VI. 



MANURING AND GENERAL MANURES 



127 



Bone ash is imported from South America ; it, of course, is a purely 

 mineral manure, the organic matter having been removed. Occasion- 

 ally, bones are fermented by moistening them with urine and leaving 

 them exposed to the air. 



The following analyses will show the composition of various com- 

 mercial products from bones : 



Another product from bones is bone black, used in decolourising 

 liquids, e.g., sugar syrup ; this consists of about 10 per cent finely 

 divided carbon, mingled with the mineral constituents of bone, often 

 containing 75 to 80 per cent calcium phosphate. It is made by heat- 

 ing bones in closed retorts, and after it has become so clogged with 

 colouring substances as to be useless for decolourising purposes it is 

 used under the name of " spent char " as a manure, especially as it 

 then contains a small quantity of nitrogen. 



Meat meal or meat guano. This is the dried refuse, with bones, 

 from the manufacture of "extract of meat," etc., reduced to fine 

 powder. A similar product is obtained by drying the offal from 

 slaughter-houses, etc., also, in Germany particularly, by drying the 

 carcasses of horses or cattle that have died from disease. Usually the 

 fat and gelatine are first removed by steaming. Various other bye- 

 products, e.g., the refuse from the manufacture of "oleomargarine," 

 and from the manufacture of tallow, are also used for the same pur- 

 pose. These products are usually fairly free from grease and contain 

 their fertilising materials in a readily fermentable form. The following 

 table gives the average contents of valuable ingredients : 



Woollen waste, shoddy manure. After wool has been spun into 

 yarn, woven into a fabric, and worn, the rags are torn to pieces by 



