64 FERTILIZERS. 



in hills where cabbage-seed had been planted, they soon 

 softened into a soap-like mass. If the gelatine is taken 

 from them, with it they lose all the nitrogen ; and there- 

 fore their value as a fertilizer is to be measured solely 

 by the phosphoric acid which they contain, and this, I 

 think, would be classed with the form known as "in- 

 verted." Oil or grease in any form is not plant-food, 

 hence the loss of this is no loss to the fa*mer. As has 

 been stated, bones exposed to the weather lose more or 

 less of their nitrogen, and therefore are not so valuable 

 for fertilizing purposes. Professor Johnson states that 

 bone char is a little more certain as a fertilizer than finely 

 ground phosphate rock when the latter is applied to the 

 soil in its crude state, but it needs treating with oil of 

 vitriol to get from it the best results. 



REDUCTION OF UNGROUND BONE. 



Professor Johnson, in the report of the Connecticut ex- 

 periment station for 1881, gives several methods for the 

 reduction of unground bones, from which I make the fol- 

 lowing extract: "If whole bones are treated with acid, 

 suitably diluted, it acts energetically on the bones at first, 

 and readily disintegrates them to a certain depth : unless, 

 however, a large excess of acid be used, the action soon 

 becomes sluggish, because, where the acid is in contact with 

 the bone, it forms sulphate of lime. Fresh acid must, then, 

 be brought in contact with the bone by abundant stirring, 

 in order to renew and maintain the action. The excess of 

 sulphuric acid rapidly absorbs moisture from the air : and 

 the final result is, the solution of the bone, or most of it, at 

 an expense of a wasteful excess of acid ; while the product 

 requires moisture, with something to take up the water, 

 and neutralize the excess of sulphuric acid. 



" On a small scale, cast-iron vessels could be employed. 



