390 
guished by the epithe't metallic. A specimen of fossil wood, which 
I have lately obtained, yields a beautiful instance of this sub- 
impregnation with copper. The ligneous form and texture, with 
even the knots, are perfect. The colour in some parts diifers but 
very little from that of decayed wood, whilst the central part demon- 
strates the strongest marks of its having undergone the bituminous 
fermentation; and the surface, tinged, more or less, of a greenish 
hue, is marked by a few spots of malachite : the whole demonstrating 
that an impregnation, with a solution of carbonate of copper, had 
taken place, and had arrested the progress of the bituminizating 
process. 
The combination of the other metals with fossil wood is not very 
frequent. Some authors, and particularly Volkman, have spoken 
of wood impregnated with silver. That this may have been the 
case is by no means improbable ; at the same time, it is not to be 
positively concluded, that the specimens, of which they speak, were 
impregnated with this metal ; since it is not said that they had been 
submitted to any chemical test ; and the brilliance of some pyrites 
is such, that, although they do not contain the least particle of 
silver, they frequently exhibit the splendour, and the whiteness of 
that metal. 
The respectable author of Outlines of an Attempt to establish a 
Knowledge of extraneous Fossils on scientific Principles, and of 
Petrficata Derhiensia, informs us in the former of these works, p. 
150, that he has seen specimens of fossil wood, thoroughly impreg- 
nated with lead, or rather galena. A specimen is now before me, 
from Lord Bute’s Museum, which is evidently thus impregnated. 
Yours, &c. 
