489 



from south to north, either from Valencia and 

 the vallies of Aragua, to Burburata and Turia- 

 mo, or from Caraccas to La Guayra. The hot 

 sources * issue from those flanks, those of Las 



* See above, Vol. ill, p. 199 j Vol. iv, p. 52, 107, 190, 

 and 271. The other hot sources of the Cordillera of the 

 shore, are those of S. Juan, Provisor, Brigantin, the gulph 

 pf Cariaco, Cumacatar, and Irapa. MM. Rivero and Bous- 

 singault, who visited the thermal waters of Mariara, in Fe- 

 bruary, 1823, during their journey from Caraccas to Santa 

 Fe de Bogota, found their maximum to be 64° cent. I found 

 it at the same season, only 59*2°. Has the great earthquake 

 of the 26th of March, 1812, had an influence on the tempe- 

 rature of these sources ? The able chemists whom I have 

 just mentioned, were struck like myself, with the great pu^ 

 rjty of the hot waters that issue from the primitive rocks of 

 the basin of Aragua. ft Those, of Onoto, which flow at the 

 height of 360 toises above the level of the sea, have no smell 

 of sulphurated hydrogen - y they are without taste, and can- 

 not be precipitated, either by nitrate of silver or any reac- 

 tive. When evaporated, they have an inappreciable residue, 

 which consists of a little silica and a trace of alcali ; their 

 temperature is only 44*5°, and the bubbles of air which are 

 tlisengaged intermittingly, are at Onoto, as well as in the 

 thermal waters of Mariara, of pure gaz azote (See above, 

 Vol. vi, p. 80). The waters of Mariara (244 toises) have a 

 faint smell of sulphurated hydrogen - } they leave by evapora- 

 tion a slight residuum, that yields carbonic acid, sulphuric 

 acid, soda, magnesia, and lime. The quantities are so small 

 that the water is altogether without taste." (Letter of M. 

 Boussingault to M. de Humboldt, in the Annates de.Phys. 

 et de Chimie, torn, xxvi, p. 81.) During my journeys I found 

 the source of the Comangillas only, (near Guanaxuato in 



