MANUFACTUEE OF BONE SUPEEPHOSPHATE. 1ST 



ciently differentiates it from the above-named bone dusts. Thus 

 established, the differentiation of the different quaUties of bone dusts 

 is very sharp, and they are no longer confused with mixture of horn, 



hair, etc. 



Adulteration.— Bone dust is the subject of numerous sophistica- 

 tions. Finely crushed gypsum and corozo powder are often found 

 therein, substances which it is impossible to recognize by the naked 

 eye. In that case the analysis of the product shows that its per- 

 centage of nitrogen and phosphoric acid is inferior to the normal, 

 for corozo only contains 2*44 per cent phosphoric acid and^ 0-96 

 per cent nitrogen, and gypsum contains neither of these ingredients. 

 But the most frequent adulteration consists in adding to it phos- 

 phorite, or the phosphatic lime of the glue manufacturers, or a mix- 

 ture of phosphate of lime and greaves. As all these products are rich 

 in phosphoric acid, their effect is to increase the total phosphoric 

 acid of the product, and to diminish considerably its percentage of 

 nitrogen. To hide as much as possible the difierence between the 

 two elements which w^ould be revealed by analysis, sophisticators- 

 resort to sulphate of ammonia. But, as already pointed out, the 

 essential element besides phosphoric acid is ossein, or gelatine, 

 which cannot be replaced by nitrogenous debris of animal origin, 

 and far less by sulphate of ammonia. The above sophistications. 

 are therefore very prejudicial to the farmer, even if he receives in 

 that w^ay more nitrogen and phosphoric acid than furnished to him 

 by normal bone dust. The mixture of phosphorite or of phosphate 

 of lime and ammoniacal salt can never replace bone dust. Na 

 more can the mixture of phosphate of lime and greaves replace it, 

 for the nitrogenous elements of this mixture do not consist of ossein, 

 but rather of a substance analogous to horn. 



As regards the impurities, sand, etc., and the degree of moisture,, 

 they should not exceed certain limits. Like all pulverulent sub- 

 stances, bone dust draws moisture from the air and the manufacturer 

 cannot be responsible for it. The normal moisture is 4-7 and the 

 percentage of sand 2*4 per cent. 



Manufacturing of Bone SujJeiyhosjjhates.—As just seen, bone 

 dust differs in composition with the nature and quality of the bones, 

 from W'hich it is derived and the method of manufacture. In 

 normal bone dust, the ratio of the nitrogen to the phosphoric acid is- 

 as 1 : 5. Generally, however, there is found 0-5 to 1-0 per cent of 

 nitrogen from different debris of animal origin. Bone dust of this 

 nature may be delivered to farmers w^ithout other treatment. But if 

 the ratio between the nitrogen and the phosphoric acid is less, say 1 

 to 6, or beyond (Holdefleiss found a sample w^as 1 : 23-55), it is a 

 proof that the bones were too much degelatinized, and the dust is- 

 of less value if used diiectly as manure. It would behave in the 

 soil like a mixture of normal bone dust and phosphorite pow^der. 



