2 3 8 C H E M I 
however, always retains a fmall quantity of fulphur, 
fince, according to the obfervation of that chemift, it 
emits a fulphureous l'mell till it is entirely reduced to 
allies. He elfimates the fulphur, retained by the char¬ 
coal, at one twenty-fourth of its weight. Gun-powder 
may likewife be deprived of its fulphur, by expofing it 
entire, and without previous walking, to the aftion of a 
gentle heat, as Mr. Robins, in his Treatife on Gunnery, 
has well obferved. The perfons who fteal game have 
been long in the habit of defulphurating gun-powder, 
by expofing it in a tin dilh to the heat of a bed of allies. 
They are perfuaded, that the powder in this ftate, im¬ 
pels the fhot to a much greater diftance, and does not 
foil the piece fo much. 
Chemifts and natural philofophers have maintained 
various opinions refpefting the violent effects of gun¬ 
powder; feme have attributed them to water, reduced 
into vapour, and others to the fudden dilatation of air. 
Baume fuppofed them to a rife from a nitrous fulphur, 
formed in the inltant of combuftion. Fourcroy thinks 
this phenomenon may be very readily explained, by the 
application of the modern improvements in chemillry. 
He obferves, that all the phenomena, which attend the 
inflammation of gun-powder, depend entirely on its 
great combullibility. Sulphur and carbon, minutely di¬ 
vided, are bodies highly inflammable. The intimate 
mixture, which has fo great an influence on the force of 
gun-powder, as Baume’s valuable experiments have 
fihown, is the only caufe of its effefts. The nitre is ■ 
equally Jifperfed among all the particles of very com- 
bullible matter: as its quantity is much the greateft, each 
particle of fulphur and charcoal is furrounded, and, as 
it were, covered with nitre. A much greater quantity 
of vital air, than is neceftary for the complete ccmbuf- 
tion, will be produced; it being well afeertained, that 
nitre affords that fluid in great quantities, by the appli¬ 
cation of heat. The fame thing happens in this com- 
huflion, as. is obferved, when a combuftihle body is 
plunged- in a veffel filled with vital air; that is to fay, it 
is burned with great vivacity, and in much lets time 
than in the common atmofpheric air. It follows, there¬ 
fore, that the fulphur and the charcoal muft be burned 
in an infiant, becaufe they are really plunged in an at- 
mofphere of vital air. Hence, fays Fourcroy, the rapid 
inflammation of powder, its taking place in clofe veffels, 
and the terrible force with which it explodes and drives, 
every obftacle before it, may be eafily conceived. But 
this explanation, as given.hy. Fourcroy, of the explofive, 
effefts of gun-powder is rendered extremely doubtful by 
the late ingenious and difficult experiments which count 
Rumford has made upon this fubjeft, of which a very 
minute account is to be found in the volume of the Pby-. 
lofophical Tranfactions for 1797. By contriving to tire 
gun-powder in an apparatus, in which the elaftic fluid 
generated was made to aft with a determined force 
dgainft a weight capable of being increafed or diminifhed 
at pleafure, the count was enabled to calculate the force 
which this fluid exerts with a very tolerable degree of 
accuracy. In fome experiments this force amounted to 
no lefs than 412529 lbs. a force 55004 times greater than 
the mean preffure of the atmofphere. When the weight 
was increafed fo as to confine the elaftic fluid for a few 
minutes after the inflammation of the powder, it was 
found to poflefs only a very fmall degree of expanfive 
force ; for, on railing the weight, the fluid ruflied out 
with a noife hardly fo loud or iliarp as the common re¬ 
port of an air-gun. It became obvious from this and fi- 
milar experiments, that the quantity and force of the 
permanently elaftic fluid generated were by no means 
adequate to explain the phenomena. Count Rumford 
was therefore led to fearch for the caufe of thefe pheno¬ 
mena in the temporary aftion of a fluid not perma¬ 
nently elaftic; and this fluid lie conceived to be water, 
whichhadBeen converted into vapour by the caloric evol¬ 
ved during the combuftion of the inflammable materials 
a 
S T R Y. 
of which gun-powder is compofed. Two conditions only 
feemed to be required to render this fuppofttion proba¬ 
ble ; ill, The exiltence of a lufticient quantity of water 
in gun-powder; and, fecondly, The evolution of a 
quantity of caloric not only fufiicient to Convert this wa¬ 
ter into fleam, butalfo.to raife its temperature in that 
ftate to a very confiderable degree. 
The firft condition is found in the quantity of water 
aftually contained in gunpowder, which from experiment 
appears to amount to fifteen grains of this fluid in every 
cubic inch of thepowder. Tiiefecond condition is to be 
fought for in the aftual degree of heat, which is excited 
during the inflammation of gunpowder, and the eftefts 
which this degree is known to have of increaling the ex¬ 
panfive force of aqueous vapour. With regard to the 
degree of heat, it may be remarked, that brafs lias been 
known to melt in the heat generated during thecombuf- 
tion of gunpowder, when-this metal was previoufly re¬ 
duced to very fmall particles, and mixed with if. Now, 
this metal, according to Wedgwood, melts only in a de¬ 
gree of heat equal to 3807. It is alfo a well known faft, 
that the elafticity of aqueous vapour is incomparably 
more increafed by any given increase of temperature than, 
that of any other (pecies of elaftic fluid. But as the 
elasticity or expanfive force of this fluid at the tempera¬ 
ture of 2i2°, is equal to the ordinary preffure of the at- 
nvofphere ; and as this ekjfticity is doubled by every in- 
creale of temperature equal to 30 0 of Fahrenheit, it be¬ 
comes eafy to calculate what the prodigious force of 
this vapour mult be when railed to the temperature 
of 3807°. 
When gun-powder takes fire, azotic gas is difengaged, 
which expands aftoniftiingly in recovering its liberty ; 
and how far the dilatation may go, cannot be known, 
on account of the great heat which accompanies the 
combuftion. There is alio a decompofition of water, 
and hydrogen gas is difengaged with elafticity: by the 
decompofition of water we have carbonic acid gas and 
fulphurated hydrogen gas, which occafions the fmell pe¬ 
culiar to burnt gun-powder. 
We fliall in this place mention that mixture of nitre 
and fulphur, which is called ponjodur offufibn. It confifts 
of three parts of nitre, one of fulphur, and one of law- 
duft. A fmall quantity of this powder is put into a nut- 
fliell, with a fmall piece of copper money rolled up ; 
the piece is covered with the fame powder, which being 
fet on fire, barns rapidly, and melts the coin, without 
burning the flieil, which is only blacked. It is ne- 
celfary, however, to plunge the whole in water as foon as 
the powder has ceaied to burn. 
Njtrat of potafli is decompofed by fulphuric acid ; the 
belt method of procuring nitric acid, is as follows: Put 
into a glafs tubulated retort, ico parts of very pure ni- 
trat of potafli, ami feventy-five parts of concentrated fui- 
phuric acid ; place the retort on a land-bath, as Ihewn in 
the Cliemiitry Plate ¥. at A, fig; 2..and fix thereto a bal¬ 
loon, or receiver; with two necks, B; fix to the lower 
extremity of this balloon a tube, one end of which, form¬ 
ing a right angle with the other, is to be plunged into 
the centre of a bottle with three necks, C ; each of the 
fide openings of this bottle receives a lyphon, which goes 
into another bottle, placed on each fide of the firft, as at 
F> D ; thefe two collateral bottles are joined by lyphons 
to two (imilar ones, EE, whole lateral apertures, a a, are 
left unftopped. The firll bottle is commonly left empty ; 
the collateral bottles contain a certain quantity of water, 
in which is plunged the iowermoft and longelt extremity 
of the tube, which goes from the one to the other; the 
upper par.t of the bottles is left empty , and, when the 
acid vapour paffes above the water of the firft bottles, it 
is carried by the tubes into the fucceeding ones. The 
apparatus mult be well luted : the retort is to be heated 
by degrees; and, at the end of the operation, let the heat 
be very ftrong, to prevent ablorption. 
There is a principal advantage derived from this in¬ 
genious 
