47 



is mined, refined, and exported to foreign markets. It is indis- 

 pensable in the manufacture of sulphuric acid, and is also used 

 in the manufacture of gunpowder, by bemg previously turned 

 into nitrate of potash, by a treatment with German muriate of 

 potash. It absorbs moisture, and so cannot be used alone for 

 gunpowder. Its chief effect appears to be upon grass crops, 

 but the difficulty attending its use is that it more readily 

 leaches out of soils than ammoniacal salts, so that where it has 

 been applied to a field, it is almost always to be detected in 

 ditches, draining the same. 



Nitrate of Potash. This material is a valuable source of both 

 nitrogen and potash. It is chiefly imported from India, and, 

 on account of its price, only used tor gunpowder or medicine. 



Ammoniaeal Plants. Another source of ammonia, and by far 

 the least expensive to the farmer to supply his laud with, will 

 be found in several plants, to be turned under as green crop. 

 Amongst these, we find in our section of country red clover and 

 peas, which appear to absorb nitrogen from the atmosphere, 

 and, by some process, to store it in the soil. It is also asserted 

 by an eminent chemist that some species of grass, weeds, and 

 especially the vetch, accomplish the same result. 



Potash. The supply of potash in the commercial fertilizers is 

 almost entirely derived from the German Stassfurt salts. Here 

 it is found in beds consisting of alternate layers of common salt 

 and the salts of lime, magnesia and potash. It was evidently 

 produced by the drying up of an inland sea. It has to be mined 

 and refined, when different grades are exported to foreign 

 markets. The best grade exported is the muriate, containing 

 from forty-five to fifty percent, pure potash. Of late years the 

 unmanufactured salt has been largely exported and highly 

 praised, but, in our opinion, a large amount of chloride of mag- 

 nesium present would render it injurious to most crops. Many 

 of these lower grades are sold under the name of Kainit. 



The soils which are first exhausted of potash are, first, sandy ; 

 second, light clay j third, marly ; fourth, heavy clay and allu- 

 vial. 



Sulphate Lime, Gypsum, or Land Plaster. This is extensively 

 applied to soils as a manure, and is also found largely in all 

 high grade superphosphates, or dissolved bone, as resulting from 

 the process of their manufacture. It really seems to be a spe- 

 cific for a clover crop, and its general action appears to be its 

 power of fixing the ammonia contained in the soil and atmos- 

 phere, in the presence of carbonate of ammonia a double de- 

 composition ensues, resulting in the formation of 

 ammonia and carbonate of lime. This substan< 

 burned, makes plaster of Paris. 



