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tence. Bitumen is composed of 

 carbon and hydrogen. It appears 

 that formerly bitumen was general- 

 ly used instead of mortar, and 

 authors suppose that the tower of 

 Babel, the walls of Babylon, of 

 Sodom, and other places, were 

 built of bricks cemented together 

 by bitumen, and that the ark of 

 Noah, and the vessel of bull-rushes 

 in which Moses was exposed, were 

 coated with this substance. Bitu- 

 men, when fluid, has been called 

 by some Latin writers, oleum vi- 

 vum. Lyell says that the tar-like 

 substance, which is often seen to 

 ooze out of the Newcastle coal 

 when on fire, and which makes it 

 cake, is a good example of bitumen. 

 Mr. Hatchett says "we may, with 

 the greatest probability, conclude 

 that bitumen is a modification of 

 the resinous and oily parts of vege- 

 tables, produced by some process of 

 nature, which has operated by slow 

 and gradual means on immense 

 masses, so that, even if we were 

 acquainted with the process^ we 

 should scarcely be able to imitate 

 the effects, from the want of time, 

 and deficiency in the bulk of the 

 materials. But although bitumen 

 cannot at present be artificially 

 formed from the resinous and other 

 vegetable substances by any of the 

 known chemical processes, yet there 

 is every reason to believe that the 

 agent employed by nature in the 

 formation of coal and bitumen has 

 been either muriatic or sulphuric 

 acid." The varieties of bitumen 

 will be separately described under 

 their different names. Parkinson. 

 Lyell. Bakewell. 



BITU'MINATED. (bitummatus^ Lat.) 

 Prepared with bitumen; impreg- 

 nated with bitumen. 

 BITTTMINI'FEROUS. Yielding bitumen ; 



containing bitumen. 

 BITT/MINISE. To prepare with, or 

 coat with, bitumen. 2. To convert 

 into bitumen. 



BITUMINISA'TION. The preparing, or 

 impregnating, with bitumen. 



BITTJMINIOTTS SHALE. (The Brands- 

 chiefer of Werner : le schiste 

 bitumnieux of Brochant : schiste 

 argileuxbitumineux of Brongniart.) 

 An argillaceous shale, much im- 

 pregnated with bitumen, very com- 

 mon in the coal measures. A 

 blackish-brown, or greyish, sub- 

 variety of shale; fracture slaty; 

 usually soft and unctuous to the 

 touch. Specific gravity about 

 2. When placed in the fire, it 

 blazes, crackles, and gives out a 

 black smoke and bituminous odour, 

 and is converted into a whitish or 

 reddish ash: it sometimes effer- 

 vesces slowly with acids. 

 BITUMINOUS SPRINGS. We are in- 

 formed by Sir C. Lyell that springs 

 impregnated with petroleum, and 

 the various minerals allied to it, 

 are very numerous, and are, in 

 many cases, undoubtedly connected 

 with subterranean fires. The most 

 powerful yet known, are those on 

 the Irawadi, in the Burman empire, 

 which, from one locality, are said 

 to yield 400,000 hogsheads of pe- 

 troleum annually. 



BLACK CHALK, (the Zeichen scheifer 

 of Werner ; argile schisteuse gra- 

 phique of Haiiy ; ampelite gra- 

 phite of Brogniart; le schiste a 

 dessiner of Brochant.) A clay of 

 a bluish black colour, extremely 

 soft, a quality which it owes to the 

 presence of about twelve per 

 cent, of carbon. That most 

 esteemed is found in Italy and 

 Germany, and takes its name 

 from those countries respectively. 

 It is massive, opaque, soils lightly, 

 and writes ; retains its colour in 

 the streak, and becomes glistening ; 

 is soft, sectile, does not adhere to 

 the tongue, feels fine, but meagre, 

 and is infusible. According to 

 Wiegleb, a variety from Bayreuth 

 contained silica 64 '50, alumina 



