BYE-PRODUCTS OF GELATINE AND GLUE 273 



valuable bye-product, but there is also another of equal 

 importance, viz. the phosphate of lime, which comprises 

 about half the raw material. As previously described in 

 Part IV., Section II., p. 225, this is usually extracted after 

 the grease, by solution in weak hydrochloric acid. The 

 solution is neutralized in lead-lined vats with milk of lime, 

 a precipitate of di- and tri-calcium phosphates being obtained. 

 Calcium chloride is left in solution, and the precipitate should 

 be, therefore, well washed if it be desired to have dry 

 phosphate. The bone-glue industry is, generally speaking, 

 much more intimately connected with the fertilizer trades 

 than the skin-glue trades, indeed the extraction of the bones 

 for glue is not always advisable, in which case the protein 

 matter as well as the phosphatic matter of the bones are 

 employed for making " bone manures." For details of this 

 industry the reader is referred to a companion volume in 

 this series on " Chemical Fertilizers." 



REFERENCES. 



" Chemical Fertilizers and Parasiticides," S. H. Collins, M.Sc. 



" Bones," Part II., Section V., p. 72. 



" Precipitated Bone Phosphate," Part III., Section III., p. 157. 



" Bone Manures," Part III., Section V., p. 173. 



" Gelatine, Glue, and Allied Products," T. Lambert. 



E. 18 



