248 Count Rumford's Experiments to determine 
moment of the explosion in the form of an elastic fluid, was 
now found transformed into a solid body as hard as a stone ! 
It may easily be imagined how much this unexpected appear- 
ance excited my curiosity ; but, intent on the prosecution of 
the main design of these experiments, the ascertaining the 
force of fired gunpowder, I was determined not to permit my- 
self to be enticed away from it by any extraordinary or unex- 
pected appearances, or accidental discoveries, however alluring 
they might be ; and faithful to this resolution, I postponed the 
examination of this curious phaenomenon to a future period ; 
and since that time I have not found leisure to engage in it. 
I think it right, however, to mention in this place such cursory 
observations as I was able, in the midst of my other pursuits, 
to make upon this subject ; and it will afford me sincere plea- 
sure, if what I have to offer should so far excite the curiosity 
of philosophers, as to induce some one who has leisure, and 
the means of pursuing such inquiries with effect, to precede me 
in the investigation of this interesting phaenomenon ; and as 
the subject is certainly not only extremely curious in jtself, but 
bids fair to lead to other and very important discoveries, I 
cannot help flattering myself that some attention will be paid 
to it. I have said that the solid substance into which the 
elastic vapour generated in the combustion of gunpowder was 
transformed, was as hard as a stone. This I am sensible is 
but a vague expression ; but the fact is, that it was very hard, 
and so firmly attached to the inside of the barrel, and parti- 
cularly to the inside of the upper part of the vent tube, that it 
was always necessary, in order to remove it, to make use of a 
drill, and frequently to apply a considerable degree of force. 
This substance,, which was of a black colour, or rather of a 
