347 



pitch-stones, and fossil wood, is rendered still more probable, and 

 even certain, by the chemical properties they exibit 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 OP OPALINE WOOD*, 



Of a splintery fracture gives fire with steel a fine polish of a brownish 



yellow colour. 



o 



= 



'A portion digested with alcohol, at ebullition, yielded no precipitate, 

 nor cloudiness, on mixture with water. 



8 S Pulverized, and digested, with concentrated sulphuric acid, nearly boil- 

 ing, blackened the acid slightly. 



i Projected, with nitre, into a red-hot silver crucible, produced no defla- 

 * I gration, nor appearance of carbonaceous matter. 



Digested with the acids sulphuric, nitric, and muriatic- it produced 

 no change, except, as before noticed, with the concentrated sul- 

 phuric. 



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. 



c 

 o 



I 



"o 



CO 



