66 EIO NEGRO. [chap, iv 



lized in great cubes, and is remarkably pure : Mr. Trenham Eeeks 

 has kindly analyzed some for me, and he finds in it only 0*26 of 

 gypsum and 0'22 of earthy matter. It is a singular fact, that it 

 does not serve so well for preserving meat as sea-salt from the 

 Cape de Verd islands ; and a merchant at Buenos Ayres told me 

 that he considered it as fifty per cent, less valuable. Hence the 

 Cape de Verd salt is constantly imported, 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 suspected, but which is supported by 

 the fact lately ascertained,* that those salts answer best for pre- 

 serving cheese which contain most of the deliquescent chlorides. 

 The border of the lake is formed of mud : and in this nume- 

 rous large crystals of gypsum, some of which are three inches 

 long, lie embedded ; whilst on the surface others of sulphate of 

 soda lie scattered 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 confervas : I attempted to carry 

 home some of this green matter, but from an accident failed. 

 Parts of the lake seen from a short distance appeared 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 surprising- 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 lime ! And 

 what becomes of these worms when, during the long summer, the 

 surface is hardened into a solid layer of salt ? Flamingoes in 

 considerable numbers inhabit this lake, and breed here ; through- 

 out Patagonia, in Northern Chile, and at the Galapagos Islands, 

 I met with these birds wherever there were lakes of brine. I 

 saw them here wading about in search of food probably for the 

 worms which burrow in the mud ; and these latter probably feed 



* Report of the Agricult. Chem. Assoc, in the Agricult. Gazette, 1845, 



r- 93. 



