Chapter II: Part 2

In following the directions which I gave in my last paper for cutting up your imperial board and 70-lb. brown paper for rocket-cases, you will find that the case produced will not be a very stout one. Although I have made an excellent rocket in a case of such a thickness, you will, perhaps, find it advisable to use more paper and board, and prepare a thicker case. For this purpose cut your board in the manner that I have described before for your 70-lb. brown paper—that is, into _eight_ equal strips—and then cut each of your sheets of brown paper _lengthwise into four_ equal strips. By this plan you will be able to make very stout cases, which will not be at all liable to injury during ramming; and thus one sheet of board, with two of brown paper, will furnish eight ¼ lb. rocket-cases. You must bear in mind when choking them to contract the aperture till it is considerably smaller than you will eventually require it to be. The setting-down piece (fig. 4) has two uses: it is employed first in choking the case, and afterwards in driving or setting it down, when choked, over the steel spindle. The reason for driving the case thus down till the mouth is brought close to the nipple at the foot of the spindle is that the choke or aperture may thus be left of the proper size. This proper size is about two-fifths of the inner diameter of the case; and the aperture left immediately after choking should not be much more than one-fifth of the same inner diameter. The operation of “setting down” the cases is performed best, in my opinion, when they are perfectly dry and immediately before they are filled.

ROCKET COMPOSITION.

5. Now supposing your cases to be thoroughly dry and ready to be charged, the next thing that we must consider is the composition with which they are to be filled. Judging from the effect produced by rockets prepared by different makers, I should imagine that the formulas for their compositions are of almost endless variety. Some seem to prefer a very quick composition, which will raise the rocket to a great elevation in a very short time; others, one which will produce a large and rich tail of sparks not ascending so fast or so high. In my opinion, the mean between these two extremes is decidedly preferable: that which I aim at in rocket manufacture is to produce a very high, but not a very rapid, ascent; and when this my object has been properly gained, I have never had any fault to find with the tail of sparks which is thrown out. I may say, without any exaggeration, that I have experimented upon several hundreds of different compositions, varying first one ingredient and then another, increasing or decreasing them by very gradual steps, until I have come to the conclusion that the two following are the only ones worth retaining. But it must be remembered that it is not enough to have a good formula or two in order to be successful, for much will depend upon _the manner in which_, and _the care with which_, these are made up:—

No. 1.
Nitre 16 parts.
Sulphur 4 „
Charcoal 8 to 9 „

This, I believe, is a very old formula, and, provided the charcoal be properly prepared, may be found very useful and effective. I used this receipt for a long time, and thought it incapable of improvement, until, from a wish to try the effect of the addition of a little meal-powder, I came by chance upon the following, which I do not think can be surpassed:—

No. 2.
Nitre 16 parts.
Sulphur 3 „
Meal-powder 4 „
Charcoal 8 „

Now let me tell you that the success of rocket compositions depends upon two things—the intimate union of their ingredients, and the fineness or coarseness of the charcoal. Such charcoal as you can procure at a chemist’s ready pounded will be of no use whatever to you, for it is in far too fine a state of subdivision. You will require a much coarser charcoal for the most part, and one not of the same coarseness or fineness throughout. If you could make a mixture containing charcoal of three different degrees of fineness—the first moderately fine, the next in pieces of the size of grains of ordinary sporting gunpowder, and the third of the size of large poppy seeds—and take equal parts of each of these three you will find that you have a mixture very serviceable for rocket purposes. But you can procure of Mr. Darby, whom I have mentioned before, a mixed charcoal which will save you the trouble of sifting. I recommend you, however, to use no charcoal that will not pass readily through your 20-mesh mixer, for your object is not to have your charcoal in large pieces, but to have a certain proportion of it coarser than the rest. You will find that the larger your proportion of coarse charcoal is, the slower your composition will be, and, within certain limits, the more fine charcoal you employ, the quicker it will be. Now, as the sparks produced by coarse charcoal remain visible in the air much longer and are much larger, than those produced by fine charcoal, I think it advisable to employ a good proportion of the coarse and in order to make up the strength that the composition loses by this plan, I take a smaller proportion of sulphur, as you will see by comparing formulas Nos. 1 and 2, and at the same time add a certain quantity of meal-powder. All these ingredients may be procured of Mr. Darby. The mode of mixing them is as follows:—Weigh out your quantities of nitre, sulphur, and meal-powder, mix them well together, and pass them through your 40-mesh sifter. This you will have no difficulty in doing, because the condition in which you purchase them is one of fine powder; your meal-powder especially cannot be too finely sifted for this purpose. You will find it a great convenience to add to this mixture a few drops of methylated spirits of wine or gin—a very slight quantity will suffice to render it less dusty—but you must bear in mind that whenever either of these liquids is employed, the composition will be sure to rust the steel spindle around which it is driven, unless you take the precaution of rubbing it over with a little oil or grease after using and before putting it away. Next add your charcoal. Stir the whole together, and pass the mixture two or three times through your 20-mesh mixer; by this means it will be thoroughly incorporated and fit for use.

ROCKET RAMMING.

6. Now we come to the actual ramming of the rockets; and, unless you intend to be a great nuisance to your friends and neighbours, you had better not dream of performing this operation indoors, it being productive of much noise and jarring; and you will find that they will not take much interest in your pyrotechnic progress when they have been annoyed and deafened by your frantic efforts for their amusement. You had better choose, therefore, some place either out-of-doors, or in an outhouse, where you are not likely to be interrupted or interfered with; the outhouse, of course, will be preferable, because there you will not be exposed to wind and weather, the former of which, especially, is often a source of considerable inconvenience when working out-of-doors. But whatever place you decide upon, you must have a very solid block of some kind, which is better made either of wood or stone, and must be set upon, or let into, solid ground. I should think that you will find no difficulty in meeting with one, made of either of these materials, in any carpenter’s or builder’s yard; odd pieces of stone and timber which would answer your purpose may generally be procured for a few pence. The stone block which I use is about 12 + 8 + 8 inches. On your block I recommend you to put nothing but the wooden block into which your spindle is fixed. The composition which you are using should never be placed upon it, because it is sure to become to some extent unmixed by the concussion caused by the blows of your mallet, for the particles of any coarse ingredient which it contains will find their way to the surface. You will find it advisable to have your block, and the table on which your tools and composition are placed, of such a height from the ground that, in working, you need not stoop or put yourself into any uncomfortable attitude.

Next we have to consider what is the most convenient receptacle for your composition while your cases are being filled with it. I use a copper scoop capable of holding about 8 ounces of composition, made something like an open coal-scuttle in form, which I have always found very convenient, and which is represented in the annexed woodcut (fig. 17).

Fig. 17.
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You will next require a small ladle made of thin copper or brass, of such a size that it will take up just as much composition as you should put into your case at a time, and will admit of being passed into the case. By means of this you will be able to drive in the composition very uniformly, for by giving a certain number of blows of a certain power to each ladleful, you can be sure of an equal compression throughout the length of the case. Such a ladle Mr. Newman will supply with your rocket tools, of the right size for filling ¼ lb. cases.

I will now suppose you to be ready at the ramming-block, with all your tools about you, your composition ready, and your case driven firmly down over your spindle. I strongly recommend a slight moistening of the composition as directed above before you begin to ram it. Now, taking the longest of the drifts (fig. 13) in your left hand, insert into the case when the first ladleful of composition has been put in. You are not to suppose that by “a ladleful” I mean as much composition as can be heaped up upon the ladle or scoop, but as much as will lie within it after you have passed the drift over its surface, and have levelled the composition to the height of its sides. To this first ladleful of composition give _fourteen_ blows with the mallet: it is not necessary to exert much force in this operation, for the weight of the mallet will be nearly enough to do the work for you; and you will find that after each stroke the mallet will recoil with the blow to a point almost high enough to be the starting-point for the next stroke. Having given the proper number of blows, take another ladleful of composition, and when you have put it into the case, drive it down in the same manner as the former one with the same number of blows. Then for your third ladleful take the longest drift but one, which must be used for this and the following ladleful, giving to each of them _sixteen_ blows. Then take the shortest hollow drift, and use this for as many ladlefuls as will make the composition rise to the top of the steel spindle, giving eighteen blows to each of them. Then by inserting the short, solid drift, you will be able to measure the distance between the top of the spindle and the top of the case. When you have taken this measurement, make a mark, on _the outside_ of the case, which will show you how high the spindle rises on the inside. By adopting this plan, or any other that may occur to you as simple, you will always be able to ram the same quantity of solid composition above the spindle. This is really an important matter, and one on which depends mainly the beauty of your rocket’s performance when it reaches its greatest elevation in the air. There are great varieties of opinion as to what should be the quantity of composition rammed solid above the spindle, and it is a much more common matter to find too little than too much composition used for this purpose. The effect of using too little is, that the rocket does not fairly arrive at its turn before its stars or other decorations are thrown out. This, in my opinion, is a considerable fault; for it robs the rocket of a great deal of the elegance of its flight, and gives one the idea that it is in a hurry to get its work over. Nothing but actual experience and observation will enable any one to decide which he considers the proper quantity of solid composition. I consider the best length for this part of the rocket to be that of _the exterior diameter of the case_—that is, an inch or rather more for rockets of the ¼lb. size. Larger rockets, I have always found, do not require quite so much in proportion; smaller rockets rather more. You should give twenty blows with the mallet to each ladleful of this solid composition. I am well aware that this number of blows sounds like a great deal of hard work, but you may rest assured that these twenty blows, given as I have directed above, will occupy only five or six seconds of time, at the cost of very little exertion.

Having now completed the ramming of the composition into your case, you will next require some common potter’s clay in dry powder; this can be procured of Mr. Darby in a condition proper for use. Take half-a-ladleful of it, and ram it down very hard upon the top of the composition with the solid drift. This clay when thus compressed will form an end to your rocket nearly as hard as stone—not so hard, however, but that you can bore a hole through it about ⁵⁄₁₆ths of an inch in diameter, which will allow of the necessary connexion between the rammed composition and the stars or other contents of the head of your rocket. In the next place I will speak of the

PRIMING.

7. This may be done in two ways; for exhibition purposes I should merely put into the mouth of the rocket some meal-powder-paste made as follows:—Make a rather soft, but not too liquid paste, by moistening meal-powder with gum-water made of the strength of 2-oz. of gum-arabic to a pint of water. With the flattened end of a stick rub some of this paste into the cup formed at the choked end of the rocket, taking care that none of it _is left in the choke_ or narrow aperture at which the fire from the rocket has to find vent; for, if any should remain there, the rocket when fired is almost certain to burst. Any of the paste that happens to be forced into this aperture may easily be taken out afterwards by means of a piece of wire or stout pin.

Your rocket is now finished as far as its ascending power is concerned.

ROCKET POT.

Fig. 18.—Pot-former.
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Fig. 19.—Rocket pot.
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8. I will tell you my method of making the head, or _pot_ as it is termed, of the rocket. You must have a piece of hard wood turned of a shape like that indicated in the following woodcut (fig. 18). The straight part of this should be about 4 inches long, and a shade larger in diameter than the exterior of your rocket-case—that is, about 1⅛ inch in diameter, if you adopt the method of cutting up your imperial board and 70-lb. brown paper given in _this_ chapter. Now take some moderately thick brown paper, and cut it into strips about 5 inches in width and 8 in length; each of these strips will be long enough to go twice round the _pot-former_ described above. When you have pasted as much of each strip as will not lie actually against the former, roll it up straightly and pinch in one end; you will thus have made a cylinder of paper (fig. 19) closed at one end, the other end of which will fit nicely over the clay end of your rocket. This is the pot of the rocket, which is to contain your stars, rains, &c.

ROCKET CONES.

Fig. 20.—Cone-former.
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Fig. 21.—Paper for Cone.
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9. You will next require a turned wooden former on which you can make paper cones of such a size at their base that they can be neatly pasted on to the top of your pots—that is, the base of these cones should have the same diameter as the pots. Although such conical caps are by no means necessary, yet they are a very great assistance to the rocket in its ascent, enabling it to rise with much less resistance through the air. The cone-former is represented in the annexed woodcut (fig. 20). To make these cones upon it, cut out as many circular pieces of brown paper as you require, the semi-diameter of which must be slightly greater than the height of the cones that you have to make. Then cut or tear these circles into halves and paste them on one side. Now place the first half-circle upon the former, pasted side outwards, taking care that the apex of the cone beat the point marked A in fig. 21. Then fold the brown paper neatly round the cone-former, and when you have made it to sit as closely to it as possible, proceed in the same manner with the other half-circle, putting it upon the first, pasted side inwards. The paper cones thus made must next be covered with one thickness of thin paper cut large enough to extend ½ an inch or rather more beyond the open end of the cone, and this projecting part, when notched all round with your scissors, can be pasted down round the top of the rocket pot. When this is done the pot will present the appearance of annexed illustration (fig. 22).

Fig. 22.—Pot, with Conical Cap.
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ROCKET STARS.

10. When all the pasting that has been necessary in making the pots is thoroughly dry, the filling them with stars is all that remains to be done for the completion of the rocket. You will find that the ¼lb. rocket will carry an ounce of stars well. After weighing out your stars, then, into parcels of this weight, empty one of these parcels into each pot. You will next require some sort of powder to strew among the stars which shall have the effect of igniting them and at the same time of bursting the pot. I have always found meal-powder by itself to be too rapid in its explosion to convey the fire to all the stars; many of them are blown out of the pot, never taking fire at all. The mixture which I should recommend you to use is the following:—

Meal-powder 6 parts.
Fine charcoal 1 part.

Charcoal added to the meal-powder in the above proportion will render its combustion slow enough to light all the stars, without being too slow to burst the pot. Of this mixture take a ladleful (I mean the ladle which you use in filling your cases), and put it with the stars into the pot, which must now be securely glued over the clay end of the rocket-case.

ROCKET-STICK.

11. Lastly the rocket-_stick_ remains to be considered. This appendage is used for the purpose of keeping the mouth of the rocket _downwards_, so that if it move at all its motion must be an upward one. The rule for telling whether the stick be of the proper weight or not is the following:—After having tied it on to the rocket in the manner indicated in the page of illustrations, ascertain whether it will balance if laid across the finger about 2 inches from the mouth of the rocket. If the stick forms an exact counterpoise to the rocket at this point, it will answer your purpose very well. The length of the stick which I use for ¼lb. rockets is 4 feet, and its size about ⅜ × ½ inch. The best wood for these sticks is American pine. It is very light, and should be free from knots. You will be able to procure them much cheaper of Mr. Darby, and much more uniform in their make, than of any carpenter. In some old treatises upon pyrotechny you will find recommended a tapering rocket-stick, to the _large_ end of which the rocket is tied. I have never found any advantage which these sticks possess over those that are of one size throughout; and I think I may say that no professional pyrotechnist uses tapering rocket-sticks. On the annexed page of woodcuts (figs. 23 to 26) I have given you a sketch of the rings which I use, through which the rocket-stick must be passed, and from which the rocket is to be fired. These rings should be screwed into an upright post (fig. 27) standing 5 feet out of the ground; the upper ring near the top of the post, the lower about 3 feet from the ground. There is also a sketch (fig. 28) to show you how the rocket is to be suspended on this post.

I have stated above that there are _two_ ways of priming rockets; the one used for exhibition purposes I have already described. Rockets thus primed are fired by applying a lighted portfire to their mouth. The other method I have found very convenient when making trials either of rockets or of stars, for it enables you to get some distance from the rocket-post before the rocket rises, and consequently to gain a much better view of the object of your experiment. It is done in the following manner:—Paste or tie a piece of touch-paper round the mouth of the rocket which shall project an inch or rather more beyond the mouth. Then take a piece of uncased quick-match about 2½ inches long, and put it into the soul of the rocket, leaving so much of it outside the choke as can be twisted into the projecting part of the touch-paper. If this is done so as to leave a short twist of touch-paper beyond that part which contains the quick-match, you will gain a short interval of time between the moment of lighting the rocket and that of its ascent.

You can procure of Mr. Darby the cases _ready made_, and, in fact, anything employed in firework manufacture; but I strongly recommend you to learn to make the cases yourself, as you will then be not only much more independent, but also much more economical in your work.

Let me recapitulate a little, and add a few hints to remind you of certain points important in rocket manufacture.

Do not hurry over any part of the work, either the making the cases or the composition, or the ramming of the rockets.

In moistening your composition with spirits of wine or gin, be careful to add very little of the liquid, and to stir the composition about _very thoroughly_ until all the moisture that is present is very equally diffused.

Remember that the addition of nitre or meal-powder to your composition will render it more rapid in combustion; the addition of sulphur or charcoal more slow. By this means you can vary the strength of your rocket composition to any degree which proves successful or satisfactory in your hands.

By no means forget to bore a hole through the clay at the end of your rocket, and thus to form the communication with your stars.

Never allow your steel spindle to become rusty. Every coat of rust that you have to scour off from it diminishes the size of the spindle.

Remember that the work that is done neatest is always done best.

ROCKET STARS (How to Make).

12. By following a few simple directions for the manufacturing of these, you will be able to vary almost to any extent the heads of your rockets, and to produce combinations according to your taste and fancy.

The stars that are used as decorations to the different species of fireworks are of various kinds, sizes and shapes, according to the purpose for which they are intended.

1st. The ordinary rocket stars, which are called “brilliant” or “bright,” are made in small cubes. Their composition is moistened with gum-water, and while moist flattened to the thickness required. It is then scored or cut across with a knife, and allowed to dry. When dry it can be easily broken up into cubes at the places where it was divided by the knife. _Tailed_ stars are also made in the same way and of the same size.

2nd. Roman candle stars are small cylinders of composition made of a size proportioned to that of the case out of which they are to be thrown.

3rd. _Coloured_ rocket stars are made by driving the coloured composition, slightly moistened, into small cases, which go under the name of _pill-box cases_. If the star is to consist of one colour only, these pill-boxes are open at both ends, and a piece of quick-match is placed between the composition and the inside of the pill-box, and allowed to project about half-an-inch beyond each end of it. When fired, these stars burn at both ends at the same time, and so produce a great amount of fire in proportion to their size.

If it is required to make stars consisting of more than one colour (in which case they are called “changeable stars”), the pill-boxes are left open at one end only. The composition is thereby prevented from burning at more than one of its surfaces at a time. These stars generally contain _two_ colours; the pill-boxes are half-filled with one coloured composition and the remaining space filled with another. These changeable stars burn much longer than the others, and therefore produce a more beautiful effect; but being larger they require to be used in larger rockets, the _half-pound_ size being the smallest that is adapted for this purpose.

GOLDEN RAIN.

13. There is another and exceedingly beautiful decoration for rocket heads which is called golden rain. This is by no means a difficult thing to make. Some small paper cases are made, about 2 inches long and of the size of goosequills; these are filled with a sparkling composition and primed with wetted gunpowder. They are placed, mouth downwards, in the head of the rocket, and arranged in such a manner that they may _all_ be ignited. At the bursting of the rocket, they will describe a series of beautiful ringlets of sparkling fire.

I have now enumerated as many different kinds of stars, &c., as will provide you with the means of producing any amount of variety. I now come to the details of the manufacture of these decorations. We will begin with the ordinary

BRILLIANT STARS.

14. First, let me impress upon you the necessity of seeing that _all ingredients used in star compositions are in as fine a powder as possible_. You cannot have them too fine or too well incorporated and mixed. The following is the formula which I employ for the

COMMON BRILLIANT STARS.
Nitre 16 parts
Sulphur 8 „
Sulphuret of antimony 4 „
Meal-powder 3 „

Let all these ingredients be in fine powder, and, having carefully weighed out the quantities, mix them thoroughly. Next, take some gum-water of the strength previously mentioned—viz., two ounces of gum-arabic dissolved in a pint of warm water. Spread your star composition upon a piece of zinc plate or slate, and add to it a little of the gum-water at a time, taking care to stir the composition about _well_ till all the moisture is equally diffused through the whole. It is not necessary that this composition should be made _wet_, but only something like brown sugar in moistness, so that it will _bind well_ when pressed together. When you think this is sufficiently done, roll or press the composition into a flat shape like a thick pancake, and make it as square, or, at all events, as rectangular, as possible. Its thickness should be about _a quarter of an inch_. You will find a large spatula a very convenient tool in this operation, both for flattening the cake of composition and for getting it into a convenient shape. Now take your spatula, and with it score the composition across both ways, so that you have it divided into a number of little cubes, fig. 30.

It may then be set aside to dry in a warm place; it will be forty-eight hours before it is fit for use in summer, and about a week in winter. When dry you will have no trouble in separating the cubes at the marks left by the spatula.

Fig. 30.
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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.

Fig. 31.
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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:—

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.