BONES. 221 



tained from its sale as a manure, it will seldom hap- 

 pen that farmers can enjoy an opportunity of apply- 

 ing it extensively to the cultivation of the soil. 

 Wherever it is offered in the market, certain and re- 

 liable information as to its nature and quality ought 

 always to be sought from a chemical examination.* 



* There are two kinds of sugar-refuse : — 1st. Bone-black, which, 

 after many times reburning, has at length lost so much of its power of 

 decoloring brown sugar, that its use is no longer economical to the su- 

 gar-refiner. This is partly in a fine granular and partly in. a powdery 

 state, but dry. It may be here remarked, that, theoretically, fire ex- 

 erts no action on, or rather produces no change in, phosphate of lime ; 

 therefore this ingredient of bones, however often passed through the 

 bone-burner's retort, remains essentially, and to all purposes, the same 

 phosphate of lime as that originally found in the raw bone. Conse- 

 quently it is as good for the manufacture of superphosphate of lime 

 as ever, although in practice the acid in sugar acts on a small portion 

 of the phosphate or carbonate, causing some loss. 



Besides the phosphate of lime, however, a portion of this dry sugar- 

 refuse consists of the 33 per cent, organic matter of the table on the 

 next page, carbonized, — of itself then a valuable addition to the sub- 

 stance, as it is a powerful absorbent of ammonia. This ingredient in 

 burning suffers also some diminution. 



This dry refuse, particularly the fine powdery part, therefore, is a 

 highly beneficial ingredient of the compost-heap. I have found great 

 benefit from spreading it alone on a sandy, light-colored soil, although 

 I much prefer adding it with other ingredients to the compost. 



2d. The sugar-refiner's Scum. This is fine bone-black mixed with 

 all the impurities separated from the sugar during its clarification, and 

 contains the greater part of the substances used in clarifying sugar. 

 It is in a pasty, sticky, or hard-compressed state. When this is in 

 heaps it begins to ferment, and produces a burning heat with injurious 

 acids, and a considerable quantity of sulphuretted hydrogen gas es- 

 capes. In this state it is very hurtful to vegetation ; trees, and 

 other vegetation, have been completely destroyed by it. Under prop- 

 er management it is, however, very valuable in agriculture, and the 



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