SOO Mr. Witham's Description of a Fossil Tree. 



partly volatile, yielding inflammable gas and bituminous matter by heat. 

 The residue is nearly pure charcoal = nearly 14.3 p. c. The mi- 

 neral contains very minute traces of Silica and Alumina. The other 

 fragments have a similar composition, only the Lime is more abundant 

 from the presence of some crystals of Limestone which it is impossible 

 to separate completely." 



Analysis of Fossils found in Berwickshire. 



Carbonate of Lime, 78.26 



Peroxide of Iron, 16.50 



Protoxide of Iron, 3.40 



Loss, L95 



100.00 



All these were found in the Mountain Limestone groups. In different 

 parts of the tree we will come to somewhat different results respecting 

 the proportions of the abovenamed substances. 



The following is the analysis of the vegetable Fossils found in the 

 Coal-field, or, in other words, lying between the Encrinal or Mountain 

 Limestone, and the new Red Sandstone deposits. 



Fossil found in a quarry at Heworth Shore, near Newcastle. 



Silica, 95 per ct. 



Peroxide of Iron and Alumine, 5 



100 



The following remarks were kindly transmitted to me by Mr. 

 James Johnston, of Portobello, upon the Wideopen Fossil, and that at 

 High Heworth, near Newcastle. 



" The fragments of the two Fossils transmitted to me have the same 

 external characters. Both are of a dark brown, from the presence of 

 peroxide of Iron in a very insoluble state. About one-half of the mass 

 of both consists of Silica in a crystalHzed state (common Quartz crys- 

 tals), presenting in the cavities beautiful groups of crystals of the com- 

 mon form. The cavities in the High Heworth tree are more frequent 

 and regular, forming parallel fissures, separated by thin walls of a more 

 compact body, running in the direction of the fibres of the original 



