224 BOARD OF AGRICULTURE. 



amount of absorbents, cut straw, saw-dust, muck, etc., and the pres- 

 ence of hogs on the manure pile, thus keeping it compact and ex- 

 cluding air, is probably the best method 



BONES. 



One of the earliest substances used as a fertilizer, aside from 

 manures, was bone. Waste bone chips and horn parings were first 

 used about 1750, and later, sa}- about 1780-1800, bones became a 

 comparativel}" common manure in England and Scotland for turnips. 

 An average sample of bone will have the following composition per 

 one hundred pounds: Thirt}' pounds of animal matter containing 

 two and one-half pounds of nitrogen, and seventy pounds of ash 

 containing fifty-eight pounds of phosphate of lime, made up of 

 tweuty-four pounds phosphoric acid and thirty-four pounds of lime, 

 the remaining twelve pounds consisting of magnesia, cai'bonate of 

 lime, etc. 



It was found by various experiments that the phosphoric acid in 

 the bone was the chief cause of the well-known effect of bone fer- 

 tilizers. The first great improvement in the use of bone dates with 

 the introduction of a bone mill, bv which they were reduced to meal. 

 This was in 1814. The next step was the process suggested by 

 Liebig in 1839, by which bones were dissolved with sulphuric acid ; 

 bones thus dissolved, or ''cut," with acid were called superphosphate , 

 and differ from the raw bone in having the greater part of the phos- 

 phate of lime soluble in water, while very little of the lime phos- 

 phate in the raw bone is thus dissolved out when treated with water. 



The term superphosphate should only be applied to a fertilizer 

 containing soluble phosphoric acid, and is not correctly used when 

 applied to the prepared or commercial fertilizers. In 1?43 a new 

 source of phosphoric acid was discovered in Spain. A vein of rock, 

 about seven feet wide, was found there which contained about thirty- 

 four to fifty per cent of phosphoric acid ; in 1844 English farmers 

 tried this new source of phosphoric acid and found it a valuable 

 substitute for bone. 



In the United States bone was first used about 1790. The first 

 bone mill was established in 1830, and superphosphate, or dissolved 

 bone, was first tried in 1851. 



One of the most important geological discoveries in the United 

 States was that of the so-called South Carolina Rock. This rock is 

 found in masses varying from the size of the fist to fragments weigh- 



