The ferruginous waters are stated by Mr. Rivero, on the authority of Haenk, and of Dr. Vargas of Arequipa, to be tonic, deobstruent, laxative, diuretic, &c.; and, therefore, well calculated to remove general debility, certain forms of hypochondriasis, dyspepsia, and weakness consequent on debauchery. THE SULPHUROUS WATER. The jets (los ojos) of this water, as we formerly noticed, are placed above the ferruginous baths, situated in a narrow part formed by the trachyte rock on one hand, and on the opposite side by the _gres_, or sandy soil, which furnishes the carbonate of soda. An oblique fissure, extending to the base of the trachyte rock, serves as a conduit to this thermal water, which unites itself with that which flows from the bottom of the bath named Tigre. A short way from this jet there are others which flow from other clefts, at almost the same degree of temperature. It is observed that the source of these waters is at some distance in the interior of the rock, and, according to my notions, they hold communication with the _crater_, which emits sulphurous vapours, situated a few paces from the water underneath the very house where the sick repose. With respect to the water, having filled a small well situated at the base of the rock where people drink from, the chief object is to have it conducted to the bathing-pits, or basins. The superfluous water not needed for the baths flows out from them by a small channel; and it goes to join the rivulet, which passes within three yards of the bathing apartment. The sulphurous water flows out in good quantity, making a peculiar noise, and emitting a smell of sulphuretted hydrogen gas, like that of rotten eggs; which is perceptible at the distance of many paces from the place, when the winds are from the east and west. The disengagement of carbonic acid gas occasions the noise alluded to, through the innumerable bubbles which rise on the surface; and at the same time it occasions a shower of aqueous particles, mixed with sulphuretted hydrogen and carbonic acid gas; its colour is whitish, transparent; and on the walls and canals of the baths, it leaves a whitish substance, somewhat dirty, very fine, which when examined proves to be impure sulphur; its taste is at the same time sweetish and acidulated, but it leaves on the palate the taste of rotten eggs.