FORMATION OF WOOD COAL. 340 



its oxygen. The proportion of these numbers is expressed by 

 the formula C 33 H 2 1 O ia .* 



When these numbers are compared with those obtained by 

 the analysis of oak, it would appear that the brown coal was pro. 

 duced from woody fibre by the separation of one equivalent 

 of hydrogen, and the elements of three equivalents of carbonic 

 acid. 



1 atom wood C36 H 2 20 2 2 



Minus 1 atom hydrogen and 3 atoms car- > n H n 

 bonicacid . . . .5 C » ** lU 8 



Wood Coal . Cj 8 H 91 Ou 



All varieties of wood-coal, from whatever strata they may be 

 taken, contain more hydrogen than wood does, and less oxygen 

 than is necessary to form water with this hydrogen ; conse- 

 quently they must all be produced by the same process of decom- 

 position. The excess of hydrogen is either hydrogen of the wood 

 remaining in it unchanged, or it is derived from some exterior 

 source.. The analysis of wood-coal from Ringkuhl, near Cassel, 

 where it is seldom found in pieces with the structure of wood, 

 gave, when dried at 212°, 



Carbon . . . 62*60 . 

 Hydrogen . . 5 02 



Oxygen . . . 26*52 . 

 Ashes . . 5'86 



10000 10000 



The proportions derived from these numbers correspond very 

 closely to the formula C 32 H l5 () 9 , or they represent the con- 

 stituents of wood, from which the elements of carbonic acid, 

 water, and 2 equivalents hydrogen, have been separated. 



C 8 « H 22 22 =Wood. 

 Subtract C 4 H 7O1 3 =4 atoms carbonic acid + 5 atoms of water 

 +2 atoms of hydrogen. 



C l2 H u O 9 =Wood Coal from Ringkuhl. 

 * The calculation gives 57-5 carbon, and 5-98 hydrogen. 



