201 



essay. He supposes the origin of the coal to be from a ferment- 

 ation and consequent eremacausis of vegetable matter ; others 

 suppose this vegetable matter to have been chiefly mosses, such 

 as form the large accumulations of peat. My view is, that coal 

 is chiefly composed of resinous trees, (Conifers,) and Oleaginous 

 trees, (Palms,) these latter being in excess in the Cannel coal. 

 I now wish to show, that all coal has been formed from nearly 

 the same original materials, and probably nearly under the same 

 circumstances, from the Anthracite to the most bituminous. 

 This 1 propose to do by exhibiting these specimens, selected 

 from many hundreds in my possession, of Anthracite coal from 

 Pennsylvania, of bituminous coal from the Cumberland basin, 

 and from Hillsboro' ; specimens from Pictou and other localities 

 might have been added. The comparison of these, the exact 

 similarity in their structure, marks of organisms, and peculiar 

 fracture, can leave but little doubt on the subject ; they exhibit, 

 however, but a small portion of the resemblances manifest on a 

 minute and extended investigation. 



From what cause then can arise the difference in various 

 coals? At present only three characters of diversity are appa- 

 rent. 



Specific gravity, quantity of carbon, and quantity of hydrogen : 

 to show this the descending scale may be used thus : — 



The difference in specific gravity and carbon would seem to 

 depend on the diminution of the hydrogen. How this has been 

 separated, whether by a process of time, of pressure, of heat, or, 

 as is most probable, by a process of which we are entirely igno- 

 rant, must be a subject for future investigation. 



It must be obvious that the foregoing is but a very faint out- 

 line of some of the results of my yet imperfect examination of 

 this subject, imperfect mainly because the means of a more per- 

 fect one are yet out of reach. The chemical analyses of coal 

 have hitherto been undertaken chiefly with commercial views, 



