AND OTHER VARIETIES OF COAL. 125 



many coal-beds, no crystalline or other aggregation of earthy 

 matter is detected by the microscope ; and yet chemistry de- 

 termines the presence of a considerable amount per cent, of 

 such matter. In such cases, I believe, the earthy matter has 

 been added to the vegetable part in a state of solution, or 

 fine molecular subdivision ; whilst, where in other instances 

 crystals and earthy particles of considerable size occur, it is as 

 plain that many of these have been deposited as such origi- 

 nally, as is likely to be the case in the instances in which 

 beds of coal are formed in the beds of large rivers. 



I will now endeavour to state very briefly the facts which 

 I believe to have been made out in this investigation, with the 

 conclusions which, I think, they warrant, as to the nature of 

 the Torbanehill coal. 



1st. That the whole seam is laminated — a sufficient expla- 

 nation of its tendency to split horizontally, and of its slaty 

 fracture. 



2nd. That it abounds in fossil plants, especially Stigmarise, 

 which present well-preserved scalariform tissue on their sur- 

 face, in whatever part of the bed they appear. 



3rd. That the small angular facets, seen in different planes 

 on every fractured surface, are produced by vegetable tissues, 

 easily recognised under low powers of the microscope. 



4th. That small blocks examined as opaque objects with 

 low powers present rounded yellow spots on their upper and 

 lower surfaces, and elongated yellow spots on their sides and 

 ends, bounded by dark-brown matter — appearances which are 

 produced by circular masses of yellow matter flattened ver- 

 tically. 



5th, That thin sections, made horizontally, show rounded 

 yellow patches, often lobed ; but similar sections, made ver- 

 tically, show yellow spots, elongated in the direction of the 

 laminae. These yellow spots are bounded by dark matter, in 

 great part made up of fragments of vegetable fibre and mem- 

 brane. The addition of heat drives off the yellow matter as 

 gas, and leaves polygonal spaces, like the remains of vege- 

 table cells, in the mass generally, and in some of the yellow 

 bodies. 



6th. That, besides the circular-flattened yellow bodies, 

 there are much smaller polygonal and flattened bodies of the 

 same colour, more uniform in diameter, sometimes with double 

 walls, resembling vegetable cellular tissue. 



7th. That other appearances, such as would be produced 

 by masses of vegetable tissue sending off fibres or membranes 

 into the spaces between tj^e yellow bodies, to constitute their 

 boundaries, occur here "and there in the mass, confirming the 



