CHAPTER XIV 

 SOURCES AND USE OF POTASH SALTS 



99. Occurrence. Potassium is one of the ten elements 

 absolutely essential to plant growth. Some crops are es- 

 pecially heavy feeders on this element, prominent among 

 them being the legumes, the root crops, the sugar-pro- 

 ducing crops, and tobacco. Any crop is particularly sen- 

 sitive to a deficiency of potash. 



The main commercial sources of potash salts are the 

 Stassfurt deposits. These deposits are located in Saxony, 

 Germany, and extend eastward from the Harz Mountains 

 to the Elbe River about 60 miles, and from the city of 

 Magdeburg southward to the town of Bernburg about 

 20 miles. The deposits of these salts in this region are amply 

 sufficient to supply the world for many centuries. 



These deposits are the result of the evaporation of 

 an ancient inland sea which became isolated from the 

 ocean. During the time of this evaporation, the climate 

 of the section in question is supposed to have been trop- 

 ical. As the evaporation continued, various salts crys- 

 tallized out in the order of their insolubility. The lowest 

 stratum consists of sulphate of lime, CaSCU; the next 

 stratum consists of rock salt, which in places reaches a 

 thickness of 3000 feet; the third stratum is the mineral, 

 which consists of sulphate of lime, potash, and magnesia. 

 Above this stratum comes the kieserit region, where there 

 is a layer of sulphate of magnesia, and upon it rests a 

 deposit of carnallite, which is a mixture of potassium chloride 

 and magnesium chloride. The carnallite deposit varies in 

 thickness from 50 to 130 feet. This deposit yields most 

 of the crude potash from which the more concentrated 



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