PEAT MOSS. 267 



plants, the chief of which is bog moss (Sphagnum}. " Mosses 

 of this genus grow in very wet situations and throw out 

 new shoots in their upper parts whilst their lower parts are 

 decaying and being converted into peat, so that shallow pools 

 are gradually converted into bogs .... The formation 

 of peat takes place only in the colder parts of the world. In 

 warm regions the decay of vegetable substances after life has 

 ceased, is too rapid " (Chambers' Encyclopedia}. Besides bog 

 moss, we find among peat-producers, cotton-grass (Eriophorum 

 angnstifoliiuri) and other sedges, hor.se-tails (Equisetum\ 

 heaths, and bog myrtle (Myrica gale). Drainage kills almost 

 all bog plants. Peat is the first stage in the formation of 

 ordinary coal ; brown coal (lignite] being an intermediate one. 

 The successive changes undergone by woody fibre, peat and 

 lignite in the formation of coal, consist of a " peculiar decom- 

 position or fermentation of buried vegetable matter, resulting 

 in the separation of a large proportion of its hydrogen in the 

 form of marsh-gas (CH 4 ), and similar compounds, and of its 

 oxygen in the form of carbonic acid gas (CO 2 ), the carbon 

 accumulating in the residue. Thus, cellulose (C 6 H 10 O 5 ), 

 which constitutes the bulk of woody fibre, might be imagined 

 to decompose according to the equation 2C 6 H 10 O 5 = 

 5CH 4 + 5 CO 2 + C 2 " (Bloxam\ The conversion of bog 

 plants into peat, somewhat resembles that of wood into 

 charcoal, when it is burned in the presence of a narrowly 

 limited supply of air. 



The following table shows the respective percentages of 

 carbon, hydrogen and oxygen in wood, peat, lignite, ordinary 

 coal and anthracite : 



Carbon. Hydrogen. Oxygen. 



Wood . . . 100 12. 18 83.07 



Peat . . . 100 9.85 55-67 



Lignite . . 100 8.37 42.42 



South Wales coal . 100 4.75 5.28 



Anthracite . . 100 2.84 1.74 



