34 



TRANSACTIONS OF THE 



cold water, until the water came off tasteless, and then 

 evaporating the lixivium to dryness, the earth was found 

 to contain 16.25 of soluble salts. The weight lost by 

 the earth during lixiviation, was to a grain equal to the 

 weight of the salts obtained. In another portion of the 

 earth, we found the salts equal to 18.7 per cent. From 

 which it is probable that in the natural bed of the earth, 

 the soluble salts are very unequally diffused. 



A considerable quantity of the earth was now washed ; 

 the lixivium filtered, and a strong solution of the salts 

 made, which was subjected to the following experiments : 



1. The ferrocynate of potassa added to a portion of 

 the solution of the salts gave a deep blue precipitate. 

 The supernatant liquid was decanted, and the precipi- 

 tate dried, and formed with alumina into a cake of 

 Prussian blue. 



2. The tincture of galls dropped into the solution 

 produced a dark bluish black color. These two ex- 

 periments undoubtedly indicate the presence of the 

 peroxide of iron, 



3. On adding to the solution of the salts, the car- 

 bonate of potassa, carbonic acid escaped, and a grayish 

 green deposit was formed. This was separated by a 

 filter ; its color was reddish externally, but greenish 

 beneath the surface ; when dry it presented a dark 

 brown tint. The greenish gray color was no doubt 

 produced by the presence of protoxide of iron. The 

 above appearances also indicate the peroxide and prot- 

 oxide of iron united to an acid. 



4. On treating a clear solution of the salts with the 



