On Nitrate of Soda. 



351 



hope to show, of future reduction. For the ohl nitre is either pre- 

 pared artificially, or is gathered as it grows in a light efflorescence 

 on the ground's surface in Spain, Egypt, and India ; but the 

 cubic nitre of Peru is found ready piled in beds several feet thick, 

 throughout a long tract of country. In order to ascertain how 

 far the sources of supply may allow a further diminution of price, 

 I have carefully consulted all the authentic statements within my 

 reach. The accounts of this nitre-bearing district have been 

 hitherto rather vague, for the country was almost unknown : but 

 at last we have an authentic description* of this extraordinary 

 region from an eye-witness, Mr. Bollaert, who, having resided 

 there many years, has minutely depicted it in a memoir and survey 

 just published by the Geographical Society. 



Peru is well known to be a narrow tract looking down west- 

 ward on the Pacific, and up to the lofty chain of the Andes east- 

 ward. Of this strip, many hundred miles long, the most arid 

 portion is the southern, and here is the province of Tarapaca, of 

 which the chief port is Iquique. This port is guarded by an 

 island once covered with guano, whence that manure was formerly 

 called Guano de Iquique, though many islands equally rich, but 

 less celebrated, stretch northward along the desert shore. .Mr. 

 Bollaert tells us that " there is neither wood, water, nor vegetation 

 here. ]Most of the water is brought by sea from Pisagua, 45 

 miles to the north. During three years' residence at Iquique he 

 only once saw a slight shower of rain, barely sufficient to lay the 

 dust." This marvellous dryness, I may observe, has been of late 

 thoroughly explained by Meteorology, which has at last laid down 

 some general laws for the differences of climate. One of these 

 laws is, that wind rising from the sea-level, and passing over 

 a mountain ridge, becomes colder, is capable therefore of con- 

 taining less invisible moisture, parts with that moisture as rain, 

 and descends on the other side of the range dried like a sponge that 

 has been squeezed. The Andes, once supposed to be the loftiest 

 ridge in the world, dry the air thoroughly. The Himalayas, now 

 found to be higher, for the same reason render Thibet a pre-emi- 

 nently arid country. But Thibet receives other gales besides 

 those from the south over the Himalayas. Peru is within the 

 range of the trade-winds, which blow all the year round in one 

 changeless sweep across the Southern Atlantic, and so pass the 

 Andes. Hence, as Mons. Guiot f says, in his 'Physical Geo- 

 graphy,' the coast of Peru, from the Equator to Chili, is scarcely 

 ever refreshed by the rains of the ocean. Deprived of the vapours 

 of the Atlantic by the chain of the Andes, these countries behold 

 the vapours of the Pacific flit away with the trade-wind that 



* Journal of the Eoyal Geographical Society, vol. xxi. p. 99. 

 t Guiot's Earth and Man, or Physical Geography, p. 12S. 



