Part 5
You should keep all these ingredients ready powdered, dried, and sifted through your 40-mesh sifter; and then, when you require stars, you will having nothing to do but to weigh out the proportions given in the formula, and mix them on paper with a spatula. The more you handle the nitrate of strontia, or any composition containing it, the moister it will become, and the less effect it will produce. Therefore do not think of mixing the ingredients till you are ready to make your stars, and have a convenient, dry, warm place in which to stow them when made.
You can procure the things mentioned in the above receipt, and, in fact, those required for all the coloured compositions, of Mr. Darby, 98, Regent Street, Lambeth.
But, in case you may think it desirable to prepare and dry your nitrate of strontia yourself, I give you the following directions—
Procure a common earthenware pipkin, or, still better, a glazed iron frying-pan of a convenient size. Into this place your nitrate of strontia in rough crystals. One or two pounds will be sufficient to prepare at a time. Place the vessel on a clear fire, but do not make it too hot. There is not the slightest danger of explosion, as this salt cannot be induced to burn except in combination with other things. You must now boil, or rather stew, the crystals in their own water of crystallisation. The heat will soon cause them to run into a thick pulpy mass. When in this state, they must be _constantly stirred_, or upon the evaporation of the moisture they will resume a crystalline form. This you wish particularly to avoid, as your object is to get this mass into _powder_. Continue then to stir it with a stick or flat piece of wood until the moisture is driven off by the heat, and the salt remains in the condition of a white dry sand. A few trials will enable you to perform this operation in such a manner that after it the strontia will be ready at once for use. If, however, enough stirring did not take place, you will find some fused lumps among your dry preparations; these must be pounded in a mortar, and afterwards dried.
The operation described above is very simple, and does not take long to perform. No strontia can be used for coloured stars or fires _unprepared_. If, after keeping the dried nitrate of strontia for some time, you find that it is again becoming moist, it may be re-dried, either in the vessel used above, or in an open dish placed in a well-heated oven. This operation is proper also for the preparation of the nitrate of baryta.
For the solution of shellac you will find the following plan a convenient one:—Make a very strong solution of the resin in methylated spirit of wine, which shall be as thick as treacle. As you require your thinner solution for moistening coloured star compositions, dilute a portion of the thicker solution with the methylated spirit to the strength required.
The sulphur used in all coloured compositions should be as free as possible from acid; otherwise, when mixed with chlorate of potash, it may be dangerous. If you have any doubt about it, wash the sulphur in a solution of common potash in water, and dry it gradually. The acid will be entirely neutralised by this plan. Never think of pounding sulphur and chlorate of potash together; they form a detonating compound which will explode with friction or percussion.
The compositions that I here give for colours are _perfectly safe_ when made as I direct. I have made coloured stars from them, and placed these stars at the side of a fireplace till they have become so hot that I could not bear them in my hands, and I have subjected them to several tests, all of which they have stood well; and I think I may safely recommend them to you as not at all liable to spontaneous combustion or possessed of any dangerous quality. I must tell you, however, that _they may be heated till they explode_, but it is _quite unnecessary and very foolish_ to expose them to any high temperature at all. In drying them, a good plan is to put them in front of a fire in a flat tin box, which will prevent any chance of their being ignited, and will at the same time keep them in a thoroughly dry atmosphere till they become perfectly hard. The box may be placed about two feet from the fire, so that it becomes moderately warm.
In filling the pill-boxes with composition, put a piece of quick-match through them, as directed above, and hold them by the two projecting ends of match. Let a short groove be cut in the side of the stick with which you press in the composition, large enough to allow it to pass the quick-match without injuring it.
ROSE-COLOURED STARS.
18. I now give you a composition for producing
ROSE-COLOURED STARS.
No. 2. Chlorate of potash 20 parts. Carbonate of strontia 8 „ Calomel 10 „ Shellac 2 „ Sulphur 3 „ Charcoal (fine) 1 part
The advantage of this composition is that it is not at all liable to suffer from damp in winter. The carbonate of strontia is a salt not deliquescent like the nitrate, and is, moreover, always to be had in a state of fine powder. The colour procured by the above formula is not so deep as that which the first composition will produce; but it is especially beautiful when contrasted with an intense blue. If its combustion should be thought too rapid, less of the chlorate of potash may be employed. It is to be moistened with the solution of shellac.
GREEN STARS.
19. Our next colour will be the green. I have especially observed that stars of this colour always appear far more intense when burning at a distance than when close to the spectator. The colour produced by the nitrate of baryta is never very deep where any great rapidity of combustion is required. It is, however, an exceedingly pretty tint, and is seen to its greatest advantage when used in contrast with a rich red. I employ the following formula for
GREEN ROCKET STARS. No. 3. Chlorate of potash 20 parts. Nitrate of baryta 40 „ Calomel 10 „ Sulphur 8 „ Shellac 3 „ Charcoal (fine) 1 part. Sulphide of copper 1 „
The composition made according to this formula will produce a colour which leaves nothing to be desired, if the several ingredients be only _in fine powder, dry, and pure_. It is not affected by moisture nearly so much as any composition containing nitrate of strontia. The shellac employed should be as fine as possible. And here let me remark that the reduction of shellac to powder is a process of itself; no coarsely-powdered shellac will answer your purpose. Mr. Darby will supply you with it in _fine_ powder quite as cheaply as you can get it done elsewhere. Composition No. 3 is to be moistened with the solution of shellac. The sulphide of copper you may have some difficulty in procuring. You are sure, however, to meet with it at the shop of Messrs. Bolton and Co., 146, Holborn-Bars, London, but you must ask for the _fused_ sulphide of copper, for there is a _precipitated_ sulphide also, which is of no use to you. Do not use any of it that will not pass through your 40-mesh sifter. I add this ingredient rather as an improvement than as necessary to the composition. You may substitute for it, if you please, the preparation of copper which I am about to recommend in the composition for blue stars. If composition No. 3 should be thought too fierce, try the addition of a little more calomel.
PALE ROSE-COLOURED STARS.
20. The next formulas that I shall give are two which I have occasionally used and found effective. Their merit is that they possess a very intense illuminative power; their colour, however, is not so intense as that of those which I have already given. They have also the advantage of being very readily ignited, but care must be taken not to expose them to a high temperature in drying. The following are their formulas:—
PALE ROSE-COLOURED STARS. No. 4. Nitrate of strontia 8 parts. Chlorate of potash 4 „ Sulphur 3 „ Sulphuret of antimony 2 „
Take especial care that the nitrate of strontia used in this formula be very dry.
21. PALE-GREEN STARS.
PALE-GREEN STARS. No. 5. Nitrate of baryta 16 parts. Chlorate of potash 8 „ Sulphur 6 „ Antimony 3 „
The compositions made from both these formulas give a pale colour when seen close; but when falling from a rocket, and viewed at a distance, produce a very charming effect, particularly when contrasted one against the other. They must be moistened with the solution of shellac.
GOLDEN-YELLOW STARS.
22. The next colour that we will deal with is the yellow. The composition for this colour is a very satisfactory one, on account of its having no tendency to deterioration from damp. There are many formulas used for this colour directing the use of the nitrate of soda. This salt is, if anything, more difficult to keep dry than the nitrate of strontia. I therefore have abandoned it for another preparation, which I believe to be _as effective_ and thoroughly permanent. I recommend the following for
GOLDEN-YELLOW STARS. No. 6. Chlorate of potash 20 parts. Nitrate of baryta 30 „ Oxalate of soda 15 „ Sulphur 8 „ Shellac 4 „
If it be thought advisable to give the stars made from this formula a tailed appearance, add one part of fine charcoal. The composition is to be moistened with the shellac solution. The stars form a beautiful contrast with those of an intense blue.
BLUE STARS.
23. And now comes the last, and, in my opinion, the most beautiful colour of all. This is the blue. It has generally been considered a very dangerous colour, but the following formulas I have always found thoroughly safe:—
BLUE STARS. No. 7. Chlorate of potash 8 parts. Sulphide of copper 6 „ Chertier’s copper 5 „ Sulphur 4 „
Or,
No. 8. Chlorate of potash 12 „ Chertier’s copper 6 „ Sulphur 4 „ Calomel 1 part.
These formulas give a rather pale but very brilliant blue. The compositions have the advantage of being very readily ignited.
PURPLE STARS.
24. If a deeper blue is required, use the following, which I shall dignify by the name of
PURPLE STARS. No. 9. Chlorate of potash 16 parts. Chertier’s copper 12 „ Calomel 8 „ Stearine 2 „ Sulphur 2 „ Shellac 1 part.
This gives the most intense blue that I have seen used in pyrotechny, and, with crimson or yellow stars, forms a truly magnificent contrast.
Chertier’s copper is a preparation discovered by a Frenchman of that name, and particularly adapted to the requirements of the pyrotechnist. It is made as follows:—Take any quantity of common sulphate of copper (blue vitriol) and dissolve it in as little water as possible; then take an _equal_ quantity by weight of chlorate of potash and dissolve it also in as little water as will hold it in solution. Mix these two solutions, and boil them _gently_ over a clear fire until the moisture is nearly evaporated; then dry the green precipitate that remains _by a gentle heat_. _When dry_ treat it with strong liquor ammoniæ till it changes to a _deep blue_ colour; then let it dry very gradually in a warm place. If this operation be properly performed you will have a fine, very light blue powder, which is in reality a _chlorate of potash with copper and ammonia_. This is what I designate as Chertier’s copper. Messrs. Bolton and Co. will no doubt prepare it for you if you please.
The stearine employed in the above composition must be in fine powder. It is easily reduced to this state by being treated in the same way as camphor or spermaceti. If a few drops of spirits of wine are used with it, it can be powdered in a mortar.
Compositions Nos. 7, 8, and 9, must be moistened, NOT _with the solution of shellac, but with the gum-water_ which have recommended to be used in making up the _brilliant_ stars. Care, however, should be taken that for this purpose the gum-water has not become acid by long standing. A very little of the fluid will make the composition bind well, and will enable you to form from it stars of great tenacity and hardness.
I think now that want of variety is a thing that you can hardly complain of; but I must beg you to bear in mind the following particulars:—
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.
[Illustration:
Fig. 32. ]
[Illustration:
Fig. 33. ]
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.