CHAPTER XII 



POTASSIC MANURES. MANUFACTURE FROM 

 CRUDE SALT. MANUFACTURE FROM FELD- 

 SPAR. MANUFACTURE FROM SUNFLOWER 

 AND KELP PLANTS 



THE ash of plants consists for the most part 

 of carbonate of potash, the caustic and deter- 

 gent properties of which attracted attention 

 from the very beginning of civilization. And 

 as a matter of fact the ancients knew this sub- 

 stance and employed it in domestic economy 

 as well as in industry. Aristotle described the 

 manner of extracting potash from the ash of 

 plants. His process is still in use in certain coun- 

 tries. It consists in submitting the ash to a series 

 of washings with water, concentrating the lye 

 by evaporation, and in calcining the residual 

 s?lt. As plants leave only a small amount of 

 ash, and as this does not wholly consist of car- 

 bonate of potash, it is clear that the yield of 

 potash cannot be very great. 



Carnallite forms the chief ingredient of crude 

 potash salts. There are five crude salts known 

 as Sylvinite kainit, schoenite, polyhahite, krugite 

 and carnallite. 



In the manufacture of potassium chloride 

 101 



