MANURES. 95 



CHAPTER IY. 



ABSORBENTS. 



BEFORE considering further the subject of animal 

 excrement, it is necessary to examine a class of ma- 

 nures known as absorbents. These comprise all mat- 

 ters which have the power of absorbing (or soaking 

 up) the gases which arise from the evaporation of 

 solid and liquid manures, and retaining them until 

 required by plants. 



The most important of these is undoubtedly clay, 

 which forms a large part of nearly all fertile soils. 

 The use of this in connection with manure will be 

 spoken of in describing the treatment of night-soil. 

 For ordinary use one of the most valuable absorb- 

 ents is charcoal. 



CHARCOAL. 



Charcoal, in an agricultual sense, means all forms 

 of carbon, whether as peat, muck, charcoal dust from 

 the spark-catchers of locomotives, charcoal hearths, 

 rirer and swamp deposits, leaf mould, decomposed 

 spent tanbark or sawdust, etc. In short, if any veg- 

 etable matter is decomposed with the partial exclu- 

 sion of air (so that there shall not be oxygen enough 

 supplied to unite with all of the carbon), a portion 

 of its carbon remains in the exact condition to per- 

 form the best agricultural offices of charcoal. 



The operation of carbonaceous matter in the soil 



