[652] ANALYSIS OF SOME BOLIVIAN BRONZES J 



THROUGH the kindness of the authorities of the American 

 Museum of Natural History, we were enabled to analyze por- 

 tions of certain implements collected in the region around 

 Lake Titicaca. It will be seen that these metals differ remark- 

 ably in composition, and indicate the possession of consider- 

 able metallurgical skill by the inhabitants of that region. 

 The absence of the slightest traces of silver may be taken as a 

 proof that the tin was derived from cassiterite, rather than 

 native tin. The composition of Specimen IV suggests its 

 preparation from domeykite, or some other copper arsenide, 

 fairly free from sulphur. Owing to the small mass of samples, 

 which were drilled or cut from the specimens, the density 

 determinations, made with water in a pycnometer, are only 

 approximate. In Specimen VI the porosity of the material 

 undoubtedly occasioned a low result. Tin and copper were 

 separated by potassium [653] polysulphide, the former deter- 

 mined as stannic oxide and the latter electrolytically. Ar- 

 senic was separated from copper by Crookes's method, and 

 sulphur was weighed as barium sulphate after oxidation with 

 nitric acid in a sealed tube. 



I. Museum No. 1842. Small chisel or pinch-bar, 18 X l| xj 

 inches. Very tough. Density, 8.68. 



II. Museum No. B-1840. Implement 5-6 inches long, 

 very hard and tough; pale color. Density, 8.94. 



III. Museum No. 1959. Thick wide chisel 4| inches long, 

 tough but less hard. Density, % 8.92. 



1 In collaboration with S. R. Morey. Reprinted from Journal of the American 

 Chemical Society, 32, 652 (1910). 



