Dr. A. Holmes — Non-German Sources of Potash. 253 



by the railway from Iquique, has been found by chemical prospecting 

 to be potash-bearing over an area of 20 square miles. 1 The potash 

 is confined to a hard superficial crust averaging a foot in thickness, 

 which overlies a loose granular deposit of glauberite and gypsum. 

 The composition of the crustal salts is approximately 70 per cent 

 JSTaCl with 30 per cent of sulphates, among which glaserite, 

 (K, Na), S0 4 , is the chief. As in the Indian deposits, the effective 

 extraction of potash presents a difficult problem to chemical 

 engineering. Deposits that hitherto have not been worked, and 

 of which very little is known, are said to occur in Holland, Sicily, 

 Russia, Morocco, and Peru. 



Alsatian Deposits. — The Alsatian deposits were discovered near 

 Mulhouse in 1904 during a survey of the district for coal and oil by 

 borings. They have since been thoroughly investigated, and are 

 known to underlie an irregular oval-shaped area of about 80 square 

 miles, 2 bounded by the Jura on the south, the Vosges on the west, 

 and the Rhine on the east. A continuation of the same formations 

 has also been recognized across the llhine, but as yet the occurrence 

 of potash in Baden remains hypothetical. The general succession of 

 the Alsace deposits is stated in the accompanying table in comparison 

 with those of other areas. Potassium salts occur in two well- 

 marked beds separated by 50 to 80 feet of dolomitic marl. The 

 lower bed is both thicker and more extensive than the upper, and is 

 encountered at depths varying from 2,000 to 3,300 feet in different 

 parts of the field. The beds are continuous, and as they are only 

 very gently folded, unlike the Spanish deposits described below, they 

 can be worked without difficulty. Moreover, they are superior in 

 character to the German deposits because of the absence of carnallite. 

 Each bed consists of practically pure sylvinite, in bands alternately 

 red and grey, the average percentages of KC1 being 35 and 30 for 

 the upper and lower beds respectively. The field, as a whole, is 

 estimated to contain over 400 million tons of KC1, a reserve ample, 

 were it necessary, to supply the combined requirements of France, 

 Great Britain, and the United States for several centuries. 



The Alsace deposits differ most conspicuously from those of other 

 regions by the deficiency of sulphates, salts containing MgS0 4 being 

 absent, while even anhydrite and gypsum are less abundant than is 

 usual. On the other hand, the succession of deposits begins with 

 dolomite, and dolomitic beds occur at various horizons throughout, 

 indicating that calcium and magnesium were present in normal 

 quantities, and that they were precipitated as carbonates rather than 

 as sulphates. The absence of sulphate is not improbably due to the 

 bituminous character of the deposits, and conforming to the implied 

 suggestion of reduction the bituminous beds are found to be 

 unusually rich in sulphides. 



1 H. S. Gale, Eng. & Min. Journ., vol.cv, p. 674, 1918 ; R. C. Wells, ibid., 

 p. 678. 



2 For a map of the area and a general discussion of its commercial value and 

 political significance, see Paul Kestner, Journ. Soc. Chem. Ind., vol. xxxvii, 

 p. T 291, 1918. 



