148 Dr. Brown on the Nitre, §c. 
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 
é . 
dition. 
« About 12 miles to the eastward of the wells, (Hepatic 
wells,) in a kloof of the mountain, we found a considerable 
quantity of native nifre. 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 @ 
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 mire 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 a 
article of export. There was also in the same cave, running 
down the sides of the rock, a black substance, that was apP* 
rently bituminous. The peasants called it the urine of the 
das. The dung of this gregarious animal was lying up?” 6! 
roof of the cavern to the amount of many wagon loads. + 
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 Ags 
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 ce inly 
are highly deserving of the attention of naturalists. : 
In Philadelphia you may have an opportunity of sells 
some small specimens of the sandrock, containing nitre, noW 
in the cabinet of the Philosophical Society. 
4 
