Category Science

Chinese crackers were probably the first fireworks to be made and this was about 2000 years ago. They are still used in China and throughout the East to celebrate weddings, births and religious festivals. They are also used to scare away evil spirits. It is probable that gunpowder was developed in China because they used potassium nitrate (saltpeter) to cure their meat, and so it was readily available.

Fireworks have also been used for centuries in ancient Indian and Siamese ceremonies.

The earliest recorded use of gunpowder in England is by the Franciscan monk Roger Bacon (born 1214). He recorded his experiments with a mixture which was very inadequate by today’s standards but was recognizable as gunpowder. His formula contained charcoal and sulphur because there was no natural source of saltpeter available.

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Thousands of years ago, the Egyptians discovered that it was the yeast which made bread rise and so they were the first people to produce a ‘yeast-raised’ bread.

Yeast is a one-celled plant, so small that it cannot be seen without a microscope. As yeast plants grow and reproduce, they form two substances called ‘enzymes’, invertase and zymase. These enzymes help to change starch to sugar and sugar to alcohol, carbon dioxide and energy.

This energy producing process is called ‘fermentation’. The carbon dioxide formed is a gas which man may use in a number of ways; one of which is baking, particularly bread.

Modern breadmakers add yeast and sugar to the dough as they make it. The starch and sugar in the bread dough serve as food for the yeast. Carbon dioxide is given off and forms bubbles inside the loaf. Heat from the oven causes the gas to expand. This makes the bread rise even more. Finally, the heat drives off the carbon dioxide, and it leaves a light, dry loaf.

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People had been trying for thousands of years to find better ways to preserve food for a long time. The first patent for a ‘tin canister’ for preserving food was granted in England to Peter Durand in 1810. He got the idea from the canisters in which tea was packed. In America, the name became shortened to ‘tin can’, and the industry was called ‘canning’, while in England it is known as ‘tinning’.

The first cannery in the United States was one for fish, and was started by Ezra Dagget in New York City in 1819. Heinz & Company began producing baked beans in tomato sauce at Richmond, Victoria on October 1, 1935. To cam a food successfully, it must be heated enough to kill the organism (moulds, yeasts, bacteria) that may cause fresh food to spoil; the tin can or glass jar must be free from germs and it must be sealed air-tight.

An American inventor, Thomas A. Edison invented the first workable electric lamp in 1879. In the late 1800s electric lamps began to replace gas ones.

On October 21, 1879, Edison created a lamp containing a carbonized thread for the filament. The lamp burned steadily for two days.

The first commercial installation of Edison’s lamp was made in May 1880 on the steamship Columbia. In 1881 a New York City factory was lit with Edison’s system, and the commercial success of the incandescent lamp was quickly established.

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Sir Isaac Newton of Cambridge University in England, first uncovered the secrets of how light is divided up. We think of ordinary light as being ‘white’, but really light is a mixture of red, orange, yellow, green, blue and violet. When sunlight strikes the bevelled edge of a mirror, or the edge of a glass prism, or the surface of a soap bubble, we can see the different hues in the light. What actually happens is that the white light is broken up into the different wave lengths that are seen by our eyes. These wave lengths form a band of parallel stripes, each hue grading into the one next to it. This band is called a ‘spectrum’. In a spectrum the red line is always at one end and the blue violet lines at the other.

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Ben Franklin (1706-1790) was an American with many talents. He was a printer, scientist and politician who played an important part in founding the United States.

He discovered the nature of lightning while flying a kite during a thunderstorm. Franklin noticed sparks jumping from a key tied to the end of the wet string. This could very easily have killed him, but it did not. He went on to invent the lightning conductor, a strip of copper that is run from the top of a building to the ground in order that lightning can earth itself safely.

Lightning is a significant weather hazard and occurs at an average rate of 50 to 100 discharges per second. Lightning rods and metallic conductors can be used to protect a structure by intercepting and diverting the lightning current into the ground as harmlessly as possible. When lightning is likely to occur, people are advised to stay indoors or in a car, away from open doors and windows and to avoid contact with any electrical appliances or plumbing that might be exposed to the outside environment.

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