352 



On Nitrate of Soda. 



holds on its course to the westward, while no accidental breeze 

 brings them back." 



Striking inland from Iquique, you first ascend a slope of loose 

 white sand 1000 feet high, and then cross "a low mountain 

 range covered with large angular pieces of rock to which ages of 

 solar heat have given a calcined appearance, some having crumbled 

 into powder. Here is much salt of a variety called clinkers. 

 They have at a distance the appearance of bones, and the scene 

 is one of absolute sterility. Everything is of a dull brown colour, 

 except the blueish range of the Andes in the distance covered 

 with snow." The only vegetation, Darwin had told us, besides 

 a few cacti, is lichen of two kinds lying unattached on the sand, 

 and tinging it in places with a yellow hue ; the projecting lumps 

 of salt, he said, give the appearance of a country after snow before 

 the last dirty patches have thawed. 



Having traversed this range (here about 10 miles wide), we 

 reach a great plain, the Pampa of Tamarugal ; but though a flat 

 tract, it is as high as Skiddaw, being 3000 feet above the sea- 

 level. It stretches north and south at the foot of the gigantic 

 Andes for 80 miles ; and along its western border, therefore the 

 side nearest the sea, lie the grounds we are in quest of. They 

 are for the first time described accurately by Mr. Bollaert, and, as 

 the details are important, these must be given in his own words : — 



" The principal deposits of nitrate of soda yet known are found on the 

 western side of the Pampa de Tamarugal, commencing immediately where 

 the level plain ceases, and on the sides of some of the ravines running from 

 the Pampa towards the coast, and in some of the hollows of the mountains. 

 The nitrate has not been found nearer to the coast than 18 miles, and looks as 

 if it gradually transferred itself into salt as it approached the coast. The 

 oficinas, or refining works, are divided into northern and southern salitres ; 

 the old salitres being about the centre of the former, and La Nueva Noria that 

 of the latter ; there are in all about 100 oficinas. 



" The nitrate deposits commence about Tiliviche, and extend S. near to 

 Quilliagua, with interruptions of deposits of common salt. The nitrate caliche 

 grounds vary in breadth ; the average may be 500 yards, and in places 7 to 

 8 feet thick, and sometimes quite pure. In the ravines and hollows before 

 mentioned the nitrate is found on their shelving sides ; the hollows look like 

 dried-up lakes, and are covered with salt 2 to 3 feet thick, and on the margins 

 there is nitrate of soda, ofttimes going down to some depth : in others there is 

 a hard crust upon it, occasionally 4 feet thick. The nitrate caliche found 

 under this crust is in thin layers, and so solid and pure as to be sought for, 

 although the expense of blasting is very great. 



" There are several varieties of the nitrate of soda caliche, the following 

 being the principal : — 



1. White compact, containing 64 per cent. 



" 2. Yellow, occasioned by salts of iodine, 70 per cent. 



" 3. Grey compact, containing a little iron and a trace of iodine, 46 per 

 cent. 



" 4. Grey crystalline, the most abundant variety,' contains from 20 to 85 

 per cent., affording traces of iodine, with 1 to 8 per cent, of earthy matter. 

 " 5. White crystalline : this resembles the refined nitrate. Ail these con- 



