The Story-Book of the Fields 



gallons of milk), reduced to powder and 

 spread over the pasture, will compensate for 

 the weekly loss in phosphate drawn from the 

 ground by the cow's production of milk. 

 Such is the advantage derived from the use 

 of powdered bones on exhausted pastures. 



Phosphoric acid, in combination with other 

 substances, is found in all agricultural 

 produce, so that the phosphate contained 

 in bones has a remarkable effect on our 

 harvests. A harvest has been doubled, as 

 if by enchantment, by the use of powdered 

 bones. One pound of this powder will con- 

 tain the phosphoric acid needed for the 

 production of one hundred pounds of wheat. 

 In spite of their powerful effect, the use of 

 bones in agriculture must always be limited, 

 because there are not enough of them, and 

 because they are largely used for other 

 purposes. Fortunately, in some places phos- 

 phate of lime is found in the form of stones 

 called nodules or coprolites. These precious 

 stones are carefully collected and reduced to 

 powder in a mill, and so that the substance 

 shall be more soluble in the dampness of the 

 soil, and consequently more effective for the 

 nutrition of plants, it is sprinkled with a 

 highly corrosive liquid, called sulphuric acid, 



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