Phosphates 



directly in agriculture, because ol their spongy 

 texture which the rootlets can penetrate, and so 

 give appreciable results. Their value is variable, 

 according to the way in which they are used and 

 their richness in fertilising elements. Their action 

 is not so slow as that of many tricalcic phosphates, 

 but generally they are turned into superphosphates, 

 being monocalcic phosphates of high value and 

 eminently assimilable. 



They should never be bought except under 

 analysis. 



Deglutinised or Steamed Bones. — The name of 

 this manure comes from the process of deglu- 

 tinising bones by submitting them to the steam of 

 super-heated water. In this process, as in the 

 manufacture of animal charcoal, the bones have 

 been previously degreased. The gelatine which is 

 obtained from them constitutes nearly half of the 

 nitrogenous organic matter, often even more ; 

 so that steamed bones are much poorer in nitrogen 

 than green or fermented bones. On the other hand, 

 they contain more phosphates, the proportions 

 being about 0*9 to 1-5 nitrogen, and from 60 to 70 

 tricalcic phosphates. 



Steamed bone is very easily and completely 

 pulverised, the resulting powder being known as 

 Stemned Bone Flour, which is the finest bone 

 manure, although the phosphate is in a tricalcic 

 form. On account of its fineness, however, this 

 manure is generally comparatively assimilable, and 

 although the value of the imit is sensibly less than 

 in superphosphate, it may be used with advemtage, 

 especially in light acid soils. 



58 



