campbkll.] BORAX DEPOSITS OF EASTERN CALIFORNIA. 405 
thickness of the crust could not be determined, but it can not be less 
than 1 foot of solid salt. A sample collected in the middle of the 
field on this road shows that the salt is composed of chloride of sodium, 
94.54 per cent; chloride of potassium, 0.31 per cent; sulphate of 
sodium, 3.53 per cent; sulphate of calcium (hydrous), 0.79 per cent; 
moisture, 0.14 per cent; undissolved residue (gypsum and clay), 0.50 
per cent; total, 99.81 per cent. The presence of the large amount of 
mechanical impurities as well as the large percentage of sulphate of 
soda would render refining necessary before the salt could be placed 
upon the market, a process that would be very expensive under 
present conditions of great scarcity of fuel and water and lack of 
railroad transportation. 
