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[Illustration: PLATE 1. (Figs. 1 to 16)]
A
MANUAL
OF
PYROTECHNY;
OR,
A FAMILIAR SYSTEM
OF
Recreative Fire-Works.
BY G. W. MORTIMER.
Admotam rapiunt vivacia sulfura flammam.
OVID.
LONDON:
PRINTED FOR W. SIMPKIN & R. MARSHALL,
STATIONERS’ HALL COURT, LUDGATE STREET.
MDCCCXXIV.
W. TYLER, PRINTER, 5, BRIDGEWATER SQUARE.
PREFACE.
The Introduction prefixed to the following little Manual supersedes
the necessity of an extended Preface, and leaves little more to be
mentioned than the design and occasion of the work.
The design of it is to be a useful assistant to those who are fond
of a rational and scientific amusement, and the occasion of it
arises from the great scarcity and general difficulty of procuring
any work on the subject; none having appeared worthy of notice since
that published by Lieutenant Robert Jones, in 1760, and those by the
French Artists mentioned in our Introduction.
In didactic particulars the Author has occasionally availed himself
of the language of the best writers, where such has been corroborated
by subsequent experience.
Perspicuity has been a particular object through the work, and when
technical terms have been used they are generally followed by
familiar explications, and the Author feels assured that the whole
will be found perfectly intelligible to every reader. To experienced
Pyrotechnists this little work cannot be expected to afford much
additional information, yet to them it may contain some little
particulars not known to them before, which from their practical
utility it is hoped will prove acceptable.
The Author publishes this little work, with the desire that it may
prove a useful assistant to those who are unacquainted with the
principles of the art on which it treats. If in any way it should
contribute to this purpose, an apology for obtruding it upon the
Public will certainly be unnecessary.
_January 1st, 1824._
CONTENTS.
Page
Introduction 1
SECTION I.
History and description of Gunpowder 10
SECTION II.
Materials 29
Nitre ibid.
Sulphur 32
To purify Sulphur 34
Charcoal ibid.
Steel-dust 35
To prepare Iron-sand 37
Second method ibid.
Oil of Camphor 40
Benzoin ibid.
SECTION III.
Apparatus 42
Grinding Machines 43
Another method of Grinding 44
Method of Mixing the Ingredients 45
SECTION IV.
Description and Variety of Fire-works 47
Touch-paper 48
To make Touch-paper ibid.
Quick-match 49
To make Quick-matches; and composition for ditto 50
Port-Fires 51
Compositions for ditto 52
Port-fires for Illuminations 53
Leaders, or Pipes of Communication ibid.
Application of ditto 54
SECTION V.
Of single Fire-works 57
Serpents ibid.
Crackers 59
Pin wheels 61
Stars 63
Strung Stars 64
Tailed Stars 65
Driven Stars ibid.
Rolled Stars 6
Sparks 68
Another method of making ditto 69
Marroons ibid.
Construction 70
Saucissons ibid.
Batteries of Marroons, &c. 71
Gerbes 72
Small Gerbes 75
Roman Candles 76
Chinese Fire 79
Composition for ditto, Red and White ibid.
SECTION VI.
Rockets 81
Sky Rockets 83
Dimensions of Rockets 88
Calibre and Weight of Rockets 89
Calibre of Moulds 90
Remarks on the foregoing Tables 91
Preparing the Cartridges 93
Filling and Ramming the Cases 96
Directions for ditto 97
Preparing and fixing the pots to the Heads of Rockets 101
Table for the Length and Proportion of Rods 105
Tables of Composition for Rockets 106
To cause a Rocket to ascend in a Spiral form 109
Towering Rockets 110
Honorary Rockets 111
Caduceus Rockets 112
Signal Rockets 113
Table Rockets 115
Scrolls for Rockets 116
Courantines, or Line Rockets 117
Revolving Courantines 121
To represent by Rockets various forms in the air 122
To cause a Rocket to form an arc in rising 128
To fire Rockets without Rods 124
Theory of the flight of Rockets 125
SECTION VII.
Tables of various compositions 130
SECTION VIII.
Compound Fire-Works 139
Girandole chests of Serpents ibid.
Girandole chests of Rockets 141
Pots des Brins 142
Jets of Fire 143
Chinese Fountain 145
Pyramid of Flower Pots 146
Wheels 149
Ditto single Horizontal 150
Ditto Plural 152
Wheels Spiral 152
Ditto Ditto Illuminated 153
Ditto Balloon 154
Ditto Ground 155
Ditto Horizontal changed to a Vertical 156
Ditto Vertical Scroll 158
Ditto remarks on ibid.
Fir tree, to represent 159
Yew tree of Brilliant Fire 160
Fixed Fire Globes 161
Globes which leap or roll on the ground ibid.
Moon and seven Stars 164
Suns, fixed and moveable 165
Composition for representing Animals and other devices in fire 168
Aquatic fire-works ibid.
Fire fountain for the water 170
Conclusion 172
[Illustration: (Figs. 17 to 29)]
Introduction.
The term _Pyrotechny_ is derived from _pyr_ and _techny_, the two
Greek words for FIRE and ART; or it is the art of employing fire for
purposes of utility or pleasure. The term has been applied by some
writers to the use and structure of fire-arms, and Artillery employed
in the art of warfare; but in the present publication, we shall take
a different view of the subject; for we can see no amusement in the
motion of a bullet, which decimates so many of our fellow-creatures,
nor in the action of a bomb-shell, that carries with it more dreadful
devastations.
We shall confine ourselves in this Work to a more pleasing
application of fire, and endeavour to give plain and efficient
rules for the _safe_ management of that element, and for the making,
by means of gunpowder, and other inflammable substances, various
compositions, agreeable to the eye, both by their form and splendor,
and to describe every principal article and instrument made use of in
these pleasing operations.
On the other hand, our Work does not pretend to dictate an _original_
set of rules and receipts, for those who term themselves _Artists
in Fire-works_, whose exclusive business it is to manufacture the
different articles on which it treats; to those, it is expected it
will yield but little instruction; but, to the sciolistic Tyro in
the Art, it is intended (as its title expresses) to be a _Manual
of Pyrotechny_, and to treat of fire-works as objects of rational
amusement; to describe in a perspicuous manner the materials and
apparatus made use of in their construction; and to select such
examples of their particular combinations, as are calculated rather
for private diversion than public exhibition. The directions herein
given (if strictly attended to) will enable youth to gratify
their taste for this species of recreation at a comparatively
small expense, and at the same time will guard them against those
accidents which often arise to the ignorant, in firing the larger
works purchased from the makers; and throughout the whole it will
strictly observe a principle of economy, the neglect of which has so
frequently retarded the operations of genius.
In regard to the origin of Pyrotechny, our knowledge is very
limited. The Chinese are said to have been the first people who had
any practical knowledge of it, or brought the art to any degree of
perfection; with them the use of fire-works is said to have been
very general, long before they were known in European countries;
and from accounts given of some recent exhibitions at Pekin, it
should seem that they have attained to a degree of perfection not
surpassed by any of our modern artists: Mr. Barrow, in his “Travels
in China” gives, from the Journal of Lord Macartney, the following
description of one of their exhibitions: “The fire-works, in some
particulars,” says he, “exceeded any thing of the kind I had ever
seen. In grandeur, magnificence, and variety, they were, I own,
inferior to the Chinese fire-works we had seen at Batavia, but
infinitely superior in point of novelty, neatness, and ingenuity
of contrivance. One piece of machinery I greatly admired: a green
chest, five feet square, was hoisted up by a pulley fifty or sixty
feet from the ground, the bottom of which was so contrived as then
suddenly to fall out, and make way for twenty or thirty strings of
lanterns, inclosed in a box, to descend from it, unfolding themselves
from one another by degrees, so as at last, to form a collection of
full five hundred, each having a light of a beautifully coloured
flame burning brightly within it. This devolution and development of
lanterns were several times repeated, and at every time exhibiting a
difference of colour and figure. On each side was a correspondence
of smaller boxes, which opened in like manner as the other, and let
down an immense net-work of fire, with divisions and compartments of
various forms and dimensions, round and square, hexagons, octagons,
&c. which shone like the brightest burnished copper, and flashed
like prismatic lightnings, with every impulse of the wind. The
whole concluded with a volcano, or general explosion and discharge
of suns and stars, squibs, crackers, rockets, and grenadœs, which
involved the gardens for an hour in a cloud of intolerable smoke.”
The diversity of colour, with which the Chinese have the secret
of clothing their fire, seems one of the chief merits of their
“Pyrotechny;” and which alone would set them upon an equal footing
with the Europeans. It is to them, no doubt, that we are indebted
for the discovery of that beautiful composition, which is still
known by the name of the “Chinese fire:” and to them we are likewise
indebted, for the method of representing with fire, that pleasing
and perpetual variety of figures, which (when judiciously arranged)
seem to emulate in splendour those endless beauties, which adorn our
celestial hemisphere. In Europe, the Florentines are said to have
been the first people that gained a knowledge of the invention, and,
we have reason to think it was not long after the discovery of the
use of gunpowder and fire-arms, about the end of the thirteenth, or
beginning of the fourteenth century; we say the _use_ of gunpowder,
or application of it to fire-arms, for we believe the discovery
of it to be of much earlier date, than what is generally given to
it: and, whether the invention of the art of fire-works is not
coeval with that of gunpowder, is a question not over-burthened
with improbability. The French have published several treatises
on Pyrotechny, such as the “_Traité des Feux d’Artifice pour le
spectacle et pour la Guerre_,” by Perrinet d’Orval. The _Manuel
d’Artificier_, by Father d’Incarville, and several others of the like
nature: in some of which, they attach to the Chinese a _very_ early
knowledge of the art, and consequently the composition of gunpowder,
or at least the effects of a similar combination, was not entirely
unknown to them. But as the French gained their knowledge of the
art from the Italians, they may probably be in an error respecting
its invention: whether they are or not, it will have but a negative
effect on the present Work. Tracing its progress to England, we
shall endeavour to give as good a delineation of the state in which
it now exists, as the nature of our Work will admit; supposing it to
be much nearer perfection than when in its earlier stages, for we
believe the English import nothing but what they improve.
An art which furnishes such an extensive field for amusement, reduced
to plain and simple rules, digested in a familiar manner, (which the
most limited capacities will be able to understand,) cannot fail to
be entertaining to every admirer of scientific amusement.
It has been regretted by many that no publication of a like nature
is now extant; and a celebrated writer, long known to the popular
reader, has even said, that “the English have no respectable work on
the subject.”
How far the present will supply such a desideratum must be left
for the candid reader to determine. The Author would wish it to
be understood, that although he has conducted some part of his
Work upon mathematical principles, it is not intended as a perfect
philosophical work on the subject, but as an attempt to embody into
one small volume, all that has hitherto been written on the subject;
and if from which, the Pyrotechnic Tyro receive any assistance for
the attainment of an Art, which has for its object such an endless
source of entertainment, the Author’s purpose will be positively
realized.
Though very much protracted, we cannot close our Introduction without
observing, that few spectacles are more beautiful or more calculated
for entertainment, than a well-conducted display of fire-works, in
which are exhibited such various bodies, so brilliantly illuminated,
and arranged in the most variegated forms: sometimes producing
surprising and unexpected manations, moving with velocity through the
air, throwing out innumerable sparks or blazing balls, which fly off
into the infinity of space: others suddenly exploding, scatter abroad
luminous fragments of fire, which are trajected with the most speedy
trepidation: and again, others are revolving on a quiescent centre,
and by their revolutions produce the most beautiful circles of fire,
which seem to vie with each other in their emanations of splendour
and light.
Such is a faint delineation of the various effects which are
producible by fire, and for which we shall endeavour to give every
requisite instruction; and for preparing the most pleasing garbs, in
which this element may be presented.
MANUAL, &c.
SECTION I.
OF GUNPOWDER.
Before we enter into the practical part of Pyrotechny, we deem it
consistent with the nature of our Work to give an ample description
of the materials made use of; for we do not take it for granted that
all our readers are _chemists_, or that they are sufficiently versed
in that science to render such description unnecessary. But before
the principles of the art can be well understood, or successfully
applied, it is proper that the artist should possess a portion of
_chemical_ and _mechanical_ knowledge; the first will teach him to
select his materials with judgment, to free them from impurities, and
combine them in the proportions most suitable for each particular
purpose; and the latter will assist him in constructing his different
pieces so as to produce the desired effect with the least loss of
time and force. The _mechanical apparatus_ we shall defer describing
till they come immediately under hand, and such protraction we think
will be conducive to a better understanding of their utility: and,
in some other Section, we shall teach him to calculate the direction
which the flying fire-works (from their principles of construction)
are to move, and the velocity with which they are to proceed.
Gunpowder is the principal ingredient made use of in Pyrotechny; and,
being of itself a compound, we shall make it the first object of
description, and endeavour to point out the cause of every property
it possesses.
The invention of it is ascribed, by Polydore Virgil, to a chemist,
who accidentally put some of the composition, viz. nitre, sulphur,
and charcoal into a mortar, and covered it with a stone, when it
happened to take fire, and, what was a natural (though unexpected)
consequence of such combination, it shattered the stone to pieces.
Thevet says, the person here spoken of was a monk of Fribourg, named
Constantine Anelzen; but Belleforet, and other authors, with more
probability, suppose him to be Bartholdus Schwartz, or the Black, who
discovered it, as some say, about the year 1320; and the first use
of it is ascribed to the Venetians in the year 1380, during the war
with the Genoese; and it is said to have first been employed in a
place anciently called Fossa Clodia, now Chioggia, against Lawrence
de Medicis; and that all Italy made complaints against it, as a
manifest contravention of fair warfare.
But this account is contradicted, and Gunpowder shewn to be of an
earlier era, for the Moors, when they were besieged in 1343 by
Alphonsus XI. King of Castile, are said to have discharged a sort of
iron mortars upon them, which made a noise like thunder; and this
assertion is seconded by what Don Pedro, bishop of Leon, relates
of King Alphonsus, who reduced Toledo, viz. “that in a sea-combat
between the King of Tunis, and the Moorish King of Seville, about
four hundred and fifty years ago, those of Tunis had certain iron
tubes or barrels, wherewith they threw thunder-bolts of fire.”
Farther, it appears that our Roger Bacon knew of Gunpowder near a
hundred years before Schwartz was born. That excellent friar tells
us, in his treatise, “_De Secretis Operibus Artis & Naturæ, & de
Nullitate Magiæ_,” that from salt-petre, and other ingredients,
we are able to make a fire that shall burn at what distance we
please; and the writer of the life of Friar Bacon says, that Bacon
himself has divulged the secret of this composition in a cypher,
by transposing the letters of the two words in chap. xi. of the
above-cited treatise, where it is thus expressed; “sed tamen salis
petræ _lura mope can ubre_, (i. e. carbonum pulvere) et sulphuris;
et sic facies tonitrum & corruscationem, si scias artificium:” and
from hence Bacon’s biographer apprehends the words _carbonum pulvere_
were transferred to the sixth chapter of Dr. Longbain’s MS. In this
same chapter Bacon expressly says, that sounds like thunder, and
coruscations, may be formed in the air, much more horrible than those
that happen naturally. He adds, that there are many ways of doing
this, by which a city or an army might be destroyed; and he supposes
that, by an artifice of this kind, Gideon defeated the Midianites
with only three hundred men, (Judges, chap. 7th.) There is only
another passage to the same purpose, in his treatise “De Scientia
Experimentalia:” see Dr. Jebb’s edition of the Opus Magus, p. 474.
Mr. Robins apprehends (see the preface to his Tracts,) that Bacon
describes Gunpowder, not as a new composition first proposed by
himself, but as the application of an old one to military purposes,
and that it was known long before this time.
Dr. Jebb, in his preface to the above-cited work, describes two
kinds of fire-works; one for flying, inclosed in a case or cartouche,
made long and slender, and filled with the composition closely
rammed, like our modern rocket, and the other thick and short,
strongly tied at both ends, and half filled, resembling our cracker;
and the composition which he prescribes for both, is two pounds of
charcoal, one pound of sulphur, and six pounds of salt-petre, well
powdered and mixed together in a stone mortar.
Mr. Dutens in his “Inquiry into the Origin of the discoveries
attributed to the moderns,” carries the antiquity of Gunpowder
much higher; and refers to the accounts given by Virgil, Hyginus,
Eustathius, Valerius Flaccus, and many other writers of the same date.
To close this tedious detail, we will mention one more work, which
seems to confirm the antiquity of this composition, viz. the “Code
of Gentoo Laws,” 1776; in the preface of which it is asserted, that
Gunpowder was known to the inhabitants of Hindostan, far beyond all
periods of investigation.
Having said thus much concerning the history and antiquity of this
wonderful composition, it remains for us to describe the method by
which it is now manufactured: but to retain that _gradatum_, or
progressive order, with which we commenced our Work, it is necessary
that we first describe the ingredients of which it is composed; for
it is only by a knowledge of the parts of any composition, that we
can gain a good understanding of the properties of the whole.
There are only three ingredients that enter into the composition of
Gunpowder; these are Salt-petre, Sulphur, and Charcoal. The first is
a combination of Nitric Acid[1] and Potash,[2] and is better known
in modern chemistry by the name of Nitrate of Potash. The second
is a substance very well known, from the inflammable properties it
possesses; it is found alone, or combined with other bodies, in
various situations; in volcanic productions it is found almost in its
last degree of purity: it is found also, in the state of sulphuric
acid; that is to say, combined with oxygen: it is found in this
state in argil,[3] gypsum,[4] &c. and it may be likewise extracted
from vegetable substances and animal matter. The third and last, is
an article so well known in commerce, that it is almost needless to
describe it; we shall therefore only observe, that the Charcoal found
to be best for the composition of Gunpowder, is that made from the
alder, willow, or black dog-wood.
This powerful composition is a mixture of these three ingredients,
combined in the following proportions: for each 100 parts of
Gunpowder, salt-petre 75 parts, sulphur 10, and charcoal 15. In some
countries, the proportions are somewhat different; but this is the
combination made use of by most of the English manufacturers.
The salt-petre is either that imported from the East Indies, or that
which has been extracted from damaged Gunpowder. It is refined by
solution, filtration, evaporation, and crystallization; after which
it is fused, taking care that too much heat is not employed, or there
is danger of decomposing the nitre.
The sulphur used is that which is imported from Sicily, and is
refined by melting and skimming; the most impure is refined by
sublimation.
The charcoal is made in the following manner. The wood is first cut
into pieces of about nine inches in length, and put into an iron
cylinder placed horizontally. The front aperture of the cylinder is
then closely stopped: at the other end there are pipes connected with
casks. Fire being made under the cylinder, the pyro-ligneous acid[5]
comes over. The gas escapes, and the acid liquor is collected in the
casks: the fire is kept up till no more gas or liquid comes over, and
the carbon[6] remains in the cylinder.
The three ingredients being properly prepared, are ready for
manufacturing. They are first separately ground into a fine powder,
then mixed in the proper proportions, and afterwards committed to
the mill for the purpose of incorporating their component parts. The
powder-mill is a slight wooden building, with a boarded roof, so
that in case of accidental explosions, the roof may fly off without
difficulty, and in the least injurious direction, and thus be the
means of preserving the other parts of the building.
The operative parts of the mill consist of two stones placed
vertically, and running on another placed horizontally, which is
called the bed-stone, or trough. On this bed-stone, about forty or
fifty pounds of the composition are spread out, and moistened with
water till reduced to about the consistency of a very stiff paste:
after the stone-runners have made the proper revolutions over it,
which requires about eight hours continued action of the mill, which
is worked sometimes by horses, and sometimes by water, it is then
taken from the mill, and sent to the corning-house, to be corned or
grained. Here it is formed into hard lumps, and these are put into
circular sieves, with parchment bottoms, perforated with holes of
different sizes, and fixed in a frame connected with a horizontal
wheel. Each of these sieves is also furnished with a runner or
spheroid of lignum vitæ, which, being set in motion by the action
of the wheels, forces the paste through the holes of the parchment
bottom, forming grains of different sizes. The grains are then
separated from the dust by sieves and reels made for that purpose.
The grains are next hardened, and the rougher edges are taken off
by shaking them for some time in a close reel, moved in a circular
direction with a proper velocity.
When the powder has been corned, dusted, and glazed, it is dried in
the stove-house, where great care should be taken to avoid explosion.
The stove-house is a square apartment, three sides of which are
furnished with shelves or cases, on proper supports, arranged round
the room; and the fourth contains a large cast-iron vessel, called
a “gloom,” which projects into the room, and is heated from the
outside, so that no part of the fuel may touch the powder. For
greater security against sparks by accidental friction, the glooms
are covered with sheet-copper, and are always cool when the powder is
put in or taken out of the room.
Here the grains are thoroughly dried, losing in the process what
remains of the water added to the mixture in the mill, for bringing
it to a working stiffness. A method of drying powder, by steam-pipes
running round and crossing the apartment, has been successfully
tried; and thus the possibility of any injurious accident from
over-heating is prevented. The temperature of the room, when heated
in the common way by a gloom-stove, is always regulated by a
thermometer hung in the door of the stoves.
If Gunpowder is injured by damp in a small degree, it may be
recovered by again drying it in a stove; but if the ingredients
are decomposed, the nitre must be extracted by boiling, filtering,
evaporating, crystallizing, &c. and then, with fresh sulphur and
charcoal, to be re-manufactured.
There are several methods of proving and trying the goodness and
strength of Gunpowder. The following, as common methods, are
frequently made use of. 1, By sight; for if it be too black, it is
too moist, or has too much charcoal in it; so also if rubbed upon
white paper, it blackens it more than good powder does. 2, By touch;
for if in crushing with your finger-ends, the grains break easy, and
turn into dust, without feeling hard, it has too much charcoal in
it; or if in pressing under your fingers upon a smooth, hard board,
some grains feel harder than the rest, or, as it were, dent your
finger-ends, the sulphur is not well mixed with the nitre, and the
powder is bad. And also by burning, in which method, little heaps of
powder are laid on white paper three or four inches asunder, and one
of them fired; which, if the flame ascend rapidly, and with a good
report, leaving the paper free from white spots, and without burning
holes in it, and if sparks fly off and set fire to the adjoining
heaps, the quality of the powder may be safely relied on; but if
otherwise, it is either badly made, or the ingredients are impure.
These are some from among the common methods made use of for this
purpose; but for greater accuracy in determining the relative
strength of Gunpowder, various machines have of late been invented
by men connected with military affairs. That excellent mathematician
and philosopher, C. Hutton, LL.D. F.R.S. and late Professor of
Mathematics in the Royal Military Academy, Woolwich, has constructed
a machine for this purpose, which, for convenience and accuracy,
far surpasses any thing of the kind hitherto invented. It is called
Eprouvette, or a Gunpowder Prover, (for plans and description see
third vol. Hutton’s Tracts, page 153;) and from its possessing so
many peculiar advantages, is now generally used. It consists of
a small cannon, the bore of which is about one inch in diameter,
suspended freely like a pendulum, with the axis in a horizontal
direction. This being charged with the proper quantity of powder,
which is usually about two ounces, and then fired, the gun swings
or recoils backward, and the instrument itself shews the extent of
the first or greatest vibration, which indicates the strength to the
utmost nicety. The whole machine is so simple, easy, and expeditious
in its use, that the weighing of the powder is the greatest part
of the trouble; and it is also so uniform with itself, that the
successive repetitions or firings with the same quantity of the same
kind of powder, hardly ever yield a difference of the hundredth part
from the first vibration.
Having thus given an account of almost every thing necessary to
be known in regard to the process of making and ascertaining the
relative strength of Gunpowder, we shall close this article with a
few observations (which will be selected from the best authorities)
on the physical causes of its inflammation and exploding. When the
several ingredients of Gunpowder are properly prepared, mixed, and
grained, in the manner already described, if the least spark be
struck thereon from a steel and flint, the whole will be immediately
inflamed, and burst out with extreme violence.
The effect is not hard to account for: the charcoal part of the
grains whereon the spark falls, catching fire like tinder, the
sulphur and nitre are ready melted, and the former also breaks into
flame; and at the same time the contiguous grains undergo the same
fate.--Now it is known that salt-petre, when ignited, rarefies to
a prodigious degree. Sir Isaac Newton reasons thus on the subject:
“the charcoal and sulphur in Gunpowder easily take fire, and kindle
the nitre; and the spirit of the nitre, being thereby rarefied into
vapour, rushes out with an explosion much after the manner that the
vapour of water rushes out of an æolipils; the sulphur also, being
volatile, is converted into vapour, and augments the explosion: add,
that the acid vapour of the sulphur, namely, that which distils under
a bell into oil of sulphur, entering violently into the fixed body of
the nitre, lets loose the spirit of the nitre, and excites a greater
fermentation, whereby the heat is farther augmented, and the fixed
body of the nitre is also rarefied into fume; and the explosion is
thereby made more vehement and quick.”
For if salt of tartar be mixed with Gunpowder, and that mixture be
warmed till it take fire, the explosion will be greatly more violent
and quick than that of Gunpowder alone, which cannot proceed from any
other cause than the action of the vapour of Gunpowder upon the salt
of tartar, whereby the salt is rarefied.
The explosion of Gunpowder arises, therefore, from the violent action
whereby all the mixture being quickly and vehemently heated, is
rarefied and converted into fume and vapour; which vapour, by the
violence of that action, becomes so hot as to shine, and appear in
the form of a flame.
Another cause of the effects of Gunpowder, may be owing to the sudden
formation of a quantity of gas, and are consequently greater when
the gas is confined in all directions but one, as in our guns and
cannons. The nitric acid of salt-petre is decomposed, and affords the
gas. The other ingredients dispose it to be easily inflamed, which is
necessary to the decomposition of the acid. Dr. Ingenhousy accounts
for the effect of Gunpowder by observing that nitre yields by heat
a surprising quantity of pure dephlogisticated air, and charcoal
a considerable quantity of inflammable air; the fire employed to
inflame the powder extricates these two airs, and sets fire to them
at the instant of their extrication.
Count Rumford is of opinion that the force of the elastic fluid,
generated in the combustion of Gunpowder, may be satisfactorily
accounted for upon the supposition that its force depends solely on
the elasticity of watery vapour or steam.
M. de la Hire, in the history of the French Academy for 1702,
ascribes all the force and effect of Gunpowder to the spring or
elasticity of the air inclosed in the several grains thereof, and
in the intervals or spaces between the grains, the powder being
kindled sets the springs of so many little parcels of air playing,
and dilates them all at once, whence the effect; the powder itself
only serving to light a fire which may put the air in action, after
which the whole is done by the air alone.
Dr. Hutton seems to differ from the opinion of M. de la Hire, in
regard to the expansion of inflamed gunpowder. Is it, he observes,
occasioned by the air interposed between its grains, or by the
aqueous fluid which enters into the composition of the nitre? We
doubt much (continues he) whether it be the air, as its expansibility
does not seem sufficient to explain the phenomenon; but we know that
water, when converted into vapour by the contact of heat, occupies a
space 14,000 times greater than its original bulk, and that its force
is very considerable.
The same learned author says, that the discovery of the true cause
of the expansive force of fired Gunpowder, is chiefly due to the
English philosophers, and particularly to the learned and ingenious
Mr. Robins. This author apprehends that the force of fired gunpowder
consists in the action of a permanently elastic fluid, suddenly
disengaged from the powder by the combustion, similar in some
respects to common atmospheric air, at least as to elasticity.
He shewed, by satisfactory experiments, that a fluid of this
kind is actually disengaged by firing the powder; and that it is
_permanently_ elastic, or retains its elasticity when cold, the force
of which he measured in this state. He also measured the force of it
when inflamed, by a most ingenious method, and found its strength in
that state to be about a thousand times the strength or elasticity
of common atmospheric air. This, our Doctor observes, is not its
utmost degree of strength, as it is found to increase in its force
when fired in larger quantities than those employed by Mr. Robins;
so much so indeed, that by more accurate experiments, we have found
its force rise as high as 1600 or 1800 times the force of atmospheric
air in its usual state. Much beyond this it is not probable it can
go, nor indeed possible, if there be any truth in the common and
allowed physical principles of mechanics. With an elastic fluid, of
a given force, we infallibly know, or compute the effects it can
produce, in impelling a given body; and on the other hand, from the
effects or velocities with which given bodies are impelled by an
elastic fluid, we certainly know the force or strength of that fluid,
and these effects we have found perfectly to accord with the force
above mentioned. Mr. Robins’s discovery and opinions have also been
corroborated by others, among the best chemists and philosophers.
Lavoisier was of opinion that the force of fired gunpowder depends,
in a great measure, on the expansive force of uncombined caloric,
supposed to be let loose in a great abundance, during the combustion
or deflagration of the powder. And Bouillon Lagrange, in his course
of Chemistry says, when gunpowder takes fire there is a disengagement
of azotic gas, which expands in an astonishing manner when set
at liberty; and we are even still ignorant of the extent of the
dilatation occasioned by the heat arising from the combustion.
A decomposition of water also takes place, and hydrogen gas is
disengaged with elasticity; and by this decomposition of water there
is formed carbonic acid gas, and even sulphurated hydrogen gas, which
is the cause of the hepatic smell emitted by burnt powder.
It has been found by experiment, that granulated powder inflames
with much greater rapidity than that which is not granulated; the
latter only puffs away slowly, while the other takes fire almost
instantaneously; and of the granulated kinds, that in round grains
much sooner than that in oblong irregular grains; the cause of which
may arise from the former leaving to the flame larger and freer
interstices, which produce the inflammation with much more rapidity.
Gunpowder is supposed to explode at about 600° Fahr. but if heated to
a degree just below that of faint redness, the sulphur will mostly
burn off, leaving the nitre and charcoal unaltered.
Experiments have also proved, that the variations in the state of the
atmosphere do not any way alter the action of powder. By comparing
several trials made at noon in the hottest summer sun, with those
made in the morning and evening, no certain difference could be
perceived; and it was the same with those made in the night, and in
winter. And indeed, considering the principles of the explosion, and
that it always contains the same quantity of the elastic fluid, it is
difficult to conceive how its force can be affected by the density or
rarity of the atmosphere.
The action and nature of this formidable composition being now
somewhat fully described, we shall proceed to the principal object of
our Work, that of constructing the most common and curious articles
for Pyrotechnic exhibitions.