I90 REINHARDT THIESSEN 



to the one represented. It will be noticed that the woody patches, 

 about one-half natural size in the photograph, are all relatively 

 small and that in many cases the sides running parallel to the 

 direction of the wood fiber form approximately straight lines, while 

 the sides cutting across the fibers are irregular. Rounded and 

 very irregular patches are not uncommon. The condition so 

 clearly expressed in the Vandalia coal is common, in a more or less 

 varying degree, to all the ordinary bituminous coals thus far 

 examined. The example given may, therefore, well serve as a 

 representative type common to all ordinary bituminous coals, 



The patches are solid components. — ^The question at once arises. 

 Are the woody patches, universally seen on the horizontal cleavage 

 surfaces, merely the impressions of some woody fragments that 

 have long since disappeared or are they actual constituents or 

 components of the coal ? 



It is not difficult to show that the woody patches represent 

 solid masses on the one or the other side of the cleavage surface. 

 There is, however, for each such component a counterpart patch 

 in the corresponding cleavage surface, which is an impression. On 

 cutting with a fine, sharp tool into the patch representing the 

 component, a thin glistening layer of coal is found immediately 

 underneath the surface over the entire patch. Also when a lump 

 of coal is submitted to Schulze's maceration reagent for a certain 

 length of time it may be brought into a condition in which it 

 readity separates into numerous thin, scaly fragments. Many of 

 these bear the woody structure on both sides and when broken 

 show glistening, glassy, jet black coal in the interior. Or, after a 

 treatment for a certain length of time with this reagent, a small 

 lump of coal may be dissected and there may be isolated small 

 sheets or scalelike masses bearing woody marks on the surfaces 

 and consisting of bright glistening coal in the interior. 



In splitting a lump of coal it is very rare that the fracture runs 

 through the middle of these thin components, but almost always 

 along one of its surfaces. The larger components of bright coal or 

 larger anthraxylon elements, on the other hand, almost always split 

 through the interior, exposing gHstening jetty coal of the same 

 appearance as that in the thin components. 



