*r,2 CONVERSION OF WOOD 



acid gas, and are very seldom intermixed with combustible 

 gases. 



Wood-coal from the middle bed of the strata at Ringkuhl gave 

 on analysis 65*40 — 64*01 carbon, and 4*75 — 4-76* hydrogen ; 

 the proportion of carbon here is the same as in specimens 

 procured from greater depths, but that of the hydrogen is much 

 less. 



Wood and mineral coal are always accompanied by iron 

 pyrites (sulphuret of iron) or zinc blende (sulphuret of zinc) ; 

 which minerals are still formed from salts of sulphuric acid, with 

 iron or zinc, during the putrefaction of all vegetable matter. It 

 is possible that the oxygen of the sulphates in the layers of wood- 

 coal is the means by which the removal of the hydrogen is 

 effected, since wood-coal contains less of this element than wood. 



According to the analysis of Richardson and Regnault, the 

 composition of the combustible materials in splint coal from 

 Newcastle, and cannel coal from Lancashire, is expressed by the 

 formula C 24 H l8 O. When this is compared with the composi- 

 tion of woody-fibre, it appears that these coals are formed from 

 its elements, by the removal of a certain quantity of carburetted 

 hydrogen and carbonic acid, in the form of combustible oils. 

 The composition of both of these coals is obtained by the subtrac- 

 tion of 3 atoms of carburetted hydrogen, three atoms of water, 

 and 9 atoms of carbonic acid from the formula of wood. 



:WOO(l 



3 atoms of carburetted hydrogen Cj H 6 

 3 atoms of water . . . H 3 O 3 

 9 atoms of carbonic acid . C 9 O 1 8 



Mineral coal 



Ci 2 H 9 2 

 C 24 H, 3 



Carburetted hydrogen generally accompanies all mineral coal ; 

 other varieties of coal contain volatile oils which may be sepa- 

 rated by distillation with water. (Reichenbach.) This origin of 

 naphtha is owing to a similar process of decomposition. Caking 

 coal from Caresfield, near Newcastle, contains the elements of 

 cannel coal, minus the constituents of olefiant gas C 4 H 4 . 



• The analysis of brown coal from Ringkuhl, as well as all those of the 

 same substance given in this work, have been executed in this laboratory 

 fey M. Khtinert, of Cassel. 



