202 OF MANURE. 



existed as organic salts in the plants consumed by 

 the animals. 



Fresh bones, wool, hair, hoofs, and horn, are 

 manures containing nitrogen as well as phos- 

 phates, and are consequently fit to aid the process 

 of vegetable life. 



One hundred parts of dry bones contain from 

 32 to 33 per cent, of dry gelatine ; now, supposing 

 this to contain the same quantity of nitrogen as 

 animal glue, viz. 5*28 per cent., then 100 parts of 

 bones must be considered as equivalent to 250 parts 

 of human urine. 



Bones may be preserved unchanged for thousands 

 of years, in dry or even in moist soils, provided the 

 access of rain is prevented, as is exemplified by the 

 bones of antediluvian animals found in loam or gyp- 

 sum, the interior parts being protected by the exte- 

 rior from the action of water. But they become warm 

 when reduced to a fine powder, and moistened bones 

 generate heat and enter into putrefaction ; the 

 gelatine which they contain is decomposed, and its 

 nitrogen converted into carbonate of ammonia and 

 other ammoniacal salts, which are retained in a 

 great measure by the powder itself. (Bones burnt 

 till quite white, and recently heated to redness, 

 absorb 7*5 times their volume of pure ammoniacal 

 gas.) 



Charcoal in a state of powder must be considered 

 as a very powerful means of promoting the growth 



