I 317 ] 
'Mineral Steams or Exhalations, being highly fatu- 
rated with ftony and mineral Particles, are often 
found to have a petrifying Virtue, as is feen at the 
Bath called Green ‘Pillars (a) in the City of Buda 
in Hungary . If fuch Steams fhould, in certain Places, 
find or force their Way thro a the Sand or Pores of 
the Earth, they may operate on Wood, &c. buried 
in the Ground, permeate its Veffels, and, by degrees, 
turn it into Stone ; and fuch, I apprehend is the 
mod probable, if not the only Reafon, that can be 
afiigned for thofe Petrifications of Wood found in 
Sand, as mentioned by Boyle and Plot. 
It may be obfcrved, that the finer the lapidific Par- 
ticles are, the more beautiful and natural the Petri- 
fication will appear ; fuch is a petrified Root of the 
Flag or Iris fylveftris in my Poffefilon, which is fo- 
lid Stone at the Bottom, the Pith being turned into 
a white or (parry Subftance, and the growing Knots 
of the Root, tho' petrified, preferving their Skin 
brown, and fomewhat flexible. This Phenomenon 
indeed has been lately folved in the Defcription of 
the County of c Do t wn , p . 162. The Lufus Na- 
ture, or Sportings of Nature, is a general Solu- 
tion, too often brought in, and comes in very 
a propos to anfwer Queries concerning Petrifications, 
fuch as Wood, Shells, Worms, &c . If the Shells, 
or other like petrified Bodies (found in Marble or 
Lime-Stone) which preferve the mod exaft Refem- 
blance of the Fifh or Body they reprefenr, were not 
formerly a real Fifh, Shell, Worm, &c. how comes 
it 
(a) PhiloJ. Tranf, N®, 59. p, 104.9. 
