394 REPORT OF NATIONAL MTTSEUM, 1899. 



The nitrate deposit is quarried by blasting- with a coarse-grained 

 powder, of which as much as 150 pounds are sometimes used at a 

 single blast. Neither dynamite nor nitroglycerine is used, as it 

 would shatter and pulverize the caliche so as to occasion a serious loss. 



After l)eing brought to the surface the caliche is carefully assorted 

 by experts, broken into pieces double the size of an orange, and carted 

 to the retinery establishment, situated on the pampas or on the sea- 

 coast, or carried to Iquique, Pisagua, Patillos, and Antofagasta by 

 rail, all of these places having connection, l)y narrow-gauge rail- 

 ways, with the nitrate deposits and which, consequently, are rapidly 

 becoming the chief centers of nitrate production and export. 



According to the reports of Consul-General Walker, the southern 

 limit of the nitrate fields is in Antofagasta province, latitude 25° 45' S., 

 and the northern in latitude 19° 12' S., its extreme north and south 

 length l)eing some 260 geographical miles and its average width some 

 2i miles. 



This narrow strip of nitrate lands stretches along the eastern slope 

 of the coast range of barren, verdureless mountains which wall in the 

 Pacific Ocean from the northern limit of Peru to the Straits of Magel- 

 lan, upon which, for more than 2,000 miles, no rain ever falls and 

 upon which there is no living vegetation. Some of the peaks reach 

 an altitude of 4,000 or 5,000 feet above the sea level, but the usual 

 height of the range is about 2,000. The average distance from the 

 coast to the nitrate beds is about 14 miles, but man}^ of them are not 

 more than 10 miles. 



The accompanying map, p. 393, from Fuchs and De Launays, Traite 

 des Gites Mineraux, will serve to show the geographic position of the 

 deposits. 



Specimen No. 62111, U.S.N.M., show the varying character of the 

 material as mined. 



3. Nitro-Calcite. 



Nitro-calcite, or calcium nitrate, CaN20e+-«H20, is not uncommon 

 as a silky efflorescence on the floors and walls of dry limestone caverns 

 and may be extracted in considerable quantities from their residual clays 

 by a process of leaching. During the war of 1812 the clays upon the 

 floors of Mammoth Cave, Kentucky, were systematically leached and 

 the dissolved nitrate obtained by evaporation and crystallization. The 

 wooden tanks and log pipes for conducting the water are still in a 

 remarkable state of preservation, owing to the dry air of the cavern. 



The nitrous earths of Wyandotte Cave in southern Indiana, and 

 doubtless of other localities, were similarly treated during these times 

 of temporary stringency. (See Specimens Nos. 68165, 68166, U.S.N.M. 

 in cave exhibit.) 



