GUNPOWDER

From Agepedia

GUNPOWDER is a mixture of saltpetre, sulphur and charcoal. If we may believe the relations of the missionaries, and the reports of the Chinese historians, the Chinese were first acquainted with the application of gunpowder. Perhaps it proceeded from them to the Arabs; for, in 1331, the Moors used it in their operations before Alicant, and certainly in 1342, at Algesiras; in 1250, the Arabs probably used a mixture similar to gunpowder be fore Damietta, and perhaps also in a naval engagement in the year 1085. Among the Europeans, the traces of this invention are still more ancient; for the Greek fire, which was first employed in 668, must have, at least, contained saltpetre mixed with pitch, naphtha, &c, since it was customary, by means of it, to hurl stones from metallic tubes. The first information of the knowledge of the Europeans with regard to the chemical mixture of powder, is found in the 9th centuIT, in a book composed by Marcus Gracchus, preserved in the university of Oxford, which also accurately explains its composition. Roger Bacon (who died hi 1294) was likewise acquainted with the power which saltpetre has, when set on fire, of producing a thundering report. The discoverer of the power of powder, when confined and set on fire, of propelling heavy bodies, was, according to common report, Berthold Schwartz, a monk, who is said to have lived at Mayence, between 1290 and 1320. He, in some of his experiments in alchemy, had put the mixture into a mortar, and, having accidentally dropped into it a spark of fire, to his astonishment, saw the pestle fly off into the air. Other traditions attribute this invention to Constantine Antlitz of Cologne (see De Boucher's MSmoire sur V Origine de la Poudre a Canon), However this may be, powder was scarcely applied to military uses before 1350, and the accounts of the use of cannons in the battles of Crecy (1346), Poictiers, and still earlier engagements, have arisen from the various significations of the word cannon. In 1356, powder is mentioned in the accounts of the treasury of Nuremburg ; in 1360, the house of assembly at Liibeck was burned by the imprudence of the powder manufacturers ; xand, in 1365, the margrave of Misnia had pieces of artillery. In the course of a few years afterwards, it was known over all Europe. Thus the first traces of this invention would appear to be found in Germany ; other nations, however, have put in their claims to this honor. The proportion of the ingredients in the composition of GUNPOWDER, is different in different countries : in the Prussian powdermills, 75 parts of saltpetre, 11^ parts of sulphur, and 13^ parts of charcoal are used ; but in the French mills, 75 parts of saltpetre, 12£ of coal, and 12h of sulphur. In the manufacture of this article, which is earned on in very different ways, much depends upon the goodness of the ingredients. The crude saltpetre is broken up, moistened and exposed to tlv action of a slow fire, contin ually skimmed and violently agitated, till all the moisture evaporates, and the saltpetre remains in the form of a fine powder. The sulphur is pulverized after having been well purified. The charcoal is that derived from the alder or any other soft wood or bushes, as, for example, hemp stalks, which are burned with great care in a confined room, and reduced to a fine powder. These three ingredients are then moistened, brought under a stamping, or more commonly a rolling mill, where two metallic, or, which are better, marble cylinders, turn round a fixed vertical wooden pillar, and crush to pieces the mixture, which lies upon a round smooth surface of the same material. Other mills effect tliis bruising operation by several large iron runners, revolving upon a metallic plate, similar to a painter's grinding stone, or by a rapid revolution of the mixture in casks containing metallic balls. After the mixture, in some one of these ways, has been acted on in the mills for the space of six or eight hours, and when the ingredients are united, and form one homogeneous mass, it is pressed, while yet wet, by means of cylindric rollers of wood, through a sieve of perforated parchment, by which the powder is formed into grains. In other mills, this process of forming it into grains takes place after the powder has been pressed between two boards into a solid cake, and then submitted twice to the operation of a grooved roller. The powder, after it has been grained, is spread upon boards in the dryinghouses, and exposed to the strong heat of an oven for two days. In order to prevent its taking fire, the oven is well lined with clay and copper. Of late years, this process of drying has been sometimes effected by means of steam. Finally, the powder is sorted by being passed through several sieves. In the first, or coarsest, remains what is entirely useless ; through the second passes the secondsized, or cannon powder ; and through the third and last the finest, or musket powder. The powder, thus prepared, is packed in oaken casks. In order to provide against accidents, the English use copper casks or vessels, with the tops screwed on. Copper vessels are also used in the U. States. Good gunpowder must be of a slate color, uniform, round and pure grain, and also have a uniform color on being broken up ; nor should it leave behind it, either on the hand or on paper, any black spots. When set on fire, it should burn at once, without crackling or leaving upon paper any ap pearances of its combustion. When applied to the tongue, the taste should be extremely cooling. In order to prove its strength, let any person apply an accurately fitting ball to a small mortar, and the distance to which the ball is thrown will prove the strength of the powder. The French government eprouvette is a mortar seven French inches in diameter, and three ounces of powder must throw a copper globe, of 60 pounds weight, f300 feet; otherwise the powder is not admissible. An eprouvette is sometimes used which is inaccurate ; the powder throws back the cover of a small mortar, and with it a wheel, which catches in a steel spring ; the strength is determined by the tooth, at which the wheel remains fixed. This method is defective, because the spring is weakened by use. Another method is, to suspend a small cannon as a pendulum, and to judge of the strength of the powder by the force of the recoil, which will describe a greater or less arc of a circle. In the preservation of powder, fire and water must both be carefully guarded against. Powder destined for military purposes, should be deposited in an airy building, removed at least 1000 paces from any habitation, provided with lightning rods, and surrounded with walls, ditches and palisadoes ; there should be a guard constantly set, to prevent the introduction of fire, and to hinder all persons from entering, who have things about them that will produce fire. These buildings should contain openings for the free passage of the air; the casks should stand upon a platform of wood, at a distance from the wall, and the powder itself should be sunned and dried every one or two years. If the powder is to be kept in damp places, as, for example, in the casemates (arched passages under ground) of fortresses, the walls should be internally covered with lead, and a vessel filled with unslacked lime placed in the middle of the apartment, so that the moisture of the atmosphere may be attracted by the lime. In the transportation of gunpowder, dust, which is liable to penetrate the cracks and joints of the casks, should be carefully guarded against, as the friction may produce explosion. It is also necessary for its good preservation, that the carnages and vessels in which it is transported should be watertight. We may effectually preserve it from moisture, by dipping the cask and the sackcloth covering into melted pitch. Vessels prepared in this way, and containing powder, may be immersed in the water for weeks, without having their contents in the least injured. The effects of this substance, when set on fire, are truly wonderful. When powder is heaped up in the open air, and then inflamed, it detonates without report or effect. A small quantity of powder left free in a room, and fired, merely blows out the windows ; but the same quantity, when confined in a bomb within the same chamber, and inflamed, tears in pieces and sets on fire the whole house. Count Rumford loaded a mortar with onetwentieth of an ounce of powder, and placed upon it a 24 pound cannon, weighing 8081 pounds; he then closed up every opening as completely as possible,and fired the charge, which burst the mortar with a tremendous explosion, and raised up this immense weight. Whence such and similar effects arise, no chemist as yet has been able, satisfactorily, to explain; and the greater part of the explanations hitherto made are nothing but descriptions of facts. The best explanation is, that the azote and oxygen gases of the saltpetre, and the carbonic acid gas from the charcoal, which had hitherto been in a solid state, are set free, and the expansive power of all these gases requires much more room than they previously occupied. They now endeavor to overcome the obstructions to their expansion, and this tendency is very much increased by the intense heat generated by the gases. The confined steam operates in the same way, although this is not the only cause of the phenomenon, as Rumford supposes.