2IO 



THE POPULAR SCIENCE MONTHLY 



Sketch map of northern Chile, showing approximate location of nitrate lands (black 



areas). Cross-lined area on small map of South America 



shows location of nitrates province. 



tening white compound, salty and bitter to the taste, like some sea 

 plants, and capable of absorbing a great amount of moisture. Chem- 

 ically the substance is sodium nitrate (ISTaNog). Pure nitrate is founl 

 only in small quantities or "pockets." Commonly it is mixed with 

 earthy materials and various saline compounds, as common salt, 

 Glauber's salt and borax. A small amount of iodine compounds also 

 are present in most cases. This impure raw material is known as 

 caliche to the nitrate miner. 



Caliche, unlike many raw forms of minerals, is easy to get at, for it 

 lies on or near the surface. In some places, the caliche is covered with 

 25 or 30 feet of fine dust (chuca) and coarser rock waste (costra) 

 which must be thrown aside by the miner. In such places, an area which 



