Part 6
The stars of which I have at present spoken are only _for rocket purposes_; they are not to be used for Roman candles. Another plan is adopted with reference to these, and their preparation will be described in its proper place.
When these rocket stars are to be used some of the powder recommended before must be strewed among them; you can make that mixture weaker if you please, using one proportion of fine charcoal to _five_ or even _four_ of meal-powder.
The projecting ends of quick-match render these stars much more certain of ignition than the ordinary cubic stars.
It is advisable not to prepare your coloured stars until you are ready to use them, because, unless protected from damp in the most careful manner, they will lose some of their beauty, and you will thereby not be making the most of them. They may appear to you expensive things to prepare, but you must bear in mind that _two or three rockets containing them_ are quite sufficient for any one exhibition such as I suppose you will be likely to give.
Remember that the red, green, and blue or purple stars may be used _mixed_ with a very beautiful effect. The purple and golden, or purple and crimson, or rose, will also form excellent contrasts.
GOLDEN RAINS.
25. One species of rocket decoration, the manufacture of which I proposed to describe, remains yet to be considered. It is called _Golden Rain_, and with the details of its preparation we will conclude our subject of rocket-making.
Golden rains are made in the following manner:—Procure a piece of brass rod (I always prefer brass for formers, because it is not liable to rust, as is iron or steel), the diameter of which is 3–16ths of an inch, or rather less. The length of the former may be from 6 to 8 inches. You will now require some thin brown or cartridge paper, of which to make your cases. Cut this paper into short strips, about 2 inches wide, and long enough, when wrapped round the former, to make a case whose external diameter should be a quarter of an inch, or rather more. The former should have a cup-shaped, hollow cut in one of its ends, into which the paper may be turned, to form a closed end to your little cases. Paste your strips of cartridge paper all over, and also rub some paste on the former. Now, having turned back one end of your strips—(figs. 32 and 33)—roll it round the former, beginning in the manner here sketched, so that, instead of rolling a single edge of paper round the former, you are rolling a double one. The advantages of this plan for making cases will be more easy for you to see than for me to describe. I may state, however, that you insure, by adopting it, a very close and even fit of the case to the former; you secure the inner edge of the paper from coming unfastened, and you are much more certain that your strips will roll up straightly. This plan may be adopted, if you please, for all cases. I think it is, on the whole, the safest and best. The paste which you rubbed on the former will enable you to draw it out from the case without tearing or injury. But before removing the former entirely, draw it out only so far as to leave its cupped end a quarter of an inch inside one of the ends of your case—so far, in fact, that a quarter of an inch of your case remains unoccupied by the former. Now pinch in the paper that projects beyond the former, and drive it down with a tap upon your pasting slab, so that the twisted end is pressed into the cup of the former. By this means you will have a neat and secure end to your cases, which may be dipped afterwards into warm size or glue. If a little red lead be mixed with this size, it will solidify much more rapidly. This dipping the ends of the cases into size should not be done until they are dry from the paste.
Now we come to the filling of these little cases; and for this purpose you will require a simple apparatus, known among pyrotechnists as “the funnel and wire.” The funnel is usually made of tin, and has at its mouth a short tube, about a quarter of an inch long, the exterior diameter of which is equal to the exterior diameter of your brass former, so that it will exactly fit into the mouth of your golden rain cases. The wire should be of steel, about 1–10th of an inch in diameter, and at least 6 inches long. For convenience in working, it should have a small wooden handle. The handles sold in the tool-shops for engravers’ tools will answer very well. This is the whole of the apparatus required for making golden rains.
The composition employed for filling the cases is the following:—
GOLDEN RAINS. Meal-powder 6 parts. Nitre 1 part. Fine charcoal 2 parts.
Or,
Meal-powder 8 „ Fine charcoal 3 „
Let these ingredients be very intimately mixed. When the composition is ready for use, place the tubular mouth of the funnel in the mouth of one of your little cases; and then put the wire, through the neck of the funnel, down to the bottom of the case. Next, half fill the funnel with one of the above compositions. Now, steadying the case with one hand, raise the wire a little by its handle, and drive it down again. Continue to repeat this operation, giving the wire a succession of short, rapid strokes. You may give about fifteen strokes in five seconds. Each time the wire is raised, a small quantity of the composition falls round it into the case, and the descent of the wire has the effect of driving the composition firmly and compactly into its place. When the case is charged, the funnel must be removed, and the space that was occupied by its nozzle filled with gunpowder paste—gunpowder, that is, or meal-powder moistened with gum-water. This will prevent the composition from being shaken out of the cases, and at the same time forms the best method of priming them. Take care that this paste is pressed well into the mouth of the cases, and fills them.
PORTFIRES.
26. The “funnel and wire” operation is one to which the pyrotechnist has recourse for many purposes, one of which I may as well mention here, as it may fairly be said to come under the head of rocket manufacture—I mean the preparation of _portfires_.
The portfires, used for firing rockets and fireworks, are generally made in the following manner:—The former for this purpose should be of brass, and not less than a quarter of an inch in diameter, and the wire for filling them not less than one-eighth of an inch. Portfire cases are usually made very thin, three rounds of such paper as that on which the _Times_ is printed being quite sufficient. The cases are prepared in precisely the same manner as that described for golden rains, and are also primed in the same way. The following is the composition which I use for
PORTFIRES. Nitre 6 parts Sulphur 2 „ Meal-powder 1 part.
Portfires may be made of almost any size, according to the purpose for which they are intended. You will find three-eighths of an inch quite large enough for the inner diameter of any that you are likely to require. If they are to be used for firing exhibitions, you will find that 8 to 12 inches will be a convenient length. The funnel and wire apparatus is so cheaply made that you will be able to provide yourself with two or three sets of these tools, of different sizes, so as to answer any purpose.
We are thus brought to the conclusion of the subject of rockets and their accessories. I trust that I have made my method of operation sufficiently intelligible and plain. The main difficulty that meets any one who attempts to describe a delicate and particular system of working lies in the fact that when one is thoroughly conversant with his subject, particularly in all its minutiæ, he is very liable to overlook, or to treat as unimportant in his directions, some point because it appears trifling to him, and is never likely to be forgotten in _his_ practice, the involuntary omission of which, however, may be a frequent cause of failure in the hands of others. I have tried throughout to evade any possibility of misunderstanding; and if I have been too diffuse, it has been solely from the desire to avoid that which has certainly been the fault of almost all the treatises on pyrotechny that I have seen, viz., indistinctness arising from insufficiency of detail.
Our next subject shall be that of
ROMAN CANDLES.
27. Fireworks of this species are exceedingly beautiful and effective, especially when made with coloured stars, and fired in numbers. Their manufacture is somewhat difficult, but the difficulty is one well worth overcoming. I made a considerable series of experiments before I produced a Roman candle that answered my expectations. At last, however, I hit upon a plan which has never since failed in my hands, and I think that, if I can succeed in making my meaning understood, and you will undertake to follow my directions closely, you will find my plan a good one.
There are several conditions upon which success depends, and which it will be as well to enumerate. A poor Roman candle is not worth making. If you wish to produce one that will satisfy you, remember—
1st.—That you must have a composition to burn in the intervals between the stars, which will produce as good an effect when the Roman candle is almost spent as when first lighted—in fact, which will throw a jet of fire uniformly good throughout.
2nd.—That your stars must be hard enough to resist the pressure of the drift with which you consolidate the composition.
3rd.—That the stars must be of tolerably rapid combustion, otherwise they will not be ignited before they are blown into the air.
4th.—That the charges of powder for blowing the stars must be regulated to a great nicety. If too small, they will not throw them high enough; if too large, they may burst the case, or spoil the intended effect of the stars, or so disturb the composition below them that three or four of the stars will be fired in rapid succession, or almost instantaneously.
Now, the first thing to be considered is the size of which Roman candles are to be made. I make them of _one_ size only, for I have found that it is much more convenient to have but one size of stars to prepare, and one size of cases to roll, and one scale of powder-charge to remember, than to run the risk of confusion by having to think of various sizes. Besides, all the effect that these pieces are capable of can be produced by my one size. This size is _that called the 2-oz. Roman candle_. The former for the cases must be five-eighths of an inch in diameter, and should be 18 inches long.
These fireworks require rather a large amount of paper and imperial board for the manufacture of their cases. A good stout case may be made as follows:—Cut your sheets of 70-lb. brown paper into halves, and your sheets of imperial board into six equal pieces. One of these pieces, with one half-sheet of 70-lb. paper, will make one case. Paste your pieces of imperial board _all over_, as well as the sheets of paper. Rub some paste on your former, and proceed to roll a piece of the pasted board tightly and smoothly round the former till all but about two inches of it is rolled. Then take the pasted half-sheet of brown paper, and roll this upon the imperial board in the manner described for making golden rain cases. The method there given is of especial value when the cases that you are making are of considerable length, because it enables you to roll the paper and board very straightly, which cannot be done so easily by any other means that I know of. The cases thus made will be pasted throughout and can be easily removed from off the former. They will be about 14 inches long, which is a very good size. You can, of course, make them shorter for experiments, but you will find the above size not too large for exhibition purposes. I do not think it will do to make the cases very much thinner than I have directed, but a few experiments will decide what length or thickness of case succeeds best in your hands. I have given you my size, which I have no wish to alter.
Now the next thing to be done is to prepare the stars. These are made in a tubular mould, the exact size of which I have sketched in the page of illustrations, Fig. 37. But before giving you directions for making these stars, I may as well furnish you with a few formulas for their composition.
WHITE ROMAN-CANDLE STARS.
28. The brilliant stars may be made of the same composition as that given you for rocket stars of that kind. If, however, you require a _more white_ star, use the following:—
WHITE ROMAN-CANDLE STARS. Composition No. 1. Nitre 48 parts. Sulphur 10 „ Regulus of antimony 8 „ Realgar 6 „ Red lead 4 „ Shellac 1 part.
This formula gives a much purer white than the formula for ordinary brilliant stars, which are always bluish in tint. Composition No. 1 must be moistened with the solution of shellac recommended for rocket stars.
YELLOW ROMAN-CANDLE STARS.
29. Yellow Roman-candle stars may be made from the same formula as that given for yellow rocket stars.
GREEK ROMAN-CANDLE STARS.
30. Greek Roman-candle stars may be made from the formulas given for rocket stars; but there is also another formula, which produces a rather deeper tint, but is hardly rapid enough in combustion for rocket stars. It is the following:—
GREEN ROMAN-CANDLE STARS. Composition No. 2. Nitrate of baryta 40 parts. Chlorate of potash 20 „ Calomel 12 „ Sulphur 12 „ Shellac (fine) 4 „ Charcoal (fine) 1 part.
This composition must be moistened with the solution of shellac. It will produce a most lovely colour, if the _baryta be pure_.
CRIMSON, ROSE, BLUE, AND PURPLE ROMAN-CANDLE STARS.
31. The formulas for crimson, rose, blue, and purple Roman-candle stars are the same as given for rocket stars, and must be moistened with the liquid directed in my last paper as proper for each one.
You have now formulas for making brilliant, white, golden, green, crimson, rose, blue, and purple stars.
ROMAN-CANDLE STARS (To Make).
32. In order to make the stars, moisten the compositions _very slightly_. The mould in which these stars are shaped is a brass tube of a size proportioned to the size of the Roman-candle case, and is generally about one-sixteenth of an inch smaller in its inner diameter than the case. The drift with which the composition is pressed into the tube is made of boxwood or metal, and fits easily into the tubular mould. At one of its ends there is a wire point. Place the end having the point in the mould as far as it will go. You will find a space left at the end of the mould unoccupied by the drift. Press this empty end of the tube into the slightly-moistened composition until it is filled by it, so that the drift, being driven down upon the composition, will compress it into a firm cylindrical mass, into the centre of which the wire point projects. Figures 35, 37, and 39, represent the mould, drift, and finished star. When the star is thus formed in the mould the drift must be reversed, and its long plain end inserted, and the star pushed out. The object of making the star hollow is that it may dry and harden perfectly in its centre. If heat is employed to dry the stars, they have a tendency to harden outside rapidly, and thereby an impervious coating is formed, through which the inner moisture cannot evaporate. This difficulty is obviated by leaving a hole in the centre of the star, and this hole is made of use for another important purpose—namely, _the priming_ of the star.
My plan for insuring the ignition of the stars is, as far as I know, peculiar to myself, and I have the satisfaction of knowing that it has never failed me. Some pyrotechnists recommend the smearing of the star with a very combustible paste; this plan, however, must to some extent injure the colour of the star. I simply place a little piece of quick-match into the hole in the star, and allow it to project about a quarter of an inch above. By this means even slowly-combustible stars are ignited, and almost every chance of failure is avoided.
This priming, however, should not be done until the stars are to be put into the cases—at all events, till they are perfectly dry. Their drying may be effected naturally out-of-doors in the summer, when a very few hours’ exposure in the sun will render them thoroughly hard and fit for use. In the winter time, however, artificial heat should be used. I always find that the more rapidly, _up to a certain point_, these stars are hardened, the better they keep. Nothing, however, will be gained by hurrying them through this process, except a danger of their exploding. Place them carefully, and not touching one another, in a tin box having a lid, and let this box remain at such a distance before a fire that it can become thoroughly warm, _not hot_, till the stars are thought hard enough to be put away. They should be kept, when dry, in closely-stoppered bottles in a dry place. Each star will weigh, at least, thirty grains.
COMPOSITION FOR ROMAN CANDLES.
33. I must now suppose your stars and cases to be ready for use; and, therefore, the next thing to be considered will be the composition which is to form the intervals between the stars in the cases. For this purpose I give you three formulas.
COMPOSITION FOR ROMAN CANDLES. No. 1. Nitre 18 parts. Sulphur 6 „ Charcoal (fine) 7 „ Meal-powder 4 „
This composition is one which answers very well. I think, however, that the following is better, being rather more rapid in its combustion, and thus capable of producing a more decided effect when burning at the lower end of the case:—
No. 2. Nitre 16 parts. Meal-powder 8 „ Charcoal (fine) 6 „ Sulphur 6 „
This is the composition which I generally employ. Both of these formulas give rather a dusty mixture, and can be used with much greater cleanliness and comfort if slightly moistened. Only so much spirits of wine or gin must be used as will render them less dusty, and not wet. The following composition is very useful, but produces rather a jet of flame with sparks than a rich sparkling fountain:—
No. 3. Nitre 16 parts. Meal-powder 11 „ Sulphur 6 „ Antimony 4 „
This composition is of a more heavy and less dusty nature, but can also be slightly moistened, if you find it more convenient to use it when thus treated. Take care that in each case the ingredients are well mixed.
ROMAN-CANDLE CASES (To Fill).
34. Having selected one of the above compositions, you will now be ready to fill your cases. For this part of your work you will require a small turned block of wood, like that drawn in the page of illustrations (fig. 40). This block with its projecting piece is called a “settle.” One end of your Roman-candle case is pressed over the upper part of this settle, which is made of a size to fit into it tightly. By this means the case will be supported while it is being filled. The first thing to be done is to close up one end of the case. This is done by ramming in a small quantity of dry potter’s clay, such as you used for rockets; this being driven down over the top of the settle will form a very hard, firm end.
CHARGES FOR ROMAN CANDLES.
35. We now have to enter upon the most difficult part of the manufacture of Roman candles. This is the regulation of the charges of powder which are to blow the stars into the air. These are so small, and necessarily so, that unless their quantity be very accurately measured you are very likely to spoil the performance of the whole. The following table will give you _an approximate_ idea of the quantity that each charge should contain; but so much depends upon the _quality_ of the gunpowder which you employ, that it is impossible to give you anything more than an approximation:—
For the 1st star 3 grains. „ 2nd „ 4 „ „ 3rd „ 4 „ „ 4th „ 5 „ „ 5th „ 5 „ „ 6th „ 6 „ „ 7th „ 6 „ „ 8th „ 7 „ „ 9th „ 8 „ „ 10th „ 30 „
Gunpowder exerts more or less force in its combustion in proportion as it meets with more or less resistance. It is in accordance with this principle that those charges of gunpowder which are at or near the lower end of the Roman-candle case, are obliged to be much smaller than those placed nearer its mouth. If it were not so, and all the charges were alike, when the combustion reached a certain point the case would be burst. You must modify the quantities given in the above table until you produce the greatest and best effect with the greatest economy of power. I think that the five first charges will not require to be altered much. I have given charges for _ten_ stars. You need not, of course, put so many into the case; but you should not put in less than _eight_. All must depend in this matter upon the quantity of composition which you like to use in the intervals between the stars. _Only be sure to keep the two last charges of gunpowder always the same, and do not place the two last stars too near the mouth of the case._ The reason why these rules must be observed is that the force of the charges of gunpowder which lie near the mouth of the case is so soon spent, that if the stars are too near the mouth of the Roman candle they will do little more than fall out of the case, instead of being blown to their proper height. The first star means, not that one which is fired first from the Roman candle, _but that which is first put into it_.
Your best plan for measuring the charges of powder is to have some small scoops or ladles made of very thin sheet-brass, of the same shape as that used in filling rockets, and capable of holding exactly the right charge of powder for each star. This is the only plan that I am aware of for insuring with any accuracy the various quantities.
Now, having your stars primed, as directed above, with quick-match, your clay rammed firmly into the lower end of the case, and your composition ready moistened for use, you must cut some _thin_ touch-paper into squares of an inch in size. Next you must be provided with a round stick with a flat end, which will pass easily into the case from one end to the other, not shorter than _eighteen inches_. Your materials and apparatus are now complete.