12 USE OF GOLD AND OTHER METALS 



euce tliat pieces now in my possession exhibiting this i>heuomenon may 

 have been tampered with b3' the whites. In tliis connection attention 

 shoukl be caHed to the fact that history is not silent on the matter of 

 plating-. The Indians of New Grenada are not only said to have been 

 marvelously skillfnl in the manipnlation of metals, but, according to 

 BoUaert, Acosta declares that these peoples had much (jilt copper ,^ 

 "and the copper was gilt by the use of the juice of a plant rubbed 

 over it, then put into the fire, when it took the gold color." ^ Just 

 what this means we cannot readily determine, but we safely conclude 

 that, whatever the process hinted at in these words, a thin surface 

 deposit of pure gold, or the close semblance of it, was actually ob- 

 tained. It is not impossible that an acid may have been applied which 

 tended to destroy the copper of the alloy, leaving a deposit of gold upon 

 the surface, which could afterwards be burnished down. 



It has been suggested to me that possibly the film of gold may in cases 

 be the result of simple decay on the part of the copper of the alloy, the 

 gold remaining as a shell upon the surface of the still undecayed portion 

 of the composite metal; but the surface in such a case would not be 

 burnished, whereas the show surfaces of the specimens recovered are 

 in all cases neatly polished. 



Jf we should conclude that the ancient Americans were probably able 

 to secure in some such manner a thin film of gold it still remains to in- 

 quire whether there may not have been some purely mechanical means 

 of plating. In some of the Ghiriquian specimens a foundation of very 

 base metal appears to have been plated with heavy sheet gold, which 

 as the cojiper de{;ays comes off m tiakes. Occasional pieces have a 

 blistered look as a consequence. Were these people able with their 

 rude appliances to beat gold out into very thin leaves, and had they 

 discovered processes by which these could be applied to the surface of 

 objects of metal f 



The flakes in some cases indic?ite a very great degree of thinness. 

 Specimens of sheet-gold ornaments found in the tombs are thicker, but 

 are sufficiently thin to indicate, if actually made by these jteople, that 

 almost any degree of thinness could be attained. It would probably 

 not be difficult to apply thin sheet gold to the comparatively smooth 

 surfaces of these ornaments and to fix it by burnishing. 



Mr. Kunz suggests still another mention by means of which plating 

 could have been accomplished. If a figure in wax were coated with 

 sheet gold and then incased in a clay matrix, the wax could be melted 

 out, leaving the shell of gold within; the cavity could then be filled 

 with alloy, the clay could be removed, and the gold, which would adhere 

 to the metal, could then be properly burnished down. 



It will be seen from this hasty review that, although we may conclude 

 that casting and plating were certainly i)racti('ed by these, peoples, we 

 must remain in ignorance of the precnse methods employed. 



' Bollaert, Ethnological and other Kescarchcs in New Granada, &c. 



