1906.] 



The Nitrate of Soda Deposits. 



473 



The only source from which natural nitrate of soda is at 

 present obtained is from the deposits in the northern part of the 

 Republic of Chili in the Provinces of Tara- 



The Nitrate of p^^^ ^^^^ Atacama. The district is prac- 

 Soda Deposits. ^. . , ^ , \, 



tically a ramless one, from three to rive 



years sometimes passing without rain, and even when it falls it 

 is in hardly sufficient quantities to penetrate the topmost layer 

 of soil. This fact has an important bearing on the possibility 

 of discovering similar accumulations elsewhere, as nitrate of 

 soda is especially soluble in water, and deposits of this character 

 could only continue to exist in a region such as this. 



The nitrate district is a desolate waste, bearing not a trace 

 of vegetation. The surface is usually composed of sand and 

 gypsum, called " cJiucha'' beneath which lies a layer of earth and 

 detritus called costra," some 3 ft. to 12 ft. thick. Beneath this 

 lies the nitrate of soda to a depth of from i ft. to 12 ft. A large 

 number of different salts are found in the " caliche," as the 

 nitrate deposits are called, and in the upper layers. The nitrate 

 is obtained by boring through the upper layers and introducing 

 charges of gunpowder. This is fired by means of a slow match 

 and the explosion enables a considerable area of the " caliche " 

 to be reached. It is then loaded into wagons, and conveyed 

 by a light railway to the factory. Here the natural salts 

 are purified by crystallization to produce commercial nitrate 

 of soda containing 95 per cent, nitrate, having 15^ per cent, 

 of nitrogen. 



The export trade dates from about 1830. In 1840-44 the 

 average quantity sent abroad annually was 14,640 tons, and by 

 1870-74 it had increased to 219,125 tons. During the war of 

 1879-80 between Chili and Peru the export declined; when, 

 however, Chili took possession of the nitrate territory, a very 

 marked growth in the export took place, which averaged 

 444,185 tons in 1880-84, with the result that the market was 

 overstocked and prices fell. In consequence the producers 

 formed in 1884 a combination for the purpose of regulating the 

 production. This lasted till 1887, and further attempts were 

 made in 1891 and 1896, but failed from a lack of agreement 

 amongst the producers. Increasing competition, however, led 

 finally in 1900 to the formation of the " Nitrate Syndicate " for 



