53 TRAVELS IN 
pebbles, embedded in this argillaceous matrix, were almost 
invariably tinged with a bright grass-green color. The sub- 
stratum of the mountains still continued to be a blue and 
purple-colored schistus. 
Having completed our stock of provisions, and procured 
from the inhabitants of Zwarteberg the loan of sixty stout 
bullocks, we once more launched upon the wide desert, and 
proceeded, on the twenty-third, near thirty miles to a spring 
of water called the Sleuf el fouteipi, and the following day en- 
camped on the banks of the Traka or Maiden river. The little 
water it contained was both muddy and salt, and the sand on 
its banks was covered with a thin pellicle of nitre, out of which 
was growing abundance of the salsola before mentioned. 
At sun-rise this morning the thermometer was down to five 
degrees below the freezing point. This great diminution of 
temperature appeared the more extraordinary, as no change, 
either in the direction or the strength of the wind, had taken 
place. The air was clear and serene, without a cloud in the 
sky, and the weather apparently the same it had been for se- 
veral days in every respect, except in the degree of tempeia- 
ture. The snow on the mountains could have had little in- 
fluence. The Black Mountains only were near, and they 
were to leeward ; the light wind that blew being from the 
west, in which quarter scarcely a hillock occurred for the 
space of an hundred miles. 
On the twenty-fifth we skirted the banks of the Traka about 
ten miles, passed the Ohonka or Boor's river, which was per- 
