344 Dr. A. Holmes — Non-German Sources of Potash. 



amount to over 1 10,000 million gallons, averaging about 4 per cent of 

 KC1, and, therefore, containing 24 million tons of that salt. 



Composition of American Potash Brines. 



During the evaporation processes, sodium carbonate and sulphate, 

 and borax are produced, and finally crude potassium chloride (75 to 

 80 per cent KC1) is recovered. At the present rate of working, from 

 50,000 to 60,000 tons of the crude salt are produced annually, 

 together with one quarter that amount of borax. 



Other American Brines. — In Nebraska an area of some 8,000 square 

 miles is occupied by sand-dunes, interspersed with fiat-bottomed lakes 

 or salt marshes. These represent every stage of evaporation, from 

 nearly freshwater to residual brines. The " lakes" are generally 

 underlain by green muds and beds of sand, the latter containing the 

 whole of the brine when superficial water no longer remains. The 

 potash-content varies from 9 to 35 per cent of the dry salts, and when 

 commercial operations on the richer brines were undertaken in 1915, 

 they met with such success that the following year's results gave 

 Nebraska first place in the United States as a producer of potash. 1 

 Jesse Lake 2 is the most important of the basins from which brine is 

 pumped, and a statement of its composition is listed above. The 

 sands of the dune area are rich in orthoclase and microcline, but in 

 a semi-arid climate it is unlikely that much potash can have been 

 derived directly from such a source. The richness of the brine in 

 carbonates suggests that its dissolved contents represent an accumula- 

 tion of wind-blown ashes from years of prairie fires, concentrated by 

 intermittent surface drainage. 



In Utah potash was recovered from the brine of Great Salt Lake 

 during 1916 and in later years, but, as the analysis shows, it is 

 unlikely that the production can continue to compete with that from 

 more favoured sources. In the Salduro Salt Marsh, 3 however, Utah 



1 Eng. & Min. Journ., vol. civ. p. 827, 1917. 



2 E. E. Thun, Met. & Chem. Eng., vol. xvii, p. 693, 1917- 



3 Eng. & Min. Journ., loc. cit. 



