The i)resfnc>' of iii:iii\ ovnaiiiriit.s .-iiid impli'iiuMits of Iironzi- in prehistoric Peruvian b.irials litis 

 raised much discussion as to whether tlie ancients knew the secret of combining copper and tin in 

 proper proportions to make the harder metal or whether its production was accidental. Among the 



articles found ai'e ktiivrs. nccdl-s. Iiattli' axes, chisels, and shawl i)iiis 



Prehistoric Bronze in South America 



15v (HA I{ L H S \V. M H A 1) 



Tl I Fj (lisfovery by i^rimitive man that 

 certain kinds of stone or mineral 

 would yield a niotal on application of 

 heat, made possible an advance in civilization 

 relatively as important as any that has fol- 

 lowed. Metal implements superseded the 

 more clumsy and inadequate tools of stone, 

 and metallurgy became an established sci- 

 ence. 



Bronze, an alloy of copper and tin, is 

 obtained by smelting these metals together 

 in proportions which may be varied accord- 

 ing to the nature of the product required. 

 The addition of tin to copper makes a 

 combination which not only is more fusible 

 than copper alone, but also harder and less 

 malleable. It is therefore more suitable for 

 casting and more useful for making imple- 

 ments. Copper and tin are reduced quite 

 easily, unlike iron, which requires a greater 

 application of heat to separate it from its 

 ore than it was possible to obtain by primi- 

 tive methods. In the hands of the ancients 

 these metals ai-e responsible for what is 

 generally known as the Bronze Age of cul- 

 ture. 

 574 



It has seemed probable that the original 

 discovery of bronze and its advantages over 

 copper were a matter of chance. It is pos- 

 sible that the metals often found in copper 

 of the early bronze age were not intention- 

 ally added but were the result of smelting 

 impure copper ore. Later, when experience 

 had shown that the combination of copper 

 with other metals yielded a product superior 

 in many ways to copper alone, the additions 

 were made purposely. 



Strictly speaking, the term "copper" 

 should be applied to all implements which 

 contain ninety-six jier cent or more of this 

 metal, the remaining four per cent being a 

 mixture of two or more other metals in 

 varying proportions, with occasionally some 

 sulphur and less than two per cent of tin. 

 Such alloys come under the accidental 

 category, although in exceptional cases, such 

 as the tin and copj^er ores of Cornwall, a 

 much larger proportion of tin may be acci- 

 dental. 



It has been af3firmed by some that bronze 

 could not be produced by smelting a copjier 

 ore containing tin. Experiments with the 



