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Vedic texts give us unique insights into the development of ancient Indian metallurgy<\/strong><\/p>\n \n Man and metals have an age-old relationship.\u00a0 Different periods of early human Civilization have been named after metals.\u00a0 The attributes of gold influenced the mind and heart of Indians so much so that they conferred upon the supreme spirit the designation of\u00a0hirnyagarbha<\/em>.\u00a0 It was so called, because he remains in a golden egg as an embryo.\u00a0 The two important sources for the History of Indian metallurgy are archaeological excavations and literary evidence.\u00a0 Although a considerable amount of information on this subject from the study of archaeological finds is available, literary evidence has not been studied to the extent it deserves. Unique information related to metals and metallurgy is available in different Sanskrit texts beginning with Vedic texts to medieval and pre-modern texts.\u00a0 There are both direct and indirect types of references.\u00a0 An attempt has been made here to give a glimpse of some such references.<\/p>\n The\u00a0Rigveda<\/em>\u00a0has widely referred to\u00a0hiranya<\/em>, which is the oldest Sanskrit word for gold.\u00a0 It has also mentioned products made from gold, such as water vessel, necklace and visor.\u00a0 Chariots decorated with gold have also been mentioned.\u00a0 The\u00a0Rigveda\u00a0<\/em>(10.75.8) mentioned that the river Sindhu (Indus) contains gold.\u00a0 The word\u00a0hiranyayi<\/em>\u00a0was used for the river.\u00a0 Another\u00a0Rigveda<\/em>\u00a0hymn (8.26.18), states that the path of the river Sindhu contains gold, and the word used for it is\u00a0hiranyavartanih<\/em>.\u00a0 It is interesting to note that Sayana translated this word as\u00a0hiranmayobhayakula<\/em>, i.e. both banks containing gold.\u00a0 The above hymns are some of the earliest indirect references to the alluvial placer gold deposits in India.\u00a0 The river Sindhu was an important source of gold in ancient times.\u00a0 It is interesting to note the references for the availability of alluvial placer gold in the river Sindhu are also reported in modern times.\u00a0 Tucci reported in 1977 that \u201cthere was near the Indus (Sindhu) source, as there are even now, great mines of gold in the region of the Manasarovar and in Thokjalyug\u201d.\u00a0 Further, in the itinerary in\u00a0Khotanese Saka<\/em>\u00a0from Gilgit to Chilas (written between 958 \u2013 972\u00a0 A.D.) the Indus is called\u00a0Ysarnijittaji\u00a0<\/em>—\u00a0 the golden river, which is not a mere poetic attribute, but a reality.<\/p>\n Gold obtained from the river Jambu was called\u00a0jambunanda<\/em>\u00a0and that from the river Ganga was called\u00a0gangeya<\/em>.\u00a0 These were also, alluvial placer gold.\u00a0 The\u00a0Pali<\/em>\u00a0text Anguttara Nikaya narrated the process of the recovery of gold dust or particles from alluvial placer gold deposits in allegorical form.<\/p>\n The\u00a0Mahabharata<\/em>\u00a0referred to\u00a0pipilika<\/em>\u00a0gold (ants\u2019 gold).\u00a0 Heaps of this type of gold was presented to the king Yudhishthira\u00a0 at the time of\u00a0rajasuya yagna<\/em>\u00a0ceremony.\u00a0 Pipilika gold was powdery in nature and of high purity.\u00a0 It was obtained by panning the auriferous soil of ant hills formed by ants or termites as a part of their nature on the land containing placer gold deposits and hence the name ants\u2019 gold.\u00a0\u00a0Kautilya<\/em>\u00a0described a variety of gold called\u00a0rasaviddha<\/em>, which was naturally occurring dissolved gold in liquid form.\u00a0 He stated that one\u00a0pala<\/em>\u00a0(a measure) of this solution converts one hundred\u00a0palas<\/em>\u00a0of silver or copper into gold, which refers to the\u00a0 cementation of gold on the surface of metals like silver and copper.\u00a0 A similar type of dissolved gold know as\u00a0hatakaprabhasa\u00a0<\/em>was mentioned\u00a0 in\u00a0Gandavyuhasutra<\/em>.\u00a0 Kalidas also mentioned such gold solutions and termed it\u00a0Kanaka rasa.\u00a0\u00a0<\/em>It is astonishing to note how people recognized such gold solutions in the past.<\/p>\n Native gold is invariably by no means a pure metal.\u00a0 It contains upto 20 percent silver, copper, iron, lead, bismuth, platinum group metals and other metals, as impurities.\u00a0 Thus, native gold would have different colours depending upon the nature and amount of impurities present.\u00a0 It is logical to assume that the different colours of native gold were a major driving force for the development of gold refining process.\u00a0 Although, evidence of gold refining is available in Vedic texts in an allegory form, it was the\u00a0Arthashastra<\/em>\u00a0of Kautilya, which presented it in detail.<\/p>\n Gold refining was a two-stage process.\u00a0 The first stage was the melting of impure gold alongwith lead, which removed base metal impurities, but not noble metals like silver.\u00a0 The second stage was to heat impure gold sheets with the soil of Sindhu State, which contained salt.\u00a0 The sodium chloride present in the soil reacted with silver and the resulting silver chloride absorbed in the surrounding soil.\u00a0 This was a solid state process, which involved diffusion of silver in impure gold and the subsequent formation of silver chloride at the gold-soil interface.<\/p>\n It is important to note that Kautilya stated that the starting sheet of impure gold must be thin, as this would improve the kinetics of the solid state refining.\u00a0 Usage of gold in granular form, as was the case at least in part in the Sardis refinery of the Lydian kingdom of Anatolia, would result in lower yield.<\/p>\n Another important metal referred to in\u00a0Rigveda<\/em>\u00a0is\u00a0ayas<\/em>.\u00a0 It has a shining appearance.\u00a0\u00a0Ayas<\/em>has different meanings in different periods.\u00a0 In early Vedic period, it means either copper or copper alloys.\u00a0 One of the important products made from\u00a0ayas<\/em>, as stated in the\u00a0Rigveda<\/em>, was the weapon of Indra called\u00a0vajra<\/em>.\u00a0 It was made by the process of sinchan (casting).\u00a0 In the later Vedic period\u00a0ayas\u00a0<\/em>or\u00a0karshnayas<\/em>\u00a0means iron.\u00a0 In the\u00a0Atharvaveda, rajata<\/em>\u00a0(silver),\u00a0trapu<\/em>\u00a0(tin) and\u00a0sisa<\/em>(lead) have been mentioned.<\/p>\n Kautilya also described the method for refining silver, which was similar to the first stage process used in gold refining.\u00a0 Further, Kautilya stated a very\u00a0 interesting qualitative test for ensuring the purity of cast silver ingots. According to it, the surface of the cast pure silver ingots should exhibit an appearance of\u00a0chulika,<\/em>\u00a0i.e., projections similar\u00a0 to cock\u2019s comb.\u00a0 In other words,\u00a0 the top surface of the pure silver ingot has a rising appearance at certain places.\u00a0 In fact, this is a reference to the spitting and sprouting behaviour of silver.\u00a0 Oxygen dissolves readily in molten silver.\u00a0 Molten silver dissolves approximately 20 times its own volume of oxygen near the melting point at one atmosphere pressure of oxygen.\u00a0 Just below the melting point, the solid silver can dissolve oxygen only upto half its own volume under similar conditions.<\/p>\n The large difference in solubility of oxygen in the liquid and solid state causes the evolution of oxygen during solidification of molten silver.\u00a0 Bubbles of oxygen are then given off, resulting in \u201cspitting\u201d at the free surface.\u00a0 As a result, liquid silver from the interior is ejected on the surface of the ingot and a shape similar to a cock\u2019s comb is formed on the top surface after solidification.This author carried out the experimental replication of the formation of\u00a0\u00a0chulika<\/em>\u00a0on a small size cast pure silver.\u00a0 If silver contains base metals such as lead and copper, then the dissolved oxygen would combine with it to form respective oxides.\u00a0 In such a situation, the phenomenon of spitting would not be observed and the surface would be smooth.<\/p>\n In this context, it is interesting to note that the law governing the solubility of gases in metals, known as Sievert\u2019s law, came into existence only in the early 20th\u00a0Century.\u00a0 However, ancient Indians recognized the practical aspect of Sievert\u2019s law in judging the purity of silver.<\/p>\n There is a rich Sanskrit terminology for metals, from which interesting information on history of metallurgy can be derived.\u00a0 Only a few uncommon terms would be cited.\u00a0 Silver has a tendency to tarnish.\u00a0 It tarnishes readily when exposed to atmosphere containing sulphur, and looks blackish.\u00a0 Due to this characteristic, an uncommon Sanskrit name of silver is\u00a0durvarna<\/em>.\u00a0 The copper produced in Nepal was called\u00a0naipalika\u00a0<\/em>or\u00a0nepalaka<\/em>, and\u00a0 was of\u00a0 high purity.\u00a0 Tin recovered from lead-tin\u00a0 alloy was called\u00a0nagaja<\/em>, i.e. \u201cthat obtained from\u00a0naga<\/em>\u00a0(lead)\u201d.\u00a0 Similarly, tin recovered from the impure gold containing tin was called\u00a0svarnaja<\/em>.\u00a0 India was not rich in tin metal.\u00a0 Our ancestors were conscious of this problem and also exploited secondary sources for tin recovery.\u00a0 The presence of lead adversely affects the characteristics of gold and hence, it was also called as\u00a0hemaghna<\/em>.<\/p>\n The\u00a0Rasaratnasamuchchaya\u00a0<\/em>described three types of ferrous materials, viz,\u00a0munda, tiksna<\/em>and\u00a0kanta<\/em>.\u00a0 When iron ore pieces are reduced by charcoal\u00a0 in solid state, iron blocks containing\u00a0 porosity results.\u00a0 For this reason, the reduced iron blocks are also called sponge iron blocks.\u00a0 Any useful products can only be obtained from this material after removing the residual porosity by hot forging.\u00a0 The\u00a0 hot forged sponge iron blocks are also termed as wrought iron.\u00a0\u00a0Munda<\/em>\u00a0was wrought iron.\u00a0 As the name suggests\u00a0tiksna<\/em>\u00a0has superior hardness as compared to\u00a0munda<\/em>.\u00a0\u00a0Tiksna<\/em>\u00a0represented crucible steel made by liquid metallurgy and also probably further carburised wrought iron.\u00a0 Special\u00a0 varieties of iron were called\u00a0kanta<\/em>.\u00a0 An exciting example of wrought iron produced in ancient India is the World famous Delhi Iron Pillar.\u00a0 It was erected in the present position in Delhi in the 5th\u00a0Century AD by king Chandra Varman.\u00a0 However, the engraved Sanskrit inscription suggests that it was probably brought here from elsewhere in the Gupta period.\u00a0 The average composition (wt%) of the\u00a0 wrought iron of the pillar is \u2013 Fe \u2013 0.15 C \u2013 0.05 Si \u2013 0.05 Mn \u2013 0.25 P \u2013 0.005 Ni \u2013 0.03 Cu \u2013 0.02 N.\u00a0 The most significant aspect of the pillar is that there is no sign of any corrosion, in spite of the fact that it has been exposed to the atmosphere for about 1,600 years.<\/p>\n Another striking feature of the pillar is its manufacturing technology.\u00a0 It was made by successive hot forging of directly reduced sponge iron blocks produced from the solid state reduction of iron ore by charcoal, in a die.\u00a0 The joint lines that have not been completely removed by forging are clearly visible on the pillar.\u00a0 This author discussed this aspect in detail and opined that this procedure is basically very similar to current metal powder forging techniques, with a difference that the latter is not usually used to make a long product by joining pieces together (Powder Metallurgy<\/em>, 1990, 33 (2), 119).\u00a0 In both the cases, hot forging in a die is done not only to give the required shape, but also to remove the residual porosity present in the starting material.<\/p>\n Indian crucible steel was a celebrated material worldwide.\u00a0 It was usually produced by simultaneous carburisation and melting of wrought iron in closed crucibles.\u00a0 Valmiki referred to it by the term \u201crefined iron\u201d.\u00a0 Kautilya termed it\u00a0vratta<\/em>, because it was of circular shape.\u00a0 Dr. Helenus Scott sent specimens of a variety of crucible steel, available in Mumbai area, to sir Joseph Banks, the then President of the Royal Society, London, for experimental investigation in 1794.\u00a0 He referred to this steel as\u00a0wootz<\/em>\u00a0in his letter.\u00a0 Recent researches\u00a0 by this author have revealed that the actual name of this steel was the Sanskrit\u00a0utsa<\/em>, which was erroneously transliterated in Roman Script as\u00a0wootz<\/em>\u00a0by Scott.\u00a0 James Stodart, fellow of the Royal Society, did extensive work on this steel and mastered its hot forging, Stodart was so overwhelmed with its quality that he mentioned this name\u00a0utsa<\/em>\u00a0in Devanagari Script on his trade card, alongwith a note that it is to be preferred over the best steel in Europe.\u00a0 It was named utsa because it had a characteristic of oozing out of low melting point liquid phase when heated to moderate temperatures.<\/p>\n Historically brass, an alloy of copper and zinc, was known to man much earlier than they were able to extract zinc from its ore on a large scale.\u00a0 In early period, zinc was designated as\u00a0sattva\u00a0<\/em>of zinc ore.\u00a0 In medieval period, its was designated, as\u00a0yashada<\/em>\u00a0in Sanskrit.\u00a0 Zinc oxide,\u00a0\u00a0 known as\u00a0pushpanjan<\/em>, has been referred to in\u00a0Charak Samhita<\/em>.\u00a0\u00a0Rasaratnakar<\/em>\u00a0(second Century AD) provides the earliest documentary evidence for the cementation process for brass making and reduction-distillation process for zinc extraction.\u00a0\u00a0Rasarnava\u00a0<\/em>and\u00a0Rasaratnasamuchchaya<\/em>described a typical crucible, known as vrintak, having a shape similar to that of a long variety of brinjal, to be used for making the reduction-distillation chamber.\u00a0 The basic principle of the process resembles that of the large scale 12 Century industrial process for zinc extraction uncovered at Zawar near Udaipur.\u00a0 It is a unique discovery and the retorts used at Zawar are similar to the\u00a0vrintak<\/em>\u00a0crucible.<\/p>\n The\u00a0Mahabharata<\/em>\u00a0and some\u00a0Puranas\u00a0<\/em>have referred to ferrous arrowheads, which were subjected to \u2018tailadhauta<\/em>\u2019 treatment.\u00a0 Valmiki used this terminology in the context of battle axe.\u00a0 Some of the commentaries of\u00a0Ramayana<\/em>\u00a0have defined\u00a0tailadhauta<\/em>\u00a0as the process used for hardening (of ferrous objects).\u00a0 Clearly, this terminology was used in the sense of oil quench-hardening of ferrous materials.<\/p>\n Manasollas, written in 1131 AD gives detailed information on fine quality metal image casting by\u00a0madhuchchhishta vidhan<\/em>\u00a0(lost wax process).\u00a0 Both\u00a0sushira<\/em>\u00a0(hollow) and\u00a0ghana<\/em>\u00a0(solid) images were cast.\u00a0 Although the documentary evidence is of a later period, it had been used since a very long time ago.\u00a0 The famous bronze dancing girl from Mohanjodaro\u00a0 was made by this process.\u00a0\u00a0Shilparatna\u00a0<\/em>(later part of 16th\u00a0Century) has mentioned the process of making fine gold powder from thin gold leaves for painting applications.\u00a0 The powder produced would have a flaky shape, which gives higher covering area per unit mass.<\/p>\n In the Indian tradition, people with expertise in technical disciplines were highly regarded.\u00a0 This is reflected in a hymn of\u00a0Atharvaveda<\/em>, in which,\u00a0karmar<\/em>\u00a0(ironsmith or metalsmith in general) has been called\u00a0manishi<\/em>, i.e., a wise\u00a0 or learned person.\u00a0 Further, it has been stated in the\u00a0Kavyamimansa<\/em>\u00a0(10th\u00a0Century A. D.) that goldsmith, ironsmith and similar other people should also be invited by kings in the\u00a0kavya-parik-sa sabha<\/em>, i.e., literary meetings organised to judge the scholarship of poets.<\/p>\n \u092f\u0947 \u0927\u0940\u0935\u093e\u0951\u0928\u094b \u0930\u0925\u0915\u093e\u0952\u0930\u093e\u0903 \u0915\u0952\u0930\u094d\u092e\u093e\u0930\u093e\u0952 \u092f\u0947 \u092e\u0951\u0928\u0940\u0952\u0937\u093f\u0923\u0903\u0951 \u0964 Metal technology, for that matter, all other technologies, are human creations shaped historically by context.\u00a0 The examples discussed here illustrate how ancient Indians solved metallurgical challenges, which helped in the development of Indian metallurgy and also the scientific and technological temper in the people of those times.<\/p>\n It is understandable that most of the metal technologies of the past are not relevant in present times.\u00a0 However, examples from the past can re-energise us towards encouraging local innovations and\u00a0 enterprise at all levels.\u00a0 Finally, it is clear that Vedic and classical Sanskrit texts are knowledge texts, and the study of Sanskrit has value because Sanskrit is not just a classical language, but a vehicle of discovering our knowledge inheritance and assessing its contemporary relevance.<\/p>\n ——————————<\/p>\n * by Dr. R K Dube, retired Professor and Head, Department of Material Science IIT Kanpur. Paper published in Financial Chronicle, Tuesday, April 21, 2015 <\/p><\/div>\n<\/p><\/div>\n <\/p>","protected":false},"excerpt":{"rendered":" Metallurgy Ancient Indian Metallurgy* Vedic texts give us unique insights into the development of ancient Indian metallurgy Man and metals have an age-old relationship.\u00a0 Different periods of early human Civilization have been named after metals.\u00a0 The attributes of gold influenced the mind and heart of Indians so much so that they conferred upon the supreme … Continue reading \u0927\u093e\u0924\u0941 \u0935\u093f\u091c\u094d\u091e\u093e\u0928<\/span>
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