358 PEAT. 



would not have been the more true. There is no proof 

 that the coal strata have been subjected to the requi- 

 site heat, as there are many reasons for believing the 

 reverse, except in the vicinity of trap; the results in 

 that case forming also an unanswerable objection. An 

 igneous theory requires a pressure sufficient to prevent 

 such an escape of the volatile matters as would leave 

 charcoal remaining; yet having escaped, even in the 

 vicinity of trap, so that the coal is often charred, this 

 should have been a general occurrence. When it is 

 said that the bituminous shales have been thus pro- 

 duced, it is forgotten that these are rare, when they 

 ought to be universal ; while they are easily explained 

 through mixtures of organic matter, perhaps sometimes 

 of bitumen, with clay. But it is a fatal objection, that 

 vegetable fragments could not have been preserved, 

 either in the coal or the associated shales, under the 

 presumed fusion, even of peat or lignite ; as these per- 

 sons also should have remembered that all traces of or- 

 ganization were destroyed, even in their own wretched 

 experiments. Yet if any one will still maintain, with 

 Breislak, that the proper coal series has been exposed 

 to great heat, this will scarcely be asserted of the 

 oolithe and the green sand, in which the lignites are 

 perfect coal. Yet I am indifferent though this were 

 proved: since, were the coal even fused, like the jet in 

 my experiment, it was already coal chemically, as this 

 was bituminous, and from the same cause. Yet there 

 should then be no shells in the limestones of that se- 

 ries ; since I have proved that they are obliterated by 

 such a heat. 



There remains therefore no agent but pressure, uni- 

 ted to the action of water ; equivalent, surely, to the 

 effects, when it has converted clay into shale, and cal- 

 careous mud into limestone. I formerlv showed how 



