VI.] THE STASSFURT DEPOSITS i6i 



gathered together the magnesium and potassium salts, 

 which would be the last to remain in solution. The 

 manufacturing is extremely simple in principle ; the 

 salts of the potash region, chiefly carnallitc, are mixed 

 and brought into solution, from which products of 

 various grades of purity can be obtained by evaporation. 

 In this way are obtained the sulphates and muriates of 

 potash of commerce, but the substances chiefly used in 

 agriculture are certain crude salts contained by grinding 

 suitable mixtures of the original material as mined. Of 

 these the best known in this country is kainit, a mineral 

 which, properly speaking, only occurs in some of the 

 mines where water had formerly access, but which 

 commercially represents a mixture of sulphates and 

 chlorides — chiefly sulphates, of sodium, potassium, and 

 magnesium, containing a little over 12 per cent, of 

 potash. 



A crude "hard salt" or "sylvinit," consisting chiefly 

 of chlorides, but equally containing 12 per cent, of 

 potash, is put upon the market rather more cheaply 

 than the kainit, and for most purposes will serve equally 

 well. Owing to the rapid exhaustion of the true kainit 

 deposits, this material is now taking the place of 

 kainit in the manure market. In Germany a crude 

 "carnallite" of still lower grade, containing only about 

 9 per cent, of potash, is used, but its hygroscopic nature 

 and low concentration prevent its export to any distance. 

 Table XLII. shows the analyses of the chief Stassfurt 

 products, of which only i, 3, 4, and 6 come to this 

 country in any quantity. 



The Stassfurt salts are white or grey or pink (owing 

 to the presence of a little iron as impurity) gritty 

 powders, which dissolve readily and almost entirely, and 

 are, as a rule, more or less deliquescent. Potassium 

 chloride, and particularly magnesium chloride, are very 



