A system of pyrotechny

The sabres made in Japan, according to Thunberg, are incomparable. Without hurting the edge, they can be made to cut through a nail at one blow.

The art of hardening steel by immersion in cold water is very old. Homer (Odyssia ix, 301,) says, that, when Ulysses bored out the eye of Polyphemus with a burning stake, it hissed in the same manner as water, when the smith immerses in it a piece of red-hot iron, in order to harden it. Sophocles, Salmasius, Pliny, Justin and others mention the use of water in hardening iron; but the most delicate articles of that metal were not quenched in water, but in oil. As to the opinion of the peculiar virtue of any particular water, for the purpose of hardening iron, which many have believed, it is altogether fallacious, although Vasari asserts, that the archduke Cosmo, in 1555, discovered a water, that would harden instruments, to cut, like the ancient tools, the hardest porphyry. The art of working porphyry, however, was known in every age. Beckman assures us, when treating of the processes of making steel, that the invention and art of converting bar iron into steel, by dipping it into other fused iron, and suffering it to remain there several hours, although ascribed to Reaumur, (Art de Convertir le Fer en Acier, p. 145), are mentioned by Agricola, Imperati, and others, as a thing well known and practised in their time.

Pliny, Diamachus, and other ancient writers mention various countries and places, which, in their time, produced excellent steel. The ferrum Indicum and Sericum were the dearest kinds. The former is the same as the ferrum candidum, a hundred talents of which were given, as a present, to Alexander in India.

Beckman thinks, that the ancient ferrum candidum is the same kind of steel still common in India, and known under the name of wootz; some pieces of which were sent from Bombay in 1795 to the Royal Society. Its silver coloured appearance, when polished, he thinks, may have given rise to the epithet of candidum.

Mr. Faraday of the Royal Institution has lately examined wootz, and imitated it very accurately. The experiments may be seen in Ure's Chemical Dictionary, article Iron. It appears that the presence of silex and alumina distinguishes this kind of steel from the English. Four hundred and sixty grains of wootz gave 0.3 of a grain of silex, and 0.6 of a grain of alumina. It is highly probable, that the much admired sabres of Damascus, are made from this steel.

A small portion of silver, melted with steel, improves the latter very considerably. One part of silver and five hundred parts of steel were melted together, and every part of the alloy formed, when tested, indicated silver. The alloy forged remarkably well, although very hard, and was pronounced to be superior to the very best steel. This excellence is undoubtedly owing to its combination with the silver, however small. The alloy has been repeatedly made, and with the same success. Various cutting tools have been made from it of the best quality. The silver is found to give a mechanical toughness to the steel.

Platinum and steel, equal parts by weight, form a beautiful alloy, which takes a fine polish, and does not tarnish. This alloy is said to make the best speculum. Steel, for edge tools, is improved by this metal. The proportions, which appear to be most proper, are from one to three per cent. An alloy of 10 platinum with 80 of steel, after exposure for many months, had not a speck on its surface. Would not this alloy, as it is not oxidized, be very useful for making points for lightning rods, in lieu of iron, gold, silver, or platinum alone? The experiment is worth a trial; for nothing adds more to the safety of a magazine, or building, against the effect of lightning, than a conductor.

Iron and carbon, it appears, are capable of uniting in different proportions; hence the variety of crude iron, and the different kinds of steel. When the carbon exceeds the iron, as in plumbago, or black lead, it forms a carburet. When the iron exceeds, such compounds are properly speaking sub-carburets; under which name, we may rank all the varieties of cast iron and steel.

The hardness of iron, according to the experiments of Mushet, (Phil. Mag. xiii, p. 138), increases with the proportion of charcoal, with which it combines, until the carbon amounts to about ¹/₆₀th of the whole mass. This is the maximum, the metal acquiring the colour of silver. More carbon diminishes the hardness, according to its quantity. The difference in iron, whether it be the cold-short, or hot-short iron, a matter of some consequence to the workers in this metal, was found to be owing to phosphoric acid in the cold-short, which exists with the iron. But the substance, called siderum by Bergman, is a phosphuret, and not a phosphate of iron.

We have gone into this subject more fully, on account of its importance, and intimate connection with the casting of guns, and the different qualities of iron. In fire-works, it will appear obvious, that the various properties exhibited by iron are owing to the iron and carbon, to the changes which they undergo, to the combustion which necessarily ensues, and to the production of oxide of iron, and carbonic acid gas; effects that invariably take place, whether cast iron or steel be used, provided it is exposed to the action of agents, under the same circumstances and conditions.

Sec. XLVII. Of Glass.

Glass, in the form of powder or dust, is used in fire-works. The pulverization of glass is easily performed. It may be done in an iron mortar, and passed though fine wire or brass sieves. It is used in the composition for wheels, in water balloons, cones, fire-pumps, slow white fire, &c.

Glass is nothing more than fused silica, made by exposing a mixture of silica and other substances to the action of a violent heat.

The quality of the glass depends on the proportion of silica, and the fluxes which are used in promoting its fusion; for the various kinds of glass, as white glass, green glass, bottle glass, &c. are all, in one respect, the same, though they differ in these particulars.

The glass of Saint-Gobin in France is made by fusing white sand, lime, soda, and broken inferior glass. The white goblet-glass is made of sand, potash, lime, and old glass; the quantity of potash is about fifty per cent. If green, or yellow, the colour is destroyed by the addition of black oxide of manganese; and hence that oxide is named glass makers' soap.

The common plate glass, for electrical machines, &c. is formed of sand, crude soda, old glass, and oxide of manganese. The bottle glass, made with the soda of marine plants, consists of sand, soda, common ashes, and old glass. Another bottle glass is made by melting common sand, black or yellow, with soda, wood-ashes, clay, and broken glass. It appears from the use of the substances which enter into, and compose, glass, that its quality is owing to the materials employed. The crystal or flint glass is a finer kind. The substances, with the proportions in which they are used, are the following:

To this is added, if the vitrification is not complete, some muriate of soda. Good glass, according to Pajot des Charmes, may be made by fusing equal parts of carbonate of lime, sand, and sulphate of soda. The glass is clear, solid, and of a pale yellow. Professor Scheweigger found, that the following proportions were the best:

Broad glass is made of a mixture of soap-boilers' waste, kelp, and sand. Two of waste, one of kelp, and one of sand are the proportions generally employed. Common bottle glass is usually made of waste and river sand, to which lime, and clay, and common salt are occasionally added.

The coloured glasses are produced by various metallic oxides. The colour and beauty of precious stones are thus imitated. These colours are communicated by sundry metallic preparations, as the following: The purple powder of Cassius, with oxide of manganese, will give a red or purple according to the proportions used; zaffre, an oxide of cobalt, a blue; a mixture of oxide of cobalt, muriate of silver, or glass of antimony, a green; and oxide of manganese, a violet, &c.

The basis of all artificial precious stones, is composed of what is called glass-paste, a compound of silica, potash, borax, red lead, and sometimes arsenic. These substances are melted together. The glass, which forms the body of the artificial gem, is pulverized, and the colouring substances are blended with it by sifting; and then the whole must be carefully fused, being left on the fire for from 24 to 30 hours, and cooled very slowly. The following proportions are used for this purpose:

Ruby. Paste 2880, oxide of manganese 72.

Emerald. Paste 4608, green oxide of copper 42, oxide of chrome 2.

Sapphire. Paste 4608, oxide of cobalt 68, fused for 30 hours.

Amethyst. Paste 4608, oxide of manganese 36, oxide of cobalt 24, purple of Cassius 1.

Beryl. Paste 3456, glass of antimony 24, oxide of cobalt 1¹/₂.

Styrian garnet, or ancient carbuncle. Paste 512, glass of antimony 256, Cassius purple 2, oxide of manganese 2.

The following recipes are given by M. Lancon:

Paste. Litharge 100, white sand 75, potash 10.

Emerald. Paste 9216, acetate of copper 72, peroxide of iron 1.5.

Amethyst. Paste 9216, oxide of manganese from 15 to 24, oxide of cobalt 1.

The ancient coloured glass has been much admired. The art was carried to a very great extent. Even in Pliny's time, the highest price was set upon glass entirely free from colour. He, as well as others, mentions that hyacinths and sapphires were imitated very exactly.

The emperor Adrian received as a present from an Egyptian priest, several glass cups richly ornamented with various coloured glass. Seneca speaks of the knowledge of Democritus in this art. Porta, Neri, and others, in modern times, have treated the subject in a more enlarged manner. Coloured glass was used for ornament; but Pollio relates, that Gallenius punished an impostor for selling to his wife a piece of glass for a jewel. In the Museum Victorium at Rome, are several ancient artificial gems, such as the chrysolite and emerald. What materials the ancients used for colouring glass is not known. Gmelin, however, observes, that it is probable they made use of iron, by which, he adds, not only all the shades of red, violet and yellow, but even a blue colour might be communicated. Cassius discovered the powder which bears his name. He was a physician, and resided at Lubec.[22] This powder was employed by the German artists. While noticing this subject, it may be proper to state, that Libavius (Alchemy, 1606,) gives a process for making ruby glass. Neri, (ars vitraria by Kunkel,) was acquainted with the gold-purple and its use. Glauber (Furnus Philosophicus, 1648) mentions the use, and gives the preparation of the powder. Kunkel made artificial rubies in great abundance, and a cup of ruby glass for the elector of Cologne. In 1679, he was inspector of the glass houses at Potsdam; and, in perfecting the art, he expended 1600 ducats, which the elector of Brandenburgh gave him for the purpose.

M. Brongniart has lately made many experiments on the subject of staining glass. The colours, however, are the same as we noticed. A green glass may be made by putting on one side of the glass a blue, and on the other a yellow. A black glass may be made by a mixture of blue with the oxides of manganese and iron. Painting on glass is an ancient art. When pieces of old painted glass are examined, they have always on one side a transparent red varnish burnt into them. The moderns, however, excel in this art.

Glass is not acted upon by the acids, except the fluoric or hydrofluoric. Hence the acid of Derbyshire spar, which is a fluate of lime, is used for etching on glass, in the same manner as nitric acid is, on copper. Fluoric acid, a compound of fluorine and hydrogen, is decomposed during this action, and is changed, by the union of its fluorine with silicon, into the silicated fluoric acid.

When a quantity of alkali is used just sufficient to fuse silica, glass is the result; but when the quantity is greater, as three or four to one, the fused mass is soluble in water, and then forms the silicated alkali, or liquor of flints. From this the silica is obtained in a pure state, by the addition of an acid.

Glass, when melted and dropped into water, assumes an oval form, with a slender projection, called a tail. This is called Prince Rupert's drop. If a small part of this tail be broken off, the whole bursts into powder, with a kind of explosion. The Bologna, or philosophical phial, is a small cylindrical vessel of glass, rounded at the bottom, but open at the upper end. It is made thick at the bottom, so as not to be easily broken; but if a pebble be dropped into it, it immediately cracks, and the whole falls into pieces. In both these, (the drop and the bottle,) the glass is unannealed. When the external part of glass is suddenly cooled, the inner part is kept, as it were, contracted. Now annealing, the process of tempering glass in an oven, renders the glass uniformly alike, and capable of sustaining the variations of temperature, without breaking. By a crack or fissure, the internal parts which remained in a state of tension, endeavour to recover the full state of expansion, and consequently the glass is rent asunder.

Sec. XLVIII. Glue and Isinglass.

Both glue and isinglass are animal products. They are used in fire-works, but always in the state of solution, as vehicles to mix up compositions in order to make them unite, and to preserve them from falling to powder. The quantity, however, is never large, or either would destroy the effect. The proportions are generally prescribed. A solution of glue is employed in the old process for refining saltpetre. See Nitre. In making priming paste, isinglass dissolved in brandy is sometimes used.

Glue and isinglass owe their adhesive quality to the presence of gelatin; the most remarkable property of which is, that it unites with, and precipitates the tanning principle from its solution in water. For this reason, the use of oak bark and other astringent substances, in the tanning of leather, is obvious, the gelatin of the hide or skin, uniting with the tannin and forming tanned leather. Gelatin exists in bones, muscles, tendons, ligaments, membranes and skins. Skins, especially those of old animals, furnish the best and strongest glue.

For the preparation of glue, the parings and offals of hides, pelts, and the hoofs and ears of horses, oxen, calves, sheep, &c. are first digested in lime-water to clean them; then steeped in fresh water, which is suffered to run off; and being previously inclosed in a strong linen bag, are boiled in a copper cauldron with pure water. The impurities are removed as they rise. To the solution, alum, or finely powdered lime, is added. It is then strained through baskets and allowed to settle; after which, the clear fluid is again boiled. When it becomes thick, or of a proper consistence, it is poured into moulds or frames, when it concretes into jelly. It is cut into pieces by a spade, and then into thin slices by means of wire, and finally dried on coarse net-work.

The goodness of glue is known by its brittleness, and equal degree of transparency, without black spots. It swells up in cold water, and becomes gelatinous, but does not dissolve. It is a mark of want of strength, when glue dissolves in cold water.

Size is also a gelatinous substance, and is colourless and transparent. Eel skins, vellum, parchment, &c. are used in its preparation. They are treated in the same manner as hides. Isinglass, or fish glue, is a finer kind of gelatin, obtained from the air bladder and sounds of different kinds of fish of the accipenser genus; as the sturio stellatus, huso ruthenses, &c. The bladder, when taken from the fish, is washed and stripped of its exterior membrane, and then cut lengthwise and formed into rolls, or cut into strips. Isinglass dissolves in water with more difficulty than glue. A coarser kind of fish glue is made from sea wolves, porpoises, sharks, cuttle fish, the sturgeon, &c. The head, tail, fins, &c. are boiled in water, and the solution evaporated. Isinglass is used for a variety of purposes, as the making of court plaster and size, the clarification of liquors, &c.

Isinglass is almost wholly gelatin. One hundred grains give ninety-eight of soluble matter.

Gelatin constitutes the greater part of the solid parts of animals, such as bone, ligament, muscle, membrane, skin, &c. and is always extracted by boiling them in water. We need hardly remark, that it constitutes the chief part of soup, which owes its nutritive qualities principally to its presence. The portable soup is nothing more than concrete gelatin, with other substances, as spices, salt, &c.; for it contains, in a small compass, the nutritive parts of beef, veal, and other animal substances, from which it may have been prepared.

Besides the use of water for extracting, or otherwise separating, the gelatin from bone, we may separate the phosphate of lime entirely from the latter, (as these two substances constitute the greater part of bone), by the action of dilute muriatic acid, which will dissolve the phosphate of lime, and leave the gelatin.

Sect. XLIX. Of Wood.

Of the kinds of wood, used for the preparation of coal, for the purpose of gunpowder, those should be preferred, which are light, and will give a tender charcoal. This subject was fully considered under that head.

But our intention, in noticing wood at this time, is, that it is employed in the composition of some fire-works in the form of saw-dusts, or raspings. Its use in fire-works may be considered, 1st, as producing a particular coloured flame: 2dly, as varying the character of the flame, and likewise the degree of the combustion; and 3dly, as communicating an agreeable odour along with other substances; as in odoriferous fire-works. To this, we may add its use in smoke-balls along with nitre and sulphur.

The raspings of wood are sometimes required to be extremely fine. This can only be done by employing sieves of different degrees of fineness. They should be preserved from the action of moisture.

In the composition of the new priming powder, of which chlorate of potassa is the basis, very fine raspings of a particular kind of wood are employed. So is also lycopodium for the same purpose.

By the distillation of wood, as in the process of carbonization in iron cylinders, we obtain some volatile products, the chief of which is the pyroligneous, now called the pyroacetic acid, while the ligneous fibre is converted into coal; but, in the combustion of wood, all the volatile products are expelled, some being consumed in the flame, and others, with some carbon, condensed in the form of soot, while the residue is an ash which furnishes common potash.

Ovid in his Metamorphoses, fable xvi, says—"Adomitis Athamanis aquis accendere lignum narratur; minimos cum luna recessit in orbes." This idea we know is groundless; for it is impossible, that wood, sprinkled with water, whether the waters of Athamanis, or any other, should be kindled when the moon is in the decrease, or at any time of the moon's age.

To prevent the action of fire on wood, marine salt, vitriol, and alum have all been used. Various ways of employing them have been adopted; but they do not absolutely prevent wood taking fire in an active heat. For the same purpose, (Coll. Academ. tome xi, p. 487,) a mixture of green vitriol, and quicklime is recommended, by which we form sulphate of lime and oxide of iron. The Journal de Paris of 1781 contains various processes. At Vienna, saline substances are employed.

The combustion of wood is the same, in all cases, in which oxygen is concerned; but the products in some particulars may vary. Hence saw-dust, when mixed with nitrate of potassa, and inflamed, will burn, and produce little or no smoke, because the combustion is rapid and perfect; but when employed with sulphur and nitre, it produces much smoke. Here the oxygen is furnished by the nitre, and carbonic acid gas is formed. The same thing takes place, when a mixture of saw-dust and nitre is used in artificial fire; and, according as the decomposition is more or less rapid, the combustion will be so likewise. The particular applications of saw-dust will be noticed hereafter.

With respect to lycopodium or puff ball and various species of agaric, or the medullary excrescences of trees, which are used in some preparations of artificial fire, we may observe, that the first is confined principally to theatrical fire-works, and the second to the preparation of spunk, or tinder, called also pyrotechnical sponge. See Pyrotechnical Sponge.

As to the substance usually called lightning wood, found in the hollow of the stumps of trees, and sometimes on the surface, which, from having lost its compactness and other characters of ligneous fibre, is called rotten wood, it is in fact the solid part of the wood in a state of decomposition, in consequence of which, it becomes a solar phosphorus. It appears to owe its phosphorescent property, i. e. its power of shining in the dark, to the previous absorption of light, and not, as some have suggested, to the presence of phosphorus, or the emission of any gaseous compound, which contains it. The process of animal putrefaction will produce such appearances, but, in this case, the cause is different.

Turf or peat, a substance found, and employed as fuel, in some countries, and found in boggy situations, is partially decomposed vegetable matter, consisting of a congeries of fibres or roots. But black mould is the result of a decomposition of vegetable substances, in which the ligneous fibre is carbonized, and mixed with earth. The formation of mould, however, is owing more to the decay of leaves &c. (See Coal.)

Dr. Shaw (Travels to the Holy Land) observes, that when they were either to boil or bake, camel's dung was their common fuel; which, after being exposed a day or two in the sun, catches fire like touch-wood; and burns as light as charcoal.

Sec. L. Of Linseed Oil.

Linseed, or flaxseed, oil is obtained by expression from flaxseed. It is a thick mucilaginous oil, when first extracted, called raw oil, and in this state, is seldom used. The preparation, it undergoes before it is used as drying oil for mixing with paints, is nothing more than boiling it with litharge, or some oxide of lead, which separates the mucilage, and unites with the oil. By this treatment, it acquires the property of drying with facility, when exposed to the atmosphere.

Linseed oil unites with great ease with oils, tallow, fat, wax, &c. Some of these compositions are used in fire-works. A preparation of pitch, mutton suet, and linseed oil is used, for instance, in preventing the access of moisture to fuses; and in military fire-works, it is employed in combination with pitch, rosin, mutton suet and turpentine for incendiary works. Wax, and tallow, we may here add, are also used in the preparations of similar works.

Sec. LI. Of Gum arabic, and Gum Tragacanth.

Gum arabic, which exudes from a tree that grows in Egypt and Arabia (Mimosa nilotica) when pure is transparent, and nearly colourless. There are several varieties of this gum; the gum senegal, for instance, which is of a reddish colour, and occurs in larger pieces. Other mucilaginous substances, the peach tree gum, the cherry tree gum, &c. which exist only in small quantities, are analogous to the gum of the Mimosa.

Gum arabic is brittle, and for that reason may be easily reduced to powder. It is readily dissolved in water, with which it forms mucilage. In this state, it is employed in fire-works, chiefly as a vehicle for the mixing of pastes, matches, &c.

Gum is a vegetable oxide, composed of carbon, hydrogen, and oxygen. It does not crystallize. It is precipitated by some metallic salts, as acetate of lead. It is insoluble in alcohol, which distinguishes it from resins. Nitric acid decomposes it, and changes it into the saclactic or mucous acid. With sugar, the same acid produces oxalic acid.

Gum tragacanth, or gum dragon, is the produce of a thorny shrub, which grows in Candia, and other islands of the Levant, called astragalus tragacantha. The gum obtained from this shrub has many properties in common with gum arabic, and is, therefore, used as a paste. It dissolves readily in boiling water; but is insoluble in alcohol, or ether.

It consists, almost entirely, of a peculiar vegetable principle, which is called cerasin by Dr. John. Cerasin has the adhesive qualities of gum arabic, but in a greater degree. It is said to constitute a part of the gummy matter, that exudes from the prunus cerasus, prunus avies, prunus domestica, &c.

Sec. LII. Of Cotton.

The soft down, which envelopes the seeds of different species of gossypium, or cotton plant, is the cotton of commerce. These plants are natives of warm climates. Cotton when bleached is perfectly white. It is extremely combustible, and burns with a clear lively flame. The ashes left behind contain potash.

Cotton is the substance, usually employed in making match rope, for the communication of fire. It has also other uses in pyrotechny. Cotton match is much used in fire-works for exhibition, not only for single cases, but also for a series of cases of artificial fire, either for fixed or moveable pieces; and serves to communicate fire, either singly, or from one case to another, or to the whole piece at one time. Matches, so used, are called leaders, and are generally confined in paper tubes.

Cotton is one of the best applications to recent burns. Applied to the part, it will, in a surprising manner, abate the violence of the pain, and remove the inflammation.

Cotton is soluble in alkaline ley. For some of the earths, it has a strong affinity, particularly alumina; as also for several metallic oxides, and tannin. The action of mordants, in dying of cotton-goods, depends on these affinities. Nitric acid converts it into oxalic acid.

Cotton wick for lamps, candles, &c. is rendered very inflammable by spirit of turpentine. By dipping the end of the wick in turpentine, the candle will inflame at once, the moment flame is applied. For candle-making, the wick is sometimes dipped in a solution of camphor in spirits, or in a melted mixture of camphor and wax. See Candle.

Sec. LIII. Of Bone and Ivory.

Bone, which is considered to be a combination of phosphate of lime, gelatinous matter, animal oil, &c. is used occasionally in fire-works. By destructive distillation, bones, or osseous matter, afford ammonia, Dippel's animal oil, &c.; and, when consumed by fire, leave a white ash, which is composed principally of phosphate of lime. Bone-ash is the result of the combustion of bone; for, while all the gelatinous substance, oil, &c. are burnt off, that, which composes the basis of bone, and which distinguishes it from gristle, remains in the form of ash. Bone-ash furnishes phosphorus by a certain process. See Phosphorus. Diluted muriatic acid will take up the phosphate of lime of bone and leave the gelatin. This mode is recommended for the separation of gelatin from bone.

Bones, when carbonized in the same manner as wood, furnish what is called bone-black, but commonly known by the name of ivory-black. It is nothing more than animal charcoal.

In Pyrotechny, bone, in the form of raspings, is employed to communicate a lustre to the flame of gunpowder; but, for this purpose, the most compact, and that, which contains the least gelatin, is usually employed. Hence ivory is preferred. Ivory, in the form of raspings, communicates to flame a bright silver colour; and, on that account, is preferred to all other kinds of bone. The compositions, into which it enters, will be mentioned in a subsequent part of the work.

Ivory is the tusk, or tooth of defence, of the male elephant, and is an intermediate substance between bone and horn, not capable of being softened by fire. The finest and whitest ivory comes from the island of Ceylon. The tooth of the sea-horse is said to approach to ivory, properly so called. It is, however, harder, and, for that reason, preferred by dentists for making artificial teeth. The coal of ivory is remarkably black; but the so called ivory-black, sold in the shops, is nothing else than bone-black.

Bone and ivory may be stained of various colours. One hundred parts of ivory contain,

One hundred parts of ox-bone gave

Berzelius, however, detected in bone-fluate of lime, muriate of soda, and uncombined soda. Albumen is most generally present. One hundred parts of bone are reduced by calcination to sixty-three. One hundred parts of human bone afforded Berzelius 81.9 phosphate of lime, 3 fluate of lime, 10 lime, 1.1 phosphate of magnesia, 2 soda, and 2 carbonic acid.

Sec. LIV. Of Galbanum.

Galbanum is a gum-resin, obtained from the bubon galbanum, a plant peculiar to Africa. It is at first a juicy fluid, which exudes when the plant is cut above the root, and hardens by exposure to the air. Alcohol dissolves about three-fifths of it. It contains some volatile oil.

The only instance we know of, in which galbanum has been used in fire-works, is in the composition of rain-fire, employed as an incendiary, before the present fire-stones were invented. The rain-fire, which may be found in the fourth part of this work, it is said, gave rise to the composition of fire-stone. There is no advantage, however, in using galbanum for this purpose; since pitch, tar, turpentine, and many other substances are more inflammable, and, therefore, better adapted for such compositions. We mention it merely because it was one of the ingredients in that once celebrated incendiary preparation, the fire-rain of Siemienowicz.

Sec. LV. Of Tow and Hemp.

In military fire-works, tow and hemp are much used, and principally for the preparation of incendiary works. Both tow and hemp are employed in forming match. Although old rope, &c. are used for immersion in the tourteaux, carcass, or fire-stone composition, which is readily imbibed, if the rope is untwisted and beaten; yet tow or hemp is a better material, and receives more of the composition. The manner of using it may be seen by referring to the composition for fire-stone. For very nice purposes, the tow or hemp should be well dressed. Flax is, therefore, to be preferred in such cases.

Sec. LVI. Of Blue Vitriol.

Different preparations of copper are used in fire-works, to communicate colour to the flame; and besides copper filings, brass filings, verdigris, and the oxides of copper, the sulphate of copper, or blue vitriol, has been employed. We may observe here, that there are three sub-species of this salt; the bisulphate, sulphate, and sub-sulphate, the first properly speaking being the blue vitriol of commerce.

The sulphate, although recommended in some of the old formulæ for coloured fire, is not, however, preferable to some other preparations of copper. The use and application of copper, and its preparations, will be seen in the article on coloured fire.

When sulphate of copper is heated, it is converted into a bluish-white powder. If the heat be increased, the acid is expelled, and the black oxide of copper remains. Before it is used, it is exposed to heat to expel the water of crystallization. It ought to be in the state of impalpable powder. It is composed of 33 acid, 32 oxide, and 35 water. It is decomposed by the alkalies and earths, the alkaline carbonates, borates, and phosphates, and several metallic salts.

The oxide may be obtained very readily from this salt, for the purpose of fire-works, by dissolving it in water, and adding a solution of caustic potassa; collecting the precipitate, and drying it in a moderate heat. This will expel the water that may be contained in it; as metallic precipitates, made in this way, are more or less in the state of hydrates.

When metallic copper is required, it may be obtained in fine powder, and very expeditiously, by immersing a plate of iron in a solution of any of the salts of copper, as the sulphate. It will precipitate on the iron, and gradually fall to the bottom of the vessel. This metallic copper will be found to be much more impalpable than the filings, however fine, and, for that reason, may be mixed more accurately with different substances.

Copper burns with a beautiful green flame, and deposites a loose greenish-gray oxide. The ammonia-oxalate of copper, of which there are three sub-species, burns with flame.

Sec. LVII. Of Nitrate of Copper.

This preparation of copper is used in some fire-works. It communicates a green colour to flame. When combined with carbonaceous substances, the combustion is vivid. This is owing to the decomposition of the nitric acid, (in the same manner as the acid of nitrate of potassa and other nitrates is decomposed), during which carbonic acid and deutoxide of azote are produced. Nitrate of copper has been more particularly recommended for the preparation of match stick, similar to that of M. Cadet, and of match rope. It is used in the same manner as the nitrate of lead. M. Proust used it in lieu of nitrate of lead when repeating some experiments of M. Born. It is more expensive than the acetate, or even the nitrate of lead. Its effect, however, is the same.

Nitrate of copper attracts the moisture of the atmosphere, and deliquesces. Acetate of lead, on the contrary, by exposure to the air gradually effloresces, and in time is decomposed. The preparations of lead, for that reason, are preferable to the nitrate of copper.

Nitrate of copper is formed by dissolving copper in nitric acid; and, when the acid is saturated, the requisite quantity of water may be added. The salt may be obtained in a dry state by evaporation; and, after being dissolved in water, the wood or rope may be soaked in it.

Dry nitrate of copper, wrapped up in tin-foil, will produce no action; but, if water be added, sufficient to moisten it, and then the foil closed tightly, combustion will take place. The water promotes chemical action by dissolving the nitrate of copper, which is then decomposed by the tin, and the quantity of caloric, put in a distributable state, is sufficient to inflame the tin. The details of the rationale will be given hereafter.

The ammonia-nitrate of copper is fulminating copper. The chlorate of copper is a deflagrating salt. Ammonia added to nitrate of copper, first separates an oxide, and then dissolves it. It is more than probable, that nitrate of ammonia causes the ammonia-nitrate to explode.

Sec. LVIII. Of Strontia.

The earth called strontia or strontian, is found abundantly in different parts of the world, in combination with carbonic and sulphuric acids. The carbonate of strontia or strontianite, effervesces with acids, and burns with a purple flame. It contains about 60 or 70 per cent. of earth. The sulphate of strontia, or celestine, contains about 57 of strontia.

When carbonate of strontia is mixed with charcoal powder, and exposed to a heat of 140° of Wedgwood's pyrometer, the carbonic acid will be expelled, and pure strontia remain. The earth may be obtained in a pure state, by dissolving the carbonate in nitric acid, and evaporating the solution until it crystallizes, and exposing the crystals, in a crucible, to a red heat, until the nitric acid is driven off. If the carbonate cannot be had, the sulphate may be employed. For this purpose, it is to be pulverized and mixed with an equal weight of carbonate of potassa, and boiled in water. The carbonate of strontia, thus obtained, which exists in the form of a powder, is to be treated with nitric acid as already described.

Strontia, like the other earths, is a compound body, having a metallic basis, called strontium, which, united with oxygen, forms the earth.

The specific gravity of strontia approaches that of barytes. Like pure barytes, it is soluble in water, forming strontia water. It requires rather more than 160 parts of water at 60° to dissolve it; but much less of boiling water.

The solution of strontia in water, when evaporated, will crystallize in thin, transparent, quadrangular plates, generally parallelograms, seldom exceeding a quarter of an inch in length. These crystals contain about 68 per cent. of water; and are soluble in little more than twice their weight of boiling water, and in 54.4 times their weight of water at 60°. When dissolved in alcohol, they give a blood-red colour to its flame. The solution of strontia changes vegetable blues to green. Strontia differs from barytes in being infusible, much less soluble, of a different form, weaker in its affinities, and not poisonous.

The metallic base of strontia, which was discovered by Sir H. Davy, in 1808, when exposed to the air, or when thrown into water, rapidly absorbs oxygen, and is converted into strontia.

As strontia communicates a red colour to flame, it has been used in certain compositions of artificial fire. The brilliant red fire, sometimes used in theatres, owes its colour to this earth. See Theatrical fire-works. Muriate and nitrate of strontia will give a red or purple colour to the flame of alcohol. See coloured flame of alcohol.

If a piece of cloth be dipped in a solution of muriate, nitrate, or acetate of strontia, or in strontia water, and then immersed in alcohol, it will burn with a red flame.

M. Fourcroy, (Système des Connaissances Chimiques, &c. tome iii,) mentions the use of nitrate and muriate of strontia, in artificial fire-works, for the purpose of communicating a red colour to the flame of combustible bodies. Since that time, the nitrate, in particular, has been recommended and used.

One of the characters of the salts of strontia, is, that they give a red flame to burning bodies; whereas the salts of barytes or of lime, used in the same manner, communicate a yellow flame.

The saline combinations of strontia were examined with particular attention by Dr. Hope. See Edinburg Philosoph. Transactions for 1790.

Nitrate of strontia may be formed by dissolving carbonate of strontia, or the sulphuret obtained by decomposing the sulphate by charcoal, in nitric acid, filtering the solution, evaporating it, and suffering it to crystallize.

Nitrate of strontia deflagrates on ignited coals. Dr. Hope pointed out, that if nitrate of strontia be exposed to a red heat, and a combustible substance be, at this time, brought in contact with it, a deflagration, with a very vivid red flame, will be produced. When a crystal of this salt is put into the wick of a candle, it communicates a beautiful purple flame. It does not deliquesce in the air, and, therefore, the compositions, into which it enters, cannot spoil on that account. Nicholson (Chemical Dictionary,) observes, that nitrate of strontia may be used in the art of pyrotechny. For this purpose, however, it is mixed with sulphur, chlorate of potassa, and sulphuret of antimony; and sometimes with the addition of sulphuret of arsenic and charcoal, as in the red fire for theatrical uses.

The muriate of strontia has similar properties. Davy first observed, that when strontia was heated in chlorine gas, it gave out oxygen gas, and a chloride of strontium was formed.

Muriate of strontia is formed very readily, by dissolving the carbonate or sulphuret of strontia in muriatic acid, and evaporating the solution in order to obtain crystals. These crystals are very soluble in water. They are soluble, also, in twenty-four times their weight of pure alcohol, at the temperature of 60°. This alcoholic solution, we remarked, burns with a fine purple colour. These crystals suffer no change when exposed to the air, except they be very moist; in which case, they deliquesce. When heated, they first undergo the watery fusion, and are then reduced to a white powder. Fourcroy recommends the muriate of strontia for fire-works.

Carbonate of strontia, when thrown in powder on burning coals, produces red sparks.

Acetate of strontia, another salt used in fire-works, is formed by dissolving strontia, or its carbonate, in acetic acid. It will crystallize. The crystals are not affected by exposure to the air. When heated, its acid is decomposed, as happens to all the other acetates.

Sec. LIX. Of Boracic Acid.

Borate of soda, or borax, is a salt, which has long been known, and is used chiefly in the arts as a flux for the fusion of bodies, and for soldering. Boracic acid is a compound body, consisting of a newly discovered substance, called boron, and oxygen. Homberg obtained the acid from borax in 1702, by distilling a mixture of borax, and sulphate of iron. He supposed that it was a product of the latter; and hence it was called the volatile narcotic salt of vitriol, or sedative salt.

Boracic acid forms two salts with soda; the borate, properly so called, and borax. It is supposed to be our borax, that Pliny mentions under the name crysocolla, so called by the ancients. Others, however, assert, that their crysocolla was nothing more than the rust of copper, triturated with urine. The impure borax in the East Indies, is called tincal. When borax is melted, and exposed for some time to heat, it loses its water, and is changed into what is known by the name of calcined borax.

The easiest process for obtaining boracic acid is to make a concentrated solution of borax in hot water, and add by degrees, sulphuric acid, which will unite with the soda; and, as the fluid cools, the boracic acid will separate in shining laminated crystals. No more acid should be added than is sufficient to make the solution slightly sour. The crystals are to be washed with cold water, and drained upon brown paper.

One of the principal characters of boracic acid is, that it is very soluble in alcohol, to the flame of which it communicates a green colour. Paper dipped in this solution, burns in the same manner.

In consequence of this property of imparting a green colour to flame, I made some experiments with it, for the purpose of preparing green fire; and found, that, by employing it in the proportion of one-eighth, the flame was always green, provided that the flame of the combustible used, was not tinged of any other colour. Nitre, charcoal, and boracic acid will give a green; also nitre, lamp oil, and boracic acid; nitre, alcohol, and boracic acid, along with charcoal; and chlorate of potassa, charcoal, and boracic acid, with or without the addition of alcohol. But, although boracic acid communicates a lively green, its expense will prevent its use in that way, especially as many other preparations, as those of copper, will have the same effect, and are more economical on account of their price. See the Coloured Flame of Alcohol, and Coloured Fire.

Oils, when assisted by heat, will dissolve boracic acid. In naphtha, it is very soluble. With oils, it yields fluid and solid products, which give a green colour to the flame of alcohol. It is not a combustible acid, but only imparts colour to the flame of combustible bodies.

Boron will unite with fluorine, the radical of fluoric acid. When one part of vitrified boracic acid, two of fluate of lime or fluor spar, and twelve of sulphuric acid are distilled, an acid gas will be obtained, called fluo-boric gas. For the properties of boron, consult Thenard's Traité de Chimie.

PART II.

INSTRUMENTS, TOOLS, AND UTENSILS.

CHAPTER I.

OF THE LABORATORY.

The laboratory for pyrotechny may consist of a building, furnished with furnaces, boilers, &c. for the preparation or refining of saltpetre, and other substances for use; but according to its present acceptation, it is a place where all kinds of fire-works are prepared, both for actual service and for exhibition; such as, besides the ordinary works for show, quick matches, fuses, port-fire, grape-shot, case-shot, carcasses, hand granades, cartridges, &c. It should have tables, benches, and closets, where the tools, paper, thread, &c. may be commodiously placed, and an adjoining room to contain a supply of materials for two days' work.

The chief artificer takes the weight of the materials made use of, attends to the weighing of the different substances, and sees that the mixtures are made properly, &c. He also keeps an account of the number and kinds of fire-works. The prepared fire-works ought to be removed daily to the magazine. If they are made up in the field, under a tent, (denominated the Laboratory tent,) they should be packed in barrels or in caissons.

Sec. I. Of Laboratory Tools and Utensils.

The following constitute the furniture and equipments of a laboratory:

• Copper rods, to load port fires, and the fuses of shells, howitzers, &c.
• Wooden formers, on which to roll the paper cases of the port fires.
• Wooden formers, to roll the cases of rockets.
• Balances, large and small, with weights, &c.
• Buckets to carry water.
• Boxes for loading priming tubes.
• Barrels with leather tops, that draw, in order to keep grained and meal gunpowder.
• Rods, or rammers for charging rockets.
• Brushes to wipe the tables and sweep the compositions together.
• Frames to dry priming tubes.
• Copper calibers to regulate the size of priming tubes.
• Penknives.
• Needles for piercing priming tubes in the direction of their length.
• Fuse drivers.
• Coopers' adzes.
• A copper kettle.
• Scissors for cloth and paper.
• Paper cutters.
• Priming wires.
• Skimmers for skimming the froth of boiling saltpetre.
• Funnels for charging port-fires, howitzers, shells, &c.
• Square ruler.
• Fuses for shells, &c. (or a lathe to make them.)
• Large and small wooden bowls.
• Small axes.
• Ladles for charging the fuses of shells, port-fires, &c.
• Mallets to hammer the fuses.
• Glue pots and brushes.
• Heavy mallets to beat the powder.
• Tin measures, of different sizes.
• Hand mortar.
• Foot rules.
• Rat-tail files to cleanse the interior of the reeds of priming tubes.
• Wooden rasps.
• Iron rulers, ¹/₂ foot long.
• Leather bags, in which gunpowder and charcoal are reduced to powder.
• Pocket saws.
• Pallet knives for saltpetre.
• Tables, small ones to mix the composition; large ones with a ledge to meal the powder on.
• Sieves, fine and common; of silk, and of hair.
• Fuse drawers.
• Tools for rolling cartridges.
• Gimblets of different sizes.

The materials required more particularly for military fire-works, are:

• Gunpowder.
• Saltpetre.
• Sulphur.
• Charcoal.
• Camphor.
• Beeswax.
• Glue, rosin.
• Cotton yarn for quick match.
• Brandy or other spirits.
• Gum arabic.
• Linseed oil.
• Spirits of turpentine.
• Pitch.
• Reeds or quills for priming fuses.
• Mutton tallow.
• Vinegar.
• Thread for tying quick match.
• Cartridge paper.
• Thread, tow and spun yarn, to make match rope.
• Cordage, to make tourteaux.
• Flour to make paste.

The characters used to express certain substances employed in fire-works, are the following: (James's Mil. Dict. p. 101.)