[ 3^3 ] 
deal of faline Particles, whofe Sides being ftronglj 
attra&ed to each other, and clofely joined, hinders 
the Fire from expanding the Pores of thefe Stones, 
and their being reduced to Lime. 
This black Stone, when broken, appears thro’ the , 
Microfcope very beautiful, and like Cloth of Silver, 
the Pores and Veflels of the Wood being filled with 
white minute Cryftals. 
Of thefe Stones I have fome with Wood out- 
wardly continuous s others with Wood inwardly ; 
one, the leaft Part whereof is Stone, the reft Wood 5 
another vice verja s another intirely Wood, except a 
thin Coat of Stoneon one Side, which appears to be the 
very Bark ; one Stone which at one End diftindly Chews 
the annual Ringlets of the Wood ; one that fhews 
the Wood, before it was petrified, had been bent, 
and partly broken, the Fiffure being filled with a 
fparry Matter, and appears plainly from the prefent 
Appearance and Pofition of the Fibres of the Stone. 
Some of thefe Stones ftrike Fire with a Steel, and 
others, by a ftrong Collifion, emit a Train of Sparks. 
Some of thefe Stones fhew the Grain of Holly, 
Afh, and Fir. I have but one Piece of Oak petri- 
fied, eafily diftinguifhed by its Grain 5 it fhews the 
very Knots of the Wood where young Twigs were 
cur } and has a Hole made thro’ it before it was pe- 
trified. 
As for thefe Stones being fit for fharpening or fet- 
ting of Razors, &c: the black ones are rather too 
hard, and the white ones too fofr. The Whetftones 
or Hones, vulgarly fo called, which are fold for 
Lough-Neagh Stones, are none of thefe, but of a 
foft gritty kind, and found near Drogheda. 
When 
