POTASSIC MANURES 111 



liquor used to boil the residual salt, are alone 

 used as solvent; all addition of water is avoided. 

 After having brought the solvent solution in the 

 pan to the boil, the raw salt is run in as before 

 and the whole boiled without interruption until 

 the solution tests 35 to 36 Be. At that density 

 the carnallite in the crude salt easily dissolves 

 if the liquid be hot enough, i.e., if the steam be 

 of sufficient tension. Certain factories insert 

 an agitator whose action contributes to mix 

 the solution, consequently to obtain a better 

 result from the crude salt. Nevertheless, the res- 

 idue is sometimes rich in potassium chloride; 

 and is boiled a second time with pure mother 

 liquor. The solution so obtained is clarified in 

 the same way as in the first method; on cooling, 

 it deposits not potassium chloride but carnal- 

 lite, which is allowed to drain and then dissolve 

 in boiling water to extract the potassium chloride. 

 As common salt, as well as kieserite, dissolves only 

 slightly when hot in a concentrated solution 

 of magnesium chloride, while potassium chloride is 

 very soluble therein, it is clear that the solu- 

 tion prepared by this process should contain 

 very little common salt, and also that the car- 

 nallite which crystallizes therefrcm should contain 

 very little, and the chloride of potassium fur- 

 nished by the latter should be of high strength. 

 This method, however, has the drawback of 

 yielding a large amount of carnallite, the re- 

 moval and solution of which require much labor 



