266 TRAVELS IN 
emery-sand. The soil of the adjacent country, and of the 
banks of the river, was a firm bluish clay. On every side of 
the wells, and not many yards distant from them, were several; 
circular bogs puffed up to the height of four or five feet above 
the common surface. These were highly elastic, and gave out 
springs of water that was cold, and clear, and tasteless. The 
waters of these hepatic wells are said to have been found 
very efiicacious in healing bruises and sprains,, and favorable 
also to rheumatic complaints, to which, from the great change- 
ableness of the climate, the peasantry are very subject. 
About twelve miles to the westward of the wells, iu a kloof 
of a detached mountain, we found a considerable quantity of 
native nitre. It was in a cavern similar to those used by Bos- 
jesmans for their winter habitations, and in which they make 
the drawings above noticed. The under surface of the pro- 
jecting stratum of calcareous sand-stone, and the sides that 
supported it, were encrusted with a coating of clear white salt- 
petre, 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 burned completely away without leaving any 
residuum ; and, if dissolved in water, and this evaporated, 
crystals of pure prismatic nitre were obtained. This salt, in 
the same state, is to be met with under the sand-stone strata 
of many of the mountains of Africa ; but perhaps not in suf- 
ficient quantities to be collected as an object of commerce. 
There was also in the same cave, running dov/n the sides of 
the rock, a black substance that apparently was bituminous : 
the peasantry called it the urine of the Das. The dung of 
this gregarious animal was lying upon the roof of the cavern 
