1835.] A SALT PLAIN. ' 361 



The salt is white, very hard, and compact : it occurs in 

 water-worn nodules projecting from the agglutinated sand, 

 and is associated with much gypsum. The appearance of 

 this superficial mass very closely resembled that of a country 

 after snow, before the last dirty patches are thawed. The 

 existence of this crust of a soluble substance over the 

 whole face of the country shows how extraordinarily dry 

 the climate must have been for a long period. 



At night I slept at the house of the owner of one of the 

 saltpetre mines. The country is here as unproductive as 

 near the coast ; but water, having rather a bitter and 

 brackish taste, can be procured by digging wells. The 

 well at this house was thirty-six yards deep : as scarcely 

 any rain falls, it is evident the water is not thus derived ; 

 indeed if it were, it could not fail to be as salt as brine, for 

 the whole surrounding country is incrusted with various 

 saline substances. We must therefore conclude that it per- 

 colates underground from the Cordillera, though distant 

 many leagues. In that direction there are a few small 

 villages, where the inhabitants, having more water, are 

 enabled to irrigate a little land, and raise hay, on which 

 the mules and asses, employed in carrying the saltpetre, are 

 fed. The nitrate of soda was now selling at the ship's side 

 at fourteen shillings per hundred pounds : the chief expense 

 is its transport to the sea-coast. The mine consists of a 

 hard stratum, between two and three feet thick, of the 

 nitrate mingled with a little of the sulphate of soda and 

 a good deal of common salt. It lies close beneath the 

 surface, and follows for a length of one hundred and fifty 

 miles the margin of a grand basin or plain; this, from itN 

 outline, manifestly must once have been a lake, or more 

 probably an inland arm of the sea, as may be inferred from 

 the presence of iodic salts in tlie saline stratum. The 

 surface of the plain is 3300 feet above the Pacific. 



July \^th. — We anchored in the Bay of Callao, tli 

 aport of Lima, the capital of Peru. We stayed heitt 

 \- weeks, but from the troubled stale of public affairs, I 

 tvv very little of the country. During our whole visit the 

 imate was far from being so delightful as it is generally 

 presented. A dull heavy bank of clouds constantly hung 

 or the land, so that during the first sixteen days I had 

 Illy one view of the Cordillera behind Lima. These 

 mountains, seen in stages, one above the other, through 



