Fire-jets are produced by certain compositions, which are employed in cases, and are charged solid. They are formed and used according to taste or fancy.
The jets are made with a caliber of from one-third of an inch, to one inch and one-third, in interior diameter. They are seven or eight exterior diameters in length, and are charged in the usual manner with the composition, hereafter mentioned, driving each charge with twenty blows with a small mallet. The first charge must be the common fire composition.
Some of the compositions in the following table have already been mentioned, when treating of certain fire-works; but we deem it of importance to notice them in a connected manner, so that we may have the formulæ in one view.
Fire-jets, it must be remembered, are calculated as well for turning, as for fixed pieces.
The cases charged with this composition are only employed for furnishing the centre of some pieces, the movement of which depends on other cases; for these, having no force, would not move the piece.
| Blue Fire, for any caliber. | ||
| Meal powder, | 16 oz. | |
| Saltpetre, | 2 — | |
| Sulphur, | 8 — | |
| Radiant Fire, idem. | ||
| Meal powder, | 16 oz. | |
| Filings of pins, (d'epingles) | 3 — | |
| Green Fire, idem. | ||
| Meal powder, | 16 oz. | |
| Filings of copper, | 3 — | 2 dr. |
| Aurora Fire, idem. | ||
| Meal powder, | 16 oz. | |
| Gold powder, (Poudre d'or) | 3 — | |
| For Italian roses or fixed stars. | ||
| Meal powder, | 2 oz. | |
| Saltpetre, | 4 — | |
| Sulphur, | 1 — | |
| Another, for the same. | ||
| Meal-powder, | 12 oz. | |
| Saltpetre, | 16 — | |
| Sulphur, | 10 — | |
| Antimony, | 1 — | |
The jets of fire, which are various according to the composition employed, may appear under several forms, sometimes in one and sometimes in another; and hence they may put on an asteroid appearance, or that of a fountain, or water spout, or the form of rain. The effect, however, is very elegant; and, in conjunction with other species of fire-works, cannot fail to change the general appearance, by modifying the whole, or rendering it more various.
These compositions are generally used in the manner before mentioned, in cases of different sizes; but they may, under particular circumstances, be employed otherwise. In fact, the forms which may be given to the flame of gunpowder, or the substances which compose it, either by increasing or retarding its combustion, or changing the appearance of the flame, and giving it the form of jets, stars, rain, &c. are so numerous, that it furnishes alone an important branch of Pyrotechny. These effects will be detailed, when we treat of the formation of compound works.