BONES. 135 



Sheep's Clot of Dried 



blood. ox blood. blood. 



Water 87-4% 30-56 % 12-50% 



Organic matter ... 11-4,, 51'43 



Ash 1-2,, 18-01) " 87 ' 5 " 



Nitrogen ... ... 1-5,, 5'9 ,, 10-52,, 



Phosphorus pentoxide 0-03 ,, I'O ,, 1*91 ,, 



Blood easily decomposes in the soil, and its nitrogen and 



phosphoric acid soon become available to the plant. It gives 



excellent results with wheat. 



Bones are an important manure and are used in many forms. 

 They form the hard framework of the body of an animal and 

 are largely composed of mineral matter mainly phosphate of 

 lime. In addition there are, in fresh or " green" bones, about 

 30% of organic matter, containing, perhaps, 3 to 4% nitrogen, 

 and a certain amount of fat. This last ingredient is objection- 

 able, since it hinders the decomposition of the organic matter 

 after the bones are applied to the soil, partly mechanically and 

 partly, perhaps, by forming a lime soap which gives an imper- 

 vious crust to each fragment. Moreover, it renders the grind- 

 ing or disintegration of the material more difficult. For this 

 reason, and also in order to extract gelatine from the bones, 

 they are often submitted to the action of steam under pres- 

 sure ; they are thus robbed of a large portion of their fat and 

 some of their nitrogenous matter, and are rendered much more 

 friable and more susceptible to processes of putrefaction and 

 decay. 



Bones when applied to the soil in large fragments only 

 slowly become assimilable, remaining almost unchanged in 

 some cases, especially on clay soils, for years. They are 

 therefore always now reduced to small fragments before being 

 applied, being graded according to their degree of fineness, as 

 "half-inch bones," "crushed bones," "bone dust," "bone 

 meal," and " bone flour." Sometimes bones are treated with 

 acid, when the calcium phosphate dissolves, and the organic 

 matter, from which glue is made, is left behind. From the 

 acid solution, by the action of lime, the calcium phosphate 

 can be precipitated and the dried product is sometimes sold as 

 " precipitated bone flour." 



