86 THE SOIL OF THE FARM. 



These, mixed with the bones, in the proportion of three 

 to one, and moistened with the dniinings from the cattle- 

 yards, will furnish a highly fertilizing manure. The heap 

 requires to be made up in a covered shed, and having 

 been sutficiently moistened, is left to ferment. The mix- 

 ture is applied to grass land at the rate of thirty or forty 

 bushels per acre ; and to arable land at the rate of twenty 

 or twenty-five bushels per acre. 



As a general rule, bone manures are better adapted for 

 the liijhter class of soils than for stiff land. On some soils 

 their use has been attended with surprising effect ; but on 

 others, such as clay soils, for example, as may be already 

 naturally rich in phosphates, the application of bones is 

 of comparatively little benefit. 



(2.) Bone-ash is the residue left afterburning bones. 

 It consists of the earthy matter of the bone, and amounts 

 to about sixty-six per-cent. of the original weight. It is 

 chiefly obtained from South America, where large herds 

 of cattle are slaughtered, and the tallow melted from the 

 carcass, in which operation the bones of the animal are 

 used as fuel, thus forming the bone-ash of commerce. 

 The essential differences between crushed bones, dissolved 

 bones, and bone-ash, arc that while the first contains phos- 

 phate of lime and nitrogen, the second contains in addition 

 soluble phosphate, and the third has been deprived of its 

 nitrogen by burning. The bone-ash is chiefly used in the 

 manufacture of superphosphate of lime, which only differs 

 from dissolved bones in that it contains no gelatine or 

 animal matter yielding nitrogen. 



(3. ) Superphosphate. — By dissolving bones in sulphuric 

 acid they are rendered more available for the first crop, 

 and a smaller application sufiices at any one time. 



The bones arc first ground to powder, and then treated 

 witli sul])huric acid of specific gravity 1.00. A sufiicient 

 quantity of sulphuric acid is added to every ton of bone- 



