Part 5

I may as well, however, introduce you to a simple piece of apparatus which will enable you to perform this operation much more comfortably and cleanly. I have a small wooden tray made of mahogany, six inches square, and three-quarters of an inch deep, _inside measurements_. Into this I place a flat piece of wood, which fits very easily into the tray, and is half-an-inch thick. This acts as a _movable false bottom_. It will be readily seen that when this false bottom is in the tray, placed upon the other bottom, _the tray will be filled up so as to leave a depth of a quarter of an inch only unoccupied_. This space I fill with the moistened star composition, having first rubbed the surface of the false bottom with soap to prevent any adhesion taking place between the composition and the wood. Having now pressed into the tray as much composition as will fill it to the height of its sides, I score it with the spatula as directed above. A large hole is made in the _natural_ bottom of the tray, so that I can, by putting my fingers through it, raise the false bottom covered with stars out of the tray. I then place a piece of cardboard or zinc on the top of the stars and turn the false bottom upside down. The stars will be found to separate from the wood very easily, and may be left to dry on the zinc. The tray is then ready for another batch of stars.

The advantages of this plan are, that there is no trouble in getting the composition into a uniform, convenient shape and thickness; that the composition requires much less gum-water; and that, consequently, the process is a quicker and a cleaner one.

TAILED STARS.

15. The same plan may be adopted also for the making of _tailed_ stars, with a slight variation which I now proceed to describe. These stars are not moistened with plain gum-water, but with a mixture of gum-water and linseed-oil. The gum-water should be of the strength given above, and should be made _quite hot_ by placing the bottle which contains it in a jug of boiling water. When it is sufficiently hot, _to every 8 ounces of gum-water add 1 ounce of linseed-oil_. Shake the bottle till these are thoroughly mixed, _and no oil can be seen_. Use the moistening fluid, _while_ hot, in the same manner as directed above for brilliant stars. The following is the composition for

TAILED STARS. Nitre 16 parts. Meal-powder 12 „ Antimony (sulphuret) 8 „ Fine charcoal 4½ „ Sulphur 4 „

If the above directions are carefully followed out, you will have some stars which are exceedingly beautiful in their effect, and by no means difficult to make. At its first appearance the star has nothing remarkable in it but the rapidity of its combustion. When this, however, is over, a kind of boiling lava is formed which remains red hot for a long time, and which, in its descent to the earth, takes the appearance of a glowing drop of golden fire, followed by a tail of sparks, remaining visible till it reaches the ground. I think the proportion of linseed-oil given above will not bear being altered without detriment to the performance of the stars. _If less oil is used, the stars assume their tailed form sooner, and disappear sooner; if more_, they will reach the earth before their principal and characteristic beauty is seen.

Both “brilliant” and “tailed stars” may be made in cubes whose sides are about a quarter of an inch. On account of the presence of the oil, “tailed stars” take a longer time to dry than “brilliant.” An advantage which they possess, besides that of superior beauty, is that they are much more sure of ignition than brilliant stars.

I may as well mention here that a tray for forming the stars, such as I have described above, and of the size given above, will contain about 8 or 9 ounces of composition at a time.

COLOURED STARS.

16. We now come to the very important subject of _coloured_ stars. These require considerable care in their preparation, the beauty of their performance depending entirely upon the _uniform fineness, the intimate union, and the dryness of their ingredients_. If you wish to make these coloured stars with any degree of satisfaction to yourself, keep the various preparations which enter into their composition _always ready for use_—that is, _in fine dry powder_, preserved in well-corked or stoppered bottles. There is one chemical salt which requires especial care in keeping, on account of its deliquescent properties—that is, of its tendency to attract moisture from the air; and unless this salt, which is _the nitrate of strontia_, be thoroughly free from moisture when used, it will produce no effect at all, except a needless waste of chemicals. I must therefore tell you that the formulas which I am about to give you will fail most entirely in your hands, unless you are very particular in this matter of dryness. Over and over again have I been led to condemn formulas for coloured stars and fires as useless or imperfect, for the sole reason that I did not then know how their ingredients were to be handled, and what care was necessary for the production of their intended effect.

In the first place I strongly recommend you to attempt to make no coloured stars _for rockets, except such as are made in the pill-box cases_, of which I have spoken before. These pill-boxes are made in the following manner:—Procure a piece of _straight_ iron rod, 12 inches long, and from three-eighths to half-an-inch in size; the usual size for this “former” is about seven-sixteenths of an inch. Now cut some cartridge paper into strips about 8 inches wide, and from 9 to 10 inches long; paste these strips all over, and roll them round the iron rod closely and neatly. When this is done, remove the case thus formed from the rod without tearing or breaking it, and set it aside to dry. When dry it will be very hard and stiff. It can then be cut, by means of a very sharp knife, into little lengths of half-an-inch each. These lengths are the open pill-boxes, into which your composition is to be rammed for _coloured rocket stars_.

In order to accomplish the filling of these cases with the least amount of trouble, procure a piece of stick, of a convenient length, and of such a size round that it will pass _easily_ into the pill-boxes. Next take a small piece of quick-match, about 1½ inch long, and pass it through the pill-box in such a manner that it may project beyond each end about half-an-inch (see Fig. 31). You will be able to steady the pill-box while filling it by holding it by these two ends of quick-match. The composition pressed into these boxes is always slightly moistened; and by this means, when once dry, will not be liable to be shaken out again. In making, however, any trials of your coloured star compositions _for your own satisfaction_ before making a large batch of stars, you had better press the composition in _dry_; by this means you will be able to see at once what their performance is worth.

The fluid that I employ for moistening these coloured compositions is a solution of shellac in methylated spirits of wine. As shellac enters into the composition of many of these colours, it will not be necessary to make your solution a strong one. It should be of the thickness of the ordinary spirit varnishes, such as photographers use for coating their negative pictures. The exact strength is not a matter of any great importance, as long as you do not make the solution too rich in shellac; for by doing this you will impair the purity of your colour to some extent.

Remember that you must make these compositions _wet_. A very slight moistening is sufficient to make them _bind_ well when pressed into their cases.

The first colour of which I shall speak will be the red, or crimson. It is in the preparation of this colour that you must be most careful about _dryness_.

CRIMSON STARS.

17. The composition which follows is, in my opinion, the best for

CRIMSON STARS. Chlorate of potash 24 parts Nitrate of strontia 32 „ Calomel 12 „ Sulphur 6 „ Shellac 6 „ Sulphide of copper 2 „ Charcoal (fine) 2 „

This composition gives a magnificent deep crimson when burnt _at night_. Do not be disappointed, if, in your experiments _in the day-time_, the colour should not appear very deep.

Remember that there are two kinds of colours in pyrotechny, and that beyond a certain point it is impossible to amalgamate their respective qualities. The first of these two kinds is the colour _which has a considerable depth of tint, but which has not much reflective or illuminative power_. The other kind is that _which has a very decided, but not so deep, tint, and which is capable of surrounding itself with a luminous atmosphere of colour during its combustion—in fact, which has great brilliancy and power of illuminating objects_. Now the _last_ of these two kinds is the proper one to be employed for star purposes. We should never desire to produce a shower of dead-looking stars, however intense their colour might be. It is also an ascertained fact that the colour of stars always _appears deeper when seen from a distance_. Do not then be disappointed, I repeat, if the colour appears somewhat weak when you are making a trial of your composition _just under your eyes in the day-time_.

Now, with regard to the crimson star composition above, remember that I only say that it is one that succeeds _in my hands_. You may, perhaps, think it too rapid in its combustion, in which case you can increase the proportion of calomel, or decrease that of the chlorate of potash. The calomel has the effect of deepening the colour, but at the same time of retarding the combustion, and of weakening the illuminative power. The shellac must be in as fine a powder as possible; it has the effect of producing a rich, thick flame, and also of rendering more sulphur unnecessary. It also enables the composition, after having been wetted with the above fluid, to harden into a mass tolerably impervious to moisture. The sulphide of copper is used for the purpose of giving a very slight bluish tint to the flame, and thereby of neutralising any yellow that might impair the purity of the crimson, arising from impurity of the chemicals.

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:—