266 



under every zone, it is not less uncertain, whe-* 

 ther the proportion between the muriat of soda, 

 the muriat and sulphat of magnesia, and the 

 sulphat and carbonat of lime be equally inva- 

 riable *. 



After having examined the salt works, and 

 terminated our geodesical operations, we de- 

 parted at the decline of day to sleep at an Indian 

 hut, at some miles distance, near the ruins of 

 the castle of Araya. We were preceded by our 

 instruments and provision ; for fatigued by the 

 excessive heat of the air, and the reverberation 

 of the soil, we felt no appetite in those climates, 

 except in the morning, or in the cool of the 

 evening. Directing our course toward the 

 south, we traversed first the plain covered with 

 muriatiferous clay, and stripped of vegetation ; 

 then two chains of hills of sandstone, between 



seawater (from 0*024 to 0*028) reminds us of the still greater 

 uniformity, with which the oxygen is diffused throughout the 

 aerial ocean. In both of these elements, the currents establish 

 and preserve the equilibrium between the parts dissolved or 

 mingled with each other. (Bayly and Cook, Original Observ., 

 p. 345.) 



* Lavoisier found, that in the waters of tbe sea, near 

 Dieppe, the quantity of muriat of soda is to that of the other 

 salts as 2*36 is to 1. According to Messrs. Bouillon-Lagrange 

 and Vogel, this proportion is as 2*60 to 1 . See the judi- ' 

 cious observations of Dr. Thomson, in his Chemistry, t. vi, 

 p. 346—457 (Henry, Phil. Trans., 1810, p. 97 and 122 ; 

 and Annales de Ch£mie, t. lxxxvii, p 193—^208.) 



