NATURAL HISTORY OF ATRICA, 
having been found in the valley of Egarement, 
associated with rock salt. 
4. Salt. 
This mineral occurs in vast quantities in North- 
ern Africa, on both sides of the Atlas mountains. 
Mr Horneman, in his journey from Cairo to Um- 
mesogeir, discovered a plain on a limestone range, 
which bounds the desert of Libya to the north, con- 
sisting of a mass of rock salt, spread over so large a 
tract of surface, that in one direction no eye could 
reach its termination, and its width he computed 
at several miles. To the south-east of Abyssinia 
there is a plain of salt four days' journey across, 
whence all that country is supplied. In the val- 
ley of Egarement there are beds of salt resting 
upon gypsum. At Tegazza, and in several other 
places in Sahara, large beds of very pure rock 
salt occur vmder strata of different kinds of solid 
rock ; and beds of salt appear in Darfur. Salt is 
also obtained in quantity from salt lakes of Dom- 
boo, from similar lakes in Southern Africa ; and it 
is remarked that beds of rock salt occur under 
strata of sandstone in Southern Africa, and in 
beds in Madagascar. 
5. Coal. 
Hitherto scarcely any traces of coal have been 
met with in Africa. The only instance I find re^ 
