ON GUNPOWDER.
Gunpowder being the base on which the superstructure of this treatise is
to be raised, the history, the use, and the nature of this explosive
compound, are here placed in the foreground; as it is essential to the
correct conception of the various matters hereafter to be explained,
that the reader be first acquainted with the one grand principle in
fire-arms, the propellant power of explosion.
Gunpowder, whether considered relatively to engines of war, or to those
arms used with so much success in the sporting field, has, since its
first _introduction_, been a source of much and frequent discussion. In
regard to its origin, we shall not much enlarge, nor repeat the many
suppositions and conjectures promulgated by the searchers after
antiquarian evidence.
The inhabitants of India were unquestionably acquainted with its
composition at an early date. Alexander is supposed to have avoided
attacking the Oxydracea, a people dwelling between the Hyphasis and
Ganges, from a report of their being possessed of supernatural means of
defence: “For,” it is said, “they come not out to fight those who attack
them, but those holy men, beloved by the gods, overthrow their enemies
with tempests and thunderbolts shot from their walls;” and, when the
Egyptian Hercules and Bacchus overran India, they attacked these people,
“but were repulsed with storms of thunderbolts and lightning hurled from
above.” This is, no doubt, evidence of the use of gunpowder; but as it
is unprofitable to investigate this subject further, we shall merely
confine ourselves to the European authorities.
Many ascribe the discovery of gunpowder to Roger Bacon, the monk, who
was born at Ilchester, in Somersetshire, in the year 1214, and is said
to have died in 1285. No doubt he was by far the most illustrious, the
best informed, and the most philosophical of all the alchemists. In the
6th chapter of his Epistles of the Secrets of Arts, the following
passage occurs--“For sounds like thunder, and flashes like lightning,
may be made in the air, and they may be rendered even more horrible than
those of nature herself. A small quantity of matter, properly
manufactured, and not larger than the human thumb, may be made to
produce a horrible noise; and this may be done many ways, by which a
_city_ or an _army_ may be destroyed, as was the case when Gideon and
his men broke their _pitchers_ and exhibited their lamps, fire issuing
out of them with great force and noise, destroying an infinite number of
the army of the _Midianites_.” And in the 11th chapter of the same
epistle occurs the following passage:--“Mix together saltpetre with
_luru mone cap ubre_, and sulphur, and you will make thunder and
lightning, if you know the method of mixing them.” Here all the
ingredients of gunpowder are mentioned, except charcoal; which is,
doubtless, concealed under the barbarous terms used; indeed, the
_anagram_ is easily converted into _carbonum pulvere_, with a little
attention.
This discovery has also been attributed to Schwartz, a German monk, and
the date of 1320 annexed to it; a date posterior to that which may be
justly claimed for Friar Bacon; and as accident is stated to have been
the means by which he discovered it, we have taken that incident as the
subject of an illustration.
[Illustration]
Mr. Hallam, referring to the authority of an Arabic author, infers that
there is no question that the knowledge of gunpowder was introduced into
Europe through the means of the Saracens, before the middle of the 13th
century; and no doubt its use then was more for fireworks, than as an
artillerist projectile force. There is good evidence, too, that the use
of gunpowder was introduced into Spain by the Moors, at least as early
as the year 1343. Now, as Roger Bacon is known to have been an Arabic
scholar, it is not at all unlikely that he might have become acquainted
with the mode of making the composition, and also with its most
remarkable properties, by perusing some Arabian writer with whom we are
at present unacquainted.
This invention, by which the personal barbarity of war has certainly
been diminished, is, when considered as a means of human destruction, by
far the most powerful that skill has ever devised, or accident
presented; acquiring, as experience shows us, a more sanguinary dominion
in every succeeding age, and subserving all the progressive resources of
science and civilization for the extermination of mankind: which, says
Mr. Hallam, “appals us at the future prospects of the species, and makes
us feel, perhaps, more than in any other instance, a difficulty in
reconciling the mysterious dispensation with the benevolent order of
Providence.”
The composition of gunpowder, as regards the proportions of the
ingredients, has not undergone any material alteration; the chemical
proportions of the ancients being nearly those of the present day.
Gunpowder is an explosive propellant compound, consisting of saltpetre
or nitre, charcoal, and sulphur. The terms, _explosive_ and
_propellant_, are not here used as synonymous--they are not convertible;
for a chemical mixture may possess the _explosive_ power in a much
higher degree than the _propellant_: fulminating gold, silver, and
mercury, are dreadfully explosive; but they have not the same
projectile force, nor can they be used as a substitute for it. Several
experiments have been made with compounds of this nature, but the result
is the reverse of what might be expected. Nothing can resist the
exceeding intensity of the action of fulminating powder; a shot, when
fired in this way, is not projected as by gunpowder, but is split into
fragments by the velocity of its explosion, as we shall hereafter have
occasion to show.
Nitre, or saltpetre, is strictly the essence of gunpowder. It is a
triple compound of oxygen, nitrogen, and potassium. The chemical action
of those elements on each other, and the play of affinities between them
at a high temperature, occasion the immense effect produced by gunpowder
on the application of fire or heat. By universal consent, sulphur is
included in the mixture, but it is not absolutely necessary for the
“propellant power;” for nitre and charcoal only will generate effects
similar to the compound with sulphur. Gunpowder made without sulphur
has, however, several bad qualities; it is not, on the whole, so
powerful, nor so regular in its action; it is also porous and friable,
possessing neither firmness nor solidity. It cannot bear the friction of
carriage, and in transport crumbles into dust. The use of sulphur,
therefore, appears to be not only to complete the mechanical combination
of the other ingredients, but being a perfectly combustible substance,
it increases the general effect, augments the propellant power, and is
thought to render the powder less susceptible of injury from atmospheric
influence.
“There is one good reason,” says the Edinburgh Encyclopædia, “for the
use of sulphur, although it does not contribute to the production of any
elastic fluid. The carbonic acid which is generated would doubtless
combine with the potash, if it were not for the presence of the sulphur,
and thus so much elastic fluid would be lost. That this is the case we
know to be true, from the fact that carbonate of potash is always formed
when nitre is decomposed by charcoal alone, which I shall almost
immediately show.” This certainly would be the case, to a certain
extent, with gunpowder without sulphur--some carbonate of potash would
be formed.
The sulphur, we have no doubt, from experiments we have made on this
subject, is, in part, engaged during the explosion of gunpowder in
expelling the sixth proportion of oxygen from the potash, so as to
combine with the potassium, to form a true sulphuret of that metal. This
fact is easily ascertained, from the circumstance that no sulphuretted
hydrogen can be detected, by the most delicate tests, coming from the
residuum left after firing gunpowder, until moisture has gained access
to it. The bad smell which arises sometime after the burning of
gunpowder, is occasioned by the decomposition of the moisture which the
sulphuret of potassium attracts from the atmosphere; giving rise, by
this decomposition and liberation, to the fœtid foul gas, called
sulphuretted hydrogen, and the production of potassa, or the oxide of
potassium.
A commission of French chemists and artillerists was appointed by the
Government, in the year 1794, to experiment upon the best proportions
and constituents of gunpowder for the use of the French service. The
following were the proportions of five different kinds prepared at the
Essonne works:--
---+------+---------+--------+----------------------
No.|Nitre.|Charcoal.|Sulphur.| ----
---+------+---------+--------+----------------------
1 |76·00 | 14·00 | 10·00 |Powder of Bâe.
2 |76·00 | 12·00 | 12·00 | „ Grenelle.
3 |76·00 | 15·00 | 9·00 | „ M. Morveau.
4 |77·32 | 13·44 | 9·24 | „ Ditto.
5 |77·50 | 15·00 | 7·50 | „ M. Keffault.
---+------+---------+--------+----------------------
The first and third, after 200 discharges with the proof mortar, were
declared the strongest, and the third proportions were adopted at the
recommendation of the commissioners. Some few years elapsed, and the
first, owing to its better keeping quality, was substituted, as it
contained less charcoal, and a little more sulphur. The French
Government having always been extremely impressed with the value of
durability in gunpowder, they have since returned to their ancient
proportions: 75 nitre, 12-1/2 charcoal, 12-1/2 sulphur. The charcoal,
the absorbent of moisture, being further reduced, and the sulphur, the
preserving ingredient, being increased in the same ratio.
“Mr. Napier tried a small quantity made of nitre and charcoal only, and
was much surprised to find it project a shot as far as the best powder
made in the usual manner. It is found that, in small charges, sulphur is
advantageous; but, in charges of several ounces, the projecting force is
as great without as with it. Therefore, under certain circumstances,
sulphur may be dispensed with; but to make a good gunpowder, nitre and
charcoal are indispensable.”
Amongst the brilliant discoveries of modern chemistry may be classed the
development of the fact, that a chemical combination, to constitute the
same compound, always takes place in definite and unalterable ratios. To
select one example out of a multitude: one atom of carbon combining with
two atoms of oxygen produces the gas; because more would answer no
useful end. So, with reference to the sulphur, if it enter into
combination only with the potassium--the base of the nitre--the sulphur
should be in that proportion to form the sulphuret of that metal; and in
this case there would be no superfluity, for that would only add to the
weight of the charge of powder, and diminish its absolute and effective
energy. The view of the case which we have taken supposes only two
combinations, viz. carbon with oxygen, and sulphur with potassium.
Should there be a more diversified play of affinities, and the several
elements of the powder enter into more complicated action, accurate
analysis would conduct us through all difficulties, and point out what
the proportions of the ingredients ought to be in order to sustain that
action, and to produce a perfect ultimate result.
We thus perceive how analysis bears upon the case. We can see by such
reasoning on the subject, that, theoretically, there can be but _one set
of proportions calculated to produce the best and strongest gunpowder_,
and that those proportions must depend upon the established and unerring
laws of nature. The proportions, then, for gunpowder, by these
considerations, will be those in which the carbon will just consume the
oxygen of the nitre, and combine with the sulphur as much as will
exactly saturate the potassium. This will be effected by an atom each of
nitre and sulphur, and three atoms of carbon; or nitre 75·5, charcoal
18·8, and of sulphur 11·8.
In the present improved state of chemical science, when the nature of
the bodies comprising gunpowder is so well known, as well as the
compounds resulting from their action on each other, the proportions we
have named may be taken as the best for practice.
The charcoal should, in particular, not be less than the nitre, as the
smallest portion less than the whole atom would be the same as to leave
out the whole atom, in which case there would be no carbonic oxide
formed. If, for example, instead of the proportions of nitre 75·5,
charcoal 16·2, sulphur 15, the carbon were 16, then there would be 4·2
of carbon left in the residuum, and no carbonic oxide would be formed,
since bodies cannot unite but in definite proportions.
From these considerations we can perceive the reason why a small
proportion of carbonic oxide is always formed during the decomposition
of nitre by charcoal; for it will be evident, that as the nitric acid
contains five atoms of oxygen, four of these must combine with two atoms
of carbon to form two atoms of carbonic acid, while the _odd atom of
oxygen_ is compelled to take another atom to form carbonic oxide. But
this is not the case in the combustion of gunpowder, as carbonic acid
and nitrogen are the principal gases generated.
These proportions differ from any other formula yet prescribed; and,
though different in a great degree from the proportions laid down by
various writers on the subject, the reasons which are here given, as has
been seen, are such as carry with them a conviction of their truth: for
there cannot possibly be any benefit arising from a greater quantity of
any of these materials than is absolutely necessary to form the
composition in question; and if the smallest quantity be above what is
requisite to consume the whole, that, however small it may be, is highly
detrimental to the effective energy of the mass. What we may here call
clean gunpowder, such as may be used with confidence for repeated
discharges of fire-arms of any description, is of the greatest
importance; therefore, it does not appear to us, that any given
proportions are so likely to accomplish that object as those before
specified.
TABLE OF COMPOSITION OF DIFFERENT GUNPOWDERS.
---------------------------------+------+---------+--------
Mills. |Nitre.|Charcoal.|Sulphur.
---------------------------------+------+---------+--------
Royal Waltham Abbey |75·00 | 15·00 | 10·00
France, National Mills |75·00 | 12·50 | 12·50
French Sporting |78·00 | 12·00 | 10·00
French Mining |65·00 | 15·00 | 20·00
U. S. of America |75·00 | 12·50 | 12·50
Prussia |75·00 | 13·50 | 11·50
Russia |73·78 | 13·59 | 12·63
Austria (Musket) |72·00 | 17·00 | 16·00
Spain |76·47 | 10·78 | 12·75
Sweden |76·00 | 15·00 | 9·00
Switzerland (Round Powder) |76·00 | 14·00 | 10·00
Chinese |75·00 | 14·40 | 9·90
Theoretical proportions as above |75·00 | 13·23 | 11·77
---------------------------------+------+---------+--------
Gunpowder consists of a very intricate mixture of sulphur, carbon
(charcoal), and nitrate of potash (nitre).
The proportions in which they exist are one equivalent of nitre, one of
sulphur, and three of carbon. The great explosive power of gunpowder is
due to the sudden development from its solid constituents of a large
quantity of gases; these gases are nitrogen and carbonic acid.
At the ordinary temperature of the atmosphere these gases would occupy a
space three hundred times greater than the bulk of the gunpowder used;
but owing to the intense heat developed at the moment of explosion, the
gases occupy at least 1,500 times the bulk of the original gunpowder.
The mixture, consisting of one equivalent of nitre, one of sulphur, and
three of carbon, would yield three equivalents of carbonic acid, one of
nitrogen, and one of sulphuret of potassium. The change may be
represented thus,--
S + C₃ + KONO₅ = 3 CO₂ + N + KS.
The only solid residue, therefore, is the sulphuret of potassium, and
this is the compound which produces the sulphurous odour on washing out
a gun barrel; water is decomposed, sulphuretted hydrogen and potash
being the result of the decomposition.
Now supposing the elements of gunpowder to exist in these proportions,
it is essential, in order to secure their perfect combination, and thus
to produce the largest possible volume of gas, that the elements should
be in the most minute state of subdivision. Chemical action is a force
exerted at insensible distances only, and chemical substances having the
greatest affinity for each other will not combine, unless their elements
are brought into immediate contact: thus oxygen and hydrogen may be
mixed together in the exact proportions to form water; but no chemical
combination will occur, simply because the ultimate particles of the two
gases are not sufficiently near to each other for their chemical
affinities to be brought into play; if, however, these gases are
subjected to very strong pressure, so as to bring their particles into
immediate contact, combination occurs, and the production of water is
the result.
In order to insure the perfect combination of the elements of gunpowder
the same conditions are necessary; that is to say, the ultimate
particles of the nitre, charcoal, and sulphur, must be brought into the
most direct contact, or the explosive power of the gunpowder will be
comparatively trifling. If, for instance, the nitre, charcoal, and
sulphur be pounded in a mortar, no explosion but a slow combustion will
occur when the mixture is ignited; so that unless this intimate mixture
of the elements is carefully attended to in the manufacture of
gunpowder, it is easy to see that the article produced will be of
comparatively little value.
It is evident then that if tons of the elements of gunpowder were stored
in a warehouse which accidentally caught fire, no explosion would occur
from the formation of gunpowder; though its ingredients would greatly
increase the rapidity of combustion.
This remark is elicited by the recollection of a fearful explosion which
took place at Gateshead in 1854.
It may be remembered that a warehouse caught fire from an adjoining
mill, and the explosion was supposed to have been produced by the
ignition of the elements of gunpowder stored in the warehouse in a crude
state. The upper story of the building contained a large quantity of
crude sulphur, and the basement story about the same quantity of nitre,
whilst chemicals of various kinds were stored in other parts of the
building; but according to the accounts published there was no large
quantity of carbon in the warehouse; nevertheless, a terrific explosion
took place, and after a lengthened investigation, the conclusion arrived
at was this: the sulphur melting, mixed with the nitre, gunpowder was
thus formed, and igniting, exploded, producing the terrible effects.
But gunpowder may be made without sulphur, whereas gunpowder without
carbon is an impossibility; and though the elements of gunpowder had all
been present, no explosion could have occurred, unless they had become
mixed in the intimate manner already described.
It is true some of the chemical substances in the warehouse might have
produced a fearful explosion: but a more plausible explanation is to be
found in the fact, that gunpowder was at that time much more valuable
abroad than at home; and it is quite possible that some kegs of
gunpowder might have been stored away in this warehouse, until a
convenient opportunity presented itself for their removal.
The foregoing remarks will serve to explain how it is that powder varies
so much in strength and quickness of fire. If the elements are
imperfectly incorporated, the powder can never be equal to that which is
properly made; and the manufacturer, having ascertained the best
proportions in which to mix the elements, had better improve his
machinery for incorporating them, rather than his knowledge of the
chemistry of gunpowder. These observations will also serve to explain
the apparent anomaly, that the French, and some of our other continental
brethren, are held to produce a much inferior sporting gunpowder to that
which is manufactured in old England.
Gunpowder is now made by all the sporting gunpowder manufacturers from
No. 1 to No. 5 grain; and it appears certain that a further increase in
the size of the grain would be advantageous; for many years of patient
and laborious experiment clearly show, that the old notion of gunpowder
being blown out of an ordinary sized gun in an unburnt state, is one of
the “purest of vulgar errors:” such a thing indeed cannot possibly
happen unless the powder be bad, or the gun _imperfectly made_, or
injudiciously charged.
I am satisfied that I am under rather than over estimate, when I assert
that six drams of ordinary sporting gunpowder may be beneficially and
completely exploded in a barrel of 14 bore, 2 feet 6 inches long, with a
resisting projectile one ounce in weight above it. This, however, being
more than a double charge for such a gun, cannot be pleasantly
practised; and it is only asserted by way of argument.
Assuming, then, for argument’s sake, that six drams of gunpowder are
exactly consumed in passing from the breech to the muzzle of a gun 2
feet 6 inches long, and that the shot, therefore, acquires its greatest
velocity as it leaves the muzzle, it follows that the ordinary charge of
2-1/2 drams will be wholly consumed before it has traversed half the
length of the barrel, and consequently the charge of shot must here
acquire its greatest velocity. It is certain, then, that the shot must
travel the latter half of the barrel at a diminished velocity, and its
velocity must continue to diminish as it passes up the barrel; for two
obvious reasons--1st, The column of air in front of the charge is more
condensed, and thus offers a greater resistance to the exit of the
charge; 2nd, The velocity is continually diminished by the increased
friction of the charge against the barrel.
The perfection of projectile science is to make the projectile acquire
its greatest velocity at the instant of leaving the muzzle; and if, by
increasing the size of the grain of gunpowder, we can diminish the
rapidity of its explosion--thus causing it to burn and generate fresh
gas up to the muzzle of the gun--the projectile will then acquire its
greatest velocity, and leave the gun to the best advantage: this is the
important point which has hitherto been overlooked, not only in
fowling-pieces, but in the expansive principle of rifles.
For artillery practice of every kind, whatever the weight of the
projectile, gunpowder of a granulation suited to the weight of that
projectile is essential, if we would produce the greatest possible
effect by the least expenditure of means.
In artillery, at this most important time in war’s history, no attention
whatever is paid to this essential principle. A long 10-inch gun, a
68-pounder, and a short 6-pounder are all charged with powder of the
same granulation; whilst by a more judicious use of gunpowder of
suitable granulation, the range might be extended, just as it is in
sporting arms, to nearly 20 per cent.
Artillerists seek to effect great range by doubling the weight of the
gun, and projectile monsters meet us at all points, to become in every
case “monster failures.”
I fear that the most important points have been entirely lost sight of.
Instead of ascertaining whether we have suited the projectile power to
the 8-inch or 56-pounder, so as to get work from it which is now done by
the 10-inch, we have, in our anxiety to get range, looked only to the
form or material of the gun; vital principles being totally excluded.
The construction of the gun being perfect, the question is, can the
expellant force be brought to an equal state of perfection?
In order to obtain the best results from a gun, the gun itself must be
perfect in construction, and the expellant force must be brought to bear
in the best possible manner upon the projectile; and this is to be done
by attending to the granulation of the powder, which must be suited to
the length of the gun, to its bore, and to the weight of the projectile.
Common-sense, engineering skill, will demonstrate, that according to the
weight of matter to be projected must be the nature of the expellant;
_accumulative_--until it has overcome the inertia of that matter,
_accelerative_--until it has communicated to it the highest state of
velocity its power is capable of effecting. If, on the other hand, it is
inferior to this, science has not extracted from it the full
_horse-power_ it contains; and we are uselessly expending force and
destroying our engines by undue pressure being exerted on one part, and
inferior pressure on another; whilst by a proper distribution of that
force, durability of the cannon is insured, and from twenty-five to
thirty per cent. more work may be obtained from an equal quantity of
powder, provided its granulation be judiciously selected according to
the area of the gun.
There is abundant proof that on this engineering question we have
hitherto worked by the “rule of thumb;” prejudice having been a
stumbling-block, which nothing but stern necessity will remove. The
authorities have but just discovered this, although their attention was
directed to it several years ago. In the year 1852, I produced before
the Small Arms Committee, at Enfield, a portion of gunpowder suited to
the expansive rifle; it was tried to a limited extent, and dismissed
with the remark, “We don’t think there is much in it.” Experience,
however, has demonstrated the truth of my observations, for, in all
extreme range shooting with the expansive or “Greenerian”-principled
rifles, not only is considerably greater _accuracy_ obtained with it,
but an _increase_ of range equivalent to fifteen or twenty per cent.
Another advantage of using gunpowder of a suitable granulation is the
absence of sharp recoil; and thus greater accuracy of range is
obtained--accuracy of range and steadiness of weapon being inseparable.
Large-grain gunpowder is not only a more effectual expellant than the
fine grain, but is much more safe to use, for by using it the risk of
bursting the barrel is much lessened; as a very simple illustration will
show. If we estimate the force generated by the usual charge of 2-1/2
drachms (I confine the question to the 14-bore gun, for uniformity) to
be 5,000 lbs., whether the powder be fine or coarse grain, it follows
that the fine powder, igniting so rapidly, will exert all its force on
the breech end of the gun; whereas the coarse powder, igniting less
rapidly, distributes this force over the whole length of the barrel:
hence the greater risk of a gun bursting with fine powder than with
coarse. If we suppose the fine powder to be entirely ignited when it
reaches half way up the barrel, then the force of 5,000 lbs. is exerted
on the lower half of the barrel; but if the coarser grain is not
entirely ignited until it reaches the muzzle, then the force of 5,000
lbs. will be distributed over the whole length of the gun.
But this is not all. The fine powder, igniting almost instantaneously,
exerts its force in all directions at once, and the barrel may burst at
the side before the charge has time to move; whereas the coarse powder,
igniting as it does more slowly, first lifts the charge, and then the
volume of gas behind it increasing as the powder becomes more thoroughly
ignited, sweeps the charge out of the barrel with a velocity increasing
towards the muzzle.
If time is not given for the charge to receive the full advantage of the
expansive force of the generated air, the force is exerted, not upon the
charge, but upon the barrel of the gun itself; and that time is
necessary for the full development of this force, is proved by the fact
that miners mix their gunpowder with sawdust, in order to diminish the
rapidity of its explosion and thus get the advantage of its force in the
distance: from the miners, then, let us learn how to obtain the greatest
benefit from this force, and waste it not.
There can be no doubt of the importance of this principle; little
progress has, however, been effected from want of scientific
illustration; let it be defined like that of steam power, and its
adoption will follow as a natural consequence.
For several years I have had gunpowder manufactured of various sizes, at
the sight of which most sportsmen would express their astonishment.
One objection held by sportsmen to the large grained gunpowder is that
it does not come up the nipple of the gun; now although I do not
consider this at all important, still if the specific gravity of the
gunpowder were increased by compressing 1-1/2, 2, or 3 grains of
gunpowder into the space of 1 grain, by means of hydraulic pressure,
this objection would at once be obviated; whilst at the same time, the
powder would be less liable to absorb moisture, or to become friable
with age: either of which conditions is incompatible with good shooting.
The granulating of gunpowder, to be of the greatest benefit, should be
on a uniform principle; the manipulation should be alike in all
particulars, but especially in that part of the process which determines
the specific gravity. The hydraulic pressure on the cake should be alike
in all cases: in fact, the various sizes of grain might be produced from
the same cake, and the desired object be thus obtained. But so long as
the practice is followed of producing large grain from less condensed
cake, the article produced will give unsatisfactory results; and the
advantages which might be attained, as my experience denotes, and which
would be of the greatest service, alike in sporting, rifle, and
artillery powder, will be nullified.
Great improvements are yet to be made, especially in the powder used for
artillery; whilst range, accuracy, and lessened recoils are points which
may be determined with almost mathematical precision.
Great fame is in prospect for any one who can grasp and handle well this
granulation principle; especially if he can define the sizes to be used
for different varieties of guns. Artillerists who contend that a medium
size grain, to suit all sizes of gun, is advantageous, might as well
contend that cannon of a medium size would be preferable to so many
different sizes, because, though we lose in range, accuracy, and recoil,
it would be more convenient to have but one sized gun.
In making large grained gunpowder, the manufacturers defeat one of the
main objects to be gained by granulation, from not subjecting it to the
same amount of pressure which is necessary for the granulation of the
very fine grain. In granulating very fine powder, it is necessary to
subject the cake to such an amount of hydraulic pressure as shall give
the mass a marble-like structure, or during the process of granulation,
the whole of it crumbles into dust; but the coarser gunpowder may be
granulated without subjecting it to this high degree of pressure, hence
each grain is more porous and of lesser specific gravity: a difference
which it is most important to avoid. It is clear, therefore, that
according to the present mode of manufacturing gunpowder, the large and
the fine grain are of very different kinds; the main difference being in
their specific gravities. Gunpowder of less density burns with greater
rapidity, because it is more open and porous; and if uniform density was
observed, the diversity in the size of the grain need not be so great;
whilst, at the same time, this anomaly might be avoided--that the same
measure of fine and large-grained gunpowder contains a difference of the
expansive element amounting to fifteen or twenty per cent. As gunpowder
is now manufactured, it is highly necessary in all comparative trials to
_weigh_, and not to _measure_ the charge, or the results will be
deceptive and worthless. The granulation question struggles with
undeserved difficulty. Gunmakers, either not understanding the question,
or constructing the chambers of their guns improperly, and not using
suitable nipples, decry the adoption of large-grained gunpowder; but
they forget the increased range obtained in the killing from their guns,
and the _éclât_ a long shot produces. In trials of guns at thirty or
forty yards, the difference in the shooting with fine and large-grained
gunpowder is not so apparent, and the maker exclaims, “Oh! the fine
powder shoots stronger, and as close as the coarse.” I admit this to be
the case, at short distances; but the great advantage of using the large
grain is sufficiently evident when shooting at forty-five, fifty, and
sixty yards, for then the fine grain entirely fails: simply from the
oft-repeated fact, that the fine powder is more of a propulsive, while
the large grain is an expellant force; so that according to the law of
resistance in aëriform fluids, the one is sooner reduced to medium
velocity than the other, which exerts its action more evenly. Powder of
larger grain is thus more suitable for the larger sizes of shot, and
would give an increased range in usual shooting, for the shot is kept
better together, and is projected to greater distances. A common way of
testing the quality of gunpowder is, to rub it between the hands, and
observe the darkness of the stain; the darker the stain the more
inferior the gunpowder is held to be. This test is, however, decidedly
fallacious, because the gunpowder may be of low specific gravity, or it
may have become friable from age and other causes.
Whales are shot with gunpowder proportioned to the weight of the harpoon
required to kill them. Duck guns of the largest calibre are
comparatively useless unless the gunpowder used is granulated according
to the weight of the projectile; and the same law holds in regard to the
most “mammoth” engine yet to be devised by the mind of man.
Gun-cotton has been before the world for some years, but, except as a
curiosity, it has attracted little public attention; neither has it
gained any reputation as a projectile force. It may be prepared by
steeping cotton wool for a few minutes in a mixture of nitric and
sulphuric acids, thoroughly washing, and then drying at a very gentle
heat. It consists chemically of the essential elements of gunpowder:
viz. carbon, nitrogen, and oxygen; but, in addition, it contains another
highly elastic gas, hydrogen. The carbon in the fibres of the wool
presents to the action of flame a most extended surface in a small
space, and the result is an explosion approaching as nearly as possible
to the instantaneous: in consequence of its rapid ignition it produces a
violent kick; sufficient time is not given to put heavy bodies in
motion, hence it cannot be usefully employed as a projectile agent. No
one who values his limbs should trifle with it, for fearful accidents
have resulted from its exposure to the heat of the sun, and other very
simple causes.
There is an instrument used by some sportsmen, and strongly recommended
by many gunmakers, for testing the strength of different kinds of
gunpowder. It consists of a chamber closed by a spring, and fired like
an ordinary pistol. When the powder explodes the spring is forced
forward, and moves an index round a graduated circle; the more quickly
the powder explodes the farther does it lift the spring; hence this is a
measure of quickness of fire, but not of expellant force; and from the
observations which have been made on gunpowder, it must be evident to
any one who has paid the least attention to the subject, that this
instrument is utterly useless.
An instrument to test the comparative strength of different kinds of
gunpowder is yet a desideratum in projectile science; and we cannot
doubt that such an instrument will be produced, when the importance of
the granulation of gunpowder is more generally known and appreciated.
The charcoal formerly used was made in the common way, by pits, which
must have been seen by almost every one. The method is now to _distil_
the wood in cast-iron cylinders, extracting the pyroligneous acid, &c.,
by heating them red hot, and allowing all other volatile matter to
evaporate, the charcoal only being retained in the cylinder or retorts;
hence arises the name _cylinder gunpowder_. The best charcoal for
sporting powders is the black dog wood; Government use willow and alder.
Any charcoal does for common powders. Charcoal is ground in the same way
as the nitre. Sulphur is purified simply by fusing, and when in that
state, skimming off the impurities: it is cooled and pulverised in the
same way as the other two ingredients. The three ingredients, after
being carefully weighed in their due proportions, are sifted into a
large trough, and well mixed together by the hands. They are then
conveyed to the powder mill. This is a large circular trough, having a
smooth iron bed, in which two millstones, secured to a horizontal axis,
revolve, traversing each other, and making nine or ten revolutions in a
minute. The powder is mixed with a small quantity of water put on the
bed of the mill, and there kept subject to the pressure of the stones;
and if we calculate the weight of the two millstones at six tons, it
follows that in four or five hours’ incorporation on this bed, it
subjects the ingredients to the action of full 10,000 tons. It is this
long-continued grinding, compounding, and blending together of the
mixture, that alone renders it useful and good. After this intimate
mixing, it is conveyed away in the shape of mill-cake, and firmly
pressed between plates of copper. Bramah’s press has been introduced of
late years--we should say with a good deal of improvement to the powder,
as will be shown hereafter--and by its means the mass is more compressed
and in thinner cakes. It is then broken into small pieces with wooden
mallets, and taken to the corning-house, where it is granulated, “by
putting it into sieves, the bottoms of which are made of bullocks’
hides, prepared like parchment, and perforated with holes about
two-tenths of an inch in diameter; from twenty to thirty of these
sieves are secured to a large frame, moving on an _eccentric_ axis, or
crank, of six inches throw; two pieces of lignum vitæ, six inches in
diameter, and two inches or more in thickness, are placed on the broken
_press-cakes_ in each sieve. The machinery being then put in rapid
motion, the discs of lignum vitæ (called balls) pressing upon the
powder, and striking against the sides of the sieves, force it through
the apertures, in grains of various sizes, on to the floor, from whence
it is removed, and again sifted through finer sieves of wire, to
separate the dust and classify the grain. One man works two sieves at a
time, by turning a handle and eccentric crank; the sieves being fixed to
a frame, which is suspended over a bin by four ropes from the ceiling.”
The grains afterwards undergo a process of _glazing_, by friction
against each other, in barrels containing nearly 200 lbs., making forty
revolutions in a minute, and lasting several hours, according to the
fancy of the purchaser. This part of the business we entirely disagree
with, as injurious to the quick and _certain ignition_. Gunpowder is
finally dried by an artificial temperature of 140° Fahrenheit, which is
suffered gradually to decline. The last process is sifting it clear of
dust, and then packing it in canisters or otherwise.
The utility of the process of granulation results from the impossibility
of firing mealed powder sufficiently simultaneously to effect an
explosion; and also from the fact that gunpowder, in a mass, does not
explode. Fire a solid piece of mill-cake, and it does not flash off like
unto granulated powder, but burns gradually, though with an extreme
fury, until the whole is consumed. This arises from its density, the
compression in the press; it also teaches us one fact, that to be of the
greatest service, the time each grain should occupy in burning should be
proportioned to the size of the gun for which it is required; since it
is clear that the explosion of a heap of gunpowder is but the rapid
combustion of all its parts. This action, as is well known, is so rapid,
even in a large quantity of powder, that it appears to be a sudden and
simultaneous burst of flame; though philosophically and actually it is
not so.
Fine grain, when unconfined, explodes quicker than large, or is sooner
burnt out, and consequently generates more force in the same period of
time; but when it comes to large quantities, its very quickness is
detrimental to its force, by condensing the air around the exterior of
the mass of fluid which thus constrains its bound. In small quantities,
the proportion of condensation is not so apparent, and hence the reason
why greater velocities can be obtained with small arms than with cannon.
There exists a diversity of opinion in regard to the strength or
projectile force of gunpowder. Dr. Ure remarks--“If we inquire how the
maximum gaseous volume is to be produced from the chemical reaction of
the elements of nitre on charcoal and sulphur, we shall find it to be by
the generation of carbonic oxide and sulphurous acid, with the
disengagement of nitrogen. This will lead us to the following
proportions of these constituents:
Hydrogen 1. Per Cent.
1 prime equivalent of nitre 102 75·00
1 „ „ sulphur 16 11·77
3 „ „ charcoal 18 13·23
--- ------
136 100·00
“The nitre contains five primes of oxygen, of which three combining with
the three of charcoal, will furnish three of carbonic oxide gas, while
the remaining two will convert the one prime of sulphur into sulphurous
acid gas. The single prime of nitrogen is therefore, in this view,
disengaged alone.
“The gaseous volume, in this supposition, evolved from 136 grains of
gunpowder, equivalent in bulk to 75-1/2 grains of water, or to
three-tenths of a cubic inch, will be, at the atmospheric temperature,
as follows:--
Grains. Cubic Inches.
Carbonic oxide 42 141·6
Sulphurous acid 32 47·2
Nitrogen 14 47·4
-----
236·2
being an expansion of one volume into 787·3. But as the temperature of
the gases, at the instant of their combustive formation, must be
incandescent, this volume may be safely estimated at three times the
above amount, or considerably upwards of 2,000 times the bulk of the
explosive solid.
“It is obvious that the more sulphur, the more sulphurous acid will be
generated, and the less forcibly explosive will be the gunpowder. This
was confirmed by the experiments at Essonne, where the gunpowder that
contained twelve of sulphur, twelve of charcoal, in 100 parts, did not
throw the proof shell so far as that which contained only nine of
sulphur and fifteen of charcoal. The conservative property is, however,
of so much importance for humid climates and our remote colonies, that
it justifies a slight sacrifice of strength.
“When in a state of explosion, the volume,” Dr. Hutton calculates, “is
at least increased eight times, and hence its immense power. The
pressure exerted, if in a state of confinement, will depend on the
dimensions of the vessel containing it; so that it would be no difficult
undertaking to obtain any pressure above that of the atmosphere, up, we
may fearlessly say, to the enormous amount of 4,000 lbs. per square
inch.”
The same quantity of gunpowder subjected to a variety of experimental
tests, differs materially in its results; at the same time it is only by
such a method that we can arrive at the relative strength or power which
it possesses. Dr. Hutton, whose authority in all mathematical
calculations is very high, and whose opinions and judgment in matters of
this nature ought not to be unthinkingly controverted, states 2,000 feet
per second (with cannon) as the highest velocity which any projectile
had attained, at the time of his writing, which had gunpowder for its
propellant power. A much greater velocity is now given in all guns
fired at high elevations. “Monks’” gun attained a velocity of 2,400 feet
in the first second of its flight, and this is now exceeded by rifled
cannon.
This advantage does not arise, in our opinion, so much from the superior
quality of the gunpowder, as from the improvements which have taken
place in the manner of applying it. For instance, where experiments are
conducted, as was the case with Dr. Hutton, with moving _eprouvettes_, a
certain loss is sustained, in the same degree as the instrument is made
to recoil from its original position; therefore, by restraining the
recoil, an increase of momentum is given to the projectile, to the same
extent as had been exerted upon the _eprouvette_, or cannon, in driving
it several feet backward; and instead of dividing the force thus
acquired between the shot and the gun, by having the latter firmly fixed
and the recoil destroyed, the whole power is exerted upon the former,
and its velocity accelerated in the same proportion.
Gunpowder, though astonishing in its effect, and tremendous in power,
may nevertheless be controlled within a limited sphere, and bounds put
upon its destructive energy. The following curious experiment, first
tried at Woolwich on a small scale, has since been carried out to a
great extent. Screw into each end of the breech part of a gun-barrel a
well-fitted plug; drill a communication, and put in a nipple; having
filled the barrel with powder, screw in the breech, and fire a cap on
it, and the explosive fluid will escape by the small orifice like steam
from a pipe. If the barrel be good, it may safely be held in the hand,
merely using a towel to protect the hand from the heat the barrel
absorbs. We have done it repeatedly with no inconvenience, and even
carried this experiment much further; firing two ounces of the best
powder in a barrel of good quality (though not in the hand) yet the
barrel did not receive any violent motion by which it could be inferred
that it might not be done with safety.
We have before observed, that, with very short guns, fine gunpowder
produces the greatest result, inasmuch as there is no greater column of
air in the barrel than the explosive fluid is equal to _displace_; or,
in other words, the charge leaving the muzzle of the gun at the very
moment when the explosive force is strongest, all the power is thus
obtained of which it is capable; but if used in a longer barrel, and the
fluid has obtained its greatest power when the charge has twelve inches
of the barrel still to travel, the column of compressed air yet
remaining in the muzzle of the barrel, exerts a resisting influence, in
proportion to its density, upon the charge, and creates a dangerous and
unpleasant recoil.
If a cartridge be placed in the centre of an open barrel eight feet in
length, having a bullet abutting at each end large enough to fill the
barrel, and a touch-hole is drilled as near the centre of the cartridge
as possible, when it is fired, the balls will certainly be discharged
from the barrel, but with a very small degree of force: in fact, merely
driven out. With the same instrument, vary the experiment: place in it a
cartridge charged with one ball, three feet from the muzzle, leaving a
column of air five feet in length to act against the explosive force of
the gunpowder, and the ball will be driven one hundred yards with
considerable force. Again, let a third cartridge be introduced similar
to the last, two feet from the muzzle, increasing the column of air to
six feet; and the result, in distance and velocity, will nearly double
what has been obtained by the last experiment; tending to prove that air
thus forced back upon itself obtains a density, and consequent resisting
influence, nearly equal to a well-screwed breech. In order to test this
principle further, I put into the same tube a double charge of
gunpowder, merely backed by a wadding, two feet from the muzzle, and
then rammed down four balls as tight as possible into the short portion;
in discharging it, the tube was burst immediately in rear of the charge.
In another experiment, I took a common musket barrel, having a plug of
iron firmly fixed into the muzzle; the breech being unscrewed, and a
ball introduced one-tenth of an inch less in diameter than the bore of
the barrel, together with one drachm of gunpowder, I then fired the
gunpowder, and the explosive matter escaped by the touch-hole. On
examination, it was found that the ball was flattened to the extent of
one-third of its sphere. The charge for the next experiment was
increased to two drachms; when the ball in the discharge struck the
muzzle very slightly, altering its shape in the least conceivable
degree. The charge was next increased to three drachms, and the ball
was extracted without any perceptible defect. In the fourth trial,
another drachm was added, with which the effect was greater than the
tube was able to resist; it was in consequence burst, about three inches
from the muzzle.
From this I infer that, in the first trial, the velocity of the ball was
not so great, but that the air escaped past it, by what is technically
called the windage, allowing it to strike the plug at the end of the
barrel with sufficient force to alter the shape of the lead in the
manner described. The second trial gave an increased velocity; the
opposing forces being so nearly balanced that the ball scarcely reached
the end of the barrel, and was very little injured. In the third trial
the velocity became so great, and the air was condensed to such an
extent, that the ball struck upon a cushion-like surface so highly
elastic that it was extracted without the least injury to its shape. The
last charge was too powerful, inasmuch as the lateral pressure of
compressed air rent the tube asunder.
The one great cause of this and other barrels bursting, arises from the
velocity becoming too great, and thus driving back the air upon itself,
until the mutual repulsion of the particles forms an almost impenetrable
barrier, exerting a lateral pressure on the barrel, and resisting the
passage of the elastic fluid. To make the explanation plain; supposing
that the charge had condensed the air for the distance of three or four
inches immediately preceding it, and then come to rest, the waves of
vibration, travelling at the rate of 1,300 feet per second, would
communicate to the remainder of the column the same pressure, and an
equilibrium would take place. But this not being the case, and the air
becoming still more highly compressed by the velocity not decreasing but
increasing, the lateral pressure becomes greater than the fibres of the
iron are able to withstand, and consequently the barrel is burst. Many
accidents arise from this cause solely, and without any blame being
attached to either the maker or user of the gun. While on this subject,
we may remark that this is the more likely, inasmuch as the powder with
which barrels are proved is not the strongest, and is also of a large
grain; so that it is quite within the range of probability that a barrel
may, and it does often, stand proof, and yet burst when it comes to be
used with extremely fine-grained strong powder; as it is quite clear
that a high velocity must create danger.
To pursue the subject still further: in order to procure conclusive
evidence in support of this argument, I had a tube of iron manufactured,
sufficiently good in quality to bear an enormous pressure; it was three
feet in length, with a bore large enough to admit an ounce ball, and the
sides of the arch were full a quarter of an inch in thickness. A piece
of steel, one inch in length, was then turned of a size to fit the bore
well, but not so tight as to prevent its free action: this I called a
piston. From the centre of the tube to the muzzle, were drilled, on all
sides, a number of small holes, a quarter of an inch distant from each
other, in all amounting to sixty-eight; these were fitted with small
pieces of steel needles, hardened, projecting into the interior of the
tube a quarter of an inch, so that the piston, in its upward movement,
should strike these pins, and thus enable me to judge how far it was
driven by each experiment. Each end of the tube was then fitted with a
breech, firmly screwed in; the upper one having a flat internal surface,
the lower one, where ignition was to be communicated, being a conical or
patent breech. This machine I termed an explosion metre; and it answered
its purpose. With two drachms of the best canister gunpowder, the piston
was propelled nineteen inches along the tube; breaking eight pins. The
same quantity of the fine diamond grain reached only eighteen inches, or
four pins. No. 3 grain, of both Laurence’s and Pigou and Wilks’
manufacture, reached twenty-four inches, or twenty-eight pins. A very
superior powder, containing in one grain five of diamond, four of
canister, and two of the above makers’ No. 2, reached twenty-seven
inches, and broke forty pins. In each of these experiments the greatest
accuracy was observed, in preparing the metre as well as in weighing the
charge.
These facts go far to prove that, in all uses of gunpowder, the grain
should be of a size proportioned to the length and bore of the gun; for
if we have not an accelerating force to overcome the increasing
resistance of the compressed column of air in the barrel, there is great
danger that the gun may be burst, and probably be productive of great
mischief; whilst a judicious application of the extraordinary power thus
placed at our disposal, may be alike conducive to our safety and our
pleasure. A musket ball can be driven through an half-inch boiler plate;
but this can only be accomplished by using as much powder as will
generate a gradually, though rapidly, increasing power, until the ball
has passed the limits of the tube.
Nitre is not the only salt which has been employed in the manufacture of
gunpowder. Its quantity or proportion in the mixture has been lessened,
and the deficiency supplied by another elementary combination; namely,
by the chlorate of potassa.
The French succeeded in making powder of which potassa forms one of the
component parts, and they say it ranges the projectile double the
distance; but this is doubtful. The proportions of the mixture are
nitrate of potash twenty-five parts, chlorate of potassa forty-five,
sulphur fifteen, charcoal seven and a half, and lycopodium seven and a
half parts. In the year 1809, a similar kind of powder was proposed to
the English Government, by a person of the name of Parr; but its
introduction was very properly opposed by Sir William Congreve, on
account of the danger attending its use, and also from the fact that
there was no piece of ordnance in the service able to withstand its
effects. The proportions were, chlorate of potassa six parts, fine
charcoal one part, sulphur one part. These ingredients to be _carefully_
mixed together and granulated. The above mixture was laid aside, not
only from the want of power to restrain its effects, but because it was
useless, from the very extreme rapidity of its explosion: it forms the
atmospheric air into a wall of adamant, by the condensation confining it
to a comparatively small space; it becomes lightning--an electric fluid,
which, from its very intensity, cannot displace any great mass of air.
Neither can any advantage arise from any greater velocity in projectile
force, except we can obtain that by a graduated scale; for masses
cannot, from a state of rest, be put in extreme motion instantaneously:
philosophy teaches us, and experience makes it evident, that a portion
of time must be occupied, however short that may be. All motion is
gradual, and cannot be obtained otherwise; and hence the fact, that
lightning conveyed into a tube filled with projectiles would not drive
them out: it would not project them, but the blow would break them in
pieces. So is it with this mixture; it is useless from its very rapidity
of ignition. We have shown that even fine grain gunpowder is too quick,
and that its quickness destroys its power; how much more so is the
other: and what would it avail us, with these disadvantages.
A writer mentions what he conceives to be a curious fact: he says, “If a
train of gunpowder be crossed at right angles by a train of fulminating
mercury, laid on a sheet of paper on a table, and the gunpowder lighted
by a red hot wire, the flame will run on until it meets the cross train
of fulminating mercury, when the inflammation of the latter will be so
instantaneous as to cut off the connection with the continuous train of
gunpowder, leaving one half of the train unignited:” and again, “If the
fulminating powder be lighted first, it will go straight on, and pass
through the train of gunpowder so rapidly as not to inflame it at all.”
True; and the cause is quite apparent: the rapidity of combustion
condenses the air so quickly, as to remove the grains of gunpowder
liable to come in contact with the flame, and to form the condensed air
into a line of demarcation: for heat cannot be taken up by the air
quicker than the atmosphere will convey sound; and before the heat can
evaporate the explosion is over, and is consequently noiseless.
In all mining operations: in the quarrying of stone, the destruction of
sunken rocks, or in any other operations where it is desirable to detach
large masses, the use of gunpowder is indispensable; not only because it
decreases manual exertion but also because it can be used under
circumstances and in situations unapproachable by other means. It
becomes, therefore, a consideration for the miner what kind is best
suited for the purpose; the finest grained powder is useless as is well
known: it is also more expensive; but its principal defect arises from
its quickness of combustion. Masses cannot be detached without first
putting the whole in motion; and as this cannot be done in a very short
time, it is necessary to prolong the explosion, so that the wave of
vibration may have time to travel throughout the whole of the mass acted
upon; and a repetition of these waves is necessary before any mass can
move. Now, to obtain this, it is necessary that matter be so
incorporated with the powder as to prolong that explosion; bituminous
substances might be applied with effect, for their slow burning would
keep the heat necessary to hold the permanent gases at their utmost
stretch of expansion.
It is obvious, from the extremely high character English sporting
gunpowder has obtained all over the world, that considerable improvement
must have been effected by the private manufacturers, either in the
purification or manipulation of ingredients; indeed the unwearied care
bestowed on this point by several of our best makers is beyond all
praise. To explain the various methods, or otherwise enlarge upon this
point, would be injurious to individual skill and enterprise, and be the
means of imparting knowledge to those who have not ability to invent,
but who gather from the brains of others. The French set great value on
the “Poudre de Chasse” of England. It is rather singular that we should
excel those who pride themselves so much on their chemical knowledge;
but, as before remarked, it is certain that the intimate incorporation
of the ingredients is of more importance than the chemical proportions.
All military and naval gunpowder is not manufactured of the greatest
strength that can be acquired “_at the Government mills_;” a sample is
furnished to each contractor with each contract, and to this strength he
is limited.
The fame of our English gunpowder makers is patent to all the world,
and, where skill is equal, to name one rather than another would be
invidious; though we must not lose sight of the facts herein
established. “Granulation,” properly understood, is an equivalent point
to either chemical or mechanical knowledge and manipulation in gunpowder
manufacture. Great anxiety to meet the wishes of the sporting world on
this point, and to advance with the age, has been aroused; and specimens
have been kindly furnished to me, not by one, but by all the following
celebrated makers: Messrs. Pigou and Wilks, Curtis and Harvey, Lawrence
and Son, John Hall and Son; and I have received also a very excellent
specimen from the Scotch mills.
Gunpowder of five sizes of granulation, on the basis before alluded to:
namely, No. 2, containing two quantities of No. 1, and No. 3, three, and
so on in progression; but it is imperative that all the various sizes be
produced from the same mill cake, or be otherwise of the same
condensation or specific gravity, and in all experiments of comparison,
equal weights are a “sine quâ non,” otherwise the comparison will be
futile; as measure is, for these very obvious reasons, inapplicable in
comparative tests. When these points are carefully attained, increased
power of killing, “decreased recoil,” and much greater safety, will be
the important benefits which the gunpowder manufacturers will confer on
every one using a gun.