History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c13.s2.t3.9

v1.c13.s2.t3.9

It is so soft that it can be scratched even with nail hence it’s use has been mostly for the manufacture of cheap jewellery dies or pattern for shaping other metals, and as a hardner in copper alloys. In South India lead coins have been in use in Ist-2nd century B.C and it was the chief coinage metal for considerable time. It melts at 327°C and its B.P. is 1525°C. Besides PbS (Galena) it also occurs in nature as PbO i.e., Massicot and Litharge (Yellow in colour), PbCO₃ or Cerussite and white lead PbCO₃.Pb(OH)₂ (white powder) or PbSO₄.PbO (white pigment). Lead might have first been recognised as these coloured pigments used for body decoration and during use it might have fallen in the compfire producing metallic lead, because these minerals get decomposed easily to PbO and subsequently reduced to liquid lead at 500°C. The reactions occuring during the roasting of Galena are -