Geological and Miscellaneous Notice of Tarapaca. 7 



longitude, although it has been frequently mentioned by travellers 

 as abundant in other parts of the coast. This error has probably 

 arisen from the general use of the term sallitre, which is applied 

 alike to saltpetre and other salts. 



The nitrate of soda of Tarapaca affords employment for a large 

 part of the inhabitants of the province. In 1837 one hundred 

 and fifty thousand quintals were shipped from the port of Iqui- 

 que ; of this, about two thirds went to England, and nearly one 

 third to France. Its recent introduction as a manure will proba- 

 bly greatly increase the demand for it in foreign countries. 



The process of refining, through which the crude salt passes 

 before it is transported to the ports for exportation, is rude and 

 simple. The operation is conducted generally by Indians, under 

 the direction of a Spanish major-domo. Each officina or work- 

 ing place, consists of a few rude huts, the walls of which are 

 constructed of cakes of salt, cemented together with the mixed 

 marl and salt obtained from the kettles in use for refining, the 

 roofs being formed of mats, supported by rafters of Cactus. 



All the work of refining is conducted in the open air. The 

 apparatus consists of a few copper kettles, of the capacity of fifty 

 gallons each, set within walls formed of cakes of salt, and shal- 

 low oblong square vats for crystallizing. The salt, as blasted 

 from the bed, which is always near to the officina, is carried in 

 bags on the backs of laborers near to the kettles, where women 

 and children are employed in breaking it into fragments of the 

 size of hens' eggs. About two thirds of each kettle being filled 

 with the broken salt, and water added, a strong fire is maintained 

 until the water becomes saturated, when it is dipped into tubs 

 to settle, and from thence transferred while hot to the crystalli- 

 zers. The undissolved portion which remains, consisting prin- 

 cipally of chloride of sodium and earthy matter, is thrown aside 

 as worthless, although frequently not more than one half of the 

 nitrate has been separated, the same relative proportion of crude 

 salt being at all times used, without regard to its quality. 



Aside from the want of economy displayed in the refining pro- 

 cess, the affairs of the officinas are well conducted. Each branch 

 of the operation, from the breaking the salt from the bed up to 

 the time when it is placed on board vessels for exportation, is 

 conducted by a distinct class of laborers, who receive for their 

 work a fixed sum on each quintal of the refined salt produced. 



