MicrocRarHras’ 107 
“Obferv. XVII. Of Petcify'd wood, and otber Petvify'd bodiess 
Bie She S| 
F this fort of fubftance, I obferv’d:feveral pieces of very differing 
kinds, both fortheir outward fhape, colour, grain, texture, hard- 
nels, &c. {ome being brown and redifhs otheis gray, like a Hone 3others 
black, and Flint-like : fome foft,likea Slate or Whetftote, others as hard 
as aFlint, and as brittle:: That which I-more particular examin'd,was a 
piece about the bignefs of a mans hand, which feem’dto have beena part 
of fome large tree, that by rottenne/s had been broken off from it before 
it began tobe petrify'd. fal) Sail nibre y over: 
And indeed, all that Ihave yet feen, feem tohave been rotten Wood: 
before the petrifaction was begun;.and not long fince, examining and 
viewing a huge great Ozk, that feem'd with meer age to be rotten as it 
ftood, I was very much confirm’d in this opinion; for I found, that the 
grain, colour, and fhape of the Wood, was exactly like this petrify'd fub- 
{tance 5 and with a Afcrofcope, ¥ found, that all thofe Aficrofcopical pores, 
which in fappy or firm and found Wood are fill'd with the natural orin- 
Mate juices of thofe Vegetables, in this they were all empty, like thofe 
of Vegetables charr'd 5, but with this difference, that:they feem’d much 
larger then I have feen any in Char-coals 3 nay, even then thofe of, Goals 
made of great blocks of Timber, which:are commonily call’d O/d-coals. 
- The reafon of which difference may probably be, that the charring of 
Vegetables, being an operation quickly perform d,and whileft the Wood 
Is lappy, the more folid arts may more edfily thrink together, and con» 
traét the pores or inter/titia between them, then in the rotten Wood, 
where that natural juice feems onely to be wath’d away by adventitious 
or unnatural moifture; and fo though the natural. juice be wafted from 
between the firm parts, yet thofe parts, are kept afunder by the adventi~ 
#0us moyftires, and fo by degrees fettled in thofe poftures:) 
_ And this I likewife found in the petrify'd Wood; that the pores were 
fomewat bigger then thofe of Charcoal, each pore being neer upon half 
as bigg again, but they did not bear that difproportion which is: expreft 
in the tenth Scheme; between the: fmall fpecks or pores in the frit Fis 
ate refenteth the pores of Coal or Wood charr'd) and the 
black fpots of the fecond F igure (which reprefent the like Adicrofcopical 
bores inthe petrify d Wood) for thefe laft were drawn by a Adcrofeope that 
3 Sta ‘d the object above fix times = econo then the Aficre- 
be Dy which thofe pores of Coal were oblervids oi Pn DCoW 
_. Now, mete tena a little bigger, yet did they keep the exact 
Figureand or er of the pores of Coals and of rotten Wood, which Jaft 
aulO'were much of the {ame-dizel 1299478 71 S10lod enol 1: cow TOmgSHO ” 
The other Obfervations.on this petrifjid fabftance, that a whilé fince, 
by the appointment of the Rayal Society, 1 made, and. prefented to them 
‘naccount of; were thefe that follow; aa had the honour done t by 
eed) 2 
