330 AGRICULTURAL TEXT-BOOK. 



Whennpplied. 

 to the fallow 

 do., or lea 

 do 

 do 

 before grasses tt tares. 



Or at the average of 8 or 10 bushels a year per acre. 



Lime is found, in some of its shapes, over a large poition of the Uni 

 ted States ; but so far, its application as burnt lime has been much neg 

 lected. For further information we refer the reader to Prof. Johnston s 

 Essay on the use of lime in agriculture, 12 mo, pp. 259, Edinburgh, 1849. 



704. GYPSUM or PLASTER is a Sulphate of lime. lOOlbsof 

 common gypsum consist of 46 Ibs of sulphuric acid, 33 Ibs of 

 lime, and 21 Ibs of water. When it is heated to redness this 

 water is driven off, and the gypsum is very easily reduced to an 

 exceedingly fine powder. In this form it is used by masons. 

 It dissolves in 500 times its weight of pure water, or 50 gallons 

 will dissolve one pound. Thus it is often found in spring wa 

 ter, and in streams which pass through a soil in which gypsum 

 exists. In solution with water it is decomposed when mixed 

 with fermenting animal or vegetable matter. 



Gypsum acts very differently on different soils and in different 

 localities ; at times producing no visible effect whatever ; and at 

 others, becoming almost a necessary of profitable cultivation. 



The theory of its beneficial action has long been a subject of 

 dispute. The most probable solution is, that to a small extent 

 it supplies lime and sulphuric acid to the plant, but is chiefly 

 useful by the power it possesses of solidifying and retaining 

 the ammonical gases of air and earth. 



Benjamin Franklin first introduced it from France into the 

 United States. It was afterwards imported from Nova Scotia ; 

 and as New York, and the other Western States were settled, it 

 was discovered in abundance. Ohio and Michigan possess large 

 beds of it in various localities. It is quarried, and ground in 



