204 



BONES. 



at present 9s. per cwt., whilst formerly the highest 

 quotation was 6s. 9d. Should it still increase, the 

 value given at page 168 for phosphate of lime must 

 be raised, since no other cheap source for procuring 

 this body is at present open to the German agricul- 

 turist. 



Bone-dust, when mixed with lime, sand, pit-coal 

 ashes, etc., contains of course a less proportion of 

 manuring constituents, and falls in value at a rate 

 proportioned to the increased quantity of these inop- 

 erative substances. Some specimens I have - ex- 

 amined consisted of from one fourth to one half, 

 nay, in one case, of three fourths, pit-coal ashes, 

 earth, and sand. 



As has been already mentioned, the action of bone^ 

 dust as a manure depends chiefly upon the gelatine 

 (nitrogen) and bone-earth (phosphate of lime) which 

 it contains. In respect of its more important or prin- 

 cipal constituents, it approximates somewhat closely 

 to the solid excrements of animals and straw, but is, 

 however, far richer in them, as the following table 

 will show. 



Bone-dust contains, therefore, about 12 times 

 more forcing elements, and from 80 to 100 times 



