Guest guest Posted August 19, 2004 Report Share Posted August 19, 2004 > INDIAN TECHNOLOGICAL HERITAGE >In the service of our Motherland > A.V.Ajil Kumar > IISH,Chennai. > > TECHNOLOGY OF TIN > > Tin metal and alloy making have a long history in India. Bronze > articles obtained from Indus valley were found to contain 4.5 to > 13.2 % tin. In the West, till 16th century, tin remained > unknown. Agricola, a metal-smith introduced this metal to the > Europeans. > > In Yajurveda , we have seen the word, thrapu used for tin. > Kautilayas Artha sasthra and Charaka samhitha explain this metal > very clearly. Variety of alloys made out of tin have been mentioned > in the Sanskrit books and their existence could be proved from > archeological evidences. > > The composition of bronze obtained from Takshasila showed that > all the samples contained more than 20 % tin. > > Explanation on the physical characteristics of tin ore is given in > Artha sastra(2:12:30) : "Ooshara karbura pakva loshta varna vaa > thrapu dhaatu" > > The tin ore is a grey saline or brown like burnt earth, in > colour . This explanation is suitable for the ore cassiterite. > > Extraction of tin is explained in Rasarnava ( 7 : 112) the book > written in the 11th century AD.: > "Maahishyasthi choornena vaapatthanmoothra sechanaath vangasuddham > bhavedagnow" > > By the use of the powdered bones of buffalo in the crude molten tin > and also spraying the urine/water on it the tin is purified. > > The chemistry of tin purification can be thus explained: The tin > ores containing the phosphorous gets converted into phosphorous > oxide During heating, the oxide gets dissolved in the water > present in the urine, resulting in the formation of the phosphoric > acid. The acid reacts with tin oxide and converts it to tin i.e > reducing the tin oxide to tin metal. > > The cassiterite ore of tin, after roasting is subjected to > smelting with carbon, in a reverberatory furnace. During this > process the tin oxide in the ore gets reduced to crude tin, which is > further refined. This is the modern process. In the above ancient > process plant materials are added as a source of carbon and calcium > based bones were used as the source of flux. > > Molten tin is described in Rasaratnakara book: > > "Mookamooshagatham dhmatham tankanena samanvitham > satwam kutilasankasam pathathey naathra samsaya:" > > There is no doubt that the metal flowing out of the mooka musha > crucible ( which is specially designed for this type of metal > extraction) as the essence of the ore is the metal tin. > > In the modern tin processing, the Bessemer convertor which also > has the same shape of the mooka musha, but has larger size is > used . In this convertor, the ore is mixed with carbon and > processed,. > > Method adopted for the production of tin is also given, in the > Rasopanishad, in the chapter devoted for tin and tin alloys. The > explanation is as given below: > > "kutajaarka vita kshaare nirgundee brahma vrukshayo: > gandhagokshurake brahmyanthaayaam nishechayeth > sanchoornya sarvaanyastheeni visha beeja samaani cha > prathi vaapya bahoon vaaraan thilathaile nishechayeth > evam siddham bhaveth vankam sanka ksheerendu sannibham" > > The solution of the ash of the plant kutaja, arka and vida are > sprinkled to the molten tin and also the ash solution of nirgundee, > brahmee, gandha and gokshurava. The powdered bones, visha and > bija are also mixed in equal proportions. . After mixing several > times the oil of sesamum is added. (After heating to the required > level) The tin thus obtained resemble the conch shell, milk and > moon in colour and lustre. > > Explanation of two types of tin is given in Rasaratna samucchaya > (5:153) > > > "Khurakam misrakam chethi dvividham vangamuchyathe. Khurakam thathra > gunai sreshtam misrakam na hitham matham. dhavalam mrudulam > snigdham danthadraavam sagouravam nissabdam khuravangam syaan > misrakam syaamasubhrakam" > > There are two types of tins known as khurakam and misrakam. B tin > is the high quality tin which is known as khurakam and not much > accepted one is misrakam. Khurakam is white, soft, flexible, tooth > type , dense, without making metallic sound and the misrakam is > blackish white in appearance. > > It is in the 20th century the modern science could identify the two > types of tins, where as ancient Indians had the technology to know > the difference of these two. The Sanskrit word, misrakam, makes > it clear that it is a mixture type having metallic and nonmetallic > properties. This misrakam is lower grade tin, but it gets > converted into beta tin at about 13 C. > > Rasopanishad is a Sanskrit book probably of the period 13th > century AD. The 13th chapter of this book is fully devoted for > tin , hence the chapter is known as vangasamsodhanadhyaya. Detailed > experimental work has been carried by Dr. Vijay Deshpande to > examine claims made in this chapter of the book. He has > published the study results. > > Vijay Deshpande ( Indian journal of the History or Science 121: > 1992) has proved that the plant products mentioned in the > Rasopanishad to reduce the tinstone ore is perfectly in agreement > with the technology of the tin production. The carbon gets > replaced by the plant materials. > Quote Link to comment Share on other sites More sharing options...
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