836 ANNUAL, REPORT OF THE Off. Doc. 



RAW BONE, GROUND BONE OR BONE MEAL A^D DISSOLVED BONE. 



Animul bones are composed of two distinct substances, which 

 interpenetrate one anotJier. There is a sort of- frame-work of earthy 

 matter, which is a substance containing- much nitrogen. Raw bones 

 are, therefore, doubly valuable for manurial purposes, because they 

 contain both phosphoric acid and nitrogen. As ordinarily collected, 

 bones contain from 50 to 60 per cent, of phosphate of lime and 

 from 5 to 7 per cent, of nitrogen. Fresh raw bones also contain fat, 

 and this is not only useless as a plant food, but it adds weight to 

 the bone and makes it hard to grind, and, when ground, the more 

 fat remaining in the bone the slower will be the decomposition in 

 the soil. To obviate this difificulty, bones are generally steamed, 

 or carried through some process to remove the fat, before they are 

 ground for fertilizers. Steamed or dessicated bones, if not too 

 strongly steamed, are better for fertilizer than raw bones. Some 

 nitrogen is lost by this i)rocess, but if carefully done, the gain 

 exceeds the loss. Bone meal is obtained by grinding the crude or 

 steamed bones, and it is valuable in proportion to the degree of 

 fineness to which it is reduced. According to its fineness, it is 

 variously called ground bone, bone meal, flour of bone and bone dust. 

 The finer it is, if used without acid, the easier it decays or dissolves 

 in the soil, and the sooner the chemistry of nature converts the (tri- 

 calcic) phosphate of lime to a form available to plants. Good 

 ground bone or bone meal should contain from 20 to 25 per cent, of 

 phosphoric acid and from 3 to 4 per cent, of nitrogen. 



The demand for bones for use in various arts and especially in 

 refining sugar, is making this form of fertilizing material com- 

 paratively scarce in the market and correspondingly high in price. 

 If rates advance much, it will become unprofitable for farmers to use 

 bone fertilizers for their phosphates. The same causes lead to the 

 considerable adulteration of bone meal that is now found. Lime, 

 gypsum, coal aishes, ground oyster shells, crab shells and like ar- 

 ticles are used for this purpose as well as the less objectionable 

 mixing of fine-ground rock phosphate, all being sold under the name 

 of bone. When bone, ground bone or bone meal is treated with sul- 

 phuric acid, the product is the dissolved bone of our markets, also 

 knowm as acidulated bone, soluble bone and dissolved bone phos- 

 phate. This is simply an acid phosj)hate or super-phosphate, made 

 from bones. 



BONE BLACK AND DISSOLVED BONE BLACK. 



When broken bones are placed in a retort or iron cylinder, the 

 air being excluded, and then strongly heated, gas, water, oily matters 

 and other products are driven off, while black bone charcoal is left. 



