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.