WIT 



[463] 



WOO 



also to petioles having a leafy 

 border on each side. 



WI'THAMITE. A mineral, so named 

 by Sir 1). Brewster, in honour of 

 its discoverer, H. Witham, Esq. 

 It occurs at Gleneo, in Argyleshire, 

 in minute translucent, brilliant 

 carmine red crystals, in form re- 

 sembling epidote. Specific gravity 

 = 3-1-3-3. Hardness == 6-0-6-5. 

 Allan. 



WI'THERITE. So named after Dr. 

 Withering, its discoverer. Carbo- 

 nate of Barytes. The Baryte car- 

 bonatee of Haiiy ; the Witherit of 

 Werner; the Barolite of Kirwan. 

 Witherite, or native carbonate of 

 barytes, is one of the rarer produc- 

 tions of the mineral kingdom. At 

 Anglesark, in the county of Lan- 

 caster, it is found in veins travers- 

 ing the independent coal formation, 

 and accompanied by blende, galena, 

 calamine, and heavy spar. It 

 occurs also in Shropshire, in the 

 lead mines, where it is met with 

 in irregular masses, weighing from 

 forty pounds to two or three hun- 

 dred weight, imbedded in heavy 

 spar. The name given to this sub- 

 stance by the miners is yellow spar, 

 not that this is its real colour by 

 day-light, but its transparency is 

 so considerable that if a lighted 

 candle be placed behind a mass of 

 it, the whole will glow with a yel- 

 lowish light, a circumstance by 

 which the miners distinguish it 

 from heavy spar. The colour of 

 witherite is white with the slightest 

 possible, if any, tinge of yellow; 

 its fracture is broad striated, ap- 

 proaching to straight foliated ; it is 

 for the most part massive. The 

 Anglesark witherite, according to 

 Klaproth, contains, besides carbo- 

 nate of Barytes, above two per 

 cent, of carbonate of strontites, and 

 a scarcely appreciable quantity of 

 oxide of copper. A specimen 

 analyzed by Mr. Aiken, gave, car- 

 bonate of barytes 96-3, carbonate 



of strontites 1*1, sulphate of barytes 

 0'9, silex 0*5, alumine and oxide 

 of iron 0'25. 



WOLF. (wolf, Germ.) The wolf 

 affords an excellent illustration of 

 the complete extinction of species. 

 Wolves were formerly exceedingly 

 numerous in Great Britain, and 

 were met with in Ireland even so 

 late as the beginning of the 18th 

 century. At the present day, 

 unless seen in a menagerie, or read 

 of as still existing in other count- 

 ries, and formerly in this, the 

 natives of these islands might be 

 perfectly unaware that the wolf 

 ever had any existence. 



WO'LFEAM. The name given by 

 Werner to the ferruginous oxide of 

 tungsten. 



WO'LLASTONITE. A mineral, thus 

 named in honour of Dr. Wollaston. 

 Prismatic augite. 



WOOD-COAL. Another name for brown 

 coal. 



WOOD-OPAL. Opalized wood. The 

 Holz-opal of Werner ; the Quartz 

 re*sinite xylo'ide of Haiiy : Ligni- 

 form opal of Kirwan. A variety 

 of opal, occurring in various vege- 

 table forms, and being in reality 

 opalized vegetable matter. Wood 

 changed by silicious infiltration, in 

 which the original structure is still 

 preserved, often in its minutest 

 parts, and the woody fibres appear 

 rather masked by its silicious in- 

 vestment than destroyed. Wood 

 opal is of various colours, white, 

 grey, brown, and black. In frac- 

 ture, lustre, and translucency, it 

 scarcely differs from semi-opal ; it 

 may be regarded as intermediate 

 between common opal and semi- 

 opal. Prof. Jameson relates that 

 many years ago, the trunk of a tree 

 penetrated with opal was found in 

 Hungary, which was so heavy that 

 eight oxen were required to draw 

 it. It is found in Hungary, the 

 Faroe Islands, and Van Diemen's 

 Land. 



