220 THE CULTURE OF FARM CROPS. 



chanical condition in which it is offered for sale, render it 

 of considerable interest to farmers. 



POTASH SALTS, form one of the most important sources 

 from which potash manures are derived. They are pro- 

 cured from the German salt mines and are largely imported 

 into this country and sold at a low price, compared with 

 their actual fertilizing value. They consist of varying pro- 

 portions of potash in combination as sulphate, and chloride, 

 with similar compounds of soda and magnesia. They are 

 known in the trade as muriate (chloride) of potash, sulphate 

 of potash, and kainite. 



MURIATE OF POTASH is the most valuable of these salts 

 as regards its contents of potash; but the excess of chlorine 

 contained in it is believed to be injurious to some crops; 

 while it is preferable for others which require this element 

 in considerable quantity. It contains on the average 50 

 per cent, of potash with some soda and magnesia, and at the 

 common price of about $40 per ton, the potash in it costs 

 about 4 cents a pound which makes it the cheapest source 

 of this material. 



SULPHATE OF POTASH, is a more popular form of these 

 salts, and contains about 35 per cent, of potash. The sul- 

 phuric acid contained in it is also valuable, and any excess 

 of it in the salts is quickly combined with other alkaline 

 matter in the soil and rendered useful, which is not the case 

 with the chlorine of the muriate. Hence the sulphate bears 

 a higher proportionate price in the market, and the potash 

 in it costs nearly 7 cents per pound. A lower grade of sul- 

 phate of potash contains 25 per cent, of potash, with consid- 

 erable sulphate of magnesia; the potash in this form costs 

 nearly 7 cents a pound. 



KAINITE, is the name given to the inferior grades of these 

 salts. A sample of a lot used by the author with excellent 

 results on grass, fodder corn, and turnips, had the following 

 composition, viz: 



Water... 2.15 percent. 



Lime 2 



Magnesia 11.30 " 



Potash 16.48 " 



Sulphuric acid 21.91 



