VEGETABLE OBI GIN OF COAL. 437 



on the place of its growth, or conveyed to estuaries or the 

 mouths of rivers, and sunk in spots alternately occupied by 

 fresh and salt waters, where, under the influence of heat gene- 

 rated by chemical action, and the pressure of the mud, sand, 

 or clay deposited by these streams, the vegetable masses have 

 been converted into coal. The agency by which this result has 

 been effected is supposed to have been analogous to the che- 

 mical process by which vegetable matter is known to ferment 

 and produce spontaneous combustion. If hay be stacked in a 

 moist condition, or too closely packed, fermentation and igni- 

 tion are produced, and the mass is consumed; if the process 

 be interrupted and combustion prevented, the hay is found 

 to have acquired a dark brown colour, a glazed or oily surface, 

 and a bituminous odour. The same phenomena are observed 

 in the case of flax, which if packed and pressed in a damp 

 state, is liable to the same results; all vegetable substances, 

 under like conditions, being exposed to similar chemical 

 changes. Were any vegetable matter, in a moistened state, 

 placed beneath great pressure, so as to prevent its gaseous 

 elements from escaping, bitumen, lignite, or coal would be 

 produced during the various stages of the process. Vege- 

 table matter has been traced through every stage of the 

 saccharine, vinous, acetous, and bituminous fermentation; 

 and alcohol, ether, naphtha, petroleum, bitumen, lignite, jet, 

 coal, amber, and even the diamond, have been ascertained 

 to be of vegetable origin. 



EXPERIMENTS OF GOPPERT. The experiments of Pro- 

 fessor Groppert, of Breslau, which have been followed in this 

 country, would alone be sufficient to establish the vegetable 

 origin of coal, even if it were not already proved beyond the 

 possibility of a doubt. Having observed that the leaf, in iron- 

 stone nodules, might occasionally be separated, in the form 

 of a carbonaceous film, he placed fern-leaves in clay, dried 

 them in the shade, exposed them to a red heat, and thus 

 obtained striking resemblances to fossil plants. According 

 to the degree of heat, the plant was found to have become 

 either brown, shining, black, or to be entirely lost, the 

 impression only remaining; but in this latter case, the 

 surrounding clay was stained black, thus indicating that 

 the colour of the coal-shales is derived from the carbon of 

 the plants which they include. 



