Manures in General 



from other causes. Thus tricalcic phosphate is 

 usually slightly assimilable ; it is very little so in 

 the ordinary mineral phosphates, but more so in the 

 Tunisian phosphates, and in steamed bone flour. 



The most soluble being the most assimilable, 

 they are generally taken as type manures and the 

 value of units of other manures of the same nature 

 established in comparison with them. 



Fineness. 



The fineness to which manures are reduced has 

 a much greater importance than is generally attached 

 to it. Some substances are not really manures only 

 because they are presented in too large particles. 

 A striking example is that supplied by Mr. Hendrick 

 in morsels of bone coming from bone meal which, 

 when dug up after lying in the earth for twenty 

 years, were found to be still nearly as rich as the 

 richest bone meals of commerce. Here is their 

 analysis : 



100-00 



This shows that in twenty years these bones had 

 given nothing to the plants. 



' Containing N 3*53, equal to ammonia 4*29. 



22 



