58 AMERICAN MANURES. 



under certain conditions, produces the liydrated 

 sulphuric acid, or oil of vitriol. 



Sulphuric Acid, or the Oil of Vitriol of com- 

 merce, technically termed 66 acid, contains 

 anhydrous sulphuric acid, 75 parts, and 25 parts 

 of water, in 100. This acid is extensively used 

 in the arts and manufactures, and in the pre- 

 paration of superphosphate of lime. It enters 

 into the composition of all cultivated plants, and 

 is usually found in small quantities in all soils, 

 forming gypsum or land plaster. It is also 

 found in some mineral waters. If needed by 

 soils, the cheapest source at the command of the 

 farmer is in gypsum or land plaster; every 100 

 Ibs. of which, when pure, contain 46.51 Ibs. of 

 sulphuric acid. 



ELEMENTS COMBINING WITH OXYGEN 

 TO FORM BASES. 



Calcium is a solid of a light golden yellow 

 color. It is harder than lead, and very malleable. 

 It oxidizes slowly in air at the ordinary tempera- 

 ture; but when heated to redness it fuses and 

 burns with a very brilliant white light, and is 

 converted into lime, this lime being an oxide of 

 calcium. This oxide occupies nearly the same 

 position among bases as sulphuric acid does 

 among acids, and is used in almost all the arts 

 and manufactures. 



