¢ 
264 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
and a heavy ax with a tang (No. 12) from Ecuador, of hard and 
sonorous copper quite remarkable in its quality. The two bolts from 
Tiahuanaco (Nos. 1 and 2) were the only Bolivian copper pieces 
analyzed. 
Like all products of a primitive metallurgy, the bronze objects con- 
tain, besides copper and tin, certain other metals, but in a very small 
proportion. 
The majority of the analyses showed lead (from 0.07 to 1.80). In 
only two specimens was found more than 1 per cent. 
Zine was also discovered in several disks from Argentina (from 
0.81, to 1.65). . 
Antimony was encountered in very small quantities, but quite uni- 
formly in all the Bolivian bronzes (generally 0.06, rarely up to 0.17), 
while it was totally lacking in those from Argentina. 
Bismuth ‘was found in several of the Argentine bronzes (from 
0.23 to 0.82). 
Two Argentine disks contained nickel (0.78 and 2.04). 
Silver was just as scarce. A disk from the Calchaqui region 
showed 0.22; two others merely tracts. 
On the other hand, the analyses of nearly all the bronzes gave iron 
in proportions varying from 0.08 to 1.79; but, of thirty-four pieces, 
thirty-one contained less than 1 per cent. It is perfectly evident 
that the iron, as well as the other accessory metals just considered, 
was not introduced into the composition of these bronzes intention- 
ally. They were probably found naturally either in the copper and 
tin ores used in the manufacture, or in the attle around these ores. 
As to the essential constituents of these bronzes, copper and tin, 
their proportions are very variable. The specimens from Tiahuanaco 
contained from 5.83 to 7.70 per cent of tin, while those from Yura 
from 2.10 to 10.72 per cent. In the bronzes from the Argentine 
Republic the variance was even greater—from 1.57 to 16.53. Alto- 
gether, of forty-one pieces, only four were found containing more 
than 10 per cent of tin, the normal proportion in bronze. The mix- 
ture of these two metals was certainly intentional. It furnishes us 
with irrefutable evidence that the tribes living in the mineral-bearing 
regions of the Bolivian and Argentine Andes before the advent of 
Europeans were familiar with tin, which they knew how to extract 
and alloy with copper. But the unequal proportions of tin shown 
in their bronzes demonstrates that they possessed only quite rudi- 
mentary ideas on the metallurgy of this latter metal. 
We have seen by the impurities brought to light in the analyses 
that the refining of metals was very imperfect. Likewise the com- 
bination of their constituents seems to have been rather empirical. 
It has been shown, for example, that it is not in the objects in which a 
