DR TRAILL ON THE TORBANEHILL MINERAL. 9 



6. Three sorts of Capeldrae coal. 



7. Two sorts of Lochgelly parrot coal. 



8. Duke of Hamilton's Lesmahago cannel or parrot coal. 



9. Mr Ferguson's parrot coal. 



10. Kings wood parrot coal. 



11. Cowdenhillhead parrot coal. 



12. West Weniyss Hums, which is little better than a bituminous shale. 



Mineralogists distinguish mineral species chiefly by what are termed external 

 characters, aided by a few simple chemical results. 



The Torbanehill mineral differs in mineralogical characters from all these ; 

 especially in having some degree of translucency on the edges, when examined in 

 thin fragments by a strong light ; in having a streak not shining, but dull ; and 

 which is strongly coloured of a pale ochre-yellow hue ; whereas every coal has a 

 shining streak, which is not changed in colour. The fracture, too, of every coal 

 affording an abundant gas, as Bitumenite does, is glistening or shining ; but the 

 fracture of Bitumenite is perfectly dull. Coal is brittle, or easily broken ; but 

 Bitumenite, though it split readily in the direction of the bed, is not easily fran- 

 gible in a cross direction. When so struck with a hammer, it resists, and shews 

 very considerable elasticity, causing recoil of the hammer ; as was remarked both 

 by Mr Wood and me when procuring specimens of the mineral at the three pits. 

 It has been formed into snuff-boxes in the turning-lathe ; but it does not take a 

 polish, and looks dull from this circumstance. 



When moderately heated, Bitumenite catches fire almost as readily as as- 

 phalt, and burns with a dense white flame, emitting much smoke ; but the flame 

 dies away without igniting the mass. In fact, when burnt by itself in a grate, this 

 mineral scarcely produces the glow of ignition, and neither fuses or cakes like every 

 bituminous coal, nor forms cinders ; but it leaves a very white mass of nearly the 

 form of the fragments put into the grate ; which mass, however, is very brittle, 

 and easily reduced to a fine powder. It therefore is deficient in one important 

 quality of common coal, that of forming a bright ignited mass, calculated for the 

 roasting of meat, or for completing other culinary operations by radiant heat. 



It is distinguished from asphalt by its streak, its tenacity, and by not melting 

 when heated before it inflames. 



The Torbanehill mineral is distinguished from bituminous shale by its streak, 

 its tenacity, its cleavage, by its far more ready inflammability, and by the smaller 

 proportion of its earthy residue when burnt, as well as by its far more abundant 

 yield of inflammable gas. 



On analyzing three different specimens of Bitumenite, I found the proportion 

 of volatile and fixed ingredients somewhat different in each. 



