492 AGRICULTURAL ANALYSIS 



the deposit containing about 60 per cent, pure muriate of potash. 

 The liquors drawn from the crystallizing vats are boiled down 

 (now almost exclusively in a vacuum apparatus, but formerly in 

 open pans), during which process some chlorid of sodium and 

 sulfate of magnesium are separated. This second solution is 

 settled and run into crystallizing vats where practically all the 

 potash separates as crystals of pure artificial mineral carnallit 

 (KC1, MgCl 2 , 6H 2 O), which is treated precisely as was the crude 

 carnallit and gives a nearly pure muriate of potassium in one 

 crystallization. 



The crystallized muriate of potash thus produced is contam- 

 inated by chlorids of sodium and magnesium, through adhering 

 solutions, and these impurities are removed by a series of wash- 

 ings with water. The liquor from these washings of the crystals 

 is saved and used on fresh batches of the mineral ore. The crys- 

 tals of muriate of potash are dried and are from 70 to 99 per 

 cent, pure (KC1). The last "mother liquors," or solutions from 

 the crystallizing vats (from which all the potash has been sep- 

 arated), are used for the manufacture of bromin and chlorid of 

 magnesium. 



The muriate of potash (chlorid of potassium) manufactured 

 at Stassfurt is of various grades and contains actual potash in 

 the following proportions : 



Pure Muriate of Potash. Actual Potash. 



70 to 75 per cent, contains 46.7 per cent. 



So to 85 per cent, contains 52.7 per cent. 



90 to 95 per cent, contains 57.9 per cent. 



98 per cent, contains 62.0 per cent. 



When sold for fertilizing purposes it is on the basis of 80 

 per cent, pure muriate of potash, corresponding to 50.5 per cent, 

 actual potash. The price is based on this average and is in- 

 creased or decreased according to the percentage above or below 

 it of pure muriate contained, as shown by chemical analysis. 

 Muriate of potash serves as a basis for the manufacture of many 

 other potash salts, such as nitrates, chlorates, etc. 



There are many by-products in the manufacture of muriate 

 of potash, notably magnesium chlorid and sulfate of soda, which 

 latter, owing to its purity and freedom from acid salts, is largely 



