The metal using cultures appeared in the Indian sub-continent around 6th millennium BCE. Subsequently, copper metallurgy is well attested to at various sites by the 4th millennium. Besides copper-bronze, these ancient societies were also aware of various other metals like gold, silver, tin. Even deliberate production of iron goes beyond the 1st millennium BCE. Compared to the great antiquity of these metals, in a historical perspective, regular production of zinc and brass and distillation of zinc is very late.
Zinc is a difficult and enigmatic metal. In the earliest cementation process
finely divided copper fragments were mixed with roasted zinc ore (oxide) and
charcoal (a reducing agent), and heated to 1000°C in a sealed crucible.
The zinc vapour thus formed dissolved into the copper fragments yielding a poor
quality brass, zinc percentage of which could not be easily controlled. Reduction
around 1000°C is crucially important as below 950°C no zinc is produced.
If the temperature was raised above 1083°C, copper melted and flowed down
to the bottom of the crucible. Because of such properties, pure zinc smelting
was mastered so late.
Zinc was largely used in manufacturing brass. It seems that there has been some confusion about early occurrences of zinc, brass and zinc extraction by distillation process. Brass, an alloy of zinc and copper, is known for a long time and can be produced accidentally as has been reported from China and West Asia. In India also there are examples of brass from Lothal and Atranjikhera in 3rd and 2nd Millennia contexts. The ancient Persians attempted to reduce zinc oxide in an open furnace but they failed. In fact zinc distillation was an advanced technique, perhaps derived from Ayurvedic preparations and a long experience of alchemy. Regular zinc production in China began only in 16th Century AD, which was perhaps based on the Indian technique. It required heating the zinc ore in a controlled manner and then condensing the vapours through a retort in a receptacle.
The earliest 14C dates (uncalibrated) for the Zawar mines are PRL 932, 430+100 BCE and BM 2381, 380+ 50 BCE. Old workings at Rajpura-Dariba (375 BCE) and Rampura-Agucha (370 BCE) confirm the mining of lead-zinc ores in the southern Rajasthan during the fifth-fourth centuries BCE onwards.
It has been demonstrated experimentally that brass produced by the cementation process could not contain more than 28 percent zinc. For producing higher zinc content brass, one requires pure zinc to be mixed with copper, which could have been possible only after discovery of zinc as a separate metal and its preparation by a process such as distillation. Though there is considerable amount of literature available on archaeometallurgy, particularly on copper and iron technologies, there is very little literature on zinc, barring few papers by Craddock and his collaborators on zinc and brass. The discovery of zinc distillation was a momentous invention and a remarkable contribution of India in the global history of science and technology. A book on the metallurgy of zinc, brass and zinc distillation in India would, therefore, fill a lacuna in the history of science.
Zawar mines show a continuous development of zinc smelting technology from mid-1st first millennium BCE and finally evolved into the sophisticated distillation process in the twelfth century AD. I propose to study this story of gradual evolution of zinc technology in India. And also how it spread all over the world.
The Vedic literature, for example, Satapatha Brahmana and Atharveda while dealing with immortality speak of gold, which has everlasting lustre and Soma, a plant of exhilarating quality, was also held in high esteem in the society. Such early references to metal are indicative of a long tradition of alchemy in India. According to the Upnishadic doctrine the five elements (earth, water, fire, air and a ubiquitous all pervading principle) give rise to or constitute the human body. The Ayurvedic Samhitas deal with the formation of human body and all related issues e.g., physical processes of digestion, disease and so on. Ayurveda is more concerned about the health and longevity of human body. The Charaka and Shushrut Samhitas deal with vajikarana (increasing virile power) and rasayana (enhancing longevity), for which various compositions and practical procedures have been mentioned. Unlike the principle of alchemy (rasasastra), in which mercury and sulphur play very important role, the Ayurveda speaks about elaborate methods of herbal elixirs, treatment of diseases and surgical practices. The more popular name for brass was riti or ritika; the word was probably derived from harita or yellow, which had been a synonym for gold in the Vedic literature. The word was chosen on account of the yellow colour of gold-like brass. The writings of Manu, Yajnavalkya and Patanjali of the pre-Christian era also refer to bronze (kamsya) and brass (ritika). Both Kautilya's Arthasastra and the earliest Indian brass of Taxila belonged to fourth century BCE, while the earliest 14C date of Zawar Mine is 430+100 BCE. The Arthsastra is the earliest firm literary evidence for the production of metallic zinc on a regular basis in India, which mentions brass as arkuta and liquid ore and refers to burning of a rasa (metal) to produce an eye salve or zinc. The text also records how various metals were obtained for example, tutthodgata (silver) was extracted from tuttha, which was refined 17 times to overcome tuttha. The text reveals that the Directors of Mining and Metal were supposed to examine old mines, locate new ones by examining the physical properties of the ores and establish factories for copper, lead, tin, brass, steel and so on. By the early centuries of the Christian era the Ayurvedic practices were very common in the society.
It seems that the Chinese and Indians considerably shared alchemical knowledge in the Old World as amritadhatu (mercury or the metal of immortality) was often referred to in Mahayana (Buddhist text). In Indian alchemy one finds large number of rasas (minerals) and rasendra (mercury) is called maharasa (king of minerals). They have been classified into maha (superior) and upa (subsidiary) rasas (minerals). The maharasas are known as abhra (mica), vaikranta (kimberlite dust), masika (pyrites), vimala (chalcopyrite), adrija (bitumen), sasyaka (copper sulphate or a compound of copper) and capala (zinc carbonate). Various medicinal plants have been referred to in Rasarnavakalpa, which were used for transmutation and processing of the metal.
In fact a large body of ancient Indian literature refers to various types of metal that were used in different periods. In the epics e.g. Mahabharata and Ramayana, brass and the bell metal have been termed as kamsya, the utensils of which were used for milking and drinking. However, in Grihyasutra brass is called either arakutah, riti or pitala, perhaps indicating different types. Pitala is generally considered to be brass. Among these terms riti seems to be yellow brass, bell metal. According to Gobhila Grihyasutra the Vedic students's hands were supposed to be dipped in bell metal vessels. In Jain literature zinc is known jasada. Since brass has yellow glittering appearance it was also sold as false metal gold. The Ras-Ratnakara of Nagarjuna (a well known chemist of the Satvahana period, fourth century AD), has been referred to as one of the best ancient literary records of brass and metallic zinc (rasaka) production. It also informs about production of brass, cementation process and metallic zinc. The text was probably compiled in its present form in the seventh or eighth century AD. In later periods zinc was also known as yasada, yasadayaka, yasatva.
The Rasaratnasamucchaya, a fourteenth century alchemical text, reveals that the Indian alchemy was not only confined to the principle of mercury and its compounds but also to a large number of other minerals. It reveals names of scores of celebrated alchemists like Nagarjuna, Govinda and others. The rasvidya (alchemy) was kept closely guarded secret and confined to devout practitioners only. It explains how a laboratory should be established in a place that is rich in medicinal herbs and several types of furnaces, instruments, kosthi (for extraction of essences), bellows, retorts etc. The Rasasastra text particularly reveals various kinds of instruments, types of furnace (e.g., dola yantram, kosthi yantram, musa ynatra, adhapatana yantram, svedani yantram, tiryakpatana yantram), and chemical processes used in smelting operations. The tirakpatana yantram (which means distillation by descending) was particularly used for distillation purpose. McNeil writes that this word is so close to the Latin nomenclature that it tempts one to conclude that links existed between European and Indian alchemical workers. It is believed that the ancient Rasasastra (alchemy) developed as Iatro-chemistry during the medieval times when the famous book Rasaratnasamuchchaya was compiled. The Ain-i-Akbari, a medieval text, also refers to ruh-i-tutiya i.e. zinc found at Zawar in Rajasthan. It is quite likely that ruh-i-tutiya may have been derived from the same term tuttha of Arthasastra.
There is thus ample evidence of early Indian literature indicating that a wide range of alchemical practices were prevalent in ancient India. The Rasaratnasamucchaya (14th century) clearly mentions that a particular type of furnace was used for distillation process.
The innovation of distillation technique of zinc in India is a glorious chapter in the global History of Science and Technology. I would like to explore and document the gradual development of Indian alchemy, with particular reference to zinc and brass, which led to the distillation technique, not only in the Zawar area, but al over Rajasthan.
Chapter 1: The first chapter will deal with the characteristics of zinc and brass, its early discovery and use in a global perspective. A short introduction of literary and archaeological records, geographical distribution of ores and mining and smelting techniques will be given.
Chapter 2: It will be devoted to the detailed survey of whole range of Indian literature e.g., Satapatha Brahmana, Atharveda, Upnishads, Ayurvedic samhitas, Ayurvedic medicinal practices, Rasarnavakalpa, Mahabharata and Ramayana, Arthsastra, Buddhist, Jain sources to understand the early beginning of zinc and brass metallurgy and alchemy. Also the alchemical texts e.g., Ras-Ratnakara, Rasaratnasamucchaya and others will be surveyed for zinc production and discovery of distillation technique. Based on the description of the alchemical texts reconstruction of various types of ancient smelting furnaces (e.g., tiryakpatana yantram possibly used for distillation) and other tools will be attempted, to compare them with the archaeological evidence. Besides these, Biblical, Greek and Chinese literary sources (TienKung K'ai-Wu) will also be surveyed for diffusion of the Indian zinc production technique in a historical perspective.
Chapter 3: A detailed survey of zinc and associated minerals including geological information will be dealt with in this chapter. Zinc ore occurs in various regions of South Asia. In western India it is generally associated with either lead or copper bearing deposits. It has been found at various sites in Kashmir and Afghanistan in the northwest; Himanchal Pradesh, Uttaranchal, Arunachal, Meghalaya and Nagaland in the Himalayan region; Uttar Pradesh (in Mirzapur), Madhya Pradesh, Bihar and West Bengal in North India. In South India though Tamil Nadu has only one deposit at Mamanadur, it has been found at various sites in Andhra Pradesh. Western India appears to be the riches zone of this mineral as not only several rich deposit e.g., Ambamata, Kui-Chitrasani, Omlikamala in Banaskantha, Banejnes in the Gir Forest in Junagadh and Vadek-Champaner belt in Baroda and Panchmahals (all in Gujarat) and Zawar, Rajpura-Dariba, Pur-Banera, Deri, Ajmer, Jahazpur, Malikhera-Devpura-South, Dedwas-North Dedwas, Samodi-Tiranga in Eastern lead-zinc zone, Jasma-Rewara-Karor, Kalahudi-Bethumni, Banswara, Ajari, Basantgarh, Pipela-Watera (in Rajasthan) but also ancient mining and smelting has been found.
Chapter 4: Following the survey of Early Indian literature, alchemy and zinc minerals in a pan-Indian context in the previous chapters, we would discuss archaeological evidence of brass, zinc and metallic zinc artifacts to delineate the gradual development and diffusion of technology, leading to zinc distillation process. Zinc vapour fuses with copper easily and this kind of fusion increases the hardness of copper.
Although a very small quantity of zinc has been found from few Harappan copper-bronze artefacts, particularly at Lothal (ranging from 0.15 to 6.04 %) (Nautiyal et al. 1981) and Rojdi (ranging from 0.12 to 1.54 %) we do not know if the Harappans were really aware of the characteristics of zinc. Such small quantity may even be present in the ore before smelting and melting. But at Prakashe, a Chalcolithic site in Deccan, two copper objects each containing 25.86 and 17.75 percent zinc has been found, which is of a very high quantity. Perhaps this was, for the first time, intentionally mixed to harden the objects in early second millennium BCE. Subsequently some early Iron Age sites in the Ganga Valley e.g., Atranjikhera have yielded heavily alloyed copper objects which contain 6.28 to 16.20 % zinc. Therefore it is quite likely that the protohistoric communities were aware of the properties of zinc and brass.
Taxila, located about 20 miles north of Rawalpindi in Pakistan, has yielded few brass objects such as two bangles, one vase and a pot datable to 3rd century BCE to 1st century AD. The vase, which was excavated from Bhir mound at Taxila, contains very high quantity of zinc i.e., 34.34%. This might have been done by mixing pure zinc and copper, which was achieved at Taxila before the arrival of Greeks. There are a large number of artifacts/ sites, datable to the early centuries of the Christian era, which contain high quantity of zinc. To name a few, a part of chariot in submerged Dwarka assays 10.68% zinc ; brass coins of Dhanadeva and Aryavarma of Ayodhya; brass casket of Manikyala (2nd cent AD), scores of icons of Buddha and Brahmanic deities; copper objects of Rajghat containing (17 to 25%) zinc from the early historic context. Falk suggests that a large amount of metal for punch marked coins of silver during the imperial Mauryas was obtained from the Zawar (zinc, lead, copper, silver) mines of Rajasthan. Such a rich repertoire certainly suggests that brass was very popular in the Indian sub-continent during the Mauryan, the Sunga, the Kushana and the Gupta and even in later times.
The Gandhara School of art of the Old World is very well known both for stone and metal sculptures. Various metal sculptures (copper based) of this school contain 5 to 21.7% zinc. Those containing high percentage of zinc may be result of cementation process. Several Brahmanic, Buddhistic icons e.g., Maitreya, Vishnu, Avalokitesvara, Surya, Buddha, Tara, Namasangiti etc., from Kashmir and north Pakistan also have yielded zinc ranging from .01 to 35.14 %. A few Jain and Hindu icons of Mahuli, Gujarat have also yielded zinc as an important component in the icons. The Buddhist bronze images as many as 18, datable to 8th to 12th century AD, of Nalanda contain 8 to 16% zinc. Besides these, a copper object from Timargarh was found contains 12% of zinc. This kind of archaeological evidence certainly suggests that zinc or brass was known to protohistoric communities in certain regions of the Indian subcontinent, though it became popular as early 3rd -4th century BCE when it was valued and prized too. Such long tradition of brass making might have led to the large-scale production of zinc.
The discovery of a roll of sheet zinc at Agora in Athens datable to 2nd-3rd century BCE is an interesting example of pure zinc. The Greeks were not producing such zinc at that time and possibly they obtained it from India. The Indians had certainly mastered the technique of pure zinc and high zinc brass earlier than their counterparts. In Asia Minor the source of brass was at Gordion in Turkey, which is referred to by the Greek writers Theopompus and Strabo as oreichalkos. Perhaps the Greeks, the Etruscans, the Romans, the Egyptians all might have learnt zinc and brass technique around the early centuries of the Christian era from India.
Though few brass objects have been found even in a Neolithic context in China it does not seem to have become common before the 16th century. Zinc smelting began in China in Jiajing period (1552 - 1566 AD) of the Ming dynasty in 16th Century AD, the evidence of which comes from the excavations at Gui-Zhou. It was exported to Europe in the end of the 17th Cent AD under the name totamu or tutenag. Tutenag possibly has its origin in the word Tutthanaga a name of zinc in South Indian languages. A seventeenth century Chinese author has written that Tutenag is a word from some foreign language. Thus there is textual and etymological evidence of transmission of ideas regarding zinc between the two countries. These facts together indicate that zinc was smelted about three centuries earlier in India (in 13 Century AD) than in China and these ideas were transmitted to China in the 16th century AD.
Various communities of the Ganga doab, central India and Bengal e.g., Karmakar, Ure Kumar, Dhokra, Kasera, Khagra, Tamera, Thathreas were involved in pre-industrial traditional craftsmanship of copper, brass and other metals. The Dhokra/Maral, the Khalishahis, the Bhagbanpur, the Ranas of eastern India, the Gharuas of Madhya Pradesh, Jhara in Delhi are traditional artisans and make brass icons of Brahmanic and various local deities. Similarly there are various centers in Karnataka, Andhra Pradesh and Tamilnadu where varied icons of different metals are made. An ethnographic study of the traditional technology would not only enhance our understanding of zinc-brass making but also would help us to understand the diffusion of technology from Zawar, Rajasthan in Western India.
Chapter 5: It will deal with ancient brass and zinc mining and smelting
Among the old workings for zinc, the Zawar complex of Rajasthan in Western India is the most famous. Impressively abundant traces of old workings extend all over the 25 km mining belt and go down to a depth of 90 m below surface. It is claimed that the Zawar miners went up to depths exceeding 150m. The miners perhaps used wooden ladders, scaffolds and launders to drain water in the mines. The wooden samples of two such mines each at Zawar and at Mochina have been dated by 14C. These dates certainly suggest that in the second half of first millennium BCE extensive mining and smelting of lead-zinc ores were done in western India and perhaps the metal was supplied for various regions for coins and other objects. The earliest dates we have for zinc distillation are from a white heap, which is of the 12th century AD.
Zawar (24° 21' N; 73° 41'E), an ancient zinc smelting site, is situated about 40 km south of Udaipur. It was excavated and studied jointly by a team of scholars from British Museum, MS University, Baroda and Hindustan Zinc Limited in early eighties. Zinc smelting was done in small cylindrical retorts (about 30 cm long and 10 cm in diameter) and the vapour was distilled from the charged retorts by placing them in the furnace in a vertically inverted position. The furnaces were found in two parts consisting of a zinc vapour condensation chamber at the bottom and a furnace chamber at the top. These are separated by a perforated terracotta plate measuring 65 X 65 X 20cm. As many as 36 charged retorts were arranged inverted vertically on the perforated plate. From the condensation funnel tubes, luted with retorts, which were inserted through the perforated plate, zinc vapour was collected in vessels in the lower chamber and condensed. Controlling the heat and maintaining constant temperature inside the furnace was perhaps the most difficult job.
Craddock thinks that the Zawar installations were a combination of the principle of mercury smelting and the form of the pottery kiln termed as kosthi type in early Indian literature. Together, they led to one of the most advanced metallurgical operations of the medieval world. The Koshthi furnaces at Zawar were the industrial version of those outlined in the Rasaratna-samuchchaya, with banks of between three and seven furnaces, and each furnace held 36 retorts.
Chapter 6: It will deal with conclusions of the study. Perhaps such a long tradition of Ayurvedic medicinal system, alchemy and traditional technologies prevalent in India resulted in the innovation of zinc distillation process. Despite the very early occurrences of accidentally produced brass in India, China and West Asia, deliberate pure zinc production was very late. The Zawar distillation industry was a unique phenomenon of Rajasthan, in India, which has stolen a march globally in the earliest production of zinc. The innovation of distillation technique of zinc in India is a glorious chapter in the global History of Science and Technology. I would like to explore and document the gradual development of Indian alchemy, with particular reference to zinc and brass, from the mid-1st millennium BCE, which led to the distillation technique, not only in the Zawar area, but all over Rajasthan. The distillation technique of zinc production goes back to the 12th Century AD and possibly reached China from India in the 16th Century. In fact this is an important contribution of India to the world of science.
Thus this study is an attempt to understand the responsible factors behind the invention of zinc distillation technique and to highlight such an important chapter of history of science, which has gone unrecognised.
As I also intend to undertake archaeological and ethnographic field work for first hand data, therefore it seems that to prepare the final draft of the book containing 200 to 250 pages will take about 18 to 20 months to complete.
|2||Early Indian Literature||Vedic Literature; Epics: Mahabharata and Ramayana
Greek, Chinese Sources
|3||Geographical Distribution of ores||Northwestern Region including Pakistan and Afghanistan
Central India including Bihar and West Bengal
Northeastern Region Peninsular region
|4||Zinc- Brass in Archaeological Context||West Asia,
|5||Ancient Zinc Mining and Smelting; Innovation of Distillation Technique||Asia Minor
Zawar and other sites.
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25th February, 2002
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