776 / 1042
G U N
ihem
appclT
more cxaél Ihao Ihe comnJon Olelhod of
Iryi og
10
\Vh,11Jillaoee a eenain weighl of powder
\ViII
.hrowa ball (rom a
mUa(~I .
Thae has beCO mueh lalkof awhile pnwdl'r, whieh,
ir
il anf\\'er<d Ihe eharaélN given il, m;ghl be a d. n·
gerous eompor,lilln; for Ihe)'
pr~tcnd
Ih,1I Ihis white
powder wilJ Ihro", a ball as fa,. .s Ihe bLHk, yet \Vi,h·
OUI m.kiog a repon; bUl nooe of Ihe "hile powdcr
\Ve hlVe feen, fays Dr Shaw, anfwers 10 this ehirae·
ter; beiog, as lI'e appreheod, COOlOlQl1ly made eilher
wilh touchwood or comphor, iofiead of coal.
Oh/trua/ionJ on ¡hejorce
o/
GUN '
PO\\'D ER.
GUO'pOIV'
der, fircd eilher in vaeuum, or in :tir, produces, by
it! explolieo, a permaoeol ellflic Buid. For if a red·
hel iroo be included io a receim, after beiog exhaull·
ed, and
gllO
powder be lel rall 00 Ihe iroo, Ihe pOIV'
der will take lire, aod Ihe mercurial gage wilJ fad·
deoll' defceod upoo Ihe explor,oo ; aod thollgh il im·
medim!y afceods
~gaio,
yel il \\'ill oem rife 10 the
height il firfi lIood at, bUl will rooliolle drprcfl',d by
a fpace proponiooed 10 Ihe quaolill' of guo powder
which was lel fall on Ihe iroo.
The f. me produélion likewife takcs place, wheo
guo powder is fired in the air : for if a fmall quantilY
of pGwder be placed io the IIpper part of a gl,fs tube,
and the lower pan of the tul'e be io'mrrged io wa·
ter, aod the water be made
10
rife fo Dear the tOP,
Ihat oDll' a Imall ponion of air is left iR that rat l
"here the guo.powder is placed; if ia this {¡I uatioo
Ihe commuoicalioo of Ihe upper par! of the lube
~vith
the external air be dofed, lIod the powder be fired,
whieh " ..ill ear,ll' be dooe br a buroiog.glafs, the wa·
ter II ill io Ihis exp'eriment defeeod upoo Ihe exploGon
as the quickfi lver did io the
Ida ;
20d
1\
ill always con–
tioue deprefi(d btlow the place at which it fi ood be·
fore the explc{¡oo; aod the quaotity of Ihis depref.
fion will be grealer, if the quan!i ly of powder be io·
creafed, or the diameler of Ihe tube be dimioifiled,
From whence il is proved, that as well in air as in a
"acuum, the explofioo o( fired powder produces a
permaneol elafiic fluid.
It
alfo appears fromexperi.
meot, thal the el.llicity or prefl'ure of the fluid pro·
oucld by Ihe firiog of guo powdlT, is.
(11.'/,,.iJ
p",i.
hll,
direé:ly as its denfi ll'. This follo",s fromheoce,
thal if io the fame recriver a double quaolily of
pOllder be
kt
f. lI, the mercury will fub{¡de twice as
flluch as io the firiog of a (¡ogle qcantity,
Todetermine the elafiicilYaod quaotityof tbis ela·
nic fluid, produccd from the explo{¡oD of agivroquao·
(¡Iy (If guo rowder, Mr Rubios premifcs, that the
d,P.iri!y of this fuid iocrcafes
~y
heal, aod dimioifllcs
by cold, io the fame manoer as Ihat of Ihe ai r ; aod
that the denr,ty of Il:is fluid, ar.d coo(equendy its
Ileinr.t, is the (ame with the weight of ao equal bulk
el
;ir having the f..o;e t1.fliciIY, 20d Ihe fame lemper·
~tll
c.
From thefe pri06plcs, aod froOl his especimeol',
(for , netail of whleh we mufl refcr the nader tOhis
1\111' Pr ir.ciplcs 01Cunoerl', io Scholium 10prop.!!.)
he COOdlIO,S, Ih't the fi l"d prodnccd by Ihe
firio~
of
!llo' Follcer lIillle -lo of Ihe weighl of the guo
pOli'-
G U N
d~r,
aoel Ihe ratio 0f Ihe refpeélivc bulks or the po'r
der, aod the Jl aiJ pro,lueed from it, VlIII be io round
oumber! l 10 2.1 4.
He.oce lI'e are certaio. Ih, t any quainitl'. of po\Vder
fi "d lO .ny co06ocJ (pdce, which il adcqumly fills,
excm, at the lofl,ot of il! explor,oo, ag,ioll Ihe
fides of the l'efl'c1s coolaining it, and the bodies it 1m'
pels before il, a force at
ICdíl
244 times gremr
Ih,~
Ihe elaflicity of commoo air ; or, which is the f,me
thiog, Ihao the p'cfl'ure of the alOlofphere; aod Ih"
without coor,dtrioz the great addition whieh Ihis
force I\'ill rece ive froOl Ihe violeot degree of heal
wilh \Vhich it
is
eodued at thal time, Ihe qnaotilY
of which allgmeolatioo is the oexl head of Mr Ro.
bin's eoquirl"
J:!e determioes thal Ihe elaflicilY of thz
air is aucmented wheo heated lO the eXlremell hw of
red hOI iroo, io Ihe proportioo of 796 10 194+; aod
fuppor,og Ihat Ihe Rame of fired guo·powder is OOt
lels hot thao red hot iroo, aod the elallicily of Ihe
air, aod coofequeotly of Ihe fl uid, geoeraled by the
explo{¡on, beiog augmeoted by the eXlremity of Ihis
h(al io Ihe ratioof 79610 194t, it follow!,
I~at
if 244
be augmeoted io this ratio, the refulliog oumber, which
is 999t, will delermioe bow maoy times Ihe elanicill'
of the fiame of fired PO' der exceeds the elafiieilYof
common air, fuppofiog il to be coofined in the fame
fpace which Ihe powdcr 611ed before it "'as fired.
Heoce theo, the a"(olule quantilY of Ihe pre{fure
exened by guo·powder at Ihe monleot of ils explo.
{¡oo mal' be affigoed: for fioce Ihe fluid theh geoera·
ted has ao e1allieity of 999t, or, ia rouod oumbers,
1000 timesgreater Ihao commOD air; aod r,oee COOl·
moa air, by its elafiicity, exrrrs a prefl'ure 00 any gi.
veo furface equ,1to Ihe wrighl of the iocumbeot at–
mofphere wilh which il is io
lquilibrio,
the prefl'u re
rxerted by fired powder, before it has dilated itfelf,
is 1000 times grealer Ihan the prefl'ure of the at·
. mofphere; aod eoofequeotly Ihe quantityof thisforce
00 a furface of ao loeh fquare amouots lO abo"e fix
tun weight, whieh (orce however dimioilhes as the
Huid dilates itfdf. The v¡riatioos of Ihe deor,IY of
the atmofphere does not aoy way aher Ihe aElioo of
powder by ao)' experimeol Ihal caDbe made,
BH
Ihe moiflu re of the air has 'a very great ioflueoce 00
tire forcr of il : for tha! quaolily whirh io a drl' fea·
fon1I'0uld commuoicate 10 a bullet a velocilY of 1700
(eel io ooe fecood, will not io damp wealher comOlu·
oicate avelocity of more Ihao
12
Or 1300 fw in a fe·
cood, or eveo lefs, if Ihe powder be bad aod Deeli.
geotly kept.
The velocity of expaofioo of Ihe fiame of
~un·
powder, II'heo fired io a piece of .rtillery, Wilhoul
either bullet, or aoy oth" body before it, is
prodi~i.
ous. By the experimeots of Mr Robios, it feeolS
Ihis veloeity caooot be much lel! thao
¡OOO
fee! in a
fecood. This, however, mufi be uoderfiood of the
mofi aélive part of Ihe flame o For,.! Itas obfell'eJ
before, the clafiic fluid , io \Vhirh the ••9ivity of guo·
powder
eon(,JI~,
is ooly
T~
of Ihe fublh oce of Ihe
rowder, the rcmaioiog
,1,.
\l'ill io Ihe ex!,loli"o he
mixed wilh the ellllic part, aod lI'ill by ils
\l'er~hl
re·
lard