BITUMEN. 85 



heat and very little smoke. Contains 90 to 95 per cent, of 

 carbon. 



Bituminous CoaL 



Has a rather more waxy appearance than anthracite. 

 Colour, black. Streak, blackish. S.G-. not more than 1/5. 

 Varieties : pitching or caking coal, splint coal, cannel coal 

 (having a fine compact texture and conchoidal fracture, 

 capable of receiving a good polish, sonorous when struck), 

 cherry coal, jet (which is blacker than cannel coal but more 

 brilliant in lustre), contains 73 to 90 per cent, of carbon. 



Brown Coal or Lignite. 



Colour, brown or blackish. Eesinous lustre, sometimes 

 dull. 50 to 90 per cent, carbon. Although in England and 

 many other countries the carboniferous rocks contain large 

 coal beds, the most useful mineral is met with in other 

 formations, such as in New Zealand, where lignite is found 

 of a recent as well as of the Jurassic or Cretaceous age. In 

 various parts of North America the lignite-bearing strata 

 belong to the Tertiary and Cretaceous period, &c. Coal 

 occurs in oolitic rock in India and Virginia (North America). 



BITUMEN. 



Found both in the solid and fluid state. Is inflammable 

 and has a peculiar odour. 

 Varieties : 



Asphalt. 



A solid black or brownish mineral. Fracture, conchoidal 

 with glassy lustre. H. 2. When pure, will float on water. 

 In Trinidad there is a lake of it 1 miles in circumference. 

 It is solid near the edges, but boiling in the centre. Asphalt 

 is found in the mountain limestone of Derbyshire and 

 Shropshire, also in granite with quartz and fluor-spar in 

 Cornwall. 



Naphtha (mineral oil). 



A fluid of a yellowish colour. Has a peculiar odour. 

 Will float on water. 



