98 Fertilizers 



given (page 94), in spite of its slightly greater cost. It is 

 rather less diffusible than the muriate, though it is not 

 inferior to it as a source of actual potash. 



Double manure salt. 



Double manure salt, or double sulfate of potash and 

 magnesia, is a product obtained by refining kainit by 

 recrystallization. Though it contains less potash, it is 

 similar in its effects to the high-grade sulfate of potash, 

 because it contains no chlorids, and is free from other dele- 

 terious substances. In many cases the 25 per cent of 

 sulfate of magnesium with which it is associated is believed 

 to be of considerable service. The potash contained in it 

 is equivalent to 25 to 26 per cent actual potash. The cost 

 of potash in this material is greater than in the muriate. 



Potash manure salt. 



Potash manure salt is a term used to designate a low- 

 grade muriate of potash containing 20 per cent of actual 

 potash. It may be employed in a manner similar to the 

 use of muriate of potash. It must be remembered, how- 

 ever, that the potash contained is in the form of a chlorid, 

 and that other impurities including sulfate and chlorid 

 of magnesium, common salt and a few other compounds 

 are associated with it. 



Double carbonate of potash and magnesia. 



This material imported from Germany is a finely divided 

 powder containing about 20 per cent of potash and an 

 equal amount of magnesia free from chlorids. On ac- 

 count of the small amount brought to this country it is 

 relatively unimportant. 



