Mineralogy of South America. 139 



closely correspondingto the formula of Epsomite,MgO SO 3 -f 7HO, 

 which by calculation requires — 



Water 51 '21 



Sulphuric acid . . 32-53 

 Magnesia . , . 16*26 



100-00 



Nitratine. — Notwithstanding that the exploration of nitratine 

 or nitrate of soda has for many years formed one of the most ex- 

 tensive and important branches of Peruvian industry, the infor- 

 mation published in the works of different chemists and minera- 

 logists as to its occurrence and formation appears to be extremely 

 vague, while at the same time singularly confused views are given 

 as to the geographical position of the deposits themselves. 



One very evident source of this confusion is due to the general 

 use of the name Chile saltpetre in commerce; this name having 

 arisen at the commencement of the trade in this article, from the 

 fact of the ships in which it was exported from Peru to Europe 

 having been chartered and freighted by the merchants of Valpa- 

 raiso in Chile. The name is both misleading and entirely inap- 

 propriate, as there are no available deposits of nitrate of soda 

 known in any part of the Chilian territory. With the exception 

 of some more recently discovered deposits on the coast of Bolivia 

 to the south of the river Loa, which forms the line of frontier 

 between that country and Peru, no workable deposits of nitrate of 

 soda are known in any part of South America beyond the limits 

 of the province of Tarapaca, in the department of Moquegua in 

 Peru. 



These remarks will help to explain some of the statements 

 made under this head in various mineralogical and chemical 

 works. In Ure's { Dictionary of Arts and Manufactures/ vol. hi. 

 p. 726, nitrate of soda is stated to be " found native in immense 

 quantities in Chile/ 5 In Naumann's Mineralogie, p. 216, it is 

 described as occurring " in Thonlagern bei Iquique und Tarapaca 

 ira Department Arequiba in Bolivia"*. In Brooke and Miller's 

 •"Mineralogy/ p. 61, the localities given are "Desert of Atacama/' 

 and " Tarapaca in Peru near the frontier of Chile." Again, in 

 Burat's Mineralogie applique, p. 243, the locality is given as 

 " principalement aux environs (P Arica et d'lquique sur les cotes 

 de Perou et de la Bolivie." Both Iquique and Arica are ports 

 on the Peruvian coast ; but notwithstanding some searches were 

 a few years back made for nitrate of soda on the coast near Arica, 

 no nitrate of soda has ever been found anywhere near that town. 



* It must be remembered that Iquique is the chief town of the province 

 of Tarapaca in the department of Moquegua, Peru, and that Ariquipa is the 

 name of a city and department in Peru still further north. 



