[ 3 11 3 
fiduum gives feme Particles of Salt together with 
feme ftony and mineral ones. 
I have found by Experience, that petrifying Springs 
are generally impregnated, feme with calcarious and 
Particles of other Stones, and others with fermgine- 
ous and vitriolic Particles. Thofe of the ftony or 
calcarious Kind, I have obferved, when they drop on 
Wood, or other Vegetables, aft on them for the moft 
part by Incruftation, having different Degrees and 
Periods for their refpeftive Xftcruftations and Co- 
alitions, which yet flick clofe to one another : They 
feldom turn the Wood into Stone 5 but, flicking to 
the Wood, Plants, &c. coagulate on it, and by 
degrees cOver it \Vith a Cruft of a whitifh Subftance 
of different Thicknefs, whereby the Wood is ini- 
merged or wrapped in a ftony Coat, which, if it be 
broken before the Wood be rotten, you will find it 
in the Heart of the Stone or Incruftation, as is feen 
in thole Petrifications at Maudlin Meadows in Glou~ 
cejlerjhire , at Hermitage near 'Dublin , and many 
other Places ^ Or, if the Wood be rotten, you will 
find a Cavity in the Stone, which very often is filled 
by a fubfequent Incruftation or Petrification 5 the 
ftony Particles then taking the Place of the rotten 
Wood. 
Sometimes indeed, thefe Waters, permeating the 
Pores of the Wood either longitudinally or tranf- 
verfely, infinuate themfelves therein, fill them, up 
with their ftony Particles;, fwell, and, by their burn- 
ing or corroding Qiiality proceeding from the 
Lime-Stone, deftroy the Wood, and affume the Shape 
of the Plant', the Place whereof they have taken. 
Rr ' Thefe 
