242 SOILS AMD MANUKES 



fine powders called bone meal, bone dust, bone flour, 

 etc., of which at least 90 per cent, should pass through a 

 sieve having eight wires to the inch. Less finely ground 

 specimens are called quarter-inch bones and half-inch 

 bones when 90 per cent, will pass through sieves having 

 respectively four wires and two wires to the inch. The 

 more finely ground qualities are, of course, the more 

 expensive, but they are distinctly the more remunerative. 

 Crushed bones have been used chiefly for pastures and 

 roots, but, on suitable land, are considered very good for 

 hops and garden crops, especially fruit. They are applied 

 at the rate of from 3 to 6 cwts. per acre, generally at the 

 back end of the year. 



Steamed Bones. The term " steamed bones " is 

 properly applied only to samples from which a consider- 

 able part of the nitrogenous matter has been removed 

 by steaming. They may be regarded as intermediate 

 between ordinary crushed bones and bone ash. They 

 contain from 60 to 70 per cent, of tricalcic phosphate, 

 and from, 1 to 2 per cent, of nitrogen. The proportion 

 of phosphates is, of course, largest in samples from 

 which the largest proportion of the nitrogenous matter 

 has been abstracted. They are easily ground and are 

 generally obtained in the form of an impalpable powder 

 which can be very thoroughly mixed with the soil, and 

 is easily soluble in dilute acids. 



The powder is very light, and if sown broadcast in 

 windy weather, much of it may be blown away. To 

 avoid this, it is sometimes moistened with water, but a 

 better plan is to mix a quantity of fine damp soil or 

 sawdust with it. 



Bone Ash. This is a purely phosphatic substance 

 not a phospho-nitrogenous manure. When pure it con- 

 sists almost entirely of tricalcic phosphate. The ordinary 

 commercial product contains from 75 to 85 per cent, of 



