121 



TAB. CLXIII. 



S I L E X quartzum ; var. ligniformis. 

 Wood-like Quartz, or Petrified Wood. 



Class 2. Earths. Order!. Homogeneous. 

 Gen. 4. Silex. Spec. 1. Quartzum. 



Div. 2. Imitative. 



Petrified Wood is by no means uncommon. It is, 

 however, equally curious with many rarities, in showing 

 some of the phaenomena of the creation. Thus we find, 

 when one substance passes away, another takes its place. 

 This is an excellent evidence that when one substance passes 

 to decay it forms and organizes others. The water that 

 once assisted in the rise and flourishing verdure of the 

 wood when in youth and health, now, in decay, helps to 

 introduce a new substance in its place, and with such 

 nicety that it is quite a deception. The colour and ex- 

 ternal appearance are still the same, although turned to 

 stone; and the parts of the Wood, Hydrogen and Car- 

 bonic Acid are now evaporated. 



This specimen was brought from Fonthill in Wiltshire 

 by A. B. Lambert, Esq., V. P. L. S. It was eighteen 

 inches in length, and twelve inches in circumference, and 

 is one of the best specimens I have seen to show the nature 

 of the change of place, viz. the Silex replacing the carbo- 

 naceous principle of the wood ; the Silex in solution, as it 

 were, taking place of the former substance particle by par- 

 ticle. It is admirable to see the longitudinal and lateral fibres 



