84 RIO NEGRO. 



tliat he considered it as fifty per cent, less valuable. 

 Hence the Cape de Verd salt is constantly import- 

 ed, and is mixed with that from these salinas. The 

 purity of the Patagonian salt, or absence from it of 

 those other saline bodies found in all sea-water, is 

 the only assignable cause for this inferiority : a 

 conclusion which no one, I think, would have sus- 

 pected, but which is supported by the fact lately 

 asceitained,* that those salts answer best for pre- 

 serving cheese which contain most of the deliques- 

 cent chlorides. 



The border of the lake is formed of mud : and 

 in this numerous large crystals of gypsum, some of 

 which are three inches long, lie embedded ; whilst 

 on the surface others of sulphate of soda lie scatter- 

 ed about. The Gauchos call the former the " Padre 

 del sal," and the latter the " Madre ;" they state 

 that these progenitive salts always occur on the 

 borders of the salinas, when the water begins to 

 evaporate. The mud is black, and has a fetid 

 odour. I could not at first imagine the cause of 

 this, but I afterwards perceived that the froth which 

 the wind drifted on shore was coloured green, as 

 if by confervEe : I attempted to cany home some 

 of this green matter, but from an accident failed. 

 Parts of the lake seen from a short distance ap- 

 peared of a reddish colour, and this perhaps was 

 owing to some infusorial animalcula. The mud in 

 many places was thrown up by numbers of some 

 kind of worm, or annelidous animal. How sur- 

 prising it is that any creatures should be able to 

 exist in brine, and that they should be crawling 

 among crystals of sulphate of soda and liine ! And 

 what becomes of these worms when, during the 

 long summer, the surface is hardened into a solid 



* Report of the Agricult. Chem. Assoc, in the Agricult. Gazette, 

 1845, p. 93. 



