152 On the Hot Springs of the Cordilleras of the Andes. 



new degree of importance, as these salts must then be considered 

 as the soluble products which exist or are formed in the interior 

 of volcanos. Such are the various considerations which induced 

 M. Boussingault to undertake the analysis of the hot springs he 

 has met with during his travels, and the memoir read to the 

 Academy presents the results. The conclusion drawn from the 

 numerous analyses performed is, that the gases accompanying 

 the hot springs, which have their sources near volcanos, are 

 identical with those of the craters of the same volcanos, viz. car- 

 bonic acid and sulphuretted hydrogen gases. It is then pro- 

 bable that the hot waters of the trachytic formation of the equator 

 owe their elevated temperature to subterranean fire, and it is 

 equally natural to believe, that the salts dissolved in these waters 

 are derived from the interior of volcanos. Before terminating 

 this memoir, the author examines the question as to the varia- 

 tion of temperature of the hot springs he investigated. In 1800, 

 M. de Humboldt found the temperature of the Mariara spring 

 to be59°.3cent. In 1823, M. Boussingault and M. Rivero 

 found the thermometer in the same spring rise to 64j° cent, A 

 difference so considerable, viz. of 5°.3 cent., cannot be attributed 

 to an error in the instrument, especially as the thermometrical 

 observations made by those gentlemen at La Guayra and Ca- 

 raccas accord perfectly with those made in the same towns by 

 M. de Humboldt. It is more to be feared that as the spring of 

 Mariara forms a considerable stream, the observations may not 

 have been made precisely at the same point, although in general 

 an observer who determines the temperature of a hot spring en- 

 deavours to find the spot where the hot water is hottest. But 

 the objections which can be raised to the observations made at 

 the Mariara spring are quite inapplicable to those made at the 

 spring of Las Triricheras, near Puerto Cahello. At Las Trin- 

 cheras, the water issues from two basins which lie close one to 

 the other, and are hollowed in granite. The larger basin has a 

 capacity of about two cubic feet. M. de Humboldt gives 90° 

 cent, as the temperature of the water of Las Trincheras. 

 Twenty-three years later, Messrs Boussingault and Rivero 

 found the temperature of the water in one basin to be 92°.2 

 cent., and that of the water of the other 97° cent. Their ob- 

 servations, like those of M. de Humboldt, were made in the 



