ON COAL. 



^31 



6. Black-coal occurs in concentric lamellar con- 

 cretions, — a character which points out its crystal- 

 line nature. 



7. Some varieties of black-coal appear to have a 

 determinate form, thus indicating their deposition 

 from a state of solution. 



8. The vegetable origin of brown-coal is shewn 

 by its whole mass being either entirely composed 

 of vegetable remains, or by those remains occur- 

 ring in it in a preponderating quantity. 



