GUNPOWDER
, a composition of nitre, sulphur, and charcoal, mixed together, and usually granulated. This easily takes fire; and when fired, it rarefies or expands with great vehemence, by means of its elastic force.—It is to this powder that we owe all the effect and action of guns, and ordnance of all sorts. So that fortification, with the modern military art, &c, in a great measure depends upon it. The above definition however is not general, for instead of the nitre, it has lately been discovered that the marine acid answers much better.
The invention of Gunpowder is ascribed, by Polydore Virgil, to a chemist; who having accidentally put some of this composition in a mortar, and covered it with a stone, it happened to take sire, and blew up the stone. Thevet says that the person here spoken of was a monk of Fribourg, named Constantine Anelzen; but Belleforet and other authors, with more probability, hold it 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. But there are earlier accounts of its use, after the accident of Schwartz, as well as before it. For Peter Mexia, in his Various Readings, mentions that the Moors being besieged in 1343, by Alphonsus the 11th, king of Castile, discharged a kind of iron mortars upon them, which made a noise like thunder; and this is seconded by what is related by Don Pedro, bishop of Leon, in his chronicle of king Alphonsus, who reduced Toledo, viz, that in a sea-combat between the king of Tunis and the Moorish king of Seville, about that time, those of Tunis had certain iron tubs or barrels, with which they threw thunderbolts of fire.
Du-Cange adds, that there is mention made of gunpowder in the registers of the chambers of accounts in France as early as the year 1338.
But it appears that Roger Bacon knew of Gunpowder near 100 years before Schwartz was born. He tells us, in his Treatise De Secretis Operibus Artis. & Naturæ, & de Nullitate Magiæ, cap. 6, (which is supposed by some to have been published at Oxford in 1216, and which was undoubtedly written before his Opus Majus, in 1267), “that from saltpetre, and other ingredients, we are able to make a fire that shall burn at what distance we please.” And Dr. Plott, in his History of Oxfordshire, pa. 236, assures us that these “other ingredients were explained in a MS. copy of the same treatise, in the hands of Dr. G. Langbain, and seen by Dr. Wallis, to be sulphur and wood coal.” Farther, in the life of Friar Bacon in Biographia Britannica, vol. 1, we are told 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 said 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 the biographer apprehends the words carbonum pulvere were transferred to the 6th chapter of Langbain's MS. In this same chapter Bacon expressly says that sounds like thunder, and corruscations, may be formed in the air, much more horrible than those that happen naturally. And farther 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 300 men: Judges, chap. 7. There is also another passage to the same purpose, in the treatise De Scientia Experimentali. See Dr. Jebb's edition of the Opus Majus, p. 474.
Mr. Robins, in the preface to his Gunnery, apprehends 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 his time.
But Mr. Dutens carries the antiquity of Gunpow-|
der still much higher, and refers to the writings of the ancients themselves for the proof of it. “Virgil, says he, and his Commentator Servius (Æneid, lib. 6, v. 585), Hyginus (Fabul. 61 and 650), Eustathius (ad Odyss, l 234, pa. 1682, lib. 1), La Cerda (in Virgil. loc. cit.), Valerius Flaccus (lib. i. 662), and many other authors (as Raphael Volatarran. in Commentar. Cornelius Agrippa poster. Oper. de Verbo Dei, c. 100, p. 237.—Gruteri Fax Artium Liberal tom. 2, p. 1236), speak in such a manner of Salmoneus's attempts to imitate thunder, as suggest to us that this prince used for that purpose a composition of the nature of gunpowder. Eustathius in particular speaks of him on this occasion, as being so very expert in mechanics, that he formed machines, which imitated the noise of thunder; and the writers of fable, whose surprise in this respect may be compared to that of the Mexicans when they first beheld the fire-arms of the Spaniards, give out that Jupiter, incensed at the audacity of this prince, slew him with lightning, as he was employing himself in launching his thunder. But it is much more natural to suppose that this unfortunate prince, the inventor of Gunpowder, gave rise to these fables, by having accidentally fallen a victim to his own experiments. Dion (Hist. Rom. in Caligula, p. 662) and Joannes Antiochenus (in Chronico, &c. a Valesio edita, Paris 1634, p. 804), report the very same thing of Caligula, assuring us that this emperor imitated thunder and lightning by means of certain machines, which at the same time emitted stones. Themistius informs us that the Brachmans encountered one another with thunder and lightning, which they had the art of launching from on high at a considerable distance; (Themist. Oratio 27, p. 337). And in another place he relates, that Hercules and Bacchus, attempting to assail them in a fort where they were entrenched, were so roughly received by reiterated strokes of thunder and lightning, launched upon them from on high by the besieged, that they were obliged to retire, leaving behind them an everlasting monument of the rashness of their enterprise. Agathias the historian reports of Anthemius Traliensis, that having fallen out with his neighbour Zeno the rhetorician, he set sire to his house with thunder and lightning. It appears from all these passages, that the effects ascribed to these engines of war, especially those of Caligula, Anthemius, and the Indians, could be only brought about by Gunpowder. And what is still more, we find in Julius Africanus a receipt for an ingenious composition to be thrown upon an enemy, which very nearly resembles that powder. But what places this beyond all doubt, is a clear and positive passage of an author called Marcus Græcus, whose work in manuscript is in the royal library at Paris, intitled Liber Ignium. Dr. Mead had the same also in manuscript, and a copy of that is now in my hands. (See above). The author describes several ways of encountering an enemy, by launching fire upon him; and among others gives the following. Mix together one pound of live sulphur, two of charcoal of willow, and 6 of saltpetre; reducing them to a very fine powder in a marble mortar. He adds, that a certain quantity of this is to be put into a long, narrow, and well compacted cover, and so discharged into the air. Here we have the description of a rocket. The cover with which thunder is imitated, he represents as short, thick, but half-silled, and strongly bound with packthread; which is exactly the form of a cracker. He then treats of different methods of preparing the match, and how one squib may set fire to another in the air, by having it inclosed within it. In short, he speaks as clearly of the composition and effects of Gunpowder, as any person in our times could do. I own I have not yet been able precisely to determine when this author lived, but probably it was before the time of the Arabian physician Mesue, who speaks of him, and who flourished in the beginning of the 9th century. Nay, there is reason to believe that he is the same of whom Galen speaks; in which case he will be of antiquity sufficient to support what I advance.” It appears too, from many authors, and many circumstances, that this composition has been known to the Chinese and Indians for thousands of years. See what is said on this head under the article Gun.
To this history of Gunpowder it may be added, that it has lately been discovered that saltpetre or nitre is not essential to this composition, but that its place may be supplied by other substances; for new Gunpowder, of double the strength of the old, has lately been made in France, by the chemists in that country, without any nitre at all; and in the year 1790 I tried some of this new powder, that was made at Woolwich, with my eprouvette, when I found it about double the strength of the ordinary sort. This is effected by substituting, instead of the nitre, the like quantity of the marine acid.
But perhaps this new composition may not come into common and general use; both because of the great expence in procuring or making the acid, and of the trouble and danger of preventing it from taking sire by the heat of making it; for it is found to catch fire and explode from a very small degree of heat, and without the aid of a spark.
As to the Prcparation of Gunpowder; there are divers compositions of it, with respect to the proportions of the three ingredients, to be met with in pyrotechnical writings; but the process of making it up is much the same in all.
For some time after the invention of artillery, Gunpowder was of a much weaker composition than that now in use, or that deseribed by Marcus Græcus; which was chiefly owing to the weakness of their first pieces. See Gun and Cannon. Of 23 different compositions, used at different times, and mentioned by Tartaglia in his Ques. and Inv. lib. 3, ques. 5, the first, which was the oldest, contained equal parts of the three ingredients. But when guns of modern structure were introduced, Gunpowder of the same composition as the present came also into use. In the time of Tartaglia the cannon powder was made of 4 parts of nitre, one of sulphur, and one of charcoal; and the <*>usket powder of 48 parts of nitre, 7 parts of sulphur, and 8 parts of charcoal; or of 18 parts of nitre, 2 parts of sulphur, and 3 parts of charcoal. But the modern composition is 6 parts of nitre, to one of each of the other two ingredients. Though Mr. Napier says, he finds the strength commonly to be greatest when the proportions are, nitre 3lb, charcoal about 90z, and sulphur about 30z. See his paper on Gunpowder in the Transactions of the Royal Irish Academy, vol. 2. The can-| non powder was in meal, and the musket powder grained. And it is certain that the graining of powder, which is a very considerable advantage, is a modern improvement. See the presace to Robins's Math. Tracts, pa. 32.
To make Gunpowder duly, regard is to be had to the purity or goodness of the ingredients, as well as the proportions of them; for the strength of the powder depends much on that circumstance, and also on the due working or mixing of them together.
To purify the nitre, by taking away the fixt or common salt, and earthy part. Dissolve it in a quantity of hot water over the fire; then filtrate it through a flannel bag, into an open vessel, and set it aside to cool, and to crystallize. These crystals may in like manner be dissolved and crystallized again; and so on, till they become quite pure and white. Then put the crystals into a dry kettle over a moderate fire, which gradually increase till it begins to smoke, evaporate, lose its humidity, and grow very white: it must be kept continually stirring with a ladle, lest it should return to its former figure, by which its greasiness would be taken away: after that, so much water is to be poured into the kettle as will cover the nitre; and when it is dissolved, and reduced to the consistency of a thick liquor, it must be continually stirred with a ladle till all the moisture is again evaporated, and it be reduced to a dry and white meal.
The like regard is to be had to the sulphur; choosing that which is in large lumps, clear and perfectly yellow; not very hard, nor compact, but porous; nor yet too much shining; and if, when set on fire, it freely burns all away, it is a sign of its goodness: so likewise, if it be pressed between two iron plates that are hot enough to make it run, and in the running appear yellow, and that which remains of a reddish colour, it is then fit for the purpose. But in case it be foul, it may be purisied in this manner: melt the sulphur in a large iron ladle, or pot, over a very gentle coal fire, well kindled, but not flaming; then scum off all that rises on the top, and swims upon the sulphur; take it presently after from <*>he fire, and strain it through a double linen cloth, letting it pass leisurely; so will it be pure, the gross matter remaining behind in the cloth.
For the charcoal, the third ingredient, such should be chosen as is large, clear, and free from knots, well burnt, and cleaving. The charcoal of light woods is mostly preferred, as of willow, and that of the branches or twigs of a moderate thickness, as of an inch or two in diameter. Dogwood is now much esteemed for this purpose. And a method of charring the wood in a large iron cylinder has lately been recommended, and indeed proved, as yielding better charcoal than formerly.
The charcoal not only concurs with the sulphur in supplying the inslammable matter, which causes the detonation of the nitre, but also greatly adds to the explosive power of it by the quantity of elastic vapour expelled during its combustion.
These three ingredients, in their purest state, being procured, long experience has shewn that they are then to be mixed together in the proportion before mentioned, to have the best effect, viz, three-quarters of the composition to be nitre, and the other quarter made up of equal parts of the other two ingredients; or, which is the same thing, 6 parts nitre, 1 part sulphur, and 1 part charcoal.
But it is not the due proportion of the materials only, which is necessary to the making of good powders another circumstance, not less essential, is the mixing them well together: if this be not effectually done, some parts of the composition will have too much nitre in them, and others too little; and in either case there will be a defect of strength in the powder. Robins, pa. 119.
After the materials have been reduced to sine dust, they are mixed together, and moistened with water, or vinegar, or urine, or spirit of wine, &c, and then beaten together with wooden pestles for 24 hours, either by hand, or by mills, and afterwards pressed into a hard, firm, and solid cake. When dry, it is grained or corned; which is done by breaking the cake of powder into small pieces, and so running it through a sieve; by which means the grains may have any size given them, according to the nature of the sieve employed, either finer or coarser; and thus also the dust is separated from the grains, and again mixed with other manufacturing powder, or worked up into cakes again.
Powder is smoothed, or glazed, as it is called, for small arms, by the following operation: a hollow cylinder or cask is mounted on an axis, turned by a wheel; this cask is half filled with powder, and turned for 6 hours; and thus by the mutual friction of the grains of powder it is smoothed, or glazed. The fine mealy part, thus separated or worn off from the rest, is again granulated.
The Nature, Effects, &c, of Powder.—When the powder is prepared as above, if the least spark be struck upon it from a steel and flint, the whole will immediately inflame, and burst out with extreme violence.—The effect is not hard to account for: the charcoal part of the grain upon which the spark falls, catching fire like tinder, the sulphur and nitre are readily melted, and the former also breaks into flame; the contiguous grains at the same time undergoing the same fate.
Sir Isaac Newton reasons thus upon the point: 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 eolipile; 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 fixt body of the nitre, lets loose the spirit of the nitre, and excites a greater fermentation, by which the heat is farther augmented, and the fixt 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 takes fire, the explosion will be far more violent and quick than that of Gunpowder alone; which cannot proceed from any other cause, than the action of the vapour of the Gunpowder upon the salt of tartar, by which that salt is rarefied.
The explosion of Gunpowder therefore arises from the violent action, by which all the mixture <*>eing quickly| and vehemently heated, is rarefied and converted into fume and vapour; which vapour, by the violence of that action becoming so hot as to shine, appears in the form of a flame.
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 of it, and in the intervals or spaces between the grains: the powder being kindled, sets the springs of so many little parcels of air a-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.
But it appears from the experiments and observations of Mr. Robins, that if this air be in its natural state at the time when the powder is fired, the greatest addition its elasticity could acquire from the flame of the explosion, would not amount to five times its usual quantity, and therefore could not suffice for the 200th part of the effort which is exerted by fired powder.
To understand the force of Gunpowder, it must be considered that, whether it be fired in a vacuum or in air, it produces by its explosion a permanent elastic fluid. See Philos. Trans. number 295; also Hauksbee's Phys. Mechan. Exp. p, 81. It also appears from experiment, that the elasticity or pressure of the fluid produced by the firing of Gunpowder, is, cæteris paribus, directly as its density.
To determine the elasticity and quantity of this elastic fluid, produced from the explosion of a given quantity of Gunpowder, Mr. Robins premises, that the elasticity of this fluid increases by heat, and diminishes by cold, in the same manner as that of the air; and that the density of this fluid, and consequently its weight, is the same with the weight of an equal bulk of air, having the same elasticity and the same temperature. From these principles, and from the experiments by which they are established (for a detail of which we must refer to the book itself, so often cited in these articles), he concludes that the fluid produced by the firing of Gunpowder is nearly 3/10 of the weight of the generating powder itself; and that the volume or bulk of this air or fluid, when expanded to the rarity of common atmospheric air, is about 244 times the bulk of the said generating powder.—Count Saluce, in his Miscel. Phil. Mathem. Soc. Priv. Taurin. p. 125, makes the proportion as 222 to 1; which he says agrees with the computation of Mess. Hauksbee, Amontons, and Belidor.
Hence it appears, that any quantity of powder fired in any confined space, which it adequately fills, exerts at the instant of its explosion against the sides of the vessel containing it, and the bodies it impels before it, a force at least 244 times greater than the elasticity of common air, or, which is the same thing, than the pressure of the atmosphere; and this without considering the great addition arising from the violent degree of heat with which it is endued at that time; the quantity of which augmentation is the next head of Mr. Robins's enquiry. He determines that the elasticity of the air is augmented in a proportion somewhat greater than that of 4 to 1, when heated to the extremest heat of red hot iron; and supposing that the flame of sired Gunpowder is not of a less degree of heat, increasing the former number a little more than 4 times, makes nearly 1000; which shews that the elasticity of the flame, at the moment of explosion, is about 1000 times stronger than the elasticity of common air, or than the pressure of the atmosphere. But, from the height of the barometer, it is known that the pressure of the atmosphere upon every square inch, is on a medium 14 3/4 lb; and therefore 1000 times this, or 14750lb, is the force or pressure of the flame of Gunpowder, at the moment of explosion, upon a square inch, which is very nearly equivalent to 6 tons and a half.
This great force however diminishes as the fluid dilates itself, and in that proportion, viz, in proportion to the space it occupies, it being only half the strength when it occupies a double space, one third the strength when triple the space, and so on.
Mr. Robins farther supposes the degree of heat above mentioned to be a kind of medium heat; but that in the case of large quantities of powder the heat will be higher, and in very small quantities lower; and that therefore in the former case the force will be somewhat more, and in the latter somewhat less, than 1000 times the force of the atmosphere.
He farther found that the strength of powder is the same in all variations in the density of the atmosphere. But that the moisture of the air has a great effect upon it; for the same quantity which in a dry season would discharge a bullet with a velocity of 1700 feet in one second, will not in damp weather give it a velocity of more than 12 or 1300 feet in a second, or even less, if the powder be bad, and negligently kept. Robins's Tracts, vol. 1, p. 101, &c. Farther, as there is a certain quantity of water which, when mixed with powder, will prevent its firing at all, it cannot be doubted but every degree of moisture must abate the violence of the explosion; and hence the effects of damp powder are not difficult to account for.
It is to be observed, that the moisture imbibed by powder does not render it less active when dried again. Indeed, if powder be exposed to very great damps without any caution, or when common salt abounds in it, as often happens through negligence in refining the nitre, in such cases the moisture it imbibes may perhaps be sufficient to dissolve some part of the nitre; which is a permanent damage that no drying can retrieve. But when tolerable care is taken in preserving powder, and the nitre it is composed of has been well purged from common salt, it will retain its force for a long time; and it is said that powder has been known to have been preserved for 50 years without any apparent damage from its age.
The velocity of expansion of the flame of Gunpowder, when fired in a piece of artillery, without either bullet or other body before it, is prodigiously great, viz, 7000 feet per second, or upwards, as appears from the experiments of Mr. Robins. But Mr. Bernoulli and Mr. Euler suspect it is still much greater. And I suspect it may not be less, at the moment of explosion, than 4 times as much.
It is this prodigious celerity of expansion of the flame of fired Gunpowder, which is its peculiar excellence, and the circumstance in which it so eminently| surpasses all other inventions, either ancient or modern: for as to the momentum of these projectiles only, many of the warlike machines of the ancients produced this in a degree far surpassing that of our heaviest cannon shot or shells; but the great celerity given to these bodies cannot be in the least approached by any other means but the flame of powder.
To prove Gunpowder. There are several ways of doing this. 1, By sight: thus, if it be too black, it is a sign that it is moist, or else that it has too much charcoal in it; so also, if rubbed upon white paper, it blackens it more than good powder does: but if it be of a kind of azure colour, somewhat inclining to red, it is a sign of good powder. 2, By touching: for if in crushing it with the fingers ends, the grains break easily, and turn into dust, without feeling hard, it has too much coal in it; or if, in pressing it under the fingers upon a smooth hard board, some grains feel harder than the rest, it is a sign the sulphur is not well mixed with the nitre. Also by thrusting the hand into the parcel of powder, and grasping it, as if to take out a handful, you will feel if it is dry and equal grained, by its evading the grasp, and running mostly out of the hand. 3, By burning; and here the method most commonly followed for this purpose with us, says Mr. Robins, is to fire a small heap of it on a clean board, and to attend nicely to the flame and smoke it produces, and to the marks it leaves behind on the board: but besides this uncertain method, there are other contrivances made use of, such as powder-triers acting by a spring, commonly sold at the shops, and others again that move a great weight, throwing it upwards, which is a very bad sort of eprouvette. But these machines, says Mr. Robins, though more perfect than the common powder-triers, are yet liable to great irregularities; for as they are all moved by the instantaneous stroke of the flame, and not by its continued pressure, they do not determine the force of the fired powder with sufficient certainty and uniformity. Another method is to judge from the range given to a large solid ball, thrown from a very short mortar, charged with a small quantity of powder; which is also an uncertain way, both on account of the great disproportion between the weight of the ball and powder, and the unequal resistance of the air; not to mention that it is too tedious to prove large quantities of powder in this way; for, “if each barrel of powder was to be proved in this m<*>ner, the trouble of charging the mortar, and bringing back the ball each time, would be intolerable, and the delay so great, that no bu iness of this kind could ever be finished; and if a number of barrels are received on the merit of a few, it is great odds, but some bad ones would be amongst them, which may prove a great disappointment in time of service.” These exceptions do “noways hold, continues Mr. Robins, against the method by which I have tried the comparative strength of different kinds of powder, which has been by the actual velocity given to a bullet, by such a quantity of powder an is usually esteemed a proper charge for the piece: and as this velocity, however great, is easily discovered by the motion which the pendulum acquires from the stroke of the bullet, it might seem a good amendment to the method used by the French (viz, that of the small mortar above mentioned) to introduce this trial by the pendulum instead of it. But though I am satisfied, that this would be much more accurate, less laborious, and readier than the other, yet, as there is some little attention and caution required in this practice, which might render it of less dispatch than might be convenient, when a great number of barrels were to be separately tried, I should myself choose to practise another method not less certain, but prodigiously more expeditious; so that I could engage, that the weighing out of a small parcel of powder from each barrel should be the greatest part of the labour; and, doubtless, three or four hands could, by this means, examine 500 barrels in a morning: besides, the machines for this purpose, as they might be made of cast iron, would be so very cheap, that they might be multiplied at pleasure.” Robins, page 123. It is not certainly known what might be the particular construction of the eprouvette here hinted at, but it was probably a piece of ordnance suspended like a pendulum, as he had made several experiments with a barrel in that manner. Be this however as it may, several persons, from those ideas and experiments of Mr. Robins, have made eprouvettes on this principle, which seems to be the best of any; and on this idea also I have lately made a machine for this purpose, which has several peculiar contrivances, and advantages over all others, both in the nature of its motion, and the divisions on its arc, &c. It is a small cannon, the bore of which is about one inch in diameter, and is usually charged with 2 ounces of powder, and with powder only, as a ball is not necessary, and the strength of the powder is accurately shewn by the arc of the gun's recoil. The whole machine is so simple, easy, and expeditious, that, as Mr. Robins observed above, the weighing of the powder is the chief part of the trouble; and so accurate and uniform, that the successive repetitions or firings with the same quantity of the same sort of powder, hardly ever yield a difference in the recoil of the 100th part of itself.
To recover damaged Powder. The method of the powder merchants is this; they put part of the powder on a sail-cloth, to which they add an equal weight of what is really good; then with a shovel they mingle it well together, dry it in the sun, and barrel it up, keeping it in a dry and proper place.
Others again, if it be very bad, restore it by moistening it with vinegar, water, urine, or brandy; then they beat it fine, sift it, and to every pound of powder add an ounce, or an ounce and a half, or two ounces (according as it is decayed), of melted nitre; and afterwards these ingredients are to be moistened and well mixed, so that nothing may be discerned in the composition; which may be known by cutting the mass, and then they granulate it as useful.
In case the powder be quite spoiled, the only way is to extract the saltpetre with water, in the usual way, by boiling, filtrating, evaporating, and crystallizing; and then, with fresh sulphur and charcoal, to make it up afresh.
On the subject of Gunpowder, see also Euler on Robins's Gunnery, Antoni Examen de la Poudre, Baumé's Chemistry, and Thompson's Experiments in the Philos. Trans for 1781.
