curious manner, mentioning the sulphur and nitre, but conceals the
charcoal in an anagram. The words are, sed tamen salis petrae _lure mope
can ubre_, et sulphuris; et sic facies tonitrum, et corruscationem, si
scias, artificium. The words lure mope can ubre are an anagram of
carbonum pulvere. Biograph. Britan. Vol. I. Bacon de Secretis Operibus,
Cap. XI. He adds, that he thinks by an artifice of this kind Gideon
defeated the Midianites with only three hundred men. Judges, Chap. VII.
Chamb. Dict. art. Gunpowder. As Bacon does not claim this as his own
invention, it is thought by many to have been of much more antient
discovery.

The permanently elastic fluid generated in the firing of gunpowder is
calculated by Mr. Robins to be about 244 if the bulk of the powder be 1.
And that the heat generated at the time of the explosion occasions the
rarefied air thus produced to occupy about 1000 times the space of the
gunpowder. This pressure may therefore be called equal to 1000
atmospheres or six tons upon a square inch. As the suddenness of this
explosion must contribute much to its power, it would seem that the
chamber of powder, to produce its greatest effect, should be lighted in
the centre of it; which I believe is not attended to in the manufacture
of muskets or pistols.

From the cheapness with which a very powerful gunpowder is likely soon
to be manufactured from aerated marine acid, or from a new method of
forming nitrous acid by means of mangonese or other calciform ores, it
may probably in time be applied to move machinery, and supersede the use
of steam.

There is a bitter invective in Don Quixot against the inventors of gun-
powder, as it levels the strong with the weak, the knight cased in steel