56 CHEMISTRY, GEOLOGY 



which require a small quantity of those sub- 

 stances. 



In every ten gallons of milk there is about 

 half a pound of bone-earth ; hence a cow which 

 gives twenty quarts a day takes from the soil 

 about two pounds of phosphate of lime every 

 week. To restore these two pounds of phos- 

 phoric acid and lime to the soil, three pounds of 

 bone-dust are required ; and, by the process of 

 decomposition, the land obtains the phosphoric 

 acid and lime of which the inorganic part of the 

 bones was made. 



For manure, bones are sometimes dissolved in 

 sulphuric acid; and, for this purpose, equal 

 weights of bone-dust and acid are mixed together, 

 and allowed to stand until the acid has chem- 

 ically decomposed the substance of the bones. 



By thus preparing the bones for manure, the 

 substances of which they are composed are very 

 minutely divided ; they are, on this account, 



Questions. How much bone-earth in every ten gallons 

 of milk? How much bone-earth is taken from the soil 

 every week by a cow giving twenty quarts of milk a day ? 

 How much bone-dust is required to make good to the soil 

 what it thus loses ? Are bones applied as manure in any 

 other form ? What is the advantage of thus preparing the 

 bones ? 



