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.