Sec. II. Of Mandrils and Cylinders for forming Cartridges and Cases.

The rollers or rods, on which cartridges are formed, ought to be solid, and perfectly straight and round. Very dry, sound wood should be selected, and when turned, the rod should be perfectly cylindrical; one extremity being concave, and the other convex.

Mandrils may be made of copper, which is preferable to wood, as this is apt to warp and crack; and in both cases, should be longer than the cartridge, so as to be drawn out easily. They are of different lengths and diameters, according to their respective uses.

Sec. III. Of Rammers, Chargers, and Mallets.

The rammers which are used for compression, are cylindrical like the preceding. They have a head much larger in dimensions than the part that enters the tube. (See A, B, C, D, and E of Fig. 1. in the Plate). Besides being made of wood, which should be of the hardest kind, as lignum vitÆ, they may be formed of copper or brass. In this case, they are first cast of the requisite size and shape, and finished in a lathe. Wooden heads are sometimes put to them, but with little advantage; as they frequently split and require to be renewed.

The wooden rammer may be struck with metal; but when the rammer is of copper or brass, wooden mallets must be always employed.

We may here remark, that in charging rockets, it has been customary to employ several rammers. The first drift must be six diameters from the handle, and this, as well as all other rammers, ought to be a little thinner than the former, to prevent the tearing of the paper, when the charge is driven in. In the end of this rammer is a hole to fit over the piercer. (See B. Fig. 1.) The line marked on this rammer, as will be explained hereafter, when it appears at the top of the case, indicates that a second rammer must be used. This second rammer, from the handle, is four diameters, having a hole for the piercer, 1¹/₂ diameters long. (C. Fig. 1.) When the case is filled as high as the top of the piercer, a short and solid drift is used. (E. Fig. 1.).

Rammers must have a ferrule, or collar of brass at the bottom, to keep the wood from spreading, or splitting. With regard to the handles of the rammers, if their diameter be equal to the bore of the mould, and two diameters long, the proportion is a good one. The shorter they can be used, the better. The longer the drift, the less of course, will be the pressure on the composition, by the blow given by the mallet.

We may observe here, that rockets may either be driven over a piercer, or driven solid, and afterwards bored.

As much of the effect of rockets depends upon the manner they are driven, whether lightly or compactly, or uniformly throughout, circumstances which affect their quality; it is necessary, in using the rammer, to employ an equal force for driving the composition. The mallet, therefore, should be of a given weight; and a certain number of strokes with the same force, on each new charge, must be accurately followed, until the driving is completed; taking care, at the same time, that the rocket stands firm on a solid body.

Dry beech is the best wood for mallets. A writer very judiciously observes, in the Encyclopedia Britannica, (vol. xv, 695), that, if a person uses a mallet of a moderate size, in proportion to the rocket, according to his judgment, and if the rocket succeeds, he may depend on the rest, by using the same mallet; yet it will be necessary, that cases of different sorts, be driven with mallets of different sizes. In all cases, under one ounce, the charge may be rammed with an ounce mallet.

There is an advantage, also, by having the handle of the mallet turned out of the same piece as the head, and made in a cylindrical form. If their dimensions are regulated by the diameters of the rockets; then, for example, if the thickness of the head be three diameters, and its length four, the length of the handle will be five diameters, whose thickness must be in proportion to the hand.

Bigot (Artifice de Guerre, p. 118) speaking of the flying fuses, or sky-rockets, observes, that the mallet used for driving the composition, is proportionably large, according to the rockets, and that it is five inches in length, and four in breadth, when the diameter of the rocket is from 12 to 18 lines. The mallets for larger rockets are stronger and heavier, and, in some instances, where a great force is required, as in driving war-rockets, a machine similar to the pile-engine, is used. See Congreve Rockets.

Sec. IV. Of Utensils necessary for constructing of Signal Rockets.

A detailed account of the tools used in making signal rockets, may be seen in Ruggeri, Pyrotechny, p. 143; but M. Bigot has enumerated them as follows:

• One mandril for forming the cartridge, or case.
• One pair of curved compasses to determine the exterior diameter.
• Three conical mandrils. (See fig. 3, plate.)
• One solid, or massive cylinder.
• One mould for garnishing.
• Two moulds for the capitals, or heads, one of which is for the rockets with, and the other for the rockets without, the garnish, or furniture.
• One piercer and block (See plate, fig. 1, I & H.)
• One scoop.
• One punch.
• One mallet.
• One press.
• One large knife.
• One pair of scissors.

All the wooden utensils ought to be made of hard and sound wood, without knots. The rammers should be furnished with rings or ferrules, and the first bored with a hole of sufficient length to receive the piercer. The second should be bored deep enough to receive two-thirds of the piercer, and the third, to receive one-third, while the fourth should be solid. These rammers are all furnished with heads. (See section iii.)

Sec. V. Of the Rolling, or Plane Board.

This board is furnished with a handle, and is used for rolling rocket cases, &c. and is of different dimensions, according to its application. It is made of hard wood, such as oak or walnut.

When the paper is wrapped round the mandril or former, the rolling board is used to compress the paper, and make it round and smooth.

Sec. VI. Of the Driver for charging large Rockets.

This contrivance is similar to a pile driver in construction; and, by means of a weight falling upon the rammer, the charge is sent home with great force. Its use is confined to the largest kind of rockets.

Sec. VII. Of Mortars and Pestles.

Mortars are employed for the pulverization of substances, and, according to their use, may be either of wood, marble, brass, or cast-iron, which last costs less than the others. Large mortars have covers, in order to confine the finer particles. The pestles should be of very hard wood; because, in that case, no danger would be apprehended of an explosion of the materials, an occurrence which might take place, if iron were used. This, however, depends on the substances submitted to the pestle.

Sec. VIII. Of the Choaker or Strangler.

The choaker is nothing more than a contrivance, usually made of rope, by which the closing of the end of the rocket is effected, so as to form a kind of cup or mouth.

Sec. IX. Of the Table and Sack for mealing Gunpowder.

This table may be either square or an octagon, and made of hard wood. There is a rim, a few inches high, raised round it, and a gutter at one end to allow the powder to pass out, when the operation is finished. See plate, fig. 7 and 8.

This mode of mealing powder is by no means to be preferred. (See Gunpowder.)

A sack is also used for crushing powder. It should be made of strong elastic leather, and sewed together in such a manner as to prevent the impalpable powder from passing through its seams. They are of an oblong shape, and contain from 20 to 25 pounds. Fifteen pounds are generally put in at a time. This method of crushing powder is preferred, as it is less liable to accidents. It is hardly necessary to add, that the bag is beaten with a cylindrical stick.

Sec. X. Of Sieves.

There are several kinds of sieve. The common sieve has neither a cover nor a receiver, and may be either formed of horse hair, or of brass or copper wire. It is necessary to have some sieves of a finer kind. For this purpose, silk and gauze are generally used. The cover is merely leather, fixed in a frame, which fits on the top. The receiver is formed nearly in the same manner, having a skin stretched over a frame, which fits on the under part of the sieve.

Sec. XI. Of the Paper Press.

A press, for the purpose of pressing paper, is formed of two pieces of wood, which are brought together by means of one, or several screws. This press is sometimes, though seldom, used. If pasteboard is made, when it cannot be had ready prepared, then the press is actually necessary. The intention is to unite the several sheets, which have been pasted, by using the pressure of the screw, and to remove any extraneous paste, so that the paper may have no inequalities on its surface. In lieu of the screw-press, heavy weights laid on the paper for several hours, will answer the same purpose.

CHAPTER II.

Preliminary operations in the preparation of fire-works, and observations on the preservation of gunpowder, and sundry manipulations.

Sec. I. Of the Workshop.

We have already noticed the principal furniture of a laboratory, and, therefore, can add nothing new on this head. There are, however, some utensils employed for particular works, which we may here describe.

In the disposition of the workshop, the tables, utensils, &c. are arranged, according as the judgment may dictate for convenience and use. Care must be taken to prevent the access of fire, and to prevent, as far as possible, the presence of moisture. Lanterns, if light is required, are always to be preferred; but the best manner of communicating light is through a window, placing the lights outside of the building, or apartment, as is done in powder mills. Other precautions may be necessary, which will readily suggest themselves.

In conducting the work, the workmen are to be so arranged, as that, while some are employed in the preliminary operations, others are making and finishing the preparations. The compositions may be ready prepared, and well preserved in jars or other vessels. This is named by the French, Cabinet de composition. It is a place, also, where the substances are weighed, and mixed.

Sec. II. Of the Magazine.

The magazine is a place of deposite for gunpowder, to preserve it from fire, and moisture. We have already mentioned the preservation of gunpowder in the article on that subject; but it may not be improper to offer some remarks, respecting the construction of magazines.

Authors differ in opinion, both in regard to their situation and construction; but they all agree, that they ought to be arched, and bomb-proof. The first powder magazines were made with gothic arches: Vauban constructed them in a semicircular form, to make them stronger. Their dimensions were, sixty feet long, within, and twenty-five broad. The foundations were eight or nine feet thick, and eight feet high, to the spring of the arch. The floors were two feet from the ground, for the purpose of keeping the magazine free from dampness.

It is observed, that the centres of semicircular arches will settle at the crown, and their sinking must break the cement. A remedy was applied for this inconvenience, by the arch of equilibration, as described in Hutton's work on bridges. As, in powder magazines, the ill effect of the breaking of the cement is particularly felt, Mr. Hutton proposed to find an arch of equilibration for them in particular, and to construct it, when the span is twenty feet, the pitch or height, ten, (which are the same dimensions as the semicircle), the inclined exterior walls at top, forming an angle of 113 degrees, and the height of their angular point, above the top of the arch, equal to seven feet.

A wall built round a magazine, gives it an additional security. The roof should be slated, or covered with lead or copper, and it ought to be furnished with a lightning rod, placed ten or fifteen yards from the building. The points of the rods may be either gilt, or of solid gold. Silver, however, is generally used; but, above all, platinum is to be preferred. The advantage of these points is, that they do not rust like iron, or become oxidized, an occurrence which would diminish their powers as conductors of the electric fluid.

To prevent the access of moisture, or rather to absorb it, some have recommended the inner walls to be covered with a composition of powdered coal, &c. Lining of magazines with sheet lead, appears to have some advantages.

St. Pierre observes, that a Prussian officer informed him, that, having remarked that vapour was attracted by lead, he had employed it for drying the atmosphere of a powder magazine, constructed under ground, in the throat of a bastion, rendered useless from its humidity. He ordered the concave ceiling of the arch to be lined with lead, where the gunpowder was deposited in barrels: the vapour of the wall collected in drops on the leaden roof, ran off, and left the gunpowder barrels perfectly dry.

Sec. III. Of the Driving or Ramming of Sky-rockets.

We purpose in the present article to give some general directions for the driving of rockets.

Rockets may be driven solid, or over a piercer. In the latter case, they must not have so much composition put in them at a time. The piercer, accompanying a greater part of the bore of the case, would cause the rammer to rise too high; so that the pressure of it would not be so great on the composition, nor would it be driven equally. For rockets rammed over a piercer, let the ladle, or copper scoop, hold as much composition, as, when driven, will raise the drift one-half the interior diameter of the case; and, for those driven solid, let it contain as much as will raise the drift one-half the exterior diameter of the case. Ladles are generally made to go easily into the case, and the length of the scoop is about one and a half of its own diameter.

The charge of rockets must always be driven one diameter above the piercer, and, on it, must be rammed, one-third of a diameter of clay; through the middle of which a small hole must be bored to the composition, so that, when the charge is burnt to the top, it may communicate its fire, through the hole, to the stars in the head. (See plate, fig. 14.) Great care must be taken to strike, with the mallet, with an equal force, giving the same number of strokes to each ladleful of composition; otherwise the rocket will not rise with a uniform motion, or burn equally and regularly, for which reason, they cannot carry a proper tail. It will break, in this case, before the rocket has ascended to its extreme height, where the rocket should break and disperse the stars, rain, or whatever is contained in the head. When in the act of ramming, the drift or driver must be kept constantly turning or moving; and when the hollow rammers are used, the composition is to be knocked out every now and then, or the piercer will split them. To a rocket of four ounces, give to each ladleful of charge, 16 strokes; to a rocket of 1 lb. 28; to a 2 pounder, 36; to a 4 pounder, 42; to a 6 pounder, 56. But rockets of a larger sort cannot be driven by hand, and must be rammed with a machine similar to a pile-driver.

The method of ramming wheel cases, or any other sort, in which the charge is driven solid, is much the same as that used for sky-rockets; for the same proportion may be observed in the ladle, and the same number of strokes given, according to their diameters, all cases being distinguished by their diameters. In this manner, a case, whose bore is equal to that of a rocket of four ounces, is called a four ounce case; and one which is equal, in bore, to an eight ounce rocket, an eight ounce case, &c. The method of ramming cases, without moulds, will answer for strong pasted cases, and save the expense of making so many moulds. In filling any case, it must be placed on a perpendicular block of wood, in order to keep it firm and solid; otherwise the composition would be rammed unequally.

When cases are to be filled without moulds, procure some nipples, made of brass or iron, in proportion to the cases, to screw or fix in the top of the driving block. When the nipple is fixed in, make, at about one and half inches from it, a square hole in the block, six inches deep, and one inch in diameter. Then have a piece of wood, six inches longer than the case intended to be filled, and two inches square. On one side of it, cut a groove, almost the length of the case, whose breadth and depth must be sufficient to cover near one-half the case. Then cut the other end, to fit the hole in the block; but take care to cut it, so that the groove may be at a proper distance from the nipple. This half mould being made, and fixed tight in the block, cut, in another piece of wood, nearly of the same length as the case, a groove of the same dimensions as that in the fixed piece. Then put the case on the nipple, and, with the cord, tie it, and the two half moulds together; and the case will be prepared for filling. The dimensions of the above half moulds are proportionable for cases of eight ounces; but they differ in size in proportion to the cases.

Sec. IV. Of the Boring of Rockets.

The machine, for boring rockets, is similar, in some respects, to a lathe. The rocket is confined in a box, and, by means of a wheel, which is made to turn a second one, an auger rammer is put in motion. The rammer must be of a size, proportionate to the rocket, and of the same diameter, as the top of the bore intended, and continue of that thickness, a little longer than the depth of the bore required. The thick end of each rammer must be made square, and all of the same size. The rammer is made to move backward, and forward, so that, after the rammer is marked three and a half diameters of the rocket, from the point, set the guide, allowing for the thickness of the front of the rocket box, and the neck and mouth of the rocket. When the rocket is fixed in the box, it must be pushed forward against the rammer, and, when the scoop of the rammer is full, draw the box back, and knock out the composition. A little oil is sometimes used, to prevent the friction from setting fire to the rocket. Having bored a number of rockets, taps must be used. These taps are similar to the common spicket. When employed, it is necessary to mark them three and a half diameters from the point, allowing for the thickness of the rocket's neck.

There are several contrivances for the boring of rockets. The operation is sometimes done, by confining the rocket in a box, and boring it with a borer, fixed in a brace, using, at the same time, a proper director. This brace is like the common brace, used by carpenters, or formed on that principle, and made of iron. The motion, given by the hand, performs the operation.

Sec. V. Of the Preservation of Steel or Iron Filings.

When treating of iron, we mentioned, that it has the property of oxidizing rapidly, when exposed to the air and moisture; and that its effects in fire-works, in that case, would be either destroyed, or considerably diminished. And even fire-works, in which iron enters as a component part, will, if kept long, lose some of their effect, in consequence of the change, which the iron suffers; for, instead of producing brilliant sparks, which is their intention, it would impart a dull red appearance.

Two methods are recommended for the preservation of iron. The one is to melt a portion of sulphur, and throw the filings into it, and afterwards to separate the extraneous sulphur. The other consists in wrapping them up in oiled paper. As to the first method, we may apprehend the effect of the sulphur, combining with some of the iron, instead of coating it, forming thereby a sulphuret, which, besides, is readily decomposed by the contact of air and moisture, producing sulphate of iron. The second method, of wrapping them in oil, or, in fact, covering them with oil, is certainly a greater preventive from rust, for where the oil is in contact, no oxidizement can take place.

There are several methods recommended to preserve iron-work from rusting. The use of paint and varnish for this purpose is familiar. In Sweden, they cover iron-work with a mixture of pitch, tar, and wood soot, which acquires a gloss, similar to that of varnish, and is said to prevent the oxidizement of the metal very effectually. Fat-oil varnish, mixed with four-fifths of rectified spirit of turpentine, has been recommended. It is applied with a brush, or sponge. Articles, varnished with this preparation, are said to retain their metallic brilliancy, and never contract any spots of rust. Another composition, for the same purpose, is highly recommended. It consists in applying a mixture of one pound of hogs' lard, free from salt, one ounce of camphor, two drachms of black lead in powder, and two drachms of dragon's blood. At Sheffield and Birmingham, sundry articles, made of steel and iron, are preserved from rust, when sent to foreign markets, by wrapping them in coarse brown paper, prepared first with oil.

Among the different preparations, recommended at various times to prevent iron from contracting rust, we may mention one, which has been used with success, and which gives a lead colour. It is nothing more than taking some litharge, and heating it in an iron pot, and scattering over it some sulphur. The litharge will change its colour, forming a kind of sulphuret of lead, which is then ground with drying oil, and applied like paint. We are told, that this preparation gets remarkably hard, and resists the weather more effectually than any other lead colour.

Sec. VI. Of the making of Wheels and other Works incombustible.

It is usual to give a coat of paint to the wood-work of wheels, &c. which are designed to carry a number of cases. To prevent their taking fire, paint, in some measure, has the effect. The following composition is recommended: Take brick dust, coal-ashes, and iron filings, of each an equal quantity, and mix them with a double size, made hot. Apply this to the wood, and when dry, give it another coat.

Several methods have been adopted for the same purpose; but wood may be made to resist, in a great degree, the action of fire, and rendered almost incombustible, by soaking it in a solution of the supersulphate of potassa and alumina, (alum), in sulphate of iron, (green vitriol), and in other salts, which are incombustible.

With respect to the use of alum as a preservative against fire, it is certain, that, although its use in this way is very ancient, it was not often recommended; for writers on the art of war, such, for example, as Anas, mentions the use of vinegar, in the following quotation from his Poliorcet. cap. 24: "Majus juverit, si prius ligna aceto linantur; nam a materia aceto illita, ignis abstinet."

The use of alum, to prevent substances from taking fire, is not a new invention; notwithstanding we find it recommended in modern works, not only for wood, but also for paper, and linen and cotton dresses, &c. Aulus Gellius relates, that Archelaus, one of the generals of Mithridates, washed over a wooden tower with a solution of alum, and thereby rendered it so much proof against fire, that all Sylla's attempts to set it in flames proved abortive.

A writer in the Anthologia Hibernica, vol. iii, for 1794, observes, that the use of alum to prevent the action of fire, on wood, or other combustible bodies, is not new, and those, who lay claim, are not entitled to originality on that head.

Another mode to prevent wood from taking fire may also be adopted. It consists in mixing together, one ounce of sulphur, one ounce of red ochre, and six ounces of green vitriol. The wood work is covered with joiners' glue, and the mixture is then put over it. This process is to be repeated three or four times, allowing the glue to dry before a new coat is applied.

There are several other preparations for the same purpose, not only for the covering of wood, but also paper. But M. Ruggeri is of opinion, that they cannot be depended upon, when used on paper; for the paper will, in part, be consumed. The formula for one of these compositions, is thus given by that gentleman: To a pound of flour, mix a handful of powdered alum, and add to it strong glue-water, and bring it to a proper consistence with clay. Flour and glue-water, mixed together, with the addition of a small quantity of muriate of soda, (common salt), is also recommended for the same purpose. Wood, steeped in a solution of common salt, so as to be thoroughly impregnated with it, is very difficult of combustion. In Persia, salt is used to prevent timber from the attack of worms. The practice of salting ship timber is highly recommended.

Wood, in fact, may be rendered incombustible by several processes, some of which we have given. Earl Stanhope, among others, made some interesting experiments on this subject.[23]

Having thus given some of the modes, usually adopted to render wood incombustible, or to prevent its taking fire so instantaneously, we purpose to add some remarks respecting the processes for colouring it. An excellent preservation against moisture, which communicates a colour at the same time, is formed of 12 lbs of rosin, 3 lbs of sulphur, and 12 pints of whale oil, melted and mixed with a sufficient quantity of red or yellow ochre, and applied by means of a brush. Pulverized black lead may be substituted for the ochre. Several coats of this mixture may be put on, allowing each coat to dry before another is applied. This composition is particularly well adapted for wheel work, &c. and for aquatic fire-works. Chaptal advises, for the same purpose, a mixture of equal parts of white turpentine, bees' wax, and maltha, or, in the place of maltha, coal tar. Wood, covered with three coats of this composition, and immersed for two years in water, was found to be quite dry. It would be well, however, to cover it with some of the preparation, to render wood incombustible.

With respect to the staining of wood of various colours, several preparations may be used. To communicate a green colour, a hot solution of acetate of copper may be used; or verdigris, alum, and vinegar, boiled together. A decoction of brazil wood, with alum and cream of tartar, will impart a red; indigo, dissolved in sulphuric acid, (liquid blue dye), a blue; a decoction of logwood, nut-galls, and copperas, a black; a solution of dragon's blood, or of alkanet wood, in turpentine, a mahogany colour, &c. The imitation of bronze on wood may be effected, by covering it first with isinglass size, then suffering it to dry, and putting on a coat of oil gold size, and covering it with bronze powder, a preparation sold for that purpose. A solution of aloes in spirits, which communicates a greenish-black, is a great preservative of wood against worms.

M. Ollivier (Archives des DÉcouvertes, v, p. 386) has given a variety of recipes for imitating bronze, stone, &c. He recommends the following for the imitation of ancient bronze, which may be applied to wood-work. Melt together 150 lbs of fine sand, 170 lbs of lead ore, (Galena), and 30 lbs of manganese, and add one-sixth part of brass. This compound is then pulverized. It is applied on the usual ground.

Black earth, as it is called, made of green earth, oxide of manganese, oxide of iron, and oxide of copper, is also recommended for covering wood-work. The composition for imitation marble, is 1 part of green earth, ¹/₂ a part of sand, and ¹/₈th of a part of bol. armen. By adding ¹/₁₄th part of yellow burnt copper, the colour will approach to green. The same composition, with ¹/₁₆th part of copper, and ¹/₃₂d iron, will give a black.

Sec. VII. Of the formation of Rocket, and other Cases.

The cases for rockets, as a general rule, are to be made 6¹/₂ times their exterior diameter in length; and all other cases, that are to be filled in moulds, must be as long as the moulds, within a half of the interior diameter. Rocket cases, from the smallest, to 4 or 6 pounds, are generally made of the strongest sort of cartridge paper, and rolled dry; but the large sort are made of pasted pasteboard. (See observations on that subject.) As it is very difficult to roll the ends of the cases quite even, the best way is to keep a pattern of the paper for the different kinds of cases. These patterns should be longer than the case they are designed for, and the number of sheets required should be marked, which will prevent any paper being cut to waste. Cut the paper of a proper size, and the last sheet for each case, with a slope at one end; so that when the cases are rolled, it may form a spiral line round the outside; and that this slope may always be the same, let the pattern be so formed for a constant guide. Before you begin to roll, fold down one end of the first sheet so far, as that the fold will go two or three times round the former; then, in the double edge, lay the former with its handle off the table, and after rolling two or three turns, lay the next sheet on that which is loose, and roll it all on.

The smoothing board, which is about twenty inches long, is now to be applied; and after rolling the paper three or four times, lay on, in the same manner, another sheet of paper, and smooth it in the same manner. This operation is to be repeated till the case is sufficiently thick. When the last sheet is rolled, we must observe, that the point of the slope is placed at the small end of the roller.

The case being made, the small end of the former is put in, to about one diameter of the end of the case, and the end piece is inserted within a little distance of the former. Then give the pinching cord one turn round the case, between the former and the end piece. At first, pull easy, and keep moving the case, which will make the neck smooth, and without large wrinkles. This operation is called by the French strangling, or choaking. When the cases are hard to choak, let each sheet of paper (except the first and last in that part where the neck is formed) be a little moistened with water. Immediately after you have struck the concave stroke, bind the neck of the case round with small twine, which must not be tied in a knot, but fastened with two or three hitches.

Having thus pinched and tied the case, so as not to give way, put it into the mould without its foot, and, with a small mallet, drive the former hard on the end piece, which will force the neck close and smooth. When this is done, cut the case to its proper length, allowing, from the neck to the edge of the mouth, half a diameter, which is equal to the height of the nipple. Then take out the former, and drive the case over the piercer with the long rammer, and the vent will be of a proper size.

Wheel cases are sometimes driven on a nipple, with a point to close the neck, and make the vent of the size required; which, in most cases, is generally ¹/₄th of their interior diameter. As it is very often difficult, when the cases are rolled, to draw the roller out, a hole must be made in its handle, and a pin, as a purchase, put in.

The machine for pinching cases consists of a treadle, which, when pressed hard with the foot, will act upon a cord, and draw it tight. The cord runs over a small pulley, and is fixed to an upright piece. It is wound once round the case, between the former and end piece; and when the cord is drawn, the case is brought together.

Cases are commonly rolled wet for wheels and fixed pieces; and when they are required to contain a great length of charge, the method of making these cases is thus: The paper must be cut as usual, except the last, which ought not to have a slope. Having it ready, paste each sheet on one side, and then fold down the first sheet as before directed; but be careful that the paste does not touch the upper side of the fold. If the roller be wetted, it will tear the paper in drawing it out. In pasting the last sheet, observe not to wet the last turn or two in that part where it is to be pinched; for if that part be damp, the pinching cord will stick to it, and tear the paper. Therefore, in choaking those cases, roll a bit of dry paper once round the case, before the pinching cord is used. This paper is to be taken off after the operation. The rolling board, and all other methods, according to the former directions for the rolling and pinching of cases, must be used for these, as well as other cases. See Encyclopedia Britannica, vol. xv, p. 692.

Morel, in a practical work, (TraitÉ Practique des Feux d'Artifice) speaking of rocket cases, observes, that the rule is, to give to their thickness, half the interior diameter, or half the diameter of the roller. If the roller, for instance, were half an inch, the case should be ¹/₄th of an inch in thickness. A rocket is divided into three equal parts; two for the interior diameter, and one for the thickness of the case.

As to the length of sky-rockets, it is regulated by the length of the piercer, if they are pierced in the charging. One-third more than this length is allowed for the choak, and the rest, of course, for the composition. With respect to other cases, Morel remarks, that the cases for turning pieces are usually six inches in length, and, for fixed pieces, seven and eight inches. The cases of Roman candles, are of the same thickness as those of rockets. In length they are, as well as the Mosaic candle, fifteen inches. They are choaked and cut.

Those of serpents are made with one or two cards, which are rolled upon a former of wood, or metal, ¹/₄th of an inch in diameter, and four inches in length. When made, the case measures three inches. Dry rolling is considered sufficient for these cases.

The fixed stars are made of common pasteboard, 3¹/₂ inches long, on a mandril, ¹/₂ an inch in diameter. They are pasted with ordinary paste, but mixed with clay, and choaked, and bound as usual.

Sec. VIII. Of Tourbillon Cases.

This kind of case is generally made 8 diameters long; but, if very large, seven will be sufficient. From four ounces to two pounds, will succeed perfectly, but, when larger, there is no certainty. They are best rolled wet with paste, and the last sheet must have a straight edge, so that the case may be all of a thickness. After rolling them in the same manner as wheel cases, pinch them close at one end; then, with a rammer, drive the ends down flat, and, afterwards, ram in about one-third of a diameter of dried clay. The diameter of the former for these cases, must be the same as for sky-rockets. Tourbillons are to be rammed in moulds, without a nipple, or in a mould without its foot. (Ency. Brit.)

Sec. IX. Of Balloon Cases, or Paper Shells.

First, prepare an oval former, turned out of smooth wood; then paste a quantity of brown, or cartridge paper, and let it lie until the paste is quite soaked through. This being done, rub the former with soap or grease, to prevent the paper from sticking to it. Next, lay the paper on in small slips, until you have made it one-third the thickness of the shell intended. Having this done, set it to dry; and when dry, cut it round the middle, and the two halves will easily come off: but, observe, when you cut, to leave about one inch not cut, which will make the halves join much better than if quite separated. When you have some ready to join, place the halves even together, and paste a slip of paper round the opening, to hold them together, and let them dry. Then lay on paper, all over as before, every where equally, excepting that end which goes downward in the mortar, which may be a little thicker than the rest; for that part, which receives the blow from the pounder in the chamber of the mortar, consequently requires the greatest strength.

When the shell is perfectly dry, burn a vent at the top, with an iron, large enough for the fuse. This method will answer for balloons from 4 inches ²/₅ths, to 8 inches in diameter; but, if they are larger, or required to be thrown to a great height, let the first shell be turned of elm, instead of being made of paper.

For balloons 4 inches ²/₅ths, let the former be 3 inches ¹/₈th, in diameter, and 5¹/₂ inches long. For a balloon of 5¹/₂ inches, the diameter of the former must be 4 inches, and 8 inches long. For a balloon of 8 inches, let the diameter of the form be 5 inches and ¹⁵/₁₆ths, and 11 inches ⁷/₈ths long. For a 10 inch balloon, let the form be 7 inches ³/₁₆ths, in diameter, and 14¹/₂ inches long. The thickness of a shell for a balloon of 4 inches ²/₅ths, must be ¹/₂ an inch. For a balloon of 5¹/₂ inches, let the thickness of the paper be ⁵/₈ths, of an inch; for an 8 inch balloon, ⁷/₈ths, of an inch; and for a ten inch balloon, 1 inch and ¹/₈th of an inch.

Shells, that are designed for stars only, may be made quite round, and the thinner they are at the opening, the better; for if they are too strong, the stars are apt to break at the busting of the shell. When making the shell, employ a pair of callipers, or a round gage; so that you may not lay the paper thicker in one place than other, and also that you may be able to know, when the shell is of a proper thickness. Balloons must always be made to go easy into the mortars. (See Encycl. Brit. Art. Balloon cases.)

Sect. X. Of Cases for Illumination Port-fires.

These must be made very thin, of paper, and rolled on formers; from 2 to ³/₈ths of an inch in diameter, and from 2 to 6 inches long: they are pinched close at one end, and left open at the other. When they are to be filled, put in but a little composition at a time, and ram it lightly, so as not to break the case. Three or four rounds of paper, with the last round pasted, will be sufficiently strong for these cases. (Ibid.)

Sect. XI. Of Cases and Moulds for Common Port-fires.

Common port-fires, are intended purposely to fire the works, their fire being very slow, and the heat of the flame so intense, that, if applied to rockets, leaders, &c. it will fire them immediately. When used, they are held in copper sockets, fixed in the end of a long stick. These sockets are made like port-crayons, only with a screw instead of a ring.

Port-fires, or lances of service of the French, may be made of any length, but are seldom more than 21 inches long.

The interior diameter of port-fire moulds should be ¹⁰/₁₆ths, of an inch, and the diameter of the former half an inch. The cases must be rolled wet with paste, and one end pinched or folded down. The moulds should be made of brass, and to take in 2 pieces lengthwise: when the case is in the two sides, they are held together by brass rings or hoops, which are made to fit over the outside. The bore of the mould must not be quite through, so that there will be no occasion for a foot. The French make the cases of five thicknesses of paper, and form the moulds upon rollers of ³/₈ths of an inch in diameter.

Port fire, according to the full acceptation of the term Porte-feu of the French, means a porter, or carrier of fire, and implies all sorts of fusÉes or matches, by which fire is communicated.

In a treatise on Military Fire-works, as taught at Strasburg in 1764, an extract of which was translated and published by order of the War Department in 1800, there are some observations on port-fires, which, as the mode of making them according to these directions appears to have been adopted, may be useful to notice in this place.

"Port-fires may be made in two ways. The first is made and beaten in a mould; the other simply rolled on a ramrod, and filled lying on the table.

"To make port-fires of the first kind, the mould must be made of dry wood, such as pear-tree, nut or box wood. The height of the mould is 13.85 inches; its diameter at the bottom, 3.2 inches; its diameter above, 2.13 inches; diameter of the hole or caliber, .62 inches; height of the base, 2.13 inches; its diameter, 3.2 inches.

"The base of the mould has in the middle a nob, which the turner leaves there, the diameter of which is equal to the whole of the mould, and one inch high, including the circle, which should be rounded like a hemisphere. There must be three rods, one of which, of hard wood to roll the cartridge upon; the two others of iron to ram down with. The one to roll upon, or the form, is to be of the length of the mould, exclusive of the handle, which is 3.2 inches longer. The diameter of this rod is .45 parts of an inch. The first, or greater one to charge with, is the same length with that to roll upon; the second is but half the length, and both are .44 parts of an inch in diameter.

"To make good cartridges, you must have good paper, well sized, cut according to the length of the rolling rod or form, which must be rolled very tightly round the form, so that the vacancy left may be exactly equal to the size of the mould, and that the paper should exactly fill the space between the form and the mould. Then the form is drawn out, after having tied it at the end with packthread. To fill it, it must be replaced in the mould. A cupful of composition is then put in, and five or six strokes given with the large ramrod. The ramrod is then withdrawn, and a new charge is put in, which is beaten like the first, until the cartridge is filled to the height of the mould. It is then drawn out, and primed with priming powder.

"The port-fire is filled with ease, in using a tunnel placed at the end of the cartouch, through which you pass the rod.

"Composition of Port-fires of the first kind.

Saltpetre	4	lbs.	2	oz.
Sulphur	1		12
Priming powder	0		12

"After having mixed these materials well together with the hand, and then with a rolling pin, you pass them through a hair sieve, and fill your wooden bowls.

"The second kind of Port-fires, are made in rolling strips of paper 3 inches wide, and 1.278 inches long, on a form of hard wood, about 14 inches long, and .35 parts of an inch in diameter. When about two-thirds of the paper is rolled, the remainder of it is to be pasted over with paste made of flour and glue. You then finish it, by passing your hand along the extremity of the pasted paper. Having finished the number required, you place them in the sun, or near a stove, and turn them from time to time, to prevent them from sticking together, or bending.

"Cartridges being well dried, you must fill them with the following composition. Fold the paper at one of the ends, and at the other, pour in the composition, placing your cartridge against the composition; and having placed it perpendicularly on the table, you give it several strokes, to drive down the composition. Then you take your iron rod, which is .53 parts of an inch longer than the one which you use to roll with, and a little less in thickness at the top. There should be a ring, that it may hang to the finger, and move the more easily. Having laid your cartridges on the table, you introduce the rod, and with it compress the composition. Having withdrawn it, more is put in, it is pressed again, and so on until entirely full. You will take care to press the last layer of the composition more than the other, to prevent its falling out by moving.

"The port-fire cartridges being finished, they are laid by for use, putting ten in a packet as before.

"Composition of Port-fires of the second kind.

Saltpetre	6	ounces.
Sulphur	2	do.
Priming powder	3	do.

"These three articles being mixed, you will put them in a wooden bowl, and moisten them with linseed oil, until you find the composition (being pressed well) is sufficiently hard."

It may be sufficient to observe, that the present improved process of making port-fires is preferable. (See Port-fires.)

Sec. XII. Of Pasteboard, and its Uses.

The pasteboard, used in pyrotechny, is made of fine white paper, by joining together five, and sometimes six, seven, and eight sheets of paper. That which is generally employed, is made of five sheets, and the other descriptions are employed for large cases. Sized paper is preferable, having more firmness than the other.

Pasteboard is made in the following way: A paste of flour is first prepared with hot water, and passed through a hair sieve, to separate the lumps. A sheet of paper is stretched upon a table, and covered, by means of a brush, with paste, and a sheet is then laid over it. This is compressed, and another coat of paste applied; then another sheet, then paste, and the number is added according to the thickness required. After five or more sheets are thus pasted together, a dry sheet is laid over, and the operation is repeated, till five more are joined. Then a dry sheet is put on, and the pasting is renewed. By this means, every five sheets are joined together, and the sheet, thus formed, is kept apart from the rest, by the dry sheet. A pile of pasteboard, consisting of some hundred sheets, may be made in this manner at one time. They are then put into a press for the space of five or six hours, by which they become firmly united, and all the extraneous paste is pressed out. When a press cannot be had, they may be put between boards, and heavy weights laid on. The pasteboard is then hung up in the air to dry, and again submitted to the press, to remove any inequalities, and to make it smooth.

When glazed paper is used for making pasteboard, we may employ, alternately, a sheet of brown paper. It is better, however, to use more of the glazed paper, than of the brown paper. Pasteboard of three thicknesses will be sufficient for most purposes. It is this kind, which is used for the heads of rockets.

Several kinds of paper, however, are used in fire-works. For small preparations, common white paper is sufficient. For port-fire cases, the common brown paper; for the joints, guarding places from fire, and covering tubes of communication, any kind of gray paper; and for covering marrons, the most indifferent kind may be used. Cartridge paper, as known by that name, may be used for a variety of purposes.

Paper may be rendered incombustible, or nearly so, by soaking it repeatedly in a strong solution of alum. In the Literary Journal of 1785, of Petersburg, there is a discovery mentioned of a kind of pasteboard, which neither fire can consume, nor water soften. It appears that alumina, and its salt (alum) were used in this preparation.

In the Journal des Arts et Manufactures, tom. ii, p. 205, is an account of the manufacture of pasteboard at Malmedy; and in the Transactions of the Society of Stockholm for 1785, is a description of the process for making the Swedish stone paper, which resists equally fire and water. Stone paper is manufactured in France, (Dictionnaire de l'Industrie, article Carton), by taking two parts of martial earth, (ochre, for instance), and mixing them with one part of animal oil, and two parts of vegetable matter, previously made into a pulp. The British Repository of Arts contains several specifications of patents for the preparation of the same paper.

Although paper may be rendered very difficult of combustion by the process already mentioned, that of soaking it in a strong solution of alum, yet to make a paper completely indestructible by fire, it must be made of amianthus. The process for manufacturing paper with this mineral, was announced in the Gazette de France in 1778. Professor Carbury received a medal for the invention.

Incombustible paper, for cartridges, ought to have the property, not of inflaming, but of simply carbonizing, when exposed to heat. M. Brugnatelli (Bulletin des Neustin) recommends the paper to be prepared with silicated alkali, commonly called the liquor of flints. Muriate of potassa, and supersulphate of alumina-and-potassa are both used for a similar purpose.

Paper made according to Brugnatelli's process, is merely carbonized by fire, and reduced to powder.

M. Hermbstaedt (Bulletin des DÉcouvertes,) observes, that paper, made with silicated liquor, attracts humidity, and proposes simply a solution of green vitriol, which has not that property.

Paper may be stained, or coloured, in a variety of ways, as is the case with the portable Chinese fire-works, that are brought to this country. Thus, a red paper may be formed by dipping it in a decoction of brazil wood and alum; yellow, by using fustic; a green, by a mixed bath of blue and yellow dye, or a solution of copper, &c. Coloured paper may be glazed with weak size, rubbing it afterwards with a polished stone.

The Chinese are in possession of several processes, as well for making, as for ornamenting paper. Their silver paper, which is sometimes put on their fire-works, is variously figured. The art is very simple. Two scruples of glue, and one scruple of alum, are dissolved in a pint of water. This is evaporated, and put on the paper, where they want it, and finally pulverized silvery talc (a magnesian stone) is sifted over it. It is then exposed to the sun, and the extraneous talc is brushed off. The glue, it is obvious, causes the talc to adhere.

The AbbÉ Raynal (Histoire Philosophique des deux Indes t. iii, p. 225) has some interesting facts respecting Chinese paper. Some useful remarks on paper hangings, paper for decorations, tapestry paper, &c. may be found in the Journal de Paris, 1785, the LycÉe des Arts 1795, and the Encyclopedie Method. Arts et Metiers, t. iv, p. 393. On the formation of paper vases, in imitation of Japan vases, consult the Dictionnaire de l'Industrie, article vases. The different patents, respecting paper, may be seen in the British Repertory of Arts, and the manufacture of paper generally, in Rees's Cyclopedia, and the Artist's Manual. The American improvements are noticed in the latter. Beckman (History of Inventions) has a variety of remarks on the same subject; and, in his article on paper hangings, &c. vol. ii, p. 161, says, that artists employed the silver-coloured glimmer (isinglass) for the covering of paper, and that the nuns of Reichtinstein ornamented with it, the images, which they made; as the nuns in France, and other catholic countries, ornamented their agni Dei, by strewing over them a shining kind of talc.

The quality of the paste, which is employed in making pasteboard, ought to be attended to. The flour should be of rye, and well boiled, after mixing it uniformly with cold water. Strong bookbinder's paste has the addition of a fourth, fifth, or sixth of the weight of the flour, of powdered alum. The patent paste is prepared by extracting starch from potatoes, in the usual manner, by means of cold water, and mixing it with mashed potatoes, after they have been boiled, and boiling the whole in water.

The Japanese cement, or rice-glue, may be advantageously used in many cases. It is formed by mixing rice flour intimately with cold water, and then boiling it very gently. It is beautifully white, and dries almost transparent. We are told, that it is preferable, in every respect, to the paste made with flour; and its strength is such, that paper, pasted together with it, will sooner separate in their own substance than at the joining.

The Chinese, to prevent accidents, and in order that they may fire their works without injury, and particularly their cases which are charged with brilliant fire, have a process, for preparing a paste of a different kind. With the exception of the clay, the same substances have been employed elsewhere for the like purpose. It consists of one pound of rye flour, boiled in water; to which is added, a small handful of common salt, the whole being thickened with finely pulverized white clay. The pasteboard, we are informed, which is made with this paste, is not only very solid, but not so susceptible of inflammation, as that prepared in the usual way.

A Chinese paste is announced in the Bulletin de la SociÉtÉ d'Encouragement, 1815, which is very economical, and used with success. It is made by mixing ten pounds of bullock's blood, with one pound of quicklime, and occasionally flour.

Sec. XIII. Of the Pulverization of Substances.

Various substances are employed either in grain, laminÆ, filings, or impalpable powder. When treating of nitre, sulphur, and charcoal, and other bodies, we mentioned the processes for reducing them to powder. It will be sufficient here to remark, that cannon powder, when it is converted into fine powder, takes the name of meal-powder; the conversion being effected, by beating it in a leather sack, already described, by rolling it upon the mealing-table, or by the action of a wooden pestle in a mortar. It is then passed through a fine sieve. The sack is said to be a preferable mode, as nearly the whole of it becomes pulverized. Saltpetre, sulphur, charcoal, antimony, &c. may be reduced to powder in a mortar of cast-iron, marble, or wood. The best method of pulverizing saltpetre is given under that article, which consists in boiling it in a copper, and stirring it continually at the end of the process. The best mode of pulverizing, or bringing cast-iron to a state of fineness, is mentioned in the article on Iron. Some of the metals, as iron, zinc, the alloy of copper and zinc, (brass,) &c. are brought to a sufficient fineness by the file. The filings, if so required, may be afterwards sifted. Zinc, when in small pieces, may be pulverized, by means of a steel mortar and pestle. It may be granulated, by suffering it to run, when melted, through an iron cullender into water. For the pulverization of camphor, see that article.

Sec. XIV. Of Mixtures.

All compositions for fire-works, are generally made at first in mortars, and the mixture is then finished by passing it through a sieve; it being returned to the sieve, and again sifted. This operation is sometimes repeated several times. Of all compositions, that for sky-rockets requires to be most intimately blended.

To receive the sifted matter, leather or parchment is used; but, in lieu of either, pasteboard, or several sheets of paper, cemented or glued together will answer. It is obvious, that, in preparing mixtures, of two, three, or four articles, they should not only be very fine, but uniformly and intimately mixed.

Several receivers, made by stitching leather over a rim, in the manner of a sieve, would be found very convenient; but wooden bowls, and copper basins, are generally used.

Some ingredients must be passed through a lawn sieve, after having been previously incorporated. A receiver, with a top, is the kind of sieve to be preferred. The composition for wheels, and common works, need not be so fine as for rockets. But in all fixed works, from which the fire is to play regularly, the ingredients must be very fine, and great care taken in mixing them together; and in those works, into the composition of which, iron and steel enter, the hands must neither touch them, nor moisture be suffered to come in contact. In either case, they would be apt to rust.

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