108 MODERN SCIENCE READER 



to checked decay when covered with water, and it is the 

 latter process which is the most valuable in converting it 

 into a form which is available for fuel. 



When decomposing matter is freely exposed to moist air, 

 processes of fermentation and still further oxidation con- 

 vert it ultimately into carbon dioxide and water vapor, 

 leaving as a residue only the mineral matters and more 

 resistant hydrocarbons, the latter in turn also disappearing, 

 and it is by such processes of decay that Nature cleanses 

 the surface of the earth from all waste vegetable matter. 

 When, however, the dead vegetation has its decay checked 

 by immersion in water or the deposition over it of silt or 

 soil of such a character as to cut off from it the supply of 

 atmospheric oxygen, the processes of decay continue, but 

 instead of exterior oxygen acting on the decomposing 

 molecules, the changes that take place are restricted to 

 those set up between the constituents of the molecule itself, 

 and result in the elimination of carbon dioxide, water, and 

 methane, with consequent lowering of the proportion of 

 hydrogen and oxygen left in the residue. 



Enormous areas of peat exist at the present day not 

 only in the British Isles, but in even greater quantities in 

 Russia, Sweden, Norway, Germany, and Finland, while in 

 Canada and America the peat bogs are still more vast, and 

 in the future this material will probably play an important 

 part in the supply of fuel when the depletion of our coal 

 supplies drives us to utilize these natural stores. 



The great interest, however, attaching to peat at the 

 present moment is that the same action which converts 

 cellulose into peat will, if continued under conditions of 

 considerable pressure and higher temperatures than ordi- 

 narily exist at the present clay, convert the peat deposits 

 into a coal seam. 



Taking the luxuriant vegetation of the carboniferous era, 

 it is easy to imagine the way in which the huge peat bogs 

 were formed in the low-lying watersheds, and in which the 

 agglomeration of vegetable matter swept down by the hur- 



