OF COMMON SALT, 163 



by cattle, exists, whose presence can only be accounted for 

 by chemical action. The whole district is a mass of horn- 

 blende, quartz and felspar, shot with trap. Mr. Bruce 

 Foote, of the G-eological Survey of India, accounts for this salt 

 by chemical action. I am not sure that the Chilian salt is 

 not after all marine, but I will give here the substance 

 of M. Pissis' report on the subject. He states that the salt 

 is associated with large quantities of potassic nitrate, which 

 is not found in marine formations, and there is an entire 

 absence of stratified rocks, which are found associated with 

 ordinary rock salt. The salt deposits are on the surface of 

 the hill plateau (the Cordillera of Maricunga) at various 

 elevations up to 13,200 feet, but not in the valley beneath. 

 Marine shells are quite absent from this deposit. He argues 

 that the salt must have some independent local origin . 

 Besides sodic chloride and potassic nitrate, calcic sulphate 

 and sodic sulphate are, however, largely present. 



For the manufacture of the above salts in nature's laboratory, 

 sodium and calcium-nitrate, chlorhydric and sulphuric acids, 

 are required. The surrounding rocks are felspathic and the 

 soil is a felspathic detritus. The felspaths are composed of 

 albite, labrodite, and oligoklase. Labrodite contains a 

 large quantity of lime ; albite from 8 to 10 per cent of 

 soda ; oligoklase contains both potash and soda — here are 

 the bases. The same rocks furnish some of the required acids. 

 They contain pyrites, which may yield sulphuric acid on 

 oxidation, and trachytes, which furnish chlorine and chlo- 

 rides. The atmosphere yields nitric acid. The experiments of 

 Chloes prove that nitric acid is formed by the action of 

 alkaline carbonates in the presence of oxidizable matter. 

 Now, M. Pissis believes that all the decompositions and 

 recompositions required, resulting in the ultimate formation 

 of the salts actually found, are constantly going on, and are 

 sufficient to account for the existing salt and other deposits. 



