( 58 ) 

 heaped up it is moist, and in presence of wa- 

 ter the sulphuret which it contains is trans- 

 formed into sulphate. The heat, developed 

 during the oxidation of the iron, gradually in- 

 creasing, hastens the reaction, and finally in- 

 flames the peat, which continues to burn slowly. 

 By this spontaneous combustion, we obtain a 

 gray ash winch serves as an amendment for 

 meadows. The sulphate of lime which it 

 contains, is not the sole cause of its beneficial 

 action upon vegetation, as its influence in this 

 respect, is mainly due to its nitrogenous con- 

 stituents; for analysis show^s that it has half 

 per ct. of nitrogen. Boussingault thinks that 

 sulphate of ammonia is produced during the 

 incineration of pyritous peats. Picardy ashes 

 are sold upon the spot for about three cents 

 per bushel, and they are applied to meadows 

 in the proportion of 4i to 6 bushels per acre. 

 Vitriolic Jlshes. These so called residues, 

 from the manufactories of copperas, are anala- 

 gous to the preceding. Sometimes the leeched 

 pyritous earths are mixed with one-fourth 

 their weight of peat ashes, in which mixture 

 they are applicable to meadows and to sandy 

 soils. These ashes, more nitrogenous than 

 the Picardy, contain 2.72 per ct. of nitrogen. 



