PULVERIZED LIMESTONE 



239 



Fig. 153.— Soil acidity caused by mineral acid. Sulfide sludge washed over bottom-land. 

 Weathering of sludge destroyed the grass. (Wisconsin.) 





Fig. 154. — A limestone quarry. A source of agricultural lime. . 



coarse particles give to the soil a reserve of lime carbonate. The 

 best grades of limestone contain from 90 to 100 per cent carbonates. 



