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WOOD-STONE. The Holstein of Wer- 

 ner ; Quartz agathe xylo'ide of 

 Haiiy ; Le bois petrifi e of Brochant. 

 Wood petrified with hornstone. 

 Prof. Jameson places wood- stone as 

 a subspecies of hornstone ; Prof. 

 Cleaveland terms it agatized wood, 

 and says this substance appears to 

 have been produced by the process, 

 commonly called the petrifaction 

 of wood. It is essentially composed 

 of silicious earth, which, it is 

 highly probable, has been gradually 

 deposited, as the vegetable matter 

 was decomposed and removed. 

 Both its form and texture indicate 

 its origin. Thus it presents, more 

 or less distinctly, the form of the 

 trunk, branches, roots, or knots, 

 which once belonged to the vege- 

 table. The colour of wood-stone 

 is generally grey, shaded with blue, 

 yellow, &c. The colours are often 

 with spots, sometimes striped. 

 Hardness nearly that of common 

 quartz. Specific gravity 2*67. It oc- 

 curs in sandstone or sandy loam, and 

 is capable of being highly polished. 



WOOD-TIN. The Etain oxide concre- 



tione* of Haiiy. The Kornishches 

 Zinnerz of Werner. A variety of 

 oxide of tin ; fibrous oxide of tin. 

 This has been hitherto found only 

 in Cornwall and Mexico. It occurs 

 in fragments which are generally 

 rounded. Its colours are light or 

 chesnut brown, reddish brown, and 

 yellowish grey. It is opaque ; of 

 a fibrous texture; easily broken. 

 Specific gravity from 6'4 to 6*7. 

 It is infusible before the blowpipe, 

 and irreducible. It consists of 

 oxide of tin 91 '0, oxide of iron 9. 



WORTH SANDSTONE. So named from 

 its being fully developed at Worth, 

 near Crawley, in Sussex. A series 

 of white and yellow sands, consti- 

 tuting the lowermost member of 

 the Hastings beds. Its organic 

 remains are principally ferns and 

 arundinaceous plants. 



WOE'THITE. The name assigned to 

 an earthy mineral, occurring in 

 boulders in Sweden, and Finland. 

 It is met with in foliated crystal- 

 line masses of a white colour; 

 transparent ; lustre vitreous ; 

 scratches quartz. Allan. 



X 



XA'NTHITE. An earthy mineral, con- 

 sisting of a congeries of small 

 rounded grains, easily separable 

 and may be crushed by the nail. 

 Colour greyish or yellow. It has 

 been found only at Amity, in 

 Orange County, United States. 



XI'PHIAS. (Wia?, from /0o9, a 

 sword, Gr.) The sword-fish. 



XI'PHODON. (Sword- tooth.) The name 

 assigned by Cuvier to a sub-genus 

 of Anoplotheria. In the xiphodon 

 the anterior molars are slender and 

 trenchant, and the posterior ones 

 below have, opposite the concavity 

 of each of their crescents, a point 



which, in the course of wear, also 

 takes the form of a crescent, so that 

 then the crescents are double, as in 

 the ruminants. Pidgeon. The 

 xiphodon has been hitherto found 

 fossil only, and in post-cretaceous 

 strata. It is a small and delicate, 

 long and slender limbed anoplo- 

 therian animal. A second species, 

 Xiphodon Geylensis, has been 

 added by M. Gervais to the type 

 species, Xiphodon Gracilis. The 

 existence of the Xiphodon is con- 

 sidered to have been limited to the 

 Eocene period. 

 XI'PHOID. (from |f/0o9 ; a sword, and 



