Ancient Indian metallurgical science
It is of great importance to discuss the subject of ancient Indian metallurgical science. Important and relevant evidences are available on this subject from the Sanskrit based scientific literature and also from the archeological research works. As mentioned in the introduction of this thesis, every artifacts obtained during the archeological excavation, has been evaluated for their periods through the modern carbon dating techniques. Similarly the period of active exploitation of the mines for the minerals and ores was also evaluated through the same technique. Using that data, the date of the mines and metal samples was mentioned in the discussion part of the thesis.
A variety of Sanskrit literature both spiritual and scientific are available for screening the ancient metallurgical knowledge. The information on the literature can be proved correct by the evidences available from thousands of ancient metallic samples of many millennia old collected from various sites.
Vedas give preliminary information on the names of certain metals. Susrutha samhitha, the celebrated Ayurvedic book also contain large amount of data on the metals which are used for the surgical instruments. They also contain information regarding carburisation type of techniques adopted for the metals used for the surgical instruments. Kautilya s Arthasasthra gives great details on a variety of ores for each of the metals known during his period (300 BC). A Buddhist monk Nagarjuna has written Rasaratnakara in 200 AD. It appears from the available literature source that another Buddhist monk with the same name , Nagarjuna has rewritten the book in the 6th century AD. This book contains variety of information on the metals and alloys, including their production and purification. Rasahrudaya and Rasarnava of Govindabhatta, Rasarnavakalpa and Rasendra choodamani of Somadeva,,etc belong to the period 9th to 11th century AD. In fact the study of metals , their alloys and compounds was a part of the rasachikilsa. Hence all the chemical books deal with the subjects of metals and alloys. Bruhath samhitha of Varhamihira is a general book which also describe the metal processing. Even though there exist a few books specifically discussing the metal science like Lohathanthra, they are not available at present in print. However some books and connected research papers appearing on Bharadhavaja s Vymanika thanthra and other instruments give details of a number of artificial metals known as kruthaka loha. Thus in this thesis work, I have gone through these Sanskrit based literature, including the most authoritative Rasaratna samucchaya for collecting data on the metal science.
The literature based knowledge appears to begin from the Vedas. In Rig Veda (1.122.14) a golden ear ring is mentioned as hiranyakarnam manigreevam. A golden necklace is again mentioned in the stanza 1.33.8 as hirnyayena manina srumbamaana. This gives the knowledge of the metal gold as an ornaments. In Sukla yajurveda the following lines give us the knowledge on the metals like gold, iron, lead, tin, silver and carbon steel respectively in the following lines (18.13)
Interestingly each of these metal has different physical and chemical characteristics and need different types of extraction and purification process. The names of these metals give enough proof that their production technology was known. Archeological evidences (given in the later part) support with the period, the above statement on the knowledge of these metals. The ores and metals mentioned in the Vedic texts are also obtained during the excavation from Lothal, Mohan jodaro, Kalibangan, Bhagavanpura, etc. An interesting quotation from Atharva Veda gives a comparison of the colour of the Universal person with that of various metals (11.8.7-8)
His flesh has the colour of iron, blood has the colour of copper, bones have the colour of tin ( or tin oxide - thrapu bhasma) and his odour is that of pushakara (lead)
This comparison indirectly gives the knowledge of the metals and some of their physico chemical characteristics like colour and odour, During a period almost near to that of Vedas. Chandogya Upanishad is one of the earliest Upanishads chronologically coming at par with the Vedas.
An interesting philosophical approach of the metallurgical knowledge is given in Chandogya Upanishad (6.1.6) through one sentence and it conveys a lot about the metals and their processing.
By knowing the nail cutter, all that is related with iron metal can be known...... i.e. Iron is the essence of the tool.
This statement gives us a direct information that when a metal is discussed by its name it is understood that the metal production technology, including the knowledge of ores, metallurgical extraction, purification, temperature connected with all these processing and also the unit operations required to convert the ore into pure metal , was well known
Ancient Indian mines and minerals
Even though proofs have been submitted by Mukherjee 76 on a series of mines utilised for the production of various types of metals during Vedic period, it appears that the earliest description of the mines is given in the Arthasastra written by Koutilya. He has clearly given the duties and privileges of the Director of mines.
The Director of mines is responsible for the handling and proper utilisation of the ores, minerals, chemicals, etc. He should have the knowledge of these materials and their availability. He is responsible for the examination and utilisation of three types of ores classified under bhoomi - prasthara - rasa dhatus. He should know the quality of the ores by means of colour, smell , taste and using the acidic - alkaline textural flavours.
Koutilya focussed mainly the gold, silver lead, tin , coper and zinc ores and metals in his explanations (Arthasasthra 2.6.4) . He has given the correct picture of the utilisation of the resources from the mines as the treasury has its source of income from the mines, from the treasury, the army comes into being, with the treasury and the army, land is obtained. With the treasury is its ornaments, the mines. ( Arthasasthra 2.12.37).
In Arthasasthra the melting process (dravana or vipalana) , solidification process (mruthi)etc., are explained very systematically. Proper heating is required for making the metal alloys says Arthasasthra
As a scientific proof on the metal processing, the carbon dating technique has shown that extraction and purification of the metals like silver, tin, copper, lead, iron and zinc, were undertaken during Koutilyas period (300 BC) and far before that.
Also the best evidences are available for the Sanskrit explanation given by Koutilya on the mines, which can be substantiated by the above techniques. Based on the study reports it could be proved that the Rajpura, Dariba, Udaipur mines in Rajasthan were very active from 1300 BC . The Hatti mines in Karnataka was active from 1000 BC, Ramapura and Agucha mines were exploited for the metals from 700 BC and Zawarmala, Ambamata mines of Rajasthan were actively utilised for the metals from 500 BC. One of the most important observation is that the Kormaranahalli and Tadanhalli mines in Karnataka were yielding iron ores from 1300 BC. The description of iron in Vedas was also due to the fact that mines from Atranjikhera, Pandu - Rajar - Dhibi in Bengal ; Alamghir in Rajasthan and Varanasi in Uttarpradesh were all subjected to a very high level of iron ore production during this period i.e. Also before and during 1200 BC, which is crucial period as far as iron production is concerned.
It is important to search the Sanskrit based information mentioned about the physico chemical characteristics of the ores and minerals of the metals. In Arthasasthra ( 2.12.30) the ores are thus described: The colour of different ores can be yellow, mixed yellowish red, when disintegrated it can have bluish colour, and the colour of green gram, black gram, curd, turmeric, terminelia seeds, liver of animal, spleen, sand, jasmine bud, seed of neem, etc. Some of the ores when heated remain the same and some ejects out smoke and surf.
These descriptions of the ores are perfectly in agreement with the characteristics of the ores of copper, gold, silver, lead and tin .
A series of outstanding descriptions are also given on a variety of minerals and ores of specific metals. The scientific content of these descriptions can be obviously available when those facts are compared with the actual modern knowledge on the subject. The description of the silver ores is given in Artha sasthra:
Native silver ores are of eighteen types. They are classified on the basis of their colour:. the ores having the colour of conch shell, camphor, pearl, jewel, lotus flower, etc., some times the silver ore get mixed with lead and some are white outside and black inside. When heated some of the ores produce smoke. In these ores, the density is directly proportional to the metal content in it.
The copper ores are thus described in the part of Artha sasthra :
The copper ores may have different colours and appearance as: heavy, tawny, green (Chalcopyrite ore) ; dark blue (malachite ore); yellowish tint (azurite ore and pale red (native ore of copper)
This explanation in Arthasasthra agree literally all the qualifications of various types of copper ores given in the parenthesis.
Lead ores are described thus in the book: It is greyish black like kaka mechaka (galena ore of lead), yellow like pigeon bile (gossam ore). (Here too the characteristics agree fully with the descriptions given.)
The tin ores are described in these words by Koutilya:
The tin ores are grey saline or like brown burnt earth (cassiterite ore of tin)
Iron ores are thus described and their modern equivalents are also given:
Iron ores are greasy stone, pale red and having the colour of limonite or of the Sindudrava flower ( haematite ore of iron). The iron ore which has the colour of crow egg or birch leaf is vaikruthaka dhatu ( magnetite ore).
After describing the physico chemical type of characteristics, Koutilya has further mentioned the duties of the Lohadhyaksha. The Lohadhyaksha should establish factories for the production of metals like copper, lead, tin, copper and alloys like vaikruntaka, arakuta, brass , bronze and bell metal . All the business related with the metals should be undertaken by him. Says Artha sasthra:
The subject of metallurgical science inevitably deals with the subject of furnaces, kilns and crucibles used for the production and purification of the metals and alloys. Thus mentioned in Rasaratna samucchaya on the kilns used for the production and purification of the metals:
The equipment used for removing the impurities is known as the Musha/ kiln.
Different types clay is used for the preparation of the kilns. This gives a good information on the ancient Indian background knowledge on the ceramics science.
Yellowish white and heavy sand or reddish white sand that can withstand high temperature for a long time, is the best for the manufacture of the kilns .
Different types of kilns / mushas used for processing a variety of ores and metals are thus described in Rasaratna samucchaya:
Vajra-yoga-vajradravaini-gara-vara-varna-roopya-vida-vruntaka-gostani-malla-pakva-gola-maha-manduka-musala are the names of the common mushas used.
Detailed descriptions are given in the Rasaratna samucchaya on the preparation method and clay composition for the production of the above type of kilns. Different furnaces mentioned are named here based on their sizes, shapes and the purpose they serve.
The temperature for the extraction and purification of a metal is attained according to the nature of the metals and ores. The process by which metals are extracted is sometimes called Kupeepaka vidya. Different types of putas are used for getting specific temperature. All these putas when subjected to the modern tests, are found to provide the temperature between 750 - 900 C. The duration of maintaining the temperature and the dimensions of these putas are given below
Name of the putas dimensions Duration of heat
Mahagajaputa furnace 36" width x depth 150 min
Gajaputa 22 " " 100 min
Varahaputa 16" " " 50 min
Kukkutaputa 9" " " 5 min
Kapota puta On the surface of the earth low temperature
The above time duration was experimentally proved using the modern instruments after making the putas by following the details given in the above mentioned book on the dimensions 77
The above types of putas were made using cubical arrangement of cow dung cakes. For example in mahagajauta, 2000 cow dung cakes were used and in other putas 1000, 800, 40 and 8 cakes , respectively were used.
From this it is clear that there existed a standard set up for the furnaces. Metallurgical process were not adopted as a crude heating procedure. Every puta has a definite specification to follow.
Qualification of pure metals are described in Rasarnava ( 52 -55). The purity of the metal flowing out of the furnace can be judged using these physical parameters.
Pure metal is the one which when melted in crucibles, does not give sparks, bubbles, spurts, lines or scum on the surface. The molten metal which does not produce any sound and is tranquil like gem flows out from the furnace.
The above explanation given agree well with the qualifications on the purity of the samples obtained during archeological studies. The purity of the metal was assayed using modern instruments and found to have the following composition
Name of metal and alloys Place from where obtained % Purity
Copper Nalanda 97.9
Copper Mohenjodaro 97.1
Copper Atanjikhere 97.3
Copper Harappa 98.8
Copper (ii) Harappa 99.0
Silver Mohan jodaro 94.5
Lead Mohan jodaro 99.7
Bronze Takshasila 85.0 % Cu + 9.8 % Sn
Brass Takshasila 55.4% Cu + 34.3% Zn
These metal and alloy samples were produced during a period ranging between 3000 BC - 200 BC
Thus archeological evidences submit absolute proofs for the metallurgical capabilities explained in the Sanskrit literature.
Corrosion of metals: Degradation of metals by way of the reaction with oxygen, moisture, acidic and alkaline materials present in the atmospheric air is a natural phenomena. This is termed as corrosion in modern science. The concept connected with the corrosion and the degradation of metals is clearly mentioned in Rasarnava (7. 89, 90)
Gold, silver, copper, iron, lead and tin are the six types of metals which undergo self degradation at a slower rate in the reverse order of this arrangement. ( the statement means in the reverse order of the arrangement the metals are more and more stable)
I.e. Gold is the least (slowest) corroding and the tin is the fastest corroding metal and the rate of corrosion increases in the order steadily.
Yajnavalkhya smruthi refers to the cleaning of the metals in the Acharadhyaya 78
Tin, lead and copper may be cleaned with alkali and acids. Iron , bronze and copper alloys are cleaned with ash and water.
The rationale being this is that the use of acids and alkalies rapidly decompose and dissolve the corroded impurities accumulated on the surface of the metals and cleanse the surface.
Alloy making: The ancient Indian authoritative knowledge on the production of the alloys has been well appreciated from time immemorial. A number of examples are available from different parts of India for demonstrating the authority on the metallic alloy production. Arthasasthra says that the coins are manufactured using different metals, by alloying. The Director of coins Lakshanadhyaksha has the responsibility of making coins with different denomination as given below:
The Director of coins should know how to make four types of coins: i.e. Coins of one pana, half a pana, one fourth of a pana and one eighth of a pana using copper, silver , lead, iron and if required other metals.
This descriptions gives the scientific way of alloying the metals known during the period of Koutilya. The following statement if further explained with the help of commentaries:
The above statement means; padajeevana type of coins contains 4 parts of silver and 11 parts of copper and 1 part of any other metals like iron, tin, lead, or antimony. This coin is known as Mashakam. Half of this composition known as ardha mashakam, one fourth of this, gives a coin known as kakani, one eight of one pana is ardha kakani.
This gives an upto date type of knowledge of alloy making process for the production of coins, which is one of the sophisticated techniques adopted for getting uniform size, shape, weight and quality for coins
Bronze: Bronze was one of the most commonly used alloy in ancient India. Archeological information available on the bronze is plenty. Bronze and brass are the two alloys obtained from almost all the excavated sites, in India. This shows that, the processes of preparation of bronze was familiar through out this continent. Temples in south India have many bronze and brass statues , idols, big vessels and other items.
Panini s Ashtadhyayee ( 8.2.3.1) gives the information on brass and bronze vessels.
Brass and bronze vessels can be used for storing ghee, milk, etc.
Panini was a contemporary scholar of the ruler Pushyamitra Sunga (187 BC). Rasaratna samucchaya (5.205) gives the composition of one type of bronze as:
Eight part by weight of copper and two parts by weight of tin give the bronze.
Archeological studies support this description , as many bronze samples contained 10 -20 % tin alloyed with copper.
Brass: The Indian technology of brass production is as old as that of bronze. The metal, zinc was called suvarnakara because it converts copper into gold like alloy. Two methods were followed in India for the production of brass. First method, by directly alloying the copper and zinc and the second is by alloying copper with zinc minerals, like calamine. Rasaratnakara (3) gives this explanation:
What wonder is that calamine ( zinc ore) roasted thrice with copper convert the latter into gold ( gold coloured alloy - brass)
The procedure explained here is the direct alloying of copper with zinc ore. Zinc metal from the calamine ore alloys with copper to give brass. Modern metallurgical studies have shown that the maximum content of zinc which can alloy to form the brass, from zinc ore is 29%.
Majority of the brass samples obtained during archeological excavation contained less that 28% zinc. This proves the common procedure adopted in ancient India was as given in the above Sanskrit lines, alloying by hating copper with calamine (zinc) ore.
Rasarnva (7.34 -38) gives thus on the brass alloy formation:
Zinc, a metal like tin converts copper into gold.
This line is partly repetition of that from Rasaratnakara . Hence the word gold is to be interpreted as gold like
Panini in Ashtadhyayi (5.1.30) has mentioned the word Suvarnakara for tin/zinc while discussing the coins made of copper by alloying with tin / zinc.
Brass samples obtained from Lothal contained 6.04% zinc and 70 % copper. This belongs to the period of 2200 BC. Earliest brass sample obtained, containing more than 28% zinc, was from Takshasila (4th century BC). Obviously, here the zinc metal was alloyed directly with copper, since the zinc content in the alloy was above 29%. Rasaratna samucchaya ( 5.191 -193) gives the description of brass as follows
Brass is of two kinds which are known as reetika and kakatundi. The former when heated and plunged into sour rice gruel turns into copper colour and the latter turns black by the above treatment. The former is heavy, soft, yellow, resistant to hammering, brilliant and smooth.
This explanation stands scientific as far as the qualifications of alpha and beta types of brass are concerned. The brass which contains less than 28% zinc has all the above said property and it is known as alpha brass, where as the second one is beta brass that contains above 28% zinc in it.
Bell metal: The qualification required for the bell metal alloy is different from those of other types of alloys. It should give a perfect, melodious and attractive sound. The bell metal alloy is mentioned in Arthasasthra. Method for separating copper from bell metal is described in Rasaratna samucchaya (8.37)
Molten bell metal is heated with a little tala or orpiment, blown with a bent tube and freed from Ranga of tin and what we get is the copper separated from bell metal . (Ghoshakrushtam thaamram means the copper extracted from bell metal). This copper may contain traces of other metal components also, hence may have special grade and quality.
Panchaloha: Panchaloha is the most common alloy used in making idols in temples for the last few thousand years. Sanskrit and regional language literature give detailed description on the panchaloha vigrahas. Charka samhitha gives this explanation (1.70)
In pancha loha , gold and separately copper, silver, tin, lead and iron are alloyed.
In Rasaratna samucchaya (5.212) panchaloha alloy is separately described as follows:
An alloy of five metals of tin, copper , brass , iron and lead is called panchaloha.
Metal seal:
Bruhath samhitha of Varahamihira (57 -1.7) gives the explanation of a metal seal known as Vajrasanghatha.
An alloy of eight parts lead, two parts bell metal and one part brass has been described by Maya as the vajra sanghatha metal seal.
Pure metals:
Copper: Yajurveda mentions about copper, in the name thamra. Copper metallurgy has got a long tradition in India. Mehargarh excavation has shown that the copper samples obtained from there belonged to 8000 BC. One of the many samples obtained from this site recorded the production period which can be around 7786 +/- 120 BC. More than 2500 copper samples could be excavated from different archeological sites.
As far as the Sanskrit literature is concerned, it appears that Arthasasthra comes first in the description of copper, other than Vedas. The earlier mentioned are the descriptions of copper ore and various alloys made of copper. The purity of copper metal obtained from Harappa was 99% and that obtained from Mohen jodaro was 97 %. Ancient copper technology should have been good to get this level of purity for the copper metal.
Iron: There are evidences available from Mesopotamia, Egypt and Afghanistan on the efforts taken in the production of iron during 3000 - 2000 BC. Similar trials were also conducted in Cyprus during 1600 BC 80 . Historical data proves that upto 1600 BC, none including Greeks and the Mediterranean people could produce iron. After putting all the evidences together, it can be concluded that till 1200 BC, iron production was not conducted succesfully anywhere in the world, other than in India. Yajurveda mentions about iron as syamam and also loham. In Susrutha samhitha and Charka samhitha, the use of iron based drugs for treating the anemia as an asavam is mentioned. This asavam is known as Loha asavam:
For years together, the iron nails are treated/stored in ghee and that ghee is used for the preparation of iron asavam.
Archeological evidences show that iron was commonly produced in five regions in North India during or prior to 1200 BC. An iron sample obtained from Ahar was dated during 1300 BC. Rasaratna samucchaya gives defintion and explanation for the three types of iron ( Rasaratna samucchaya 69)
Three important classes of iron are Munda loha ( cast iron), Teekshana loha (carbon steel) and Kanta loha (soft iron).Further classification can be seen in the explanation of each of the above type of iron The Munda loha is of three kinds; mrudu, kunda and kadra.
Theekshna loha is of six types. Khara, sara, hrunnala, trivrutta, vajra and kala
Kanta loha is of five classes which are bhramaka, chumpaka, karshaka, dravaka and romaka.
It is an interesting information to note that the above classes and subclasses are well defined in modern science, with physico chemical characteristics of the product.
In Rasaratna samucchaya, the qualities of roasted iron (which is iron oxide) and the rust of iron ( it is also the iron oxide) are compared (148)
The qualities of the air roasted iron and the rust of iron are the same. Therefore the latter was also acceptable for medicinal purposes.
Carburisation is a process of hardening the iron which is achieved by inducing more carbon in the metal by heating. This method is of special use in hardening and sharpening the iron tools like swords. Bruhath samhitha (50.26) explains the method of carburisation of iron.
The iron weapons treated with a day old solution made of the burnt powder of bananas, mixed with butter milk and then sharpened properly, will not break in stones, nor become blunt on other instruments.
Carburised iron weapons were spotted in many places by the archeological study groups. The process of carburisation has been discussed in detail by Bhatia 80 b . The quality of Indian steel has been referred to by Ktesias who was in the court of Persia in the 5th century BC. Swords made in India were purchased by Persian kings. Alexander the Great was said to have received 30 pounds of Indian steel in 326 BC, from King Porus for making Damascus swords.
The above information are important historical evidences on the capability of iron metallurgy in India and also the quality of the metal produced here. They also support the scientific explanation given in the Sanskrit literature.
Silver: Silver metallurgy was known to Indians at least from the period of Mohanjo daro civilisation. A variety of silver articles was obtained from there. Arthasasthra describes silver as follows (2.13.31)
Silver has the colour of jasmine bud. It contains a lot of lead, it may have the colour of sky, it is white, soft and also precious. When mixed with 4 parts of lead, the alloy will have the colour of fresh curd.
Artha sastra describes the purification method of silver as a continuation of the above lines:
The impure silver is mixed with bone powder, 4 parts lead, 4 parts sand, 4 times cow dung, 3 parts kopal together 17 parts. This mixture is taken in a kiln, mixed with salt and sand and melted. The pure silver gets separated in the pure form. If mixed with some gold, it adds to the lustre of silver.
The above two explanations fully agree with the scientific observations on silver metallurgy and charecteristics. In fact this is the actual process adopted for the removal of impurities such as lead, iron,etc from the silver during its extraction process.
Qualifications of silver are further explained in Artha sasthra ( 2:14:33)
If silver is mixed with lead, it gives an alloy with a bad smell. The alloy will be rough, less coloured and less shining in appearance.
This silver has to be purified with the bone powder in a furnace ( if lead is to be removed)
This concept explained is practised in the modern cupellation process also, for the purification of silver. Instead of the calcium and phosphorous present in the bones, calcium phosphate lining is directly given in the crucibles, known as cupels , in the modern process. Detailed description of other silver alloys is given in Artha sasthra ( 1.13.31)
An alloy of 3 parts of copper and 28 parts of silver has the colour swetha lohita. The alloy with 3 parts of gold and 28 parts of silver has a colour peetha raga.; two parts of silver and one part of gold give an alloy with green gram colour . Two parts of silver, one part of gold and 1/6 iron give black coloured alloy which when mixed with mercury gives silver with a colour of golden bird s feather.
These descriptions give us full information on the technology adopted for making different types of silver alloys and also their physical characteristics. The description continues and some more varieties of silver alloys are mentioned:
The alloy of two parts of silver and one part of copper is known triputakam; one part of iron and one part of silver is known as vellakam; one part each of iron, silver and gold is known as vellakapasaritham. One part each of copper and gold is known as hemapasaritham.
Almost all these types of alloys could be located from various archeological centres during excavation studies. One sample of the silver alloy obtained from Mohan jodaro had a silver content 94.5%. Rasarnava (12.42.2) gives the colour of silver- gold alloy
Twenty five percent gold with silver will have the colour of pure gold.
Rasarnava (12.49.2) says that for sales purposes the above alloy can be further mixed with silver..
Thus the literature descriptions and the practical observations on silver are scientifically agree to the highest level of accuracy.
Mercury: Mercury is a liquid metal which is described in all the Rasachikitsa books written in Sanskrit. Charaka samhitha and Susrutha samhitha give detailed description on mercury and many of its physico chemical characteristics including some of the compounds like oxide, sulphide, sulphate, etc.
Rasaratnakara (37) gives this explanation on the distillation process of mercury extraction
The mercury ore (known as darada ) when distilled in a distillation set up gives drops ( of mercury ) with the help of water (when condensed the vapour with water)
This is also the modern procedure adopted for the separation of mercury from its ores like calamine. In Rasaratna samucchaya (8.64) the following description is given
When the refined ore of mercury is heated in a distillation set up, the vapours move up, down and sides. When condensed with water, it gives drops of mercury which can be collected . This mercury when reacted with tin, a solid amalgam is formed.
Rasaratna samucchaya ( 3.141,144) describes the mercury distillation process
When the mercury ore is distilled and the vapours are condensed, it gives the mercury known as suta. ( this explanation is also application for zinc)
Lead: Rasaratna samucchaya (5.171) gives this definition for the metal lead:
Readily fusible, very heavy, having a black and white appearance on fracture having off foetida odour and black on the outside surface is the lead.
This gives an absolute characteristics of the metal lead. The purity of lead obtained from ancient sites of Mohan jodaro was 99.7%. This is a proof on the quality of the lead production technology existed here . As mentioned earlier, the lead was used for making the metal seal known as vajra sanghath an alloy containing lead as an important component. (Bruhath samhitha 57.1.7). Rasaratna samucchaya gives one of the applications of lead ore as a hair dye (3.146)
Hingularda or cinnabar was known to occur in two varieties; inferior and superior grades, The ore coming from Gurjar province near the Abida mountains, coloured yellow with lamella, can be used for preparing hair tonics or dyes.
Zinc: Zinc is an ash coloured low melting metal. It has been described in this thesis under the alloy brass. The detailed description of the production of zinc metal is given in Rasaratna samucchaya.
Brinjal shaped crucible is attached with a 12 angula long tube over it like an inverted flower of dhatura. A hole of 8 angula diameter is made in the tube. This crucible is used for the
zinc distillation (Rasaratna samucchaya 10.22,23)
A series of brinjal shaped crucibles, set up in series as rows, were found during the excavation of zinc producing sites in Rajasthan. Dozens of crucibles thus arranged in 6 x 6 sets, used during 1500 BC or before, could be located from these sites.
In Rasaratnakara (31,32) the flow of zinc metal from the distillation set up is thus described:
There is no doubt that this process yields an essence of metal (zinc) of the appearance of tin, from the crucible known as mooka musha.
Crude tin resembles the zinc metal. Biswas 82 has given a detailed description on the metallurgical process of ancient Indian technology on zinc production. He has concluded here that the brass containing 36% zinc, was produced in India directly by alloying zinc and copper. The brass samples containing 46% zinc is brittle and those containing 36 - 46% zinc were of medium texture. This type of products were also obtained during the excavation. Some of the brass samples of the Vedic period belonged to alpha and beta types.
A zinc sheet was excavated from Agora, a town in Athens, Greece. It has been proved that this sheet was produced in Takshasila in the 3rd century BC.
A number of historical and archeological evidences support that the zinc production in India started many millennia ago. This technology was smuggled to the West , first in 1597 AD, by a metal smith Libavius 83 . In 1616 AD, the name Zinc was given to this metal by Parcelius. ( till then this metal was known in West as Malabar lead). Later on, William Champion, a metal smith from Warmeley, UK. who collected the details of the metallurgical process from Rajasthan, applied for the patent in UK. It is said that a person by name Dr.Lane visited Rajasthan for collecting the details of the zinc extraction process84 and the technology was spread from there. Thus Indian technology on the production of zinc metal got directly and indirectly transferred to the West, during the 16th and 17th century AD
Tin: The metal tin has been discussed in detail in almost all the Sanskrit Rasathanthra books. Rasaratna samucchaya ( 5. 153, 154) describes, in detail the qualifications of alpha and beta type of tin.
There are two types of tin known as khuraka and misraka. Khurakam is the superior quality tin and the misraka is the subordinate one. Khurakam type of tin is white , soft, flexible, tooth coloured, dense, without making the metallic sound which is beta tin and the mixed black and white coloured one is the misraka, the alpha tin.
Rasopanishad gives a detailed description on production, purification and alloy making with tin metal. The full chapter description on tin can be seen in Vangasthambhana sodhana adhyaya of the Rasopanishad. Rasarnava (7.112) gives the process for the purification of tin metal
By putting powdered bones of buffalo in the crude molten tin metal and sprinkling its urine, the tin can be produced and purified from its ores.
The bone powder acts as the source of calcium for the tin purification by acting as the flux in the removal of the impurities. The phosphorus present in the bone reacts with atmospheric oxygen to form phosphorous oxide and in presence of water, the phosphoric acid is formed, which purifies the tin.
The modern technology for the production of tin came to be known in Europe only in the 16th century AD through a metallurgist Agricola 85 where as in India the metallurgy of tin has a history of thousands of years. The metal is also mentioned in Yajurveda as thrapu.
Vijay Deshpande 86 has conducted detailed studies on the ancient Indian technologies on tin. Particularly the details given in the Rasopanishad and proved that all the descriptions are scientifically true. He prepared a variety of tin alloys by following the descriptions given in Rasopanishads. One alloy of tin giving a marvellous appearance is described in Rasaratna samucchaya (20 -2)
Tin with mica and equal quantity of gold are placed in a closed crucible along with a plant product known as vimala and roasted. It is accomplished in a koorpathootha to get an alloy of metal resembling emerald in colour and lustre.
Dr. Pandy has proved the quality of the alloy by producing the same. Many similar explanations are available in the Sanskrit literature on tin based alloys . A variety of tin alloys were also excavated from the archeological sites. A few examples are given with bronze alloys.
Gold: Gold is a metal well known to Indians for many millennia. It is mentioned as a synonym for the wealth and property in Vedas. Gold purification has been explained in Arthassthra (2.13.31)
Different types of gold having various colours mixed with lead and converted into metal sheets, mixed with cow dung cakes, sand of Sourashtra and salt. This is then heated strongly to get the best coloured gold, in bluish white, greenish, dove coloured, etc
Many alloys of gold for coin making are described earlier in this chapter. One such alloy referred to is given in Bharadhvaja s Amsubhodini 87 .that alloy is prepared as follows:
Eight part of potassium iodide, 16 parts of copper of chuleethamra grade (one out of 16 grades available) , 8 parts of gold namely hiranyaka grade, ( one out of 12 grades of gold known). 6 parts of arsenic sulphide, 5 parts of mercury, 6 parts of quarts are heated in a crucible of tortoise shape and melted at 432 temperature and then poured the molten alloy into the mould.
This alloy was prepared by prof. Dongre 87 and proved the descriptions are well in agreement with the facts mentioned.
Thus Sanskrit literature carry a lot of information on the subject of metals and alloys. Many of these alloys and some of these methods might not even have come to the notice of the modern scientists. Hence it is worth while to peruse into the subject by which one can fetch better or more useful information on metals and their alloys
CONCLUSION
There were hundreds of books written in Sanskrit discussing the subjects of mathematics, astronomy and metallurgy, which are the original contributions of ancient Indian scientists
Hundreds of commentaries were written in Sanskrit and in other languages which also contained original contributions other than detailed explanations of the methods, process and data of the original book.
Many books, data and technology were transported/smuggled/taken/donated to foreign countries during or before or after the renaissance period, in the West.
Many of these books were translated in foreign languages by scholars. Original books and their translated versions have also spread to different countries.
During the renaissance period many European scholars studied these books and brought into light the original scientific content in them. Some of these knowledge have been utilised by the Europeans and others. Some of them were claimed by the foreigners .
In these books information on almost all the aspects of the modern mathematics are given. These contributions start from the number system to the most complex geometrical parameters and theorems.
Many of these discoveries are original contribution of Indians which are at present known in the names of the Europeans or Western scholars. Many more theorems are still unknown to the world of mathematics even now.
The Indian concept of astronomy and geography is perfect modern knowledge, which are at par with the latest observations.
Many details available in the modern astronomical books are also available in the ancient Indian astronomical books, some which may need more refinement.
Some of the latest views on modern astronomy perfectly agree with the knowledge that is thousands of years old, which originated in India.
Much of this knowledge has been obtained as a result of the original experiments and studies conducted by ancient Indian scientists.
A variety of instruments have been explained for the determination of the astronomical data. They were all arrived at based on the scientific observations. In many cases only the conclusions are given in the Sanskrit books.
Detailed observations and scientific data are presented against the superstitions mentioned as the stories in the Puranic texts.
As far as the metallurgical part of the thesis is concerned , data available shows that mines, minerals, metals, ores, etc, are described in detail , in Sanskrit literature. These descriptions are substantiated by the archeological observations.
The solid proof of the metallurgical capability available are from the archeological sources of these metals and alloys from various sites spread over this nation.
Ancient indian metallurgical science ebook
It is of great importance to discuss the subject of ancient Indian metallurgical science. Important and relevant evidences are available on this subject from the Sanskrit based scientific literature and also from the archeological research works. As mentioned in the introduction of this thesis, every artifacts obtained during the archeological excavation, has been evaluated for their periods through the modern carbon dating techniques. Similarly the period of active exploitation of the mines for the minerals and ores was also evaluated through the same technique. Using that data, the date of the mines and metal samples was mentioned in the discussion part of the thesis.
A variety of Sanskrit literature both spiritual and scientific are available for screening the ancient metallurgical knowledge. The information on the literature can be proved correct by the evidences available from thousands of ancient metallic samples of many millennia old collected from various sites.
Vedas give preliminary information on the names of certain metals. Susrutha samhitha, the celebrated Ayurvedic book also contain large amount of data on the metals which are used for the surgical instruments. They also contain information regarding carburisation type of techniques adopted for the metals used for the surgical instruments. Kautilya s Arthasasthra gives great details on a variety of ores for each of the metals known during his period (300 BC). A Buddhist monk Nagarjuna has written Rasaratnakara in 200 AD. It appears from the available literature source that another Buddhist monk with the same name , Nagarjuna has rewritten the book in the 6th century AD. This book contains variety of information on the metals and alloys, including their production and purification. Rasahrudaya and Rasarnava of Govindabhatta, Rasarnavakalpa and Rasendra choodamani of Somadeva,,etc belong to the period 9th to 11th century AD. In fact the study of metals , their alloys and compounds was a part of the rasachikilsa. Hence all the chemical books deal with the subjects of metals and alloys. Bruhath samhitha of Varhamihira is a general book which also describe the metal processing. Even though there exist a few books specifically discussing the metal science like Lohathanthra, they are not available at present in print. However some books and connected research papers appearing on Bharadhavaja s Vymanika thanthra and other instruments give details of a number of artificial metals known as kruthaka loha. Thus in this thesis work, I have gone through these Sanskrit based literature, including the most authoritative Rasaratna samucchaya for collecting data on the metal science.
The literature based knowledge appears to begin from the Vedas. In Rig Veda (1.122.14) a golden ear ring is mentioned as hiranyakarnam manigreevam. A golden necklace is again mentioned in the stanza 1.33.8 as hirnyayena manina srumbamaana. This gives the knowledge of the metal gold as an ornaments. In Sukla yajurveda the following lines give us the knowledge on the metals like gold, iron, lead, tin, silver and carbon steel respectively in the following lines (18.13)
Interestingly each of these metal has different physical and chemical characteristics and need different types of extraction and purification process. The names of these metals give enough proof that their production technology was known. Archeological evidences (given in the later part) support with the period, the above statement on the knowledge of these metals. The ores and metals mentioned in the Vedic texts are also obtained during the excavation from Lothal, Mohan jodaro, Kalibangan, Bhagavanpura, etc. An interesting quotation from Atharva Veda gives a comparison of the colour of the Universal person with that of various metals (11.8.7-8)
His flesh has the colour of iron, blood has the colour of copper, bones have the colour of tin ( or tin oxide - thrapu bhasma) and his odour is that of pushakara (lead)
This comparison indirectly gives the knowledge of the metals and some of their physico chemical characteristics like colour and odour, During a period almost near to that of Vedas. Chandogya Upanishad is one of the earliest Upanishads chronologically coming at par with the Vedas.
An interesting philosophical approach of the metallurgical knowledge is given in Chandogya Upanishad (6.1.6) through one sentence and it conveys a lot about the metals and their processing.
By knowing the nail cutter, all that is related with iron metal can be known...... i.e. Iron is the essence of the tool.
This statement gives us a direct information that when a metal is discussed by its name it is understood that the metal production technology, including the knowledge of ores, metallurgical extraction, purification, temperature connected with all these processing and also the unit operations required to convert the ore into pure metal , was well known
Ancient Indian mines and minerals
Even though proofs have been submitted by Mukherjee 76 on a series of mines utilised for the production of various types of metals during Vedic period, it appears that the earliest description of the mines is given in the Arthasastra written by Koutilya. He has clearly given the duties and privileges of the Director of mines.
The Director of mines is responsible for the handling and proper utilisation of the ores, minerals, chemicals, etc. He should have the knowledge of these materials and their availability. He is responsible for the examination and utilisation of three types of ores classified under bhoomi - prasthara - rasa dhatus. He should know the quality of the ores by means of colour, smell , taste and using the acidic - alkaline textural flavours.
Koutilya focussed mainly the gold, silver lead, tin , coper and zinc ores and metals in his explanations (Arthasasthra 2.6.4) . He has given the correct picture of the utilisation of the resources from the mines as the treasury has its source of income from the mines, from the treasury, the army comes into being, with the treasury and the army, land is obtained. With the treasury is its ornaments, the mines. ( Arthasasthra 2.12.37).
In Arthasasthra the melting process (dravana or vipalana) , solidification process (mruthi)etc., are explained very systematically. Proper heating is required for making the metal alloys says Arthasasthra
As a scientific proof on the metal processing, the carbon dating technique has shown that extraction and purification of the metals like silver, tin, copper, lead, iron and zinc, were undertaken during Koutilyas period (300 BC) and far before that.
Also the best evidences are available for the Sanskrit explanation given by Koutilya on the mines, which can be substantiated by the above techniques. Based on the study reports it could be proved that the Rajpura, Dariba, Udaipur mines in Rajasthan were very active from 1300 BC . The Hatti mines in Karnataka was active from 1000 BC, Ramapura and Agucha mines were exploited for the metals from 700 BC and Zawarmala, Ambamata mines of Rajasthan were actively utilised for the metals from 500 BC. One of the most important observation is that the Kormaranahalli and Tadanhalli mines in Karnataka were yielding iron ores from 1300 BC. The description of iron in Vedas was also due to the fact that mines from Atranjikhera, Pandu - Rajar - Dhibi in Bengal ; Alamghir in Rajasthan and Varanasi in Uttarpradesh were all subjected to a very high level of iron ore production during this period i.e. Also before and during 1200 BC, which is crucial period as far as iron production is concerned.
It is important to search the Sanskrit based information mentioned about the physico chemical characteristics of the ores and minerals of the metals. In Arthasasthra ( 2.12.30) the ores are thus described: The colour of different ores can be yellow, mixed yellowish red, when disintegrated it can have bluish colour, and the colour of green gram, black gram, curd, turmeric, terminelia seeds, liver of animal, spleen, sand, jasmine bud, seed of neem, etc. Some of the ores when heated remain the same and some ejects out smoke and surf.
These descriptions of the ores are perfectly in agreement with the characteristics of the ores of copper, gold, silver, lead and tin .
A series of outstanding descriptions are also given on a variety of minerals and ores of specific metals. The scientific content of these descriptions can be obviously available when those facts are compared with the actual modern knowledge on the subject. The description of the silver ores is given in Artha sasthra:
Native silver ores are of eighteen types. They are classified on the basis of their colour:. the ores having the colour of conch shell, camphor, pearl, jewel, lotus flower, etc., some times the silver ore get mixed with lead and some are white outside and black inside. When heated some of the ores produce smoke. In these ores, the density is directly proportional to the metal content in it.
The copper ores are thus described in the part of Artha sasthra :
The copper ores may have different colours and appearance as: heavy, tawny, green (Chalcopyrite ore) ; dark blue (malachite ore); yellowish tint (azurite ore and pale red (native ore of copper)
This explanation in Arthasasthra agree literally all the qualifications of various types of copper ores given in the parenthesis.
Lead ores are described thus in the book: It is greyish black like kaka mechaka (galena ore of lead), yellow like pigeon bile (gossam ore). (Here too the characteristics agree fully with the descriptions given.)
The tin ores are described in these words by Koutilya:
The tin ores are grey saline or like brown burnt earth (cassiterite ore of tin)
Iron ores are thus described and their modern equivalents are also given:
Iron ores are greasy stone, pale red and having the colour of limonite or of the Sindudrava flower ( haematite ore of iron). The iron ore which has the colour of crow egg or birch leaf is vaikruthaka dhatu ( magnetite ore).
After describing the physico chemical type of characteristics, Koutilya has further mentioned the duties of the Lohadhyaksha. The Lohadhyaksha should establish factories for the production of metals like copper, lead, tin, copper and alloys like vaikruntaka, arakuta, brass , bronze and bell metal . All the business related with the metals should be undertaken by him. Says Artha sasthra:
The subject of metallurgical science inevitably deals with the subject of furnaces, kilns and crucibles used for the production and purification of the metals and alloys. Thus mentioned in Rasaratna samucchaya on the kilns used for the production and purification of the metals:
The equipment used for removing the impurities is known as the Musha/ kiln.
Different types clay is used for the preparation of the kilns. This gives a good information on the ancient Indian background knowledge on the ceramics science.
Yellowish white and heavy sand or reddish white sand that can withstand high temperature for a long time, is the best for the manufacture of the kilns .
Different types of kilns / mushas used for processing a variety of ores and metals are thus described in Rasaratna samucchaya:
Vajra-yoga-vajradravaini-gara-vara-varna-roopya-vida-vruntaka-gostani-malla-pakva-gola-maha-manduka-musala are the names of the common mushas used.
Detailed descriptions are given in the Rasaratna samucchaya on the preparation method and clay composition for the production of the above type of kilns. Different furnaces mentioned are named here based on their sizes, shapes and the purpose they serve.
The temperature for the extraction and purification of a metal is attained according to the nature of the metals and ores. The process by which metals are extracted is sometimes called Kupeepaka vidya. Different types of putas are used for getting specific temperature. All these putas when subjected to the modern tests, are found to provide the temperature between 750 - 900 C. The duration of maintaining the temperature and the dimensions of these putas are given below
Name of the putas dimensions Duration of heat
Mahagajaputa furnace 36" width x depth 150 min
Gajaputa 22 " " 100 min
Varahaputa 16" " " 50 min
Kukkutaputa 9" " " 5 min
Kapota puta On the surface of the earth low temperature
The above time duration was experimentally proved using the modern instruments after making the putas by following the details given in the above mentioned book on the dimensions 77
The above types of putas were made using cubical arrangement of cow dung cakes. For example in mahagajauta, 2000 cow dung cakes were used and in other putas 1000, 800, 40 and 8 cakes , respectively were used.
From this it is clear that there existed a standard set up for the furnaces. Metallurgical process were not adopted as a crude heating procedure. Every puta has a definite specification to follow.
Qualification of pure metals are described in Rasarnava ( 52 -55). The purity of the metal flowing out of the furnace can be judged using these physical parameters.
Pure metal is the one which when melted in crucibles, does not give sparks, bubbles, spurts, lines or scum on the surface. The molten metal which does not produce any sound and is tranquil like gem flows out from the furnace.
The above explanation given agree well with the qualifications on the purity of the samples obtained during archeological studies. The purity of the metal was assayed using modern instruments and found to have the following composition
Name of metal and alloys Place from where obtained % Purity
Copper Nalanda 97.9
Copper Mohenjodaro 97.1
Copper Atanjikhere 97.3
Copper Harappa 98.8
Copper (ii) Harappa 99.0
Silver Mohan jodaro 94.5
Lead Mohan jodaro 99.7
Bronze Takshasila 85.0 % Cu + 9.8 % Sn
Brass Takshasila 55.4% Cu + 34.3% Zn
These metal and alloy samples were produced during a period ranging between 3000 BC - 200 BC
Thus archeological evidences submit absolute proofs for the metallurgical capabilities explained in the Sanskrit literature.
Corrosion of metals: Degradation of metals by way of the reaction with oxygen, moisture, acidic and alkaline materials present in the atmospheric air is a natural phenomena. This is termed as corrosion in modern science. The concept connected with the corrosion and the degradation of metals is clearly mentioned in Rasarnava (7. 89, 90)
Gold, silver, copper, iron, lead and tin are the six types of metals which undergo self degradation at a slower rate in the reverse order of this arrangement. ( the statement means in the reverse order of the arrangement the metals are more and more stable)
I.e. Gold is the least (slowest) corroding and the tin is the fastest corroding metal and the rate of corrosion increases in the order steadily.
Yajnavalkhya smruthi refers to the cleaning of the metals in the Acharadhyaya 78
Tin, lead and copper may be cleaned with alkali and acids. Iron , bronze and copper alloys are cleaned with ash and water.
The rationale being this is that the use of acids and alkalies rapidly decompose and dissolve the corroded impurities accumulated on the surface of the metals and cleanse the surface.
Alloy making: The ancient Indian authoritative knowledge on the production of the alloys has been well appreciated from time immemorial. A number of examples are available from different parts of India for demonstrating the authority on the metallic alloy production. Arthasasthra says that the coins are manufactured using different metals, by alloying. The Director of coins Lakshanadhyaksha has the responsibility of making coins with different denomination as given below:
The Director of coins should know how to make four types of coins: i.e. Coins of one pana, half a pana, one fourth of a pana and one eighth of a pana using copper, silver , lead, iron and if required other metals.
This descriptions gives the scientific way of alloying the metals known during the period of Koutilya. The following statement if further explained with the help of commentaries:
The above statement means; padajeevana type of coins contains 4 parts of silver and 11 parts of copper and 1 part of any other metals like iron, tin, lead, or antimony. This coin is known as Mashakam. Half of this composition known as ardha mashakam, one fourth of this, gives a coin known as kakani, one eight of one pana is ardha kakani.
This gives an upto date type of knowledge of alloy making process for the production of coins, which is one of the sophisticated techniques adopted for getting uniform size, shape, weight and quality for coins
Bronze: Bronze was one of the most commonly used alloy in ancient India. Archeological information available on the bronze is plenty. Bronze and brass are the two alloys obtained from almost all the excavated sites, in India. This shows that, the processes of preparation of bronze was familiar through out this continent. Temples in south India have many bronze and brass statues , idols, big vessels and other items.
Panini s Ashtadhyayee ( 8.2.3.1) gives the information on brass and bronze vessels.
Brass and bronze vessels can be used for storing ghee, milk, etc.
Panini was a contemporary scholar of the ruler Pushyamitra Sunga (187 BC). Rasaratna samucchaya (5.205) gives the composition of one type of bronze as:
Eight part by weight of copper and two parts by weight of tin give the bronze.
Archeological studies support this description , as many bronze samples contained 10 -20 % tin alloyed with copper.
Brass: The Indian technology of brass production is as old as that of bronze. The metal, zinc was called suvarnakara because it converts copper into gold like alloy. Two methods were followed in India for the production of brass. First method, by directly alloying the copper and zinc and the second is by alloying copper with zinc minerals, like calamine. Rasaratnakara (3) gives this explanation:
What wonder is that calamine ( zinc ore) roasted thrice with copper convert the latter into gold ( gold coloured alloy - brass)
The procedure explained here is the direct alloying of copper with zinc ore. Zinc metal from the calamine ore alloys with copper to give brass. Modern metallurgical studies have shown that the maximum content of zinc which can alloy to form the brass, from zinc ore is 29%.
Majority of the brass samples obtained during archeological excavation contained less that 28% zinc. This proves the common procedure adopted in ancient India was as given in the above Sanskrit lines, alloying by hating copper with calamine (zinc) ore.
Rasarnva (7.34 -38) gives thus on the brass alloy formation:
Zinc, a metal like tin converts copper into gold.
This line is partly repetition of that from Rasaratnakara . Hence the word gold is to be interpreted as gold like
Panini in Ashtadhyayi (5.1.30) has mentioned the word Suvarnakara for tin/zinc while discussing the coins made of copper by alloying with tin / zinc.
Brass samples obtained from Lothal contained 6.04% zinc and 70 % copper. This belongs to the period of 2200 BC. Earliest brass sample obtained, containing more than 28% zinc, was from Takshasila (4th century BC). Obviously, here the zinc metal was alloyed directly with copper, since the zinc content in the alloy was above 29%. Rasaratna samucchaya ( 5.191 -193) gives the description of brass as follows
Brass is of two kinds which are known as reetika and kakatundi. The former when heated and plunged into sour rice gruel turns into copper colour and the latter turns black by the above treatment. The former is heavy, soft, yellow, resistant to hammering, brilliant and smooth.
This explanation stands scientific as far as the qualifications of alpha and beta types of brass are concerned. The brass which contains less than 28% zinc has all the above said property and it is known as alpha brass, where as the second one is beta brass that contains above 28% zinc in it.
Bell metal: The qualification required for the bell metal alloy is different from those of other types of alloys. It should give a perfect, melodious and attractive sound. The bell metal alloy is mentioned in Arthasasthra. Method for separating copper from bell metal is described in Rasaratna samucchaya (8.37)
Molten bell metal is heated with a little tala or orpiment, blown with a bent tube and freed from Ranga of tin and what we get is the copper separated from bell metal . (Ghoshakrushtam thaamram means the copper extracted from bell metal). This copper may contain traces of other metal components also, hence may have special grade and quality.
Panchaloha: Panchaloha is the most common alloy used in making idols in temples for the last few thousand years. Sanskrit and regional language literature give detailed description on the panchaloha vigrahas. Charka samhitha gives this explanation (1.70)
In pancha loha , gold and separately copper, silver, tin, lead and iron are alloyed.
In Rasaratna samucchaya (5.212) panchaloha alloy is separately described as follows:
An alloy of five metals of tin, copper , brass , iron and lead is called panchaloha.
Metal seal:
Bruhath samhitha of Varahamihira (57 -1.7) gives the explanation of a metal seal known as Vajrasanghatha.
An alloy of eight parts lead, two parts bell metal and one part brass has been described by Maya as the vajra sanghatha metal seal.
Pure metals:
Copper: Yajurveda mentions about copper, in the name thamra. Copper metallurgy has got a long tradition in India. Mehargarh excavation has shown that the copper samples obtained from there belonged to 8000 BC. One of the many samples obtained from this site recorded the production period which can be around 7786 +/- 120 BC. More than 2500 copper samples could be excavated from different archeological sites.
As far as the Sanskrit literature is concerned, it appears that Arthasasthra comes first in the description of copper, other than Vedas. The earlier mentioned are the descriptions of copper ore and various alloys made of copper. The purity of copper metal obtained from Harappa was 99% and that obtained from Mohen jodaro was 97 %. Ancient copper technology should have been good to get this level of purity for the copper metal.
Iron: There are evidences available from Mesopotamia, Egypt and Afghanistan on the efforts taken in the production of iron during 3000 - 2000 BC. Similar trials were also conducted in Cyprus during 1600 BC 80 . Historical data proves that upto 1600 BC, none including Greeks and the Mediterranean people could produce iron. After putting all the evidences together, it can be concluded that till 1200 BC, iron production was not conducted succesfully anywhere in the world, other than in India. Yajurveda mentions about iron as syamam and also loham. In Susrutha samhitha and Charka samhitha, the use of iron based drugs for treating the anemia as an asavam is mentioned. This asavam is known as Loha asavam:
For years together, the iron nails are treated/stored in ghee and that ghee is used for the preparation of iron asavam.
Archeological evidences show that iron was commonly produced in five regions in North India during or prior to 1200 BC. An iron sample obtained from Ahar was dated during 1300 BC. Rasaratna samucchaya gives defintion and explanation for the three types of iron ( Rasaratna samucchaya 69)
Three important classes of iron are Munda loha ( cast iron), Teekshana loha (carbon steel) and Kanta loha (soft iron).Further classification can be seen in the explanation of each of the above type of iron The Munda loha is of three kinds; mrudu, kunda and kadra.
Theekshna loha is of six types. Khara, sara, hrunnala, trivrutta, vajra and kala
Kanta loha is of five classes which are bhramaka, chumpaka, karshaka, dravaka and romaka.
It is an interesting information to note that the above classes and subclasses are well defined in modern science, with physico chemical characteristics of the product.
In Rasaratna samucchaya, the qualities of roasted iron (which is iron oxide) and the rust of iron ( it is also the iron oxide) are compared (148)
The qualities of the air roasted iron and the rust of iron are the same. Therefore the latter was also acceptable for medicinal purposes.
Carburisation is a process of hardening the iron which is achieved by inducing more carbon in the metal by heating. This method is of special use in hardening and sharpening the iron tools like swords. Bruhath samhitha (50.26) explains the method of carburisation of iron.
The iron weapons treated with a day old solution made of the burnt powder of bananas, mixed with butter milk and then sharpened properly, will not break in stones, nor become blunt on other instruments.
Carburised iron weapons were spotted in many places by the archeological study groups. The process of carburisation has been discussed in detail by Bhatia 80 b . The quality of Indian steel has been referred to by Ktesias who was in the court of Persia in the 5th century BC. Swords made in India were purchased by Persian kings. Alexander the Great was said to have received 30 pounds of Indian steel in 326 BC, from King Porus for making Damascus swords.
The above information are important historical evidences on the capability of iron metallurgy in India and also the quality of the metal produced here. They also support the scientific explanation given in the Sanskrit literature.
Silver: Silver metallurgy was known to Indians at least from the period of Mohanjo daro civilisation. A variety of silver articles was obtained from there. Arthasasthra describes silver as follows (2.13.31)
Silver has the colour of jasmine bud. It contains a lot of lead, it may have the colour of sky, it is white, soft and also precious. When mixed with 4 parts of lead, the alloy will have the colour of fresh curd.
Artha sastra describes the purification method of silver as a continuation of the above lines:
The impure silver is mixed with bone powder, 4 parts lead, 4 parts sand, 4 times cow dung, 3 parts kopal together 17 parts. This mixture is taken in a kiln, mixed with salt and sand and melted. The pure silver gets separated in the pure form. If mixed with some gold, it adds to the lustre of silver.
The above two explanations fully agree with the scientific observations on silver metallurgy and charecteristics. In fact this is the actual process adopted for the removal of impurities such as lead, iron,etc from the silver during its extraction process.
Qualifications of silver are further explained in Artha sasthra ( 2:14:33)
If silver is mixed with lead, it gives an alloy with a bad smell. The alloy will be rough, less coloured and less shining in appearance.
This silver has to be purified with the bone powder in a furnace ( if lead is to be removed)
This concept explained is practised in the modern cupellation process also, for the purification of silver. Instead of the calcium and phosphorous present in the bones, calcium phosphate lining is directly given in the crucibles, known as cupels , in the modern process. Detailed description of other silver alloys is given in Artha sasthra ( 1.13.31)
An alloy of 3 parts of copper and 28 parts of silver has the colour swetha lohita. The alloy with 3 parts of gold and 28 parts of silver has a colour peetha raga.; two parts of silver and one part of gold give an alloy with green gram colour . Two parts of silver, one part of gold and 1/6 iron give black coloured alloy which when mixed with mercury gives silver with a colour of golden bird s feather.
These descriptions give us full information on the technology adopted for making different types of silver alloys and also their physical characteristics. The description continues and some more varieties of silver alloys are mentioned:
The alloy of two parts of silver and one part of copper is known triputakam; one part of iron and one part of silver is known as vellakam; one part each of iron, silver and gold is known as vellakapasaritham. One part each of copper and gold is known as hemapasaritham.
Almost all these types of alloys could be located from various archeological centres during excavation studies. One sample of the silver alloy obtained from Mohan jodaro had a silver content 94.5%. Rasarnava (12.42.2) gives the colour of silver- gold alloy
Twenty five percent gold with silver will have the colour of pure gold.
Rasarnava (12.49.2) says that for sales purposes the above alloy can be further mixed with silver..
Thus the literature descriptions and the practical observations on silver are scientifically agree to the highest level of accuracy.
Mercury: Mercury is a liquid metal which is described in all the Rasachikitsa books written in Sanskrit. Charaka samhitha and Susrutha samhitha give detailed description on mercury and many of its physico chemical characteristics including some of the compounds like oxide, sulphide, sulphate, etc.
Rasaratnakara (37) gives this explanation on the distillation process of mercury extraction
The mercury ore (known as darada ) when distilled in a distillation set up gives drops ( of mercury ) with the help of water (when condensed the vapour with water)
This is also the modern procedure adopted for the separation of mercury from its ores like calamine. In Rasaratna samucchaya (8.64) the following description is given
When the refined ore of mercury is heated in a distillation set up, the vapours move up, down and sides. When condensed with water, it gives drops of mercury which can be collected . This mercury when reacted with tin, a solid amalgam is formed.
Rasaratna samucchaya ( 3.141,144) describes the mercury distillation process
When the mercury ore is distilled and the vapours are condensed, it gives the mercury known as suta. ( this explanation is also application for zinc)
Lead: Rasaratna samucchaya (5.171) gives this definition for the metal lead:
Readily fusible, very heavy, having a black and white appearance on fracture having off foetida odour and black on the outside surface is the lead.
This gives an absolute characteristics of the metal lead. The purity of lead obtained from ancient sites of Mohan jodaro was 99.7%. This is a proof on the quality of the lead production technology existed here . As mentioned earlier, the lead was used for making the metal seal known as vajra sanghath an alloy containing lead as an important component. (Bruhath samhitha 57.1.7). Rasaratna samucchaya gives one of the applications of lead ore as a hair dye (3.146)
Hingularda or cinnabar was known to occur in two varieties; inferior and superior grades, The ore coming from Gurjar province near the Abida mountains, coloured yellow with lamella, can be used for preparing hair tonics or dyes.
Zinc: Zinc is an ash coloured low melting metal. It has been described in this thesis under the alloy brass. The detailed description of the production of zinc metal is given in Rasaratna samucchaya.
Brinjal shaped crucible is attached with a 12 angula long tube over it like an inverted flower of dhatura. A hole of 8 angula diameter is made in the tube. This crucible is used for the
zinc distillation (Rasaratna samucchaya 10.22,23)
A series of brinjal shaped crucibles, set up in series as rows, were found during the excavation of zinc producing sites in Rajasthan. Dozens of crucibles thus arranged in 6 x 6 sets, used during 1500 BC or before, could be located from these sites.
In Rasaratnakara (31,32) the flow of zinc metal from the distillation set up is thus described:
There is no doubt that this process yields an essence of metal (zinc) of the appearance of tin, from the crucible known as mooka musha.
Crude tin resembles the zinc metal. Biswas 82 has given a detailed description on the metallurgical process of ancient Indian technology on zinc production. He has concluded here that the brass containing 36% zinc, was produced in India directly by alloying zinc and copper. The brass samples containing 46% zinc is brittle and those containing 36 - 46% zinc were of medium texture. This type of products were also obtained during the excavation. Some of the brass samples of the Vedic period belonged to alpha and beta types.
A zinc sheet was excavated from Agora, a town in Athens, Greece. It has been proved that this sheet was produced in Takshasila in the 3rd century BC.
A number of historical and archeological evidences support that the zinc production in India started many millennia ago. This technology was smuggled to the West , first in 1597 AD, by a metal smith Libavius 83 . In 1616 AD, the name Zinc was given to this metal by Parcelius. ( till then this metal was known in West as Malabar lead). Later on, William Champion, a metal smith from Warmeley, UK. who collected the details of the metallurgical process from Rajasthan, applied for the patent in UK. It is said that a person by name Dr.Lane visited Rajasthan for collecting the details of the zinc extraction process84 and the technology was spread from there. Thus Indian technology on the production of zinc metal got directly and indirectly transferred to the West, during the 16th and 17th century AD
Tin: The metal tin has been discussed in detail in almost all the Sanskrit Rasathanthra books. Rasaratna samucchaya ( 5. 153, 154) describes, in detail the qualifications of alpha and beta type of tin.
There are two types of tin known as khuraka and misraka. Khurakam is the superior quality tin and the misraka is the subordinate one. Khurakam type of tin is white , soft, flexible, tooth coloured, dense, without making the metallic sound which is beta tin and the mixed black and white coloured one is the misraka, the alpha tin.
Rasopanishad gives a detailed description on production, purification and alloy making with tin metal. The full chapter description on tin can be seen in Vangasthambhana sodhana adhyaya of the Rasopanishad. Rasarnava (7.112) gives the process for the purification of tin metal
By putting powdered bones of buffalo in the crude molten tin metal and sprinkling its urine, the tin can be produced and purified from its ores.
The bone powder acts as the source of calcium for the tin purification by acting as the flux in the removal of the impurities. The phosphorus present in the bone reacts with atmospheric oxygen to form phosphorous oxide and in presence of water, the phosphoric acid is formed, which purifies the tin.
The modern technology for the production of tin came to be known in Europe only in the 16th century AD through a metallurgist Agricola 85 where as in India the metallurgy of tin has a history of thousands of years. The metal is also mentioned in Yajurveda as thrapu.
Vijay Deshpande 86 has conducted detailed studies on the ancient Indian technologies on tin. Particularly the details given in the Rasopanishad and proved that all the descriptions are scientifically true. He prepared a variety of tin alloys by following the descriptions given in Rasopanishads. One alloy of tin giving a marvellous appearance is described in Rasaratna samucchaya (20 -2)
Tin with mica and equal quantity of gold are placed in a closed crucible along with a plant product known as vimala and roasted. It is accomplished in a koorpathootha to get an alloy of metal resembling emerald in colour and lustre.
Dr. Pandy has proved the quality of the alloy by producing the same. Many similar explanations are available in the Sanskrit literature on tin based alloys . A variety of tin alloys were also excavated from the archeological sites. A few examples are given with bronze alloys.
Gold: Gold is a metal well known to Indians for many millennia. It is mentioned as a synonym for the wealth and property in Vedas. Gold purification has been explained in Arthassthra (2.13.31)
Different types of gold having various colours mixed with lead and converted into metal sheets, mixed with cow dung cakes, sand of Sourashtra and salt. This is then heated strongly to get the best coloured gold, in bluish white, greenish, dove coloured, etc
Many alloys of gold for coin making are described earlier in this chapter. One such alloy referred to is given in Bharadhvaja s Amsubhodini 87 .that alloy is prepared as follows:
Eight part of potassium iodide, 16 parts of copper of chuleethamra grade (one out of 16 grades available) , 8 parts of gold namely hiranyaka grade, ( one out of 12 grades of gold known). 6 parts of arsenic sulphide, 5 parts of mercury, 6 parts of quarts are heated in a crucible of tortoise shape and melted at 432 temperature and then poured the molten alloy into the mould.
This alloy was prepared by prof. Dongre 87 and proved the descriptions are well in agreement with the facts mentioned.
Thus Sanskrit literature carry a lot of information on the subject of metals and alloys. Many of these alloys and some of these methods might not even have come to the notice of the modern scientists. Hence it is worth while to peruse into the subject by which one can fetch better or more useful information on metals and their alloys
CONCLUSION
There were hundreds of books written in Sanskrit discussing the subjects of mathematics, astronomy and metallurgy, which are the original contributions of ancient Indian scientists
Hundreds of commentaries were written in Sanskrit and in other languages which also contained original contributions other than detailed explanations of the methods, process and data of the original book.
Many books, data and technology were transported/smuggled/taken/donated to foreign countries during or before or after the renaissance period, in the West.
Many of these books were translated in foreign languages by scholars. Original books and their translated versions have also spread to different countries.
During the renaissance period many European scholars studied these books and brought into light the original scientific content in them. Some of these knowledge have been utilised by the Europeans and others. Some of them were claimed by the foreigners .
In these books information on almost all the aspects of the modern mathematics are given. These contributions start from the number system to the most complex geometrical parameters and theorems.
Many of these discoveries are original contribution of Indians which are at present known in the names of the Europeans or Western scholars. Many more theorems are still unknown to the world of mathematics even now.
The Indian concept of astronomy and geography is perfect modern knowledge, which are at par with the latest observations.
Many details available in the modern astronomical books are also available in the ancient Indian astronomical books, some which may need more refinement.
Some of the latest views on modern astronomy perfectly agree with the knowledge that is thousands of years old, which originated in India.
Much of this knowledge has been obtained as a result of the original experiments and studies conducted by ancient Indian scientists.
A variety of instruments have been explained for the determination of the astronomical data. They were all arrived at based on the scientific observations. In many cases only the conclusions are given in the Sanskrit books.
Detailed observations and scientific data are presented against the superstitions mentioned as the stories in the Puranic texts.
As far as the metallurgical part of the thesis is concerned , data available shows that mines, minerals, metals, ores, etc, are described in detail , in Sanskrit literature. These descriptions are substantiated by the archeological observations.
The solid proof of the metallurgical capability available are from the archeological sources of these metals and alloys from various sites spread over this nation.
Ancient indian metallurgical science ebook