66 RIO NEGRO. [cHaP. IV 
lized in great cubes, and isremarkably pure: Mr. Trenham Reeks 
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 confervee: 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 Avricult Chem. Assoc. in the Agricult. Gazette, 1845, 
y. 98. 
