316 ANNUAL OF SCIENTIFIC DISCOVERY. 



protuberance formed by the vessels which penetrate the bark, and 

 depressions on each side thereof, to which the impressions of these in 

 the Shale, although faint, bear a close resemblance. In many of the 

 leaves of the recent fir tribe, there are rows of glands extending from 

 the base to the summit, and in some, very minute spines on each edge. 

 It cannot be expected that these microscopic characters should be visi- 

 ble in impressions on so coarse a material as the Shale, but no doubt 

 they will be found when similar impressions are discovered in the 

 coal jtself. 



Other impressions of leaves of conifer* are in my collection, some 

 in the anthracite ; but although I have no doubt of their being leaves, 

 they are not so undeniable as to be exhibited as proofs. I pass on to 

 the chemical evidence. Lehmann states ihatformic acid is found in coal 

 during the process of decay (eremacausis), and also that is found in 

 the berries of the Juniperus and the cones of several of the fir tribe. 

 Kedtenbacher finds formic acid in the leaves and twigs of the fir tribe 

 during fermentation (incipient eremacausis.) A few years ago, 

 Pelletier and Walther examined the tar produced by the distillation 

 of resin, and found therein two substances which they named 

 retinnaptha and retinnyle, and then the well-known napthaline. The 

 progress of organic chemistry has since shown the two former sub- 

 stances to be the Toluole and the Cumole of the present day. I will 

 now simply advert to the opinion of Goppert, in his prize essay. He 

 supposes the origin of the coal to be from a fermentation and conse- 

 quent eremacausis of vegetable matter. Others suppose this vegetable 

 matter to have been chieily mosses, such as form the lar^e accumula- 



r. J 



turns ot peat. 



My view is that coal, is chiefly composed of resinous trees, (Conifers) 

 and oleaginous trees, (Palms) the 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 circum- 

 stances, from the anthracite to the most bituminous. This I propose 

 to do by exhibiting these specimens, selected from many hundreds 

 in my possession, of anthracite coal from Pennsylvania, of bituminous 

 coal from Cumberland basin, and from Hillsboro'; specimens from Pic- 

 tou and other localities might have been added. The comparison of 

 these, their 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 apparent : specific 

 gravity, quantity of Carbon, and quantity of hydrogen. To show 

 this, the descending scale may be used thus : 



