G U N P C 
rials, fuperiority of the products, and fafety in the 
operations”—Hence it will be feen, that the procefs in 
manufa&uring gunpowder in Frgnce, differs very little 
from that which is now adopted in England. 
On the criterion of strength, undoubtedly depends 
the great fuperiority of gunpowder; and to effect this, 
the French chemifts fabricated a gunpowder in which the 
marine or muriatic acid, which detonates with aftoni filing 
violence, was fubftituted for nitre ; and it was found to be 
of at leaft<&a£/e the ftrength of common gunpowder. After 
a feries of experiments had been made with it, its ufe 
was prohibited, on account of the great danger attend¬ 
ing its eafy deflagration ; fince it was found to explode 
by the flight ftroke of a hammer, without even the aid 
of the fmalleft fpark of fire. Dr. Hutton made feveral 
experiments with a preparation of this gunpowder at 
WoolwiGh, fufRcient to afcertain the above facts, as 
well as to manifeft its inutility for any naval or military 
purpofe whatever.—For the chemical properties of the 
marine or muriatic acid, fee the article Chemistry, 
vol. iv. p. 217-219-237. 
On the EXPLOSIVE FORCE of GUNPOWDER. 
To underftand the force of gunpowder, it mtjft be 
confidered that, whether it be fired in a Vacuum or in 
air, it produces by its explofion a permanently elaftic 
fluid. See Philof. Tranf. N° 295; and Haukfbee’s 
Phvf. Meehan. Exp. p. 81. It alfo appears from ex¬ 
periment, that the elaflicity or preffure of the fluid 
produced by the firing of gunpowder, is, emteris paribus, 
direftly as its denfity. To determine the elaflicity and 
quantity of this elaftic fluid, produced from the explo¬ 
fion of a given quantity of gunpowder, Mr. Robins 
premifes, that the elaflicity of this fluid increafes by 
heat, and diminifhes by cold, in the fame manner as 
that of the air; and that the denfity of this fluid, and 
confequently its weight, is the fame with the weight of 
an equal bulk of air, having the fame elaflicity and the 
fame temperature. From thefe principles, and from 
the experiments by which they are eftablifhed, he con¬ 
cludes, that the fluid produced by the firing of gun¬ 
powder is nearly three-tenths of the weight of the gene¬ 
rating powder itfelf; and that the volume or bulk of 
this air or fluid, when expanded to the rarity of com¬ 
mon atmofpheric air, is about two hundred and forty- 
four times the bulk of the faid generating powder. 
. Count Saluce, in his Mifcel. Phil. Mathem. Soc. Priv. 
Taurin. p. 125, makes the proportion as 222 to 1 ; 
which, he fays, agrees with the computation of Meffrs. 
Hauklbee, Amontons, and Belidor. 
Hence it appears, that any quantity of powder fired 
in any confined fpace, which it adequately fills, exerts, 
at the inftant of its explofion againft the fides of the 
weffel containing it, and the bodies it impels before it, 
a force at leaft two hundred and forty-four times greater 
than the elaflicity of common air, or, which is the fame 
thing, than the preffure of the atmofphere ; and this 
without confidering the great addition arifing from the 
violent degree of heat with which it is endued at that 
time; the quantity of which augmentation is the next 
head of Mr. Robins’s enquiry. Fie determines, that 
the elaflicity of the air is augmented in a proportion 
fomewhat greater than that of four to one, when heated 
to the extremeft heat of red-hot iron; and fuppofing 
that the flame of fired gunpowder is not of a lefs de¬ 
gree of heat, increafing the former number a little more 
than four times, makes nearly one thoufand; which 
fliews that the elaflicity of the flame, at the moment of 
explofion, is about one thoufand times ftronger than the 
elaflicity of common air, or than the preffure of the 
atmofphere. But, from the height of the barometer, 
it is known that the preffure of the atmofphere upon 
every fquare inch, is on a medium i4$lb. and therefore 
one thoufand times this, or 147501b. is the force or 
preffure of the flame of gunpowder, at the moment of 
Vol.IX. No.571, 
W D E R. 121 
explofion,’" upon a fquare inch, which is very nearly 
equivalent to fix tons and a half. This great force, 
however, diminifhes as the fluid dilates itfelf, and in 
that proportion, viz. in proportion to the fpace it occu¬ 
pies, it being only half the ftrength when it occupies a 
double fpace, one-third the ftrength when triple the 
fpace, and fo on. 
Mr. Robins fuppofes the degree.of heat above-men¬ 
tioned- to be a kind of medium heat; but that, in the 
cafe of large quantities of powder, the heat will be 
higher, and in very fmall quantities lower ; and that 
therefore in the former cafe the force will be fomewhat 
more, and in the latter fomewhat lefs, than one thoufand 
times'the force of the atmofphere. He farther found 
that the ftrength of powder is the fame in all variations 
in the denfity of the atmofphere. But that the moifture 
of the air has a great effeft upon it; for the fame quan¬ 
tity which in a dry feafon would difeharge a bullet with 
a velocity of one thoufand feven hundred feet in one 
fecond, will not in damp weather give it a velocity of 
more than one thoufand three hundred feet in a fecond, 
or much lefs, if the powder be bad, and negligently 
kept. See Robins’s Tradls, vol. i. p. 101, &c. Far¬ 
ther, as 'there is a certain quantity of water, which, 
when mixed with powder, will prevent its firing at all, 
it cannot be doubted but every degree of moifture muft 
abate the violence of the explofion ; and hence the ef¬ 
fects of damp on powder are not difficult to account for. 
It is to be obferved, that the moifture imbibed by 
powder does not render it lefs adtive when dried again. 
Indeed, if powder be expofed to very great damps 
without any caution, or when common fait abounds in 
it, as often happens through negligence in refining the 
nitre, in fuch cafes the moifture it imbibes may perhaps 
be fufficient to diffolve fome part of the nitre; which 
is a permanent damage that no drying can retrieve. 
But when tolerable care is taken in preferring powder, 
and the nitre it is compofed of has been well purged 
from common fait, .it will retain its force for a long 
time; and it is faid that powder has been known to 
have been preferved for fifty years without any apparent 
damage from its age. 
The velocity of expanfion of the flame of gunpow¬ 
der, when fired in a piece of artillery, without either 
bullet or other body before it, is prodigioufly great, 
viz. feven thoufand feet per fecond, or upwards, as ap¬ 
pears from the experiments of Mr. Robins. But M. 
Bernouilii and Mr. Euler fufpect it is ftill much greater. 
And Dr. Flutton fufpeefs it may not be lefs, at the mo- 
hpent of explofion, than four times as much.—Gount 
Rumford, in a fatisfadtory and ingenious calculation, 
has (hewn, that the force of the elaftic fluid generated 
in the combuftion of gunpowder, enormous as it is, 
may be eafily explained on the fuppofition that it depends 
folely on the elaflicity of watery vapour, or fleam. From 
experiments made in France in 1790, it appears that the 
elaflicity of fleam is doubled by every addition of tem¬ 
perature equal to 30° of Fahrenheit’s thermometer. 
As the heat generated in the combuftion of gunpowder 
cannot be lefs than that of red-hot iron, it may be fup- - 
pofed equal to 1000 0 of Fahrenheit’s fcale : but the 
elaftic force of fleam is juft equal to the mean preffure 
of the atmofphere, when its temperature is equal to 
that of boiling water, or to 212 0 of Fahrenheit’s ther¬ 
mometer ; confequently 2i2°-t-30°=24@ 0 will reprefent 
the temperature, when its elaflicity will be-equal to the 
preffure of two atmofpheres ; and, purfuing the calcu¬ 
lation, at 602°, or 2 0 above the heat of boiling linfeed 
oil, its elaflicity will be equal to the preffure of 8192 
atmofpheres, or above eight times greater than the ut- 
moft force of the fluid generated in the Combuftion of 
unpowder, according to Mr. Robins’s computation : 
ut the heat in this cafe is much greater than that of 
602° of Fahrenheit ; and therefore the elaflicity of the 
fleam generated from the water contained in the pow- 
I i der 
