THE GEEAT DESERT. 467 



at the eastern base of Pilot Peak, just beyond the western limit of Map 

 III, where the accumulations of crystals of common salt cover the surface 

 to a depth of several inches over an area of many square miles. Some of 

 the ordinary surface incrustation was taken from the desert to the west of 

 White Eock Pass in the Cedar Mountains, and subjected to chemical 

 analysis. It contained 97.43 per cent, of soluble matter, which gave by 

 analysis : 



Soda 39.06 39.28 



• Potassa trace trace 



Lime -., 0.10 0.09 



Chlorine 60.31 60.49 



Sulphuric acid 0.18 0.17 



99.65 100.03 

 or, combined theoretically: 



Chloride of sodium 99.37 99.68 



Sulphate of lime 0.24 0.22 



.Excess S O3, 0.04 Na 0,0.09 



99.65 99.99 



A chemical examination was also made of the ordinary desert soil. 

 The material analyzed was obtained from near the Dugway Station on the 

 old Overland Stage Road, about 25 miles south of the limits of the map. 

 That taken from the surface, an exceedingly fine, almost impalpable powder 

 of a light brownish-gray color, known in the West as "alkali dust", was 

 treated with warm water; only 0.5 per cent, of the mass was found to be 

 soluble. This gave, on analysis: 



Lime 31.22 30.87 



Magnesia 1.84 2.41 



Soda ,. 9.54 9.20 



Sulphuric acid 45.60 45.48 



Chlorine 9.78 10.81 



97.98 98.77 



