306 EGYPTIAN AGRICULTURE. 



KAINIT. 



This is the most widely used potash manure, and is 

 simply the natural layer crushed. It consists of sulphates 

 and chlorides of potassium and magnesium and always 

 contains considerable quantities of rock salt (30-40%). 

 Its composition varies somewhat but as a rule the 

 potash K 2 averages 12 J, equal to some 23^ 

 sulphate, in which form it is largely present. 



CALCINKD DOUBLE SULPHATE. 



By a rather complicated process there can be prepared 

 from kainit a double sulphate of potassium and magnesium 

 with water of crystallisation. On heating this salt a 

 portion of the water goes off and the remaining mass 

 contains on the average 26 % potash, equal to 48 % 

 sulphate. This is an important potash manure which 

 may be regarded as a kind of concentrated kainit. 



MURIATE (OR CHLORIDE) OF POTASH. 



This salt is prepared from the natural layer carnallit 

 and contains fully 50 % potash, equal to some 80 % 

 chloride. It is employed as a manure to a considerable 

 extent, as in cases where questions of transport arise, its 

 high potash content gives it an advantage over the two 

 manures just referred to. 



Generally speaking however, it is better to apply potash 

 to land in the form of sulphate rather than as chloride, as 

 many crops do not appear to do well in the presence of 

 the latter salt. For one thing the chloride, though a more 



