ELEMENTS, COMPOUNDS, AND MIXTURES 253 



the stamp mills, pulverized ores of gold and silver are 

 mixed with water and allowed to pass over layers of 

 mercury. The mercury dissolves the particles of gold 

 and silver. Later they are separated by distillation. 



Copyright by Underwood & Underwood, N. Y. 



FIG. 223. Copper Ore Just Hoisted from the Shaft, Calumet and 

 Hecla Mine, Michigan. 



Sodium. Sodium is a very soft metal and may be 

 easily cut with a knife. The surface of freshly cut sodium 

 has a luster resembling that of silver, but it soon tarnishes 

 when exposed to air or moisture. To keep sodium we 

 cover it with kerosene, or some oil which contains no 



