3 22 
G U N P O 
tier muft .be much greater than the preffure of 8192 at- 
mofplteres. At 722°, the elafticity will be equal to the 
preffure of 131,072 atmofpheres; and this temperature 
is lei's than the heat of iron, which is vifibly red-hot 
in daylight, by 355 0 :—but the flame of gunpowder 
has been found to melt brafs, which requires a heat 
equal to that of 3807^ of Fahrenheit ; 2730° above 
the heat of red-hot'iron, or 3805° higher than the tem¬ 
perature which gives to fleam an elafticity equal to the 
p re flu re of 131,072 atmofpheres. That there is in gun¬ 
powder water fufficient for fupplying the neceflary 
quantity of fleam, the author has very fatisfaftorily 
evinced : but we mtift not purfue his curious inveftiga- 
tiops any farther. iFhofe who want a fuller account of 
them, will find it either in count Rumford’s Memoirs, 
or in a very accurate abridgment of them, in the fir ft 
volume' of Nicholfon’s Journal of Natural Philofophy. 
To elucidate farther the deflagrating qualities and 
explofive force of gunpowder; MivR. Coleman, of the 
Royal Powder-Mills at Waltham Abbey, lias recently 
publifhed the following ingenious experiments, which 
we fliall liere recite'in his own words: 
“ Exper. i. —One hundred parts of compofition for 
gunpowder, gain from three to'fo ( ur or five parts in 
weight, by the water ufed at the mills. 
Exppr. 2.—This water appears to be totally got rid 
of by the fucceedlng procefles of manu fadhiring and 
ftove-drying; and therefore it follows that the only 
aqueous matter in gunpowder is what may be at firft 
contained in the ingredients. 
Exper. 3.— The ingredients, only pulverifed and 
mixed, have a very fmall explofive force. 
Exper. 4.—Gunpowder granulated after having been 
but a fliort time on the mill, has only acquired a por¬ 
tion of its ftrength. 
Exper. 5. — It is not till it has been the proper tifhe 
on the mill, and been properly made there, that it has 
obtained its full powers. 
Exper. 6.—The ftrength of gunpowder does not de¬ 
pend on the granulation, the duft of gunpowder after 
manufacture having nearly the fame force as when gra¬ 
nulated. 
Exper. 7. — Powder made in every refpedt the fame, 
but of two forts of charcoal, viz. pit and cylinder , is 
very different in ftrength : the cylinder charcoal ren¬ 
dering the gunpowder made therewith much fuperior 
to that made with pit charcoal. 
Exper. 8 . — Powder undried, in every ftage of ma¬ 
nufacture, is weaker than when dried. 
“If the compofition on a mill explodes by any acci- 
- dental caufe, fhortly after it has been put on the Hone's, 
it goes off with a very flight explofive force, princi¬ 
pally in flame : but if it has been on an hour or two 
under the runners, and then explodes, it more or lefs 
deftroys the mill, throwing the boards of the covering 
and fides to a confiderable diftance. I fhall here ftate a 
circumftance that happened, which, although not im¬ 
mediately connedted with the fubjedt, may ferve as a 
ftrong illuftration of one branch of philofophy. On 
the explofion of the powder in a mill which Had been 
on about two hours, the mill was wholly unroofed and 
the fides blown out. The doors and windows of the 
mills on the oppofite fide of the ftrearn were forced 
open outwards , and the nails, &c. drawn. 
“In refpedt to the fpecific gravity of gunpowder, 
count Romford ftates, that ‘ a cubic foot of water, 
holding 1000 ounces, will hold 1077 ounces of fine 
grain powder, well beaten and fliaken together; aud 
that the real fpecific'gravity of the folid grains of gun¬ 
powder is as, 1868 to 1000.’ I have, by repeated trials, 
found that the denfity of powder varies confid'erably 
from various caufes in manufacturing, for which reafon 
no exaEl table of the fpecific gravity can be given; but 
1 muft obfejrve, that the above, as given by count Rom¬ 
ford, is the gredtejl it will ever attain, in my opinion. 
WDER, 
I have never feen any fo much, and I have frequently 
feen it lejs, than that of water. 
“In the foregoing account I have confined myfelf to 
a Ample relation of fadts, from a confideration of which 
the following obfervations are co'rredtly deduced : iff. 
That the explofive force of gunpowder depends very 
materially on the pujity of the carbon employed. (Ex¬ 
per. 7.) 2d, That the mixture only of the ingredients 
does not make that thorough incorporation neceflary for 
the proper combuftion and explofive effects of gun¬ 
powder. (Exper. 3, 4, 5; 6.) 3d, That the lefs moif- 
ture there is'in gunpowder, the ftronger is 'its' effedt. 
This is clear, from gunpowder which has attradled any 
degree of humidity being weaker than when firft made. 
“ I fliall now beg to fiibmit fome ideas that occur to 
me from a confideration of the whole of the circum- 
ftances I have related, and from what may be deduced 
from an examination of the component parts of gun¬ 
powder. It .appears to me that no part of the explo¬ 
five force confifts in elaftic vapour, formedy by the 
combuftion, from water contained in it. So fm’all a 
portion of water is in the ingredients, and I have ob¬ 
served that not any is gained in the manufacturing', that 
I cannot jconcqive any water is carried off undecom- 
pofed, bj.it: that it is converted, into hydrogen and oxy¬ 
gen gafes. Mr. Cruickfliank obferves, ‘after the ex. 
plofion of gunpowder over mercury, no water is feen.* 
I am of opinion, that the explofive force of gunpowder 
confifts wholly in the feveral gafes formed by the com¬ 
buftion ; and that, the quicker it takes fire, the more 
gas is generated in a given time, and its force coafe- 
quently augmented. Lavoifier obferves, its effedt is in- 
creafed by the quantity of caloric difengaged at the 
moment qf deflagration. Jt feems, therefore, that the 
combuftion is carried on by the oxygen fupplied from 
the nitre ; that this gas is inftantly taken up by the fill- 
phur and carbon; and, converting tliofe fubftances into 
carbonic and fulphureous acid gafes, azotic gas being 
at the fame time liberated from the nitre, the water 
which may be in the nitre, and alfo that which is in 
the charcoal, is decompofed ; and the oxygen taken up 
by the carbon and fulphur and the hydrogen, fet free. 
The force arifing from tliefe gafes, with the increafed 
elafticity they receive from the increafe of temperature 
caufed by the combuftion, is furely fufficient to account 
for the effedts we obferve in gunpowder. 
“It may probably ferve to elucidate the fubject, if 
we eonfider a little more minutely what the component 
parts of gunpowder are, from chemical analyfis. 
Nitre. One hundred parts ofnitre, according to 
Kirwan, confift of 
Potafli - - 51 * 8 T 
Acid - - 44’o ldried in a heat of 70 0 , 
Water of compofition y 2 J 
y “ By feveral experiments, I have found that nitre 
which had been dried at 70 0 , lofes 3 per cent, in melt¬ 
ing. Lavoifier fays, one hundred parts of nitre confift of 
Potafh 49, dry acid $i s o; and that this dry acid is. 
Oxygen - 49-6 
Azot - 10-4. 
Charcoal, according to Lavoifier, abforbs 2-5714 
of oxygen in combuftion. From feveral experiments 
which I have made, I have, reafon to conclude, that 
charcoal, when ufed, contains about one-eighth part of 
water, which it has abforbed. 
Sulphur, according to Berthollet, requires for 
every hundred parts 36-8 of oxygen to form Sulphuric 
acid ; of courfe, a finallcr quantity of oxygen would 
be neceflary for their converfidn into fulphureous acid 
gas: I fliall take this at 30 per cent, which is probably 
not far from the truth, and, at any rate, near enough 
for our prefent purpofe. No experiment, that I know 
of, has been made to afeertain this point. 
“ Admitting the foregoing obfervations to be tolera¬ 
bly corredt, the following will turn out to be the quan- 
. tities 
