“^ygena- 
INFLAMMABLES. 74.* Bitumen. 233 
■; Highly iroptegndted with ferruginous clay and fulphur, emit- 
ting fulphurnus fumes while burning, and leaving a great 
quantity of ferruginous afties and cinders. 
4. Cryftallizcd in cubes of 6.fidcd prifms* 
Foun-^ =n moft parts of the globe, moft commonly under litne- 
ftone, fandllone, or fhiibfe cla^, forming vaft beds and veins 
in fecondary mountains, or plains compofed of the lame ma- 
terials) frequently in montitains containing lava and columnar 
bafa’ts- colour black, more or lefs perfeft: (tains the fingers: 
burns rather fiowly, cakes more or lefs during combullion, 
and does not explode and fly out: fomctimes withers and 
falls to pieces when expofed to the air, loling a portion of its 
bitumen: fpecific gravity from 1,25.10 1,27. 
Opaicc) black, very brittle, not ftaining the fingers, burn- 
ing with little or iio fmoke of flame, or flaming with 
iridefeent colours, leaving a very fmall quantity of 
whitifh afties. 
Mineral carbon. Kirnuatl. miner. 2 i p. 534 
Kilkenny coal. Thomfon chem, 4. pi ij- 
Oxygenated carbon. Soiwerhy Brit. min. tab. 50. 
1. Of a flaty texture and conchoidal fraflure, with a glafl'y inter- 
nal lullre. Stone coal. 
2 Of a fibrous texture and rather conchdidal frafturej with 
lefs internal luflrej and often intermixed with powdered 
carbon. Culm. 
Found in various parts of Wales, particularly round Snisanfea, 
and in Ireland, in llrata and veins like the former: it burns 
very llowly, with great heat, without flame or with purple, 
-ellow and white iridefeent colours, and is ignited with 
much difficulty : during eombuftion it emits faint fuffocating 
vapours like charcoal, and is therefore dangerous to ufe in 
fmall clofc rooms : while burning it explodes and flies about ; 
the culm is confiderably contaminated with powdered carbon 
which may be eafily tubbed off, bnd then it does not ftain 
the fingers : it contains near 80 per cent, of pure carbon. 
The ftqne-coal is principally ufed for malting, and the culm 
for burning lime* 
VOL. VII. — G g 
