.... reactive and capable of combining with most elements. It is essential for respiration of all plants and animals and for practically all combustion. history of oxygen Leonardo da Vinci suggested that air consists of at least two different gases. Before then, air was felt to be an element in its own right. He was also aware that one of these gases supported both flames and life. Oxygen was prepared by several workers before 1772 but these workers did not recognise it as an element. Joseph Priestley is generally credited with its discovery (who made oxygen by heating lead or mercury oxides), but Carl Wilhelm Scheele also r .....

.... of Hawaii, where the terms originated. The stickiest lava forms flows of boulders and rubble called block flows. It may also form mounds of lava called domes. Other lava formations are spatter cones and lava tubes. Spatter cones are steep hills that can get up to 100 feet high. They build up from the spatter of geyser-like eruptions of thick lava. Lava tubes are tunnels formed from fluid lava. As the lava flows, its exterior covering cools and hardens. But the lava below continues to flow. After the flowing lava drains away, it leaves a tunnel. Rock Fragments Rock fragment are usually called tephra and are formed from sticky .....

.... the land in half led to shortages in the production of food because only half of the field was being used. This system of agriculture needed some minor adjustments to increase the production of food without destroying the soil in the process. This new system came about around the year 800. Farmers began to use a new system, the three-field system, to farm their crops. The three field system used one large field like it’s earlier counterpart. The only change, was that the field was divided into three fields. Instead of only getting food from one half of your land, you could use two-thirds of the land to produce your own food .....

.... shape by keeping water and water-soluble compounds from passing through it. The lipids that are waxy are usually used to make protective coatings on the surface of plants and animals. Since a lipid is an organic compound it contains carbon. They also contain hydrogen and oxygen, but in some very complex chains there is also phosphorus and/or nitrogen. Lipids are made by the dehydration synthesis of glycerol and fatty acids. This is when three molecules of fatty acids combine with one molecule of glycerol by taking water out of the solution. Lipids are always huge molecules, which means they have a lot of energy like twi .....

.... pollutants considered that it causes stinging eyes, lung damage, asthma, and acid rain. It is the result of coal-fired power stations. Nitrogen oxides that is produced by the exhaust of cars, causes pneumonia and asphyxia. The outcome of the well known dust particles is often underestimated. It is caused by industrial chimneys, car exhaust, and volcanic eruptions and it effects the environment by toxic effects and damage of the lungs. Radioactive isotopes which are caused by small quantities from nuclear waste and nuclear accidents have an carcinogenic effect on the environment as well. The outcome of chlorfluorocarbons, whic .....

.... was perfected and accomplished. Now this accomplishment has made it possible for the cloning of almost any mammal, including humans. To the average person, exactly how the technique works is unclear. Scientist predicted that by making cells dormant and bringing them close to death, something happens to break the chemical locks (barriers) that keep most of the genes inactive. The mammary cell is inserted into an unfertilized sheep egg cell that has already had all of its own genetic material removed. By fusing the cells together tricks the egg into thinking that it has become fertilized. After being fused together, researchers .....

.... element, which is fifth in abundance in the Earth’s crust. It is essential for forming leaves, bones, shells, and Portland Cement. Calcium occurs in many highly useful compounds such as marble, limestone, and chalk. Plants and animals must have calcium to live. A plant cannot grow without a good supply of calcium. A lack of calcium prevents bones from developing properly. Calcium is the major component of teeth and bones. Calcium must be present for blood to clot. It also helps the nervous system, and it is necessary for muscle contraction. A good dietary intake of calcium is essential for proper growth and developm .....

.... by videotape and "deep-diving submersibles". Last summer a team from the University of Washington and the American Museum of Natural History accomplished the task of bringing four "" to the surface. The method that the team used for retrieval was quite interesting. The team followed a "loggers technique" for detaching the smoker from the Earth’s crust. They used a "choker", like the cables loggers use to drag downed trees to waiting trucks. Another "logger technique" that the team used was a chainsaw. But this one was different it was hydraulically driven and covered with a diamond-coated blade. Even thought the stacks are .....

.... wavelength of IR absorption bands are characteristic of specific types of chemical bonds. An IR spectrophotometer is an instrument which is designed to obtain an infrared spectra of a molecule. An IR spectra is obtained by first irradiating a sample with an IR source of light. The light passes through the sample, which can be in solution or contained within a salt plate, and then onto an IR light detector. The spectrum is analyzed by examining at which frequency the peaks occur. Different peak frequencies indicate different types of vibrational motion and hence, different types of chem .....

.... lifted. The first step to understanding genetic engineering, and embracing its possibilities for society, is to obtain a rough knowledge base of its history and method. The basis for altering the evolutionary process is dependant on the understanding of how individuals pass on characteristics to their offspring. Genetics achieved its first foothold on the secrets of nature's evolutionary process when an Austrian monk named Gregor Mendel developed the first "laws of heredity." Using these laws, scientists studied the characteristics of organisms for most of the next one hundred years following Mendel's discovery. These .....