Pyrotechny (Gr. , fire, and , art), the art of making fireworks for public exhibitions or for military purposes. Until the invention of gunpowder, and before the properties of saltpetre were understood, fireworks may be said to have been unknown in Europe; but the Chinese from an early period were skilful in true pyrotechnic works. In Europe the art was first cultivated by the Italians; and it was described by Biringucci Vanuccio in his work De la pirotechnia (1540). In France the subject was treated by J. Hanzelet in his Traités militaires (1598), who recommended the use of the rocket in war, thus anticipating Con-greve. The Chinese had from an unknown period employed the rocket as an offensive weapon, affixing to it a pointed barb like that of an arrow. Among the earliest pyrotechnic displays of much note in Europe were the exhibitions at Fontainebleau by Sully in 1606, and by Morel, commissary of artillery, in 1612. The rejoicings at the establishment of peace in 1739 gave occasion for splendid exhibitions at the hôtel de ville and the Pont Neuf in Paris and at Versailles. - The compositions prepared for fireworks are too numerous to be even named in this article, and reference can be made merely to the materials commonly employed, with exemplifications of the manner in which they are compounded in a few of the principal pieces.
Gunpowder and its ingredients, nitre, sulphur, and charcoal, are the chief constituents of fireworks. Iron and steel filings and cast-iron borings, which must be free from rust, are used to increase the vividness of the combustion, and produce what is known as the Chinese "brilliant fire." It is these which are thrown out by rockets as they explode, and produce the bright sparks as they meet the oxygen of the air. Copper filings and the salts of copper give a greenish tint to the fire; zinc filings, a fine blue; sulphuret of antimony, a light greenish blue with much smoke; amber, rosin, and common salt protected against dampness, are used to give a yellow fire; a red is produced by lampblack, and a pink by nitre in excess; the salts of strontia also give a red color, and those of barytes a green. - The most useful piece of fireworks is the sky rocket, employed as a signal, and under favorable circumstances visible for 30 leagues. As a warlike missile it will be treated under Rocket. In exhibitions of fireworks the rocket is aluminous projectile, made to dart upward with immense velocity and a loud hissing sound, and explode at the top of its flight.
It is sent up singly or in volleys of great numbers together, and as they explode each one commonly discharges colored lights which descend in brilliant showers, or dart forth in every direction with the irregular motions of the so-called fusees and serpents. It is made of various compositions, which are packed in tubes formed by rolling paper hard round a cylindrical core. The match by which the rocket is to be fired is introduced into the cavity at the bottom, and the whole exposed surface of the composition forming the walls of the cavity is instantly ignited. The gaseous products, being violently ejected from the open end, react with equal force, carrying the rocket forward in the other direction. The movement would be extremely wild if not controlled by some regulator. This is furnished in a long balance stick firmly tied to the rocket and projecting several feet behind. It is made of light wood, and when it is set free after the explosion it rarely falls with sufficient velocity to do any harm. Long triangular pieces of pasteboard have been secured by the edge to the sides of the rocket as a substitute for the stick, and have also served to steady its movement.
Among the decorations or garnitures for the rockets are stars, small cylindrical or cubical bodies variously compounded, as of 1 part of sulphuret of antimony, 2 of quartz, 2 of gunpowder, 15 of nitre, 6 of sulphur, and 2 of zinc filings. The materials, being separately pulverized, are mixed into a stiff paste with gum water or glue, made into the desired shapes, rolled in gunpowder, and dried. - Roman candles are cylindrical cases charged with stars alternating with a composition like that of the rockets, and with gunpowder. A small quantity of the composition is rammed into the bottom of the case, upon this a little gunpowder, and a star is then pushed down upon the powder. These charges are repeated in the same order until the case is filled. The end is then closed with a piece of match paper pasted round the outside and drawn to a point at the top. When this is fired the charges are shot at short intervals successively from the tube into the air. The effect is heightened by varying the composition and colors of the stars. A red fire adapted for this or other pieces may be made by mixing 4 parts of dry nitrate of strontia with 15 of pulverized gunpowder; or this may be varied with 40 parts of the strontia, 13 of sulphur, 5 of chlorate of potash, and 4 of sulphuret of antimony.
The usual precautions should be observed in pulverizing and mixing the chlorate of potash. A green fire like that burned in theatres, which give3 to everything upon the stage a death-like aspect, is produced by 77 parts of nitrate of barytes, 13 of sulphur, 5 of chlorate of potash, 3 of pulverized charcoal, and 2 of arsenic. - Bengal lights, also called blue lights, and used by ships as night signals, are compounded of nitre 7 or 5 parts, sulphur 2, antimony 1; or for the sparkling ones, 4 each of sulphur and nitre, 1 of antimony, and 2 of fulminating composition (of fulminating mercury and gunpowder). The proportions of these ingredients may be variously modified from those given. - The published works on pyrotechny are mostly of the 17th and 18th centuries. Those of more recent date are: L'art He faire à peu de frais les feux d'artifice (Paris, 1828); Manuel de l'artificier, by A. D. Vergnaud (Paris, 1828); and "Pyrotechny," by G. W. Mortimer (London, 1853). The fullest work in English is "System of Pyrotechny, comprehending the Theory and Practice, with the Application of Chemistry," by James Cut-bush (large 8vo, Philadelphia, 1825).