349 
DEAR SIR, 
CoNCEiviNO that a portion of the opaline wood being mixed 
with twice its weight of purified nitre, and exposed to heat, if carbon was present 
in the stone, it would unite with the oxygen of the nitre, and produce carbonic 
acid gas, I proceeded to the following experiment. 
Into a coated glass retort, with a conducting tube entering a bottle of lime- 
water, 50 grains of fossil wood, and 100 of nitre of pot-ash, were introduced ; and 
it was then surrounded with heated charcoal. After the expansion of the atmos- 
pheric air, an absorption took place, from the fusion of the nitre; this was 
guarded against, by lifting the conducting tube from the water; as soon as gas 
was liberated, it was again immersed, and a copious precipitation, and cloudiness 
of the lime-water, ensued. This continued for some minutes ; it was then suc- 
ceeded by the liberation of oxygen gas, with nitrous gas, occasioning no precipi- 
tation in fresh lime-water. In 36 minutes the retort was perfectly white hot, 
and slight absorption began to take place: the retort was then removed, and when 
cool was broken: the mass was found strongly agglutinated, possessing a tinge 
of pink. 
I am, with sincere respect, yours, 
W. H. PEPYS, jun. 
The presence of carbon having been thus proved, my next eager 
wish was to endeavour to discover the nature of this substance, which 
thus contained carbon as a principle ; entertaining an expectation, 
that some evidence would appear, that it was vegetable matter, 
which had undergone the bituminizating process, or fermentation : I 
therefore requested Mr. Pepys, without mentioning my conjecture, 
to submit a portion of similar fossil wood, with that which had been 
employed in the foregoing experiments, to simple distillation, over a 
naked fire. This request was kindly complied with, and the result 
appears in the following letter. 
SIR, 
Agreeable to promise, I have made the experiment you requested. 
250 grains of the opaline wood were pulverized, and placed in a coated glass 
retort; to which a tubulated receiver, with a conducting pipe, leading into a bottle 
of lime-water, was luted. Gradual heat being given, rarefied the atmospheric air 
