56 AMERICAN MANURES. 



partially converted into soluble phosphate, etc., 

 which, on being neutralized in the soil by lime, 

 or by sesquioxide of iron, alumina, etc., is then 

 brought into a very fine state of division. As 

 the neutralization takes place in the soil itself, 

 the phosphate is incorporated with the same in 

 the simplest and most intimate manner. How- 

 ever fine the bones may be ground by mechan- 

 ical operations, their tissue is not destroyed in 

 them, and the phosphates within them are in a 

 relatively raw condition. As to coprolites, even 

 converted into powder ever so fine, they cannot 

 have any effect on the soil, unless it contains 

 free acids. Precipitated phosphates have not 

 only a larger volume than those merely pulver- 

 ized, but they are also, as w r e have proved, more 

 freely soluble in water than mineral phosphates. 

 Even if their elementary composition be the 

 same, the finely divided condition of the precipi- 

 tated phosphate presents indisputable advantages. 

 The precipitated phosphate is dissolved by the 

 most dilute acetic acid, while it has little action on 

 the finest bone-meal, and still less on coprolites. 

 " The secret, therefore, of the efficiency of 

 superphosphates consists in the fact, that the 

 oluble phosphates of the superphosphate are 

 converted in the soil itself into an insoluble but 

 very finely divided product. If this change took 

 place before the dissemination of the fertilizer, the 



