Aquatic Fire-Works.
Though fire and water are of very opposite natures, yet there are many fire-works, which will burn and produce their effect even when immersed in their opposite element; of these rockets are the most pleasing. They may be made from four ounces to two pounds. The cases are made as those for sky-rockets, differing only as it regards the thickness of them, which should be somewhat greater, and in the manner of filling, which latter is the most particular, requiring a variety of compositions rammed in alternate layers, for the purpose of making them alternately dive and swim. The compositions are chiefly of three kinds, namely, that of sulphur two ounces, salt-petre four ounces, and mealed-powder one ounce and a-half, and about one fourth of an ounce of antimony. The second kind called a sinking charge, is composed of eight ounces of mealed-powder, and three-fourths of an ounce of charcoal. The third, called an ordinary charge, composed of mealed-powder, salt-petre, sulphur, and charcoal, varied as in the following proportions: sometimes a small portion of sea-coal or saw-dust is blended with them.
1. Mealed-powder six pounds, salt-petre three pounds, charcoal five pounds.
2. Mealed-powder four pounds, salt-petre four pounds, sulphur two pounds.
3. Mealed-powder four ounces, salt-petre one pound, sulphur eight ounces and a-half, charcoal two ounces.
4. Mealed-powder one pound, salt-petre three pounds, sulphur one pound, charcoal nine ounces.
5. Salt-petre one pound, sulphur four ounces and a-half, charcoal six ounces.
In filling, one ladle-full of slow-fire is first rammed in the case; then one or two of sinking charge; the common and the sinking charge are placed alternately to within about two diameters of the top. Over the last layer is placed one ladle-full of dry clay; and a perforation made through into the charge. The remainder of the case upwards, to within about half a diameter, is filled with corn-powder, and two or three folds of the paper turned over it; when the ramming paper at the end is secured with strong thread, and afterwards dipped in melted pitch or wax. When several rockets are thrown into the water at the same time, care should be taken to select those which have been filled and rammed in an uniform manner. To secure the cases from the action of the water, it is obvious that they should be prepared as such; this is done by varnishing them over with linseed oil, or common varnish.
Leaders, and pipes of communication, must be prepared after the same manner as rockets, as far as regards their cases; that is, they must be made somewhat stronger, and when fixed to be varnished over as before; taking care not to varnish before all your pasting is completed.