148 Dr. Brown on the Nitre, fyc. 



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. JVew-York 

 edition. 



" About !2 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 appa- 

 rently 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 5androck, containing nitre, now 

 in the cabinet of the Philosophical Society. 



