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.

Saltpetre,12 parts.

Meal-powder,12——

Sulphur,4——

Antimony,4——

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.

Grained powder,6 lbs.

Meal-powder,2—

Saltpetre,1—

Sulphur,½—

Charcoal,10oz.

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:

Chlorate, or hyperoxymuriate of potassa8 oz.

Flowers of sulphur3 —

Charcoal of light wood2 —

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.

Linseed Oil3 lbs.

Spirit of Turpentine1 —

White of egg¼ —

Quicklime8 —

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.

Saltpetre24 parts.

Sulphur7 ——

Red arsenic2 ——

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.

Sulphur8 parts.

Saltpetre4 ——

Gunpowder2 ——

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.