169 



whole body of the thermal waters forms a seo 

 tion of only twenty-six square inches. This is 

 considerably augmented in the rainy season ; 

 the rivulet is then transformed into a torrent, 

 and it's heat diminishes ; for it appears, that 

 the hot springs themselves are subject only to 

 imperceptible variations. All these springs are 

 slightly impregnated with sulphuretted hydrogen 

 gas *. The smell of rotten eggs, peculiar to this 

 gas, can be perceived only by approaching very 

 near the springs. In one of these wells only, 

 the temperature of which is 56*2°, an extrica- 

 tion of bubbles of air occurs, and takes place at 

 nearly regular intervals of two or three minutes. 

 I observed, that these bubbles constantly rose 

 from the same points, which are four in number ; 

 and that it was not possible to change the 

 places^ from which the gas is emitted, by stir- 

 ring the bottom of the basin with a stick. These 

 places correspond no doubt to holes or fissures 

 in the gneiss ; and indeed when the bubbles rise 

 from one of the apertures, the emission of gas 

 follows instantly from the other three. I could 

 not succeed in inflaming the small quantities of 

 gas, that rise above the thermal waters ; or those 

 which I had collected in a glass vial held over 

 the springs, an operation that excited in me a 

 nausea, caused less by the smell of the gas, than 



* Hy'-rosiilphiiric acid. 



