i88 TRAVELS IN AFRICA, 
vicinity of this fpring is remarkable for the produdion of natron^ 
which fubftance appears under different circumftances, and is 
of different quality from that of Terane. It is very white and 
folid ; and on immerfion in water becomes hot, and difchargea 
a great portion of its air. 
Small quantities of it are carried by the jelabs to Egypt, 
where it is fold at a high price, and is ufed principally in mak- 
ing fnuff. The water found at this place is very unpalatable, 
being brackifh. 
A troop of the natives of Zeghawa met us at this well. It is 
their pradice to ftation a fmall party there, when caravans are 
expected, who remunerate themfelves for the fatigue of a ten 
days journey by fupplying provifions, and what elfe may be 
wanted by travellers, at an exorbitant rate. Many of our 
companions at this time had great need of their affiftance, as 
their fupply had been originally infufEcient, and many camels 
had perifhed on the road. The vicinity of the Bir-el-Malha is 
occafionally infefted by the Cubba-Beefh, a wandering tribe, 
who, mounted on the fwifteft dromedaries, rapidly traverfe the 
defert, and live by plundering the defencelefs. As they are, 
however, unfurnifhed with fire-arms, fo numerous a body a& 
ours was not in much danger from their attack.. 
We remained at the Bir-el-Malha till the 12th; on which 
day we left that place, and travelled with little interruption till 
the 20th, and then encamped at a fpot called Medwa, where 
however is no fupply of water. One of my camels having 
fallen, 
