We find that col. Gibbs, (American Journal of Science, i. 87), in a letter to professor Silliman, mentions the use of lime in increasing the strength of gunpowder. He gives a certificate of the person, whom he employed in blowing rocks, in which he used quicklime along with powder, in the proportion of one part of the former to two of the latter. In the certificate, it is stated, that a charge of this mixture was found to be equally powerful, or to "answer equally well with a like quantity of gunpowder," having made upwards of fifty blasts in this manner, and, as he states, several hundred in the usual way. He remarks, however, that, when the powdered lime was mixed with the gunpowder the day before, the effect was diminished. The colonel attributes the effect to the desiccation of the powder by the lime; and, as gunpowder absorbs more or less water, the lime, in its caustic state, takes it from the powder. If the lime should remain too long, he is of opinion that it would probably attack the water of crystallization of the saltpetre, and, according to count Rumford's idea, destroy a great part of the powder. "The examination of this subject," says Gibbs, "led me to consider the increase of the power of gunpowder in various situations, and of its use in the field. It is well known, that, after a few discharges, a cannon becomes heated, and the range is much greater, as well as the recoil. The charge of powder is, therefore, reduced about one-quarter, to produce the original effect. As I have not heard or seen any explanation of this fact, I shall take this opportunity of mentioning, that it appears to arise from the same cause as the first explained, viz: the desiccation of the powder, &c."

M. Humboldt, (Bulletin de la Société Philomatique, floreal, an. 3) it appears, suggested an improvement in mining, not by increasing the force of gunpowder, but in the charging of it; to leave a space occupied only by air, a fact well known to those who are accustomed to this work, although not always adopted. He states the effect of powder on a shell; that, if it be filled, it breaks only into two or three pieces; but if only half filled, it is shattered into a great number, which he attributes to the presence of air in the shell.

Sec. XXXIII. Of Incendiary Bombs.

These are used in sieges, and on water. Ruggeri gives the preparation of these bombs as follows, observing to melt the substances in the order they are mentioned.

1.   Three parts of sulphur;
2.   One part of pitch;
3.   Two parts of nitrate of potassa;
4.   One part of mutton suet.

After melting these substances, and mixing them intimately, the mixture is removed from the fire, and two pounds of gunpowder are added, and thoroughly blended. It is again submitted to heat, and a sufficient quantity of quick match, to cover a good sized marron, is immersed. The marron is furnished with a fuse. The composition hardens on the match. The match is employed as before described. Water does not extinguish the fire, produced by the combustion of this composition. See Carcasses and Fire-Balls.

Sec. XXXIV. Of Murdering Marrons.

Marrons, which take this name, are those, whose effect is different from the incendiary bomb. The latter is calculated to set fire to houses, &c. while the former is designed to destroy the lives of persons.

To make a murdering marron, we prepare, in the usual manner, a cylindrical case, and fill it with gunpowder, and then wrap round it, a quantity of pack-thread. In winding on the thread, care must be taken to cross it in the manner mentioned in a former article. It is then finished by coating it with a mixture of glue and wax, or, in preference, pitch. This prevents the thread from unwrapping, and renders the case firm and less liable to break. A hole is then made in its side to the powder, in which we insert a piece of quick-match, to communicate fire to the contents of the case. A small fuse, similar to that of a bomb fuse, but shorter, and made of pasteboard, is also used; and, after it is fixed to the marron, musket balls, previously pierced with holes, are nailed round the marron, the nails passing through the balls into the case. After thus fixing as many balls as the surface of the case will admit, we cover them with a composition made of three parts of glue and one part of wax. When this coating is dry, a hemispherical case is adapted. This case is a small sack of paper, made round, and filled with gunpowder. It is placed at the bottom of the marron, and secured there with paper and glue. The match is conveyed to the orifice of the fuse of the marron; and, in short, a communication is so made from the one to the other, that, at a given time, the fire passes by means of the fuse to the marron, which then explodes, and throws the balls, with which it is furnished, in every direction.

Shells, made by uniting two hemispheres, containing powder, and furnished with balls and a fuse, are also a destructive weapon of the same character.

Sec. XXXV. Of Incendiary Rope.

We have mentioned, under the head of Tourteaux, or tarred links and fascines, the compositions made use of for these preparations. The composition for incendiary rope is as follows:

The rosin, sulphur, camphor, and saltpetre are melted, and mixed thoroughly together, and the kettle, which contains them, is removed from the fire; the gunpowder is then added, and intimately blended.

The mixture is again heated, and the rope is then immersed in it, and suffered to remain until it has imbibed sufficiently. It is then taken out, and allowed to cool.

After this operation, we melt, in a separate kettle, the following substances:

When they are melted, and mixed, the rope previously prepared as above, is thrown into the mixture, and then removed and hung up.

After this second process, we make, in an earthen vessel, a priming mixture, in which the rope is sometimes immersed, or such parts of it, as are to take fire promptly. This priming paste is composed of,

Incendiary rope is used more generally in the form of a ball, which is enclosed in a sack, and fired out of a common mortar. It was invented by an officer at Toulon. See Carcasses.

Sec. XXXVI. Of Balloons of Grenades, of Bombs, and of Flints or Stone.

Balloons of this kind are cases, or sacks, made sufficiently large, containing powder, and enclosing grenades, shells, and stones.

The balloon of grenades holds twelve charged grenades, containing different quantities of powder. They are finished like powder sacks, and corded with small cord, twine, or thread. The balloon of flints, river stones, or small pebbles, is made by enclosing these substances along with powder in a sack, as before stated. These balloons are employed for the defence of works, &c. See Powder Sacks.

The Ballon à Bombes, of the French, is the same. It is a bag, in which are placed beds of smaller bombs, that are charged and interlaid with gunpowder. The bag is put into another covering, that is pitched, with the neck closely tied up with pack thread, in which a fuse is fixed, as in ordinary bombs. The English say, that Colonel Shrapnel's invention of the spherical case shot, is of a superior kind. We purpose, therefore, to notice them in the following section.

Sec. XXXVII. Of Spherical Case-Shot.

2nd. Grape, or case shot, may be fired with effect equally close and collected, to any distance within the range of the piece; and the artillery need not advance within musket shot of the enemy, to make use of this kind of fire with its full effect, and are not so subject to have their guns charged either by cavalry or infantry.

3d. It requires less precision and exactness, to point a piece of ordnance charged with spherical case shot than with round shot; because case shot is a wide and dispersed fire, and the difficulty in elevation consequently less.

4th. Its comparative destruction with that of round shot will be, generally, as the number of the shot within the shells to one; that is to say, a three pounder, twenty-two to one in its favour; a six pounder, fifty to one, &c.; in which calculation is not enumerated any effect from the splinters of the shell.

5th. Small balls cannot be projected to very considerable distances, unless enclosed in heavy spherical cases, which, from their form and weight, are not much influenced by the resistance of the air, or diverted from their direction.

6th. The explosion of the shell makes no change in the direction of the shot within; they consequently complete the shell's track, or curve, which has sometimes been observed to be 400 yards.

7th. From the unevenness of the ground, such as hillocks, banks, fallow fields, &c. all shot which graze, most commonly lodge: whereas, by using this shell, the whole charge will be carried over these irregularities, and reach the object with its full contents of balls.

Sec. XXXVIII. Of the Fire-Rain, according to Casimir Siemienowicz.

The composition, which produces fire-rain, which we purpose to notice in this place, is taken from the "Artis Magnæ Artilleriæ" of Casimir Siemienowicz. He seems, however, to have taken it from a German author.

The fire rain is an incendiary fire-work, and calculated, like other incendiaries, for firing the houses of a besieged place or city, which are covered with shingles, laths, stubble, or reeds. Besides several other compositions, designated by artificers, that of fire-rain was so called from its supposed resemblance to a shower of rain.

To prepare this composition, the following method is used: We take 24 parts of sulphur, and melt in a copper, or iron pot, over live coals without flame, and then throw in 16 parts of saltpetre, and mix it with an iron spatula, to incorporate the whole. The pot is now removed from the fire, and when the composition is become rather cold, stir into it 8 parts of grained powder. The composition is then poured on a marble slab, or metallic plate, where it is allowed to cool. It is then broken into pieces of the size of a walnut, which, when used, is interspersed with quick match, covered with gunpowder, and put into shells or bombs.

These bombs are made in the same manner, as those, which are formed in fire-works for exhibition.

Wood, covered with this composition, will burn in the same manner as the shells. The globe of fire is also similar to those for exhibition. The mortar is elevated at an angle of 45°, in order that the globe may go to the greatest height, and the greatest range; for the fall of the inflamed matter, which is dispersed in all directions by the powder, is more or less vertical, and, in that state, lights upon houses, &c. This effect, that of setting fire to one or more houses, depends greatly on the accuracy of their discharge from the mortar.

The following compositions are also used for the same purpose, observing to follow the same manner of mixing the ingredients:

These compositions may be used in the manner already described. Two wooden hemispheres, filled with the preparation and joined together, is the usual mode of forming a fire bomb. The bomb or globe is then covered with strong canvass, and finished by dipping it, or smearing it with melted pitch. Over this, two or three covers of canvass are sometimes sewed. When the bomb is dry, we put it in a case, in the same manner as directed for the murdering, and incendiary bombs. The case is charged with fine meal-powder, &c.

The modern improvements, which are many, supersede the rain-fire. Fire stone, for instance, is a more powerful preparation. The incendiaries made with this composition, and the ordinary carcass, are more effectual for this purpose. That the Greek fire was an active composition, and produced very destructive effects on towns and shipping, there can be no doubt; notwithstanding the invention of gunpowder has completely changed the art of war, and superseded, as we have shown in our articles on gunpowder and Greek fire, the use of the incendiary composition of the Greeks.

Sec. XXXIX. Of the Effect of Mirrors in inflaming Bodies at a Distance.

As this subject may be of some interest to the reader, at least in relation to an important fact, that of the concentration of the calorific rays of the sun, which has had the effect of burning bodies at some distance, we deem the following facts not irrelevant.

The effects of burning glasses, both by refraction and reflection, are noticed by Empedocles and Euclid, who composed a treatise on the ancient optics and catoptrics. It has been thought, that the Romans had a method of lighting their sacred fire by some such means. Aristophanes, in one of his comedies, introduces a person as making use of a globe, filled with water, to cancel a bond that was against him, by thus melting the wax of the seal. Plutarch, in his life of Numa, says, that the instruments used to kindle fires, were metallic dishes, which were placed opposite to the sun, and the combustible matter in the centre, by which, it is probable, he meant the focus, conceiving that to be at the centre of the mirror's concavity.

Father Kircher was the first, who thought of substituting, for a concave mirror, several plane mirrors, so disposed, that the sun's rays reflected at their surface might converge towards the same point. He employed five only of these mirrors, which he so arranged, that the concurrence of the rays should take place at a distance of more than one hundred feet, and he found the heat there to be scarcely supportable. "Now," says Kircher, "if five mirrors produce so considerable an effect, what would a hundred or a thousand do, arranged in the same manner? They would excite so violent a heat, that it would set fire to every thing, and reduce all to ashes."

Orpheus compares his jaspis to rock crystal, and says that it kindles fire, and that he knew how to use rock crystal as a burning glass. Diodorus calls some kinds of jasper transparent, and sky-coloured. The jaspis, described in the Revelation of St. John (chapter xxi, verse 11, 18, 19,) may have been the same stone.

It is not our intention, however, to notice the history of mirrors, from the time of Moses, (Exodus, chap. xxxviii, verse 8,) or of Job, (Job, chap. xxxvii, verse 18) through different periods of time, to the present day; as the reader may find an interesting account on this head in Beckman, (History of Inventions, vol. iii, p. 154); but to state in particular the celebrated experiment of Archimedes, which has indeed astonished men of science, who have lived since that period. There can be no doubt of the fact, if we reflect for a moment, that some modern experiments have justified the conclusion which has been drawn; and, therefore, that the solar rays may be concentrated to such a degree, as to inflame bodies at some distance off: and as the heat produced is much greater than that of our hottest furnaces, incredible as it may appear, there can be no question as to the effect, which may be produced by a system of mirrors.

By means of burning mirrors, Archimedes burnt the Roman ships, which were beseiging Syracuse, and reduced them to ashes.

Descartes, among others, discredited the story as fallacious; but Kircher made many experiments, with a view of establishing its credibility. He tried the effect of a number of plane mirrors, and with five mirrors of the same size, placed in a frame, he contrived to throw the rays reflected from them to the same spot, at the distance of more than one hundred feet; and, by this means, he produced such a degree of heat, as led him to conclude, that, by increasing their number, he could have set fire to inflammable substances at a greater distance. He likewise made a voyage to Syracuse, in company with his pupil, Schottus, in order to examine the place of the supposed transaction; and they were both of opinion, that the galleys of Marcellus could not have been more than thirty paces from Archimedes.[42]

Proclus is also said to have destroyed the navy of Vitalian, beseiging Byzantium, near Constantinople, by means of burning glasses.

Among the moderns, the most remarkable burning mirrors have been those of Magine; of Septala of Milan, which was nearly three and a half feet in diameter, and which burnt at the distance of fifteen or sixteen paces; of Vilette, and Tschirinhausen; the new complex one of M. Buffon; that of Trudaine, and that of Parker. Tschirinhausen's burning glass was between three and four feet in diameter, and its focus was rendered more powerful by a second one.

It may not be improper to notice the construction, as well as the effect of some of these mirrors. La Brocquire, a traveller of the 15th century, says, that, at Damascus, they made mirrors of steel that magnify objects, and one of them, when exposed to the sun, reflected the heat so strongly, as to set fire to a plank fifteen or sixteen feet distant.

M. Buffon constructed a machine consisting of a number of mirrors, by which he seems to have revived the secret of Archimedes, and to have vindicated the credit of history in this point. The experiment was first tried with twenty-four mirrors, which readily set on fire a combustible matter prepared of pitch and tow, laid on a deal board at a distance of sixty-six French feet. He then pursued the attempt, and put together a kind of polyhedron, consisting of one hundred and sixty-eight pieces of plane looking glass, each six inches square; and by means of this, some boards of beech wood were set on fire at a distance of one hundred and fifty feet, and a silver plate was melted at the distance of sixty feet. This machine, in the next stage of its improvement, contained 360 plane mirrors, each 8 inches long, and 6 broad, mounted on a frame 8 feet high, and 7 feet broad. With 12 of these mirrors, light combustible matters were kindled at a distance of 20 feet; with 45 of them, at the same distance, a large tin vessel was melted; and with 117, a thin piece of silver. When the whole machine was employed, all the metals were melted at the distance of twenty-five, and even of forty feet. Wood was kindled in a clear sky, at the distance of 210 feet. Mr. Buffon afterwards constructed a machine, which contained four hundred mirrors, each six inches square, with which he could melt lead and tin at the distance of 140 feet.

Mr. Parker, an eminent glass manufacturer, in Fleet street, London, constructed the most powerful burning mirror ever made. He erected an out building at the bottom of his garden for the purpose of carrying on his operations. He succeeded in forming a most powerful burning lens. Its diameter was three feet. Platinum, iron, steel, flint, &c. were melted in a few seconds, on being exposed to its immense focus. A diamond weighing thirty grains was reduced to six grains, in the space of thirty minutes. It opened and foliated like the leaves of a flower, and emitted whitish fumes, (carbonic acid gas;) when close again, it bore a polish, and retained its form. Garnets, clay, &c. soon melted.

Seven hundred guineas were subscribed to indemnify the inventor, it having cost him seven hundred pounds. It was purchased, however, and presented by lord Macartney to the Chinese government, and remains now at Pekin.

M. Payard, (Archives des Découvertes, &c.) has invented a burning mirror, consisting of several plane mirrors so arranged as to concentrate the solar heat into a focus with great precision. The arrangement, it may be proper to state, is different from that heretofore used, and the effect is said to be very powerful.

A polygonal mirror, from a suggestion of the celebrated Buffon, was erected in the Botanic Garden at Paris, in 1747, and had also a very powerful effect. This mirror was composed of one hundred and sixty-eight plates of tinned or silvered glass, capable of moving in every direction and of being fixed at different degrees of inclination, so that there could be given to the whole, a form more or less concave, and the focus be thrown to different distances. This mirror set fire to wood at two hundred feet, and fused metals at forty-five feet.

As caloric, like light, follows the same laws with respect to its motion, and as the angle of incidence is equal to the angle of reflection, the radiation of heat, conducted after the manner of Pictet's experiment, has not only occasioned the combustion of gunpowder, but of other inflammable substances. But, for this purpose, the mirrors must be large and extremely bright. That heat radiates in all directions, and is reflected, and that the calorific rays may thereby be concentrated, are facts which are now universally admitted. The application of this principle, by using concave mirrors sufficiently large, has, we are informed, produced the explosion of gunpowder. They were placed about twelve feet apart. In the focus of one a live coal was put, which was constantly blown with a double bellows, and in the focus of the other some gunpowder. In all our experiments with the ordinary reflectors, we could never produce any thing like the heat necessary to inflame gunpowder. That the principle is substantiated by experiment is evident; for the rays of a heated body, or a substance which produces heat, as a lamp or candle, placed in the focus of a concave mirror, are reflected in parallel lines, and if another concave mirror be placed opposite to it at some distance, the calorific rays will be thus intercepted and reflected back in a focus. This focus, therefore, like the focus of a burning glass, is the concentration of all the parallel rays of heat.

Sec. XL. Of Incendiary and Poisoned Arrows.

While noticing this subject, we may also observe, that Louis XI first abolished the use of bows in France, introducing, in their place, the halberd, pike, and broadsword. The long bow was much in use by the English archers, and many laws were passed encouraging its use. In the time of Henry VIII, the parliament complained of the disuse of long bows.

The bow is now laid aside altogether as a war weapon. The arrows, made use of, were armed with barbed iron, and, among the aborigines of this and other countries, with a stone, formed in a particular manner, many of which are picked up in this country. We have found them at West Point. The natives were in the habit of poisoning their arrows, by using a particular composition, not known; the effect of which, however, when the arrow penetrated into the flesh, is always destructive.

Roggewein, (Voyage for the Discovery of Southern Lands) speaking of Batavia, observes, that, at this place, there are some of the Macassars, so famous for their little poisoned arrows, which they blow through a trunk. This poison is the juice of a tree, that grows in Macassar, and in the Bougie islands. They dip the points of their arrows in this juice, and then let them dry. The wound they give is mortal.

The natives of Ceylon are very dexterous with the bow and arrow; so also are the Hottentots, according to Kolben, in his Voyage to the Cape of Good Hope. A Hottentot arrow consists of a small tapering stick or cane, of about a foot and a half in length, pointed with a small thin piece of iron bearded, and joined to the stick or cane by a barrel. Their bows are made of olive, or iron wood, and the strings, of the sinews and entrails of beasts. When they attack a lion, tiger, or leopard, which they do with wonderful resolution and dexterity, they employ slings (hassagayes) and arrows, which for that purpose are usually poisoned.

Ellis (Voyage for the Discovery of a North-West Passage) speaks of the bows and arrows of the Eskimaux Indians, and the facility with which they use them, but not of poisoned arrows. Moore, (Travels into the interior of Africa) observes, that a native took him to his house, and showed him a great number of arrows, daubed over with a black mixture, said to be so venomous, that, if the arrow did but draw blood, it would be mortal, unless the person who made the mixture had a mind to cure it. For the man observed to him, that there were no poisonous herbs, whose effects might not be prevented by the application of other herbs.

Poisoned arrows, according to various historians, were used in the remotest periods of antiquity. The mode of treating wounds in the twelfth century, by using membrane like the present gold-beaters' skin, may be mentioned in relation to this circumstance. The Emperor, John Commenus, accidentally wounded himself in the hand with a poisoned arrow, while hunting, and applied a piece of skin to the wound. The emperor, however, died in consequence of the wound, after it had become inflamed under the pellicle; which, in large wounds, and when the skin is suffered to remain too long, is commonly the case, though the poison alone we are informed, would have been a sufficient cause of death. Other instances are also mentioned of death being occasioned by the poisoned arrow.

On the subject of poisoned arrows, the following outline is given on the authority of the author of the Dictionnaire de l'Industrie, vol. 3, p. 50.

The juice of the Mancenilier, or the Lianes des Marais, called in Guyanne Curare, is employed by some savages. The Arabs use the juice of a milky shrub, which they name chark, and called by the Persians gulbut samour. Indian arrows are said to be poisoned with the venom of serpents. The islanders of Java rub their darts with the blood and venom of the lizard Gecko, which they kill by whipping it to death. The needles of the Macassars, they poison with the juice of a tree, which is said to belong to the ahouai of America. At Ceylon they extract the venomous matter from the Nerium, or laurel rose. The ancient Gauls are said by M. Paw to have poisoned their arms with the juice of the Caprisiguier. In some cantons of the Pyrenees and Alps, they express the juice of the roots of the Aconitum, (thora), which they put on weapons.

M. Charles Coquebert, in a memoir read to the Philomatic Society, in 1798, observes, that the ancient European inhabitants employed three plants to poison their arrows; namely, Veratrum album, Helleborus viridis, and Aconitum Lysocitonum.

There have been obtained from the Society Islands some poisoned arrows, and a pot of the composition, in which they are dipped. It has the appearance of a black fluid extract, and seems to be an infusion or decoction of some plants, probably mixed with other substances.

With respect to the poisons obtained from the animal kingdom, they are principally liquid juices. Fontana, in particular, has paid attention to this subject. The poison of the viper, which is contained in two small vesicles of the mouth, when the animal bites, is forced, through the fangs, into the wound. If the vesicles be extracted, or the liquor prevented from flowing into the wound, the bite is harmless. Sharp instruments, as arrows, when they penetrate the skin, being covered with the poison, will have the same effect. Fontana made a set of experiments on the dry poison of the viper, and a similar set on gum arabic, and obtained the same results! Small birds and quadrupeds die immediately, when they are bitten by a viper; but to a man, the bite is not always fatal. The experiments and observations of Francini, (Abridg. Phil. Trans. ii, 8,) Mead, (On Poisons, p. 35,) Tyson, (Phil. Trans. vol. xii,) Fontana, Redi, Russel, the late Dr. Ramsay, of Charleston, (Phil. Mag. xvii, 125,) and Dr. B. S. Barton, (Amer. Phil. Trans. vol. ii, p. 100,) furnish an abundance of facts on the venom of the viper, and some on the antidotes to the bite. Dr. F. G. Gren, late professor at Halle, in Saxony, (Principles of Modern Chemistry, ii, p. 47), observes, in speaking of the experiments of Fontana, as the poison of the viper exhibits all the characteristic properties of gum, whether the gum be merely the vehicle of a peculiar venomous substance, which, upon investigation, escapes the notice of the senses? or whether this action upon living bodies, so different from its usual nature, be imparted to the gum, merely by a change in the proportions of its radicals, so slight as to be unobservable in its chemical analysis?

Mr. Misson (Travels through Germany and Italy) observes, that, at the arsenal at Venice, he saw some pocket cross bows, and steel arrows, with which the late lord of Padua used to kill such as passed by, without their knowing from whence they received their wounds.

Arrows were sometimes employed by the Grecians, for conveying their Greek fire. It seems, according to Gibbon, (History of the Decline and Fall of the Roman Empire, vol. vii, 284), that, among the different means of discharging it, that with the bow and arrow was one. For this purpose, flax or tow was dipped in the composition, and wrapped round the arrow, which was discharged the moment it was inflamed.

The Indians, and Africans in particular, have been very ingenious in poisoning several kinds of warlike instruments. The blades of swords, the barbs of arrows, balls, &c. they have prepared in such a way, as to be extremely poisonous.[43] See Poisoned Ball.

With respect to incendiary arrows, it will be sufficient to remark, that the barb, for this purpose, was furnished with a composition, which, when inflamed, was projected by the bow to the spot designed to be set on fire. They were not much employed, and at the present day, are entirely out of use. Tow, for instance, previously prepared with pitch, meal-powder, and turpentine, or a composition equally combustible, when wrapped round the head of an arrow, and thrown at the moment of its inflammation, would, in many cases, set fire to buildings. But, as the present system of employing incendiary fire-works, presents advantages decidedly in its favour, it is hardly probable, that the bow and arrow will ever be employed by civilized nations for that purpose. The ancient catapulta was particularly calculated for throwing incendiary compositions.

The catapulta was an engine, contrived for throwing arrows, darts, and stones, upon the enemy. Their power was so great, that they would project a stone of a hundred weight with an almost incredible force. Josephus, in noticing this machine, says, that the stones thrown out of it, beat down the battlements, knocked off the angles of the towers, and had a force sufficient to level a deep file of soldiers.

Sec. XLI. Of Pyrotechnical Sponge.

There are various species of agaric. The mushroom is a genus belonging to the order Fungi, and the boletus igniarius, spunk, or touch-wood, called also female agaric, is employed, not only as a match, but as a styptic. The fungous excrescences, which grow upon old oaks, ash trees, firs, &c. are all used for the same purpose. The Germans take the soft inner substance in preference to the hard, and after beating with a hammer to render it still softer, they boil it in ley, then dry it, and boil it again, in a solution of nitrate of potassa, and finally dry it in an oven for use.

The amadou of the French, is the same as our spunk, or pyrotechnical sponge. It is always made, like the latter, from various kinds of agaric, which constitute the spongy excrescence of trees. The French prepare it for use in the manner before stated. They prepare amadou, also, by soaking blue paper in a solution of nitre. They sometimes employ it in the state of tinder, and, for this purpose, burn it to a coal.

In the East Indies, there is a white spongy plant, which, when reduced to a kind of charcoal, furnishes a very good tinder.

Spunk, or pyrotechnical sponge, is generally made in Germany.

In the preparation of ordinary tinder, the best mode of carbonizing the old linen, instead of burning and then smothering the flame, is to char the rags in close iron vessels. It may be made more quick by soaking it in a solution of nitre, and then drying it.

Dry turf, or peat, is susceptible of inflammation by the spark, and, if previously soaked in a solution of nitre, the effect, we are told, is much the same as with spunk. Professor Beckman (History of Inventions, i, p. 333), remarks, that a spark falling accidentally on a turf moor, during a dry summer, often sets it on fire; and the conflagration it occasions, often lasts so long, that it cannot escape notice. Of the earth taking fire in this manner, there are many instances to be found in the ancients. One of the most remarkable, is that mentioned by Tacitus, (Annal., lib. xiii, cap. 57), who relates, that not long after the building of the city of Cologne, the neighbouring land took fire, and burned in such a manner, that the corn, villages, and every production of the fields, were destroyed by the flames, which advanced even to the walls of the city. This was certainly a morass set on fire.

Gmelin (Travels in Russia, 1768-69, vol. i, p. 22) speaks of a morass in Siberia, where a village was erected, which, on account of its situation, the inhabitants deserted. This morass was set on fire, and when he was there, had been burning for more than six months; and being very inflammable, produced much devastation.

Turf, which consists of a congeries of vegetable roots or fibres, partly in a dry and decomposed state, or partly carbonized, when separated from earthy matter, and treated in the same manner as the medullary excrescence of wood, may be advantageously employed in like manner; but it is to be remarked, that for this purpose, the small and more friable, and consequently the more decomposed part, should be preferred. That turf, or peat, has been used for fuel, from time immemorial, there can be no doubt; since it is furnished in some countries very abundantly, and its inflammability has been long known.

Sec. XLII. Of Extinguishing Flame with Fired Gunpowder.

The different methods for extinguishing fire in chimnies, by using salt, sulphur, &c. to smother the flame, as it is called, depend on one principle, that of producing either a gas or vapour, which supplies the place of atmospheric air, and as it is a non-supporter of combustion, extinguishes the flame. Carbonic acid gas would have the same effect as the sulphurous acid gas, produced by the combustion of sulphur, or the vapour of salt.

So long, however, as the air is permitted to have a draught, the fire will continue to burn; and hence, without making any remarks on the bursting of chimnies, by closing all the avenues, by which the air enters, as the fire must exert a lateral pressure, this plan is generally adopted.

It has been suggested, and in fact the suggestion is by no means new, that the smoke of fired gunpowder would extinguish flame. Some recommend firing a pistol up a chimney for this purpose, and others again, throwing gunpowder into the fire.

In the Dictionnaire de l'Industrie, iii, p. 31, I find some remarks on this subject. Besides the use of gunpowder, the vapour of water is recommended; but having some objections, among which, that of accelerating the current of air in particular, it is laid aside. Intercepting the passage of air seems to be preferred.

It appears, that the person, who first suggested the use of gunpowder for this purpose, was a Zachariah Greyl, of Augsburgh, in 1720.

The effect was attributed to the vapour of the gunpowder destroying the elasticity of the air; and the same effect is said to take place when the vapour of sulphur, or of volatile acids, is employed. It is hardly necessary to add, that this conclusion, of the diminution of the elasticity of the air, on which depends its fitness for combustion, (according to the theory then advanced), is altogether hypothetical; and the cause of the extinction of the flame, must be sought for in the substances themselves, producing an atmosphere, which is decidedly a non-supporter of combustion.

The Journal de Paris for 1785, and the Affiches de Province of the same year, recommend the use of brimstone. In the same work, page 454, it is said, that marine salt is employed with success for the extinguishing of fires; and that, when a certain quantity is thrown upon the fire, it evaporates in an instant, and displaces, by its fumes, the atmospheric air. In 1723, M. Hoffer invented his machine; and in 1781, M. Cadet de Vaux made some experiments before Leroy, Lavoisier, and Macquer, on the means of rendering bodies incombustible by saline substances, and different modes of extinguishing flame.

In 1722, the Germans announced, that, by means of a certain quantity of gunpowder, flame at all times might be extinguished. The secret, for such it was then considered, has been revived; for the same plan has lately been recommended by a modern writer. M. de Reaumur communicated to the French academy, an account of this contrivance, by which it appears, that the machine was a large box, or cask, that contained a large quantity of water; in the centre of which, was placed a case of sheet tin, containing some pounds of cannon powder. To this was attached a fuse. When it was inflamed, the gunpowder would burst the vessel, and disperse the water in every direction. See the Journal des Savants, 1725, p. 671.

In the Dictionnaire de l'Industrie, a prompt and certain method is recommended for cleaning the tunnel of chimnies. This is rather a novel plan. Of its efficacy we know nothing. It consists in taking a powder, composed of three parts of saltpetre, two parts of salt of tartar, and one part of flowers of sulphur, (or fulminating powder), and exploding it on a shovel up the chimney. The explosion indeed may detach the loose pieces of soot; but it cannot remove the harder crust, and besides, it would endanger the chimney taking fire.

We know that various contrivances have been used for the same purpose; and of the chimney cleansing machines, calculated to diminish the number of infant victims of a filthy and disgusting operation, that of Mr. Smart appears to possess every advantage, which (or a plan similar to it) is now in use in our cities. A description of this machine, and another by Hornblower, are given in Gregory's Mechanics, vol. ii, p. 138. The invention of Mr. Hornblower consists of a vessel, into which air is condensed, that communicates with a tube, charged with small gravel, which being blown up the chimney, brings down the soot.

Sec. XLIII. Of the Inflammable Dart.

This dart is made in the following manner. We take a common rocket case, of one inch exterior diameter, and charge it solid with the ordinary rocket composition. Some use one spoonful of earth, and three spoonfuls of the composition for fire lances, piercing the case, and attaching a quick match. This, however, appears altogether unnecessary, as the rocket composition is sufficient for the purpose. The match, in either case, is fixed in the end to set it off. To the end of the case is attached a dart, made of iron, and very sharp. This dart is secured in the head, in such a manner as to be kept firm. A stick is then lashed to the case in the usual way. It may be sent in the direction required. It appears, however, that, although it is calculated to be thrown on an enemy, it has not been much used; nor can it be considered an active weapon, compared with others, employed for similar purposes. One use for which it is recommended, is for the defence of buildings.

Sec. XLIV. Of the Firebrand.

The boute-feu of the French, which we have translated into firebrand, as the most appropriate term in the present instance, is used as an incendiary, and is nothing more than a long stick, furnished at one of its ends with two iron prongs, with sometimes the figure of a dragon's head, on which is rolled thick rope, previously prepared in the same manner as tourteaux. One end of this rope passes between the iron prongs. The boute-feu is calculated to set fire to buildings, &c. after the retreat of an enemy. It is only a convenient and expeditious mode of communicating fire. One end of the stick is pointed, and usually covered with iron, so as to stick in the ground.

Sec. XLV. Of the Fire Flask.

The fire flask, or fire bottle, is a bottle, either square or round, and charged with grain-powder, mixed with fire-stone, which is introduced and compressed with a stick. The bottle is then covered with a cloth, sewed on it, which is coated with pitch. The mouth is secured with parchment. When used, a match is inserted, and inflamed. It is then thrown by the hand.

Sec. XLVI. Of the Trompe-Route.

The trompe-route of the French is a light made use of at sea, to deceive the enemy. It is nothing more than a common fire lance, one inch in diameter, and twelve inches long, fixed in the centre of a round plank, which, when lighted, is let down upon the water. As it floats from the ship, the lights of the latter being darkened, the enemy, in pursuit, will follow the light, and by this means the ship escapes.

Sec. XLVII. Of Fire-Pots for Ramparts.

Rampart fire-pots are used, when an enemy approaches a work. They are furnished with grain-powder, and charged grenades without fuses, and sometimes also with fire stone. The pots are ordinary potters' ware, and, when they contain the ingredients, are covered with parchment. A match passes through the opening of the pot, and when used, is inflamed with a port-fire. The following composition is also used for rampart pots.

Composition for Rampart Fire-Pots.

These ingredients are mixed in a mortar with the oil of petroleum, or, if this cannot be had, good spermaceti oil, and made into a thick paste, about the consistence of dough, and then rolled into balls. The pots generally hold two rows of these balls, distributing through them grained powder. They are then finished by using fire stone composition, beaten into pieces, and mixed with an equal quantity of grained powder, and covered with meal-powder to facilitate the inflammation.

The pots are covered over with parchment, as in the former case. It is doubtful, whether fire pots, prepared in this way, have any advantages over those, made in the manner first described.

As to the shape of fire-pots, some are cylindrical, and others of the common figure. Sometimes they are furnished with an iron hoop, with a hook of iron, by which they are suspended. They are used, when equipped in that way, more for sea service, as a defence against small boats. They are hung over the side of the vessel, so as to come in contact with the boats. When designed in particular for that use, they are charged with the following composition:

Composition for Fire-Pots, for sea service.

With this composition, grenades are used, which are put into the pot with powder, fire-stone, &c. and a match is fixed as before mentioned.

We are told, that fire-pots, prepared in this manner, are a defensive, as well as a dangerous weapon, and that a vessel in the Indian seas was actually saved by them, when attacked by pirates. It appears, that she endeavoured to escape from her pursuers, and finding it in vain, the crew thought of making, and employing fire-pots, for their defence; as the number of the pirates was greater than their own crew. The effect was, that, not expecting that kind of reception, they were obliged to abandon their enterprize.

There is an incendiary fire-pot, which differs from that used in fire-works for exhibition, by being made of copper and very stout. It is charged with pieces of fire-stone, previously rolled in a paste of meal-powder and brandy. A charge of powder is put in the pot, and quick-match is fixed, which must be sufficiently long to hang over the pot, and then the fire-stone is thrown in. When the match is inflamed, the powder takes fire, and disperses the fire-stone. The better plan is to have a communication to the powder below, as in the pots of ordnance, or mortars for throwing fire-balloons. We see no particular advantage to be derived from the use of this pot; as a carcass or fire-ball, thrown out of a mortar, will do more execution, and at a greater distance than any of these contrivances. The carcass rocket, however, may be an exception, if we believe the account we have of it. As an incendiary, the fire-stone, put in a shell with powder, is more effectual than the fire-pot, we have just described.

Sec. XLVIII. Of Inflammable Balls.

Count Rumford (Bibliothèque Physico-Economique, 1812) has invented a composition, which is very inflammable, and, as it is used in balls, is for that reason so called. Equal parts of clay, pitcoal, and charcoal of wood, are mixed together, (having previously reduced them to powder), and made into a consistence with water fit to roll into balls. These balls are then dried for use.

They may be rendered more inflammable, by soaking them in a strong solution of saltpetre.

Count Rumford, when he recommended the use of clay with coal, was aware, that, in the combustion of coal, a considerable part of the heat was lost; whereas, although clay is incombustible, a greater part of this heat is retained by the clay, and given out gradually.

The inflammable ball may be considered more in the character of an economical fuel than in any other.

The only inconvenience attending these balls is, that, when prepared without nitre, which must add to the expense, they do not readily inflame; and, therefore, a fire must first be kindled, before they are used.

While noticing the use of clay in this manner, we may remark, that the economical brick, as it is called, is made nearly in the same way.

Two parts of clay, separated from stones, are mixed with one part of pitcoal. After the fire is kindled, the coal burns in the same manner, and the clay bakes.

Another composition is given in the Bibliothèque Physico-Economique, for March, 1812. It is composed of potters' clay, cow dung, street dirt, saw-dust of wood, turf, horse dung, straw, and tan. Besides these, pitch, tar, oils, and other combustible substances, are occasionally used, either with the above, or mixed with pitcoal in powder.

Observations on this preparation may be seen in the work quoted, or in the Archives des Découvertes, v, p. 137.

Sec. XLIX. Of Pauly's Inflammable Powder.

We mentioned, in a note to the article on guns, that M. Pauly had invented a musket, or fowling piece, which was discharged by percussion, instead of flint and steel, by using a priming powder made of chlorate of potassa.

It may be proper, however, to state, that the Rev. Dr. Forsyth made use of a similar powder, and for the same purpose, many years ago, of which we have already spoken. M. Thenard also has given a formula for a preparation of a similar powder.

A description of M. Pauly's improvement may be seen in the Archives des Découvertes, for 1812, p. 158, and in that of 1814, p. 174, where the composition of the powder is noticed; and also in the Bulletin de la Société d'Encouragement, for 1814.

This powder is composed as follows:

They are mixed together with Cologne water, or in its place with brandy, to which a small quantity of the solution of gum arabic is added.

The ingredients must be made as fine as possible, and intimately blended together.

This powder may be inflamed by a hammer, or by the condensation of air in a piston, a mode recommended by Pauly.

We have seen a fowling-piece, constructed according to M. Pauly's plan, and also the priming powder used.

Sec. L. Of Extemporaneous Fire.

There are several preparations, which have the effect of producing fire either by friction, or chemical action. Some of these preparations, we have noticed. The causes of spontaneous combustion may be referred to chemical decomposition, and the change of quiescent into distributable heat. We remarked, that a mixture of chlorate of potassa and sugar is inflamed, when brought in contact with sulphuric acid; that, in the slaking of quicklime, the heat is sufficient to inflame oils; that pyrites by decomposition very frequently sets fire to combustible bodies; that oil of turpentine is inflamed by nitric acid; that pyrophorus, when exposed to the air, takes fire, and also phosphorus by slight friction; and that, in all cases of combustion, either friction, an increase of temperature, or the action of some body, which is brought in contact, are necessary to produce the effect.

Water, when added to some substances and preparations, will produce fire. Thus potassium readily decomposes it, and the potassuretted hydrogen gas, which is produced in flames. The same may be said of phosphuret of lime and water; for the phosphuretted hydrogen gas inflames, when it comes to the air.

On some occasions, these substances may be employed as incendiaries.

Hanzelet remarks, that the following composition will produce inflammation with water.

Extemporaneous Fire.

It is doubtful, however, whether this composition will have that effect; although the heat produced by the slaking of quicklime is very considerable, and, as we remarked, spontaneous combustion, in several instances, has been referred to its agency. Lime, in the act of slaking, absorbs, and chemically unites with, water, which becomes solidified, converting it into a hydrate, whilst its latent caloric is set at liberty. This is a process, which puts quiescent heat in motion, to become distributable heat. See Introduction.

If the quantity of free caloric, thus generated, be sufficient, the turpentine and oil will necessarily inflame.

We may add, therefore, that a rapid transition of caloric, from a latent to a free state, as in combustion, is all that is required to produce effects of this kind; and, in short, all cases of spontaneous combustion may be accounted for on this principle; by considering the cause, which acts in those instances so powerfully, and in some instances instantaneously, and which changes caloric from a quiescent to a distributable state.

Dr. Irvine refers all cases of combustion to a change in the capacity of bodies for caloric; which depends on the nature of the products: if they have a greater capacity, no flame ensues, and the caloric remains more or less quiescent; if they possess a less capacity, flame is the consequence. There are exceptions to this doctrine.

In the emission of caloric, Dr. Black supposes, that it is given out, in consequence of the resulting attraction of the new compound for caloric being less than that of its ingredients, when separate. M. Curadou (Journal de Physique, 1809) observes, that, in preparing the artificial stone, one-half of which is composed of water, by mixing one part of sulphuric acid with two parts of clay, and a sufficient quantity of water, a higher temperature is produced than that of boiling water. In this instance, we find that, in the formation of sulphate of alumina, which envelopes the silica, the water is solidified, as in many other cases, and, while it forms a solid substance, the caloric of fluidity is liberated. The heat, he remarks, is sometimes so great as to set fire to inflammable substances.

Sec. LI. Of the Indian White Fire.

This preparation (feu blanc Indien of the French) is described in the Archives des Découvertes, &c. vol. ii, p. 300. It appears, that it was kept secret in France, and was used by the French astronomers for signals.

In 1807, M. de Zach published some account of it, in his Astronomical and Geographical correspondence.

The case, in which the composition is put, is ten inches in diameter and four in height; but may be of any size, according to the quantity of the composition to be burnt, and the degree of light required. It was seen 40 miles at sea. General Ray lighted, on the English coast, a case of this fire, which was seen very distinctly on the French coast.

Composition of White Fire.

This powder lights without explosion, and illuminates with great brilliancy. Care must be taken not to breathe the Arsenical vapours, which are produced by the combustion.

A case of six inches in diameter, and six inches high, burns three minutes. The light is said to injure the eyes.

The price of this powder is equal to that of ordinary gunpowder.

The match, which accompanies this preparation when it is sold, is made in the following manner: Pulverize four parts of saltpetre, two parts of gunpowder, two parts of charcoal, and one part of sulphur, and pass them through a sieve. Provide then a number of paper cases, made in the usual manner, or a roller, about the diameter of a quill, and two feet in length, and charge with the composition.

This match, when used, is attached to a stick. It will resist the action both of wind and rain.

An artificer of Marseilles proposes the following composition for matches.

Sec. LII. Of the Pyrophore of Defence.

An apparatus for defence, called the Pyrophore, was announced in a French publication in 1815. It may be applied, according to the author, in 24 hours for the defence of towns, roads, passages, and defiles.

The pyrophore itself is a square box furnished with a lid, and sufficiently large to contain fifty pounds of gunpowder. When it is filled, and to be used, it is fixed with cords, or chains, in such a manner as to be conveyed to a given point. The lid is furnished with cross pieces, which open it when necessary.

At the sides of the box are rings, made very strong and fixed in bolts, which go through the sides, and clenched. To each of these rings, a cord or chain is attached, furnished at each end with a crotchet.

This cord or chain runs upon two fixed pulleys, placed for instance, at the two extremities of a battery, and is managed by artillerists. The pyrophore is under cover. When it is conveyed to a certain place, where a bar or grate is fixed, it is stopped, by the contrivance before mentioned, the lid is raised, and the powder falls into a kind of funnel or gutter, at the end of which the explosion is made, to take effect.

It appears that the inventor had in view the conveyance of a given quantity of powder to a particular place, and by carrying a light to it by means of a cord, similarly fixed, to inflame it, when it had arrived at its destination.

It is impossible to make a machine of this kind effective; for the difficulty in arranging, and finally managing it, the enemy taking means to guard against it, are certainly obstacles, and strong objections to its use. Other means of defence, which we have pointed out, are preferable; although we admit, that, in some situations, a contrivance of this sort might be advantageously used, where, for instance, we wish to deposite a quantity of powder, to be in readiness for the approach of an enemy, without exposing men to an attack. What is more destructive than the thundering barrel, which is furnished with grenades, &c. &c. if set off among the assailants? See, for a minute account of this contrivance, the "Pyrophore, ou Moyen de defense générale, par un garde national: 20 pages grand in 8vo. avec un planche. Paris Dondey Dupré, 1815," and also the Archives des Découvertes, tome 8. p. 281.