From these results, it appears, that, by the eprouvette of Darcy, the muriated powder, or that prepared with chlorate of potassa, gave a superiority of force of about one-fourth.

2nd. By the eprouvette of Regnier, which is repelled by the explosion, to a distance greater or less, measured by the degrees of the arc which it describes:

From which it results, that by the eprouvette of Regnier, the force of the powder of the oxymuriate is double that of the nitrate, or common powder.

M. Ruggieri is of opinion, that chlorate, or hyperoxymuriate of potassa may be employed with advantage in the composition of rockets, but we have not heard that it has been used. It is more powerful in its effects, and probably for this reason he recommended it. This salt, mixed with other substances, will produce the green fire of the palm-tree, in imitation of the Russian fire.

Chloric acid may be obtained in a separate state, by boiling the compound solution formed by passing chlorine gas through a solution of barytic earth, with phosphate of silver, which separates the muriatic acid. By evaporation, the chlorate of barytes will crystallize in fine rhomboidal prisms. When these crystals are dissolved in water, and diluted sulphuric acid added by degrees, an acid liquid will be obtained, which, if the sulphuric acid be added cautiously, will be found entirely free from the latter acid and barytes, and not affected by nitrate of silver. This is the chloric acid dissolved in water. Chloric acid unites with sundry bases. Combined with ammonia, it forms a fulminating salt, formerly described by M. Chenevix. This salt is formed, by mixing together carbonate of ammonia, and chlorate of lime. The carbonate of lime is then separated by the filter, and the clear liquid, holding the chlorate of ammonia in solution, is evaporated. Chlorate of ammonia is very soluble in water and alcohol, and decomposed by a moderate heat.

Chlorates, as the chlorate of potassa, are formed more readily in the manner already stated: viz. by saturating the base with chlorine, but in this case two salts are produced, the chlorate and hydrochlorate. Chloric acid has also been obtained in a separate state, from chlorate of potassa, by a process recommended by Mr. Wheeler.

Perchloric acid, composed of seven primes of oxygen and one of chlorine, is obtained from chlorate of potassa, treated in a particular manner. Three parts of sulphuric acid and one of chlorate of potassa, when heated, will give a saline mass, consisting of bisulphate of potassa, and perchlorate of potassa. Deutoxide of chlorine will be evolved. The perchlorate detonates feebly when triturated with sulphur.

Sec. IV. Sulphur.

Sulphur, or brimstone, is a principal ingredient in almost all the compositions of fire-works. It should, therefore, be pure. The flowers may be considered the purest kind of sulphur.

Sulphur is found native, either alone, or accompanying certain minerals, such as gypsum, rock-salt, marl, and clay, as in Switzerland, Poland, and Sicily. In the neighbourhood of salt-springs, it is also found; and frequently in water, in combination with hydrogen, forming the natural hepatic waters. It is also found on the surface of the earth, as in Siberia. Volcanic sulphur, or that which occurs in the fissures and cavities of lava, near the craters of volcanoes, is very common.

Solfatere, Sicily, the Roman states, Guadaloupe, and Quito, in the Cordilleras, are most celebrated for native sulphur. It has been found in the United States, but in no quantity. We have a number of mineral springs, which deposite sulphur. The Clifton Springs of Ontario are of this kind. It occurs abundantly, in combination with hydrogen, as sulphuretted hydrogen gas, in various parts of the United States.

Native sulphur is abundant in the island of Java. It is obtained from the now almost extinct volcano, about sixty miles from the town of Batavia. At the bottom of the crater, there is said to lie many hundred tons of native sulphur. Silliman (Journal, vol. i, p. 58) observes, that it is in the crater of this volcano, that the celebrated lake of sulphuric acid exists, "and from which it flows down the mountain, and through the country below, a river of the same acid."

Sulphur, however, is usually obtained from pyrites or metallic sulphurets, by fusion and sublimation. It is usually denominated by the name of the place whence it comes. Hence we have the Italian and Sicilian sulphur; the crude, roche, or stone brimstone of Marseilles, &c.

The quantity of sulphur, which may be obtained from the galena, or sulphuret of lead, by sublimation, is considerable. Twenty-five per cent is the loss sustained in the reduction of the lead ore, which occurs so abundantly in the neighbourhood of St. Louis. When general, the then lieut. Pike, (Expeditions, &c. Appendix) interrogated Mr. Dubuque in 1805, respecting the quantity of lead obtained from those mines, a detailed account of which is given by Schoolcraft, he replied that the mineral would yield seventy-five per cent. of lead, and hence the twenty-five per cent. loss must be the sulphur, together with any foreign matter it may contain.

The experiments of M. Vauquelin, (Annales de Chimie, 1811) to determine the quantity of sulphur contained in some metallic sulphurets, show, at once, the proportion which may be obtained from those combinations. Thus he found, that sulphuret of copper contains 21.31 per cent of sulphur; sulphuret of tin, 14.1; sulphuret of lead, 13.77; sulphuret of silver, 12.73; sulphuret of iron, 22; sulphuret of antimony, 25; sulphuret of bismuth, 31.75; sulphuret of manganese, 74.5; and sulphuret of arsenic, 43.

Of native or prismatic sulphur, there are two species, the common and volcanic. The former is of two kinds, the compact and earthy.

Sulphur, says Hanway, (Travels, &c.) is dug at Baku on the western side of the Caspian sea. It is found in the neighbourhood of the celebrated naphtha springs, some of which form a mouth of 8 or 10 feet diameter.

Von Humboldt (Annales de Museum National) communicated to the French national institute, that he discovered, in the province of Quito, a bed composed of sulphur and quartz, in a mountain of mica slate, and also sulphur in primitive porphyry. Kirwan (Geological Essays, p. 143) observes, that sulphur promotes decomposition, by absorbing oxygen, while it is thus converted into vitriolic acid; but moisture is also requisite. He attributes, in the same manner, the decomposition of stones that contain pyrites.

As the sulphur, which occurs in commerce, is chiefly obtained from its native combinations, it may be proper to make some brief remarks on this head. Sulphur in the state of combination is abundantly met with, and in all countries. It is found in the state of sulphuric acid, in various salts, as gypsum, epsom salt, native alum, &c.; and united with metals, forming natural sulphurets, as in sulphuret of iron, or iron pyrites, sulphuret of copper, or copper pyrites, sulphuret of lead, or potter's lead ore, called also galena, sulphuret of antimony, or crude antimony, sulphuret of zinc, or blende, sulphuret of mercury, or cinnabar, sulphuret of arsenic, or orpiment, &c. In fact, it appears to be a general mineralizer. It is found also in some plants, and in animal substances.

Without detailing minutely the processes employed for extracting sulphur from its combinations, which may be seen in Thenard, (Traité de Chimie, tome i, p. 184) it will be sufficient to observe, that, in general, pyrites, both of iron and copper, are arranged in alternate layers in the form of a pyramid, and the roasting is continued for several months. Part of the sulphur is consumed, and part is sublimed, and is condensed and collected in hollows, in the upper part of the pyramid, whence it is removed several times a day. It is also obtained from pyrites, by a kind of distillation. They are reduced to coarse powder, and put into hollow iron cylinders, or retorts, where the sulphur is disengaged and melted, and thence runs into vessels of water. This process is employed in Saxony, where nine hundred pounds of pyrites will yield one hundred to one hundred and fifty pounds of sulphur, which is afterwards purified.

When melted and cast into wooden moulds, it forms the roll brimstone; and, by sublimation, conducted in large chambers, as we shall afterwards mention, it is converted into the flowers of sulphur. The residue of the sublimation is sulphur vivum, which is also used in fire-works. The roll brimstone is frequently adulterated.

In the island of Anglesea, it is obtained by the sublimation of the yellow copper ore. The operation is conducted in kilns, and the sulphur is conveyed by means of long horizontal flues, and collected in large chambers. As the United States furnish an abundance of martial pyrites, and also galena, sulphur might be manufactured in this country, and advantageously, especially from galena, which is very abundant in the neighbourhood of St. Louis. In the roasting of the ore, all the sulphur is now lost, tons of which might be collected.

For the purpose of gunpowder, the purer the sulphur, the better will be the powder; hence attention is always paid to this circumstance. M. Michel, one of the principal refiners of sulphur at Marseilles, has improved the process for purifying sulphur for the purpose of gunpowder. M. Libaw, connected likewise with the French national powder establishment, has furnished a very useful and important memoir on the same subject.

Two methods are proposed for the refining of sulphur, which we will briefly state, namely, fusion, and sublimation. The first is conducted in iron pots fixed in a furnace; and the sulphur, before it is thrown in, is beaten into small pieces with a mallet. This facilitates the fusion, and renders it more uniform. Small portions at a time are thrown into the boiler, and stirred frequently with a wooden spatula. This manipulation ought to be continued till the boiler is filled. The heat must be regulated so as not to inflame, or sublime the sulphur.

The sulphur of commerce is commonly of three different colours, viz: citron-yellow, deep yellow, and brownish-yellow. These colours depend on the different degrees of heat to which the sulphur was exposed, in its extraction. The operation of refining consists in conducting the fire in such a manner, as that the colour of the sulphur will assume a brilliant yellow, bordering on a green. We must, therefore, to produce this effect, operate on the sulphur according to its colour. For the green sulphur, as little heat has been used for its extraction, the fire may be left under the boiler until there is no more left to melt than the top. The sulphur of the yellow colour may be kept longer on the fire, which may be removed when the mass is melted three-fourths. The sulphur of a brown colour, being already much burnt, may be removed when the mass is melted one-half. If it is required to operate on all the varieties at the same time, in order to produce sulphur of a uniform colour, in that case we must fill the boiler one-half with the green sulphur, one-fourth with the yellow, and the remainder with the brown, and removing the fire when the yellow is almost wholly melted. The boiler is then covered with a lid. The fusion is completed by the heat of the mass. The light bodies then raise themselves to the surface, forming a black scum, which is removed, and the heavy bodies fall to the bottom. The boiler remains for four or five hours, uncovering it from time to time to take off the scum. The fluid part is removed, and is suffered to congeal, taking care not to disturb the deposite.

The second process of refining is by sublimation. This operation consists in subliming it in a close apparatus, which in sulphur refineries are boilers placed in brick work, and furnished with heads. These heads communicate by a pipe with a vaulted chamber, placed at some distance from the furnace. The chamber serves to collect the sulphur. There is usually a stone slab fixed between the chamber and the head. The chamber is furnished with one or two iron-plate valves. There is an opening in the head of each boiler, in order to renew the sulphur: it is closed very tight by a plate of iron. There is an opening also in the chamber, to admit a person, which is closed likewise by an iron plate. The heads are luted before the process is commenced.

By this process the sulphur is refined; for the pure part is sublimed, and the foreign substances remain in the pots. The product thus obtained is the ordinary flowers of sulphur. If the heat be moderate, the sublimation is more perfect. It is necessary at the same time that the temperature of the chamber should be low, otherwise the sulphur will melt, which frequently takes place. Coarse particles are separated from the flour, should they occur, by a sieve.

During the first part of the process, there is formed some sulphurous acid gas, which is not produced after the vapour of sulphur forms the atmosphere in the head. This is known to exist, by the acid taste of the sulphur, and its black colour.

Detonation very frequently takes place, and sulphurous acid gas is produced. In the sublimation of brimstone, about ten to eleven per cent. is the usual total loss, of which six or seven per cent. is residue. The acid may be separated from the sulphur by washing it in water, and afterwards drying it. It is then called the washed flowers of sulphur. (See Traité de l'Art de Fabriquer la Poudre à Canon, p. 153.) by MM. Bottée and Riffault, for a minute description of this process.

Sulphur undergoes no change by exposure to the air. It is insoluble in water. It breaks in the hand with a crackling noise. At 170 degrees it begins to evaporate, and when collected it is called sublimed, or flowers of sulphur. It melts at 218 degrees. When melted and poured into water, it forms the sulphurs for taking the impression of coin, &c. If melted, and cooled slowly, it will crystallize in the form of needles. It is soluble in different degrees in alcohol, ether, and oils. When sulphur is burnt very slowly in the open air, it unites with oxygen and forms sulphurous acid. This acid is used in bleaching. When mixed with nitre, and burnt in leaden chambers, it forms sulphuric acid, or oil of vitriol, by which process it combines with a larger quantity of oxygen. There is another compound called hyposulphurous acid, all the salts of which are inflammable and burn with a blue flame. Sulphur unites with the alkalies, earths, and metals. If the alkaline sulphurets be dissolved in water, and an acid added, the sulphur will precipitate of a white colour, known by the name of milk of sulphur. It is considered by some a hydrate of sulphur. The same preparation is made by subliming sulphur in a vessel containing the vapour of water. Sulphur unites with chlorine and iodine, forming chlorides, and iodides. With hydrogen, it forms the sulphuretted hydrogen, or hepatic gas, called also the hydrothionic and hydrosulphuric acid; with carbon, the sulphuret of carbon; and with nitre and charcoal, in the state of mixture, it constitutes gunpowder.

The motionless ignes fatui of Italy, which are seen nightly on the same spot, are attributed to the slow combustion of sulphur, emitted through clefts and apertures in the soil of that volcanic country; but the Will-with-the-Wisp, which moves in undulations, near the surface of the ground, in swampy situations, and where the putrefactive process is going on, originates in all probability from decaying vegetable and other matters, and the extrication of phosphorus. It is known that the acid of phosphorus is found in plants, and especially those that grow in marshy places, in turf, and several species of the white woods.

Mealing of Brimstone. What is termed the mealing of sulphur by fire-workers, is no other than reducing it, if it be the roll, to powder. Large mortars and pestles made of ebony, and other hard wood, and horizontal mills with brass wheels are used. The mealing table is used by artificers. It is generally made of elm, with a rim around its edge four or five inches high. One end is narrow, and furnished with a slider that runs in a groove, and forms part of the rim. After using as much of the powdered brimstone as is required, copper shovels being employed, the rest may be swept out at the slider. This table is also used for the mealing of gunpowder and saltpetre. The muller is generally made of ebony. After reducing it to powder, it is then passed through a lawn sieve, furnished with a cover.

As brimstone is frequently adulterated with different substances, it may be of importance to discover the fraud. We may remark, that, if it is pure, it will be taken up entirely by chlorine gas, or by using a solution of caustic potassa. The latter, however, cannot be depended on in all cases. But the best mode, is that of melting some of it in a ladle; if any residue remains, after the fumes have ceased, the presence of foreign substances may be inferred, for pure sulphur will sublime without leaving any residue. It is not unfrequently adulterated with common flour. There is another mode of determining the quality of sulphur, It should, if pure, be completely soluble in boiling oil of turpentine. If any residue remain, we may infer the presence of foreign substances, either vegetable, earthy, or metallic.

It is obvious, that if the brimstone is impure, the effect of it in fire-works will be imperfect. Flowers of sulphur, however, may be almost always depended on. In all artificial fire, in which sulphur forms a part, the flame is more clear, as the sulphur is pure.

Several modes are recommended for the separation of sulphur from charcoal, in gunpowder, which may be seen by referring to the analysis, or chemical examination of gunpowder.

Sulphur constitutes one of the ingredients, generally speaking, of incendiary compositions, used for military purposes, and, in such cases, is usually mixed with pitch, tar, saltpetre, and sometimes gunpowder. It is said to be one of the substances, which entered into the composition of the ancient and celebrated Greek fire; but the principal character of which, that of burning in water, was owing to the presence of camphor. This substance, associated with sulphur, pitch, and nitre, forms one of the most effective incendiaries of all military fire-works. For such purposes, it is hardly necessary to add, that the common roll brimstone is sufficiently pure.

As to the mode of preparing these works, the custom is to melt the resinous substances first, then to add the sulphur, and finally the saltpetre; and after the whole are melted and thoroughly mixed, to remove the pot from the fire, and add gradually the gunpowder. If a carcass is to be made, tow or hemp, or untwisted rope, is immersed in the composition while hot, and taken out and formed into a ball of the size required. Rope, treated in the same manner, with the same composition, will make a more active tourteaux than the common kind. (See Carcass and Tourteaux.)

All oils, whether expressed or essential, can dissolve sulphur. To make this solution, the oil must be poured on the sulphur, and sufficient heat applied to melt the substance. While the oil dissolves the sulphur, it acquires a reddish or brown colour, an acrid, disagreeable taste, and a strong fetid smell, somewhat hepatic, resembling that of oil with sulphuric acid.

Sec. V. Of Phosphorus.

We mention this substance, because it is used in some experiments, although not in extensive fire-works. It is a very inflammable substance, inflaming either by friction, or an increase of temperature. It produces a most brilliant fire, and when mixed with some substances, exhibits very pleasing phenomena. It usually comes to us in sticks, which must be constantly kept in water to prevent its inflammation. Phosphoric matches, phosphoric fire-bottles, &c. are made of it. These are made in various ways. Phosphorus and sulphur melted together in a small phial, forms the fire-bottle, or some add a portion of lime. A sulphur-match dipped in this mixture and gently rubbed, immediately inflames. They do not last any time, in consequence of the acidification of the phosphorus. Phosphoric tapers are usually made with a glass tube, on the breaking of which, it inflames. When rubbed upon a wall in a dark room, it appears very luminous. Dissolved in ether, and poured upon boiling water in the dark, the vapour as it ascends appears remarkably luminous, and has a pleasing effect. Dissolved in oil, as olive-oil, it forms the phosphorized oil, which may be rubbed on the face and hands without injury. This oil has the same appearance in the dark. The time of night may be known by the light it produces. When mixed with nitrate of silver, sulphuret of antimony, sulphur, chlorate of potassa, &c. and struck with a hammer, it produces an explosion more or less loud. A variety of explosive compounds may be made with it, but they must be used with great care.

When combined with hydrogen, it inflames spontaneously when brought in contact with atmospheric air. It inflames also in chlorine gas. It is supposed to be the cause of the ignes fatui, or Will-with-the-Wisp. The formation of phosphoretted hydrogen gas may be shown in a variety of ways, as the following: throw some pieces of phosphuret of lime into water, and bubbles of gas will rise, which will take fire on coming to the air; or, put into a flask some phosphorus, iron or zinc filings, water, and sulphuric acid, and the gas will be generated; or, introduce into a small retort, a solution of potassa, and a piece or two of phosphorus, and apply heat, immersing the beak of the retort in a basin of water, the gas will pass over, and inflame as it comes to the surface of the water. In all these experiments, the water is decomposed; its oxygen goes to a part of the phosphorus in the first experiment, and the hydrogen of the water then unites with another portion of phosphorus, which is then evolved; in the second experiment, the oxygen oxidizes the metal, and the hydrogen dissolves a part of the phosphorus; and in the third experiment, the phosphorus unites with the potassa, forming a phosphuret, which decomposes the water, the hydrogen of which passes off in combination with some of the phosphorus, forming the phosphuretted hydrogen gas.

The cause of the spontaneous combustion is, that the oxygen of the atmosphere unites with the hydrogen and the phosphorus, and forms water and phosphoric acid; the latter producing a beautiful corona as it rises in the air. The heat and light given out proceeds as well from the oxygen gas, as from the phosphuretted hydrogen gas. When saturated with oxygen, it is no longer inflammable.

There are some other experiments which can be made with this singular substance.

It was formerly obtained from urine, as that fluid contains some phosphoric salts. It is now prepared from bones. These are burnt to an ash, and diluted sulphuric acid is poured on it; the phosphoric acid it contains is then disengaged, and remains in the fluid. The sulphate of lime is then separated, the fluid boiled to dryness, and the dry mass is mixed with charcoal, and distilled in the open fire.

The phosphoric pencil, for writing on a wall, paper, &c. to be luminous in the dark, is nothing more than a bit of phosphorus put into a quill. It must be kept in water, and when used, frequently dipped in water, to prevent its taking fire.

The phosphoric stone of M. Bucholz, described in the Archives des Découvertes, ii, p. 109, is a phosphuret of magnesia, prepared by melting thirty grains of phosphorus in a small flask, and adding twenty or thirty grains of calcined magnesia. Although this process is given by Bucholz, yet, as it is difficult to prevent the inflammation of the phosphorus, the best mode would be to bring the vapour of phosphorus in contact with magnesia, in the same manner as in preparing phosphuret of lime.

The pyrophorus of Wurzer is nothing than a phosphuret of lime. It is prepared by taking two parts of pulverized quicklime, and one part of phosphorus; introducing them into a bottle, and covering it with three parts of quicklime, leaving one-third of the bottle empty; then putting the bottle into a crucible surrounded with sand, previously stopping the mouth with clay, and applying heat. Remove the phial when the phosphorus appears to sublime of a red colour. When the bottle is opened it becomes luminous, and brought out it inflames.

Phosphorus in the state of acidification, and united with lime, is found in abundance. Whole mountains in the province of Estremadura in Spain, are said to be composed of this combination. According to Mr. Bowles, this stone is whitish and tasteless, and affords a blue flame without smell when thrown upon burning coals. Mr. Proust observes, that it is a dense stone, not hard enough to strike fire with steel, and is found in strata, which always lie horizontally upon quartz, and which are intersected with veins of quartz. He adds, that it does not decrepitate on burning coals, but burns with a beautiful green light. This stone is the common phosphorite. It contains, according to Klaproth, 32.25 per cent. of phosphoric acid.

Several substances are known under the name of phosphorus, although they do not contain it, such as Baldwin's phosphorus, or ignited muriate of lime, Canton's phosphorus, or oyster-shells calcined with lime, and Bologna phosphorus, or calcined sulphate of barytes.

Sec. VI. Of Charcoal.

Charcoal performs an important part in all the various kinds of fire-works. The facility with which it decomposes nitric acid, when it is combined with salifiable bases, as with potassa in saltpetre, and its action in all cases wherein nitre is concerned, are sufficient examples of its effect.

Pure carbon is the diamond. It affords by combustion in oxygen gas, the same gas as common charcoal, when charcoal is burnt in oxygen, or in atmospheric air. This gas is carbonic acid, or fixed air. Charcoal has been considered a long time an oxide of carbon, and according to some, as Berthollet, a compound of carbon, hydrogen, and oxygen.

Charcoal is insoluble in water. It is not affected by the most violent heat, if confined in close vessels. It is an excellent conductor of electricity, but a bad conductor of heat. It is very indestructible; and, therefore, when wood is charred, it will remain a long time under ground without rotting. As an antiseptic, it is powerful. It will therefore prevent the putrefaction of bodies, and even recover tainted meat. As a preservative of water, for sea-voyages, it has been long known. The charring of water casks is designed for the same purpose. The quality of wine is said to be improved by having the casks previously charred. It possesses the property of absorbing gases, and to this property is ascribed its use as an antiseptic, and its disinfecting quality. To the distiller it is useful, as it destroys effectually the burnt or empyreumatic smell of liquor. When heated to eight hundred degrees in the open air, it burns. In oxygen gas the combustion is brilliant, forming in both instances carbonic acid gas, called also aerial acid, fixed air, mephitic air, and calcareous acid. This acid is formed in a variety of processes, and is carbon saturated with oxygen.

Carbon exists in various states of combination, and many of the compounds into which it enters are inflammable; hence carbonic acid is generated in the combustion of coal, oils, fat, &c. In the form of an acid, it is abundant in various stones, such as the calcareous carbonates, as chalk, marble, limestone, and calcareous spar, barolite, &c. all which effervesce with acids, the carbonic acid being liberated. When limestone is burnt, to obtain quicklime, the carbonic acid is disengaged, for the presence of this acid distinguishes limestone from pure lime. Carbonic acid is generated in various processes of nature as well as art. Hence it is produced in the respiration of animals, and is found in a gaseous state in wells, cellars, caverns, &c. It neither supports animal life, nor combustion. In mines it is called choke damp; and the Grotto del Cani, in the kingdom of Naples, has been long celebrated, on account of it. This cave is in the side of a mountain, near the lake Agnano, measuring not more than eighteen feet from its entrance to the inner extremity; where if a dog or other animal that holds down its head be thrust, it is killed by the gas. Some experiments were made in this cave with gunpowder, which see. Carbonic acid, during the formation of alcohol, in the vinous fermentation, is generated, and its production appears to be designed by nature to carry off the excess of carbon, which gives rise to that phenomenon called fermentation. When combined with water, it forms aerated water, and with alkalies and water, the aerated alkaline waters. Its union with bases forms salts called carbonates. Plants have the property of decomposing it, and in this respect nature has employed a mean of regenerating the atmosphere, on the purity of which depends, in an eminent degree, the very existence of animal life. The prime equivalent of carbonic acid is 2.75, and carbonic acid is composed of carbon 0.75 + 2.0 oxygen.

Carbonic acid may be decomposed when combined with a base, as lime, by phosphorus and heat, for charcoal and a phosphate of lime will be produced. But carbonic acid in the state of gas may be decomposed by potassium. Five grains of potassium will decompose three cubic inches of gas, and be converted into potassa, producing at the same time three-eighths of a grain of charcoal. If passed over a coil of fine iron wire heated to redness, in a porcelain tube, and the operation repeated, the iron will be oxidized, and the carbonic acid changed into carbonic oxide gas.

Charcoal will not burn in dry chlorine. It unites with a less proportion of oxygen, and forms carbonic oxide gas, which burns with a deep blue flame. This combination is formed by distilling in a red heat, a mixture of equal parts of iron filings and chalk. This gas mixed with chlorine gas, and exposed to the sun's rays, will unite with it, and form chlorocarbonic acid gas. Carbon unites with azote, and forms cyanogen, the base of Prussic acid. It unites likewise with hydrogen in two proportions, forming the hydroguret and the bihydroguret of carbon, both of which are carburetted hydrogen gases. The former is obtained by distilling a mixture of four parts of sulphuric acid, and one of alcohol. The gas is very inflammable, and burns with great splendour; and on that account may be used for exhibition, in an apparatus similar to that of Cartwright. (See Fire-works with Inflammable air.) It was called by the German chemists olefiant gas. The other species, called also the light carburetted hydrogen gas, may be obtained by agitating the mud at the bottom of stagnant pools; and by the distillation of moist charcoal, wood, pitcoal, pitch, or almost any animal or vegetable substance. The gas, used for gas-lights, is the same. It is usually obtained from pit coal. We may merely observe, that the gas used for that purpose, i. e. for illuminating streets, theatres, manufactures, &c. as obtained in the common method, is not altogether the bihydroguret of carbon; but, according to the experiments of Dr. Henry, a mixture of that gas with the hydroguret, and occasionally carbonic oxide.

Carbon enters into other combinations. It exists as a component part of gums, resins, sugar-starch, and other vegetable products, as the vegetable acids, its union with iron forms steel, a substance greatly used in the preparation of some fire-works, especially in some of the rains and stars, and in the composition of brilliant fire. (See Iron.)

As charcoal enters into the composition of gunpowder, and the effective force of powder depends considerably on the quality, as well as the proportion of charcoal, it is obvious for this purpose, it should be as pure as possible.

Carbon is always obtained from some of its combinations, as from pitch, tar, rosin, wood, and oil. Various processes are employed for this purpose. Thus, by the combustion of rosin and oil, as well as pitch, tar, turpentine, &c. a soot is formed that collects, called lampblack, which is nothing more than the carbon or charcoal. When pit-coal is charred in an oven, called a coke oven, all the bitumen and sulphur contained in it are disengaged, and a charcoal remains, called, however, coke. Wood, when charred is decomposed; all the volatile parts are disengaged with carburetted hydrogen gas, and the woody fibre is converted into coal. This coal is more or less dense according to the compactness of the wood. Hard woods furnish the most solid coal, and light woods on the contrary.

When the solid parts of animals, as bone, are charred, the volatile products, principally ammonia or volatile alkali, are dissipated, and there remains a substance called bone-black, improperly called, ivory black.

The carbonization of wood in the common way is well known: after it is cut to the lengths required, it is piled on the ground in a pyramidal form, and covered with sod and clay, leaving a place for the current of air, and the smoke. The wood is then set on fire, and when the whole is burnt to a coal the vents, &c. are closed with sod and clay.

Nicholson (Chemical Dictionary) observes, that in the forest of Benon, near Rochelle, great attention is paid to the manufacture, so that the charcoal made there fetches twenty-five or thirty per cent. more than any other. The wood is that of the black oak. It is taken from ten to fifteen years old, the trunk as well as the branches, cut into billets about four feet long, and not split. The largest pieces, however, seldom exceed six or seven inches in diameter. The end that rests on the ground is cut a little sloping, so as to touch it merely with an edge, and they are piled nearly upright, but never in more than one story. The wood is covered all over about four inches thick with dry grass or fern, before it is enclosed in the usual manner with clay; and when the wood is charred, half a barrel of water is thrown over the pile, and earth to the thickness of five or six inches is thrown on, after which it is left four-and-twenty hours to cool. The wood is always used in the year in which it is cut.

Turf or peat has been charred lately in France, it is said, by a peculiar process, and, according to the account given in Sonnini's Journal, is superior to wood for this purpose. Charcoal of turf kindles slower than that of wood, but emits more flame, and burns longer. It boiled a given quantity of water four times, while an equal weight of wood charcoal boiled the same quantity but once. In a goldsmith's furnace, it fused eleven ounces of gold in eight minutes, while wood charcoal required sixteen. The malleability of the gold, too, was preserved in the former instance, but not in the latter. Iron heated red-hot by it, in a forge, was rendered more malleable.

In charring wood it has been conjectured, that a portion of it is sometimes converted into a pyrophorus, and that the explosions that happen in powder-mills are sometimes owing to this.

Bartholdi supposes, that such explosions are owing to the formation of phosphoretted hydrogen gas, while others attribute them to the absorption of oxygen, by the hydrogen contained in the coal, and the consequent evolution of free caloric. Percussion, which necessarily takes place in mixing the materials of gunpowder by stampers, no doubt accelerates the combustion. The addition of water, and having the charcoal previously pulverized, will prevent such accidents. (See Gunpowder.)

Coal prepared in the manner above stated, is liable to many foreign admixtures, nor can the process be so well regulated as to produce coal of a uniform quality throughout. The present improved process has many advantages, as experience has proved. It consists in charring the wood in confined vessels, made of iron. These are usually cylindrical, furnished with an iron cover, and placed in furnaces. The pyroacetic, formerly called the pyroligneous, acid, which is formed in the destructive distillation of wood, is caught for use. This acid is useful to the calico printer, dyer, &c. in making their iron liquor, and when purified, is employed in Europe in the place of vinegar, as it is more pungent, and highly concentrated.

When pine and various kinds of wood, which yield turpentine, are carbonized, we obtain tar during the process.

Chaptal informs us, that tar is obtained from the wood of the trunk, branches, and roots of the pine, which are heaped together, covered with turf, and set on fire to produce a close combustion, in the same manner as for making charcoal. The oily parts which are disengaged, trickle down, and are received in a gutter, which serves to convey them to a tub. The most fluid part is sold under the name of huile de cade; and the thicker part is the tar used for paying or painting the parts of shipping and other vessels.

According to the wood submitted to the process of charring, the products are, more or less, various; but in all cases it is only the solid part, or ligneous fibre, that furnishes the coal. By the ordinary process we obtain sundry volatile products, among which are pyroacetic acid and carburetted hydrogen gas.

When wood is carbonized in the usual manner, it yields from 16 to 17 parts of charcoal in the hundred; but when the operation is conducted in close vessels, the product is 28 per cent. a saving of eleven or twelve per cent. By this difference in the quantity, it appears that eleven or twelve per cent. is burnt in the common process.

M. Mollerat was the first who tried the experiment with iron cylinders.

M. Vauquelin (Annales de Chimie, tome lxvi, p. 174) has given some observations on the carbonization of wood in close vessels, predicated on a Memoir of M. Mollerat; both of which are interesting. The apparatus used by M. Mollerat is described by Thenard, (Traité de Chimie, iii, p. 373,) to be composed of two parts, viz: a furnace with a moveable dome, and a cylindrical kettle, or vessel of iron sufficiently large to contain a cord of wood. It is furnished with a cover and pipe. The pyroacetic acid is collected. Smaller cylinders are preferred, because the wood is ignited more readily and the charcoal is more of a uniform quality.

From 100 parts of the following named woods, Messrs. Allen and Pepys (Phil. Trans. 1807) obtained the following proportional parts of charcoal:

See also the experiments of Mr. Mushet, in the third volume of Tilloch's Magazine.

It appears by the Annales de Chimie, vol. 66, and the Retrospect of Discoveries, vol. vi, p. 100, that three brothers have established at Pellerey, near Nuits, Cote d'Or, a manufactory on a large scale, for making charcoal in close vessels.

The quantity of charcoal they obtained is double that by the usual mode, while it requires only one-eighth part of wood to be consumed in the distillation; it is also better than the common, as a given quantity evaporates one-tenth more water than the other; hence iron masters may obtain twice as much iron from the use of a given quantity of wood; and in addition to this, there is also prepared a number of other articles, of each of which in order.

350 kilogrammes (700 lbs.) of wood, yield 25 or 30 of tar, which retains so much acid that it is soluble in water; but when it is washed, and rendered thick by boiling, for some time, it offers more resistance to water. If mixed with one-fifth of rosin it is rendered equally fit for the use of ships, &c. as the common tar.

Four sorts of vinegar are prepared, all of which are perfectly limpid, which do not, like the common, contain any tartar, malic acid, resinous or extractive matter, nor indeed any mineral acid, lime, copper, or other substances. The simple vinegar marks—2° hydrometer for salts, at 12° centigrade thermo. it is stronger tasted than common vinegar, and produces a disagreeable irritation. The aromatic vinegar is prepared with tarragon, the smell is agreeable, but it has the same fault as the former. The vinous vinegar is formed by adding some alcohol to simple vinegar; it has a very sensible odour of acetic ether; the alcohol softens the flavour in some degree, but the vinegar is still very sharp. The acid, called strong vinegar, is in fact a very good acetic acid at 10¹/₂° hydr., it is very white, clear, and sharp, without the usual burnt flavour, and seems to form the basis of the preceding kinds. It can be sold for 8 or 9 francs (7s.) per lb. which is only half the price of that distilled from verdigris. Although not so agreeable to the taste as common vinegar, these new kinds are more elegant to the eye, and do not mother.

The editor of the Retrospect makes the following observations:

The proprietors of this manufactory seem to be perfectly aware of all the several productions which could be prepared from the refuse of their principal object; and we have no doubt but that the substances they procure in this manner will amply compensate them for the use of the capital that must be invested in building the furnaces.

The nature of the vessels in which they distil the wood is not mentioned, but they are probably cast iron retorts, or vessels of a similar nature, in which a distillation per latus takes place. The application, therefore, of lord Dundonald's furnaces for procuring coke to this purpose would be still more advantageous.

A cubic yard of wood yields 100 quarts of acid liquor, besides 50 or 60 lbs. of thick oil.

The method of making charcoal of a uniform quality, for which a Mr. Kurtz has taken out a patent, is the following:

A sheet-iron chest, which has a cover that fits it tight, and a pipe, or tube, that descends nearly to the bottom, and coming out from its side above, is fixed in brick work. In this the billets of wood are put. Fire is then made underneath. It is obvious, that the wood is kept at one temperature from its being immersed in vapour, as the vapour cannot escape at the top, but must descend to the bottom, and then proceed up the pipe, by which it is conveyed away. The effect is, that the charring process goes on regularly, and the wood is charred equally. The carbonization is finished when the vapour ceases to appear, and nothing but carburetted hydrogen gas escapes. The charring of bones is performed in iron cylinders, furnished with tubes to receive, and convey away, the impure ammonia.

In the manufacture of powder, particular kinds of wood are selected for carbonization. These are generally, willow, hazle, maple, poplar, linden, buckthorn, or alder, or those which are tender and light, because, as they are less dense, and consequently more friable, they enflame and consume more rapidly: they are known in the arts by the name of white wood. When a less sudden effect is to be produced with the gunpowder, and the combustion prolonged, as in some sky-rockets, the charcoal of hard wood is to be preferred, such as the oak, beech, &c. When the wood is gathered, the bark is removed, and the wood exposed to the sun to dry: it is then cut into billets, and charred. The ashes, if any be formed, are to be carefully separated.

In considering the use of charcoal, therefore, for the preparation of gunpowder, we are to direct our inquiries to the choice of wood for carbonization, and the best process for carbonizing it. All light woods, we remarked, as the linden, willow, poplar, &c. furnish the lightest coal, and on that account are preferred. It is remarked, that tender wood, besides making a light, friable, and porous coal, is more combustible than ordinary hard, and more compact wood, and the coal that it furnishes leaves less residue after combustion.

Many experiments have been made with coal prepared from different kinds of wood, with a view of ascertaining the kind best adapted for the manufacture of gunpowder. M. Letort, at the powder mills of Essonne, in France, instituted a number of experiments of this kind. He made gunpowder with the coal of several kinds of wood, and compared its effects by a mortar eprouvette. The result was, that the powder made with the coal of poplar, was the strongest; and the other powder, made with the coal of the linden, willow, &c. was of the same quality throughout. As to the second inquiry, it is hardly necessary to repeat, that for the complete and thorough carbonization of the wood, to produce at the same time coal of a uniform quality, the process of charring in iron cylinders or close vessels, is to be preferred. The point to be attended to is, to bring the wood to a complete state of ignition, and consequently to disengage all the volatile or fluid parts. When the gas (carburetted hydrogen) ceases to appear, it is a criterion that the operation is finished. This gas, it is to be recollected, will come over even after the whole of the wood is completely ignited. The first volatile product is the pyroacetic acid. Some saturate the acid liquor with chalk, and decompose the acetate of lime with sulphate of soda, and separate the acetic acid from the acetate of soda by distillation with sulphuric acid. The acetic acid is then tolerably pure, and may be diluted for use.

It is observed, however, that when charcoal, prepared in iron cylinders, is designed for gunpowder, the last portion of vinegar and tar must be allowed to escape, and the reabsorption of the crude vapours prevented, by cutting off the communication between the interior of the cylinders and the apparatus for condensing the pyroacetic acid, whenever the fire is withdrawn from the furnace. If this precaution be not taken, the gunpowder made with the charcoal would be of inferior quality.

On a large scale, when the object is also to prepare the vinegar of wood, a series of cast-iron cylinders, about four feet diameter, and six feet long, are built horizontally, in brick-work, so that the flame of one furnace may play round about two cylinders. Both ends project a little from the brick-work. One of them has a disc of cast iron well fitted and firmly bolted to it, from the centre of which disc an iron tube about six inches diameter proceeds, and enters at a right angle, the main tube of the refrigeration. The diameter of this tube may be from 9 to 14 inches, according to the number of cylinders. The other end of the cylinder is called the mouth of the retort. This is closed by a disc of iron, smeared round the edge, with clay lute, and secured in its place by wedges. The charge of wood for such a cylinder is about 8 cwt. The hard woods, oak, ash, birch, and beech, are alone used. Fir does not answer. The heat is kept up during the day-time, and the furnace is allowed to cool during the night. Next morning the door is opened, the coal removed, and a new charge of wood is introduced. The average product of crude vinegar is 35 gallons. Its total weight is about 300 lbs. But the residuary charcoal, according to Ure, (Chemical Dictionary), from whom we have taken this account, is found to weigh no more than one-fifth of the wood employed. The crude pyroacetic acid is rectified by a second distillation, in a copper still, in the body of which about 20 gallons of viscid tarry matter are left for every 100. Its acid powers are now superior to the best household vinegar in the proportion of 3 to 2. Ure observes, that by distillation, saturation with quicklime, evaporation of the liquid acetate to dryness, and gentle torrefaction, the empyreumatic matter is so completely dissipated, that on decomposing the calcareous salt by sulphuric acid, a pure, perfectly colourless, and grateful vinegar rises in distillation. Pyroacetic acid is said to be a powerful antiseptic. M. Monge, Dr. Jorg, and more lately, Mr. Ramsay, of Glasgow, have made experiments with it. Fish dipped in it have been preserved for many days, and meat treated in the same manner, has also been preserved from putrefaction.

With respect to the pulverization of charcoal, the operation is so exceedingly simple, that we deem it unnecessary to notice it. It is obvious, that mortars, mills, &c. may be used, with fine or coarse sieves. For fire-works, charcoal is frequently pulverized in a leather sack, in the same manner as grained powder is reduced to meal-powder. It may be made either coarse or fine, to answer different purposes, by employing sieves of different kinds. Charcoal may be separated from nitre and sulphur, in gunpowder, by a simple process, which may be seen by referring to the section on gunpowder.

The quantity of carbon in coal, is directly proportionate to the quantity required for the decomposition of nitrate of potassa, a fact necessary to be considered in the theory of the action of charcoal in gunpowder. Thus, Mr. Kirwan found that, 12.709 of carbon are necessary to decompose 100 of nitrate of potassa. It will be easy to deduce the quantity of carbon, in a given weight of coal, from the quantity of nitrate of potassa it is capable of decomposing. The experiment is made very readily by fusing in a crucible, five hundred or more grains of nitre, and when red-hot projecting by degrees the powdered coal on the nitre. When the detonation produced by one projection of coal has ceased, add a new portion till it produces no farther effect.

Charcoal may be made intensely black, resembling ivory black, according to M. Denys-de-Montfort, (Bibliothèque Physico-Economique, for March 1815,) by pulverizing it very fine, mixing it with wine lees, and drying the mixture, and then subjecting it to a strong heat in a covered crucible, or other vessel.

Sec. VII. Of Gunpowder.

M. Langles, who read a memoir on this subject to the National Institute, in 1798, observes, that the Arabians obtained a knowledge of gunpowder from the Indians, who had been acquainted with it from the earliest periods. The use of it was forbidden in their sacred books, the veidam or vede. It was employed in 690 at the battle near Mecca. As nitre was employed in all probability in the Greek fire, invented about the year 678, it is supposed, that that composition gave rise to the invention of gunpowder.

Various prescriptions, or formulæ, have been given for the preparation of this fire. The oldest is by princess Anna Commena, in which, however, there is only resin, sulphur, and oil. Beckman observes, that the first certain mention of saltpetre will be found in the oldest account of the preparation of gunpowder, which, in his opinion, became known in the thirteenth century, about the same time that the use of the Greek fire, of which there were many kinds, began to be lost. The oldest information on this subject is to be found in the works of Albertus Magnus, and the writings of Roger Bacon. The true recipe for making the Greek fire, and the oldest for gunpowder, were found in a manuscript, preserved in the electoral library at Munich. Various copies of this manuscript were made. Bacon employed this writing, which was mentioned by Jebb, in the preface to his edition, from a copy preserved in the library of Dr. Mead. Whether the writer was Marcus Græcus, is of no moment; for Cardan observes, that the fire that can be kindled by water, or rather not extinguished by water, was prepared by Marcus Gracchus.

The former Marcus, mentions two kinds of fire-works; and the composition, which he prescribes for both, is two pounds of charcoal, one pound of sulphur, and six pounds of saltpetre, well powdered and mixed together in a stone mortar.

Friar Bacon, who lived three centuries after Græcus, was in possession of the recipe. It was concealed, however, from the people, veiled in mystery. In his treatise De Secretis Operibus Artis et Naturæ, &c. the secret of the composition is thus expressed: "sed tamen salispetræ, LURU MOPE CAN URBE et sulphuris; et sic facies tonitrum et corruscationem, si scias artificium." Luru mope can urbe, is the anagram for carbonum pulvere. Bacon supposes, that it was with a similar composition that Gideon defeated the Midianites, with only three hundred men. Besides the use of gunpowder in the 9th century, in the war between the Tunisians and the Moors, in which the former are said to have employed "certain tubes or barrels, wherewith they threw thunderbolts of fire," the Venetians employed it against the Genoese, and it was reprobated as a manifest contravention of fair warfare.

Peter Mexia, in his "Various Readings," relates, that the Moors, being besieged, in 1349, by Alphonso the eleventh, king of Castille, discharged a kind of iron mortars upon them, which made a noise like thunder. This, with the sea-combat between the Tunisians and the Moors, stated on the authority of don Pedro, bishop of Leon, places the invention much earlier than by some writers.

Polydore Virgil ascribes the invention of gunpowder to a chemist, who, having put some of his composition in a mortar, and covered it with a stone, was blown up, in consequence of its accidentally taking fire. The person here alluded to, according to Thevet, was a monk of Friburg, named Constantine Anelzen. Others, as Belleforet, with more probability, hold it to be Bartholodus Schwartz, or the black, who discovered it, as some say, about the year 1320. Du Cange, however, remarks, that there is no mention made of gunpowder in the registers of the chamber of accounts in France, as early as the year 1338. Roger Bacon knew of gunpowder, near one hundred years before Schwartz was born. (See the invention of cannon, in military fire-works, fourth part.)

It is certain, that Albert de Bollstædt indicated the constituent parts of gunpowder, when he says, in his Mirabilis Mundi, "Ignis volans, accipe libram unam, sulphuris, libras duas, carbonas salicis, libras sex, salis petrosi, quæ tria subtilissime terantur in lapide marmorea; postea aliquid posterius ad libitum in tunica de papyro volante, vel tonitrum faciente ponatur.

"Tunica ad volandum debet esse longa, gracilis, pulvere illo optime plena, ad faciendum vero tonitrum brevis, grossa et semiplena."

Gunpowder was of a much weaker composition than that now in use, or that described by Marcus Græcus. Tartalgia, (Ques. and Inv. lib. 3, ques. 5), observes, that, of twenty-three different compositions, used at different times, the first, which was the oldest, contained equal parts of the three ingredients. When guns of modern construction came into use, gunpowder of the present strength was introduced.

The strength of powder depends upon the proportions of the ingredients, they being pure; and Mr. Napier observes, (Trans. Royal Irish Academy, ii.) that the greatest strength is produced, when the proportions are, nitre, three pounds, charcoal, nine ounces, and sulphur, three ounces. The cannon powder was in meal, and the musket powder in grain.

In the time of Tartalgia, the cannon powder was made of four parts of nitre, one of sulphur, and one of charcoal; and the musket powder of forty-eight parts of nitre, seven parts of sulphur, and eight parts of charcoal; or of eighteen parts of nitre, two parts of sulphur, and three parts of charcoal.

The intimate mixture, therefore, and the determinate proportions of saltpetre, charcoal, and sulphur, form gunpowder; the different qualities of which, depend, as well upon the proportions which are used, as on the purity of the materials, and the accuracy with which they are mixed.

Gunpowder is reckoned to explode at about 600° Fahr; but, if heated to a degree just below that of faint redness, the sulphur will mostly burn off, leaving the nitre and charcoal unaltered.

The saltpetre should be perfectly refined, and entirely free from deliquescent salts; the sulphur as pure as possible, and, for that reason, a preference should be given, to that which is sublimed, or distilled; and the charcoal should be prepared in iron cylinders, as described under that head, from woods, which are light and tender, as the linden, willow, hazle, dogwood, etc.

There is a considerable difference in the proportions used by different nations; but, from the many accurate and conclusive experiments of the French chemists, their formula is certainly the most perfect. In English powder, three-quarters of the composition are nitre, and the other quarter is made up of equal parts of charcoal and sulphur; but sometimes, to seventy-five parts of nitre, fifteen of charcoal is used, adding ten of sulphur. Their government powder is the same for cannon, as for small-arms.

According to a number of experiments, made at Grenille, it was found, that the proportion of saltpetre in gunpowder, must be in a given ratio with the charcoal, so that the latter might effectually decompose it in the act of combustion; and hence the ratio is as 12 of the latter to 75 of the former, and these, with 12 of sulphur, are the proportions generally employed. Ruggeri (Pyrotechnie Militaire, p. 91,) gives, as the proportions, 12 parts of saltpetre of the third boiling, 2 parts of charcoal, and 1 part of sulphur. The proportions, used in Sweden, are 75 saltpetre, 9 sulphur, and 16 charcoal; in Poland, 80 saltpetre, 8 sulphur, and 12 charcoal; in Italy, 76 saltpetre, 12 sulphur, and 12 charcoal; in Russia, 70 saltpetre, 11 sulphur, and 18¹/₂ charcoal; in Denmark, 80 saltpetre, 10 sulphur, and 10 charcoal; in Holland, 76 saltpetre, 12 sulphur, and 12 charcoal; in Prussia and Austria, 78 saltpetre, 11 sulphur, and 11 charcoal; and in Spain, 77 saltpetre, 11¹/₂ sulphur, and 11¹/₂ charcoal.

According to Klaproth and Wolff, (Dictionnaire de Chimie, translated into French by MM. Lagrange and Vogel), Berlin powder is composed of three-quarters nitre; one-eighth sulphur, and one-eighth charcoal; Chinese powder, of 16 parts nitre, 6 charcoal, and 4 sulphur; Swedish powder, of 75 parts nitre, 16 sulphur, and 9 charcoal; the powder of Lissa, of 80 nitre, 12 sulphur, and 8 charcoal; and English powder, on the authority of Beckman, as follows: Powder for war, 100 parts of nitre, 25 charcoal, and 25 sulphur; musket powder, 100 nitre, 18 sulphur, and 20 charcoal; pistol powder, 100 nitre, 23 sulphur, and 15 charcoal; strong cannon powder, 100 nitre, 20 sulphur, and 24 charcoal; strong musket powder, 100 nitre, 15 sulphur, and 18 charcoal; and strong pistol powder, 100 nitre, 10 sulphur, and 18 charcoal. German powder, for war, is composed, generally, of 0.70 saltpetre, 0.16 charcoal, and 0.14 sulphur. A small portion of gum is sometimes added, to make the grain firmer; but such additions retard the combustion, and the effect.

The addition of gum arabic, however small, must injure the quality of gunpowder, although it has the effect of making the grain firmer, and less liable to fall into meal powder. The grain is also made heavier, and less liable to absorb moisture. M. Proust, in his second memoir on gunpowder, mentions the use of icthyocolla, a fish glue, for the same purpose; and, nevertheless, speaks of some advantages that the gunpowder, prepared with it, possesses.

It is observed by Mr. Coleman, of the Royal Powder Mills of Waltham abbey, that it is not exactly ascertained, whether there is any one proportion, which ought always to be adhered to, and for every purpose. We have no hesitation in believing, for our own part, that the French formula is the most correct, from the numerous experiments made at the royal manufactory at Essone, near Paris.

A very considerable variation is found in the proportions of the ingredients of the powder of different nations and different manufactories. The powder made in England, is the same for cannon as for small arms, the difference being only in the size of the grains; but in France, it appears, that there were formerly six different sorts manufactured; namely, the strong and the weak cannon powder, the strong and the weak musquet powder, and the strong and the weak pistol powder. The following are the proportions in each, though the reason of this nicety of distinction is not very obvious. For the strong cannon powder, the nitre, sulphur, and charcoal were in the proportions of 100 of the first, 25 of the second, and 25 of the third: for the weak cannon powder, 100, 20, and 24: for the strong musket powder, 100, 18, and 20; for the weak, 100, 15, and 18: for the strong pistol powder, 100, 12, and 15; for the weak, 100, 10, and 18.

The Chinese powder appears, by the analysis of Mr. Napier, to be nearly in the proportions of 100 of nitre, 18 of charcoal, and 11 of sulphur. This powder, which was procured from Canton, was large-grained, not very strong, but hard, well coloured, and in very good preservation.

The following proportions are now used in France, for the manufacture of gunpowder for war, for hunting, and for mining.

After having made choice of the materials, the nitre being pulverized, is passed through a brass sieve; the sulphur is pulverized by means of a muller, or other contrivance, and also sifted in a bolter; the quantities are then weighed, as well as the charcoal.

The mixing of these substances is performed in a series of mortars, hollowed out of a strong piece of oak wood; and by the aid of pestles or stampers, which are set in motion by machinery and water power, the mixture is thoroughly made. The end of the stampers is usually covered with, and sometimes made of, brass, and the mortars are also, in some powder mills, lined with brass. The mill has generally two rows of mortars and stampers, of ten each. The nitre, sulphur, and charcoal, in proper proportions, are put into each mortar. The charcoal is first introduced into the mortar, being sometimes previously pulverized; then wetted with water, and the pounding is continued for thirty minutes. The nitre and the sulphur are then added, and the whole is stirred with the hand. More water is then added; it is again stirred, and the operation of pounding is continued. The object of adding the water is to prevent the so called volatilization of the ingredients, and to give the mixture the consistency of paste, and at the same time to prevent the explosion of the powder; a circumstance, which must be always guarded against.

After the operation is continued for half an hour, the pounders are stopt, and the powder is then re-exchanged by means of copper or brass ladles; that is to say, the powder of the first mortar is removed, and put into a box, and the contents of the second mortar are put into the first, that of the third is put into the second, that of the fourth into the third, &c. in succession, and in the last, the contents of the first mortar.

We make, in this manner, twelve exchanges, allowing one hour between two, and adding water from time to time, to the mixture, and especially during the summer months. After this, the pounders are again set in motion, for the space of two hours, and the operation is finished. Fourteen hours are generally required to complete the mixture, which is then in the form of paste. It is then granulated. After being partially dried, the graining is performed by passing it through sieves, which are more generally formed of parchment. These sieves are made to work horizontally, and the powder is caught in vessels placed beneath. The size of the grain depends on the sieve; hence, fine grain, or coarse grain powder is thus obtained. In the sieve is usually placed a contrivance to break the masses, and to cause the powder to pass through in grains. After this, the powder is again passed through a second sieve, commonly called a grainer, the holes of which are of the same diameter as the powder we wish to obtain. It is then put into another sieve, which permits only the dust to pass, whilst the grain-powder remains. As the powder, however, contains some grains too large, as well as others too small, we may separate the former by a fourth sieve, of a suitable size. The dust and fine grain are carried to the mill, and worked over. The powder for war, and for mining, is dried immediately after the graining.

Formerly, the powder was dried in the open air, by spreading it on tables lined with cloth, or in oblong boxes; but serious inconveniences resulted from it, and, particularly, the powdermakers were obliged to watch the temperature, as well as the state of the atmosphere. When the latter was moist, the drying was suspended.

M. Champy, however, has obviated these inconveniences by a very advantageous process, which consists in raising the temperature of the air to 50 or 60 degrees, and causing it to pass from the chamber in which it is heated, through cloths, on which is spread a bed of powder, of a certain thickness. By this means, large quantities of powder may be dried, in all seasons of the year, in a short time, and at little expense. In whatever manner the drying is performed, there is always more or less dust formed, which, to make the grain of one uniform appearance, must be separated by a hair sieve. This operation is called the dusting.

Whether we adopt the plan recommended by M. Champy, or heat the rooms for the drying of powder to a certain temperature, by means of steam pipes, a plan which presents every advantage, or use the old mode, the effect is the same.

The musket, or hunting powder, undergoes an operation more than the powder for war, namely, that of glazing, which is performed before it is dried. With the exception of this process, it is made in the same manner, using, however, a finer sieve in granulating it. The glazing has for its object the smoothing, or removing the asperities of the grain, and to prevent its falling into dust, and soiling the hands.

The powder intended for glazing is first exposed an hour to the sun on one cloth, in winter, and between two cloths in summer, in order to dry it more perfectly, which is very necessary before the operation of glazing. For this purpose, it is put into a vessel like a barrel, which is turned horizontally upon its axis, by machinery. This barrel is furnished with bars that go across, intended to augment the friction, or rubbing of the grain, and expedite the process. The barrels are made to turn slowly, to avoid breaking the grain, and at the expiration of eight or twelve hours, the glazing is finished, the powder having acquired a sufficient hardness and polish. After removing the powder, the dust is separated in the usual manner.

Gunpowder-mills are mills, in which powder is prepared, by pounding and beating together the ingredients of which it is composed. They are always worked by water-power, and as there are generally many of them belonging to the same manufactory, one dam of water will furnish a sufficient supply. In the construction of powder-mills, the frame of the house is made very stout, and the roof put on lightly, so that in case of explosion, it may be carried off easily, and thus give vent to the powder, without much injury to the works. The lights, to enable the work to be carried on at night, are placed on the outside of the building, beyond the reach of the powder, and by means of glass windows, the light passes into the mill. It is lamentable, indeed, that so many accidents occur in the operation of making powder. This may take place, as it has to our knowledge, by the friction of the pounders. Their weight, the rapid succession of the blows, and the dryness of the powder, are the principal causes of such accidents, and sometimes by the inattention of the workmen, suffering nails, and the like, to get among the materials. I once witnessed the effect of an explosion of the kind, in the neighbourhood of Frankford, in the vicinity of Philadelphia, at the old and well-known powder mills, at that place. It was produced, in consequence of the friction, by the neglect of the men not adding water at a proper time, to keep the materials moist. The mill in which the explosion took place was not much injured; but the roof, together with the men, were sent a considerable distance. Some of the latter fell into the mill-race, and were much injured. The effect, however, did not stop here; for the fire communicated, strange as it may appear, to some of the other mills, although at some distance, and blew them up. Several explosions have happened at the same mills.