Commercial Fertilizers. 159 



The commercial materials on the market are muriate of potash, 

 sulphate of potash, sulphate of potash and magnesia, kainit, to- 

 bacco stems and wood ashes. 



Muriate of potash is manufactured by concentration from the 

 crude minerals obtained from the Stassfurth mines of Germany. 

 These mines of Stassfurth are immense saline deposits, formed 

 by evaporation of large inland seas, cut off from the ocean by 

 geological changes. These deposits are the main source of all 

 commercial potash fertilizers. The muriate contains about 50 

 per cent of potash, all of which is combined with chlorine. At 

 the present price per ton it supplies potash at a cheaper price 

 per pound than any of the other materials. It can be used on 

 all soils and all crops except a few, such as tobacco, potatoes and 

 sugar beets, which appear to be injured in quality by the chlorine 

 present. 



Sulphate of potash. This is another concentrated product of 

 the Stassfurth industry. "What is known as "high grade sul- 

 phate" contains about 50 per cent of potash in the form of 

 sulphate. A low grade is also made, which contains from 30 

 to 35 per cent of potash. The sulphate of potash is of special 

 value for those crops injured by chlorides, as mentioned above. 



Sulphate of potash and magnesia. This is sometimes called 

 ^'double manure salt," It is obtained from the Stassfurth 

 mines, and contains 25 to 28 per cent of potash. It is a mixture 

 of magnesium sulphate and potassium sulphate. Unless the cost 

 per pound of actual potash in this material is less than in other 

 forms, it has no special quality to recommend it. 



Kainit. This is the most common product of the Stassfurth 

 mines and is a mixture of various salts. It contains from 12 to 

 14 per cent of potash, chiefly in the form of sulphate. It also 

 contains a considerable quantity of common salt, some chloride 

 and sulphate of magnesium, a small quantity of gypsum and a 

 small amount of potassium chloride. It is a low grade potash 

 salt and while it is cheaper per ton, the actual potash costs more 

 in kainit than in the muriate or high grade sulphate. For this 



