GUNPOWDER. 
ee n 
is fluid is elattic, is ae Seam ahenniakeadis oh tit 
yes Rages nce the quantity of matter contained in 
this fluid could not by its gravity alone have funk the quick- 
pr by the leaft — quantity ; alfo from its extending 
itfelf through any fpace, however great, the experiment 
fucceeding in siidier a Lies or {mall receiver, only the larger 
-the receiver the lefs will be the age of the mercurial 
‘age ' the fame quantity of powder ; preffure of the 
ate as its a Seeamitees: ee 
. Tranf. No. : 
The { 
fred (which may eafily be done by a burning-glafs) the 
will, in this experiment, defcend on the explofion, as 
Shen did in, the laft, and will always continue de- 
adghe the place at which it. ftood before the explo- 
5 andthe quantity of this depreffion will be greater, if 
te ec — be increafed, or the diameter of the 
aie m whence it is proved, that as well 
in certain circumftances, is now a well known 
sadimeowtetible te. See Air 
‘ om experiment, that the elaiticity or 
‘preffure of ‘the. fluid produced by the firing of gunpowder, 
, direétly as its deity. “his follows from 
that if in the Sea ee a double. epsicp of 
owder be let fall, mee ublide as much 
as in the firing of a oe yaccFer sas vapour pro- 
uced from ee uantity, bein ng erence in 
“receiver, double the denfity o: P80 pro- 
Guced from the ity ; whence oe elafticit 
receivers, are reciprocally as 
Bfet pie oi contequetly, as the den- 
, +9 determine the-elaftic ity and quantity ab this ge 
to i the explofion of a given quanti 
e, 
es by a and. dimimifhes by es in the 
‘Manner as that of the air (a fa&t confirme 
a confequently its weight, is the fame. 
: — on Sa a ilk of air, having the fame elafticity 
i ere 'temperat re. thefe principles, and from 
Shoe which they se eax gp aes for a — 
Aenean axpelenere: 
ies es; he. u 
firing of aetna that the fluid pr 
eon, SUnpowder wi be nearly 2 or the wei <4 
“Of the > ‘Sunpowder ; and the emul a eve 
a ‘Tumbers, tn a4 roe 
Ton aie it 
duces common air 3 
ey en Mr. Robins premifes, ic the elafticity of thi our fe 
he fays, agrees with a computation of Meffrs: Haukfbees 
Amontons, and Belido 
ence we are sti that pigs quantity of powder fred 
in any confined fpace, which it adequately fills, seri at 
the inftant of its explofion againft the fides of the wv 
containing it, and the bodies it impels before it, a eae 
at leaft 244 times greater than the elafticity of common 
air, or, which is the fame thing, than the preffure of the 
atmofphere ; and this without confidering mer rie ad 
dition which this force will receive from olen 
of heat with which it is endued at that rig ; ae qua 
tity of which augmentation is the next head of Mr. Robin's 8 
He determines that the elafticity of the ai 
fined in the fame ge which the A filled oy fe oo 
d. 
Hence then the abfolute Svergg: of the preffure 
by t the m of its explofion, may be 
at 
aligned 5 for fince the uid. "aes generated has an elafti- 
city 9993 or, in round numbers, 1000 times greater than: 
and fince common air, by its gas igh exerts: 
a preffure on any. given furface equal to the w the 
_ moip! Sk ated eae 
he preffure seine by fired powder, before it has dilated 
itfelt is 1000 times greater than the preffure of. the at- 
ake ere, ear ‘confequently, the. quantity of this ee 
on a furface of an inch fquare, amounts to above fix e 
weight ; pps force, however, diminifhes, as. the fluid. 
es It: 
Though it has here been fuppofed, bee go heat ‘of gun- 
der, when fired in any « Yo i8. “4 
 abipyghe Ge ‘a- peas 
a gradual.augmentation to 
nd diminifbing it. when a quantities are 
Bra. of Gunnery,.in Robins’s Math. 'Traéts, vol. i. 3D; 59>. 
&e Ae | 
‘Gunpowder i is. fappofed to explode at about 600° Fahr. 
but if heated to fit below that. of faint 
oe tf wl oly bur leaving the nitre 
obferve, that that the variations. of the _deniity of 
e do not any. way. alter. She alin Ht age 
