Muriate of Potash 31 



tables. There are several reasons for this. 

 First, there are impurities present which if 

 they contain an ion in common with the 

 principal salt may necessitate the use of more 

 water. To illustrate this suppose there are 

 10 grams of sodium chlorid in every 50 grams 

 of the crude potassium chlorid (a chlorid ion 

 in common), then it is necessary to furnish 

 water for the sodium chlorid as well as for 

 the potassium chlorid; while if 10 grams of 

 calcium nitrate were present (no common ion : 

 K+, Ca+, NO.s", C1-) this substance would 

 dissolv in the solution already saturated with 

 potassium chlorid. Second, sufficient water 

 should be present so that the solutions may 

 be filterd before they approach saturation; 

 otherwise the crystallization that results on 

 cooling clogs the filter and causes delay. 



In filtering all such mixtures which con- 

 tain fine sediment, first allow them to settle 

 and bring the solid matter onto the filter 

 only at the end of the operation after the 

 clear liquid has past thru the filter. 



Kieserit, the magnesium sulfate with one 

 molecule of water, is the salt that has sepa- 

 rated out in the German deposits. Ordinarily 

 from water the heptahydrate, MgS04 • 7H2O, 

 separates out. Epsom salts, the hepta- 

 hydrate, are made from kieserit by dissolving 

 kieserit and allowing the salt to crystallize. 



