{"id":8008,"date":"2019-07-02T11:00:30","date_gmt":"2019-07-02T16:00:30","guid":{"rendered":"https:\/\/blog.lib.uiowa.edu\/eng\/?p=8008"},"modified":"2019-09-27T13:44:18","modified_gmt":"2019-09-27T18:44:18","slug":"its-the-4th-of-july","status":"publish","type":"post","link":"https:\/\/blog.lib.uiowa.edu\/eng\/its-the-4th-of-july\/","title":{"rendered":"It’s the 4th of July!!"},"content":{"rendered":"

Summer is here!!<\/strong><\/h4>\n

What can be more summer-like than the 4th<\/sup> of July, picnics, parades and, most of all, fireworks! <\/strong><\/h4>\n

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Fireworks have a long and (yes, I’ll say it) colorful history. Fireworks go back as far as 7th<\/sup> century China.  In 1292 Marco Polo took fireworks back to Italy where the Italians began to develop them as an art form. Settlers brought fireworks to the Americas in the 1600s, and the very first 4th<\/sup> of July celebration with fireworks was in 1777 \u2013 a year after the Declaration of Independence was signed. The earliest patents<\/a> for fireworks go back as far as 1876.<\/p>\n

There are a multitude of different fireworks, but they all fall into three distinct categories. Aerial fireworks include mortars, bottle rockets and Roman candles.  Proximate fireworks are often used indoors for concerts, theatrical presentations and movies. Ground-based fireworks include the familiar firecrackers, snakes, smoke bombs, and sparklers.<\/p>\n

\"\"<\/a>As you are sitting there in the dark, or lying on your back on a blanket and ooohing and aaahing over the amazing color, have you ever wondered what goes into creating those effects? Well, the beautiful colors of the fireworks come from various chemical compounds: red is strontium and lithium; blue is copper; silver or white is burning aluminum titanium and magnesium; orange is calcium; yellow is sodium; green is barium; and the neon green and turquoise are chlorine with barium or copper. Chemicals also affect the appearance of fireworks. Love those sparkly fireworks? Aluminum creates that effect! Glitter comes from antimony, calcium deepens the color, phosphorous creates glow in the dark effects and the smoke effects come from zinc.<\/p>\n

Now cover your ears, here comes the noise! Sound is also influenced by the chemicals used and by the shape of the firework tube. Perhaps surprisingly, the whistle effect is second only to flash powders in being the most hazardous firework effect.  Whistle combinations consist of potassium chlorate or potassium perchlorate as the oxidizer, with a salt of benzoic acid or a substituted benzoic acid. You\u2019ll notice you see the fireworks before you hear the booms. That\u2019s because light travels about a million times faster than sound. Those loud booms are actually sonic booms caused by the expansion of gases. You can calculate how far from the fireworks you are by counting the seconds from the time you see the firework until you hear the boom. To figure the distance in miles simply multiply the number of seconds by .o2.  <\/sup><\/p>\n

\"\"<\/a>There are, not surprisingly, many safety regulations surrounding the production and handling of fireworks. Before safety regulations were enacted there were many accidents which resulted in casualties. When the Treaty of Aix-la Chapelle was signed in 1748 celebrations were held all over Europe. The celebration in Paris had a mass explosion which led to the death of 40 people and over 300 injuries.  It was 1875 before the Explosives Act was introduced. The current Federal Explosives Law and Regulations is from 2012. Each state also regulates the use and availability of fireworks. Go here<\/a> to check the fireworks control laws in your state.<\/p>\n

There are also interesting regulations for the storage of fireworks. One of the hazards of storing fireworks is static electricity.  Staff working in explosive buildings should not wear synthetic clothing or non-conducting footwear. Personnel should also discharge themselves before entering the building with an electrostatic discharger. There are also regulations for conduction, anti-static flooring and the humidification of the room. I found this information interesting and, dare I say, shocking!<\/p>\n

Remember the Treaty of Aix-la Chapelle, back in 1748? George Frederick Handel was commissioned to write an overture for the London celebration of the treaty. He wrote Music for the Royal Fireworks<\/em>,<\/a> and this began the tradition of association between music and fireworks. For more information about creating fireworks displays and their environmental impact, check out Fireworks displays: explosive entertainmen<\/a>t<\/em>, by Dr. Tom Smith.<\/p>\n

Here’s a video of the Overture – complete with fireworks!<\/p>\n