Artificial fire-works

by Robert Jones

Of the Method of mixing Compositions.

The performance of the principal part of fireworks depends much on the compositions being well mixed; therefore great care ought to be taken in this part of the work, particularly in the compositions for sky rockets. When you have four or five pounds of ingredients to mix, which is a sufficient quantity at a time (for a larger proportion will not do so well), first put the different ingredients together, then work them about with your hands, till you think they are pretty well incorporated; after which put them into a lawn sieve with a receiver and top to it; and if, after it is sifted, any remains that will not pass through the sieve, grind it again till fine enough; and if it be twice sifted it will not be amiss; but the compositions for wheels and common works are not so material, nor need not be so fine. But in all fixed works, from which the fire is to play regular, the ingredients must be very fine, and great care taken in mixing them well together; and observe that, in all compositions wherein are steel or iron filings, the hands must not touch, nor will any works, which have iron or steel in their charge, keep long in damp weather, without being properly prepared, according to the directions given in the following article.

How to preserve Steel or Iron Filings.

It sometimes may happen, that fireworks may be required to be kept a long time, or sent abroad; neither of which could be done with brilliant fires, if made with filings unprepared; for this reason, that the saltpetre being of a damp nature, it causes the iron to rust, the consequence of which is, that when the works are fired, there will appear but very few brilliant sparks, but instead of them a number of red and drossy sparks, and besides, the charge will be so much weakened, that if this should happen to wheels, the fire will hardly be strong enough to force them round: but to prevent such accidents, prepare your filings after the following manner.

Melt in a glazed earthen pan some brimstone over a slow fire, and when melted throw in some filings; which keep stirring about till they are covered with brimstone, this you must do while it is on the fire; then take it off, and stirr it very quick till cold, when you must roll it on a board with a wooden roller, till you have broke it as fine as corn powder; after which sift from it as much of the brimstone as you can. There is another method of preparing filings, so as to keep two or three months in winter; this may be done by rubbing them between the strongest sort of brown paper, which before has been moistened with linseed oil.

N. B. If the brimstone should take fire, you may put it out, by covering the pan close at top: it is not of much signification what quantity of brimstone you use, so that there is enough to give each grain of iron a coat, but as much as will cover the bottom of a pan, of about one foot diameter, will do for five or six pound of filings: cast iron for gerbes may be preserved by the above method.

The Method of Driving or Ramming Sky Rockets, &c.

Rockets which are drove over a piercer must not have so much composition put in them at a time, as when drove solid, for the piercer, taking up great part of the bore of the case, would cause the rammer to rise too high: so that the pressure of it would not be so great on the composition, nor would it be drove every where equal: to prevent which, observe the following rule; that for those rockets, that are rammed over a piercer, let the ladle[5] hold as much composition as when drove, will raise the drift one half the interior diameter of the case, and for those drove solid to contain as much as will raise it half the exterior diameter of the case: ladles are generally made to go easy in the case, and the length of the scoop about one and a half of its own diameter.

The charge of rockets must always be drove one diameter above the piercer, and on it must be rammed one third of a diameter of clay, through the middle of which bore a small hole to the composition, in order that, when the charge is burnt to the top, it may communicate its fire, through the hole, to the stars in the head: great care must always be taken, to strike with the mallet, and with an equal force, the same number of strokes to each ladle-ful of charge; otherwise the rockets will not rise with an uniform motion, nor will the composition burn equal and regular; for which reason they cannot carry a proper tail, for it will break before the rocket has got half way up; instead of reaching from the ground to the top, where the rocket breaks and disperses the stars, rains, or whatever is contained in the head. When you are ramming, keep the drift constantly turning or moving; and when you use the hollow rammers, knock out of them the composition now and then, or the piercer will split them: to a rocket of four ounces, give to each ladle-ful of charge sixteen strokes: to a rocket of eight ounces twenty-one strokes: to a rocket of one pound, twenty eight: to a two pounder, thirty-six: to a four pounder forty-two: and to a six pounder fifty strokes; but rockets of a larger sort cannot be drove well by hand, but must be rammed with a machine made in the same manner as those for driving piles, which are so very common to be seen, that I shall here omit giving a description of them.

The method of ramming of wheel cases, or any other sort, in which the charge is drove solid, is much the same as sky rockets; for the same proportion may be observed in the ladle, and the same number of strokes given, according to their diameters, all cases being distinguished by their diameters; in this manner, a case whose bore is equal to a rocket of four ounces is called a four ounce case, and that which is equal to an eight ounce rocket an eight ounce case, and so on, according to the different rockets.