70S 



Boiled bones arc prepared by boiling the bones or by treating 

 them with steam under a high pressure, which extracts a lar^e pro- 

 portion of the fat and gelatine they contain. The bones are ren- 

 dered more porous and brittle. They contain from I. 1 , to 2 per 

 cent, of nitrogen and from 54 to 63 per cent, of phosphate of lime. 

 They arc of less value, as far as the nitrogen is concerned, than raw 

 bones, but they are more valuable in the phosphates, which are not 

 only higher bn; more soluble. Konig found that raw bones did 

 not disappear before four years from the soil, while boiled bones 

 disappeared in ten months. 



Dissolved bones are prepared by treating them with sulphuric 

 acid to convert part of the insoluble phosphate of lime into a 

 soluble state. This is the most valuable bone manure, and one of 

 the best soluble phosphatic manures. There is not so much of this 

 manure made now as formerly, the cheaper superphosphates made 

 from mineral phosphates, phospho-guanos, bone ash, and bone 

 charcoal taking its place. 



BONE ASH. 



By burning bones the organic matter and moisture is burned 

 out of them, leaving a white ash which contains from 64 to 86 per 

 cent, of phosphate of lime, but no nitrogen. It is principally used 

 for the manufacturing of superphosphates. It is sometimes used to 

 adulterate bone manures, or when dissolved, sold as dissolved 

 bones, which it has no right to be called, as it is no more bones 

 than mineral phosphates are. It is certainly inferior to bones in its 

 action in the soil. 



Bone black or bone charcoal is made by burning bones in 

 closed retorts or kilns. The nitrogen distills over as ammonia, 

 and is collected in sulphuric acid. The black charred mass is 

 taken out of the retorts and cooled. Bone black is principally 

 used in sugar refining. After some time it loses its power of 

 clarifying the sugar solution from coloring matter, and it is then 

 used to make superphosphates. It is slightly superior to bone ash r 

 but very much inferior to bones as a manure. 



The use of these two phosphates in the soil will be best dealt with 

 when we come to superphosphates, as they are generally made into 

 these. 



COPROLITES, OR MINERAL PHOSPHATES. 



Coprolites have been found in a great many parts of the world. 

 Those found in the sedimentary rocks are generally in an amorphous 

 or non-crystalline state, and called coprolites. Those found in the 

 older rocks are crystalline, are called apatite, and the non-crystalline, 

 phosphorite. Those that are sent into the market contain from 60 

 to 88 per cent, of tricalcic phosphate. As a manure they are of very 

 little value in the raw state, although there are some people who 

 hold a different opinion. For them to be of any value in the raw 

 state they must be ground to a very fine powder and used on soils 

 deficient in lime. They must be used in large quantities to do any 



