GROUND BONES AS FERTILIZERS. 379 



gen, which is more than is claimed in most of the ammoniated 

 superphosphates. This fact finds its explanation in the cir- 

 cumstance that the softer bones, those that contain the largest 

 proportion of nitrogenous matter, are mainly used for fertiliz- 

 ing purposes. The harder bones bring a better price in other 

 branches of industry. The reduction in value which the ren- 

 dered bones suffer — in consequence of a partial abstraction of 

 nitrogenous matter — is, to some extent, at least, compensated 

 for by the softening and disintegration of the bone-phosphate, 

 and thus improved solubility of the phosphoric acid. To 

 abstract the fat from the bones before they are worked into 

 fertilizers is not only good economy, but the absence of fat 

 tends to hasten their solution under the influence of moisture 

 and carbonic acid. As each manufacturer is apt to follow his 

 own notion about rendering the bones, — there are cases on 

 record in which the nitrogen has been noticed as low as from 

 1 to 2 per cent, and the phosphoric acid as high as 28 per 

 cent., — it becomes essential that each establishment should 

 state, within proper limits, the guaranteed. composition of its 

 own articles. Whenever the percentage of nitrogenous matter 

 becomes low in ground bones, they act more slowly on the 

 crops than otherwise. For this reason, it is quite judicious to 

 compost them for some weeks, under proper precaution, with 

 some organic matter, before they are used. Good authorities 

 recommend adding an equal volume of sawdust, or, what is 

 still better, horse or sheep dung, and keeping the mixture for 

 a few weeks in a moist state fit for fermentation, within a 

 sheltered place, after covering it carefully with a layer of 

 earth of from four to five inches in thickness. 



Whenever a special application of phosphates is desirable, 

 this course no doubt deserves a recommendation. In general 

 farm management, good results will be secured by incorporat- 

 ing gradually a certain amount directly into barnyard 

 manure. 



Next to chemical composition, ought their mechanical con- 

 dition to be considered. The finer ground bones give sooner 

 good results, and thus return the best interest on the invest- 

 ment ; they sell, according to the fineness of granulation, from 

 $35 to $50 per ton in the retail trade. 



