24 NATURAL HOT BATH. 



with filling at the spring two bottles, which were sent, 

 along with the nourishing milk of the tree called polo de 

 vaca, to MM. Fourcroy and Vauquelin, by the way of 

 Poriio Cabello and the Havannah. This purity in hot 

 waters issuing immediately from granite mountains is in 

 Europe, as well as in the New Continent, a most curious 

 phenomenon.* How can we explain the origin of the 

 sulphuretted hydrogen? It cannot proceed from the de- 

 composition of sulphurets of iron, or pyritic strata. Is it 

 owing to sulphurets of calcium, of magnesium, or other 

 earthy metalloids, contained in the interior of our planet, 

 under its rocky and oxidated crust ? 



In the ravine of the hot waters of Mariara, amidst little 

 funnels, the temperature of which rises from 56 to 59, two 

 species of aquatic plants vegetate ; the one is membrana- 

 ceous, and contains bubbles of air; the other has parallel 

 fibres. The first much resembles the Ulva labyrinthiformis 

 of Vandelli, which the thermal waters of Europe furnish. 

 At the island of Amsterdam, tufts of lycopodium and mar- 

 chantia have been seen in places where the heat of the soil 

 was far greater : such is the effect of an habitual stimulus 

 on the organs of plants. The waters of Mariara contain no 

 aquatic insects. Erogs are found in them, which, being 

 probably chased by serpents, have leaped into the funnels, 

 and there perished. 



South of the ravine, in the plain extending towards the 

 shore of the lake, another sulphureous spring gushes out, 

 less hot and less impregnated with gas. The crevice whence 

 this water issues is six toises higher than the funnel just 

 described. The thermometer did not rise in the crevice 

 above 42. The water is collected in a basin surrounded by 

 large trees ; it is nearly circular, from fifteen to eighteen feet 

 diameter, and three feet deep. The slaves throw themselves 

 into this bath at the end of the day, when covered with 

 dust, after having worked in the neighbouring fields of in- 

 digo and sugar-cane. Though the water of this bath (bano) 

 is habitually from 12 to 14 hotter than the air, the negroes 

 call it refreshing ; because in the torrid zone this term is 



* Warm springs equally pure are found issuing from the granites 

 of Portugal, and those of Cantal. In Italy, the Pisciarelli of the lake 

 Agnano have a temperature equal to 93. Are these pure waters pro- 

 duced by condensed vapours ? 



