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CHAPTER X. 



MANURES (CONCLUDED), SALINE AND MINERAL. 



Gypsum or plaster, its composition and properties ; reasons for ita 

 different effects. Common salt, its applications as a manure. 

 Nitrate of soda, native. Sulphates, their use and beneficial 

 action. Efficacy of these saline manures upon various crops ; 

 directions for their use 5 precautions necessary in their applica-* 

 tion. Wood ashes, their general composition and value-, spent 

 or lixiviated ashes . Anthracite coal ashes •, reasons why they 

 are worth preserving. Pearl ashes. Soot, its effects, and the 

 way in which it should be used. 



SECTION I. OF GYPSUM. 



Another important manure in which lime forms a 

 part, is plaster of paris, also called gypsum, and che- 

 mically, sulphate of lime. In this country it has been 

 more generally used perhaps than in any other, and 

 often with very great benefit. In many cases, a few 

 bushels per acre bring up land from poverty, to a very 

 good bearing condition : complaints are, however, 

 made, that after a time it injures the land in place of 

 benefitting it. This, in almost all instances, results from 

 using it alone, without applying other manures at the 

 same time. The explanation is of the same general 

 nature as that given under lime in Chapter ix. The 

 farmer has taken away a variety of substances, and 

 has only added gypsum. If the land is entirely ex- 

 hausted at last under such treatment, it is obviously 

 not the fault of the gypsum. There are many large 

 districts where it produces no effect; but it may al- 

 ways be considered certain, that where gypsum or lime 

 do no ftood, there is already, in one form or another, a 

 supply of both naturally in the soil; or, as has been 



