Pramāṇa · Search · About · API

History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c13.s2.t10: (ii) Silver Alloy

History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c13.s2.t10

Language
English

(ii) Silver Alloy

v1.c13.s2.t10.1

As described earlier while Gold was liked for its highly appealing Golden Sun like colour, Silver was recognised for its cool white appearance similar to that of Moon. Silver utensils were very common in wealthy household because they are resistant to the attack of organic acids and alkalies and all kind of food could be prepared and kept in it for many hours. Silver jewellery had its own attraction for dark coloured Indian women.

v1.c13.s2.t10.2

In latter period with the development of coins instead of barter system of trade (700 B.C.) Silver coins were made from Ag- Cu binary and Au-Ag-Cu ternary alloys. Bharadwaj (1987) has published recently a very comprehensive paper on a large number of these alloys used in Numismatics. Silver coin ‘Rūpa’ has been specified to be made of ‘Sarametal’ containing 11 part Ag, 4 part Cu and 1 part of Fe and Pb etc. This clearly indicates that the alloys were purposely made by mixing the pure metals in a definite proportion. At that time no method of chemical analysis or metallography was available, even then the composition controls in a very narrow limit was maintained as revealed by the chemical analysis off our hoards of silver coins done by Prasad and the study of silver coins from Rajghat and Gupta period done by Saran (1989).

v1.c13.s2.t10.3

The Silver coins from Gupta period has been found to contain 27 to 28% Cu i.e. corresponding to the near Eutectic composition of the alloy. As shown by Ag-Cu phase diagram in Fig. 45 the Eutectic alloy (Ag-Cu) containing 28.4% Cu has a melting point of 779°C only i.e. much lower than any of these pure metals. Kautilya’s Arthaśāstra describes in great detail the process of manufacture of these alloys and the techniques applied for minting coins which used to have a definite weight. In the beginning these coins were square in shape and their weight was controlled by cutting the required piece of metal from one corner. When the minting of circular coin was begun its weight was controlled by taking a weighed quantity of the alloy and punching out dimensionally controlled coins having the desired punch marks. The study of the punch marks on ancient coins have revealed high level of craftsmanship in the preparation of punching dies. The study of coins of the medieval and latter period have indicated the use of rolled sheet of controlled thickness.

v1.c13.s2.t10.4

Fig. 45. Ag-Cu alloy phase diagram

Cites (1)