Preparations of gunpowder, sulphur, metallic filings, and salts, to be set on fire. The most common form of firework is a pasteboard tube filled with these explosive materials. A number of these tubes are often arranged so as to make, when kindled, a great variety of figures in fire variously colored. Stars are made of nitrate of strontia and gunpowder. Rockets are used in war and as ship signals, as well as in pyrotechnic displays. The life-saving rocket consists of a drawn steel tube with a composition that expels the gases with a pressure of 60 tons to the square inch. It is used to carry a rope to a wrecked vessel near the coast.