347 
pitch-stones, and fossil wood, is rendered still more probable, and 
even certain, by the chemical properties they exhibit when subjected 
to the action of fire, and of other appropriate re-agents. 120 grains 
of opaline wood, from the specimen at Plate II. Fig. 4 and 5, were 
reduced to a coarse powder, and digested without heat, for two 
months, with 180 grains of pure pot-ash, and half an ounce in mea- 
sure of water, when the whole of the silicious matter became nearly 
dissolved, forming a thick liquor silicum ; whilst the sediment which 
remained was considerably darkened, and became exceedingly light 
and flocculent ; bearing the appearance of carbonaceous matter. 
But to render the knowledge of the constitution of opaline wood 
quite perfect, I again had recourse to the abilities of Mr. Pepys ; 
whose excellent report I here subjoin. 
SPECIMEN OF OPALINE WOOD*. 
Of a splintery fracture— gives fire with steel — a fine polish — of a brownish 
yellow colour. 
o . 
5 ■*-> 
O 
o) d 
O ^ 
cd 
5 ^ 
2 ^ 
-P o 
^ 0) 
tL, 
A portion digested with alcohol, at ebullition, yielded no precipitate, nor 
cloudiness, on mixture with water. 
Pulverized, and digested, with concentrated sulphuric acid, nearly boiling, 
blackened the acid slightly. 
Prcyected, with nitre, into a red-hot silver crucible, produced no deflagration, 
nor appearance of carbonaceous matter. 
a 
o 
o 
1/3 
O 
Digested with the acids — sulphuric, nitric, and muriatic— it produced no 
change, except as before noticed, with the concentrated sulphuric. 
Heated with caustic pot-ash, in a silver crucible, it dissolved, and ran per 
deliquium, on exposure to the atmosphere. 
* 
Plate II. Fig. 4 and 5. 
