B V 



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BO'BON. The undecomposable base of 

 boracic acid ; this may be obtained 

 by heating in a copper tube two 

 parts of potassium with one of 

 boracic acid previously powdered 

 and fused. Boron is a dark olive 

 coloured substance, having neither 

 taste nor odour, insoluble in water, 

 and a non-conductor of electricity. 

 It is about twice the weight of 

 water. Its symbol is B. 



Boss, (bosse, Fr.) A protuberance 

 or swelling ; a kind of knob or stud. 



BOSSED. Knobbed or studded. 



BOTHBTOLE'PIS. The name assigned 

 to a genus of ichthyolites of the 

 Old Red Sandstone, and described 

 by Agassiz in his Poissons Fossiles. 



BOTHBODE'NDEON. (from fioOpos and 

 SevSpov, Gr.) An extinct genus of 

 coniferge belonging to the coal for- 

 mation. The bothrodendron has a 

 stem not furrowed, covered with 

 dots. Scars of cones, obliquely 

 oval. The stems are marked with 

 deep oval or circular concavities, 

 which appear to have been made 

 up by the bases of large cones. 

 These cavities are ranged in two 

 vertical rows, on opposite sides of 

 the rock, and in some species are 

 nearly five inches in diameter. 

 Prof. BucUand. 



BO'TBYOID. | (from fiorpvs, a bunch 



BOTBYOI'DAL. ) of grapes, and e/os, 

 form.) Resembling a bunch of 

 grapes ; clustered like grapes. 



BOTBY'OLITE. (from fiorpvs, a cluster 

 of grapes, and \i'0o<?, Gr.) " A 

 mineral presenting an aggregation 

 of large sections of numerous small 

 globes is termed lotryoidal ; but 

 when the globes are larger, and the 

 portions are less and separate, the 

 appearance is expressed by the 

 termmammillated." Phillips. Grape 

 stone ; a variety of prismatic dato- 

 lite, occurring in mammillary con- 

 cretions. 



BO'VEY COAL. A name given to wood- 

 coal, from its having been found in 

 abundance at Bovey Heathfield 



B V 



near Exeter; called also brown- 

 coal. In wood-coal we may almost 

 seize nature in the act of making 

 coal, before the process is completed. 

 These formations of coal are far 

 more recent than those of common 

 coal, and have been referred to the 

 first, or Eocene, period of the 

 tertiary formations. Heat and 

 pressure appear to be required to 

 convert wood coal into mineral 

 coal. Bovey-coal contains carbon 

 77*19, oxygen 19*34, hydrogen 

 2 '54, earthy parts 1. 



" The precise age of the Bovey 

 coal," says Sir H. de la Beche, 

 " cannot at present be well deter- 

 mined. A body of water has 

 passed over it, working hollows in 

 the clay, and leaving a large 

 deposit of transported substances in 

 some situations. It also appears 

 to have been tranquilly deposited 

 in a previously existing depression. 

 The area comprising the surface of 

 this deposit is far more extensive 

 than is usually given, and it has 

 certainly once occupied a greater 

 elevation, as a mass, than it now 

 does, the upper portion having 

 been removed by denudation. The 

 principal deposit of lignite occurs 

 near Bovey Tracy, in Devonshire, 

 at the north-western end of the 

 deposit. Beneath about twenty 

 feet of what the workmen term 

 the head, there is an alternation of 

 compressed lignites; shales or clays. 

 The lignite is composed of dicoty- 

 ledonous trees, many of which are 

 knotted. The most useful product 

 of this deposit is a clay used in the 

 potteries, in some cases so fine as 

 to constitute what is termed pipe- 

 clay. Lignite more or less ac- 

 companies the clay throughout, 

 occurring either in beds or in small 

 detached pieces. Animal remains 

 must be rare ; for I could not, after 

 diligent search, obtain any traces 

 of them, though I was told some 

 shells had been seen at Teignbridge. 



