INFLAMMABLES. 74. Bitumen. 233 



3. Highly impregnated with ferruginous clay and fulphur, emit- 



ting fulphurous fumes while burning, and leaving a great 

 quantity of ferruginous aflies and cinders. 



4. Cryllallizcd in cubes or 6-fided prifms. 



Found in moll parts of the globe, moft commonly under limc- 

 ftone, fandftone, or fhiftofc clay, forming vaft beds and veins 

 in fecondary mountains, or plains compofed of the fame ma- 

 terials ; frequently in monntains containing lava and columnar 

 bafalts: colour black, more or lefs perfeft : ftains the fingers: 

 burns rather flowly, cakcb more or lefs during combuftion, 

 and does not explode and fly out; fometimes withers and 

 falls to pieces when expofed to the air, loling a portion of its 

 bitumen: fpeciiic gravity from 1,25.10 1,27. 



exygena' Opake, black, very brittle, not ftaining the fingers, burn- 

 ^^^^' ing with little or no fmoke or flame, or flaming with 



iridefcent colours^ leaving a very fmall quantity of 

 whitifli aflies. 



Mineral carbon. Kirivan. miner* 2. p. 53. 

 Kilkenny coal. Thom/on chem» 4. /. 15, 

 Oxygenated carbon. Sonverhy Brit, min, tab, 50. 



1. Of a flaty texture and conchoidal fradure, with a glafly inter- 



nal lullre. Stone coal. 



2. Of a fibrous texture and rather conchoidal fraflure, with 



lefs internal luftre, and often intermixed with powdered 

 carbon, Culm» 



Found in variotis parts of VValeSy particularly round Sijuan/eat 

 and in Ireland^ in ftrata and veins like the former: it burns 

 very llowly, with great heat, without flame or with purple, 

 yellow and white iridefcent colours, and is ignited with 

 much difficulty: during combuftion it emits faint fufi^ocating 

 vapours like charcoal, and is therefore dangerous to ufe in 

 fmall clofe rooms : while burning it explodes and flies about : 

 the culm is confiderably contaminated with powdered carbon 

 which may be ealily rubbed off, ond then it does not ftain 

 the fingers: it contains near 80 per cent, of pure carbon. 

 The ftone-coal is principally ufed for malting, and the culm 

 for burning lime. 



VOL. VIT. — G g 



