350 
in the vessels, which passed through the lime-water; in 15 minutes this ceased, 
and the retort being red hot, a small quantity of water dropped from the beak into 
the receiver; and, as it there collected, an oily, or sublimated film, appeared on its 
surface. The strongest heat of this furnace was continued about an hour; when 
evident absorption taking place, and the distillati ^n ceasing, the operation was stopped. 
Upon 0 ])ening the receiver, a strong einpyreumatic smell was observed. The liquor 
obtained has a dull yellow colour, with small scales on its surface, and in quantity 
about 20 drops; the greatest part of the scaly substance adhered to the receiver on 
pouring out the fluid. The substance in the retort was still pulverulent, but much 
more white than when introduced. The liquid shows no acid properties, by the 
test of litmus paper, or violets. 
I am, with much respect, 
W. H. PEPYS, jun. 
The oihj, or sublimated film, and the strong empyreumatic smell, 
afford some reason for believing in the presence of bitumen in this 
opaline wood ; but anxious only for the discovery, and communi- 
cation, of the truth, I wish you to suspend your opinion, until your 
judgment has been aided by other corresponding experiments, which 
I shall now adduce. 
Common pitch-stone, that which displays no obvious trace of 
wood, hals-opal of Emmerling, and from its resinous or pitchy 
lustre, the pierre de colophane of De Lisle, and the pierre de poioc of 
Daubenton, differs in no respect from the former kind, except in 
the absence of those marks which give to that a resemblance to 
wood. Believing this to depend merely on the bituminous wood, 
which enters into the composition of this latter substance, having 
become so fluid as to have had the remains of its fibrous structure 
quite melted down, whilst in the former some of the fibrous struc- 
ture remains, I conceive it not entitled to be considered as of a dif- 
ferent family from the former, as has been done by the celebrated 
Mr. Kirwan, and other mineralogists. In proof of this opinion, we 
often see, in the same specimen, in one part, distinct fibrous appear- 
ances ; in another part of the same substance, the fibrous appear- 
