"About 12 miles to the eastward of the wells, (Hepatic wells,) in a kloof of the mountain, we found a considerable quantity of _native nitre_. It was in a cavern similar to those used by the Bosgesmans for their winter habitations, and in which they used to make the drawings above mentioned. The _under surface_ of the projecting stratum of calcareous stone, and the sides that supported it, were incrusted with a coating of _clear, white saltpetre_, that came off in flakes, from a quarter of an inch to an inch or more in thickness. The fracture resembled that of refined sugar, it burnt completely away without leaving any residuum; and if dissolved in water, and thus evaporated, crystals of _pure prismatic nitre_ were obtained. This salt, in the _same_ state, is to be met with _under_ the sandstone strata of _many_ of the mountains of Africa; but, perhaps, not in sufficient quantities to be employed as an article of export. There was also in the same cave, running down the sides of the rock, a black substance, that was apparently bituminous. The peasants called it the urine of the das. The dung of this gregarious animal was lying upon the roof of the cavern to the amount of many wagon loads. The putrid animal matter, filtrating through the rock, contributed, no doubt, to the formation of the nitre. The Hepatic wells and the native nitre rocks were in the division of Agster Sneuwberg, which joins the Tacka to the southwest." Should I ever visit Kentucky again, I hope that I shall be able to give a better account of these caverns, which certainly are highly deserving of the attention of naturalists. In Philadelphia you may have an opportunity of seeing some small specimens of the sandrock, containing nitre, now in the cabinet of the Philosophical Society. BOTANY. ART. XI. _Descriptions of species of Sponges observed on the shores of Long-Island. By_ C. S. RAFINESQUE, _Esq._ The sponges are one of the most singular productions of nature; and, even to this time, naturalists are divided in opinion respecting their real rank in the scale of organized beings. Some believe that they are animals, belonging to the class of polyps, next to the genus of _alcyonium_, while many contend that they are not animals, but plants, of the tribe of _fuci_, or marine vegetables. I am inclined to adopt this latter opinion, since in all those which I have seen, in Europe and America, no perceptible motion nor sensibility was to be discerned in any stage of their existence; and those who have acknowledged their animality, bring no stronger proof thereof than an occasional slight shrinking under the hand, and an animal smell, which are common to some marine plants.