Science: Fireworks

U. S. fireworks manufacturers last week estimated that U. S. citizens would set off some $4,000,000 of firecrackers, sparklers, roman candles, skyrockets, aerial bombs, pinwheels, squibs, flares, torpedoes, etc. etc. in celebration of Independence Day 1930; in the good old days, a $4,000,000 Fourth of July would have been a very sad Fourth indeed. Fireworks men mourn the time when a piece of punk in the outfield of a baseball park would bring to life a fire portrait of “Theodore Roosevelt, Our President” and cause great huzzahs to shake the bleachers.

Twenty years ago, July 4 was ushered in with 18-in. cannoncrackers which sounded like quarry blasts. These, largest ever made. were constructed with a heavy cardboard case two-thirds filled with saltpetre, carbon and sulphur. In those days, long before and after July 4 fireworkmen were billed like vaudeville teams about the country, the wonders of pyrotechny were displayed to smalltown folk in parks and pastures. Greatest spectacle of these traveling companies was “The Last Days of Pompeii,” a morality pageant on a 576-ft. canvas topped by a 70-ft. Vesuvius. Climax of the spectacle came when 2,000 carousing extras paid for their sins beneath an awesome shower of flares and rockets.

Greatest single fireworks program of all time was given at the St. Louis exposition in 1904 when $50,000 worth of noise, color and excitement were burned and blown up.

An almost staggering blow was given to the fireworks industry when the late Edward W. Bok’s Ladies’ Home Journal before the war against fireworks, printed scores of pictures of children maimed and blinded by them. Following this series Mayor William J. Gaynor signed an ordinance banning fireworks in New York City. Many another municipality, then many a state government followed suit. Then it was that fireworks manufacturers called Science to their aid to construct safer, saner displays. Sparklers of aluminum bronze which throws off incandescent but quick-cooling particles as it burns, were invented for children. Crackers were reduced in size (largest is now 5 in.), then fuses were improved. Skyrockets were made with stronger sticks, roman candles with thicker handles.

Not until the 19th century did pyrotechny make big advances. Prior to this time saltpetre, carbon, sulphur made up the colorless displays. As various metal salts were discovered they were introduced to make colors in fireworks. Strontium and lithium salts give red: barium and copper, green; other copper salts blue. Last great advance was the discovery that magnesium and aluminum salts impart white brilliance to fireworks.

Some of the more familiar display pieces are now made as follows:

Roman Candles. Cardboard tubes are packed in alternate layers with slow-burning powder, quick-burning powder and pressed discs of quick-burning chemicals containing a coloring salt. When lighted the slow-burning powder spews, finally reaches the disc. When this takes fire it ignites the quick-burning powder which makes a mild explosion, expels the flaming disc.

Rocket. In the fuse end of the rocket a medium powder is mixed with metal filings packed under tremendous pressure. The ignited gases rush to escape through the rear, push against the air and drive the rocket upward. As it goes the metal filings become hot, spew out the back making the tail. When the fire breaks into the front chamber, it explodes a charge of strong powder which bursts the shell, showers balls similar to those in the Roman candle.

Aerial Bombs. These are fired from a mortar much as a cannon ball. When they reach a certain height in the air a time fuse burns out, causes the explosion.