Aug. 1833. GLAUBER SALTS. 91 



-b 



been tw^enty hours without water, and only part of tlie time 

 under a hot sun, yet the thirst rendered me very weak. 

 How people surviA^e two or three days under such circum- 

 stances, I cannot imagine : at the same time, I must con- 

 fess that my guide did not suffer at all, and was asto- 

 nished that one day's deprivation should be so troublesome 

 to me. 



I have several times alluded to the surface of the ground 

 being incrusted with salt. This phenomenon is quite dif- 

 ferent from that of the sahnas, and much more extraordinary. 

 In many parts of South America, wherever the chmate is 

 moderately dry, these incrustations occur; but I have no- 

 where seen them so abundant as near Bahia Blanca. Tlie 

 salt here consists of a large proportion of stdphate of soda 

 mixed with a very little of the common muriate. As long 

 as the ground remains moist in these salitrales (as the 

 Spaniards improperly call them, mistaking this substance 

 for saltpetre), nothing is to be seen but an extensive plain 

 composed of a black, muddy soil, supporting scattered 

 tufts of succulent plants. I was therefore much surprised, 

 after a week's hot weather, when I first saw square miles of 

 country, that I had previously ridden over in the former 

 condition, white, as if from a slight fall of snow which the 

 wind had heaped up into partial drifts. This latter appear- 

 ance is chiefly due to the tendency which the salt has to 

 crystalhze, like hoar-frost, round the blades of grass, stumps 

 of wood, or on the top of the broken ground, in heu of the 

 bottoms of the puddles of water. The sahnas, as a general 

 rule, occur in depressions on the more elevated plains ; the 

 salitrales, either on level tracts elevated a few feet above 

 the level of the sea, and appearing as if lately inundated, or 

 on alluvial land bordering rivers. In this latter case, 

 although I am not absolutely certain, I have strong reasons 

 for believing that the salt is often removed by the waters of 

 the river, and is again reproduced. Several circumstances 

 incline me to think that the black, muddy soil, generates the 

 sulphate of soda. The whole phenomenon is well worthy the 



