140 Mr. D. Forbes's Researches on the 



In Watts' s recent and excellent ' Dictionary of Chemistry/ vol. iv. 

 p. 105, the locality is given as " Tarapaca, Northern Chile," which 

 also is the case in Dana's Mineralogie, p. 434; and both the last- 

 mentioned authors give an analysis of Chilian nitratine by Hoch- 

 stetter*. Besides this analysis, all the works above, referred to 

 cite analyses of nitratine by Hayes and Lecanu, which analyses 

 are also given by Rammelsberg in his Handbuch der Miner alchemie, 

 p. 247, but he groups them all together in respect to locality, 

 simply stating them to be all "aus dem Distrikt Atacama in 

 Bolivia," although it is quite certain that no one of the specimens 

 referred to came from any part of the Bolivian desert of Atacama. 



Since the author's visits to this part of the Pacific coast of South 

 America in 1857 and 1859, the results of which are published in a 

 report on the Geology of Bolivia and Southern Peru, communi- 

 cated to the Geological Society of London, Nov. 21, 1860 1, a 

 second exploration, made in 1863, has fully confirmed his pre- 

 vious observations, and the views expressed in that report as to 

 the origin of these vast deposits of nitrate of soda. 



The workings for the crude nitrate of soda are opened upon 

 the inclined grounds which ascend gently from the arid salt 

 valleys and plains which had, as it were, been bays and indenta- 

 tions in the eastern coast-line of the Great Plain or Pampa de 

 Tarn aru gal when that was a sea, which, at an elevation of about 

 3250 feet above the level of the Pacific Ocean, extends over a 

 large portion of the Province of Tarapaca in the department of 

 Moquegua in Peru. 



These deposits are known to exist from about latitude 19° S. 

 extending to latitude 21° 30' S., where the river Loa forms the 

 southern boundary between the Republics of Peru and Bolivia. 

 More recent explorations in 1860 have showed that some de- 

 posits existed also to the south of the river Loa in Bolivian 

 territory, and were subsequently worked on a small scale, the 

 produce being shipped from the harbour of Tocopilla on the 

 coast of Bolivia. It is, however, stated that they were soon 

 abandoned as unprofitable. 



The range of saliferous country runs parallel to the coast, at 

 an average elevation of from 2500 to 3500 feet above the level 



* The author has referred to the Annalen der Chemie und Pharmacie, 

 vol. xlv. p. 340,for the original of this analysis, and finds it was by Hofstetter, 

 not Hochstetter, and that the mineral is there described as " natiirliches, 

 aus Perou." As this chemist is understood never to have been in the dis- 

 trict, and the analysis corresponds to the commercial nitratine, differing 

 greatly from all analyses of natural nitrate, it seems most probable that the 

 analysis in question was made upon the commercial nitrate as shipped from 

 Iquique, and which is generally supposed to be a natural product, although 

 in reality it has been subjected to a crude process of refining. 



t Quarterly Journal of the Geological Society of London, vol. xvii. 



