Art. X. On a curious substance which accompanies the native Nitre of Kentucky and of Africa.
Art. X. On a curious substance which accompanies the native Nitre of Kentucky and of Africa. Communicated in a letter to the Editor, from Samuel Brown, M. D. late of Kentucky, now of the Alabama Territory.
REMARKS.
The scientific public were several years ago laid under obligations to Dr. Brown, for a very interesting and instructive account of the nitre caverns, &c. of Kentucky, published in the Transactions of the Philosophical Society, in Philadelphia, Vol. VI., and in Bruce's Journal, Vol. I. p. 100. The following communication arose from a conversation on that subject between Dr. Brown and the Editor.
New-Haven, July 27, 1818.
Dear Sir,
I have just found the passage I referred to the other day, relative to the existence of native or sandrock nitre in the interior of Southern Africa. It is in Barrow, and not in Vaillant, as I thought when I had the pleasure of conversing with you concerning it. I am much obliged to you for recalling my attention to that curious subject, as it has brought to my recollection a fact, which I believe I omitted to mention in my memoir, (viz.) the existence of a black substance in the clay under the rocks, of a bituminous appearance and smell. This I remember to have seen in a rock-house, near the Kentucky river, where very considerable quantities of sandrock nitre had been obtained. This substance was found in masses of a few ounces weight, and in the crevices of the rocks near the basis of the side walls. The smell was not wholly bituminous, but resembled that of bitumen combined with musk. I am quite unable to account for the formation of the nitre, or the production of this black substance which sometimes accompanies it, both in Africa and America. Had I seen Mr. Barrow's travels, when I noticed the bitumen, I should certainly have paid more attention to it. But perceiving no relation between the rock nitre and the masses of this substance, my examination of it was much too superficial. I do not very well understand what Mr. Barrow means by saying, that many wagon loads of animal matter lay on the roof of the caverns in Africa. I saw no such matter on the roof of the rock-houses in Kentucky. Certainly the caverns have been the habitations of wild beasts, and great quantities of leaves, &c. have been mixed with the debris of the superincumbent rocks, but it does not seem probable, that much animal matter could be filtrated through a roof of rock, perhaps forty or fifty feet in thickness. The subject, however, is very curious, and deserves much more attention than any of us have bestowed upon it.
Extract from Barrow's Southern Africa, p. 291. New-York edition.
"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.
