SOUTHERN AFRICA. 127 
fome force to break, and the laft foot was fo folid that the fpade 
would fcarcely pierce it ; and one-fifth part of the mafs at leaft 
was pure fait in chryftals. The water now gufhed in perfedly 
clear and as fait as brine. 
Another obje(Jl of natural hiftory was difcovered about five 
miles north-weft from the fait pan. This was on the fide of a 
fmall hill down which ran a ftreamlet of chalybeate water from 
a fpring fituated about midway of the afcent. Immediately 
below the fpring the ftream ran through a chafm of five or fix 
feet deep, in the midft of a mound of black boggy earth which 
feemed to have been vomited out of the fpring. The mound was 
completely deftitute of any kind of vegetation, and fo light and 
tumefied that it would fcarcely fupport the weight of a man. 
The water was clear, but the bottom of the channel was covered 
with a deep orange-colored fediment of a gelatinous confiftence, 
void of fmell or tafte. In every part of the bog was oozing 
out a fubftance, in fome places yellow, and in others green, 
which was auftere to the tafte like that of alum. When 
expofed to the flame of a candle it fwelled out into a large 
hollow blifter, of which the external part had become a red 
friable clay, and the interior furface was coated over with a black 
glalTy pellicle. The fmell given out was at firft flightly ful- 
phureous and afterwards bituminous. Great quantities of a 
dark, red, ocraceous earth was thrown out from the bog in 
fmall heaps like mole-hills. This when taken between the 
fingers became oily and adhefive, and the color brightened to 
that of vermilion. Both the red, the green, and the yellow 
fubftances, when boiled in water, depofited a fmooth clayey 
fediment, 
