra* gives a quantitative account of the extraction of oil. 'One-sixth is the amount of oil from linseed, one-fourth from sesame' and the like. The text also has classifications such as sour fruit juices, liquids, spices, vegetables, etc., obviously based on their manifest chemical characteristics.

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An important aspect that should not go unnoticed from the point of view of the Indian alchemy is that in the *Arthaśāstra*, there are descriptions of *rasapāka* and *rasaviddha*. The word *rasa* has been interpreted by some scholars as meaning mercury, and even some attempts have been made to find in these descriptions the earlier chemical practices in India based on mercury. On a deeper analysis, it becomes indeed difficult to justify the meaning of *rasa* as mercury, as probably the former means the smelted (liquid) ore.a The origin of alchemy in India is discussed elsewhere in this chapter.

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Let us now turn our attention to the two medical classics. The *Caraka Saṃhitā*b gives an account of the use of several minerals, metals and metallic compounds, among which the following may be mentioned: *adrija* or *śilājatu* (bitumen), *maṇḍūra* (iron rust), *añjana* (black sulphide of antimony), *suvarṇa* or *kanaka* (gold), *ayas* (iron), *kāṁsya* (bronze or bell-metal), *gandhaka* (sulphur) and *tuttha* (copper sulphate). Classifying the fermented beverages under the title of *madya varga*, Caraka describes beverages under the categories of *madirā* (distilled wine), *madya* (fermented liquor from barley, etc.), *mṛdauka* (from grape juice), *rasāsava* (from sugar-cane juice), *tuṣāmbu* (some fermented liquor from barley gruel), *mādhvīka* (fermented liquor with honey), *āsuta* (brewed mixture containing *soma* plant juice), *akṣaki* (from the chebulic myrobalan), etc. In addition are mentioned nine sources of fermented drinks: cereals, fruits, roots, wood, flowers, stems, leaves, barks and sugar; and from these as many as 84 kinds of *āsava* (wine) could be prepared according to this text.

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a * Kangle, p. 121.

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b * Ray and Gupta, pp. 50 ff.

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*Kāṁsya* (bronze or bell-metal), *loha* (iron), *suvarṇa* (gold), *rajata* (silver), *sīsa* (lead), *tāmra* (copper), *trapu* (tin), *rajata mākṣika* (iron-silver pyrites or marcasite ore), *suvarṇa mākṣika* (iron pyrites of golden brown colour), *srotāñjana* (antimony sulphide), *śilājatu* (bitumen), *tuvari* (alum), etc., are among the metals and minerals, the properties of which are described in the *Suśruta Saṁhitā*. Of particular importance to us, are the details of processes for obtaining different types of alkalisa as well as their use. The term used for alkali is *kṣāra*, and *kṣāra* is among the important chemicals of Indian medicine. Alkalis are classified into three types: mild (*mṛdu*), caustic (*tīkṣṇa*) and those of average strength (*madhyama*). Generally the preparation of alkalis consists in the lixivation of the ashes of certain plants. For this purpose, some 25 plants are mentioned in the *Suśruta Saṁhitā*. The procedure described is as follows: Select pieces (wood, leaves, roots and fruits) of the plants are piled up, a few pieces of limestone kept on them and the whole thing then burnt to ashes. Thirty-two measures of this ash are stirred with six measures of water, and strained through cloth, and the process is repeated 21 times. The extract thus obtained is concentrated by boiling it in a large iron pan. During boiling, it is constantly stirred by means of a ladle till the liquid becomes clear, pungent and soapy to the touch. At this stage the desired quantities (eight measures) each of burnt limestone and conch-shells are heated strongly in an iron pan. The mass is then mixed with three quarters measure of the above-mentioned liquid and evaporated to obtain a solid residue which is then mixed with 64 measures of water and thoroughly boiled, with constant agitation by means of a ladle till a concentrate of the required consistency results. The concentrated solution is now decanted and preserved in closed jars. This is *madhyama kṣāra*.

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If the alkaline extract is boiled to a proper consistency without the addition of the burnt shells, an alkali of mild strength (*mṛdu kṣāra*) is said to result. On the other hand, if the alkaline extract is repeatedly boiled with the ashes of some more plants, the product is stated to be a caustic or strong alkali (*tīkṣṇa kṣāra*). The foregoing descriptions amply illustrate the experimental technique employed and also the nature of quantitative considerations of which the experimentalists were well aware. The method of preparation of *kṣāra* was considered to be an art (*kalā*) and, in fact, it was recognized as one of the 10 important arts of the Āyurveda.

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a *SS. Sū.*, **11.**

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Apart from the triple distinctions made of alkalis with reference to their strength, three other types of alkaline substances have also been mentioned. They are the carbonate of potash (*yavakṣāra*), trona or natron (*sarjikakṣāra*) and borax (*ṭaṅkaṇa*). Hot alkaline solutions were generally used for treating thin sheets of metals like iron, gold or silver before their incorporation into drug compositions. Caustic alkalis also found use for treating surgical instruments which were used for incisions, punctures and scarifications of the diseased parts of the human body. The word *kṣāra* significantly connotes the removal of the unhealthy portions of the body, be it of the skin or flesh.

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Ancient Indians, in particular the physicians, knew a number of salts. The *Suśruta Saṃhitā* mentions the following six types of salts:a (1) nitre (*sauvarcala*, i.e. potassium nitrate); (2) rock salt (*saindhava*, i.e. sodium chloride with potassium chloride); (3) a reddish brown granular salt (*viḍa*), probably consisting of a large part of sodium chloride with traces of sodium sulphate, alumina, magnesia and iron compounds; (4) fossil salt (*audbhida*), probably a saline deposit consisting chiefly of sodium carbonate and magnesium sulphate; (5) sea salt (*sāmudra*, sodium chloride with traces of magnesium salts); and (6) a kind of saline earth (*romaka*).

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A number of acids were also known. The organic acids of citrons, tamarind, pomegranate and of a few other plant products were in use. The earlier texts on medicine do not speak of any mineral acid. In this connection it may be noted that some of the compositions including nitre and alum used by the Indian alchemists for the purification of metals might have constituted the ingredients necessary to give rise to mineral acids in the process, although there is no explicit reference to the mineral acids. The Indian experimentalists did not seem to have any knowledge of the mineral acids in contradistinction to the acids of plant products of which they were quite aware. It may be mentioned that the *Rasa Pradīpa*, an iatro-chemical text probably belonging to the sixteenth century A.D., gives a detailed process for the preparation of a mineral acid called *śaṅkhadrāvaka* (i.e. one which dissolves conch-shells); the *Suvarṇatantra*, an alchemical text possibly of a later date, speaks of *śaṅkhadrāvaka* as a universal solvent, and also refers to its property of dissolving metals. From this it seems that the Indians did not possess the knowledge of the use of mineral acids for dissolving metals before the sixteenth century A.D., though some of the processes employed were in the nature of obtaining solvents of the type of mineral acids.

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The *Bṛhatsaṃhitā* by Varāhamihira is another important literary source which gives detailed information on the preparation and use of fine chemicals like perfumes, scented hair-oils, etc.b Evidently, the chemical techniques relating to them had reached an advanced stage during the time of Varāhamihira. Some of the preparations are worthy of mention. In the chapter on *gandhayukti* (preparation of perfumes) several recipes are given of compounded or delicately blended perfumes. It has been stated that *gandhārṇava* (ocean of perfumes) can be prepared from 16 substances, if every four of them are permuted variously as desired, and in proportions of one, two, three or four parts respectively. *Vālaka*, *spṛkka*, *aguru*, *madanaka*, *dhānya*, *karpūra*, *cola*, *ghana*, *śaileya*, *nāgapuṣpa*, *vyāghranakha*, *nakha*, *tagara*, *karcūra*, *malaya* and *uśīra* are the 16 substances mentioned. Not all these substances have been identified from the modern scientific point of view. Perhaps *vālaka* may be a kind of *andropogan* and *aguru*, a fragrant aloe wood. What is worthy of note is the quantitative approach to blending the perfumes of desired quality. Varāhamihira, in a tabular form, describes how a number of perfumes of high quality can be prepared and says that the number of perfumes resulting from the 16 ingredients mixed in all possible combinations is 174,720.

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a *SS. Sū.*, 46, 111.

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b *Bṛh.S.*, 77, 1–17.

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The *Bṛhatsaṃhitā* gives an account of some adamantine compositions like *vajra-lepa* and *vajra-saṃghāta*.a *Vajra-lepa* consists of extracts of certain types of plants, fruits, seeds, barks, etc. (like unripe ebony fruit, wood-apple), blossoms of silk cotton and *guggulu* (a fragrant gum; exudation of *Amuris agallochum*). The process described is as follows: ‘Boil them in a *droṇa* of water and reduce it to an eighth of its original volume. Mix the residue with *śrīvāsaka* (probably the resin of *Pinus longifolia*), *kundurūka* (exudation of deodar), *guggulu*, linseed, resin of *bilva* fruit, etc., and make it into a paste.’ This glutinous material could be applied on to the roofs and walls of temples and mansions. Its life has been stated to be ten million years. *Vajra-saṃghāta* is a metal-cement consisting of eight parts of lead, two of bell-metal and one of iron rust or brass. It is melted and poured hot as desired.

Pigments

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The remains of ancient paintings at Ajanta (second century B.C. to sixth century A.D.), Bagh (third to fifth centuries A.D.), Badami (sixth century A.D.) and Sittannavasal (seventh to eighth centuries A.D.) give an insight into the use of colours as well as the technique of painting adopted during this period. The principal colours used are *dhāturāga* (red ochre), *haritāla* (yellow ochre: arsenic sulphide), indigo blue, *lapis lazuli* blue, *kajjala* (lamp black; carbon), *khaḍi-māṭi* (chalk white), *geru-māṭi* (*terra verde*) and *jangāl* (green-coloured verdigris). The technique consisted of (i) preparation of the ground in the form of a rough plaster and upon it a fine plaster, and (ii) application of the desired colours on the ground. The rough plaster was generally a ferruginous earth consisting of iron oxide, powdered rock, clay, vegetable, fibres and paddy husk. The plaster was levelled and polished with a trowel or a polishing stone. The fine plaster was one of white lime wash (to a thickness of about 0·1 mm.) applied to the rough plaster when the latter was still wet. The ground was allowed to dry. Animal glue was used so as to serve as the binding medium for the pigments used. The *Viṣṇudharmottara Purāṇa* describes the preparation of the ground for painting in a methodical way.

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a *Bṛh.S.*, 57, 1–8.

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To sum up, the main features of the chemical knowledge and practices in India during the post-Vedic as well as the Classical Age seem to bespeak a concerted and methodical approach. Needless to add that they attracted the attention of the contemporary world. Nevertheless, we are in aridity regarding the theories concerning these practices. And techniques of excellence went ahead of theorizing tendencies. But towards the close of the period under reference, a new way of understanding certain chemical substances and an equally new way of processing them for a purpose that was at once sublime and mystical came on the scene. An esoteric theoretical approach supported by an experimental technique of an entirely different character attracted the attention of a particular section of people who had faith in the ideals and practices of what is known as Tantrism. These constituted the base for alchemy and iatro-chemistry in India.

Cites (16)